Investigation of low temperature quantum crossover in Josephson junctions

The evidence for macroscopic quantum tunneling (MQT) in Josephson junctions at low temperatures has been reassessed. Swept bias escape distributions have been modeled with an algorithm-based simulation and the results compared with data from representative published experiments. Signatures expected of a crossover to MQT are not found in the analyzed data.Comment: 7 pages, 6 figure

Long Josephson junctions with spatially inhomogeneous driving

The phase dynamics of a long Josephson junction with spatially inhomogeneously distributed bias current is considered for the case of a dense soliton chain (regime of the Flux Flow oscillator). To derive the analytical solution of the corresponding sine-Gordon equation the Poincare method has been used. In the range of the validity of the theory good coincidence between analytically derived and numerically computed current-voltage characteristics have been demonstrated for the simplest example of unitstep function distribution of bias current (unbiased tail). It is shown, that for the considered example of bias current distribution, there is an optimal length of unbiased tail that maximizes the amplitude of the main harmonic and minimizes the dynamical resistance (thus leading to reduction of a linewidth).Comment: 7 pages, 5 figure

A classical statistical model for distributions of escape events in swept-bias Josephson junctions

We have developed a model for experiments in which the bias current applied to a Josephson junction is slowly increased from zero until the junction switches from its superconducting zero-voltage state, and the bias value at which this occurs is recorded. Repetition of such measurements yields experimentally determined probability distributions for the bias current at the moment of escape. Our model provides an explanation for available data on the temperature dependence of these escape peaks. When applied microwaves are included we observe an additional peak in the escape distributions and demonstrate that this peak matches experimental observations. The results suggest that experimentally observed switching distributions, with and without applied microwaves, can be understood within classical mechanics and may not exhibit phenomena that demand an exclusively quantum mechanical interpretation.Comment: Eight pages, eight figure

Classical analysis of phase-locking transients and Rabi-type oscillations in microwave-driven Josephson junctions

We present a classical analysis of the transient response of Josephson junctions perturbed by microwaves and thermal fluctuations. The results include a specific low frequency modulation in phase and amplitude behavior of a junction in its zero-voltage state. This transient modulation frequency is linked directly to an observed variation in the probability for the system to switch to its non-zero voltage state. Complementing previous work on linking classical analysis to the experimental observations of Rabi-oscillations, this expanded perturbation method also provides closed form analytical results for attenuation of the modulations and the Rabi-type oscillation frequency. Results of perturbation analysis are compared directly (and quantitatively) to numerical simulations of the classical model as well as published experimental data, suggesting that transients to phase-locking are closely related to the observed oscillations.Comment: 18 pages total, 8 figures (typos corrected; minor revisions to figures and equations

Investigation of resonant and transient phenomena in Josephson junction flux qubits

We present an analytical and computational study of resonances and transient responses in a classical Josephson junction system. A theoretical basis for resonances in a superconducting loop with three junctions is presented, outlining both the direct relationship between the dynamics of single- and multi-junction systems, and the direct relationships between observations of the classical counterparts to Rabi oscillations, Ramsey fringes, and spin echo oscillations in this class of systems. We show simulations data along with analytical analyses of the classical model, and the results are related to previously reported experiments conducted on three junction loops. We further investigate the effect of off-resonant microwave perturbations to, e.g., the Rabi-type response of the Josephson system, and we relate this response back to the nonlinear and multi-valued resonance behavior previously reported for a single Josephson junction. The close relationships between single and multi-junction behavior demonstrates the underlying dynamical mechanism for a whole class of classical counterparts to expected quantum mechanical observations in a variety of systems; namely the resonant and transient behavior of a particle in an anharmonic potential well with subsequent escape.Comment: 11 pages, seven figure

Methodology for the comparative assessment of the Satellite Power System (SPS) and alternative technologies

The energy systems concerned are the satellite power system, several coal technologies, geothermal energy, fission, fusion, terrestrial solar systems, and ocean thermal energy conversion. Guidelines are suggested for the characterization of these systems, side-by-side analysis, alternative futures analysis, and integration and aggregation of data. A description of the methods for assessing the technical, economic, environmental, societal, and institutional issues surrounding the development of the selected energy technologies is presented

Di(2-ethylhexyl)phthalate (DEHP) and di-n-butylphthalate (DBP) exposure through diet in hospital patients.

