bluuebunny/crossref_metadata_2025 huggingface dataset:
NEW TAXA AND LECTOTYPIFICATIONS OF PEDICULARIS (OROBANCHACEAE) REQUIRED FOR THE FLORA OF PAKISTAN
Authors: Mill R. R.
Published: May 2010

The new taxa Pedicularis L. series Bicornutae R.R.Mill, Pedicularis series Rhynchotrichae R.R.Mill, Pedicularis bicornuta Klotzsch var. adenocalyx R.R.Mill, Pedicularis murreeana R.R.Mill & R.Bone and Pedicularis staintonii R.R.Mill (Orobanchaceae) are described. Pedicularis series Klotzschianae R.R.Mill is proposed as a replacement name for the illegitimate Pedicularis [unranked] Macranthae that has often been treated as ‘series Macranthae Prain’. The new combination Pedicularis bipinnatifida (Pennell) R.R.Mill is made and four names are lectotypified. An epitype is designated for Pedicularis bicornuta.
Guest Editorial: Ignoring the Social and Cultural Context of Bioethics Is Unacceptable
Authors: FOX RENÉE C. , SWAZEY JUDITH P.
Published: May 2010

To quote Yogi Berra, writing this editorial is a “déja vu all over again” experience for us. It entails not only collaborating once more as coauthors but also reiterating some of the criticisms and concerns that have figured prominently in virtually all our previous publications about bioethics—most recently in our bookObserving Bioethics.
The Cultural Context of End-of-Life Ethics: A Comparison of Germany and Israel
Authors: SCHICKTANZ SILKE , RAZ AVIAD , SHALEV CARMEL
Published: May 2010

End-of-life (EoL) decisions concerning euthanasia, stopping life-support machines, or handling advance directives are very complex and highly disputed in industrialized, democratic countries. A main controversy is how to balance the patient’s autonomy and right to self-determination with the doctor’s duty to save life and the value of life as such. These EoL dilemmas are closely linked to legal, medical, religious, and bioethical discourses. In this paper, we examine and deconstruct these linkages in Germany and Israel, moving beyond one-dimensional constructions of ethical statements as “social facts” to their conflicting and multifaceted embedding within professional, religious, and cultural perspectives.
CQ Sources/Bibliography
Authors: Anton Bette
Published: May 2010

These CQ Sources were compiled by Bette Anton.
In Situ Transmission Electron Microscopy Studies of the
Magnetization Reversal Mechanism in Information Storage Materials
Authors: Petford-Long Amanda K. , Portier Xavier , Bayle-Guillemaud Pascale , Anthony Thomas C. , Brug James A.
Published: May 2010

The Foucault and Fresnel modes of Lorentz microscopy, together with a
quantitative magnetization mapping technique, summed image differential
phase-contrast imaging, were used to study the magnetization reversal
mechanism of the sense layer in spin-valve structures exhibiting the giant
magnetoresistance effect. In addition to studies of sheet film,
lithographically defined spin-valve elements were investigated. A current
can be passed through the element during magnetizing so that the effect of
the applied current on the giant magnetoresistance and magnetization
reversal mechanism can be studied. Results are presented for a number of
different spin-valve structures.
Diagonal quartic surfaces and transcendental elements of the Brauer group
Authors: Ieronymou Evis
Published: May 2010

We exhibit central simple algebras over the function field of a diagonal quartic surface over the complex numbers that represent the 2-torsion part of its Brauer group. We investigate whether the 2-primary part of the Brauer group of a diagonal quartic surface over a number field is algebraic and give sufficient conditions for this to be the case. In the last section we give an obstruction to weak approximation due to a transcendental class on a specific diagonal quartic surface, an obstruction which cannot be explained by the algebraic Brauer group which in this case is just the constant algebras.
Eisenmangel und Eisenmangelanämie – Klinik und Therapie
Authors: Brunner Christian , Wuillemin Walter A.
Published: May 2010

Über einen sich selbstregulierenden Mechanismus wird Eisen resorbiert und in die Kompartimente Speicher-, Transport- und Funktionseisen verteilt. Einen geregelten Mechanismus zur Ausscheidung von Eisen gibt es nicht. Der Eisenhaushalt kann durch eine gestörte Aufnahme, einen erhöhten Bedarf oder einen Blutverlust aus dem Gleichgewicht gebracht werden. Die Ursache des Eisenmangels muss immer gesucht werden. Der zentrale diagnostische Eisen-Parameter ist das Ferritin. Eisen stellt ein wichtiges Spurenelement in zentralen Stoffwechselprozessen des Körpers dar und führt dadurch bei einem Mangel zu verschiedenen Symptomen, die zusätzlich von den Eisenmangel verursachenden Erkrankungen überlagert werden können. Die Symptome sind vielfältig und reichen von unspezifischen Beschwerden wie z. B. Müdigkeit und Konzentrationsschwäche bis zur Anämie. Entsprechend einer allfälligen Anämie und des geschätzten Eisenmangels kann die zu substituierende Eisenmenge errechnet und peroral oder, bei entsprechender Indikation, intravenös verabreicht werden.
Anämie bei Knochenmarksaplasie, paroxysmaler nächtlicher Hämoglobinurie und Myelodysplastischen Syndromen
Authors: Passweg Jakob R.
Published: May 2010

