bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Ca(Ce) doping on thermopower of LaMnO3 manganites
Authors: Varshney D. , Mansuri I. , Yogi A.
Published: September 2010

To explain the thermoelectric effects of La0.8Ca0.2MnO3 and La0.8Ce0.2MnO3 polycrystalline samples and to find the role of the scattering mechanism a systematic investigation of the thermopower S(T) in the metallic phase has been undertaken. In the relaxation time approximation it is noticed that the phonon drag S(T) with scattering of phonons from defects, grain boundaries, phonons and charge carriers in these samples are effective in the metallic regime. Subsequently, the Mott expression is employed to incorporate the carrier diffusive thermopower. The temperature dependence S(T) is determined by the competition among several operating scattering mechanisms for heat carriers and the balance between carrier diffusion and phonon drag contributions in polycrystalline samples of La0.8Ca0.2MnO3 and La0.8Ce0.2MnO3.
IR active vibrations of a TbFe3(BO3)4 crystal
Authors: Pashchenko M. I. , Bedarev V. A. , Kut’ko V. I. , Besmaternykh L. N. , Temerov V. L.
Published: September 2010

The IR reflection spectra of a TbFe3(BO3)4 crystal are measured in the spectral range 200–2000cm−1 in E⊥c polarization at temperatures 10 and 300K. The reflection spectrum so obtained is analyzed and its interpretation is given on the basis of the internal vibrations of the ionic complexes BO33−, FeO69−, and TbO69− of the TbFe3(BO3)4 crystal. Davydov splitting on the internal vibrational modes at a structural phase transition, which is accompanied by multiplication of the unit cell, was not observed in the experimental spectral range. This is due to the localization of the vibrations of the ionic complexes BO33−, FeO69−, and TbO69− of the TbFe3(BO3)4 crystal.
Communication: Effective spectroscopic Hamiltonian for multiple minima with above barrier motion: Isomerization in HO2
Authors: Barnes George L. , Kellman Michael E.
Published: September 2010

We present a two-dimensional potential surface for the isomerization in the hydroperoxyl radical HO2 and calculate the vibrational spectrum. We then show that a simple effective spectroscopic fitting Hamiltonian is capable of reproducing large scale vibrational spectral structure above the isomerization barrier. Polyad breaking with multiple resonances is necessary to adequately describe the spectral features of the system. Insight into the dynamical nature of isomerization related to the effective Hamiltonian is gained through classical trajectories on the model potential. Contrary to physical intuition, the bend mode is not a “reaction mode,” but rather isomerization requires excitation in both stretch and bend. The dynamics reveals a Farey tree formed from the 2:1 and 3:1 resonances, corresponding to the resonance coupling terms in the effective Hamiltonian, with the prominent 5:2 (2:1+3:1) feature dividing the tree into parts that we call the 3:1 and 2:1 portions.
Freezing and quantization of current passing through a doubly connected superconductor with a point contact
Authors: Koverya V. P. , Bondarenko S. I. , Krevsun A. V. , Levchenko N. M. , Bondarenko I. S.
Published: September 2010

The particulars of dc current passage through a structure consisting of a doubly connected superconductor (DCS) with branches that are asymmetric with respect to length and critical current have been investigated experimentally. The short branch, which has the lowest critical current, was a clamping niobium-niobium point contact with length comparable to the coherence length of the superconductor. In contrast to a previously studied DCS with a short branch much longer than the coherence length, it was found that when the short-branch current reaches the critical value the currents in the branches of the DCS do not undergo self-excited oscillations; a current exceeding the critical value enters the long branch when this current is increased in portions (is quantized), and when it is subsequently decreased it freezes partially or completely in the DCS circuit.
Feedback control of the vortex-shedding instability based on sensitivity analysis
Authors: Camarri Simone , Iollo Angelo
Published: September 2010

In the present work, a simple proportional feedback control is designed to suppress the vortex-shedding instability in the wake of a prototype bluff-body flow, i.e., the flow around a square cylinder confined in a channel with an incoming Poiseuille flow. Actuation is provided by two jets localized on the cylinder surface and velocity sensors are used for feedback control. This particular configuration is a pretext to propose a more general strategy for designing a controller, which is independent of the type of actuation and sensors. The method is based on the linear stability analysis of the flow, carried out on the unstable steady solution of the equations, which is also the target flow of the control. The idea is to use sensitivity analysis to predict the displacement in the complex plane of some selected eigenvalues, found by the linear stability analysis of the flow, as a function of the control design parameters. In this paper, it is shown that the information provided by only sensitivity analysis carried out on the uncontrolled system is not sufficient to design a controller which stabilizes the flow. Therefore, the control is designed iteratively by successive linearizations. Apart from possible constraints, the position of the sensors, the direction along which velocity is measured, and the feedback coefficients are outputs of the design procedure. The proposed strategy leads to a successful control up to a Reynolds number which is at least twice as large as the critical one for the primary instability, using only one velocity sensor.
Electric properties of metallic nanowires obtained in quantum vortices of superfluid helium
Authors: Gordon E. B. , Karabulin A. V. , Matyushenko V. I. , Sizov V. D. , Khodos I. I.
Published: September 2010

