bluuebunny/crossref_metadata_2025 huggingface dataset:
Waste to Energy Strategy and Approach for Ireland
Authors: Reynolds Anthony , LeGoy Philip R. , Sweeney Aidan
Published: January 2009

Waste to Energy (WTE) is a viable and vital resource to Ireland. Due to its geographic location, strategically located between the U.S. and Europe, Ireland has inherent advantages when it comes to gaining technical knowledge. As an island country with its size it has exaggerated waste elimination problems. Power generation in Ireland is distorted by the size of the island and Irelands recent high-tech business boom has had an affect too. These two items, power and waste, overlap and can be addressed (in part) with one solution. Products not produced in Ireland are imported. The residue of these products is garbage. Therefore the garbage is constantly being imported to the island and never expelled. Landfill space in Ireland is diminishing — rapidly. “Not in my backyard!” is a principal attitude of the public and with good reason. Refuse is a health threat. Landfill tax legislation is changing and the price is rising to €19/tonne and heading for €32/tonne. Converting waste to energy as part of a recycling process garnishes public support because the resource of rubbish is managed in a manner that appeals to common sense. It is a solution that takes into account the public health and providence of the island. If waste is sorted and classified as economically recyclable (i.e. marketable) it is reclaimed and reused. If waste is sorted and classified as economically un-recyclable by conventional methods it is then evaluated for its energy value in power generation and thermal conversion to basic elemental products. The classification process determines the value of waste products, therefore the economic implications of their use either by recycling the waste and thermally eliminating it while generating electricity and/or by producing recycled products. This paper presents a waste recycling/generation project concept that includes waste stream separation, refuse-derived fuels, waste gasification/generation and renewable power resource integration.
Tipping Floor Safety at American Ref-Fuel
Authors: Skiba Mark , Stanton Raymond
Published: January 2009

Across the industry the tipping floor is considered to be one of the most hazardous areas of the facility. Just the fact that there may be twenty different waste hauling drivers with their own agenda in one area can lead to potential hazards. Across the industry there have been driver deaths that have occurred due to the drivers wandering away from their trucks or reentering the floor without notifying the tipping floor attendants.
Non Linear Seismic Pile Soil Structure Interaction Analysis of Piles in Offshore Platforms
Authors: Kimiaei Mehrdad , Shayanfar Mohsen Ali , El Naggar M. Hesham , Aghakouchak Ali Akbar
Published: January 2009

Pile supported offshore platforms in seismically active areas should be designed to survive severe earthquake excitations with no global structural failure. It is often required to perform nonlinear seismic analysis of offshore platforms that accounts for soil nonlinearity, discontinuity condition at pile soil interfaces, energy dissipation through soil radiation damping and structural nonlinear behaviours of the piles. In this study a BNWF (Beam on Nonlinear Winkler Foundation) model is incorporated into a finite element program (ANSYS) and it is used to compute the lateral response of piles subjected to seismic loading. The soil stiffness is established using the P-Y curve. The results of equivalent linear earthquake free field ground motion analyses are used as the input excitations at support nodes of the model. The components and advantages of this practical ANSYS model in seismic pile soil structure interaction analyses are discussed and addressed in detail. Computed responses compared well with the experimental test results. Sensitivity of the results to model parameters and site response calculations are evaluated.
Risk Based Inspection and Repair Optimization of Ship Structures Considering Corrosion Effects
Authors: Li Dianqing , Zhang Shengkun , Tang Wenyong
Published: January 2009

A theoretical framework of risk based optimal inspection and repair planning is proposed for the ship structures subjected to corrosion deterioration. The planning problem is formulated as an optimization problem where the expected lifetime costs were minimized with a constraint on the minimum acceptable reliability index. The safety margins are established for the inspection events, the repair events and the failure events for ship structures. Moreover, the formulae are derived to calculate failure probabilities and repair probabilities. Based on them, a component subjected to pitting corrosion is investigated to illustrate the process of selecting the optimal inspection and repair strategy. Furthermore, some sensitivity studies were provided. The results show that the optimal inspection instants should take place before the reliability index reaches the minimum acceptable reliability index. The optimal target failure probability is 10−3. In addition, a balance can be achieved between the risk cost and total expected inspection and repair costs by using the risk based optimal inspection and repair method, which is very effective in selecting the optimal inspection and repair strategy.
Explosion Recurrence Modelling
Authors: Yasseri Sirous F. , Prager Jake
Published: January 2009

This paper describes a recurrence law for explosions. The proposed recurrence law fits quite well to the historic explosion data in residential buildings as well as to the data on offshore installations in the North Sea. Generally quantified explosion risk assessment is performed for offshore installations, since it is believed historic data does not correspond to a specific installation and it may not be appropriate for use in performance based explosion engineering, which may in itself require realistic load description of explosion recurrence. The goodness-of-fit of the model for explosion occurrence data obtained using the quantified risk assessment method is also discussed. The paper then introduces the concept of performance-based design, which is an attempt to design structures with predictable performance under explosion loading. Performance objectives such as life safety, collapse prevention, or immediate resumption of operation are used to define the state of an installation following a design explosion. The recurrence law is then used to associate a level of explosion load to each limit state using a desirable level of probability of exceedance during the installations life time.
Vortex-Induced Vibration of Horizontal Circular Cylinder in Uniform Flow
Authors: Kokubun Kentaroh , Wada Yasuhiro
Published: January 2009

