bluuebunny/crossref_metadata_2025 huggingface dataset:
A Frequent Partial AZFc Deletion does not Render an Increased Risk of Spermatogenic Impairment in East Asians
Authors: Zhang F. , Li Z. , Wen B. , Jiang J. , Shao M. , Zhao Y. , He Y. , Song X. , Qian J. , Lu D. , Jin L.
Published: October 2005

The gene families in the AZFc region of the Y chromosome have been shown to be functionally important in human spermatogenesis. The gr/gr deletion, a partial AZFc deletion that reduces the copy numbers of all the AZFc gene families, was identified as a significant risk factor for spermatogenic impairment in Dutch, Spanish and Italians. However, the presence of this deletion in healthy French and Germans questioned its importance in male infertility. In this study, we have shown that the gr/gr deletion does not render an increased risk in Han Chinese. In fact, the gr/gr deletion is frequent (about 8%) in our survey of 886 East Asians from 8 ethnic groups. Furthermore, the DAZ1/DAZ2 deletion has been detected as the primary subtype of the gr/gr deletion in East Asians, though this doublet has been considered as crucial for normal spermatogenesis in Europeans. The different spermatogenic effects of various types of the partial AZFc deletion suggest that the functional difference between AZFc gene copies is a likely cause of inconsistent associations of the gr/gr deletion with spermatogenic impairment across populations.
Metabolic control analysis reveals an important role for diacylglycerol acyltransferase in olive but not in oil palm lipid accumulation
Authors: Ramli Umi S. , Salas Joaquin J. , Quant Patti A. , Harwood John L.
Published: October 2005

We applied metabolic control analysis to the Kennedy pathway for triacylglycerol formation in tissue cultures from the important oil crops, olive (Olea europaea L.) and oil palm (Elaeis guineensis Jacq.). When microsomal fractions were incubated at 30 °C rather than 20 °C, there was an increase in triacylglycerol labelling. This increase was accompanied by a build up of diacylglycerol (DAG) radioactivity in olive but not in oil palm, suggesting that the activity of DAG acyltransferase (DAGAT) was becoming limiting in olive. We used 2‐bromooctanoate as a specific inhibitor of DAGAT and showed that the enzyme had a flux control coefficient under the experimental conditions of 0.74 in olive but only 0.12 in oil palm. These data revealed important differences in the regulation of lipid biosynthesis in cultures from different plants and suggest that changes in the endogenous activity of DAGAT is unlikely to affect oil accumulation in oil palm crops.
Oxidized elafin and trappin poorly inhibit the elastolytic activity of neutrophil elastase and proteinase 3
Authors: Nobar Shila M. , Zani Marie‐Louise , Boudier Christian , Moreau Thierry , Bieth Joseph G.
Published: October 2005

Neutrophil proteinase‐mediated lung tissue destruction is prevented by inhibitors, including elafin and its precursor, trappin. We wanted to establish whether neutrophil‐derived oxidants might impair the inhibitory function of these molecules. Myeloperoxidase/H2O2 and N‐chlorosuccinimide oxidation of the inhibitors was checked by mass spectrometry and enzymatic methods. Oxidation significantly lowers the affinities of the two inhibitors for neutrophil elastase (NE) and proteinase 3 (Pr3). This decrease in affinity is essentially caused by an increase in the rate of inhibitory complex dissociation. Oxidized elafin and trappin have, however, reasonable affinities for NE (Ki = 4.0–9.2 × 10−9 m) and for Pr3 (Ki = 2.5–5.0 × 10−8 m). These affinities are theoretically sufficient to allow the oxidized inhibitors to form tight binding complexes with NE and Pr3 in lung secretions where their physiological concentrations are in the micromolar range. Yet, they are unable to efficiently inhibit the elastolytic activity of the two enzymes. At their physiological concentration, fully oxidized elafin and trappin do not inhibit more than 30% of an equimolar concentration of NE or Pr3. We conclude that in vivo oxidation of elafin and trappin strongly impairs their activity. Inhibitor‐based therapy of inflammatory lung diseases must be carried out using oxidation‐resistant variants of these molecules.
Axillopectoral muscle: An important anomaly in axillary surgery
Authors: Smart Philip James , Shayan Ramin , Mann G. Bruce
Published: October 2005

The axillopectoral muscle (Langer's axillary arch) is a common, though rarely noted, anatomical anomaly causing a range of rare clinical syndromes. Knowledge of the anomaly is increasingly important in the era of minimal access surgery and sentinel lymph node biopsy (SLNB) where it might produce false negative biopsies. We describe a case and review the current literature regarding its morphology. The axillopectoral muscle is found in 6% of human subjects, typically as a musculotendinous band 7–15 cm in length running between latissimus dorsi and pectoralis major with considerable morphological variation. It has been attributed to 2/15 false negative SLNB in one series. The axillopectoral muscle is common, variable and increasingly important in the era of SLNB.
Five‐year experience of outpatient laparoscopic cholecystectomy in Hong Kong
Authors: Chok Kenneth Siu‐Ho , Yuen Wai‐Key , Lau Hung , Chan‐Wing Lee Francis , Fan Sheung‐Tat
Published: October 2005

