bluuebunny/crossref_metadata_2025 huggingface dataset:
Hyperbranch‐polyethyleniminated functional polymers. I. Synthesis, characterization of novel ABA type of dumbbell‐like polyethyleniminated polyoxypropylenediamines, and their complexing properties with copper(II) ions in aqueous solution
Authors: Kuo Ping‐Lin , Liang Wuu‐Jyh , Wang Fu‐Yu
Published: March 2003

Novel ABA‐type dumbbell‐like water‐soluble copolymers [D230(EI)4, D400(EI)4, and D400(EI)8] were synthesized by introducing ethylenimine (EI) groups into both sides of polyoxypropylenediamines via a simple in situ ethylamination of polyoxypropylenediamine with 2‐chloroethylamine hydrochloride. The structures of the resultant polymers were identified by Fourier transform infrared spectroscopy and 1H NMR. The percentages of primary, secondary, and tertiary amine present were determined by the potentiometric titration method after treatments with the appropriate chemicals of salicylaldehyde and acetic anhydride. The surface tension and solubilizing behavior of pyrene in the presence of these polymers in aqueous medium were also investigated, and the efficiency to reduce the surface tension and solubilizing behavior of pyrene depends on the attachments of EI to polymer backbone. The chelating properties of these polymers were examined quantitatively by ultraviolet–visible (UV–vis) spectroscopy in the presence of Cu2+ ions in aqueous solution, and continuous variation analysis revealed that the most stable complex is formed at the normality ratio of [N]/[Cu2+] = 3.0. UV–vis spectroscopy and transmission electron microscopy were used to evaluate the dumbbell‐like water‐soluble copolymer, D400(EI)8, as a stabilizer for preparing colloidal noble metal nanoparticles (Au and Pt) in aqueous solution. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1360–1370, 2003
Latex particles bearing hydrophilic grafted hairs with controlled chain length and functionality synthesized by reversible addition–fragmentation chain transfer
Authors: D'Agosto Franck , Charreyre Marie‐Thérèse , Pichot Christian , Gilbert Robert G.
Published: March 2003

A method is described for synthesizing latex particles with anchored hairs by the grafting of hydrophilic chains, synthesized by reversible addition–fragmentation chain transfer, onto functionalized latex particles. These have the potential to bind biologically active species. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1188–1195, 2003
Synthesis, characterization, and mechanism studies on novel rare‐earth calixarene complexes initiating ring‐opening polymerization of 2,2‐dimethyltrimethylene carbonate
Authors: Ling Jun , Shen Zhiquan , Zhu Weipu
Published: March 2003

Rare‐earth (Nd, Y) p‐tert‐butylcalix[n]arene (n = 4, 6, and 8) complexes without coligands were synthesized from rare‐earth isopropoxides in toluene. The products were characterized as the following structures: [C4(OH)O3 · CH3C6H5]Nd (4), [C6(OH)2O4 · CH3C6H5]3Ln4 [Ln = Nd (5), Y (6)], and [C8(OH)2O6 · CH3C6H5]Nd2 (7). 2,2‐Dimethyl trimethylene carbonate (DTC) can be polymerized with complexes 4–7 alone as the initiator. PolyDTC (weight‐average molecular weight: 5700, polydispersity index: 1.11, measured by gel permeation chromatography) initiated by complex 5 was obtained with a conversion of 69.1% within 6 h in toluene at 80 °C. The thermal behavior of polyDTC has been compared with the published data. The DTC ring is opened via acyl‐oxygen bond cleavage with end‐group examination. NMR analyses of the polymerization reaction mixture indicated that the polymerization proceeds via a coordination‐insertion mechanism. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1390–1399, 2003
A Multi‐Electrode Approach for On‐Line Characterisation of Size and Shape
Authors: Zhang Yanmin , West Robert , Williams Richard A. , Spink Mark
Published: March 2003

A multi‐electrode approach is proposed for on‐line characterisation of particle size and shape in dilute particulate suspensions. Based on an electrozone principle, the approach uses four electrodes in a tube rather than two electrodes across an aperture employed in conventional methods. The outer two electrodes are used for current injection, while the inner two electrodes yield voltage measurement. A sensor designed in this way can reduce errors of false counts and oversizing that may occur in conventional methods, thus providing more accurate particle sizing. It is also possible to use the signal slope along with signal peak for particle size and shape characterisation. Both theoretical modelling and experiments were conducted, showing that particle aspect ratio along with particle diameter can be obtained, for example, for cylindrical particles.
Sex hormone‐induced alterations in the activities of antioxidant enzymes and lipid peroxidation status in the prostate of noble rats
Authors: N.C. Tam Neville , Ghatak Shibnath , Ho Shuk‐Mei
Published: March 2003

BACKGROUND

Oxidative stress has been implicated in prostate carcinogenesis. In the Noble rat model, treatment of rats with testosterone (T) plus 17β‐estradiol (E2) induced dysplasia and adenocarcinoma. Previous reports from us and other have indicated a linkage between steroid hormones and oxidative status in prostate cells in vivo and in vitro. Here, we provide further evidence that androgens and estrogens could induce a lobe‐specific shift of prooxidant–antioxidant balance and alterations in antioxidant enzyme activities, leading to oxidative stress in the rat prostate gland in vivo.

