2,359 research outputs found
Replicated computational results (RCR) Report for "Fast random integer generation in an interval"
No full textThe article "Fast Random Integer Generation in an Interval" by Lemire (2018) addressed the problem of reducing the cost of machine instructions needed for the random generation of integer values in a generic interval [0,s). The approach taken by the author is the one of exploiting the rejection method (Neumann 1951) to build an algorithm that almost eliminates the need for performing integer division operations-the algorithm still exploits divisions by powers of two, implemented in the form of cheap shift operations. In more details, the likelihood of not requiring an integer division in the proposed algorithm is 2 L -s/2 L , where L denotes the number of bits used to represent integer values. The author also presents a comparative experimental study where the new algorithm, and its implementation for x86 processors, are compared with solutions offered by common software libraries for different programming languages
Supporting function calls within PELCR
No full textIn [M. Pedicini and F. Quaglia. A parallel implementation for optimal lambda-calculus reduction PPDP '00: Proceedings of the 2nd ACM SIGPLAN international conference on Principles and practice of declarative programming, pages 3-14, ACM, 2000, M. Pedicini and F. Quaglia. PELCR: Parallel environment for optimal lambda-calculus reduction. CoRR, cs.LO/0407055, accepted for publication on TOCL, ACM, 2005], PELCR has been introduced as an implementation derived from the Geometry of Interaction in order to perform virtual reduction on parallel/distributed computing systems. In this paper we provide an extension of PELCR with computational effects based on directed virtual reduction [V. Danos, M. Pedicini, and L. Regnier. Directed virtual reductions. In M. Bezem D. van Dalen, editor, LNCS 1258, pages 76-88. EACSL, Springer Verlag, 1997], namely a restriction of virtual reduction [V. Danos and L. Regnier. Local and asynchronous beta-reduction (an analysis of Girard's EX-formula). LICS, pages 296-306. IEEE Computer Society Press, 1993], which is a particular way to compute the Geometry of Interaction [J.-Y. Girard. Geometry of interaction 1: Interpretation of system F. In R. Ferro, et al. editors Logic Colloquium '88, pages 221-260. North-Holland, 1989] in analogy with Lamping's optimal reduction [J. Lamping. An algorithm for optimal lambda calculus reduction. In Proc. of 17th Annual ACM Symposium on Principles of Programming Languages. ACM, San Francisco, California, pages 16-30, 1990]. Moreover, the proposed solution preserves scalability of the parallelism arising from local and asynchronous reduction as studied in [M. Pedicini and F. Quaglia. PELCR: Parallel environment for optimal lambda-calculus reduction. CoRR, cs.LO/0407055, accepted for publication on TOCL, ACM, 2005]. © 2006 Elsevier B.V. All rights reserved
A low-overhead constant-time Lowest-Timestamp-First CPU scheduler for high-performance optimistic simulation platforms
No full textAn approach to high-performance discrete event simulation consists of exploiting parallelization techniques. These rely on partitioning the simulation model into multiple, interacting simulation objects, also known as Logical Processes (LPs), which concurrently execute events on different CPUs and/or multiple CPU-cores. However, despite the tendency towards high degree of hardware parallelism, for relatively large models, multi-programming schemes are still needed in order to share a single CPU-core across multiple LPs. Consequently, priority management and CPU-scheduling remain central issues for the effectiveness of any parallel simulation environment. This article focuses on the optimistic approach to parallelism, which is based on speculative processing and maintains event-causality across concurrent LPs via rollback techniques. Specifically, the article presents a low-overhead constant-time implementation of the well known Lowest-Timestamp-First algorithm for the identification of the next LP to be CPU-dispatched. This proposal is suited for contexts where the optimistic simulation system conforms to the best-practice of keeping separate event lists for the hosted LPs. The implementation has been integrated in the open source ROOT-Sim (ROme OpTimistic Simulator) package. The effectiveness of the presented proposal is assessed via an extended performance study, carried out by relying on the game of life as the test-bed application. © 2015 Elsevier B.V. All rights reserved
“Contourner le vide: écriture et judéité(s) après la Shoah”, dir. F. DAINESE et E. QUAGLIA, Firenze, Giuntina, 2020, 123 pp.
No full textRecensione a volume miscellaneo dedicato alle ambivalenti tracce della judéité in vari autori di lingua francese del Novecento
Editorial to the Special Issue on the Principles of Advanced Discrete Simulation (PADS)
No full textWelcome to this special issue of ACM TOMACS on the Principles of Advanced Discrete Simulation (PADS), which is based on selected articles from the 2018 ACM SIGSIM-PADS Conference. This is the flagship conference of the ACM's Special Interest Group on Simulation and Modeling (SIGSIM), whose 2018 edition was held at the University of Rome La Sapienza, on May 23–25, 2018. This special issue is edited by Georgios Theodoropoulos, Alessandro Pellegrini, and Francesco Quaglia, who served as the conference program and general chairs, and were responsible for the proceedings of the conference.
