124,801 research outputs found
The Exception That Proves the Rule: How Sodium Chelation Can Alter the Charge-Cell Binding Correlation of Fluorescein-Based Multimodal Imaging Agents
No full textIn the present study we describe and explain an aberrant behavior in terms of receptor binding profile of a fluorescein-based multimodal imaging agent for gastrin releasing peptide receptor (GRPR) visualization by elucidating a chelating mechanism on sodium ions of its fluorescent dye moiety. This hypothesis is supported by both biological results and spectroscopic analyses of different fluorescein-carrying conjugates and an equally charged set of analogous tartrazine-based GRPR-binding imaging agents. Fluorescein interacts with sodium which reduces the overall negative charge of the dye molecule by one. This reduction in apparent total net charge explains the exceptional behavior found for the fluorescein-based multimodal bioconjugate in the context of the charge-cell binding correlation hypothesis
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Linac design for intense hadron beams
No full textEnergy and environment are two major concerns in the 21st century. At present, the energy required for the daily life still mainly relies on the traditional fossil fuel resources, but the caused air pollution problem and greenhouse effect have seriously threatened the sustainable development of mankind. Another adopted energy source which can provide a large fraction of electricity for the world is the nuclear fission reaction. However, the increasing high-radioactive spent nuclear fuels, which half-lives are usually >1 million years, are becoming the hidden perils to the earth. A great advance in accelerator physics and technology opens an opportunity to solve this dilemma between man and nature, because powerful accelerator-based neutron sources can play important roles for clean nuclear power production, for example: - The Accelerator-Driven System (ADS) can serve as an easy control of a sub-critical fission reactor so that the nuclear fuels will be burnt more completely and safely. - The EUROTRANS project launched by EU is investigating another application of the ADS technology to reduce the radiotoxicity and the volume of the existing nuclear waste greatly and quickly in a transmutation way. - The developing international IFMIF plant will be used to test and qualify reactor materials for future fusion power stations, which can produce much cleaner nuclear electricity more efficiently than the fission ones. Therefore, the R&D of high-power driver linacs (HPDL) is of a worldwide importance. As the proverb said, "everything is hard at the beginning", the front end is the most difficult part for realizing an HPDL machine. Based on the RFQ and H-type DTL structures, this dissertation is dedicated to study the beam dynamics in the presence of significantly strong space-charge effects while accelerating intense hardon beams in the low- and medium-beta-region. Besides the 5mA/30mA, 17MeV proton injector (RFQ+DTL) and the 125mA, 40MeV deuteron DTL of the above-mentioned EUROTRANS and IFMIF facilities, a 200mA, 700keV proton RFQ has been also intensively studied for a small-scale but ultra-intense neutron source FRANZ planned at Frankfurt University. The most remarkable properties of the FRANZ RFQ and the IFMIF DTL are the design beam intensities, 200mA and 125mA, which are the record values for the proton and deuteron linacs, respectively. Though the design intensities for the two development stages, XT-ADS (5mA) and EFIT (30mA), of the EUROTRANS injector are well within the capability of the modern RF linac technology, the special design concept for an easy upgrade from XT-ADS to EFIT brings unusual challenges to realize a linac layout which allows flexible operation with different beam intensities. To design the 200mA FRANZ RFQ and the two-intensity EUROTRANS RFQ, the classic LANL (Los Alamos National Laboratory) Four-Section Procedure, which was developed by neglecting the space-charge forces, is not sufficient anymore. Abandoning the unreasonable constant- B (constant-transverse-focusing-strength) law and the resulting inefficient evolution manners of dynamics parameters adopted by the LANL method, a new design approach so-called "BABBLE", which can provide a "Balanced and Accelerated Beam Bunching at Low Energy", has been developed for intense beams. Being consistent with the beam-development process including space-charge effects, the main features of the "BABBLE" strategy (see Pages 55-58) are: 1) At the entrance, the synchronous phase is kept at = phi s = -90° while a gradual increase in the electrode modulation is started so that the input beam can firstly get a symmetrical and soft bunching within a full-360° phase acceptance. 