METHODS

Male Noble rats were subjected to single (T, E2, or diethylstilbestrol [DES] alone) or combined (T + E2 or T + DES) hormone treatments. Lipid peroxidation status and antioxidant enzyme activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione reductase (GR), glucose‐6‐phosphate dehydrogenase (G6PD) were assayed spectrophotometrically.

RESULTS

Treatment of rats with T did not alter lipid peroxidation in either the ventral prostate (VP) or the dorsolateral prostate (DLP). In contrast, exposure of rats to DES or E2 modestly elevated lipid peroxidation in rat VP or DLP, respectively. Of importance, T + DES and T + E2 treatments of rats induced marked increases in lipid peroxidation in the VP and the DLP, respectively. Antioxidant enzyme activities in the VP and DLP exhibited differential responses to sex hormone challenges. The activities of catalase, GPx, GR, and G6PD were mostly suppressed in either single or dual hormone‐treated DLP, whereas there is a general increase of GR and G6PD activities in the VP after hormonal exposures. The changes in T + DES‐treated VP were most dramatic with a marked activation of GPx (by one‐fold), GR (by one‐fold), and G6PD (by five‐fold).

CONCLUSION

The lobe‐specific differential responses of hormone‐induced oxidative stress and modulations of antioxidant enzymatic defenses in the rat prostate suggest that reactive oxygen species may play a role in hormone‐induced prostate carcinogenesis. Prostate 55:1–8, 2003. © 2003 Wiley‐Liss, Inc.
Loss of CD10 (neutral endopeptidase) is a frequent and early event in human prostate cancer
Authors: Freedland Stephen J. , Seligson David B. , Liu Alvin Y. , Pantuck Allan J. , Paik Sun H. , Horvath Steve , Wieder Jeffrey A. , Zisman Amnon , Nguyen David , Tso Cho‐Lea , Palotie Aarno V. , Belldegrun Arie S.
Published: March 2003

BACKGROUND

We hypothesized that the aggressive LNCaP‐derived androgen‐independent cell line, CL1, might differ from LNCaP in their repertoire of cell surface markers and that these differences might typify changes that occur during clinical prostate cancer progression.

METHODS

The cell surface marker expression profiles of CL1 and LNCaP were examined using flow cytometry. Markedly differential gene expression was confirmed using RT‐PCR and further examined using immunohistochemistry among the prostate cancer cell lines LAPC‐4, LNCaP, CL1, CL2, DU145, and PC‐3. The expression of the most markedly differentially expressed surface marker, CD10, was further explored in a tissue microarray containing radical prostatectomy samples from 219 hormone naïve prostate cancer patients.

RESULTS

There were marked differences in the expression of CD10, CD13, CD26, CD33, CD44, CD54, CD55, and CD104 between CL1 and LNCaP. Results from both the RT‐PCR and immunohistochemistry confirmed the differential expression and found that CD10 demonstrated a pattern of expression in hormone sensitive but not hormone refractory cell lines. When CD10 expression was examined in a tissue microarray, CD10 expression was below the 25th percentile of matched normal prostate tissue in 68% of prostate cancers, below the median expression of matched normal prostate tissue in 86% of cancers, and completely absent in 34% of cancers. Samples of prostatic intraepithelial neoplasia demonstrated CD10 expression that was intermediate between normal prostatic tissue and prostate cancer. Among prostate cancer patients, CD10 expression did not correlate with Gleason score, pathological stage, or biochemical recurrence following radical prostatectomy.

CONCLUSIONS

These findings demonstrate that loss or decreased expression of CD10 is an early and frequent event in human prostate cancer and implicates CD10 as a potential therapeutic target for early stage hormone sensitive prostate cancer. Prostate 55:71–80, 2003. © 2003 Wiley‐Liss, Inc.
Polarity of prostate specific membrane antigen, prostate stem cell antigen, and prostate specific antigen in prostate tissue and in a cultured epithelial cell line
Authors: Christiansen Jason J. , Rajasekaran Sigrid A. , Moy Peggy , Butch Anthony , Goodglick Lee , Gu Zhennan , Reiter Robert E. , Bander Neil H. , Rajasekaran Ayyappan K.
Published: March 2003

BACKGROUND

Madin‐Darby canine kidney (MDCK) cells are immortalized epithelial cells that have been used extensively as a model system to study intracellular molecular trafficking, polarized expression, and secretion of proteins in various epithelia. In order to determine if MDCK cells might serve as a model to study molecular events within prostate epithelial cells, we have evaluated the polarized distribution of three prostate restricted proteins, PSMA, PSCA, and PSA, in situ, and in MDCK cells.

METHODS

Using immunofluorescence, confocal microscopy, cell surface biotinylation, antibody internalization, and biochemical assays we evaluated surface expression and secretion of three prostate restricted proteins expressed in MDCK cells. We compared these patterns of expression to results observed within prostatic epithelium.

RESULTS

We demonstrate that PSMA is localized primarily to the apical plasma membrane in both the prostatic epithelium and transfected MDCK cells, whereas PSCA is expressed in a non‐polarized fashion. We also show that PSA is secreted predominantly from the apical surface of transfected MDCK cells, consistent with in vivo observations.

