MAO-A and the EEG Recognition Memory Signal in Left Parietal Cortex

A key part of episodic memory, or memory for the events of our lives, is recognition memory. Recognition memory is the ability to remember previously encountered stimuli. Studies have linked recognition memory to the old/new effect, an EEG indicator of stimulus familiarity. Monoamine oxidase A (MAO-A) is an enzyme that catalyzes monoamines, leading to the depletion of norepinephrine, epinephrine, serotonin, and dopamine. MAO-A is more efficiently transcribed in individuals with a 4 repeating sequence variation (4R) of the MAO-A gene leading to less monoamine availability. As many of these monoamines have been linked to episodic memory, we hypothesized that individuals homozygous for the 4R MAO-A polymorphism would show differences in mean EEG signal amplitudes during recognition memory. EEG data was recorded as participants viewed both new words and words that had been previously presented. Our results show that mean peak amplitudes over the left parietal cortex 500-800 ms post-stimulus presentation for hits were greater than those for correct rejections, indicating the old/new effect. Critically, our results revealed an interaction between mean hit and correct rejection amplitude over the left parietal cortex and MAO-A group. Individuals homozygous for the 4R variation (the High MAO-A group) do not show an old/new effect due to increased correct rejection amplitudes. These results suggest that less monoamine availability leads to new stimuli being identified as old by the left parietal cortex

Exact factorization of correlation functions in 2-D critical percolation

By use of conformal field theory, we discover several exact factorizations of higher-order density correlation functions in critical two-dimensional percolation. Our formulas are valid in the upper half-plane, or any conformally equivalent region. We find excellent agreement of our results with high-precision computer simulations. There are indications that our formulas hold more generally.Comment: 6 pages, 3 figures. Oral presentation given at STATPHYS 23. V2: Minor additions and corrections, figures improve

Metallographic and Magentic Properties of a Yamato Iron Meteorite─Yamato-75-105

A Yamato iron meteroite, Yamato-75-105, examined chemically, metallographically and magnetically, has revealed that the major elements of the metal base of this iron meteorite are 5.65% Ni, 1.0% P, and 0.52% Co, in addition to Fe occupying the most parts. From the chemical composition and the microstructure, this iron meteorite can be classified as a reheated hexahedrite, i. e. a Ni-poor ataxite. An "ablation zone" about 2mm in thickness on the flat surface indicates an extensive reheating on entry into the earth\u27s atmosphere although traces of the original single-crystal features remain. Within the matrix of kamacite (95% Fe and 5% Ni) composition, Fe-Ni phosphide (schribersite ; 75% Fe, 10% Ni and 15% P) grains are enveloped by high-P kamacite of α-phase (91% Fe, 7% Ni and 2% P). These structures suggest that this meteorite specimen was reheated to above 1000℃. The acicular grain structure of the kamacite matrix indicates a rapid cooling rate after the reheating. Both metallographic and magnetic analyses have consistently revealed the above-mentioned conclusion

Book Reviews

Book Review

A disk census for the nearest group of young stars: Mid-infrared observations of the TW Hydrae Association

A group of young, active stars in the vicinity of TW Hydrae has recently been identified as a possible physical association with a common origin. Given its proximity ($\sim$50 pc), age ($\sim$10 Myr) and abundance of binary systems, the TW Hya Association is ideally suited to studies of diversity and evolution of circumstellar disks. Here we present mid-infrared observations of 15 candidate members of the group, 11 of which have no previous flux measurements at wavelengths longer than 2$\mu$m. We report the discovery of a possible 10$\mu$m excess in CD -33$^{\circ}$7795, which may be due to a circumstellar disk or a faint, as yet undetected binary companion. Of the other stars, only TW Hya, HD 98800, Hen 3-600A, and HR 4796A -- all of which were detected by IRAS -- show excess thermal emission. Our 10$\mu$m flux measurements for the remaining members of the Association are consistent with photospheric emission, allowing us to rule out dusty inner disks. In light of these findings, we discuss the origin and age of the TW Hya Association as well as implications for disk evolution timescales.Comment: 10 pages and 1 PostScript figure, accepted for publication in The Astrophysical Journal Letter

Ground-Water and Surface-Water Hydrology of Camp Swift, Bastrop County, Texas

Ground-water and surface-water investigations of Camp Maxey, Lamar County, Texas, were conducted to provide the Texas Army National Guard information needed to preserve environmental quality and resources while planning and conducting training and preparedness activities. Spatial information such as surface geology, watersheds, elevation data, floodplains, well locations, and water levels were converted to digital files and submitted to the Texas Army National Guard Geographic Information System office at Camp Mabry, Austin, Texas, for future use in managing the training facility. Similar investigations were conducted at Camps Barkeley, Bowie, Mabry, and Swift, and at Fort Wolters. Results of those studies are presented separately. Previously published reports and public data files were examined to obtain background information on the camp and surrounding area. These data were used to guide more focused studies on the training facility. Ground-water studies included locating existing wells in and near the camp, installing new wells as needed, testing and sampling selected wells, determining ground-water levels, chemical compositions, and aquifer hydraulic properties, and developing a conceptual model of ground-water flow. Surface-water studies focused on delineating watersheds and mapping floodplains.Bureau of Economic Geolog

Ground-Water and Surface-Water Hydrology of Camp Bowie, Brown County, Texas

Data for this report is available at the Texas Data Repository: https://doi.org/10.18738/T8/UMVGJPGround-water and surface-water investigations of Camp Bowie, Brown County, Texas, were conducted to provide the Texas Army National Guard information needed to preserve environmental quality and resources while planning and conducting training and preparedness activities. Spatial information such as surface geology, watersheds, elevation data, floodplains, well locations, and water levels were converted to digital files and submitted to the Texas Army National Guard Geographic Information System office at Camp Mabry, Austin, Texas, for future use in managing the training facility. Similar investigations were conducted at Camps Barkeley, Mabry, Maxey, and Swift, and at Fort Wolters. Results of those studies are presented separately. Previously published reports and public data files were examined to obtain background information on the camp and surrounding area. These data were used to guide more focused studies on the training facility. Ground-water studies included locating existing wells on and near the camp, installing new wells as needed, testing and sampling selected wells, determining ground-water levels, chemical compositions, and aquifer hydraulic properties, and developing a conceptual model of ground-water flow. Surface-water studies focused on delineating watersheds and mapping floodplains.Bureau of Economic Geolog

Ground-Water and Surface-Water Hydrology of Fort Wolters, Parker and Palo Pinto Counties, Texas

Ground-water and surface-water investigations of Camp Maxey, Lamar County, Texas, were conducted to provide the Texas Army National Guard information needed to preserve environmental quality and resources while planning and conducting training and preparedness activities. Spatial information such as surface geology, watersheds, elevation data, floodplains, well locations, and water levels were converted to digital files and submitted to the Texas Army National Guard Geographic Information System office at Camp Mabry, Austin, Texas, for future use in managing the training facility. Similar investigations were conducted at Camps Barkeley, Bowie, Mabry, and Swift, and at Fort Wolters. Results of those studies are presented separately. Previously published reports and public data files were examined to obtain background information on the camp and surrounding area. These data were used to guide more focused studies on the training facility. Ground-water studies included locating existing wells in and near the camp, installing new wells as needed, testing and sampling selected wells, determining ground-water levels, chemical compositions, and aquifer hydraulic properties, and developing a conceptual model of ground-water flow. Surface-water studies focused on delineating watersheds and mapping floodplains.Bureau of Economic Geolog