bluuebunny/crossref_metadata_2025 huggingface dataset:
Tripartite climate reversal in Central Europe 5600–5300 years ago
Authors: Magny Michel , Leuzinger Urs , Bortenschlager Sigmar , Haas Jean Nicolas
Published: August 2005

The history of variations in water level of Lake Constance, as reconstructed from sediment and pollen analysis of a sediment sequence from the archaeological site of Arbon-Bleiche 3, shows an abrupt rise in lake level dendrochronologically dated to 5375 yr ago (5320 yr relative to AD 1950). This event, paralleled by the destruction of the Neolithic village by fire, provoked the abandonment of this prehistoric lake-shore location established in the former shallow bay of Arbon-Bleiche, and was the last of a series of three episodes of successively higher lake level, the first occurring at 5600–5500 cal yr B.P. The dendrochronologically dated rise event was synchronous with an abrupt increase in atmospheric14C. This supports the hypothesis of an abrupt climate change forced by varying solar activity. Moreover, the three successive episodes of higher lake level between 5600 and 5300 cal yr B.P. at Arbon-Bleiche 3 coincided with climatic cooling and/or changes in moisture conditions in various regions of both hemispheres. This period corresponds to the mid-Holocene climate transition (onset of the Neoglaciation) and suggests inter-hemispheric linkages for the climate variations recorded at Arbon-Bleiche 3. This mid-Holocene climate reversal may have resulted from complex interactions between changes in orbital forcing, ocean circulation and solar activity. Finally, despite different seasonal hydrological regimes, the similarities between lake-level records from Lake Constance and from Jurassian lakes over the mid-Holocene period point to time scale as a crucial factor in considering the possible impact of climate change on environments.
reproductive health status, knowledge, and access to health care among female migrants in shanghai, china
Authors: feng wang , ren ping , shaokang zhan , anan shen
Published: August 2005

as the largest labour flow in human history, the recent rise in migration in china has opened up unprecedented opportunities for millions of chinese to rearrange their lives. at the same time, this process has also posed great challenges to chinese migrants, especially female migrants, who not only face a bias against ‘outsiders’ but also have a greater need for reproductive health-related services in their migratory destinations. based on data collected via multiple sources in shanghai, china’s largest metropolis, this study profiles the changing characteristics of female migrants, presents data on self-reported symptoms of reproductive health-related problems and knowledge on reproductive health issues, compares maternal and child health measures between migrants and local residents, and examines factors related to reproductive health knowledge and migrants’ access to health care in urban china. results of this study show a relatively low level of self-reported reproductive health problems among female migrants, coupled with a relatively high level of ignorance in knowledge related to std. both self-reported health status and knowledge of reproductive health are related to migrants’ educational attainment and length of stay in the urban destination. this study also finds ample evidence that female migrants’ access to urban health care is limited by a number of institutional barriers.
biological and psychosocial determinants of male and female human sexual orientation
Authors: james william h.
Published: August 2005

some propositions on male and female sexual orientation will be considered. some of these are established; others are more speculative. the aim is to offer some notes towards a coherent, comprehensive theory of sexual orientation. 1. the distinction between butch and femme lesbians seems real rather than a social construct. 2. high levels of prenatal steroid hormones seem to be causally associated with the sexual orientation of butch lesbians. however it is not established whether the causal process operates prenatally or postnatally (or both). this is so because prenatal hormone levels are thought to correlate positively with postnatal hormone levels. and high postnatal hormone levels may facilitate homosexual behaviour as a consequence of sensation-seeking. 3. male bisexuals also are interpreted to have been exposed to high prenatal testosterone levels. but (for reasons similar to those outlined above in regard to butch lesbians) it is unclear whether these have a direct prenatal effect on the brain or whether they are precursors of high postnatal testosterone levels, which are associated with male bisexual orientation by promoting sensation-seeking behaviour. 4. postnatal learning processes seem to be causally involved in the sexual orientation of some femme lesbians and some exclusive male homosexuals. 5. some homosexual men have genes that predispose to their sexual orientation. 6. the same may apply to some lesbians, but such genes have not, as far as i know, been identified. 7. people (of both sexes) who engage in same-sex sexual behaviour may be classified simultaneously in two ways, viz (1) ‘active’ vs ‘passive’ and (2) those who do and those who do not engage (or consider engaging) in sex with members of the opposite sex. ex hypothesi, some of the ‘active’ ones initiate some of the ‘passive’ ones. the active ones are driven more by hormones and the passive ones by psychosocial factors. the active males contain a substantial proportion of self-identified bisexuals; and the active females a substantial proportion of self-identified butches. 8. these two active categories (butch lesbians and male bisexuals) share a number of endocrinological, psychological, morphological and behavioural features vis-à-vis their exclusively homosexual and heterosexual peers. methods of testing some of these ideas are presented.
sexual risk behaviour among the youth in the era of hiv/aids in south africa
Authors: zambuko oliver , mturi akim j.
Published: August 2005

