bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of the liquid-vapor spinodal from interfacial properties obtained from molecular dynamics and lattice Boltzmann simulations
Authors: Imre A. R. , Mayer G. , Házi G. , Rozas R. , Kraska T.
Published: March 2008

Interfacial pressure and density profiles are calculated from molecular dynamics and lattice Boltzmann simulations of a liquid film in equilibrium with its vapor. The set of local values of tangential pressure and density along an interface exhibits a van der Waals-type loop; starting from the stable vapor bulk phase one passes through metastable and unstable states to the stable liquid bulk phase. The minimum and maximum values of the profile of tangential pressure are related to the liquid and vapor spinodal states, respectively. The spinodal pressures turn out to be linearly related to the extreme values of the tangential pressure in the interface. The comparison with equations of state shows good agreement with the simulation results of the spinodals. In addition the properties of the metastable region are obtained. Based on this investigation a method is proposed for the estimation of the liquid spinodal from experimentally obtained interfacial properties. Estimations for water and helium are presented.
Magnetic anisotropy and crystalline orientation in high Hk FeCoB thin films
Authors: Hashimoto Atsuto , Matsuu Toshimitsu , Tada Masaru , Nakagawa Shigeki
Published: March 2008

FeCoB thin films with a high magnetic anisotropy field Hk were studied. Crystal structure of the FeCo was investigated by using x-Ray diffraction with particular interest for understanding the scheme to produce a high Hk in the FeCoB films. The as-deposited film with a high Hk of 280Oe showed a well-crystallized bcc (110) texture of FeCo and an asymmetric profile in the rocking curve measured along the easy axis. The pole figure profile revealed that the maximum diffraction intensity was observed at the point other than the original point, namely, the tilted crystal orientation to the substrate plane. In addition, elliptical contour lines of diffraction intensity were observed and their major axis aligned with the direction of the peak shift. These results indicated the correlation among the crystal orientation and the easy axis direction and also the incident direction of the sputtering particles to the substrate.
Performance comparison of various magnetic circuits of integrated microspeakers and dynamic receivers used for mobile phones
Authors: Kim Kwang-Seok , Kwon Joong-Hak , Hwang Sang-Moon , Hwang Gun-Yong
Published: March 2008

An integrated device (a microspeaker and dynamic receiver within one structure) has been developed to actualize efficient size reduction. In this article, three magnetic circuit structures of an integrated device are introduced and their characteristics are compared. A systematic analysis of a magnetic field is performed using finite element method analysis. In conclusion, type 1 has the highest electromagnetic force and the best acoustical characteristics.
Thermodynamics of adiabatic cross polarization
Authors: Lee Jae-Seung , Khitrin A. K.
Published: March 2008

Using a spin-temperature approach, we describe a scheme of adiabatic cross polarization, based on demagnetization/remagnetization, when the Zeeman order of abundant nuclei in the laboratory frame is first adiabatically converted into the dipolar order, and then, into the Zeeman order of rare nuclei. The scheme, implemented with two low-power frequency-sweeping pulses, is very efficient for static samples and can significantly increase polarization of rare nuclei, compared to the conventional Hartmann–Hahn cross polarization. The experimental examples are presented for a solid, liquid crystal, and small molecules in a liquid-crystalline solvent.
Quantum Monte Carlo calculations of the potential energy curve of the helium dimer
Authors: Springall R. , Per M. C. , Russo S. P. , Snook I. K.
Published: March 2008

We report results of two quantum Monte Carlo methods—variational Monte Carlo and diffusion Monte Carlo—on the potential energy curve of the helium dimer. In contrast to previous quantum Monte Carlo calculations on this system, we have employed trial wave functions of the Slater-Jastrow form and used the fixed node approximation for the fermion nodal surface. We find both methods to be in excellent agreement with the best theoretical results at short range. In addition, the diffusion Monte Carlo results give very good agreement across the whole potential energy curve, while the Slater-Jastrow wave function fails to bind the dimer at all.
Fermionic quasifree states and maps in information theory
Authors: Dierckx B. , Fannes M. , Pogorzelska M.
Published: March 2008

This paper and the results therein are geared toward building a basic toolbox for calculations in quantum information theory of quasifree fermionic systems. Various entropy and relative entropy measures are discussed. The main emphasis is on completely positive quasifree maps. The set of quasifree affine maps on the state space is determined and fully characterized in terms of operations on one-particle subspaces. For a subclass of trace-preserving completely positive maps and for their duals, Choi matrices and Jamiolkowski states are discussed.
Calculation of free-energy differences and potentials of mean force by a multi-energy gap method
Authors: Zhou Huan-Xiang
Published: March 2008

A method is proposed to significantly accelerate the convergence of free-energy calculations. It introduces a bias factor in Monte Carlo simulations or, equivalently, a bias force in molecular dynamics simulations. The bias factor targets the energy gap, i.e., the difference in energy function between two states, and is therefore specifically designed for calculating free-energy differences. The goal is to make the probability density of the energy gap as uniform as possible, thus allowing for its accurate determination. An iterative procedure, based on simulations at higher temperatures, is devised to obtain the bias factor. The same method naturally extends to the calculation of potentials of mean force. The generalized coordinate, for which the potential of mean force is to be calculated, now plays the role of the energy gap. Applications to model systems confirm the expected increase in accuracy of calculated free-energy differences and potentials of mean force.
A parameter study of separation modes of adhering microcontacts
Authors: Du Yan , Adams George G. , McGruer Nicol E. , Etsion Izhak
Published: March 2008

