bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of hepatocellular carcinoma by ferumoxides‐enhanced MR imaging in cirrhosis: Incremental value of dynamic gadolinium‐enhancement
Authors: Qayyum Aliya , Thoeni Ruedi F. , Coakley Fergus V. , Lu Ying , Guay Jeff P. , Ferrell Linda D.
Published: November 2005

Purpose:

To investigate the incremental value of dynamic gadolinium‐enhancement performed immediately after ferumoxides‐enhanced magnetic resonance (MR) imaging on the detection of hepatocellular carcinoma in patients with cirrhosis.

Materials and Methods:

We retrospectively reviewed MR scans of 62 cirrhotic patients over a two‐year period. Sequences included ferumoxides‐enhanced T2‐weighted fast spin echo followed by dynamic gadolinium‐enhanced T1‐weighted spoiled gradient echo. Two readers independently documented the presence of hepatocellular carcinoma on a three‐point confidence scale, without and with gadolinium‐enhanced images. The presence or absence of hepatocellular carcinoma was established by histopathology (58 patients) or follow‐up imaging (four patients) over a mean period of nine months.

Results:

A total of 71 hepatocellular carcinomas were found in 42 patients. There was no statistically significant difference in sensitivity for the diagnosis of hepatocellular carcinoma without vs. with gadolinium‐enhanced images (68% vs. 74% for reader 1 and 62% vs. 73% for reader 2, respectively, P > 1.3). However, both readers showed a lower mean confidence for tumor detection without vs. with gadolinium‐enhanced images (2.3 vs. 2.7 for reader 1, 2.3 vs. 2.9 for reader 2, P < 0.01).

Conclusion:

In our study, the addition of dynamic gadolinium‐enhancement to ferumoxides‐enhanced MR imaging did not improve hepatocellular carcinoma detection, but the addition of gadolinium‐enhancement is recommended if ferumoxides‐enhanced imaging is used because it increased reader confidence. J. Magn. Reson. Imaging 2006. © 2005 Wiley‐Liss, Inc.
Effect of different levels of CO2 on the antioxidant content and the polyphenol oxidase activity of ‘Rocha’ pears during cold storage
Authors: Galvis‐Sánchez Andrea C , Fonseca Susana C , Gil‐Izquierdo Ángel , Gil María I , Xavier Malcata F
Published: November 2005

Pears (Pyrus communis L. cv. ‘Rocha’) were exposed to air or controlled atmosphere (CA) containing various concentrations of CO2: 0, 0.5 and 5 kPa, all with 2 kPa O2. After 4 months of storage at 2 °C, the fruits were transferred to air at room temperature, and assessed in terms of soluble solids, titratable acidity, pH, incidence of brown heart and flesh browning, phenolic content, vitamin C content and polyphenol oxidase activity. By 4 months of storage, soluble solids and pH increased, and acidity decreased relative to harvest, but no differences were detected between pears stored under air or any of the CA tested. Higher contents of hydroxycinnamic derivatives and flavan‐3‐ols in the peel than in the flesh were recorded. However, the content of arbutin was higher in the flesh than in the peel, whereas flavonols were only detected in the peel. In general, hydroxycinnamic derivatives and flavonols were stable throughout storage, but flavan‐3‐ols decreased in concentration under air or CA. Arbutin was the only phenolic compound that increased in concentration as time elapsed. No clear relation was found between the storage conditions tested and the phenolic concentration in pears. Regarding ascorbic acid (AA) and dehydroascorbic acid (DHA), their concentrations were higher in the peel than in the flesh. Furthermore, AA and DHA were strongly affected by storage: the former decreased, whereas the latter increased in content. A decrease in PPO activity was apparent after harvest and during storage, particularly under higher levels of CO2. The combination 2 kPa O2 + 5 kPa CO2 increased the incidence of internal disorders (viz. brown heart and flesh browning) after storage. Copyright © 2005 Society of Chemical Industry
The effect of HLA mismatches, shared cross-reactive antigen groups, and shared HLA-DR antigens on the outcome after pediatric liver transplantation
Authors: Sieders Egbert , Hepkema Bouke G. , Peeters Paul M.J.G. , TenVergert Elisabeth M. , de Jong Koert P. , Porte Robert J. , Bijleveld Charles M.A. , van den Berg Aad P. , Lems Simon P.M. , Gouw Annette S.H. , Slooff Maarten J.H.
Published: November 2005

The aim of this study was to analyze the effect of human leukocyte antigen (HLA) class I and HLA-DR mismatching, sharing cross-reactive antigen groups (CREGs), and sharing HLA-DR antigens on the outcome after pediatric liver transplantation. Outcome parameters were graft survival, acute rejection, and portal fibrosis. A distinction was made between full-size (FSLTx) and technical-variant liver transplantation (TVLTx). A total of 136 primary transplants were analyzed. The effect of HLA on the outcome parameters was analyzed by adjusted multivariate logistic and Cox regression analysis. HLA mismatches, shared CREGs, and shared HLA-DR antigens affected neither overall graft survival nor survival after FSLTx. Survival after TVLTx was superior in case of 2 mismatches at the HLA-DR locus compared to 0 or 1 mismatch (

P

= 0.01) and in case of no shared HLA-DR antigen compared to 1 shared HLA-DR antigen (

P

= 0.004). The incidence of acute rejection was not influenced by HLA. The incidence of portal fibrosis could be analyzed in 62 1-yr biopsies and was higher after TVLTx than FSLTx (