Laparoscopic cholecystectomy (LC) is the standard procedure for the management of symptomatic gallstone disease. There are many studies that have evaluated LC in an outpatient setting and the results are promising. The aim of the present study was to evaluate our experience in outpatient laparoscopic cholecystectomy during a five‐year period. We recruited 135 consecutive patients with symptomatic gall bladder disease to undergo outpatient LC from February 2000 to May 2004. The overall successful outpatient rate was 93% and it gradually increased from 72.7% to 100% during the five‐year period. The overnight admission and conversion rate decreased in concordance with the increase in the outpatient LC rate. No major complications were encountered and the pain control was good. Opiate‐free anaesthetic protocol, involvement of an experienced anaesthesiologist and surgeon, good preoperative counselling and a well‐equipped day surgery centre are the prerequisites for the success of this new procedure. Nevertheless, one should be well prepared before the commencement of the program and potential disastrous complications cannot be overlooked.
Duck (Anas platyrhynchos), Japanese quail (Coturnix coturnix japonica) and other avian interleukin‐2 reveals significant conservation of gene organization, promoter elements and functional residues
Authors: Sreekumar E. , Premraj A. , Rasool T. J.
Published: October 2005

We compared the gene, promoter and cDNA sequences, and the predicted protein structure of duck and quail interleukin‐2 (IL‐2), a major immunomodulatory cytokine, with the known sequences of other avian and human IL‐2. Analysis of the gene organization showed significant similarity with the overall organization of mammalian IL‐2 genes, with four exons and three introns and a very short 5′ untranslated regions. The second intron was the biggest in all the IL‐2 sequences. The third intron was of similar size in chicken and quail, whereas in duck it was found to be slightly longer. Promoter sequence analysis of the IL‐2 gene revealed remarkable conservation of the functionally important residues. The transcription factor binding sites such as those for AP‐1, NF‐AT, CD 28 RE and OCT, the TATA box and the predicted transcription start site with respect to chicken IL‐2 sequence showed total conservation in duck, quail and turkey IL‐2 promoters. Comparative analysis of the avian IL‐2 cDNAs such as those of chicken, turkey, duck, quail, goose and Muscovy duck, revealed significant conservation of the nucleotide and predicted amino acid sequences. They showed nucleotide identity levels varying from 75% to 85%, amino acid level identity from 58% to 72% and amino acid similarity from 71% to 80% with each other. In the predicted protein secondary structure, the four essential α‐helices and the hydrophobic amino acids in the heptad repeats forming the core structure of IL‐2 molecules were conserved in all the avian and the human IL‐2. The present study reveals high‐level conservation of the gene; cDNA structure and regulatory elements of avian IL‐2. This indicates highly conserved functions and probable functional cross‐reactivity of this major immunomodulatory cytokine among birds.
Novel polymorphism in the promoter region of the human nerve growth‐factor gene
Authors: Alam M. , Pravica V. , Fryer A. A. , Hawkins C. P. , Hutchinson I. V.
Published: October 2005

We describe a novel T to C transition at position −198 from the transcription start of the human nerve growth‐factor (NGF) gene. In British Caucasoid healthy control group that we have genotyped, T and C allele frequencies are 0.633 and 0.367, respectively. This polymorphism affects vitamin D receptor (VDR) binding to its motif in the NGF promoter.
Molecular physiology of SLC4 anion exchangers
Authors: Alper Seth L.
Published: October 2005

Plasmalemmal Cl−–HCO3− exchangers regulate intracellular pH and [Cl−] and cell volume. In polarized epithelial cells, they contribute also to transepithelial secretion and reabsorption of acid–base equivalents and of Cl−. Members of both the SLC4 and SLC26 mammalian gene families encode Na+‐independent Cl−–HCO3− exchangers. Human SLC4A1/AE1 mutations cause either the erythroid disorders spherocytic haemolytic anaemia or ovalocytosis, or distal renal tubular acidosis. SLC4A2/AE2 knockout mice die at weaning. Human SLC4A3/AE3 polymorphisms have been associated with seizure disorder. Although mammalian SLC4/AE polypeptides mediate only electroneutral Cl−–anion exchange, trout erythroid AE1 also promotes osmolyte transport and increased anion conductance. Mouse AE1 is required for DIDS‐sensitive erythroid Cl− conductance, but definitive evidence for mediation of Cl− conductance is lacking. However, a single missense mutation allows AE1 to mediate both electrogenic SO42−–Cl− exchange or electroneutral, H+‐independent SO42−–SO42− exchange. In the Xenopus oocyte, the AE1 C‐terminal cytoplasmic tail residues reported to bind carbonic anhydrase II are dispensable for Cl−–Cl− exchange, but required for Cl−–HCO3− exchange. AE2 is acutely and independently inhibited by intracellular and extracellular H+, and this regulation requires integrity of the most highly conserved sequence of the AE2 N‐terminal cytoplasmic domain. Individual missense mutations within this and adjacent regions identify additional residues which acid‐shift pHo sensitivity. These regions together are modelled to form contiguous surface patches on the AE2 cytoplasmic domain. In contrast, the N‐terminal variant AE2c polypeptide exhibits an alkaline‐shifted pHo sensitivity, as do certain transmembrane domain His mutants. AE2‐mediated anion exchange is also stimulated by ammonium and by hypertonicity by a mechanism sensitive to inhibition by chelation of intracellular Ca2+ and by calmidazolium. This growing body of structure–function data, together with increased structural information, will advance mechanistic understanding of SLC4 anion exchangers.
O2 sensing at the mammalian carotid body: why multiple O2 sensors and multiple transmitters?
Authors: Prabhakar Nanduri R.
Published: October 2005

