Resonant motions in the presence of degeneracies for quasi-periodically perturbed systems

We consider one-dimensional systems in the presence of a quasi-periodic perturbation, in the analytical setting, and study the problem of existence of quasi-periodic solutions which are resonant with the frequency vector of the perturbation. We assume that the unperturbed system is locally integrable and anisochronous, and that the frequency vector of the perturbation satisfies the Bryuno condition. Existence of resonant solutions is related to the zeroes of a suitable function, called the Melnikov function - by analogy with the periodic case. We show that, if the Melnikov function has a zero of odd order and under some further condition on the sign of the perturbation parameter, then there exists at least one resonant solution which continues an unperturbed solution. If the Melnikov function is identically zero then one can push perturbation theory up to the order where a counterpart of Melnikov function appears and does not vanish identically: if such a function has a zero of odd order and a suitable positiveness condition is met, again the same persistence result is obtained. If the system is Hamiltonian, then the procedure can be indefinitely iterated and no positiveness condition must be required: as a byproduct, the result follows that at least one resonant quasi-periodic solution always exists with no assumption on the perturbation. Such a solution can be interpreted as a (parabolic) lower-dimensional torus.Comment: 60 pages, 16 figures. arXiv admin note: substantial text overlap with arXiv:1011.093

Path-creating networks in the field of next generation lithography: outline of a research project

Der Beitrag stellt ein Forschungsprojekt vor, das die möglichen technologischen Pfade bei der Entwicklung von Halbleitern untersucht, die schließlich zu einer Produktion, also zu einer Umsetzung des technologischen Fortschritts, führen. An solch einem Vorgang sind Personen mit unterschiedlichem wissenschaftlichem Hintergrund (optische Physik, Elektrotechnik, Chemie) und verschiedene Gesellschaftsbereiche (Wissenschaft, Wirtschaft, Staat) beteiligt. In diesem Zusammenhang stellt sich nun die Ausgangsfrage des Projektes, in welchem Umfang, unter welchen Bedingungen und Organisations-Netzwerken die Kreation eines neuen technologischen Pfades möglich ist. In das Thema einführend, wird zunächst der Forschungsstand zum Zusammenhang zwischen der Theorie der Pfadabhängigkeit und dem Konzept der Pfadkreation im Prozess der Technologieentwicklung beschrieben. Auf dieser Grundlage folgt die Konzeptionalisierung des dargestellten Forschungsprojektes. Im Anschluss wird das empirische Untersuchungsfeld in seinen Grundzügen präsentiert: die Entwicklung einer neuen Lithographie-Generation für Halbleiter mit besonderer Berücksichtigung der unterschiedlichen technologischen Pfade, die als realisierbar anzusehen sind. So gilt es, bei der Betrachtung der Pfadkreation von technologischen Neuerungen die Entwicklung reflexiver interorganisationaler Netzwerke zu betrachten. Gemäß der spezifischen Forschungsfragen werden abschließend das Forschungsdesign und die methodologische Vorgehensweise präsentiert. So ist das Projekt auf den Zeitraum von 2004 bis 2009 zugeschnitten und umfasst drei Interviewphasen. Auf diese Weise kann der Innovationsprozess der nächsten Lithographie-Generation in Realzeit bis zur voraussichtlichen Produktion dieser neuen Systemtechnologie untersucht werden. (ICG2

The Case of Semiconductor Manufacturing Technologies

Taking issue with the classical theory of path dependence, we capture the active agency involved in collective efforts aimed at extending a current technological path and, in parallel, at creating a new path in the field of leading-edge international semiconductor manufacturing. We apply structuration theory in order to analyse the practices of path constitution that traditional evolutionary views of lock-in and irreversibility in path processes have neglected. Drawing on 96 interviews since 2003 and extensive secondary sources in the field of semiconductor manufacturing in Europe, Japan and the United States, we perform a qualitative, longitudinal and multi-level case analysis; in this analysis we trace, in particular, the strategic development of a path- extending technological option besides a potentially path-breaking new generation of lithography for chip manufacturing systems. Our results provide deep insights into the collective and collaborative dimension of organizing R&D; in processes of technology development. Thereby, we contribute to a theory of technological paths that considers collective embedded agency and takes into account interorganizational forms for an understanding of the innovation dynamics in science-based industries such as semiconductor manufacturing

