Design and evaluation of an integrated GPS/INS system for shallow-water AUV Navigation

The major problem addressed by this research is the large and/or expensive equipment required by a conventional navigation system to accurately determine the position of an Autonomous Underwater Vehicle (AUV) during all phases of an underwater search or mapping mission. The approach taken was to prototype an integrated navigation system which combines Global Positioning System (OPS) and Inertial Measurement Unit (IMU), waterspeed and heading information using Kalman filtering techniques. Actual implementation was preceded by a computer simulation to test where the unit would fit into a larger hardware and software hierarchy of an AUV. The system was then evaluated in experiments which began with land based cart tests and progressed to open water trials where the unit was placed in a towed body behind a boat and alternately submerged and surfaced to provide periodic OPS updates to the Inertial Navigation System (INS). Test results and qualitative error estimates indicate that submerged navigation accuracy comparable to that of differential OPS may be attainable for periods of 30 seconds or more with low cost components of a small physical size.http://archive.org/details/designndevaluati1094535102NANAU.S. Navy (U.S.N.) authors

Confidence and the Transmission of Government Spending Shocks

There seems to be a widespread belief among economists, policy-makers, and members of the media that the "confidence'" of households and businesses is a critical component in the transmission of fiscal policy shocks into economic activity. We take this proposition to the data using standard structural VARs with government spending and aggregate output augmented to include empirical measures of consumer or business confidence. We also estimate non-linear VAR specifications to allow for differential impacts of government spending in "normal'' times versus recessions. In normal times confidence does not react significantly to unexpected increases in government spending and spending multipliers are in the neighborhood of one; during recessions confidence rises and spending multipliers are significantly larger. We then quantify the importance of the systematic response of confidence to spending shocks for the spending multiplier and find that, in normal times, confidence is irrelevant for the transmission of government spending shocks to output, but during periods of economic slack it is important. We argue and present evidence that it is not confidence per se – in the sense of pure sentiment – that matters for the transmission of spending shocks during downturns, but rather that the composition of spending during a downtown is different. In particular, spending shocks during downturns predict future productivity improvements through a persistent increase in government investment relative to consumption, which is in turn reflected in higher measured confidence.

Uncertainty and Economic Activity: Evidence from Business Survey Data

What is the impact of time-varying business uncertainty on economic activity? Using partly confidential business survey data from the U.S. and Germany in structural VARs, we find that positive innovations to business uncertainty lead to prolonged declines in economic activity. In contrast, their high-frequency impact is small. We find no evidence of the "wait-and-see"-effect – large declines of economic activity on impact and subsequent fast rebounds – that the recent literature associates with positive uncertainty shocks. Rather, positive innovations to business uncertainty have effects similar to negative business confidence innovations. Once we control for their low-frequency effect, we find little statistically or economically significant impact of uncertainty innovations on activity. We argue that high uncertainty events are a mere epiphenomenon of bad economic times: recessions breed uncertainty.

Inertial and Magnetic Posture Tracking for Inserting Humans Into Networked Virtual Environments

Proceedings of ACM Symposium on Virtual Reality Software & Technology (VRST 2001), Banff, Alberta, Canada, 15 - 17 November 2001, pp.9-16.Accepted/Published Conference Pape

Effects of PACK guide training on the management of asthma and chronic obstructive pulmonary disease by primary care clinicians: a pragmatic cluster randomised controlled trial in Florianópolis, Brazil

