30 research outputs found
NMDA Receptor Modulators in the Treatment of Drug Addiction
Get PDFGlutamate plays a pivotal role in drug addiction, and the N-methyl-D-aspartate (NMDA) glutamate receptor subtype serves as a molecular target for several drugs of abuse. In this review, we will provide an overview of NMDA receptor structure and function, followed by a review of the mechanism of action, clinical efficacy, and side effect profile of NMDA receptor ligands that are currently in use or being explored for the treatment of drug addiction. These ligands include the NMDA receptor modulators memantine and acamprosate, as well as the partial NMDA agonist D-cycloserine. Data collected to date suggest that direct NMDA receptor modulators have relatively limited efficacy in the treatment of drug addiction, and that partial agonism of NMDA receptors may have some efficacy with regards to extinction learning during cue exposure therapy. However, the lack of consistency in results to date clearly indicates that additional studies are needed, as are studies examining novel ligands with indirect mechanisms for altering NMDA receptor function
Dynamics of High-Technology Firms in the Silicon Valley
Get PDFThe pace of technological innovation since World War II is dramatically accelerating following the commercial exploitation of the Internet. Since the mid 90’s fiber optics capacity (infrastructure for transmission of information including voice and data) has incremented over one hundred times thanks to a new technology, dense wave division multiplexing, and Internet traffic has increased over 1.000 times. The dramatic advances in information technology provide excellent examples of the critical relevance of the knowledge in the development of competitive advantages. The Silicon Valley (SV) that about fifty years ago was an agricultural region became the center of dramatic technological and organizational transformations. In fact, most of the present high-tech companies did not exist twenty years ago. Venture capital contribution to the local economy is quite important not only due to the magnitude of the financial investment (venture investment in SV during 2000 surpassed 25.000 millions of dollars) but also because the extent and quality of networks (management teams, senior employees, customers, providers, etc.) that bring to emerging companies. How do new technologies develop? What is the role of private and public investment in the financing of R&D? Which are the most dynamical agents and how do they interact? How are new companies created and how do they evolve? The discussion of these questions is the focus of the current work.Technological development, R&D, networks
Reflexiones e interrogantes sobre el impacto del COVID-19 en la dinámica futura de las cadenas globales de valor
Get PDFRevista con referatoFil: Barletta, Florencia. Universidad Nacional de General Sarmiento. Instituto de Industria; Argentina.Fil: Yoguel, Gabriel. Universidad Nacional de General Sarmiento. Instituto de Industria; Argentina.El objetivo de esta nota es reflexionar sobre el impacto que el COVID-19 genera y seguirá generando en el proceso de producción mundial que se articula fundamentalmente en torno a las cadenas globales de valor (CGV). Para ello, pensamos que el análisis requiere tomar en cuenta la amplia literatura internacional sobre sistemas complejos que anidan en las CGV. Desde esta perspectiva, consideramos que un sistema económico está conformado por múltiples subsistemas interrelacionados de diverso grado de desarrollo, integrados a la vez por diversas organizaciones (empresas e instituciones) que realizan interacciones entre sí que van más allá de las transacciones de compra venta coordinadas por el mercado. En especial, un sistema es complejo cuando está compuesto por múltiples actores que interactúan en una forma no lineal de modo que el agregado es mayor que la suma de las partes. En estos sistemas las propiedades del agregado son “emergentes”. Asimismo, estos sistemas son: i) modulares, porque están formados por un conjunto de partes específicas, funcionales y conectadas; ii) abiertos, porque sus partes interactúan con ciertos grados de libertad y pueden cambiar sus conexiones y iii) jerárquicos, porque cada módulo es un sistema complejo.The objective of this note is to reflect on the impact that COVID-19 generates and will continue to generate in the global production process that is fundamentally articulated around global value chains (GVC). To do this, we think that the analysis requires taking into account the extensive international literature on complex systems nested in GVCs. From this perspective, we consider that an economic system is made up of multiple interrelated subsystems of varying degrees of development, integrated at the same time by various organizations (companies and institutions) that carry out interactions with each other that go beyond the purchase and sale transactions coordinated by the market. In particular, a system is complex when it is composed of multiple