Optimal adaptive control with separable drift uncertainty

We consider a problem of stochastic optimal control with separable drift uncertainty in strong formulation on a finite horizon. The drift coefficient of the state $Y^{u}$ is multiplicatively influenced by an unknown random variable $\lambda$, while admissible controls $u$ are required to be adapted to the observation filtration. Choosing a control actively influences the state and information acquisition simultaneously and comes with a learning effect. The problem, initially non-Markovian, is embedded into a higher-dimensional Markovian, full information control problem with control-dependent filtration and noise. To that problem, we apply the stochastic Perron method to characterize the value function as the unique viscosity solution to the HJB equation, explicitly construct $\varepsilon$-optimal controls and show that the values of strong and weak formulations agree. Numerical illustrations show a significant difference between the adaptive control and the certainty equivalence control

Precision spectral manipulation of optical pulses using a coherent photon echo memory

Photon echo schemes are excellent candidates for high efficiency coherent optical memory. They are capable of high-bandwidth multi-pulse storage, pulse resequencing and have been shown theoretically to be compatible with quantum information applications. One particular photon echo scheme is the gradient echo memory (GEM). In this system, an atomic frequency gradient is induced in the direction of light propagation leading to a Fourier decomposition of the optical spectrum along the length of the storage medium. This Fourier encoding allows precision spectral manipulation of the stored light. In this letter, we show frequency shifting, spectral compression, spectral splitting, and fine dispersion control of optical pulses using GEM

Auf dem Weg zur Zweidrittel-Demokratie: Wege aus der Partizipationskrise

"Die aktive Teilnahme am politischen Prozess nimmt kontinuierlich ab: Die Wahlbeteiligung geht zurück, die soziale Selektivität der Partizipation verschärft sich, die Volksparteien verlieren an Bindungskraft und beklagen seit Jahren einen massiven Mitgliederschwund. Die Stärkung direkt-demokratischer Elemente oder alternativer politischer Betätigungsformen wären keine probaten Gegenmittel. Im Gegenteil – diese Beteiligungsformen sind noch stärker einer sozialen Selektion unterworfen. Wichtig wäre – neben einer deutlicheren Profilierung der Parteien - eine breit gefächerte präventive Politik, die der dauerhaften sozialen Exklusion großer Bevölkerungsteile entgegenwirkt."[Autorenreferat]"Political participation in developed democracies is steadily decreasing. Voter turnout is in decline, social selectivity of political participation is on the rise. The major political parties face the challenge of dwindling membership. Strengthening elements of direct democracy or fostering alternative methods of political involvement are insufficient. On the contrary, these forms of participation are even more prone to exclude the poor and less well educated. What is needed is a broad range of preventive social, fiscal and educational policies which counteract social exclusion of a significant part of the population."[author´s abstract

Research on Gas Hydrate Plug Formation under Pipeline-Like Conditions

Hydrates of natural gases like methane have become subject of great interest over the last few decades, mainly because of their potential as energy resource. The exploitation of these natural gases from gas hydrates is seen as a promising mean to solve future energetic problems. Furthermore, gas hydrates play an important role in gas transportation and gas storage: in pipelines, particularly in tubes and valves, gas hydrates are formed and obstruct the gas flow. This phenomenon is called “plugging” and causes high operational expenditure as well as precarious safety conditions. In this work, research on the formation of gas hydrates under pipeline-like conditions, with the aim to predict induction times as a mean to evaluate the plugging potential, is described

Diktatorendämmerung: Nordafrika und Nahost: schwache Regime und starke Oppositionsbewegungen

"Die jüngsten Ereignisse im Nahen Osten und in Nordafrika haben sogar versierte Beobachter überrascht. Eigentlich galt die Region als ein Hort stabiler Diktaturen. Doch innerhalb von Wochen gelang es den Bürgern, zwei Diktatoren aus dem Amt zu jagen; andere Autokraten könnten bald folgen. Der konstante Niedergang der politischen und wirtschaftlichen Machtbasis der autokratischen Regime in Verbindung mit der Erhebung einer mit Web-2.0 vertrauten Jugendbewegung hat letztendlich eine überraschende Möglichkeit für weitreichende Reformen ermöglicht. Ob diese Chance ergriffen wird, bleibt abzuwarten." (Autorenreferat)"Recent events in the Middle East and North Africa have surprised even adept observers. The region was presumably a harbor of stable dictatorships. Yet within weeks, citizens forced two dictators from power and other autocrats might soon follow. The steady decline of the autocratic regimes' political and economic power base, in conjunction with the rise of a Web 2.0-experienced youth movement, has ultimately opened an unexpected window of opportunity for far-reaching reforms. Whether this opportunity will be seized upon remains to be seen." (author's abstract

