A Newly Discovered Large and Significant Population of Castela emoryi (Emory’s Crucifixion Thorn, Simaroubaceae) in California

Castela emoryi is an understudied species, and recent visits to populations across California have shed new light on its distribution and biology, including recruitment, natural history, and herbivory. Field exploration in Rice Valley in Riverside County revealed what is considered to be the largest population of C. emoryi in California. Possible threats and conservation needs of this species are discussed

Identificação de parâmetros elásticos e piezoelétricos em estruturas activas tipo placa : técnicas de optimização clássica versus redes neuronais artificiais

Neste trabalho são apresentados dois métodos não destrutivos para a identificação de parâmetros elásticos e piezoeléctricos em estruturas laminadas activas do tipo placa, com sensores/actuadores de superfície. O primeiro destes métodos resolve o problema inverso através de métodos de optimização clássica, minimizando a diferença entre frequências naturais experimentais e as fornecidas por um modelo de elementos finitos. O segundo método baseia-se na construção de um “meta-modelo” do problema inverso, recorrendo a Redes Neuronais Artificiais. Os dois métodos são comparados recorrendo a resultados experimentais de uma placa em vibração livre

Impacto de los cambios tecnológicos en los modelos de negocios de las industrias de cultura y ocio en España - El caso de los museos y clubes de fútbol

En una primera instancia puede resultar sorprendente tratar en el mismo artículo organizaciones tan diferentes como los museos y los clubes de futbol. Sin embargo, en una mirada de más detalle se puede ver que ambas organizaciones cuentan con una relación muy estrecha en el plano emocional con sus seguidores. A partir de esta relación se analizan los múltiples cambios tecnológicos que pueden afectar a este sector, considerando los posibles efectos en modelos de negocio de éxito que se puedan adoptar en el futuro. El articulo culmina con una reflexión sobre las alternativas que el sector puede adoptar para continuar evolucionando sus modelos de negocio aprovechando los cambios tecnológicos identificados

Design of laminated structures using piezoelectric materials

Composite structures incorporating piezoelectric sensors and actuators are increasingly becoming important due to the offer of potential benefits in a wide range of engineering applications such as vibration and noise supression, shape control and precisition positioning. This paper presents a finit element formulation based on classical laminated plate theory for laminated structures with integrated piezoelectric layers or patches, acting as actuators. The finite element model is a single layer triangular nonconforming plate/shell element with 18 degrees of freedom for the generalized displacements, and one electrical potential degree of freedom for each piezsoelectric elementlayer or patch, witch are surface bonded on the laminate. An optimization of the patches position is performed to maximize the piezoelectric actuators efficiency as well as, the electric potential distribuition is search to reach the specified structure transverse displacement distribuition (shape control). A gradient based algorithm is used for this purpose. The model is applied in the optimization of illustrative laminated plate cases, and the results are presented and discussed

Shape control of laminated panels using piezoelectric actuators

This paper presents a finite element formulation based on the classical laminated plate theory for laminated structures with integrated piezoelectric layers or patches, acting as actuators.The finite element model is a single layer trinaguular nonconforming plate/shell element with 18 degrees of fredom for the generalized displacements, and one electrical potential degree of freedom for each piezoelectric element elemenet layer or patch. An optimization of the patches position is perfomed to maximize the piezoelectric actuators efficiency as well as,the electric potential distribution is serach to reach the specified strusctura transverse displacement distribution is search to reach the specified structures trsnsverse displacement distribution (shape control). A gradient based algorithm is used for this purpose.Results are presented and discussed

DNA Renaturation at the Water-Phenol Interface

We study DNA adsorption and renaturation in a water-phenol two-phase system, with or without shaking. In very dilute solutions, single-stranded DNA is adsorbed at the interface in a salt-dependent manner. At high salt concentrations the adsorption is irreversible. The adsorption of the single-stranded DNA is specific to phenol and relies on stacking and hydrogen bonding. We establish the interfacial nature of a DNA renaturation at a high salt concentration. In the absence of shaking, this reaction involves an efficient surface diffusion of the single-stranded DNA chains. In the presence of a vigorous shaking, the bimolecular rate of the reaction exceeds the Smoluchowski limit for a three-dimensional diffusion-controlled reaction. DNA renaturation in these conditions is known as the Phenol Emulsion Reassociation Technique or PERT. Our results establish the interfacial nature of PERT. A comparison of this interfacial reaction with other approaches shows that PERT is the most efficient technique and reveals similarities between PERT and the renaturation performed by single-stranded nucleic acid binding proteins. Our results lead to a better understanding of the partitioning of nucleic acids in two-phase systems, and should help design improved extraction procedures for damaged nucleic acids. We present arguments in favor of a role of phenol and water-phenol interface in prebiotic chemistry. The most efficient renaturation reactions (in the presence of condensing agents or with PERT) occur in heterogeneous systems. This reveals the limitations of homogeneous approaches to the biochemistry of nucleic acids. We propose a heterogeneous approach to overcome the limitations of the homogeneous viewpoint

Language and anxiety: an ethnographic study of international postgraduate students

This paper presents some findings from an ethnographic study of international postgraduate students at a university in the South of England, which involved interviews and participant observation over a twelve-month academic year. One of the major themes that emerged from this research was students’ anxiety over their level of English language. Although all students entered their course with a minimum level of IELTS 6, the majority felt disadvantaged by particularly poor spoken English, and suffered feelings of anxiety, shame and inferiority. Low self-confidence meant that they felt ill-equipped to engage in class discussion and in social interaction which used English as the medium of communication. A common reaction to stress caused by language problems was to retreat into monoethnic communication with students from the same country, further inhibiting progress in language. Whilst some linguistic progress was made by nearly all students during the academic sojourn, the anxiety suffered by students in the initial stage must not be underestimated, and appropriate support systems must be put in place to alleviate their distress