Integrating Scale Out and Fault Tolerance in Stream Processing using Operator State Management

As users of big data applications expect fresh results, we witness a new breed of stream processing systems (SPS) that are designed to scale to large numbers of cloud-hosted machines. Such systems face new challenges: (i) to benefit from the pay-as-you-go model of cloud computing, they must scale out on demand, acquiring additional virtual machines (VMs) and parallelising operators when the workload increases; (ii) failures are common with deployments on hundreds of VMs - systems must be fault-tolerant with fast recovery times, yet low per-machine overheads. An open question is how to achieve these two goals when stream queries include stateful operators, which must be scaled out and recovered without affecting query results. Our key idea is to expose internal operator state explicitly to the SPS through a set of state management primitives. Based on them, we describe an integrated approach for dynamic scale out and recovery of stateful operators. Externalised operator state is checkpointed periodically by the SPS and backed up to upstream VMs. The SPS identifies individual operator bottlenecks and automatically scales them out by allocating new VMs and partitioning the check-pointed state. At any point, failed operators are recovered by restoring checkpointed state on a new VM and replaying unprocessed tuples. We evaluate this approach with the Linear Road Benchmark on the Amazon EC2 cloud platform and show that it can scale automatically to a load factor of L=350 with 50 VMs, while recovering quickly from failures. Copyright © 2013 ACM

Making State Explicit for Imperative Big Data Processing

Data scientists often implement machine learning algorithms in imperative languages such as Java, Matlab and R. Yet such implementations fail to achieve the performance and scalability of specialised data-parallel processing frameworks. Our goal is to execute imperative Java programs in a data-parallel fashion with high throughput and low latency. This raises two challenges: how to support the arbitrary mutable state of Java programs without compromising scalability, and how to re cover that state after failure with low overhead. Our idea is to infer the dataflow and the types of state accesses from a Java program and use this information to generate a stateful dataflow graph (SDG) . By explicitly separating data from mutablestate, SDGs have specific features to enable this translation: to ensure scalability, distributed state can be partitioned across nodes if computation can occur entirely in parallel; if this is not possible, partial state gives nodes local instances for independent computation, which are reconciled according to application semantics. For fault tolerance, large inmemory state is checkpointed asynchronously without global coordination. We show that the performance of SDGs for several imperative online applications matches that of existing data-parallel processing frameworks

Reliability in long-term clinical studies of disease-modifying therapies for relapsing-remitting multiple sclerosis: A systematic review

Background Although relapsing-remitting multiple sclerosis (RRMS) has a chronic course, little information is known about the comparison between the disease-modifying therapies (DMT) for long-term outcomes. We aimed to conduct a systematic review of randomized clinical trial (RCT) extension and observational studies to examine the efficacy and safety of all available DMT for RRMS, compare the evidence with that derived from mid-term studies, and investigate whether the published long-term data are robust and reliable enough to inform clinical decision-making concerning RRMS treatment. Method PubMed, Scopus, and manual searches were performed until October 2019. The clinical outcomes of long- and mid-term studies were compared. ROBINS-I was used to assess the methodological qualities of the long-term studies. PROSPERO number CRD42019123361. Results Nineteen long-term studies (9,018 participants) were included in the systematic review. All studies presented serious or critical risks of bias that were mainly due to confounding, selection, and missing data biases. The annualised relapse rates (ARR) observed in the long-term studies are lower (better) than those from the mid-term studies for most treatments. The main reason for this ARR decrease could be a selection bias for good responders in the long-term studies, since many studies show a loss of patients between the mid- and long-term phases. The safety profiles depend on the study, follow-up, report, and outcome (i.e., discontinuation or number of patients with at least one serious adverse event). Conclusion The currently available long-term data for patients with RRMS exhibit serious or critical risks of bias that preclude robust comparisons between long-term studies. High quality comparative observational studies with long-term follow-ups or RCT extensions with intention-to-treat analyses are needed to support clinical and regulatory practice. Until reliable long-term evidence is available, neurologists should continue to base their conduct on mid-term studies, patients experience and, most importantly, patients needs and predictor factors, according to personalized medicine

VVV-WIT-04: An extragalactic variable source caught by the VVV Survey

We report the discovery of VVV-WIT-04, a near-infrared variable source towards the Galactic disk located ~0.2 arcsec apart from the position of the radio source PMN J1515-5559. The object was found serendipitously in the near-IR data of the ESO public survey VISTA Variables in the V\'ia L\'actea (VVV). Our analysis is based on variability, multicolor, and proper motion data from VVV and VVV eXtended surveys, complemented with archive data at longer wavelengths. We suggest that VVV-WIT-04 has an extragalactic origin as the near-IR counterpart of PMN J1515-5559. The Ks-band light-curve of VVV-WIT-04 is highly variable and consistent with that of an Optically Violent Variable (OVV) quasar. The variability in the near-IR can be interpreted as the redshifted optical variability. Residuals to the proper motion varies with the magnitude suggesting contamination by a blended source. Alternative scenarios, including a transient event such as a nova or supernova, or even a binary microlensing event are not in agreement with the available data.R.K.S. acknowledges support from CNPq/Brazil through projects 308968/2016-6 and 421687/2016-9. P.W.L. is supported by STFC Consolidated Grant ST/R000905/1. Support for the authors is provided by the BASAL CONICYT Center for Astrophysics and Associated Technologies (CATA) through grant AFB-170002, and the Ministry for the Economy, Development, and Tourism, Programa Iniciativa Cient´ıfica Milenio through grant IC120009, awarded to the Millennium Institute of Astrophysics (MAS). D.M. acknowledges support from FONDECYT through project Regular #1170121

