Position Control of Tendon-Driven Fingers

Conventionally, tendon-driven manipulators implement some force control scheme based on tension feedback. This feedback allows the system to ensure that the tendons are maintained taut with proper levels of tensioning at all times. Occasionally, whether it is due to the lack of tension feedback or the inability to implement sufficiently high stiffnesses, a position control scheme is needed. This work compares three position controllers for tendon-driven manipulators. A new controller is introduced that achieves the best overall performance with regards to speed, accuracy, and transient behavior. To compensate for the lack of tension feedback, the controller nominally maintains the internal tension on the tendons by implementing a two-tier architecture with a range-space constraint. These control laws are validated experimentally on the Robonaut-2 humanoid hand.

Secondary non-invasive prenatal screening for fetal trisomy: an effectiveness study in a public health setting.

OBJECTIVE: To evaluate the effectiveness of secondary screening using non-invasive prenatal testing (NIPT) in a routine NHS setting including test performance, turn-around times (TATs) and no-call (failure to obtain result) rates. To examine the influence of maternal and fetal characteristics on test performance. DESIGN: Retrospective cohort. SETTING: London teaching hospital. SAMPLE: A total of 8651 pregnancies undergoing screening for fetal trisomy using NIPT provided by an NHS cell-free DNA screening laboratory - the SAFE laboratory. METHODS: Screening test evaluation and TATs. Univariate and multivariate logistic regression analysis to identify significant predictors of no-call results and reported by low fetal fraction (40%) and processing failure. MAIN OUTCOME MEASURES: Test performance, TATs and no-call rates, factors affecting no-call results. RESULTS: Average TAT was 4.0 days (95% CI 4.0-4.2 days). Test sensitivities for trisomies 21 and 13/18 were 98.9% (95% CI 95.9-99.9%) and 90.4% (95% CI 80.0-96.8%), respectively. The overall no-call rate was 32/8651 (0.37%, 95% CI 0.26-0.52%). The overall risk of a no-call result was influenced by gestational age, dichorionic twin pregnancy, history of malignancy and pregnancies affected by trisomy 13/18, but not by maternal weight or use of low-molecular-weight heparin. CONCLUSIONS: High-throughput NIPT can be effectively embedded into a public health NHS setting. TATs of 4 days and no-calls of <0.5% were well within clinically desirable tolerances. Gestational age, maternal weight, assisted reproductive techniques, use of low-molecular-weight heparin and past history of malignancy did not have major impacts on test no-call rates and should not constitute reasons for withholding the option of NIPT from women. TWEETABLE ABSTRACT: Turn-around times of 4 days, no-call (test failure) rates of 0.37% and highly accurate NIPT can be successfully embedded in the NHS

Comparison of Mehlich-3 and DTPA Soil Tests for Analysis of Micronutrients in Kansas Soils

Mehlich-3 (M3) was designed as a multi-nutrient soil test procedure and has become common at soil testing labs across the U.S. In Kansas, Mehlich-3 is predominately used as a soil test for phosphorus (P) and potassium (K), but recent studies have also investigated the use of M3 for the extraction of base cations and cation exchange capacity estimation. However, data relating M3 to traditional methods for soil micronutrient extraction remain scarce. The objective of this study was to investigate the relationship between M3 and diethylenetriamine pentaacetate (DTPA) extractable copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) across a wide range of Kansas soils. Strong positive correlations were observed between M3 and DTPA for each metal (Fe, r = .91; Zn, r = .98; Cu, r = .92). Correlations between M3 and DTPA were positive but weak for Mn (r = 0.17). Regression analyses suggest these relationships were not one-to-one and were dependent on soil pH. Results from this study show that conversion of M3 to a “DTPA equivalent” is possible but should take soil pH into consideration, especially for Fe and Mn

Toxaphene and Other Organochlorines in Arctic Ocean Fauna: Evidence for Atmospheric Delivery

Residues of the insecticide toxaphene (polychlorinated camphenes, PCCs) and other organochlorines (OCs) were determined in air, snow, seawater, zooplankton, and benthic amphipods collected from an ice island in the Canadian Arctic. The simultaneous determination of OCs in the atmospheric, hydrologic, and biologic compartments provided evidence of an atmospheric link to polar food chains. PCCs were identified and quantified using capillary gas chromatography - negative ion mass spectrometry. The order of OCs abundance in arctic air was: hexachlorocyclohexanes (HCHs) &gt; hexachlorobenzene &gt; PCCs &gt; polychlorinated biphenyls (PCBs) &gt; chlordanes &gt; DDTs. In seawater, PCCs were exceeded only by the HCHs. Concentrations of PCBs and PCCs in two samples of benthic amphipods were the highest of the OCs detected.Key words: Arctic, Canada, pollution, organochlorines, air, water, biotaMots cl&eacute;s: Arctique, Canada, pollution, organochlor&eacute;s, air, eau, biot

Surveillance imaging of grade 1 astrocytomas in children: can duration and frequency of follow-up imaging and the use of contrast agents be reduced?

