bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of nutrient loading, dissolved inorganic carbon and higher trophic levels on the interaction between submerged plants and periphyton
Authors: Jones J. Iwan , Young Johnstone O. , Eaton John W. , Moss Brian
Published: March 2003

We studied the growth of a submerged aquatic plant in relation to periphytic and planktonic algae over a range of nutrient and dissolved inorganic carbon (DIC) availabilities.

In consecutive years two factorial experiments were conducted in 48 artificial ponds (each 3.14 m3), comprising four concentrations of DIC (1.5, 2.5, 3.5 or 4.5 mm) each crossed with three separate nutrient loadings (10 µg L−1 P and 0.2 mg L N, 50 µg L−1 P and 1 mg L N, or 200 µg L−1 P and 4 mg L N). The second experiment differed by the inclusion of fish in the ponds.

In the first year DIC had no effect on plant growth, but nutrient loading did. Plants failed to grow in treatments where phytoplankton density was high (> 100 µg L−1). Where phytoplankton was low, high numbers of invertebrates colonized the ponds, and periphyton abundance on the plants was low. In the second year, where phytoplankton never achieved the densities of the previous year, there was a significant effect of DIC concentration on plant growth but not of nutrients. Invertebrate abundance was lower and periphyton on the plants correspondingly higher.

In both years increased nutrient loading had no effect on the abundance of periphyton growing on the surface of the plants. Periphyton abundance was determined by the density of grazing invertebrates in the ponds.

There was a negative relationship between periphyton density and final plant density, which became significantly less steep with increasing DIC, indicating that periphyton and plants were competing for carbon.

DIC concentration has the potential to influence community structure in shallow lakes, altering competitive interactions between periphyton and plants and rendering low DIC lakes more prone to loss of plants when nutrient loading increases. However, the expression of this competition between periphyton and plants will depend on the density of grazing invertebrates present, which is itself influenced by the intensity of fish predation on those invertebrates.
Counting dendritic spines in brain tissue slices by image correlation spectroscopy analysis
Authors: Wiseman P. W. , Capani F. , Squier J. A. , Martone M. E.
Published: March 2003

Growth of new micrometre sized projections called dendritic spines in neurones has been linked to the encoding of long‐term memories in vertebrates. Numerous studies have been carried out at both the light and electron microscopy level to quantify dendritic spine densities in brain tissue in laboratory animals. Currently, such efforts using light microscopy have relied on manual counting of spines in confocal or two‐photon optical slice images of tissue containing fluorescently labelled spines. This manual approach can be slow and tedious, especially for samples with high spine densities. We introduce an alternative way of performing spine counting that uses an applied image intensity threshold followed by spatial image correlation spectroscopy (ICS) analysis. We investigated the effect of particle sizes above the diffraction limit on the autocorrelation analysis as well as the influence of background fluorescence. Our results show that, for well labelled cerebellar tissue samples imaged with a signal‐to‐noise ratio of 5 or greater, ICS‐based spine counts can be conducted with the same 15–20% precision as manual counting, but much more rapidly.
P‐glycoprotein expression in rat brain endothelial cells:  evidence for regulation by transient oxidative stress
Authors: Felix Robert A. , Barrand Margery A.
Published: March 2003

During ischaemia/reperfusion, cells of the blood–brain barrier are subjected to oxidative stress. This study uses primary cultured rat brain endothelial cells to examine the effect of such stresses on expression of multidrug transporters. H2O2 up to 500 µm applied to cell monolayers caused a concentration‐dependent increase in expression of P‐glycoprotein (Pgp) but not of multidrug resistance‐associated protein (Mrp1). Concentrations > 250 µm H2O2 decreased cell viability. Application of 100 µm H2O2 caused a significant increase after 48 h in Pgp functional activity, as assessed from [3H]vincristine accumulation experiments. At this concentration, H2O2 produced a transient increase within 10 min followed by a sustained decrease in levels of intracellular reactive oxygen species (iROS), detectable by flow cytometry. Reoxygenation of cell monolayers after 6 h hypoxia gave rise to a similar transient increase in iROS and this also led to increased Pgp expression by 24 h. Increases were also observed within 4 h after both H2O2 and hypoxia/reoxygenation treatments in mdr1a and mdr1b mRNA. Evidence suggests this was due to enhanced transcription rather than mRNA stabilization. Therefore, oxidative stress, by changing Pgp expression, may affect movement of Pgp substrates in and out of the brain.
A new role for apolipoprotein E: modulating transport of polyunsaturated phospholipid molecular species in synaptic plasma membranes
Authors: Igbavboa Urule , Hamilton Jillonne , Kim Hee‐Yong , Sun Grace Y. , Wood W. Gibson
Published: March 2003

