15,905 research outputs found
Normal and abnormal human vestibular ocular function
The major motivation of this research is to understand the role the vestibular system plays in sensorimotor interactions which result in spatial disorientation and motion sickness. A second goal was to explore the range of abnormality as it is reflected in quantitative measures of vestibular reflex responses. The results of a study of vestibular reflex measurements in normal subjects and preliminary results in abnormal subjects are presented in this report. Statistical methods were used to define the range of normal responses, and determine age related changes in function
Age-related changes in human posture control: Motor coordination tests
Postural responses to support surface displacements were measured in 214 normal human subjects ranging in age from 7 to 81 years. Motor tests measured leg muscle Electromyography (EMG) latencies, body sway, and the amplitude and timing of changes in center of pressure displacements in response to sudden forward and backward horizontal translations of the support surface upon which the subjects stood. There were small increases in both EMG latencies and the time to reach the peak amplitude of center of pressure responses with increasing age. The amplitude of center of pressure responses showed little change with age if the amplitude measures were normalized by a factor related to subject height. In general, postural responses to sudden translations showed minimal changes with age, and all age related trends which were identified were small relative to the variability within the population
Metrics that matter for assessing the ocean biological carbon pump
Ā© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Buesseler, K. O., Boyd, P. W., Black, E. E., & Siegel, D. A. Metrics that matter for assessing the ocean biological carbon pump. Proceedings of the National Academy of Sciences of the United States of America, (2020): 201918114, doi: 10.1073/pnas.1918114117.The biological carbon pump (BCP) comprises wide-ranging processes that set carbon supply, consumption, and storage in the oceansā interior. It is becoming increasingly evident that small changes in the efficiency of the BCP can significantly alter ocean carbon sequestration and, thus, atmospheric CO2 and climate, as well as the functioning of midwater ecosystems. Earth system models, including those used by the United Nationās Intergovernmental Panel on Climate Change, most often assess POC (particulate organic carbon) flux into the ocean interior at a fixed reference depth. The extrapolation of these fluxes to other depths, which defines the BCP efficiencies, is often executed using an idealized and empirically based flux-vs.-depth relationship, often referred to as the āMartin curve.ā We use a new compilation of POC fluxes in the upper ocean to reveal very different patterns in BCP efficiencies depending upon whether the fluxes are assessed at a fixed reference depth or relative to the depth of the sunlit euphotic zone (Ez). We find that the fixed-depth approach underestimates BCP efficiencies when the Ez is shallow, and vice versa. This adjustment alters regional assessments of BCP efficiencies as well as global carbon budgets and the interpretation of prior BCP studies. With several international studies recently underway to study the ocean BCP, there are new and unique opportunities to improve our understanding of the mechanistic controls on BCP efficiencies. However, we will only be able to compare results between studies if we use a common set of Ez-based metrics.We thank the many scientists whose ideas and contributions over the years are the foundation of this paper. This includes A. Martin, who led the organization of the BIARRITZ group (now JETZON) workshop in July 2019, discussions at which helped to motivate this article. We thank D. Karl for pointing us in the right direction for this paper format at PNAS and two thoughtful reviewers who through their comments helped to improve this manuscript. Support for writing this piece is acknowledged from several sources, including the Woods Hole Oceanographic Institutionās Ocean Twilight Zone project (K.O.B.); NASA as part of the EXport Processes in the global Ocean from RemoTe Sensing (EXPORTS) program (K.O.B. and D.A.S.). E.E.B. was supported by a postdoctoral fellowship through the Ocean Frontier Institute at Dalhousie University. P.W.B. was supported by the Australian Research Council through a Laureate (FL160100131)
A Survey of the Vocational Status of Eighty-Eight Graduates of Phillis Wheatley High School, Houston, Texas
For the last seven years the leading business men and women and educators of Texas have been engaged in a very important matter, known as a study of the curriculum of the high schools in this state. It was the original purpose of this conference to acquaint as many state educators as possible with significant phases of Negro Education in the Southwest . It was believed that this information concerning Negro education would serve as a stimulant to greater interest and more constructed activities. The creators of the conference, with Principal W. R. Banks of Prairie View College as head, further aimed to stimulate attitude toward Negro schools and therefore secure a more scientific basis for a program of improvement. The problems growing out of the deficiency of organization, equipment and personnel of the Negro schools of Texas had attracted the attention of these educators. This attraction was such that the State Department of Education, with county and city superintendents, Negroes and white members of school faculties and representatives of philanthropic foundations responded readily to the first call to conference on Negro education, April 11, 1930. In the meeting of this conference a General survey was made of Negro Rural Schools, high schools and colleges. The conditions of these schools were of such that the members of the conference unanimously voted to repeat the conference the next year.