CONCLUSIONS

Similar patterns of localization among MDCK and prostatic epithelial cells suggest that the mechanisms of polarized sorting within these cell types are conserved. Thus, MDCK cells offer a useful model system to study mechanisms of targeting of these proteins within the prostate. Prostate 55:9–19, 2003. © 2003 Wiley‐Liss, Inc.
Cellular senescence in the pathogenesis of benign prostatic hyperplasia
Authors: Castro Patricia , Giri Dipak , Lamb Dolores , Ittmann Michael
Published: March 2003

BACKGROUND

Senescent cells accumulate in tissues with age and show changes in protein expression that may influence the function of adjacent cells and contribute to the development of tissue pathologies associated with aging. Benign prostatic hyperplasia (BPH) is an extremely common disease of older men characterized by increased growth of prostatic epithelial and stromal cells. In BPH, there is an increased expression of Il‐1α by prostatic epithelial cells that results in elevated expression of FGF7 by stromal cells, which in turn is strongly correlated with epithelial proliferation.

METHODS

Human BPH tissue and primary cultures of prostatic epithelial cells were analyzed by histochemical and quantitative assays for senescence‐associated β galactosidase (SA‐β gal). Il‐1α expression was localized by immunohistochemistry and Il‐1α tissue content determined by enzyme‐linked immunoabsorption assay.

RESULTS

Expression of Il‐1α is significantly increased in vitro when cultured prostatic epithelial cells undergo senescence. In BPH tissue a substantial population of epithelial cells express senescence‐associated β galactosidase (SA‐β gal), a marker of cellular senescence. By quantitative assay, SA‐β gal activity is correlated with both tissue levels of Il‐1α and the severity of BPH.

CONCLUSIONS

One mechanism driving BPH in older men is the accumulation of senescent epithelial cells expressing Il‐1α, which in turn increases FGF7 secretion and proliferation of non‐senescent epithelial cells. Thus there is a mechanistic linkage between cellular senescence and one of the most common pathologies of older men. Prostate 55:30–38, 2003. © 2003 Wiley‐Liss, Inc.
Laminin alpha‐1, alpha‐3, and alpha‐5 chain expression in human prepubetal benign prostate glands and adult benign and malignant prostate glands
Authors: Brar Preetinder K. , Dalkin Bruce L. , Weyer Chris , Sallam Karim , Virtanen Ismo , Nagle Raymond B.
Published: March 2003

BACKGROUND

Laminins (Lns) are a family of extracellular matrix glycoproteins located in the basement membrane (BM) of epithelial cells. They exist as heterotrimers composed of an α, β, and γ chain. Presently, five α (α1–5), three β (β1–3), and three γ (γ1–3) chains have been identified with different combinations of these chains resulting in 14 laminin heterotrimers thus far identified (1, 3–5).

METHODS

In this study, using immunohistochemistry with chain‐specific antibodies, we characterized the expression of the α1 (Lns‐1/3), α3 (Lns 5,6,7), and α5 (Lns 10/11) chains in fetal, newborn, infant, prepubertal, and adult benign and malignant prostate glands.

RESULTS

In general, α1 expression was higher in normal fetal prostate glands and declined by full‐term birth, whereas the α3 and α5 chains remained highly expressed in the adult normal glands. In carcinoma α1 (Lns 1/3) and α5 (Lns 5,6,7) are lost, whereas α5 (Lns 10/11) persists.

CONCLUSIONS

Alpha 1 (Lns 1/3) is prominent in BM, but is replaced by a laminin matrix rich in α3 (Lns 5,6,7) and α5 (Lns 10/11) in benign adult prostate glands. In carcinoma, both α1 (Lns‐1/3) and α3 (Lns 5,6,7) are not expressed with persistence of a BM rich in α5 (Lns 10/11). Prostate 55:65–70, 2003. © 2003 Wiley‐Liss, Inc.
MicroPET imaging of prostate cancer in LNCAP‐SR39TK‐GFP mouse xenografts
Authors: Yang Honghao , Berger Frank , Tran Chris , Gambhir Sanjiv S. , Sawyers Charles L.
Published: March 2003

BACKGROUND

The aim of this study was to develop models that allow serial, noninvasive imaging of human prostate cancer cells in immunodeficient mice using a dedicated small animal positron emission tomography scanner (microPET).

METHODS

LNCaP tumor cells were stably transduced ex‐vivo with the mutant herpes simplex virus type 1 thymidine kinase (HSV‐sr39tk) PET reporter gene and green fluorescent protein (GFP). The stably transduced LNCaP cells were then enriched via fluorescent cell sorting and implanted into SCID mice. Beginning 2 weeks after tumor cell inoculation, mice were repeatedly scanned by microPET performed 1 hr after tail‐vein injection of ∼200 μCi Fluorine‐18 labeled penciclovir (18F‐FHBG). PET‐images were correlated to tumor size, % injected dose (ID)/g tumor tissue, PSA levels, autoradiography, and histology.

RESULTS

Monitoring LNCaP xenografts using microPET and our reporter gene approaches is feasible. MicroPET was capable of detecting subcutaneous tumors as small as 3 mm in diameter (∼0.2% ID/g). The magnitude of 18F‐FHBG‐uptake in PET‐images correlated with the tumor volumes and the serum PSA levels. Other non‐HSV1‐TK‐specific tracers were also studied. While 18F‐flurodeoxyglucose (18F‐FDG) gave poor imaging results in LNCaP cells, 11C‐acetate gave satisfactory images.

