Well-defined Regimes Research Articles

Perioperative association between c-reactive protein, pain catastrophizing and acute pain after total knee arthroplasty: A secondary analysis of two randomised trials.

Total knee arthroplasty is associated with an inflammatory response and high levels of pain in a subset of patients. Pain catastrophizing has been associated with acute postoperative pain. The association between these variables has not been investigated in an optimised fast-track setup including preoperative glucocorticoids. The aim of this study was, first, to investigate the correlation between the increase in postoperative c-reactive protein (CRP) and acute postoperative pain after total knee arthroplasty, and second, to investigate the correlation between the increase in CRP and preoperative pain catastrophizing. This study is a secondary analysis of data from 119 patients participating in two randomised controlled trials. Correlation analyses were performed for preoperative CRP and CRP increase at 24 and 48 h and pain during a well-defined mobilisation at 24 and 48 h after total knee arthroplasty. Additionally, correlation analyses were performed between CRP increase and pain catastrophizing using the pain catastrophizing scale. There was no correlation between preoperative CRP or postoperative CRP increase and pain at both 24 and 48 h. Analyses were similar when separated into high and low pain catastrophizers. There was no correlation between preoperative CRP or postoperative CRP increase and pain catastrophizing. There was no association between the postoperative CRP response and postoperative acute pain or pain catastrophizing in patients undergoing total knee arthroplasty in a well-defined multimodal fast-track regime including preoperative glucocorticoids. These results suggest that acute pain after knee arthroplasty is not reflected by CRP when applying preoperative glucocorticoids.

Hydrodynamic regimes modulate nitrogen fixation and the mode of diazotrophy in Lake Tanganyika

The factors that govern the geographical distribution of nitrogen fixation are fundamental to providing accurate nitrogen budgets in aquatic environments. Model-based insights have demonstrated that regional hydrodynamics strongly impact nitrogen fixation. However, the mechanisms establishing this physical-biological coupling have yet to be constrained in field surveys. Here, we examine the distribution of nitrogen fixation in Lake Tanganyika – a model system with well-defined hydrodynamic regimes. We report that nitrogen fixation is five times higher under stratified than under upwelling conditions. Under stratified conditions, the limited resupply of inorganic nitrogen to surface waters, combined with greater light penetration, promotes the activity of bloom-forming photoautotrophic diazotrophs. In contrast, upwelling conditions support predominantly heterotrophic diazotrophs, which are uniquely suited to chemotactic foraging in a more dynamic nutrient landscape. We suggest that these hydrodynamic regimes (stratification versus mixing) play an important role in governing both the rates and the mode of nitrogen fixation.

Resonant Elastic X-Ray Scattering of Antiferromagnetic Superstructures in EuPtSi_{3}.

We report resonant elastic x-ray scattering of long-range magnetic order in EuPtSi_{3}, combining different scattering geometries with full linear polarization analysis to unambiguously identify magnetic scattering contributions. At low temperatures, EuPtSi_{3} stabilizes type A antiferromagnetism featuring various long-wavelength modulations. For magnetic fields applied in the hard magnetic basal plane, well-defined regimes of cycloidal, conical, and fanlike superstructures may be distinguished that encompass a pocket of commensurate type A order without superstructure. For magnetic field applied along the easy axis, the phase diagram comprises the cycloidal and conical superstructures only. Highlighting the power of polarized resonant elastic x-ray scattering, our results reveal a combination of magnetic phases that suggest a highly unusual competition between antiferromagnetic exchange interactions with Dzyaloshinsky-Moriya spin-orbit coupling of similar strength.

