Order Phase Research Articles

Attention in surgical phase recognition for endoscopic pituitary surgery: Insights from real-world data.

Attention in surgical phase recognition for endoscopic pituitary surgery: Insights from real-world data.

Canonical ensemble of a d -dimensional Reissner-Nordström black hole in a cavity

We construct the canonical ensemble of a d-dimensional Reissner-Nordström black hole spacetime in a cavity surrounded by a heat reservoir through the Euclidean path integral formalism. The cavity radius R is fixed, and the heat reservoir is at a fixed temperature T and fixed electric charge Q. We use York’s approach to find the reduced action by imposing the Hamiltonian and Gauss constraints and the appropriate conditions to the Euclideanized Einstein-Maxwell action with boundary terms, and then perform a zero loop approximation so that the paths that minimize the action contribute to the partition function. We find that, for an electric charge smaller or equal than a critical saddle electric charge Qs, there are three solutions r+1, r+2, and r+3, such that r+1<r+2<r+3. The solutions r+1 and r+3 are stable within the ensemble, while r+2 is unstable. For an electric charge equal to Qs, the solution r+2 merges with r+1 and r+3 at a given specific temperature. For an electric charge larger than Qs, there is only one solution r+4, which can be seen as the merging of the r+1 and r+3 solutions, with r+4 being stable. Since the partition function is directly related to the free energy in the canonical ensemble, we read off the free energy and calculate the thermodynamic variables, namely the entropy, the thermodynamic electric potential, the thermodynamic pressure, and the mean energy. We investigate thermodynamic stability, which is controlled by the positivity of the heat capacity at constant area and electric charge, and show that the heat capacity is discontinuous at the electric charge Qs, signaling a turning point. We analyze the favorable states, examining the free energies of the stable black hole solutions and the free energy of electrically charged hot flat space, in order to check for possible first and second order phase transitions between the possible states. For instance, the two stable black hole solutions r+1 and r+3 are in competition between themselves, more specifically, for certain ensemble parameters there exists a first order phase transition from one solution to the other, and at the critical charge Qs this transition turns into a second order phase transition. We also compare the thermodynamic radius of zero free energy with the generalized Buchdahl bound radius, which do not match, and comment on the physical implications, such as the possibility of total gravitational collapse of the thermodynamic system. We study the limit of infinite cavity radius and find two possibilities, the Davies and the Rindler solutions. The Davies thermodynamic solution of electrically charged black holes in d=4 dimensions is recovered from the general d-dimensional canonical ensemble analysis. We obtain, in particular, the heat capacity given by Davies and the Davies point. The Rindler solution describes the black hole horizon as a Rindler horizon, and the boundary, which is at fixed temperature T provided by the reservoir, must have the necessary acceleration to reproduce the corresponding Unruh temperature. Going back to a cavity with finite radius we find that the three solutions mentioned above are related to the original York two Schwarzschild black hole solutions and to the two Davies solutions, with the middle unstable solution r+2 belonging simultaneously to the two sets of solutions. In this sense, York’s and Davies’ formalisms have been unified in our approach. In all instances we mention carefully the four-dimensional case, d=4, for which we accomplish new results, and study in detail all aspects of the five dimensional case, d=5. Published by the American Physical Society 2025

You reap what you sow: On the impact of nuclei morphology on seeded molecular dynamics simulations.

Seeded molecular dynamics represents an increasingly popular approach to investigate crystal nucleation via computer simulations. This method involves the insertion of crystalline seeds into the supercooled liquid phase (often over a range of temperatures or sizes) in order to measure their evolution in time. When dealing with the prototypical scenario of crystal nucleation from Lennard-Jones melts, these seeds are artificially constructed to be approximately spherical fcc nuclei. In addition, the order parameter used to monitor the time evolution of a seed is typically chosen as the number of crystal-like atoms within it-consistent with the tenets of classical nucleation theory. However, evidence suggests that these artificially constructed seeds might be rather different from the crystalline nuclei formed during unbiased molecular dynamics simulations. In particular, previous studies of Lennard-Jones crystallization indicate that non-spherical, as well as bcc, nuclei might be involved with the nucleation process. In this work, we assess the impact of the choice of the initial crystalline nuclei in the context of seeded molecular dynamics by directly comparing two different classes of seeds. Specifically, we consider either crystalline nuclei extracted from "brute force" nucleation trajectories ("unbiased seed") or artificially constructed fcc spherical nuclei ("constructed seeds"). We show that the properties of these two classes of seeds, most notably their committor probability distributions, are markedly different. We also discuss the importance of choosing an appropriate order parameter for seeded molecular dynamics simulations and the implications of our results in the context of estimating crystal nucleation rates via computer simulations.

