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Interaction between the Hypothalamic-Pituitary-Adrenal Axis and the Circadian Clock System in Humans
(2017)
Rotation of the Earth creates day and night cycles of 24 h. The endogenous circadian clocks sense these light/dark rhythms and the master pacemaker situated in the suprachiasmatic nucleus of the hypothalamus entrains the physical activities according to this information. The circadian machinery is built from the transcriptional/translational feedback loops generating the oscillations in all nucleated cells of the body. In addition, unexpected environmental changes, called stressors, also challenge living systems. A response to these stimuli is provided immediately via the autonomic-nervous system and slowly via the hypothalamus"pituitary"adrenal (HPA) axis. When the HPA axis is activated, circulating glucocorticoids are elevated and regulate organ activities in order to maintain survival of the organism. Both the clock and the stress systems are essential for continuity and interact with each other to keep internal homeostasis. The physiological interactions between the HPA axis and the circadian clock system are mainly addressed in animal studies, which focus on the effects of stress and circadian disturbances on cardiovascular, psychiatric and metabolic disorders. Although these studies give opportunity to test in whole body, apply unwelcome techniques, control and manipulate the parameters at the high level, generalization of the results to humans is still a debate. On the other hand, studies established with cell lines cannot really reflect the conditions occurring in a living organism. Thus, human studies are absolutely necessary to investigate mechanisms involved in stress and circadian responses. The studies presented in this thesis were intended to determine the effects of cortisol as an end-product of the HPA axis on PERIOD (PER1, PER2 and PER3) transcripts as circadian clock genes in healthy humans. The expression levels of PERIOD genes were measured under baseline conditions and after stress in whole blood. The results demonstrated here have given better understanding of transcriptional programming regulated by pulsatile cortisol at standard conditions and short-term effects of cortisol increase on circadian clocks after acute stress. These findings also draw attention to inter-individual variations in stress response as well as non-circadian functions of PERIOD genes in the periphery, which need to be examined in details in the future.
Diese Arbeit konzentriert sich auf die Darstellung gemeinsamer Projekte von Hotelunternehmen und Hochschulen mit hotelspezifischen Studienangeboten. Infolge der demografischen Entwicklungen sowie des Wertewandels gewinnen Personalgewinnung und Mitarbeiterloyalisierung zunehmend an Bedeutung und werden zu einem Wettbewerbsparameter der Hotellerie. Für diese essentielle Herausforderung sind Hotelbetriebe mit engagierter Mitarbeiterförderung gefragt. Viele Hochschulen haben neue Studiengänge im Tourismus, Event- oder Hotelmanagementbereich praxisorientiert aufgelegt, um der Skepsis der Hotellerie entgegen zu wirken und um zugleich den Erwartungen der Studenten gerecht zu werden. Viele der Studenten wären potenzielle Auszubildende, die sich bei der Abwägung allerdings für die Studienoption entschieden haben. Daher ist es wichtig, in enger Kooperation mit den hierzu passenden Institutionen und Bildungsträgern, vor allem praxisnahe Studienmodelle für sich verändernde Erwartungen der Bewerber mit modernen Lehrinhalten zu entwickeln und erfolgreich am Markt