bluuebunny/crossref_metadata_2025 huggingface dataset:
The Account of Persia and Cyrus's Persian Education in Xenophon'sCyropaedia
Authors: Whidden Christopher
Published: October 2007

TheCyropaediais a biographical account of what Cyrus, the founder of the Persian Empire, knew in order to rule human beings. This essay focuses on Cyrus's twofold Persian education, which consisted of his conventional and heterodox educations. The former emphasized the rule of law, while the latter stressed the need for absolute rule by a single leader. In order to evaluate Cyrus's revolution, one must grasp the relative strengths and weaknesses of the Persian regime that educated him, especially in light of the impressive but short-lived empire he founded. In the end, theCyropaediaunfolds as a deeply ironic work. Despite Cyrus's prodigious wisdom, the empire he founded was for Xenophon neither unequivocally lasting nor good. In this sense, Xenophon's own knowledge rivals and supercedes that of Cyrus, insofar as Xenophon realized that wisdom is no match for the chaotic world of politics, a sobering and realistic outlook still applicable today.
Evolutionary design of modular robotic arms
Authors: Chocron O.
Published: October 2007

This paper proposes a method for task based design of modular serial robotic arms using evolutionary algorithms (EA). We introduce a 3D kinematics and a global optimization for both topology and configuration from task specifications. The search features revolute as well as prismatic joints and any number of DOF to build up a solution without using any design knowledge. A study of the evolution dynamics gives some keys to set evolution parameters that enable artificial evolution. An adapted algorithm dealing with the topology/configuration search tradeoff is proposed, descibed, and discussed. Illustrations of the algorithms results are given and conclusions are drawn from their analysis. Perspectives of this work are given, extending its reach to control and complex system design.
Cross-species infection of hepatitis E virus in a zoo-like location, including birds
Authors: ZHANG W. , SHEN Q. , MOU J. , YANG Z. B. , YUAN C. L. , CUI L. , ZHU J. G. , HUA X. G. , XU C. M. , HU J.
Published: October 2007

Hepatitis E virus (HEV) is a zoonotic pathogen of which several species of animals are considered to be reservoirs. Thirty-eight faecal samples, obtained from 22 species of animals including birds in a wildlife first-aid centre in Eastern China, were tested for HEV RNA. Our survey revealed that in total 28·9% (95% confidence interval 14·5–43·4) of the faecal samples from various mammals and birds were HEV RNA positive. Sequence and phylogenetic analyses of the 11 isolates demonstrated that all sequences clustered in genotype 4 with 96–100% identity to each other. In addition, serum samples from seven animal handlers have shown that five (71·4%) were seropositive. The findings imply that cross-species infection of HEV had probably occurred in this zoo-like location, and moreover, birds can be infected naturally with mammalian HEV.
The rapid identification ofClostridium perfringensas the possible aetiology of a diarrhoeal outbreak using PCR
Authors: LOH J. P. , LIU Y. C. , CHEW S. W. , ONG E. S. , FAM J. M. , NG Y. Y. , TAYLOR M. B. , OOI E. E.
Published: October 2007

A gastroenteritis outbreak occurred in a military camp where a laboratory and epidemiological investigation was carried out. The early onset of symptoms indicated probable food contamination withClostridium perfringens. Stool samples collected from affected patients were tested within 4 h via real-time polymerase chain reaction (PCR) for the presence of theC. perfringens plcgene. Ten out of the 12 stool samples were positive. Confirmation of the molecular test results was carried out by enumeration ofC. perfringensin stool by culture and shown to be in excess of 106spores/g stool. The isolates obtained from culture were further analysed by PCR for the presence of the chromosomal enterotoxin (cpe) gene. Based on the clinical symptoms, epidemiological and laboratory investigations,C. perfringenswas implicated as the aetiological agent. The ability to conduct real-time PCR analysis greatly shortens the time to diagnosis and allows for preventive and control measures to be effected quickly.
Identification of quantitative trait loci controlling seed physical and nutrient traits in cotton
Authors: Song Xian-Liang , Zhang Tian-Zhen
Published: October 2007

Cotton (Gossypium spp.) is an important source of edible oil and protein meals. Complex genetics and strong environmental effects hinder progress in seed quality trait breeding in this species. The use of molecular markers can improve an understanding of the genetic factors conditioning seed quality traits, and is expected to assist in selection of superior genotypes. This study was conducted to identify quantitative trail loci (QTL) associated with seed physical and nutrient traits in cotton. To achieve this objective, a population of 140 BC1S1 lines developed from a cross between ‘TM-1’ and ‘Hai7124’ was evaluated in 2003 and 2004. A linkage map consisting of 918 markers from this population was used to identify QTL using QTLNetwork-2.0 software. Eleven single QTL were identified for kernel percentage, kernel oil percentage, kernel protein percentage and seven amino acids (Asp, Ser, Gly, Ile, Leu, Phe and Arg). Phenotypic variation explained by each individual QTL ranged from 10.89 to 46.28%. Two epistatic QTL for Cys and Leu were detected, explaining 9.55 and 4.43% of the phenotypic variation. These QTL detected for seed quality traits in cotton are expected to be useful for further breeding programmes targeting development of cotton with improved nutrient quality.
Nymphaeaceae: a basal angiosperm family (ANITA grade) with a fully developed embryo
Authors: Baskin Carol C. , Baskin Jerry M.
Published: October 2007