2) In the following main bunching section, B is increasing to balance the stronger and stronger transverse defocusing effects induced by the decreasing bunch size so that the bunching speed can be fast and safely increased. 3) When the real acceleration starts, the quickly increased beam velocity will naturally weaken the transverse defocusing effects, so B is accordingly falling down to avoid longitudinal emittance growths and to allow larger bore apertures. Taking advantage of the gentle initial bunching and the accelerated main bunching under balanced forces enabled by the "BABBLE" strategy, a 2m-long RFQ with beam transmission in excess of 98% and low emittance growths has been designed for FRANZ, and a 4.3m-long RFQ with almost no beam losses and flat emittance evolutions at both 5mA and 30mA has been designed for EUROTRANS. All design results have proven that the "BABBLE" strategy is a general design approach leading to an efficient and robust RFQ with good beam quality in a wide intensity-range from 0mA to 200mA (even higher). To design the IFMIF DTL and the injector DTL part of the EUROTRANS driver linac, which have been foreseen as the first real applications of the novel superconducting CH-DTL structure, intensive attempts have been made to fulfill the design goals under the new conditions, e.g. long drift spaces, SC transverse focusing elements and high accelerating gradients. For the IFMIF DTL, the preliminary IAP design has been considerably improved with respect to the linac layout as well as the beam dynamics. By reserving sufficient drift spaces for the cryosystem, diagnostic devices, tuner and steerer, introducing SC solenoid lenses and adjusting the Linac Design for Intense Hadron Beams accelerating gradients and accordingly other configurations of the cavities (see Pages 78-80), a more realistic, reliable and efficient linac system has been designed. On the other hand, the specifications and positions of the transverse focusing elements (see Pages 81-82) as well as the phase- and energy-differences between the bunch-center particle and the synchronous particle at the beginning of the phi s=0° sections have been totally redesigned (see Pages 83-84) resulting in good beam performances in both radial and longitudinal planes. For the EUROTRANS injector DTL, in addition to the above-mentioned procedures, extra optimization concepts to coordinate the beam dynamics between two intensities, such as employing short adjustable rebunching cavities with phi s = -90° (see Page 116), have been applied. ...Energie und Umwelt sind zwei Hauptthemen im 21. Jahrhundert. Zurzeit wird der für das tägliche Leben benötigte Energiebedarf hauptsächlich aus fossilen Quellen abgedeckt, doch die dadurch verursachte Luftverschmutzung und der Treibhauseffekt bedrohen ernsthaft die Weiterentwicklung der Menschheit. Eine weitere Energiequelle, welche einen Großteil der Elektrizität für den Weltverbrauch liefert, ist die Kernspaltung. Jedoch stellen die ständig anwachsenden Mengen von radioaktivem Müll mit Halbwertszeiten von über eine Million Jahre ein wachsendes Problem dar. Die Beschleunigerphysik und -technologie eröffnet eine Lösungsmöglichkeit dieses Problems, weil beschleunigergestützte intensive Neutronenquellen eine wichtige Rolle für eine saubere nukleare Energieerzeugung übernehmen können: - Beschleunigergetriebene unterkritische Reaktorsysteme (englisch: "Accelerator Driven Systems", ADS) ermöglichen eine leichte Kontrolle des Reaktorbetriebes, so dass die Kernbrennstoffe vollständiger und sicherer verbraucht werden. - Das von der Europäischen Union geförderte Forschungsprogramm für die Transmutation von hoch radioaktiven Abfällen EUROTRANS wendet die ADS-Technologie an mit dem Ziel, die Radiotoxizität und Menge des radioaktiven Abfalls stark zu mindern. - Die "International Fusion Material Irradiation Facility" (IFMIF) wird geeignete Materialien für Fusionsreaktoren wie ITER durch Beschuss mit Neutronen untersuchen und so einen langfristigen Beitrag für eine sauberere