bluuebunny/crossref_metadata_2025_split huggingface dataset:
Requirement of the fixed end for spontaneous beating in flagella
Authors: Fujimura Miki , Okuno Makoto 
Published: March 2006

SUMMARYIt is well known that any part of a flagellum has the ability to bend. However, it is not clearly understood how flagella generate successive bending waves spontaneously. Some micromanipulation experiments have suggested that the base of the flagellum is required. By contrast, spontaneous bending waves could be generated in computer simulation work if the microtubules were tied together at one end. We hypothesized that the basal structure of flagella can only act as a tied end when the outer doublet microtubules are tightly bound together so as not to slide. We developed a new technique for introducing local inhibition at any position on the demembranated and reactivated flagellum. The flagellum maintained spontaneous beating when the local inhibition was introduced at any position on it. In addition, spontaneous beating occurred without the basal body when an artificial fixed region was introduced to the flagellum. We conclude that the axoneme, a bundle of microtubules, requires the fixed end for spontaneous beating.
Functional consequences of activity-dependent synaptic enhancement at a crustacean neuromuscular junction
Authors: Stein Wolfgang , Smarandache Carmen R. , Nickmann Melanie , Hedrich Ulrike B. S. 
Published: March 2006

SUMMARY
This study provides evidence that activity-dependent synaptic enhancement at a neuromuscular junction modifies the characteristics of force production of the receiving muscle during rhythmic motor neuron discharge patterns. Long-lasting augmentation of the excitatory junction potentials (EJPs)quickens and strengthens the muscle response to a given motor pattern. We used the muscle gm6 of the crab Cancer pagurus to study the functional consequences and temporal dynamics of facilitation and augmentation. This stomach muscle is driven by the rhythmic activity of the gastric mill central pattern generator in the stomatogastric nervous system. We tested the response of this muscle to rhythmic motor drive using a variety of gastric mill-like stimulations.
EJPs recorded in muscle gm6 were initially small but are summated and facilitated strongly with continuous stimulation. Facilitation increased with shorter interspike intervals and possessed a time constant of decay &lt;1 s.
During gastric mill rhythms, motor neuron activity was by contrast represented by bursts of activity with intermittent pauses of several seconds. Recordings in intact animals and in the isolated nervous system showed a great variability in firing frequency and temporal distribution of motor neuron bursts. Train stimulations with various stimulus frequencies (5 Hz, 10 Hz, 20 Hz) and inter-train intervals (2 s, 4 s, 8 s, 16 s, 32 s) revealed that augmentation acted in addition to facilitation. Augmentation increased muscle EJPs during stimulations with inter-train intervals of 16 s or less. The effects of augmentation increased with shorter inter-train intervals, but were independent of stimulus frequency.
Augmentation also contributed to the electrical response of the muscle during gastric mill rhythms, which were obtained in vitro and in vivo, and was also reflected by an increase of muscle force and the slope of force development during repetitive train stimulation. We conclude that the augmentation of EJPs at the neuromuscular junction tunes the muscle response to support force production during rhythmic motor patterns.
Extracellular pH changes activate the p38-MAPK signalling pathway in the amphibian heart
Authors: Stathopoulou Konstantina , Gaitanaki Catherine , Beis Isidoros 
Published: March 2006

SUMMARYWe investigated the activation of the p38-MAPK signalling pathway during extracellular pH changes in the isolated perfused amphibian heart. Extracellular alkalosis (pH 8.5 or 9.5) maximally activated p38-MAPK within 2 min (4.17- and 3.20-fold, respectively) and this effect was reversible since the kinase phosphorylation levels decreased upon reperfusing the heart with normal Tris–Tyrode's buffer. Extracellular acidosis also activated p38-MAPK moderately, but persistently (1.65-fold, at 1 min and 1.91-fold, at 60 min). The alkalosis-induced p38-MAPK activation depended upon the Na+/H+ exchanger (NHE) and Na+/K+-ATPase, because it was abolished when the NHE inhibitors amiloride and HOE642 and the Na+/K+-ATPase inhibitor, ouabain, were used. Our studies also showed that extracellular alkalosis (pH 8.5) induced MAPKAPK2 phosphorylation (2.59-fold, 2 min) and HSP27 phosphorylation (5.33-fold, 2 min) in a p38-MAPK-dependent manner, as it was inhibited with 1 μmol l–1 SB203580. Furthermore,immunohistochemical studies of the phosphorylated forms of p38-MAPK and HSP27 revealed that these proteins were localised in the perinuclear region and dispersedly in the cytoplasm of ventricular cells during alkalosis. Finally,alkalosis induced the increase of HSP70 protein levels (1.52-fold, 5 min), but independently of p38-MAPK activation. These data indicate that the p38-MAPK signalling pathway is activated by extracellular pH changes and in the case of alkalosis this activation may have a protective role.
Kinematics of foraging dives and lunge-feeding in fin whales
Authors: Goldbogen Jeremy A. , Calambokidis John , Shadwick Robert E. , Oleson Erin M. , McDonald Mark A. , Hildebrand John A. 
Published: March 2006

