bluuebunny/crossref_metadata_2025 huggingface dataset:
De-industrialization and re-industrialization: women's employment and the changing character of Colchester, 1700–1850
Authors: Sharpe Pamela
Published: February 2009

The relationship between changes in the local economy of the town and region of Colchester are explored in relation to women's employment opportunities. Economic decline and technological change in the woollen industry, as well as diminishing agricultural work for females, provided a ‘push’ factor for women to move to Colchester. In the town, urban rejuvenation meant expansion in the service sector. Yet Colchester was unable to absorb all the labouring women who moved there. Employers introduced new types of industry, characteristically by expanding from retailing to manufacture. The sweated trades produced silk, shoes and ready-made clothes. A process of re-industrialization was, then, engendered by the availability of cheap female labour.
A charitable indulgence: street stalls and the transformation of public space in Melbourne,c. 1850–1920
Authors: Brown-May Andrew
Published: February 2009

The automobile is often misconstrued as being exclusively responsible for the decline of traditional street culture. This paper argues that the marginalisation of street vendors may also be related to developing definitions of the street as the locus of respectability, unobstructed circulation, nationalism and civic pride. Street entrepreneurs of the 1850s became urban nuisances by the 1900s, associated more with obstruction and underservedness as with convenience and enterprise. Licensing records of bootblacks and coffee-stall keepers as objects of municipal benevolence reveal their economic and social roles in the micro-geography of the city. While nostalgia can distort the realities of historical and contemporary public spaces, the street evacuated of social density and diversity is one of the great losses of modern urban life.
Eugenics and public health in Britain, 1900–40: scenes from provincial life
Authors: Welshman John
Published: February 2009

Historians have attempted to assess the impact of eugenics on public health provision in a number of fields including mental health, birth control, voluntary sterilization and housing. However, most of this work has concentrated on debates at the national level, and we know much less about the ways in which eugenics may have helped shape health services in provincial cities. It has been suggested that Leicester was a city in which eugenicists were particularly prominent, and this article examines the impact of eugenics on three aspects of public health between 1900 and 1940; mental health, birth control and housing. It concludes that while eugenics did have a practical outcome in mental health and birth control, its influence on housing policy was more elusive, and 1935 marked a turning-point after which eugenics was less significant in health policy and intellectual life.
Assessed taxes as sources for the study of urban wealth: Bristol in the later eighteenth century
Authors: Baigent Elizabeth
Published: February 2009

Little is known of the value of eighteenth-century rates and taxes as sources for the urban historian. Corfield, in her study of eighteenth-century Norwich, stated in 1976 that ‘the stereotyped nature of eighteenth-century tax assessments precludes use of fiscal data from national sources’ and this is a fair reflection of the then and to some extent the current orthodoxy, despite Rudé's pioneering studies of the 1960s in which he used land tax and poor rate returns to estimate the wealth of the electorate of Hanoverian London and Middlesex. Schwarz, in a study of late-eighteenth-century London, could still comment in 1979 that for eighteenth-century rates and taxes ‘little is known beyond general impressions’. Recently, however, Wright has thrown interesting light on the use of the Easter books and poor rates of early-modern towns and cities, and the 1986 volume on the land tax edited by Turner and Mills, although still largely concerned with the use of rural land tax assessments, includes three chapters on the value of the assessments in urban and industrial history. The writers hope that city rate and national tax returns might play a fuller role as historical sources, but their optimism is tempered with caution because of the returns' intractability and inconsistency. It is hoped here to reinforce both their enthusiasm and their caution, to reveal additional pitfalls and suggest ways to avoid them and in particular to extend the debate to the neglected pre-1780 assessments and to the city of Bristol.
Property transfers and the Register of Sasines: urban development in Scotland since 1617
Authors: Rodger Richard , Newman Jennifer
Published: February 2009

Walter Scott's assertion inRob Roythat ‘In those days possession was considerably more than eleven points of the law’ overlooked a pivotal point of Scots Law, the distinction between ownership and possession. Possession or occupancy was not ‘as good as title’ as the sixteenth-century Scottish proverb or old French saying ‘possession vaut titre’ claimed. Though the distinction between ownership and possession might have seemed a nicety to Rob Roy in the sixteenth century, by 1617 a general register of titles to land, the Register of Sasines, was established in Scotland, and has continued virtually uninterrupted until the present day. It is consequently a record of immense importance to urban historians.
Lower incidence of procoagulant abnormalities during follow-up after creation of the Fontan circulation in children
Authors: Rask Olof , Hanséus Katarina , Ljung Rolf , Strandberg Karin , Berntorp Erik
Published: February 2009

Objective

Children who undergo surgery for complex congenital cardiac disease are reported to be at increased thrombotic risk. Our aim was to evaluate long-term changes in the haemostatic system after surgery, to compare markers of activated coagulation in children having surgery with those in a healthy control population, and to relate them to adverse clinical outcome.

Patients and methods

We studied, prior to surgery, the coagulation profiles of a cohort of 28 children admitted for a modified Fontan operation, studying them again after a period of mean follow-up of 9.6 years. Median age at the time of final surgery was 18.5 months, with a range from 12 to 76 months. We compared generation of thrombin, and levels of the activated protein C-protein C inhibitor complex to controls at follow-up. Thrombophilia and clinical outcome were evaluated.

