541 research outputs found
An interpretation of philosophy and aesthetics for contemporary music education
Thesis (D.M.A)--Boston University
N.B. Page 237 misnomeredWhen traced culturally, the history of music education in the United States reveals certain shiftings of emphasis from the religious (1625-l770) through the political (1770-1860) and the utilitarian eras (1860-1920) towards the motives of mass education (from 1920).(148:174) More recent trends indicate the emergence of the musical arts and music education as an integral aesthetic component of contemporary culture. The broadening interests in general education have stimulated the gradual promotion and clarification of such desirable democratic goals as equality of opportunity, child-centered interests, and the breakdown of parochialistic attitudes and ethnocentric tendencies. Ever since the efforts of Mason and others in introducing music into the public schools, the music education profession has made forward-looking strides to clarify objectives, to stimulate more effective teaching pedagogy, to improve standards, to broaden the horizons of music education, and to establish a working rapport with the social sciences. As a result of new concepts in changing society, important anti-thetical issues have risen from a great tradition of private and public school teaching, and have found more significant meanings in closer relations with the school, the home, and the community. These basic problems in both professional and amateur music are most crucial to the music educator today, in view of new leisure time patterns, technological advances; economic and political pressures, population growth, and the development of mass media in communication. [TRUNCATED
The CRaTER Special Issue of Space Weather: Building the observational foundation to deduce biological effects of space radiation
[1] The United States is preparing for exploration beyond low-Earth Orbit (LEO). However, the space radiation environment poses significant risks. The radiation hazard is potentially severe but not sufficiently well characterized to determine if long missions outside LEO can be accomplished with acceptable risk [Cucinotta et al., 2001; Schwadron et al., 2010; Cucinotta et al., 2010]. Radiation hazards may be over- or under-stated through incomplete characterization in terms of net quantities such as accumulated dose. Time-dependent characterization often changes acute risk estimates [NCRP, 1989; Cucinotta, 1999; Cucinotta et al., 2000; George et al., 2002]. For example, events with high accumulated doses but sufficiently low dose rates (/h) pose significantly reduced risks. Protons, heavy ions, and neutrons all contribute significantly to the radiation hazard. However, each form of radiation presents different biological effectiveness. As a result, quality factors and radiation-specific weighting factors are needed to assess biological effectiveness of different forms of radiation [e.g., NCRP 116, 1993] (Figure 1). More complete characterization must account for time-dependent radiation effects according to organ type, primary and secondary radiation composition, and acute effects (vomiting, sickness, and, at high exposures, death) versus chronic effects (such as cancer)
Energy dissipation and ion heating at the heliospheric termination shock
The Los Alamos hybrid simulation code is used to examine heating and the partition of dissipation energy at the perpendicular heliospheric termination shock in the presence of pickup ions. The simulations are one-dimensional in space but three-dimensional in field and velocity components, and are carried out for a range of values of pickup ion relative density. Results from the simulations show that because the solar wind ions are relatively cold upstream, the temperature of these ions is raised by a relatively larger factor than the temperature of the pickup ions. An analytic model for energy partition is developed on the basis of the Rankine-Hugoniot relations and a polytropic energy equation. The polytropic index gamma used in the Rankine-Hugoniot relations is varied to improve agreement between the model and the simulations concerning the fraction of downstream heating in the pickup ions as well as the compression ratio at the shock. When the pickup ion density is less than 20%, the polytropic index is about 5/3, whereas for pickup ion densities greater than 20%, the polytropic index tends toward 2.2, suggesting a fundamental change in the character of the shock, as seen in the simulations, when the pickup ion density is large. The model and the simulations both indicate for the upstream parameters chosen for Voyager 2 conditions that the pickup ion density is about 25% and the pickup ions gain the larger share ( approximately 90%) of the downstream thermal pressure, consistent with Voyager 2 observations near the shock
A possible generation mechanism for the IBEX ribbon from outside the heliosphere
The brightest and most surprising feature in the first all-sky maps of