SUMMARYFin whales are among the largest predators on earth, yet little is known about their foraging behavior at depth. These whales obtain their prey by lunge-feeding, an extraordinary biomechanical event where large amounts of water and prey are engulfed and filtered. This process entails a high energetic cost that effectively decreases dive duration and increases post-dive recovery time. To examine the body mechanics of fin whales during foraging dives we attached high-resolution digital tags, equipped with a hydrophone, a depth gauge and a dual-axis accelerometer, to the backs of surfacing fin whales in the Southern California Bight. Body pitch and roll were estimated by changes in static gravitational acceleration detected by orthogonal axes of the accelerometer, while higher frequency, smaller amplitude oscillations in the accelerometer signals were interpreted as bouts of active fluking. Instantaneous velocity of the whale was determined from the magnitude of turbulent flow noise measured by the hydrophone and confirmed by kinematic analysis. Fin whales employed gliding gaits during descent, executed a series of lunges at depth and ascended to the surface by steady fluking. Our examination of body kinematics at depth reveals variable lunge-feeding behavior in the context of distinct kinematic modes, which exhibit temporal coordination of rotational torques with translational accelerations. Maximum swimming speeds during lunges match previous estimates of the flow-induced pressure needed to completely expand the buccal cavity during feeding.
Enhanced Discrimination of Benign from Malignant Prostatic Disease by Selective Measurements of Cleaved Forms of Urokinase Receptor in Serum
Authors: Piironen Timo , Haese Alexander , Huland Hartwig , Steuber Thomas , Christensen Ib Jarle , Brünner Nils , Danø Keld , Høyer-Hansen Gunilla , Lilja Hans 
Published: March 2006

AbstractBackground: Early detection of prostate cancer (PCa) centers on measurements of prostate-specific antigen (PSA), but current testing practices suffer from lack of specificity and generate many unnecessary prostate biopsies. Soluble urokinase plasminogen activator receptor (uPAR) is present in blood in both intact and cleaved forms. Increased uPAR in blood is correlated with poor prognosis in various cancers, but uPAR has not been shown to be useful in PCa diagnostics. We assessed the ability of immunoassays for specific uPAR forms to discriminate PCa from benign conditions.Methods: We measured total PSA (tPSA), free PSA (fPSA), intact uPAR [uPAR(I-III)], intact uPAR + cleaved uPAR domains II+III [uPAR(I-III) + uPAR(II-III)], and cleaved uPAR domain I [uPAR(I)] in sera from 224 men with and 166 men without PCa. We assessed differences in serum concentrations between the PCa and noncancer groups within the entire cohort and in men with tPSA concentrations of 2–10 μg/L. The diagnostic accuracy of individual analytes and analyte combinations was explored by logistic regression and ROC analyses and evaluations of sensitivity and specificity pairs.Results: Serum uPAR(I) and uPAR(II-III) were higher in PCa than in benign disease. In men with tPSA between 2 and 10 μg/L, the combination of %fPSA with the ratio uPAR(I)/uPAR(I-III) had a greater area under the ROC curve (0.73) than did %fPSA (0.68).Conclusions: Specific measurements of different uPAR forms in serum improve the specificity of PCa detection. The uPAR forms may therefore be complementary to PSA for PCa detection, most importantly in men with moderately increased PSA.
The Antibody Configurations of Cardiac Troponin I Assays May Determine Their Clinical Performance
Authors: James Stefan , Flodin Mats , Johnston Nina , Lindahl Bertil , Venge Per 
Published: March 2006

