bluuebunny/crossref_metadata_2025 huggingface dataset:
The Political Economy of Religion and Social Insurance in the United States, 1910–1939
Authors: Scheve Kenneth , Stasavage David
Published: December 2006

There are few scholars who would disagree with the proposition that individual economic position and economic risk play a critical role in shaping preferences for income redistribution and social insurance. There is less consensus, however, about the extent to which non-economic factors also influence individual preferences regarding social insurance provision. A number of scholars have examined how issues of race and identity have influenced the development of social insurance programs in the United States, as well as individual attitudes with respect to these programs. In a theoretical context, other authors have considered how attitudes toward income redistribution might also depend upon psychological dispositions such as the “belief in a just world.” In this article, we focus on religiosity as an important factor that can shape both individual preferences and policy outcomes regarding social insurance in the United States. To do so, we develop an argument about religion and social insurance as substitutes that draws both on existing work on the political economy of social insurance and on findings in social psychology regarding what we call the “coping effect” of religion. We test our hypothesis using historical evidence from two early social insurance policies: workers’ compensation legislation enacted by state governments between 1910 and 1930 and New Deal unemployment relief.
Current prevalence of hepatitis delta virus (HDV) infection and the range of HDV genotypes in Lebanon
Authors: RAMIA S. , EL-ZAATARI M. , SHARARA A. I. , RAMLAWI F. , FARHAT B.
Published: December 2006

Recently the prevalence of hepatitis B virus (HBV) genotypes and the association between these genotypes and the clinical status of HBV-infected patients were recently investigated in the Lebanese population. The aim of the additional study reported here was to determine the current prevalence of hepatitis delta virus (HDV) infection and the range of HDV genotypes in this Lebanese population. Two hundred and fifty-eight HBsAg-positive patients (107 asymptomatic blood donors, 92 with chronic hepatitis, 24 with cirrhosis, 15 with hepatocellular carcinoma, 20 patients on haemodialysis) from ten medical centers in Lebanon were tested for antibody to hepatitis D virus (anti-HDV). Those testing positive were analysed further for HDV-RNA and for genotyping by reverse transcriptase–polymerase chain reaction (RT–PCR) and restriction fragment length polymorphism (RFLP). Three samples (1·2%) were anti-HDV positive and out of these, only one was HDV-RNA positive (0·6%) and was analysed as HDV genotype I. Our results point to a low endemicity of HDV in the Lebanese population which is in sharp contrast to data reported from Lebanon 20 years ago and to the situation in neighbouring Arab and non-Arab countries in the Mediterranean region. HDV genotype I seems to be the predominant genotype in Lebanon and the Middle East.
An extended comparative study of language support for generic programming
Authors: GARCIA RONALD , JARVI JAAKKO , LUMSDAINE ANDREW , SIEK JEREMY , WILLCOCK JEREMIAH
Published: December 2006

Many modern programming languages support basic generics, sufficient to implement type-safe polymorphic containers. Some languages have moved beyond this basic support, and in doing so have enabled a broader, more powerful form of generic programming. This paper reports on a comprehensive comparison of facilities for generic programming in eight programming languages: C++, Standard ML, Objective Caml, Haskell, Eiffel, Java, C# (with its proposed generics extension), and Cecil. By implementing a substantial example in each of these languages, we illustrate how the basic roles of generic programming can be represented in each language. We also identify eight language properties that support this broader view of generic programming: support for multi-type concepts, multiple constraints on type parameters, convenient associated type access, constraints on associated types, retroactive modeling, type aliases, separate compilation of algorithms and data structures, and implicit argument type deduction for generic algorithms. We find that these features are necessary to avoid awkward designs, poor maintainability, and painfully verbose code. As languages increasingly support generics, it is important that language designers understand the features necessary to enable the effective use of generics and that their absence can cause difficulties for programmers.
Neuropsychologische Befunde bei Narkolepsie unter besonderer Berücksichtigung von Aufmerksamkeitsfunktionen
Authors: Rieger Martina
Published: December 2006

Zusammenfassung: Aufmerksamkeits- und Gedächtnisprobleme sind wahrscheinlich für eine Vielzahl von Alltagsproblemen bei Narkolepsie-Patienten verantwortlich. Nichtsdestotrotz gibt es nur wenige neuropsychologische Studien bei dieser Patientengruppe. Für die unterschiedlichen Funktionen der Aufmerksamkeit sind aus neuropsychologischer Sicht mehrere funktionell voneinander getrennte Netzwerke verantwortlich (z. B. Orientierung, Alertness/Vigilanz, exekutive Aspekte). Vigilanzdefizite wurden bei Narkolepsie-Patienten vielfach berichtet. Darüber scheint bei Narkolepsie-Patienten auch eine Beeinträchtigung des Netzwerkes für exekutive Aufmerksamkeit vorzuliegen. Befunde bezüglich der Gedächtnisleistungen von Narkolepsie-Patienten sind widersprüchlich. Die Leistungsfähigkeit in anderen Bereichen ist bisher kaum untersucht worden, scheint bei Narkolepsie-Patienten jedoch nicht beeinträchtigt zu sein. Das neuropsychologische Wissen über Narkolepsie ist zurzeit noch relativ begrenzt. Es stellt jedoch eine Basis für erste theoretische Überlegungen, weitere Forschung und die Anwendung in der praktischen Arbeit dar.
Übungseffekte in den TAP Untertests Test Go/Nogo und Geteilte Aufmerksamkeit sowie dem Aufmerksamkeits-Belastungstest (d2)
Authors: Bühner Markus , Ziegler Matthias , Bohnes Björn , Lauterbach Kristine
Published: December 2006

