bluuebunny/crossref_metadata_2025 huggingface dataset:
A bioeconomic optimization approach for rebuilding marine communities: British Columbia case study
Authors: AINSWORTH C. H. , PITCHER T. J.
Published: May 2010

Many marine ecosystems are depleted of living resources as a result of long-term overexploitation. Restoration plans should perhaps consider the entire ecosystem as opposed to single species, yet there is currently no suitable framework available for the design and comparison of whole-ecosystem restoration trajectories. This paper presents a novel addition to Ecopath with Ecosim's policy search routine, the ‘specific biomass’ objective function, which allows gaming scenarios to be run using selective fishing as a tool to rebuild depleted marine ecosystems or modify them into a preferred state. In this paper, restoration scenarios aimed to restore an ecosystem in Northern British Columbia to a state similar to the historic ecosystem of 1950 AD. Restoration plans that achieve restoration quickly tend to require a large sacrifice in fishery profits, while slower plans allow for continued harvest benefits. A convex relationship between profit and recovered biodiversity suggests that there may be an optimal rate of restoration. Cost-benefit analysis demonstrates that conservative restoration plans can offer a rate of return superior to bank interest when viewed as an investment in natural capital. Increasing the selectivity of fishing gear improves the economic outlook.
The Needs of Aging Parents Caring for an Adult with Acquired Brain Injury
Authors: Minnes Patricia , Woodford Lynn , Carlson Peter , Johnston Jane , McColl Mary Ann
Published: May 2010

Cette étude a porté sur des questions d’intérêt pour et au service des besoins des parents plus âgés qui s’occupent d’un fils ou d’une fille adulte avec une lésion cérébrale acquise (LCA) en Ontario. Trois questions ont été identifiées comme particulièrement difficile: le diagnostic de la lésion cérébrale, les sentiments des parents quant à la cause des lésions cérébrales, et le planification d’hébergement à long terme pour leurs membres de familles avec une lésion cérébrale. Les services les plus fréquemment cités pour les besoins d’une personne atteinte de LCA étaient d’ordre social et/ou d’activités de loisirs, programmes de jour, et le placement residentiel. Les services les plus fréquemment cités comme nécessaires par les parents etaient l’éducation des parents et des groupes de soutien. L’information recueillie fournit une base pour d’autres recherches dans d’autres secteurs. Les implications de ces résultats initiaux pour la pratique et la politique clinique et pour le développement du programme sont discutées.
James Madison, Law Student and Demi-Lawyer
Authors: Bilder Mary Sarah
Published: May 2010

We think of James Madison as a political theorist, legislative drafter, and constitutional interpreter. Recent scholarship has fought fiercely over the nature of his political thought. Unlike other important early national leaders—John Adams, Alexander Hamilton, Thomas Jefferson, John Marshall, Edmund Randolph, James Wilson—law has been seen as largely irrelevant to Madison's intellectual biography. Madison, however, studied law and, at least in one extant manuscript, took careful notes. These notes have been missing for over a century, and their loss contributed to the sense that Madison must not have been that interested in law. Now located, these notes reveal Madison's significant grasp of law and his striking curiosity about the problem of language. Madison's interest in interpretation is certainly not news to scholars. These notes, however, help to establish that this interest predated the Constitution and that his interest in constitutional interpretation was an application of a larger interest in language. Moreover, Madison thought about the problem of legal interpretation as astudentof law, never from the secure status oflawyer. Over his lifetime, he advocated a variety of institutional approaches to constitutional interpretation, and this comfort with nonjudicial interpreters, along with a peculiar ambivalence about the proper location of constitutional interpretation, may owe a great deal to his self-perception as a law student but never a lawyer.
CONSIDERING THE TIES THAT BIND: Kinship, marriage, household, and territory among the Maya
Authors: Kintz Ellen R.
Published: May 2010

The meaning of ancient Maya social organization continues to engender heated debate. Hierarchy and heterarchy are suggested as organizational principles that reflect the variability characteristic of the Maya households past and present. The presence or absence of lineage in the core area or hinterland reflects the social dimension of Maya social organization and small and larger households are tied to the larger political structure. Detailed archaeological data have documented extreme economic variability in Maya household patterns and relationships associated with these. Scholars argue that structures contain rich symbolic statements and reflect Maya ideological structure. Discussion of Maya household patterns moves beyond a monolithic understanding of social organization in the past and the present, including extreme variation in kinship and marriage patterns, associated economic structure, power, and symbolic representations that bind the society and tie individuals to higher structural levels.
INTRODUCTION
Authors: Fowler William R. , Hageman Jon B.
Published: May 2010

This issue's Special Section presents recent archaeological research and interpretive perspectives on ancient Maya social organization. This topic has received increasing archaeological attention in recent years, with inferences drawn primarily from settlement studies, excavation data from households, and mortuary patterns complemented by evidence from ethnohistoric sources and ethnographic data and interpretations (Fash 1994:187–188, 190–192).
ENDOGENOUS INEQUALITY OF NATIONS THROUGH FINANCIAL ASSET MARKET INTEGRATION
Authors: Böhm Volker , Vachadze George
Published: May 2010

