bluuebunny/crossref_metadata_2025 huggingface dataset:
Cribra orbitalia and cribra cranii in Roman skeletal remains from the Ravenna area and Rimini (I–IV century AD)
Authors: Facchini F. , Rastelli E. , Brasili P.
Published: March 2004

Cribra orbitalia and cribra cranii are considered good indicators of the health and nutritional status of ancient populations, as their presence is often associated with chronic acquired anaemia. The distribution of these lesions in two Roman samples from the Ravenna area and Rimini was considered as a measure of health in relation to their respective environments. Enamel hypoplasia was also assessed as it is symptomatic of childhood physiological stresses such as malnutrition, infectious diseases, physiological traumas, and the like. The differential analysis suggests that the lesions observed are due to chronic acquired anaemia, probably caused by a poor diet, worm infestation, infections and parasitic diseases. Copyright © 2004 John Wiley & Sons, Ltd.
Large‐scale extrusion processing and characterization of hybrid nylon‐6/SiO2nanocomposites
Authors: García Monserrat , van Vliet Gerhard , ten Cate Mattijs G. J. , Chávez Francisco , Norder Ben , Kooi Bart , van Zyl Werner E. , Verweij Henk , Blank Dave H. A.
Published: March 2004

Solution impregnations, pulltrusion and film stacking are widely used methods to prepare thermoplastic composite materials. Extruders are used to melt the polymer and to incorporate fibers into the polymer in order to modify physical properties. In this article, the compounding of colloidal silica nanoparticles filled polyamide‐6 (PA‐6) is achieved using a twin‐screw extruder, which has a significant market share due to its low cost and easy maintenance. The experiments were performed at 250 rpm and the bulk throughput was 6 kg h−1with a pump pressure of 30 bars. The composites were characterized with nuclear magnetic resonance (NMR), wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). As determined by WAXD, the PA‐6 showed higher amounts ofγ‐phase when compared to other synthesis methods such asin situpolymerization. TEM pictures showed that the silica particles aggregated nevertheless, upon addition of 14% (w/w) silica the E‐modulus increased from 2.7 to 3.9 GPa indicating that an effective mechanical coupling with the polymer was achieved. The behavior, illustrated with dynamic mechanical analysis (DMA) curves, indicated that in general when a filled system is compared to unfilled material, the values of the moduli (E′ and E″) increased and tanδdecreased. Determination of molecular mass distribution of the samples by means of size exclusion chromatography (SEC) coupled to a refractive index (RI), viscosity (DV) and light scattering (LS) detector revealed that the addition of silica did not decrease the average molecular weight of the polymer matrix, which is of importance for composite applications. Copyright © 2004 John Wiley & Sons, Ltd.
Compaction of thick composites: Simulation and experiment
Authors: Shin Daniel D. , Hahn H. Thomas
Published: March 2004

A realistic process simulation model for heat transfer and compaction along the bleeder‐composite assembly was developed. Two case studies were presented with this model in which one took advantage of variable resin properties while the other used constant values. The predicted results were then experimentally validated with 228‐ply and 380‐ply AS4/3501‐6 graphite/epoxy laminates cured under one‐dimensional resin flow condition. The model‐experiment correlation was quite good for the 228‐ply laminate although results with variable resin properties predicted better through‐the‐thickness temperature distribution than with constant resin properties. The model also predicted faster compaction rate because the compressibility model appeared to predict higher fiber volume fraction for given effective stress. As for the 380‐ply laminate, notable deviations were observed for both the temperature and compaction predictions. The discrepancies appeared to have manifested from inaccurate resin property and compressibility models.
Structure characterization and conductive performance of polypyrrol‐molybdenum disulfide intercalation materials
Authors: Wang Tingmei , Liu Weimin , Tian Jun , Shao Xin , Sun Dacheng
Published: March 2004

Two types of polypyrrol/molybdenum disulfide nanocomposites were prepared by means of in situ polymerization of the intercalated monomers. The nanocomposites were characterized by means of powder X‐ray diffraction, Fourier transformation infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. The charge transport properties of the nanocomposites were determined by four‐probe electrical conductivity measurement of pressed pellet samples. The relationship between the electrical conductivity at various temperatures and conformation of the polypyrrol/ molybdenum disulfide nanocomposites were investigated. Results indicated that polypyrrol took two kinds of conformation in the interlayer of MoS2. The electrical conductivity of the intercalation nanocomposites at room temperature was dependent on the conformation and stereo‐regular characteristics of the polypyrrol molecules in the MoS2 layers, it was mainly determined by the number of the active charge carriers in polypyrrol at −60°C. The intercalation of polypyrrol into MoS2 led to an increase in the electrical conductivity by six orders of magnitude.
Prenatal diagnosis of congenital Chagas' disease (American trypanosomiasis)
Authors: Okumura Maria , Aparecida dos Santos Vera , Camargo Mário E. , Schultz Regina , Zugaib Marcelo
Published: March 2004

