State Entropy Research Articles

From the Viewpoint of Water-Sediment Characters to Approach the General Criteria for Waterway Regulating with Complex Shoals

Compared with each other of existed schemes and effects of the waterway regulating with complex shoals, from the viewpoint of water-sediment interacting evolutional properties and their effects on complex shoals of waterway, the results show that, the evolutional processes of channel morphology observe the principles of maximum entropy in equilibrium state and minimum entropy production rate in non-equilibrium state, in energy words, it is the minimum energy dissipation rate. The vortex moving dominates the sediment transport. From the practical engineering viewpoint, the general criteria for waterway regulating with complex shoals were investigated, the results may be valuable to regulating study of the mountain rivers.

Stabilization of a protein conferred by an increase in folded state entropy

Entropic stabilization of native protein structures typically relies on strategies that serve to decrease the entropy of the unfolded state. Here we report, using a combination of experimental and computational approaches, on enhanced thermodynamic stability conferred by an increase in the configurational entropy of the folded state. The enhanced stability is observed upon modifications of a loop region in the enzyme acylphosphatase and is achieved despite significant enthalpy losses. The modifications that lead to increased stability, as well as those that result in destabilization, however, strongly compromise enzymatic activity, rationalizing the preservation of the native loop structure even though it does not provide the protein with maximal stability or kinetic foldability.

Drug interaction models are better predictors of tolerance/ response to noxious stimuli compared to individual measured parameters

Background and Goal of Study: This study continues the pursuit of the parameter with the best correlation to the probability of response to noxious stimuli of different intensity. We used data from a previous study by Heyse et al.1 on the interaction of sevoflurane and remifentanil to compare several parameters. Materials and Methods: After institutional review board approval, 40 adult patients were randomised to receive different combinations of sevoflurane (Sevo) and remifentanil (Remi) according to a criss-cross design. After reaching pseudo-steady state, the patients were assessed for tolerance of 'shake and shout' (SAS), tetanic stimulation (TET), insertion of laryngeal mask airway (LMA) and laryngoscopy (LAR). Bispectral index (BIS), state and response entropy (SE, RE), composite variability index (CVI) and surgical pleth index (SPI) were either recorded or computed from raw electroencephalographic and plethysmographic data retrospectively. Sevo and Remi concentrations were recorded. The combined potency of Sevo and Remi according to the fixed C50O hierarchical interaction model (U) and the noxious stimulation response index (NSRI) were the population-based predictors. We used the prediction probability (PK) to assess the performance of these parameters on the probability of response. Bootstrapping (n=1000) was used to produce 84%-confidence intervals of the PKs, with significance being achieved if the confidence intervals did not overlap (p <0.05). Results and Discussion: The parameter PKs per stimulus are summarised in Table 1.(Table Presented) The PK for U and NSRI were highest for all stimuli. Effect site concentrations of either Sevo or Remi alone were significantly worse predictors. BIS, SE, RE and CVI were significantly worse at predicting tolerance to the three painful stimuli, but similar to U and NSRI for SAS. SPI performed poorly overall. Conclusion: U and NSRI perform significantly better than EEG-derived parameters and single drug effect site concentrations in predicting tolerance to noxious stimuli. Therefore both U and NSRI could be useful parameters in anaesthetic practice.

Effects of caudal sufentanil supplemented with levobupivacaine on blocking spermatic cord traction response in pediatric orchidopexy

