Replicability of simulation studies for the investigation of statistical methods: the RepliSims project.

Results of simulation studies evaluating the performance of statistical methods can have a major impact on the way empirical research is implemented. However, so far there is limited evidence of the replicability of simulation studies. Eight highly cited statistical simulation studies were selected, and their replicability was assessed by teams of replicators with formal training in quantitative methodology. The teams used information in the original publications to write simulation code with the aim of replicating the results. The primary outcome was to determine the feasibility of replicability based on reported information in the original publications and supplementary materials. Replicasility varied greatly: some original studies provided detailed information leading to almost perfect replication of results, whereas other studies did not provide enough information to implement any of the reported simulations. Factors facilitating replication included availability of code, detailed reporting or visualization of data-generating procedures and methods, and replicator expertise. Replicability of statistical simulation studies was mainly impeded by lack of information and sustainability of information sources. We encourage researchers publishing simulation studies to transparently report all relevant implementation details either in the research paper itself or in easily accessible supplementary material and to make their simulation code publicly available using permanent links.

Protective efficacy of a Classical swine fever virus C-strain deletion mutant and ability to differentiate infected from vaccinated animals.

Classical swine fever (CSF) continues to be the most economically damaging pig disease in the world. The disease can be effectively controlled by vaccination with the live C-strain vaccine. This vaccine, however, does not enable the serological differentiation between infected and vaccinated animals (DIVA) and its use can therefore impose severe trade restrictions. CSF-specific diagnostic ELISAs detect antibodies directed against the conserved and immunodominant A domain of the E2 structural glycoprotein. We previously reported the production of a C-strain virus in which the immunodominant TAVSPTTLR epitope of the A domain is stably mutated with the aim to render the virus suitable as a DIVA vaccine. We here report that a single vaccination with this vaccine virus protected pigs from a lethal challenge dose of the highly virulent Brescia strain. Analysis of the sera, however, demonstrated that a commercially available E2 ELISA was unsuitable as an accompanying DIVA test.

Rational design of a classical swine fever C-strain vaccine virus that enables the differentiation between infected and vaccinated animals.

The C-strain of the classical swine fever virus (CSFV) is considered the gold standard vaccine for the control of CSF. This vaccine, however, does not enable the serological differentiation between infected and vaccinated animals (DIVA). Consequently, its use can impose severe trade restrictions. The immunodominant and evolutionarily conserved A-domain of the E2 structural glycoprotein is an important target in CSFV-specific ELISAs. With the ultimate aim to render the C-strain suitable as a DIVA vaccine, mutations were introduced that were expected to dampen the immunogenicity of the A-domain. In the first of two approaches, the feasibility of shielding the A-domain by N-linked glycans was evaluated, whereas in the second approach C-strain mutants were created with targeted deletions in the A-domain. Analysis of the antibody responses elicited in rabbits suggested that shielding of the A-domain by an N-linked glycan had a minor effect on the immune response against the A-domain, whereas a targeted deletion of only a single amino acid severely dampened this response. C-strain mutants with larger deletions were highly debilitated and incapable of sustained growth in vitro. By providing the viruses with the opportunity to increase their fitness by mutation, a mutant was rescued that found a way to compensate for the imposed fitness cost. Most of the identified mutations occurred in several independently evolved viruses, demonstrating parallel evolution. By virtue of this compensatory evolution, a well replicating and genetically stable C-strain mutant was produced that can be serologically differentiated from wildtype CSFV. The findings provide the molecular basis for the development of a novel, genetically stable, live attenuated CSF DIVA vaccine.

The setting process of a glass ionomer dental cement investigated by an electric conductance method.

The setting time of glass ionomer cement should be controlled accurately. If it sets too rapidly, the crystal formation is disturbed and broken up during the mixing of the cement. We studied the kinetics of the setting of a glass ionomer dental cement by an electric conductance method and found that the rate of setting is directly proportional to the increase of the power to liquid ratio (P/L).

Kinetic studies on improved phosphate dental cement: the measurement of some improved dental cements containing phosphate polymers by an electric conductance method.

The rate of the setting process of zinc phosphate dental cement with organic phosphate polymers as additives was measured by a conductance technique. There are two rate-determining parameters, namely an induction period and a first-order reaction constant. The values of the latter constant are not affected by the additives.