Absolutely Koszul algebras and the Backelin-Roos property

We study absolutely Koszul algebras, Koszul algebras with the Backelin-Roos property and their behavior under standard algebraic operations. In particular, we identify some Veronese subrings of polynomial rings that have the Backelin-Roos property and conjecture that the list is indeed complete. Among other things, we prove that every universally Koszul ring defined by monomials has the Backelin-Roos property

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

Epitaxial Co2Cr0.6Fe0.4Al thin films and magnetic tunneling junctions

Epitaxial thin films of the theoretically predicted half metal Co2Cr0.6Fe0.4Al were deposited by dc magnetron sputtering on different substrates and buffer layers. The samples were characterized by x-ray and electron beam diffraction (RHEED) demonstrating the B2 order of the Heusler compound with only a small partition of disorder on the Co sites. Magnetic tunneling junctions with Co2Cr0.6Fe0.4Al electrode, AlOx barrier and Co counter electrode were prepared. From the Julliere model a spin polarisation of Co2Cr0.6Fe0.4Al of 54% at T=4K is deduced. The relation between the annealing temperature of the Heusler electrodes and the magnitude of the tunneling magnetoresistance effect was investigated and the results are discussed in the framework of morphology and surface order based of in situ STM and RHEED investigations.Comment: accepted by J. Phys. D: Appl. Phy

Powers of componentwise linear ideals

We give criteria for graded ideals to have the property that all their powers are componentwise linear. Typical examples to which our criteria can be applied include the vertex cover ideals of certain finite graphs

On the symbolic powers of binomial edge ideals

We show that under some conditions, if the initial ideal in$_<(I)$ of an ideal $I$ in a polynomial ring has the property that its symbolic and ordinary powers coincide, then the ideal $I$ shares the same property. We apply this result to prove the equality between symbolic and ordinary powers for binomial edge ideals with quadratic Gr\"obner basis

Transforming Student Groups into Teams

The use of teams dominates the information system development process. Characteristics of teams have been identified that are indicative of self-managed teams. Knowledge of team operation and teamwork is important for IS students to possess. An educational strategy is proposed to assist students in IS programs in understanding the nature of teams and self-management techniques

Estimación computacional del error de discretización

Se demuestra que en las Aplicaciones de los Métodos Numericos a la Ingenieria, es necesario generar verificar Sucesiones Numéricas para obtener, a la vez, Soluciones Aproximadas y sus correspondientes Estimaciones de Error, requeridas, ambas, cuando no existe Solución Exacta o mientras no se disponga de Soluciones Experimentales clásicas. Se concluye que la Estimación Computacional presentada permite obtener, fácilmente, el Error de Discretizacidn en Aplicaciones del Método de los Elementos Finitos, generando y verificando una Sucesión de Aproximaciones especificas / uh 1 que, en determinadas condiciones, converge como una Serie Geometría de Razón conocida (r)

Determination of the calcium channel distribution in the olfactory system

In this paper we study a linear inverse problem with a biological interpretation, which is modeled by a Fredholm integral equation of the first kind. When the kernel in the Fredholm equation is represented by step func- tions, we obtain identifiability, stability and reconstruction results. Further- more, we provide a numerical reconstruction algorithm for the kernel, whose main feature is that a non-regular mesh has to be used to ensure the invert- ibility of the matrix representing the numerical discretization of the system. Finally, a second identifiability result for a polynomial approximation of degree less than nine of the kernel is also established

Koszul binomial edge ideals

It is shown that if the binomial edge ideal of a graph $G$ defines a Koszul algebra, then $G$ must be chordal and claw free. A converse of this statement is proved for a class of chordal and claw free graphs

Natural History of the Ahlstrom’s and Roose’s Prairies, Olympic National Park, Washington

The objective of this research is to evaluate the wetland and forest dynamics in and around the Ozette Prairies to identify their origin and history since the Last Ice Age. The Ozette Prairies are treeless areas, dominated by unique associations of understory species in an otherwise heavily forested region. The prairies are historically (pre-European) persistent elements of the landscape in a region where the climate promotes forest growth. Presently, the prairies are undergoing encroachment by the surrounding forest. The patchy character of the vegetation attests to centuries, or more, of climate change, expansion and demise of forest populations and changing fire regimes. We used a suite of methods to address the environmental history of this landscape. The first phase of this project evaluated the soils of the vicinity (this research is on-going). The soils indicate that fire has been an important component in their formation. The second phase of the project begins to evaluate the incidence of fire on this landscape. Three approaches where taken: examining sediments accumulated in wetlands within the prairies, examining repeat aerial photographs of the prairies to document tree invasion, and vegetation sampling to identify tree demographics