the paper discusses factors associated with sexual risk behaviour, i.e. failure to use condoms consistently during sexual intercourse, among unmarried sexually experienced youths in south africa. data from the ‘transitions to adulthood in the context of aids in south africa’ surveys of 1999 and 2001 were analysed to identify factors associated with high sexual risk behaviour among the youth. the multinomial regression models for male and female youths were fitted separately for the 1999 and 2001 data sets. the results show increasingly consistent use of condoms during sexual intercourse and that high sexual risk behaviour among youths is predominantly determined by social factors such as ‘ever-pregnant’ or ‘ever made pregnant’, ‘ever given something for sex’, age of sexual partner, currently in school, pressured by friends to have sex, peer influence on safe sex and education level for males. there is evidence that availability of contraception information is important in strategic interventions that seek to change the sexual behaviour of the youth in south africa.
analysing the relationship between family planning workers’ contact and contraceptive switching in rural bangladesh using multilevel modelling
Authors: hossain mian b.
Published: August 2005

with a population of over 131 million and a fertility rate of 29·9 per 1000, population growth constitutes a primary threat to continued economic growth and development in bangladesh. one strategy that has been used to cease further increases in fertility in bangladesh involves using family planning outreach workers who travel throughout rural and urban areas educating women regarding contraceptive alternatives. this study uses a longitudinal database to assess the impact of family planning outreach workers’ contact upon contraceptive switching and upon the risk of an unintended pregnancy. using longitudinal data on contraceptive use from the operations research project (orp) of the international centre for diarrhoeal disease research (icddr,b) in bangladesh, multiple decrement life table analysis and multilevel, discrete-time competing risk hazards models were used to estimate the cumulative probabilities of switching to an alternative form of contraceptive use after a woman engaged in a discussion with an outreach worker. after controlling for the effects of socio-demographic and economic characteristics, the analysis revealed that family planning outreach workers’ contact with women significantly decreases the risk of transitioning to the non-use of contraceptives. this contact also reduces the risk of an unintended pregnancy. family planning workers’ contact with women is associated with the increased risk of a woman switching from one modern method to another modern method. the study results indicate that side-effects and other method-related reasons are the two primary reasons for contraceptive discontinuation in rural bangladesh.
Polyphenol interaction with the T47D human breast cancer cell line
Authors: Nifli Artemissia-Phoebe , Kampa Marilena , Alexaki Vassilia-Ismini , Notas George , Castanas Elias
Published: August 2005

Experimental and epidemiological studies indicate that antioxidant food polyphenols could have antimitotic activities, interfering with cancer initiation, progression or mortality. Circulating polyphenols are far lower than the nominal value in foods. In the rare studies dealing with polyphenol bioavailability, it was noted that their active concentrations in the blood are <1% of their food concentration. In the present study we investigated the effect of four polyphenols (resveratrol, and the flavonoids quercetin, catechin and epicatechin, major constituents of wine) in the hormone-sensitive human cancer cell line T47D, at concentrations compatible with their calculated plasma concentrations after ingestion of a moderate quantity of wine (nM or pM). Our results indicate that cell growth was decreased, with cells being arrested at the S phase of the cycle. In addition, we provide evidence of a bimodal modulation of the NO/NOS system, affecting its activity and transcription. We show that modulation of this system is sufficient to explain polyphenol action on this cell line. This result suggests a potential importance of wine ingestion and possibly the consumption of other polyphenol-rich dietary foods and drinks in the control of breast cancer cell growth.
Functional study of the equine β-casein and κ-casein gene promoters
Authors: Lenasi Tina , Kokalj-Vokac Nadja , Narat Mojca , Baldi Antonella , Dovc Peter
Published: August 2005

Casein genes are expressed in a tissue-specific and highly coordinated manner. The main goals of casein gene promoter studies are to unravel cis- and trans-acting factors involved in the complex signalling pathway controlling milk production, and to explore the possibility of using these promoters for tissue-specific production of heterologous proteins in the mammary gland. Here we present a comparative study of the equine β-casein and κ-casein gene proximal promoters. In order to confirm the assumption that in the horse, as in other mammalian species, casein genes are organized in a cluster located on a single chromosome, we performed in situ hybridization of pro-metaphase chromosomes with two BAC clones containing different equine casein genes. Sequence analysis of the β-casein and κ-casein gene proximal promoters revealed binding sites for activators (STAT5, GRE, NF1, MAF) and repressors (YY1, PMF), characteristic for casein genes. The alignments of casein gene promoters revealed the highest sequence identity in the proximal promoter region between the equine and human β-casein gene promoters. We directly compared the activity of equine β-casein and κ-casein gene promoters in vitro using bovine mammary gland cell line BME-UV1. In this system, the κ-casein gene proximal promoter activated the reporter gene expression more efficiently than the β-casein gene promoter of approximately the same length. The 810 bp of β-casein promoter activated the reporter gene expression more efficiently than the long fragment (1920 bp) and the 1206 bp fragment of the same promoter, which included also 396 bp of 5′ UTR.
Trypanosomes, fleas and field voles: ecological dynamics of a host-vector–parasite interaction
Authors: SMITH A. , TELFER S. , BURTHE S. , BENNETT M. , BEGON M.
Published: August 2005

