bluuebunny/crossref_metadata_2025 huggingface dataset:
Load tests on bedrock
Authors: Seychuk J. L.
Published: October 2008

Load tests involving the use of a steel plate, a concrete socket, and full scale concrete piles were carried out at two separate sites in Ontario to determine the load bearing characteristics of shale and limestone bedrock. It was found that the essentially sound bedrock behaved as an elastic material under the maximum applied pressure of 260 tons/sq. ft (254 × 104 kg/m2). In addition to the vertical load tests on the rock, a lateral pile load test was carried out to evaluate the modulus of horizontal subgrade reaction of the fissured clay overburden at one of the sites.
Pulling capacity of concrete cast in situ bored piles
Authors: Sowa V. A.
Published: October 2008

The pulling capacity of cylindrical concrete piles cast in situ in bored holes is examined for piles constructed in sandy or cohesive soils. On the basis of the data presented, it is concluded that the pulling capacity of these piles in cohesive soils can be estimated approximately, while the pulling capacity of piles in sandy soil is considerably more difficult to estimate. Estimating the pulling capacity of piles in cohesive soils is based on an empirical relationship between soil adhesion and the undrained shear strength. A possible explanation for the difficulty in estimating the pulling capacity of piles in sandy soils is suggested.
Coal in a carbonate sequence stratigraphic framework: the Upper Permian Heshan Formation in central Guangxi, southern China
Authors: Shao Longyi , Zhang Pengfei , Gayer R.A. , Chen Jialiang , Dai Shifeng
Published: October 2008

Microfacies and sedimentological analyses of the Upper Permian coal-bearing Heshan Formation in the Heshan coalfield of central Guangxi suggest that these coal measures formed in a marine carbonate platform setting. Low-volatile bituminous coals with very high organic sulphur overlie either palaeosols or locally developed cherts. The petrography and geochemistry of the coals suggest formation in low-lying mires, in which marine influence increased upwards. In the Heshan and overlying Dalong Formations, four third-order sequences are described based on the recognition of four sequence boundaries. Higher-order sequences within each of these third-order sequences are also documented and, within Sequence III, coal seams are developed above higher-order transgressive surfaces, representing the deposits formed during the lag time between initial flooding of the platform and the onset of carbonate production. In the Heshan Formation, the coals with greatest thickness occur immediately above third-order transgressive surfaces. It is argued that, in some coal-bearing siliciclastic-free marine carbonate-platform settings, accommodation creation rates and peat accumulation rates are balanced, hence greater coal accumulation can be achieved at the transgressive surface rather than at the maximum flooding surface.
Carbonate formations and early NW-directed thrusting in the highest allochthons of the Norwegian Caledonides: evidence of a Laurentian ancestry
Authors: ROBERTS D. , MELEZHIK V. M. , HELDAL T.
Published: October 2008

tructural, sedimentological and isotope-geochemical investigations on thick, carbonate formations in the Uppermost Allochthon of the Norwegian Caledonides have provided the first direct indications of the Laurentian origins of these shelf and slope/rise successions. Chemostratigraphical ages for marbles mostly range from Vendian to Cambrian. The earliest tectonic deformation, involving NW-vergent thrusts and folds in one of the nappes, is considered to relate to Taconian orogenic development along the margin of Laurentia. Subsequently, during Siluro-Devonian, Baltica–Laurentia collision, these thick successions, and plutonic complexes farther south, were detached from their Laurentian roots and retransported into the higher levels of the Scandian orogenic wedge.
Provenance of the Moine Supergroup of NW Scotland: evidence from geochronology of detrital and inherited zircons from (meta)sedimentary rocks, granites and migmatites
Authors: Friend C.R.L. , Strachan R.A. , Kinny P.D. , Watt G.R.
Published: October 2008