Results

At long-term follow-up, a lower incidence of procoagulant abnormalities was observed compared to that before surgery. Of 27 patients, 3 (11%), but none of 45 controls, had levels of activated protein C-protein C inhibitor complex above the reference range. There were no significant differences in generation of thrombin between patients and controls. No thrombotic events were recorded, and the patients were generally in good clinical condition.

Conclusions

Overall, haemostasis appeared to be in balance, and less prothrombotic, after surgery. A subset of the cohort did show indications of activated coagulation. The current therapeutic approach seems to be sufficient to protect the majority of patient. New tests of global coagulation, nonetheless, may be helpful in improving identification of individuals at increased thrombotic risk.
Collective responsibility and the state
Authors: Parrish John M.
Published: February 2009

This article considers the question of whether and to what degree citizens are responsible collectively for the actions of their state. In contrast to current accounts of collective responsibility, which focus on causality or affect as means for transmitting responsibility, the article develops an alternative account, the ‘authorized state’ model. This model, drawn from core intuitions of the social contract tradition, sees collective responsibility as being transmitted through the state as the agent or representative of its citizens. Having developed this model as an ideal type, the article then assesses under what circumstances the model is most applicable. The article finally applies the model to the US war in Iraq to assess the collective responsibility of US citizens for the outcomes of that war.
Transnational corporations in ‘bad states’: human rights duties, legitimate authority and the rule of law in international political theory
Authors: Karp David Jason
Published: February 2009

From an international political theory perspective, this paper assesses the justifiability of ascribing human rights obligations, in the form of international or extraterritorial law, onto transnational corporations (TNCs). The major policy prescriptions in favour of extending human rights duties to include TNCs become deeply problematic when considered in light of advocates’ claims that human rights rules, rather than a sovereign’s legal rules, are necessarily the rules that are truly authoritative and/or in line with a ‘global rule of law’. This paper discusses concepts such as authority, human rights and the rule of law, and juxtaposes these concepts: firstly, with one another; secondly, with the legalstatus quoabout jurisdiction over companies; and thirdly, with corporations’de factotransnationality in the contemporary international system. This paper discusses key similarities and differences between companies, states, and individuals, and highlights the relevance of these distinctions to those agents’ potential human rights duties. This paper concludes by arguing that the ‘TNC and human rights’ project is well worth pursuing, but according to different theoretical foundations than those currently endorsed by legal and policy analysts, and it suggests important directions for future research.
Perceptual Load Improves the Expression but not Learning of Relevant Sequence Information
Authors: Deroost Natacha , Coomans Daphné , Soetens Eric
Published: February 2009

In two experiments, we investigated the hypothesis of Rowland and Shanks (2006a) that sequence learning of relevant information is resistant to variations in perceptual load. Under conditions of increased selection difficulty, participants incidentally learned a sequence of targets presented together with three distractors. Target and distractors were composed of pairs of letters and shared more or less features with each other, rendering perceptual identification of the target either more (high load) or less (low load) attention demanding. The expression of sequence learning improved significantly under high load conditions as compared to low load conditions. This could indicate that the cognitive system promotes the development of response-based sequence learning in order to cope with the attentional demands arising from high perceptual load. However, the learning process proved to be unaffected by perceptual load when tested under baseline conditions without distractors (Experiment 1) or under opposite load conditions as during training (Experiment 2). This demonstrates that sequence learning is not influenced by increasing selection demands and suggests that sequence learning runs independently of input attention.
Millennial‐scale northwest African droughts related to Heinrich events and Dansgaard‐Oeschger cycles: Evidence in marine sediments from offshore Senegal
Authors: Itambi A. C. , von Dobeneck T. , Mulitza S. , Bickert T. , Heslop D.
Published: February 2009

We present a suite of new high‐resolution records (0–135 ka) representing pulses of aeolian, fluvial, and biogenic sedimentation along the Senegalese continental margin. A multiproxy approach based on rock magnetic, element, and color data was applied on three cores enclosing the present‐day northern limit of the ITCZ. A strong episodic aeolian contribution driven by stronger winds and dry conditions and characterized by high hematite and goethite input was revealed north of 13°N. These millennial‐scale dust fluxes are synchronous with North Atlantic Heinrich stadials. Fluvial clay input driven by the West African monsoon predominates at 12°N and varies at Dansgaard‐Oeschger time scales while marine productivity is strongly enhanced during the African humid periods and marine isotope stage 5. From latitudinal signal variations, we deduce that the last glacial ITCZ summer position was located between core positions at 12°26′ and 13°40′N. Furthermore, this work also shows that submillennial periods of aridity over northwest Africa occurred more frequently and farther south than previously thought.
An exploratory analysis of error components in hydrological regression modeling
Authors: Kjeldsen Thomas R. , Jones David A.
Published: February 2009

