Stochastic thermodynamics of a finite quantum system coupled to a heat bath

We consider a situation where an N-level system (NLS) is coupled to a heat bath without being necessarily thermalized. For this situation, we derive general Jarzynski-type equations and conclude that heat and entropy is flowing from the hot bath to the cold NLS and, vice versa, from the hot NLS to the cold bath. The Clausius relation between increase of entropy and transfer of heat divided by a suitable temperature assumes the form of two inequalities which have already been considered in the literature. Our approach is illustrated by an analytical example.

Quantum Photovoltaic Cells Driven by Photon Pulses

We investigate the quantum thermodynamics of two quantum systems, a two-level system and a four-level quantum photocell, each driven by photon pulses as a quantum heat engine. We set these systems to be in thermal contact only with a cold reservoir while the heat (energy) source, conventionally given from a hot thermal reservoir, is supplied by a sequence of photon pulses. The dynamics of each system is governed by a coherent interaction due to photon pulses in terms of the Jaynes-Cummings Hamiltonian together with the system-bath interaction described by the Lindblad master equation. We calculate the thermodynamic quantities for the two-level system and the quantum photocell including the change in system energy, the power delivered by photon pulses, the power output to an external load, the heat dissipated to a cold bath, and the entropy production. We thereby demonstrate how a quantum photocell in the cold bath can operate as a continuum quantum heat engine with a sequence of photon pulses continuously applied. We specifically introduce the power efficiency of the quantum photocell in terms of the ratio of output power delivered to an external load with current and voltage to the input power delivered by the photon pulse. Our study indicates a possibility that a quantum system driven by external fields can act as an efficient quantum heat engine under non-equilibrium thermodynamics.

IMPROVING THE QUALITY OF IMPREGNATION OF BIRCH WOOD IN THE PRODUCTION OF SLEEPERS

Wood is widely used for the production of sleepers in Russia. Sleepers made of natural wood have the disadvantage – short service life. It is possible to increase the service life of wooden sleepers using pressed (modified) wood for their manufacture. Wood pressing is one of the most promising areas for improving its physical and mechanical properties. Pressed wood, in its turn, has a drawback – the ability to significantly change size and shape when humidity changes, as well as low biological resistance. The solution to this problem is to impregnate wood with an antiseptic solution with a stabilizer. The durability of pressed wood products largely depends on the quality of its impregnation and the amount of absorbed solution by the surface layer. The most simple and effective method (among the known for impregnation in the manufacture of railway sleepers) is impregnation of wood in hot-cold baths. In the work, the efficiency of wood impregnation by the method of hot-cold baths has been studied taking into account various conditions of exposure to a cold solution. The first option is to quickly replace a hot solution with a cold one. The second is the impregnation of wood during the natural cooling of hot solution. It was found that the depth of wood impregnation during gradual cooling of wood in a hot solution is 2.5 times less than the depth of impregnation during cooling in a cold solution, both in the longitudinal and transverse directions. The amount of solution absorbed by wood when impregnated by the hot-cold bath method with the gradual cooling of hot impregnating solution is 16% less than when cooling in a cold impregnating solution. Hot-cold bath method with cooling in a cold solution can be recommended for the manufacture of sleepers from modified wood

Perception and Management of Fever in Children, by Mothers in Port Harcourt Nigeria

To determine mother’s perception and management of fever in their children. It was a descriptive cross-sectional study, carried out at the children outpatient clinic of the department of Paediatrics, University of Port Harcourt Teaching Hospital, over a one-year period, January to December, 2012. Every mother who presented with her child to the children outpatient clinic was recruited and interviewed using a structured questionnaire after obtaining written informed consent, as they presented their children to the children outpatient clinic of the University of Port Harcourt Teaching Hospital until we recruited 324mothers, whose children aged between 0-16 years into the study. A little over half of these mothers had completed secondary education. The thermometer was used by 209(64.50%) mothers and the preferred route was by mouth 135(41.67%). 175(54.01%) mothers reported temperature <35ºC as fever. 49.07% of the mothers were worried about the consequences of the fever. 43(13.3%) would give paracetamol. 24(7.4%) would tepid sponge. 15(4.6%) would give a cold bath. 6(1.9%) expose the child to air with reduced clothing. 4(1.2%), wrap the child with warm and thick cloth. 2(0.6%) gave antibiotics. 11 (3.4%) gave antimalaria. 6(1.9%) gave teething drugs. 1 (0.3%) gave nothing. Most mothers got their information on knowledge of fever management from doctors and nurses-164(50.62%). Paracetamol was the most commonly used drug by mothers for the treatment of fever at home-217 (67%). 87(26.852%) would take the child to hospital if fever persisted. This study found a significant association between using physical methods such as giving cold bath to reduce fever, and tepid sponging to reduce fever with no formal education P < 0.0001 and P< 0.0165 respectively. Data was analyzed using Epi-info version 7. Mothers awareness of fever in Port Harcourt is low and Paracetamol is commonly given to children with fever.

Ice Bath Therapy on Athletes Recovery Response Using EEG

Sport recovery system is an integral aspect to help athletes adapt faster to training. This is an important process of physical preparation by reducing fatigue where the athletes can ready for the next competition or training. However, most of an athlete doing training without having the fully recovery after the training and can affect their performance. The cold bath water immersion is the one of common technique to recover from the fatigue. In this study, Neurosky mindwave is use to extract the brain wave of an athlete to know the response of an athlete when perform the cold water immersion. The responses of an athlete include meditation which is in alpha wave that state in relax condition and beta wave that is in fatigue condition in sport. The raw brain wave signal that extract using Neurosky mindwave is analysed using Matlab in terms of time domain. After that, Fast Fourier Transform (FFT) will use to analysed in terms of frequency domain. This project used alpha and beta band to collect the data. The analysis have made based on the peak value in frequency domain to know the best time for cold water immersion and best cold bath temperature.