The weak-gravity bound and the need for spin in asymptotically safe matter-gravity models

We discover a weak-gravity bound in scalar-gravity systems in the asymptotic-safety paradigm. The weak-gravity bound arises in these systems under the approximations we make, when gravitational fluctuations exceed a critical strength. Beyond this critical strength, gravitational fluctuations can generate complex fixed-point values in higher-order scalar interactions. Asymptotic safety can thus only be realized at sufficiently weak gravitational interactions. We find that within truncations of the matter-gravity dynamics, the fixed point lies beyond the critical strength, unless spinning matter, i.e., fermions and vectors, is also included in the model.

Principles of certification of metals for susceptibility to brittleness by the criterion of critical strength

Problem definition. Existing evaluation system of liability to brittle fracture is based on specifying the critical temperature Tc of ductile/brittle transition for specimens with stress concentrator (SC) and uses relative values of impact toughness (KCV, KCU) and widening (ψк). Thus the Tc becomes relative and it is not possible to measure brittleness or embrittlement degree for specimens with SC. Paper purpose. Neutralize the system faults of evaluation system of liability to brittle fracture of constructional alloys with SC. The concept is to change the KCV (KCU) or ψк parameters by critical strength parameter (ϭ0,2с at Tc). Conclusions. Fracture of the specimen with SC (ϭNF) on YTS (ϭ0,2с) at Tc (or room TR) as embrittlement criterion is proposed instead of relative values of (KCV, KCU) and (ψк). The ϭNF / ϭ0,2 = BrNF ratio is a degree of reliability for specimen with SC (BrNF > 1) or embrittlement measure (BrNF < 1). The BrNF value is a quantitative measure of the fracture resistivity of the specimen with SC or crack. Correlation ratio between Br and BrNF for each type of SC has been found. It allows to use the calculation of embrittlement liability based on metal strength for test of metals without full scale tests of metal specimens with SC. Keywords: embrittlement; fracture degree; fracture resistivity; critical temperature; critical strength; strengthreliability of the specimen with SC

The anomalous electronic structure of electron-doped cuprate superconductors by considering the next higher harmonics of the superconducting gap

Based on the self-consistent mean field theory by considering the next higher harmonics of the superconducting (SC) gap, we discuss the energy and momentum dependence of the electron spectrum in electron-doped cuprate superconductors. By calculation of the electron spectral function, it is shown that the weight of the electron spectrum at the Fermi energy is strongly redistributed by the next higher harmonics of the SC gap in electron-doped cuprate superconductors, especially for the antinodal region. At the antinodal region, the weight of the electron spectrum at the Fermi surface increases with the increase of next higher harmonics term, reaches the maximum at a critical strength, then decreases when the next higher harmonics is larger. Our theoretical results show that the variation of the SC gap with the next higher harmonics can explain the anomalous behavior of the electron spectrum and different angle-resolved photoemission spectroscopy experimental results of different samples of electron-doped cuprate superconductors. Moreover, the magnitude of the SC gap can be suppressed by the next higher harmonics, which may be one of the reasons for the smaller SC gap in electron-doped cuprate superconductors. Obvious topological change happens in the SC gap at a critical strength of the next higher harmonics.

Computational Modeling of Tensile Stress Effects on the Structure and Stability of Prototypical Covalent and Layered Materials

Understanding the stability limit of crystalline materials under variable tensile stress conditions is of capital interest for technological applications. In this study, we present results from first-principles density functional theory calculations that quantitatively account for the response of selected covalent and layered materials to general stress conditions. In particular, we have evaluated the ideal strength along the main crystallographic directions of 3C and 2H polytypes of SiC, hexagonal ABA stacking of graphite and 2H-MoS 2 . Transverse superimposed stress on the tensile stress was taken into account in order to evaluate how the critical strength is affected by these multi-load conditions. In general, increasing transverse stress from negative to positive values leads to the expected decreasing of the critical strength. Few exceptions found in the compressive stress region correlate with the trends in the density of bonds along the directions with the unexpected behavior. In addition, we propose a modified spinodal equation of state able to accurately describe the calculated stress–strain curves. This analytical function is of general use and can also be applied to experimental data anticipating critical strengths and strain values, and for providing information on the energy stored in tensile stress processes.

Computational Modeling of Tensile Stress Effects on the Structure and Stability of Prototypical Covalent and Layered Materials

Understanding the stability limit of crystalline materials under variable tensile stress conditions is of capital interest for their technological applications. In this study, we present results from first-principles density functional theory calculations that quantitatively account for the response of selected covalent and layered materials to general stress conditions. In particular, we have evaluated the ideal strength along the main crystallographic directions of 3C and 2H polytypes of SiC, hexagonal ABA stacking of graphite and 2H-MoS2. Transverse superimposed stress on the tensile stress was taken into account in order to evaluate how the critical strength is affected by these multi-load conditions. In general, increasing transverse stress from negative to positive values leads to the expected decreasing of the critical strength. Few exceptions found in the compressive stress region correlate with the trends in the density of bonds along the directions with the unexpected behavior. In addition, we propose a modified spinodal equation of state able to accurately describe the calculated stress-strain curves. This analytical function is of general use and can also be applied to experimental data anticipating critical strengths and strains values and providing informattion on the energy stored in tensile stress processes.

Experimental Study of Low-Cycle Fatigue Behavior of a Welded Flange-Bolted Web Connection in Steel Moment-Resisting Frames

This paper describes an experimental investigation of the low-cycle fatigue (LCF) behavior of welded flange-bolted web (WFBW) connections, which are commonly employed in high-rise steel moment-resisting frames (MRFs) in Japan. The main parameters investigated in this study were (1) bolt configuration of the web connection and (2) steel grade. According to test results, LCF capacity depends on the slip behavior of different bolt configurations, even at relatively minor inelastic rotations. Slip behavior effects can be evaluated by the yield strength of the shear plate or the slip-critical strength; for specimens whose shear plate yield strength was designed to be higher than the slip-critical strength, LCF capacity showed that the upper limit can neglect slip behavior. Furthermore, it was shown that LCF behavior can be evaluated by the same fatigue curve in the relationship of fatigue capacity and beam rotation amplitude, regardless of steel yield stress.

Skin and Bone: Beauty as Critical Praxis

That so many hegemonic constructs have been devised to exoticize and belittle beauty should be evidence enough that something about beauty is devastating to power, something just below the skin. And in revealing patriarchy’s sleight of hand, we may begin to see that beauty is skin, deep as skin, moving into muscle, bone, marrow. This essay seeks to explore beauty as a critical praxis; not a gender-only matrix, beauty’s critical strength is in the conscious sociocultural construction of bodies, their colors, shapes, sizes, and abilities. Beauty as a critical praxis is a personally, politically, willfully wanton utopian performative. That so many hegemonic constructs have been devised to exoticize and belittle beauty should be evidence enough that something about beauty is devastating to power, something just below the skin. And in revealing patriarchy’s sleight of hand, we may begin to see that beauty is skin, deep as skin, moving into muscle, bone, marrow. This essay seeks to explore beauty as a critical praxis; not a gender-only matrix, beauty’s critical strength is in the conscious sociocultural construction of bodies, their colors, shapes, sizes, and abilities. Beauty as a critical praxis is a personally, politically, willfully wanton utopian performative.