10,800 research outputs found
Multiple spacecraft observations of interplanetary shocks: Characteristics of the upstream ULF turbulence
All interplanetary shocks observed by ISEE-3 and either ISEE-1 or ISEE-2 or both in 1978 and 1979 are examined for evidence of upstream waves. In order to characterize the properties of these shocks it is necessary to determine accurate shock normals. An overdetermined set of equations were inverted to obtain shock normals, velocities and error estimates for all these shocks. Tests of the method indicate it is quite reliable. Using these normals the Mach number and angle were between the interplanetary magnetic field and the shock normal for each shock. The upstream waves were separated into two classes: whistler mode precursors which occur at low Mach numbers and upstream turbulence whose amplitude at Mach numbers greater than 1.5 is controlled by the angle of the field to the shock normal. The former waves are right hand circularly polarized and quite monochromatic. The latter waves are more linearly polarized and have a broadband featureless spectrum
OGO-3 observations of ELF noise in the magnetosphere - Part 1 - Spatial extent and frequency of occurrence
OGO-3 spectrum analyzer measurements of magnetic noise in magnetospher
Analysis of polyubiquitin conjugates reveals that the Rpn10 substrate receptor contributes to the turnover of multiple proteasome targets
The polyubiquitin receptor Rpn10 targets ubiquitylated Sic1 to the 26S proteasome for degradation. In contrast, turnover of at least one ubiquitin-proteasome system (UPS) substrate, CPY*, is impervious to deletion of RPN10. To distinguish whether RPN10 is involved in the turnover of only a small set of cell cycle regulators that includes Sic1 or plays a more general role in the UPS, we sought to develop a general method that would allow us to survey the spectrum of ubiquitylated proteins that selectively accumulate in rpn10 cells. Polyubiquitin conjugates from yeast cells that express hexahistidine-tagged ubiquitin (H6-ubiquitin) were first enriched on a polyubiquitin binding protein affinity resin. This material was then denatured and subjected to IMAC to retrieve H6-ubiquitin and proteins to which it may be covalently linked. Using this approach, we identified 127 proteins that are candidate substrates for the 26S proteasome. We then sequenced ubiquitin conjugates from cells lacking Rpn10 (rpn10) and identified 54 proteins that were uniquely recovered from rpn10 cells. These include two known targets of the UPS, the cell cycle regulator Sic1 and the transcriptional activator Gcn4. Our approach of comparing the ubiquitin conjugate proteome in wild-type and mutant cells has the resolving power to identify even an extremely inabundant transcriptional regulatory protein and should be generally applicable to mapping enzyme substrate networks in the UPS
On the use of a sunward-libration-point orbiting spacecraft as an IMF monitor for magnetospheric studies
Magnetospheric studies often require knowledge of the orientation of the IMF. In order to test the accuracy of using magnetometer data from a spacecraft orbiting the sunward libration point for this purpose, the angle between the IMF at ISEE 3, when it was positioned around the libration point, and at ISEE 1, orbiting Earth, has been calculated for a data set of two-hour periods covering four months. For each period, a ten-minute average of ISEE 1 data is compared with ten-minute averages of ISEE 3 data at successively lagged intervals. At the lag time equal to the time required for the solar wind to convect from ISEE 3 to ISEE 1, the median angle between the IMF orientation at the two spacecraft is 20 deg, and 80% of the cases have angles less than 38 deg. The results for the angles projected on the y-z plane are essentially the same
ATMOS Spacelab 1 science investigation
Existing infrared spectra from high speed interferometer balloon flights were analyzed and experimental analysis techniques applicable to similar data from the ATMOS experiment (Spacelab 3) were investigated. Specific techniques under investigation included line-by-line simulation of the spectra to aid in the identification of absorbing gases, simultaneous retrieval of pressure and temperature profiles using carefully chosen pairs of CO2 absorption lines, and the use of these pressures and temperatures in the retrieval of gas concentration profiles for many absorbing species. A search for a new absorption features was also carried out, and special attention was given to identification of absorbing gases in spectral bandpass regions to be measured by the halogen occultation experiment
Global auroral responses to magnetospheric compressions by shocks in the solar wind: Two case studies
The global auroral responses to shocks in the solar wind at Earth were studied. The z-component of the interplanetary magnetic field, Bz, is negative ahead and behind the first shock and positive for the second case. A sudden-commencement geomagnetic storm develops in each case, with maximum D sub st 190 nT. An immediate auroral response is detected at all longitudes around the auroral oval, in which auroral luminosities increase by a factor of 2 to 3 with the first samples after each sudden commencement. The time delay in obtaining the first sample varies with local time from approx. 1 to 18 mins. No other significant variations in the aurora are associated with the immediate response. Beginning approx. 30 mins after each sudden commencement, the aurora becomes active and displays significant variations in its luminosity and spatial distribution. For Bz 0 an intense substorm develops. A sun-aligned transpolar arc forms when Bz 0, appearing first at local midnight as a polar arc and then lengthening sunward from the auroral oval across the polar cap to noon at an average speed of approx. 1 km/sec
