bluuebunny/crossref_metadata_2025 huggingface dataset:
Structures of mixed gold-silver cluster cations (AgmAun+,m+n<6): Ion mobility measurements and density-functional calculations
Authors: Weis Patrick , Welz Oliver , Vollmer Elena , Kappes Manfred M.
Published: December 2003

The collision cross sections of AgmAun+ (m+n)<6 cluster ions were determined. For bimetallic clusters, we observe a significant intracluster charge transfer leaving most of the ions positive charge on the silver atoms. The mixed trimeric ions Ag2Au+ and AgAu2+ are triangular like the pure gold and silver trimers. Most of the tetrameric clusters are rhombus shaped, with the exception of Ag3Au+, which has a Y structure with the gold atom in the center. Among the pentamers we find distorted X structures for all systems. For Ag2Au3+ we find an additional isomer which is a trigonal bipyramid. These findings are in line with predictions based on density-functional theory calculations, i.e., all these structures either represent the global minima or are within less than 0.1 eV of the predicted global minimum.
Superexcited state reconstruction of HCl using photoelectron and photoion imaging
Authors: Romanescu Constantin , Manzhos Sergei , Boldovsky Dmitrii , Clarke Jennifer , Loock Hans-Peter
Published: December 2003

The velocity-map imaging technique was used to record photoelectron and photofragment ion images of HCl following two-photon excitation of the E Σ+(0+), V 1Σ+(0+) (ν=9,10,11) states and subsequent ionization. The images allowed us to determine the branching ratios between autoionization and dissociation channels for the different intermediate states. These branching ratios can be explained on the basis of intermediate state electron configurations, since the configuration largely prohibits direct ionization in a one-electron process, and competition between autoionization and dissociation into H* (n=2)+Cl and H+Cl*(4s,4p,3d) is observed. From a fit to the vibrationally resolved photoelectron spectrum of HCl+ it is apparent that a single superexcited state acts as a gateway to autoionization and dissociation into H+Cl*(4s). Potential reconstruction of the superexcited state to autoionization was undertaken and from a comparison of different autoionization models it appears most likely that the gateway state is a purely repulsive and low-n Rydberg state with a (4Π) ion core.
An overlap expansion method for improving ab initio model potentials: Anisotropic intermolecular potentials of N2, CO, and C2H2 with He*(2 3S)
Authors: Maeda Satoshi , Yamazaki Masakazu , Kishimoto Naoki , Ohno Koichi
Published: December 2003

An overlap expansion method is proposed for improving ab initio model potentials. Correction terms are expanded in terms of overlap integrals between orbitals of the interacting system. The method is used to improve ab initio model potentials for N2+He*(2 3S), CO+He*(2 3S), and C2H2+He*(2 3S). Physical meanings of the optimization are elucidated in terms of target orbitals. Correction terms are found to be dominated by the components of HOMO, LUMO, next-HOMO, and next-LUMO on the target molecule. The present overlap expansion method using a limited number of correction terms related to frontier orbitals provides an efficient and intuitive approach for construction of highly anisotropic intermolecular interaction potentials.
Fractionation of peptide with disulfide bond for quantum mechanical calculation of interaction energy with molecules
Authors: Chen X. H. , Zhang D. W. , Zhang J. Z. H.
Published: December 2003

We present a computational study of a recently developed molecular fractionation with conjugated caps (MFCC) method for application to peptide/protein that has disulfide bonds. Specifically, we employ the MFCC approach to generate peptide fragments in which a disulfide bond is cut and a pair of conjugated caps are inserted. The method is tested on two peptides interacting with a water molecule. The first is a dipeptide consisting of two cysteines (Cys–Cys) connected by a disulfide bond and the second is a seven amino acid peptide consisting of Gly–Cys–Gly–Gly–Gly–Cys–Gly with a disulfide cross link. One-dimensional peptide–water potential curves are computed using the MFCC method at various ab initio levels for a number of interaction geometries. The calculated interaction energies are found to be in excellent agreement with the results obtained from the corresponding full system ab initio calculations for both peptide/water systems. The current study provides further numerical support for the accuracy of the MFCC method in full quantum mechanical calculation of protein/peptide that contains disulfide bonds.
Spectroscopy of highly excited vibrational states of HCN in its ground electronic state
Authors: Martı́nez R. Z. , Lehmann Kevin K. , Carter Stuart
Published: December 2003

An experimental technique based on a scheme of vibrationally mediated photodissociation has been developed and applied to the spectroscopic study of highly excited vibrational states in HCN, with energies between 29 000 and 30 000 cm−1. The technique consists of four sequential steps: in the first one, a high power laser is used to vibrationally excite the sample to an intermediate state, typically (0,0,4), the ν3 mode being approximately equivalent to the C–H stretching vibration. Then a second laser is used to search for transitions between this intermediate state and highly vibrationally excited states. When one of these transitions is found, HCN molecules are transferred to a highly excited vibrational state. Third, a ultraviolet laser photodissociates the highly excited molecules to produce H and CN radicals in its A 2Π electronic state. Finally, a fourth laser (probe) detects the presence of the CN(A) photofragments by means of an A→B→X laser induced fluorescence scheme. The spectra obtained with this technique, consisting of several rotationally resolved vibrational bands, have been analyzed. The positions and rotational parameters of the states observed are presented and compared with the results of a state-of-the-art variational calculation.
Crossed beams and theoretical studies of the O(3P)+CH4→H+OCH3 reaction excitation function
Authors: Troya Diego , Schatz George C. , Garton Donna J. , Brunsvold Amy L. , Minton Timothy K.
Published: December 2003