Es werden die Krankheitsbilder der aplastischen Anämie (AA), der paroxysmalen nächtlichen Hämoglobinurie (PNH) und des Myelodysplastischen Syndroms (MDS) diskutiert mit besonderer Beachtung der Probleme, die mit der Anämie bei diesen Erkrankungen assoziiert sind. Die Anämie bei AA und MDS sind auf die defiziente Erythropoese bei der PNH auf die Hämolyse zurückzuführen. Diskutiert werden die Transfusionsindikationen sowie der Einsatz von Wachstumsfaktoren, der Eisenchelatoren sowie weiterer spezifischer Therapien.
Medikamentöse Nicht-Adhärenz – Prädiktive Faktoren und Diagnostik
Authors: Schäfer-Keller Petra , Garzoni Daniela , Dickenmann Michael , De Geest Sabina
Published: May 2010

Gründe für medikamentöse Nicht-Adhärenz sind vielfältig und komplex. Es gibt derzeit keinen etablierten Goldstandard zur Erfassung von Nicht-Adhärenz. Wir stellen mit Nicht-Adhärenz verbundene Faktoren anhand von fünf Adhärenz-Dimensionen und anhand des subjektiven Bewertungsprozesses von Patienten vor. Basierend auf der aktuellen Evidenzlage empfehlen wir folgende zweistufige Adhärenz-Abklärung für die Klinik: 1) routinemäßige Adhärenz-Abklärung anhand des Patienten-Selbstberichts ergänzt mit Hinweisen auf Nicht-Adhärenz aus weiteren Quellen; 2) vertiefte Adhärenz-Abklärung für Patienten mit positivem Hinweis auf Nicht-Adhärenz mittels Gespräch. Die Adhärenz-Abklärung geht dabei zur Adhärenz-Unterstützung über. Adhärenz ist das Ergebnis einer partnerschaftlichen Zusammenarbeit zwischen Patienten und dem Gesundheitspersonal. In komplexen Fällen ist sie als ein, in mehreren Etappen zu erreichendes Fernziel zu betrachten.
Risiken und Nebenwirkungen durch Non Compliance
Authors: Russmann Stefan , Curkovic Ivanka , Huber Martin
Published: May 2010

Non Compliance ist ein in der täglichen Praxis häufiges aber unterschätztes Problem, welches erhebliche Risiken, Nebenwirkungen und Kosten verursacht. Neben der fehlenden Einnahme mit entsprechendem Wirkungsverlust können auch andere Arten der Non Compliance unterschieden werden. Dazu gehören die Einnahme einer falschen Dosis oder zum falschen Zeitpunkt, mangelnde Beachtung von Interaktionen, eine zu kurze Therapiedauer, die Weiterführung der Therapie entgegen Empfehlung und bei nicht gegebener Indikation sowie in Eigenregie eingenommene Zusatzmedikation mit Interaktionspotential. Hieraus lasen sich eine Vielzahl von Risiken und Nebenwirkungen ableiten, wofür wir Beispiele aus dem klinischen Alltag und der Literatur präsentieren. Wichtige Elemente zur Prävention der Non Compliance sind deren Antizipation, Erkennung und geeignete Gegenmaßnahmen, welche auf die Pharmakotherapie selbst, den Patienten, und das Gesundheitssystem als Rahmen der Pharmakotherapie zielen. Im Zentrum steht dabei immer eine gute Kommunikation und ein zuverlässiges Vertrauensverhältnis zwischen Arzt und Patient. Eine wichtige ergänzende Rolle für die Verbesserung der Compliance könnten in Zukunft auch die elektronische Verschreibung und Kontrolle der Pharmakotherapie spielen.
Adherence in der Asthmatherapie
Authors: Leuppi Jörg D.
Published: May 2010

Ungenügende Medikamenten-Adherence ist ein nicht zu verachtendes Problem im Management von chronischem Asthma. Ungenügende Information, nicht erfüllte Erwartungen und Medikamentennebenwirkungen sind wichtige Faktoren, die zu einer ungenügenden Adherence führen können. Neben einer optimalen Patienteninformation und Schulung, der Verwendung von Aktionsplänen und somit auch Übertragung von Eigenverantwortung an den Patienten ist es wichtig, eine individuelle Asthmatherapie in Abhängigkeit von Krankheitsschweregrad und Kontrolle zu wählen. Je nach Erwartungen und Möglichkeiten des Patienten sollte ein so einfach wie mögliches Therapieregime gewählt und mittels regelmäßigen Arztkontrollen die Patientenerwartungen, das Krankheitswissen und die Inhalationstechniken überprüft werden. So können entsprechende Maßnahmen und Therapieanpassungen vorgeschlagen werden, was schließlich in einer erfolgreichen und auch kosteneffizienten Asthmatherapie münden kann.
Global observations of gravity waves from High Resolution Dynamics Limb Sounder temperature measurements: A yearlong record of temperature amplitude and vertical wavelength
Authors: Yan Xiuping , Arnold Neil , Remedios John
Published: May 2010

