bluuebunny/crossref_metadata_2025 huggingface dataset:
Errors in response calculations for beams
Authors: Wada H. , Warburton G. B.
Published: March 2007

When the finite element method is used to idealize a structure, its dynamic response can be determined from the governing matrix equation by the normal mode method or by one of the many approximate direct integration methods. In either method the approximate data of the finite element idealization are used, but further assumptions are introduced by the direct integration scheme. It is the purpose of this paper to study these errors for a simple structure. The transient flexural vibrations of a uniform cantilever beam, which is subjected to a transverse force at the free end are determined by the Laplace transform method. Comparable responses are obtained for a finite element idealization of the beam, using the normal mode and Newmark average acceleration methods; the errors associated with the approximate methods are studied. If accuracy has priority and the quantity of data is small, the normal mode method is recommended; however, if the quantity of data is large, the Newmark method is useful.
Flexural responses of grouped piles under dynamic loading
Authors: Nogami Toyoaki
Published: March 2007

A simple approach to analyse the flexural vibration of grouped piles was developed. In this approach, a pile group is replaced by a single pile for the evaluation of the pile‐head flexibility matrix. Parametric studies were conducted for various conditions of grouped piles. Various features of flexural vibration of pile groups were found. The charts presented in this paper enable quick estimations of dynamic group effects to be made in a manner similar to that widely used for the evaluation of static group effects.
Inelastic analysis of R/C coupled shear walls
Authors: Keshavarzian M. , Schnobrich W. C.
Published: March 2007

This paper presents a method of analysis capable of calculating the response of an R/C coupled shear wall structure subjected to strong earthquake motion without major complications existing in the method itself. The relative simplicity is achieved while retaining reasonable reliability in the computed response. The reliability of the computed results are tested against 1‐ the measured responses of a cantilever column member and a 6‐storey coupled shear wall system under static cyclic lateral loads; and 2‐ the measured responses of two coupled shear wall structures which were subjected to simulated earthquake motions on the University of Illinois Earthquake Simulator. The effects of moment‐axial force interaction in the wall members on the computed overall responses of the coupled shear wall structures and on the behaviour of each individual wall are discussed.
Analysis of the spatial variation of seismic waves and ground movements from smart‐1 array data
Authors: Loh Chin‐Hsiung
Published: March 2007

Specially designed arrays of strong motion seismographs located near earthquake sources are required for engineering studies of the near‐source properties and the spatial variation of seismic waves. The SMART‐1 array in Taiwan provides good records for this type of study. Careful study of the observed strong motion data permits the identification of wave types, directions and apparent wave velocities. In this paper, a principal direction ratio R (f,α) is defined; this indicates the principal direction of the motion (along a nearly straight line) within the range 0 < R < 1. Vertical motion of the ground is also included in this study. Orbit spectrum analysis is used to verify the identification of wave directions and wave types.

The spatial variation of seismic waves along the principal direction is studied. From frequency‐domain analysis, mathematical models of the spatial variation of ground displacement are developed using a wave‐number spectrum and the cross‐spectral density function between two spatial coordinates; these models in turn can provide two alternative models for the random vibration analysis of extensive structures subject to multiple point seismic excitation. The SMART‐1 array data gathered during the January 29, 1981 earthquake also are used to demonstrate calculation of the ground strains and differential movements of the array site.

From time‐domain analysis, the spatial variation of seismic waves is defined for ground motion along the identified principal direction. The time variation of evolutionary spectra characterized by frequency‐dependent parameters is used for this formulation. The SMART‐1 array data again form the basis for discussion of the spatial variation of model parameters.
Influence of foundation flexibility on soil‐structure interaction
Authors: Riggs H. R. , Waas G.
Published: March 2007

The effect of the base mat flexibility on seismic soil‐structure interaction is studied for an axisymmetric reactor building on a soft and a stiff soil. As a preliminary step, the dynamic response of a massless flexible circular plate with two rigid concentric walls, through which the plate is loaded, is analysed.

The response of the plate is found to depend on the plate flexibility, the load distribution and the frequency of excitation. For practical, in‐phase load distributions, the response of the flexible plate is close to that of a rigid plate at low frequencies, but deviates at high frequencies.

Including the flexibility of the mat has hardly any effect on the frequencies and damping of the fundamental rocking and vertical modes of the reactor building. This is the case for soft and stiff soil conditions. However, the flexibility of the mat strongly affects the first and higher structural deformation modes. In both cases the amount of energy dissipated in the soil is a significant percentage of the total dissipation, and is essentially unaffected by the mat flexibility.
An evaluation of a class of practical optimization techniques for structural dynamics applications
Authors: Masri S. F. , Werner S. D.
Published: March 2007

This paper evaluates a class of practical optimization techniques for parameter identification of realistic structural dynamic systems. The techniques involve quasi‐Newton methods together with an efficient procedure for estimating complicated error functions. The optimization procedures are verified through their application to several representative examples, including finite‐element models of realistic structural systems. Extensive numerical and graphical results demonstrate the effects of various optimization algorithm parameters on the rate of convergence of the objective function, the parameter vector error norm and the gradient norm. Guidelines are presented as an aid for addressing several significant issues in the practical application of structural dynamics optimization procedures, such as sensitivity problems, uniqueness, initial value definition for the parameter vector, convergence rates, constraints, the effect of alternative cost function definitions, accuracy of alternative gradient evaluation procedures, alternative procedures for estimating the inverse of the Hessian matrix and the use of a quadratic approximation of the objective function.
Dynamic characteristics of soil‐foundation interaction system detected from forced vibration test and earthquake observation
Authors: Ishida Katsuhiko
Published: March 2007