The paper analyzes an endogenous mechanism leading perfectly symmetric economies to diverge in the long run after unifying their financial asset markets. The standard growth model with overlapping generations of consumers (OLG) is extended to include uncertainty and a financial asset. In the absence of an international asset market, the two autarkic economies converge to the same globally attracting steady state under rational expectations dynamics. When the two asset markets are unified internationally, additional asymmetric steady states appear, implying that the steady state with equal levels of capital becomes unstable, causing symmetry breaking. The paper derives general sufficient conditions for a saddle node bifurcation of the symmetric steady state. A numerical example shows that these effects occur, in particular when the production function and the function of absolute risk aversion are isoelastic.
SECTORAL CHANGES AND THE INCREASE IN WOMEN'S LABOR FORCE PARTICIPATION
Authors: Akbulut Rahşan
Published: May 2010

Throughout the second half of the 20th century, women in the United States decided to move increasingly into the labor market. This paper investigates the growth of the service sector as an explanation for the increase in women's employment. It develops an economic model that can account for the increase in women's employment and the growth of the service sector at the same time. A growth model with two sectors and a home production technology is constructed in order to quantitatively assess the contribution of sectoral productivity differences to the change in women's employment decision. The sectoral productivities are taken from the data. This model demonstrates that a higher rate of productivity growth in market services compared to home services can account for a large fraction of the observed increase in women's labor supply from 1950 to 2005.
Development and Tests of Short Versions of the Youth Psychopathic Traits Inventory and the Youth Psychopathic Traits Inventory-Child Version
Authors: van Baardewijk Yoast , Andershed Henrik , Stegge Hedy , Nilsson Kent W. , Scholte Evert , Vermeiren Robert
Published: May 2010

The adolescent Youth Psychopathic Traits Inventory (YPI) and its child version (YPI-CV) are sound but lengthy instruments for measuring psychopathic traits in youths. The current study develops psychometrically strong short versions of these instruments. Samples used for item reduction were community samples of adolescents (n = 2105, age 16–19, 49% boys) and children (n = 360, age 9–12, 52% boys). Stepwise parallel reduction using principal components analyses and content-related arguments resulted in two highly similar short instruments of 18 items each. In both versions, near identical and theoretically comprehensible three factor structures were demonstrated, which were crossvalidated in independent samples (CFI = .97 and .97; RMSEA = .044 and .038, respectively). Results were similar for boys and girls. The short instruments were reliable (Cronbach’s αs of .85 and .83) and covered all core characteristics of the psychopathic personality construct. The short versions showed a high convergence with the original long instruments (r = .95 and .93, respectively) and similar correlations to external criterion measures of conduct problems. Therefore, the abbreviated versions are practical and valid alternatives for the original YPIs when administration time is limited.
The Spanish Version of the Self-Statements During Public Speaking Scale
Authors: Rivero Raul , Garcia-Lopez LuisJoaquin , Hofmann Stefan G.
Published: May 2010

Contemporary theories of social anxiety emphasize the role of cognitive processes. Although social anxiety disorder is one of the most common mental health problems in adolescents, there are very few self-report instruments available to measure cognitive processes related to social anxiety in adolescents, let alone non-English instruments. The Self-Statements During Public Speaking Scale (SSPS; Hofmann & DiBartolo, 2000 ) is a brief self-report measure designed to assess self-statements related to public speaking, the most commonly feared social performance situation. In order to fill this gap in the literature, we translated the SSPS into Spanish and administered it to 1,694 adolescents from a community sample, a clinical sample composed of 71 subjects with a principal diagnosis of social anxiety disorder, and a clinical control group consisting of 154 patients. The scale showed good psychometric properties, supporting the use of the Spanish version of the SSPS in adolescents.
A Construct Validation of a Profession-Focused Personality Questionnaire (PQ) Versus the FFPI and the SIMP
Authors: Bäccman Charlotte , Carlstedt Berit
Published: May 2010

This study is a construct validation of a profession-focused personality questionnaire (PQ), based on the Big Five, and developed for a military population and military context. The sample (N = 363) consisted of participants selected for international services in the Swedish Armed Forces. The structure of the PQ was modeled by means of confirmatory factor analysis, and its convergent validity was tested against the Five Factor Personality Inventory (FFPI) ( Hendricks, Hofstee, & de Raad, 1999 , 2000 ) and the Single-Item Measures of Personality (SIMP) ( Woods & Hampson, 2005 ) as correlations. The emergent structure of the PQ – 41 items and 7 aspects – showed good internal consistency and acceptable convergent validity with both criterion instruments. The only nonconvergence was found between the Agreeableness aspect of the PQ, Concern for Others, and Agreeableness of the SIMP, most likely because of the broader SIMP factor. The structure of PQ was tested on a new sample (N = 274) and was found stable regarding the factor loadings and the relations between the factors. While the PQ needs to be investigated further, it seems as if it may become a useful tool in the research of military teams and contexts.
Psychometric Properties of the Italian Version of the Utrecht Work Engagement Scale (UWES-9)
Authors: Balducci Cristian , Fraccaroli Franco , Schaufeli Wilmar B.
Published: May 2010

