bluuebunny/crossref_metadata_2025 huggingface dataset:
Pharyngeal Branch of the Vagus Nerve Carries Intraepithelial Afferent Fibers in the Cat Pharynx: An Elucidation of the Origin and Central and Peripheral Distribution of these Components
Authors: Miyazaki Junji , Shin Takemoto , Murata Yuzo , Masuko Sadahiko
Published: November 2005

The presence of a sensory component in the pharyngeal branch of the vagus nerve (PhB), including its peripheral distribution and central projection, was studied by denervation and tracer experiments in the cat. The distribution of nerve fibers immunore‐active to protein gene product 9.5, a sensitive neuronal marker; calcitonin gene‐related peptide; and substance P in the pharyngeal epithelium was analyzed in both intact animals and animals subjected to partial denervation by means of sectioning two of the three nerve trunks, the glossopharyngeal nerve, the superior laryngeal nerve, and the PhB, while leaving one intact. The results of this study show that the glossopharyngeal nerve and superior laryngeal nerve carry nerve fibers to the pharyngeal epithelium rostral and caudal to the middle level of the epiglottis, respectively, whereas the PhB carries nerve fibers to the mesopharyngeal epithelium. Tracer experiments, by applying wheat germ agglutinin‐horseradish peroxidase to the PhB, demonstrated retrogradely labeled primary sensory neurons in the jugular ganglion and transganglionic labeling of terminals in the interstitial subnucleus of the nucleus of the tractus solitarius. These results indicate that the PhB contains a sensory component that originates from the jugular ganglion, innervates the mesopharyngeal epithelium, and projects to the nucleus of the tractus solitarius.
PUBLIC ENGAGEMENT WITH SCIENCE? LOCAL UNDERSTANDINGS OF A VACCINE TRIAL IN THE GAMBIA
Authors: FAIRHEAD JAMES , LEACH MELISSA , SMALL MARY
Published: November 2005

This paper considers how parents engage with a large, internationally supported childhood pneumococcal vaccine trial in The Gambia. Current analysis and professional reflection on public engagement is strongly shaped by the imperatives of public health and research institutions, and is thus couched in terms of acceptance and refusal, and ‘informed consent’. In contrast Gambian parents’ perspectives on the trial are couched in conceptual and experiential terms that are linked to their wider dilemmas of raising infants amidst the hazards of globally connected village life. Ethnographic research reveals how for most parents, longer-term experiences of the organization managing the research (the UK Medical Research Council Laboratories in The Gambia) as a health-providing institution override their reflection on trial-specific aims. A decision to participate in the trial involves a perceived balance of benefit and danger – in the extreme, of free medical treatment, versus one’s child being drained of blood for sale to Europe. Social relations (especially gender relations) shape this calculus and study participation. This case suggests how the idea of ‘public engagement with science’ in a globalized context might be recast, with implications for debates in biomedical ethics, and the sustainability of public participation in medical research.
Tracing the Legal Boundary between Empire and Multitude: Wavering with Hardt and Negri (2000–2005)
Authors: LIPPENS RONNIE
Published: November 2005

Since its publication in 2000, Hardt and Negri's book Empire has been at the centre of significant debates within international relations (IR) and international law (IL) communities, both academic and other. Hardt and Negri's recently published Multitude (2004) is likely to add momentum to these debates. Outlining the importance of both Multitude and Empire for legal scholarship and practice, this contribution sets out to give a brief overview of the core issues that are to be distinguished in the debates amongst IR and IL academics, and includes a number of criticisms that could be levelled at Hardt and Negri's work. The focus of the paper, however, is on the ambiguities that mark Hardt and Negri's flawed attempt to deal with the issue of the boundary of Empire and the liminality of (the) multitude. Indeed, this contribution maintains that precisely this rather fundamental flaw in Hardt and Negri's work is why their intellectual ‘tour de force’ is ultimately unconvincing.
The 2005 Budget of the International Criminal Court: Contingency, Insufficient Funding in Key Areas and the Recurring Question of the Independence of the Prosecutor
Authors: O'DONOHUE JONATHAN
Published: November 2005

Faced with increasing expectations and demands on the new International Criminal Court, the process of preparing its budget for 2005 presented significant challenges to the Court, the Committee on Budget and Finance and the Assembly of States Parties. This article focuses on the major challenges and examines the decisions taken by the Assembly. In particular, it looks at budgetary matters relating to the independence of the Prosecutor and decisions that could undermine it. Furthermore, with planned progress towards the first trials it focuses on key areas of the Court's work, including outreach, victim protection and field presence, that are in danger of being compromised through under-investment.
Seasonal variation of barrier layer in the southeastern tropical Indian Ocean
Authors: Qu Tangdong , Meyers Gary
Published: November 2005

The isothermal layer, mixed layer, and barrier layer in the southeastern tropical Indian Ocean are investigated using historical hydrographic and recent Argo‐float profile data. The annual average isothermal and mixed layers are deep (>50 m) near the equator, but they do not have the same topographic structure. The mixed layer is more orientated along the coastline owing to the effect of precipitation and runoff. This forms a thick barrier layer (>25 m) to the west of Sumatra. The thickness decreases to 10 m near eastern Java and less farther to the east and south. The seasonal variation of barrier layer along the equator and off Sumatra/Java is a consequence of interplay between annual and semiannual variations. Surface water convergence, wave propagation, and precipitation are essentially responsible for these variations. Annual (1 cpy) variation is dominant in most of the region studied except for two locations where semiannual variation is also large. The semiannual variation in isothermal depth (ID), mixed layer depth (MLD), and barrier layer thickness (BLT) is most evident along the equator, with a comparable strength to the annual variation. The other region of large semiannual variation in ID and MLD is off Northwest Australia, but no significant variation in BLT is observed there.
Processes controlling the dynamics of compound sand waves in the North Sea, Netherlands
Authors: van Dijk Thaiënne A. G. P. , Kleinhans Maarten G.
Published: November 2005