Laser ablation of metals in superfluid helium has been used to obtain nickel, indium, and lead nanowire bundles. Wires 5–8nm in diameter demonstrate metallic conductivity and are coupled with one another by point contacts. It is shown that the wire bundles attach to sharp tips introduced into the region of condensation and are up to 1cm long. The high intensity and low threshold of electron field emission are explained by the smallness of the radius of individual wires and the long length of a bundle. The superconducting transition temperature is shifted downwards by 2.9K in lead nanowires and upwards by more than 1K in indium nanowires.
Vortex decay in the Kármán eddy street
Authors: Ponta Fernando L.
Published: September 2010

In this paper, we analyze the effect of viscosity on the vorticity distribution and its rate of decay in the Kármán vortex street behind a circular cylinder. We used direct numerical simulation data, which we compare to well-known experimental measurements. By decomposing the incompressible velocity field in a frame of reference attached to the cylinder into its solenoidal and harmonic components, we identify the eddy structures associated with the formation, shedding, and rearrangement of the vortices into the Kármán street, and study their subsequent decay. This allows us to extend the conclusions of the partially viscous model by Hooker [“On the action of viscosity in increasing the spacing ratio of a vortex street,” Proc. R. Soc. London, Ser. A 154, 67 (1936)], who made several simplifying hypotheses: initial infinite-length filament-vortex wake, circular Lamb vortices of equal age at subsequent times, and no overlapping of the vortex cores. We show that the vortices have elliptical cores with an elliptical ratio that evolves downstream according to a systematic law. We also find that the vortex cores exhibit a Gaussian vorticity profile and a vorticity versus stream-function scatter plot clearly consistent with the Lamb-vortex model. The peak vorticity in the core decays downstream with a hyperbolic decay rate determined by the amount of circulation contained in the core at the early stages of the street, which is also consistent with Lamb’s solution.
Observations of the long distance exploding wire restrike mechanism
Authors: Sinton Rowan , van Herel Ryan , Enright Wade , Bodger Pat
Published: September 2010

An exploding wire restrike mechanism is applied to create plasma paths up to 9 m in length. The mechanism uses enameled copper wires in a 5 to 10 kV/m region of average electric field (AEF). This relatively low AEF restrike mechanism appears to be linked to the formation of plasma beads along the wire’s length. Voltage traces, measurement of relative emitted light intensity and photographs are presented at AEFs below, inside and above the identified restrike region.
Temperature-dependent H2 gas-sensing properties of fabricated Pd nanowires using highly oriented pyrolytic graphite
Authors: Şennik Erdem , Kılınç Necmettin , Öztürk Zafer Ziya
Published: September 2010

Horizontal palladium (Pd) nanowires and Pd nanoparticles were successfully fabricated directly on highly oriented pyrolytic graphite depending on the electrodeposition time using palladium nitrate [Pd(NO2)3] solution at room temperature, and the temperature-dependent hydrogen (H2) sensing properties of these structures were investigated in the concentration range of 50–5000 ppm. Pd nanowires and Pd nanoparticles were fabricated on a graphite surface by applying triple-pulsed potential with varying the electrodeposition time from 400 to 600 s. The fabricated Pd nanowires were characterized by scanning electron microscopy and energy-dispersive x-ray spectroscopy. It was found that the nanowire arrays were continuous, parallel to each other and ordered after an electrodeposition time of 600 s. The diameters of the Pd nanowires and Pd nanoparticles are observed in the range of 70–180 nm. The H2 sensing properties of these structures were determined with variation in resistance measurements. It was observed that the limit of detection is lower than 50 ppm H2, the sensor response was approximately 2% for 1000 ppm H2 at room temperature, and the sensor response was decreased with increasing temperature.
Multicarrier transport in epitaxial multilayer graphene
Authors: Lin Yu-Ming , Dimitrakopoulos Christos , Farmer Damon B. , Han Shu-Jen , Wu Yanqing , Zhu Wenjuan , Gaskill D. Kurt , Tedesco Joseph L. , Myers-Ward Rachael L. , Eddy Charles R. , Grill Alfred , Avouris Phaedon
Published: September 2010

Variable-field Hall measurements were performed on epitaxial graphene grown on Si-face and C-face SiC. The carrier transport involves essentially a single-type of carrier in few-layer graphene, regardless of SiC face. However, in multilayer graphene (MLG) grown on C-face SiC, the Hall measurements indicated the existence of several groups of carriers with distinct mobilities. Electrical transport in MLG can be properly described by invoking three independent conduction channels in parallel. Two of these are n- and p-type, while the third involves nearly intrinsic graphene. The carriers in this lightly doped channel have significantly higher mobilities than the other two.
Magnetoelectric effects in ferromagnetic cobalt/ferroelectric copolymer multilayer films
Authors: Mardana A. , Bai Mengjun , Baruth A. , Ducharme Stephen , Adenwalla S.
Published: September 2010