Chiral symmetry breaking and restoration by helical magnetic fields in AdS/CFT

We study the effects of helical magnetic fields on chiral symmetry breaking within the AdS/QCD framework using the D3/D7-brane model. By analyzing the brane embeddings, we obtain three types of massless solutions, corresponding to three phases with different behavior in the dual field theory. From the study of quark condensates, free energy, and electric currents, we find that helical magnetic fields can counteract uniform-field-induced symmetry breaking, driving the system towards symmetry restoration. We also find an effect analog to the chiral magnetic effect whereby the current is parallel to the magnetic field. We further study the massive case, and find that the helical configuration is less effective in erasing the first order phase transition that is present in the case of a constant magnetic field.

Observation of time crystal in a spin maser system

Pair interaction potentials between atoms in a crystal are in general non-monotonic in distance, with a local minimum whose position gives the lattice constant of the crystal. A temporal analogue of this idea of crystal formation is still pending despite intensive studies on the time crystal phase. In a hybrid spin maser system with a time delay feedback, we report the observation of a time crystal induced by a retarded interaction with a characteristic time scale. This nonequilibrium phase features a self-sustained oscillation with an emergent frequency other than the intrinsic Larmor precession frequency of the spin maser system. It is shown that the amplitude of the oscillation is robust against perturbation, while its time phase randomly distributes from 0 to 2π for different realizations, a signature of spontaneous time translation symmetry breaking. This time crystal phase emerges only when the feedback strength exceeds a critical value, at which the system experiences a first order phase transition. Such a retarded interaction induced time crystal is closer to the idea of crystal, compared to other time crystal realizations.

First order phase transition in a two-dimensional superconductor

First order phase transition in a two-dimensional superconductor

Enhanced smectic ordering and blue phase formation in mixtures of cyanobiphenyls and cholesterol esters

ABSTRACT It has been found that in mixtures of nematic E7 and smectogenic cholesteryl oleyl carbonate (COC) the SmA – N* transition temperature is substantially (by ~20 K) increased, as compared with pure COC, at E7 concentrations around ~40 wt. %. Within the same concentration range, the isotropic transition is preceded by formation of blue phase (BP), with its maximum width of ~3.5 K clearly correlated to the increased thermal stability of the SmA phase. With other cholesterol esters or cyanobiphenyls (cholesteryl nonanoate and 5CB), this effect was either much weaker or not observed. The spectra of selective Bragg reflection of light (BRL) were measured in all characteristic sections of the mesophase temperature range, including the unwinding of the cholesteric helix on cooling towards SmA phase and changes in selective BRL characterising the blue phase. In the latter case, the measured λmax values were shown to be dependent both on the helical twisting power in the cholesteric phase and on the lattice size and orientation in the blue phase. In an attempt to increase the BP temperature stability, ferroelectric nanoparticles of BaTiO3 were added to the studied mixtures. The observed broadening of the BP temperature range was associated with accumulation of nanoparticles at disclination lines.

Magnetic ordering phase transition and abnormal brittleness in dilute Fe–Mn solid solution

Magnetic ordering phase transition and abnormal brittleness in dilute Fe–Mn solid solution

Using Contactless Interfacial Rheology to Probe Interfacial Mechanics for Compositional Ripening.

In this study, we investigate the impact of modifying colloid-colloid interactions on the rheological properties of a layer of poly(methyl methacrylate) PMMA colloids at a dodecane-water interface. Toluene is introduced into the oil phase in order to modify attractive interactions between colloids. We first make qualitative observations of water-in-oil emulsions undergoing compositional ripening, demonstrating how the addition of toluene modifies the evolution. Without toluene, water droplets finally "explode"; with the addition of toluene, they instead form connected colloidal structures. We secondly employ a novel contactless interfacial setup to probe the rheological properties of a PMMA colloid-laden water-dodecane interface, examining the effects of toluene addition. We find that the interface becomes significantly weaker and more flexible following addition of toluene, contrary to what one might expect for increasing interparticle attractions for high surface coverage interfaces.

Models of Machine Learning to Diagnose Chronic Kidney disease using a WEKA-based Classifier

In the present day, humans are confronted with a variety of diseases as a result of their lifestyle and the current environmental conditions. Therefore, it is crucial to identify and predict these diseases in their early phases in order to prevent their severe manifestations. Manually identifying maladies is a challenging task for physicians on a regular basis. Predicting chronic illnesses is the aim of this article. This goal is applicable through a state-of-the-art approach to classification correctly identifies people with chronic illnesses. Predicting maladies is also a difficult endeavor. Therefore, disease prediction is significantly influenced by data mining. To get data, a collection of disease symptoms, the individual's lifestyle, and information regarding medical consultations are considered in this general disease prediction. In conclusion, this paper analyzes that model with a variety of algorithms, including (Naiva Bayes) and (RF-Random Forest).