The prenatal diagnosis of congenital transmission of Chagas' disease in a pregnant woman with the indeterminate form of the disease is reported. Sonography revealed fetal hydrops at 31 weeks' gestation. Anti‐Trypanosoma cruzi IgM and IgG antibodies were negative in the fetal blood sampled by cordocentesis, but T. cruzi trypomastigotes were found in its buffy coat. Owing to anemia, in utero exchange transfusion was undertaken, but fetal demise ensued. Labor was induced and a stillborn infant weighing 2030 g was delivered. The pathological examination revealed placentitis and meningoencephalitis, myocarditis and splenitis in the stillborn fetus. Amastigotes were found in the myocardium, brain and placenta. Copyright © 2004 John Wiley & Sons, Ltd.
Sonographic findings in Beckwith–Wiedemann syndrome related to H19 hypermethylation
Authors: Le Caignec C. , Gicquel C. , Gubler M. C. , Guyot C. , You M. C. , Laurent A. , Joubert M. , Winer N. , David A. , Rival J. M.
Published: March 2004

Beckwith–Wiedemann syndrome (BWS) is an overgrowth syndrome associated with congenital malformations and tumour predisposition. BWS results from variable mutations or epigenetic modifications of imprinted genes in the 11p15 chromosomal region. We present a fetus with mild general overgrowth and bilateral enlarged echogenic kidneys with loss of the corticomedullary differentiation in which prenatal diagnosis of BWS was suspected. The rest of the fetal anatomy and the amniotic fluid volume appeared normal. After termination of the pregnancy, molecular analysis confirmed the diagnosis of BWS by showing an isolated hypermethylation of the H19 gene. Copyright © 2004 John Wiley & Sons, Ltd.
Introduction of the QF‐PCR analysis for the purposes of prenatal diagnosis in Bulgaria—estimation of applicability of 6 STR markers on chromosomes 21 and 18
Authors: Andonova Silvia , Vazharova Radoslava , Dimitrova Violeta , Mazneikova Valentina , Toncheva Draga , Kremensky Ivo
Published: March 2004

Objective

The aim of our study was to estimate the observed heterozygosity and informativeness of 6 STR markers on chromosomes 18 and 21 in the Bulgarian population. We have evaluated the applicability of these markers used from other investigators for QF‐PCR prenatal diagnosis of the most common autosomal aneuploidies in Bulgaria.

Methods

DNA samples (n = 486) were extracted from different fetal tissues (amniotic fluid cells, chorionic villus samples, and fetal tissue after abortions). PCR amplifications of 4 STR markers located on chromosome 21 (D21S11, D21S1411, D21S1270, and D21S1440) and 2 on chromosome 18 (D18S535 and D18S51) were performed. They were analysed on an automated sequencer, and the allele dosage ratios were calculated.

Results

The results indicate the selected markers as highly informative for our population and suitable for QF‐PCR prenatal diagnosis in Bulgaria. All samples with trisomy 21 (n = 8), trisomy 18 (n = 4) and triploidy (n = 1) were correctly detected by our analysis. Thus, no false‐negative results were observed.

Conclusion

QF‐PCR analysis could be an applicable alternative in prenatal and postnatal diagnosis in cases with a strong suspicion for particular autosomal aneuploidies (including chromosomes 21, 18, and 13) in small countries with limited resources like Bulgaria. Copyright © 2004 John Wiley & Sons, Ltd.
Prenatal diagnosis of 47,XX,der(15)t(15;16)(q13;p13.2)
Authors: Santolaya‐Forgas Joaquin , De Leon Juan , Cameron Powell Wm. , Tonk Vijay
Published: March 2004

A case of prenatally detected partial trisomy 15 and 16 is reported. Amniocentesis was performed at 14 weeks' gestation because a 6‐mm nuchal translucency was detected on a dating ultrasound evaluation. Karyotype from amniocytes was suspect of an aberration concerning a marker chromosome. FISH analysis demonstrated that this marker chromosome was a der(15). A maternal chromosomal rearrangement t(15;16)(q13;p13.2) was confirmed. At birth, the proband was severely hydropic and had dysmorphic features, which included hypertelorism, micrognathia, incomplete separation of the maxilla and mandible, hyperflexed hands with overlapping fingers, hyposegmented right lung, and a single umbilical artery. Copyright © 2004 John Wiley & Sons, Ltd.
Culture of endothelial cells isolated from maternal blood using anti‐CD105 and CD133
Authors: Elicha Gussin Hélène A. , Sharma Arun K. , Elias Sherman
Published: March 2004

Objectives

We hypothesized that fetal cells in maternal blood that do not respond to hematopoietic culture conditions represent endothelial cells. We investigated whether endothelial progenitor cells of fetal origin may be selected from maternal blood on the basis of their expression of CD133 or CD105 and expanded in culture.

Methods

Peripheral blood mononuclear cells from 16 pregnant women (gestational age: 11 to 24 weeks) were labeled with magnetic beads coupled to anti‐CD133 or anti‐CD105. Selection of labeled cells was performed using MACS. Resulting CD133+, CD105+, and CD133−/CD105− cell fractions were placed in culture in conditions favoring endothelial cells for 7 days (positive fractions) to 30 days (depleted fractions). Cells from women carrying male fetuses were analyzed by conventional PCR (SRY primers) for detection of male cells.

Results

Expansion of cells isolated from all subjects occurred in each of the cell fractions. No PCR products consistent with the presence of male cells were detected in women carrying male fetuses.