actors interacting in a non-linear manner such that the aggregate is greater than the sum of the parts. In these systems the properties of the aggregate are “emergent”. Likewise, these systems are: i) modular, because they are made up of a set of specific, functional and connected parts; ii) open, because its parts interact with certain degrees of freedom and can change their connections and iii) hierarchical, because each module is a complex system.O objetivo desta nota é refletir sobre o impacto que a COVID-19 gera e continuará a gerar no processo produtivo global que está fundamentalmente articulado em torno das cadeias globais de valor (CGV). Para fazer isso, pensamos que a análise requer levar em conta a extensa literatura internacional sobre sistemas complexos aninhados em CGVs. Nessa perspectiva, consideramos que um sistema econômico é constituído por múltiplos subsistemas inter-relacionados e de diversos graus de desenvolvimento, integrados ao mesmo tempo por diversas organizações (empresas e instituições) que realizam interações entre si que vão além da compra e venda. transações coordenadas pelo mercado. Em particular, um sistema é complexo quando é composto por múltiplos intervenientes que interagem de uma forma não linear, de modo que o agregado é maior que a soma das partes. Nestes sistemas as propriedades do agregado são “emergentes”. Da mesma forma, estes sistemas são: i) modulares, porque são constituídos por um conjunto de peças específicas, funcionais e interligadas; ii) aberto, porque suas partes interagem com certos graus de liberdade e podem alterar suas conexões e iii) hierárquico, porque cada módulo é um sistema complexo
Reflexiones e interrogantes sobre el impacto del COVID-19 en la dinámica futura de las cadenas globales de valor
Get PDFEl objetivo de esta nota es reflexionar sobre el impacto que el COVID-19 genera y seguirá generando en el proceso de producción mundial que se articula fundamentalmente en torno a las cadenas globales de valor (CGV). Para ello, pensamos que el análisis requiere tomar en cuenta la amplia literatura internacional sobre sistemas complejos que anidan en las CGV. Desde esta perspectiva, consideramos que un sistema económico está conformado por múltiples subsistemas interrelacionados de diverso grado de desarrollo, integrados a la vez por diversas organizaciones (empresas e instituciones) que realizan interacciones entre sí que van más allá de las transacciones de compra venta coordinadas por el mercado. En especial, un sistema es complejo cuando está compuesto por múltiples actores que interactúan en una forma no lineal de modo que el agregado es mayor que la suma de las partes. En estos sistemas las propiedades del agregado son “emergentes”. Asimismo, estos sistemas son: i) modulares, porque están formados por un conjunto de partes específicas, funcionales y conectadas; ii) abiertos, porque sus partes interactúan con ciertos grados de libertad y pueden cambiar sus conexiones y iii) jerárquicos, porque cada módulo es un sistema complejo
Experimental investigation into the effect of substrate clamping on the piezoelectric behaviour of thick-film PZT elements
No full textThis paper details an experimental investigation of the clamping effect associated with thick-film piezoelectric elements printed on a substrate. The clamping effect reduces the measured piezoelectric coefficient, d33, of the film. This reduction is due to the influence of the d31 component in the film when a deformation of the structure occurs, by either the direct or indirect piezoelectric effect. Theoretical analysis shows a reduction in the measured d33 of 62%, i.e. a standard bulk lead zirconate titanate (PZT)-5H sample with a manufacturer specified d33 of 593pC/N would fall to 227.8pC/N. To confirm this effect, the d33 coefficients of five thin bulk PZT-5H samples of 220µm thickness were measured before and after their attachment to a metallized 96% alumina substrate. The experimental results show a reduction in d33 of 74% from 529pC/N to 139pC/N. The theoretical analysis was then applied to existing University of Southampton thick-film devices. It is estimated that the measured d33 value of 131pC/N of the thick-film devices is the equivalent of an unconstrained d33 of 345pC/N
Acoustic tractor beam
Get PDFNegative radiation forces act opposite to the direction of propagation, or net momentum, of a beam but have previously been challenging to definitively demonstrate. We report an experimental acoustic tractor beam generated by an ultrasonic array operating on macroscopic targets (> 1 cm) to demonstrate the negative radiation forces, and to map out regimes over which they dominate, which we compare to simulations. The result and the geometrically simple configuration show that the effect is due to non-conservative forces, produced by redirection of a momentum flux from the angled sides of a target, and not by conservative forces from a potential energy gradient. Use of a simple acoustic setup provides an easily understood illustration of the negative radiation pressure concept for tractor beams, and demonstrates continuous attraction towards the source, against a net momentum flux in the system