The use of the generalized least squares (GLS) technique for estimation of hydrological regression models has become good practice in hydrology. Through a regression model, a simple link between a particular hydrological variable and a set of catchment descriptors can be established. The regression residuals can be treated as the sum of sampling errors in the hydrological variable and errors in the regression model. This article presents a method for exploring and developing a parameterized form for the cross‐correlation between the regression model errors. Given an initial GLS analysis, a reweighted set of regression residuals is defined such that the covariance of these residuals is essentially similar to that of the model errors. The cross‐products of the reweighted regression residuals, pooled within bins, are then used to identify a structure and to fit a parameterized form for the cross‐correlations of the regression errors. These estimated cross‐correlations are then used to inform improved GLS and reweighting steps, leading to a recursive procedure. The main advantage of the recursive GLS procedure is that it allows for a simple demonstration of the actual existence of model error correlation as well as for exploring suitable models for the correlation. However, while the procedure for identifying a parametric description for the model error correlation is reasonable, estimation of the parameters within the recursive procedure is affected by the data‐binning step. Thus it is suggested that once a structure for the correlation has been decided, further data analysis—such as final decisions about variables included in the regression model and final estimation of parameters—should be undertaken within a maximum likelihood framework. The procedure has been tested on annual maximum flow data from 602 catchments located throughout the United Kingdom. A set of Monte Carlo experiments further confirmed the ability of the recursive GLS procedure to correctly identify and estimate the true model error correlation.
Effect of solar variability on atmospheric moisture storage
Authors: Wasko Conrad , Sharma Ashish
Published: February 2009

The 11‐year solar cycle is used as the basis of imparting variability in solar forcing in a General Circulation Model. Using different amplitude solar forcing it was found that the resulting global atmospheric moisture content exhibited a high power in its wavelet spectrum at the 11‐year frequency. To identify long term climatic trends, the Earth's atmosphere was conceptualized as a storage reservoir filling and depleting the atmospheric moisture with time. A high required storage implied that the climate of that region exhibits larger climate variations leading to a larger moisture scarcity or drought. It was found that regions that had relatively small storage requirements experienced an increase in storage required due to the 11‐year solar cycle, while regions with relatively large storage requirements experiencing a decrease in storage. It is concluded that the 11‐year solar cycle may act to reduce sustained variations in moisture availability across significant climatic regions.
Tropospheric O3 from photolysis of O2
Authors: Prather Michael J.
Published: February 2009

Photolytic dissociation of molecular oxygen (O2) at wavelengths about 205 nm produces ozone (O3) in the upper tropical troposphere. In tropospheric chemistry models that ignore this process, the O3 abundance above 14 km in the tropics (a.k.a. Tropopause Transition Layer) is underestimated by 5 to 20 ppb. Even for models including O2 photolysis, uncertainty in the O2 cross sections yields similar uncertainty in TTL O3. The related impact on global atmospheric chemistry is small, i.e., ±0.2% in CO and CH4 budgets, but the change in the O3 column, ±1.6 DU in the tropics, may be important in calculating heating rates and climate forcing.
Regulation of human myoblast differentiation by PEBP4
Authors: Garcia Reynaldo , Grindlay Joan , Rath Oliver , Fee Frances , Kolch Walter
Published: February 2009

The RAF–MEK–ERK pathway regulates both myoblast proliferation and differentiation; however, it is unclear how these events are coordinated. Here, we show that human phosphatidylethanolamine‐binding protein 4 (PEBP4), a RAF kinase inhibitory protein (RKIP) family protein expressed preferentially in muscle, regulates the activity of the ERK pathway and myoblast differentiation by acting as a scaffold protein. In contrast to RKIP, which disrupts the RAF1–MEK interaction, PEBP4 forms ternary complexes with RAF1 and MEK, and can scaffold this interaction. PEBP4 expression is induced during the differentiation of primary human myoblasts. Consistent with the properties of a scaffold, PEBP4 enhances the RAF1–MEK interaction and the activation of MEK at low expression levels, whereas it inhibits these parameters at higher expression levels. Downregulation of PEBP4 by short hairpin RNA in human myoblasts increases MEK signalling and inhibits differentiation; by contrast, PEBP4 overexpression enhances differentiation. Thus, PEBP4 participates in the control of muscle cell differentiation by modulating the activity of MEK and ERK.
Speech Motor Control and Predicting Disordered Speech
Authors: Leeper H.A.
Published: February 2009

There are numerous theories of speech production that focus on motor control for regulation of speech output. One of the more prominent is the “pressure regulation-control” model that was developed from studies of the aerodynamic speech activities of normal speakers and individuals with cleft lip and palate and accompanying resonance and speech disorders. This theory aid in understanding the nature of maladaptive speech production related to velopharyngeal inadequacy (VPI). Descriptions of experimental research will be employed to relate this theory to effective strategies of speech management for individuals with VPI.
Lenard scheme for two-dimensional periodic Volterra chain
Authors: Wang Jing Ping
Published: February 2009

We prove that for compatible weakly nonlocal Hamiltonian and symplectic operators, hierarchies of infinitely many commuting local symmetries and conservation laws can be generated under some easily verified conditions no matter whether the generating Nijenhuis operators are weakly nonlocal or not. We construct a recursion operator of the two-dimensional periodic Volterra chain from its Lax representation and prove that it is a Nijenhuis operator. Furthermore we show that this system is a (generalized) bi-Hamiltonian system. Rather surprisingly, the product of its weakly nonlocal Hamiltonian and symplectic operators gives rise to the square of the recursion operator.
Effect of Al and Sb doping on the magnetic properties of ZnMnO and ZnCoO
Authors: Sharma V. K. , Varma G. D.
Published: February 2009

