bluuebunny/crossref_metadata_2025 huggingface dataset:
Eine Apparatur zur Desorptionsspektroskopie an porösen Festkörpern bei tiefen Temperaturen
Authors: Fietzke F. , Jäckel M.
Published: July 2007

A newly developed apparatus for Temperature Programmed Desorption spectroscopy (TPD) in the temperature range between 10 and 100 K is presented. It is provided for the investigation of porous solids especially for use in vacuum engineering, for instance activated charcoal and zeolithe. Favoured working regime is a linear temperature schedule with some parts of a Kelvin per minute, but all other schedules and a variation of the heating rate over the factor 10 are also available. The whole measuring process takes place automatically and under computer control – so a simultaneous registration of a large number of measured gases is possible.
Plasmaeinsatz für innovative Verbindungstechniken in der Elektronikfertigung
Authors: Liekdke V.
Published: July 2007

Die Behandlung im Niederdruckplasma ersetzt den bisher unvermeidlich scheinenden Flußmitteleinsatz, um elektronische Funktionsbaugruppen nach dem Bestücken mit Bauelementen lötbar zu gestalten. Flußmittelreste können zu Qualitätseinbußen führen und sind unter Umweltaspekten als kritisch zu betrachten. Neuen Bauelementformen, bei denen Flußmittel auch aus Verfahrensgründen problematisch sind, wird hiermit der Weg zur breiten Anwendung geöffnet.
Die metallorganische Molekularstrahlepitaxie für die Erzeugung neuartiger III‐V‐Halbleiterstrukturen
Authors: Heinecke Harald
Published: July 2007

Prinzipiell ist die metallorganische Molekularstrahlepitaxie (MOMBE oder CBE) die konsequenteste Form der Niedrigdruck‐metallorganischen Gasphasenepitaxie (MOVPE). Die Konzeption eines MOMBE‐Systems ist jedoch aufgrund des Molekularstrahlcharakters durch gänzlich andere Kriterien bestimmt als es in einem durch Fluß‐Dynamik bestimmten MOVPE‐System der Fall ist. Die Charakteristika einer MOMBE‐Epitaxie‐Anlage werden diskutiert und die zentralen Einsichten in den Wachstumsmechanismus des sogenannten oberflächenselektiven Wachstums werden angesprochen. Die Erkenntnisse bezüglich des Mechanismus können für die Verwirklichung von neuartigen Bauelementkonzepten ausgenutzt werden, wie z.B. für die laterale Integration von photonischen Bauelementen oder niedrig‐dimensionalen elektronischen Bauelementen. Darüber hinaus beeinflussen diese Erkenntnisse und Möglichkeiten auch wiederum die Entwicklungen von MOMBE‐Anlagen der nächsten Generation.
Explosionsschutzmaßnahmen an Vakuumpumpen
Authors: Ripper Lois J.
Published: July 2007

In zahlreichen industriellen Verfahren müssen Dämpfe brennbarer Lösemittel oder reaktive Gase abgesaugt und verdichtet werden. Hierbei sind Maßnahmen zur Vermeidung von Gefahren erforderlich, die sich durch Bildung reaktionsfähiger Gemische oder Förderung reaktiver Gase ergeben können. Die vorliegende Abhandlung gibt einen umfassenden Überblick über die anwendbaren Explosionsschutzmaßnahmen, die physikalischen Grundlagen zur Beurteilung einer Explosionsgefahr, die in Vakuumpumpen entstehenden Zündquellen sowie die Anforderungen, die sich aus der gegenwärtigen Vorschriftenlage ergeben. Aus zahlreichen Untersuchungen anderer Autoren wurden ferner relevante Stoffdaten entnommen, gegenübergestellt sowie graphisch aufbereitet, so daß dem Leser eine Übersicht über die physikalischen Zusammenhänge, aber auch Hilfe bei der Beurteilung von Explosionsgefahren in den Innenräumen von Maschinen und Apparaten geboten werden.

Der Verfasser kann auf Erfahrungen durch eine jahrzehntelange Beratungstätigkeit als technischer Aufsichtsbeamter der Berufsgenossenschaft der chemischen Industrie, sowie als Obmann mehrerer berufsgenossenschaftlicher und DIN Arbeitskreise und Leiter der „GS‐Prüfstelle für Verdichter”︁ zurückblicken.
Trockenlaufende Drehschieber‐Vakuumpumpen in einer Vielzweck‐Produktionsanlage
Authors: Müller K. P.
Published: July 2007

Die Herstellung von 45 verschiedenen chemischen Produkten in einer Vielzweck‐Produktionsanlage stellt höchste Anforderungen an das Vakuumsystem.

Bei Hoechst AG, Werk Griesheim, ist diese Anlage mit trockenlaufendem Vakuumsystem seit 3 Jahren erfolgreich im Einsatz.
Vakuumdruckmessung und ‐regelung in der chemischen Verfahrenstechnik
Authors: Dohmen H.
Published: July 2007

In der chemischen Verfahrenstechnik gibt es vielseitige Druckmeß‐ und Regelanwendungen im Überdruck‐ und Vakuumbereich. Der nachfolgende Beitrag stellt in einem kurzen Überblick die Besonderheiten bei Vakuumanwendungen als Ergänzung zu den hinreichend bekannten Kriterien der MSR‐Technik vor.
Überlastgrenzen bei Hochvakuumpumpen
Authors: Hablanian M.
Published: July 2007

