Order Transition Research Articles

Retos políticos de la radiodifusión en el escenario de la revolución digital

The traditional media are currently immersed in an accelerated structural change, driven by the irruption of Information and Communication Technologies (ICT), which cause the emigration of their audiences towards other forms or modalities of reception and consumption. The appearance and popularization of the so-called social networks in the framework (ICT) brings with it a set of challenges for traditional radios. Consequently, the objective of the research consisted of describing some political challenges of the radio in the scenario of the digital revolution, as a condition of possibility to stop its extension as mass media. To achieve the proposed objective, the phenomenological and hermeneutical methodology was used with a predominance of documentary sources in digital format, which were analyzed and discussed to draw up the conclusions of the study. The results obtained allow us to conclude that the Ecuadorian state does not establish the necessary political guidelines to carry out a systematized and orderly transition from analog to digital broadcasting, which implies a technological backwardness in terms of ICT in the country.

Disorder–Order Transition in Ga2O3 and Its Solid Solution with In2O3 upon Thermal Annealing

The local ordering in amorphous Ga2O3 and (In x Ga1−x )2O3 thin films on Si(111) and its change on crystallization upon annealing are investigated. Synchrotron‐based extended X‐ray absorption fine structure data, as probed across the Ga K‐edge in conjunction with a numerical implementation of the scattering process including multiple scattering events, provide detailed insights into the bonding character of the Ga cations. Bond lengths and coordination numbers indicate the preferential formation of GaO4 tetrahedrons in the amorphous binary and ternary solid solution at the absence of long‐range ordering. Upon annealing there is no tendency toward the formation of long‐range ordering for the ternary alloy, while the amorphous Ga2O3 film turns into monoclinic β‐Ga2O3 crystallites with both tetra‐ and octahedral coordination.

Dissipative Quantum Criticality as a Source of Strange Metal Behavior

The strange metal behavior, usually characterized by a linear-in-temperature (T) resistivity, is a still unsolved mystery in solid-state physics. It is often associated with the proximity to a quantum critical point (a second order transition at temperature T=0, leading to a broken symmetry phase) focusing on the related divergent order parameter correlation length. Here, we propose a paradigmatic shift, focusing on a divergent characteristic time scale due to a divergent dissipation acting on the fluctuating critical modes while their correlation length stays finite. To achieve a divergent dissipation, we propose a mechanism based on the coupling between a local order parameter fluctuation and electron density diffusive modes that accounts both for the linear-in-T resistivity and for the logarithmic specific heat versus temperature ratio CV/T∼log(1/T), down to low temperatures.

Kinetic Pathway of the Order–Order Transition from Hexagonally Packed Cylinder to Hexagonally Perforated Layer in Polystyrene-block-Poly(2-vinylpyridine) Using Time-Resolved 3D Transmission Electron Microtomography

The kinetic pathway of the order–order transition (OOT) from a hexagonally packed cylinder (HEX) to a hexagonally perforated layer (HPL) phase in polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) was studied using time-resolved three-dimensional transmission electron microtomography (3D-TEM). Our results revealed that this OOT proceeds via the nucleation and growth process. During the nucleation stage, the cylindrical domains transition from an initial metastable state at random positions owing to thermal fluctuation. Adjacent undulating cylindrical domains merge into wave-like structures to form perforations in hexagonal packing and act as nuclei. During the growth stage, after each nucleus exceeds the critical size, the neighboring intermediates coalesce into the HPL phase with AB-type stacking (P63/mmc space group). The coherency of the HPL orientation in the grain increased during OOT. Understanding the OOT kinetic pathway is useful for the morphological evolution of block copolymers and for designing suitable transition pathways to obtain ordered structures for diverse nanotechnology applications.