Zusammenfassung: Das Ziel der vorliegenden Untersuchung bestand darin, zu prüfen, ob Probanden durch Übung Leistungsverbesserungen in zwei Untertests aus der Testbatterie zur Aufmerksamkeitsprüfung, TAP, (Geteilte Aufmerksamkeit, Go/Nogo) und dem Aufmerksamkeits- und Belastungstest d2 erzielen bzw. Transfereffekte auf den d2 durch die Übung der TAP-Untertests auftreten. Das Untersuchungsdesign bestand aus fünf Gruppen, von denen jede zunächst den Test d2 einmal bearbeitete. Danach wurde in einer Gruppe ein Leistungsmotivationsinventar durchgeführt und in den anderen vier Gruppen viermal in kurzem Abstand hintereinander entweder eine der Bedingungen des TAP-Untertests Geteilte Aufmerksamkeit (Bedingung “Töne”, “Quadrate”, “Quadrate und Töne”) oder der TAP-Untertest “Go/Nogo”. Insgesamt nahmen 125 Studierende an der Untersuchung teil. Für die untersuchten TAP-Untertests ergaben sich testspezifische Übungseffekte. Im Test d2 zeigte sich für den Konzentrationsleistungswert ein starker Übungsgewinn, es ergaben sich jedoch keine Transfereffekte der TAP-Tests auf den Test d2.
Zur Reaktivität von Kausaldiagramm-Analysen beim komplexen Problemlösen
Authors: Blech Christine , Funke Joachim
Published: December 2006

Zusammenfassung. Die Produktion von Kausaldiagrammen gilt als eine Methode zur Wissensdiagnostik beim Bearbeiten komplexer Probleme. Ein Experiment sollte untersuchen, inwieweit Kausaldiagramm-Analysen den Umgang mit dynamischen Systemen beeinflussen. Es wurde vermutet, dass prozessbegleitende Kausaldiagramm-Analysen einen hypothesentestenden Problemlösestil sensu Klahr und Dunbar (1988) unterstützen und intensivieren. Als beobachtbare Konsequenz wurden ein erhöhter Erwerb von Strukturwissen und gesteigerte Leistungen im Steuern des Systems erwartet. 64 studentische Versuchspersonen bearbeiteten das Szenario “Ökosystem“ über fünf Durchgänge. Personen, die nach jedem Durchgang ein Kausaldiagramm anfertigten, zeigten sich im abschließend erworbenen Strukturwissen Vergleichspersonen überlegen, die einen oberflächlichen Rekognitionstest, eine nicht szenariobezogene Aufgabe oder gar keine zusätzliche Aufgabe absolviert hatten. Dies spricht für einen Reaktivitätseffekt. Allerdings benötigten kausal-instruierte Personen weder mehr Zeit noch explorierten sie das System geschickter. Auch im Steuern des Systems profitierten sie nicht von ihrem Wissensvorteil, sondern erbrachten Leistungen auf dem Niveau der Kontrollprobanden. Die abschließende Diskussion sieht in der Reaktivität des Instruments einen diagnostischen Gewinn.
Die Bedingungen des Flow-Erlebens in einer experimentellen Spielsituation
Authors: Schiefele Ulrich , Roussakis Emmanouil
Published: December 2006

Zusammenfassung. Die vorliegende Studie stellt die Replikation eines Experiments von Rheinberg und Vollmeyer (2003) dar. Diese Autoren konnten zeigen, dass das Erleben von Flow beim Ausführen eines Computerspiels theoriegemäß von dem Ausmaß der Passung zwischen Anforderung und Fähigkeit abhängt. In unserer Studie spielten 76 Studierende das Computerspiel “Roboguard“ auf einer Spielstufe mit optimaler Passung zwischen Anforderung und Fähigkeit und zwei Spielstufen mit geringer Passung (sehr leicht, sehr schwer). Gegenüber der Studie von Rheinberg und Vollmeyer wurde das Computerspiel so modifiziert, dass die zu leichte und zu schwere Spielstufe weniger extrem waren. Für die schwere Spielstufe bedeutete dies, dass man als Spieler zumindest minimale Erfolge erzielen konnte, und nicht - wie bei Rheinberg und Vollmeyer - nahezu handlungsunfähig war. Die Ergebnisse zeigten die erwarteten Effekte für die leichte und optimale Spielstufe, nicht aber für die zu schwere Spielstufe. Wider Erwarten gaben die Pbn auch auf der schweren Spielstufe an, ein hohes Ausmaß an Flow zu erleben. Als Erklärung wird angeführt, dass Überforderung in Spielsituationen unter bestimmten Umständen das Flow-Erleben nicht reduziert. Spiele, wie das verwendete Roboguard, sind daher nicht generell, sondern nur bei spezifischen Fragestellungen geeignet, um Flow-Forschung zu betreiben.
Phänomenologie schulischer Langeweile
Authors: Götz Thomas , Frenzel Anne C.
Published: December 2006

Zusammenfassung. Ziel der vorliegenden Studie war eine Identifizierung und Kategorisierung phänomenologischer Aspekte schulischer Langeweile. Hierzu wurden Daten von 50 Gymnasiasten der 9. Jahrgangsstufe (50% weiblich) erhoben. Die auf der Basis von Schüleraussagen generierten Kategorien zur Phänomenologie schulischer Langeweile erwiesen sich als sehr inhaltsheterogen und deuteten auf verschiedene Formen des Langeweileerlebens hin. Es wurden vier Formen schulischer Langeweile identifiziert und bezüglich der Dimensionen Aktivation und Valenz in einem heuristischen Modell verortet. Theoretische und praktische Implikationen werden diskutiert.
Vergleich diagnostischer Entscheidungen von Novizen und Experten am Beispiel der Schullaufbahnempfehlung
Authors: van Ophuysen Stefanie
Published: December 2006