Hochvakuumpumpen besitzen einen maximalen Einlaßdruck, oberhalb dessen sie nicht mehr ordnungsgemäß funktionieren. Für den Betrieb einer Vakuumanlage ist es wichtig, eine Annäherung an die Überlastgrenzen zu erkennen und entsprechend zu reagieren. Der vorliegende Aufsatz beschäftigt sich mit grundlegenden Überlegungen, ab welchem Druck eine Hochvakuumpumpe eingesetzt wird, wobei die besondere Bedeutung des Gasdurchflusses gegenüber der Bedeutung des Drucks herausgearbeitet wird. Der Umschaltpunkt zwischen Grob‐Pumpe und Hochvakuum‐Pumpe hängt vom Verhältnis der Saugvermögen beider Pumpen ab. Es werden praktische Empfehlungen für die Auslegung und den Betrieb von Anlagen gegeben. Eine Überlastung von Hochvakuum‐Pumpen kann zu Problemen führen (z. B. Rückströmung und Ölverlust) sowohl bei gastransportierenden Pumpen (Diffusions‐ und Turbomolekular‐Pumpen) als auch bei gasbindenden Pumpen (Ionenzerstäüber‐ und Kryo‐Pumpen). Um diese zu vermeiden, sollte der vorübergehende Druckanstieg während des Umschaltens nicht länger als einige Sekunden anhalten.
Properties of Optical Thin Films
Authors: Gunkel Claus
Published: July 2007

Es wird der Versuch einer geschlossenen Darstellung der Dünnen Schichten in der Optik gemacht. Dabei werden neben reflexmindernden auch reflexerhöhende Schichten, sowie Filter‐ und Sonderschichten analytisch oder an Beispielen beschrieben. Das optische Glas, als besonders vielfältiges und nuancenreiches Substrat, wird mit in die Betrachtung einbezogen.
Qualitätssicherung durch Prozeßüberwachung
Authors: Sele G.
Published: July 2007

Quality assurance in low‐pressure semiconductor manufacturing processes is greatly supported by on‐line monitoring of the vacuum conditions and process atmospheres. Modern quadrupole mass analyzers in multiplexing mode meet today's stringent requirements of multichamber tools and help to increase production yields.
Trockenes dreistufiges Vorpumpensystem für die Prozeß‐ und Verfahrenstechnik
Authors: Barfuß H.
Published: July 2007

Im Gegensatz zu den bislang auf dem Markt erhältllichen trockenen Vorvakuumpumpen (Klauen/Wälzkolbenprinzip) wurde ein trockenes System entwikkelt, das wesentliche Vorteile aufweist. Die angewandte Rotorgeometrie mit zwei durch ein Zahnradpaar gegenläufig drehenden Rotoren zeichnet sich dadurch aus, daß einer der beiden Rotoren die reine Förderung des Mediums und der andere auch das Öffnen und Schließen von Ein‐ und Auslaßquerschnitten übernimmt (Steuerkolben). Die Rotorprofile wurden in ihrer Geometrie und Abstufung zueinander optimal abgestimmt.

Nachfolgende Darstellungen zeigen die Pumpphasen vom Ansaugen bis zum Ausstoßen des Mediums für eine der 3 Pumpstufen. Das theoretische Saugvermögen errechnet sich aus (V1 + V2) 2 n, wobei n die Nenndrehzahl der Pumpe ist.
Betriebsmittel für mechanische Vakuumpumpen in der chemischen und der verwandten Industrie
Authors: Oswald Dieter
Published: July 2007

Bei allen Vakuumpumpen, die mit einer Flüssigkeit als Dichtmedium arbeiten, müssen verschiedene pumpenspezifische Eigenarten beachtet werden. Im Artikel werden Flüssigkeitsringvakuumpumpen nur kurz gestreift, da dieser Pumpentyp alternative Betriebsmittel schon länger nutzt. In anderen mechanischen Vakuumpumpen wird diese Möglichkeit, Probleme zu lösen, noch nicht so häufig in Betracht gezogen. In diesem Artikel werden die verschiedenen Ansatzpunkte für den Einsatz von alternativen Betriebsmittel angesprochen, so daß auch bei Drehschieber‐ und anderen mechanischen Vakuumpumpen dieser Lösungsweg zusätzliche Beachtung finden kann.
Saphir‐Entladungsgefäße zur Plasmadiagnostik
Authors: Schöpp Heinz
Published: July 2007

Der Energiebedarf für Beleuchtungszwecke spielt wirtschaftlich eine bedeutende Rolle, die Verringerung der Kosten durch Einsatz effizienter Lichtquellen ist deshalb eine wichtige Aufgabe. Forschungs‐ und Entwicklungsarbeiten auf diesem Gebiet sind auch zukünftig unumgänglich. Durch die Verwendung neuer Werkstoffe und Verfahren entstehen auch neue Lichtquellen. Keramische Werkstoffe haben schon vor einigen Jahren auf dem Gebiet der Hochdruck‐Natriumdampf‐Lampen zu einem Qualitätssprung geführt. Neuere Entwicklungen bei Hochdruck‐ Metallhalogendampf‐Lampen erschließen auch diesem Lichtquellentyp sehr gute Zukunftschancen. Aus Kostengründen werden derartige Lichtquellen in gesinterten Entladungsgefäßen gefertigt. Diese Gefäße lassen jedoch wegen des durchscheinenden Materials keine räumlich aufgelösten Untersuchungen zu. Für Grundlagenuntersuchungen sind durchsichtige Entladungsgefäße notwendig. Es wird eine Lösung vorgestellt, die durch gezielte technische Veränderungen den Einsatz von durchsichtigem, monokristallinem Saphir ermöglicht. Die vorliegende Beschreibung soll zeigen, daß durch Auswahl von geeigneten Materialien und Beeinflussung von wesentlichen Parametern das fügetechnische Problem einer temperaturfesten, vakuumdichten, elektrisch leitenden Verbindung gelöst werden kann. Insbesondere für Sonderfälle, bei denen Messungen an vergleichbaren Massenprodukten unzugänglich bleiben, ist dieser Weg nötig, um Versuchsgefäße zu erhalten und optische Diagnostikverfahren einsetzen zu können.
Kolonneneinbauten zur Vakuumrektifikation
Authors: Zellmer Jörg
Published: July 2007

