bluuebunny/crossref_metadata_2025 huggingface dataset:
Collapse of Reinforced Concrete Column by Vehicle Impact
Authors: Tsang Hing‐Ho , Lam Nelson T. K.
Published: June 2008

Abstract:  Walk‐up flats are typically supported by slender columns on the ground floor forming a soft storey. The column slenderness ratio can be in the order of 6–9. Some of these buildings are right next to busy streets and hence continuously exposed to the potential hazard of a vehicle impacting on a column in an accident. In the early part of this study, the ultimate energy absorption capacity of a reinforced concrete column is compared to the kinetic energy embodied in the moving vehicle. The energy‐absorption capacity is calculated from the force‐displacement curve of the column as determined from a nonlinear static (push‐over) analysis. The ultimate displacement of the column is defined at the point when the column fails to continue carrying the full gravitational loading. Results obtained from the nonlinear static analysis have been evaluated by computer simulations of the dynamic behavior of the column following the impact. Limitations in the static analysis procedure have been demonstrated. The effects of strain rate have been discussed and the sensitivity of the result to changes in the velocity function and stiffness of the impacting vehicle has also been studied.
Dynamic Response of a Rollover Protective Structure
Authors: Thambiratnam David P. , Clark Brian J. , Perera Nimal J.
Published: June 2008

Abstract:  Roll Over Protective Structures (ROPS) are safety devices fitted to heavy vehicles to provide protection to the operator during an accidental roll over. At present, ROPS design standards require full‐scale destructive testing that can be expensive, time consuming, and unsuitable for small companies. More economical analytical methods are not permitted due to a lack of understanding of post yield behavior and the energy absorption capacity of ROPS. To address this, a comprehensive research project was undertaken to investigate ROPS behavior using analytical techniques supported by experiments. This article presents the dynamic impact analysis of a bulldozer ROPS using calibrated finite element models. Results indicate that (1) ROPS posts have significant influence on the energy‐absorbing capacity, (2) dynamic amplifications in energy could be up to 25%, (3) stiffer ROPS cause high peak decelerations that may be detrimental to the operator, and (4) analytical techniques may be used for evaluating ROPS performance.
Traffic Barriers under Vehicular Impact: From Computer Simulation to Design Guidelines
Authors: Ulker M. B. C. , Rahman M. S. , Zhen R. , Mirmiran A.
Published: June 2008

Abstract:  In this study, the problem of vehicular impact on a portable concrete barrier (PCB) is investigated. An available crash test is modeled and the impact response was simulated through a finite element (FE) model. On the basis of insight gained through this detailed FE analysis, a simpler rigid body model is then used to perform a comprehensive study of the barrier response under vehicular impact. The results from FE simulation and the rigid body model are found to be consistent with each other and in good agreement with the full‐scale crash test. On the basis of results from a series of simpler analyses, a set of charts for assessing the barrier displacement and related variables are developed for the purpose of design.
OVEREDUCATION AND COLLEGE MAJOR: EXPANDING THE DEFINITION OF MISMATCH BETWEEN SCHOOLING AND JOBS*
Authors: ROBST JOHN
Published: June 2008

In this paper we expand the concept of educational mismatch to incorporate both the quantity and type of schooling into a measure of the distance between schooling and work. The wage effects increase as the distance between schooling and work increases, suggesting heterogeneity of both schooling and workers among the overeducated. The transferability of skills between college major and occupation, as well as the reason for accepting the position, is also examined.
Serological response to hepatitis B virus vaccine in HIV‐infected children in Tanzania
Authors: Pippi F , Bracciale L , Stolzuoli L , Giaccherini R , Montomoli E , Gentile C , Filetti S , De Luca A , Cellesi C
Published: June 2008

Background

HIV‐infected children have a lower seroconversion rate to hepatitis B virus (HBV) immunization than healthy children. Previous studies have produced conflicting results on CD4 cell counts as predictors of vaccine response. No study has evaluated the response rate to HBV vaccination in HIV‐infected children receiving highly active antiretroviral therapy (HAART). Our aim was to vaccinate HIV‐infected children living in a close community and to investigate the anamnestic response rate after vaccination with its predictors.

Methods

Eighty‐four HIV‐positive children aged 1–10 years who were negative for antibodies to the HBV core antigen (anti‐HBc) completed immunization with three doses of 5 μg HBVAXPRO (Aventis, Milan, Italy). Quantitative testing for antibodies to the HBV surface antigen (anti‐HBs) was performed: a seroprotective titre was defined as anti‐HBs>10 mUI/mL.

Results

After the vaccination, the anti‐HBs seroconversion rate was 59.5%. It was higher in individuals in Centers for Disease Control and Prevention (CDC) immune category 1 than in those in CDC categories 2 and 3. Seroconversion was found in 70.8% of HAART‐treated and 44.4% of treatment‐naïve children. In multivariable models, HAART use and absolute CD4 cell counts were independently associated with probability of seroconversion and with higher anti‐HBs titres.

Conclusions

We found a higher seroconversion rate compared with previous studies in HIV‐infected children. In children who are candidates to receive antiretroviral therapy, it may be advisable to defer HBV vaccination until after treatment initiation.
Abnormal thyroid function in older men with or at risk for HIV infection*
Authors: Wiener M , Lo Y , Klein RS
Published: June 2008

Objectives

The aim of the study was to evaluate the prevalence of and factors associated with abnormal thyroid function in older men with or at risk for HIV infection.

