43 research outputs found
Optimum currency area theory: A selective review
No full textThe first part of this paper is a review of significant papers in the vast literature on optimum currency area (OCA) theory. The author focuses on the main classical contributions, then considers modern treatment of OCA theory. The second part considers empirical literature on the types of geographical areas that might constitute optimum currency areas, particularly with respect to asymmetry and symmetry of shocks.
Optimum currency area theory: A selective review
No full textThe first part of this paper is a review of significant papers in the vast literature on optimum currency area (OCA) theory. The author focuses on the main classical contributions, then considers modern treatment of OCA theory. The second part considers empirical literature on the types of geographical areas that might constitute optimum currency areas, particularly with respect to asymmetry and symmetry of shocks.
Intakte Membranlipide als Indikator für mikrobielles Leben in der marinen tiefen Biosphäre
No full textThe main objective of this thesis was to elucidate the structure and carbon metabolism of microbial communities living in deeply buried sediments by using intact polar lipids (IPL) as markers for active microbial cells. A globally distributed sample set obtained during ODP Legs 201, 204, and 207, IODP Expeditions 301 and 311, and cruises Sonne SO147, Karei KY04-11, and Professor Logatchev TTR15 was analyzed to constrain the composition and quantity of deep marine subseafloor life on a global scale. Surface sediments contained abundant bacterial phospholipids having phosphatidylethanolamine, phosphatidylglycerol, and phosphatidylcholine as head groups with C16 and C18 acyl side chains, whereas the deeper sediment layers were dominated by archaeal glycolipids of tetraether and diether type with diglycosidic head groups. The transition from bacterial to archaeal lipids occurred within the top 0.1 mbsf of the sediment column. These results contrast previous studies based on microbiological methods which have identified a dominance of viable bacteria in deeply buried sediments. Supporting evidence comes from (i) "traditional- analysis of phospholipidderived fatty acids which confirmed the low contribution of bacteria to the total population, and (ii) improved microbiological methods which detected a higher proportion of archaeal cells compared to previous studies that possibly discriminated against archaeal phylogenetic lineages. Furthermore a decrease in IPL concentrations with depth was observed, following a similar relationship as previously seen for directly counted cells. IPL concentration was found to be dependent on concentration of sedimentary organic carbon, reflecting the inherent heterotrophic nature of this ecosystem. Modeling of organic carbon concentrations allowed to estimate the magnitude of the deep biosphere as 90 Pg of cellular C-units. This estimate is independent of microscopic cell counts and underlines the global importance of the deep biosphere. Carbon isotopic analysis indicated that the majority of the archaeal biomass is indeed heterotrophic and utilizes carbon derived from degradation of sedimentary organic matter to synthesize biomass. It could also be shown that methane oxidation in deeply buried sulfate-methane transition zones is mediated differently compared to seep-sites in surface sediments. Calculation of community turnover rates supported previous values on the order of hundreds to thousands of years. Such low rates point to maintenance energy requirements much lower than known from laboratory cultures and challenge our understanding of life
Intact membrane lipids as tracers for microbial life in the marine deep biosphere
No full textThe main objective of this thesis was to elucidate the structure and carbon metabolism of microbial communities living in deeply buried sediments by using intact polar lipids (IPL) as markers for active microbial cells. A globally distributed sample set obtained during ODP Legs 201, 204, and 207, IODP Expeditions 301 and 311, and cruises Sonne SO147, Karei KY04-11, and Professor Logatchev TTR15 was analyzed to constrain the composition and quantity of deep marine subseafloor life on a global scale. Surface sediments contained abundant bacterial phospholipids having phosphatidylethanolamine, phosphatidylglycerol, and phosphatidylcholine as head groups with C16 and C18 acyl side chains, whereas the deeper sediment layers were dominated by archaeal glycolipids of tetraether and diether type with diglycosidic head groups. The transition from bacterial to archaeal lipids occurred within the top 0.1 mbsf of the sediment column. These results contrast previous studies based on microbiological methods which have identified a dominance of viable bacteria in deeply buried sediments. Supporting evidence comes from (i) traditional- analysis of phospholipidderived fatty acids which confirmed the low contribution of bacteria to the total population, and (ii) improved microbiological methods which detected a higher proportion of archaeal cells compared to previous studies that possibly discriminated against archaeal phylogenetic lineages. Furthermore a decrease in IPL concentrations with depth was observed, following a similar relationship as previously seen