bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of carbohydrate carbon sources on the production of constitutive and inducible laccases by Botryosphaeria sp.
Authors: Alves da Cunha Mário A. , Barbosa Aneli M. , Giese Ellen C. , Dekker Robert F. H.
Published: September 2003

The influence of carbohydrates: glucose, fructose, galactose, galacturonic acid, xylose, lactose, sucrose, pectin and inulin, were evaluated as sole carbon source for the production of laccases by the ascomycete, Botryosphaeria sp. Veratryl alcohol, a laccase inducer, was added to culture media to study inducible laccase production on the same carbon sources. Inulinase and pectinase were also produced when Botryosphaeria sp. was grown on inulin, and galacturonic acid and pectin, respectively, and their levels were less in the presence of veratryl alcohol. Botryosphaeria sp. produced constitutive laccases on all carbon sources examined, and veratryl alcohol increased the laccase production on most of carbon sources studied except for inulin and galacturonic acid. Evidence is presented that Botryosphaeria sp. is also pectinolytic.
Beauveria bassiana isolated from engorged females and tested against eggs and larvae of Boophilus microplus (Acari: Ixodidae)
Authors: Fernandes Éverton Kort Kamp , da Costa Gisela Lara , de Souza Edson Jesus , de Moraes Aurea Maria Lage , Bittencourt Vania Rita Elias Pinheiro
Published: September 2003

The purpose of this work was to evaluate the in vitro virulence of three isolates of Beauveria bassiana to eggs and larvae of the tick Boophilus microplus. The fungus tested were isolated from engorged females of B. microplus collected on the field, and identified as Bb28, Bb29 and Bb30. These isolates were evaluated by immersion of eggs and larvae in suspensions with different conidial concentrations: 108, 107, 106 and 105 conidia/ml and compared to the control groups. In the treated eggs, there was a percentage much smaller of hatching than that observed in the controls. The egg hatch was inversely proportional to the conidial concentration. In larval bioassays, all isolates resulted in a higher mortality of larvae compared to the control according to the conidial concentrations/ml, 10 days after treatment inoculation.
Evaluation of a new agar medium containing cetrimide, kanamycin and nalidixic acid for isolation and enhancement of pigment production of Pseudomonas aeruginosa in clinical samples
Authors: Kodaka Hidemasa , Iwata Morihiro , Yumoto Shigeo , Kashitani Fusako
Published: September 2003

A new selective agar medium (CKNA), containing cetrimide 0.3 g/l, kanamycin sulfate 50 mg/l, and nalidixic acid 5 mg/l, was developed for the isolation of Pseudomonas aeruginosa. It was compared to Nalidixic Acid Cetrimide agar (NAC), Pseudomonas Aeruginosa Selective Agar (PASA) and PseudoselTM agar (CET) using 1,148 clinical specimens. The sensitivities rates of P. aeruginosa with CKNA, NAC, PASA, and CET were 88.2%, 81.3%, 79.2%, and 84.0%, respectively. The specificities of CKNA, NAC, PASA, and CET were 99.2%, 98.4%, 99.2%, and 99.7%, respectively.
Enhancing bioremoval of textile dyes by eight fungal strains from media supplemented with gelatine wastes and sucrose
Authors: Abd El‐Rahim Wafaa M. , Moawad Hassan
Published: September 2003

Eight Aspergillus strains were found to be successful in removing textile dyes from liquid media. These fungal strains were grown on medium containing: gelatine wastes and sucrose, as sources of nitrogen and carbon to test the possible speed up of the dyes removing while fungus biomass is building up in the media. The growth of fungal strains ranged from 10 to 110 mg biomass dry weight/100 ml medium. This growth induced high decolorization percentages, which ranged 33–95% within eight days. Two textile dyes Direct brown and Polar red were included in the study. The growth of the fungal strains as well as decolorization percentage of the dyes increased after 5, 6, and 8 days from incubation time with most tested strains. With Direct brown dye the strains number 2, 5, 31 and 37 recorded the highest percentage of decolorization (91, 92, 93 and 95 respectively) after incubation for 6 days. Fungal strains Aspergillus 5 and 31 gave the highest mycelium dry weight being 110 mg. Most of fungal strains induced 86 to 95 percentage of decolorization after 6 days incubation with Polar red dye. The possible toxicity of the remaining supernatant media after fungal biomass removal was tested by Ames test to assess the residual mutagenic agents remaining after dye removal, using three strains of Salmonella typhimurium (TA 1535, TA 1537, TA 1538). The results showed that the toxicity of the dyes, measured by Ames test could be removed by the dye absorption on the fungal biomass.
Isolation and characterization of an indigenous isolate of Dunaliella sp. for β‐carotene and glycerol production from a hypersaline lake in India
Authors: Phadwal Kanchan , Singh P. K.
Published: September 2003

