Permanent Objects, Disposable Systems

4th International Conference on Open RepositoriesThis presentation was part of the session : Conference PresentationsDate: 2009-05-19 01:00 PM – 02:30 PMThe California Digital Library (CDL) preservation program is re-envisioning its curation infrastructure as a set of loosely-coupled, distributed micro-services. There are many monolithic systems that support a range of preservation activities but also require the user and the hosting institution to buy-in to a particular system culture. The result is an institution that becomes, say, a DSpace, Fedora, or LOCKSS "shop", with a specific worldview and set of object flows and structures that will eventually need to be abandoned when it comes time to transition to the next system. Experience shows that these transitions are unavoidable, despite claims that once an object is in the system, it will be safe forever. In view of this it is safer and more cost-effective to acknowledge from the outset the inevitable transient nature of systems and to plan on managing, rather than resisting change. The disruption caused by change can be mitigated by basing curation services on simple universal structures and protocols (e.g., filesystems, HTTP) and micro-services that operate on them. We promote a "mix and match" approach in which appropriate content- and context-specific curation workflows can be nimbly constructed by combining necessary functions drawn from a granular set of independent micro-services. Micro-services, whether deployed in isolation or in combination, are especially suited to exploitation upstream towards content creators who normally don't want to think about preservation, especially if it's costly; compared to buying into an entire curation culture, it is easy to adopt a small, inexpensive tool that requires very little commitment. We see digital curation as an ongoing process of enrichment at all stages in the lifecycle of a digital object. Because the early developmental stages are so critical to an object's health and longevity, it is desirable to push curation "best practices" as far upstream towards the object creators as possible. If preservation is considered only when objects are close to retirement, it is often too late to correct the structural and semantic deficiencies that can impair object usability. The later the intervention, the more expensive the correction process, and it is always difficult to fund interventions for "has been" objects. In contrast, early stage curation challenges traditional practices. Traditionally, preservation actions are often based on end-stage processing, where objects are deposited "as is" and kept out of harm's way by limiting access (i.e., dark archives). While some systems are designed to be dark or "dim", with limited access and little regard for versioning or object enrichment, enrichment and access are now seen as necessary curation actions, that is, interventions for the sake of preservation. In particular, the darkness of an entire collection can change in the blink of an eye, for example, as the result of a court ruling or access rights purchase; turning the lights on for a collection should be as simple as throwing a switch, and not require transferring the collection from a "preservation repository" to an "access repository". Effective curation services must be flexible and easily configurable in order to respond appropriately to the wide diversity of content and content uses. To be most effective, not only should curation practices be pushed upstream but also they should be pushed out to many different contexts. The micro-services approach promotes the idea that curation is an outcome, not a place. Curation actions should be applied to content where it most usefully exists for the convenience of its creators or users. For example, high value digital assets in access repositories, or even scholars' desktops, would certainly benefit from such things as persistent identification or regular audits to discover and repair bit-level damage, functions usually available only in the context of a "preservation system" but now easily applied to content where it most usefully resides without requiring transfer to a central location

Is primary angioplasty cost effective in the UK? Results of a comprehensive decision analysis

Objective: To assess the cost effectiveness of primary angioplasty, compared with medical management with thrombolytic drugs, to achieve reperfusion after acute myocardial infarction ( AMI) from the perspective of the UK NHS. Design: Bayesian evidence synthesis and decision analytic model. Methods: A systematic review was conducted and Bayesian statistical methods used to synthesise evidence from 22 randomised control trials. Resource utilisation was based on UK registry data, published literature and national databases, with unit costs taken from routine NHS sources and published literature. Main outcome measure: Costs from a health service perspective and outcomes measured as quality-adjusted life years (QALYs). Results: For the base case, the incremental cost-effectiveness ratio of primary angioplasty was pound 9241 for each additional QALY, with a probability of being cost effective of 0.90 for a cost-effectiveness threshold of pound 20 000. Results were sensitive to variations in the additional time required to initiate treatment with primary angioplasty. Conclusions: Primary angioplasty is cost effective for the treatment of AMI on the basis of threshold cost-effectiveness values used in the NHS and subject to a delay of up to about 80 minutes. These findings are mainly explained by the superior mortality benefit and the prevention of non-fatal outcomes associated with primary angioplasty for delays of up to this length