Global observations of gravity waves have been performed using the High Resolution Dynamics Limb Sounder (HIRDLS) temperature data. A background field that was derived by dynamically calculating 31 day (±15 day) means to block the stationary component and the slowly varying planetary‐scale waves, was first subtracted from the HIRDLS temperature measurements. An additional step was then taken to remove rapidly moving planetary‐scale waves by developing an along‐track temperature filter, which was created by averaging the profiles within a 1000 km along‐track window. Finally, each individual temperature perturbation vertical profile was analyzed using a fast Fourier transform to estimate gravity wave temperature amplitudes and vertical wavelengths. The investigation of the monthly mean gravity wave temperature amplitudes for the year 2006 found that gravity wave activity in the stratosphere is highly variable with season and can be very orographically dependent, especially in the winter extratropics. The monthly zonal means show that the peak vertical wavelengths correspond closely to the peak amplitudes. The increasing amplitudes and vertical wavelengths are faster and generated at lower altitudes in the winter extratropical and high‐latitude stratosphere than those in the summer tropical stratosphere. This is consistent with the lower source altitudes of orographic gravity waves in the extratropics and high latitudes and the higher source altitudes of convectively generated gravity waves in the tropics. Three cases were studied for the observed gravity waves over large mountain ranges using the European Centre for Medium‐Range Weather Forecasts wind data. Investigations of episodes of enhanced gravity wave activity over the southern Andes, the Cascade Range, and the Rockies in winter months of 2006 indicate that orographic gravity waves refract downwind from the mountains and propagate along the direction of the intense winds. By way of contrast, observations of gravity waves around the Himalayas show a strong relationship with the cyclones in that region.
Understanding the 17O excess glacial‐interglacial variations in Vostok precipitation
Authors: Risi Camille , Landais Amaelle , Bony Sandrine , Jouzel Jean , Masson‐Delmotte Valérie , Vimeux Françoise
Published: May 2010

Combined measurements of δ18O, δ17O, and δD in ice cores, leading to d excess and 17O excess, are expected to provide new constraints on the water cycle and past climates. We explore different processes, both in the source regions and during the poleward transport, that could explain the 17O excess increase by 20 per meg observed from the Last Glacial Maximum (LGM) to Early Holocene (EH) at the Vostok station. Using a single‐column model over tropical and subtropical oceans, we show that the relative humidity at the surface is the main factor controlling 17O excess in source regions. Then, using a Rayleigh‐type model, we show that the 17O excess signal from the source region is preserved in the polar snowfall, contrary to d excess. Evaporative recharge over mid and high latitudes and δ18O seasonality in polar regions can also affect the Vostok 17O excess but cannot account for most of the 20 per meg deglacial increase from LGM to EH. On the other hand, a decrease of the relative humidity at the surface (rhs) by 8 to 22% would explain the observed change in 17O excess. Such a change would not necessarily be incompatible with a nearly unchanged boundary layer relative humidity, if the surface thermodynamic disequilibrium decreased by 4°C. Such a change in rhs would affect source and polar temperatures reconstructions from δ18O and d excess measurements, strengthening the interest of 17O excess measurements to better constrain such changes.
Geophysical evolution of the Themis family parent body
Authors: Castillo‐Rogez Julie C. , Schmidt B. E.
Published: May 2010

We model the geophysical evolution of the Themis family parent body. This study is motivated by the recent detection of water ice at the surface of 24 Themis, the first detection of free water on the surface of an asteroid. The Themis family members display a variety of spectral properties and densities, a possible indication that their parent was differentiated at the time of break‐up. Differentiation of the parent body is better explained if it accreted as a mixture of ice within a few My after the production of CAIs. From these models we highlight a number of issues that provide a strong rationale for further ground‐based and future space exploration of that family.
Thermochemical pressurization of faults during coseismic slip
Authors: Brantut N. , Schubnel A. , Corvisier J. , Sarout J.
Published: May 2010

During earthquakes, frictional heating on the fault plane induces a temperature rise and thus a pore pressure rise, which is known as thermal pressurization (TP). Coseismic mineral dehydrations may occur because of this temperature increase and are included within the TP framework. Dehydrations are modeled as a source term for pore pressure because of the total volume change and as a sink term for temperature because they are endothermic. The reaction occurs within the slipping zone when a threshold temperature Ts is reached. Dehydration reaction kinetic is modeled using a first‐order reaction rate. Using energy and fluid mass conservation, we derive analytically the equations of evolution of pore pressure, temperature, and reaction extent in the undrained, adiabatic case using a constant reaction rate. We investigate the values of the kinetic rate constant required to produce a significant effect, which are much higher than laboratory data reported in the literature on clay, serpentine, and phyllosilicate dehydration. We show, however, that such high values can be reached if the temperature dependency of the rate constant is taken into account. Next, we include fluid and heat transport and use an Arrhenius law to calculate the rate constant as a function of temperature. The subsequent set of differential equations is then solved numerically. The main effect of dehydration reactions is an increase of pore pressure and a stabilization of the temperature during slip. We explore a wide range of parameters in order to determine in which cases dehydration can be considered as a nonnegligible process. For high‐permeability rocks (>10−18 m2) and when the amount of water that can be released is of the order of 10%, dehydration is an important mechanism as it delays the onset of melting, which would normally occur even within the TP framework. If the onset temperature is low compared to the initial temperature T0 (Ts − T0 ≲ 150°C), overpressure can occur. If the reactions are highly endothermic and if their kinetic is fast enough, frictional melting would not occur unless the dehydration reactions are completed within the slipping zone.
Modeling and forecasting climate variables using a physical‐statistical approach
Authors: Campbell Edward P. , Palmer Mark J.
Published: May 2010