Der folgende Artikel gibt einen Überblick über gebräuchliche Kolonneneinbauten für die Rektifikation. Es wird die Arbeitsweise von Stoffaustauschböden, Füllkörpern und Strukturpackungen mit besonderem Hinblick, auf den Einsatz im Vakuum beschrieben.
Stabiler korrosionsbeständiger Drucksensor für die chemische Verfahrenstechnik
Authors: Klausmann Lukas
Published: July 2007

Es wird ein keramischer Drucksensor, der nach dem kapazitiven Meßprinzip arbeitet, beschrieben. Dieser Sensor hat sich in unterschiedlichen Anwendungsgebieten, so zum Beispiel in der chemischen Verfahrenstechnik, als präziser und zuverlässig arbeitender Sensor bewährt. Die Vorteile des Sensors werden dargestellt. Als Auswerteelektronik wird ein kundenspezifischer Schaltkreis (ASIC) eingesetzt. Die neuesten Entwicklungen hinsichtlich des Sensorelementes und der Auswerteelektronik werden aufgezeigt. Dadurch ergeben sich für den Sensor neue Applikationsfelder.
Energierückgewinnung bei der Konvektionstrocknung mit Hilfe von Membranen
Authors: Numrich Reiner
Published: July 2007

Die thermische Trocknung von Feststoffen zählt zu den energieintensivsten Verfahrensschritten, da in den meisten Fällen die Rückgewinnung der hohen latenten Wärme des Wassers nicht möglich bzw. nicht wirtschaftlich ist. Insbesondere bei konvektiven Trocknungsverfahren, bei denen Heißgase als Wärmeträger verwendet werden, ist das energetische Niveau der den Trockner verlassenen Brüden sehr niedrig. Ein Ansatzpunkt zur signifikanten Energierückgewinnung bildet die Entwicklung leistungsfähiger Membranen, die eine selektive Abtrennung des Wasserdampfes aus der Abluft ermöglichen. Nach erfolgter Trennung kann der Wasserdampf nach dem Prinzip der mechanischen Brüdenkompression als Heizdampf in den Trocknungsprozeß zurückgeführt werden. An einer Laboranlage konnte die Durchführbarkeit dieses Prozesses nachgewiesen werden. Mit diesem Verfahren ist es möglich, den Energiebedarf bei der Konvektionstrocknung auf ca. 25% des bisher üblichen Bedarfes zu senken. Bezogen auf den Primär‐Energieeinsatz lassen sich Einsparungen bis zu 50% durch Einsatz eines Gasmotors für den erforderlichen Kompressor und die Ausnutzung der Abwärme für den Trocknungsprozeß erreichen.
Dünne Schichten für die Optik und Kristallherstellung in Oberkochen von 1946 bis heute
Authors: Gänswein B.
Published: July 2007

Dünne Schichten für die Optik und das Züchten von optischen Kristallen sind seit ihrem Bestehen untrennbar mit der Hochvakuumtechnik verbunden. Im folgenden wird die Entwicklung dieser Technologien bei Carl Zeiss in Oberkochen in der vergangenen 50 Jahren, also von 1946 bis heute, in Kürze berichtet.
Statische Vakuumentgasungsapparate bei der Herstellung und Qualitätserhöhung von Kunststoffen
Authors: Juvet J. E. , Streiff F. A.
Published: July 2007

Die immer wichtigere Hochentgasung erfordert einen hohen Entgasungswirkungsgrad bis nahe an den Gleichgewichtswert, um die geforderten, tiefen Restmonomerwerte mit wirtschaftlichen und großtechnisch möglichen Betriebsbedingungen erreichen zu können. Wie der folgende Beitrag zeigt, kann dieses Ziel allein mit statischer Entgasung, entgegen üblicher Erwartung, erreicht werden. Kunststoffe mit Viskositäten bis 20000 Pas können noch sicher ausgetragen werden. Dank diesen wesentlichen Prozeßverbesserungen wird sich die statische Entgasung auch in den Bereichen vermehrt verbreiten, in denen sie noch nicht traditionell eingesetzt wird.
The Micro Pirani™: A solid‐state vacuum gauge with wide range
Authors: Wenzel O. , Bak C. K.
Published: July 2007

For measuring pressures in the range 1 × 10−2 to 100 mbar, thermal conductivity gauges are commonly used. The widespread Pirani gauge with a thin wire suffers from problems with temperature drift, low accuracy, requirement for adjustment, large measuring volume, filament contamination, and sensitivity to mounting position. Recently, Wenzel Electronics has introduced the Micro Pirani™, which is based on a newly developed solid‐state sensor element and which eliminates or significantly reduces the problems. A temperature compensation improves the stability and extends the useful range of operation to the high vacuum range at 1 × 10−5 mbar. The geometry of the basic sensor element, close to “infinite slab geometry”, facilitates the introduction of a fairly accurate mathematical model of the sensor. The sensor is insensitive to mounting position since no convection can take place in the sensor due to its small dimensions. Furthermore, the internal volume (“dead volume”) has been significantly reduced as compared to traditional Pirani sensors. The conversion from transmitter output voltage to pressure is achieved by a simple and fast algorithm. The selection of a particular gas species is simple, since the algorithm contains only 3 gas‐dependent constants. An excellent reproducibility in production eliminates the need for an individual calibration of individual sensors in most applications.
Rasterkraftmikroskopie im Vakuum an plasmabehandeltem und metallisiertem Polycarbonat
Authors: Seidel Christian , Gotsmann Bernd , Fuchs Harald
Published: July 2007

