1,365 research outputs found
A Study of Maine Central Railroad Passenger Service Since 1900
A general study was made of the Maine Central railroad’s passenger service from 1900 to its elimination in I960. Because of the difficulties encountered in obtaining information regarding the Maine Central, the author has relied upon records of the Maine Public Utilities Commission and other sources.
The Maine Central Railroad once operated an extensive network of passenger trains. Additional services also included airlines, buslines, ferries, and hotels. As the popularity of the automobile increased, the railroad was forced to curtail its passenger service and end all operations of ferries, buses, and hotels. The number of passengers steadily declined, and passenger deficits endangered the financial position of the railroad.
Maine Central introduced articulated streamliners, reduced fares, and operated special trains to offset its losses. However, by 1954 officials began a major campaign to end all service. Several prominent Maine industries supported the railroad’s action in the hope of obtaining reduced freight rates. The last regularly scheduled passenger trains over Maine Central rails were operated on September 6, 1960. While the railroad was correct in arguing that the automobile and subsidized competition were responsible for passenger losses, Maine Central management was also to blame. Railroad buses directly competed with scheduled trains. After 1950 the quality of service rapidly declined, and little was done to promote passenger train travel.
The passenger train problem is national, and the Maine Central presented a special problem because of its geographical location and lack of many industries along its routes to provide adequate freight revenues. Future students of Maine railroad history must take this into consideration in order to understand the railroad’s problem. While many questions regarding Maine Central’s passenger service remain unanswered, it is hoped this study may provide a foundation for further research
Sinusoidal electromagnon in RMnO3: Indication of anomalous magnetoelectric coupling
The optical spectra in the family of multiferroic manganites RMnO3 is a great
puzzle. Current models can not explain the fact that two strong electromagnons
are present in the non-collinear spin cycloidal phase, with only one
electromagnon surviving the transition into the collinear spin sinusoidal
phase. We show that this is a signature of the presence of anomalous
magnetoelectric coupling that breaks rotational invariance in spin space and
generates oscillatory polarization in the ground state.Comment: 5 pages, 2 figure
Colored Speech: Cross Burnings, Epistemics, and the Triumph of the Crits?
This Essay examines the Court\u27s recent decision in Virginia v. Black. It argues that Black signifies a different approach to the constitutionality of statutes regulating cross burnings. It shows how the Court\u27s conservatives have essentially accepted the intellectual framework and the mode of analysis suggested previously by the critical race theorists. In particular, this Essay explores the role that Justice Thomas plays in the case. The Essay explains Justice Thomas\u27s active participation as a matter of epistemic authority and epistemic deference
Enhancement of electric and magnetic wave fields at density gradients
We use Freja satellite data to investigate irregular small-scale density variations. The observations are made in the auroral region at about 1000-1700 km. The density variations are a few percent, and the structures are found to be spatial down to a scale length of a few ion gyroradii. Irregular density variations are often found in an environment of whistler mode/lower hybrid waves and we show that at the density gradients both the electric and magnetic wave fields are enhanced
Use of near infrared reflectance spectroscopy to predict nitrogen uptake by winter wheat within fields with high variability in organic matter
In this study, the ability to predict N-uptake in winter wheat crops using NIR-spectroscopy on soil samples was evaluated. Soil samples were taken in unfertilized plots in one winter wheat field during three years (1997-1999) and in another winter wheat field nearby in one year (2000). Soil samples were analyzed for organic C content and their NIR-spectra. N-uptake was measured as total N-content in aboveground plant materials at harvest. Models calibrated to predict N-uptake were internally cross validated and validated across years and across fields. Cross-validated calibrations predicted N-uptake with an average error of 12.1 to 15.4 kg N ha-1. The standard deviation divided by this error (RPD) ranged between 1.9 and 2.5. In comparison, the corresponding calibrations based on organic C alone had an error from 11.7 to 28.2 kg N ha-1 and RPDs from 1.3 to 2.5. In three of four annual calibrations within a field, the NIR-based calibrations worked better than the organic C based calibrations. The prediction of N-uptake across years, but within a field, worked slightly better with an organic C based calibration than with a NIR based one, RPD = 1.9 and 1.7 respectively. Across fields, the corresponding difference was large in favour of the NIR-calibration, RPD = 2.5 for the NIR-calibration and 1.5 for the organic C calibration. It was concluded that NIR-spectroscopy integrates information about organic C with other relevant soil components and therefore has a good potential to predict complex functions of soils such as N-mineralization. A relatively good agreement of spectral relationships to parameters related to the N-mineralization of datasets across the world suggests that more general models can be calibrated
Monitoring and ming bio-physical parameters for hypoxia hazard in a coastal sand pit