DCC Digital Curation Manual Instalment on File Formats

The goal of digital curation is to ensure the appropriate usability of managed digital assets over time. Format is a fundamental characteristic of a digital asset that governs its ability to be used effectively. Without strong format typing a digital asset is merely an undifferentiated string of bits. The information content encoded into an asset’s bits can only be interpreted properly and rendered in human-sensible form if that asset’s format is known. While it is possible for bits to be preserved indefinitely without consideration of format, it is only through the careful management of format that the meaning of those bits remains accessible over time. This instalment investigates aspects of format description, validation, and characterisation that may assist with long-term curation and usability of data

Assessing the effectiveness of primary angioplasty compared with thrombolysis and its relationship to time delay: a Bayesian evidence synthesis

Background: Meta-analyses of trials have shown greater benefits from angioplasty than thrombolysis after an acute myocardial infarction, but the time delay in initiating angioplasty needs to be considered. Objective: To extend earlier meta-analyses by considering 1- and 6-month outcome data for both forms of reperfusion. To use Bayesian statistical methods to quantify the uncertainty associated with the estimated relationships. Methods: A systematic review and meta-analysis published in 2003 was updated. Data on key clinical outcomes and the difference between time-to-balloon and time-to-needle were independently extracted by two researchers. Bayesian statistical methods were used to synthesise evidence despite differences between reported follow-up times and outcomes. Outcomes are presented as absolute probabilities of specific events and odds ratios (ORs; with 95% credible intervals (Crl)) as a function of the additional time delay associated with angioplasty. \ Results: 22 studies were included in the meta-analysis, with 3760 and 3758 patients randomised to primary angioplasty and thrombolysis, respectively. The mean ( SE) angioplasty-related time delay ( over and above time to thrombolysis) was 54.3 (2.2) minutes. For this delay, mean event probabilities were lower for primary angioplasty for all outcomes. Mortality within 1 month was 4.5% after angioplasty and 6.4% after thrombolysis ( OR = 0.68 ( 95% Crl 0.46 to 1.01)). For non-fatal reinfarction, OR = 0.32 ( 95% Crl 0.20 to 0.51); for non-fatal stroke OR = 0.24 ( 95% Crl 0.11 to 0.50). For all outcomes, the benefit of angioplasty decreased with longer delay from initiation. Conclusions: The benefit of primary angioplasty, over thrombolysis, depends on the former's additional time delay. For delays of 30-90 minutes, angioplasty is superior for 1- month fatal and non-fatal outcomes. For delays of around 90 minutes thrombolysis may be the preferred option as assessed by 6-month mortality; there is considerable uncertainty for longer time delays

Curation Micro-Services: A Pipeline Metaphor for Repositories

The effective long-term curation of digital content requires expert analysis, policy setting, and decision making, and a robust technical infrastructure that can effect and enforce curation policies and implement appropriate curation activities. Since the number, size, and diversity of content under curation management will undoubtedly continue to grow over time, and the state of curation understanding and best practices relative to that content will undergo a similar constant evolution, one of the overarching design goals of a sustainable curation infrastructure is flexibility. In order to provide the necessary flexibility of deployment and configuration in the face of potentially disruptive changes in technology, institutional mission, and user expectation, a useful design metaphor is provided by the Unix pipeline, in which complex behavior is an emergent property of the coordinated action of a number of simple independent components. The decomposition of repository function into a highly granular and orthogonal set of independent but interoperable micro-services is consistent with the principles of prudent engineering practice. Since each micro-service is small and self-contained, they are individually more robust and collectively easier to implement and maintain. By being freely interoperable in various strategic combinations, any number of micro-services-based repositories can be easily constructed to meet specific administrative or technical needs. Importantly, since these repositories are purposefully built from policy neutral and protocol and platform independent components to provide the function minimally necessary for a specific context, they are not constrained to conform to an infrastructural monoculture of prepackaged repository solutions. The University of California Curation Center has developed an open source micro-services infrastructure that is being used to manage the diverse digital collections of the ten campus University system and a number of non-university content partners. This paper provides a review of the conceptual design and technical implementation of this micro-services environment, a case study of initial deployment, and a look at ongoing micro-services developments