The understanding of the morphodynamics of harmonic bed forms on the seabed is essential for modeling marine sediment transport and coastal morphologic development. Previous research has mainly focused on the type and distribution of bed forms, but areally extensive data and time series of seabed features are scarce. Multibeam and side‐scan sonar data from four expeditions reveal the contrasts between a coastal site with asymmetric and flattened, three‐dimensional (3‐D) compound sand waves on a shoreface‐connected ridge and an offshore site with asymmetric and sharp‐crested, 2‐D compound sand waves. Migration rates of the coastal sand waves are 6.5–20 m yr−1, while migration rates of the offshore sand waves are −3.6 to 10 m yr−1. This contrasting morphology and dynamic behavior of compound sand waves at the two North Sea sites is explained by differences in the relative importance of tidal currents and wave activity near the bed. These new field data provide parameters and boundary conditions for sand transport models, while the empirically derived behavior of sand waves may be used to validate sand transport and sand wave models.
Effect of sampling time on measured gravel bed load transport rates in a coarse‐bedded stream
Authors: Bunte Kristin , Abt Steven R.
Published: November 2005

This study empirically quantified the effect of sampling time on measured transport rates and fitted rating curves based on results obtained from bed load traps deployed for 2, 10, and 60 min in a coarse‐bedded stream. As expected for a skewed distribution of transport rates, 2 min deployment underpredicted transport rates obtained from 10 and 60 min deployment by factors of 2 and 3 at moderate flows (50–70% Qbkf). At near‐bank‐full flow the underprediction by 2 min versus 10 min sampling increased to a factor of 5, while transport rates collected during 60 min deployments were reduced because of overfilled bags. At flows near incipient gravel motion, 2 min sampling overpredicted transport rates obtained by 10 and 60 min deployment by factors of 2.7 and 3.4. The overprediction is attributed to computational effects arising mainly from the lowest measurable transport rate for each sampling time. Rating curves fitted to transport rates from 2 min sampling were significantly less steep than those for longer deployment times. However, sampling time explains only a small degree of the large difference between rating curves from bed load traps and a Helley‐Smith sampler (2 min sampling).
Magnetic reconnection within rolled‐up MHD‐scale Kelvin‐Helmholtz vortices: Two‐fluid simulations including finite electron inertial effects
Authors: Nakamura T. K. M. , Fujimoto M.
Published: November 2005

We have performed two‐dimensional two‐fluid simulations including finite electron inertial effects to investigate the cross‐scale coupling in the evolution of MHD‐scale Kelvin‐Helmholtz (KH) mode. We focus on the model in which density is uniform and only the in‐plane magnetic field component is present. The effects of the velocity jump across the shear layer and those of the variation of the magnetic field intensity across the shear layer are considered. When the shear is strong enough to make a KH vortex highly rolled‐up, within‐the‐vortex reconnection is seen to play crucial roles in determining the structure of the large‐scale vortex itself. Especially when the magnetic field intensity is significantly unbalanced across the shear layer, injection of a magnetic bubble is seen to result from the reconnection process.
Decrease of emissions required to stabilize atmospheric CO2 due to positive carbon cycle–climate feedbacks
Authors: Matthews H. Damon
Published: November 2005

Positive feedbacks between the carbon cycle and climate have the potential to accelerate the accumulation of atmospheric CO2 over the next century. Here, I address the question of how climate‐induced carbon cycle changes could affect the emissions required to stabilize atmospheric CO2 at 1000 ppmv. From a coupled climate‐carbon cycle simulation, I calculated emissions that are consistent with a prescribed CO2 stabilization pathway. By comparing a coupled simulation with a second constant‐climate simulation, I show that carbon cycle‐climate feedbacks lead to large decreases in allowable emissions. Cumulative emissions are reduced by 94, 230 and 754 GtC between 2005 and years 2050, 2100 and 2350 respectively. Annual differences are largest at 2080, where emissions are reduced by 2.8 GtC/year. Further, while terrestrial feedbacks dominate for the next two centuries, the effect of ocean feedbacks on allowable emissions begin to exceed that of terrestrial feedbacks around the year 2250.
Significant latitudinal gradient in the surface ozone spring maximum over East Asia
Authors: Tanimoto Hiroshi , Sawa Yousuke , Matsueda Hidekazu , Uno Itsushi , Ohara Toshimasa , Yamaji Kazuyo , Kurokawa Jun‐ichi , Yonemura Seiichiro
Published: November 2005

