Static Universe Research Articles

Review of Rosi Braidotti’s, Posthuman Feminism

Critiques to the universal condition of the human have defied the boundaries of the body and what is meant to be considered as “normal” or “neutral”, prompting the-so-called posthuman turn. This book, written by Rosi Braidotti, elaborates on the thought that “mainstream posthuman scholarship has neglected femist theory” (p. 2), postulating feminist theory as not only a contributor, but also as a precursor of the posthuman turn. Braidotti aims at offering a more sophisticated analysis of the reframing of the human as an embodied and embedded “heterogeneous assemblage” (p. 6), that understands the prismic nature of feminism and builds on a multiple stanpoints emergent from the birth of ecofeminism, feminist studies of technoscience, LGBTQ+ theories, black feminisms, decolonial feminisms, and Indigenous feminisms and that recognises such complexity within the structural socio-economic dynamics and upcoming environmental challenges that shape the subject.

On self-energy contributions near Berezinskii–Kosterlitz–Thouless transition in interacting homogeneous 2D Bose system

ABSTRACT We explore the consequences of including quantum corrections in an interacting 2D Bose system near Berezinskii–Kosterlitz–Thouless (BKT) transition. To go beyond mean-field theory and treat correlations, we use Matsubara Green's function method, and, following a previous novel approach, study features of the interacting Green's function just above the transition. We numerically obtain self-consistent solutions of boson self-energy to second order as well as higher order (re-summation of ladder and bubble diagrams) in the interaction strength, for the entire range of momentum, k, and compare our findings with analytic results in the limits of low- and high-k. Thereby, in the weak interaction limit, we retrieve the universal transition condition and calculate the universal scaling parameter (independent of interaction strength). The renormalised single-particle Green's function is found to decay algebraically at large distance r.

Torsion Fields Generated by the Quantum Effects of Macro-bodies

We generalize Einstein’s General Relativity (GR) by assuming that all matter (including macro-objects) has quantum effects. An appropriate theory to fulfill this task is Gauge Theory Gravity (GTG) developed by the Cambridge group. GTG is a “spin-torsion” theory, according to which, gravitational effects are described by a pair of gauge fields defined over a flat Minkowski background spacetime. The matter content is completely described by the Dirac spinor field, and the quantum effects of matter are identified as the spin tensor derived from the spinor field. The existence of the spin of matter results in the torsion field defined over spacetime. Torsion field plays the role of Bohmian quantum potential which turns out to be a kind of repulsive force as opposed to the gravitational potential which is attractive. The equivalence principle remains and essential in this theory so that GR is relegated to a locally approximate theory wherein the quantum effects (torsion) are negligible. As a toy model, we assume that the macro matter content can be described by the covariant Dirac equation and apply this theory to the simplest radially symmetric and static gravitational systems. Consequently, by virtue of the cosmological principle, we are led to a static universe model in which the Hubble redshifts arise from the torsion fields.

Towards a Radical Feminist Resignification of Vulnerability: A Critical Juxtaposition of Judith Butler’s Post-Structuralist Philosophy and Martha Fineman’s Legal Theory

This research article aims to theoretically reconstruct a positive feminist conceptualization of vulnerability via a thorough systematization and critical comparison of Martha Fineman’s socio-legal philosophy and Judith Butler’s post-structuralist ethico-political theory. Through the introduction, the reader becomes familiar with numerous interdisciplinary re-articulations of vulnerability within the realms of contemporary feminist theory. The second subsection illustrates Fineman’s vulnerability approach in terms of an alternative ontological paradigm deriving from the recognition of our fundamentally fragile universal condition. It explores Fineman vulnerability theory’s normative implications in relation to the legitimate political organization of democratic societies and the fair function of their central institutions. The third subsection systematizes the dual texture of the Butlerian radicalization of vulnerability as an existential condition of irreducible relationality and a socio-historically contextualized and differentially allocated distribution of precarity among differently gendered, racialized, sexualized and nationalized subjects. Incidentally, the article elucidates the differentiations between the Butlerian conceptions of vulnerability, precariousness, precarity and dispossession and additionally investigates Butler’s revolutionary constellation of vulnerability and resistance. In the third subsection, this article designates the similarities and divergences between the two vulnerability frameworks and critically evaluates their epistemological capacity to reconstitute a politically empowering conceptualization of vulnerability within the heart of contemporary feminist theory. To that end, the author develops a critical assessment of Fineman theory’s epistemological, political and conceptual limitations in regard of its gender-blind universalistic structure. The author conclusively argues that Butler’s two-fold vulnerability perspective entails more nuanced theoretical conceptions and more empowering political devices for contemporary feminist struggles.

