Study of the general mechanism of stress corrosion of aluminum alloys and development of techniques for its detection Quarterly report, 1 May - 31 Aug. 1968

Mechanism of stress corrosion cracking in aluminum alloys and techniques for detection of surface defect

Derivations of the Core Functions of the Maximum Entropy Theory of Ecology

The Maximum Entropy Theory of Ecology (METE), is a theoretical framework of macroecology that makes a variety of realistic ecological predictions about how species richness, abundance of species, metabolic rate distributions, and spatial aggregation of species interrelate in a given region. In the METE framework, "ecological state variables" (representing total area, total species richness, total abundance, and total metabolic energy) describe macroecological properties of an ecosystem. METE incorporates these state variables into constraints on underlying probability distributions. The method of Lagrange multipliers and maximization of information entropy (MaxEnt) lead to predicted functional forms of distributions of interest. We demonstrate how information entropy is maximized for the general case of a distribution, which has empirical information that provides constraints on the overall predictions. We then show how METE's two core functions are derived. These functions, called the "Spatial Structure Function" and the "Ecosystem Structure Function" are the core pieces of the theory, from which all the predictions of METE follow (including the Species Area Relationship, the Species Abundance Distribution, and various metabolic distributions). Primarily, we consider the discrete distributions predicted by METE. We also explore the parameter space defined by the METE's state variables and Lagrange multipliers. We aim to provide a comprehensive resource for ecologists who want to understand the derivations and assumptions of the basic mathematical structure of METE.USDA; Bridging Biodiversity and Conservation Science programOpen access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

The anonymous reviewer:the relationship between perceived expertise and the perceptions of peer feedback in higher education

Peer feedback often has positive effects on student learning processes and outcomes. However, students may not always be honest when giving and receiving peer feedback as they are likely to be biased due to peer relations, peer characteristics and personal preferences. To alleviate these biases, anonymous peer feedback was investigated in the current research. Research suggests that the expertise of the reviewer influences the perceived usefulness of the feedback. Therefore, this research investigated the relationship between expertise and the perceptions of peer feedback in a writing assignment of 41 students in higher education with a multilevel analysis. The results show that students perceive peer feedback as more adequate when knowing the reviewer perceives him/herself to have a high level of expertise. Furthermore, the results suggest that students who received feedback from a peer who perceives their expertise as closer to the reviewee’s own perceived expertise was more willing to improve his or her own assignment

Study of the general mechanism of stress corrosion of aluminum alloys and development of techniques for its detection Quarterly report, 1 Dec. 1967 - 29 Feb. 1968

Stress corrosion of aluminum alloys and techniques for its detectio

Study of the general mechanism of stress corrosion of aluminum alloys and development of techniques for its detection Annual summary report, 2 Jun. 1967 - 1 Jun. 1968

Stress corrosion cracking of high strength aluminum alloys investigated by electrochemical, mechanical, and electron microscopic technique

Dietary calcium decreases but short-chain fructo-oligosaccharides increase colonic permeability in rats

An increased intestinal permeability is associated with several diseases. Nutrition can influence gut permeability. Previously, we showed that dietary Ca decreases whereas dietary short-chain fructo-oligosaccharides (scFOS) increase intestinal permeability in rats. However, it is unknown how and where in the gastrointestinal tract Ca and scFOS exert their effects. Rats were fed a Western low-Ca control diet, or a similar diet supplemented with either Ca or scFOS. Lactulose plus mannitol and Cr-EDTA were added to the diets to quantify small and total gastrointestinal permeability, respectively. Additionally, colonic tissue was mounted in Ussing chambers and exposed to faecal water of these rats. Dietary Ca immediately decreased urinary Cr-EDTA excretion by 24 % in Ca-fed rats compared with control rats. Dietary scFOS increased total Cr-EDTA permeability gradually with time, likely reflecting relatively slow gut microbiota adaptations, which finally resulted in a 30 % increase. The lactulose: mannitol ratio was 15 % higher for Ca-fed rats and 16 % lower for scFOS-fed rats compared with control rats. However, no dietary effect was present on individual urinary lactulose and mannitol excretion. The faecal waters did not influence colonic permeability in Ussing chambers. In conclusion, despite effects on the lactulose: mannitol ratio, individual lactulose values did not alter, indicating that diet did not influence small-intestinal permeability. Therefore, both nutrients affect permeability only in the colon: Ca decreases, while scFOS increase colonic permeability. As faecal water did not influence permeability in Ussing chambers, probably modulation of mucins and/or microbiota is important for the in vivo effects of dietary Ca and scFOS

Trace Mineral Leaching from Equine Compost

Mineral leaching from compost can be environmentally disruptive. Little information is available regarding trace mineral leaching from equine-sourced compost. The objective of this study was to quantify the mineral content and leaching potential of compost produced from feces of horses fed different amounts and forms (organic or inorganic) of trace minerals. Nine horses were fed three treatments in a 3 × 3 replicated Latin Square design. The dietary treatments were provided as a daily pellet: CON (pellet without added trace minerals), ING (added inorganic trace minerals), and ORG (added organic trace minerals). The added trace minerals were Co, Cu, Mn, and Zn. Feces were collected from each horse after a 16-day feeding period, combined with straw, composted, and then subjected to simulated rainfall to measure mineral mobility. Concentrations of Co, Cu, Mn, and Zn were greater in ING and ORG compared to CON compost (p \u3c 0.05); additionally, ING had greater Zn than ORG compost (p \u3c 0.05). More Cu leached from ING and ORG compared to CON (p \u3c 0.05). The most Zn leached from ING, followed by ORG, and the least amount leached from CON compost (p \u3c 0.05). Dietary trace mineral intake affected the trace mineral concentration in the compost and amount available to leach during rainfall events

