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Drought-driven humanitarian emergencies are becoming more frequent in the Horn of Africa where millions of people in this arid region face chronic water and food insecurity. Evidence from the region shows increasing reliance on groundwater supplies, infrastructure and institutional systems in response to decreasing rainfall. Drought emergencies can be mitigated by investing in resilience efforts that make safe water reliably available at strategic groundwater abstraction locations during cycles of water stress. A combination of early warning data, policy reform, asset management and improved rural water supplies and maintenance may enable rapid, responsive, and accountable water governance that is more cost effective than emergency relief and better positioned to absorb and adapt to shocks.

The cost-effectiveness and reliability of waste collection services in informal settlements can be difficult to optimize given the geospatial and temporal variability of latrine use. Daily servicing to avoid overflow events is inefficient, but dynamic scheduling of latrine servicing could reduce costs by providing just-in-time servicing for latrines. This study used cellular-connected motion sensors and machine learning to dynamically predict when daily latrine servicing could be skipped with a low risk of overflow. Sensors monitored daily latrine activity, and enumerators collected solid and liquid waste weight data. Given the complex relationship between latrine use and the need for servicing, an ensemble machine learning algorithm (Super Learner) was used to estimate waste weights and predict overflow events to facilitate dynamic scheduling. Accuracy of waste weight predictions based on sensor and historical weight data was adequate for estimating latrine fill levels (mean error of 20% and 22% for solid and liquid wastes), but there was greater accuracy in predicting overflow events (area under the receiver operating characteristic curve of 0.90). Although our simulations indicate that dynamic scheduling could substantially reduce costs for lower use latrines, we found that cost reduction was more modest for higher use latrines and that there was a significant gap between the simulated and implemented results.

Millions of people in the arid regions of Kenya and Ethiopia face water scarcity and frequent drought. Water resource forecasting and reliable operation of groundwater distribution systems may improve drought resilience. In this study, we examined three remote sensing data sets against in-situ sensor-collected groundwater extraction data from 221 water points serving over 1.34 million people across northern Kenya and Afar, Ethiopia between January 1, 2017 and August 31, 2018. In models containing rainfall as a binary variable, we observed an overall 23% increase in borehole runtime following weeks with no rainfall compared to weeks preceded by some rainfall. Further, a 1 mm increase in rainfall was associated with a 1% decrease in borehole use the following week. When surface water availability is reduced during the dry seasons, groundwater demand increases. Our findings emphasize the imperative to maintain functionality of groundwater boreholes in these regions which often suffer drought related emergencies. Funding provided by the United States Agency for International Development, the World Bank, the National Science Foundation, and the Cisco Foundation. The views expressed in this article do not necessarily reflect the views of the United States Agency for International Development or the United States Government.

Sustainable access to safe drinking water protects against infectious disease and promotes overall health. Despite considerable progress toward increasing water access, safe water quality and reliable service delivery remain a challenge. Traditional financing strategies pay implementers based on inputs and activities, with minimal incentives for water quality monitoring and sustained service operation. Pay-for-performance offers an alternative financing strategy that delivers all or a portion of payment based on performance indicators of desired outputs or outcomes. A pay-for-performance approach in the water sector could quantify and incentivize health impact. Averted disability-adjusted life years (ADALYs) have been used as a performance indicator to measure the burden of disease averted due to environmental health interventions. Water-related disease burden can be measured for application as an ADALYs performance indicator following either comparative risk assessment or quantitative microbial risk assessment. Comparative risk assessment models disease burden using water source type as a proxy indicator of microbial water quality, while quantitative microbial risk assessment models disease burden using concentrations of indicator pathogens. This paper compares these risk assessment methodologies, and summarizes the limitations of applying these approaches toward quantifying ADALYs as a performance indicator for water quality interventions.

We investigated the effects of multiple planning factors on normal brain dose for single-isocenter VMAT stereotactic radiosurgery (SRS). Ten patients were retrospectively planned using a standardized objective function and all 16 combinations of 2 versus 4 arcs, collimator angle 45° versus selected per beam to minimize area of normal brain exposed in the beams-eye-view, fixed jaw versus following the trailing MLC leaf, and a 2 Gy mean dose objective for healthy brain versus no low dose objective. Limiting the normal brain mean dose in the optimization objective function significantly reduced the low dose spill into the normal brain without changing target coverage. Jaw tracking and appropriate selection of collimator also reduced the low dose volume, but to a lesser extent. To reduce low dose spill into normal brain for single isocenter VMAT radiosurgery of multiple targets, it is important to incorporate a limit on low dose spill into the objective function. This study has implications beyond single-isocenter VMAT radiosurgery. When comparing different inverse-planned treatment techniques, metrics that are important for evaluation of plan quality must be included the objective function.

In this chapter, the reader will find a comprehensive overview of important principles and concepts to linac-based stereotactic radiosurgery and hypofractionated stereotactic radiotherapy, as well as the indications for each. These include history of radiosurgery and linac-based radiosurgery to put the contents of the chapter in context, as well as a brief introduction to concepts and metrics used to evaluate the quality of radiosurgery treatment plans and techniques to produce high-quality radiosurgery plans.

In rural sub-Saharan Africa, where handpumps are common, 10-67% are nonfunctional at any one time, and many never get repaired. Increased reliability requires improved monitoring and responsiveness of maintenance providers. In 2014, 181 cellular enabled water pump use sensors were installed in three provinces of Rwanda. In three arms, the nominal maintenance model was compared against a "best practice" circuit rider model, and an "ambulance" service model. In only the ambulance model was the sensor data available to the implementer, and used to dispatch technicians. The study ran for seven months in 2014-2015. In the study period, the nominal maintenance group had a median time to successful repair of approximately 152 days, with a mean per-pump functionality of about 68%. In the circuit rider group, the median time to successful repair was nearly 57 days, with a per-pump functionality mean of nearly 73%. In the ambulance service group, the successful repair interval was nearly 21 days with a functionality mean of nearly 91%. An indicative cost analysis suggests that the cost per functional pump per year is approximately similar between the three models. However, the benefits of reliable water service may justify greater focus on servicing models over installation models.

This work presents a custom, high-throughput combinatorial approach for the optimization of thermoelectric thin films consisting of materials with complex chemistry and structures (e.g., the layered misfit cobaltite, Ca 3 Fe x Co 4−x O 9 ). Combinatorial thin films with graded compositions are produced on 100 mm Si wafers from multiple target materials using pulsed laser deposition. Film thickness and composition are mapped as a function of wafer location. Crystal structures are determined using x–y mapping XRD analysis with specially designed algorithms for automated peak location and analysis. Thermoelectric properties, specifically the Seebeck coefficient and the electrical resistivity, are screened using a custom designed automated probe system. By combining the rapid synthesis of many compositions and structures simultaneously using combinatorial deposition and automated analytical tools capable of spatial mapping, trends in material performance are shown to be quickly obtained primarily due to the elimination of one-at-a-time synthesis and analysis. The possible approaches for such complex multivalent combinatorial optimization of thin films are identified and discussed. For the Ca 3 Fe x Co 4−x O 9 system presented, variations to the thermoelectric power factor are dominated by changes in the electrical resistivity. Enhancements to the Seebeck coefficient are observed due to the incorporation of Fe into the Ca 3 Fe x Co 4−x O 9 structure; however, this improvement is overshadowed by increases in the electrical resistivity due to variations in film thickness and the presence of secondary phases (Co 3 O 4 and Ca 2 Fe 2 O 5 ) which result from increasing Fe content and off-axis pulsed laser deposition.

