Papers by Giulio Colavolpe
The increasing prevalence of antibiotic-resistant bacteria has become a notorious threat to human... more The increasing prevalence of antibiotic-resistant bacteria has become a notorious threat to human health. Bacteria become resistant through resistance genes that can move between cells using horizontal gene transfer. Antibiotics are naturally produced by microorganisms in the environment and therefore bacterial communities maintain a large collection of resistance genes (the resistome). The diversity and mobility of the environmental resistome is however not well studied and further research into these issues is warranted. The aim of this project is to explore the environmental resistome and to characterize the abundance of known resistance genes in the environment, using metagenomic data. We collected 98 gigabytes of publicly available data from "The Community Database for Metagenomic Data" CAMERA, including more than 650 study sites around the world. Based on this data, we identified several common antibiotic resistance genes families spread in different environments, where the beta-lactamase TEM was the most abundant (having 41.7 % occurrence between 347 sites). We also compared the sites with clustering, and found that the resistome is highly variable. However, similarities were found also in geographically close sites, and between sites from similar environments. For instance, environments contaminated with antibiotics showed similarities in their resistome abundance. Additionally, we also clustered the resistome, observing groups of antibiotic resistance genes with similar abundance patterns between the sites. Several of these groups could be associated with genetically linked co-resistance through known horizontally transferred elements. We conclude that metagenomics is a powerful tool for identifying antibiotic resistance genes in uncultured bacteria.
John Wiley & Sons, Ltd eBooks, Mar 27, 2013
John Wiley & Sons, Ltd eBooks, Mar 27, 2013
John Wiley & Sons, Ltd eBooks, Mar 27, 2013
2015 IEEE 16th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), 2015
We consider the rates achievable by a user in a multibeam satellite system for unicast applicatio... more We consider the rates achievable by a user in a multibeam satellite system for unicast applications, and propose alternatives to the conventional single-user symbol-by-symbol detection applied at user terminals. Single-user detection is known to suffer from strong degradation when the terminal is located near the edge of the coverage area of a beam, and when aggressive frequency reuse is adopted. For this reason, we consider multiuser detection, and take into account the strongest interfering signal. We also analyze two additional transmission strategies requiring modifications at medium access control layer. We describe an information-theoretic framework to compare the different strategies by computing the information rate of the user in the reference beam. Furthermore, we analyze the performance of coded schemes that could approach the information-theoretic limits. We show that classical codes from the DVB-S2(X) standard are not suitable when multiuser detection is adopted, and we propose two ways to improve the performance, based on the redesign of the code and of the bit mapping.
IEEE Transactions on Communications
Lecture Notes in Computer Science, 2004
In this paper we describe a method, based on a genetic algorithm, for generating good (in terms o... more In this paper we describe a method, based on a genetic algorithm, for generating good (in terms of minimum distance) linear block error-correcting codes. Preliminary experimental results indicate that the method can be very effective, especially in terms of fast generation of good sub-optimal codes.
International Symposium onInformation Theory, 2004. ISIT 2004. Proceedings., 2004
The subject of this paper is the asymptotic optimality of finite-memory detection for transmissio... more The subject of this paper is the asymptotic optimality of finite-memory detection for transmission over a channel characterized by a single multiplicative time-invariant stochastic parameter (e.g., block frequency non-selective fading). It is known that any finite-memory detection algorithm, either trellisbased or graph-based, is characterized by a single basic metric. We present a theorem which proves that this metric tends, asymptotically, to that of a receiver with perfect channel state information.
IFIP International Federation for Information Processing, 2005
In high-speed optical transmission systems, one of the most challenging impairments is represente... more In high-speed optical transmission systems, one of the most challenging impairments is represented by the signal distortions produced by polarization-mode dispersion (PMD). In this paper, we analyze the limits of electronic compensation schemes, in the form of maximum-likelihood sequence detection receivers. With a constraint on the front-end processing after photo-detection, we compute the signal statistics necessary to implement this strategy. The receiver adaptivity is also discussed. The relevant performance is analyzed by means of computer simulations and accurate analytical performance bounds, and compared with the performance of all-optical compensators and decision-feedback equalizers. A significant performance loss with respect to optical compensation is observed for large values of the differential group delay (DGD) showing that, after the non reversible transformation operated by the photo-detector, it is not possible to effectively cope with the PMD-induced impairments.
Seventh International Symposium on Signal Processing and Its Applications, 2003. Proceedings., 2003
In this paper, we propose linear predictive receivers for phaseuncertain channels. These receiver... more In this paper, we propose linear predictive receivers for phaseuncertain channels. These receivers are attractive from a conceptual viewpoint because they generalize previous solutions based on noncoherent sequence detection. On the practical side, the proposed algorithms lend themselves to the implementation of adaptive receivers capable of copying with possible time variations of the statistics of the underlying phase model.
ABSTRACT Conference code: 85176, Export Date: 25 July 2012, Source: Scopus, Language of Original ... more ABSTRACT Conference code: 85176, Export Date: 25 July 2012, Source: Scopus, Language of Original Document: English, Correspondence Address: Razzano, E.; Carlo Gavazzi Space S.p.A., Via Nomentana 60, Roma, Italy; email: erazzano@cgspace.it, References: Scorzolini, A., De Perini, V., Razzano, E., Simionato, P., (2010) Satellite Based AIS for Maritime Safety, , Tolouse Space Show France;
2009 IEEE International Symposium on Information Theory, 2009
... Marco Secondini*, Dario Fertonani*, Giulio Colavolpe**, and Enrico Forestieri* *Scuola Superi... more ... Marco Secondini*, Dario Fertonani*, Giulio Colavolpe**, and Enrico Forestieri* *Scuola Superiore Sant'Anna, Pisa - Italy ... is equal (or proportional) to the conditional pdf p(yla == a) [1], [2]. In the following, only systems that can be described as a finite-state machine (FSM) [2] are ...
GLOBECOM '05. IEEE Global Telecommunications Conference, 2005., 2005
In this paper, we derive low-complexity MAP symbol detection algorithms for continuous phase modu... more In this paper, we derive low-complexity MAP symbol detection algorithms for continuous phase modulations (CPMs). To obtain this result, the well-known problem of a transmission over an additive white Gaussian noise (AWGN) channel affected by known intersymbol interference (ISI) is first considered. We show that the maximum a posteriori (MAP) symbol detection strategy, usually implemented by using the Forney observation
Euromicro Symposium on Digital System Design, 2004. DSD 2004., 2004
This paper presents a 2048 bit, rate 1/2 soft decision decoder for a new class of codes known as ... more This paper presents a 2048 bit, rate 1/2 soft decision decoder for a new class of codes known as turbo Gallager codes. The decoder can support up to 1 Gbit/s code rate and performs up to 48 decoding iteration ensuring at the same time high throughput and good coding gain. In order to evaluate the performance and the gate complexity
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Papers by Giulio Colavolpe