Methods

A cross‐sectional analysis of 636 men ≥49 years old was carried out using data obtained from interviews, from measurements of body mass index (BMI), HIV‐1 serology and viral load, CD4 cell count, hepatitis C virus (HCV) assays, thyroid‐stimulating hormone (TSH) and free thyroid hormone levels.

Results

Participants were 54% black, 57% overweight/obese, 57% HIV seropositive, and 72% HCV seropositive; 38% reported recent cocaine or heroin use. Decreased TSH was found in 56 men (8.8%) and raised TSH in 23 men (3.6%). Only three men had abnormal free thyroxine levels.

Conclusions

Abnormal TSH levels were noted in 12.4% of older men with or at risk for HIV infection, but nearly all reflected subclinical hyperthyroidism or subclinical hypothyroidism.
MxA protein – an interferon beta biomarker in primary progressive multiple sclerosis patients
Authors: Millonig A. , Dressel A. , Bahner D. , Bitsch A. , Bogumil T. , Elitok E. , Kitze B. , Tumani H. , Weber F. , Gneiss C. , Deisenhammer F.
Published: June 2008

Background and purpose:  Interferon beta (IFNβ) preparations have some effect on the progressive phase of multiple sclerosis (MS). This limited effect might be partially because of a certain number of IFNβ non‐responders. Myxovirus resistance protein A (MxA) – a marker of IFNβ bioactivity – was correlated with the clinical response during an uncontrolled trial, investigating the safety of IFNβ‐1b in primary progressive (PPMS) patients.

Methods:  Twenty PPMS were treated with IFNβ‐1b (s.c.) for 1 year. Blood samples were taken before and 1, 2, 3, 6, 9, 12, and 15 months after treatment initiation and MxA protein levels were measured. Patients were clinically evaluated by EDSS and the more sensitive Incapacity Status Scale (ISS) and stratified in a stable and a progressing group.

Results:  Using ISS criteria, 11 patients remained stable and nine patients progressed during treatment. The mean area under the curve of log MxA levels during treatment were significantly higher in stable than in progressing patients (10.87 vs. 5.99; P = 0.002).

Conclusion:  A good biological response to IFNβ might be associated with a better clinical effect of this drug and could be helpful in future clinical studies for early identification of treatment responders.
Arterial stiffness, metabolic syndrome and inflammation amongst Asian ischaemic stroke patients
Authors: De Silva D. A. , Woon F.‐P. , Gan H.‐Y. , Cameron J. , Kingwell B. , Koh T.‐H. , Chen C. , Chang H.‐M. , Wong M.‐C.
Published: June 2008

Background and purpose:  Arterial stiffness and metabolic syndrome (MetS) are risk factors for ischaemic stroke. We studied the association of arterial stiffness, measured by carotid–femoral pulse wave velocity (PWV) and MetS amongst ischaemic stroke patients. We also investigated the role of inflammation measured by serum erythrocyte sedimentation rate (ESR) in the metabolic syndrome–arterial stiffness relationship.

Methods:  Amongst the 229 prospectively recruited acute ischaemic stroke patients, we measured carotid–femoral PWV using applanation tonometry and the inflammatory marker serum ESR.

Results:  Carotid–femoral PWV was significantly higher amongst patients with MetS (P = 0.002), increased waist circumference (P = 0.010), raised blood pressure (P < 0.001) and abnormal glycemia (P = 0.002); and increased with the number of MetS components (P = 0.002). In a sub‐group of 199 patients, carotid–femoral PWV was significantly correlated with serum ESR (P < 0.001). In multivariate regression analysis including serum ESR and MetS as variables, carotid–femoral PWV was independently associated with higher ESR (P = 0.002) but not with MetS (P = 0.139).

Conclusions:  Arterial stiffness is significantly associated with MetS amongst ischaemic stroke patients, and inflammation appears to be involved in this relationship.
Functional interactions of APP with the apoE receptor family
Authors: Hoe Hyang‐Sook , William Rebeck George
Published: June 2008

The β‐amyloid precursor protein (APP) is central to the pathogenesis of Alzheimer’s disease, but its normal functions in the brain are poorly understood. A number of APP‐interacting proteins have been identified: intracellularly, APP interacts with adaptor proteins through its conserved NPXY domain; extracellularly, APP interacts with a component of the extracellular matrix, F‐spondin. Interestingly, many of these APP‐interacting proteins also interact with the family of receptors for apolipoprotein E (apoE), the Alzheimer’s disease risk factor. apoE receptors also share with APP the fact that they are cleaved by the same secretase activities. apoE receptors are shed from the cell surface, a cleavage that is regulated by receptor‐ligand interactions, and C‐terminal fragments of apoE receptors are cleaved by γ‐secretase. Functionally, both APP and apoE receptors affect neuronal migration and synapse formation in the brain. This review summarizes these numerous interactions between APP and apoE receptors, which provide clues about the normal functions of APP.
Inhibition of TASK1‐like channels by muscarinic receptor stimulation in rat adrenal medullary cells
Authors: Inoue Masumi , Harada Keita , Matsuoka Hidetada , Sata Takeyoshi , Warashina Akira
Published: June 2008