This paper treats Vortex-Induced Vibration (VIV) of a cylinder in uniform flow. The cylinder is aluminum, rigid, circular, and 0.490 m in length, 0.025 m in diameter, and its weight is counterbalanced by buoyancy. The cylinder is horizontally mounted in a two-dimensional tank and allowed to move vertically by hanging through a spring during towing. The equation of motion of the structure is described in the nonlinear form and an approximate solution of the equation is obtained by using a vibrational theory. Lock-in phenomena appear when the vortex shedding frequency approaches to the natural frequency of the structure. Experimental results show that the oscillation of structure has remarkable two frequencies corresponding to the shedding frequency and the natural frequency of the structure. By using amplitude of vertical displacement at the top peak frequency, this paper proposes a way of estimating the transverse force, i.e., lift coefficient during VIV. The estimated lift coefficients are similar to the measured lift coefficients with the vertical displacement restricted to be zero. The estimated lift coefficients seem to be feasible.
Bearing Behaviour of Spudcan Foundation on Uniform Clay During Deep Penetration
Authors: Hossain M. S. , Hu Y. , Randolph M. F.
Published: January 2009

In order to design a safe spudcan foundation, it is important to predict its bearing behaviour accurately based on the corresponding soil failure mechanisms. Thus, the performance of spudcan foundation, during deep penetration into uniform soil, is investigated physically and numerically. In physical testing, a series of centrifuge tests are carried out in a drum centrifuge. The half-spudcan model tests with subsequent Particle Image Velocimetry (PIV) analysis are conducted to reveal soil failure mechanisms during spudcan penetration. And the full spudcan model tests are conducted to investigate the bearing capacity of spudcan. In numerical simulation, FE analyses are performed considering smooth and rough soilspudcan interface. From the physical tests and numerical analyses, it is observed that the cavity is formed above the spudcan as it is penetrating into uniform clay. At certain penetration depths, the soil underneath the spudcan starts to flow back on top of the spudcan, which leads the spudcan to be embedded with further penetration. Soil flow mechanisms, at various penetration depths, play a key role in footing bearing response. And the ultimate undrained bearing capacity factor of Nc = 10.5 (smooth) and 12 (rough) are obtained at deep penetration.
Accurate Calculation of Confidence Intervals on Predicted Extreme Met-Ocean Conditions When Using Small Datasets
Authors: Brooker Daniel C. , Cole Geoffrey K.
Published: January 2009

Estimation of high return period values of wind and wave conditions is usually done using a limited sample of data from measurement or hindcast studies. Because a finite sample size is used, the reliability of estimates is usually evaluated by constructing confidence intervals around design values such as the 100 year return value. In this paper, a numerical simulation study is used to compare the accuracy of calculated confidence intervals using several different calculation methods: the asymptotic normal, parametric bootstrap and profile likelihood methods. The accuracy of each method for different sample sizes is assessed for the truncated Weibull distribution. Based on these results, a profile likelihood method for estimation of confidence intervals is suggested for use when dealing with small datasets.
A Wavelet Approach to Pipeline Leak Detection by Pressure Analysis
Authors: Gadelha de Freitas Ricardo Dantas , Maitelli Andre´ Laurindo , Salazar Andre´s Ortiz
Published: January 2009

One of the most challenging tasks in an oil field is implementation of a software-based leak detection system on a multi-phase flow pipeline. When a leak occurs in a multi-phase flow pipeline, the flow cannot be measured with accuracy. So, none of the various pipeline leak detection methodologies can offer good performance on a multi-phase flow pipeline. This paper will discuss implementation of a leak detection system in a particular oil field using state-of-the-art signal processing techniques to apply to the data collected in a oil pipeline. This leak detection system is still in development and uses a more practical approach to the problem than traditional methods and was implemented on a PC under the Windows operating system. Windowing, joint time-frequency analysis and wavelets were considered to develop methods of detecting leaks by watching for the wavefront. The idea behind these techniques is to cut the signal of interest into several parts and then analyze the parts separately. It is impossible to know the exact frequency and the exact time of occurrence of the leak frequency in a signal. In other words, a leak signal can simply not be represented as a point in the time-frequency space. It is very important how one cuts the signal to implement the analysis. The wavelet transform or wavelet analysis is probably the most recent solution to overcome the shortcomings of the Fourier transform. The wavelet transforms are used to perform atomic decompositions of the pressure signal that comes from a single point of a pipeline. A number of time-frequency decompositions are attempted. What is expected of this decomposition is that it fits the perceptible changes in the pressure and then an Artificial intelligent System (AIS) decides if the variations in the signal are inherent (common-cause variations) or external to the process (failed instrument, occurrence of a leak, causes that are not part of the process). The AIS learns about continual changes in the pipeline. This is useful as pipeline operation always changes and instrument drift could occur over a long time period.
Development of a New Method of Liquid CO2 Injection Into the Seawaters for the Ocean Sequestration
Authors: Yamasaki Akihiro , Tajima Hideo , Kiyono Fumio , Teng Ho
Published: January 2009

