bluuebunny/crossref_metadata_2025 huggingface dataset:
State of the Art Thermal Spray Technology in the International Waste to Energy Industry
Authors: Hall Iain , Han Kwang , Shui Zheng-Rong
Published: December 2008

International Waste to Energy and Incineration markets are likely to continue to grow in capacity over the next 5 to 6 years. With this comes a greater need to burn more corrosive materials combust at higher temperatures and extract more energy. The reliability burden that this places on operators of plants will re-open opportunities for thermal spray solutions. Where maintenance costs, opportunity costs and access restrictions may preclude alternative in-situ technologies, thermal spray technology may fill a gap in providing new reliable and flexible process and materials technologies for at least the midterm protection of water wall and superheater tubes. The state of the art of the technology is such that coating performance in WTE corrosive environments now approach the performance of corrosion resistant wrought materials. This is verified through accurate laboratory modeling and scale tests and trials conducted by OEM’s and plants.
A New Air Compressor Cooling System for the Pinellas County Resource Recovery Facility
Authors: White Thomas M.
Published: December 2008

Due to serious deterioration of aluminum fins on two dry coolers only 6 years after initial installation, the potential to disrupt operation of the 3,000 tons per day (tpd) Pinellas County Resource Recovery Facility was a real concern. A new system upgrade was required to provide reliable cooling of the glycol liquid system. This system dissipates the heat rejection requirements of the process and instrument air compressors, particularly critical during Florida’s hot summer months. A second issue was the need to provide redundancy, which was not designed into the original installation. The selected system included two plate and frame coolers along with two pumps located next to the existing cooling tower (C.T.) basin. Water from the C.T. basin is pumped through one plate and frame cooler, reducing the temperature of the glycol liquid. The water then flows back to the C.T. basin. The construction work, completed in August 2003, provides in excess of 200% redundancy and has been in successful operation since that date.
An Innovative Boiler Cleaning Method Using a Rotary Cable Swivel Tool
Authors: Marra Dominic
Published: December 2008

The boiler generating bank (convective) sections of waste to energy boilers are commonly found to be very limited in regards to personnel access. The Miami-Dade County Resources Recovery Facility has had a challenge in the past to effectively clean this section of the boiler either on line or within a timely manner during outages. In 2003 the company used a new innovative method for cleaning this section off line. The boilers were 100% clean in 1/2 to 1/3 the usual time. The new method involved high-pressure industrial water blasting as typically used, with the exception of the water delivery device/system. Normally the water delivery method involves personnel placed in the boiler with hand held high-pressure water lances. They require confined space monitoring, lighting, scaffolding, proper air supply, frequent breaks, rain suits, full face shields and other PPE for safety inside the boiler. These factors combined with the limited space severely constrain the personnel and their effectiveness when using the water lances. Cleaning is compromised and has led to poor effectiveness and long duration cleanings. Explosives have also been tried to help augment cleaning. The new method used in 2003 involved no personnel in the boiler. Instead, for the water delivery system, a support cable is erected across the boiler upon which a rotary cable swivel tool (CST) is mounted. The tool has connections for high-pressure water and plant air and a simple winch for traversing the tool across the furnace. Very effective cleaning was accomplished from drum to drum, a distance of 20 feet (6.1 m). Depending on the application, the water pressure can be adjusted for maximum effectiveness. The air pressure is also adjusted to control the speed at which the rotary nozzles spin to best match the fouled conditions. The orientation and number of nozzles is also optimized for each application. This paper details the results of using the rotary Cable Swivel Tool (CST) in the generating bank section of the boilers and discusses related operational and maintenance benefits.
Improvement in Operating and Maintenance Cost With a Fabric Filter Conversion Using Polytetrafluoroethylene (PTFE) Membrane Filter Media
Authors: Darrow John , Grego Paul , Austin Brenda
Published: December 2008

Wheelabrator Technologies is owner and operator of the 2250 ton per day North Broward County, Florida, facility. The plant consists of three lines rated at 750 tons/day. Each line is equipped with a spray dryer absorber/fabric filter. The original fabric filter design was a shake-deflate baghouse with ten compartments of 180 bags each. The typical bag life was one year with the shake-deflate baghouse using standard woven fiberglass bags. Frequent bag failures led to high operating and maintenance cost for the system. The initial upgrade was a conversion from a shake-deflate baghouse to a reverse-air baghouse with sonic horns. The resultant bag life was improved to two years, which represented a significant reduction in maintenance cost. The latest upgrade for the baghouse system was the installation of PTFE membrane/fiberglass filter bags. The change in the filter media resulted in a dramatic improvement in performance. The baghouse cleaning frequency dropped from 360 cycles per day to approximately 50 cycles per day. The average differential pressure across the baghouse system also dropped by 6 in. w. g. The membrane filter bags have achieved over two years life to date and have significantly reduced operating and maintenance costs associated with the baghouse. This paper will detail the steps taken in the conversion from the original shake-deflate design using standard filter bags to the reverse-air with sonic horns using membrane bags. An analysis of the cost of the upgrades and subsequent savings for each step will be included.
Lime Usage Reduction at the Delaware Valley Resource Recovery Facility
Authors: Nicholson Stewart , Clark John
Published: December 2008