Interactions between a ferromagnet, cobalt, and a ferroelectric copolymer, poly(vinylidene fluoride with trifluoroethylene) in thin film heterostructures result in a 5% change in the ferroelectric polarization on application of a perpendicular 6 kG magnetic field corresponding to a magnetoelectric coupling coefficient of α=5.45 V/cm Oe. The effect disappears on magnetic saturation, ruling out conventional strain coupling. A simple model posits that the ferroelectric film develops in-plane strain gradients, a consequence of the coupling to strain gradients present at the domain walls in the multidomain Co layer, resulting in the measured polarization change via the flexoelectric effect.
Effect of crystal-field split-off hole and heavy-hole bands crossover on gain characteristics of high Al-content AlGaN quantum well lasers
Authors: Zhang Jing , Zhao Hongping , Tansu Nelson
Published: September 2010

The optical gain characteristics of high Al-content AlGaN quantum wells (QWs) are analyzed for deep UV lasers. The effect of crystal-field split-off hole (CH) and heavy-hole (HH) bands crossover on the gain characteristics of AlGaN QW with AlN barriers is analyzed. Attributing to the strong transition between conduction–CH bands, the TM spontaneous emission recombination rate is enhanced significantly for high Al-content AlGaN QWs. Large TM-polarized material gain is shown as achievable for high Al-content AlGaN QWs, which indicates the feasibility of TM lasing for lasers emitting at ∼220–230 nm.
Negative, positive, and infinite mass properties of a rotating electron beam
Authors: French David M. , Hoff Brad W. , Lau Y. Y. , Gilgenbach R. M.
Published: September 2010

An electron rotating under a uniform axial magnetic field and a radial electric field exhibits an effective mass that may be negative, positive, or infinite, in response to an azimuthal electric field. This paper reports simulation results that show instability and stability when the effective mass are negative and positive, respectively, depending on the magnitude and orientation of the radial electric field. Thus, the inverted magnetron would have a much faster startup than the conventional magnetron, an important consideration for pulsed operation. When the effective mass is infinite, the electrons hardly respond to an azimuthal ac electric field.
Synthesis and magnetic properties of nanocrystals of cubic defect spinel MgMnO3
Authors: Seehra M. S. , Singh V. , Thota S. , Prasad B. , Kumar J.
Published: September 2010

Synthesis and magnetic properties of nanocrystals (size ≃22 nm) of cubic spinel MgMnO3 with the defect structure [Mg2+][Mg1/32+Mn4/34+◻1/3]O4 are reported. Analysis of the magnetization M versus T (2–370 K) and M versus H (up to 65 kOe) data shows a blocking temperature TB≃11 K and an estimated Néel temperature TN∼150 K above which the Weiss temperature θ=−7 K and μ=3.91 μB/Mn4+. For TB<T<TN, fit of the M versus H data to modified Langevin function yields 35 μB as magnetic moment/particle, resulting from the defect structure.
Evaporation temperature-tuned physical vapor deposition growth engineering of one-dimensional non-Fermi liquid tetrathiofulvalene tetracyanoquinodimethane thin films
Authors: Sarkar I. , Laux M. , Demokritova J. , Ruffing A. , Mathias S. , Wei J. , Solovyeva V. , Rudloff M. , Naghavi S. S. , Felser C. , Huth M. , Aeschlimann M.
Published: September 2010

We describe the growth of high quality tetrathiofulvalene tetracyanoquinodimethane (TTF-TCNQ) organic charge-transfer thin films which show a clear non-Fermi liquid behavior. Temperature dependent angle resolved photoemission spectroscopy and electronic structure calculations show that the growth of TTF-TCNQ films is accompanied by the unfavorable presence of neutral TTF and TCNQ molecules. The quality of the films can be controlled by tuning the evaporation temperature of the precursor in physical vapor deposition method.
Influence of slanted nanostripe edges on the dynamics of magnetic domain walls
Authors: Glathe S. , Zeisberger M. , Mattheis R. , Hesse D.
Published: September 2010

We report a combined experimental and theoretical study on the influence of slanted nanostripe edges on the magnetic domain wall (DW) dynamics in permalloy nanostripes. The DWs show a significantly different behavior in the same sample depending on the magnetization configuration in the DW. We explain these characteristics via a difference of the stray field generated by the out-of-plane magnetization inside the DW in the nanostripe edge region during DW motion.
Spectral analysis of resonance ultrasonic spectroscopy: Kramers–Kronig analysis, Fano profiles, and the case of precursor softening in SnTe:Cr
Authors: Safarik D. J. , Salje E. K. H. , Lashley J. C.
Published: September 2010

The analysis of resonant ultrasound spectroscopy (RUS) spectra is exemplified by the study of elastic softening in single-crystal Sn0.995Cr0.005Te near the ferroelastic phase transition at T≃100 K. Kramers–Kronig analysis of the resonance peaks shows that the elastic response is linear over the entire temperature range. In the paraelastic phase the Cole–Cole plots of the RUS spectra are circles with small gaps that are related to linear damping. In the ferroelastic phase strong coupling with domain boundary movement occurs, and results in distortion of the Cole–Cole circles. The RUS line profiles in the ferroelastic phase are well-described by the sum of a resonance term and a Fano spectrum with a Fano parameter of q=0.46. The general equations and some simple approximations, which can conveniently be used to analyze RUS spectra, are summarized. We expect that this analysis is transportable to a large parameter space and can be applied to most RUS spectra for both ferroic and nonferroic materials.
Planar polar liquid crystalline alignment in nanostructured porous silicon one-dimensional photonic crystals
Authors: Mor Shahar , Torres-Costa Vicente , Martín-Palma Raúl J. , Abdulhalim I.
Published: September 2010