This paper presents some results on the following subjects obtained from in‐situ forced vibration tests and earthquake observations. (1) The characteristics of the radiation damping of soil‐foundation interaction systems vs. non‐dimensional frequency a0 (=ωr/Vs) were experimentally estimated by the equivalent damping ratios hH ( = K′H/2KH) and hR ( = K′R/2KR), which were defined by complex stiffnesses 1KH (= KH + iKH) and 1KR (= KR + iK′R) of soil. The results for hH and hR of base rock were compared with those of soft soil. (2) A comparative study of experimental and theoretical results was made. The theoretical results were obtained from elastic half‐space theory. (3) A semi‐empirical equation to estimate the equivalent S‐wave velocity for the elastic half‐space model is proposed here, considering the effects of layered media. (4) Various comparisons of the results of 1 KH, 1 KR, hH and hR of forced vibration tests and earthquake observations were made.
Seismic shear vibration of embankment dams in semi‐cylindrical valleys
Authors: Dakoulas Panos , Gazetas George
Published: March 2007

A rigorous analytical solution is developed for the lateral linear shear response of embankment dams in semi‐cylindrical valleys. Closed‐form algebraic expressions are presented pertaining to both free and base‐induced oscillations, and extensive parametric and comparative studies elucidate the prominent effects of canyon geometry (shape and aspect ratio) on dynamic response. Harmonic steady‐state as well as earthquake‐induced accelerations, displacements and shear strains in the dam are studied and compared with those obtained from 3‐Dimensional analyses for other canyon geometries, as well as from 2‐Dimensional (2‐D) analyses of the dam mid‐section. It is shown that such 2‐D analyses may provide significantly lower values of near‐crest accelerations, but slightly higher values of shear strains and stresses than the 3‐D analyses. The proposed method of analysis is at least three orders of magnitude less expensive than other presently available numerical procedures.
Non‐linear soil–structure interaction analysis based on the boundary‐element method in time domain with application to embedded foundation
Authors: Wolf John P. , Darbre Georges R.
Published: March 2007

The various boundary‐element methods, well established in the frequency domain, are developed in the time domain for a foundation embedded in a layered halfspace. They are the weighted‐residual technique and the indirect boundary‐element method, based on a weighted‐residual equation, and the direct boundary‐element method based on a reciprocity equation, both equations involving time and space. In the indirect approach, formulating the weighted‐residual equation over the last time step only results in the truncated indirect boundary‐element formulation which requires a reduced computational effort. In all cases, convolution integrals occur.

The truncated indirect boundary‐element method leads to a highly reliable algorithm, as is verified when a linear analysis in the time domain is compared to the corresponding one in the frequency domain. This boundary‐element formulation, which is non‐local in space and time, represents a rigorous generally applicable method taking into account a layered halfspace in a non‐linear soil‐structure interaction analysis.

As an example, the non‐linear soil‐structure interaction analysis of a structure embedded in a halfspace with partial uplift of the basemat and separation of the side wall is investigated.
Errors in response calculations for extensional vibrations of bars
Authors: Wada H.
Published: March 2007

The transient extensional vibrations of a slender and uniform bar, which is clamped at one end and is subjected to an axial force at the other free end, are investigated by applying three methods: the Laplace transform method, the normal mode and Newmark β methods in conjunction with the finite element method (FEM); the errors caused by the spatial discretization of the FEM and the direct integration of the Newmark β method are studied and compared with those of the previous paper where the flexural vibrations of a cantilever beam were considered. The reason why the extensional vibration problem is investigated here is that the condition seems to be severe due to the closeness of adjacent natural frequencies, the larger values of natural frequencies and the smaller number of nodal variables of the FEM in comparison with those of the flexural vibration problem. The numerical results show that the errors in response of the extensional vibration problem are large. However, if one follows the criterion proposed in this paper, accurate response is obtainable by the Newmark β method, which requires less computer time than either of the other methods mentioned above.
Earthquake response spectra taking account of number of response cycles
Authors: Kawashima Kazuhiko , Aizawa Koh
Published: March 2007

Proposed is a new definition of earthquake response spectra, which takes account of the number of response cycles N. The Nth largest amplitude of absolute acceleration response of a linear oscilator with natural period T and damping ratio h, which is subjected to ground motion at its base, is defined as SA(T, h, N). By defining a reduction factor η(T, h, N) as SA(T, h, N)/SA(T, h, 1), characteristics of η(T, h, N) were investigated based on 394 components of strong motion records obtained in Japan. Two practical empirical formulae to assess the reduction factor η(T, h, N) are proposed.
Attenuation of peak ground acceleration, velocity and displacement based on multiple regression analysis of japanese strong motion records
Authors: Kawashima Kazuhiko , Aizawa Koh , Takahashi Kazuyuki
Published: March 2007

This paper presents the result of multiple regression analysis of 197 sets of two orthogonal horizontal strong motion acceleration records. They were obtained at 67 free field sites in Japan from 90 earthquakes with focal depth less than 60 km. Because sensitivity of the Japanese SMAC accelerograph is appreciably low at the high frequency range, instrument correction was performed on the original data. Each pair of two orthogonal horizontal components was combined in the time domain to get the maximum peak ground motions in the horizontal plane.