Waste to Energy facilities in the U.S. collectively spend over $20 million per year on lime for flue gas treatment. Individually, most plants spend between $300,000 and $1 million per year on lime. This expense is often the plant’s largest for a consumable material and is expected to increase as emission limits become more stringent.
Technical Challenges and Abatements of a Mass Burn Waste-to-Energy Plant Co-Incinerating Municipal Solid Waste and Industrial Waste
Authors: Shu Abraham
Published: December 2008

The application of mass burn waste-to-energy (WTE) plants is becoming more popular in Asia, not just for proper disposal of municipal solid waste (MSW) like most plants in the western world do but stretched by many Asian plants to co-incinerate non-hazardous industrial waste (IW) in order to maximize the use of the plant facilities, hence to save costs from building facilities specifically for treating IW. As the plants are designed with conventional considerations practiced in the western world and the original designs are not oriented towards co-incinerating large percentages of IW, plant operators frequently face challenges such as unstable combustion quality, frequent boiler tube rupture amplified by co-incineration, inadequacy of the conventional control systems and other facilities to handle the co-incineration application. One co-incineration WTE plant in Taiwan is used as an example to illustrate the significance of these challenges, some measures taken to abate the problems and the cost impacts. Suggestions are also provided for technical management of co-incineration plants.
Seghers Boiler Prism: A Proven Primary Measure Against High Temperature Boiler Corrosion
Authors: Adams Bart , Diederen Herman S. W. , Peeters Kris , Wijnhoven Jac P. F. , Eeraerts Dirk
Published: December 2008

This paper constitutes a follow-up on a presentation at NAWTEC 10 (2001) [1]. It contains novel insights regarding the operation of the Seghers Boiler Prism and its effectiveness as a primary measure against high temperature boiler corrosion in WtE plants. Starting from the currently available fundamental understanding on high temperature corrosion and the main features of the Boiler Prism, the operation as a primary measure is explained. Since the previous presentation, three additional Boiler Prisms were successfully commissioned as a retrofit at a large WtE facility (3 × 705tons/day at 4,700BTU/lb; 110tons/hour steam at 1,450psi, 750°F) in the Netherlands. Together with the previously installed prisms, this brings the combined operational experience from all trains to more than 15 years. The main data and experience of the retrofit project in the Netherlands are discussed and results regarding the performance of the prism are presented in detail. The latter are based both on existing process monitors as well as dedicated measurement campaigns and include: • temperature and oxygen distribution in the 1st radiation pass, • feedback on corrosion rates, • influence on the combustion quality, and • impact on the effectiveness of the mechanical cleaning equipment. The results confirm the effectiveness of the prism as a primary measure against high temperature boiler corrosion and highlight the additional operational benefits.
The Fourth Dimension for Waste Management in the United States: Thermoselect Gasification Technology and the Hydrogen Energy Economy
Authors: Schilli Joseph
Published: December 2008

Waste management in the United States presently has the following major three dimensions: Sanitary landfills, recycling, waste to energy predominantly based on the technologies of mass bum technology or refuse derived fuel. These three dimensions have undergone significant evolution during the past three decades. The design of sanitary landfills has evolved to include environmental protection features such as bottom liners, leachate collection systems and landfill gas management systems. Material recycling programs, many based on materials recycling facilities, have become more prevalent. Approximately 100 operating waste to energy facilities (“Facilities”) now exist in the United States. Improvements in the air pollution control systems incorporated in the Facilities have significantly lowered their air emissions. A fourth dimension, waste gasification technology, is evolving as a viable component of a waste management system and the hydrogen energy economy.
Use of Multicomponent Infrared Gas Analyzers at Waste-to-Energy Facilities
Authors: Baker Ronald , Peters Robert , Chikhliwala Edul
Published: December 2008

Multicomponent Infrared Gas analyzers have been a workhorse as Continuous Emissions Monitoring Systems (CEMS) in the waste-to-energy (WTE) application for the past two decades. It is the technique of choice for many facilities. With obsolescence for electronics, instrumentation and data acquisition systems (DAS) averaging less than 10 years, the earlier multicomponent CEMS are being upgraded to what is now a third generation of that technology. This paper describes the evolution of the three generations of multicomponent CEMS. The evaluation of this technology in the WTE application encompasses the operating histories of nearly two dozen facilities demonstrating compliance with this type of CEMS. Specific details explaining the sampling systems, analyzer optics & controls, interface and communication with plant distributed control systems, and DAS systems are presented. Relative accuracy test audit (RATA) results, CEMS availability histories and annual maintenance costs are reviewed presenting a unique insight into both initial capital costs and operating costs. Actual annual man-hour totals for preventive maintenance (PM), unscheduled maintenance, and annual consumable parts costs are provided. Advances in computer capabilities have provided an opportunity for CEMS functions to not only become more comprehensive but also more robust. Key among these advances is the ability for factory-support services to be provided not only for the software platform but now even down to the basic auditing parameters of the analyzers themselves. Third generation CEMS now feature remote access of the analyzers from the instrumentation repair shop, the vendor’s factory or from the company’s technical service center.
Can an Electron Rotate a Brick?
Authors: Bohren Craig F.
Published: December 2008