Dunaliella, a green alga grows in a wide range of marine and freshwater habitats such as oceans, brine lakes, salt marshes and salt‐water ditches near the sea, predominantly in water bodies containing more than 10% salt. Sambhar salt lake, Rajasthan (India) was found as one of the natural habitat of Dunaliella sp. The species was isolated and screened for accumulation of β‐carotene and glycerol. It was studied for the growth attributes like total protein, optical density, total chlorophyll, total carotenoid, β‐carotene and glycerol. Under unstressed physico‐chemical conditions the maximum β‐carotene and glycerol observed was 1.15 pg/cell and 94.26 pg/cell respectively. The stress (salt stress (NaCl), high light intensities and continuous light) allowed the alga to accumulate high β‐carotene (approximately 4.21 pg/cell under 118.18 μmole m−2 s−1 of light intensity) without massive reduction in biomass content. This opens up new avenues for exploring this strain for future research and its commercial exploitation.
The diversity of yeasts in the agricultural soil
Authors: Sláviková Elena , Vadkertiová Renata
Published: September 2003

One hundred and eleven yeast strains were isolated from 60 agricultural soil samples. The samples were taken from four various fields located in the southwest of Slovakia. Cryptococcus laurentii, Candida maltosa, Metschnikowia pulcherrima, and Sporobolomyces salmonicolor were the predominant species in the samples collected from all four types of fields. These species represented 78.4–86.6% of the total yeast counts.

The results obtained enabled comparisons to be made between forest and agricultural soil yeast population. We have found out that the yeast population in tilled soils was significantly reduced. The number of yeasts in the tilled soils ranged from 40 to 6.8 × 103 CFU/g soil and the average number reached approximately 1.12 × 103. This number is more than ten times lower in comparison with the forest soils.
Drought indices and their application to East Africa
Authors: Ntale Henry K. , Gan Thian Yew
Published: September 2003

This study analysed and modified (where necessary) the properties of three drought indices: the Palmer drought severity index (PDSI), the Bhalme–Mooley index (BMI) and the standardized precipitation index (SPI). We modified the original PDSI's recursive formula, potential runoff, and Z index, which produced more realistic results than the original PDSI (designed for the USA) for East Africa. We improved the SPI by first using a plotting position formula designed for the Pearson type III (P3) distribution to transform the ‘smoothed’ precipitation data into non‐exceedance probabilities, which we then transformed into standard P3 variates by the regional flood index method. The modified SPI depicted East Africa's drought conditions more accurately than the original SPI. Using the three indices and East Africa as a case example, we identified eight assessment criteria to determine the most appropriate index for detecting drought events on a regional basis. BMI produced results that are highly correlated to those of the modified PDSI, which suggested that precipitation alone could explain most of the variability of East African droughts. Furthermore, among the three indices, SPI is more appropriate for monitoring East African droughts because it is more easily adapted to the local climate, has modest data requirements, can be computed at almost any time scale, provides relatively consistent power spectra spatially, has no theoretical upper or lower bounds, and is easy to interpret. Copyright © 2003 Royal Meteorological Society
Mapping the climate of Puerto Rico, Vieques and Culebra
Authors: Daly Christopher , Helmer E. H. , Quiñones Maya
Published: September 2003

Spatially explicit climate data contribute to watershed resource management, mapping vegetation type with satellite imagery, mapping present and hypothetical future ecological zones, and predicting species distributions. The regression‐based parameter–elevation regressions on independent slopes model (PRISM) uses spatial data sets, a knowledge base and expert interaction to generate grids of climate variables that are compatible with geographical information systems. This study applied PRISM to generate maps of mean monthly and annual precipitation and minimum and maximum temperature for the Caribbean islands of Puerto Rico, Vieques and Culebra over the 1963–95 averaging period. PRISM was run under alternative parameterizations that simulated simpler interpolation methods as well as the full PRISM model. For temperature, the standard PRISM parameterization was compared with a hypsometric method (HYPS), in which the temperature–elevation slope was assumed to be −6.5 °C/km. For precipitation, the standard PRISM parameterization was compared with an inverse‐distance weighting interpolation (IDW). Spatial temperature patterns were linked closely to elevation, topographic position, and coastal proximity. Both PRISM and HYPS performed well for July maximum temperature, but HYPS performed relatively poorly for January minimum temperature, due primarily to lack of a spatially varying temperature–elevation slope, vertical atmospheric layer definition, and coastal proximity guidance. Mean monthly precipitation varied significantly throughout the year, reflecting seasonally differing moisture trajectories. Spatial precipitation patterns were associated most strongly with elevation, upslope exposure to predominant moisture‐bearing winds, and proximity to the ocean. IDW performed poorly compared with PRISM, due largely to the lack of elevation and moisture‐availability information. Overall, the full PRISM approach resulted in greatly improved performance over simpler methods for precipitation and January minimum temperature, but only a small improvement for July maximum temperature. Comparisons of PRISM mean annual temperature and precipitation maps with previously published hand‐drawn maps showed similar overall patterns and magnitudes, but the PRISM maps provided much more spatial detail. Copyright © 2003 Royal Meteorological Society
A human thermal climatology of subtropical Sydney
Authors: Spagnolo J. C. , de Dear R. J.
Published: September 2003

