bluuebunny/crossref_metadata_2025 huggingface dataset:
On the need to publish more case histories
Authors: Kletz Trevor A.
Published: June 2004

Oil and chemical industries are less willing, than in the past, to make reports of accidents public. This is unfortunate because it is in the interest of the whole chemical industry to make accounts of accidents public. Preventative measures, and plant safety budgets, are adopted by the study of accident reports.
Process safety—an integral part of pilot plants
Authors: Dore Jeffrey C.
Published: June 2004

A practical review of how process safety can be integrated into piloting efforts.
Guidelines for safe storage and handling of high toxic hazard materials: A new CCPS Publication
Authors: Drake Elisabeth M. , Croce Paul A.
Published: June 2004

The methodology of the work is discussed. An overview of safety procedures for dealing with high toxic hazard materials is provided.
Stability of acrylic monomers
Authors: Kirch Larry S. , Kargol Joseph A. , Magee Joseph W. , Stuper Wanee S.
Published: June 2004

Certain procedures and tests have been developed to ensure that monomer products are sufficiently stable for manufacturing and handling.
Applications of amine gelling agents in fire technology
Authors: Bannister William W. , Walker Joseph L. , Morehouse Edward T.
Published: June 2004

A novel gelatin system for use in oil spills at sea provides rapid immobilization of liquids upon demand.
The advantages and limitations of adiabatic Dewar calorimetry in chemical hazard testing
Authors: Rogers Richard L.
Published: June 2004

Adiabatic Dewar Calorimeters can be used to measure the temperature time curve of self heating and the induction time of thermal explosions. The important experimental parameters which allow the data to be determined under conditions which directly simulate plant situations are described. The advantages and limitations of the technique are discussed, showing where it can be used to define the process conditions under which uncontrolled reaction could be initiated and to quantify the consequences of such reactions.
Deflagration suppression of high Kst dusts
Authors: Senecal Joseph A.
Published: June 2004

Deflagration suppression is one of several means of explosion protection for process volumes. This paper presents a discussion of some of the variables which influence the final pressure obtained upon suppression of a process deflagration. In particular the discussion focuses on suppression of the deflagrations of fast burning dusts, i.e. dusts with high Kst values. The discussion is amplified using recently obtained data from deflagration and suppression tests on three flammable dusts representing the St‐2 and St‐3 deflagration classes. It is shown that the relationship between post‐suppression pressure and Kst value is not always as expected. The underlying reason for this result relates to differences in the burning characteristics of the subject dusts in the relevant stages of the deflagration.
New knowledge about rotary air locks in preventing dust ignition breakthrough
Authors: Siwek Richard
Published: June 2004

The ignition breakthrough behavior of combustible powders through gaps has ben investigated in the laboratory. Based on these data and on 1:1 experiments with rotary air locks, a nomogram has been set up from which the design parameters for rotary air locks as flame barriers against dust explosions can be read.
Assessing a runaway of a Grignard reaction
Authors: Jones M. C.
Published: June 2004

The venting and control strategies of a Magnesium Grignard formation reaction were assessed by theoretical predictions of the exotherm and the reaction rate, by simple laboratory measurements of the self heat rate, and by Leung's simplified equations and SAFIRE evaluations, based on DIERS methods. SAFIRE computations showed that the 150 mm dia vent was capable of keeping the reactor pressure below its maximum (MAWP) of 860 kPa for the worst‐case exotherm.

The response to this evidence was to increase safety protection in the automatic control strategy, following a quantified fault tree analysis of the worst‐case runaway scenario.
Plant modifications: Maintain your mechanical integrity
Authors: Ramsay Curtis W.
Published: June 2004

Upon initial review of the proposed subject, Plant Modifications and Mechanical Integrity, there is a bit of a disappointment, a lot of the subject matter can easily be placed under the heading “Common Sense.” However, after reviewing successes and failures in this area one finds that common sense may not be as common as one would like. While the successes are much more frequent than the failures, the failures tend to overwhelm the impact of the successes.
Application of twin screw extruders for reactive processing
Authors: Jackson Steven M. , Dreiblatt Adam
Published: June 2004

Reactive extrusion has grown in a few years from a specialized technique for creating experimental materials to the preferred production technique for manufacture of standard polymer systems (ex. polyurethanes) and modification of these systems (ex. grafting). The complexity of the extruder system design has also grown tremendously. The ability of reactive extrusion to produce a myriad of products in a single piece of capital equipment makes it attractive to R&D, manufacturing and financial groups.
Spontaneous fires in insulation
Authors: Britton Laurence G.
Published: June 2004

Combustible liquids may self‐heat in porous insulation yielding smoldering or flaming combustion. In Part I the problem is reviewed and practical measures discussed. Using two‐inch cubes of insulation and a standardized procedure, Spontaneous Ignition Temperatures (SITs) ranging from 55‐184 C are reported for a series of combustible liquids. The application of a self‐heating parameter Z = (AIT)/(AIT‐FP), where AIT is autoignition temperature and FP is closed cup flash‐point (both in Celsius), is examined. The “Z” parameter gives some indication of materials that will self‐heat and those that will evaporate. For Z > 1.61 ignition occurred for all the liquids tested. Evaporation usually occurred for materials with Z < 1.35. It was found that some water‐reactive or peroxide‐forming materials can ignite where only evaporation would be predicted from Z value considerations. An important example of a water‐reactive material is ethylene oxide (EO); the importance of EO insulation fires is that under certain conditions explosive decomposition of EO contained in the equipment can be initiated.