Curation Micro-Services: A Pipeline Metaphor for Repositories

The effective long-term curation of digital content requires expert analysis, policy setting, and decision making, and a robust technical infrastructure that can effect and enforce curation policies and implement appropriate curation activities. Since the number, size, and diversity of content under curation management will undoubtedly continue to grow over time, and the state of curation understanding and best practices relative to that content will undergo a similar constant evolution, one of the overarching design goals of a sustainable curation infrastructure is flexibility. In order to provide the necessary flexibility of deployment and configuration in the face of potentially disruptive changes in technology, institutional mission, and user expectation, a useful design metaphor is provided by the Unix pipeline, in which complex behavior is an emergent property of the coordinated action of a number of simple independent components. The decomposition of repository function into a highly granular and orthogonal set of independent but interoperable micro-services is consistent with the principles of prudent engineering practice. Since each micro-service is small and self-contained, they are individually more robust and collectively easier to implement and maintain. By being freely interoperable in various strategic combinations, any number of micro-services-based repositories can be easily constructed to meet specific administrative or technical needs. Importantly, since these repositories are purposefully built from policy neutral and protocol and platform independent components to provide the function minimally necessary for a specific context, they are not constrained to conform to an infrastructural monoculture of prepackaged repository solutions. The University of California Curation Center has developed an open source micro-services infrastructure that is being used to manage the diverse digital collections of the ten campus University system and a number of non-university content partners. This paper provides a review of the conceptual design and technical implementation of this micro-services environment, a case study of initial deployment, and a look at ongoing micro-services developments

in silico Surveillance: evaluating outbreak detection with simulation models

Background Detecting outbreaks is a crucial task for public health officials, yet gaps remain in the systematic evaluation of outbreak detection protocols. The authors’ objectives were to design, implement, and test a flexible methodology for generating detailed synthetic surveillance data that provides realistic geographical and temporal clustering of cases and use to evaluate outbreak detection protocols. Methods A detailed representation of the Boston area was constructed, based on data about individuals, locations, and activity patterns. Influenza-like illness (ILI) transmission was simulated, producing 100 years ofin silico ILI data. Six different surveillance systems were designed and developed using gathered cases from the simulated disease data. Performance was measured by inserting test outbreaks into the surveillance streams and analyzing the likelihood and timeliness of detection. Results Detection of outbreaks varied from 21% to 95%. Increased coverage did not linearly improve detection probability for all surveillance systems. Relaxing the decision threshold for signaling outbreaks greatly increased false-positives, improved outbreak detection slightly, and led to earlier outbreak detection. Conclusions Geographical distribution can be more important than coverage level. Detailed simulations of infectious disease transmission can be configured to represent nearly any conceivable scenario. They are a powerful tool for evaluating the performance of surveillance systems and methods used for outbreak detection

Effects of intergroup contact and relative gratification vs. deprivation on prejudice on both sides of the U.S./Mexico status divide

