96 research outputs found

    Thermodynamic Variables In The Context Of A Nonequilibrium Statistical Ensemble Approach

    Get PDF
    We consider the question of the definition of thermodynamic-like variables in the context of a statistical thermodynamics, which is a large generalization of Gibbs statistical thermostatics and linear and local-equilibrium classical irreversible thermodynamics. It is based on a nonequilibrium ensemble approach known as the nonequilibrium statistical operator method. Some of these quasithermodynamic variables are characteristic of the nonequilibrium state and go to zero in the limit of local or global equilibrium, but others go over the thermodynamic variables that are present in such a limit. We consider in particular temperature-like variables for the different subsystems of the sample. For illustration we apply the theory to the study of optical properties of highly photoexcited plasma in semiconductors, following a good agreement between theory and experimental data. It is shown that high-resolution spectroscopy provides an excellent experimental testing ground for corroboration of the theoretical concepts, and a quite appropriate way for characterizing and measuring nonequilibrium thermodynamic-like variables. © 1997 American Institute of Physics.1071873837396Tisza, L., (1991) Thermodynamics: History and Philosophy, pp. 515-522. , edited by K. Martinas, L. Ropolyi, and P. Szegedi World Scientific, SingaporeGarcia-Colin, L.S., Vasconcellos, A.R., Luzzi, R., (1994) J. Non-Equilib. Thermodyn., 19, p. 24Luzzi, R., Vasconcellos, A.R., (1997) Physica A, 241, p. 677Nettleton, R.E., Sobolev, S.L., (1995) J. Non-Equilib. Thermodyn., 20, p. 205Sieniutycz, S., Solomon, P., (1990) Nonequilibrium Theory and Extremum Principles, , Taylor and Francis, New YorkVansconcellos, A.R., Luzzi, R., Garcia-Colin, L.S., (1991) Phys. Rev. A, 43, p. 6622(1991) Phys. Rev. A, 43, p. 6633(1995) J. Non-Equilib. Thermodyn., 20, p. 103(1995) J. Non-Equilib. Thermodyn., 20, p. 119(1995) Int. J. Mod. Phys. B, 9, p. 1933(1995) Int. J. Mod. Phys. B, 9, p. 1945(1995) Physica A, 221, p. 478(1995) Physica A, 221, p. 495Vasconcellos, A.R., Luzzi, R., Esperidião, A.S., (1995) Phys. Rev. B, 52, p. 5021Vasconcellos, A.R., Luzzi, R., Jou, D., Casas-Vázquez, J., (1995) Phys. Rev. B, 52, p. 5030Luzzi, R., Vasconcellos, A.R., Casas-Vázquez, J., Jou, D., (1997) Physica A, 234, p. 699Hobson, A., (1966) J. Chem. Phys., 45, p. 1352(1966) Am. J. Phys., 34, p. 411Jaynes, E.T., (1957) Phys. Rev., 106, p. 620(1957) Phys. Rev., 108, p. 171Zubarev, D.N., (1971) Neravnovesnaia Statisticheskaia Termodinamika, , Izd. Nauka, Moscow(1974) Nonequilibrium Statistical Thermodynamics, , English transi.: Consultants Bureau, New YorkZubarev, D.N., Morozov, V., Röpke, G., (1996) Statistical Mechanics of Nonequilibrium Processes, , Akademie Verlag, BerlinZubarev, D.N., Kalashnikov, V.P., (1970) Math. Theor. Phys., 1, p. 108. , USSRLuzzi, R., Vasconcellos, A.R., (1990) Fortschr. Phys. Prog. Phys., 38, p. 887Ramos, J.G., Vasconcellos, A.R., Luzzi, R., (1995) Fortsch. Phys. Prog. Phys., 43, p. 265Casimir, H.B.G., Du Pre, F.K., (1938) Physica, 5, p. 507Abragam, A., (1961) The Principles of Nuclear Magnetism, , Oxford, University Press, OxfordWang Chang, C.S., Uhlenbeck, G.E., De