Detrital and inherited zircons from rocks of the Moine Supergroup from structural and stratigraphic positions above and below the Sgurr Beag and Naver thrusts have been dated by ion microprobe.
207
Pb/
206
Pb ages for 65 detrital zircons from the Moine Nappe (Morar Group) range between 2707 and 947 Ma, with a bimodal distribution with clusters at
c
. 1650 and 1400 Ma. Five grains (8% of the analyses) were Archaean. Analyses of 97 inherited zircons from two Caledonian migmatites and two granites from the Naver Nappe yield
207
Pb/
206
Pb ages between
c
. 2940 and 926 Ma. They have a dominant cluster at
c
. 1650 Ma with significant clusters at c. 1400 and
c
. 1050 Ma. Eight Archaean grains were discovered (8.5% of analyses). Three rocks above the Sgurr Beag Thrust have been examined and a total of 42 analyses obtained.
207
Pb/
206
Pb ages for 35 inherited zircons from two outcrops of the essentially
in situ
West Highland granite gneiss within the Glenfinnan and Loch Eil Groups range from
c
. 1889 to 947 Ma. A sample of the Lochailort pelite provided a further seven detrital analyses. These data have a distribution with clusters at
c
. 1500 and 1100 Ma. The combined datasets indicate that the Moine Supergroup was deposited in a post-Grenvillian basin(s) with detritus derived predominantly from a late Palaeoproterozoic source, e.g. Gothian or Labradorian with only a very small proportion from older sources. The data indicate that the Naver and Sgurr Beag nappes had different sediment sources and so may not correlate. The Morar Group is dominated by late Palaeoproterozoic detritus with lesser amounts of Grenville-aged detritus. The Glenfinnan and Loch Eil Groups appear to have roughly equal proportions of detritus from the two sources. The few Archaean grains indicate that the source comprised comparatively little material of this age, precluding the Lewisian Complex or sub-Moine basement as a significant source and arguing against correlation of the Moine with the Torridonian.
The origin and significance of the Delaney Dome Formation, Connemara, Ireland
Authors: DRAUT AMY E. , CLIFT PETER D.
Published: October 2008

Dalradian meta-sediments of the Laurentian margin and mafic intrusions thereof in SW Connemara, Ireland, tectonically overlie meta-rhyolites of the Delaney Dome Formation. The two units are separated by the Mannin Thrust. A new U–Pb age of 474.6 ± 5.5 Ma shows that the Delaney Dome Formation is a temporal equivalent of arc volcanic rocks preserved in the adjacent South Mayo Trough: the Tourmakeady Volcanic Group, erupted during the collision of an oceanic island arc with the Laurentian margin in the Grampian Orogeny. New rare earth and high field strength element data show that the Delaney Dome Formation and Tourmakeady Volcanic Group are chemically similar and arc-like in character. This suggests that the Delaney Dome Formation is an along-strike equivalent of the Tourmakeady Group, strike-slip faulted south of the South Mayo Trough during or after the Grampian Orogeny. Further correlation of these units with northern Appalachian rhyolites is also possible. The Delaney Dome Formation is an extrusive temporal equivalent of intrusions that penetrate the Connemara Dalradian. Thus, movement along the Mannin Thrust brought mid-crustal plutons and Dalradian country rocks tectonically above the extrusive volcanic sequence. The Mannin Thrust is identified as a major imbricating structure within a continental arc, but not a terrane boundary.
Timing of deposition, orogenesis and glaciation within the Dalradian rocks of Scotland: constraints from U–Pb zircon ages
Authors: DEMPSTER T. J. , ROGERS G. , TANNER P. W. G. , BLUCK B. J. , MUIR R. J. , REDWOOD S. D. , IRELAND T. R. , PATERSON B. A.
Published: October 2008

Abstract: The stratigraphical and structural continuity of the Late Proterozoic Dalradian rocks of the Scottish Highlands is re-examined in the light of new U–Pb zircon ages on the tuffs belonging to the Tayvallich Volcanic Formation (601 ± 4 Ma), and on the late Grampian ‘Newer Gabbros’ (470 ± 9 Ma) of Insch and Morven–Cabrach in Aberdeenshire. These age data, together with the existing 590 ± 2 Ma age for the Ben Vuirich Granite, provide key radiometric constraints on the evolution of the Dalradian block, and the implications arising from these ages are critically assessed. Three main conclusions are drawn.

(1) The entire Caledonian orogeny, although short-lived, is unlikely to have affected sediments of Arenig age and a break probably occurs between those Dalradian sediments of late Proterozoic (<600 Ma) age and the Ordovician rocks of the Highland Border Complex.

(2) A period of crustal thickening probably affected some Dalradian rocks prior to 590 Ma. Such an event is indicated by both the polymetamorphic histories of the lower parts of the Dalradian pile and the contact metamorphic assemblages within the aureole of the Ben Vuirich Granite, which are incompatible with sedimentary thicknesses.