A study in the U.S.–Mexican intergroup context examined how collective relative gratification (RG) versus deprivation affects the relationship between intergroup contact and interpersonal closeness and subtle prejudice towards an out‐group. Participants were Mexican university students in Mexico (N = 239) and non‐Mexican students in California (N = 90). As predicted, Mexicans experienced less gratification/higher relative deprivation (RD), and low quality intergroup contact and expressed lower interpersonal closeness and higher subtle prejudice than U.S. Americans. Differences between countries were larger amongst participants reporting higher RD. Second‐stage moderated mediation analysis showed that the mediating effects of contact between country and interpersonal closeness and subtle prejudice, respectively, were larger amongst participants who felt relatively gratified than those who felt relatively deprived. These findings underline the importance of recognizing the moderating effect of differences in the RG versus RD levels of minority and majority groups when anticipating the potential benefits of intergroup contact for prejudice reduction

Population-adjusted treatment comparisons:estimates based on MAIC (Matching-Adjusted Indirect Comparisons) and STC (Simulated Treatment Comparisons)

OBJECTIVES: To review the properties and assumptions of methods for population-adjusted treatment comparison, including Matching-Adjusted Indirect Comparison (MAIC) and Simulated Treatment Comparison (STC), and to provide guidance on their use in health technology appraisal.METHODS: Standard methods for indirect comparisons and network meta-analysis are based on aggregate data, with the key assumption that there is no difference between trials in the distribution of effect-modifying variables. Two methods which relax this assumption, MAIC and STC, are becoming increasingly common in industry-sponsored treatment comparisons, where a company has access to individual patient data (IPD) from its own trials but only aggregate information from competitor trials. Both methods use IPD to adjust for between-trial differences in covariate distributions. We review the properties of these methods in light of the wider literature on standardisation and calibration based on propensity score reweighting and covariate adjustment, which are the foundation for MAIC and STC respectively, and identify the key assumptions in the context of indirect comparisons.RESULTS: There is a lack of clarity about how and when the methods should be applied in practice, and both MAIC and STC as currently applied can only produce population-adjusted estimates that are valid for the populations in the competitor trials, rather than the target population for the decision. In addition, the fundamental distinction between “anchored” and “unanchored” forms of indirect comparison – where a common comparator arm is or is not utilised to control for between-trial differences in prognostic variables – is under-emphasised, with the unanchored comparison making assumptions that are infeasibly strong.CONCLUSIONS: We provide recommendations on how and when population adjustment methods of this type should be used in order to provide statistically valid, clinically meaningful, transparent and consistent results for any given target population, and set out the additional analyses that should be presented to support their use

Inadequacy of Self-Implemented Preventive Measures to Control Caries Increment due to Poor Dietary Habits in 6 and 12 Years Old Children in Riga, Latvia

Aim. This study investigated whether the self-implemented preventive measures practiced among the 6 and 12 years olds in Riga, Latvia can control the caries increment due to poor dietary habits among this age groups. Material and methods. Caries examination was performed on Thirty-eight 6 and thirty-nine 12 years olds by visual and bitewing radiographic examination at baseline and after 3 years. All participants and/or their parents completed dietary habits questionnaires. The data was analyzed using t-test, chi-square test, ANOVA and frequency tables, Wilcoxon and Fisher’s tests (α=0.05). Results. The mean (SD) values of caries experience at baseline/3-year period in 6- vs.12- year olds were as follows. DMFS: 0.72 (1.02)/3.13 (3.13) (p=0.0000) vs. 6.79 (5.14)/14.79 (9.86) (p=0.0000); dmfs: 11.26(8.71)/7.74 (4.86) (p=0.078) vs. 3.57 (2.03)/1.5 (0.71) (p=0.317). The statistical significance was reported only for the consumption of soft drinks (p=0.032) and sugared tea (p=0.018) for the 6 years olds, and for sugared tea (p=0.017) and number of teaspoons of sugar added to tea (p=0.0095) for the 12-years olds. There was positive caries increment in all the 6 and 12 years olds that reported significant increase in consumption of soft drinks and sugared tea, and increase daily number of teaspoons of sugar used in tea. Conclusions. The present study demonstrated high cariogenic diet among the children in Riga, which is associated with increased caries experience that the currently practiced self-implemented oral hygiene measures was not capable of controlling.publishersversionPeer reviewe