P

= 0.04). The incidence of portal fibrosis after TVLTx with 0 or 1 mismatch at the HLA-DR locus was 100% compared to 43% with 2 mismatches (

P

= 0.004). After multivariate analysis, matching for HLA-DR and matching for TVLTx were independent risk factors for portal fibrosis. In conclusion, an overall beneficial effect of HLA matching, sharing CREGs, or sharing HLA-DR antigens was not observed. A negative effect was present for HLA-DR matching and sharing HLA-DR antigens on survival after TVLTx. HLA-DR matching might be associated with portal fibrosis in these grafts. (Liver Transpl 2005;11:1541–1549.)
Impact of cytomegalovirus prophylaxis on rejection following orthotopic liver transplantation
Authors: Slifkin Michelle , Ruthazer Robin , Freeman Richard , Bloom Judy , Fitzmaurice Susan , Fairchild Ralph , Angelis Michael , Cooper Jeffrey , Barefoot Laurie , Rohrer Richard , Snydman David R.
Published: November 2005

With improved cytomegalovirus (CMV) prophylaxis, CMV disease after liver transplantation has decreased dramatically, and patient and graft survival have improved. We examined the impact of CMV prophylaxis on biopsy proven rejection after orthotopic liver transplantation by analyzing data on 192 liver recipients over 5 years (1994–1999). Risk factors assessed for biopsy proven rejection including donor and recipient age, CMV serostatus; CMV prophylaxis; immunosuppression; bacteremia and blood product use were examined over a 2-year follow-up. Multivariate analysis of risk factors for rejection showed that bacteremia (HR 3.57, 95% CI 1.39–9.36,

P

=0.008), donor age (HR 1.20, 95% CI 1.06–1.36, per 10 year increase,

P

=0.004), and use of cyclosporine as initial immunosuppression compared to tacrolimus (HR 1.98, 95% CI 1.27–3.09, P=0.003) were associated with increased risk; ganciclovir prophylaxis for 3 months (HR 0.51, 95% CI 0.33 to 0.79,

P

=0.003) and recipient age (HR 0.78; 95% CI 0.63–0.96, for each 10 year increase,

P

=0.03) were associated with decreased risk. We conclude that, the use of CMV prophylaxis with ganciclovir significantly reduces the incidence of biopsy proven rejection in liver transplant recipients. (Liver Transpl 2005;11:1597–1602.)
Effects of hyperbaric oxygen exposure on experimental hepatic ischemia reperfusion injury: Relationship between its timing and neutrophil sequestration
Authors: Kihara Kenji , Ueno Shinichi , Sakoda Masahiko , Aikou Takashi
Published: November 2005

Recent studies have shown that hyperbaric oxygen therapy (HBOT) reduces neutrophil endothelial adherence in venules and also blocks the progressive arteriolar vasoconstriction associated with ischemia-reperfusion (I-R) injury in the extremities and the brain. In order to elucidate the effects of HBOT after I-R in digestive organs, particularly in the liver, we evaluated the following: 1) the relationship between timing of HBOT and tissue damage; and 2) HBOT's effects on neutrophil sequestration. Using a hepatic I-R (45 minute) model in male rats, survival rate, liver tissue damage, and neutrophil accumulation within the sinusoids in the HBOT-treated group (Group H) were compared to those in the nontreated group (Group C). For the HBOT-treated group, HBOT was administered as 100% oxygen, at 2.5 atm absolute, for 60 minutes. When HBOT was given 30 minute after I-R, the survival rate was much better in Group H than in Group C. HBOT performed within 3 hours of I-R markedly suppressed increases in the malondialdehyde level in tissues of the liver and lessened the congestion in the sinusoids. In addition, HBOT just after I-R caused decreased number of cells stained by the naphthol AS-D chloroacetate esterase infiltrating into the sinusoids. HBOT 3 hours after reperfusion, however, showed no clear effects upon neutrophil sequestration compared to Group C. These results indicate that HBOT performed within 3 hours of I-R alleviates hepatic dysfunction and improves the survival rate after I-R. Herein, we propose 1 possible mechanism for these beneficial effects: early HBOT given before neutrophil-mediated injury phase may suppress the accumulation of neutrophils after I-R. In conclusion, we believe that the present study should lead to an improved understanding of HBOT's potential role in hepatic surgery. (Liver Transpl 2005;11:1574–1580.)
Herpes simplex virus-associated acute liver failure: A difficult diagnosis with a poor prognosis
Authors: Ichai Philippe , Roque Afonso Anne Marie , Sebagh Mylène , Gonzalez Maria Eugenia , Codés Liana , Azoulay Daniel , Saliba Faouzi , Karam Vincent , Dussaix Elisabeth , Guettier Catherine , Castaing Denis , Samuel Didier
Published: November 2005

We report 5 cases of acute liver failure related to herpes simplex (HSV) infection in 1 immunocompetent and 4 immunosuppressed patients. One patient was too ill for liver transplantation indication. Three patients, among the 4 listed, underwent liver transplantation. Three patients died 11 days to 1 year after transplantation and 2 patients died 2 to 3 days after admission. All presented with fever and none with skin lesions. The diagnosis of HSV-related hepatitis was made antemortem in only 2 patients on the basis of positive blood cultures and/or immunohistochemic findings. In the remaining patients, HSV diagnosis was made retrospectively on further histologic and virologic investigations. Primary HSV infection was certain or likely in all cases, including an HSV2 superinfection of an anti-HSV1-positive patient and two HSV superinfections of hepatitis B virus (HBV)-related chronic liver disease. In these latter patients, HSV diagnosis was totally unsuspected, despite fever. HSV superinfection has significantly contributed to liver dysfunction aggravation and death. In conclusion, the diagnosis of HSV hepatitis is difficult to establish in the absence of specific clinical signs. This may suggest the need for early administration of acyclovir in patients with suspected HSV hepatitis, without waiting for virologic confirmation. Diagnosis methods providing fast results (real-time polymerase chain reaction [PCR]) should be implemented. (Liver Transpl 2005;11:1550–1555.)
Hepatic and intestinal schistosomiasis after orthotopic liver transplant
Authors: Hoare Matthew , Gelson William T.H. , Davies Susan E. , Curran Martin , Alexander Graeme J.M.
Published: November 2005

