1,720,983 research outputs found
Un'indagine sui luoghi urbani dimenticati: condizioni socioeconomiche nelle aree di origine abusiva a Roma
No full textL’articolo esplora il fenomeno dell'abusivismo edilizio a Roma, tracciandone le dinamiche storiche e sociali e analizzando le attuali condizioni di vita dei residenti. Tale fenomeno è stato spesso trattato politicamente come un’emergenza imprevista, piuttosto che come un problema sistemico e, con poche eccezioni, lo Stato la rinunciato a regolamentarlo. La prima parte dello studio ricostruisce lo sviluppo urbano della città, concentrandosi su aspetti non lineari e contraddittori della crescita abusiva. Nella seconda parte, viene presentata la metodologia impiegata per creare le prime mappe dell’abusivismo edilizio a Roma. Si conclude discutendo le attuali tendenze politiche ed elettorali e la necessità di politiche mirate per affrontare il fenomeno
Low-energy graceful exit in anisotropic string cosmology backgrounds
No full textAbstractWe discuss the possibility of a smooth transition from the pre- to the post-big bang regime, in the context of the lowest-order string effective action (without higher-derivative corrections), taking into account with a phenomenological model of source the repulsive gravitational effects due to the back-reaction of the quantum fluctuations outside the horizon. We determine a set of necessary conditions for a successful and realistic transition, and we find that such conditions can be satisfied (by an appropriate model of source), provided the background is higher-dimensional and anisotropic
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A comparison of HTB based channel-aware schedulers for 802.11 systems
No full textThe 802.11 commercial devices adopt a simple FIFO scheduler, which does not allow to isolate flows addressed to different destinations. This characteristic leads to the well-known performance anomaly of 802.11: when one or more STAs experiment poor radio channel conditions, they increase the time spent to transmit a single packet leading to an inefficient use of the shared medium. These phenomena have as a consequence the worsening of the performance of all the STAs sharing the wireless medium independently of their radio channel conditions. In this scenario, the paper proposes an architecture for a scheduling algorithm to implement in the AP for the downlink traffic, based on Hierarchical Token Bucket (HTB). The peculiarity of the proposed architecture is its ability to take into account, besides the transport service class required by the destination user, the channel quality experimented by the destination mobile STAtion (STA). Starting from this architecture two scheduling schemes are then proposed: the Wireless HTB (WHTB) and the Time-based WHTB (TWHTB). Both schemes are implemented in a prototype of AP. Hence, the performance of the proposed scheduling algorithms are experimentally evaluated and compared with those obtained with standard scheduling algorithm, which do not take into account information on channel quality. Finally, the paper presents a comparison in terms of implementation issues highlighted by the two proposed schemes, during the developing phase and the experimental analysis
Automatic IPSec Security Association Negotiation in Mobile-Oriented IPv6 Networks
No full textIntegrated mobility and security support is one of the most desirable feature for a network. Although IPv6 offers protocol which satisfies both these requirements, practical issues still exist which do not allow for a really integrated environment. Our contribution towards such integration is the development of a solution to automate the task of setting up the appropriate IPSec Security Associations each time a node connects to an IPv6 subnet. The result is mipsd, a user-space daemon which interacts with the IKE daemon running at the mobile host to allow the completely automated setup of SA towards the corresponding Security Gateway
The Wireless Hierarchical Token Bucket: a Channel Aware Scheduler for 802.11 Networks
No full textThe paper proposes air architecture for a scheduling algorithm, to be integrated in IEEE 802.11 Access Points (AP), able to take into account, besides the transport service class required by the destination user, the channel quality experimented by the destination mobile STAtion (STA). The relevance of this topic is due to the observation that when one or more STAs experiment poor radio channel conditions, they increase the time spent to transmit a single packet, due to the retransmission of corrupted frames and the adoption of a transmission techniques at lower bit rate, leading to an inefficient use of the shared medium. These phenomena have as a consequence the worsening of the performance of all the STAs sharing the wireless medium independently of their radio channel conditions. The adoption of a scheduling algorithm able to manage information on channel quality permits to reduce these effects, not penalizing the STAs experimenting good channel condition and, as a consequence, their experimented throughput. As a result, only the STAs in bad channel conditions experiment a reduction of throughput. A prototype of an AP equipment implementing the proposed architecture is then presented; it has been obtained modifying the Hierarchical Token Bucket (HTB) and has been indicated as Wireless Hierarchical Token Bucket (WHTB). The performance of the presented prototype are experimentally evaluated and compared with those obtained with standard scheduling algorithm, which do not take into account information on channel quality
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
MIPSD (Mobility-oriented IPSec Daemon): a Tool for Integrated Mobility and Security Support in the Ecumene Network
No full textThe IP protocol is stateless and connectionless, hence cannot guarantee a secure delivery of the information. IPSec offers stateful security introducing logical connections between couples of peers. The management of these IPSec Security Associations is often delegated to dynamic protocols, such as ISAKMP and IKE, because of the obvious scalability problem of a manual configuration approach. However, the address of each peer must be known in advance to the other one in order for the ISAKMP exchange to be completed successfully. This assumption cannot be always guaranteed, especially when mobility is taken into consideration. In such cases, a proper mechanism to retrieve the correspondent peer IPv6 address must be taken into account. The demo consists of an overview of the functionalities of the Ecumene Web Information System, developed in the groundwork of the Ecumene Project, focusing mainly on the enhancements developed (in the form of the MIPSD daemon) to allow automatic IPSec SA insaturation between hosts which wants to access the network and the appropriate Site Gateway
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