Farey sequence in the appearance of subharmonic Shapiro steps

Largest Lyapunov exponent has been examined in the dynamical-mode locking phenomena of the ac+dc driven dissipative Frenkel-Kontorova model with deformable substrate potential. Due to deformation, large fractional and higher order subharmonic steps appear in the response function of the system. Computation of the largest Lyapunov exponent as a way to verify their presence led to the observation of the Farey sequence. In the standard regime, between the large harmonic steps, the appearance of halfinteger and subharmonic steps, and their relative sizes follow the Farey construction. In the nonstandard regime, though halfinteger steps are larger than harmonic ones, Farey construction is still present in the appearance of higher order subharmonic steps. The examination of Lyapunov exponents also shows that there is no chaos in the system.Comment: 7 pages, 9 figure

Forestry and traditional woodland management in North Dalmatia c. 1790 to 1990: an environmental history

This thesis focuses on traditional management and forestry in coastal areas of northern Dalmatia in Croatia. It considers the time period from the dissolution of Republic of Venice until the end of SFR Yugoslavia in 1990. It is based on archival records on forestry activities, Austrian land surveys from the 1820s, oral histories in three case studies, aerial photographs and analysis of articles and discussions published in the Forestry Journal since 1877. The thesis is structured chronologically, and woodland use, policies and management are considered in the context of different administrations – the French (1805-1815), Austrian (1815-1918), first Yugoslav (1920-1941) and second Yugoslav (1945-1990). Although today they are neglected and considered unproductive, the research emphasises that traditional woodlands and wooded landscapes had a major role in the local livelihoods in the study area. It explores the ways these woodlands were used by local people and how they were shaped by woodland regulation and management which were characterised by strong continuity over the last two centuries. It also investigates how reforestation, the most important forestry policy in Dalmatia, developed in the late 19th century and its implications for land use and tourism

Application of largest Lyapunov exponent analysis on the studies of dynamics under external forces

Dynamics of driven dissipative Frenkel-Kontorova model is examined by using largest Lyapunov exponent computational technique. Obtained results show that besides the usual way where behavior of the system in the presence of external forces is studied by analyzing its dynamical response function, the largest Lyapunov exponent analysis can represent a very convenient tool to examine system dynamics. In the dc driven systems, the critical depinning force for particular structure could be estimated by computing the largest Lyapunov exponent. In the dc+ac driven systems, if the substrate potential is the standard sinusoidal one, calculation of the largest Lyapunov exponent offers a more sensitive way to detect the presence of Shapiro steps. When the amplitude of the ac force is varied the behavior of the largest Lyapunov exponent in the pinned regime completely reflects the behavior of Shapiro steps and the critical depinning force, in particular, it represents the mirror image of the amplitude dependence of critical depinning force. This points out an advantage of this technique since by calculating the largest Lyapunov exponent in the pinned regime we can get an insight into the dynamics of the system when driving forces are applied.Comment: 10 pages, 8 figure

Forestry and traditional woodland management in North Dalmatia c. 1790 to 1990: an environmental history

This thesis focuses on traditional management and forestry in coastal areas of northern Dalmatia in Croatia. It considers the time period from the dissolution of Republic of Venice until the end of SFR Yugoslavia in 1990. It is based on archival records on forestry activities, Austrian land surveys from the 1820s, oral histories in three case studies, aerial photographs and analysis of articles and discussions published in the Forestry Journal since 1877. The thesis is structured chronologically, and woodland use, policies and management are considered in the context of different administrations – the French (1805-1815), Austrian (1815-1918), first Yugoslav (1920-1941) and second Yugoslav (1945-1990). Although today they are neglected and considered unproductive, the research emphasises that traditional woodlands and wooded landscapes had a major role in the local livelihoods in the study area. It explores the ways these woodlands were used by local people and how they were shaped by woodland regulation and management which were characterised by strong continuity over the last two centuries. It also investigates how reforestation, the most important forestry policy in Dalmatia, developed in the late 19th century and its implications for land use and tourism

Sacred groves: an insight into Dalmatian forest history

The French administration in Dalmatia (1805-1813) was short but is often praised by foresters as advanced in terms of woodland management because of their establishment of so-called sacred groves or sacri boschi. Based on archival sources and19thcentury maps, this research explores the establishment and demise of sacred groves and places them within the broader forest history of Dalmatia. It reveals that the literal translation of the term sacro boscoas sacred grove (sveti gaj) by 19th century foresters was not precise which caused misrepresentation and misunderstandings of what sacro bosco actually meant. The more appropriate translation would be forbidden groves (zabranjen gaj)as this also reflects the nature of these woodlands, which were in fact woodland sections where exploitation was prohibited. Establishment of forbidden groves was not a French invention since the practice was widely used before the French and during the Austrian Empire (1814-1918). In the second half of the 19th century and with the change of official language, the Italian term sacro bosco was replaced with the Croatian term protected area (branjevina)

