Families of determinantal schemes

Given integers a_0 \le a_1 \le ... \le a_{t+c-2} and b_1 \le ... \le b_t, we denote by W(b;a) \subset Hilb^p(\PP^{n}) the locus of good determinantal schemes X \subset \PP^{n} of codimension c defined by the maximal minors of a t x (t+c-1) homogeneous matrix with entries homogeneous polynomials of degree a_j-b_i. The goal of this short note is to extend and complete the results given by the authors in [10] and determine under weakened numerical assumptions the dimension of W(b;a), as well as whether the closure of W(b;a) is a generically smooth irreducible component of the Hilbert scheme Hilb^p(\PP^{n}).Comment: The non-emptiness of W(b;a) is restated as (2.2) in this version; the codimension c=2 case in (2.5)-(2.6) is reconsidered, and c > 2 (c > 3) is now an assumption in (2.16)-(2.17). 13 page

Ideals generated by submaximal minors

The goal of this paper is to study irreducible families W(b;a) of codimension 4, arithmetically Gorenstein schemes X of P^n defined by the submaximal minors of a t x t matrix A with entries homogeneous forms of degree a_j-b_i. Under some numerical assumption on a_j and b_i we prove that the closure of W(b;a) is an irreducible component of Hilb^{p(x)}(P^n), we show that Hilb^{p(x)}(P^n) is generically smooth along W(b;a) and we compute the dimension of W(b;a) in terms of a_j and b_i. To achieve these results we first prove that X is determined by a regular section of the twisted conormal sheaf I_Y/I^2_Y(s) where s=deg(det(A)) and Y is a codimension 2, arithmetically Cohen-Macaulay scheme of P^n defined by the maximal minors of the matrix obtained deleting a suitable row of A.Comment: 22 page

Topological Vertex, String Amplitudes and Spectral Functions of Hyperbolic Geometry

We discuss the homological aspects of the connection between quantum string generating function and the formal power series associated to the dimensions of chains and homologies of suitable Lie algebras. Our analysis can be considered as a new straightforward application of the machinery of modular forms and spectral functions (with values in the congruence subgroup of $SL(2,{\mathbb Z})$) to the partition functions of Lagrangian branes, refined vertex and open string partition functions, represented by means of formal power series that encode Lie algebra properties. The common feature in our examples lies in the modular properties of the characters of certain representations of the pertinent affine Lie algebras and in the role of Selberg-type spectral functions of an hyperbolic three-geometry associated with $q$-series in the computation of the string amplitudes.Comment: Revised version. References added, results remain unchanged. arXiv admin note: text overlap with arXiv:hep-th/0701156, arXiv:1105.4571, arXiv:1206.0664 by other author

CVD of CrO2 Thin Films: Influence of the Deposition Parameters on their Structural and Magnetic Properties

This work reports on the synthesis of CrO2 thin films by atmospheric pressure CVD using chromium trioxide (CrO3) and oxygen. Highly oriented (100) CrO2 films containing highly oriented (0001) Cr2O3 were grown onto Al2O3(0001) substrates. Films display a sharp magnetic transition at 375 K and a saturation magnetization of 1.92 Bohr magnetons per f.u., close to the bulk value of 2 Bohr magnetons per f.u. for the CrO2. Keywords: Chromium dioxide (CrO2), Atmospheric pressure CVD, Spintronics.Comment: 5 pages, 6 figure

In vitro amplification of BVDV field strains isolated in Argentina: effect of cell line and culture conditions

The aim of this work was to study the in vitro amplification of BVDV (Pestivirus, Flaviridae) field isolates from Argentina in MDBK, BoTur and BHK-21 continuous cell lines. Field isolates 99/134 (mucosal disease), 00/693 (mucosal disease), 04P7016 (respiratory disease) and 04/89 (mucosal disease), genotype 1b, were used and compared with the Singer and NADL reference strains, genotype 1a. Additionally, cell lines derived from explants of bovine testis (RD-420), bovine uterus (NCL-1) and porcine kidney (PKZ) were tested as alternative substrates for BVDV propagation in vitro. The effect of cell line, harvest time and infection protocol was evaluated. The viral titers observed depended on the virus and harvest time but not on the infection protocol. We found that MDBK and BoTur cell lines were susceptible to the infection whereas BHK-21 and PKZ were not. NADL viral titers, 00/693 and 04/89, increased from 24 to 48 h p.i. in BoTur cells and then reached a plateau, whereas those of 99/134 and 04P7016 remained constant between 24 and 72 h p.i. BVDV Singer, on the other hand, presented a maximum titer at 24 h p.i. and then decreased. BVDV-NADL titers increased in MDBK and NCL-1 but not in RD-420 between 24 and 48 h p.i., and then decreased at 72 h p.i. These facts lead us to conclude that neither the subgenotypes (1a, 1b) nor the clinical symptoms of the animal from the virus had been isolated seem to affect the virus cell line kinetics of viral replication in vitro. On the other hand, the most homogenous behavior, the most similar replication curves, and highest titers observed in MDBK and NCL-1 seem to indicate that these lines are generally more susceptible to BVDV replication.The aim of this work was to study the in vitro amplification of BVDV (Pestivirus, Flaviridae) field isolates from Argentina in MDBK, BoTur and BHK-21 continuous cell lines. Field isolates 99/134 (mucosal disease), 00/693 (mucosal disease), 04P7016 (respiratory disease) and 04/89 (mucosal disease), genotype 1b, were used and compared with the Singer and NADL reference strains, genotype 1a. Additionally, cell lines derived from explants of bovine testis (RD420), bovine uterus (NCL-1) and porcine kidney (PKZ) were tested as alternative substrates for BVDV propagation in vitro. The effect of cell line, harvest time and infection protocol was evaluated. The viral titers observed depended on the virus and harvest time but not on the infection protocol. We found that MDBK and BoTur cell lines were susceptible to the infection whereas BHK-21 and PKZ were not. NADL viral titers, 00/693 and 04/89, increased from 24 to 48 h p.i. in BoTur cells and then reached a plateau, whereas those of 99/134 and 04P7016 remained constant between 24 and 72 h p.i. BVDV Singer, on the other hand, presented a maximum titer at 24 h p.i. and then decreased. BVDV-NADL titers increased in MDBK and NCL-1 but not in RD-420 between 24 and 48 h p.i., and then decreased at 72 h p.i. These facts lead us to conclude that neither the subgenotypes (1a, 1b) nor the clinical symptoms of the animal from the virus had been isolated seem to affect the virus cell line kinetics of viral replication in vitro. On the other hand, the most homogenous behavior, the most similar replication curves, and highest titers observed in MDBK and NCL-1 seem to indicate that these lines are generally more susceptible to BVDV replication.Fil: Odeón, Anselmo Carlos. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Leunda, Maria Rosa. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Faverin, Claudia. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Boynak, Natalia. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Vena, M. M.. Biogénesis-Bagó S. A.; ArgentinaFil: Zabal, O.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Virología; Argentin