Thermal Casimir Effect in the Einstein Universe with a Spherical Boundary

In the present paper, we investigate thermal fluctuation corrections to the vacuum energy at zero temperature of a conformally coupled massless scalar field, whose modes propagate in the Einstein universe with a spherical boundary, characterized by both Dirichlet and Neumann boundary conditions. Thus, we generalize the results found in the literature in this scenario, which has considered only the vacuum energy at zero temperature. To do this, we use the generalized zeta function method plus Abel-Plana formula and calculate the renormalized Casimir free energy as well as other thermodynamics quantities, namely, internal energy and entropy. For each one of them, we also investigate the limits of high and low temperatures. At high temperatures, we found that the renormalized Casimir free energy presents classical contributions, along with a logarithmic term. Also in this limit, the internal energy presents a classical contribution and the entropy a logarithmic term, in addition to a classical contribution as well. Conversely, at low temperatures, it is demonstrated that both the renormalized Casimir free energy and internal energy are dominated by the vacuum energy at zero temperature. It is also demonstrated that the entropy obeys the third law of thermodynamics.

Potential of emission reduction of a turbo-charged non-road diesel engine without aftertreatment under multiple operating scenarios

In this study, the bench test of a non-road diesel engine was conducted under universal conditions, non-road steady-state cycle (NRSC) and non-road transient cycle (NRTC). To reduce the raw emissions of the tested non-road diesel engine, some improvement measures, such as pre-injection, smoke limit, and intake throttle degree control strategy, were applied to the optimized engine. The experiment results showed that particulate matter (PM) emissions are reduced significantly at medium-high speed and low load. The maximum and average proportion of PM emissions reduction at 0–30% load and 1400–2200 r/min are 68.4% and 47.5%, respectively. However, the optimized nitrogen oxide (NOx) emissions are higher than that of the original engine, particularly under low load working conditions. Nevertheless, at medium-high speed and load, NOx emissions of the optimized engine were reduced. PM and NOx emissions decreased by 12.3% and 2.4%, respectively, under NRSC. Under NRTC, PM and NOx emissions decreased by 5.2% and 5.5%, respectively. Unburned hydrocarbon (HC) and carbon monoxide (CO) were always maintained at extremely low emission levels. Furthermore, the fuel consumption almost remained constant under all operating conditions. Thus, this study demonstrates the emission reduction potential in non-road diesel engines without considerable payment.

Testing Dependencies and Inference Rules in Databases

The process of testing dependencies and inference rules can be used in two ways. First, testing allows verification hypotheses about unknown inference rules. The main goal, in this case, is to search for the relation - a counterexample that illustrates the feasibility of the initial dependencies and contradicts the consequence. The found counterexample refutes the hypothesis, the absence of a counterexample allows searching for a generalization of the rule and conditions for its feasibility (logically imply). Testing cannot be used as a proof of the feasibility of inference rules, since the process of generalization requires the search for universal inference conditions for each rule, which cannot be programmed, since even the form of these conditions is unknown. Secondly, when designing a particular database, it may be necessary to test the feasibility of a rule for which there is no theoretical justification. Such a situation can take place in the presence of anomalies in the superkey. The solution to this problem is based on using join dependency inference rules. For these dependencies, a complete system of rules (axioms) has not yet been found. This paper discusses: 1) a technique for testing inference rules using the example of join dependencies, 2) a scheme of a testing algorithm is proposed, 3) some hypotheses are considered for which there are no counterexamples and inference rules, 4) an example of using testing when searching for a correct decomposition of a superkey is proposed.

Conformal actions on the Einstein universe

In this paper we study nontransitive irreducible and transitive reducible conformal actions on the Einstein universe Ein1,n−1. In either case, we give the explicit representation of the acting group in O(2,n). When the action is nontransitive and irreducible, we determine the dimension and the causal character of the induced orbits in the nullcone of R2,n and then in the Einstein universe. We prove that any such nontransitive action induces an open orbit in the Einstein universe and that the orbit space is finite.

