The architecture, growth and tectono-stratigraphic significance of rift-oblique lineaments on the NE Atlantic Margin

Fault domain boundaries are characteristic features of segmented rift systems and have been recreated in analogue models. Two end member conceptual models of fault domain boundaries currently exist. 1) Accommodation zones, which are broad regions of overlapping normal faults and which trend oblique to the rift axis. 2) Transfer zones, which are discrete sub-vertical fault systems that directly link en-echelon normal fault domains. These structures are commonly believed to segment natural rift systems on a variety of scales and impact directly upon the stratigraphic and magmatic evolution of a basin. The NE Atlantic Margin is a volcanic passive margin which has undergone a series of rift events culminating with continental breakup in the Early Cenozoic. From potential field, seismic reflection, seismic refraction and ocean bottom seismometer datasets, a series of rift-oblique lineaments (loosely referred to as ‘transfer zones’) have been identified which are commonly inferred to compartmentalise and laterally offset structural highs and depocentres developed within the Mesozoic – Cenozoic rift basins. A range of hypotheses are proposed to explain the origin of these lineaments, including fault domain boundaries, basin-wide strike-slip faults and other, non-tectonic origins. Using well-calibrated 2D and 3D seismic data, this study critically assesses the structural, stratigraphic and magmatic evidence for the rift-oblique lineaments in the Faroe-Shetland Basin and Vøring Basin, both located upon the NE Atlantic Margin. Results from the Faroe-Shetland Basin show structures previously attributed to basin-wide strike-slip deformation can be more simply explained as igneous intrusions, hydrothermal vent complexes, gas chimneys and/or faults that transfer extensional strain between en-echelon rift segments (i.e. fault domain boundaries). There is little evidence to suggest that activity along a series of discrete, basin-wide lineaments controlled Paleocene sedimentation in the basin. In the northern Vøring Basin, a previously identified fault domain boundary (the Rym Accommodation Zone) is analysed to understand if, and how strain is transferred between two adjacent fault domains. The results of this study highlight major differences between the offset rift segments in view of the style of rifting, timing, the loci of faulting, the relative uplift and subsidence histories as well as the impact of variations in the deep crustal structure. Analyses reveal that strain is not fully transferred across the fault domain boundary, with significant variation in beta factors calculated for each rift segment. The structural style within the Rym Accommodation Zone is complex, with the rotation of normal fault orientations, major relay ramp formation and rift perpendicular normal oblique faulting observed, elements that are not present in most existing conceptual models of accommodation zones. The results also imply that transfer zones may be an integral part of a larger accommodation zone rather than an opposite end member as previously believed. In the final aspect of the study, a second rift-oblique lineament is analysed in the northern Vøring Basin: the Gleipne Lineament. Results highlight the close structural relationship between the Gleipne Lineament and underlying basement structure, with the lineament acting as a conduit for sediment to enter the Vøring Basin during phases of rifting. Under periods of minimal upper crustal deformation, the lineament exerted a lesser control upon basinal sedimentation. The Rym Accommodation Zone in contrast did not source sediment into the Vøring Basin, instead, it compartmentalised the basin during rifting which increased the complexity of the predicted basin fill. Increased Late Paleocene intrusive and extrusive igneous deposits are observed along the strike of both lineaments but are not directly linked to active tectonic deformation. In conclusion, rift-oblique lineaments are unlikely to be basin-wide features and each appears to be unique in its structural style and geological origin. In turn, this means that different lineaments are likely to have different impacts upon the stratigraphical and magmatic development of a basin. Previous inferences that basin-wide lineaments have controlled sediment entry and transport within rift basins on the NE Atlantic Margin need to be substantiated on a case-by-case basis. The results of this study are further considered and discussed to predict the nature of rift-segmenting structures in the sub-basalt region of the Faroe-Shetland Basin, which is poorly resolved by current 2D and 3D seismic imaging

Lying Your Way to Better Traffic Engineering

To optimize the flow of traffic in IP networks, operators do traffic engineering (TE), i.e., tune routing-protocol parameters in response to traffic demands. TE in IP networks typically involves configuring static link weights and splitting traffic between the resulting shortest-paths via the Equal-Cost-MultiPath (ECMP) mechanism. Unfortunately, ECMP is a notoriously cumbersome and indirect means for optimizing traffic flow, often leading to poor network performance. Also, obtaining accurate knowledge of traffic demands as the input to TE is elusive, and traffic conditions can be highly variable, further complicating TE. We leverage recently proposed schemes for increasing ECMP's expressiveness via carefully disseminated bogus information ("lies") to design COYOTE, a readily deployable TE scheme for robust and efficient network utilization. COYOTE leverages new algorithmic ideas to configure (static) traffic splitting ratios that are optimized with respect to all (even adversarially chosen) traffic scenarios within the operator's "uncertainty bounds". Our experimental analyses show that COYOTE significantly outperforms today's prevalent TE schemes in a manner that is robust to traffic uncertainty and variation. We discuss experiments with a prototype implementation of COYOTE

