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

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

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

Foraminiferal biodiversity associated with cold-water coral carbonate mounds and open slope of SE Rockall Bank (Irish continental margin-NE Atlantic)

Cold-water coral (CWC) ecosystems are hotspots of macro- and microfaunal biodiversity and provide refuge for a wide variety of deep-sea species. We investigated how the abundance and biodiversity of 'live' (Rose Bengal stained) foraminifera varies with, and is related to, the occurrence of CWC on the Rockall Bank (NE Atlantic). Qualitative and quantitative analyses were performed on 21 replicate samples from 8 deep-sea stations, including 4 stations on CWC-covered carbonate mounds at depths of 567-657 m, and 4 stations on the adjacent slope at depths of 469-1958 m where CWC were absent. This sampling strategy enabled us to demonstrate that sediments surrounding the living CWC were characterised by higher foraminiferal abundance and biodiversity than open-slope sediments from the same area. A total of 163 foraminiferal species was identified. The dominant species in CWC sediments were: Spirillina vivipara, Allogromiid sp. 1. Globocassidulina subglobosa, Adercotryma wrighti, Eponides pusillus, Ehrenbergina carinata, Planulina ariminensis, Trochammina inflate and Paratrochammina challenged. Foraminifera were nearly absent in adjacent open slope areas subject to strong tidal currents and characterised by coarse grained deposits. We suggest that CWC create a heterogeneous three-dimensional substrate offering microhabitats to a diverse benthic foraminiferal community

A Superconductor Made by a Metal Heterostructure at the Atomic Limit Tuned at the "Shape Resonance": MgB2

We have studied the variation of Tc with charge density and lattice parameters in Mg1-xAlxB2 superconducting samples at low Al doping x<8%. We show that high Tc occurs where the chemical potential is tuned at a "superconducting shape resonance" near the energy Ec of the quantum critical point (QCP) for the dimensional transition from 2D to 3D electronic structure in a particular subband of the natural superlattice of metallic atomic boron layers. At the "shape resonance" the electrons pairs see a 2D Fermi surface at EF-w0 and a 3D Fermi surface at EF+wo, where wo is the energy cut off of the pairing interaction. The resonant amplification occurs in a narrow energy range where EF-Ec is in the range of 2wo.Comment: 16 page

Occupy: 'struggles for the common or an 'anti-politics of dignity? Reflections on Hardt and Negri and John Holloway

This article provides a critical examination of Michael Hardt and Antonio Negri’s and John Holloway’s theory of revolutionary subjectivity, and does so by applying their theories to the Occupy movement of 2011. Its central argument is that one should avoid collapsing ‘autonomist’ and ‘open’ Marxism, for whilst both approaches share Tronti’s (1979) insistence on the constituent role of class struggle, and also share an emphasis on a prefigurative politics which engages a non-hierarchical and highly participatory politics, there nevertheless remain some significant differences between their approaches. Ultimately, when applied to Occupy Movement whilst their theory isn’t entirely unproblematic, I will argue that Hardt and Negri’s ‘autonomist’ approach offers the stronger interpretation, due mainly to their revised historical materialism

Performance Of A Liquid Argon Time Projection Chamber Exposed To The WANF Neutrino Beam

We present the results of the first exposure of a Liquid Argon TPC to a multi-GeV neutrino beam. The data have been collected with a 50 liters ICARUS-like chamber located between the CHORUS and NOMAD experiments at the CERN West Area Neutrino Facility (WANF). We discuss both the instrumental performance of the detector and its capability to identify and reconstruct low multiplicity neutrino interactions.Comment: 14 pages, 12 figures. Submitted for publication to Physical Review