The representation type of determinantal varieties

This work is entirely devoted to construct huge families of indecomposable arithmetically Cohen-Macaulay (resp. Ulrich) sheaves $\mathcal{E}$ of arbitrary high rank on a general standard (resp. linear) determinantal scheme $X \subset \mathbb{P}^n$ of codimension $c \geq 1, n-c \geq 1$ and defined by the maximal minors of a $t \times(t+c-1)$ homogeneous matrix $\mathcal{A}$. The sheaves $\mathcal{E}$ are constructed as iterated extensions of sheaves of lower rank. As applications: (1) we prove that any general standard determinantal scheme $X \subset \mathbb{P}^n$ is of wild representation type provided the degrees of the entries of the matrix $\mathcal{A}$ satisfy some weak numerical assumptions; and (2) we determine values of $t, n$ and $n-c$ for which a linear standard determinantal scheme $X \subset \mathbb{P}^n$ is of wild representation type with respect to the much more restrictive category of its indecomposable Ulrich sheaves, i.e. $X$ is of Ulrich wild representation type

Effect of quality, porosity and density on the compression properties of cork

The compression properties of cork were studied on samples obtained from cork planks of two commercial quality classes (good and poor quality), with densities ranging from 0.12–0.20g cm-3 and porosities from 0.5 to 22.0%. The stress-strain curves were characterized by an elastic region up to approximately 5% strain, followed by a large plateau up to 60% strain caused by the progressive buckling of cell walls, and a steep stress increase for higher strains corresponding to cell collapse. The direction of compression was a highly significant factor of variation, with cork showing higher strength for the radial compression. Density influenced compression and cork samples with higher density showed overall larger resistance to compression in the three directions. In the elastic region, an exponential model of Young’s modulus in function of cork density could be adjusted. The effect of porosity on compression was small and the stress-strain curves were similar regardless of the porosity of the samples, although there was a trend toward an overall increase of stress with porosity for higher strains. Porosity was characterised by a high variability in the anatomical features of the lenticular filling material and the presence of collapsed and thick walled lignified cells. The inclusion of a porosity parameter for the modelling of the elastic modulus did not improve the prediction obtained with density-based models. There was no significant difference in the compression properties of cork samples obtained from cork planks of good and poor quality classes.info:eu-repo/semantics/publishedVersio

Tensile properties of cork in axial stress and influence of porosity, density, quality and radial position in the plank

The behaviour of cork under tensile stress in the axial direction was studied for samples taken from cork planks of good (class 1) and poor (class 4) quality grades and at three radial positions within the plank (inner, mid and outer positions). The effect of cork density (ranging from 0.123 to 0.203 g cm−3) and porosity (ranging from 2.8 to 9.6% in the tangential surface) on Young’s modulus and fracture stress and strain was studied. The tensile stress-strain curves of cork showed an elastic deformation up to 2% strain with a Young’s modulus of 30.8 MPa, and a fracture stress of 1.05 MPa at a strain of 7.1% for class 1, and Young’s modulus of 26.1 MPa, and a fracture stress of 0.77 MPa at a strain of 5.5% for class 4. Fracture always started at a pore. The quality class and the radial position in the plank were highly significant factors of the tensile properties variation with good quality cork in the inner part of the plank showing the highest strength. Density influenced the elastic behaviour of cork with a highly significant correlation of increasing E with density, but not so clearly the fracture stress and strain. The variability of tensile properties with porosity was large and although significant, the correlations were lower in spite of a decreasing trend of E with porosity. Fracture depended on the type of defects in corkinfo:eu-repo/semantics/publishedVersio