bluuebunny/crossref_metadata_2025 huggingface dataset:
Die Auswirkungen der 12. und der 14. Novelle zum AMG auf die Forschung mit Arzneimitteln für Kinder
Authors: Kölch Michael , Lippert Hans-Dieter , Fegert Jörg M.
Published: March 2006

Zusammenfassung: Gegenstand: Die 12. Novelle des Arzneimittelgesetzes (AMG) setzt die EU-Direktive 2001/20/EG um und bringt Veränderungen für die universitäre Forschung in der Kinder- und Jugendpsychiatrie mit sich. Die 14. Novelle regelt u.a. die Kennzeichnung von Arzneimitteln. Methode: Die Auswirkungen auf verschiedene Bereiche der klinischen Forschung, die Gestaltung von klinischen Prüfungen mit und ohne Sponsor (IITs), auf die weitere Entwicklung der Pharmakosicherheit und die Arzneimittelentwicklung für Minderjährige werden anhand der bisherigen Praxis und der neuen Rechtslage dargestellt und zusammengefasst. Insbesondere wird auf die besonders relevanten Bereiche off-label use, Langzeitsicherheit, Anwendungsbeobachtungen und Therapieoptimierungsstudien eingegangen. Ergebnisse: Die neue Rechtslage lässt die bisherige Praxis der Anwendungsbeobachtungen und Therapieoptimierungsstudien nicht mehr zu, sondern vereinheitlicht Anforderungen und Verfahrensregeln für alle klinischen Prüfungen am Menschen. Schlussfolgerungen: Zwar sind die Voraussetzungen für qualitativ gute klinische Prüfungen und Arzneimittelentwicklungen durch die Möglichkeit fremdnütziger Forschung auch mit Minderjährigen gewachsen, aufgrund hoher regulativer Anforderungen dürften universitäre Forschungsvorhaben ohne Sponsoren eher erschwert werden.
Impact of global seismicity on sea level change assessment
Authors: Melini D. , Piersanti A.
Published: March 2006

We analyze the effect of seismic activity on sea level variations by computing the time‐dependent vertical crustal movement and geoid change due to coseismic deformations and postseismic relaxation effects. Seismic activity can affect both the absolute sea level, changing the Earth's gravity field and hence the geoid height, and the relative sea level (RSL), i.e., the radial distance between seafloor and geoid level. By using comprehensive seismic catalogs we assess the net effect of seismicity on tidal relative sea level measurements as well as on the global oceanic surfaces, and we obtain an estimate of absolute sea level variations of seismic origin. We modified the approach adopted in our previous analysis, considering the issue of water volume conservation by applying the sealevel equation, and we improved our computational methods, enabling us to evaluate the effect of an extremely large number of earthquakes on large grids covering the whole oceanic surface. These new potentialities allow us to perform more detailed investigations and to discover a quantitative explanation for the overall tendency of earthquakes to produce a positive global relative sea level variation. Our results confirm the finding of a previous analysis that on a global scale most of the signal is associated with a few giant thrust events and that RSL estimates obtained using tide gauge data can be sensibly affected by the seismically driven sea level signal. The recent measures of sea level obtained by satellite altimetry show a wide regional variation of sea level trends over the oceanic surface, with the largest deviations from the mean trend occurring in tectonically active regions. While our estimates of average absolute sea level variations turn out to be orders of magnitude smaller than the satellite‐measured variations, we can still argue that the mass redistribution associated with aseismic tectonic processes may contribute to the observed regional variability of sea level variations. A detailed study of these tectonic contributions is important to acquire a complete understanding of the global sea level variations and will be the subject of future investigations.
Occurrence of droughts and floods during the normal summer monsoons in the mid‐ and lower reaches of the Yangtze River
Authors: Wu Zhiwei , Li Jianping , He Jinhai , Jiang Zhihong
Published: March 2006

The daily precipitation data at 720 stations over China for the 1957–2000 period during summer (May–August) are used to investigate the droughts‐floods coexistence (DFC) phenomenon during the normal summer monsoons. A droughts‐floods coexistence index on seasonal timescale over the mid‐ and lower reaches of the Yangtze River (MLYRV) is defined to quantify this phenomenon and the associated ocean‐atmospheric features in the strong DFC years are examined statistically. Results demonstrate that the occurrence of the strong summer DFC in the MLYRV is of an increasing trend for the period of 1957–2000. The strong summer DFC in the MLYRV is often accompanied by the anomalously subseasonal oscillation of the western Pacific subtropical high, the low‐level westerly winds anomalies over the equatorial oceanic areas from the Indian Ocean to the western Pacific and the northward cross‐equatorial winds anomalies near Sumatra and Somalia during summer, the strong Southern Hemisphere annual mode during the preceding November through January, high sea surface temperature in the oceanic areas from the Arabian Sea to the South China Sea, and El Niño or the developing phase of El Niño in the 6 preceding months. All these offer some predictive signals for the summer DFC in the MLYRV.
New aerogeophysical view of the Antarctic Peninsula: More pieces, less puzzle
Authors: Ferraccioli F. , Jones P. C. , Vaughan A. P. M. , Leat P. T.
Published: March 2006