Boer, J., (1964) Studies of Statistical Mechanics, 2. , edited by J. de Boer and G. E. Uhlenbeck North Holland. AmsterdamLandau, L.D., (1937) Zh. Eksp. Teor. Fiz., 7, p. 203Dougal, A.A., Goldstein, L., (1958) Phys. Rev., 109, p. 615Fröhlich, H., (1947) Proc. R. Soc. London, 188 A, p. 521Shklovskii, V.A., (1976) Fiz. Tverd. Tela, 17, p. 3076(1975) Sov. Phys. Solid State, 17, p. 2040Shah, J., Leite, R.C.C., (1969) Phys. Rev. Lett., 22, p. 1304Shah, J., Leite, R.C.C., Scott, J.F., (1970) Solid State Commun., 8, p. 1089Feshbach, H., (1987) Phys. Today, 11, p. 9Garcia-Colin, L.S., Green, M.S., (1966) Phys. Rev., 150, p. 153Casas-Vázquez, J., Jou, D., (1981) J. Phys. A, 14, p. 1225Jou, D., Casas-Vázquez, J., (1988) J. Phys. A, 20, p. 5371(1990) Physica A, 163, p. 47(1992) Phys. Rev. A, 45, p. 8371(1993) Phys. Rev. F, 48, p. 3201Casas-Vázquez, J., Jou, D., (1994) Phys. Rev. F, 49, p. 1040Kirkwood, S.G., (1946) J. Chem. Phys., 14, p. 180Green, M.S., (1952) J. Chem. Phys., 20, p. 1281(1954) J. Chem. Phys., 22, p. 398Zwanzig, R.W., (1961) Phys. Rev., 124, p. 983Brittin, W.E., Downs, B.W., Downs, J., (1961) Lecture Notes in Theoretical Physics, 3. , Wiley-Interscience, New YorkMori, H., (1965) Prog. Theor. Phys. Jpn., 33, p. 423(1965) Prog. Theor. Phys. Jpn., 34, p. 399Salam, A., Vladimirov, V.S., Logunov, A.A., (1992) Teor. Mat. Fiz., 92, p. 179(1993) Theor. Math. Phys., 92, p. 817Logunov, A.A., Vladimirov, V.S., (1979) Teor. Mat. Fiz., 40, p. 147(1980) Theor. Math. Phys., 40, p. 655Bogoliubov, N.N., (1967) Lectures in Quantum Statistics Vols. I and II, 1-2. , Gordon and Breach, New York, respectivelyBogoliubov, N.N., (1962) Studies in Statistical Mechanics I, , edited by . de Boer and G. E. Uhleenbeck North Holland, AmsterdamUhlenbeck, G.E., (1963) Lectures in Statistical Mechanics, , edited by M. Kac Am. Math. Soc., Providence, RIBuishvili, L.L., Sviadadze, M.D., (1972) Physica, 59, p. 697Vasconcellos, A.R., Algarte, A.C., Luzzi, R., (1990) Physica A, 166, p. 517Prigogine, I., (1975) J. Quantum Chem., 9, p. 443(1973) Nature (London), 246, p. 67Gell-Mann, M., Goldberger, M.L., (1953) Phys. Rev., 91, p. 398Lauck, L., Vasconcellos, A.R., Luzzi, R., (1990) Physica A, 168, p. 789Madureira, A.J., Vasconcellos, A.R., Luzzi, R., Lauck, L., (1997) A Nonlinear Kinetic Theory Based on a Nonequilibrium Statistical Ensemble Formalism, , IFGW-Unicamp Internal Report and future publicationAkhiezer, A.I., Peletminskii, S.V., (1981) Methods of Statistical Physics, , Pergamon, OxfordTenan, M.A., Vasconcellos, A.R., Luzzi, R., (1996) Fortschr. Phys. Prog. Phys., 45, p. 1Del Rio, J.L., Garcia-Colin, L.S., (1991) Phys. Rev. A, 43, p. 6657(1993) Phys. Rev. E, 48, p. 819Peletminskii, S.V., Sokolovskii, A.I., (1974) Teor. Mat. Fiz., 18, p. 121(1974) Theor. Math. Phys., 18, p. 85Madureira, A.J., Vasconcellos, A.R., Luzzi, R., Flux operators of dynamical quantities in a statistical ensemble approach (1997) J. Stat. Phys. First and First Revised Versions, , IFGW-Unicamp Internal Report (submitted)Courant, R., Hilbert, D., (1953) Methods of Mathematical Physics, 1, pp. 184-186. , Wiley-Interscience, New YorkLuzzi, R., Miranda, L.C., (1978) Phys. Rep., 43, p. 423Algarte, A.C., Vasconcellos, A.R., Luzzi, R., (1992) Phys. Status Solidi B, 173, p. 487Pines, D., Nozières, Ph., (1966) The Theory of Quantum