It was previously determined that ethylene oxide reacts in porous, refractory insulations forming low molecular weight polyethylene glycols. The formation rate depends on temperature and the type and condition (particularly water content) of the insulation. Unlike EO the glycols have low volatility and may accumulate over time to several times the mass of some insulations. Under certain conditions the glycols can ignite spontaneously. In Part II experiments carried out to examine this phenomenon are discussed.

Where process temperatures are above the SIT (but below the AIT), cellular glass insulation will minimize the risk of insulation fires. One disadvantage, especially for thermally unstable materials such as EO, is that cellular glass has poor fire endurance properties. The use of a realistic fire endurance test to specify insulation thickness and additional measures such as stainless steel jackets are described.

Alternatives to the use of cellular glass are discussed. When selecting an insulation system, it should be determined whether an insulation fire might occur and the loss potential from such an event should be evaluated.
Forestalling a serious incident: A detective story
Authors: Kaiser Mary A.
Published: June 2004

Two low‐level dust fires and explosions occurred in rotary dryers in one of our east Texas plants. Although there was no significant damage, the potential for safety or loss incidents initiated a concerted effort to determine the cause. The analytical and explosive hazards efforts showed an iron‐adipic compound most probably autooxidized and caused the problem.
Considerations for the safe design of processes using hydrogen peroxide and organics
Authors: Mackenzie John
Published: June 2004

The use of hydrogen peroxide in the chemical processing industry is increasing rapidly, both in volume and types of application. The properties of hydrogen peroxide, which make it such a useful material, can also give rise to serious hazards. This paper reviews some of the ways in which hazards may arise in organic processes using hydrogen peroxide. Some incidents are also described.
HAZOP‐proof ammonia plant: A new way of defining a safe and reliable design
Authors: Grossmann Georg , Fromm Dieter
Published: June 2004

This new technique, which meets interacting design criteria of a 1,800‐MTPD ammonia project, offers special safety features and withstands a detailed HAZOP study.
Results from the model evaluation panel
Authors: Hanna Steven , Chatwin Philip , Chikhliwaia Edul , Londergan Richard , Spicer Thomas , Weil Jeffrey
Published: June 2004

The purpose of this one‐day workshop on hazardous gas model evaluation was to bring together a set of experts to air the various issues on model evaluation, to draft a set of conclusions regarding the state‐of‐the‐art, and to make recommendations for future research.
Dispersion in non‐flat obstructed terrain and advanced modeling techniques
Authors: Meroney Robert N.
Published: June 2004

An expert panel examined the influence of complex terrain, industrial plant obstacles and thermal inhomogeneities on the dispersion of gaseous plumes or aerosols resulting from accidental releases of hazardous materials. Perturbations in transport and dispersion induced by such flow disturbances were estimated. The limitations and accuracies of current numerical and physical modeling techniques were examined. Finally, important unresolved questions concerning the estimation of transport of hazardous materials in the presence of realistic industrial building, storage and transportation environments were identified.
Non‐buoyant puff and plume dispersion modeling issues
Authors: Guinnup Dave
Published: June 2004

This workshop was organized as a discussion group for a panel of dispersion modeling experts aimed at identifying and resolving (to whatever extent possible) the major debatable issues involved in the appropriate application and interpretation of dense gas dispersion models to real and potential scenarios.
Vapor cloud source modeling workshop chairman's report
Authors: Lantzy Ronald J.
Published: June 2004

The objective of the source Modeling Workshop was to discuss our current state of knowledge about source term modeling, and to identify specific areas where research is needed.
Using thermodynamic availability to determine the energy of explosion for compressed gases
Authors: Crowl Daniel A.
Published: June 2004

This paper expands on the work of Crowl [1] by using thermodynamic availability to calculate the energy of explosion for compressed gases.

The results show that thermodynamic availability is a completely general approach, including effects due to chemical reaction and mechanical expansion. For the case of a non‐reactive gas, a general equation is presented to determine the energy of explosion due to mechanical expansion of the gas. The energy determined using availability is much less than the energy determined assuming an isothermal expansion and usually much more than the energy determined assuming an isentropic expansion. Since availability is a state function, the energy determined is independent of the path.
The prediction of spontaneous ignition hazards resulting from the “hot stacking” of process materials
Authors: Griffiths J. F. , Kordylewski W.
Published: June 2004

A change in the normal routine at a factory, which produced a cellulose‐based product, necessitated taking the individual blocks of material from a hot curing process (ca. 200°C) and packing them before they had cooled to an appreciable extent. Spontaneous ignition took place in the packaged material some hours later. Considerable damage to buildings and other losses were incurred. The ambient temperature within the store was not sufficiently high to cause thermal ignition. The problem proved to be a special but not necessarily unusual case in which the onset of ignition was governed by the initial temperature of assembly of the packaged material. These circumstances have been recognized in the fibreboard manufacturing industry for example, such that US legislation requires the cooling of newly manufactured boards below a specified temperature before stacking takes place [1].