Using a physiologically relevant thermal comfort index (OUT_SET*), an analysis of the week‐by‐week human thermal climate of Sydney was carried out for three levels of metabolic activity. The OUT_SET* index is an outdoor version of the widely used indoor comfort index called the standard effective temperature (SET*) incorporating air and mean radiant temperatures, relative humidity, air velocity, clothing insulation and activity level. The ‘outdoor comfort zone’ for Sydney in terms of OUT_SET* was found from earlier subjective field studies to be in the range 23.8–28.5°C. The analysis indicated that the mid‐summer period (weeks 43 through to 12 in the Southern Hemisphere) was most suitable for sedentary outdoor activities (e.g. watching spectator sport), whereas the mid‐winter period was more suitable for light activities such as walking. Sydney's winter was found to be a very suitable season for tourism in many respects because of (a) low rainfall months, like August, and (b) the ability to undertake light activities while remaining within the outdoor comfort zone. For high metabolic activities during the day, for example the mass participation Sydney City‐to‐Surf fun run, it was found that the threshold limit value for increased risk of heat stress (as defined by ISO 7243, 1989) is exceeded up to 50% of the time during the summer (weeks 50 through to 9 at 3 p.m.) at the 90th percentile probability level. The methods and results of this study should be relevant to end‐users such as architects, engineers, outdoor‐event planners and the tourism industry in general. Copyright © 2003 Royal Meteorological Society
Identification and characterization of sea breeze days in northern France using singular value decomposition
Authors: Bigot S. , Planchon O.
Published: September 2003

Days subject to the development of sea breeze circulations are shown for the months of June and July 2000 in the north of France using an algebraic analysis, the singular value decomposition (SVD). The analysis is performed upon the NOAA‐AVHRR radiometric data (with the surface temperature data from the 22 available stations located in the study area). The geostatistical results show the characteristics of a sea breeze blowing from the English Channel and the North Sea. Meteorological situations with a sea breeze are not the prevailing mode in summer over the northern coast of France, but the sea breeze effect can be shown more than 40 km inland. In addition, the results of the SVD allow one to discriminate different weather systems associated with the thermo‐topographic winds. Copyright © 2003 Royal Meteorological Society
Precipitation characteristics of the Eurasian Arctic drainage system
Authors: Serreze Mark C. , Etringer Andrew J.
Published: September 2003

This study examines characteristics of precipitation over the major watersheds of the Eurasian Arctic drainage system over the period 1960–92. In addition to the Ob, Yenisey and Lena (the three largest drainage systems), we examine the combined Kolyma–Indigirka in eastern Eurasia. Each basin exhibits approximately symmetric mean annual cycles of monthly total precipitation and daily event size, with winter minima and July maxima. These are strikingly similar to the annual cycles of total column water vapour (precipitable water), which fundamentally reflects the control on saturation vapour pressure by temperature. Effective precipitation mechanisms exist in all seasons. However, because of the long distance from strong moisture sources (continentality), precipitation tends to follow the seasonality in column water vapour. An effective contrast is presented for the Iceland sector. Here, the annual cycle of precipitation is tied not to the seasonality in column water vapour, but to the stronger precipitation‐generating mechanisms in winter. Hence, the annual cycles of precipitation and column water vapour in this region oppose each other.

Mean winter precipitation over the Eurasian watersheds is primarily driven by a modest convergence of water vapour. Whereas precipitation peaks in summer, the mean flux convergence exhibits a general minimum (negative in the Ob). Summer precipitation is hence primarily associated with surface evaporation. A strong role of convection is supported from consideration of static stability, the fairly weak spatial organization of precipitation totals and results from prior studies. On daily time scales, the largest basin‐averaged precipitation events, for both summer and winter, are allied with synoptic‐scale forcing. This is seen in relationships with cyclone frequency, and patterns of 500 hPa height, vertical motion and the 700 hPa vapour flux. The relative frequency of four 500 hPa synoptic types captures the basic time series structures of precipitation. Copyright © 2003 Royal Meteorological Society
A regional frequency analysis of United Kingdom extreme rainfall from 1961 to 2000
Authors: Fowler H. J. , Kilsby C. G.
Published: September 2003

Multi‐day rainfall events are an important cause of recent severe flooding in the UK, and any change in the magnitude of such events may have severe impacts upon urban structures such as dams, urban drainage systems and flood defences and cause failures to occur. Regional pooling of 1‐, 2‐, 5‐ and 10‐day annual maxima for 1961 to 2000 from 204 sites across the UK is used in a standard regional frequency analysis to produce generalized extreme value growth curves for long return‐period rainfall events for each of nine defined climatological regions. Temporal changes in 1‐, 2‐, 5‐ and 10‐day annual maxima are examined with L‐moments using both a 10 year moving window and the fixed decades of 1961–70, 1971–80, 1981–90 and 1991–2000. A bootstrap technique is then used to assess uncertainty in the fitted decadal growth curves and to identify significant trends in both distribution parameters and quantile estimates.