To investigate the prevalence of a flea-borne protozoan (Trypanosoma (Herpetosoma) microti) in its field vole (Microtus agrestis) host, we monitored over a 2-year period a range of intrinsic and extrinsic parameters pertaining to host demographics, infection status and vector (flea) prevalence. Generalized Linear Mixed Modelling was used to analyse patterns of both flea and trypanosome occurrence. Overall, males of all sizes and ages were more likely to be infested with fleas than their female counterparts. Flea prevalence also showed direct density dependence during the winter, but patterns of density dependence varied amongst body mass (age) classes during the summer. Trypanosome prevalence did not vary between the sexes but was positively related to past flea prevalence with a lag of 3 months, with the highest levels occurring during the autumn season. A convex age-prevalence distribution was observed, suggesting that individuals develop a degree of immunity to trypanosome infection with age and exposure. An interaction between age and whether the individual was new or recaptured suggested that infected animals are less likely to become territory holders than their uninfected counterparts.
Differential polyadenylation of ribosomal RNA during post-transcriptional processing inLeishmania
Authors: DECUYPERE S. , VANDESOMPELE J. , YARDLEY V. , DE DONCKER S. , LAURENT T. , RIJAL S. , LLANOS-CUENTAS A. , CHAPPUIS F. , AREVALO J. , DUJARDIN J.-C.
Published: August 2005

The protozoan parasiteLeishmaniabelongs to the most ancient eukaryotic lineages and this is reflected in several distinctive biological features, such as eukaryotic polycistronic transcription and RNA trans-splicing. The disclosure of this organism's unusual characteristics leads to a better understanding of the origin and nature of fundamental biological processes in eukaryotes. Here we report another unusual phenomenon as we demonstrate that precursor ribosomal RNA can be extensively polyadenylated during post-transcriptional processing[dagger]. Furthermore, we demonstrate that the degree of precursor rRNA polyadenylation is variable in different strains and in the different life-stages of a strain.
Ocular toxoplasmosis in mice: comparison of two routes of infection
Authors: TEDESCO R. C. , SMITH R. L. , CORTE-REAL S. , CALABRESE K. S.
Published: August 2005

This paper aims to test the influence of route of infection (intravitreal and instillation) on the course of ocular toxoplasmosis in mice, using the Toxoplasma gondii Me-49 strain. All mice inoculated intravitreally or by instillation presented the same pattern of infection. Using either route, parasites were observed in the retinal vessel with the formation of a glial reaction in the inner plexiforme layer and discontinuity of the pigmented epithelium of the retina 7 days after infection. However, when the intravitreal route was used a more intense inflammatory infiltrate was observed in the retina. The results suggest that inoculation route remarkably influences the inflammatory pattern in ocular toxoplasmosis and that the instillation route should be preferentially used in experimental infections in the murine ocular model of infection by T. gondii, specially with small animals where there is extensive needle damage, which is not observed in the instillation route.
Purification and characterization of a metacestode cysteine proteinase fromTaenia soliuminvolved in the breakdown of human IgG
Authors: BAIG S. , DAMIAN R. T. , MOLINARI J. L. , TATO P. , MORALES-MONTOR J. , WELCH M. , TALHOUK J. , HASHMEY R. , WHITE A. C.
Published: August 2005

Infection of the central nervous system byTaenia soliumcysticerci is the cause of human neurocysticercosis, a major neurological infection in the Third World and an emerging infectious disease in the United States. We previously isolated a cysteine proteinase from cysticerci ofTaenia crassicepsand demonstrated that it degrades human IgGin vitro. We have now isolated a 48 kDa thiol-dependent proteinase fromT. solium. TheT. soliumenzyme also degrades human IgG, but does not significantly degrade albumin. IgG degradation was inhibited by cysteine proteinase inhibitors, but not significantly by inhibitors of aspartic, serine, or metalloproteinases. The peptide substrate specificity and pH optimum resemble cathepsin L. The Km for the peptide substrate Z-Phe-Arg-AFC was calculated to be 7·0×10−6M, the Kcat was 1·98×105s−1, and the Kcat/Km 2·84×109M−1s−1, a value which is within the diffusion control limit for highly catalytic enzymes. We propose that immunoglobulin degradation by theT. soliumcysteine proteinase may play a key role in the host-parasite interface and could be employed as a target for chemotherapy.
Nematology: Advances and Perspectives, Vol. 1, Nematode Morphology, Physiology and Ecology. By Z. X. Chen, S. Y. Chen and D. W. Dickson, pp. 656. International CABI Publishing, UK, 2004. ISBN 0 85199 645. £85.00 (US$150.00).
Authors: BEHNKE JERZY M.
Published: August 2005

As a zoologist, I have never really understood why those of us who study nematodes continue to partition ourselves into at least two distinct camps, one of which works on the plant-parasitic and free-living species, and the other primarily on animal-parasitic species. And I suspect that nematodes themselves are equally puzzled by this segregation of their ardent scholars. Historically, of course, plant nematologists aggregated in crop research and botany departments, whereas the animal nematologists were stationed in livestock, veterinary, medical and zoological departments of research institutes and universities. I found much of interest in NematologyVol. 1, but I was left with the impression that, whilst the ‘iron curtain’ was beginning to tumble, it still had a long way to fall. We have not yet reached a stage where nematodes as distinct organisms, whatever their niche, take priority in our thinking. But I race ahead. Let us retrace and begin with the details of this volume.
A NEW SPECIES OF ONOSMA (BORAGINACEAE–LITHOSPERMEAE) FROM SOUTHERN TURKEY
Authors: RIEDL H. , BINZET R. , ORCAN N.
Published: August 2005

