Operator related attenuation effects in radiometric surveys

Radiometric surveys using airborne, vehicular mounted or backpack detector systems are increasingly used to identify and evaluate complex distributions of radioactivity in the environment. The signals detected depend on the energy and spatial distribution of radioactive sources, the material properties of the environment and the specific properties of the detector systems employed. Materials in close vicinity to the detector such as housings, and intermediate materials may have a critical impact on detection efficiency, and must therefore be taken into account in calibration. This study evaluates the effect of shielding by the body of the operator in backpack surveys. Controlled experiments using point sources and absorbers, chosen to represent the form and composition of human tissue, were conducted, and coupled to an analytical radiation transport model to estimate attenuation factors for mapping of 137Cs. In this way generic factors to correct for this effect using portable spectrometers have been determined. The results compare well with observations at sampled calibration sites in Fukushima and the Solway area in Scotland. Reductions of the 137Cs full-energy peak intensity between 20% and 30% may be expected depending on operator stature and the offset position of backpack systems. Similar effects may be present for other radiometric systems carried by a human operator

Evolución geológica en la cuenca baja del río Colorado durante el cenozoico, Patagonia Norte, Argentina

Climatic changes and eustatic sea levels have been assumed to be the most important controllers of the Colorado River alluvial fan in northern Patagonia. Although the alluvial fan occurs in a region considered tectonically stable, there are pieces of evidence that the Miocene Andean orogeny has reactivated inherited structures, with subsequent geomorphological changes that date back to the Pleistocene. Besides, the clear evidence of neotectonism in the region and their effects on the evolution of this fan, it has not been studied in detail yet. In this study, we map and analyze six sections outcropping in different terraces of the alluvial fan with the primary aim of disentangling the role of tectonism, climate and eustatic changes on the evolution of the alluvial fan. This study is part of a bigger project aimed to understand the origin of the shallow lakes occurring in northern Patagonia. Our results indicate that the alluvial fan of the Colorado River was established in the area around the Middle Pleistocene. Evidence of deformations in Miocene to Pleistocene units indicates significant neotectonism during the Upper Pleistocene. By the Pleistocene-Holocene transition, tectonism produced incision generating a set of terraces. After this time, an important climate change from semiarid to arid favored the calcretization of some terraces. By the Pleistocene-Middle Holocene, the terraces were covered by ancient eolian sediment accumulated during dry conditions. By the Middle Holocene, a broad alluvial fan developed in the region under a warmer and more humid climate generating the Alluvial Colorado River-III deposit at the T3 terrace. In the late Holocene, aggradation process was favored by a high sea level and temperate-arid climate, producing T4 terrace. At the same time, this climate condition favored the local deflation-sedimentation processes that resulted in the deposition of modern eolian deposits (mE) over the T3 terrace. The depressions generated by the deflation were, later on, occupied by shallow lakes when the climate turn more humid. Subsequently, during regressive sea level condition, ca. 2000 years BP, the T4 terrace was partially eroded and the modern alluvial plain formed.La evolución geológica y morfológica del abanico aluvial del río Colorado en el norte de Patagonia ha sido explicada, en su zona distal, como resultado de cambios eustáticos y climáticos. A pesar de que el abanico se encuentra en una región considerada como una zona tectónicamente estable, hay evidencia de que la orogenia andina durante el Mioceno reactivó estructuras preexistentes y produjo cambios geomorfológicos asignados al Pleistoceno. Sin embargo, la influencia de la tectónica en la evolución del abanico aluvial del río Colorado no ha sido aún estudiada. En este trabajo, se levantaron y estudiaron seis secciones que afloran en distintas terrazas del abanico aluvial del río Colorado con el objetivo principal de comprender el rol de la tectónica, los cambios climáticos y eustáticos en la evolución del abanico aluvial. Este estudio es parte de un proyecto mayor que busca entender el origen de las lagunas someras presentes en la parte norte de la Patagonia. Nuestros resultados indican que el abanico aluvial del río Colorado se estableció en el área alrededor del Pleistoceno medio. La evidencia de deformaciones en las unidades del Mioceno al Pleistoceno indica una significativa actividad neotectónica durante el Pleistoceno superior. Para la transición Pleistoceno-Holoceno, el tectonismo generó una serie de terrazas. Posteriormente, un cambio climático de semiárido a árido favoreció la calcretización de las terrazas. Durante el Pleistoceno-Holoceno medio, las terrazas fueron cubiertas por la acumulación de sedimentos eólicos antiguos en condiciones de clima seco. En el Pleistoceno medio se desarrolló un amplio abanico aluvial en la región, en un clima más cálido y húmedo, que generó los depósitos aluviales del río Colorado-III en un nuevo nivel de terraza (T3). En el Holoceno tardío, el proceso de agradación fue favorecido por un alto nivel del mar y un clima templado-árido, que produjo la terraza T4. Al mismo tiempo, estas condiciones climáticas favorecieron los procesos de deflación-sedimentación local que dieron lugar a la deposición de depósitos eólicos modernos (mE) sobre la terraza T3. Las depresiones generadas por la deflación fueron, más tarde, ocupadas por los lagos poco profundos cuando el clima se volvió más húmedo. Posteriormente, durante condiciones regresivas del nivel del mar, ca. 2000 años AP, la terraza T4 fue parcialmente erosionada y se formó la llanura aluvial moderna.Fil: Seitz, Carina. Universidad Nacional del Sur. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Vélez, María I.. University Of Regina; CanadáFil: Perillo, Gerardo Miguel E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Nacional del Sur. Departamento de Geología; Argentin

Word-decoding as a function of temporal processing in the visual system.