New airborne geophysical data reveal subglacial imprints of crustal growth of the Antarctic Peninsula by Mesozoic arc magmatism and terrane accretion along the paleo‐Pacific margin of Gondwana. Potential field signatures indicate that the Antarctic Peninsula batholith is a composite magmatic arc terrane comprising two distinct arcs, separated by a >1500 km‐long suture zone, similar to the Peninsular Ranges batholith in southern and Baja California. Aeromagnetic, aerogravity and geological data suggest that a mafic Early Cretaceous western arc was juxtaposed against a more felsic eastern arc which, in mid‐Cretaceous times, was intruded by highly magnetic tonalitic/granodioritic plutons of island arc affinity. Suturing of the two arcs against the Gondwana margin caused the mid‐Cretaceous Palmer Land orogenic event. Convergence and suturing may have been driven by two subduction zones or, alternatively, by a decrease in slab dip, leading to an inboard migration of the arc, as in California.
Seismic imaging of the aftershock zone of the 2001 Mw 7.7 Bhuj earthquake, India
Authors: Mandal Prantik , Pujol Jose
Published: March 2006

Detailed seismic tomography reveals that the 2001 Mw 7.7 Bhuj earthquake was associated with a 10–14% increase in Vp and Vs and a 10% decrease in Vp/Vs in the 10 to 35 km depth range covering a 2750 km2 area beneath the aftershock zone. This anomaly could be attributed to the existence of a lithological heterogeneity or a pluton of mafic composition that might have intruded during the rifting in early Jurassic (∼160 Ma). The Banni basin and the Wagad uplift are found to be associated with high velocity intrusive bodies extending from 5 to 35 km depth. A few patches of low Vp and Vs and high Vp/Vs between 10 to 30 km depth have also been detected on the causative 45° south dipping north Wagad fault (NWF) for the 2001 mainshock, which may be attributed to a fluid filled fractured rock matrix.
Enhanced positive water vapor feedback associated with tropical deep convection: New evidence from Aura MLS
Authors: Su Hui , Read William G. , Jiang Jonathan H. , Waters Joe W. , Wu Dong L. , Fetzer Eric J.
Published: March 2006

Recent simultaneous observations of upper tropospheric (UT) water vapor and cloud ice from the Microwave Limb Sounder (MLS) on the Aura satellite provide new evidence for tropical convective influence on UT water vapor and its associated greenhouse effect. The observations show that UT water vapor increases as cloud ice water content increases. They also show that, when sea surface temperature (SST) exceeds ∼300 K, UT cloud ice associated with tropical deep convection increases sharply with increasing SST. The moistening of the upper troposphere by deep convection leads to an enhanced positive water vapor feedback, about 3 times that implied solely by thermodynamics. Over tropical oceans when SST greater than ∼300 K, the ‘convective UT water vapor feedback’ inferred from the MLS observations contributes approximately 65% of the sensitivity of the clear‐sky greenhouse parameter to SST.
Salt dissolution and sinkhole formation along the Dead Sea shore
Authors: Shalev Eyal , Lyakhovsky Vladimir , Yechieli Yoseph
Published: March 2006

The formation of sinkholes at the Dead Sea area reflects subsurface cavities formed by salt dissolution. This dissolution is related to the recession of the Dead Sea; the groundwater level and the fresh/saline water interface along the shore decline at a similar rate to the rate of the Dead Sea recession, and brines that used to occupy layers below this interface are flushed out by freshwater. Our finite element modeling shows that dissolution of this salt layer is a plausible mechanism to explain the rapid creation of subsurface holes that collapse and form sinkholes. The positive feedback between the rate of flow, the rate of chemical reaction, and the change in permeability accelerates the dissolution processes and might result in “reactive infiltration instability” which is manifested in “fingers” of cavities, into which fluid is channeled, and salt is dissolved. The spacing between the sinkholes and the rate of their creation is controlled by several factors including properties of lineaments/faults, incoming groundwater flux, the salinity of the incoming groundwater, the rate of dissolution, the effective specific surface area, the permeability of the salt and clay layers, the permeability‐porosity relation, the dispersivity, and the thickness of the layers. We show that the creation of sinkholes occurs only under specific conditions. These conditions must cause an unstable dissolution front which then causes formation of cavities and eventually sinkholes. The simulations, which utilized the best estimated parameters of the studied area, yield results that are similar to those exhibited in the field.
Statistical uncertainty of eddy flux–based estimates of gross ecosystem carbon exchange at Howland Forest, Maine
Authors: Hagen S. C. , Braswell B. H. , Linder E. , Frolking S. , Richardson A. D. , Hollinger D. Y.
Published: March 2006

