Loop Effects Research Articles

Dislocation loop and irradiation-induced synergistic-competitive mechanism in Cu-rich precipitates: a phase-field study

Both irradiation and dislocations have been proposed as routes to rationally manipulate spatial distribution and micromorphology of precipitate. An interesting effect emerges in Fe–10at.%Cu–3at.%Mn–1.5at.%Ni–1.5at.%Al alloy due to the synergistic-competitive roles of dislocation loop and irradiation. Base on cascade mixing, vacancy-interstitial atoms and dislocation stress field model, we examine nucleation and growth dynamics of Cu-rich precipitates, where both dislocation loop and irradiation act in conjunction. Analytical treatments identify regimes, where the distribution of elements and point defects due to irradiation and dislocations are specific to the Cu-rich precipitates. Simulation results reveal that density, size and distribution of Cu-rich precipitates are a manifestation of the competing effects of the dislocation loop and the irradiation rate. More specifically, the dislocation loop preferentially assists the formation of precipitates and new dislocations at lower irradiation rates. Only the irradiation induces the formation of Cu-rich precipitates with the irradiation rate continues to increase. Equipped with molecular dynamics, where reproduces major interaction features of the solutes with point defects under displacement cascade, can verify multi-component morphologies of Cu-rich precipitates. This modeling framework provides an avenue to explore the role of dislocation loop and irradiation on the microstructural evolution of Cu-rich precipitates.

A just energy transition for Indigenous peoples: From ideal deliberation to fairness in Canada and Australia

In response to the global climate crisis, renewable energy projects are being developed on Indigenous territories. As renewable energy sources are not without social and ecological impacts, it is crucial to consider who benefits from these projects and who bears the consequences. In settler states such as Canada and Australia, the power dynamics are affecting the role of Indigenous peoples in the energy transitions. This paper proposes a theoretical framework for a just energy transition (JET) based on a comprehensive literature review of justice movements, energy transitions, and Indigenous experiences in Canada and Australia. The literature on environmental, climate, and energy justice examines three dimensions of justice: procedural, distributional, and recognition. While these dimensions offer important perspectives for our analysis, they are not sufficient on their own. This paper argues that promoting justice for Indigenous knowledge renewal is crucial for establishing a fair energy future. In addition to knowledge renewal, our framework comprises two more JET components: socioeconomic impact distribution, and procedural power. We argue that the JET components are deeply interrelated in an insidious loop effect. This means that all justice issues have the same roots, perpetuated by the historical consequences of colonisation. The question is how to simultaneously address them to transform a negative cycle into a positive one. Drawing on Indigenous rights in Canada and Australia this paper highlights the importance of improved bilateral communication strategies to break the insidious loop effect. Before discussing project strategies, it is crucial to consider the fairness of the decision-making process.

Justification for coercion in a public health crisis: not just a matter of individual harm.

The COVID pandemic was an exceptional public health situation - which brought with it unprecedented restrictions across the global populace. But what was it about this pandemic which caused us to implement such drastic restrictions on liberty? Much of the ethical debate on restrictive measures such as lockdowns and vaccine requirements focused on the potential harm that individuals cause to other individuals by the risk of infection. I will suggest that this may come from a reliance on J.S. Mill's harm principle as providing the ultimate justification for coercion - i.e., the well-accepted principle that state coercion is justified in order to prevent the imposition of unacceptable risk of harm to others. Though there have been attempts, in the wider public health ethics literature, to use the harm principle as a basis for restricting contribution to collective harms, I will suggest that these attempts cannot rely on the harm principle alone. I will then turn to the ways in which an individual-based line of reasoning does not capture a distinctive sort of harm posed by the COVID pandemic (and others like it): the potential failure of healthcare systems. I will draw out three ways in which a focus on the harm that an individual poses to another individual fails to capture the full scope of harm wrought by the collapse of healthcare systems. First, it can't adequately capture the cumulative and "looping effects" of the harm caused by strained healthcare systems. Second, it fails to capture the widespread ripple effects the failure of a central societal institution can have on other institutions. And third, the failure of a healthcare system can impose "psychic costs", affecting the moral character of all members of society, reducing trust in institutions, and potentially posing an existential threat to the fabric of society. Finally, I will sketch some implications of the recognition of this distinctive sort of harm for the justification of coercive public health measures.