This study examined the composition and ecology of benthic algal communities within two streams of the Colorado Rocky Mountains. Algal community samples as well as physical and chemical habitat parameters were collected from Boulder Creek and St. Vrain Creek between July and August, 2013. Sampling began in the high elevation montane headwaters for each stream and continued downstream to the low elevation plains locations with a total of 41 samples collected. Algal communities from each stream were dominated by diatoms. Algal cell densities and species diversity were highly variable within each stream, and there was no difference in overall cell density or species diversity between the streams. Despite the close proximity of Boulder Creek and St. Vrain Creek, differences in algal community composition were found between the two streams. Differences in the algal communities between the two streams were found to be a result of higher conductivity, temperature, and pH and increased levels of total nitrogen in Boulder Creek compared to St. Vrain Creek.

Rhoicosphenia is a relatively small genus with about 30 species and 30 infraspecific varieties. Over the past decade there has been a renewed interest in describing previously undocumented diversity in Europe, Asia and North America, from fossil and extant material, and from marine and freshwater environments. Of the ca. 60 Rhoicosphenia taxa, one species, R. lesothensis, has already been transferred out of the genus. During a literature review of the genus, a passage by Hustedt suggesting the need to transfer another species, R. vanheurckii, out of the genus was examined. Our morphological investigations result in the transfer of R. vanheurckii to the genus Planothidium. Although this diatom does not bear the cavum or sinus typical of most Planothidium species, it fits with the other characters of the genus and will retain the specific epithet, as P. vanheurckii (Grunow) E.W. Thomas, Van de Vijver & Kociolek comb. nov.

Ion drag is known to play an important role in driving neutral thermosphere circulation at auroral latitudes, especially during the main phase of geomagnetic storms. During the recovery phase, the neutrals are known to drive the ions and generate ionospheric electric fields and currents via the disturbance dynamo mechanism. At mid-latitudes, the precise interplay between ions and neutrals is less understood largely because of the paucity of measurements that have been available. In this work, weinvestigate ion-neutral coupling at middle latitudes using co-located ion drift velocity measurements obtained from SuperDARN radars and neutral wind velocity and temperature measurements obtained from the NATION Fabry-Perot interferometers. We examine one recent storm period on October 2-3, 2013 during both the main phase and late recovery phase. By using ion-neutral momentum exchange theory and a time-lagged correlation analysis, we analyze the coupling timescales and dominant driving mechanisms. We observe that during the main phase the neutrals respond to the ion convection on a timescale of ∼ 84 minutes which is significantly faster than what would be expected from local ion-drag momentum forcing alone. This suggests other storm time influences are important for driving the neutrals during the main phase, such as Joule heating. During the late recovery phase, the neutrals are observed to drive the ion convection without any significant time delay, consistent with the so-called “neutral fly wheel effect" or disturbance dynamo persisting well into the late recovery phase.

Transionospheric radio signals in the high-latitude polar cap are susceptible to degradation when encountering sharp electron density gradients associated with discrete plasma structures, or patches. Multi-instrument measurements of polar cap patches are examined during a geomagnetic storm interval on 22 January 2012. For the first time, we monitor the transportation of patches with high spatial and temporal resolution across the polar cap for 1–2 h using a combination of GPS total electron content (TEC), all-sky airglow imagers (ASIs), and Super Dual Auroral Radar Network (SuperDARN) HF radar backscatter. Simultaneous measurements from these data sets allow for continuous tracking of patch location, horizontal extent, and velocity despite adverse observational conditions for the primary technique (e.g., sunlit regions in the ASI data). Spatial collocation between patch-like features in relatively coarse but global GPS TEC measurements and those mapped by high-resolution ASI data was very good, indicating that GPS TEC can be applied to track patches continuously as they are transported across the polar cap. In contrast to previous observations of cigar-shaped patches formed under weakly disturbed conditions, the relatively narrow dawn-dusk extent of patches in the present interval (500–800 km) suggests association with a longitudinally confined plasma source region, such as storm-enhanced density (SED) plume. SuperDARN observations show that the backscatter power enhancements corresponded to the optical patches, and for the first time we demonstrate that the motion of the optical patches was consistent with background plasma convection velocities.

Previous investigations of ionospheric storm-enhanced density (SED) and tongue of ionization (TOI) focused mostly on the behavior of TOI during intense geomagnetic storms. Little attention has been paid to the spatial and temporal variations of TOI during weak to moderate geomagnetic disturbed conditions. In this paper we investigate the source and development of TOI during a moderate geomagnetic storm on 14 October 2012. Multi-instrumental observations including GPS total electron content (TEC), Defense Meteorological Satellite Program (DMSP) in situ measured total ion concentration and ion drift velocity, SuperDARN measured polar ion convection patterns, and electron density profiles from the Poker Flat Incoherent Scatter Radar (PFISR) have been utilized in the current analysis. GPS TEC maps show salient TOI structures persisting for about 5 h over high latitudes of North America on 14 October 2012 in the later recovery phase of the storm when the magnitudes of IMF By and Bz were less than 5 nT. The PFISR electron density profiles indicate that the extra ionization for TEC enhancements mainly occurred in the topside ionosphere with no obvious changes in the bottomside ionosphere and vertical plasma drifts. Additionally, there were no signatures of penetration electric fields in the equatorial electrojet data and upward ion drifts at high latitudes. At the same time, strong subauroral polarization streams with ion drift speeds exceeding 2.5 km/s carried sunward fluxes and migrated toward lower latitudes for about 5° based on the DMSP cross-track drift measurements. Based on those measurements, we postulate that the combined effects of initial build-up of ionization at midlatitudes through daytime production of ionization and equatorward (or less poleward than normal daytime) neutral wind reducing downward diffusion along the inclined filed lines, and an expanded polar ion convection pattern and its associated horizontal plasma transport are important in the formation of the TOI.

This paper advances research on methods used to evaluate sanitation usage and behavior. The research used quantitative and qualitative methods to contribute to new understanding of sanitation practices and meanings in rural India. We estimated latrine usage behavior through ethnographic interviews and sensor monitoring, specifically the latest generation of infrared toilet sensors, Portland State University Passive Latrine Use Monitors (PLUMs). Two hundred and fifty-eight rural households in West Bengal (WB) and Himachal Pradesh, India, participated in the study by allowing PLUMs to be installed in their houses for a minimum of 6 days. Six hundred interviews were taken in these households, and in others, where sensors had not been installed. Ethnographic and observational methods were used to capture the different defecation habits and their meanings in the two study sites. Those data framed the analysis of the PLUM raw data for each location. PLUMs provided reliable, quantitative verification. Interviews elicited unique information and proved essential to understanding and maximizing the PLUM data set. The combined methodological approach produced key findings that latrines in rural WB were used only for defecation, and that low cost, pit latrines were being used sustainably in both study areas.

