bluuebunny/crossref_metadata_2025 huggingface dataset:
The anisotropy of the optical properties of ternary semiconductors formed by elements of III and VI groups
Authors: Cuculescu Elmira , Evtodiev Igor , Caraman Iuliana
Published: March 2009

The GaSxSe1‐x and GaSexTe1‐x single crystals with the composition parameter x in the range of 0 ≤ x ≤ 0.3 and 0.7 ≤ x ≤ 1 respectively have been obtained. The absorption and photoluminescence (PL) measurements have been carried out for two polarizations: E ∥ C and E ⊥ C (E is the electrical field vector of light wave and C is the crystallographic axis normal to the cleaved plane). The anisotropy of optical absorption reveals itself on the low energy wing of the n =1 free exciton band. The anisotropy coefficient increases with the temperature decrease. The edge of the absorption band is determined by direct n =1 excitons for E ⊥ C polarization and by indirect transitions at low absorption coefficient for E ∥ C polarization. The photoluminescence spectra of GaS0.2Se0.8 crystals at 78 K in E ∥ C and E ⊥ C polarizations are identical to those of GaSe. The high energy photoluminescence band is determined by the radiative emission of direct bounded excitons. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characteristics of chemical bond and vacancy formation in chalcopyrite‐type CuInSe2 and related compounds
Authors: Maeda Tsuyoshi , Wada Takahiro
Published: March 2009

We studied characteristics of chemical bond and vacancy formation in chalcopyrite‐type CuInSe2 (CIS) by first principles calculations. The chalcopyrite‐type CIS has two kinds of chemical bonds, Cu‐Se and In‐Se. The Cu‐Se bond is a weak covalent bonding because electrons occupy both bonding and antibonding orbitals of Cu 3d and Se 4p and occupy only the bonding orbital (a1) of Cu 4s and Se 4p and do not occupy the antibonding orbital (a1*) of Cu 4s and Se 4p. On the other hand, the In‐Se bond has a partially covalent and partially ionic character because the In 5s orbital covalently interacts with Se 4p; the In 5p orbital is higher than Se 4p and so the electron in the In 5p orbital moves to the Se 4p orbital. The average bond order of the Cu‐Se and In‐Se bonds can be calculated to be 1/4 and 1, respectively. The bond order of Cu‐Se is smaller than that of In‐Se. The characteristics of these two chemical bonds are related to the formation of Cu and In vacancies in CIS. The formation energy of the Cu vacancy is smaller than that of the In vacancy under both Cu‐poor and In‐poor conditions. The displacement (Δl) of the surrounding Se atoms after the formation of the Cu vacancy is smaller than the Δl after the formation of the In vacancy. The interesting and unique characteristics of CIS are discussed on the basis of the characteristics of the chemical bond. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thin film deposition of complex chalcogenide gradient layers by sputtering methods
Authors: Dittrich Herbert , Stadler Andreas , Topa Dan , Schimper Hermann‐Josef , Basch Angelika
Published: March 2009

In ternary chalcogenide systems, a lateral compositional gradient in deposited layers could help to reduce the experimental efforts drastically. At present, no sputtering method for these sulfosalt gradient layers is described. A method was developed to deposit ternary (SnS)x(Bi2S3)1‐x gradient layers by sputtering methods. Therefore, binary SnS and Bi2S3 sputter targets were prepared by uniaxial hot pressing. Halved targets were bonded together to form composite SnS/Bi2S3‐targets. Layer deposition was carried out on up to 50x100 mm2 glass and glass/Mo substrates using different sputter parameters and substrate temperatures. The (SnS)x(Bi2S3)1‐x gradient layers were characterised by microprobe, X‐ray diffraction, and UV/Vis/NIR spectrometry. The composition of the layers is determined laterally and the film structure and optical properties were correlated via the substrate coordinates. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preface: Phys. Status Solidi C 6/3
Authors: Yang Deren , Kittler Martin
Published: March 2009

These proceedings contain the contributions of the 3rd Sino–German Symposium “The Silicon Age: Silicon for Microelectronics, Photonics and Photovoltaics”, which was held from 9 to 14 June 2008 in the HNA Hotel, Hangzhou, P.R. China. Nearly 30 scientists from Germany and China were invited to present their views about different aspects of silicon.

In the silicon age, microelectronics has driven the high‐speed development of economy, science and technology in the world during the last century and affects now every aspect of our life. Solar cells based on crystalline Si are expected to cover more than 10% of the worldwide energy consumption in a few decades. Furthermore, there are intensive research activities regarding Si‐based photonics, including on‐chip integration of photonics in CMOS IC technology. In addition, new areas being connected with silicon are starting to appear, such as electrical biochips, micro‐opto‐electro‐mechanics or nanotechnology and nanoelectronics. Silicon, one can reasonably argue, is the most intensively studied solid element of all materials in the world. However, there is still a need for continuation of research and development regarding numerous aspects of Si, which are the field of work of many laboratories all over the world. Examples for such ‘hot’ areas are larger Si crystals/wafers, SiGe hetrostructures for high speed devices, Si‐based light emitters, application of Si in new micro‐opto‐electro‐mechanic devices etc.

