bluuebunny/crossref_metadata_2025 huggingface dataset:
The Structural, Molecular and Functional Properties of Lignin‐Containing Beechwood Glucuronoxylan
Authors: Hromádková Zdenka , Ebringerová Anna , Malovíková Anna
Published: February 2006

The samples of 4‐O‐methyl‐D‐glucurono‐D‐xylan (GX) with different lignin and uronic acid (MeUA) contents were prepared from beechwood by various procedures. The re‐dissolution process of the partially water‐soluble GX‐2 lyophilizate in aqueous medium depended on the content and distribution of MeUA. In contrast to the supernatant after ultracentrifugation, the sediment had a significantly lower MeUA content and showed mainly high‐molecular mass components. A part of lignin degradation products is separable by repeated dissolution and precipitation of GX in acidic and alkaline 80% ethanolic media with assistance of ultrasound. Irradiation in acidic ethanol (GX‐3/ac) showed no effect on the distribution of the UV254‐absorbing component. GX‐3 sonicated in neutral and alkaline media (GX‐3/ne, GX‐3/alk) lost water solubility. The lignin‐rich GX samples showed remarkable emulsifying efficiency and protein foam stabilization effect. In addition, the presence of phenolics provided antioxidant properties to these xylan preparations indicating their potential as polymeric radical scavengers.
Cationic Xylan Derivatives with High Degree of Functionalization
Authors: Schwikal Katrin , Heinze Thomas , Ebringerová Anna , Petzold Katrin
Published: February 2006

Xylan from birch wood was characterized regarding both the supramolecular structure (X‐ray, CP/MAS 13C‐NMR) and the sugar composition. The reaction of the birch wood xylan with 2,3‐epoxypropyltrimethylammonium chloride in 1,2‐dimethoxyethane as slurry medium yields water‐soluble, cationic 2‐hydroxypropyltrimethylammonium xylan derivatives with high degree of substitution (DS). The DS values up to 1.6 can be controlled by adjusting the molar ratio in a one step synthesis. The structure of the cationic xylan derivatives was confirmed by means of DEPT(135) NMR spectroscopy. Film forming properties of cationic xylan derivatives were investigated with SEM measurements.
Synthesis of the Cellulose Model Compound Methyl 4″‐O‐Methyl‐β‐D‐Cellotrioside
Authors: del Carmen Ruiz Ruiz Maria , Querner Jens , Adorjan Immanuel , Kosma Paul , Rosenau Thomas
Published: February 2006

A high‐yield synthetic route towards methyl 4″‐O‐methyl‐β‐D‐cellotrioside (17) via cellobioside acceptor 8 and glucosyl fluoride donor 15 was established. The former was synthesized from cellobiose peracetate in 7 steps and 21% overall yield, while the latter was obtained from methyl β‐D‐glucopyranoside in a 6‐step‐synthesis with 19% yield. Glycosidation afforded 13% of α‐compound besides the desired β‐isomer (31%). The target compound, being the higher homologue of the recently prepared 4′‐O‐methyl‐β‐D‐cellobioside (1), is required to study by solid‐state techniques the hydrogen bond network in cellodextrins and cellulose, and its changes upon swelling and dissolution.
Comparison of Aqueous and Non‐Aqueous Treatments of Cellulose to Reduce Copper‐Catalyzed Oxidation Processes
Authors: Henniges Ute , Banik Gerhard , Potthast Antje
Published: February 2006

Summary. The present paper examines oxidative degradation of cellulose catalyzed by presence of Cu1+and Cu2+ ions in the context of historic paper conservation treatments. Aqueous treatments of degraded papers further spread transition metal ions, such as copper, across the fibre matrix, and therefore augment the detrimental effect of these ions. In the paper industry, the inhibiting effects of magnesium ions on metal‐catalyzed degradation of cellulose contaminated with metal impurities have been observed. Also, magnesium compounds dissolved in alcoholic or aqueous solutions are generally used in paper conservation as deacidification agents. Paper samples with artificially produced copper corrosion served as mock‐ups for examination and comparison of different treatments which focused on the inhibiting effect of magnesium and antioxidants. Analytical examination of molecular weight distribution, carbonyl content, carboxyl content, and surface pH was performed. Results show an inhibiting effect of magnesium on copper‐catalyzed cellulose degradation, although less pronounced than expected.
Comparing Dichromate Oxidation and Size Exclusion Chromatography of Dissolved Carbohydrates
Authors: Schmidt Ingeborg , Fischer Klaus , Weightman Derek
Published: February 2006

Standardised methods are used to characterise the pulp or cellulosic material for its alkali resistance and alkali solubility. Today, pulp is usually characterised by its solubility in sodium hydroxide. The characterisation test was based on the treatment of pulp with sodium hydroxide solution of a defined concentration, according to a specified procedure. The dissolved organic matter was then determined by dichromate oxidation. The results obtained by size exclusion chromatography showed that both the amount and the molecular weight of the dissolved carbohydrates vary when investigating solubility and α‐cellulose content of pulps. The results show further that S18 values obtained by dichromate oxidation are overestimated when characterising pulps containing higher amounts of hemicellulose and/ or short chain cellulose, compared with results obtained by the SEC method. On the contrary, S10 values are overestimated when determined by dichromate oxidation in higher alpha pulps.
Expression of heregulin by mouse mammary tumor cells: Role in activation of ErbB receptors
Authors: Schmitt M. , Walker M.P. , Richards R.G. , Bocchinfuso W.P. , Fukuda T. , Medina D. , Kittrell F.S. , Korach K.S. , DiAugustine R.P.
Published: February 2006

