Cruise noise of the 2/9th scale model of the Large-scale Advanced Propfan (LAP) propeller, SR-7A

Noise data on the Large-scale Advanced Propfan (LAP) propeller model SR-7A were taken in the NASA Lewis Research Center 8 x 6 foot Wind Tunnel. The maximum blade passing tone noise first rises with increasing helical tip Mach number to a peak level, then remains the same or decreases from its peak level when going to higher helical tip Mach numbers. This trend was observed for operation at both constant advance ratio and approximately equal thrust. This noise reduction or, leveling out at high helical tip Mach numbers, points to the use of higher propeller tip speeds as a possible method to limit airplane cabin noise while maintaining high flight speed and efficiency. Projections of the tunnel model data are made to the full scale LAP propeller mounted on the test bed aircraft and compared with predictions. The prediction method is found to be somewhat conservative in that it slightly overpredicts the projected model data at the peak

Ultrasonic imaging of textured alumina

Ultrasonic images representing the bulk attenuation and velocity of a set of alumina samples were obtained by a pulse-echo contact scanning technique. The samples were taken from larger bodies that were chemically similar but were processed by extrusion or isostatic processing. The crack growth resistance and fracture toughness of the larger bodies were found to vary with processing method and test orientation. The results presented here demonstrate that differences in texture that contribute to variations in structural performance can be revealed by analytic ultrasonic techniques

Interfacing Laboratory Instruments to Multiuser, Virtual Memory Computers

Computers based on virtual memory, multiuser architecture have recently become economically available to medium sized research groups (about 25 members). These new computers offer advantages to the experimentalist, though acceptance has been sometimes limited. One of the most important advantages of a virtual memory machine is the capability of fast access to arrays having dimensions greater than 64 kbytes. Arrays larger than 64 kbytes were available on some older computers based on physical memory. The access time to the memory beyond 64 kbytes is extremely slow for these systems. Fast access to large arrays is particularly important now where large data sets are required for research system

Systems for ultrasonic scanning, analysis and imagery

A variety of ultrasonic scanning and imagery techniques are used to investigate various aspects of materials and microstructures. Two ultrasonic scanning systems are in use by the Lewis Research Center's Structural Integrity Branch: an immersion scanner and a contact scanning system. The basic principles of scanning are reviewed, examples of images are presented, and structural features suggested by these images are discussed. Both of these systems are custom designed; their capabilities, advantages, and disadvantages are highlighted

Medication-Wide Association Studies

Undiscovered side effects of drugs can have a profound effect on the health of the nation, and electronic health-care databases offer opportunities to speed up the discovery of these side effects. We applied a “medication-wide association study” approach that combined multivariate analysis with exploratory visualization to study four health outcomes of interest in an administrative claims database of 46 million patients and a clinical database of 11 million patients. The technique had good predictive value, but there was no threshold high enough to eliminate false-positive findings. The visualization not only highlighted the class effects that strengthened the review of specific products but also underscored the challenges in confounding. These findings suggest that observational databases are useful for identifying potential associations that warrant further consideration but are unlikely to provide definitive evidence of causal effects

RETRACTED: Autoimmunity as the Consequence of a Spontaneous Mutation in Rasgrp1

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).This article has been retracted at the request of the Authors.The authors have agreed to retract the paper because of the falsification of the Western blot in Figure 6A. The figure shows a defect in Ras activation, labeled as RasGTP, following TCR engagement, in thymocytes isolated from a RasGRP1 lag mutant mouse strain. This data set is one of several that show signaling and functional deficiencies identified for cells with lost of function of RasGRP. The authors stand by the validity of the other figures, results and interpretation in this paper. This matter was investigated by the Massachusetts Institute of Technology and the Office of Research Integrity at the United States Department of Health & Human Services, which found the figure was falsified by Luk Van Parijs, who is solely responsible. The authors deeply regret any inconvenience resulting from the publication of this data

Early life factors, childhood cognition and postal questionnaire response rate in middle age: the Aberdeen Children of the 1950s study

BACKGROUND: Little is known about the relationship between early life factors and survey response in epidemiological studies of adults. METHODS: The Children of the 1950s cohort is composed of 12,150 children (boys 51.7%) born in Aberdeen 1950–56 and in primary schools in the city in 1962. Information on birth weight, gestational age, growth, behaviour and socio-economic position at birth and in childhood were obtained from contemporaneous records. Cognitive test scores at ages 7,9 and 11 years were also available from school records. The outcome was response to a postal questionnaire sent (2001–2003) to surviving cohort members in middle age. RESULTS: Of 11,282 potentially mailed subjects, 7,183 (63.7%) returned questionnaires. Response rates were highest among females, and those whose parents were married at birth, were in a non-manual social class at birth or in childhood, had fewer siblings, were taller and heavier in childhood for their age and had lower Rutter B behavioural scores. Childhood cognitive test scores at every age were strongly and positively related to the response rate to a postal questionnaire independently of other early life factors monotonically across the entire range of test scores. Those in the bottom fifth at age 11 had a response rate of 49% while those in the top fifth 75%. CONCLUSION: The strength and consistency of the association of childhood cognition with questionnaire response rate in middle age is surprisingly large. It suggests that childhood cognition across the entire normal range is a powerful influence on the complex set of later behaviours that comprise questionnaire response. The extent of possible response bias in epidemiological studies of the associations between childhood characteristics (particularly those related to cognition) and later health is probably larger than is generally realised, at least in situations where the survey instrument is a postal questionnaire