The records were classified into three groups due to subsoil condition. With the use of multiple regression analysis, empirical formulae of attenuation of the maximum peak ground acceleration, velocity and displacement were proposed for three subsoil conditions.
Developing a parenting skills‐and‐support intervention for mothers with eating disorders and pre‐school children part 1: qualitative investigation of issues to include
Authors: Bryant‐Waugh Rachel , Turner Hannah , East Philippa , Gamble Caroline
Published: March 2007

Objective

This study aimed to (i) identify themes and issues that might usefully be addressed in a skills‐and‐support intervention for mothers with eating disorders who have children less than 5 years of age, and (ii) determine the most appropriate format for such an intervention.

Method

Focus groups and individual interviews were conducted with seven mothers with eating disorders and pre‐school children, and four local health professionals working with mothers of pre‐school children.

Results

Thematic analysis of interview transcripts revealed 10 themes: ‘Passing on Traits’, ‘Food Preparation and Provision’, ‘Interactions Around Food and Mealtimes’, ‘Mother's Intake’, ‘Self Care’, ‘Self Identity and Parental Expectations’, ‘Impact on General Parent–Child Relationship’, ‘Need for Control’, ‘The Group Experience’ and ‘Practicalities and Format’.

Discussion

Findings highlight a number of difficulties and concerns experienced by mothers with eating disorders who have pre‐school age children. An intervention incorporating the identified themes could provide important support to this patient group and potential benefit to their offspring. © 2007 John Wiley & Sons, Ltd and Eating Disorders Association.
Lysyl oxidase‐like 2 expression is increased in colon and esophageal tumors and associated with less differentiated colon tumors
Authors: Fong Sheri F. T. , Dietzsch Erin , Fong Keith S. K. , Hollosi Peter , Asuncion Lloyd , He QingPing , Parker M. Iqbal , Csiszar Katalin
Published: March 2007

Lysyl oxidase‐like 2 (LOXL2) belongs to an amine oxidase family whose members have been implicated in crosslink formation in stromal collagens and elastin, cell motility, and tumor development and progression. We previously demonstrated the association between increased LOXL2 expression and invasive/metastatic behavior in human breast cancer cells and mouse squamous and spindle cell carcinomas, interaction between LOXL2 and SNAIL in epithelial‐mesenchymal transition, and localization of the LOXL2 gene to 8p21.2–21.3, within a minimally deleted region in several cancers, including colon and esophagus. In the present study, we analyzed LOXL2 expression in colon and esophageal tumors, and explored methylation as a regulator of LOXL2 expression. Immunohistochemistry using normal tissues demonstrated intracellular localization of LOXL2 in colonic enteroendocrine cells and esophageal squamous cells at the luminal surface, but not in mitotically active cells. Tissue array analysis of 52 colon adenocarcinomas and 50 esophageal squamous cell carcinomas revealed presence of LOXL2 expression in 83 and 92% of the samples, respectively, and a significant association between increased number of LOXL2‐expressing cells and less‐differentiated colon carcinomas. We determined that the methylation status of the 1150 bp 5′ CpG island may contribute to the regulation of the gene. Loss of heterozygosity studies, using a microsatellite within intron 4 of the LOXL2 gene, revealed that loss of LOXL2 was unlikely to play a major role in either colon or esophageal tumors. These results suggest that increased LOXL2 expression in colon and esophageal cancer may contribute to tumor progression. © 2007 Wiley‐Liss, Inc.
An examination of groundwater within the Hawara Pyramid, Egypt
Authors: Keatings K. , Tassie G.J. , Flower R.J. , Hassan F.A. , Hamdan M.A.R. , Hughes M. , Arrowsmith C.
Published: March 2007

The Hawara Pyramid is an outstanding monument. However, the mudbrick structure shows signs of erosion, and the passages and chambers are currently submerged. The problem of water ingress has mainly arisen since the 1880s. In this study, an initial assessment of the pyramid structure was made and causes of water ingress were investigated through analysis of water samples. Stable oxygen isotope measurements indicate that the source of water within the pyramid is the Bahr Selah canal. Water within the pyramid is highly saline compared to the Bahr Selah, and evaporation can only partly account for this high salinity. The composition of dissolved ions suggests that dissolution of salts in soils and from bedrock in the vicinity of the pyramid has enhanced the salinity of water percolating into the pyramid structure. Water ingress and salt deposition are at present the main threat to the integrity of the monument. © 2007 Wiley Periodicals, Inc.
Subthreshold depression in patients with Parkinson's disease and dementia––clinical and demographic correlates
Authors: Ehrt Uwe , Brønnick Kolbjørn , De Deyn Peter Paul , Emre Murat , Tekin Sibel , Lane Roger , Aarsland Dag
Published: March 2007

Background

About 40% of the patients with Parkinson's disease (PD) have depressive symptoms, either major depression (MD) or subthreshold depression. Depression was found to be associated with age and age at onset of PD, female gender, more severe parkinsonism, in particular with left‐sided and akinetic‐rigid symptoms, more functional impairment and cognitive impairment.

