bluuebunny/crossref_metadata_2025 huggingface dataset:
Age‐associated mitochondrial dysfunction in skeletal muscle: Contributing factors and suggestions for long‐term interventions
Authors: Huang Julianna H. , Hood David A.
Published: February 2009

It has been established that the impairment of mitochondrial function is associated with various disorders, such as type 2 diabetes and Alzheimer's disease. In addition, mitochondria have been implicated in the progression of cellular aging through a multitude of studies that connect increased mitochondrial dysfunction, such as increased reactive oxygen species production and decreased ATP synthesis, with skeletal muscle undergoing sarcopenia. Studies reveal an inverse relationship between mitochondrial biogenesis and aging such that as an individual increases in age, mitochondrial function, and content decreases. This review aims to summarize the relationship of mitochondria with skeletal muscle function, the regulation of mitochondrial biogenesis, and the alterations in skeletal muscle and mitochondrial function that result due to the aging process. © 2009 IUBMB IUBMB Life, 61(3): 201–214, 2009
Death receptor 5‐recruited raft components contributes to the sensitivity of Jurkat leukemia cell lines to TRAIL‐induced cell death
Authors: Min Yifan , Shi Juan , Zhang Yaxi , Liu Shilian , Liu Yanxin , Zheng Dexian
Published: February 2009

In the present study we demonstrated Jurkat leukemia cell lines of TIB152 and TIB153 with different sensitivities to recombinant soluble TRAIL cytotoxicity. TRAIL receptor death receptor 5 (DR5) was constitutively localized in the rafts in both cell lines. FADD, caspase‐8, and PI3K‐p85 subunit were recruited into DR5 lipid rafts of TIB152 but not in TIB153 cells. The expression and enzyme activity of acid sphingomyelinase, which digests sphingomyeline to produce ceramide and plays an essential role in lipid raft assembling, were higher in the rafts of TIB152 than in TIB153. These data provide evidences that DR5‐recruited raft components contribute to the different sensitivity of Jurkat leukemia cell lines to TRAIL‐induced cell death and may throw some light on the development of better therapeutic strategies for the cancer cells resistant to TRAIL treatment. © 2009 IUBMB IUBMB Life, 61(3): 261–267, 2009
RNase P RNA‐mediated cleavage
Authors: Kirsebom Leif A. , Trobro Stefan
Published: February 2009

Structural representation of the interactions between RNase P RNA (top) and a precursor tRNA substrate (bottom). See RNase P RNA‐mediated Cleavage by Kirsebom and Trobro, pp. 189–200.
Notes on quantitative structure‐properties relationships (QSPR) part 2: The role of the number of atoms as a molecular descriptor
Authors: Carbó‐Dorca Ramon , Saliner Ana Gallegos
Published: February 2009

A previous analysis performed in our laboratory about the polynomial dependency of the atomic quantum self‐similarity measures on the atomic number, together with recent publications on quantitative structure‐properties relationships (QSPR), based on the number of molecular atoms, published by various authors, have driven us to show here that a simplified form of the fundamental quantum QSPR (QQSPR) equation, permits to theoretically demonstrate the important, but obvious, role of the number of atoms in a molecule, as a possible molecular descriptor. A discussion of the practical use of the number of atoms in QSPR is also given at the end, which also contains a discussion on the role of Ockham's razor in descriptor simplification choices. © 2009 Wiley Periodicals, Inc. J Comput Chem 2009
Perfect planar tetracoordinate carbon in neutral unsaturated hydrocarbon cages: A new strategy utilizing three‐dimensional electron delocalization
Authors: Wang Yang
Published: February 2009

A new series of unsaturated pure and boron‐substituted hydrocarbons containing a perfect planar tetracoordinate carbon (ptC) have been proposed by performing density functional computations. The ptC is effectively stabilized through three‐dimensional delocalization of ptC's lone pair into π‐conjugated systems, by utilizing a new strategy opening a brand new way of designing ptC structures. Compared to previously proposed ptC‐containing hydrocarbon cage compound, a neutral hydrocarbon designed here might be a more viable target for synthetic attempts. © 2009 Wiley Periodicals, Inc. J Comput Chem 2009
Substituent effect on electron affinity, gas‐phase basicity, and structure of monosubstituted propynyl radicals and their anions: A theoretical study
Authors: Lee Gab‐Yong
Published: February 2009

The substituent effect of electron‐withdrawing groups on electron affinity and gas‐phase basicity has been investigated for substituted propynl radicals and their corresponding anions. It is shown that when a hydrogen of the α‐CH3 group in the propynyl system is substituted by an electron‐withdrawing substituent, electron affinity increases, whereas gas‐phase basicity decreases. These results can be explained in terms of the natural atomic charge of the terminal acetylene carbon of the systems. The calculated electron affinities are 3.28 eV (•CCCH2F), 3.59 eV (•CCCH2Cl) and 3.73 eV (•CCCH2Br), and the gas‐phase basicities of their anions are 359.5 kcal/mol (−:CCCH2F), 354.8 kcal/mol (:CCCH2Cl) and 351.3 kcal/mol (−:CCCH2Br). It is concluded that the larger the magnitude of electron‐withdrawing, the greater is the electron affinity of radical and the smaller is the gas‐phase basicity of its anion. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009
Condensation of substituted 2‐aminopyridine with β‐ketocarboxylic esters: 4H‐pyrido[1,2‐a]pyrimidin‐4‐ones and pyridin‐2‐ones
Authors: Ferrarini Pier Luigi , Mori Claudio , Manera Clementina , Mori Filippo , Calderone Vincenzo , Martinotti Enrica
Published: February 2009