Phospholipids and their acyl group composition are important in providing the proper membrane environment for membrane protein structure and function. In particular, the highly unsaturated phospholipids in synaptic plasma membranes in the CNS are known to play an important role in modulating receptor function and neurotransmitter release processes. Apolipoprotein E (apoE) is a major apolipoprotein in the CNS, mediating the transport of cholesterol, phospholipids and their fatty acids, particularly in reparative mechanisms during neuronal injury. This study was performed to determine whether deficiency in the apoE gene contributes to an alteration of the phospholipids in synaptic plasma membranes. Phospholipid molecular species were identified and quantitated by HPLC/electrospray ionization‐mass spectrometry. Analysis of the different phospholipid classes in membranes of apoE‐deficient and C57BL/6 J mice indicated no obvious differences in the distribution of different phospholipid classes but substantial differences in composition of phospholipid molecular species. Of special interest was the prevalence of phospholipids (phosphatidylcholine, diacyl‐phosphatidylethanolamine, and phosphatidylserine) with 22:6n‐3 in both the sn‐1 and sn‐2 positions of SPM and these phospholipid species were significantly higher in apoE‐deficient mice as compared to control mice. Since polyunsaturated fatty acids in neurons are mainly supplied by astrocytes, these results revealed a new role for apoE in regulating polyunsaturated phospholipid molecular species in neuronal membranes.
Regulation of tumor necrosis factor‐α expression  by CD40 ligation in BV‐2 microglial cells
Authors: Jana Malabendu , Dasgupta Subhajit , Liu Xiaojuan , Pahan Kalipada
Published: March 2003

Ligation of CD40 has been shown to induce/stimulate the expression of tumor necrosis factor‐α (TNF‐α) in microglial cells. This study delineates the mechanism by which CD40 ligation regulates the expression of TNF‐α in BV‐2 microglial cells. There was very little induction of TNF‐α by ligation of CD40 alone by either cross‐linking antibodies against CD40 or␣recombinant CD40 ligand (CD154). The absence of any increase in TNF‐α production by CD40 ligation alone even in CD40‐overexpressed BV‐2 microglial cells suggest that signal transduced by the ligation of CD40 alone is not sufficient for strong induction of TNF‐α. However, CD40 ligation markedly induced the production of TNF‐α as well as the expression of TNF‐α mRNA in interferon‐γ (IFN‐γ)‐stimulated BV‐2 glial cells. Ligation of CD40 in CD40‐overexpressed cells markedly enhanced the expression of TNF‐α in the presence of IFN‐γ. To understand the mechanism of CD40 ligation‐mediated induction/stimulation of TNF‐α, we investigated the role of nuclear factor‐κB (NF‐κB) and C/EBPβ. IFN‐γ alone was able to induce the activation of NF‐κB as well as C/EBPβ. However, CD40 ligation alone in the presence or absence of CD40 overexpression induced the activation of only NF‐κB and not that of C/EBPβ, suggesting that the activation of NF‐κB alone by CD40 ligation is not sufficient to induce the expression of TNF‐α and that the activation of C/EBPβ is also necessary for strong induction of TNF‐α. Consistently, a dominant‐negative mutant of p65 (Δp65) and that of C/EBPβ (ΔC/EBPβ) inhibited the expression of TNF‐α in BV‐2 microglial cells stimulated with the combination of IFN‐γ and CD40 ligand. Taken together, these studies suggest that activation of both NF‐κB and C/EBPβ is important for strong induction of TNF‐α and that CD40 ligation regulates the expression of TNF‐α by modulating the activation of only NF‐κB but not that of C/EBPβ.
Activation of caspase‐3 alone is insufficient for apoptotic morphological changes in human neuroblastoma cells
Authors: Racke Margaret M. , Mosior Marian , Kovacevic Steve , Chang Chan Hsin S. , Glasebrook Andrew L. , Roehm Neal W. , Na Songqing
Published: March 2003

Activated caspase‐3 is considered an important enzyme in the cell death pathway. To study the specific role of caspase‐3 activation in neuronal cells, we generated a stable tetracycline‐regulated SK‐N‐MC neuroblastoma cell line, which expressed a highly efficient self‐activating chimeric␣caspase‐3, consisting of the caspase‐1 prodomain fused to the caspase‐3 catalytic domain. Under expression‐inducing conditions, we observed a time‐dependent increase of processed caspase‐3 by immunostaining for the active form of the enzyme, intracellular caspase‐3 enzyme activity, as well as poly(ADP‐ribose) polymerase (PARP) cleavage. Induced expression of the caspase fusion protein showed predominantly caspase‐3 activity without any apoptotic morphological changes. In contrast, staurosporine treatment of the same cells resulted in activation of multiple caspases and profound apoptotic morphology. Our work provides evidence that auto‐activation of caspase‐3 can be efficiently achieved with a longer prodomain and that neuronal cell apoptosis may require another caspase or activation of multiple caspase enzymes.
Are flowers morphologically adapted to take advantage of electrostatic forces in pollination?
Authors: Vaknin Yiftach , Gan‐mor Samuel , Bechar Avital , Ronen Beni , Eisikowitch Dan
Published: March 2003

The relationship between floral morphology and electrostatic pollination was studied here. To test the effects of floral morphology on pollen deposition on the stigma and other floral parts by means of electrostatic forces, metal replicas of almond (Amygdalus communis) flowers were constructed and then dusted with electrostatically charged and uncharged almond pollen. The pollen was applied to the flowers with a specially designed electrostatic powder‐coating device.

Pollen deposition on the flower was found to be higher when the pollen was electrostatically charged than when it was not. Most of the charged pollen grains were deposited on the corolla extremities and on the stigma, whereas uncharged pollen grains were evenly distributed on the entire flower.

Stigma exsertion was the most important morphological feature of the flower promoting pollen deposition on the stigma when electrostatic charge was used. Large flowers with corollas showed higher electrodeposition on the corolla than smaller, narrower ones.

