bluuebunny/crossref_metadata_2025 huggingface dataset:
A bibliography of planctus
Authors: Yearley Janthia
Published: July 2009

The present bibliography was originally compiled to provide a basis for my research into the relationship between words and music and the social context of the medieval European planctus. The planctus, a lament normally written at the death of an important historical, biblical or classical personage, or at the destruction of a city, has featured prominently in discussions about the development of liturgical drama and the possible origins of the Passion play; in studies of funeral verse; and in histories of the interrelation of European verse and musical forms. The relationship between the Marienklage and German Passion plays, the sequence and lai characteristics of Abelard's six planctus and the melodic style of the sequence melody planctus cygni have to some extent been studied by both musical and literary scholars. It has not, however, been possible to estimate the significance of these three issues in the history of either the planctus or of medieval monophonic song, since the planctus has never before been considered as a whole, in a comparative study which investigates both words and music. In fact, it has never been established that the planctus constitutes a genre in the first place, in what way this might be, and whether the surprisingly numerous musical settings which survive are composed in a consistent style.
The ordinary of mass chants and the sequences
Authors: Hiley David
Published: July 2009

Several writers – most notable among the recent ones being Max Lütolf, Rudolf Flotzinger and Edward Roesner – have commented on the choice of liturgical chants set in the additions to the main layer of Parisian polyphony in W1. The point of such comment is that by tracing concordances for those liturgical chants a clearer idea may be gained of the affiliations of W1 among the chant traditions of Britain and North France. The additions to W1 are more useful for this purpose than the main body of organa. The latter are settings of chants which were for the most part very widely known. Relatively few of them are unusual enough to permit speculation about the church for which W1 was compiled, or about the liturgical use to which it most nearly corresponds. So far as the organa are concerned, I do not feel that much advance can be made upon the careful discussion in Professor Roesner's article.
Melodic traditions in medieval English antiphoners
Authors: Underwood Peter J.
Published: July 2009

Thomas Cranmer's Preface to the 1549 Book of Common Prayer pointed out the “great diversity in saying and singing in churches within this realm”, and this comment was no less applicable to earlier medieval England, which presented a patchwork of some eight-hundred religious communities scattered throughout the country, working under various religious Rules, and often following diverse liturgies.
Some prosulas for offertory antiphons
Authors: Björkvall Gunilla , Steiner Ruth
Published: July 2009

This is a study of five offertory antiphons and the prosulas written to fit them (and in some cases to fit their verses as well). The original focus of the investigation was three of the prosulas written on the last folio of the 10th-century manuscript Apt, Basilique Sainte-Anne, 18 (shown on Plates 1 and 2). The study was then enlarged to bring in prosulas for two offertories whose melodies are similar to those first investigated. There is a special point in studying these particular compositions, since the four prosulas central to the discussion are rare examples of prosulas for the antiphon of the offertory, rather than its verse. But they are treated as broadly as possible in this paper, and made the subject of comment on the origin and nature of the base antiphon, its text and music, the function of the prosulas, the technique of their composition and the relationship between their text and their music. A critical edition and translation of each prosula is provided, and the first of these is preceded by a brief discussion of the problems of editing prosula texts. It is hoped that a fully rounded view will thereby be provided of the offertory antiphon and the prosula as a musical, literary and liturgical unit, and that fresh insights into their composition will be gained.
Ambrosian chant in southern Italy
Authors: Bailey Terence
Published: July 2009

A number of manuscripts from Southern Italy, almost all of them written in ‘Beneventan’ script and neumes, contain chants that are not the usual Gregorian assignments. These unusual chants have come generally to be known as Old Beneventan; in the manuscripts, however, a number of them are designated “Ambrosian”. That these chants are in any real sense Ambrosian has never been taken very seriously, even though there is very good evidence for doing so.
Introit antiphon paraphrase in the Trent Codices: Laurence Feininger'sconfronto
Authors: Fallows David
Published: July 2009

It is well known that when Father Laurence Feininger died in 1976 he left a substantial body of unpublished material. Edward Lowinsky has argued powerfully that “an enormous obligation rests on the national and international associations of musicology to undertake the publication of Feininger's scholarly estate and to bring it to the full use and enjoyment of the musical and musicological world”.
Tonaries and melodic families of antiphons
Authors: Merkley Paul
Published: July 2009

One theory of the origin, development and structure of the chant repertoire is that the thousands of individual pieces in it arose from the adaptation of new texts to a small number of melodies, or melodic ‘themes’. First put forward by Gevaert, this theory, which will be referred to here as the thematic theory, has, in different forms, been the basis of studies of the transmission of antiphons, and is now being applied to the repertories of Old-Roman and Ambrosian chant. The main demonstration of the validity of the theory must take place, of course, in studies of the repertoire itself; we shall be convinced if musical and liturgical evidence supports the idea of adaptation and suggests a chronological development. It is nevertheless important to examine music-historical witnesses ancillary to the chant repertoire, for it is often the case that related documents reveal something unexpected about the main repertoire, or serve as a means of confirming points for which evidence is lacking.
A MODEL FOR LOCKING IN GAINS WITH AN APPLICATION TO CLINICAL TRIALS
Authors: Ross Sheldon M. , Tijms Henk , Wu Shinyi
Published: July 2009

We consider a model in which each round consists of a sequence of games, with each game resulting in either a positive or a zero score. If a zero score occurs, then the current round is ended with no points being accumulated during that round. If a game ends with a positive score, then the player can either end that round or play another game in the round. If she elects to end the round, then the sum of all scores earned in games played during that round are added to her cumulative score and a new round begins.