We report the condensation of substituted 2‐aminopyridines 5 with β‐ketocarboxylic esters in polyphosphoric acid. In this reaction were obtained together with the target compounds, 4H‐pyrido[1,2‐a]pyrirnidin‐4‐ones 6 also the pyridin‐2‐ones 7. All the compounds 7 were tested for their calcium‐antagonistic activity but failed to evoke any vasorelaxant response.
Synthesis of quinolines by ruthenium‐catalyzed heteroannulation of anilines with 3‐amino‐1‐propanol
Authors: Cho Chan Sik , Oh Byoung Ho , Shim Sang Chul
Published: February 2009

Anilines react with 3‐amino‐1‐propanol in dioxane in the presence of a catalytic amount of a ruthenium catalyst and tin(II) chloride dihydrate together with a hydrogen acceptor to afford the corresponding quinolines in moderate yields.
Synthesis and application of ethyl 3‐(4‐dialkylaminophenyl)‐2‐(quinoxalin‐3(4H)‐on‐2‐yl)propenoates and related products
Authors: Rangnekar D. W. , Kanetkar V. R. , Shankarling G. S. , Malanker J. V. , Shanbhag C. R.
Published: February 2009

Ethyl quinoxalin‐3(4H)‐on‐2‐ylacetate was prepared by the condensation of 1,2‐diaminobenzene and diethyl oxalacetate (sodium salt). The key quinoxaline intermediate was condensed with a variety of 4‐dialkylaminobenzaldehydes/substituted benzaldehydes to yield novel brilliant quinoxalin‐2‐yl styryl dyes which were applied on polyester fibers as disperse dyes and their dyeing properties were studied.
Attempted syntheses of aminofluorothiophenes
Authors: Kobarfard Farzad , Kauffman Joel M. , Boyko Walter J.
Published: February 2009

It appeared that a key intermediate for 2‐amino‐3‐fluorothiophene (1), methyl 3‐fluorothiophene‐2‐carboxylate (5), had been prepared by a Schiemann reaction of the 3‐diazonium salt (6) in xylenes. This report was not correct. Gomberg coupling products 7 with o‐xylene are actually formed. We were able to prepare 5 by using special conditions for the Schiemann reaction. The hydrazide derivative of 5 failed to give 1 under Curtius reaction conditions. Two new acetamidofluorothiophene compounds were prepared using SelectfluorTM as the fluorinating agent, but no aminofluorothiophenes 1‐3 or salts could be obtained by acidic hydrolysis of either amide.
Synthesis of crown ethers containing a thiazole subcyclic unit
Authors: Kim Hong‐Seok , Kwon Ii‐Chun , Choi Jun‐Hyeak
Published: February 2009

Crown ethers containing a thiazole subcyclic unit are prepared from the reactions of 1,3‐bis[2(4‐hydroxymethylthiazoyl)]benzene with di‐p‐tosylates of corresponding di, tri, tetra, pentaethylene glycols in the presence of potassium hydride. However, if the cavity size in the ring system is small, [2+2] cyclization adduct also is formed.
Synthesis of bipyrazoles and pyrazoloisoxazoles from 3‐acetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one
Authors: Bendaas Abderrahman , Hamdi Maâmar , Sellier Nicole
Published: February 2009

Phenylhydrazine or hydrazine react with 3‐acetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one (1) to give 4‐acetoacetyl‐3‐methylpyrazolin‐5‐ones 4. The synthesis of bipyrazoles and pyrazoloisoxazoles from 4 are reported.
Synthesis of [1,4]dioxino[2,3‐c]quinolines and [1,4]dioxepino‐[2,3‐c]quinolines and their 1‐sulfur analogues
Authors: Hiessböck Romana , Kratzel Martin
Published: February 2009

The synthesis of [1,4]dioxino[2,3‐c]quinolines and [1,4]dioxepino[2,3‐c]quinolines with restrained conformation of the piperidine ring, which represent 1,2,3,4‐tetrahydroquinolines containing two heteroatom substituents at positions 3 and 4, is described. In addition, the application of this approach for the synthesis of 1‐sulfur analogues is discussed. Both series are helpful tools for three‐dimensional quantitative structure‐activity relationship studies in the field of modulators of multidrug resistance.
Molecular structures, electronic spectra, and aromaticity of 1,6‐ and 1,8‐dioxa analogues of pyrene and benzo[a]pyrene. Semiempirical molecular orbital calculations
Authors: Kataoka Masahiro , Sato Tsuguo
Published: February 2009

The molecular structures of [1]benzopyrano[6,5,4‐def][1]benzopyran, [2]benzopyrano[7,8,1,def]‐1‐benzopyran, 1‐benzopyrano[6,5,4‐mna]xanthene, and 2‐benzopyrano[7,8,1‐mna]xanthene have been optimized by using the PM3 semiemperical MO method. These calculated molecules have been shown to be planar. Their aromaticity has been investigated by use of the HOMA index. The molecules are found to be less aromatic than the correspolding parednt hydrocarbons, pyrene and benzo[a]pyrene. The CNDO/S MO method has been used to interpret th experimental uv‐vis specrtoscopic data. The result of the PM3, CNDO/S and HOMA‐index clculations are in good arteement with the experimental data.
Synthesis of a‐ and d‐homoazasteroidalisoxazoles
Authors: Xenos Constantinos D. , Camoutsis Charalambos
Published: February 2009