The muscarinic receptor is known to be involved in the acetylcholine‐induced secretion of catecholamines in the adrenal medulla (AM) cells of various mammals. The ionic mechanisms, however, have not been elucidated yet. Thus, we investigated the issue in acutely isolated rat AM cells with the perforated patch clamp method. Bath application of 30 μM muscarine induced depolarization with the consequent generation of action potentials or an inward current at negative membrane potentials. The muscarine‐sensitive current instantaneously changed in amplitude upon application of command pulses without a time‐dependent component, altered the polarity as a K+‐electrode, and showed rectification of the Goldman‐Hodgkin‐Katz (GHK) type. The whole‐cell current at −20 mV was inhibited by external H+ions with a concentration responsible for half inhibition of pH 7.09 and muscarine failed to induce a further inward current during exposure to a saline in which pH decreased to 6.5. A similar occlusion occurred in secretion when pH in muscarine‐containing saline decreased to 6.6. RT‐PCR, immunoblotting, and immunocytochemistry suggested that rat AM cells mainly express the TASK1 channel. This TASK channel in AM cells may directly sense a decrease in blood pH, which occurs during exercise. The muscarine action was mimicked by oxotremorine–methiodide, but not by oxotremorine. The present results indicate that activation of muscarinic receptors or a decrease in external pH in the rat AM cell induces secretion through the inhibition of TASK1‐like channels.
Reduced Ejection Fraction, Sudden Cardiac Death, and Heart Failure Death in the Mode Selection Trial (MOST): Implications for Device Selection in Elderly Patients with Sinus Node Disease
Authors: SWEENEY MICHAEL O , HELLKAMP ANNE S , ELLENBOGEN KENNETH A , LAMAS GERVASIO A
Published: June 2008

Background:The purpose of this study was to describe the incidence and predictors of sudden cardiac death (SCD) and heart failure (HF) death, and coexisting indications for ICDs and CRT, in patients with sinus node disease (SND) treated with pacemakers.

Methods and Results:Baseline variables were used to predict SCD and HF death among 1,135 patients in the Mode Selection Trial, a 6‐year trial of pacing mode in SND. There were 73 deaths among 177 patients with EF ≤ 35% (41.2%), 46/156 (29.5%) with EF 36–49%, and 147/802(18.3%) with EF ≥ 50%. SCD accounted for 21.9%, 23.9%, and 14.3% of deaths with EF ≤ 35%, 36–49%, and ≥ 50%. HF deaths accounted for 23.3%, 19.6%, and 3.4% of deaths with EF ≤ 35%, 36‐49%, and ≥ 50%. EF ≤ 35% predicted SCD (hazard ratio [HR] 3.68, 95% confidence interval [CI] 1.72‐7.89, P = 0.002) and HF death (HR 10.17, 95% CI 3.35, 30.82, P = 0.001). Four‐year SCD rate with EF ≤ 35% was 15.5% (3.9% annually).

Nearly one‐fifth of patients qualified for ICDs (EF ≤ 35%) and half of these had QRS ≥ 120 ms. However, >40% died within 33 months (4‐year noncardiac death rate ∼22%).

Conclusions:Reduced EF predicts SCD and HF death in SND treated with pacemakers. SCD rates among patients with EF ≤ 35% are similar to control arms of primary prevention ICD trials, but mortality rates are significantly higher. Whether ICDs or CRT to provide bradycardia support would prolong life in elderly patients with EF ≤ 35% and SND merits prospective investigation.
Prognostic Value of QT/RR Slope in Predicting Mortality in Patients with Congestive Heart Failure
Authors: CYGANKIEWICZ IWONA , ZAREBA WOJCIECH , VAZQUEZ RAFAEL , ALMENDRAL JESUS , BAYES‐GENIS ANTONI , FIOL MIQUEL , VALDES MARIANO , MACAYA CARLOS , GONZALEZ‐JUANATEY JOSE R. , CINCA JUAN , DE LUNA ANTONI BAYES ,   on behalf of MUSIC Investigators
Published: June 2008

Introduction: Repolarization dynamics, reflecting adaptation of QT to changing heart rate, is considered a marker of unfavorable prognosis in patients with heart diseases. We aimed to evaluate the prognostic value of QT/RR slope in predicting total mortality (TM) and sudden death (SD) in patients with congestive heart failure (CHF).

Methods and Results: In 651 sinus rhythm patients with CHF in NYHA class II–III enrolled in the MUSIC study, 24‐hour Holter monitoring was performed at enrollment to assess slope of the QTa/RR (QT apex) and QTe/RR (QTend) during the entire 24‐hour Holter recording and separately during day and night periods. Patients were followed for a median of 44 months, with the primary endpoint defined as TM and the secondary as SD. Analysis of repolarization dynamics was feasible in 542 patients (407M), mean age 63 years, 83% in NYHA class II, 49% with ischemic cardiomyopathy, with mean LVEF 37%. Mean value of QTa/RR slope was 0.172 and QTe/RR was 0.193. During the 44‐month follow‐up there were 119 deaths including 47 SD. Nonsurvivors were characterized by steeper QT/RR slopes. Increased QT/RR slopes during the daytime (>0.20 for QTa and >0.22 for QTe) were independently associated with increased TM in multivariate analysis after adjustment for clinical covariates with respective hazard ratios 1.57 and 1.58, P = 0.002. None of the dynamic repolarization parameters was associated with increased risk of SD in the entire population.