Liquids I, , Benjamin, Reading, MAAschroft, N.W., Mermin, N.D., (1976) Solid State Physics, , Holt, Reinhart, and Winston. New YorkElci, A., Scully, M.O., Smirl, A.L., Matter, J.C., (1977) Phys. Rev. B, 16, p. 191Collet, J., Amand, T., Pugnet, M., (1983) Phys. Lett. A, 96, p. 368Kim, D., Yu, P., (1990) Phys. Rev. Lett., 64, p. 946Martin, P.C., (1968) Many-body Physics, , edited by C. de Witt and R. Balian Gordon and Breach, New YorkZubarev, D.N., (1980) Usp. Fiziol. Nauk, 71, p. 71(1960) Usp., 23, p. 320Kalashnikov, V.P., (1971) Teor. Mat. Fiz., 9, p. 94(1971) Theor. Math. Phys., 9, p. 1003Luzzi, R., Vasconcellos, A.R., (1980) J. Stat. Phys., 23, p. 539See, for example. Sec. 3.1 in Ref. 39Vasconcellos, A.R., Luzzi, R., (1975) Solid State Commun., 17, p. 501Turtelli, R.S., Castro, A.R.B., Leite, R.C.C., (1975) Solid State Commun., 16, p. 969See. for example, Sec. 3.2 in Ref. 39Daly, T., Mahr, H., (1977) LASSP-Report 2828, , Cornell University, IthacaAlgarte, A.C., Vasconcellos, A.R., Luzzi, R., (1996) Braz. J. Phys., 26, p. 543Seymour, R.J., Junnarkar, M.R., Alfano, R.R., (1982) Solid State Commun., 41, p. 657See, for example, Sec. 3.3 in Ref. 39Motisuke, P., (1977), Ph.D. thesis UNICAMP. Campinas, São Paulo, BrazilMotisuke, P., Argüello, C.A., Luzzi, R., (1977) Solid State Commun., 23, p. 617Cerdeira, F., (1993) Braz. J. Phys., 23, p. 3Mendez, E.E., Agulló-Rueda, F., Hong, J.M., (1988) Phys. Rev. Lett., 60, p. 2426Freire, V.N., (1988), Ph.D. thesis UNICAMP, Campinas. São Paulo, BrazilFreire, V.N., Vasconcellos, A.R., Luzzi, R., (1989) Phys. Rev. B, 39, p. 13264Loudon, R., (1964) Adv. Phys., 13, p. 423Von Der Linde, D., Kuhl, J., Klingerberg, H., (1980) Phys. Rev. Lett., 44, p. 1505Algarte, A.C., Vasconcellos, A.R., Luzzi, R., (1997) Phys. Rev. B, 54, p. 11311Algarte, A.C., Vasconcellos, A.R., Luzzi, R., (1896) Proceedings of the 18th International Conference on the Physics of Semiconductors, , edited by O. Engström, World Scientific, SingaporePhys. Rev. B, , in pressDe Groot, S.R., Mazur, P., (1962) Nonequilibrium Thermodynamics, , North Holland, AmsterdamGlansdorff, P., Prigogine, I., (1971) Thermodynamics of Structure, Stability and Fluctuations, , Wiley-Interscience, New YorkMeixner, J., (1974) Foundations of Continuum Thermodynamics, , edited by J. J. Domingos, M. N. Nina, and J. H. Whitelaw MacMillan, LondonMüller, I., (1971) Arch. Ration. Mech. Anal., 40, p. 1Muschik, W., (1977) Arch. Ration. Mech. Anal., 66, p. 379(1979) J. Non-Equilib. Thermodyn., 4, p. 277Keizer, J., (1976) J. Chem. Phys., 65, p. 4431(1978) J. Chem. Phys., 69, p. 2609(1985) J. Chem. Phys., 82, p. 2751(1987) Statistical Thermodynamics of Nonequilibrium Processes, , Springer, New YorkNettleton, R.E., (1994) Can. J. Phys., 72, p. 106Luzzi, R., Ramos, J.G., Vasconcellos, A.R., (1997) On the Question of Entropy and Temperature in Irreversible Thermodynamics, , IFGW-Unicamp Internal Report Philos. Trans. R. Soc. London (submitted)Alfano, R.R., (1986) New Techniques and Ideas in Quantum Measurement Theory, , edited by D. M. Greenberg New York Academy of Science, New YorkRamos, J.G., Vasconcellos, A.R., Luzzi, R., (1997) On the Truncation Procedure in Informational Statistical Thermodynamics, , IFGW-Unicamp Internal Report and future publicationMeixner, J., (1973) Rheol. Acta, 12, p. 46

