Linear resolutions of powers and products

The goal of this paper is to present examples of families of homogeneous ideals in the polynomial ring over a field that satisfy the following condition: every product of ideals of the family has a linear free resolution. As we will see, this condition is strongly correlated to good primary decompositions of the products and good homological and arithmetical properties of the associated multi-Rees algebras. The following families will be discussed in detail: polymatroidal ideals, ideals generated by linear forms and Borel fixed ideals of maximal minors. The main tools are Gr\"obner bases and Sagbi deformation

Osteosarcoma: correlation between radiological and histological changes after intra-arterial chemotherapy

The statistical correlation between three different radiological methods (conventional radiography, computed tomography and angiography) and tumor necrosis (TN) of the resected specimen have been studied in a series of 31 patients diagnosed with osteosarcoma (OS). They were treated with a multidisciplinary approach including intraarterial and intravenous chemotherapy followed by limb salvage procedures, plus intraoperative radiotherapy and adjuvant chemotherapy. A clear statistical correlation has been obtained between TN and angiography (p = 0.02) and between TN and two specific radiological signs: 'tumoral stain and neovascularity' (p = 0.02) and 'peritumoral fat planes' (p = 0.05). Conventional radiography, computed tomography and other radiological signs studied (nutrient vessel, soft tissue mass and central peripheral calcifications) did not show any significant correlation with TN. These results seem to suggest that angiography is a method to evaluate TN preoperatively and also to define the efficacy of neoadjuvant chemotherapy in OS

No measure for culture? Value in the new economy

This paper explores articulations of the value of investment in culture and the arts through a critical discourse analysis of policy documents, reports and academic commentary since 1997. It argues that in this period, discourses around the value of culture have moved from a focus on the direct economic contributions of the culture industries to their indirect economic benefits. These indirect benefits are discussed here under three main headings: creativity and innovation, employability, and social inclusion. These are in turn analysed in terms of three forms of capital: human, social and cultural. The paper concludes with an analysis of this discursive shift through the lens of autonomist Marxist concerns with the labour of social reproduction. It is our argument that, in contemporary policy discourses on culture and the arts, the government in the UK is increasingly concerned with the use of culture to form the social in the image of capital. As such, we must turn our attention beyond the walls of the factory in order to understand the contemporary capitalist production of value and resistance to it. </jats:p

Enhancing legume ecosystem services through an understanding of plant–pollinator interplay

Legumes are bee-pollinated, but to a different extent. The importance of the plant– pollinator interplay (PPI), in flowering crops such as legumes lies in a combination of the importance of pollination for the production service and breeding strategies, plus the increasing urgency in mitigating the decline of pollinators through the development and implementation of conservation measures. To realize the full potential of the PPI, a multidisciplinary approach is required. This article assembles an international team of genebank managers, geneticists, plant breeders, experts on environmental governance and agro-ecology, and comprises several sections. The contributions in these sections outline both the state of the art of knowledge in the field and the novel aspects under development, and encompass a range of reviews, opinions and perspectives. The first three sections explore the role of PPI in legume breeding strategies. PPI based approaches to crop improvement can make it possible to adapt and re-design breeding strategies to meet both goals of: (1) optimal productivity, based on an efficient use of pollinators, and (2) biodiversity conservation. The next section deals with entomological aspects and focuses on the protection of the “pest control service” and pollinators in legume crops. The final section addresses general approaches to encourage the synergybetweenfoodproductionandpollinationservicesatfarmerfieldlevel.Twobasic approaches are proposed: (a) Farming with Alternative Pollinators and (b) Crop Design System

Modelo Matemático No-Lineal para un Servosistema Neumático de Posicionamiento Preciso

En este artículo se presenta en detalle el modelado matemático no-lineal de un servomecanismo neumático de posicionamiento. El servomecanismo neumático está compuesto en su estructura básica por un cilindro sin vástago gobernado por una válvula proporcional de vías. Para la elaboración del modelo se tuvo en cuenta la dinámica del cilindro, propiedades del fluido de trabajo y características de la válvula. El modelo de los flujos de masa a través de la válvula se basó en el modelo de la norma ISO 6358,y los parámetros se obtuvieron por medio de técnicas no-lineales de optimización a partir de datos experimentales tomados en estado transitorio. La validación del modelo dinámico del sistema se realizó para diferentes señales de entrada y se comparó con resultados obtenidos experimentalmente.In this paper, a nonlinear mathematical model of a servo pneumatic positioning system is developed in detail. The systemis compound in its basic structure for a double-acting cylinder without piston rod which is controlled by a proportional valve.For the elaboration of model were taken in account the cylinder dynamics, work fluid properties and valve characteristics. Themass flow model is based on the model of standard ISO 6358, and the system parameters were estimated by means of nonlinear optimization techniques from experimental data in transient state. Validation of system dynamic model was made for different input signals and compared with experimental results

Modelo Matemático No-Lineal para un Servosistema Neumático de Posicionamiento Preciso

In this paper, a nonlinear mathematical model of a servo pneumatic positioning system is developed in detail. The systemis compound in its basic structure for a double-acting cylinder without piston rod which is controlled by a proportional valve.For the elaboration of model were taken in account the cylinder dynamics, work fluid properties and valve characteristics. Themass flow model is based on the model of standard ISO 6358, and the system parameters were estimated by means of nonlinear optimization techniques from experimental data in transient state. Validation of system dynamic model was made for different input signals and compared with experimental results.En este artículo se presenta en detalle el modelado matemático no-lineal de un servomecanismo neumático de posicionamiento. El servomecanismo neumático está compuesto en su estructura básica por un cilindro sin vástago gobernado por una válvula proporcional de vías. Para la elaboración del modelo se tuvo en cuenta la dinámica del cilindro, propiedades del fluido de trabajo y características de la válvula. El modelo de los flujos de masa a través de la válvula se basó en el modelo de la norma ISO 6358,y los parámetros se obtuvieron por medio de técnicas no-lineales de optimización a partir de datos experimentales tomados en estado transitorio. La validación del modelo dinámico del sistema se realizó para diferentes señales de entrada y se comparó con resultados obtenidos experimentalmente