Ready-to-eat packed meals intended to hospital patients were studied over a two-weeks period to measure the contents of di-(2-ethylhexyl) phthalate (DEHP) and di-n-butylphthalate (DBP) and to evaluate their daily intake by total diet. The packaging consisted of polyethylene terephthalate (PET) dishes sealed with polypropylene (PP) foil. The DEHP mean concentrations in total meals varied from 0.061 ± 0.028 to 0.307 ± 0.138 μg/g. wet. weight (wet wt.); the DBP mean levels varied from 0.025 ± 0.018 to 0.174 ± 0.091 μg/g. wet. wt. Highest levels of concentration for DEHP and DBP were found in bread with mean values of 0.307 ± 0.138 μg/g. wet. wt. and 0.174 ± 0.091 μg/g. wet. wt. for DEHP and DBP, respectively. The daily intake for DEHP was 3.1 ± 0.9 μg/kg. bw and 1.5 ± 0.5 μg/kg. bw for DBP.The mean ± sd incidence of DEHP and DBP intake via hospital meals on the respective EFSA TDI was 6 ± 2% (range 4-11%), and 15 ± 5% (range 8-24%), respectively. Even if for hospital patients the major route of exposure may be represented by medical devices, the influence of the diet could have a significant value on TD

Pedestrians moving in dark: Balancing measures and playing games on lattices

We present two conceptually new modeling approaches aimed at describing the motion of pedestrians in obscured corridors: * a Becker-D\"{o}ring-type dynamics * a probabilistic cellular automaton model. In both models the group formation is affected by a threshold. The pedestrians are supposed to have very limited knowledge about their current position and their neighborhood; they can form groups up to a certain size and they can leave them. Their main goal is to find the exit of the corridor. Although being of mathematically different character, the discussion of both models shows that it seems to be a disadvantage for the individual to adhere to larger groups. We illustrate this effect numerically by solving both model systems. Finally we list some of our main open questions and conjectures

The Modulatory Effect of Ellagic Acid and Rosmarinic Acid on Ultraviolet-B-Induced Cytokine/Chemokine Gene Expression in Skin Keratinocyte (HaCaT) Cells

Ultraviolet radiation (UV) induces an increase in multiple cutaneous inflammatory mediators. Ellagic acid (EA) and rosmarinic acid (RA) are natural anti-inflammatory and immunomodulatory compounds found in many plants, fruits, and nuts. We assessed the ability of EA and RA to modulate IL-1β, IL-6, IL-8, IL-10, MCP-1, and TNF-α gene expression in HaCaT cells after UVB irradiation. Cells were treated with UVB (100 mJ/cm(2)) and simultaneously with EA (5 μM in 0.1% DMSO) or RA (2.7 μM in 0.5% DMSO). Moreover, these substances were added to the UVB-irradiated cells 1 h or 6 h before harvesting, depending on the established UVB-induced cytokine expression peak. Cytokine gene expression was examined using quantitative real time polymerase chain reaction. RA produced a significant reduction in UVB-induced expression of IL-6, IL-8, MCP-1, and TNF-α when applied at the same time as irradiation. EA showed milder effects compared with RA, except for TNF-α. Both substances decreased IL-6 expression, also when applied 5 h after irradiation, and always produced a significant increase in UVB-induced IL-10 expression. Our findings suggest that EA and RA are able to prevent and/or limit the UVB-induced inflammatory cascade, through a reduction in proinflammatory mediators and the enhancement of IL-10, with its protective function

Occurrence of polychlorobiphenyls in buffalo mozzarella cheese from Campania (Italy)

Buffalo milk and mozzarella cheese produced in the Caserta and Salerno areas in Campania region have been investigated on the presence and the levels of polychlorobiphenyls (PCBs). Seven congeners, six non dioxin-like (NDL-PCBs nos. 28, 52, 101, 138, 153 and 180) and one dioxin-like (DL-PCB n. 118), were detected. PCBs were found at detectable levels in the 83% of the buffalo milk and in the 100% of the mozzarella cheese samples from Caserta; in those from Salerno the prevalence of contamination was 77% for milk and 73% for mozzarellas, respectively. The NDL-PCB content of mozzarellas collected in Caserta was significantly higher than that found in those from Salerno. The more diffuse congeners were PCB 28, 138 and 153 both in milk and in mozzarella cheese; PCB 118 contributed to the total PCB content for the 7% in milk and 2-3% in mozzarella cheese. On the basis of the Italian annual average consumption the contribution of mozzarella to the daily dietary intake of NDL-PCB can vary between 0.41 and 21.33 ng kg-1 bw, median value of 3.66 ng kg-1 bw. The levels of contamination in milk and dairies analyzed are similar or quite lower than those found in other European countries