In The Theory of Almost Everything,1 Robert Oerter asserts the following: “Take a beam of electrons that are all spinning in the same direction and fire it at, say, a brick. If you could keep this up for long enough, and if there were no other forces acting on the brick, the electrons would transfer their rotation to the brick, and it would begin to rotate.” Although this may awe credulous readers, skeptical physics students and their teachers ought to ask: Is it true that an electron can rotate a brick? To answer this requires bringing together elementary concepts from several areas of physics and doing the kind of back-of-the-envelope calculations students should be taught to do early on in their scientific education.
Plucked String on a Shoestring Budget
Authors: Gluck Paul
Published: December 2008

The physics of the plucked string has been treated in many articles and books.1–4 For our 12th-grade high school physics laboratory, we have built a cheap, simple sonometer apparatus for each pair of students on which they may investigate some interesting phenomena that arise when a string is plucked. Among these are the generation of harmonics (overtones) and the way their number depends on the length of a string and on where one plucks, the relation between the frequencies of the fundamental and those of the harmonics, and the way these are affected by changes in the length and the tension in the string. Such an experiment will help students appreciate the working of stringed musical instruments and, in particular, the contribution of overtones to the richness of sound produced.
Measuring Terrestrial Ozone from Historic Astronomical Spectra
Authors: Griffin Elizabeth
Published: December 2008

“Ozone” is a sensitive topic that arouses interest everywhere. Its presence in the stratosphere affects us all, and its threatened reduction would have such dire consequences that it energizes international campaigns, influences the thinking of governments, and activates substantial alterations in the accustomed habits of millions throughout the world. However, the properties of ozone are not that well known by most people (what is “known” about ozone has generally been relayed through various media channels), while the actual facts concerning its concentration and in particular its reduction require sophisticated scientific measurements that are only accessible to a few and are limited by data that have not always been as plentiful as they are nowadays. This paper describes a new initiative to examine overlooked but potentially informative ozone data from last century's astronomical records.
Administratium: A 20th-Anniversary Update
Authors: DeBuvitz William
Published: December 2008

Perhaps the readers of The Physics Teacher have come across a humorous little story on the Internet about the discovery of an element called “Administratium”1 (or one of its variants “Governmentium,” “Bureaucratium,” etc.), which behaved like college administrations. Some of these readers might recall seeing it in print many years ago. In fact, it first appeared 20 years ago in the January 1989 issue of The Physics Teacher under the heading “Farcical Physics” and I was the author. I came up with the idea in February of 1988 while giving a physics exam at Middlesex County College in Edison, NJ. I was reading a memo from the college administration about the latest reorganization, with its usual increase in vice presidents, assistants to the vice presidents, etc., looked over at a large periodic chart on the wall, and it all came together. I originally posted the “Administratium” story on a bulletin board at the college and the faculty found it funny. I then decided to send it to The Physics Teacher. I was concerned about offending Middlesex College, so I asked that my name be omitted from the article. It turned out that this was unnecessary—the college administration was a good sport about it. What was surprising to me was how this little story spread. What was even more surprising was how many people took credit for it. I guess I invited this by not using my name in the original publication. If you Google “Administratium,” you will get over 10,000 hits in different languages, with many people taking credit. I heard it read on The Osgood File and the discovery of “Administratium” was awarded an Ignoble Prize. A humorous story like this seems more appropriate for the Journal of Irreproducible Results. In fact, it was published in the January–February 1990 issue. Needless to say, I was getting a bit irritated by seeing so many people taking credit for my story. I contacted Norman Sperling, the editor of the JIR, about this and he suggested I write about the whole experience. I wrote an article that was published in the May 2005 issue and I extended the “Administratium” story to include newly discovered chemical properties. At the 20th anniversary of its publication, I feel it is important to clear up any question about the authorship in the magazine that first published the story.
Quarked! — Adventures in Particle Physics Education
Authors: MacDonald Teresa , Bean Alice
Published: December 2008

Particle physics is a subject that can send shivers down the spines of students and educators alike—with visions of long mathematical equations and inscrutable ideas. This perception, along with a full curriculum, often leaves this topic the road less traveled until the latter years of school. Particle physics, including quarks, is typically not introduced until high school or university.1,2 Many of these concepts can be made accessible to younger students when presented in a fun and engaging way. Informal science institutions are in an ideal position to communicate new and challenging science topics in engaging and innovative ways and offer a variety of educational enrichment experiences for students that support and enhance science learning.3 Quarked!™ Adventures in the Subatomic Universe, a National Science Foundation EPSCoR-funded particle physics education program, provides classroom programs and online educational resources.
Relativistic Velocity Addition Law from Machine Gun Analogy
Authors: Rothenstein Bernhard , Popescu Stefan
Published: December 2008