The bulk polycrystalline samples with nominal compositions Zn0.98−y(Mn∕Co)0.02(Al∕Sb)yO (y=0, 0.01, and 0.03) have been synthesized via solid state reaction route. The x-ray diffraction results reveal the presence of mainly wurtzite structure of pure ZnO in all the Al∕Sb codoped ZnMnO and ZnCoO samples. EDAX results confirm the presence of all elements in the samples in the stoichiometric ratio. While the Zn(Mn∕Co)O samples show paramagnetic behavior at room temperature, the Al∕Sb codoped ZnMnO samples exhibit room temperature ferromagnetism (RTFM) with saturation magnetization (Ms). The M-H curves of Al∕Sb codoped ZnCoO samples show almost linear variation with a small kink at the origin, indicating the presence of weak ferromagnetism in the Al∕Sb codoped ZnCoO samples. Possible mechanisms of the observed RTFM in Al∕Sb codoped Zn(Mn∕Co)O samples are discussed in this paper.
Effect of a forming field on the magnetic and structural properties of thin Fe–Ga films
Authors: Morley N. A. , Javed A. , Gibbs M. R. J.
Published: February 2009

The structural, magnetic, and magnetostrictive properties of 75nm Fe100−xGax films (0⩽x⩽30) have been studied to determine how a forming field during growth affects these properties. Two film sets were grown using a cosputtering-evaporation technique with and without a forming field of 65kAm−1. Using x-ray diffraction, the texture, lattice parameter, and the grain size were determined. An out-of-plane ⟨110⟩ texture was found for all films. The magnetization loops were measured on a magneto-optic Kerr effect magnetometer, from which the anisotropy symmetry was inferred from the remanent magnetization. It was found that the forming field produced a pronounced uniaxial anisotropy. The effective magnetostriction constant was measured using the Villari effect. The effective magnetostriction constant was compared with that calculated for a polycrystalline film with ⟨110⟩ out-of-plane texture using bulk constants, and the results are discussed.
Complex conductivity of UTX compounds in high magnetic fields
Authors: Alsmadi A. M. , Alyones S. , Mielke C. H. , McDonald R. D. , Zapf V. , Altarawneh M. M. , Lacerda A. , Chang S. , Adak S. , Kothapalli K. , Nakotte H.
Published: February 2009

We have performed rf-skin depth (complex-conductivity) and magnetoresistance measurements of antiferromagnetic UTX compounds (T=Ni and X=Al, Ga, Ge) in applied magnetic fields up to 60 T applied parallel to the easy directions. The rf penetration depth was measured by coupling the sample to the inductive element of a resonant tank circuit and then, measuring the shifts in the resonant frequency Δf of the circuit. Shifts in the resonant frequency Δf are known to be proportional to the skin depth of the sample and we find a direct correspondence between the features in Δf and magnetoresistance. Several first-order metamagnetic transitions, which are accompanied by a drastic change in Δf, were observed in these compounds. In general, the complex-conductivity results are consistent with magnetoresistance data.
Spin polarized transport in an asymmetric ferromagnetic/quantum dot/ferromagnetic system
Authors: Ma M. J. , Jalil M. B. A. , Tan S. G.
Published: February 2009

We investigate the tunnel magnetoresistance (TMR) of the double barrier magnetic tunnel junction, where a quantum dot (QD) with discrete electron and hole energy levels is sandwiched between ferromagnetic leads. The effects of the symmetry of the coupling between the leads and the dot on both the TMR and spin accumulation (SA) are studied for voltage ranges corresponding to the QD’s single and double occupancies. When the QD is singly occupied, both the TMR and SA assume at their minimum values for symmetrical junctions with identical coupling strengths. For the doubly occupied QD, the opposite occurs with the highest TMR and SA being observed for symmetrical junctions with identical coupling strengths. The TMR is found to be strongly correlated with the spin accumulation in the QD.
Size-dependent strain relaxation in InN islands grown on GaN by metalorganic chemical vapor deposition
Authors: Tsai Wen-Che , Lin Feng-Yi , Ke Wen-Cheng , Lu Shu-Kai , Cheng Shun-Jen , Chou Wu-Ching , Chen Wei-Kuo , Lee Ming-Chih , Chang Wen-Hao
Published: February 2009

We report Raman measurements on InN islands grown on GaN by metalorganic chemical vapor deposition. The Raman frequency of the InN E2 mode is found to decrease exponentially with the island’s aspect ratio, indicating a size dependent strain relaxation during the island formation. Our results suggest that most of the strain at the InN–GaN interface have been released plastically during the initial stage of island formations. After that, the residual strain of only −3.5×10−3 is further relaxed elastically via surface islanding. The experimental data are in agreement with the strain relaxation predicted from a simplified model analysis as well as three-dimensional finite-element simulations.
Amplification of magnetoresistance and Hall effect of Fe3O4–SiO2–Si structure
Authors: Wang Xianjie , Sui Yu , Tang Jinke , Li Yao , Zhang Xingquan , Wang Cong , Liu Zhiguo , Su Wenhui
Published: February 2009