Zusammenfassung. Wie unterscheiden sich die Entscheidungen von Diagnostikern unterschiedlicher Expertise im pädagogischen Kontext? Am Beispiel der Schullaufbahnempfehlung wurden die Differenziertheit der Bewertung diagnostischer Kriterien und die Wahrscheinlichkeit von systematischer Urteilsverzerrung bei Grundschullehrkräften (Experten) und Lehramtstudierenden (Novizen) verglichen. Dazu füllten 140 Versuchspersonen einen Fragebogen aus, in dem sie eine Reihe von Schülermerkmalen hinsichtlich ihrer Wichtigkeit für die Übergangsempfehlung bewerteten. Sodann gaben sie ihre Empfehlung für die angemessene weiterführende Schulform ab. Erwartungsgemäß beurteilten die Lehrkräfte die Wichtigkeit verschiedener Inhaltsbereiche differenzierter als die Studierenden. Studierende ließen sich in ihrem Urteil stärker von einem vorläufigen, selbstgefällten Urteil leiten und wechselten ihre Entscheidung trotz nachfolgender widersprüchlicher Informationen seltener als die Lehrkräfte. Diese Bestätigungstendenz ließ sich auf die Abwertung solcher Informationen zurückführen, die mit der ersten Entscheidung inkonsistent waren.
Hausaufgabenverhalten aus der Perspektive der Selbstregulation
Authors: Perels Franziska , Löb Martin , Schmitz Bernhard , Haberstroh Julia
Published: December 2006

Zusammenfassung. Zielsetzung dieses Beitrags ist die Untersuchung des Hausaufgabenverhaltens von Schülern der 8. Klasse des Gymnasiums aus der Perspektive der Selbstregulation. Mit Hilfe von über sieben Wochen täglich erhobenen Prozessdaten wurde das außerschulische Lernverhalten untersucht und die Angemessenheit des zu Grunde gelegten Prozessmodells der Selbstregulation ( Schmitz, 2001 ; Schmitz & Wiese, 2006 ) überprüft. Die Ergebnisse geben Hinweise auf die Angemessenheit des Prozessmodells der Selbstregulation für den außerschulischen Kontext. Weiterhin konnte die Prozesserhebung präzise Informationen zu spezifischen Aspekten des Selbstregulationsansatzes hinsichtlich des außerschulischen Lernverhaltens liefern. Hierbei wird insbesondere auf die Emotionen beim Lernen sowie auf verschiedene Aspekte der Lernzeit (durchschnittliche Lernzeit, Verlauf der Vorbereitung auf eine Klassenarbeit, Zusammenhang zwischen Hausaufgabenbeginn und Effektivität des Lernens) eingegangen.
Skalierung von “Theory of Mind“-Aufgaben
Authors: Kristen Susanne , Thoermer Claudia , Hofer Tanja , Aschersleben Gisa , Sodian Beate
Published: December 2006

Zusammenfassung. Die von Wellman und Liu (2004) für den englischsprachigen Raum entwickelte “Theory of Mind“-Skala wurde in einer Übersetzung ( Hofer & Aschersleben, 2004 ) an einer Stichprobe von 107 3- bis 5-jährigen Kindern validiert. Sowohl die Annahme einer einheitlichen konzeptuellen Progression als auch die Skalenpassung konnten repliziert werden. Abweichend von Wellman und Liu (2004) fand sich ein Effekt der Aufgabenfolge mit einer besseren Skalenpassung und insgesamt besserer Performanz bei nach Schwierigkeit ansteigender Präsentation. Insgesamt sprechen die Befunde dafür, dass die deutsche Version der “Theory of Mind“-Skala die Entwicklung der begrifflichen Erschließung des mentalen Bereichs im Vorschulalter adäquat abbildet und eine zuverlässige Methode darstellt, den individuellen Stand der “Theory of Mind“-Entwicklung zu messen.
Evaluation in der Kunsttherapie: Die Objektivierung des Subjektiven?
Authors: Limberg Renate
Published: December 2006

Zusammenfassung. Eine an der naturwissenschaftlichen quantitativen Forschung orientierte Evaluation reduziert die Wirkungskontrolle auf die Erfassung einzelner, abgrenzbarer Parameter und schließt komplexe Fragestellungen aus. Dieses Forschungsdesign ist auf die künstlerischen Therapien nicht übertragbar. Das ästhetische Paradigma erweitert dagegen den rationalen Forschungszugang um die Dimension der sinnlichen Erfahrung. Dabei steht die Wirkung der therapeutischen Maßnahmen auf den Einzelnen und seinen individuellen Entwicklungsprozess im Vordergrund. Dieser Prozess kann nur aus der subjektiven Wahrnehmung des Einzelnen beurteilt und bewertet werden. An einem Beispiel wird ein Weg der Effektivitätskontrolle, der einem erweiterten Wissenschaftsverständnis entspricht, vorgestellt.
Development of tracer relations and chemical ozone loss during the setup phase of the polar vortex
Authors: Tilmes Simone , Müller Rolf , Grooß Jens‐Uwe , Nakajima Hideaki , Sasano Yasuhiro
Published: December 2006