The climatology of surface ozone over East Asia was investigated at a wide range of latitudes by integrating continuous measurements from Japanese monitoring networks. Although a spring maximum and a summer minimum were observed at all seven remote stations, significant latitudinal differences in the seasonal cycles were found, particularly in spring. At low latitudes (20–30°N) the spring maximum appears in March, while it appears in April at high latitudes (40–50°N), and in May at middle latitudes (30–40°N). A regional‐scale chemical transport model was applied to examine factors contributing to the latitudinal dependence observed. The model reproduces the latitudinal gradient and the overall seasonal variations well, and suggests that transport patterns of Asian continental outflow coupled with photochemistry result in latitudinal inhomogeneity over East Asia. These results highlight the key role of dynamical processes in modulating the amplitude and phase of the spring maximum in surface ozone.
Mesospheric planetary waves over Antarctica during 2002
Authors: Espy P. J. , Hibbins R. E. , Riggin D. M. , Fritts D. C.
Published: November 2005

Wind measurements from a series of atmospheric radars located around Antarctica have been used to characterize the mesospheric planetary‐wave field during the winter of 2002. Combining winds from the medium‐frequency (MF) radar at Rothera (68°S, 68°W) and the SuperDARN high‐frequency meteor‐wind radars at Halley (76°S, 27°W), Sanae (72°S, 3°W) and Syowa (69°S, 40°E) stations, we have been able to measure the period, wavenumber and propagation direction of the most prominent planetary waves. The results show that the planetary‐wave field before the unusual stratospheric warming in 2002 was dominated by a very long‐period (τ ≈ 43 days), westward and upward‐propagating zonal planetary wavenumber 1. However, after the stratospheric warming events began in late winter, the character of the wave field changed and a shorter period (τ ≈ 14 days), westward, zonal wavenumber 1 became established. It would appear that the previously reported oscillations of the mesospheric hydroxyl airglow temperatures at Rothera and Halley, which were strongly anti‐correlated to the meridional wind, were the result of these planetary waves.
Collision of barchan dunes as a mechanism of size regulation
Authors: Hersen Pascal , Douady Stéphane
Published: November 2005

Barchans are propagating crescentic dunes that form in arid regions where strong, unidirectional winds blow across a firm soil lightly covered with sand. Recently, solitary barchan dunes have been shown to be unstable towards sand flux variation either growing to form mega‐dunes or shrinking and disappearing when perturbed from equilibrium. However, observations of large corridors of barchan dunes in the field suggest that these bedforms are stable over long periods of time. Since dunes' migration rates are inversely proportional to their size, barchans of different size must collide and these collisions may be crucial in maintaining the stability of dunes in nature. Here, we first explain the unstable behavior of solitary barchans and then illustrate, using down‐scaled physical experiments, the qualitative dynamics of binary collisions. A stability analysis, inspired by these experiments, suggests that collisions may indeed regulate the size of barchans migrating in a corridor by redistributing sand from large dunes to smaller ones.
Conditions for plasma emission in the solar wind and very local interstellar medium (VLISM)
Authors: Mitchell J. J. , Cairns Iver H. , Robinson P. A.
Published: November 2005

Plasma emission at radio frequencies is important in many regions of the solar system and very local interstellar medium (VLISM). This emission, induced by an unstable beam of electrons, can occur owing to either nonlinear three‐wave decay interactions involving Langmuir waves, ion sound waves, and transverse waves or STI. Here recently obtained conditions for decay dominating STI and expressions for the combined efficiencies of decay and STI processes are applied to several phenomena: (1) type II and III solar radio bursts, both in the corona and in the solar wind, and (2) emission associated with global merged interaction region (GMIR) shocks which propagate through the solar system, and inner and outer heliosheath plasmas. The shock‐associated electron distributions are computed using a shock drift acceleration model. It is found that decay should dominate STI for type II and III bursts and that the conditions for decay dominating STI reduce the emission predicted by decay processes by ≲ a factor of 2. Similar results are found for GMIR related emission in the solar wind. In the portion of the VLISM where the electron distribution is primed with a superthermal tail the conditions are less severe; however, outside the primed region the conditions are important.
Ocean wave directional spectra estimation from an HF ocean radar with a single antenna array: Observation
Authors: Hisaki Yukiharu
Published: November 2005

A method of estimating ocean wave directional spectra using a]high‐frequency (HF) radar with a single antenna array was applied to actual ocean data. This method incorporates the wave energy balance equation and the continuity equation of wind vectors into the inversion method to solve the integral equation which relates a Doppler spectrum to wave spectra. This method uses dynamic extrapolation to estimate wave spectra at positions where the signal‐to‐noise (SN) ratio in Doppler spectra is not high. The agreement of wave heights with in situ observation is good. Additionally, there is a correlation between radar‐estimated sea surface winds and winds near the HF radar observation area. The method under consideration was found to be able to estimate wave directional spectra in swell conditions.
Diurnal cycle of tropical precipitation in Tropical Rainfall Measuring Mission (TRMM) satellite and ocean buoy rain gauge data
Authors: Bowman Kenneth P. , Collier J. Craig , North Gerald R. , Wu Qiaoyan , Ha Eunho , Hardin James
Published: November 2005

