We discuss the phase diagram and properties of global vortices in the non-Hermitian parity-time-symmetric relativistic model possessing two interacting scalar complex fields. The phase diagram ...contains stable PT-symmetric regions and unstable PT-broken regions, which intertwine nontrivially with the U(1)-symmetric and U(1)-broken phases, thus forming rich patterns in the space of parameters of the model. The notion of the PT symmetry breaking is generalized to the interacting theory. At finite quartic couplings, the non-Hermitian model possesses classical vortex solutions in the PT-symmetric regions characterized by broken U(1) symmetry. In the long-range limit of two-component Bose-Einstein condensates, the vortices from different condensates experience mutual dissipative dynamics unless their cores overlap precisely. For comparison, we also consider a close Hermitian analog of the system and demonstrate that the non-Hermitian two-component model possesses much richer dynamics than its Hermitian counterpart.
We demonstrate that Casimir forces associated with zero-point fluctuations of quantum vacuum may be substantially affected by the presence of dynamical topological defects. In order to illustrate ...this nonperturbative effect we study the Casimir interactions between dielectric wires in a compact formulation of Abelian gauge theory in two spatial dimensions. The model possesses topological defects, instantonlike monopoles, which are known to be responsible for nonperturbative generation of a mass gap and for a linear confinement of electrically charged probes. Despite the fact the model has no matter fields, the Casimir energy depends on the value of the gauge coupling constant. We show, both analytically and numerically, that in the strong coupling regime the Abelian monopoles make the Casimir forces short ranged. Simultaneously, their presence increases the interaction strength between the wires at short distances for a certain range of values of the gauge coupling. The wires suppress monopole density in the space between them compared to the density outside the wires. In the weak coupling regime the monopoles become dilute and the Casimir potential reduces to a known theoretical result that does not depend on the gauge coupling.
We propose a general numerical method to study the Casimir effect in lattice gauge theories. We illustrate the method by calculating the energy density of zero-point fluctuations around two parallel ...wires of finite static permittivity in Abelian gauge theory in two spatial dimensions. We discuss various subtle issues related to the lattice formulation of the problem and show how they can successfully be resolved. Finally, we calculate the Casimir potential between the wires of a fixed permittivity, extrapolate our results to the limit of ideally conducting wires and demonstrate excellent agreement with a known theoretical result.
We study properties of SU(2) Yang-Mills theory on a four-dimensional Euclidean spacetime in which two directions are compactified into a finite two-dimensional torus T2 while two others constitute a ...large R2 subspace. This Euclidean T2×R2 manifold corresponds simultaneously to two systems in a (3+1) dimensional Minkowski spacetime: a zero-temperature theory with two compactified spatial dimensions and a finite-temperature theory with one compactified spatial dimension. Using numerical lattice simulations we show that the model exhibits two phase transitions related to the breaking of center symmetries along the compactified directions. We find that at zero temperature the transition lines cross each other and form the Greek letter γ in the phase space parametrized by the lengths of two compactified spatial dimensions. There are four different phases. We also demonstrate that the compactification of only one spatial dimension enhances the confinement property and, consequently, increases the critical deconfinement temperature.
Aims
This study aimed to evaluate lysis of Escherichia coli stationary cell cultures induced by the combined action of bacteriophage T5 endolysin (l‐alanyl‐d‐glutamate peptidase) and low doses of ...various cationic agents permeabilizing the outer membrane of Gram‐negative bacteria (polymyxin B, gramicidin D, poly‐l‐lysine, chlorhexidine and miramistin).
Methods and Results
The enzyme activity was assayed with the turbidimetric method. Antimicrobial activity was assessed through the number of colony‐forming units (CFUs); the results of calculation were represented as logarithmic units. The optical microscopy examination of bacterial cells was conducted in the phase‐contrast mode. The use of bacteriophage T5 endolysin in combination with polymyxin B (0·4 μg ml−1) or chlorhexidine (0·5 μg ml−1) made it possible to reduce the number of CFUs by five orders of magnitude; and in combination with poly‐l‐lysine (80 μg ml−1) by four orders, as compared to control. The endolysin was found to be a thermostable protein: it retained ~65% of its initial activity after heating for 30 min at 90°C. Examining the curves of its thermal denaturation revealed the half‐transition temperature to be 56·3 ± 1·0°C. Circular dichroism spectra showed that after recooling the protein restored up to 80% of its native structure.
Conclusions
A substantial synergistic effect of the bacteriophage T5 endolysin and membrane‐permeabilizing compounds was demonstrated.
Significance and Impact of the Study
The study of thermal stability of the bacteriophage T5 endolysin and the quantified assessment of its antimicrobial activity have been done for the first time. The approach examined lays foundations for designing a two‐component preparation which would effectively lyse cells of Gram‐negative pathogens from outside.
We propose and test a new approach to computation of canonical partition functions in lattice QCD at finite density. We suggest a few steps procedure. We first compute numerically the quark number ...density for imaginary chemical potential iμqI. Then we restore the grand canonical partition function for imaginary chemical potential using the fitting procedure for the quark number density. Finally we compute the canonical partition functions using high precision numerical Fourier transformation. Additionally we compute the canonical partition functions using the known method of the hopping parameter expansion and compare results obtained by two methods in the deconfining as well as in the confining phases. The agreement between two methods indicates the validity of the new method. Our numerical results are obtained in two flavor lattice QCD with clover improved Wilson fermions.
Using numerical simulations of lattice QCD with physical quark masses, we reveal the influence of magnetic-field background on chiral and deconfinement crossovers in finite-temperature QCD at low ...baryonic density. In the absence of thermodynamic singularity, we identify these transitions with inflection points of the approximate order parameters: normalized light-quark condensate and renormalized Polyakov loop, respectively. We show that the quadratic curvature of the chiral transition temperature in the "temperature–chemical potential" plane depends rather weakly on the strength of the background magnetic field. At weak magnetic fields, the thermal width of the chiral crossover gets narrower as the density of the baryon matter increases, possibly indicating a proximity to a real thermodynamic phase transition. Remarkably, the curvature of the chiral thermal width flips its sign at eBfl≃0.6 GeV2, so that above the flipping point B>Bfl, the chiral width gets wider as the baryon density increases. Approximately at the same strength of magnetic field, the chiral and deconfining crossovers merge together at T≈140 MeV. The phase diagram in the parameter space "temperature-chemical potential-magnetic field" is outlined, and single-quark entropy and single-quark magnetization are explored. The curvature of the chiral thermal width allows us to estimate an approximate position of the chiral critical end point at zero magnetic field: (TcCEP,μBCEP)=(100(25) MeV,800(140) MeV). These results are based on numerical simulations performed mainly at the lattice time extension Nt=6.
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