A finite element model was developed to study adhesion of elastic-plastic microcontacts in a previous investigation. An interesting result was the identification of two distinct separation modes, i.e. brittle and ductile separation. In the current study, that model is used to conduct a series of simulations to determine the influence of four nondimensional parameters (including the maximum load parameter) on the contact and on the separation modes. The results show that the parameter S (the ratio of the theoretical stress to the hardness) and δf∕δc (representing the loading level) are the most important. Smaller S can only lead to brittle separation, while larger S can cause either separation mode depending on δf∕δc. Ductile separation is more likely to occur at smaller δf∕δc and brittle separation at greater δf∕δc. The transition between the two separation modes occurs at about S=1.2 (for δf∕δc=30) which corresponds to the theoretical stress for adhesion being 20% greater than the hardness. This result is qualitatively similar to the existing simplified analytical models, in that the adhesion energy, the hardness, and the loading level play important roles in the occurrence of ductile separation. However, there are important quantitative differences. Comparisons are also made with molecular dynamics simulations of a contact and with a fracture mechanics model of crack propagation.
Optical properties of tungsten oxide thin films with protons intercalated during sputtering
Authors: Yamada Y. , Tajima K. , Bao S. , Okada M. , Yoshimura K. , Roos A.
Published: March 2008

Tungsten oxide thin films with protons intercalated during deposition (HxWO3) were prepared using reactive direct-current-magnetron sputtering in a gas mixture of argon, oxygen, and hydrogen. The as-deposited films fabricated under suitable conditions were colored due to the formation of tungsten bronze. The concentration of intercalated protons, given by the x values in HxWO3, was evaluated by ejecting protons electrochemically from the films. The x value of the films prepared at a constant working pressure was found to be proportional to the hydrogen flow ratio during deposition. On the other hand, the x value of the films prepared at a constant hydrogen flow ratio decreased sharply with increasing working pressure during deposition. The dispersion of the extinction coefficient (κ) of the films was estimated by analyzing the experimental spectra of Ψ and Δ measured with spectroscopic ellipsometry using the model composed of a homogeneous tungsten bronze layer with an additional surface roughness layer. As a result of this analysis, the κ value was found to increase sharply with the number of intercalated protons. There was a linear dependence between the κ value and the x value for x<0.2, while for x>0.3, the absorption saturated. This indicates that it is possible to evaluate the x value of HxWO3 films using spectroscopic ellipsometry.
High-pressure effects on the optical-absorption edge of CdIn2S4, MgIn2S4, and MnIn2S4 thiospinels
Authors: Ruiz-Fuertes J. , Errandonea D. , Manjón F. J. , Martínez-García D. , Segura A. , Ursaki V. V. , Tiginyanu I. M.
Published: March 2008

The effect of pressure on the optical-absorption edge of CdIn2S4, MgIn2S4, and MnIn2S4 thiospinels at room temperature is investigated up to 20GPa. The pressure dependence of their band gaps has been analyzed using Urbach’s rule. We have found that, within the pressure range of stability of the low-pressure spinel phase, the band gaps of CdIn2S4 and MgIn2S4 exhibit a linear blueshift with pressure, whereas the band gap of MnIn2S4 exhibits a pronounced nonlinear shift. In addition, an abrupt decrease of the band-gap energies occurs in the three compounds at pressures of 10, 8.5, and 7.2GPa, respectively. Beyond these pressures, the optical-absorption edge redshifts upon compression for the three studied thiospinels. All these results are discussed in terms of the electronic structure of each compound and their reported structural changes.
Spontaneous polarization model for surface orientation dependence of diamond hole accumulation layer and its transistor performance
Authors: Hirama K. , Takayanagi H. , Yamauchi S. , Yang J. H. , Kawarada H. , Umezawa H.
Published: March 2008

Diamond metal-oxide-semiconductor field-effect transistors (FETs) have been fabricated on IIa-type large-grain diamond substrates with a (110) preferential surface. The drain current and cutoff frequency are −790mA∕mm and 45GHz, respectively, which are higher than those of single-crystal diamond FETs fabricated on (001) homoepitaxial diamond films. The hole carrier density of the hole accumulation layer depends on the orientation of the hydrogen-terminated diamond surface, for which (110) preferentially oriented films show 50%–70% lower sheet resistance than a (001) substrate. We propose that the hole density of the surface accumulation layer is proportional to the C–H bond density on the surface.
Fibrous flexible solid-type dye-sensitized solar cells without transparent conducting oxide
Authors: Fan Xing , Chu Zengze , Chen Lin , Zhang Chao , Wang Fuzhi , Tang Yanwei , Sun Jianliang , Zou Dechun
Published: March 2008

We have explored a type of all-solid fibrous flexible dye-sensitized solar cells without transparent conducting oxide based on a CuI electrolyte. The working electrode’s substrate is a metal wire. Cu wire counterelectrode is twisted with the dye-sensitized and CuI-coated working electrode. The cell’s apparent diameter is about 150μm. The cell’s current-voltage output depends little on the incident angle of light. A 4-cm-long fibrous cell’s open-circuit voltage and short-circuit current generate 304mV and 0.032mA, respectively. The interfacial interaction between the two electrodes has a significant influence on the inner charge transfer of the cell.
Molecular simulation of protein dynamics in nanopores. I. Stability and folding
Authors: Javidpour Leili , Tabar M. Reza Rahimi , Sahimi Muhammad
Published: March 2008