zu platzieren. Daher verfolgt diese Arbeit den Ansatz, adäquate Kriterien und Faktoren für den Erfolg vertraglich vereinbarter Kooperationen zwischen Hotelketten und Hochschulen zu analysieren und daraus Handlungsempfehlungen abzuleiten. Die große Anzahl an Kooperationen macht deutlich, dass die Notwendigkeit für die Hotellerie, sich im Bereich der Mitarbeitergewinnung, -bindung und -entwicklung mit akademischen Partnern zusammen zu schließen, bei einer ansteigenden Zahl von Hotelgruppen nachvollzogen wird. Durch die zurückhaltende Vermarktung vieler Kooperationsmodelle ist deren Bekanntheit jedoch begrenzt und dadurch auch deren positive Auswirkungen auf das Image der Hotellerie. Gleichwohl sind in der Bildungslandschaft steigende Studentenzahlen und eine Vermehrung der Studiengänge bei gleichzeitig gravierender Abnahme der Zahl berufsfachlich Ausgebildeter erkennbar. Die Kooperationsmodelle sind daher ein sinnvolles Instrument, um auf diese Marktentwicklungen zu reagieren, wobei ihre Bedeutung primär von Unternehmen mit strategischer Personalpolitik erkannt wird. Daraus wurde die "Typologie privilegierter Bildungspartnerschaften" mit einer Bandbreite von zehn Kooperationstypen entwickelt. Damit werden unterschiedliche Intensitäten der partnerschaftlichen Bildungselemente ebenso deutlich wie ein individualisiertes "Faktoren-Phasenmodell", dass die Prozessstruktur der Kooperationsentwicklung abbildet. Je nach Enge der Zusammenarbeit, nach Unternehmens- und Hochschulphilosophie und entsprechend der Erfahrungen mit Kooperationen entstehen vor allem Verpflichtungen und Herausforderungen in der aktiven Gestaltung und verlässlichen Kommunikation in einem Kooperationsmodell. Eine Schlüsselrolle nimmt der persönlich verantwortliche Koordinator ein, der als Garant für eine effiziente Organisation und Professionalität angesehen wird. Daraus ableitend sind die Erfolgsfaktoren im ASP-Modell herausgefiltert worden: Attraktivität, Sicherheit und Persönlichkeit machen den Erfolg einer privilegierten Bildungspartnerschaft aus. Bestätigt wurde zudem, dass die Erfahrung der beiden Partner einer Kooperation zueinander passen muss und eine klare Zielvereinbarung mit Fixierung der Pflichten und Aufgaben erforderlich ist. Ein hoher Qualitätsanspruch, Transparenz und Prozesseffizienz ergänzen dies und machen deutlich, dass der Bildungsbereich als Teil der Personalpolitik eines Unternehmens sensibel und anspruchsvoll zugleich ist. Die Verankerung auf der Führungsebene eines Unternehmens ist entscheidend, um durch ein Signal nach innen und außen den Stellenwert einer Bildungsallianz zu verdeutlichen. Wenn aus Lernen und Wissen wirtschaftliche Vorteile erarbeitet werden können, wird Bildung noch mehr als Markenkern eines guten Arbeitgebers interpretiert. Auf dieser Grundlage wird der Gedanke der Personalentwicklung durch den Ansatz fortwährender Mitarbeiterbildung perfektioniert und der Lösungsansatz einer "privilegierten Bildungspartnerschaft" legt den Grundstein dafür. Nachwuchskräfteförderung wird zum strategischen Mittel der Mitarbeiterbindung und zur Vermeidung kostenintensiver Vakanzen, zudem sichern Netzwerke Fachwissen und stärken das Unternehmensimage. Mit privilegierten Bildungspartnerschaften werden geeignete Modelle vorgestellt, um einsatzfreudige Mitarbeiter zu halten und sie gleichzeitig auf den nächsten Karriereschritt vorzubereiten. Die vorliegende Ausarbeitung liefert einen Diskussionsbeitrag zum besseren gegenseitigen Verständnis einer Symbiose aus Hotelkette und Hochschule im Bildungsbereich sowie erfolgreiche Konzeptideen für vielfältige Netzwerkstrukturen.