There has been a two‐part change in extreme rainfall event occurrence across the UK from 1961 to 2000. Little change is observed at 1 and 2 days duration, but significant decadal‐level changes are seen in 5‐ and 10‐day events in many regions. In the south of the UK, growth curves have flattened and 5‐ and 10‐day annual maxima have decreased during the 1990s. However, in the north, the 10‐day growth curve has steepened and annual maxima have risen during the 1990s. This is particularly evident in Scotland. The 50 year event in Scotland during 1961–90 has become an 8‐year, 11‐year and 25‐year event in the East, South and North Scotland pooling regions respectively during the 1990s. In northern England the average recurrence interval has also halved. This may have severe implications for design and planning practices in flood control. Copyright © 2003 Royal Meteorological Society
Decadal changes in the link between El Niño and springtime North Atlantic oscillation and European–North African rainfall
Authors: Knippertz Peter , Ulbrich Uwe , Marques Filipa , Corte‐Real João
Published: September 2003

The link between El Niño–southern oscillation (ENSO) variability in boreal winter (represented by the NIÑO3 index, i.e. East Pacific sea‐surface temperature anomalies) and the large‐scale circulation and weather conditions over Europe–northwest Africa in spring is explored, considering station reports of precipitation, sea‐level pressure (SLP) anomalies and two North Atlantic oscillation (NAO) indices. It is found that these relations have undergone consistent and simultaneous changes in the 20th century. Three characteristic periods can be identified. During 1900–25 and 1962–87, positive NIÑO3 index values are associated with enhanced precipitation over central Europe and reduced rainfall in southern Europe and northern Africa. The ENSO influence on precipitation over Scotland and Norway is small. The rainfall anomalies can be explained from the advective and dynamical implications of a north–south dipole in SLP correlations (warm ENSO events followed by low pressure in northern Europe and high pressure over the Mediterranean Sea–North Africa). This dipole hardly projects on the commonly used NAO centres (Iceland and Azores/Gibraltar) and thus ENSO–NAO correlations are insignificant. During 1931–56 the NIÑO3 index reveals little influence on precipitation over the Iberian Peninsula and Morocco, but there are large negative correlations with precipitation over Scotland and Norway. This is related to an alteration of the NIÑO3–SLP correlation pattern, which implies high pressure over northern Europe and low pressure over central Europe after warm events, and thus a virtually inverted dipole with respect to the other two periods. The large westward extension of the dipole leads to a significant NAO–NIÑO3 correlation of r = −0.5. These alterations were accompanied by substantial large‐scale circulation changes during the period 1931–56, as revealed by anomalously high pressure and dry conditions over central–western Europe, a change in precipitation‐producing SLP patterns for Morocco and an anomalously low number of positive NAO and NIÑO3 index values. It is left for discussion as to whether the decadal variations described are due to a change in the physics of the teleconnection or to stochastic fluctuations. Copyright © 2003 Royal Meteorological Society
Realignment in the National Football League: Did they do it right?
Authors: Mitchell John E.
Published: September 2003

The National Football League (NFL) in the United States expanded to 32 teams in 2002 with the addition of a team in Houston. At that point, the league was realigned into eight divisions, each containing four teams. We describe a branch‐and‐cut algorithm for minimizing the sum of intradivisional travel distances. We consider first the case where any team can be assigned to any division. We also consider imposing restrictions, such as aligning the AFC (American Football Conference) and the NFC (National Football Conference) separately or maintaining traditional rivalries. We show that the alignment chosen by the NFL does not minimize the sum of intradivisional travel distances, but that it is close to optimal for an alignment that aligns the NFC and AFC separately and imposes some additional restrictions. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 683–701, 2003.
Decentralized admission control of a queueing system: A game‐theoretic model
Authors: Lin Kyle Y.
Published: September 2003

Consider a distributed system where many gatekeepers share a single server. Customers arrive at each gatekeeper according to independent Poisson processes with different rates. Upon arrival of a new customer, the gatekeeper has to decide whether to admit the customer by sending it to the server, or to block it. Blocking costs nothing. The gatekeeper receives a reward after a customer completes the service, and incurs a cost if an admitted customer finds a busy server and therefore has to leave the system. Assuming an exponential service distribution, we formulate the problem as an n‐person non‐zero‐sum game in which each gatekeeper is interested in maximizing its own long‐run average reward. The key result is that each gatekeeper's optimal policy is that of a threshold type regardless what other gatekeepers do. We then derive Nash equilibria and discuss interesting insights. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 702–718, 2003.
Mean sojourn times in multiclass feedback queues with gated disciplines
Authors: Hirayama Tetsuji
Published: September 2003

In this paper, we investigate multiclass feedback queues with gated disciplines. The server selects the stations by a nonpreemptive priority scheduling algorithm and serves customers in the selected station by either a gated FCFS discipline or a gated priority discipline. We take a rather systematic approach to their mean sojourn times. We define conditional expected sojourn times for all customers and derive their expressions from an analysis of busy periods. Since they are shown to be linear in some components of the system states, their steady state mean values can be derived from simple limiting procedures. These mean values can be obtained from a set of linear equations. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 719–741, 2003.
An adaptive dynamic programming algorithm for a stochastic multiproduct batch dispatch problem
Authors: Papadaki Katerina P. , Powell Warren B.
Published: September 2003