Conclusion

CD133+ and CD105+ cells isolated from maternal blood can be expanded in vitro under endothelial conditions. These cells appear to be of maternal, rather than fetal, origin. Copyright © 2004 John Wiley & Sons, Ltd.
Effect of erucamide and silica loadings on COF behavior of POP multilayer films in repetitive testing
Authors: Janorkar Amol V. , Hirt Douglas E. , Wooster Jeffrey J.
Published: March 2004

Erucamide is incorporated into polymer films to reduce their coefficient of friction (COF). Such COF reduction is important in packaging lines where the performance of the film in contact with rollers can be governed by the frictional characteristics of the film. This research explores the COF behavior of multilayer films with either polyolefin plastomer (POP) or linear low‐density polyethylene (LLDPE) as the skin layer. Film‐on‐metal COF testing was performed repetitively with the same piece of film to investigate the extent of COF change with the number of runs for cast and blown films. Results showed that the COF of the film increased with the number of runs and plateaued at a higher steady state value. Complementary analysis conducted with atomic force microscopy (AFM) revealed that initially erucamide was removed from the film surface exposing the bare polymer film to the metal plate, but as more runs were performed the erucamide crystals were smeared over the film surface re‐covering the previously exposed film surface. Several combinations of slip and antiblock (AB) loadings were used to study their effects on the steady state COF obtained from repetitive testing on blown films. Results showed that the steady state COF decreased with the addition of both slip and AB, except for the lowest chosen loadings of 1250 ppm slip and 3000 ppm AB.
School psychologist assessment practices in the evaluation of students referred for social/behavioral/emotional problems
Authors: Shapiro Edward S. , Heick Patrick F.
Published: March 2004

The current study examined the assessment strategies school psychologists used in their everyday assessment routine in the evaluation of students referred for social/behavioral/emotional problems. A stratified, random, national sample of 1,000 members of the National Association of School Psychologists were sent surveys; 667 completed surveys were returned, and 648 were included in the current study (64.8%). Findings indicated that, although measures of intelligence, achievement, and perceptual‐motor skills continue to remain a part of the assessment process, structured interviews, direct observation, and behavior rating scales and checklists also are frequently used methods of assessment. In addition, the majority of experienced practitioners indicated that their use of behavioral assessment had increased and that it was valuable in linking assessment to intervention. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 551–561, 2004.
Including fathers in school psychology literature: A review of four school psychology journals
Authors: Greif Jennifer L. , Greif Geoffrey L.
Published: March 2004

It is well documented that fathers have a significant influence on their children's success in school. To examine the ways in which fathers have been represented in school psychology literature, the authors searched over 1,000 recent articles published in four leading U.S. school psychology journals (Psychology in the Schools, School Psychology Review, School Psychology Quarterly, and the Journal of School Psychology) for content on fathers. Fathers were included substantially in nine articles and were the primary focus of only one other article. Reasons for the lack of information on fathers and suggestions for increasing the focus on fathers in school psychology literature are discussed. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 575–580, 2004.
Polymerization of substituted phenylacetylenes with a novel, water‐soluble Rh–vinyl complex in water
Authors: Kanki Keiji , Nakazato Atsushi , Nomura Ryoji , Sanda Fumio , Masuda Toshio
Published: March 2004

A novel, water‐soluble Rh complex, (nbd)Rh[PPh2(m‐NaOSO2C6H4)] [C(Ph)CPh2] (1) was synthesized by the reaction of [(nbd)RhCl]2, Ph2P(m‐NaOSO2C6H4) and Ph2CC(Ph)Li, whose structure was determined by NMR and IR spectroscopies. The Rh catalyst 1 induced the polymerization of phenylacetylene (PA) in water to give two kinds of polymers; one was soluble in organic solvents such as tetrahydrofuran (THF) and CHCl3, and the other was insoluble in common organic solvents. The polymerization of sodium p‐ethynylbenzoate (p‐NaOCO‐PA) homogeneously proceeded with 1 in water at 60 °C to give the polymer in high yield. Poly(p‐NaOCO‐PA) was treated with 1 N HCl and then reacted with (CH3)3SiCHN2 to obtain poly(p‐MeOCO‐PA). The methyl‐esterified polymer was insoluble in THF and CHCl3, which suggests that the formed poly(p‐MeOCO‐PA) has cis–cisoidal structure. The polymer obtained from the polymerization of [p‐CH3(OCH2CH2)2O2CC6H4]CCH with 1 in water was soluble in methanol, ethanol, and THF, and partly soluble in water. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2100–2105, 2004
Synthesis of a water‐soluble diblock copolymer of polysulfonic diphenyl aniline and poly(ethylene oxide)
Authors: Hua Fengjun , Ruckenstein Eli
Published: March 2004

