Matching Items (48)
Description
While exercising mammalian muscle increasingly relies on carbohydrates for fuel as aerobic exercise intensity rises above the moderate range, flying birds are extraordinary endurance athletes and fuel flight, a moderate-high intensity exercise, almost exclusively with lipid. In addition, Aves have long lifespans compared to weight-matched mammals. As skeletal muscle mitochondria account for the majority of oxygen consumption during aerobic exercise, the primary goal was to investigate differences in isolated muscle mitochondria between these species and to examine to what extent factors intrinsic to mitochondria may account for the behavior observed in the intact tissue and whole organism. First, maximal enzyme activities were assessed in sparrow and rat mitochondria. Citrate synthase and aspartate aminotransferase activity were higher in sparrow compared to rat mitochondria, while glutamate dehydrogenase activity was lower. Sparrow mitochondrial NAD-linked isocitrate dehydrogenase activity was dependent on phosphate, unlike the mammalian enzyme. Next, the rate of oxygen consumption (JO), electron transport chain (ETC) activity, and reactive oxygen species (ROS) production were assessed in intact mitochondria. Maximal rates of fat oxidation were lower than for carbohydrate in rat but not sparrow mitochondria. ETC activity was higher in sparrows, but no differences were found in ROS production between species. Finally, fuel selection and control of respiration at three rates between rest and maximum were assessed. Mitochondrial fuel oxidation and selection mirrored that of the whole body; in rat mitochondria the reliance on carbohydrate increased as the rate of oxygen consumption increased, whereas fat dominated under all conditions in the sparrow. These data indicate fuel selection, at least in part, can be modulated at the level of the mitochondrial matrix when multiple substrates are present at saturating levels. As an increase in matrix oxidation-reduction potential has been linked to a suppression of fat oxidation and high ROS production, the high ETC activity relative to dehydrogenase activity in avian compared to mammalian mitochondria may result in lower matrix oxidation-reduction potential, allowing fatty acid oxidation to proceed while also resulting in low ROS production in vivo.
ContributorsKuzmiak, Sarah (Author) / Willis, Wayne T (Thesis advisor) / Mandarino, Lawrence (Committee member) / Sweazea, Karen (Committee member) / Harrison, Jon (Committee member) / Gadau, Juergen (Committee member) / Arizona State University (Publisher)
Created2012
Description
This thesis deals with the first measurements done with a cold neutron beam at the Spallation Neutron Source at Oak Ridge National Laboratory. The experimental technique consisted of capturing polarized cold neutrons by nuclei to measure parity-violation in the angular distribution of the gamma rays following neutron capture. The measurements presented here for the nuclei Chlorine ( 35Cl) and Aluminum ( 27Al ) are part of a program with the ultimate goal of measuring the asymmetry in the angular distribution of gamma rays emitted in the capture of neutrons on protons, with a precision better than 10-8, in order to extract the weak hadronic coupling constant due to pion exchange interaction with isospin change equal with one ( hπ 1). Based on theoretical calculations asymmetry in the angular distribution of the gamma rays from neutron capture on protons has an estimated size of 5·10-8. This implies that the Al parity violation asymmetry and its uncertainty have to be known with a precision smaller than 4·10-8. The proton target is liquid Hydrogen (H2) contained in an Aluminum vessel. Results are presented for parity violation and parity-conserving asymmetries in Chlorine and Aluminum. The systematic and statistical uncertainties in the calculation of the parity-violating and parity-conserving asymmetries are discussed.