We address the problem of dispatching a vehicle with different product classes. There is a common dispatch cost, but holding costs that vary by product class. The problem exhibits multidimensional state, outcome and action spaces, and as a result is computationally intractable using either discrete dynamic programming methods, or even as a deterministic integer program. We prove a key structural property for the decision function, and exploit this property in the development of continuous value function approximations that form the basis of an approximate dispatch rule. Comparisons on single product‐class problems, where optimal solutions are available, demonstrate solutions that are within a few percent of optimal. The algorithm is then applied to a problem with 100 product classes, and comparisons against a carefully tuned myopic heuristic demonstrate significant improvements. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 742–769, 2003.
A specially structured nonlinear integer resource allocation problem
Authors: Bretthauer Kurt M. , Shetty Bala , Syam Siddhartha
Published: September 2003

We present an algorithm for solving a specially structured nonlinear integer resource allocation problem. This problem was motivated by a capacity planning study done at a large Health Maintenance Organization in Texas. Specifically, we focus on a class of nonlinear resource allocation problems that involve the minimization of a convex function over one general convex constraint, a set of block diagonal convex constraints, and bounds on the integer variables. The continuous variable problem is also considered. The continuous problem is solved by taking advantage of the structure of the Karush‐Kuhn‐Tucker (KKT) conditions. This method for solving the continuous problem is then incorporated in a branch and bound algorithm to solve the integer problem. Various reoptimization results, multiplier bounding results, and heuristics are used to improve the efficiency of the algorithms. We show how the algorithms can be extended to obtain a globally optimal solution to the nonconvex version of the problem. We further show that the methods can be applied to problems in production planning and financial optimization. Extensive computational testing of the algorithms is reported for a variety of applications on continuous problems with up to 1,000,000 variables and integer problems with up to 1000 variables. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 770–792, 2003.
Optimal retail assortments for substitutable items purchased in sets
Authors: Agrawal Narendra , Smith Stephen A.
Published: September 2003

We consider the problem of optimizing assortments in a multi‐item retail inventory system. In addition to the usual holding and stockout costs, there is a fixed cost for including any item in the assortment. Customers' preferences for items include both probabilistic substitution patterns and the desire to purchase sets of complementary items. We develop a demand model to capture this behavior, and derive tractable approximations that allow us to formulate the optimization problem as a 0–1 mixed integer linear program. Numerical examples are solved to illustrate key insights into how both complementary and substitute items affect the optimal assortment and the expected profit. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 793–822, 2003.
Exact algorithms for scheduling multiple families of jobs on parallel machines
Authors: Chen Zhi‐Long , Powell Warren B.
Published: September 2003

In many practical manufacturing environments, jobs to be processed can be divided into different families such that a setup is required whenever there is a switch from processing a job of one family to another job of a different family. The time for setup could be sequence independent or sequence dependent. We consider two particular scheduling problems relevant to such situations. In both problems, we are given a set of jobs to be processed on a set of identical parallel machines. The objective of the first problem is to minimize total weighted completion time of jobs, and that of the second problem is to minimize weighted number of tardy jobs. We propose column generation based branch and bound exact solution algorithms for the problems. Computational experiments show that the algorithms are capable of solving both problems of medium size to optimality within reasonable computational time. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 823–840, 2003.
A numerical model for induction heating processes coupling electromagnetism and thermomechanics
Authors: Bay F. , Labbe V. , Favennec Y. , Chenot J. L.
Published: September 2003

This paper presents a mathematical and numerical model developed for coupling the various physical phenomena (electromagnetic, thermal and mechanical) taking place in axisymmetrical induction heating processes. All three electromagnetic, thermal and mechanical models are time dependent and take full account of the electromagnetic and thermal non‐linear effect especially with magnetic materials. The electromagnetic problem is discretized and solved in the workpiece, air and inductors. The heat transfer equation and the mechanical equilibrium equations are solved in the workpiece only, both using a finite element method. The mechanical model can take into account thermoelastic–plastic behaviour for the part. The model has been successfully applied to several cases of induction heating. Comparisons between numerical and experimental results show an excellent agreement. Copyright © 2003 John Wiley & Sons, Ltd.
The meshless finite element method
Authors: Idelsohn Sergio R. , Oñate Eugenio , Calvo Nestor , Del Pin Facundo
Published: September 2003

A meshless method is presented which has the advantages of the good meshless methods concerning the ease of introduction of node connectivity in a bounded time of order n, and the condition that the shape functions depend only on the node positions. Furthermore, the method proposed also shares several of the advantages of the finite element method such as: (a) the simplicity of the shape functions in a large part of the domain; (b) C0 continuity between elements, which allows the treatment of material discontinuities, and (c) ease of introduction of the boundary conditions. Copyright © 2003 John Wiley & Sons, Ltd.
Identification of coating defects in cathodically protected underground pipelines
Authors: Miltiadou Panayiotis , Wrobel Luiz C.
Published: September 2003

