The gluon and ghost propagator and the influence of Gribov copies

The dependence of the Landau gauge gluon and ghost propagators on the choice of Gribov copies is studied in pure SU(3) lattice gauge theory. Whereas the influence on the gluon propagator is small, the ghost propagator becomes clearly affected by the copies in the infrared region. We compare our data with the infrared exponents predicted by the Dyson-Schwinger equation approachComment: Talk presented at Lattice2004(topology), Fermilab, June 21-26, 2004, 3 pages, 3 figure

Melt crystallization of ferroelectric copolymers of poly(vinylidene fluoride-trifluoroethylene)/

This dissertation is a study of the phase transition and melt crystallization of ferroelectric copolymers of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) containing 83 mol% poly(vinylidene fluoride). The microstructure of crystallized P(VDF-TrFE) are characterized by vibrational spectroscopy to determine their chain conformation distribution, wide-angle X-ray diffraction (WAXD) to measure the crystal structure and determine the content of $\alpha$ and $\beta$ crystal phases. Differential scanning calorimetry (DSC) is used to measure the transition temperatures and their enthalpies. P(VDF-TrFE) is a polymorphic system exhibiting a Curie transition below its melting temperature, at which the copolymer undergoes a long range conformational change from a predominantly trans structure ($\beta$ phase) which can be ferroelectric, to a structure which has a mixture of trans and gauche conformations and is called the paraelectric $\alpha$ phase. Variable temperature FTIR studies have been made to follow the phase transition and to understand the multiple phase behavior that has been suggested for these copolymers. Factor analysis has been applied to the FTIR data to determine the number of crystal phases present for this copolymer composition. Melt crystallization under nonisothermal and isothermal conditions has been used to modify the structure of the copolymers and change both the Curie and melting temperatures. It is found that with slow cooling rates from the melt through the crystallization temperature, there is a stabilization of the paraelectric $\alpha$ phase which is then retained to different degrees on passing through the Curie transition on cooling. Under all crystallization conditions the copolymers exhibit two Curie transitions on cooling whose temperatures and intensities vary with cooling rate and crystallization time. The Curie temperature on cooling and subsequent heating is decreased upon slower cooling, reflecting an increase in the gauche chain conformers as evidenced by FT-Raman spectroscopy. WAXD data show that there are $\alpha$ and $\beta$ phase crystals present in samples that have been cooled slowly, accompanied by an increase in interplanar spacing which indicates that the $\beta$ phase also contains gauche defects. Longer isothermal crystallization at 135\sp\circC shows also that there is an increase in $\alpha$ phase content with longer crystallization time, though when crystallization is carried out at 135\sp\circC there is always a coexistence of $\alpha$ and $\beta$ phases in the final room temperature structure. Highly oriented P(VDF-TrFE) copolymers were prepared by solid-state coextrusion to aid in understanding the vibrational assignments in the copolymer. Infrared dichroism and WAXD were used to assess the sample orientation and measure the transition moment angles for some of the vibrations in the spectrum

Landau gauge ghost and gluon propagators and the Faddeev-Popov operator spectrum

In this talk we report on a recent lattice investigation of the Landau gauge gluon and ghost propagators in pure SU(3) lattice gauge theory with a special emphasis on the Gribov copy problem. In the (infrared) region of momenta $q^2 \le 0.3 \mathrm{GeV}^2$ we find the corresponding MOM scheme running coupling $\alpha_s(q^2)$ to rise in $q$. We also report on a first SU(3) computation of the ghost-gluon vertex function showing that it deviates only weakly from being constant. In addition we study the spectrum of low-lying eigenvalues and eigenfunctions of the Faddeev-Popov operator as well as the spectral representation of the ghost propagator.Comment: talk given by M. M.-P. at the Workshop on Computational Hadron Physics, Cyprus, September 200

Robot-assisted radical cystectomy with intracorporeal heterotopic neocystis: a single-centre experience of complications

