Stochastic thermodynamics of Langevin systems under time-delayed feedback control. II. Nonequilibrium steady-state fluctuations.

This paper is the second in a series devoted to the study of Langevin systems subjected to a continuous time-delayed feedback control. The goal of our previous paper [Phys. Rev. E 91, 042114 (2015)PLEEE81539-375510.1103/PhysRevE.91.042114] was to derive second-law-like inequalities that provide bounds to the average extracted work. Here we study stochastic fluctuations of time-integrated observables such as the heat exchanged with the environment, the extracted work, or the (apparent) entropy production. We use a path-integral formalism and focus on the long-time behavior in the stationary cooling regime, stressing the role of rare events. This is illustrated by a detailed analytical and numerical study of a Langevin harmonic oscillator driven by a linear feedback.

Stochastic thermodynamics of Langevin systems under time-delayed feedback control: Second-law-like inequalities.

Response lags are generic to almost any physical system and often play a crucial role in the feedback loops present in artificial nanodevices and biological molecular machines. In this paper, we perform a comprehensive study of small stochastic systems governed by an underdamped Langevin equation and driven out of equilibrium by a time-delayed continuous feedback control. In their normal operating regime, these systems settle in a nonequilibrium steady state in which work is permanently extracted from the surrounding heat bath. By using the Fokker-Planck representation of the dynamics, we derive a set of second-law-like inequalities that provide bounds to the rate of extracted work. These inequalities involve additional contributions characterizing the reduction of entropy production due to the continuous measurement process. We also show that the non-Markovian nature of the dynamics requires a modification of the basic relation linking dissipation to the breaking of time-reversal symmetry at the level of trajectories. The modified relation includes a contribution arising from the acausal character of the reverse process. This, in turn, leads to another second-law-like inequality. We illustrate the general formalism with a detailed analytical and numerical study of a harmonic oscillator driven by a linear feedback, which describes actual experimental setups.

Entropy production and fluctuation theorems for Langevin processes under continuous non-Markovian feedback control.

Continuous feedback control of Langevin processes may be non-Markovian due to a time lag between the measurement and the control action. We show that this requires one to modify the basic relation between dissipation and time reversal and to include a contribution arising from the noncausal character of the reverse process. We then propose a new definition of the quantity measuring the irreversibility of a path in a nonequilibrium stationary state, which can also be regarded as the trajectory-dependent total entropy production. This leads to an extension of the second law, which takes a simple form in the long-time limit. As an illustration, we apply the general approach to linear systems that are both analytically tractable and experimentally relevant.

Stochastic dynamics of N bistable elements with global time-delayed interactions: towards an exact solution of the master equations for finite N.

We consider a network of N noisy bistable elements with global time-delayed couplings. In a two-state description, where elements are represented by Ising spins, the collective dynamics is described by an infinite hierarchy of coupled master equations which was solved at the mean-field level in the thermodynamic limit. When the number of elements is finite, as is the case in actual laser networks, an analytical description was deemed so far intractable and numerical studies seemed to be necessary. In this paper we consider the case of two interacting elements and show that a partial analytical description of the stationary state is possible if the stochastic process is time symmetric. This requires some relationship between the transition rates to be satisfied.

Temperature control for simulated annealing.

The optimal cooling schedule for simulated annealing is formulated to derive a differential equation for the time-dependent temperature T(t). Based on this equation, the long-term behavior of T(t), entropy production, and the Kullback-Leibler entropy are studied. For some simple examples, such as a many-level system and the small scale traveling salesman problem, the explicit time dependence of the temperature is obtained. Some comments are given on simulated annealing based on Tsallis statistics.

Dynamical aspects of an adiabatic piston.

Dynamical aspects of an adiabatic piston are investigated, based on the mass ratio expansion of the master equation for the piston velocity distribution function. Simple theory for piston motion and relaxation of an ideal gas in a cylinder turns out to reproduce our numerical experiments quantitatively.

[Dynamics of interleukin (IL)-18 in serum, synovial fluid and synovial membrane in the patients with rheumatoid arthritis].