Coating defects may occur, for many different reasons, at some points on the surface of a cathodically protected structure. These defects behave anodically and may cause strong localized corrosion. It is possible to identify the position of coating defects by using measured values of the electrochemical potential at some points in the electrolyte or on its surface. To achieve this, an inverse BEM‐based genetic algorithm is developed to identify the position of defects in cathodically protected underground pipelines. The formulation is validated through its application to practical problems involving strongly non‐linear polarization curves, infinite electrolytes, unknown number of defects and measurement noise. Copyright © 2003 John Wiley & Sons, Ltd.
Improved conditioning of infinite elements for exterior acoustics
Authors: Dreyer D. , von Estorff O.
Published: September 2003

An optimized version of the so‐called mapped wave envelope elements, also known as Astley–Leis elements, is introduced. These elements extend to infinity in one dimension and therefore provide an approach to the simulation of exterior acoustical problems in both frequency and time domains. Their formulation is improved significantly through the proper choice of polynomial bases in the direction of radiation. In particular, certain Jacobi polynomials are identified which behave well with respect to conditioning of the system matrices. As a consequence, the size of the finite element discretization may reduce considerably without any loss of accuracy. In addition, the new polynomial bases lead to superior performance of the infinite elements in conjunction with iterative solvers. Copyright © 2003 John Wiley & Sons, Ltd.
A Gaussian sinc‐collocation approach for a whipping cantilever with a follower shear force at its tip
Authors: Reid S. R. , Roy D.
Published: September 2003

A spatial discretization scheme, based on a set of Gaussian sinc functions, is proposed for the temporal projection of a set of partial differential equations (PDEs), describing the non‐linear dynamics of an elastic–plastic hardening–softening (EPHS) cantilever, subjected to a follower shear force at its tip. The dynamics so described correspond to planar whipping of a pipe conveying fluid, ruptured near a right‐angled bend. The constitutive EPHS moment curvature relationship used here follows the earlier work of Reid et al. (Proceedings of the Royal Society of London, Series A 1998; 454: 997–1029). Compared to the more classical Lagrangian polynomial‐based collocation functions, the Gaussian sinc functions have better localization properties. Moreover, for a relatively large number of collocation points, use of such functions does not lead to numerical overflow or underflow problems, often associated with the use of higher order polynomial collocation functions. The spatial discretization leads to a set of non‐linear ordinary differential equations (ODEs) in time, which are in turn integrated via a fourth order adaptive Runge–Kutta scheme. Some numerical results for a cantilever whipping in a plane are presented to further illustrate the present approach. The method is a step forward towards the development of a mesh‐free non‐linear beam element, suitable for dynamic analyses of pipe networks and pipe‐on‐pipe impact problems. Copyright © 2003 John Wiley & Sons, Ltd.
Multiple fully stressed designs of steel frame structures with semi‐rigid connections
Authors: Liu Min , Burns Scott A.
Published: September 2003

A fully stressed design of a frame structure, in which each member is performing to its maximum safe level under at least one loading case, is a common goal in structural design. When multiple fully stressed designs are possible, the designer must make some decisions regarding the desired load path because the outcome of the iterative fully stressed design computation depends upon the initial starting design selected. When steel frame structures are modelled as having semi‐rigid beam‐to‐column connections, the connection flexibility has a significant impact on the nature and diversity of potential fully stressed designs. This paper presents a computational study of how the variety of potential fully stressed designs is affected by connection flexibility. A numerical algorithm, which combines the stress ratio method and Newton's method to avoid problems associated with each method when used alone, is applied to generate sets of distinct fully stressed designs as connection flexibility is varied. It is found that as the connections become increasingly flexible, the variety of fully stressed designs diminishes. Load paths that are efficient with rigid connections are not realizable with semi‐rigid connections because of limited bending moment transfer capacity and, consequently, limited alternate load paths. Copyright © 2003 John Wiley & Sons, Ltd.
On the Pareto optimum sensitivity analysis in multicriteria optimization
Authors: Zhang W. H.
Published: September 2003

To analyse the trade‐off relations among the set of criteria in multicriteria optimization, Pareto optimum sensitivity analysis is systematically studied in this paper. Original contributions cover two parts: theoretical demonstrations are firstly made to validate the gradient projection method in Pareto optimum sensitivity analysis. It is shown that the projected gradient direction evaluated at a given Pareto optimum in the design variable space rigorously corresponds to the tangent direction of the Pareto curve/surface at that point in the objective space. This statement holds even for the change of the set of active constraints in the perturbed problem. Secondly, a new active constraint updating strategy is proposed, which permits the identification of the active constraint set change, to determine the influence of this change upon the differentiability of the Pareto curve and finally to compute directional derivatives in non‐differentiable cases. This work will highlight some basic issues in multicriteria optimization. Some numerical problems are solved to illustrate these novelties. Copyright © 2003 John Wiley & Sons, Ltd.
Differential effects of depolarization on intracellular calcium concentration in wild type and dunce Drosophila neurons
Authors: Alshuaib W.B. , Hasan M.Y. , Cherian S.P. , Fahim M.A.
Published: September 2003

