Multivariate Granger Causality and Generalized Variance

Granger causality analysis is a popular method for inference on directed interactions in complex systems of many variables. A shortcoming of the standard framework for Granger causality is that it only allows for examination of interactions between single (univariate) variables within a system, perhaps conditioned on other variables. However, interactions do not necessarily take place between single variables, but may occur among groups, or "ensembles", of variables. In this study we establish a principled framework for Granger causality in the context of causal interactions among two or more multivariate sets of variables. Building on Geweke's seminal 1982 work, we offer new justifications for one particular form of multivariate Granger causality based on the generalized variances of residual errors. Taken together, our results support a comprehensive and theoretically consistent extension of Granger causality to the multivariate case. Treated individually, they highlight several specific advantages of the generalized variance measure, which we illustrate using applications in neuroscience as an example. We further show how the measure can be used to define "partial" Granger causality in the multivariate context and we also motivate reformulations of "causal density" and "Granger autonomy". Our results are directly applicable to experimental data and promise to reveal new types of functional relations in complex systems, neural and otherwise.Comment: added 1 reference, minor change to discussion, typos corrected; 28 pages, 3 figures, 1 table, LaTe

Trans World Radio - Culvert Design

Trans World Radio (TWR) is a mission organization focused on broadcasting the Gospel around the world. TWR now serves 190 countries by transmitting in 275 languages, using radio to deliver the message to as many people as possible. The organization’s West Africa Transmitter Site in Benin currently has accessibility problems due to high streamflows and saturated ground conditions during the rainy season. The site also needs a secure perimeter to reduce trespassing and theft. To address these issues, our client, Garth Kennedy, Director of the West Africa Transmitter Station, has asked the team to design two culverts, one at the upstream property boundary and one at the downstream boundary. Culverts are advantageous for this scenario because they can act as a bridge, while the pipe size can be restricted to inhibit trespassing. Once the culverts are built, the fence and perimeter road can be extended over them. For both sides of the property, the team has designed a series of U-shaped, pre-cast concrete box culverts. The team calculated the design flows based on rainfall data and the topography of the site to determine the size and number of box sections. The team has also designed the culverts and the supporting concrete structures to bear the load of vehicles and the machinery on site. TWR plans to construct the pre-cast culverts on-site, and then build the supporting structures and install the culverts during their dry season.https://mosaic.messiah.edu/engr2021/1017/thumbnail.jp

Village Water Ozonation System

The Village Water Ozonation System (VWOS) team’s core mission is to provide economically sustainable and culturally sensitive drinking water solutions for communities, to empower them with the ability to properly maintain their drinking water supply, and to transform people’s lives by decreasing the occurrences of waterborne diseases. Currently, the VWOS team is partnering with Friends in Action to implement two drinking water treatment systems this summer for the community living on Rama Cay, an island in Nicaragua. The wells on the island have a high salt content and are contaminated with bacteria which makes the water unsafe to drink; therefore, these two systems consist of a Reverse Osmosis unit, a UV light and other filters to ensure clean water. VWOS is also partnering with Forward Edge International to serve Mama Beth\u27s Children\u27s Home in Kijabe, Kenya. Mama Beth\u27s serves approximately 250 children every day but their water source is heavily contaminated with bacteria. VWOS is designing a chlorination system that will provide safe water for the students with plans to implement it in the summer of 2023. Funding for this work provided by The Collaboratory for Strategic Partnerships and Applied Research.https://mosaic.messiah.edu/engr2022/1021/thumbnail.jp

Integrating neuroimaging biomarkers into the multicentre, high-dose erythropoietin for asphyxia and encephalopathy (HEAL) trial: rationale, protocol and harmonisation

Introduction: MRI and MR spectroscopy (MRS) provide early biomarkers of brain injury and treatment response in neonates with hypoxic-ischaemic encephalopathy). Still, there are challenges to incorporating neuroimaging biomarkers into multisite randomised controlled trials. In this paper, we provide the rationale for incorporating MRI and MRS biomarkers into the multisite, phase III high-dose erythropoietin for asphyxia and encephalopathy (HEAL) Trial, the MRI/S protocol and describe the strategies used for harmonisation across multiple MRI platforms. Methods and analysis: Neonates with moderate or severe encephalopathy enrolled in the multisite HEAL trial undergo MRI and MRS between 96 and 144 hours of age using standardised neuroimaging protocols. MRI and MRS data are processed centrally and used to determine a brain injury score and quantitative measures of lactate and n-acetylaspartate. Harmonisation is achieved through standardisation-thereby reducing intrasite and intersite variance, real-time quality assurance monitoring and phantom scans. Ethics and dissemination: IRB approval was obtained at each participating site and written consent obtained from parents prior to participation in HEAL. Additional oversight is provided by an National Institutes of Health-appointed data safety monitoring board and medical monitor

GAMMA-IRRADIATION REDUCES SURVIVORSHIP, FEEDING BEHAVIOR, and OVIPOSITION of FEMALE AEDES AEGYPTI

Aedes aegypti is a prominent disease vector that is difficult to control through traditional integrated vector management due to its cryptic peridomestic immature-stage habitat and adult resting behavior, increasing resistance to pesticide formulations approved by the US Environmental Protection Agency, escalating deregistration of approved pesticides, and slow development of new effective chemical control measures. One novel method to control Ae. aegypti is the sterile insect technique (SIT) that leverages the mass release of irradiated (sterilized) males to overwhelm mate choice of natural populations of females. However, one potential liability of SIT is sex sorting errors prior to irradiation, resulting in accidental release of females. Our goal in this study was to test the extent to which irradiation affects female life-history parameters to assess the potential impacts of releasing irradiated females accidentally sorted with males. In this study, we determined that a radiation dose ≥30 Gy—a dose sufficient to sterilize males while preserving their mating competitiveness—may substantially impact longevity, bloodfeeding, oviposition, and egg hatch rate of female Ae. aegypti after being irradiated as pupae. These findings could reduce public concern for accidental release of females alongside irradiated males in an operational Ae. aegypti SIT control program