3,908 research outputs found
Nuclear and Particle Astrophysics at CIPANP 2003
In the nuclear and particle astrophysics session of CIPANP 2003 we heard
talks on a number of topics, focused for the most part into four broad areas.
Here we outline the discussions of the standard cosmological model, dark matter
searches, cosmic rays, and neutrino astrophysics. The robustness of theoretical
and experimental programs in all of these areas is very encouraging, and we
expect to have many questions answered, and new ones asked, in time for CIPANP
2006.Comment: 5 pages, uses aipproc.cls, parallel session summary to appear in
proceedings of CIPANP 200
Optimal Design of Government Hierarchy for Ecosystem Service Provision
There is broad concern that humans are transforming our environment. This transformation has potential to impact humanity as we depend on the environment ecosystem services. According to the Millennium Assessment (2005), degradation and unsustainable exploitation presently threaten over 60% of ecosystem services with real implications for health and standards of living. Furthermore, both the exploitation of ecosystem services and the growth rate of that exploitation have been far higher in recent decades than ever before due to population growth and rising standards of living, i.e. consumption. Increasing pressure on ecosystem services has driven thinking on mitigation strategies. Payment for ecosystem services (PES) has emerged as a strategy to encourage provision of services or, often, to discourage activities that reduce provision. In economic terms, the inability of agents to capture the full rents of service provision results in divergent private and social values. By creating markets for these services, PES arrangements can correct this disincentive and bring provision closer to the socially optimal level. While private sector PES schemes have been envisioned and in some cases implemented, most large-scale PES programs to date have been implemented by governments. We consider optimal design of policy aimed at increasing the provision of services from private land. In particular, we examine on a theoretical level the possibility of optimal decision-making hierarchies among government agencies targeting ecosystem service provision. Should we have multiple agencies focusing on separate services or one agency coordinating efforts across services? Should policy be implemented nationally, regionally, or locally? Under what conditions and assumptions does one organizational structure stand out as optimal? To answer these questions, we adapt the model of hierarchy design developed by Hart and Moore (JPE, 2005). We develop a two period model of decision-making with n agencies and m assets. The assets are parcels available for targeting under PES schemes. Each agency is tasked with thinking about how to use a subset of the m assets to enhance service provision, according to its mission. Also associated with each agency is some probability of success in its task - i.e., the probability of thinking of a productive use for the assigned subset of assets - and a value generated for society if the task is completed. There is some rivality among assets; the use of an asset by one agency may preclude its use by another. Determination of seniority and assignment of tasks occur in period 0. In period 1, agencies with access to all assets they require carry out the tasks and generate value for society. Assets are unavailable if put to a conflicting use by a senior agency. Altering the hierarchy structure alters the set of completed tasks and thus the total value. We optimize across hierarchies by assigning tasks and seniority in period 0 to maximize total expected value in period 1. Following the development of the model, we explore implications and results. To demonstrate the driving intuition, we provide results in the two-agency, three-agency, and general case. Our results shed light on the optimal design of hierarchies, including the optimal relationship between coordinators (those considering how to use many assets simultaneously) and specialists (those considering a narrower subset of assets). The model relies on a number of assumptions - some of which are more restrictive than others - and we examine the implications for our results of relaxing assumptions. Two preliminary results stand out as generally applicable. First, in an optimal hierarchy an agency's seniority should be inversely related to its probability of success. So agencies with a low probability of having an idea about how to use the assets assigned to them should have high seniority. This seems counter-intuitive as the value of an idea is not considered, but it becomes clearer considering that tasks and seniority are assigned in period 0 to maximize period 1 total expected value. With this endogenized task selection, no agency would be assigned a task with low value and a low probability of success. Second, crisscross hierarchies are never optimal. This result, which states that agency a should never be senior to agency b on one asset and junior on another, is more intuitive. The central contribution of this paper is the adaptation of a theoretical model of hierarchy design to the context of programs targeting ecosystem services. The nature of interaction between various government entities involved in encouraging service provision necessitated an alternative representation of rivality between agencies. Assumptions were evaluated and revised based on their applicability to behavior in this context. Future research may involve further modification of the model to account for issues like threshold effects, joint production, and uncertainty.Environmental Economics and Policy,