During the 3rd Sino–German symposium, the progress regarding crystalline silicon materials in different areas has been discussed. German and Chinese scientists from universities and research institutes presented their views about the various facets of silicon materials. The symposium provided a forum for a fruitful, intensive and open communication allowing the participants to build up or intensify relationships for a close cooperation in future.

We would like to thank all participants of the symposium for their contributions and the Sino–German Science Centre in Beijing for the financial support of the symposium.

October 2008
The effect of silyl and phenyl functional group end caps on the nonlinear optical properties of polyynes: A long‐range corrected density functional theory study
Authors: Song Jong‐Won , Watson Mark A. , Sekino Hideo , Hirao Kimihiko
Published: March 2009

The polarizabilities, α, second‐hyperpolarizabilities, γ, and γ scaling factors, c, of polyynes [i‐(Pr)3 Si–(CC)n–Si i‐(Pr)3, H–(CC)n–Si i‐(Pr)3, H–(CC)n‐Ph, and Ph–(CC)n–Ph: n = 1 to 8] end‐capped with triisopropylsilane (i‐(Pr)3 Si–; TIPS) and phenyl groups were calculated using HF and DFT using the recently developed LC‐BOP and LCgau‐BOP functionals. Comparison with the α and γ values of the uncapped polyynes shows that the TIPS and phenyl end caps do not increase the α and γ values by a simple additive constant, but instead seem to expand the effective conjugation length (n) of the polyyne backbone. Using a newly‐proposed power‐law function, γ = a + b(n + Δn)c, we found that a single phenyl or TIPS end cap has the effect of increasing n by approximately Δn = 1.35 or 0.83, respectively. In the case of the phenyl end caps, we confirm that this function gives a better fit to the data than the function γ = a + bnc, even with constant b and c values, determined from a fit to the uncapped polyyne γ values (γ = bnc). In the case of the TIPS end caps, the fit to γ = a + b(n + Δn)c gives a smaller Δn, but the assumption of constant b and c is less accurate. We also compared our c values to experimental data using the commonly used function γ = a + bnc. Our results are consistent with the experimental c values, in that the c values of Ph–(CC)n–Ph are higher than those of i‐(Pr)3 Si–(CC)n–Si i‐(Pr)3. Finally, using the power‐law, γ = a + b(n + Δn)c, we predict the, as yet undetermined, experimental c value of uncapped polyynes using the experimental γ values of Ph–(CC)n–Ph (Δn = 2.7), to be ∼4.88. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Comparison of geometric, electronic, and vibrational properties for all pentagon/hexagon‐bearing isomers of fullerenes C38, C40, and C42
Authors: Małolepsza Edyta , Lee Yuan‐Pern , Witek Henryk A. , Irle Stephan , Lin Chun‐Fu , Hsieh Horng‐Ming
Published: March 2009

The self‐consistent‐charge density‐functional tight‐binding (SCC‐DFTB) method is employed for computing geometric, electronic, and vibrational properties for various topological isomers of small fullerenes. We consider all pentagon/hexagon‐bearing isomers of C38, C40, and C42 as the second part of a larger effort to catalogue the CC distance distributions, valence CCC angle distributions, electronic densities of states (DOSs), vibrational densities of states (VDOSs), and infrared (IR) and Raman spectra for fullerenes C20C180 [analogous data for C20C36 were published previously in Małolepsza et al., J Phys Chem A, 2007, 111, 6649]. Common features among the fullerenes are identified and properties characteristic for each specific fullerene cage size are discussed. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Chestega: chess steganography methodology
Authors: Desoky Abdelrahman , Younis Mohamed
Published: March 2009

Steganography is the science and art of avoiding the arousal of suspicion in covert communications. This paper presentsChessSteganography (Chestega), a novel methodology that exploits popular games like chess. Chestega conceals messages in chess related covers such as training documents, game analysis, news articles, etc. Unlike contemporary approaches, Chestega does not exploit noise to embed a message nor produce a detectable noise. Instead, authenticated data can be employed in the cover which makes it resilient to comparison attacks. Chestega is also a public approach that neither relies on the secrecy of its technique, nor need to employ a stega‐key. The paper demonstrates the feasibility of employing authenticated Chess Cover that is generated by Chessmaster 8000. Chestega is further validated through steganalysis. Copyright © 2009 John Wiley & Sons, Ltd.
Facile Plasma‐Enhanced Deposition of Ultrathin Crosslinked Amino Acid Films for Conformal Biometallization
Authors: Anderson Kyle D. , Slocik Joseph M. , McConney Michael E. , Enlow Jesse O. , Jakubiak Rachel , Bunning Timothy J. , Naik Rajesh R. , Tsukruk Vladimir V.
Published: March 2009

A novel method for the facile fabrication of conformal, ultrathin, and uniform synthetic amino acid coatings on a variety of practical surfaces by plasma‐enhanced chemical vapor deposition is introduced. Tyrosine, which is utilized as an agent to reduce gold nanoparticles from solution, is sublimed into the plasma field and directly deposited on a variety of substrates to form a homogeneous, conformal, and robust polyamino acid coating in a one‐step, solvent‐free process. This approach is applicable to many practical surfaces and allows surface‐induced biometallization while avoiding multiple wet‐chemistry treatments that can damage many soft materials. Moreover, by placing a mask over the substrate during deposition, the tyrosine coating can be micropatterned. Upon its exposure to a solution of gold chloride, a network of gold nanoparticles forms on the surface, replicating the initial micropattern. This method of templated biometallization is adaptable to a variety of practical inorganic and organic substrates, such as silicon, glass, nitrocellulose, polystyrene, polydimethylsiloxane, polytetrafluoroethylene, polyethylene, and woven silk fibers. No special pretreatment is necessary, and the technique results in a rapid, conformal amino acid coating that can be utilized for further biometallization.
SOX15 and SOX7 Differentially Regulate the Myogenic Program in P19 Cells
Authors: Savage Josée , Conley Andrew J. , Blais Alexandre , Skerjanc Ilona S.
Published: March 2009