Evaluation of FeCrNiMo coating Tribological performance produced through laser directed energy deposition sliding under biodegradable oils

Improving the performance of mechanical components and reducing machine energy consumption involves the correct selection of lubricants and their contact surfaces. The use of biodegradable hydraulic fluids along with less environmental impact surfaces is one example. In this sense, the following paper aims to analyze the behavior of mineral oil (HLP) and biodegradable oils (HEPR and HETG) submitted to a sliding with pins manufactured in PTFE and Al2O3 against a flat substrate coated with FeCrNiMo by the Laser Directed Energy Deposition (L-DED) process. Coatings by this replacement deposition process are proving to be a promising alternative in the replacement of hard chromium, a harmful material to human health. The slip tests were performed in a pin-on-disk tribometer using different loads in order to assess lubrication and wear regimes. In the tests, the average of the friction coefficients (μ) obtained was μHETG = 0.072, μHLP = 0.026 and μHEPR = 0.011, besides well-defined lubrication regimes. In the wear analysis, it was observed that the highest concentrations of Zn and P additives, found in HEPR, reduced surface damage. The main wear mechanisms identified were scratching, microcracking, microploughing and detachment. Consistent with the results mentioned, the largest volume removed from the coating was with the use of HETG vegetable oil, about 41% more than HEPR.

Strategies for accessing the multipulse regime of mode-locked fiber lasers

Important ongoing research on mode-locked fiber lasers aims at developing new types of multisoliton regimes, such as soliton molecules, molecular complexes, or soliton crystals. The on-demand generation of such multipulse structures is a major challenge, whereas experiments generally involve a tedious trial-and-error adjustment of the laser parameters. Here we present an approach based on a gradual and calibrated adjustment of the system configuration, which employs efficient parameter routes to reach well-defined multipulse regimes. Our numerical simulations show that once the mode-locking threshold is reached, we can adjust the laser parameters gradually to force the evolution of the laser dynamics towards multipulse structures with fewer distortion in their intensity profiles, which are accessible at reduced pump power levels.

Rainfall regimes in Sri Lanka

ABSTRACT Understanding spatio-temporal variation in rainfall is important to water resources planning and management activities. Empirical orthogonal function (EOF) analysis and harmonic analysis are considered state-of-the-art techniques for analysing rainfall variability. This study considered monthly rainfall data from 18 principal stations and 21 secondary stations in Sri Lanka. K-means clustering was applied for identifying rainfall regimes. Rotated EOF analysis provided four key factors related to climate seasons of which the first two factors were more prominent, explaining more than 80% of the total variance. Harmonic analysis showed that northeastern and southwestern parts of the country possess strong annual and semi-annual variation, respectively explaining 90% of the total variance. Both EOF and harmonic analysis can be considered effective tools for identifying rainfall characteristics. However, harmonic analysis results successfully identified seven well-defined rainfall regime characteristics, which could be explained using tendency in data, amplitude, phase angle, and seasonal contribution.

Over Time and Space: Hybrid Rangeland Governance in Amdo Tibet

Abstract Hybrid land governance, mosaics, polycentrism have become ways to describe contemporary rangeland settings - ways of responding to uncertainties through flexible institutions, overlapping boundaries and an assembled, plural bricolage of practices. However, this is frequently thought to be recent, often arising from more formal, regulated systems, whether state, private or communal, and with well-defined land tenure regimes. This paper argues that hybridity (in various forms) has always been present in Amdo Tibet, despite the political changes over time and space. Hybridity is a necessary response to uncertainty and central to the utilisation of variable resources, which is the core strategy of pastoralism. Yet the form of hybridity varies as it must be constructed in particular historical circumstances, constrained by political economic conditions between the feudal, collectivist, liberalised eras. Today's hybridity - and so contemporary rangeland use and management strategies - must be understood in this historical context, as an accretion of practices and strategies that have emerged over different eras.

Perioperative changes in fluid distribution and haemodynamics in acute high-risk abdominal surgery

