Sedimentation study, Environmental Monitoring and Operations Guidance System (EMOGS), Kings Bay, Georgia and Florida, 1988-1990 : final report

Repeated side-scan sonar and multi-frequency bathymetric surveys, accompanied by accurate, high resolution, and repeatable navigation, were conducted in the vicinity of a tidal inlet to define the length and time scales associated with bedforms and channel shoaling in a structured tidal inlet. The study site, St. Marys entrance channel along the Georgia/Florida border (Fig. 1), has a dredged channel approximately 46-52 feet in depth at a datum of mean low water (MLW), bordered by a large ebb tidal delta. The tidal inlet serves Cumberland Sound, Kings Bay, and associated waterways, providing a large discharge of water from the inlet that creates bedforms and channel shoaling, given the abundance of sand-size sediment in the vicinity. The jettied inlet produces flows that are predominantly tidally-driven, whereas farther offshore the driving forces consist predominantly of waves and storm-generated flows. In the channel reaches (Table 1) between these two areas, combined wave/steady flows are present, creating a myriad of scales of bedforms and shoaling patterns, emphasizing the difference in these scales between the three different flow regimes. The results provide an important data base for quantifying shoaling processes and mechanisms in tidal inlet channels.Funding was provided by the National Oceanic & Atmospheric Administration's Sea Grant Program through Grant NA860-A-D-090

Sedimentation study, Environmental Monitoring and Operations Guidance System (EMOGS), Kings Bay, Georgia and Florida : Phase III--FY 1989

Repeated side-scan sonar and multi-frequency bathymetric surveys, accompanied by accurate, high resolution, and repeatable navigation, were conducted in the vicinity of a tidal inlet to define the length and time scales associated with bedforms and channel shoaling in a structured tidal inlet. The study site, St. Mary's entrance channel along the Georgia/Florida border (Fig. I), has a dredged channel approximately 46-52 feet in depth, bordered by a large ebb tidal delta. The tidal inlet serves Cumberland Sound, Kings Bay, and associated waterways, providing a large discharge of water from the inlet that creates bedforms and channel shoaling, given the abundance of sand-sized sediment in the vicinity. The jettied inlet produces flows tht are predominately tidally-driven, whereas farther offshore the driving forces consist predominately of waves and storm-generated flows. In the channel reaches (Table 1) between these two areas, combined wave-steady flows are present, creating a myriad of scales of bedforms and shoaling patterns. This study was designed to elucidate the time and space scales of these variable bedforms and shoaling patterns, emphasizing the difference in these scales between the three different flow regimes. The results provide an important data base for quantifying shoaling processes and mechanisms in tidal inlet channels.Funding was provided by the National Oceanic Atmospheric Administration under Sea Grant No. NA860A-D-SG090

Mirizzi syndrome associated with hepatic artery pseudoaneurysm: a case report.

INTRODUCTION: This is the first case report of Mirizzi syndrome associated with hepatic artery pseudoaneurysm. CASE PRESENTATION: A 54-year-old man presented with painful obstructive jaundice and weight loss. Computed tomography showed a hilar mass in the liver. Following an episode of haemobilia, angiography demonstrated a pseudoaneurysm of a branch of the right hepatic artery that was embolised. At surgery, a gallstone causing Mirizzi type II syndrome was found to be responsible for the biliary obstruction and a necrotic inflammatory mass and haematoma were found to be extending into the liver. The mass was debrided and drained, the obstructing stones removed and the bile duct drained with a t-tube. The patient made a full recovery. CONCLUSION: This case highlights another situation where there may be difficulty in differentiating Mirizzi syndrome from biliary tract cancer.Published versio

Effect of Floodplain Obstructions on the Discharge Conveyance Capacity of Compound Channels

: Results of an experimental study into steady uniform flows in compound open channels with cylindrical obstructions designed to mimic emergent vegetation is presented. Two configurations—fully covered floodplain and one-line obstructions—are considered, and the hydraulic properties are compared to those of a smooth, unobstructed compound channel. Particular attention is given to the effect of obstruction (i.e., vegetation) density on the rating curve, drag coefficients, and spanwise profiles of streamwise velocity. Flow resistance is estimated using an established approach, and the results are in agreement with other experimental studies. It was shown that the obstruction configuration significantly influences the flow velocity in the main channel, and in the case of one-line obstructions the floodplain velocity is higher than for an unobstructed channel for a given flow rate. Spanwise velocity profiles exhibit markedly different characters in the one-line and fully covered configurations

“Just Imagine That…”: A Solution Focused Approach to Doctoral Research Supervision in Health and Social Care

Effective supervision in doctoral research is critical to successful and timely completion. However,supervision is a complex undertaking with structural as well as relational challenges for bothstudents and supervisors. This instructional paper describes an internationally applicable approach tosupervision that we have developed in the health and social care disciplines that offers structure, butis also dynamic and responsive to the needs of students and supervisors and aims to develop theresearch competency of students. Our approach called Solution Focused Research Supervision(SFRS) is based on solution focused approaches, adapted from Solution Focused Brief Therapy andquestioning techniques derived from coaching. This approach has enabled our supervision teams toeffectively develop focused research questions and decide on appropriate research methodologiesand methods. We offer the SFRS approach as a way of working that seeks to recognize and buildupon strengths, foster engagement and openness to learning as well as build trust between studentsand supervisors. The authors, from (countries deleted for peer review), are supervisors and studentswho have developed the approach and provide practical examples of its application

