domain of validity
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2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
G. Kaplanek ◽  
C.P. Burgess ◽  
R. Holman

Abstract Effective theories are being developed for fields outside black holes, often with an unusual open-system feel due to the influence of large number of degrees of freedom that lie out of reach beyond the horizon. What is often difficult when interpreting such theories is the absence of comparisons to simpler systems that share these features. We propose here such a simple model, involving a single external scalar field that mixes in a limited region of space with a ‘hotspot’ containing a large number of hot internal degrees of freedom. Since the model is at heart gaussian it can be solved explicitly, and we do so for the mode functions and correlation functions for the external field once the hotspot fields are traced out. We compare with calculations that work perturbatively in the mixing parameter, and by doing so can precisely identify its domain of validity. We also show how renormalization-group EFT methods can allow some perturbative contributions to be resummed beyond leading order, verifying the result using the exact expression.


2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Daniel Elander ◽  
Michele Frigerio ◽  
Marc Knecht ◽  
Jean-Loïc Kneur

Abstract We study strongly-coupled, approximately scale-invariant gauge theories, which develop a mass gap in the infrared. We argue that a large number of fermion flavours is most suitable to provide an ultraviolet completion for the composite Higgs scenario. The holographic approach allows to describe the qualitative features of the non-perturbative dynamics in the Veneziano limit. We introduce new bottom-up holographic models, which incorporate the backreaction of flavour on the geometry, and show that this can correlate the mass gap to the scale of flavour-symmetry breaking. We compute the mass spectrum for the various composite bosonic states, and study its dependence on the scaling dimension of the symmetry-breaking operators, as well as on the number of flavours. The different regions with a light dilaton are critically surveyed. We carefully assess the domain of validity of the holographic approach, and compare it with lattice simulations and the Nambu-Jona-Lasinio model.


2021 ◽  
Vol 32 (4) ◽  
pp. 641-661
Author(s):  
Klaus Wiegerling

The theory of resistance here elaborated is based on considerations current since the 18th century and concern the proof of reality of the external world. However, what is ignored in the course of these proofs are the social, psychological, and in particular the logical aspects of resistance. The idea of a theory of resistance is inspired by tendencies in the philosophy of technology, as well as other current philosophical and scientific lines of thought that obscure their metaphysical underpinnings, advocating a position of complete achievability of human and natural relations. The theory of resistance seeks to show that resistance is a reflexive term that concerns relations, not objects or those relations that can be expressed in qualities and quantities. Furthermore, this concept has a positioning role, important in epistemological, as well as ethical and anthropological sense. Resistance is a central, although not the sole characteristic of reality. As an ethical category, it is articulated, for example, in the idea of dignity if understood as hostility to mere typologization and subjection to calcu?lation. The theory of resistance does not advocate some existing reality, but limits the domain of validity of constructivist and narrativist theories.


Author(s):  
Christopher Odogwu CHIDI

The study examined the relationship between retention strategies and performance of organisations in the FOBTOB industry. The effect of retention strategies on performance of unionised organisations in the FOBTOB industry was also examined. The survey research design was adopted. A total of 420 research subjects were drawn from fourteen respondent companies using the simple random sampling and proportional stratified sampling techniques. The research instrument was subjected to validity and reliability tests. The domain of validity also called intrinsic validity was used for the validity estimate as well as content validity. The domain of validity was obtained by calculating the square root of reliability. The Cronbach Alpha was used for the reliability test. It was hypothesised that that there is no relationship between retention strategies and performance of unionised organisations in the industry studied. The result of hypothesis test shows that retention strategies are statistically and significantly related with all the measures of performance, such as growth in number of employees (r =0.370; p< 0.01); profitability (r = 0.264; p< 0.01); innovativeness (r = 0.279; p< 0.01); performance stability (r = 0.241; p< 0.01); and rate of sales (r = 0.207; p< 0.01) while the Chisquare test result is (χ2=231.507, df=3, p< 0.01) confirmed the results of the correlation test. It was also hypothesised that retention strategies do not affect performance of unionised organisations in the Industry studied. The results of the regression test revealed that retention strategies affect performance of unionised organisations in the FOBTOB industry. It is recommended that organisations should not rely only on intrinsic variables to influence employee retention; rather, a combination of both intrinsic and extrinsic variables should be considered as an effective retention strategy if optimal performance indices are to be achieved