Caudal block is one of the most commonly used anesthetic techniques in subumbilical and genitourinary procedures. However, traditional administration of caudal levobupivacaine was inadequate on blocking peritoneal response during spermatic cord traction. The aim of this study was to evaluate whether the addition of caudal sufentanil to levobupivacaine provided better analgesia for children undergoing orchidopexy. Sixty-two patients, scheduled for right orchidopexy, received caudal block after induction. Group LS (n = 31) received levobupivacaine 0.25% 1 ml/kg plus sufentanil 0.5 μg/kg, and group L (n = 31) received levobupivacaine 0.25% 1 ml/kg only. HR or MAP fluctuation >20% or entropy increase >15% during spermatic cord traction was defined as inadequate anesthesia and was treated with increasing sevoflurane concentration. The number of children who needed sevoflurane rescue was counted, and postoperative side effects and quality of sleep were also recorded. There were no statistically significant differences between the two groups in age, weight, and duration of surgery. Two (6.45%) children in group LS required inspired sevoflurane rescue to block hemodynamic fluctuation during spermatic cord traction, as compared with 12 (38.71%) patients in group L (P < 0.001). At the time of exerting spermatic cord traction, the median HR was, respectively, 134 and 145 (P < 0.001); the corresponding response entropy (RE) and state entropy (SE) was 65 and 54, respectively, in group LS versus 76 and 65 in group L (P < 0.001). In pediatric orchidopexy, the addition of sufentanil to levobupivacaine for caudal blockade offers clinical benefit over levobupivacaine alone in blocking the spermatic cord traction response.

Impact of Entropy Monitoring on Volatile Anesthetic Uptake

Electroencephalogram-derived monitoring to assess anesthetic depth may allow more accurate hypnotic drug administration, resulting in decreased anesthetic drug consumption. The authors hypothesized that the use of M-Entropy monitoring (Datex-Ohmeda, Helsinki, Finland) is associated with reduced sevoflurane uptake (primary outcome) in patients undergoing major abdominal surgery. A total of 50 patients with an American Society of Anesthesiology score of II-III, scheduled for elective laparoscopic rectosigmoidectomy were randomized into two groups in this randomized controlled trial. In the control group, the target expiratory fraction of sevoflurane was adapted according to standard clinical practice. In the study group, the target expiratory fraction of sevoflurane was adapted to maintain state entropy values between 40 and 60. State entropy values were continuously recorded in both groups but were not available to the anesthesiologist in the control group. In both groups, patients were ventilated using the auto-control mode of the Zeus® (Dräger, Lübeck, Germany) respirator, which allows precise measurements of sevoflurane uptake. Sufentanil was administered using a target-controlled infusion system. Demographics did not differ between groups. During the anesthesia maintenance phase, state entropy values were lower in the control group than the study group (P < 0.0001). Sevoflurane uptake was higher in the control group than the study group (5.2 ± 1.4 ml/h vs. 3.8 ± 1.5 ml/h; P = 0.0012). Three patients in the control group developed intraoperative hypotension compared with none in the study group (P = 0.03). Monitoring the depth of anesthesia using M-Entropy was associated with a significant reduction in sevoflurane uptake.

Entropic commensurate-incommensurate transition.

The equilibrium properties of a minimal tiling model are investigated. The model has extensive ground state entropy, with each ground state having a quasiperiodic sequence of rows. It is found that the transition from the ground state to the high temperature disordered phase proceeds through a sequence of periodic arrangements of rows, in analogy with the commensurate-incommensurate transition. We show that the effective free energy of the model resembles the Frenkel-Kontorova Hamiltonian, but with temperature playing the role of the strength of the substrate potential, and with the competing lengths not explicitly present in the basic interactions.

Entangled dilaton dyons

Einstein-Maxwell theory coupled to a dilaton is known to give rise to extremal solutions with hyperscaling violation. We study the behaviour of these solutions in the presence of a small magnetic field. We find that in a region of parameter space the magnetic field is relevant in the infra-red and completely changes the behaviour of the solution which now flows to an $AdS_2\times R^2$ attractor. As a result there is an extensive ground state entropy and the entanglement entropy of a sufficiently big region on the boundary grows like the volume. In particular, this happens for values of parameters at which the purely electric theory has an entanglement entropy growing with the area, $A$, like $A \log(A)$ which is believed to be a characteristic feature of a Fermi surface. Some other thermodynamic properties are also analysed and a more detailed characterisation of the entanglement entropy is also carried out in the presence of a magnetic field. Other regions of parameter space not described by the $AdS_2\times R^2$ end point are also discussed.

