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Zeit und Antike
(1926)
Thema der vorliegenden Studie ist die Evaluation der Betazellfunktion bei Patienten mit Diabetes mellitus Typ 2, für deren Bestimmung es bisher keine einfach anwendbare Methode gibt. Die Clamp-Methode erfordert eine kontinuierliche Überwachung und ist daher nicht geeignet für die Anwendung in der täglichen Klinikroutine. Nateglinide ist ein Derivat der Aminosäure D-Phenylalanin, das durch direkte Wirkung an den Betazellen der Langerhanns’schen Inseln des Pankreas die Insulinsekretion vor allem in der frühen Phase der Freisetzung stimuliert. Ziel der Arbeit war die Überprüfung eines Nateglinide-stimulierten oralen Glucosetole-ranztests als Instrument zur ambulanten Bestimmung der stimulierbaren Betazellkapa-zität sowie sekundär die Bestimmung von Grenzwerten für Blutzucker und Insulinsek-retion für die Entscheidung der Therapieeskalation einer oralen Therapie hin zu einer Insulin(unterstützten) Therapie. Im Rahmen dieser Studie führten wir an 30 gesunden Kontrollpersonen und 45 Patien-ten mit Diabetes mellitus Typ 2, die entweder diätetisch oder mit oralen Antidiabetika behandelt wurden, einen modifizierten oralen Glucosetoleranztest (50g) von dreistün-diger Dauer durch, der mit der Gabe von 120mg Nateglinide kombiniert wurde. Es erfolgte die Bestimmung der Basalwerte von Glucose, Insulin und C-Peptid sowie der Spiegel nach 30, 60, 120 und 180 Minuten. Aus den Ergebnissen wurden der HOMA-IR, HOMA-ß-cell-Index sowie die AUC von Insulin, C-Peptid und Glucose bestimmt. Die gesunden Kontrollpersonen wiesen zu allen Testzeitpunkten signifikant niedrigere Glucosewerte auf als die Patienten mit Typ-2-Diabetes (Maximum Glucose: 125,05±25,97 vs. 234,78±64,58mg/dl, p<0,001 und AUC Glucose: 15197,25±2798,9 vs. 34022,05±11142,17mg/dl, p=0,02), die zudem ihr Blutzuckermaximum zu einem späteren Testzeitpunkt erreichten (35,25±17,61 vs. 63,33±31,76 min, p<0,001). Zum Testzeitpunkt 120 Minuten konnte bei 18 Patienten mit Typ-2-Diabetes ein norm-wertiger Blutglucosespiegel <120mg/dl bestimmt werden, 7 hatten Werte vereinbar mit einer IGT und 20 wiesen diabetische Blutglucosespiegel >200mg/dl auf. Es fiel eine signifikante Korrelation vom Zeitpunkt der maximalen Insulinsekretion und dem Blutglucosemaximum auf. Je später der Zeitpunkt der maximalen Insulin- bzw. C-Peptid-Sekretion erreicht wird, desto höher ist die maximale Blutglucosekonzentration. Adipöse Patienten (BMI >30kg/m2) hatten während des gesamten Testverlaufs höhere Blutglucosewerte und eine geringere stimulierbare Insulinsekretionsleistung als die Patienten mit einem niedrigeren BMI. Die untersuchten Patienten mit Typ-2-Diabetes lassen sich in drei Gruppen unterteilen: eine mit vorherrschendem Insulinsekretionsdefizit (Maximum C-Peptid <4ng/ml, n=6), eine mit führender Insulinresistenz (HOMA-IR>2,5, n=16) und eine Gruppe mit einer Kombination aus beiden Störungen (n=3). Die Patienten mit kombinierter Störung hat-ten einen höheren HbA1c als die anderen Gruppen (10,2%±2,38 vs. 6,66%±0,46 und 6,91%±1,24, n.s.) und wiesen über den gesamten Testverlauf höhere Blutglucosewerte auf. Mit dem Ziel, eine Hilfestellung bei der Entscheidung einer Therapieintensivierung bzw. –umstellung auf eine Insulintherapie zu geben, wurde ein Score aufgestellt, der die Parameter Blutzuckerspiegel zum Testzeitpunkt 120 min, maximaler C-Peptidspiegel, HOMA-IR sowie den Steigerungsfaktor von basalem zu maximalem C-Peptidspiegel umfasst. Beurteilt anhand der dort erreichten Punktzahl zeigen einerseits 23 der unter-suchten Patienten ein suffizientes Ansprechen auf die orale antihyperglykämische The-rapie, was die Fortführung der oralen Diabetestherapie unterstützt. Andererseits er-reichten auch 6 Patienten einen Punktebereich, bei dem von einer unzureichenden Betazellsekretion auszugehen ist und somit ein hohes Risiko für ein Sekundärversagen der oralen Diabetestherapie besteht, so dass eine Therapieumstellung auf eine Insu-lin(unterstützte) Therapie empfohlen wird. Basierend auf der