Decay of correlations in the dissipative two-state system

We study the equilibrium correlation function of the polaron-dressed tunnelling operator in the dissipative two-state system and compare the asymptoptic dynamics with that of the position correlations. For an Ohmic spectral density with the damping strength $K=1/2$, the correlation functions are obtained in analytic form for all times at any $T$ and any bias. For $K<1$, the asymptotic dynamics is found by using a diagrammatic approach within a Coulomb gas representation. At T=0, the tunnelling or coherence correlations drop as $t^{-2K}$, whereas the position correlations show universal decay $\propto t^{-2}$. The former decay law is a signature of unscreened attractive charge-charge interactions, while the latter is due to unscreened dipole-dipole interactions.Comment: 5 pages, 5 figures, to be published in Europhys. Let

Power Converters of the Main Dipole and Quadrupole Magnet Strings of the Antiproton Decelerator at CERN

The two main power converters for the dipoles (D) and quadrupoles (Q) are presented as part of the complex power converter system of the Antiproton Decelerator. The operational requirements and the performance specifications for deceleration from 3.5 to 0.1 GeV/c are discussed. The layout and design of the power part, consisting of a 12-pulse thyristor rectifier and a switch-mode parallel active filter (AF), and of the precision regulation are described. The alternatives for integrating the AF into the current and voltage regulation loops are outlined. Problems encountered and results of tests are reported

Seawater‐Degradable Polymers—Fighting the Marine Plastic Pollution

Polymers shape human life but they also have been identified as pollutants in the oceans due to their long lifetime and low degradability. Recently, various researchers have studied the impact of (micro)plastics on marine life, biodiversity, and potential toxicity. Even if the consequences are still heavily discussed, prevention of unnecessary waste is desired. Especially, newly designed polymers that degrade in seawater are discussed as potential alternatives to commodity polymers in certain applications. Biodegradable polymers that degrade in vivo (used for biomedical applications) or during composting often exhibit too slow degradation rates in seawater. To date, no comprehensive summary for the degradation performance of polymers in seawater has been reported, nor are the studies for seawater-degradation following uniform standards. This review summarizes concepts, mechanisms, and other factors affecting the degradation process in seawater of several biodegradable polymers or polymer blends. As most of such materials cannot degrade or degrade too slowly, strategies and innovative routes for the preparation of seawater-degradable polymers with rapid degradation in natural environments are reviewed. It is believed that this selection will help to further understand and drive the development of seawater-degradable polymers

Influenza vaccines: the effect of vaccine dose on antibody response in primed populations during the ongoing interpandemic period. A review of the literature.

Health authorities tend to favour an increase of the antigen dose in inactivated influenza vaccines from or = 75%) for a 10 micrograms HA dose of influenza A vaccine components. For both response and protection rates, an increase of the antigenic load from 10 to 15 micrograms HA was not associated with a meaningful increase of seroresponse: in 38 out of 39 stratification groups, the increase of response and/or protection rate varied between -9% and +8%, with a median of 1.5%. These results do not justify the expectation that a vaccine dose of 15 micrograms HA per strain would be clinically superior to a dose of 10 micrograms HA. Only in a group of immune-compromised patients on chronic intermittent haemodialysis were results in favour of a higher dose found, which may justify further evaluation in this special population

Climate change driven effects on transport, fate and biogeochemistry of trace element contaminants in coastal marine ecosystems

Human activities and climate change substantially threaten coastal areas, impacting ecosystem functions, services, and human-wellbeing. Trace elements, from both natural and anthropogenic sources, can contaminate coastal regions, and at high concentrations may become toxic to marine biota. Climate change is likely to affect the sources, sinks and cycling of trace elements in coastal systems: for example, riverine runoff is set to increase as precipitation in the Arctic intensifies, and more frequent extreme floods are expected to activate previously deeply buried trace elements. Furthermore, changes in human activity under a warming climate, such as increased Arctic shipping and potential geoengineering projects such as ocean alkalinity enhancement, will likely introduce more trace elements to coastal ecosystems. Advancing our understanding of trace element cycling is at present limited by factors including lack of data coverage in the Global South, challenges in studying multi-stressor effects and ecosystem responses, lack of long-term data, and the difficulty in parametrizing robust models in coastal environments

How mathematical modelling elucidates signalling in Bacillus subtilis

P>Appropriate stimulus perception, signal processing and transduction ensure optimal adaptation of bacteria to environmental challenges. In the Gram-positive model bacterium Bacillus subtilis signalling networks and molecular interactions therein are well-studied, making this species a suitable candidate for the application of mathematical modelling. Here, we review systems biology approaches, focusing on chemotaxis, sporulation, sigma B-dependent general stress response and competence. Processes like chemotaxis and Z-ring assembly depend critically on the subcellular localization of proteins. Environmental response strategies, including sporulation and competence, are characterized by phenotypic heterogeneity in isogenic cultures. The examples of mathematical modelling also include investigations that have demonstrated how operon structure and signalling dynamics are intricately interwoven to establish optimal responses. Our review illustrates that these interdisciplinary approaches offer new insights into the response of B. subtilis to environmental challenges. These case studies reveal modelling as a tool to increase the understanding of complex systems, to help formulating hypotheses and to guide the design of more directed experiments that test predictions