We present an uncertainty analysis of gross ecosystem carbon exchange (GEE) estimates derived from 7 years of continuous eddy covariance measurements of forest‐atmosphere CO2fluxes at Howland Forest, Maine, USA. These data, which have high temporal resolution, can be used to validate process modeling analyses, remote sensing assessments, and field surveys. However, separation of tower‐based net ecosystem exchange (NEE) into its components (respiration losses and photosynthetic uptake) requires at least one application of a model, which is usually a regression model fitted to nighttime data and extrapolated for all daytime intervals. In addition, the existence of a significant amount of missing data in eddy flux time series requires a model for daytime NEE as well. Statistical approaches for analytically specifying prediction intervals associated with a regression require, among other things, constant variance of the data, normally distributed residuals, and linearizable regression models. Because the NEE data do not conform to these criteria, we used a Monte Carlo approach (bootstrapping) to quantify the statistical uncertainty of GEE estimates and present this uncertainty in the form of 90% prediction limits. We explore two examples of regression models for modeling respiration and daytime NEE: (1) a simple, physiologically based model from the literature and (2) a nonlinear regression model based on an artificial neural network. We find that uncertainty at the half‐hourly timescale is generally on the order of the observations themselves (i.e., ∼100%) but is much less at annual timescales (∼10%). On the other hand, this small absolute uncertainty is commensurate with the interannual variability in estimated GEE. The largest uncertainty is associated with choice of model type, which raises basic questions about the relative roles of models and data.
Preface to special section: Atmospheric Radiation Measurement Program May 2003 Intensive Operations Period examining aerosol properties and radiative influences
Authors: Ferrare Richard , Feingold Graham , Ghan Steven , Ogren John , Schmid Beat , Schwartz Stephen E. , Sheridan Pat
Published: March 2006

Atmospheric aerosols influence climate by scattering and absorbing radiation in clear air (direct effects) and by serving as cloud condensation nuclei, modifying the microphysical properties of clouds, influencing radiation and precipitation development (indirect effects). Much of present uncertainty in forcing of climate change is due to uncertainty in the relations between aerosol microphysical and optical properties and their radiative influences (direct effects) and between microphysical properties and their ability to serve as cloud condensation nuclei at given supersaturations (indirect effects). This paper introduces a special section that reports on a field campaign conducted at the Department of Energy Atmospheric Radiation Measurement site in north central Oklahoma in May 2003, examining these relations using in situ airborne measurements and surface‐, airborne‐, and space‐based remote sensing.
Non-Abelian gauge field theory in scale relativity
Authors: Nottale Laurent , Célérier Marie-Noëlle , Lehner Thierry
Published: March 2006

Gauge field theory is developed in the framework of scale relativity. In this theory, space-time is described as a nondifferentiable continuum, which implies it is fractal, i.e., explicitly dependent on internal scale variables. Owing to the principle of relativity that has been extended to scales, these scale variables can themselves become functions of the space-time coordinates. Therefore, a coupling is expected between displacements in the fractal space-time and the transformations of these scale variables. In previous works, an Abelian gauge theory (electromagnetism) has been derived as a consequence of this coupling for global dilations and/or contractions. We consider here more general transformations of the scale variables by taking into account separate dilations for each of them, which yield non-Abelian gauge theories. We identify these transformations with the usual gauge transformations. The gauge fields naturally appear as a new geometric contribution to the total variation of the action involving these scale variables, while the gauge charges emerge as the generators of the scale transformation group. A generalized action is identified with the scale-relativistic invariant. The gauge charges are the conservative quantities, conjugates of the scale variables through the action, which find their origin in the symmetries of the “scale-space.” We thus found in a geometric way and recover the expression for the covariant derivative of gauge theory. Adding the requirement that under the scale transformations the fermion multiplets and the boson fields transform such that the derived Lagrangian remains invariant, we obtain gauge theories as a consequence of scale symmetries issued from a geometric space-time description.
Flow equations for uplifting half-flat to Spin(7) manifolds
Authors: Misra Aalok
Published: March 2006

In this supplement to the paper by Franzen et al. [Fortschr. Phys. (to be published)], we discuss the uplift of half-flat sixfolds to Spin(7) eightfolds by fibration of the former over a product of two intervals. We show that the same can be done in two ways—one, such that the required Spin(7) eightfold is a double G2 sevenfold fibration over an interval, the G2 sevenfold itself being the half-flat sixfold fibered over the other interval, and second, by simply considering the fibration of the half-flat sixfold over a product of two intervals. The flow equations one gets are an obvious generalization of the Hitchin’s flow equations [to obtain sevenfolds of G2 holonomy from half-flat sixfolds [Hitchin (2001)]]. We explicitly show the uplift of the Iwasawa using both methods, thereby proposing the form of new Spin(7) metrics. We give a plausibility argument ruling out the uplift of the Iwasawa manifold to a Spin(7) eightfold at the “edge,” using the second method. For Spin(7) eightfolds of the type X7×S1, X7 being a sevenfold of SU(3) structure, we motivate the possibility of including elliptic functions into the “shape deformation” functions of sevenfolds of SU(3) structure of Franzen et al. via some connections between elliptic functions, the Heisenberg group, theta functions, the already known D7-brane metric [Greene et al., Nucl. Phys. B 337, 1 (1990)], and hyper-Kähler metrics obtained in twistor spaces by deformations of Atiyah-Hitchin manifolds by a Legendre transform [Chalmers, Phys. Rev. D 58, 125011 (1998)].
Time-dependent barrier passage of a non-Ohmic damping system
Authors: Bao Jing-Dong
Published: March 2006

