Entropy production and time-asymmetry in the presence of strong interactions

It is known that the equilibrium properties of open classical systems that are strongly coupled to a heat bath are described by a set of thermodynamic potentials related to the system's Hamiltonian of mean force. By adapting this framework to a more general class of non-equilibrium states, we show that the equilibrium properties of the bath can be well-defined, even when the system is arbitrarily far from equilibrium and correlated with the bath. These states, which retain a notion of temperature, take the form of conditional equilibrium distributions. For out-of-equilibrium processes we show that the average entropy production quantifies the extent to which the system-bath state is driven away from the conditional equilibrium distribution. In addition, we show that the stochastic entropy production satisfies a generalised Crooks relation and can be used to quantify time-asymmetry of correlated non-equilibrium processes. These results naturally extend the familiar properties of entropy production in weakly-coupled systems to the strong coupling regime. Experimental measurements of the entropy production at strong coupling could be pursued using optomechanics or trapped ion systems, which allow strong coupling to be engineered.Comment: 8 pages, 1 figure, comments welcom

Leggett-Garg inequalities for quantum fluctuating work

The Leggett-Garg inequalities serve to test whether or not quantum correlations in time can be explained within a classical macrorealistic framework. We apply this test to thermodynamics and derive a set of Leggett- Garg inequalities for the statistics of fluctuating work done on a quantum system unitarily driven in time. It is shown that these inequalities can be violated in a driven two-level system, thereby demonstrating that there exists no general macrorealistic description of quantum work. These violations are shown to emerge within the standard Two-Projective-Measurement scheme as well as for alternative definitions of fluctuating work that are based on weak measurement. Our results elucidate the influences of temporal correlations on work extraction in the quantum regime and highlight a key difference between quantum and classical thermodynamics.Comment: v2, 1 figure, accepted version to appear in Entropy (Special Issue on "Quantum Thermodynamics II"

Time-reversal symmetric work distributions for closed quantum dynamics in the histories framework

A central topic in the emerging field of quantum thermodynamics is the definition of thermodynamic work in the quantum regime. One widely used solution is to define work for a closed system undergoing non-equilibrium dynamics according to the two-point energy measurement scheme. However, due to the invasive nature of measurement the two-point quantum work probability distribution leads to inconsistencies with two pillars of thermodynamics: it breaks the first law and the time-reversal symmetry expected for closed dynamics. We here introduce the quantum histories framework as a method to characterise the thermodynamic properties of the unmeasured, closed dynamics. Extending the classical phase space trajectories to continuous power operator trajectories allows us to derive an alternative quantum work distribution for closed quantum dynamics that fulfils the first law and is time-reversal symmetric. We find that the work distribution of the unmeasured dynamics leads to deviations from the classical Jarzynski equality and can have negative values highlighting distinctly non-classical features of quantum work.Comment: 18 pages, 2 figures, comments welcom

Oil prices: backward to the future?

A useful first guess about the future spot price of a commodity is usually found in its current futures price. But it doesn’t work that way when the commodity in question is oil. This Commentary explains why the characteristics of oil, particularly the value it can offer its owner by remaining in the ground, cloud the information that oil futures prices give about future oil prices.Petroleum industry and trade ; Futures

Attitude accessibility and education: Students\u27 reported attitudes toward peers with disabilities in parochial and public schools.

Students\u27 attitudes toward peers with disabilities may be influenced by a variety of factors. Two potential factors are curriculum of the school and integration of students with disabilities with nondisabled peers. Inclusion of students with disabilities in the regular classroom will increase experience and exposure. Further, a religious aspect of a curriculum may positively or negatively affect the reported attitudes of students in parochial schools. The purpose of the present study was to describe possible differences in curriculum and students\u27 attitudes toward peers with disabilities in parochial and public schools. Elementary school children from parochial and public schools were interviewed to determine attitudes toward peers with disabilities. Students from the schools did not differ in their attitude accessibility, suggesting that parochial and public school students have similar attitude strength toward peers with disabilities. Differences in how the schools approached the topic of disabilities emerged, with public schools emphasizing equality and parochial schools stressing empathy. Further, the students expressed these differences in values through their responses. Overall, the students did not have a firm understanding of the definition of a disability, and neglected to consider non-visible differences such as learning disabilities. Obtained responses suggest that students need more education and knowledge on individuals with disabilities