The ability of liquid crystals (LCs) to flow and fill nanopores assists in using them for infiltration into porous nanophotonic structures such as nanostructured porous silicon (nanoPS). The reflectivity spectra at normal incidence from periodic nanostructured nanoPS filters infiltrated with nematic LC is found to exhibit polarization dependence. This is experimental evidence that the LC molecules in the nanoPS matrix are aligned such that an effective anisotropy exists parallel to the substrate plane. From the theoretical fit the preferred configuration was found to be the planar-polar geometry which is shown to be biaxial.
Laser-induced scanning tunneling microscopy: Linear excitation of the junction plasmon
Authors: Lee Joonhee , Perdue Shawn M. , Whitmore Desiré , Apkarian V. Ara
Published: September 2010

We introduce the cross-polarized double-beat method for localized excitation of the junction plasmon of a scanning tunneling microscope with femtosecond laser pulses. We use two pulse trains derived from a Ti:sapphire laser operating at a repetition frequency of fs=76 MHz, with a relative shift between their carrier frequencies ωa/2π=fs+fb controlled with an acousto-optic modulator. The trains are cross-polarized and collinearly focused on the junction, ensuring constant radiation flux. The anisotropic susceptibility of the junction plasmon mixes the fields, which modulate the tunneling current at fb (the difference between carrier beat and repetition frequency) at base-band frequencies that can be used for direct detection of the tunneling current. The interferometric cross-correlation of the pulses and the polarization dependence of the mixing identify the coupling to the radiation to be through the coherent z-displacement of the tip plasmon. Single Ag atoms are used to demonstrate microscopy under irradiation. In the linear coupling regime, the laser-induced displacement of the plasmon is operationally indistinguishable from the mechanical displacement of the junction gap.
The decline of a large yellow-footed rock-wallaby (Petrogale xanthopus) colony following a pulse of resource abundance
Authors: Sharp Andy , McCallum Hamish
Published: September 2010

The dynamics of a yellow-footed rock-wallaby (Petrogale xanthopus) colony in central-western Queensland were monitored between spring 1991 and winter 1994. The two years immediately before the study witnessed well above average rainfall, while average rainfall was recorded during the period of the study. Both trapping and standardised visual survey data were modelled using the Jolly–Seber–Cormack (JSC) mark–recapture estimator and the Minta–Mangel (MM) mark–resight estimator. The JSC population estimates were considerably lower than those derived from the MM estimator, indicating that the trapping program sampled only a portion of the total population. Nevertheless, a strong degree of correlation existed between both estimators, suggesting that the dynamics of the trappable subpopulation mirrored those of the total population. The colony declined markedly in size throughout the study (103 to 48 individuals, winter 1992 to winter 1994, JSC estimates; 175 to 116 individuals, summer 1993 to winter 1994, MM estimates). No significant correlations (P > 0.05) were found between seasonal and/or biannual exponential rates of population increase (r) and environmental variables. Nevertheless, a strong positive correlation was observed between biannual r and short-term rainfall (r = 0.90) and pasture conditions (r = 0.85–0.93), suggesting that the colony was influenced to some extent by fluctuations in available resources. Annual r was calculated at –0.29 (1992–93) and –0.49 (1993–94). The marked reduction in colony size suggested that it was declining towards its average carrying capacity, following a strong pulse of recruitment linked to the above-average rainfalls of 1990.
The behaviour and environmental enrichment of captive mahogany gliders (Petaurus gracilis)
Authors: Muller Tracy L. , Ensabella Traza J. , Booth Rosie , Johnston Stephen D. , Phillips Clive J. C.
Published: September 2010

The mahogany glider is an endangered native marsupial of northern Queensland, Australia. A captive population of seven females and three males was established under a recovery plan for this species to provide progeny for release into the wild. This study aimed to investigate the behaviour of mixed-sex and all-female pairs in this population and determine whether behaviour useful for survival in the wild could be stimulated by environmental-enrichment programs. Gliders spent 56% of their time in their nest box and were essentially nocturnal, except for emerging at 1300 hours when food was offered. They were unresponsive to enrichment programs designed to encourage climbing and play, but increased foraging in response to enrichments designed to stimulate feeding behaviour and increase safety from predators. Females kept in same-sex pairs spent more time climbing than those in mixed-sex pairs. In the latter, males spent more time than females stationary and staring, suggesting vigilance, with less active time outside the nest box. Paternal nurturing behaviour was observed for the first time in this species, and this suggests a dominant caring role for males in this species. Copulation was also observed for the first time, but there was no evidence of courtship. It is concluded that the enrichments designed to stimulate foraging activity were successful, and that males played a major role in the rearing of young in this species, which needs to be recognised in managing captive populations.
Prevalence of threatened native species in canid scats from coastal and near-coastal landscapes in south-eastern Australia
Authors: Claridge Andrew W. , Mills Douglas J. , Barry Simon C.
Published: September 2010