The development of tracer‐tracer relations in the polar stratosphere is analyzed during the period when the vortex forms and a westerly circulation develops after polar summer (the setup phase of the polar vortex). We consider high southern latitudes from March to June for winter 1997 and 2003 and high northern latitudes from September to October 2003. ILAS and ILAS‐II satellite observations and model simulations are used to investigate chemical changes in O3, NO2 and HNO3 during these periods. Tracer‐tracer relations and meteorological analyses consistently indicate a separation of the incipient polar vortex into two parts. The area within the edge of the inner vortex is isolated from the outer part that is still influenced by mixing with air of midlatitude origin. In the Antarctic in April, ozone concentrations vary by about 0.5 ppmv within the isolated inner vortex between 500 and 600 K potential temperature. This inhomogeneous distribution of ozone is likewise obvious in MIPAS satellite measurements. Box model simulations explain that the low ozone concentrations in April are caused by chemical ozone loss due to catalytic cycles which are mainly driven by NOx at this time of the year. The simulations also explain the observed conversion of NOx to HNO3 during the setup phase of the 2003 Antarctic vortex. During June in the Antarctic, the internal vortex transport barrier disappears and ozone mixing ratios become homogeneous throughout the entire vortex. At that time, no further ozone loss occurs because of the lack of sunlight.
A global analysis of wave potential energy in the lower stratosphere derived from 5 years of GPS radio occultation data with CHAMP
Authors: de la Torre A. , Schmidt T. , Wickert J.
Published: December 2006

This paper presents the first results of the global long‐term potential energy and mean potential energy per unit mass associated to wave activity (WA) in the lower and middle stratosphere, obtained from Global Positioning System radio occultation (GPS‐RO) temperature profiles, retrieved during the last 5 years from the CHAMP (CHAllenging Minisatellite Payload) satellite. We excluded temperature variations corresponding to the wavelike character of the Quasi Biennial oscillation (QBO). Possible limitations and distortions expected from our analysis are pointed out. Systematic annual and interannual features, clearly evidenced through 5 years of observations as a function of height, latitude and time are shown. We confirm some previously reported characteristics, in particular interannual requiring a sufficiently long period of observation, in addition to others not reported yet. In particular, a general stronger (weaker) wave activity is observed associated to apparent vertical wavelengths longer (shorter) than 4 km. The tropical/extratropical signatures decrease/increase with increasing altitude. At equatorial latitudes, WA interannual enhancements, related to QBO, are observed just below zonal wind zero contours corresponding to westerly shears. A significant decrease of WA is seen where the zonal wind is minimum. Both at equatorial and middle latitudes, an increased WA appears close above the TP, following its annual height oscillation and above 30 km height. At higher latitudes, a systematic annual variation of WA is observed, exhibiting stronger enhancements in winter SH respect to NH, but in SH, taking place during late winter and early spring. This enhanced WA, associated during 2002 to the stratospheric warming observed in that year, appears here as a systematic annual stratospheric feature. Its intensity increases with altitude, from 25 to 35 km. Inertio‐gravity waves generated by geostrophic adjustment during the maximum of the southern polar vortex (polar night jet) between late August and mid‐ September, could constitute a main source of this WA enhancement.
Assessing tropical cyclone trends in the context of potential sampling biases
Authors: Fasullo J.
Published: December 2006

Recently observed trends in the tropical cyclone record are assessed in the context of potential sampling biases. Multi‐member syntheses of the hurricane record are created and subjected to time‐varying sampling rates and intensity‐specific biases to assess the biases' ability to induce spurious trends. While simple linear trends in sampling frequency can be imposed that account for the observed trends in major storms, the same biases result in trends in weaker storms that are significantly at odds with observations. Moreover, it is found that intensity specific biases, which must invariably contribute to prolonged storm durations for weaker categories, are inconsistent with observations. It is concluded therefore that the proposed sampling deficiencies are unable to account fully for recently reported trends, either individually or when considered in tandem. The finding of positive trends must therefore either be robust or result from complex, and as of yet unexplained, sampling biases.
Inferring the eddy‐induced diffusivity for heat in the surface mixed layer using satellite data
Authors: Zhai Xiaoming , Greatbatch Richard J.
Published: December 2006

The eddy‐induced diffusivity for heat at the surface of the western North Atlantic Ocean is estimated using satellite altimetry and sea surface temperature data. A rotational eddy flux is removed from the total eddy flux following the ideas of Marshall and Shutts (1981). The resulting eddy‐induced diffusivity shows considerable spatial variability with a value near 104 m2 s−1 just to the south of the Gulf Stream and values in the range 1–2 × 103 m2 s−1 within the Gulf Stream itself.
Icelandic rhythmics: Annual modulation of land elevation and plate spreading by snow load
Authors: Grapenthin Ronni , Sigmundsson Freysteinn , Geirsson Halldór , Árnadóttir Thóra , Pinel Virginie
Published: December 2006

We find strong correlation between seasonal variation in CGPS time series and predicted response to annual snow load in Iceland. The load is modeled using Green's functions for an elastic halfspace and a simple sinusoidal load history on Iceland's four largest ice caps. We derive E = 40 ± 15 GPa as a minimum value for the effective Young's modulus in Iceland, increasing with distance from the Eastern Volcanic Zone. We calculate the elastic response over all of Iceland to maximum snow load at the ice caps using E = 40 GPa. Predicted annual vertical displacements are largest under the Vatnajökull ice cap with a peak‐to‐peak seasonal displacement of ∼37 mm. CGPS stations closest to the ice cap experience a peak‐to‐peak seasonal displacement of ∼16 mm, consistent with our model. East and north of Vatnajökull we find the maximum of annual horizontal displacements of ∼6 mm resulting in apparent modulation of plate spreading rates in this area.
Direct observation of the F region dynamo currents and the spatial structure of the EEJ by CHAMP
Authors: Lühr Hermann , Maus Stefan
Published: December 2006