Work engagement may be defined as a positive, fulfilling, work-related psychological state characterized by the dimensions of vigor, dedication, and absorption. In this study, the psychometric properties of the Italian version of the Utrecht Work Engagement Scale (UWES-9) were investigated by using two samples of Italian (n = 668) and Dutch (n = 2213) white-collar employees. In addition to reliability analyses, we also conducted a series of multiple-group confirmatory factor analyses of the UWES-9. The validity of the UWES-9 was investigated by studying its correlations with the Job-Related Affective Well-Being Scale (JAWS) and with a measure of work performance. Results showed that a three-factor solution of the UWES-9 is invariant across the Italian and Dutch samples, with data supporting factor variance and covariance invariance in addition to metric invariance. Internal consistencies of the vigor, dedication, and absorption scales are good. The UWES-9 and its subscales show significant correlations in the expected direction with the JAWS and with work performance. The Italian version of the UWES-9 behaves consistently with its original Dutch version and may be used for future studies of work engagement.
Magnetospheric period oscillations of Saturn's bow shock
Authors: Clarke K. E. , Andrews D. J. , Coates A. J. , Cowley S. W. H. , Masters A.
Published: May 2010

Using magnetic field and plasma electron data from 35 Cassini orbits on which the spacecraft crossed Saturn's magnetopause and bow shock during 2004–2007, we provide first evidence for bow shock oscillations related to oscillations in the magnetic field and plasma inside the magnetosphere near the ∼11 h planetary rotation period, termed here the “magnetospheric period.” Two case studies are presented showing both bow shock and magnetopause oscillations on given spacecraft passes, together with a statistical study showing that bow shock oscillations observed within a timing window between 0.6 and 1.6 of the magnetospheric period are significantly organized by the phase of the interior field oscillations. Both case and statistical studies indicate that the bow shock and magnetopause oscillate approximately in phase, within a phase uncertainty of about ±25°. The phasing of the oscillations is such that the interior oscillatory field within the magnetospheric “core” region (magnetic shells with equatorial crossing distances less than ∼15 Saturn radii) is rotated ∼130°–160° counterclockwise (as viewed from the north) of the instantaneous location of outward boundary excursion maxima. The overall data set suggests that bow shock oscillations are commonly observed over the whole local time range that the spacecraft crossed the boundary (∼5–17 h LT) with typical amplitudes of ∼1–2 RS, comparable to results found previously for the corresponding oscillations of the magnetopause. These results thus reveal a new aspect of Saturn's bow shock dynamics, providing first evidence for modulation of its position by the periodic processes observed throughout Saturn's magnetosphere.
Ground surface deformation patterns, magma supply, and magma storage at Okmok volcano, Alaska, from InSAR analysis: 1. Intereruption deformation, 1997–2008
Authors: Lu Zhong , Dzurisin Daniel , Biggs Juliet , Wicks Charles , McNutt Steve
Published: May 2010

Starting soon after the 1997 eruption at Okmok volcano and continuing until the start of the 2008 eruption, magma accumulated in a storage zone centered ∼3.5 km beneath the caldera floor at a rate that varied with time. A Mogi‐type point pressure source or finite sphere with a radius of 1 km provides an adequate fit to the deformation field portrayed in time‐sequential interferometric synthetic aperture radar images. From the end of the 1997 eruption through summer 2004, magma storage increased by 3.2–4.5 × 107 m3, which corresponds to 75–85% of the magma volume erupted in 1997. Thereafter, the average magma supply rate decreased such that by 10 July 2008, 2 days before the start of the 2008 eruption, magma storage had increased by 3.7–5.2 × 107 m3 or 85–100% of the 1997 eruption volume. We propose that the supply rate decreased in response to the diminishing pressure gradient between the shallow storage zone and a deeper magma source region. Eventually the effects of continuing magma supply and vesiculation of stored magma caused a critical pressure threshold to be exceeded, triggering the 2008 eruption. A similar pattern of initially rapid inflation followed by oscillatory but generally slowing inflation was observed prior to the 1997 eruption. In both cases, withdrawal of magma during the eruptions depressurized the shallow storage zone, causing significant volcano‐wide subsidence and initiating a new intereruption deformation cycle.
Seasonal versus episodic performance evaluation for an Eulerian photochemical air quality model
Authors: Jin Ling , Brown Nancy J. , Harley Robert A. , Bao Jian‐Wen , Michelson Sara A. , Wilczak James M.
Published: May 2010

This study presents detailed evaluation of the seasonal and episodic performance of the Community Multiscale Air Quality (CMAQ) modeling system applied to simulate air quality at a fine grid spacing (4 km horizontal resolution) in central California, where ozone air pollution problems are severe. A rich aerometric database collected during the summer 2000 Central California Ozone Study (CCOS) is used to prepare model inputs and to evaluate meteorological simulations and chemical outputs. We examine both temporal and spatial behaviors of ozone predictions. We highlight synoptically driven high‐ozone events (exemplified by the four intensive operating periods (IOPs)) for evaluating both meteorological inputs and chemical outputs (ozone and its precursors) and compare them to the summer average. For most of the summer days, cross‐domain normalized gross errors are less than 25% for modeled hourly ozone, and normalized biases are between ±15% for both hourly and peak (1 h and 8 h) ozone. The domain‐wide aggregated metrics indicate similar performance between the IOPs and the whole summer with respect to predicted ozone and its precursors. Episode‐to‐episode differences in ozone predictions are more pronounced at a subregional level. The model performs consistently better in the San Joaquin Valley than other air basins, and episodic ozone predictions there are similar to the summer average. Poorer model performance (normalized peak ozone biases <−15% or >15%) is found in the Sacramento Valley and the Bay Area and is most noticeable in episodes that are subject to the largest uncertainties in meteorological fields (wind directions in the Sacramento Valley and timing and strength of onshore flow in the Bay Area) within the boundary layer.
Estimation of outgoing longwave radiation from Atmospheric Infrared Sounder radiance measurements
Authors: Sun Fengying , Goldberg Mitchell D. , Liu Xingpin , Bates John J.
Published: May 2010

