Proton-Coupled Electron Flow in Protein Redox Machines

Electron transfer (ET) reactions are fundamental steps in biological redox processes. Respiration is a case in point: at least 15 ET reactions are required to take reducing equivalents from NADH, deposit them in O_2, and generate the electrochemical proton gradient that drives ATP synthesis. Most of these reactions involve quantum tunneling between weakly coupled redox cofactors (ET distances > 10 Å) embedded in the interiors of folded proteins. Here we review experimental findings that have shed light on the factors controlling these distant ET events. We also review work on a sensitizer-modified copper protein photosystem in which multistep electron tunneling (hopping) through an intervening tryptophan is orders of magnitude faster than the corresponding single-step ET reaction.If proton transfers are coupled to ET events, we refer to the processes as proton coupled ET, or PCET, a term introduced by Huynh and Meyer in 1981. Here we focus on two protein redox machines, photosystem II and ribonucleotide reductase, where PCET processes involving tyrosines are believed to be critical for function. Relevant tyrosine model systems also will be discussed

Mechanism of H_2 Evolution from a Photogenerated Hydridocobaloxime

Proton transfer from the triplet excited state of brominated naphthol to a difluoroboryl bridged Co^I-diglyoxime complex, forming Co^(III)H, was monitored via transient absorption. The second-order rate constant for Co^(III)H formation is in the range (3.5−4.7) × 10^9 M^(−1) s^(−1), with proton transfer coupled to excited-state deactivation of the photoacid. Co^(III)H is subsequently reduced by excess Co^I-diglyoxime in solution to produce Co^(II)H (k_(red) = 9.2 × 10^6 M^(−1) s^(−1)), which is then protonated to yield Co^(II)-diglyoxime and H_2

Human Response to Aircraft-Noise-Induced Building Vibration

The effects of noise induced building structure vibration and the rattle of objects on human response to aircraft flyover noise were investigated in a series of studies conducted in both the field and the laboratory. The subjective detection thresholds for vibration and rattle were determined as well as the effect of vibration and rattle upon aircraft noise annoyance

A Proposed Military Construction Facility Investment Model

The fiscal year (FY) 1999 and FY2000 National Defense Authorization Acts (NDAA) amended Title 10 USC, Section 17, and directed the secretary of defense to report annually on the capability of installations and facilities to provide support to forces in the conduct of their missions. This has come to be known as the Installations\u27 Readiness Report (IRR). The Air Force\u27s IRR links facility sustainment, restoration, and modernization (SRM) requirements, with the impact on the installation\u27s ability to support the mission associated with the particular facility class. The Air Force\u27s centralized military construction (MILCON) program model used to program major facility requirements does not directly target facility investment in the deficient facility classes defined in the Installations\u27 Readiness Report. This research combined the system dynamics and value-focused thinking methodologies together to develop a proposed MILCON model that might better target funding of deficient facility class requirements. The results from a system dynamics analysis of the existing MILCON model were used to better understand the MILCON program and leverage management policies in a proposed MILCON model. The proposed MILCON model was then developed using a gold standard value-focused thinking approach. The Air Force\u27s goals and objectives for the MILCON program were derived from a literature review of key doctrine, policies, and guidance. The proposed model was also evaluated to identify relevant favorable or unfavorable behavior trends in eliminating deficient facility class requirements. The proposed model provides a significant short and long-term improvement over the existing model in targeting and eliminating deficient facility class requirements. The model demonstrates a 20 percent improvement in targeting these facility requirements in FY2004 and a long-term trend towards completely eliminating these requirements

RS CVn binaries: Testing the solar-stellar dynamo connection

We have used the Extreme Ultraviolet Explorer satellite to study the coronal emission from the EUV-bright RS CVn binaries Sigma2 CrB, observed February 10-21, 1994, and II Peg, observed October 1-5, 1993. We present time-resolved and integrated EUV short-, medium-, and long-wavelength spectra for these binaries. Sigma2 CrB shows significant first-order emission features in the long-wavelength region. The coronal emission distributions and electron densities are estimated for those active coronae dominated by high temperature plasma

