16,017 research outputs found
ELEMENTS INVOLVED IN THE TERRITORY BRAND FROM RESIDENTS’ PERCEPTION: THE CITY OF MÁLAGA
The brand might create a position of the territory that could be useful for the development of geographical spaces. It could also become a solid basis upon which to make decisions about the tourism planning of a city. This paper deals with the features, which are recognized by residents as those that are involved in the creation of Málaga brand.
In order to achieve the goals set in this research, a descriptive methodology has been used. This study has been carried out using a questionnaire in which 1230 residents have participated. The findings have corroborated the hypotheses. Indeed, the results show that Málaga brand is being built under the concept of culture and that some places of the city are vital in the making of the territory image. This also encourages economic growth and hence employment. This paper offers important implications and tools to both public and private institutions insofar as they promote tourism promotion campaigns
Changing Times at Cuban Universities: Looking into the Transition towards a Social, Entrepreneurial and Innovative Organization
Since the 1990s, the socialist higher education system has faced several reforms oriented to satisfy the social, economic, and technological demands. However, little is known about the transformation process of the socialist university system over the past two decades. This study provides a better understanding of the entrepreneurial and innovative transition of universities located in socialist economies. By adopting mixed theoretical approaches, we proposed a conceptual model to understand the social, the innovative and the entrepreneurial transformation of socialist universities. We revised/tested this model in the context of the Cuban University by implementing a prospective case study approach. Our findings show insights about the transition towards a business model innovation within the Cuban university. The determinants have been the state regulations, the closing of the complete cycle from teaching to the commercialization of results and the creation of hybrid structures to manage knowledge. Consequently, the university is facing managerial challenges related to its ability to explore/exploit its activities to generate social, innovative and economic outcomes. Our results provide practical implications for the university managers and actors involved in the transformation process of the Cuban Universit
Portfolio modeling for an algorithmic trading based on control theory
In the present paper, a mathematical model for a portfolio is proposed. This model is valid for operations of buying and selling shares of an asset in constant periods of time, additionally, it has a states space form which can be used to design a control law using control theory. The control law designed can be interpreted as a trading signal to reach a portfolio value desired. The mathematical model and control law proposed are validated by means simulations using real daily prices of Mexican stock exchange
Nuevos mecanismos reguladores de las neuronas Kiss1 durante el desarrollo del eje reproductor y en condiciones de estrés metabólico: Análisis del papel de los microRNAs y los elementos de control de la secreción
Reproduction is indispensable for the perpetuation of the species. Therefore, it is safeguarded by a sophisticated network of regulatory mechanisms that ultimately controls the reproductive function by modulating the activity of the so-called hypothalamicpituitary- gonadal (HPG) axis1,2. The HPG axis is composed by: i) the hypothalamus, where a scattered and small population of neurons secreting the gonadotropin-releasing hormone (GnRH) resides; ii) the anterior pituitary, where GnRH stimulates gonadotroph cells to secrete gonadotropin hormones, luteinizing hormone (LH) and folliclestimulating hormone (FSH); and iii) the gonads, testes in males and ovaries in females, where gonadotropins stimulate both gametogenesis and the secretion of peptide and steroid hormones. Importantly, GnRH neurons constitute the main hierarchical element where all regulatory signals ultimately converge for the brain control of reproduction1. In this context, the Kiss1/Gpr54 system, composed by kisspeptins and their receptor, Gpr54, has emerged as the most important upstream regulator of GnRH neurons, with an essential role for the acquisition (puberty) and the maintenance (fertility) of the reproductive function3. Thus, the roles of Kiss1 neurons, controlling both the surge and pulsatile modes of GnRH/gonadotropin secretion, have been well characterized4. Given their importance, substantial efforts have been made in the field to understand the regulatory mechanism controlling Kiss1 neurons3,5. However, considering that most on the attention has been focused on studying the transcriptional regulation of Kiss1 expression, our knowledge about other mechanisms potentially contributing to the regulation of Kiss1 neurons is still fragmentary and yet to be fully disclosed.
In this context, microRNAs (miRNAs) are small RNA molecules that act as epigenetic regulators by post-transcriptionally repressing gene expression6. Albeit other epigenetic mechanisms regulating the Kiss1 gene, such as DNA methylation and histone modifications, have begun recently to be explored5,7, the role of miRNAs in the control of Kiss1 neurons has remain elusive until now. In the same vein, previous evidence in the literature evaluating changes in both Kiss1 mRNA and kisspeptin protein in response to certain experimental conditions hinted that these two parameters do not always change in the same manner8–10, suggesting the existence of an additional mechanism of regulation of Kiss1 neurons at the secretory level. However, despite its potential relevance, the functional characterization and the molecular basis of this regulatory mechanism controlling the secretory capacity of Kiss1 neurons had not been explored so far.