Protective Effects of Statin Therapy in Cirrhosis Are Limited by a Common SLCO1B1 Transporter Variant

Complications of cirrhosis and portal hypertension (PH) can be reduced by statin therapy. The common loss-of-function variant p.V174A in the solute carrier organic anion transporter gene 1B1 (SLCO1B1) gene encoding the organic anion transporting polypeptide 1B1 results in decreased hepatic uptake of statins. Our specific aim was to assess the impact of this variant in patients with cirrhosis and statin treatment while controlling for the stage of cirrhosis and other potential confounders with propensity score matching (PSM), availing of a large cohort of genotyped study patients. In total, from 1,088 patients with cirrhosis in two German academic medical centers, PSM yielded 154 patients taking statins and 154 matched controls. The effect on PH was assessed by the liver stiffness–spleen size–to–platelet score (LSPS), and complications of cirrhosis were retrospectively recorded applying consensus criteria. As hypothesized, patients on statin treatment presented less frequently with signs of PH: Esophageal varices (41% vs. 62%; P < 0.001) were less common, and LSPS (4.8 ± 11.5 vs. 5.6 ± 6.4; P = 0.01) was reduced. Correspondingly, decompensation events were also reduced in patients on statins (odds ratio [OR] = 0.54, 95% confidence interval [CI] 0.32-0.90; P = 0.02). When the variant in SLCO1B1 was present in patients on statins, esophageal varices (OR = 2.68, 95% CI 1.24-5.81; P = 0.01) and bacterial infections (OR = 2.50, 95% CI 1.14-5.47; P = 0.02) were more common as compared with wild type carriers on statins. Conclusion: In this cohort, signs and complications of PH were reduced in patients with cirrhosis treated with statins. Notably, this effect was diminished by the common loss-of-function variant in SLCO1B1. Further prospective studies in independent cohorts are warranted to confirm these genotype-specific observations

Clinical and morphological findings on mustard gas [bis (2-chloroethyl) sulfide] poisoning

n 1984 and 1985, a total of eleven Iranian patients were transferred to hospitals in Munich, Germany, after a reported gas attack in the Iran-Iraq war. The initial symptoms and pretreatment in Teheran, Iran, as well as the admittance examination data, the clinical courses of the patients, and the clinical laboratory data in Germany, are reported. The main injuries were to the skin, the eyes, and the respiratory tract. One patient stopped breathing suddenly on the third day of treatment (eight days after the exposure). A large piece of mucous membrane blocking a bronchus was removed during an immediate bronchoscopy, but attempts at resuscitation failed. The most important autopsy findings in this case were severe pseudomembranous inflammation of the trachea and the bronchial tubes. The histological findings are reported. Chemical proof of the poison (mustard gas) was established. A review of the history of chemical warfare, the physical and chemical properties of mustard gas, and a literature survey of clinical findings (including, especially, experiences from World Wars I and II) contribute to the understanding of the actual cases

Anaerobic carboxydotrophy in sulfur-respiring haloarchaea from hypersaline lakes

Anaerobic carboxydotrophy is a widespread catabolic trait in bacteria, with two dominant pathways: hydrogenogenic and acetogenic. The marginal mode by direct oxidation to CO2 using an external e-acceptor has only a few examples. Use of sulfidic sediments from two types of hypersaline lakes in anaerobic enrichments with CO as an e-donor and elemental sulfur as an e-acceptor led to isolation of two pure cultures of anaerobic carboxydotrophs belonging to two genera of sulfur-reducing haloarchaea: Halanaeroarchaeum sp. HSR-CO from salt lakes and Halalkaliarchaeum sp. AArc-CO from soda lakes. Anaerobic growth of extremely halophilic archaea with CO was obligatory depended on the presence of elemental sulfur as the electron acceptor and yeast extract as the carbon source. CO served as a direct electron donor and H2 was not generated from CO when cells were incubated with or without sulfur. The genomes of the isolates encode a catalytic Ni,Fe-CODH subunit CooS (distantly related to bacterial homologs) and its Ni-incorporating chaperone CooC (related to methanogenic homologs) within a single genomic locus. Similar loci were also present in a genome of the type species of Halalkaliarchaeum closely related to AArc-CO, and the ability for anaerobic sulfur-dependent carboxydotrophy was confirmed for three different strains of this genus. Moreover, similar proteins are encoded in three of the four genomes of recently described carbohydrate-utilizing sulfur-reducing haloarchaea belonging to the genus Halapricum and in two yet undescribed haloarchaeal species. Overall, this work demonstrated for the first time the potential for anaerobic sulfur-dependent carboxydotrophy in extremely halophilic archaea.Accepted Author ManuscriptBT/Environmental Biotechnolog