The inappropriate activation of one or more members of the ErbB family of receptor tyrosine kinases [ErbB‐1 (EGFR), ErbB‐2, ErbB‐3, ErbB‐4] has been linked with oncogenesis. ErbB‐2 is frequently coexpressed with ErbB‐3 in breast cancer cells and in the presence of the ligand heregulin (HRG) the ErbB‐2/ErbB‐3 receptors form a signaling heterodimer that can affect cell proliferation and apoptosis. The major goal of the present study was to determine whether endogenous HRG causes autocrine/paracrine activation of ErbB‐2/ErbB‐3 and contributes to the proliferation of mammary epithelial tumor cells. Tyrosine‐phosphorylated (activated) ErbB‐2 and ErbB‐3 receptors were detected in the majority of extracts from tumors that had formed spontaneously or as a result of oncogene expression. HRG‐1 transcripts and protein were found in the epithelial cells of most of these mouse mammary tumors. Various mouse mammary cell lines also contained activated ErbB‐2/ErbB‐3 and HRG transcripts. A ∼50 kDa C‐terminal fragment of pro‐HRG was detected, which indicates that the HRG‐1 precursor is readily processed by these cells. It is likely that the secreted mature HRG activated the ErbB‐2/3 receptors. Addition of an antiserum against HRG to the mammary epithelial tumor cell line TM‐6 reduced ErbB‐3 Tyr‐phosphorylation. Treatment with HRG‐1 siRNA oligonucleotides or infection with a retroviral construct to stably express HRG siRNA effectively reduced HRG protein levels, ErbB‐2/ErbB‐3 activation, and the rate of proliferation, which could be reversed by the addition of HRG. The cumulative findings from these experiments show that coexpression of the HRG ligand contributes to activation of ErbB‐2/Erb‐3 in mouse mammary tumor cells in an autocrine or paracrine fashion. Published 2006 Wiley‐Liss, Inc.
Genetic and epigenetic alterations in lung tumors from bitransgenic Ki‐rasG12C expressing mice
Authors: Floyd Heather S. , Jennings‐Gee Jamie E. , Kock Nancy D. , Miller Mark Steven
Published: February 2006

Mutations in Ki‐ras occur in approximately 30–50% of patients with adenocarcinoma (AC) of the lung. We previously reported the development of a bitransgenic mouse model that expressed the human Ki‐rasG12C allele in a lung‐specific, tetracycline‐inducible manner and gave rise to benign lung tumors. In the current study, these benign tumors, which represent relatively early lesions in neoplastic progression, were analyzed for molecular alterations secondary to mutant Ki‐ras expression to determine the gene(s) that contribute to adenoma (AD) development. Tumors were removed following doxycycline (DOX) treatment for 9 and 12 mo and examined for alterations in cell‐cycle regulatory genes. Quantification of mRNA expression for cyclin D1, retinoblastoma, p16Ink4a, p19Arf, and survivin was carried out by real‐time PCR. All of the tumors examined exhibited a mean reduction of approximately fivefold for the retinoblastoma gene (P < 0.02). Increased expression of both p19Arf and survivin were detected in a majority of the tumors examined (P < 0.01 and 0.001, respectively), but no change in cyclin D1 RNA expression was observed. A subset of the lung tumors (8/28) displayed reduced levels of p16Ink4a expression (P = 0.02). Immunohistochemical analysis confirmed the upregulation of p19Arf and survivin in all 10 of the lung tumors examined. However, increased staining for cyclin D1 was observed in the tumor tissue. In addition, increased levels of activated p53 were found in lung tumor tissues stained with an anti‐phospho‐p53 antibody, while an absence of staining was observed with an anti‐phospho‐pRb antibody in both normal control and tumor tissue. Analysis of the methylation status of p16Ink4a by methylation‐specific PCR (MSP) demonstrated that seven of eight tumors exhibiting decreased expression of p16Ink4a had at least partial methylation of the promoter region. Single stranded conformational polymorphism (SSCP) analysis demonstrated that neither exons 1 or 2 of p16Ink4a nor exons 5–8 of p53 exhibited mutations. These data thus identify alterations in specific genes and pathways that combine with the mutation in Ki‐ras to promote the formation of benign lung tumors and suggest potential targets for the development of novel chemotherapeutic and chemopreventive agents during the early stages of lung tumor progression. © 2006 Wiley‐Liss, Inc.
Differential susceptibility to chemically induced thymic lymphomas in SENCARB and SSIN inbred mice
Authors: Benavides Fernando , Gomez Gregorio , Venables‐Griffith Ann , Lambertz Isabel , Flores Mónica , Angel Joe M. , Fuchs‐Young Robin , Richie Ellen R. , Conti Claudio J.
Published: February 2006