A new species of Onosma (Boraginaceae), O. mersinana, in sect. Asterotricha, is described from southern Turkey, and its affinities discussed.
OLD WORLD GESNERIACEAE VII: CYRTANDRA SCHIZOSTYLA, C. VELUTINA AND THEIR RESPECTIVE ALLIES IN BORNEO
Authors: HILLIARD O. M. , BURTT B. L.
Published: August 2005

Two groups of species are dealt with: first, Cyrtandra schizostyla together with three new species, all notable for the extraordinary elaboration of their anthers; second, C. velutina and C. diplotricha together with four new species, notable for their remarkably slender, soft-walled fruits. All species are fully described and identification keys provided.
OLD WORLD GESNERIACEAE VIII: MISCELLANEOUS BORNEAN SPECIES OF CYRTANDRA
Authors: BURTT B. L.
Published: August 2005

Six new species of Cyrtandra from Borneo (C. apaensis, C. burleyana, C. filisecta, C. subsphaerocarpa, C. tibangensis, C. toreniiflora) are described. Cyrtandra albibracteata is re-described in order to correct gross errors in the original paper. The published diagnosis validating C. paragibbsiae from Brunei is supplemented by a full description.
TWO NEW SPECIES OF BORAGINACEAE (TRIBE CYNOGLOSSEAE) FROM TURKEY
Authors: AYTAÇ Z. , MILL R. R.
Published: August 2005

Two new species of Boraginaceae are described from Turkey: Paracaryum hedgei and Rindera dumanii. Their affinities and phytogeography are discussed. Both species are illustrated and their distributions mapped. Rindera sect. Bilegnum is raised to subgeneric rank as Rindera subgen. Bilegnum.
TAXONOMIC AND NOMENCLATURAL NOTES ON PHILIPPINE FERNS II: THREE NEW NAMES IN ASPLENIUM
Authors: SALGADO E.
Published: August 2005

The new names Asplenium luzonicum and A. perplexum are published to replace the homonyms A. cristatum Brack. and A. riparium Brack.; their nomenclatural history is reviewed and data are provided to support their retention as separate species. The legitimate name A. baileyanum should be used instead of the homonym A. gracile Fée.
Folded continental and oceanic nappes on the southern side of Monte Rosa (western Alps, Italy): Anatomy of a double collision suture
Authors: Pleuger Jan , Froitzheim Nikolaus , Jansen Ekkehard
Published: August 2005

Previous work suggested a double collision suture, including ophiolites from two oceanic basins (Valais and Piemont‐Liguria), on the southern side of Monte Rosa (Penninic Alps, northern Italy). This area was studied using field mapping, microstructural analysis, and neutron texture goniometry. After its formation and eclogite‐facies metamorphism of continental and oceanic units, the suture was deformed by four successive folding and shearing events under greenschist‐facies conditions, all of them taking place between 40 and 28 Ma. After fold retrodeformation, the following tectonostratigraphy results, from base to top: Monte Rosa gneiss (European margin), Balma serpentinite/eclogite unit (Cretaceous crust of Valais ocean), Stolemberg gneiss (Iberia‐Briançonnais continent), Zermatt‐Saas and Tsaté ophiolites (Jurassic crust of Piemont‐Ligurian ocean), Sesia nappe (continental fragment off the Adria margin). The preservation of this lithological sequence suggests that deep‐seated deformation during multiple continent collision produces heterogeneous strain and extreme thinning of nappes but their original stacking order can still be reconstructed using kinematic analysis and overprinting criteria. This is due to the ductile nature of the collisional deformation which retains the continuity of tectonic contacts.
Non‐power‐law‐scale properties of rainfall in space and time
Authors: Marani Marco
Published: August 2005

The identification of general relationships linking statistical properties of rainfall aggregated at different temporal and spatial scales possesses clear theoretical and practical relevance. Among other properties it is important to characterize the scale dependence of rainfall variability, which may, for many purposes, be summarized by its variance. This paper presents theoretical results and observational analyses connecting the variance of temporal and spatial rainfall to the scale of observation under an assumption of second‐order stationarity. Previous results regarding the theoretical form of the temporal variance as a function of aggregation are refined and extended to the spatial case. It is shown that the variance of aggregated rainfall exhibits an overall nonscaling form within the range of scales of usual hydrological interest. It is further shown that the theoretically derived form of the variance as a function of scale is incompatible with power law relations usually assumed for the second‐order statistical moment within multiscaling approaches to rainfall modeling. Predictions of the theoretical derivations are validated by use of observations representing a wide variety of resolutions (from 2 s to 1 hour in time and 4 km in space), climates, and measurement instruments. The validation shows a good agreement between observations and the theoretically predicted forms of the variance as a function of aggregation. The proposed theoretical framework thus provides a useful context for rainfall analysis, modeling, and downscaling in space and time and suggests careful reexaminations of usual multiscaling assumptions.
Soil organic carbon dynamics as related to land use history in the northwestern Great Plains
Authors: Tan Zhengxi , Liu Shuguang , Johnston Carol A. , Loveland Thomas R. , Tieszen Larry L. , Liu Jinxun , Kurtz Rachel
Published: August 2005