The climatological diurnal cycle of precipitation in the tropics is analyzed using data from rain gauges on ocean buoys and satellite measurements by the Tropical Rainfall Measuring Mission (TRMM) satellite. The ocean buoy data are from the NOAA/Pacific Marine Environmental Laboratory Tropical Atmosphere‐Ocean/Triangle Trans‐Ocean buoy Network in the tropical Pacific Ocean. TRMM data are from the precipitation radar (PR) and the TRMM microwave imager (TMI). Climatological hourly mean precipitation rates are analyzed in terms of the diurnal and semidiurnal harmonics. Both data sets confirm an early morning peak in precipitation over ocean regions. The amplitude of the diurnal harmonic over the oceans is typically less than 25% of the mean precipitation rate. Over tropical land masses the rainfall peaks in the afternoon and evening hours. The relative amplitude of the diurnal harmonic over land is larger than over the ocean, often exceeding 50% of the mean rain rate. Previously noted differences between the TMI and PR rainfall retrievals persist in the diurnal cycle. On average the TMI measures more rainfall than the PR and has a larger diurnal variation. Phase differences between the two instruments do not show a consistent bias.
A criterion for new particle formation in the sulfur‐rich Atlanta atmosphere
Authors: McMurry P. H. , Fink M. , Sakurai H. , Stolzenburg M. R. , Mauldin R. L. , Smith J. , Eisele F. , Moore K. , Sjostedt S. , Tanner D. , Huey L. G. , Nowak J. B. , Edgerton E. , Voisin D.
Published: November 2005

A simple dimensionless parameter, L, is shown to determine whether or not new particle formation can occur in the atmosphere on a given day. The criterion accounts for the probability that clusters, formed by nucleation, will coagulate with preexisting particles before they grow to a detectable size. Data acquired in an intensive atmospheric measurement campaign in Atlanta, Georgia, during August 2002 (ANARChE) were used to test the validity of this criterion. Measurements included aerosol size distributions down to 3 nm, properties and composition of freshly nucleated particles, and concentrations of gases including ammonia and sulfuric acid. Nucleation and subsequent growth of particles at this site were often dominated by sulfuric acid. New particle formation was observed when L was less than ∼1 but not when L was greater than ∼1. Furthermore, new particle formation was only observed when sulfuric acid concentrations exceeded 5 × 106 cm−3. The data suggest that there was a positive association between concentrations of particles produced by nucleation and ammonia, but this was not shown definitively. Ammonia mixing ratios during this study were mostly in the 1 to 10 ppbv range.
Equatorial Kelvin wave signatures in ozone profile measurements from Global Ozone Monitoring Experiment (GOME)
Authors: Timmermans R. M. A. , van Oss R. F. , Kelder H. M.
Published: November 2005

This study investigates the ability to derive height‐resolved information on equatorial Kelvin wave activity from three different Global Ozone Monitoring Experiment (GOME) ozone profile data sets. The ozone profiles derived using the Ozone Profile Retrieval Algorithm (OPERA) based on optimal estimation and the Neural Network Ozone Retrieval System (NNORSY) both show Kelvin wave signals in agreement with previously identified signals in the GOME total ozone columns. However, because of the inadequate vertical resolution, these two data sets are not able to resolve the vertical structure of the Kelvin wave activity. The third data set, consisting of assimilated OPERA ozone profiles, does provide height‐resolved information on Kelvin wave activity that is consistent with results from the analysis of GOME total ozone columns and ECMWF Re‐Analysis (ERA‐40) temperature data. Largest Kelvin‐wave‐induced perturbations of up to 0.69 DU/km coincide with the maximum vertical gradient in ozone around 35 hPa and show an in‐phase relationship with temperature perturbations in ERA‐40 as expected from theoretical considerations. These results indicate that the ozone perturbations in the lower stratosphere and in the total column of ozone are transport related. Between 10 and 1 hPa, large Kelvin‐wave‐induced fluctuations in ozone mixing ratio are present that, however, because of their small contribution to the total column, do not constitute a large contribution to the total ozone column perturbations. The ozone perturbations between 10 and 1 hPa show an out‐of‐phase relationship with temperature perturbations in ERA‐40, indicating that the perturbations can either be caused by transport effects or photochemical influences.
High‐precision determination of the changing isotopic composition of atmospheric N2O from 1990 to 2002
Authors: Röckmann Thomas , Levin Ingeborg
Published: November 2005

High‐precision nitrous oxide (N2O) concentration and isotope ratio measurements have been carried out on archived air samples from the Antarctic station Neumayer covering the period 1990–2002. The results show that the increase in the N2O mixing ratio over this period is accompanied by a significant decrease in the heavy isotope content. The temporal isotope trends amount to (−0.040 ± 0.003)‰/yr for δ15N (the average of both nitrogen positions) and (−0.021 ± 0.003)‰/yr for δ18O. The individual trends for the terminal (position 1) and central (position 2) nitrogen atoms within the N2O molecule are (−0.064 ± 0.016)‰/yr for 1δ15N and (−0.014 ± 0.016)‰/yr for 2δ15N. The average 15N and 18O trends compare well with recent results from measurements on air extracted from polar firn and ice, confirming earlier estimates that isotopically depleted N2O, mainly from soil emissions, is responsible for a large fraction of the observed N2O increase in the atmosphere. The position‐dependent 15N determinations show a strong difference between the two positions. This is in disagreement with the firn and ice core data, which imply similar fractionations at both positions.
Optical properties of low band gap alternating copolyfluorenes for photovoltaic devices
Authors: Persson Nils-Krister , Sun Mengtao , Kjellberg Pär , Pullerits Tönu , Inganäs Olle
Published: November 2005