Predator scat analysis was used to infer the potential impact of wild dogs (Canis lupus dingo, C. l. familiaris and hybrids of the two) on threatened native terrestrial mammals in coastal and near-coastal southern New South Wales, Australia. Prey items recorded in wild dog scats were compared with those occurring in scats of the red fox collected at the same study sites. Six threatened mammal species were recorded in either wild dog or fox scats: eastern pygmy possum, grey-headed flying fox, long-nosed potoroo, southern brown bandicoot, white-footed dunnart and yellow-bellied glider. The prevalence of these threatened species in fox scats was significantly higher than in wild dog scats. Otherwise, wild dogs mostly consumed larger prey items such as swamp wallabies and wombats whereas foxes more heavily preyed on small mammals such as antechinus and rats. Our results suggest that foxes are the major threat to threatened mammal species in the study region. Land management agencies in south-eastern mainland Australia should therefore focus on controlling foxes for biodiversity gain.
The diet of some New Guinean dasyurid marsupials
Authors: Grossek G. L. , Woolley P. A. , Menzies J. I.
Published: September 2010

We investigated the diets of five forest-dwelling species of dasyurid marsupials endemic to New Guinea by using faecal and gut content analysis and compared the contents with the results of pitfall trapping for terrestrial invertebrates carried out coincidently. In one study area, in montane forest 2060–2340 m above sea level, three dasyurid species were trapped. In another area, in forest 1000–1470 m above sea level, two other species were captured. All five species ate a diverse range of invertebrates but beetles (Coleoptera) and spiders (Araneae) formed the bulk of their diet, followed by grasshoppers and crickets (Orthoptera). Earthworms (Annelida) were eaten by all species and some vertebrate remains were found in samples from four species. We found some significant differences between diets of the sympatric species. Some of the invertebrates commonly collected in pitfall traps, such as isopods (Isopoda) and amphipods (Amphipoda), were rarely detected in the diets of any of the species and millipedes (Diplopoda) and centipedes (Chilopoda) were never detected. Our results are broadly in agreement with what is known about the diets of the small Australian species of dasyurid marsupials.
Gross renal morphology of the numbat (Myrmecobius fasciatus) (Marsupialia:Myrmecobiidae)
Authors: Cooper C. E. , Withers P. C.
Published: September 2010

There is a strong correlation between the structure of the mammalian kidney and its urinary concentrating ability. We examine here the kidney of an endangered termitivorous marsupial (Myrmecobius fasciatus) and use the measured kidney morphometrics to calculate maximal urinary concentration. The relative medullary area (1.34) of the kidney of M. fasciatus is typical of other dasyuromorph marsupials, as is its predicted maximal urinary concentration of 3617 mOsm kg–1 H2O, despite its historically semiarid/arid distribution. The termitivorous diet of M. fasciatus presumably provides it with sufficient water to limit selection for a high urinary concentrating capacity.
The Zadko Telescope: A Southern Hemisphere Telescope for Optical Transient Searches, Multi-Messenger Astronomy and Education
Authors: Coward D. M. , Todd M. , Vaalsta T. P. , Laas-Bourez M. , Klotz A. , Imerito A. , Yan L. , Luckas P. , Fletcher A. B. , Zadnik M. G. , Burman R. R. , Blair D. G. , Zadko J. , Boër M. , Thierry P. , Howell E. J. , Gordon S. , Ahmat A. , Moore J. A. , Frost K.
Published: September 2010

The new 1 m f/4 fast-slew Zadko Telescope was installed in June 2008 about 70 km north of Perth, Western Australia. It is the only metre-class optical facility at this southern latitude between the east coast of Australia and South Africa, and can rapidly image optical transients at a longitude not monitored by other similar facilities. We report on first imaging tests of a pilot program of minor planet searches, and Target of Opportunity observations triggered by the Swift satellite. In 12 months, 6 gamma-ray burst afterglows were detected, with estimated magnitudes; two of them, GRB 090205 (z = 4.65) and GRB 090516 (z = 4.11), are among the most distant optical transients imaged by an Australian telescope. Many asteroids were observed in a systematic 3-month search. In September 2009, an automatic telescope control system was installed, which will be used to link the facility to a global robotic telescope network; future targets will include fast optical transients triggered by high-energy satellites, radio transient detections, and LIGO gravitational wave candidate events. We also outline the importance of the facility as a potential tool for education, training, and public outreach.
Galaxy Metabolism
Authors: Hopkins Andrew
Published: September 2010

‘Galaxy Metabolism' was the second in the annual ‘Southern Cross Astrophysics Conference Series’ (http://www.aao.gov.au/AAO/southerncross/), supported by the Anglo-Australian Observatory and the Australia Telescope National Facility. It was held at the Australian National Maritime Museum in Darling Harbour, Sydney, from 22 to 26 June 2009, and was attended by 91 delegates from around the world.