Abstract
Background: Previous studies have shown superior clinical performance of the cardiac troponin I (cTnI) assay from Beckman-Coulter Diagnostics. This assay had a unique combination of monoclonal antibodies with 2 monoclonal antibodies directed against epitopes near the NH2 terminus of the heart-specific region of troponin I. The approach has been adopted by the new cTnI assay from Abbott Diagnostics. The aim of our study was to investigate whether this approach affects the clinical performance of cTnI assays.
Methods: Cardiac troponin concentrations were measured in a random sample of patients with unstable coronary artery disease included in the GUSTO IV trial (n = 696) by the AccuTnI (Beckman-Coulter Diagnostics), Architect cTnI (Abbott Diagnostics), Immulite 2500 cTnI (Diagnostics Products Corporation), and Elecsys 2010 cTnT (Roche Diagnostics) assays and related to the 1-year mortality. The primary cutoff concentrations were based on the 99th percentile upper reference limits and an imprecision (CV) ≤10%.
Results: The sensitivities of the AccuTnI and Architect cTnI assays in identifying patients who died within 1 year were equal and were significantly higher (P &lt;0.05) than those of the Immulite 2500 cTnI and the Elecsys cTnT assays. The concordance between the AccuTnI and Architect cTnI assays was 97%, but concordances between the Architect cTnI and the Elecsys cTnT assays were 89%–92% with more at-risk patients (P &lt;0.01 to P &lt;0.001) identified by the Architect cTnI assay.
Conclusions: The Architect cTnI assay has clinical performance similar to that of the AccuTnI, probably as a result of the inclusion of a monoclonal antibody against troponin I epitope 41–49 in the assay.
Rec A-independent homologous recombination induced by a putative fold-back tetraplex DNA
Authors: Shukla Arun Kumar , Roy Kunal B. 
Published: March 2006

AbstractWe have recently reported that a GC-rich palindromic repeat sequence presumably adopts a stable fold-back tetraplex DNA structure under supercoiling. To establish the biological significance of this structure, we inserted this sequence between two direct repeat sequences, separated by 200 bp, in a plasmid. We then investigated the effect of this sequence on homologous recombination events. Here we report that the putative fold-back DNA tetraplex structure induces homologous recombination between direct repeat sequences. Interestingly, this recombination event is independent of recA, a major driving force for homologous recombination. We think that the fold-back structure forces the repeat sequences to come into close proximity and therefore leads to strand exchange. Although triplex-induced recombination has been well documented, our results for the first time directly establish the potential of a tetraplex structure to induce recA-independent homologous recombinationin vivo. This finding might have a significant implication for site-directed gene deletion in the context of the correction of genetic defects.
Pressure- and temperature-induced unfolding studies: thermodynamics of core hydrophobicity and packing of ribonuclease A
Authors: Font Josep , Benito Antoni , Torrent Joan , Lange Reinhard , Ribó Marc , Vilanova Maria 
Published: March 2006

AbstractIn this work we demonstrate that heat and pressure induce only slightly different energetic changes in the unfolded state of RNase A. Using pressure and temperature as denaturants on a significant number of variants, and by determining the free energy of unfolding at different temperatures, we estimated the stability of variants unable to complete the unfolding transition owing to the experimental conditions required for pressure experiments. The overall set of results allowed us to map the contributions to stability of the hydrophobic core residues of RNase A, with the positions most critical for stability being V54, V57, I106 and V108. We also show that the stability differences can be attributed to both hydrophobic interactions and packing density with an equivalent energetic magnitude. The main hydrophobic core of RNase A is tightly packed, as shown by the small-to-large and isosteric substitutions. In addition, we found that large changes in the number of methylene groups have non-additive positive stability interaction energies that are consistent with exquisite tight core packing and rearrangements of van der Waals' interactions in the protein interior, even after drastic deleterious substitutions.
The Development of Procedures for Charpy Impact Testing
Authors: Siewert TA , McCowan CN 
Published: March 2006