We consider a particle passing over the saddle point of an inverse harmonic potential, which is described by a generalized Langevin equation with a non-Ohmic damping of power exponent δ. The time-dependent passing probability and transmission coefficient are obtained analytically by using the reaction flux method. It is shown that the overshooting phenomenon for the passing probability appears in the regime 0<δ<1 and the backflow recrossing over the saddle point is observed, where a nonmonotonous time dependence of the passage probability is detected. The long memory aspect of friction is at the origin of this behavior. Thus the steady transmission coefficient is also a nonmonotonous function of δ.
Organic light-emitting diodes based on a cohost electron transporting composite
Authors: Fong H. H. , Choy Wallace C. H. , Hui K. N. , Liang Y. J.
Published: March 2006

The efficiency of green organic electroluminescent devices have been improved by cohosting the electron dominant complex, 4,7-diphenyl-1,10-phenanthroline into the traditional electron transporting layer of tris (8-hydroxyquinoline) aluminum. In this cohost strategy, we demonstrate that the luminous efficiency is enhanced by >20% while the driving voltage can be reduced by ∼30% in a uniformly mixed composition as compared to the traditional device configuration. The corresponding device lifetime under atmospheric condition is extended by a factor of ∼1.8, attributed to the reduction of the accumulated positive charges near the electron-hole recombination regime. Results indicate that the knowledge of bulk conductivity engineering of organic n-type transporters is essential in enhancing organic light-emitting devices.
On Shannon entropies in μ-deformed Segal-Bargmann analysis
Authors: de Jesús Pita Ruiz Velasco Claudio , Sontz Stephen Bruce
Published: March 2006

We consider a μ-deformation of the Segal-Bargmann transform, which is a unitary map from a μ-deformed quantum configuration space onto a μ-deformed quantum phase space (the μ-deformed Segal-Bargmann space). Both of these Hilbert spaces have canonical orthonormal bases. We obtain explicit formulas for the Shannon entropy of some of the elements of these bases. We also consider two reverse log-Sobolev inequalities in the μ-deformed Segal-Bargmann space, which have been proved in a previous work, and show that a certain known coefficient in them is the best possible.
Theoretical investigation of the electronic properties, and first and second harmonic generation for cadmium chalcogenide
Authors: Reshak Ali Hussain
Published: March 2006

We present the results of the ab initio theoretical study of the electronic properties, and first and second harmonic generation for CdX compounds with zinc-blende structure performed using the full potential linearized augmented plane wave method. Our calculations show that these compounds have similar structures. The valence band maximum and the conduction band minimum are located at Γ, resulting in a direct energy gap. The energy gap of these compounds decreases when S is replaced by Se and Se by Te, in agreement with the experimental data and previous theoretical work. This can be attributed to the increase in the bandwidth of the conduction bands. The optical spectra are analyzed and the origin of some of the peaks in the spectra is discussed in terms of the calculated electronic structure. Our calculations for the linear optical properties show excellent agreement with the available experimental data.
Charging and spin-polarization effects in InAs quantum dots under bipolar carrier injection
Authors: Savelyev A. V. , Tartakovskii A. I. , Skolnick M. S. , Mowbray D. J. , Maximov M. V. , Ustinov V. M. , Seisyan R. P.
Published: March 2006

Carrier dynamics in quantum dot p-i-n diodes are studied using an ultrafast polarization-resolved pump-probe technique. It is demonstrated that for bipolar electrical injection there is a high probability of the independent capture of electrons or holes into the dots, resulting in dot charging. Voltage control of the charged exciton population, created via a combination of electrical and optical excitation, which exhibits a long lived spin polarization (or spin memory) is demonstrated.
On achieving better uniform carbon nanotube field emission by electrical treatment and the underlying mechanism
Authors: Liang X. H. , Deng S. Z. , Xu N. S. , Chen Jun , Huang N. Y. , She J. C.
Published: March 2006

The uniformity in field emission from a carbon nanotube film is very important to many applications. A study has been carried out to obtain uniform emission from multiwall carbon nanotube (CNT) films by electrical treatment. The electrical treatment is based on local vacuum breakdown of CNTs under direct-current conditions. The optimal current density was found, under which the best effect of the treatment may be observed. The physical mechanism responsible for the effect of local vacuum breakdown of CNTs on emission uniformity was investigated.
Bonding and excitation in CO∕Cu(001) from a cluster model and density functional treatments
Authors: Sudhyadhom Atchar , Micha David A.
Published: March 2006

The bonding properties and charge distributions of the CO∕Cu(001) system have been studied within density functional theory (DFT) with several density functionals. A Cu18(9,4,5)CO three layer cluster was found to give bond distances and energies in agreement with previous experimental and theoretical results for low coverage systems, provided the atomic basis set includes diffuse orbitals and d-orbitals at the Cu atoms. Charge distributions give insight on the nature of the localized adsorbate bonding. Time-dependent DFT results on excitation energies and on transition and average electric dipoles, relevant to photodesorption, are also presented.
Photonic band gap control in one-dimensional dielectric Bragg structures
Authors: Konoplev I. V. , Doherty G. , Cross A. W. , Phelps A. D. R. , Ronald K.
Published: March 2006

