Isotropic-medium three-dimensional cloaks for acoustic and electromagnetic waves

We propose a generalization of the two-dimensional eikonal-limit cloak derived from a conformal transformation to three dimensions. The proposed cloak is a spherical shell composed of only isotropic media; it operates in the transmission mode and requires no mirror or ground plane. Unlike the well-known omnidirectional spherical cloaks, it may reduce visibility of an arbitrary object only for a very limited range of observation angles. In the short-wavelength limit, this cloaking structure restores not only the trajectories of incident rays, but also their phase, which is a necessary ingredient to complete invisibility. Both scalar-wave (acoustic) and transverse vector-wave (electromagnetic) versions are presented.Comment: 17 pages, 12 figure

Best Practices for Environmental Field Days: Structuring Your Event for Fun and Learning

Six Best Practices for environmental field days will help you deliver a clear message at almost any non-formal educational event involving schoolchildren, natural resource professionals, and volunteers. Based on research and experience, the guidelines form a practical foundation for field-day planning focused on understanding participants\u27 needs, developing concise goals, and communicating goals effectively. The practices will ensure better learning for the hundreds of thousands of students who attend such events around the country every year

Marine Robot Sample Retrieving System

The exploration of our underwater ecosystems is critical. The aquatic ecosystem has a significant effect on human life, yet our understanding of the oceanic environment is severely lacking. Santa Clara University’s Robotic Systems Lab contributes to subsea exploration through its investment in remotely operated vehicle (ROV) technology. This project was done with the guidance of not only professors in the Robotics Systems Lab, but also stakeholders from the US Geological Survey scientists and researchers from the Monterey Bay Aquarium Research Institute (MBARI). Our team goal was to further advance SCU’s efforts by creating a sediment sample collection system consisting of a manipulator arm and sample storage container compatible with an existing SCU ROV. Our project has the potential to give researchers better access to submerged ecosystems and assists their efforts to understand and protect subsea environments in the future. We designed, built, and tested a prototype of a multiple degree-of-freedom arm and storage system for the existing Nautilus ROV, for safely manipulating and storing submerged sedimentary artifacts at 300 feet deep with a maximum dive time of 45 minutes. At the end of this project, we were able to see robust three degree of freedom movement of the arm within its anticipated workspace. We achieved a basic level of motion control of the arm which was successfully tested and evaluated within a testing tank. However, there is still need for additional testing and increased functionality of the mechanical and controls systems. The storage system for samples design needs a thrust bearing to better rotate and there is still much work to make the controls of the arm user friendly such as end effector control for depositing a sample into the storage system instead of doing all the movements manually

Marine Robot Sample Retrieving System

The exploration of our underwater ecosystems is critical. The aquatic ecosystem has a significant effect on human life, yet our understanding of the oceanic environment is severely lacking. Santa Clara University’s Robotic Systems Lab contributes to subsea exploration through its investment in remotely operated vehicle (ROV) technology. This project was done with the guidance of not only professors in the Robotics Systems Lab, but also stakeholders from the US Geological Survey scientists and researchers from the Monterey Bay Aquarium Research Institute (MBARI). Our team goal was to further advance SCU’s efforts by creating a sediment sample collection system consisting of a manipulator arm and sample storage container compatible with an existing SCU ROV. Our project has the potential to give researchers better access to submerged ecosystems and assists their efforts to understand and protect subsea environments in the future. We designed, built, and tested a prototype of a multiple degree-offreedom arm and storage system for the existing Nautilus ROV, for safely manipulating and storing submerged sedimentary artifacts at 300 feet deep with a maximum dive time of 45 minutes. At the end of this project, we were able to see robust three degree of freedom movement of the arm within its anticipated workspace. We achieved a basic level of motion control of the arm which was successfully tested and evaluated within a testing tank. However, there is still need for additional testing and increased functionality of the mechanical and controls systems. The storage system for samples design needs a thrust bearing to better rotate and there is still much work to make the controls of the arm user friendly such as end effector control for depositing a sample into the storage system instead of doing all the movements manually

Ambrisentan response in connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH) - A subgroup analysis of the ARIES-E clinical trial.

OBJECTIVE: Pulmonary arterial hypertension (PAH) is a condition which may lead to right ventricular failure and early mortality and is an important complication in patients with connective tissue disease (CTD). Previously, the endothelin A selective receptor antagonist, ambrisentan, demonstrated efficacy and safety in treating patients with PAH due to WHO Group I etiologies. These analyses describe the 3-year efficacy and safety of ambrisentan in patients specifically with CTD associated PAH (CTD-PAH). METHODS: Patients with CTD-PAH participating in the ARIES-1 and -2 clinical trials and their long-term extension were evaluated. Efficacy evaluations including 6-min walk distance (6MWD), clinical worsening, and survival were collected at routine study visits. Additional analyses of 6MWD categorical (30 m) breakpoints were conducted to determine any relationship between 6MWD and a prognostic threshold for survival. RESULTS: 124 patients with CTD-PAH were evaluated. 62.6%, 57.3%, and 58.2% of CTD-PAH patients treated with ambrisentan exhibited increases in 6MWD at 1-, 2-, and 3- years respectively. At 3 years, 64% of patients were free from clinical worsening and 76% of patients were still alive (Kaplan-Meier estimates). Identified factors holding prognostic relevance for survival include: baseline functional class, CTD-PAH subgroup, patient sex, improvement in 6MWD ≥30 m over the first 12 weeks of treatment, the most recent 6MWD, and a 6MWD absolute threshold of 222 m. CONCLUSION: These first analyses of the 3-year treatment of CTD-PAH patients with ambrisentan revealed fewer clinical worsening events and improved survival compared to historical controls. Key exercise parameters were also identified which appear important in guiding treatment

