Search results for "REPRESENTATION"
showing 10 items of 1710 documents
Transmission of Genetic Properties in Permutation Problems: Study of Lehmer Code and Inversion Table Encoding
2021
Solution encoding describes the way decision variables are represented. In the case of permutation problems, the classical encoding should ensure that there are no duplicates. During crossover operations, repairs may be carried out to correct or avoid repetitions. The use of indirect encoding aims to define bijections between the classical permutation and a different representation of the decision variables. These encodings are not sensitive to duplicates. However, they lead to a loss of genetic properties during crossbreeding. This paper proposes a study of the impact of this loss both in the space of decision variables and in that of fitness values. We consider two indirect encoding: the …
Visión de los maestros en formación sobre los modelos científicos y sus funciones en las ciencias y en su enseñanza
2017
Este estudio examina la visión de 201 futuros maestros sobre los modelos científicos y sus funciones en ciencias y en su enseñanza. Se diseñó e implementó un cuestionario con cinco preguntas abiertas, de las cuales se analizan dos ¿Qué se entiende por modelo científico? y ¿Para qué consideras que son utilizados los modelos en ciencias? ¿Y en la enseñanza de las ciencias? Los resultados mostraron que, aunque un 24,5% reconocen que un modelo científico es una representación simplificada de un fenómeno, encontramos que un 22,8% lo consideran como “método” de trabajo de los científicos En cuanto a sus funciones, un 45,7% identifican los modelos como recursos para explicar, resumir o ejemplifica…
Whence pseudoscience? An epidemiological approach
2017
In this paper, we develop an epidemiological approach to account for the typical features and persistent popularity of pseudoscience. An epidemiology of pseudoscience aims at explaining why some beliefs become widely distributed whereas others do not and hence seeks to identify the factors that exert a causal effect on this distribution. We pinpoint and discuss several factors that promote the dissemination of pseudoscientific beliefs. In particular, we argue that such beliefs manage to spread widely because they are intuitively appealing, manage to hitchhike on the authority of science, and successfully immunize themselves from criticism.
“Ni la presencia ni la ausencia”: el concepto de representación y sus implicaciones
2015
El presente trabajo plantea un análisis histórico-filosófico del ambivalente concepto de representación política. Partiendo de la concepción tradicional según la cual puede definirse la representación como la presencia de una ausencia, desgranaremos las diferentes visiones de este concepto que han propuesto las diversas tradiciones políticas –la democrática, la liberal y la revolucionaria– así como las implicaciones en varios órdenes que arrastra cada una.http://dx.doi.org/10.15304/ag.35.1.2260
Differential gene expression in p53-mediated G(1) arrest of human fibroblasts after gamma-irradiation or N-phosphoacetyl-L-aspartate treatment.
2000
In human fibroblasts, N:-phosphoacetyl-L-aspartate (PALA) and gamma-radiation induce reversible and irreversible p53-mediated G(1) cell cycle arrest, respectively. By coupling the premature chromosome condensation technique to fluorescence in situ hybridization, we found no evidence of DNA damage after PALA treatment. We used representational difference analysis (cDNA-RDA) to study changes in gene expression after PALA treatment and gamma-radiation in normal human fibroblasts. The mammary-derived growth inhibitor (MDGI) gene was expressed in PALA-treated cells. Ectopic MDGI expression arrested PALA-treated but not irradiated RKO cells. Expression of an antisense RNA against MDGI resulted in…
An operator-like description of love affairs
2010
We adopt the so--called \emph{occupation number representation}, originally used in quantum mechanics and recently considered in the description of stock markets, in the analysis of the dynamics of love relations. We start with a simple model, involving two actors (Alice and Bob): in the linear case we obtain periodic dynamics, whereas in the nonlinear regime either periodic or quasiperiodic solutions are found. Then we extend the model to a love triangle involving Alice, Bob and a third actress, Carla. Interesting features appear, and in particular we find analytical conditions for the linear model of love triangle to have periodic or quasiperiodic solutions. Numerical solutions are exhibi…
Lorentzian-geometry-based analysis of airplane boarding policies highlights "slow passengers first" as better.
2019
We study airplane boarding in the limit of large number of passengers using geometric optics in a Lorentzian metric. The airplane boarding problem is naturally embedded in a 1+1 dimensional space-time with a flat Lorentzian metric. The duration of the boarding process can be calculated based on a representation of the one-dimensional queue of passengers attempting to reach their seats, into a two-dimensional space-time diagram. The ability of a passenger to delay other passengers depends on their queue positions and row designations. This is equivalent to the causal relationship between two events in space-time, whereas two passengers are time-like separated if one is blocking the other, an…
P -wave nucleon-pion scattering amplitude in the Δ(1232) channel from lattice QCD
2021
We determine the $\mathrm{\ensuremath{\Delta}}(1232)$ resonance parameters using lattice QCD and the L\"uscher method. The resonance occurs in elastic pion-nucleon scattering with ${J}^{P}=3/{2}^{+}$ in the isospin $I=3/2$, $P$-wave channel. Our calculation is performed with ${N}_{f}=2+1$ flavors of clover fermions on a lattice with $L\ensuremath{\approx}2.8\text{ }\text{ }\mathrm{fm}$. The pion and nucleon masses are ${m}_{\ensuremath{\pi}}=255.4(1.6)\text{ }\text{ }\mathrm{MeV}$ and ${m}_{N}=1073(5)\text{ }\text{ }\mathrm{MeV}$, respectively, and the strong decay channel $\mathrm{\ensuremath{\Delta}}\ensuremath{\rightarrow}\ensuremath{\pi}N$ is found to be above the threshold. To thorough…
Numerical integration of subtraction terms
2016
Numerical approaches to higher-order calculations often employ subtraction terms, both for the real emission and the virtual corrections. These subtraction terms have to be added back. In this paper we show that at NLO the real subtraction terms, the virtual subtraction terms, the integral representations of the field renormalisation constants and -- in the case of initial-state partons -- the integral representation for the collinear counterterm can be grouped together to give finite integrals, which can be evaluated numerically. This is useful for an extension towards NNLO.
Implications of tau data for CP violation in K decays
2019
The \bm{D=6}𝐃=6 contribution of the Operator Product Expansion (OPE) of the \bm{\mathrm{VV-AA}}VV−AA correlator of quark currents can be related to hadronic matrix elements associated to CP violation in non-leptonic kaon decays. We use those relations to find an updated value for \bm{\langle(\pi\pi)_{I=2}|\mathcal{Q}_{8}|K\rangle}⟨(𝛑𝛑)𝐈=2|𝒬8|𝐊⟩ in the chiral limit using the updated ALEPH spectral function. Taking instead values of the matrix elements from the lattice to obtain the \bm{D=6}𝐃=6 vacuum elements provides a new short-distance constraint that allows for an inclusive determination of \bm{f_{\pi}}𝐟𝛑 and an updated value for the \bm{D=8}𝐃=8 condensate.