On this basis, this Doctoral Thesis has explored: (i) the physiological role and molecular mechanisms of miRNAs in Kiss1 neurons for the control of reproductive function; and (ii) the main elements of the secretory pathway operating in Kiss1 neurons that participates in the adaptative responses to a condition of metabolic stress.La reproduccion es una funcion indispensable para la perpetuacion de las especies. Por tanto, se encuentra bajo el control de una sofisticada red de mecanismos reguladores que en ultima instancia controlan su funcionamiento a traves de la modulacion de la actividad del llamado eje hipotalamo-hipofiso-gonadal (HHG)1,2. El eje HHG esta compuesto por: i) el hipotalamo, donde reside una pequena y dispersa poblacion de neuronas que secretan la hormona liberadora de gonadotropinas (GnRH); ii) la adenohipofisis, donde la GnRH estimula a las celulas gonadotropas para que secreten gonadotropinas, las cuales son la hormona luteinizante (LH) y la hormona foliculo-estimulante (FSH); y iii) las gonadas, testiculos en machos y ovarios en hembra, donde las gonadotropinas estimulan tanto la gametogenesis como la secrecion de hormonas de naturaleza peptidica y esteroidea. En este sentido, las neuronas GnRH constituyen un elemento jerarquico clave en el que convergen en ultima instancia todas las senales que participan en el control de la reproduccion a nivel central1. En este contexto, el sistema Kiss1/Gpr54, compuesto por las kisspeptinas y su receptor, Gpr54, ha sido reconocido en las ultimas decadas como uno de los reguladores mas importantes de las neuronas GnRH, teniendo un papel fundamental para la adquisicion (pubertad) y el mantenimiento (fertilidad) de la función reproductora3. De hecho, se ha caracterizado el importante papel de las neuronas Kiss1 en el control de la secrecion pulsatil y el pico preovulatorio de GnRH/gonadotropinas4.
Dada su importancia, se han llevado a cabo esfuerzos sustanciales en el campo para comprender los mecanismos reguladores que controlan a las neuronas Kiss13,5. Sin embargo, dado que la mayoria de la atencion se ha centrado en el estudio de los mecanismos de regulacion transcripcional que controlan la expresion del gen Kiss1, nuestro conocimiento sobre otros mecanismos que puedan contribuir de forma potencial a la regulacion de las neuronas Kiss1 es aun limitado y necesita ser ampliado.
En este contexto, los microRNAs (miRNAs) son pequenas moleculas de RNA que actúan como reguladores epigeneticos mediante la represion post-transcripcional de la expresión genica6. Aunque recientemente se han empezado a explorar otros mecanismos epigeneticos que regulan el gen Kiss1, como la metilacion del ADN y las modificaciones de histonas, el papel de los miRNAs5,7 en las neuronas Kiss1 no ha sido explorado hasta la fecha. En la misma linea, existen datos publicados en la literatura que evaluan cambios tanto en los niveles de mRNA de Kiss1 como de la proteina kisspeptina en respuesta a ciertas condiciones experimentales e indican que estos parametros no siempre cambian simultaneamente en la misma direccion8–10, sugiriendo la existencia de un mecanismo de regulacion adicional de las neuronas Kiss1 a nivel secretor. Sin embargo, pese a su potencial relevancia, aun no se han estudiado, hasta la fecha, las características funcionales ni las bases moleculares de este mecanismo de regulacion que controla la capacidad secretora de las neuronas Kiss1.
En este contexto, esta tesis doctoral ha explorado: (i) el papel fisiologico y los mecanismos moleculares a traves de los cuales participan los miRNAs en las neuronas Kiss1 en el control de la funcion reproductora; y (ii) los principales mecanismos de regulacion de la secrecion que operan en neuronas Kiss1 y que participan en las respuestas adaptativas frente a una condicion de estres metabolico
A 10-way power divider based on a transducer and a radial junction operating in the circular TM01 mode
This work presents a 10-way Ku-band power divider using a mode transducer and a radial junction connected by an overmoded circular waveguide operating in the TM 01 mode. The circular symmetry of this mode has been exploited to obtain a power divider with the rectangular output ports radially distributed along the broad wall of the waveguides in H-plane configuration. This topology provides the same amplitude and phase for all the output ports. At the same time, a compact profile has been obtained, introducing a simple manufacturing for the two components of the divider. The first component is a mode transducer converting the TE 10 mode in the rectangular waveguide to the TM 01 mode in the circular waveguide. It is based on a novel topology providing a very high purity in the mode conversion with an attenuation for the other propagating mode, the TE 11c , higher than 60 dB. The second component is a 10-way radial junction that must work under the excitation of the TM 01 , whose special features, since this mode is not the fundamental one of the circular waveguide, will be highlighted. The final design has been validated with an experimental prototype, proposing a manufacturing based on four simple parts. This has been the key to obtain an experimental prototype with specifications in the state-of-the-art. The measured efficiency is better than 96.5% in a 16.7% relative frequency bandwidth from 11 GHz to 13 GHz, with return losses better than 25 dB in the common port. The measured difference between the signals at the output ports of the prototype is ±0.3 dB for the amplitudes and ±0.45° for the phases. A comparison of the obtained results with another divider based on the TE 01 mode shows the potential of the presented design for becoming an alternative to the more extended TE 01 -based power dividersThis work was supported by the Spanish Government through the Agencia Estatal de Investigacion, Fondo Europeo de Desarrollo Regional