These results collectively imply that morphological features of a plant might be adaptations to take advantage of electrostatic forces. This provided us with a very important tool for future research on floral morphology and pollination biology.
Mycorrhiza Helper Bacteria stimulate ectomycorrhizal symbiosis of Acacia holosericea with Pisolithus alba
Authors: Founoune H. , Duponnois R. , Bâ A. M. , Sall S. , Branget I. , Lorquin J. , Neyra M. , Chotte J. L.
Published: March 2003

The influence of two fluorescent pseudomonads strains (HR13 and HR26) on the ectomycorrhizal symbiosis between Pisolithus alba and Acacia holosericea is reported here.

 We measured ectomycorrhizal establishment, fungal growth in the soil (by HPLC) and soil microbial biomass (using the fumigation–extraction method) in treatments with or without pseudomonads.

 Bacteria inoculated with the fungal symbiont stimulated ectomycorrhizal formation and shoot or root biomass. Only HR13 significantly increased fungal biomass in the soil. The bacteria stimulated fungal growth and production of phenolic compounds. Sequence analysis of the two fluorescent Pseudomonas revealed 99% homologuey between HR13 and P. monteilii, and 98% between HR26 and P. resinovorans.

 It is clear that some bacteria (Mycorrhiza Helper Bacteria) can stimulate the establishment of the ectomycorrhizal symbiosis in tropical conditions.
Stem and branch respiration of beech: from tree measurements to estimations at the stand level
Authors: Damesin C. , Ceschia E. , Le Goff N. , Ottorini J‐M. , Dufrêne E.
Published: March 2003

Stem and branch respiration of 30‐yr‐oldFagus sylvaticatrees was measured in a temperate forest for 1 yr to estimate the annual flux at the stand level.

 The seasonal response of respiration to air temperature was determined using infra‐red gas analysis (IRGA) systems. Annual respiration was derived from half‐hourly temperature recording and allometric relations established for the same forest.

 The basal respiration rate at 15°C (R15) increased greatly during the growing season. On a volume basis, monthly means of R15were higher for branches than for stems. For stems, Q10was relatively constant throughout the year, with an annual average of 1.7. Estimated annual respiration was approx. 325 g C m−2ground surface area yr−1with 50% of this amount attributed to growth respiration.

 Stem and branch respiration played a major role in the annual carbon balance of the beech stand. It represented approx. one third of the ecosystem‐level carbon loss from respiration. The magnitude of crown respiration makes it obvious that information on branch respiration characteristics is required for reliable estimations at the stand level.
An integrated and comparative view of pea genetic and cytogenetic maps
Authors: Ellis T. H. N. , Poyser S. J.
Published: March 2003

Molecular marker maps have been generated for pea (Pisum sativum), but these have not been well integrated with previous genetic and cytogenetic maps. Here, these data sets are brought together to summarize the current state of knowledge, exploiting the common genetic markers used in many different studies. The pea linkage map was known to be simply related to the maps of lentil and chickpea, and these relationships are presented in the context of the present map. The genomes of these legumes are interpreted as having an equivalent gene content, but differing in their repetitive DNAs.
Full Field Tensile Strain Shearography of Welded Specimens
Authors: Steinchen W. , Kupfer G. , Mäckel P.
Published: March 2003

Digital shearography is a coherent optical method used in conjunction with digital image processing. It allows the shearogram, which depicts directly displacement derivatives, in real time to be observed and to be evaluated numerically. Strains are functions of the displacement derivatives. Thus, the shearogram contains the strain information, but usually it includes both the in‐plane strain, e.g. ∂u/∂x, and the out‐of‐plane component, e.g. ∂w/∂x. In order to get the pure in‐plane strain as well as the pure out‐of‐plane component, two linearly independent directions of illumination (usually the same but mutual and sequential illuminations) are introduced in the measuring device. The shearograms for each illuminating direction are evaluated by applying the phase shifting technique. The result by subtracting the phase maps of the two shearograms yields a new fringe pattern depicting the pure in‐plane strain component and the result by adding the phase maps corresponds to the pure out‐of‐plane component. The theory and an application to non‐destructive tensile testing are demonstrated in this paper. Its applications for determining the strain distribution of the homogeneous and inhomogeneous material and an error analysis are presented.
Engineering Measurement and Testing of Land‐based Structures Using Strain Gauges
Authors: Maguire J. R. , Phillips P.
Published: March 2003

This paper presents a number of case histories illustrating the benefits and costs of certain types of engineering measurement and testing, with a focus on strain‐gauged land‐based structures. The benefits are described mainly in terms of safety, economy and environment. The costs are related to the amount of data collected and processed. The paper concludes with some technical and financial guidance for clients, owners, consultants and contractors who may be considering these types of activities.
Ordovician high‐grade metamorphism of a newly recognised late Neoproterozoic terrane in the northern Harts Range,central Australia
Authors: Buick I. S. , Miller J. A. , Williams I. S. , Cartwright I.
Published: March 2003

Granulite facies rocks from the northernmost Harts Range Complex (Arunta Inlier, central Australia) have previously been interpreted as recording a single clockwise cycle of presumed Palaeoproterozoic metamorphism (800–875 °C and >9–10 kbar) and subsequent decompression in a kilometre‐scale, E‐W striking zone of noncoaxial, high‐grade (c. 700–735 °C and 5.8–6.4 kbar) deformation. However, new SHRIMP U‐Pb age determinations of zircon, monazite and titanite from partially melted metabasites and metapelites indicate that granulite facies metamorphism occurred not in the Proterozoic, but in the Ordovician (c. 470 Ma).