Strategies for mitigating the global greenhouse effect must account for soil organic carbon (SOC) dynamics at both spatial and temporal scales, which is usually challenging owing to limitations in data and approach. This study was conducted to characterize the SOC dynamics associated with land use change history in the northwestern Great Plains ecoregion. A sampling framework (40 sample blocks of 10 × 10 km2 randomly located in the ecoregion) and the General Ensemble Biogeochemical Modeling System (GEMS) were used to quantify the spatial and temporal variability in the SOC stock from 1972 to 2001. Results indicate that C source and sink areas coexisted within the ecoregion, and the SOC stock in the upper 20‐cm depth increased by 3.93 Mg ha−1 over the 29 years. About 17.5% of the area was evaluated as a C source at 122 kg C ha−1 yr−1. The spatial variability of SOC stock was attributed to the dynamics of both slow and passive fractions, while the temporal variation depended on the slow fraction only. The SOC change at the block scale was positively related to either grassland proportion or negatively related to cropland proportion. We concluded that the slow C pool determined whether soils behaved as sources or sinks of atmospheric CO2, but the strength depended on antecedent SOC contents, land cover type, and land use change history in the ecoregion.
Proton temperatures in the ring current from ENA images and in situ measurements
Authors: Zhang X. X. , Perez J. D. , Chen T. , Wang C. , Brandt P. C. , Mitchell D. G. , Wang Y. L.
Published: August 2005

Ion equatorial flux distributions, inverted from energetic neutral atom (ENA) images in different energy channels obtained by the HENA imager on the IMAGE satellite, are used to deduce the plasma ion temperature in the ring current. During the early period of the recovery phase of the strong storm on 12 August 2000, the deduced ion temperatures of the ring current are consistent with the values inferred from in situ LANL MPA measurements. The ion temperatures show a peak in the post‐midnight/pre‐dawn sector coincident with the peak in the equatorial ion distributions. The temperature, however, is more symmetrical than the ion flux implying that, at least in this part of the energy spectrum, the density variations make the major contribution to pressure gradients.
Energy release model of compaction band propagation
Authors: Rudnicki J. W. , Sternlof K. R.
Published: August 2005

The elastic strain energy released per unit advance of a compaction band in an infinite layer of thickness h is used to identify and assess quantities relevant to propagation of isolated compaction bands observed in outcrop. If the elastic moduli of the band and the surrounding host material are similar and the band is much thinner than the layer, the energy released is simply σ+ξhεp where σ+ is the compressive stress far ahead of the band edge, ξh is the thickness of the band and εp is the uniaxial inelastic compactive strain in the band. Using representative values inferred from field data yields an energy release rate of 40 kJ/m2, which is roughly comparable with compaction energies inferred from axisymmetric compression tests on notched sandstone samples. This suggests that a critical value of the energy release rate may govern propagation, although the particular value is likely to depend on the rock type and details of the compaction process.
Systematically convergent basis sets for transition metals. I. All-electron correlation consistent basis sets for the 3d elements Sc–Zn
Authors: Balabanov Nikolai B. , Peterson Kirk A.
Published: August 2005

Sequences of basis sets that systematically converge towards the complete basis set (CBS) limit have been developed for the first-row transition metal elements Sc–Zn. Two families of basis sets, nonrelativistic and Douglas-Kroll-Hess (-DK) relativistic, are presented that range in quality from triple-ζ to quintuple-ζ. Separate sets are developed for the description of valence (3d4s) electron correlation (cc-pVnZ and cc-pVnZ-DK; n=T,Q, 5) and valence plus outer-core (3s3p3d4s) correlation (cc-pwCVnZ and cc-pwCVnZ-DK; n=T,Q, 5), as well as these sets augmented by additional diffuse functions for the description of negative ions and weak interactions (aug-cc-pVnZ and aug-cc-pVnZ-DK). Extensive benchmark calculations at the coupled cluster level of theory are presented for atomic excitation energies, ionization potentials, and electron affinities, as well as molecular calculations on selected hydrides (TiH, MnH, CuH) and other diatomics (TiF, Cu2). In addition to observing systematic convergence towards the CBS limits, both 3s3p electron correlation and scalar relativity are calculated to strongly impact many of the atomic and molecular properties investigated for these first-row transition metal species.
Structure and stability of binary transition-metal clusters (NbCo)n (n⩽5): A relativistic density-functional study
Authors: Wang Xian , Cao Zexing , Lu Xin , Lin Menghai , Zhang Qianer
Published: August 2005

Equilibrium geometries and electronic properties of binary transition-metal clusters, (NbCo)n (n⩽5), have been investigated by means of the relativistic density-functional approach. The metal-metal bonding and stability aspects of these clusters have been analyzed on the basis of calculations. Present results show that these clusters exhibit rich structural varieties on the potential-energy surfaces. The most stable structures have a compact conformation in relatively high symmetry, in which the Nb atoms prefer to form an inner core and Co atoms are capped to the facets of the core. Such building features in clustering of the Nb/Co system are related to the order of bond strength: Nb–Nb>Nb–Co>Co–Co. As the binary cluster size increases, the Nb–Co bond may become stronger than the Nb–Nb bond in the inner niobium core, which results in a remarkable increment of the Nb–Nb bond length. Amongst these binary transition-metal clusters, the singlet (NbCo)4 in Td symmetry has a striking high stability due to the presence of the spherical aromaticity and electronic shell closure. The size dependence of the bond length and stability of the cluster has been explored.
Multiscale modeling, simulations, and experiments of coating growth on nanofibers. Part II. Deposition
Authors: Buldum A. , Clemons C. B. , Dill L. H. , Kreider K. L. , Young G. W. , Zheng X. , Evans E. A. , Zhang G. , Hariharan S. I.
Published: August 2005