In the past 20 yr, several inbred strains have been derived from SENCAR outbred mice. These strains display different susceptibility to the induction of papillomas and progression to squamous cell carcinomas (SCC) in the skin after chemical carcinogenesis. In the present study, we showed that one of these strains SENCARB/Pt was highly susceptible to the development of N‐methyl‐N‐nitrosourea (MNU)‐ and 7,12‐dimethylbenz[a]anthracene (DMBA)‐induced lymphomas. In contrast, the SSIN/Sprd inbred strain is completely resistant to T‐cell lymphomagenesis by both carcinogens. Within 175 d after a single injection of 75 mg/kilogram body weight (kbw) of MNU, SENCARB/Pt mice exhibited a 91.6% incidence of lymphoma. In addition, during an independent tumorigenesis study with repeated doses of intragastric DMBA, SENCARB/Pt mice showed an incidence of 75% lymphoma development 300 d after the last treatment. Histopathological and flow cytometric parameters indicated that the lymphomas were of the T‐cell lineage. In order to study the genetics of MNU‐induced tumorigenesis, we generated F1 hybrid mice between SSIN/Sprd and SENCARB/Pt mice. Tumor incidence in MNU‐injected F1 mice suggested that the high tumor incidence is a dominant trait. Loss of heterozygosity (LOH) analysis in these tumor samples revealed allelic imbalances on chromosomes 15 and 19. Given that these inbred strains are closely related, it is likely that a relatively small number of loci are responsible for the observed differences in susceptibility. Therefore, these SENCAR inbred strains constitute important new tools to study the genetic basis of resistance and susceptibility to chemically induced thymic lymphoma formation. © 2006 Wiley‐Liss, Inc.
Changes in cortical inhibition during task‐specific contractions in primary writing tremor patients
Authors: Ljubisavljevic Milos , Kacar Aleksandra , Milanovic Sladjan , Svetel Marina , Kostic Vladimir S.
Published: February 2006

Primary writing tremor (PWT) is a rare disease of unknown pathophysiology. We studied changes in silent period (SP) duration, after transcranial magnetic stimulation (TMS), set at 20% above the motor threshold in 6 PWT patients and 7 healthy control subjects. SP duration was tested during a task‐specific act, i.e., writing that induced tremor in all patients in the affected hand (Wr); nonspecific voluntary contraction of intensity, matching that developed during writing (VCWr); and during near maximal voluntary contraction (VCNmax). There were no differences in SP duration during Wr and VCWr contraction on the right affected side or between sides in both PWT patients and control subjects, nor between the groups. However, during VCNmax, SP significantly shortened on both sides in PWT patients, whereas there were no changes in control subjects. Although it appears that inhibitory mechanism are not directly involved in the generation of the tremulous activity, the shortening of SP indicates that central inhibitory mechanisms are affected in PWT patients. Therefore, whereas the underlying pathophysiological mechanisms in PWT and writer's cramp may share common features, the results indicate that PWT is not a variant of focal task‐specific dystonia but rather a separate nosological entity. © 2006 Movement Disorder Society
PINK1 mutations in sporadic early‐onset Parkinson's disease
Authors: Tan Eng‐King , Yew Kenneth , Chua Eva , Puvan K. , Shen Hui , Lee Esther , Puong Kim‐Yoong , Zhao Yi , Pavanni Ratnagopal , Wong Meng‐Cheong , Jamora Dominic , de Silva Deidre , Moe Kyaw‐Thu , Woon Fung‐Peng , Yuen Yih , Tan Louis
Published: February 2006

Pathogenic PINK1 mutations have been described in PARK6‐linked Parkinson's disease (PD) patients of Asian origin. However, data on the frequency of PINK1 mutations in sporadic early‐onset Parkinson's disease (EOPD) Asian patients are lacking. The objectives of this study were to report the frequency of PINK1 mutations of sporadic EOPD in an Asian cohort comprising of ethnic Chinese, Malays, and Indians, and to highlight a PINK1‐positive patient who presented with restless legs symptoms. Eighty consecutive sporadic EOPD patients from the movement disorder clinics of two major tertiary institutions in the country were included. We performed sequence analysis of all the coding and exon–intron junctions of the PINK1 using specific primer sets. In addition, we genotyped polymorphisms detected from the analysis in a group of sporadic PD patients and controls. Three different mutations (two homozygous nonsense and one heterozygous missense) in the putative kinase domain were found in three patients, giving a 3.7% frequency of PINK1 mutations in our EOPD cohort. All the mutations were absent in 200 healthy controls. One patient with a novel homozygous nonsense PINK1 mutation presented unusually with restless legs symptoms. Separately, analysis of the frequency of four PINK1 polymorphisms in a group of sporadic PD and controls did not reveal any significant differences. We highlight a 3.7% frequency of PINK1 mutations in an Asian cohort (ethnic Chinese, Malay, and Indian) of EOPD. The phenotypic spectrum associated with PINK1‐positive patients may be wider than previously reported. Polymorphisms of PINK1 do not appear to modulate risk of PD in our population. © 2006 Movement Disorder Society
Asymptotic behaviour of solutions of quasilinear evolutionary partial differential equations of parabolic type on unbounded spatial intervals
Authors: Poul Lukáš
Published: February 2006

We study the long‐time behaviour of solutions to a quasilinear parabolic problem on a half‐line. The main result lies in showing the existence of a positive solution that converges to the travelling wave of solution to the stationary problem on the whole line. The main tools used here are the zero number theory and the concentration compactness principle. This result is a generalization of a result know for semilinear parabolic equations. Copyright © 2006 John Wiley & Sons, Ltd.
Modifying CLJP to select grid hierarchies with lower operator complexities and better performance
Authors: Alber David M.
Published: February 2006