AbstractThis paper provides a broad overview of the progress in procedural improvements for Charpy impact testing. It includes a short summary of early developments, a discussion of topics that have been the subject of recent research, and a description of the importance of direct and indirect verification procedures. The need for standard procedures was recognized soon after the test was developed, and the early discoveries help to build the framework for our current procedures. Nevertheless, even after all these years of procedure development, researchers still find the need to learn more about certain aspects of the test procedures. Recent research seems to be concentrated in several broad categories: properties of the specimen (e.g., surface finish, tolerances, and miniature sizes for special applications), the anvils and striker (e.g., radii and surface finish), and general test procedures (e.g., time to reach test temperature and suitability for cryogenic testing).
Influence of Cold Rolling Threads Before or After Heat Treatment on the Fatigue Resistance of High Strength Fine Thread Bolts for Multiple Preload Conditions
Authors: Bradley NJ , Stephens RI , Horn NJ , Gradman JJ , Arkema JM , Borgwardt CS 
Published: March 2006

Abstract
SI class 12.9 high strength steel bolts were used to investigate the fatigue behavior of bolt threads rolled before/after heat treatment at five different preload values. Bolts used were 3/8 UNRF-24 (fine) and preloads were taken as 1, 50, 75, 90, and 100 % of roll before heat treatment proof stress. Since proof stress was lowered 10 % for roll after heat treatment, these preloads for roll after heat treatment bolts were then actually 1.1, 55, 83, 100, and 110 % of proof stress (to keep load the same). The tests produced a range of R ratios (R=Smin/Smax) between 0.03 and 0.92. Maximum near surface residual compressive stresses, obtained via x-ray diffraction, ranged from −500 to −1000 MPa. Axial loads were applied through the nut and all fatigue failures occurred at the first thread of the nut/bolt interface with crescent shaped cracks dominating in most tests. Multiple ratchet marks (separate crack nucleation sites) occurred for roll before heat treatment bolts, while fewer or no ratchet marks, were evident for the roll after heat treatment. Scanning electron microscopy evaluation indicated all fatigue crack growth regions contained multiple fatigue facets, while final fracture regions contained ductile dimpling. Cyclic creep/ratcheting was monitored and little, or none, was observed for preload tests equal to or less than 75 %. Replication data indicated a log-normal distribution on life was very reasonable. The fatigue resistance for fine threads rolled after heat treatment with preload stresses of 1 % (R ratio less than 0.05) caused very large increases (158 %) in 107 cycles fatigue strength compared to roll before heat treatment. This is in agreement with other roll before/after low R-ratio results. The roll after heat treatment bolts when tested at the higher proof loads had 107 fatigue strengths of 69 to 30 % increase. These increases are much less than the 158 % at 1 % preload, but still significant. Constant life Haigh diagrams at 105 and 107 cycles were in qualitative agreement with VDI 2230 bolt preload guidelines.
Promoted Combustion Testing of Pure and Ceramic-Coated Metals in High Pressure Oxygen by the Federal Institute of Materials Research and Testing (BAM)
Authors: Binder C , Kasch T , Brock T , Beck U , Weise M , Share M 
Published: March 2006

Abstract
The new promoted ignition combustion test apparatus at BAM matches the requirements of ASTM test method G 124 [ASTM G 124, Standard Test Method for Determining the Combustion Behavior of Metallic Materials in Oxygen-Enriched Atmospheres, 2003] and of EIGA publication, IGC Doc 13/02/E [EIGA Gas Association Document IGC Doc 13/02/E, Oxygen Pipeline Systems, 2003]. The test apparatus is most likely the only one in Europe. The test chamber allows investigations with pure oxygen or oxygen mixtures at pressures up to 500 bar and at temperatures up to 400°C at static or flowing gas conditions. The ignition device consists of an electrical ignition wire and a promoter. IR-sensors, distributed over the whole length of the rod, measure and record the burning temperature and allow measurement of the burn rate. A video system records the experiment for visual characterization of the burning behavior. BAM test results are compared with published data. Results on investigations with coated rods are presented. Ceramic coatings seem to be a solution for the use of certain less compatible metallic materials at higher oxygen pressures.
Mechanical Impact of Aluminum Alloy Gas Cylinder Pressurized with Oxygen
Authors: Chiffoleau G , Newton B , Holroyd NJH , Havercroft S 
Published: March 2006