The youngest metamorphic zircon overgrowths from two metabasites (probably meta‐volcaniclastics) yield 206Pb/238U ages of 478±4 Ma and 471±7 Ma, whereas those from two metapelites yield ages of 463±5 Ma and 461±4 Ma. Monazite from the two metapelites gave ages equal within error to those from metamorphic zircon rims in the same rock (457±5 Ma and 462±5 Ma, respectively). Zircon, and possibly monazite ages are interpreted as dating precipitation of these minerals from crystallizing melt within leucosomes. In contrast, titanite from the two metabasites yield 206Pb/238U ages that are much younger (411±5 Ma & 417±7 Ma, respectively) than those of coexisting zircon, which might indicate that the terrane cooled slowly following final melt crystallization. One metabasite has a second titanite population with an age of 384±7 Ma, which reflects titanite growth and/or recrystallization during the 400–300 Ma Alice Springs Orogeny. The c. 380 Ma titanite age is indistinguishable from the age of magmatic zircon from a small, late and weakly deformed plug of biotite granite that intruded the granulites at 387±4 Ma. These data suggest that the northern Harts Range has been subject to at least two periods of reworking (475–460 Ma & 400–300 Ma) during the Palaeozoic.

Detrital zircon from the metapelites and metabasites, and inherited zircon from the granite, yield similar ranges of Proterozoic ages, with distinct age clusters at c. 1300–1000 and c. 650 Ma. These data imply that the deposition ages of the protoliths to the Harts Range Complex are late Neoproterozoic or early Palaeozoic, not Palaeoproterozoic as previously assumed.
Fluid‐rock history of granulite facies humite‐marbles from Ambasamudram, southern India.
Authors: Satish‐Kumar M. , Wada H. , Santosh M. , Yoshida M.
Published: March 2003

An extensive humite‐bearing marble horizon within a supracrustal sequence at Ambasamudram, southern India, was studied using petrological and stable isotopic techniques to define its metamorphic history and fluid characteristics. At peak metamorphic temperatures of 775±73°C, based on calcite‐graphite carbon isotope thermometry, the mineral assemblages suggest layer‐by‐layer control of fluid compositions. Clinohumite + calcite‐bearing assemblages suggestXCO2 < 0.4 (at 700°C and 5 kbar), calcite + forsterite + K‐feldspar‐bearing assemblages suggestXCO2>0.9 (at 790°C); and local wollastonite + scapolite + grossular‐bearing zones formed atXCO2of c. 0.3. Retrograde reaction textures such as scapolite + quartz symplectites after feldspar and calcite and replacement of dolomite + diopside or tremolite+dolomite after calcite+forsterite or calcite+clinohumite are indicative of retrogression under highXCO2conditions. Calcite preserves late Proterozoic carbon and oxygen isotopic signatures and the marble lacks evidence for extensive retrograde fluid infiltration, while during prograde metamorphism the possible infiltration of aqueous fluids did not produce significant isotopic resetting. Isotopic zonation of calcite and graphite grains was likely produced by localized CO2fluid infiltration during retrogression. Contrary to the widespread occurrence of humite‐marbles related to retrograde aqueous fluid infiltration, the Ambasamudram humite‐marbles record a prograde‐to‐peak metamorphic humite formation and retrogression under conditions of lowXH2O.
Metamorphism of the Central Anatolian Crystalline Complex, Turkey: influence of orogen‐normal collision vs. wrench‐dominated tectonics on P–T–t paths
Authors: Whitney D. L. , Teyssier C. , Dilek Y. , Fayon A. K.
Published: March 2003

The Central Anatolian Crystalline Complex (CACC) is a microcontinent in the Alpine–Himalayan belt. It has previously been considered as a coherent structural entity, but, although the entire CACC is comprised of similar rocks (primarily metasedimentary rocks and granitoids), it consists of at least four tectonic blocks characterized by different P–T–t paths. These blocks are the Kırşehir (north‐west), Akdağ (north‐east), Niğde (south) and Aksaray (west) massifs. The northern massifs experienced thrusting and folding during collision and were slowly exhumed by erosion; metamorphic rocks are characterized by clockwise P–T paths at moderate P–T and local low‐P–high‐T (LP–HT) overprinting in the highest grade rocks. Apatite fission track ages are Eocene to Oligocene (47–32 Ma). The Aksaray block represents the hot, shallow mid‐crust of a Late Cretaceous–early Tertiary arc. It is dominated by intrusions; rare metapelitic rocks record low‐P (< 4 kbar) regional metamorphism overprinted by LP–HT contact metamorphism. Apatite fission track ages are 50–45 Ma. The Niğde massif is different from the other CACC blocks because it evolved as a core complex in a wrench‐dominated setting. It is characterized by clockwise P–T paths at moderate P–T followed by widespread LP–HT metamorphism. Apatite fission track ages are Miocene (12–9 Ma), significantly younger than those in the northern massifs. Niğde rocks resided in the mid‐crust at a time when the rest of the CACC was at or near the Earth's surface. Variations in P–T–t and tectonic histories — especially timing of exhumation — between the northern and southern CACC reflect the difference between head‐on collision vs. mid‐crustal wrenching.
Interlayer and Si content of phengite in HP–LT carpholite‐bearing metapelites
Authors: Agard P. , Vidal O. , Goffé B.
Published: March 2003