CONCLUSIONS

We demonstrated the feasibility of monitoring prostate cancer xenografts in a mouse model using microPET and the HSV1‐sr39tk PET reporter gene/18F‐FHBG reporter probe system. Extension of this approach may allow repetitive imaging of tumor metastases. Prostate 55:39–47, 2003. © 2003 Wiley‐Liss, Inc.
Tissue microarray analysis reveals prognostic significance of syndecan‐1 expression in prostate cancer
Authors: Zellweger Tobias , Ninck Christoph , Mirlacher Martina , Annefeld Matthias , Glass Andrew G. , Gasser Thomas C. , Mihatsch Michael J. , Gelmann Edward P. , Bubendorf Lukas
Published: March 2003

BACKGROUND

Tissue microarrays (TMA) have recently emerged as powerful tools to rapidly analyze the clinical significance of new molecular markers in human tumors. Here, we have tested several molecular markers on a prostate TMA containing 637 different specimens.

METHODS

The specimens were from 551 patients with prostate cancer and long‐term follow‐up information on progression (median 5.3 years), tumor‐specific and overall survival (median 5.9 years). Eighty‐six specimens from benign prostatic hyperplasia were included as controls. Expression of Ki67, Bcl‐2, p53, CD‐10 (neutral endopeptidase), and syndecan‐1 (CD‐138) was analyzed by immunohistochemistry.

RESULTS

Gleason grade and Ki67 Labeling Index (LI) were independent predictors of early recurrence and poor survival. Bcl‐2 predicted early recurrence, whereas p53 was associated with poor survival. Syndecan‐1 overexpression also predicted early recurrence and was significantly associated with tumor specific survival, high Gleason grade, Ki67 LI, and Bcl‐2 overexpression. Neoadjuvant hormonal therapy was associated with overexpression of Bcl‐2 and inhibition of Ki67 LI and CD‐10, but did not affect the expression of the remaining markers.

CONCLUSIONS

The results of this TMA study confirm a dominant prognostic significance of Gleason grading and Ki67 LI in prostate cancer, as compared to a less pronounced role of Bcl‐2, and p53. We identified syndecan‐1 as a new prognostic factor and provide evidence for an androgen‐dependent regulation of CD‐10 expression. Prostate 55:20–29, 2003. © 2003 Wiley‐Liss, Inc.
Biochemical recurrence following radical prostatectomy: A comparison between prostate cancers located in different anatomical zones
Authors: Augustin Herbert , Erbersdobler Andreas , Graefen Markus , Fernandez Salvador , Palisaar Jüri , Huland Hartwig , Hammerer Peter
Published: March 2003

BACKGROUND

To assess whether differences of biochemical recurrence after radical prostatectomy exist between prostate cancers located in the transition zone (TZ) and peripheral zone (PZ).

METHODS

The 5‐year biochemical recurrence rate of 307 patients was evaluated. A serum prostate specific antigen (PSA) level ≥0.1 ng/ml was defined as biochemical failure. Cancers were characterized by the location of the largest tumor area as TZ or PZ cancers. Pure PZ cancers were matched to TZ cancers by comparable pathological tumor stage, Gleason score, and surgical margin status.

RESULTS

In 63 (20.5%) patients the largest tumor area was located in the TZ. A Kaplan–Meier analysis of the matched pairs calculated an 80% actuarial cure rate of TZ cancers compared to 89% of pure PZ cancers (log‐rank test P = 0.742).

CONCLUSIONS

TZ and pure PZ cancers matched by comparable pathological tumor stage, Gleason score, and surgical margin status showed no statistical difference in regard to biochemical cure following radical prostatectomy. Prostate 55:48–54, 2003. © 2003 Wiley‐Liss, Inc.
Molecular characterization of prostatic small‐cell neuroendocrine carcinoma
Authors: Clegg Nigel , Ferguson Camari , True Lawrence D. , Arnold Hugh , Moorman Alec , Quinn Janna E. , Vessella Robert L. , Nelson Peter S.
Published: March 2003

OBJECTIVES

A subset of prostate carcinomas is composed predominantly, even exclusively, of neuroendocrine (NE) cells. In this report, we sought to characterize the gene expression profile of a prostate small cell NE carcinoma by assessing the diversity and abundance of transcripts in the LuCaP 49 prostate small cell carcinoma xenograft.

METHODS

We constructed a cDNA library (PRCA3) from the LuCap 49 prostate small cell xenograft. Single pass DNA sequencing of randomly selected cDNA clones followed by sequence assembly and annotation produced a library of Expressed Sequence Tags (ESTs) representing the LuCaP 49 transcriptome. Comparative sequence analysis with ESTs derived from prostate adenocarcinoma libraries was performed using statistical algorithms designed to identify differentially expressed sequences. Putative NE cell‐specific genes were further examined by Northern analysis.

