Cloud-edge hybrid applications

Many modern applications are designed to provide interactions among users, including multi- user games, social networks and collaborative tools. Users expect application response time to be in the order of milliseconds, to foster interaction and interactivity. The design of these applications typically adopts a client-server model, where all interac- tions are mediated by a centralized component. This approach introduces availability and fault- tolerance issues, which can be mitigated by replicating the server component, and even relying on geo-replicated solutions in cloud computing infrastructures. Even in this case, the client-server communication model leads to unnecessary latency penalties for geographically close clients and high operational costs for the application provider. This dissertation proposes a cloud-edge hybrid model with secure and ecient propagation and consistency mechanisms. This model combines client-side replication and client-to-client propagation for providing low latency and minimizing the dependency on the server infras- tructure, fostering availability and fault tolerance. To realize this model, this works makes the following key contributions. First, the cloud-edge hybrid model is materialized by a system design where clients maintain replicas of the data and synchronize in a peer-to-peer fashion, and servers are used to assist clients’ operation. We study how to bring most of the application logic to the client-side, us- ing the centralized service primarily for durability, access control, discovery, and overcoming internetwork limitations. Second, we dene protocols for weakly consistent data replication, including a novel CRDT model (∆-CRDTs). We provide a study on partial replication, exploring the challenges and fundamental limitations in providing causal consistency, and the diculty in supporting client- side replicas due to their ephemeral nature. Third, we study how client misbehaviour can impact the guarantees of causal consistency. We propose new secure weak consistency models for insecure settings, and algorithms to enforce such consistency models. The experimental evaluation of our contributions have shown their specic benets and limitations compared with the state-of-the-art. In general, the cloud-edge hybrid model leads to faster application response times, lower client-to-client latency, higher system scalability as fewer clients need to connect to servers at the same time, the possibility to work oine or disconnected from the server, and reduced server bandwidth usage. In summary, we propose a hybrid of cloud-and-edge which provides lower user-to-user la- tency, availability under server disconnections, and improved server scalability – while being ecient, reliable, and secure.Muitas aplicações modernas são criadas para fornecer interações entre utilizadores, incluindo jogos multiutilizador, redes sociais e ferramentas colaborativas. Os utilizadores esperam que o tempo de resposta nas aplicações seja da ordem de milissegundos, promovendo a interação e interatividade. A arquitetura dessas aplicações normalmente adota um modelo cliente-servidor, onde todas as interações são mediadas por um componente centralizado. Essa abordagem apresenta problemas de disponibilidade e tolerância a falhas, que podem ser mitigadas com replicação no componente do servidor, até com a utilização de soluções replicadas geogracamente em infraestruturas de computação na nuvem. Mesmo neste caso, o modelo de comunicação cliente-servidor leva a penalidades de latência desnecessárias para clientes geogracamente próximos e altos custos operacionais para o provedor das aplicações. Esta dissertação propõe um modelo híbrido cloud-edge com mecanismos seguros e ecientes de propagação e consistência. Esse modelo combina replicação do lado do cliente e propagação de cliente para cliente para fornecer baixa latência e minimizar a dependência na infraestrutura do servidor, promovendo a disponibilidade e tolerância a falhas. Para realizar este modelo, este trabalho faz as seguintes contribuições principais. Primeiro, o modelo híbrido cloud-edge é materializado por uma arquitetura do sistema em que os clientes mantêm réplicas dos dados e sincronizam de maneira ponto a ponto e onde os servidores são usados para auxiliar na operação dos clientes. Estudamos como trazer a maior parte da lógica das aplicações para o lado do cliente, usando o serviço centralizado principalmente para durabilidade, controlo de acesso, descoberta e superação das limitações inter-rede. Em segundo lugar, denimos protocolos para replicação de dados fracamente consistentes, incluindo um novo modelo de CRDTs (∆-CRDTs). Fornecemos um estudo sobre replicação parcial, explorando os desaos e limitações fundamentais em fornecer consistência causal e a diculdade em suportar réplicas do lado do cliente devido à sua natureza efémera. Terceiro, estudamos como o mau comportamento da parte do cliente pode afetar as garantias da consistência causal. Propomos novos modelos seguros de consistência fraca para congurações inseguras e algoritmos para impor tais modelos de consistência. A avaliação experimental das nossas contribuições mostrou os benefícios e limitações em comparação com o estado da arte. Em geral, o modelo híbrido cloud-edge leva a tempos de resposta nas aplicações mais rápidos, a uma menor latência de cliente para cliente e à possibilidade de trabalhar oine ou desconectado do servidor. Adicionalmente, obtemos uma maior escalabilidade do sistema, visto que menos clientes precisam de estar conectados aos servidores ao mesmo tempo e devido à redução na utilização da largura de banda no servidor. Em resumo, propomos um modelo híbrido entre a orla (edge) e a nuvem (cloud) que fornece menor latência entre utilizadores, disponibilidade durante desconexões do servidor e uma melhor escalabilidade do servidor – ao mesmo tempo que é eciente, conável e seguro