limitierten Anzahl an Daten, die wir erhoben haben, empfehlen wir die Umstellung auf eine Insulintherapie, wenn im Nateglinide-Test mindestens drei der folgenden vier Punkte zutreffen: • Blutglucose zum Zeitpunkt 120min >200mg/dl • HOMA-IR >4 • Maximales C-Peptid <4ng/ml • Stimulierte C-Peptid-Steigerung <2fach Die hiesige Studie zeigt, dass der Nateglinide-Test ein in der täglichen Klinikroutine praktikables Instrument zur Evaluation der residualen Betazellfunktion darstellt. Er er-möglicht die gleichzeitige Beurteilung der noch vorhandenen Insulinsekretionskapazität und der Insulinresistenz bei Patienten mit Typ-2-Diabetes. In Kombination mit dem vorgestellten Score kann er helfen, eine Progression des Diabetes mellitus Typ 2 zu verhindern, indem der Zeitpunkt für den Beginn einer Insulintherapie genauer definiert wird.
In the following Magisterarbeit I am going to develop a Concept Empiricist model of conceptual thought, which is in its technical core primarily inspired and motivated by Larry Barsalou‘ s Perceptual Symbol Systems Theory (PSST) (1999, 2008a). But it is not a theory of concepts in the genuine sense only, but it also expands naturally on related topics like the ontology of mind and the problem of intentionality. This is not arbitrarily chosen, but a natural consequence of any contemporary Concept Empiricist theory, for those theories are in kind direct outgrowths of an embodied approach to cognition which yields these consequences – the natural extension to related topics – as will be shown. The roadmap for the Magisterarbeit is going to look like this: First I will delineate the embodied cognition framework. Within embodied cognition there is a plethora of differing attempts at explaining the diverse phenomena of higher and lower cognition which differ in the meanwhile tremendously from each other. Therefore it will be very useful to set clear boundaries between the differing approaches, which range from strong neural embodiment on the one side to a very promiscuous extended mind hypothesis on the other side, in order to make a clear case for Concept Empiricism. It will be also very helpful to set my favoured version of grounded cognition off against classical attempts at the phenomena which are to be explained. Following that I am going to present Larry Barsalou‘s Perceptual Symbol Systems Theory in more detail. I will do that to an extent which allows for an appropriate discussion of concept related phenomena, but which is not too lengthy. I will spare the reader with unnecessary psychological or neurobiological details as long as it is not really necessary for explaining or clarifying the phenomena with which I deal here. Having done this I will discuss at great length conceptual meaning. In doing so I will present a presentational theory of meaning which is anti-realist, internalist and imaginistic. In advertising for this theory I will recur to conceptual methods, intuition as well as to the empirical record. Next and related to this I will develop a resemblance based theory of intentionality which differs also widely from the already established theories of intentionality so far given. Indeed it possess a feature which makes it very distinct and this is, besides its reliance on pattern mapping, the statistical grounding of resemblance which allows a cognitive theory of resemblance which is definite and therefore not open to the counterarguments generally mashalled against related theories, which stress the importance of resemblance. A very distinctive feature of this theory of intentionality is additionally that intentionality is seen as a capacity which emerges naturally form the mental mechanism involved. As we will see, this is a distinctive advantage of it in comparison to other proposal in the field. A discussion of the ontology of mental states follows which is however primarily a discussion of mechanistic explanations and Bechtel‘s and McCauley‘s Heuristic Identity Theory (HIT). Those theories from philosophy of science and philosophy of cognitive science