Under the assumption that successive game scores are independent and identically distributed random variables whose conditional distribution, given that it is positive, is exponential, we consider this problem under such objectives as minimizing the expected number of rounds until a cumulative score exceeds a given goal g and maximizing the probability that a cumulative score of at least g is obtained by the end of round n. We present the model in the hypothetical context of a clinical trial of a treatment for reducing glycated hemoglobin in diabetic patients.
Biennial hyperepidemic shigellosis in an observant Jewish community
Authors: CALDERON-MARGALIT R. , NAVON-VENEZIA S. , GEFEN D. , AMITAI Z. , BARDA R. , VULIKH I. , SOMPOLINSKY D.
Published: July 2009

We aimed to study patterns of shigellosis in a large observant Jewish community in Israel and to describe local interventions during outbreaks. Surveillance data from the Ministry of Health were used to calculate incidence rates in 1998–2006, both in the city of Bene Beraq and the Tel Aviv district. Information on isolates was collected from the bacteriological laboratory of a community hospital. Public notices and educational conferences conveyed a message to increase personal hygiene and keep ill children at home. During a 9-year period, a clear biennial pattern of outbreaks was noticed. Annual incidence rates ranged between 18 and 353/100 000 population. Shigellosis outbreaks tended to occur in the winter and were attributed to clonally relatedShigella sonneistrains. Outbreaks in Bene Beraq preceded those in the other cities of Tel Aviv district, suggesting propagation of disease. In this population with highly endemic as well as superimposed outbreaks of shigellosis, short-term interventions had no lasting effect on prevention; future studies should focus on community-based programmes to avoid anticipated outbreaks.
Precipitation simulation for Dronning Maud Land using the COSMO Model
Authors: Wacker Ulrike , Ries Hinnerk , Schättler Ulrich
Published: July 2009

A weather episode, characterized by the passage of synoptic disturbances, is investigated for Dronning Maud Land, Antarctica. Due to the sparsity of observations, information about the spatial and temporal distribution of precipitation at high resolution can be gained only by modelling. The simulations presented here are performed with the high-resolution, non-hydrostatic weather forecast COSMO Model with a horizontal mesh size of 7 km. The comparison with observations at four stations shows that the simulation captures the general meteorological conditions well, while a warm bias and a weak daily cycle are found in near-surface temperatures. With regard to precipitation, the timing relates well to the observations; the amount of precipitation, however, is that of an extreme event and possibly overestimated in some regions. The horizontal distribution of precipitation is dominated by topographic effects. The simulations show the general decrease of precipitation toward the interior, as seen in the accumulation climatology, however, the decrease is not monotonous. For example, in the simulations horizontal structures such as precipitation bands of some 100 km width appear on the plateau, which can only be resolved by models with mesh sizes of 10 km or less.
Dimensions of child maltreatment and their relationship to adolescent adjustment
Authors: Wolfe David A. , McGee Robin
Published: July 2009

Research in the broad area of child maltreatment has investigated the effects of these phenomena globally and without much attempt to distinguish the nature and extent of such experiences. This study sought to examine the underlying structure of child maltreatment and relate this structure to current adolescent adjustment. A principal components analysis was conducted with 162 adolescents who had backgrounds of child maltreatment, using a comprehensive measure of such experiences at two developmental time periods (birth to 6 years, and 7–12 years). This analysis resulted in interpretable factors that were used to create scales measuring maltreatment in a continuous, nonredundant manner. These scales were used to test main and interaction effects of each type of maltreatment on current adjustment of adolescent males and females. For males (N = 71), the relationship between early maltreatment and adjustment was significantly enhanced when interactions between physical and psychological abuse and between partner abuse and neglect were entered into the equation. For females (N = 91), current adjustment was significantly related to the developmental period in which neglect or psychological abuse had occurred. Results are discussed in relation to measurement and theoretical issues.
Promoting a Global Culture of Science
Authors: Parekh Bhikhu
Published: July 2009

Basic scientific research is largely limited to the West. Original scientific contributions by the rest of the world are extremely limited, though China, South Korea and India are beginning to make their presence felt. This absence of scientific research is largely due to the undeveloped state of scientific culture. To counter this, systematic and rigorous theoretical training of talented minds is crucial. That requires close interaction with the West. The author suggests various ways to do so.
NATO and Science
Authors: Fenstad Jens Erik
Published: July 2009

