Order Transition Research Articles

Knowing When to Step Down as a Leader

This article explores when it is appropriate for leaders to consider stepping down from their roles and passing the torch to new leadership. It examines signs that it may be time to transition based on research on leadership fatigue, stagnating vision, and succession planning. Specific factors discussed include declining health and enthusiasm from prolonged stress, an inability to drive innovative strategies, and having a capable successor prepared to take over. The article then outlines practical signs for leaders in industries like financial services, healthcare, technology, and non-profits that a transition should be considered. It provides examples of Microsoft CEO Satya Nadella and OWN founder Oprah Winfrey effectively navigating leadership successions. Finally, the article emphasizes the importance of succession planning, identifying the right time for an orderly transition, and ensuring the smooth handoff of leadership responsibilities to allow organizations to continue thriving under new vision and perspectives.

Dominant role of charge ordering on high harmonic generation in Pr0.6Ca0.4MnO3

High harmonic generation (HHG) is a typical high-order nonlinear optical phenomenon and can be used to probe electronic structures of solids. Here, we investigate the temperature dependence of HHG from Pr0.6Ca0.4MnO3 in the range of 7–294 K, including the charge ordering (CO) transition and magnetic transition temperatures. The high harmonic (HH) intensity remains almost constant in the high-temperature charge-disordered phase. However, as the temperature is lowered, it starts to increase near the CO transition temperature where an optical gap related to the CO appears. The anomalous gap energy dependence resembles the one recently reported in a Mott insulator. We attribute the suppression of the HH intensity at high temperatures to the destructive interference among HH emissions from thermally activated multiple charge configurations. Our results suggest that HHG is a promising tool for probing the fluctuation of local order in strongly correlated systems. Published by the American Physical Society 2024

Test of universality at first order phase transitions: The Lebwohl-Lasher model.

Finite size scaling for a first order phase transition, where a continuous symmetry is broken, is tested using an approximation of Gaussian probability distributions with a phenomenological "degeneracy" factor. Predictions are compared to the data from Monte Carlo simulations of the Lebwohl-Lasher model on L × L × L simple cubic lattices. The data show that the intersection of the fourth-order cumulant of the order parameter for different lattice sizes can be expressed in terms of the relative degeneracy q = 4π of the ordered and disordered phases. This result further supports the concept of universality at first order transitions developed recently.

Disclosing the magnetic ground state of PrBaMn2O6

In this work, we report a neutron diffraction study on a single crystal of the layered PrBaMn2O6 perovskite. This compound undergoes two consecutive magnetic transitions with decreasing temperature. At TC ≈ 309 K, a long-range ferromagnetic ordering is established with the Mn magnetic moments oriented along the c axis. Below TN ≈ 240 K, a spin reorientation gives rise to a sudden decrease of the magnetization and the formation of an antiferromagnetic order. This magnetic transition is also accompanied by an electronic localization caused by a structural phase transition from a high-temperature tetragonal phase (P4/mmm) into a low-temperature orthorhombic one (P21am). Our neutron diffraction study at 12 K has unambiguously identified that the ground magnetic structure for this compound is a layered antiferromagnetic structure along the c axis with the Mn moments oriented in the ab plane along one diagonal of the primitive tetragonal cell. No sign of magnetic scattering associated to a CE-type magnetic structure was found in our study, discarding its occurrence in this compound. This result excludes the occurrence of a charge order transition to account for the electronic localization and it is fully consistent with previous structural studies showing a unique crystallographic site for Mn atom in the low-temperature phase. A symmetry analysis was carried out to identify the magnetic space group of the ferromagnetic order above TN and the two possible groups for the antiferromagnetic ordering below TN.

Effects of quantum dots on the nematic to smectic-A phase transition

ABSTRACT Experiments on the composites of liquid crystals and quantum dots showed the significant role of quantum dots on the properties of the nematic–smectic-A phase transition. The effects of quantum dots on the nematic-smectic-A phase transition have been discussed using Flory- Huggins theory of isotropic mixing and Landau-de Gennes theory. The impact of quantum dots on the smectic-A order parameters, nematic–smectic-A transition temperature, splay and bend elastic constants has been discussed. The smectic-A order parameters, transition temperature and elastic constants decrease with the increase of volume fraction of quantum dots.