The satellite CHAMP in its low‐altitude polar orbit, and with its high‐resolution magnetic field measurements, provides the opportunity to investigate ionospheric currents in great detail. In this study we focus on average features of equatorial current systems during day time. Considering quiet time observations from the period Aug. 2000 to Oct. 2004 we determined the mean spatial structure of the EEJ current. The existence of reverse currents at the flanks of the primary eastward current is confirmed. More importantly, average characteristics of the F region dynamo driven currents are observed for the first time throughout the daytime. The meridional current system, driven by westward thermospheric winds, peaks around noon. Similar meridional currents, but flowing in the opposite sense, are observed at the dusk sector. At CHAMP altitudes we find over the dip equator in the F region a vertical sheet current of about 6 mA/m oriented downward at noon and an upward current of 4 mA/m around sunset.
Ionospheric disturbances during the magnetic storm of 15 July 2000: Role of the fountain effect and plasma bubbles for the formation of large equatorial plasma density depletions
Authors: Kil Hyosub , Paxton Larry J.
Published: December 2006

We investigate the role of the fountain effect and plasma bubbles for the formation of the large equatorial plasma depletions during the geomagnetic storm of 15 July 2000. The large equatorial plasma depletions are detected in the Atlantic sector on the night of the 15th by the Defense Meteorological Satellite Program (DMSP) F15 and the first Republic of China Satellite (ROCSAT‐1). The observations show discontinuous drop of the plasma density at the walls of the depletions, flat plasma density inside the depletions, and persistence or growth of the depletions over night. These properties are not consistent with the trough morphology induced by the fountain effect. The coincident ionospheric observations of DMSP F15 and ROCSAT‐1 demonstrate that the large depletions are created in the longitude regions where plasma bubbles are present. The occurrence of the large depletions after sunset, elongation in the north‐south direction, formation of steep walls, and colocation with plasma bubbles at lower altitudes or earlier times suggest that the large depletions are closely associated with plasma bubbles.
Meteor trail diffusion and fields: 2. Analytical theory
Authors: Dimant Y. S. , Oppenheim M. M.
Published: December 2006

A meteoroid penetrating the Earth's atmosphere leaves behind a trail of dense plasma embedded in the lower E/upper D region ionosphere. While radar measurements of meteor trail evolution have been collected and used to infer meteor and atmospheric properties since the 1950s, no accurate quantitative model of trail fields and diffusion exists. This paper describes a two‐dimensional (2‐D) analytical theory of meteor trail plasma physics that fills the gap between the studies of dense trail physics without background plasma, 1‐D models, and those for small disturbances. Major new results include an estimate of the spatial distribution of a trail's ambipolar electric potential and a quantitative model of diffusion rates, both parallel and perpendicular to the geomagnetic field, with a prediction that in the course of their diffusion, dense trails transform from anisotropic to more isotropic. These results are important for interpreting specular and nonspecular radar measurements of meteor trails and for accurate modeling of plasma instabilities. A companion paper shows that the results from this analytical theory agree well with simulations results.
Comparing MODIS and AERONET aerosol optical depth at varying separation distances to assess ground‐based validation strategies for spaceborne lidar
Authors: Kovacs Thomas
Published: December 2006

The difficulties in validating aerosol optical depth from spaceborne lidars such as the Geoscience Laser Altimeter System (GLAS) on board IceSat and the lidar on board the Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite with ground‐based instruments are discussed. Because observations are often not collocated, matching errors, which increase with separation distance, confound the validation of instrumental errors. These matching errors can be assessed by comparing the aerosol total‐column optical depth measured in a swath by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on board the Terra satellite with point Aerosol Robotic Network (AERONET) Sun photometer measurements at different separation distances. In particular, the relationship of the correlation of the two sensors' aerosol total‐column optical depth observations with increasing spatial separation is determined. The use of back trajectories to reduce the loss in correlation with increasing spatial separation is then evaluated. Matching errors are found to increase faster over land than over water sites, with the correlation dropping by 20% in 200 km over the land sites and 500 km over the ocean sites. Constraining the area over which the MODIS aerosol optical depth is calculated to within 30° azimuth of the average back trajectory only improved the correlation for a site where long‐range transport of aerosols often occurs.
The Citizen Petition: For the Public Good or Brands Behaving Badly?
Authors: Glass Gregory , Collins Erin
Published: December 2006

Over the past several years, there has been a perception in the generic industry that brand companies have been using the Citizen Petition process with the US Food and Drug Administration in order to extend the lifecycles of their brand products and prevent or delay approvals of generic applications. While these filings lend credence to this perception, it nonetheless leaves open questions regarding purpose and effect. This paper examines Petition filings since 2004 and explores their purported purpose, their likely purpose, and impact on generic market dynamics.
What is the Value of Authorised Generic Agreements? Assessments on the French Market
Authors: Peny Jean-Michel , Covilard Jean-Pierre
Published: December 2006

The worldwide generic market should keep on growing at the expense of brand-name companies and reach sales of US$97bn, in 2010. To resist this increasing competitive pressure and to maintain a slice of the market, brand-name companies may negotiate with generic companies to postpone the launch of their competitive products or they may license their own generic products to competitor generic companies. In the USA, these so-called ‘authorised generics’ have generated substantial profits for brand-name companies and to their generic partners, provided however that they are launched before patent expiry during an exclusivity period. In Europe, there are no legal exclusivity periods granted to generic companies that can challenge original brands, and the strategic and financial values relative to this strategy are not well established. This paper proposes a specific approach to assess the benefits of authorised generic deals for both the brand-name companies and their generic partners. The application of this approach on several authorised generic deals carried out in France shows that the duration of the exclusivity period, the number of generic partners involved, and their relative competitive position are the most important success factors. In addition, it appears that brand-name companies could have a financial interest to propose, for their ‘easy-to-substitute’ original brands, authorised generic licenses to all generic companies. In such a situation, generic partners will benefit from a guaranteed market access and a product identical to the original brand while avoiding risks of patent infringement.
Hudson’s theorem for finite-dimensional quantum systems
Authors: Gross D.
Published: December 2006