In this paper, we report the magnetoresistance and the Hall effect in the Fe3O4–SiO2–Si structure. Single phase magnetite films were deposited on n-type silicon substrates using laser molecular beam epitaxy. When the temperature is increased beyond 230 K, the resistance drops rapidly because the conduction path starts to switch from the Fe3O4 film to the inversion layer underneath the native SiO2 via thermally assisted tunneling. A large negative magnetoresistance is observed at about 230 K, and this maximum shifts to higher temperature with increasing film thickness. Hall effect data of the structure show that the carriers are holes above the channel switching temperature. Our results confirm that the large magnetoresistance at ∼230 K originates from the amplification of the magnetoresistance of the magnetite in the Fe3O4–SiO2–Si structure.
Coercive field and energy barriers in partially disordered FePt nanoparticles
Authors: Aranda G. R. , Chubykalo-Fesenko O. , Yanes R. , González J. , del Val J. J. , Chantrell R. W. , Takahashi Y. K. , Hono K.
Published: February 2009

Partially disordered FePt nanoparticles prepared by the sputtering method and protected by Al2O3 constitute an interesting realization of graded media, recently suggested for future generations of magnetic recording. By depositing the alumina layer, the particle is partially disordered with gradually varying properties. The current work comprises a comparison between experimental data and atomistic modeling results of the coercive field and energy barriers in FePt particles with gradually spatially varying properties, specifically the magnetization, anisotropy, and exchange constants. From our modeling we conclude that the magnetization reversal processes for dynamic reversal at the coercive field and for the zero field energy barrier involve different reversal modes. The coercive field decreases as a function of disordering length up to 2 T and is in good agreement with measured values. The zero field energy barrier, except for highly disordered particles, is almost independent of the disordering length, retaining the high values required for thermal stability.
Atomically smooth and single crystalline Ge(111)/cubic-Pr2O3(111)/Si(111) heterostructures: Structural and chemical composition study
Authors: Giussani A. , Rodenbach P. , Zaumseil P. , Dabrowski J. , Kurps R. , Weidner G. , Müssig H.-J. , Storck P. , Wollschläger J. , Schroeder T.
Published: February 2009

Engineered wafer systems are an important materials science approach to achieve the global integration of single crystalline Ge layers on the Si platform. Here, we report the formation of single crystalline, fully relaxed Ge(111) films by molecular beam epitaxial overgrowth of cubic Pr oxide buffers on Si(111) substrates. Reflection high-energy electron diffraction, scanning electron microscopy, and x-ray reflectivity show that the Ge epilayer is closed, flat, and has a sharp interface with the underlying oxide template. Synchrotron radiation grazing incidence x-ray diffraction and transmission electron microscopy reveal the type-A/B/A epitaxial relationship of the Ge(111)/cubic Pr2O3(111)/Si(111) heterostructure, a result also corroborated by theoretical ab initio structure calculations. Secondary ion mass spectroscopy confirms the absence of Pr and Si impurities in the Ge(111) epilayer, even after an annealing at 825 °C.
Activation of ion implanted Si in GaN using a dual AlN annealing cap
Authors: Hager C. E. , Jones K. A. , Derenge M. A. , Zheleva T. S.
Published: February 2009

A dual annealing cap composed of a thin, low temperature metal-organic chemical vapor deposition (MOCVD) deposited AlN adhesion layer and a thicker, sputtered AlN film for added mechanical strength enabled us to anneal Si-implanted layers for 30 min at temperatures up to 1250 °C. At higher temperatures the cap was destroyed by the large partial pressure of the N2 from the GaN, which exceeds the yield strength of AlN. Electrical activations as high as 70% and electron mobilities comparable to those of in situ doped films were achieved. Compared to other methods, the surfaces are better protected using this cap because it adheres better than sputtered AlN, SiO2, or Si3N4; does not crack like MOCVD grown AlN films deposited at normal temperatures (∼1100 °C); and is stronger than thin MOCVD grown AlN films deposited at low temperatures (∼600 °C). Even though N does not escape, and in so doing, forms thermal etch pits, the surface of the annealed GaN is roughened by solid state diffusion with the surface roughness increasing with the annealing temperature.
Magnetic anisotropy of Co2MnSn1−xSbx thin films grown on GaAs (001)
Authors: Paudel Moti R. , Wolfe Christopher S. , Patton Heather M. A. , Simonson Jeff , Dubenko Igor , Ali Naushad , Stadler Shane
Published: February 2009

Heusler alloy Co2MnSn1−xSbx (x=0.0, 0.5, and 1.0) thin films were grown on GaAs (001) substrates using pulsed laser deposition techniques. Growth parameters have been determined that result in highly magnetically anisotropic, crystalline, and oriented (001) films. The angular dependences, relative to the GaAs (001) crystallographic directions, of the coercive field Hc(θ) and the remanence Mr(θ) were determined from angle dependent magneto-optic Kerr effect (MOKE) measurements. It was found that Hc(θ) revealed higher order symmetry contributions to the magnetic anisotropy than did Mr(θ). The Fourier analysis of rotational MOKE data was used to determine the symmetry contributions to the total anisotropy.
Synthetic antiferromagnetic nanoparticles with tunable susceptibilities
Authors: Hu Wei , Wilson Robert J. , Earhart Christopher M. , Koh Ai Leen , Sinclair Robert , Wang Shan X.
Published: February 2009