In this study, we have identified novel roles for Sox15 and Sox7 as regulators of muscle precursor cell fate in P19 cells. To examine the role of Sox15 and Sox7 during skeletal myogenesis, we isolated populations of P19 cells with either gene stably integrated into the genome, termed P19[Sox15] and P19[Sox7]. Both SOX proteins were sufficient to upregulate the expression of the muscle precursor markers Pax3/7, Meox1, and Foxc1 in aggregated cells. In contrast to the P19[Sox7] cell lines, which subsequently differentiated into skeletal muscle, myogenesis failed to progress past the precursor stage in P19[Sox15] cell lines, shown by the lack of MyoD and myosin heavy chain (MHC) expression. P19[Sox15] clones showed elevated and sustained levels of the inhibitory factors Msx1 and Id1, which may account for the lack of myogenic progression in these cells. Stable expression of a Sox15 dominant-negative protein resulted in the loss of Pax3/7 and Meox1 transcripts, as well as myogenic regulatory factor (MRF) and MHC expression. These results suggest that Sox15, or genes that are bound by Sox15, are necessary and sufficient for the acquisition of the muscle precursor cell fate. On the other hand, knockdown of endogenous Sox15 caused a decrease in Pax3 and Meox1, but not MRF expression, suggesting that other factors can compensate in the absence of Sox15. Taken together, these results show that both Sox7 and Sox15 are able to induce the early stages of myogenesis, but only Sox7 is sufficient to initiate the formation of fully differentiated skeletal myocytes.

Disclosure of potential conflicts of interest is found at the end of this article.
X‐ray tracing study of crystal spectrometers for WDXRS application
Authors: Tadić T. , Jakšić M. , Božičević I.
Published: March 2009

Construction of a high energy resolution crystal X‐ray spectrometer to be used for wavelength‐dispersive X‐ray emission spectroscopy (WDXRS) may result in different geometrical aberrations, such as systematic X‐ray line shifts and changes of the X‐ray line shape. Most of these aberrations can be reduced by careful design of a crystal spectrometer, keeping the efficiency of the spectrometer as high as possible. The availability of high‐resolution position‐sensitive detectors and small excitation beam sizes, and therefore a possible downsized Wavelength‐dispersive X‐ray (WDX) spectrometer, increase the need for reliable simulation of aberrations involved in WDXRS. Since the experimental investigation of the impact that WDX spectrometer design has on a particular aberration is rather time‐consuming, a numerical X‐ray tracing procedure, XTRACE, has been developed and applied for this purpose. Results are given in the form of virtual X‐ray energy spectra that have been affected by the most important aberrations. Copyright © 2009 John Wiley & Sons, Ltd.
De Novo Next Generation Sequencing of Plant Genomes
Authors: Rounsley Steve , Marri Pradeep Reddy , Yu Yeisoo , He Ruifeng , Sisneros Nick , Goicoechea Jose Luis , Lee So Jeong , Angelova Angelina , Kudrna Dave , Luo Meizhong , Affourtit Jason , Desany Brian , Knight James , Niazi Faheem , Egholm Michael , Wing Rod A.
Published: March 2009

The genome sequencing of all major food and bioenergy crops is of critical importance in the race to improve crop production to meet the future food and energy security needs of the world. Next generation sequencing technologies have brought about great improvements in sequencing throughput and cost, but do not yet allow for de novo sequencing of large repetitive genomes as found in most crop plants. We present a strategy that combines cutting edge next generation sequencing with “old school” genomics resources and allows rapid cost-effective sequencing of plant genomes.
What Effect Does an Exercise Program for Healthy Pregnant Women Have on the Mother, Fetus, and Child?
Authors: Kalisiak Brooke , Spitznagle Theresa
Published: March 2009

Forty‐two percent of women report exercising during pregnancy. Current American College of Obstetrics and Gynecologists (ACOG) guidelines recommend only 30 minutes of exercise per day. Developments in research have occurred since the 2002 publication of the ACOG guidelines. Evaluation of specific outcomes related to the mother, fetus, and child provide new clinical insight regarding the safety of exercise programs for healthy pregnant women. The purpose of this focused review is to critically evaluate recent studies regarding the effect of exercise during a healthy pregnancy on maternal, fetal, and child outcomes. A search of electronic bibliographic databases was undertaken. Based on this review, healthy pregnant women can benefit from exercising at a moderate intensity for a longer duration than recommended in the current ACOG guidelines that are based on studies published before or during 2002.
Paleohydrology of the upper Laurentian Great Lakes from the late glacial to early Holocene
Authors: Breckenridge Andy , Johnson Thomas C.
Published: March 2009

