bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of stable titanium germanosilicide thin films on Si1−xGex
Authors: Burnette James E. , Nemanich Robert J. , Sayers Dale E.
Published: May 2005

The sequential deposition of strained Si1−xGex with concentrations x=0.20 and 0.30, amorphous silicon, and titanium on Si (100) after annealing at 700°C leads to the formation of a C54 Ti(Si1−yGey)2∕Si1−xGex bilayer, the phase formation and interface stability of which are studied. The use of an amorphous layer of Si is employed to eliminate or decrease the formation of germanium-rich Si1−zGez alloy precipitates found in the solid-phase reaction of Ti and Si1−xGex. It has been proposed that the precipitation phenomenon was driven by differences in the enthalpy of formation as a function of concentration in the Ti(Si1−yGey)2 layer, resulting from the enthalpy difference between TiSi2 and TiGe2 compounds, both of which are assumed to be completely miscible with one another. Layers of amorphous silicon of varying thicknesses were incorporated between a 300-Å Ti layer and the strained Si1−xGex substrate layer to achieve Ti(Si1−yGey)2 films that are in equilibrium with the Si1−xGex substrate. The use of amorphous silicon layers of varying thicknesses indicated that Ti(Si1−yGey)2∕Si1−xGex films could be formed with the absence of germanium-rich precipitates at the grain boundaries, depending on the amorphous silicon layer thickness.
Plasma damage-free sputtering of indium tin oxide cathode layers for top-emitting organic light-emitting diodes
Authors: Kim Han-Ki , Kim D.-G. , Lee K.-S. , Huh M.-S. , Jeong S. H. , Kim K. I. , Seong Tae-Yeon
Published: May 2005

We report on plasma damage-free sputtering of an indium tin oxide (ITO) cathode layer, which was grown by a mirror shape target sputtering (MSTS) technique, for use in top-emitting organic light-emitting diodes (TOLEDs). It is shown that OLEDs with ITO cathodes deposited by MSTS show much lower leakage current (9.2×10−5mA∕cm2) at reverse bias of −6V as compared to that (1×10−1–10−2mA∕cm2 at −6V) of OLEDs with ITO cathodes grown by conventional dc magnetron sputtering. Based on high-resolution electron microcopy, x-ray diffraction, and scanning electron microscopy results, we describe a possible mechanism by which plasma damage-free ITO films are grown and their application for TOLEDs.
Nucleation site and mechanism leading to growth of bulk-quantity Mn3O4 nanorods
Authors: Chen Z. W. , Lai J. K. L. , Shek C. H.
Published: May 2005

We report a simple and effective method for the generation of bulk-quantity nanorods of manganese oxide, Mn3O4, under surroundings of a suitable surfactant and alkaline solution. It is found that the Mn3O4 nanorod is smooth, straight, and that the geometrical shape is structurally perfect, which is produced with lengths from several hundreds nanometers to a few micrometers, and diameters range from 10nmto30nm. We amazedly found that the dripping speed of the NaOH solution plays an important role in formation of bulk-quantity Mn3O4 nanorods. The difference of dripping speed of the NaOH solution leads to a large difference of Mn3O4 morphologies, which is observed in the transmission electron microscopy images. The growth of the Mn3O4 nanorods is suggested first to follow a self-catalyzed solution-liquid-solid mechanism.
Fabrication of wide-band-gap MgxZn1−xO quasi-ternary alloys by molecular-beam epitaxy
Authors: Tanaka Hiroshi , Fujita Shigeo , Fujita Shizuo
Published: May 2005

A series of wurtzite MgZnO quasi-ternary alloys, which consist of wurtzite MgO∕ZnO superlattices, were grown by molecular-beam epitaxy on sapphire substrates. By changing the thicknesses of ZnO layers and/or of MgO layers of the superlattice, the band-gap energy was artificially tuned from 3.30to4.65eV. The highest band gap, consequently realized by the quasi-ternary alloy, was larger than that of the single MgZnO layer, we have ever reported, keeping the wurtzite structure. The band gap of quasi-ternary alloys was well analyzed by the Kronig–Penny model supposing the effective masses of wurtzite MgO as 0.30m0 and (1–2)m0 for electrons and holes, respectively.
A quantum wave-packet study of intersystem crossing effects in the O(P2,1,3,D21)+H2 reaction
Authors: Chu Tian-Shu , Zhang Xin , Han Ke-Li
Published: May 2005

We present for the first time an exact quantum study of spin–orbit-induced intersystem crossing effects in the title reaction. The time-dependent wave-packet method, combined with an extended split operator scheme, is used to calculate the fine-structure resolved cross section. The calculation involves four electronic potential-energy surfaces of the A′1 state [J. Dobbyn and P. J. Knowles, Faraday Discuss. 110, 247 (1998)], the A′3 and the two degenerate A″3 states [S. Rogers, D. Wang, A. Kuppermann, and S. Wald, J. Phys. Chem. A 104, 2308 (2000)], and the spin–orbit couplings between them [B. Maiti, and G. C. Schatz, J. Chem. Phys. 119, 12360 (2003)]. Our quantum dynamics calculations clearly demonstrate that the spin–orbit coupling between the triplet states of different symmetries has the greatest contribution to the intersystem crossing, whereas the singlet-triplet coupling is not an important effect. A branch ratio of the spin state Π3∕2 to Π1∕2 of the product OH was calculated to be ∼2.75, with collision energy higher than 0.6eV, when the wave packet was initially on the triplet surfaces. The quantum calculation agrees quantitatively with the previous quasiclassical trajectory surface hopping study.
Analysis of conducting-system frequency response data for an interfacial amorphous phase of copper-core oxide-shell nanocomposites
Authors: Macdonald J. R. , Basu S. , Chakravorty D.
Published: May 2005