Many derivations of the relativistic addition law of parallel velocities without use of the Lorentz transformations (LT) are known.1–5 Some of them are based on thought experiments that require knowledge of the time dilation and the length contraction effects.1,4,5 Other derivations involve the Doppler effect in the optic domain considered from three inertial reference frames in relative motion.6 A few derivations simply involve only the principle of constancy of the light velocity.2 Such derivations are interesting for the teaching of special relativity theory since the relativistic addition of velocities leads directly to the LT.7 The derivation we propose is based on a machine gun-target analogy8 of the acoustic Doppler effect, considered from the rest frame of the machine gun and from the rest frame of the target.
Apparatus Review: Cenco Wave Apparatus
Authors: Greenslade Thomas B.
Published: December 2008

Some apparatus from the 19th century illustrates the phenomena of physics so well that it crops up again in the 21st century. An example is the combined transverse and longitudinal wave machine in Fig. 1. This is in the current Cenco/Sargent-Welch catalog under the name of “Wave Apparatus” (Cat. No. WLS-1755-90) and sells for $49.95.
Electron Cryomicroscopy of
E. coli
Reveals Filament Bundles Involved in Plasmid DNA Segregation
Authors: Salje Jeanne , Zuber Benoît , Löwe Jan
Published: December 2008

Bipolar elongation of filaments of the bacterial actin homolog ParM drives movement of newly replicated plasmid DNA to opposite poles of a bacterial cell. We used a combination of vitreous sectioning and electron cryotomography to study this DNA partitioning system directly in native, frozen cells. The diffraction patterns from overexpressed ParM bundles in electron cryotomographic reconstructions were used to unambiguously identify ParM filaments in
Escherichia coli
cells. Using a low–copy number plasmid encoding components required for partitioning, we observed small bundles of three to five intracellular ParM filaments that were situated close to the edge of the nucleoid. We propose that this may indicate the capture of plasmid DNA within the periphery of this loosely defined, chromosome-containing region.
Glucosinolate Metabolites Required for an
Arabidopsis
Innate Immune Response
Authors: Clay Nicole K. , Adio Adewale M. , Denoux Carine , Jander Georg , Ausubel Frederick M.
Published: December 2008

The perception of pathogen or microbe-associated molecular pattern molecules by plants triggers a basal defense response analogous to animal innate immunity and is defined partly by the deposition of the glucan polymer callose at the cell wall at the site of pathogen contact. Transcriptional and metabolic profiling in
Arabidopsis
mutants, coupled with the monitoring of pathogen-triggered callose deposition, have identified major roles in pathogen response for the plant hormone ethylene and the secondary metabolite 4-methoxy-indol-3-ylmethylglucosinolate. Two genes,
PEN2
and
PEN3
, are also necessary for resistance to pathogens and are required for both callose deposition and glucosinolate activation, suggesting that the pathogen-triggered callose response is required for resistance to microbial pathogens. Our study shows that well-studied plant metabolites, previously identified as important in avoiding damage by herbivores, are also required as a component of the plant defense response against microbial pathogens.
Rapid Membrane Disruption by a Perforin-Like Protein Facilitates Parasite Exit from Host Cells
Authors: Kafsack Björn F. C. , Pena Janethe D. O. , Coppens Isabelle , Ravindran Sandeep , Boothroyd John C. , Carruthers Vern B.
Published: December 2008

Perforin-like proteins are expressed by many bacterial and protozoan pathogens, yet little is known about their function or mode of action. Here, we describe
Toxoplasma
perforin-like protein 1 (TgPLP1), a secreted perforin-like protein of the intracellular protozoan pathogen
Toxoplasma gondii
that displays structural features necessary for pore formation. After intracellular growth, TgPLP1-deficient parasites failed to exit normally, resulting in entrapment within host cells. We show that this defect is due to an inability to rapidly permeabilize the parasitophorous vacuole membrane and host plasma membrane during exit. TgPLP1 ablation had little effect on growth in culture but resulted in a reduction greater than five orders of magnitude of acute virulence in mice. Perforin-like proteins from other intracellular pathogens may play a similar role in microbial egress and virulence.
Foraminiferal Isotope Evidence of Reduced Nitrogen Fixation in the Ice Age Atlantic Ocean
Authors: Ren H. , Sigman D. M. , Meckler A. N. , Plessen B. , Robinson R. S. , Rosenthal Y. , Haug G. H.
Published: December 2008

Fixed nitrogen (N) is a limiting nutrient for algae in the low-latitude ocean, and its oceanic inventory may have been higher during ice ages, thus helping to lower atmospheric CO
2
during those intervals. In organic matter within planktonic foraminifera shells in Caribbean Sea sediments, we found that the
15
N/
14
N ratio from the last ice age is higher than that from the current interglacial, indicating a higher nitrate
15
N/
14
N ratio in the Caribbean thermocline. This change and other species-specific differences are best explained by less N fixation in the Atlantic during the last ice age. The fixation decrease was most likely a response to a known ice age reduction in ocean N loss, and it would have worked to balance the ocean N budget and to curb ice age–interglacial change in the N inventory.
Modelling the non-linear multiple-lag effects of ambient temperature on mortality in Santiago and Palermo: a constrained segmented distributed lag approach
Authors: Muggeo V M , Hajat S
Published: December 2008

Objectives:

Exposure to ambient temperature can affect mortality levels for days or weeks following exposure, making modelling such effects in regression analysis of daily time-series data complex.

