Low alpha power (7.5–9.5 Hz) changes during positive and negative affective learning

There is evidence that the positive and the negative word lists of the Affective Auditory Verbal Learning Test (AAVL) are useful with regard to mood induction. To date, however, changes in brain activation, as indicated by quantitative electroencephalographic recording, have not been examined. Thus, changes in low alpha power (7.5–9.5 Hz) were examined during and after completion of the positive or the negative learning list of the AAVL among 37 undergraduate men and women. Three primary findings from the study include the following: (1) Previously reported recall patterns were replicated; (2) participants who completed the negative list reported a significant decline in mood state at the end of the session; and (3) participants who completed the negative word list evidenced a significant reduction in low alpha power (in comparison with baseline) within the parietal regions. The findings noted above are seemingly counter to contemporary theories of mood regulation (i.e., asymmetrical changes in anterior activity, rather than changes in parietal regions). Although the AAVL may have limited utility as a tool for mood induction, it may serve as a functional tool for examination of the cerebral processes associated with affective verbal memory

Oxide formation and anodic polarization behavior of thin films of amorphous and crystalline Fe---Cr---P alloys prepared by ion beam mixing

An experimental program has been conducted to determine the effect of phosphorus on the corrosion and passivation behavior of Fe---Cr---P alloys. Chemically homogeneous 60 nm films of Fe---10Cr---xP (x from 0 to 35 at.%) were prepared by multilayer evaporation followed by ion beam mixing with Kr+ ions. Films with a phosphorus content of at least 25 at.% were found to be entirely amorphous, while films with 15 at.% P consisted of both amorphous and bcc phases. Recrystallization of the amorphous phase was accomplished by heating the samples to 450[deg]C in a purified argon flow furnace.Electrochemical polarization tests in an acid solution have shown the Fe---10Cr---xP films to be more corrosion resistant than Fe---10Cr, with the corrosion resistance increasing with the amount of P present. The corrosion resistance is not significantly affected when the amorphous films are recrystallized, indicating that the behavior is chemically controlled and not a result of the amorphous structure. When examined by XPS, the phosphorus appears to enhance passivation by encouraging Cr enrichment in the oxide and by incorporating in the oxide as phosphate.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29265/1/0000323.pd

Chemical and structural effects of phosphorus on the corrosion behavior of ion beam mixed Fe-Cr-P alloys

An experimental program was conducted to determine the mechanisms by which phosphorus affects the corrosion and passivation behavior of Fe-Cr-P alloys. To identify separately the effects of structure and chemistry on the corrosion behavior, thin films of Fe-10Cr-xP (0xat.%) were prepared by ion beam mixing. Films with a phosphorus content greater than approximately 20 at.% were found to be entirely amorphous. Devitrification of the amorphous phase was accomplished by heating the samples to 450 [deg]C in an inert environment.Standard polarization tests of the alloys in sulfuric acid (with and without Cl-) indicated that the films containing phosphorus were more corrosion resistant than Fe-10Cr, at both active and passive potentials. There was a monotonic relationship between the amount of phosphorus in the alloy and the corrosion resistance, with the open-circuit corrosion rate of Fe-10Cr-35P nearly four orders of magnitude lower than that of Fe-10Cr. Devitrification of the alloys had no significant effect on the corrosion rate, indicating that the primary effect of phosphorus is chemical in nature, and not structural. The passive oxides were depth-profiled using X-ray photoelectron spectroscopy, which indicated that phosphorus was a primary constituent, as phosphate. The presence of phosphate in the passive oxides reduced the overall corrosion rate directly, by suppressing anodic dissolution. The presence of phosphorus did enhance chromium enrichment in the oxide, but that was not thought to be the primary mechanism by which phosphorus increased the corrosion resistance.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30101/1/0000473.pd

Thermal extrusion of a non-linear viscoelastic solid inside a long cylindrical tube

An analysis is presented for the axial extrusion of an expanding viscoelastic solid inside a long cylindrical tube. Both differential thermal expansion and expansion of gas bubbles in the solid are considered as driving mechanisms. Finite element calculations are used to illustrate the details of the behavior of the system. The response is shown to be initially elastic followed by the development of a boundary layer near the free surface where the pressure gradients are sufficiently large to cause axial viscous flow. Simple boundary layer equations are derived to describe this flow. Results using these equations agree well with the results of the finite element calculations. The theory is applied to the extrusion of uranium-based metallic reactor fuel during overheating transients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47818/1/466_2004_Article_BF00282136.pd

Seasonal and intraspecific variability of chlorophyll fluorescence, pigmentation and growth of Pinus ponderosa subjected to elevated CO{sub 2}