Discontinuous molecular dynamics simulations, together with the protein intermediate resolution model, an intermediate-resolution model of proteins, are used to carry out several microsecond-long simulations and study folding transition and stability of α-de novo–designed proteins in slit nanopores. Both attractive and repulsive interaction potentials between the proteins and the pore walls are considered. Near the folding temperature Tf and in the presence of the attractive potential, the proteins undergo a repeating sequence of folding/partially folding/unfolding transitions, with Tf decreasing with decreasing pore sizes. The unfolded states may even be completely adsorbed on the pore’s walls with a negative potential energy. In such pores the energetic effects dominate the entropic effects. As a result, the unfolded state is stabilized, with a folding temperature Tf which is lower than its value in the bulk and that, compared with the bulk, the folding rate decreases. The opposite is true in the presence of a repulsive interaction potential between the proteins and the walls. Moreover, for short proteins in very tight pores with attractive walls, there exists an unfolded state with only one α-helical hydrogen bond and an energy nearly equal to that of the folded state. The proteins have, however, high entropies, implying that they cannot fold onto their native structure, whereas in the presence of repulsive walls the proteins do attain their native structure. There is a pronounced asymmetry between the two termini of the protein with respect to their interaction with the pore walls. The effect of a variety of factors, including the pore size and the proteins’ length, as well as the temperature, is studied in detail.
Excited states of the A free exciton in CuInS2
Authors: Yakushev M. V. , Martin R. W. , Mudryi A. V. , Ivaniukovich A. V.
Published: March 2008

High quality CuInS2 single crystals, grown by the traveling heater method in an indium solvent, were studied using reflectance and photoluminescence at 4.2K. The first, EA(n=2)=1.5494eV, and second, EA(n=3)=1.5532eV, excited states of the A free exciton have been observed in the photoluminescence spectra. Accurate values of the A exciton binding energy EFEA=18.5meV and Bohr radius aBA=3.8nm, bandgap Eg=1.5540eV at 4.2K and static dielectric constant ε=10.2 have been derived assuming a hydrogenic model.
Anomalous pressure evolution of the axial ratio c∕a in hcp cobalt: Interplay between structure, magnetism, and lattice dynamics
Authors: Antonangeli Daniele , Benedetti Laura Robin , Farber Daniel L. , Steinle–Neumann Gerd , Auzende Anne-line , Badro James , Hanfland Michael , Krisch Michael
Published: March 2008

We performed angle-dispersive x-ray diffraction measurements on hydrostatically compressed hcp cobalt to 90GPa. Near 75GPa, we document an inversion in the pressure derivative of the axial ratio c∕a with no discontinuity in the volume and lattice parameters compression curves. These results are also reproduced by ab initio calculations. Our study indicates significant interactions among structure, magnetism and elasticity, suggesting that the collapse of the magnetic moment is responsible for the observed anomaly in c∕a, as well as for the anomalies in the elastic and vibrational properties of hcp Co at high pressure.
Unshielded fetal magnetocardiography system using two-dimensional gradiometers
Authors: Seki Yusuke , Kandori Akihiko , Kumagai Yukio , Ohnuma Mitsuru , Ishiyama Akihiko , Ishii Tetsuko , Nakamura Yoshiyuki , Horigome Hitoshi , Chiba Toshio
Published: March 2008

We developed a fetal magnetocardiography (fMCG) system that uses a pair of two-dimensional gradiometers to achieve high signal-to-noise ratio. The gradiometer, which is based on a low-Tc superconducting quantum interference device, detects the gradient of a magnetic field in two orthogonal directions. Gradiometer position is easy to adjust by operating the gantry to drive the cryostat in both the swinging and axial directions. As a result, a fMCG waveform for 25weeks’ gestation was measured under an unshielded environment in real time. Moreover, the P and T waves for 25 and 34weeks’ gestation, respectively, were obtained by averaging. These results indicate that this two-dimensional gradiometer is one of the most promising techniques for measuring fetal heart rate and diagnosing fetal arrhythmia.
Efficient optical coupling into metal-insulator-metal plasmon modes with subwavelength diffraction gratings
Authors: Preiner Michael J. , Shimizu Ken T. , White Justin S. , Melosh Nicholas A.
Published: March 2008

We demonstrate efficient optical coupling into metal-insulator-metal (MIM) plasmon modes. Subwavelength grating couplers are used to optically excite the MIM plasmon mode, which is observed with reflection spectroscopy. Coupling efficiencies of up to 28% are measured for insulator thicknesses of 12nm. It is found that the MIM resonance has a significant shift in energy as a function of grating depth. This shift is much larger than that seen from traditional surface plasmon modes. MIM plasmons are promising tools for probing molecular junctions due to strong field confinement and high field intensities within the insulator.
Unipolar resistive switching in CoFeB∕MgO∕CoFeB magnetic tunnel junction
Authors: Yoshida Chikako , Kurasawa Masaki , Lee Young Min , Aoki Masaki , Sugiyama Yoshihiro
Published: March 2008