In a joint experimental and theoretical work the optical response and excited-state character of two novel conjugated polymers for photovoltaic applications are studied. The polymers, alternating polyfluorene (APFO) Green 1 and APFO Green 2, are both copolymers of fluorene, thiophene, and electron accepting groups. The band gaps are extended into the red and near infrared with onsets of 780 and 1000 nm, respectively, due to alternating donor and acceptor moieties along the polymer chain. Spectroscopic ellipsometry and subsequent modeling made it possible to extract the dielectric function in the range of 260–1200 nm. Semiempirical quantum chemical calculations (ZINDO) revealed the character of the main electronic transitions in the studied spectral region. The spectral band just above 400 nm was assigned to a delocalized π−π* transition for both polymers. The red band lying at 622 and 767 nm in the two polymers corresponds to an electronic state mainly occupying the acceptor units and having a strong charge-transfer character. We show that the ZINDO transition energies are valuable input to the application of Lorentz oscillators in modeling of the dielectric function of the polymer material.
Analytic and contour representations in the unit disk based on SU(1,1) coherent states
Authors: Lei C. , Vourdas A. , Wünsche A.
Published: November 2005

A contour representation in the unit disk based on SU(1,1) coherent states is introduced. The scalar product is given by a contour integral. The regions of convergence of the functions representing ket and bra states are studied. An analytic representation in the unit disk is also considered, where the scalar product is represented by an integral over the unit disk, with the Lobachevsky measure. Various relations which connect these analytic functions with other phase-space quantities are derived.
Liquid-vapor interfaces of water-acetonitrile mixtures of varying composition
Authors: Paul Sandip , Chandra Amalendu
Published: November 2005

Detailed molecular-dynamics simulations are carried out to investigate the equilibrium and dynamical properties of water-acetonitrile mixtures of varying composition. Altogether, we have simulated eight different systems of different concentrations of acetonitrile. The inhomogeneous density and anisotropic orientational profiles at interfaces, surface tension, and also the distribution of hydrogen bonds are calculated for both water and acetonitrile molecules. The dynamical aspects of the interfaces are investigated in terms of the anisotropic diffusion and dipole orientational relaxation of interfacial water and acetonitrile molecules. For both structural and dynamical properties, the behaviors of the interfaces are compared with those of the corresponding bulk phases. A comparison between the present theoretical results and experimental findings, wherever available, is also made to verify the usefulness of the molecular models employed in the present study for predicting interfacial properties.
X-ray photoelectron spectroscopy and structural analysis of amorphous SiOxNy films deposited at low temperatures
Authors: Cova P. , Poulin S. , Masut R. A.
Published: November 2005

We establish, using a tetrahedral model, the bonding properties of amorphous silicon oxynitride (a-SiOxNy) films deposited at low temperatures (LTs) by electron-cyclotron resonance chemical-vapor deposition (ECRCVD) on several substrates and under various conditions of gas flows and total gas pressure in a dilute mixture of SiH4+N2 in Ar. The atomic percentage of each tetrahedral unit incorporated in the film network is calculated from the deconvolution of the high-resolution x-ray photoelectron spectroscopy (XPS) spectra in the Si 2p3∕2 region and corroborated by the results obtained from both survey scans and the high-resolution XPS spectra in the N 1s region. The Si3N4 phase is the most important one and the only bonding unit which is incorporated in all our LT ECRCVD SiOxNy films. The incorporation of all the other component tetrahedrons depends strongly on growth conditions. The threshold values of the N∕Si atomic ratio for which intrinsic defects, such as Si–Si bonds, are not incorporated in the network depend on the O∕Si ratio incorporated in the films, mainly due to the competition between oxygen and nitrogen atoms in their reaction with silicon dangling bonds. The effect of the total gas pressure on the atomic percentages of the oxidation states present in the LT ECRCVD SiOxNy films is qualitatively similar to the effect of the ion bombarding energy or the plasma density. O–N bonds are present only in samples having high amount of oxygen and nitrogen in their networks. For these films, our results show unambiguously the presence of the N–Si2O tetrahedron and suggest that N–Si3−νOν tetrahedrons with ν⩾2 are not incorporated in their networks. A correlation is observed between the N–Si2O and the Si–O3(ON) tetrahedrons whose component peak is localized at (104.0±0.2)eV in the Si 2p3∕2 region of the XPS data, which suggests that both bonding units coexist in these films as some sort of complex bonding configuration.
Room-temperature nanowire ultraviolet lasers: An aqueous pathway for zinc oxide nanowires with low defect density
Authors: Hirano Shingo , Takeuchi Nobuo , Shimada Shu , Masuya Kyosuke , Ibe Katsuhiko , Tsunakawa Hideo , Kuwabara Makoto
Published: November 2005

We report the realization of a low-temperature aqueous pathway for the chemical synthesis of zinc oxide (ZnO) nanowires with low defect density and their room-temperature ultraviolet lasing behavior at low pump fluence. The concentration of solutes determined not only the size of individual nanowires, which influences their optical waveguiding behavior, but also their lattice defect density, which affects the efficiency of ultraviolet emission. The optimal synthesis conditions led to low-temperature growth of ZnO nanowires that showed room-temperature ultraviolet lasing at a low threshold of pump fluence. Based on our experimental results and optical waveguide theory, we report two important factors for realizing high-quality ZnO nanowires that show room-temperature ultraviolet lasing via a low-temperature aqueous approach: control of the density of defects generated in aqueous solutions and the optimal microstructure of the grown nanowires to produce strong optical confinement.
Terahertz radiation from heavy-ion-irradiated In0.53Ga0.47As photoconductive antenna excited at 1.55μm
Authors: Chimot N. , Mangeney J. , Joulaud L. , Crozat P. , Bernas H. , Blary K. , Lampin J. F.
Published: November 2005