do not only deliver models for the ontology of mental states, but also epistemic criteria for evaluating a theory as superior or inferior. Especially the idea of productive continuity plays a role of pivotal importance in my Magisterarbeit. It might be a bit unfortunate that that an important consideration is discussed nearly at the end of the Magisterarbeit, since I refer to it very often, however, I considered it as equally unfortunate to delay the discussion of meaning and intentionality, which is already protruded by the overview chapter and the more technical parts, even more. Therefore I plead the reader to refer to later parts of the Magisterarbeit when it is necessary in order to understand earlier parts. In the course of writing I have gotten second thoughts regarding the adequacy of an ontology of mental states altogether, especially from the background of the theory of meaning and intentionality delivered here. Therefore I tried to accommodate for ontological concepts by means of a tentative phenomenological interpretation of them. Similar ideas influenced my deliberations regarding meaning too. I hope that this transition towards Phenomenology runs smoothly and that the high level of coherence which is my primary concern and something which I always strive for first is preserved. Further, I have dedicated a main chapter of the Magisterarbeit for possible and actual critics of the ideas brought forth by me. Besides the more classic standard objections there you can find a recent critique of the authors on which I refer most often. Naturally I try to refute any single criticism brought forth and I hope that the reader will approve my objection to the objections. I will round off the Magisterarbeit with some concluding remarks and prospects for future research.
Die vorliegende Untersuchung vergleicht den politischen Sprachgebrauch von CDU, SPD, Bündnis90/DIE GRÜNEN sowie deren Jugendorganisationen während der 13. Wahlperiode (1994-1998). Unter Verwendung einer computergestützten Textanalysemethode wird dazu ein Textcorpus, bestehend aus 18 parteiprogrammatischen Äußerungen, auf sprachliche Strategien der Persuation und Verhaltensteuerung hin untersucht. Im Kern der Untersuchung steht die Frage, welche sprachlichen Werkzeuge Parteien verwenden, um die Wahlentscheidung junger Wähler und Erstwähler zu beeinflussen. So können Modalverben auf appellative Strukuren verweisen, Konjunktionen (aber , dennoch) ein Indiz für eine dogmatische Denkweise sein, Personal- und Possesivpronomen über Distanziertheit, Verbundenheit und den Gruppenbezug Auskunft erteilen. Inhaltliche Nähe zu den zentralen Problemfelder der Jugendlichen erhebt der Vergleich mit den Ergebnissen der 12. Shell-Jugendstudie des Jahres 1997.
Background: The faunal and floral relationship of northward-drifting India with its neighboring continents is of general biogeographic interest as an important driver of regional biodiversity. However, direct biogeographic connectivity of India and Southeast Asia during the Cenozoic remains largely unexplored. We investigate timing, direction and mechanisms of faunal exchange between India and Southeast Asia, based on a molecular phylogeny, molecular clock-derived time estimates and biogeographic reconstructions of the Asian freshwater crab family Gecarcinucidae. Results: Although the Gecarcinucidae are not an element of an ancient Gondwana fauna, their subfamily Gecarcinucinae, and probably also the Liotelphusinae, evolved on the Indian Subcontinent and subsequently dispersed to Southeast Asia. Estimated by a model testing approach, this dispersal event took place during the Middle Eocene, and thus before the final collision of India and the Tibet-part of Eurasia. Conclusions: We postulate that the India and Southeast Asia were close enough for exchange of freshwater organisms during the Middle Eocene, before the final Indian--Eurasian collision. Our data support geological models that assume the Indian plate having tracked along Southeast Asia during its move northwards.