Schistosomiasis affects 200 to 250 million people worldwide. Hepatic schistosomiasis is a well-recognized cause of chronic liver disease and portal hypertension. There are no previous reports of schistosomiasis post liver transplantation. We report on 2 cases of schistosomiasis in liver transplant recipients— a case of gastric schistosomiasis and a case of hepatic schistosomiasis. A discussion of the pathology of schistosomal infection and a rationale for screening potential liver transplant recipients from endemic areas follows. (Liver Transpl 2005;11:1603–1607.)
Complications and use of intracranial pressure monitoring in patients with acute liver failure and severe encephalopathy
Authors: Vaquero Javier , Fontana Robert J. , Larson Anne M. , Bass Nathan M.T. , Davern Timothy J. , Shakil Obaid A. , Han Steven , Harrison Edwyn M. , Stravitz Todd R. , Muñoz Santiago , Brown Robert , Lee William M. , Blei Andres T.
Published: November 2005

Monitoring of intracranial pressure (ICP) in acute liver failure (ALF) is controversial as a result of the reported complication risk (˜20%) and limited therapeutic options for intracranial hypertension. Using prospectively collected information from 332 patients with ALF and severe encephalopathy, we evaluated a recent experience with ICP monitoring in the 24 centers constituting the U.S. ALF Study Group. Special attention was given to the rate of complications, changes in management, and outcome after liver transplantation (LT). ICP monitoring was used in 92 patients (28% of the cohort), but the frequency of monitoring differed between centers (

P

< 0.001). ICP monitoring was strongly associated with the indication of LT (

P

< 0.001). A survey performed in a subset of 58 patients with ICP monitoring revealed intracranial hemorrhage in 10.3% of the cohort, half of the complications being incidental radiological findings. However, intracranial bleeding could have contributed to the demise of 2 patients. In subjects listed for LT, ICP monitoring was associated with a higher proportion of subjects receiving vasopressors and ICP-related medications. The 30-day survival post-LT was similar in both monitored and nonmonitored groups (85% vs. 85%). In conclusion, the risk of intracranial hemorrhage following ICP monitoring may have decreased in the last decade, but major complications are still present. In the absence of ICP monitoring, however, patients listed for LT appear to be treated less aggressively for intracranial hypertension. In view of the high 30-day survival rate after LT, future studies of the impact of intracranial hypertension should also focus on long-term neurological recovery from ALF. (Liver Transpl 2005;11:1581–1589.)
Recurrent hepatic sarcoidosis post-liver transplantation manifesting with severe hypercalcemia: A case report and review of the literature
Authors: Cengiz Cem , Rodriguez-Davalos Manuel , deBoccardo Graciela , Fiel Isabel M. , Rodriguez-Laiz Gonzalo , Kovacevic Mark , Emre Sukru , Schiano Thomas
Published: November 2005

Sarcoidosis is a systemic granulomatous disease primarily involving the lungs, lymph nodes, skin, eyes and nervous system; liver involvement is asymptomatic in most cases. However, once the patient develops clinical symptoms liver disease is usually progressive and may necessitate orthotopic liver transplantation. There are a few reports of asymptomatic recurrent sarcoidosis developing within the liver allograft. We report a case of early recurrence of sarcoidosis in the liver allograft diagnosed on biopsy in a patient who presented with severe hypercalcemia, kidney dysfunction, and increase in size of abdominal lymph nodes. The liver chemistry tests were within normal limits. The patient responded well to steroid treatment by normalizing serum calcium and creatinine levels and reducing lymph node size. To date, there has been no report in the literature of symptomatic recurrence of hepatic sarcoidosis following orthotopic liver transplantation. (Liver Transpl 2005;11:1611–1614.)
Effects of Stereoregularity of Multiblock Copoly(rac‐lactide)s on Stereocomplex Microparticles and Their Insulin Delivery
Authors: Hu Junli , Tang Zhaohui , Qiu Xueyu , Han Yadong , Du Qing , Chen Xuesi , Jing Xiabin
Published: November 2005

Summary: Uniform stereocomplex microparticles ranging from nanometer to micrometer size are prepared by using stereo multiblock copoly(rac‐lactide)s (smb‐PLAs) with different stereoregularity. At comparable molecular weights, as the smb‐PLA stereoregularity decreases from 88% to 76%, the crystallinity of the microparticles decreases noticeably, as proved by DSC and WAXD. At the same time, the shape of the microparticles varies from the flower shape to the sphere shape and the particle size increases markedly from 700–2700 nm as shown by SEM. However, all insulin‐loaded microparticles are of cake‐shape and their sizes depend on the stereoregularity. The crystallization of smb‐PLAs facilitated by insulin is evidenced by the increase of Tm and ΔHf in DSC. The highest insulin‐loading content of 14.2% and ‐entrapment efficiency of 82.8% are obtained from the smb‐PLA with the highest stereoregularity of 88%. Release studies in vitro show the least first‐day release at about 25% followed by continuous release of another 70% of insulin over one month. Stereocomplex microparticles of smb‐PLAs with lower stereoregularity resulted in a relatively lower insulin‐entrapment efficiency and ‐loading content, a larger first‐day release, and also complete release of 90% of the total amount within one month. The release system follows a diffusion mechanism. By contrast, atactic PLA shows a very low entrapment efficiency of 16.7%.