In climatology it is common for studies to use either process models derived from physical principles or empirical models, which are rarely combined in any formal way. In part, this is because it is difficult to develop process models for climate variables such as monthly or seasonal rainfall that may be thought of as outputs from complex physical processes. Models for these so‐called climate outputs therefore typically use empirical methods, often incorporating modeled data as predictors. Our application is concerned with using simplified models of the El Niño‐Southern Oscillation to drive forecasts of climate outputs such as monthly rainfall in southeast Australia. We develop a method to couple an empirical model with a process model in a sequential formulation familiar in data assimilation. This allows us to model climate outputs directly, and it offers potential for building new seasonal forecasting approaches drawing on the strengths of both empirical and physical modeling. It is also easy to update the model as more data become available.
Influence of the external mixing state of atmospheric aerosol on derived CCN number concentrations
Authors: Wex H. , McFiggans G. , Henning S. , Stratmann F.
Published: May 2010

We derived the range of particle hygroscopicities (κ) that occurs in the atmosphere, based on literature data of measured hygroscopic growth or based on chemical composition. The derived κ‐values show that the atmospheric aerosol often is an external mixture with respect to hygroscopicity. Mean κ were derived for urban, rural, and marine aerosols for the different hygroscopic modes. Using these κ and exemplary particle number size distributions for the different aerosols, the number concentration of cloud condensation nuclei (NCCN) was derived for two cases, (1) accounting for the less hygroscopic fraction of particles and (2) assuming all particles to have κ of the more hygroscopic mode. NCCN derived from measured particle hygroscopicity is overestimated for case (2). Overestimation of NCCN is largest for fresh continental aerosol and less pronounced for marine aerosol. With κ derived from bulk aerosol composition data, only the hygroscopicity of more soluble aerosol particles is captured. Bulk or even size‐resolved composition data will be insufficient to predict NCCN under many conditions unless independent information about particle mixing state is available.
On seeding equatorial spread F: Circular gravity waves
Authors: Tsunoda Roland T.
Published: May 2010

A direct link appears to exist between gravity wave (GW) activity in the troposphere and plasma structure in the nighttime equatorial F layer during the solstices. This finding strongly favors a role being played by a neutral‐ion coupling process, which involves (1) a spatially‐varying dynamo current, generated in situ by a GW, and (2) perturbation transfer to the plasma by a polarization electric field. We show, for the first time, how two more of the puzzling features in observed plasma structure, referred to as equatorial spread F (ESF), can finally be explained, if we allow GWs to have circular, instead of plane, phase fronts. These features include (1) early appearance of large‐scale wave structure (LSWS) when the F layer is low, and (2) common appearances of a monochromatic LSWS with a long zonal wavelength.
Organometallic Chemistry
Authors: Moulton Benjamin E , Wright Dominic S , Patmore Nathan , Willans Charlotte E , Wheatley Andrew E H , Sella A , Humphrey M G , Kays Deborah , Liddle Stephen
Published: May 2010

Organometallic Chemistry is an interdisciplinary science which continues to grow at a rapid pace. Although there is continued interest in synthetic and structural studies, the last decade has seen a growing interest in the potential of organometallic chemistry to provide answers to problems in synthetic organic chemistry, the development of new materials and catalysis. This Specialist Periodical Report aims to reflect these current interests, and since Volume 34 provides both comprehensive and critical reviews of the recent literature. Topics examined in this volume include heterocyclic carbene compounds, coinage metals and paddlewheel compounds.
Non-transition metal N-heterocyclic carbene complexes
Authors: Willans Charlotte E.
Published: May 2010

Since their isolation in 1991,1 N-heterocyclic carbenes (NHCs) have become ubiquitous in organometallic chemistry. In more recent years investigations into the coordination of NHCs to other elements have expanded, and there are examples of their coordination to elements across the whole periodic table. This report gives an overview of NHC complexes of non-transition metal elements, ranging from the s-block elements, through the p-block and on to the lanthanides.
The Pauson-Khand reaction
Authors: Moulton Benjamin E.
Published: May 2010

The metal mediated synthesis of cyclopentenones via a [2+2+1] cycloaddition between an alkyne, an alkene and carbon monoxide has become commonly known as the Pauson-Khand (PK) reaction. This report will briefly summarise some of the major developments since its initial discovery including an intramolecular variant of the reaction, the progress made towards making the process catalytic and examples of how the reaction has been utilised. The proposed mechanism for the reaction and the factors that influence the product distribution will also be introduced.
Optimal composition of europium gallium oxide thin films for device applications
Authors: Wellenius P. , Smith E. R. , LeBoeuf S. M. , Everitt H. O. , Muth J. F.
Published: May 2010

Europium gallium oxide (EuxGa1-x)2O3 thin films were deposited on sapphire substrates by pulsed laser deposition with varying Eu content from x=2.4 to 20 mol %. The optical and physical effects of high europium concentration on these thin films were studied using photoluminescence (PL) spectroscopy, x-ray diffraction (XRD), and Rutherford backscattering spectrometry. PL spectra demonstrate that emission due to the D50 to F7J transitions in Eu3+ grows linearly with Eu content up to 10 mol %. Time-resolved PL indicates decay parameters remain similar for films with up to 10 mol % Eu. At 20 mol %, however, PL intensity decreases substantially and PL decay accelerates, indicative of parasitic energy transfer processes. XRD shows films to be polycrystalline and beta-phase for low Eu compositions. Increasing Eu content beyond 5 mol % does not continue to modify the film structure and thus, changes in PL spectra and decay cannot be attributed to structural changes in the host. These data indicate the optimal doping for optoelectronic devices based on (EuxGa1-x)2O3 thin films is between 5 and 10 mol %.
Spike morphology in blast-wave-driven instability experiments
Authors: Kuranz C. C. , Drake R. P. , Grosskopf M. J. , Fryxell B. , Budde A. , Hansen J. F. , Miles A. R. , Plewa T. , Hearn N. , Knauer J.
Published: May 2010