The articles appearing in this special issue have been selected also thanks to the help of Prof. Adelinde Uhrmacher, who acted as the Editor in Chief of ACM TOMACS until August 2019. The outcome of the selection process identified seven articles, top ranked in the review process of PADS 2018, as possible candidates for this special issue. The authors of three of them have been able to meet the deadlines for submitting the substantially extended versions of the original conference articles, while the others were not able to produce sufficiently new results on time to meet the special issue schedule. The submission process for this special issue started in November 2018, and the final decisions for all the involved articles have been made by November 2019, with a very minimal delay with respect to the originally planned schedule. The articles submitted to this special issue and having the organizers of PADS 2018 as authors have been handled directly by Prof. Adelinde Uhrmacher. As an additional mean for keeping the quality of the articles accepted in this special issue at excellent levels, the invited authors had to provide an extension plan of their original conference articles, the adequacy of which has been early assessed by the Guest Editors and by the TOMACS Editor in Chief. Also, a minimum of three reviewers peer reviewed the submitted articles
Chromatographic indices determined on an immobilized artificial membrane (IAM) column as descriptors of lipophilic and polar interactions of 4-phenyldihydropyridine calcium channel blockers with biomembranes
No full textA set of nine 4-phenyldihydropyridine (DHP) calcium-channel blockers including both ionizable and unionizable molecules has been examined. The chromatographic parameters log k' have been determined by HPLC on an immobilized artificial membrane (IAM) column which is a solid-phase model of fluid membranes. The influence of different percentages of organic modifier and ionic strength of the eluent on the chromatographic behaviour has been studied in order to identify the best experimental conditions modelling the in vivo interaction with phospholipids. As different ranking orders can occur under different experimental conditions, log k' values extrapolated to 100% aqueous phase (log kwIAM) have been determined. Moreover, n-octanol/buffer partition data at pH 7.4 and 12.5 (log D7.4 and log P) and chromatographic data on a hydrocarbon HPLC stationary phase (log kwODS) have been measured. Comparative studies between the experimental data, obtained for the different systems, have shown that the IAM-derived scale is distinct from the one obtained by 'conventional' lipophilic indices, because of the particular behaviour of the basic DHPs. Moreover, only IAM parameters are good descriptors of the strong interactions of the basic DHPs with biomembranes. In fact, the chromatography of neutral compounds is mainly lipophilicity dependent while a 'dual' mechanism, partition and ion-exchange, operates for basic analogues. In this case the lipophilic component is insensitive to the protonation of the basic function. Finally, receptor binding values from rat cortical brain preparations successfully correlate with log kwIAM. Hence, the biomembrane affinity of DHPs appears to be a critical factor for access to their receptor sit
Filogenesi di alcune popolazioni di cinghiali (Sus scrofa) in Italia
No full textFilogenesi di alcune popolazioni di cinghiali (Sus Scrofa) in Italia
Laura Lattuada, Federica Quaglia, Renato Bacchetta, Michele Polli
La consistenza e l’attuale diffusione del cinghiale (Sus Scrofa) in Italia sono il risultato di una vera e propria esplosione demografica avvenuta, come in altri paesi europei, a partire dal secondo dopoguerra; un ruolo fondamentale in questo processo è stato svolto anche dall’importazione di animali da alcuni paesi dell’Europa centro-orientale che hanno potuto incrociarsi con nuclei di cinghiali autoctoni e con locali popolazioni di maiali viventi in regime di semilibertà. Lo scopo di questo lavoro è quello di analizzare le relazioni filogenetiche tra diverse popolazioni di cinghiali italiane e verificare l’esistenza di eventuali ibridazioni con i maiali domestici. Sono state così sequenziate 466 bp, dalla posizione 15619 alla posizione 16085 rispetto alla sequenza di riferimento GenBank AJ002189 del DNA mitocondriale, di 59 esemplari provenienti da tre regioni italiane: Lombardia (provincia di Bergamo), Toscana (provincia di Arezzo) ed Emilia Romagna (provincia di Parma). Le analisi hanno individuato13 SNPs definendo 9 differenti aplotipi che sono stati confrontati con 53 sequenze di maiali e cinghiali europei ed asiatici. Le analisi sono state condotte utilizzando i software PHYLIP e TREEPUZZLE per la costruzione degli alberi filogenetici con il metodo Neighbour-Joining e Maximum Likelihood; come outgroup è stato considerato il facocero (Phacochoerus aethiopicus). I risultati delle analisi filogenetiche indicano che le 3 popolazioni studiate, posizionandosi principalmente nel clade che include linee selvatiche e razze domestiche europee, mostrano chiari segni di introgressione dei geni alloctoni. Solo gli esemplari della Maremma Toscana, presenti in GeneBank, sembrerebbero presentare una linea mitocondriale esclusiva dei cinghiali italiani
La resistenza negli artropodi che frequentano gli ambienti urbani: problematiche e prospettive
No full textNote eco-etologiche sulla Philippia oleae (O.G. COSTA) (Rhynchota, Coccoidea), Lecaniide infeudato sull'olivo in Toscana
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