und effizientere Erzeugung von Kernenergie durch Fusionsreaktionen leisten. Deshalb ist die Forschung und Entwicklung von Hochleistungs-Treiber-Linearbeschleuniger (Linacs) von weltweiter Bedeutung. Wie das Sprichwort (auch in China) sagt: "Aller Anfang ist schwer", so ist der Nieder- und Mittelenergiebereich gewöhnlich der anspruchsvollste Teil eines Beschleunigers. In der vorliegenden Dissertation wurden Strahldynamikuntersuchungen bei starkem Einfluss der Raumladungseffekte durchgeführt, wobei intensive Hadronenstrahlen im niedrigen und mittleren Energiebereich durch Hochfrequenz-Quadrupol- (englisch: "RFQ") und H-Mode Driftröhrenstrukturen (DTL) beschleunigt werden. Neben dem 5 bzw. 30mA, 17MeV Protoneninjektor (RFQ und DTL) für EUROTRANS und dem 125mA, 40MeV Deuteronen - DTL für IFMIF, wurde auch die strahldynamische Auslegung eines 200mA, 700keV Protonen-RFQs für die intensive Neutronenquelle FRANZ an der Goethe-Universität Frankfurt untersucht. Die markantesten Eigenschaften des FRANZ-RFQs sowie des IFMIF-DTLs sind die Strahlintensitäten von 200mA respektive 125mA, welche jeweils Rekordwerte für Protonen- und Deuteronen- Linacs darstellen. Obgleich die geplanten Intensitäten der beiden Entwicklungsstufen XT-ADS (5mA) und EFIT (30mA) des EUROTRANS-Projektes sich im Rahmen der technologischen Möglichkeiten moderner Beschleuniger befinden, stellte in diesem Fall die Option einer leichten Ausbaumöglichkeit des XT-ADS Entwurfes für EFIT wegen der unterschiedlichen Teilchenströme eine besondere Herausforderung dar. Die am Los Alamos National Laboratory (LANL) unter Vernachlässigung der Raumladungskräfte entwickelte Vier-Sektionen-Prozedur für den RFQ-Entwurf war im Falle des 200mA FRANZ-RFQs sowie des EUROTRANS-RFQs nicht geeignet. Unter Aufgabe des von LANL entwickelten konstantes B-Kriteriums (konstante transversale Fokussierstärke), welches in den vorliegenden Fällen zu ineffizienten Parametersätzen geführt hätte, wurde ein neues Designkonzept für intensive Teilchenstrahlen mit der Bezeichnung "Balanced and Accelerated Beam Bunching at Low Energy" (BABBLE, siehe Seiten 55-58) ausgearbeitet. Dieses ist im Einklang mit dem Prozess der Strahlformierung unter Berücksichtigung der Raumladungseffekte und hat folgende Hauptmerkmale: 1) Die Synchronphase wird am Eingang konstant bei phi s=-90° gehalten, während die Modulation der Elektroden langsam erhöht wird. Dadurch erfährt der Strahl eine symmetrische und gemäßigte Fokussierung innerhalb der gesamten 360° Phasenakzeptanz. 2) In der nachfolgenden Hauptfokussierungs-Sektion wird B erhöht um die immer größer werdende ransversale Defokussierung zu kompensieren, wodurch auch die Geschwindigkeit und Stabilität des Fokussierungsprozesses erhöht wird. 3) Zu Beginn der Hauptbeschleunigung kommt es durch die schnell anwachsende Teilchengeschwindigkeit zu einer natürlichen Reduktion der transversalen Defokussierung, so dass auch B entsprechend reduziert wird, um das longitudinale Emittanzwachstum zu vermeiden und um größere Aperturen zu ermöglichen. Unter Ausnutzung der Vorteile der mäßigen anfänglichen Fokussierung sowie der daran anschließenden schnellen Fokussierung im Kräftegleichgewicht gemäß der "BABBLE"-Strategie, konnten ein 2m langer RFQ für FRANZ mit 98% Transmission und geringem Emittanzwachstum sowie ein 4.3m langer RFQ für EUROTRANS mit sehr geringen Teilchenverlusten und flachem Emittanzverlauf sowohl für 5mA wie auch für 30mA entworfen werden. Diese Ergebnisse bestätigen die "BABBLE"-Strategie als allgemeinen Design-Ansatz, welcher effiziente RFQs mit guter Strahlqualität in einem weiten Bereich der Strahlintensitäten (0mA bis 200mA und höher) ermöglicht. Beim Entwurf des IFMIF DTLs sowie des Injektor DTLs für EUROTRANS, welche als erste Anwendungen der neuartigen, supraleitenden CH-Driftröhrenstruktur dienen könnten, wurden mit großer Sorgfalt versucht, die Designkriterien bei neuen Randbedingungen wie längere Driftstrecken, supraleitende transversale Fokussierelemente und hohe Beschleunigungsgradienten möglichst gut zu erfüllen. Im Falle des IFMIF-DTL wurde das ursprüngliche IAP-Design wesentlich verbessert, sowohl im Hinblick auf den Aufbau des Beschleunigers wie auch strahldynamisch. Es wurden ausreichend Driftstrecken für die Kryoelemente, Diagnosekomponenten, Tuner und Steeringmagnete vorgesehen, ferner wurden supraleitende Solenoidlinsen eingesetzt und die Beschleunigungsgradienten