Methods:

We propose a new approach involving a multi-lag segmented approximation to account for the non-linear effect of temperature and the use of two different penalised spline bases to model the distributed lag of both heat and cold exposure. Compared with standard splines, the novel penalised framework is more flexible at short lags where change in coefficients is greatest, and selection of the maximum lag appears substantially less important in determining the overall pattern of the effect.

Results:

Applying the approach to daily mortality in Santiago (Chile) and Palermo (Italy), we observed a heat effect that was mostly immediate and followed by negative estimates consistent with short-term mortality displacement (harvesting). Cold effects were mostly positively sustained and more evenly distributed across the 60-day analysis period: in Santiago we estimated an overall increase in deaths of 2.36% (95% CI 0.26% to 4.51%) in the 65+ age group associated with every 1°C decrease below the cold threshold, and an increase of 1.11% (0.09% to 2.14%) per 1°C for Palermo. Heat effects for Palermo were much larger than for Santiago, and less harvesting of heat deaths was evident. The estimated heat thresholds were higher in Palermo than in Santiago.

Conclusions:

Our approach provides a flexible and precise method to quantify health effects of both heat and cold exposure at individual lags and to model the overall pattern of the delayed effect.
Analytical active earth thrust on cantilever walls with short heel
Authors: Greco Venanzio R.
Published: December 2008

The use of Rankine’s method is inappropriate for calculating active thrusts in cantilever retaining walls with a short heel because the thrust wedge is interrupted by the wall backface. The use of Coulomb’s approach is preferable, but at present only numerical solutions have been proposed to solve the problem. This paper presents an analytical solution, based on Coulomb’s approach, for evaluating the active thrust on cantilever walls with a short heel subjected to homogeneous backfill with a regular topographic profile and without pore pressure. The solution is given by an algorithm where two equations, one quadratic and the other cubic, are solved in turn, in an iterative procedure that converges rapidly. The distribution of lateral pressure and the position of the point of application of the thrust are also given in analytical terms.
The tensile capacity of bored piles in frictional soils
Authors: Krabbenhoft Sven , Andersen Allan , Damkilde Lars
Published: December 2008

Three series of 10 piles each were installed in two different locations. The lengths of the piles varied from 2 to 6 m and the diameters were 14 and 25 cm. The piles were constructed above the groundwater table using continuous flight augers and the concrete was placed by gravity free fall. The piles were tested to failure in axial uplift and the load–displacement relations were recorded. The results from the tests have been compared with theoretical values based on current design practice and the method proposed by Fleming et al. seems to produce the best match with the test results.
Case study on seismic tunnel response
Authors: Kontoe Stavroula , Zdravkovic Lidija , Potts David M. , Menkiti Christopher O.
Published: December 2008

This paper presents a case study of the Bolu highway twin tunnels that experienced a wide range of damage during the 1999 Duzce earthquake in Turkey. Attention is focused on a particular section of the left tunnel that was still under construction when the earthquake struck and that experienced extensive damage during the seismic event. Static and dynamic plane-strain finite element (FE) analyses were undertaken to investigate the seismic tunnel response at two sections and to compare the results with the post-earthquake field observations. The predicted maximum total hoop stress during the earthquake exceeds the strength of shotcrete in the examined section. The occurrence of lining failure and the predicted failure mechanism compare very favourably with field observations. The results of the dynamic FE analyses are also compared with those obtained by simplified methodologies (i.e., two analytical elastic solutions and quasi-static elastoplastic FE analyses). For this example, the quasi-static racking analysis gave thrust and bending-moment distributions around the lining that differed significantly from those obtained from full dynamic analyses. However, the resulting hoop stress distributions were in reasonable agreement.
Buried high-density polyethylene pipelines subjected to normal and strike-slip faulting — a centrifuge investigation
Authors: Ha Da , Abdoun Tarek H. , O’Rourke Michael J. , Symans Michael D. , O’Rourke Thomas D. , Palmer Michael C. , Stewart Harry E.
Published: December 2008

Permanent ground deformation is arguably the most severe hazard for continuous buried pipelines. This paper presents results from two pairs of centrifuge tests designed to investigate the differences in behavior of buried high-density polyethylene pipelines subjected to normal and strike-slip faulting. The tests results show that, as expected, the pipeline behavior is asymmetric under normal faulting and symmetric under strike-slip faulting. In the case of strike-slip faulting, the soil–pipe interaction pressure distribution is symmetric with respect to the fault. However, in the case of normal faulting, there is a pressure concentration close to the fault trace on the up-thrown side, with much lower soil–pipe interaction pressures at other locations on the pipe. The soil–pipe interaction force versus deformation relationship (i.e., the p–y relationship) was obtained based on the experimental data. The p–y relationships for both the strike-slip and normal faulting cases were also compared with the relationships defined within the American Society of Civil Engineers (ASCE) guidelines. It was found that, for the case of strike-slip faulting, the experimental p–y relationship is generally consistent with the ASCE guidelines. In contrast, the experimental p–y relationship is much softer than that defined by the ASCE guidelines for the normal faulting scenario.
On site characterization and air content evaluation of coastal soils by image analysis to estimate liquefaction risk
Authors: Breul P. , Haddani Y. , Gourvès R.
Published: December 2008