However, the findings are inconsistent and partly contradictory and most of the studies focused on major depression in PD without dementia.

The aim of this study was to examine the relationship between subthreshold depression and other clinical features in 538 PD patients with dementia but without MD drawn from a randomized, placebo‐controlled multicentre trial of rivastigmine in PD.

Results

One hundred and sixteen patients (21%) had subthreshold depression. Depression was associated with a younger age and age at onset and female gender, but not with severity of parkinsonism, cognition or activities of daily living or laterality of motor symptoms. However, in male patients, an association between depression and left‐sided parkinsonism was found.

Conclusion

In contrast to previous findings in PD patients with major depression but without dementia, we found no relationship between subthreshold depression and other clinical symptoms in patients with PDD. Copyright © 2007 John Wiley & Sons, Ltd.
A cluster randomised controlled trial to reduce the unmet needs of people with dementia living in residential care
Authors: Orrell Martin , Hancock Geraldine , Hoe Juanita , Woods Bob , Livingston Gill , Challis David
Published: March 2007

Background

Older people with dementia living in residential care have complex unmet needs and decreased quality of life.

Aim

To reduce unmet needs in older people with dementia in residential care compared to a ‘care as usual’ control group.

Method

A single blind, multicentre, cluster randomised controlled trial recruited 238 people aged 60+ with dementia living in 24 residential homes from three areas. Unmet needs were measured using the Camberwell Assessment of Needs for the Elderly (CANE) and quality of life using the Quality of Life in Alzheimer's Disease (QoL‐AD). Homes were randomised to the control (care as usual) or the intervention group 1 hour per week liaison input per home to deliver a personalised intervention package over a 20 weeks to meet the unmet needs.

Results

A single blind follow‐up included 192 (81%) available participants. At follow‐up the total number of unmet needs was reduced in both the intervention and control groups, but analysing the groups by clusters there were no significant differences in either unmet needs or quality of life.

Conclusions

The unmet needs of people with dementia can be identified using the CANE. The CANE assessment may have led to unmet needs being reduced at follow up, but the liaison intervention did not significantly reduce total unmet needs relative to the control group. Unmet needs such as sensory problems, mobility, drugs, and psychological distress were especially reduced in the intervention group at follow up. Copyright © 2007 John Wiley & Sons, Ltd.
A new computer program for QSAR‐analysis: ARTE‐QSAR
Authors: Damme Sofie Van , Bultinck Patrick
Published: March 2007

A new computer program has been designed to build and analyze quantitative–structure activity relationship (QSAR) models through regression analysis. The user is provided with a range of regression and validation techniques. The emphasis of the program lies mainly in the validation of QSAR models in chemical applications. ARTE‐QSAR produces an easy interpretable output from which the user can conclude if the obtained model is suitable for prediction and analysis. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007.
Modifications in chromatin morphology and organization during sheep oogenesis
Authors: Russo Valentina , Martelli Alessandra , Berardinelli Paolo , Di Giacinto Oriana , Bernabò Nicola , Fantasia Donatella , Mattioli Mauro , Barboni Barbara
Published: March 2007

This research has been designed to study the major events of nuclear remodeling that characterize sheep oocytes during the early stage of folliculogenesis (transition from preantral to antral stage). In particular, the modifications in large‐scale chromatin configuration, the global DNA methylation, and the process of telomere elongation have been investigated as crucial events of oocyte nuclear maturity. In addition, the spatio‐temporal distribution of the major enzymes involved in DNA methylation, the DNA methyltransferase 1 (Dnmt1), and in telomere elongation, telomerase catalytic subunit (TERT), have been described. To these aims, the nuclei of isolated oocytes were investigated using immunocytochemistry and Q‐FISH analyses. In absence of preliminary information, these nuclear determinants were compared with those of fully competent germ cells obtained from medium and preovulatory antral follicles. The nuclei of sheep oocytes acquired a condensed chromatin configuration, stable high levels of global DNA methylation, and a definitive telomere length already in the majority of late growing stage oocytes (110 μm) derived from early antral follicles. In addition, while the process of methylation resulted strictly related to oocyte diameter, the telomeric program appeared to be highly chromatin configuration‐dependent. The translocation of Dnmt1 and TERT from the nucleus to the cytoplasm in the oocytes derived from early antral follicles seems to confirm the definitive chromatin asset of these germ cells. In conclusion, changes in large‐scale chromatin structure, epigenesis, and telomere size in the sheep are established prior to oocyte acquires the ability to resume meiosis. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Tutte sets in graphs I: Maximal tutte sets and D‐graphs
Authors: Bauer D. , Broersma H. J. , Morgana A. , Schmeichel E.
Published: March 2007

A well‐known formula of Tutte and Berge expresses the size of a maximum matching in a graph G in terms of what is usually called the deficiency of G. A subset X of V(G) for which this deficiency is attained is called a Tutte set of G. While much is known about maximum matchings, less is known about the structure of Tutte sets. In this article, we study the structural aspects of maximal Tutte sets in a graph G. Towards this end, we introduce a related graph D(G). We first show that the maximal Tutte sets in G are precisely the maximal independent sets in its D‐graph D(G), and then continue with the study of D‐graphs in their own right, and of iterated D‐graphs. We show that G is isomorphic to a spanning subgraph of D(G), and characterize the graphs for which G≅D(G) and for which D(G)≅D2(G). Surprisingly, it turns out that for every graph G with a perfect matching, D3(G)≅D2(G). Finally, we characterize bipartite D‐graphs and comment on the problem of characterizing D‐graphs in general. © 2007 Wiley Periodicals, Inc. J Graph Theory 55: 343–358, 2007
Tough spiders
Authors: Kaiser Tomáš , Král Daniel , Stacho Ladislav
Published: March 2007