The excitation function for the reaction, O(3P)+CH4→H+OCH3, has been measured in a crossed molecular beams experiment and determined with direct dynamics calculations that use the quasiclassical trajectory method in conjunction with a recently developed semiempirical Hamiltonian. Good agreement is found between experiment and theory, enabling us to address two fundamental issues for the O(3P)+CH4 reaction that arise for all O(3P)+saturated hydrocarbon reactions: (1) the importance of triplet excited states that correlate adiabatically to ground-state reactants and products and (2) the importance of intersystem crossing processes involving the lowest singlet surface [corresponding to reaction with O(1D)]. Our results indicate that the first excited triplet surface contributes substantially to the cross section when the collision energy exceeds the reaction barrier (∼2 eV) by more than 0.5 eV. Although triplet-singlet crossings may occur at all energies, we have found that their effect on the excitation function is negligible for the collision energies studied—up to 1.5 eV above threshold.
On combining molecular dynamics and stochastic dynamics simulations to compute reaction rates in liquids
Authors: Guo Yin , Thompson Donald L.
Published: December 2003

An approach that combines molecular dynamics and stochastic dynamics calculations for obtaining reaction rates in liquids is investigated by studying the cis→trans isomerization of HONO in liquid krypton. The isomerization rates are computed for several liquid densities by employing full-dimensional molecular-dynamics simulations. The rates are also computed by employing the stochastic dynamics method for a wide range of collision frequencies. Comparisons of the two sets of the computed rates show that for a wide range of liquid densities there is a simple linear relation between the liquid density ρ and the collision frequency α, that is, α=cρ. This suggests that once the constant c is determined from a molecular-dynamics calculation at a single density, the reaction rates can be obtained from stochastic dynamics calculations for the entire range of liquid densities where α=cρ holds. The applicability of the combined molecular dynamics and stochastic dynamics approach provides a practical means for obtaining rate constants at considerable savings of computer time compared to that required by using full-dimensional molecular-dynamics simulations alone.
Implicit solvation based on generalized Born theory in different dielectric environments
Authors: Feig Michael , Im Wonpil , Brooks Charles L.
Published: December 2003

In this paper we are investigating the effect of the dielectric environment on atomic Born radii used in generalized Born (GB) methods. Motivated by the Kirkwood expression for the reaction field of a single off-center charge in a spherical cavity, we are proposing extended formalisms for the calculation of Born radii as a function of external and internal dielectric constants. We demonstrate that reaction field energies calculated from environmentally dependent Born radii lead to much improved agreement with Poisson–Boltzmann solutions for low dielectric external environments, such as biological membranes or organic solvent, compared to previous methods where the calculation of Born radii does not depend on the environment. We also examine how this new approach can be applied for the calculation of transfer free energies from vacuum to a given external dielectric for a system with an internal dielectric larger than one. This has not been possible with standard GB theory but is relevant when scoring minimized or average structures with implicit solvent.
Temperature modeling of laser-irradiated azo-polymer thin films
Authors: Yager Kevin G. , Barrett Christopher J.
Published: December 2003

Azobenzene polymer thin films exhibit reversible surface mass transport when irradiated with a light intensity and/or polarization gradient, although the exact mechanism remains unknown. In order to address the role of thermal effects in the surface relief grating formation process peculiar to azo polymers, a cellular automaton simulation was developed to model heat flow in thin films undergoing laser irradiation. Typical irradiation intensities of 50 mW/cm2 resulted in film temperature rises on the order of 5 K, confirmed experimentally. The temperature gradient between the light maxima and minima was found, however, to stabilize at only 10−4 K within 2 μs. These results indicate that thermal effects play a negligible role during inscription, for films of any thickness. Experiments monitoring surface relief grating formation on substrates of different thermal conductivity confirm that inscription is insensitive to film temperature. Further simulations suggest that high-intensity pulsed irradiation leads to destructive temperatures and sample ablation, not to reversible optical mass transport.
Monte Carlo molecular simulation of the hydration of Na–montmorillonite at reservoir conditions
Authors: de Pablo L. , Chávez M. L. , Sum A. K. , de Pablo J. J.
Published: December 2003