To almost everyone the label ‘NATO and Science’ must mean science in the service of weapons and war. And it is true that NATO members do cooperate on a wide range of defence-related aspects of science and technology. But ‘NATO and Science’ also means something very different. Unknown to many, NATO has a third dimension in addition to the military and political ones, and that is the NATO Science Programme. I represented Norway on the NATO Science Committee from 1992 to 2004. Here, I give an account of the programme, how it came about, how it has been implemented, how it changed after the end of the Cold War, and how it is still changing post 9/11. The NATO Science Programme operates in a very specific political context, and I shall try to highlight some aspects of the complex interplay between science and politics in my account.
Planung und Selbstwirksamkeit von Teilnehmern an einer Online-Intervention für entwöhnungsmotivierte Raucher
Authors: Satow Lars , Lippke Sonia , Schwarzer Ralf
Published: July 2009

Zusammenfassung. Ein psychologisches Online-Raucherentwöhnungsprogramm wurde daraufhin untersucht, welche Bedeutung Selbstwirksamkeitserwartung, Handlungsplanung und Initiative für spätere Abstinenz haben. Die Studie enthält sechs Messzeitpunkte und endet mit der Angabe, ob die Teilnehmer es geschafft haben, vier Wochen lang nicht zu rauchen. Diejenigen der insgesamt N = 1 131 Teilnehmer, die bereits ein Planungsverhalten gezeigt haben (zum 1. Messzeitpunkt), wurden eher initiativ, d.h. sie berichteten darüber, einen Tag lang nicht geraucht zu haben (2. Messzeitpunkt). Hoch selbstwirksame Teilnehmer waren den weniger selbstwirksamen zwar nicht in der Initiative überlegen, aber sie erzielten später mehr Abstinenz. In einem Mediatormodell wurde abgebildet, wie Initiative zwischen Planungsverhalten und Abstinenz vermittelt.
Wirkung von Beratung durch die Schulsozialarbeit und sozialer Unterstützung auf die Depressivität und den Selbstwert bei Schülerinnen und Schülern
Authors: Galliker Schrott Bettina , Egger Sawako , Müller Caroline , Fabian Carlo , Drilling Matthias
Published: July 2009

Zusammenfassung. Im Jugendalter wird der Alltag oft von kritischen Lebensereignissen begleitet. Sie können das psychische Wohlbefinden beeinträchtigen. Soziale Unterstützung kann dazu beitragen, das psychische Wohlbefinden zu steigern. In der vorliegenden Studie wird die Wirkung von Schulsozialarbeit-Einzelberatungen – als zusätzliche Unterstützung neben der Unterstützung durch Lehrpersonen, Familie und Klassenkameraden – auf Depressivität und Selbstwert bei Schüler/innen untersucht. Es wurden 436 Schüler/innen im Alter von 11 bis 17 Jahren zweimal schriftlich zu Depressivität, Selbstwert, sozialer Unterstützung, kritischen Lebensereignissen und der Inanspruchnahme sowie dem subjektiven Nutzen der Einzelberatungen befragt. Die Ergebnisse zeigen, dass die Einzelberatungen keinen Einfluss auf die Depressivität und den Selbstwert ausüben können, hingegen gibt es Hinweise dafür, dass der Selbstwert gestärkt wird, sofern die Beratung positiv eingeschätzt wird.
Mean surface topography of the northwest Atlantic: Comparison of estimates based on satellite, terrestrial gravity, and oceanographic observations
Authors: Thompson K. R. , Huang J. , Véronneau M. , Wright D. G. , Lu Y.
Published: July 2009

The accuracy of a new mean sea surface topography (MSST) of the northwest Atlantic is assessed. The MSST is estimated from 12 years of altimeter observations referenced with respect to a new regional geoid based on a blend of Gravity Recovery and Climate Experiment (GRACE), terrestrial, and altimeter‐derived gravity data. The new MSST is first compared to a recently published mean surface topography calculated using an eddy‐permitting model of the North Atlantic. Geostropic currents calculated from the GRACE‐based MSST are next compared to mean surface currents in the northwest Atlantic estimated from the motion of near‐surface drifters corrected for surface Ekman effects. Finally, the mean path of the Gulf Stream is compared to the line of zero skewness of sea level variability which provides a measure of the mean path of unstable, intense ocean currents. Overall the agreement amongst the various estimates of surface topography and circulation is excellent. There are, however, some significant differences that can be separately attributed to problems with the MSST and, in some cases, with the ocean model (in particular the ocean climatology to which it was nudged).
Mapping upper mantle flow beneath French Polynesia from broadband ocean bottom seismic observations
Authors: Barruol G. , Suetsugu D. , Shiobara H. , Sugioka H. , Tanaka S. , Bokelmann G. H. R. , Fontaine F. R. , Reymond D.
Published: July 2009

Upper mantle structures and flow related to the South Pacific Superswell and to the associated short‐lived hotspots are investigated using seismic stations deployed in French Polynesia. Beside island stations, broadband ocean bottom seismometers (BBOBS) have been deployed between the various Polynesian archipelagos to investigate the oceanic upper mantle “unperturbed” by thickened crust or hotspot activity. We investigate seismic anisotropy measured at BBOBS stations and found it rather similar to that from island stations. This confirms the ability of OBS to be used for anisotropy purposes and suggests some homogeneity in the upper mantle pervasive deformation. The two OBS installed on the head of the Society hotspot provide different anisotropy signatures than most of the other French Polynesian stations: one is “isotropic” to SKS waves and the other provides a fast split direction normal to the average value observed in this area, suggesting a more complex mantle flow induced by the plume upwelling.
Cassini detection of Enceladus' cold water‐group plume ionosphere
Authors: Tokar R. L. , Johnson R. E. , Thomsen M. F. , Wilson R. J. , Young D. T. , Crary F. J. , Coates A. J. , Jones G. H. , Paty C. S.
Published: July 2009