This study demonstrates the ability to use Atmospheric Infrared Sounder (AIRS) hyperspectral radiance measurements and collocated Clouds and the Earth's Radiant Energy System outgoing longwave fluxes to estimate top‐of‐atmosphere outgoing longwave radiation (OLR) from AIRS radiance measurements. The first 35 principal component scores of AIRS radiances from its 1707 pristine channels are used as predictors, and the regression coefficients are generated in eight regimes of AIRS view angle to account for angular dependence of the AIRS radiance observations. Tests on an independence test ensemble show that the accuracy of the AIRS OLR is near zero and the precision is less than 3 Wm−2 for all scenes and 2 Wm−2 for uniform scenes. The AIRS OLR precision for uniform scenes is much higher than the High‐Resolution Infrared Sounder OLR of 5 Wm−2 for similar comparisons with the Earth Radiation Budget Experiment OLR. The same technique of empirical regression OLR can be applied to other hyperspectral sounders such as the Cross‐track Infrared Sounder that will be on board the National Polar‐Orbiting Operational Environmental Satellite System and the Infrared Atmospheric Sounding Interferometer on the European Meteorological Polar‐orbiting satellites.
Do climate models reproduce observed solar dimming and brightening over China and Japan?
Authors: Dwyer John G. , Norris Joel R. , Ruckstuhl Christian
Published: May 2010

Previous research indicates that clear‐sky downward solar radiation measured at the surface over China significantly decreased by about −8.6 W m−2 per decade during 1961–1989 and insignificantly increased during 1990–1999. Furthermore, solar radiation over Japan remained relatively constant during 1971–1989 and significantly increased by +5.3 W m−2 per decade during 1990–1999. The present study compares observed trends with those from twentieth century simulations by 14 global climate models in the CMIP3/IPCC‐AR4. Since radiative forcing by aerosols is the primary contributor to long‐term variations in surface solar radiation, the simulations are expected to resemble the observed trends if the input aerosol histories are realistic. To minimize the confounding impact of different cloud realizations in the observations and models, the radiative effects of cloud cover anomalies are removed from the surface solar radiation anomalies via linear regression. Although all of the models exhibit significant dimming trends over China before 1990, the largest model trend is −3.4 W m−2 per decade, less than half the magnitude and significantly different from the observed trend. Models including black carbon aerosol produce stronger decreasing trends than those that do not. The models also fail to reproduce the trend during 1990–1999 over Japan, and the largest model trend is +2.3 W m−2 per decade, only about half of the observed trend. These results suggest that global climate models uniformly underestimate the increase in aerosol radiative forcing over China prior to 1990 and uniformly underestimate the decrease in aerosol radiative forcing over Japan after 1990.
Changes in lake stratification and oxygen distribution inferred from two contrasting records of magnetotactic bacteria and diatoms
Authors: Paasche Øyvind , Larsen Jorunn
Published: May 2010

Magnetotactic bacteria (MTB) and diatoms produce hard parts on seasonal timescales that continuously becomes embedded in various soft sediment archives. Consequently, they can, and are, frequently used to reconstruct past environmental conditions in oceans, fjords, and freshwater basins. In this study, we observe how these two cosmopolitan creatures can be used to track vertical shifts in the distribution of oxygen in a small mountain lake situated in western Norway. Several short and long sediment cores have been retrieved from the lake, allowing for a detailed reconstruction that spans the last 2500 years. During periods of enhanced runoff from the catchment the Oxic‐Anoxic Transition Zone (OATZ) is lowered down to the lake‐sediment interface, due to increased convection. We posit that this condition reduces the concentration of microaerophilic magnetite‐producing MTB, an interpretation partly supported by rock magnetic analyzes. Preservation of diatom frustules is, however, improved whenever this oxygen‐rich scenario prevails. Similarly, when runoff is low, and the OATZ is lifted above the lake‐sediment interface, MTB concentration seems to increase, whereas dissolution of diatoms is more common. This consistent antiphase relationship between MTB concentration and diatom preservation, occurring on a multidecadal timescale during lowest reconstructed lake‐water pH in the lake's history, suggest a coupled response to subtle changes in external environmental variables that affect catchment and lake hydrology.
Impact of stratospheric ozone recovery on tropospheric ozone and its budget
Authors: Zeng G. , Morgenstern O. , Braesicke P. , Pyle J. A.
Published: May 2010