Gravitational wave effects and phenomenology of a two-component dark matter model

We study an extension of the Standard Model (SM) which could have two candidates for dark matter (DM) including a Dirac fermion and a vector dark matter (VDM) under a new U(1) gauge group in the hidden sector. The model is classically scale-invariant and the electroweak symmetry breaks because of loop effects. We investigate the parameter space allowed by current experimental constraints and phenomenological bounds. We probe the parameter space of the model in the mass range 1<MV<5000\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1< M_V<5000$$\\end{document} GeV and 1<Mψ<5000\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1<M_{\\psi }<5000$$\\end{document} GeV. It has been shown that there are many points in this mass range that are in agreement with all phenomenological constraints. The electroweak phase transition has been discussed and it has been shown that there is region in the parameter space of the model consistent with DM relic density and direct detection constraints that, at the same time, can lead to first-order electroweak phase transition. The gravitational waves produced during the phase transition could be probed by future space-based interferometers such as LISA and BBO.

Effect of microstructure on sag resistance of ultra-high strength spring steel evaluated by hysteresis loop

Sag refers to the reduction in the free height of coil springs during actual usage, hence sag resistance is one of the crucial properties of spring steel and its improvement is essential for prolonging the service life of springs. However, limited research has been conducted on the effect of microstructure on sag resistance in recent years. This study aims to investigate the relationship between microstructure and sag resistance in 65SiCrV6 spring steel. The steel was quenched from various temperatures to obtain microstructures with varying sub-block size, and tempered at different temperatures to obtain microstructures with distinct tempered carbides morphology. The microstructures were characterized and the sag resistance was evaluated by hysteresis loop effect formed during cyclic tensile test. The results revealed that smaller sub-block sizes of martensite and higher proportions of high-angle grain boundary (HAGB) are beneficial for improving sag resistance. Incoherent granular cementite precipitated in the tempered microstructure improves sag resistance by enhancing interactions with dislocations, and coarsened cementite does not reduce the sag resistance due to the generation of back stress in heterogeneous microstructure. The hysteresis loop effect resulting from heterostructure as well as interactions between dislocations and tempered carbides increases with rising tempering temperature until it reaches a saturation state. This study highlights the importance of optimizing the microstructure with both small sub-block size and incoherent cementite precipitation through appropriate heat treatment process to enhance sag resistance, meanwhile provides valuable insights into understanding the micromechanism of sag resistance in spring steel.

Trans Tricksters, Looping Effects, and Gender Diagnoses as Containment

This essay examines how medical rhetorics helped justify the recent torrent of anti-trans legislation. Beginning with the “legitimacy wars” between psychiatry and psychology, I trace how competing disciplines established their own expertise by denying trans patients’ agency and self-knowledge. After identifying the “trans trickster” trope that emerges from these rhetorics, I trace how the trans trickster haunts arguments used to ban gender-affirming health care and sports participation for trans youth. I draw from sociologist Ian Hacking’s “looping effects” to explain how medical logics affect public perception and how those understandings loop back into medical research. The binary, linear models of gender transition established by trans medicine helped justify cisnormative policies around transgender identity, which in turn restricted further scientific inquiry such that more imaginative gender formations remain illegible. To conclude, I argue that medical paradigms work in relation with trans imagination would expand scientific explorations of human diversity, and that those understandings too could loop through public policy and perception.

Janus faced: The co-evolution of war and peace in the human species.

The human species presents a paradox. No other species possesses the propensity to carry out coalitionary lethal attacks on adult conspecifics coupled with the inclination to establish peaceful relations with genetically unrelated groups. What explains this seemingly contradictory feature? Existing perspectives, the "deep roots" and "shallow roots" of war theses, fail to capture the plasticity of human intergroup behaviors, spanning from peaceful cooperation to warfare. By contrast, this article argues that peace and war have both deep roots, and they co-evolved through an incremental process over several million years. On the one hand, humans inherited the propensity for coalitionary lethal violence from their chimpanzee-like ancestor. Specifically, having first inherited the skills to engage in cooperative hunting, they gradually repurposed such capacity to execute coalitionary killings of adult conspecifics and subsequently enhanced it through technological innovations like the use of weapons. On the other hand, they underwent a process of cumulative cultural evolution and, subsequently, of self-domestication which led to heightened cooperative communication and increased prosocial behavior within and between groups. The combination of these two biocultural evolutionary processes-coupled with feedback loop effects between self-domestication and Pleistocene environmental variability-considerably broadened the human intergroup behavioral repertoire, thereby producing the distinctive combination of conflictual and peaceful intergroup relations that characterizes our species. To substantiate this argument, the article synthesizes and integrates the findings from a variety of disciplines, leveraging evidence from evolutionary anthropology, primatology, archeology, paleo-genetics, and paleo-climatology.