Carotid bodies are the sensory organs for detecting systemic hypoxia and the ensuing reflexes prevent the development of tissue/cellular hypoxia. Although every mammalian cell responds to hypoxia, O2 sensing by the carotid body is unique in that it responds instantaneously (within seconds) to even a modest drop in arterial PO2. Sensing hypoxia in the carotid body requires an initial transduction step involving O2 sensor(s) and transmitter(s) for subsequent activation of the afferent nerve ending. This brief review focuses on: (a) whether the transduction involves ‘single’ or ‘multiple’ O2 sensors; (b) the identity of the excitatory transmitter(s) responsible for afferent nerve activation by hypoxia; and (c) whether inhibitory transmitters have any functional role. The currently proposed O2 sensors include various haem‐containing proteins, and a variety of O2‐sensitive K+ channels. It is proposed that the transduction involves an ensemble of, and interactions between, haem‐containing proteins and O2‐sensitive K+‐channel proteins functioning as a ‘chemosome’; the former for conferring sensitivity to wide range of PO2 values and the latter for the rapidity of the response. Hypoxia releases both excitatory and inhibitory transmitters from the carotid body. ATP is emerging as an important excitatory transmitter for afferent nerve activation by hypoxia. Whereas the inhibitory messengers act in concert with excitatory transmitters like a ‘push–pull’ mechanism to prevent over excitation, conferring the ‘slowly adapting’ nature of the afferent nerve activation during prolonged hypoxia. Further studies are needed to test the interactions between putative O2 sensors and excitatory and inhibitory transmitters in the carotid body.
Vasoconstriction and blood flow responses in visceral arteries to mental task in humans
Authors: Hayashi Naoyuki , Someya Nami , Endo Masako Yamaoka , Miura Akira , Fukuba Yoshiyuki
Published: October 2005

The vascular responses to mental task in visceral arteries in humans have not been elucidated. We observed the responses in the renal (RA) and superior mesenteric (SMA) arteries to mental stress, using simultaneous pulsed and echo Doppler ultrasound flowmetry. Nine healthy females performed a computerized colour word conflict test (CWT) for 3 min. The mean blood velocity (MBV) in the right RA and SMA, heart rate (HR) and blood pressure were measured. The mean arterial pressure (MAP) was divided by the flow velocity to assess the vascular resistance (VR). The CWT significantly increased the MAP, HR and VR in both arteries from the first minute. During the CWT, flow in the RA decreased significantly at the third minute relative to baseline, while flow in the SMA showed no significant change from the first to the third minute. The degree of vasoconstriction in the RA bed was greater than that in the SMA bed. These results suggest that the mental task causes vasoconstriction in visceral arteries, and imply that it induces differential blood flow and vascular responses in visceral arteries.
Stress‐dependent and ‐independent expression of the myogenic regulatory factors and the MARP genes after eccentric contractions in rats
Authors: Hentzen Eric R. , Lahey Michele , Peters David , Mathew Liby , Barash Ilona A. , Fridén Jan , Lieber Richard L.
Published: October 2005

The relationship between muscle mechanical conditions and gene expression was investigated by varying both stress and contraction mode imposed upon rat dorsiflexors (n= 25), activating them at high or low frequencies (150 Hz or 40 Hz) either eccentrically or isometrically. Muscle physiological, immunohistochemical and gene expression changes were then measured 24 h after the exercise bout. Peak stress was the best predictor of muscle injury, independent of contraction mode (i.e. eccentric or isometric). When peak stresses were matched, no physiological or immunohistochemical differences were detected between isometric and eccentric contractions. The expression of certain myogenic regulatory and muscle ankyrin repeat protein (MARP) genes (myoD, myogenin, MLP and CARP) depended both on peak muscle stress achieved during contraction and contraction mode. In contrast, Arpp/Ankrd2 was dramatically upregulated only by eccentric contractions, but not by isometric contractions, even though the stress level of the eccentric contractions varied over a three‐fold range and overlapped with that of the isometric group. The role that Arpp/Ankrd2 upregulation plays in the biological response to eccentric contraction remains to be determined, as does the control mechanism whereby the expression of certain genes (such as myoD, myogenin, MLP and CARP) is sensitive to muscle stress while another (Arpp/Ankrd2) is sensitive only to contraction mode.
Effects of focal injection of kainic acid into the mouse hippocampus in vitro and ex vivo
Authors: Le Duigou Caroline , Wittner Lucia , Danglot Lydia , Miles Richard
Published: October 2005