Structure of a stereo multiblock copoly(rac‐lactide).

magnified image

Structure of a stereo multiblock copoly(rac‐lactide).
Cover Picture: Macromol. Chem. Phys. 23/2005
Authors: Zhang Wangqing , Shi Linqi , Miao Z.‐J. , Wu Kai , An Yingli
Published: November 2005

Cover: Schematic formation of core‐shell‐corona (CSC) micellar complexes by adsorption of PEG‐b‐P4VP onto core‐shell PS‐b‐PAA micelles. The PS blocks form the core of the micellar complexes, while the bonded PAA/P4VP blocks form the shell and PEG the corona. Further details can be found in the Full Paper by W.‐Q. Zhang, L.‐Q. Shi*, Z.‐J. Miao, K. Wu, and Y. An on page 2354.
A New Method for Producing High Melt Strength Poly(propylene) with a Reactive Extrusion
Authors: Ohnishi Rikuo , Fujimura Takenori , Tsunori Ryoichi , Sugita Yasuhisa
Published: November 2005

Summary: A new class of melt blend material was prepared by extruding a mixture of 3‐aminopropyltriethoxysilane (APTES), maleic anhydride‐grafted poly(propylene) (PP‐g‐MA) with different molecular weight and MA content and poly(propylene) powder produced with a TiCl3‐based catalyst (PP‐A). A suitable selection of PP‐g‐MA provided extremely high melt strength (MS) of resultant blend materials. Such a superior melt property was caused by the synergy between the present melt reaction and the higher molecular weight portion containing PP‐A. The gel content measurements of typical blend materials and PP‐g‐MA/APTES blends indicated that an excessive amount of inert PP suppresses the formation of gels. The reaction between PP‐g‐MA and APTES was then investigated by analyzing crystalline polymer fractions separated from the atactic PP/PP‐g‐MA/APTES and atactic PP/PP‐g‐MA blends. The FT‐IR analysis of the fractions revealed that the NH2 group in APTES readily reacts with MA grafted on PP and the reaction leads to the formation of imide linkage. Moreover, the GPC analysis of the fraction showed that higher molecular weight polymers were formed in the presence of APTES. Since a trace amount of water surely produces in the vicinity of active silyltriethoxy groups during the reactive extrusion, such polymers were formed by the condensation between hydrolyzed APTES‐grafted polymer chains. These results led us to the conclusion that long‐chain‐branched PP (LCB‐PP) was certainly produced and its formation is essential for the increase in MS of the present blend materials.

Relationship between log(MS) and log(MFR) for PP/PP‐g‐MA/APTES and commercial PP resins.

magnified image

Relationship between log(MS) and log(MFR) for PP/PP‐g‐MA/APTES and commercial PP resins.
Preparation of Polymer Nanofibers Containing Silver Nanoparticles by Using Poly(N‐vinylpyrrolidone)
Authors: Jin Wen‐Ji , Lee Hwang Kyu , Jeong Eun Hwan , Park Won Ho , Youk Ji Ho
Published: November 2005

Summary: Poly(N‐vinylpyrrolidone) (PVP) was used in two methods to prepare polymer nanofibers containing Ag nanoparticles. The first method involved electrospinning the PVP nanofibers containing Ag nanoparticles directly from the PVP solutions containing the Ag nanoparticles. N,N‐Dimethylformamide was used as a solvent for the PVP as well as a reducing agent for the Ag+ ions in the PVP solutions. In the second method, poly(vinyl alcohol) (PVA) aqueous solutions were electrospun with 5 wt.‐% of the PVP containing Ag nanoparticles. The Ag nanoparticles were evenly distributed in the PVA nanofibers. PVP containing Ag nanoparticles could be used to introduce Ag nanoparticles to other polymer nanofibers that are miscible with PVP.

TEM image of a PVA nanofiber electrospun with 5 wt.‐% of the PVP containing Ag nanoparticles.

image

TEM image of a PVA nanofiber electrospun with 5 wt.‐% of the PVP containing Ag nanoparticles.
Concentration‐Dependent Self‐Assembly of a Novel Comb Oligomer Having Rigid Binaphthyl Macrocyclic Pendants
Authors: Liu Na , Wang Xing , Cao Hui , Chen Chunhai , Zhang Wanjin , Wei Yen
Published: November 2005

Summary: The synthesis and self‐assembly of a comb oligomer having rigid racemic binaphthyl macrocyclic pendant groups are described. The coupling of two structural motifs at the molecular level, e.g., a nanometer‐size chiral cavity, and a flexible polymeric backbone, could lead to new opportunities in molecular recognition and separation. The macrocyclic monomers were synthesized followed by introduction of an acrylate side‐group, and through free‐radical polymerization, they yielded a comb oligomer. Most importantly, this novel oligomer can self‐assemble into solid or hollow spheres when tetrahydrofuran (THF) solutions of the oligomer at different concentrations are dropped onto the surface of water. The morphology of the solid or hollow spheres was observed by TEM, ESEM and DLS.

