Semantics and provenance of configuration programming language μPuppet

Nowadays computing infrastructures have grown bigger in scale and more complex. Automated configuration management tools have taken the place of traditional approaches of configuration tasks, such as manual configuration and writing simple scripts, which become tedious, inefficient and error-prone to human mistakes. These tools typically contain their own specific configuration languages. In general, users write configuration specifications of the system and the tools compile them to configuration files that are deployed on each machine to change its configuration. Configuration specifications tend to be large and involve thousands of parameters and the relations between them. However automating configuration management does not prevent configuration errors that might cause system failures that are costly and time-consuming to remedy. Configuration languages normally support separation of concerns of different users, but there is limited work on access control and work flow to guarantee the correctness of the configurations when there are changes in the specifications, or the analysis tools for root causes for configuration errors. Configuration errors remains one of the dominant reasons for system failures (Oppenheimer et al., 2003). In this thesis, we argue that provenance techniques, a dynamic technique of tracking data history developed in the database field, is a natural solution to providing configuration management tools with the ability of analysing configuration errors and identifying their root causes in the configuration specifications. For this purpose, we first choose a popular configuration management tool Puppet and present μPuppet which models the operational semantics of a core subset of Puppet language. In addition, we prototype an interpreter and a parser for μPuppet and compare their validation results by using more 50 Puppet manifests against the real Puppet language. Based on the formal semantics of μPuppet, we formalise where-, expression- and dependency-provenance which track the original inputs of an output data value, the primitive operation procedure that derives an output data value and all the inputs on which a generated output depended respectively in the process of compiling the configuration specifications. Further more, we establish the static correctness properties of three forms of provenance. We prove that where- and expression-provenance satisfy these properties. We find the limitation of dependency-provenance we define that does not record the full dependency information for some unusual value-overriding semantics, which reveals the complexity of the Puppet language. We prove the partial correctness of dependency-provenance confined to a subset of μPuppet that excludes the unusual cases and propose possible solutions to deal with these unusual cases

µPuppet: A Declarative Subset of the Puppet Configuration Language

Puppet is a popular declarative framework for specifying and managing complex system configurations. The Puppet framework includes a domain-specific language with several advanced features inspired by object-oriented programming, including user-defined resource types, 'classes' with a form of inheritance, and dependency management. Like most real-world languages, the language has evolved in an ad hoc fashion, resulting in a design with numerous features, some of which are complex, hard to understand, and difficult to use correctly. We present an operational semantics for $\mu$Puppet, a representative subset of the Puppet language that covers the distinctive features of Puppet, while excluding features that are either deprecated or work-in-progress. Formalising the semantics sheds light on difficult parts of the language, identifies opportunities for future improvements, and provides a foundation for future analysis or debugging techniques, such as static typechecking or provenance tracking. Our semantics leads straightforwardly to a reference implementation in Haskell. We also discuss some of Puppet's idiosyncrasies, particularly its handling of classes and scope, and present an initial corpus of test cases supported by our formal semantics.Comment: Full version of ECOOP 2017 conference pape

Tumor cell α3β1 integrin and vascular laminin-5 mediate pulmonary arrest and metastasis

Arrest of circulating tumor cells in distant organs is required for hematogenous metastasis, but the tumor cell surface molecules responsible have not been identified. Here, we show that the tumor cell α3β1 integrin makes an important contribution to arrest in the lung and to early colony formation. These analyses indicated that pulmonary arrest does not occur merely due to size restriction, and raised the question of how the tumor cell α3β1 integrin contacts its best-defined ligand, laminin (LN)-5, a basement membrane (BM) component. Further analyses revealed that LN-5 is available to the tumor cell in preexisting patches of exposed BM in the pulmonary vasculature. The early arrest of tumor cells in the pulmonary vasculature through interaction of α3β1 integrin with LN-5 in exposed BM provides both a molecular and a structural basis for cell arrest during pulmonary metastasis

Efficacy and safety of Danlou tablets in traditional Chinese medicine for coronary heart disease: a systematic review and meta-analysis