Management of coastal areas requires monitoring and modeling of the anthropogenic drivers and the bio-physical processes affecting water quality. To assess the range of hydrographic conditions controlling oxygen distribution in the bottom layers of sand pits, a multi-year oceanographic survey has been conducted in a coastal area with several extraction pits. Hydrographic data including profiles of temperature, salinity and oxygen were collected and related to local wind conditions and circulation. Moreover, 1D and 3D high-resolution non-hydrostatic ocean models were used to describe turbulent mixing regimes and to obtain the range of wind speeds for which the critical anoxic conditions may occur. It is shown that wind speed appears to control the dynamics of oxygen concentrations, with oxygen depleted zones developing in a short time in low wind speed conditions. Moreover, the depth and the shape of the extraction pit contribute to decrease the mixing of the bottom layers and increase the water retention in the hole increasing the output and the persistence of oxygen depleted zones in the excavated area. The results of the numerical simulations show that the risk of hypoxia at the bottom of the sand pits is associated with higher temperatures and wind speed lower than 5 m/s, which is not infrequent during the summer season. However, the number of consecutive days of oxygen depletion can be considered lower than the danger threshold level assumed in the literature
Monitoring and Modelling Bio-Physical Parameters for Hypoxia Hazard in a Coastal Sand Pit
Management of coastal areas requires monitoring and modeling of the anthropogenic drivers and the bio-physical processes affecting water quality. To assess the range of hydrographic conditions controlling oxygen distribution in the bottom layers of sand pits, a multi-year oceanographic survey has been conducted in a coastal area with several extraction pits. Hydrographic data including profiles of temperature, salinity and oxygen were collected and related to local wind conditions and circulation. Moreover, 1D and 3D high-resolution non-hydrostatic ocean models were used to describe turbulent mixing regimes and to obtain the range of wind speeds for which the critical anoxic conditions may occur. It is shown that wind speed appears to control the dynamics of oxygen concentrations, with oxygen depleted zones developing in a short time in low wind speed conditions. Moreover, the depth and the shape of the extraction pit contribute to decrease the mixing of the bottom layers and increase the water retention in the hole increasing the output and the persistence of oxygen depleted zones in the excavated area. The results of the numerical simulations show that the risk of hypoxia at the bottom of the sand pits is associated with higher temperatures and wind speed lower than 5 m/s, which is not infrequent during the summer season. However, the number of consecutive days of oxygen depletion can be considered lower than the danger threshold level assumed in the literature
Oxygen Ion Energization Observed At High Altitudes
We present a case study of significant heating (up to 8 keV) perpendicular to
the geomagnetic field of outflowing oxygen ions at high altitude (12 RE)
above the polar cap. The shape of the distribution functions indicates that
most of the heating occurs locally (within 0.2–0.4 RE in altitude). This
is a clear example of local ion energization at much higher altitude than
usually reported. In contrast to many events at lower altitudes, it is not
likely that the locally observed wave fields can cause the observed ion
energization. Also, it is not likely that the ions have drifted from some
nearby energization region to the point of observation. This suggests that
additional fundamentally different ion energization mechanisms are present at
high altitudes. One possibility is that the magnetic moment of the ions is
not conserved, resulting in slower outflow velocities and longer time for ion
energization
Development of a cometosheath at comet 67P/Churuyumov-Gerasimenko: A case study comparison of Rosetta observations
Context: The ionosphere of a comet is known to deflect the solar wind through
mass loading, but the interaction is dependent on cometary activity. We
investigate the details of this process at comet 67P using the Rosetta Ion
Composition Analyzer. Aims: This study aims to compare the interaction of the
solar wind and cometary ions during two different time periods in the Rosetta
mission. Methods: We compared both the integrated ion moments (density,
velocity, and momentum flux) and the velocity distribution functions for two
days, four months apart. The velocity distribution functions were projected
into a coordinate system dependent on the magnetic field direction and averaged
over three hours. Results: The first case shows highly scattered H+ in both ion
moments and velocity distribution function. The He2+ ions are somewhat
scattered, but less so, and appear more like those of H2O+ pickup ions. The
second case shows characteristic evidence of mass-loading, where the solar wind
species are deflected, but the velocity distribution function is not
significantly changed. Conclusions: The distributions of H+ in the first case,
when compared to He2+ and H2O+ pickup ions, are indicative of a narrow
cometosheath on the scale of the H+ gyroradius. Thus, He2+ and H2O+, with
larger gyroradii, are largely able to pass through this cometosheath. An
examination of the momentum flux tensor suggests that all species in the first
case have a significant non-gyrotropic momentum flux component that is higher
than that of the second mass-loaded case. Mass loading is not a sufficient
explanation for the distribution functions and momentum flux tensor in the
first case, and so we assume this is evidence of bow shock formation.Comment: 14 pages, 9 figures, 3 tables, 2 video
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