Conclusions: Abnormal repolarization dynamics reflected as increased daytime QT/RR slopes is an independent risk stratifier of all‐cause mortality in patients with chronic heart failure
Correlates of subjective and objective burden among caregivers of patients with bipolar disorder
Authors: Ostacher M. J. , Nierenberg A. A. , Iosifescu D. V. , Eidelman P. , Lund H. G. , Ametrano R. M. , Kaczynski R. , Calabrese J. , Miklowitz D. J. , Sachs G. S. , Perlick D. A. ,   the STEP‐BD Family Experience Collaborative Study Group
Published: June 2008

Objective:  We examined the relationship between mood symptoms and episodes in patients with bipolar disorder and burden reported by their primary caregivers.

Method:  Data on subjective and objective burden reported by 500 primary caregivers for 500 patients with bipolar disorder participating in the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP‐BD) were collected using semistructured interviews. Patient data were collected prospectively over 1 year. The relationship between patient course and subsequent caregiver burden was examined.

Results:  Episodes of patient depression, but not mood elevation, were associated with greater objective and subjective caregiver burden. Burden was associated with fewer patient days well over the previous year. Patient depression was associated with caregiver burden even after controlling for days well.

Conclusion:  Patient depression, after accounting for chronicity of symptoms, independently predicts caregiver burden. This study underscores the important impact of bipolar depression on those most closely involved with those whom it affects.
Objective social outcomes index (SIX): a method to summarise objective indicators of social outcomes in mental health care
Authors: Priebe S. , Watzke S. , Hansson L. , Burns T.
Published: June 2008

Objective:  No method has yet been established to summarise different objective indicators of social outcomes into one score. The study aimed to develop and test a simple, brief and meaningful index of social outcomes that can be used across a broad range of mental health studies and is potentially obtainable from routine documentation.

Method:  An index capturing employment, accommodation and living situation (range from 0 to 6; SIX) was devised and tested in three longitudinal datasets of patients with severe mental illness from Germany, Sweden and the UK.

Results:  SIX showed an almost normal distribution cross‐sectionally in all three datasets. Between 58 and 78% of patients changed scores over time. Change scores were weakly associated with change scores of symptoms, quality of life, global functioning and disability.

Conclusion:  A simple method to summarise different indicators of social outcomes provides meaningful results. It can be widely used in research and routine care.
The rat pineal gland comprises an endocannabinoid system
Authors: Koch Marco , Habazettl Iris , Dehghani Faramarz , Korf Horst‐Werner
Published: June 2008

Abstract: In the mammalian pineal gland, the rhythm in melatonin biosynthesis depends on the norepinephrine (NE)‐driven regulation of arylalkylamineN‐acetyltransferase (AANAT), the penultimate enzyme of melatonin biosynthesis. A recent study showed that phytocannabinoids like tetrahydrocannabinol reduce AANAT activity and attenuate NE‐induced melatonin biosynthesis in rat pineal glands, raising the possibility that an endocannabinoid system is present in the pineal gland. To test this hypothesis, we analyzed cannabinoid (CB) receptors and specific enzymes for endocannabinoid biosynthesis or catabolism in rat pineal glands and cultured pinealocytes. Immunohistochemical and immunoblot analyses revealed the presence of CB1 and CB2 receptor proteins, ofN‐acyl phosphatidyl ethanolamine hydrolyzing phospholipase D (NAPE‐PLD), an enzyme catalyzing endocannabinoid biosynthesis and of fatty acid amide hydrolase (FAAH), an endocannabinoid catabolizing enzyme, in pinealocytes, and in pineal sympathetic nerve fibers identified by double immunofluorescence with an antibody against tyrosine hydroxylase. The immunosignals for the CB2 receptor, NAPE‐PLD, and FAAH found in pinealocytes did not vary under a 12 hr light:12 hr dark cycle. The CB1 receptor immunoreaction in pinealocytes was significantly reduced at the end of the light phase [zeitgeber time (ZT) 12]. The immunosignal for NAPE‐PLD found in pineal sympathetic nerve fibers was reduced in the middle of the dark phase (ZT 18). Stimulation of cultured pinealocytes with NE affected neither the subcellular distribution nor the intensity of the immunosignals for the investigated CB receptors and enzymes. In summary, the pineal gland comprises indispensable compounds of the endocannabinoid system indicating that endocannabinoids may be involved in the control of pineal physiology.
The stethoscope as a vector of infectious diseases in the paediatric division
Authors: Youngster I , Berkovitch M , Heyman E , Lazarovitch Z , Goldman M
Published: June 2008

Aim: Nosocomial infections are of great concern in hospital settings, and even more so in the paediatric ward. Health professionals and their medical equipment have long been known to act as vectors of infectious diseases. This study aimed at evaluating the presence of bacterial pathogens on the stethoscopes of medical personnel in the paediatric division.

Methods: Forty‐three stethoscopes belonging to senior physicians, residents, interns and medical students at the paediatric ward were sampled. Bacterial cultures and antibiotic sensitivity testing were carried out.

Results: All but six bacterial cultures were positive (85.7%). Staphylococcal species were the most common contaminants (47.5%). One case of methicillin‐resistant Staphylococcus aureus was encountered. Gram‐negative organisms were isolated in nine different samples (21%) including one case of Acinetobacter baumannii in the neonatal intensive care unit.