We consider the impact of stratospheric ozone recovery between 2000 and 2100 on modeled tropospheric ozone and the tropospheric ozone budget, using a tropospheric chemistry‐climate model. Ozone calculated from a stratospheric chemistry‐climate model is used to prescribe lower stratospheric ozone in the tropospheric model. The results show that stratospheric ozone recovery leads to significant increases of tropospheric ozone throughout the extra‐tropical troposphere, in particular, a large surface ozone increase in the Southern Hemisphere during austral winter months. Stratospheric ozone recovery and climate change contribute about equally to the increase in surface ozone during this season.
Derivatization of the azole 1‐aminobenzotriazole using laccase of Pycnoporus cinnabarinus and Myceliophthora thermophila: influence of methanol on the reaction and biological evaluation of the derivatives
Authors: Hahn Veronika , Mikolasch Annett , Wende Kristian , Bartrow Hannelore , Lindequist Ulrike , Schauer Frieder
Published: May 2010

The laccases of Pycnoporus cinnabarinus and Myceliophthora thermophila are extracellular enzymes with high protein stability. They were used for the ‘one pot’ synthesis of azole derivatives from 1‐aminobenzotriazole together with the p‐dihydroxylated laccase substrates 2,5‐dihydroxybenzoic acid methyl ester and 2,5‐dihydroxybenzoic acid ethyl ester. The reactions yielded heteromolecular dimers (in yields of up to 34%). Methanol was used as the co‐solvent to determine the influence of solvent concentration on the course of reaction. The resulting products were isolated, structurally characterized and tested for their antibacterial, antifungal and cytotoxic activities. The products showed low antimicrobial activity and low cytotoxicity compared with commercial available standard compounds but these variables exceeded those of the initial reactants used for the synthesis. In addition to the synthesis of heteromolecular dimers, oligomers were formed and structurally characterized by LC/MS (liquid chromatography/MS).
Mitosis is not the only distributor of mutated cells: Non‐mitotic endopolyploid cells produce reproductive genome‐reduced cells
Authors: Walen Kirsten H.
Published: May 2010

Giant endopolyploid nuclei (>16n) can spontaneously fragment by endomitosis (nuclear internal division) into near‐diploid cells with reproductive capacity (depolyploidization), and endotetra/octopolyploidy can undergo chromosome‐visible meiotic‐like genome reductional divisions also to replicative subcells. These unconventional divisions are associated with production of aneuploidy, which led to the question in this study of whether endopolyploidy, in general, can contribute genetic variability to tumorigenic potential. For this purpose, non‐proliferative endopolyploid cells (range: 4n–32n) in near‐senescence of normal diploid cell strains were analysed for nuclear–morphogenic changes associated with the presence of diploid‐sized nuclei in the cytoplasm. A one‐by‐one nuclear‐cutoff process gave rise to reproducing genome‐reduced cells. It was concluded that these unconventional cell divisions are, indeed, suspects of originating genetic variability. Details of these irregular mitoses were compared to ‘mitotic–meiosis’ in primitive organisms, which suggested activation of an ancestral trait in the mammalian cells.
Will high-sensitive troponin immunoassays lead to more clarity or confusion in clinical practice?
Authors: Clerico Aldo , Giannoni Alberto
Published: May 2010

Although increases in cTnI (cardiac troponin I) and cTnT (cardiac troponin T) always indicate myocardial damage, the test is not able to identify the mechanisms responsible for this damage, which may not be due to ischaemia, but rather to other clinical conditions. In the present issue of Clinical Science, Filusch and co-workers have assessed cTnT using a high-sensitive assay in patients with pulmonary arterial hypertension. Their study suggests that, even in patients with extracardiac diseases, high-sensitive troponin assays could lead to better risk stratification of patients in whom conventional cTnT assays show values within the ‘normal’ range. These findings support the hypothesis that increased levels of cTnI and cTnT are an index of cardiac tissue damage, even in patients with extracardiac diseases, thus enabling appropriate diagnosis and, when necessary and available, specific treatment.
Asymmetrically driven implosions
Authors: Vaughan K. , McAlpin S. , Foster J. M. , Stevenson R. M. , Glendinning S. G. , Sorce C.
Published: May 2010

Techniques to achieve uniform near-spherical symmetry of radiation drive on a capsule in a laser-heated hohlraum have received detailed attention in the context of inertial confinement fusion. However, much less attention has been paid to the understanding of the hohlraum physics in cases where the radiation drive departs significantly from spherical symmetry. A series of experiments has been carried out to study the implosion dynamics of a capsule irradiated by a deliberately asymmetric x-ray drive. The experimental data provide a sensitive test of radiation transport in hohlraums in which drive symmetry is modulated by asymmetric laser beam timing and the use of wall materials of different albedos. Data from foam ball and thin-shell capsule experiments are presented together with modeling using consecutively linked Lagrangian and Eulerian calculational schemes. The thin-shell capsules exhibit much stronger sensitivity to early-time asymmetry than do the foam balls, and this sensitivity results in the formation of a well-defined polar jet. These data are shown to challenge computational modeling in this highly asymmetric convergent regime. All of the experiments detailed were carried out at the OMEGA laser facility [J. M. Soures, R. L. McCrory, C. P. Verdon et al., Phys. Plasmas 3, 2108 (1996)] at the Laboratory for Laser Energetics in Rochester, NY.
Numerical investigation of auroral cyclotron maser processes
Authors: Speirs D. C. , Ronald K. , McConville S. L. , Gillespie K. M. , Phelps A. D. R. , Cross A. W. , Bingham R. , Robertson C. W. , Whyte C. G. , He W. , Vorgul I. , Cairns R. A. , Kellett B. J.
Published: May 2010

