An alternative B cell development program

Two major types of B cells, the antibody-producing cells of the immune system, are classically distinguished in the spleen: marginal zone (MZ) and follicular (FO). In addition, FO B cells are subdivided into FO I and FO II cells, based on the amount of surface IgM. MZ B cells, which surround the splenic follicles, rapidly produce IgM in response to blood-borne pathogens without T cell help, while T cell-dependent production of high affinity, isotype-switched antibodies is ascribed to FO I cells. The significance of FO II cells and the mechanism underlying B cell fate choices are unclear. We showed that FO II cells express more Sca1 than FO I cells and originate from a distinct B cell development program, marked by high expression of Sca1. MZ B cells can derive from the “canonical” Sca1lo pathways, as well as from the Sca1hi program, although the Sca1hi program shows a stronger MZ bias than the Sca1lo program, and extensive phenotypic plasticity exists between MZ and FO II, but not between MZ and FO I cells. The Sca1hi program is induced by hematopoietic stress and generates B cells with an Igλ-enriched repertoire. In aged mice, the canonical B cell development pathway is impaired, while the Sca1hi program is increased. Furthermore, we showed that a population of unknown function, defined as Lin-c-kit+Sca1+ (LSK-), contains early lymphoid precursors, with primarily B cell potential in vivo. Our data suggest that LSK- cells may represent a distinct precursor for the Sca1hi program in the bone marrow.

Design and Performance Evaluation of Network-on-Chip Communication Protocols and Architectures

The scale down of transistor technology allows microelectronics manufacturers such as Intel and IBM to build always more sophisticated systems on a single microchip. The classical interconnection solutions based on shared buses or direct connections between the modules of the chip are becoming obsolete as they struggle to sustain the increasing tight bandwidth and latency constraints that these systems demand. The most promising solution for the future chip interconnects are the Networks on Chip (NoC). NoCs are network composed by routers and channels used to inter- connect the different components installed on the single microchip. Examples of advanced processors based on NoC interconnects are the IBM Cell processor, composed by eight CPUs that is installed on the Sony Playstation III and the Intel Teraflops pro ject composed by 80 independent (simple) microprocessors. On chip integration is becoming popular not only in the Chip Multi Processor (CMP) research area but also in the wider and more heterogeneous world of Systems on Chip (SoC). SoC comprehend all the electronic devices that surround us such as cell-phones, smart-phones, house embedded systems, automotive systems, set-top boxes etc... SoC manufacturers such as ST Microelectronics , Samsung, Philips and also Universities such as Bologna University, M.I.T., Berkeley and more are all proposing proprietary frameworks based on NoC interconnects. These frameworks help engineers in the switch of design methodology and speed up the development of new NoC-based systems on chip. In this Thesis we propose an introduction of CMP and SoC interconnection networks. Then focusing on SoC systems we propose: • a detailed analysis based on simulation of the Spidergon NoC, a ST Microelectronics solution for SoC interconnects. The Spidergon NoC differs from many classical solutions inherited from the parallel computing world. Here we propose a detailed analysis of this NoC topology and routing algorithms. Furthermore we propose aEqualized a new routing algorithm designed to optimize the use of the resources of the network while also increasing its performance; • a methodology flow based on modified publicly available tools that combined can be used to design, model and analyze any kind of System on Chip; • a detailed analysis of a ST Microelectronics-proprietary transport-level protocol that the author of this Thesis helped developing; • a simulation-based comprehensive comparison of different network interface designs proposed by the author and the researchers at AST lab, in order to integrate shared-memory and message-passing based components on a single System on Chip; • a powerful and flexible solution to address the time closure exception issue in the design of synchronous Networks on Chip. Our solution is based on relay stations repeaters and allows to reduce the power and area demands of NoC interconnects while also reducing its buffer needs; • a solution to simplify the design of the NoC by also increasing their performance and reducing their power and area consumption. We propose to replace complex and slow virtual channel-based routers with multiple and flexible small Multi Plane ones. This solution allows us to reduce the area and power dissipation of any NoC while also increasing its performance especially when the resources are reduced. This Thesis has been written in collaboration with the Advanced System Technology laboratory in Grenoble France, and the Computer Science Department at Columbia University in the city of New York.

L(ocus) d(atos) d(ecreto) d(ecurionum): La concessione di spazi pubblici nelle comunita' cittadine dell'italia romana

La tesi riguarda la concessione di spazi di proprietà pubblica a privati, intesi come singole persone o enti, quali ad esempio i collegi, da parte delle autorità cittadine. Le fonti a disposizione per indagare tale pratica burocratica sono quasi totalmente di natura epigrafica, per lo più attestanti l’espressione locus datus decreto decurionum, variamente abbreviata, o formule similari. Questo aspetto della vita civica è stata cursoriamente oggetto di studio in diversi contributi, ma si tratta di articoli che circoscrivono il tema, analizzandolo in relazione a ristrette aree geografiche, oppure considerandone determinati aspetti (ad esempio l’ambito sacro o quello funerario). Si è perciò ritenuto utile proseguire questa linea di ricerca affrontando uno studio di più ampio raggio, che comprenda la documentazione epigrafica dell’intero territorio italico (costituito dalle undici regioni augustee ad esclusione di Roma), per tutte le tipologie testuali (iscrizioni sacre, funerarie, onorarie, su opera pubblica, exempla decreti), allo scopo di formulare osservazioni più precise e puntuali sulla procedura burocratica in esame, pur con tutti i limiti noti a chi affronti questo genere di indagine. Tra le conclusioni raggiunte, è emerso come durante il I-II sec. d.C. vi fosse la tendenza a concedere, sporadicamente, dei loca sepulturae extraurbani a membri delle famiglie delle élites cittadine, anche donne e fanciulli, mentre il foro e le altre aree pubbliche interne alla città erano soprattutto utilizzate direttamente dai decurioni per l’elevazione di dediche e statue. Nel corso del II sec. d.C., con massima diffusione nell’età antonina e poi in quella severiana, prese invece piede l’uso privato a scopo onorario degli spazi pubblici siti all’interno delle città, ovvero in aree prima pressoché precluse all’intervento di singoli cittadini: familiari e liberti, collegi e altri organismi commissionavano statue dedicate prevalentemente agli amministratori locali, magistrati cittadini spesso divenuti anche cavalieri.

The dynamics of early-type galaxies as a tool to understand their hot coronae and their IMF

Dynamical models of galaxies are a powerful tool to study and understand several astrophysical problems related to galaxy formation and evolution. This thesis is focussed on a particular type of dynamical models, that are widely used in literature, and are based on the solution of the Jeans equations. By means of a numerical Jeans solver code, developed on purpose and able to build state-of-the-art advanced axisymmetric galaxy models, two of the main currently investigated issues in the field of research of early-type galaxies (ETGs) are addressed. The first topic concerns the hot and X-ray emitting gaseous coronae that surround ETGs. The main goal is to explain why flat and rotating galaxies generally exhibit haloes with lower gas temperatures and luminosities with respect to rounder and velocity dispersion supported systems. The second astrophysical problem addressed concerns instead the stellar initial mass function (IMF) of ETGs. Nowadays, this is a very controversial issue due to a growing number of works on ETGs, based on different and independent techniques, that show evidences of a systematic variation of the IMF normalization as a function of galaxy velocity dispersion or mass. These studies are changing the previous opinion that the IMF of ETGs was the same as that of spiral galaxies, and hence universal throughout the whole large family of galaxies.