We discuss the theoretical background to this type of problem, based on an adaptation of thermal ignition theory with conductive heat transport (Frank‐Kamenetskii conditions). We obtained the appropriate kinetic and thermochemical parameters for exothermic reaction in a cellulosic material in order to apply the theory. We were then able to calculate a maximum packing temperature to expedite safe but efficient storage or transport. The numerical calculations to solve the spatial and time dependent energy conservation equations by use of the finite difference method required a three dimensional grid, set up as 203 mesh points, equivalent to cube‐shaped, packaged material in the practical application. Most of the calculations were performed on a personal computer.
A unique program for integrating health, safety, environment and social aspects into undergraduate chemical engineering education
Authors: Lemkowitz S. M.
Published: June 2004

Over the last fifteen years Delft University of Technology has developed a unique educational program in its undergraduate curriculum. In this program health, safety, environmental and social aspects of chemical engineering are studied explicitly in separate courses while being integrated into the whole of educational and research activities. The program's activities include a required (“dedicated”) third year course, Chemical Risk Management, which covers environment as well as safety. There is also a required first year course, Chemistry and Society/Industrial Orientation, which studies how industries and government react to environmental and safety problems. Another required activity is the Safety Report, which fourth year and graduate students must write and have accepted in order to be allowed to carry out laboratory work. All these activities are closely related to and coordinated with one other. The program, which has been followed by more than two thousand students over the last fifteen years, requires extensive cooperation with industry.
Halon replacement: The law and the options
Authors: Senecal Joseph A.
Published: June 2004

Halons 1301 and 1211 have been employed widely for over 20 years in a broad array of fire and explosion protection applications. These chemicals, however, have been determined to be environmentally unfriendly due to their high ozone depleting potentials. International treaty, national laws and local ordinances have severely limited the future use of these chemicals. Production in the United States will likely come to an effective halt by 1994. A number of alternative chemicals have been suggested as potential replacements for the halons both in total flooding and streaming agent applications. A comparison of the several viable halon alternatives is made including performance, cost and availability. Areas where new applications data are required are noted.
Using the ASTM CHETAH program in chemical process hazard evaluation
Authors: Frurip David J.
Published: June 2004

The CHETAH program has proven to be of great utility in the assessment of reactive chemicals hazards associated with the development of new chemicals and chemical processes. At the Dow Chemical Company, the most frequent use of the program is for the estimation of heats of reaction. Reaction heats are often the single most important parameter in reactive chemicals evaluation since most “worst case” scenarios involve the instantaneous liberation of the reaction energy. Another common use of the program is using CHETAH's unique capability to predict the “explosive” behavior of a material or mixture solely from a knowledge of its molecular structure. Several examples of day‐to‐day use of the program are presented. Current development activity in the ASTM subcommittee which supports CHETAH are discussed. These include new hazard evaluation criteria, better thermodynamic property estimation techniques, and user friendly versions of the program.
From a local Green's function to molecular charge transport
Authors: Albrecht M. , Schnurpfeil A. , Cuniberti G.
Published: June 2004

A local‐orbital basedab initioapproach to obtain the Green's function for large heterogeneous systems is developed. First a Green's function formalism is introduced based on exact diagonalization. Then the self energy is constructed from an incremental scheme, rendering the procedure feasible, while at the same time physical insight into different local correlation contributions is obtained. Subsequently the Green's function is used in the frame of the Landauer theory and the wide band approximation to calculate the electronic transmission coefficient across molecular junctions. The theory is applied to meta‐ and para‐ditholbenzene linked to gold electrodes and various correlation contributions are analyzed. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Disorder effects on the properties of two‐dimensional finite systems in perpendicular magnetic field: the tight binding approach
Authors: Aldea A. , Nitţă M. , Dinu V. , Ţolea M.
Published: June 2004

We review some aspects concerning the disorder effects on the spectral properties of 2D electronic systems with relevance for the transport and orbital magnetism in perpendicular magnetic field. The lattice model and random Anderson disorder are used. The discussion is carried out separately for periodic and hard wall boundary conditions. The degree of localization is evidenced by the calculation of the inverse participation number of the eigenstates of the Hamiltonian and a striking asymmetry of the localization effect of states in the Landau band is reported. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Critical properties in long‐range hopping Hamiltonians
Authors: Cuevas E.
Published: June 2004