Spacecraft observations of boundary waves at the dayside terrestrial magnetopause and their ground-based signatures are presented. Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft measured boundary waves at the magnetopause while ground-based HF radar measured corresponding signatures in the ionosphere indicating a large-scale response and tailward propagating waves. The properties of the oscillations are consistent with linear phase Kelvin-Helmholtz waves along the magnetopause boundary. During this time period multiple THEMIS spacecraft also measured a plasmaspheric plume contacting the local magnetopause and mass loading the boundary. Previous work has demonstrated that increasing the density at the magnetopause can lower the efficiency of reconnection. Extending this further, present observations suggest that a plume can modulate instability processes such as the Kelvin-Helmholtz instability and allow them to form closer to the subsolar point along the magnetopause than without a plume. The current THEMIS observations from 21 September 2010 are consistent with a theory which predicts that increasing the density at the boundary will lower the Kelvin-Helmholtz threshold and allow waves to form for a lower velocity shear.

During the ascending phase of solar cycle 24, a series of interplanetary coronal mass ejections (ICMEs) in the period 7-17 March 2012 caused geomagnetic storms that strongly affected high-latitude ionosphere in the Northern and Southern Hemisphere. GPS phase scintillation was observed at northern and southern high latitudes by arrays of GPS ionospheric scintillation and TEC monitors (GISTMs) and geodetic-quality GPS receivers sampling at 1 Hz. Mapped as a function of magnetic latitude and magnetic local time (MLT), the scintillation was observed in the ionospheric cusp, the tongue of ionization fragmented into patches, sun-aligned arcs in the polar cap, and nightside auroral oval and subauroral latitudes. Complementing a companion paper (Prikryl et al., 2015a) that focuses on the high-latitude ionospheric response to variable solar wind in the North American sector, interhemispheric comparison reveals commonalities as well as differences and asymmetries between the northern and southern high latitudes, as a consequence of the coupling between the solar wind and magnetosphere. The interhemispheric asymmetries are caused by the dawn-dusk component of the interplanetary magnetic field controlling the MLT of the cusp entry of the storm-enhanced density plasma into the polar cap and the orientation relative to the noon-midnight meridian of the tongue of ionization. Canada Foundation for InnovationCanada Foundation for Innovation; New Brunswick Innovation Foundation; National Science FoundationNational Science Foundation (NSF) [PLR-1248062]; NSFNational Science Foundation (NSF) [AGS-0838219, AGS-0946900]; national scientific funding agency of Australia; national scientific funding agency of Canada; national scientific funding agency of China; national scientific funding agency of France; national scientific funding agency of Japan; national scientific funding agency of South Africa; national scientific funding agency of United Kingdom; national scientific funding agency of United States of America; Natural Resources Canada, Earth Sciences Sector (NRCan ESS)Natural Resources Canada [20140371]; Engineering and Physical Sciences Research CouncilEngineering & Physical Sciences Research Council (EPSRC) [EP/H003479/1, EP/E007902/1, EP/H003304/1, TS/G002592/1]; Natural Environment Research CouncilNERC Natural Environment Research Council [NE/F015321/1]; Science and Technology Facilities CouncilScience & Technology Facilities Council (STFC) [ST/H003770/1, PP/D002230/1] Infrastructure funding for CHAIN was provided by the Canada Foundation for Innovation and the New Brunswick Innovation Foundation. CHAIN and CGSM operation is conducted in collaboration with the Canadian Space Agency (CSA). The infrastructure for the GISTM at SANAE was provided by the South African National Antarctic Programme. The GISTM of southern auroral oval station Macquarie Island is operated by the Australian Bureau of Meteorology. Siena College gratefully acknowledges support from the National Science Foundation under award PLR-1248062. The Virginia Tech authors acknowledge the support through NSF awards AGS-0838219 and AGS-0946900. The authors acknowledge the use of SuperDARN data. SuperDARN is a collection of radars funded by national scientific funding agencies of Australia, Canada, China, France, Japan, South Africa, the United Kingdom and the United States of America. The DMSP particle detectors were designed by Dave Hardy of the Air Force Research Laboratory, and the data were obtained from Johns Hopkins University Applied Research Laboratory. The International GNSS Service (IGS) and its contributing organizations, including Denmark Technical University National Space Institute, are thanked for 1 Hz GPS data. This work was supported by the Public Safety Geosciences program of the Natural Resources Canada, Earth Sciences Sector (NRCan ESS contribution number 20140371).

The interval of geomagnetic storms of 7-17 March 2012 was selected at the Climate and Weather of the Sun-Earth System (CAWSES) II Workshop for group study of space weather effects during the ascending phase of solar cycle 24 (Tsurutani et al., 2014). The high-latitude ionospheric response to a series of storms is studied using arrays of GPS receivers, HF radars, ionosondes, riometers, magnetometers, and auroral imagers focusing on GPS phase scintillation. Four geomagnetic storms showed varied responses to solar wind conditions characterized by the interplanetary magnetic field (IMF) and solar wind dynamic pressure. As a function of magnetic latitude and magnetic local time, regions of enhanced scintillation are identified in the context of coupling processes between the solar wind and the magnetosphere-ionosphere system. Large southward IMF and high solar wind dynamic pressure resulted in the strongest scintillation in the nightside auroral oval. Scintillation occurrence was correlated with ground magnetic field perturbations and riometer absorption enhancements, and collocated with mapped auroral emission. During periods of southward IMF, scintillation was also collocated with ionospheric convection in the expanded dawn and dusk cells, with the antisunward convection in the polar cap and with a tongue of ionization fractured into patches. In contrast, large northward IMF combined with a strong solar wind dynamic pressure pulse was followed by scintillation caused by transpolar arcs in the polar cap. Canada Foundation for InnovationCanada Foundation for Innovation; New Brunswick Innovation Foundation; NSFNational Science Foundation (NSF) [AGS-0838219, AGS-0946900]; national scientific funding agency of Australia; national scientific funding agency of Canada; national scientific funding agency of China; national scientific funding agency of France; national scientific funding agency of Japan; national scientific funding agency of South Africa; national scientific funding agency of United Kingdom; national scientific funding agency of United States of America; Natural Resources Canada, Earth Sciences Sector (NRCan ESS)Natural Resources Canada [20140371] Infrastructure funding for CHAIN was provided by the Canada Foundation for Innovation and the New Brunswick Innovation Foundation. CHAIN and CGSM operation is conducted in collaboration with the Canadian Space Agency (CSA). The magnetometer and riometer operation and data processing was supported by the Geomagnetic Laboratory, Natural Resources Canada. The Virginia Tech authors acknowledge the support of NSF awards AGS-0838219 and AGS-0946900. The authors acknowledge the use of SuperDARN data. SuperDARN is a collection of radars funded by national scientific funding agencies of Australia, Canada, China, France, Japan, South Africa, the United Kingdom, and the United States of America. The DMSP particle detectors were designed by Dave Hardy of the Air Force Research Laboratory, and the data were obtained from Johns Hopkins University Applied Research Laboratory. The International GNSS Service (IGS) and its contributing organizations, including Denmark Technical University National Space Institute, are thanked for 1 Hz GPS data. We acknowledge use of NASA/GSFC's Space Physics Data Facility's OMNIWeb and CDAWeb service as well as OMNI data. We acknowledge contributions of the ACE, Geotail and Wind teams. This work was supported by the Public Safety Geosciences program of the Natural Resources Canada, Earth Sciences Sector (NRCan ESS contribution number 20140371).