Rudimentary, broad and small linear embryos occur among members of the most primitive (basal) extant angiosperms, collectively called the ANITA grade (i.e.Amborella,NymphaealesandAustrobaileyales).Amborella(rudimentary) andAustrobaileyales(rudimentary inAustrobaileyaceae,IlliciaceaeandSchisandraceaeand small linear inTrimeniaceae) have kinds of embryos that are known to be underdeveloped; consequently, they must grow inside the seed prior to radicle emergence (germination). On the other hand, it is not known if broad embryos need to grow before radicles can emerge, and whether they are underdeveloped or fully developed. Thus, we addressed the question: ‘Is the broad embryo ofNymphaealesalso underdeveloped?’. Although the embryo length : seed length ratios inNymphaeaAlbert Greenburg,N.capensisvar.zanzibariensisandN.immutabiliswere 0.311, 0.349 and 0.234, respectively, embryos did not grow prior to radicle emergence. Thus, they are fully developed at seed maturity. IfAmborellaandNymphaealesare equally the most basal angiosperms, as some molecular phylogenetic studies indicate, then we must conclude that the broad and rudimentary embryos are equally primitive.
Molecular cloning and characterization of aLEAFY-like gene highly expressed in developing soybean seeds
Authors: Meng Qingchang , Zhang Chunhong , Huang Fang , Gai Junyi , Yu Deyue
Published: October 2007

LEAFY (LFY)-like proteins are plant-specific transcription factors that play essential roles in plant growth and development. In this study, aLEAFYhomologue in soybean [Glycine max(L.) Merr.], designated asGmLFY, was cloned from inflorescences by the rapid amplification of cDNA ends (RACE) method. Sequence analysis showed thatGmLFYcDNA contained a 1221 bp open reading frame, encoding 407 amino acid residues with typical characteristics of transcription factors. Subcellular localization in onion epidermal cells indicated that GmLFY protein was located in the nucleus. Analysis of theGmLFYgenomic structure showed that theGmLFYgene has two introns with similar spliced sites asLFY-like genes in other plants. Reverse transcription-polymerase chain reaction (RT-PCR) analysis indicated thatGmLFYwas predominantly expressed in reproductive organs, such as inflorescences, pods and developing seeds. Further analysis showed that the expression level ofGmLFYwas higher in the middle stage than in the early or late stages of seed development, suggesting an essential regulatory role of GmLFY in soybean seed development.
Loss of desiccation tolerance during germination in neo-tropical pioneer seeds: implications for seed mortality and germination characteristics
Authors: Daws Matthew I. , Bolton Sheina , Burslem David F.R.P. , Garwood Nancy C. , Mullins Christopher E.
Published: October 2007

Orthodox, desiccation-tolerant seeds lose desiccation tolerance during germination. Here, we quantify the timing of the loss of desiccation tolerance, and explore the implications of this event for seed mortality and the shape of germination progress curves for pioneer tree species. For the nine species studied, all seeds in a seedlot lost desiccation tolerance after the same fixed proportion of their time to germination, and this proportion was fairly constant across the species (0.63–0.70). The loss of desiccation tolerance after a fixed proportion of the time to germination has the implication that the maximum number of seeds in a seedlot that can be killed by a single drying event during germination (Mmax) increases with an increasing time to 50% germination (t50) and an increasing slope of the germination progress curve. Consequently, to prevent the seed population from becoming highly vulnerable to desiccation-induced mortality, species with a greatert50would be expected to have a shallower germination progress curve. In conclusion, these data suggest that the loss of desiccation tolerance during germination may constitute a significant, but previously unexplored, source of mortality for seeds in seasonal environments with unpredictable rainfall.
Multiple environmental signals required for embryo growth and germination of seeds of Selinum carvifolia (L.) L. and Angelica sylvestris L. (Apiaceae)
Authors: Vandelook Filip , Bolle Nele , Van Assche Jozef A.
Published: October 2007

Germination and dormancy breaking requirements were studied in Selinum carvifolia (L.) L. and Angelica sylvestris L. (Apiaceae). Seeds of these two species have an underdeveloped embryo and are morpho-physiologically dormant. The embryo does not start to grow until physiological dormancy is broken by cold stratification. Incubating seeds at fluctuating temperatures in the light, after cold stratification, had a stimulating effect on embryo growth and seed germination. Seeds of S. carvifolia and A. sylvestris have non-deep simple morphophysiological dormancy (MPD), since gibberellic acid (GA3) could substitute for cold stratification. This is the first report of non-deep simple MPD that is broken by cold stratification in the Apiaceae. Under natural conditions, physiological dormancy is broken by low temperature conditions during winter. Embryo growth and germination occur in a short time interval when temperatures start rising in early spring. Due to the fact that multiple environmental signals regulate dormancy, seedling emergence in these species is timed very accurately in spring.
Artefacts between disciplines. The toothbrush and the axe
Authors: Garrow Duncan , Shove Elizabeth
Published: October 2007