A new type of injection method of liquid CO2 into the seawaters via a Kenics-type static mixer for the ocean sequestration of CO2 has been developed. Flows of liquid CO2 and water will form a two-phase flow in a pipeline, and introduced to a static mixer, where the two-phase flow is mixed by the agitation effects of the mixing elements equipped in the mixer, and converted into various flow patterns. The following flow patterns were observed depending on the flow velocities; dispersed flow of liquid CO2 drops, flow of CO2 hydrate agglomerates, and flow of CO2 hydrate particles. The results indicate that several options for CO2 injection concerning the form of CO2, size distribution of liquid CO2 drops, could be realized by using the present method. The choice of such options is essential to control the fate of the disposed CO2 and the consequent environmental impact. In this study, application of the present method to the disposal of liquid CO2 at the intermediate depths (500 ∼ 1500 m) is assumed. The formation of the liquid CO2 drops by the static mixer was studied experimentally, and the effect of the static mixer on the size distribution of the liquid CO2 drops was investigated. The mean size of the liquid CO2 drops were significantly reduced by using the static mixer, compared with the case without the mixer for a given flow velocity, and a sharper distribution of the drop size was obtained. Based on the experimental results, the ascending-dissolving fate of the liquid CO2 drops disposed of in the ocean at the intermediate depth was numerically simulated. The shaper distribution and smaller mean diameter of the liquid CO2 drops produced by the static mixer would results in the reduction of both the traveling distances and its dispersion of the disposed CO2 drops.
Space Utilization for Ocean Power Generation Technologies
Authors: Zambrano T. , Thurston S. , MacCready T.
Published: January 2009

This paper concerns how much ocean space would be utilized for a 10MW or 50MW ocean power plant. The most promising emerging technologies from space utilization points-of-view (i.e., power per unit sea area, environmental aspects, navigational aspects, cost, etc.) appear to be distributed subsea systems. A case example for a 10 MW subsea ocean power project would be 20 to 100 individual moored generators, positioned in an array. The units would generate electricity independently but be interconnected to a single transmission/communications infrastructure. Along with the size of the individual moored generators (which are relatively small), the calculation procedure for ocean space utilization takes into account that: (1) there is an optimum positioning for the individual moored units so that the energy extracted from one unit does not interfere with adjacent units; (2) there is a spacing criteria both among the individual units and surrounding the entire array for environmental, operations and maintenance, and navigational issues, and; (3) there is an optimum spacing to minimize electrical transmission and communication infrastructure costs. Several case examples are presented for distributed subsea systems. These examples range from 1 MW pilot scale to 10–100 MW utility scales. It has been calculated that a 10MW distributed subsea ocean power plant would occupy 100 acres of ocean space when taking into account ocean space utilization factors identified above. For larger utility scale facilities, ocean space utilization was calculated to be approximately 50 megawatts per square mile.
Evolutionary Design of Marine Riser Systems
Authors: Cunliffe Nicholas , Baxter Carl , McCarthy Timothy , Trim Andrew
Published: January 2009

It is said that nature attempts to solve the ‘problem of life’ through evolution. ‘Solutions’ are proposed which are then tested in the world around us. Natural selection ensures that the best characteristics are inherited by subsequent generations. This paper gives details of a new method of automated riser design and optimization using techniques based on evolutionary theory. Genetic algorithms are a subset of evolutionary computation which rely on natural selection to evolve good designs. A given design (e.g. riser system) is represented by a ‘genome’ in which the design variables are encoded in the form of ‘genes’. The optimization software interfaces with an industry standard marine simulation package for design evaluation which gives rise to a great deal of flexibility and few limitations on model complexity. The software can be used for whole system design including multiple risers or as an assistant for the optimization of specific design variables. The software is capable of evaluating systems using both static and dynamic simulations for any number of loadcase scenarios. The design of a titanium catenary gas export riser intended for Statoil’s Kristin semi-submersible platform in the North Sea is used to illustrate the method. The design created by the evolutionary software is a significant improvement on the design created using a traditional approach. The results demonstrate improvements in dynamic response together with a reduction in the riser bill of materials cost of approximately one-third, whilst the time spent on design was reduced by nearly an order of magnitude.
Fluid Structure Interactions at Towed Fishing Gears
Authors: Paschen Mathias , Niedzwiedz Gerd , Winkel Hans-Joachim
Published: January 2009

From the point of view of mechanics, trawls are considered as extremely flexible and partly extensible rope and net structures which are exposed to flow. Form and loads of such gears mainly depend on the corresponding velocity of inflow and also on the so-called rigging elements that are required for the horizontal and vertical spreading of the fishing gear. At the same time the fishing gear is acting on the surrounding fluid. These reactions can on the one hand lead to unsteady states in the fishing gear. On the other hand changes of pressure and velocity can be detected by the fish and can possibly influence the selectivity of the fishing gear. This lecture is focused on the presentation of special numerical and experimental methods both for calculating large net systems and for analysing the reactions of the structure to the fluid.
The Use of Implicit Safety Factors in the Reassessment of Existing Platforms in the Arabian Gulf
Authors: Zaghloul Hassan M. , Ronalds Beverley F.
Published: January 2009