Between 10,500 and 9000 cal yr BP, δ18O values of benthic ostracodes within glaciolacustrine varves from Lake Superior range from − 18 to − 22‰ PDB. In contrast, coeval ostracode and bivalve records from the Lake Huron and Lake Michigan basins are characterized by extreme δ18O variations, ranging from values that reflect a source that is primarily glacial (∼ − 20‰ PDB) to much higher values characteristic of a regional meteoric source (∼ − 5‰ PDB). Re-evaluated age models for the Huron and Michigan records yield a more consistent δ18O stratigraphy. The striking feature of these records is a sharp drop in δ18O values between 9400 and 9000 cal yr BP. In the Huron basin, this low δ18O excursion was ascribed to the late Stanley lowstand, and in the Lake Michigan basin to Lake Agassiz flooding. Catastrophic flooding from Lake Agassiz is likely, but a second possibility is that the low δ18O excursion records the switching of overflow from the Lake Superior basin from an undocumented northern outlet back into the Great Lakes basin. Quantifying freshwater fluxes for this system remains difficult because the benthic ostracodes in the glaciolacustrine varves of Lake Superior and Lake Agassiz may not record the average δ18O value of surface water.
Boreal peatland margins as repository sites of long-term natural disturbances of balsam fir/spruce forests
Authors: Lavoie Martin , Filion Louise , Robert Élisabeth C.
Published: March 2009

A multidisciplinary, high-resolution paleoecological study (Lepidoptera and plant remains, macroscopic charcoal, pollen) was conducted on a 4000-yr peat monolith extracted from the margin of an ombrotrophic peatland on Anticosti Island (Gulf of St. Lawrence, eastern Canada) to reconstruct the long-term natural disturbances (insect outbreaks, forest fires) of a balsam fir/spruce forest. We hypothesized that an activity of insect defoliators (spruce budworm, hemlock looper) was the main disturbance factor of conifer forests during the Late Holocene. The earliest remains of spruce budworm and hemlock looper were found ca. 3220 and 2350 cal yr BP, respectively. Peaks of insect head capsules occurred from ca. 1640 to ca. 625 cal yr BP. Low balsam fir pollen concentrations during this period suggest a lengthy episode (∼ 1000 yr) of high insect activity, resulting in extensive fir dieback and mortality. The long-term dynamics of the pristine balsam fir/spruce forests were mainly governed by the activity of insect defoliators. The limited extent and possibly the low occurrence of forest fires in the maritime environment of Anticosti Island allowed the development of mature coniferous stands propitious for insect infestations. Insect head capsules appeared to be a useful and effective tool for establishing insect presence and activity during the Holocene.
A Sociology of Quantification
Authors: Espeland Wendy Nelson , Stevens Mitchell L.
Published: March 2009

One of the most notable political developments of the last thirty years has been increasing public and governmental demand for the quantification of social phenomena, yet sociologists generally have paid little attention to the spread of quantification or the significance of new regimes of measurement. Our article addresses this oversight by analyzing quantification – the production and communication of numbers – as a general sociological phenomenon. Drawing on scholarship across the social sciences in Europe and North America as well as humanistic inquiry, we articulate five sociological dimensions of quantification and call for an ethics of numbers.
AVOIDING LEGAL OBLIGATIONS CREATED BY HUMAN RIGHTS TREATIES
Authors: Bates Ed
Published: March 2009

This article examines the legality of the options that may be open to a State that is unwilling to accept a legal obligation created by a human rights treaty it has already ratified. It briefly addresses the subject of ‘derogation’ from human rights treaties before looking in detail at denunciation of the same. It proceeds to examine the legality of strategies such as entering a late reservation to a human rights treaty and of denouncing the treaty with the sole purpose of entering a new reservation to it.
EQUIVOCAL HELPERS—COMPLICIT STATES, MIXED MESSAGES AND INTERNATIONAL LAW
Authors: Nolte Georg , Philipp Aust Helmut
Published: March 2009

Issues of State complicity arise ever more frequently in international relations. Rules which deal with the responsibility of States for aiding or assisting in the commission of internationally wrongful acts by other States are, however, not yet fully developed. States frequently support each other's actions without necessarily considering the potential implications of the rules on complicity in international law. This leads to another problem: is support given to another State automatically to be seen as relevant practice for the development of new customary rules or the interpretation of treaties through subsequent practice? Or is it possible for complicit States to play two different roles: to assist in some conduct while not endorsing the legal claim associated with it? This contribution aims to untangle the various facets of complicit State behaviour. It will argue that in some cases, States can indeed play two different roles. States should, however, be careful in considering the long-term implications of such behaviour.
Fluid mechanics of the flow-excited Helmholtz resonator
Authors: MA RUOLONG , SLABOCH PAUL E. , MORRIS SCOTT C.
Published: March 2009