Der Artikel beschreibt verschiedene kraftmikroskopische Betriebsarten (statische und dynamische Kraftmikroskopie). Anhand unterschiedlicher Proben, vornehmlich Polycarbonat, wird der Einfluß einer ECR‐Plasmabehandlung sowie von Aluminium‐Beschichtungen gezeigt. Die Plasmabehandlung führt zu einer minimalen Morphologieänderung im nm‐Bereich. Schlecht haftendes Aluminium auf unbehandeltem Polycarbonat konnte nur mittels dynamischer Kraftmikroskopie abgebildet werden.
Dry vacuum pumping technology outperforms oil‐sealed pumps for investment casting
Authors: Westlake Will
Published: July 2007

Feingußverfahren werden zunehmend unter Vakuum durchgeführt. Die dazu bisher eingesetzten ölgedichteten Vakuumpumpen sind in diesem Umfeld sehr wartungsanfällig. Versuche mit trockenlaufenden Klauenvakuumpumpen haben gezeigt, daß dieser Pumpentyp für solche staubbelasteten Anwendungen hervorragend geeignet ist.
Dampfstrahl‐Vakuumpumpen bei der Stahlentgasung
Authors: Teworte R. , Hinrichs F. , Grave H.
Published: July 2007

Die Entgasung von Stahl ist zur Erzeugung spezieller Stahlqualitäten unabdingbar. Bei diesem Prozeß werden besondere Anforderungen an das Saugvermögen und die Robustheit der eingesetzten Vakuumpumpe gestellt, was zum bevorzugten Einsatz von Dampfstrahl‐Vakuumpumpen führt.
Dünnschichten als Targets für den Schwerionenstrahl
Authors: Lommel B.
Published: July 2007

Zur Untersuchung der Wechselwirkung von Materie mit Materie werden beschleunigte lonen auf ein festes Ziel, das Target, geschossen. Dafür kommen freitragende Schichten von wenigen Nanometern bis zu Zentimetern zum Einsatz. Die freitragenden Dünnschichten werden in Hochvakuumaufdampfanlagen auf Träger und wasserlösliche Zwischenschichten abgeschieden und von diesen abgelöst. Als typische Materialien werden neben Kohlenstoff fast alle Metalle, Übergangselemente und viele Seltene Erden verwendet. Neben der chemischen Reinheit ist oft auch die isotopische Reinheit gefordert.
From engineer to scientist: reinventing invention in the Watt and Faraday centenaries, 1919–31
Authors: MACLEOD CHRISTINE , TANN JENNIFER
Published: July 2007

While important research on the history of scientific commemorations has been published in recent years, relatively little attention has been paid to the commemoration of invention and inventors. A comparison of the centenaries of James Watt's death in 1919 and of Michael Faraday's discovery of electromagnetic induction in 1931 reveals how the image of the inventor was being refashioned in the early twentieth century. Although shortly after his death Watt had been acclaimed by the Royal Society as a great ‘natural philosopher’, a century later his reputation had been appropriated by the engineering professions and trades. As the title of Dickinson's 1935 biography described him, he was seen primarily as a ‘craftsman and engineer’, not a scientist. With poor publicity, which failed in particular to make any connection between steam power and electricity, the 1919 centenary excited little interest outside engineering circles. Meanwhile, professional scientists, who were seeking financial recognition for the importance of their research in ‘pure’ science, had found a new icon in Michael Faraday. They seized the occasion of the 1931 centenary to reinforce the link between Faraday's scientific research and the wonders of modern electrical technology and thereby to elevate the role of ‘blue-sky’ research over its ‘mere’ application.
Improvement of nutritional status and incidence of infection in hospitalised, enterally fed elderly by feeding of fermented milk containing probioticLactobacillus johnsoniiLa1 (NCC533)
Authors: Fukushima Yoichi , Miyaguchi Shingo , Yamano Toshihiko , Kaburagi Tomoko , Iino Hisakazu , Ushida Kazunari , Sato Kazuto
Published: July 2007

Probiotics have potential to improve host immunity; however, there is less evidence showing their efficacy against infections and nutritional status in the elderly. We conducted a double-blinded feeding trial in the elderly to elucidate the effect of fermented milk containingLactobacillus johnsoniiLa1 (LC1®) on infections and nutritional status. Twenty-four completely enterally fed elderly in-patients aged over 70 years were randomly assigned into two groups. All subjects were administered 3768 kJ (900 kcal)/d of total enteral nutrition (EN) through tube feeding for 12 weeks. Subjects in the LC1 group were administered 373 kJ (89 kcal)/d of LC1 fermented milk after feeding of 3395 kJ (811 kcal)/d of EN for 12 weeks. In the control group, 373 kJ/d of the same EN was replaced from the fermented milk. In the LC1 group, the percentage of days with infections during the run-in observation period was 15·4 (sd17·3) %, which significantly decreased to 5·7 (sd8·1) % during the intervention period (P = 0·018), and the reduction was larger than that of the control group (P = 0·047). Blood Hb increased (P < 0·05), and there was a tendency towards an increase in serum albumin and a decrease in TNF-α (a pro-inflammatory cytokine) in the LC1 group. There was a trend towards an increase in blood phagocytic activity (a natural immunity marker) in the subjects whose initial level was low in the LC1 group. There were no changes in those parameters in the control group. Administration of fermented milk containing the probioticL. johnsoniiLa1 may contribute to suppressing infections by improving nutritional and immunological status in the elderly.
Beneficial effects of a 5-week low-glycaemic index regimen on weight control and cardiovascular risk factors in overweight non-diabetic subjects
Authors: de Rougemont Alexis , Normand Sylvie , Nazare Julie-Anne , Skilton Michael R. , Sothier Monique , Vinoy Sophie , Laville Martine
Published: July 2007