RESULTS

Sequence assembly and analysis identified 1,447 distinct genes expressed in the LuCaP 49 cDNA library. These include cDNAs encoding the NE markers secretogranin (SCG2), CD24, and ENO2. Northern analysis revealed that three additional genes, ASCL1, INA, and SV2B are expressed in LuCaP 49 but not in various prostate cancer cell lines or xenografts. Fifteen genes were identified with a statistical probability (P > 0.9) of being up‐regulated in LuCaP 49 small cell carcinoma relative to prostate adenocarcinoma (two primary prostate adenocarcinomas and the LNCaP prostate adenocarcinoma cell line).

CONCLUSIONS

Prostate small cell carcinoma expresses a diverse repertoire of genes that reflect characteristics of their NE cell of origin. ASCL1, INA, and SV2B are potential molecular markers for small cell NE tumors and NE cells of the prostate. This small cell NE carcinoma gene expression profile may yield insights into the development, progression, and treatment of subtypes of prostate cancer. Prostate 55:55–64, 2003. © 2003 Wiley‐Liss, Inc.
Dynamic control of a SI engine with variable intake valve timing
Authors: Kang Jun‐Mo , Grizzle J.W.
Published: March 2003

Engines equipped with a means to actuate air flow at the intake valve can achieve superior fuel economy performance in steady state. This paper shows how modern nonlinear design techniques can be used to control such an engine over a wide range of dynamic conditions. The problem is challenging due to the nonlinearities and delays inherent in the engine model, and the constraint on the air flow actuator. The controller is designed on the basis of a mean‐value model, which is derived from a detailed intake stroke model. The control solution has two novel features. Firstly, a recovery scheme for integrator wind‐up due to input constraints is directly integrated into the nonlinear control design. The second novel feature is that the control Lyapunov function methodology is applied to a discrete‐time model. The performance of the controller is evaluated and compared with a conventionally controlled engine through simulation on the detailed engine model. Copyright © 2003 John Wiley & Sons, Ltd.
Current‐mode control of DC–DC power converters: a backstepping approach
Authors: Alvarez‐Ramirez J. , Espinosa‐Pérez G. , Noriega‐Pineda D.
Published: March 2003

Current‐mode control is a robust industrial DC–DC power converter control scheme that has been successfully tested, is widely accepted, and is commonly implemented with conventional linear P and PI controllers. The need of more systematic designs with enhanced performance has motivated recent studies with linear and nonlinear advanced techniques, but the rigorous understanding and substantiation of the underlying key robust functioning capability are still lacking. In this paper, a constructive control approach is employed to study the current‐mode control problem of a class of DC–DC power converters, yielding a cascade control design methodology with: a robust convergence criterion coupled with a systematic and transparent construction‐tuning procedure, a rationale to explain the robust controller functioning, and a unified framework to interpret and compare the proposed controller with the existing conventional and advanced control designs. The implementation and functioning of the proposed control design is illustrated experimentally with a boost converter. Copyright © 2003 John Wiley & Sons, Ltd.
Sliding mode observers for robust detection and reconstruction of actuator and sensor faults
Authors: Tan Chee Pin , Edwards Christopher
Published: March 2003

This paper describes a method for designing sliding mode observers for detection and reconstruction of actuator and sensor faults, that is robust against system uncertainty. The method uses ℋ︁∞concepts to design the sliding motion so that an upper bound on the effect of the uncertainty on the reconstruction of the faults will be minimized. The design method is first applied to the case of actuator faults, and then by some appropriate filtering, the method is extended to the case of sensor faults. A VTOL aircraft example taken from the fault detection literature is used to demonstrate the method and its effectiveness. Copyright © 2003 John Wiley & Sons, Ltd.
Stability analysis and guaranteed domain of attraction for a class of hybrid systems: an LMI approach
Authors: Bean S. Palomino , Coutinho D.F. , Trofino A. , Cury J.E. R.
Published: March 2003

This paper presents sufficient conditions for the regional stability problem for switched piecewise affine systems, a special class of Hybrid Systems. This class of systems are described by an affine differential equation of the type x˙=A(δ)x+b(δ), where x denotes the continuous state vector and δ is a vector of logical variables that modifies the local model of the system in accordance with the continuous dynamics. Using a Lyapunov function of the type v(x)=x′P(x)x, we present LMI conditions that, when feasible, guarantee local stability of the origin of the switched system. Examples of switched affine systems are used to illustrate the results. Copyright © 2003 John Wiley & Sons, Ltd.
Stabilization of a solid propellant rocket instability by state feedback
Authors: Bošković Dejan M. , Krstić Miroslav
Published: March 2003

In this paper a globally stabilizing feedback boundary control law for an arbitrarily fine discretization of a one‐dimensional nonlinear PDE model of unstable burning in solid propellant rockets is presented. The PDE has a destabilizing boundary condition imposed on one part of the boundary. We discretize the original nonlinear PDE model in space using finite difference approximation and get a high order system of coupled nonlinear ODEs. Then, using backstepping design for parabolic PDEs, properly modified to accommodate the imposed destabilizing nonlinear boundary condition at the burning end, we transform the original system into a target system that is asymptotically stable in l2‐norm with the same type of boundary condition at the burning end, and homogeneous Dirichlet boundary condition at the control end. Copyright © 2003 John Wiley & Sons, Ltd.
Virtual object overlay onto uncalibrated camera images for augmented reality
Authors: Harasaki Shunsuke , Saito Hideo
Published: March 2003