OBJECTIVES: IL-18 is a novel cytokine that plays an important role in the Th1 response. The aim of this study is to investigate the dynamics of IL-18 in serum, synovial fluid and synovial membrane in the patients with rheumatoid arthritis. MATERIALS AND METHODS: The serum, synovial fluid and synovial membrane were obtained from RA patients at operation. The levels of IL-18 in the serum and synovial fluid were measured by ELISA. We then examined the expression of IL-18 in synovial tissues using anti-human IL-18 monoclonal antibody in immunohistochemical study. RESULTS: The levels of IL-18 in serum and synovial fluid in RA patients were 193.7 +/- 109.7 pg/ml and 258.8 +/- 238.0 pg/ml, respectively. Compared with OA patients and normal volunteers, the level of IL-18 in RA patients was higher in both serum and synovial fluid. (P < 0.05) In synovial membrane, the cells positive for anti IL-18 antibody were confirmed not only in RA (n = 26) but also in OA (n = 7) patients. The positive cells were the synovial lining cells, macrophages, fibroblasts and endothelial cells. However, a large number of positive cells were demonstrated in synovial tissues in RA compared with OA patients.

[A study of recovery factor about drug addiction recovery center "DARC"].

This study examines the effectiveness of the 'DARC' (Drug Addiction Rehabilitation Center) and its program in treating patients with drug dependence. DARC is the only rehabilitation facility group managed by recovered drug users in Japan. It uses the 'Twelve Step Program' as part of its recovery regime. Through structured questionnaires, the changes of participants' and ex-participants' everyday behavior, their acceptance of spirituality, attitude toward drugs, self-esteem, their coping skills and loneliness were examined. The results revealed: a.. Negative partial correlation between loneliness and everyday behavior. b.. Negative partial correlation between loneliness and positive/effective coping skills. c.. Positive partial correlation between acceptance of 'spirituality' and attitude toward drugs. d.. Positive partial correlation between acceptance of 'spirituality' and positive/effective coping skills. These results suggest that the acceptance of 'spirituality' and decreasing loneliness are important factors in the recovery from drug dependence.

A human homologue of yeast anti-silencing factor has histone chaperone activity.

BACKGROUND: Structural changes in chromatin play essential roles in regulating eukaryotic gene expression. Silencing, potent repression of transcription in Saccharomyces cerevisiae, occurs near telomeres and at the silent mating-type loci, as well as at rDNA loci. This type of repression relates to the condensation of chromatin that occurs in the heterochromatin of multicellular organisms. Anti-silencing is a reaction by which silenced loci are de-repressed. Genetic studies revealed that several factors participate in the anti-silencing reaction. However, actions of factors and molecular mechanisms underlying anti-silencing remain unknown. RESULTS: Here we report the functional activity of a highly evolutionarily conserved human factor termed CIA (CCG1-interacting factor A), whose budding yeast homologue ASF1 has anti-silencing activity. Using yeast two-hybrid screening, we isolated histone H3 as an interacting factor of CIA. We also showed that CIA binds to histones H3/H4 in vitro, and that the interacting region of histone H3 is located in the C-terminal helices. Considering the functional role of CIA as a histone-interacting protein, we found that CIA forms a nucleosome-like structure with DNA and histones. CONCLUSIONS: These results show that human CIA, whose yeast homologue ASF1 is an anti-silencing factor, possesses histone chaperone activity. This leads to a better understanding of the relationship between chromatin structural changes and anti-silencing processes.

Mechanical and Langevin thermostats: Gulton staircase problem.

Dynamics in a Gulton staircase is considered based on a model in which many particles, coupled through an average velocity, are in contact with a Gaussian thermostat. Computer simulation gives information on entropy production, the stationary mass current, and distribution functions of both particle positions and momenta. A Langevin thermostat is also considered for the sake of comparison with a mechanical thermostat.

[A comparison of motivational intervention and knowledge-supplied intervention for weight control in female students living alone: focus on self-efficacy].