Some said that the present high school curriculum is not suitable because it only prepares one to enter a college for liberal arts. We all know that we have at present, and for a long time to come, too many Negro men and women finishing college with only that which it takes to teach a few high school subjects. Knowing that the success of any nation or people depends very largely upon the occupational status of its individuals, it was advanced in one of the sessions of the vocational education group that many of the graduates who finish from the various high schools of Texas do not profit; because after finishing high school there is nothing for them to do in the line of making a living.
It was made plain that in order for the graduates who ere finishing high school every year to get a suitable position for making a tolerable living the high schools must change their curriculum at least partly to that of a technical one instead of liberal arts. In an effort to clear out the real solution to the problem, an idea was advanced to make a vocational status survey of the high schools of Texas. After studying the situation it was found that a special revised survey would not only furnish the public with the solution or standing of the vocational status of the graduates of the various high schools but would furnish other material pertaining to personal guidance, family, parents, marriages and the like. All of this information will help to find out just what the children of our race and state should be taught in the high schools.
Foot note- Proceedings of the Fifth Educational Conference. Bulletin July, 1934, Volume 26, No. 1. Published quarterly by Prairie View State College, Prairie View, Texas, pp. 8, Brief History of the Conference
Measurements of aerosol properties needed to infer backscatter characteristics in support of the NASA Doppler Lidar program
During the first year two areas of work were emphasized, analysis of aerosol data to provide improved estimates of backscatter over the Pacific ocean and development of a global model for backscatter at different wavelengths and preparation and planning for the aircraft flights of the GLOVE program. Significant progress was made in each of these areas. The analytical work is a continuation of the GAMETAG analysis, and was directed toward the development of a backscatter model for the Pacific Oceanic free troposphere. This has included a further evaluation of relationships between the optical effects at different wavelengths, a comparison of modeled optical effects at differing temporal resolutions, and an investigation of the effects of sampling on the modeled results. An initial investigation of the predictability of 9 to 10 micrometers Beta values from other data sets as well as some preliminary comparisons of the modeling results with experimental data. The comparison of the optical effects was extended to make the comparisons for different sets of time bases between 1 and 20 minutes
Phase-coherent repetition rate multiplication of a mode-locked laser from 40 MHz to 1 GHz by injection locking
We have used injection locking to multiply the repetition rate of a passively
mode-locked femtosecond fiber laser from 40 MHz to 1 GHz while preserving
optical phase coherence between the master laser and the slave output. The
system is implemented almost completely in fiber and incorporates gain and
passive saturable absorption. The slave repetition rate is set to a rational
harmonic of the master repetition rate, inducing pulse formation at the least
common multiple of the master and slave repetition rates
Infinite barbarians
This paper discusses an infinite regress that looms behind a certain kind of historical explanation. The movement of one barbarian group is often explained by the movement of others, but those movements in turn call for an explanation. While their explanation can again be the movement of yet another group of barbarians, if this sort of explanation does not stop somewhere we are left with an infinite regress of barbarians. While that regress would be vicious, it cannot be accommodated by several general views about what viciousness in infinite regresses amounts to. This example is additional evidence that we should prefer a pluralist approach to infinite regresses
Facilities and Methods Used in Full-scale Airplane Crash-fire Investigation
The facilities and the techniques employed in the conduct of full scale airplane crash-fire studies currently being conducted at the NACA Lewis laboratory are discussed herein. This investigation is part of a comprehensive study of the airplane crash-fire problem. The crash configuration chosen, the general physical layout of the crash site, the test methods, the instrumentation, the data-recording systems, and the post-crash examination procedure are describe
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