The new 2030 Agenda for Sustainable Development includes water, sanitation, and hygiene (WASH) at its core. A dedicated Sustainable Development Goal (SDG 6) declares a commitment to “ensure availability and sustainable management of water and sanitation for all.” Monitoring progress toward this goal will be challenging: direct measures of water and sanitation service quality and use are either expensive or elusive. However, reliance on household surveys poses limitations and likely overstated progress during the Millennium Development Goal period. In Innovations in WASH Impact Measures: Water and Sanitation Measurement Technologies and Practices to Inform the Sustainable Development Goals, we review the landscape of proven and emerging technologies, methods, and approaches that can support and improve on the WASH indicators proposed for SDG target 6.1, “by 2030, achieve universal and equitable access to safe and affordable drinking water for all,” and target 6.2, “by 2030, achieve access to adequate and equitable sanitation and hygiene for all and end open defecation, paying special attention to the needs of women and girls and those in vulnerable situations.” Although some of these technologies and methods are readily available, other promising approaches require further field evaluation and cost reductions. Emergent technologies, methods, and data-sharing platforms are increasingly aligned with program impact monitoring. Improved monitoring of water and sanitation interventions may allow more cost-effective and measurable results. In many cases, technologies and methods allow more complete and impartial data in time to allow program improvements. Of the myriad monitoring and evaluation methods, each has its own advantages and limitations. Surveys, ethnographies, and direct observation give context to more continuous and objective electronic sensor data. Overall, combined methodologies can provide a more comprehensive and instructive depiction of WASH usage and help the international development community measure our progress toward reaching the SDG WASH goals.

TIDs are the large scale electron density perturbations that travel in the ionosphere and can be tracked by number of instruments, like incoherent scatter radar, ionosondes, HF Dopler system etc. They are believed to be the signature of atmospheric gravity wave in the high latitude ionosphere, which are generated due to geomagnetic activities [1].

Interplanetary coronal mass ejections (ICMEs) compounded by high-speed plasma streams from coronal holes caused two intense geomagnetic storms on March 17–18, 2013 and 2015 during the current solar cycle. Ionospheric responses to the storms in the northern and southern hemispheres are compared in the context of solar wind coupling to the magnetosphere-ionosphere system. Phase scintillation is observed at high latitudes by arrays of high-rate GNSS Ionospheric Scintillation and TEC Monitors (GISTMs) and geodetic-quality GPS receivers sampling at 1 Hz. The high-rate GPS receivers are distributed in the northern and in the southern high latitudes with sparser coverage. In addition to GPS receivers, the high-latitude ionosphere dynamics is studied using arrays of ground-based instruments including HF radars, ionosondes, riometers, magnetometers, optical imagers as well as particle detectors and ultraviolet scanning imagers onboard the DMSP satellites.

A facility has been developed to simulate the ablation of micrometeoroids in laboratory conditions. An electrostatic dust accelerator is used to generate iron particles with velocities of 10-70 km/s. The particles are then introduced into a chamber pressurized with a target gas, where the pressure is adjustable between 0.01 and 0.5 Torr, and the particle partially or completely ablates over a short distance. An array of biased electrodes above and below the ablation path is used to collect the generated ions/electrons with a spatial resolution of 2.6 cm along the ablating particles' path, thus allowing the study of the spatiotemporal evolution of the process. For completely ablated particles, the total collected charge directly yields the ionization coefficient of a given dust material-target gas combination. The first results of this facility measured the ionization coefficient of iron atoms with N2, air, CO2, and He target gases for impact velocities >20 km/s, and are reported by Thomas et al. [Geophys. Res. Lett. 43, 3645 (2016)]. The ablation chamber is also equipped with four optical ports that allow for the detection of the light emitted by the ablating particle. A multichannel photomultiplier tube system is used to observe the ablation process with a spatial and temporal resolution of 0.64 cm and 90 ns. The preliminary results indicate that it is possible to calculate the velocity of the ablating particle from the optical observations, and in conjunction with the spatially resolved charge measurements allow for experimental validation of ablation models in future studies.

The use of sanitary inspections combined with periodic water quality testing has been recommended in some cases as screening tools for fecal contamination. We conducted sanitary inspections and tested for thermotolerant coliforms (TTCs), a fecal indicator bacteria, among 7,317 unique water sources in West Bengal, India. Our results indicate that the sanitary inspection score has poor ability to identify TTC-contaminated sources. Among deep and shallow hand pumps, the area under curve (AUC) for prediction of TTC > 0 was 0.58 (95% confidence interval [CI] = 0.53–0.61) and 0.58 (95% CI = 0.54–0.62), respectively, indicating that the sanitary inspection score was only marginally better than chance in discriminating between contaminated and uncontaminated sources of this type. A slightly higher AUC value of 0.64 (95% CI=0.57–0.71) was observed when the sanitary inspection score was used for prediction of TTC > 0 among the gravity-fed piped sources. Among unprotected springs (AUC = 0.48, 95% CI = 0.38–0.55) and unprotected dug wells (AUC = 0.41, 95% CI = 0.20–0.66), the sanitary inspection score performed more poorly than chance in discriminating between sites with TTC < 1 and TTC > 0. Aggregating over all source types, the sensitivity (true positive rate) of a high/very high sanitary inspection score for TTC contamination (TTC > 1 CFU/100 mL) was 29.4% and the specificity (true negative rate) was 77.9%, resulting in substantial misclassification of the sites when using the established risk categories. These findings suggest that sanitary surveys are inappropriate screening tools for identifying TTC contamination at water points.

Broken water pumps continue to impede efforts to deliver clean and economically-viable water to the global poor. The literature has demonstrated that customers’ health benefits and willingness to pay for clean water are best realized when clean water infrastructure performs extremely well (>99% uptime). In this paper, we used sensor data from 42 Afridev-brand handpumps observed for 14 months in western Kenya to demonstrate how sensors and supervised ensemble machine learning could be used to increase total fleet uptime from a best-practices baseline of about 70% to >99%. We accomplish this increase in uptime by forecasting pump failures and identifying existing failures very quickly. Comparing the costs of operating the pump per functional year over a lifetime of 10 years, we estimate that implementing this algorithm would save 7% on the levelized cost of water relative to a sensor-less scheduled maintenance program. Combined with a rigorous system for dispatching maintenance personnel, implementing this algorithm in a real-world program could significantly improve health outcomes and customers’ willingness to pay for water services.

