An In Silico Model to Simulate the Evolution of Biological Aging

Biological aging is characterized by an age-dependent increase in the probability of death and by a decrease in the reproductive capacity. Individual age-dependent rates of survival and reproduction have a strong impact on population dynamics, and the genetic elements determining survival and reproduction are under different selective forces throughout an organism lifespan. Here we develop a highly versatile numerical model of genome evolution --- both asexual and sexual --- for a population of virtual individuals with overlapping generations, where the genetic elements affecting survival and reproduction rate at different life stages are free to evolve due to mutation and selection. Our model recapitulates several emerging properties of natural populations, developing longer reproductive lifespan under stable conditions and shorter survival and reproduction in unstable environments. Faster aging results as the consequence of the reduced strength of purifying selection in more unstable populations, which have large portions of the genome that accumulate detrimental mutations. Unlike sexually reproducing populations under constant resources, asexually reproducing populations fail to develop an age-dependent increase in death rates and decrease in reproduction rates, therefore escaping senescence. Our model provides a powerful in silico framework to simulate how populations and genomes change in the context of biological aging and opens a novel analytical opportunity to characterize how real populations evolve their specific aging dynamics.Comment: 11 pages and 7 figures, written using the AIP distribution for REVTeX 4, Version 4.1 of REVTeX; corresponding author (D.R.V.) email: [email protected]

Non-vanishing theorems for rank two vector bundles on threefolds

The paper investigates the non-vanishing of $H^1(E(n))$, where $E$ is a (normalized) rank two vector bundle over any smooth irreducible threefold $X$ of degree $d$ such that Pic(X) \cong \ZZ. If $\epsilon$ is the integer defined by the equality $\omega_X = O_X(\epsilon)$, and $\alpha$ is the least integer $t$ such that $H^0(E(t)) \ne 0$, then, for a non-stable $E$ ($\alpha \le 0$) the first cohomology module does not vanish at least between the endpoints $\frac{\epsilon-c_1}{2}$ and $-\alpha-c_1-1$. The paper also shows that there are other non-vanishing intervals, whose endpoints depend on $\alpha$ and also on the second Chern class $c_2$ of $E$. If $E$ is stable the first cohomology module does not vanish at least between the endpoints $\frac{\epsilon-c_1}{2}$ and $\alpha-2$. The paper considers also the case of a threefold $X$ with Pic(X) \ne \ZZ but Num(X) \cong \ZZ and gives similar non-vanishing results.Comment: 18 page

A model for the analysis of security policies in service function chains

Two emerging architectural paradigms, i.e., Software Defined Networking (SDN) and Network Function Virtualization (NFV), enable the deployment and management of Service Function Chains (SFCs). A SFC is an ordered sequence of abstract Service Functions (SFs), e.g., firewalls, VPN-gateways,traffic monitors, that packets have to traverse in the route from source to destination. While this appealing solution offers significant advantages in terms of flexibility, it also introduces new challenges such as the correct configuration and ordering of SFs in the chain to satisfy overall security requirements. This paper presents a formal model conceived to enable the verification of correct policy enforcements in SFCs. Software tools based on the model can then be designed to cope with unwanted network behaviors (e.g., security flaws) deriving from incorrect interactions of SFs in the same SFC

Molecules, surfaces, crystals: A quantum chemical quest from fundamentals to applications

My research focuses on applying fundamental laws governing the behavior of molecules and materials to predict their real-world performance. Using state-of-the-art quantum chemical approaches as my tool set, I computationally model a wide range of molecular and condensed-matter systems: explosives, pharmaceuticals, porous materials, catalysts, nanomaterials, polymers, soft-matter, films, membranes, surfaces, interfaces, layered materials; hybrid systems: molecules interacting with substrates; and, their properties: structural, energetic, vibrational, electronic, mechanical, adsorption, diffusion. Chemical processes such as reactivity and the change of properties after exposure to external agents (e.g. durability) can also be explored. The results of my investigations can contribute to speeding up, decreasing the cost, and increasing the robustness of the development cycle of new materials and materials-dependent products.https://digitalcommons.mtu.edu/techtalks/1006/thumbnail.jp

Spook Fest Style Guide

This style guide contains branding guidelines for Spook Fest, including logo design, logo use, color palette, and typography.https://digitalscholarship.unlv.edu/grc_380/1007/thumbnail.jp

La responsabilità dell’ente da reato nel sistema russo

Il saggio dà conto del sistema russo dell’illecito dell’ente da reato nella sola area amministrativo-punitiva e del relativo dibattito sulla ‘colpevolezza’. L’oggettiva severità di talune sanzioni, formalmente ‘amministrative’ ma sostanzialmente ‘penali’, lascia profilare una rilevante lesione delle essenziali garanzie sostanziali e processuali. Il saggio approfondisce anche il significato dei meccanismi di autoregolamentazione dell’ente diretti a prevenire la corruzione