Algebraic multigrid (AMG) is an efficient algorithm for solving certain types of large, sparse linear systems. For solving very large problems with AMG it becomes necessary to use parallel algorithms. Coarse grid selection algorithms such as CLJP were created to parallelize the setup phase of AMG. For some problems, such as those discretized on structured meshes, CLJP tends to select coarse grids with more nodes than alternative coarsening algorithms. In this paper, the cause for the selection of too many coarse nodes by CLJP is examined, and a new technique which lowers the operator complexities generated by CLJP is introduced. To validate the new method, the modified CLJP is compared to other coarsening algorithms for large‐scale problems. Copyright © 2006 John Wiley & Sons, Ltd.
A state‐dependent Riccati equation‐based estimator approach for HIV feedback control
Authors: Banks H. T. , Kwon Hee‐Dae , Toivanen J. A. , Tran H. T.
Published: February 2006

We consider optimal dynamic multidrug therapies for human immunodeficiency virus (HIV) type 1 infection. In this context, we describe an optimal tracking problem attempting to drive the states of the system to a stationary state in which the viral load is low and the immune response is strong. We consider optimal feedback control with full‐state as well as with partial‐state measurements. In the case of partial‐state measurement, a state estimator is constructed based on viral load and T‐cell count measurements. We demonstrate by numerical simulations that by anticipation of and response to the disease progression, the dynamic multidrug strategy reduces the viral load, increases the CD4+ T‐cell count and improves the immune response. Copyright © 2006 John Wiley & Sons, Ltd.
On–off minimum‐time control with limited fuel usage: near global optima via linear programming
Authors: Driessen Brian J.
Published: February 2006

A method for finding a global optimum to the on–off minimum‐time control problem with limited fuel usage is presented. Each control can take on only three possible values: maximum, zero, or minimum. The simplex method for linear systems naturally yields nearly such a solution for the re‐formulation presented herein because the simplex method always produces an extreme point solution to the linear program. Numerical examples for the benchmark linear flexible system are presented. Copyright © 2006 John Wiley & Sons, Ltd.
Practical syntheses of [1,3,5]‐triazine dendritic molecules on solid supports
Authors: Dilly Suzanne J. , Carlisle Steven J. , Clark Andrew J. , Shepherd Andrew R. , Smith Stephen C. , Taylor Paul C. , Marsh Andrew
Published: February 2006

A practical and divergent synthesis of supported [1,3,5]‐triazine dendritic molecules on Wang resin, PEGA resin, SynPhase™ Lanterns, and silica gel is described. The alkylamine linkers used allow derivatization with functionality for both synthetic (e.g., supported reagent and scavenger activity) and chemical biology applications. The use of supported intermediates allows differentiation of symmetric linkers without the need for protecting group chemistry. The synthetic route uses inexpensive, readily available starting materials in a straightforward and scaleable strategy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2248–2259, 2006
Synthesis and properties of Q‐silicon crosslinked siloxane networks: H3PO4‐catalyzed sol–gel dehydration/crosslinking of α,ω‐bis(hydroxy)oligodimethylsiloxanes with tetrakis(hydroxydimethylsiloxy)silane
Authors: Gädda Thomas M. , Kus Esra , Mansfeld Florian , Finlay John A. , Callow James A. , Callow Maureen E. , Kowalke Gregory L. , Wendt Dean E. , Weber William P.
Published: February 2006

Six silicate‐crosslinked oligodimethylsiloxane thin films were prepared by the phosphoric acid (1 mol %) catalyzed condensation of α,ω‐bis(hydroxy)oligodimethylsiloxane (P) and tetrakis(hydroxydimethylsiloxy)silane (Q). Other acid catalysts were evaluated. P and Q were prepared by the Pd‐catalyzed oxidation of the corresponding SiH compounds with water. The starting materials were characterized by IR and 1H, 13C, and 29Si NMR. A thermal cure was achieved with H3PO4 in 24 h and with poly(phosphoric acid) in 3 h at 110–120 °C. Dynamic mechanical analysis was used to determine the glass‐transition temperatures and to evaluate the mechanical properties of the films. Their thermal stabilities (≥300 °C) in air and N2 were determined by thermogravimetric analysis. Small amounts of non‐crosslinked P were recovered from the films by Soxhlet extractions with CH2Cl2 and analyzed by IR, gel permeation chromatography, and 29Si NMR. The crosslink densities were evaluated by the CH2Cl2 absorption capacities of the films. The surface properties of the films were determined by static and dynamic contact‐angle measurements. Electrochemical impedance spectroscopy was carried out to evaluate the corrosion‐protective properties of the coatings on mild steel as a function of the exposure time to 0.5 N NaCl. The biofoul‐release properties of the films were evaluated with sporelings from mature Ulva linza plants and barnacles. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2237–2247, 2006
Phase morphology development in PP/PA6 blends induced by a maleated thermoplastic elastomer
Authors: Liu Hongzhi , Xie Tingxiu , Zhang Ying , Ou Yuchun , Yang Guisheng
Published: February 2006

