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Search Results: 1 - 10 of 564 matches for " Kogan-Cogan "
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Jóvenes contemporáneos: entre el trabajo emocional y estético en el mundo corporativo
Liuba, Kogan-Cogan
Boletín Científico Sapiens Research , 2012,
Abstract: In this research we examine the contemporary sociocultural context and its relationship with the corporal image that young women and males, students of the management and economic areas of a private university in Lima, consider “ideal”. Specifically, we focus on the type of corporal management that students consider to be important to help them gain access to the corporate environment in order to develop a successful career. That is, we want to know the meaning that young people who will form part of the political and economic elites of the country give to the relation between their bodies, super egos and their sociocultural environment. The results of this study are a product of two methodolog-ical approaches: the Q multivariable analysis allowed us to identify those factors that students of both sexes regarded to be important to manage their bodies as social capital. Then, we performed qualitative analysis of the information obtained in focus groups.
RKKY Interaction in Gapped or Doped Graphene  [PDF]
Eugene Kogan
Graphene (Graphene) , 2013, DOI: 10.4236/graphene.2013.21002
Abstract: In our previous work [1] we calculated RKKY interaction between two magnetic impurities in pristine graphene using the Green’s functions (GF) in the coordinate-imaginary time representation. Now we show that the calculations of the GF in this representation can be simplified by using the Feynman’s trick, which allows to easily calculate RKKY interaction in gapped graphene. We also present calculations of the RKKY interaction in gapped or doped graphene using the coordinate-imaginary frequency representation. Both representations, corresponding to calculation of the bubble diagram in Euclidean space, have an important advantage over those corresponding to calculation in Minkowskii space, which are very briefly reviewed in the Appendix to the present work. The former, in distinction to the latter, operate only with the convergent integrals from the start to the end of the calculation.
Symmetry Classification of Energy Bands in Graphene and Silicene  [PDF]
Eugene Kogan
Graphene (Graphene) , 2013, DOI: 10.4236/graphene.2013.22011
Abstract: We present the results of the symmetry classification of the electron energy bands in graphene and silicene using group theory algebra and the tight-binding approximation. The analysis is performed both in the absence and in the presence of the spin-orbit coupling. We also discuss the bands merging in the Brillouin zone symmetry points and the conditions for the latter to become Dirac points.
Lattice Operators and Topologies
Eva Cogan
International Journal of Mathematics and Mathematical Sciences , 2009, DOI: 10.1155/2009/474356
Abstract: Working within a complete (not necessarily atomic) Boolean algebra, we use a sublattice to define a topology on that algebra. Our operators generalize complement on a lattice which in turn abstracts the set theoretic operator. Less restricted than those of Banaschewski and Samuel, the operators exhibit some surprising behaviors. We consider properties of such lattices and their interrelations. Many of these properties are abstractions and generalizations of topological spaces. The approach is similar to that of Bachman and Cohen. It is in the spirit of Alexandroff, Frolík, and Nöbeling, although the setting is more general. Proceeding in this manner, we can handle diverse topological theorems systematically before specializing to get as corollaries as the topological results of Alexandroff, Alo and Shapiro, Dykes, Frolík, and Ramsay.
Um modelo de reconcilia??o de dados para o custeio baseado-em-atividades (ABC)
Cogan, Samuel;
Revista de Administra??o de Empresas , 1999, DOI: 10.1590/S0034-75901999000200006
Abstract: cost structure changes, due to new production technologies, to major diversification needed because of business competitivity, and to cost reduction, have motivated the development programmes of new cost management techniques that allocate indirect costs to each product more precisely. in this context, activity-based costing/activity- based management (abc/abm) is considered as one of the most important techniques that have emerged in the last few years to provide accurate estimates for indirect expenses that each product consumes. nevertheless, some difficulties to obtain some costs remain, even when using abc. this happens not only due to the impossibility to measure costs with adequate accuracy, but also due to the fact that the investments made to measure some costs exceed the benefits to be obtained. in order to address this problem, the present work provides a business cost flow framework utilizing data reconciliation used in chemical process networks to determine indirect costs, incorporating accurate information concerning some of the costs. the model developed utilizes non-linear programming.
