Quantum thermodynamic Carnot and Otto-like cycles for a two-level system

From the thermodynamic equilibrium properties of a two-level system with variable energy-level gap $\Delta$, and a careful distinction between the Gibbs relation $dE = T dS + (E/\Delta) d\Delta$ and the energy balance equation $dE = \delta Q^\leftarrow - \delta W^\to$, we infer some important aspects of the second law of thermodynamics and, contrary to a recent suggestion based on the analysis of an Otto-like thermodynamic cycle between two values of $\Delta$ of a spin-1/2 system, we show that a quantum thermodynamic Carnot cycle, with the celebrated optimal efficiency $1 - (T_{low}/T_{high})$, is possible in principle with no need of an infinite number of infinitesimal processes, provided we cycle smoothly over at least three (in general four) values of $\Delta$, and we change $\Delta$ not only along the isoentropics, but also along the isotherms, e.g., by use of the recently suggested maser-laser tandem technique. We derive general bounds to the net-work to high-temperature-heat ratio for a Carnot cycle and for the 'inscribed' Otto-like cycle, and represent these cycles on useful thermodynamic diagrams.Comment: RevTex4, 4 pages, 1 figur

Thermodynamic analysis of turbulent combustion in a spark ignition engine. Experimental evidence

A method independent of physical modeling assumptions is presented to analyze high speed flame photography and cylinder pressure measurements from a transparent piston spark ignition research engine. The method involves defining characteristic quantities of the phenomena of flame propagation and combustion, and estimating their values from the experimental information. Using only the pressure information, the mass fraction curves are examined. An empirical burning law is presented which simulates such curves. Statistical data for the characteristics delay and burning angles which show that cycle to cycle fractional variations are of the same order of magnitude for both angles are discussed. The enflamed and burnt mass fractions are compared as are the rates of entrainment and burning

Combustion and operating characteristics of spark-ignition engines

The spark-ignition engine turbulent flame propagation process was investigated. Then, using a spark-ignition engine cycle simulation and combustion model, the impact of turbocharging and heat transfer variations or engine power, efficiency, and NO sub x emissions was examined

A nonlinear model dynamics for closed-system, constrained, maximal-entropy-generation relaxation by energy redistribution

We discuss a nonlinear model for the relaxation by energy redistribution within an isolated, closed system composed of non-interacting identical particles with energy levels e_i with i=1,2,...,N. The time-dependent occupation probabilities p_i(t) are assumed to obey the nonlinear rate equations tau dp_i/dt=-p_i ln p_i+ alpha(t)p_i-beta(t)e_ip_i where alpha(t) and beta(t) are functionals of the p_i(t)'s that maintain invariant the mean energy E=sum_i e_ip_i(t) and the normalization condition 1=sum_i p_i(t). The entropy S(t)=-k sum_i p_i(t) ln p_i(t) is a non-decreasing function of time until the initially nonzero occupation probabilities reach a Boltzmann-like canonical distribution over the occupied energy eigenstates. Initially zero occupation probabilities, instead, remain zero at all times. The solutions p_i(t) of the rate equations are unique and well-defined for arbitrary initial conditions p_i(0) and for all times. Existence and uniqueness both forward and backward in time allows the reconstruction of the primordial lowest entropy state. The time evolution is at all times along the local direction of steepest entropy ascent or, equivalently, of maximal entropy generation. These rate equations have the same mathematical structure and basic features of the nonlinear dynamical equation proposed in a series of papers ended with G.P.Beretta, Found.Phys., 17, 365 (1987) and recently rediscovered in S. Gheorghiu-Svirschevski, Phys.Rev.A, 63, 022105 and 054102 (2001). Numerical results illustrate the features of the dynamics and the differences with the rate equations recently considered for the same problem in M.Lemanska and Z.Jaeger, Physica D, 170, 72 (2002).Comment: 11 pages, 7 eps figures (psfrag use removed), uses subeqn, minor revisions, accepted for Physical Review