Lattice cluster theory for the packing of rods on a lattice: Extension to treat anisotropic orientational distributions
No full textUnderstanding of the Meaning of Life as Envisioned by the Population of the Krasnoyarsk Region: The Structure and Dynamics (1991–2016)
No full textЦель статьи заключается в анализе малоизученных изменений, произошедших в структуре смысложизненных представлений и ценностных ориентаций населения Красноярского края за 26-летний период в условиях смены в стране общественно-экономического строя. Смысл жизни респондентов анализируется в двух его ипостасях: представлениях о желаемом будущем, а также ориентациях на терминальные и инструментальные ценности. В основе статьи лежат результаты пяти репрезентативных исследований, проведенных в регионе методом формализованного интервью с использованием сопоставимых методик. Полученные данные анализировались с помощью методов математической статистики (корреляционный, факторный анализ). Используется понятие иерархического уровня ценностных ориентаций по семиуровневой шкале потребностей в соответствии с модифицированной «пирамидой потребностей Маслоу». Происходящие трансформации смысложизненных представлений и ориентаций населения региона исследуются также в контексте дихотомии модусов «бытия» и «обладания» (Э. Фромм). Выделены три типа образа желаемого будущего: «Материальный достаток и престиж», «Семья и работа», «Духовное и нравственное развитие», проанализированы их социальные и ценностные характеристики. Установлено, что комплекс ориентаций на тип образа желаемого будущего «Материальный достаток» и связанные с ним терминальные и инструментальные ценности наиболее соответствуют сложившемуся в нашей стране типу общественного устройства. Показано, что за исследуемый период в массовом сознании населения Красноярского края произошло усиление престижно-потребительских, гедонистических и семейно-престижных смысложизненных ориентаций. В региональном социуме широко востребованы социальные практики, основанные на ценностях низких уровней, близких к полюсу «Обладание». Соответственно, он находится в состоянии перехода от стадии выживания к стадии развития. За исследуемый период почти вдвое выросла уверенность респондентов в реализации своего образа желаемого будущего. Делается вывод о социально-психологической и нравственной адаптации значительной части населения региона к сложившейся общественной ситуации. Распространение среди населения смысложизненных представлений и ориентаций низких уровней выступает важным фактором, который детерминирует продолжение социальных изменений, препятствующих переходу общества на более высокий уровень развития.This article aims to analyse the uncharted changes in the structure of the life attitudes and value orientations of the population in the Krasnoyarsk Region for the 26 years of the country’s socio-economic shift. The author analyses the respondents’ meaning of life in its two roles: 1) the prospects for the desired future and 2) the orientations at finite and pragmatic values. This study relies on five representative studies in the region with the help of formalised interviews with comparable methodologies. The analysis of the data obtained has employed the methods of mathematical statistics (correlation and factor analysis). The author uses the notion of hierarchical level of value orientations on a 7-level scale of needs, in accordance with a modified Maslow’s hierarchy of needs. The study covers occurring transformation of life attitudes and orientations of the region’s population as well in the context of E. Fromm’s dichotomy of “being” and “having”. The results show three image types of the desired future, the social values and characteristics of which were analysed then: 1) “Material wealth and prestige”, 2) “Work and family”, and 3) “Spiritual and moral development”. The author establishes that the set of attitudes referring to the desired future’s image type “Material wealth” and the related finite and pragmatic values correspond to the prevailing the type of social order in Russia. He shows that, in the mass consciousness of the Krasnoyarsk Territory’s population, there was a rise in the value orientations involving prestige-consumerism, hedonism, and family-prestige. The regional society requires more social practices based on values of lower levels close to the pole of “having”. Accordingly, it is transitioning from the survival to development stage. During the study period, the respondents’ confidence in fulfilling their image of the desired future nearly doubled. The author concludes that a large part of the regions’ population adapts to the current social situation socially, psychologically, and morally. The spread of the public life views and orientations of lower levels is an important factor that determines the continued social change, which prevent the society from achieving a higher level of development