Digital libraries have become a central aspect of our live. They provide us with an immediate access to an amount of data which has been unthinkable in the past. Support of computers and the ability to aggregate data from different libraries enables small projects to maintain large digital collections on various topics. A central aspect of digital libraries is the metadata -- the information that describes the objects in the collection. Metadata are digital and can be processed and studied automatically. In recent years, several studies considered different aspects of metadata. Many studies focus on finding defects in the data. Specifically, locating errors related to the handling of personal names has drawn attention. In most cases the studies concentrate on the most recent metadata of a collection. For example, they look for errors in the collection at day X. This is a reasonable approach for many applications. However, to answer questions such as when the errors were added to the collection we need to consider the history of the metadata itself. In this work, we study how the history of metadata can be used to improve the understanding of a digital library. To this goal, we consider how digital libraries handle and store their metadata. Based in this information we develop a taxonomy to describe available historical data which means data on how the metadata records changed over time. We develop a system that identifies changes to metadata over time and groups them in semantically related blocks. We found that historical meta data is often unavailable. However, we were able to apply our system on a set of large real-world collections. A central part of this work is the identification and analysis of changes to metadata which corrected a defect in the collection. These corrections are the accumulated effort to ensure data quality of a digital library. In this work, we present a system that automatically extracts corrections of defects from the set of all modifications. We present test collections containing more than 100,000 test cases which we created by extracting defects and their corrections from DBLP. This collections can be used to evaluate automatic approaches for error detection. Furthermore, we use these collections to study properties of defects. We will concentrate on defects related to the person name problem. We show that many defects occur in situations where very little context information is available. This has major implications for automatic defect detection. We also show that properties of defects depend on the digital library in which they occur. We also discuss briefly how corrected defects can be used to detect hidden or future defects. Besides the study of defects, we show that historical metadata can be used to study the development of a digital library over time. In this work, we present different studies as example how historical metadata can be used. At first we describe the development of the DBLP collection over a period of 15 years. Specifically, we study how the coverage of different computer science sub fields changed over time. We show that DBLP evolved from a specialized project to a collection that encompasses most parts of computer science. In another study we analyze the impact of user emails to defect corrections in DBLP. We show that these emails trigger a significant amount of error corrections. Based on these data we can draw conclusions on why users report a defective entry in DBLP.
Nos recherches ont exploré l’espace transculturel dans la dramaturgie québécoise contemporaine. Notre travail a été principalement basé sur le concept de transgressivité de Bertrand Westphal [WESTPHAL : 2007] et la notion de transculturalité proposée par Wolfgang Welsch [WELSCH : 1999].
La réflexion menée par Welsch nous a inspiré dans l’établissement des trois grands axes de notre analyse, autour desquels se sont articulées les dimensions transculturelles superposées : l’axe syncrétique, l’axe intime et l’axe cosmopolite. Ces axes ont déterminé le choix de notre corpus, provenant de l’époque transculturelle du Québec entre 1975 et 1995. L’axe syncrétique s’est dessiné à partir de la présence de cultures modernes interconnectées, où les façons de vivre ne se limitent pas aux frontières culturelles nationales. Elles les « transgressent » et se retrouvent dans d’autres cultures. L’axe intime découle de ce que les individus – le(s) Moi(s) – sont des hybrides culturels, chaque individu se formant par des attachements multiples. Ils interagissent entre eux, créant ainsi une transculturalité interne. L’axe cosmopolite renferme une dimension qui représente de nombreuses façons de vivre et diverses vies culturelles qui s’interpénètrent mutuellement. Elles interagissent entre elles, mais aussi avec des espaces considérés comme étant hors du contexte transculturel.
Nous avons tenu à développer notre projet autour des prémisses théoriques de la géocritique. Cela nous a conduit à établir une grille d’analyse spécifique afin de découvrir le mode de fonctionnement de l’espace humain transculturel. L’analyse s’est basée uniquement sur le texte dramatique. Des dispositifs inspirés de la géocritique ont dévoilé quelques caractéristiques primordiales des dimensions transculturelles superposées de la diversité québécoise.