Background: Complex care management is seen as an approach to face the challenges of an ageing society with increasing numbers of patients with complex care needs. The Medical Research Council in the United Kingdom has proposed a framework for the development and evaluation of complex interventions that will be used to develop and evaluate a primary care-based complex care management program for chronically ill patients at high risk for future hospitalization in Germany. Methods and design: We present a multi-method procedure to develop a complex care management program to implement interventions aimed at reducing potentially avoidable hospitalizations for primary care patients with type 2 diabetes mellitus, chronic obstructive pulmonary disease, or chronic heart failure and a high likelihood of hospitalization. The procedure will start with reflection about underlying precipitating factors of hospitalizations and how they may be targeted by the planned intervention (pre-clinical phase). An intervention model will then be developed (phase I) based on theory, literature, and exploratory studies (phase II). Exploratory studies are planned that entail the recruitment of 200 patients from 10 general practices. Eligible patients will be identified using two ways of 'case finding': software based predictive modelling and physicians' proposal of patients based on clinical experience. The resulting subpopulations will be compared regarding healthcare utilization, care needs and resources using insurance claims data, a patient survey, and chart review. Qualitative studies with healthcare professionals and patients will be undertaken to identify potential barriers and enablers for optimal performance of the complex care management program. Discussion: This multi-method procedure will support the development of a primary care-based care management program enabling the implementation of interventions that will potentially reduce avoidable hospitalizations.
The central difference between objectivist cognitivist semantics and embodied cognition consists in the fact that the latter is, in contrast to the former, mindful of binding meaning to context-sensitive mental systems. According to Lakoff/Johnson's experientialism, conceptual structures arise from preconceptual kinesthetic image-schematic and basic-level structures. Gallese and Lakoff introduced the notion of exploiting sensorimotor structures for higherlevel cognition. Three different types of X-schemas realise three types of environmentally embedded simulation: Areas that control movements in peri-personal space; canonical neurons of the ventral premotor cortex that fire when a graspable object is represented; the firing of mirror neurons while perceiving certain movements of conspecifics. ...
In the present work, the problem of protein folding is addressed from the point of view of equilibrium thermodynamics. The conformation of a globular protein in solution at common temperatures is quite complicated without any geometrical symmetry, but it is an ordered state in the sense of its biological activity. This complicated conformation of a single protein molecule is destroyed upon increasing the temperature or by the addition of appropriate chemical agents, as is revealed by the loss of its activity and change of the physical properties, and so on. Once the complicated native structures having biological activity are lost, it would be natural to suppose that the native structure could hardly be restored. Nevertheless, pioneers, such as Anson and Mirsky, recognized as early as in 1925 that this was not always the case. If one defines the folded and unfolded states of a protein as two distinct phases of a system, then under the variation of temperature the system is transformed from one phase state into another and vice versa. The process of protein folding is accompanied by the release or absorption of a certain amount of energy, corresponding to the first-oder-type phase transitions in the bulk. Knowing the partition function of the system one can evaluate its energy and heat capacity under different temperatures. This task was performed in this work. The results of the developed statistical mechanics model were compared with the results of molecular dynamic simulations of alanine poylpeptides. In particular, the dependencies on temperature of the total energy of the system and heat capacity were compared for alanine polypeptides consisting of 21, 30, 40, 50 and 100 amino acids. The good correspondence of the results of the theoretical model with the results of molecular dynamics simulations allowed to validate the assumptions made about the system and to establish the accuracy range of the theory. In order to perform the comparison of the results of theoretical model and the molecular dynamics simulations it is necessary to perform the efficient analysis of the results of molecular dynamics simulations. This task was also addressed in the present work. In particular, different ways to obtain dependence of the heat capacity on temperature from molecular dynamics