Utilizing Fura 2‐AM fluorescence photometry, intracellular calcium concentration ∥[Ca2+]i) was measured in wild type and dunce cleavage‐arrested Drosophila neurons under resting condition and in response to KCl induced depolarization. Following KCl application, peak [Ca2+]i was greater in dunce (424 ± 29 nM) than in wild type neurons (246 ± 21 nM). Half decay time was shorter in dunce (65 ± 5 sec) than in wild type neurons (84 ± 6 sec). In cadmium‐containing and in calcium‐free external solutions, KCl application did not lead to any changes in [Ca2+]i in wild type and dunce neurons. Thus, the source of increase in [Ca2+]i seems to be Ca2+ influx from outside. Treatment with nifedipine and nimodipine did not affect [Ca2+]i increase in response to KCl application. This indicates that both wild type and dunce neuronal Ca2+ channels are not sensitive to these dihydropyridines. Pretreatment of wild type neurons with dibutyryl cAMP for 1 hour, prior to depolarization by KCl, resulted in peak [Ca2+]i of 369 ± 27 nM which is similar to untreated dunce neurons. The present results suggest that cAMP is implicated in modulating Ca2+ channels leading to enhanced Ca2+ influx in dunce neurons. Calcium extrusion and/or calcium buffering systems are possibly enhanced in the dunce mutant compared to the wild type. This disturbance in homeostatis of cytosolic calcium concentration in dunce neurons may be implicated in defective learning and memory.
Effect of melatonin on β‐amyloid peptide overexpression and memory impairment in a rat AD‐model and the influence of bicuculline
Authors: Xu Haiwei , Fan Xiaotang , Gao Enquan , Wu Xuan , Cao Juan , Li Haidi
Published: September 2003

Melatonin deficiency in cerebrospinal fluid has been postulated to be critical for the development of Alzheimer Disease (AD). As a potent free radical scavengers and antioxidant, melatonin has been proposed to delay or inhibit progression of neurodegenertion in AD. Since the effect of melatonin on Aβ peptide toxicity in the rat oxidative stress model of AD is not fully understood, we observed the effect of melatonin on Aβ protein and APP mRNA in the hippocampus and frontal cortex of AD rats model established by Bennett and found melatonin inhibited the Aβ and APP mRNA. The effect of melatonin could be partly attenuated by pretreatment with the GABA antagonist bicuculline. The results suggest melatonin reduced the Aβ production probably by inhibiting overexpression of APP in the CNS of AD model rats. Maybe these effects of melatonin were influenced by GABA.
A NOS inhibitor aminoguanidine reduces zinc‐induced neuron loss in rat hippocampus
Authors: Gokçe F.M. , Bağirici F. , Kaplan S. , Demir Ş. , Ayyildiz M. , Marangoz C.
Published: September 2003

There are many studies on zinc as a possible cause of neuronal hyperactivity and cell death. The present study was designed to investigate the changes in total pyramidal cell number of rat hippocampus after intracortical zinc sulphate (ZnSO4, 200 μg/kg, i.c.) and a nitric oxide synthase (NOS) inhibitor aminoguanidine (AG) administration. Animals were divided into three groups as control, zinc and the treatment (zinc+AG) groups. Each group was divided into two subgroups, as 7‐day group and 15‐day group. Zinc sulphate was injected intracortically into 2 mm lateral of Bregma. The same volume of saline (2μl) was given to the rats belonging to the control groups. Rats in the third group were given ZnSO4 + AG in the same injection point. Animals in the third group only received 100 mg/kg AG intraperitoneally twice a day for periods of 7 or 15 days. Total pyramidal neuron number was estimated using the optical fractionator method. The total number of pyramidal cells found in the left hippocampus was 653,468 ± 3,452 and 601,860 ± 3,348 in the control groups; 257,968 ± 1,277 and 250,555 ± 1,443 in the zinc groups; 382,519 ± 1,973 and 365,880 ± 2,658 in the treatment groups in 7‐day post treatment and 15‐day post treatment rats, respectively.

These results suggest that zinc has a neurotoxic effect on pyramidal neurons in rat hippocampus (p<0.05) and an inhibitor of nitric oxide synthase, AG, decreases cell loss (p<0.05). This shows that nitric oxide (NO) contributes to this type of neurotoxicity in the rat hippocampus and also suggests a possible therapeutic role for NOS inhibitor in neurodegenerative diseases.
An antitoxidant formulation that induces differentiation of neuroblastoma in culture
Authors: Hancock Amy L. , Nakuci Enkeleda , Nicolosi Robert J. , Shea Thomas B.
Published: September 2003