Energetic Neutral Atoms (ENA) emissions (0.2-6 keV) produced by the
Interstellar Boundary Explorer (IBEX) is an almost circular ribbon of a
~140{\deg} opening angle, centered at (l,b) = (33{\deg}, 55{\deg}), covering
the part of the celestial sphere with the lowest column densities of the Local
Interstellar Cloud (LIC). We propose a novel interpretation of the IBEX results
based on the idea of ENA produced by charge-exchange between the neutral H
atoms at the nearby edge of the LIC and the hot protons of the Local Bubble
(LB). These ENAs can reach the Sun's vicinity because of very low column
density of the intervening LIC material. We show that a plane-parallel or
slightly curved interface layer of contact between the LIC H atoms (n_H = 0.2
cm^-3, T = 6000-7000 K) and the LB protons (n_p = 0.005 cm^-3, T ~ 10^6 K),
together with indirect contribution coming from multiply-scattered ENAs from
the LB, may be able to explain both the shape of the ribbon and the observed
intensities provided that the edge is < (500-2000) AU away, the LIC proton
density is (correspondingly) < (0.04-0.01) cm^-3, and the LB contains ~1% of
non-thermal protons over the IBEX energy range. If this model is correct, then
IBEX, for the first time, has imaged in ENAs a celestial object from beyond the
confines of the heliosphere and can directly diagnose the plasma conditions in
the LB.Comment: Accepted by Ap.J.Lett
Statistical acceleration of interstellar pick‐up ions in co‐rotating interaction regions
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94615/1/grl9663.pd
The radial evolution of solar wind speeds
The WSA-ENLIL model predicts significant evolution of the solar wind speed. Along a flux tube the solar wind speed at 1.0 AU and beyond is found to be significantly altered from the solar wind speed in the outer corona at 0.1 AU, with most of the change occurring within a few tenths of an AU from the Sun. The evolution of the solar wind speed is most pronounced during solar minimum for solar wind with observed speeds at 1.0 AU between 400 and 500 km/s, while the fastest and slowest solar wind experiences little acceleration or deceleration. Solar wind ionic charge state observations made near 1.0 AU during solar minimum are found to be consistent with a large fraction of the intermediate-speed solar wind having been accelerated or decelerated from slower or faster speeds. This paper sets the groundwork for understanding the evolution of wind speed with distance, which is critical for interpreting the solar wind composition observations near Earth and throughout the inner heliosphere. We show from composition observations that the intermediate-speed solar wind (400-500 km/s) represents a mix of what was originally fast and slow solar wind, which implies a more bimodal solar wind in the corona than observed at 1.0 AU
Role of coronal mass ejections in the heliospheric Hale cycle
[1] The 11-year solar cycle variation in the heliospheric magnetic field strength can be explained by the temporary buildup of closed flux released by coronal mass ejections (CMEs). If this explanation is correct, and the total open magnetic flux is conserved, then the interplanetary-CME closed flux must eventually open via reconnection with open flux close to the Sun. In this case each CME will move the reconnected open flux by at least the CME footpoint separation distance. Since the polarity of CME footpoints tends to follow a pattern similar to the Hale cycle of sunspot polarity, repeated CME eruption and subsequent reconnection will naturally result in latitudinal transport of open solar flux. We demonstrate how this process can reverse the coronal and heliospheric fields, and we calculate that the amount of flux involved is sufficient to accomplish the reversal within the 11 years of the solar cycle
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The heliospheric magnetic field over the Hale cycle
The concept that open magnetic flux of the Sun (rooted with one and only one footpoint at the Sun) is a conserved quantity is taking root in the heliospheric community. Observations show that the Sun's open magnetic flux returns to the baseline from one solar minimum to the next. The temporary enhancement in the 1 AU heliospheric magnetic flux near solar maximum can be accounted for by the temporary creation of closed magnetic flux (with two footpoints at the Sun) during the ejection of coronal mass ejections (CMEs), which are more frequent near solar maximum. As a part of the International Heliophysical Year activities, this paper reviews two recently discussed consequences of open flux conservation: the reversal of open magnetic flux over the solar cycle driven by Coronal Mass Ejections and the impacts of open flux conservation on the global structure of the heliospheric magnetic field. These studies demonstrate the inherent linkages between coronal mass ejections, footpoint motions back at the Sun, and the global structure and evolution of the heliospheric magnetic field
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