A schematic illustration of the processes of self‐assembly of the oligomer.

image

A schematic illustration of the processes of self‐assembly of the oligomer.
Cover Picture: Macromol. Rapid Commun. 23/2005
Authors: Champion Richard D. , Cheng Kai‐Fang , Pai Chia‐Ling , Chen Wen‐Chang , Jenekhe Samson A.
Published: November 2005

Cover: The quinoxaline‐thiophene donor‐acceptor copolymer PTHQx was found to be a p‐channel semiconductor in thin‐film field‐effect transistors. The measured electrical output and transfer characteristics of the thin‐film transistors revealed a high mobility of holes and an on/off current ratio of 6 × 105. Further details can be found in the Communication by R. D. Champion, K.‐F. Cheng, C.‐L. Pai, W.‐C. Chen,* and S. A. Jenekhe* on page 1835.
Dual in vivo magnetic resonance evaluation of magnetically labeled mouse embryonic stem cells and cardiac function at 1.5 t
Authors: Arai Takayasu , Kofidis Theo , Bulte Jeff W. M. , de Bruin Jorg , Venook Ross D. , Berry Gerald J. , Mcconnell Michael V. , Quertermous Thomas , Robbins Robert C. , Yang Phillip C.
Published: November 2005

Cell therapy has demonstrated the potential to restore injured myocardium. A reliable in vivo imaging method to localize transplanted cells and monitor their restorative effects will enable a systematic investigation of this therapeutic modality. The dual MRI capability of imaging both magnetically labeled mouse embryonic stem cells (mESC) and their restorative effects on cardiac function in a murine model of acute myocardial infarction is demonstrated. Serial in vivo MR detection of transplanted mESC and monitoring of the mESC‐treated myocardium was conducted over a 4‐week period using a 1.5 T clinical scanner. During the 4‐week duration, the mESC‐treated myocardium demonstrated sustained improvement of the left ventricular (LV) ejection fraction and conservation of LV mass. Furthermore, no significant difference of their restorative effects on the cardiac function was created by the magnetic labeling of mESC. Thus, in vivo MRI enables simultaneous detection of transplanted mESC and their therapeutic effect on the injured myocardium. Magn Reson Med 2006. © 2005 Wiley‐Liss, Inc.
Localized in vivo isotropic‐anisotropic correlation 1H NMR spectroscopy using ultraslow magic angle spinning
Authors: Wind Robert A. , Hu Jian Z. , Majors Paul D.
Published: November 2005

In a previous work (1), the susceptibility broadening in the 1H NMR metabolite spectrum obtained in a live mouse was separated from the isotropic information, which significantly increased the spectral resolution. This was achieved using ultraslow magic angle spinning (MAS) of the animal combined with a modified phase‐corrected magic angle turning (PHORMAT) pulse sequence. However, PHORMAT cannot be used for spatially selective spectroscopy. This article introduces a modified sequence called localized magic angle turning (LOCMAT) that makes this possible. Proton LOCMAT spectra were obtained from the liver and heart of a live mouse while the animal was spun at a speed of 4 Hz in a 2 Tesla field. It was found that even in this relatively low field, LOCMAT provided isotropic line widths that were a factor of 4–10 times smaller than those obtained in a stationary animal. Furthermore, the susceptibility broadening of the heart metabolites showed unusual features that are not observed in dead animals. The limitations of LOCMAT and possible ways to improve the technique are discussed. It is concluded that in vivo LOCMAT can significantly enhance the utility of NMR spectroscopy for biomedical research. Magn Reson Med, 2006. Published 2005 Wiley‐Liss, Inc.
Optimal control of parametrically excited linear delay differential systems via Chebyshev polynomials
Authors: Deshmukh Venkatesh , Ma Haitao , Butcher Eric A.
Published: November 2005

The use of Chebyshev polynomials in solving finite horizon optimal control problems associated with general linear time‐varying systems with constant delay is well known in the literature. The technique is modified in the present paper for the finite horizon control of dynamical systems with time periodic coefficients and constant delay. The governing differential equations of motion are converted into an algebraic recursive relationship in terms of the Chebyshev coefficients of the system matrices, delayed and present state vectors, and the input vector. Three different approaches are considered. The first approach computes the Chebyshev coefficients of the control vector by minimizing a quadratic cost function over a finite horizon or a finite sequence of time intervals. Then two convergence conditions are presented to improve the performance of the optimized trajectories in terms of the oscillation of controlled states within intervals. The second approach computes the Chebyshev coefficients of the control vector by maximizing a quadratic decay rate of the L2 norm of Chebyshev coefficients of the state subject to linear matching and quadratic convergence conditions. The control vector in each interval is computed by formulating a non‐linear optimization programme. The third approach computes the Chebyshev coefficients of the control vector by maximizing a linear decay rate of the L∞ norm of Chebyshev coefficients of the state subject to linear matching and linear convergence conditions. The proposed techniques are illustrated by designing regulation controllers for a delayed Mathieu equation over a finite control horizon. Copyright © 2005 John Wiley & Sons, Ltd.
Biomechanics of bones on various length scales
Authors: Nackenhorst Udo , Lenz Christian
Published: November 2005

Bone are characterized by a hierarchical internal structure starting from the distinction between trabecular and cortical bone going over the osteonal structure of cortical bone down to the basic composite material with a soft collagenous matrix and a mineralized phase. Furthermore, bones have to be understood as organisms which adapt themselves to the mechanical demand. Phenomenological approaches for computations of stress adaptive bone remodeling based on a continuums description have been discussed intensively in literature. Goal of this presentation is a more detailed strategy for the explanation of the biomechanical interaction in more detail. A strain driven bone remodeling theory is presented, where three characteristic length scales including models for the bone cells are considered. A computational method for a closed loop biomechanical control circuit of bone remodeling is presented. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic multi‐layer models of dry friction
Authors: Geike Thomas , Popov Valentin
Published: November 2005

Determining the friction law between solids as a function of material and loading parameters remains a topical and still unsolved problem of tribology. In the rail‐wheel‐contact the law of sliding friction determines not only the maximum tractive forces but also defines the conditions for the occurrence of instabilities.