We report the synthesis of a water‐soluble diblock copolymer composed of polysulfonic diphenyl aniline (PSDA) and poly(ethylene oxide) (PEO), which was prepared by reacting an amine‐terminated PSDA and tosylate PEO (PEO‐Tos). First, a HCl‐mediated polymerization of sulfonic diphenyl aniline monomer with the formation of HCl‐doped PSDA was carried out. After its neutralization and reduction, a secondary amine‐functionalized PSDA was obtained. Second, PEO‐Tos was synthesized via the tosylation of the monohydroxyl PEO methyl ether with tosylol chloride. Diblock copolymers with various PEO segment lengths (PSDA‐b‐PEO‐350 and PSDA‐b‐PEO‐2000) were obtained with PEO‐350 [number‐average molecular weight (Mn) = 350] and PEO‐2000 (Mn = 2000). The prepolymers and diblock copolymers were characterized by Fourier transform infrared spectroscopy, NMR, mass spectrometry, and ultraviolet–visible light. They had relatively low conductivities, ranging from 10−6 to 10−3 S/cm, because of the withdrawing effect of the sulfonic group as well as the steric effects of the bulky aromatic substitutuents at the N sites of the polyaniline backbone and of the PEO block. These polymers were self‐doped, and an intermolecular self‐doping was suggested. The external doping was, however, more effective. The self‐doping induced aggregation in water among the PSDA backbones, which was also stimulated by the presence of hydrophilic PEO blocks. Furthermore, the electrical conductivities of the diblock copolymers were strongly temperature‐dependent. PSDA‐b‐PEO‐2000 exhibited about one order of magnitude increase in conductivity upon heating from 32 to 57 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2179–2191, 2004
Luminescent poly(phenylene vinylene) derivatives with m‐terphenyl or 2,6‐diphenylpyridine kinked segments along the main chain: Synthesis, characterization, and stimulated emission
Authors: Karastatiris Panayiotis , Mikroyannidis John A. , Spiliopoulos Ioakim K. , Fakis Mihalis , Persephonis Peter
Published: March 2004

Two new poly(phenylene vinylene)s containing m‐terphenyl or 2,6‐diphenylpyridine kinked units along the main chain were synthesized and were used as luminescent and laser materials. They were prepared from Heck coupling of 2,5‐didodecyloxy‐1,4‐divinylbenzene with 4,4″‐dibromo‐3′‐phenyl‐m‐terphenyl or 2,6‐di(4‐bromophenyl)‐4‐phenylpyridine. The kinked units along the main chain caused a partial interruption of the conjugation leading to emission at a shorter wavelength as compared with poly(p‐phenylene vinylene). The polymers presented blue‐green emission in solution and green‐yellow emission in the solid state with photoluminescence maxima at 465–497 and 546–550 nm, respectively. Polymer containing 2,6‐diphenylpyridine segments emitted at a longer wavelength than that containing m‐terphenyl and displayed higher quantum yields in solution (0.61 and 0.40, respectively). The influence of the solvent and polymer concentration on the photoluminescence characteristics was investigated. The photoluminescence properties of protonated polymer containing 2,6‐diphenylpyridine segments were investigated both in solution and in film. Amplified spontaneous emission and tunable laser action were also obtained from the two polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2214–2224, 2004
Load and depth sensing indentation as a tool to monitor a gradient in the mechanical properties across a polymer coating: A study of physical and chemical aging effects
Authors: Boersma A. , Soloukhin V. A. , Brokken‐Zijp J. C. M. , de With G.
Published: March 2004

Load and depth sensing indentation has been used to characterize the elastic modulus and hardness of various polycarbonate films. This analytical technique is shown to be extremely suitable for the determination of gradients in these mechanical properties. Furthermore, it is demonstrated that such a gradient exists over a length of micrometers in chemically aged polycarbonate, but it is virtually absent in physically aged polycarbonate. From these results, it is concluded that, although the first 100 nm cannot be probed, physical aging occurs homogeneously throughout the bulk of the sample. However, chemical aging starts at the surface and moves progressively into the bulk of the material. From the study of these films, it appears that for the interpretation of these measurements, knowledge about the amount of creep occurring during the measurements and about the mechanical properties of the substrate on which these films are applied is needed. Creep can be measured with the same indenter through the application of a constant load for a period of time. Load and depth sensing indentation appears to be a powerful method for studying the physical and chemical aging of polymers. It is especially valuable for coatings and films for which conventional tensile testing is problematic. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1628–1639, 2004
Mutual influence of the morphology and capillary rheological properties in nylon/glass‐fiber/liquid‐crystalline‐polymer blends
Authors: Zheng Xuejing , Zhang Jun , He Jiasong
Published: March 2004

Nylon‐6/glass‐fiber (GF)/liquid‐crystalline‐polymer (LCP) ternary blends with different viscosity ratios were prepared with three kinds of nylon‐6 with different viscosities as matrices. The rheological behaviors of these blends were characterized with capillary rheometry. The morphology was observed with scanning electron microscopy and polarizing optical microscopy. This study showed that although LCP did not fibrillate in binary nylon‐6/LCP blends, LCP fibrillated to a large aspect ratio in some ternary blends after GF was added. The addition of 5 wt % LCP significantly reduced the melt viscosity of nylon‐6/GF blends to such an extent that some nylon‐6/GF/LCP blends had quite low viscosities, not only lower than those of neat resins and nylon‐6/GF blends but also lower than those of corresponding nylon‐6/LCP blends. The mutual influence of the morphology and rheological properties was examined. The great reduction of the melt viscosity was considered the result of LCP fibrillation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1619–1627, 2004
On what terms and why the thermodynamic properties of polymer solutions depend on chain length up to the melt
Authors: Schneider A. , Schuld N. , Bercea M. , Wolf B. A.
Published: March 2004

