173 research outputs found
Formal Firewall Conformance Testing: An Application of Test and Proof Techniques
Firewalls are an important means to secure critical ICT infrastructures. As configurable off-the-shelf prod\-ucts, the effectiveness of a firewall crucially depends on both the correctness of the implementation itself as well as the correct configuration. While testing the implementation can be done once by the manufacturer, the configuration needs to be tested for each application individually. This is particularly challenging as the configuration, implementing a firewall policy, is inherently complex, hard to understand, administrated by different stakeholders and thus difficult to validate. This paper presents a formal model of both stateless and stateful firewalls (packet filters), including NAT, to which a specification-based conformance test case gen\-eration approach is applied. Furthermore, a verified optimisation technique for this approach is presented: starting from a formal model for stateless firewalls, a collection of semantics-preserving policy transformation rules and an algorithm that optimizes the specification with respect of the number of test cases required for path coverage of the model are derived. We extend an existing approach that integrates verification and testing, that is, tests and proofs to support conformance testing of network policies. The presented approach is supported by a test framework that allows to test actual firewalls using the test cases generated on the basis of the formal model. Finally, a report on several larger case studies is presented
Description of the Immature Stages of Anopheles (Nyssorhynchus) rondoni (Neiva & Pinto) (Diptera: Culicidae)
Stress Distribution in Porcelain-Fused-to-Gold Crowns and Preparations Constructed with Photoelastic Plastics
Composite models representing porcelain-fused-to-gold restorations were constructed from photoelastic plastics. Better stress distributions resulted when the porcelain-gold joint was as far as feasible from the loading site, a bulk of gold was present on the lingual shoulder, and the porcelain-gold joint at the shoulder was 30° from the horizontal.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66999/2/10.1177_00220345710500053101.pd
Bio-Inspired Materials For Parsing Matrix Physicochemical Control Of Cell Migration: A Review
Cell motility is ubiquitous in both normal and pathophysiological processes. It is a complex biophysical response elicited via the integration of diverse extracellular physicochemical cues. The extracellular matrix directs cell motilityvia gradients in morphogens (a.k.a. chemotaxis), adhesive proteins (haptotaxis), and stiffness (durotaxis). Three-dimensional geometrical and proteolytic cues also constitute key regulators of motility. Therefore, cells process a variety of physicochemical signals simultaneously, while making informed decisions about migration viaintracellular processing. Over the last few decades, bioengineers have created and refined natural and synthetic in vitro platforms in an attempt to isolate these extracellular cues and tease out how cells are able to translate this complex array of dynamic biochemical and biophysical features into functional motility. Here, we review how biomaterials have played a key role in the development of these types of model systems, and how recent advances in engineered materials have significantly contributed to our current understanding of the mechanisms of cell migration
A Protocol for the Secure Linking of Registries for HPV Surveillance
In order to monitor the effectiveness of HPV vaccination in Canada the linkage of multiple data registries may be required. These registries may not always be managed by the same organization and, furthermore, privacy legislation or practices may restrict any data linkages of records that can actually be done among registries. The objective of this study was to develop a secure protocol for linking data from different registries and to allow on-going monitoring of HPV vaccine effectiveness.A secure linking protocol, using commutative hash functions and secure multi-party computation techniques was developed. This protocol allows for the exact matching of records among registries and the computation of statistics on the linked data while meeting five practical requirements to ensure patient confidentiality and privacy. The statistics considered were: odds ratio and its confidence interval, chi-square test, and relative risk and its confidence interval. Additional statistics on contingency tables, such as other measures of association, can be added using the same principles presented. The computation time performance of this protocol was evaluated.The protocol has acceptable computation time and scales linearly with the size of the data set and the size of the contingency table. The worse case computation time for up to 100,000 patients returned by each query and a 16 cell contingency table is less than 4 hours for basic statistics, and the best case is under 3 hours.A computationally practical protocol for the secure linking of data from multiple registries has been demonstrated in the context of HPV vaccine initiative impact assessment. The basic protocol can be generalized to the surveillance of other conditions, diseases, or vaccination programs
Human papillomavirus infection in honduran women with normal cytology
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80440.pdf (publisher's version ) (Closed access)OBJECTIVE: This study was aimed at estimating type-specific HPV prevalence and its cofactors among Honduran women with normal cytology in order to provide valuable information to health policymakers about the epidemiology of this important sexually transmitted infection. METHODS: A total of 591 women with normal cytology from Tegucigalpa, Honduras were interviewed and tested for HPV using the SPF10 LiPA25. A structured epidemiological questionnaire was administered to each woman. RESULTS: The overall HPV prevalence was 51%. Twenty-three types of HPV were detected; HPV 16, 51, 31, 18, and 11 were the most common. The highest prevalence of cancer associated HPV types (15.0%) was found in the women less than 35 years. Besides the association with age, the main independent predictors of HPV infection were the lifetime number of sexual partners and having a low socioeconomic status and less than 5 previous Pap smears. CONCLUSIONS: In the population studied, there was a broad diversity of HPV infections, with high-risk types being the most common types detected. The establishment of a well-characterized population with regard to the community prevalence of type-specific HPV infection will provide a valuable baseline for monitoring population effectiveness of an HPV vaccine
Resurrection of Anopheles goeldii from synonymy with Anopheles nuneztovari (Diptera, Culicidae) and a new record for Anopheles dunhami in the Brazilian Amazon
The dominant Anopheles vectors of human malaria in the Asia-Pacific region: occurrence data, distribution maps and bionomic précis
<p>Abstract</p> <p>Background</p> <p>The final article in a series of three publications examining the global distribution of 41 dominant vector species (DVS) of malaria is presented here. The first publication examined the DVS from the Americas, with the second covering those species present in Africa, Europe and the Middle East. Here we discuss the 19 DVS of the Asian-Pacific region. This region experiences a high diversity of vector species, many occurring sympatrically, which, combined with the occurrence of a high number of species complexes and suspected species complexes, and behavioural plasticity of many of these major vectors, adds a level of entomological complexity not comparable elsewhere globally. To try and untangle the intricacy of the vectors of this region and to increase the effectiveness of vector control interventions, an understanding of the contemporary distribution of each species, combined with a synthesis of the current knowledge of their behaviour and ecology is needed.</p> <p>Results</p> <p>Expert opinion (EO) range maps, created with the most up-to-date expert knowledge of each DVS distribution, were combined with a contemporary database of occurrence data and a suite of open access, environmental and climatic variables. Using the Boosted Regression Tree (BRT) modelling method, distribution maps of each DVS were produced. The occurrence data were abstracted from the formal, published literature, plus other relevant sources, resulting in the collation of DVS occurrence at 10116 locations across 31 countries, of which 8853 were successfully geo-referenced and 7430 were resolved to spatial areas that could be included in the BRT model. A detailed summary of the information on the bionomics of each species and species complex is also presented.</p> <p>Conclusions</p> <p>This article concludes a project aimed to establish the contemporary global distribution of the DVS of malaria. The three articles produced are intended as a detailed reference for scientists continuing research into the aspects of taxonomy, biology and ecology relevant to species-specific vector control. This research is particularly relevant to help unravel the complicated taxonomic status, ecology and epidemiology of the vectors of the Asia-Pacific region. All the occurrence data, predictive maps and EO-shape files generated during the production of these publications will be made available in the public domain. We hope that this will encourage data sharing to improve future iterations of the distribution maps.</p
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