This paper takes the form of a dialogue between an archaeologist and a sociologist. In recent years, interdisciplinary working has become increasingly fashionable within academia. The aim of our exchange was to establish exactly what implications this way of working has for understandings of material culture. Our methodology was simple, involving the ‘archaeological’ and ‘sociological’ analysis of two different objects. In undertaking this work, we hoped to bring about new or different understandings of the objects under scrutiny. The process was indeed successful, but not necessarily in the ways we had expected. Ultimately, it revealed a complex set of questions about how the materials of culture are conceptualized and understood, and led us to a renewed appreciation of the theoretical and methodological qualities of what we do within our respective disciplines.
Objects as such and objects in contexts. Things and equipment
Authors: Hahn Hans Peter
Published: October 2007

In the last two or three decades, material culture as a topic of scientific study has experienced a real boom. Focusing on everyday objects, their contexts and meanings, material culture studies offers important approaches for several disciplines within the humanities. The aim of this new wave of research is to improve the understanding of social practices in a wider sense and thereby contribute to the understanding of societies themselves. Given this ambitious goal, and the wide range of disciplines engaged in studying material culture, the new approach will only have a future if interdisciplinary debates are initiated and succeed in making reciprocal benefits. In particular, the complementarities of different disciplinary methodologies should result in useful synergies. If material culture studies is seen only as a domain within anthropology (or any other discipline) then we risk it coming to a dead end (Bertrand and Jewsiewicki 1999, 181; Hahn 2005, 12). This is the larger context in which I see the relevance of the present essay and, before going into details, I would like to express my support to the ideas expressed by Garrow and Shove.
Artefacts in quarantine?
Authors: Knappett Carl
Published: October 2007

As the authors situate the discussion in their offices, let me also begin in mine. On my way home from the office there will be many things around me. They will mostly be familiar and go largely unnoticed. I will take my keys off the desk and lock the door behind me. I will walk along the corridor, through the swing doors, down the stairs, unlock my bike, and so on. Desk, keys, door, carpet, windows, stairs, lock, bike – these are all objects with which I interact. But do I necessarily notice them? As long as there is ‘smooth coping’, as long as these objects are ready to hand (Wheeler 2005, 129), then they remain in the background. These are not objects that hold me in their gaze; I do not ‘encounter’ them, in the sense of encountering, meeting or bumping into a person.
‘Source of the Tigris’. Event, place and performance in the Assyrian landscapes of the Early Iron Age
Authors: Harmanşah Ömür
Published: October 2007

Performative engagements with specific, culturally significant places were among the primary means of configuring landscapes in the ancient world. Ancient states often appropriated symbolic or ritual landscapes through commemorative ceremonies and building operations. These commemorative sites became event-places where state spectacles encountered and merged with local cult practices. The Early Iron Age inscriptions and reliefs carved on the cave walls of the Dibni Su sources at the site of Birkleyn in Eastern Turkey, known as the ‘Source of the Tigris’ monuments, present a compelling paradigm for such spatial practices. Assyrian kings Tiglath-pileser I (1114–1076 B.C.) and Shalmaneser III (858–824 B.C.) carved ‘images of kingship’ and accompanying royal inscriptions at this impressive site in a remote but politically contested region. This important commemorative event was represented in detail on Shalmaneser III's bronze repoussé bands from Imgul-Enlil (Tell Balawat) as well as in his annalistic texts, rearticulating the performance of the place on public monuments in Assyrian urban contexts. This paper approaches the making of the Source of the Tigris monuments as a complex performative place-event. The effect was to reconfigure a socially significant, mytho-poetic landscape into a landscape of commemoration and cult practice, illustrating Assyrian rhetorics of kingship. These rhetorics were maintained by articulate gestures of inscription that appropriated an already symbolically charged landscape in a liminal territory and made it durable through site-specific spatial practices and narrative representations.
Broadband shortwave calibration results for East Asian Regional Experiment 2005
Authors: Uchiyama A. , Yamazaki A. , Matsuse K. , Kobayashi E.
Published: October 2007

In order to accurately estimate radiative forcing from observations, it is necessary to make accurate measurements and to maintain the calibration of the instruments used. The ABC‐Asia project involves long‐term measurements of solar irradiance. For EAREX 2005, we investigated calibration methods and procedures for pyranometers and pyrheliometers as the first phase of the project. Several methods for calibrating pyranometers and pyrheliometers were tried. It was most troublesome to take account of the deviation from a cosine law response in side‐by‐side intercomparisons of pyranometers. A method using a collimation tube was one of the easiest. In addition, a new method to determine both the sensitivity and the deviation from a cosine law response was developed. In this method, the direct component is extracted from the global irradiance measurement and utilized. The dispersion of sensitivity among these methods was ±1%. There is also a possibility of year‐to‐year variations in sensitivity. It is therefore recommended that each pyranometer be recalibrated every 2 or 3 a. The sensitivity of the pyrheliometer was determined by comparing it with an absolute cavity radiometer calibrated at the World Radiation Center (Davos, Switzerland). The dispersion of sensitivity for pyrheliometers was less than 0.2%. For the pyrheliometers the determined values were almost the same as those provided by the radiometer manufacturer.
Submicron aerosol size distributions and cloud condensation nuclei concentrations measured at Gosan, Korea, during the Atmospheric Brown Clouds–East Asian Regional Experiment 2005
Authors: Yum Seong Soo , Roberts Greg , Kim Jong Hwan , Song Keunyong , Kim Dohyeong
Published: October 2007