We show that, on a Hilbert space of odd dimension, the only pure states to possess a non-negative Wigner function are stabilizer states. The Clifford group is identified as the set of unitary operations which preserve positivity. The result can be seen as a discrete version of Hudson’s theorem. Hudson established that for continuous variable systems, the Wigner function of a pure state has no negative values if and only if the state is Gaussian. Turning to mixed states, it might be surmised that only convex combinations of stabilizer states give rise to non-negative Wigner distributions. We refute this conjecture by means of a counterexample. Further, we give an axiomatic characterization which completely fixes the definition of the Wigner function and compare two approaches to stabilizer states for Hilbert spaces of prime-power dimensions. In the course of the discussion, we derive explicit formulas for the number of stabilizer codes defined on such systems.
Metal organic vapor phase epitaxy of BiSbTe3 films on (001) GaAs vicinal substrates
Authors: Kim Jeong-Hun , Jeong Dae-Yong , Kim Jin-Sang , Ju Byeong-Kwon
Published: December 2006

We have investigated the growth of BiSbTe3 films by metal organic vapor phase epitaxy on (001) GaAs vicinal substrates. A detailed experimental study of the surface morphologies of BiSbTe3 films grown on GaAs (001) vicinal surfaces was carried out and is discussed in this paper with a view to understanding the step-step interaction kinetics that result in step bunching. BiSbTe3 layers grown on nominal (001) GaAs substrates exhibit triangular facet structures consisting of atomically flat plateau areas separated by steps. In contrast, the growth of films on vicinal substrates was found to result in regular arrays of terrace step structures. The formation of step bunches and rectangular terraces on such film surface is attributed to the preferential incorporation of adatoms at step or kink sites and lateral growth rate anisotropy.
Beam of metastable krypton atoms extracted from a microwave-driven discharge
Authors: Ding Y. , Bailey K. , Davis A. M. , Hu S.-M. , Lu Z.-T. , O’Connor T. P.
Published: December 2006

A microwave-driven discharge is used to produce a thermal beam of metastable krypton atoms at the 5s[3∕2]2 level with an angular flux density of 7×1014s−1sr−1, while consuming 1×1017kryptonatoms∕s. This source of atomic beam uses commercially available microwave parts, and has achieved comparable beam flux and excitation efficiency with a previously described source that employs a rf-driven discharge [C. Y. Chen et al., Rev. Sci. Instrum. 72, 271 (2001)].
Ferroelectric crossovers triggered by isovalent A-site substitution in Pb0.7La0.2TiO3
Authors: Soon Hwee Ping , Wang John
Published: December 2006

A -site isovalent substitutions trigger ferroelectric transitions in Pb0.7(1−x)A0.7xLa0.2TiO3, where A=Ca, Sr, or Ba. The transitions are dependent on the type and amount of substitutions such as Ca2+, Sr2+, and Ba2+. A transition from normal ferroelectric (FE) to relaxor FE (RFE) is induced by Ca2+, Ba2+, and Sr2+ substitutions at x=0.30, 0.40, and 0.60, respectively. Interestingly, a further crossover to quantum paraelectriclike behavior occurred in Pb0.7(1−x)Ca0.7xLa0.2TiO3 with x=0.60, in addition to the transition from FE to RFE. The observed ferroelectric crossovers and temperature dependence of relative permittivity ε′(T) can be correlated to the structural parameters and breakdown in long-range polar order brought by the A-site isovalent substitution.
Imprint mechanism in integrated Bi-rich SrBi2Ta2O9 capacitors: Influence of the temperature-dependent polarization
Authors: Goux L. , Wouters D. J.
Published: December 2006

In this work, we characterize the imprint properties of three-dimensional Sr0.8Bi2.2Ta2O9 (SBT) ferroelectric capacitors integrated in 0.18μm technology using metal-organic chemical vapor deposition of SBT. We investigated the dependence of hysteresis loops on the storage temperature and duration after poling the capacitors. Also, the influence of unipolar and bipolar voltage cyclings, respectively, during and after the imprint stress was studied. We show that the imprint-induced shift of the hysteresis is limited for all the investigated stress conditions, and we associate this low shift mainly to a pronounced polarization decrease with the temperature, deviating from the Landau-Devonshire law. Our results also suggest that emission within the SBT layer is dominant over injection from the electrode in the imprint mechanism at 0V bias. On the other hand, dynamic imprint stress results suggest an increased contribution of carrier injection. Regarding the switchable polarization, it was observed to be higher after an imprint stress due to a wake-up of ferroelectric domains, which may be thermally driven but was evidenced to be prominently field driven. The wake-up and the imprint are discussed in terms of trapping/detrapping mechanisms.
The simulation of the three-dimensional lattice hydrophobic-polar protein folding
Authors: Guo Yu-zhen , Feng En-min
Published: December 2006

One of the most prominent problems in computational biology is to predict the natural conformation of a protein from its amino acid sequence. This paper focuses on the three-dimensional hydrophobic-polar (HP) lattice model of this problem. The modified elastic net (EN) algorithm is applied to solve this nonlinear programming hard problem. The lattice partition strategy and two local search methods (LS1 and LS2) are proposed to improve the performance of the modified EN algorithm. The computation and analysis of 12 HP standard benchmark instances are also involved in this paper. The results indicate that the hybrid of modified EN algorithm, lattice partition strategy, and local search methods has a greater tendency to form a globular state than genetic algorithm does. The results of noncompact model are more natural in comparison with that of compact model.
Time correlation function and finite field approaches to the calculation of the fifth order Raman response in liquid xenon
Authors: DeVane Russell , Space Brian , Jansen Thomas l. C. , Keyes T.
Published: December 2006