Over the past decade, both the star formation history and stellar mass density in galaxies spanning most of cosmic history have been well constrained. This provides the backdrop and framework within which many detailed investigations of galaxy growth are now placed. The mass-dependent and environment-dependent evolution of galaxies over cosmic history is now the focus of several surveys. Many studies are also exploring the role of gas infall and outflow in driving galaxy evolution, and the connection of these processes to massive star formation within galaxies.

The aims of ‘Galaxy Metabolism’ were to bring together the global constraints on galaxy evolution, at both low and high redshift, with detailed studies of well-resolved systems, to define a clear picture of our understanding of galaxy metabolism: How do the processes of ingestion (infall), digestion (ISM physics, star formation) and excretion (outflow) govern the global properties of galaxies; how do these change over a galaxy's lifetime; and are the constraints from nearby well resolved studies consistent with those from large population surveys at low and high redshift?

The conference was a great success, with an extensive variety of topics covered spanning many aspects of galaxy evolution, and brought together eloquently in a comprehensive conference summary by Warrick Couch. The four papers by De Lucia (2010), Cole (2010), Vlajić (2010) and Stocke et al. (2010) presented in this special collection of PASA are just a sampling of the depth and variety of the resentations given during the conference.
Host density drives the postglacial migration of the tree parasite,
Epifagus virginiana
Authors: Tsai Yi-Hsin Erica , Manos Paul S.
Published: September 2010

To survive changes in climate, successful species shift their geographic ranges to remain in suitable habitats. For parasites and other highly specialized species, distributional changes not only are dictated by climate but can also be engineered by their hosts. The extent of host control on parasite range expansion is revealed through comparisons of host and parasite migration and demographic histories. However, understanding the codistributional history of entire forest communities is complicated by challenges in synthesizing datasets from multiple interacting species of differing datatypes. Here we integrate genetic and fossil pollen datasets from a host–parasite pair; specifically, the population structure of the parasitic plant (
Epifagus virginiana
) was compared with both its host (
Fagus grandifolia
) genetic patterns and abundance data from the paleopollen record of the last 21,000 y. Through tests of phylogeographic structure and spatial linear regression models we find, surprisingly, host range changes had little effect on the parasite's range expansion and instead host density is the main driver of parasite spread. Unlike other symbionts that have been used as proxies to track their host's movements, this parasite's migration routes are incongruent with the host and instead reflect the greater importance of host density in this community's assembly. Furthermore, these results confirm predictions of disease ecological models regarding the role of host density in the spread of pathogens. Due to host density constraints, highly specialized species may have low migration capacities and long lag times before colonization of new areas.
Strategic revisions in the writing of Year 7 students in the UK
Authors: Keen John
Published: September 2010

This article discusses revisions to personal narrative writing made by Year 7 students (aged 11–12) in a UK secondary school. The concept of strategic revision was used as a basis for analysing drafts and revised texts in order to investigate strategies and techniques deployed by students in the process of revision and how these related to expectations student writers had of their readers.

These analyses suggest that, given a reasonably supportive instructional environment, some Year 7 students can revise their own written texts strategically, and that in doing so they may recruit, and perhaps acquire, a range of writing skills and associated procedural knowledge. They also suggest that in the process of revising their texts, some student writers may have altered their expectations of their readers' understanding, ability to interpret and willingness to empathise.

Implications for researching writing processes and for the writing curriculum are suggested, including the use of students' revisions to tap into the complex sets of procedural knowledge which seem to underlie aspects of writing and writing development.
National monitoring in social studies: the reliability of assessment interviews
Authors: Hawe Eleanor , Browne Isabel
Published: September 2010

The National Education Monitoring Project (NEMP) is responsible in New Zealand for the national assessment of primary school children's achievement in the essential learning areas, one of which is social studies. Individual interviews are one of the approaches used to assess students' understanding. The assessors are registered teachers, selected by NEMP, who attend a training week where they learn how to conduct the standardised assessment tasks and associated interviews. This study examines the reliability of the assessment interviews used in the 2005 round of social studies monitoring, in particular the variations between teacher administrators (TAs) in their use of prompts and probes. The extent of variation observed in the use of three kinds of prompt was sufficient to raise questions about the reliability of the assessment process. A surprising outcome was the consistent failure of TAs to clarify and elucidate students' social studies understandings through the judicious use of probes. The prompt‐related variations between TAs and their failure fully to ‘tap into’ understandings assessed by interview‐based tasks are serious threats to the validity of claims regarding students' achievement in social studies. This is particularly concerning as NEMP data are used as the basis for identifying and reporting national patterns and trends in educational performance and making recommendations to policy‐makers, curriculum planners and educators.
Managing school‐based curriculum innovations: a Hong Kong case study
Authors: Law Edmond H.F. , Wan Sally W.Y. , Galton Maurice , Lee John C.K.
Published: September 2010