Complex electrical-conductivity experimental data sets for the interfacial amorphous phase in copper-core–copper-oxide-shell nanostructured composites have been analyzed using two Kohlrausch-related frequency response models recently developed for analysis of the dispersive electrical response of conductive materials. Such analysis has been carried out for both the precursor (herein referred to as the reference) glass as well as the glass in which the core-shell nanostructure was developed after suitable heat treatment. Complex nonlinear-least-squares data fitting at each temperature employed composite Kohlrausch models that included electrode effects. Because of the lack of sufficient high-frequency data, it was necessary to use fixed, rather than free, values of the shape parameter β1 of the model. On the basis of topological considerations, its values were set at 1∕3 and 2∕3 for the reference glass and the core-shell structured glass, respectively. The activation energies of resistivity for the reference and the treated glasses were found to have values of about 2 and 0.4eV, respectively, indicating two different mechanisms of electrical conduction. A blocking-electrode measurement on the reference glass indicated the presence of an electronic as well as an ionic component of the electrical conductivity, with the ionic part dominating at the temperatures for which the present analyses were carried out.
Role of Cu in dissolution kinetics of Cu metallization in molten Sn-based solders
Authors: Huang M. L. , Loeher T. , Ostmann A. , Reichl H.
Published: May 2005

The focus of this study is on the role of Cu content in the dissolution kinetics of Cu in high-Sn solders during the solid/liquid reaction accompanied by interfacial intermetallic compound formation. Small additions of Cu (0.7%, 1.5%) in high-Sn solders dramatically decrease the dissolution rate of Cu at low temperatures. Sn-3.5Ag, as expected, has a dissolution rate similar to that of pure Sn. The difference in dissolution rate of Cu in various molten solders is explained in terms of the solubility limit of Cu in molten solders based on the Cu-Sn phase diagram. The correlation between the metallurgical aspects of interfacial η(Cu6Sn5) phase formation and dissolution kinetics of Cu in molten solders leads to an understanding of the mechanism that controls the dissolution rate of Cu in molten solders.
Buckling analysis of triple-walled carbon nanotubes embedded in an elastic matrix
Authors: Kitipornchai S. , He X. Q. , Liew K. M.
Published: May 2005

Explicit formulas are obtained to describe the buckling behavior of triple-walled carbon nanotubes (CNTs) that are embedded in an elastic matrix, with van der Waals (vdW) interaction taken into consideration. The investigation is based on the continuum shell theory in which the individual tube is treated as a cylindrical shell. The elastic matrix surrounding the outermost tube is modeled as a Pasternak foundation to account for not only the normal stress, but also the shear stress between the outermost tube and the surrounding matrix. Numerical analyses are carried out to estimate the critical buckling load of triple-walled CNTs, and the results indicate that the critical buckling loads approach a constant of around 0.26N∕m with the increase of the innermost radii regardless of whether or not the triple-walled CNT is embedded in an elastic matrix. The effects of vdW interactions before and after buckling on the critical buckling load are also examined for triple-walled CNTs with various innermost radii.
Effect of interphase mixing on the structure of calcium silicate intergranular film/silicon nitride crystal interfaces
Authors: Su Xiaotao , Garofalini Stephen H.
Published: May 2005

Molecular-dynamics simulations of intergranular films (IGF) containing Si, O, N, and Ca in contact with Si3N4 surfaces containing different levels of interface mixing of the species from the IGF with the crystal surfaces were performed using a multibody interatomic potential. This mixing is equivalent to the formation of a roughened silicon oxynitride crystal surface. With significant interphase mixing at the crystal surfaces, less ordering into the IGF caused by the compositionally modified oxynitride interfaces is observed. Such results are in contrast to our earlier data that showed significant ordering into the IGF induced by the ideally terminated crystal surfaces with no interphase mixing. In all cases, the central position of the first peak in the Si-O pair distribution function (PDF) at the interface ranges from 1.62 to 1.64 Å, consistent with recent experimental findings. The central position of the first peak in the Si-N PDF ranges from 1.72 to 1.73 Å, consistent with experimental results. With increased interphase mixing, the intensity as well as the area of the first peak of the Si-O and Si-N PDFs for Si attached to the crystal decreases, indicating the decrease of coordination number of O or N with these silicon. Such combined decrease in coordination indicates a significant remnant of vacancies in the crystal surfaces due to the exchange process used here. The results imply a significant effect of interface roughness on the extent of ordering in the amorphous IGF induced by the crystal surface.
An exact solution of the five-dimensional Einstein equations with four-dimensional de Sitter-like expansion
Authors: Liko Tomáš , Wesson Paul S.
Published: May 2005

We present an exact solution to the Einstein field equations which is Ricci and Riemann flat in five dimensions, but in four dimensions is a good model for the early vacuum-dominated universe.
Summation of divergent series and Borel summability for strongly dissipative differential equations with periodic or quasiperiodic forcing terms
Authors: Gentile Guido , Bartuccelli Michele V. , Deane Jonathan H. B.
Published: May 2005