Current engineering practice provides a safety level in the design of structures through the use of explicit safety factors (ESF), which consist of resistance factors (for working stress design or WSD) and/ or load factors (for load resistance factor design or LRFD). The WSD factors have been derived by experience, judgment and observation of actual behavior of existing structures, while LRFD factors were calibrated from WSD factors to yield, on average, similar safety/ reliability levels. In both methods, the proportioning of each element of a structure, rather than performance of the whole structure, is addressed. A platform is considered “unsafe” if ESF are consumed, which may be due to significant increase in the loading and/ or deterioration in the resistance. However, the presence of other safety factors, termed implicit safety factors (ISF), provides local and global safety levels that could considerably increase ESF, and may be utilized to avoid structural intervention, or at least limit its extent. The ISF are, in essence, available defenses for an existing structure, which contribute in a certain way to enhance the safety level. The recognition and exploitation of ISF may result in avoiding expensive construction intervention and bring about economical benefits without compromising the safety levels implied by design codes. The benefits extend to the decision-making process related to inspection, maintenance and operation of an existing structure. For a new design, the utilization of ISF may reduce structural weight and subsequently procurement, fabrication and installation costs. This paper reveals ISF and presents the basis of a development aiming at a method to account for their effect on the deterministic formulation of a code specific to the Arabian Gulf.
An Approach to Calculate the Probability of Wave Impact on an FPSO Bow
Authors: Guedes Soares C. , Pascoal R. , Anta˜o E. M. , Voogt A. J. , Buchner B.
Published: January 2009

This work aims at characterizing the probability of wave impact and expected impact load on the bow geometry of an FPSO. In order to determine the instants when impact occurs, an experimental program was performed on a specific bow shape. The bow was instrumented with pressure transducers and the test program, also making use of video recordings, was designed such that it was possible to determine the correlation between undisturbed wave shape and the impact pressure time traces. It has been found that wave impact at the bow is highly correlated with the local wave steepness, which for very high waves has at least second order effects. A comparison between the probability distributions of local wave steepness of the experimental undisturbed wave time trace and numerical simulations of second order wave theory is provided and it confirmed that the latter is very adequate for calculations. The experimental results were further used to determine how the probability of impact varies with free surface vertical velocity. It was found that the significant wave height of the sea state itself does not have significant influence on the result and a regression model is derived for that type of bow. The proposed model for determining the probability of impact load is based on combining both models. The analytical nature makes it fast and easy to expand to other cases of interest and some example calculations are shown to demonstrate the relative ease of the procedure proposed. The position of the impact is determined by the non-linear wave crests and the ship motions. The ship motions can be determined based on a linear response to the non-linear waves considered.
Design Rules for Marine Fish Farms in Norway: Calculation of the Structural Response of Such Flexible Structures to Verify Structural Integrity
Authors: Berstad Are Johan , Tronstad Harald , Ytterland Anders
Published: January 2009

As of April 1st 2004 all new marine fish farms in Norway need to be certified to comply with technical criteria in a new Norwegian Standard, NS 9415 (NAS, 2003). This paper gives an overview of the design rules. Marine fish farms have a strongly flexible hydroelastic behavior. The design rules have revealed the need for calculations to verify the structural capacity of such facilities. This paper describes how loads and response are derived on the fish farm structures. In order to account for the large geometrical deflections occurring in fish farm components such as the net and anchor cables which interacts with stiffer structural components, time domain simulations analysis of such facilities is required to assess the structural integrity. This paper report a proposed practical calculation method and results from model tests have been carried out to validate calculations. Good correspondence was shown. Additionally some applications are described.
A Novel Combined Power and Cooling Thermodynamic Cycle for Low Temperature Heat Sources: Part II — Experimental Investigation
Authors: Tamm Gunmar , Goswami D. Yogi
Published: January 2009

A combined thermal power and cooling cycle proposed by Goswami is under intensive investigation, both theoretically and experimentally. The proposed cycle combines the Rankine and absorption refrigeration cycles, producing refrigeration while power is the primary goal. A binary ammonia-water mixture is used as the working fluid. This cycle can be used as a bottoming cycle using waste heat from a conventional power cycle or an independent cycle using low temperature sources such as geothermal and solar energy. An experimental system was constructed to demonstrate the feasibility of the cycle and to compare the experimental results with the theoretical simulation. Results showed that the vapor generation and absorption condensation processes work experimentally, exhibiting expected trends, but with deviations from ideal and equilibrium modeling. The potential for combined turbine work and refrigeration output was evidenced in operating the system. Analysis of losses showed where improvements could be made, in preparation for further testing over a broader range of operating parameters.
Revising and Validating Spectral Irradiance Reference Standards for Photovoltaic Performance Evaluation
Authors: Myers Daryl R. , Emery Keith , Gueymard C.
Published: January 2009