Recent simulations of irreversible processes in micro‐contacts with the method of movable cellular automata (MCA) have shown that dynamic aspects do play an essential role in these processes. Inelastic processes of plastic deformation, detaching of particles and their reintegration into the surfaces as well as processes of mechanical mixing occur only in a thin surface layer called quasi‐fluid layer. Studying the properties of the quasi‐fluid layer is thus a key for understanding friction.

To better understand the physical nature of the quasi‐fluid layer and especially the physical nature of the viscosity of the quasi‐fluid state, multi‐layer models of an elasto‐plastic solid have been studied. In the layer model it becomes particularly clear that the physical reason for occurrence of the quasi‐fluid layer is the bi‐stability of the friction law between layers. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Plastification and Damage in Wheel‐Rail Rolling Contact – Case Study on a Crossing
Authors: Wiest Martina , Daves Werner , Fischer Franz Dieter , Ossberger Heinz
Published: November 2005

A fully three‐dimensional, dynamic model for a wheel running over a crossing is developed using an explicit finite element program. The full mass of the wheel and the crossing and elastic‐plastic material behaviour are considered. The damage in the contact area is investigated with a very dense mesh taken from the dynamic model using a submodelling technique. With this kind of calculations the stresses and strains produced in the wheel and the crossing during the cross‐over process can be determined, as well as the respective reaction forces in the bedding and the axle. Calculations for different crossing‐geometries are performed. Finally a damage indicator is introduced to identify the probable location of crack initiation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Homogenization in the Theory of Viscoplasticity
Authors: Nesenenko Sergiy
Published: November 2005

We study the homogenization of the quasistatic initial boundary value problem with internal variables which models the deformation behavior of viscoplastic bodies with a periodic microstructure. This problem is represented through a system of linear partial differential equations coupled with a nonlinear system of differential equations or inclusions. Recently it was shown by Alber [2] that the formally derived homogenized initial boundary value problem has a solution. From this solution we construct an asymptotic solution for the original problem and prove that the difference of the exact solution and the asymptotic solution tends to zero if the lengthscale of the microstructure goes to zero. The work is based on monotonicity properties of the differential equations or inclusions. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Conjugation of two functional groups through an unsaturated system
Authors: Exner Otto , Böhm Stanislav
Published: November 2005

Energies of 51 1‐(E),4‐(E)‐disubstituted 1,3‐butadienes (1), 36 1,4‐disubstituted benzenes (2) and 36 (E)‐1,2‐disubstituted ethenes (3) with dipolar substituents were calculated at the B3LYP/6–311 + G(d,p) level and evaluated in terms of isodesmic reactions expressing the interaction of substituents through the conjugated system. The energy of interaction reaches up to 40 kJ mol−1, it is roughly similar in the three series and most regular in the series 1. While its correlation within the framework of dual substituent parameter analysis lacks physical meaning, it is possible to separate the conjugative (resonance) component by subtracting the inductive component with reference to 1,4‐disubstituted bicyclo[2.2.2]octanes 4. The conjugative interaction is strongly stabilizing for the combination acceptor–donor and destabilizing for two donors; in these cases it is parallel to changes of geometry as they are predicted by the common resonance equations. Interaction of two acceptors is weak; in addition, there are groups that cannot be classified either as donors or as acceptors. Therefore, one can construct a scale of the resonance ability of donors in conjugation with an acceptor and vice versa, but it is not possible to express the interaction of two donors or of two acceptors on a unified scale for all substituents. The resonance description is certainly appropriate for the typical examples (interaction of NO2 and NH2) but should not be generalized to all possible structures. Copyright © 2005 John Wiley & Sons, Ltd.
Cancer‐related communication between female patients and male partners scale: a pilot study
Authors: Kornblith Alice B. , Regan Meredith M. , Kim Youngmee , Greer Greta , Parker Beverly , Bennett Samantha , Winer Eric
Published: November 2005

Background: The study's objective was to evaluate the reliability and validity of the Cancer‐Related Communication Problems within Couples Scale (CRCP), a measure to assess whether patients and their partners have difficulty talking about cancer with each other.

Methods: The CRCP Scale included 18 items concerning open communication/emotional support, treatment‐specific issues, self‐protection, and protective buffering. Patients and partners responded through the American Cancer Society's website and mailed questionnaires through Y‐ME. The CRCP's validity was tested using the Hospital Anxiety and Depression Scale (HADS) and the Dyadic Adjustment Scale (DAS, marital relationship).

Results: 189 female patients and 135 male partners participated in the survey. Three items were deleted based on lack of clarity or an item not being applicable to many respondents, resulting in a 15 item scale. The number of CRCP problems' internal consistency in the 15 item scale was good for both patients and partners (alpha coefficient=0.87, 0.81, respectively). The number of patients' CRCP problems correlated with the DAS (p<0.0001), and the number of partners' CRCP problems correlated with the HADS (p<0.0001) and the DAS (p<0.0001).