ContributorsBalascuta, Septimiu (Author) / Alarcon, Ricardo (Thesis advisor) / Belitsky, Andrei (Committee member) / Doak, Bruce (Committee member) / Comfort, Joseph (Committee member) / Schmidt, Kevin (Committee member) / Arizona State University (Publisher)
Created2012
Description
Here I present a phylogeographic study of at least six reproductively isolated lineages of harvester ants within the Pogonomyrmex barbatus and P. rugosus species group. The genetic and geographic relationships within this clade are complex: four of the identified lineages are divided into two pairs, and each pair has evolved under a mutualistic system that necessitates sympatry. These paired lineages are dependent upon one another because interlineage matings within each pair are the sole source of hybrid F1 workers; these workers build and sustain the colonies, facilitating the production of the reproductive caste, which results solely from intralineage fertilizations. This system of genetic caste determination (GCD) maintains genetic isolation among these closely related lineages, while simultaneously requiring co-expansion and emigration as their distributions have changed over time. Previous studies have also demonstrated that three of the four lineages displaying this unique genetic caste determination phenotype are of hybrid origin. Thus, reconstructing the phylogenetic and geographic history of this group allows us to evaluate past insights and plan future inquiries in a more complete historical biogeographic context. Using mitochondrial DNA sequences sampled across most of the morphospecies' ranges in the U.S. and Mexico, I employed several methods of phylogenetic and DNA sequence analysis, along with comparisons to geological, biogeographic, and phylogeographic studies throughout the sampled regions. These analyses on Pogonomyrmex harvester ants reveal a complex pattern of vicariance and dispersal that is largely concordant with models of late Miocene, Pliocene, and Pleistocene range shifts among various arid-adapted taxa in North America.
ContributorsMott, Brendon (Author) / Gadau, Juergen (Thesis advisor) / Fewell, Jennifer (Committee member) / Anderson, Kirk (Committee member) / Arizona State University (Publisher)
Created2012
Description
In social insect colonies, as with individual animals, the rates of biological processes scale with body size. The remarkable explanatory power of metabolic allometry in ecology and evolutionary biology derives from the great diversity of life exhibiting a nonlinear scaling pattern in which metabolic rates are not proportional to mass, but rather exhibit a hypometric relationship with body size. While one theory suggests that the supply of energy is a major physiological constraint, an alternative theory is that the demand for energy is regulated by behavior. The central hypothesis of this dissertation research is that increases in colony size reduce the proportion of individuals actively engaged in colony labor with consequences for energetic scaling at the whole-colony level of biological organization. A combination of methods from comparative physiology and animal behavior were developed to investigate scaling relationships in laboratory-reared colonies of the seed-harvester ant, Pogonomyrmex californicus. To determine metabolic rates, flow-through respirometry made it possible to directly measure the carbon dioxide production and oxygen consumption of whole colonies. By recording video of colony behavior, for which ants were individually paint-marked for identification, it was possible to reconstruct the communication networks through which information is transmitted throughout the colony. Whole colonies of P. californicus were found to exhibit a robust hypometric allometry in which mass-specific metabolic rates decrease with increasing colony size. The distribution of walking speeds also scaled with colony size so that larger colonies were composed of relatively more inactive ants than smaller colonies. If colonies were broken into random collections of workers, metabolic rates scaled isometrically, but when entire colonies were reduced in size while retaining functionality (queens, juveniles, workers), they continued to exhibit a metabolic hypometry. The communication networks in P. californicus colonies contain a high frequency of feed-forward interaction patterns consistent with those of complex regulatory systems. Furthermore, the scaling of these communication pathways with size is a plausible mechanism for the regulation of whole-colony metabolic scaling. The continued development of a network theory approach to integrating behavior and metabolism will reveal insights into the evolution of collective animal behavior, ecological dynamics, and social cohesion.
ContributorsWaters, James S., 1983- (Author) / Harrison, Jon F. (Thesis advisor) / Quinlan, Michael C. (Committee member) / Pratt, Stephen C. (Committee member) / Fewell, Jennifer H. (Committee member) / Gadau, Juergen (Committee member) / Arizona State University (Publisher)
Created2012
Description
Cuticular hydrocarbons (CHCs) play a crucial role in social insect recognition systems. In this study we investigated mate choice in the red harvester ant, Pogonomyrmex barbatus. In Phoenix, this species has two lineages, J1 and J2, which look identical, but are genetically isolated. In the genetic caste determination (GCD) system workers and queens are determined by their genotype (i.e., workers develop from interlineage crosses, queens from intralineage crosses). As such, J1 and J2 lineages are dependent on each other in order for colonies to produce both workers and reproductive queens. Given their genetic isolation and interdependence, we hypothesized that the CHCs of alate males and queens are affected by lineage, and that differences in the CHC profile are used for mate recognition. We tested these hypotheses by analyzing the lineage distributions of actively mating pairs (n=65), and compared them with the overall distribution of male and female sexuals (n=180). We additionally analyzed the five most abundant CHC compounds for 20 of the actively mating P. barbatus alate male and queen pairs to determine how variable the two lineages are between each sex. We found that mating pair distributions did not significantly differ from those expected under a random mating system (�2= 1.4349, P= 0.6973), however, CHC profiles did differ between J1 and J2 lineages and sexes for the five most abundant CHC compounds. Our results show that random mating is taking place in this population, however given the differences observed in CHC profiles, mate recognition could be taking place.