Phengite occurring along with carpholite±lawsonite and/or chloritoid in HP–LT domains shows not only variable Si–(Mg+Fe) contents, but also variable interlayer contents (IC). To determine whether these chemical variations are coherently related to variation in P–T conditions on a regional scale, c. 100 rock samples were sampled in metapelites metamorphosed at conditions varying from 350 °C, 8 to 12 kbar to 450–500 °C, 18 to 20 kbar (Schistes Lustrés complex, franco‐italian Western Alps). Based on microstructural and habit criteria, four types of phengite were differentiated that are related either to the rock mineralogy (carpholite vs chloritoid bearing samples) or correspond to various generations of phengite occurring in the same rock sample or thin section. Microprobe analyses reveal that each type of phengite is characterized by a specific composition and that phengite associated with carpholite has a lower interlayer content than phengite associated with chloritoid. The successive generations of retrograde phengite overgrowing carpholite point to a large decrease of interlayer content (c. 0.9–0.7 pfu) and (Fe+Mg) content (c. 0.25–0 pfu) with decreasing P–T conditions. This change is best accounted for by a gradual increase of the pyrophyllite component. In contrast, phengite from higher‐temperature, chloritoid‐bearing rock samples shows an almost constant interlayer content (c. 0.9–0.95 pfu) but a larger decrease of (Fe+Mg) content (c. 0.6–0.1 pfu). Hence, (1) the composition of the different phengite generations occurring (metastably) in the same rock sample may be used to retrieve points in P–T loops and (2) the pyrophyllitic substitution in phengite is large at low‐temperature conditions and cannot be ignored. Thermobarometric estimates based on the Si‐content alone will therefore result in pressure over‐estimates. We propose a tentative location of the phengite Si and IC isopleths in P–T space which could allow a direct determination of the P–T conditions in carpholite‐bearing rocks. Especially in some carpholite‐bearing rocks, new thermodynamic models accounting for tschermak and pyrophyllitic substitution are also required prior to making reliable thermobarometric estimates in HP‐LT metapelites.
Fractionation of bulk rock composition due to porphyroblast growth: effects on eclogite facies mineral equilibria, Pam Peninsula, New Caledonia
Authors: Marmo B. A. , Clarke G. L. , Powell R.
Published: March 2003

Chemically zoned porphyroblasts in metamorphic rocks indicate that diffusional processes could not maintain equilibrium conditions on a grain scale during porphyroblast growth or establish it afterwards. An effect of this inability to maintain equilibrium is the progressive removal of elements forming garnet cores from any metamorphic reaction that occurs at the porphyroblast boundaries or in the matrix of the rock. To examine this effect on mineral assemblages, the Bence–Albee matrix correction was applied to X‐ray intensity maps collected using eclogite samples from northern New Caledonia in order to determine the chemical composition of all parts of the sample. The manipulation of these element maps allows a quantitative analysis of the fractionation of the bulk rock composition between garnet cores and the matrix. A series of calculated equilibrium‐volume compositions represents the change in matrix chemistry with progressive elemental fractionation as a consequence of prograde garnet growth under high‐P conditions. Pressure–temperature pseudosections are calculated for these compositions, in the CaO–Na2O–FeO–MgO–Al2O3–SiO2–H2O system. Assemblages, modal proportions and mineral textures observed in the New Caledonian eclogites can be closely modelled by progressively ‘removing’ elements forming garnet cores from the bulk rock composition. The pseudosections demonstrate how chemical fractionation effects the peak metamorphic assemblage, prograde textures and the development of retrograde assemblages.
Assessing the extent of disequilibrium and overstepping of prograde metamorphic reactions in metapelites from the Bushveld Complex aureole, South Africa
Authors: Waters D. J. , Lovegrove D. P.
Published: March 2003

Andalusite–staurolite–biotite hornfels metamorphosed beneath the mafic layered rocks of the Bushveld Complex, South Africa, preserves a detailed record of the relative timing of porphyroblast growth and metamorphic reactions. The sequence inferred from microstructures shows considerable overlap of the period of growth of porphyroblasts of staurolite, cordierite, biotite and andalusite, and the persistence over a similar interval of the reactant porphyroblastic phase chloritoid. This is inconsistent with calculations of equilibrium phase relations, and implies that disequilibrium processes controlled the prograde reaction sequence, despite the slow heating rates involved (1 °C per 10 000 yr). The early appearance of cordierite by a metastable reaction and its subsequent disappearance indicates that delayed nucleation of porphyroblastic phases, rather than simply sluggish reaction, is required to account for the sequence of growth. The predicted reactions for the first appearance of andalusite and staurolite have low entropy of reaction, and do not occur until they have been overtaken in terms of reaction affinity by high‐entropy devolatilisation reactions involving the breakdown of chlorite. Once the porphyroblasts have nucleated, metastable chloritoid‐breakdown reactions also contribute to their growth. The implied magnitude of the critical overstepping for andalusite nucleation is around 5 kJ mole−1 (equivalent to 40 °C for the chlorite‐breakdown reaction), and that for other phases is expected to decrease in the order andalusite>staurolite>cordierite. Coupling between nucleation rate, crystal growth rates and the resulting grain size distribution suggests that the rate constants of natural reactions are at least an order of magnitude lower than those measured in the laboratory. Pseudomorphs after chloritoid and cordierite conserve volume but not Al or other species of low mobility, suggesting a breakdown mechanism controlled by an interface process such as the slow dissolution of the refractory porphyroblast phase, rather than by a transport step.
Impact‐induced melting of Archean granulites in the Vredefort Dome, South Africa. I: anatexis of metapelitic granulites
Authors: Gibson R. L.
Published: March 2003