Topological interpretation for phase transitions of black holes

In this work, we develop a universal picture from topology in the thermodynamic parameters space to describe first order phase transitions of black holes. By employing an off-shell internal energy, we find two types of topological defects. The first is normal, describing black holes which move with a nonzero velocity and acceleration, in a central force field. The second type of defects are exotic: they are static in the space, not describing black holes but encoding information about first order transitions. For each defect, we assign a winding number and an inertial mass. By studying neutral and charged black holes in asymptotically anti-de Sitter space, we show that first order transitions can be viewed as once or twice interchange of winding numbers between black holes and the exotic defects, through wired action at a distance. This corresponds to the usual notion: a smaller black hole grows into a larger black hole or vice versa. However, our topological analysis illustrates that the transition can also be locally interpreted as virtual collisions between black holes and the exotic defects. In this interpretation, a smaller black hole first grows into a new exotic defect whereas an original exotic defect grows into a larger black hole. All the defects simply change their positions and momentums, rather than interchanging the winding numbers. Critical point of the transition can be extracted when all the defects meet in the parameters space. Certain quantities, such as the Jacobians and the velocities of normal defects show universal behaviors near the critical point.

Recognizing Human Activity of Daily Living Using a Flexible Wearable for 3D Spine Pose Tracking.

The World Health Organization recognizes physical activity as an influencing domain on quality of life. Monitoring, evaluating, and supervising it by wearable devices can contribute to the early detection and progress assessment of diseases such as Alzheimer's, rehabilitation, and exercises in telehealth, as well as abrupt events such as a fall. In this work, we use a non-invasive and non-intrusive flexible wearable device for 3D spine pose measurement to monitor and classify physical activity. We develop a comprehensive protocol that consists of 10 indoor, 4 outdoor, and 8 transition states activities in three categories of static, dynamic, and transition in order to evaluate the applicability of the flexible wearable device in human activity recognition. We implement and compare the performance of three neural networks: long short-term memory (LSTM), convolutional neural network (CNN), and a hybrid model (CNN-LSTM). For ground truth, we use an accelerometer and strips data. LSTM reached an overall classification accuracy of 98% for all activities. The CNN model with accelerometer data delivered better performance in lying down (100%), static (standing = 82%, sitting = 75%), and dynamic (walking = 100%, running = 100%) positions. Data fusion improved the outputs in standing (92%) and sitting (94%), while LSTM with the strips data yielded a better performance in bending-related activities (bending forward = 49%, bending backward = 88%, bending right = 92%, and bending left = 100%), the combination of data fusion and principle components analysis further strengthened the output (bending forward = 100%, bending backward = 89%, bending right = 100%, and bending left = 100%). Moreover, the LSTM model detected the first transition state that is similar to fall with the accuracy of 84%. The results show that the wearable device can be used in a daily routine for activity monitoring, recognition, and exercise supervision, but still needs further improvement for fall detection.

Climate change and macro-financial risks: financial policy responses for an orderly low-carbon transition

Climate-related financial policies (CRFPs) are needed to tame potential climate-related financial risks deriving from climate change and to finance the low-carbon transition. International engagement levels and CRFP adoption are currently too low to encourage an adequate low-carbon transition and protect the financial system from materializing climate risks. Therefore, greater global commitment is especially important as the COP27 will likely uphold the 1.5 ∘C targets while following the Intergovernmental Panel on Climate Change’s advice to keep global warming below 2 ∘C. Despite the recent rapid proliferation of the literature on climate-related financial policymaking, some important knowledge gaps remain. Additional investigation, particularly in financial disclosure and stress tests, climate-aligned macro-prudential policies aimed at financial capital, climate data availability, and new research approaches, is required to help decision-makers achieve orderly and swift decarbonization.

The constant forms: a ubiquitous and pragmatic ontogony

According to Etienne Souriau, ontology must be grasped in light of an ontogonic perspective in which future is to be rebuilt permanently as an act. We show that “constant forms” support Souriau’s aim that ontogony must be both ubiquitous and pragmatic. Firstly, the “constant forms” support Souriau’s ubiquitous ontogony which aims to escape the reification due to the “law of localization”. Secondly, as far as they are considered as “action template”, the “constant forms” support Souriau’s pragmatic ontogony according to which “existence is an act”. Thirdly, Souriau characterizes as “constant forms” the morphems on which is based his synaptic vision (as opposed to the ontic vision) which values the dynamical role of transitions in order to create a future as an act, as it is required by the criteria of pragmatic ontogony.

