554 research outputs found
The Influence of Tenure Status upon Rural Life in Eastern South Dakota
Introduction: The subject of land tenure has been of primary interest to South Dakota people for a number of years. Almost without exception, county agricultural planning committees have listed tenancy among the more important land-use problems in South Dakota. The State Agricultural Planning Committee at its February 1942, meeting requested that land tenure studies be continued by the South Dakota Agricultural Experiment Station. There has also been a considerable amount of interest in the problems of land tenure at the national level. An outstanding evidence of this concern is Farm Tendency, the report of the President’s Committee which was published in 1937. This report deals mainly with the problem of security for farmers, and in the preface it is made clear that “thousands of farmers commonly considered as owners are as insecure as tenants.” In the realm of governmental action the Farm Security Administration, acting under orders from the Congress, has helped some disadvantaged tenants to attain ownership. (See more in text)
A Measurement of Newton's Gravitational Constant
A precision measurement of the gravitational constant has been made using
a beam balance. Special attention has been given to determining the
calibration, the effect of a possible nonlinearity of the balance and the
zero-point variation of the balance. The equipment, the measurements and the
analysis are described in detail. The value obtained for G is 6.674252(109)(54)
10^{-11} m3 kg-1 s-2. The relative statistical and systematic uncertainties of
this result are 16.3 10^{-6} and 8.1 10^{-6}, respectively.Comment: 26 pages, 20 figures, Accepted for publication by Phys. Rev.
Time Variations of the Modulation of Anomalous and Galactic Cosmic Rays
Between the launch of the Advanced Composition Explorer (ACE) in 1997 and the end of 1999, the intensities of galactic cosmic rays at 1 AU have dropped almost a factor of 2, and the anomalous cosmic rays have decreased by an even larger amount. The large collecting power of the Cosmic Ray Isotope Spectrometer (CRIS) and the Solar Isotope Spectrometer (SIS) instruments on ACE allow us to investigate the changing modulation on short time scales and at different rigidities. Using anomalous cosmic ray (ACR) and galactic cosmic ray (OCR) intensities of He,
C, O, Ne, Si, S, and Fe, and energies from ~ 6 MeV/nucleon to ~ 460 MeV/nucleon, we examine the differences between the short term and long term effects. We observe the expected correlation of these intensities with neutron
monitor data, but see little correlation of OCR and ACR intensities with the locally measured magnetic field
Rapidly detecting disorder in rhythmic biological signals: A spectral entropy measure to identify cardiac arrhythmias
We consider the use of a running measure of power spectrum disorder to
distinguish between the normal sinus rhythm of the heart and two forms of
cardiac arrhythmia: atrial fibrillation and atrial flutter. This spectral
entropy measure is motivated by characteristic differences in the spectra of
beat timings during the three rhythms. We plot patient data derived from
ten-beat windows on a "disorder map" and identify rhythm-defining ranges in the
level and variance of spectral entropy values. Employing the spectral entropy
within an automatic arrhythmia detection algorithm enables the classification
of periods of atrial fibrillation from the time series of patients' beats. When
the algorithm is set to identify abnormal rhythms within 6 s it agrees with
85.7% of the annotations of professional rhythm assessors; for a response time
of 30 s this becomes 89.5%, and with 60 s it is 90.3%. The algorithm provides a
rapid way to detect atrial fibrillation, demonstrating usable response times as
low as 6 s. Measures of disorder in the frequency domain have practical
significance in a range of biological signals: the techniques described in this
paper have potential application for the rapid identification of disorder in
other rhythmic signals.Comment: 11 page
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HDAC9 is implicated in atherosclerotic aortic calcification and affects vascular smooth muscle cell phenotype.
Aortic calcification is an important independent predictor of future cardiovascular events. We performed a genome-wide association meta-analysis to determine SNPs associated with the extent of abdominal aortic calcification (n = 9,417) or descending thoracic aortic calcification (n = 8,422). Two genetic loci, HDAC9 and RAP1GAP, were associated with abdominal aortic calcification at a genome-wide level (P < 5.0 × 10-8). No SNPs were associated with thoracic aortic calcification at the genome-wide threshold. Increased expression of HDAC9 in human aortic smooth muscle cells promoted calcification and reduced contractility, while inhibition of HDAC9 in human aortic smooth muscle cells inhibited calcification and enhanced cell contractility. In matrix Gla protein-deficient mice, a model of human vascular calcification, mice lacking HDAC9 had a 40% reduction in aortic calcification and improved survival. This translational genomic study identifies the first genetic risk locus associated with calcification of the abdominal aorta and describes a previously unknown role for HDAC9 in the development of vascular calcification
Cyclotron radiation emission spectroscopy signal classification with machine learning in project 8
The cyclotron radiation emission spectroscopy (CRES) technique pioneered by Project 8measures electromagnetic radiation fromindividual electrons gyrating in a backgroundmagnetic field to construct a highly precise energy spectrumfor beta decay studies and other applications. The detector,magnetic trap geometry and electron dynamics give rise to amultitude of complex electron signal structures which carry information about distinguishing physical traits.Withmachine learningmodels, we develop a scheme based on these traits to analyze and classifyCRES signals. Proper understanding and use of these traits will be instrumental to improve cyclotron frequency reconstruction and boost the potential of Project 8 to achieveworld-leading sensitivity on the tritiumendpointmeasurement in the future
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