Accessing Universal Relations of Binary Neutron Star Waveforms in Massive Scalar-Tensor Theory.

We investigate how the quasiuniversal relations connecting tidal deformability with gravitational waveform characteristics and/or properties of individual neutron stars that were proposed in the literature within general relativity would be influenced in the massive Damour-Esposito-Farese-type scalar-tensor gravity. For this purpose, we systematically perform numerical relativity simulations of ∼120 binary neutron-star mergers with varying scalar coupling constants. Although only three neutron-star equations of state are adopted, a clear breach of universality can be observed in the datasets. In addition to presenting difficulties in constructing quasiuniversal relations in alternative gravity theories, we also briefly compare the impacts of non-general-relativity physics on the waveform features and those due to the first order or cross-over quantum chromodynamical phase transition.

Thermodynamics of s±-to-s++ transition in iron pnictides in the vicinity of the Born limit

Abstract To study the thermodynamic properties of the disorder-induced transition between s ± and s + + superconducting gap functions, we calculate the grand thermodynamic potential Ω in the normal and the superconducting states. An expression for the difference between the two, ΔΩ, is derived for a two-band model for Fe-based systems with nonmagnetic impurities. The disorder is considered in a T -matrix approximation within the multiband Eliashberg theory. In the vicinity of the Born limit near the s ± -to- s + + transition, we find two solutions obtained for opposite directions of the system’s evolution with respect to the impurity scattering rate. By calculating the change in entropy ΔS and the change in the electronic specific heat ΔC from ΔΩ, we show that such a hysteresis is not due to the time-reversal symmetry breaking state, but that it instead points to the first order phase transition (PT) induced by the nonmagnetic disorder. Based on the ΔΩ calculations, a phase diagram is plotted representing the energetically favorable s ± and s + + states and the transition between them. At finite temperature, a first order PT line there is limited by a critical end point. Above that point, the sharp s ± → s + + transition transforms into a crossover between s ± and s + + states.

The Role of First and Second Order Phase Transitions in MnCoGe-Based Compounds: Implications for Magnetic Refrigeration Technology

This review presents a comprehensive analysis of MnCoGe-based compounds and their potential for magnetic refrigeration applications, focusing on the phase transitions and magnetocaloric properties of these materials. MnCoGe-based alloys exhibit both first and second-order phase transitions, with first-order transitions delivering large magnetic entropy changes (ΔSM) but also suffering from thermal hysteresis. Second-order transitions, though offering smaller entropy changes, provide improved thermal stability and reduced hysteresis, making them suitable for continuous operation. Compositional tuning, through the addition of elements such as Si, Al, and Fe, has been shown to optimize the magnetocaloric performance of these materials, particularly by tailoring the transition temperature to practical levels. Performance evaluation highlights the significant cooling capacities of MnCoGe-based compounds, indicating their potential for energy-efficient and environmentally friendly magnetic refrigeration systems. The paper concludes with recommendations for future research, emphasizing the need for further optimization of material properties and the development of scalable synthesis methods for industrial applications.

Entanglement entropy and thermal phase transitions from curvature singularities

We study holographic entanglement entropy and revisit thermodynamics and confinement in the dilaton-gravity system. Our analysis focuses on a solvable class of backgrounds that includes AdS and linear dilaton spacetimes as particular cases, with some results extended to general warped metrics. A general lesson is that the behavior of the holographic theory is tied to the bulk curvature singularities. We find that a singular background is confining if and only if i) the singularity coincides with a boundary or ii) it is the linear dilaton. In the former case, for which the singularity cuts off spacetime, we demonstrate that both entanglement entropy and thermodynamics exhibit a first order phase transition. In the linear dilaton case we find instead that both entanglement entropy and thermal phase transitions are of second order. Additionally, along the process we thoroughly derive the radion effective action at quadratic order.

Adiabatic conversion of ALPs into dark photon dark matter

We introduce a mechanism by which a misaligned ALP can be dynamically converted into a dark photon in the presence of a background magnetic field. An abundance of non-relativistic ALPs will convert to dark photons with momentum of order the inhomogeneities in the background field; therefore a highly homogeneous field will produce non-relativistic dark photons without relying on any redshifting of their momenta. Taking hidden sector magnetic fields produced by a first order phase transition, the mechanism can reproduce the relic abundance of dark matter for a wide range of dark photon masses down to 10−13 eV.

