bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Hydrostatic Pressure in Severe Plastic Deformation
Authors: Zehetbauer M.J. , Stüwe H.P. , Vorhauer A. , Schafler E. , Kohout J.
Published: June 2003

The contribution presents several experimental examples which show that the presence of an enhanced hydrostatic pressure—as compared to conventional large deformation modes—is one of the main features of severe plastic deformation (SPD). At the example of systematic high pressure torsion experiments with Cu at room temperature, strength measurements after deformation showed that the onset strains of deformation stages III, IV, and V are not affected by the pressure applied; however, the related onset flow stresses increase by at least 10 % of the values of low pressure torsion, per GPa of pressure increase. During deformation, increases of flow stresses by at least 40 % of the values of low pressure torsion, per GPa of pressure increase, have been found. From comparisons with tests on Ni, the increases appear to grow with the materials melting temperature. For a theoretical explanation of flow stress increases the pressure induced changes of i) the elastic moduli, and ii) the formation energy of lattice defects. While contribution i) is almost negligible, contribution ii) accounts for an increase of flow stress during deformation by about 15 % per GPa of pressure increase. The difference left to experiment has to be attributed to a third contribution, i.e., the pressure specific evolution of the structure. For this contribution, a modification of the model of Zehetbauer and Les[1–3] is introduced which is based on the pressure caused decrease of lattice diffusion. The latter is thought to restrict the diffusion controlled annihilation of dislocations, thus leading to a higher density of vacancies, dislocations and/or grain boundaries causing the higher stress level observed.
Colors of some small figures on colored grounds
Authors: McCamy C. S.
Published: June 2003

Examination of the receptive field structure of the retina suggested looking at small graphic figures of special forms. The luminance distribution called the “Mexican hat function” was approximated by a black dot with a small white dot at its center, called a “tip,” and the inverse function was approximated by a white dot with a small black dot at its center, called a “pit.” Such figures were given the generic name “tippit.” On a dark‐blue ground, tips looked yellow, and on a bright‐yellow ground, pits looked blue. Similarly, a black line with a white center, on a blue ground, and a white line with a black center, on a yellow ground, elicited these effects. On yellow and blue grounds, simple, small colored dots looked more like the color of the ground than when seen as large spots on a neutral gray ground, an effect here called “microspreading.” This effect may be attributable to scattering and blurring, but these processes do not account for the tippit effects. The visual system exaggerates contrast between a large spot and ground, and diminishes contrast between a small dot and ground, but exhibits neither effect on a figure of some intermediate size. Chromatic pit lines exhibit effects obeying laws of additive mixture. It appears that perceptions of these effects are normally repressed. No causal link was sought or established between receptive field theory and the observed effects. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 242–250, 2003; Published online in Wiley InterScience
(www.interscience.wiley.com). DOI 10.1002/col.10159
Chromatic variation of Ishihara diagnostic plates
Authors: Lee David Y. , Honson Matthew
Published: June 2003

Ishihara diagnostic plates of the same design from 10 books (five editions, two books from each) were compared to determine the chromatic and diagnostic variability. The responses of 17 red–green (r‐g) deficient subjects were recorded and compared. Spectrophotometric analysis was also performed on five of these books. The chromaticity coordinates of the colored dots were plotted in the 1931 International Commission on Illumination (CIE) chromaticity diagram in reference to the protan and deutan confusion lines. The relative lightness of the figure compared to the background was calculated as the Weber contrast according to the Smith–Pokorny fundamentals for both protans and deutans. Significant diagnostic variation was found among the r‐g–deficient subjects. The chromaticity coordinates and the relative lightness of the colored dots were also found to have significant variations. We were able to account for many of the diagnostic differences based on the chromaticity and relative lightness variations among the books. Spectrophotometric analysis may provide additional quality control for these plates. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 267–276, 2003; Published online in Wiley InterScience
(www.interscience.wiley.com). DOI 10.1002/col.10161
A test of uniformities in the OSA‐UCS and the NCS
Authors: Indow Tarow
Published: June 2003

In the OSA‐UCS (Optical Society of America–Uniform Color Scales), except for colors on the boundary of the three‐dimensional solid (L, j, g), each color is surrounded by the 12 nearest neighboring colors that are supposed to be perceptually equally different (local uniformity). In the Swedish NCS (Natural Color System), colors are arranged so as to gradually vary in each of the three perceptual attributes: hue, ϕ; blackness, s; and chromaticness, c. The gradual change in an attribute may correspond to change of color difference from one to the next with a constant step (local uniformity). In each of these color‐order systems, the uniformity was tested by a color‐difference formula d̃ based on color‐component differences. When a coordinate is fixed (e.g., j in OSA‐UCS, or c in NCS), d̃ for neighboring pairs turned out fairly constant. However, systematic differences were found between d̃ in one coordinate and d̃ in another coordinate. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 277–283, 2003; Published online in Wiley InterScience
(www.interscience.wiley.com). DOI 10.1002/col.10162
A modified opponent‐colors theory considering chromatic strengths of various hues
Authors: Nayatani Yoshinobu
Published: June 2003