ContributorsTula Del Moral Testai, Pedro Rafael (Co-author) / Cash, Elizabeth (Co-author) / Gadau, Juergen (Thesis director) / Liebig, Juergen (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / School of Life Sciences (Contributor)
Created2014-05
Description
I tested the hypothesis that in mature colonies of the seed harvester Pogonomyrmex californicus ant species, paired pleometrotic queens would produce workers more efficiently after a massive removal of their work force than haplometrotic queens, paired pleometrotic with haplometrotic queens, and single pleometrotic queens. I suggested that the paired pleometrotic queens would have an advantage of cooperating together in reproducing more workers quicker than the other conditions to make up for the lost workers. This would demonstrate a benefit that pleometrosis has over haplometrosis for mature colonies, which would explain why pleometrosis continues for P.californicus after colony foundation. After removing all but twenty workers for every colony, I took pictures and counted the emerging brood for 52 days. Analyses showed that the paired pleometrotic queens and the haplometrotic queens both grew at an equally efficient rate and the paired pleometrotic and haplometrotic queens growing the least efficiently. However, the results were not significant and did not support the hypothesis that paired pleometrotic queens recover from worker loss more proficiently than other social systems.
ContributorsFernandez, Marisa Raquel (Author) / Fewell, Jennifer (Thesis director) / Gadau, Juergen (Committee member) / Haney, Brian (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / Department of Psychology (Contributor)
Created2014-05
Description
Wolbachia is a genus of obligately intracellular bacterial endosymbionts of arthropods and nematodes, infecting up to 66% of all such species. In order to ensure its transmission, it may modify host reproduction by inducing one of four phenotypes: cytoplasmic incompatibility, feminization of genetic males, killing of male embryos, and induction of thelytokous parthenogenesis. This investigation was a characterization of the so-far unexamined Wolbachia infection of Pogonomyrmex ants. Five main questions were addressed: whether Wolbachia infection rates vary between North and South America, whether infection rates are dependent on host range, whether Wolbachia affects the caste determination of P. barbatus, whether infection rates in Pogonomyrmex are similar to those of other ants, and whether Wolbachia phylogeny parallels the phylogeny of its Pogonomyrmex hosts. Using PCR amplification of the wsp, ftsZ, and gatB loci, Wolbachia infections were detected in four of fifteen Pogonomyrmex species (26.7%), providing the first known evidence of Wolbachia infection in this genus. All infected species were from South America, specifically Argentina. Therefore, Wolbachia has no role in the caste determination of the North American species P. barbatus. Additionally, while it appears that the incidence of Wolbachia in Pogonomyrmex may be limited to South America, host range did not correlate with infection status. The incidence of Wolbachia in Pogonomyrmex as a whole was similar to that of invasive Solenopsis and Linepithema species, but not to Wasmannia auropunctata or Anoplolepis gracilipes, which retain Wolbachia infection in non-native locations. This suggests that there may be a parallel in Wolbachia infection spread in certain short-term models of species colonization and long-term models of genus radiation. Finally, there was no congruity between host and parasite phylogeny according to maximum likelihood analyses, necessarily due to horizontal transfer of Wolbachia between hosts and lateral gene transfer between Wolbachia strains within hosts.