The hydration of Na-saturated Wyoming-type montmorillonite is investigated by Monte Carlo simulations at constant stress in the NPzzT ensemble and at constant chemical potential in the μVT ensemble, at the sedimentary basin temperature of 353 K and pressure of 625 bar, equivalent to 2–4 km depth. The simulations use procedures established in Chávez-Páez et al. [J. Chem. Phys. 114, 1405 (2001)]. At these conditions, simulations predict a single stable form of 1,2-water layer Na–montmorillonite, containing 164.38 mg/g or 53.37 molecules/layer of adsorbed water and having a spacing of 12.72 Å. The corresponding density is 0.32 g/ml. Sodium ions are coordinated with six molecules of water separated 2.30–2.33 Å. Water molecules are closer to the central interlayer plane and the spacing is larger than that at 300 K and 1 bar. The interlayer configuration consists of two symmetrical layers of oriented water molecules 1.038 Å from the central plane, with the hydrogen atoms in two outermost layers, 3.826 Å apart, and the sodium ions on the central plane located between the water layers. The interlayer configuration can be considered to be a stable two-layer intermediate between the one- and two-layer hydrates. Our simulations do not predict formation of other hydrates of Na–montmorillonite at 353 K and 615 bar.
Vibrational relaxation in methyl hydrocarbons at high temperatures: Propane, isobutene, isobutane, neopentane, and toluene
Authors: Kiefer J. H. , Sahukar G. C. , Santhanam S. , Srinivasan N. K. , Tranter R. S.
Published: December 2003

Vibrational relaxation has been seen in shock waves in propane, isobutene, isobutane, neopentane, and toluene dilute in krypton with the laser–schlieren technique. These experiments cover about 600–2200 K and post-shock pressures from 5 to 29 Torr. The process cannot be resolved in any for T<600 K, or in any for large molecule fraction. All the ultrasonic measurements of relaxation in these at room temperature show characteristic times in the 1–5 ns atm range, corresponding to fewer than five collisions, whereas the relaxation times in the shock waves range from 20 to 200 ns atm, with a clearly defined negative or “inverted” temperature dependence. It would seem the observed slowdown of relaxation with increasing T is simply a consequence of the much increased energy transfer required at high temperature in such large polyatomics when this is combined with a collision efficiency, here interpreted as 〈ΔE〉down, already so large it cannot much increase. The simple method for the extraction of a 〈ΔE〉down from relaxation data offered here by consideration of the energy relaxation equation for Evib=0 appears to be original and should prove quite useful in connecting thermal relaxation data to values obtained from spectroscopy and master-equation analyses. Here it is found that the derived 〈ΔE〉down extrapolate well to room temperature ultrasonic measurements, showing a slight increase with temperature.
Fast vibrational self-consistent field calculations through a reduced mode–mode coupling scheme
Authors: Benoit David M.
Published: December 2003

We present a new methodology to perform fast correlation-corrected vibrational self-consistent field (CC-VSCF) calculations using ab initio potential energy points calculated on the fly. Our method is based on the replacement of all-electron basis sets with a pseudo-potential basis for heavy atoms, and on an efficient reduction of the number of pair-coupling elements used in the CC-VSCF procedure. The method is applied to several test systems: H2O, NH3, and CH4, where it proves to be efficient, providing a speedup factor of 2 compared to a standard CC-VSCF calculation. We also apply our technique to the simulation of the vibrational spectrum of ethane and show that very accurate results can be obtained with a substantial speedup for this system.
Vibrational branching ratios in photoionization of CO and N2
Authors: Rathbone G. J. , Rao R. M. , Poliakoff E. D. , Wang Kwanghsi , McKoy V.
Published: December 2003

We report results of experimental and theoretical studies of the vibrational branching ratios for CO 4σ−1 photoionization from 20 to 185 eV. Comparison with results for the 2σu−1 channel of the isoelectronic N2 molecule shows the branching ratios for these two systems to be qualitatively different due to the underlying scattering dynamics: CO has a shape resonance at low energy but lacks a Cooper minimum at higher energies whereas the situation is reversed for N2.
Surface reaction mechanisms of hydrazine on Si(100)-2×1 surface: NH3 desorption pathways
Authors: Lim Chultack , Choi Cheol Ho
Published: December 2003

Multireference as well as single-reference wave functions were adopted to study the surface reaction mechanisms of hydrazine. The initial surface mechanisms resemble those of ammonia and its methyl derivatives. MRMP2 values indicate that the lifetime of initial molecularly adsorbed species should be longer than previously suggested. High energy path as well as low energy path of subsequent surface reactions were found. The theoretical initial surface product of low energy path is consistent with the experimentally suggested structure. Both paths eventually lead to very stable surface products, which are also consistent with the experimentally suggested structures. The reaction channels of the experimentally observed NH3 desorptions were also revealed. It was shown that the high reactivity of hydrazine as compared to ammonia and its methyl derivatives is due to the high nucleophilic ability of the additional nitrogen atom of hydrazine.
Electron–phonon interactions in charged cubic fluorocarbon cluster, (CF)8
Authors: Kato Takashi , Yamabe Tokio
Published: December 2003

