A Large-Diameter Hollow-Shaft Cryogenic Motor Based on a Superconducting Magnetic Bearing for Millimeter-Wave Polarimetry

In this paper we present the design and measured performance of a novel cryogenic motor based on a superconducting magnetic bearing (SMB). The motor is tailored for use in millimeter-wave half-wave plate (HWP) polarimeters, where a HWP is rapidly rotated in front of a polarization analyzer or polarization-sensitive detector. This polarimetry technique is commonly used in cosmic microwave background (CMB) polarization studies. The SMB we use is composed of fourteen yttrium barium copper oxide (YBCO) disks and a contiguous neodymium iron boron (NdFeB) ring magnet. The motor is a hollow-shaft motor because the HWP is ultimately installed in the rotor. The motor presented here has a 100 mm diameter rotor aperture. However, the design can be scaled up to rotor aperture diameters of approximately 500 mm. Our motor system is composed of four primary subsystems: (i) the rotor assembly, which includes the NdFeB ring magnet, (ii) the stator assembly, which includes the YBCO disks, (iii) an incremental encoder, and (iv) the drive electronics. While the YBCO is cooling through its superconducting transition, the rotor is held above the stator by a novel hold and release mechanism (HRM). The encoder subsystem consists of a custom-built encoder disk read out by two fiber optic readout sensors. For the demonstration described in this paper, we ran the motor at 50 K and tested rotation frequencies up to approximately 10 Hz. The feedback system was able to stabilize the the rotation speed to approximately 0.4%, and the measured rotor orientation angle uncertainty is less than 0.15 deg. Lower temperature operation will require additional development activities, which we will discuss

Can hyperbolic phase of Brans-Dicke field account for Dark Matter?

We show that the introduction of a hyperbolic phase for Brans-Dicke (BD) field results in a flat vacuum cosmological solution of Hubble parameter H and fractional rate of change of BD scalar field, F which asymptotically approach constant values. At late stages, hyperbolic phase of BD field behaves like dark matter

The impact of vatinoxan on medetomidine-ketamine-midazolam immobilization in Patagonian maras (Dolichotis patagonum)

Objective To compare cardiovascular and ventilatory effects, immobilization quality and effects on tissue perfusion of a medetomidine-ketamine-midazolam combination with or without vatinoxan (MK-467), a peripherally acting alpha(2)-adrenoceptor antagonist. Study design Randomized, blinded, crossover study. Animals A group of nine healthy Patagonian maras (Dolichotis patagonum). Methods Maras were immobilized twice with: 1) medetomidine hydrochloride (0.1 mg kg(-1)) + ketamine (5 mg kg(-1)) + midazolam (0.1 mg kg(-1)) (MKM) + saline or 2) MKM + vatinoxan hydrochloride (0.8 mg kg(-1)), administered intramuscularly. Drugs were mixed in the same syringe. At 20, 30 and 40 minutes after injection, invasive blood pressure, heart rate, respiration rate, end-tidal CO2, haemoglobin oxygen saturation, and muscle oxygenation were measured, arteriovenous oxygen content difference was calculated. Muscle tone, jaw tone, spontaneous blinking and palpebral reflex were evaluated. Times to initial effect, recumbency, initial arousal and control of the head were recorded. Paired t test, Wilcoxon matched-pairs signed rank test and analysis of variance were used to compare protocols; (p 120 mmHg), whereas with 372 vatinoxan, four animals were hypotensive (MAP <60 mmHg). Muscle and jaw tone were significantly more frequently present with MKM (both p = 0.039). Other measurements did not significantly differ between protocols. Conclusions and clinical relevance In Patagonian maras, vatinoxan attenuated the increase in blood pressure induced by medetomidine. Muscle and jaw tone were more frequently present with MKM, indicating that quality of immobilization with vatinoxan was more profound.Peer reviewe

Impact of a training program on the surveillance of Clostridioides difficile infection