A new platform for validating real-time, large-scale WAMPAC systems

A platform for emulating 64 Phasor Measurement Units (PMUs), with data from a real-time simulation, has been developed. An RTDS simulator has been used to provide IEC 61850-9-2 Sampled Value data, representing three-phase voltage and current measurements from up to 64 power system locations, and the platform efficiently processes the data using cost-effective ARM-based devices, which output synchrophasor data according to the IEEE C37.118.2 protocol. The platform provides flexibility to configure the PMU class and reporting rate at run-time. The paper analyses the measured report latency of the PMUs under a variety of configurations. This development provides a cost-effective system for demonstrating wide-area visualisation, control, and protection schemes

Impact of interhospital transfer on patients undergoing endovascular thrombectomy for acute ischaemic stroke in an Australian setting

Objective To assess the impact of interhospital transfer on the interplay between functional outcome, mortality, reperfusion rates and workflow time metrics in patients undergoing endovascular thrombectomy (EVT) for acute ischaemic stroke due to large vessel occlusion (LVO) in the anterior cerebral circulation. Design, setting and participants This is an analysis of a prospective database of consecutive patients undergoing EVT for LVO presenting between January 2017 and December 2018 at a single Australian comprehensive stroke centre (CSC). Patients presented directly or were transferred to the CSC from 21 sites across New South Wales and the Australian Capital Territory. Main outcome measures The main outcome measures were rate of good 90-day functional outcome (modified Rankin Scale 0–2), successful reperfusion (Thrombolysis in Cerebral Infarction scale grade 2b or 3), symptomatic intracerebral haemorrhage (sICH) and 90-day mortality. Key workflow time metric milestones were examined. Results 154 of 213 (72%) patients were interhospital transfers. There was no significant difference in baseline characteristics including age, National Institutes of Health Stroke Scale score, intravenous thrombolysis administration or procedure time between transferred and direct presenters (all p>0.05). Transferred patients had worse 90-day functional outcome (39.6% vs 61.0%, OR 0.42, 95% CI 0.23 to 0.78), higher mortality (25.3% vs 6.8%, OR 4.66, CI 1.59 to 13.70) and longer stroke onset to treatment (groin puncture) time (298 min vs 205 min, p<0.01). Successful reperfusion rates and sICH were similar between the cohorts (96.8% vs 98.3%, and 7.8% vs 3.4%). Conclusion Interhospital transfer is associated with longer stroke onset to treatment, worse 90-day functional outcome and higher mortality compared with patients presenting directly to the CSC

Hubble Space Telescope Observations of Oxygen-rich Supernova Remnants in the Magellanic Clouds. III. WFPC2 Imaging of the Young, Crab-like Supernova Remnant SNRO540-69.3

Hubble Space Telescope images with the Wide Field Planetary Camera 2 of the young, oxygen-rich, Crab-like supernova remnant SNR0540-69.3 in the Large Magellanic Cloud (LMC) reveal details of the emission distribution and the relationship between the expanding ejecta and synchrotron nebula. The emission distributions appear very similar to those seen in the Crab nebula, with the ejecta located in a thin envelope surrounding the synchrotron nebula. The [O III] emission is more extended than other tracers, forming a faint "skin" around the denser filaments and synchrotron nebula, as also observed in the Crab. The [O III] exhibits somewhat different kinematic structure in long-slit spectra, including a more extended high-velocity emission halo not seen in images. Yet even the fastest expansion speeds in SNR 0540 s halo are slow when compared to most other young supernova remnants, though the Crab nebula has similar slow expansion speeds. We show a striking correspondence between the morphology of the synchrotron nebula observed in an optical continuum filter with that recently resolved in Chandra X-ray images. We argue that the multi-component kinematics and filamentary morphology of the optical emission-line features likely result from magnetic Rayleigh-Taylor instabilities that form as the synchrotron nebula expands and sweeps up ejecta, as seen in the Crab nebula. Our images and spectra help to refine our understanding of SNR 0540 in several more detailed respects: they confirm the identification of H(alpha)+[N II] in the red spectrum, they show that the systemic velocity of SNR 0540 is not significantly different from that of the LMC, and they hint at a lower Ne abundance than the Crab (potentially indicating a more massive progenitor star)