Marimo actuated rover systems

Background The potential to directly harness photosynthesis to make actuators, biosensors and bioprocessors has been previously demonstrated in the literature. Herein, this capability has been expanded to more advanced systems — Marimo Actuated Rover Systems (MARS) — which are capable of autonomous, solar powered, movement. Results We demonstrate this ability is both a practical and viable alternative to conventional mobile platforms for exploration and dynamic environmental monitoring. Prototypes have been successfully tested to measure their speed of travel and ability to automatically bypass obstacles. Further, MARS is electromagnetically silent, thus avoiding the background noise generated by conventional electro/mechanical platforms which reduces instrument sensitivity. The cost of MARS is significantly lower than platforms based on conventional technology. Conclusions An autonomous, low-cost, lightweight, compact size, photosynthetically powered rover is reported. The potential for further system enhancements are identified and under development.

Detection of Substructures in Young Transition Disk WL 17

WL 17 is a young transition disk in the Ophiuchus L1688 molecular cloud complex. Even though WL 17 is among the brightest disks in L1688 and massive enough to expect dust self-scattering, it was undetected in polarization down to Atacama Large Millimeter/submillimeter Array’s (ALMA’s) instrument sensitivity limit. Such low polarization fractions could indicate unresolved polarization within the beam or optically thin dust emission. We test the latter case by combining the high-sensitivity 233 GHz Stokes I data from the polarization observations with previous ALMA data at 345 and 100 GHz. We use simple geometric shapes to fit the observed disk visibilities in each band. Using our simple models and assumed dust temperature profiles, we estimate the optical depth in all three bands. The optical depth at 233 GHz peaks at τ 233 ∼ 0.3, which suggests the dust emission may not be optically thick enough for dust self-scattering to be efficient. We also find the higher-sensitivity 233 GHz data show substructure in the disk for the first time. The substructure appears as brighter lobes along the major axis, on either side of the star. We attempt to fit the lobes with a simple geometric model, but they are unresolved in the 233 GHz data. We propose that the disk may be flared at 1 mm such that there is a higher column of dust along the major axis than the minor axis when viewed at an inclination. These observations highlight the strength of high-sensitivity continuum data from dust polarization observations to study disk structures.

Repeatability and sensitivity characterization of the far-field high-energy diffraction microscopy instrument at the Advanced Photon Source

In the last two decades, far-field high-energy diffraction microscopy (FF-HEDM) and similar non-destructive techniques have been actively developed at synchrotron light sources around the world. As these techniques (and associated analysis tools) are becoming more available for the general users of these light sources, it is important and timely to characterize their performance and capabilities. In this work, the FF-HEDM instrument implemented at the 1-ID-E endstation of the Advanced Photon Source (APS) is summarized. The set of measurements conducted to characterize the instrument's repeatability and sensitivity to changes in grain orientation and position are also described. When an appropriate grain matching method is used, the FF-HEDM instrument's repeatability is approximately 5 µm in translation, 0.02° in rotation, and 2 × 10−4 in strain; the instrument sensitivity is approximately 5 µm in translation and 0.05° in rotation.

Polarization of hot Jupiter systems: a likely detection of stellar activity and a possible detection of planetary polarization

ABSTRACT We present high-precision linear polarization observations of four bright hot Jupiter systems (τ Boo, HD 179949, HD 189733, and 51 Peg) and use the data to search for polarized reflected light from the planets. The data for 51 Peg are consistent with a reflected light polarization signal at about the level expected with 2.8σ significance and a false alarm probability of 1.9 per cent. More data will be needed to confirm a detection of reflected light in this system. HD 189733 shows highly variable polarization that appears to be most likely the result of magnetic activity of the host star. This masks any polarization due to reflected light, but a polarization signal at the expected level of ∼20 ppm cannot be ruled out. τ Boo and HD 179949 show no evidence for polarization due to reflected light. The results are consistent with the idea that many hot Jupiters have low geometric albedos. Conclusive detection of polarized reflected light from hot Jupiters is likely to require further improvements in instrument sensitivity.