The effects of maleated thermoplastic elastomer (TPEg) on morphological development of polypropylene (PP)/polyamide 6 (PA6) blends with a fixed PA6 content (30 wt %) were investigated. For purpose of comparison, nonmaleated thermoplastic elastomer (TPE) was also added to the above binary blends. A comparative study of FTIR spectroscopy in above both ternary blends confirmed the formation of in situ graft copolymer in the PP/PA6/TPEg blend. Dynamic mechanical analysis (DMA) indicated that un‐like TPE, the incorporation of TPEg remarkably affected both intensity and position of loss peaks of blend components. Scanning electron microscopy (SEM) demonstrated that PP/PA6/TPE blends still exhibited poor interfacial adhesion between the dispersed phase and matrix. However, the use of TPEg induced a finer dispersion and promoted interfacial adhesion. Transmission electron microscopy (TEM) for PP/PA6/TPEg blends showed that a core‐shell structure consisting of PA6 particles encapsulated by an interlayer was formed in PP matrix. With the concentration of TPEg increasing, the dispersed core‐shell particles morphology was found to transform from discrete acorn‐type particles to agglomerate with increasing degree of encapsulation. The modified Harkin's equation was applied to illustrate the evolution of morphology with TPEg concentration. “Droplet‐sandwiched experiments” further confirmed the encapsulation morphology in PP/PA6/TPEg blends. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1050–1061, 2006
Luminescent properties of Ce3+ ions in Ca2B5O9Cl
Authors: Dotsenko V. P. , Berezovskaya I. V. , Efryushina N. P. , Shabanov E. V. , Voloshinovskii A. S.
Published: February 2006

The luminescent properties of Ce3+ ions in Ca2B5O9Cl have been studied upon excitation in the 3.5–25 eV region. The energies of all 5d crystal field levels of Ce3+ ions in double doped Ca2B5O9Cl:Ce3+, Na+ have been determined. In addition to the 4f → 5d excitation bands, the excitation spectrum of the Ce3+ emission shows a band with a maximum at 7.7 eV, which is attributed to the absorption of the borate groups. The influence of the structural features of Ca2B5O9Cl on the luminescent behavior of Ce3+ is discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of dc conductance of two‐dimensional heterogeneous system: application to carbon wires made by ion irradiation on polycrystalline diamond
Authors: Poklonski N. A. , Kocherzhenko A. A. , Benediktovitch A. I. , Mitsianok V. V. , Zaitsev A. M.
Published: February 2006

A percolation model of two‐dimensional heterogeneous system composed of two conductive phases and a method for calculating the macroscopic electric conductance of such a system in direct current regime is proposed. The parameters of the model are its geometrical dimensions, the conductance of the two phases and the relative fractions of the phases in the system. The model satisfactorily describes the non‐linear dependence on width of conductance of the carbon nano‐ and microwires made on polycrystalline diamond surface by focused ion beam irradiation. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mean potential of Bethe in the classical problem of calculating bulk electrostatic potentials in crystals
Authors: Kholopov Eugene V.
Published: February 2006

The mean potential of Bethe is discussed as a correction modifying direct potential series to translation‐invariant potentials in the bulk. As shown, this effect is associated with special periodic boundary conditions imposed at infinity. As a result, a unique potential solution independent of any particular choice of the unit cell arises. Based on this finding, the classical problem of asymmetry of Evjen's potentials and the problem of definition of the bulk Coulomb energy are readily resolved. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim )
Special directions for surface integrals in cubic lattices with application to the evaluation of the COMPTON profile of copper
Authors: Bross H.
Published: February 2006

Several sets of special directions are presented which allow the integration of functions with full cubic symmetry over a solid angle. These sets yield a higher accuracy than those published up to now. The sets corresponding to N = 2, 3, 4, 6 and 7 directions satisfy the criteria of the best choice rather well. But even for N = 8, 10, 12, 24 and 48 the sets proposed allow an approximation by a finite series of cubic harmonics with high precision.

These sets are useful both for experimentalists and theoreticians. Extensive measurements e.g. experiments needing large exposure time are suitably done with a small set whereas theoreticians will prefer the big sets due the large CPU capacities now available. The power of these considerations is illustrated by evaluation of the spherical average of the Compton profile of Cu. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Compton scattering study of ZnSe
Authors: Vyas V. , Purvia V. , Sharma Y. C. , Joshi K. B. , Sharma B. K.
Published: February 2006

In this work we report on the Compton scattering study of ZnSe. The Am241 Compton spectrometer, which uses 59.54 keV gamma rays, has been used for the measurements. The data has been compared with the ionic model based calculations for various Zn+x Se–x configurations (x varying from 0 to 2) and also with the Compton profiles computed from the local and non‐local empirical pseudopotential methods. Although, the agreement is better with the local empirical pseudopotential calculation compared to the non‐local method, the best agreement has been found with the ionic model for Zn+2Se–2 configuration suggesting that the bonding in this compound is mainly ionic in nature. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The European Conference Physics of Magnetism (PM'05) Poznań, Poland, 24–27 June 2005
Authors: Idzikowski B. , Barnaś J. , Micnas R. , Jezierski A. , Szajek A. , Wojciechowski R. J.
Published: February 2006