This work is Part II of an integrated experimental/modeling investigation of a procedure to coat nanofibers and core-clad nanostructures with thin-film materials using plasma-enhanced physical vapor deposition. In the experimental effort, electrospun polymer nanofibers are coated with aluminum materials under different operating conditions to observe changes in the coating morphology. This procedure begins with the sputtering of the coating material from a target. Part I [J. Appl. Phys. 98, 044303 (2005)] focused on the sputtering aspect and transport of the sputtered material through the reactor. That reactor level model determines the concentration field of the coating material. This field serves as input into the present species transport and deposition model for the region surrounding an individual nanofiber. The interrelationships among processing factors for the transport and deposition are investigated here from a detailed modeling approach that includes the salient physical and chemical phenomena. Solution strategies that couple continuum and atomistic models are used. At the continuum scale, transport dynamics near the nanofiber are described. At the atomic level, molecular dynamics (MD) simulations are used to study the deposition and sputtering mechanisms at the coating surface. Ion kinetic energies and fluxes are passed from the continuum sheath model to the MD simulations. These simulations calculate sputtering and sticking probabilities that in turn are used to calculate parameters for the continuum transport model. The continuum transport model leads to the definition of an evolution equation for the coating-free surface. This equation is solved using boundary perturbation and level set methods to determine the coating morphology as a function of operating conditions.
A constructive algorithm for the Cartan decomposition of SU(2N)
Authors: Earp Henrique N. Sá , Pachos Jiannis K.
Published: August 2005

We present an explicit numerical method to obtain the Cartan-Khaneja-Glaser decomposition of a general element G∊SU(2N) in terms of its “Cartan” and “non-Cartan” components. This effectively factors G in terms of group elements that belong in SU(2n) with n<N, a procedure that can be iterated down to n=2. We show that every step reduces to solving the zeros of a matrix polynomial, obtained by truncation of the Baker-Campbell-Hausdorff formula, numerically. All computational tasks involved are straightforward and the overall truncation errors are well under control.
Improvement of the atmospheric discharge laser-triggered ability using multiple pulses from a kilohertz KrF laser
Authors: Yamaura Michiteru
Published: August 2005

The potential ability of lasers to control lightning can be improved by using a train of pulses with submillisecond separations. Laser-triggered experiments in a small-scale (10-mm gap) atmospheric discharge facility show that the triggering is dramatically enhanced when a five-pulse train of sub-Joule energy is used instead of a single pulse. This effect increases rapidly as the pulse interval is reduced. It appears that at a submillisecond pulse interval, sufficient positive and negative ions survive in subsequent pulses, thus enabling easy deionization. Hence, significant plasma buildup occurs from one pulse to the next. However, this persistence of ions would appear to imply that the rate of recombination (effectively a charge transfer between ions) is considerably lower than previously believed.
High-power picosecond and femtosecond pulse generation from a two-section mode-locked quantum-dot laser
Authors: Rafailov E. U. , Cataluna M. A. , Sibbett W. , Il’inskaya N. D. , Zadiranov Yu. M. , Zhukov A. E. , Ustinov V. M. , Livshits D. A. , Kovsh A. R. , Ledentsov N. N.
Published: August 2005

We demonstrate mode locking in a two-section quantum-dot laser that produces output powers up to 45 mW at 1260 nm. The pulse duration could be varied from 2 ps to as short as 400 fs at the 21 GHz pulse repetition rate.
Enhancement of electron injection in inverted top-emitting organic light-emitting diodes using an insulating magnesium oxide buffer layer
Authors: Choi Ho Won , Kim Soo Young , Kim Woong-Kwon , Lee Jong-Lam
Published: August 2005

We report the enhancement of the electron injection by inserting a 1-nm-thick magnesium oxide (MgO) buffer layer between Al cathode and tris (8-hydroxyquinoline) aluminum in an inverted top-emitting organic light-emitting diode (OLED). The turn-on voltage of OLEDs decreased from 10 to 6 V and the luminance increased about 61% as the MgO interfacial layer was employed. The MgO interfacial layer played a role in reducing the energy barrier of electron injection, leading to the reduction of the turn-on voltage and the enhancement of luminance.
Bridging thin and thick skin solutions for alternating currents in cracked conductors
Authors: Saguy H. , Rittel D.
Published: August 2005

The alternating current potential drop (ACPD) technique is used to monitor surface cracks in electrical conductors. At high frequencies, the current flows in a superficial skin layer. Two distinct solutions are currently available for the thin and thick skin cases. However, there is no general solution that bridges these two modes in a seamless fashion. A numerical model is used to analyze the ACPD of a surface crack with uniform depth. A general solution is given that bridges the thin and thick skin solutions, which closely matches the numerical results, irrespective of the skin thickness.
Microfluidic interfacial tensiometry
Authors: Hudson Steven D. , Cabral João T. , Goodrum William J. , Beers Kathryn L. , Amis Eric J.
Published: August 2005