When a mainly rectilinear electron beam is subject to significant magnetic compression, conservation of magnetic moment results in the formation of a horseshoe shaped velocity distribution. It has been shown that such a distribution is unstable to cyclotron emission and may be responsible for the generation of auroral kilometric radiation—an intense rf emission sourced at high altitudes in the terrestrial auroral magnetosphere. Particle-in-cell code simulations have been undertaken to investigate the dynamics of the cyclotron emission process in the absence of cavity boundaries with particular consideration of the spatial growth rate, spectral output and rf conversion efficiency. Computations reveal that a well-defined cyclotron emission process occurs albeit with a low spatial growth rate compared with waveguide bounded simulations. The rf output is near perpendicular to the electron beam with a slight backward-wave character reflected in the spectral output with a well defined peak at 2.68 GHz, just below the relativistic electron cyclotron frequency. The corresponding rf conversion efficiency of 1.1% is comparable to waveguide bounded simulations and consistent with the predictions of kinetic theory that suggest efficient, spectrally well defined emission can be obtained from an electron horseshoe distribution in the absence of radiation boundaries.
Note: Leaf undulator to realize polarization control with low on-axis heat load
Authors: Yan J. , Qiao S.
Published: May 2010

Here, a new operational mode of an electromagnetic elliptical undulator, called leaf undulator, is proposed and studied. It can provide linearly polarized radiation at an arbitrary polarization direction depending on the magnitude and polarity of the horizontal and vertical magnetic fields. The polarization direction becomes 45° when the horizontal and vertical magnetic fields are equal in strength. It is also able to switch the operational mode to purely circular or elliptical one. To lower the on-axis power density generated by undulators operating in linear mode, different designs have been presented in the past. Leaf undulator can suppress the on-axis power density by an order of magnitude compared to the so-called Knot and Figure-8 undulators, while maintaining comparable photon flux of the fundamental harmonic. Furthermore, it is possible to reach a lower fundamental energy under linear mode than by any other design using comparable magnetic field strengths.
Homotopy based solutions of the Navier–Stokes equations for a porous channel with orthogonally moving walls
Authors: Xu Hang , Lin Zhi-Liang , Liao Shi-Jun , Wu Jie-Zhi , Majdalani Joseph
Published: May 2010

This paper focuses on the theoretical treatment of the laminar, incompressible, and time-dependent flow of a viscous fluid in a porous channel with orthogonally moving walls. Assuming uniform injection or suction at the porous walls, two cases are considered for which the opposing walls undergo either uniform or nonuniform motions. For the first case, we follow Dauenhauer and Majdalani [Phys. Fluids 15, 1485 (2003)] by taking the wall expansion ratio α to be time invariant and then proceed to reduce the Navier–Stokes equations into a fourth order ordinary differential equation with four boundary conditions. Using the homotopy analysis method (HAM), an optimized analytical procedure is developed that enables us to obtain highly accurate series approximations for each of the multiple solutions associated with this problem. By exploring wide ranges of the control parameters, our procedure allows us to identify dual or triple solutions that correspond to those reported by Zaturska et al. [Fluid Dyn. Res. 4, 151 (1988)]. Specifically, two new profiles are captured that are complementary to the type I solutions explored by Dauenhauer and Majdalani. In comparison to the type I motion, the so-called types II and III profiles involve steeper flow turning streamline curvatures and internal flow recirculation. The second and more general case that we consider allows the wall expansion ratio to vary with time. Under this assumption, the Navier–Stokes equations are transformed into an exact nonlinear partial differential equation that is solved analytically using the HAM procedure. In the process, both algebraic and exponential models are considered to describe the evolution of α(t) from an initial α0 to a final state α1. In either case, we find the time-dependent solutions to decay very rapidly to the extent of recovering the steady state behavior associated with the use of a constant wall expansion ratio. We then conclude that the time-dependent variation of the wall expansion ratio plays a secondary role that may be justifiably ignored.
Numerical study on the incompressible Euler equations as a Hamiltonian system: Sectional curvature and Jacobi field
Authors: Ohkitani K.
Published: May 2010

We study some of the key quantities arising in the theory of [Arnold “Sur la geometrie differentielle des groupes de Lie de dimension infinie et ses applications a l’hydrodynamique des fluides parfaits,” Annales de l’institut Fourier 16, 319 (1966)] of the incompressible Euler equations both in two and three dimensions. The sectional curvatures for the Taylor–Green vortex and the ABC flow initial conditions are calculated exactly in three dimensions. We trace the time evolution of the Jacobi fields by direct numerical simulations and, in particular, see how the sectional curvatures get more and more negative in time. The spatial structure of the Jacobi fields is compared to the vorticity fields by visualizations. The Jacobi fields are found to grow exponentially in time for the flows with negative sectional curvatures. In two dimensions, a family of initial data proposed by Arnold (1966) is considered. The sectional curvature is observed to change its sign quickly even if it starts from a positive value. The Jacobi field is shown to be correlated with the passive scalar gradient in spatial structure. On the basis of Rouchon’s physical-space based expression for the sectional curvature (1984), the origin of negative curvature is investigated. It is found that a “potential” αξ appearing in the definition of covariant time derivative plays an important role, in that a rapid growth in its gradient makes a major contribution to the negative curvature.
Hollow tin/chromium whiskers
Authors: Cheng Jing , Vianco Paul T. , Li James C.M.
Published: May 2010