One-dimensional photonic band gap structures have been studied for applications in many branches of physics. Numerical and experimental studies of wave scattering and interference inside one-dimensional photonic band gap structures based on a rectangular waveguide filled with a double-sided corrugated dielectric are presented. The experimental data and theoretical predictions obtained are compared and discussed. It is shown experimentally that variation of the relative phase of the one-dimensional perturbations with respect to each other results in a change of the band gap parameters in accordance with the predictions.
Organic oxide/Al composite cathode in efficient polymer light-emitting diodes
Authors: Guo Tzung-Fang , Yang Fuh-Shun , Tsai Zen-Jay , Wen Ten-Chin , Hsieh Sung-Nien , Fu Yaw-Shyan , Chung Chia-Tin
Published: March 2006

This work presents the fabrication of efficient polymer light-emitting diodes (PLEDs) by thermally evaporating a salt-free neutral organic-oxide buffer layer onto the surface of the electroluminescent film in a vacuum before the device cathode, made of Al—rather than the low work function metals, such as Ca or Ba—is deposited. The electroluminescence (EL) efficiency of phenyl-substituted poly(para-phenylene vinylene) copolymer-based PLEDs with an organic oxide/Al composite cathode, reaches 8.86cd∕A, which is markedly higher than those, 5.26cd∕A and 0.11cd∕A, of devices with Ca∕Al and Al cathodes, respectively. The device performance is improved by the formation of a specific organic oxide/Al complex at the cathode interface during the deposition of Al, facilitating the injection of electrons and eliminating the metal-induced quenching sites of luminescence in the EL layer near the recombination region.
Guided wave sensing of polyelectrolyte multilayers
Authors: Horvath Robert , Pedersen Henrik C. , Cuisinier Frédéric J. G.
Published: March 2006

A planar optical waveguide configuration is proposed to monitor the buildup of thick polyelectrolyte multilayers on the surface of the waveguide in aqueous solutions. Instead of detecting the layer by the electromagnetic evanescent field the polyelectrolyte layer acts as an additional waveguiding film that is sensed by guided waves instead of evanescent waves. This leads to a considerably improved sensitivity and dynamic range.
High-power GaN-based blue-violet laser diodes with AlGaN∕GaN multiquantum barriers
Authors: Lee Sung-Nam , Cho S. Y. , Ryu H. Y. , Son J. K. , Paek H. S. , Sakong T. , Jang T. , Choi K. K. , Ha K. H. , Yang M. H. , Nam O. H. , Park Y. , Yoon E.
Published: March 2006

AlGaN ∕ GaN multiquantum barriers (MQBs) were introduced into violet AlInGaN laser diodes with an InGaN multiquantum-well structure, resulting in drastic improvements in lasing performance. Comparing with conventional AlGaN single electron blocking layer (EBL), lower threshold current of 32mA and higher slope efficiency of 1.12W∕A at room temperature has been achieved by using the AlGaN∕GaN multiquantum barrier. This improvement implies that p-type AlGaN∕GaN MQBs are more effective in suppressing the overflow of electrons than p-type AlGaN single EBL. Effective barrier heights of the MQBs should be higher than the single EBL due to the quantum effect of MQBs and the enhancement of p-type doping efficiency. Additionally, the effect of strain on InGaN multiquantum wells from the single EBL can be reduced by using the AlGaN∕GaN MQBs structure.
ZnTe
:
O
phosphor development for x-ray imaging applications
Authors: Kang Z. T. , Summers C. J. , Menkara H. , Wagner B. K. , Durst R. , Diawara Y. , Mednikova G. , Thorson T.
Published: March 2006

An efficient ZnTe:O x-ray powder phosphor was prepared by a dry synthesis process using gaseous doping and etching medias. The x-ray luminescent properties were evaluated and compared to standard commercial phosphors exhibited an x-ray luminescent efficiency equivalent to 76% of Gd2O2S:Tb and an equal resolution of 2.5lines∕mm. In addition, the fast decay time, low afterglow, and superior spectral match to conventional charge-coupled devices-indicate that ZnTe:O is a very promising phosphor candidate for x-ray imaging applications.
Memory effect of ZnO nanocrystals embedded in an insulating polyimide layer
Authors: Jung J. H. , Jin J. Y. , Lee I. , Kim T. W. , Roh H. G. , Kim Y.-H.
Published: March 2006

The memory effects of ZnO nanoparticles embedded in a polyimide (PI) matrix were investigated. Transmission electron microscopy images and selected area electron diffraction patterns showed that ZnO nanocrystals were created inside the PI layer. Capacitance-voltage (C-V) measurements on Al/PI/nanocrystalline ZnO∕PI∕p-Si structures at 300K showed a metal-insulator-semiconductor behavior with a flatband voltage shift due to the existence of the ZnO nanocrystals, indicative of trapping, storing, and emission in the electrons in the ZnO nanocrystals. Possible electronic structures corresponding to the writing and erasing operations for the Al/PI/nanocrystalline ZnO∕PI∕p-Si device are described on the basis of the C-V results.
Effect of defects on resonance of carbon nanotubes as mass sensors
Authors: Wang M. , Zhang X. , Lu M. W. , Liu Y.
Published: March 2006