A newly modified opponent‐colors theory is proposed, with the introduction of a concept of relative chroma. Its maximum value is different for different hues and is determined by the chromatic strength of each hue. The newly modified theory is able to clarify the following four points: (1) a contradiction found between color attributes (whiteness, w; blackness, s; and grayness value, gv) for different chromaticness values in the NCS color‐order system; (2) the difference between a constant hue interval and its corresponding perceived hue change (or hue color difference) in the neighborhood of each of the four dual colors raised by Hård et al. (Color Res Appl 1996;21:180–205, 206–220); (3) further strong support of the existence and importance of the reference color gray; and (4) the importance of chromatic strengths of various hues used in color‐appearance studies. The newly modified theory retains most of the merits found in the previously modified one relative to the Hering opponent‐colors theory. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 284–297, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10163
Application of multiflux theory based on scattering by nonspherical particles to the problem of modeling optical characteristics of pigmented paint film: Part II
Authors: Joshi J. J. , Shah H. S. , Mehta R. V.
Published: June 2003

Scattering characteristics of three model systems analogs to red, green, and white pigments containing nonspherical particles are calculated with the T‐matrix method. These scattering parameters are then used to evaluate colorimetric curves of paint films with the multiflux computational technique. Color difference of each system containing different oblate spheroidal‐shaped pigments is calculated with reference to systems containing spherical pigments of equivalent volume. Results show that color‐difference increases for chromatic pigments as shape of pigments deviates from sphericity. Nonabsorbing particle analogs to titanium dioxide behave like spherical particles, though their shape deviates significantly from sphericity. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 308–316, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10165
Finding starting points for Markov chain Monte Carlo analysis of genetic data from large and complex pedigrees
Authors: Luo Yuqun , Lin Shili
Published: June 2003

Genetic data from founder populations are advantageous for studies of complex traits that are often plagued by the problem of genetic heterogeneity. However, the desire to analyze large and complex pedigrees that often arise from such populations, coupled with the need to handle many linked and highly polymorphic loci simultaneously, poses challenges to current standard approaches. A viable alternative to solving such problems is via Markov chain Monte Carlo (MCMC) procedures, where a Markov chain, defined on the state space of a latent variable (e.g., genotypic configuration or inheritance vector), is constructed. However, finding starting points for the Markov chains is a difficult problem when the pedigree is not single‐locus peelable; methods proposed in the literature have not yielded completely satisfactory solutions. We propose a generalization of the heated Gibbs sampler with relaxed penetrances (HGRP) of Lin et al., ([1993] IMA J. Math. Appl. Med. Biol. 10:1–17) to search for starting points. HGRP guarantees that a starting point will be found if there is no error in the data, but the chain usually needs to be run for a long time if the pedigree is extremely large and complex. By introducing a forcing step, the current algorithm substantially reduces the state space, and hence effectively speeds up the process of finding a starting point. Our algorithm also has a built‐in preprocessing procedure for Mendelian error detection. The algorithm has been applied to both simulated and real data on two large and complex Hutterite pedigrees under many settings, and good results are obtained. The algorithm has been implemented in a user‐friendly package called START. Genet Epidemiol 25:14–24, 2003. © 2003 Wiley‐Liss, Inc.
Testing linkage and Gene × Environment interaction: Comparison of different affected sib‐pair methods
Authors: Dizier M.H. , Selinger‐Leneman H. , Genin E.
Published: June 2003

The aim of this study was to compare, under different models of gene‐environment (G × E) interaction, the power to detect linkage and G × E interaction of different tests using affected sib‐pairs. Methods considered were: 1) the maximum likelihood lod‐score (MLS), based on the distribution of parental alleles identical by descent (IBD) in affected sibs; 2) the sum of the MLS (sMLS) calculated in affected sib‐pairs with 2, 1, or 0 sibs exposed; 3) the predivided sample test (PST), which compares the IBD distribution between affected sib‐pairs with 2, 1, or 0 sibs exposed; 4) the triangle test statistic (TTS), which uses the IBD distribution among discordant affected sib‐pairs (one exposed, one unexposed); and 5) the mean interaction test (MIT), based on the regression of the proportion of alleles shared IBD among affected sib‐pairs on the exposure among sib‐pairs. The MLS, sMLS, and MIT allow detection of linkage. However, the sMLS and MIT account for a possible G × E interaction without testing it. In contrast, the PST and the TTS allow detection of both linkage and G × E interaction. Results showed that when exposure cancels the effect of the gene, or changes the direction of this effect (i.e., the protective allele becomes the risk allele), the PST, sMLS, and MIT may provide, under some models, greater power to detect linkage than the MLS. Under models where exposure changes the direction of the effect of the gene, the TTS test may also be more powerful than the other tests accounting for G × E interaction. Under the other models, the MLS remains the most powerful test to detect linkage. However, only the PST and TTS allow the detection of G × E interaction. Genet Epidemiol 25:73–79, 2003. © 2003 Wiley‐Liss, Inc.
Genetic association tests for family data with missing parental genotypes: A comparison
Authors: Whittemore Alice S. , Halpern Jerry
Published: June 2003