We propose a new registration algorithm for overlaying a virtual object generated in a graphics system onto a real‐world image sequence captured by an uncalibrated camera for augmented reality. In our method, a Projective Grid Space (PGS) is defined by using two base images captured from different positions with uncalibrated cameras. In the PGS, correct perspective views of a virtual object can be registered onto an image sequence captured by an uncalibrated camera in real time. Since our method is based on the projective geometry that is defined by two base images, the registration does not require any markers with known 3D positions, but several (at least eight) image feature points are needed for estimating fundamental matrices of the augmented camera with the base images. Based on this method, we constructed an augmented reality system for an uncalibrated camera without any 3D position information in the real world, which runs nearly at video rate (11 frames per second). Experimental results demonstrate the advantages of this method. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 47–55, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10261
Development of extraction method of kidneys from abdominal CT images using a three‐dimensional deformable model
Authors: Tsagaan Baigalmaa , Shimizu Akinobu , Kobatake Hidefumi , Miyakawa Kunihisa
Published: March 2003

This paper presents a method of extraction of kidneys from abdominal CT images using a three‐dimensional deformable model. In the proposed method, an initial surface model is located in an appropriate position of the image and deformed to fit the target's boundaries. Shape feature is incorporated into the deformable model through energy function as a priori knowledge of the target. Concretely, principal curvatures of the model surface are adopted to characterize the geometrical features of the target and its mean and covariance with the neighboring shape are considered when the deformation is demonstrated. We have applied the proposed method to extract kidneys from three‐dimensional abdominal CT images. The experimental results are presented and the effectiveness of the method is discussed in this paper. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 25–36, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10268
A method of multichannel PID control of two‐degree‐of‐freedom wrist joint movements by functional electrical stimulation
Authors: Watanabe Takashi , Iibuchi Kan , Kurosawa Kenji , Hoshimiya Nozomu
Published: March 2003

In restoring motor functions of paralyzed extremities by functional electrical stimulation (FES), determination of stimulus intensities of many muscles in multichannel control is an ill‐posed problem because of redundancy in the input (stimulus intensity)‐output (joint angle) relationship of the musculoskeletal system. In this paper, we use a multi‐input and multi‐output PID controller and propose a parameter determination method for the controller, which can solve the ill‐posed problem in closed‐loop control. In the parameter determination process, the stimulus intensity‐joint angle characteristics of all muscles controlled were measured first. The elements of the matrix that transforms stimulus intensities into joint angles were determined by linear approximation of the measured characteristics. Then a generalized inverse matrix of the transformation matrix was calculated. The generalized inverse matrix and an expanded CHR method were used to determine the parameters of the PID controller. The PID controller was examined in tracking control on several trajectories of two‐degree‐of‐freedom movement of the wrist joint with neurologically intact subjects. Electrical stimulation was applied to four muscles relating to the wrist joint movements through surface electrodes. The tracking control was achieved generally with good performance under different conditions of the gravitational effect. The new method proposed in this paper was found to provide a solution of the ill‐posed problem. Multichannel closed‐loop FES control of the wrist joint could be realized with this method. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 25–36, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10298
Required quantizing resolution for perceptually linearized medical x‐ray images on display monitor
Authors: Furukawa Isao , Suzuki Junji , Ono Sadayasu
Published: March 2003

This paper theoretically clarifies required quantizing resolution to display digitized x‐ray images on a cathode‐ray‐tube (CRT) monitor provided that the observer not recognize contours that do not exist in original x‐ray film images. Human visual system for luminance difference discrimination is an important factor in determining required quantizing resolution. We therefore carry out an analysis using the Barten model, which provides good fit of many experimental data. First, we clarify the required quantizing resolution for the density input to film and that for the voltage input to a CRT monitor. Then, we present the design results of the look‐up table for perceptually linear transform for a CRT that can reproduce the luminance difference information in film images, and clarify the validity of our theoretical studies. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 14–24, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10301
A line drawing simplification method which retains shape by using the fractal dimension
Authors: Uemura Satoshi , Haseyama Miki , Kitajima Hideo
Published: March 2003

This paper presents a novel method for simplification of line drawings which can retain the shape of a given object. By noting that natural shapes innately possess the property designated self‐similarity, the fractal dimension, one of the characteristics of fractal objects and a measure of complexity, is used as an index. With this index the degree of simplification can be quantified. In order to represent the approximation of a given object, the feature points are extracted by our analysis, whose basic idea was derived from Vector Tracer. Experimental results show the efficiency of our proposed method. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 1–13, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10317
Memory‐based self‐localization using omnidirectional images
Authors: Iwasa Hidehiko , Aihara Nobuhiro , Yokoya Naokazu , Takemura Haruo
Published: March 2003

For a robot, recognizing its location in a real environment is important in terms of visual navigation, etc. This paper proposes a memory‐based self‐localization method based on the use of omnidirectional images. In the proposed method, information that is constant relative to rotation around the axis of an omnidirectional image sensor is first extracted by generating autocorrelation images from omnidirectional images containing global information that is useful for self‐localization. Next, eigenspaces are formed from the generated autocorrelation images, and self‐localization is performed by searching for the learning images that are closest to the input image in the eigenspace. Additionally, performing self‐localization in two stages (general and local) results in robust self‐localization. Lastly, experiments were conducted using time‐series omnidirectional images that were actually captured both indoors and outdoors to verify the effectiveness of the proposed method. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 56–68, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1203
Multiple beamforming with source localization based on CSP analysis
Authors: Nishiura Takanobu , Nishioka Ryousuke , Yamada Takeshi , Nakamura Satoshi , Shikano Kiyohiro
Published: March 2003