Papers presented at The European Conference Physics of Magnetism (PM'05) were published in the January 2006 issues of physica status solidi (b) and (c) [1, 2]. Please find the Preface by the Guest Editors of the Proceedings as well as the listings of Conference Chairs, Committees and Sponsors, which were unintentionally omitted from the journals, reprinted here.
Geometric Representation of Association between Categories
Authors: Heiser Willem J.
Published: February 2006

Categories can be counted, rated, or ranked, but they cannot be measured. Likewise, persons or individuals can be counted, rated, or ranked, but they cannot be measured either. Nevertheless, psychology has realized early on that it can take an indirect road to measurement: What can be measured is the strength of association between categories in samples or populations, and what can be quantitatively compared are counts, ratings, or rankings made under different circumstances, or originating from different persons. The strong demand for quantitative analysis of categorical data has thus created a variety of statistical methods, with substantial contributions from psychometrics and sociometrics. What is the common basis of these methods dealing with categories? The basic element they share is that the sample space has a special geometry, in which categories (or persons) are point masses forming a simplex, while distributions of counts or profiles of ratings are centers of gravity, which are also point masses. Rankings form a discrete subset in the interior of the simplex, known as the permutation polytope, and paired comparisons form another subset on the edges of the simplex. Distances between point masses form the basic tool of analysis. The paper gives some history of major concepts, which naturally leads to a new concept: the shadow point. It is then shown how loglinear models, Luce and Rasch models, unfolding models, correspondence analysis and homogeneity analysis, forced classification and classification trees, as well as other models and methods, fit into this particular geometrical framework.
Local Influence Analysis of Nonlinear Structural Equation Models
Authors: Lee Sik-Yum , Tang Nian-Sheng
Published: February 2006

By regarding the latent random vectors as hypothetical missing data and based on the conditional expectation of the complete-data log-likelihood function in the EM algorithm, we investigate assessment of local influence of various perturbation schemes in a nonlinear structural equation model. The basic building blocks of local influence analysis are computed via observations of the latent variables generated by the Metropolis-Hastings algorithm, while the diagnostic measures are obtained via the conformal normal curvature. Seven perturbation schemes, including some perturbation schemes on latent vectors, are investigated. The proposed procedure is illustrated by a simulation study and a real example.
Selection of Variables in Exploratory Factor Analysis: An Empirical Comparison of a Stepwise and Traditional Approach
Authors: Hogarty Kristine Y. , Kromrey Jeffrey D. , Ferron John M. , Hines Constance V.
Published: February 2006

The purpose of this study was to investigate and compare the performance of a stepwise variable selection algorithm to traditional exploratory factor analysis. The Monte Carlo study included six factors in the design; the number of common factors; the number of variables explained by the common factors; the magnitude of factor loadings; the number of variables not explained by the common factors; the type of anomaly evidenced by the poorly explained variables; and sample size. The performance of the methods was evaluated in terms of selection and pattern accuracy, and bias and root mean squared error of the structure coefficients. Results indicate that the stepwise algorithm was generally ineffective at excluding anomalous variables from the factor model. The poor selection accuracy of the stepwise approach suggests that it should be avoided.
The Order-Restricted Association Model: Two Estimation Algorithms and Issues in Testing
Authors: Galindo-Garre Francisca , Vermunt Jeroen K.
Published: February 2006

This paper presents a row-column (RC) association model in which the estimated row and column scores are forced to be in agreement with an a priori specified ordering. Two efficient algorithms for finding the order-restricted maximum likelihood (ML) estimates are proposed and their reliability under different degrees of association is investigated by a simulation study. We propose testing order-restricted RC models using a parametric bootstrap procedure, which turns out to yield reliable p values, except for situations in which the association between the two variables is very weak. The use of order-restricted RC models is illustrated by means of an empirical example.
Some Further Inequalities and an Identity in Factor Analysis
Authors: Darroch John N.
Published: February 2006

Let x denote one of the variables in a factor analysis model. In 1935 Roff proved that the communality of x is greater than or equal to the squared multiple correlation coefficient of x with the other variables in the model. In this paper it is shown that the inequality is the first of an infinite sequence of inequalities, each sharper than the one before, and that the condition for equality is the same for all members of the sequence. Also, the limiting inequality is considered and the condition for equality derived. As this condition is always satisfied in a factor analysis model, the inequality is really an identity.
Note on the Relation between Kendall’s Tau and the Cronholm-Revusky Test
Authors: Bennett B. M.
Published: February 2006

It is shown that the rank test R proposed by Cronholm and Revusky for comparing the effect of two treatments on a single group of n subjects is a linear function of Kendall’s τ-coefficient. The asymptotic results of Bennett for the distribution of R are also applicable to that of τ under a class of nonnull hypotheses.
The Estimation of Ultrametric and Path Length Trees from Rectangular Proximity Data
Authors: De Soete Geert , DeSarbo Wayne S. , Furnas George W. , Carroll J. Douglas
Published: February 2006

A least-squares algorithm for fitting ultrametric and path length or additive trees to two-way, two-mode proximity data is presented. The algorithm utilizes a penalty function to enforce the ultrametric inequality generalized for asymmetric, and generally rectangular (rather than square) proximity matrices in estimating an ultrametric tree. This stage is used in an alternating least-squares fashion with closed-form formulas for estimating path length constants for deriving path length trees. The algorithm is evaluated via two Monte Carlo studies. Examples of fitting ultrametric and path length trees are presented.
A Loss Function for Alpha Factor Analysis
Authors: Derflinger Gerhard
Published: February 2006