A microfluidic approach to measure interfacial tension σ of immiscible fluids rapidly is reported. This method rests upon quantitative real-time analysis of two-phase flow and drop-shape dynamics. Drops of prescribed dimension and spacing are produced, accelerated, and deformed under extensional flow. These measurements compare well with existing published data and demonstrate a wide range of accessible interfacial tension (e.g., from 2.5 to 60mN∕m).
Metrology of steel micronozzles using x-ray propagation-based phase-enhanced microimaging
Authors: Lee Wah-Keat , Fezzaa Kamel , Wang Jin
Published: August 2005

With high-energy and high-brilliance x-rays available at third-generation synchrotron sources, propagation-based phase-enhanced imaging was developed as a unique metrology technique to visualize the internal structure of high-pressure fuel-injection micronozzles. We have visualized the micrometer-scale machining and finishing defects inside a 200-μm-fuel-injection micronozzle in a 3-mm-thick steel housing using phase-enhanced x-ray imaging. Because of the phase enhancement, this new microimaging-based metrology technique has paved the way to directly study highly transient fluid dynamics in the micronozzles in situ and in real time, which is virtually impossible by any other means.
Chromatic Masking Revealed by the Standing Wave of Invisibility Illusion
Authors: McKeefry Declan J , Abdelaal Sherif , Barrett Brendan T , McGraw Paul V
Published: August 2005

We have used the standing wave of invisibility illusion (Macknik and Livingstone, 1998 Nature Neuroscience1 144–149) to examine the masking effects produced by a range of stimuli of varying chromatic and luminance contrast content. The pattern of masking was highly selective. Maximum effects were always obtained when the target and mask were identical in terms of their chromatic and/or luminance contrast composition, but were reduced as the angular separation in colour space between them was increased. Masking was of a monopolar nature, indicating the operation of rectified mechanisms selective for different combinations of colour and luminance contrast.
Perception of Chromatic Motion Requires Luminance Interaction
Authors: Baraas Rigmor C
Published: August 2005

There is an ongoing debate related to whether chromatic motion perception arises as a consequence of a chromatic signal only (eg Wandell et al 1999 Neuron24 901–909) or a signal that is essentially based on luminance processes (luminance artifacts) (Mullen et al 2003 Vision Research43 1235–1247). These two views conform to the idea that colour and luminance processes are physiologically independent (Livingstone and Hubel 1988 Science240 740–749), but according to other reports many primary cortical ‘V1’ cells respond to both colour and luminance contrast (eg Vidyasagar et al 2002 European Journal of Neuroscience16 945–956). A psychophysical task was designed to test whether possible interaction between luminance and chromatic contrast could account for perception of chromatic motion. It is shown that subjects respond in a manner that reflects involvement of both processes.
Effect of Scene Complexity on Colour Constancy with Real Three-Dimensional Scenes and Objects
Authors: Nascimento Sérgio M C , de Almeida Vasco M N , Fiadeiro Paulo T , Foster David H
Published: August 2005

The effect of scene complexity on colour constancy was tested with a novel technique in which a virtual image of a real 3-D test object was projected into a real 3-D scene. Observers made discriminations between illuminant and material changes in simple and complex scenes. The extent of colour constancy achieved varied little with either scene structure or test-object colour, suggesting a dominant role of local cues in determining surface-colour judgments.
Minimalist Surface-Colour Matching
Authors: Amano Kinjiro , Foster David H , Nascimento Sérgio M C
Published: August 2005

Some theories of surface-colour perception assume that observers estimate the illuminant on a scene so that its effects can be discounted. A critical test of this interpretation of colour constancy is whether surface-colour matching is worse when the number of surfaces in a scene is so small that any illuminant estimate is unreliable. In the experiment reported here, observers made asymmetric colour matches between pairs of simultaneously presented Mondrian-like patterns under different daylights. The patterns had either 49 surfaces or a minimal 2 surfaces. No significant effect of number was found, suggesting that illuminant estimates are unnecessary for surface-colour matching.
Does L/M Cone Opponency Disappear in Human Periphery?
Authors: Mullen Kathy T , Sakurai Masato , Chu William
Published: August 2005

We have assessed the optimal cone contrast sensitivity across eccentricity in human vision of the two cone-opponent mechanisms [L/M or red-green, and S/(L + M) or blue-yellow] and the luminance mechanism. We have used a novel stimulus, termed a ‘sinring’, that is a radially modulated sine-wave arc, Gaussian enveloped in both angular and radial directions. This stimulus overcomes the problem inherent in Gabor stimuli of confounding stimulus spatial frequency, size, and eccentricity and so allows contrast sensitivity to be tracked accurately into the periphery. Our results show that L/M cone opponency declines steeply across the human periphery and becomes behaviourally absent by 25–30 deg (in the nasal field). This result suggests that any L/M cone-opponent neurons found in primate peripheral retina beyond this limit are unlikely to be significant for colour contrast detection measured behaviourally.
Bohr's 1913 molecular model revisited
Authors: Svidzinsky Anatoly A. , Scully Marlan O. , Herschbach Dudley R.
Published: August 2005