In this paper, a method is investigated for using an array of microphones to capture a high‐quality recording of voice under reverberation. In the past, multiple beamforming has been proposed by Flanagan's group as a method for efficiently suppressing reverberation. However, because this multiple beamforming method computes the arrival positions of the sound and its reflections based on the prior knowledge of the shape of the room and the position of the target sound source, it is not suited to practical applications. In this paper, a method of multiple beamforming is proposed in which the source positions of the sound and its reflections are localized without using prior knowledge of the shape of the room or the position of the target sound source. The effectiveness of the proposed method was evaluated in a simulation experiment using the image method and in an experiment in an actual hallway environment. First, an experiment was run to localize the positions of the sources of the sound and its reflections under a condition in which both the shape of the room and the source position of the sound were unknown. As the result, it was found that the localization error for the source position of the sound was small. Furthermore, although the localization errors for the source positions of the reflections were large, the localized reflection paths were found to be approximately equal to the true reflection paths. Next, the output signal from the proposed method was evaluated based on SNR. The result demonstrated that multiple beamforming is more effective than single beamforming. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 69–80, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1204
Ranking of documents by measures considering conceptual dependence between terms
Authors: Nakashima Makoto , Kaneko Yuichi , Ito Tetsuro
Published: March 2003

There is demand for a retrieval system that would support extraction of documents even without recognizing new query expressions, while offering a user interface featuring an easy way to evaluate relevance of search results. In this paper, a solution to such a need is offered. Topics of queries and documents are normally represented by search terms. Thus, terms are assumed to be associated through a concept hierarchy; measures are found that reflect, in a natural way, conceptual relations between terms through associativity between a query and a document; a method is developed to rank documents using such measures. These measures consider specificity of coverings of expressions mentioned in both the query and the document with regard for concept hierarchy. Experiments confirmed that the proposed measures were helpful in evaluating conceptual associativity, while document ranking based on these measures proved more efficient compared to traditional similarity measures. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(5): 81–91, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1205
Proactive environmental strategies: a stakeholder management perspective
Authors: Buysse Kristel , Verbeke Alain
Published: March 2003

This paper includes an empirical analysis of the linkages between environmental strategy and stakeholder management. First, it is shown that several simultaneous improvements in various resource domains are required for firms to shift to an empirically significant, higher level of proactiveness. Second, more proactive environmental strategies are associated with a deeper and broader coverage of stakeholders. Third, environmental leadership is not associated with a rising importance of environmental regulations, thereby suggesting a role for voluntary cooperation between firms and government. Finally, the linkages between environmental strategies and stakeholder management, based on a sample of 197 firms operating in Belgium, appear more limited than expected. Country‐specific characteristics may to a large extent account for these results. Copyright © 2002 John Wiley & Sons, Ltd.
Environmental dynamism and strategic decision‐making rationality: an examination at the decision level
Authors: Hough Jill R. , White Margaret A.
Published: March 2003

Several approaches have been used to explore environmental dynamism as a contingent predictor of the relationship between rational‐comprehensive strategic decision‐making and firm‐level performance. At the decision level of analysis, however, small sample sizes, low statistical power, and statistical dependence have plagued the research. Through the use of a simulated decision‐making environment and multilevel analysis, this study examined 400 decisions from 54 executive teams. Consistent with much of the existing firm‐level research, the results indicated that environmental dynamism may moderate the relationship between rational‐comprehensive decision making and decision quality. Surprisingly, the form of the relationship differed from much of the firm‐level research. Copyright © 2003 John Wiley & Sons, Ltd.
QoS customization in distributed object systems
Authors: He Jun , Hiltunen Matti A. , Rajagopalan Mohan , Schlichting Richard D.
Published: March 2003

Applications built on networked collections of computers are increasingly using distributed object platforms such as CORBA,Java Remote Method Invocation (RMI), and DCOM to standardize object interactions. With this increased use comes the increased need for enhanced quality of service (QoS) attributes related to fault tolerance, security, and timeliness. This paper describes an architecture called CQoS (configurable QoS) for implementing such enhancements in a transparent, highly customizable, and portable manner. CQoS consists of two parts: application‐ and platform‐dependent interceptors and generic QoS components. The generic QoS components are implemented using Cactus, a system for building highly configurable protocols and services in distributed systems. The CQoS architecture and the interfaces between the different components are described, together with implementations of QoS attributes using Cactus and interceptors for CORBA and Java RMI. Experimental results are given for a test application executing on a Linux cluster using Cactus/J, the Java implementation of Cactus. Compared with other approaches, CQoS emphasizes portability across different distributed object platforms, while the use of Cactus allows custom combinations of fault‐tolerance, security, and timeliness attributes to be realized on a per‐object basis in a straightforward way. Copyright © 2003 John Wiley & Sons, Ltd.
From pattern to process: identifying predator–prey models from time‐series data
Authors: Jost C. , Arditi R.
Published: March 2003