We consider three tests for genetic association in data from nuclear families (the Family‐Based Association Test (FBAT) test proposed by Rabinowitz and Laird ([2000] Hum. Hered. 50:211–223), a second test proposed by Rabinowitz ([2002] J. Am. Stat. Assoc. 97:742–758), and the Family Genotype Analysis Program (FGAP) nonfounder or partial score test proposed by Clayton ([1999] Am. J. Hum. Genet. 65:1170–1177) and Whittemore and Tu ([2000] Am. J. Hum. Genet. 66:1329–1340)). We show that each test statistic arises from the efficient score of the family data as the solution to a set of constraints on its null expectation. Moreover, the FBAT and Rabinowitz tests (but not the FGAP test) are locally the most powerful among all tests satisfying their constraints. We used simulations to examine how the three tests perform in situations when their assumptions are violated and the number of families is not huge. We found that the FBAT test tended to have less power than the other two tests, particularly when applied to families in whom all offspring were affected. The Rabinowitz and FGAP tests performed similarly, although the latter tended to extract more information from families containing one typed parent. While none of the tests showed good power to detect rare, recessively acting genes, the Rabinowitz test with a sample variance estimate performed particularly poorly in this case. However, the Rabinowitz test with a model‐based variance had power comparable to that of the FGAP test, and more accurate type I error rates. We conclude that for the situations we considered, the Rabinowitz test with model‐based variance has good power without forfeiting robustness against misspecification of parental genotype probabilities. However, its utility is limited by the lack of a simple algorithm to apply it to families with varying structures and phenotypes. Genet Epidemiol 25:80–91, 2003. © 2003 Wiley‐Liss, Inc.
Assessing accuracy in linkage analysis by means of confidence regions
Authors: Hössjer Ola
Published: June 2003

When statistical linkage to a certain chromosomal region has been found, it is of interest to develop methods quantifying the accuracy with which the disease locus can be mapped. In this paper, we investigate the performance of three different types of confidence regions, with asymptotically correct coverage probability as the number of pedigrees grows. Our setup is that of a saturated map of marker data. We allow for arbitrary combinations of pedigree structures, and treat various kinds of genetic models (e.g. binary and quantitative phenotypes) in a unified way. The linkage scores are weighted sums of the individual family scores, with NPL and lod scores as special cases. We show that the expected length of the confidence region is inversely proportional to the slope‐to‐noise ratio, or equivalently, inversely proportional to the product of the square of the noncentrality parameter and a certain normalized slope‐to‐noise ratio. Our investigations reveal that maximal expected linkage scores can be quite different from estimation‐based performance criteria based on expected length of confidence regions. The main reason is that there is no simple relationship between peak height and peak slope of the mean linkage score. One application of our results is planning of linkage studies: given a certain genetic model, we can approximate the number of pedigrees needed to obtain a confidence region with given coverage probability and expected length. Genet Epidemiol 25:59–72, 2003. © 2003 Wiley‐Liss, Inc.
Linkage analysis with sequential imputation
Authors: Skrivanek Zachary , Lin Shili , Irwin Mark
Published: June 2003

Multilocus calculations, using all available information on all pedigree members, are important for linkage analysis. Exact calculation methods in linkage analysis are limited in either the number of loci or the number of pedigree members they can handle. In this article, we propose a Monte Carlo method for linkage analysis based on sequential imputation. Unlike exact methods, sequential imputation can handle large pedigrees with a moderate number of loci in its current implementation. This Monte Carlo method is an application of importance sampling, in which we sequentially impute ordered genotypes locus by locus, and then impute inheritance vectors conditioned on these genotypes. The resulting inheritance vectors, together with the importance sampling weights, are used to derive a consistent estimator of any linkage statistic of interest. The linkage statistic can be parametric or nonparametric; we focus on nonparametric linkage statistics. We demonstrate that accurate estimates can be achieved within a reasonable computing time. A simulation study illustrates the potential gain in power using our method for multilocus linkage analysis with large pedigrees. We simulated data at six markers under three models. We analyzed them using both sequential imputation and GENEHUNTER. GENEHUNTER had to drop between 38–54% of pedigree members, whereas our method was able to use all pedigree members. The power gains of using all pedigree members were substantial under 2 of the 3 models. We implemented sequential imputation for multilocus linkage analysis in a user‐friendly software package called SIMPLE. Genet Epidemiol 25:25–35, 2003. © 2003 Wiley‐Liss, Inc.
Heat transport characteristics of flexible looped heat pipe under micro‐gravity condition
Authors: Ogushi Tetsurou , Yao Akira , Xu Jason J. , Masumoto Hiromitsu , Kawaji Masahiro
Published: June 2003

This paper presents the heat transport performance of a flexible looped heat pipe (FLHP) with the working fluid of ammonium under micro‐gravity condition. The evaporator of the FLHP has two coaxial wicks. The outer wick is made of PTFE with 1.2µm pore diameter and the inner one is made of polyethylene with 12µm pore diameter. The inside surface of the inner wick is axially grooved. The core of the inner wick is used as liquid reservoir so that reliability of the operation can be enhanced. The experiment revealed that the FLHP performed normally under micro‐gravity condition and had the predicted capillary limit. The FLHP showed good temperature control ability and was like a VCHP in the range of 150 to 240 W heat transfer rate. Liquid behavior observed in the visual module ensured the normal operation of the second wick and inner axial grooves under micro‐gravity condition. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 381–390, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10092
Flashing characteristics in a pipe downstream from a depressurizing tank and temperature fluctuation characteristics at a mixing tee junction with cold water injection
Authors: Shiina Koji , Takahashi Shirou , Asada Yukihiro
Published: June 2003