Evaluation of Breaking Force of Different Suture Materials Used in Dentistry: An In Vitro Mechanical Comparison

The success of surgical procedures is strictly related to the biomechanical properties of the suture. Mechanical comparisons are scarcely reported in the literature, so the purpose of the present study was to evaluate and compare the mechanical behavior of different sutures commonly used in oral surgery in terms of traction resistance. Sutures made of eight different materials were analyzed: silk (S), polyglycolide-co-caprolactone (PGCL), polypropylene (PP), rapid polyglycolide (rPGA), standard polyglycolide (PGA), polyamide (PA), polyester (PE), and polyvinylidene fluoride (PVDF). For each material, three different sizes were tested: 3-0, 4-0, and 5-0. The breaking force of each suture was assessed with a uniaxial testing machine after being immersed in artificial saliva at 37\u25e6 C. The outcomes analyzed were the breaking force, the needle\u2013thread detachment breaking-point and the node response after forward\u2013reverse\u2013forward (FRF) tying when subjected to a tensile force. The 3-0 rPGA provided the maximum resistance, while the lowest value was recorded for the 5-0 PGCL. In general, 3-0 and 4-0 gauges showed non-statistically significant differences in terms of needle\u2013thread detachment. The highest needle\u2013thread detachment was found for the 3-0 PGA, whereas the lowest value was observed for the 5-0 PGCL. After tying the knot with an FRF configuration, the thread that showed the highest resistance to tension was the 3/0 silk, while the thread with the lowest resistance was the 5/0 silk. These data should be considered so that the operator is aware of as many aspects as possible on the behavior of various materials to ensure successful healing

Use Of Molecular Epidemiology To Monitor The Nosocomial Dissemination Of Methicillin-resistant Staphylococcus Aureus Un A University Hospital From 1991 To 2001