The fifth order, two-dimensional Raman response in liquid xenon is calculated via a time correlation function (TCF) theory and the numerically exact finite field method. Both employ classical molecular dynamics simulations. The results are shown to be in excellent agreement, suggesting the efficacy of the TCF approach, in which the response function is written approximately in terms of a single classical multitime TCF.
Excited state properties and quadratic optical nonlinearities in charged organic chromophores: Theoretical analysis
Authors: Inerbaev Talgat M. , Saito Shigeki , Belosludov Rodion V. , Mizuseki Hiroshi , Takahashi Masae , Kawazoe Yoshiyuki
Published: December 2006

As it has been found experimentally [K. Clays and B. Coe, Chem. Mater. 15, 642 (2003); B. J. Coe et al., 126, 10418 (2004)], elongation of the conjugation path length and N-arylation in stilbazolium chromophores both lead to substantial enhancement of the molecular optical nonlinearities. In the present contribution the authors perform a quantum chemical analysis of the excited state properties and quadratic nonlinear optical responses of a series of this type of dyes. Nonlinear optical responses are estimated by both finite-field and two-state model approaches that demonstrate an excellent qualitative mutual agreement. Time-dependent density functional theory calculations on the isolated cations predict redshift in the energy of the intramolecular charge transfer transition that is overestimated for cations with the longer conjugation path length. At the same time, in comparison with the Stark spectroscopy measurements the differences between the excited and ground state dipole moments are grossly underestimated for all compounds. The inclusion of solvent effect by polarizable continuum model affords a better agreement with experiment for these quantities. The authors’ calculations demonstrate the crucial dependence of the electronic excitation properties on the way of the investigated compound geometry optimization. The origin of such dependence is discussed.
Universal approach to accurate resistivity measurement for a single nanowire: Theory and application
Authors: Gu Wenhua , Choi Hyungsoo , Kim Kyekyoon (Kevin)
Published: December 2006

A universal four-contact method is proposed to accurately determine the resistivity of a single nanowire and other nanostructures. Unlike the conventional four-contact method or two-contact method, the present scheme does not require nonrectifying (Ohmic) contacts to the nanowire and can completely eliminate the systematic error resulting from the contact resistance or the resistance difference between the contacts. The present method has been applied to copper nanowire and can be used as a universal resistivity measurement scheme for all nanowires and other nanostructures.
Investigation into the nanoindentation size effect using static atomistic simulations
Authors: Jeng Yeau-Ren , Tan Chung-Ming
Published: December 2006

Strain gradient theory predicts that the increase in hardness of a material is inversely proportional to the square root of the indentation depth for indentation in the micrometer regime. The aim of this study is to investigate the validity of this phenomenon in the nanometer regime. The simulation results indicate that nanohardness does not have a strong depth dependence in the nanometer regime. However, if the Oliver-Pharr scheme is applied for the measurement of the contact area, a prominent size effect is nevertheless observed. Therefore, this study also investigates the inability of the Oliver-Pharr scheme in the nanometer regime.
Intriguing conducting properties of HfOxNy thin films prepared from the Hf[N(C2H5)2]4
Authors: Chou Yi-Hsuan , Chiu Hsin-Tien , Kuo Teng-Fang , Chi Cheng-Chung , Chuang Shiow-Huey
Published: December 2006

Hafnium nitride films were prepared on the Si(100) substrates by the metal-organic chemical vapor deposition method using Hf[N(C2H5)2]4. The prepared samples were then oxidized in air, followed by rapid-thermal annealing to produce HfOxNy thin films, meanwhile the associated physical properties were investigated. The x-ray photoelectron spectroscope analysis unveiled that the composition of the films is HfOxNy. In addition, the films after the rapid-thermal annealing treatments at various temperatures revealed salient features in their physical properties, such as capacitance and conductivity. On this basis, the feasibility of using the HfOxNy layers as high-k dielectrics in complementary metal oxide semiconductor transistors was also discussed.
Resonances of individual metal nanowires in the infrared
Authors: Neubrech F. , Kolb T. , Lovrincic R. , Fahsold G. , Pucci A. , Aizpurua J. , Cornelius T. W. , Toimil-Molares M. E. , Neumann R. , Karim S.
Published: December 2006

With infrared spectroscopic microscopy using synchrotron light, the authors studied resonant light scattering from single metal nanowires with diameters in the 100nm range and with lengths of a few microns. The Au and Cu nanowires were electrochemically grown in polycarbonate etched ion-track membranes and transferred on infrared-transparent substrates. Significant antennalike plasmon resonances were observed in good agreement with exact light-scattering calculations. The resonances depend not only on length and diameter but also on the dielectric surrounding of the nanowire. The observed maximum extinction at resonance corresponds to an electromagnetic far-field enhancement by a factor of about 5.
Amplitude contrast of a single gadolinium atom reconstructed by a wave field restoration method
Authors: Takai Yoshizo , Tsuji Toshiyuki , Chikada Hidekazu , Taya Masaki
Published: December 2006

Single gadolinium atoms in fullerenes encapsulated in a single-wall carbon nanotube were observed by a wave field restoration method based on three-dimensional Fourier filtering in transmission electron microscopy. Single gadolinium atoms were clearly resolved not only in the imaginary part image but also in the real part image of the exit wave field due to an improved signal-to-noise ratio by Fourier filtering and resolution enhancement by correcting spherical aberration and twofold astigmatism. This result indicates that the present method has potential to clarify compositional details of the sample by using their image contrasts.
Observation of the dΠg3←cΣu+3 band system of C2
Authors: Kokkin Damian L. , Reilly Neil J. , Morris Christopher W. , Nakajima Masakazu , Nauta Klaas , Kable Scott H. , Schmidt Timothy W.
Published: December 2006