LINVIEW: Incremental View Maintenance for Complex Analytical Queries

Many analytics tasks and machine learning problems can be naturally expressed by iterative linear algebra programs. In this paper, we study the incremental view maintenance problem for such complex analytical queries. We develop a framework, called LINVIEW, for capturing deltas of linear algebra programs and understanding their computational cost. Linear algebra operations tend to cause an avalanche effect where even very local changes to the input matrices spread out and infect all of the intermediate results and the final view, causing incremental view maintenance to lose its performance benefit over re-evaluation. We develop techniques based on matrix factorizations to contain such epidemics of change. As a consequence, our techniques make incremental view maintenance of linear algebra practical and usually substantially cheaper than re-evaluation. We show, both analytically and experimentally, the usefulness of these techniques when applied to standard analytics tasks. Our evaluation demonstrates the efficiency of LINVIEW in generating parallel incremental programs that outperform re-evaluation techniques by more than an order of magnitude.Comment: 14 pages, SIGMO

Fast matrix computations for pair-wise and column-wise commute times and Katz scores

We first explore methods for approximating the commute time and Katz score between a pair of nodes. These methods are based on the approach of matrices, moments, and quadrature developed in the numerical linear algebra community. They rely on the Lanczos process and provide upper and lower bounds on an estimate of the pair-wise scores. We also explore methods to approximate the commute times and Katz scores from a node to all other nodes in the graph. Here, our approach for the commute times is based on a variation of the conjugate gradient algorithm, and it provides an estimate of all the diagonals of the inverse of a matrix. Our technique for the Katz scores is based on exploiting an empirical localization property of the Katz matrix. We adopt algorithms used for personalized PageRank computing to these Katz scores and theoretically show that this approach is convergent. We evaluate these methods on 17 real world graphs ranging in size from 1000 to 1,000,000 nodes. Our results show that our pair-wise commute time method and column-wise Katz algorithm both have attractive theoretical properties and empirical performance.Comment: 35 pages, journal version of http://dx.doi.org/10.1007/978-3-642-18009-5_13 which has been submitted for publication. Please see http://www.cs.purdue.edu/homes/dgleich/publications/2011/codes/fast-katz/ for supplemental code

Hydroblack 91 : report of the CTD Intercalibration Workshop

An Intercalibration Workshop was held at the Woods Hole Oceanographic Institution (W.H.O.I.) from 1-10 December, 1991, for the CTD data acquired during HYDROBLACK '91. This intercalibration exercise was a prelude to an interdisciplinary HYDROBLACK '91 intercalibration to be held in Crimea, Ukraine, in February, 1992, incorporating the full suite of physical, biological, and chemical measurements acquired during the cruise. HYDROBLACK '91 acquired for the first time a complete hydrographic, biological, and chemical data set for the entire Black Sea, to 200 m water depth, with the participation of all Black Sea riparian countres as well as the U.S. Nearly 300 hydrographic stations were occupied to full water depth; biological and chemical measurements were made at 100 of these stations. This quasi-synoptic survey was accomplished using five ships during an interval of approximately three weeks. Results show some disparities between CTD's from the different regions, but the intercalibrated results show a consistent and high resolution detail of the dynamic topography and other physical characteristics of the entire Black Sea basin. The intercalibrated data set is now available within each country and from W.H.O.I., and will form the basis for studies on ocean physics as well as interdisciplinary issues such as oxygen depletion within the basin and hydrogen sulfide distribution. This effort provides an intercalibrated, spatially-dense baseline against which all future and past measurements can be compared. In spite of significant economic pressures arising from the changes in the eastern European countries, and the inadequate scientific exchange with the west during the past two decades, HYDROBLACK '91 is considered a success and a model for future international scientific and monitoring efforts thoughout the Black Sea. Similar efforts are anticipated twice-yearly in the framework of the new Cooperative Marine Science Program for the Black Sea.Funding was provided by the National Science Foundation through Grant No. OCE-9121788, the Vetleson Foundation, the Andrew W. Mellon Foundation, the Mobil Foundation, Inc. and the Regional Environmental Center for Central & Eastern Europe (Budapest)

Free Surface Flow Over Square Bars at Intermediate Relative Submergence

Results from large-eddy simulations and complementary flume experiments of turbulent open channel flows over bed-mounted square bars at intermediate submergence are presented. Scenarios with two bar spacings, corresponding to transitional and k-type roughness, and three flow rates, are investigated. Good agreement is observed between the simulations and the experiments in terms of mean free surface elevations and mean streamwise velocities. Contours of simulated time-averaged streamwise, streamfunction and turbulent kinetic energy are presented and these reveal the effect of the roughness geometry on the water surface response. The analysis of the vertical distribution of the streamwise velocity shows that in the lowest submergence cases no logarithmic layer is present, whereas in the higher submergence cases some evidence of such a layer is observed. For several of the flows moderate to significant water surface deformations are observed, including weak and/or undular hydraulic jumps which affect significantly to the overall streamwise momentum balance. Reynolds shear stress, form-induced stress and form drag are analysed with reference to the momentum balance to assess their contributions to the total hydraulic resistance of these flows. The results show that form-induced stresses are dominant at the water surface and can contribute significantly to the overall drag, but the total resistance in all cases is dominated by form drag due to the presence of the bars