Quantum phase transitions in the S=1/2 distorted diamond chain

By means of the second derivative of the ground-state and first-excited energy, the quantum phase transitions (QPTs) for the distorted diamond chain (DDC) with ferromagnetic and antiferromagnetic frustrated interactions and the trimerized case are investigated, respectively. Our results show the plentiful quantum phases owing to the spin interaction competitions in the model. Meanwhile, by using the transfer-matrix renormalization-group technique, we study the two-site thermal entanglement of the DDC model in the thermodynamic limit for a further understanding of the QPTs.

Generalized Viscoplastic Modeling of Debris Flow

Various concepts have been proposed or used in the development of rheological models for debris flow. The earliest model developed by Bagnold was based on the concept of the “dispersive” pressure generated by grain collisions. Bagnold’s concept appears to be theoretically sound, but his empirical model has been found to be inconsistent with most theoretical models developed from non-Newtonian fluid mechanics. Although the generality of Bagnold’s model is still at issue, debris-flow modelers in Japan have generally accepted Takahashi’s formulas derived from Bagnold’s model. Some efforts have recently been made by theoreticians in non-Newtonian fluid mechanics to modify or improve Bagnold’s concept or model. A viable rheological model should consist both of a rate-independent part and a rate-dependent part. A generalized viscoplastic fluid (GVF) model that has both parts as well as two major rheological properties (i.e., the normal stress effect and soil yield criterion) is shown to be sufficiently accurate, yet practical, for general use in debris-flow modeling. In fact, Bagnold’s model is found to be only a particular case of the GVF model. Analytical solutions for (steady) uniform debris flows in wide channels are obtained from the GVF model based on Bagnold’s simplified assumption of constant grain concentration.

带参并发系统的模型检测

带参并发系统 实际包含一族并发系统实例，其中以一个（或多个）参数表示每个系统实例的规模，比如实例系统中 并发执行的进程个数或数据域的大小。带参模型检测的任务是验证 对任意的参数数值，所有的系统实例都满足所期望的性质。本文研究带参并发系统的模型检测方法和技术。 一般来说， 带参系统的参数不仅代表进程个数，也可以是通信缓冲区容量、数据域大小、数据通路宽度等。然而迄今为止，该领域的绝大多数研究都 针对前者类型的参数，而往往忽视数据方面的参数。本文中，我们提出基于带符号迁移图的复合型带参网络协议建模框架。 系统表示为顺序结构的“结点进程”的并发复合，彼此通过“信道进程”进行通讯；性质以一种嵌套谓词等式系形式的一阶$\mu$ 演算表达；进而相应扩展由实验室自主开发的传值进程模型检测工具，对于数据带参的并发系统给出有效的验证方法， 并且对于一些典型的带参系统作出实例研究。 出乎意料的是，在GERMAN2004 协议的缓存一致性已经被其他研究者证明正确的情况下，我们却发现了它在于数据一致性方面的一个严重错误，并予以更正。 进一步，应用我们检测工具中所实现的“数据无关”技术，我们有效推广了研究结论，证明了对于任意大小的数据域， 修改后的GERMAN协议仍然保证满足数据一致性要求。 环境抽象的方法将计数抽象的思想借鉴到谓词抽象的技术中，对于控制带参的并发系统给出一般性验证框架。然而该方法具有相当 高的复杂度；对于很多实际应用的系统而言，所构造的抽象系统规模仍然超出常用模型检测工具所能处理的范围。为了克服这个困难， 我们提出了{\em 状态聚类}方法，在 局部可达性分析的基础上，通过对系统表达式的分析把全部可达的局部状态分组成为少数几个状态簇。在进行 状态聚类的启发式算法中，我们采用了先分裂后聚合的策略，即在识别出不同类的具有代表性的状态配置后，再将类似的状态尽可能 合并到同一个状态簇。这样局部状态被相应划分成为若干等价类，每个类以一个单元状态为代表。然后我们在系统描述的层次上， 通过程序重写的方式直接构造生成对应的抽象系统。 实例研究显示，状态聚类方法通常能够将抽象节点的大小缩减约3个数量级。 参数抽象作为带参系统的安全性性质验证的另外一个有效方法，其最困难之处在于找到合适的辅助不变量，用以进行卫加强 以精化抽象模型。针对这个问题，我们提出一种启发式的方法，通过在参考模型中计算自动产生辅助不变量。 利用这一技术，我们将参数截断的思想应用于 处理环境抽象中依赖于参数类型的复杂变量，使得环境抽象在状态聚类后得到进一步优化。我们有效结合了参数抽象与环境抽象技术， 显著降低了抽象系统状态空间规模，从而极大节省了模型检测的内存开销；并且由于抽象中的每个 步骤都以现行的模型检测工具辅助计算，整个验证过程可以机械化完成，不需要过多的人工介入。作为示范，对于 工业应用的复杂的缓存一致性协议FLASH，我们在保留了其中最为著名的“三跳”事务处理的情况下，验证了缓存一致性和数据一致性。 据我们所知，这是首次这样工业实用的复杂协议能够同时在控制方面和数据方面在如此的精度上得到成功验证。