The mass sensors based on carbon nanotubes (CNTs), especially one with uniform structure, have ultrahigh sensitivities. However, in application the CNTs’ properties will be affected by many factors such as volume defects or uneven mass repartition. In this letter, modified beam models are presented based on the Euler–Bernoulli beam theory to analyze the effect of the unideal structure on resonance frequency of CNTs themselves and as mass sensors. It can be found that the resonance frequency shift due to the defect is sensitive to the defect’s relative position on the CNT.
Optical waveguide fabrication in z-cut lithium niobate (LiNbO3) using femtosecond pulses in the low repetition rate regime
Authors: Thomson R. R. , Campbell S. , Blewett I. J. , Kar A. K. , Reid D. T.
Published: March 2006

Waveguide structures are fabricated in z-cut lithium niobate (LiNbO3) using focussed femtosecond pulses. Two different types of waveguide structure are fabricated depending on the pulse energy used. In the first, guiding occurs in regions directly surrounding a visible laser-damage region. In the second, guiding occurs in a material modification region created at the focus. High confinement guiding at 1550nm is demonstrated in the first type of waveguide but found to be temporary, thus indicating that at least part of the refractive index change is due to phenomena such as stress that are subject to relaxation. Finally, the polarization dependent guiding properties of the structures are investigated.
High-density electrostatic carrier doping in organic single-crystal transistors with polymer gel electrolyte
Authors: Takeya J. , Yamada K. , Hara K. , Shigeto K. , Tsukagoshi K. , Ikehata S. , Aoyagi Y.
Published: March 2006

High-density carrier accumulation in organic semiconductors is demonstrated in Au∕polymer gel electrolyte/rubrene crystal∕SiO2∕doped Si dual-gate transistors, forming electric double layers in the polymer gel. Application of only 1.2V across the polymer gel electrolyte drastically enhances the conductance of the rubrene single crystal with the field-induced carrier density up to ∼5×1013cm−2. Directly comparing the transfer characteristics of the same device channel in the dual-gate transistors revealed that the achieved doping level is beyond the maximum of the SiO2-based transistor on the opposite side of the organic crystal.
p
-type behavior from Sb-doped ZnO heterojunction photodiodes
Authors: Mandalapu L. J. , Xiu F. X. , Yang Z. , Zhao D. T. , Liu J. L.
Published: March 2006

Antimony (Sb) doping was used to realize p-type ZnO films on n-Si (100) substrates by molecular beam epitaxy. These samples were fabricated into p-n heterojunction diodes. p-type behavior of Sb-doped ZnO was studied by carrying out I-V and capacitance-voltage (C-V) measurements. I-V curves showed rectifying behavior similar to a p-type Schottky diode with a turn-on voltage around 2.4V, which is consistent with the Schottky barrier of about 2.2V obtained from C-V characterization. Good photoresponse in the UV region was obtained, which further proved that Sb doping could be used to fabricate p-type ZnO for photodetector and other optoelectronic applications.
Trophic relationships between itinerant fish and crab larvae in a temperate Australian saltmarsh
Authors: Mazumder Debashish , Saintilan Neil , Williams Robert J.
Published: March 2006

Comparisons of zooplankton inputs and outputs for a temperate Australian saltmarsh demonstrate a substantial contribution of crab larvae to the ebbing tide water, particularly during the cooler months. Few crab larvae were present in the incoming tide (mean abundance 4 m−3), whereas many crab larvae were present in the outgoing water (mean abundance 2124.63 m−3). Stomach content analysis of itinerant fish exiting the saltmarsh with the ebbing tide demonstrated extremely high proportions of crab larvae in the gut of glassfish (Ambassis jacksoniensis), as well as flat tail mullet (Liza argentea) and blue eye (Pseudomugil signifer). The results suggest a direct trophic link between secondary production of saltmarsh and itinerant fish, and a significant ecological role for burrowing crabs occupying saltmarshes in temperate Australia in the trophic food web of saltmarsh–estuarine systems.
Intraspecific interference in a tropical stream shredder guild
Authors: Boyero Luz , Pearson Richard G.
Published: March 2006

The structure of stream communities is typically thought to be driven by stochastic events such as floods, in contrast with communities in many other systems in which biotic interactions have a major role. However, it is possible that biotic interactions are important in some situations in streams, especially where resources are limited and physical influences are stable for substantial periods. Leaf litter – the main energy source and a distinct habitat in forest streams – constitutes a patchy resource where biotic interactions among and within consumer species are likely to occur. The intraspecific interference in four leaf-eating species (shredders), common in Australian tropical streams, was experimentally examined – Anisocentropus kirramus (Trichoptera : Calamoceratidae), Lectrides varians and Triplectides gonetalus (Trichoptera : Leptoceridae) and Atalophlebia sp. (Ephemeroptera : Leptophlebiidae). All four species showed some degree of intraspecific interference, indicated by lowered leaf breakdown rates when density increased. Breakdown rates per capita decreased exponentially for all species with increased density, with slight differences among species. These differences were more evident when body size was taken into account, with breakdown rates depressed at lower densities for the two species with larger body sizes, T. gonetalus and Atalophlebia sp. Overall breakdown rates did not always increase with higher densities, because they were compensated for by depressed individual breakdown rates. Our results indicate that intraspecific interference can be an important mechanism regulating leaf breakdown in streams.
Effects of Lyngbya majuscula (Cyanophycea) blooms on sediment nutrients and meiofaunal assemblages in seagrass beds in Moreton Bay, Australia
Authors: García Rosa , Johnstone Ron W.
Published: March 2006