(3) Age constraints on global Late Proterozoic glacial activity also suggest that the Dalradian stratigraphy is broken into discrete smaller units. Models involving continuous deposition of Dalradian sediments from pre-750 Ma to 470 Ma are rejected.
Impaired cerebral autoregulation in obstructive sleep apnea
Authors: Urbano Fred , Roux Francoise , Schindler Joseph , Mohsenin Vahid
Published: October 2008

Obstructive sleep apnea (OSA) increases the risk of stroke independent of known vascular and metabolic risk factors. Although patients with OSA have higher prevalence of hypertension and evidence of hypercoagulability, the mechanism of this increased risk is unknown. Obstructive apnea events are associated with surges in blood pressure, hypercapnia, and fluctuations in cerebral blood flow. These perturbations can adversely affect the cerebral circulation. We hypothesized that patients with OSA have impaired cerebral autoregulation, which may contribute to the increased risk of cerebral ischemia and stroke. We examined cerebral autoregulation in patients with and without OSA by measuring cerebral artery blood flow velocity (CBFV) by using transcranial Doppler ultrasound and arterial blood pressure using finger pulse photoplethysmography during orthostatic hypotension and recovery as well as during 5% CO2 inhalation. Cerebral vascular conductance and reactivity were determined. Forty-eight subjects, 26 controls (age 41.0±2.3 yr) and 22 OSA (age 46.8±2.3 yr) free of cerebrovascular and active coronary artery disease participated in this study. OSA patients had a mean apnea-hypopnea index of 78.4±7.1 vs. 1.8±0.3 events/h in controls. The oxygen saturation during sleep was significantly lower in the OSA group (78±2%) vs. 91±1% in controls. The dynamic vascular analysis showed mean CBFV was significantly lower in OSA patients compared with controls (48±3 vs. 55±2 cm/s; P <0.05, respectively). The OSA group had a lower rate of recovery of cerebrovascular conductance for a given drop in blood pressure compared with controls (0.06±0.02 vs. 0.20±0.06 cm·s−2·mmHg−1; P <0.05). There was no difference in cerebrovascular vasodilatation in response to CO2. The findings showed that patients with OSA have decreased CBFV at baseline and delayed cerebrovascular compensatory response to changes in blood pressure but not to CO2. These perturbations may increase the risk of cerebral ischemia during obstructive apnea.
Single-Stage Correction of Urinary Incontinence and Vaginoplasty in a Case of Urethral Coitus with Vaginal Agenesis
Authors: Khattar Nikhil , Dorairajan L.N. , Kumar Santosh , Soundararaghavan S. , Pal Bipin Chandra
Published: October 2008

Urethral coitus is a very rare entity which usually presents as urethral incontinence during intercourse and is most commonly seen with intact vagina. Only about 24 cases have been reported in the literature. A presentation in vaginal agenesis is exceedingly rare and poses the surgical challenge of restoring continence without interfering with sex life. Here we report a case of urethral intercourse with vaginal agenesis presenting with incontinence that we treated with McIndoe’s vaginoplasty and urethral plication in a single stage, with satisfactory result. To the best of our knowledge, this method of reconstruction has not yet been reported for this condition.
PIAS1 Mediates TGFβ-Induced SM α-Actin Gene Expression Through Inhibition of KLF4 Function-Expression by Protein Sumoylation
Authors: Kawai-Kowase Keiko , Ohshima Takayuki , Matsui Hiroki , Tanaka Toru , Shimizu Takehisa , Iso Tatsuya , Arai Masashi , Owens Gary K. , Kurabayashi Masahiko
Published: October 2008

Objective—

TGFβ and proliferation/phenotypic switching of smooth muscle cells (SMCs) play a pivotal role in pathogenesis of atherosclerotic and restenotic lesions after angioplasty. We have previously shown that the protein inhibitor of activated STAT (PIAS)1 activates expression of SMC differentiation marker genes including smooth muscle (SM) α-actin by interacting with serum response factor (SRF) and class I bHLH proteins. Here, we tested the hypothesis that TGFβ activates SM α-actin through PIAS1.

Methods and Results—

An siRNA specific for PIAS1 and ubc9, an E2-ligase for sumoylation, inhibited TGFβ-induced expression of SM α-actin in cultured SMCs as determined by real-time RT-PCR. Overexpression of PIAS1 increased SM α-actin promoter activity in a TGFβ control element (TCE)-dependent manner. Because the TCE within the SM α-actin promoter could mediate repression through interaction with KLF4, we tested whether PIAS1 regulates the function of KLF4 for SMC gene expression. PIAS1 interacted with KLF4 in mammalian two-hybrid and coimmunoprecipitation assays, and overexpression of PIAS1 inhibited KLF4-repression of SM α-actin promoter activity. Moreover, PIAS1 promoted degradation of KLF4 through sumoylation.