Some properties of d‐dimensional disordered models with long‐range random hopping amplitudes are investigated numerically at criticality. We concentrate on the correlation dimension d2 (for d = 2) and the nearest level spacing distribution Pc(s) (for d = 3) in both the weak (bd ≫ 1) and the strong (bd ≪ 1) coupling regime, where the parameter b− d plays the role of the coupling constant of the model. It is found that (i) the extrapolated values of d2 are of the form d2 = cdbd in the strong coupling limit and d2 = d − ad/bd in the case of weak coupling, and (ii) Pc(s) has the asymptotic form Pc(s) ∼ exp (−Adsα) for s ≫ 1, with the critical exponent α = 2 − ad/bd for bd ≫ 1 and α = 1 + cdbd for bd ≪ 1. In these cases the numerical coefficients Ad, ad and cd depend only on the dimensionality. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local distortions and Friedel oscillations in interacting Fermi chains
Authors: Schuster Cosima , Brune Philipp
Published: June 2004

The interplay between disorder and interaction, especially near metal insulator transitions, is a long‐standing question. We investigate in detail single impurities, in particular, the Friedel oscillations induced by them. We study the decay of the Friedel oscillations in the one‐dimensional Heisenberg and Hubbard model analytically using the bosonization technique and numerically using the density matrix renormalization group treatment (DMRG). For the Heisenberg chain, we confirm the predictions of conformal field theory and bosonization for small interaction, but near phase transitions deviations are found in form of vanishing or additional oscillations. For the Hubbard chain, we study the oscillations – in the density as well as in the magnetization – in the spin‐gap, charge‐gap, and Luttinger liquid phase. We find an exponential decay or a very slow algebraic decay of the oscillations in the gapped phases. In the Luttinger liquid phase, we concentrate on the question of logarithmic corrections (which occur also in the isotropic Heisenberg antiferromagnet). Differences in the behavior near a boundary compared to an impurity are pointed out. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Applying simulation and design of experiments to the embedded software testing process
Authors: Lazić Lj , Velašević D
Published: June 2004

This paper presents some original solutions with regard to the deployment of the U.S. Department of Defense Simulation, Test and Evaluation Process (DoD STEP), using an automated target tracking radar system as a case study. Besides the integration of modelling and simulation, to form a model‐based approach to the software testing process, the number of experiments, i.e. test cases, have been dramatically reduced by applying an optimized design‐of‐experiment plan and an orthogonal array‐based robust testing methodology. Also, computer‐based simulation at various abstraction levels of the system/software under test can serve as a test oracle. Simulation‐based (stochastic) experiments, combined with optimized design‐of‐experiment plans, in the case study have shown a minimum productivity increase of 100 times in comparison to current practice without DoD STEP deployment. Copyright © 2004 John Wiley & Sons, Ltd.
Histone deacetylase inhibitors regulate p21WAF1 gene expression at the post‐transcriptional level in HepG2 cells
Authors: Hirsch Calley L , Bonham Keith
Published: June 2004

Histone deacetylase inhibitors (HDIs) are thought to act primarily at the level of transcription inducing cell cycle arrest, differentiation and/or apoptosis in many cancer cell types. Induction of the potent cdk/cyclin inhibitor p21WAF1 is a key feature of this HDI mediated transcriptional re‐programming phenomenon. However, in the current study we report that HDIs are also capable of inducing p21WAF1 through purely post‐transcriptional events, namely increased mRNA stability. These studies highlight our growing appreciation for the complexities of HDI mediated effects and challenge our preconceptions regarding the action of these promising anti‐neoplastics.
On the origin of the electrostatic barrier for proton transport in aquaporin
Authors: Burykin Anton , Warshel Arieh
Published: June 2004

The nature of the electrostatic barrier for proton transport in aquaporins is analyzed by semimacroscopic and microscopic models. It is found that the barrier is associated with the loss of the generalized solvation energy upon moving from the bulk solvent to the center of the channel. It is clarified that our solvation concept includes the effect of the protein polar groups and ionized residues. The nature of the contributions to the solvation barrier is examined by using the linear response approximation. It is found that the residues in the NPA region contribute much less than what would be deduced from calculations that do not consider the protein reorganization. It is clarified that the contributions of different structural or electrostatic elements to the solvation barrier can be established by removing these elements and examining the corresponding effect on the barrier height. Using this definition and “mutating” the NPA residues to their non‐polar analogues establishes that these residues do not provide the major contribution to the solvation barrier.
Cryptic endotoxic nature of Bacillus thuringiensis Cry1Ab insecticidal crystal protein
Authors: Vazquez-Padron Roberto I , de la Riva Gustavo , Agüero Guillermin , Silva Yussun , Pham Si.M , Soberón Mario , Bravo Alejandra , Aı̈touche Abdelouahab
Published: June 2004