The synthesis of the isomeric D‐homoazasteroido[3,2‐c]‐ (3) and ‐[2,3‐d]lisoxazoles (4) and A‐homoazasteroido[17,16‐c]isoxazole (6) are reported by the reaction of 2‐hydroxymethylene‐17α‐aza‐D‐homo‐5α‐androstan‐3,17‐dione (2) and 16‐hydroxymethylene‐3‐aza‐A‐homo‐4α‐androsten‐4,17‐dione (5) correpondingly with hydroxylammonium chloride.
Biological activation of bone‐related biomaterials by recombinant adeno‐associated virus vector
Authors: Nasu Tomonori , Ito Hiromu , Tsutsumi Ryosuke , Kitaori Toshiyuki , Takemoto Mitsuru , Schwarz Edward M. , Nakamura Takashi
Published: February 2009

Gene therapy is a promising clinical tool that is no longer limited as a method to supplement genetic deficits, but rather is considered reliable for delivering proteins to specific tissues or cells. Recombinant adeno‐associated virus (rAAV) vector is one of the most potent gene transfer vehicles. Many biomaterials have been used in reconstructive surgery, but their biological inactivity has limited their use. To overcome shortcomings of available bone‐related biomaterials, we investigated the combination of rAAV with biomaterials. Taking advantage of the method of lyophilizing rAAV onto biomaterials, we showed that an rAAV coating successfully induced β‐galactosidase protein expression by rat fibroblasts on hydroxyapatite, β‐tricalcium phosphate, and titanium alloy in vitro. β‐Galactosidase expression was detected for 8 weeks after implantation of rAAV‐coated hydroxyapatite into rat back muscles in vivo. A coating of bone morphogenetic protein‐2‐expressing rAAV induced significant de novo bone formation on hydroxyapatite in rat back muscles. Our study demonstrates that the combination of lyophilized rAAV and biomaterials presents a promising strategy for bone regenerative medicine. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res
Hepatitis B virus–specific CD4 T cell immunity after liver transplantation for chronic hepatitis B
Authors: Luo Ying , Lo Chung Mau , Cheung Cindy K. , Lau George K. , Wong John
Published: February 2009

Cellular immunity plays an important role in the long-term control of hepatitis B virus (HBV) infection. We studied the changes in HBV-specific CD4 T cell immunity after orthotopic liver transplantation (OLT) for chronic hepatitis B under antiviral prophylaxis. T cell proliferation and interferon-γ production in response to in vitro challenge with HBV-encoded antigens were tested in 40 OLT recipients without HBV recurrence and in 12 OLT recipients with HBV recurrence more than 1 year after transplantation, and they were compared to 40 subjects with chronic HBV infection and to 23 subjects with self-limited HBV infection. The frequency and magnitude of the HBV-specific CD4 T cell response were significantly lower in 40 OLT recipients with HBV clearance, but the T cell reactivity to mitogen (phytohemagglutinin) and recall antigen (tetanus toxoid) was maintained. In the 12 OLT recipients with HBV recurrence, however, the HBV-specific T cell immunity was enhanced to a level comparable to that of patients with chronic hepatitis B, and the level was dependent on the serum viral load. In conclusion, HBV-specific CD4 T cell immunity is antigen-driven and evanesces with viral clearance, hence providing a favorable milieu for reactivation once prophylaxis is withdrawn. The cellular immunity in recipients with recurrence is not significantly different from that of individuals with chronic hepatitis B.
Minichromosome maintenance protein-2–positive portal tract lymphocytes distinguish acute cellular rejection from hepatitis C virus recurrence after liver transplantation
Authors: Unitt Esther , Gelson William , Davies Susan E. , Coleman Nicholas , Alexander Graeme J. M.
Published: February 2009

Hepatitis C virus (HCV) is a leading indication for liver transplantation worldwide, but graft infection with HCV frequently leads to hepatic fibrosis. Acute cellular rejection (ACR) can be difficult to distinguish confidently from HCV, even with histology, but accurate diagnosis is critical because treatment of ACR may accelerate HCV-related graft injury. Immunohistochemistry was undertaken on 99 liver biopsies from 31 patients with HCV graft infection, 22 patients with ACR, and 11 patients with HCV infection and unexplained graft dysfunction to investigate whether lymphocyte expression of minichromosome maintenance protein-2 (Mcm-2), a marker of licensed cell cycle entry, assessed in a novel semiautomated system could distinguish between ACR and graft infection with HCV. The portal tract area was greater in ACR than in HCV graft infection (P = 0.027), but there was considerable overlap. However, both the number of Mcm-2–positive lymphocytes per portal tract and the number of Mcm-2–positive lymphocytes per millimeter squared of portal tract distinguished between ACR and HCV graft infection (P < 0.0001). A cutoff value of 107 positive cells per portal tract had a sensitivity of 81.8% and a specificity of 91.9% (positive predictive value of 66.67% and negative predictive value of 95.75%). Of 11 HCV-infected patients with an uncertain diagnosis, 7 were deemed ultimately to have HCV graft infection, and 4 had superimposed corticosteroid-responsive ACR. The number of Mcm-2–positive cells per portal tract and per millimeter squared of portal tract again distinguished clearly between the groups (P = 0.012). In conclusion, lymphocyte Mcm-2 expression is a useful adjunct to histology in differentiating between HCV graft infection and ACR. Patients with a low number of Mcm-2–positive portal tract lymphocytes are less likely to have ACR.
Living liver donor death related to complications of myeloma
Authors: Melloul Emmanuel , Dondero Federica , Paugam-Burtz Catherine , Bouadma Lila , Arnulf Bertrand , Belghiti Jacques
Published: February 2009