Microbiological Analysis of Wild Meat Seized in the Province of Orellana and Its Impact on the SDGS

Objective: The objective of this study is to microbiologically analyse wild meat seized by the Ministry of Environment, Water and Ecological Transition in order to contribute to food security in the province of Orellana. The specific objectives are: 1. To obtain samples of seized wild meat using microbiological monitoring techniques. 2. 2. To analyse the samples microbiologically using techniques standardised by the AOAC. 3. To quantify the microorganisms present in order to evaluate the shelf life and safety of the product according to NTE INEN 1338 and NTE INEN 183 standards. Method: The methodology included the collection of samples of wild meat seized in the province of Orellana, microbiological analysis in the laboratory using techniques standardised by AOAC, and evaluation of the results according to Ecuadorian standards NTE INEN 1338 and NTE INEN 183. Statistical analyses including ANOVA were carried out to compare contamination levels between species. Results and Discussion: Samples of 8 wild species were analysed. The results revealed high levels of microbiological contamination in most of the samples, exceeding the limits established by the regulations for Mesophilic Aerobes, Escherichia coli, Staphylococcus aureus and Salmonella. 87.5% of the samples did not meet the limits for mesophilic Aerobes, 100% exceeded the limits for E. coli and S. aureus, and 75% had Salmonella. Research Implications: The results have significant implications for food safety and public health in the region. They suggest the need to implement stricter control measures and surveillance of illegal bushmeat trafficking, as well as the importance of educating the population about the risks associated with bushmeat consumption. Originality/Value: This study provides updated and specific data on the microbiological quality of wild meat seized in the province of Orellana, contributing to the literature on food security and wildlife conservation in the Amazon region of Ecuador.

Partition function zeros of zeta-urns

We discuss the distribution of partition function zeros for the grand-canonical ensemble of the zeta-urn model, where tuning a single parameter can give a first or any higher order condensation transition. We compute the locus of zeros for finite-size systems and test scaling relations describing the accumulation of zeros near the critical point against theoretical predictions for both the first and higher order transition regimes.

Disentangling transitions in topological order induced by boundary decoherence

Disentangling transitions in topological order induced by boundary decoherence

Unconventional insulator-to-metal phase transition in Mn3Si2Te6

The nodal-line semiconductor Mn3Si2Te6 is generating enormous excitment due to the recent discovery of a field-driven insulator-to-metal transition and associated colossal magnetoresistance as well as evidence for a new type of quantum state involving chiral orbital currents. Strikingly, these qualities persist even in the absence of traditional Jahn-Teller distortions and double-exchange mechanisms, raising questions about exactly how and why magnetoresistance occurs along with conjecture as to the likely signatures of loop currents. Here, we measured the infrared response of Mn3Si2Te6 across the magnetic ordering and field-induced insulator-to-metal transitions in order to explore colossal magnetoresistance in the absence of Jahn-Teller and double-exchange interactions. Rather than a traditional metal with screened phonons, the field-driven insulator-to-metal transition leads to a weakly metallic state with localized carriers. Our spectral data are fit by a percolation model, providing evidence for electronic inhomogeneity and phase separation. Modeling also reveals a frequency-dependent threshold field for carriers contributing to colossal magnetoresistance which we discuss in terms of polaron formation, chiral orbital currents, and short-range spin fluctuations. These findings enhance the understanding of insulator-to-metal transitions in new settings and open the door to the design of unconventional colossal magnetoresistant materials.

Lombalgia crônica e sua condução clínica

Chronic low back pain is a multifactorial condition that affects the spine and has a complex pathophysiological basis. This article aims to analyze the clinical consequences and factors that influence the phenotypic diversity of this condition. Phenotypic variation is crucial to allow adaptation throughout evolution, but this variation must be controlled to avoid compromising the vital functions of the musculoskeletal system. Vertebral structures maintain their characteristics and signaling pathways over time, with conserved epigenetic modifications. Phenotypic diversity in the vertebral unit occurs due to processes of ontogeny, remodeling, phenotypic variation, adaptation, and environmental sensitivity. These processes involve internal and external stressors, orderly transitions of cell development, temporal changes in development, rapid adaptation, and epigenetic modifications.