AbstractOver the past 30 years a handful of fires in medical oxygen high pressure gas storage systems involving aluminum alloy cylinders have been deemed to be associated with mechanical impact-induced ignition of a contaminated system. For example, hydrocarbon contamination and mechanical impact promoted by being dropped during transportation. While the number of these incidents is minuscule compared to the number of systems used in the field, the effect is significant when such an ignition occurs. The kindling chain and initial ignition point of these fires, however, is poorly understood. Although made from more oxygen compatible metallic materials, the cylinder valves attached to these aluminum cylinders contain nonmetallic materials and are in direct contact with the cylinder threads, which are the thinnest cross section of the cylinder. A mechanical impact test was developed to investigate the conditions required to cause ignition of a cylinder and valve assembly by this ignition mechanism, with and without a wide range of controlled contaminants. Specially prepared small cylinders were assembled with commonly used brass cylinder valves and positioned under a drop tower capable of delivering energies up to 434 J (320 ft·lb). Cylinder assemblies were tested with various orientation and impact points including the cylinder valves and no ignitions were recorded in a total of 23 tests.
Proficiency Testing for Evaluating Aerospace Materials Test Anomalies
Authors: Hirsch D , Motto S , Peyton G , Beeson H 
Published: March 2006

Abstract
ASTM G 86 “Standard Test Method for Determining Ignition Sensitivity of Materials to Mechanical Impact in Ambient Pressure Liquid Oxygen and Pressurized Liquid and Gaseous Oxygen” and ASTM G 74 “Standard Test Method for Ignition Sensitivity of Materials to Gaseous Fluid Impact” are commonly used to evaluate materials susceptibility to ignition in liquid and gaseous oxygen systems. However, the methods have been known for their lack of repeatability. The inherent problems identified with the test logic would either not allow precise identification or the magnitude of problems related to running the tests, such as lack of consistency of systems performance, lack of adherence to procedures, etc. Excessive variability leads to increasing instances of accepting the null hypothesis erroneously, and so to the false logical deduction that problems are nonexistent when they really do exist. This paper attempts to develop and recommend an approach that could lead to increased accuracy in problem diagnostics by using the 50 % reactivity point, which has been shown to be more repeatable. The initial tests conducted indicate that PTFE and Viton® A5 (for pneumatic impact) and Buna S (for mechanical impact) would be good choices for additional testing and consideration for interlaboratory evaluations. The approach presented could also be used to evaluate variable effects with increased confidence and tolerance optimization.
Strain Control During High Speed Tensile Testing
Authors: Choi I , Lee S , Matlock DK , Speer JG 
Published: March 2006

Abstract
Mechanical properties of transition-induced plasticity steels depend on the possible variations in the complex microstructures, such as the shape, volume fraction, stability, and chemical composition of retained austenite. The effect of retained austenite stability on martensitic transformation is important, and can be evaluated in low strain rate testing conditions by stopping the deformation during testing. However, it is much more difficult to stop the test during a high speed dynamic tensile test. Hence, it was necessary to develop a method to stop a test during high speed deformation. An instrument was designed to attach to the sample to limit the strain during high speed tensile test and the applicability of the system was evaluated over the strain rate range of 10−2 to 102 s−1. This instrument was found to be successful in allowing controlled amounts of tensile strain to be imparted to a specimen under dynamic test conditions.
Surface Roughness Measurement Using Laser Speckle Statistical Analysis
Authors: Seif MA , Rawwash M 
Published: March 2006

Abstract
This work represents a noncontact nondestructive technique for surface roughness measurement. The technique is based on investigating the statistical properties of the speckle patterns that are developed whenever a surface is illuminated with a highly coherent light source such as a laser. The main objective is to correlate the sizes of the speckles with their light intensities to the surface roughness and profile. Different statistical approaches and correlation analysis have been implemented. Spatial data analysis, or variogram analysis, has been used to develop the relationship between observations taken at various locations. Among the other advantages of such an approach, this technique is simple to implement and suitable for operation in a manufacturing environment.