Permutation auto-mutual information of electroencephalogram in anesthesia

Objective. The dynamic change of brain activity in anesthesia is an interesting topic for clinical doctors and drug designers. To explore the dynamical features of brain activity in anesthesia, a permutation auto-mutual information (PAMI) method is proposed to measure the information coupling of electroencephalogram (EEG) time series obtained in anesthesia. Approach. The PAMI is developed and applied on EEG data collected from 19 patients under sevoflurane anesthesia. The results are compared with the traditional auto-mutual information (AMI), SynchFastSlow (SFS, derived from the BIS index), permutation entropy (PE), composite PE (CPE), response entropy (RE) and state entropy (SE). Performance of all indices is assessed by pharmacokinetic/pharmacodynamic (PK/PD) modeling and prediction probability. Main results. The PK/PD modeling and prediction probability analysis show that the PAMI index correlates closely with the anesthetic effect. The coefficient of determination R2 between PAMI values and the sevoflurane effect site concentrations, and the prediction probability Pk are higher in comparison with other indices. The information coupling in EEG series can be applied to indicate the effect of the anesthetic drug sevoflurane on the brain activity as well as other indices. The PAMI of the EEG signals is suggested as a new index to track drug concentration change. Significance. The PAMI is a useful index for analyzing the EEG dynamics during general anesthesia.

Preoperative pregabalin does not reduce propofol ED50: a randomized controlled trial

In many studies, gabapentinoids, such as pregabalin, have been shown to reduce preoperative anxiety. This anxiolysis is often accompanied by sedation, one of the most frequent side effects of pregabalin. We hypothesized that pregabalin taken preoperatively could reduce propofol requirements for induction of general anesthesia. A randomized double-blind placebo-controlled trial was conducted after approval by the local ethics committee. Fifty women aged 18-40 yr, American Anesthesiologists Society physical status I and II, and scheduled to undergo elective laparoscopic gynecologic procedures were enrolled after written consent. Treatment group patients were given pregabalin 150 mg po one hour before surgery while patients in the control group received a placebo. The primary outcome was the propofol dose required to achieve a targeted anesthetic depth in 50% of the population, i.e., effective dose (ED)50. The ED50 was estimated using Dixon's up-and-down methodology. The targeted anesthetic depth was defined based on predetermined entropy monitoring values (State Entropy [SE] < 50 and Response Entropy [RE]-SE < 10). As a secondary outcome, we tested if pregabalin reduced pre-induction anxiety levels which were measured on a 0-100 scale. The propofol ED50 was not statistically different between the pregabalin group (mean 1.33 mg·kg(-1); 95% confidence interval [CI] 1.23 to 1.43) vs the placebo group (mean 1.37 mg·kg(-1); 95% CI 1.28 to 1.46); P = 0.19. Also, pre-induction anxiety level was not different between groups (median 31; interquartile range [IQR] [10-52] vs median 42; IQR [4-71], respectively; P = 0.41). Preoperative pregabalin does not reduce propofol requirements in a population of healthy young women undergoing laparoscopic gynecologic procedures. This study failed to show a pre-induction anxiolytic effect of pregabalin in such a population. This trial was registered at www.clinicaltrials.gov (NCT01158859).

Monitoring of Sedation during Neuroaxial Blockade

Study objective: The arousal state changes during spinal anesthesia. It is not clear if BIS and others devices could monitor the induced neuroaxial blockade sedation. Our objective was evaluate BIS and entropy values when spinal anesthesia is done. Design: We developed a prospective study. Patients: 40 patients were included in this study, ASA I-III, over 60 years old, undergoing spinal anesthesia, without premedication scheduled for orthopedics procedures. Intervention: Spinal anesthesia was performed with the unseated volunteer in the lateral decubitus position with a 25-gauge Whitacre needle at L2-L3 space, andanesthesia was done with 12 mg of 0.5% hyperbaric bupivacaine. Patients were positioned supine for 5 min after spinal anesthesia. Measurements: Observer’s Assessment of Alertness/Sedation OAA/S, response (RE) and state entropy (SE) and BIS, and standard hemodynamic measures. Main results: Statistical analysis were performed by Wilcoxon test or ANOVA, p 0.05). Conclusions: The spinal anesthesia decreased the cortical activity and these were founded by OAA/S scale and depth anesthetics monitors. OAA/S was a more sensitive value of this induced sedation. BIS and RE showed a better correlation with OAA/S scale than SE.