BackgroundDanlou tablets exert auxiliary advantages in treating coronary heart disease (CHD), but a summary of evidence-based proof is lacking. This study aims to systematically evaluate Danlou tablets in treating CHD from two aspects, including efficacy and safety.MethodsBy a thorough retrieval of the four English databases, namely, PubMed, The Cochrane Library, Embase, and Web of Science, and the four Chinese databases, namely, CNKI, Wanfang, VIP database, and China Biomedical Literature Service System, we found all randomized controlled trials (RCTs) related to Danlou tablets in treating CHD. The retrieval time was from the construction of the database to April 2022. We engaged two researchers to screen the studies, extract the required data, and assess the risk of bias. We then used RevMan5.3 and STATA.14 software to conduct a meta-analysis. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was used to evaluate the quality of outcome indicators.ResultsSeventeen RCTs involving 1,588 patients were included. The meta-analysis results are displayed as follows: clinical treatment effect [risk ratio (RR) = 1.22, 95% confidence interval (CI): 1.16, 1.28, P < 0.00001], angina pectoris duration [MD = −0.2.15, 95% CI: −2.91, −1.04, P < 0.00001], angina pectoris frequency [standard mean difference (SMD) = −2.48, 95% CI: −3.42, −1.54, P < 0.00001], angina pectoris degree [SMD = −0.96, 95% CI: −1.39, −0.53, P < 0.0001], TC [MD = −0.71, 95% CI: −0.92, −0.51, P < 0.00001], TG [MD = −0.38, 95% CI: −0.53, −0.22, P < 0.00001], low-density lipoprotein cholesterol [MD = −0.64, 95% CI: −0.76, −0.51, P < 0.00001], high-density lipoprotein cholesterol [MD = 0.16, 95% CI: 0.11, 0.21, P < 0.00001], and adverse events [RR = 0.46, 95% CI: 0.24, 0.88, P = 0.02].ConclusionThe current evidence suggests that the combination of Danlou tablets and Western medicine can enhance the efficacy of CHD and does not increase adverse events. However, because of the limited number and quality of the included studies, the results of our study should be treated with caution. Further large-scale RCTs are necessary to verify the benefits of this approach

Defect and strain in hydrogen and helium coimplanted single-crystal silicon

In this paper we studied the processes of blistering and exfoliation on the surface of crystal silicon, the evolution of defects/strains in the crystal silicon caused by hydrogen and helium coimplantation during annealing, and the formation of platelets and bubbles in the crystal. It is shown that H + and He + coimplantation produces a synergistic effect, which greatly decreases the total implantation dose, compared with either just H + or He + implantation. We also present the effect of coimplantation and analyse the different roles of H and He in the process of exfoliation during annealing. It seems that the essential role of hydrogen is to interact chemically with the defects in the silicon and create H-stabilized platelets, while the role of helium is to effuse into these platelets and exert a pressure on the inner surface of these platelets. The damage caused by coimplantation is lower than by hydrogen implantation (at the dose that exfoliation requires).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48907/2/d10102.pd

In vitro bioaccessibility and physicochemical properties of phytosterol linoleic ester synthesized from soybean sterol and linoleic acid

Phytosterols are bioactive components capable of reducing cholesterol level in serum and reducing risk of arteriosclerosis. In this study, conditions for the synthesis of maximum yield of phytosterol linoleic ester (PLE) was optimized and the physicochemical properties and in vitro bioaccessibility of the PLE were assessed. Under the optimized condition of 1:1.1 mol ratio of phytosterol and linoleoyl chloride at 80 °C for 1.5 h, the conversion rate of phytosterol reached 96.1%. Its solubility in oil increased 20 times, up to 33.8%. Also, peroxide value of PLE was much lower than linoleic acid (32.9 and 47.0 mmol/kg), which means better oxidative stability. Bioaccessibility of PLE was affected by time, concentration of bile extract, and dissolved medium. It was 4.93% alone, increased by 2.5 times compare to phytosterol; or 53.46% in oil, under the condition of 40 mg/mL bile extract for 120 min. In conclusion, under the tested condition, phytosterol conversion rate, its solubility in oil and bioaccessibility were improved significantly. The method showed great potential in manufacture high quality and quantity of PLE

Exogenous spermidine improved drought tolerance in Ilex verticillata seedlings

Winterberry (Ilex verticillata (L.) A. Gray) is a recently introduced ornamental tree species in China that has not been closely investigated for its drought resistance. In this study, we used two-year-old cuttings from I. verticillata (L.) A. Gray and two representative varieties derived from it, I. verticillata ‘Oosterwijk’ and I. verticillata ‘Jim Dandy’, as materials to investigate how this plant responds to drought stress and whether exogenous spermidine (SPD) can alleviate the negative effects caused by drought stress. The results showed that as the degree of drought stress increased, the leaves of winterberry seedlings became chlorotic, and their edges became dry. Similarly, the relative water content, specific leaf weight, chlorophyll content, leaf nitrogen content, net photosynthetic rate, stomatal conductance and transpiration rate were significantly reduced, whereas the content of malondialdehyde continuously increased with the degree of drought stress. The activities of superoxide dismutase, peroxidase, and catalase increased under moderate drought stress and then decreased under severe drought stress. The levels of soluble sugar and abscisic acid continued to increase, while those of auxin and gibberellic acid decreased. When compared with individual drought stress, an increase in the amount of external SPD clearly alleviated the effect of drought stress on winterberry seedlings. The combined phenotypes and physiological indices of the winterberry leaves under drought stress conditions revealed that the drought resistance of the native species was significantly higher than its two varieties. This finding serves as an important theoretical foundation for the popularization and application of I. verticillata (L.) A. Gray and the two varieties