Coastal structures are often submitted to intense wave forcing. In some cases, structures may have stability disorders due to the constant weakening of their foundations and to momentary liquefaction of the sea bed. Studies have shown that if classical geotechnical characterization is a necessity, air content in the soil is also a key parameter for liquefaction evaluation. That is why on site air content measurement and its time variation during a tide period may provide information and help to determine a better understanding of this problem. Unfortunately, this parameter is difficult to measure during investigations. This article presents a technique based on the use of geoendoscopy and automatic image analysis, which makes it possible to characterize coastal soils and to estimate their air content. After a description of the technique, the results obtained on laboratory tests and on a real site are presented.
Boger Fluids
Authors: James David F.
Published: December 2008

A Boger fluid is an elastic liquid with a constant viscosity. Because the viscosity is independent of shear rate or nearly so, elastic effects can be separated from viscous effects in viscoelastic flows because the latter effects can be determined with Newtonian fluids. Boger fluids are dilute polymer solutions generally made with a solvent sufficiently viscous that stresses due to elasticity are measurable. This article closely examines rheological characteristics and reviews flows with Boger fluids, flows for which investigators have found the onset and magnitude of elastic effects through the use of these fluids. Constitutive equations for viscoelastic fluids are evaluated through comparisons to experimental data, including the simple Oldroyd-B equation, which is physically sensible but only marginally accurate. A significant benefit of the introduction of Boger fluids has been the clear identification of a flow instability due to elasticity alone.
Von Kármán's Work: The Later Years (1952 to 1963) and Legacy
Authors: Penner S.S. , Williams F.A. , Libby P.A. , Nemat-Nasser S.
Published: December 2008

In view of the earlier publication in this journal of a biography of Theodore von Kármán by Sears & Sears (1979), which referred to his years in Germany at Göttingen (1908 to 1912) and Aachen (1912 to 1930) and at the Guggenheim Aeronautical Laboratory of the California Institute of Technology (GALCIT) from 1930 to 1952, we restrict our review here to his later years (from 1952 until his death in 1963). We also comment on his scientific legacy and identify representative institutions and outstanding workers whose research continues the von Kármán style of work in the general areas of aerothermochemistry and allied fields.
Uncertainty Quantification and Polynomial Chaos Techniques in Computational Fluid Dynamics
Authors: Najm Habib N.
Published: December 2008

The quantification of uncertainty in computational fluid dynamics (CFD) predictions is both a significant challenge and an important goal. Probabilistic uncertainty quantification (UQ) methods have been used to propagate uncertainty from model inputs to outputs when input uncertainties are large and have been characterized probabilistically. Polynomial chaos (PC) methods have found increased use in probabilistic UQ over the past decade. This review describes the use of PC expansions for the representation of random variables/fields and discusses their utility for the propagation of uncertainty in computational models, focusing on CFD models. Many CFD applications are considered, including flow in porous media, incompressible and compressible flows, and thermofluid and reacting flows. The review examines each application area, focusing on the demonstrated use of PC UQ and the associated challenges. Cross-cutting challenges with time unsteadiness and long time horizons are also discussed.
Right ventricular free wall circumferential strain reflects graded elevation in acute right ventricular afterload
Authors: Cho Eun Joo , Jiamsripong Panupong , Calleja Anna M. , Alharthi Mohsen S. , McMahon Eileen M. , Khandheria Bijoy K. , Belohlavek Marek
Published: December 2008

This study was designed to evaluate the concurrent changes in the right ventricular free wall (RVFW) movement in experimentally induced, acute mild, moderate, and severe right ventricle (RV) afterload conditions. In 14 open-chest pigs (weight 43 ± 4 kg) with preserved pericardia, acute mild (>35 and <50 mmHg), moderate (≥50 and ≤60 mmHg), and severe (>60 mmHg) increases in RV systolic pressure (RVSP) were induced by constriction of the pulmonary artery. At each step, longitudinal, radial, and circumferential strains and strain rates were measured in both the RVFW and the interventricular septum. The mean RVSPs were 31.0 ± 4.3 mmHg at baseline and 41.1 ± 2.7 mmHg during mild, 52.7 ± 3.4 mmHg during moderate, and 61.7 ± 1.6 mmHg during severe afterload conditions. The RVFW circumferential strains showed significant differences among baseline, mild, moderate, and severe afterload conditions (−10.5 ± 3.9, −8.3 ± 3.3, −5.4 ± 2.7, and −7.5 ± 5.3%, respectively, P = 0.008) and had significant linear correlation with RVSP ( r = 0.636, P < 0.001) if the severe condition was excluded. Decrease of the RVFW circumferential strain magnitude is the most distinct response in acute mild and moderate RV afterload that could aid in detection of clinical conditions associated with acutely increasing RV afterload.
Effects of galvanic mastoid stimulation in seated human subjects
Authors: Ghanim Z. , Lamy J. C. , Lackmy A. , Achache V. , Roche N. , Pénicaud A. , Meunier S. , Katz R.
Published: December 2008