Magnetic frustration induced quantum phase transitions in the S=1/2 vertically asymmetric diamond chain

This work was supported by the National Basic Research Program of China (973 Program) grant No. G2009CB929300 and the National Natural Science Foundation of China under Grant Nos. 60521001 and 60776061.

Methods to study the ionic conductivity of polymeric electrolytes using a.c. impedance spectroscopy

Composite polymeric electrolytes of PEO-LiClO4-Al2O3 and PEO-LiClO4-EC were prepared and the ionic conductivity by a.c. impedance was calculated using four different methods, and three kinds of representations of a.c. impedance spectra were adopted. The first is based on the Nyquist impedance plot of the imaginary part (Z") versus the real part (Z') of the complex impedance. The second and the third correspond to the plots of imaginary impedance Z" as a function of frequency (f), and the absolute value (\Z\) and phase angle (theta) as a function of f, respectively. It was found that the values of the ionic conductivity calculated using the three representations of a.c. impedance spectra are basically identical.

3-D Vision and Figure-Ground Separation by Visual Cortex

A neural network theory of :3-D vision, called FACADE Theory, is described. The theory proposes a solution of the classical figure-ground problem for biological vision. It does so by suggesting how boundary representations and surface representations are formed within a Boundary Contour System (BCS) and a Feature Contour System (FCS). The BCS and FCS interact reciprocally to form 3-D boundary and surface representations that arc mutually consistent. Their interactions generate 3-D percepts wherein occluding and occluded object completed, and grouped. The theory clarifies how preattentive processes of 3-D perception and figure-ground separation interact reciprocally with attentive processes of spatial localization, object recognition, and visual search. A new theory of stereopsis is proposed that predicts how cells sensitive to multiple spatial frequencies, disparities, and orientations are combined by context-sensitive filtering, competition, and cooperation to form coherent BCS boundary segmentations. Several factors contribute to figure-ground pop-out, including: boundary contrast between spatially contiguous boundaries, whether due to scenic differences in luminance, color, spatial frequency, or disparity; partially ordered interactions from larger spatial scales and disparities to smaller scales and disparities; and surface filling-in restricted to regions surrounded by a connected boundary. Phenomena such as 3-D pop-out from a 2-D picture, DaVinci stereopsis, a 3-D neon color spreading, completion of partially occluded objects, and figure-ground reversals are analysed. The BCS and FCS sub-systems model aspects of how the two parvocellular cortical processing streams that join the Lateral Geniculate Nucleus to prestriate cortical area V4 interact to generate a multiplexed representation of Form-And-Color-And-Depth, or FACADE, within area V4. Area V4 is suggested to support figure-ground separation and to interact. with cortical mechanisms of spatial attention, attentive objcect learning, and visual search. Adaptive Resonance Theory (ART) mechanisms model aspects of how prestriate visual cortex interacts reciprocally with a visual object recognition system in inferotemporal cortex (IT) for purposes of attentive object learning and categorization. Object attention mechanisms of the What cortical processing stream through IT cortex are distinguished from spatial attention mechanisms of the Where cortical processing stream through parietal cortex. Parvocellular BCS and FCS signals interact with the model What stream. Parvocellular FCS and magnocellular Motion BCS signals interact with the model Where stream. Reciprocal interactions between these visual, What, and Where mechanisms arc used to discuss data about visual search and saccadic eye movements, including fast search of conjunctive targets, search of 3-D surfaces, selective search of like-colored targets, attentive tracking of multi-element groupings, and recursive search of simultaneously presented targets.