Submicron aerosol size distributions, CN and CCN concentrations at a constant supersaturation of 0.6% were measured at a relatively remote coastal site at Gosan in Jeju Island, Korea, during the ABC‐EAREX from 11 March to 8 April 2005. The average CN concentrations were 6088 ± 3988, 5231 ± 2454 and 3513 ± 1790 cm−3, respectively, for the three major air mass types classified by their origins. The corresponding CCN concentrations were 2393 ± 1156, 2897 ± 1226 and 1843 ± 585 cm−3. The type III air mass was the closest to maritime origins, but these lowest concentrations at Gosan were an order of magnitude higher than those of clean marine boundary layer, indicating that regardless of air mass designation springtime submicron aerosols at Gosan were under steady continental influences. Distinct new particle formation and growth events occurred on 6 d, when clear sky weather conditions prevailed that brought air from northern China, Mongolia or Russia by anticyclonic circulations. Simultaneous occurrence of these events at a western coastal site in the Korean Peninsula 350 km north of Gosan suggests that these events were not local but at least regional‐scale events. CCN concentrations were predicted with the aerosol size distributions and the assumption of particles being composed of (NH4)2SO4. The predicted to measured CCN concentration ratio was 1.27 ± 0.29 and the r2 was 0.77 for the whole measurement period. The type I air mass that has the most continental influences showed a slight tendency to overpredict CCN concentrations but the good agreement overall suggests that springtime Gosan aerosols act almost like ammonium sulfate as far as CCN activity is concerned, almost regardless of air mass origin.
Changes in the hydrological cycle, ocean circulation, and carbon/nutrient cycling during the last interglacial and glacial transition
Authors: Gröger M. , Maier‐Reimer E. , Mikolajewicz U. , Schurgers G. , Vizcaíno M. , Winguth A.
Published: October 2007

A complex Earth system model has been forced by insolation changes for the last interglacial (LIG) for which geological records evidence a climate cooling that culminated in the last glacial inception. During an early warm period (127–125 ka B.P.) the Arctic/North Atlantic drainage basin north of 30°N receives ∼27,000 m3/s more fresh water mainly imported across the watershed of North America compared to a cooler period centered around 115 ka B.P. Together with a strong surface warming by up to 2 K, this results in a weaker North Atlantic overturning (reduced by ∼20%). Sea ice cover is reduced by 3 × 106 km2 in the Northern Hemisphere, stimulating a stronger productivity in the Barents and Kara seas. In the North Pacific a lowered salinity and a surface warming of more than 3 K increase the stratification. The eastern Pacific becomes nutrient poorer, which leads to a reduction in the export production in areas with vigorous upwelling. The climate cooling in the course of the LIG induces a carbon release by the terrestrial biosphere of 308 Gt, which is counteracted by an oceanic/sedimentary uptake of 290 Gt. The rest remains in the atmosphere increasing the pCO2 by 9 ppm. The large oceanic CO2 uptake corresponds to a rise of the calcite lysocline of about 300 m in the midlatitude Atlantic. The chemically interactive carbonate sediment pool in the Atlantic is reduced by 10%. For nearly the entire North Atlantic, our results are contradictory to the common interpretation of carbonate preservation proxies as a reliable tool for monitoring changes in deep water circulation.
Modeling the effects of radial diffusion and plasmaspheric hiss on outer radiation belt electrons
Authors: Lam M. M. , Horne R. B. , Meredith N. P. , Glauert S. A.
Published: October 2007

We simulate the behaviour of relativistic (976 keV) electrons in the outer radiation belt (3 ≤ L ≤ 7) during the first half of the CRRES mission. We use a 1d radial diffusion model with losses due to pitch‐angle scattering by plasmaspheric hiss expressed through the electron lifetime calculated using the PADIE code driven by a global Kp‐dependent model of plasmaspheric hiss intensity and fpe/fce. We use a time and energy‐dependent outer boundary derived from observations. The model reproduces flux variations to within an order of magnitude for L ≤ 4 suggesting hiss is the dominant cause of electron losses in the plasmasphere near the equator. At L = 5 the model reproduces significant variations but underestimates the size of the variability. We find that during magnetic storms hiss can cause significant losses for L ≤ 6 due to its presence in plumes. Wave acceleration is partially represented by the boundary conditions.
Molecular nitrogen Carroll‐Yoshino v′ = 0 emission in the thermospheric dayglow as seen by the Far Ultraviolet Spectroscopic Explorer
Authors: Bishop James , Stevens Michael H. , Feldman Paul D.
Published: October 2007

Molecular nitrogen (N2) Carroll‐Yoshino excitation is of considerable interest in the analysis of EUV‐FUV observations obtained from several solar system objects (Earth, Titan, and Triton). The fundamental c4′(0, 0) band at 958 Å is a strong transition excited by photoelectron impact and hence is bright under optically thin conditions. On Earth c4′(0, 0) is optically thick near the altitude of peak photoelectron excitation and the emergent (0, 0) emission is weak. Past analyses of EUV airglow spectra focused on the roles of (0, v″ ≤ 2) photon redistribution and predissociation enhancement resulting from multiple scattering in accounting for reduced emission. The role of (0, v″ > 2) fluorescence was deemed minor. Now, high‐resolution dayglow measurements by the Far Ultraviolet Spectroscopic Explorer (FUSE) made in September 1999 reveal c4′(0, v″ = 6–9) fluorescence bands much brighter than expected. The results of an analysis of FUSE dayside disk measurements are presented, and the observed (0, v″) emission is discussed in the context of results from a multiple scattering model. The c4′(0, 9) band in particular stands out as a potentially useful remote sensing observable.
Data assimilation of LANL satellite data into the Salammbô electron code over a complete solar cycle by direct insertion
Authors: Maget V. , Bourdarie S. , Boscher D. , Friedel R. H. W.
Published: October 2007

