University of Cagliari

About: University of Cagliari is a education organization based out in Cagliari, Italy. It is known for research contribution in the topics: Population & Dopamine. The organization has 11029 authors who have published 29046 publications receiving 771023 citations. The organization is also known as: Università degli Studi di Cagliari & Universita degli Studi di Cagliari.

Entry Barriers in Retail Trade

Abstract: The 1998 reform of the Italian retail trade sector delegated the regulation of entry of large stores to the regional governments. We use the local variation in regulation to determine the eects of entry barriers on sectoral performance. We address the endogeneity of entry barriers through local xed eects and using political variables as instruments. We also control for dierences in trends and for area-wide shocks. We nd that entry barriers are associated with substantially larger prot margins and lower productivity of incumbent rms. Liberalizing entry has a positive eect on investment in ICT, increases employment and compresses labor costs in large shops. In areas with more stringent entry regulation, lower productivity coupled with larger margins results in higher consumer prices. JEL classication: L5, L11, L81

Is Feature Selection Secure against Training Data Poisoning

Abstract: Learning in adversarial settings is becoming an important task for application domains where attackers may inject malicious data into the training set to subvert normal operation of data-driven technologies. Feature selection has been widely used in machine learning for security applications to improve generalization and computational efficiency, although it is not clear whether its use may be beneficial or even counterproductive when training data are poisoned by intelligent attackers. In this work, we shed light on this issue by providing a framework to investigate the robustness of popular feature selection methods, including LASSO, ridge regression and the elastic net. Our results on malware detection show that feature selection methods can be significantly compromised under attack (we can reduce LASSO to almost random choices of feature sets by careful insertion of less than 5% poisoned training samples), highlighting the need for specific countermeasures.

Crucial Role of α4 and α6 Nicotinic Acetylcholine Receptor Subunits from Ventral Tegmental Area in Systemic Nicotine Self-Administration

Abstract: The identification of the molecular mechanisms involved in nicotine addiction and its cognitive consequences is a worldwide priority for public health. Novel in vivo paradigms were developed to match this aim. Although the β2 subunit of the neuronal nicotinic acetylcholine receptor (nAChR) has been shown to play a crucial role in mediating the reinforcement properties of nicotine, little is known about the contribution of the different α subunit partners of β2 (i.e., α4 and α6), the homo-pentameric α7, and the brain areas other than the ventral tegmental area (VTA) involved in nicotine reinforcement. In this study, nicotine (8.7–52.6 μg free base/kg/inf) self-administration was investigated with drug-naive mice deleted (KO) for the β2, α4, α6 and α7 subunit genes, their wild-type (WT) controls, and KO mice in which the corresponding nAChR subunit was selectively re-expressed using a lentiviral vector (VEC mice). We show that WT mice, β2-VEC mice with the β2 subunit re-expressed exclusively in the VTA, α4-VEC mice with selective α4 re-expression in the VTA, α6-VEC mice with selective α6 re-expression in the VTA, and α7-KO mice promptly self-administer nicotine intravenously, whereas β2-KO, β2-VEC in the substantia nigra, α4-KO and α6-KO mice do not respond to nicotine. We thus define the necessary and sufficient role of α4β2- and α6β2-subunit containing nicotinic receptors (α4β2*- and α6β2*-nAChRs), but not α7*-nAChRs, present in cell bodies of the VTA, and their axons, for systemic nicotine reinforcement in drug-naive mice.

Spatial spillovers and innovation activity in European regions

Abstract: This paper explores the spatial distribution of innovative activity and the role of technological spillovers in the process of knowledge creation and diffusion across 175 regions of 17 countries in Europe (the 15 members of the pre-2004 European Union plus Switzerland and Norway). The analysis is based on a databank set up by CRENoS on regional patenting at the European Patent Office, spanning from 1978 to 2001 and classified by ISIC sectors. The first step is an exploratory spatial data analysis of the dissemination of innovative activity in Europe . The goal of the rest of the paper is to analyse to what extent externalities that cross regional boundaries can explain the spatial association process detected in the distribution of innovative activity in the European regions. The framework given by the knowledge production function together with the use of spatial econometrics techniques allow us to look for insights on the mechanics of knowledge interdependences across regions, which are shown to exist. Empirical results point to the relevance of internal regional factors (R&D expenditure and agglomeration economies). Moreover, the production of knowledge appears to be also affected by spatial spillovers due to innovative activity (both patenting and R&D) performed in other regions. Additional results show that spillovers are mostly constrained by national borders within less than 250 kilometres, and that technological similarity between regions also matters.