Empirical analysis and improved modelling of natural gas demand in Ireland

Countries across the world are being challenged to decarbonise their energy systems in response to diminishing fossil fuel reserves, rising GHG emissions and the dangerous threat of climate change. There has been a renewed interest in energy efficiency, renewable energy and low carbon energy as policy‐makers seek to identify and put in place the most robust sustainable energy system that can address this challenge. This thesis seeks to improve the evidence base underpinning energy policy decisions in Ireland with a particular focus on natural gas, which in 2011 grew to have a 30% share of Ireland’s TPER. Natural gas is used in all sectors of the Irish economy and is seen by many as a transition fuel to a low-carbon energy system; it is also a uniquely excellent source of data for many aspects of energy consumption. A detailed decomposition analysis of natural gas consumption in the residential sector quantifies many of the structural drives of change, with activity (R2 = 0.97) and intensity (R2 = 0.69) being the best explainers of changing gas demand. The 2002 residential building regulations are subject to an ex-post evaluation, which using empirical data finds a 44 ±9.5% shortfall in expected energy savings as well as a 13±1.6% level of non-compliance. A detailed energy demand model of the entire Irish energy system is presented together with scenario analysis of a large number of energy efficiency policies, which show an aggregate reduction in TFC of 8.9% compared to a reference scenario. The role for natural gas as a transition fuel over a long time horizon (2005-2050) is analysed using an energy systems model and a decomposition analysis, which shows the contribution of fuel switching to natural gas to be worth 12 percentage points of an overall 80% reduction in CO2 emissions. Finally, an analysis of the potential for CCS in Ireland finds gas CCS to be more robust than coal CCS for changes in fuel prices, capital costs and emissions reduction and the cost optimal location for a gas CCS plant in Ireland is found to be in Cork with sequestration in the depleted gas field of Kinsale.

Monte Carlo studies of quantum and classical annealing on a double well

We present results for a variety of Monte Carlo annealing approaches, both classical and quantum, benchmarked against one another for the textbook optimization exercise of a simple one-dimensional double well. In classical (thermal) annealing, the dependence upon the move chosen in a Metropolis scheme is studied and correlated with the spectrum of the associated Markov transition matrix. In quantum annealing, the path integral Monte Carlo approach is found to yield nontrivial sampling difficulties associated with the tunneling between the two wells. The choice of fictitious quantum kinetic energy is also addressed. We find that a "relativistic" kinetic energy form, leading to a higher probability of long real-space jumps, can be considerably more effective than the standard nonrelativistic one.

Optimization by quantum annealing: Lessons from simple cases

We investigate the basic behavior and performance of simulated quantum annealing (QA) in comparison with classical annealing (CA). Three simple one-dimensional case study systems are considered: namely, a parabolic well, a double well, and a curved washboard. The time-dependent Schrodinger evolution in either real or imaginary time describing QA is contrasted with the Fokker-Planck evolution of CA. The asymptotic decrease of excess energy with annealing time is studied in each case, and the reasons for differences are examined and discussed. The Huse-Fisher classical power law of double-well CA is replaced with a different power law in QA. The multiwell washboard problem studied in CA by Shinomoto and Kabashima and leading classically to a logarithmic annealing even in the absence of disorder turns to a power-law behavior when annealed with QA. The crucial role of disorder and localization is briefly discussed.