In 1982, the American Society for Testing and Materials (ASTM) adopted consensus standard direct-normal and global-tilted solar terrestrial spectra (ASTM E891/E892). These standard spectra were intended to evaluate photovoltaic (PV) device performance and other solar-related applications. The International Standards Organization (ISO) and International Electrotechnical Commission (IEC) adopted these spectra as spectral standards ISO 9845-1 and IEC 60904-3. Additional information and more accurately representative spectra are needed by today’s PV community. Modern terrestrial spectral radiation models, knowledge of atmospheric physics, and measured radiometric quantities are applied to develop new reference spectra for consideration by ASTM.
Effect of Water and Serum Absorption on Wear of Unirradiated and Crosslinked UHMWPE Orthopaedic Bearing Materials
Authors: Laraia Kathryn , Leone Nicholas , MacDonald Rebecca , Blanchet Thierry
Published: January 2009

In addition to confounding mass-based wear measurements in serum-lubricated hip simulator experiments, fluid absorption by the acetabular cups may simultaneously modify the wear resistance of the ultra-high molecular weight polyethylene (UHMWPE) from which they are composed. To decouple the fluid absorption and wear processes enabling clearer investigation of this effect, absorption was first imposed during an initial stage where UHMWPE was exposed to pressurized (10MPa) fluid. This was followed by a second stage, where resultant wear behavior was assessed by a multidirectional pin-on-flat technique that, though still providing a serum-lubricating environment, does not promote the simultaneous fluid absorption occurring in hip simulator testing. Both unirradiated and highly-crosslinked UHMWPE were investigated, each with both bovine calf serum and water soaking exposures of duration to 129 days. The pressurized soaking of a highly-crosslinked UHMWPE decreased its wear resistance, causing an increase in wear rate by approximately 50% during subsequent serum-lubricated multidirectional pin-on-flat sliding tests as compared to non-soaked material. The magnitude of this effect did not appear to depend on whether the soaking fluid was water or serum, nor did it appear to depend on soak time provided it was at least of a 14-day duration during which more rapid transient fluid absorption occurs. Such soaking did not produce as pronounced an effect on unirradiated UHMWPE, at its lack of wear resistance likely causes the absorption-affected surface region to the completed removed within the earliest stages of sliding contact.
Analysis of Mixed Lubrication Effects in Simulated Gear Tooth Contacts
Authors: Holmes M. J. A. , Evans H. P. , Snidle R. W.
Published: January 2009

The paper presents results obtained using a transient analysis technique for point contact elastohydrodynamic lubrication (EHL) problems based on a formulation that couples the elastic and hydrodynamic equations. Results are presented for transverse ground surfaces in elliptical point contact that show severe film thinning and asperity contact at the transverse limits of the contact area. This thinning is caused by transverse leakage of the lubricant from the contact in the remaining deep valley features between the surfaces. A comparison is also made between the point contact results on the entrainment centre line and the equivalent line contact analysis. The extent of asperity contact is shown to be dependent on the Hertzian contact aspect ratio. It is also shown that transverse waviness (superimposed on the roughness) of even relatively small amplitude can lead to large increases in asperity contact rates over all waviness peaks in the contact.
Transient and Steady State Vibration Analysis of a Wavy Thrust Bearing
Authors: Zhao Hongmei , Choy F. K. , Braun M. J.
Published: January 2009

This paper describes a numerical procedure for analyzing the dynamics of transient and steady state vibrations in a wavy thrust bearing. The major effects of the wavy geometry and the operating parameters on the dynamic characteristics of the bearing had been discussed in previous work. The present study thus concentrates on examining the relationships between the development of the transient and steady state vibrations when operating conditions including rotational speed and load magnitude are parametrically varied. Special attention is given to the development of steady state vibrations from initial transients with comparisons and consequences to the overall system stability. Numerical based vibration signature analysis procedures are then used to identify and quantify the transient vibrations. The conclusions provide general indicators for designing wavy thrust bearings that are less susceptible to transients induced by external perturbations.
Height-Dependent Asperity Radii of Curvatures in a Contact and Friction Model
Authors: Adams George G. , Mu¨ftu¨ Sinan
Published: January 2009

The effect of a height-dependent asperity radius of curvature is accounted for in a recently developed scale-dependent model of contact and friction. The contact and friction model includes the effects of adhesion, using the Maugis model, and of scale-dependent friction, using the Hurtado and Kim single asperity friction model. This multi-asperity model has been modified to include the effect of non-contacting asperities. The results indicate the types of conditions under which the effects of a height-dependent asperity radius of curvature affects friction.
Activities of Dalbavancin against a Worldwide Collection of 81,673 Gram-Positive Bacterial Isolates
Authors: Biedenbach Douglas J. , Bell Jan M. , Sader Helio S. , Turnidge John D. , Jones Ronald N.
Published: January 2009