Electron–phonon interactions in the charged cubic fluorocarbon, (CF)8 are studied, and compared with those in charged (CH)8 and (CD)8. The A1g mode of 1470 cm−1 much more strongly couples to the a1g lowest unoccupied molecular orbitals (LUMO) than the A1g mode of 554 cm−1 in (CF)8. The T2g mode of 1030 cm−1, the Eg mode of 980 cm−1, and the A1g mode of 1470 cm−1 strongly couple to the t2u highest occupied molecular orbitals (HOMO) in (CF)8. The total electron–phonon coupling constants for the monoanion (l−1) and monocation (l+1) of (CF)8 are estimated to be 0.932 and 0.585 eV, respectively. The logarithmically averaged phonon frequencies for the monoanion (ωln,−1) and monocation (ωln,+1) of (CF)8 are estimated to be 1365 and 998 cm−1, respectively. The l−1 and ωln,−1 values increase much more significantly by H–F substitution than by H–D substitution in cubane. The larger displacements of carbon atoms in the high frequency vibronic active mode in (CF)8 than those in (CD)8 due to larger atomic mass of fluorine than that of deuterium, and the unchanged electron distributions in the LUMO somewhat localized on carbon atoms as a consequence of H–F and H–D substitution in cubane, are the main reason why the l−1 and ωln,−1 values increase much more significantly by H–F substitution than by H–D substitution. The l+1 and ωln,+1 values less significantly change than the l−1 and ωln,−1 values by H–F substitution as well as by H–D substitution in cubane. This is because the t2u HOMO in (CF)8 and the t2g HOMO in (CH)8 are somewhat localized on fluorine atoms, and thus, the high frequency vibronic active modes in which the displacements of carbon atoms are large cannot necessarily very strongly couple to the HOMO somewhat localized on fluorine atoms in (CF)8.
Optical pump–terahertz probe spectroscopy of dyes in solutions: Probing the dynamics of liquid solvent or solid precipitate?
Authors: Kadlec Filip , Kadlec Christelle , Kužel Petr , Slavı́ček Petr , Jungwirth Pavel
Published: December 2003

The optical pump–terahertz probe spectroscopy was used together with ab initio calculations and molecular dynamics simulations to investigate ultrafast dynamics following electronic excitation of Coumarin 153 and TBNC (2,11,20,29-tetra-tert-butyl-2,3-naphtalocyanine) dyes in polar solvents. By scanning the terahertz waveform for different pump–probe delays this experimental technique allows us to obtain two dimensional spectra directly reflecting the temporal response of the system. A distinct signal was obtained for TBNC in chloroform, 2-propanol, and n-butanol, while no signal was recorded for Coumarin 153 in either of these solvents. We explain the nonequilibrium signal detected in TBNC solutions by the presence of a solid, polycrystalline phase of the dye resulting from irradiating the solution by intense optical pulses.
Anthelmintic resistance in sheep nematodes in Australia: the need for new approaches
Authors: Besier R. B. , Love S. C. J.
Published: December 2003

Sheep worm infections increasingly threaten the profitability of the Australian sheep industry as the prevalence and severity of anthelmintic resistance continues to rise. Field experiments have demonstrated that the use of drenches that are of reduced efficacy due to resistance can reduce wool production by 10% and significantly reduce sheep sale value. The major factor in benzimidazole (BZ) and levamisole (LV) resistance, and in part macrocyclic lactone (ML) resistance in Haemonchus contortus, is considered to be the excessive frequency of treatment. In Ostertagia circumcincta, ML resistance appears to be related chiefly to interactions between the environment and the time of treatment, where resistant worms surviving drenches are not significantly diluted by worms acquired after treatment. Resistance to the BZs and LV affects almost all Australian sheep farms, and on most drench efficacy is now below a useful level. ML resistance is common in O. circumcincta in Western Australia, and increasingly prevalent in H. contortus in summer rainfall regions. Closantel resistance is a major threat to H.�contortus control in northern New South Wales and southern Queensland. The organophosphate naphthalophos, especially when used in combination with other compounds, has proved useful although variable in efficacy. It is essential that the sheep industry adopts approaches that minimise reliance on chemical control, such as the breeding of worm resistant sheep, use of specific grazing strategies for worm control and apply flock treatment tactics to minimise further resistance development. New non-chemical technologies under development are also expected to contribute to more sustainable worm control. Nutritional regimens that minimise the impact of worm infections and enhance the immune response require investigation and integration into sustainable control practices.
Effects of protein supplementation of young sheep on resistance development and resilience to parasitic nematodes
Authors: Steel J. W.
Published: December 2003