Most of the factor solutions can be got by minimizing a corresponding loss function. However, up to now, a loss function for the alpha factor analysis (AFA) has not been known. The present paper establishes such a loss function for the AFA. Some analogies to the maximum likelihood factor analysis are discussed.
Testing the Conditional Independence and Monotonicity Assumptions of Item Response Theory
Authors: Rosenbaum Paul R.
Published: February 2006

When item characteristic curves are nondecreasing functions of a latent variable, the conditional or local independence of item responses given the latent variable implies nonnegative conditional covariances between all monotone increasing functions of a set of item responses given any function of the remaining item responses. This general result provides a basis for testing the conditional independence assumption without first specifying a parametric form for the nondecreasing item characteristic curves. The proposed tests are simple, have known asymptotic null distributions, and possess certain optimal properties. In an example, the conditional independence hypothesis is rejected for all possible forms of monotone item characteristic curves.
The Asymptotic Distribution of Response Probabilities in the Audley-Jonckheere Learning Model
Authors: Wolter David G. , Earl Robert W.
Published: February 2006

The asymptotic distributions of response probabilities in the Audley-Jonckheere learning model, as applied to the two-choice learning situation, are described for (1) the experimenter-controlled events model, (2) the subject-controlled events model, and (3) the experimenter-subject-controlled events model.
Note on the “Longitudinal Factor Analysis” Model
Authors: Nesselroade John R.
Published: February 2006

The “longitudinal factor analysis” model, which uniquely resolves factors from two occasions of data representing the same persons measured on the same test battery, is shown to be derivable by application of canonical correlation procedures to factor scores. Interpreted in this light, it is suggested that, in attaining its objective, “longitudinal factor analysis” maximizes temporal stability of factor scores—an emphasis which may be warranted for some types of change but not for others.
Factor Analysis by Generalized Least Squares
Authors: Jöreskog Karl G. , Goldberger Arthur S.
Published: February 2006

Aitken’s generalized least squares (GLS) principle, with the inverse of the observed variance-covariance matrix as a weight matrix, is applied to estimate the factor analysis model in the exploratory (unrestricted) case. It is shown that the GLS estimates are scale free and asymptotically efficient. The estimates are computed by a rapidly converging Newton-Raphson procedure. A new technique is used to deal with Heywood cases effectively.
An Individual Difference Model for the Multidimensional Analysis of Preference Data
Authors: Schönemann Peter H. , Wang Ming Mei
Published: February 2006

A model for the analysis of paired comparison data is presented which combines features of the BTL-model with features of the Unfolding model. The model is metric, mathematically tractable, and has an exact algebraic solution. Since it is multidimensional and allows for individual differences, it is thought to be more realistic for some choice situations than either the Thurstone model or the BTL-model. No claim is made that the present model will be appropriate for all conceivable choice situations. Rather, it is argued that the fact that it is explicitly falsifiable is a point in its favor.
The Effects of Selection in Factor Analysis
Authors: Thurstone L. L.
Published: February 2006

Factorial results are affected by selection of subjects and by selection of tests. It is shown that the addition of one or more tests which are linear combinations of tests already in a battery causes the addition of one or more incidental factors. If the given test battery reveals a simple structure, the addition of tests which are linear combinations of the given tests leaves the structure unaffected unless the number of incidental factors is so large that the common factors become indeterminate.
Testing Linear Hypotheses Illustrated by a Simple Example in Correlation
Authors: Hoyt Cyril J.
Published: February 2006

The development of a criterion suitable for testing the significance of a correlation or regression coefficient is used as an illustration of the manner in which a research problem is bound to the selection of the particular data appropriate to collect and a fitting type of statistical analysis of the latter. The translation of the original inquiry into a problem of “testing linear hypotheses” is the means by which these two aspects of an investigation are held together. This presentation is offered as a plan which might be useful for some research workers in determining appropriate criteria for testing their particular hypotheses.
The Usability of the Concept of “Prejudice”
Authors: Dyer Henry S.
Published: February 2006

For the purpose of determining whether the trait concept of “prejudice” is usable in the communication of meaning, representative samples of the responses of 101 ninth-grade children were submitted to a diverse group of 20 judges who were requested to rank 11 series of the responses in accordance with the amount of prejudice they were judged to exhibit. The usability, or use-value, of the concept is conceived as the extent to which the judges can agree in their ratings and is expressed in terms of the average intercorrelation of such ratings. It is shown that a null hypothesis of no use-value (\documentclass[12pt]{minimal}
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Coefficient Alpha and the Internal Structure of Tests
Authors: Cronbach Lee J.
Published: February 2006

A general formula (α) of which a special case is the Kuder-Richardson coefficient of equivalence is shown to be the mean of all split-half coefficients resulting from different splittings of a test. α is therefore an estimate of the correlation between two random samples of items from a universe of items like those in the test. α is found to be an appropriate index of equivalence and, except for very short tests, of the first-factor concentration in the test. Tests divisible into distinct subtests should be so divided before using the formula. The index \documentclass[12pt]{minimal}
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Estimation of Other Coefficients of Correlation from the Phi Coefficient
Authors: Guilford J. P. , Perry Norman C.
Published: February 2006