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Methyl hydrazinocarboxylate as a practical alternative to hydrazine in the Wolff–Kishner reaction
Herein we describe a facile protocol for the reduction of aromatic ketones and aldehydes to the corresponding methylene unit. The procedure involves isolation of a carbomethoxyhydrazone intermediate that is easily decomposed to the reduced product without the requirement
for large quantities of pernicious hydrazine
Structural Definition and Mass Estimation of Lunar Surface Habitats for the Lunar Architecture Team Phase 2 (LAT-2) Study
The Lunar Architecture Team Phase 2 study defined and assessed architecture options for a Lunar Outpost at the Moon's South Pole. The Habitation Focus Element Team was responsible for developing concepts for all of the Habitats and pressurized logistics modules particular to each of the architectures, and defined the shapes, volumes and internal layouts considering human factors, surface operations and safety requirements, as well as Lander mass and volume constraints. The Structures Subsystem Team developed structural concepts, sizing estimates and mass estimates for the primary Habitat structure. In these studies, the primary structure was decomposed into a more detailed list of components to be sized to gain greater insight into concept mass contributors. Structural mass estimates were developed that captured the effect of major design parameters such as internal pressure load. Analytical and empirical equations were developed for each structural component identified. Over 20 different hard-shell, hybrid expandable and inflatable soft-shell Habitat and pressurized logistics module concepts were sized and compared to assess structural performance and efficiency during the study. Habitats were developed in three categories; Mini Habs that are removed from the Lander and placed on the Lunar surface, Monolithic habitats that remain on the Lander, and Habitats that are part of the Mobile Lander system. Each category of Habitat resulted in structural concepts with advantages and disadvantages. The same modular shell components could be used for the Mini Hab concept, maximizing commonality and minimizing development costs. Larger Habitats had higher volumetric mass efficiency and floor area than smaller Habitats (whose mass was dominated by fixed items such as domes and frames). Hybrid and pure expandable Habitat structures were very mass-efficient, but the structures technology is less mature, and the ability to efficiently package and deploy internal subsystems remains an open issue
Distinctive traditions at the College of William and Mary and their influence on the modernization of the college, 1865 to 1919
The purpose of this study was to trace the development of the relationship between the William and Mary College identity and its environment during the period 1865 to 1919. The pivotal point in the work was 1888, at which time the College experienced a revolutionary change in mission from liberal arts education to teacher training. The particular focus was on the effect of the change in mission on the set of historical traditions that constituted a major proportion of the institutional image and endowed the College with a distinctive identity.;The early achievements of the College in educating Thomas Jefferson and other Virginia statesmen furnished the school with a set of distinctive traditions that were based on outstanding institutional performance and a high level of public recognition. Between 1776 and 1861, however, William and Mary experienced modest budgets and was in many respects similar to the hundreds of other small colleges in the nation. The burning of the College and the destruction of most of its endownment during the Civil War nearly destroyed the institution. Because of the inability of the school to recover from the Civil War as a liberal arts college, the Board adopted a revolutionary change in curriculum in 1888. The school was converted into a teacher-training institution in order to secure an appropriation from the Virginia legislature that would preserve the institution.;In the thesis of the study, it was proposed that the officers of the College placed great emphasis on the historical traditions of the the adoption of the teacher-training mission. at that time, the aristocratic leaders of the Commonwealth opposed the development and expansion of the public schools and normal schooling. But many of the most notable Virginia leaders expressed great admiration for heroic pre-Civil War traditions such as those possessed by William and Mary.;By establishing a public identity based largely on its ante bellum traditions, the leaders of the College attempted to endow the school with an image that would (1) attract generous public benevolence and (2) inspire the students to develop high-minded and productive lives.;It was found that the unique ethos established by the College tradition was partly successful in achieving the desired goals. Legislators, wealthy individuals, and foundation officials for the most part were not inspired by the institutional tradition. . . . (Author\u27s abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI
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Emission estimates of selected volatile organic compounds from tropical savanna burning in northern Australia
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