The influence of dietary protein content, particularly the supply of metabolisable protein, on immunocompetence and on resilience to pathogenic effects during continuous exposure of young sheep to infective larvae is reviewed for the most important abomasal and small intestinal nematodes infecting young sheep in Australian grazing systems. In lambs infected with Haemonchus contortus supplementary protein improves both development of immunity and resilience in breeds of sheep that are susceptible to haemonchosis, but in relatively resistant breeds dietary supplementation appears unnecessary. Recent studies indicate that the increased protein requirements of Merino weaners parasitised by H. contortus would be met by diets containing about 190 g crude protein/kg dry matter, depending on the rumen degradability of the dietary protein source and level of feed intake. Some evidence exists for an enhanced immune response to Teladorsagia circumcincta in lambs receiving an increased supply of protein at the intestines.Response to protein supplementation of lambs infected with Trichostrongylus colubriformis depends on the metabolisable protein content of the basal diet and on the period of exposure to incoming larvae. Where the basal diet only meets requirements for maintenance or low growth rates, increased supply of rumen undegradable protein enhances immune expression in terms of reducing faecal egg count and expelling adult worms, but does not appear to limit the initial establishment of incoming larvae. Effects on growth rate and wool production are most pronounced during the period of worm expulsion, indicating that this phase of the immune response competes with production when nutrient resources, and particularly protein, are limited.Field trials in the Armidale region have shown that supplementation with protein meals of Merino weaners, exposed to natural infection from pasture, can reduce faecal egg count and improve resilience in terms of both growth rate and wool production. These effects may persist for some time after supplementation ceases. Further work is needed to determine the generality of these responses in other sheep-producing regions and genotypes and to establish cost-effective supplementation strategies.
Metabolic effects of host defence responses during gastrointestinal parasitism in sheep
Authors: Colditz I. G.
Published: December 2003

Following stimulation of the immune system, tissue trauma, or exposure to some stressors, there can be activation of the acute phase response (APR). This is a primitive defence reaction that helps protect the host against noxious insults. Part of the response involvess a change in priorities for nutrient utilisation, when the pro-inflammatory cytokines IL-1α/β, TNFα, IL-6 and IFNα/β override the normal hypothalamic-somatotropic control of nutrient utilisation. The pro-inflammatory cytokines reduce protein synthesis and increase protein catabolism in muscle, induce synthesis of acute phase proteins in liver, and decrease de novo fatty acid synthesis and increase lipolysis in adipose tissue. In the central nervous system there is induction of fever, which increases metabolic rate, and induction of sickness behaviour. There are few reports in the literature of studies on the APR during gastrointestinal nematode (GIN) infection in sheep. However, IL-6 message is present in mucosa during Trichostrongylus colubriformis infection and mast cells in many species contain preformed TNFα. The changes in appetite, growth and nitrogen metabolism seen during GIN parasitism in sheep are in accord with the systemic effects of the APR. This review reports studies on activation of the APR in mastitis and fly strike, and the effects of APR on wool growth in high and low tensile strength genotypes and during Haemonchus contortus infection. The modified capacity of tissues to take up amino acids during pro-inflammatory cytokine perturbation of nutrient utilisation may limit the capacity for dietary supplementation to remedy the cost of host defence. Genetic variation may occur in production of pro-inflammatory cytokines or in tissue sensitivity to pro-inflammatory cytokines during GIN infection and may provide a basis for selection for resilience. Some questions for future research are identified.
Coral dominance at the reef - sediment interface in marginal coral
communities at Sodwana Bay, South Africa
Authors: Schleyer M. H. , Celliers L.
Published: December 2003

Sedimentation is an important factor that influences the composition of coral communities. The high-latitude, marginal coral community in the central reef complex at Sodwana Bay, South Africa, is subjected to sedimentation at the reef–sediment interface. A lens of bioclastic sediment surrounds the sandstone reefs in the area and acts as a scouring and smothering agent. This affects the composition of the subcommunity on the reef margin at the reef–sediment interface. The interface was studied on two reefs in the complex and their subcommunities did not differ. Alcyoniidae and Scleractinia (34.4% and 34.4% cover, respectively) are the dominant taxa in the reef–sediment subcommunity, which includes genera such as Sinularia, Lobophytum, Sarcophyton, Montipora, Favia and Astreopora (in decreasing order of abundance). Sediment-tolerant species are prevalent, the Alcyoniidae being the most prominent and tolerant by virtue of their morphology. Corals in this environment are generally flat and fairly rigid colonies of Lobophytum and Sinularia spp. (14% and 10% cover, respectively), some with lobes to channel the movement of surge-driven sediment, or are erect, soft and pliable forms such as Sarcophyton spp. (10% cover) that easily shed sediment. Their dominance in this constantly disturbed environment may also be attributable to the low mortality, slow growth and overall persistence of the Alcyoniidae described in the literature.
Diurnal and tidal movements of snapper (Pagrus auratus, Sparidae)
in an estuarine environment
Authors: Hartill B. W. , Morrison M. A. , Smith M. D. , Boubée J. , Parsons D. M.
Published: December 2003

Using individually coded acoustic transponders and an array of 15 moored receivers (detection range ~300 m), the temporal and spatial movements of the temperate snapper Pagrus auratus (Sparidae) were studied within an estuary. Of the 28 fish initially tagged, 20 were subsequently detected within the study area for up to 70 days. The spatial scale of daily movements was in the order of hundreds of metres for most fish, suggesting relatively restricted home ranges over the period monitored (November–January). The detectability of fish remaining in the estuary was lower at night, probably because of fish moving out of the main channel and onto surrounding shallow banks during darkness. Temporal movement patterns detected using spectral analyses (Fast Fourier Transforms) were predominantly diurnal, with subordinate tidal behaviour also evident in some fish. These results demonstrate that in this system, snapper occupy relatively small (hundreds of metres) and discrete areas of soft sediment seafloor, within which repeated, predictable movements are made. Variability among fish has highlighted the need for a better understanding of the relationship between fish behaviour and fine-scale habitat features (metres).
Localised movement of snapper (Pagrus auratus, Sparidae) in a large
subtropical marine embayment
Authors: Sumpton Wayne D. , Sawynok Bill , Carstens Neil
Published: December 2003