Author(s):  
Raoul Sommeillier ◽  
Frédéric Robert

Our research studies about student’s prior knowledge acting as learning difficulties (referred to as preconceptions) in electricity courses at university level led us to define knowledge as the association of two elements: a model and a domain of validity (DoV). This statement is the core of the DoV framework. This framework reveals its powerfulness in the way it helps teachers to map students’ cognitive structures, to identify their preconceptions as well as to derive effective teaching strategies. Quantitative experimentations we carry out indicate a lack of global circuit solving strategy among students. Especially, they highlight the fact that the difficulties encountered by those students in network analysis are not that much relying on the mastering of solving methods but on the method selection process. This lack of solving strategy prevents the students to grasp the domain of validity of the solving methods they master, so to associate the relevant methods with the suitable circuits. This paper depicts how the application of the DoV framework to this problem-solving process reveals to be a great tool to identify and tackle students’ (methodological) preconceptions as well as to formalize, rationalize and simplify complex solving strategies making them easier to explain, teach and learn. 


TecnoLógicas ◽  
2019 ◽  
Vol 22 (45) ◽  
pp. 1-7 ◽  
Author(s):  
José José Barba-Ortega ◽  
Jesús D. González ◽  
Miryam Rincón-Joya

The Time-dependent Ginzburg–Landau model (TDGLM) is a robust tool widely used to analyze the magnetization of the single-vortex state of a mesoscopic superconducting sample in presence of a magnetic field. The algorithm implemented in this work is applied to a square geometry surrounded by different kinds of materials simulated by deGennes extrapolation length . The inside of the sample remains at constant temperature , while its boundary remains at temperature . This temperature variation in the sample can be generated by a continuous laser wave injected into all the internal points, except for a thin surface layer in the boundary of the material. We found that the b value at , which mimics the magnetization curve for a corresponding , presents a linear dependence with the temperature. Therefore, although within the domain of validity TDGLM the parameter  is to be considered temperature-independent in the vicinity of the bulk critical temperature and that  depends on the density of states near the surface, we propose a simple dependence of using a TDGLM.


2018 ◽  
Vol 89 (15) ◽  
pp. 3024-3033
Author(s):  
Ludwig Vinches ◽  
Ludovic Tuduri ◽  
Stéphane Hallé

Airborne nanoparticles represent a new danger in occupational health. Numerous theoretical and experimental studies have been conducted on the efficiency of filtering media used for respiratory protection, but few have focused on media used for skin protective equipment. Indeed, a significant proportion of airborne nanoparticles can end up on the skin, causing local effects and eventually penetrating the human body. Following experimental data obtained with sodium chloride nanoparticles, the authors propose an empirical model to evaluate the penetration of airborne nanoparticles through medium used in disposable coveralls. This study presents an adaptation of the conventional filtration theory used for filtering media used in respirators. The authors' model is compared with Wang et al.'s and Brochot's models and demonstrates improvements in their descriptive ability. Moreover, a domain of validity of the proposed model was determined that will enable the evaluation of the efficiency of similar protective apparel material structures against airborne nanoparticles.


2018 ◽  
Vol 27 (05) ◽  
pp. 1830003 ◽  
Author(s):  
Elena Petreska

In this paper, we review recent progress in the description of unpolarized transverse-momentum-dependent (TMD) gluon distributions at small [Formula: see text] in the color glass condensate (CGC) effective theory. We discuss the origin of the nonuniversality of TMD gluon distributions in the TMD factorization framework and in the CGC theory and the equivalence of the two approaches in their overlapping domain of validity. We show some applications of this equivalence, including recent results on the behavior of TMD gluon distributions at small [Formula: see text], and on the study of gluon saturation. We discuss recent advances in the unification of the TMD evolution and the nonlinear small-[Formula: see text] evolution of gluon distributions.


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