Die Arbeit untersucht den Zusammenhang zwischen dem sprachlichen Zeichen und den Begriffen. Das Lexikon mit seinen Bedeutungsdefinitionen ist der augenscheinlichste Schnittpunkt zwischen dem Sprach- und dem Begriffssystem. Die Bedeutungsdefinition wird dabei als ein empirisches Datum betrachtet, das formal beschrieben werden kann. Die Bedeutungsanalyse überführt die Bedeutungsdefinition in eine komplexe Ordnungsstruktur. Die Methode wurde aus verschiedenen Begriffstheorien entwickelt, hauptsächlich aus Raili Kauppis Begriffstheorie und der Formalen Begriffsanalyse. Im Ergebnis erhält man aus den Bedeutungen eines Lexikons ein komplexes System von ein- bis n-stelligen Begriffen. Dieses Begriffssystem unterscheidet sich von den bekannten Semantischen Netzen durch einen völligen Verzicht auf von außen auf das System projizierte Relationen, wie den sogenannten semantischen Relationen. Die einzigen Relationen in diesem System sind begrifflich.
Global human population growth is associated with many problems, such asrnfood and water provision, political conflicts, spread of diseases, and environmental destruction. The mitigation of these problems is mirrored in several global conventions and programs, some of which, however, are conflicting. Here, we discuss the conflicts between biodiversity conservation and disease eradication. Numerous health programs aim at eradicating pathogens, and many focus on the eradication of vectors, such as mosquitos or other parasites. As a case study, we focus on the "Pan African Tsetse and Trypanosomiasis Eradication Campaign," which aims at eradicating a pathogen (Trypanosoma) as well as its vector, the entire group of tsetse flies (Glossinidae). As the distribution of tsetse flies largely overlaps with the African hotspots of freshwater biodiversity, we argue for a strong consideration of environmental issues when applying vector control measures, especially the aerial applications of insecticides.rnFurthermore, we want to stimulate discussions on the value of speciesrnand whether full eradication of a pathogen or vector is justified at all. Finally, we call for a stronger harmonization of international conventions. Proper environmental impact assessments need to be conducted before control or eradication programs are carried out to minimize negative effects on biodiversity.
Flexibility and spatial mobility of labour are central characteristics of modern societies which contribute not only to higher overall economic growth but also to a reduction of interregional employment disparities. For these reasons, there is the political will in many countries to expand labour market areas, resulting especially in an overall increase in commuting. The picture of the various, unintended long-term consequences of commuting on individuals is, however, relatively unclear. Therefore, in recent years, the journey to work has gained high attention especially in the study of health and well-being. Empirical analyses based on longitudinal as well as European data on how commuting may affect health and well-being are nevertheless rare. The principle aim of this thesis is, thus, to address this question with regard to Germany using data from the Socio-Economic Panel. Chapter 2 empirically investigates the causal impact of commuting on absence from work due to sickness-related reasons. Whereas an exogenous change in commuting distance does not affect the number of absence days of those individuals who commute short distances to work, it increases the number of absence days of those employees who commute middle (25 " 49 kilometres) or long distances (50 kilometres and more). Moreover, our results highlight that commuting may deteriorate an individual- health. However, this effect is not sufficient to explain the observed impact of commuting on absence from work. Chapter 3 explores the relationship between commuting distance and height-adjusted weight and sheds some light on the mechanisms through which commuting might affect individual body weight. We find no evidence that commuting leads to excess weight. Compensating health behaviour of commuters, especially healthy dietary habits, could explain the non-relationship of commuting and height-adjusted weight. In Chapter 4, a multivariate probit approach is used to estimate recursive systems of equations for commuting and health-related behaviours. Controlling for potential endogeneity of commuting, the results show that long distance commutes significantly decrease the propensity to engage in health-related activities. Furthermore, unobservable individual heterogeneity can influence both the decision to commute and healthy lifestyle choices. Chapter 5 investigates the relationship between commuting and several cognitive and affective components of subjective well-being. The results suggest that commuting is related to lower levels of satisfaction with family life and leisure time which can largely be ascribed to changes in daily time use patterns, influenced by the work commute.
