Ultra-high sensitivity magnetic field and magnetization measurements with an atomic magnetometer

We describe an ultra-sensitive atomic magnetometer using optically-pumped potassium atoms operating in spin-exchange relaxation free (SERF) regime. We demonstrate magnetic field sensitivity of 160 aT/Hz$^{1/2}$ in a gradiometer arrangement with a measurement volume of 0.45 cm$^3$ and energy resolution per unit time of $44 \hbar$. As an example of a new application enabled by such a magnetometer we describe measurements of weak remnant rock magnetization as a function of temperature with a sensitivity on the order of 10$^{-10}$ emu/cm$^3$/Hz$^{1/2}$ and temperatures up to 420$^\circ$C

Zero gravity and cardiovascular homeostasis. The relationship between endogenous hyperprolactinemia and plasma aldosterone

Prolactin, thyrotropin and aldosterone were measured by radioimmunoassay and plasma renin activity by the radioimmunoassay of angiotensin I in normal women before and after the intravenous injection of 200 micrograms of thyrotropin releasing hormone. Prolactin increased at 15 minutes following thyrotropin releasing hormone. Plasma renin activity was not different from control levels during the first hour following the administration of thyrotropin releasing hormone, nor did the plasma aldosterone concentration differ significantly from the control levels during this period. However, with upright posture, an increase in aldosterone and in plasma renin activity was noted, demonstrating a normal capacity to secrete aldosterone. Similarly, no change in aldosterone was seen in 9 patients with primary hypothyroidism given thyrotropin releasing hormone, despite the fact that the increase in prolactin was greater than normal. These data demonstrate that acutely or chronically elevated serum prolactin levels do not result in increased plasma aldosterone levels in humans

Mary

https://digitalcommons.library.umaine.edu/mmb-vp/4323/thumbnail.jp

Sedimentary Iron Cycling and the Origin and Preservation of Magnetization in Platform Carbonate Muds, Andros Island, Bahamas

Carbonate muds deposited on continental shelves are abundant and well-preserved throughout the geologic record because shelf strata are difficult to subduct and peritidal carbonate units often form thick, rheologically strong units that resist penetrative deformation. Much of what we know about pre-Mesozoic ocean chemistry, carbon cycling, and global change is derived from isotope and trace element geochemistry of platform carbonates. Paleomagnetic data from the same sediments would be invaluable, placing records of paleolatitude, paleogeography, and perturbations to the geomagnetic field in the context and relative chronology of chemostratigraphy. To investigate the depositional and early diagenetic processes that contribute to magneitzation in carbonates, we surveyed over 500 core and surface samples of peritidal, often microbially bound carbonate muds spanning the last not, vert, similar 1000 yr and deposited on top of Pleistocene aeolianites in the Triple Goose Creek region of northwest Andros Island, Bahamas. Sedimentological, geochemical, magnetic and ferromagnetic resonance properties divide the sediment columns into three biogeochemical zones. In the upper sediments, the dominant magnetic mineral is magnetite, produced by magnetotactic bacteria and dissimiliatory microbial iron metabolism. At lower depths, above or near mean tide level, microbial iron reduction dissolves most of the magnetic particles in the sediment. In some cores, magnetic iron sulfides precipitate in a bottom zone of sulfate reduction, likely coupled to the oxidation of decaying mangrove roots. The remanent magnetization preserved in all oriented samples appears indistinguishable from the modern local geomagnetic field, which reflects the post-depositional origin of magnetic particles in the lower zone of the parasequence. While we cannot comment on the effects of late-stage diagenesis or metamorphism on remanence in carbonates, we postulate that early-cemented, thin-laminated parasequence tops in ancient peritidal carbonates are mostly likely to preserve syn-depositional paleomagnetic directions and magnetofossil stratigraphies

elicit: A system for detecting insiders who violate need-to-know

Abstract. Malicious insiders do great harm and avoid detection by using their legitimate privileges to steal information that is often outside the scope of their duties. Based on information from public cases, consultation with domain experts, and analysis of a massive collection of information-use events and contextual information, we developed an approach for detecting insiders who operate outside the scope of their duties and thus violate need-to-know. Based on the approach, we built and evaluated elicit, a system designed to help analysts investigate insider threats. Empirical results suggest that, for a specified decision threshold of .5, elicit achieves a detection rate of .84 and a false-positive rate of .015, flagging per day only 23 users of 1, 548 for further scrutiny. It achieved an area under an roc curve of .92

Global transcriptome analysis reveals circadian regulation of key pathways in plant growth and development

Transcript abundance of roughly a third of expressed Arabidopsis thaliana genes is circadian-regulated

Estudio del movimiento de madera de consumo en el departamento del Magdalena

En el siguiente trabajo se expresa la necesidad de las investigaciones en el campo de la tecnología de la madera y productos forestales, porque conocemos que el desarrollo económico del País requiere una utilización racional de todos sus recursos renovables más abundantes, ocupando actualmente una extensión aproximada de 50 millones de Há., que equivalen al 45% del total de la superficie de Colombia. Su utilización racional es, sin embargo, en extremo deficiente en los bosques tropicales accesibles y actualmente en explotación se extraen selectivamente algunas pocas especies, quedando bosques pobres en especies comerciales y con fuertes disturbios ecológicos. Esta utilización deficiente, que es realmente el despilfarro de un capital necesario al desarrollo del País, solo puede corregirse mediante la ejecución de investigaciones planificadas con un enfoque global del problema, en cuya realización se coordinen los recursos humanos y económicos que se dispone actualmente