The glycaemic index (GI) has been developed in order to classify food according to the postprandial glycaemic response. This parameter is of interest, especially for people prone to glucose intolerance; however, the effects of a low-GI (LGI) diet on body weight, carbohydrate and lipid metabolism remain controversial. We studied the effects of either a LGI or high-GI (HGI) diet on weight control and cardiovascular risk factors in overweight, non-diabetic subjects. The study was a randomized 5-week intervention trial. The thirty-eight subjects (BMI 27·3 (sem0·2) kg/m2) followed an intervention diet in which usual starch was replacedad libitumwith either LGI or HGI starch. Mean body weight decrease was significant in the LGI group ( − 1·1 (sEM0·3) kg,P = 0·004) and was significantly greater than in the HGI group ( − 0·3 (sEM0·2) kg,P = 0·04 between groups). Hunger sensation scales showed a trend towards a decrease in hunger sensation before lunch and dinner in the LGI group when compared with the HGI group (P = 0·09). No significant increase in insulin sensitivity was noticed. The LGI diet also decreased total cholesterol by 9·6 % (P < 0·001), LDL-cholesterol by 8·6 % (P = 0·01) and both LDL-:HDL-cholesterol ratio (10·1 %,P = 0·003) and total:HDL-cholesterol ratio (8·5 %,P = 0·001) while no significant changes were observed in the HGI group. Lowering the GI of daily meals with simple dietary recommendations results in increased weight loss and improved lipid profile and is relatively easy to implement with few constraints. These potential benefits of consuming a LGI diet can be useful to develop practical dietetic advice.
Changes in the phenolic content of low density lipoprotein after olive oil consumption in men. A randomized crossover controlled trial
Authors: Gimeno Eva , de la Torre-Carbot Karina , Lamuela-Raventós Rosa M. , Castellote Ana I. , Fitó Montserrat , de la Torre Rafael , Covas María-Isabel , Carmen López-Sabater M.
Published: July 2007

Olive oil decreases the risk of CVD. This effect may be due to the fatty acid profile of the oil, but it may also be due to its antioxidant content which differs depending on the type of olive oil. In this study, the concentrations of oleic acid and antioxidants (phenolic compounds and vitamin E) in plasma and LDL were compared after consumption of three similar olive oils, but with differences in their phenolic content. Thirty healthy volunteers participated in a placebo-controlled, double-blind, crossover, randomized supplementation trial. Virgin, common, and refined olive oils were administered during three periods of 3 weeks separated by a 2-week washout period. Participants were requested to ingest a daily dose of 25 ml raw olive oil, distributed over the three meals of the day, during intervention periods. All three olive oils caused an increase in plasma and LDL oleic acid (P < 0·05) content. Olive oils rich in phenolic compounds led to an increase in phenolic compounds in LDL (P < 0·005). The concentration of phenolic compounds in LDL was directly correlated with the phenolic concentration in the olive oils. The increase in the phenolic content of LDL could account for the increase of the resistance of LDL to oxidation, and the decrease of thein vivooxidized LDL, observed in the frame of this trial. Our results support the hypothesis that a daily intake of virgin olive oil promotes protective LDL changes ahead of its oxidation.
Shang ritual animals: colour and meaning (part 1)
Authors: Tao Wang
Published: July 2007

This paper (to be published in two parts in subsequent issues of BSOAS) aims to explore the meaning of colour in Shang rituals. Operating within an established framework of Shang religion and archaeology, it offers a detailed analysis of the evidence found in oracle bone inscriptions. The oracle bone inscriptions from Yinxu, the late capital of the Shang dynasty, can be divided into different diviner schools and subgroups. Part 1 of the paper will examine the inscriptions of the various diviner groups under the kings' school, and will reveal regular patterns in the use of colour.
Transnational theories of order and change: heterodoxy in International Relations scholarship
Authors: PALAN RONEN
Published: July 2007

In this article I argue that the very meaning of ‘inter-national relations’ is emerging as a focus of debate in International Relations, particularly among the critical traditions in the discipline. No longer seen as a mere study of peace and war, IR is viewed as a component of general pan-disciplinary theories or order and change. The international sphere is perceived, accordingly, no longer as a system in its own right, but rather as a gigantic transmission belt, and a huge communication device transmitting and diffusing ideas, practices, rules, norms and institutions throughout the world. The article examines the implications of such an approach on IR theory. In addition, the article revisits the works of Hegel, Marx and the French School of Regulation to demonstrate how they developed an empirical theory of international diffusion.
Happy Anniversary! Time and critique in International Relations theory
Authors: HUTCHINGS KIMBERLY
Published: July 2007

All critical theories lay claim to some kind of account not only of the present of international politics and its relation to possible futures, but also of the role of critical theory in the present and future in international politics. This article argues that if critical international theory is to have a future that lives up to its revolutionary ambition, then it needs to listen more carefully to the voices of postcolonial and feminist critics and take on board the heterotemporality of international politics.
Homogenization of singularly perturbed Dirichlet problems in perforated domains
Authors: Hoáng Viêt Há
Published: July 2007

We study the singularly perturbed problem —εαΔuε + uε = f (α > 0) with the Dirichlet boundary condition in a perforated domain, in which the holes are distributed periodically with period 2ε throughout a fixed domain Ω. The asymptotic behaviour of uε when ε → 0, together with corrector results and error estimates in L2(Ω), are deduced for all sizes of holes. The behaviour of uε in is obtained for the cases where the size of holes is of order ε or is of a sufficiently smaller order. When the holes' size is of a sufficiently small order, as expected, uε has similar behaviour to that in the case of a non-varying domain.
Non-existence of solutions for some nonlinear elliptic equations involving measures
Authors: Orsina L. , Prignet A.
Published: July 2007

In this paper, we study the non-existence of solutions for the following (model) problem in a bounded open subset Ω of RN:

with Dirichlet boundary conditions, where p > 1, q > 1 and μ is a bounded Radon measure. We prove that if λ is a measure which is concentrated on a set of zero r capacity (p < r ≤ N), and if q > r (p − 1)/(r − p), then there is no solution to the above problem, in the sense that if one approximates the measure λ with a sequence of regular functions fn, and if un is the sequence of solutions of the corresponding problems, then un converges to zero.