The laboratory experiments described in the present paper observe the blast-wave-driven Rayleigh–Taylor instability with three-dimensional (3D) initial conditions. About 5 kJ of energy from the Omega laser creates conditions similar to those of the He–H interface during the explosion phase of a supernova. The experimental target is a 150 μm thick plastic disk followed by a low-density foam. The plastic piece has an embedded, 3D perturbation. The basic structure of the pattern is two orthogonal sine waves where each sine wave has an amplitude of 2.5 μm and a wavelength of 71 μm. In some experiments, an additional wavelength is added to explore the interaction of modes. In experiments with 3D initial conditions the spike morphology differs from what has been observed in other Rayleigh–Taylor experiments and simulations. Under certain conditions, experimental radiographs show some mass extending from the interface to the shock front. Current simulations show neither the spike morphology nor the spike penetration observed in the experiments. The amount of mass reaching the shock front is analyzed and potential causes for the spike morphology and the spikes reaching the shock are discussed. One such hypothesis is that these phenomena may be caused by magnetic pressure, generated by an azimuthal magnetic field produced by the plasma dynamics.
Construction of pseudobosons systems
Authors: Bagarello F.
Published: May 2010

In a recent paper we have considered an explicit model of a PT-symmetric system based on a modification of the canonical commutation relation. We have introduced the so-called pseudobosons, and the role of Riesz bases in this context has been analyzed in detail. In this paper we consider a general construction of pseudobosons based on an explicit coordinate representation, extending what is usually done in ordinary supersymmetric quantum mechanics. We also discuss an example arising from a linear modification of standard creation and annihilation operators, and we analyze its connection with coherent states.
Comment on “Functional determinants in higher derivative Lagrangian theories” [J. Math. Phys. 50, 103517 (2009)]
Authors: Andrzejewski Krzysztof , Gonera Joanna , Maślanka Paweł
Published: May 2010

We comment on the recent paper of Di Criscienzo and Zerbini [J. Math. Phys. 50, 103517 (2009)]. We argue that the Euclidean evolution operator computed in our paper (K. Andrzejewski et al., e-print arXiv:0904.3055) is correct contrary to the claim of Di Criscienzo and Zerbini.
Stieltjes–Calogero–Gil’ relations associated to entire functions of finite order
Authors: Anghel N.
Published: May 2010

The classical Stieltjes–Calogero relations involving the zeros of the Hermite polynomials found over the years counterpart associated with virtually all the important polynomials appearing in mathematical physics. The standard method of deriving them typically rests on two different ways of looking at the Laurent expansion of the logarithmic derivative of a polynomial about a singular point, that is, a zero of the polynomial. While the first way is a straightforward formalism, the second proves to be cumbersome and is usually handled on a case by case basis, often based on Painlevé transcendent techniques, if the logarithmic derivative of the polynomial in question is solution to a suitable nonlinear differential equation. In this note we settle the problem completely and in full generality via an analysis based on Gil’s remarkable relations involving the zeros of an entire function of finite order. In addition to being elegant and efficient, the new method has wider applicability, addressing not just polynomials but also entire functions of finite order.
Enhanced resistance of single-layer graphene to ion bombardment
Authors: Lopez J. J. , Greer F. , Greer J. R.
Published: May 2010

We report that single-layer graphene on a SiO2/Si substrate withstands ion bombardment up to ∼7 times longer than expected when exposed to focused Ga+ ion beam. The exposure is performed in a dual beam scanning electron microscope/focused ion beam system at 30 kV accelerating voltage and 41 pA current. Ga+ ion flux is determined by sputtering a known volume of hydrogenated amorphous carbon film deposited via plasma-enhanced chemical vapor deposition.
Surface plasmon resonance and magneto-optical enhancement on Au–Co nanocomposite thin films
Authors: Yang K. , Clavero C. , Skuza J. R. , Varela M. , Lukaszew R. A.
Published: May 2010

We present our investigations on the enhancement of magneto-optical (MO) effects in nanocomposite Au–Co thin films. All the samples in this study were obtained by cosputter deposition varying the relative Au:Co composition and the growth temperature. A strong enhancement of the transverse MO activity is observed when surface plasmons are excited in the Kretschmann configuration. The correlation between the nanocomposite films' microstructure, morphology, composition, and their optical response under surface plasmon resonance excitation and their MO enhancement is discussed.
Trap states in AlGaN/GaN metal-oxide-semiconductor structures with Al2O3 prepared by atomic layer deposition
Authors: Gregušová D. , Stoklas R. , Mizue Ch. , Hori Y. , Novák J. , Hashizume T. , Kordoš P.
Published: May 2010

Atomic layer deposition (ALD) of Al2O3 was used to prepare metal-oxide-semiconductor (MOS) devices on two different_AlGaN/GaN heterostructures, with and without a thin GaN cap layer. Their trapping effects were evaluated by the frequency dependent conductance measurement. The trap state density decreased sharply from ∼1×1012 cm−2 eV−1 at the energy of 0.27 eV to ∼3×1010 cm−2 eV−1 at 0.45 eV. The low trap state density and exactly exponential dependence of the trap state time constant on the gate voltage show a good quality of the gate oxide. The trap state density in the structure with a GaN cap is about 2–3 times lower than that in the structure without a cap, which might be due to the different Al2O3/GaN and Al2O3/AlGaN interface properties. The trap state density in the structures investigated is lower than those reported for the devices with the metal-organic chemical vapor deposition and Al-oxidized Al2O3 gate oxide. This shows an importance of the ALD technique for the preparation of high-performance AlGaN/GaN MOS transistors.
Merging of shielded Gaussian vortices and formation of a tripole at low Reynolds numbers
Authors: Tóth Gábor , Házi Gábor
Published: May 2010

