On the exploitability of thermo-charged capacitors

Recently [Physics Letters A, 374, (2010) 1801] the concept of vacuum capacitor spontaneously charged harnessing the heat from a single thermal reservoir at room temperature has been introduced, along with a mathematical description of its functioning and a discussion on the main paradoxical feature that seems to violate the Second Law of Thermodynamics. In the present paper we investigate the theoretical and practical possibility of exploiting a such thermo-charged capacitor as voltage/current generator: we show that if very weak provisos on the physical characteristics of the capacitor are fulfilled, then a non-zero current should flow across the device, allowing the generation of potentially usable voltage, current and electric power out of a single thermal source at room temperature. Preliminary results show that the power output is tiny but non-zero.Comment: 23 Pages, 10 Figures. Physica A 390/6 (2011) 482 + Addendum (2013

The Peculiar Status of the Second Law of Thermodynamics and the Quest for its Violation

Even though the second law of thermodynamics holds the supreme position among the laws of nature, as stated by many distinguished scientists, notably Eddington and Einstein, its position appears to be also quite peculiar. Given the atomic nature of matter, whose behaviour is well described by statistical physics, the second law could not hold unconditionally, but only statistically. It is not an absolute law. As a result of this, in the present paper we try to argue that we have not yet any truly cogent argument (known fundamental physical laws) to exclude its possible macroscopic violation. Even Landauer's information-theoretic principle seems to fall short of the initial expectations of being the fundamental `physical' reason of all Maxwell's demons failure. Here we propose a modified Szilard engine which operates without any steps in the process resembling the creation or destruction of information. We argue that the information-based exorcisms must be wrong, or at the very least superfluous, and that the real physical reason why such engines cannot work lies in the ubiquity of thermal fluctuations (and friction). We see in the above peculiar features the main motivation and rationale for pursuing exploratory research to challenge the second law, which is still ongoing and probably richer than ever. A quite thorough (and critical) description of some of these challenges is also given.Comment: 25 pages, 8 figures; Studies in History and Philosophy of Modern Physics, to appear. arXiv admin note: text overlap with arXiv:1011.395

Exciton scattering in light-harvesting systems of purple bacteria

Using the reduced density matrix formalism the exciton scattering in light-harvesting systems of purple bacteria is calculated. The static disorder (fluctuations of the site energies) as well as the dynamic disorder (dissipation) is taken into account in this work. Circular aggregates with 18 pigments are studied to model the B850 ring of bacteriochlorophylls with LH2 complexes. It can be shown that the influence of dissipation may not be neglected in the simulation of the time-dependent anisotropy of fluorescence. Also an elliptical deformation of the ring could be essential

Influence of Static and Dynamic Disorder on the Anisotropy of Emission in the Ring Antenna Subunits of Purple Bacteria Photosynthetic Systems

Using the reduced density matrix formalism the time dependence of the exciton scattering in light-harvesting ring systems of purple bacteria is calculated. In contrast to the work of Kumble and Hochstrasser (J. Chem. Phys. 109 (1998) 855) static disorder (fluctuations of the site energies) as well as dynamic disorder (dissipation) is taken into account. For the description of dissipation we use Redfield theory in exciton eigenstates without secular approximation. This is shown to be equivalent to the Markovian limit of Capek's theory in local states. Circular aggregates with 18 pigments are studied to model the B850 ring of bacteriochlorophyls within LH2 complexes. It can be demonstrated that the dissipation is important for the time-dependent anisotropy of the fluorescence. Smaller values of static disorder are sufficient to produce the same decay rates in the anisotropy in comparison with the results by Kumble and Hochstrasser

Thermalisation by a boson bath in a pure state

We consider a quantum system weakly coupled to a large heat bath of harmonic oscillators. It is well known that such a boson bath initially at thermal equilibrium thermalises the system. We show that assuming a priori an equilibrium state is not necessary to obtain the thermalisation of the system. We determine the complete Schr\"odinger time evolution of the subsystem of interest for an initial pure product state of the composite system consisting of the considered system and the bath. We find that the system relaxes into canonical equilibrium for almost all initial pure bath states of macroscopically well-defined energy. The temperature of the system asymptotic thermal state is determined by the energy of the initial bath state as the corresponding microcanonical temperature. Moreover, the time evolution of the system is identical to the one obtained assuming that the boson bath is initially at thermal equilibrium with this temperature. A significant part of our approach is applicable to other baths and we identify the bath features which are requisite for the thermalisation studied

The issue of groin injuries and risk factors affecting this type of injuries among football players.