This study reports direct detection by the Cassini plasma spectrometer of freshly‐produced water‐group ions (O+, OH+, H2O+, H3O+) and heavier water dimer ions (HxO2)+ very close to Enceladus where the plasma begins to emerge from the plume. The data were obtained during two close (52 and 25 km) flybys of Enceladus in 2008 and are similar to ion data in cometary comas. The ions are observed in detectors looking in the Cassini ram direction exhibiting energies consistent with the Cassini speed, indicative of a nearly stagnant plasma flow in the plume. North of Enceladus the plasma slowing commences about 4 to 6 Enceladus radii away, while south of Enceladus signatures of the plasma interaction with the plume are detected 22 Enceladus radii away.
Control of the energetic proton flux in the inner radiation belt by artificial means
Authors: Shao X. , Papadopoulos K. , Sharma A. S.
Published: July 2009

Earth's inner radiation belt located inside L = 2 is dominated by a relatively stable flux of trapped protons with energy from a few to over 100 MeV. Radiation effects in spacecraft electronics caused by the inner radiation belt protons are the major cause of performance anomalies and lifetime of Low Earth Orbit satellites. For electronic components with large feature size, of the order of a micron, anomalies occur mainly when crossing the South Atlantic Anomaly. However, current and future commercial electronic systems are incorporating components with submicron size features. Such systems cannot function in the presence of the trapped 30–100 MeV protons, as hardening against such high‐energy protons is essentially impractical. The paper discusses the basic physics of the interaction of high‐energy protons with low‐frequency Shear Alfven Wave (SAW) under conditions prevailing in the radiation belts. Such waves are observed mainly in the outer belt, and it is believed that they are excited by an Alfven Ion Cyclotron instability driven by anisotropic equatorially trapped energetic protons. The paper derives the bounce and drift‐averaged diffusion coefficients and uses them to determine the proton lifetime as a function of the spectrum and amplitude of the volume‐averaged SAW resonant with the trapped energetic protons. The theory is applied to the outer and inner radiation belts. It is found that the resonant interaction of observed SAW with nT amplitude in the outer belt results in low flux of trapped protons by restricting their lifetime to periods shorter than days. A similar analysis for the inner radiation belt indicates that broadband SAW in the 1–10 Hz frequency range and average amplitude of 25 pT would reduce the trapped energetic proton flux by more than an order of magnitude within 2 to 3 years. In the absence of naturally occurring SAW waves, such reduction can be achieved by injecting such waves from ground‐based transmitters. The analysis indicates that such reduction requires injection of less than 10 kW of SAW power. Increasing the power will result in the further decrease of the trapped flux. The paper concludes with a brief discussion of techniques that can inject such waves using ground‐based transmitters.
Postdating of flow in Athabasca Valles by faulting of the Cerberus Fossae, Elysium Planitia, Mars
Authors: Vetterlein Joyce , Roberts Gerald P.
Published: July 2009

Mars Orbiter Laser Altimeter (MOLA) topographic data, High Resolution Imaging Science Experiment (HiRISE), Thermal Emission Imaging System (THEMIS), and Mars Orbiter Camera (MOC) images have been used to study the timing of the formation of Athabasca Valles relative to faulting of the southern Cerberus Fossae (SCF). The topography of Athabasca Valles, derived from MOLA elevation data, appears as two troughs on the north and south footwalls of SCF. The same troughs can be identified on the floor of the fossae, indicating that Athabasca Valles predates the accumulation of ∼500 m of vertical fault offset. The topographic expression of Athabasca Valles is preserved on the graben floor because infill by sediment and lava, since formation of the valles and fossae, amounts to less than a few tens of meters. We use this information to discuss the mode of formation of Athabasca Valles and Cerberus Fossae.
Effects of changing glacial coverage on the physical and biogeochemical properties of coastal streams in southeastern Alaska
Authors: Hood Eran , Berner Logan
Published: July 2009