Blooms of Lyngbya majuscula have been increasingly recorded in the waters of Moreton Bay, on the south-east coast of Queensland, Australia. The influences of these blooms on sediment infauna and the implications for sediment biogeochemical processes was studied. Sediment samples were taken from Moreton Bay banks during and after the bloom season. The deposition of L. majuscula seems to be responsible for the higher total Kjedahl nitrogen (TKN) concentrations measured during the bloom period. Total organic carbon (TOC) concentrations did not change. Lyngbya majuscula blooms had a marked influence on the meiobenthos. Nematodes, copepods and polychaetes were the most abundant groups of meiofauna, and the bloom produced a decrease in the abundance and a change in the sediment depth distribution of these organisms. The distribution of nematodes, copepods and polychaetes in sediment became shallower. Further, the bloom did not affect the abundance and distribution of polychaetes as strongly as it did copepods and nematodes. The changes observed in the distribution of meiofauna in the sediment during the bloom period indicate that L. majuscula produces oxygen depletion in sediments, and that different fauna seem to be affected to different degrees.
Differential response of stream periphyton and invertebrate grazers to habitat modification by the emergent macrophyte Justicia americana
Authors: Fritz Ken M. , Feminella Jack W.
Published: March 2006

An instream experiment was conducted using artificial substrate tiles during summer to examine the relative importance of shading by the emergent macrophyte Justicia americana and top-down control by stream grazers on summer periphyton accrual. Macrophyte treatments included removal of above-ground stems, removal of stems and rhizomes and an unmanipulated control, whereas grazer treatments included snail-accessible and snail-exclusion tiles. Above-ground Justicia structures reduced both sunlight to the stream bed and velocity by almost 50%. Abundance of the dominant snail, Elimia ucheensis (Pleuroceridae), on snail-exclusion tiles was significantly lower than on snail-accessible tiles only during the first week of the experiment; therefore, the barriers were ineffective over the entire experiment. Despite ineffective reductions of Elimia abundance over the entire experiment, periphyton accrual was higher on snail-exclusion than snail-accessible tiles irrespective of macrophyte treatment. Among the macrophyte treatments, periphyton biomass (as ash-free dry mass) was significantly lower on tiles in the unmanipulated control than treatments where Justicia stems were removed. Higher mean differences and relative magnitude of effects were associated with the macrophyte treatments when compared with the grazer treatments. Periphyton appeared to be primarily light-limited by Justicia and secondarily controlled by grazing invertebrates; however, the effects of grazing may have been underestimated because snail-exclusion barriers were ineffective at reducing grazer abundance over the experiment. Removal of Justicia canopy did not result in higher abundance of any invertebrate grazers on tiles; however, the abundance of the freshwater limpet (Ferrissia mcneili) was twice as high on tiles within the more shaded Justicia control sections compared with either of the two open-canopy treatments. Habitat modification by Justicia can negatively affect benthic primary producers and influence the distribution of some, but not all, primary consumers.
Molecular basis for the preferential cleft recognition by dromedary heavy-chain antibodies
Authors: De Genst Erwin , Silence Karen , Decanniere Klaas , Conrath Katja , Loris Remy , Kinne Jörg , Muyldermans Serge , Wyns Lode
Published: March 2006

Clefts on protein surfaces are avoided by antigen-combining sites of conventional antibodies, in contrast to heavy-chain antibodies (HCAbs) of camelids that seem to be attracted by enzymes’ substrate pockets. The explanation for this pronounced preference of HCAbs was investigated. Eight single domain antigen-binding fragments of HCAbs (VHH) with nanomolar affinities for lysozyme were isolated from three immunized dromedaries. Six of eight VHHs compete with small lysozyme inhibitors. This ratio of active site binders is also found within the VHH pool derived from polyclonal HCAbs purified from the serum of the immunized dromedary. The crystal structures of six VHHs in complex with lysozyme and their interaction surfaces were compared to those of conventional antibodies with the same antigen. The interface sizes of VHH and conventional antibodies to lysozyme are very similar as well as the number and chemical nature of the contacts. The main difference comes from the compact prolate shape of VHH that presents a large convex paratope, predominantly formed by the H3 loop and interacting, although with different structures, into the concave lysozyme substrate-binding pocket. Therefore, a single domain antigen-combining site has a clear structural advantage over a conventional dimeric format for targeting clefts on antigenic surfaces.
Strength of early visual adaptation depends on visual awareness
Authors: Blake Randolph , Tadin Duje , Sobel Kenith V. , Raissian Tony A. , Chong Sang Chul
Published: March 2006

We measured visual-adaptation strength under variations in visual awareness by manipulating phenomenal invisibility of adapting stimuli using binocular rivalry and visual crowding. Results showed that the threshold-elevation aftereffect and the translational motion aftereffect were reduced substantially during binocular rivalry and crowding. Importantly, aftereffect reduction was correlated with the proportion of time that the adapting stimulus was removed from visual awareness. These findings indicate that the neural events that underlie both rivalry and crowding are inaugurated at an early stage of visual processing, because both the threshold-elevation aftereffect and translational motion aftereffect arise, at least in part, from adaptation at the earliest stages of cortical processing. Also, our findings make it necessary to reinterpret previous studies whose results were construed as psychophysical evidence against the direct role of neurons in the primary visual cortex in visual awareness.
On the existence and scaling of structure functions in turbulence according to the data
Authors: Arenas Alexandre , Chorin Alexandre J.
Published: March 2006

