The Neron-Severi group of a proper seminormal complex variety

We prove a Lefschetz (1,1)-Theorem for proper seminormal varieties over the complex numbers. The proof is a non-trivial geometric argument applied to the isogeny class of the Lefschetz 1-motive associated to the mixed Hodge structure on H^2.Comment: 16 pages; Mathematische Zeitschrift (2008

Hirzebruch-Milnor classes and Steenbrink spectra of certain projective hypersurfaces

We show that the Hirzebruch-Milnor class of a projective hypersurface, which gives the difference between the Hirzebruch class and the virtual one, can be calculated by using the Steenbrink spectra of local defining functions of the hypersurface if certain good conditions are satisfied, e.g. in the case of projective hyperplane arrangements, where we can give a more explicit formula. This is a natural continuation of our previous paper on the Hirzebruch-Milnor classes of complete intersections.Comment: 15 pages, Introduction is modifie

Kinetic transcriptomic approach revealed metabolic pathways and genotoxic-related changes implied in the Arabidopsis response to ionising radiations

Plants exposed to ionising radiation (IR) have to face direct and indirect (oxidative stress) deleterious effects whose intensity depends on the dose applied and led to differential genome regulation. Transcriptomic analyses were conducted with CATMA microarray technology on Arabidopsis thaliana plantlets, 2 and 26 h after exposure to the IR doses 10 Gy and 40 Gy. 10 Gy treatment seemed to enhance antioxidative compound biosynthetic pathways whereas the 40 Gy dose up-regulated ROS-scavenging enzyme genes. Transcriptomic data also highlighted a differential regulation of chloroplast constituent genes depending on the IR dose, 10 Gy stimulating and 40 Gy down-regulating. This probable 40 Gy decrease of photosynthesis could help for the limitation of ROS production and may be coupled with programmed cell death (PCD)/senescence phenomena. Comparisons with previous transcriptomic studies on plants exposed to a 100 Gy dose revealed 60 dose-dependent up-regulated genes, including notably cell cycle checkpoints to allow DNA repairing phenomena. Furthermore, the alteration of some cellular structure related gene expression corroborated a probable mitotic arrest after 40 Gy. Finally, numerous heat-shock protein and chaperonin genes, known to protect proteins against stress-dependent dysfunction, were up-regulated after IR exposure

Regina Lectures on Fat Points

These notes are a record of lectures given in the Workshop on Connections Between Algebra and Geometry at the University of Regina, May 29--June 1, 2012. The lectures were meant as an introduction to current research problems related to fat points for an audience that was not expected to have much background in commutative algebra or algebraic geometry (although sections 8 and 9 of these notes demand somewhat more background than earlier sections).Comment: 32 pages, 3 figure

Differential Forms on Log Canonical Spaces

The present paper is concerned with differential forms on log canonical varieties. It is shown that any p-form defined on the smooth locus of a variety with canonical or klt singularities extends regularly to any resolution of singularities. In fact, a much more general theorem for log canonical pairs is established. The proof relies on vanishing theorems for log canonical varieties and on methods of the minimal model program. In addition, a theory of differential forms on dlt pairs is developed. It is shown that many of the fundamental theorems and techniques known for sheaves of logarithmic differentials on smooth varieties also hold in the dlt setting. Immediate applications include the existence of a pull-back map for reflexive differentials, generalisations of Bogomolov-Sommese type vanishing results, and a positive answer to the Lipman-Zariski conjecture for klt spaces.Comment: 72 pages, 6 figures. A shortened version of this paper has appeared in Publications math\'ematiques de l'IH\'ES. The final publication is available at http://www.springerlink.co

The Waldschmidt constant for squarefree monomial ideals

Given a squarefree monomial ideal $I \subseteq R =k[x_1,\ldots,x_n]$, we show that $\widehat\alpha(I)$, the Waldschmidt constant of $I$, can be expressed as the optimal solution to a linear program constructed from the primary decomposition of $I$. By applying results from fractional graph theory, we can then express $\widehat\alpha(I)$ in terms of the fractional chromatic number of a hypergraph also constructed from the primary decomposition of $I$. Moreover, expressing $\widehat\alpha(I)$ as the solution to a linear program enables us to prove a Chudnovsky-like lower bound on $\widehat\alpha(I)$, thus verifying a conjecture of Cooper-Embree-H\`a-Hoefel for monomial ideals in the squarefree case. As an application, we compute the Waldschmidt constant and the resurgence for some families of squarefree monomial ideals. For example, we determine both constants for unions of general linear subspaces of $\mathbb{P}^n$ with few components compared to $n$, and we find the Waldschmidt constant for the Stanley-Reisner ideal of a uniform matroid.Comment: 26 pages. This project was started at the Mathematisches Forschungsinstitut Oberwolfach (MFO) as part of the mini-workshop "Ideals of Linear Subspaces, Their Symbolic Powers and Waring Problems" held in February 2015. Comments are welcome. Revised version corrects some typos, updates the references, and clarifies some hypotheses. To appear in the Journal of Algebraic Combinatoric