simulations are discussed and the most efficient one is proposed. The present thesis reports the result of molecular dynamic simulations for not only alanine polypeptides by also for valine and leucine polypeptides. In valine and leucine polypeptides, it is also possible to observe the helix↔random coil transitions with the increase of temperature. The current thesis presents a work that starts with the investigation of the fundamental degrees of freedom in polypeptides that are responsible for the conformational transitions. Then this knowledge is applied for the statistical mechanics description of helix↔coil transitions in polypeptides. Finally, the theoretical formalism is generalized for the case of proteins in water environment and the comparison of the results of the statistical mechanics model with the experimental measurements of the heat capacity on temperature dependencies for two globular proteins is performed. The presented formalism is based on fundamental physical properties of the system and provides the possibility to describe the folding↔unfolding transitions quantitatively. The combination of these two facts is the major novelty of the presented approach in comparison to the existing ones. The “transparent” physical nature of the formalism provides a possibility to further apply it to a large variety of systems and processes. For instance, it can be used for investigation of the influence of the mutations in the proteins on their stability. This task is of primary importance for design of novel proteins and drug delivering molecules in medicine. It can provide further insights into the problem of protein aggregation and formation of amyloids. The problem of protein aggregation is closely associated with various illnesses such as Alzheimer and mad cow disease. With certain modifications, the presented theoretical method can be applied to the description of the protein crystallization process, which is important for the determination of the structure of proteins with X-Rays. There many other possible applications of the ideas described in the thesis. For instance, the similar formalism can be developed for the description of melting and unzipping of DNA, growth of nanotubes, formation of fullerenes, etc.
Das Ziel dieser retrospektiven Untersuchung ist, die medikamentöse Therapie des neonatalen Entzugsyndroms mittels Clonidin und Chloralhydrat mit der sehr häufig angewendeten Kombinationstherapie aus Morphin und Phenobarbital zu vergleichen. Im dem Zeitraum zwischen 1998 und 2008 wurden in unserer Klinik 133 Neugeborene mit einem neonatalen Entzugssyndrom behandelt. Bei allen Patienten handelte es sich um Neugeborene drogenabhängiger Mütter, welche während der Schwangerschaft mit Methadon substituiert wurden. Bei 29 Patienten wurde eine Therapie mit Clonidin und Chloralhydrat und bei 64 Patienten eine Entzugstherapie mittels Morphin und Phenobarbital durchgeführt. In der Clonidingruppe konnte eine signifikant kürzere Behandlungsdauer (Median: 14 d vs. 35 d) festgestellt werden. Entsprechend war auch die gesamte Aufenthaltsdauer in der Clonidingruppe deutlich kürzer (Median: 32 d vs. 44 d). Außerdem konnte in der Clonidingruppe ein deutlich milderer Verlauf der Entzugssymptomatik festgestellt werden.
On the backdrop of the 2008 financial crisis this paper introduces an understanding of societal crises as a reduction in the meaning production of social entities, which can either be internally or externally provoked. The emergence of constitutions and, more generally, constitutional structures, can be understood as responses to both forms of crisis. This is the case because they are double-edged structures which are simultaneously oriented towards the maintenance of internal order and stability within a given social entity at the same time as they frame the transfer of the meaning components between the social entities and their environments. Thus, the 2008 financial crisis indicates a failure of constitutional bonding. When observed from an overall structural perspective, the reasons for this failure can be traced back to an increased discrepancy between the structural composition of world society and the constitutional structures in place. The crisis reflects a failure to respond to two simultaneous, inter-related and mutually re-inforcing structural transformations. First, there is the increased globalisation, which has led to massive dis-locations in the relative centrality of the different national configurations for the reproductive processes of functional systems. Second, there is a structural transformation of the transnational layer of world society through a reduced reliance on the centre/periphery differentiation and an increased reliance on functional differentiation. One of the many consequences of this development is the emergence of new forms of transnational law and politics. A new constitutional architecture which reflects these transformations is needed in order to ensure an adequate constitutional bonding of economic processes, as well as of other social processes.