We sample a velocity field that has an inertial spectrum and a skewness that matches experimental data. In particular, we compute a self-consistent correction to the Kolmogorov exponent and find that for our model it is zero. We find that the higher-order structure functions diverge for orders larger than a certain threshold, as theorized in some recent work. The significance of the results for the statistical theory of homogeneous turbulence is reviewed.
Waiting times for primary care psychological therapy and counselling services
Authors: Trusler Karen , Doherty Clare , Mullin Tracy , Grant Stewart , McBride Jenny
Published: March 2006

Waiting times for primary care psychological therapy and counselling are an increasingly important area by which the effectiveness of service delivery is measured. Authorities and advisory bodies advocate a reduction in waiting times and improvements in waiting list management (Department of Health, 1999, 2001, 2004; Healthcare Commission, 2005a; Health and Social Care Advisory Service, 2002). Research and practice both report large variations and inconsistencies in service waiting times. This paper uses the CORE National Research Database for Primary Care Psychological Therapies and Counselling (valid = 31882 clients) to develop benchmarks that services can use to measure their performance at a national level. Three time frames are analysed: Referral to first assessment, last assessment to first therapy, and referral to first therapy. The average waiting times were 8 weeks, 2 weeks, and 10 weeks respectively. The practical use of, and implications for these benchmarks within and between services and practitioners are explored by managers of primary care psychological therapy and counselling services. The discussion explores the significance of the benchmarks in relation to both political agendas and overall service performance. Initiatives to reduce waiting times and factors that may effect them are also discussed.
Routine outcome measurement completion rates of the CORE‐OM in primary care psychological therapies and counselling
Authors: Bewick Bridgette M. , Trusler Karen , Mullin Tracy , Grant Stewart , Mothersole Geoff
Published: March 2006

Formally evaluating and reporting on the progress of clients is now seen as a central component of clinical practice. Generally, research suggests that the percentage of practitioners who use outcome measures as part of their clinical practice is relatively low. However, no national benchmarks have yet been presented which allow both practitioners and services to assess their relative performance in terms of data collection. The present study uses the CORE National Research database (n=31882) and reports pre‐ and post‐therapy assessment completion rates, thereby enabling services to track their performance relative to other services. On average, pre‐therapy CORE‐OMs were reliably completed by 83% of clients while post‐therapy forms were completed by 39%. However, there were large variations between services. The practical use and implications of the results presented are discussed by managers of NHS primary care counselling services.
Risk Factors ForStenotrophomonas MaltophiliaBacteremia In Oncology Patients: A Case–Control Study
Authors: Apisarnthanarak Anucha , Mayfield Jennie L. , Garison Teresa , McLendon Patricia M. , DiPersio John F. , Fraser Victoria J. , Polish Louis B.
Published: March 2006

Objective:

To characterize risk factors forStenotrophomonas maltophiliabloodstream infection in oncology patients.

Design:

A 3:1 case–control study.

Setting:

Stem Cell Transplant and Leukemic Center at Barnes–Jewish Hospital (St. Louis), a 1,442-bed, tertiary-care teaching hospital with a 26-bed transplantation ward.

Method:

From June 1999 to April 2001,13 patients withS. maltophiliabacteremia were compared with 39 control-patients who were on the transplantation unit on the same day as the case-patients' positive blood cultures. Information collected included patient demographics, medical history, history of transplantation, transplantation type, graft versus host disease, neutropenia, antibiotic use, chemotherapy, mucositis, diarrhea, the presence of central venous catheter(s), cultures, and concomitant infections.

Results:

Significant risk factors forS. maltophiliabacteremia included severe mucositis (7 [53.8%] of 13 vs 8 [20.5%] of 39;P= .034), diarrhea (7 [53.8%] of 13 vs 8 [20%] of 39;P= .034), and the use of metronidazole (9 [69.2%] of 13 vs 8 [20.5%] of 39;P= .002). In addition, the number of antibiotics used (median, 9 vs 5;P< .001), duration of mucositis (median, 29 vs 15 days;P= .032), and length of hospital stay (median, 34 vs 22 days;P= .017) were significantly different between case- and control-patients. NineS. maltophiliaisolates tested by pulsed-field gel electrophoresis were found to be distinctly different.

Conclusion:

Interventions to ameliorate the severity of mucositis, reduce antibiotic pressure, prevent diarrhea, and promote meticulous central venous catheter care may help preventS. maltophiliabloodstream infection in oncology patients. The role of gastrointestinal tract colonization as a potential source ofS. maltophiliabacteremia in oncology patients deserves further investigation.
Infection Control in British Nursing Homes
Authors: Mayon-White Richard , Grant-Casey John
Published: March 2006

Infection control in British nursing homes is different from that in U.S. nursing homes in several ways. Most British nursing homes, for example, do not have a designated on-site infection control nurse, and several agencies are responsible for regulatory oversight. This article discusses the state of infection control in British nursing homes.