Fitting nonlinear models to time‐series is a technique of increasing importance in population ecology. In this article, we apply it to assess the importance of predator dependence in the predation process by comparing two alternative models of equal complexity (one with and one without predator dependence) to predator–prey time‐series. Stochasticities in such data come from both observation error and process error. We consider how these errors must be taken into account in the fitting process, and we develop eight different model selection criteria. Applying these criteria to laboratory data on simple protozoan and arthropod predator–prey systems shows that little predator dependence is present, with one interesting exception. Field data are more ambiguous (either selection depends on the particular criterion or no significant differences can be detected), and we show that both models fit reasonably well. We conclude that, within our modeling framework, predator dependence is in general insignificant in simple systems in homogeneous environments. Relatively complex systems show significant predator dependence more often than simple ones but the data are also often inconclusive. The analysis of such systems should rely on several models to detect predictions that are sensitive to predator dependence and to direct further research if necessary.
THE TREE CUT AND MERGE ALGORITHM FOR ESTIMATION OF NETWORK
RELIABILITY
Authors: Hui K.-P. , Bean N. , Kraetzl M. , Kroese D.
Published: April 2003

This article presents Monte Carlo techniques for estimating
network reliability. For highly reliable networks, techniques
based on graph evolution models provide very good performance.
However, they are known to have significant simulation cost.
An existing hybrid scheme (based on partitioning the time space)
is available to speed up the simulations; however, there are
difficulties with optimizing the important parameter associated
with this scheme. To overcome these difficulties, a new hybrid
scheme (based on partitioning the edge set) is proposed in this
article. The proposed scheme shows orders of magnitude improvement
of performance over the existing techniques in certain classes
of network. It also provides reliability bounds with little
overhead.
On‐Line Optimization of Recombinant Product in a Fed‐Batch Bioreactor
Authors: Mahadevan Radhakrishnan , III Francis J. Doyle
Published: April 2003

In this paper, an efficient scheme for on‐line optimization of a recombinant product in a fed‐batch bioreactor is presented. This scheme is based on the parametrization of the system states and the elimination of a subset of the dynamic equations in the mathematical model of the fed‐batch bioreactor. The fed‐batch bioreactor considered here involves the production of chloramphenicol acetyltransferase (CAT) in a genetically modified E. coli. The optimal inducer and the glucose feed rates are obtained using the proposed optimization approach. This approach is compared with the traditional optimization approach, where all the states and the manipulated variables are parametrized. The approach presented in this paper results in a 5‐fold improvement in the computational time for the recombinant product optimization. The optimization technique is employed in an on‐line optimization scheme, when parametric drift and a disturbance in the manipulated variable is present. Feedback from the process is introduced through resetting the initial conditions of the model and through an observer for estimating the time varying parameter. The simulation results indicated improvement in the amount of product formed, when the optimal profile is regenerated during the course of the batch.
Evolution of Culture Broth Rheological Properties during Propagation of the Entomopathogenic Nematode Steinernemacarpocapsae, in Submerged Monoxenic Culture
Authors: Chavarría‐Hernández Norberto , Inés Rodríguez‐Hernández Adriana , Pérez‐Guevara Fermín , Torre Mayra de la
Published: April 2003

This article presents the evolution of culture broth rheological properties during monoxenic cultures of Steinernema carpocapsaein cylindrical bottles agitated orbitally. Rheological properties were evaluated in simple‐shear flow conditions and were well‐modeled by the Ostwald‐de Waele model. Rheological properties varied from slightly dilatant, n= 1.2 (–), to moderately pseudoplastic flow behavior, n= 0.6 (–). Nematode concentrations increased from 750 ± 190 to 130 900 ± 6900 nematodes/mL, and the apparent viscosity (ηa) evolved from 4.5 ± 0.7 to 46.6 ± 3.2 mPa·s during the fermentations. Rheological behavior did not appear to be strongly influenced by nematode number and/or its stage of development; however, the release of substances from the decomposition of nematode cadavers appeared to be of great importance. Among the different developmental stages of the nematodes, only juveniles of the first stage (J1) were highly susceptible to the shearing conditions tested (shear stress, θrθ, from 0.9 to 3.5 Pa during periods of 80–100 min), resulting in the viability loss of 85% of J1 nematodes.
Sociopolitical Development as an Antidote for Oppression—Theory and Action
Authors: Watts Roderick J. , Griffith Derek M. , Abdul-Adil Jaleel
Published: April 2003

Although psychology has an ample vocabulary for describing individual pathologies, the development of theory and concepts for understanding societal pathology remains in its infancy. Because community psychology theory views human behavior in its context, it is essential that interventions not be limited to stress management, personal coping, and similar programming. Interventions should not leave social injustice undiscussed and unchallenged. In this spirit we present a theory of oppression and sociopolitical development that informs an intervention with young, African American men in an urban setting. The five‐stage theory highlights the role of Freire's notion of “critical consciousness,” a sociopolitical version of critical thinking, in enhancing an awareness of sociopolitical as well as personal forces that influence behavior. The theory also draws on African American social‐change traditions and their spiritual aspects. The action section of the study describes the Young Warriors program's use of mass culture (rap videos and film) as stimuli for the development of critical consciousness. Highlights from an empirical investigation of an eight‐session high school version of the program will be presented to illustrate the practical challenges and benefits of sociopolitical interventions.