Conclusion: Most stethoscopes harbour potential pathogens. The isolation of Gram‐negative organisms pose a real risk of spreading potentially serious infections, especially in the setting of intensive care departments. Apparently, the current recommendations of regular disinfection of stethoscopes are not carried out by health personnel that participated in the study.
Presenting the Sister Saints of Ely, or Using Kinship to Increase a Monastery's Status as a Cult Center
Authors: Blanton Virginia
Published: June 2008

At the time of the Norman Conquest, the monastery of Ely in Cambridgeshire was the second wealthiest in England, holding significant lands, boasting royal patrons, and housing a number of Benedictine monks. To augment its status as a cult center, the monastery developed a genealogical narrative about their founder, Æthelthryth, which included four sister saints, two nieces, and a great‐niece. This essay considers how the narrative of kinship was established, how it was maintained throughout the later medieval period, and why the monastic center felt compelled to augment the cult of Æthelthryth with the smaller cults of her sisters. This survey demonstrates not only the means by which audiences came to know the saints venerated at Ely, but it also illustrates how one might investigate the rhetorical strategies by which a monastery could develop its status as a cult center and compete with rival houses for pilgrims, money, and benefactors.
Structural Modifications of ICAM‐1 Cyclic Peptides to Improve the Activity to Inhibit Heterotypic Adhesion of T cells
Authors: Iskandarsyah  , Tejo Bimo A. , Tambunan Usman S. F. , Verkhivker Gennady , Siahaan Teruna J.
Published: June 2008

Lymphocyte function‐associated antigen‐1 (LFA‐1)/intercellular adhesion molecule‐1 (ICAM‐1) interaction plays an important role in the formation of the immunological synapse between T cells and antigen‐presenting cells. Blocking of LFA‐1/ICAM‐1 interactions has been shown to suppress the progression of autoimmune diseases. cIBR peptide (cyclo(1,12)PenPRGGSVLVTGC) inhibits ICAM‐1/LFA‐1 interaction by binding to the I‐domain of LFA‐1. To increase the bioactivity of cIBR peptide, we systemically modified the structure of the peptide by (i) replacing the Pen residue at the N‐terminus with Cys, (ii) cyclization using amide bond formation between Lys‐Glu side chains, and (iii) reducing the peptide size by eliminating the C‐terminal residue. We found that the activity of cIBR peptide was not affected by replacing Phe with Cys. Peptide cyclization by forming the Lys‐Glu amide bond also increased the activity of cIBR peptide, presumably due to the resistance of the amide bond to the reducing nature of glutathione in plasma. We also found that a reduced derivative of cIBR with eight residues (cyclo(1,8)CPRGGSVC) has a bioactivity similar to that of the larger cIBR peptides. Our findings suggest that, by systemically modifying the structure of cIBR peptide, the biological activity of these derivatives can be optimized for future use to inhibit T‐cell adhesion in in vivo models of autoimmune diseases.
Non‐song acoustic communication in migrating humpback whales (Megaptera novaeangliae)
Authors: Dunlop Rebecca A. , Cato Douglas H. , Noad Michael J.
Published: June 2008

Abstract

Humpback whales are renowned for the complex structured songs produced by males. A second, relatively understudied area of humpback acoustic communication concerns un‐patterned sounds known as “social sounds,” produced by both males and females. These include vocalizations as well as sounds produced at the surface of the water as a result of surface behaviors (e.g., breaching, pectoral slapping). This study describes a portion of the non‐song social sound repertoire of southward migrating humpbacks in Australian waters, and explores the social relevance of these sounds. On migration, humpback whales travel in social groups of varying compositions. These social groups are not stable in that humpback whales continually change group composition by splitting from, or joining with, other groups. The results of this study suggest that “breaching” and “slapping” have a communicative function. Other sounds such as “underwater blows” and “cries” were heard mainly in competitive groups while other low‐frequency sounds such as “grumbles,”“snorts,”“thwops,” and “wops” may function in intra‐ or inter‐group communication. Particular sounds (“grunts,”“groans,” and “barks”) were almost exclusive to joining pods suggesting a role in social integration. Social sounds in humpbacks may have specific social and behavioral functions relating to social group composition, and the mediation of interactions between these social groups.
Neuropsychiatric dysfunction in patients with chronic hepatitis and liver cirrhosis
Authors: Michitaka Kojiro , Tokumoto Yoshio , Uesugi Kazuhiro , Kisaka Yoshiyasu , Hirooka Masashi , Konishi Ichiro , Mashiba Toshie , Abe Masanori , Hiasa Yoichi , Matsuura Bunzo , Horiike Norio , Shoda Takaaki , Onji Morikazu
Published: June 2008

Aim:  The aim of this study is to clarify the cerebral functions in patients with chronic hepatitis (CH) as well as those with liver cirrhosis (LC).

Methods:  We studied 58 patients with CH (20 in fibrosis stage F1, 20 in F2, 18 in F3), 77 with LC (46 rated as Child–Pugh class A, 24 as B, 7 as C), and 20 healthy volunteers (HV). Computer‐aided quantitative neuropsychiatric function test systems, including eight neuropsychiatric tests were performed.

Results:  Subjects with results over the cut‐off value for healthy subjects ranged from 11.1–28.6% in CH and 19.5–36.4% in LC. The percentages with abnormality in at least one test in CH and LC were 72.4% and 80.6%, respectively, which were significantly higher than that in the HV group (35.0%) (P = 0.003, P = 0.0003, respectively). Among CH subjects, those with three or more abnormal results in the F1, F2 and F3 subgroups were 15.0%, 20.0% and 38.9%, respectively. Among LC subjects, those with three or more abnormal results in the Child–Pugh class A, B and C subgroups comprised 30.4%, 50.0% and 57.1%, respectively. The rate in the CH F3 subgroup (P = 0.011) and in all three LC subgroups (P = 0.023, P = 0.001, P = 0.002, respectively) were significantly higher than that in the HV group.