Cry1Ab is one of the most studied insecticidal proteins produced by Bacillus thuringiensis during sporulation. Structurally, this protoxin has been divided in two domains: the N‐terminal toxin core and the C‐terminal portion. Although many studies have addressed the biochemical characteristics of the active toxin that corresponds to the N‐terminal portion, there are just few reports studying the importance of the C‐terminal part of the protoxin. Herein, we show that Cry1Ab protoxin has a unique natural cryptic endotoxic property that is evident when their halves are expressed individually. This toxic effect of the separate protoxin domains was found against its original host B. thuringiensis, as well as to two other bacteria, Escherichia coli and Agrobacterium tumefaciens. Interestingly, either the fusion of the C‐terminal portion with the insecticidal domain‐III or the whole N‐terminal region reduced or neutralized such a toxic effect, while a non‐Cry1A peptide such as maltose binding protein did not neutralize the toxic effect. Furthermore, the C‐terminal domain, in addition to being essential for crystal formation and solubility, plays a crucial role in neutralizing the toxicity caused by a separate expression of the insecticidal domain much like a dot/anti‐dot system.
GATA‐3 suppresses IFN‐γ promoter activity independently of binding to cis‐regulatory elements
Authors: Kaminuma Osamu , Kitamura Fujiko , Kitamura Noriko , Miyagishi Makoto , Taira Kazunari , Yamamoto Koh , Miura Osamu , Miyatake Shoichiro
Published: June 2004

The regulatory mechanism by which GATA‐3 suppresses IFN‐γ gene expression was investigated. A reduction of GATA‐3 using RNA interference technology enhanced, whereas overexpression of GATA‐3 suppressed IFN‐γ mRNA expression. IL‐4 expression was reciprocally affected by GATA‐3. GATA‐3‐mediated down‐regulation of IFN‐γ was achieved through the inhibition of its promoter/enhancer activity. Two GATA elements located in the cis‐regulatory elements did not contribute to the suppression of IFN‐γ promoter activity, even though they behaved as binding sites for GATA‐3. The effect of GATA‐3 on IFN‐γ promoter was lost upon removal of the region encompassing −257 to −172. Among several transcription factors putatively interacting with this region, Stat4, which enhanced IFN‐γ promoter activity, was down‐regulated by GATA‐3 at gene transcription level. Although GATA‐3 has the capacity to interact with the cis‐regulatory elements, it suppresses IFN‐γ gene transcription via down‐regulation of Stat4.
Structural analysis of the stalk subunit Vma5p of the yeast V‐ATPase in solution
Authors: Armbrüster Andrea , Svergun Dmitri I , Coskun Ünal , Juliano Sandra , Bailer Susanne M , Grüber Gerhard
Published: June 2004

Vma5p (subunit C) of the yeast V‐ATPase was produced in Escherichia coli and purified to homogeneity. Analysis of secondary structure by circular dichroism spectroscopy showed that Vma5p comprises 64% α‐helix and 17% β‐sheet content. The molecular mass of this subunit, determined by gel filtration analysis and small angle X‐ray scattering (SAXS), was approximately 51 ± 4 kDa, indicating a high hydration level of the protein in solution. The radius of gyration and the maximum size of Vma5p were determined to be 3.74 ± 0.03 and 12.5 ± 0.1 nm, respectively. Using two independent ab initio approaches, the first low‐resolution shape of the protein was determined. Vma5p is an elongated boot‐shaped particle consisting of two distinct domains. Co‐reconstitution of Vma5p to V1 without C from Manduca sexta resulted in a V
1–Vma5p hybrid complex and a 20% increase in ATPase hydrolysis activity.
What controls the uptake of transient tracers in the Southern Ocean?
Authors: Ito Takamitsu , Marshall John , Follows Michael
Published: June 2004

We apply “residual mean” theory of tracer transport, in which eddy transfer plays a fundamental role, to develop scalings and idealized numerical models of the Southern Ocean uptake of transient tracers. The streamline‐averaged numerical model, which represents transport in the meridional plane, captures the observed distributions of CFC‐11, bomb‐Δ14C, and anthropogenic CO2. The model reproduces the observed relationship between CFC‐11 and bomb‐Δ14C and suggests that the upper branch of the residual overturning flow in the Southern Ocean is about 14 Sv, supporting previous inferences based on the observed buoyancy distribution and air‐sea buoyancy fluxes. Scale analysis suggests that the limit of fast air‐sea gas exchange is applicable to CFC‐11, for which the surface concentration is close to equilibrium and cumulative ocean uptake is largely determined by physical transport processes. In the slow gas exchange limit, applicable to bomb‐Δ14C, the surface concentration is far from equilibrium and the cumulative uptake is most sensitive to the parameterization of the gas transfer coefficient. Anthropogenic CO2 falls between those two limit cases and is sensitive to both transport processes and the gas transfer coefficient. Sensitivity studies using the streamline‐averaged model suggest that uncertainties in air‐sea buoyancy fluxes in current climatologies result in significant uncertainty in estimates of Southern Ocean uptake of anthropogenic CO2 based on circulation and biogeochemistry models driven by, or brought into consistency with, the climatological fluxes. This uncertainty is sufficient to explain a significant amount of the spread in a recent model comparison study.
Implications of a nonlinear 40Ar/39Ar age progression along the Louisville seamount trail for models of fixed and moving hot spots
Authors: Koppers Anthony A. P. , Duncan Robert A. , Steinberger Bernhard
Published: June 2004