Phase diagram of mixed-dimensional anisotropic t−J models

We study the phase diagram of two different mixed-dimensional $t-J_z-J_{\perp}$-models on the square lattice, in which the hopping amplitude $t$ is only nonzero along the $x$-direction. In the first, bosonic, model, the spin exchange amplitude $J_{\perp}$ is negative and isotropic along the $x$ and $y$ directions of the lattice, and $J_z$ is isotropic and positive. The low-energy physics is characterized by spin-charge separation: the holes hop as free fermions in an easy-plane ferromagnetic background. In the second model, $J_{\perp}$ is restricted to the $x$-axis while $J_z$ remains isotropic and positive. The model is agnostic to particle statistics, and shows stripe patterns with anti-ferromagnetic N{\'e}el order at low temperature and high hole concentrations, in resemblance of the mixed-dimensional $t-J_z$ and $t-J$ models. At lower hole concentration, a very strong first order transition and hysteresis loop is seen extending to a remarkably high 14(1)% hole doping.

Multisideband interference structures observed via high-order photon-induced continuum-continuum transitions in argon

We report a joint experimental and theoretical study of a three-sideband (3-SB) modification of the reconstruction of attosecond beating by interference of two-photon transitions (RABBIT) setup. The 3-SB RABBIT scheme makes it possible to investigate phases resulting from interference between transitions of different orders in the continuum. Furthermore, the strength of this method is its ability to focus on the atomic phases only, independent of a chirp in the harmonics, by comparing the RABBIT phases extracted from specific SB groups formed by two adjacent harmonics. We verify earlier predictions that the phases and the corresponding time delays in the three SBs extracted from angle-integrated measurements become similar with increasing photoelectron energy. A variation in the angle dependence of the RABBIT phases in the three SBs results from the distinct Wigner and continuum-continuum coupling phases associated with the individual angular-momentum channels. A qualitative explanation of this dependence is attempted by invoking a propensity rule. Comparison between the experimental data and predictions from an $R$ matrix (close-coupling) with time dependence calculation shows qualitative agreement in most of the observed trends.

Deep learning techniques for the localization and classification of liquid crystal phase transitions

Deep Learning techniques such as supervised learning with convolutional neural networks and inception models were applied to phase transitions of liquid crystals to identify transition temperatures and the respective phases involved. In this context achiral as well as chiral systems were studied involving the isotropic liquid, the nematic phase of solely orientational order, fluid smectic phases with one-dimensional positional order and hexatic phases with local two-dimensional positional, so-called bond-orientational order. Discontinuous phase transition of 1st order as well as continuous 2nd order transitions were investigated. It is demonstrated that simpler transitions, namely Iso-N, Iso-N*, and N-SmA can accurately be identified for all unseen test movies studied. For more subtle transitions, such as SmA*-SmC*, SmC*-SmI*, and SmI*-SmF*, proof-of-principle evidence is provided, demonstrating the capability of deep learning techniques to identify even those transitions, despite some incorrectly characterized test movies. Overall, we demonstrate that with the provision of a substantial and varied dataset of textures there is no principal reason why one could not develop generalizable deep learning techniques to automate the identification of liquid crystal phase sequences of novel compounds.

Low information NMR data guided protein-peptide complex structure determination with MELDXMD.

About 40% of the protein-protein interactions are mediated through small peptide epitope. Knowledge of how a peptide or an intrinsically disordered protein fragment interact with a protein would widen of the understanding of gene regulation, transcription and finally drug discovery. However, the folding upon binding nature of majority of the peptide interacting partner, limits the ability of modeling tools to predict structures of such complexes. To address this problem, we show an integrative approach combining cost-effective NMR chemical shift data and physics based molecular simulations to determine structures of protein-peptide complexes. Here in this presentation, we demonstrate our approach for polypeptide complexes formed with the extraterminal (ET) domain of bromo and extraterminal domain (BET) proteins, which exhibit a high degree of binding plasticity. This system is particularly challenging as the binding process includes allosteric changes across the ET receptor upon binding, and the polypeptide binding partners can form different conformations (e.g., helices and hairpins) in the complex. In a blind study, the new approach successfully predicts bound-state structure, using only backbone chemical shift data, in excellent agreement with experimental structure. We show, this approach is successful on not only strongly interacting complexes, but also in the case of weak binder, this method has been successful. MELD+NMR also predicts relative binding affinities of different peptides, consistent with the experimental values. The hybrid MELD+NMR approach provides a powerful new tool for structural analysis of protein-polypeptide complexes involving disorder to order transitions upon complex formation which are not successfully modeled with most other complex predication methods including state of the art docking methods, providing 3D atomistic structures of complexes as well as their relative binding affinities.