Conclusion: Analyses supported the CRCP Scale's reliability and validity for female cancer patients and male partners. Copyright © 2005 John Wiley & Sons, Ltd.
Application of the theory of planned behavior to understand intentions to engage in physical and psychosocial health behaviors after cancer diagnosis
Authors: Andrykowski Michael A. , Beacham Abbie O. , Schmidt John E. , Harper Felicity W. K.
Published: November 2005

A cancer diagnosis can trigger change in both lifestyle behaviors and mental health outcomes such as ‘growth’ and ‘benefit‐finding’. Assuming changes in mental health outcomes are based upon changes in specific behaviors, the Theory of Planned Behavior (TPB) may facilitate understanding of post‐diagnosis change in physical and psychosocial ‘health’ behaviors. Adults (n=130) ⩽2 years post‐cancer diagnosis completed an internet survey. Current performance and future behavior intentions for two physical (e.g. eating a healthy diet) and four psychosocial (e.g. spending quality time with family/friends; engaging in spiritual or religious activities) health behaviors were assessed. TPB constructs (subjective norm, behavior attitudes, perceived behavioral control) for each of the six behaviors were also assessed. Multiple regression analyses indicated the set of TPB constructs accounted for an increment of 25–53% of variance in behavioral intentions beyond that accounted for by clinical and demographic variables. Among individual TPB constructs, behavioral attitude was most consistently associated with behavioral intentions while subjective norm was least consistently associated with behavioral intentions. The TPB could serve as a comprehensive model for understanding change in both physical and psychosocial health behaviors after cancer diagnosis and could suggest innovative approaches to developing interventions to enhance post‐diagnosis ‘growth’ and ‘benefit finding’. Copyright © 2005 John Wiley & Sons, Ltd.
Palliative or curative treatment intent affects communication in radiation therapy consultations
Authors: Timmermans Liesbeth M. , van der Maazen Richard W. M. , Leer Jan Willem H. , Kraaimaat Floris W.
Published: November 2005

Objective: To assess whether communication in radiotherapy consultations is affected by palliative or curative treatment intent.

Subjects and methods: The study involved 160 patients and 8 radiation oncologists. Eighty patients visited the radiation oncologist (RO) for palliative treatment and 80 for curative treatment. The consultation prior to radiation treatment was analyzed with the Roter Interaction Analysis System (RIAS). Within three days, patients completed a quality of life questionnaire (EORTC‐QLQ‐C30).

Results: In palliative radiotherapy (PRT) consultations, ROs asked more (closed‐ended) biomedical and psychosocial questions and provided more information on prognosis than in consultations for curative radiotherapy (CRT). Patients in both groups provided a great deal of psychosocial information but asked few questions. The ROs expressed more concerns in the PRT consultations, while patients did not. PRT patients received fewer supportive remarks than CRT patients. In both groups, explicit decision‐making received little attention. Proxies who accompanied the patients took a more active role in PRT than in CRT consultations.

Conclusion: Communication in radiotherapy is affected by treatment intent with respect to the main contents of the consultation. Copyright © 2005 John Wiley & Sons, Ltd.
Does felt age reflect health‐related quality of life in cancer patients?
Authors: Boehmer Sonja
Published: November 2005

Subjective age is related to health and to life satisfaction. The present study on post‐surgical cancer patients addressed two questions: (1) Do people differ in their health‐related quality of life (HRQOL) depending on their felt age? (2) Is change in felt age associated with change in HRQOL? Data were collected at one month (T1) and six months (T2) after surgery (N=159; 58% men, aged 24–86 years). At both waves, less than 14% of the patients felt older than their chronological age. Patients who felt younger than their age and patients who felt as old as they were reported better HRQOL than those subjectively feeling older. Between T1 and T2, an increment of felt age was found in 29% and a decrement in 28% of cases. HRQOL improved also among those who subjectively aged and among those whose felt age did not change, but in fewer aspects and with substantially lower effect sizes than among those whose felt age decreased. HRQOL is a correlate of felt age. However, an increment in felt age does not imply a decrease of HRQOL. Copyright © 2005 John Wiley & Sons, Ltd.
Exploring the vulnerability of asylum seekers in the UK
Authors: Stewart Emma
Published: November 2005

Asylum seekers living in the UK are identified as a vulnerable group in contemporary society. Empirical results from in‐depth interviews are drawn upon in the paper to uncover the everyday experiences of asylum seekers. This material is then employed to engage critically with the concept of ‘vulnerability’. Three main themes specifically structure the discussion: the interstitial position of asylum seekers in the nation state is explored; the spatial manifestations of vulnerability are identified; and the responses of individuals to their ‘vulnerable’ situation are highlighted. By drawing upon the specific example of this illustrative group, important theoretical implications for the understanding of ‘vulnerability’ are proposed. These include the importance of time–space relative to vulnerable populations and the potential cumulative effect of vulnerability. Finally, questions are raised as to how researchers investigate and represent ‘vulnerable’ populations. Copyright © 2005 John Wiley & Sons, Ltd.
Editorial: vulnerable spatialities
Authors: Findlay Allan M.
Published: November 2005

