Is Double Trouble? – How to Combine Cointegration Tests

This paper suggests a combination procedure to exploit the imperfect correlation of cointegration tests to develop a more powerful meta test.To exemplify, we combine Engle and Granger (1987) and Johansen (1988) tests. Either of these underlying tests can be more powerful than the other one depending on the nature of the data-generating process. The new meta test is at least as powerful as the more powerful one of the underlying tests irrespective of the very nature of the data generating process. At the same time, our new meta test avoids the arbitrary decision which test to use if single test results conflict. Moreover it avoids the size distortion inherent in separately applying multiple tests for cointegration to the same data set. We apply our test to 143 data sets from published cointegration studies. There, in one third of all cases single tests give conflicting results whereas our meta test provides an unambiguous test decision.Cointegration, meta test, multiple testing

Is Double Trouble? How to Combine Cointegration Tests

This paper suggests a combination procedure to exploit the imperfect correlation of cointegration tests to develop a more powerful meta test. To exemplify, we combine Engle and Granger (1987) and Johansen (1988) tests. Either of these underlying tests can be more powerful than the other one depending on the nature of the data-generating process. The new meta test is at least as powerful as the more powerful one of the underlying tests irrespective of the very nature of the data generating process. At the same time, our new meta test avoids the arbitrary decision which test to use if single test results conflict. Moreover it avoids the size distortion inherent in separately applying multiple tests for cointegration to the same data set. We apply our test to 143 data sets from published cointegration studies. There, in one third of all cases single tests give conflicting results whereas our meta tests provides an unambiguous test decision.Economics ;

Is double trouble? How to combine cointegration tests

This paper suggests a combination procedure to exploit the imperfect correlation of cointegration tests to develop a more powerful meta test. To exemplify, we combine Engle and Granger (1987) and Johansen (1988) tests. Either of these underlying tests can be more powerful than the other one depending on the nature of the data-generating process. The new meta test is at least as powerful as the more powerful one of the underlying tests irrespective of the very nature of the data generating process. At the same time, our new meta test avoids the size distortion inherent in separately applying multiple tests for cointegration to the same data set. --Cointegration,Meta Test,Multiple Testing

Characterization of High Temperature Superconductor Cables for Magnet Toroidal Field Coils of the DEMO Fusion Power Plant

Nuclear fusion is a key technology to satisfy the basic demand for electric energy sustainably. The official EUROfusion schedule foresees a first industrial DEMOnstration Fusion Power Plant for 2050. In this work several high temperature superconductor sub-size cables are investigated for their applicability in large scale DEMO toroidal field coils. Main focus lies on the electromechanical stability under the influence of high Lorentz forces at peak magnetic fields of up to 12 T

Is double trouble? How to combine cointegration tests

This paper suggests a combination procedure to exploit the imperfect correlation of cointegration tests to develop a more powerful meta test. To exemplify, we combine Engle and Granger (1987) and Johansen (1988) tests. Either of these un- derlying tests can be more powerful than the other one depending on the nature of the data-generating process. The new meta test is at least as powerful as the more powerful one of the underlying tests irrespective of the very nature of the data generating process. At the same time, our new meta test avoids the size distortion inherent in separately applying multiple tests for cointegration to the same data set

NmPin from the marine thaumarchaeote Nitrosopumilus maritimus is an active membrane associated prolyl isomerase.

We cordially thank Alma Rute for excellent technical assistance and the DFG (GRK 1431-1 and 1431-2) for financial support (PB). We thank the Microscope and Histology Facility of the University of Aberdeen for providing their equipment. We also thank Jacob Hargreaves for proofreading the manuscript.Peer reviewedPublisher PD

Temperature- and Field Dependent Characterization of a Twisted Stacked-Tape Cable

The Twisted Stacked-Tape Cable (TSTC) is one of the major high temperature superconductor cable concepts combining scalability, ease of fabrication and high current density making it a possible candidate as conductor for large scale magnets. To simulate the boundary conditions of such a magnets as well as the temperature dependence of Twisted Stacked-Tape Cables a 1.16 m long sample consisting of 40, 4 mm wide SuperPower REBCO tapes is characterized using the "FBI" (force - field - current) superconductor test facility of the Institute for Technical Physics (ITEP) of the Karlsruhe Institute of Technology (KIT). In a first step, the magnetic background field is cycled while measuring the current carrying capabilities to determine the impact of Lorentz forces on the TSTC sample performance. In the first field cycle, the critical current of the TSTC sample is tested up to 12 T. A significant Lorentz force of up to 65.6 kN/m at the maximal magnetic background field of 12 T result in a 11.8 % irreversible degradation of the current carrying capabilities. The degradation saturates (critical cable current of 5.46 kA at 4.2 K and 12 T background field) and does not increase in following field cycles. In a second step, the sample is characterized at different background fields (4-12 T) and surface temperatures (4.2-37.8 K) utilizing the variable temperature insert of the "FBI" test facility. In a third step, the performance along the length of the sample is determined at 77 K, self-field. A 15 % degradation is obtained for the central part of the sample which was within the high field region of the magnet during the in-field measurements

Characterization of the association between bacterial ectosymbionts and Robbea sp. 2 nematodes from the Caribbean