Introduction. Bladder cancer (BCa) ranks 10th among all diagnosed malignant tumours. To date, radical cystectomy (RCE) with pelvic lymphadenectomy is the gold standard for the treatment of aggressive forms of BCa. The development of minimally invasive technologies has contributed to the active introduction of robot-assisted interventions into surgical practise. RCE is a modern and relevant method for treating muscle-invasive BCa and high-risk non-muscle-invasive BCa. Over the past decade, many works have been accumulated that demonstrate the success of robot-assisted RCE with intracorporeal neocystis.Objective. To analyse the complications classified according to Clavien-Dindo after robot-assisted radical cystectomies with intracorporeal heterotopic neocystis based on a single centre.Materials & methods. From 2021 to 2022, a retrospective study was conducted based on Bashkir State Medical University Clinics aimed at studying complications after robot-assisted RCEs. The group investigated consisted of 200 male and female patients with an established diagnosis of BCa. All patients were shown surgical treatment in volume of RCE by Bricker with pelvic lymphadenectomy. Surgical intervention was performed using the DaVinci ® Si robot-assisted system. After 30 and 90 days, the complications that occurred and the ways to correct them were evaluated.Results. Only 35 patients (17.5%) had 30-day complications, which were grade I-III. Fourteen (7%) patients had 90-day complications having II and III degrees. Patients with grade III or II and III complications occurred during the first 30 days after surgical treatment subsequently had 90-day complications (p < 0.05). There were no statistically significant differences between the types of 30-day complications of II and III degree and the subsequent 90-day complications (p < 0.05).Conclusion. Robot-assisted RCE is an effective and technologically advanced method of treating patients with aggressive forms of BCa. Our study demonstrates low rates of surgical complications after this surgical intervention

Blow-up regimes in failure of rock specimens

For damage evaluation, the stage of superfast catastrophic failure of a medium and its mechanical behavior in a state of self-organized criticality prior to the onset of a blow-up fracture mode is of great interest for identification of its precursors. In this work, the data of experimental and numerical investigations of mechanical behavior of a medium before its catastrophic failure and the onset of a blow-up fracture mode are presented. Rock samples and ceramic specimens are subjected to three-point bending and uniaxial compression testing. Surface velocities of the loaded specimens are registered using a laser Doppler vibrometer. The blow-up regime duration is measured to be about 10–20 ms. The specimens’ mechanical behavior is numerically simulated under experimental conditions, including the regime of catastrophic fracture. The model parameters of damage accumulation are determined from a comparison with the experimental data. A number of features of the material mechanical response before the catastrophic fracture are identified, which could be treated as failure precursors

Coulomb Energy, Remnant Symmetry, and the Phases of Non-Abelian Gauge Theories

We show that the confining property of the one-gluon propagator, in Coulomb gauge, is linked to the unbroken realization of a remnant gauge symmetry which exists in this gauge. An order parameter for the remnant gauge symmetry is introduced, and its behavior is investigated in a variety of models via numerical simulations. We find that the color-Coulomb potential, associated with the gluon propagator, grows linearly with distance both in the confined and - surprisingly - in the high-temperature deconfined phase of pure Yang-Mills theory. We also find a remnant symmetry-breaking transition in SU(2) gauge-Higgs theory which completely isolates the Higgs from the (pseudo)confinement region of the phase diagram. This transition exists despite the absence, pointed out long ago by Fradkin and Shenker, of a genuine thermodynamic phase transition separating the two regions.Comment: 18 pages, 19 figures, revtex