We consider a class of second order ordinary differential equations describing one-dimensional systems with a quasiperiodic analytic forcing term and in the presence of damping. As a physical application one can think of a resistor–inductor–varactor circuit with a periodic (or quasiperiodic) forcing function, even if the range of applicability of the theory is much wider. In the limit of large damping we look for quasiperiodic solutions which have the same frequency vector of the forcing term, and we study their analyticity properties in the inverse of the damping coefficient. We find that even the case of periodic forcing terms is nontrivial, as the solution is not analytic in a neighborhood of the origin: it turns out to be Borel summable. In the case of quasiperiodic forcing terms we need renormalization group techniques in order to control the small divisors arising in the perturbation series. We show the existence of a summation criterion of the series in this case also; however, this cannot be interpreted as Borel summability.
Generation of narrow-band terahertz radiation with preset frequency components in poled ferroelectric materials
Authors: Liu Xin-Hai , Wu Jian , Duan Wenhui , Gu Bing-Lin
Published: May 2005

We investigate theoretically the generation of narrow-band, multifrequency terahertz (THz) radiation via optical rectification of femtosecond laser pulses in poled ferroelectric materials. We propose a method based on simulated annealing (SA) algorithm to inversely determine the needed ferroelectric domain structure for generating the expected THz radiation. We demonstrate that multifrequency THz radiation with arbitrarily preset frequencies and relative intensities can be generated from appropriate domain structures determined by this SA-based method. The designed domain structure has a good performance stability with respect to the random fluctuation of the domain thicknesses.
Stress-driven thermohaline loops
Authors: Yuan Shaoyu , Wunsch Carl
Published: May 2005

The two-state Stommel box model, commonly invoked as an ocean circulation analog, is dynamically equivalent to a one-dimensional fluid loop (called “loop-Stommel” models). Although it dominates the energy input to the ocean circulation, the wind stress is usually omitted from the discussion. Here we briefly explore the behavior of loop-Stommel models in the presence of stress, with both thermal and salinity sources. Although the unstable (Rayleigh–Bénard) configuration is considered, most interest lies with buoyancy sources at the same geopotential (type 3 convection). In addition to the nondimensional stress, the multiple solutions depend upon the Rayleigh and Prandtl numbers with the latter primarily determining the stability of the possible steady states. Salinity forcing in a double-diffusive configuration introduces another stable mode.
Fermi-level band filling and band-gap renormalization in Ga-doped ZnO
Authors: Ye J. D. , Gu S. L. , Zhu S. M. , Liu S. M. , Zheng Y. D. , Zhang R. , Shi Y.
Published: May 2005

The fundamental optical properties of Ga-doped ZnO films grown by metalorganic chemical vapor deposition were investigated by room-temperature transmittance and photoluminescence (PL) spectroscopy. The Burstein–Moss (BM) shift of the absorption edge energy is observed at the carrier concentration up to 2.47×1019cm−3. The absorption edges are fitted to a comprehensive model based on the electronic energy-band structure near critical points plus relevant discrete and continuum excitonic effects, taking account of the Fermi-level filling factor. The theoretical calculation for BM effect is in good agreement with the experimental facts, considering the nonparabolic nature of conduction-band and band-gap renormalization (BGR) effects. Meanwhile, the monotonic redshift of the near-band-gap emission detected by PL measurements has also been observed with increasing free-carrier concentration, which is attributed to the BGR effects, and can be fitted by an n1∕3 power law with a BGR coefficient of 1.3×10−5meVcm.
Experimental imaging of silicon nanotubes
Authors: De Crescenzi M. , Castrucci P. , Scarselli M. , Diociaiuti M. , Chaudhari Prajakta S. , Balasubramanian C. , Bhave Tejashree M. , Bhoraskar S. V.
Published: May 2005

Transmission electron microscopy (TEM), electron energy loss near edge structures (EELNES) and scanning tunneling microscopy (STM) were used to distinguish silicon nanotubes (SiNT) among the reaction products of a gas phase condensation synthesis. TEM images exhibit the tubular nature with a well-defined wall. The EELNES spectra performed on each single nanotube show that they are constituted by nonoxidized silicon atoms. STM images show that they have diameter ranging from 2 to 35 nm, have an atomic arrangement compatible with a puckered structure and different chiralities. Moreover, the I-V curves showed that SiNT can be semiconducting as well as metallic in character.
Elastic behavior during early stage of β phase decomposition in a Cu–Al–Ni shape memory alloy
Authors: Recarte V. , Pérez-Landazábal J. I. , Sánchez-Alarcos V.
Published: May 2005

The precipitation of γ1 phase modifies the characteristics of the martensitic transformation in Cu-based shape memory alloys. In the early stage of decomposition, the knowledge of elastic constants of γ1 phase is of special interest due to the elastic interaction between martensite interfaces and precipitates. In this letter, neutron powder diffraction, differential scanning calorimetry, and accurate resonant ultrasound spectroscopy allow us to determine two different stages at the beginning of the γ1 phase precipitation process in a texture-free Cu–Al–Ni shape memory alloy. The elastic constants and Debye temperature of the γ1 phase in Cu–Al–Ni have been determined.
Welwitschia mirabilis: CAM or not CAM — what is the answer?
Authors: von Willert Dieter J. , Armbrüster Nicole , Drees Tobias , Zaborowski Maik
Published: May 2005