Intra‐hippocampal kainate injection induces an epileptiform activity termed status epilepticus. We examined the emergence of this activity with extracellular and intracellular records of responses (1) to focal kainate (KA) application in slices of mouse hippocampus and (2) of slices from mice injected with KA. The effects varied with distance from the injection site of KA. At distances less than ∼800 μm, KA injection induced a strong increase in extracellular firing which ceased after 2–4 min. Pyramidal cells in this zone fired and depolarized to a potential at which action potentials were no longer evoked. No further activity was detected near the injection site for 3–5 h. In longitudinal slices of the CA3 region, firing induced by KA injection spread at a velocity close to 1 × 10−4 mm ms−1. The velocity increased to ∼1 × 10−1 mm ms−1 when synaptic inhibition was blocked, suggesting that inhibitory processes normally restrict the spread of firing. At distances of 1.5–2.5 mm, KA injection induced a short‐term increase in firing which was maintained, and often increased and rhythmic at gamma frequencies at 2–5 h after injection. We also examined slices prepared from animals injected with KA, at a delay of 2–5 h corresponding to the expression of status epilepticus. Near the injection site, Gallyas silver staining revealed cellular degeneration, and no activity was recorded. Interictal‐like activity was generated by ipsilateral slices distant from KA injection. Contralateral slices also generated an interictal‐like activity, but no cell death was detected. Hippocampal oscillations generated at distant sites may be associated with status epilepticus.
Alkalosis increases muscle K+ release, but lowers plasma [K+] and delays fatigue during dynamic forearm exercise
Authors: Sostaric Simon M. , Skinner Sandford L. , Brown Malcolm J. , Sangkabutra Termboon , Medved Ivan , Medley Tanya , Selig Steve E. , Fairweather Ian , Rutar Danny , McKenna Michael J.
Published: October 2005

Alkalosis enhances human exercise performance, and reduces K+ loss in contracting rat muscle. We investigated alkalosis effects on K+ regulation, ionic regulation and fatigue during intense exercise in nine untrained volunteers. Concentric finger flexions were conducted at 75% peak work rate (∼3 W) until fatigue, under alkalosis (Alk, NaHCO3, 0.3 g kg−1) and control (Con, CaCO3) conditions, 1 month apart in a randomised, double‐blind, crossover design. Deep antecubital venous (v) and radial arterial (a) blood was drawn at rest, during exercise and recovery, to determine arterio‐venous differences for electrolytes, fluid shifts, acid–base and gas exchange. Finger flexion exercise barely perturbed arterial plasma ions and acid–base status, but induced marked arterio‐venous changes. Alk elevated [HCO3−] and P, and lowered [H+] (P < 0.05). Time to fatigue increased substantially during Alk (25 ± 8%, P < 0.05), whilst both [K+]a and [K+]v were reduced (P < 0.01) and [K+]a‐v during exercise tended to be greater (P= 0.056, n= 8). Muscle K+ efflux at fatigue was greater in Alk (21.2 ± 7.6 µmol min−1, 32 ± 7%, P < 0.05, n= 6), but peak K+ uptake rate was elevated during recovery (15 ± 7%, P < 0.05) suggesting increased muscle Na+,K+‐ATPase activity. Alk induced greater [Na+]a, [Cl−]v, muscle Cl− influx and muscle lactate concentration ([Lac−]) efflux during exercise and recovery (P < 0.05). The lower circulating [K+] and greater muscle K+ uptake, Na+ delivery and Cl− uptake with Alk, are all consistent with preservation of membrane excitability during exercise. This suggests that lesser exercise‐induced membrane depolarization may be an important mechanism underlying enhanced exercise performance with Alk. Thus Alk was associated with improved regulation of K+, Na+, Cl− and Lac−.
Nitric oxide inhibition and the impact on renal nerve‐mediated antinatriuresis and antidiuresis in the anaesthetized rat
Authors: Bagnall N. M. , Dent P. C. , Walkowska A. , Sadowski J. , Johns E. J.
Published: October 2005

The contribution of nitric oxide (NO) to the antinatriuresis and antidiuresis caused by low‐level electrical stimulation of the renal sympathetic nerves (RNS) was investigated in rats anaesthetized with chloralose–urethane. Groups of rats, n= 6, were given i.v. infusions of vehicle, l‐NAME (10 μg kg−1 min−1), 1400W (20 μg kg−1 min−1), or S‐methyl‐thiocitrulline (SMTC) (20 μg kg−1 min−1) to inhibit NO synthesis non‐selectively or selectively to block the inducible or neuronal NOS isoforms (iNOS and nNOS, respectively). Following baseline measurements of blood pressure (BP), renal blood flow (RBF), glomerular filtration rate (GFR), urine flow (UV) and sodium excretion (UNaV), RNS was performed at 15 V, 2 ms duration with a frequency between 0.5 and 1.0 Hz. RNS did not cause measurable changes in BP, RBF or GFR in any of the groups. In untreated rats, RNS decreased UV and UNaV by 40–50% (both P < 0.01), but these excretory responses were prevented in l‐NAME‐treated rats. In the presence of 1400W i.v., RNS caused reversible reductions in both UV and UNaV of 40–50% (both P < 0.01), while in SMTC‐treated rats, RNS caused an inconsistent fall in UV, but a significant reduction (P < 0.05) in UNaV of 21%. These data demonstrated that the renal nerve‐mediated antinatriuresis and antidiuresis was dependent on the presence of NO, generated in part by nNOS. The findings suggest that NO importantly modulates the neural control of fluid reabsorption; the control may be facilitatory at a presynaptic level but inhibitory on tubular reabsorptive processes.
Interaction between spontaneous and neurally mediated regulation of smooth muscle tone in the rabbit corpus cavernosum
Authors: Hashitani Hikaru , Yanai Yoshimasa , Shirasawa Nobuyuki , Soji Tsuyoshi , Tomita Akihiro , Kohri Kenjiro , Suzuki Hikaru
Published: October 2005