The flashing characteristics in a pipe downstream from a depressurizing tank were experimentally and analytically investigated on the basis of the transient test and two‐phase flow analysis. The following conclusions were obtained. (1) When the pressure margin of the pump inlet side and the distance to obtain an isothermal condition were sufficient, flashing phenomena did not occur in spite of the decreasing pressure. (2) When the ratio of the cold water injection flow rate to the hot water flow rate Mc/Mh increased, the peak distance of the water temperature fluctuation moved from L/D = 1 to 0, and the maximum water temperature fluctuation ratio was about 40% of the temperature difference between hot and cold water near the mixing tee junction. Because no problem occurred regarding the pipe material thermal fatigue, reliability of the mixing tee junction was assured. (3) Due to suppression of flashing phenomena of the mixing pipe system, the decision diagram on the flashing occurrence was obtained from the test and the analytical results, taking into consideration three factors: the depressurizing ratio in the tank; the cold water injection flow rate due to remaining subcooling; and the delay time of thermal mixing. The simplified analytical equation was used to decrease the cold water injection flow rate by the optimized pipe length between the mixing tee junction and the drain pump. The cold water injection flow rate was minimized when the pipe length was about 15 to 20 times the pipe inner diameter. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 411–429, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10096
Enhancement of shell side forced convective heat transfer in the shell tube‐type heat exchanger using thin plate‐type supports
Authors: Shiina Koji , Nakamura Shozo , Matsumura Seiichi
Published: June 2003

The shell side heat transfer and pressure drop in counterflowing water were experimentally investigated on the basis of the overall heat transfer coefficient. The investigation was intended to identify ways to get higher performance for the cooler in a BWR nuclear power plant. The following three conclusions were reached in the study. (1) Predicted performance of the heat exchanger, using the overall heat transfer coefficient based on the outside area of the tube Ko, indicated an enhancement by 92% compared with the measured performance of the conventional segmental baffle‐type heat exchanger. (2) The tube side pressure drop ΔPt=20 kPa and the shell side pressure drop ΔPs=70 kPa were obtained, and were within the allowable value ΔPa=80 kPa. The shell side pressure drop of the low‐pressure drop spacer could be decreased by 20% as compared with that of the standard spacer. (3) The enhancement constant of the shell side heat transfer using the low‐pressure drop spacer was about 1.2 times as large as that of the standard spacer, regardless of the pumping power. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 455–471, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10097
Effect of fins on forced convection heat transfer around a tube
Authors: Hashizume Kenichi , Matsue Takahiro , Sueoka Yoshiaki
Published: June 2003

Effect of fins on heat transfer around a tube was investigated experimentally. A test tube of 30 mm diameter was installed in a test section of an open‐type wind tunnel as a single tube, or as a center tube in a single tube row and in a tube bundle of staggered layout. Fins made of paper were put on the test tube having certain fin spacing. It was clarified from the experiment that the local heat transfer coefficient around the tube degrades with decreasing fin spacing, especially on the downstream side of the tube, and the minimum fin spacing where the effect of the fin begins to appear is the largest for the single tube and the smallest for the tube bundle. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 445–454, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10098
Prediction of critical heat flux on natural convective boiling in vertical short‐thick tube submerged in saturated liquid
Authors: Liu Zhen‐Hua
Published: June 2003

An experimental and semitheoretical study was carried out for the critical heat flux (CHF) on natural convective boiling in uniformly heated vertical short‐thick tubes and vertical short‐thick annular tubes submerged in saturated liquids. By adapting a mathematical dealing method based on the theoretical formulas of CHF of both the natural convective boiling in vertical narrow‐long tubes and the pool boiling, a simple semitheoretical formula was derived. The new formula expands the prediction range of CHF from pool boiling of vertical plates to very long vertical tubes and agrees well with the data of the tubes, annular tubes submerged in water or other liquids under various pressure conditions. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 402–410, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10103
Study on kinetics of desulfurization reaction by cao particles
Authors: Yan Y. , Peng X.F. , Fu G.G. , Wang B.X.
Published: June 2003

In this paper, TGA was employed in the desulfurization reaction with different CaO particles to investigate the dynamical behavior and the effect of particle size. The changing grain model was revised to describe the reaction kinetics characteristic. The effect of temperature on the reaction was analyzed using scanning electron microscope (SEM) photos of CaO particles. The diffusion coefficient of SO2 in the product layer and the chemical reaction rate constant were acquired through comparison between TGA experimental data and the reaction dynamics equations. It was found that the diffusion coefficient of SO2 in the product layer was proportional to some power of the particle radius and the CaO particles can be depicted by fractal geometry. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 391–401, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10108
A theoretical study of evaporative heat transfer in high‐velocity two‐phase flow of air–water in a small vertical tube
Authors: Yi Jie , Liu Zhen‐Hua , Wang Jing
Published: June 2003

A theoretical study was performed to investigate the evaporative heat transfer of high‐velocity two‐phase flow of air–water in a small vertical tube under both heating conditions of constant wall temperature and constant heat flux. A simplified two‐phase flow boundary layer model was used to evaluate the evaporative heat transfer characteristics of the annular two‐phase flow. The analytical results show that the gravitational force, the gas–liquid surface tension force, and the inertial force are much smaller than the frictional force and hence can be neglected for a small tube. The evaporative heat transfer characteristics of the small tube with constant wall temperature are quite close to those of the small tube with constant heat flux. The mechanism of the heat transfer enhancement is the forced convective evaporation on the surface of the thin liquid film. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 430–444, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10110
Reinforced concrete structures – shall concrete remain the dominating means of corrosion prevention?
Authors: Rostam S.
Published: June 2003