Effect of loops on the mean-square displacement of Rouse-model chromatin.

Chromatin polymer dynamics are commonly described using the classical Rouse model. The subsequent discovery, however, of intermediate-scale chromatin organization known as topologically associating domains (TADs) in experimental Hi-C contact maps for chromosomes across the tree of life, together with the success of loop extrusion factor (LEF) model in explaining TAD formation, motivates efforts to understand the effect of loops and loop extrusion on chromatin dynamics. This paper seeks to fulfill this need by combining LEF-model simulations with extended Rouse-model polymer simulations to investigate the dynamics of chromatin with loops and dynamic loop extrusion. We show that loops significantly suppress the averaged mean-square displacement (MSD) of a gene locus, consistent with recent experiments that track fluorescently labeled chromatin loci. We also find that loops reduce the MSD's stretching exponent from the classical Rouse-model value of 1/2 to a loop-density-dependent value in the 0.45-0.40 range. Remarkably, stretching exponent values in this range have also been observed in recent experiments [Weber et al., Phys. Rev. Lett. 104, 238102 (2010)0031-900710.1103/PhysRevLett.104.238102; Bailey et al., Mol. Biol. Cell 34, ar78 (2023)1059-152410.1091/mbc.E23-04-0119]. We also show that the dynamics of loop extrusion itself negligibly affects chromatin mobility. By studying static "rosette" loop configurations, we also demonstrate that chromatin MSDs and stretching exponents depend on the location of the locus in question relative to the position of the loops and on the local friction environment.

Impedance remodeling control strategy of grid-connected inverter with inertia-damping phase-locked loop under extremely weak grid

The operation of the grid-connected inverter (GCI) in weak grid conditions presents a risk of instability due to the presence of high grid impedance and the negative impedance effect of the phase-locked loop (PLL). In response to this issue, this paper introduces an impedance remodeling control strategy for the GCI utilizing the inertia-damping phase-locked loop (ID-PLL). Firstly, the proposed ID-PLL exhibits certain inertia and damping properties in comparison to the traditional PLL (T-PLL), resulting in an enhanced phase margin of the GCI system's equivalent output impedance. Consequently, the adaptation range of the grid impedance increases from 12mH (SCR = 3.00) to 24mH (SCR = 1.37). Next, from the perspective of impedance analysis, this study remodels the PLL impedance and inverter control loop impedance, further improving the amplitude and phase margin of the system's output impedance. As a result, the adaptation range of the grid impedance extends to 33mH (SCR = 1.00), and the transition of grid-connected currents becomes smooth and free of overshoot. Finally, the effectiveness of the proposed control strategy is validated through theoretical analysis and experimental verification.

Assessing passive thermosyphon solar water heater as low-cost, sustainable water disinfection technology: Leveraging the Germicidal effect of copper and thermal convection loops

This study investigated the passive thermosyphon solar water heater (TSWH) as a domestic size point-of-use water disinfection treatment system for inactivating bacteria by utilizing both the germicidal properties of copper in heat exchanger and the heat generated in thermal convection loops. Additionally, life cycle analysis and manufacturing cost analysis were conducted to reveal its environmental and economic benefits. Initially, the germicidal capacity of copper tube against E. coli and total coliform in rapidly flowing polluted water was tested in laboratory settings with contact times ranging from 1.5 to 94 min. Without any additional heat, the copper tubes achieved 99.9% (log 3.01) removal of E. coli, and 99.24% (log 2.12) removal of total coliform after 94 min of contact. In the presence of heat (50–80 ºC), complete removal of the bacteria was achieved after only 1.5 mins of contact time at 50ºC. A domestic-sized passive TSWH with a copper tube heat exchanger was evaluated for disinfecting 20 L/day of microbiologically polluted tap water and synthetic groundwater in a field study. The average contact time of polluted water in copper tube heat exchanger was 5.58±1.2 min in the morning (with an outlet water temperature of 87.3 ºC), and 11.83±1.41 min in the afternoon (with an outlet water temperature of 78±5.1 ºC). These contact times and temperatures, achieved throughout the year, were sufficient to meet the required minimum for complete bacterial removal in the synthetic groundwater. Importantly, the system achieved complete inactivation of pathogens at pasteurization temperatures below 75 ºC, relying solely on the combined effect of copper and thermal convection loops, without pumps or electricity. Compared to an active TSWH using circulating pumps and controls, the passive system generated 62.2% less green house gas, had 55.5% lower cumulative energy demand and cost 323.3 $ compared to 544.64 $. Highlighting significant economic and environmental benefits, the passive TSWH offers a promising solution for disinfecting water in low-income areas with limited access to safe water.