Methicillin-resistant Staphylococcus aureus (MRSA) has been the cause of major outbreaks and epidemics among hospitalized patients, with high mortality and morbidity rates. We studied the genomic diversity of MRSA strains isolated from patients with nosocomial infection in a University Hospital from 1991 to 2001. The study consisted of two periods: period I, from 1991 to 1993 and period II from 1995 to 2001. DNA was typed by pulsed-field gel electrophoresis and the similarity among the MRSA strains was determined by cluster analysis. During period 1, 73 strains presented five distinctive DNA profiles: A, B, C, D, and E. Profile A was the most frequent DNA pattern and was identified in 55 (75.3%) strains; three closely related and four possibly related profiles were also identified. During period II, 80 (68.8%) of 117 strains showed the same endemic profile A identified during period I, 18 (13.7%) closely related profiles and 18 (13.7%) possibly related profiles and, only one strain presented an unrelated profile. Cluster analysis showed a 96% coefficient of similarity between profile A from period I and profile A from period II, which were considered to be from the same clone. The molecular monitoring of MRSA strains permitted the determination of the clonal dissemination and the maintenance of a dominant endemic strain during a 10-year period and the presence of closely and possibly related patterns for endemic profile A. However, further studies are necessary to improve the understanding of the dissemination of the endemic profile in this hospital.37913451351Fluckiger, U., Widmer, A.F., Epidemiology of methicillin-resistant Staphylococcus aureus (1999) Chemotherapy, 45, pp. 121-134Deplano, A., Schuermans, A., Van Eldere, J., Multicenter evaluation of epidemiological typing of methicillin-resistant Staphylococcus aureus strains by repetitive-element PCR analysis (2000) Journal of Clinical Microbiology, 38, pp. 3527-3533Stranden, A., Frei, R., Widmer, A.F., Molecular typing of methicillin-resistant Staphylococcus aureus: Can PCR replace pulsed-field gel electrophoresis? (2003) Journal of Clinical Microbiology, 41, pp. 3181-3186Wang, J.T., Chen-Chun, Y., Yang, T.L., Chang, C.S., Molecular epidemiology and antimicrobial susceptibility of methicillin-resistant Staphylococcus, aureus in Taiwan (2002) Diagnostic Microbiology and Infectious Disease, 42, pp. 199-203Tambic, A., Power, E.G.M., Talsania, H., Anthony, R.M., French, G.L., Analysis of an outbreak of non phage-typeable methicillin-resistant Staphylococcus aureus by using a randomly amplified polymorphic DNA assay (1997) Journal of Clinical Microbiology, 35, pp. 3092-3097Conterno, L.O., Wey, S.B., Castello, A., Risk factors for mortality in Staphylococcus aureus bacteremia (1998) Infection Control and Hospital Epidemiology, 19, pp. 32-37Pujol, M., Penã, C., Pallares, R., Ayats, J., Arisa, J., Gudiol, F., Risk factors for nosocomial bacteremia due to methicillin-resistant Staphylococcus aureus (1996) European Journal of Clinical Microbiology and Infectious Diseases, 13, pp. 96-102Archer, G.L., Niemeyer, D.M., Origin and evolution of DNA associated with resistance to methicillin in Staphylococci (1998) Trends in Microbiology, 2, pp. 343-347Witte, W., Kresken, M., Braulke, C., Cuny, C., Increasing incidence and widespread dissemination of methicillin-resistant Staphylococcus aureus (MRSA) in hospitals in central Europe, with special reference to German hospitals (1997) Clinical Microbiology and Infection, 3, pp. 414-422Corso, A., Santos, S.I., Aires de Souza, M., Rossi, A., Lencastre, H., Spread of a methicillin-resistant and multiresistant epidemic clone of Staphylococcus aureus (1998) Journal of Medical Microbiology, 4, pp. 179-184Alfizah, H., Norazah, A., Nordiah, A.J., Lim, V.K., DNA fingerprinting of methicillin-resistant Staphylococcus aureus (MRSA) by pulsed-field gel electrophoresis (PFGE) in a teaching hospital in Malaysia (2002) Medical Journal of Malaysia, 57, pp. 319-328Sola, C., Gribaudo, G., Vindel, A., Patrito, L., Bocco, J.L., Identification of a novel methicillin-resistant Staphylococcus aureus epidemic clone in Cordoba, Argentina, involved in nosocomial infections (2002) Journal of Clinical Microbiology, 40, pp. 1427-1435Melter, O., Aires de Sousa, M., Urbaskova, P., Jakubu, V., Zemlickova, H., Lencastre, H., Update on the major clonal types of methicillin-resistant Staphylococcus aureus in the Czech Republic (2003) Journal of Clinical Microbiology, 41, pp. 4998-5005Sader, H.S., Pignatari, A.C., Hollis, R.J., Jones, R.N., Evaluation of inter-hospital spread of methicillin-resistant Staphylococcus aureus in São Paulo using pulsed-field gel electrophoresis of chromosomal DNA (1994) Infection Control and Hospital Epidemiology, 15, pp. 320-323Santos, F.L., Sader, H., Bortolotto, V.I., Gontijo, F.P.P., Pignatari, A.C., Analysis of the clonal diversity of Staphylococcus aureus methicillin-resistant strains isolated at João Pessoa, State of Paraíba, Brazil (1996) Memórias Do Instituto Oswaldo Cruz, 91, pp. 101-105Moretti-Branchini, M.L., Aplicação de métodos de tipagem molecular na investigação de surtos intra-hospitalares (1998), Livre-docência thesis, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, BrazilPottinger, J.M., Herwaldt, L.A., Peri, T.M., Basics of surveillance: An overview (1999) Infection Control and Hospital Epidemiology, 18, pp. 513-527Loureiro, B.A., De Moraes, B.A., Quadra, M.R.R., Pinheiro, G.S., Suffys, P.N., Asensi, M.D., Molecular epidemiology of methicillin resistant Staphylococcus