Osteoartrite: Consequência evolutiva?

Osteoarthritis is a degenerative disease that affects the joints and is a multifactorial disease. This article aims to analyze its evolutionary consequences and the factors that influence the phenotypic diversity of the disease. Phenotypic variation among living things is crucial to enable natural selection, but this variation needs to be limited to avoid the collapse of the vital functions of the organic system. Skeletal tissue cell types have their origins in aquatic animals and have maintained their characteristics and signaling pathways during the transition to terrestrial life, with conserved epigenetic modifications. Phenotypic diversity in the osteochondral unit occurs due to processes of ontogeny, remodeling, phenotypic variation, adaptation, and environmental sensitivity. These processes involve internal and external stressors, orderly transitions of cell development, changes in the timing of development, rapid adaptation, and epigenetic modifications.

The electrophysiology of sequential adjustments of dual-task order coordination.

Performing two tasks simultaneously involves the coordination of their processing. This task coordination is particularly required in dual-task situations with varying task orders. When task order switches between subsequent trials, task order coordination leads to task order switch costs in comparison with order repetitions. However, it is open, whether task order coordination is exclusively controlled by the relation of the task orders of the current and the previous trials, or whether additional conditions such as task order before the previous trial leads to a behavioral and neural adjustment of task order coordination. To answer this question, we reanalyzed the data of two previously published experiments with order-cued dual-task paradigms. We did so with regard to whether task order switch costs and the EEG component order-switch positivity in the current dual-task trial would be modulated by order switches vs. repetitions in the previous trial (Trial N-1). In Experiment 1, we found a modulation of the task order switch costs in RTs and response reversals; these costs were reduced after an order switch compared with order repetitions in Trial N-1. In Experiment 2, there were no effects on the task order switch costs in the behavioral data. Nonetheless, we found the order-switch positivity to be strongly modulated by the order transition of the previous trial in both experiments. The order-switch positivity was substantially reduced if the previous trial was an order switch (compared to an order repetition) by itself. This implies that order coordination of dual tasks is adjusted in a gradual way depending on trial's history.

A new method for joining Incoloy825/X65 composite plate by laser and CMT welding

Incoloy825/X65 composite plate had good application in the submarine transporting pipelines due to combination of the high resistance to Cl− corrosion and preferred mechanical properties. But the enrollment of Fe into Ni layer deteriorated the corrosion resistance in welding the transition layer of composite plate. In view of this, the paper respectively adopted the laser welding on the Ni layer without filler metal and then the swing arc CMT welding with steel filler metal as a transition in order to inhibit the Fe into Ni layer. The results showed the laser welding bead on Ni layer with uniform and fine γ microstructure ensured the better corrosion resistance. The CMT welding controlled the dilution rate under 6 % through optimizing the welding speed and swing frequency of arc. Finally, the tensile strength of transition weld was up to 500 MPa surpassing the base metal of 490 MPa. The clad bead with charge transfer resistance of 756 kΩ·cm2 satisfied general submarine pipeline anti-corrosion requirement.

Hydroflux Synthesis and Structural Phase Transition of Rare-Earth Borate Hydroxides Na2[RE(BO3)(OH)2] (RE = Y, Gd-Er).

Reacting RE2O3 and H3BO3 in an ultra-alkaline NaOH hydroflux at about 250 °C yielded pure, crystalline samples of Na2[RE(BO3)(OH)2] (RE = Y, Gd-Er). The compounds dehydrate to Na3RE(BO3)2 upon heating in air to about 500 °C. Na2[RE(BO3)(OH)2] (RE = Tb-Er) are photoluminescent under UV radiation. Their UV-Vis spectra show the typical absorptions associated with 4f-4f transitions and absorption edges in the UV (band gaps ≥ 5.7 eV). The RE3+ cation is coordinated by seven oxygen atoms, which define a distorted pentagonal bipyramid. The bipyramids share trans-edges of their base forming infinite chains. Triangular (BO3)3- groups connect the chains into layers. The crystal structure of Na2[Ho(BO3)(OH)2] was investigated at various temperatures in the range 100 K ≤ T ≤ 320 K. Above 310(2) K, the compound crystallizes in the orthorhombic space group Cmcm (β-phase), below, it undergoes a displacive phase transition of second order resulting in a monoclinic structure in space group C2/c (α-phase). The critical exponents derived from different structural parameters indicate a cooperative distortion of the borate layers, but a rather uncorrelated adaptation of the sodium cations to their local environment. The other compounds of the series also adopt the structure of the α-phase at 296 K.