ContributorsHarris, Alexandre Marm (Author) / Gadau, Juergen (Thesis director) / Martin, Thomas (Committee member) / Helmkampf, Martin Erik (Committee member) / Barrett, The Honors College (Contributor) / Computer Science and Engineering Program (Contributor) / School of Life Sciences (Contributor)
Created2014-05
Description
As the world energy demand increases, semiconductor devices with high energy conversion efficiency become more and more desirable. The energy conversion consists of two distinct processes, namely energy generation and usage. In this dissertation, novel multi-junction solar cells and light emitting diodes (LEDs) are proposed and studied for high energy conversion efficiency in both processes, respectively. The first half of this dissertation discusses the practically achievable energy conversion efficiency limit of solar cells. Since the demonstration of the Si solar cell in 1954, the performance of solar cells has been improved tremendously and recently reached 41.6% energy conversion efficiency. However, it seems rather challenging to further increase the solar cell efficiency. The state-of-the-art triple junction solar cells are analyzed to help understand the limiting factors. To address these issues, the monolithically integrated II-VI and III-V material system is proposed for solar cell applications. This material system covers the entire solar spectrum with a continuous selection of energy bandgaps and can be grown lattice matched on a GaSb substrate. Moreover, six four-junction solar cells are designed for AM0 and AM1.5D solar spectra based on this material system, and new design rules are proposed. The achievable conversion efficiencies for these designs are calculated using the commercial software package Silvaco with real material parameters. The second half of this dissertation studies the semiconductor luminescence refrigeration, which corresponds to over 100% energy usage efficiency. Although cooling has been realized in rare-earth doped glass by laser pumping, semiconductor based cooling is yet to be realized. In this work, a device structure that monolithically integrates a GaAs hemisphere with an InGaAs/GaAs quantum-well thin slab LED is proposed to realize cooling in semiconductor. The device electrical and optical performance is calculated. The proposed device then is fabricated using nine times photolithography and eight masks. The critical process steps, such as photoresist reflow and dry etch, are simulated to insure successful processing. Optical testing is done with the devices at various laser injection levels and the internal quantum efficiency, external quantum efficiency and extraction efficiency are measured.
ContributorsWu, Songnan (Author) / Zhang, Yong-Hang (Thesis advisor) / Menéndez, Jose (Committee member) / Ponce, Fernando (Committee member) / Belitsky, Andrei (Committee member) / Schroder, Dieter (Committee member) / Arizona State University (Publisher)
Created2010
Description
The first numerical predictions of the dynamical diquark model of multiquark exotic hadrons are presented. Using Born-Oppenheimer potentials calculated from lattice QCD and phenomenological diquark(triquark) masses, mass eigenvalues that are degenerate in spin and isospin are computed from numerical solutions to both coupled and uncoupled Schroedinger equations. Assuming reasonable estimates of the fine-structure splittings, we find that the band structure of our mass spectra agrees well with the experimentally observed spectrum of charmonium-like states. Using our best fits, we predict a number of unobserved states, such as pentaquark states that lie below the charmonium-plus-nucleon threshold.
ContributorsPeterson, Curtis Taylor Taylor (Author) / Lebed, Richard (Thesis director) / Belitsky, Andrei (Committee member) / Department of Physics (Contributor, Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
This thesis focuses on how domain formation and local disorder mediate non-equilibrium order in the context of condensed matter physics. More specifically, the data supports c-axis CDW ordering in the context of the rare-earth Tritellurides. Experimental studies were performed on Pd:ErTe3 by ultra-fast pump-probe and x-ray free electron laser (XFEL). Ginzburg Landau models were used to simulate domain formation. Universal scaling analysis on the data reveals that topological defects govern the relaxation of domain walls in Pd:ErTe3. This thesis presents information on progress towards using light to control material domains.
ContributorsMiller, Alex (Author) / Teitelbaum, Samuel (Thesis director) / Belitsky, Andrei (Committee member) / Kaindl, Robert (Committee member) / Barrett, The Honors College (Contributor) / Department of Physics (Contributor) / School of Mathematical and Statistical Sciences (Contributor)
Created2023-05