This study was originally designed to explore the impact of a distributed approach to developing curriculum leadership among schoolteachers. Previous papers have focused on reporting evidence of teacher learning in the process of engaging teachers in various types of curriculum decision‐making in an innovation project based on interview data. This article reports a discourse analysis of the interactions based on the visual data in videotaped meetings between teachers in a Chinese curriculum development team and shows that teacher participation is constrained by the leadership styles of the positional leaders in the team in the second action cycle in the project. The mediational effects of the leadership styles invite policy‐makers and school management to rethink the effectiveness of school‐based approaches to curriculum development in enhancing teacher learning and development.
PAVEd for Success: An Evaluation of a Comprehensive Preliteracy Program for Four-Year-Old Children
Authors: Schwanenflugel Paula J. , Hamilton Claire E. , Neuharth-Pritchett Stacey , Restrepo M. Adelaida , Bradley Barbara A. , Webb Mi-Young
Published: September 2010

The purpose of the study was to evaluate the effectiveness of PAVEd for Success, comprehensive preliteracy program guidelines to support the development of foundational preliteracy skills in 4 year olds. Prekindergarten teachers received professional development on variables of the program that included a summer institute, after-school workshops, and classroom support from preliteracy specialists. Children were assessed at prekindergarten entry, following the implementation period and at the end of the school year. Vocabulary knowledge, phonological awareness, and alphabet knowledge were assessed during the prekindergarten year, and early literacy indicators and early decoding skills were assessed at the end of the kindergarten year. While all experimental variables showed some benefits to the development of children's preliteracy skills, only the full program benefited children who entered the prekindergarten program at risk for reading difficulties. The program participants benefited in early literacy and decoding skills when compared to controls. Implementation by teachers with support and sustainability of program features without support was also evaluated. Teachers were most likely to implement and sustain program features which shared consistency with some prior literacy focus and when they were able to integrate program features across the curriculum. This research suggests that long-term change in the literacy skills of young children will involve complex and multifaceted approaches to preliteracy development.
Reading-Related Literacy Activities of American Adults: Time Spent, Task Types, and Cognitive Skills Used
Authors: White Sheida , Chen Jing , Forsyth Barbara
Published: September 2010

This article presents data on the types and duration of reading-related activities reported by a volunteer sample of 400 adults (demographically similar to the U.S. adult population age 20 and older in terms of race, ethnicity, education, and working status) in the 2005 Real-World Tasks Study. This diary study revealed that adults spent, on average, 4.5 hours a day on activities that involve reading printed and electronic texts, a relatively higher percentage of which occurred on working than on nonworking days. Prose and quantitative tasks were more common (98 and 94 minutes, respectively) than hybrid and document tasks (40 and 25 minutes, respectively). Hybrid tasks constituted 15% of the total daily reading-related literacy time, a novel finding because hybrid tasks have not been defined or included in any previous studies. Most reading-related activities required application skills to act on or use information to function in society and achieve goals (e.g., to decide which health insurance plan to purchase). In terms of texts, adults spent about 191 minutes a day using prose texts but only 116 minutes using document texts. The largest portion of reading-related time of prose texts was spent on periodicals, journals, newspapers, electronic correspondence, and informational texts. Lists accounted for over a fourth of the time spent on activities involving reading document texts. These results have been used in assessment development to ensure that assessment tasks reflect everyday literacy activities. The data may also benefit literacy practitioners in creating materials that reflect adults' daily reading practices.
Thinking Aloud in Expository Text: Processes and Outcomes
Authors: Caldwell JoAnne , Leslie Lauren
Published: September 2010

This study examines three questions: What kinds of think-aloud statements, in particular what kinds of inferences, are made by middle school students while reading expository text? Does thinking aloud affect comprehension as measured by recall and answers to questions? Does thinking aloud add value to the assessment of comprehension beyond what is learned through recall and question answering? Sixty-eight middle-school students read expository texts and thought aloud on one segment and did not think aloud on another segment. After completing each segment, the students recalled the texts and answered comprehension questions. The content of think-alouds and recall was examined using Trabasso and Magliano's (1996a) clausal coding scheme and inferences were differentiated as explanatory, predictive or associative. Students primarily paraphrased the text as they thought aloud and made associative inferences using text information. Thinking aloud was associated with more associative inferences in recall, which correlated negatively with the ability to answer comprehension questions. The content of think-alouds may provide a more sensitive picture of readers' processing than unaided recall or answers to questions.
Regional aquatic ecological security assessment in Jinan, China
Authors: Hong Qian , Meng Qingbin , Wang Pei , Wang Hongyuan , Liu Ruimin
Published: September 2010

Regional aquatic ecological security is an important indicator that presents the aquatic ecological state and can guide the aquatic environmental management. Here, an index system for the regional aquatic ecological security assessment was established based on the Pressure-State-Response Model and analytical hierarchy process. The system was applied in the city of Jinan in eastern China. The results indicated that the state of the aquatic ecological security is best in Changqing District which has relatively high vegetation coverage, a well-conserved ecological condition and a relatively smaller population density than other districts. Following were Lixia, Shizhong, Huaiyin, and Licheng Districts. The state of the aquatic ecological security is the poorest in Tianqiao District, mainly due to its over-exploitation of groundwater, declining landscape diversity and lower scientific and technical investment. The driving force test also demonstrated that economic development and population size are the dominant impact factors for the variation of aquatic ecological security. Environmental protection investment should be paid more attention as an important measure to improve the aquatic ecological security in Jinan. It was demonstrated that the index system can be effectively applied in an aquatic ecological security assessment to identify the primary impact factors that support decision-making on water resources management.
Development of co-management in the Inland Fisheries in Sri Lanka: Case studies of Senenayake Samudra and Mahavilachchiya Reservoirs
Authors: Kulatilake M. , Liyanage H.S.W.A. , Fernando W.M.J.R. , Chandrasoma J. , Van der Knaap M.
Published: September 2010