Název práce Problematika poranění třísel a ovlivnění rizikových faktorů tohoto zranění u fotbalistů. Cíl práce Hlavní cíl této diplomové práce je shrnutí teoretických poznatků týkající se poranění v oblasti třísla u fotbalistů a ověření účinnosti preventivního programu pro snížení výskytu zranění v oblasti třísel u těchto hráčů fotbalu. Metody řešení Teoretická část se zabývá danou problematikou na úrovni literární rešerše české a zejména zahraniční literatury. Poznatky teoretické části byly čerpány zejména ze zahraničních odborných periodik, monografií a elektronických databází, převážně PubMed a PEDro. V druhé experimentální části byl aplikován preventivní program. Experimentu se zúčastnili hráči fotbalu (n=42) věkové kategorie U16 (n=20) a U17 (n=22). Vybraná skupina probandů prováděla preventivní intervenci 1x týdně po dobu 6 měsíců. Následně byly výsledky sledovaného zranění porovnány se stejným obdobím v předchozím roce, kdy se hráči nevěnovali žádným preventivním opatřením. Informace o předchozích zraněních byly získány nestandardizovaným dotazníkovým šetřením. Výsledky Na základě literární rešerše je předchozí zranění považováno za nejvýznamnější rizikový faktor pro vznik nového zranění v oblasti třísla. Mezi další významné rizikové faktory patří předčasný návrat do tréninkového procesu či...Title The issue of groin injuries and risk factors affecting this type of injuries among football players. Objectives The main objective of this thesis is to summarize theoretical findings regarding the groin injuries among soccer players and to prove efficiency of preventive training program aimed at reduction of groin injuries incidence in soccer players. Methods The theoretical part deals with the given issue as a research and theoretical overview of the current findings, based on Czech and especially foreign literature. Findings of theoretical part were obtained by foreign periodicals, monographies and electronic database, mostly PubMed and PEDro. In the second part of thesis a preventive training program was applied at a specific group of soccer players (n=42) in age U16 (n=20) and U17 (n=22). Selected group of probands performed preventive intervention training once a week for 6 months. After that results were compared with the same time of season in the previous year, when no preventive measures had been taken. Information about previous injury has been obtained by non-standardized questionnaire. Results Based on the literature review previous injury is considered to be the most significant risk factor for new injury in groin. Other significant risk factors include untimely return to...FyzioterapieFakulta tělesné výchovy a sportuFaculty of Physical Education and Spor

The issue of groin injuries and risk factors affecting this type of injuries among football players.

Název práce . Cíl práce Hlavní cíl této diplomové práce je shrnutí týkající se v vního programu pro snížení výsky fotbalu. Metod slouží jako podklad k v . monografií a elektronických databází, PubMed a PEDro. V druhé . Experimentu se fotbalu (n=42) (n=20) a U17 (n=22). y výsledky porovnány se stejným obdobím v , kdy získány nestandardizo . Výsledky nejvýznamn v . Mezi další rehabilitace. zaznamenáno na . byl faul. dvaceti v oblast celkového bylo hlášeno dvacet á 20 %. :Title The issue of groin injuries and risk factors affecting this type of injuries among football players. Objectives The main objective of this thesis is to summarize theoretical findings regarding the groin injuries among soccer players and to prove efficiency of preventive training program aimed at reduction of groin injuries incidence in soccer players. Methods The theoretical part deals with the given issue as a research and theoretical overview of the current findings, based on Czech and especially foreign literature. Findings of theoretical part were obtained by foreign periodicals, monographies and electronic database, mostly PubMed and PEDro. In the second part of thesis a preventive training program was applied at a specific group of soccer players (n=42) in age U16 (n=20) and U17 (n=22). Selected group of probands performed preventive intervention training once a week for 6 months. After that results were compared with the same time of season in the previous year, when no preventive measures had been taken. Information about previous injury has been obtained by non-standardized questionnaire. Results Based on the theoretical overview previous injury is considered to be the most significant risk factor for new injury in groin. Other significant risk factors include untimely return to...FyzioterapieFakulta tělesné výchovy a sportuFaculty of Physical Education and Spor

A Note on Solid-State Maxwell Demon

Starting from 2002, at least two kinds of laboratory-testable, solid-state Maxwell demons have been proposed that utilize the electric field energy of an open-gap n-p junction and that seem to challenge the validity of the Second Law of Thermodynamics. In the present paper we present some arguments against the alleged functioning of such devices.Comment: 9 pages, 4 figures. Foundations of Physics, forthcoming. arXiv admin note: substantial text overlap with arXiv:1101.505

Global and local relaxation of a spin-chain under exact Schroedinger and master-equation dynamics

We solve the Schroedinger equation for an interacting spin-chain locally coupled to a quantum environment with a specific degeneracy structure. The reduced dynamics of the whole spin-chain as well as of single spins is analyzed. We show, that the total spin-chain relaxes to a thermal equilibrium state independently of the internal interaction strength. In contrast, the asymptotic states of each individual spin are thermal for weak but non-thermal for stronger spin-spin coupling. The transition between both scenarios is found for couplings of the order of $0.1 \times \Delta E$, with $\Delta E$ denoting the Zeeman-splitting. We compare these results with a master equation treatment; when time averaged, both approaches lead to the same asymptotic state and finally with analytical results.Comment: RevTeX, 8 pages, 14 figures, added DOI and forgotten reference

Electronic Coherence Dephasing in Excitonic Molecular Complexes: Role of Markov and Secular Approximations

We compare four different types of equations of motion for reduced density matrix of a system of molecular excitons interacting with thermodynamic bath. All four equations are of second order in the linear system-bath interaction Hamiltonian, with different approximations applied in their derivation. In particular we compare time-nonlocal equations obtained from so-called Nakajima-Zwanzig identity and the time-local equations resulting from the partial ordering prescription of the cummulant expansion. In each of these equations we alternatively apply secular approximation to decouple population and coherence dynamics from each other. We focus on the dynamics of intraband electronic coherences of the excitonic system which can be traced by coherent two-dimensional spectroscopy. We discuss the applicability of the four relaxation theories to simulations of population and coherence dynamics, and identify features of the two-dimensional coherent spectrum that allow us to distinguish time-nonlocal effects.Comment: 14 pages, 8 figure