Formulas are developed for estimating a point-biserial r or a tetrachoric r from an obtained phi coefficient. The estimate of a tetrachoric r, which is called rϕ, is shown to be equivalent to that obtained from first-order use of the tetrachoric r series. A tabulation is made of corrections needed to make rϕ equivalent numerically to the tetrachoric r. In spite of its greater generality than estimates of tetrachoric r by previous methods, there are limitations, which are pointed out.
Analysis of Individual Differences in Multidimensional Scaling Via an N-way Generalization of “Eckart-Young” Decomposition
Authors: Carroll J. Douglas , Chang Jih-Jie
Published: February 2006

An individual differences model for multidimensional scaling is outlined in which individuals are assumed differentially to weight the several dimensions of a common “psychological space”. A corresponding method of analyzing similarities data is proposed, involving a generalization of “Eckart-Young analysis” to decomposition of three-way (or higher-way) tables. In the present case this decomposition is applied to a derived three-way table of scalar products between stimuli for individuals. This analysis yields a stimulus by dimensions coordinate matrix and a subjects by dimensions matrix of weights. This method is illustrated with data on auditory stimuli and on perception of nations.
On Metric Multidimensional Unfolding
Authors: Schönemann Peter H.
Published: February 2006

The problem of locating two sets of points in a joint space, given the Euclidean distances between elements from distinct sets, is solved algebraically. For error free data the solution is exact, for fallible data it has least squares properties.
The Analysis of Categorizing Behavior
Authors: Evans Glen T.
Published: February 2006

Latent partition analysis enables an examination of the modal population categorizations of a set of items. The initial model proposed by Wiley is reformulated, extended and generalized. Firstly, the effects of judges are regarded as random, rather than fixed. In a second model, several latent partitions, rather than one, are allowed, resulting in a type of multidimensional approach. Finally, both the single and multiple partition models are shown to be specializations of a less restrictive model, called the category focusing model. In each of these three cases, properties implicit in the model are used to derive appropriate solution procedures.

Measures of individual differences are considered, and the application of the procedure to experimental work in concept formation is discussed. Several sets of data are used to demonstrate the characteristics of the techniques evolved.
Free amino acid concentrations in blood cells of two brothers with gyrate atrophy of the choroid and retina with hyperornithinaemia
Authors: Fukuda K. , Nishi Y. , Usui T. , Mishima H. , Hirata H. , Baba S. , Choshi K. , Tanaka Y. , Akiya S.
Published: February 2006

In this study we selected blood cells as accessible tissues and measured the free amino acid concentrations in erythrocytes, lymphocytes, and granulocytes of two patients with gyrate atrophy with hyperornithinaemia. We found that ornithine concentrations were elevated in blood cells, to different degrees depending on the type of cell, and that aspartic acid concentrations were low in erythrocytes. We also investigated the fluctuation of free amino acid concentrations in blood cells up to 24h after the oral administration of ornithine. The ornithine concentration in the blood cells of the patients reached a peak 2 h after the oral administration, and remained high for at least 4 h, although after 2 h the concentration curves differed in the three types of cells.
Immunological evidence for an ornithine transcarbamylase lesion resulting in the formation of enzyme with smaller protein subunits
Authors: Hoogenraad N. , Luisa de Martinis M. , Danks D. M.
Published: February 2006

An unusual form of ornithine transcarbamylase deficiency was found in a male child who became unconscious at 8 months. Two maternal uncles had died during similar illnesses at 6 years and 11 years, respectively. Detailed studies of the enzyme showed 10% residual activity, a very lowKm for carbamyl phosphate (0.015 mmol/l) and near normal amounts of immunoreactive protein with a smaller than normal subunit (molecular weight 37 800 instead of 39 700). This information was obtained from a 10 mg liver biopsy core using protein separation on SDS‐polyacrylamide gel, electrophoretic transfer to nitrocellulose filters and probing with antibody to the enzyme. Resolution of the exact mutation causing this change will be of interest to those who are studying the processing of mitochondrial enzymes during transport from the cytoplasm.
The simple detection of neuraminic acid‐containing urinary oligosaccharides in patients with glycoprotein storage diseases
Authors: Sewell A. C.
Published: February 2006

Urine samples from patients with different types of glycoprotein storage disease were chromatographed by gel filtration and the fractions analysed for sialic acid. Patients with mucolipidoses I and II excreted the largest amounts of bound sialic acid. One patient with GM1 gangliosidosis showed an abnormal level of sialyloligosaccharide excretion. Other patients showed normal results. With the present method mucolipidoses I and II, together with GM1 gangliosidosis, are readily distinguished from other possible oligosaccharidurias.
Increased sensitivity of cerebrohepatorenal syndrome fibroblasts to antimycin A
Authors: Kelley R. I. , Corkey B. E.
Published: February 2006

The effect of four mitochondrial electron transport inhibitors on the growth of normal and cerebrohepatorenal syndrome (CHRS) fibroblasts was studied. Compared to normal fibroblasts, CHRS cells demonstrated a fivefold greater sensitivity to antimycin A, an inhibitor of the cytochrome bc1 complex (complex III), but equal inhibition by amytal, rotenone and 2‐heptyl‐4‐hydroxyquinoline‐N‐oxide. The results suggest a primary or secondary functional deficiency at mitochondrial complex III in fibroblasts.