for directly counted cells. IPL concentration was found to be dependent on concentration of sedimentary organic carbon, reflecting the inherent heterotrophic nature of this ecosystem. Modeling of organic carbon concentrations allowed to estimate the magnitude of the deep biosphere as 90 Pg of cellular C-units. This estimate is independent of microscopic cell counts and underlines the global importance of the deep biosphere. Carbon isotopic analysis indicated that the majority of the archaeal biomass is indeed heterotrophic and utilizes carbon derived from degradation of sedimentary organic matter to synthesize biomass. It could also be shown that methane oxidation in deeply buried sulfate-methane transition zones is mediated differently compared to seep-sites in surface sediments. Calculation of community turnover rates supported previous values on the order of hundreds to thousands of years. Such low rates point to maintenance energy requirements much lower than known from laboratory cultures and challenge our understanding of life
Essays in applied microeconomics on human behavior in teams and on online advertising
No full textIn the dynamic landscape of economic decision-making, human behavior often deviates from the rational, utility-maximizing model due to cognitive biases, emotional factors, social norms, and peer influence. In this dissertation, I explore these behavioral aspects through three key dimensions: Cognitive biases, social norms, and peer influence, and their profound implications for organizational structures and digital marketing strategies. In the first part, my co-author and I examine how peer effects influence team collaboration and productivity in an academic setting. In the second part, I analyze the interaction of monetary incentives and social dynamics in team settings. In part three, my co-authors and I study the impact of online advertising on user behavior and decision-making, revealing insights into the effectiveness of targeted marketing strategies. Through these studies, I highlight the necessity of incorporating behavioral insights into policy design, business strategies, and marketing practices to enhance efficiency and long-term productivity
SIGNIFICANT PERSONALITIES AS TURNING POINTS IN THE LIFE AND MUSIC OF JOHANNES BRAHMS
No full textThis paper aims to reveal the turning points in the life and work of German composer Johannes Brahms. These main events were influenced by certain figures of the epoch, whose encounters marked the artistic activity of Brahms. In explaining the reasons that lay behind the composition of a work, emotion is one of the most specific criteria. Personal experience becomes the indispensable condition of artistic creation and lays at the core of the creative impulse. The paper is structured according to the following four aspects: the first friends (together with Albert Dietrich and their mentor, Robert Schumann, Brahms contributed to the composition of the FAE Sonata for piano and violin, Julius Otto Grimm is the witness of Brahms’ love for Agathe von Siebold, while Julius Stockhausen emerges as the master of the Brahms lieder), the conductors who became the composer’s close friends and promoted his symphonies (Hermann Levi, Hans Richter, Hans von Bülow, the latter a genuine emissary of Brahms’s works, the author of the Three B syntagm – Bach, Beethoven, Brahms), the Viennese friends (the critic Eduard Hanslick, who characterized the works in Opp. 117-119 as genuine monologues and Joseph Hellmesberger, founder of the quartet name after him, with whom Brahms performed gems of the chamber music repertoire), and the confidants of Brahms, permanent figures in the life of the composer (the surgeon Theodor Billroth and Joseph Viktor Widmann, the author of the memoirs that revealed significant aspects of the composer’s life and works).
REZUMAT. RECONSTITUIREA IDENTITĂȚII BRAHMSIENE – PERSONALITĂȚI MARCANTE ÎN VIAȚA ȘI OPERA LUI BRAHMS. Prezentul articol face referire la principalele evenimente din viața și creația lui Johannes Brahms prin prezentarea personalităților care i-au marcat activitatea artistică. Criteriul definitoriu în alegerea motivelor unei opere este acela al emoției personale, experiența proprie devine condiție indispensabilă a creației artistice și stă la baza impulsului creator. Articolul vizează patru aspecte: Primii prieteni: împreună cu Albert Dietrich și cu al lor mentor, Robert Schumann, creează Sonata FAE pentru pian și vioară, Julius Otto Grimm, martorul iubirii pentru Agathe von Siebold și maestrul liedurilor brahmsiene, Julius Stockhausen. Se vor afirma prietenii dirijori, promotori ai erei simfonice brahmsiene: Hermann Levi, Hans Richter, Hans von Bülow – un adevărat emisar al creației brahmsiene, autorul sintagmei celor 3 B-uri (Bach, Beethoven, Brahms). Al treilea aspect prezintă prietenii vienezi, criticul Eduard Hanslick, cel care caracterizează opusurile 117-119 drept veritabile monologuri, Joseph Hellmesberger conducătorul renumitului cvartet cu același nume, cu care a interpretat bijuterii muzicale camerale. În final se conturează personalitățile celor doi confesatori, prezențe permanente în viața lui Brahms: chirurgul Theodor Billroth și Joseph Viktor Widmann, cel din urmă fiind autorul memoriilor care au scos la lumină multe aspecte revelatoare ale vieții și creației compozitorului.
