24 research outputs found
Cost-aware caching: optimizing cache provisioning and object placement in ICN
Caching is frequently used by Internet Service Providers as a viable
technique to reduce the latency perceived by end users, while jointly
offloading network traffic. While the cache hit-ratio is generally considered
in the literature as the dominant performance metric for such type of systems,
in this paper we argue that a critical missing piece has so far been neglected.
Adopting a radically different perspective, in this paper we explicitly account
for the cost of content retrieval, i.e. the cost associated to the external
bandwidth needed by an ISP to retrieve the contents requested by its customers.
Interestingly, we discover that classical cache provisioning techniques that
maximize cache efficiency (i.e., the hit-ratio), lead to suboptimal solutions
with higher overall cost. To show this mismatch, we propose two optimization
models that either minimize the overall costs or maximize the hit-ratio,
jointly providing cache sizing, object placement and path selection. We
formulate a polynomial-time greedy algorithm to solve the two problems and
analytically prove its optimality. We provide numerical results and show that
significant cost savings are attainable via a cost-aware design
Distribution efficace des contenus dans les réseaux : partage de ressources sans fil, planification et sécurité
In recent years, the amount of traffic requests that Internet users generate on a daily basis has increased exponentially, mostly due to the worldwide success of video streaming services, such as Netflix and YouTube. While Content-Delivery Networks (CDNs) are the de-facto standard used nowadays to serve the ever increasing users’ demands, the scientific community has formulated proposals known under the name of Content-Centric Networks (CCN) to change the network protocol stack in order to turn the network into a content distribution infrastructure. In this context this Ph.D. thesis studies efficient techniques to foster content distribution taking into account three complementary problems:1) We consider the scenario of a wireless heterogeneous network, and we formulate a novel mechanism to motivate wireless access point owners to lease their unexploited bandwidth and cache storage, in exchange for an economic incentive.2) We study the centralized network planning problem and (I) we analyze the migration to CCN; (II) we compare the performance bounds for a CDN with those of a CCN, and (III) we take into account a virtualized CDN and study the stochastic planning problem for one such architecture.3) We investigate the security properties on access control and trackability and formulate ConfTrack-CCN: a CCN extension to enforce confidentiality, trackability and access policy evolution in the presence of distributed caches.Au cours de ces dernières années, la quantité de trafic que les utilisateurs Internet produisent sur une base quotidienne a augmenté de façon exponentielle, principalement en raison du succès des services de streaming vidéo, tels que Netflix et YouTube. Alors que les réseaux de diffusion de contenu (Content-Delivery Networks, CDN) sont la technique standard utilisée actuellement pour servir les demandes des utilisateurs, la communauté scientifique a formulé des propositions connues sous le nom de Content-Centric Networks (CCN) pour changer la pile de protocoles réseau afin de transformer Internet en une infrastructure de distribution de contenu. Dans ce contexte, cette thèse de doctorat étudie des techniques efficaces pour la distribution de contenu numérique en tenant compte de trois problèmes complémentaires : 1) Nous considérons le scénario d’un réseau hétérogène sans fil, et nous formulons un mécanisme pour motiver les propriétaires des points d’accès à partager leur capacité WiFi et stockage cache inutilisés, en échange d’une contribution économique.2) Nous étudions le problème centralisé de planification du réseau en présence de caches distribuées et (I) nous analysons la migration optimale du réseau à CCN; (II) nous comparons les bornes de performance d’un réseau CDN avec ceux d’un CCN, et (III) nous considérons un réseau CDN virtualisé et étudions le problème stochastique de planification d’une telle infrastructure.3) Nous considérons les implications de sécurité sur le contrôle d’accès et la traçabilité, et nous formulons ConfTrack-CCN, une extension deCCN utilisée pour garantir la confidentialité, traçabilité et l’évolution de la politique d’accès, en présence de caches distribuées
A criança como protagonista na resolução de problemas no entorno escolar / The child as protagonist in solving problems in the school environment