Spider graphs are the intersection graphs of subtrees of subdivisions of stars. Thus, spider graphs are chordal graphs that form a common superclass of interval and split graphs. Motivated by previous results on the existence of Hamilton cycles in interval, split and chordal graphs, we show that every 3/2‐tough spider graph is hamiltonian. The obtained bound is best possible since there are (3/2 – ε)‐tough spider graphs that do not contain a Hamilton cycle. © 2007 Wiley Periodicals, Inc. J Graph Theory 56: 23–40, 2007
T‐joins intersecting small edge‐cuts in graphs
Authors: Kaiser Tomáš , Škrekovski Riste
Published: March 2007

In an earlier paper 3, we studied cycles in graphs that intersect all edge‐cuts of prescribed sizes. Passing to a more general setting, we examine the existence of T‐joins in grafts that intersect all edge‐cuts whose size is in a given set A ⊆{1,2,3}. In particular, we characterize all the contraction‐minimal grafts admitting no T‐joins that intersect all edge‐cuts of size 1 and 2. We also show that every 3‐edge‐connected graft admits a T‐join intersecting all 3‐edge‐cuts. © 2007 Wiley Periodicals, Inc. J Graph Theory 56: 64–71, 2007
Engineering molecular recognition of endoxylanase enzymes and their inhibitors through phage display
Authors: Beliën Tim , Van Campenhout Steven , Bosch An Vanden , Bourgois Tine M. , Rombouts Sigrid , Robben Johan , Courtin Christophe M. , Delcour Jan A. , Volckaert Guido
Published: March 2007

Specific binding of interacting proteins generally depends on a limited set of amino acid residues located at the contact interface. We have applied a phage‐display‐based screening method to simultaneously evaluate the role of multiple residues of endo‐β‐1,4‐xylanase enzymes in conferring binding specificity towards two different endoxylanase inhibitors. Seven residues of the two β‐strand ‘thumb’ region of Trichoderma longibrachiatum endo‐β‐1,4‐xylanase XynII were targeted for randomization. The generated combinatorial library representing 62 208 site‐directed variants was displayed on the surface of filamentous phage and selected against xylanase inhibitor protein (XIP) and Triticum aestivum xylanase inhibitor (TAXI). DNA sequence analysis of phagemid panning isolates provided information on the occurrence of particular amino acids at distinct positions. In particular, residues at positions 124 (Asn) and 131 (Thr) were found to be critical for specific inhibitor binding. These residue predictions derived from the combinatorial exploration of the thumb region and accompanying sequence analyses were experimentally confirmed by testing the inhibitor sensitivity of a limited set of recombinantly expressed XynII mutants. In addition, we successfully altered the inhibition susceptibility of the bacterial Bacillus subtilis endoxylanase XynA from XIP‐insensitive to XIP‐sensitive. Copyright © 2007 John Wiley & Sons, Ltd.
Analysis of flavor and perfume using an internally cooled coated fiber device
Authors: Chen Yong , Begnaud Frédéric , Chaintreau Alain , Pawliszyn Janusz
Published: March 2007

A miniaturized internally cooled coated fiber device was applied for the analysis of flavors and fragrances from various matrices. Its integration with a CTC CombiPAL autosampler enabled high throughput for the analysis of analytes in complex matrices that required simultaneous heating of the matrices and cooling of the fiber coating to achieve high extraction efficiency. It was found that up to ten times increase of extraction efficiencies was observed when the device was used to extract flavor compounds in water, even when limited sample temperatures were used to preserve the integrity of target compounds. The extraction of the flavor compounds in water with the device was reproducible, with RSD not larger than 15%. The lower limits of the linear ranges were in the low ppb range, which was about one order of magnitude smaller than those obtained with the commercialized 100 μm PDMS fibers. Exhaustive extraction of some perfume ingredients from a complex matrix (shampoo) was realized. All achieved recoveries were not less than 80%. The repeatability of the extraction of the perfume compounds from shampoo was better than 10%. The linear ranges were about 1–3000 μg/g, and the LOD was about 0.2–1 μg/g. The automated internally cooled coated fiber device was demonstrated to be a powerful sample preparation tool in flavor and fragrance analysis.
Exploring solvent versatility in immobilized cellulose‐based chiral stationary phase for the enantioselective liquid chromatographic resolution of racemates
Authors: Ghanem Ashraf
Published: March 2007