Conclusion:  The percentage of patients with neuropsychiatric function impairment was high in both LC and CH, especially in stage F3. Neuropsychiatric dysfunction may initiate in CH in a considerable number of patients.
Measures of Order in Dynamic Systems
Authors: Arasteh Davoud
Published: June 2008

The usefulness of the Lempel-Ziv complexity and the Lyapanov exponent as two metrics to characterize the dynamic patterns is studied. System output signal is mapped to a binary string and the complexity measure of the time-sequence is computed. Along with the complexity we use the Lyapunov exponent to evaluate the order and disorder in the nonlinear systems. Results from the Lempel-Ziv complexity are compared with the results from the Lyapunov exponent computation. Using these two metrics, we can distinguish the noise from chaos and order. In addition, using same metrics we study the complexity measure of the Fibonacci map as a quasiperiodic system. Our analytical and numerical results prove that for a system like Fibonacci map, complexity grows logarithmically with the evolutionary length of the data block. We conclude that the normalized Lempel-Ziv complexity measure can be used as a system classifier. This quantity turns out to be 1 for random sequences and non-zero value less than 1 for chaotic sequences. While for periodic and quasiperiodic responses as data string grows, their normalized complexity approaches zero. However, higher deceasing rate is observed for periodic responses.
A Coupled Motion of the Thermally Induced Fluid Convection and the Membrane Motion
Authors: He Xiaoling
Published: June 2008

The present study formulates a model for a coupled oscillation of the convective flow and the solid membrane vibration, which occurs in a 2D domain of a fluid cell. The convection flow is induced by the transient thermal field of the membrane at the bottom of the fluid. The heat conduction in the solid material also causes the membrane to vibrate. This flow motion deviates from the conventional Rayleigh–Benard problem in that a transient thermal field causes the convection flow instead of a constant temperature gradient. A numerical computation reveals the synchronized motion behaviors between the Lorenz-type oscillator for the convection flow and the Duffing oscillator for the membrane motion. The bifurcation conditions from the stability analysis of the model justify the steady-state attractor behaviors and the difference in behavior from the oscillators without coupling.
Vibration Control for Parametrically Excited Coupled Nonlinear Oscillators
Authors: Maccari Attilio
Published: June 2008

A complex nonlinear system under state feedback control with a time delay corresponding to two coupled nonlinear oscillators with a parametric excitation is investigated by an asymptotic perturbation method based on Fourier expansion and time rescaling. Four coupled equations for the amplitude and the phase of solutions are derived. In the system without control, phase-locked solutions with period equal to the parametric excitation period are possible only if the oscillator amplitudes are equal, but they depend on the system parameters and excitation amplitude. In many cases, the amplitudes of periodic solutions do not correspond to the technical requirements. It is demonstrated that, if the vibration control terms are added, stable periodic solutions with arbitrarily chosen amplitude and phase can be accomplished. Therefore, an effective vibration control is possible if appropriate time delay and feedback gains are chosen.
Submarine Impact With the Oseberg Jacket
Authors: Thuestad T. C. , Nielsen F. G.
Published: June 2008

The Oseberg jacket was installed at the Oseberg field in the North Sea during the summer of 1987 and the production started on December 1, 1988. On March 6, 1988, a submarine accidentally impacted with the Oseberg jacket. This paper presents results from the evaluation of the importance of the damage to the overall structural safety. A nonlinear progressive collapse analysis is applied for the safety check. The theoretical computations are verified through evaluation of strain and acceleration time series recorded during the submarine impact. The reduction in the overall structural capacity of the jacket was in the order of 10 percent. However, the local member capacity was significantly reduced and it was necessary to remove the damaged member in order to obtain the initial level of safety.
Domains of Attraction of System of Nonlinearly Coupled Ship Motions by Simple Cell Mapping
Authors: Lee W. K.
Published: June 2008

A nonlinear dissipative dynamical system can often have multiple attractors. In this case, it is important to study the global behavior of the system by determining the global domain of attraction of each attractor. In this paper we study the global behavior of a two-degree-of freedom system. The specific system examined is a system of nonlinearly coupled ship motions in regular seas. The system is described by two second-order nonlinear nonautonomous ordinary differential equations. When the frequency of the pitch mode is twice the frequency of the roll mode, and is near the encountered wave frequency, the system can have two asymptotically stable steady-state periodic solutions. The one solution has the same period as the encountered wave period and has the pitch motion only. The other solution has twice the period of the encountered wave period and has pitch and roll motions. The harmonic and second-order subharmonic solutions show up as period-1 and period-2 solutions, respectively, in a Poincare´ map. We show how the method of simple cell mapping can be used to determine the two four-dimensional domains of attraction of the two solutions in a very effective way. The results are compared with the ones obtained by direct numerical integration.
Hydrodynamic Coefficients of a Moored Semisubmersible in Waves
Authors: Chakrabarti S. K. , Cotter D. C.
Published: June 2008