Theoretical considerations based on chain connectivity and conformational variability of polymers have led to an uncomplicated relation for the dependence of the Flory–Huggins interaction parameter (χ) on the volume fraction of the polymer (ϕ) and on its number of segments (N). The validity of this expression was tested extensively with vapor‐pressure measurements and inverse gas chromatography (complemented by osmotic and light scattering data from the literature) for solutions of poly(dimethylsiloxane) in thermodynamically vastly different solvents such as n‐octane (n‐C8), toluene (TL), and methylethylketone (MEK) over the entire range of composition for at least six different molecular masses of the polymer. The new approach is capable of modeling the measured χ (ϕ, N), regardless of the thermodynamic quality of the solvent, in contrast to traditional expressions, which are often restricted to good solvents but fail for bad mixtures and vice versa. At constant polymer concentration, the χ values were lowest for n‐C8 (best solvent) and highest for MEK (Θ solvent); the data for TL fell between them. The influences of N depended strongly on the thermodynamic quality of the solvent and were not restricted to dilute solutions. For good solvents, χ increased with rising N. The effect was most pronounced for n‐C8, where the different curves for χ (ϕ) fanned out considerably. The influences of N were less distinct for TL, and for MEK they vanished at the (endothermal) θ temperature. For worse than θ conditions, the χ values of the long chains were less than that of the short ones. This change in the sign of N agreed with this concept of conformational relaxation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1601–1609, 2004
Electrochemical, spectroscopic, and thermal studies on interactions of linear poly(acrylic acid) with uranyl ions in aqueous solutions
Authors: Dubolazov Artem V. , Güven Olgun , Pekel Nursel , Azhgozhinova Galiya S. , Mun Grigoriy A. , Nurkeeva Zauresh S.
Published: March 2004

The formation of complexes between linear poly(acrylic acid) (PAA) and uranyl ions in aqueous solutions was studied with conductometry, potentiometry, thermal analysis, Fourier transform infrared, and luminescence spectroscopy methods. The stoichiometry of the PAA/UO complex on repeating units of a PAA basis was determined to be 2:1. IR spectroscopy studies made on solid complexes showed that the carbonyl stretching absorption band of PAA was shifted to a higher wave number, and a new band at 1749 cm−1 in the polycomplex spectrum was observed, confirming the existence of specific interactions between the carboxylate groups of PAA and metal ions. Luminescence spectroscopy studies showed an increase in the intensity of the uranyl‐ion emission spectra and new band formation at 483 nm, further confirming the interaction of UO ions with PAA in aqueous solutions. The thermal behavior of PAA/UO complexes further proved strong interactions in the complex structure. The thermal degradation of the polycomplexes included the main stages of destruction of both PAA and uranyl nitrate. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1610–1618, 2004
The use of sodium carbonate to improve curing treatments against green and blue moulds on citrus fruits
Authors: Plaza Pilar , Usall Josep , Torres Rosario , Abadias Maribel , Smilanick Joseph L , Viñas Immaculada
Published: March 2004

The effectiveness of curing oranges and lemons at 33 °C for 65 h followed by storage under ambient and cold‐storage conditions was investigated. This treatment effectively reduced the incidence of Penicillium digitatum (Pers) Sacc and P italicum Wehmer decay on inoculated and naturally infected oranges and lemons stored at 20 °C for 7 days. However, it failed to control green and blue mould infections on fruits placed in long‐term cold storage, except green mould on oranges, which was effectively controlled. Dipping fruits in a sodium carbonate solution (20 g litre−1) for 2.5 min following a curing treatment at 33 °C for 65 h satisfactorily reduced green and blue mould incidence during subsequent long‐term storage at 4 °C on oranges and at 10 °C on lemons. The efficacy was greater on injured fruits inoculated after the combination of treatments was applied, achieving a 60–80% reduction in decay in comparison with the curing treatment alone in all cases. A significant reduction of blue mould was also observed on fruits inoculated both before the treatments and on those re‐inoculated after the treatments, demonstrating both protectant and eradicant activity. Thus, combining curing at 33 °C for 65 h with sodium carbonate treatment effectively controlled these post‐harvest diseases on artificially inoculated citrus fruits and protected against re‐infection. With naturally inoculated lemons, curing followed by sodium carbonate significantly reduced both green and blue mould incidence, but was not superior to curing alone. With naturally infected oranges, curing significantly reduced blue mould, but decay was not reduced further when followed by sodium carbonate treatment. Copyright © 2004 Society of Chemical Industry
Selection and heritability of resistance to Bacillus thuringiensis subsp kurstaki and transgenic cotton in Helicoverpa armigera (Lepidoptera: Noctuidae)
Authors: Lu Mei‐guang , Rui Chang‐hui , Zhao Jian‐zhou , Jian Gui‐liang , Fan Xian‐lin , Gao Xi‐wu
Published: March 2004