aureus isolated from newborns in a hospital in Rio de Janeiro, Brazil (2000) Memórias Do Instituto Oswaldo Cruz, 95, pp. 777-782Blanc, D.S., Struelens, M.J., Deplano, A., Hauser, P.M., Petgnat, C., Franioli, P., Epidemiological validation of pulsed-field gel electrophoresis patterns for methicillin-resistant Staphylococcus aureus (2001) Journal of Clinical Microbiology, 39, pp. 3442-3445Tenover, F.C., Gaynes, R.P., The epidemiology of Staphylococcus infection (2000) Gram-Positive Pathogens, , Fischetti VA, Novick RP, Ferretti JJ, Portnoy DA & Rood JL (Editors), American Society for Microbiology, Washington, DC, USASchmitz, F.J.M., Steiert, H.V., Tichy, B., Hofmann, J., Verhoef, H.P., Heinz, K., Köhrer, T., Jones, M.E., Typing of methicillin-resistant Staphylococcus aureus isolates from Düsseldorf by six genotypic methods (1998) Journal of Clinical Microbiology, 47, pp. 341-351Montesianos, I., Salido, E., Delgado, T., Cuervo, M., Sierra, A., Epidemiologic genotyping of methicillin-resistant Staphylococcus aureus by pulsed-field gel electrophoresis at a university hospital and comparison with antibiotyping and protein A and coagulase gene polymorphisms (2002) Journal of Clinical Microbiology, 40, pp. 921-925Tenover, F.C., Arbeit, R.D., Goering, R.V., Mickelsen, P.A., Murray, B.E., Persing, D.H., Swaminathan, B., Interpreting chromosomal DNA restriction patterns produced by pulsed-field gel electrophoresis: Criteria for bacterial strain typing (1995) Journal of Clinical Microbiology, 33, pp. 2233-2239Barbier, N., Saulnier, P., Chachaty, E., Dumontier, S., Remont, A., Random amplified polymorphic DNA typing versus pulsed-field gel electrophoresis for epidemiological typing of vancomycin-resistant enterococci (1996) Journal of Clinical Microbiology, 34, pp. 1096-1099Olive, M., Bean, P., Principles and application of methods for DNA-based typing of microbial organisms (1995) Journal of Clinical Microbiology, 37, pp. 1661-1669Fujino, T., Sekiguchi, J.I., Kawana, A., Molecular epidemiology of methicillin-resistant Staphylococcus aureus in a Tokyo hospital in 2002 (2003) Journal of Infectious Diseases, 55, pp. 210-213Tenover, F.C., Arbeit, R.D., Goering, R.V., How to select and interpret molecular strain typing methods for epidemiological studies of bacterial infections: A review for healthcare epidemiologists (1997) Infection Control and Hospital Epidemiology, 18, pp. 426-439Garner, J.S., Jarvis, W., Emori, T.G., Horan, T.C., Hughes, J.M., CDC definitions for nosocomial infections (1988) American Journal of Infection Control, 16, pp. 128-140Bauer, A.W., Kirby, W.M.M., Sherris, J.C., Turck, M., Antibiotic susceptibility testing by a standardized single disk method (1996) American Journal of Clinical Pathology, 45, pp. 493-496(1999) Performance Standards for Antimicrobial Susceptibility Testing, , National Committee for Clinical Laboratory Standards (NCCLS) Ninth Informational Supplement M100-S9Aires De Sousa, M., Crisostomo, M.I., Santos Sanches, I., Wu, J.S., Fuzhong, J., Tomasz, A., De Lencastre, H., Frequent recovery of a single clonal type of multidrug-resistant Staphylococcus aureus from patients in two hospitals in Taiwan and China (2003) Journal of Clinical Microbiology, 41, pp. 159-163Teixeira, L., Resende, C.A., Ormonde, L.R., Rosenbaum, R., Figueiredo, A.M.S., Lencastre, H., Tomasz, A., Geographic spread of epidemic multiresistant Staphylococcus aureus clone in Brazil (1995) Journal of Clinical Microbiology, 33, pp. 2400-2404Tambic, A., Power, E.G.M., Tambic, T., Snur, I., French, G.L., Epidemiological analysis of methicillin-resistant Staphylococcus aureus in a Zagreb trauma hospital using a randomly amplified polymorphic DNA-typing method (1999) European Journal of Clinical Microbiology and Infectious Diseases, 18, pp. 335-340Miragaia, M., Couto, I., Pereira Sandro, F.F., Molecular characterization of methicillin-resistant Staphylococcus epidermidis: Evidence of geographic dissemination (2002) (2003) Journal of Clinical Microbiology, 40, pp. 430-438Boyce, J.M., Treatment and control of colonization in the prevention of nosocomial infections (1996) Infection Control and Hospital Epidemiology, 17, pp. 256-261Salmenlinna, S., Vuopio-Varkila, J., Recognition of two groups of methicillin-resistant Staphylococcus aureus strains based on epidemiology, antimicrobial susceptibility, hypervariable-region type, and ribotype in Finland (2001) Journal of Clinical Microbiology, 39, pp. 2243-2247El-Din, S.A.S., El-Shafey, E.I., Mohamad, B., El-Hadidy, M.R., El-Din, A.B., El-Hadidy, M.M., Zaghloul, H.A., Methicillin-resistant Staphylococcus, aureus: A problem in the burns unit (2003) Egyptian Journal of Plastic and Reconstructive Surgery, 27, pp. 1-10Walker, J., Borrow, R., Goering, R.V., Egerton, S., Fox, A., Oppenhein, B.A., Subtyping of methicillin-resistant Staphylococcus aureus isolates from the North-West of England: A comparison of standardized pulsed-field gel electrophoresis with bacteriophage typing including an inter-laboratory reproducibility study (1999) Journal of Medical Microbiology, 48, pp. 297-301Waller, T.M.A., Methicillin-resistant Staphylococcus aureus typing methods: Which should be international standard? (2000) Journal of Hospital Infection, 44, pp. 160-172McDougal, L.K., Steward, C.D., Killgore, G.E., Chaitram, J.M., McAllister, S.K., Tenover, F.C., Pulsed-field gel electrophoresis typing of oxacillin-resistant Staphylococcus aureus isolates from the United States: Establishing a national database (2003) Journal of Clinical Microbiology, 41, pp. 5113-512