Past work of data reanalysis using the Salammbô three‐dimensional code and LANL satellite data was done on a magnetic storm timescale. Here, we focus on the solar cycle timescale reanalysis. We study the accuracy of the reconstitution of the electron radiation belts from 1990 to 2005 using data from Los Alamos instruments on GPS and GEO spacecrafts. First, we simulate the 9 October 1990 storm. By predicting fluxes at CRRES orbit, we estimate a confidence level and propose quantitative limitations on the current state of the art for chorus wave‐particle interaction modeling. By performing a run covering 15 a, we have been able to distinguish dynamics of different timescales and compare and validate our results with the statistical radiation belt models AE‐8 and CRRESELE. The main conclusion is that the history of the radiation belts is of prime importance in order to best fit their real state. Data reanalysis is a new and valuable way to describe them.
Ligand‐independent activation of vascular endothelial growth factor receptor 1 by low‐density lipoprotein
Authors: Usui Ryosuke , Shibuya Masabumi , Ishibashi Shun , Maru Yoshiro
Published: October 2007

Elevated serum low‐density lipoprotein (LDL) is a risk factor for atherosclerotic disorders. However, prominent atherosclerosis, which has been observed in LDL receptor (LDLR)‐knockout mice, has diminished the significance of LDLR as a cause of atherosclerosis, while elaborate studies have focused on the receptors for denatured LDL. Here we report that native LDL (nLDL) activates vascular endothelial growth factor (VEGF) receptor 1 (VEGFR1) but not VEGFR2 through LDLR and is as potent as VEGF in macrophage migration. Binding and co‐endocytosis of VEGFR1 and LDLR were enhanced by nLDL, which is concomitant with ubiquitination‐mediated degradation of VEGFR1. We propose that LDLR‐mediated use of VEGFR1 by nLDL could be a potential therapeutic target in atherosclerotic disorders.
Achieving plane wave accuracy in linear-scaling density functional theory applied to periodic systems: A case study on crystalline silicon
Authors: Skylaris Chris-Kriton , Haynes Peter D.
Published: October 2007

Linear-scaling methods for density functional theory promise to revolutionize the scope and scale of first-principles quantum mechanical calculations. Crystalline silicon has been the system of choice for exploratory tests of such methods in the literature, yet attempts at quantitative comparisons under linear-scaling conditions with traditional methods or experimental results have not been forthcoming. A detailed study using the ONETEP code is reported here, demonstrating for the first time that plane wave accuracy can be achieved in linear-scaling calculations on periodic systems.
High aspect ratio surface relief structures by photoembossing
Authors: Hermans Ko , Wolf Florian K. , Perelaer Jolke , Janssen Rene A. J. , Schubert Ulrich S. , Bastiaansen Cees W. M. , Broer Dirk J.
Published: October 2007

Photoembossing is a convenient and economical process to form complex surface relief structures in polymer thin films. We have improved the aspect ratio of photoembossed microstructures by adding t-butyl hydroquinone (TBHQ) to the polymerization mixture. The mechanism that is proposed is based on the radical transfer principle, where TBHQ converts acrylate radicals into stable phenol radicals that at elevated temperatures act as latent initiators, thereby controlling the kinetics without changing the number of polymerization active sites. As a result, the aspect ratio can be improved with a factor of 5–7 in comparison with previously proposed similar processes.
Spectral identification of fullerene C82 isomers
Authors: Gao Bin , Liu Lei , Wang ChunRu , Wu ZiYu , Luo Yi
Published: October 2007

Ultraviolet photoelectron spectra (UPS) of C82 isomers have been calculated using hybrid density functional theory in combination with the Gelius model [Proceedings of the International Conference on Electron spectroscopy, edited by D. A. Shirley (North-Holland, Amsterdam, 1972), p. 311; J. Electron Spectrosc. Relat. Phenom. 5, 985 (1974)]. The calculated UPS spectra are found to be isomer dependent and in good agreement with the experimental counterparts. Near-edge x-ray absorption fine structure (NEXAFS), x-ray photoelectron spectroscopy (XPS), x-ray emission spectroscopy, and the resonant inelastic x-ray scattering (RIXS) spectra of three important isomers [3(C2), 6(Cs), and 9(C2v)] have also been simulated. Strong isomer dependence has also been found for NEXAFS, XPS, and RIXS spectra.
Maximum likelihood estimators for generalized Cauchy processes
Authors: Konno Hidetoshi , Watanabe Fumitoshi
Published: October 2007