Entropy-guided end-tidal desflurane concentration during living donor liver transplantation

Background:The three phases of living donor liver transplantation (LDLT) represent different liver conditions. The aim is to study the required end-tidal desflurane concentration (ET-Des) guided with entropy monitoring for the depth of anesthesia.Methods:After the Ethics and Research Committee approval, 40 patients were included in this prospective study. Anesthesia was maintained with Desflurane-O2-air. State entropy (SE) and Response entropy (RE) were kept between 40 and 60.Results:Age and Model for End-stage Liver Disease (MELD) score were 45±10 years and 15.43±3.92, respectively. ET-Des were significantly lower in the anhepatic phase (2.8±0.4%) than in the pre-anhepatic and neohepatic phases (3.3±0.3%, 3.47±0.3%, respectively, P<0.001). The SE and RE for pre-anhepatic, anhepatic, and neohepatic phases were (45.6±3.7, 47.4±3.2), (44.7±2.1, 46.4±2.04), and (46.1±3.3, 47.9±3.3), respectively, with no significant changes between the phases, P > 0.05. Total operative time was 651±88 minutes, and for each phase it was 276±11, 195±55, and 191±24 minutes, respectively. Significant changes were found in hemoglobin g/dl and hematocrit % between the three phases (10.28±1.5, 30.48±4.3), (9.45±1.34, 28.36±4.1), and (8.88±1.1, 26.63±3.5), P<0.05. The heart rate and mean blood pressures were stable despite the cardiac index demonstrated a significant reduction during the anhepatic phase (2.99±0.22) when compared to the pre-anhepatic and neohepatic phases (3.60±0.29) and (4.72±0.32), respectively, (P<0.05). There was a significant correlation between CI and ET-Des% (r=0.604, P<0.05).Conclusion:Inhalational anesthetic requirements differed from one phase to another during LDLT, with requirements being the least during the anhepatic phase. Monitoring of the anesthesia depth was required, to avoid excess administration, which could compromise the hemodynamics before the critical time of reperfusion.

The effect of dexmedetomidine continuous infusion as an adjuvant to general anesthesia on sevoflurane requirements: A study based on entropy analysis

Background:Dexmedetomidine, a α2 agonist as an adjuvant in general anesthesia, has anesthetic and analgesic-sparing property.Aims:To evaluate the effect of continuous infusion of dexmedetomidine alone, without use of opioids, on requirement of sevoflurane during general anesthesia with continuous monitoring of depth of anesthesia by entropy analysis.Materials and Methods:Sixty patients were randomly divided into 2 groups of 30 each. In group A, fentanyl 2 mcg/kg was given while in group B, dexmedetomidine was given intravenously as loading dose of 1 mcg/kg over 10 min prior to induction. After induction with thiopentone in group B, dexmedetomidine was given as infusion at a dose of 0.2-0.8 mcg/kg. Sevoflurane was used as inhalation agent in both groups. Hemodynamic variables, sevoflurane inspired fraction (FIsevo), sevoflurane expired fraction (ETsevo), and entropy (Response entropy and state entropy) were continuously recorded. Statistical analysis was done by unpaired student's t-test and Chi-square test for continuous and categorical variables, respectively. A P-value < 0.05 was considered significant.Results:The use of dexmedetomidine with sevoflurane was associated with a statistical significant decrease in ETsevo at 5 minutes post-intubation (1.49 ± 0.11) and 60 minutes post-intubation (1.11 ±0.28) as compared to the group A [1.73 ±0.30 (5 minutes); 1.68 ±0.50 (60 minutes)]. There was an average 21.5% decrease in ETsevo in group B as compared to group A.Conclusions:Dexmedetomidine, as an adjuvant in general anesthesia, decreases requirement of sevoflurane for maintaining adequate depth of anesthesia.

