Investigation of characteristics of feed system instabilities

The relationship between the structural and feed system natural frequencies in structure-propulsion system coupled longitudinal oscillations (pogo) is investigated. The feed system frequencies are usually very dependent upon the compressibility (compliance) of cavitation bubbles that exist to some extent in all operating turbopumps. This document includes: a complete review of cavitation mechanisms; development of a turbopump cavitation compliance model; an accumulation and analysis of all available cavitation compliance test data; and a correlation of empirical-analytical results. The analytical model is based on the analysis of flow relative to a set of cascaded blades, having any described shape, and assumes phase changes occur under conditions of isentropic equilibrium. Analytical cavitation compliance predictions for the J-2 LOX, F-1 LOX, H-1 LOX and LR87 oxidizer turbopump inducers do not compare favorably with test data. The model predicts much less cavitation than is derived from the test data. This implies that mechanisms other than blade cavitation contribute significantly to the total amount of turbopump cavitation

Machine learning with the hierarchy‐of‐hypotheses (HoH) approach discovers novel pattern in studies on biological invasions

Research synthesis on simple yet general hypotheses and ideas is challenging in scientific disciplines studying highly context‐dependent systems such as medical, social, and biological sciences. This study shows that machine learning, equation‐free statistical modeling of artificial intelligence, is a promising synthesis tool for discovering novel patterns and the source of controversy in a general hypothesis. We apply a decision tree algorithm, assuming that evidence from various contexts can be adequately integrated in a hierarchically nested structure. As a case study, we analyzed 163 articles that studied a prominent hypothesis in invasion biology, the enemy release hypothesis. We explored if any of the nine attributes that classify each study can differentiate conclusions as classification problem. Results corroborated that machine learning can be useful for research synthesis, as the algorithm could detect patterns that had been already focused in previous narrative reviews. Compared with the previous synthesis study that assessed the same evidence collection based on experts' judgement, the algorithm has newly proposed that the studies focusing on Asian regions mostly supported the hypothesis, suggesting that more detailed investigations in these regions can enhance our understanding of the hypothesis. We suggest that machine learning algorithms can be a promising synthesis tool especially where studies (a) reformulate a general hypothesis from different perspectives, (b) use different methods or variables, or (c) report insufficient information for conducting meta‐analyses

The Impact of Political Factors on International Student Mobility

International student mobility contributes to a knowledge-based economy and forms an important component of a highly educated migration. This article aims to identify how far political factors – including political discrimination, restrictions, freedom, UK migration policies and social cultural norms and policies - enhance or inhibit individuals’ capabilities to become mobile. It offers a novel conceptualisation of mobility drawing on Structuration Theory and Capability Approach to reveal the link between structure, capability and agency in the mobility process. Semi-structured in-depth interviews were conducted with forty PhD students, two professors from Turkey in the UK and three international education experts. A capability list established shows how mobility occurs when students’ capabilities (freedoms) fail to flourish and they lose their power (capacity) to influence society due to the political environment in the home country. ‘Impo-mobility’, derived from the word ‘imposed’, is proposed to refer to highly educated people having to become mobile as a result of impositions placed upon them by home and host government political practices. An appealing political environment is necessary if Turkey is not to lose highly educated individuals and the UK is to remain a global player in international higher education

Virus Sharing, Genetic Sequencing, and Global Health Security

The WHO’s Pandemic Influenza Preparedness (PIP) Framework was a milestone global agreement designed to promote the international sharing of biological samples to develop vaccines, while that ensuring poorer countries would have access to those vaccines. Since the PIP Framework was negotiated, scientists have developed the capacity to use genetic sequencing data (GSD) to develop synthetic viruses rapidly for product development of life-saving technologies in a time-sensitive global emergency—threatening to unravel the Framework. Access to GSD may also have major implications for biosecurity, biosafety, and intellectual property (IP). By rendering the physical transfer of viruses antiquated, GSD may also undermine the effectiveness of the PIP Framework itself, with disproportionate impacts on poorer countries. We examine the changes that need to be made to the PIP Framework to address the growing likelihood that GSD might be shared instead of physical virus samples. We also propose that the international community harness this opportunity to expand the scope of the PIP Framework beyond only influenza viruses with pandemic potential. In light of non-influenza pandemic threats such as the Middle East Respiratory Syndrome (MERS) and Ebola, we call for an international agreement on the sharing of the benefits of research – such as vaccines and treatments – for other infectious diseases to ensure not only a more secure and healthy world, but also a more just world, for humanity

SIGNAL SEPARATION TO REVEAL SUBTLE FEATURES IN GRAVITY AND MAGNETIC DATA FROM THE BELLEFONTAINE OUTLIER, OHIO

Fidler, Michael L. Jr and Noltimier, Hallan C., 2006, Signal separation to review subtle features in gravity and magnetic data from the Bellefontaine outlier, Ohio [poster]: Geological Society of America North-Central Section 40th Annual Meeting, 2006, Session 38, Paper 38-2. Abstract published: Geological Society of America, Abstracts with Programs, Vol. 38, No. 4, p. 76; http://gsa.confex.com/gsa/2006NC/finalprogram/abstract_103533.htm At previous GSA meetings the general basement topography and structure of the Bellefontaine Outlier region of Ohio has been presented in poster format based upon our own detailed gravity and magnetic survey data and the COCORP Ohio #1 seismic survey which crossed the region. Recent experimentation with signal separation has brought new structural details to light. By removing the major gravity and magnetic signals from their respective data sets and re-normalizing the resulting data to isolate small scale variations, many features become visible. Correlation of these new details hidden within the gravity and magnetic survey data sets is presented as well as correlation with surface topographic features. For example: A north-east trending basement fault correlates with surface topography

Error bars in experimental biology

Error bars commonly appear in figures in publications, but experimental biologists are often unsure how they should be used and interpreted. In this article we illustrate some basic features of error bars and explain how they can help communicate data and assist correct interpretation. Error bars may show confidence intervals, standard errors, standard deviations, or other quantities. Different types of error bars give quite different information, and so figure legends must make clear what error bars represent. We suggest eight simple rules to assist with effective use and interpretation of error bars

POSTURAl CONTROL STRATEGIES IN DANCERS AND NON DANCERS

Postural stability is typically measured by assessing total excursions of either the center of pressure or whole body center of mass. One problem with measures such as these is that interpretations or postural stability are typically made without references to any stability boundaries. Further, postural control studies are typically on'y conducted on individuals with balance impairments and compared to healthy controls. Little research has been conducted on athletes with high levels of postural control. This study compares the postural dynamics of elite balancers with matched control subjects using stability measures that take into account the stability boundaries of different postures