The acknowledged serious deterioration of reinforced concrete structures due to chloride induced corrosion has been the main fuel for research and development of very dense and impermeable concrete, so‐called high performance concrete (HPC). This development has dominated concrete research up through the 80'ies and 90'ies. The results have technically been successful. However, the practical use of such concretes on site have often posed serious difficulties, resulting in at times very low performance concrete structures although HPC was specified. The discrepancy between concrete quality reached in the laboratory, what is being specified in the design and what can realistically be achieved on site is seldom in balance. Alternative means of more or less reliable means of corrosion prevention, often based on organic materials, have during recent years been developed to protect our inorganic concrete and reinforcement. However, a highly reliable means of corrosion prevention has been the introduction of stainless steel reinforcement, which is available with dimensions and strengths directly interchangeable with ordinary carbon steel reinforcement. It has been proven that stainless steel and carbon steel can be in metallic contact when cast into concrete, without causing galvanic corrosion. This seems, for the present, to be like an unexpectedly simple and highly reliable solution to the corrosion problems. As exemplified, this technology is rapidly gaining momentum in highly corrosive environments – and concretes being much more robust to execution can now take over from HPC.
Evolution of reinforcement corrosion due to climatic variations
Authors: Andrade C. , Castillo A.
Published: June 2003

Concrete moisture is the most significant parameter with respect to its durability, however the data on moisture content in real‐size structures are scarce in contrast to the numerous literature published on laboratory experiments. The majority of laboratory tests have been performed in chambers with controlled hydrothermal regime, in general to enable the concrete to reach equilibrium and steady‐state conditions. However, real weather induces permanent non‐steady state situations due to the evolution of temperature and climatic events as snowing or raining.

Present paper discusses the effect of climatic events on the hydrothermal performance of concrete and their influence on reinforcement corrosion process. Concerning the moisture level, the degree of saturation, SW, and not the internal relative humidity has been identified to be the controlling parameter of the corrosion process. The psychometric chart and the SW‐RH plots are very suitable to study the hydrothermal behaviour. With respect to the corrosion parameters, corrosion potential, resistivity and corrosion rates, they are very influenced by temperature in a complex manner. The temperature is the main factor influencing the degree of saturation in sheltered conditions while rain and snow are so, in unsheltered ones. In opposition, however, what can be expected, climates with higher temperatures are less aggressive than colder ones, except when rain periods are produced during the hotter periods.
Zum rückseitigen kathodischen Korrosionsschutz einseitig korrodierender Stahlbetonbauteile – Modellversuche und numerische Berechnungen
Authors: Raupach M. , Warkus J.
Published: June 2003

Der kathodische Korrosionsschutz ist ein weltweit verbreitetes Verfahren zum Schutz korrosionsgefährdeter Bewehrung in Stahlbetonbauteilen. Dabei wird durch eine äußere Spannung, die zwischen der Bewehrung und einer inerten Anode angelegt wird oder über galvanische Anoden, ihr elektrochemisches Potential in negative Bereiche verschoben, in denen der Stahl kathodisch reagiert. Bei einseitig unzugänglichen Bauteilen (Stützwände, Tunnel, etc.) oder unter Abdichtungen ist es aus baupraktischen Überlegungen oft wünschenswert, die Anode an der abgewandten Seite der gefährdeten Lage anzubringen. In diesem Zusammenhang soll durch am Institut für Bauforschung der RWTH Aachen zur Zeit laufende Untersuchungen der Fragestellung nachgegangen werden, ob ein Schutz der abgewandten Lage möglich ist oder durch die Abschirmung der näher an der Anode liegenden Bewehrung verhindert wird. Erste Ergebnisse aus diesen Untersuchungen zeigen, dass der Schutz von der Rückseite unter bestimmten Bedingungen möglich ist. Weiterhin wird überprüft, ob durch geeignete numerische Modellierungen das Verhalten der Probekörper unter variablen Randbedingungen berechnet werden kann.
Langzeitverhalten feuerverzinkter Bewehrungsbänder für Bewehrte Erde Bauwerke
Authors: Nürnberger U.
Published: June 2003

Bei Bewehrte Erde Bauwerken sind • durch die Wahl spezifischer nichtbindiger Böden, • durch Maßnahmen zur Verhinderung des Eindringens von Fremdsalzen • und durch die Wahl einer mind. 100 μm dicken Zinkschicht Maßnahmen getroffen worden, die einen langjährigen Korrosionsschutz der Bewehrungsbänder sicherstellen. Es ist nahezu auszuschließen, daß es in baupraktisch relevanten Zeiträumen zu einem korrosionsbedingten Versagen der Bänder kommt.
Temporärer Korrosionsschutz von Spannstählen in unverpressten Hüllrohren
Authors: Isecke B. , Mietz J. , Schütt K.
Published: June 2003