The interaction between two corotating shielded Gaussian vortices is studied by two-dimensional numerical simulations at low Reynolds numbers. It is shown that the outcome of the interactions can be a shielded monopole, a tripole, or dipolar breaking depending on the initial separation distance and Reynolds number. A flow regime map is given in the parameter space of initial separation distance and Reynolds number. Using formal decomposition for vorticity, we show that the tripole formation is due the same physical mechanism than merging of unshielded vortices, while in dipolar breaking both the symmetric and antisymmetric vorticity contributions play important role.
Influence of uniaxial mechanical stress on the high frequency performance of metal-oxide-semiconductor field effect transistors on (100) Si wafer
Authors: Han Younggun , Koganemaru Masaaki , Ikeda Toru , Miyazaki Noriyuki , Choi Woon , Tomokage Hajime
Published: May 2010

The effects of uniaxial mechanical stress on the radio frequency performance of n- and p-metal-oxide-semiconductor field effect transistors (MOSFETs) are investigated up to 10 GHz. Under tensile stress, the gate transconductance (gm) increases in the n-MOSFETs while it decreases in the p-MOSFETs, whereas the results were vice versa for compressive stress. The total gate capacitance (CG) extracted from scattering parameters increases (decreases) under tensile (compressive) stress for both n- and p-MOSFETs, which is explained by the variation in the effective mass perpendicular to the Si/SiO2 interface. The cut-off frequency (fT) varies in inverse proportion to the CG variation.
Accuracy and precision in photonic Doppler velocimetry
Authors: Dolan D. H.
Published: May 2010

While photonic Doppler velocimetry (PDV) is becoming a common diagnostic in dynamic compression research, its limiting accuracy and precision are not well understood. Velocity resolution is known to be inversely proportional to the time resolution, but resolution estimates differ by one to two orders of magnitude. Furthermore, resolution varies with the number of recorded signals and how these signals are analyzed. Numerical simulations reveal factors that affect accuracy and precision in PDV, and the results may be extended to a broad class of measurements. After systematic effects are eliminated, the limiting velocity uncertainty in a PDV measurement is governed by the sampling rate, the signal noise fraction, and the analysis time duration.
Electric-field effects on thickness dependent magnetic anisotropy of sputtered MgO/Co40Fe40B20/Ta structures
Authors: Endo M. , Kanai S. , Ikeda S. , Matsukura F. , Ohno H.
Published: May 2010

We have investigated the effect of applied electric field EG on thickness dependent magnetic anisotropy of sputtered Co40Fe40B20 sandwiched with MgO and Ta. The range of CoFeB thickness explored is 2 nm and below. As the thickness is reduced, the easy axis of magnetization becomes perpendicular from in-plane. We show that perpendicular magnetic anisotropy of in-plane samples and coercivity of perpendicular samples can be modified by applying EG at room temperature. Furthermore, superparamagnetic behavior is observed for CoFeB layers with further reduced thickness below ≈0.9 nm, where electric-field effect is also observed below their blocking temperature.
An amplified femtosecond laser system for material micro-/nanostructuring with an integrated Raman microscope
Authors: Zalloum Othman H. Y. , Parrish Matthew , Terekhov Alexander , Hofmeister William
Published: May 2010

In order to obtain new insights into laser-induced chemical material modifications, we introduce a novel combined approach of femtosecond pulsed laser-direct writing and in situ Raman microscopy within a single experimental apparatus. A newly developed scanning microscope, the first of its kind, provides a powerful tool for micro-/nanomachining and characterization of material properties and allows us to relate materials’ functionality with composition. We address the issues of light delivery to the photomodification site and show the versatility of the system using tight focusing. Amplified femtosecond pulses are generated by a Ti:sapphire laser oscillator and a chirped-pulse regenerative amplifier, both pumped by a diode-pumped frequency doubled neodymium-doped yttrium orthovanadate (Nd:YVO4) laser operating at 532 nm. Results of Raman spectroscopy and scanning electron microscopy images of femtosecond laser micro-/nanomachining on the surface and in the bulk of single-crystal diamond obtained from first trials of this instrument are also presented. This effective combination could help to shed light on the influence of the local structure fluctuations on controllability of the laser processing and the role of the irradiation in the ablation processes ruling out possible imprecisions coming from the use of the two independent techniques.
Dispersion measurements of a 1.3 μm quantum dot semiconductor optical amplifier over 120 nm of spectral bandwidth
Authors: Bagnell M. , Davila-Rodriguez J. , Ardey A. , Delfyett P. J.
Published: May 2010

Group delay and higher order dispersion measurements are conducted on a 1.3 μm quantum dot semiconductor optical amplifier at various injection currents. White-light spectral interferometry is performed, along with a wavelet transform to recover the group delay. The group delay, group velocity dispersion, and higher order dispersion terms are quantified. The measurement spans both ground state and first excited state transitions, ranging from 1200 to 1320 nm. The group velocity dispersion, β2, is found to be −6.3×103 fs2 (7.6 fs/nm) at an injection current of 500 mA.
Pressure, chaotic magnetic fields, and magnetohydrodynamic equilibria
Authors: Hudson S. R. , Nakajima N.
Published: May 2010

