Single-event effects in resolver-to-digital converters

Single-event effects (SEEs) in two resolver-to-digital converters (RDCs) have been studied using heavy ions and pulsed laser light. The important role of the pulsed laser in establishing single-event upset (SEU) and single-event latchup (SEL) levels prior to accelerator testing is described, as is its role in evaluating the test software and hardware and in gaining a better understanding of the origins of the SEEs. Results from pulsed-laser testing are in quantitative agreement with those from heavy-ion testing: the RDC-19220 is sensitive to both SEUs and SELs whereas the AD2S80 is less sensitive to SEUs and immune to SEL     

A nonlinear least-squares method for determining cerebrospinal fluid formation and absorption kinetics in pseudotumor cerebri

Data from 14 patients with benign intracranial hypertension (pseudotumor cerebri) have been analyzed using a nonlinear least-squares regression model which was developed and programmed from in-hospital microcomputer use. The method of analysis permits rapid estimation of cerebrospinal fluid (CSF) formation and absorption rates as functions of pressure in individual patients using data from constant-rate infusion manometrics. The analysis predicts that prednisone therapy in pseudotumor cerebri reduces resting CSF pressure by increasing CSF absorption at all intracranial pressures studied, and decreasing CSF formation at high pressures. This result is in accordance with evidence suggesting that impaired CSF absorption plays a major role in the pathogenesis of increased intracranial pressure in pseudotumor cerebri.     

The Gator Tech Smart House: a programmable pervasive space

Research groups in both academia and industry have developed prototype systems to demonstrate the benefits of pervasive computing in various application domains. Unfortunately, many first-generation pervasive computing systems lack the ability to evolve as new technologies emerge or as an application domain matures. To address this limitation, the University of Florida's Mobile and Pervasive Computing Laboratory is developing programmable pervasive spaces in which a smart space exists as both a runtime environment and a software library. Service discovery and gateway protocols automatically integrate system components using generic middleware that maintains a service definition for each sensor and actuator in the space. The Gator Tech Smart House in Gainesville, Florida, is the culmination of more than five years of research in pervasive and mobile computing. The project's goal is to create assistive environments such as homes that can sense themselves and their residents and enact mappings between the physical world and remote monitoring and intervention services.     

The effects of disjunct sampling and averaging time on maximum mean wind speeds

Conventionally, the 50-year wind is calculated on basis of the annual maxima of consecutive 10-min averages. Very often, however, the averages are saved with a temporal spacing of several hours. We call it disjunct sampling. It may also happen that the wind speeds are averaged over a longer time period before being saved. In either case, the extreme wind will be underestimated. This paper investigates the effects of the disjunct sampling interval and the averaging time on the attenuation of the extreme wind estimation by means of a simple theoretical approach as well as measurements. The measurements include climates dominated by extratropical lows, as well as more complicated, wind climate types. For both, the investigations are done for omni-directional and sector-wise situations. The theory assumes the time series is a Gaussian Markov chain and it performs adequately for sites in the extratropical regions. The sector-wise situation is more complicated. The attenuation of the extreme mean winds for a sector shows a dependency on the frequency of occurrence from that sector.     

Regulation and regulatory role of gamma-carboxyglutamic acid containing clotting factors

Several investigators have recently reported that significant numbers of appropriately adapted mutants can be induced in bacterial and yeast strains by exposing stationary phase cells to specific environmental challenges. The resulting mutants are said to be both selection-induced and demonstrably non-random in origin; if this interpretation is correct, it is in direct conflict with the conventional neo-Darwinian view, which is that spontaneous mutants are truly random in origin and arise without the intervention of any overtly adaptive forces. We believe that there are alternative ways of accounting for the appearance of many (and probably all) of the additional mutants which proponents of the adaptive mutation theory claim are observed only after they applied the appropriate selective pressure. Having reviewed the available evidence, we consider that most (if not all) of the sorts of mutants which are said to have been induced following exposure of stationary-phase cells to intense selective pressure are equally likely to have been generated during the operation of certain well-known, conventional (and essentially random) cellular DNA repair processes. Evidence in support of our view can be found in the mainstream literature on the origins of spontaneous mutations. We also note that some of the molecular models which have recently been proposed to explain the production of selection-induced mutations preferentially (or even only) in genes of adaptive significance may turn out to be of considerable interest in their own right, even although the mutants whose origins they were intended to explain may turn out to have arisen in a manner which is totally independent of the conditions used for their selection.     

Stability of up-milling and down-milling, part 2: experimental verification

The stability of interrupted cutting in a single degree of freedom milling process was studied experimentally. An instrumented flexure was used to provide a flexible workpiece with a natural frequency comparable to the tooth pass frequency, mimicking high speed milling dynamics. The displacement of the system was sampled continuously and periodically once per cutter revolution. These data samples were used to asses the stability of the system. Results confirm the theoretical predictions obtained in Part 1.