Dalbavancin, a long-acting lipoglycopeptide, was evaluated against 81,673 isolates of staphylococci, enterococci, and streptococci collected from 33 countries during worldwide resistance surveillance (2002 to 2007). Regardless of susceptibility to oxacillin, comparable potencies for dalbavancin againstStaphylococcus aureusand coagulase-negative staphylococci from all countries were noted (MIC90, 0.06 to 0.12 μg/ml). Vancomycin-susceptibleEnterococcusspp. had dalbavancin MIC90s comparable to those for staphylococci, whereas vancomycin-resistant strains were more resistant (MIC50, >4 μg/ml). β-Hemolytic and viridians group streptococci were very susceptible to dalbavancin (MIC90, ≤0.03 μg/ml). Overall, dalbavancin was ≥16-fold more active than vancomycin against the monitored gram-positive species.
A Pseudouridine Synthase Homologue Is Critical to Cellular Differentiation inToxoplasma gondii
Authors: Anderson Matthew Z. , Brewer Jeremy , Singh Upinder , Boothroyd John C.
Published: January 2009

Toxoplasma gondiiis a haploid protozoan parasite infecting about one in seven people in the United States. Key to the worldwide prevalence ofT. gondiiis its ability to establish a lifelong, chronic infection by evading the immune system, and central to this is the developmental switch between the two asexual forms, tachyzoites and bradyzoites. A library of mutants defective in tachyzoite-to-bradyzoite differentiation (Tbd−) was created through insertional mutagenesis. This library contains mutants that, compared to the wild type, are between 20% and 74% as efficient at stage conversion. Two mutants, TBD5 and TBD8, with disruptions in a gene encoding a putative pseudouridine synthase, PUS1, were identified. The disruption in TBD8 is in the 5′ end of thePUS1gene and appears to produce a null allele with a 50% defect in differentiation. This is about the same switch efficiency as obtained with an engineeredpus1deletion mutant (Δpus1). The insertion in TBD5 is within thePUS1coding region, and this appears to result in a more extreme phenotype of only ∼10% switch efficiency. Complementation of TBD8 with the genomicPUS1allele restored wild-type differentiation efficiency. Infection of mice withpus1mutant strains results in increased mortality during the acute phase and higher cyst burdens during the chronic infection, demonstrating an aberrant differentiation phenotype in vivo due toPUS1disruption. Our results suggest a surprising and important role for RNA modification in this biological process.
The
Schistosoma mansoni
Protein Sm16/SmSLP/SmSPO-1 Assembles into a Nine-Subunit Oligomer with Potential To Inhibit Toll-Like Receptor Signaling
Authors: Brännström Kristoffer , Sellin Mikael E. , Holmfeldt Per , Brattsand Maria , Gullberg Martin
Published: January 2009

The Sm16/SmSLP/SmSPO-1 (Sm16) protein is secreted by the parasite
Schistosoma mansoni
during skin penetration and has been ascribed immunosuppressive activities. Here we describe the strategy behind the design of a modified Sm16 protein with a decreased aggregation propensity, thus facilitating the expression and purification of an Sm16 protein that is soluble in physiological buffers. The Stokes radii and sedimentation coefficients of recombinant and native proteins indicate that Sm16 is an approximately nine-subunit oligomer. Analysis of truncated Sm16 derivatives showed that both oligomerization and binding to the plasma membrane of human cells depend on multiple C-terminal regions. For analysis of immunomodulatory activities, Sm16 was expressed in
Pichia pastoris
to facilitate the preparation of a pyrogen/endotoxin-free purified protein. Recombinant Sm16 was found to have no effect on T-lymphocyte activation, cell proliferation, or the basal level of cytokine production by whole human blood or monocytic cells. However, Sm16 exerts potent inhibition of the cytokine response to the Toll-like receptor (TLR) ligands lipopolysaccharide (LPS) and poly(I:C) while being less efficient at inhibiting the response to the TLR ligand peptidoglycan or a synthetic lipopeptide. Since Sm16 specifically inhibits the degradation of the IRAK1 signaling protein in LPS-stimulated monocytes, our findings indicate that inhibition is exerted proximal to the TLR complex.
Contact-Dependent Growth Inhibition Causes Reversible Metabolic Downregulation in
Escherichia coli
Authors: Aoki S. K. , Webb J. S. , Braaten B. A. , Low D. A.
Published: January 2009

Contact-dependent growth inhibition (CDI) is a mechanism identified in
Escherichia coli
by which bacteria expressing two-partner secretion proteins encoded by
cdiA
and
cdiB
bind to BamA in the outer membranes of target cells and inhibit their growth. A third gene in the cluster,
cdiI
, encodes a small protein that is necessary and sufficient to confer immunity to CDI, thereby preventing cells expressing the
cdiBA
genes from inhibiting their own growth. In this study, the
cdiI
gene was placed under
araBAD
promoter control to modulate levels of the immunity protein and thereby induce CDI by removal of arabinose. This CDI autoinhibition system was used for metabolic analyses of a single population of
E. coli
cells undergoing CDI. Contact-inhibited cells showed altered cell morphology, including the presence of filaments. Notably, CDI was reversible, as evidenced by resumption of cell growth and normal cellular morphology following induction of the CdiI immunity protein. Recovery of cells from CDI also required an energy source. Cells undergoing CDI showed a significant, reversible downregulation of metabolic parameters, including aerobic respiration, proton motive force (Δp), and steady-state ATP levels. It is unclear whether the decrease in respiration and/or Δp is directly involved in growth inhibition, but a role for ATP in the CDI mechanism was ruled out using an
atp
mutant. Consistent with the observed decrease in Δp, the phage shock response was induced in cells undergoing CDI but not in recovering cells, based on analysis of levels of
pspA
mRNA.
Particle retention during respiration and particulate feeding in the suspension-feeding blackfish,Orthodon microlepidotus
Authors: Sanderson S. Laurie , Cech Jr. Joseph J.
Published: January 2009