The effect of helium accretion efficiency on rates of Type Ia supernovae: Double detonations in accreting binaries

he double-detonation explosion scenario of Type Ia supernovae (SNe Ia) has gained increased support from the SN Ia community as a viable progenitor model, making it a promising candidate alongside the well-known single degenerate and double degenerate scenarios. We present delay times of double-detonation SNe, in which a sub-Chandrasekhar mass carbon–oxygen white dwarf (WD) accretes non-dynamically from a helium-rich companion. One of the main uncertainties in quantifying SN rates from double detonations is the (assumed) retention efficiency of He-rich matter. Therefore, we implement a new prescription for the treatment of accretion/accumulation of He-rich matter on WDs. In addition, we test how the results change depending on which criteria are assumed to lead to a detonation in the helium shell. In comparing the results to our standard case (Ruiter et al.), we find that regardless of the adopted He accretion prescription, the SN rates are reduced by only ∼25 per cent if low-mass He shells (≲0.05 M⊙) are sufficient to trigger the detonations. If more massive (0.1 M⊙) shells are needed, the rates decrease by 85 per cent and the delay time distribution is significantly changed in the new accretion model – only SNe with prompt (<500 Myr) delay times are produced. Since theoretical arguments favour low-mass He shells for normal double-detonation SNe, we conclude that the rates from double detonations are likely to be high, and should not critically depend on the adopted prescription for accretion of He.

Gestão da sustentabilidade nas organizações: uma nova metodologia

O presente trabalho pretende auxiliar o processo de consolidação do conceito de sustentabilidade no seio das organizações. Partindo de ferramentas de gestão e avaliação já existentes, esta tese sugere a sua integração numa única metodologia, ultrapassando desse modo as limitações e potenciando as suas capacidades enquanto ferramentas isoladas. O modelo proposto para o Sistema de Gestão da Sustentabilidade (SGS) integra assim: o conceito de melhoria contínua característico dos sistemas de gestão normalizados; a capacidade de tradução da perspetiva estratégica da gestão para o plano operacional, característica do Business Scorecard (BSC); e, por fim, a avaliação emergética é ainda utilizada como uma ferramenta de avaliação da sustentabilidade de sistemas. Um objetivo secundário desta tese prende-se com o desenvolvimento de um procedimento para a realização da análise emergética de um sistema. Depois de analisada a literatura referente à utilização da análise emergética, identificou-se como necessária a definição de um procedimento normalizado, adotando um conjunto de tarefas e um formato de apresentação de resultados que permita disseminar o conceito e tornar a ferramenta mais “utilizável”. Por outro lado, procurou-se dotar o procedimento com um conjunto de indicações que permitem ultrapassar limitações e inconvenientes apontados pelos críticos mas também utilizadores do método, nomeadamente: problemas de dupla contagem, cálculo da incerteza da análise e critérios de qualidade da informação utilizada. O modelo dos sistemas de gestão normalizados apresenta um papel central na metodologia proposta. O conceito de “melhoria contínua” afigura-se como fundamental num sistema que pretende implementar o conceito “desenvolvimento sustentável” e avaliar o seu desempenho à luz do mesmo. Assim, o ciclo Plan-Do-check-Act (PDCA) deve ser utilizado para implementar o SGS de acordo com uma Política para a Sustentabilidade que a organização deve desenvolver. Definida a Política, o modelo baseia-se então no ciclo PDCA: fase de planeamento; fase de implementação; fase de verificação; e fase de revisão. É na fase de planeamento do SGS que se sugere a introdução das outras duas ferramentas: a análise emergética (AEm) e o BSC. A fase de planeamento do modelo de SGS proposto neste trabalho foi aplicada à Universidade de Aveiro (UA), incluindo a definição de uma Política para a Sustentabilidade e o planeamento estratégico e operacional. A avaliação emergética à UA foi realizada recorrendo ao procedimento desenvolvido nesta tese e permitiu caracterizar e avaliar os fluxos de recursos que a “alimentam” sob uma só unidade, atribuindo deste modo graus de importância aos diferentes recursos utilizados. A informação representa 96% do total de recursos utilizados na UA, quando avaliados sob o ponto de vista emergética. Para além da informação, os fluxos financeiros representam a maior fatia do orçamento emergético da UA, grande parte dos quais serve para sustentar os serviços prestados pelo corpo docente da UA. Analisando valores históricos de 3 indicadores de desempenho emergético, observa-se que a UA não regista uma evolução positiva em nenhum dos indicadores: a emergia utilizada nos edifícios tem-se mantido mais ou menos constante; a retribuição emergética da UA para a sociedade, avaliada sobre a forma de diplomados, tem diminuído; e a relação emergética entre professores e alunos tem também diminuído, facto que pode refletir-se na qualidade dos “produtos” da UA. Da aplicação do SGS à UA regista-se: a adequabilidade do ciclo PDCA à implementação de um SGS; a capacidade da AEm “obrigar” a organização a adotar uma abordagem sistémica da sua atividade, resultando numa visão mais aprofundada da sua relação com o contexto ambiental, económico e social em que se insere; a importância da visão estratégica e da sua tradução em termos operacionais na fase de planeamento de um SGS; e, por fim, a capacidade de adaptação e dupla funcionalidade (implementação e avaliação) do modelo de SGS proposto. A metodologia de SGS proposta nesta tese, sendo direcionada para todo o tipo de organizações, não se desvirtua quando aplicada ao contexto específico das instituições de ensino superior e permite implementar e avaliar o conceito “desenvolvimento sustentável” nas quatro dimensões da universidade (Educação, Investigação, Operação; Relação com as partes interessadas).