Rhoicosphenia Grunow is a common diatom in both freshwater and marine ecosystems and the genus can be found on nearly every continent. Most of the currently described taxa are extant and only six of 58 taxa are known from the fossil record. Also, reports from freshwater habitats of the Indian subcontinent are rare, with one report of Rhoicosphenia marina from marine ecosystems. Rhoicosphenia is common in freshwater and marine ecosystems of the USA and three fossils have been described from the Pacific Northwest. Four new species of Rhoicosphenia are described from fossil deposits in Gujarat, India and Oregon, USA. The new species from India are R. gandhii, a large, coarsely ornamented species and R. indica, a smaller species, both found in the same fossil deposit. The species from Oregon are R. reimeri, another large taxon, as well as R. patrickae, another small species, and both are found in the same fossil deposit. These new species descriptions highlight the recent trend of discovery of Rhoicosphenia d...

Background Volumetric modulated arc therapy (VMAT) has been shown feasible for radiosurgical treatment of multiple cranial lesions with a single isocenter.

Storm-enhanced density (SED) plumes are prominent ionospheric electron density increases at the dayside middle and high latitudes. The generation and decay mechanisms of the plumes are still not clear. We present observations of SED plumes during six storms between 2010 and 2013 and comprehensively analyze the associated ionospheric parameters within the plumes, including vertical ion flow, field-aligned ion flow and flux, plasma temperature, and field-aligned currents, obtained from multiple instruments, including GPS total electron content (TEC), Poker Flat Incoherent Scatter Radar (PFISR), Super Dual Auroral Radar Network, and Active Magnetosphere and Planetary Electrodynamics Response Experiment. The TEC increase within the SED plumes at the PFISR site can be 1.4–5.5 times their quiet time value. The plumes are usually associated with northwestward E × B flows ranging from a couple of hundred m s−1 to > 1 km s−1. Upward vertical flows due to the projection of these E × B drifts are mainly responsible for lifting the plasma in sunlit regions to higher altitude and thus leading to plume density enhancement. The upward vertical flows near the poleward part of the plumes are more persistent, while those near the equatorward part are more patchy. In addition, the plumes can be collocated with either upward or downward field-aligned currents (FACs) but are usually observed equatorward of the peak of the Region 1 upward FAC, suggesting that the northwestward flows collocated with plumes can be either subauroral or auroral flows. Furthermore, during the decay phase of the plume, large downward ion flows, as large as ~200 m s−1, and downward fluxes, as large as 1014 m−2 s−1, are often observed within the plumes. In our study of six storms, enhanced ambipolar diffusion due to an elevated pressure gradient is able to explain two of the four large downward flow/flux cases, but this mechanism is not sufficient for the other two cases where the flows are of larger magnitude. For the latter two cases, enhanced poleward thermospheric wind is suggested to be another mechanism for pushing the plasma downward along the field line. These downward flows should be an important mechanism for the decay of the SED plumes.

In excitatory neurons, SCN2A (NaV1.2) and SCN8A (NaV1.6) sodium channels are enriched at the axon initial segment. NaV1.6 is implicated in several mouse models of absence epilepsy, including a missense mutation identified in a chemical mutagenesis screen (Scn8a(V929F)). Here, we confirmed the prior suggestion that Scn8a(V929F) exhibits a striking genetic background-dependent difference in phenotypic severity, observing that spike-wave discharge (SWD) incidence and severity are significantly diminished when Scn8a(V929F) is fully placed onto the C57BL/6J strain compared with C3H. Examination of sequence differences in NaV subunits between these two inbred strains suggested NaV1.2(V752F) as a potential source of this modifier effect. Recognising that the spatial co-localisation of the NaV channels at the axon initial segment (AIS) provides a plausible mechanism for functional interaction, we tested this idea by undertaking biophysical characterisation of the variant NaV channels and by computer modelling. NaV1.2(V752F) functional analysis revealed an overall gain-of-function and for NaV1.6(V929F) revealed an overall loss-of-function. A biophysically realistic computer model was used to test the idea that interaction between these variant channels at the AIS contributes to the strain background effect. Surprisingly this modelling showed that neuronal excitability is dominated by the properties of NaV1.2(V752F) due to "functional silencing" of NaV1.6(V929F) suggesting that these variants do not directly interact. Consequent genetic mapping of the major strain modifier to Chr 7, and not Chr 2 where Scn2a maps, supported this biophysical prediction. While a NaV1.6(V929F) loss of function clearly underlies absence seizures in this mouse model, the strain background effect is apparently not due to an otherwise tempting Scn2a variant, highlighting the value of combining physiology and genetics to inform and direct each other when interrogating genetic complex traits such as absence epilepsy.

Several approaches have been proposed in the literature supporting product design applied in low-income settings. These approaches have typically focused on individual- and household-level beneficiaries, with an emphasis on participatory, human-centered co-design methods. In this paper, we present a design approach that is, in contrast, focused on supporting providers of improved water, sanitation, and energy services. We establish requirements for design in these contexts, especially addressing design iteration. We describe sets of feedback systems between designers and various sources of expert knowledge, codifying roles of design stakeholders in this context. We demonstrate these principles across three case studies: a sanitation service monitoring technology in Kenya, a water flowmeter technology in Kenya, and a water storage monitoring technology in Sierra Leone.

Morphological features of the quiet/disturbed time variations in the Total Electron Content (TEC) at the polar cusp station Bharati (76.69°S MLAT) during a period of 5 years starting from February 2013 to December 2017 has been studied using GPS TEC measurements. The TEC at Bharati follows a diurnal pattern with its peak appearing close to local noon/magnetic noon during the summer/winter months. A nighttime enhancement in the TEC is seen around the magnetic midnight during winter. The plasma density at Bharati also exhibits semi-annual variation and a strong dependence on solar activity. A comparison of the IRI 2016 model derived TEC and the GPS TEC at Bharati shows significant differences with large underestimation of TEC especially during the nighttime period of the winter months. A two fold difference in magnitude between the GPS and modeled TEC is also observed in the summer months of the high solar activity period of 2013–2015. The response of the TEC to geomagnetic storms is found to depend on the onset time of the storm. We show that the morphological features in the temporal evolution of the plasma density at Bharati vary as the location of Bharati changes from being inside the polar cap, to the auroral region, and to the polar cusp in quick succession in a day. Our results highlight the fact that the dynamic nature of the location of Bharati with respect to the position of the polar cap plays an important role in deciding the plasma distribution at the polar cusp station.