We investigate terahertz (THz) emission from heavy-ion-irradiated In0.53Ga0.47As photoconductive antennas excited at 1550 nm. The carrier lifetime in the highly irradiated In0.53Ga0.47As layer is less than 200 fs, the steady-state mobility is 490cm2V−1s−1, and the dark resistivity is 3Ωcm. The spectrum of the electric field radiating from the Br+-irradiated In0.53Ga0.47As antenna extends beyond 2 THz. The THz electric field magnitude is shown to saturate at high optical pump fluence, and the saturation fluence level increases with the irradiation dose, indicating that defect center scattering has a significant contribution to the transient mobility.
The effect of excimer laser pretreatment on diffusion and activation of boron implanted in silicon
Authors: Monakhov E. V. , Svensson B. G. , Linnarsson M. K. , La Magna A. , Italia M. , Privitera V. , Fortunato G. , Cuscunà M. , Mariucci L.
Published: November 2005

We have investigated the effect of excimer laser annealing (ELA) on transient enhanced diffusion (TED) and activation of boron implanted in Si during subsequent rapid thermal annealing (RTA). It is observed that ELA with partial melting of the implanted region causes reduction of TED in the region that remains solid during ELA, where the diffusion length of boron is reduced by a factor of ∼4 as compared to the as-implanted sample. This is attributed to several mechanisms such as liquid-state annealing of a fraction of the implantation induced defects, introduction of excess vacancies during ELA, and solid-state annealing of the defects beyond the maximum melting depth by the heat wave propagating into the Si wafer. The ELA pretreatment provides a substantially improved electrical activation of boron during subsequent RTA.
Determination of elastic constants of a fiber-textured gold film by combining synchrotron x-ray diffraction and in situ tensile testing
Authors: Faurie D. , Renault P.-O. , Le Bourhis E. , Goudeau Ph.
Published: November 2005

The elastic behavior of gold thin films deposited onto Kapton substrate has been studied using in situ tensile tester in a four-circle goniometer on a synchrotron beam line (LURE facility, France). The mechanical description of the substrate-thin film composite structure has been developed to determine the stress tensor in the film while the strong {111} fiber texture was taken into account using the crystallite group method (CGM). CGM strain analysis allowed us to forecast the nonlinear relationship between strain and sin2Ψ obtained for the thin films due to the strong anisotropy of gold. A least-square method was used to fit the overall experimental data with good accuracy and allows determining all single-crystal elastic constants.
Dependence of electrical properties of epitaxial Pb(Zr,Ti)O3 thick films on crystal orientation and Zr∕(Zr+Ti) ratio
Authors: Yokoyama Shintaro , Honda Yoshihisa , Morioka Hitoshi , Okamoto Shoji , Funakubo Hiroshi , Iijima Takashi , Matsuda Hirofumi , Saito Keisuke , Yamamoto Takashi , Okino Hirotake , Sakata Osami , Kimura Shigeru
Published: November 2005

Epitaxial Pb(Zr,Ti)O3(PZT) films, 1.5–2.0μm in thickness, with a Zr∕(Zr+Ti) ratio ranging from 0.20 to 0.75 were grown on (100)c-,(110)c-, and (111)c-oriented SrRuO3∕∕SrTiO3 substrates at 600 °C by metal-organic chemical vapor deposition (MOCVD). The effects the Zr∕(Zr+Ti) ratio had on the crystal structure, dielectric and ferroelectric properties, and piezoelectric response of these films with different crystal orientations were systematically investigated. We ascertained from x-ray-diffraction reciprocal-space-mapping analysis that (001)T-∕(100)T-∕(100)R-,(101)T-∕(110)T-∕(110)R-∕(101¯)R-, and (111)T-∕(111)R-∕(111¯)R-oriented films had epitaxially grown on the respective (100)c-,(110)c-, and (111)c-oriented SrRuO3∕∕SrTiO3 substrates. The constituent phase changed from a tetragonal single phase, a mixture phase of a tetragonal and rhombohedral, to a rhombohedral single phase with increasing Zr∕(Zr+Ti) ratio irrespective of the orientation of the substrates. However, the range of the Zr∕(Zr+Ti) ratio of the film with the mixture phase differed depending on crystal orientation. This suggests that the stress relaxation process applied from the substrates changed due to crystal orientation. The relative dielectric constant was maximum for films with the mixture phase regardless of the crystal orientation. Remanent polarization was also maximum for these films on the (111)cSrRuO3∕∕SrTiO3 substrates, while it was minimum on the (100)c- and (110)c-oriented SrRuO3∕∕SrTiO3 substrates. Films with two phases coexisting had larger electric-field-induced strain than films with a single tetragonal or rhombohedral phase for the (111)-oriented films, but there were no remarkable changes in the (100)- and (110)-oriented films. Small ac signal measurements suggested that domain-wall motions easily occurred in the (111)-oriented films with the mixture phase compared with other orientations. These results indicated that the larger field-induced strain of the (111)-oriented PZT films consisting of a mixture of tetragonal and rhombohedral phases largely contributed to extrinsic factors such as domain-wall motions and phase transformation due to the applied electric field.
Size-controlled synthesis and characterization of thiol-stabilized gold nanoparticles
Authors: Frenkel A. I. , Nemzer S. , Pister I. , Soussan L. , Harris T. , Sun Y. , Rafailovich M. H.
Published: November 2005