Juvenile blackfish (Orthodon microlepidotus) retained styrene microspheres (30–90 μm) during respiration in the absence of food. The fish retained significantly more microspheres when particulate feeding on Artemia adults, suspension feeding on Artemia nauplii, or in the presence of Artemia extract than when respiring in the absence of food. The frequency distribution of microsphere sizes retained during respiration did not differ significantly from that retained during feeding, a result that is consistent with the hypothesis that the site and method of particle retention during respiration and particulate feeding do not differ from those operating during suspension feeding. There was significant interindividual variability in the number of particles retained. Some individuals retained consistently fewer microspheres than other individuals of similar size and age, suggesting that further study is needed to quantify interindividual variation in other factors (e.g., stroke volume, ventilation rate, or mucus secretion) that have the potential to affect particle retention rates. Our results have implications for the energetics of suspension-feeding fishes, the impacts of suspension-feeding fishes on plankton communities, and the exposure of these fishes to toxic phytoplankton strains and particle-bound organic chemicals.
Experimental rearing and growth of planktonic Octopus vulgaris from hatching to settlement
Authors: Villanueva Roger
Published: January 2009

The common octopus, Octopus vulgaris, weighing 1.4 mg at hatching and reared in the laboratory (mean 21.2 °C), doubled their weight roughly every 8.5 days to a mean of 173.2 mg after 60 days when they became benthic. Changes in paralarval allometry during development were strongly marked in the case of arm length: suckers were added and the arms grew concomitantly from day 10 and growth rate accelerated from day 20. Neither cannibalism nor schooling behaviour occurred during the planktonic stage. Survival rate to settlement was 8.9%. The paralarvae of O. vulgaris exhibited presettlement reflexes from day 36 and settled between days 47 and 54, suggesting considerable potential for dispersal. Comparison of these results with previous studies suggests that paralarvae settle when they reach a critical size irrespective of age, and that the duration of the planktonic period is probably temperature dependent. After settlement, octopuses still bore Koelliker organs, lacked papillae on the body surface, were capable of feeding on inert prey, and exhibited negative phototaxis and reclusive behaviour like adults. The main period of settlement under natural conditions in the northwestern Mediterranean Sea is probably September–October.
Aliphatic hydrocarbons in sediments: a chronic toxicity study with winter flounder (Pleuronectes americanus) exposed to oil well drill cuttings
Authors: Payne J. F. , Fancey L. L , Hellou J. , King M. J. , Fletcher G. L.
Published: January 2009

Most studies on the chronic toxicity of hydrocarbons have focused on the polycyclic aromatic component; however, information is also required on the chronic toxicity of other classes of hydrocarbons. This need has been brought to the forefront by the controversy about the use of aliphatic hydrocarbon-based drilling fluids at petroleum development sites in the marine environment. Dose–response relationships were studied for a variety of indices in a chronic toxicity study with winter flounder (Pleuronectes americanus) exposed to sediments contaminated with drill cuttings enriched in hydrocarbons. The indices investigated were biologically meaningful and included organ and body condition indices, muscle and liver energy reserves, mixed-function oxygenase detoxification enzymes, blood parameters, and liver and gill histopathology. There was no evidence of dose–response relationships and most indices remained unaffected even at the highest exposure level. The study supports the hypothesis that the aliphatic component of complex hydrocarbon mixtures is relatively nontoxic, and it will be of particular interest for evaluating the scope of environmental risks associated with the use of oil-base drilling fluids in the marine environment.
ON THE DISTRIBUTION OF COUNTER-DEPENDENT NONLINEAR CONGRUENTIAL PSEUDORANDOM NUMBER GENERATORS IN RESIDUE RINGS
Authors: EL-MAHASSNI EDWIN D. , GOMEZ DOMINGO
Published: January 2009

Nonlinear congruential pseudorandom number generators can have unexpectedly short periods. Shamir and Tsaban introduced the class of counter-dependent generators which admit much longer periods. In this paper, using a technique developed by Niederreiter and Shparlinski, we present discrepancy bounds for sequences of s-tuples of successive pseudorandom numbers generated by counter-dependent generators modulo a composite M.
Mycobacterial Subversion of Chemotherapeutic Reagents and Host Defense Tactics: Challenges in Tuberculosis Drug Development
Authors: Nguyen Liem , Pieters Jean
Published: January 2009