High-moment monodisperse disk-shaped Co–Fe magnetic nanoparticles, stable in aqueous solution, were physically fabricated by using nanoimprinted templates and vacuum deposition techniques. These multilayer synthetic antiferromagnetic nanoparticles exhibit nearly zero magnetic remanence and coercivity, and susceptibilities which can be tuned by exploiting interlayer magnetic interactions. In addition, a low cost method of scaling up the production of sub-100 nm synthetic antiferromagnetic nanoparticles is demonstrated.
Structures, inversion barriers, and parity violation effects in chiral SeOXY molecules (X,Y=H, F, Cl, Br, or I)
Authors: Figgen Detlev , Schwerdtfeger Peter
Published: February 2009

Parity violation (PV) effects for a series of chiral molecules of the type SeOXY (X,Y=H, F, Cl, Br, or I) are predicted from four-component relativistic Hartree–Fock and density functional theory. All optimized SeOXY structures are nonplanar with large inversion barriers ranging from 23 to 55 kcal/mol; thus, all SeOXY molecules remain enantiomeric stable on the laboratory time scale. The variation in PV between the different methods applied is small enough for each molecule to allow for an accurate prediction of these effects. At the respective equilibrium geometries the enantiomers exhibit parity violating energy shifts of up to 17 Hz. The Se–O stretching mode of all investigated SeOXY molecules lies in the experimentally favorable CO2 laser range of ∼1000 cm−1. We therefore investigated PV effects in vibrational transitions along a single normal mode using Dirac–Kohn–Sham theory. The PV energy differences in the fundamental Se–O stretching mode amount up to 110 mHz (largest for SeOClI) and are larger compared to the C–F stretching mode of CHFBrI previously investigated. Hence these SeOXY molecules are ideal candidates for the future experimental gas-phase detection of PV in vibrational spectra of chiral molecules.
Optical limiting for microsecond pulses
Authors: Gavrilyuk Sergey , Liu Ji-Cai , Kamada Kenji , Ågren Hans , Gel’mukhanov Faris
Published: February 2009

We present a dynamical theory of nonlinear absorption and propagation of laser pulses with duration in the microsecond time domain. The general theory is applied to fullerene C60 because of its good optical limiting properties, namely, a rather low ground state absorption and a strong triplet-triplet absorption. It is shown that sequential absorption involving strong triplet-triplet transitions is the major mechanism of nonlinear absorption. The intrinsic hierarchy of time scales makes an adiabatic solution of the coupled rate equations valid, which therefore can be reduced to a single dynamical equation for the ground state population. The slow evolution of this population is defined by an effective rate of population transfer to the triplet state and by the pulse duration. The propagation effect plays an important role in the optical power limiting performance. The intensity of the field as well as the population of the triplet state decreases during the pulse propagation, and a weakened nonlinear sequential two-photon absorption is followed by a linear one-photon absorption which gradually becomes the dominating process. The competition between these qualitatively different processes depends on the field intensity, the length of the absorber, and the concentration. The pulse propagation is studied by solving numerically the two-dimensional paraxial field equation together with the effective rate equation for the ground state population.
Regular stepped structures on clean Si(hhm)7×7 surfaces
Authors: Chaika A. N. , Fokin D. A. , Bozhko S. I. , Ionov A. M. , Debontridder F. , Dubost V. , Cren T. , Roditchev D.
Published: February 2009

Regular single and triple step arrays with different periodicities have been fabricated in ultrahigh vacuum on clean Si(557) surfaces at various thermal treatment procedures. The atomic structure of the triple step staircases has been studied with high resolution scanning tunneling microscopy (STM). The results of atomically resolved STM experiments demonstrate a number of possible triple step configurations on Si(hhm) surfaces. The triple step models consistent with atomically resolved STM data obtained on regular Si(223) and Si(556) triple step staircases are presented. Possible driving forces for self-assembling regular step arrays on large scale areas are discussed.
On the role of perpendicular electron collisions in drift and acoustic wave instabilities
Authors: Vranjes J. , Poedts S.
Published: February 2009

Perpendicular electron dynamics and the associated collisions are discussed in relation to the collisional drift wave instability. In addition, the limit of small parallel wave numbers of this instability is studied and it is shown to yield a reduced wave frequency. It is also shown that in this case the growth rate in fact decreases for smaller parallel wave numbers, instead of growing proportional to 1∕kz2. As a result, the growth rate appears to be angle dependent and to reach a maximum for some specific direction of propagation. The explanation for this strange behavior is given. A similar analysis is performed for acoustic perturbations in plasmas with unmagnetized ions and magnetized electrons, in the presence of a density gradient.
Electrical depth profiling in thin SiON layers
Authors: Rozenblat A. , Rosenwaks Y. , Segev L. , Cohen H.
Published: February 2009

The internal structure of SiON films is extracted electrically, demonstrating an efficient, noncontact, nondestructive means for depth compositional analysis in gate oxides. The electrical data, obtained using x-ray photoelectron spectroscopy (XPS) based controlled surface charging (CSC), are compared with independent time of flight secondary ion mass spectroscopy and angle resolved XPS data. Inhomogeneous composition with significant nitrogen enrichment at the top of the oxide layer is observed. Capabilities of the CSC method in treating heterostructures of poor chemical contrast are discussed.
Formation of nanocrystalline films of Sr2FeMoO6 on Si(100) by pulsed laser deposition: Observation of preferential oriented growth
Authors: Jalili Helia , Heinig Nina F. , Leung K. T.
Published: February 2009