Reduced sevoflurane consumption in cirrhotic compared to non-cirrhotic patients undergoing major hepatic surgery

BackgroundThere is evidence in literature that chronic hepatic patients need less anesthesia compared with healthy ones. Liver cirrhosis leads to a reduction in liver mass and hepatic blood flow with an effect on drug clearance and cardiovascular stability.AimTo evaluate sevoflurane consumption during entropy monitored general anesthesia in cirrhotic and non-cirrhotic patients during transition from consciousness to unconsciousness and throughout the procedure of major hepatic surgical procedures.Patients and methodsForty patients scheduled for major hepatic resection at the National Liver Institute, Menofiya University, Egypt, were studied prospectively and randomized into two equal groups. Group I (n. 20) cirrhotic patients (Child Pugh Grade A) with focal lesion, Group II (n. 20) healthy live liver donors undergoing major hepatectomies. Sevoflurane inhalational concentration was adjusted to achieve a state and response entropy of 40–60, and when RE increases 5–10 units above SE; more intravenous analgesics were given.ResultsMean (SD) Sevoflurane consumption in Group II showed higher consumption 23.5 (3.23) ml, compared to Group I 16 (2.19) ml. Mean (SD) sevoflurane consumption after 4 and 6 h from induction also showed a lower value in Group I 10.7(1.94), 9(1.22) ml, than in Group II 17.2(1.69), 14.1(2.19) ml, respectively. Mean (SD) end tidal sevoflurane concentration was lower in Group I 1.4(0.12) after 2 h from induction than in Group II 1.7(0.11). After 4 and 6 h from induction Group I demonstrated a lower value compared to Group II (P < 0.05.). Mean blood pressure, heart rate, urine output and CVP showed no significant changes during maintenance between the two groups.ConclusionThis study demonstrated that cirrhotic patients require less sevoflurane consumption and lower end-tidal concentration to maintain general anesthesia with entropy guidance. This could also have an important impact on the economic costs when applied on a larger scale.

Kinetics and thermodynamics of carbonation of a promising SOFC cathode material La0.5Ba0.5CoO3−δ (LBC)

This work examines the reactivity of a potentially promising SOFC cathode material, La0.5Ba0.5CoO3−δ (LBC), under CO2 atmosphere. Through a combination of different techniques – thermogravimetric analysis, ex situ XRD analyses of reacted products, and in situ XRD analysis – the reaction pathway and kinetics for LBC carbonation is investigated. The thermodynamic phase boundary for carbonate formation in the LBC–CO2 system has been generated and fundamental thermodynamic parameters – the standard state enthalpy (ΔH°) and the standard state entropy (ΔS°) – are determined.

Landauer-Büttiker Formula and Schrödinger Conjecture

We study the entropy flux in the stationary state of a finite one-dimensional sample \({\mathcal{S}}\) connected at its left and right ends to two infinitely extended reservoirs \({\mathcal{R}_{l/r}}\) at distinct (inverse) temperatures \({\beta_{l/r}}\) and chemical potentials \({\mu_{l/r}}\) . The sample is a free lattice Fermi gas confined to a box [0, L] with energy operator \({h_{\mathcal{S}, L}= - \Delta + v}\) . The Landauer-Büttiker formula expresses the steady state entropy flux in the coupled system \({\mathcal{R}_l + \mathcal{S} + \mathcal{R}_r}\) in terms of scattering data. We study the behaviour of this steady state entropy flux in the limit \({L \to \infty}\) and relate persistence of transport to norm bounds on the transfer matrices of the limiting half-line Schrödinger operator \({h_\mathcal{S}}\) .