    Status of QCD

    Full text link
    I have been asked to discuss the status of QCD. It seems to me that there are three main points to be made about the present status of QCD: \bullet QCD is right, and we can do many beautiful things with it. \bullet There are several important concrete problems that lie just beyond the edge of our current understanding. \bullet There are some foundational issues in QCD, and some recent developments, that may point toward entirely new directions. These points will, I believe, emerge quite clearly from the following more detailed discussion. The discussion will be in three parts. I'll first discuss elementary processes, then more complicated processes, and then finally foundational issues.Comment: 28 pages, use Phyzzx, figures available by FAX or mail on request, IASSNS-HEP-93/6

    Higher-order hydrodynamics: Extended Fick's Law, evolution equation, and Bobylev's instability

    Get PDF
    A higher-order hydrodynamics for material motion in fluids, under arbitrary nonequilibrium conditions, is constructed. We obtain what is a generalized-to that conditions-Fick-type Law. It includes a representation of Burnett-type contributions of all order, in the form of a continuous-fraction expansion. Also, the equation includes generalized thermodynamic forces. which are characterized and discussed. All kinetic coefficients are given as correlations of microscopic mechanical quantities averaged over the nonequilibrium ensemble, and then are time- and space-dependent as a consequence of accounting for the dissipative processes that are unfolding in the medium. An extended evolution equation for the density of particles is derived, and the conditions when it goes over restricted forms of the type of the telegraphist equation and Fick's diffusion equation are presented. (C) 2002 American Institute of Physics.11641571158

    Evolution of dissipative processes via a statistical thermodynamic approach. II. Thermodynamic properties of a fluid of bosons

    Get PDF
    On the basis of the generalized Mori-Heisenberg-Langevin equations presented in the preceding paper, we derive and analyze the informational-statistical thermodynamic properties of a fluid of bosons away from equilibrium. We derive the informational entropy and its production, proceeding to an analysis of the several contributions to these state functions arising out of the evolution of dissipative processes in the system. (C) 1998 American Institute of Physics.108187580758

    Work and heat fluctuations in two-state systems: a trajectory thermodynamics formalism