The smallest refrigerators can reach maximal efficiency

We investigate whether size imposes a fundamental constraint on the efficiency of small thermal machines. We analyse in detail a model of a small self-contained refrigerator consisting of three qubits. We show analytically that this system can reach the Carnot efficiency, thus demonstrating that there exists no complementarity between size and efficiency.Comment: 9 pages, 1 figure. v2: published versio

Use Of Molecular Epidemiology To Monitor The Nosocomial Dissemination Of Methicillin-resistant Staphylococcus Aureus In A University Hospital From 1991 To 2001.

Methicillin-resistant Staphylococcus aureus (MRSA) has been the cause of major outbreaks and epidemics among hospitalized patients, with high mortality and morbidity rates. We studied the genomic diversity of MRSA strains isolated from patients with nosocomial infection in a University Hospital from 1991 to 2001. The study consisted of two periods: period I, from 1991 to 1993 and period II from 1995 to 2001. DNA was typed by pulsed-field gel electrophoresis and the similarity among the MRSA strains was determined by cluster analysis. During period I, 73 strains presented five distinctive DNA profiles: A, B, C, D, and E. Profile A was the most frequent DNA pattern and was identified in 55 (75.3%) strains; three closely related and four possibly related profiles were also identified. During period II, 80 (68.8%) of 117 strains showed the same endemic profile A identified during period I, 18 (13.7%) closely related profiles and 18 (13.7%) possibly related profiles and, only one strain presented an unrelated profile. Cluster analysis showed a 96% coefficient of similarity between profile A from period I and profile A from period II, which were considered to be from the same clone. The molecular monitoring of MRSA strains permitted the determination of the clonal dissemination and the maintenance of a dominant endemic strain during a 10-year period and the presence of closely and possibly related patterns for endemic profile A. However, further studies are necessary to improve the understanding of the dissemination of the endemic profile in this hospital.371345-5