The purpose of this study was: 1) to verify if motivational intervention enhances self-efficacy and desire for weight control; and 2) to compare the performance of weight control, desire, and self-efficacy among subjects in the motivational intervention group with those in the knowledge-supplied intervention group. Subjects included twenty-two female students living alone. The participants were divided into two groups of motivational-intervention (experimental group) and knowledge-supplied intervention (control group), consisting of eleven subjects in each group selected at random. A pre-test/post-test control design was used. Intervention in the experimental group consisted of a confirmation of individual reasons for weight control, connecting weight control with a life worth living for, and self-monitoring. Intervention in the control group however, involved instructions, on physiological and biochemical basis of proper weight control. As the result, these are suggested that the motivational intervention associated with enhancement of self-efficacy in weight control and dietary behavior. Compared to knowledge-based intervention, motivational intervention was associated with higher chewing method performance ratios, longer terms of continuing the chewing method, self-efficacy of weight control, self-efficacy of dietary behavior, and desire to weight control.

Evaluation of left ventricular wall motion and function in patients with previous myocardial infarction by three-dimensional 99mTc-HSAD multigated cardiac pool imaging.

To evaluate left ventricular (LV) wall motion stereoscopically from all directions and to calculate the LV volume by three-dimensional (3D) imaging. 99mTc-DTPA human serum albumin-multigated cardiac pool-single photon emission computed tomography (99mTc-MUGA-SPECT) was performed. A new data processing program was developed with the Application Visualization System-Medical Viewer (AVS-MV) based on images obtained from 99mTc-MUGA-SPECT. In patients with previous myocardial infarction, LV function and LV wall motion were evaluated by 3D-99mTc-MUGA imaging. The LV end-diastolic volume (LVEDV) and end-systolic volume (LVESV) were obtained from 3D-99mTc-MUGA images by the surface rendering method, and the left ventricular ejection fraction (LVEF) was calculated at thresholds of 35% (T1), 40% (T2), 45% (T3), and 50% (T4). There was a strong correlation between the LV volume calculated by 3D-99mTc-MUGA imaging at a threshold of 40% and that determined by contrast left ventriculography (LVEDV: 194.7 +/- 36.0 ml vs. 198.7 +/- 39.1 ml, r = 0.791, p < 0.001; LVESV: 91.6 +/- 44.5 ml vs. 93.3 +/- 41.3 ml, r = 0.953, p < 0.001), respectively. When compared with the LVEF data obtained by left ventriculography, significant correlations were found for 3D images reconstructed at each threshold (T1: r = 0.966; T2: r = 0.962; T3: r = 0.958; and T4: r = 0.955). In addition, when LV wall motion obtained by 3D-99mTc-MUGA imaging (LAT and LAO views) was compared with the results obtained by left ventriculography (RAO and LAO views), there was good agreement. 3D-99mTc-MUGA imaging was superior in allowing evaluation of LV wall motion in all directions and in assessment of LV function, since data acquisition and image reconstruction could be done within a short time with the three-detector imaging system and AVS-MV. This method appears to be very useful for the observation of both LV wall motion and LV function in patients with ischemic heart disease, because it is a noninvasive examination.

The beneficial effect of dibutyryl cyclic adenosine monophosphate on warm ischemic injury of the rat liver induced by cardiac arrest.

Dibutyryl cAMP (DBcAMP) has a high membrane permeability, and maintenance of the intracellular cAMP concentration may improve the viability of organs. In this study, the effect of DBcAMP pretreatment on warm ischemic injury of rat livers was evaluated. Warm ischemic liver injury was induced in adult Wistar rats weighing 250-280 g by leaving them at room temperature (22-25 degrees C) after cardiac arrest. The hepatic cAMP concentration, %ATP, and trypan blue-positive nuclear ratio were determined after different durations of warm ischemia. In addition, transaminase and endothelin-1 (ET-1) release into the perfusate were examined during 60 min of isolated liver perfusion with Krebs-Henseleit solution. The optimal dose and time of DBcAMP pretreatment were determined to be 15 mg/kg and 60 min prior to warm ischemia, respectively. Data on the trypan blue-positive nuclear ratio and the release of transaminases and ET-1 revealed that warm ischemia first damaged the endothelial cells and then the hepatocytes. DBcAMP pretreatment appeared to protect the liver from warm ischemic injury by increasing the intracellular cAMP concentration and stabilizing the cell membranes of endothelial cells and hepatocytes.