Tin whiskers have been an engineering challenge for over five decades. The mechanism has not been agreed upon thus far. This experiment aimed to identify a mechanism by applying compressive stresses to a tin film evaporated on silicon substrate with an adhesion layer of chromium in between. A phenomenon was observed in which hollow whiskers grew inside depleted areas. Using focused ion beam, the hollow whiskers were found to contain both tin and chromium. At the bottom of the depleted areas, thin tin/tin oxide film remained over the chromium layer. It indicates that tin transport occurred along the interface between tin and chromium layers.
Microstructure and ferromagnetic property in CaRuO3 thin films with pseudoheterostructure
Authors: Chen Y. B. , Zhou Jian , Wu Fei-xiang , Ji Wei-jing , Zhang Shan-Tao , Chen Yan-Feng , Zhu Yong-Yuan
Published: May 2010

CaRuO 3 thin films were synthesized on SrTiO3 substrates by pulsed laser deposition. Detailed microstructure analysis by transmission electron microscopy revealed the pseudoheterostructure in CaRuO3 films. It consists of a coherently strained cubic CaRuO3 layer contacted with substrate, as well as a strained orthorhombic CaRuO3 layer. The orthorhombic CaRuO3 layer is composed of two types of domains. The ferromagnetic property of the pseudoheterostructure CaRuO3 was revealed by superconducting quantum interference device measurement. This is due to the cubic CaRuO3 layer, which is supported by first-principle calculations. The formation mechanism of pseudoheterostructure in ultrathin CaRuO3 thin films was proposed.
Electrically pumped photonic crystal nanocavity light sources using a laterally doped p-i-n junction
Authors: Ellis Bryan , Sarmiento Tomas , Mayer Marie , Zhang Bingyang , Harris James , Haller Eugene , Vuckovic Jelena
Published: May 2010

A technique to electrically pump photonic crystal nanocavities using a lateral p-i-n junction is described. Ion implantation doping is used to form the junction, which under forward bias pumps a gallium arsenide photonic crystal nanocavity with indium arsenide quantum dots. Efficient cavity-coupled electroluminescence is demonstrated and the electrical characteristics of the diode are presented. The fabrication improvements necessary for making an electrically pumped nanocavity laser using a lateral junction are discussed.
Broad area lasers with monolithically integrated transverse mode selector
Authors: Hoffmann D. , Huthmacher K. , Döring C. , Fouckhardt H.
Published: May 2010

AlGaInAsSb-based multiple quantum well broad area lasers (BALs) with a monolithically integrated Fourier-optical 4f spatial-frequency-filter for transverse mode selection (TMS) are realized. Laser samples with filters for the selection of the fundamental transverse mode (no. 0; TMS0) and—for proof of principle-higher order modes, here exemplarily mode no. 8 (TMS8), are prepared; their emission characteristics are investigated. The concept of BAL and TMS integration within the active laser chip is verified.
High genetic diversity in a clonal relict Alexgeorgea nitens (Restionaceae): implications for ecological restoration
Authors: Sinclair Elizabeth , Krauss Siegfried , Cheetham Belinda , Hobbs Richard
Published: May 2010

The importance of genetic issues associated with the sourcing of propagules is increasingly recognised for successful ecological restoration. A consideration of life history traits has contributed to ‘best-guess’ scenarios on the appropriate location and desirable properties of local provenance source populations, but these can lack precision. For clonal species, population genetic structure and variation will depend on the balance between the extent and growth rate of asexual clones, sexual reproduction, pollen dispersal, and subsequent seed dispersal and recruitment. We assessed patterns of population genetic structure and variation for Alexgeorgea nitens (Nees) L. Johnston & B. Briggs (Restionaceae), a dioecious, clonal, perennial species, with novel life history traits. Our results show high levels of genetic diversity within populations, and surprisingly low levels of population differentiation (ΦST = 0.17). We suggest that the high genetic diversity observed within these populations reflects extensive pollen dispersal and successful seeding (sexual reproduction) and recruitment events, even though direct observations of seedling recruitment are rare. In this case, a ‘best-guess’ propagule-sourcing scenario based on life-history traits that appear to limit dispersal capability does not predict the extent of high local genetic diversity and weak population genetic structure in A. nitens.
Effect of variable soil phosphorus on phosphorus concentrations in simulated surface runoff under intensive dairy pastures
Authors: Burkitt L. L. , Dougherty W. J. , Carlson S. M. , Donaghy D. J.
Published: May 2010