We report a donor death after right hepatectomy for living donor transplantation due to an undiagnosed myeloma. The 47-year-old donor, who was the 147th case performed in our department, was in excellent health without any abnormalities in the preoperative investigations. Despite an uneventful right hepatectomy without transfusion, the patient developed a partial thrombus of the inferior vena cava with a right proximal pulmonary trunk embolism on postoperative day 6. Subsequently, he developed multiorgan dysfunction leading to a coagulopathy, respiratory distress, and renal failure requiring hemodialysis and mechanical ventilation. This clinical scenario led us to suspect a hematological disorder. Immune electrophoresis showed a monoclonal peak of immunoglobulin G (8.7 g/L), a myelogram revealed an abnormally high level of dystrophic plasmocytes (more than 7%), and biopsies of salivary glands confirmed the diagnosis of immunoglobulin G kappa myeloma. The patient progressively deteriorated because of simultaneous hemorrhagic and infectious pulmonary complications resulting in septic shock. Despite an adequate combination of antimicrobial therapy and pleural drainage, the donor died on postoperative day 57 from multiple organ failure. This unusual cause of donor death after right hepatectomy reinforces the need for an extensive preoperative assessment. We advocate the addition of urinary protein loss and electrophoresis to the standard donor assessment protocol.
Effect of angiotensin II and bradykinin inhibition in rat reduced-size liver transplantation
Authors: Padrissa-Altés Susagna , Franco-Gou Rosa , Boillot Olivier , Serafín Anna , Rimola Antoni , Arroyo Vicente , Rodés Joan , Peralta Carmen , Roselló-Catafau Joan
Published: February 2009

This study examined whether angiotensin II (Ang II) blockers [Ang II type I receptor antagonist, Ang II type II receptor antagonist, and angiotensin converting enzyme (ACE) inhibitor] could reduce hepatic injury and improve regeneration in reduced-size orthotopic liver transplantation (ROLT) and whether the beneficial effects of ischemic preconditioning (PC) in ROLT could be explained by changes in Ang II. We show that small liver grafts generated Ang II after ROLT and that this was associated with increased angiotensinogen and ACE messenger RNA expression. Furthermore, inhibition of Ang II did not contribute to PC-induced protection in ROLT. All Ang II blockers reduced hepatic injury, but none of them promoted liver regeneration. Bradykinin (BK) receptor antagonist improved liver regeneration but did not reduce hepatic injury in ROLT. Finally, the combination of Ang II blockers and BK receptor antagonists in ROLT reduced hepatic injury and improved liver regeneration. In conclusion, treatments with either Ang II blockers or BK receptor antagonists cannot, on their own, improve the outcome of ROLT. Although Ang II blockers can reduce hepatic ischemia-reperfusion injury and BK receptor antagonists can promote liver regeneration, neither confers both benefits at the same time. Consequently, it may be of clinical interest to apply both treatments simultaneously.
Incidence of prolonged length of stay after orthotopic liver transplantation and its influence on outcomes
Authors: Smith Jenny O. , Shiffman Mitchell L. , Behnke Martha , Stravitz Todd R. , Luketic Velimir A. , Sanyal Arun J. , Heuman Doug M. , Fisher Robert A. , Cotterell Adrian H. , Maluf Daniel G. , Posner Marc P. , Sterling Richard K.
Published: February 2009

Orthotopic liver transplantation (OLT) is the only effective treatment for end-stage liver disease. Although most patients do well and are discharged promptly, some require prolonged length of stay (PLOS). The prevalence of PLOS, associated factors, and their impact on survival are not well defined. We reviewed our adult OLT database for patients who survived > 30 days. PLOS was defined as hospitalization > 30 days following OLT. Of 521 OLT recipients, 68 (13%) had PLOS with a median duration of 50 days versus only 10 days for patients discharged within 30 days. Significant differences in pre-OLT variables between patients with and without PLOS included the mean wait list time (P = 0.001), hospitalization at the time of OLT (P = 0.001), and prior OLT (P = 0.041). Factors independently associated with PLOS included intensive care unit status at the time of OLT [odds ratio (OR), 4; 95% confidence interval (CI), 1.6-10.4], OLT prior to Model for End-Stage Liver Disease implementation (OR, 2.27; 95% CI, 1.04-5.26), in-hospital post-OLT bacterial infection (OR, 9.34; 95% CI, 4.65-18.86), gastrointestinal bleeding (OR, 4.34; 95% CI, 1.4-14.08), renal failure (OR, 10.86; 95% CI, 5.07-23.25), and allograft rejection (OR, 3.7; 95% CI, 1.23-11.11). One-year graft survival and patient survival were significantly less in those with PLOS (for both, P < 0.0001). Among PLOS patients, factors independently associated with increased 1-year mortality were donor age (OR, 1.07; 95% CI, 1.009-1.13), primary diagnosis of hepatitis C virus (OR, 6.89; 95% CI, 1.40-34.48), in-hospital post-OLT bacterial infection (OR, 13.3; 95% CI, 2.11-83.33), and cardiac complications (OR, 20.4; 95% CI, 1.51-250; c-statistic for the model, 0.85). In conclusion, PLOS following OLT is associated with a significant decrease in survival despite a marked increase in cost and resource utilization. Efforts to modify those factors that contribute to PLOS may reduce this event, improve survival, and reduce OLT-associated costs.
Longer Waiting Times for Obese Liver Transplant Patients
Authors: Perkins James D.
Published: February 2009

Abstract

Objective:

To quantify the independent association between obesity and access to liver transplantation.