Impact of Photoactive Monomer Location in Photoresponsive Block Copolymer/Ionic Liquid Solutions

By incorporating a photoactive moiety into a block polymer, the phase behavior can be controlled with light. Previous studies have looked at situating azobenzene, a common photoresponsive molecule, along the backbone of the polymer as a pendant group, and even as part of the solvent rather than as a comonomer. Here, we study the effect of the positioning of pendant azobenzene groups along the polymer backbone on the lower critical disorder–order transition of poly(methyl methacrylate)-block-poly(benzyl methacrylate) (PMMA-b-PBnMA, or MB) in the ionic liquid 1,3-dimethyl imidazolium bis(trifluoromethylsulfonyl)imide. Using small-angle X-ray scattering and ultraviolet (UV)-irradiated small-amplitude oscillatory shear rheology, the placement of azobenzene statistically along the benzyl methacrylate backbone (MBsA) is compared to locating it as a midblock between the PMMA and the PBnMA (MAB) or as an end block after the PBnMA (MBA). Two concentrations of polymer in the ionic solvent were studied, 35 and 50 wt %. At 35 wt %, MBsA microphase-separated at 60 °C, MBA at 100 °C, and followed by MAB at 120 °C, a trend that was repeated at 50 wt %. MBsA was the only polymer to order onto a lattice at 35 wt %, forming hexagonally close-packed spheres. Both MBsA and MBA formed hexagonally packed cylinders at 50 wt %. MBsA consistently ordered onto a lattice over the temperature range of interest, while MBA only did so at 50 wt %, and MAB remained disordered at both concentrations. MBsA was also the only sample of the three to successfully transition reversibly between order and disorder with light. Therefore, adjusting the location of the azobenzene units within the thermo- and photoresponsive polymer solution significantly changes the overall behavior of the solutions and the ability to control that behavior with light and temperature.

Accounting for the ultraviolet divergence in field-theoretic simulations of block copolymer melts.

This study examines the ultraviolet (UV) divergence in field-theoretic simulations (FTSs) of block copolymer melts, which causes an unphysical dependence on the grid resolution, Δ, used to represent the fields. Our FTSs use the discrete Gaussian-chain model and a partial saddle-point approximation to enforce incompressibility. Previous work has demonstrated that the UV divergence can be accounted for by defining an effective interaction parameter, χ=z∞χb+c2χb 2+c3χb 3+⋯, in terms of the bare interaction parameter, χb, used in the FTSs, where the coefficients of the expansion are determined by a Morse calibration. However, the need to use different grid resolutions for different ordered phases generally restricts the calibration to the linear approximation, χ ≈ z∞χb, and prevents the calculation of order-order transitions. Here, we resolve these two issues by showing how the nonlinear calibration can be translated between different grids and how the UV divergence can be removed from free energy calculations. By doing so, we confirm previous observations from particle-based simulations. In particular, we show that the free energy closely matches self-consistent field theory (SCFT) predictions, even in the region where fluctuations disorder the periodic morphologies, and similarly, the periods of the ordered phases match SCFT predictions, provided the SCFT is evaluated with the nonlinear χ.

Policy Analysis of the Integration of Sports and Medicine against the Backdrop of "Healthy China": A Qualitative Study Using NVivo.