Runoff from mountain glaciers and icecaps is a critical control on physical and chemical conditions of aquatic ecosystems in glaciated watersheds. To date, there has been little research on the biogeochemistry of proglacial streams. Here we use a space for time substitution to evaluate how stream water physical conditions and concentrations of carbon, nitrogen, and phosphorus may be altered by diminishing glacial coverage. For a full annual hydrograph, we sampled six watersheds in southeastern Alaska that ranged in glacier coverage from 0 to 55%. We found that during the summer runoff season (May–October), stream water temperature and specific conductivity were negatively correlated with the percentage of the watershed covered by glacial ice, while stream water turbidity showed a significant positive correlation. Stream water concentrations of dissolved organic carbon (DOC) were typically low (0.5–3.0 mg C L−1) and showed a significant trend toward higher concentrations as watershed glacier coverage decreased. Concentrations of dissolved organic nitrogen (DON) and dissolved inorganic nitrogen also increased significantly with decreasing glacial coverage. In contrast, concentrations of soluble reactive phosphorus decreased with lower glacial coverage. Interestingly, we found that the DOC:DON ratio of stream water dissolved organic matter (DOM) decreased with increasing glacier coverage, suggesting that glaciers may be a source of N‐rich DOM. During winter low flows (November–April) there were few differences in stream water physical and biogeochemical conditions across the six watersheds as glacial inputs diminished and streamflow was dominated by groundwater. Our findings suggest that in southeastern Alaska ongoing glacial recession and the associated land cover change will impact physical and biogeochemical conditions in coastal streams, with implications for salmon spawning habitat, aquatic ecosystem productivity, and fluxes of reactive nutrients to downstream nearshore marine ecosystems.
Tracheoesophageal Voice Restoration After Salvage Total Laryngectomy
Authors: Graville Donna J. , Palmer Andrew D. , Wax Mark K. , Andersen Peter E.
Published: July 2009

Since the 1990s there has been a dramatic shift in the management of advanced laryngeal cancer. Today chemoradiation is often performed as a primary treatment with “salvage” total laryngectomy being performed subsequently if needed. In this article, the authors review the current protocols for the diagnosis of recurrent cancer, the surgical and reconstructive techniques used, and the strategies for management of post-operative complications. There is a paucity of literature about the functional outcomes after this type of procedure. It is known that voice restoration with a tracheoesophageal puncture may be challenging in this population of patients due to the complications associated with their previous treatment. Nonetheless, with appropriate patient selection, careful problem-solving, and persistence, positive outcomes may be achieved.
Linearized model Fokker–Planck collision operators for gyrokinetic simulations. II. Numerical implementation and tests
Authors: Barnes M. , Abel I. G. , Dorland W. , Ernst D. R. , Hammett G. W. , Ricci P. , Rogers B. N. , Schekochihin A. A. , Tatsuno T.
Published: July 2009

A set of key properties for an ideal dissipation scheme in gyrokinetic simulations is proposed, and implementation of a model collision operator satisfying these properties is described. This operator is based on the exact linearized test-particle collision operator, with approximations to the field-particle terms that preserve conservation laws and an H-theorem. It includes energy diffusion, pitch-angle scattering, and finite Larmor radius effects corresponding to classical (real-space) diffusion. The numerical implementation in the continuum gyrokinetic code GS2 [Kotschenreuther et al., Comput. Phys. Comm. 88, 128 (1995)] is fully implicit and guarantees exact satisfaction of conservation properties. Numerical results are presented showing that the correct physics is captured over the entire range of collisionalities, from the collisionless to the strongly collisional regimes, without recourse to artificial dissipation.
Synchronizing Hindmarsh–Rose neurons over Newman–Watts networks
Authors: Jalili Mahdi
Published: July 2009

In this paper, the synchronization behavior of the Hindmarsh–Rose neuron model over Newman–Watts networks is investigated. The uniform synchronizing coupling strength is determined through both numerically solving the network’s differential equations and the master-stability-function method. As the average degree is increased, the gap between the global synchronizing coupling strength, i.e., the one obtained through the numerical analysis, and the strength necessary for the local stability of the synchronization manifold, i.e., the one obtained through the master-stability-function approach, increases. We also find that this gap is independent of network size, at least in a class of networks considered in this work. Limiting the analysis to the master-stability-function formalism for large networks, we find that in those networks with size much larger than the average degree, the synchronizing coupling strength has a power-law relation with the shortcut probability of the Newman–Watts network. The synchronization behavior of the network of nonidentical Hindmarsh–Rose neurons is investigated by numerically solving the equations and tracking the average synchronization error. The synchronization of identical Hindmarsh–Rose neurons coupled over clustered Newman–Watts networks, networks with dense intercluster connections but sparsely in intracluster linkage, is also addressed. It is found that the synchronizing coupling strength is influenced mainly by the probability of intercluster connections with a power-law relation. We also investigate the complementary role of chemical coupling in providing complete synchronization through electrical connections.
Highly conductive modulation doped composition graded p-AlGaN/(AlN)/GaN multiheterostructures grown by metalorganic vapor phase epitaxy
Authors: Hertkorn J. , Thapa S. B. , Wunderer T. , Scholz F. , Wu Z. H. , Wei Q. Y. , Ponce F. A. , Moram M. A. , Humphreys C. J. , Vierheilig C. , Schwarz U. T.
Published: July 2009