Mid‐crustal Archean pelitic granulites in the Vredefort Dome experienced a static, low‐P granulite facies overprint associated with the formation of the dome by meteorite impact at 2.02 Ga. Heating and exhumation were virtually instantaneous, with the main source of heat being provided by energy released from nonadiabatic decay of the impact shock wave. Maximum temperatures within a radius of a few kilometres of the centre of the structure exceeded 900 °C and locally even exceeded 1350 °C. This led to comprehensive melting of the precursor Archean granulite assemblages (Grt + Bt + Qtz + Pl + Ksp ± Crd ± Opx ± Sil) followed by peritectic crystallization of aluminous alkali feldspar+Crd + Spl ± Crn ± Sil parageneses and the segregation of small, evolved, biotite leucogranite bodies. However, at a distance of c. 6 km from the centre pre‐impact rock features are largely preserved, although partial replacement of garnet by symplectitic coronas of Crd + Opx ± Spl ± Pl and biotite by orthopyroxene indicate that peak temperatures approached 775 ± 50 °C. Thin interstitial moats of K‐feldspar are closely associated with the orthopyroxene coronas; they are interpreted as the remnants of low‐proportion partial melts generated by biotite breakdown. Both the textures and mineral compositional data support reduced equilibration volumes in these rocks, which reflect rapid isobaric cooling following shock heating and exhumation. The high temperatures and strong lateral thermal gradient are consistent with the modelled impact‐induced isotherm pattern for a 200–300 km diameter impact crater.
Thermodynamic modelling of the reaction muscovite+cordierite→Al2SiO5+biotite+quartz+ H2O: constraints from natural assemblages and implications for the metapelitic petrogenetic grid
Authors: Pattison D. R. M. , Spear F. S. , Debuhr C. L. , Cheney J. T. , Guidotti C. V.
Published: March 2003

The reaction muscovite+cordierite→biotite+Al2SiO5 +quartz+H2O is of considerable importance in the low pressure metamorphism of pelitic rocks: (1) its operation is implied in the widespread assemblage Ms + Crd +And± Sil + Bt + Qtz, a common mineral assemblage in contact aureoles and low pressure regional terranes; (2) it is potentially an important equilibrium for pressure estimation in low pressure assemblages lacking garnet; and (3) it has been used to distinguish between clockwise and anticlockwise P–T paths in low pressure metamorphic settings. Experiments and thermodynamic databases provide conflicting constraints on the slope and position of the reaction, with most thermodynamic databases predicting a positive slope for the reaction. Evidence from mineral assemblages and microtextures from a large number of natural prograde sequences, in particular contact aureoles, is most consistent with a negative slope (andalusite and/or sillimanite occurs upgrade of, and may show evidence for replacement of, cordierite). Mineral compositional trends as a function of grade are variable but taken as a whole are more consistent with a negative slope than a positive slope. Thermodynamic modelling of reaction 1 and associated equilibria results in a low pressure metapelitic petrogenetic grid in the system K2O–FeO–MgO–Al2O3–SiO2–H2O (KFMASH) which satisfies most of the natural and experimental constraints. Contouring of the Fe–Mg divariant interval represented by reaction 1 allows for pressure estimation in garnet‐absent andalusite+cordierite‐bearing schists and hornfelses. The revised topology of reaction 1 allows for improved analysis of P–T paths from mineral assemblage sequences and microtextures in the same rocks.
ICT in higher education: evaluating outcomes for health education
Authors: Lockyer L. , Patterson J. , Harper B.
Published: March 2003

Abstract This paper presents an investigation that examined and compared the effectiveness of collaborative tutorial activities carried out in both web‐based and face‐to‐face learning environments within an undergraduate health education subject. Effectiveness of the different learning environments was measured in terms of observed learning outcomes, analysis of learner interactions and reported perceptions of the learners regarding their experience. Results demonstrated that web‐based environments, with embedded collaborative activities, can effectively foster rich learning experiences that result in attaining positive learning outcomes.
The effects of metacognition and email interactions on learning graphing
Authors: Kramarski B. , Ritkof R.
Published: March 2003

Abstract  The purpose of this study was twofold: First, to investigate the effects of metacognition and email interaction between teacher‐student on learning to interpret and construct graphs. Second, to describe the email interaction on three levels of interaction: tutorial, metacognitive and life. Participants were 50 ninth‐grade students (boys and girls) who studied graphs in two classes. One class (n = 25) was exposed to EXCEL software embedded within email interaction (EMAIL) and the other class (n = 25) was exposed to EXCEL software embedded within email interaction and metacognitive instruction (EMAIL + META). Results indicated that the EMAIL + META students significantly outperformed the EMAIL students on graph interpretation and graph construction. In particular the effects were observed on students' ability to explain mathematical reasoning and on reducing misconceptions regarding graphs. Furthermore, qualitative analysis of the EMAIL messages indicated that the EMAIL + META students frequently used different levels of interaction in their email interactions than the EMAIL students.
Discipline differences in role and use of ICT to support group‐based learning
Authors: Hammond N. , Bennett C.
Published: March 2003

Abstract Small‐group teaching and learning is traditionally central to UK Higher Education. This paper explores how disciplines differ in their use of information and communication technologies (ICT) to support small‐group activities. A framework for considering discipline differences and evidence from surveys and case studies conducted by the ASTER Project are presented. While many uses of ICT are common across the disciplines studied (drawn from the Humanities, Physical Sciences and Psychology), there are also some striking differences, in particular the infrequent use of ICT to facilitate discussion in the Physical Sciences compared to the pattern of use in the other disciplines studied. It is vital that such differences are considered when advising on the take‐up of innovative teaching and learning methods.
The effect of metacognitive training on mathematical word‐problem solving
Authors: Teong S.K.
Published: March 2003