Long-Term Memory Updating: The Reset-of-Encoding Hypothesis in List-Method Directed Forgetting
(2017)
People- memory for new information can be enhanced by cuing them to forget older information, as is shown in list-method directed forgetting (LMDF). In this task, people are cued to forget a previously studied list of items (list 1) and to learn a new list of items (list 2) instead. Such cuing typically enhances memory for the list 2 items and reduces memory for the list 1 items, which reflects effective long-term memory updating. This review focuses on the reset-of-encoding (ROE) hypothesis as a theoretical explanation of the list 2 enhancement effect in LMDF. The ROE hypothesis is based on the finding that encoding efficacy typically decreases with number of encoded items and assumes that providing a forget cue after study of some items (e.g., list 1) resets the encoding process and makes encoding of subsequent items (e.g., early list 2 items) as effective as encoding of previously studied (e.g., early list 1) items. The review provides an overview of current evidence for the ROE hypothesis. The evidence arose from recent behavioral, neuroscientific, and modeling studies that examined LMDF on both an item and a list level basis. The findings support the view that ROE plays a critical role for the list 2 enhancement effect in LMDF. Alternative explanations of the effect and the generalizability of ROE to other experimental tasks are discussed.
Monetary Policy During Times of Crisis - Frictions and Non-Linearities in the Transmission Mechanism
(2017)
For a long time it was believed that monetary policy would be able to maintain price stability and foster economic growth during all phases of the business cycle. The era of the Great Moderation, often also called the Volcker-Greenspan period, beginning in the mid 1980s was characterized by a decline in volatility of output growth and inflation among the industrialized countries. The term itself is first used by Stock and Watson (2003). Economist have long studied what triggered the decline in volatility and pointed out several main factors. An important research strand points out structural changes in the economy, such as a decline of volatility in the goods producing sector through better inventory controls and developments in the financial sector and government spending (McConnell2000, Blanchard2001, Stock2003, Kim2004, Davis2008). While many believed that monetary policy was only 'lucky' in terms of their reaction towards inflation and exogenous shocks (Stock2003, Primiceri2005, Sims2006, Gambetti2008), others reveal a more complex picture of the story. Rule based monetary policy (Taylor1993) that incorporates inflation targeting (Svensson1999) has been identified as a major source of inflation stabilization by increasing transparency (Clarida2000, Davis2008, Benati2009, Coibion2011). Apart from that, the mechanics of monetary policy transmission have changed. Giannone et al. (2008) compare the pre-Great Moderation era with the Great Modertation and find that the economies reaction towards monetary shocks has decreased. This finding is supported by Boivin et al. (2011). Similar to this, Herrera and Pesavento (2009) show that monetary policy during the Volcker-Greenspan period was very effective in dampening the effects of exogenous oil price shocks on the economy, while this cannot be found for the period thereafter. Yet, the subprime crisis unexpectedly hit worldwide economies and ended the era of Great Moderation. Financial deregulation and innovation has given banks opportunities for excessive risk taking, weakened financial stability (Crotty2009, Calomiris2009) and led to the build-up of credit-driven asset price bubbles (SchularickTaylor2012). The Federal Reserve (FED), that was thought to be the omnipotent conductor of price stability and economic growth during the Great Moderation, failed at preventing a harsh crisis. Even more, it did intensify the bubble with low interest rates following the Dotcom crisis of the early 2000s and misjudged the impact of its interventions (Taylor2009, Obstfeld2009). New results give a more detailed explanation on the question of latitude for monetary policy raised by Bernanke and suggest the existence of non-linearities in the transmission of monetary policy. Weise (1999), Garcia and Schaller (2002), Lo and Piger (2005), Mishkin (2009), Neuenkirch (2013) and Jannsen et al. (2015) find that monetary policy is more potent during times of financial distress and recessions. Its effectiveness during 'normal times' is much weaker or even insignificant. This prompts the question if these non-linearities limit central banks ability to lean against bubbles and financial imbalances (White2009, Walsh2009, Boivin2010, Mishkin2011).