Study of mesomorphic, thermal and optical properties of 4-pentylbenzoic acid (5BA) and 4-n-alkyl-4́-cyanobiphenyl (nCB; n = 5, 6) supramolecular hydrogen bonded mesogenic complexes

Within the scope of this study, the process of producing and analyzing a liquid crystalline substance (supramolecular hydrogen-bonded mesogen) is presented. The formation of this mesogen involves the use of two chemicals, namely 4-pentylbenzoic acid (5BA) and 4-n-alkyl-4́-cyanobiphenyl (nCB; n = 5, 6). Equimolar (1:1) 5BA/5CB and 5BA/6CB binary combination samples have been organized by using one at a time mixing 5CB and 6CB liquid crystal chemical substances with 5BA. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) are employed for the examination of phase transitions, and liquid crystalline phase texture properties of the produced mesogens. The phase transformation sequence that occurred during heating and cooling is Crystal (Cr) ↔ Smectic A (SmA) ↔ Nematic (N) ↔ Isotropic (I) with the 1st order or weakly 1st order transition. The nematic range value observed for 5BA/6CB is considerably smaller than the nematic range value observed for 5BA/5CB, but the thermal mesophase range value for both is approximately the same. Fourier-transform infrared (FTIR) evaluation of 5BA, 5CB, and their hydrogen-bonded combos (5BA/nCB; n = 5, 6) confirmed attribute peaks. The X-ray diffraction (XRD) study revealed that the produced mesogens possess a crystalline structure. In addition, UV–Vis experiments demonstrated that the increase in alkyl chain length in the combination resulted in a decrease in absorbance and wavelength values, while leading to an increase in absorbency and band gap energy values. These results propose workable purposes for the synthesized substances in liquid crystal displays and other optoelectronic devices. Overall, the findings display the feasibility and viability of these novel hydrogen-bonded liquid crystalline mesogens in various technological applications.

First order phase transition with the functional renormalization group method

The renormalization group method, more specifically the Wegner-Houghton equation, is used to find first order phase transitions in a simple scalar field theory with a polynomial potential. An improved definition of the running parameters allows us to explore the renormalization group flow down to the IR endpoint and to locate phase transitions. Beyond the expected first order transition further radiative correction generated first and second order transitions are found. The phase diagram is reviewed by a Monte-Carlo simulation of the lattice regulated version of the theory but the serious slow down of the convergence prevents us from obtaining conclusive results from the simulation. Published by the American Physical Society 2024

Fluctuation-induced first order transition to collective motion

The nature of the transition to collective motion in assemblies of aligning self-propelled particles remains a long-standing matter of debate. In this article, we focus on dry active matter and show that weak fluctuations suffice to generically turn second-order mean-field transitions into a ‘discontinuous’ coexistence scenario. Our theory shows how fluctuations induce a density-dependence of the polar-field mass, even when this effect is absent at mean-field level. In turn, this dependency on density triggers a feedback loop between ordering and advection that ultimately leads to an inhomogeneous transition to collective motion and the emergence of inhomogeneous travelling bands. Importantly, we show that such a fluctuation-induced first order transition is present in both metric models, in which particles align with neighbors within a finite distance, and in ‘topological’ ones, in which alignment is based on more complex constructions of neighbor sets. We compute analytically the noise-induced renormalization of the polar-field mass using stochastic calculus, which we further back up by a one-loop field-theoretical analysis. Finally, we confirm our analytical predictions by numerical simulations of fluctuating hydrodynamics as well as of topological particle models with either k-nearest neighbors or Voronoi alignment.