Gallium(III)-Promoted Halocyclizations of 1,6-Diynes

Adrian Landreth was an REU student, summer 2014Cyclization of 1,6-diynes promoted by stoichiometric Ga(III) halides produces vinyl halides in good to excellent yields. Under acidic conditions, initially formed iodocyclization products undergo in situ Friedel-Crafts cyclizations, giving access to iodo-indenopyridines. The application of the vinyl halides in cross-coupling reactions has been explored, and mechanistic aspects of the cyclization are discussed.HIGMS CMLD Initiative (P50 GM067041) NSF REU - Adrian Landreth support (CHE 1156666) NSF - NMR purchase (CHE 0619339) NSF - HRMS purchase (CHE0443618

Using hierarchical clustering methods to classify motor activities of COPD patients from wearable sensor data

BACKGROUND: Advances in miniature sensor technology have led to the development of wearable systems that allow one to monitor motor activities in the field. A variety of classifiers have been proposed in the past, but little has been done toward developing systematic approaches to assess the feasibility of discriminating the motor tasks of interest and to guide the choice of the classifier architecture. METHODS: A technique is introduced to address this problem according to a hierarchical framework and its use is demonstrated for the application of detecting motor activities in patients with chronic obstructive pulmonary disease (COPD) undergoing pulmonary rehabilitation. Accelerometers were used to collect data for 10 different classes of activity. Features were extracted to capture essential properties of the data set and reduce the dimensionality of the problem at hand. Cluster measures were utilized to find natural groupings in the data set and then construct a hierarchy of the relationships between clusters to guide the process of merging clusters that are too similar to distinguish reliably. It provides a means to assess whether the benefits of merging for performance of a classifier outweigh the loss of resolution incurred through merging. RESULTS: Analysis of the COPD data set demonstrated that motor tasks related to ambulation can be reliably discriminated from tasks performed in a seated position with the legs in motion or stationary using two features derived from one accelerometer. Classifying motor tasks within the category of activities related to ambulation requires more advanced techniques. While in certain cases all the tasks could be accurately classified, in others merging clusters associated with different motor tasks was necessary. When merging clusters, it was found that the proposed method could lead to more than 12% improvement in classifier accuracy while retaining resolution of 4 tasks. CONCLUSION: Hierarchical clustering methods are relevant to developing classifiers of motor activities from data recorded using wearable systems. They allow users to assess feasibility of a classification problem and choose architectures that maximize accuracy. By relying on this approach, the clinical importance of discriminating motor tasks can be easily taken into consideration while designing the classifier

The steady state quantum statistics of a non-Markovian atom laser

We present a fully quantum mechanical treatment of a single-mode atomic cavity with a pumping mechanism and an output coupling to a continuum of external modes. This system is a schematic description of an atom laser. In the dilute limit where atom-atom interactions are negligible, we have been able to solve this model without making the Born and Markov approximations. When coupling into free space, it is shown that for reasonable parameters there is a bound state which does not disperse, which means that there is no steady state. This bound state does not exist when gravity is included, and in that case the system reaches a steady state. We develop equations of motion for the two-time correlation in the presence of pumping and gravity in the output modes. We then calculate the steady-state output energy flux from the laser.Comment: 14 pages (twocloumn), 6 figure

Legendrean and G2 Contact Structures

We investigate two parabolic contact geometries: Legendrean contact structures and G2 contact structures. The methods used are mostly independent of the general theory of parabolic geometry. Building on the work of Eastwood and Nurowski we present a new method of generating G2 contact structures from five-dimensional Legendrean contact structures. This construction requires some input data, a choice of sections, and we calculate the minimal partial torsion, the obstruction to flatness of the G2 contact geometry, in terms of this input data. We show that in fact every G2 contact structure arises (locally) via this construction. Separately, inspired by the prolongation of the conformal-to-Einstein equation, we construct the standard tractor bundle for five-dimensional integrable Legendrean contact structures via prolongation of an invariantly defined partial di↵erential equation. We compute the partial curvature of the invariant partial connection on this bundle and show, by constructing an explicit isomorphism, that the geometry is locally isomorphic to the homogeneous model if and only if the partial curvature vanishes. We outline a similar prolongation procedure for G2 contact structures. There is a detailed review of relevant facts about contact manifolds, including the construction of the Rumin complex. We work out the required theory of partial connections on contact manifolds. We explain how to write many of the natural di↵erential operators on a contact manifold, for example, the Rumin complex, in terms of a suitably adapted partial connection.Thesis MPhil) -- University of Adelaide, School of Mathematical Sciences, 202