After more than 20 years of extensive study we found clear evidence that Welwitschia mirabilis Hook.f. is able to take up CO2 at night in both of its natural ecosystems, the Namib desert and the Mopane savannah, and hence should be classified a crassulacean acid metabolism (CAM) plant. At six different sites, 85 W. mirabilis plants were marked and the growth rate of their leaves and leaf ribbons were measured over a period of 2.5 years. The slowest and the fastest growing plant of these 85 plants were from the Mopane savannah and from the north-west of the Brandberg massif, respectively. These were selected for the gas-exchange measurements of this study. Within the course of a year nocturnal CO2 uptake was found only in December and January when the nights were shortest and plants were flowering. CO2 uptake during the night was not pronounced and never accounted for more than 4% of the total CO2 uptake over 24 h. Maximum rates of nocturnal CO2 uptake never exceeded 0.1 µmol m–2 s–1 for the slowest and 0.2 µmol m–2 s–1 for the fastest growing plant. Neither water availability in the soil nor night temperature was found to determine nocturnal CO2 uptake in terms known for CAM plants. Regardless of the growing site all leaves of W. mirabilis contained high amounts of malic and citric acid. Small increases of acids over night as calculated from the gas exchange measurements are masked by the extremely uneven distribution of these acids in the leaves, making the feature of an overnight malic or citric acid accumulation an unsuited test for CAM in W. mirabilis. An increase in 13C discrimination with increasing distance from the coast was confirmed. Photorespiration was extremely high and followed air temperature around the leaf. Although the debate whether or not W. mirabilis is a CAM plant can be closed, no answer could be given why W. mirabilis makes so little use of CAM.
Distribution of crassulacean acid metabolism in orchids of Panama: evidence of selection for weak and strong modes
Authors: Silvera Katia , Santiago Louis S. , Winter Klaus
Published: May 2005

Crassulacean acid metabolism (CAM) is one of three metabolic pathways found in vascular plants for the assimilation of carbon dioxide. In this study, we investigate the occurrence of CAM photosynthesis in 200 native orchid species from Panama and 14 non-native species by carbon isotopic composition (δ13C) and compare these values with nocturnal acid accumulation measured by titration in 173 species. Foliar δ13C showed a bimodal distribution with the majority of species exhibiting values of approximately –28‰ (typically associated with the C3 pathway), or –15‰ (strong CAM). Although thick leaves were related to δ13C values in the CAM range, some thin-leaved orchids were capable of CAM photosynthesis, as demonstrated by acid titration. We also found species with C3 isotopic values and significant acid accumulation at night. Of 128 species with δ13C more negative than –22‰, 42 species showed nocturnal acid accumulation per unit fresh mass characteristic of weakly expressed CAM. These data suggest that among CAM orchids, there may be preferential selection for species to exhibit strong CAM or weak CAM, rather than intermediate metabolism.
Competitive sorption of metals in water repellent soils: Implications for irrigation recycled water
Authors: Xiong X. , Stagnitti F. , Turoczy N. , Allinson G. , Li P. , Nieber J. , Steenhuis T. S. , Parlange J-Y. , LeBlanc M. , Ziogas A. K. , Ferreira A. J. D. , Keizer J. J.
Published: May 2005

Australia is a water-stressed nation and demand on potable water supply is increasing. Consequently water conservation and reuse are increasingly becoming important. Irrigation of recycled wastewater on water repellent soils is a technology that is being trialled as a means of improving crop production and conserving potable supply. However, recycled water contains potentially harmful heavy metals. This paper reports the competitive sorption and desorption of several common heavy metals found in soils collected from a farm located in the south-east of South Australia. The soil from this location is severely water repellent, but some sites were amended with kaolinite clay (Si4Al4O10(OH)8) about 7 and 15 years ago. The metals studied were Cu, Pb, Cd, Cr, Ni, and Zn. Competitive sorption of the metals was distinctly observed. For all heavy metals, the quantity of metal sorbed was higher in amended soil, and there was a strong correlation between the specific sorption to total sorption ratio and the amount of clay in the soil. The sorption intensities varied with metal, Cr, Pb, and Cu having a high sorption tendencies and Zn, Cd, and Ni having comparatively low sorption tendencies. The total sorption capacity for all metals increased in clay-treated soils compared with non-treated soils. On average, clay-amended water repellent soils had a 20–40% increased capacity to adsorb total metals; however, this increase was largely caused by the increased capacities to adsorb Zn, Cd, and Ni. The effect of clay treatment largely enhanced the sorption capacity of relatively weakly adsorbing heavy metals. The implications for using recycled wastewater on the long-term sustainable agro-environmental management of these soils are discussed.
The T4-encoded cochaperonin, gp31, has unique properties that explain its requirement for the folding of the T4 major capsid protein
Authors: Bakkes Patrick J. , Faber Bart W. , van Heerikhuizen Harm , van der Vies Saskia M.
Published: May 2005

The morphogenesis of bacteriophage T4 requires a specialized bacteriophage-encoded molecular chaperone (gp31) that is essential for the folding of the T4 major capsid protein (gp23). gp31 is related to GroES, the chaperonin of the
Escherichia coli
host because it displays a similar overall structure and properties. Why GroES is unable to fold the T4 capsid protein in conjunction with GroEL is unknown. Here we show that gp23 binds to the GroEL heptameric ring opposite to the ring that is bound by gp31 (the so-called trans-ring), while no binding to the trans-ring of the GroEL-GroES complex is observed. Although gp23 can be enclosed within the folding cage of the GroEL-gp31 complex, encapsulation within the GroEL-GroES complex is not possible. So it appears that folding of the T4 major capsid protein requires a gp31-dependent cis-folding mechanism likely inside an enlarged “Anfinsen cage” provided by GroEL and gp31.
The smallest hyperbolic 6-manifolds
Authors: Everitt Brent , Ratcliffe John , Tschantz Steven
Published: May 2005