Identification of infrasonic and seismic components of tremors in single-station records: application to the 2013 and 2018 events at Ioto Island, Japan

Infrasonic stations are sparse at many volcanoes, especially those on remote islands and those with less frequent eruptions. When only a single infrasound station is available, the seismic–infrasonic cross-correlation method has been used to extract infrasound from wind noise. However, it does not work with intense seismicity and sometimes mistakes ground-to-atmosphere signals as infrasound. This paper proposes a complementary method to identify the seismic component and the infrasonic component using a single microphone and a seismometer. We applied the method to estimate the surface activity on Ioto Island. We focused on volcanic tremors during the phreatic eruption on April 11, 2013, and during an unconfirmed event on September 12, 2018. We used the spectral amplitude ratios of the vertical ground motion to the pressure oscillation and compared those for the tremors with those for known signals generated by volcano-tectonic earthquakes and airplanes flying over the station. We were able to identify the infrasound component in the part of the seismic tremor with the 2013 eruption. On the other hand, the tremor with the unconfirmed 2018 event was accompanied by no apparent infrasound. We interpreted the results that the infrasound with the 2013 event was excited by the vent opening or the ejection of ballistic rocks, and the 2018 event was not an explosive eruption either on the ground or in the shallow water. If there was any gas (and ash) emission, it might have occurred gently undersea. As the method uses the relative values of on-site records instead of the absolute values, it is available even if the instrument sensitivity and the station site effects are poorly calibrated.

Mass Sensitivity or Gravimetric Satellites

<p class="p1">A point mass on the surface of the Earth gives the highest frequency content for orbiting gravimetry, with<span class="Apple-converted-space">  </span>the maximum frequency for gradiometers or satellite-to-satellite tracking determined by orbital altitude.  Frequency-domain expressions are found for<span class="Apple-converted-space">  </span>measurements of a point-like source on the surface of the Earth.<span class="Apple-converted-space">  </span>The response of orbiting gradiometers such as GOCE and satellite-to-satellite tracking missions such as GRACE-FO are compared. The optimal signal-to-noise ratio as a function<span class="Apple-converted-space">  </span>of noise in the measurement apparatus is computed, and from that the minimum detectable mass is inferred. The point mass magnitude that gives signal-to-noise ratio = 3 is for GOCE<span class="Apple-converted-space">  </span>M_3=200 Gton and<span class="Apple-converted-space">  </span>for the laser ranging interferometer measurement on GRACE-FO<span class="Apple-converted-space">  </span>M_3= 0.5 Gton. For the laser ranging interferometer measurement, the optimal filter for detecting point-like masses has a passband of 1 to 20 mHz,<span class="Apple-converted-space">  </span>differing from the 0.3 to 20 mHz admittance filter of Ghobadi-Far et al. (2018), which is not specialized for detecting point-like masses. M_3 for<span class="Apple-converted-space">  </span>future GRACE-like missions with different orbital parameters and improved instrument sensitivity is explored, and the optimum spacecraft separation is found.</p>

Assessing COVID-19 related anxiety among nurses in Malawi

Introduction: Psychological wellbeing of nurses is crucial for them to effectively discharge their duties. However, COVID-19 related anxiety can interfere with nurses’ performance in their duties and reduce their self-efficacy levels.Aim: This study aimed at assessing COVID-19 related anxiety among nurses in Malawi.Method: This was a cross-sectional study that collected data from 102 nurses online. Data were analysed using descriptive statistics and receiver operating curve analysis.Results: This study found that 25.5% (n=26) of respondents had COVID-19 related anxiety and 48% (n=49) functional impairment. There were significant differences in the numbers of respondents who had functional impairment in relation to workplace (χ2=8.7, p= 0.03) with many of those working in hospitals (58.6%, n=34) having highest levels (Mean =20.6±10.4). The Coronavirus Anxiety Scale proved to be an effective instrument (Sensitivity=73.1%; Specificity=60.5%; AUC=0.73) for assessing COVID-19 related anxiety among nurses.Discussion: Prevalence of COVID-19 related anxiety is high among nurses and many of them experience functional impairment. The CAS should be used in clinical practice for detecting COVID-19 related anxiety among nurses.Implications for practiceNurses should be screened of COVID-19 related anxiety using valid instrument. Psychosocial interventions should be part of preparedness to reduce COVID-19 impact on nurses.