Interaction between spontaneous and neurally mediated regulation of tone in the corpus cavernosum smooth muscle (CCSM) of the rabbit was investigated. Changes in isometric muscle tension, intracellular Ca2+concentration ([Ca2+]i) and membrane potential were recorded. CCSM developed spontaneous contractions, transient increases in [Ca2+]i(Ca2+transients) and depolarizations. This spontaneous activity was abolished by blocking L‐type Ca2+channels (nicardipine, 1 μm), sarcoplasmic reticulum Ca2+pump activity (cyclopiazonic acid, 10 μm), Ca2+‐activated Cl−channels (niflumic acid, 10 μm) or cyclooxygenase‐2 (COX‐2; NS‐398, 1 μm). Transmural nerve stimulation initiated either α‐adrenergic contractions or nitrergic relaxations of CCSM depending on the level of muscle tone. NS‐398 suppressed nerve‐evoked contractions by about 70% but caused only a 40% reduction in the corresponding Ca2+transient. Blocking nitric oxide synthase withNω‐nitro‐l‐arginine (LNA, 100 μm) reinforced nerve‐evoked Ca2+transients by about 150%, whilst increasing the corresponding Ca2+transients by only 20%. In CCSM preparations that had been pre‐contracted with either noradrenaline (0.3 μm) or prostaglandinF2α(0.1 μm), nerve stimulation inhibited about 70% of the contraction and caused only a 20% decrease in [Ca2+]i. Fluorescent immunohistochemistry with COX‐2 antibodies and the reverse transcriptase‐polymerase chain reaction (RT‐PCR) method showed that the enzyme and its mRNA were highly expressed in the CCSM. These results suggest that spontaneously produced prostaglandins (PGs) not only contribute to the generation of spontaneous contractions but also facilitate nerve‐evoked contractions. Conversely, spontaneously released nitric oxide (NO) suppresses excitation. Thus, interaction between spontaneous and neurally mediated regulation of CCSM tone may be fundamental to maintaining the muscle contractility. In addition, both PGs and NO appear to alter CCSM tone with only small changes in [Ca2+]i.
A Parametric Finite Element Geometric Analysis of a Pressurized Sphere with Cylindrical Flush Nozzle Outlet
Authors: Makaraci Murat
Published: October 2005

A spherical, internally pressurized vessel with cylindrical flush nozzle outlet is analyzed in a parametric, linear displacement based finite element scheme. Geometric effects of outer convex radius design on the whole vessel body are investigated. An inside sharp corner where spherical section is joined with the flush nozzle outlet contributes to stress as well as degree of curvature in the outer convex radius. Stress and deformation states exhibit material, geometry, and internal pressure level dependencies. An important feature of the method, mesh convergence, is also validated for reliability of the results. Severe stress distributions and strain accumulations can be reduced through controlling outer geometric parameters. Materials having diverse mechanical properties such as carbon steel, Ti-Al-V alloy, near-eutectic Sn63-Pb37 solder alloy, and Nylon 66 are used for the vessel structure to reveal material dependence. Lower order elements are recommended for computational analysis.
Thread Friction Torque in Bolted Joints
Authors: Nassar Sayed A. , Matin Payam H. , Barber Gary C.
Published: October 2005

In this paper, formulas are developed for the calculation of the effective thread friction radius in fasteners, in order to determine the thread friction torque component. Due to the lack of exact formulas in the literature, current practice uses the average value of the minor and major thread radii, as an approximation, for determining the thread friction torque component. Results provided by these formulas are compared with those given by the current practice that uses the average value of the minor and major thread radii, instead of the exact value. It is well known that the torque-tension relationship in threaded fastener applications is highly sensitive to the friction torque components: between threads, and under the turning fastener head or nut. Even moderate variations or inaccuracies in determining the friction torque components would significantly impact the fastener tension and the joint clamp load. High accuracy in the estimation of the friction torque components is critical, as it directly affects the reliability, safety, and the quality of bolted assemblies. This analysis focuses on the thread friction torque component. The new formulas for the thread friction radius are developed for a mathematical model of a bolted joint using five assumed scenarios of the contact pressure between male and female threads. Because of the fact that the variation in the sliding speed of various points on a thread surface is insignificant, a uniform thread friction coefficient is used in the analysis. However, a contact area weighted average value is used for the thread friction coefficient. Numerical results and error analysis are presented in terms of a single nondimensional variable, namely, the ratio between the major and minor thread radii.
Robust Reliability Design of Banjo Flange With Arbitrary Distribution Parameters
Authors: Zhang Yimin , He Xiangdong , Liu Qiaoling , Wen Bangchun
Published: October 2005

The perturbation method, the Edgeworth series, the reliability-based optimization, the reliability sensitivity technique, and the robust design are employed to present a practical and effective approach for the robust reliability design of the Banjo flange with arbitrary distribution parameters on the condition of known first four moments of original random variables. The theoretical formulas of robust reliability design for the Banjo flange with arbitrary distribution parameters are obtained. The respective program can be used to obtain the robust reliability design parameters of the Banjo flange with arbitrary distribution parameters accurately and quickly.
An Analytical Solution for Evaluating Gasket Stress Change in Bolted Flange Connections Subjected to High Temperature Loading
Authors: Bouzid Abdel-Hakim , Nechache Akli
Published: October 2005