BackgroundUnderstanding the pathophysiology of fluid distribution in acute high-risk abdominal (AHA) surgery is essential in optimizing fluid management. There is currently no data on the time course and haemodynamic implications of fluid distribution in the perioperative period and the differences between the surgical pathologies.MethodsSeventy-three patients undergoing surgery for intestinal obstruction, perforated viscus, and anastomotic leakage within a well-defined perioperative regime, including intraoperative goal-directed therapy, were included in this prospective, observational study. From 0 to 120 h, we measured body fluid volumes and hydration status by bioimpedance spectroscopy (BIA), fluid balance (input vs. output), preload dependency defined as a > 10% increase in stroke volume after preoperative fluid challenge, and post-operatively evaluated by passive leg raise.ResultsWe observed a progressive increase in fluid balance and extracellular volume throughout the study, irrespective of surgical diagnosis. BIA measured variables indicated post-operative overhydration in 36% of the patients, increasing to 50% on the 5th post-operative day, coinciding with a progressive increase of preload dependency, from 12% immediately post-operatively to 58% on the 5th post-operative day and irrespective of surgical diagnosis. Patients with overhydration were less haemodynamically stable than those with normo- or dehydration.ConclusionDespite increased fluid balance and extracellular volumes, preload dependency increased progressively during the post-operative period. Our observations indicate a post-operative physiological incoherence between changes in the extracellular volume compartment and inadequate physiological preload control in patients undergoing AHA surgery. Considering the increasing overhydration during the observational period, our findings show that an indiscriminate correction of preload dependency with intravenous fluid bolus could lead to overhydration.Trial registration clinicaltrials.gov. (NCT03997721), Registered 23 May 2019, first participant enrolled 01 June 2019.

Equilibrium and non-equilibrium regimes in the learning of restricted Boltzmann machines* *This article is an updated version of: Decelle A, Furtlehner C and Seoane B 2021 Equilibrium and non-equilibrium regimes in the learning of restricted Boltzmann machines Advances in Neural Information Processing Systems vol 34 ed M Ranzato, A Beygelzimer, Y Dauphin, P S Liang and J Wortman Vaughan (New

Training restricted Boltzmann machines (RBMs) have been challenging for a long time due to the difficulty of precisely computing the log-likelihood gradient. Over the past few decades, many works have proposed more or less successful training recipes but without studying the crucial quantity of the problem: the mixing time, i.e. the number of Monte Carlo iterations needed to sample new configurations from a model. In this work, we show that this mixing time plays a crucial role in the dynamics and stability of the trained model, and that RBMs operate in two well-defined regimes, namely equilibrium and out-of-equilibrium, depending on the interplay between this mixing time of the model and the number of steps, k, used to approximate the gradient. We further show empirically that this mixing time increases with the learning, which often implies a transition from one regime to another as soon as k becomes smaller than this time. In particular, we show that using the popular k (persistent) contrastive divergence approaches, with k small, the dynamics of the learned model are extremely slow and often dominated by strong out-of-equilibrium effects. On the contrary, RBMs trained in equilibrium display faster dynamics, and a smooth convergence to dataset-like configurations during the sampling. Finally, we discuss how to exploit in practice both regimes depending on the task one aims to fulfill: (i) short k can be used to generate convincing samples in short learning times, (ii) large k (or increasingly large) is needed to learn the correct equilibrium distribution of the RBM. Finally, the existence of these two operational regimes seems to be a general property of energy based models trained via likelihood maximization.

Land tenure drives Brazil’s deforestation rates across socio-environmental contexts

Many tropical forestlands are experiencing changes in land-tenure regimes, but how these changes may affect deforestation rates remains ambiguous. Here, we use Brazil’s land-tenure and deforestation data and quasi-experimental methods to analyze how six land-tenure regimes (undesignated/untitled, private, strictly-protected and sustainable-use protected areas, indigenous, and quilombola lands) affect deforestation across 49 spatiotemporal scales. We find that undesignated/untitled public regimes with poorly defined tenure rights increase deforestation relative to any alternative regime in most contexts. The privatization of these undesignated/untitled lands often reduces this deforestation, particularly when private regimes are subject to strict environmental regulations such as the Forest Code in Amazonia. However, private regimes decrease deforestation less effectively and less reliably than alternative well-defined regimes, and directly privatizing either conservation regimes or indigenous lands would most likely increase deforestation. This study informs the ongoing political debate around land privatization/protection in tropical landscapes and can be used to envisage policy aligned with sustainable development goals.

Geometric bounds on the power of adiabatic thermal machines.