Complexity of Shapiro steps

We demonstrate on the example of the dc+ac driven overdamped Frenkel-Kontorova model that an easily calculable measure of complexity can be used for the examination of Shapiro steps in presence of thermal noise. In real systems, thermal noise causes melting or even disappearance of Shapiro steps, which makes their analysis in the standard way from the response function difficult. Unlike in the conventional approach, here, by calculating the Kolmogorov complexity of certain areas in the response function we were able to detect Shapiro steps, measure their size with desired precision and examine their temperature dependence. The aim of this work is to provide scientists, particularly experimentalists, an unconventional but a practical and easy tool for examination of Shapiro steps in real systems.Comment: 6 pages, 5 figures, References and text edite

Comparing patient experience survey scores between telehealth and in-person ambulatory pediatric subspecialty visits

To determine the effect of encounter methods on patient experience, we evaluated patient experience survey data comparing scores between telehealth and in-person visits and pre-COVID-19 and COVID-19 time periods. Pediatric subspecialty visits were either in-person or via telehealth and received the same 16-question patient experience survey. Top box (5/5) scores were compared between in-person and telehealth visits for pre-COVID-19 and COVID-19 periods as well as between periods for in-person and telehealth visits. In addition, for both time periods and encounter methods, correlation analysis was performed to evaluate best correlation between likelihood to recommend practice and the 15 other survey questions. Comparing the COVID-19 period data, there was a statistically significant difference in the top box likelihood to recommend practice score comparing in-person to telehealth numbers (81.01% vs 87.13%, p = 0.0003). Comparing pre-COVID-19 with COVID-19, this was not true for in-person scores (79.97% vs 81.01%, p = 0.4060) or telehealth scores (82.50% vs 87.13%, p = 0.2084). The question with the highest correlation coefficient to likelihood to recommend practice was how well staff worked together in both time periods and visit methods. We conclude that Likelihood to recommend experience scores were statistically significantly higher for telehealth as compared to in-person pediatric subspecialty ambulatory visits during the COVID-19 pandemic. There were no such differences in likelihood to recommend comparing pre- vs COVID-19 time periods for either in-person or telehealth visits so the change in scoring seems to be related to the mode of care delivery. Experience Framework This article is associated with the Policy & Measurement lens of The Beryl Institute Experience Framework. (https://www.theberylinstitute.org/ExperienceFramework). Access other PXJ articles related to this lens. Access other resources related to this lens

Two-vibron bound states in alpha-helix proteins : the interplay between the intramolecular anharmonicity and the strong vibron-phonon coupling

The influence of the intramolecular anharmonicity and the strong vibron-phonon coupling on the two-vibron dynamics in an $\alpha$-helix protein is studied within a modified Davydov model. The intramolecular anharmonicity of each amide-I vibration is considered and the vibron dynamics is described according to the small polaron approach. A unitary transformation is performed to remove the intramolecular anharmonicity and a modified Lang-Firsov transformation is applied to renormalize the vibron-phonon interaction. Then, a mean field procedure is realized to obtain the dressed anharmonic vibron Hamiltonian. It is shown that the anharmonicity modifies the vibron-phonon interaction which results in an enhancement of the dressing effect. In addition, both the anharmonicity and the dressing favor the occurrence of two different bound states which the properties strongly depend on the interplay between the anharmonicity and the dressing. Such a dependence was summarized in a phase diagram which characterizes the number and the nature of the bound states as a function of the relevant parameters of the problem. For a significant anharmonicity, the low frequency bound states describe two vibrons trapped onto the same amide-I vibration whereas the high frequency bound states refer to the trapping of the two vibrons onto nearest neighbor amide-I vibrations.Comment: may 2003 submitted to Phys. Rev.

From Davydov solitons to decoherence-free subspaces: self-consistent propagation of coherent-product states

The self-consistent propagation of generalized $D_{1}$ [coherent-product] states and of a class of gaussian density matrix generalizations is examined, at both zero and finite-temperature, for arbitrary interactions between the localized lattice (electronic or vibronic) excitations and the phonon modes. It is shown that in all legitimate cases, the evolution of $D_{1}$ states reduces to the disentangled evolution of the component $D_{2}$ states. The self-consistency conditions for the latter amount to conditions for decoherence-free propagation, which complement the $D_{2}$ Davydov soliton equations in such a way as to lift the nonlinearity of the evolution for the on-site degrees of freedom. Although it cannot support Davydov solitons, the coherent-product ansatz does provide a wide class of exact density-matrix solutions for the joint evolution of the lattice and phonon bath in compatible systems. Included are solutions for initial states given as a product of a [largely arbitrary] lattice state and a thermal equilibrium state of the phonons. It is also shown that external pumping can produce self-consistent Frohlich-like effects. A few sample cases of coherent, albeit not solitonic, propagation are briefly discussed.Comment: revtex3, latex2e; 22 pages, no figs.; to appear in Phys.Rev.E (Nov.2001