In China, the aim of integrating sports and medicine is part of a national health promotion policy. It is important to clarify the relevant policy points, policy practice distribution, and practical tools, as well as to find the weak links in the policy. In the study, there are 34 primary child nodes, 12 secondary child nodes and four parent nodes that were formed. In this study NVivo 11 software was used to analyze the content of 15 national guidelines in terms of integrating sports and medicine. From 2014 to 2021, the policy development of the integration of sports and medicine went through the beginning and growth stages. The evolutionary logic presents an inverse relationship between the policy practice's duration and the degree of state intervention. In the sequential developmental phases, policy tools were set up in an orderly transition from a single mandatory policy tool to a voluntary or hybrid policy tool, supplemented by essential policy tools. With respect to the policy content, the attention to specific service groups and sports risk assessment is insufficient. In the future, we should actively focus on the division of particular service groups and their service supply, pay closer attention to the social needs and value manifestation of sports risk assessment, and balance the proportion of policy tools in the development of the integration of sports and medicine.

Self-Induced Valley Bosonic Stimulation of Exciton Polaritons in a Monolayer Semiconductor

The newly discovered valley degree of freedom in atomically thin two-dimensional transition metal dichalcogenides offers a promising platform to explore rich nonlinear physics, such as spinor Bose-Einstein condensate and novel valleytronics applications. However, the critical nonlinear effect, such as valley polariton bosonic stimulation, has long remained an unresolved challenge due to the generation of limited polariton ground state densities necessary to induce the stimulated scattering of polaritons in specific valleys. Here, we report the self-induced valley bosonic stimulation of exciton polaritons via spin-valley locking in a WS_{2} monolayer microcavity. This is achieved by the resonant injection of valley polaritons at specific energy and wave vector, which allows spin-polarized polaritons to efficiently populate their ground state and induce a valley-dependent bosonic stimulation. As a result, we observe the nonlinear self-amplification of polariton emission from the valley-dependent ground state. Our finding paves the way for the investigation of spin ordering and phase transitions in transition metal dichalcogenides polariton Bose-Einstein condensate, offering a promising route for the realization of polariton spin lattices in moiré polariton systems and spin lasers.

Direct Magnetic Evidence, Functionalization, and Low-Temperature Magneto-Electron Transport in Liquid-Phase Exfoliated FePS3.

Magnetism and the existence of magnetic order in a material is determined by its dimensionality. In this regard, the recent emergence of magnetic layered van der Waals (vdW) materials provides a wide playground to explore the exotic magnetism arising in the two-dimensional (2D) limit. The magnetism of 2D flakes, especially antiferromagnetic ones, however, cannot be easily probed by conventional magnetometry techniques, being often replaced by indirect methods like Raman spectroscopy. Here, we make use of an alternative approach to provide direct magnetic evidence of few-layer vdW materials, including antiferromagnets. We take advantage of a surfactant-free, liquid-phase exfoliation (LPE) method to obtain thousands of few-layer FePS3 flakes that can be quenched in a solvent and measured in a conventional SQUID magnetometer. We show a direct magnetic evidence of the antiferromagnetic transition in FePS3 few-layer flakes, concomitant with a clear reduction of the Néel temperature with the flake thickness, in contrast with previous Raman reports. The quality of the LPE FePS3 flakes allows the study of electron transport down to cryogenic temperatures. The significant through-flake conductance is sensitive to the antiferromagnetic order transition. Besides, an additional rich spectra of electron transport excitations, including secondary magnetic transitions and potentially magnon-phonon hybrid states, appear at low temperatures. Finally, we show that the LPE is additionally a good starting point for the mass covalent functionalization of 2D magnetic materials with functional molecules. This technique is extensible to any vdW magnetic family.

Twin stars as probes of the nuclear equation of state: Effects of rotation through the PSR J0952-0607 pulsar and constraints via the tidal deformability from the GW170817 event