Marine thiotrophe Symbiosen sind nicht nur in Lebensräumen wie der Tiefsee, in denen kein Sonnenlicht zur Energiegewinnung genutzt werden kann, von fundamentaler Bedeutung, sondern finden sich auch in seichten Gewässern. Marine Nematoden, die schwefeloxidierende bakterielle Symbionten auf ihrer Kutikula tragen (Stilbonematinae, Desmodoridae) kommen im Sand seichter Gewässer vor, in denen oxidierte O2 -reiche Schichten reduzierte H2S-reiche Schichten überlagern. Die Wanderung der Nematoden durch die Chemokline schafft gute Bedingungen für das Wachstum der angehefteten Symbionten, die den Nematoden als wichtigste Nahrungsquelle dienen. Aufgrund der Einfachheit dieser Assoziation haben sich Stilbonematinae für das Verständnis der Etablierung von Symbiose bereits als nützlich erwiesen. Trotzdem wurde bisher nur die Assoziation von Laxus oneistus beschrieben. Dort konnte gezeigt werden, dass der Symbiont einem einzigen Phylotyp der Klasse Gammaproteobakteria zugeordnet werden kann. In dieser Arbeit haben wir einen noch unbeschriebenen Stilbonematiden und dessen bakteriellen Symbionten von den Kaiman Inseln charakterisiert. Die Oberfläche des Wurms ist bedeckt von einer weissen, ein-schichtigen Lage von Kokken, die morphologisch einheitlich sind. 18S rDNA phylo-genetische Analysen zeigten, dass der Nematode zu den Stilbonematinae gehört. Da er aus morphologischer Sicht ein Mitglied der Gattung Robbea ist, haben wir die 18S rDNA mit zwei Vertretern dieses Genus verglichen. Wir konnten zeigen, dass sie-obwohl morphologisch eng verwandt-in der 18S rDNA Analyse nicht in eine ge-meinsame Gruppe fallen. Um die Diversität der Symbionten des Bakterienmantels zu bestimmen, haben wir auf PCR und FISH basierende Analysen durchgeführt und konnten zeigen dass nur ein Phylotyp an der Kutikula des Wurms existiert. In 16S rDNA Analysen gruppierten die Symbionten aller drei Robbea-Arten mit den schwefeloxidierenden Symbionten von Laxus oneistus und marinen darmlosen Oligochaeten. Das Vorhandensein und die Phylogenie des aprA Gens bei den Symbionten aller drei Robbea-Arten ist ein Hinweis, dass sie reduzierte Schwefelverbindungen als Energiequelle nutzen können. Schließlich konnten wir zum ersten Mal einen frei lebenden stilbonematinen Symbionten der Stilbonematinae in der Umwelt nachweisen.Thiotrophic symbiosis is of fundamental importance for life, not only in deep sea habitats, where no sunlight can be harnessed to generate energy, but also in shallow water environments. Free-living marine nematodes carrying sulfur-oxidizing bacterial symbionts on their cuticle (Stilbonematinae, Desmodoridae) occur in shallow water at the in-terface between O2-rich and hydrogen sulfid-rich sand layers. Migration of the nematodes through the chemocline favours the growth of the symbionts, which represent the nematodes’ major food source. Due to the relative simplicity of this association, stilbonematids have already proven to be useful for the understanding of symbiosis establishment. Nevertheless, only the Laxus oneistus association was analyzed so far and the bacterial symbiont found to belong to one single phylotype of Gammaproteobacteria. Here, we character-ized Robbea sp.2, a yet undescribed stilbonematid inhabiting a back-reef sand bar off Little Cayman (Cayman Islands). 18S rDNA-based phylogenetic analysis showed that the nematode belongs to the Stilbonematinae. Although morpho-logical analysis assigned it to the genus Robbea, this genus was not supported at the molecular level in our phylogenetic reconstruction. The surface of Rob-bea sp.2 is covered by a monolayer of morphologically undistinguishable white cocci. We performed PCR and FISH-based analysis and could show that only one phylotype is present on the worms’ cuticle. In a 16S rDNA-based tree, the symbionts of Robbea sp.2 could be placed in one cluster comprising the sulfur-oxidizing symbionts of L. oneistus and those of marine gutless oligochaetes. The presence and phylogeny of the aprA gene indicated that the symbionts can use reduced sulfur compounds as an energy source. Finally, we detected the 16S rDNA of the Robbea sp.2 symbionts not only in the vicinity of the worm´s habitat, but also in seawater collected far off the reef. This is the first report of the presence of a thiotrophic symbiont in off-shore surface seawater

Strengthening of the C-F Bond in Fumaryl Fluoride with Superacids

The reaction of fumaryl fluoride with the superacidic solutions XF/MF5 (X=H, D;M=As, Sb) results in the formation of the monoprotonated and diprotonated species, dependent on the stoichiometric ratio of the Lewis acid to fumaryl fluoride. The salts [C4H3F2O2](+)[MF6](-) (M=As, Sb) and [C4H2X2F2O2](2+)([MF6](-))(2) (X=H, D;M=As, Sb) are the first examples with a protonated acyl fluoride moiety. They were characterized by low-temperature vibrational spectroscopy. Low-temperature NMR spectroscopy and single-crystal X-ray structure analyses were carried out for [C4H3F2O2](+)[SbF6](-) as well as for [C4H4F2O2](2+)([MF6](-))(2) (M=As, Sb). The experimental results are discussed together with quantum chemical calculations of the cations [C4H4F2O2 . 2 HF](2+) and [C4H3F2O2 . HF](+) at the B3LYP/aug-cc-pVTZ level of theory. In addition, electrostatic potential (ESP) maps combined with natural population analysis (NPA) charges were calculated in order to investigate the electron distribution and the charge-related properties of the diprotonated species. The C-F bond lengths in the protonated dication are considerably reduced on account of the +R effect