86,723 research outputs found
Herramientas para la conectividad IPv6 con múltiples proveedores
No full textLa presente Tesis propone una arquitectura para la provisión de una solución de multihoming escalable y de la exploración de distintos enfoques. La solución actualmente disponible en IPv4 para el soporte de multihoming basada en la inyección de rutas de sitio en el sistema global de rutas impone una carga que crece linealmente con el número de sitios multihomed, lo que limita su escalabilidad y las posibilidades de crecimiento. La presente Tesis plantea una solución alternativa que garantice la escalabilidad del sistema global de rutas basada en el uso de direcciones agregables por proveedor (PA). En una configuración basada en direcciones PA, un sitio multihomed obtiene tantos bloques de dirección como proveedores tiene lo que plantea las dificultades con los filtros de ingreso, con el iniciar una nueva comunicaciones después de un fallo y la preservación de comunicaciones ante la ocurrencia de un fallo. La presente Tesis Doctoral plantea una arquitectura para solventar estos problemas basada en el encaminamiento basado en dirección origen para proveer compatibilidad con los filtros de ingreso, y una nueva capa de identificación dentro de la capa IP para brindar las capacidades requeridas de tolerancia de fallos.
________________________________________________In this Thesis we propose an architecture for the provision of scalable IPv6 multihoming support. In the multihoming solution currently deployed in the IPv4 Internet, the multihomed site announces a route to its address blocks through all the providers using BGP. The result is that
multiple routes towards the multihomed site are available in the inter-domain routing system.
While this solution provides the fault tolerance and path selection features required to a
multihoming solution, it presents limited scalability, since each multihomed site contributes with
at least one routing table entry in the already oversized inter-domain routing tables.
Because the support of the multihoming solution currently deployed in the IPv4 Internet is
becoming challenging even for the current number of multihomed sites, this approach is deemed
unsuitable for the expected number of multihomed sites in the future IPv6 Internet, especially
when considering that the wide adoption of low-budget broadband access technologies such as
ADSL or CATV will enable multihoming in SOHO environments. As a consequence, an
alternative multihoming solution for IPv6 is needed. The requirements imposed to the new
solution essentially include all the benefits provided by the incumbent solution, i.e. fault tolerance
and traffic engineering capabilities, and also an enhanced scalability with respect to the number of
multi-homed sites and other relevant Internet parameters. In order to preserve routing system
scalability, aggressive route aggregation can be achieved through provider-based aggregation,
precluding the injection of routes associated with individual multi-homed end-sites. When
Provider Aggregatable (hereafter PA) addressing is used, multi-homed sites obtain one prefix per
each one of their providers. Consequently, as each provider will only announce its own prefix to
the rest of the Internet, a given provider will be used to reach the multihomed site only when the
destination addresses used belong to the prefix associated with the provider. So, in order to be
reachable through all of the providers of the site, each host within the multihomed site will have
to configure multiple addresses, one per provider.
Even if this setup guarantees the scalability of the multihoming solution, such multi-addressed
configuration is not without difficulties of its own when attempting to provide the additional
features mentioned above. In particular, this configuration presents the following problems:
- Incompatibility with ingress filtering techniques: The incompatibility is caused by the
lack of coordination between the IPv6 source address selection mechanism, performed by
the host, and the path selection mechanism, performed by the intra-site routing system.
As long as outgoing packets are routed through the provider that has delegated the prefix
contained in the source address, packets will flow freely; but when those packets are
routed through a different ISP, they will be discarded by the ingress filtering mechanism
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due to source address incompatibility. It must be noted that because of this issue, packets
may be discarded even in a scenario without failures.
- Difficulties when establishing new communications after an outage. The difficulties arise
because not all of the addresses available for a multihomed host are reachable, so in order
to be able to communicate, hosts need to properly discard unreachable addresses and
select those addresses that are reacahable. Current address selection mechanisms are
unable to cope with such situation.
- Difficulties when preserving established communications. In order to preserve
established communications through outages, the endpoints of the communication have to
adapt the addresses used during the lifetime of the communication according to the
available providers. Moreover, this address replacement has to be performed in a
transparent fashion with respect to transport and application layers, in order to actually
preserve the established communication. Current applications and transport layers, such
as TCP and UDP, identify the endpoints of a communication through the IP addresses of
the nodes involved, implying that the IP addresses selected at the communication
establishment time must remain invariant through the lifetime of the communication. But
as it has been presented earlier, once that an outage has occurred in one of the available
ISPs, the associated address becomes unreachable, so an alternative address has to be
used in order to convey packets to the multi-homed host. These two constraints impose
that after an outage, packets must carry a different address, corresponding to an available
ISP, but they have to be presented to transport and application layers as if they contained
the original address, in order to be recognized as belonging to the established
communication. Such approach requires additional mechanisms in both ends of the
communication in order to preserve a coherent mapping between the IP addresses
presented to the transport and application layers and those addresses actually contained in
the packets.