The tightness of bolted flanged joints subjected to elevated temperature is not properly addressed by flange design codes. The development of an analytical method based on the flexibility of the different joint components and their elastic interaction could serve as a powerful tool for elevated temperature flange designs. This paper addresses the effect of the internal fluid operating temperature on the variation of the bolt load and consequently on the gasket stress in bolted joints. The theoretical analysis used to predict the gasket load variation as a result of unequal radial and axial thermal expansion of the joint elements is outlined. It details the analytical basis of the elastic interaction model and the thermally induced deflections that are used to evaluate the load changes. Two flange joint type configurations are treated: a joint with identical pair of flanges and a joint with a cover plate. The analytical models are validated and verified by comparison to finite element results.
Use of a Bubble Tracking Method for Prediction of Downhole Natural Separation Efficiency
Authors: Liu Bin , Prado Mauricio
Published: October 2005

For any pumping artificial lift system in the petroleum industry, the free gas significantly affects the performance of the pump and the system above the pump. A model, though not a complete two-phase flow model, has been developed for the effective prediction of separation efficiency across a wide range of production conditions. The model presented is divided into two main parts, the single-phase flow-field solution and the bubble-tracking method. The first part of the model solves the single-phase liquid flow field using the computational fluid dynamics approach. Then, a simple bubble-tracking method was applied to estimate the down-hole natural separation efficiency for two-phase flow. A comparison between the results of the model and the experimental data was conducted. It shows a very good agreement with the experimental data for lower gas void fractions (bubble flow regime).
Seismic Fragility Analysis of a Water Storage Structure
Authors: Bhargava Kapilesh , Ghosh A. K. , Ramanujam S.
Published: October 2005

Probabilistic seismic risk assessment (PSRA) of a structure is essential to identify the seismic vulnerability of structural members associated with the different stages of damage. Seismic fragility evaluation is a widely accepted approach to develop seismic vulnerability information for the structures. The present paper is concerned with the seismic response and fragility evaluation of a water storage structure. Seismic analysis has been carried out considering the hydrodynamic effects of the contained water. For seismic fragility evaluation, the various parameters that could affect the seismic structural response have been identified as material strength of concrete, structural damping available within the structure, and the normalized ground motion response spectral shape. Based on this limited case study, the seismic fragility of the structure is developed as families of conditional probability curves plotted as a function of peak ground acceleration at the location of interest. The paper presents the method adopted for the seismic fragility evaluation that incorporates the various randomness and uncertainty associated with the parameters under consideration. Typical results of fragility have been presented for different stresses, i.e., corresponding to the different modes of failure. The results of the fragility study show that the seismic structural response at the location of interest is quite sensitive to the randomness and uncertainty associated with the variable parameters considered in the present study. These results will be useful for PSRA studies.
On Circumferential Disposition of Pipe Defects by Long-Range Ultrasonic Guided Waves
Authors: Li Jian
Published: October 2005

Ultrasonic guided waves have been used extensively for long-range pipe inspections. The technique is based on detecting the guided wave echoes reflected from pipe defects located at a remote distance. The axial location of the defect from the transducer can be determined by the arrival time of the echo. However, further information about the defect, such as the circumferential size or distribution of the defect, is hard to obtain with conventional guided waves. This problem will be a critical issue for applications, such as discriminating the pipe corrosion defects from pipe welds. In this paper, a circumferential guided wave array is built for sending and receiving guided waves along the pipe. All of the elements are connected to a single channel pulser/receiver through multiplexers. An algorithm based on two-dimensional (2D) blind deconvolution is developed to process the guided wave echoes acquired by the multiplexed circumferential transducer array. The output of the algorithm can be utilized for evaluating the circumferential distributions and geometry of the defects. The processing algorithm is verified via both numerical simulations and experiments in the paper. This circumferential sizing algorithm can serve as an effective postanalysis tool for most available guided wave pipe inspection systems.
Dispersion anomalies of shear horizontal guided waves in two- and three-layered plates
Authors: Alshits V. I. , Deschamps M. , Lyubimov V. N.
Published: October 2005

The dispersion spectra of SH guided waves are studied both analytically and numerically for two-layered plates with a plane of propagation being the plane of transverse isotropy. The boundary-value problems are considered for a plate with free, clamped, or clamped/free surfaces. It is noticed that formally the problem is very similar to that for symmetric and antisymmetric Lamb waves in a homogeneous plate. On this basis the Mindlin’s approach of a bound grid is applied for an analysis. It is found that the studied spectra are characterized by the following specific features. They have two asymptotic levels ct1 and ct2 corresponding to the speeds of SH bulk waves in both layers. In the vicinity of the upper level (ct2) dispersion curves form a step-like pattern tending to ct2 in succession one by one with further going down to the lower asymptote ct1. Over the level ct2 there is a zone, where dispersion curves have a wavy form similar to that in spectra of Lamb waves in homogeneous plates. It is shown that the families of dispersion branches related to the boundary conditions of free and clamped surfaces cross each other at the same types of nodes of Mindlin’s grid as those for symmetric and antisymmetric Lamb waves in a free homogeneous plate. The tracing speed level v=v0 is found where the appropriate families of dispersion curves cross each other beyond the nodes of Mindlin’s grid. It is proved that the spectra of symmetric and antisymmetric SH guided waves in symmetric three-layered plates with free or clamped faces are described by the same four equations as for the studied two-layered plates with free, clamped, free/clamped or clamped/free surfaces.
Retrieving the Green’s function in an open system by cross correlation: A comparison of approaches (L)
Authors: Wapenaar Kees , Fokkema Jacob , Snieder Roel
Published: October 2005