Snapper were tagged with dart and anchor tags in order to determine movement and the contribution of juveniles inhabiting estuarine areas to the offshore adult population. Laboratory experiments showed that loss of anchor tags was greater than dart tags, although this was not reflected in the results of field trials. A total of 6572 individuals were tagged in field experiments, of which 509 (7.7%) were recaptured. Only four of over 2500 fish tagged and released in Moreton Bay were recaptured in waters outside the bay, suggesting the bay is not an important source of recruits to the offshore fishery. However, problems associated with tag loss and mortality meant that the actual contribution of juveniles to the offshore fisheries remained unclear. Most snapper movements were localised; only ~1% of movements exceeded 100 km. Movements of snapper were mainly directed northward against the prevailing direction of the East Australian Current. Snapper were considered to be a suitable species for marine reserve protection owing to their relatively localised movement patterns.
Elevated sea-surface temperature, reduced provisioning and reproductive failure of wedge-tailed shearwaters (Puffinus pacificus) in the southern Great Barrier Reef, Australia
Authors: Smithers B. V. , Peck D. R. , Krockenberger A. K. , Congdon B. C.
Published: December 2003

During the 2002 austral summer abnormally high sea-surface temperatures (SST) occurred in the southern Great Barrier Reef (GBR), Australia. This phenomenon was accompanied by reduced provisioning, decreased growth rates and reproductive failure of wedge-tailed shearwaters in the region. In 2002, adults were unable to compensate for changes in either the availability and/or accessibility of forage-fish by increasing food loads or foraging rates. This is one of few studies to explicitly correlate decreases in chick provisioning with above-average annual variation in SST and is the first to do so for a tropical seabird species in the western Pacific. It adds to an increasing number of data sets identifying the potential negative impacts of increasing SST at upper-trophic levels. As SST continue to rise with global climate change, our results predict substantial detrimental effects on seabird populations of the GBR. This finding has important implications for both seabird and coral reef ecosystem management in the region. Our results also suggest that wedge-tailed shearwaters are sensitive indicators to changes in forage-fish availability/accessibility associated with SST variation that can be used to develop models of, and monitor for, these potential impacts.
Long-term movement patterns of continental shelf and inner gulf snapper (Pagrus auratus, Sparidae) from tagging in the Shark Bay region of Western Australia
Authors: Moran M. , Burton C. , Jenke J.
Published: December 2003

Snapper is an important commercial and recreational target species in the Shark Bay region of Western Australia. The present study aimed to define the range of movements of snapper by tagging in the two inner gulfs of Shark Bay and on oceanic fishing grounds adjacent to the Bay. Recaptures by fishers fell to low levels within 4 years after tagging, but small numbers of recaptures were still being made up to 15 years after release. There was no mixing of snapper populations between the two inner gulfs nor was there any movement between the ocean and the inner bay. This supports genetic and other evidence for the existence of several separate stocks in the region. Snapper of the ocean stock were mostly recaptured within 20 km of their release point, although a few fish moved long distances of up to 370 km southwards along the continental shelf. The tagged snapper tended to become more dispersed along the shelf with increasing years at liberty. Yet, an empirical model indicated that of the snapper recruiting to the main oceanic fishing grounds near Koks Island, which have a mean life expectancy in the fishery of 1.5 years, 76% would remain within 93 km (50 nautical miles), even after 6 years. The distinct stocks and their movement characteristics are significant for snapper fishery management in the Shark Bay region.
Diet, feeding behaviour and habitat utilisation of the blue stingray Dasyatis chrysonota (Smith, 1828) in South African waters
Authors: Ebert David A. , Cowley Paul D.
Published: December 2003

Analysis of stomach contents for Dasyatis chrysonota revealed that diet varied with size and habitat. The diet of all size classes in the surf zone was comprised primarily of Callianassa spp., Donax spp. and unidentified polychaete species. The medium and large size classes fed primarily on Donax spp., whereas the very large size class fed mainly on Callianassa spp. Polychaetes were of secondary importance as prey for the medium size class. The diet of D. chrysonota in the nearshore zone consisted mainly of Balanoglossus capensis and Callianassa spp. Balanoglossus capensis decreased from an index of relative importance (IRI) of 75.3% for the medium size class to 59.9% for the very large size class, whereas Callianassa spp. increased from 22.8% to 39.4% between the medium and the very large size classes. The offshore zone was the only area in which small size class D. chrysonota were caught. The diet of these small D. chrysonota was primarily polychaetes and amphipods. Polychaetes increased in importance in the medium size class, but declined in each successively larger size class. Conversely, Pterygosquilla armata capensis became the single most important prey item for the very large size class, comprising an IRI of 50.9%. The behaviour pattern used by D. chrysonota to locate and extract prey is described.
Adoption of Broadband Internet in Korea: The Role of Experience in Building Attitudes
Authors: Oh Sangjo , Ahn Joongho , Kim Beomsoo
Published: December 2003

