5,573 research outputs found
The Rachel Carson Letters and the Making of Silent Spring
Environment, conservation, green, and kindred movements look back to Rachel Carsonâs 1962 book Silent Spring as a milestone. The impact of the book, including on government, industry, and civil society, was immediate and substantial, and has been extensively described; however, the provenance of the book has been less thoroughly examined. Using Carsonâs personal correspondence, this paper reveals that the primary source for Carsonâs book was the extensive evidence and contacts compiled by two biodynamic farmers, Marjorie Spock and Mary T. Richards, of Long Island, New York. Their evidence was compiled for a suite of legal actions (1957-1960) against the U.S. Government and that contested the aerial spraying of dichlorodiphenyltrichloroethane (DDT). During Rudolf Steinerâs lifetime, Spock and Richards both studied at Steinerâs Goetheanum, the headquarters of Anthroposophy, located in Dornach, Switzerland. Spock and Richards were prominent U.S. anthroposophists, and established a biodynamic farm under the tutelage of the leading biodynamics exponent of the time, Dr. Ehrenfried Pfeiffer. When their property was under threat from a government program of DDT spraying, they brought their case, eventually lost it, in the process spent US$100,000, and compiled the evidence that they then shared with Carson, who used it, and their extensive contacts and the trial transcripts, as the primary input for Silent Spring. Carson attributed to Spock, Richards, and Pfeiffer, no credit whatsoever in her book. As a consequence, the organics movement has not received the recognition, that is its due, as the primary impulse for Silent Spring, and it is, itself, unaware of this provenance
Next Generation NASA Hazard Detection System Development
The SPLICE project is continuing NASAs efforts to develop precision landing GN&C technologies for future lander missions. One of those technologies is the next generation Hazard Detection (HD) System, which consists of a new HD Lidar and HD Algorithms. The HD System is a modular system that will be adapted to meet specific mission needs in the future. This paper presents the design approach, the nominal concept of operations for which the first prototype is being designed, and the expected performance of the system
Use of linear discriminant function analysis in seed morphotype relationship study in 31 Lima bean (Phaseolus lunatus L.) accessions in Ghana
Variation in seed morphology of the Lima bean in 31 accessions was studied. Data were collected on 100-seed weight, seed length and seed width. The differences among the accessions were significant, based on the three seed characteristics. K-means cluster analysis grouped the 31 accessions into four distinct groups, representing four different morphotypes. Mahalanobis distances (D2) among the groups were highly significant. The four different morphotypes were attributed to the Mesoamerican gene pool, comprising the cultigroups Sieva-Big Lima, Potato-Sieva and Potato. Sub-cultigroups of the Sieva-Big Lima and Potato cultigroups due to differences in seed weight were suggested.Variation en morphologie de graine du haricot de Lima en trente accessions était étudiée. Des données étaient collectées sur poids de 100 graines, longueur de graine et largeur de graine. Il y avait des différences considérables parmi les accessions basées sur les trois caractéristiques de graine. Analyse du régime par K-moyens groupait les 31 accessions en quatre groupes distincts, représentant quatre morphotypes différents. Les distances (D2) Mahalanobis parmi les groupes étaient hautement considérables. Les quatre morphotypes différents étaient attribués au bagage héréditaire de Mesoaméricain, comprenant les groupes de cultures: Sieva-Grand Lima, Patate-Sieva et Patate. Les groupes de sous-cultures de Sieva-Grand Lima et Patate groupes de culture dû aux différences en poids de graine étaient suggérées. Ghana Journal of Agricultural Science Vol. 39 (1) 2006: pp. 87-9
Intra-individual movement variability during skill transitions: A useful marker?