This study explored the relation between visual processing and word-decoding ability in a normal reading population. Forty participants were recruited at Arizona State University. Flicker fusion thresholds were assessed with an optical chopper using the method of limits by a 1-deg diameter green (543 nm) test field. Word decoding was measured using reading-word and nonsense-word decoding tests. A non-linguistic decoding measure was obtained using a computer program that consisted of Landolt C targets randomly presented in four cardinal orientations, at 3-radial distances from a focus point, for eight compass points, in a circular pattern. Participants responded by pressing the arrow key on the keyboard that matched the direction the target was facing. The results show a strong correlation between critical flicker fusion thresholds and scores on the reading-word, nonsense-word, and non-linguistic decoding measures. The data suggests that the functional elements of the visual system involved with temporal modulation and spatial processing may affect the ease with which people read

Double lenses

The analysis of the shear induced by a single cluster on the images of a large number of background galaxies is all centered around the curl-free character of a well-known vector field that can be derived from the data. Such basic property breaks down when the source galaxies happen to be observed through two clusters at different redshifts, partially aligned along the line of sight. In this paper we address the study of double lenses and obtain five main results. (i) First we generalize the procedure to extract the available information, contained in the observed shear field, from the case of a single lens to that of a double lens. (ii) Then we evaluate the possibility of detecting the signature of double lensing given the known properties of the distribution of clusters of galaxies. (iii) As a different astrophysical application, we demonstrate how the method can be used to detect the presence of a dark cluster that might happen to be partially aligned with a bright cluster studied in terms of statistical lensing. (iv) In addition, we show that the redshift distribution of the source galaxies, which in principle might also contribute to break the curl-free character of the shear field, actually produces systematic effects typically two orders of magnitude smaller than the double lensing effects we are focusing on. (v) Remarkably, a discussion of relevant contributions to the noise of the shear measurement has brought up an intrinsic limitation of weak lensing analyses, since one specific contribution, associated with the presence of a non-vanishing two-galaxy correlation function, turns out not to decrease with the density of source galaxies (and thus with the depth of the observations).Comment: 40 pages, 15 figures. Accepted for publication in ApJ main journa

The hyaluronan-binding serine protease from human plasma cleaves HMW and LMW kininogen and releases bradykinin

The influence of the hyaluronanbinding protease (PHBSP), a plasma enzyme with FVII- and pro-urokinase-activating potency, on components of the contact phase (kallikrein/kinin) system was investigated. No activation or cleavage of the proenzymes involved in the contact phase system was observed. The procofactor high molecular weight kininogen (HK), however, was cleaved in vitro by PHBSP in the absence of any charged surface, releasing the activated cofactor and the vasoactive nonapeptide bradykinin. Glycosoaminoglycans strongly enhanced the reaction. The cleavage was comparable to that of plasma kallikrein, but clearly different from that of coagulation factor FXIa. Upon extended incubation with PHBSP, the light chain was further processed, partially removing about 60 amino acid residues from the Nterminus of domain D5 of the light chain. These cleavage site(s) were distinct from plasma kallikrein or FXIa cleavage sites. PHBSP and, more interestingly, also plasma kallikrein could cleave low molecular weight kininogen in vitro, indicating that domains D5(H) and D6(H) are no prerequisite for kininogen cleavage. PHBSP was also able to release bradykinin from HK in plasma where the pro-cofactor circulates predominantly in complex with plasma kallikrein or FXI. In conclusion, PHBSP represents a novel kininogen-cleaving and bradykinin-releasing enzyme in plasma that shares significant catalytic similarities with plasma kallikrein. Since they are structurally unrelated in their heavy chains (propeptide), their similar in vivo catalytic activities might be directed at distinct sites where PHBSP could induce processes that are related to the kallikrein/kinin system

Letter from E. A. Seitz

Letter concerning a copy of the catalogue for Utah Agricultural College

Report of the Management Advisory Services Division to the AICPA Council Meeting, Denver, Colorado, September 30, 1972

https://egrove.olemiss.edu/aicpa_assoc/1962/thumbnail.jp

MAS: An Expanded Program, Before the Spring Meeting of Council, May 10, 1971

https://egrove.olemiss.edu/aicpa_assoc/2026/thumbnail.jp

Gravitational deflection of light and helicity asymmetry

The helicity modification of light polarization which is induced by the gravitational deflection from a classical heavy rotating body, like a star or a planet, is considered. The expression of the helicity asymmetry is derived; this asymmetry signals the gravitationally induced spin transfer from the rotating body to the scattered photons.Comment: 6 pages, 1 figur