The effect of enclosure type on the behavior and heart rate of captive coyotes

The potential for captivity to elicit changes in animal behavior and physiology is well known. Recent research on captive populations has examined the effect of feeding protocols, enclosure types, and enrichment programs on indices of stress and displays of species-typical behaviors. We investigated the impact of enclosure type upon captive coyotes (Canis latrans) by examining differences in coyote behavior and heart rate, among 3.3m2 kennels (K), 65.5m2 small pens (S), and 1000m2 large pens (L). Time budgets and repertoire of species-specific behaviors were compared among each enclosure type and to a sample of wild (W) coyotes. Baseline heart rates and heart rate (HR) responses to food delivery and fecal collection (measured as mean heart rate and latency of heart rate to return to baseline) were also compared among treatments. We found that behavioral budgeting, but not repertoire, differed significantly among enclosure types. Relative to small and large pen enclosures, coyotes maintained in kennels exhibited the greatest amount of stereotypic behavior (P \u3c 0.0001). Coyotes kept in large pens were most similar to wild coyotes in the percentage of time they spent performing exploratory (K: 2.7%; S: 4.9%; L: 8.5%; W: 12.0%) and stand and scan (K: 8.0%; S: 16.4%; L: 22.0%; W: 22.3%) behaviors. Heart rate analysis showed that baseline heart rates and heart rate responses to food delivery did not differ significantly among enclosure types. Mean heart rate responses to fecal collection were significantly higher for kennel coyotes than for those maintained in large pens (P = 0.04). Similarly, latency to return to baseline was significantly higher in kennels than in small and large pens (P = 0.001). These results suggest that enclosure type does influence coyote behavior and heart rate responses to some human activities

Coccolithophore fluxes in the open tropical North Atlantic: influence of thermocline depth, Amazon water, and Saharan dust

Coccolithophores are calcifying phytoplankton and major contributors to both the organic and inorganic oceanic carbon pumps. Their export fluxes, species composition, and seasonal patterns were determined in two sediment trap moorings (M4 at 12 degrees N, 49 degrees W and M2 at 14 degrees N, 37 degrees W) collecting settling particles synchronously from October 2012 to November 2013 at 1200 m of water depth in the open equatorial North Atlantic. The two trap locations showed a similar seasonal pattern in total coccolith export fluxes and a predominantly tropical coccolithophore settling assemblage. Species fluxes were dominated throughout the year by lower photic zone (LPZ) taxa (Florisphaera profunda, Gladiolithus flabellatus) but also included upper photic zone (UPZ) taxa (Umbellosphaera spp., Rhabdosphaera spp., Umbilicosphaera spp., Helicosphaera spp.). The LPZ flora was most abundant during fall 2012, whereas the UPZ flora was more important during summer. In spite of these similarities, the western part of the study area produced persistently higher fluxes, averaging 241 x 10(7) +/- 76 x 10(7) coccoliths m(-2) d(-1) at station M4 compared to only 66 x 10(7) +/- 31 x 10(7) coccoliths m(-2) d(-1) at station M2. Higher fluxes at M4 were mainly produced by the LPZ species, favoured by the westward deepening of the thermocline and nutricline. Still, most UPZ species also contributed to higher fluxes, reflecting enhanced productivity in the western equatorial North Atlantic. Such was the case of two marked flux peaks of the more opportunistic species Gephyrocapsa muellerae and Emiliania huxleyi in January and April 2013 at M4, indicating a fast response to the nutrient enrichment of the UPZ, probably by wind-forced mixing. Later, increased fluxes of G. oceanica and E. huxleyi in October-November 2013 coincided with the occurrence of Amazon-River-affected surface waters. Since the spring and fall events of 2013 were also accompanied by two dust flux peaks, we propose a scenario in which atmospheric dust also provided fertilizing nutrients to this area. Enhanced surface buoyancy associated with the river plume indicates that the Amazon acted not only as a nutrient source, but also as a surface density retainer for nutrients supplied from the atmosphere. Nevertheless, lower total coccolith fluxes during these events compared to the maxima recorded in November 2012 and July 2013 indicate that transient productivity by opportunistic species was less important than "background" tropical productivity in the equatorial North Atlantic. This study illustrates how two apparently similar sites in the tropical open ocean actually differ greatly in ecological and oceanographic terms. The results presented here provide valuable insights into the processes governing the ecological dynamics and the downward export of coccolithophores in the tropical North Atlantic.Netherlands Organization for Scientific Research (NWO) [822.01.008]; European Research Council (ERC) [311152]; University of Bremen; European Union [600411]info:eu-repo/semantics/publishedVersio