Spannstähle können während der Verarbeitung auf Baustellen korrosiven Belastungen ausgesetzt sein, die zu einer Gefährdung der Spannstähle durch wasserstoffinduzierte Spannungsrisskorrosion führen können. Um zu überprüfen, ob eine Spülung der Spannkanäle mit vorgetrockneter Luft ausreicht, die Spannstähle im unverpressten Zustand gegen Korrosion hinreichend zu schützen, sind Versuche unter praxisähnlichen Bedingungen an einem Spannbetonbalken durchgeführt worden. Die Ergebnisse zeigen, dass diese Maßnahme die Korrosion im Hüllrohr vollständig verhindert und somit eine interessante Alternative zum Korrosionsschutz mit filmbildenden Mitteln (Inhibitoren) bildet.
Wasserstoffabsorption in alkalischen Elektrolyten
Authors: Moersch J.
Published: June 2003

Es wurden Wasserstoffpermeationsversuche durchgeführt, um die Mechanismen der Wasserstoffabsorption in alkalischen Elektrolyten bei niedrigen Bedeckungsgraden der Stahloberfläche mit Wasserstoff zu klären. Die zu variierenden Parameter waren dabei der Sauerstoffgehalt (von Sauerstoffarmut bis Sauerstoffsättigung) und der pH‐Wert (9, 11 und 13) der Elektrolyte. Es wurden die Wasserstoffad‐ und ‐absorptionsraten und die Wasserstoffaktivitäten bestimmt.
Non destructive determination of the free chloride content in cement based materials
Authors: Elsener B. , Zimmermann L. , Böhni H.
Published: June 2003

A non‐destructive chloride sensitive sensor element for use in cement based porous materials is presented. The sensor element determines the activity of the free chloride ions in solutions and in porous cement based materials such as cement paste, mortar or concrete. The calibration in synthetic pore solution showed a response according to Nernst law over three decades of chloride concentration. The sensor element has shown excellent reproducibility and long term stability. The sensor element has been used to monitor the chloride uptake into mortar specimens. The results show a good agreement between the free chloride content determined by the sensor and by pore water expression. Applications in monitoring of reinforced concrete structures and their limitations are discussed.
Einfluss der Umgebungsbedingungen auf das Instandsetzungsprinzip W bei Korrosion infolge Karbonatisierung des Betons
Authors: Weydert R.
Published: June 2003

Das Instandsetzungsprinzip W – Absenken des Wassergehaltes des Betons – ist Teil der Richtlinie für Schutz und Instandsetzung von Betonbauteilen des Deutschen Ausschusses für Stahlbeton. Bei der Instandsetzung wird nach geeigneter Vorbehandlung der Korrosionsschäden die Betonoberfläche mit einer geeigneten Beschichtung versiegelt. Hierdurch soll der Wassergehalt des Betons soweit abgesenkt werden, dass Korrosion am Stahl zum Stillstand kommt. In Untersuchungen wurden Eignung und Wirksamkeit unterschiedlicher Beschichtungssysteme im Rahmen von Instandsetzungsversuchen aufgezeigt.
Prenatal diagnosis for Epidermolysis bullosa: a study of 144 consecutive pregnancies at risk
Authors: Pfendner Ellen G. , Nakano Aoi , Pulkkinen Leena , Christiano Angela M. , Uitto Jouni
Published: June 2003

Epidermolysis bullosa (EB) is a group of inherited disorders characterized by increased skin fragility, resulting in blisters and erosions after minor trauma. Mutations in 10 structural genes expressed in the cutaneous basement membrane zone have been reported. The DebRA Molecular Diagnostics Laboratory at Jefferson Medical College has performed 144 DNA‐based prenatal diagnoses since 1993 in families at risk for recurrence of the most severe forms of EB, including the recessive dystrophic EB (RDEB), junctional EB (JEB), EB with pyloric atresia (EB‐PA), and EB simplex (EBS). A mutation‐detection strategy using either conformation‐sensitive gel electrophoresis (CSGE) or denaturing high‐performance liquid chromatography (dHPLC) scanning analysis, followed by nucleotide sequencing, was applied to most cases with DEB and to all JEB, EB‐PA, and EBS families. For some RDEB families, linkage analysis was performed, either alone when the inheritance pattern was clear or in combination with one mutation. Among the 144 prenatal diagnoses, 63 were for RDEB, 69 for JEB, 6 for EB‐PA, and 6 for EBS. Twenty‐eight normal, 73 heterozygous carrier, and 28 affected RDEB, JEB, and EB‐PA pregnancies were reported in these recessively inherited diseases. Two affected and four normal pregnancies were predicted in dominantly inherited EBS. Among the 144 pregnancies, 9 were terminated without confirmation, 13 cases were lost to follow‐up, and 6 pregnancies are ongoing. There were 6 families with inconclusive results due either to recombination events between flanking markers, absence of informative markers for one allele, or lack of sample from the previously affected child. There were three discordant results, one that was explained by maternal contamination of the chorionic villus sample and two that were unresolved. Overall, the availability, relative ease, and over 98% success rate make molecular DNA‐based prenatal diagnosis a viable option for EB families at risk. Copyright © 2003 John Wiley & Sons, Ltd.
A classification of pregnancy losses after invasive prenatal diagnostic procedures: an approach to allow comparison of units with a different case mix
Authors: Nanal Rashmi , Kyle Phillipa , Soothill Peter W.
Published: June 2003

Objective

Pregnancy loss rates after prenatal invasive procedures such as amniocentesis (Amnio), chorionic villous sampling (CVS) and fetal blood sampling (FBS) vary with an underlying indication for the procedure and due to different background risk of miscarriage. Loss rates need to be quantified and available for counselling. We developed a classification of pregnancy losses that will help in calculating procedure‐related pregnancy loss rates and allow comparison between units with a different case mix.