A new band system of C2, dΠg3←cΣu+3 is observed by laser induced fluorescence spectroscopy, constituting the first direct detection of the cΣu+3 state of C2. Observations were made by laser excitation of cΣu+3(v″=0) C2, produced in an acetylene discharge, to the dΠg3(v′=3) level, followed by detection of Swan band fluorescence. Rotational analysis of this band yielded rotational constants for the cΣu+3(v″=0) state: B0=1.9218(2)cm−1, λ0=−0.335(4)cm−1 and γ0=0.011(2)cm−1. The vibrational band origin was determined to be ν3−0=15861.28cm−1.
Directly deposited nanocrystalline silicon thin-film transistors with ultra high mobilities
Authors: Lee Czang-Ho , Sazonov Andrei , Nathan Arokia , Robertson John
Published: December 2006

The authors report ultrahigh mobility nanocrystalline silicon thin-film transistors directly deposited by radio-frequency plasma enhanced chemical vapor deposition at 150°C. The transistors show maximum effective field effect mobilities of 450cm2∕Vs for electrons and 100cm2∕Vs for holes at room temperature. The authors argue that the key factor in their results is the reduction of the oxygen content, which acts as an accidental donor.
Large photocurrent generation in multiwall carbon nanotubes
Authors: Castrucci P. , Tombolini F. , Scarselli M. , Speiser E. , Del Gobbo S. , Richter W. , De Crescenzi M. , Diociaiuti M. , Gatto E. , Venanzi M.
Published: December 2006

The authors demonstrate the ability of multiwall carbon nanotubes to generate photocurrents in the near ultraviolet and visible spectral ranges using electrochemical photocurrent measurements. The photogenerated current depends on the excitation wavelength similar to that for single wall carbon nanotubes. Its intensity and modulation can be related to the carbon nanotubes morphology. The maximum photon-to-current conversion efficiency is approximately 7%, about 50 times higher than that reported for single wall carbon nanotubes. This result is of particular relevance for photovoltaic nanodevices and solar energy conversion applications.
Depolarizing field and “real” hysteresis loops in nanometer-scale ferroelectric films
Authors: Bratkovsky A. M. , Levanyuk A. P.
Published: December 2006

The authors give detailed analysis of the effect of depolarizing field in nanometer-size ferroelectric capacitors studied by Kim et al. [Phys. Rev. Lett. 95, 237602 (2005)]. They calculate a critical thickness of the homogeneous state and its stability with respect to domain formation for strained thin films of BaTiO3 on SrRuO3∕SrTiO3 substrate within the Landau theory. While the former (2.5nm) is the same as given by ab initio calculations, the actual critical thickness is set by the domains at 0.8nm. There is a large Merz’s activation field for polarization relaxation. Remarkably, the results show a negative slope of the “actual” hysteresis loops, a hallmark of the domain structures in ideal thin films with imperfect screening.
Properties of p-type and n-type ZnO influenced by P concentration
Authors: Hu Guangxia , Gong Hao , Chor E. F. , Wu Ping
Published: December 2006

The electrical conductivity of P-doped ZnO can be controlled by changing the P-doping concentration. With increasing P concentration, ZnO can be changed from n type to p type. At the same time, a redshift of the band gap energy is observed by using the photoluminescence spectroscopy and UV-visible spectrophotometer. X-ray diffraction results show that lattice spacings of ZnO increase with P concentration, which indicates that P substitutes O, and this leads to a lattice spacing increase and an optical band gap energy decrease.
Improved transport properties of the two-dimensional electron gas in AlGaN∕GaN heterostructures by AlN surface passivation layer
Authors: Chen D. J. , Tao Y. Q. , Chen C. , Zhang R. , Zheng Y. D. , Wang M. J. , Shen B. , Li Z. H. , Jiao G. , Chen T. S.
Published: December 2006

The transport properties of the two dimensional electron gas (2DEG) in AlGaN∕GaN heterostructures with AlN, Si3N4, and SiO2 passivation layers and without passivation layer were investigated using Hall effect measurements over a temperature range of 30–550°C. Compared to the Si3N4 and SiO2 passivation dielectrics, the AlN film led to an obvious increase not only in carrier concentration but also in mobility of the 2DEG. The variation of the carrier concentration with temperature in the AlN passivated sample is also smaller in comparison with the Si3N4 passivated sample. These indicate that the AlN film is a promising passivation dielectric. In addition, the results from Hall and high-resolution x-ray diffraction measurements show that the change of strain after passivation contributes only in a relatively small proportion to the variation of the carrier concentration in AlGaN∕GaN heterostructures.
Method for increasing the photoconductive response in conjugated polymer/fullerene composites
Authors: Peet J. , Soci C. , Coffin R. C. , Nguyen T. Q. , Mikhailovsky A. , Moses D. , Bazan G. C.
Published: December 2006

The authors poly(3-hexylthiophene)/[6,6]-phenyl C61-butyric acid methyl ester present a technique for modifying the internal structure of bulk heterojunction films which yields significantly improved photoconductivity. This method comprises the addition of alkyl thiol molecules to the polymer/fullerene solution prior to spin coating. Based on the steady-state and transient photoconductivity measurements, the photoresponsivity is an order of magnitude greater than that in films spun from pristine solvent; additionally, the carrier mobility measurements indicate significant increase in the hole mobility, consistent with the enhanced structural order inferred from x-ray diffraction and optical absorption measurements.