It is generally believed that the old quantum theory, as presented by Niels Bohr in 1913, fails when applied to few electron systems, such as the H
2
molecule. Here, we find previously undescribed solutions within the Bohr theory that describe the potential energy curve for the lowest singlet and triplet states of H
2
about as well as the early wave mechanical treatment of Heitler and London. We also develop an interpolation scheme that substantially improves the agreement with the exact ground-state potential curve of H
2
and provides a good description of more complicated molecules such as LiH, Li
2
, BeH, and He
2
.
Identification of an interactor of cadmium ion-induced glycine-rich protein involved in regulation of callose levels in plant vasculature
Authors: Ueki Shoko , Citovsky Vitaly
Published: August 2005

Cadmium-induced glycine-rich protein (cdiGRP) is a cell wall-associated factor that increases callose levels in plant vasculature. To better understand the cdiGRP/callose regulation system, we identified a tobacco protein, GrIP (cdiGRP-interacting protein, GrIP), that associates with cdiGRP and localizes at the plant cell wall. Constitutive overexpression of GrIP enhanced the accumulation of the cdiGRP protein and callose in vasculature-associated cells with or without treatment with cadmium ions. ThatGrIPgene expression was not affected by cadmium ions indicated that GrIP does not directly modulate the callose levels induced by the treatment. Instead, GrIP most likely functions by further elevating the accumulated amount of cdiGRP, the expression of which is up-regulated by the cadmium ions. Interestingly, the levels ofcdiGRPmRNA were not affected by constitutive expression of GrIP, demonstrating that the enhancement in cdiGRP protein accumulation by GrIP overexpression occurs posttranslationally. Collectively, these observations suggest that GrIP interacts with cdiGRP and increases its level of accumulation; in turn, the elevated amounts of cdiGRP induce callose deposits in the plant cell walls. Therefore, GrIP and cdiGRP represent sequentially acting factors in a biochemical pathway that regulates callose accumulation in the plant vasculature.
The NH2 Terminus of RCK1 Domain Regulates Ca2+-dependent BKCa Channel Gating
Authors: Krishnamoorthy Gayathri , Shi Jingyi , Sept David , Cui Jianmin
Published: August 2005

Large conductance, voltage- and Ca2+-activated K+ (BKCa) channels regulate blood vessel tone, synaptic transmission, and hearing owing to dual activation by membrane depolarization and intracellular Ca2+. Similar to an archeon Ca2+-activated K+ channel, MthK, each of four α subunits of BKCa may contain two cytosolic RCK domains and eight of which may form a gating ring. The structure of the MthK channel suggests that the RCK domains reorient with one another upon Ca2+ binding to change the gating ring conformation and open the activation gate. Here we report that the conformational changes of the NH2 terminus of RCK1 (AC region) modulate BKCa gating. Such modulation depends on Ca2+ occupancy and activation states, but is not directly related to the Ca2+ binding sites. These results demonstrate that AC region is important in the allosteric coupling between Ca2+ binding and channel opening. Thus, the conformational changes of the AC region within each RCK domain is likely to be an important step in addition to the reorientation of RCK domains leading to the opening of the BKCa activation gate. Our observations are consistent with a mechanism for Ca2+-dependent activation of BKCa channels such that the AC region inhibits channel activation when the channel is at the closed state in the absence of Ca2+; Ca2+ binding and depolarization relieve this inhibition.
“Optical Patch-clamping”
Authors: Demuro Angelo , Parker Ian
Published: August 2005

We describe an optical technique using total internal reflection fluorescence (TIRF) microscopy to obtain simultaneous and independent recordings from numerous ion channels via imaging of single-channel Ca2+ flux. Muscle nicotinic acetylcholine (ACh) receptors made up of αβγδ subunits were expressed in Xenopus oocytes, and single channel Ca2+ fluorescence transients (SCCaFTs) were imaged using a fast (500 fps) electron-multiplied c.c.d. camera with fluo-4 as the indicator. Consistent with their arising through openings of individual nicotinic channels, SCCaFTs were seen only when a nicotinic agonist was present in the bathing solution, were blocked by curare, and increased in frequency as roughly the second power of [ACh]. Their fluorescence amplitudes varied linearly with membrane potential and extrapolated to zero at about +60 mV. The rise and fall times of fluorescence were as fast as 2 ms, providing a kinetic resolution adequate to characterize channel gating kinetics; which showed mean open times of 7.9 and 15.8 ms when activated, respectively, by ACh or suberyldicholine. Simultaneous records were obtained from >400 channels in the imaging field, and we devised a novel “channel chip” representation to depict the resultant large dataset as a single image. The positions of SCCaFTs remained fixed (<100 nm displacement) over tens of seconds, indicating that the nicotinic receptor/channels are anchored in the oocyte membrane; and the spatial distribution of channels appeared random without evidence of clustering. Our results extend single-channel TIRFM imaging to ligand-gated channels that display only partial permeability to Ca2+, and demonstrate an order-of-magnitude improvement in kinetic resolution. We believe that functional single-channel imaging opens a new approach to ion channel study, having particular advantages over patch-clamp recording in that it is massively parallel, and provides high-resolution spatial information that is inaccessible by electrophysiological techniques.