The vestibular responses evoked by transmastoid galvanic stimulation (GS) in the rectified soleus electromyogram (EMG) in freely standing human subjects disappear when seated. However, a GS-induced facilitation of the soleus monosynaptic (H and tendon jerk) reflex has been described in few experiments in subjects lying prone or seated. This study addresses the issue of whether this reflex facilitation while seated is of vestibulospinal origin. GS-induced responses in the soleus (modulation of the rectified ongoing EMG and of the monosynaptic reflexes) were compared in the same normal subjects while freely standing and sitting with back and head support. The polarity-dependent biphasic responses in the free-standing position were replaced by a non-polarity-dependent twofold facilitation while seated. The effects of GS were hardly detectable in the rectified ongoing voluntary EMG activity, weak for the H reflex, but large and constant for the tendon jerk. They were subject to habituation. Anesthesia of the skin beneath the GS electrodes markedly reduced the reflex facilitation, while a similar, although weaker, facilitation of the tendon jerk was observed when GS was replaced with purely cutaneous stimulation, a tap to the tendon of the sternomastoid muscle, or an auditory click. The stimulation polarity independence of the GS-induced reflex facilitation argues strongly against a vestibular response. However, the vestibular afferent volley, insufficient to produce a vestibular reflex response while seated, could summate with the GS-induced tactile or proprioceptive volley to produce a startle-like response responsible for the reflex facilitation.
Normal breathing pattern and arterial blood gases in awake and sleeping goats after near total destruction of the presumed pre-Bötzinger complex and the surrounding region
Authors: Krause K. L. , Forster H. V. , Kiner T. , Davis S. E. , Bonis J. M. , Qian B. , Pan L. G.
Published: December 2008

Abrupt neurotoxic destruction of >70% of the pre-Bötzinger complex (preBötzC) in awake goats results in respiratory and cardiac failure (Wenninger JM, Pan LG, Klum L, Leekley T, Bastastic J, Hodges MR, Feroah TR, Davis S, Forster HV. J Appl Physiol 97: 1629–1636, 2004). However, in reduced preparations, rhythmic respiratory activity has been found in other areas of the brain stem (Huang Q, St. John WM. J Appl Physiol 64: 1405–1411, 1988; Janczewski WA, Feldman JL. J Physiol 570: 407–420, 2006; Lieske SP, Thoby-Brisson M, Telgkamo P, Ramierz JM. Nature Neurosci 3: 600–607, 2000; St. John WM, Bledsoe TA. J Appl Physiol 59: 684–690, 1985); thus we hypothesized that, when the preBötzC is destroyed incrementally over weeks, time-dependent plasticity within the respiratory network will result in a respiratory rhythm capable of maintaining normal blood gases. Microtubules were bilaterally implanted into the presumed preBötzC of seven goats. After recovery from surgery, studies were completed to establish baseline values for respiratory parameters. At weekly intervals, increasing volumes (in order 0.5, 1, 5, and 10 μl) of ibotenic acid (IA; 50 mM) were then injected into the preBötzC. All IA injections resulted in an acute tachypnea and dysrhythmia featuring augmented breaths, apneas, and increased breath-to-breath variation in breathing. In studies at night, apneas were nearly all central and occurred in the awake state. Breath-to-breath variation in breathing was greater ( P < 0.05) during wakefulness than during non-rapid eye movement sleep. However, one week after the final IA injection, the breathing pattern, breath-to-breath variation, and arterial blood gases and pH were unchanged from baseline, but there was a 20% decrease in respiratory frequency (f) and CO2 sensitivity ( P < 0.05), as well as a 40% decrease in the ventilatory response to hypoxia ( P < 0.001). In subsequent histological analysis of the presumed preBötzC region of lesioned goats, it was determined that there was a 90 and 92% reduction from control goats in total and neurokinin-1 receptor neurons, respectively. Therefore, it was concluded that 1) the dysrhythmic effects on breathing are state dependent; and 2) after incremental, near total destruction of the presumed preBötzC region, time-dependent plasticity within the respiratory network provides a rhythm capable of sustaining normal arterial blood gases.
Downregulation of Platelet Responsiveness Upon Contact With LDL by the Protein-Tyrosine Phosphatases SHP-1 and SHP-2
Authors: Korporaal Suzanne J.A. , Koekman C. Arnold , Verhoef Sandra , van der Wal Dianne E. , Bezemer Martineke , Van Eck Miranda , Akkerman Jan-Willem N.
Published: December 2008

Objective—

The sensitivity of platelets to aggregating agents increases when low-density lipoprotein (LDL) binds to apolipoprotein E receptor 2′ (apoER2′), triggering activation of p38
MAPK
and formation of thromboxane A
2
. LDL signaling is terminated by PECAM-1 through recruitment and activation of the Ser/Thr protein phosphatase PP2A, but platelets remain unresponsive to LDL when PECAM-1 activation disappears. We report a second mechanism that halts LDL signaling and in addition lowers platelet responsiveness to aggregating agents.