By gluing together copies of an all right-angled Coxeter polytope a number of open hyperbolic

6
6

-manifolds with Euler characteristic

−
1

-1

are constructed. They are the first known examples of hyperbolic

6
6

-manifolds having the smallest possible volume.
Finding the Words to Say It: The Healing Power of Poetry
Authors: Carroll Robert
Published: May 2005

My purpose in this paper is to help you experience for yourself the potential of poetry to heal by feeling its power through your own voice. Many people have an intuitive sense that voice in general and poetry in particular can be healing. We have all experienced the comfort of soothing words. Finding the words to articulate a traumatic experience can bring relief. A letter between friends who are fighting can heal a relational wound. People are frequently moved to write a poem in times of extremity. In mainstream culture there are subjects that are not talked about. They are taboo. For example, each of us is going to die, but we do not talk about dying. We are all in the dialogue of illness, death and dying, whether or not we are talking about it. Poetry gives us ways to talk about it. Multiple ways of utilizing poetry for healing, growth and transformation will be presented including the Poetry and Brain Cancer project at UCLA. Particular attention will be given to issues of Palliative care. The reader will be directed to the scientific evidence of the efficacy of utilizing expressive writing. The developing professional field of Poetry Therapy, and The National Association for Poetry Therapy will be discussed.
Effect of 6-thioguanine on the stability of duplex DNA
Authors: Bohon Jen , de los Santos Carlos R.
Published: May 2005

The incorporation of 6-thioguanine (S6G) into DNA is a prerequisite for its cytotoxic action, but duplex structure is not significantly perturbed by the presence of the lesion [J. Bohon and C. R. de los Santos (2003) Nucleic Acids Res ., 31, 1331–1338]. It is therefore possible that the mechanism of cytotoxicity relies on a loss of stability rather than a pathway involving direct structural recognition. The research described here focuses on the changes in thermodynamic properties of duplex DNA owing to the introduction of S6G as well as the kinetic properties of base pairs involving S6G. Replacement of a guanine in a G•C pair by S6G results in ∼1 kcal/mol less favorable Gibbs free energy of duplex formation at 37°C. S6G•T and G•T mismatch-containing duplexes have almost identical Gibbs free energy at 37°C, with values ∼3 kcal/mol less favorable than that of the control. Base pair stability is affected by S6G. The lifetime of the normal G•C base pair is ∼125 ms, whereas that of the G•T mismatch is below the detection limit. The lifetimes of S6G•C and S6G•T pairs are ∼7 and 2 ms, respectively, demonstrating that, although S6G significantly decreases the stability of the pairing with cytosine, it slightly increases that of a mismatch.
Mapping of transcription start sites in
Saccharomyces cerevisiae
using 5′ SAGE
Authors: Zhang Zhihong , Dietrich Fred S.
Published: May 2005

A minimally addressed area in Saccharomyces cerevisiae research is the mapping of transcription start sites (TSS). Mapping of TSS in S.cerevisiae has the potential to contribute to our understanding of gene regulation, transcription, mRNA stability and aspects of RNA biology. Here, we use 5′ SAGE to map 5′ TSS in S.cerevisiae . Tags identifying the first 15–17 bases of the transcripts are created, ligated to form ditags, amplified, concatemerized and ligated into a vector to create a library. Each clone sequenced from this library identifies 10–20 TSS. We have identified 13 746 unique, unambiguous sequence tags from 2231 S.cerevisiae genes. TSS identified in this study are consistent with published results, with primer extension results described here, and are consistent with expectations based on previous work on transcription initiation. We have aligned the sequence flanking 4637 TSS to identify the consensus sequence A(A rich ) 5 NPy A (A/T)NN(A rich ) 6 , which confirms and expands the previous reported Py A (A/T)Pu consensus pattern. The TSS data allowed the identification of a previously unrecognized gene, uncovered errors in previous annotation, and identified potential regulatory RNAs and upstream open reading frames in 5′-untranslated region.
HP1 modulates the transcription of cell-cycle regulators in
Drosophila melanogaster
Authors: De Lucia Filomena , Ni Jian-Quan , Vaillant Catherine , Sun Fang-Lin
Published: May 2005

Heterochromatin protein 1 (HP1) was originally described as a non-histone chromosomal protein and is required for transcriptional gene silencing and the formation of heterochromatin. Although it is localized primarily at pericentric heterochromatin, a scattered distribution over a large number of euchromatic loci is also evident. Here, we provide evidence that Drosophila HP1 is essential for the maintenance of active transcription of euchromatic genes functionally involved in cell-cycle progression, including those required for DNA replication and mitosis. Depletion of HP1 in proliferating embryonic cells caused aberrant progression of the cell cycle at S phase and G2/M phase, linked to aberrant chromosome segregation, cytokinesis, and an increase in apoptosis. The chromosomal distribution of Aurora B, and the level of phosphorylation of histone H3 serine 10 were also altered in the absence of HP1. Using chromatin immunoprecipitation analysis, we further demonstrate that the promoters of a number of cell-cycle regulator genes are bound to HP1, supporting a direct role for HP1 in their active transcription. Overall, our data suggest that HP1 is essential for the maintenance of cell-cycle progression and the transcription of cell-cycle regulatory genes. The results also support the view that HP1 is a positive regulator of transcription in euchromatin.
Trilobite spines and beetle horns: sexual selection in the Palaeozoic?
Authors: Knell Robert J , Fortey Richard A
Published: May 2005