Neuroblastoma, the most common of all cancers found in children, may arise from a block of differentiation and a resultant continuation of the proliferative state. Neuroblastoma often spontaneously revert by undergoing partial differentiation and ultimate degeneration. A useful therapeutic approach for clinical neuroblastoma may encompass strategies to force neuroblastoma to differentiate. In ongoing studies on neuronal health, we have developed an anti‐oxidant synergy formulation (“ASF”), comprised of α‐tocopherol (vitamin E), sodium pyruvate and phosphatidyl choline, which lessens neurotoxicity and promotes axonal elaboration in cultured neurons. We demonstrate herein that ASF prevents proliferation and promotes differentiation of neuroblastoma in culture, even in the presence of serum, which normally induces rapid neuroblastoma proliferation in culture. These data leave open the possibility that ASF, with proper administration, may foster differentiation, and therefore ultimate degeneration, of neuroblastoma in situ, and may therefore represent a novel approach towards suppression of clinical neuroblastoma.
Micro‐phase‐separation behavior of amphiphilic polyurethanes involving poly(ethylene oxide) and poly(tetramethylene oxide)
Authors: Lee Daewon , Lee Seung‐Heon , Kim Sangcheol , Char Kookheon , Park Jae Hyung , Bae Yoo Han
Published: September 2003

The temperature dependence of thermal, morphological, and rheological properties of amphiphilic polyurethanes was examined with differential scanning calorimetry (DSC), wide‐angle X‐ray scattering (WAXS), small‐angle X‐ray scattering (SAXS), rheological measurements, and Fourier transform infrared spectroscopy. Multiblock (MPU) and triblock (TPU) polyurethanes were synthesized with two crystallizable segments—poly(ethylene oxide) (PEO) as a hydrophilic block and poly(tetramethylene oxide) (PTMO) as a hydrophobic block. DSC and WAXS measurements demonstrated that the microphase of MPUs in the solid state is dominantly affected by the PEO crystalline phase. However, high‐order peaks were not observed in the SAXS measurements because the crystallization of the PEO segments in MPUs was retarded by poor sequence regularity. The microphase in the melt state was induced by the hydrogen bonding between the NH group of hexamethylene diisocyanate linkers and the ether oxygen of PEO or PTMO blocks. As the temperature increased, the smaller micro‐phase‐separated domains were merged into the larger domains, and the liquidlike ordering was eventually disrupted because of the weakening hydrogen bonding. However, the fully homogeneous state of an MPU with a molar ratio of 5/5 PEO/PTMO (MPU55) was not confirmed even at much higher temperatures with both SAXS and rheological measurements. However, the SAXS patterns of TPU showed weak but broad second‐order peaks below the melting temperature of the PEO block. Compared with MPU55, the ordering of the TPU crystalline lamellar stacks was enhanced because of the high sequence regularity and the low hydrogen‐bonding density. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2365–2374, 2003
Gel formation with multiple interunit junctions. II—mixture of different functional molecules
Authors: Tanaka Fumihiko
Published: September 2003

Number‐ and weight‐average molecular weight of condensation polymers formed in the mixture of primary molecules carrying different species of functional groups A and B are derived by the cascade theory. These functional groups are allowed to form multiple junctions of arbitrary multiplicity k. From the weight average, the gel point condition is found to be given by 1 − (fw − 1)(μA,A − 1) − (gw − 1)(μB,B − 1) + (fw − 1)(gw − 1)Dμ = 0, where fw and gw are average functionality of the primary molecules, μαβ the average multiplicity of β groups in the junctions where a path of an α‐group enters, and Dμ ≡ (μA,A − 1)(μB,B − 1) − μA,BμB,A the multiplicity determinant. Possible applications to thermoreversible gelation are suggested. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2413–2421, 2003
Do epoxy–amine networks become inhomogeneous at the nanometric scale?
Authors: Duchet J. , Pascault J. P.
Published: September 2003

Epoxy–amine networks are known to be homogeneous. However, using new analysis tools that allow the observation scale to be reduced to a nanometric level, some authors have stated the opposite. In this work, the network morphology has been studied with atomic force microscopy in the tapping mode as a function of the hardener nature and the stoichiometry of the reactive blend. A very homogeneous epoxy network topography, similar to that of an amorphous thermoplastic, has been obtained. For comparison, a truly heterogeneous network topography, like that of unsaturated thermosets cured by free‐radical mechanisms, has been imaged. For the observation of surfaces on a scale smaller than a nanometer, caution must be taken:(1) the tips must be freshly cleaned so that distortion on the image is prevented and (2) the surfaces must be very flat so that the phase contrast is not influenced significantly by differences in the sample topography. This works gives guidelines on using atomic force microscopy in the tapping mode for epoxy–amine network characterization and discusses epoxy–amine network homogeneity. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2422–2432, 2003
Gel formation with multiple interunit junctions. I—Molecules carrying different functional groups
Authors: Tanaka Fumihiko
Published: September 2003

Number‐ and weight‐average molecular weight of condensation polymers formed by primary molecules carrying different species of functional groups {Ai} (i = 1, 2, …, s) are derived by cascade theory. These functional groups are allowed to form multiple junctions of variable multiplicity k. The gel point condition is found to be given by ∑ wi/|μw,i + 1/∑ fi − 1 = 0, where fi is the number of Ai groups specified by the index i on a primary molecule, wi ≡ fi/∑ fi the number fraction of the species i it carries, and |μw,i the weight average multiplicity of the junctions formed by the groups Ai. The explicit form of the molecular weight distribution function is found for the simplest case of two components. Possible application to thermoreversible gelation is suggested. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2405–2412, 2003