Chiralpak IB, a new chiral stationary phase (CSP) containing cellulose tris(3,5‐dimethylphenylcarabamate) immobilized onto silica gel, is investigated for the direct enantioselective separation of a set of racemic N‐alkylated barbiturates and analogs of thalidomide alkylated in position 3 of the piperidin‐2,6‐dione ring using different nonstandard solvents such as dichloromethane (DCM), ethyl acetate, THF, methyl tert‐butyl ether as an eluent and diluent, respectively, in HPLC. The separation, resolution, and elution order of the investigated compounds were compared on both immobilized and coated cellulose tris(3,5‐dimethylphenylcarbamate) CSPs (Chiralpak IB and Chiralcel OD, respectively) using a mixture of n‐hexane/2‐propanol (90:10 v/v) as mobile phase with different flow‐rates and fixed UV detection at 254 nm. The effect of the immobilization of the cellulose tris‐(3,5‐dimethylphenylcarbamate) CSP on silica (Chiralpak IB) on the chiral recognition ability was noted as the coated phase (Chiralcel OD) possesses a higher resolving power in some cases than the immobilized one (Chiralpak IB). However, a few racemates, which were not or poorly resolved on the immobilized Chiralpak IB or the coated Chiralcel OD when using standard solvents were most efficiently resolved on the immobilized Chiralpak IB upon using nonstandard solvents. Furthermore, the immobilized phase withstands the nonstandard (prohibited) HPLC solvents mentioned previously when used as eluents or as a dissolving agent for the analyte itself. An example of inversion or apparent inversion of elution order on Chiralpak IB is reported. The direct analysis of a spiked plasma sample extracted using DCM on Chiralpak IB is also shown.
Recipient and Donor Factors Influence the Incidence of Graft-Vs.-Host Disease in Liver Transplant Patients
Authors: Chan Edie Y. , Larson Anne M. , Gernsheimer Terry B. , Kowdley Kris V. , Carithers Robert L. , Reyes Jorge D. , Perkins James D.
Published: March 2007

Acute cellular graft-vs.-host disease (GVHD) following liver transplantation has an incidence of 1 to 2% and a mortality rate of 85%. Our aim was to identify a patient population at high risk for developing GVHD using a large clinical database to study both recipient and donor factors. We compared our liver transplant patients who developed GVHD to those that did not for recipient and donor factors and combinations of factors. For 2003–2004 we had 205 first-time liver transplant patients surviving >30 days. From this group, 4 (1.9%) developed GVHD. Compared to the control group, there were no significant differences in recipient age, recipient gender, donor age, donor gender, total ischemia time, donor-recipient human leukocyte antigen (HLA) mismatch, or donor-recipient age difference. Percentages of liver disease etiologies among the patients who developed GVHD were as follows: 16% (1/6) autoimmune hepatitis (AIH) (P = 0.003), 5.6% (3/54) alcoholic liver disease (ALD) (P = 0.057), and 7.1% (3/42) hepatocellular carcinoma (HCC) (P = 0.026). The incidence of GVHD in patients with glucose intolerance (either Type I or Type II diabetes mellitus [DM]) was significant (P = 0.022). Focusing on patients only with high-risk factors for GVHD during the years 2003–2005, we had 19 such patients. Four of these high-risk patients developed GVHD. Three of these 4 patients had received a donor liver with steatosis of degree ≥mild compared to only 2 of the 15 high-risk patients who did not develop GVHD (P = 0.037). In conclusion, we have identified liver transplant patients with AIH or the combination of ALD, HCC, and glucose intolerance who receive a steatotic donor liver as being at high risk for developing GVHD. Liver Transpl 13:516–522, 2007. © 2007 AASLD.
Functional and Morphological Comparison of Three Primary Liver Cell Types Cultured in the AMC Bioartificial Liver
Authors: Poyck Paul P.C. , Hoekstra Ruurdtje , van Wijk Albert C.W.A. , Attanasio Chiara , Calise Fulvio , Chamuleau Robert A.F.M. , van Gulik Thomas M.
Published: March 2007

The selection of a cell type for bioartificial liver (BAL) systems for the treatment of patients with acute liver failure is in part determined by issues concerning patient safety and cell availability. Consequently, mature porcine hepatocytes (MPHs) have been widely applied in BAL systems. The success of clinical BAL application systems is, however, largely dependent on the functionality and stability of hepatocytes. Therefore, we compared herein the general metabolic and functional activities of MPHs with mature human hepatocytes (MHHs) in the Academic Medical Center (AMC)-BAL during a 7-day culture period. We also tested fetal human hepatocytes (FHHs), since their proliferation capacity is higher than MHHs and their function is increased compared to human liver cell lines. The results showed large differences between the 3 cell types. MHHs eliminated 2-fold more ammonia and produced 3-fold more urea than MPHs, whereas FHHs produced ammonia. Lidocaine elimination of FHHs was 3.5-fold higher than MPHs and 6.6-fold higher than of MHHs. Albumin production was not different between the 3 cell types. MPHs and FHHs became increasingly glycolytic, whereas MHHs remained metabolically stable during the whole culture period. MHHs and MPHs formed tissue-like structures inside the AMC-BAL. In conclusion, we propose that FHHs can be considered as a suitable cell type for pharmacological studies inside a bioreactor. However, we conclude that MHHs are the preferred cell source for loading a BAL device for clinical use, because of their high ammonia eliminating capacity and metabolic stability. MPHs should be considered as the best alternative cell source for BAL application, although their phenotypic instability urges application within 1 or 2 days after loading. Liver Transpl 13:589–598, 2007. © 2007 AASLD.
B-Cell Surface Marker Analysis for Improvement of Rituximab Prophylaxis in ABO-Incompatible Adult Living Donor Liver Transplantation
Authors: Egawa Hiroto , Ohmori Katsuyuki , Haga Hironori , Tsuji Hiroaki , Yurugi Kimiko , Miyagawa-Hayashino Aya , Oike Fumitaka , Fukuda Akinari , Yoshizawa Jun , Takada Yasutsugu , Tanaka Koichi , Maekawa Taira , Ozawa Kazue , Uemoto Shinji
Published: March 2007