Nanocrystalline Sr2FeMoO6 films have been grown on a Si(100) substrate by pulsed laser deposition under different growth conditions including deposition temperature and time. A nanocrystalline single-phase Sr2FeMoO6 film was obtained at a temperature as low as 600 °C. This high-quality ferromagnetic film was found to have a saturation magnetic moment of 3.4μB per formula unit and a coercive field of 1.5 kOe at 77 K with micrometer-sized magnetic domains. By using glancing-incidence x-ray diffraction with different incident beam angles, the crystal structure of the film was sampled as a function of depth. For the as-grown Sr2FeMoO6 films thicker than 60 nm, a preferential orientation of the nanocrystals in the film was observed, despite the lack of good lattice matching with the Si substrate. At a higher deposition temperature of 800 °C, the as-grown film exhibited the same saturation magnetic moment but with a discernibly lower coercive field of 0.8 kOe, consistent with the larger grain size obtained at a higher growth temperature.
Resistive switching properties in oxygen-deficient Pr0.7Ca0.3MnO3 junctions with active Al top electrodes
Authors: Li Song-Lin , Shang D. S. , Li J. , Gang J. L. , Zheng D. N.
Published: February 2009

Current-voltage characteristics, conduction mechanisms, and resistive switching properties are investigated in Al/Pr0.7Ca0.3MnO3 (PCMO)/Pt junctions. The junction resistance exhibits an irreversible increase from 2 to 90 MΩ in the forming process, the first several repeated bias sweeps. In contrast to the PCMO junctions involving inert top electrode (TE), the active Al-TE-based junctions show very large junction resistance and opposite cycling directions. It is found that the junction resistance sequence is qualitatively consistent with the standard Gibbs energies ΔG0 for the formation of corresponding TE oxides, rather than the Schottky barrier heights. Current-voltage fits indicate that the conduction processes in high and low resistance states are controlled by Poole–Frenkel emission and space-charge-limited conduction, respectively. The junctions show asymmetric switching thresholds with the minimal switching voltages are +1 V at the positive and −4 V at the negative side. Resistance retention tests indicate that the low resistance state is unstable and it gradually relaxes to higher resistance values. All the properties are discussed by the oxidation/reduction reaction at the Al/PCMO interface.
Hydrogen complexes in Zn deficient ZnO
Authors: Karazhanov S. Zh. , Marstein E. S. , Holt A.
Published: February 2009

This work presents a study of H complexes in Zn deficient ZnO by density functional calculations. It is found that the location of two H atoms at the Zn vacancy (VZn) is energetically more preferable than the distant H and VZn. Each of the two H atoms saturates one dangling O bond by forming an O–H bond. The resulting defect can be considered to be a 2(O–H)-VZn complex. Since there are four O dangling bonds at the VZn, the site can host four H atoms. It is shown that VZn with four H atoms is energetically more preferable than distant H and VZn. Depending on the number of H atoms at the VZn, the influence of the H-VZn system on the electronic structure of Zn deficient ZnO can be qualitatively different. VZn without a H is a double acceptor and VZn containing one H, i.e., 1(O–H)-VZn complex, is a single acceptor. In ZnO with 2(O–H)-VZn complexes the Fermi level is located at the top of the valence band. A donor level is formed by the 3(O–H)-VZn and 4(O–H)-VZn complexes. Two of the H atoms in 2(O–H)-VZn, 3(O–H)-VZn, and 4(O–H)-VZn complexes do not contribute to free carrier concentration and will cause discrepancy in the free electron and H concentrations. The influence of the complexes on the electrical and optical properties of ZnO is discussed.
Frobenius map on local Calabi–Yau manifolds
Authors: Shapiro I.
Published: February 2009

We prove results that, for a certain class of noncompact Calabi–Yau threefolds, relate the Frobenius action on their p-adic cohomology to the Frobenius action on the p-adic cohomology of the corresponding curves. In the Appendix, we describe our interpretation of the Griffiths–Dwork method.
Use of shorted coaxial transmission line for high-power microwave measurement
Authors: Fan Yu-Wei , Zhong Hui-Huang , Shu Ting , Li Zhi-Qiang , Zhou Heng , Zhou Wei-Hong , Luo Ling
Published: February 2009

In order to reduce the effective area of the receiving antenna to receive microwave power in the high electric field regions, a 1.76 GHz shorted coaxial transmission line (SCTL) is investigated numerically and experimentally in this paper. When the frequency is 1.76 GHz, the simulation results show that the general gain and the effective area of the SCTL are −10.21 dBi and 2.19 cm2, respectively, and the power capacity of the SCTL is about 41 kW. So the maximum power flow density, which can be measured by the SCTL, is 18.7 kW/cm2. With the frequency varying from 1.70 to 1.80 GHz, the general gain increases from −11.19 to −9.42 dBi linearly. The general gain of the SCTL is calibrated with the Agilent E8363B network analyzer in an anechoic chamber, and the calibrated results agree with the simulation. The high-power tests are performed on an improved magnetically insulated transmission line oscillator. Compared to the cutoff free-field probe, the maximum power flow density, which can be measured by the SCTL, is higher.
High-performance photorefractive organic glass based on diphenylhydrazone
Authors: Choi Chil-Sung , Moon In Kyu , Kim Nakjoong
Published: February 2009