Japanese risk behaviors and their HIV/AIDS-preventive behaviors.

This study is to identify the risk behaviors of the Japanese that may lead to HIV infection and the behaviors that prevent such infection, as well as their background factors. Two behavioral surveys were conducted for the present study. (1) For international comparison on knowledge, attitudes, beliefs, and practices (KABP) related to HIV/AIDS, we conducted a survey on a sample of 10,000 adults, randomly selected from a nationwide population in Japan; and (2) for sexual partner relation, we conducted a survey on a sample of 10,000 adults randomly selected from a population in five major cities of Japan. Our main findings include: (1) Most of the Japanese adult did not regard AIDS as a major threat in the area where they lived; (2) People in their twenties are too casual about "having sex without using a condom with someone they've met for the first time and know little about"; (3) Thirteen percent (19% male, 8% female) of those with a steady sex partner including a spouse, on average, had sex with 2.4 non-steady partners in the previous year; and (4) Only 25 percent used condoms always when they engaged in casual sex during the previous four weeks. These risk behaviors of the Japanese adults might lead to an explosive rise in the number of HIV-infected in the near future unless steps are taken immediately to prevent it.

Evaluation of functional recovery of regenerating rat liver after partial hepatectomy using 31P-NMR spectroscopy.

Using 31P-NMR spectroscopy, we studied the process of the functional recovery of the regenerating rat liver at 1-5 weeks after a 65% partial hepatectomy from the viewpoint of phosphate metabolism. Portal vein clamping (20 min) or fructose administration (250 mg/kg body weight) was performed to temporarily reduce adenosine triphosphate (ATP) content in the remnant liver. Changes in ATP level were observed for 60 min after declamping the portal vein or after fructose administration. Significant differences in the increased ATP levels after declamping the portal vein or after fructose administration were observed in each hepatectomized group. Until 3 weeks after hepatectomy, ATP levels during 60 min after declamping the portal vein or after fructose administration were significantly lower than those in the nonresected control rats. However, the increase in ATP in the 4-week group was almost identical to the increase in the control group throughout the 60 min. Remnant liver weight already returned to the nonresected control level 1 week after hepatectomy, and remained constant thereafter. On the other hand, the final ATP levels 60 min after declamping the portal vein or after fructose administration returned to the nonresected control level only after 4 weeks following hepatectomy. These results demonstrate that from the viewpoint of ATP synthesis, functional recovery of the regenerating liver to normal can be observed within 4 weeks after partial hepatectomy.

[Clinicopathological study of interstitial foam cells in idiopathic membranous nephropathy. Consideration of the appearance of interstitial foam cells in renal tissue].

We conducted an immunohistological investigation on the pathogenesis of interstitial foam cell formation in patients with idiopathic membranous nephropathy (MN). The patients were divided into two groups: Group I consisted of 23 MN patients with interstitial foam cells; Group II consisted of the other 159 patients without foam cells. Age at renal biopsy, duration of proteinuria, blood pressure and other clinical parameters were not significantly different between the two groups. The proportion of nephrotic patients in Group I was 52.2% (12/23), and was not significantly different from that in Group II (48.4%, 77/159). Renal biopsy specimens were examined by immunoperoxidase studies using monoclonal antibodies. The interstitial foam cells were positive for EBM11 (CD68) and 25F9, which are markers of macrophage (M phi) and mature M phi, respectively, but did not express markers of T cells. In interstitial infiltrating cells, both M phi and T cells were observed, but mature M phi were seldom seen. Furthermore, LFA-1 and ICAM-1, but not ICAM-3 (the third ligand for LFA-1) were observed in the interstitial foam cells. LFA-1 and ICAM-3 were observed mainly in interstitial infiltrating cells, but ICAM-1 was observed to a much lesser extent in these cells. These results suggest that interstitial foam cells in MN may be independent of severe hyperlipidemia and proteinuria, and that there may be different mechanisms underlying the accumulation of interstitial foam cells and infiltrating m phi s. Further investigations are required to clarify the pathogenesis of interstitial foam cells in renal tissue.