Analyses of plasma behavior often begin with a description of the ideal magnetohydrodynamic equilibrium, this being the simplest model capable of approximating macroscopic force balance. Ideal force balance is when the pressure gradient is supported by the Lorentz force, ∇p=j×B. We discuss the implications of allowing for a chaotic magnetic field on the solutions to this equation. We argue that the solutions are pathological and not suitable for numerical calculations. If the pressure and magnetic field are continuous, the only nontrivial solutions have an uncountable infinity of discontinuities in the pressure gradient and current. The problems arise from the arbitrarily small length scales in the structure of the field, and the consequence of ideal force balance that the pressure is constant along the field-lines, B⋅∇p=0. A simple method to ameliorate the singularities is to include a small but finite perpendicular diffusion. A self-consistent set of equilibrium equations is described, and some algorithmic approaches aimed at solving these equations are discussed.
Light-powered micromotor driven by geometry-assisted, asymmetric photon-heating and subsequent gas convection
Authors: Han Li-Hsin , Wu Shaomin , Condit J. Christopher , Kemp Nate J. , Milner Thomas E. , Feldman Marc D. , Chen Shaochen
Published: May 2010

We report on the design, fabrication, and analysis of a light-driven micromotor. The micromotor was created from a nanoporous polymer with close-packed gold nanoparticles which generate heat by absorbing light. The blades of the micromotor were curved, forming convex and concave sides. Upon lateral irradiation, by geometric effect the convex side transfers more photon-generated heat to the surrounding gas molecules, causing a convective motion of gas and leading to the rotation of the micromotor. The light-driven motions of gas molecules were analyzed using molecular dynamics modeling.
Improvement in the photon-induced bias stability of Al–Sn–Zn–In–O thin film transistors by adopting AlOx passivation layer
Authors: Yang Shinhyuk , Cho Doo-Hee , Ryu Min Ki , Park Sang-Hee Ko , Hwang Chi-Sun , Jang Jin , Jeong Jae Kyeong
Published: May 2010

This study examined the impact of the passivation layer on the light-enhanced bias instability of Al–Sn–Zn–In–O (AT–ZIO) thin film transistors. The suitably passivated device exhibited only a threshold voltage (Vth) shift of 0.72 V under light-illuminated negative-thermal stress conditions, whereas the device without a passivation layer suffered from a huge negative Vth shift of >11.5 V under identical conditions. The photocreated hole trapping model could not itself explain this behavior. Instead, the light-enhanced Vth instability of the unpassivated device would result mainly from the photodesorption of adsorbed oxygen ions after exposing the AT–ZIO back-surface in an ambient atmosphere.
Current-induced degradation of high performance deep ultraviolet light emitting diodes
Authors: Moe Craig G. , Reed Meredith L. , Garrett Gregory A. , Sampath Anand V. , Alexander Troy , Shen Hongen , Wraback Michael , Bilenko Yuriy , Shatalov Maxim , Yang Jinwei , Sun Wenhong , Deng Jianyu , Gaska Remis
Published: May 2010

Lifetime measurements on single-chip, packaged 285 nm light-emitting diodes (LEDs) performed under constant current injection at 20 and 75 mA, were compared to the performance of unbiased LEDs baked at the equivalent operating junction temperatures. The thermally stressed devices showed a lesser degradation than those electrically stressed, indicating that elevated temperature alone does not cause degradation. Despite a decay to less than half of the initial power under current injection, time-resolved photoluminescence of the active region exhibits little change, while capacitance-voltage measurements imply that the reduced efficiency and power decay originate from the generation of point defects near the p-side of the p-n junction.
Capacitance-voltage characteristics of SrTiO3/LaVO3 epitaxial heterostructures
Authors: Choi Woong , Lee Sang Yoon , Sands Timothy D.
Published: May 2010

We report a quantitative analysis on the capacitance-voltage (C-V) characteristics of metal-insulator-semiconductor capacitors based on SrTiO3/LaVO3 epitaxial heterostructures grown by pulsed laser deposition. The C-V measurement of the heterostructure exhibited a decrease in capacitance by ∼20% at positive voltages with an estimated carrier concentration of 8×1018 cm−3. The C-V curve by a simulation was in good agreement with the measurement, confirming the formation of a depletion layer and the estimated carrier concentration. These results suggest that quantitative understanding on the electrical behavior of oxide heterostructures is possible with C-V measurements, with potentially important implications on their device applications.
Perpendicular spin-torque switching with a synthetic antiferromagnetic reference layer
Authors: Tudosa Ioan , Katine J. A. , Mangin S. , Fullerton Eric E.
Published: May 2010

Spin-torque switching of perpendicular anisotropy nanopillar spin valve devices with synthetic antiferromagnetic reference layers is presented. The use of composite reference layer reduces the dipolar interaction with the free layer yielding two remanent states. We derive a complete current-field phase diagram including minor loops of the free layer where we determine the relative dipolar fields and effective spin polarization of the reference layer in both the parallel and antiparallel configurations. We find the magnetic response of the reference layer relatively insensitive to the spin polarized current which may prove advantageous for spin-torque applications.
Ultrahigh secondary electron emission of carbon nanotubes
Authors: Luo Jun , Warner Jamie H. , Feng Chaoqun , Yao Yagang , Jin Zhong , Wang Huiliang , Pan Caofeng , Wang Sheng , Yang Leijing , Li Yan , Zhang Jin , Watt Andrew A. R. , Peng Lian-mao , Zhu Jing , Briggs G. Andrew D.
Published: May 2010