Nonequilibrium tricritical behavior in anisotropic XY ferromagnet driven by elliptically polarized propagating magnetic field wave

The three-dimensional anisotropic XY ferromagnet, driven by an elliptically polarized propagating magnetic field wave, has been extensively investigated by Monte Carlo simulation with the Metropolis single spin flip algorithm. Both the effects of the bilinear exchange type and the single-site anisotropies are thoroughly investigated. The time-averaged magnetization (over the complete cycle of the elliptically polarized propagating magnetic field wave) components play the role of the dynamic order parameter. For a fixed set of values of the strength of anisotropy and the field amplitudes, the system has been found to get dynamically ordered at a pseudocritical temperature. The pseudocritical temperature of such a dynamic nonequilibrium phase transition has been found to depend both on the strength of anisotropy and the amplitudes of the elliptically polarized propagating magnetic field wave. A comprehensive phase diagram is represented here in the form of an image plot of the pseudocritical temperature in the plane formed by the strength of anisotropy and field amplitudes. Interestingly, this nonequilibrium phase transition has been found to be discontinuous (first order) for higher values of the field amplitude. On the other hand, the continuous (second order) transition has been noticed for lower values of the field amplitude. Such an interesting nonequilibrium tricritical behavior has been observed in driven XY ferromagnet. The order of such a nonequilibrium phase transition has been confirmed by the thermal variation (near the transition) of the statistical distribution of the order parameter and by the thermal variation of the fourth-order Binder cumulant. In the plane formed by field amplitude and anisotropy, a tricritical line has been shown as the accompanying (and complementary) phase diagram. The dependence of the pseudocritical temperature, on the frequency and wavelength of the elliptically polarized propagating magnetic field wave, has also been reported.

Baryogenesis via QCD preheating with nonadiabatic baryon chemical potential

The chiral phase transition in QCD can be supercooled in the thermal history of the universe to be instantaneously out-of equilibrium, if QCD is coupled to a dark QCD sector exhibiting the dark chiral phase transition of the first order. In that case the QCD sigma meson field (as the chiral order parameter, or the light quark condensate) starts to roll in a nonadiabatic way down to the true QCD vacuum. Meanwhile a dynamic baryonic chemical potential can be generated solely within QCD, which is governed by the dynamic motion of the QCD sigma meson field, analogously to the spontaneous baryogenesis or the leptogenesis via the Higgs or axionlike relaxation scenario. When QCD is further allowed to communicate with a dark fermion with mass of order of 1 GeV and the baryon number violating coupling to neutron, the nonadiabatic QCD sigma motion along with the nonadiabatic baryon chemical potential can trigger the preheating and produce the baryon number asymmetry. We discuss this scenario in details to find that the QCD-induced dynamic baryon chemical potential plays a significant role for the QCD preheating and the baryogenesis, which yields the desired amount of the asymmetry today consistently with current astrophysical, cosmological, and terrestrial experimental constraints. Cosmological and phenomenological consequences characteristic to the present scenario are also addressed.

Large deviations in statistics of the local time and occupation time for a run and tumble particle.

We investigate the statistics of the local time T=∫_{0}^{T}δ(x(t))dt that a run and tumble particle (RTP) x(t) in one dimension spends at the origin, with or without an external drift. By relating the local time to the number of times the RTP crosses the origin, we find that the local time distribution P(T) satisfies the large deviation principle P(T)∼e^{-TI(T/T)} in the large observation time limit T→∞. Remarkably, we find that in the presence of drift the rate function I(ρ) is nonanalytic: we interpret its singularity as a dynamical phase transition of first order. We then extend these results by studying the statistics of the amount of time R that the RTP spends inside a finite interval (i.e., the occupation time), with qualitatively similar results. In particular, this yields the long-time decay rate of the probability P(R=T) that the particle does not exit the interval up to time T. We find that the conditional end-point distribution exhibits an interesting change of behavior from unimodal to bimodal as a function of the size of the interval. To study the occupation time statistics, we extend the Donsker-Varadhan large-deviation formalism to the case of RTPs, for general dynamical observables and possibly in the presence of an external potential.