Applied research suggests athletes and coaches need to be challenged in knowing when and how much a movement should be consciously attended to. This is exacerbated when the skill is in transition between two more stable states, such as when an already well learnt skill is being refined. Using existing theory and research, this paper highlights the potential application of movement variability as a tool to inform a coachâs decision-making process when implementing a systematic approach to technical refinement. Of particular interest is the structure of co-variability between mechanical degrees-of-freedom (e.g., joints) within the movement systemâs entirety when undergoing a skill transition. Exemplar data from golf are presented, demonstrating the link between movement variability and mental effort as an important feature of automaticity, and thus intervention design throughout the different stages of refinement. Movement variability was shown to reduce when mental effort directed towards an individual aspect of the skill was high (target variable). The opposite pattern was apparent for variables unrelated to the technical refinement. Therefore, two related indicators, movement variability and mental effort, are offered as a basis through which the evaluation of automaticity during technical refinements may be made
Quantum Fluctuations around the Electroweak Sphaleron
We present an analysis of the quantum fluctuations around the electroweak
sphaleron and calculate the associated determinant which gives the 1--loop
correction to the sphaleron transition rate. The calculation differs in various
technical aspects from a previous analysis by Carson et al. so that it can be
considered as independent. The numerical results differ also -- by several
orders of magnitude -- from those of this previous analysis; we find that the
sphaleron transition rate is much less suppressed than found previously.Comment: DO-TH-93/19 39 pages, 5 figures (available on request as Postscript
files or via Fax or mail), LaTeX, no macros neede
Open-Loop Flight Testing of COBALT GN&C Technologies for Precise Soft Landing
A terrestrial, open-loop (OL) flight test campaign of the NASA COBALT (CoOperative Blending of Autonomous Landing Technologies) platform was conducted onboard the Masten Xodiac suborbital rocket testbed, with support through the NASA Advanced Exploration Systems (AES), Game Changing Development (GCD), and Flight Opportunities (FO) Programs. The COBALT platform integrates NASA Guidance, Navigation and Control (GN&C) sensing technologies for autonomous, precise soft landing, including the Navigation Doppler Lidar (NDL) velocity and range sensor and the Lander Vision System (LVS) Terrain Relative Navigation (TRN) system. A specialized navigation filter running onboard COBALT fuzes the NDL and LVS data in real time to produce a precise navigation solution that is independent of the Global Positioning System (GPS) and suitable for future, autonomous planetary landing systems. The OL campaign tested COBALT as a passive payload, with COBALT data collection and filter execution, but with the Xodiac vehicle Guidance and Control (G&C) loops closed on a Masten GPS-based navigation solution. The OL test was performed as a risk reduction activity in preparation for an upcoming 2017 closed-loop (CL) flight campaign in which Xodiac G&C will act on the COBALT navigation solution and the GPS-based navigation will serve only as a backup monitor
One-loop corrections to the instanton transition in the two-dimensional Abelian Higgs model
We present an evaluation of the fluctuation determinant which appears as a
prefactor in the instanton transition rate for the two-dimensional Abelian
Higgs model. The corrections are found to change the rate at most by a factor
of 2 for 0.4 < M_W/M_H < 2.0.Comment: DO-TH-94/17, 20 pages, 4 figures appended as uucompressed .eps files,
LaTeX, needs epsfig.st
D-Dimensional Radiative Plasma: A Kinetic Approach
The covariant kinetic approach for the radiative plasma, a mixture of a
relativistic moving gas plus radiation quanta (photons, neutrinos, or
gravitons) is generalized to D spatial dimensions. The operational and physical
meaning of Eckart's temperature is reexamined and the D-dimensional expressions
for the transport coefficients (heat conduction, bulk and shear viscosity) are
explicitly evaluated to first order in the mean free time of the radiation
quanta. Weinberg's conclusion that the mixture behaves like a relativistic
imperfect simple fluid (in Eckart's formulation) depends neither on the number
of spatial dimensions nor on the details of the collisional term. The case of
Thomson scaterring is studied in detail, and some consequences for higher
dimensional cosmologies are also discussed.Comment: 28 pages, 1 figure, uses REVTE
Sphaleron Effects Near the Critical Temperature
We discuss one-loop radiative corrections to the sphaleron-induced baryon
number-violating transition rate near the electroweak phase transition in the
standard model. We emphasize that in the case of a first-order transition a
rearrangement of the loop expansion is required close to the transition
temperature. The corresponding expansion parameter, the effective 3-dimensional
gauge coupling approaches a finite dependent value at the critical
temperature.
The
(Higgs mass) dependence of the 1-loop radiative corrections is discussed in
the framework of the heat kernel method. Radiative corrections are small
compared to the leading sphaleron contribution as long as the Higgs mass is
small compared to the W mass. To 1-loop accuracy, there is no Higgs mass range
compatible with experimental limits where washing-out of a B+L asymmetry could
be avoided for the minimal standard model with one Higgs doublet.Comment: 17 pages, RevTeX, (4 figures in a separate uuencoded file),
HD-THEP-93-23re
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