Background:

Obesity is associated with higher complication rates, longer hospitalization, and worse survival after liver transplantation. Nevertheless, transplantation provides survival benefit to patients with end-stage liver disease, regardless of body mass index (BMI). We hypothesized that, despite survival benefit, providers were reluctant to transplant obese patients because of the inherent difficulty of these cases and their inferior outcomes. Our goal was to quantify the independent association between BMI and waiting time for orthotopic liver transplantation as a surrogate marker for this reluctance.

Methods:

We studied 29,136 wait-list candidates in the model for end-stage liver disease (MELD) era, categorized as severely obese (BMI 35-40), morbidly obese (BMI 40-60), and reference (BMI 18.5-35). All models were adjusted for factors relevant to the allocation system, factors possibly influencing access to healthcare, and factors biologically related to disease progression and outcomes.

Results:

The odds of receiving a MELD exception were 30% lower in severely obese and 38% lower in morbidly obese patients. Similarly, the likelihoods of being turned down for an organ were 10% and 16% higher, and the rates of being transplanted were 11% and 29% lower in severely obese and morbidly obese patients, respectively.

Conclusions:

Current practice seems to indicate a reluctance to transplant obese patients. If indeed as a community we feel that liver allografts should not be distributed to patients with excessive postoperative risk, we should consider expressing this as a formal change to our allocation policy rather than through informal practice patterns.
Macromol. Chem. Phys. 5/2009
Authors: Bellas Vasilios , Rehahn Matthias
Published: February 2009

Cover: Chemoselective stepwise coupling between living polymers and a heterobifunctional linking agent renders feasible the synthesis of block copolymers that are not accessible by sequential monomer addition. This facile and efficient synthetic tool resembles the versatility of a Swiss‐army knife, being a powerful strategy for accessing well‐defined block copolymers. Further details can be found in the article by V. Bellas, M. Rehahn on page 320.
Laser ablation‐inductively coupled plasma mass spectrometry in archaeometric research
Authors: Resano Martín , García‐Ruiz Esperanza , Vanhaecke Frank
Published: February 2009

Laser ablation‐inductively coupled plasma mass spectrometry (LA‐ICPMS) is a solid sampling technique in continuous expansion in all types of research fields in which direct multi‐elemental or isotopic analysis is required. In particular, this technique shows unique characteristics that made its use recommended in many archaeometric applications, where valuable solid artifacts are often the target samples, because it offers flexibility to achieve spatially resolved information with high detection power and a wide linear range, in a fast and straightforward way, and with minimal sample damage. The current review provides a systematic survey of publications that reported the use of LA‐ICPMS in an archaeological context, highlights its main capabilities and limitations and discusses the most relevant parameters that influence the performance of this technique for this type of application. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 29:55–78, 2010
Questionnaire‐based assessment of pelvic organ dysfunction in multiple system atrophy
Authors: Yamamoto Tatsuya , Sakakibara Ryuji , Uchiyama Tomoyuki , Liu Zhi , Ito Takashi , Awa Yusuke , Yamanishi Tomonori , Hattori Takamichi
Published: February 2009

Multiple system atrophy (MSA) is a neurodegenerative disease characterized clinically by any combination of autonomic, cerebellar, and extrapyramidal symptoms. Autonomic symptoms are usually severe, and urinary symptoms are one of the cardinal features of MSA. Bowel dysfunction and sexual dysfunction are also common in MSA. Quality of life (QOL) in patients with MSA is severely impaired by the presence of pelvic organ dysfunction. Therefore, we aimed to examine the prevalence of pelvic organ dysfunction in patients with MSA. We recruited 256 patients with MSA seen at our neurology clinic. The mean age was 62 years. The control group comprised 158 individuals, and the mean age was 52 years. We administered a questionnaire on pelvic organ dysfunction to the MSA and control groups. The questionnaire had sections focusing on the bladder, bowel, and sexual function. Dysfunction, as described in the responses, was evaluated as normal, mild (>once a month), moderate (>once a week), or severe (>once a day). The Mann‐Whitney's U‐test was used for statistical analysis. When compared with the control group, the prevalence of pelvic organ dysfunction in the MSA group was significantly higher for urinary storage and voiding dysfunction, bowel dysfunction, and sexual dysfunction. QOL in the MSA group was therefore significantly impaired because of urinary dysfunction (70%, 76%), bowel dysfunction (40% of the men), and sexual dysfunction (26%, 45%). Pelvic organ dysfunction is common in MSA, and QOL is severely impaired in patients with MSA. © 2009 Movement Disorder Society
Description of a family with a novel progressive myoclonus epilepsy and cognitive impairment
Authors: Ferlazzo Edoardo , Italiano Domenico , An Isabelle , Calarese Tiziana , Laguitton Virginie , Bramanti Placido , Di Bella Paolo , Genton Pierre
Published: February 2009