angepasst (siehe Seiten 78-80). Daraus resultierte ein realistischerer, zuverlässiger und effizienter Entwurf. Darüber hinaus wurden die Spezifikationen und Lagen der transversal fokussierenden Elemente (siehe Seiten 81-82), sowie die Phasen- und Energieablagen zwischen Schwerpunkt der Teilchenverteilung und Sollteilchen am Eingang der phi s=0° Sektionen neu bestimmt (siehe Seiten 83-84), wodurch verbesserte Ergebnisse in allen Raumebenen erzielt wurden. Im Falle des EUROTRANS Injektor-DTLs, wurden zusätzlich zu den obengenannten Maßnahmen Konzepte zur Anpassung der Strahldynamik für zwei verschiedene Strahlintensitäten entwickelt, wie zum Beispiel der Einsatz kurzer, abstimmbarer Rebunching- Kavitäten mit phi s = -90° (siehe Seite 116) ..
An Extended RBAC Model for Task Delegation in Workflow Systems
No full textItem does not contain fulltex
Pragmatic Case Studies as a Source of Unity in Applied Psychology
No full textTo unify or not to unify applied psychology: that is the question. In this article we review pendulum swings in the historical efforts to answer this question—from a comprehensive, positivist, “top-down,” deductive yes between the 1930s and the early 60s, to a postmodern no since then. A rationale and proposal for a limited, “bottom-up,” inductive yes in applied psychology is then presented, employing a case-based paradigm that integrates both positivist and postmodern themes and components. This paradigm is labeled “pragmatic psychology” and, its specific use of case studies, the “Pragmatic Case Study Method” (“PCS Method”). We call for the creation of peer-reviewed journal-databases of pragmatic case studies as a foundational source of unifying applied knowledge in our discipline. As one example, the potential of the PCS Method for unifying different angles of theoretical regard is illustrated in an area of applied psychology, psychotherapy, via the case of Mrs. B. The article then turns to the broader historical and epistemological arguments for the unifying nature of the PCS Method in both applied and basic psychology.Peer reviewe
Dr. Edwin Wright Collection: Author Unknown
No full textNotes - The author relates several short stories about his neighbours including Alex McDonell, homesteading and life around Meanook and Athabasca (1 page
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
[18F]-Fluorodeoxyglucose-positron emission tomography in rats with prolonged cocaine self-administration suggests potential brain biomarkers for addictive behavior
No full textThe DSM5-based dimensional diagnostic approach defines substance use disorders on a continuum from recreational drug use to habitual and ultimately addicted behavior. Biomarkers that are indicative of recreational drug use and addicted behavior are lacking. We performed a translational [18F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) study in the multi-dimensional 0/3crit model of cocaine addiction. Addict-like (3crit) and non-addict-like (0crit) rats, which shared identical life conditions and levels of cocaine self-administration, were acquired for FDG-PET under baseline conditions and following cocaine and yohimbine challenges. Compared to cocaine-naïve control rats, 0crit animals showed higher glucose uptake in the caudate putamen (CPu) and medial prefrontal cortex (mPFC) respect to naïve controls. 3crit animals did not show this adaptive higher glucose utilization, but had lower uptake in several cortical areas. Both cocaine and yohimbine challenges affected glucose uptake in control rats in several brain sites, but not in 0crit and 3crit rats, indicating that impaired glucose mobilization in response to these challenges is not specifically associated with addictive behavior. Compared to 0crit, 3crit rats showed higher reinstatement responses, which were negatively associated with glucose uptake in the ventral tegmental area. Data indicate that cocaine non-addict- and addict-like phenotypes are associated with several potential biomarkers. Specifically, we propose that increased glucose uptake in the CPu and mPFC is a function of controlled drug use, whereas a loss of striatal and prefrontal metabolic activity and reduced uptake in cortical areas are indicative of addictive behavior
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
No full textThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
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