A flow-excited Helmholtz resonator was investigated experimentally and theoretically. The analysis was focused on a simplified momentum balance integrated over the region of the orifice. The resulting expressions were used to guide an experimental programme designed to obtain measurements of the resonator pressure under flow excitation, as well as the dynamics of the shear layer in the orifice using particle image velocimetry (PIV). The pressure measurements indicated a number of distinctive features as the flow speed varied. The PIV results provided a detailed representation of the shear layer vorticity field, as well as the equivalent hydrodynamic forcing of the resonator. The forcing magnitude was found to be roughly constant over a range of flow speeds. A model was proposed that provides a prediction of the resonator pressure fluctuations based on the thickness of the approach boundary layer, the free stream speed and the acoustic properties of the resonator. The model was shown to provide an accurate representation of the resonating frequency as well as the magnitude of the resonance to within a few decibels.
Streamwise evolution of longitudinal vortices in a turbulent boundary layer
Authors: LÖGDBERG OLA , FRANSSON JENS H. M. , ALFREDSSON P. HENRIK
Published: March 2009

In this experimental study both smoke visualization and three-component hot-wire measurements have been performed in order to characterize the streamwise evolution of longitudinal counter-rotating vortices in a turbulent boundary layer. The vortices were generated by means of vortex generators (VGs) in different configurations. Both single pairs and arrays in a natural setting as well as in yaw have been considered. Moreover three different vortex blade heightsh, with the spacingdand the distance to the neighbouring vortex pairDfor the array configuration, were studied keeping the samed/handD/hratios. It is shown that the vortex core paths scale withhin the streamwise direction and withDandhin the spanwise and wall-normal directions, respectively. A new peculiar ‘hooklike’ vortex core motion, seen in the cross-flow plane, has been identified in the far region, starting around 200hand 50hfor the pair and the array configuration, respectively. This behaviour is explained in the paper. Furthermore the experimental data indicate that the vortex paths asymptote to a prescribed location in the cross-flow plane, which first was stated as a hypothesis and later verified. This observation goes against previously reported numerical results based on inviscid theory. An account for the important viscous effects is taken in a pseudo-viscous vortex model which is able to capture the streamwise core evolution throughout the measurement region down to 450h. Finally, the effect of yawing is reported, and it is shown that spanwise-averaged quantities such as the shape factor and the circulation are hardly perceptible. However, the evolution of the vortex cores are different both between the pair and the array configuration and in the natural setting versus the case with yaw. From a general point of view the present paper reports on fundamental results concerning the vortex evolution in a fully developed turbulent boundary layer.
A generalized mean-field model of the natural and high-frequency actuated flow around a high-lift configuration
Authors: LUCHTENBURG DIRK M. , GÜNTHER BERT , NOACK BERND R. , KING RUDIBERT , TADMOR GILEAD
Published: March 2009

A low-dimensional Galerkin model is proposed for the flow around a high-lift configuration, describing natural vortex shedding, the high-frequency actuated flow with increased lift and transients between both states. The form of the dynamical system has been derived from a generalized mean-field consideration. Steady state and transient URANS (unsteady Reynolds-averaged Navier–Stokes) simulation data are employed to derive the expansion modes and to calibrate the system parameters. The model identifies the mean field as the mediator between the high-frequency actuation and the low-frequency natural shedding instability.
The strong influence of substrate conductivity on droplet evaporation
Authors: DUNN G. J. , WILSON S. K. , DUFFY B. R. , DAVID S. , SEFIANE K.
Published: March 2009

We report the results of physical experiments that demonstrate the strong influence of the thermal conductivity of the substrate on the evaporation of a pinned droplet. We show that this behaviour can be captured by a mathematical model including the variation of the saturation concentration with temperature, and hence coupling the problems for the vapour concentration in the atmosphere and the temperature in the liquid and the substrate. Furthermore, we show that including twoad hocimprovements to the model, namely a Newton's law of cooling on the unwetted surface of the substrate and the buoyancy of water vapour in the atmosphere, give excellent quantitative agreement for all of the combinations of liquid and substrate considered.
Transport of inertial particles by Lagrangian coherent structures: application to predator–prey interaction in jellyfish feeding
Authors: PENG J. , DABIRI J. O.
Published: March 2009

We use a dynamical systems approach to identify coherent structures from often chaotic motions of inertial particles in open flows. We show that particle Lagrangian coherent structures (pLCS) act as boundaries between regions in which particles have different kinematics. They provide direct geometric information about the motion of ensembles of inertial particles, which is helpful to understand their transport. As an application, we apply the methodology to a planktonic predator–prey system in which moon jellyfish Aurelia aurita uses its body motion to generate a flow that transports small plankton such as copepods to its vicinity for feeding. With the flow field generated by the jellyfish measured experimentally and the dynamics of plankton described by a modified Maxey–Riley equation, we use the pLCS to identify a capture region in which prey can be captured by the jellyfish. The properties of the pLCS and the capture region enable analysis of the effect of several physiological and mechanical parameters on the predator–prey interaction, such as prey size, escape force, predator perception, etc. The methods developed here are equally applicable to multiphase and granular flows, and can be generalized to any other particle equation of motion, e.g. equations governing the motion of reacting particles or charged particles.
On the mixing of a confined stratified fluid by a turbulent buoyant plume
Authors: MOTT RICHARD W. , WOODS ANDREW W.
Published: March 2009