We analyze the performance of slowly driven meso- and microscale refrigerators and heat engines that operate between two thermal baths with a small temperature difference. Using a general scaling argument, we show that such devices can work arbitrarily close to their Carnot limit only if heat leaks between the baths are fully suppressed. Their power output is then subject to a universal geometric bound that decays quadratically to zero at the Carnot limit. This bound can be asymptotically saturated in the quasistatic limit if the driving protocols are suitably optimized and the temperature difference between the baths goes to zero with the driving frequency. These results hold under generic conditions for any thermodynamically consistent dynamics admitting a well-defined adiabatic-response regime and a generalized Onsager symmetry. For illustration, we work out models of a qubit-refrigerator and a coherent charge pump operating as a cooling device.

Gluon quasiparticles and the CGC density matrix

We revisit and extend the calculation of the density matrix and entanglement entropy of a color glass condensate (CGC) by including the leading saturation corrections in the calculation. We show that the density matrix is diagonal in the quasiparticle basis, where it has the Boltzmann form. The quasiparticles in a wide interval of momenta behave as massless two-dimensional bosons with the temperature proportional to the typical semihard scale $T={Q}_{s}/\sqrt{{\ensuremath{\alpha}}_{s}{N}_{c}}$. Thus, the semihard momentum region ${Q}_{s}<k<{Q}_{s}/\sqrt{{\ensuremath{\alpha}}_{s}{N}_{c}}$ arises as a well-defined intermediate regime between the perturbatively hard momenta and the nonperturbative soft momenta $k<{Q}_{s}$ in the CGC description of a hadronic wave function.

Study on the flow-induced vibration of a two-tandem cylinder system in rigid body motion

The flow-induced vibration (FIV) of a cylinder cluster is often observed in subsea pipelines and marine risers. The motion of the cylinder clusters was often modeled as the equation of motion of a particle, which has ignored the torsion freedom. Hence, the answers to the following questions are still unavailable—what are the impacts of torsion on the FIV of a cylinder cluster? Does torsional freedom facilitate the development of new features in FIV? In the present work, the FIV of a two-tandem cylinder system was numerically studied under the consideration of torsional freedom. It was found that six well-defined regimes were formed in the FIV of the cylinder system with the increase in the reduced velocity. The formation of different regimes mainly occurred by the accouplement of two frequencies—the vortex shedding frequency and the natural frequency of the cylinder system. A quirky low frequency dominated the cross-flow vibration at some reduced velocities, significantly magnifying the cross-flow vibration and the torsional vibration. The two cylinders acted as two feet treading water alternatively, enabling the cylinder system to move further on one side at such low frequencies. The characteristics of the amplitudes and frequency responses vs Ur* were qualitatively similar when the stiffness ratio k* was in the range of 10 ≤ k* ≤ 50, where Ur* was the torsional reduced velocity which was defined by the uniform velocity U divided torsional natural frequency frn and diameter of the cylinder D.

Amlexanox and Forskolin Prevents Isoproterenol-Induced Cardiomyopathy by Subduing Cardiomyocyte Hypertrophy and Maladaptive Inflammatory Responses.