In this study, we present theoretical and experimental results regarding highly conductive modulation doped composition graded p-AlGaN/(AlN)/GaN multiheterostructures. Based on simulation results, several multiheterostructures were grown by metalorganic vapor phase epitaxy. Using high resolution x-ray diffraction and x-ray reflectometry, the abruptness of the AlGaN/AlN/GaN interfaces could be determined. Using electron holography, the energetic profile of the valence band could be measured, yielding important information about the vertical carrier transport in such multiheterostructures. The electrical properties of the samples were investigated by measuring the lateral (σL) and vertical (σV) conductivity, respectively. The free hole concentration of a sample optimized in terms of lateral conductivity was measured to be 1.2×1019 cm−3 (295 K) with a mobility of 7 cm2/V s, yielding a record σL of 13.7 (Ω cm)−1. Low temperature Hall measurements (77 K) proved the existence of a two-dimensional hole gas at the AlN/GaN interface, as the lateral conductivity could be increased to 30 (Ω cm)−1 and no carrier freeze out was observable. By substituting the p-GaN layer in a light emitting diode (LED) with an AlGaN/GaN multiheterostructure, the overall voltage drop could be reduced by more than 100 mV (j=65 A/cm2). Furthermore improved current spreading on the p-side of LEDs with integrated AlGaN/AlN/GaN multiheterostructures could be proved by μ-electroluminescence, respectively.
Enhanced efficiency of laser shock cleaning process by geometrical confinement of laser-induced plasma
Authors: Jang Deoksuk , Oh Joon Ho , Lee Jong-Myoung , Kim Dongsik
Published: July 2009

Surface cleaning based on the laser-induced breakdown of gas and subsequent plasma and shock wave generation can remove small particles from solid surfaces. Accordingly, several studies were performed to expand the cleaning capability of the process. In this work, the cleaning process using laser-induced plasma (LIP) under geometrical confinement is analyzed both theoretically and experimentally. Two-dimensional numerical analysis is conducted to examine the behavior of the LIP shock wave under geometrical confinement for several geometries. As a result of the analysis, we propose a simple and practical method to amplify the intensity of laser-induced shock. In the proposed method, a flat quartz plate placed close to the focal point of the laser pulse confines the expansion of the LIP, allowing the plasma to expand only in one direction. As a consequence of the plasma confinement, the intensity of the shock wave produced is increased significantly. Experiments demonstrate that the enhanced shock wave can remove smaller particles from the surface better than the existing process.
Destruction of graphene by metal adatoms
Authors: Boukhvalov D. W. , Katsnelson M. I.
Published: July 2009

The formation energies for mono- and bivacancies in graphene in the presence of adatoms of various metals and small metallic clusters have been calculated. It is shown that transition metal impurities such as iron, nickel, and, especially, cobalt reduce dramatically the vacancy formation energies whereas gold impurities have almost no effect on characteristics of the vacancies. These results highlight that special measures are required in order to protect graphene from damage by transition metal leads.
Reciprocating flow-based centrifugal microfluidics mixer
Authors: Noroozi Zahra , Kido Horacio , Micic Miodrag , Pan Hansheng , Bartolome Christian , Princevac Marko , Zoval Jim , Madou Marc
Published: July 2009

Proper mixing of reagents is of paramount importance for an efficient chemical reaction. While on a large scale there are many good solutions for quantitative mixing of reagents, as of today, efficient and inexpensive fluid mixing in the nanoliter and microliter volume range is still a challenge. Complete, i.e., quantitative mixing is of special importance in any small-scale analytical application because the scarcity of analytes and the low volume of the reagents demand efficient utilization of all available reaction components. In this paper we demonstrate the design and fabrication of a novel centrifugal force-based unit for fast mixing of fluids in the nanoliter to microliter volume range. The device consists of a number of chambers (including two loading chambers, one pressure chamber, and one mixing chamber) that are connected through a network of microchannels, and is made by bonding a slab of polydimethylsiloxane (PDMS) to a glass slide. The PDMS slab was cast using a SU-8 master mold fabricated by a two-level photolithography process. This microfluidic mixer exploits centrifugal force and pneumatic pressure to reciprocate the flow of fluid samples in order to minimize the amount of sample and the time of mixing. The process of mixing was monitored by utilizing the planar laser induced fluorescence (PLIF) technique. A time series of high resolution images of the mixing chamber were analyzed for the spatial distribution of light intensities as the two fluids (suspension of red fluorescent particles and water) mixed. Histograms of the fluorescent emissions within the mixing chamber during different stages of the mixing process were created to quantify the level of mixing of the mixing fluids. The results suggest that quantitative mixing was achieved in less than 3 min. This device can be employed as a stand alone mixing unit or may be integrated into a disk-based microfluidic system where, in addition to mixing, several other sample preparation steps may be included.
Beam emission spectroscopy for density turbulence measurements on the MAST spherical tokamak
Authors: Field A. R. , Dunai D. , Conway N. J. , Zoletnik S. , Sárközi J.
Published: July 2009

Beam emission spectroscopy (BES) of the energetic deuterium (D0) heating beams can provide a means of characterizing the density turbulence in tokamak plasmas. First such measurements have been performed on the MAST spherical tokamak using a trial BES system, which shares the collection optics of the charge-exchange recombination spectroscopy system. This system, with eight spatial channels covering the outer part of the plasma cross section, uses avalanche photodiode detectors with custom preamplifiers to provide measurements at 1 MHz bandwidth with a spatial resolution of 4 cm. Simulations of the measurement, including the beam absorption and excitation, line-of-sight integration of the emission spectrum, and the characteristics of the detection system have been benchmarked against the measured absolute intensity of the Doppler shifted Dα fluorescence from the 50 keV beam. This gives confidence in predictions of the performance of a two-dimensional imaging BES system planned for MAST. Correlation techniques have also provided information on the characteristics of the density turbulence at the periphery of L-mode plasmas as well as density perturbations due to coherent magnetohydrodynamic activity at the edge of H-mode plasmas. Precursor oscillations of the density in the pedestal region to edge-localized modes occurring during H-mode plasmas with a single-null diverted magnetic configuration are also observable in the raw signals from the trial BES system.
One-dimensional slow invariant manifolds for spatially homogenous reactive systems
Authors: Al-Khateeb Ashraf N. , Powers Joseph M. , Paolucci Samuel , Sommese Andrew J. , Diller Jeffrey A. , Hauenstein Jonathan D. , Mengers Joshua D.
Published: July 2009