Surface-functionalization with NFL peptide of Lipid NanoCapsules LNC: preferential entry into human glioblastoma cells

Glioblastoma (GBM) is one of the most fatal brain cancers with median survival of only 14.6 months. Hence, more efficacious therapies are necessary. Ferrocifen (FcTriOH) is an organometallic antitumor compound, selectively active on cancer cells [1]. However, this metallocomplexe is highly insoluble in water, requiring a formulation stage before being in vivo administered. Lipid nanocapsules (LNC), prepared via a solvent free process of emulsion phase inversion, could be a suitable vehicle for FcTriOH [2]. Moreover, NFL peptide is able to enter massively into glioblastoma cells, and poorly in healthy neurons and astrocytes (NHA) [3]. Indeed, the aim of the study was to evaluate the effect of the surface-functionalizing NFL concentrations on LNC uptake in U87MG human GBM cells. Moreover, FcTriOH was encapsulated in LNC and their in vitro efficacy on U87MG cells was evaluated. Finally, in vivo antitumor effect was evaluated in ectopic and orthotopic murine U87MG tumor models. Fluorescent LNC (F1), LNC with 0.86% w/w and LNC with 2.58% w/w surface-adsorbed NFL (F2 and F3 respectively) were prepared and characterized. FACS analysis revealed that cellular uptake of F3 into U87MG cells was 31.5 and 1.6-folds higher after 6 h compared to F1 and F2 respectively. Moreover, uptake of F3 was significantly higher in the GBM cells compared to NHA, whereas F1 was internalized preferentially in NHA. Uptake of F3 in U87MG cells was energy dependent. Macropinocytosis was possibly the major uptake pathway, followed by clathrin-dependent endocytosis. Then, FcTriOH loaded LNCs have been successfully prepared with a drug loading of 2.4 % and an encapsulation efficacy of 99 %. MTS assay on U87MG cells revealed an IC50 of 0.46 µM for F3-FcTriOH (free FcTriOH: IC50 = 1.31 µM). Preliminary in vivo experiments on subcutaneous U87MG tumor bearing nude mice showed significantly reduced relative tumor volume after two intravenous injections of F1-FcTriOH and F3-FcTriOH compared to saline. Moreover, intracranial administration of F3/F3-FcTriOH in orthotopic U87MG tumor bearing mice revealed 2 to 3-folds higher apparent diffusion coefficients (ADC) near the injection site in diffusion tensor imaging, compared to F1/F1-FcTriOH. Although dose adjustment will be necessary to avoid toxic effects, the results are promising as therapy induced increased ADC values could indicate possible cell necrosis/lysis.   References [1] Laine A.L. et al. (2014), Nanomedicine, 10, pp.1667-1677. [2] Heurtault B. et al. (2003), EJPS, 8, pp. 55-61. [3] Balzeau J. et al. (2013), Biomaterials, 34, pp.3381-3389

AID can restrict L1 retrotransposition suggesting a dual role in innate and adaptive immunity

Retrotransposons make up over 40% of the mammalian genome. Some copies are still capable of mobilizing and new insertions promote genetic variation. Several members of the APOBEC3 family of DNA cytosine deaminases function to limit the replication of a variety of retroelements, such as the long-terminal repeat (LTR)-containing MusD and Ty1 elements, and that of the non-LTR retrotransposons, L1 and Alu. However, the APOBEC3 genes are limited to mammalian lineages, whereas retrotransposons are far more widespread. This raises the question of what cellular factors control retroelement transposition in species that lack APOBEC3 genes. A strong phylogenetic case can be made that an ancestral activation-induced deaminase (AID)-like gene duplicated and diverged to root the APOBEC3 lineage in mammals. Therefore, we tested the hypothesis that present-day AID proteins possess anti-retroelement activity. We found that AID can inhibit the retrotransposition of L1 through a DNA deamination-independent mechanism. This mechanism may manifest in the cytoplasmic compartment co- or posttranslationally. Together with evidence for AID expression in the ovary, our data combined to suggest that AID has innate immune functions in addition to its integral roles in creating antibody diversity

Nursing Care of Patients With Cirrhosis: The LiverHope Nursing Project

Cirrhosis is a complex disease that is associated with disturbances in different organs besides the liver, including kidneys, heart, arterial circulation, lungs, gut, and brain. As a consequence, patients develop a number of complications that result in frequent hospital admissions and high morbidity and mortality. Patients with cirrhosis require constant and rigorous monitoring both in and outside the hospital. In this context, the role of nurses in the care of patients with cirrhosis has not been sufficiently emphasized and there is very limited information about nursing care of patients with cirrhosis compared with other chronic diseases. The current article provides a review of nursing care for the different complications of patients with cirrhosis. Nurses with specific knowledge on liver diseases should be incorporated into multidisciplinary teams managing patients with cirrhosis, both inpatient and outpatient. Conclusion: Nurses play an important role in the management and prevention of complications of the disease and improvement in patients' quality of life and bridge the gap between clinicians and families, between primary care and hospital care, and provide medical education to patients and caregivers