Organizing R&D Consortia for Path Creation and Extension: The Case of Semiconductor Manufacturing Technologies

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Taking issue with the classical theory of path dependence, we capture the active agency involved in collective efforts aimed at extending a current technological path and, in parallel, at creating a new path in the field of leading-edge international semiconductor manufacturing. We apply structuration theory in order to analyse the practices of path constitution that traditional evolutionary views of lock-in and irreversibility in path processes have neglected. Drawing on 96 interviews since 2003 and extensive secondary sources in the field of semiconductor manufacturing in Europe, Japan and the United States, we perform a qualitative, longitudinal and multi-level case analysis; in this analysis we trace, in particular, the strategic development of a path-extending technological option besides a potentially path-breaking new generation of lithography for chip manufacturing systems. Our results provide deep insights into the collective and collaborative dimension of organizing R&D in processes of technology development. Thereby, we contribute to a theory of technological paths that considers collective embedded agency and takes into account interorganizational forms for an understanding of the innovation dynamics in science-based industries such as semiconductor manufacturing

Self-Activation of Inorganic-Organic Hybrids Derived through Continuous Synthesis of Polyoxomolybdate and para-Phenylenediamine Enables Very High Lithium-Ion Storage Capacity

Inorganic-organic hybrid materials with redox-active components were prepared by an aqueous precipitation reaction of ammonium heptamolybdate (AHM) with para-phenylenediamine (PPD). A scalable and low-energy continuous wet chemical synthesis process, known as the microjet process, was used to prepare particles with large surface area in the submicrometer range with high purity and reproducibility on a large scale. Two different crystalline hybrid products were formed depending on the ratio of molybdate to organic ligand and pH. A ratio of para-phenylenediamine to ammonium heptamolybdate from 1 : 1 to 5 : 1 resulted in the compound [C6H10N2]2[Mo8O26] ⋅ 6 H2O, while higher PPD ratios from 9 : 1 to 30 : 1 yielded a composition of [C6H9N2]4[NH4]2[Mo7O24] ⋅ 3 H2O. The electrochemical behavior of the two products was tested in a battery cell environment. Only the second of the two hybrid materials showed an exceptionally high capacity of 1084 mAh g−1 at 100 mA g−1 after 150 cycles. The maximum capacity was reached after an induction phase, which can be explained by a combination of a conversion reaction with lithium to Li2MoO4 and an additional in situ polymerization of PPD. The final hybrid material is a promising material for lithium-ion battery (LIB) applications

"Demokratielernen konkret" am Beispiel des schweizerischen Lehrmittels URwegs

Das Lehrmittel URwegs steht im Fokus des Beitrags. Die Autor*innen verdeutlichen, wie mit diesem ein Demokratielernen der Schüler*innen konkretisiert werden kann und Lehrkräfte in ihrem Unterricht unterstützt werden können. Demokratie wird i. S. von Himmelmann mehrdimensional als Lebens-, Gesellschafts- und Herrschaftsform verstanden, die die didaktischen Grundsätze des Lehrmittels – auch im Rekurs zur Verortung im deutschschweizerischen Lehrplans 21 – formen. Dabei steht vor allem ein Lebensweltbezug im Fokus. (DIPF/Orig.