Atmospheric CO{sub 2}2 is expected to double in the next century, and these increases will have substantial impact on forest ecosystems. However, the database on the effects of elevated CO{sub 2} on forests is limited, and the extent of intraspecific variability remains unknown. We are investigating the effects of elevated CO{sub 2} on the intraspecific variability of quantum yield (as measured through chlorophyll fluorescence Fv/Fm ratio) and pigmentation, and how these are correlated to variability in growth. Four-year-old Pinus ponderosa seedlings were obtained from nine different sources across California. These seedlings were grown in standard outdoor exposure chambers for sixteen months at either ambient levels of CO{sub 2}, ambient+175ppm CO{sub 2}, or ambient+350ppm CO{sub 2}. The seedlings were periodically measured for growth, pigmentation, and chlorophyll fluorescence. The results showed a variable growth response of the nine sources during all measurement periods. Increasing CO{sub 2} resulted in a decrease in Fv/Fm among sources ranging from {minus}2.1% to {minus}23.2% in February, and 3.1% to {minus}12.5% in June. The source that had the best growth throughout the study, also had a minimal reduction in quantum yield (Fv/Fm) in the presence of elevated CO{sub 2}. For the seedlings of fastest growing sources, the correspondence between total growth and chlorophyll fluorescence was strongest during the February measurement period. Our results also showed a significant reduction in pigmentation due to increased CO{sub 2}. There are at least three explanations for the different responses during each measurement periods. First, the trees could be adapting favorably to increasing CO{sub 2}. Secondly, 1993 needles could be under less physiological stress than the current year needles. Third, there is a seasonal effect dependent upon temperature or light which is influencing the Fv/Fm ratio and pigmentation

Corrosion and mechanical behavior of ion implanted bearing steels for improved fretting behavior

Ion implantation of AISI 52100 and 1070 steels was conducted in order to improve the corrosion, wear and ultimately the fretting behavior of the steels. Implantations consisted of 1 x 1017 Ta+ cm-2, 3 x 1017 Ti+ cm-2 + 1.5 x 1017 C+ cm-2, and 3.1 x 1017 Ti+ cm-2 + 1.55 x 1017 N+2 cm-2. All implantations were successful in improving the corrosion resistance. On average, the peak anodic current was reduced by over 300 mV, the passivation potential was reduced, and the pitting potential was increased by over 1000 mV in 0.01 M NaCl. Ti + C and Ti + N implantations increased the load-carrying capacity in lubricated scuffing tests by 60% and 40% respectively. Ta produced no improvement in scuffing resistance. Ti + N implantation increased the hardness by 25% over the unimplanted steel and both Ti + C and Ta implantation reduced the surface hardness. Fretting wear was reduced only slightly in the Ta implanted sample and increased in both the Ti + C and Ti + N implanted samples with the latter showing 4-5 times the weight loss as the unimplanted sample. The correlation between fretting and hardness supports a mechanism in which the hard surface layer breaks into fine particles which act as an abrasive under the intense load of the balls.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31416/1/0000333.pd

The effect of elevated carbon dioxide on a Sierra-Nevadan dominant species: Pinus ponderosa

The impact of increasing atmospheric C0{sub 2} has not been fully evaluated on western coniferous forest species. Two year old seedlings of Pinusponderosa were grown in environmentally controlled chambers under increased C0{sub 2} conditions for 6 months. These trees exhibit morphological, physiological, and biochemical alterations when compared to our controls. Analysis of whole plant biomass distribution has shown no significant effect to the root to shoot ratios, however needles subjected to elevated C0{sub 2} exhibited an increased overall specific needle mass and a decreased total needle area. Morphological changes at the needle level included decreased mesophyll to vascular tissue 91 ratio and variations in starch storage in chloroplasts. The elevated CO{sub 2} increased internal CO{sub 2} concentrations and assimilation of carbon. Biochemical assays revealed that ribulose-bisphosphate carboxylase specific activities increased on per unit area basis with C0{sub 2} treatment levels. Sucrose phosphate synthase (SPS) activities exhibited an increase of 55% in the 700 uL L{sup {minus}1} treatment. These results indicate that the sink-source relationships of these trees have shifted carbon allocation toward above ground growth, possibly due to transport limitations

University Physics Volume 2

University Physics is a three-volume collection that meets the scope and sequence requirements for two- and three-semester calculus-based physics courses. Volume 1 covers mechanics, sound, oscillations, and waves. Volume 2 covers thermodynamics, electricity and magnetism, and Volume 3 covers optics and modern physics. This textbook emphasizes connections between theory and application, making physics concepts interesting and accessible to students while maintaining the mathematical rigor inherent in the subject. Frequent, strong examples focus on how to approach a problem, how to work with the equations, and how to check and generalize the result.https://commons.erau.edu/oer-textbook/1002/thumbnail.jp