We found that a magnetic tunnel junction (MTJ) shows two types of memory operation. One is spin torque switching, and the other is electric stress induced resistive switching (RS), which is observed in various metal oxides. A MTJ in RS operation exhibits a resistance ratio of greater than 100, an endurance of more than 400cycles, and data retention in excess of 89h at 85°C, which is suitable for programable switch elements. The MTJ can operate as a programable switch, as well as a storage element, in a field programable gate array.
Bias-selectable tricolor tunneling quantum dot infrared photodetector for atmospheric windows
Authors: Ariyawansa G. , Apalkov V. , Perera A. G. U. , Matsik S. G. , Huang G. , Bhattacharya P.
Published: March 2008

A tricolor infrared detector with bias-selectable peaks based on tunneling quantum dot infrared photodetector (T-QDIP) architecture is demonstrated. Photoabsorption takes place in In0.4Ga0.6As quantum dots (QDs) and the excited electrons are collected by resonant tunneling across an Al0.2Ga0.8As∕In0.1Ga0.9As∕Al0.2Ga0.8As double barrier coupled to the QDs. The field dependent tunneling for excited carriers in T-QDIP is used to select the operating wavelength. This T-QDIP detector exhibits three distinct response peaks at 4.5∕4.9±0.05, 9.5±0.05, and 16.9±0.1μm up to 80K. The peak detectivity is in the range of (1.0–6.0)×1012Jones at 50K. Bias polarity allows the selection of either the 9.5μm or the 16.9μm peak.
Nanosized crystallites of charge-transfer complex of 9-methylanthracene and 1,2,4,5-tetracyanobenzene for bright and optically anisotropic fluorescent probes
Authors: Hosaka Noriko , Obata Masahiro , Suzuki Motohiko , Saiki Toshiharu , Takeda Kenji , Kuwata-Gonokami Makoto
Published: March 2008

Nanocrystallites of charge-transfer (CT) complexes with an average size of 20–40nm were synthesized from ethyl acetate solutions of 9-methylanthracene and 1,2,4,5-tetracyanobenzene by means of spin coating. The optical properties of nanocrystallites were investigated by dark-field and fluorescence imagings. No blinking behavior was observed. Fluorescence brightness and photostability comparable to a standard dye-doped polystyrene sphere were confirmed. We found a pronounced dependence of fluorescence intensity on the polarization of excitation light due to optical anisotropy of the nanocrystallites. The results indicate that the CT nanocrystallite is a promising tool for the observation of rotational motion of nanoobjects in nanofluidics.
Effects of Si passivation on Ge metal-insulator-semiconductor interface properties and inversion-layer hole mobility
Authors: Taoka Noriyuki , Harada Masatomi , Yamashita Yoshimi , Yamamoto Toyoji , Sugiyama Naoharu , Takagi Shin-ichi
Published: March 2008

The impact of Si passivation (SP) on Ge metal-insulator-semiconductor interface properties and the inversion-layer mobility of Ge p-type metal-insulator-semiconductor field effect transistors (PMISFETs) were investigated by using the devices with different thicknesses of the SP layers. SP was effective in decreasing the total charged centers instead of the interface traps. As a result, the inversion-layer hole mobility of the Ge MISFET was significantly improved by introducing the SP layers of the appropriate thickness. This improvement is attributable to the reduction of the amount of the interface charges and the separation of the positions of mobile carriers and the interface charges by the SP layers.
Second-harmonic generation of ultrasonic guided wave propagation in an anisotropic solid plate
Authors: Deng Mingxi
Published: March 2008

The nonlinear effect of primary ultrasonic guided wave propagation in an anisotropic solid plate is analyzed. The formal solution of the corresponding second-harmonic displacement field is presented. The analytical results clearly indicate that the elastic anisotropy of the plate material can, in several aspects, influence the efficiency of generation of second harmonic by primary guided wave propagation, and that the corresponding second harmonic is highly sensitive to the elastic anisotropy of the plate material. The results obtained may provide a potential for accurately characterizing the elastic anisotropy of the plate material with the effect of second-harmonic generation by ultrasonic guided wave propagation.
Phosphorus doped ZnO light emitting diodes fabricated via pulsed laser deposition
Authors: Kim H. S. , Lugo F. , Pearton S. J. , Norton D. P. , Wang Yu-Lin , Ren F.
Published: March 2008

ZnO-based light emitting diodes were fabricated on c-plane sapphire using ZnO:P∕Zn0.9Mg0.1O∕ZnO∕Zn0.9Mg0.1O∕ZnO:Ga p-i-n heterostructures. The p-i-n heterojunction diodes are rectifying and show light emission under forward bias. The electroluminescence spectra shows deep level emission at low bias, but near band edge ultraviolet emission at high voltage bias. A decrease in leakage currents in as-fabricated structures was achieved via low temperature oxygen annealing.
Systematic studies of the photoluminescence of Ge quantum dots grown on strained Si0.7Ge0.3 buffer layer
Authors: Yang Hongbin , Tao Zhensheng , Lin Jianhui , Lu Fang , Jiang Zuimin , Zhong Zhenyang
Published: March 2008