Glacial flour dust storms in the Gulf of Alaska : hydrologic and meteorological controls and their importance as a source of bioavailable iron

Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 38 (2011): L06602, doi:10.1029/2010GL046573.Iron is an essential micronutrient that limits primary productivity in much of the ocean, including the Gulf of Alaska (GoA). However, the processes that transport iron to the ocean surface are poorly quantified. We combine satellite and meteorological data to provide the first description of widespread dust transport from coastal Alaska into the GoA. Dust is frequently transported from glacially-derived sediment at the mouths of several rivers, the most prominent of which is the Copper River. These dust events occur most frequently in autumn, when coastal river levels are low and riverbed sediments are exposed. The dust plumes are transported several hundred kilometers beyond the continental shelf into iron-limited waters. We estimate the mass of dust transported from the Copper River valley during one 2006 dust event to be between 25–80 ktons. Based on conservative estimates, this equates to a soluble iron loading of 30–200 tons. We suggest the soluble Fe flux from dust originating in glaciofluvial sediment deposits from the entire GoA coastline is two to three times larger, and is comparable to the annual Fe flux to GoA surface waters from eddies of coastal origin. Given that glaciers are retreating in the coastal GoA region and in other locations, it is important to examine whether fluxes of dust are increasing from glacierized landscapes to the ocean, and to assess the impact of associated Fe on marine ecosystems.We appreciate support from the USGS CMGP, NCCWSC, the Mendenhall postdoc program, the Woods Hole PEP intern program, and from NASA‐IDS

Resonance fluorescence in a band gap material: Direct numerical simulation of non-Markovian evolution

A numerical method of calculating the non-Markovian evolution of a driven atom radiating into a structured continuum is developed. The formal solution for the atomic reduced density matrix is written as a Markovian algorithm by introducing a set of additional, virtual density matrices which follow, to the level of approximation of the algorithm, all the possible trajectories of the photons in the electromagnetic field. The technique is perturbative in the sense that more virtual density matrices are required as the product of the effective memory time and the effective coupling strength become larger. The number of density matrices required is given by $3^{M}$ where $M$ is the number of timesteps per memory time. The technique is applied to the problem of a driven two-level atom radiating close to a photonic band gap and the steady-state correlation function of the atom is calculated.Comment: 14 pages, 9 figure

Management of pediatric radiation dose using GE fluoroscopic equipment

In this article, we present GE Healthcare’s design philosophy and implementation of X-ray imaging systems with dose management for pediatric patients, as embodied in its current radiography and fluoroscopy and interventional cardiovascular X-ray product offerings. First, we present a basic framework of image quality and dose in the context of a cost–benefit trade-off, with the development of the concept of imaging dose efficiency. A set of key metrics of image quality and dose efficiency is presented, including X-ray source efficiency, detector quantum efficiency (DQE), detector dynamic range, and temporal response, with an explanation of the clinical relevance of each. Second, we present design methods for automatically selecting optimal X-ray technique parameters (kVp, mA, pulse width, and spectral filtration) in real time for various clinical applications. These methods are based on an optimization scheme where patient skin dose is minimized for a target desired image contrast-to-noise ratio. Operator display of skin dose and Dose-Area Product (DAP) is covered, as well. Third, system controls and predefined protocols available to the operator are explained in the context of dose management and the need to meet varying clinical procedure imaging demands. For example, fluoroscopic dose rate is adjustable over a range of 20:1 to adapt to different procedure requirements. Fourth, we discuss the impact of image processing techniques upon dose minimization. In particular, two such techniques, dynamic range compression through adaptive multiband spectral filtering and fluoroscopic noise reduction, are explored in some detail. Fifth, we review a list of system dose-reduction features, including automatic spectral filtration, virtual collimation, variable-rate pulsed fluoroscopic, grid and no-grid techniques, and fluoroscopic loop replay with store. In addition, we describe a new feature that automatically minimizes the patient-to-detector distance, along with an estimate of its dose reduction potential. Finally, two recently developed imaging techniques and their potential effect on dose utilization are discussed. Specifically, we discuss the dose benefits of rotational angiography and low frame rate imaging with advanced image processing in lieu of higher-dose digital subtraction

Atypical knemidokoptosis in two Dunnocks (Prunella modularis) in southern England

Avian knemidokoptosis, caused by knemidokoptid mites (Knemidokoptinae: Epidermoptidae), has been reported in wild and domestic birds globally. We report two cases of severe knemidokoptosis in Dunnocks (Prunella modularis) from separate sites in Great Britain, where the disease has previously been reported predominantly in finches and, less frequently, in corvids