Maximum likelihood estimator (MLE) for a generalized Cauchy process (GCP) is studied with the aid of the method of information geometry in statistics. Our GCP is described by the Langevin equation with multiplicative and additive noises. The exact expressions of MLEs are given for the two cases that the two types of noises are uncorrelated and mutually correlated. It is shown that the MLEs for these two GCPs are free from divergence even in the parameter region wherein the ordinary moments diverge. The MLE relations can be regarded as a generalized fluctuation-dissipation theorem for the present Langevin equation. Availability of them and of some other higher order statistics is demonstrated theoretically and numerically.
Direct measurement of momentum relaxation time in wurtzite InN
Authors: Chang Yu-Ming , Gwo Shangjr
Published: October 2007

In this paper, we demonstrate that the momentum relaxation time of photoexcited carriers in wurtzite InN can be directly determined by investigating the rapid dephasing nature of coherent upper-branched longitudinal optical phonon-plasmon coupling (L+) mode. It is found that coherent L+ mode is a plasmonlike vibration mode and its dephasing time reduces from 120to60fs when the photoexcited carrier density increases from 2×1017∕cm3to2×1018∕cm3. The measured dephasing time is attributed to the momentum relaxation of photoexcited carriers, which is governed by the screened Coulomb interaction among photoexcited and background carriers in the bulk region of InN.
Dynamics and morphology development in electrospun fibers driven by concentration sweeps
Authors: Dayal Pratyush , Kyu Thein
Published: October 2007

The present article describes the modeling and simulation of the dynamics of the electrospinning process coupled with the spatio-temporal evolution of fiber morphology driven by concentration sweeps. The electrospinning process has been modeled based on an array of beads connected by Maxwell’s elements in a cylindrical shell to describe the force balance between Coulombic and viscoelastic forces at the surface of the jet. The phase separation dynamics has been calculated in the framework of the Cahn-Hilliard time-evolution equation by incorporating Flory-Huggins free energy for liquid-liquid demixing in conjunction with solvent evaporation through the fiber surface. The simulations based on the coupling of these two processes have revealed in situ morphology development registering all structural forming processes such as polymer droplets, interconnected spinodal structure, and the porous structure along the spinline. The simulated porous fiber shows a striking resemblance to the experimental finding.
Rotational dynamics of a superhelix towed in a Stokes fluid
Authors: Jung Sunghwan , Mareck Kathleen , Fauci Lisa , Shelley Michael J.
Published: October 2007

Motivated by the intriguing motility of spirochetes (helically shaped bacteria that screw through viscous fluids due to the action of internal periplasmic flagella), we examine the fundamental fluid dynamics of superhelices translating and rotating in a Stokes fluid. A superhelical structure may be thought of as a helix whose axial centerline is not straight, but also a helix. We examine the particular case in which these two superimposed helices have different handedness, and employ a combination of experimental, analytic, and computational methods to determine the rotational velocity of superhelical bodies being towed through a very viscous fluid. We find that the direction and rate of the rotation of the body is a result of competition between the two superimposed helices; for small axial helix amplitude, the body dynamics is controlled by the short-pitched helix, while there is a crossover at larger amplitude to control by the axial helix. We find far better, and excellent, agreement of our experimental results with numerical computations based upon the method of Regularized Stokeslets than upon the predictions of classical resistive force theory.
Numerical simulation of thermal convection of a viscoelastic fluid in a porous square box heated from below
Authors: Fu Ceji , Zhang Zhiyong , Tan Wenchang
Published: October 2007

Thermal convection phenomena of viscoelastic fluids in a closed-top porous square box heated from below are studied numerically based on a modified Darcy’s law, where two characteristic time constants λ and ε are used to describe the viscoelastic properties of the fluid. Results for three set values of λ and ε are obtained for a Darcy-Rayleigh number up to 400, and show very different heat transport characteristics from those of Newtonian fluids. Two types of thermal convection are shown to be possible. Oscillatory convection due to the viscoelastic properties of the fluid precedes the onset of steady convection due to thermal boundary instability. After steady convection sets in, it tends to suppress oscillatory convection. The interaction between the two types of thermal convection causes the flow patterns in the porous layer to be more complicated than those of Newtonian fluids. Furthermore, thermal convection of viscoelastic fluids in porous layers undergoes earlier bifurcations with increase of Ra than those of Newtonian fluids and the occurrence of bifurcation is earlier for larger values of λ∕ε in our study. Finally, our numerical results show that scaling laws exist for thermal convection of viscoelastic fluids in porous layers, and specific scaling laws were obtained by the least-squares fitting technique to describe the Nu versus Ra relationship in different regimes of Ra and for the three cases studied in this work.
A compact high power pulsed modulator based on spiral Blumlein line
Authors: Liu Jinliang , Yin Yi , Ge Bin , Cheng Xinbing , Feng Jiahuai , Zhang Jiande , Wang Xinxin
Published: October 2007

A compact high power pulsed modulator based on spiral water Blumlein line, which consists of primary storage capacitors, a Tesla transformer, a spiral Blumlein line of water dielectric, and a field-emission diode, is described. The experimental results showed that the diode voltage is more than 500kV, the electron beam current of diode is about 32kA, and the pulse duration is about 180ns. The distributions for electrical field in the spiral water Blumlein line were obtained by the simulations. In addition, the process of the charging a spiral Blumlein line was simulated through the PSPICE software to get the wave form of charging voltage of pulse forming line, the diode voltage, and diode current of modulator. The theoretical and simulated results are in agreement. This accelerator is very compact and works stably and reliably.
Xe capillary target for laser-plasma extreme ultraviolet source
Authors: Inoue Takahiro , Okino Hideyasu , Nica Petru Edward , Amano Sho , Miyamoto Shuji , Mochizuki Takayasu
Published: October 2007