The temperature and the power dependent photoluminescence (PL) of two types of Ge quantum dots (QDs) (small hut cluster and large dome) coincidentally grown on a strained Si0.7Ge0.3 buffer layer were systematically studied. Two PL peaks from the two types of QDs are demonstrated and show different behaviors with increasing temperature. Under low excitation power, the intensity and the energy position of PL peak from small QDs have maximum values at a mediate temperature. Such anomalous behaviors of PL spectra are qualitatively explained by a model based on thermally activated resonant tunneling of holes from large QDs to small QDs.
Anomalous increase in hot-carrier-induced threshold voltage shift in n-type drain extended metal-oxide-semiconductor transistors
Authors: Chen Jone F. , Chen Shiang-Yu , Lee J. R. , Wu Kuo-Ming , Huang Tsung-Yi , Liu C. M.
Published: March 2008

Anomalous increase in positive threshold voltage shift (ΔVT) in n-type drain extended metal-oxide-semiconductor (DEMOS) transistors stressed under high drain voltage and gate voltage is observed. Charge pumping data and technology computer-aided-design simulations reveal that hot-electron injection and trapping in the gate oxide above channel region is responsible for ΔVT. Enhanced impact ionization rate resulted from the presence of large amount of negative oxide charge in channel region is identified to be the main mechanism for anomalous increase in ΔVT. From the results presented in this letter, hot-carrier-induced anomalous increase in ΔVT can become a serious reliability concern in DEMOS transistors.
Quantum chemical study of the initial surface reactions of atomic layer deposition GaAs for photonic crystal fabrication
Authors: Dong Lin , Sun Qing-Qing , Shi Yu , Liu Han , Wang Chen , Ding Shi-Jin , Zhang David Wei
Published: March 2008

III-V materials such as GaAs, GaP, and InP are deposited by atomic layer depostion (ALD) to form inverse opal due to their modifiable intrinsic optoelectronic properties, thus active photonic devices are possible to fabricate. ALD GaAs on the hydroxylated SiO2 surface was investigated under the framework of density functional theory. Our calculation results show that both half-reactions are thermodynamically and kinetically favored, exothermic by 33.73 and 25.90kcal∕mol compared to the reactants. However, longer AsH3 pulse time during the second half cycle of ALD procesis recommended since there is a high activation energy barrier existing in the second half cycle.
Distribution of modern diatom assemblages among small playas
Authors: Boggs D. A. , Gell P. , Eliot I. , Knott B.
Published: March 2008

Diatom diversity of six small playa lakes within the Yarra Yarra drainage system, Western Australia, and the environmental variables likely to influence their distribution was investigated. Thirty-one pennate diatom taxa were identified. Taxa consisted of facultative planktonic and periphytic, circumneutral to alkaliphilous or pH-indifferent forms with known adaptations to saline conditions and fluctuations in salinity in NaCl dominated waters. Data were analysed by ordination (MDS and PCA), hierarchical clustering (CLUSTER), permutation-based hypothesis testing (ANOSIM) and comparative tests on similarity matrices (RELATE). Water depth accounted for the majority of variation in the environmental data. REALTE comparisons of environmental and taxa data did not produce a significant correlation value. We propose that the poor concurrence of the datasets was influenced by the wide ecological tolerances of the taxa recorded, some crucial unmeasured environmental variable/s, possible geographical regionalisation and/or unsampled taxa variability owing to the stochastic nature of the wetlands. Broad patterns of distribution were related to hydroperiod and some taxa groups were loosely associated with environmental groups consistent with established ecological tolerances for the taxa.
Species-specific changes in tissue morphogenesis induced by two arthropod leaf gallers in Lantana camara L. (Verbenaceae)
Authors: Moura Maria Zabelê Dantas , Soares Geraldo Luiz Gonçalves , Isaias Rosy Mary dos Santos
Published: March 2008

When different cecidogenous species attack the same plant species, each one causes distinct plant tissue reorganisation, and forms typical gall structures. Two Lantana camara L. leaf galls induced by Aceria lantanae (Cook) (Acarina: Eriophyidae) and Schismatodiplosis lantanae (Rübsaamen) (Diptera: Cecidomyiidae) were collected in a subspontaneous population at Rio Grande do Sul, Brazil. A. lantanae crinckle galls were uni- or multi-chambered and contained several mites, caused by several leaf foldings, and consisted of hyperplasic epidermis and parenchyma. S. lantanae induced uni-chambered pouch galls inhabited by one larvae or pupa. This gall consisted predominantly of hypertrophied spongy parenchyma. Our results documented how these herbivores acted in cells with the same initial morphogenetic competence, altering leaf pattern, and inducing their specific extended phenotype.
Aestivation organ structure in Drosera subgen. Ergaleium (Droseraceae): corms or tubers; roots or shoots?
Authors: Conran John G.
Published: March 2008

The nature of the subterranean aestivation organ in Drosera subgen. Ergaleium is reinvestigated and expanded across a wider range of taxa. The structure is confirmed to be anatomically and developmentally a stem tuber, and the adventitious growths arising along the subterranean stem are confirmed as roots. The enveloping, multi-layered, tunicate, corm-like sheath seen in some species is of epidermal and not of leaf origin, so that the structure is a tuberous condensed rhizome and not a corm. Nevertheless, the resulting structures appear to function ecologically as corms, the sheaths possibly protecting the dormant tubers from dehydration, and/or the abundant droserone pigment in the sheath tissues acting to deter fungi and other organisms. Similarly, the adventitious root-like structures on the stems are found to be anatomically roots, albeit lacking a developed root cap, and to possess well developed, epidermally derived root hairs, contrary to the suggestion of some studies that the ‘hairs’ were ectomycorrhizal hyphae. However, many Ergaleium species have no sheaths, or use remnant stem and/or root tissues, and some other species appear to show sheath-related hyphal associations, and highly reduced roots with few or no obvious root hairs. Thus, the ecological strategies involving these structures remain an area for further study.
Floral development and breeding systems of Dryandra sessilis and Grevillea wilsonii (Proteaceae)
Authors: Collins Brian G. , Walsh Michelle , Grey James
Published: March 2008