Characterization of COPD with biomarkers of inflammation and quantitative CT

BACKGROUND The aim of this thesis was to investigate the role of inflammation in the airways and in the systemic compartment in COPD compared to healthy subjects, and to investigate the relationship between inflammation and the clinical and radiological features of COPD.METHODS 182 COPD patients and 96 healthy control subjects were recruited. Post-bronchodilator spirometry, smoking history, body mass index (BMI), exacerbation frequency, St George's Respiratory Questionnaire (SGRQ) scores, MRC dyspnoea and chronic bronchitis scores, oxygen saturations, 6 minute walking distance and BODE index scores were recorded. Highly sensitive C-reactive protein (CRP), total white cell count and neutrophils were measured in blood. Percentage (%) neutrophils, IL-lp, IL-6 and IL-8 were measured in induced sputum. COPD patients had a quantitative CT scan on inspiration and expiration. Lung volume and density (pixel index -910 HU, pixel index -950 HU, and 15th percentile) were determined using in-house software.RESULTS Systemic inflammation was increased in COPD subjects compared to healthy controls: CRP (p<0.001), blood neutrophils (p<0.001). Pulmonary inflammation was also increased in COPD subjects compared to healthy controls: induced sputum % neutrophils (p=0.001), IL-6 (p=0.02) and IL-8 (p=0.01). Induced sputum IL-1J3 was not increased in COPD compared to controls. Blood neutrophils, CRP, sputum IL-6 and IL-8 were higher in COPD patients compared to healthy controls after adjusting for age, gender and smoking status. Induced sputum was not reliably attainable particularly in healthy control subjects (sample available for 65% of COPD subjects and 26% of healthy controls). In COPD subjects, blood neutrophils (p=0.03) and sputum % neutrophils (p=0.004) were independently related to FEVi after adjusting for age, gender, smoking status and inhaled corticosteroid use. Blood neutrophils and CRP correlated significantly with each other (r=0.408, p<0.001), but were not associated with any of the sputum markers of inflammation. Systemic inflammation was associated with SGRQ total score (neutrophils p=0.02, CRP p<0.001) and MRC dyspnoea score (neutrophils p=0.005, CRP p=0.003) after adjusting for FEVi and smoking status. Blood neutrophils (p=0.02) were associated with oxygen saturations < 93%. BODE index scores correlated with blood neutrophils, (p=0.005), CRP (p=0.03) and sputum IL-8 (p=0.02). After adjusting for potential confounding factors; exacerbation frequency and BMI were not associated with markers of blood or sputum inflammation. Quantitative CT lung volume and density (pixel index -910, pixel index -950 and 15th percentile) on inspiration and expiration were associated with postbronchodilator FEVi % predicted and FEVi/FVC ratio (p<0.001) but not with any of the markers of pulmonary or systemic inflammation. Expiratory CT parameters correlated better with lung function than inspiratory parameters. Lung volumes were inversely associated with BMI on inspiration (r=-0.225, p=0.015) and expiration (r=-0.296, p=0.001). BMI was associated with 15th percentile on inspiration (r=0.518, p<0.001) and expiration (r=0.534, p<0.001) and inversely with pixel index -910 and -950 (p<0.001). BMI was associated with lung density independent of airflow limitation (p=0.03). Lung volume and density were not associated with age, gender, current smoking status, smoking pack years, SGRQ scores, MRC dyspnoea or chronic bronchitis score, exacerbation frequency, oxygen saturations or BODE index.CONCLUSION Markers of inflammation in blood and sputum were increased in COPD compared to healthy controls. Blood and sputum % neutrophils were associated with airflow limitation, but not with lung density. Pulmonary and systemic inflammatory markers had different profiles according to different clinical features of COPD. Inflammatory markers and lung density may be useful in characterizing COPD patients in addition to airflow limitation alone