Die Herausbildung normativer Ordnungen : zur Idee eines interdisziplinären Forschungsprogramms
(2010)
Ein geistes- und sozialwissenschaftliches Forschungsprogramm betritt mit der These, dass wir in einer Zeit tiefgreifender sozialer Veränderungen leben, kein Neuland. Ein thematischer Fokus auf die Frage der Herausbildung normativer Ordnungen mit Bezug auf die entsprechenden Verschiebungen, Umbrüche und Konflikte in verschiedenen Gesellschaften und auf transnationaler Ebene bringt dagegen etwas Neues und Wichtiges ans Licht. Das ist jedenfalls unsere Überzeugung.
Background: Prospective, observational studies that enroll large numbers of patients with few exclusion criteria may better reflect actual ongoing clinical experience than randomized clinical trials. Our purpose was to obtain efficacy and safety information from a cohort of subjects exposed to latanoprost/timolol fixed combination (FC) for [greater than or equal to]18 months using a prospective, observational design. Methods: In all, 577 office-based ophthalmologists in Germany switched 2339 patients with glaucoma or ocular hypertension to latanoprost/timolol FC for medical reasons. Follow-up visits were scheduled for every 6 months over 24 months; physicians followed usual care routines. Intraocular pressure (IOP), visual field status, optic nerve head findings, and adverse events were recorded. Efficacy parameters were evaluated for the per protocol (PP) population; the safety population included subjects receiving [greater than or equal to]1 drop of FC. Physicians rated efficacy, tolerability, and subject compliance at month 24. Results: Of the 2339 subjects switched to latanoprost/timolol FC (safety population), the primary reasons for switching were inadequate IOP reduction (78.2%) and desire to simplify treatment with once-daily dosing (29.4%; multiple reasons possible). In all, 1317 (56.3%) subjects completed the study, and 1028 (44.0%) were included in the PP population. Most discontinuations were due to loss to follow-up. Change in mean IOP from baseline to month 6 was -4.0 +/- 4.31 mmHg, a reduction that was maintained throughout (P<0.05 for change at all time points). By investigator assessments, optic disc parameters and visual field were stable over 24 months, and there was no relationship between IOP reduction over 24 months and development of a visual field defect. More than 90% of physicians rated latanoprost/timolol FC as "very good" or "good" for efficacy (PP population), tolerability, and compliance. The FC was safe and well tolerated. No change in iris color was reported by most subjects (83.1%) at month 24. Conclusions: Over 24 months, latanoprost/timolol FC effectively lowers IOP levels and is well tolerated in patients with glaucoma or ocular hypertension who change from their previous ocular hypotensive therapy for medical reasons. Investigator assessments found optic disc parameters and visual field to be stable throughout 24 months of follow-up.