    Full text link
    Two-state models provide phenomenological descriptions of many different systems, ranging from physics to chemistry and biology. We investigate work fluctuations in an ensemble of two-state systems driven out of equilibrium under the action of an external perturbation. We calculate the probability density P(W) that a work equal to W is exerted upon the system along a given non-equilibrium trajectory and introduce a trajectory thermodynamics formalism to quantify work fluctuations in the large-size limit. We then define a trajectory entropy S(W) that counts the number of non-equilibrium trajectories P(W)=exp(S(W)/kT) with work equal to W. A trajectory free-energy F(W) can also be defined, which has a minimum at a value of the work that has to be efficiently sampled to quantitatively test the Jarzynski equality. Within this formalism a Lagrange multiplier is also introduced, the inverse of which plays the role of a trajectory temperature. Our solution for P(W) exactly satisfies the fluctuation theorem by Crooks and allows us to investigate heat-fluctuations for a protocol that is invariant under time reversal. The heat distribution is then characterized by a Gaussian component (describing small and frequent heat exchange events) and exponential tails (describing the statistics of large deviations and rare events). For the latter, the width of the exponential tails is related to the aforementioned trajectory temperature. Finite-size effects to the large-N theory and the recovery of work distributions for finite N are also discussed. Finally, we pay particular attention to the case of magnetic nanoparticle systems under the action of a magnetic field H where work and heat fluctuations are predicted to be observable in ramping experiments in micro-SQUIDs.Comment: 28 pages, 14 figures (Latex

    Spin-transfer in an open ferromagnetic layer: from negative damping to effective temperature

    Full text link
    Spin-transfer is a typical spintronics effect that allows a ferromagnetic layer to be switched by spin-injection. Most of the experimental results about spin transfer are described on the basis of the Landau-Lifshitz-Gilbert equation of the magnetization, in which additional current-dependent damping factors are added, and can be positive or negative. The origin of the damping can be investigated further by performing stochastic experiments, like one shot relaxation experiments under spin-injection in the activation regime of the magnetization. In this regime, the N\'eel-Brown activation law is observed which leads to the introduction of a current-dependent effective temperature. In order to justify the introduction of these counterintuitive parameters (effective temperature and negative damping), a detailed thermokinetic analysis of the different sub-systems involved is performed. We propose a thermokinetic description of the different forms of energy exchanged between the electric and the ferromagnetic sub-systems at a Normal/Ferromagnetic junction. The corresponding Fokker Planck equations, including relaxations, are derived. The damping coefficients are studied in terms of Onsager-Casimir transport coefficients, with the help of the reciprocity relations. The effective temperature is deduced in the activation regime.Comment: 65 pages, 10 figure

    Lifestyle factors and visceral adipose tissue: Results from the PREDIMED-PLUS study

    Get PDF
    Background: Visceral adipose tissue (VAT) is a strong predictor of cardiometabolic health, and lifestyle factors may have a positive influence on VAT depot. This study aimed to assess the cross-sectional associations between baseline levels of physical activity (PA), sedentary behaviours (SB) and adherence to the Mediterranean diet (MedDiet) with VAT depot in older individuals with overweight/obesity and metabolic syndrome. Methods: Baseline data of the PREDIMED-Plus study including a sample of 1,231 Caucasian men and women aged 55-75 years were used. Levels of leisure-time PA (total, light, and moderate-to-vigorous, in METs·min/day) and SB (total and TV-viewing, in h/day) were evaluated using validated questionnaires. Adherence to the MedDiet was evaluated using a 17-item energy-restricted MedDiet (erMedDiet) screener. The chair-stand test was used to estimate the muscle strength. VAT depot was assessed with DXA-CoreScan. Multivariable adjusted linear regression models were used to evaluate the association between lifestyle factors and VAT. For the statistics we had used multiadjusted linear regression models. Results: Total leisure-time PA (100 METs·min/day: β -24.3g, -36.7;-11.9g), moderate-to-vigorous PA (β -27.8g, 95% CI -40.8;-14.8g), chair-stand test (repeat: β -11.5g, 95% CI -20.1;-2.93g) were inversely associated, and total SB (h/day: β 38.2g, 95% CI 14.7;61.7) positively associated with VAT. Light PA, TV-viewing time and adherence to an erMedDiet were not significantly associated with VAT. Conclusions: In older adults with overweigh/obesity and metabolic syndrome, greater PA, muscle strength, and lower total SB were associated with less VAT depot. In this study, adherence to an erMedDiet was not associated with lower VAT

