Development and evaluation of the impulse transfer function technique

The development of the test/analysis technique known as the impulse transfer function (ITF) method is discussed. This technique, when implemented with proper data processing systems, should become a valuable supplement to conventional dynamic testing and analysis procedures that will be used in the space shuttle development program. The method can relieve many of the problems associated with extensive and costly testing of the shuttle for transient loading conditions. In addition, the time history information derived from impulse testing has the potential for being used to determine modal data for the structure under investigation. The technique could be very useful in determining the time-varying modal characteristics of structures subjected to thermal transients, where conventional mode surveys are difficult to perform

Implementation and extension of the impulse transfer function method for future application to the space shuttle project. Volume 1: Analysis and correlation studies

Computer programming, data processing, and a correlation study that employed data collected in the first phase test were used to demonstrate that standard test procedures and equipment could be used to collect a significant number of transfer functions from tests of the Lunar Module test article LTA-11. The testing consisted of suspending the vehicle from the apex fittings of the outrigger trusses through a set of air springs to simulate the free-free state. Impulsive loadings were delivered, one at a time, at each of the landing gear's attachment points, in three mutually perpendicular directions; thus a total of 36 impulses were applied to the vehicle. Time histories of each pulse were recorded on magnetic tape along with 40 channels of strain gage response and 28 channels of accelerometer response. Since an automated data processing system was not available, oscillograph playbacks were made of all 2400 time histories as a check on the validity of the data taken. In addition, one channel of instrumentation was processed to determine its response to a set of forcing functions from a prior LTA-11 drop test. This prediction was compared with drop test results as a first measure of accuracy

Do Interactions Between Environmental Chemicals and the Human Microbiome Need to Be Considered in Risk Assessments?

One of the most dynamic and fruitful areas of current health‐related research concerns the various roles of the human microbiome in disease. Evidence is accumulating that interactions between substances in the environment and the microbiome can affect risks of disease, in both beneficial and adverse ways. Although most of the research has concerned the roles of diet and certain pharmaceutical agents, there is increasing interest in the possible roles of environmental chemicals. Chemical risk assessment has, to date, not included consideration of the influence of the microbiome. We suggest that failure to consider the possible roles of the microbiome could lead to significant error in risk assessment results. Our purpose in this commentary is to summarize some of the evidence supporting our hypothesis and to urge the risk assessment community to begin considering and influencing how results from microbiome‐related research could be incorporated into chemical risk assessments. An additional emphasis in our commentary concerns the distinct possibility that research on chemical–microbiome interactions will also reduce some of the significant uncertainties that accompany current risk assessments. Of particular interest is evidence suggesting that the microbiome has an influence on variability in disease risk across populations and (of particular interest to chemical risk) in animal and human responses to chemical exposure. The possible explanatory power of the microbiome regarding sources of variability could reduce what might be the most significant source of uncertainty in chemical risk assessment.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151980/1/risa13316_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151980/2/risa13316.pd

Advancing human health risk assessment

Acknowledgements: The European Food Safety Authority (EFSA) and authors wish to thank the participants of the break‐out session ‘Advancing risk assessment science – Human health’ at EFSA's third Scientific Conference ‘Science, Food and Society’ (Parma, Italy, 18–21 September 2018) for their active and valuable contributions to the discussion. We also thank Hans Verhagen for carefully proofreading it.Peer reviewedPublisher PD

Comparison of serological and symptomatic diagnosis of Zika virus infection using the reporter virus particle (RVP) neutralization assay on samples from Atlántico, Colombia

Background: Zika virus associated morbidities have prompted a global response to Zika infection detection. Recommended serological tests make diagnostics difficult because of cross-reactivity to other flaviviruses and restriction to laboratory availability. In resource-limited settings where Zika is endemic, it is necessary to assess the utility of clinical symptoms as a standard diagnostic strategy for Zika. This study uses a reporter virus particle (RVP) neutralizing antibody assay to evaluate symptomatic clinical diagnosis of Zika virus. Methods: Serum and plasma samples collected from patients from Atlántico, Colombia who reported clinically defined symptoms of Zika between October 2015 and June 2016 were tested for neutralizing antibodies to Zika virus H/PF/2013 and dengue-II using RVPs. Standard curves against known antibody concentrations were generated to determine specificity of RVPs for analysis. A result was positive if the Zika antibody inhibitory concentration (IC) to 50% of the RVPs was two-fold greater than corresponding dengue IC 50%. Positive predictive value of symptomatic diagnosis was determined. Prevalence odds ratio was used to compare RVP assay determined Zika infection status to patient symptoms, number of symptoms, and time since infection. Regression analysis was used to assess changes in IC titers due to symptoms. Statistical analysis was conducted using SAS (9.4). Results: The RVP analysis was specific for Zika H/PF/2013 and dengue-II virus antibodies. Among the 77 patient specimens analyzed, 53 were Zika positive through RVP analysis, 19 negative, and 4 demonstrated an indeterminate result. The average number of days between symptoms and collection date was 37 days. Patients were on average 44 years old, and more than half were female (69.14%). Half of all patients had 6-8 symptoms. The positive predictive value of symptomatic diagnosis was 69%. Of the eight symptoms assessed symptom type, number of symptoms, collection time, and age had no significant correlation with a positive result compared to negative cases. Neither collection time since symptoms nor age had a significant impact on Zika infection status. Increases in IC 50% for Zika or for dengue-II did not relate to number or type of symptoms. Presence of skin rash was positively associated with a 90% IC antibody titer to dengue-II (p\u3c0.05). Discussion: Symptomatic diagnosis of Zika virus in Colombia may be not useful in the absence of laboratory capacity, and may not be enough to rule out other arboviral diseases. Further study is needed to assess the impact of previous flavivirus history on RVP positivity results