Correlation of structural lineaments and fracture traces to water-well yields in the Edwards Aquifer, Central Texas

Lineaments are "straight lines visible from afar on the surface of the earth". In the Austin, Texas area, lineaments reflect the structural grain of the Balcones-Ouachita fault zone and may indicate subsurface geologic phenomena such as faults, fractures, and joints. These structural features often represent discrete zones of high permeability, and thus, areas of enhanced flow of groundwater capable of transmitting greater quantities of water than surrounding, non-fractured, rock. For this study more than 900 lineaments and fracture traces, identified in aerial photographs during a previous study, were detected in the Barton Springs section of the Edwards Aquifer. The endpoints of each linear feature were digitized and tagged with a unique identification label. Rose plots, Cartesian histograms, and a series of statistical operations were utilized to illustrate regional trends in the orientation of lineaments. As an indicator of well productivity, specific capacities of 27 wells in the area were obtained. Sixty-one water samples were collected and analyzed to test for possible chemical evidence of lineament-well interactions. The orientations of lineaments and fracture traces in the study area clearly display a bimodal distribution with a primary trend of N 40 E and a secondary peak of N 50 W. A general correlation exists between increased well productivity and decreased distances to the nearest lineament, particularly within 200 feet of lineaments. Also, 10 of the 13 largest specific-capacity values are from wells located southeast of southwest-northeast trending lineaments. Nonparametric statistical methods show that direction from lineaments is a significant factor in predicting water-well yields. Lineaments provide a tool for predicting possible sites of environmental sensitivity with respect to groundwater resources. Examples include the siting of groundwater monitoring wells for point sources of pollution, predicting the likely underground flow paths of a pollution plume or locating dam sites for recharge enhancement. Awareness of the location, orientation, and density of structural lineaments will allow the water-resource manager to identify discrete groundwater flow paths, and, thus, predict contaminant plume migration.Geological Science

Carbohydrates as enantioinduction components in stereoselective catalysis

Carbohydrate derivatives are readily available chiral molecules, yet they are infrequently employed as enantioinduction components in stereoselective catalysis. In this review, synthetic approaches to carbohydrate-based ligands and catalysts are outlined, along with example applications in enantioselective catalysis. A wide range of carbohydrate-based functionality is covered, and key trends and future opportunities are identified

How experts and novices judge other peoples knowledgeability from language use.

How accurate are people in judging someone elses knowledge based on their language use, and do more knowledgeable people use different cues to make these judgments? We address this by recruiting a group of participants (informants) to answer general knowledge questions and describe various images belonging to different categories (e.g., cartoons, basketball). A second group of participants (evaluators) also answer general knowledge questions and decide who is more knowledgeable within pairs of informants, based on these descriptions. Evaluators perform above chance at identifying the most knowledgeable informants (65% with only one description available). The less knowledgeable evaluators base their decisions on the number of specific statements, regardless of whether the statements are true or false. The more knowledgeable evaluators treat true and false statements differently and penalize the knowledge they attribute to informants who produce specific yet false statements. Our findings demonstrate the power of a few words when assessing others knowledge and have implications for how misinformation is processed differently between experts and novices

The imprints of primordial non-gaussianities on large-scale structure: scale dependent bias and abundance of virialized objects

We study the effect of primordial nongaussianity on large-scale structure, focusing upon the most massive virialized objects. Using analytic arguments and N-body simulations, we calculate the mass function and clustering of dark matter halos across a range of redshifts and levels of nongaussianity. We propose a simple fitting function for the mass function valid across the entire range of our simulations. We find pronounced effects of nongaussianity on the clustering of dark matter halos, leading to strongly scale-dependent bias. This suggests that the large-scale clustering of rare objects may provide a sensitive probe of primordial nongaussianity. We very roughly estimate that upcoming surveys can constrain nongaussianity at the level |fNL| <~ 10, competitive with forecasted constraints from the microwave background.Comment: 16 pages, color figures, revtex4. v2: added references and an equation. submitted to PRD. v3: simplified derivation, additional reference

Conedy: a scientific tool to investigate Complex Network Dynamics

We present Conedy, a performant scientific tool to numerically investigate dynamics on complex networks. Conedy allows to create networks and provides automatic code generation and compilation to ensure performant treatment of arbitrary node dynamics. Conedy can be interfaced via an internal script interpreter or via a Python module

Stereoselective synthesis of glycosides using (salen)Co catalysts as promoters

The use of (salen)Co catalysts as a new class of bench-stable stereoselective glycosylation promoters of trichloroacetimidate glycosyl donors at room temperature is described.</p

Occultation of the Quiescent Emission from Sgr A* by IR Flares

We have investigated the nature of flare emission from Sgr A* during multi-wavelength observations of this source that took place in 2004, 2005 and 2006. We present evidence for dimming of submm and radio flux during the peak of near-IR flares. This suggests that the variability of Sgr A* across its wavelength spectrum is phenomenologically related. The model explaining this new behavior of flare activity could be consistent with adiabatically cooling plasma blobs that are expanding but also partially eclipsing the background quiescent emission from Sgr A*. When a flare is launched, the plasma blob is most compact and is brightest in the optically thin regime whereas the emission in radio/submm wavelengths has a higher opacity. Absorption in the observed light curve of Sgr A* at radio/submm flux is due to the combined effects of lower brightness temperature of plasma blobs with respect to the quiescent brightness temperature and high opacity of plasma blobs. This implies that plasma blobs are mainly placed in the magnetosphere of a disk-like flow or further out in the flow. The depth of the absorption being larger in submm than in radio wavelengths implies that the intrinsic size of the quiescent emission increases with increasing wavelength which is consistent with previous size measurements of Sgr A*. Lastly, we believe that occultation of the quiescent emission of Sgr A* at radio/submm by IR flares can be used as a powerful tool to identify flare activity at its earliest phase of its evolution.Comment: 11 pages, 5 figures, accepted by ApJ