A cryogenic Xe jet system with an annular nozzle has been developed in order to continuously fast supply a Xe capillary target for generating a laser-plasma extreme ultraviolet (EUV) source. The cooling power of the system was evaluated to be 54W, and the temperature stability was ±0.5K at a cooling temperature of about 180K. We investigated experimentally the influence of pressure loss inside an annular nozzle on target formation by shortening the nozzle length. Spraying caused by cavitation was mostly suppressed by mitigating the pressure loss, and a focused jet was formed. Around a liquid-solid boundary, a solid-Xe capillary target (100∕70μmϕ) was formed with a velocity of ⩽0.01m∕s. Laser-plasma EUV generation was tested by focusing a Nd:YAG laser beam on the target. The results suggested that an even thinner-walled capillary target is required to realize the inertial confinement effect.
ac modeling and impedance spectrum tests of the superconducting magnetic field coils for the Wendelstein 7-X fusion experiment
Authors: Ehmler Hartmut , Köppen Matthias
Published: October 2007

The impedance spectrum test was employed for detection of short circuits within Wendelstein 7-X (W7-X) superconducting magnetic field coils. This test is based on measuring the complex impedance over several decades of frequency. The results are compared to predictions of appropriate electrical equivalent circuits of coils in different production states or during cold test. When the equivalent circuit is not too complicated the impedance can be represented by an analytic function. A more detailed analysis is performed with a network simulation code. The overall agreement of measured and calculated or simulated spectra is good. Two types of short circuits which appeared are presented and analyzed. The detection limit of the method is discussed. It is concluded that combined high-voltage ac and low-voltage impedance spectrum tests are ideal means to rule out short circuits in the W7-X coils.
Plasma characteristics in a solenoidal inductive/capacitive discharge under a weak dc magnetic field
Authors: Lee Min-Hyong , Chung Chin-Wook
Published: October 2007

Plasma parameters such as electron temperatures, plasma potentials, and plasma densities in a solenoidal inductive/capacitive discharge immersed in a weak dc magnetic field are investigated by measuring electron energy distribution functions (EEDF). Measured EEDFs in a dc magnetic field show the typical characteristics of the local electron kinetics. The magnetic field reduces the heat flow to the electrons at the discharge center while it heats up the electrons at the discharge radial boundary. The change in the plasma potential with respect to the magnetic field at various radial positions is also discussed. It is found that the radial profile of the plasma density predominately changes with varying the magnetic field, and the magnetic field can be used to control the radial uniformity of the plasma density in the solenoidal inductive/capacitive discharge.
Electrical microfluidic pressure gauge for elastomer microelectromechanical systems
Authors: Kartalov Emil P. , Maltezos George , French Anderson W. , Taylor Clive R. , Scherer Axel
Published: October 2007

We report on an electrical microfluidic pressure gauge. A polydimethylsiloxane microvalve closes at a characteristic applied pressure determined by the material’s properties and the valve’s dimensions. Hence, when the same pressure is applied to all valves of a heterogeneous valve array, some valves close while others remain open. The state of the array is combined with knowledge of the respective characteristic closing pressures of the individual valves to yield an estimate of the applied pressure. The state of each valve is obtained by electrical measurements, since the electrical resistance of the respective underlying fluid-filled channel increases by at least two orders of magnitude as the valve closes and its insulating elastomer material interrupts the electrical circuit. The overall system functions as a pressure gauge with electrical readout. This device would be a critical component in active pressure-regulation loops in future integrated microfluidic systems.
Metal-insulator transition in SrTiO3 induced by field effect
Authors: Shibuya Keisuke , Ohnishi Tsuyoshi , Sato Taisuke , Lippmaa Mikk
Published: October 2007

We have induced a metal-insulator transition in nondoped SrTiO3 by an electric field. The sheet carrier concentration of a SrTiO3 single-crystal surface was increased by electrostatic doping to 3.4×1012cm−2. A crossover from an insulating phase to a metallic state was clearly observed. The conduction mechanism in the insulating phase was explained in terms of thermal carrier excitation. By applying a gate field, the activation energy of the thermally excited carriers was reduced, eventually reaching zero at a critical gate field and thus converting the transistor channel to a metallic state. The sheet resistance was found to scale with temperature in both insulating and metallic states.
The quasisteady shape of a deformable bubble in a weakly nonuniform potential flow
Authors: Yariv Ehud , Frankel Itzchak
Published: October 2007

We consider the small-Weber-number quasisteady deformation of a bubble moving in an inviscid liquid undergoing an inhomogeneous background flow. The use of polyadic spherical harmonics [Brenner, Chem. Eng. Sci. 19, 631 (1964)] allows for the treatment of general (nonaxisymmetric) irrotational flows. We correct the (overestimated) volumetric expansion value appearing in the literature, which resulted from an oversight in the application of Bernoulli’s equation.
Lossless all-optical phase gate using a polarization-division Sagnac interferometer applicable to a waveguide-type Kerr medium
Authors: Matsuda Nobuyuki , Mitsumori Yasuyoshi , Kosaka Hideo , Edamatsu Keiichi , Shimizu Ryosuke
Published: October 2007