Exome sequencing and functional analyses suggest that SIX6 is a gene involved in an altered proliferation-differentiation balance early in life and optic nerve degeneration at old age

Primary open-angle glaucoma (POAG) is a hereditary neurodegenerative disease, characterized by optic nerve changes including increased excavation, notching and optic disc hemorrhages. The excavation can be described by the vertical cup-disc ratio (VCDR). Previously, genome-wide significant evidence for the association of rs10483727 in SIX1-SIX6 locus with VCDR and subsequent POAG was found. Using 1000 genomes-based imputation of four independent population-based cohorts in the Netherlands, we identified a missense variant rs33912345 (His141Asn) in SIX6 associated with VCDR (Pmeta = 7.74 × 10-7, n = 11 473) and POAG (Pmeta = 6.09 × 10-3, n = 292). Exome sequencing analysis revealed another missense variant rs146737847 (Glu129Lys) also in SIX6 associated with VCDR (P = 5.09 × 10-3, n = 1208). These two findings point to SIX6 as the responsible gene for the previously reported association signal. Functional characterization of SIX6 in zebrafish revealed that knockdown of six6b led to a small eye phenotype. Histological analysis showed retinal lamination, implying an apparent normal development of the eye, but an underdeveloped lens, and reduced optic nerve diameter. Expression analysis of morphants at 3 dpf showed a 5.5-fold up-regulation of cdkn2b, a cyclin-dependent kinase inhibitor, involved in cell cycle regulation and previously associated with VCDR and POAG in genome-wide association studies (GWASs). Since both six6b and cdkn2b play a key role in cell proliferation, we assessed the proliferative activity in the eye of morphants and found an alteration in the proliferative pattern of retinal cells. Our findings in humans and zebrafish suggest a functional involvement of six6b in early eye development, and open new insights into the genetic architecture of POAG

Observation of associated near-side and away-side long-range correlations in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector

Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Search for the neutral Higgs bosons of the minimal supersymmetric standard model in pp collisions at root s=7 TeV with the ATLAS detector

A search for neutral Higgs bosons of the Minimal Supersymmetric Standard Model (MSSM) is reported. The analysis is based on a sample of proton-proton collisions at a centre-of-mass energy of 7TeV recorded with the ATLAS detector at the Large Hadron Collider. The data were recorded in 2011 and correspond to an integrated luminosity of 4.7 fb-1 to 4.8 fb-1. Higgs boson decays into oppositely-charged muon or τ lepton pairs are considered for final states requiring either the presence or absence of b-jets. No statistically significant excess over the expected background is observed and exclusion limits at the 95% confidence level are derived. The exclusion limits are for the production cross-section of a generic neutral Higgs boson, φ, as a function of the Higgs boson mass and for h/A/H production in the MSSM as a function of the parameters mA and tan β in the mhmax scenario for mA in the range of 90GeV to 500 GeV. Copyright CERN

Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV

The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √s = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT≥20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60≤pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2≤{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration

Search for pair-produced long-lived neutral particles decaying to jets in the ATLAS hadronic calorimeter in ppcollisions at √s=8TeV

The ATLAS detector at the Large Hadron Collider at CERN is used to search for the decay of a scalar boson to a pair of long-lived particles, neutral under the Standard Model gauge group, in 20.3fb−1of data collected in proton–proton collisions at √s=8TeV. This search is sensitive to long-lived particles that decay to Standard Model particles producing jets at the outer edge of the ATLAS electromagnetic calorimeter or inside the hadronic calorimeter. No significant excess of events is observed. Limits are reported on the product of the scalar boson production cross section times branching ratio into long-lived neutral particles as a function of the proper lifetime of the particles. Limits are reported for boson masses from 100 GeVto 900 GeV, and a long-lived neutral particle mass from 10 GeVto 150 GeV

Search for R-parity-violating supersymmetry in events with four or more leptons in sqrt(s) =7 TeV pp collisions with the ATLAS detector

A search for new phenomena in final states with four or more leptons (electrons or muons) is presented. The analysis is based on 4.7 fb−1 of $\sqrt{s}=7\;\mathrm{TeV}$ proton-proton collisions delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in two signal regions: one that requires moderate values of missing transverse momentum and another that requires large effective mass. The results are interpreted in a simplified model of R-parity-violating supersymmetry in which a 95% CL exclusion region is set for charged wino masses up to 540 GeV. In an R-parity-violating MSUGRA/CMSSM model, values of m 1/2 up to 820 GeV are excluded for 10 < tan β < 40

Search for high-mass resonances decaying to dilepton final states in pp collisions at s√=7 TeV with the ATLAS detector

The ATLAS detector at the Large Hadron Collider is used to search for high-mass resonances decaying to an electron-positron pair or a muon-antimuon pair. The search is sensitive to heavy neutral Z′ gauge bosons, Randall-Sundrum gravitons, Z * bosons, techni-mesons, Kaluza-Klein Z/γ bosons, and bosons predicted by Torsion models. Results are presented based on an analysis of pp collisions at a center-of-mass energy of 7 TeV corresponding to an integrated luminosity of 4.9 fb−1 in the e + e − channel and 5.0 fb−1 in the μ + μ −channel. A Z ′ boson with Standard Model-like couplings is excluded at 95 % confidence level for masses below 2.22 TeV. A Randall-Sundrum graviton with coupling k/MPl=0.1 is excluded at 95 % confidence level for masses below 2.16 TeV. Limits on the other models are also presented, including Technicolor and Minimal Z′ Models

Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at s√=8 TeV with the ATLAS detector

The results of a search for direct pair production of the scalar partner to the top quark using an integrated luminosity of 20.1fb−1 of proton–proton collision data at √s = 8 TeV recorded with the ATLAS detector at the LHC are reported. The top squark is assumed to decay via t˜→tχ˜01 or t˜→ bχ˜±1 →bW(∗)χ˜01 , where χ˜01 (χ˜±1 ) denotes the lightest neutralino (chargino) in supersymmetric models. The search targets a fully-hadronic final state in events with four or more jets and large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits are reported in terms of the top squark and neutralino masses and as a function of the branching fraction of t˜ → tχ˜01 . For a branching fraction of 100%, top squark masses in the range 270–645 GeV are excluded for χ˜01 masses below 30 GeV. For a branching fraction of 50% to either t˜ → tχ˜01 or t˜ → bχ˜±1 , and assuming the χ˜±1 mass to be twice the χ˜01 mass, top squark masses in the range 250–550 GeV are excluded for χ˜01 masses below 60 GeV