Dryandra sessilis (Knight) Domin. and Grevillea wilsonii A.Cunn. co-occur on lateritic soils in the jarrah forest of Western Australia, with their flowering seasons overlapping for several months during winter and spring. Both species are protandrous, with pollen presentation occurring 1–2 days before the stigmas of individual flowers become receptive. Peak receptivity, as indicated by maximum peroxidase secretion, coincides with the maximum opening of stigmatic grooves for D. sessilis or maximum elevation of the stigmatic papillae in G. wilsonii. Pollinators such as western wattlebirds, New Holland honeyeaters and western spinebills almost exclusively visit flowers or inflorescences at times when large amounts of nectar are present, and when self-pollen is available for transfer or stigmas are receptive to the deposition of pollen. By foraging in this manner, yet still moving frequently between plants and inflorescences, honeyeaters that visit D. sessilis should guarantee an effective spread of pollen. The overall level of fruiting success achieved by this species is considerably higher than that for G. wilsonii, a species whose flowers are visited much less often than those of D. sessilis. Allozyme analysis, artificial pollination experiments and the calculation of pollen : ovule ratios indicate that D. sessilis is essentially an obligate outcrosser, at least in locations where plant densities are high, whereas G. wilsonii has a mixed mating system that allows it to set fruits as a consequence of either selfing or outcrossing. Potential fruit-set is low for both species, with post-zygotic incompatibility mechanisms mediated by the availability of nutritional resources thought to be at least partly responsible for the even lower levels of final fruit-set. Total fruit and seed production by individual plants is much greater for D. sessilis than for G. wilsonii, and possibly a reflection of differences in the regeneration requirements of the two species after environmental disturbance such as fire.
Extraction of high-quality tissue-specific RNA from London plane trees (Platanus acerifolia), permitting the construction of a female inflorescence cDNA library
Authors: Li Zhineng , Liu Guofeng , Zhang Jiaqi , Zhang Junwei , Bao Manzhu
Published: March 2008

The London plane tree (Platanus acerifolia Willd.) has global importance as an urban landscaping tree and is the subject of genetic-improvement programs for productive sterility, disease and/or insect resistance. Molecular analysis techniques are crucial to such programs, but may be impeded by specific difficulties encountered during nucleic acid isolation. A detailed RNA isolation and purification protocol, based on established cetyltrimethyl-ammonium bromide (CTAB) extraction techniques combined with additional purification steps using butanol and the ionic detergent CTAB, which overcomes these problems in the woody species P. acerifolia, was conducted. In short, phenolic compounds are bound to soluble polyvinylpyrrolidone and then separated out through LiCl precipitation of the RNA. Subsequently, protein- and carbohydrate-contaminants are removed by chloroform partitioning followed by LiCl-mediated precipitation. The resulting isolates of RNA were found to be of sufficient quality for successful use in reverse transcription PCR analysis. Furthermore, RNA isolates from female inflorescences were used for the construction of a cDNA library. This library was found to contain several full-length cDNA clones of MADS-box genes, consistent with the library being representative of inflorescence expression profiles.
Functional analysis of lactate dehydrogenase during hypoxic stress in Arabidopsis
Authors: Dolferus Rudy , Wolansky Mark , Carroll Rebecka , Miyashita Yo , Ismond Kathleen , Good Allen
Published: March 2008

During waterlogging conditions plants switch from aerobic respiration to anaerobic fermentation to cope with the lack of available oxygen. Plants have two main fermentation pathways: ethanol and lactic acid fermentation. In this paper we carry out a functional analysis of the Arabidopsis lactate dehydrogenase gene, LDH1. Our results indicate that LDH1, like some other anaerobic genes, is expressed in a root-specific manner and is affected by a variety of abiotic stresses (hypoxia, drought, cold) and mechanical wounding. Functional analysis of LDH1 was carried out using transgenic Arabidopsis overexpressing the gene (35S promoter) and a T-DNA knockout line. Overexpression of LDH1 resulted in improved survival of low oxygen stress conditions in roots but not in shoots. Increased lactic acid fermentation also resulted in significantly higher activities of pyruvate decarboxylase (PDC). Knockout mutants of LDH1 showed reduced survival under low oxygen conditions and PDC activity levels were not changed compared with the wild type. Our data suggest that there is an interdependency between the lactic and ethanol fermentation pathways and that lactic acid fermentation may play a role in stimulating ethanol fermentation and improving plant survival. We show also that Arabidopsis plants are able to exude lactate efficiently into the medium, preventing it accumulating to toxic levels in the cells.
Do stomata operate at the same relative opening range along a canopy profile of Betula pendula?
Authors: Eensalu Eve , Kupper Priit , Sellin Arne , Rahi Märt , Sõber Anu , Kull Olevi
Published: March 2008