    Nuclear translocation of haeme oxygenase-1 is associated to prostate cancer

    Get PDF
    The role of oxidative stress in prostate cancer has been increasingly recognised. Acute and chronic inflammations generate reactive oxygen species that result in damage to cellular structures. Haeme oxygenase-1 (HO-1) has cytoprotective effects against oxidative damage. We hypothesise that modulation of HO-1 expression may be involved in the process of prostate carcinogenesis and prostate cancer progression. We thus studied HO-1 expression and localisation in 85 samples of organ-confined primary prostate cancer obtained via radical prostatectomy (Gleason grades 4–9) and in 39 specimens of benign prostatic hyperplasia (BPH). We assessed HO-1 expression by immunohistochemical staining. No significant difference was observed in the cytoplasmic positive reactivity among tumours (84%), non-neoplastic surrounding parenchyma (89%), or BPH samples (87%) (P=0.53). Haeme oxygenase-1 immunostaining was detected in the nuclei of prostate cancer cells in 55 of 85 (65%) patients but less often in non-neoplastic surrounding parenchyma (30 of 85, 35%) or in BPH (9 of 39, 23%) (P<0.0001). Immunocytochemical and western blot analysis showed HO-1 only in the cytoplasmic compartment of PC3 and LNCaP prostate cancer cell lines. Treatment with hemin, a well-known specific inducer of HO-1, led to clear nuclear localisation of HO-1 in both cell lines and highly induced HO-1 expression in both cellular compartments. These findings have demonstrated, for the first time, that HO-1 expression and nuclear localisation can define a new subgroup of prostate cancer primary tumours and that the modulation of HO-1 expression and its nuclear translocation could represent new avenues for therapy

    Ribonucleotide reductases of Salmonella Typhimurium : transcriptional regulation and differential role in pathogenesis

    Get PDF
    Ribonucleotide reductases (RNRs) are essential enzymes that carry out the de novo synthesis of deoxyribonucleotides by reducing ribonucleotides. There are three different classes of RNRs (I, II and III), all having different oxygen dependency and biochemical characteristics. Salmonella enterica serovar Typhimurium (S. Typhimurium) harbors class Ia, class Ib and class III RNRs in its genome. We have studied the transcriptional regulation of these three RNR classes in S. Typhimurium as well as their differential function during infection of macrophage and epithelial cells. Deletion of both NrdR and Fur, two main transcriptional regulators, indicates that Fur specifically represses the class Ib enzyme and that NrdR acts as a global repressor of all three classes. A Fur recognition sequence within the nrdHIEF promoter has also been described and confirmed by electrophoretic mobility shift assays (EMSA). In order to elucidate the role of each RNR class during infection, S. Typhimurium single and double RNR mutants (as well as Fur and NrdR mutants) were used in infection assays with macrophage and epithelial cell lines. Our results indicate class Ia to be mainly responsible for deoxyribonucleotide production during invasion and proliferation inside macrophages and epithelial cells. Neither class Ib nor class III seem to be essential for growth under these conditions. However, class Ib is able to maintain certain growth in an nrdAB mutant during the first hours of macrophage infection. Our results suggest that, during the early stages of macrophage infection, class Ib may contribute to deoxyribonucleotide synthesis by means of both an NrdR and a Fur-dependent derepression of nrdHIEF due to hydrogen peroxide production and DNA damage associated with the oxidative burst, thus helping to overcome the host defenses
    corecore