Size-controlled synthesis of nanoparticles of less than a few nanometers in size is a challenge due to the spatial resolution limit of most scattering and imaging techniques used for their structural characterization. We present the self-consistent analysis of the extended x-ray absorption fine-structure (EXAFS) spectroscopy data of ligand-stabilized metal nanoclusters. Our method employs the coordination number truncation and the surface-tension models in order to measure the average diameter and analyze the structure of the nanoparticles. EXAFS analysis was performed on the two series of dodecanethiol-stabilized gold nanoparticles prepared by one-phase and two-phase syntheses where the only control parameter was the gold/thiol ratio ξ, varied between 6:1 and 1:6. The two-phase synthesis resulted in the smaller particles whose size decreased monotonically and stabilized at 16Å when ξ was lowered below 1:1. This behavior is consistent with the theoretically predicted thermodynamic limit obtained previously in the framework of the spherical drop model of Au nanoparticles.
Strain mapping with parts-per-million resolution in synthetic type-Ib diamond plates
Authors: Macrander Albert T. , Krasnicki Szczesny , Zhong Yuncheng , Maj Josef , Chu Yong S.
Published: November 2005

A general method to map strain with parts per million (ppm) resolution in single-crystal wafers and plates is demonstrated. An x-ray technique has been used to obtain separate maps of strain and tilt across synthetic diamond growth sectors. Data consisting of rocking curve maps obtained with a charge coupled device detector were analyzed. The strain results image the growth sectors and reveal a strain pileup near the sector boundaries. The diamond was yellow to the eye due to nitrogen impurities. Not only the topography of the strain map, but also the strain magnitudes, are consistent with the strain arising from nitrogen impurities. High strain resolution in the ppm range is needed to observe these effects.
Double amorphous silicon-carbide p-layer structures producing highly stabilized pin-type protocrystalline silicon multilayer solar cells
Authors: Myong Seung Yeop , Lim Koeng Su , Pears Joshua M.
Published: November 2005

We have applied double p-type amorphous silicon-carbide (p-a-SiC:H) layer structures to pin-type protocrystalline silicon (pc-Si:H) multilayer solar cells. The less-pronounced initial short-wavelength quantum efficiency variation against the biased voltage and the wide overlap of dark current—voltage (JD-V) and short-circuit current—open-circuit voltage (Jsc-Voc) characteristics prove that the double p-a-SiC:H layer structure successfully reduces recombination at the p∕i interface. Therefore, we achieved highly stabilized efficiency of 9.0% without any backreflector.
Self-assembled switches based on electroactuated multiwalled nanotubes
Authors: Dujardin E. , Derycke V. , Goffman M. F. , Lefèvre R. , Bourgoin J. P.
Published: November 2005

A fabrication process for nanoelectromechanical systems (NEMS) based on multiwalled carbon nanotubes (CNTs) suspended across metallic trenches is described. The process is versatile and allows the production of CNT-NEMS with singly or doubly clamped nanotubes at an adjustable height above a bottom electrode. When a voltage bias is applied between the nanotube and the bottom electrode, the devices act as very efficient electrical switches. Surface functionalization of the bottom electrode with a self-assembled monolayer is implemented to improve the switching reversibility. Moreover, it opens opportunities to use these CNT-NEMS as a vertical cross-bar junction for molecular electronics studies.
Uncooled tunable pyroelectric response of antiferroelectric Pb0.97La0.02(Zr0.65Sn0.22Ti0.13)O3 perovskite
Authors: Chan Wai-Hung , Xu Zhengkui , Zhai Jiwei , Chen Haydn
Published: November 2005

Pb 0.97 La 0.02 ( Zr 0.65 Sn 0.22 Ti 0.13 ) O 3 ceramic was confirmed to be in an antiferroelectric (AFE) phase at T<170°C by macroscopic and microscopic studies. The electric-field-induced ferroelectric (FE) state was found to exhibit a much longer lifetime than the reasonable laboratory measuring time scale at T<60°C, which has led to the frequent misinterpretation of this material system as FE. The dc bias dependence of the dielectric and pyroelectric properties was studied as a function of temperature. The poled sample exhibited a low dissipation factor (tanδ∼0.03), a large transient pyroelectric coefficient of the order of 10−3–10−2Cm−2K−1, and excellent dc tunability at the FE-to-AFE transition temperature (39°C∕kV∕mm). The possible application of this material to uncooled tunable pyroelectric thermal sensing is also discussed.
Suppression of ferromagnetism due to hole doping in Zn1−xCrxTe grown by molecular-beam epitaxy
Authors: Ozaki N. , Okabayashi I. , Kumekawa T. , Nishizawa N. , Marcet S. , Kuroda S. , Takita K.
Published: November 2005