A multifunctional molecule that possesses photoconductive and electro-optic properties in one molecule was synthesized as a photorefractive organic glass. Diphenylhydrazone as a photoconductive moiety was covalently bound to the enamine derivative as an electro-optic chromophore via a flexible ester link. The sample prepared from a mixture of the multifunctional molecule (99 wt %) and fullerene C60 (1 wt %) showed good photorefractive properties. The 100 μm thick film showed a maximum diffraction efficiency of 69% at a low applied field of 25 V/μm, corresponding to a refractive index modulation (Δn) of 1.50×10−3 and a photoconductivity of 0.46 pS/cm.
Cu-doping effects in CdI2 layered nanostructures: The role of photoinduced electron-phonon anharmonic interactions
Authors: Miah M. Idrish , Kasperczyk J.
Published: February 2009

The Cu-doping effects in CdI2 layered nanocrystals were studied experimentally. We used a photostimulated second harmonic generation (PSHG) in order to investigate the nanoconfined effects. It was found that the PSHG increased with increasing Cu-doping within a low-density limit. For the higher Cu content the PSHG output signal was decreased to the value observed for the undoped CdI2 crystal. The above results suggest that the Cu-metallic clusters play a crucial role in the processes responsible for the observed nonlinear optical effects. The large enhancement of the PSHG observed in the Cu-doped thin nanocrystals confirms the fact that the Cu-impurities of low concentrations favor stronger local photoinduced anharmonic electron-phonon interactions.
Wavelength selection by dielectric-loaded plasmonic components
Authors: Holmgaard Tobias , Chen Zhuo , Bozhevolnyi Sergey I. , Markey Laurent , Dereux Alain , Krasavin Alexey V. , Zayats Anatoly V.
Published: February 2009

Fabrication, characterization, and modeling of waveguide-ring resonators and in-line Bragg gratings for wavelength selection in the telecommunication range are reported utilizing dielectric-loaded surface plasmon-polariton waveguides. The devices were fabricated by depositing subwavelength-sized polymer ridges on a smooth gold film using industrially compatible large-scale UV photolithography. We demonstrate efficient and compact wavelength-selective filters, including waveguide-ring resonators with an insertion loss of ∼2 dB and a footprint of only 150 μm2 featuring narrow bandwidth (∼20 nm) and high contrast (∼13 dB) features in the transmission spectrum. The performance of the components is found in good agreement with the results obtained by full vectorial three-dimensional finite element simulations.
Control of Ge/Si intermixing during Ge island growth
Authors: Leite Marina S. , Kamins T. I. , Medeiros-Ribeiro G.
Published: February 2009

The surface energy and growth kinetics during Ge deposition on Si(001) were modified by growing the films in a phosphine environment. Islands were formed under a H2 flux as well as in a PH3/H2 atmosphere, but the morphologies were different. The presence of PH3 not only affects the island shape and size but also the composition profile. The dramatical inhibition of Ge/Si intermixing during growth leads to islands richer in Ge compared to undoped islands.
A 32.6% efficient lattice-matched dual-junction solar cell working at 1000 suns
Authors: García I. , Rey-Stolle I. , Galiana B. , Algora C.
Published: February 2009

Photovoltaic conversion efficiencies of 32.6% and 30% at concentrations of 1000 and 3500 suns, respectively, are achieved in monolithic GaInP/GaAs dual-junction solar cells grown lattice matched on a GaAs substrate by metal-organic vapor-phase epitaxy. The tunnel-junction design, based on an (Al)GaAs/GaAs heterojunction, is found to be a key factor for achieving this efficiency at such high concentrations. Moreover, the thorough design and joint optimization of the front grid and the top-cell emitter, using quasi-three-dimensional distributed models, also plays a major role. Efficiencies of over 40% at 1000 suns should be achieved by extending this approach to triple-junction devices.
Role of TaON interface for CuxO resistive switching memory based on a combined model
Authors: Zhou P. , Yin M. , Wan H. J. , Lu H. B. , Tang T. A. , Lin Y. Y.
Published: February 2009

For the embedded application of the resistive switching memory using CuxO films, the controllable switching polarity and optimized low resistance state was investigated. Stable bipolar switching behavior was demonstrated for the TaN/CuxO/Cu device. TaON was observed at the anode interface by x-ray photoelectron spectroscopy and transmission electron microscopy, which is believed to play a key role in the resistance transition. The physics behind this phenomenon of reactive top-electrode is revealed. A filament/charges trapped combined model is proposed to clarify the electrical characteristics of the top-electrode/oxide reactions. This observation presents a unique opportunity to elucidate a universal mechanism for the resistive switching of transitional metal oxides.
Frequency narrowing of a 25 W broad area diode laser
Authors: Sell J. F. , Miller W. , Wright D. , Zhdanov B. V. , Knize R. J.
Published: February 2009

We report on the spectral narrowing of a high powered (25 W) broad area diode laser using an external cavity with a holographic diffraction grating. In a Littman–Metcalf configuration, the external cavity is able to reduce the linewidth of the diode laser to primarily a single longitudinal mode (1.8 MHz) for output powers of ≤10 W at 852 nm. Many physics applications could benefit from such high powered, narrow linewidth lasers; however both the frequency stability and the spatial profile of the output beam show room for improvement.