Raphiophorid trilobites commonly bore median cephalic protuberances such as spines or bulbs, showing a remarkable variety of form. It is unlikely that their primary function was for protection or in hydrodynamics. A case is made that they were secondary sexual features, by comparison with similar morphological structures developed on rhinoceros beetles and other arthropods. This interpretation is supported by four lines of evidence: their ontogeny, their diversity, the existence of plausible examples of sexual dimorphs in some cases and the fact that they show positive allometry.
A scaling analysis of Sal'nikov's reaction, P→A→B, in the presence of natural convection and the diffusion of heat and matter
Authors: Campbell A.N , Cardoso S.S.S , Hayhurst A.N
Published: May 2005

Sal'nikov's chemical reaction is very simple; it consists of two consecutive first-order steps, producing a product B from a precursor P via an active intermediate A, in P→A→B. The first step is assumed to be thermoneutral, with zero activation energy, while the second step is exothermic and has a positive activation energy. These properties make this mechanism one of the simplest to display thermokinetic oscillations, as seen in cool flames. We consider a pure gas, P, undergoing Sal'nikov's reaction in a closed spherical vessel, whose walls are held at a constant temperature. Natural convection becomes significant once the temperature is high enough for the Rayleigh number to reach approximately 103. The subsequent behaviour of the system depends on the interaction between convection, diffusion of heat and mass, and chemical kinetics. By examining the governing equations, we develop and evaluate scales for the characteristic velocity, concentration of the intermediate A and the temperature rise during the progress of the reaction. These scales depend on the characteristic time-scales for the interacting phenomena of chemical reaction, diffusion and natural convection. Our theoretical predictions are verified by full numerical simulation for the two limiting cases when transport is dominated, respectively, by diffusion and natural convection.
Low genetic diversity in a marine nature reserve: re-evaluating diversity criteria in reserve design
Authors: Bell J.J , Okamura B
Published: May 2005

Little consideration has been given to the genetic composition of populations associated with marine reserves, as reserve designation is generally to protect specific species, communities or habitats. Nevertheless, it is important to conserve genetic diversity since it provides the raw material for the maintenance of species diversity over longer, evolutionary time-scales and may also confer the basis for adaptation to environmental change. Many current marine reserves are small in size and isolated to some degree (e.g. sea loughs and offshore islands). While such features enable easier management, they may have important implications for the genetic structure of protected populations, the ability of populations to recover from local catastrophes and the potential for marine reserves to act as sources of propagules for surrounding areas. Here, we present a case study demonstrating genetic differentiation, isolation, inbreeding and reduced genetic diversity in populations of the dogwhelk
Nucella lapillus
in Lough Hyne Marine Nature Reserve (an isolated sea lough in southern Ireland), compared with populations on the local adjacent open coast and populations in England, Wales and France. Our study demonstrates that this sea lough is isolated from open coast populations, and highlights that there may be long-term genetic consequences of selecting reserves on the basis of isolation and ease of protection.
Male‐biased size dimorphism in ichneumonine wasps (Hymenoptera: Ichneumonidae) – the role of sexual selection for large male size
Authors: Teder Tiit
Published: May 2005

Abstract.  1. Sexual differences in body size are expected to evolve when selection on female and male sizes favours different optima.

2. Insects have typically female‐biased size dimorphism that is usually explained by the strong fecundity advantage of larger size in females. However, numerous exceptions to this general pattern have led to the search for selective pressures favouring larger size in males.

3. In this study, the benefits of large size were investigated in males of four species of ichneumonine wasps, a species‐rich group of parasitoids, many representatives of which exhibit male‐biased size dimorphism.

4. Mating behaviour of all ichneumonine wasps are characterised by pre‐copulatory struggles, in the course of which males attempt to override female reluctance to mate. A series of laboratory trials was conducted to study the determinants of male mating success.

5. A tendency was found for larger males as well as those in better condition to be more successful in achieving copulations. Size dimorphism of the species studied, mostly male‐biased in hind tibia length but female‐biased in body weight, indicates that sexual selection in males favours longer bodies and appendages rather than larger weight.

6. The qualitative similarity of the mating patterns suggests that sexual selection cannot completely explain the considerable among‐species differences in sexual size dimorphism.

7. The present study cautions against using various size indices as equivalents for calculating sexual size dimorphism.

8. It is suggested that female reluctance in ichneumonine wasps functions as a mechanism of female mate assessment.
Genetics of essential hypertension
Authors: Coy Virginia
Published: May 2005

Purpose

To inform healthcare providers of the genetics involved in the development of essential hypertension and to illustrate the role the healthcare provider has in the management of patients with essential hypertension.

Data sources

Research‐based articles in the medical literature, selected published literature in refereed journals, and Internet sites.

Conclusions

Essential hypertension is a complex chronic disease that affects many people and has grave implications for the patient. Genetics involved in the development of essential hypertension and treatment choices is evolving; therefore, the healthcare provider must be knowledgeable in these areas to effectively care for patients with hypertension.