We investigate the mixing of a stratified fluid of finite volume by a turbulent buoyant plume. We develop a model to describe the mixing and apply this to both the cases of a two-layer stratification and a continuous stratification. With a two-layer stratification, the plume intrudes at the interface where it supplies an intermediate layer of fluid. This new layer gradually deepens, primarily mixing the original near-source layer of fluid through entrainment. Eventually, this intermediate layer becomes sufficiently buoyant that the plume penetrates into the more distal layer, leaving a partially mixed region between the original layers of fluid. Analysis of new experiments shows that the growth of the intermediate layer depends primarily on the ratio λ of (i) the filling box time, during which the plume entrains a volume of fluid equal to that in the near-source layer, and (ii) the time for the buoyancy of the near-source layer to increase to that of the more distal layer. For small values of λ, the near-source layer becomes approximately well mixed, and the penetration time of the plume scales with the buoyancy evolution time of the near-source layer. In the limit λ ~ O(1), however, the plume penetrates through into the distal layer long before the near-source layer becomes well mixed; instead, at the time of penetration, the plume leaves an intermediate partially mixed zone between the two original layers. We develop a new phenomenological model to account for the mixing in this intermediate layer based on the effective turbulent diffusion associated with the kinetic energy in the plume and compare this with the model for penetrative entrainment proposed by Kumagai (J. Fluid Mech., vol. 147, 1984, p. 105). In comparison with the experimental data, the models provide a reasonably accurate prediction of the plume penetration time, while the diffusive mixing model provides a somewhat more accurate description of the evolution of the density profile for a range 0 < λ < 1. The diffusive mixing model also leads to predictions which are consistent with some new experimental data for the case in which a plume mixes a continuously stratified layer. In particular, the model is able to predict the initial transient mixing of the region between the source and the height at which the plume intrudes laterally in the ambient fluid, thereby providing an advance on the late-time mixing model of Cardoso and Woods (J. Fluid Mech., vol. 250, 1993, p. 277). We consider the implications of these results on the turbulent penetrative entrainment associated with buoyant plumes.
On the normal incidence of linear waves over a plane incline partially covered by a rigid lid
Authors: EHRENMARK ULF T.
Published: March 2009

The effect is examined on infinitesimal standing waves over a plane beach when restricted by the arbitrary placing of a finite rigid (or permeable) lid of length ℓ on the undisturbed surface. A uniformly bounded solution for the potential function is obtained by a Green's function method. The Green's function is derived and manipulated, for subsequent computational expedience, from a previously known solution for the problem of an oscillating line source placed at an arbitrary location in the sector. Applications are made to both the case of plate anchored at the origin and the case of plate anchored some distance at sea (drifted plate problem). In both cases water column potentials and equipotentials are constructed from the numerical solution of a Fredholm equation of the second kind by finite difference discretization. Solutions are further extended to include the logarithmically singular standing wave, combination with which allows the construction of progressing waves. Computation of initially incoming progressing wave envelopes demonstrates the emergence of a partially standing wave pattern shoreward of the plate. There is no difficulty, in principle, to extend the theory to any number of plates, and this is verified by computation for the case of two plates. A new shoreline radiation condition is constructed to allow formulation, in the usual way, of the reflection/transmission problem for the plate, and results are in good qualitative agreement with a similar model on a horizontal plane bed. It is argued that the Green's function constructed here could be used in a number of diverse problems, of this linear nature, where all, or part, of the submerged boundary is that of a plane incline.
Modified Sonine approximation for granular binary mixtures
Authors: GARZÓ VICENTE , REYES FRANCISCO VEGA , MONTANERO JOSÉ MARÍA
Published: March 2009

We evaluate in this work the hydrodynamic transport coefficients of a granular binary mixture inddimensions. In order to eliminate the observed disagreement (for strong dissipation) between computer simulations and previously calculated theoretical transport coefficients for a monocomponent gas, we obtain explicit expressions of the seven Navier–Stokes transport coefficients by the use of a new Sonine approach in the Chapman–Enskog (CE) theory. This new approach consists of replacing, where appropriate in the CE procedure, the Maxwell–Boltzmann distribution weight function (used in the standard first Sonine approximation) by the homogeneous cooling state distribution for each species. The rationale for doing this lies in the well-known fact that the non-Maxwellian contributions to the distribution function of the granular mixture are more important in the range of strong dissipation we are interested in. The form of the transport coefficients is quite common in both standard and modified Sonine approximations, the distinction appearing in the explicit form of the different collision frequencies associated with the transport coefficients. Additionally, we numerically solve by the direct simulation Monte Carlo method the inelastic Boltzmann equation to get the diffusion and the shear viscosity coefficients for two and three dimensions. As in the case of a monocomponent gas, the modified Sonine approximation improves the estimates of the standard one, showing again the reliability of this method at strong values of dissipation.
Two novel phospholipid hydroperoxide glutathione peroxidase genes ofParagonimus westermaniinduced by oxidative stress
Authors: KIM S.-H. , CAI G.-B. , BAE Y.-A. , LEE E.-G. , LEE Y.-S. , KONG Y.
Published: March 2009

