The JPL MSAT mobile laboratory and the pilot field experiments

A Mobile Laboratory/Propagation Measurement Van (PMV) was developed to support the field experiments of the Mobile Satellite Experiment (MSAT-X) Project. This van was designed to provide flexibility, self-sufficiency and data acquisition to allow for both measurement of equipment performance and the mobile environment. The design philosophy and implementation of the PMV are described. The Pilot Field Experiments and an overall description of the three experiments in which the PMV was used are described

Collective Activity Bursting in a Population of Excitable Units Adaptively Coupled to a Pool of Resources

We study the collective dynamics in a population of excitable units (neurons) adaptively interacting with a pool of resources. The resource pool is influenced by the average activity of the population, whereas the feedback from the resources to the population is comprised of components acting homogeneously or inhomogeneously on individual units of the population. Moreover, the resource pool dynamics is assumed to be slow and has an oscillatory degree of freedom. We show that the feedback loop between the population and the resources can give rise to collective activity bursting in the population. To explain the mechanisms behind this emergent phenomenon, we combine the Ott-Antonsen reduction for the collective dynamics of the population and singular perturbation theory to obtain a reduced system describing the interaction between the population mean field and the resources.Peer Reviewe

An exploratory study of co-location as a factor in synchronous, collaborative medical informatics distance education

<p>Abstract</p> <p>Background</p> <p>This study determined differences in learning, judgments of teaching and technology, and interaction when videoconferencing was used to deliver instruction on telemedicine to medical students in conditions where they were co-located and dispersed. A lecture on telemedicine was given by videoconference to medical students at a distant site. After a question and answer period, students were then given search problems on the topic and encouraged to collaborate. Half the students were randomly assigned to a co-located condition where they received the presentation and collaborated in a computer lab, and half were assigned to a dispersed condition where they were located in different rooms to receive the presentation and collaborate online using the videoconferencing technology. Students were observed in both conditions and they individually completed a test on presentation content and a rating scale about the quality of the teaching and the technology.</p> <p>Findings</p> <p>There were no differences between the two groups in the learning outcomes or judgments about the teaching and technology, with the exception that more students in the dispersed condition felt more interaction was fostered. The level and patterns of interaction were very different in the two conditions and higher for dispersed students.</p> <p>Conclusions</p> <p>Synchronous communication at a distance via videoconference may give sufficient sense of presence that the learning experience may be similar to that in actual classrooms, even when students are far apart. The technology may channel interaction in desirable ways.</p

Follow-up of 2003 Human West Nile Virus Infections, Denver, Colorado

Tri-County Health Department and Boulder County Public Health conducted a follow-up study of all nonfatal West Nile virus (WNV) cases reported during 2003 in 4 metropolitan Denver, Colorado, counties. Self-reported patient information was obtained ≈6 months after onset. A total of 656 (81.2%) eligible WNV patients are included in this study

Forest Composition Change and Biophysical Climate Feedbacks Across Boreal North America

Deciduous tree cover is expected to increase in North American boreal forests with climate warming and wildfire. This shift in composition has the potential to generate biophysical cooling via increased land surface albedo. Here we use Landsat-derived maps of continuous tree canopy cover and deciduous fractional composition to assess albedo change over recent decades. We find, on average, a small net decrease in deciduous fraction from 2000 to 2015 across boreal North America and from 1992 to 2015 across Canada, despite extensive fire disturbance that locally increased deciduous vegetation. We further find near-neutral net biophysical change in radiative forcing associated with albedo when aggregated across the domain. Thus, while there have been widespread changes in forest composition over the past several decades, the net changes in composition and associated post-fire radiative forcing have not induced systematic negative feedbacks to climate warming over the spatial and temporal scope of our study

DPP6 regulation of dendritic morphogenesis impacts hippocampal synaptic development

Dipeptidyl-peptidase 6 is an auxiliary subunit of Kv4-mediated A-type K+ channels that, in addition to enhancing channel surface expression, potently accelerates their kinetics. The dipeptidyl-peptidase 6 gene has been associated with a number of human central nervous system disorders including autism spectrum disorders and schizophrenia. Here we employ knockdown and genetic deletion of dipeptidyl-peptidase 6 to reveal its importance for the formation and stability of dendritic filopodia during early neuronal development. We find that the hippocampal neurons lacking dipeptidyl-peptidase 6 show a sparser dendritic branching pattern along with fewer spines throughout development and into adulthood. In electrophysiological and imaging experiments, we show that these deficits lead to fewer functional synapses and occur independently of the potassium channel subunit Kv4.2. We report that dipeptidyl-peptidase 6 interacts with a filopodia-associated myosin as well as with fibronectin in the extracellular matrix. dipeptidyl-peptidase 6 therefore has an unexpected but important role in cell adhesion and motility, impacting the hippocampal synaptic development and function