An Analysis of Ground Stone from the Basketmaker Communities Project in Montezuma County, Southwest Colorado

In this thesis, I analyze an assemblage of ground stone tools, including manos and metates, from Basketmaker III period (A.D. 500-725) settlements in the central Mesa Verde region of Montezuma County, Colorado. Ground stone is a historically understudied class of artifacts, and the data collection and analysis practices employed for most projects remain subpar, despite the publication of best practices guidelines (Adams 2014). Ground stone informs on critical research topics and must be analyzed to the same degree as other artifact categories. The sites include the Dillard site (5MT10647), an aggregated site with a great kiva, and five surrounding, smaller habitation sites termed hamlets. The Basketmaker Communities Project, conducted by The Crow Canyon Archaeological Center, synthesized comparable data from contemporary sites in the region, asking questions about social dynamics at the earliest period of agricultural, sedentary lifeways in this region. Through the ground stone analysis, I gain insight to the production, use, maintenance and discard of ground stone tools and use the differences and similarities between the Dillard site and the hamlets to discern social dynamics at sites of different scales at the period when lifeways were drastically changing for Ancestral Pueblo people in the central Mesa Verde region. The results show that residents of the Dillard site ground in longer, intensive sessions, as indicated by their preference for formal tools and their investment in the use lives of those tools. While individual households ground some of their own product, not every household contained grinding tools. Combined with the presence of a mealing pit room that is closely associated with the great kiva, this indicates that at least some grinding took place above the household level at the Dillard site. Ground stone tools from the hamlets were less formal than those at the Dillard site, and while less comfortable in long grinding sessions, required less time to manufacture and maintain. Because of the smaller population at the hamlet sites, grinding tasks had to be completed in shorter sessions to allow time for other household tasks. The higher grinding efficiency of tools at the hamlets reflect the need to maximize ground product processed in each session. Advisor: Carrie C. Heitma

An Analysis of Ground Stone from the Basketmaker Communities Project in Montezuma County, Southwest Colorado

In this thesis, I analyze an assemblage of ground stone tools, including manos and metates, from Basketmaker III period (A.D. 500-725) settlements in the central Mesa Verde region of Montezuma County, Colorado. Ground stone is a historically understudied class of artifacts, and the data collection and analysis practices employed for most projects remain subpar, despite the publication of best practices guidelines (Adams 2014). Ground stone informs on critical research topics and must be analyzed to the same degree as other artifact categories. The sites include the Dillard site (5MT10647), an aggregated site with a great kiva, and five surrounding, smaller habitation sites termed hamlets. The Basketmaker Communities Project, conducted by The Crow Canyon Archaeological Center, synthesized comparable data from contemporary sites in the region, asking questions about social dynamics at the earliest period of agricultural, sedentary lifeways in this region. Through the ground stone analysis, I gain insight to the production, use, maintenance and discard of ground stone tools and use the differences and similarities between the Dillard site and the hamlets to discern social dynamics at sites of different scales at the period when lifeways were drastically changing for Ancestral Pueblo people in the central Mesa Verde region. The results show that residents of the Dillard site ground in longer, intensive sessions, as indicated by their preference for formal tools and their investment in the use lives of those tools. While individual households ground some of their own product, not every household contained grinding tools. Combined with the presence of a mealing pit room that is closely associated with the great kiva, this indicates that at least some grinding took place above the household level at the Dillard site. Ground stone tools from the hamlets were less formal than those at the Dillard site, and while less comfortable in long grinding sessions, required less time to manufacture and maintain. Because of the smaller population at the hamlet sites, grinding tasks had to be completed in shorter sessions to allow time for other household tasks. The higher grinding efficiency of tools at the hamlets reflect the need to maximize ground product processed in each session. Advisor: Carrie C. Heitma