BACKGROUND: Current standard of care (SOC) management of the brain differs between non-small cell lung cancer (NSCLC) & small cell lung cancer (SCLC). For SCLC, WBRT is considered SOC, even for solitary metastasis. In the setting of no-known metastases, prophylactic cranial irradiation (PCI) is considered SOC. SRS is occasionally utilized in SCLC, e.g. in setting of limited metastasis after WBRT/PCI, or limited metastasis after excellent systemic response to extracranial therapy, or if patient declines WBRT. In this study, we sought to understand more about the nature and outcomes of patients with SCLC who received intracranial SRS at our institution. METHODS: We reviewed radiosurgery treatments from 2005 thru 2019 for patients with SCLC who received SRS. Variables included were: time interval between diagnosis/SRS and death, prior WBRT/ PCI, number of targets, performance status, modality (GK or linac), prior surgery, and available follow-up. RESULTS: We identified 92 SRS treatments among 74 patients. 30 received upfront SRS, the remainder as post-WBRT/PCI salvage. Median survival after initial diagnosis was 22.0 months (min = 6.6, max 55.4). Median survival after first SRS was 6.1 months (min = 0.5, max = 40.4). Median recorded KPS was 75.6. Mean number of mets treated was 3.4 (min = 1, max = 12). Prescription dose range was 12 to 20Gy in single fraction, and 25 to 30Gy in five fraction treatment. 53 treatments were performed on Gamma Knife, 37 with linear accelerator. Four patients were treated post-operatively, one patient was treated pre-operatively. CONCLUSIONS: Survival in our cohort of SCLC patients receiving intracranial SRS compared favorably with historical SCLC controls (8-13mo after dx). Future work will seek to clarify whether there is a difference in brain metastasis velocity between patients treated with upfront PCI/WBRT or SRS, and also seek to address the minimum necessary dose to control SCLC metastases.

INTRODUCTION: Postoperative stereotactic radiosurgery (postop SRS) is potentially complicated by difficulty defining the target volume and the risk of leptomeningeal seeding at the time of surgery. It is hypothesized that preop SRS may render cells less viable to disseminate in the leptomeningeal space. This retrospective study compares the leptomeningeal dissemination (LMD) rate for preop versus postop radiosurgery METHODS: We identified 140 patients with brain metastases who underwent resection and radiosurgery at the University of Alabama at Birmingham including 91 postop patients (2005–2015) and 49 preop patients (2011–2018). The preop group included 19 patients enrolled in a phase I trial of preoperative radiosurgery (12–15 Gy) for tumors 2–6 cm in greatest diameter. In that study 15 Gy was found to be safe in the preop setting but further escalation was not attempted. An additional 30 patients received preop SRS off-study (median dose 15 Gy). The median postop dose was 16 Gy. LMD recurrence was defined as focal pachymeningeal or diffuse leptomeningeal enhancement of the brain, spinal cord, or cauda equina, dural enhancement beyond 5 mm from the index metastasis, subependymal enhancement, or enhancement of cranial nerves. This definition is not limited to carcinomatosis. All events were categorized and confirmed by at least two physicians. RESULTS: 40/140 (29%) patients developed new focal or diffuse LMD. Preop SRS was associated with a higher freedom from leptomeningeal recurrence (84% vs 60% at one year, p=0.021 Breslow, p=0.128 log-rank). Since later LMD may not be related to surgery, a second analysis censoring follow-up at one year was performed and confirmed this trend (p=0.008 Breslow, p=0.014 log-rank). CONCLUSIONS: Preoperative SRS is associated with a reduction in the risk of LMD compared to postop SRS. Focal pachymeningeal dissemination may not always be recognized as related to surgery. A randomized trial of preop vs postop SRS is warranted.

Lisocabtagene maraleucel (liso-cel) is an investigational drug product composed of autologous CD8+ and CD4+ T cells expressing a CD19-specific chimeric antigen receptor (CAR), being evaluated in clinical trials for treatment of B cell malignancies. The CELMoD CC-122 is being evaluated in non-Hodgkin lymphoma (NHL) and can augment T cell function through Cereblon-mediated degradation of Ikaros and Aiolos. Combination approaches aimed at enhancing CAR T cell function may increase the rate, depth, and durability of clinical responses. Here we report pre-clinical results supporting the potential combination of CC-122 an liso-cel. To determine potentiating effects of CC-122 following acute activation (anti-idiotypic Ab or CD19+ targets), T cells expressing the CAR of liso-cel were cultured with CC-122 and assessed for intracellular signaling, cytolytic activity, cytokine production, and activation marker expression. CC-122 significantly increased NFκB, Nur77, and STAT5 as well as effector cytokine production and activation marker expression. Activation-induced exhaustion of CAR T may decrease durable responses in patients. We developed a chronic stimulation assay to render CAR T cells hypofunctional (reduced cytolysis and IL-2 secretion) and examined whether enhanced activation mediated by CC-122 would exhaust the CD19-directed CAR T cells more rapidly. CC-122 was added in one of two regimens: during chronic stimulation (“concurrent”) or during re-challenge (“rescue”). Effects on exhaustion in “concurrent” or “rescue” cultures were evaluated, including by RNAseq and measuring of effector function in re-challenge assays with CD19+ targets. Surprisingly, “concurrent” CC-122 partially reversed a gene signature associated with CAR T cell hypofunctionality and preserved more effector function relative to controls. In “rescue” assays, CC-122 dose-dependently increased cytokine production and restored cytolytic function of exhausted CAR T cells upon re-challenge with CD19+ tumor spheroids. In a disseminated tumor xenograft model, concurrent or delayed dosing of CC-122, in combination with two sub-curative doses of liso-cel, significantly increased median survival by 30 to 40 days. In some cases, survival endpoints were not reached with the combination. Taken together, CC-122 treatment of CD19-directed CAR T cells was shown to enhance CAR T activation in acute stimulation assays; limit CAR T exhaustion onset during chronic stimulation as assessed by gene expression; and reverse an exhausted, hypofunctional CAR T state induced by chronic stimulation. The data suggest that liso-cel pharmacologic activity may both be enhanced and extended by this combinatorial approach. These findings support an ongoing clinical investigation evaluating the addition of CC-122 to liso-cel in patients with R/R, aggressive NHL (NCT03310619). Citation Format: Heidi K. Jessup, Evan P. Thomas, Jim S. Qin, Yue Jiang, Oleksandr Baturevych, Neha Soni, Aye T. Chen, Ruth A. Salmon, Melissa G. Works, Michael O. Ports. Avadomide (CC-122) increases effector function and reverses exhaustion in chronically stimulated lisocabtagene maraleucel anti-CD19 CAR T drug product [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2320.

After publication of this article (Nishitani et al. 2019), it was brought to our attention that the figure 5 is incorrect, where the positions of DCE and SPS were misplaced. The correct figure 5 is as below, the original publication has been corrected.

Increasing frequency and severity of drought is driving increased use of groundwater resources in arid regions of Northern Kenya, where approximately 2.5 million people depend on groundwater for personal use, livestock, and limited irrigation. As part of a broader effort to provide more sustainable water, sanitation, and hygiene services in the region, we have collected data related to site functionality and use for approximately 120 motorized boreholes across five counties. Using a multilevel model to account for geospatial and temporal clustering, we found that borehole sites, which counties had identified as strategic assets during drought, ran on average about 1.31 h less per day compared to non-strategic borehole sites. As this finding was contrary to our hypothesis that strategic boreholes would exhibit greater use on average compared to non-strategic boreholes, we consider possible explanations for this discrepancy. We also use a coupled human and natural systems framework to explore how policies and program activities in a complex system depend on consistent and reliable feedback mechanisms. Funding was provided by the United States Agency for International Development. The views expressed in this article do not necessarily reflect the views of the United States Agency for International Development or the United States Government.