Unitarity bounds on the massive spin-2 particle explanation of muon g-2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$g-2$$\\end{document} anomaly

Motivated by the long-standing discrepancy between the Standard Model prediction and the experimental measurement of the muon magnetic dipole moment, we have recently proposed to interpret this muon g-2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$g-2$$\\end{document} anomaly in terms of the loop effect induced by a new massive spin-2 field G. In the present paper, we investigate the unitarity bounds on this scenario. We calculate the s-wave projected amplitudes for two-body elastic scatterings of charged leptons and photons mediated by G at high energies for all possible initial and final helicity states. By imposing the condition of the perturbative unitarity, we obtain the analytic constraints on the charged-lepton-G and photon-G couplings. We then apply our results to constrain the parameter space relevant to the explanation of the muon g-2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$g-2$$\\end{document} anomaly.

Looping effects, settler colonialism, and the indigenous child removal system

ABSTRACT Between 1950 and 1985, a period now referred to as the “Sixties Scoop”, over 24,000 Indigenous and Inuit children were removed from their families and placed into primarily non-Indigenous foster and adoptive homes across Canada. Whereas the Residential school system was explicitly racist and genocidal in its orientation, the Sixties Scoop racism was cloaked in accusations of neglect and child-saving rhetoric. Drawing on Hacking’s concept of looping effects, we examine how social workers classify their work and the Indigenous children they removed from their homes. We analyse sixteen interviews with social workers working in child welfare during the Sixties Scoop who were involved with the removal of Indigenous children. This article links broader systems that are fraught with racism, to the rank-and-file individuals tasked with carrying out child protection policies, and it probes the interpretations and classifications used both then and now to understand Indigenous child removal.

Transient Synchronization Stability Analysis of Grid-Following Converter Considering the Coupling Effect of Current Loop and Phase Locked Loop

Transient Synchronization Stability Analysis of Grid-Following Converter Considering the Coupling Effect of Current Loop and Phase Locked Loop

Phantom chain simulations for fracture of end-linking networks

Despite numerous studies, the relationship between network structure and fracture remains unclear. In this study, the fracture properties of end-linking networks were compared with those of loop-free analogs made from star prepolymers by performing phantom chain simulations. The networks were created from equilibrated sols of stoichiometric mixtures of linear prepolymers and f-functional linkers through end-linking reactions using Brownian dynamics schemes. The examined networks, with various f values (between 3 and 8) and strand-connection rates (φs), were evaluated in terms of the primary loop fraction and the cycle rank ξ. These structural characteristics were consistent with mean-field theories that assume independent reactions. Energy minimization and uniaxial stretch were applied to the networks until they broke without Brownian motion. The fracture characteristics, including strain at break (εb), stress at break (σb), and work for fracture (Wb), were obtained from stress-strain curves. The end-linking networks exhibited larger εb and smaller σb and Wb than those for star networks due to primary loops, at the same set of f and φs. However, εb, σb/νbr and Wb/νbr (with νbr being the branch point density) lie on the same master curves as those for star networks if they are plotted against ξ. This result implies that the fracture of end-linking networks is essentially the same as that for star analogs, and the effects of primary loops are embedded in ξ.

Primordial perturbations from ultra-slow-roll single-field inflation with quantum loop effects

It is known that the single-field inflation with a transient ultra-slow-roll phase can produce a large curvature perturbation at small scales for the formation of primordial black holes. In our previous work, we have considered quantum loop corrections to the curvature perturbation and found that the growth of these small-scale modes would affect the curvature perturbation at large scales probed by cosmic microwave background observation. In this work, we will further derive the constraints on the growing modes in the transition between the slow-roll and the ultra-slow-roll phases under the effect of the loop corrections. Our results would help clarify the recent controversy on whether or not the primordial-black-hole formation from the single-field inflation is ruled out at one-loop level.