A reactive system’s slow dynamic behavior is approximated well by evolution on manifolds of dimension lower than that of the full composition space. This work addresses the construction of one-dimensional slow invariant manifolds for dynamical systems arising from modeling unsteady spatially homogeneous closed reactive systems. Additionally, the relation between the systems’ slow dynamics, described by the constructed manifolds, and thermodynamics is clarified. It is shown that other than identifying the equilibrium state, traditional equilibrium thermodynamic potentials provide no guidance in constructing the systems’ actual slow invariant manifolds. The construction technique is based on analyzing the composition space of the reactive system. The system’s finite and infinite equilibria are calculated using a homotopy continuation method. The slow invariant manifolds are constructed by calculating attractive heteroclinic orbits which connect appropriate equilibria to the unique stable physical equilibrium point. Application of the method to several realistic reactive systems, including a detailed hydrogen-air kinetics model, reveals that constructing the actual slow invariant manifolds can be computationally efficient and algorithmically easy.
Carrier transport mechanisms in nonvolatile memory devices fabricated utilizing multiwalled carbon nanotubes embedded in a poly-4-vinyl-phenol layer
Authors: Kim Won Tae , Jung Jae Hun , Kim Tae Whan
Published: July 2009

Transmission electron microscopy images showed that multiwalled carbon nanotubes (MWCNTs) were dispersed in a poly-4-vinyl-phenol (PVP) layer. Capacitance-voltage (C-V) measurements on the Al/MWCNTs embedded in a PVP layer/p-Si (100) devices at 300 K showed a clockwise hysteresis with a large flatband voltage shift due to the existence of the MWCNTs. The magnitude of the flatband voltage shift in the C-V curve for the devices increased with increasing MWCNT concentration. The carrier transport mechanisms for the writing and the erasing processes for the Al/MWCNTs embedded in PVP/p-Si devices are described on the basis of the C-V results.
Comment on “Interaction of small perturbations with shock waves” [Phys. Fluids 16, 4489 (2004)]
Authors: Tumin Anatoli
Published: July 2009

It is pointed out that linearized Rankine–Hugoniot conditions in the noninertial reference frame attached to the instantaneous location of the shock front have the same form as the shock conditions derived in an inertial frame moving at the velocity of the shock at a given time instance.
Response to “Comment on ‘Interaction of small perturbations with shock waves’ ” [Phys. Fluids 21, 079101 (2009)]
Authors: Lubchich Andris A.
Published: July 2009

Tumin’s conclusion refers to the boundary conditions taken in the form Q2−Q1=0. For the solution of our problems the boundary conditions in the form Q2=Q1=C should be used, where constant C may be different on the perturbed and nonperturbed shock surfaces. The difference in C values proceeds from the potential of applied force, resulting in the nonstationary (accelerated) motion of a shock surface. In the noninertial reference frame associated with the perturbed shock surface, the inertia force causes acceleration. The physical reason for its appearance is the force of internal friction inside the viscous front of a shock wave.
Photoconductivity of iron doped amorphous carbon films on n-type silicon substrates
Authors: Wan Caihua , Zhang Xiaozhong , Zhang Xin , Gao Xili , Tan Xinyu
Published: July 2009

The Fe doped a-C films on n-type silicon substrates were deposited by pulse laser deposition. The Fe doped a-C films are p-type semiconductor and they are rich in sp2 (∼75%). I-V characteristics and photoconductivity of the structures were measured in the current in-plane geometry. The photoconductivity with magnitude of 170∼220 was observed under white light illumination with power of 20 mW/cm2 at room temperature. The photoconductivity is ascribed to the p-n junction formed between the p-type a-C: Fe film and the n-type Si substrate whose reverse-biased saturation current increases intensively under illumination.
Magnetic and luminescent properties of multifunctional GdF3:Eu3+ nanoparticles
Authors: Wong Hon-Tung , Chan H. L. W. , Hao J. H.
Published: July 2009

Multifunctional GdF3:Eu3+ nanoparticles were synthesized using a hydrothermal method. Photoluminescent excitation and emission spectra, and lifetime were measured. The average lifetime of the nanoparticles is about 11 ms. The nanoparticle exhibits paramagnetism at both 293 and 77 K, ascribing to noninteracting localized nature of the magnetic moment in the compound. The magnetic properties of GdF3:Eu3+ is intrinsic to the Gd3+ ions, which is unaffected by the doping concentration of the Eu3+ luminescent centers. A measured magnetization of approximately 2 emu/g is close to reported values of other nanoparticles for bioseparation.
Electronic properties of zigzag graphene nanoribbons on Si(001)
Authors: Zhang Zhuhua , Guo Wanlin
Published: July 2009