The Aquatic Resource Development and Quality Improvement Project in Sri Lanka conducted the first country-wide survey of the inland fisheries, with emphasis on reservoirs. The same project also introduced a form of co-management on selected reservoirs, which would assure sustainable management of the fisheries and which are regularly enhanced by stocking of fingerlings from aquaculture centers. A comparison is made between two reservoirs including all management tools that are available and used for its fisheries. Results from the case studies could be applied to other reservoirs throughout the island also.
Ubiquitous omnivory, functional redundancy and the resiliency of Lake Victoria fish community
Authors: Ojwang W. Oweke , Ojuok J. E. , Mbabazi D. , Kaufman L.
Published: September 2010

The fish community of Lake Victoria, East Africa, has continued to exhibit an intriguing degree of resiliency despite stress from anthropogenic activities. Frequent environmental perturbations include wild fluctuations in fishing pressure, limnological conditions, and lake levels. Surprisingly, many of the endemic and other indigenous fishes have survived, and some have even increased in numbers in recent years. While a positive development, this resiliency is a red flag to scientists because we do not understand it, or know whether it can be expected to continue. Furthermore, besides issues of immediate human well-being, there remain grave concerns about long term resource sustainability. This paper explores possible reasons for ecological resilience in the Lake Victoria fish community, with a focus on omnivory and functional redundancy as possible explanations. The analysis used published data based on both traditional gut content analysis (GCA) and stable isotope analysis (SIA). Trophic plasticity is ubiquitous among the surviving fishes of Lake Victoria. This, combined with an overall simplification of the food web, contributed to the lake community's current resilience.
Lake Malawi: fishes, fisheries, biodiversity, health and habitat
Authors: Weyl Olaf L. F. , Ribbink Anthony J. , Tweddle Denis
Published: September 2010

Lake Malawi's fishes are a source of food for millions and provide a livelihood for thousands by encouraging tourism, fascinating the scientific fraternity, enchanting aquarists around the world and maintaining ecosystem processes in the lake. From a fisheries and resource assessment perspective, the region is data-poor, but there is sufficient peer-reviewed and grey literature on the limnology, fisheries and ichthyofauna of the lake to provide a good overview of the state of the fishery. There are signs of over exploitation and an increasing fishing effort has resulted in decreased catch rates, depletion of larger, more valuable species in the fishery and species changes. The fishery is harvesting stocks that were formerly thought to be under exploited. Previous attempts to manage the fishery have been ineffective and long term strategies addressing overfishing will need to transform the fishery from an open-access to a limited access system. As important as direct intervention in the management of the fisheries, will be the management of catchment processes. Increased nutrient inputs; changes to the phytoplankton composition; sediment loading; nearshore water quality impacts and changing water levels threaten the ecosystem. Introduction of alien invasive organisms is an ever present threat to the ecosystem as well, due to continued development of small scale aquaculture in the region. The overriding causative factor for all these effects is the poverty of the lakeshore communities which do not have the economic privilege of being able to adapt their utilisation patterns.
Minor water bodies around southern Lake Victoria—a replica of lost biodiversity
Authors: Katunzi E. F. B. , Mbonde A. , Waya R. , Mrosso H. D. J.
Published: September 2010

The catchment and water chemistry of Lake Victoria are greatly influenced by the inflow of rivers and the alternation of the dry and wet seasons. The ecological integrity of the lake has been altered as a result of changes in its physical, chemical, and biological properties resulting from natural and anthropogenic forces. With human population growth, there has been an increase in the multiplicity of activities in the lake basin rendering the lake environmentally unstable.

The diversity of the fauna, especially of fish and of the flora declined and the health of the ecosystem deteriorated due to excessive fishing pressure, predation, and competition among introduced species, wetland degradation, poor watershed management and pollution. The nutrient content in Lake Victoria has increased and the consequent eutrophication had a big impact on the biodiversity of the cichlids.

Factors that had been affecting Lake Victoria had not impacted the small water bodies in the basin on the same scale. There are several pockets of rare and even extinct species in Lake Victoria that still survive in several ox-bow lakes associated with the extensive wetlands around Lake Victoria. The phytoplankton, zooplankton and fish communities known to be missing in the main lake continued to survive in these minor water bodies. Species still occurring in both habitats exhibit different levels of tolerance to exploitation levels. However, there is no clear policy to conserve the minor water habitats. The paper compares the common taxa in Lake Victoria and the satellite lakes identifying the rare ones in an attempt to mobilize forces to conserve them.