Psychopathy and Aggression: Examining the Role of Empathy

Empirical research has consistently demonstrated a positive association between psychopathic traits and physical aggression (Campbell, Porter, & Santor, 2004; Gretton, Hare, & Catchpole, 2004; Raine et aI., 2006; Spain, Douglas, Poythress, & Epstein, 2004). Moreover, research has also found that the emotional/interpersonal (Factor 1) psychopathy traits tend to be more closely associated with goal oriented, proactive aggression, whereas the social deviance (Factor 2) psychopathy characteristics have been more closely linked to reactive aggression, which is perpetrated in response to threat or provocation (Flight & Forth, 2007). Blair (2004; 2005; 2006) has recently proposed the Integrated Emotions Systems Model (lES), which posits that the association between Factor 1 psychopathy traits and proactive aggression is due to amygdala dysfunction leading to failed moral socialization. Consequently, individuals who exhibit Factor 1 psychopathy traits do not experience affective empathy in response to distress cues exhibited by others, thus, preventing the inhibition of proactive aggression. The current investigation sought to test this model by examining the associations among the emotional/interpersonal (Factor 1) psychopathy traits, proactive aggression, and affective empathy. After accounting for head injury, Factor 2 psychopathy traits, reactive aggression, and cognitive empathy, it was hypothesized that 1) Factor 1 psychopathy traits would predict proactive aggression, and 2) that affective empathy is a common cause of Factor 1 psychopathy traits, proactive aggression, and of the relationship between these two constructs. This hypothesis assumed that (a) affective empathy would uniquely predict Factor 1 psychopathy traits, (b) that affective empathy would uniquely predict proactive aggression, and (c) that affective empathy would account for the relationship between Factor I psychopathy traits and proactive aggression. The total sample consisted of 137 male undergraduate students. Participants completed measures of psychopathy (SRP III; Paulhus, Hemphill, & Hare, in press), aggression (PCS; Marsee, Kimonis, & Frick, 2004; RPQ; Raine et at, 2006), dispositional cognitive and affective empathy (BES; Jolliffe & Farrington, 2006; TES; Spreng, McKinnon, Mar, & Levine, 2009), and situational cognitive and affective empathy in response to neutral and empathy eliciting video clips. Physiological indices (heart rate & electrodermal activity) of affective empathy were also obtained while participants viewed the neutral and empathy eliciting videos. Findings indicated that Factor I psychopathy traits predicted proactive aggression. In addition, results demonstrated that affective empathy predicted both Factor I psychopathy traits and proactive aggression. However, the association between affective empathy and proactive aggression appeared to be dependent on the conceptualization and measurement of affective empathy. Conversely, affective empathy did not appear to account for the relationship between Factor I psychopathy traits and proactive aggression. Overall, results demonstrated partial support for the IES model. Implications of the results, limitations of the study and future research directions are discussed.