In agreement with the constantly increasing gravitational wave events, new aspects of the internal structure of compact stars can be considered. A scenario in which a first order transition takes place inside these stars is of particular interest as it can lead, under conditions, to a third gravitationally stable branch (besides white dwarfs and neutron stars), the twin stars. The new branch yields stars with the same mass as normal compact stars but quite different radii. In the present work, we focus on hybrid stars undergone a hadron to quark phase transition near their core and how this new stable configuration arises. Emphasis is to be given on the aspects of the phase transition and its parametrization in two different ways, namely with Maxwell and Gibbs construction. We systematically study the gravitational mass, the radius, and the tidal deformability, and we compare them with the predictions of the recent observation by LIGO/VIRGO collaboration, the GW170817 event, along with the mass and radius limits, suggesting possible robust constraints. Moreover, we extent the study in order to include rotation effects on the twin stars configurations. The recent discovery of the fast rotating supermassive pulsar PSR J0952-0607 triggered the effort to constrain the equation of state and moreover to examine possible predictions related to the phase transition in dense nuclear matter. We pay special attention to relate the PSR J0952-0607 pulsar properties with the twin stars predictions and mainly to explore the possibility that the existence of such a massive object would rule out the existence of twin stars. Finally, we discuss the constraints on the radius and mass of the recently observed compact object within the supernova remnant HESS J1731-347. The estimations implies that this object is either the lightest neutron star known, or a star with a more exotic equation of state.

Structure ordering and glass transition in size-asymmetric ternary mixtures of hard spheres: Variation from fragile to strong glasses.

We investigate the structure and activated dynamics of a binary mixture of colloidal particles dispersed in a solvent of much smaller-sized particles. The solvent degrees of freedom are traced out from the grand partition function of the colloid-solvent mixture which reduces the system from ternary to effective binary mixture of colloidal particles. In the effective binary mixture colloidal particles interact via effective potential that consists of bare potential plus the solvent-induced interaction. Expressions for the effective potentials and pair correlation functions are derived. We used the result of pair correlation functions to determine the number of particles in a cooperatively reorganizing cluster (CRC) in which localized particles form "long-lived" nonchemical bonds with the central particle. For an event of relaxation to take place these bonds have to reorganize irreversibly, the energy involved in the processes is the effective activation energy of relaxation. Results are reported for hard sphere colloidal particles dispersed in a solvent of hard sphere particles. Our results show that the concentration of solvent can be used as a control parameter to fine-tune the microscopic structural ordering and the size of CRC that governs the glassy dynamics. We show that a small variation in the concentration of solvent creates a bigger change in the kinetic fragility which highlights a wide variation in behavior, ranging from fragile to strong glasses. We conclude that the CRC which is determined from the static pair correlation function and the fluctuations embedded in the system is probably the sole player in the physics of glass transition.

Emergent XY* transition driven by symmetry fractionalization and anyon condensation

Anyons in a topologically ordered phase can carry fractional quantum numbers with respect to the symmetry group of the considered system, one example being the fractional charge of the quasiparticles and quasiholes in the fractional quantum Hall effect. When such symmetry-fractionalized anyons condense, the resulting phase must spontaneously break the symmetry and display a local order parameter. In this paper, we study the phase diagram and anyon condensation transitions of a \mathbb{Z}_2ℤ2 topological order perturbed by Ising interactions in the Toric Code. The interplay between the global (``onsite’’) Ising (\mathbb{Z}_2ℤ2) symmetry and the lattice space group symmetries results in a non-trivial symmetry fractionalization class for the anyons, and is shown to lead to two characteristically different confined, symmetry-broken phases. To understand the anyon condensation transitions, we use the recently introduced critical torus energy spectrum technique to identify a line of emergent 2+1D XY* transitions ending at a fine-tuned (Ising^22)* critical point. We provide numerical evidence for the occurrence of two symmetry breaking patterns predicted by the specific symmetry fractionalization class of the condensed anyons in the explored phase diagram. In combination with large-scale quantum Monte Carlo simulations we measure unusually large critical exponents \etaη for the scaling of the correlation function at the continuous anyon condensation transitions, and we further identify lines of (weakly) first order transitions in the phase diagram. As an important additional result, we discuss the phase diagram of a resulting 2+1D Ashkin-Teller model, where we demonstrate that torus spectroscopy is capable of identifying emergent XY/O(2) critical behaviour, thereby solving some longstanding open questions in the domain of the 3D Ashkin-Teller models. To establish the generality of our results, we propose a field theoretical description capturing the transition from a \mathbb{Z}_2ℤ2 topological order to either \mathbb{Z}_2ℤ2 symmetry broken phase, which is in excellent agreement with the numerical results.