We compare two approaches for deriving the fact that the Green’s function in an arbitrary inhomogeneous open system can be obtained by cross correlating recordings of the wave field at two positions. One approach is based on physical arguments, exploiting the principle of time-reversal invariance of the acoustic wave equation. The other approach is based on Rayleigh’s reciprocity theorem. Using a unified notation, we show that the result of the time-reversal approach can be obtained as an approximation of the result of the reciprocity approach.
Reverberation effects in acoustical resonators used for bubble measurements
Authors: Farmer David M. , Vagle Svein , Booth Donald
Published: October 2005

Attention has recently been drawn to the potential for errors to arise in the classical interpretation of bubble behavior in a reverberant cavity. The bubbles contribute to the reverberant field and, in a reciprocal effect, their response is modified by it. These reverberant loading effects have been shown to be important in the case of a bubble placed in a reverberant cavity. Here, the related topic of reverberant loading in a parallel plate acoustical resonator within which the bubbles are randomly distributed is addressed. Calculations are carried out for random bubble distributions consistent with measured populations. It is shown that, although large reverberation effects do occur, these are confined to relatively narrow bandwidths. Only when these narrow bands coincide with the resonator harmonics are resonator measurements significantly affected. For the specific geometry used to measure ocean bubble populations, reverberation effects turn out to be small. Other resonator dimensions or designs, however, could lead to greater effects, and the calculations presented here emphasize the importance of properly evaluating the reverberation influence for any specific application. Procedures for implementing corrections are identified.
A new method for estimating shear-wave velocity in marine sediments from radiation impedance measurements
Authors: Kimura Masao
Published: October 2005

Shear-wave velocity is one of the important parameters that characterize the physical properties of marine sediments. In this study, a new method is proposed for measuring shear-wave velocity in marine sediments by using radiation impedance. Shear-wave velocities for three kinds of urethane rubber with different Japanese Industrial Standards hardness values were obtained by radiation impedance and time-of-flight measurement techniques. It was shown that the values of the shear-wave velocity measured by the radiation impedance method were consistent with those of time-of-flight measurements. It was then shown that the shear-wave velocities for air- and water-saturated beach sands are different. It was also found that the indicated shear-wave velocity is dependent on the vibrating plate radius because the instrument measures an average shear-wave velocity within a depth window beneath the plate; the larger the plate radius, the deeper the averaging window. Finally, measurements were made on two-layered media in which air-saturated beach sand or urethane rubber was covered with air-saturated clay, and the relationship between the thickness of the clay layer and the indicated shear-wave velocity was investigated.
An experimental investigation of two active segmented partition arrays
Authors: Leishman Timothy W. , Tichy Jiri
Published: October 2005

This paper addresses the construction, measurement, and analysis of two active segmented partition arrays (ASP arrays) for use in active sound transmission control. The control objective for each array was to actively minimize principal transmitting surface vibrations to induce high transmission loss. The arrays incorporated four adjacent lightweight modules with composite single or double leaves and small loudspeakers as actuators. A normal-incidence transmission loss measurement system was developed to evaluate their performances under passive and active conditions. Measurement results were compared to results for passive benchmark partitions and theoretical predictions. Four decentralized single-error-input, single-output filtered-x controllers were used with the arrays. They were shown to perform at least as well as a centralized multiple-error-input, multiple-output controller, with good error signal reductions and stability. Scanning laser vibrometer measurements confirmed the ability of the double-composite-leaf ASP to efficiently and globally minimize its transmitting surface vibrations to produce high transmission loss. Its average transmission loss over the active measurement bandwidth (30–290Hz) was 56dB—a full 34dB greater than that of the single-composite-leaf ASP. The work confirms that a properly configured lightweight ASP can produce very high transmission loss through vibration control techniques.
Performance and limitations of spectral factorization for ambient noise sub-bottom profiling
Authors: Harrison Chris H.
Published: October 2005

Using a drifting vertical array as a means to measure noise directionality one can infer reflection coefficient vs angle and frequency. This can be converted to a time-varying impulse response, i.e., a sub-bottom profile, by using spectral factorization to recover the phase. Limitations of the technique are discussed with simulations and experiment. First, spectral factorization provides a minimum phase realization of the impulse response for the given spectrum, whereas the true reflection coefficient may not actually be minimum phase. Second, the beam width, determined by array length, slightly smudges the interference fringes that are characteristic of the reflection coefficient. This reduction in frequency resolution reduces the maximum depth to which layers can be detected. Consideration of the detailed mechanism leads to a way of improving frequency resolution and hence maximum depth. Spectral factorization tends to function well unless the impedance contrast between water and upper layers is very small. The depth limitations due to beam width will usually be more important than those of spectral factorization even with the proposed recovery of frequency resolution. At 4kHz design frequency the layer structure thus determined during a 6km drift compares well with a seismic boomer down to 15m.
Ocean sound channel ray path perturbations from internal-wave shear and strain
Authors: Duda Timothy F.
Published: October 2005