The hydrodynamic coefficients of a semisubmersible undergoing slow-drift oscillation were determined through a model test. The semisubmersible model was moored in head seas, fore and aft, with linear springs which were pretensioned and never became slack during any test run. At the beginning of each test run, the vessel was held at an initial displacement from its equilibrium position and then released, and the resulting line loads were recorded. The semisubmersible was tested in still water and in regular waves. The amplitude of the waves at a given period was varied. The added mass and damping of the semisubmersible were determined from the decayed oscillation of the loads. The semisubmersible experienced both linear and nonlinear damping. The hydrodynamic coefficients obtained from the semisubmersible as functions of wave height and period are compared with those found previously on a tanker.
Computation of Wave-Induced Drift Forces Introduced by Displaced Position of Compliant Offshore Platforms
Authors: Li Y. , Kareem A.
Published: June 2008

The wave forces computed at the displaced position of offshore structures may introduce additional drift forces. This contribution is particularly significant for compliant offshore structures that are configured by design to experience large excursions under the environmental load effects, e.g., tension leg platform. In a random sea environment, this feature can be included in the time domain analysis by synthesizing drag and diffraction forces through a summation of a large number of harmonics with an appropriate phase relationship that reflects the platform displaced position. This approach is not only limited to the time domain analysis, but the superposition of a large number of trigonometric terms in such an analysis requires a considerable computational effort. This paper presents a computationally efficient procedure in both the time and frequency domains that permits inclusion of the time-dependent drift forces, introduced by the platform displacement, in terms of linear and nonlinear feedback contributions. These time-dependent feedback forces are expressed in terms of the applied wave loads by linear and quadratic transformations. It is demonstrated that the results obtained by this approach exhibit good agreement with the procedure based on the summation of trigonometric functions.
Stress Concentrations in T/Y and K Square-to-Square and Square-to-Round Tubular Joints
Authors: Soh A. K. , Soh C. K.
Published: June 2008

A parametric stress analysis of T/Y and K square-to-square and square-to-round tubular joints subjected to axial loads, in-plane and out-of-plane bending moments has been performed using the finite element technique in order to provide a sound basis for using such sections in the design of complex structures. The results of this analysis are presented as a set of 42 equations expressing the stress concentration factor as a function of the relevant geometric parameters for various loading conditions. A comparison is made between the results obtained for square-to-square and square-to-round tubular joints and those obtained for round-to-round tubular joints by other researchers. In general, the stress concentration factors obtained from round-to-round and square-to-round tubular joints are closer as compared with those of the corresponding square-to-square tubular joints. Moreover, the stress concentration factors for square-to-square tubular joints are generally lower than those of the corresponding round-to-round and square-to-round tubular joints when the joints are subject to axial loads; but the reverse is true when the joints are subject to in-plane bending moments. However, the stress concentration factors for the three types of joint are comparable when they are subject to out-of-plane bending moments.
Twin Floating Connected Models in Regular Beam Waves
Authors: Sundaravadivelu R. , Harps R. , Mahrenholtz O.
Published: June 2008

This paper presents the studies carried out on twin floating models connected alongside with hinge connection in regular beam waves of different frequencies in a wave flume. The heave, roll and sway, normalized with the wave amplitude are reported for a single box, a single half-cylinder, twin boxes and twin half-cylinders. The effect of separation distance and stiffness of the connection on the response of the twin models are also reported.
Approximation of Interference Effects in Dynamic Ice-Structure Interactions
Authors: Abul-Azm A. G. , Williams A. N.
Published: June 2008

Elastic wave theory is utilized to investigate the influence of interference effects on the dynamic forces experienced by the members of an array of rigid circular cylindrical structures, subjected to steady-state vibration while surrounded by a homogeneous, isotropic, elastic ice medium of infinite extent. Ice cracking is neglected in the analysis. Interference effects are estimated through the modified plane wave approach—an asymptotic technique which is essentially a large-spacing approximation. Numerical results for two and four-cylinder arrays indicate that interference effects may significantly alter the amplitude and phase of the reaction force experienced by the array members from that which they would each experience in isolation.
Planar Oscillatory Flow Forces at High Reynolds Numbers
Authors: Chaplin J. R.
Published: June 2008

Measurements of pressures around a circular cylinder with fine surface roughness in planar oscillatory flow reveal considerable changes in drag and inertia coefficients over the Reynolds number range 2.5 × 105 to 7.5 × 105, and at Keulegan-Carpenter numbers between 5 and 25. In most respects, these results are shown to be compatible with previous measurements in planar oscillatory flow, and with previous measurements in which the same 0.5-m-dia cylinder was tested in waves.
New Concepts, Environment and Model Testing
Authors: Gudmestad O. T.
Published: June 2008

With continued low oil prices, there is a need to develop low-cost production platforms for marginal and deep water. On the other hand, there is an increasing awareness related to safety and environmental aspects. These constraints call for a high degree of innovation and integrity. The scientists and engineers working in this climate cannot accept simplification and shortcuts and it is important that proper engineering, testing and design be carried out. It is appreciated that the management of operating companies acknowledge the importance of safe design to protect lives, the environment, and their investments.
Experimentally Determined Deformations and Stresses in Narrow-Gap and Single-U Multi-Pass Butt-Welded Pipes
Authors: Jonsson M. , Josefson B. L. , Na¨sstro¨m M.
Published: June 2008