We show by first-principles calculations that the electronic properties of zigzag graphene nanoribbons (Z-GNRs) adsorbed on Si(001) substrate strongly depend on ribbon width and adsorption orientation. Only narrow Z-GNRs with even rows of zigzag chains across their width adsorbed perpendicularly to the Si dimer rows possess an energy gap, while wider Z-GNRs are metallic due to width-dependent interface hybridization. The Z-GNRs can be metastably adsorbed parallel to the Si dimer rows, but show uniform metallic nature independent of ribbon width due to adsorption-induced dangling-bond states on the Si surface.
Resonance control of membrane reflectors with effective index engineering
Authors: Yang Hongjun , Chuwongin Santhad , Qiang Zexuan , Chen Li , Pang Huiqing , Ma Zhenqiang , Zhou Weidong
Published: July 2009

We report here broadband membrane reflectors based on Fano resonances in patterned silicon nanomembranes. Resonance control of the reflectors was realized either by partially removing buried oxide layer underneath the device layer or by controlled SiO2 film deposition on top of the devices. Both blueshifts and redshifts were demonstrated with a turning range of 50 nm for a center wavelength of 1550 nm. These results demonstrate practical postprocess means for Fano resonance engineering for both narrowband filters and ultracompact broadband reflectors.
MIWI-independent small RNAs (MSY-RNAs) bind to the RNA-binding protein, MSY2, in male germ cells
Authors: Xu Mingang , Medvedev Sergey , Yang Juxiang , Hecht Norman B.
Published: July 2009

The germ cell-specific DNA/RNA-binding protein MSY2 binds small RNAs (MSY-RNAs) that are ≈25–31 nt in length, often initiate with a 5′ adenine, and are expressed in both germ cells and somatic cells. MSY-RNA levels do not decrease in
Miwi
or
Msy2
null mice. Most MSY-RNAs map within annotated genes, but some are PIWI-interacting RNA (piRNA)-like and map to piRNA clusters. MSY-RNAs are in both nuclei and cytoplasm. In nuclei, MSY-RNAs are enriched in chromatin, and in the cytoplasm they are detected in both ribonucleoproteins and polysomes.
Planning a Teaching Episode
Authors: Prasad Vibhore
Published: July 2009

The ability to teach as a doctor in general practice (GP) is not only a requirement for the GP curriculum but is increasingly being recognized as a key skill for any doctor in the modern National Health Service (NHS). The recent guidance document from the General Medical Council, ‘Duties of a doctor’ clearly states: ‘Teaching, training, appraising and assessing doctors and students are important for the care of patients now and in the future. You should be willing to contribute to these activities’. Long gone are the days when doctors were expected to know all they needed to know simply because they were doctors. New models of working and the drive for all new alternative providers of medical services practices to offer training mean that the ability to teach is also an attractive skill for you to offer to future employers. The types of people involved in teaching and learning in primary care are now more diverse than ever before. Working in a multidisciplinary team with other colleagues brings unique challenges that could see you feeling out of your comfort zone. This article will help you to feel more prepared to teach others, using the example of teaching about asthma.
The impact of high-order interactions on the rate of synchronous discharge and information transmission in somatosensory cortex
Authors: Montani Fernando , Ince Robin A. A. , Senatore Riccardo , Arabzadeh Ehsan , Diamond Mathew E. , Panzeri Stefano
Published: July 2009

Understanding the operations of neural networks in the brain requires an understanding of whether interactions among neurons can be described by a pairwise interaction model, or whether a higher order interaction model is needed. In this article we consider the rate of synchronous discharge of a local population of neurons, a macroscopic index of the activation of the neural network that can be measured experimentally. We analyse a model based on physics’ maximum entropy principle that evaluates whether the probability of synchronous discharge can be described by interactions up to any given order. When compared with real neural population activity obtained from the rat somatosensory cortex, the model shows that interactions of at least order three or four are necessary to explain the data. We use Shannon information to compute the impact of high-order correlations on the amount of somatosensory information transmitted by the rate of synchronous discharge, and we find that correlations of higher order progressively decrease the information available through the neural population. These results are compatible with the hypothesis that high-order interactions play a role in shaping the dynamics of neural networks, and that they should be taken into account when computing the representational capacity of neural populations.
Experimental results on synchronization times and stable states in locally coupled light-controlled oscillators
Authors: Rubido Nicolas , Cabeza Cecilia , Martí Arturo C. , Ramírez Ávila Gonzalo Marcelo
Published: July 2009

Recently, a new kind of optically coupled oscillators that behave as relaxation oscillators has been studied experimentally in the case of local coupling. Even though numerical results exist, there are no references about experimental studies concerning the synchronization times with local coupling. In this paper, we study both experimentally and numerically a system of coupled oscillators in different configurations, including local coupling. Synchronization times are quantified as a function of the initial conditions and the coupling strength. For each configuration, the number of stable states is determined varying the different parameters that characterize each oscillator. Experimental results are compared with numerical simulations.