Methods and Results—

After a first stimulation with LDL, platelets remain unresponsive to LDL for 60 minutes, despite normal apoER2′ activation by a second dose of LDL. A possible cause is persistent activation of the tyrosine phosphatases SHP-1 and SHP-2, which may not only block a second activation of p38
MAPK
, PECAM-1, and PP2A by LDL but also seem to reduce aggregation by TRAP, collagen, and ADP.

Conclusion—

These findings reveal that p38
MAPK
phosphorylation and platelet activation by LDL are suppressed by two mechanisms: (1) short activation of PECAM-1/PP2A, and (2) prolonged activation of SHP-1 and SHP-2. Activation of SHP-1 and SHP-2 is accompanied by reduced responsiveness to aggregating agents, which—if present in vivo—would make LDL an aggregation inhibitor during prolonged contact with platelets.
Increased Ca
2+
Sensitivity of the Ryanodine Receptor Mutant RyR2
R4496C
Underlies Catecholaminergic Polymorphic Ventricular Tachycardia
Authors: Fernández-Velasco María , Rueda Angélica , Rizzi Nicoletta , Benitah Jean-Pierre , Colombi Barbara , Napolitano Carlo , Priori Silvia G. , Richard Sylvain , Gómez Ana María
Published: December 2008

Cardiac ryanodine receptor (RyR2) mutations are associated with autosomal dominant catecholaminergic polymorphic ventricular tachycardia, suggesting that alterations in Ca
2+
handling underlie this disease. Here we analyze the underlying Ca
2+
release defect that leads to arrhythmia in cardiomyocytes isolated from heterozygous knock-in mice carrying the RyR2
R4496C
mutation. RyR2
R4496C−/−
littermates (wild type) were used as controls. [Ca
2+
]
i
transients were obtained by field stimulation in fluo-3–loaded cardiomyocytes and viewed using confocal microscopy. In our basal recording conditions (2-Hz stimulation rate), [Ca
2+
]
i
transients and sarcoplasmic reticulum Ca
2+
load were similar in wild-type and RyR2
R4496C
cells. However, paced RyR2
R4496C
ventricular myocytes presented abnormal Ca
2+
release during the diastolic period, viewed as Ca
2+
waves, consistent with the occurrence of delayed afterdepolarizations. The occurrence of this abnormal Ca
2+
release was enhanced at faster stimulation rates and by β-adrenergic stimulation, which also induced triggered activity. Spontaneous Ca
2+
sparks were more frequent in RyR2
R4496C
myocytes, indicating increased RyR2
R4496C
activity. When permeabilized cells were exposed to different cytosolic [Ca
2+
]
i
, RyR2
R4496C
showed a dramatic increase in Ca
2+
sensitivity. Isoproterenol increased [Ca
2+
]
i
transient amplitude and Ca
2+
spark frequency to the same extent in wild-type and RyR2
R4496C
cells, indicating that the β-adrenergic sensitivity of RyR2
R4496C
cells remained unaltered. This effect was independent of protein expression variations because no difference was found in the total or phosphorylated RyR2 expression levels. In conclusion, the arrhythmogenic potential of the RyR2
R4496C
mutation is attributable to the increased Ca
2+
sensitivity of RyR2
R4496C
, which induces diastolic Ca
2+
release and lowers the threshold for triggered activity.
Gap Junction Remodeling and Spironolactone-Dependent Reverse Remodeling in the Hypertrophied Heart
Authors: Qu Jiaxiang , Volpicelli Frank M. , Garcia Luis I. , Sandeep Nefthi , Zhang Jie , Márquez-Rosado Lucrecia , Lampe Paul D. , Fishman Glenn I.
Published: December 2008

Pressure overload is a common pathological insult to the heart and the resulting hypertrophy is an independent risk factor for sudden cardiac death. Gap junction remodeling (GJR) has been described in hypertrophied hearts; however, a detailed understanding of the remodeling process and its effects on impulse propagation is lacking. Moreover, there has been little progress developing therapeutic strategies to diminish GJR. Accordingly, transverse aortic banding (TAC) was performed in mice to determine the effects of progressive pathological hypertrophy on connexin (Cx)43 expression, posttranslational phosphorylation, gap junction assembly, and impulse propagation. Within 2 weeks after TAC, total and phospho-Cx43 abundance was reduced and incorporation of Cx43 into gap junctional plaques was markedly diminished. These molecular changes were associated with progressive slowing of impulse propagation, as determined by optical mapping with voltage-sensitive dyes. Treatment with the aldosterone receptor antagonist spironolactone, which has been shown to diminish sudden arrhythmic death in clinical trials, was examined for its effects on GJR. We found that spironolactone blunted the development of GJR and also potently reversed established GJR, both at the molecular and functional levels, without diminishing the extent of hypertrophy. These data suggest a potential mechanism for some of the salutary electrophysiological and clinical effects of mineralocorticoid antagonists in myopathic hearts.