Methods

The procedure‐related pregnancy loss rate was obtained by subtracting the losses in pregnancies with known lethal conditions and those occurring more than two weeks after the procedure from total pregnancy losses.

Results

Out of 436 CVSs, there were 18 losses. Of these, 14 had a known lethal condition and 3 occurred after 2 weeks of CVS. In only one case, there was no known lethal abnormality and the loss occurred within 2 weeks. Thus, the total pregnancy loss rate was 4.1% and the procedure‐related loss rate was 0.23% (95% CI; 0.0061–1.28). The procedure‐related loss rates for Amnio 0.7% (95% CI; 0.2–1.8) and FBS 1.19 (95% CI; 0.14–4.23) were calculated in a similar way.

Conclusions

We present a method of recording pregnancy loss after prenatal invasive procedures, which would be useful for benchmarking comparison between units and pre‐procedural counselling. Copyright © 2003 John Wiley & Sons, Ltd.
Sirenomelia, the mermaid syndrome—detection in the first trimester
Authors: Schiesser Monika , Holzgreve Wolfgang , Lapaire Olav , Willi Nils , Lüthi Hans , Lopez Roberto , Tercanli Sevgi
Published: June 2003

The sirenomelia sequence with fusion, rotation, hypotrophy or atrophy of the lower limbs in combination with severe urogenital and gastrointestinal malformations is a rare and usually lethal disorder.

We present the case of a 28‐year‐old woman, who was referred to our department because of an intraabdominal cystic structure in the 9th week of gestation. Subsequent scans confirmed the diagnosis of a sirenomelia sequence with the fusion of the lower extremities without fusion of the bones according to Stocker I classification. The size of the intraabdominal cyst decreased during follow‐up. After counseling, termination of pregnancy was induced. The postmortem X‐ray confirmed the ultrasound diagnosis.

The exact etiological mechanism of this malformation is still unknown. An early alteration of the embryological vascular network damaging the caudal mesoderm is thought to lead to arrested development of the lower limbs and other affected organs. The cyst we saw in the 9th week might fit with this theory, either as an expression of the complex malformation of the lower abdomen or as the sonographic appearance of necrosis. Copyright © 2003 John Wiley & Sons, Ltd.
Amniotic fluid human chorionic gonadotrophin and alpha‐fetoprotein levels in pregnancies conceived after assisted reproduction
Authors: Hui P. W. , Lam Y. H. , Tang M. H. Y. , Ng E. H. Y. , Yeung W. S. B. , Ho P. C.
Published: June 2003

Objectives

To study the alteration in the second‐trimester maternal serum levels of human chorionic gonadotrophin (hCG) and alpha‐fetoprotein (AFP) in pregnancies conceived after assisted reproduction.

Methods

We compared the amniotic fluid hCG and AFP concentrations of 45 pregnancies with fresh embryo transfer and 25 pregnancies with frozen–thawed embryo transfer with 269 spontaneous pregnancies. Wilcoxon rank‐sum test was used for analysis.

Results

The median amniotic fluid hCG MoM in pregnancies conceived after frozen–thawed embryo transfer was significantly increased to 1.41 compared to 1.00 (p = 0.01) in naturally occurring pregnancies and 0.96 (p = 0.049) in pregnancies after fresh embryo transfer. Further analysis showed that this was only observed in frozen embryos fertilized by conventional insemination with MoM of 1.59. The AFP MoMs were similar among the groups.

Conclusions

The observed raised amniotic fluid hCG level in IVF‐FET pregnancies may reflect the elevated maternal serum level in these pregnancies. Further studies should be directed towards exploring the underlying pathophysiology. Copyright © 2003 John Wiley & Sons, Ltd.
Perinatal findings and molecular cytogenetic analysis of trisomy 16q and 22q13.3 deletion
Authors: Chen Chih‐Ping , Lin Shuan‐Pei , Chern Schu‐Rern , Shih Shin‐Lin , Lee Chen‐Chi , Wang Wayseen , Liao You‐Wei
Published: June 2003

Objectives

To present the perinatal findings and molecular cytogenetic analysis of a case with concomitant trisomy 16q and 22q13.3 deletion of paternal origin.

Case and Methods

A 24‐year‐old pregnant woman was referred at 30 weeks' gestation for suspected fetal abnormalities. Sonographic examination revealed decreased fetal movement, dolicocephaly, an asymmetric skull, and intrauterine growth restriction. Prenatal karyotyping was suggested but was declined. A female baby was delivered vaginally at 39 weeks' gestation with a body weight of 2180 g. The neonate presented generalized hypotonia with frequent apneic episodes and died at 1.5 months of age. Additional physical abnormalities included epicanthal folds, ptosis, frontal bossing with an enlarged metopic suture, bitemporal narrowing, hypertelorism, epicanthal folds, a pointed chin, micrognathia, prominent ears with preauricular pits, and clinodactyly. The karyotype from peripheral blood lymphocytes was 46,XX,der(22)t(16;22)(q12.1;q13.3)pat. The microdeletion at 22q13.3 was investigated by fluorescent in situ hybridization (FISH) analysis using the LSI DiGeorge/VCFS region/ARSA dual color DNA probe and the 22q telomeric probe, of which only the latter was able to detect the subtle deletion. Molecular analysis using polymorphic microsatellite markers indicated that the breakpoint at 22q13.31 was located between loci D22S1171 (present) and D22S1168 (absent).

