2,671 research outputs found
Simulating Turing Machines with Polarizationless P Systems with Active Membranes
We prove that every single-tape deterministic Turing machine working in
t(n)
t(n)
time, for some function
t:N→N
t:N→N
, can be simulated by a uniform family of polarizationless P systems with active membranes. Moreover, this is done without significant slowdown in the working time. Furthermore, if
logt(n)
logt(n)
is space constructible, then the members of the uniform family can be constructed by a family machine that uses
O(logt(n))
O(logt(n))
space.Ministerio de Economía y Competitividad TIN2012-3743
Large characteristically simple sections of finite groups
In this paper we prove that if G is a group for which there are k non-Frattini chief factors isomorphic to a characteristically simple group A, then G has a normal section C/R that is the direct product of k minimal normal subgroups of G/R isomorphic to A. This is a significant extension of the notion of crown for isomorphic chief factors
Bounds on the number of maximal subgroups of finite groups: applications
The determination of bounds for the number of maximal subgroups of a given index in a finite group is relevant to estimate the number of random elements needed to generate a group with a given probability. In this paper, we obtain new bounds for the number of maximal subgroups of a given index in a finite group and we pin-point the universal constants that appear in some results in the literature related to the number of maximal subgroups of a finite group with a given index. This allows us to compare properly our bounds with some of the known bounds
Los procesos formativos en el desarrollo de competencias del técnico superior universitario, bajo un modelo de educación humanista. un estudio de caso
Esta tesis es sobre los procesos formativos en el Técnico Superior Universitario (TSU). Se trata de una investigación cualitativa inmersa en un marco interpretativo con enfoque fenomenológico - fenomenográfico, que intenta comprender cómo son los procesos formativos en la trayectoria universitaria de los estudiantes de las carreras de corta duración, bajo un modelo de educación humanista. Se trata de una investigación que recupera la voz de tres principales actores: profesores, estudiantes y empleadores, sobre las experiencias vividas en torno a los procesos de enseñanza y aprendizaje.ITESO, A. C
Towards defining the role of glycans as hardware in information storage and transfer: Basic principles, experimental approaches and recent progress
The term `code' in biological information transfer appears to be tightly and hitherto exclusively connected with the genetic code based on nucleotides and translated into functional activities via proteins. However, the recent appreciation of the enormous coding capacity of oligosaccharide chains of natural glycoconjugates has spurred to give heed to a new concept: versatile glycan assembly by the genetically encoded glycosyltransferases endows cells with a probably not yet fully catalogued array of meaningful messages. Enciphered by sugar receptors such as endogenous lectins the information of code words established by a series of covalently linked monosaccharides as fetters for example guides correct intra- and intercellular routing of glycoproteins, modulates cell proliferation or migration and mediates cell adhesion. Evidently, the elucidation of the structural frameworks and the recognition strategies within the operation of the sugar code poses a fascinating conundrum. The far-reaching impact of this recognition mode on the level of cells, tissues and organs has fueled vigorous investigations to probe the subtleties of protein-carbohydrate interactions. This review presents information on the necessarily concerted approach using X-ray crystallography, molecular modeling, nuclear magnetic resonance spectroscopy, thermodynamic analysis and engineered ligands and receptors. This part of the treatise is flanked by exemplarily chosen insights made possible by these techniques. Copyright (C) 2001 S. Karger AG, Basel
La seca de encinas y alcornoques en Andalucía : decaimiento y enfermedad
El decaimiento forestal es una enfermedad de
etiología compleja, resultado de la acción de un
número variable de factores bióticos y abióticos que
causan un deterioro gradual y general de los árboles
afectados, hasta su muerte. Los factores implicados en
el decaimiento de los Quercus en Andalucía son
factores predisponentes de tipo selvícola, alteraciones
climáticas como factor incitante, y plagas y
enfermedades como factores contribuyentes. Entre las
enfermedades implicadas en Seca de los Quercus
destacan, por orden de importancia, la podredumbre
radical causada por Phytophthora cinnamomi, los
chancros de tronco y ramas causados por
Botryosphaeria spp. y el chancro carbonoso causado
por Biscogniauxia mediterranea. No obstante, las dos
primeras enfermedades tienen una especial incidencia
en distintas zonas de Andalucía de forma
independiente, no asociadas al decaimiento. En el
presente artículo se exponen las medidas de control
disponibles contra estas enfermedades de los Quercus
y se plantea la necesidad de disponer de un
diagnóstico preciso en cada caso para abordar dicho
control con garantías, ya que no cabe encontrar
soluciones únicas que resulten eficaces con
independencia de la naturaleza del problema._____________________________________The forestry decline is a complex disease, as a result
of the action of a changeable number of biotic and
abiotic factors that cause a gradual and general
deterioration of the affected trees, until their death.
The factors involved in the Quercus decline in
Andalusia are predisposing factors like silvic,
climatic alterations as inciting factor, and insect pest
and diseases as contributing factors. Between the
diseases involved in oak decline stand out, in order
of importance, the root roting caused by
Phytophthora cinnamomi, the chancres of trunk and
branches caused by Botryosphaeria spp. and the
charcoal canker caused by Biscogniauxia
mediterranea. Nevertheless, the first two diseases
have a special effect on different zones of Andalusia
in different ways, not associated with the decay. In
this article we expose the available tools of disease
control. We emphasizes the need of having a precise
diagnosis in every case to approach the control with
guarantees, since there is no chance of finding only
one efficient solution regardless of the nature of the
problem
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Additive Manufacturing with RepRap Methodology: Current Situation and Future Prospects
In February 2004, Adrian Bowyer, from the University of Bath, began an open initiative
called RepRap, with the purpose of creating an open source rapid prototyping machine
which, moreover, could replicate itself. This article analyzes the current status of the
RepRap initiative, commenting the basic components of RepRap machines, the
differences between the different 3D printers developed by the RepRap community so
far, and the technical possibilities that opens this technology from the engineering point
of view. In addition we propose some improvements that could be perfectly feasible in
the short term. For this purpose, the assembly of a RepRap Mendel Prusa was
performed, but with some modifications.Mechanical Engineerin
Decision P Systems and the P =NP Conjecture
We introduce decision P systems, which are a class of P
systems with symbol-objects and external output. The main result of
the paper is the following: if there exists an NP–complete problem that
cannot be solved in polynomial time, with respect to the input length, by
a deterministic decision P system constructed in polynomial time, then
P = NP. From Zandron-Ferreti-Mauri’s theorem it follows that if P =
NP, then no NP–complete problem can be solved in polynomial time,
with respect to the input length, by a deterministic P system with active
membranes but without membrane division, constructed in polynomial
time from the input. Together, these results give a characterization of
P = NP in terms of deterministic P systems
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