Оценка уровня цифровой активности организаций розничной торговли России

The paper presents the main results of conjuncture monitoring which characterize the digital activity of retail trade organizations in 2018. The objects of observation are large, medium and small retail companies registered in Russia. The main goal of this work is to evaluate digital activity level of retail sector using the developed non-quantitative indicators that meet international standards and the country’s digital agenda. The presented set of harmonized indicators made it possible to identify the trends, scope and intensity of the spread of digital technologies in organizations. The level and intensity of digitalization are first determined on the basis of entrepreneurial opinions and intentions regarding the pace and scale of introducing digital technologies, readiness for digital transition, necessary skills to work with digital technologies, the use of specific digital products, as well as the main factors hindering digital transformation.В работе представлены основные результаты конъюнктурного обследования, характеризующие цифровую активность организаций розничной торговли в 2018 г. Объектами наблюдения были крупные, средние и малые предприятия розничной торговли, зарегистрированные в России. Основная цель данной работы заключалась в оценке уровня цифровой активности розничной торговли с помощью разработанных неколичественных индикаторов, соответствующих международным стандартам и цифровой повестке страны. Представленный набор гармонизированных показателей позволил выявить тенденции, масштаб и интенсивность распространения цифровых технологий в организациях. Уровень и интенсивность цифровизации впервые были определены на основе предпринимательских мнений и намерений относительно темпов и масштабов освоения цифровых технологий, готовности к цифровому переходу, сложившихся цифровых навыков, применения конкретных цифровых продуктов, а также основных факторов, препятствующих цифровой трансформации

Propagators in Coulomb gauge from SU(2) lattice gauge theory

A thorough study of 4-dimensional SU(2) Yang-Mills theory in Coulomb gauge is performed using large scale lattice simulations. The (equal-time) transverse gluon propagator, the ghost form factor d(p) and the Coulomb potential V_{coul} (p) ~ d^2(p) f(p)/p^2 are calculated. For large momenta p, the gluon propagator decreases like 1/p^{1+\eta} with \eta =0.5(1). At low momentum, the propagator is weakly momentum dependent. The small momentum behavior of the Coulomb potential is consistent with linear confinement. We find that the inequality \sigma_{coul} \ge \sigma comes close to be saturated. Finally, we provide evidence that the ghost form factor d(p) and f(p) acquire IR singularities, i.e., d(p) \propto 1/\sqrt{p} and f(p) \propto 1/p, respectively. It turns out that the combination g_0^2 d_0(p) of the bare gauge coupling g_0 and the bare ghost form factor d_0(p) is finite and therefore renormalization group invariant.Comment: 10 pages, 7 figure

Numerical Study of the Ghost-Gluon Vertex in Landau gauge

We present a numerical study of the ghost-gluon vertex and of the corresponding renormalization function \widetilde{Z}_1(p^2) in minimal Landau gauge for SU(2) lattice gauge theory. Data were obtained for three different lattice volumes (V = 4^4, 8^4, 16^4) and for three lattice couplings \beta = 2.2, 2.3, 2.4. Gribov-copy effects have been analyzed using the so-called smeared gauge fixing. We also consider two different sets of momenta (orbits) in order to check for possible effects due to the breaking of rotational symmetry. The vertex has been evaluated at the asymmetric point (0;p,-p) in momentum-subtraction scheme. We find that \widetilde{Z}_1(p^2) is approximately constant and equal to 1, at least for momenta p > ~ 1 GeV. This constitutes a nonperturbative verification of the so-called nonrenormalization of the Landau ghost-gluon vertex. Finally, we use our data to evaluate the running coupling constant \alpha_s(p^2).Comment: 19 pages, 6 figures, 9 tables, using axodraw.sty; minor modifications in the abstract, introduction and conclusion

Lattice gluodynamics computation of Landau-gauge Green's functions in the deep infrared

We present recent results for the Landau-gauge gluon and ghost propagators in SU(3) lattice gluodynamics obtained on a sequence of lattices with linear extension ranging from L=64 to L=96 at $\beta = 5.70$, thus reaching "deep infrared" momenta down to 75 MeV. Our gauge-fixing procedure essentially uses a simulated annealing technique which allows us to reach gauge-functional values closer to the global maxima than standard approaches do. Our results are consistent with the so-called decoupling solutions found for Dyson-Schwinger and functional renormalization group equations.Comment: 6 pages, 5 figures. References added, minor changes to match published versio