Samuel Cogan
Revista Universo Contábil , 2007,
Abstract: The Theory of Constraints (TOC) and Activity-based Costing (ABC), although opposite in their basic foundations, can concur in integration studies which attempt to show that these methods applied together perform better when compared to their individual use. As for that integration, a group of authors (CAMPBELL,1992; MAcARTHUR, 1993; HOLMEN, 1995; FRITZSCH, 1997) defends an idea of the difference between these two methodologies being a matter of the time horizon: TOC used in the short term and ABC in the long term. The present article’s objective is to show, through a numeric illustration, considerations of that group of studies. Therefore, the TOC decision making is compared with other costing methods: Absorption Costing, Activity-based Costing and Variable Costing. The data analysis permits to confirm that TOC has produced a better result than the other techniques, in the short term. In the long term, however, when idle capacities can be exploited fully in the absence of internal constraints, ABC proved to be the technique that leads to the best result. Keywords: Integration. Theory of Constraints. Activity-based Costing. A Teoria das Restri es (TOC) e o Custeio Baseado em Atividades (ABC), embora opostos em seus fundamentos básicos, podem se conciliar em estudos de integra o que buscam mostrar que juntos s o superiores à sua abordagem individual. No que se refere a essa integra o, um grupo de autores (CAMPBELL,1992; MAcARTHUR, 1993; HOLMEN, 1995; FRITZSCH, 1997) defende que a diferen a entre essas duas metodologias é uma quest o de horizonte de tempo: a Teoria das Restri es para o curto prazo e o Custeio Baseado em Atividades para o longo prazo. O presente artigo tem por objetivo mostrar, através de uma ilustra o numérica, as considera es desse grupo de estudos. Para tanto, a tomada de decis o da Teoria das Restri es é comparada com outros métodos de custeio: Custeio por Absor o Tradicional, Custeio Baseado em Atividades e o Custeio Variável. A análise dos dados obtidos permite confirmar que a Teoria das Restri es apresentou resultado melhor que as demais técnicas no curto prazo. No longo prazo, contudo, em que as capacidades n o usadas podem ser utilizadas em sua plenitude, n o existindo, pois, restri es internas, o Custeio Baseado em Atividades mostrou ser a técnica que conduz ao melhor resultado. Palavras-chave: Integra o. Teoria das Restri es. Custeio Baseado em Atividades.
Opening of a Gap in Graphene Due to Supercell Potential: Group Theory Point of View  [PDF]
E. Kogan, M. Kaveh
Graphene (Graphene) , 2014, DOI: 10.4236/graphene.2014.32004

We analyze in the framework of the space group theory the change of the dispersion law in grapenein and the vicinity of the (former) Dirac points due to application of supercell potential with the \"\" space priodicity and the same point symmetry as graphene.

On the X-Ray Edge Problem in Graphene  [PDF]
Eugene Kogan, Moshe Kaveh
Graphene (Graphene) , 2018, DOI: 10.4236/graphene.2018.71001
We calculate the core-hole spectral density in a pristine graphene, where the density of states of itinerant electrons goes linearly to zero at the Fermi level. We consider explicitly two models of electron-hole interaction. In the unscreened Coulomb interaction model, the spectral density is similar to that in metal (for local interaction). Thus there is no δ-function singularity in the core-hole spectral density. In the local interaction model, the δ-function singularity survives, but the interaction leads to the appearance of the background in the spectral density.
Failure of antibiotic treatment in microbial populations
Patrick De Leenheer,Nick Cogan
Quantitative Biology , 2008,
Abstract: The tolerance of bacterial populations to biocidal or antibiotic treatment has been well documented in both biofilm and planktonic settings. However, there is still very little known about the mechanisms that produce this tolerance. Evidence that small, non-mutant subpopulations of bacteria are not affected by antibiotic challenge has been accumulating and provides an attractive explanation for the failure of typical dosing protocols. Although a dosing challenge can kill all the susceptible bacteria, the remaining persister cells can serve as a source of population regrowth. We give a robust condition for the failure of a periodic dosing protocol for a general chemostat model, which supports the mathematical conclusions and simulations of an earlier, more specialized batch model. Our condition implies that the treatment protocol fails globally, in the sense that a mixed bacterial population will ultimately persist above a level that is independent of the initial composition of the population. We also give a sufficient condition for treatment success, at least for initial population compositions near the steady state of interest, corresponding to bacterial washout. Finally, we investigate how the speed at which the bacteria are wiped out depends on the duration of administration of the antibiotic. We find that this dependence is not necessarily monotone, implying that optimal dosing does not necessarily correspond to continuous administration of the antibiotic. Thus, genuine periodic protocols can be more advantageous in treating a wide variety of bacterial infections.
Asymptotic expansions for large closed and loss queueing networks
Yaakov Kogan
Mathematical Problems in Engineering , 2002, DOI: 10.1080/10241230306726
Abstract: Loss and closed queueing network models have long been of interest to telephone and computer engineers and becoming increasingly important as models of data transmission networks. This paper describes a uniform approach that has been developed during the last decade for asymptotic analysis of large capacity networks with product form of the stationary probability distribution. Such a distribution has an explicit form up to the normalization constant, or the partition function. The approach is based on representing the partition function as a contour integral in complex space and evaluating the integral using the saddle point method and theory of residues. This paper provides an introduction to the area and a review of recent work.
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