Although many countries are attempting to build an information infrastructure and accelerate the adoption of broadband Internet access technology, the results are not always satisfactory. The focus of earlier research on the diffusion and adoption of broadband Internet access has been primarily on the construction of a national-level infrastructure or on macro-level factors such as government policies, market competition and the density of population. This research highlights the individual-level factors affecting the adoption of broadband access, integrating various views on the adoption and diffusion of technology, including the technology acceptance model, theory of planned behaviour and diffusion of innovation model. An extended technology acceptance model incorporating the notion of perceived resources is proved to be relevant in the adoption of broadband technologies. It was found that innovation attributes, such as compatibility, visibility and result demonstrability, have an impact on constructs in the extended technology acceptance model such as perceived usefulness, perceived ease of use and perceived resources. These results also support the idea that congruent experiences and opportunities in adopting a new technology affect user attitudes through the three extended technology acceptance model constructs above. This research suggests that efforts should be made to expand the compatible experience base of broadband Internet in order to facilitate its adoption and use. This paper also provides an extensive review of the adoption behaviour of individuals by incorporating different views and theories.
A web of Stakeholders and Strategies: A Case of Broadband Diffusion in South Korea
Authors: Choudrie Jyoti , Papazafeiropoulou Anastasia , Lee Heejin
Published: December 2003

When a new technology is launched, its diffusion becomes an issue of importance. There are various stakeholders that influence diffusion. The question that remains to be determined is their identification and roles. This paper outlines how the strategies pursued by a government acting as the key stakeholder affected the diffusion of a new technology. The analysis is based on a theoretical framework derived from innovation diffusion and stakeholder theories. The empirical evidence comes from a study of broadband development in South Korea. A web of stakeholders and strategies is drawn in order to identify the major stakeholders involved and highlight their relations. The case of South Korea offers implications for other countries that are pursuing broadband diffusion strategies.
What if there is No Killer Application? An Exploration of a User-Centric Perspective on Broadband
Authors: Middleton Catherine A.
Published: December 2003

This paper explores user and provider experiences with broadband networks. Drawing on data from an early broadband trial and from recent studies of consumer broadband usage, the validity of the commonly held view that widespread adoption of broadband is dependent upon the development of a killer application is challenged. It is argued that access to broadband can be valuable for users without the provision of a killer application and that the dynamics of broadband development are shifting. As more users become content creators and distributors and as it becomes easier for consumers to establish broadband networks without help from traditional providers, the existing relationships within the broadband industry will change. Broadband researchers and stakeholders in the development of broadband networks are encouraged to explore and understand the implications of these changes, recognizing that there is much to be learned about deploying broadband in ways that will create the broad societal benefits promised by its promoters.
Inspecting Pictures for Information to Verify a Sentence: Eye Movements in General Encoding and in Focused Search
Authors: Underwood Geoffrey , Jebbett Lorraine , Roberts Katharine
Published: December 2003

When we see combinations of text and graphics, such as photographs and their captions in printed media, how do we compare the information in the two components? Two experiments used a sentence–picture verification task in which statements about photographs of natural scenes were read in order to make a true/false decision about the validity of the sentence, and in which eye movements were recorded. In Experiment 1 the sentence and the picture were presented concurrently, and objects and words could be inspected in any order. In Experiment 2 the two components were presented one after the other, either picture first or sentence first. Fixation durations on pictures were characteristically longer than those on sentences in both experiments, and fixations on sentences varied according to whether they were being encoded as abstract propositions or as coreferents of objects depicted in a previously inspected picture. The decision time data present a difficulty for existing models of sentence verification tasks, with an inconsistent pattern of differences between true and false trials.
Global–local dynamics of curriculum policy development: a case‐study from Singapore
Authors: Vidovich Lesley , O’Donoghue Tom
Published: December 2003

Non‐government education is often a highly emotive and frequently irrational area of educational debate, especially when it centres on the degree of government funding and support. Frequently people take fortified positions, being either for or against it, often on political grounds and often without taking into account the cultural contexts and complexities involved. The purpose of this article is to look beyond these confines. It is based on a research project focusing on ‘whole’ curriculum policy at the individual school level in non‐government schools in a variety of English‐speaking countries in the developed world. The article is in three parts. The first part outlines the conceptual framework employed to guide our research project on curriculum policy. The second part presents a case‐study of Chinese High School (CHS) in Singapore. This is an exemplar of the type of case‐study of curriculum policy in non‐government schools being undertaken as part of our research. Also, it is an interesting case in its own right; while the school has developed a global orientation to its curriculum policy and has incorporated ‘the global’ into ‘the local’ extremely rapidly, this curriculum transition has not been without its tensions and costs. The third part of the article offers a discussion of the ‘bigger picture’ implications of the findings.
Evaluation of caspase 1 and sFas serum levels in patients with systemic sclerosis: correlation with lung dysfunction, joint and bone involvement
Authors: Dziankowska-bartkowiak Bozena , Waszczykowska Elzbieta , Zalewska Anna , Sysa-jędrzejowska Anna
Published: December 2003

Recent studies point out at the role of apoptosis disturbances in the development of systemic sclerosis (SSc).