Introduction The Practical Approach to Care Kit (PACK) guide was localised for Brazil, where primary care doctors and nurses were trained to use it. Methods Twenty-four municipal clinics in Florianópolis were randomly allocated to receive outreach training and the guide, and 24 were allocated to receive only the guide. 6666 adult patients with asthma or chronic obstructive pulmonary disease (COPD) were enrolled, and trial outcomes were measured over 12 months, using electronic medical records. The primary outcomes were composite scores of treatment changes and spirometry, and new asthma and COPD diagnosis rates. Results Asthma scores in 2437 intervention group participants were higher (74.8%, 20.4% and 4.8% with scores of 0, 1 and 2, respectively) than in 2633 control group participants (80.0%, 16.8% and 3.2%) (OR for higher score 1.32, 95% CI 1.08 to 1.61, p=0.006). Adjusted for asthma scores recorded in each clinic before training started, the OR was 1.24 (95% CI 1.03 to 1.50, p=0.022). COPD scores in 1371 intervention group participants (77.7%, 17.9% and 4.3% with scores of 0, 1 and 2) did not differ from those in 1181 control group participants (80.5%, 15.8% and 3.7%) (OR 1.21, 95% CI 0.94 to 1.55, p=0.142). Rates of new asthma and COPD diagnoses, and hospital admission, and indicators of investigation, diagnosis and treatment of comorbid cardiovascular disease, diabetes and depression, and tobacco cessation did not differ between trial arms. Conclusion PACK training increased guideline-based treatment and spirometry for asthma but did not affect COPD or comorbid conditions, or diagnosis rates

Task shifting and integration of HIV care into primary care in South Africa: The development and content of the streamlining tasks and roles to expand treatment and care for HIV (STRETCH) intervention

Background: Task shifting and the integration of human immunodeficiency virus (HIV) care into primary care services have been identified as possible strategies for improving access to antiretroviral treatment (ART). This paper describes the development and content of an intervention involving these two strategies, as part of the Streamlining Tasks and Roles to Expand Treatment and Care for HIV (STRETCH) pragmatic randomised controlled trial. Methods: Developing the intervention: The intervention was developed following discussions with senior management, clinicians, and clinic staff. These discussions revealed that the establishment of separate antiretroviral treatment services for HIV had resulted in problems in accessing care due to the large number of patients at ART clinics. The intervention developed therefore combined the shifting from doctors to nurses of prescriptions of antiretrovirals (ARVs) for uncomplicated patients and the stepwise integration of HIV care into primary care services. Results: Components of the intervention: The intervention consisted of regulatory changes, training, and guidelines to support nurse ART prescription, local management teams, an implementation toolkit, and a flexible, phased introduction. Nurse supervisors were equipped to train intervention clinic nurses in ART prescription using outreach education and an integrated primary care guideline. Management teams were set up and a STRETCH coordinator was appointed to oversee the implementation process. Discussion: Three important processes were used in developing and implementing this intervention: active participation of clinic staff and local and provincial management, educational outreach to train nurses in intervention sites, and an external facilitator to support all stages of the intervention rollout

Reply to: Low-frequency quantum oscillations in LaRhIn5_5: Dirac point or nodal line?

We thank G.P. Mikitik and Yu.V. Sharlai for contributing this note and the cordial exchange about it. First and foremost, we note that the aim of our paper is to report a methodology to diagnose topological (semi)metals using magnetic quantum oscillations. Thus far, such diagnosis has been based on the phase offset of quantum oscillations, which is extracted from a "Landau fan plot". A thorough analysis of the Onsager-Lifshitz-Roth quantization rules has shown that the famous $\pi$-phase shift can equally well arise from orbital- or spin magnetic moments in topologically trivial systems with strong spin-orbit coupling or small effective masses. Therefore, the "Landau fan plot" does not by itself constitute a proof of a topologically nontrivial Fermi surface. In the paper at hand, we report an improved analysis method that exploits the strong energy-dependence of the effective mass in linearly dispersing bands. This leads to a characteristic temperature dependence of the oscillation frequency which is a strong indicator of nontrivial topology, even for multi-band metals with complex Fermi surfaces. Three materials, Cd$_3$As$_2$, Bi$_2$O$_2$Se and LaRhIn$_5$ served as test cases for this method. Linear band dispersions were detected for Cd$_3$As$_2$, as well as the $F$ $\approx$ 7 T pocket in LaRhIn$_5$.Comment: Response to Matter arising for Nature Communications 12, 6213 (2021