An extreme environment-tolerant anti-icing coating

Undesired ice accumulation on outdoor infrastructures causes serious economic and safety issues, inducing the urgent demand of anti-icing coatings. However, the outdoor equipment inevitably suffers from various extreme environments, resulting in a challenge for anti-icing coatings to maintain surface structures and material properties that directly affect anti-icing performance. Herein, we develop an anti-icing coating that can tolerate a variety of extreme environments, including ultra-low (-196 ℃) or high temperature (200 ℃), strong acid (pH = 0) or alkali (pH = 14), 168-h ultraviolet (∼6-month sunlight) exposure, and 200-cycle sandpaper grinding. The tough coating can remain intact and maintain deicing performance owing to the incorporation of fluorinated amphiphilic copolymers and photo-thermal nanocarbon fibers in PDMS matrix. The coating can significantly decrease ice nucleation temperature (<-26 ℃), increase icing delay time (∼46-fold delay), and reduce ice adhesion strength (∼17.7 kPa), suggesting both excellent anti-icing and energy-saving deicing performance. This coating is highly promising to outdoor anti-icing applications for universal conditions.

Antiulcer Effect of Senna multiglandulosa via Increased Secretion of Mucus and Nonprotein Sulfhydryl Groups in an Experimental Murine Model.

Peptic ulcer is a universal condition that is a public health problem due to its prevalence, risk of complications and socioeconomic impact. This study aimed to determine the antiulcer effect of the hydroalcoholic extract from Senna multiglandulosa leaves against ethanol-induced gastric ulcer in rats. Thirty-six male albino Holtzman rats were assigned to six groups. Group I received physiological saline (PS) at doses of 10 mL/kg; group II: ethanol (PS + ethanol 5 mL/kg); group III; omeprazole 100 mg/kg/day (gold standard); groups IV, V and VI received doses of 100, 250 and 500 mg/kg/day of S. multiglandulosa extract, respectively. The stomach was removed to determine the ulcerative lesions and two sections of the glandular zone to carry out the analysis of the gastric mucus and sulfhydryl groups content. As result, S. multiglandulosa at doses of 250 and 500 mg/kg produced a significant decrease of the injured area, with values of 46.28 ± 7.95 mm2 and 6.91 ± 2.48 mm2, respectively (P < 0.001). The protective effect was showed at dose of 500 mg/kg (92.27%) and a significant increase in the production of mucus with a value of 83.13 ± 13.09 mg/mL/g of tissue (61.14%). The production of nonprotein sulfhydryl groups (NP-SG) also increased significantly at the three evaluated doses, being 250.34 ± 21.16 μg/g tissue at dose of 500 mg/kg (119.94%). It is concluded that S. multiglandulosa extract protected against ethanol-induced gastric ulcer due to increased gastric mucus secretion and its antioxidant activity due to the generation of nonprotein sulfhydryl groups.

Einstein static universe and its stability in generalized Rastall gravity

The Einstein static (ES) state is a good candidate for describing the very early universe in terms of a regular cosmological model in which the Big Bang singularity is avoided. In the present study we propose an ES solution in the framework of generalized Rastall gravity (GRG), a modified version of original Rastall theory in which the coupling parameter is allowed to vary with respect to the spacetime coordinates. Introducing an ansatz for the Rastall parameter, existence and the corresponding stability of the solutions are investigated. We show that the GRG is capable of describing a stable singularity-free state for the universe. The problem of transition from an ES to an inflationary state is also addressed. We find that a time variation of the equation of state parameter from values lying in the range |w|<1/3 to the value w=−1/3 can give rise to such a phase transition. The vector and tensor perturbations around the ES solution are studied, as well. In the case of GRG, the vector perturbations remain frozen, nevertheless, the tenor perturbations can grow in such a way that the ES solution remains stable provided the ratio of Rastall gravitational constant to the Einsteinian one always exceeds a minimum value for each tensor mode.

The quantum theory of time: a calculus for q-numbers.

In quantum theory, physical systems are usually assumed to evolve relative to a c-number time. This c-number time is unphysical and has turned out to be unnecessary for explaining dynamics: in the timeless approach to quantum theory developed by Page & Wootters 1983 Phys. Rev. D 27, 2885. (doi:10.1103/PhysRevD.27.2885), subsystems of a stationary universe can instead evolve relative to a ‘clock', which is a quantum system with a q-number time observable. Page & Wootters formulated their construction in the Schrödinger picture, which left open the possibility that the c-number time still plays an explanatory role in the Heisenberg picture. I formulate their construction in the Heisenberg picture and demonstrate how to eliminate c-number time from that picture, too. When the Page–Wootters construction is formulated in the Heisenberg picture, the descriptors of physical systems are functions of the clock's q-number time, and derivatives with respect to this q-number time can be defined in terms of the clock's algebra of observables, which results in a calculus for q-numbers.

