1,519 research outputs found
Implications to Consider in the Privatization of the City of Flint Ambulance Service
With decreased revenues and increased or constant demands for services state and local government units have examined a wide range of privatization alternatives. The most common of these alternatives has been the use of contracting for services. Contracting of services has been an alternative that has been utilized by an increasing percentage of municipalities as revenues have decreased. Data obtained from the City of Flint and various other sources were compared to illustrate implications that must be considered if a privatization effort of the municipal ambulance service was to be pursued. Implications that were examined concern economic factors, quality of service issues, social concerns, union and labor implications, legal issues, and political effects. The results of the examination indicate that 1) wage and fringe benefit packages offered to private sector employees were generally less than those received by comparable public employees; 2) competition would increase efficiency in the ambulance service; 3) the impact on minority individuals would be proportionate to the impact on the total work force; 4) labor and union negotiation is mandatory for an effort to succeed; 5) legal issues must be explored thoroughly as they pertain to the situation; and 6) political factors have an immense impact on the structure of the EMS service.Master of Public AdministrationPublic AdministrationUniversity of Michigan-Flinthttps://deepblue.lib.umich.edu/bitstream/2027.42/143467/1/Linker.pd
A Model for the Sources of the Slow Solar Wind
Models for the origin of the slow solar wind must account for two seemingly
contradictory observations: The slow wind has the composition of the closed
field corona, implying that it originates from the continuous opening and
closing of flux at the boundary between open and closed field. On the other
hand, the slow wind also has large angular width, up to ~ 60{\circ}, suggesting
that its source extends far from the open-closed boundary. We propose a model
that can explain both observations. The key idea is that the source of the slow
wind at the Sun is a network of narrow (possibly singular) open-field corridors
that map to a web of separatrices and quasi-separatrix layers in the
heliosphere. We compute analytically the topology of an open-field corridor and
show that it produces a quasi-separatrix layer in the heliosphere that extends
to angles far from the heliospheric current sheet. We then use an MHD code and
MDI/SOHO observations of the photospheric magnetic field to calculate
numerically, with high spatial resolution, the quasi-steady solar wind and
magnetic field for a time period preceding the August 1, 2008 total solar
eclipse. Our numerical results imply that, at least for this time period, a web
of separatrices (which we term an S-web) forms with sufficient density and
extent in the heliosphere to account for the observed properties of the slow
wind. We discuss the implications of our S-web model for the structure and
dynamics of the corona and heliosphere, and propose further tests of the model
May 12 1997 Cme Event: I. a Simplified Model of the Pre-Eruptive Magnetic Structure
A simple model of the coronal magnetic field prior to the CME eruption on May
12 1997 is developed. First, the magnetic field is constructed by superimposing
a large-scale background field and a localized bipolar field to model the
active region (AR) in the current-free approximation. Second, this potential
configuration is quasi-statically sheared by photospheric vortex motions
applied to two flux concentrations of the AR. Third, the resulting force-free
field is then evolved by canceling the photospheric magnetic flux with the help
of an appropriate tangential electric field applied to the central part of the
AR.
To understand the structure of the modeled configuration, we use the field
line mapping technique by generalizing it to spherical geometry. It is
demonstrated that the initial potential configuration contains a hyperbolic
flux tube (HFT) which is a union of two intersecting quasi-separatrix layers.
This HFT provides a partition of the closed magnetic flux between the AR and
the global solar magnetic field. The vortex motions applied to the AR interlock
the field lines in the coronal volume to form additionally two new HFTs pinched
into thin current layers. Reconnection in these current layers helps to
redistribute the magnetic flux and current within the AR in the
flux-cancellation phase. In this phase, a magnetic flux rope is formed together
with a bald patch separatrix surface wrapping around the rope. Other important
implications of the identified structural features of the modeled configuration
are also discussed.Comment: 25 pages, 11 figures, to appear in ApJ 200
Tactical diagrammatic reasoning
Although automated reasoning with diagrams has been possible for some years,
tools for diagrammatic reasoning are generally much less sophisticated than
their sentential cousins. The tasks of exploring levels of automation and
abstraction in the construction of proofs and of providing explanations of
solutions expressed in the proofs remain to be addressed. In this paper we take
an interactive proof assistant for Euler diagrams, Speedith, and add tactics to
its reasoning engine, providing a level of automation in the construction of
proofs. By adding tactics to Speedith's repertoire of inferences, we ease the
interaction between the user and the system and capture a higher level
explanation of the essence of the proof. We analysed the design options for
tactics by using metrics which relate to human readability, such as the number
of inferences and the amount of clutter present in diagrams. Thus, in contrast
to the normal case with sentential tactics, our tactics are designed to not
only prove the theorem, but also to support explanation
Slow Rise and Partial Eruption of a Double-Decker Filament. I Observations and Interpretation
We study an active-region dextral filament which was composed of two branches
separated in height by about 13 Mm. This "double-decker" configuration
sustained for days before the upper branch erupted with a GOES-class M1.0 flare
on 2010 August 7. Analyzing this evolution, we obtain the following main
results. 1) During hours before the eruption, filament threads within the lower
branch were observed to intermittently brighten up, lift upward, and then merge
with the upper branch. The merging process contributed magnetic flux and
current to the upper branch, resulting in its quasi-static ascent. 2) This
transfer might serve as the key mechanism for the upper branch to lose
equilibrium by reaching the limiting flux that can be stably held down by the
overlying field or by reaching the threshold of the torus instability. 3) The
erupting branch first straightened from a reverse S shape that followed the
polarity inversion line and then writhed into a forward S shape. This shows a
transfer of left-handed helicity in a sequence of writhe-twist-writhe. The fact
that the initial writhe is converted into the twist of the flux rope excludes
the helical kink instability as the trigger process of the eruption, but
supports the occurrence of the instability in the main phase, which is indeed
indicated by the very strong writhing motion. 4) A hard X-ray sigmoid, likely
of coronal origin, formed in the gap between the two original filament branches
in the impulsive phase of the associated flare. This supports a model of
transient sigmoids forming in the vertical flare current sheet. 5) Left-handed
magnetic helicity is inferred for both branches of the dextral filament. 6) Two
types of force-free magnetic configurations are compatible with the data, a
double flux rope equilibrium and a single flux rope situated above a loop
arcade
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