Deficiency of vitamins C and E in women of childbearing age in Brazil: a systematic review and meta-analysis

Background: Despite current policies of salt iodination, iodine deficiency is still a global public health problem, especially in women. So far, conflicting evidence has been suggested for the prevalence of iodine deficiency in Brazil. Objective: To estimate the prevalence of iodine deficiency and associated factors in women of childbearing age in Brazil. Methods: A systematic review was conducted using databases (PubMed, LILACS, WHO, Scopus, and Capes dissertation and thesis), from inception to May 2020. Meta-analyses of proportions were performed using the variance inverse for the fixed model. Reporting and methodological quality were assessed using the Joanna Briggs Institute tool to prevalence studies. Results: Our review identified seven studies published between 2002 e 2017, including 1354 participants, especially pregnant women. All studies presented at least one quality limitation, mainly regarding the sampling method (i.e., convenience) and small sample size. The prevalence of iodine deficiency ranged among studies from 16% to 62%. In contrast, the meta-analysis identified a mean prevalence of 40% (95% confidence interval, CI 37%-43%) for pregnant women and 13% (95% CI 4%-24%) for non-pregnant women. Cumulative meta-analysis suggests a tendency of higher iodine deficiency prevalence from 2018 in pregnant women. Conclusions: Although this systematic review identified studies with poor methodological and reporting quality, a high prevalence of iodine deficiency was identified in pregnant women, reinforcing the importance of national nutritional policies for monitoring iodine status in this population. Future studies should consider random probabilistic sampling, appropriate sample size, and pre-defined subgroup analysis to adequately inform the prevalence of iodine deficiency and associated factors in women of childbearing age and support health policies

Effects of trade barriers on development and growth

A basic definition of trade barriers could be ‘all factors that influence the amount of goods and services shipped across international borders’ (Feenstra and Taylor, 2017a). This definition is quite neutral, and it needs to be understood that the word ‘barrier’ has a negative connotation, which means that a trade barrier would be any instrument that limits or restrict trade between countries, as opposed to free trade. It is generally accepted that free trade is good for productivity and economic growth, but it is also true that most countries apply some sort of trade restriction, for different reasons

Removing exogenous information using pedigree data

Management of certain populations requires the preservation of its pure genetic background. When, for different reasons, undesired alleles are introduced, the original genetic conformation must be recovered. The present study tested, through computer simulations, the power of recovery (the ability for removing the foreign information) from genealogical data. Simulated scenarios comprised different numbers of exogenous individuals taking partofthe founder population anddifferent numbers of unmanaged generations before the removal program started. Strategies were based on variables arising from classical pedigree analyses such as founders? contribution and partial coancestry. The ef?ciency of the different strategies was measured as the proportion of native genetic information remaining in the population. Consequences on the inbreeding and coancestry levels of the population were also evaluated. Minimisation of the exogenous founders? contributions was the most powerful method, removing the largest amount of genetic information in just one generation.However, as a side effect, it led to the highest values of inbreeding. Scenarios with a large amount of initial exogenous alleles (i.e. high percentage of non native founders), or many generations of mixing became very dif?cult to recover, pointing out the importance of being careful about introgression events in populatio

Iodine deficiency in women of childbearing age in Brazil: systematic review and meta-analysis

Background: Despite current policies of salt iodination, iodine deficiency is still a global public health problem, especially in women. So far, conflicting evidence has been suggested for the prevalence of iodine deficiency in Brazil. Objective: To estimate the prevalence of iodine deficiency and associated factors in women of childbearing age in Brazil. Methods: A systematic review was conducted using databases (PubMed, LILACS, WHO, Scopus, and Capes dissertation and thesis), from inception to May 2020. Meta-analyses of proportions were performed using the variance inverse for the fixed model. Reporting and methodological quality were assessed using the Joanna Briggs Institute tool to prevalence studies. Results: Our review identified seven studies published between 2002 e 2017, including 1354 participants, especially pregnant women. All studies presented at least one quality limitation, mainly regarding the sampling method (i.e., convenience) and small sample size. The prevalence of iodine deficiency ranged among studies from 16% to 62%. In contrast, the meta-analysis identified a mean prevalence of 40% (95% confidence interval, CI 37%-43%) for pregnant women and 13% (95% CI 4%-24%) for non-pregnant women. Cumulative meta-analysis suggests a tendency of higher iodine deficiency prevalence from 2018 in pregnant women. Conclusions: Although this systematic review identified studies with poor methodological and reporting quality, a high prevalence of iodine deficiency was identified in pregnant women, reinforcing the importance of national nutritional policies for monitoring iodine status in this population. Future studies should consider random probabilistic sampling, appropriate sample size, and pre-defined subgroup analysis to adequately inform the prevalence of iodine deficiency and associated factors in women of childbearing age and support health policies.</jats:p

No link between handedness and spatial navigation: evidence from over 400 000 participants in 41 countries

There is an active debate concerning the association of handedness and spatial ability. Past studies used small sample sizes. Determining the effect of handedness on spatial ability requires a large, cross-cultural sample of participants and a navigation task with real-world validity. Here, we overcome these challenges via the mobile app Sea Hero Quest. We analysed the navigation performance from 422 772 participants from 41 countries and found no reliable evidence for any difference in spatial ability between leftand right-handers across all countries. A small but growing gap in performance appears for participants over 64 years old, with left-handers outperforming right-handers. Further analysis, however, suggests that this gap is most likely due to selection bias. Overall, our study clarifies the factors associated with spatial ability and shows that left-handedness is not associated with either a benefit or a deficit in spatial ability