Introduction

Introduction

Bringing the Mechanistic Approach Back to Life: A Systematic Review of the Experimental Evidence for Coexistence and Four of Its Classical Mechanisms

Coexistence theories develop rapidly at the ecology forefront suffering from interdisciplinary gaps and a lack of universality. The modern coexistence theory (MCT) was developed to address these deficiencies by formulating the universal conditions for coexistence. However, despite this theory's mechanistic foundation, initially, it has only rarely been used to determine the exact mechanisms that govern the competitive outcome. Recent theoretical developments have made MCT more accessible to experimentalists, but they can be challenging in practice. We propose that a comprehensive understanding of species co-occurrence patterns in nature can be reached by complementing the phenomenological approach with both the mechanistic view of MCT and coexistence experiments of the type that prevailed from the 1970s to the 2010s, which focused on specific mechanisms (designated the “mechanistic approach”). As a first step in this direction, we conducted a systematic review of the literature from 1967 to 2020, covering mechanistic experiments for invasibility—the criterion for species coexistence—and the best-studied classical coexistence mechanisms, namely, resource-ratio, natural enemy partitioning, frequency-dependent exploitation by generalist enemies, and the storage effect. The goals of the review were to evaluate (i) the percentage of the abovementioned mechanistic experiments that satisfy the theoretical criteria (designated “eligible studies”), (ii) the scope of these eligible studies, and (iii) their level of support for the theoretical predictions, and to identify their (iv) overarching implications and (v) research gaps. Through examination of 2,510 publications, the review reveals that almost 50 years after the theoretical formulations of the above four coexistence mechanisms, we still lack sufficient evidence to reveal the prevalence of coexistence and of each of the coexistence mechanisms, and to assess the dependency of the mechanisms on the natural history of the competing organisms. By highlighting, on the one hand, the overarching implications of the mechanistic approach to coexistence, and on the other hand, current research gaps, and by offering ways to bridge these gaps in the future, we seek to bring the mechanistic approach back to life.

Anosov representations as holonomies of globally hyperbolic spatially compact conformally flat spacetimes

We study the link between Anosov representations and (G, X)-structure on spacetimes with \(G = O_0(2,n)\) and X is the Einstein universe \(Ein_{1,n-1}\) (\(n \ge 3\)), namely conformally flat spacetimes. Let \(\varGamma \) be a Gromov hyperbolic group and let \(\rho : \varGamma \rightarrow O_0(2,n)\) be a \(P_1\)-Anosov representation as defined in [14]. We suppose that the limit set is an acausal subset in \(Ein_{1,n-1}\). Our first result is that \(\rho \) is the holonomy of a globally hyperbolic spatially compact maximal (abbrev. GHCM) conformally flat spacetime of dimension n. This comes in the continuity of Barbot-Mérigot work in anti-de Sitter geometry Barbot and Mérigot (Groups Geometry Dynamics 6(3): 441–483 2012): they proved that when the limit set is a topological \((n-1)\)-sphere then \(\rho \) is the holonomy of a GHCM spacetime locally modeled on the anti-de Sitter spacetime \(AdS_{1,n}\). Our second result extends this last one and state that, except in this particular case, \(\rho \) is the holonomy of a strongly causal AdS-spacetime of dimension \((n+1)\) which is a BTZ-black hole Banados et al. (Phys Rev D Part Fields 48(4):1506–1525 1993), Banados et al. (Phys Rev Lett 69(13):1849–1851 1992), Barbot T (Adv Theor Math Phys 12:1209–1257 2005).

Static and dynamic Melvin universes

We briefly review the known properties of Melvin's magnetic universe and study the propagation of test charged matter waves in this static spacetime. Moreover, the possible correspondence between the wave perturbations on the background Melvin universe and the motion of charged test particles is discussed. Next, we explore a simple scenario for turning Melvin's static universe into one that undergoes gravitational collapse. In the resulting dynamic gravitational field, the formation of cosmic double-jet configurations is emphasized.

