Power control circuit

Power control switching circuit using low voltage semiconductor controlled rectifiers for high voltage isolatio

The 30-cm ion thruster power processor

A power processor unit for powering and controlling the 30 cm Mercury Electron-Bombardment Ion Thruster was designed, fabricated, and tested. The unit uses a unique and highly efficient transistor bridge inverter power stage in its implementation. The system operated from a 200 to 400 V dc input power bus, provides 12 independently controllable and closely regulated dc power outputs, and has an overall power conditioning capacity of 3.5 kW. Protective circuitry was incorporated as an integral part of the design to assure failure-free operation during transient and steady-state load faults. The implemented unit demonstrated an electrical efficiency between 91.5 and 91.9 at its nominal rated load over the 200 to 400 V dc input bus range

Constrictive pericarditis and rheumatoid nodules with severe aortic incompetence.

The case of a female patient presenting with constrictive rheumatoid pericarditis and aortic incompetence secondary to valvular rheumatoid nodules is described along with a review of the literature with the aim to highlight this rare cause of aortic insufficiency

Mesospheric Temperature Climatology at the USU/CASS Atmospheric Lidar Observatory (ALO)

The Center for Atmospheric and Space Sciences (CASS) at Utah State University (USU) operates the ALO for the study of the middle atmosphere. Mesospheric observations between 45 and 90 km have been carried out on an observe when possible philosophy at night from 1993 to present. The location of ALO is unique as its mid-latitude location places it well within the Rocky Mountains which are a major orographic source for gravity waves. The lidar facility is located on the Utah State University campus, where it is very accessible to students. The relative observations from the lidar are reduced to provide absolute temperature profiles, which are important for understanding the physics and chemistry of the middle atmosphere. The temperature profiles were used to create a multi-year temperature climatology to examine secular, annual, seasonal variations, to compare with other temperature observations, and with modeled temperatures

An Earlier Lidar Observation of a Noctilucent Cloud above Logan, Utah (41.7º N, 111.8º W)

A Rayleigh-scatter lidar has been operated at the Atmospheric Lidar Observatory (ALO) on the Utah State University (USU) campus (41.7º N, 111.8º W) for the last 11 years. During the morning of 22 June 1995 a noctilucent cloud (NLC) was observed with the lidar, for approximately one hour, well away from the twilight periods when NLCs are visible. This sighting of an NLC at this latitude shows that the first sighting in 1999 [Wickwar et al., 2002] was not a unique occurrence. This 1995 observation differs from the 1999 one in that temperatures could be deduced. The hourly profiles are at least 20 K cooler than the 11-year June climatology for ALO near the NLC altitude. However, the cool temperatures arose because of a major temperature oscillation or wave, not because the whole profile was cooler. These lidar observations were supplemented by OH rotational observations from approximately 87 km, which also showed unusually cold temperatures on this night. While these NLC observations equatorward of 50° may be significant harbingers of global change, the mechanism is more complicated than a simple overall cooling or increase in water vapor

Atmospheric Lidar Observatory (ALO) Ten-Year Mesospheric Temperature Climatology

The Rayleigh-scatter lidar at the Atmospheric Lidar Observatory (ALO) on the Utah State University (USU) (41.7°N, 111.8°W) campus has been in operation since 1993. The temperature database now contains over ten years of Rayleigh-scatter temperatures. A multi-year temperature climatology has been calculated from these observations along with the RMS and interannual variability. These temperatures and the climatology are currently being used in a number of mesospheric studies, including mesospheric inversion layers, tides, planetary waves, cyclical variations, trends, longitudinal comparisons, and validation studies

Mid-Latitude Climatologies of Mesospheric Temperature and Geophysical Temperature Variability Determined with the Rayleigh-Scatter Lidar at ALO-USU

From 1993-2004, 839 nights were observed with the Rayleigh-scatter lidar at Utah State University’s Atmospheric Lidar Observatory. They were reduced to obtain nighttime mesospheric temperatures between 45 and ~90 km, which were then combined to derive composite annual climatologies of mid-latitude temperatures and geophysical temperature variability. At 45 km, near the stratopause, there is a ~250 K temperature minimum in mid-winter and a 273 K maximum in mid-May. The variability behaves oppositely, being 7-10 K in winter and 2.5 K in summer. At 85 km, there is a 215 K temperature maximum at the end of December and a 170 K mesopause minimum in early June. In contrast, the variability is roughly constant at ~20 K. At both low and high altitudes, the temperatures change much more rapidly in spring than in fall. The transition between these opposite temperature behaviors is 65 km. Distinctive temperature structures occur in all regions. In mid-winter, between 45 and 50 km, a 6 K warm region appears, most likely from occasional sudden stratospheric warmings. Above that, a “cold valley” extends to 70 km, which may be related to the bottom side of intermittent inversion layers. Both regions have increased variability. Near 85 km, there is a very rapid heating event of 25 K/month in August with high variability. In October, a temperature minimum, a “cold island”, occurs from 78–86 km with low variability, indicating a regular feature. These USU results are compared extensively to those from other mid-latitude lidars in Canada and France

Advancing the digital and computational capabilities of healthcare providers: A qualitative study of a hospital organisation in the NHS

Objective: Healthcare systems require transformation to meet societal challenges and projected health demands. Digital and computational tools and approaches are fundamental to this transformation, and hospitals have a key role to play in their development and implementation. This paper reports on a study with the objective of exploring the challenges encountered by hospital leaders and innovators as they implement a strategy to become a data-driven hospital organisation. In doing so, this paper provides guidance to future leaders and innovators seeking to build computational and digital capabilities in complex clinical settings. Methods: Interviews were undertaken with 42 participants associated with a large public hospital organisation within England's National Health Service. Using the concept of institutional readiness as an analytical framework, the paper explores participants’ perspectives on the organisation's capacity to support the development of, and benefit from, digital and computational approaches. Results: Participants’ accounts reveal a range of specific institutional readiness criteria relating to organisational vision, technical capability, organisational agility, and talent and skills that, when met, enhance the organisations’ capacity to support the development and implementation of digital and computational tools. Participant accounts also reveal challenges relating to these criteria, such as unrealistic expectations and the necessary prioritisation of clinical work in resource-constrained settings. Conclusions: The paper identifies a general set of institutional readiness criteria that can guide future hospital leaders and innovators aiming to improve their organisation's digital and computational capability. The paper also illustrates the challenges of pursuing digital and computational innovation in resource-constrained hospital environments