The relative importance of internal-wave strain and internal-wave shear on perturbation of acoustic ray trajectories in the ocean is analyzed. Previous estimates based on the Garrett-Munk internal-wave spectral model are updated using data from recent field studies of internal waves. Estimates of the ratio of the rms shear effect to the rms strain effect based on data from the upper kilometer of ocean are as high as 0.25–0.4, exceeding the estimates of 0.08–0.17 stemming from the model. Increased strength of three phenomena that have shear to strain ratios higher than the internal-wave average can cause this effect. These are near-inertial waves, internal tides, and vortical modes.
Symmetric mode resonance of bubbles attached to a rigid boundary
Authors: Payne Edward M. B. , Illesinghe Suhith J. , Ooi Andrew , Manasseh Richard
Published: October 2005

Experimental results are compared with a theoretical analysis concerning wall effects on the symmetric mode resonance frequency of millimeter-sized air bubbles in water. An analytical model based on a linear coupled-oscillator approximation is used to describe the oscillations of the bubbles, while the method of images is used to model the effect of the wall. Three situations are considered: a single bubble, a group of two bubbles, and a group of three bubbles. The results show that bubbles attached to a rigid boundary have lower resonance frequencies compared to when they are in an infinite uniform liquid domain (referred to as free space). Both the experimental data and theoretical analysis show that the symmetric mode resonance frequency decreases with the number of bubbles but increases as the bubbles are moved apart. Discrepancies between theory and experiment can be explained by the fact that distortion effects due to buoyancy forces and surface tension were ignored. The data presented here are intended to guide future investigations into the resonances of larger arrays of bubbles on rigid surfaces, which may assist in surface sonochemistry, sonic cleaning, and micro-mixing applications.
Time-resolved modal decomposition based on the Linear Prediction Method—Applied for crack detection
Authors: Veres István A. , Profunser Dieter M.
Published: October 2005

A nondestructive technique for testing and monitoring structures is presented, this uses guided waves to avoid a long scanning process. In contrast to other techniques that use guided waves this method can be applied to any structure made of a material that can be dispersive, strongly attenuating, and anisotropic, without the need of special adaptation. This is demonstrated on beams made of aluminum and wood. The propagating waves are reflected at any acoustic discontinuity, for example, by cracks and defects. In strongly attenuating materials such as wood, it is necessary to work with low frequencies, but due to the correspondingly long wavelength, the incident and reflected (from defects and boundaries) waves superimpose. The presented new signal processing technique allows the determination of the wave modes and their propagation direction very accurately in the time domain. Incident and reflected waves can easily be distinguished by the propagation direction. Since the wave mode is known from signal processing the right group velocity is applied for an accurate calculation of the defect location.
Off-axis effects on the multipulse structure of sperm whale usual clicks with implications for sound production
Authors: Zimmer Walter M. X. , Madsen Peter T. , Teloni Valeria , Johnson Mark P. , Tyack Peter L.
Published: October 2005

Sperm whales (Physeter macrocephalus) produce multipulsed clicks with their hypertrophied nasal complex. The currently accepted view of the sound generation process is based on the click structure measured directly in front of, or behind, the whale where regular interpulse intervals (IPIs) are found between successive pulses in the click. Most sperm whales, however, are recorded with the whale in an unknown orientation with respect to the hydrophone where the multipulse structure and the IPI do not conform to a regular pulse pattern. By combining far-field recordings of usual clicks with acoustic and orientation information measured by a tag on the clicking whale, we analyzed clicks from known aspects to the whale. We show that a geometric model based on the bent horn theory for sound production can explain the varying off-axis multipulse structure. Some of the sound energy that is reflected off the frontal sac radiates directly into the water creating an intermediate pulse p1/2 seen in off-axis recordings. The powerful p1 sonar pulse exits the front of the junk as predicted by the bent-horn model, showing that the junk of the sperm whale nasal complex is both anatomically and functionally homologous to the melon of smaller toothed whales.
Ice-Sheet and Sea-Level Changes
Authors: Alley Richard B. , Clark Peter U. , Huybrechts Philippe , Joughin Ian
Published: October 2005

Future sea-level rise is an important issue related to the continuing buildup of atmospheric greenhouse gas concentrations. The Greenland and Antarctic ice sheets, with the potential to raise sea level ∼70 meters if completely melted, dominate uncertainties in projected sea-level change. Freshwater fluxes from these ice sheets also may affect oceanic circulation, contributing to climate change. Observational and modeling advances have reduced many uncertainties related to ice-sheet behavior, but recently detected, rapid ice-marginal changes contributing to sea-level rise may indicate greater ice-sheet sensitivity to warming than previously considered.
Recent Ice-Sheet Growth in the Interior of Greenland
Authors: Johannessen Ola M. , Khvorostovsky Kirill , Miles Martin W. , Bobylev Leonid P.
Published: October 2005

A continuous data set of Greenland Ice Sheet altimeter height from European Remote Sensing satellites (ERS-1 and ERS-2), 1992 to 2003, has been analyzed. An increase of 6.4 ± 0.2 centimeters per year (cm/year) is found in the vast interior areas above 1500 meters, in contrast to previous reports of high-elevation balance. Below 1500 meters, the elevation-change rate is –2.0 ± 0.9 cm/year, in qualitative agreement with reported thinning in the ice-sheet margins. Averaged over the study area, the increase is 5.4 ± 0.2 cm/year, or ∼60 cm over 11 years, or ∼54 cm when corrected for isostatic uplift. Winter elevation changes are shown to be linked to the North Atlantic Oscillation.