Co78Si8B14 metallic glass: A highly efficient and ultra-sustainable Fenton-like catalyst in degrading wastewater under universal pH conditions

Overcoming the pH limitation and increasing the catalyst reusability remain pressing demands for metallic glass (MG) in wastewater remediation. Herein, Co78Si8B14 MG ribbons are used to degrade dye wastewater by activating hydrogen peroxide (H2O2) as Fenton-like catalysts. The Co-based MG catalysts exhibit high degradation efficiency under both acidic and alkaline conditions, and the kinetic reaction rate at pH 10 (0.176 min−1) and pH 4 (0.089 min−1) is 5.9 and 1.2 times higher than that of the extensively studied Fe-based MG catalysts, respectively. Impressively, the Co-based MG catalysts can be reused up to 20–60 times at universal pH conditions, demonstrating fairly good reusability. The newly discovered Co-based MG catalysts do not follow the classical Fenton reactions with H2O2 the way Fe-based MGs do. In an acid environment, hydroxyl radicals play a dominant role in the degradation, while in an alkaline environment, the effect of hydroxyl radicals is weakened, and Co3+ ions exert a relatively major function on the degradation. The excellent performance in catalytic activity and reusability at universal pH conditions of the Co-based MGs will inspire the development of MGs in wastewater treatment.

Time evolution of the inside of the black hole’s horizon

We consider the Wheeler–DeWitt equation near the horizon of the black hole where the entangled vacuum state is chosen as the static universe state. Then, using the entangled property of the vacuum state, we investigate the dynamical evolution of the subsystems, namely inside and outside of the horizon

Quantum Capacity and Vacuum Compressibility of Spacetime: Thermal Fields

An important yet perplexing result from work in the 1990s and 2000s is the near-unity value of the ratio of fluctuations in the vacuum energy density of quantum fields to the mean in a collection of generic spacetimes. This was carried out by way of calculating the noise kernels which are the correlators of the stress-energy tensor of quantum fields. In this paper, we revisit this issue via a quantum thermodynamics approach, by calculating two quintessential thermodynamic quantities: the heat capacity and the quantum compressibility of some model geometries filled with a quantum field at high and low temperatures. This is because heat capacity at constant volume gives a measure of the fluctuations of the energy density to the mean. When this ratio approaches or exceeds unity, the validity of the canonical distribution is called into question. Likewise, a system’s compressibility at constant pressure is a criterion for the validity of grand canonical ensemble. We derive the free energy density and, from it, obtain the expressions for these two thermodynamic quantities for thermal and quantum fields in 2d Casimir space, 2d Einstein cylinder and 4d (S1×S3 ) Einstein universe. To examine the dependence on the dimensionality of space, for completeness, we have also derived these thermodynamic quantities for the Einstein universes with even-spatial dimensions: S1×S2 and S1×S4. With this array of spacetimes we can investigate the thermodynamic stability of quantum matter fields in them and make some qualitative observations on the compatibility condition for the co-existence between quantum fields and spacetimes, a fundamental issue in the quantum and gravitation conundrum.

When vulnerability got mainstream: Reading the pandemic through disability and illness

Since its outbreak, the COVID-19 pandemic has generated discourses and practices that directly refer to the semantic universe usually connected to disability and illness. Words such as ‘pre-existing conditions’, ‘risk groups’, ‘accessibility’, and ‘vulnerability’ have become everyday elements of official and informal communications across the globe. In this article, I explore the contradictions that arise from such uses through the lens of crip studies. In the first part, I observe how the idea of vulnerability became mainstream, moving from being usually attached to disability and illness to being depicted as a universal condition. Such a shift serves the double purpose of reinstating the predominance of able-bodiedness as the preferable normalcy and invisibilising the particular conditions of disabled and chronically ill people in the pandemic. In the second part, I discuss the perverse use of the expressions ‘risk group’ and ‘underlying conditions’ as biopolitical tools to reinforce already existing forms of oppression. The third part comprises a reflection on accessibility and the sudden advent of working-from-home. Finally, I reflect on confinement and interdependence as key concepts to draft a politics of transformation that moves from disability and chronic illness to include all experiences of intersectional oppression. As other markers of oppression, illness and disability can determine the possibilities of survival through the crisis, not only because they are linked to bodily fragility but also because of the systemic violence they are immersed in. The knowledge produced from a place of vulnerability can hence show interesting elements to better understand the challenges of this pandemic through an intersectional perspective.