This study demonstrates how explicit metacognitive training influences the mathematical word‐problem solving of forty 11–12‐year‐old low achievers in a cognitive‐apprenticeship, computer‐based environment. Results from the experimental and case study designs revealed that experimental students outperformed control students on ability to solve word‐problems on their individual written measures; experimental students developed the ability to ascertain when to make metacognitive decisions, and elicit better regulated metacognitive decisions than control students; knowing when and how to use metacognitive strategies is an important determinant to successful word‐problem solving; and the cognitive‐apprenticeship‐computer‐based environment appears to amplify low achievers' metacognitive and cognitive behaviours during word‐problem solving.
Palatability and toxicity of fipronil as a systemic insecticide in a bromadiolone rodenticide bait for rat and flea control
Authors: Leirs H. , Larsen K. S. , Lodal J.
Published: March 2003

Abstract. Vector control in plague‐infested areas requires a simultaneous killing of rodents and their fleas. We investigated the efficacy of a combination of a systemic insecticide, fipronil, in a rodenticide bait formulation under laboratory conditions. Four different concentrations of fipronil (0.05%, 0.005%, 0.0005% with acetone as a solvent, and 0.05% with propylene glycol as a solvent) and two controls (solvents only) were combined with the rodenticide bait (crushed organically grown wheat with 0.005% bromadiolone). Each concentration was offered together with an untreated non‐poisonous challenge bait to 10 singly caged Rattus rattus L., each with 100 rat fleas Xenopsylla cheopis Rothschild (Siphonaptera: Pulicidae) in the nest. Treated bait consumption was relatively low and an unsatisfactory rat mortality of around 50% only was obtained in all tests. The palatability of the bait, however, was not affected by the fipronil concentration. Even at the lowest fipronil concentration, average flea mortality was still above 95%, and doses of more than 1 mg fipronil per kg rat body weight gave a nearly complete kill of fleas. Fipronil can be highly effective as a systemic insecticide to for flea control, provided that a more attractive bait base for roof rats is used.
Evaluation of biological and chemical insecticide mixture against Aedes aegypti larvae and adults by thermal fogging in Singapore
Authors: Chung Y. K. , Lam‐Phua S. G. , Chua Y. T. , Yatiman R.
Published: March 2003

Abstract. To improve the operational efficiency of dengue vector control in Singapore, larvicide and adulticide were applied together by thermal fog generator (Agrofog® AF40). The mixture consisted of Bacillus thuringiensis var. israelensis (Vectobac® 12 AS) as biological larvicide at 1.5 L/ha and pirimiphos‐methyl (Actellic® 50 EC) as adulticide at 100 g ai/ha, diluted 10‐fold with water. Aerosol of this mixture was evaluated against the mosquito Aedes aegypti (L.) (Diptera: Culicidae) in bioassays using cages of 10 adult females exposed at heights of 0.3–2.4 m and distances of 3–12 m from the hand‐held generator. Cups containing 200 mL water were treated at ground level by exposure to the aerosol application at the same distances from the generator. Subsequent larval bioassays on days 1, 7, 14, 21 and 28 post‐spray involved exposing 20 larvae/cup for 48 h. Droplets had VMD 57 µm and female mosquitoes were killed by 2 s exposure to the aerosol at 3 m. We obtained 92–100% mortality of the adult mosquitoes and 100% control of larvae at 3 m distance, but only 10–13% mortality at 12 m from the fogger. In treated cups, larvae showed high mortality (92%) when exposed for 48 h even 1 month post‐treatment. Results demonstrate the practical advantage of using this mixture of Vectobac® 12AS and Actellic® 50 EC for simultaneous control of Aedes adults and larvae, with prolonged larvicidal efficacy in treated containers.
Seasonal reproduction and host infestation rates for nycteribiids of the large bentwing bat
Authors: Archer M. S. , Cardinal B. R.
Published: March 2003

Abstract. Large numbers of the nycteribiid species Nycteribia parilis vicaria Maa, Penicillidia (Penicillidia) oceanica Bigot and Penicillidia (Penicillidia) Maa (Diptera: Nycteribiidae) were collected from the bat Miniopterus schreibersii Kuhl (Chiroptera: Vespertilionidae) during a study on this bat's population genetics conducted largely in southern Australia. Bats were trapped in all seasons and at a number of locations throughout the ranges of the nycteribiids. Nycteribia parilis vicaria was the most common species captured. Gravid females of the three species were trapped in spring and summer and gravid female P. (P.) oceanica and N. parilis vicaria were trapped in autumn. Newly emerged adults of P. (P.) oceanica and N. parilis vicaria were captured in spring and autumn. Nycteribiid loads for individual bats were low, and there was no direct evidence of a detrimental effect on bats.
Human and other faeces as breeding media of the trachoma vector Musca sorbens
Authors: Emerson P. M. , Bailey R. L. , Walraven G. E. L. , Lindsay S. W.
Published: March 2003