Conclusion

The use of LSI DiGeorge/VCFS region/ARSA dual color DNA probes to examine distal 22q would miss some subtle terminal deletions of 22q13. However, the use of 22q telomeric probes would detect these minute deletions. Fetuses having trisomy 16q and 22q13.3 deletion may prenatally manifest decreased fetal movement, dolicocephaly, an asymmetric skull, and intrauterine growth restriction and postnatally present generalized hypotonia with frequent apneic episodes. Copyright © 2003 John Wiley & Sons, Ltd.
The influence of IVF, multiple gestation and miscarriage on the acceptance of genetic amniocentesis
Authors: Elimian Andrew , Demsky Marcy , Figueroa Reinaldo , Ogburn Paul , Spitzer Alan R. , Gerald Quirk J.
Published: June 2003

Objectives

To determine the effect of in vitro fertilization (IVF), multiple gestation, and history of unkaryotyped miscarriage on the acceptance of genetic amniocentesis.

Methods

We studied women expected to be at least 35 years of age at the estimated date of delivery without family history of chromosomal abnormalities or fetal structural anomalies. The influence of IVF, multiple gestation, and history of miscarriage on the acceptance rate of genetic amniocentesis was evaluated. Chi‐square test and logistic regression were used for analysis.

Results

In singleton pregnancies, the acceptance rate of genetic amniocentesis was 70.7% (58/82) in the IVF group compared to 77.9% (1837/2356) (P = 0.14) in the women who conceived spontaneously. The corresponding values in multiple gestation pregnancies were 71.1% (37/52) and 62.9% (34/54) respectively (P = 0.41). There was no difference in the acceptance rate of amniocentesis between singletons (70.7%) and multiple gestations (71.1%) after IVF (P = 0.96), while in women who conceived spontaneously, the acceptance rate of 78% in singletons was significantly higher than the acceptance rate of 63% in multiple gestations (P = 0.008). Adjusting for confounding variables, women with multiple gestations were about 40% less likely to accept genetic amniocentesis (OR = 0.63, 95% CI = 0.39–1.00, P = 0.05), while women with a history of miscarriage were about 17% less likely to accept genetic amniocentesis (OR = 0.83, 95% CI = 0.68–1.00, P = 0.05). Adjusting for multiple gestation and previous miscarriage, IVF was not independently associated with acceptance of genetic amniocentesis (OR = 0.84, 95% CI = 0.54–1.29, P = 0.42).

Conclusions

There is no difference in the acceptance rate of genetic amniocentesis among women with IVF pregnancies compared with those who conceive spontaneously, after adjusting for multiple gestation and previous miscarriage. Unlike women who conceive spontaneously, the decision to accept amniocentesis appears not to be influenced by the presence of multiple gestation in women with IVF pregnancies. Copyright © 2003 John Wiley & Sons, Ltd.
SHIFT AND SCALE COUPLING METHODS FOR PERFECT SIMULATION
Authors: Corcoran J.N. , Schneider U.
Published: June 2003

We describe and develop a variation on a layered multishift
coupler due to Wilson that uses a slice sampling procedure to
allow one to obtain potentially common draws from two different
distributions. Our main application is coupling sample paths
of Markov chains for use in perfect sampling algorithms. The
coupler is based on slicing density functions and we describe
a “folding” mechanism as an attractive alternative
to the accept/reject step commonly used in slice sampling
algorithms. Applications of the coupler are given to storage
models and to auto-gamma distribution sampling.
DISPERSION-TYPE VARIABILITY ORDERS
Authors: Belzunce Félix , Hu Taizhong , Khaledi Baha-Eldin
Published: June 2003

Dispersion-type orders are introduced and studied. The new
orders can be used to compare the variability of the underlying
random variables, among which are the usual dispersive order
and the right spread order. Connections among the new orders
and other common stochastic orders are examined and investigated.
Some closure properties of the new orders under the operation
of order statistics, transformations, and mixtures are derived.
Finally, several applications of the new orders are given.
HYPERGEOMETRIC GROUP TESTING WITH INCOMPLETE INFORMATION
Authors: Bar-Lev Shaul K. , Stadje Wolfgang , Van der Duyn Schouten Frank A.
Published: June 2003

We studied several group testing models with and without
processing times. The objective was to choose an optimal group
size for pooled screening of a contaminated population so as
to collect a prespecified number of good items from it with
minimum testing expenditures. The tested groups that were found
to be contaminated were used as a new sampling population in
later stages of the procedures. Since testing may be
time-consuming, we also considered deadlines to be met for the
testing process. We derived algorithms and exact results for
the underlying distributions, enabling us to find optimal
procedures. Several numerical examples are given.
LARGE DEVIATIONS BOUNDS FOR FACE-HOMOGENEOUS RANDOM WALKS
IN THE QUARTER-PLANE
Authors: Hordijk Arie , Popov Nikolai
Published: June 2003

In this article, we analyze the large deviations bounds for
the nonergodic face-homogeneous random walk in the positive
quadrant. Under some condition the value of the local rate function
for the path identically equal to zero is found, and an explicit
expression is derived for it. This makes the computation of
its value possible for specific stochastic networks. Some numerical
examples are given.