A high degree of vigilance and appropriate diagnostic methods are required to detect Clostridioides difficile infection (CDI). We studied the effectiveness of a multimodal training program for improving CDI surveillance and prevention. Between 2011 and 2016, this program was made available to healthcare staff of acute care hospitals in Catalonia. The program included an online course, two face-to-face workshops and dissemination of recommendations on prevention and diagnosis. Adherence to the recommendations was evaluated through surveys administered to the infection control teams at the 38 participating hospitals. The incidence of CDI increased from 2.20 cases/10 000 patient-days in 2011 to 3.41 in 2016 (P < 0.001). The number of hospitals that applied an optimal diagnostic algorithm rose from 32.0% to 71.1% (P = 0.002). Hospitals that applied an optimal diagnostic algorithm reported a higher overall incidence of CDI (3.62 vs. 1.92, P < 0.001), and hospitals that were more active in searching for cases reported higher rates of hospital-acquired CDI (1.76 vs. 0.84, P < 0.001). The results suggest that the application of a multimodal training strategy was associated with a significant rise in the reporting of CDI, as well as with an increase in the application of the optimal diagnostic algorithm

MPC for tracking with optimal closed-loop performance

Abstract-This paper deals with the tracking problem for constrained linear systems using a model predictive control (MPC) law. As it is well known, MPC provides a control law suitable for regulating a constrained linear system to a given target steady state. Asymptotic stability and constraint fulfilment for any finite prediction horizon is typically ensured by means of a suitable choice of the terminal cost and constraint. However, when the target operating point changes, the feasibility of the controller may be lost and the controller fails to track the reference. Recently, a novel MPC formulation has been proposed to solve this problem, ensuring feasibility and asymptotic convergence to any admissible steady state. On the other hand, this control law can not ensure the local optimality of the proposed controller, which is a desirable property of predictive controllers. In this paper, this controller is extended considering a generalized offset cost function. Sufficient conditions on this function are given to ensure the local optimality property. Besides, this novel formulation allows to consider as target operation points, states which may be not equilibrium points of the linear systems. In this case, it is proved in this paper that the proposed control law steers the system to an admissible steady state (different to the target) which is optimal with relation to the offset cost function. Thanks to the proposed generalization, the offset cost function could be chosen according to some steady performance criterium. Therefore, the proposed controller for tracking achieves an optimal closed-loop performance during the transient as well as an optimal steady state in case of not admissible target. These properties are illustrated in an example

The Optical Design and Characterization of the Microwave Anisotropy Probe

The primary goal of the MAP satellite, now in orbit, is to make high fidelity polarization sensitive maps of the full sky in five frequency bands between 20 and 100 GHz. From these maps we will characterize the properties of the cosmic microwave background (CMB) anisotropy and Galactic and extragalactic emission on angular scales ranging from the effective beam size, <0.23 degree, to the full sky. MAP is a differential microwave radiometer. Two back-to-back shaped offset Gregorian telescopes feed two mirror symmetric arrays of ten corrugated feeds. We describe the prelaunch design and characterization of the optical system, compare the optical models to the measurements, and consider multiple possible sources of systematic error.Comment: ApJ in press; 22 pages with 11 low resolution figures; paper is available with higher quality figures at http://map.gsfc.nasa.gov/m_mm/tp_links.htm

The challenge of preparing teams for the European robotics league: Emergency

© 2017, Society for Imaging Science and Technology. ERL Emergency is an outdoor multi-domain robotic competition inspired by the 2011 Fukushima accident. The ERL Emergency Challenge requires teams of land, underwater and flying robots to work together to survey the scene, collect environmental data, and identify critical hazards. To prepare teams for this multidisciplinary task a series of summer schools and workshops have been arranged. In this paper the challenges and hands-on results of bringing students and researchers collaborating successfully in unknown environments and in new research areas are explained. As a case study results from the euRathlon/SHERPA workshop 2015 in Oulu are given