In recent decades, the Arctic has been undergoing a wide range of fast environmental changes. The sea ice covering the Arctic Ocean not only reacts rapidly to these changes, but also influences and alters the physical properties of the atmospheric boundary layer and the underlying ocean on various scales. In that regard, polynyas, i.e. regions of open water and thin ice within thernclosed pack ice, play a key role as being regions of enhanced atmosphere-ice-ocean interactions and extensive new ice formation during winter. A precise long-term monitoring and increased efforts to employ long-term and high-resolution satellite data is therefore of high interest for the polar scientific community. The retrieval of thin-ice thickness (TIT) fields from thermal infrared satellite data and atmospheric reanalysis, utilizing a one-dimensional energy balance model, allows for the estimation of the heat loss to the atmosphere and hence, ice-production rates. However, an extended application of this approach is inherently connected with severe challenges that originate predominantly from the disturbing influence of clouds and necessary simplifications in the model set-up, which all need to be carefully considered and compensated for. The presented thesis addresses these challenges and demonstrates the applicability of thermal infrared TIT distributions for a long-term polynya monitoring, as well as an accurate estimation of ice production in Arctic polynyas at a relatively high spatial resolution. Being written in a cumulative style, the thesis is subdivided into three parts that show the consequent evolution and improvement of the TIT retrieval, based on two regional studies (Storfjorden and North Water (NOW) polynya) and a final large-scale, pan-Arctic study. The first study on the Storfjorden polynya, situated in the Svalbard archipelago, represents the first long-term investigation on spatial and temporal polynya characteristics that is solely based on daily TIT fields derived from MODIS thermal infrared satellite data and ECMWF ERA-Interim atmospheric reanalysis data. Typical quantities such as polynya area (POLA), the TIT distribution, frequencies of polynya events as well as the total ice production are derived and compared to previous remote sensing and modeling studies. The study includes a first basic approach that aims for a compensation of cloud-induced gaps in daily TIT composites. This coverage-correction (CC) is a mathematically simple upscaling procedure that depends solely on the daily percentage of available MODIS coverage and yields daily POLA with an error-margin of 5 to 6 %. The NOW polynya in northern Baffin Bay is the main focus region of the second study, which follows two main goals. First, a new statistics-based cloud interpolation scheme (Spatial Feature Reconstruction - SFR) as well as additional cloud-screening procedures are successfully adapted and implemented in the TIT retrieval for usage in Arctic polynya regions. For a 13-yr period, results on polynya characteristics are compared to the CC approach. Furthermore, an investigation on highly variable ice-bridge dynamics in Nares Strait is presented. Second, an analysis of decadal changes of the NOW polynya is carried out, as the additional use of a suite of passive microwave sensors leads to an extended record of 37 consecutive winter seasons, thereby enabling detailed inter-sensor comparisons. In the final study, the SFR-interpolated daily TIT composites are used to infer spatial and temporal characteristics of 17 circumpolar polynya regions in the Arctic for 2002/2003 to 2014/2015. All polynya regions combined cover an average thin-ice area of 226.6 -± 36.1 x 10-³ km-² during winter (November to March) and yield an average total wintertime accumulated ice production of about 1811 -± 293 km-³. Regional differences in derived ice production trends are noticeable. The Laptev Sea on the Siberian shelf is presented as a focus region, as frequently appearing polynyas along the fast-ice edge promote high rates of new ice production. New affirming results on a distinct relation to sea-ice area export rates and hence, the Transpolar Drift, are shown. This new high-resolution pan-Arctic data set can be further utilized and build upon in a variety of atmospheric and oceanographic applications, while still offering room for further improvements such as incorporating high-resolution atmospheric data sets and an optimized lead-detection.