We also study the non-existence of solutions for the bilateral obstacle problem with datum a measure λ concentrated on a set of zero p capacity,

with u in for every υ in K, finding again that the only solution obtained by approximation is u = 0.
The limit case of the Cesàro-α convergence of the ergodic averages and the ergodic Hilbert transform
Authors: Bernardis A. L. , Martín-Reyes F. J.
Published: July 2007

Recently, Sarrión and the authors gave a sufficient condition on invertible Lamperti operators on Lp which guarantees the convergence in the Cesàro-α sense of the ergodic averages and the ergodic Hilbert transform for all f ∈ Lp with p > 1/(1 + α) and −1 < α ≤ 0. The result does not hold for the space L1/(1 + α). In this paper we give a positive result for the smaller Lorentz space L1/(1 + α),1.
Sturm–Liouville problems with non-separated eigenvalue dependent boundary conditions
Authors: Binding P. A. , Browne P. J.
Published: July 2007

Sturm–Liouville differential equations are studied under non-separated boundary conditions whose coefficients are first degree polynomials in the eigenparameter. Situations are examined where there are at most finitely many non-real eigenvalues and also where there are only finitely many real ones.
Linear quasi-differential operators in locally integrable spaces on the real line
Authors: Ashurov R. R. , Everitt W. N.
Published: July 2007

The theory of ordinary linear quasi-differential expressions and operators has been extensively developed in integrable-square Hilbert spaces. There is also an extensive theory of ordinary linear differential expressions and operators in integrable-p Banach spaces.

However, the basic definition of linear quasi-differential expressions involves Lebesgue locally integrable spaces on intervals of the real line. Such spaces are not Banach spaces but can be considered as complete locally convex linear topological spaces where the topology is derived from a countable family of semi-norms. The first conjugate space can also be defined as a complete locally convex linear topological space, but now with the topology derived as a strict inductive limit.

This paper develops the properties of linear quasi-differential operators in a locally integrable space and the first conjugate space. Conjugate and preconjugate operators are defined in, respectively, dense and total domains.
Quantitative continuation from a measurable set of solutions of elliptic equations
Authors: Vessella S.
Published: July 2007

Consider an open bounded connected set Ω in Rn and a Lebesgue measurable set E ⊂⊂ Ω of positive measure. Let u be a solution of the strictly elliptic equation Di (aij Dj u) = 0 in Ω, where aij ∈ C0, 1 (Ω̄) and {aij} is a symmetric matrix. Assume that |u| ≤ ε in E. We quantify the propagation of smallness of u in Ω.
Exponential bases in Sobolev spaces in control and observation problems for the wave equation
Authors: Avdonin S. A. , Ivanov S. A. , Russell D. L.
Published: July 2007

The Fourier method in control systems reduces the study of controllability/observability to the study of related exponential families. In this paper we present examples of such systems, specifically those for which we can prove that the related exponential families form a Riesz basis in corresponding appropriately defined Sobolev spaces. This makes it possible to choose ‘natural’ pairs of spaces: the state space observability space and the control space state space, depending on whether an observation or a control problem is studied, respectively, so that the observation and control operators are isomorphisms.
Two-parameter right definite Sturm—Liouville problems with eigenparameter-dependent boundary conditions
Authors: Bhattacharyya T. , Binding P. A. , Seddighi K.
Published: July 2007

Linked equations

are studied on [0,1] subject to boundary conditions of the form

Results are given on existence, location, asymptotics and perturbation of the eigenvalues λj and oscillation of the eigenfunctions yi.
Solutions for the Cahn—Hilliard equation with many boundary spike layers
Authors: Wei Juncheng , Winter Matthias
Published: July 2007

In this paper we construct new classes of stationary solutions for the Cahn–Hilliard equation by a novel approach.

One of the results is as follows. Given a positive integer K and a (not necessarily non-degenerate) local minimum point of the mean curvature of the boundary, then there are boundary K-spike solutions whose peaks all approach this point. This implies that for any smooth and bounded
domain there exist boundary K-spike solutions.

The central ingredient of our analysis is the novel derivation and exploitation of a reduction of the energy to finite dimensions (lemma 3.5), where the variables are closely related to the peak locations.
On Iterated Image Size for Point-Symmetric Relations
Authors: HAMIDOUNE YAHYA OULD
Published: July 2007

Let Γ =(V,E) be a point-symmetric reflexive relation and let υ ∈ V such that |Γ(υ)| is finite (and hence |Γ(x)| is finite for all x, by the transitive action of the group of automorphisms). Let j ∈ℕ be an integer such that Γj(υ)∩ Γ−(υ)={υ}. Our main result states that

As an application we have |Γj(υ)| ≥ 1+(|Γ(υ)|−1)j. The last result confirms a recent conjecture of Seymour in the case of vertex-symmetric graphs. Also it gives a short proof for the validity of the Caccetta–Häggkvist conjecture for vertex-symmetric graphs and generalizes an additive result of Shepherdson.
OPTIMAL DYNAMIC LABOR TAXATION
Authors: BASU PARANTAP , RENSTRÖM THOMAS I.
Published: July 2007

We analyze optimal dynamic taxation when labor supply is indivisible. As in Hansen (1985) and Rogerson (1988), markets are complete, and an employment lottery determines who works. The consumer can buy insurance to diversify this income uncertainty. The optimal wage tax is generally positive except for some special cases when leisure is nonnormal and the government can use debt as a policy instrument in addition to its tax instruments. We derive a HARA class of preferences, for which we characterize the dynamic paths of the wage tax. The optimal paths of the labor tax differ between divisible- and indivisible-labor economies.
Enhancement of coastal upwelling and interdecadal ENSO‐like variability in the Peru‐Chile Current since late 19th century
Authors: Vargas Gabriel , Pantoja Silvio , Rutllant José A. , Lange Carina B. , Ortlieb Luc
Published: July 2007