Stomatal density and size were measured along the light gradient of a Betula pendula Roth. canopy in relation to microclimatic conditions. The theoretical stomatal conductance was calculated using stomatal density and dimensions to predict to what degree stomatal conductance is related to anatomical properties and relative stomatal opening. Stomatal density was higher and leaf area smaller in the upper canopy, whereas epidermal cell density did not change significantly along the canopy light gradient, indicating that stomatal initiation is responsible for differences in stomatal density. Stomatal dimensions – the length of guard cell on the dorsal side and the guard cell width – decreased with declining light availability. Maximum measured stomatal conductance and modelled stomatal conductance were higher at the top of the crown. The stomata operate closer to their maximum openness and stomatal morphology is a more important determinant of stomatal conductance in the top leaves than in leaves of lower canopy. As stomata usually limit photosynthesis more in upper than in lower canopy, it was concluded that stomatal morphology can principally be important for photosynthesis limitation in upper canopy.
Formulas for primitive idempotents in Frobenius algebras and an application to decomposition maps
Authors: Neunhöffer Max , Scherotzke Sarah
Published: March 2008

In the first part of this paper we present explicit formulas for primitive idempotents in arbitrary Frobenius algebras using the entries of representing matrices coming from projective indecomposable modules with respect to a certain choice of basis. The proofs use a generalisation of the well-known Frobenius-Schur relations for semisimple algebras.

The second part of this paper considersO\mathcal {O}-freeO\mathcal {O}-algebras of finiteO\mathcal {O}-rank over a discrete valuation ringO\mathcal {O}and their decomposition maps under modular reduction modulo the maximal ideal ofO\mathcal {O}, thereby studying the modular representation theory of such algebras.

Using the formulas from the first part we derive general criteria for such a decomposition map to be an isomorphism that preserves the classes of simple modules involving explicitly known matrix representations on projective indecomposable modules.

Finally, we show how this approach could eventually be used to attack a conjecture by Gordon James in the formulation of Meinolf Geck for Iwahori-Hecke algebras, provided the necessary matrix representations on projective indecomposable modules could be constructed explicitly.
Evolution and Religious Creation Myths
Authors: Lurquin Paul F. , Stone Linda
Published: March 2008

Intelligent Design (ID) thinking and older style creationism argue that evolution by natural selection is an incorrect theory. This book demonstrates that in doing so, neocreationism (Intelligent Design) and classical creationism misinterpret the meaning of scientific theories. This is because these religious doctrines imply teleology and purpose in the natural world, which are not analyzable scientifically. In addition, the concept of “irreducible complexity” often invoked by ID proponents is based on a flawed interpretation of scientific data. It also demonstrates that evolutionary thinking in the sciences is a powerful tool that can be used in the study of the origin of the universe, the origin of life and its diversification, and human evolution. Creationism and ID do not belong in the realm of science and have contributed nothing to its advancement. Further, attempts to force the teaching of creationism and ID in schools can only weaken a science curriculum which already leaves much to be desired.
Feeding of mature cod (Gadus morhua) on the spawning grounds in Lofoten
Authors: Michalsen Kathrine , Johannesen Edda , Bogstad Bjarte
Published: March 2008

Michalsen, K., Johannesen, E., and Bogstad, B. 2008. Feeding of mature cod (Gadus morhua) on the spawning grounds in Lofoten. – ICES Journal of Marine Science, 65: 571–580. Many authors state that cod (Gadus morhua) do not feed during the spawning period. However, this more or less established fact has rarely been investigated in the field. Here, the content of stomachs from Northeast Arctic cod (NEAC) and Norwegian coastal cod (NCC) sampled from the spawning ground in Lofoten were examined over a 10-year period (1996–2006). The occurrence of food in the stomachs of spawning cod, stomach fullness, diet composition, and variation in these variables between NEAC and NCC, year, and sex were analysed and compared. The analysis shows that cod do feed, even when they are in a spawning state. NCC had a lower proportion of empty stomachs and the stomachs were fuller than those from NEAC. Females had a lower proportion of empty stomachs than males and their stomachs were in general fuller. Herring (Clupea harengus) dominated the diet of cod. However, cod consumption of herring on the spawning grounds seems to be a minor source of mortality on herring. Although spawning cod do feed, the proportion of empty stomachs was higher and stomach fullness was lower than in stomachs of NEAC from the Barents Sea.
Reproduction and feeding of Sagitta enflata in the Humboldt Current system off Chile
Authors: Giesecke Ricardo , González Humberto E.
Published: March 2008

Giesecke, R., and González, H. E. 2008. Reproduction and feeding of Sagitta enflata in the Humboldt Current system off Chile. – ICES Journal of Marine Science, 65: 361–370. This study is based on 3 years (August 2002–July 2005) of monthly zooplankton sampling at a fixed station located 18 km off Coliumo Bay (36°S), Chile. The reproduction of Sagitta enflata, its feeding rate, specific daily ration, and prey selectivity were analysed and related to several environmental variables: temperature, salinity, dissolved oxygen, chlorophyll a concentrations, and both meso- and micro-zooplankton abundance. The main predatory activity of S. enflata was centred on the copepods Paracalanus parvus, Oithona spp., and Calanus chilensis. These three species were consumed at different rates, depending mainly on the maturity of the S. enflata population. When Stages I and II individuals dominated, predation focused on the small P. parvus and Oithona spp., whereas more mature populations (Stages III and IV) preyed selectively on C. chilensis. The mean specific daily ration of 0.1 d−1 increased to 0.5 d−1 before and during maturation. The reproductive phase of S. enflata was closely coupled with the abundance of nauplii, suggesting that chaetognath reproduction paralleled that of copepods, most likely to diminish the mortality of its offspring resulting from starvation. The relationships between these were included in a conceptual model and their ecological significance is discussed.
Temperature until the ‘eyed stage’ of embryogenesis programmes the growth trajectory and muscle phenotype of adult Atlantic salmon
Authors: Macqueen Daniel J , Robb David H.F , Olsen Tom , Melstveit Linda , Paxton Charles G.M , Johnston Ian A
Published: March 2008