The Louisville seamount trail has been recognized as one of the key examples of hot spot volcanism, comparable to the classic volcanic Hawaiian‐Emperor lineaments. The published total fusion 40Ar/39Ar data of Watts et al. [1988] showed an astonishing linear age progression, firmly establishing Louisville as a fixed hot spot in the South Pacific mantle. We report new 40Ar/39Ar ages based on high‐resolution incremental heating 40Ar/39Ar dating for the same group of samples, showing a marked increase in both precision and accuracy. One of the key findings in our reexamination is that the age progression is not linear after all. The new data show a significantly decreased “apparent” plate velocity for the Louisville seamount trail older than 62 Ma but confirm the linear trend between 47 Ma and the present day (although based on only three samples over 2150 km). The most recent volcanic activity in the Louisville seamount trail has now been dated at 1.11 ± 0.04 Ma for the most southeastern seamount located at 50°26′S and 139°09′W. These results indicate that the Louisville age progression should be interpreted on the basis of both plate and hot spot motion. In this paper we examine our new results in conjunction with the numerical mantle flow models of Steinberger et al. [2004] that also predict marked deviations from simple linear age progressions. With these models we can achieve a good fit to the geometry of both the Hawaiian and Louisville seamount trails and their age progressions as well as the ∼15° paleolatitudinal shift observed by Tarduno et al. [2003] for the Hawaiian hot spot between 80 and 47 Ma. If the model is restricted to Pacific hot spots only, we can improve the fit to the nonlinear age trend for the Louisville seamount trail by allowing an additional rotation change of the Pacific plate around 62 Ma and by decreasing the initiation age of the Louisville plume from 120 to 90 Ma. This improved model features a significant eastward hot spot motion of ∼5° between 80 and 30 Ma for the Louisville hot spot, which is quite dissimilar to the southward motion of the Hawaiian hot spot during the same time interval, followed by a minor ∼2° latitudinal shift over the last 30 Myr. If hot spot tracks are considered globally, the age trend observed for the oldest part of the Louisville seamount trail does not entirely follow the numerical model predictions. This may indicate some remaining inaccuracies in the global plate circuit, but it may also indicate that the Louisville hot spot experienced a motion somewhat different than in the numerical model: faster in the interval between 62 and 47 Ma but slower before that.
Impact of atmospheric CO2 and galactic cosmic radiation on Phanerozoic climate change and the marine δ18O record
Authors: Wallmann K.
Published: June 2004

A new model is developed and applied to simulate the Phanerozoic evolution of seawater composition (dissolved Ca, Sr, dissolved inorganic carbon, alkalinity, pH, δ18O), marine carbonates (Sr/Ca, 87Sr/86Sr, δ13C, δ18O), atmospheric CO2 and surface temperature. The marine carbonate records (Sr/Ca, 87Sr/86Sr, δ13C) are used to reconstruct changes in volcanic/tectonic activity and organic carbon burial over the Phanerozoic. Seawater pH is calculated assuming saturation with respect to calcite and considering the changing concentration of dissolved Ca documented by brine inclusion data. The depth of calcite saturation is allowed to vary through time and the effects of changing temperature and pressure on the stability constants of the carbonate system are considered. Surface temperatures are calculated using the GEOCARB III approach considering also the changing flux of galactic cosmic radiation (GCR). It is assumed that GCR cools the surface of the Earth via enhanced cloud formation at low altitudes. The δ18O of marine carbonates is calculated considering the changing isotopic composition of seawater, the prevailing surface temperatures and seawater pH. Repeated model runs showed that the trends observed in the marine δ18O record can only be reproduced by the model if GCR is allowed to have a strong effect on surface temperature. The climate evolution predicted by the model is consistent with the geological record. Warm periods (Cambrian, Devonian, Triassic, Cretaceous) are characterized by low GCR levels. Cold periods during the late Carboniferous to early Permian and the late Cenozoic are marked by high GCR fluxes and low pCO2 values. The major glaciations occurring during these periods are the result of carbon cycling processes causing a draw‐down of atmospheric CO2 and a coevally prevailing dense cloud cover at low‐altitudes induced by strong GCR fluxes. The two moderately cool periods during the Ordovician ‐ Silurian and Jurassic ‐ early Cretaceous are characterized by both high pCO2 and GCR levels so that greenhouse warming compensated for the cooling effect of low‐altitude clouds. The very high Jurassic δ18O values observed in the geological record are caused by low pH values in surface waters rather than cold surface conditions.
Supercooled ion temperatures observed in the topside ionosphere at dawn meridian during storm periods
Authors: Su S.‐Y. , Yeh H. C. , Chao C. K. , Heelis R. A.
Published: June 2004