Implications for practice

Essential hypertension is a chronic disease that affects over 50 million people in the United States. Advances in genetics are allowing scientists to discover the genetic basis of hypertension. With knowledge of genetics and environmental factors involved in the development of essential hypertension, healthcare providers will be able to more effectively screen, manage, and treat individuals with hypertension.
Diet choice of large carnivores in northern Cameroon
Authors: Breuer Thomas
Published: May 2005

The diet of African wild dogs, lions and spotted hyenas was studied in the woodland savannah of Faro National Park and surrounding hunting zones in northern Cameroon during the dry season. Faecal analysis revealed that the diet of the three large carnivores overlaps considerably. Frequencies of prey remains of large and medium‐sized antelopes were highest, with Buffon's kob being by far the most common prey species. Carnivores seem to consume most abundant prey species. No prey item of domestic livestock was found in the faeces. Faecal analysis has proved to be a useful method to reveal diet choice for large carnivores in northern Cameroon. Detailed information on the distribution and density of large carnivores and their prey is needed to give a better picture of the status of carnivores in northern Cameroon and to help resolve conflicts with livestock. Further investigations into the seasonal variation of predation and other factors structuring the large carnivore community in northern Cameroon are recommended.
Effects of selective logging (50 years ago) on habitat use and ranging behaviour of a forest understorey bird (red‐tailed bristlebill, Bleda syndactyla) in Uganda
Authors: Dale Svein , Slembe Bjørnar
Published: May 2005

To understand the effects of selective logging on animals we compared habitat use and ranging behaviour of a common understorey passerine bird, the red‐tailed bristlebill (Bleda syndactyla), in logged and unlogged forest in the Budongo Forest Reserve, Uganda. The secondary forest had been selectively logged about 50 years ago, and differed in vegetation structure from the unlogged, primary forest in particular by having a denser understorey. Home range size of radio‐tagged bristlebills was 10–20% larger (depending on data sample used) in unlogged forest compared with logged forest, but the difference was not significant. Movement rates during 1‐h observation periods were highest in unlogged forest. The bristlebill has been characterized as a bird of dense understorey vegetation, and data from unlogged forest in the present study suggested that areas with dense understorey were used more often than expected. In logged forest, no habitat preferences were found, probably because the forest had a dense understorey throughout. Assuming that smaller home ranges and lower movement rates indicate better habitat, there was no evidence that bristlebills were negatively affected by logging. The preference for dense understorey in unlogged forest suggests that the bristlebill may benefit from selective logging because this leads to an increase in dense understorey.
Big is not better: small Acacia mellifera shrubs are more vital after fire
Authors: Meyer Katrin M. , Ward David , Moustakas Aristides , Wiegand Kerstin
Published: May 2005

Fire and acacias are vital components in savanna dynamics but little is known about the relationship between postfire mortality and size of Acacia species. We determined mortality, height, and height of resprouts of the encroaching shrub species Acacia mellifera in a semi‐arid South African savanna 2 years after fire. As expected, resprouting ability after topkill was high, only 9% of the studied shrubs died completely. Surprisingly, shrubs that died in the fire were significantly taller than their resprouting conspecifics. Results from quantile regression show that the height of regrowth relative to the total height of taller shrubs is less than in smaller shrubs, despite taller shrubs having more access to below‐ground resources. We offer two possible explanations for these unexpected results: in taller shrubs, the maximum longitudinal growth rate of resprouts may be reached and therefore, resources may be invested in a greater number of resprouts or stored as reserves. Alternatively, resprouting ability may be impaired in old age by a senescence effect caused by the accumulation of physiological dysfunctions.
Comparison between antithymocyte globulin and alemtuzumab and the possible impact of KIR‐ligand mismatch after dose‐reduced conditioning and unrelated stem cell transplantation in patients with multiple myeloma
Authors: Kröger Nicolaus , Shaw Bronwen , Iacobelli Simona , Zabelina Tatjana , Peggs Karl , Shimoni Avichai , Nagler Arnon , Binder Thomas , Eiermann Thomas , Madrigal Alejandro , Schwerdtfeger Rainer , Kiehl Michael , Sayer Herbert Gottfried , Beyer Jörg , Bornhäuser Martin , Ayuk Francis , Zander Axel Rolf , Marks David I. ,   the Clinical Trial Committee of the British Society of Blood and Marrow Transplantation and the German Cooperative Transplant Group
Published: May 2005

We compared antithymocyte globulin (ATG) with alemtuzumab in 73 patients with multiple myeloma, who underwent reduced conditioning with melphalan/fludarabine, followed by allogeneic stem cell transplantation from human leucocyte antigen‐matched or ‐mismatched unrelated donors. The ATG group had more prior high‐dose chemotherapies (P < 0·001), while bone marrow was used more as the stem cell source in the alemtuzumab group (P < 0·001). Alemtuzumab resulted in faster engraftment of leucocytes (P = 0·03) and platelets (P = 0·02) and in a lower incidence of acute graft versus host disease (GvHD) grades II–IV (24% vs. 47%, P = 0·06). More cytomegalovirus (CMV) seropositive patients in the alemtuzumab group experienced CMV reactivation (100% vs. 47%, P = 0·001). The cumulative incidence of treatment‐related mortality at 2 years was 26% [95% confidence interval (CI) = 12–37%] for ATG vs. 28% (95% CI = 15–55%) for alemtuzumab, P = 0·7. There was no significant difference in the estimated 2‐year overall and progression‐free survival between ATG and alemtuzumab: 54% (95% CI: 39–75%) vs. 45% (95% CI: 28–73%) and 30% (95% CI: 16–55%) vs. 36% (95% CI: 20–62%) respectively. In multivariate analysis, treatment with alemtuzumab had a higher risk for relapse (hazard ratio: 2·37; P = 0·05) while killer immunoglobulin‐like receptor (KIR)‐ligand mismatch was protective for relapse (P < 0·0001). We conclude that alemtuzumab produced less acute GvHD, but higher probability of relapse. The data implicated a major role of KIR‐ligand mismatched transplantation in multiple myeloma.
Resistance of potato cultivars to Synchytrium endobioticum in field and laboratory tests, risk of secondary infection, and implications for phytosanitary regulations
Authors: Baayen R. P. , Bonthuis H. , Withagen J. C. M. , Wander J. G. N. , Lamers J. L. , Meffert J. P. , Cochius G. , Van Leeuwen G. C. M. , Hendriks H. , Heerink B. G. J. , Van Den Boogert P. H. J. F. , Van De Griend P. , Bosch R. A.
Published: May 2005