We report a family of Algerian origin presenting an unusual, severe form of progressive myoclonus epilepsy characterized by myoclonus, generalized tonic‐clonic seizures and moderate to severe cognitive impairment, with probable autosomal recessive inheritance. Disease onset was between 6 and 16 years of age. The diagnosis of Unverricht‐Lundborg disease and all other known causes of progressive myoclonus epilepsies were excluded by specific laboratory tests and molecular analysis. © 2009 Movement Disorder Society
Deterministic chaos in a model of discrete manufacturing
Authors: Bartholdi John J. , Eisenstein Donald D. , Lim Yun Fong
Published: February 2009

A natural extension of the bucket brigade model of manufacturing is capable of chaotic behavior in which the product intercompletion times are, in effect, random, even though the model is completely deterministic. This is, we believe, the first proven instance of chaos in discrete manufacturing. Chaotic behavior represents a new challenge to the traditional tools of engineering management to reduce variability in production lines. Fortunately, if configured correctly, a bucket brigade assembly line can avoid such pathologies. © 2009 Wiley Periodicals, Inc. Naval Research Logistics 2009
What you should know about approximate dynamic programming
Authors: Powell Warren B.
Published: February 2009

Approximate dynamic programming (ADP) is a broad umbrella for a modeling and algorithmic strategy for solving problems that are sometimes large and complex, and are usually (but not always) stochastic. It is most often presented as a method for overcoming the classic curse of dimensionality that is well‐known to plague the use of Bellman's equation. For many problems, there are actually up to three curses of dimensionality. But the richer message of approximate dynamic programming is learning what to learn, and how to learn it, to make better decisions over time. This article provides a brief review of approximate dynamic programming, without intending to be a complete tutorial. Instead, our goal is to provide a broader perspective of ADP and how it should be approached from the perspective of different problem classes. © 2009 Wiley Periodicals, Inc. Naval Research Logistics 2009
Analysis of fluid‐structure interaction in low pressure MEMS by Integral Equations
Authors: Frangi Attilio
Published: February 2009

The evaluation of gas dissipation occurring in inertial polysilicon MEMS is addressed focusing the attention on the free–molecule flow. In this regime, which is very often of interest for industrial applications, collisions between molecules can be neglected and the momentum transfer to the moving shuttle can be easily computed. Since the surfaces of silicon MEMS are generally very rough, a complete diffusion model is adopted to describe the wall–molecule interaction. A Boundary Integral Equation approach is proposed and it is shown that the introduction of the key assumption of small perturbations is crucial in the development of a robust and fast numerical tool. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of gradient based algorithms for robust shape optimization of a tensile test specimen
Authors: Abel Bengt , Schumacher Axel , Bartsch Marion
Published: February 2009

In case of technical applications such as automotive or aeronautic part optimization, uncertainties in design variables and other parameters have to be taken into account. Especially, scattering of material properties and mechanical loads have large influences on the component behavior.

Due to the difficulty in calculating of sensitivities, usually stochastic algorithms are used for robust and reliability optimization. That entails a large number of function calls and long computation time. Therefore, the stochastic responses with expectation value and variances will be approximated by response surfaces in this contribution. Based on the practical example of a tensile test specimen a deterministic optimization and optimization under uncertainties will be done. The results of the different optimizations will be compared and the influence of the uncertainties will be shown and discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New adaptive mixed finite element method (AMFEM)
Authors: Carstensen Carsten , Rabus Hella
Published: February 2009

The need to develop reliable and efficient adaptive algorithms using mixed finite element methods arises from various applications in fluid dynamics and computational continuum mechanics. In order to save degrees of freedom, not all but just some selected set of finite element domains are refined and hence the fundamental question of convergence requires a new mathematical argument as well as the question of optimality.

We will present a new adaptive algorithm for mixed finite element methods to solve the model Poisson problem, for which optimal convergence can be proved. The a posteriori error control of mixed finite element methods dates back to Alonso (1996) Error estimators for a mixed method. and Carstensen (1997) A posteriori error estimate for the mixed finite element method. The error reduction and convergence for adaptive mixed finite element methods has already been proven by Carstensen and Hoppe (2006) Error Reduction and Convergence for an Adaptive Mixed Finite Element Method, Convergence analysis of an adaptive nonconforming finite element methods.

Recently, Chen, Holst and Xu (2008) Convergence and Optimality of Adaptive Mixed Finite Element Methods. presented convergence and optimality for adaptive mixed finite element methods following arguments of Rob Stevenson for the conforming finite element method. Their algorithm reduces oscillations, before applying and a standard adaptive algorithm based on usual error estimation. The proposed algorithm does this in a natural way, by switching between the reduction of either the estimated error or oscillations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
hp‐Adaptive Finite Element Methods for Variational Inequalities
Authors: Schröder Andreas
Published: February 2009

In this work, we combine an hp–adaptive strategy with a posteriori error estimates for variational inequalities, which are given by contact problems. The a posteriori error estimates are obtained using a general approach based on the saddle point formulation of contact problems and making use of a yposteriori error estimates for variational equations. Error estimates are presented for obstacle problems and Signorini problems with friction.