The tsunami of 26 December 2004 provided an empirical lens to explore the multiple geographical dimensions of population vulnerability. Examining the global reach of the tsunami provides a useful starting point in researching the changing spatial significance of events such as this. Defining spatial vulnerabilities is, however, very problematic, especially when producing conventional metrics such as measuring the death rate is so difficult. The paper explores the spatialities of vulnerability relative to what is knowable about the political, economic and social contexts of vulnerable peoples'. It is argued that ‘spatial context’ needs to be conceptualised as contingent, and that relational understandings can help to understand how vulnerabilities, including those associated with the tsunami, are represented. While relational thinking has profound implications for how spatial vulnerabilities are studied by researchers working amongst communities at risk, the article closes by recommending that population researchers maintain a pluralistic vision of research praxis. In discussing these issues the article also provides a conceptual framework within which the work of other geographers in general, and the contributions of other papers in this special issue in particular, may be located. Copyright © 2005 John Wiley & Sons, Ltd.
Tests by TEM contrast simulations of the elastic field of a buried (001) low angle twist boundary in silicon
Authors: Boussaïd Ahlem , Fournel Frank , Bonnet Roland
Published: November 2005

A buried (001) low angle twist boundary (misorientation angle 0.48°) in silicon is investigated by the technique of two‐beam transmission electron microscopy using bright‐field images obtained from diffracting vectors g{400}, g{311} and g{220}, and g{nnn} with n = 3 and 4. To analyse its elastic field, the concept of interfacial “relaxation centres” is assumed, for which the relative displacement field of the two crystals is zero. These centres are located in the middle of each square formed by a dislocation unit cell. This assumption is tested positively for the first time for a double periodic network of screw dislocations. For the image contrast calculations, the elastic field of the network is that of two perpendicular families of screw misfit dislocations in the sense of Bonnet (1981). Since the two‐beam bright‐field approximation is weak to explain the experimental images taken with g{nnn} and n = 3 and 4, extra N beam image calculations involving N < 7 systematic reflections along g{nnn} have been carried out with a devoted programme. All the computed images prove to be in good agreement with the experimental images, still validating the adopted elastic field. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A novel tapping SNOM: Specifications and performances
Authors: Longo G. , Girasole M. , Cricenti A.
Published: November 2005

A new scanning near field optical microscope operating in the intermittent contact mode (Tapping SNOM) using a non‐bent optical fiber is presented. The main advantages in terms of versatility and quality of the collected signal are described together with some results obtained studying fluorescence on material science samples and spectroscopy images of living cells. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical response of Ag‐induced reconstructions on vicinal Si(111)
Authors: Chandola S. , Jacob J. , Fleischer K. , Vogt P. , Richter W. , McGilp J. F.
Published: November 2005

The optical response of the Si(111)‐(3 × 1)–Ag surface has been studied for the first time with reflectance anisotropy spectroscopy (RAS). A single domain surface was obtained by depositing <1 ML of Ag onto a vicinal Si(111) substrate at 870 K. A significant optical anisotropy develops around 2.2 eV which is related to the formation of the 3 × 1 structure. This surface was then used as a template to grow one‐dimensional (1D) arrays of Ag nanodots, and also 3D Ag islands, by depositing 0.5 ML, and higher, coverages of Ag at room temperature. RAS of these structures showed a different response in the 2.2 eV region, with a broadened and reduced anisotropy. By extending the RA spectra into the infra‐red region (0.5–1.5 eV), substantial differences between the structures were observed below 1 eV, which may be linked to a difference in the metallic character of the nanodots and islands. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Out‐of‐plane scattering properties of long‐range surface plasmon polariton gratings
Authors: Søndergaard T. , Bozhevolnyi S. I.
Published: November 2005

Long‐range surface plasmon polariton (LRSPP) gratings are studied theoretically via the Lippmann–Schwinger integral equation method. The gratings are composed of a thin gold film (15 nm), which works as a waveguide for LRSPP waves, and an array of equidistant gold ridges on each side of the film designed for Bragg scattering into LRSPP waves at wavelengths around 1550 nm. Out‐of‐plane scattering (OUPS), transmission and reflection into LRSPP waves, and absorption, are investigated with respect to the wavelength, the height of the ridges, and the length of the grating. In particular we calculate the fraction of the light which is lost due to OUPS, and find an asymmetry in the OUPS with respect to wavelength across the bandgap. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of the GaAs(001)‐c(4 × 4) surface: direct analysis of the surface dielectric function
Authors: Hogan C. , Del Sole R.
Published: November 2005

We present a systematic analysis of the reflectance anisotropy (RA) spectrum of the GaAs(001)‐c(4 × 4) surface. In contrast to previous studies where RA spectra were resolved in real space by means of a layer‐by‐layer decomposition, we examine directly the more physically accessible surface dielectric function anisotropy. The method gives immediate information about the origin of structures in the RA spectrum, easily distinguishing between adsorptive and dissipative effects. A detailed explanation of the origin of bulk‐related features in the RA spectrum of this surface is also presented. Further evidence is provided of the existence of a c(4 × 4) reconstruction featuring mixed Ga–As dimers in the top layer. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First‐principles optical spectra of low dimensional systems
Authors: Chiodo Letizia , Bruno Mauro , Palummo Maurizia , Monachesi Patrizia
Published: November 2005

Low dimensional systems, such as organic molecules, nanotubes, nanowires, have attracted great interest in the last few years, due to their possible application in nanodevices. It is therefore important to describe accurately the electronic excitations, with highly reliable and efficient ab‐initio approaches. A standard technique for studying the ground‐state properties is the Density Functional Theory; however when electronic excited states are involved, the many‐body Green's functions theory is used for obtaining quasi‐particle excitation energies and optical spectra. In this paper we will present the current status of this theoretical and computational approach, showing results for a bulk semiconductor and for two different kinds of low dimensional systems. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)