Recent worldwide emergence of multidrug-resistant and extensively drug-resistant tuberculosis is threatening to destabilize tuberculosis control programs and urging global attention to the development of alternative tuberculosis therapies. Major roadblocks limiting the development and effectiveness of new drugs to combat tuberculosis are the profound innate resistance of Mycobacterium tuberculosis to host defense mechanisms as well as its intrinsic tolerance to chemotherapeutic reagents. The triangle of interactions among the pathogen, the host responses, and the drugs used to cure the disease are critical for the outcome of tuberculosis. We must better understand this three-way interaction in order to develop drugs that are able to kill the bacillus in the most effective way and minimize the emergence of drug resistance. Here we review our recent understanding of the molecular basis underlying intrinsic antibiotic resistance and survival tactics of M. tuberculosis. This knowledge may help to reveal current targets for the development of novel antituberculosis drugs.
Mammalian Nicotinic Acetylcholine Receptors: From Structure to Function
Authors: Albuquerque Edson X. , Pereira Edna F. R. , Alkondon Manickavasagom , Rogers Scott W.
Published: January 2009

The classical studies of nicotine by Langley at the turn of the 20th century introduced the concept of a “receptive substance,” from which the idea of a “receptor” came to light. Subsequent studies aided by the Torpedo electric organ, a rich source of muscle-type nicotinic receptors (nAChRs), and the discovery of α-bungarotoxin, a snake toxin that binds pseudo-irreversibly to the muscle nAChR, resulted in the muscle nAChR being the best characterized ligand-gated ion channel hitherto. With the advancement of functional and genetic studies in the late 1980s, the existence of nAChRs in the mammalian brain was confirmed and the realization that the numerous nAChR subtypes contribute to the psychoactive properties of nicotine and other drugs of abuse and to the neuropathology of various diseases, including Alzheimer's, Parkinson's, and schizophrenia, has since emerged. This review provides a comprehensive overview of these findings and the more recent revelations of the impact that the rich diversity in function and expression of this receptor family has on neuronal and nonneuronal cells throughout the body. Despite these numerous developments, our understanding of the contributions of specific neuronal nAChR subtypes to the many facets of physiology throughout the body remains in its infancy.
Production of Nitric Oxide and Expression of Inducible Nitric Oxide Synthase in Ovarian Cystic Tumors
Authors: Nomelini Rosekeila Simões , Ribeiro Lívia Carolina de Abreu , Tavares-Murta Beatriz Martins , Adad Sheila Jorge , Murta Eddie Fernando Candido
Published: January 2009

Tumor sections from nonneoplastic (n= 15), benign (n= 28), and malignant ovarian tumors (n= 20) were obtained from 63 women. Immunohistochemistry of the tumor sections demonstrated that inducible nitric oxide synthase (iNOS) expression was increased in ovarian cancer samples compared to nonneoplastic or benign tumor samples. Using the Griess method, nitric oxide (NO) metabolite levels were also found to be elevated in malignant tumor samples compared to benign tumor samples (P< .05). For stage I ovarian cancer, intracystic NO levels >80 μM were more frequent than NO levels <80 μM, and iNOS expression in well‐differentiated carcinomas was greater than in moderately/poorly differentiated carcinomas (P< .05). These data suggest an important role for NO in ovarian carcinogenesis.
Image Segmentation Using Gray‐Scale Morphology and Marker‐ControlledWatershed Transformation
Authors: Parvati K. , Prakasa Rao B. S. , Mariya Das M.
Published: January 2009

Segmentation, a new method, for color, gray‐scale MR medical images, and aerial images, is proposed. The method is based on gray‐scale morphology. Edge detection algorithm includes function edge and marker‐controlled watershed segmentation. It features the simple algorithm implemented in MATLAB. The watershed segmentation has been proved to be a powerful and fast technique for both contour detection and region‐based segmentation. In principle, watershed segmentation depends on ridges to perform a proper segmentation, a property that is often fulfilled in contour detection where the boundaries of the objects are expressed as ridges. For region‐based segmentation, it is possible to convert the edges of the objects into ridges by calculating an edge map of the image. Watershed is normally implemented by region growing, based on a set of markers to avoid oversegmentation.
What Kind of Canon Do the Lectionaries Constitute?
Authors: Sloyan Gerard S.
Published: January 2009

The Roman Catholic Church inaugurated a three-year cycle of three readings from the Bible entitled LECTIONARY FOR MASS in Advent, 1969. Four U.S. Protestant Churches shortly produced their own patterned on it, one of them proposed for use by eight of the member Churches of the Consultation on Church Union (the ninth had its own). At present there are three in use, the Catholic lectionary that is internationally employed, one composed by the U.S. Episcopal Church for its revised BOOK OF COMMON PRAYER, and the REVISED COMMON LECTIONARY of the Consultation on Common Texts. The last named has been adopted by the Lutheran, Reformed tradition, and Methodist Churches that had previously developed a lectionary of their own. The proclamation of God's life-giving and redemptive deed in Jesus Christ in the power of the Holy Spirit is the architectonic principle governing all the lections proposed. In aid of this, the ancient resort to typology has been employed, which sees a prefiguring of something in every Gospel pericope in some incident or passage in the First Testament. Fearful that the fullness of God's revelation to Israel may have been obscured by this technique, the RCL has proposed lengthier readings from that Testament unrelated to the day's Gospel for one half of each year. This article will attempt to answer the question posed in the title.