Compared with an unselected susceptible population, a cotton bollworm, Helicoverpa armigera (Hübner), population selected for 22 generations with transgenic cotton leaves (modified Cry1A) in the laboratory developed 11.0‐fold resistance to Cry1Ac (one single‐protein product MVPII). Resistance to Bacillus thuringiensis Berliner subsp kurstaki (Btk) was selected for 22 generations with a 5.2‐fold increase in LC50. The estimated realized heritabilities (h2) of resistance for transgenic‐cotton‐ and Btk‐selected populations were 0.1008 and 0.2341, respectively. This reflects the higher phenotypic variation in response to Cry1Ac in the transgenic‐cotton‐selected population. This variation may have been caused by differences in protein toxin levels expressed in different growth stages of the transgenic cotton. Because of the different slopes of the probit regression lines between Cry1Ac and Btk, the estimated realized h2 cannot be used visually to compare resistance development to Cry1Ac and Btk in H armigera. Thus, the response quotient (Q) of resistance was also estimated. The Q values of resistance for transgenic‐cotton‐ and Btk‐selected populations were 0.0763 and 0.0836, respectively. This showed that the rate of resistance development would be similar in both selection populations. This result indicates that the selection of resistance using transgenic cotton is different from that selected using the single toxin. Resistance risk to transgenic cotton and Btk in field populations was assessed assuming different pressures of selection by using the estimated h2. Assuming the h2 of resistance in a field population was half of the estimated h2, and the population received prolonged and uniform exposure to transgenic cotton or Btk causing >70% mortality in each generation, we predicted that resistance would increase 10‐fold after <23 generations for Cry1Ac in transgenic cotton‐selected‐populations and after <21 generations for Btk in Btk‐selected populations. Cross‐resistance would be expected after <48 generations for Btk in transgenic‐cotton‐selected populations and after <21 generations for Cry1Ac in Btk‐selected population. The results show that the potential to evolve resistance is similar in both transgenic‐cotton‐ and Btk‐selected populations, but that cross‐resistance development to Btk is slower in transgenic‐cotton‐selected populations than cross‐resistance development to Cry1Ac in Btk‐selected populations. Copyright © 2004 Society of Chemical Industry
Cross‐resistance potential of fipronil in Musca domestica
Authors: Kristensen Michael , Jespersen Jørgen B , Knorr Mette
Published: March 2004

The toxicity of fipronil to insecticide‐susceptible houseflies and the cross‐resistance potential of fipronil were determined for six insecticide‐resistant laboratory housefly strains by topical application and feeding bioassay. The insecticide‐resistant strains represented different levels and patterns of resistance to pyrethroids, organophosphates, carbamates and organochlorines. Five strains were almost susceptible to fipronil in feeding bioassay with resistance factors at LC50 between 0.36 and 3.0. Four of these strains were almost susceptible to topically applied fipronil (resistance factors at LD50 were 0.55, 0.83, 3.3 and 2.5, respectively), whereas one strain was 13‐fold resistant to topically applied fipronil. A highly γ‐HCH‐resistant strain, 17e, was 430‐fold resistant to fipronil in topical application bioassay and 23‐fold resistant in feeding bioassay at LD50/LC50. We also tested the toxicity of fipronil in a feeding bioassay and γ‐HCH in topical application bioassay on thirteen housefly field populations. Eleven of the field populations had resistance factors for fipronil ranging from 0.98 to 2.4 at LC50, whereas two populations were 4.0‐ and 4.6‐fold resistant to fipronil. The resistance level to γ‐HCH at LD50 in the field populations ranged from 1.8‐ to 8.1‐fold. The two strains showing fipronil resistance were 3.4‐ and 8.1‐fold resistant to γ‐HCH. Fipronil and γ‐HCH toxicities were positively correlated in the field populations. Biochemical assays of esterase, glutathione S‐transferase and cytochrome P450 monooxygenase indicated that the low fipronil resistance observed in laboratory and field strains could be caused by elevated detoxification or be due to a target‐site resistance mechanism with cross‐resistance to γ‐HCH. Copyright © 2004 Society of Chemical Industry
A second threshold for the hard‐core model on a Bethe lattice
Authors: Brightwell Graham R. , Winkler Peter
Published: March 2004

We determine the approximate value of a critical activity for the hard‐core model on the Bethe lattice, which determines whether the unique simple invariant Gibbs measure is extremal. This “recovery threshold” turns out to be different both from the threshold for unique Gibbs measure and (in contrast to the Ising model) from the threshold for recovery of root information using only statistical information about distant sites. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004
A regression shrinkage method tailored to qualitative regressors and clustered data
Authors: Neumann Anke , Holstein Josiane , Chatellier Gilles , Lepage Eric
Published: March 2004

We propose a shrinkage method for estimation in linear regression models with qualitative regressors. Due to the nature of the shrinkage constraint, this method tends to give estimates that are exactly zero for some groups of coefficients belonging to the same regressor. The method hence results in concise models, since some of the regressors are entirely eliminated. In conjunction with this estimation method, a model with a fixed cluster effect turns out to be closely related to frailty models. We apply the method for modelling hospital readmissions. Copyright © 2004 John Wiley & Sons, Ltd.
A breast cancer prediction model incorporating familial and personal risk factors
Authors: Tyrer Jonathan , Duffy Stephen W. , Cuzick Jack
Published: March 2004

An Erratum has been published for this article in Statistics in Medicine 2005; 24(1):156.

Please note that the corresponding author's e‐mail address has now changed. For further details please click on the link below.

DOI: 10.1002/sim.1913.

