Model independent analysis of nearly L\'evy correlations

A model-independent method for the analysis of the two-particle short-range correlations is presented, that can be utilized to describe e.g. Bose-Einstein (HBT), dynamical (ridge) or other correlation functions, that have a nearly L\'evy or streched exponential shape. For the special case of L\'evy exponent alpha = 1, the earlier Laguerre expansions are recovered, for the alpha = 2 special case, a new expansion method is obtained for nearly Gaussian correlation functions. Multi-dimensional L\'evy expansions are also introduced and their potential application to analyze rigde correlation data is discussed

Interaction-induced chiral p_x \pm i p_y superfluid order of bosons in an optical lattice

The study of superconductivity with unconventional order is complicated in condensed matter systems by their extensive complexity. Optical lattices with their exceptional precision and control allow one to emulate superfluidity avoiding many of the complications of condensed matter. A promising approach to realize unconventional superfluid order is to employ orbital degrees of freedom in higher Bloch bands. In recent work, indications were found that bosons condensed in the second band of an optical chequerboard lattice might exhibit p_x \pm i p_y order. Here we present experiments, which provide strong evidence for the emergence of p_x \pm i p_y order driven by the interaction in the local p-orbitals. We compare our observations with a multi-band Hubbard model and find excellent quantitative agreement

High-resolution measurements of atmospheric molecular hydrogen and its isotopic composition at the West African coast of Mauritania

Oceans are a net source of molecular hydrogen (H-2) to the atmosphere, where nitrogen (N-2) fixation is assumed to be the main biological production pathway followed by photochemical production from organic material. The sources can be distinguished using isotope measurements because of clearly differing isotopic signatures of the produced hydrogen. Here we present the first ship-borne measurements of atmospheric molecular H-2 mixing ratio and isotopic composition at the West African coast of Mauritania (16-25 degrees W, 17-24 degrees N). This area is one of the biologically most active regions of the world's oceans with seasonal upwelling events and characterized by strongly differing hydrographical/ biological properties and phytoplankton community structures. The aim of this study was to identify areas of H-2 production and distinguish H-2 sources by isotopic signatures of atmospheric H-2. For this more than 100 air samples were taken during two cruises in February 2007 and 2008. During both cruises a transect from the Cape Verde Islands towards the Mauritanian Coast was sampled to cover differing oceanic regions such as upwelling and oligotrophic regimes. In 2007, additionally, four days were sampled at high resolution of one sample per hour to investigate a possible diurnal cycle of atmospheric H-2. Our results indicate the influence of local sources and suggest the Banc d'Arguin as a pool for precursors for photochemical H-2 production, whereas oceanic N-2 fixation could not be identified as a source for atmospheric H-2 during these two cruises. The variability in diurnal cycles is probably influenced by released precursors for photochemical H-2 production and also affected by a varying origin of air masses. This means for future investigations that only measuring the mixing ratio of H-2 is insufficient to explain the variability of an atmospheric diurnal cycle and support is needed, e.g. by isotopic measurements. Nevertheless, measurements of atmospheric H-2 mixing ratios, which are easy to conduct online during ship cruises, could be a useful indicator of production areas of biological precursors such as volatile organic compounds (VOCs) for further investigations

Isotopic evidence for biogenic molecular hydrogen production in the Atlantic Ocean

Oceans are a net source of molecular hydrogen (H2) to the atmosphere. The production of marine H2 is assumed to be mainly biological by N2 fixation, but photochemical pathways are also discussed. We present measurements of mole fraction and isotopic composition of dissolved and atmospheric H2 from the southern and northern Atlantic between 2008 and 2010. In total almost 400 samples were taken during five cruises along a transect between Punta Arenas (Chile) and Bremerhaven (Germany), as well as at the coast of Mauretania. The isotopic source signatures of dissolved H2 extracted from surface water are highly deuterium-depleted and correlate negatively with temperature, showing δD values of (−629 ± 54) ‰ for water temperatures at (27 ± 3) °C and (−249 ± 88) ‰ below (19 ± 1) °C. The results for warmer water masses are consistent with biological production of H2. This is the first time that marine H2 excess has been directly attributed to biological production by isotope measurements. However, the isotope values obtained in the colder water masses indicate that beside possible biological production a significant different source should be considered. The atmospheric measurements show distinct differences between both hemispheres as well as between seasons. Results from the global chemistry transport model TM5 reproduce the measured H2 mole fractions and isotopic composition well. The climatological global oceanic emissions from the GEMS database are in line with our data and previously published flux calculations. The good agreement between measurements and model results demonstrates that both the magnitude and the isotopic signature of the main components of the marine H2 cycle are in general adequately represented in current atmospheric models despite a proposed source different from biological production or a substantial underestimation of nitrogen fixation by several authors

A high-altitude peatland record of environmental changes in the NW Argentine Andes (24 ° S) over the last 2100 years