Laboratory (Spieckermann) tests, pot tests and field tests provided concordant evidence for the partial nature of resistance of potatoes to pathotypes 1 (D1) and 6 (O1) of Synchytrium endobioticum. Susceptible potato cultivars produced large warts (> 16 mm in diameter) in Spieckermann tests and had low field resistance levels (1–6). Field‐resistant cultivars (levels 7–9) produced small warts or no warts at all in Spieckermann and field tests. In pot tests, at low inoculum levels (1 sporangium per 25 g soil) susceptible cultivars still developed warts, whereas field‐resistant ones did not develop any warts below 25 sporangia per g soil. Above 35 sporangia per g soil, 100% disease incidence was observed in susceptible cultivars but only minimal wart development in field‐resistant ones. Tests with continuous cultivation of potato cultivars in infected soil during three consecutive years showed that field‐resistant cultivars will not support build‐up of inoculum in soil. It is concluded that field‐resistant cultivars do not create a risk of secondary infection, the criterion given for resistance in EU Directive 69/464/EC.
Detection of Meloidogyne incognita and Pochonia chlamydosporia by fluorogenic molecular probes*
Authors: Ciancio A. , Loffredo A. , Paradies F. , Turturo C. , Sialer M. Finetti
Published: May 2005

Fluorescent molecular probes were applied for detection of the plant parasitic nematode Meloidogyne incognita and the nematode‐egg parasitic fungus Pochonia chlamydosporia var. chlamydosporia. A region in the M. incognita rDNA including ITS2 was selected for amplification and recognition with a real‐time PCR assay, based on a combination of three specific motifs, each recognized by a specific fluorescent probe. Similarly, a Scorpion probe was designed for the RT‐PCR quantification of P. c. chlamydosporia. For this purpose, the ITS‐2 rDNA gene of the fungus was sequenced from a number of Italian isolates. A conserved region unique for P. c. chlamydosporia found in the ITS‐2 rDNA gene was used. The probes allowed recognition of single juveniles of M. incognita and of the mycelium‐ or soil‐extracted fungal DNA. The potentialities of the detection procedures are discussed.
Real‐time PCR assay for the identification of Thrips palmi*
Authors: Kox L. F. F. , Van Den Beld H. E. , Zijlstra C. , Vierbergen G.
Published: May 2005

Since Thrips palmi became a regulated pest for most European countries, inspections at points of entry into Europe and monitoring in Europe have intensified not only for T. palmi but also for thrips as a whole. Morphological identification of thrips is performed on adults and to a lesser extent on second‐stage larvae only, because no adequate identification keys for the separation of species based on the characteristics of eggs, first‐stage larvae, pre‐pupae or pupae are available. We have developed a real‐time PCR assay based on TaqMan. A T. palmi‐specific set of primers and probe were selected within the mitochondrial cytochrome oxidase I (COI) gene. The specificity of the assay was assessed using 15 specimens of Thrips palmi and 61 specimens of 23 other thrips species commonly occuring in Europe. All T. palmi specimens were detected, and no cross reactions with other thrips were observed. The method was tested on single larvae and adults and proved to be applicable for both those stages of T. palmi.
Application of real‐time RT‐PCR for large‐scale testing of potato for Potato spindle tuber pospiviroid*
Authors: Roenhorst J. W. , Jansen C. C. C. , Kox L. F. F. , De Haan E. G. , Van Den Bovenkamp G. W. , Boonham N. , Fisher T. , Mumford R. A.
Published: May 2005

The real‐time RT‐PCR protocol of Boonham and coworkers performed extremely well in a recent ring test, comparing different methods for detection of Potato spindle tuber pospiviroid (PSTVd) in several laboratories. Since, in addition, real‐time PCR technology has proved suitable for high‐throughput testing, this method was chosen as the starting point for the development of a protocol for the large‐scale testing of potato. The initial experiments focused on the specificity of the primers and probes with regard to different isolates of PSTVd and other (pospi‐) viroids. Further experiments were performed with leaf material from both primarily and secondarily infected plants. The parameters studied were sampling position, growing‐on temperature and bulking rate. In addition, different grinding, nucleic‐acid extraction and disinfection methods were compared. To monitor false negatives and positives, different controls were included and tested in duplex and triplex formats. The final protocol was tested using a hundred samples from the Dutch potato‐monitoring programme. The results of this pilot experiment were promising. Future plans include the development of a protocol for direct tuber testing and inter‐laboratory ring testing of the protocols.