Ab initiothermodynamics of intrinsic oxygen vacancies in ceria

Nonstoichiometric ceria(CeO${}_{2\ensuremath{-}\ensuremath{\delta}}$) is a candidate reaction medium to facilitate two-step water splitting cycles and generate hydrogen. Improving upon its thermodynamic suitability through doping requires an understanding of its vacancy thermodynamics. Using density functional theory (DFT) calculations and cluster expansion-based Monte Carlo simulations, we have studied the high-temperature thermodynamics of intrinsic oxygen vacancies in ceria. The DFT$+U$ approach was used to get the ground state energies of various vacancy configurations in ceria, which were subsequently fit to a cluster expansion Hamiltonian to efficiently model the configurational dependence of energy. The effect of lattice vibrations was incorporated through a temperature-dependent cluster expansion. Lattice Monte Carlo simulations using the cluster expansion Hamiltonian were able to detect the miscibility gap in the phase diagram of ceria. The inclusion of vibrational and electronic entropy effects made the agreement with experiments quantitative. The deviation from an ideal solution model was quantified by calculating as a function of nonstoichiometry, (a) the solid state entropy from Monte Carlo simulations, and (b) Warren-Cowley short range order parameters of various pair clusters.

Statistical derivation of basic equations of diffusional kinetics in alloys with application to the description of diffusion of carbon in austenite

Basic equations of diffusional kinetics in alloys are statistically derived using the master equation approach. To describe diffusional transformations in substitution alloys, we derive the “quasi-equilibrium” kinetic equation that generalizes its earlier versions by taking possible “interaction renormalization” effects into account. For the interstitial alloys Me-X, we derive an explicit expression for the diffusivity D of an interstitial atom X. This expression notably differs from those used in previous phenomenological treatments. This microscopic expression for D is applied to describe the diffusion of carbon in austenite based on some simple models of carbon-carbon interaction. The results obtained enable us to make certain conclusions about the real form of these interactions and about the scale of the “transition state entropy” for diffusion of carbon in austenite.

On holographic entanglement entropy of charged matter

We study holographic entanglement entropy in the background of charged dilatonic black holes which can be viewed as holographic duals of certain finite density states of N=4 super Yang-Mills. These charged black holes are distinguished in that they have vanishing ground state entropy. The entanglement entropy for a slab experiences a second order phase transition as the thickness of the slab is varied, while the entanglement entropy for a sphere is a smooth function of the radius. This suggests that the second scale introduced by the anisotropy of the slab plays an important role in driving the phase transition. In both cases we do not observe any logarithmic violation of the area law indicative of hidden Fermi surfaces. We investigate how these results are affected by the inclusion of the Gauss-Bonnet term in the bulk gravitational action. We also observe that such addition to the bulk action does not change the logarithmic violation of the area law in the backgrounds with hyperscaling violation.

Thermochemistry of radicals formed by hydrogen abstraction from 1-butanol, 2-methyl-1-propanol, and butanal

We calculate the standard state entropy, heat capacity, enthalpy, and Gibbs free energy for 13 radicals important for the combustion chemistry of biofuels. These thermochemical quantities are calculated from recently proposed methods for calculating partition functions of complex molecules by taking into account their multiple conformational structures and torsional anharmonicity. The radicals considered in this study are those obtained by hydrogen abstraction from 1-butanol, 2-methyl-1-propanol, and butanal. Electronic structure calculations for all conformers of the radicals were carried out using both density functional theory and explicitly correlated coupled cluster theory with quasipertubative inclusion of connected triple excitations. The heat capacity and entropy results are compared with sparsely available group additivity data, and trends in enthalpy and free energy as a function of radical center are discussed for the isomeric radicals.

Statistical Transfer Matrix Study of the ±JMultileg Ising Ladders and Tubes

Finite temperature properties of symmetric $\pm J$ multileg Ising ladders and tubes are investigated using the statistical transfer matrix method. The temperature dependences of the specific heat and entropy are calculated. In the case of tubes, it is found that the ground state entropy shows an even-odd oscillation with respect to the number of legs. The same type of oscillation is also found in the ground state energy. On the contrary, these oscillations do not take place in ladders. From the temperature-dependence of the specific heat, it is found that the lowest excitation energy is 4J for even-leg ladders while it is 2J otherwise, The physical origin of these behaviors is discussed based on the structure of excitations.