Cuvinte cheie: viața și creația brahmsiană, personalități marcante, prieten
In situ shear behavior of open-cell austenitic 316L steel foams
No full textKaya, Ali Can/0000-0003-2856-5508WOS:000566397000007Foam cores in crash boxes are subjected to large shear forces during crash situations. Here, the failure behavior of 316L open-cell stainless steel foams under shearing conditions was investigated. A custom-made grip system was used to conduct in situ experiments with a scanning electron microscope and a digital light microscope. A foam model was created based on mu-CT data and imported into FE software for simulation of the shearing test. Furthermore, the shear-induced strain fields were evaluated using digital image correlation. On the mesoscale, the foam cells mainly experienced torsion, while on the microscale, the foam struts failed due to tensile and bending loading. Twisted cells became almost parallel to the loading direction, leading to the tensile loading of the foam struts. Many slip lines developed on the strut walls, revealing that the steel struts underwent ductile fracture. In conclusion, the failure behavior of the foam struts and cells was greatly influenced by the loading conditions of the foams.Turkish Ministry of EducationTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [1416]The author gratefully acknowledges Prof. Claudia Fleck (Materials Engineering, TU Berlin) for her great support, help, valuable discussions, and permitting the use of the FE Software (Abaqus 6.12-2, Dassault Syst.emes Simulia Corp., Providence, RI, USA). The author further thanks the Julius Wolff Institute, Charit.e Universitatsmedizin Berlin, for use of the DANTEC Istra DIC system. The author acknowledges generous support of Dr. Paul Zaslansky (Charit.e Universitatsmedizin Berlin, Zentrum fur Zahn-, Mund-, und Kieferheilkunde, Berlin) during measurement process with DANTEC Istra DIC system. Ali Can Kaya thanks the Turkish Ministry of Education for a doctoral grant [Grant No. 1416]. The mu -CT data used for the FE simulations were obtained thanks to the generous support of Dr. Sebastian F. Fischer (RWTH Aachen, Foundry Institute), who is gratefully acknowledged
Microbial communities in methane- and short chain alkane-rich hydrothermal sediments of Guaymas Basin
No full textThe hydrothermal sediments of Guaymas Basin, an active spreading center in the Gulf of California (Mexico), are rich in porewater methane, short-chain alkanes, sulfate and sulfide, and provide a model system to explore habitat preferences of microorganisms, including sulfate-dependent, methane- and short chain alkane-oxidizing microbial communities. In this study, sediments (above 60˚C) covered with sulfur-oxidizing microbial mats surrounding a hydrothermal mound (termed Mat Mound) were characterized by porewater geochemistry of methane, C2-C6 short-chain alkanes, sulfate, sulfide, sulfate reduction rate measurements, in-situ temperature gradients, bacterial and archaeal 16S rRNA gene clone libraries and V6 tag pyrosequencing. The most abundantly detected groups in the Mat mound sediments include anaerobic methane-oxidizing archaea of the ANME-1 lineage and its sister clade ANME-1Guaymas, the uncultured bacterial groups SEEP-SRB2 within the Deltaproteobacteria and the separately branching HotSeep-1 Group; these uncultured bacteria are candidates for sulfate-reducing alkane oxidation and for sulfate-reducing syntrophy with ANME archaea. The archaeal dataset indicates distinct habitat preferences for ANME-1, ANME-1-Guaymas and ANME-2 archaea in Guaymas Basin hydrothermal sediments. The bacterial groups SEEP-SRB2 and HotSeep-1 co-occur with ANME-1 and ANME-1Guaymas in hydrothermally active sediments underneath microbial mats in Guaymas Basin. We propose the working hypothesis that this mixed bacterial and archaeal community catalyzes the oxidation of both methane and short-chain alkanes, and constitutes a microbial community signature that is characteristic for hydrothermal and/or cold seep sediments containing both substrates