We propose an apparatus that realizes direct observation of nonlinear phase shifts induced by cross-phase modulation. The apparatus is based on a polarization-division Sagnac interferometer incorporating Faraday rotators, which, in principle, enables phase robustness, flexibility, and lossless operation. Here, we present the measurement of nonlinear phase shifts in a photonic crystal fiber, demonstrating the advantage of our system in its application to waveguide-type Kerr media. This apparatus is applicable to lossless all-optical phase gates and switches.
Axial orientation of molecular-beam-epitaxy-grown Fe3Si∕Ge hybrid structures and its degradation
Authors: Maeda Yoshihito , Jonishi Takafumi , Narumi Kazumasa , Ando Yu-ichiro , Ueda Koji , Kumano Mamoru , Sadoh Taizoh , Miyao Masanobu
Published: October 2007

The axial orientation of molecular-beam-epitaxy (MBE)-grown Fe3Si(111)∕Ge(111) hybrid structures was investigated by Rutherford backscattering spectroscopy. We confirmed that during MBE above 300°C, the interdiffusion of Fe and Ge atoms results in a composition change and the epitaxial growth of FeGe in Fe3Si. Low-temperature (<200°C) MBE can realize fully ordered DO3–Fe3Si with highly axial orientation [minimum yield (χmin)=2.2%]. Postannealing above 400°C results in a composition change and the degradation of axial orientation in the off-stoichiometric Fe3Si. The significance of stoichiometry with regard to thermal stability and the interfacial quality of Fe3Si(111)∕Ge(111) hybrid structures was also discussed.
Fabrication of carbon nanotube-based nanodevices using a combination technique of focused ion beam and plasma-enhanced chemical vapor deposition
Authors: Wu J. , Eastman M. , Gutu T. , Wyse M. , Jiao J. , Kim S.-M. , Mann M. , Zhang Y. , Teo K. B. K.
Published: October 2007

This study focuses on the fabrication of two nanodevice prototypes which utilized vertical and horizontal carbon nanotubes used the focused ion beam to localize the catalysts, followed by plasma-enhanced chemical vapor deposition. First, metal-gated carbon nanotube field emitter arrays were fabricated on multilayer substrates containing an imbedded catalyst layer. Second, horizontally aligned single-walled carbon nanotubes were grown on a transmission electron microscopy grid. This allows the carbon nanotubes to be directly analyzed in a transmission electron microscope. It is expected that the methodology introduced here will open up opportunities for the direct fabrication of carbon nanotube based nanodevices.
Giant suppression of Auger electron cooling in charged nanocrystals
Authors: Califano Marco
Published: October 2007

This letter presents a detailed study of the electron relaxation lifetimes from the excited p-like state into the ground s-like state via Auger cooling in positively and negatively charged CdSe nanocrystals, where the dependence of Auger cooling rates on size, temperature, and carrier-carrier interaction effects is investigated. A nearly two-orders-of-magnitude reduction of Auger rates is found in small nanocrystals populated by two electrons and one hole at room temperature. This effect increases with decreasing temperature leading to a total lifetime increase of up to four orders of magnitude for T∼10K. Such a giant suppression of Auger cooling rates appears to be a general property of semiconductor nanocrystals. A similar reduction of Auger rates at room temperature is found in negatively charged PbSe nanocrystals as well.
Features of ion acceleration by circularly polarized laser pulses
Authors: Liseikina T. V. , Macchi A.
Published: October 2007

The characteristics of a MeV ion source driven by superintense, ultrashort laser pulses with circular polarization are studied by means of particle-in-cell simulations. Predicted features include high efficiency, large ion density, low divergence, and the possibility of femtosecond duration. A comparison with the case of linearly polarized pulses is made.
A volume-memory liquid
Authors: Han A. , Qiao Y.
Published: October 2007

By dispersing nanoporous particles in an electrolyte solution, a “milklike” suspension is formed. At a low temperature, the nanoporous phase is hydrophilic, and thus the liquid can fill the nanopores spontaneously. As the temperature increases, the nanopore surfaces become hydrophobic. Consequently, the confined liquid defiltrates, leading to a significant system expansion. As the suspension works in between two different temperatures, it behaves as a thermal machine, exhibiting a volume-memory characteristic. Due to the large surface area, its energy density and the deformability are much higher than that of conventional shape-memory solids.
Common origin of ferromagnetism and band edge Zeeman splitting in GaMnAs at low Mn concentrations
Authors: Chakarvorty R. , Shen S. , Yee K. J. , Wojtowicz T. , Jakiela R. , Barcz A. , Liu X. , Furdyna J. K. , Dobrowolska M.
Published: October 2007

We report magnetic circular dichroism measurements on thin GaMnAs films with low Mn concentration, which reveal that exchange-induced spin splitting of the band edges occurs only in samples that show ferromagnetic order, and is not observed in paramagnetic samples. These results lead to the conclusion that Mn ions in the A0 configuration (d5+hole) provide the only mechanism for exchange interaction between Mn spins and band carriers. We also show that there is a linear relation between the observed exchange-induced splitting of the band edges and the Curie temperature, pointing to a common origin of the band edge splitting and ferromagnetism in GaMnAs.