One-loop effective action up to dimension eight: Integrating out heavy fermion(s)

We present the universal one-loop effective action up to dimension eight after integrating out heavy fermion(s) using the Heat-Kernel method. We have discussed how the Dirac operator being a weak elliptic operator, the fermionic operator still can be written in the form of a strong elliptic one such that the Heat-Kernel coefficients can be used to compute the fermionic effective action. This action captures the footprint of both the CP conserving as well as violating UV interactions. As it does not rely on the specific forms of either UV or low energy theories, can be applicable for a very generic action. Our result encapsulates the effects of heavy fermion loop through Yukawa couplings only.

Gravitational waves from composite dark sectors

We study under which conditions a first-order phase transition in a composite dark sector can yield an observable stochastic gravitational-wave signal. To this end, we employ the Linear-Sigma model featuring Nf = 3, 4, 5 flavours and perform a Cornwall-Jackiw-Tomboulis computation also accounting for the effects of the Polyakov loop. The model allows us to investigate the chiral phase transition in regimes that can mimic QCD-like theories incorporating in addition composite dynamics associated with the effects of confinement-deconfinement phase transition. A further benefit of this approach is that it allows to study the limit in which the effective interactions are weak. We show that strong first-order phase transitions occur for weak effective couplings of the composite sector leading to gravitational-wave signals potentially detectable at future experimental facilities.

Reactivity in the human sciences

The reactions that science triggers on the people it studies, describes, or theorises about, can affect the science itself and its claims to knowledge. This phenomenon, which we call reactivity, has been discussed in many different areas of the social sciences and the philosophy of science, falling under different rubrics such as the Hawthorne effect, self-fulfilling prophecies, the looping effects of human kinds, the performativity of models, observer effects, experimenter effects and experimenter demand effects. In this paper we review state-of-the-art research that falls under the remit of the philosophy of reactivity by considering ontological, epistemic and moral issues that reactivity raises. Along the way, we devote special attention to articles belonging to this journal's Topical Collection entitled “Reactivity in the Human Sciences”.

Self-Measurement of the Admittance Matrix of AC–DC Power Converter by Internal Harmonic Injection

Frequency-domain impedance or admittance model is widely applied to analyze harmonic stability of power electronic converters. Conventionally, the converter impedance is modeled holistically, without exhibiting the sole effect of different control and phase-locked loop (PLL). Besides, harmonic voltage or current injection external to the converter is usually adopted, which involves dedicated equipment and introduces unexpected inner impedance. In this paper, the response of voltage perturbation upon AC-DC power converter along various voltage signal flow paths is analyzed, based on superposition principle. Each part of admittance and its effect on stability can therefore be quantified explicitly. By injecting harmonic perturbation through the identified paths within the converter controller, each part of admittances, with and without the concerned control or PLL blocks, are measured and summed to be the total admittance. Harmonic voltage mitigation control implemented on a grid-forming converter creates an ideal grid with constant voltage and nearly zero inner impedance at the injected harmonic frequency. The proposed admittance analysis and measurement is successfully applied to power converter with different PLL, voltage feedforward, output power control, DC voltage control and grid-forming cascaded control. Effectiveness of the analysis and the proposed admittance measurement approach are validated by comprehensive simulation and hardware test.

Water-energy-food nexus efficiency and its factor analysis in China: A dynamic series-loop DDF model

This paper presents an analysis of the water-energy-food nexus (WEFN) system, focusing on its interlinked structure and dynamic characteristics. This paper proposes a dynamic series-loop data envelopment analysis (DEA) model with a directional distance function for measuring WEFN efficiency in China. A spatial Durbin model is constructed to investigate the impact of extreme temperatures on WEFN efficiency. The results are as follows. (1) Compared with the black-box DEA model and series network DEA model, a series-loop network DEA model can reflect the “networking effect” and “looping effect” in the WEFN system. (2) The WEFN system performs well with an average series-loop efficiency of 0.875, but the efficiency of the water subsystem scores low and needs improvement. (3) At the national level, extremely high and low temperatures have no significant effect on the WEFN efficiency in local or adjacent provinces, whereas average temperature promotes the WEFN efficiency in local provinces but hinders it in neighboring provinces. In the regions with a low temperature difference, average temperature has no impact on the WEFN efficiency of both the province itself and its neighboring provinces. Overall, this study provides valuable insights into the complex interlinkages within the WEFN system and highlights the importance of considering these relationships when improving the system efficiency.