Although the effectiveness of rituximab has been reported in ABO blood group (ABO)-incompatible (ABO-I) organ transplantation, the protocol is not yet established. We studied the impact of the timing of rituximab prophylaxis and the humoral immune response of patients undergoing ABO-I living donor liver transplantation (LDLT), focusing on clinicopathological findings and the B-cell subset. From July 2003 to December 2005, 30 adult patients were treated with hepatic artery infusion (HAI) protocol without splenectomy for ABO-I LDLT. A total of 17 patients were treated only with HAI (no prophylaxis), and the other 13 were treated with rituximab prophylaxis at various times prior to transplantation. For B-cell study of the spleen, another 4 patients undergoing ABO-I LDLT both with HAI after prophylaxis and eventual splenectomy, and 3 patients with ABO-compatible LDLT with splenectomy were enrolled. The mortality of the 30 patients with HAI, without splenectomy, and with/without rituximab prophylaxis was 33% and the main cause of death was sepsis. Peripheral blood B cells were completely depleted, anti-donor blood-type antibody titer was lower, and clinical and pathological antibody-mediated rejection was not observed in patients with prophylaxis earlier than 7 days before transplantation (early prophylaxis). Early rituximab prophylaxis significantly depleted B cells and memory B cells in the spleen but not in lymph nodes. On the other hand, B cells and memory B cells increased and memory B cells became dominant during antibody-mediated rejection. In conclusion, early prophylaxis with rituximab depletes B cells, including memory B cells, in the spleen and is associated with a trend toward lower humoral rejection rates and lower peak immunoglobulin (Ig)G titers in ABO-I LDLT patients. Liver Transpl 13:579–588, 2007. © 2007 AASLD.
Developmental exposure to diethylstilbestrol alters uterine gene expression that may be associated with uterine neoplasia later in life
Authors: Newbold Retha R. , Jefferson Wendy N. , Grissom Sherry F. , Padilla‐Banks Elizabeth , Snyder Ryan J. , Lobenhofer Edward K.
Published: March 2007

Previously, we described a mouse model where the well‐known reproductive carcinogen with estrogenic activity, diethylstilbestrol (DES), caused uterine adenocarcinoma following neonatal treatment. Tumor incidence was dose‐dependent reaching >90% by 18 mo following neonatal treatment with 1000 µg/kg/d of DES. These tumors followed the initiation/promotion model of hormonal carcinogenesis with developmental exposure as initiator, and exposure to ovarian hormones at puberty as the promoter. To identify molecular pathways involved in DES‐initiation events, uterine gene expression profiles were examined in prepubertal mice exposed to DES (1, 10, or 1000 µg/kg/d) on days 1–5 and compared to controls. Of more than 20 000 transcripts, approximately 3% were differentially expressed in at least one DES treatment group compared to controls; some transcripts demonstrated dose–responsiveness. Assessment of gene ontology annotation revealed alterations in genes associated with cell growth, differentiation, and adhesion. When expression profiles were compared to published studies of uteri from 5‐d‐old DES‐treated mice, or adult mice treated with 17β estradiol, similarities were seen suggesting persistent differential expression of estrogen responsive genes following developmental DES exposure. Moreover, several altered genes were identified in human uterine adenocarcinomas. Four altered genes [lactotransferrin (Ltf), transforming growth factor beta inducible (Tgfb1), cyclin D1 (Ccnd1), and secreted frizzled‐related protein 4 (Sfrp4)], selected for real‐time RT‐PCR analysis, correlated well with the directionality of the microarray data. These data suggested altered gene expression profiles observed 2 wk after treatment ceased, were established at the time of developmental exposure and maybe related to the initiation events resulting in carcinogenesis. © 2007 Wiley‐Liss, Inc.
Striatal gray matter loss in Huntington's disease is leftward biased
Authors: Mühlau Mark , Gaser Christian , Wohlschläger Afra M. , Weindl Adolf , Städtler Michael , Valet Michael , Zimmer Claus , Kassubek Jan , Peinemann Alexander
Published: March 2007

In Huntington's disease (HD), the distribution of pathological changes throughout the brain is incompletely understood. Some studies have identified leftward‐biased lateralization, whereas others did not. We performed magnetic resonance imaging and a voxel‐based asymmetry analysis in 44 right‐handed HD gene carriers (presymptomatic, n = 5; stage I, n = 28; stage II, n = 11) and 44 right‐handed healthy controls. The group comparison revealed leftward‐biased gray matter loss in the striatum. Further analyses showed no indication of asymmetry in presymptomatic HD patients but an increase in asymmetry in the course of the HD stages under examination. Our study demonstrates and discusses leftward‐biased gray matter loss in HD. © 2007 Movement Disorder Society
Error estimates for sampling approximation of non‐bandlimited functions
Authors: Splettstößer W. , Törnig W.
Published: March 2007