Intensive dairy operations in Australia regularly apply P fertiliser to maintain productive pasture species. However, extractable soil test P (STP) concentrations in this industry commonly exceed those required to maximise pasture production, a situation which can increase the risk of P loss to surrounding waterways. The current study examined relationships between STP (Olsen P and CaCl2 P) and surface runoff P concentrations from a red silty loam (Ferrosol), commonly used for pasture production in south-eastern Australia. Soil was mixed and re-packed into soil trays and a rainfall simulator was used to generate surface runoff. A wide range of soil Olsen P concentrations (0–20 mm, 15–724 mg/kg; 0–100 mm, 9–166 mg/kg) was created by surface-applying a range of P fertiliser rates 8 months before the rainfall simulations. A comparison of the 2 STP methods suggests that Australian soils have higher labile P concentrations for given Olsen P concentrations compared with those measured internationally, suggesting a greater likelihood of P loss in runoff. Furthermore, significant curvilinear relationships between STP and dissolved reactive P (DRP <0.45 µm) in surface runoff for both Olsen P depths (0–20 mm, r2 = 0.94; 0–100 mm, r2 = 0.91; P < 0.01) were determined, as well as significant linear relationships between DRP and both CaCl2 depths (0–20 mm, r2 = 0.83; 0–100 mm, r2 = 0.92; P < 0.01). This confirmed that the concentrations of P in surface runoff increased with increasing STP, providing further evidence of an urgent need to reduce excessive STP concentrations, to reduce the risk of P loss to the environment.
Human embryonic stem cells with biological and epigenetic characteristics similar to those of mouse ESCs
Authors: Hanna Jacob , Cheng Albert W. , Saha Krishanu , Kim Jongpil , Lengner Christopher J. , Soldner Frank , Cassady John P. , Muffat Julien , Carey Bryce W. , Jaenisch Rudolf
Published: May 2010

Human and mouse embryonic stem cells (ESCs) are derived from blastocyst-stage embryos but have very different biological properties, and molecular analyses suggest that the pluripotent state of human ESCs isolated so far corresponds to that of mouse-derived epiblast stem cells (EpiSCs). Here we rewire the identity of conventional human ESCs into a more immature state that extensively shares defining features with pluripotent mouse ESCs. This was achieved by ectopic induction of Oct4, Klf4, and Klf2 factors combined with LIF and inhibitors of glycogen synthase kinase 3β (GSK3β) and mitogen-activated protein kinase (ERK1/2) pathway. Forskolin, a protein kinase A pathway agonist which can induce Klf4 and Klf2 expression, transiently substitutes for the requirement for ectopic transgene expression. In contrast to conventional human ESCs, these epigenetically converted cells have growth properties, an X-chromosome activation state (XaXa), a gene expression profile, and a signaling pathway dependence that are highly similar to those of mouse ESCs. Finally, the same growth conditions allow the derivation of human induced pluripotent stem (iPS) cells with similar properties as mouse iPS cells. The generation of validated “naïve” human ESCs will allow the molecular dissection of a previously undefined pluripotent state in humans and may open up new opportunities for patient-specific, disease-relevant research.
Rapid Communication: Interference in Short-Term Auditory Memory
Authors: Mercer Tom , McKeown Denis
Published: May 2010

Although interference is a well-established forgetting function in short-term auditory memory, an adequate understanding of its underlying mechanisms and time course has yet to be attained. The present study therefore aimed to explore these issues in memory for timbre. Listeners compared standard and comparison complex tones, having distinct timbres (four components varying in frequency), over a 4.7-s retention interval and made a same–different response. This interval either was silent or included one of 15 distractor tones occurring 0 ms, 100 ms, or 1,200 ms after the standard. These distractors varied in the extent to which the frequencies of their component tones were shared with the standard. Performance in comparing the two tones was significantly impaired by distractors composed of novel frequencies, regardless of the temporal position at which the distractor occurred. These results were fully compatible with the recent timbre memory model (McKeown & Wellsted, 2009) and suggested that interference in auditory memory operates via a feature-overwriting mechanism.
Innovative signal processing and data analysis methods on JET for control in the perspective of next-step devices
Authors: Murari A. , Vega J. , Mazon D. , Rattà G.A. , Svensson J. , Palazzo S. , Vagliasindi G. , Arena P. , Boulbe C. , Faugeras B. , Fortuna L. , Moreau D.
Published: May 2010

In the last few years, it has been realized that more sophisticated control schemes are necessary to push the boundaries of tokamak operation and the performance of reactor-like machines. In addition, JET needs to operate safely with the new metallic wall and such protection will be needed for ITER. These objectives have motivated the development, benchmark and validation of new signal processing and data analysis methods. Two new approaches for the determination of the magnetic topology in real time have been validated on an extensive database of JET discharges, including advanced tokamak scenarios. Robust methods of confinement regime identification and disruption prediction are a prerequisite for safe, general control schemes. New identifiers have been developed and their success rates exceed 99% in determining whether plasmas are in the L or H mode. A new disruption predictor is being developed and has already provided success rates higher than 90% in realistic real-time conditions. Moreover, the generalization capability of this new predictor has been confirmed by applying it to new experimental campaigns not used for the training. The success rate remains high even more than ten campaigns, or about four years, after the last one used for the training. The deployment of video cameras in real time requires the development of new image processing algorithms, which have already been implemented and validated successfully on JET for the real-time identification of hot spots with a time resolution of tens of milliseconds. A series of new feedback schemes has also been explicitly developed not much to control the plasma but to really improve the physics understanding of some phenomena. Particularly interesting are the simultaneous control of the safety factor and pressure profiles and the real-time tracking of toroidal Alfven eigenmode instabilities. These advanced feedback schemes for physics understanding often require more advanced signal processing techniques like adaptive filtering, which have already been implemented. The paper concludes by discussing the use of these real-time analysis and control developments in next-step machines such as ITER.