Secular trends in coastal upwelling proxies from a sediment record at 23°S encompassing 250 years reveal two distinct stages separated by a transition period between AD 1820 and 1878. Persistent interdecadal variability that roughly follows the Pacific Decadal Oscillation is accompanied by intensification of upwelling‐favourable coastal winds and decreased coastal sea surface temperature since AD 1878. We propose that an increased land‐sea thermal contrast along the arid coast of northern Chile and Peru intensifies the equatorward wind stress due to reduced mean low‐cloud cover, resulting in enhanced primary and export production during interdecadal El Niño‐like conditions. This mechanism overcompensates for the overall effect of a regional surface warming secular trend in the Peru‐Chile Current System, providing a novel insight on physical and biogeochemical feedbacks of coastal upwelling ecosystems to global warming.
Global distortion of GPS networks associated with satellite antenna model errors
Authors: Cardellach E. , Elósegui P. , Davis J. L.
Published: July 2007

Recent studies of the GPS satellite phase center offsets (PCOs) suggest that these have been in error by ∼1 m. Previous studies had shown that PCO errors are absorbed mainly by parameters representing satellite clock and the radial components of site position. On the basis of the assumption that the radial errors are equal, PCO errors will therefore introduce an error in network scale. However, PCO errors also introduce distortions, or apparent deformations, within the network, primarily in the radial (vertical) component of site position that cannot be corrected via a Helmert transformation. Using numerical simulations to quantify the effects of PCO errors, we found that these PCO errors lead to a vertical network distortion of 6–12 mm per meter of PCO error. The network distortion depends on the minimum elevation angle used in the analysis of the GPS phase observables, becoming larger as the minimum elevation angle increases. The steady evolution of the GPS constellation as new satellites are launched, age, and are decommissioned, leads to the effects of PCO errors varying with time that introduce an apparent global‐scale rate change. We demonstrate here that current estimates for PCO errors result in a geographically variable error in the vertical rate at the 1–2 mm yr−1level, which will impact high‐precision crustal deformation studies.
Coupled and noncoupled behavior of three‐dimensional morphological patterns in a double sandbar system
Authors: Ruessink B. G. , Coco Giovanni , Ranasinghe Roshanka , Turner Ian L.
Published: July 2007

Eight weeks of daily (low tide) time exposure images of the Gold Coast (Australia) were used to analyze the development of three‐dimensional morphological patterns in a double sandbar system. Under continued low‐energy wave conditions following a morphological reset (storm) event, the patterns in both the inner and outer bar evolved, albeit at different spatial and temporal scales, through the accretionary sequence commonly observed at single barred beaches. Continuous wavelet transforms (CWT) of the inner bar and outer bar breaker lines show that after a storm the patterns developed at a wide range of alongshore wavelengths and that variations in wavelength over space and time were common. With the bivariate extension of CWT, continuous cross‐wavelet transforms, it is found that the initial inner bar and outer bar three‐dimensional patterns were spatially noncoupled. However, over time the inner‐bar morphology appeared to couple with that of the outer bar, with the inner bar patterns developing in response to the increasingly three‐dimensional, onshore propagating outer bar. The wavelet analysis suggests that the outer bar geometry and the distance between the inner and outer bars are critical parameters governing the morphological evolution of the composite double sandbar system.
Microstructural evolution within a partitioned midcrustal transpression zone, northeast Greenland Caledonides
Authors: Smith S. A. F. , Strachan R. A. , Holdsworth R. E.
Published: July 2007

The thrust‐related Imbricate Zone and the sinistral strike‐slip Storstrømmen Shear Zone (SSZ) are two major orogen‐parallel ductile shear zones that mark the western limit of intense Caledonian deformation in northeast Greenland and transect the orogenic hinterland, respectively. Detailed microstructural analysis of associated mylonitic fault rocks from Dronning Louise Land and Hertugen af Orléans Land has been carried out to provide insights into the evolution of these structures and to constrain the relative timing of movement. Amphibolite‐facies mylonites were developed across the entire ca. 8‐km‐wide SSZ and are currently exposed across an area ca. 3–4 km wide within the center of the shear zone. In contrast, retrograde greenschist‐facies mylonites are concentrated within a ca. 2‐ to 4‐km‐wide belt along the western margin of the shear zone. This metamorphic pattern is interpreted to reflect progressive localization of strain associated with exhumation and syntectonic cooling. The ca. 15‐km‐wide Imbricate Zone consists of numerous east‐dipping ductile thrust sheets. At low structural levels, mylonitic fabrics indicate that thrust‐related deformation occurred at middle‐greenschist facies. Toward higher levels, however, microstructures suggest that the metamorphic grade progressively increases. We propose that ductile thrusting across the Imbricate Zone was synchronous with uplift and exhumation of the orogenic hinterland and SSZ, accounting for the observed metamorphic variations. This implies that both structures were active broadly contemporaneously during regional partitioned transpression, an inference supported by scattered 40Ar/39Ar and recent U‐Pb zircon ages. The microstructural observations therefore support models that involve sinistrally oblique Silurian‐Devonian collision between Laurentia and Baltica.
Stochastic downscaling of precipitation: From dry events to heavy rainfalls
Authors: Vrac M. , Naveau P.
Published: July 2007