Chronic catecholamine stress (CCS) induces the occurrence of cardiomyopathy—pathological cardiac hypertrophy (PCH), which is characterized by left ventricular systolic dysfunction (LVSD). Recently, mounting evidence has implicated myocardial inflammation in the exacerbation of pathological cardiac remodeling. However, there are currently no well-defined treatment interventions or regimes targeted at both the attenuation of maladaptive myocardial hypertrophy and inflammation during CCS to prevent PCH. G protein-coupled receptor kinase 5 (GRK5) and adenylyl cyclases (ACs)-cAMP mediates both cardiac and inflammatory responses. Also, GRK5 and ACs are implicated in stress-induced LVSD. Herein, we aimed at preventing PCH during CCS via modulating adaptive cardiac and inflammatory responses by inhibiting GRK5 and/or stimulating ACs. Isoproterenol-induced cardiomyopathy (ICM) was modeled using 0.5 mg/100 g/day isoproterenol injections for 40 days. Alterations in cardiac and inflammatory responses were assessed from the myocardia. Similarities in the immunogenicity of cardiac troponin I (cTnI) and lipopolysaccharide under CCS were assessed, and Amlexanox (35 μM/ml) and/or Forskolin (10 μM/ml) were then employed in vitro to modulate adaptive inflammatory responses by inhibiting GRK5 or activating ACs-cAMP, respectively. Subsequently, Amlexanox (2.5 mg/100 g/day) and/or Forskolin (0.5 mg/100 g/day) were then translated into in vivo during CCS to modulate adaptive cardiac and inflammatory responses. The effects of Amlexanox and Forskolin on regulating myocardial systolic functions and inflammatory responses during CCS were ascertained afterward. PCH mice had excessive myocardial hypertrophy, fibrosis, and aggravated LVSD, which were accompanied by massive CD68+ inflammatory cell infiltrations. In vitro, Forskolin-AC/cAMP was effective than Amlexanox-GRK5 at downregulating proinflammatory responses during stress; nonetheless, Amlexanox and Forskolin combination demonstrated the most efficacy in modulating adaptive inflammatory responses. Individually, the translated Amlexanox and Forskolin treatment interventions were ineffective at subduing the pathological remodeling and sustaining cardiac function during CCS. However, their combination was potent at preventing LVSD during CCS by attenuating maladaptive myocardial hypertrophy, fibrosis, and inflammatory responses. The treatment intervention attained its potency mainly via Forskolin-ACs/cAMP-mediated modulation of cardiac and inflammatory responses, coupled with Amlexanox inhibition of GRK5 mediated maladaptive cascades. Taken together, our findings highlight the Amlexanox and Forskolin combination as a potential therapeutic intervention for preventing the occurrence of pathological cardiac hypertrophy during chronic stress.

Predicting bone remodeling using a mechano-biological mathematical model combined with a natural neighbor meshless method

Bone tissue perceives certain mechanical stimuli, adapting its structure to a loading scenario through bone remodeling. Thanks to this ability, bone's functions of support and protection are assured. The mechanical response of bone is computationally reproduced in this work with a new bone remodeling model. Through a mechanobiological approach, the model includes two types of bone cells (i.e. osteoclasts and osteoblasts), describing its functioning and interaction with new sets of parameters. Mechanical stimulation induces a response by bone cells that ultimately is translated into variations of bone's apparent density and other mechanical properties by applying a material phenomenological law. The new algorithm here proposed is for the first time combined with an estabilished meshless method (Natural Neighbor Radial Point Interpolation Method), taking advantage of its features for biomedical applications. As a preliminary study, a two-dimensional bone patch is analyzed. A first study is performed to find the best parameters of NNRPIM for this type of simulation. Then, starting from a uniform bone distribution, a well-defined loading regime is imposed to the bone patch. Results revealed the expected bone adaption, attaining an optimized trabecular structure that reflects the orientation of the applied loads.

Role of surface diffusion in formation of unique reactivity for graphite oxidation: Time-resolved measurements in a pulsed diffusion reactor

Quantification of oxidation kinetics is essential to develop graphitic materials for diverse applications: from refractories found in gas-cooled nuclear reactors to catalysts needed for chemical manufacturing. Using well-defined highly oriented pyrolytic graphite, low-pressure isotopic transient experiments combined with controlled annealing periods are used to resolve the role of surface diffusion and quantify oxidation kinetics with nanomole-precision. We observe an unexpected increase in reactivity following annealing which is explained by the role of surface diffusion increasing the probability for trapping mobile oxygen at more reactive edge sites. Here, the locus of adsorption and spillover to the basal plane is distinct from the trapping location creating a more active oxygen species. Isotopic products reflect the population dynamics of oxygen added at the edge and surface diffusion that relocates basal plane oxygen to more reactive edge sites. Since this process proceeds in parallel with direct oxidation reactions, it is not likely to be observed using steady-state or conventional ‘bulk’ characterization techniques. Our unique time-resolved non-equilibrium measurement in a well-defined transport regime, enables observation of three distinct behaviors: short-term deactivation due to the balance of rates in oxygen supply/product formation, reactivity increases due to surface diffusion and longer-term reactivity increase with oxygen accumulation.