Many factors determine a woman's risk of breast cancer. Some of them are genetic and relate to family history, others are based on personal factors such as reproductive history and medical history. While many papers have concentrated on subsets of these risk factors, no papers have incorporated personal risk factors with a detailed genetic analysis. There is a need to combine these factors to provide a better overall determinant of risk. The discovery of the BRCA1 and BRCA2 genes has explained some of the genetic determinants of breast cancer risk, but these genes alone do not explain all of the familial aggregation of breast cancer. We have developed a model incorporating the BRCA genes, a low penetrance gene and personal risk factors. For an individual woman her family history is used in conjuction with Bayes theorem to iteratively produce the likelihood of her carrying any genes predisposing to breast cancer, which in turn affects her likelihood of developing breast cancer. This risk was further refined based on the woman's personal history. The model has been incorporated into a computer program that gives a personalised risk estimate. Copyright © 2004 John Wiley & Sons, Ltd.
Robust Bayesian decision theory applied to optimal dosage
Authors: Abraham Christophe , Daurès Jean‐Pierre
Published: March 2004

We give a model for constructing an utility function u(θ,d) in a dose prescription problem. θ and d denote respectively the patient state of health and the dose. The construction of u is based on the conditional probabilities of several variables. These probabilities are described by logistic models. Obviously, u is only an approximation of the true utility function and that is why we investigate the sensitivity of the final decision with respect to the utility function. We construct a class of utility functions from u and approximate the set of all Bayes actions associated to that class. Then, we measure the sensitivity as the greatest difference between the expected utilities of two Bayes actions. Finally, we apply these results to weighing up a chemotherapy treatment of lung cancer. This application emphasizes the importance of measuring robustness through the utility of decisions rather than the decisions themselves. Copyright© 2004 John Wiley & Sons, Ltd.
A non‐parametric procedure for evaluating treatment effect in the meta‐analysis of survival data
Authors: Moodie Patricia F. , Nelson Norma A. , Koch Gary G.
Published: March 2004

This paper addresses the problem of combining information from independent clinical trials which compare survival distributions of two treatment groups. Current meta‐analytic methods which take censoring into account are often not feasible for meta‐analyses which synthesize summarized results in published (or unpublished) references, as these methods require information usually not reported. The paper presents methodology which uses the log(‐log) survival function difference, (i.e. log(‐logS2(t))‐log(‐logS1(t)), as the contrast index to represent the multiplicative treatment effect on survival in independent trials. This article shows by the second mean value theorem for integrals that this contrast index, denoted as θ, is interpretable as a weighted average on a natural logarithmic scale of hazard ratios within the interval [0,t] in a trial. When the within‐trial proportional hazards assumption is true, θ is the logarithm of the proportionality constant for the common hazard ratio for the interval considered within the trial. In this situation, an important advantage of using θ as a contrast index in the proposed methodology is that the estimation of θ is not affected by length of follow‐up time. Other commonly used indices such as the odds ratio, risk ratio and risk differences do not have this invariance property under the proportional hazard model, since their estimation may be affected by length of follow‐up time as a technical artefact. Thus, the proposed methodology obviates problems which often occur in survival meta‐analysis because trials do not report survival at the same length of follow‐up time. Even when the within‐trial proportional hazards assumption is not realistic, the proposed methodology has the capability of testing a global null hypothesis of no multiplicative treatment effect on the survival distributions of two groups for all studies. A discussion of weighting schemes for meta‐analysis is provided, in particular, a weighting scheme based on effective sample sizes is suggested for the meta‐analysis of time‐to‐event data which involves censoring. A medical example illustrating the methodology is given. A simulation investigation suggested that the methodology performs well in the presence of moderate censoring. Copyright © 2004 John Wiley & Sons, Ltd.
Sensitivity analysis of longitudinal normal data with drop‐outs
Authors: Minini Pascal , Chavance Michel
Published: March 2004

We propose to perform a sensitivity analysis to evaluate the extent to which results from a longitudinal study can be affected by informative drop‐outs. The method is based on a selection model, where the parameter relating the dropout probability to the current observation is not estimated, but fixed to a set of values. This allows to evaluate several hypotheses for the degree of informativeness of the drop‐out process. Expectation and variance of missing data, conditional on the drop‐out time are computed, and a stochastic EM algorithm is used to obtain maximum likelihood estimates. Simulations show that when the drop‐out parameter is correctly specified, unbiased estimates of the other parameters are obtained, and coverage percentages of their confidence intervals are close to their theoretical value. More interestingly, misspecification of the drop‐out parameter does not considerably alter these results. This method was applied to a randomized clinical trial, designed to demonstrate non‐inferiority of an inhaled corticosteroid in terms of bone density, compared with a reference treatment. Sensitivity analysis showed that the conclusion of non‐inferiority was robust against different hypotheses for the drop‐out process. Copyright © 2004 John Wiley & Sons, Ltd.
Outside directors and firm performance during institutional transitions
Authors: Peng Mike W.
Published: March 2004