Downscaling precipitation is a difficult challenge for the climate community. We propose and study a new stochastic weather typing approach to perform such a task. In addition to providing accurate small and medium precipitation, our procedure possesses built‐in features that allow us to model adequately extreme precipitation distributions. First, we propose a new distribution for local precipitation via a probability mixture model of Gamma and Generalized Pareto (GP) distributions. The latter one stems from Extreme Value Theory (EVT). The performance of this mixture is tested on real and simulated data, and also compared to classical rainfall densities. Then our downscaling method, extending the recently developed nonhomogeneous stochastic weather typing approach, is presented. It can be summarized as a three‐step program. First, regional weather precipitation patterns are constructed through a hierarchical ascending clustering method. Second, daily transitions among our precipitation patterns are represented by a nonhomogeneous Markov model influenced by large‐scale atmospheric variables like NCEP reanalyses. Third, conditionally on these regional patterns, precipitation occurrence and intensity distributions are modeled as statistical mixtures. Precipitation amplitudes are assumed to follow our mixture of Gamma and GP densities. The proposed downscaling approach is applied to 37 weather stations in Illinois and compared to various possible parameterizations and to a direct modeling. Model selection procedures show that choosing one GP distribution shape parameter per pattern for all stations provides the best rainfall representation amongst all tested models. This work highlights the importance of EVT distributions to improve the modeling and downscaling of local extreme precipitations.
Capillary pressure as a unique function of electric permittivity and water saturation
Authors: Plug Willem‐Jan , Slob Evert , van Turnhout Jan , Bruining Johannes
Published: July 2007

The relation between capillary pressure (Pc) and interfacial area has been investigated by measuring Pc and the electric permittivity at 100 kHz simultaneously as function of the water saturation, (Sw). Drainage and imbibition experiments have been conducted for sand‐distilled water‐gas (CO2/N2) systems. The main capillary cycles and the scanning curves show hysteresis with the drainage curves displaying higher values than the imbibition curves. The 100 kHz permittivity data also show hysteresis between drainage and imbibition. Furthermore non‐monotonic behavior is observed, which is analogous to the interfacial area characteristics obtained from network and micro‐pore models. The permittivity behavior is attributed to polarization of the gas‐water and water‐solid interfaces. The permittivity hysteresis is provoked by the different phase distributions and geometries. Our results show that Pc is a unique function of the permittivity and Sw, and therefore this work provides clear evidence that the permittivity is a measure for the interfacial area.
GRACE detects coseismic and postseismic deformation from the Sumatra‐Andaman earthquake
Authors: Chen J. L. , Wilson C. R. , Tapley B. D. , Grand S.
Published: July 2007

We show that spherical harmonic (SH) solutions of the Gravity Recovery and Climate Experiment (GRACE) are now of sufficient quality to observe effects of co‐seismic and post‐seismic deformation due to the rupture from the Mw = 9.3 Sumatra‐Andaman earthquake on December 26, 2004, and its companion Nias earthquake (Mw = 8.7) on March 28, 2005. The improved GGM 03 SH (Level 2) solutions, and improved filtering methods provide estimates with spatial resolution comparable to earlier estimates from range‐rate (Level 1) GRACE data. The gravity field disturbance extends over 1800 km along Andaman and Sunda subduction zones, and changes with time following events. Gravity changes may be due to afterslip, viscoelastic relaxation, or other processes associated with dilatation. Satellite gravity measurements from GRACE provide a unique new measure of deformation and post‐seismic processes associated with major earthquakes, especially in areas which are primarily oceanic.
Human African trypanosomiasis: pharmacological re‐engagement with a neglected disease
Authors: Barrett M P , Boykin D W , Brun R , Tidwell R R
Published: July 2007

This review discusses the challenges of chemotherapy for human African trypanosomiasis (HAT). The few drugs registered for use against the disease are unsatisfactory for a number of reasons. HAT has two stages. In stage 1 the parasites proliferate in the haemolymphatic system. In stage 2 they invade the central nervous system and brain provoking progressive neurological dysfunction leading to symptoms that include the disrupted sleep wake patterns that give HAT its more common name of sleeping sickness. Targeting drugs to the central nervous system offers many challenges. However, it is the cost of drug development for diseases like HAT, that afflict exclusively people of the world's poorest populations, that has been the principal barrier to new drug development and has led to them becoming neglected. Here we review drugs currently registered for HAT, and also discuss the few compounds progressing through clinical trials. Finally we report on new initiatives that might allow progress to be made in developing new and satisfactory drugs for this terrible disease.

British Journal of Pharmacology(2007)152, 1155–1171; doi:10.1038/sj.bjp.0707354; published online 9 July 2007
Good statistical practice in pharmacology Problem 1
Authors: Lew M
Published: July 2007

Background and purpose:

This paper is intended to assist pharmacologists in making the most of statistical analysis and in avoiding common errors that can lead to false conclusions.

Approach:

A scenario is presented where a pathway inhibitor increased blood pressure responses to an agonist by about one third. The fictional experimenter concludes that the inhibitor enhanced the responses to the agonist, but has not applied any statistical analysis. Questions are asked of the reader, and a discussion of the author's answers is presented.

Results:

The agonist responses have unequal standard errors, as often seen in data like these concentration‐response curves with responses expressed as change from baseline. The uneven variability (heteroscedasticity) violates an assumption of conventional parametric statistical analyses, but can be corrected by data transformation. Expressing the data as absolute blood pressure and then transforming it to log blood pressure eliminated the heteroscedasticity, but made evident an effect of the inhibitor on baseline blood pressure.

Conclusions and implications:

Statistical analysis is a sensible precaution against mistakes, but cannot protect against all erroneous conclusions. In this scenario, the inhibitor reduced the blood pressure and increased responses to the agonist. However, it is likely that the latter effect was a consequence of the former and thus no conclusion can be safely drawn about any direct interaction between the agonist and the pathway inhibitor from this experiment. Where results are awkward to interpret because of confounding factors such as an altered baseline, statistical analysis may not be very useful in supporting a safe conclusion.

British Journal of Pharmacology (2007) 152, 295–298; doi:10.1038/sj.bjp.0707370; published online 9 July 2007