A few rare events of supercooled ion temperature near the magnetic equator at dawn meridian have been observed by the first satellite of the Republic of China, ROCSAT‐1, at 600 km altitude. The ion cooling event occurs within a narrow longitude region where a large density reduction together with a large downward, eastward, and field‐aligned flow is observed. Although ion temperature troughs around the magnetic equator have been observed by many satellites before, and the interhemispheric plasma transport of adiabatic cooling effect for ions near the equator has been modeled to explain the past observations, the current observation enunciates some new facts of the ion cooling effect that have not been reported. First, ion cooling events are observed by ROCSAT at an unprecedented low altitude of 600 km during the solar maximum years of 2000 and 2001. Second, the ion temperature trough is observed, together with a large density reduction and a large downward and eastward drift that were absent in the past observations. Third, the present events are only observed near the dawn meridian during the disturbed periods. Comparing the observational facts with the existing models, we conclude that the model of interhemispheric plasma transport [Bailey et al., 1973; Heelis et al., 1978; Bailey and Heelis, 1980] seems to fit best with the current observations. However, instead of resorting to the quiet time neutral wind to induce the quasi steady state plasma transport as modeled before, a storm time transient dynamical process could have occurred within a limited longitude region where ions at high latitudes are forced to move along the field lines to the dip equator to cause ion cooling observed at 600 km lower than predicted in the model. This storm time ionospheric process could be related to the creation of a westward electric field in the inner magnetosphere near the dawn meridian from a sudden enhancement of the convection field during a disturbed period modeled in the comprehensive ring current model [Fok et al., 2003].
Direct measurement of diurnal polar motion by ring laser gyroscopes
Authors: Schreiber K. U. , Velikoseltsev A. , Rothacher M. , Klügel T. , Stedman G. E. , Wiltshire D. L.
Published: June 2004

We report the first direct measurements of the very small effect of forced diurnal polar motion, successfully observed on three of our large ring lasers, which now measure the instantaneous direction of Earth's rotation axis to a precision of 1 part in 108when averaged over a time interval of several hours. Ring laser gyroscopes provide a new viable technique for directly and continuously measuring the position of the instantaneous rotation axis of the Earth and the amplitudes of the Oppolzer modes. In contrast, the space geodetic techniques (very long baseline interferometry, side looking radar, GPS, etc.) contain no information about the position of the instantaneous axis of rotation of the Earth but are sensitive to the complete transformation matrix between the Earth‐fixed and inertial reference frame. Further improvements of gyroscopes will provide a powerful new tool for studying the Earth's interior.
Variability in chlorophyll and sea surface temperature fronts in the Long Island Sound outflow region from satellite observations
Authors: Stegmann P. M. , Ullman D. S.
Published: June 2004

The spatial and temporal patterns of ocean color (i.e., chlorophyll) and sea surface temperature (SST) fronts in the coastal zone of the northwest Atlantic were studied over a 2‐year period. Chlorophyll images were derived from the Sea‐viewing Wide Field‐of‐view Sensor, while SST data were obtained from the advanced very high resolution radiometer, both flying onboard Earth‐observing satellites. An edge detection algorithm was applied to each of the image sets to identify chlorophyll and thermal fronts. Persistent chlorophyll and thermal fronts co‐occurred in the same vicinity of the inner/middle shelf and were spatially congruent during second (April–May–June) and third (July–August–September) quarters and least coincident during the first (January–February–March). Calculations of the frontogenesis function showed strongest frontogenic tendencies coincident with the chlorophyll and thermal fronts. A major finding of this study was the congruence of both chlorophyll and thermal fronts at a time when the coastal current jet was the most robust, strongly suggesting that it is the presence of this jet that may be a driving force in establishing these fronts. Except for a few months per year, no clear chlorophyll enhancement was observed at thermal fronts.
Observed temperature structure of the atmosphere above Syowa Station, Antarctica (69°S, 39°E)
Authors: Kawahara Taku D. , Gardner Chester S. , Nomura Akio
Published: June 2004

By combining balloonsonde and Na/Rayleigh temperature lidar observations made at Syowa Station (69°S, 39°E) during 2000 and 2001 (a total of 176 observations, 5.9 observations per week), the winter temperature structure from 0 to 110 km is characterized from March to October. The data are also compared with the temperature model of South Pole from Pan and Gardner [2003] which was derived from observations made during the same period as the measurements at Syowa. Although Syowa and South Pole are separated more than ∼2300 km, the temperature structure is quite similar through the year below 30 km. The annual temperature amplitude at Syowa is about 6–7 K smaller than the South Pole data because of the difference in seasonal solar flux variations between the two sites. In spring when the polar vortex weakens and dissipates, the stratospheric temperatures at Syowa increase rapidly as a result of the inflow of warmer air from lower latitudes. In the mesosphere the annual temperature amplitude is anticorrelated with the solar heating because of the strong adiabatic heating and cooling effects associated with the meridional circulation system. The annual temperature amplitude at Syowa is ∼5 K smaller than at South Pole, which is consistent with the smaller adiabatic heating and cooling expected at lower latitudes. The semiannual amplitude at Syowa is 5–7 K larger than at South Pole between 30 and 60 km, and it is 15 K smaller than at South Pole between 80 and 100 km.
Evolutionary algorithms for the optimization of advective control of contaminated aquifer zones
Authors: Bayer Peter , Finkel Michael
Published: June 2004