(AEI/FEDER, UE), under Grant TEC2016-76070-C3-1/2-R (ADDMATE
Infinite Factorial Finite State Machine for Blind Multiuser Channel Estimation
New communication standards need to deal with machine-to-machine
communications, in which users may start or stop transmitting at any time in an
asynchronous manner. Thus, the number of users is an unknown and time-varying
parameter that needs to be accurately estimated in order to properly recover
the symbols transmitted by all users in the system. In this paper, we address
the problem of joint channel parameter and data estimation in a multiuser
communication channel in which the number of transmitters is not known. For
that purpose, we develop the infinite factorial finite state machine model, a
Bayesian nonparametric model based on the Markov Indian buffet that allows for
an unbounded number of transmitters with arbitrary channel length. We propose
an inference algorithm that makes use of slice sampling and particle Gibbs with
ancestor sampling. Our approach is fully blind as it does not require a prior
channel estimation step, prior knowledge of the number of transmitters, or any
signaling information. Our experimental results, loosely based on the LTE
random access channel, show that the proposed approach can effectively recover
the data-generating process for a wide range of scenarios, with varying number
of transmitters, number of receivers, constellation order, channel length, and
signal-to-noise ratio.Comment: 15 pages, 15 figure
Las hipótesis de Fisher en Latinoamérica: un análisis de cointegración
En este artículo se evalúan las hipótesis de Fisher y de integración de los mercados latinoamericanos mediante pruebas de cointegración y de cambio estructural endógeno. Los hallazgos sugieren varias conclusiones: a) el efecto Fisher se valida principalmente en Costa Rica; b) el efecto internacional de Fisher se valida débilmente entre Chile y Costa Rica y entre Colombia y México; c) la integración de los países y mercados es heterogénea, y d) únicamente Chile no tuvo cambios estructurales. En el estudio se usan series mensuales de Brasil, Chile, Colombia, Costa Rica, México y Perú durante el periodo comprendido entre enero de 1997 y diciembre de 2014.Neste artigo, avaliam-se as hipóteses de Fisher e de integração dos mercados latino-americanos mediante testes de cointegração e de mudança estrutural endógena. Os achados sugerem várias conclusões: a) o efeito Fisher é validado principalmente na Costa Rica; b) o efeito internacional de Fisher é validado debilmente entre o Chile e a Costa Rica, e entre a Colômbia e o México; c) a integração dos países e mercados é heterogênea; d) unicamente o Chile não teve mudanças estruturais. Além disso, usam-se séries mensais do Brasil, Chile, Colômbia, Costa Rica, México e do Peru durante o período compreendido entre janeiro de 1997 e dezembro de 2014.This article evaluates the Fisher hypothesis and the hypothesis of the integration of Latin American markets through co-integration and endogenous structural change tests. The findings suggest a number of conclusions: a) the Fisher effect is validated mainly in Costa Rica; b) the international Fisher effect is validated weakly between Chile and Costa Rica and between Colombia and Mexico; c) the integration of counties and markets is heterogeneous, and d) only Chile did not present structural changes. The study uses monthly series for Brazil, Chile, Colombia, Costa Rica, Mexico and Peru during the January 1997 to December 2014 period
Una década de turismo sin fronteras. El caso de la Región Duero/Douro, el turismo fluvial y la diversidad turística
The membership of Spain and Portugal to the European Union has encouraged cross-border cooperation, promoting the diversification of the tourism in both sides of the Luso-Spanish border. Our analysis takes as a reference Duero/Douro region and the Douro River, this fluvial tourism has revalued cultural, wine and heritage tourism with water activities and cruises, reinforcing the existing tourist diversity. The resource management has allowed on both sides of the border, strengthen the tourism sector linked to the Douro and the Douro, intensifying in the last five years the fluvial activity, gathered around the wine tourism and the natural spaces.La incorporación de España y Portugal a la Comunidad Europea ha impulsado la cooperación transfronteriza y el turismo a ambos lados de la frontera luso española. Nuestro análisis se ciñe a la Región Duero/Douro con el río Duero y el turismo fluvial de referente, un nicho de mercado que ha progresado en los últimos años, revalorizando la diversidad turística existente a través de las actividades acuáticas y el turismo de cruceros. Los recursos y una naturaleza protegida han permitido a ambos lados de la frontera, afianzar el sector turístico ligado al Duero y al Douro, intensificándose en el último lustro la actividad fluvial, reunida al turismo enológico y a los espacios naturales protegidos
Hardy Uncertainty Principle and unique continuation properties of covariant Schrodinger flows
We prove a logarithmic convexity result for exponentially weighted
-norms of solutions to electromagnetic Schr\"odinger equation, without
needing to assume smallness of the magnetic potential. As a consequence, we can
prove a unique continuation result in the style of the Hardy uncertainty
principle, which generalizes the analogous theorems which have been recently
proved by Escauriaza, Kenig, Ponce and Vega.Comment: 26 page
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