Purpose: The optimum strategy for the surveillance of low-grade gliomas in children has not been established, and there is concern about the use of gadolinium-based contrast agents (GBCAs), particularly in children, due to their deposition in the brain. The number of surveillance scans and the use of GBCAs in surveillance of low-risk tumours should ideally be limited. We aimed to investigate the consistency and utility of our surveillance imaging and also determine to what extent the use of GBCAs contributed to decisions to escalate treatment in children with grade 1 astrocytomas. / Methods: This was a retrospective single-centre study at a tertiary paediatric hospital. All children with a new diagnosis of a non-syndromic World Health Organization (WHO) grade 1 astrocytoma between 2007 and 2013 were included, with surveillance imaging up to December 2018 included in analysis. The intervals of surveillance imaging were recorded, and imaging and electronic health records were examined for decisions related to treatment escalation. / Results: Eighty-eight patients had 690 surveillance scans in the study period. Thirty-one patients had recurrence or progression leading to treatment escalation, 30 of whom were identified on surveillance imaging. The use of GBCAs did not appear to contribute to multidisciplinary team (MDT) decisions in the majority of cases. / Conclusion: Surveillance imaging could be reduced in number and duration for completely resected cerebellar tumours. MDT decisions were rarely made on the basis of post-contrast imaging, and GBCA administration could therefore potentially be restricted in the setting of surveillance of grade 1 astrocytomas in children

PILOT: a balloon-borne experiment to measure the polarized FIR emission of dust grains in the interstellar medium

Future cosmology space missions will concentrate on measuring the polarization of the Cosmic Microwave Background, which potentially carries invaluable information about the earliest phases of the evolution of our universe. Such ambitious projects will ultimately be limited by the sensitivity of the instrument and by the accuracy at which polarized foreground emission from our own Galaxy can be subtracted out. We present the PILOT balloon project which will aim at characterizing one of these foreground sources, the polarization of the dust continuum emission in the diffuse interstellar medium. The PILOT experiment will also constitute a test-bed for using multiplexed bolometer arrays for polarization measurements. We present the results of ground tests obtained just before the first flight of the instrument.Comment: 17 pages, 13 figures. Presented at SPIE, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VII. To be published in Proc. SPIE volume 915

Comparison of Mehlich-3 and Ammonium Acetate Extractable Calcium and Magnesium in Kansas Soils

The use of the Mehlich-3 (M3) soil test procedure to assess the plant availability of numerous macro and micronutrients has become common at soil testing labs across the US. Mehlich-3 is used for soil tests for phosphorus (P) and potassium (K) in Kansas; however, data for other base cations for existing methods are scarce for Kansas soils. The objective of this study was to investigate the relationship between M3 and ammonium acetate (AA) extractable calcium (Ca) and magnesium (Mg). Regression analyses indicate a near 1:1 linear relationship between M3-Mg and AA-Mg across a wide range of soil pH and soil organic matter (SOM) contents. The relationship between M3-Ca and AA-Ca was relatively constant for acidic to neutral pH soils. However, M3 extracted substantially more Ca in higher pH soils. Regression analysis indicates that M3-Ca and AA-Ca diverge exponentially at a soil pH of 7.3 and higher. Given the current interpretation of AA-Ca as a measure of exchangeable Ca, these results suggest that M3 may extract Ca from non-exchangeable soil-Ca pools in soils with above neutral pH levels. Based on these results, M3 should not be used to assess the plant availability of soil-Ca or estimate cation exchange capacity (CEC) in soils with a pH above 7.3, as the values are likely to be overestimated

The Electron Energy Distribution in the Hotspots of Cygnus A: Filling the Gap with the Spitzer Space Telescope

Here we present Spitzer Space Telescope imaging of Cyg A with the Infrared Array Camera, resulting in the detection of the high-energy tails or cut-offs in the synchrotron spectra for all four hotspots of this archetype radio galaxy. When combined with the other data collected from the literature, our observations allow for detailed modeling of the broad-band emission for the brightest spots A and D. We confirm that the X-ray flux detected previously from these features is consistent with the synchrotron self-Compton radiation for the magnetic field intensity 170 muG in spot A, and 270 muG in spot D. We also find that the energy density of the emitting electrons is most likely larger by a factor of a few than the energy density of the hotspots' magnetic field. We construct energy spectra of the radiating ultrarelativistic electrons. We find that for both hotspots A and D these spectra are consistent with a broken power-law extending from at least 100 MeV up to 100 GeV, and that the spectral break corresponds almost exactly to the proton rest energy of 1 GeV. We argue that the shape of the electron continuum reflects two different regimes of the electron acceleration process at mildly relativistic shocks, rather than resulting from radiative cooling and/or absorption effects. In this picture the protons' inertia defines the critical energy for the hotspot electrons above which Fermi-type acceleration processes may play a major role, but below which the operating acceleration mechanism has to be of a different type. At energies >100 GeV, the electron spectra cut-off/steepen again, most likely as a result of spectral aging due to radiative loss effects. We discuss several implications of the presented analysis for the physics of extragalactic jets.Comment: 29 pages, 8 figures and 2 tables included. Accepted for publication in Ap