Scrambling and Lyapunov exponent in spatially extended systems

Scrambling of information in a quantum many-body system, quantified by the out-of-time-ordered correlator (OTOC), is a key manifestation of quantum chaos. A regime of exponential growth in the OTOC, characterized by a Lyapunov exponent, has so far mostly been observed in systems with a high-dimensional local Hilbert space and in weakly-coupled systems. Here, we propose a general criterion for the existence of a well-defined regime of exponential growth of the OTOC in spatially extended systems with local interactions. In such systems, we show that a parametrically long period of exponential growth requires the butterfly velocity to be much larger than the Lyapunov exponent times a microscopic length scale, such as the lattice spacing. As an explicit example, we study a random unitary circuit with tunable interactions. In this model, we show that in the weakly interacting limit the above criterion is satisfied, and there is a prolonged window of exponential growth. Our results are based on numerical simulations of both Clifford and universal random circuits supported by an analytical treatment.

The influence of a slider gap in the beam\u2013slider structure with an MFC element on energy harvesting from the system: experimental case

A passively self-tuning resonator configuration is presented in this study. Under certain operating conditions, a self-resonating system has the capability to passively adjust dynamical characteristics until the whole system becomes resonant. A clamped–clamped beam with an attached mass sliding along the beam and a slight gap that, under a harmonic input excitation and well-defined operating regime, can lead to the increase in voltage amplitude generated by the piezo-harvester attached to this structure may be an example of such a system. Taking into account such behavior of the system, the paper is focused on determining the distributed-parameters of the electromechanical system versus a different slider position on the beam in modal coordinates. The obtained simulation results, considering the homogenous model of an MFC element for the desired slider locations, showed how the width of the gap between the slider and the beam additionally influences the voltage generated by the piezo-harvester. Experimental tests carried out on the real stand with an EHE301 module and the designed SSHI interface circuit allowed to verify the numerical results and also showed the influence on the resistive load connected to the system for an improvement of the considered energy harvesting system parameters.

Sequence segregation in the melt and viscoelasticity of thermotropic liquid crystalline polymer. A rheo-X-ray scattering study

The influence of shear rate on the monomeric sequence segregation of molten thermotropic random copolyester was investigated in-situ using wide-angle X-ray scattering, and the microstructure was correlated with the viscoelastic properties. The X-ray pattern of the aligned macromolecules exhibited the 002 reflection in the melt, which confirmed periodicity along the polymer chains. The azimuthal spread of the 002 reflection is a measure of the degree of longitudinal register of neighboring chains. Increasing the shear rate increased the degree of macromolecular alignment, as measured by P‾2, the order parameter, and the azimuthal spread of the 002 reflection was reduced indicating the increase of the degree of longitudinal register. Small-strain oscillatory shear demonstrated that the monomeric sequence segregation appears to act as transient (physical) crosslinks, the liquid crystalline phase exhibited unusual elasticity and exhibited a well-defined rubber-like regime where G’>>G”. Hence, the van-Gurp-Palmen plot displayed a minimum. The presence of segregated sequences in the melt explains the unusual crystallinity in the random copolymer, the predominantly elastic behavior in the melt, and enables tuning the physical properties by controlling the microstructure.

Moulding of micropatterned nanocellulose films and their application in fluid handling

HypothesisWell-controlled micropatterned nanocellulose films are able to be fabricated via spray coating onto a micropatterned impermeable moulded surface. The micropattern size is able control the directionality of wicking fluid flow. ExperimentsUsing photolithography and etching techniques, silicon moulds with channel widths of 5–500 µm and depths of 6, 12 and 18 µm were fabricated. Micropatterned nanocellulose sheets were formed by spray coating nanofibre suspensions onto the moulds. We also investigate the effect the dimensions of these micropatterned nanocellulose films have on wicking fluids. FindingsMicropatterns were imparted on the surface of nanocellulose films which resulted in three well-defined regimes of conformation with the moulds: full, partial and no conformation. These regimes were driven by the aspect ratio (channel depth/width) of the moulds. Achieved channel widths and depths were compared to those possible with other micropattern fabrication techniques. The directionality of the wicking water droplets can be controlled with the micropatterned channel. Channels within the full conformation regime resulted in increased directionality of fluid flow compared with those not within this regime. This research demonstrates the industrially scalable process of spray coating has potential to serve as the foundation for a new generation of paper-based microfluidic devices.