Phospholipid hydroperoxide glutathione peroxidase (PHGPx; GPx4) plays unique roles in the protection of cells against oxidative stress by catalysing reduction of lipid hydroperoxides. We characterized 2 novelGPxgenes from a lung fluke,Paragonimus westermani(designatedPwGPx1andPwGPx2). These single copy genes spanned 6559 and 12 371 bp, respectively, and contained each of 5 intervening introns. ThePwGPx2harboured a codon for Sec and a Sec insertion sequence motif. Proteins encoded by theParagonimusgenes demonstrated a primary structure characteristic to the PHGPx family, including preservation of catalytic and glutathione-binding domains and absence of the subunit interaction domain. Expression ofPwGPx1increased gradually as the parasite matured, whereas that ofPwGPx2was temporally regulated.PwGPx2was expressed at the basal level from the metacercariae to the 3-week-old juveniles; however, the expression was significantly induced in the 7-week-old immature worms and reached a plateau in the 12-week-old adults and eggs. PwGPx1 and PwGPx2 were largely localized in vitellocytes within vitelline glands and eggs. Oxidative stress-inducible paraquat, juglone and H2O2substantially augmented thePwGPx1andPwGPx2expressions in viable worms by 1·5- to 11-fold. Our results strongly suggested that PwGPxs may actively participate in detoxification of oxidative hazards inP. westermani.
Forty years of helminth biochemistry
Authors: BARRETT J.
Published: March 2009

This review describes some of the developments in helminth biochemistry that have taken place over the last 40 years. Since the early 1970s the main anabolic and catabolic pathways in parasitic helminths have been worked out. The mode of action of the majority of anthelmintics is now known, but in many cases the mechanisms of resistance remain elusive. Developments in helminth biochemistry have depended heavily on developments in other areas. High throughput methods such as proteomics, transcriptomics and genome sequencing are now generating vast amounts of new data. The challenge for the future is to interpret and understand the biological relevance of this new information.
The saga of schistosome migration and attrition
Authors: WILSON R. A.
Published: March 2009

Schistosomes infect the mammalian host by direct penetration of the skin and must then undergo a protracted migration to the site of parasitization, forSchistosoma mansonithe hepatic portal vasculature. This article reviews the work published roughly between 1976 and 1986 that clarified our understanding of the process in the laboratory mouse. A combination of histopathology, larval injection experiments and autoradiographic tracking revealed that migration involved one to several circuits of the pulmonary-systemic vasculature before chance delivery in cardiac output to splanchnic arteries that lead indirectly to the portal tract. The kinetics of migration through different capillary beds was established, with the lungs of naïve mice not the skin proving the greatest obstacle; a proportion of schistosomula entered the alveoli from where they did not recover. The ‘immunity’ displayed by mice with a chronic infection was shown to be an artefact of a ‘leaky’ hepatic portal system, generated as a result of egg-induced hepatic pathology. The blockade of pulmonary migration was exacerbated in mice vaccinated with irradiated cercariae by immune-mediated inflammatory foci that developed around lung schistosomula thus decreasing the proportion that matured, but parasite elimination was a prolonged process, not an acute cytolytic ‘hit.’
Transcriptome analysis ofSchistosoma mansonilarval development using serial analysis of gene expression (SAGE)
Authors: TAFT A. S. , VERMEIRE J. J. , BERNIER J. , BIRKELAND S. R. , CIPRIANO M. J. , PAPA A. R. , McARTHUR A. G. , YOSHINO T. P.
Published: March 2009

Infection of the snail,Biomphalaria glabrata, by the free-swimming miracidial stage of the human blood fluke,Schistosoma mansoni, and its subsequent development to the parasitic sporocyst stage is critical to establishment of viable infections and continued human transmission. We performed a genome-wide expression analysis of theS. mansonimiracidia and developing sporocyst using Long Serial Analysis of Gene Expression (LongSAGE). Five cDNA libraries were constructed from miracidia andin vitrocultured 6- and 20-day-old sporocysts maintained in sporocyst medium (SM) or in SM conditioned by previous cultivation with cells of theB. glabrataembryonic (Bge) cell line. We generated 21 440 SAGE tags and mapped 13 381 to theS. mansonigene predictions (v4.0e) either by estimating theoretical 3′ UTR lengths or using existing 3′ EST sequence data. Overall, 432 transcripts were found to be differentially expressed amongst all 5 libraries. In total, 172 tags were differentially expressed between miracidia and 6-day conditioned sporocysts and 152 were differentially expressed between miracidia and 6-day unconditioned sporocysts. In addition, 53 and 45 tags, respectively, were differentially expressed in 6-day and 20-day cultured sporocysts, due to the effects of exposure to Bge cell-conditioned medium.
Under what conditions can oil and gas developments in the Arctic be acceptable, and to whom?
Authors: Palmer Andrew C.
Published: March 2009

It is sometimes argued that the Arctic is so fragile that oil and gas development is never acceptable. Occasionally the argument rests on a fundamental objection to any development of fossil fuel resources. This paper will argue that under some conditions development can be carried out in a way that safeguards the natural environment, and that when the resources are exhausted all traces can be removed. This conclusion applies both offshore and onshore. It will require great sensitivity and care, and the application of the best technology developed by the petroleum industry for developments elsewhere. Some locations will have to be left inviolate until better technology is discovered, and perhaps for ever. The argument will be illustrated by case studies, some of them taken from completed projects.
The origins of Canada's first Eastern Arctic Patrol, 1919–1922
Authors: Cavell Janice , Noakes Jeff
Published: March 2009