Electric and magnetic properties were investigated on p-type Zn1−xCrxTe doped with nitrogen (N) as an acceptor. Thin films of p-Zn1−xCrxTe(x≦0.09) were grown by molecular-beam epitaxy with the supply of N2 gas excited by rf plasma. With the increase of Cr composition x at an almost fixed N concentration of the order of 1020cm−3, the temperature dependence of resistivity changed from metallic behavior to an insulating one, accompanied with a significant decrease of the hole concentration. The magnetization measurements revealed that ferromagnetic behaviors observed in undoped Zn1−xCrxTe were suppressed due to the nitrogen doping; with N concentrations of the order of 1020cm−3, hysteresis loops in the magnetization curve disappeared, the magnitude of magnetization decreased, and the ferromagnetic transition were not observed down to 2 K according to the Arrott plot analysis. These experimental findings are discussed on the basis of the ferromagnetic double exchange interaction which is considered to work on the Cr 3d impurity level formed in the band gap of ZnTe.
Space-charge-limited bipolar flow in a nano-gap
Authors: Koh W. S. , Ang L. K. , Lau S. P. , Kwan T. J. T.
Published: November 2005

This paper presents a quantum model of space-charge limited (SCL) bipolar flow in a nano-sized planar gap, including the effects of electron tunneling and exchange-correlation. It is found that the classical scaling of the SCL bipolar flow is no longer valid when the gap spacing D is comparable or smaller than the electron’s de Broglie wavelength at gap voltage Vg. The classical value of the SCL bipolar electron flow is greatly enhanced due to the electron tunneling through the space-charge electric potential created by both the electrons and ions. The space-charge effect of ions is less significant (compared to electron tunneling) in the deep quantum regime that the quantum SCL bipolar flow is nearly identical to the unipolar electron flow (or quantum Child-Langmuir law).
Initial nitride formation at Si∕3C–SiC(100)3×2 interface by oxynitridation
Authors: Radtke C. , Enriquez H. , Arnault J. C. , Soukiassian P. , Moras P. , Crotti C. , Perfetti P.
Published: November 2005

Nitric oxide interaction with 3C–SiC(100)3×2 and Si-3×2∕3C–SiC(100)3×2 surfaces is investigated by synchrotron radiation-based core level photoemission spectroscopy. At 25°C, NO exposures result in oxynitride formation, while annealing at 1000°C removes oxygen leading to a nitride layer. Most interestingly, the results suggest stoichiometric Si3N4 layer formation at Si-3×2∕3C–SiC(100)3×2 interface. This finding is of interest in limiting dopant diffusion and in defect passivation so critical at insulator/SiC interfaces.
High coercivity in nanocrystalline carbides Sm(Fe,Ga)9C
Authors: Bessais L. , Dorolti E. , Djéga-Mariadassou C.
Published: November 2005

The structural and magnetic properties of metastable hexagonal SmFe9−yGayC compounds, with y=0.25, 0.5, 0.75, and 1, have been investigated by means of powder x-ray diffraction, magnetic measurements, and high-resolution transmission electron microscopy. After carbonation, the Rietveld analysis points out an anisotropic lattice expansion more important for the carbon site. The Curie temperatures are systematically 20to70K higher than those of the homologous Sm2(Fe,Ga)17 carbides. A record coercivity of 27kOe is obtained for y=0.25 with annealing temperature of the noncarbonated powder at 710°C which corresponds to an optimal grain size around 28nm. The MR∕M(90kOe) ratio of 0.57 combined with high coercivity and high TC makes this alloy suitable for permanent magnet applications.
Upwelling along the western barrier reef of New Caledonia
Authors: Hénin Christian , Cresswell G. R.
Published: November 2005

Temperature decreases of up to 5°C at an automatic station at ~10 m depth at the outer reef of western New Caledonia signalled the occurrence of upwelling. The decreases are related to south-easterly wind events and they can take up to 5 days to develop. Successive wind events can depress the temperature for as much as 1 month. An upwelling shows in thermal satellite imagery as a band of cold water ~10 km wide and as long as several hundred kilometres just outside the reef. The cold water frequently spreads out to sea. The upwellings are more common in summer (October to March) than in winter. During lengthy periods of low wind speeds, the waters outside the reef appear to be overrun by warm water from farther north. The frequent occurrence of the warm water layer in the north may partly explain why upwellings are more common along the southern half of the reef. The entire lagoon cools in winter; most of the lagoon warms in summer, except at the southern end where the waters are cool, perhaps from tidal mixing.
Age and growth of larval Atlantic sailfish, Istiophorus platypterus
Authors: Luthy Stacy A. , Serafy Joseph E. , Cowen Robert K. , Denit Kelly L. , Sponaugle Su
Published: November 2005

Of the Atlantic istiophorid billfishes, larval age–size relationships and growth rates have been examined only for blue marlin (Makaira nigricans). Using otolith microincrement analysis, we describe age–length and age–weight relationships for larval sailfish (Istiophorus platypterus) collected from the Straits of Florida. Sagittae and lapilli were dissected from 70 larvae ranging from 2.8 to 15.2 mm in (notochord or standard) length. Comparisons between otolith images obtained by light microscopy and scanning electron microscopy indicated that increment widths were well within the resolving power of light microscopy. Indirect evidence and published descriptions of larval blue marlin otoliths suggest daily increment deposition. Estimated ages of specimens ranged from 3 to 18 days. Length data were fitted to age estimates with an exponential model (R2 = 0.85). The estimated size-at-hatch for sailfish was 1.96 mm notochord length, and the daily instantaneous growth coefficient was 0.14. A power curve with exponent 3.05 described the length–dry weight relationship for sailfish. The instantaneous growth coefficient for an exponential regression of dry weight, converted from length, versus estimated age was 0.41. Growth in the length of sailfish larvae from the Straits of Florida was very similar to that described for blue marlin larvae from Exuma Sound, Bahamas.