FACS-Based Proteomics Enables Profiling of Proteins in Rare Cell Populations

Understanding disease pathology often does not require an overall proteomic analysis of clinical samples but rather the analysis of different, often rare, subpopulations of cells in a heterogeneous mixture of cell types. For the isolation of pre-specified cellular subtypes, fluorescence activated cell sorting (FACS) is commonly used for its ability to isolate the required cell populations with high purity, even of scarce cell types. The proteomic analysis of a limited number of FACS-sorted cells, however, is very challenging as both sample preparation inefficiencies and limits in terms of instrument sensitivity are present. In this study, we used CD14+CD15+ immune cells sorted out of peripheral blood mononuclear cells isolated from whole blood to improve and evaluate FACS-based proteomics. To optimize both the protein extraction protocol and the mass spectrometry (MS) data acquisition method, PBMCs as well as commercialized HeLa digest were used. To reflect the limited number of sorted cells in some clinical samples, different numbers of sorted cells (1000, 5000, 10,000, or 50,000) were used. This allowed comparing protein profiles across samples with limited protein material and provided further insights in the benefits and limitations of using a very limited numbers of cells.

Identification of infrasonic and seismic components of tremors in single-station records: application to the 2013 and 2018 events at Ioto Island, Japan

Infrasonic stations are sparse at many volcanoes, especially those on remote islands and those with less frequent eruptions. When only a single infrasound station is available, the seismic-infrasonic cross-correlation method has been used to extract infrasound from wind noise. However, it does not work with intense seismicity and sometimes mistakes ground-to-atmosphere signals as infrasound. This paper proposes a complementary method to identify the seismic component and the infrasonic component using a single microphone and a seismometer. We applied the method to estimate the surface activity on Ioto Island. We focused on volcanic tremors during the phreatic eruption on April 11, 2013, and during an unconfirmed event on September 12, 2018. We used the spectral amplitude ratios of the vertical ground motion to the pressure oscillation and compared those for the tremors with those for known signals generated by volcano-tectonic earthquakes and airplanes flying over the station. We were able to identify the infrasound component in the part of the seismic tremor with the 2013 eruption. On the other hand, the tremor with the unconfirmed 2018 event was accompanied by no apparent infrasound. We interpreted the results that the infrasound with the 2013 event was excited by the vent opening or the ejection of ballistic rocks, and the 2018 event was not an explosive eruption either on the ground or in the shallow water. If there was any gas (and ash) emission, it might have occurred gently undersea. As the method uses the relative values of on-site records instead of the absolute values, it is available even if the instrument sensitivity and the station site effects are poorly calibrated.

Spacecraft and interplanetary contributions to the magnetic environment on-board LISA Pathfinder

ABSTRACT LISA Pathfinder (LPF) has been a space-based mission designed to test new technologies that will be required for a gravitational wave observatory in space. Magnetically driven forces play a key role in the instrument sensitivity in the low-frequency regime (mHz and below), the measurement band of interest for a space-based observatory. The magnetic field can couple to the magnetic susceptibility and remanent magnetic moment from the test masses and disturb them from their geodesic movement. LPF carried on-board a dedicated magnetic measurement subsystem with noise levels of 10 $\rm nT \ Hz^{-1/2}$ from 1 Hz down to 1 mHz. In this paper we report on the magnetic measurements throughout LPF operations. We characterize the magnetic environment within the spacecraft, study the time evolution of the magnetic field and its stability down to 20 μHz, where we measure values around 200 $\rm nT \ Hz^{-1/2}$, and identify two different frequency regimes, one related to the interplanetary magnetic field and the other to the magnetic field originating inside the spacecraft. Finally, we characterize the non-stationary component of the fluctuations of the magnetic field below the mHz and relate them to the dynamics of the solar wind.