We investigated how adult growth in Atlantic salmon (Salmo salarL.) was affected by changing embryonic temperature from fertilization until the completion of eye pigmentation. Fertilized eggs from several hundred families were divided between four temperature treatments (2, 5, 8 or 10°C) and subsequently reared in identical conditions in replicated tanks. Fish exposed to 2 and 5°C treatments were significantly smaller at smoltification than groups at higher temperatures, but showed substantial compensatory catch-up growth. Remarkably, temperature during this short window of embryogenesis dictated adult myogenic phenotype three years later with significant treatment effects on the muscle fibre final number (FFN), maximum diameter, nuclear density and size distribution. FFN was highest for the 5°C treatment and was reduced at higher and lower treatment temperatures. Our results require direct temperature effects on embryonic tissues, such as the stem cell-containing external cell layer, in order to produce persistent effects on juvenile and adult growth.
The effect of geometry on three-dimensional tissue growth
Authors: Rumpler Monika , Woesz Alexander , Dunlop John W.C , van Dongen Joost T , Fratzl Peter
Published: March 2008

Tissue formation is determined by uncountable biochemical signals between cells; in addition, physical parameters have been shown to exhibit significant effects on the level of the single cell. Beyond the cell, however, there is still no quantitative understanding of how geometry affects tissue growth, which is of much significance for bone healing and tissue engineering. In this paper, it is shown that the local growth rate of tissue formed by osteoblasts is strongly influenced by the geometrical features of channels in an artificial three-dimensional matrix. Curvature-driven effects and mechanical forces within the tissue may explain the growth patterns as demonstrated by numerical simulation and confocal laser scanning microscopy. This implies that cells within the tissue surface are able to sense and react to radii of curvature much larger than the size of the cells themselves. This has important implications towards the understanding of bone remodelling and defect healing as well as towards scaffold design in bone tissue engineering.
A community change in the algal endosymbionts of a scleractinian coral following a natural bleaching event: field evidence of acclimatization
Authors: Jones A.M , Berkelmans R , van Oppen M.J.H , Mieog J.C , Sinclair W
Published: March 2008

The symbiosis between reef-building corals and their algal endosymbionts (zooxanthellae of the genus
Symbiodinium
) is highly sensitive to temperature stress, which makes coral reefs vulnerable to climate change. Thermal tolerance in corals is known to be substantially linked to the type of zooxanthellae they harbour and, when multiple types are present, the relative abundance of types can be experimentally manipulated to increase the thermal limits of individual corals. Although the potential exists for this to translate into substantial thermal acclimatization of coral communities, to date there is no evidence to show that this takes place under natural conditions. In this study, we show field evidence of a dramatic change in the symbiont community of
Acropora millepora
, a common and widespread Indo-Pacific hard coral species, after a natural bleaching event in early 2006 in the Keppel Islands (Great Barrier Reef). Before bleaching, 93.5% (
n
=460) of the randomly sampled and tagged colonies predominantly harboured the thermally sensitive
Symbiodinium
type C2, while the remainder harboured a tolerant
Symbiodinium
type belonging to clade D or mixtures of C2 and D. After bleaching, 71% of the surviving tagged colonies that were initially C2 predominant changed to D or C1 predominance. Colonies that were originally C2 predominant suffered high mortality (37%) compared with D-predominant colonies (8%). We estimate that just over 18% of the original
A. millepora
population survived unchanged leaving 29% of the population C2 and 71% D or C1 predominant six months after the bleaching event. This change in the symbiont community structure, while it persists, is likely to have substantially increased the thermal tolerance of this coral population. Understanding the processes that underpin the temporal changes in symbiont communities is key to assessing the acclimatization potential of reef corals.
Effects of metabolic level on the body size scaling of metabolic rate in birds and mammals
Authors: Glazier Douglas S
Published: March 2008

Metabolic rate is traditionally assumed to scale with body mass to the 3/4-power, but significant deviations from the ‘3/4-power law’ have been observed for several different taxa of animals and plants, and for different physiological states. The recently proposed ‘metabolic-level boundaries hypothesis’ represents one of the attempts to explain this variation. It predicts that the power (log–log slope) of metabolic scaling relationships should vary between 2/3 and 1, in a systematic way with metabolic level. Here, this hypothesis is tested using data from birds and mammals. As predicted, in both of these independently evolved endothermic taxa, the scaling slope approaches 1 at the lowest and highest metabolic levels (as observed during torpor and strenuous exercise, respectively), whereas it is near 2/3 at intermediate resting and cold-induced metabolic levels. Remarkably, both taxa show similar, approximately U-shaped relationships between the scaling slope and the metabolic (activity) level. These predictable patterns strongly support the view that variation of the scaling slope is not merely noise obscuring the signal of a universal scaling law, but rather is the result of multiple physical constraints whose relative influence depends on the metabolic state of the organisms being analysed.