Farming for ecosystem services: A case study of multifunctional agriculture in Iowa, U.S.A

Agriculture in the United States faces major challenges for the 21st Century; it is at a pivotal stage in terms of integrating societal demands for sustainability and enhanced quality of life from agricultural lands. A growing understanding that farms play key roles in provisioning a wide range of ecosystem services is converging with a surge in public interest in the sustainability of farming and food systems. Farmers in the US Corn Belt are being solicited to manage for an increasingly complex and expanding suite of production and environmental benefits. However, managing landscapes for multiple objectives presents a major challenge and inherently increases management complexity. A critical challenge lies in defining an appropriate set of agriculture and environmental objectives for management across spatial scales. The goal of this research was to analyze the degree to which there is a capacity to manage agricultural landscapes for multiple ecosystem services with existing and emerging agricultural management practices. I addressed this goal by conducting a case study with stakeholders representing agricultural and environmental interests in Iowa, U.S.A., through a mixed methods approach utilizing the Delphi survey technique and in-person interviews with photo elicitation. This thesis presents the case study results regarding the relationship between ecosystem services and agricultural land management; identifies farm scale management practices that are most promising for achieving ecosystem service objectives across scales; and, additionally, presents a portfolio of landscape visualizations depicting scenarios of land management alternatives

Two-body effects in the decay rate of atomic levels

Recoil corrections to the atomic decay rate are considered in the order of Zm/M . The expressions are treated exactly without any expansion over Z alpha. The expressions obtained are valid both for muonic atoms (for which they contribute on the level of a few percent in high Z ions) and for electronic atoms. Explicit results for Lyman-alpha transitions for low-Z of the order (Zm/M)(Z alpha)^2 are also presented.Comment: 5 pages, 1 table, email: [email protected]

Infrared Observations During the Secondary Eclipse of HD 209458 b II. Strong Limits on the Infrared Spectrum Near 2.2 Microns

We report observations of the transiting extrasolar planet, HD 209458 b, designed to detect the secondary eclipse. We employ the method of `occultation spectroscopy', which searches in combined light (star and planet) for the disappearance and reappearance of weak infrared spectral features due to the planet as it passes behind the star and reappears. Our observations cover two predicted secondary eclipse events, and we obtained 1036 individual spectra of the HD 209458 system using the SpeX instrument at the NASA IRTF in September 2001. Our spectra extend from 1.9 to 4.2 microns with a spectral resolution of 1500. We have searched for a continuum peak near 2.2 microns (caused by CO and water absorption bands), as predicted by some models of the planetary atmosphere to be approximately 6E-4 of the stellar flux, but no such peak is detected at a level of about 3E-4 of the stellar flux. Our results represent the strongest limits on the infrared spectrum of the planet to date and carry significant implications for understanding the planetary atmosphere. In particular, some models that assume the stellar irradiation is re-radiated entirely on the sub-stellar hemisphere predict a flux peak inconsistent with our observations. Several physical mechanisms can improve agreement with our observations, including the re-distribution of heat by global circulation, a nearly isothermal atmosphere, and/or the presence of a high cloud.Comment: Accepted to the Astrophysical Journal 17 pages, 6 figure

Preliminary results of the Mariner IV radio occultation measurements of the upper atmosphere of Mars

Mariner IV radio occultation measurements of Mars upper atmospher

Preliminary results of the Mariner IV OCCULATION measurement of the atmosphere of Mars

Mariner IV radio occultation measurement of Mars atmospher

Interacting supernovae and supernova impostors. LSQ13zm: an outburst heralds the death of a massive star

We report photometric and spectroscopic observations of the optical transient LSQ13zm. Historical data reveal the presence of an eruptive episode (that we label as ‘2013a’) followed by a much brighter outburst (‘2013b’) three weeks later, that we argue to be the genuine supernova explosion. This sequence of events closely resemble those observed for SN 2010mc and (in 2012) SN 2009ip. The absolute magnitude reached by LSQ13zm during 2013a (M_R=−14.87±0.25mag) is comparable with those of supernova impostors, while that of the 2013b event (M_R=−18.46±0.21mag) is consistent with those of interacting supernovae. Our spectra reveal the presence of a dense and structured circumstellar medium, probably produced through numerous pre-supernova mass-loss events. In addition, we find evidence for high-velocity ejecta, with a fraction of gas expelled at more than 20000 km s^(−1). The spectra of LSQ13zm show remarkable similarity with those of well-studied core-collapse supernovae. From the analysis of the available photometric and spectroscopic data, we conclude that we first observed the last event of an eruptive sequence from a massive star, likely a Luminous Blue Variable, which a short time later exploded as a core-collapse supernova. The detailed analysis of archival images suggest that the host galaxy is a star-forming Blue Dwarf Compact Galaxy