Numerical experiments confirm the reliability of the error estimates for finite elements of higher order. The use of the hp–adaptive strategy leads to meshes with the same characteristics as geometric meshes and to exponential convergence. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear Model Order Reduction in Nanoelectronics: Combination of POD and TPWL
Authors: Bechtold T. , Striebel M. , Mohaghegh K. , ter Maten E. J. W.
Published: February 2009

In this paper we demonstrate model order reduction of a nonlinear academic model of an inverter chain. Two reduction methods, which are suitable for nonlinear differential algebraic equation systems are combined, the trajectory piecewise linear approach and the proper orthogonal decomposition. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamical iteration schemes for coupled simulation in nanoelectronics
Authors: Culpo Massimiliano , de Falco Carlo
Published: February 2009

In this paper we present an approach to coupled electro–thermal circuit simulation. More precisely we derive from the heat diffusion PDE a thermal element model and we show how it can be included in a standard SPICE–like circuit simulator without significant modifications to the solver structure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polynomial Chaos for Analysing Periodic Processes of Differential Algebraic Equations with Random Parameters
Authors: Pulch Roland
Published: February 2009

Mathematical models of dynamical systems typically include technical parameters. Assuming an uncertainty, some parameters are replaced by random variables and the solution of the time–dependent system becomes a stochastic process. We consider forced oscillators, which are modelled by systems of differential algebraic equations. Consequently, periodic boundary conditions are imposed on the system. We apply the technique of the generalised polynomial chaos to resolve the stochastic model. Numerical simulations based on the electric circuit of a transistor amplifier are presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental investigation of a moored floating system
Authors: Beyer Daniel , Ellermann Katrin
Published: February 2009

Floating structures are generally excited by a more or less irregular sea state. Therefore the structure undergoes a nonlinear dynamical behaviour which results from hydrodynamic effects or the kinematic coupling of different components. The motions of these structures have been analysed intensively with numerical techniques which predict a wide range of nonlinear effects. On the other hand, experiments are still important when it comes to verifying these theoretical findings. Investigating such a floating structure experimentally requires a complex setup: A wave generator needs to be driven in an appropriate way to yield waves with the required characteristics at the structure. The structure itself is usually designed similar to a real–world system and it has to allow for a comparison with numerical analyses. Sensors which measure the tracks of the individual components not only have to reach a prescribed precision but also need to ensure that the motion is not perturbed as a result of the measurements. Lastly, unwanted disturbances have to be avoided. For experiments in a wave tank this includes that reflections have to be minimized. This talk addresses the development of an experimental setup for the investigation of a floating structure. It highlights components which are found to be critical for the obtained accuracy and proposes techniques to reduce experimental errors. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation einfacher reibungsbehafteter Stoßkontakte
Authors: Fritz Felix , Friedrich Carl‐Christoph , Seemann Wolfgang
Published: February 2009

Um die Eignung des kommerziellen Mehrkörperdynamikprogramms MSC/ADAMS zur Simulation von reibungsbehafteten Stoßkontakten zu untersuchen, werden einfache Schusssituationen beim Tischfußball simuliert und die Ergebnisse mit denen analytischer Stoßmodelle verglichen. Als Testsituation dient das experimentell betrachtete Phänomen, wann der Ball aus dem Tor zurückspringt, obwohl die Prallplatte getroffen wurde. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modellierung der Pfahlrammung mit der Discrete Element Method
Authors: Heesen E. , Kreuzer E.
Published: February 2009

Bei der Pfahlinstallation wird der Eindringwiderstand aus dem Bruch– und Verformungsverhalten des umgebenden Bodens sowie der Kraftübertragung an der Grenzschicht von Pfahl zu Boden bestimmt. In der Grenzschicht zwischen Pfahl und Boden sind die Effekte von großen Verformungen, Scherbandbildung, Kornrotationen und Strukturänderungen besonders stark ausgeprägt, so dass in diesem Bereich eine Kontinuumsmodellierung an ihre Grenzen stößt, während hier die Stärken der Discrete Element Method (DEM) zum Tragen kommen. In der DEM werden Böden als Granulat betrachtet, das aus einem System einzelner Partikel besteht, die über Kontaktkräfte miteinander in Wechselwirkung stehen und sich gegeneinander verschieben können. In dem hier verwendeten zweidimensionalen Modell werden die Partikel als konvexe, unregelmäßige Polygone modelliert. Die DEM ist in der Lage, durch die Anwendung einfacher mechanischer Gesetze auf der Ebene der Kornkontakte das komplexe Bodenverhalten zu erfassen. Als Kontaktgesetz wird die Formulierung nach Tillemans und Herrmann [1] verwendet. Die Bewegungsgleichungen werden mit Hilfe des in der DEM üblichen Predictor–Corrector–Verfahrens fünfter Ordnung nach Gear ausgewertet, das für die Berechnung von kurz–reichweitigen Kräften mit steilen Gradienten besonders geeignet ist. Untersucht wird die Bodenmechanik im Nahfeld der Pfahlinstallation, das Fernfeld wird nicht modelliert. Es wird eine Randbedingung vorgestellt, die das Verhalten der Fernfelds adäquat wiedergibt. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical integration of differential‐algebraic equations with mixed holonomic and control constraints
Authors: Quasem Mahmud , Uhlar Stefan , Betsch Peter
Published: February 2009

The present work aims at the incorporation of control (or servo) constraints into finite–dimensional mechanical systems subject to holonomic constraints. In particular, we focus on underactuated systems, defined as systems in which the number of degrees of freedom exceeds the number of inputs. The corresponding equations of motion can be written in the form of differential–algebraic equations (DAEs) with a mixed set of holonomic and control constraints. Apart from closed–loop multibody systems, the present formulation accommodates the so–called rotationless formulation of multibody dynamics. To this end, we apply a specific projection method to the DAEs in terms of redundant coordinates. A similar projection approach has been previously developed in the framework of generalized coordinates by Blajer & Kołodziejczyk [1]. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Statistical investigation of the nonlinear dynamical behavior of offshore structures
Authors: Reimers Jürgen , Ellermann Katrin
Published: February 2009