Análisis del impacto del tamaño de los activos en la cuenta de resultados mediante la utilización de espacios de fase y análisis de recurrencia

Los resultados financieros de las organizaciones son objeto de estudio y análisis permanente, predecir sus comportamientos es una tarea permanente de empresarios, inversionistas, analistas y académicos. En el presente trabajo se explora el impacto del tamaño de los activos (valor total de los activos) en la cuenta de resultados operativos y netos, analizando inicialmente la relación entre dichas variables con indicadores tradicionales del análisis financiero como es el caso de la rentabilidad operativa y neta y con elementos de estadística descriptiva que permiten calificar los datos utilizados como lineales o no lineales. Descubriendo posteriormente que los resultados financieros de las empresas vigiladas por la Superintendencia de Sociedades para el año 2012, tienen un comportamiento no lineal, de esta manera se procede a analizar la relación de los activos y los resultados con la utilización de espacios de fase y análisis de recurrencia, herramientas útiles para sistemas caóticos y complejos. Para el desarrollo de la investigación y la revisión de la relación entre las variables de activos y resultados financieros se tomó como fuente de información los reportes financieros del cierre del año 2012 de la Superintendencia de Sociedades (Superintendencia de Sociedades, 2012).

Identificación y análisis de los factores que influyen en el desarrollo competitivo de empresas de base tecnológica en la industria del software colombiano

identificar los factores que influyen en el desarrollo exitoso de empresas que produzcan software en Colombia y qué dirección se les debe dar a estos, con el fin de orientar las actividades empresariales y gubernamentales hacia la generación de una estructura que facilite la creación y desarrollo de empresas de base tecnológica del sector.

Resiliencia organizacional y capital psicológico

Desde la noción universal sobre la empresa como un sistema de interacción con un entorno determinado para alcanzar un objetivo, de manera planificada y en función de satisfacer las demandas de un mercado mediante la actividad económica, su viabilidad, sostenibilidad y crecimiento dependerán, por supuesto, de una serie de estrategias adecuadas no solo para tales fines, sino también para enfrentar diversidad de agentes endógenos y exógenos que puedan afectar el normal desempeño de su gestión. Estamos hablando de la importancia de la resiliencia organizacional y del Capital Psicológico. En un escenario tan impredecible como el de la economía mundial, donde la constante son los cambios en su comportamiento —unos propios de su dinámica e interdependencia, naturales de fenómenos como la globalización, y otros derivados de eventos disruptivos— hoy más que nunca es necesario implementar el modelo de la empresa resiliente, que es aquella entidad capaz de adaptarse y recuperarse frente a una perturbación. Al mismo tiempo, más allá de su tamaño, naturaleza u objeto social, es indispensable reconocer básicamente que toda organización está constituida por personas, lo cual implica la trascendencia que para su funcionamiento tiene el factor humano-dependiente, y por lo tanto se crea la necesidad de promover el Capital Psicológico y la resiliencia a nivel de las organizaciones a través de una cultura empresarial.