Validation of putative reference genes for gene expression studies in human hepatocellular carcinoma using real-time quantitative RT-PCR

<p>Abstract</p> <p>Background</p> <p>Reference genes, which are often referred to as housekeeping genes are frequently used to normalize mRNA levels between different samples in quantitative reverse transcription polymerase chain reaction (qRT-PCR). The selection of reference genes is critical for gene expression studies because the expression of these genes may vary among tissues or cells and may change under certain circumstances. Here, a systematic evaluation of six putative reference genes for gene expression studies in human hepatocellular carcinoma (HCC) is presented.</p> <p>Methods</p> <p>Six genes, beta-2-microglobulin (<it>B2M</it>), glyceraldehyde-3-phosphate dehydrogenase (<it>GAPDH</it>), hydroxymethyl-bilane synthase (<it>HMBS</it>), hypoxanthine phosphoribosyl-transferase 1 (<it>HPRT1</it>), succinate dehydrogenase complex, subunit A (<it>SDHA</it>) and ubiquitin C (<it>UBC</it>), with distinct functional characteristics and expression patterns were evaluated by qRT-PCR. Inhibitory substances in RNA samples were quantitatively assessed and controlled using an external RNA control. The stability of selected reference genes was analyzed using both <it>geNorm </it>and <it>NormFinder </it>software.</p> <p>Results</p> <p><it>HMBS </it>and <it>GAPDH </it>were identified as the optimal reference genes for normalizing gene expression data between paired tumoral and adjacent non-tumoral tissues derived from patients with HCC. <it>HMBS, GAPDH </it>and <it>UBC </it>were identified to be suitable for the normalization of gene expression data among tumor tissues; whereas the combination of <it>HMBS, B2M</it>, <it>SDHA </it>and <it>GAPDH </it>was suitable for normalizing gene expression data among five liver cancer cell lines, namely Hep3B, HepG2, HuH7, SK-HEP-1 and SNU-182. The determined gene stability was increased after exclusion of RNA samples containing relatively higher inhibitory substances.</p> <p>Conclusion</p> <p>Of six genes studied, <it>HMBS </it>was found to be the single best reference gene for gene expression studies in HCC. The appropriate choice of combination of more than one reference gene to improve qRT-PCR accuracy depends on the kind of liver tissues or cells under investigation. Quantitative assessment and control of qRT-PCR inhibitors using an external RNA control can reduce the variation of qRT-PCR assay and facilitate the evaluation of gene stability. Our results may facilitate the choice of reference genes for expression studies in HCC.</p

Malaria diagnostic testing and treatment practices in three different Plasmodium falciparum transmission settings in Tanzania: before and after a government policy change

BACKGROUND: Patterns of decreasing malaria transmission intensity make presumptive treatment of malaria an unjustifiable approach in many African settings. The controlled use of anti-malarials after laboratory confirmed diagnosis is preferable in low endemic areas. Diagnosis may be facilitated by malaria rapid diagnostic tests (RDTs). In this study, the impact of a government policy change, comprising the provision of RDTs and advice to restrict anti-malarial treatment to RDT-positive individuals, was assessed by describing diagnostic behaviour and treatment decision-making in febrile outpatients <10 years of age in three hospitals in the Kagera and Mwanza Region in northern Tanzania. METHODS: Prospective data from Biharamulo and Rubya Designated District Hospital (DDH) were collected before and after policy change, in Sumve DDH no new policy was implemented. Diagnosis of malaria was confirmed by RDT; transmission intensity was evaluated by a serological marker of malaria exposure in hospital attendees. RESULTS: Prior to policy change, there was no evident association between the actual level of transmission intensity and drug-prescribing behaviour. After policy change, there was a substantial decrease in anti-malarial prescription and an increase in prescription of antibiotics. The proportion of parasite-negative individuals who received anti-malarials decreased from 89.1% (244/274) to 38.7% (46/119) in Biharamulo and from 76.9% (190/247) to 10.0% (48/479) in Rubya after policy change. CONCLUSION: This study shows that an official policy change, where RDTs were provided and healthcare providers were advised to adhere to RDT results in prescribing drugs can be followed by more rational drug-prescribing behaviour. The current findings are promising for improving treatment policy in Tanzanian hospitals