O presente trabalho apresenta a forma como o ColĂ©gio Marista de CriciĂşma resolveu um problema relacionado ao trânsito com a participação efetiva das crianças em assembleia. A utilização da prática da Pedagogia da Escuta foi imprescindĂvel para a realização dos encontros. O artigo descreve a atitude de quebra de paradigmas e desenvolvimento da capacidade de ouvir e encaminhar processos, de ouvir o nĂŁo dito, buscar o inaudĂvel, ver o invisĂvel, de fazer boas perguntas e buscar muitos outros questionamentos que nĂŁo haviam sido pensados. O texto está embasado no diálogo entre professor e aluno, proposto por Freire (1996) que nĂŁo se caracteriza pela “palavração”, onde um fala e muitos acatam. A prática destacada Ă© voltada ao diálogo, onde há oportunidade de troca de ideias e tomada de decisões, abrindo espaço para a esperança. Para o autor, a esperança nĂŁo Ă© inerte e nĂŁo produz encontros estĂ©reis, mas Ă© a prĂłpria produção da emancipação humana. A desesperança, ao contrário, Ă© a esperança que perdeu a razĂŁo de ser. O que Freire (1996) propõe Ă© que o educador cuide da esperança para que nĂŁo vire desesperança, já que ela Ă© geradora de uma realidade distinta. A esperança precisa estar vinculada Ă criticidade, pois Ă© a crĂtica que desmitificará uma esperança ingĂŞnua. AlĂ©m do amor e da humildade, Freire cita que para que haja diálogo Ă© preciso ter fĂ© nos homens, pois se nĂŁo se vĂŞ possibilidade de mudança nos homens e no mundo nĂŁo há diálogo. Essa fĂ© nos homens pode ser descrita aqui tambĂ©m como fĂ© nas crianças e sobre o que elas tĂŞm para dizer
Management of Metastatic Endometrial Cancer: Physicians' Choices Beyond the First Line. A MITO Survey
BACKGROUND: Endometrial cancer (EC) therapeutic and diagnostic approaches have been changed by the development of a new prognostic molecular classification, the introduction of dostarlimab in microsatellite instability (MSI) high pre-treated advanced EC patients with further expected innovation deriving from lenvatinib plus pembrolizumab regardless MSI status. How this is and will be translated and embedded in the clinical setting in Italy is not known; this is why we developed Multicentre Italian Trials in Ovarian cancer and gynaecologic malignancies (MITO) survey on the current practice and expected future changes in EC. METHODS: We designed a self-administered, multiple-choice online questionnaire available only for MITO members for one month, starting in April 2021. RESULTS: 75.6% of the respondents were oncologists with a specific focus on gynaecologic malignancies and 73.3% of the respondents declared the availability of clinical trials in second line treatment for advanced EC. The therapeutic algorithm in second line was heterogeneous, being the most frequent choice administering anthracyclines followed by endocrine therapy or enrolling in clinical trials. While more than half of the clinicians declared that they performed the molecular classification, only six/45 respondents (13.3%) ran all the tests needed for it. On the other hand, 80% of them declared regular assessment of MSI status with IHC as recommended. The therapeutic approach in MSI high advanced EC patients has changed since dostarlimab approval. Indeed the most frequent choice in second line has been chemotherapy (53.3%) before its availability, while dostarlimab has been preferred in more than three-fourths of the cases (75.6%) after its approval. As for MSS patients, 77.8% of clinicians would choose lenvatinib plus pembrolizumab for them in second line once approved. CONCLUSIONS: Despite the selected sample of respondents from Italian MITO centres showing good knowledge of diagnostic and therapeutic innovations in EC, these are not fully implemented in everyday clinics, except for MSI status assessment
Management of metastatic endometrial cancer: physicians’ choices beyond the first line after approval of checkpoint inhibitors
IntroductionEndometrial cancer (EC) represents 3.4% of all newly diagnosed cancer cases and is responsible for 2.1% of all cancer-related deaths. Approximately 10%–15% of women with EC are diagnosed with advanced-stage disease, resulting in a reported 5-year survival rate of only 17% for those with distant metastases. A better understanding of its molecular features has ushered in a new era of immunotherapy for the treatment of EC, allowing for alternative therapeutic approaches, even in cases of advanced disease.MethodsWe administered a multi-choice online survey for Multicenter Italian Trials in Ovarian cancer and gynecologic malignancies (MITO) members. The questionnaire was available for 2 months, starting in October 2022. Our objective was to evaluate the current attitude of incorporating molecular characterization of EC into routine clinical practice, appraise the implementation of newly available therapies, and compare the outcomes with the previous survey conducted in April–May 2021 to ascertain the actual changes that have transpired during this recent time period.ResultsThe availability of molecular classification in Italian centers has changed in 1 year. Seventy-five percent of centers performed the molecular classification compared with 55.6% of the previous survey. Although this percentage has increased, only 18% performed all the tests. Significant changes have occurred in the administration of new treatments in EC patients in MITO centers. In 2022, 82.1% of the centers administrated dostarlimab in recurrent or advanced MMR-deficient (dMMR) EC experiencing disease progression after platinum-based chemotherapy regimens, compared to only 24.4% in 2021. In 2022, 85.7% of the centers already administrated the pembrolizumab plus lenvatinib combination as a second-line therapy for MMR-proficient (pMMR) patients with advanced or recurrent EC who had progressed from first-line platinum-based therapy.ConclusionBoth the therapeutic and diagnostic scenarios have changed over the last couple of years in MITO centers, with an increased prescription of immune checkpoint inhibitors and use of the molecular classification