It is widely believed among historians that in 1920, the Danish explorer Knud Rasmussen and the Danish government challenged Canada's sovereignty over Ellesmere Island. This paper draws on a wide range of Canadian and British government files and private papers to contest this view. It demonstrates that Prime Minister Arthur Meighen and others in Ottawa were initially convinced by Vilhjalmur Stefansson that Denmark harboured territorial ambitions in the north, but most realised in the spring of 1921 that they had been mistaken. However, one civil servant, J. B. Harkin, stubbornly maintained his belief in the Danish threat. After Mackenzie King's Liberals came to power, Harkin was able to obtain a hearing for his views. It was largely due to Harkin's persistence that the first Eastern Arctic Patrol went north in 1922.
‘Will the Russians abandon Mirny to the penguins after 1959 . . . or will they stay?’
Authors: Gan Irina
Published: March 2009

This paper traces the Soviet responses to initiatives of international scientific institutions for collaborative research in the Antarctic dating from the International Geophysical Year (IGY) through to the formation of the Special Committee for Antarctic Research (SCAR) and the extension of the IGY for a year during the International Geophysical Cooperation. It demonstrates the consistently positive attitudes of the USSR to these initiatives and the steps that were taken at the national level to enable it to continue international collaboration. Other countries with interests in the Antarctic conjectured whether the Soviets had a long term strategy for continuing their presence in the South Polar region. The evidence suggests that from the day the Soviets set foot on the Antarctic continent, they had no intention of leaving.
Amchitka Island, Alaska: moving towards long term stewardship
Authors: Benning Jennifer L. , Barnes David L. , Burger Joanna , Kelley John J.
Published: March 2009

Amchitka Island, Alaska, is a historical underground nuclear test site. Three underground tests were conducted there by the United States Atomic Energy Commission, now US Department of Energy (USDOE), between 1965 and 1971. These were Long Shot, an 80 kiloton detonation; Milrow, a 1 megaton detonation; and Cannikin, a 5 megaton detonation. Subsequent to these tests, several scientific assessments have been conducted regarding the impacts of the tests on the terrestrial and marine environments surrounding the island. However, many citizens and groups still voice concerns over the potential for detrimental effects on human and ecological health. In its responsibility for the long term protection of human and ecological health consequent to its nuclear programme, USDOE has recently prepared a plan for the long term surveillance and monitoring of the site. The purpose of this paper is to summarise the history of the island, specifically with regards to its use as a nuclear test site, to summarise the results of investigative activities following testing, to summarise USDOE's plan for surveillance and monitoring, and to offer the authors' viewpoints on the long term stewardship of the island. The authors deemed the stewardship plan to be essentially protective of human and ecological health; however, they recommend a stronger commitment to site oversight and review, as well as to future research, for addressing uncertainties remaining at the island.
Una Peaks: a long overdue Antarctic geographical naming
Authors: Splettstoesser John
Published: March 2009

A new name for a geographical feature in the Antarctic Peninsula known for many years by its colloquial name of Una's Tits, was formally approved by the Antarctic place names committee of the United Kingdom. It is now known as Una Peaks, named for a former secretary in the governor's office, Stanley, Falkland Islands.
Whither the Arctic 2009? Further developments
Authors: Young Oran R.
Published: March 2009

This note updates the author's paper with the title ‘Whither the Arctic? Conflict or cooperation in the circumpolar north’. published in the last issue of this journal (Young 2009). Particular attention is paid to the policy issues arising from the ongoing and rapid changes unfolding in the Arctic.
The Logic of Local Business Associations: an Analysis of Voluntary Chambers of Commerce
Authors: Bennett Robert J.
Published: March 2009

This paper seeks to assess how far local business organisations, such as Chambers of Commerce, are maintained chiefly by the factors hypothesised by Mancur Olson as the forces being behind collective action: the costs and benefits of business services. The paper reviews the theoretical arguments to support this hypothesis and then assesses the case of UK Chambers of Commerce using empirical evidence from surveys of businesses and Chambers. The UK Chambers are a purely private law voluntary structure, unlike many European counterparts. The analysis demonstrates that in such a system the overwhelming motive for business membership is to access services withspecificrather than collective benefits. In turn Chamber managers tend to respond by financing services chiefly through service fees rather than flat rate subscriptions. In an Olsonian world with purely voluntary Chambers, few businesses will pay forgeneralcollective goods (such as lobbying, representation or support to government) that others can consume at no cost. The paper also demonstrates strong differences between types of Chambers: large Chambers being largely service and fee oriented, small Chambers being more often collective action bodies. Overall, however, local Chambers have features common to other business organisations of being variable in size and resources, most are small, and the structure is fragmented. Conclusions are drawn from these findings for government policy.
Asymptotically stable biped gait generation based on stability principle of rimless wheel
Authors: Asano Fumihiko , Luo Zhi-Wei
Published: March 2009

We investigated and identified the conditions necessary for stable dynamic gait generation in biped robots from the mechanical energy balance point of view. The equilibrium point at impact in a dynamic gait is uniquely determined by two conditions; keeping the restored mechanical energy constant and settling the relative hip-joint angle to the desired value before impact. The generated gait then becomes asymptotically stable around the equilibrium point determined by these conditions. This is shown by a simple recurrence formula of the kinetic energy immediately before impact. We verified this stability theorem using numerical simulation of virtual passive dynamic walking. The results were compared with those for a rimless wheel and an inherent stability principle was derived. Finally, we derived a robust control law using a reference mechanical energy trajectory and demonstrated its effectiveness numerically.