Research relative to the heavy isotope spectrometer telescope experiment
The Heavy Isotope Spectrometer Telescope (HIST) was launched during August 1978 on ISEE-3 (ICE). HIST was designed to measure the isotopic composition of solar, galactic, and interplanetary cosmic ray nuclei for the elements from H to Ni (1 less than or equal to Z less than or equal to 28) in the energy range from approximately 5 to approximately 200 MeV/nucleon. The results of these measurements have been used in studies of the composition of solar matter and galactic cosmic ray sources, the study of nucleosynthesis processes, studies of particle acceleration and propagation, and studies of the life-history of cosmic rays in the heliosphere and in the galaxy. On December 1, 1978, after 110 days in orbit, HIST suffered an electronic failure in its readout system. After that point, only one-half of the telemetry bits associated with the pulse heights measured by HIST were transmitted to Earth. As a result, the resolution of HIST was significantly degraded, and it served as an element rather than an isotope spectrometer. Fortunately, HIST was able to measure the isotopic composition of heavy nuclei in the 9/23/78 solar event (the largest solar energetic particle event since 1972) during the brief period that it operated at full resolution. This grant funded the analysis of data from the HIST instrument over the period from 12/1/85 to 11/30/92. In section 2 of this final report, we summarize the scientific accomplishments that have resulted from HIST measurements during this time period. A bibliography of tasks and papers that resulted is attached
Our heliosphere: The new view from Voyager
Launched in 1977 on a journey to the giant outer planets and beyond, Voyager 1 and 2 have explored the spatial and dynamical properties of the heliosphere that modulates the inward flow of galactic cosmic rays and is the source of anomalous cosmic rays. The two spacecraft are in the heliosheath beyond the termination shock where the supersonic solar wind has slowed as it approaches the boundary of the heliosphere. The shock crossing was 10 AU closer at Voyager 2 in the south than at Voyager 1 in the north, indicating a local interstellar magnetic field pressing inward more strongly on the southern hemisphere. The expected source of anomalous cosmic rays was not observed at the shock, and their intensity has increased deeper in the heliosheath, indicating the source is elsewhere on the shock or in the heliosheath. Voyager 1, now at 121 AU at 35 degrees north, has been in a quasi-stagnation region since 2010 where there is no outward motion of the wind, the magnetic field is enhanced, and the galactic cosmic ray intensity is increasing. In contrast, the heliosheath flow at Voyager 2 at 99 AU and 30 degrees south is faster and increasingly deflected in a non-radial direction as it turns to flow tailward. These observations will be placed in the context of current models of the interaction of the solar and interstellar winds
Voyager 1 in the Vicinity of the Termination Shock: an Overview of Observations beyond 94 AU in the Heliosheath
Voyager 1 has crossed the termination shock, a major milestone in its journey to interstellar space. Since
mid-2002, Voyager 1 has been moving outward with the shock, which reached its maximum distance in
mid-2004 and starting moving back in as the solar wind pressure declined. On December 15, 2004, the
intensity of low energy ions increased rapidly as the termination shock approached Voyager, and plasma
waves excited by electrons streaming along the magnetic field indicated the shock was nearby. Voyager 1
crossed the inward moving shock on December 16 at 94 AU, observing the enhanced magnetic field as
expected in the subsonic flow in the heliosheath. The lowest energy particles also abruptly increased with a
low energy spectral slope of approximately -1.5, corresponding to a shock strength of ~2.5. In distinction to
the upstream ions which were highly variable and strongly beamed along the magnetic field, in the
heliosheath the energetic ion intensity is much less variable and more nearly isotropic, indicating a stable
shock source and steady conditions for diffusive propagation. However, the low energy anomalous cosmic
rays were not observed at the shock, indicating that their source region is remote from the location of
Voyager 1. Continuing observations should reveal new aspects of this final frontier of the heliosphere
Methods by which one hundred twenty men of Bazine and Highpoint townships of Ness County, Kansas became established in farming
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Two Voyagers to Saturn - How Voyager 2 has been reprogrammed
In the past two years, the Pioneer 11 and the Voyager 1 encounters with
Saturn have revealed a remarkable richness
and diversity of physical phenomena.
As a result of these discoveries and of
continued Earth-based studies, major
changes have been made in the observations
planned for Voyager 2, providing
additional opportunities for discovery and
understanding of the Saturn system.
These opportunities are further enhanced
by the significantly different path that
Voyager 2 must take through the system,
passing 101,000 km above Saturn's cloud
tops on 26 August as it continues on to
Uranus. Of necessity, the most exciting
discovery will be unexpected; but some of
the opportunities for new observations are
described below for each of the four major
areas of investigation-the atmosphere,
rings, satellites and magnetosphere
Appearance of a Third Episode of Enhanced Particle Intensities at 94 AU: Voyager 1 in the Heliosheath
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