The aim of our study was to examine caspase 1 and sFas serum levels in scleroderma patients and correlate the obtained results with skin involvement and internal organ changes.

We studied 29 patients (14 with limited and 15 with diffuse SSc). The extension of skin involvement was measured using Total Skin Score (TSS). Internal organ involvement was assessed by specialist procedures. Serum caspase 1 and sFas levels were measured by enzyme‐linked immunosorbent assay.

We found correlation between sFas serum level and duration of Raynaud′s phenomenon and TSS; caspase 1 serum level correlated only with TSS. Correlations between caspase 1 and lung dysfunction and sFas levels with joint and bone involvement in SSc patients were also observed.

The obtained results revealed that disturbances of apoptosis might play a role in SSc pathogenesis. Caspase 1 and sFas serum levels correlate with the skin involvement severity, lung dysfunction, joint and bone changes.
Oxidative and adhesive responses of human neutrophils to nitrovasodilators in vitro: the role of protein kinases
Authors: Klink Magdalena , Tchorzewski Henryk , Sulowska Zofia
Published: December 2003

Background: Sodium nitroprusside (SNP) and molsidomine are used in the treatment of coronary heart disease. Since the neutrophils play a pathological role in ischaemic heart disease, it is important to understand the direct action of nitrovasodilators on their function.

Aim: We examined the effects of SNP and 3‐morpholinosydnonimine (SIN‐1, molsidomine metabolite) on the respiratory burst of human neutrophils and their adhesion sin vitro. The influence of nitric oxide (NO) donors on the activity of protein kinases, which are involved in the NADPH oxidase activation, was also investigated.

Methods: The respiratory burst of neutrophils was determined by chemiluminescence and fluorescence methods, while the adhesion was assayed by adherence of neutrophils to the plastic surface.

Results: NO donors decreased the oxidative burst of activated neutrophils. However, the effects of SNP and SIN‐1 strongly depended on the treatment time of neutrophils and on the stimulus employed to cells activation. Protein kinase C inhibitor did not prevent the inhibitory effect of SIN‐1, but diminished the inhibitory effect of SNP on the neutrophils′ respiratory burst. Protein tyrosine kinase inhibitor did not affect the action of SNP, but diminished the inhibitory effect of SIN‐1 on fMLP‐stimulated but not on PMA‐stimulated oxidative burst of neutrophils. This suggests that SNP action is mainly associated with protein kinase C, while SIN‐1 is associated with protein tyrosine kinase activity. We also found that SIN‐1 but not SNP diminished the adhesive activity of neutrophils.

Conclusions: Our data show that SIN‐1 biological effect on some neutrophils activity is different from both spermine NONOate and SNP, and mainly depends on ONOO−, while SNP action is mediated by NO.
Role of soluble gp130 in the tumour necrosis factor‐α expression and its production by peripheral blood mononuclear cells
Authors: Jablonskaca E. , Puzewska W. , Marcinczyk M. , Jablonski J.
Published: December 2003

Background: In our previous study we found that rhsIL‐6R, along with recombinant human interleukin‐6, plays a regulatory role in the immune response by modulating the tumour necrosis factor‐α (TNF‐α) expression and its production by peripheral blood mononuclearcells (PBMC). We also suggested that sIL‐6R with IL‐6 secreted by human PMN (neutrophils) influenced the TNF‐α expression and its production by autologous PBMC.

Aims: Since soluble gp130 (sgp130) is a natural inhibitor for sIL‐6R/interleukin‐6 responses, in the present study we estimated an effect of exogenous recombinant human sgp130 and sgp130 secreted by PMN on the TNF‐α expression and its production by PBMC.

Methods: Cells were isolated from whole blood of healthy persons. The PMN were cultured in 96‐well plates for 1 h at 37°C in a humidified incubator with 5% CO2. After the incubation, the culture supernatant of PMN was removed and added to the PBMC. PBMC were incubated for 1 h at 37°C in the same conditions. Cytoplasmic protein fractions of PMN and, for comparative purpose of PBMC, were analysed for presence of sgp130 by western blotting with the use of monoclonal antibody capable of detecting this protein. In the culture supernatants of PMN we examined the concentrations of sgp130 by human enzyme‐linked immunosorbent assay. TNF‐α was measured at the protein levels as well as the mRNA levels.

Results and conclusions:The present results revealed that exogenous recombinant human sgp130 modulates the TNF‐α expression and production by PBMC. In contrast, we did not find any effect of sgp130 secreted by PMN on the TNF‐α expression and its production by autologous PBMC.