Abstract. The fly Musca sorbens Wiedemann (Diptera: Muscidae) apparently transmits Chlamydia trachomatis, causing human trachoma. The literature indicates that M. sorbens breeds predominantly in isolated human faeces on the soil surface, but not in covered pit latrines. We sought to identify breeding media of M. sorbens in a rural Gambian village endemic for trachoma. Test breeding media were presented for oviposition on soil‐filled buckets and monitored for adult emergence. Musca sorbens emerged from human (6/9 trials), calf (3/9), cow (3/9), dog (2/9) and goat (1/9) faeces, but not from horse faeces, composting kitchen scraps or a soil control (0/9 of each). After adjusting for mass of medium, the greatest number of flies emerged from human faeces (1426 flies/kg). Median time for emergence was 9 (inter quartile range = 8–9.75) days post‐oviposition. Of all flies emerging from faeces 81% were M. sorbens. Male and female flies emerging from human faeces were significantly larger than those from other media, suggesting that they would be more fecund and live longer than smaller flies from other sources. Female flies caught from children's eyes were of a similar size to those from human faeces, but significantly larger than those from other media. We consider that human faeces are the best larval medium for M. sorbens, although some breeding also occurs in animal faeces. Removal of human faeces from the environment, through the provision of basic sanitation, is likely to greatly reduce fly density, eye contact and hence trachoma transmission, but if faeces of other animals are present M. sorbens will persist.
Evidence for an impact on the incidence of canine leishmaniasis by the mass use of deltamethrin‐impregnated dog collars in southern Italy
Authors: Maroli M. , Mizzoni V. , Siragusa C. , D'Orazi A. , Gradoni L.
Published: March 2003

Abstract.Dogs are the domestic reservoir ofLeishmania infantumNicolle (Kinetoplastida: Trypanosomatidae), the agent of zoonotic human visceral leishmaniasis. In southern Europe, where canine leishmaniasis (CanL) is widespread due toL. infantum, killing seropositive dogs is considered unacceptable and drug treatment has low efficacy in preventing transmission. We made a field evaluation of the efficacy of deltamethrin dog collars in a CanL focus of southern Italy, Mount Vesuvius area of Campania region, where the vector isPhlebotomus perniciosusNewstead (Diptera: Psychodidae), by assessing their impact on the incidence of CanL in an intervention town, compared to that in dogs of control towns where no collars were fitted. During two consecutive transmission seasons, collars were fitted to 350 (1998) and 354 (1999) dogs from San Sebastiano al Vesuvio (70% of the canine population). Control dogs (371 and 264 in the 2 years, respectively) were from four towns of the same area. Before each transmission season, the CanL seroprevalence in the intervention and control towns was evaluated by cross‐sectional surveys and found to be similar (about 15% in 1998 and 10% in 1999, respectively). After each transmission period, incidence rates of seroconversions were determined in adult dogs that were serologically negative before the season under evaluation, and in puppies. After the 1998 season, 2.7% of the dogs in the intervention town seroconverted compared to 5.4% in the control towns (50% protection,P = 0.15). After the 1999 season, 3.5% of collared dogs seroconverted compared to 25.8% of control dogs (86% protection,P < 0.001). The increase in seroconversion rates recorded in control dogs suggests an increase in theLeishmaniaforce of infection in the canine reservoir during the 1999 sandfly season, as supported by the concomitant increase of human cases in control towns and in the whole Campania region. Our results suggest that the impact of mass use of deltamethrin‐impregnated dog collars on the incidence of CanL may be negligible during low transmission seasons, or probably in low endemic foci, but can be very strong when the force of transmission is high.
A key to the adults of species of blowflies in southern Australia known or suspected to breed in carrion
Authors: Wallman J. F.
Published: March 2003

Abstract. The reliable morphological identification of carrion‐breeding blowflies is important ecologically, as well as for medical, veterinary and forensic reasons. To date, no comprehensive key has been available to make this possible for workers in southern Australia. An illustrated key is presented to the adults of all species of blowflies (Diptera: Calliphoridae) south of 30° S known or suspected to breed in carrion (species exclusive to Queensland and/or the Northern Territory are excluded).
Chemical ecology of triatomine bugs: vectors of Chagas disease
Authors: Cruz‐López L. , Malo E. A. , Rojas J. C. , Morgan E. D.
Published: March 2003

Abstract. Knowledge of chemical ecology of haematophagous triatomine bugs (Hemiptera: Heteroptera: Reduviidae) could be of practical value because this polyphyletic subfamily includes species of medical importance, such as vectors of Trypanosoma cruzi Chagas (Kinetoplastida: Trypanosomatidae), the aetiological agent of Chagas disease. For particular species of Dipetalogaster, Panstrongylus, Rhodnius and Triatoma, therefore, we review information on exocrine glands and products, interpreting their apparent roles as semiochemicals in the aggregation, alarm, defence, host‐finding and sexual behaviour of these Triatominae.
Basal relationships of Coleoptera inferred from 18S rDNA sequences
Authors: Caterino Michael S. , Shull Verel L. , Hammond Peter M. , Vogler Alfried P.
Published: March 2003

The basal relationships of the hyperdiverse insect order Coleoptera (beetles) have proven difficult to resolve. Examination of beetle suborder relationships using 18S ribosomal DNA reveals a previously unproposed relationship among the four major lineages: [(Archostemata(Myxophaga(Adephaga, Polyphaga)))]. Adding representatives of most other insect orders results in a non‐monophyletic Coleoptera. However, constraining Coleoptera and its suborders to be monophyletic, in analyses of beetle and outgroup sequences, also results in the above beetle relationships, with the root placed between Archostemata and the remaining suborders.