- Difficulties when providing traffic engineering capabilities. The usage of multiple
prefixes pre multihomed site imply that those traffic engineering techniques will no
longer apply, and alternative mechanisms that provide equivalent capabilities are
required.
In this Thesis we describe an architecture for the provision of multihoming in IPv6 that deals with
all the aforementioned concerns. The proposed IPv6 multihoming architecture introduces the
following components:
- An intra-site routing paradigm that takes into account the source address, so that source
hosts can determine through the selection of the source address, the exit path of the
packets. Such feature provides ingress filtering compatibility.
- An address selection mechanism that takes into account address reachability information
acquired through a trial and error procedure.
- A new Multihoming Sub-Layer within the IP layer that will perform the required
mapping between the addresses that are presented to the upper layer protocols and the
addresses that are actually used for exchanging packets in the network. Such layer allows
the usage of different addresses for exchanging packets during the lifetime of a
communication, while keeping unchanged the address presented to the upper layers,
preserving the established communication.
- A mechanism for the configuration of the policy table defined in the default address
selection procedure, for the provision of traffic engineering capabilities.
A detailed presentation of the aforementioned mechanisms is preceded by an exhaustive
analysis of the solution space that justifies the selected approach
Variations on the Author
No full text“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
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Effectivness of RAPD primer polymorphysm in the evaluation of genetic distances in Vitis vinifera L.. Proc. of the 4th Seminar: “Italo-Albanian cooperation for enhancement of the plant biodiversity”
No full textAlso By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
John F. Kennedy telegram to Roosevelt
No full textJersey Homesteads (later the Borough of Roosevelt) was established in the 1930s as an agro-industrial cooperative community. It was established specifically for urban Jewish garment workers, many of whom had emigrated from Europe. President John F. Kennedy sent a telegram to the citizens of Roosevelt, New Jersey, apologizing for not being able to attend the memorial dedication in honor of former President Franklin Delano Roosevelt. (Jersey Homesteads became Roosevelt in 1945 in honor of the president.) President Kennedy expressed his gratitude to the people of Roosevelt for constructing the memorial, and commented that it will serve as a constant reminder of Roosevelt's good works
FLUDARABINE AND CYCLOPHOSPHAMIDE FOR THE TREATMENT OF PATIENTS WITH INDOLENT NON-FOLLICULAR (INFL) B-CELL NON-HODGKIN'S LYMPHOMAS. PRELIMINARY RESULTS OF A PHASE II TRIAL OF THE 'GRUPPO ITALIANO PER LO STUDIO DEI LINFOMI (GISL)
No full textIntroduction: INFL comprises a rather heterogeneous subgroup of lymphomas,including small lymphocytic lymphoma (SLL), immunocytoma (IC) and marginalzone lymphomas (MZL). In April 2002, the GISL started a phase II trial to verifythe efficacy of fludarabine and cyclophosphamide (Flu–Cy) combination in this subsetof NHL, in terms of response, survival and toxicity.Patients and methods: Patients should have a diagnosis of SLL, IC, MZL or CD5negative mature B-cell leukemia (MBCL), supported by morphologic, phenotypicand molecular data; patients should also be untreated for lymphoma and have activedisease defined by the presence of anemia, thrombocytopenia, bulky disease, rapidlyincreasing lymphocytosis or enlarging masses. Treatment consisted of fludarabine25 mg/m2 i.v. day 1–3 and cyclophosphamide 250 mg/m2 i.v. days 1–3, to berepeated every 28 days for six cycles; an intermediate evaluation of response afterthree cycles was planned and an adequate anti-infective prophylaxis was mandatory.Results: As of March 2004, 44 patients were registered into the trial; one patientwas excluded from the study due to incorrect histology. Median age was 63 years(range 39–75), M/F ratio was 1.9. The diagnosis was SLL in 11 patients, IC in 7,MZL in 19 and MBCL in 5. All patients had stage IV disease. Anemia was presentin 32%, elevated b2 microglobulin in 56%, abnormal LDH in 32%. At the time ofthe present analysis, 24 patients completed the treatment program with 13 CR (52%)and 11 PRs (44%). Three patients died during treatment, one after the second cycledue to erosive pulmonary aspergillosis, the others due to bone marrow aplasiaoccurred after the 4th and 5th cycle, respectively. Overall, grade III or IV hematologicaltoxicity was observed in 44% of the patients. After a median follow-up of9 months, OS was 81%.Conclusion: The preliminary results of our study demonstrate that the Flu–Cycombination is effective in the treatment of patients with INFL but has also shown arelevant toxicity profile suggesting the need for extensive antimicrobial prophylaxi
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
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