Do outside directors on corporate boards make a difference in firm performance during institutional transitions? What leads to the practice of appointing outside directors in the absence of legal mandate? This article addresses these two important questions by drawing not only on agency theory, but also resource dependence and institutional theories. Taking advantage of China's institutional transitions, our findings, based on an archival database covering 405 publicly listed firms and 1211 company–years, suggest that outsider directors do make a difference in firm performance, if such performance is measured by sales growth, and that they have little impact on financial performance such as return on equity (ROE). The results also document a bandwagon effect behind the diffusion of the practice of appointing outsiders to corporate boards. The article not only highlights the need to incorporate multiple theories beyond agency theory in corporate governance research, but also generates policy implications in light of the recent trend toward having more outside directors on corporate boards in emerging economies. Copyright © 2004 John Wiley & Sons, Ltd.
Within‐business diversification in technology‐intensive industries
Authors: Stern Ithai , Henderson Andrew D.
Published: March 2004

This study extends diversification research to a new level of analysis, examining how within‐business diversification, which occurs when firms extend existing product lines or expand into new ones, affects organizational survival. While prior research suggests that corporate‐level diversification accounts for relatively little variation in performance, within‐business diversification matters a great deal, by influencing which start‐ups survive and which firms better cope with rapid environmental change. Specifically, we find that the relationship between within‐business diversity and survival is contingent on the amount of environmental change wrought by a firm's competitors as they simultaneously diversify their own product portfolios and innovate technologically. Analysis of the population of U.S. personal computer manufacturers from the industry's founding in 1975 through 1994 supports our premise: Regardless of its effects across businesses, diversification matters a great deal within them. Copyright © 2004 John Wiley & Sons, Ltd.
Influence of Conditions of Maize Starch Enzymatic Hydrolysis on Physicochemical Properties of Glucose Syrups
Authors: Nebesny Ewa , Rosicka Justyna , Tkaczyk Mariola
Published: March 2004

Amylose complexed with lipid is more resistant to the attack of amylolytic enzymes than the free polysaccharide. The susceptibility of amylose‐lipid complexes (AML) present in maize starch to enzymatic digestion still remains obscure, although the enzymatic hydrolysis of AML with defined composition, prepared from amylose and selected lipids, was an objective of several research projects. Therefore our studies were aimed at elucidation of AML properties and their relationship with features of maize starch hydrolysates, particularly with respect to the character of a lipolytic enzyme, additionally used for saccharification, apart from the glucoamylase. Differential scanning calorimetry (DSC) measurements revealed that treatment of maize starch with suitable α‐amylase preparation resulted in significant degradation of AML. More pronounced cleavage of AML can be also achieved by using both amylolytic and lipolytic enzymes for starch saccharification. The lysophospholipase appeared to be particularly active towards AML when used with glucoamylase. The common application of these enzymes brought about an enhanced glucose yield and filtration rate, and better color and transparency of the final product.
Exploratory Studies on the Carboxymethylation of Cassava Starch in Water‐miscible Organic Media
Authors: Jie Yao , Wen‐ren Chen , Manurung Robbert M. , Ganzeveld Klaassien J. , Heeres Hero J.
Published: March 2004

The carboxymethylation of cassava starch using sodium monochloroacetate (SMCA) as an etherification agent was investigated. Mixtures of water and water‐miscible organic liquids were selected as carboxymethylation reaction medium to obtain a high degree of substitution (DS) without changing the granular form and to prevent gelatinization. Factors that affect the process of chemical modification of cassava starch, including the type of solvents, the mass percentage of water in the reaction medium, the mass percentage of starch, the molar ratio of NaOH to SMCA, the theoretical DS (DSt), and the temperature were investigated experimentally. Isopropanol and tert‐butanol appear to be the best solvents for the carboxymethylation process of cassava starch, and the optimum condition for this etherification reaction are a reaction medium consisting of about 10 wt% water, a reaction temperature between 50 and 55°C and a starch mass percentage between 4–8 wt%. When applying these conditions in combination with a DSt of 2.5, granular modified cassava starch with a DS of 1.4 can be obtained. The experimental results will be compared with those reported for other types of granular starches.
The Role of Hydrogen Bonding in Amylose Gelation
Authors: McGrane Scott J. , Mainwaring David E. , Cornell Hugh J. , Rix Colin J.
Published: March 2004

Studies of the rheological properties of amylose gels in mixtures of water and DMSO have shown that these properties are dependent upon the formation of intramolecular and intermolecular hydrogen bonds. In DMSO, it is proposed that amylose has a tight helical conformation which is maintained by intramolecular hydrogen bonding. When water is added it is proposed that intramolecular hydrogen bonds are replaced with intermolecular hydrogen bonds and thus the rheological properties are changed due to the more extended and flexible amylose molecules adopting an interrupted helical conformation.

Because of these changes in conformation, increased water content results in strong elastic gels, commensurate with it being the dominant gel‐forming component in starch, due to its ability to form networks with water through intermolecular hydrogen bonding. The addition of various polyols to solutions of amylose in DMSO also resulted in strong elastic gels being formed. It is proposed that polyols such as 1,3‐propanediol are also able to form networks in a similar way to water.

The use of intermolecular hydrogen bond breaking agents, such as urea, reduced gel strength significantly, but the intra‐molecular bond‐breaking agent, 1,1,3,3‐tetramethyl urea (TMU), was not so effective. The results of this work are further evidence of intermolecular hydrogen bonding networks between amylose and water as being of fundamental importance in the strength of starch gels.