Lowering the global disease burden of preventable disease has been addressed in part by the distribution of health products and behavior change campaigns in low-income countries. Realizing a health impact requires adoption by participants, and the topic of program uptake and sustained adoption has been studied extensively, although an ecological context is largely missing from existing work. This study characterizes self-reported and observed adoption of improved cookstoves and point-of-use water filters among nearly 80,000 households in Rwanda using demographic and programmatic variables from implementer surveys and integration of geospatial and temporal data based on differentiated recipient location. The odds of stove or filter adoption were analyzed using Generalized Estimating Equation logistic regression modeling. Administrative district, rural residency, elevation, social networks, socioeconomic category, family composition, education delivery, technological factors, and use of the accompanying technology in the combined intervention were significantly associated with the odds of adoption of either the stove or filter. Population density, precipitation, anisotropic travel time to services, and timing of the health campaign largely showed no significant relationship with adoption. This research promotes the inclusion of geospatial and temporal data in designing and evaluating other public health interventions by successfully leveraging an ecological explanation of adoption decisions.

We report on the implementation of an FPGA signal processing system for a dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS). The accelerator is used for hypervelocity impact studies, including cratering and ejecta studies (ionized and neutral gases created by impact, light flashes, etc.). In addition to these research goals, the accelerator is used for the calibration of in situ dust measurement instruments. For the accelerator to be useful as a scientific tool, it must be able to detect and select accelerated dust particles before they enter the experimental apparatus. An analog detection system is capable of detecting and selecting micron-sized dust grains in-flight through a simple analog trigger. Depending on how many false triggers are allowable for the specific application, users can set the trigger level to be arbitrarily close to the noise band. To observe and select nanometer-sized grains in-flight with higher detection accuracy, a digital filtration system using cross-correlation filters has been developed to extract small signals embedded in noise. Results show the FPGA system outperforms an analog method in the total number of particle detections, the highest velocity detected, and the lowest charge detected. They also show the possibility of detecting and selecting, in real-time, nano-sized grains in laboratory dust accelerator experiments. Methods described herein can also be adapted to any real-time signal processing problem where the signals belong to a known family of shapes.

[1] We present multiple instrument observations of a storm-enhanced density (SED) during the 24–25 October 2011 intense geomagnetic storm. Formation and the subsequent evolution of the SED and the midlatitude trough are revealed by global GPS vertical total electron content maps. In addition, we present high time resolution Poker Flat Incoherent Scatter Radar (PFISR) observations of ionospheric profiles within the SED. We divided the SED observed by PFISR into two parts. Both parts are characterized by elevated ionospheric peak height (hmF2) and total electron content, compared to quiet time values. However, the two parts of the SED have different characteristics in the electron temperature (Te), the F region peak density (NmF2), and convection flows. The first part of the SED is associated with enhanced Te in the lower F region and reduced Te in the upper F region and is collocated with northward convection flows. The NmF2 was lower than quiet time values. The second part of the SED is associated with significantly increased NmF2, elevated Te at all altitudes and is located near the equatorward boundary of large northwestward flows. Based on these observations, we suggest that the mechanisms responsible for the formation of the two parts of the SED may be different. The first part is due to equatorward expansion of the convection pattern and the projection of northward convection flows in the vertical direction, which lifts the ionospheric plasma to higher altitudes and thus reduces the loss rate of plasma recombination. The second part is more complicated. Besides equatorward expansion of the convection pattern and large upward flows, evidences of other mechanisms, including horizontal advection due to fast flows, energetic particle precipitation, and enhanced thermospheric wind in the topside ionosphere, are also present. Estimates show that contribution from precipitating energetic protons is at most ~10% of the total F region density. The thermospheric wind also plays a minor role in this case.

Flattening filter‐free (FFF) beams are available on an increasing number of commercial linear accelerators. FFF beams have higher dose rates than flattened beams of equivalent energy which can lead to increased efficiency of treatment delivery, especially in conjunction with increased FFF beam energy and arc‐based delivery configurations. The purpose of this study is to quantify and assess the implications of improved treatment efficiency for several FFF delivery options on common types of linac applicable radiotherapy. Eleven characteristic cases representative of a variety of clinical treatment sites and prescription doses were selected from our patient population. Treatment plans were generated for a Varian TrueBeam linear accelerator. For each case, a reference plan was created using DMLC IMRT with 6 MV flat beams. From the same initial objectives, plans were generated using DMLC IMRT and volumetric‐modulated arc therapy (VMAT) with 6 MV FFF and 10 MV FFF beams (max. dose rates of 1400 and 2400 MU/min, respectively). The plans were delivered to a phantom; beam‐on time, total treatment delivery time, monitor units (MUs), and integral dose were recorded. For plans with low dose fractionations (1.8–2.0 & 3.85 Gy/fraction), mean beam‐on time difference between reference plan and most efficient FFF plan was 0.56 min (41.09% decrease); mean treatment delivery time difference between the reference plan and most efficient FFF plan was 1.54 min (range: 0.31–3.56 min), a relative improvement of 46.1% (range: 29.2%‐59.2%). For plans with high dose fractionations (16–20 Gy/fraction), mean beam‐on time difference was 6.79 min (74.9% decrease); mean treatment delivery time difference was 8.99 min (range: 5.40–13.05 min), a relative improvement of 71.1% (range: 53.4%‐82.4%). 10 MV FFF VMAT beams generated the most efficient plan, except in the spine SBRT case. The distribution of monitor unit counts did not vary by plan type. In cases where respiratory motion management would be applicable, 10 MV FFF DMLC IMRT reduced beam‐on time/field to less than 12 sec. FFF beams significantly reduced treatment delivery time. For radiosurgical doses, the efficiency improvement for FFF beams was clinically significant. For conventional fractionation, a large improvement in relative treatment delivery time was observed, but the absolute time savings were not likely to be of clinical value. In cases that benefit from respiratory motion management, beamon/field was reduced to a time for which most patients can comfortably maintain deep inspiratory breath hold. PACS numbers: 87.55.D‐, 87.55.de, 87.56.bd, 87.56.N‐

To better understand flow pathways and patterns in the subsurface, a stable isotope monitoring network was established at the Susquehanna-Shale Hills Critical Zone Observatory (SSHCZO). Soil water samples were collected approximately biweekly using suction-cup lysimeters installed at multiple depths along four different transects in the catchment. Groundwater and stream water were collected daily in the valley using automatic samplers, while precipitation samples were collected automatically on an event basis. The 3+ years (2008–2012) of monitoring data showed strong seasonal precipitation isotope compositions, which were imprinted in seasonal patterns of soil water at different spatial locations and depths. The groundwater isotope composition remained relatively constant throughout the year and closely matched the yearly amount-weighted precipitation average, suggesting groundwater received recharge water in each season, although recharge mechanisms differed between growing and nongrowing seasons. Soil water samples showed clear attenuation with depth, with the largest variability in the shallow soil water (≤30 cm) mirroring precipitation inputs, moderate variability in the intermediate depths (40–100 cm), and the least variability in the deep soil water (≥120 cm) where the average remained near the groundwater average. Soil water isotope composition profiles also provided clear evidence for preferential flow occurring both laterally and vertically in different seasons and at various soil depths in the catchment. Putting all together, the extensive dataset of soil water isotopic compositions obtained in this study have provided a number of insights into complex subsurface hydrologic processes that are transferable to other similar landscapes.