High-altitude cushion peatlands are versatile archives for high-resolution palaeoenvironmental studies, due to their high accumulation rates, range of proxies, and sensitivity to climatic and/or human-induced changes. Especially within the Central Andes, the knowledge about climate conditions during the Holocene is limited. In this study, we present the environmental and climatic history for the last 2100 years of Cerro Tuzgle peatland (CTP), located in the dry Puna of NW Argentina, based on a multi-proxy approach. X-ray fluorescence (XRF), stable isotope and element content analyses (δ13C, δ15N, TN and TOC) were conducted to analyse the inorganic geochemistry throughout the sequence, revealing changes in the peatlands' past redox conditions. Pollen assemblages give an insight into substantial environmental changes on a regional scale. The palaeoclimate varied significantly during the last 2100 years. The results reflect prominent late Holocene climate anomalies and provide evidence that in situ moisture changes were coupled to the migration of the Intertropical Convergence Zone (ITCZ). A period of sustained dry conditions prevailed from around 150 BC to around AD 150. A more humid phase dominated between AD 200 and AD 550. Afterwards, the climate was characterised by changes between drier and wetter conditions, with droughts at around AD 650-800 and AD 1000-1100. Volcanic forcing at the beginning of the 19th century (1815 Tambora eruption) seems to have had an impact on climatic settings in the Central Andes. In the past, the peatland recovered from climatic perturbations. Today, CTP is heavily degraded by human interventions, and the peat deposit is becoming increasingly susceptible to erosion and incision.Fil: Schittek, Karsten. University of Heidelberg; Alemania. Universitat Zu Köln; AlemaniaFil: Kock, Sebastian T.. University of Heidelberg; Alemania. Research Center Jülich; AlemaniaFil: Lücke, Andreas. Helmholtz Gemeinschaft. Forschungszentrum Jülich; AlemaniaFil: Hense, Jonathan. Universitaet Bonn; AlemaniaFil: Ohlendorf, Christian. Universitat Bremen; AlemaniaFil: Kulemeyer, Julio José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Jujuy. Universidad Nacional de Jujuy. Centro de Investigaciones y Transferencia de Jujuy; ArgentinaFil: Lupo, Liliana Concepcion. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Jujuy. Universidad Nacional de Jujuy. Centro de Investigaciones y Transferencia de Jujuy; ArgentinaFil: Schäbitz, Frank. Universitat Zu Köln; Alemani

The “Open Innovation” paradigm: A contingency perspective

The “open innovation” model is currently being touted as a superior path for achieving long-term success. Rather than relying on their own, limited resources for research and development in the traditional, closed invention system, firms are encouraged to share knowledge across firm boundaries to enhance their innovative potential. Yet, such sharing may also have adverse consequences by reducing the rarity of a firm’s inventions. This paper accordingly attempts to identify and analyze the parameters that determine whether open or closed types of innovation management are most appropriate for a given firm. Following a contingency perspective, we examine these determinants as various internal and external constraints (situational factors). More specifically, applying concepts related to absorptive capacity, complementary resources, game theory and others, we derive testable propositions and provide case study evidence regarding the value generating properties of open innovation.Peer Reviewe

Toetsontwikkeling op virussen in Zantedeschia

Zantedeschia (=Calla) heeft zich ontwikkeld tot een belangrijk siergewas. Voor de productie van snijbloemen en potplanten is een goede kwaliteit vereist. Virus kan een sterk negatieve invloed hebben op de kwaliteit door o.a. groeimisvorming en kleurbreking op blad en bloem. Een kleine tien jaar geleden is de BKD op verzoek van het vak gestart met een keuring op o.a. zichtbaar virus. Sinds het groeiseizoen van 2003 zijn de virusproblemen ondanks de keuring alleen maar groter geworden. Het beperken van virusverspreiding in Zantedeschia is daarom recent in detail bestudeerd (PT-project 12048). Daarnaast is een goed toetsenpakket belangrijk om virusvrij uitgangsmateriaal te kunnen realiseren. Zonder robuuste toetsen op virussen in Zantedeschia is dit haast onmogelijk te verwezenlijken. Er zijn veel verschillende virussen gevonden in Zanedeschia en dit aantal is de afgelopen jaren verder gestegen. Een aantal virussen in Zanedeschia kan prima via serologische methoden als ELISA worden aangetoond; andere virussen alleen door middel van PCR. Voor sommige virussen in Zantedeschia waren bij de Bloembollenkeuringsdienst (BKD) en Praktijkonderzoek Plant en Omgeving (PPO-BBF) geen goede detectiemethoden aanwezig, of was bekend dat ze slecht met de bestaande toetsmethoden te detecteren zijn. Dit was een onbevredigende situatie, met name voor bedrijven die schoon uitgangsmateriaal willen uitleveren. Daarom heeft dit project als belangrijkste doel de kennis over virussen in Zantedeschia te vergroten en het pakket aan toetsmogelijkheden compleet te maken. De ELISA- en PCR-toetsen zijn binnen dit project gevalideerd met praktijkmateriaal en het protocol voor het toetsen op uitgangsmateriaal is geëvalueerd