The increasing amount of reports concerning damages of ships, structures and loss of cargo due to wave structure interaction demand the development of systems to predict critical situations in the offshore environment. Within the last years, research has been done to predict encounter with critical wave or wave groups such as “rogue waves” or the so–called “three sisters”. The aim of such research is to develop programs that predict dangerous incidents and possibly alert the crew in time. The dangers of such extreme wave situations are severe, but occurrence of them is rather rare. Additionally and more often, structures are endangered because of fluid–structure–interaction leading to critical dynamical system behaviour in a wave environment that shows no extreme wave heights. The severeness of these incidents then depends on the experience and correctness of decision concerning the evasive actions of the master and his crew. Taking nonlinear effects into account, the statistical investigation of structures in waves shows critical behaviour of ships and structures without the absolute necessity of heavy sea conditions or the occurrence of dangerous sea phenomena. This paper describes the development of a program that uses a Monte–Carlo–Simulation technique based on a common panel–method for the creation of added masses and added dampings to predict the behaviour of the structure in several wave conditions. It shows possible ways to prevent the occurrence using similar early warning systems to those in development for critical wavegroups. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Geometrically exact shells in a flexible multibody framework
Authors: Sänger Nicolas , Betsch Peter
Published: February 2009

The present work deals with the extension of contemporary finite element methods for nonlinear structural dynamics to the realm of flexible multibody dynamics. In particular, we aim at the incorporation of geometrically exact shell formulations into a multibody framework. Geometrically exact shell formulations are capable of dealing with finite deformation problems. In particular we focus on (i) a finite element discretization in space which inherits the frame–indifference of the nonlinear strain measures from the underlying continuous shell formulation, and (ii) a discretization in time which leads to an energy and momentum conserving scheme or an energy decaying variant thereof. In nonlinear structural dynamics energy–momentum schemes have proven to be well–suited for the stable numerical integration of large deformation problems.

We show that semi–discrete formulations emanating from the finite element discretization of geometrically exact shell theories can be regarded as discrete mechanical systems subject to holonomic constraints. Accordingly, the corresponding equations of motion can be written as differential–algebraic equations (DAEs) with index three. In particular, this viewpoint fits perfectly well into the framework of a rotationless description of rigid bodies [1] and geometrically exact beams [2]. Thus the DAEs provide a uniform framework for flexible multibody systems. Moreover, the DAEs turn out to be beneficial to the design of energy–momentum schemes [3–5]. Indeed our shell formulation can be shown to be equivalent to the previous work by Simo & Tarnow [6]. The newly established DAE framework facilitates the use of geometrically exact shells in flexible multibody dynamics. Representative numerical examples will demonstrate the capability of the proposed methodology. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical integration of rigid body dynamics in terms of quaternions
Authors: Siebert Ralf , Betsch Peter
Published: February 2009

Unit–quaternions (or Euler parameter) are known to be well–suited for the singularity–free parametrization of finite rotations. Despite of this advantage, unit quaternions were rarely used to formulate the equations of motion (exceptions are the works by Nikravesh [1] and Haug [2]). This might be related to the fact, that the unit–quaternions are redundant, which requires the use of algebraic constraints in the equations of motion. Nowadays robust energy consistent integrators are available for the numerical solution of these differential–algebraic equations (DAEs). In the present work a mechanical integrator for the quaternions will be derived. This will be done by a size–reduction from the director formulation of the equations of motion, which also has the form of DAEs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A uniform discretization approach to flexible multibody systems
Authors: Uhlar Stefan , Betsch Peter
Published: February 2009

The present contribution deals with a unified approach to the discretization of flexible multibody systems. We present a rotationless description of rigid body motions, augmented by the incorporation of additional rotational coordinates, as presented in [1,2]. Accordingly, the motion of rigid bodies is governed by differential–algebraic equations (DAEs) which are amenable to the design of energy–momentum conserving integration schemes. The comparatively large number of unknowns due to the presence of redundant coordinates and Lagrange multipliers can be reduced by applying specific reduction techniques, such as the discrete null space method [3].

In nonlinear elastodynamics, conserving schemes have been under investigation for several years. Recent works [4,5] turn out to be especially well suited for accurate and robust long term simulations. The underlying finite element discretization in space makes possible the use of arbitrary constitutive laws.

In essence, the present approach leads to a uniform algorithmic treatment of translations and rotations which turns out to be especially beneficial to the simulation of multibody systems. Moreover, the underlying DAE structure of the discrete equations of motion facilitates the straightforward connection of flexible and rigid components belonging to a specific multibody system. In addition to that, the design of conserving schemes can be accomplished easily. Representative numerical examples will demonstrate the advantageous behavior of the proposed uniform discretization approach to flexible multibody systems. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Decentralised Control Design of Lateral and Vertical Vehicle Dynamics using Passivity
Authors: Villegas Carlos , Corless Martin , Shorten Robert , Readman Mark , Solmaz Selim
Published: February 2009

In this paper, we present a novel methodology to design block–diagonal stable decentralised controllers based on the Kalman–Yakubovich–Popov lemma. The approach yields closed–loop systems that are robust with respect to parameter uncertainty and structural perturbations. We demonstrate the methodology by designing controllers for the lateral and vertical subsystems of a vehicle emulator; namely, a test vehicle that can mimic the behaviour of a wide range of vehicles. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)