Composition and structure evolution of LPSO phase in Mg-Gd-Y-Zn-Zr homogenised by pulsed current

ABSTRACT Here it was found that the homogenisation for rare earth magnesium alloy can be performed under pulsed current (422°C/10 min), which is superior to the traditional industry one (520°C/720 min). Because the pulsed homogenisation can promote atomic diffusion by conductivity difference between the Long Period Stacking Ordered (LPSO) phase and the α-Mg. The pulsed homogenisation can break the lamellar LPSO phase inside the grains and weaken element fluctuation.

Phases and phase transitions of U(1)×SU(2) symmetric holographic matter

The phase diagram and symmetry breaking patterns of a holographic CFT with U(1) × SU(2) symmetry are analyzed using the simplest holographic action, namely Einstein-Yang-Mills (YM) theory with a negative cosmological constant. This is relevant for both condensed matter and QCD applications. With a U(1) and an “isospin” chemical potential turned on, we determine all possible symmetry breaking patterns, which are associated to the condensation of spin-one order parameters. The possible IR asymptotics of the Einstein-YM solutions are derived analytically, both for 2+1 and 3+1 boundary dimensions. The competing solutions are then computed numerically, both at zero and non-zero temperature, from which the full three-dimensional phase diagram is determined. We find a surface of second order phase transitions that separate uncondensed and condensed phases. In some regions with a large fraction of charged to neutral degrees of freedom, the phase transition becomes first order.

The Importance of Bilayer Asymmetry in Biological Membranes: Insights from Model Membranes.

This mini-review intends to highlight the importance of bilayer asymmetry. Biological membranes are complex structures that are a physical barrier separating the external environment from the cellular content. This complex bilayer comprises an extensive lipid repertory, suggesting that the different lipid structures might play a role in the membrane. Interestingly, this vast repertory of lipids is asymmetrically distributed between leaflets that form the lipid bilayer. Here, we discuss the properties of the plasma membrane from the perspective of experimental model membranes, consisting of simplified and controlled in vitro systems. We summarize some crucial features of the exoplasmic (outer) and cytoplasmic (inner) leaflets observed through investigations using symmetric and asymmetric membranes. Symmetric model membranes for the exoplasmic leaflet have a unique lipid composition that might form a coexistence of phases, namely the liquid disordered and liquid order phases. These phase domains may appear in different sizes and shapes depending on lipid composition and lipid-lipid interactions. In contrast, symmetric model membranes for the cytoplasmic leaflet form a fluid phase. We discuss the outcomes reported in the literature for asymmetric bilayers, which vary according to lipid compositions and, consequently, reflect different intra- and inter-leaflet interactions. Interestingly, the asymmetric bilayer could show induced domains in the inner leaflet, or it could decrease the tendency of the outer leaflet to phase separation. If cells regulate the lipid composition of the plasma membrane, they can adjust the existence and sizes of the domains by tuning the lipid composition.

θ dependence of Tc in SU(2) Yang-Mills theory

We present an exploratory study to determine the confinement-deconfinement transition temperature at finite θ, Tc(θ), for the 4d SU(2) pure Yang-Mills theory. Lattice numerical simulations are performed on three spatial sizes NS = 24, 32, 48 with a fixed temporal size NT = 8. We introduce a non-zero θ-angle by the sub-volume method to mitigate the sign problem. By taking advantage of the universality in the second order phase transition and the Binder cumulant of the order parameter, the θ-dependence of Tc is determined to be Tc(θ)/Tc(0) = 1 − 0.16(2) (θ/π)2 − 0.03(4) (θ/π)4 up to θ ∼ 0.9 π. The reliability of the extrapolations in the sub-volume method is extensively checked. We also point out that the temperature dependence of the topological susceptibility should exhibit a singularity with the exponent for the specific heat.

Phase diagram of the J1−J2 Heisenberg second-order topological quantum magnet

Competing interactions in quantum magnets lead to a variety of emergent states, including ordered phases, nematic magnets, and quantum spin liquids. Among them, topological quantum magnets represent a promising platform to create topological excitations protected by the bulk many-body excitation gap. Here we establish the phase diagram of a breathing frustrated antiferromagnetic J1−J2-Heisenberg model, featuring both ordered states and a higher-order topological quantum magnet state. Using variational many-body methods based on neural network quantum states and tensor networks, we determine the existence of a first-order phase transition between stripe order and the topological quantum magnet and the second-order phase transition between the Néel order and quantum magnet phase, further corroborated by calculations of the many-body gap. Using an auxiliary fermion parton formalism, we show the emergence of topological spinon corner modes stemming from the breathing order parameter of the parent Heisenberg model. Our results establish the breathing frustrated square lattice Heisenberg model as a paradigmatic system to engineer topological quantum magnetism, as recently realized in Ti lattices at MgO. Published by the American Physical Society 2025