Simple genetic algorithms (SGAs) and derandomized evolution strategies (DESs) are employed to adapt well capture zones for the hydraulic optimization of pump‐and‐treat systems. A hypothetical contaminant site in a heterogeneous aquifer serves as an application template. On the basis of the results from numerical flow modeling, particle tracking is applied to delineate the pathways of the contaminants. The objective is to find the minimum pumping rate of up to eight recharge wells within a downgradient well placement area. Both the well coordinates and the pumping rates are subject to optimization, leading to a mixed discrete‐continuous problem. This article discusses the ideal formulation of the objective function for which the number of particles and the total pumping rate are used as decision criteria. Boundary updating is introduced, which enables the reorganization of the decision space limits by the incorporation of experience from previous optimization runs. Throughout the study the algorithms' capabilities are evaluated in terms of the number of model runs which are needed to identify optimal and suboptimal solutions. Despite the complexity of the problem both evolutionary algorithm variants prove to be suitable for finding suboptimal solutions. The DES with weighted recombination reveals to be the ideal algorithm to find optimal solutions. Though it works with real‐coded decision parameters, it proves to be suitable for adjusting discrete well positions. Principally, the representation of well positions as binary strings in the SGA is ideal. However, even if the SGA takes advantage of bookkeeping, the vital high discretization of pumping rates results in long binary strings, which escalates the model runs that are needed to find an optimal solution. Since the SGA string lengths increase with the number of wells, the DES gains superiority, particularly for an increasing number of wells. As the DES is a self‐adaptive algorithm, it proves to be the more robust optimization method for the selected advective control problem than the SGA variants of this study, exhibiting a less stochastic search which is reflected in the minor variability of the found solutions.
A two‐directional freeze and thaw algorithm for hydrologic and land surface modelling
Authors: Woo M.‐k. , Arain M. A. , Mollinga M. , Yi S.
Published: June 2004

This paper presents a two‐directional Stefan's solution for computing the freeze and thaw of soil columns. Use of an inverted set of equations to drive the soil freeze‐thaw from the bottom is a significant improvement to the original freeze‐thaw model. Simulations using the algorithm compared well with the 0°C isotherm interpolated from observed data at Arctic, Subarctic and cool temperate sites with different frost conditions that range from permafrost to seasonal frost across a north‐south gradient in North America. The incorporation of explicit freeze‐thaw parameterization in hydrologic and land surface models would enable realistic simulation of soil temperature, soil moisture and runoff/infiltration and hence energy, water and greenhouse gas exchange processes in high latitudes.
Pore scale simulation of solute transport in fractured porous media
Authors: Zhang Dongxiao , Kang Qinjun
Published: June 2004

We investigate the effects of the porosity (and thus permeability) of porous matrix and the fracture aperture on transport in fractured porous media. We do so with detailed lattice Boltzmann simulations on constructed porous media with a single fracture. Both plume spatial moments (the average plume velocity and the dispersion coefficients) and mass transfer coefficients between the facture and the porous matrix are analyzed. It is found that unlike transport in channels or in pure porous media, solute transport in fractured porous media is non‐Gaussian with long tails and with time‐dependent mean plume velocities and non‐Fickian dispersion coefficients. Higher spatial moments may be needed to fully characterize such plumes and the conventional advection‐dispersion equation with upscaled coefficients may be inadequate for describing this anomalous dispersive behavior. The long tailing stems from mass transfer between the fracture and the porous matrix and from the contrast in flow velocities of the two media. It is shown that the mass transfer coefficient is proportional to the matrix diffusivity and inversely proportional to the square of the grain size of the porous matrix. Even for low porosity and low permeability porous matrix whose contribution to flow in the fractured porous media can be neglected, mass transfer between the fractures and the matrix is usually non‐negligible.
Evidence for ‘lock and key’ character in an anti-phosphonate hydrolytic antibody catalytic site augmented by non-reaction centre recognition: variation in substrate selectivity between an anti-phosphonate antibody, an anti-phosphate antibody and two hydrolytic enzymes
Authors: SONKARIA Sanjiv , BOUCHER Guillaume , FLÓREZ-ÁLVAREZ José , SAID Bilal , HUSSAIN Syeed , OSTLER Elizabeth L. , GUL Sheraz , THOMAS Emrys W. , RESMINI Marina , GALLACHER Gerard , BROCKLEHURST Keith
Published: June 2004

The substrate selectivities of an anti-phosphonate and an anti-phosphate kinetically homogeneous polyclonal catalytic antibody preparation and two hydrolytic enzymes were compared by using hapten-analogous and truncated carbonate and ester substrates each containing a 4-nitrophenolate leaving group. Syntheses of the truncated substrates devoid of recognition features in the non-leaving group parts of the substrates are reported. The relatively high kinetic selectivity of the more active anti-phosphonate antibody preparation is considered to depend on a relatively rigid catalytic site with substantial reaction centre specificity together with other important recognition interactions with the extended non-leaving group part of the substrate. In contrast, the less catalytically active, more flexible anti-phosphate antibody exhibits much lower kinetic selectivity for the substrate reaction centre comparable with that of the hydrolytic enzymes with activity much less dependent on recognition interactions with the non-leaving group part of the substrate. The ways in which haptenic flexibility and IgG architecture might contribute to the differential kinetic selectivities are indicated.