Marcy G. Beyer Interview

Transcript of an oral history interview with Marcy G. Meyer by John Ernst on her experiences during the Vietnam War on May 31, 1997

Developmental profile and regulation of brain estrogen synthesis by aromatase

Aromatase cytochrome P450 enzyme catalyzes the formation of estrogen from androgen in distinct regions of the vertebrate brain. During neural development, local estrogen synthesis is required for the sexual differentiation of male brain characteristics and the differentiation of neural circuits Involved in sex-specific behaviors and neuroendocrine functions. A common phenomenon in all species studied so far is that the male brain displays much higher and brain region-specific aromatase expression during distinct periods of brain development than the female one. An important question arising from these findings is which factor(s) play a role in regulating estrogen formation in a sex- and brain region-specific fashion. Among the factors investigated, androgens have been found to be the most powerful regulators of brain aromatase. In vitro experiments using primary cell cultures of embryonic mouse brains showed that sex differences in aromatase activity in hypothalamic cells develop, at first, independently of gonadal steroids. Later during embryonic development, aromatase expression is regulated in a region- and sex-specific way by circulating androgens. Hypothalamic aromatase neurons are most sensitive to androgen exposure whereas cortical and midbrain ones are insensitive. Moreover, androgens affect morphological maturation of aromatase-immunoreactive cells by stimulating neurite outgrowth and dendritic arborization. These findings suggest that androgens function as major morphogenetic factors during the differentiation of the mammalian hypothalamic aromatase system. During late embryonic development and perinatally, androgen levels differ between sexes, being significantly higher in males. This time period corresponds exactly to the developmental stage when aromatase activities are highest in the male hypothalamus. It seems plausible therefore that higher androgen concentrations in the male circulation during ontogenesis are causally connected with the observed sex differences in hypothalamic aromatase activity.Biomedical Reviews 1997; 7: 41-50

Thermal imaging of increment cores: a new method to estimate sapwood depth in trees

The cells in tree sapwood form a network of interconnected conduits which enables the transport of water and nutrients from the tree roots to the canopy. Sapwood depth must be assessed when tree water use is estimated from sap flow velocities. However, current approaches to assess sapwood depth are either not applicable universally, or require expensive instruments, the application of chemicals or laborious field efforts. Here, we present a new method, which estimates sapwood depth by thermal imaging of increment cores. Using a low-cost thermal camera for mobile devices, we show that the sapwood-heartwood boundary is detectable by a sharp increase in temperature. Estimated sapwood depths agree with dye estimates (R-2 = 0.84). We tested our approach on a broad range of temperate and tropical tree species: Quercus robur, Pinus sylvestris, Swietenia macrophylla, Guazuma ulmifolia, Hymenaea courbaril, Sideroxylon capiri and Astronium graveolens. In nearly all species, the methods agreed within 0.6 cm. Thermal imaging of increment cores provides a straightforward, low-cost, easy-to-use, and species-independent tool to identify sapwood depth. It has further potential to reveal radial differences in sapwood conductivity, to improve water balance estimations on larger scales and to quickly develop allometric relationships

Complex basal conditions influence flow at the onset of the Northeast Greenland Ice Stream

The onset and high upstream ice surface velocities of the North East Greenland Ice Stream (NEGIS) are not yet well reproducible in ice sheet models. A major uncertainty remains the understanding of basal sliding and a parameterization of basal conditions. In this study, we assess the slow-flowing part of the NEGIS in a systematic analysis of the basal conditions and investigate the increased ice flow. We analyze the spectral basal roughness in correlation with basal return power from an airborne radar survey with AWIs ultra-wideband radar system in 2018 and compare our results with current ice flow geometry and ice surface flow. We observe a roughness anisotropy where the ice stream widens, indicating a change from a smooth and soft bed to a harder bedrock as well as the evolution of elongated subglacial landforms. In addition, at the upstream part of the NEGIS we find a clear zoning of the bedrock return power, indicating an increased water content at the base of the ice stream. At the downstream part, we observe an increased bedrock return power throughout the entire width of the ice stream and outside its margins, indicating enhanced melting and the distribution of basal water beyond the shear zones

Optically addressing single rare-earth ions in a nanophotonic cavity

We demonstrate optical probing of spectrally resolved single Nd rare-earth ions in yttrium orthovanadate. The ions are coupled to a photonic crystal resonator and show strong enhancement of the optical emission rate via the Purcell effect, resulting in near radiatively limited single photon emission. The measured high coupling cooperativity between a single photon and the ion allows for the observation of coherent optical Rabi oscillations. This could enable optically controlled spin qubits, quantum logic gates, and spin-photon interfaces for future quantum networks