A new proof of the sampling theorem for non‐bandlimited signals is presented. It leads to better rates of convergence for the envolved approximation process. Furthermore, the order of convergence is given for an extended class of functions.
Ein algebraisches Verfahren zur Lösung von gemischten Anfangsrandwertproblemen aus der Theorie instationärer Gitterströmungen
Authors: Meister E. , Sommer H. J.
Published: March 2007

Mixed boundary value problems for the wave‐equation in the x‐y‐plane, with boundaries parallel to the x‐axis, are usually treated by Laplacetransformation. To use this method numerically we present it here by means of the Mikusiński‐calculus. In this paper our main interest lies in the treatment of mixed initial‐boundary value problems arising in unsteady subsonic cascade flow.
Global existence for two‐velocity models of the Boltzmann equation
Authors: Illner R. , Neunzert H.
Published: March 2007

If A is a symmetric 2 × 2‐matrix,

equation image

then the initial value problem

equation image

describes the evolution in time of a fictive gas whose particles can move only with the velocities u1 and v2. It is proved that, for continuous initial values vanishing at infinity, (1) has a global solution if an H‐Theorem holds for the gas described by (1). The validity of an H‐Theorem is expressed by the properties of A.
Hopf‐Bifurkation bei Lasern
Authors: Renardy M. , Kirchgässner K.
Published: March 2007

The semiclassical equations describing a ring laser show two successive bifurcations, one stationary and one Hopf bifurcation. This phenomenon is analyzed mathematically. The initial value problem for the laser equations and the stability of the stationary solutions are discussed in detail. The transition to ultrashort laser pulses is shown to be a Hopf bifurcation. The direction of the bifurcation is determined for a numerical example. It turns out that it depends on the parameters of the system.
On the integral equation method for the plane mixed boundary value problem of the Laplacian
Authors: Wendland W. L. , Stephan E. , Hsiao G. C. , Meister E.
Published: March 2007

Although the plane boundary value problem for the Laplacian with given Dirichlet data on one part Γ2and given Neumann data on the remaining part Γ2of the boundary is the simplest case of mixed boundary value problems, we present several applications in classical mathematical physics. Using Green's formula the problem is converted into a system of Fredholm integral equations for the yet unknown values of the solutionuon Γ2and the also desired values of the normal derivatie on Γ1. One of these equations has principal part of the second kind, whereas that one of the other is of the first kind. Since any improvement of constructive methods requires higher regularity ofubut, on the other hand, gradupossesses singularities at the collision points Γ1∩ Γ2even forC∞data,uis decomposed into special singular terms and a regular rest. This is incorporated into the integral equations and the modified system is solved in appropriate Sobolev spaces. The solution of the system requires to solve a Fredholm equation of the first kind on the arc Γ2providing an improvement of regularity for the smooth part ofu. Since the integral equations form a strongly elliptic system of pseudodifferential operators, the Galerkin procedure converges. Using regular finite element functions on Γ1and Γ2augmented by the special singular functions we obtain optimal order of asymptotic convergence in the norm corresponding to the energy norm ofuand also superconvergence as well as high orders in smoother norms if the given data are smooth (and not the solution).
On boundary controllability of one‐dimensional vibrating systems
Authors: Krabs W. , Meister E.
Published: March 2007

In this paper boundary controllability of one‐dimensional vibrating system such as the vibrating string or the vibrating beam is studied. In particular we are concerned with the question whether it is possible to transfer a given initial state of vibration into rest within a given time such that the system stays in rest when the control is turned off.

This problem is rephrased as a typical trigonometric moment problem which is solved within the framework of an abstract moment problem in a Hilbert space. The results of null‐controllability which are obtained are substantially based on classical results of Ingham and Redheffer concerning trigonometric inequalities and incompleteness of certain sequences of trigonometric functions, respectively. The representation of the general statements follows closely the lines of a paper of Russell. Besides a special case is treated where explicit representations of boundary controls can be given that transfer the system to a permanent rest position. This special case includes amplitude boundary control of the vibrating string and the freely supported beam.
Stationary solutions of reaction‐diffusion equations
Authors: Hadeler K. P. , Rothe F. , Vogt H.
Published: March 2007

Given a semilinear reaction‐diffusion equation. If the corresponding ordinary differential equation admits a convex compact positively invariant set and the boundary data assume their values in this set then the first and third boundary value problem have stationary solutions. The proofs are based on Weinberger's strong invariance principle, some related tools and the Leray‐Schauder degree. The theorem is applied to several equations from theoretical biology, also in the case of distinct diffusion rates.
On a class of elliptic singular perturbations with applications in population genetics
Authors: Grasman J. , Eckhaus W.
Published: March 2007

With the maximum principle for differential equations asymptotic estimates are made for a class of linear elliptic singular perturbation problems with resonant turning point behaviour in some of the independent variables. The method is applied to the stationary solution of the Kolmogorov backward equation in population genetics.
The Crocco transformation for the three‐dimensional Prandtl boundary layer equations
Authors: Nickel K. , Kirchgässner K.
Published: March 2007

The three‐dimensional fluid flow of a steady or unsteady moving incompressible continuous medium is considered. Several Crocco‐type transformations are applied which reduce the system of three equations of the Prandtl boundary layer to a system of two strongly coupled parabolic equations.