The secondary electron emission of the tube bodies of single-walled carbon nanotubes is found to be ultrahigh and comparable with that of diamond, when the nanotubes are connected with electron reservoir. Both of semiconducting and metallic nanotubes possess this property.
Phosphorus sorption and desorption characteristics of wetland soils from a subtropical reservoir
Authors: Liu Wenzhi , Liu Guihua , Li Siyue , Zhang Quanfa
Published: May 2010

Water-level regulation results in alternating exposure and inundation of soils in reservoir fluctuation zones, which may significantly influence the phosphorus sorption and desorption processes in the soil. The present study investigated the phosphorus sorption and desorption properties of wetland soils in China's Danjiangkou Reservoir using a batch equilibrium technique. Results showed that the maximum phosphorus sorption ranged from 435 to 1429 mg kg−1, with an average of 771 mg kg−1. The maximum phosphorus sorption was found to be significantly related to amorphous iron (r = 0.883, P < 0.01) and pH (r = −0.333, P < 0.05), and the binding constant k was strongly correlated with the amorphous iron (r = 0.475, P < 0.01) and organic matter (r = −0.455, P < 0.01). The phosphorus desorption percentage varied from 8 to 44%, with a mean value of 24%. The present study implies that short-term inundation in reservoir fluctuation zones would result in soil phosphorus desorption to some extent, in spite of the considerable absorption ability in the exposure period. These results are useful for assessing the phosphorus retention capacity of wetland soils and optimising management strategies for water conservation in reservoir regions.
A Bayesian network model linking nutrient management actions in the Tully catchment (northern Queensland) with Great Barrier Reef condition
Authors: Shenton Will , Hart Barry T. , Brodie Jon
Published: May 2010

Correlating catchment management actions with improvements in the ecological condition of downstream coastal regions is challenging. We describe a Bayesian network (BN) model that predicts the effects of nitrogen-fertiliser management strategies in the Tully River catchment (northern Queensland) on the condition of inshore reefs of the Great Barrier Reef (GBR). The model consists of three linked submodels that relate sugarcane nitrogen management with runoff into the Tully River and nitrate concentration in the GBR lagoon, predicts phytoplankton biomass in the GBR lagoon from the nitrate inputs, and links the phytoplankton biomass with three marine influences to predict the probability of the reefs being dominated by coral (good) or macro-algae (bad). Four scenarios were modelled – current and the ‘six easy steps’ nitrogen management, and active and depleted algal grazing (herbivory) of the reef. The model predicts an increased probability of the reef being coral-dominated with current fertiliser practice and with active reef herbivory, with increased algal-dominance if reef herbivory is decreased. Introduction of a better nitrogen-fertiliser management with active herbivory resulted in an increased probability of coral dominance. This comparative-scenario analysis highlights the importance of both agricultural nutrient management practices and marine processes in predicting reef condition.
Calibration of a rapid non-lethal method to measure energetic status of a freshwater fish (Murray cod, Maccullochella peelii peelii)
Authors: Whiterod Nick S.
Published: May 2010

The energetic status of freshwater fish provides a dynamic measure of their energy balance in response to the environment they occupy. Commercially available microwave technology (the ‘energy meter’) provides a rapid, non-lethal and inexpensive alternative to traditional laboratory methods for the determination of energy density. The energy meter requires species-specific confirmation of the water–lipid relationship, and comparison of energy meter readings with laboratory-determined estimates of the whole-body energy density. I explored the applicability of the energy meter to the threatened Murray cod (Maccullochella peelii peelii), using both hatchery and wild individuals. Although hatchery and wild fish varied in lipid content, water content and energy density, the parameter comparisons necessary to calibrate the energy meter were statistically consistent between both groups. Subsequently, a robust combined water–lipid relationship was identified for Murray cod, where energy density was strongly related to both water content and lipid content. Average energy meter readings were capable of providing a rapid, non-lethal and accurate assessment of Murray cod energy density. The successful calibration highlights the applicability of the energy meter to provide a dynamic measure of the energetic status of threatened freshwater fish throughout the world.
Seasonal population dynamics of the non-native Caprella mutica (Crustacea, Amphipoda) on the west coast of Scotland
Authors: Ashton Gail V. , Burrows Michael T. , Willis Kate J. , Cook Elizabeth J.
Published: May 2010

Information on the life history and population dynamics of non-native species is essential to understand the process of invasion and impacts on invaded ecosystems. The non-native marine caprellid amphipod Caprella mutica has successfully established populations on coastlines throughout the temperate northern hemisphere and in New Zealand in the southern hemisphere. The introduction mechanism has been surpassed and it is now important to understand its ecology and biology in non-native habitats. The seasonal population dynamics of C. mutica were investigated over 18 months at four sites with different levels of anthropogenic disturbance on the west coast of Scotland. Abundance of C. mutica fluctuated seasonally at all sites, peaking during June to October. The highest abundance recorded on a single mesh collector was 319 000 individuals m−2 in August 2004 at one of the fish farms. Both seasonal and site-specific factors influenced the population dynamics of C. mutica. Both males and females were significantly larger and more abundant at the fish farm sites. Individuals displayed reproductive characteristics at a smaller size at the fish farm sites, indicating earlier maturity. The results suggest that anthropogenic disturbance and artificial resource enhancement contribute to the global establishment success of non-native C. mutica.