The amplitude and phase scintillation indices are customarily obtained by specialised GPS Ionospheric Scintillation and TEC Monitors (GISTMs) from L1 signal recorded at the rate of 50 Hz. The scintillation indices S[subscript 4] and σ[subscript Φ] are stored in real time from an array of high-rate scintillation receivers of the Canadian High Arctic Ionospheric Network (CHAIN). Ionospheric phase scintillation was observed at high latitudes during a moderate geomagnetic storm (Dst = −61 nT) that was caused by a moderate solar wind plasma stream compounded with the impact of two coronal mass ejections. The most intense phase scintillation (σ[subscript Φ] ~ 1 rad) occurred in the cusp and the polar cap where it was co-located with a strong ionospheric convection, an extended tongue of ionisation and dense polar cap patches that were observed with ionosondes and HF radars. At sub-auroral latitudes, a sub-auroral polarisation stream that was observed by mid-latitude radars was associated with weak scintillation (defined arbitrarily as σ[subscript Φ] < 0.5 rad). In the auroral zone, moderate scintillation coincided with auroral breakups observed by an all-sky imager, a riometer and a magnetometer in Yellowknife. To overcome the limited geographic coverage by GISTMs other GNSS data sampled at 1 Hz can be used to obtain scintillation proxy indices. In this study, a phase scintillation proxy index (delta phase rate, DPR) is obtained from 1-Hz data from CHAIN and other GPS receivers. The 50-Hz and 1-Hz phase scintillation indices are correlated. The percentage occurrences of σ[subscript Φ] > 0.1 rad and DPR > 2 mm s[superscript −1], both mapped as a function of magnetic latitude and magnetic local time, are very similar., National Science Foundation (U.S.) (Grant ATM-0856093)

PURPOSE: A common notion of the mechanism by which the antiepileptic drugs (AEDs) carbamazepine and phenytoin act is that they block sodium channels by binding preferentially to the inactivated state, thereby allowing normal neuronal firing while blocking ictal activity. However, these drugs have unpredictable efficacy and, in some cases, may exacerbate seizures. Previous studies have suggested that reducing sodium channel availability in the dentate gyrus (DG) paradoxically increases excitability. We used a biophysically detailed computer model of the DG to test the hypothesis that AEDs increase excitability by disproportionately reducing negative feedback mechanisms. METHODS: We built a Markov model of sodium channel gating that reproduces responses to voltage clamp experiments in the presence of carbamazepine and phenytoin. We incorporated this validated Markov model into a biophysically realistic computer model of DG neurons and networks. Simulated drug concentrations were similar to those measured in cerebral spinal fluid in medicated patients. Single neuron models were stimulated with current injections, and networks were stimulated with perforant path synaptic input. In the network model, environmental effects were studied by introducing mossy fiber sprouting. KEY FINDINGS: As expected, drugs reduced sodium channel availability, which in turn reduced action potential amplitude. This had only a small effect on action potential (AP) firing rate during brief (100 msec) current injections. Paradoxically, long current injections (2,500 msec) increased AP firing rates. This was caused by reduced calcium entry and consequently reduced activation of calcium activated potassium channels. It is important to note that the main determinant of drug effect was resting membrane potential (RMP) and not action potential firing rate. Binding of phenytoin and carbamazepine is slow and, thus drug effects are largely determined by the long term state of the RMP. This paradoxical AP firing increase was dependent on the unusually large calcium-activated potassium conductances expressed by DG granule cells. This predicts that drug efficacy in a given network will depend on the precise makeup of conductances in the network. RMP is expected to vary with the level of activity in the network. We simulated the effects of drugs on single shot stimulus responses in networks with mossy fiber sprouting and varied the RMP in all neurons as a model for network activity. For an RMP of -50 mV, representing an active network, drugs had no effect, or in some cases, increased excitability. Drugs had an increasingly larger inhibitory effect on network responses as RMP decreased. An important prediction is that drugs will be unable to block ictal activity invading an active network. SIGNIFICANCE: Our key findings are that drug effects depend on both intrinsic properties of the network and its behavioral state. This may explain the paradoxical and unpredictable effects of some AEDs on seizure control in some patients.

[1] We examine the relationship of convection electric fields to the formation of a polar cap tongue of ionization (TOI) from midlatitude plumes of storm enhanced density (SED). Observations from the geomagnetic storm on 26–27 September 2011 are presented for two distinct SED events. During an hour-long period of geomagnetic activity driven by a coronal mass ejection, a channel of high-density F region plasma was transported from the dayside subauroral ionosphere and into the polar cap by enhanced convection electric fields extending to middle latitudes. This TOI feature was associated with enhanced HF backscatter, indicating that it was the seat of active formation of small-scale irregularities. After the solar wind interplanetary magnetic field conditions quieted and the dayside convection electric fields retreated to higher latitudes, an SED plume was observed extending to, but not entering, the dayside cusp region. This prominent feature in the distribution of total electron content (TEC) persisted for several hours and elongated in magnetic local time with the rotation of the Earth. No ionospheric scatter from SuperDARN radars was observed within this SED region. The source mechanism (enhanced electric fields) previously drawing the plasma from midlatitudes and into the polar cap as a TOI was no longer active, resulting in a fossil feature. We thus demonstrate the controlling role exercised by the convection electric field in generating a TOI from midlatitude SED.

The geomagnetic storm of 17–18 March 2015 was caused by the impacts of a coronal mass ejection and a high-speed plasma stream from a coronal hole. The high-latitude ionosphere dynamics is studied using arrays of ground-based instruments including GPS receivers, HF radars, ionosondes, riometers, and magnetometers. The phase scintillation index is computed for signals sampled at a rate of up to 100 Hz by specialized GPS scintillation receivers supplemented by the phase scintillation proxy index obtained from geodetic-quality GPS data sampled at 1 Hz. In the context of solar wind coupling to the magnetosphere-ionosphere system, it is shown that GPS phase scintillation is primarily enhanced in the cusp, the tongue of ionization that is broken into patches drawn into the polar cap from the dayside storm-enhanced plasma density, and in the auroral oval. In this paper we examine the relation between the scintillation and auroral electrojet currents observed by arrays of ground-based magnetometers as well as energetic particle precipitation observed by the DMSP satellites. Equivalent ionospheric currents are obtained from ground magnetometer data using the spherical elementary currents systems technique that has been applied over the ground magnetometer networks in North America and North Europe. The GPS phase scintillation is mapped to the poleward side of strong westward electrojet and to the edge of the eastward electrojet region. Also, the scintillation was generally collocated with fluxes of energetic electron precipitation observed by DMSP satellites with the exception of a period of pulsating aurora when only very weak currents were observed.