Background: FibroTest (FT) is the most frequently used serum fibrosis marker and consists of an algorithm of five fibrosis markers (alfa2-macroglobulin, apolipoproteinA1, haptoglobin, GGT, bilirubin). The Enhanced Liver Fibrosis (ELF) test consists of an algorithm of three fibrosis markers (hyaluronic acid, amino-terminal propeptide-of-type-III-collagen, tissue-inhibitor of matrix-metaloproteinase-1). While a systematic review has shown comparable results for both individual markers, there has been no direct comparison of both markers. Methods: In the present study, the ELF-test was analyzed retrospectively in patients with chronic liver disease, who received a liver biopsy, transient elastography (TE) and the FibroTest using histology as the reference method. Histology was classified according to METAVIR and the Ludwig's classification (F0-F4) for patients with chronic hepatitis C and B virus (HCV, HBV) infection and primary biliary cirrhosis (PBC), respectively. Results: Seventy-four patients were analysed: 36 with HCV, 10 with HBV, and 28 with PBC. The accuracy (AUROC) for the diagnosis of significant fibrosis (F[greater than or equal to]2) for ELF and FibroTest was 0.78 (95%CI:0.67-0.89) and 0.69 (95%-CI:0.57-0.82), respectively (difference not statistically significant, n.s.). The AUROC for the diagnosis of liver cirrhosis was 0.92 (95%CI:0.83-1,00), and 0.91 (95%CI:0.83-0.99), respectively (n.s.). For 66 patients with reliable TE measurements the AUROC for the diagnosis of significant fibrosis (cirrhosis) for TE, ELF and FT were 0.80 (0.94), 0.76 (0.92), and 0.67 (0.91), respectively (n.s.). Conclusion: FibroTest and ELF can be performed with comparable diagnostic accuracy for the non-invasive staging of liver fibrosis. Serum tests are informative in a higher proportion of patients than transient elastography.
Active chlorine species play a dominant role in the catalytic destruction of stratospheric ozone in the polar vortices during the late winter and early spring seasons. Recently, the correct understanding of the ClO dimer cycle was challenged by the release of new laboratory absorption cross sections (Pope et al., 2007) yielding significant model underestimates of observed ClO and ozone loss (von Hobe et al., 2007). Under this aspect, nocturnal Arctic stratospheric limb emission measurements carried out by the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) from Kiruna (Sweden) on 11 January 2001 and 20/21 March 2003 have been reanalyzed with regard to the chlorine reservoir species ClONO2 and the active species, ClO and ClOOCl (Cl2O2). New laboratory measurements of IR absorption cross sections of ClOOCl for various temperatures and pressures allowed for the first time the retrieval of ClOOCl mixing ratios from remote sensing measurements. High values of active chlorine (ClOx) of roughly 2.3 ppbv at 20 km were observed by MIPAS-B in the cold mid-winter Arctic vortex on 11 January 2001. While nighttime ClOOCl shows enhanced values of nearly 1.1 ppbv at 20 km, ClONO2 mixing ratios are less than 0.1 ppbv at this altitude. In contrast, high ClONO2 mixing ratios of nearly 2.4 ppbv at 20 km have been observed in the late winter Arctic vortex on 20 March 2003. No significant ClOx amounts are detectable on this date since most of the active chlorine has already recovered to its main reservoir species ClONO2. The observed values of ClOx and ClONO2 are in line with the established polar chlorine chemistry. The thermal equilibrium constants between the dimer formation and its dissociation, as derived from the balloon measurements, are on the lower side of reported data and in good agreement with values recommended by von Hobe et al. (2007). Calculations with the ECHAM/MESSy Atmospheric Chemistry model (EMAC) using established kinetics show similar chlorine activation and deactivation, compared to the measurements in January 2001 and March 2003, respectively.
Atmospheric observation-based global SF6 emissions - comparison of top-down and bottom-up estimates
(2009)
Emissions of sulphur hexafluoride (SF6), one of the strongest greenhouse gases on a per molecule basis, are targeted to be collectively reduced under the Kyoto Protocol. Because of its long atmospheric lifetime (≈3000 years), the accumulation of SF6 in the atmosphere is a direct measure of its global emissions. Examination of our extended data set of globally distributed high-precision SF6 observations shows an increase in SF6 abundance from near zero in the 1970s to a global mean of 6.7 ppt by the end of 2008. In-depth evaluation of our long-term data records shows that the global source of SF6 decreased after 1995, most likely due to SF6 emission reductions in industrialised countries, but increased again after 1998. By subtracting those emissions reported by Annex I countries to the United Nations Framework Convention of Climatic Change (UNFCCC) from our observation-inferred SF6 source leaves a surprisingly large gap of more than 70–80% of non-reported SF6 emissions in the last decade.