This paper describes a study of the multi-pass butt-welding of thick-walled pipes. Two different groove shapes were used: single-U and narrow-gap grooves. Strains were measured on both the pipe outer and inner surfaces during and after welding. Residual stresses and radial deflections were measured on the outer surface after welding. Measured parameters of the two different groove shapes are compared and discussed. Residual stresses at the weld center and radial deflections in the narrow-gap pipe were somewhat larger than those in the single-U pipe. The residual stress fields of both types of groove were found to be rotationally nonsymmetrical. The experimentally obtained residual stresses and radial deflections are compared with corresponding analytical and empirical results based on methods described in the literature and with numerical results for the same pipe from a separate study. Deviations between the measurements presented in this study and published results are discussed.
Fatigue and Fracture Reliability and Maintainability of TLP Tendons
Authors: Kung C. J. , Wirsching P. H.
Published: June 2008

A tension leg platform (TLP) tendon system experiences oscillatory tensile stresses, and therefore is vulnerable to fatigue and fracture. Because design factors have significant uncertainty, a reliability analysis to quantify structural performance is appropriate. A maintenance program of periodic inspection and repair shows promise for improving system reliability and enhancing structural integrity. The performance of a TLP tendon system was simulated in order to study the relationship of design factors to system reliability. Effects on system reliability and maintenance performance (repair and replacement rates) can be studied as a function of (a) number of joints, J; (b) number of members, M; (c) inspection frequency; (d) inspection sensitivity as defined by the POD (probability of detection) curve; (e) ultimate strength; (f) repair policy; etc. The performance of an initially damaged or flawed tendon system is investigated. The reliability of a system that uses pressurized tendons to detect through-thickness cracks is studied, as is the vulnerability of the tendon system before replacement of broken tendons.
Laboratory Testing of a Flexible Boom for Ice Management
Authors: Lo̸set S. , Timco G. W.
Published: June 2008

Combatting oil spills in the Arctic is a major challenge. Drilling or producing oil or gas in the marginal ice zone (MIZ) may allow booms to be deployed upstream of an offshore structure to clear the water of ice, thereby enabling conventional oil spill countermeasures to be used. Such a boom would be kept in place by two ice-going service vessels or by moored buoys. SINTEF NHL and NRC have performed a number of small-scale tests with a flexible boom in the NRC ice basin in Ottawa. The purpose of the tests was to measure the effectiveness of using a flexible boom for collecting ice, and to determine the loads associated with collecting the ice. In the tests, various boom configurations were towed against a broken ice field consisting of ice pieces typically 50–100 mm across and 30 mm thick. The ice concentration was usually 10/10, but it was reduced to 8/10 and 5/10 for two tests. The boom was towed at speeds of 20 and 50 mm-s−1. Both the width of the boom and the slackness of the boom were varied over reasonable ranges. Two six-component dynamometers were used to support the boom. Thus, the force components on each end of the boom were measured. Further, two video cameras were used to record the effectiveness of each boom configuration. In this paper, the full results of this test program are presented and the application of the test results to the full-scale situation are discussed. The tests show that, under certain conditions, the use of boom is feasible for ice management in oil-contaminated water.
Flow Past Oscillating Cylinders
Authors: Yeung R. W. , Vaidhyanathan M.
Published: June 2008

The phenomenon of vortex shedding by oscillating cylinders is a complex one. Its understanding is, however, of utmost importance in marine-related engineering, particularly in connection with motions of deep submersibles and marine risers. In this paper, computational results are presented so that the behavior of the shedding as a function of certain parameter space can be elucidated. A methodology based on the random vortex method and a complex-variable boundary-integral formulation is used to study both forced and vortex-induced oscillations of a circular cylinder. Preliminary evaluation of this method indicates that it has been successful in predicting a number of experimentally observed behavior, among which the phenomena of “lock-in” associated with oscillations of the cylinder are well captured.
Prestressing Buried Pipelines by Heating With Air
Authors: King G.
Published: June 2008

Buried pipelines operating at elevated temperatures experience high longitudinal compressive stresses because the surrounding soil prevents thermal expansion. At high operating temperatures, buried pipelines can push through the soil at bends and buckle catastrophically. In soft soils they can lose lateral stability, and they can develop plastic failures. Thermally induced problems can be prevented with varying degrees of success by using thicker wall pipe, higher strength steel, longer radius bends, deeper burial, better backfill compaction, and/or prestressing during construction. Prestressing is most appropriate for pipelines operating at temperatures more than 80°C above ambient. One technique for prestressing a buried pipeline, that has been found to be both easy and economical for a liquid sulphur pipeline in Alberta, is to heat it with hot air and bury it while it is still hot. Pipe diameter and prestressing temperature both have a significant impact on the kind of heating equipment that is required.
A Hydraulic Absorber for Wideband Vibration Reduction in Ship Hulls
Authors: Hsueh W. J. , Lee Y. J.
Published: June 2008

A vibration reduction of ship hulls by an active absorber system is proposed. In the scheme, a tuned mass is moved according to the hull vibration as measured by a multi-mode sensing system in order to generate a suitable active force for vibration reduction of hull girder. In order to supply the large amount of required power, a hydraulic servo system is implemented. Then the dynamic characteristic of the hydraulic system is considered for system design. Based on stochastic theory and optimal theory, the control law of the system is derived in order to approach the optimal level of vibration reduction. A 10-t absorber is applied to a 87,000-t oil tanker to demonstrate the feasibility of this scheme. The results show that the multi-peak values of resonance are suppressed in frequency response. Moreover, the vibration excited by propeller and engine is reduced to an extremely efficient level by this scheme.