Conclusions—

These results provide evidence that PIAS1 promotes TGFβ-induced activation of SM α-actin gene expression at least in part by promoting sumoylation and degradation of the TCE repressor protein, KLF4.
Accelerating Event-Driven Simulation of Spiking Neurons with Multiple Synaptic Time Constants
Authors: D'Haene Michiel , Schrauwen Benjamin , Van Campenhout Jan , Stroobandt Dirk
Published: October 2008

The simulation of spiking neural networks (SNNs) is known to be a very time-consuming task. This limits the size of SNN that can be simulated in reasonable time or forces users to overly limit the complexity of the neuron models. This is one of the driving forces behind much of the recent research on event-driven simulation strategies. Although event-driven simulation allows precise and efficient simulation of certain spiking neuron models, it is not straightforward to generalize the technique to more complex neuron models, mostly because the firing time of these neuron models is computationally expensive to evaluate. Most solutions proposed in literature concentrate on algorithms that can solve this problem efficiently. However, these solutions do not scale well when more state variables are involved in the neuron model, which is, for example, the case when multiple synaptic time constants for each neuron are used. In this letter, we show that an exact prediction of the firing time is not required in order to guarantee exact simulation results. Several techniques are presented that try to do the least possible amount of work to predict the firing times. We propose an elegant algorithm for the simulation of leaky integrate-and-fire (LIF) neurons with an arbitrary number of (unconstrained) synaptic time constants, which is able to combine these algorithmic techniques efficiently, resulting in very high simulation speed. Moreover, our algorithm is highly independent of the complexity (i.e., number of synaptic time constants) of the underlying neuron model.
Parallel Hopfield Networks
Authors: Wilson Robert C.
Published: October 2008

We introduce a novel type of neural network, termed the parallel Hopfield network, that can simultaneously effect the dynamics of many different, independent Hopfield networks in parallel in the same piece of neural hardware. Numerically we find that under certain conditions, each Hopfield subnetwork has a finite memory capacity approaching that of the equivalent isolated attractor network, while a simple signal-to-noise analysis sheds qualitative, and some quantitative, insight into the workings (and failures) of the system.
Adaptive Improved Natural Gradient Algorithm for Blind Source Separation
Authors: Liu Jian-Qiang , Feng Da-Zheng , Zhang Wei-Wei
Published: October 2008

We propose an adaptive improved natural gradient algorithm for blind separation of independent sources. First, inspired by the well-known backpropagation algorithm, we incorporate a momentum term into the natural gradient learning process to accelerate the convergence rate and improve the stability. Then an estimation function for the adaptation of the separation model is obtained to adaptively control a step-size parameter and a momentum factor. The proposed natural gradient algorithm with variable step-size parameter and variable momentum factor is therefore particularly well suited to blind source separation in a time-varying environment, such as an abruptly changing mixing matrix or signal power. The expected improvement in the convergence speed, stability, and tracking ability of the proposed algorithm is demonstrated by extensive simulation results in both time-invariant and time-varying environments. The ability of the proposed algorithm to separate extremely weak or badly scaled sources is also verified. In addition, simulation results show that the proposed algorithm is suitable for separating mixtures of many sources (e.g., the number of sources is 10) in the complete case.
Pharmacokinetics of Novel Atrial‐Selective Antiarrhythmic Agent Vernakalant Hydrochloride Injection (RSD1235): Influence of CYP2D6 Expression and Other Factors
Authors: Mao Zhongping L. , Wheeler Jeffery J. , Clohs Lilian , Beatch Gregory N. , Keirns James
Published: October 2008

Vernakalant hydrochloride injection (RSD1235) is a relatively atrial‐selective antiarrhythmic agent that converts atrial fibrillation rapidly to sinus rhythm. The pharmacokinetics of vernakalant were explored in healthy volunteers and in patients with atrial fibrillation or atrial flutter in 4 clinical studies. Key pharmacokinetic parameters analyzed were the maximum plasma concentration and the area under the plasma concentration—time curve. Vernakalant exhibited linear pharmacokinetics over the dose range of 0.1 mg/kg to 5.0 mg/kg in healthy subjects, and generally showed dose proportionality in patients with atrial fibrillation or atrial flutter who received 1 or 2 vernakalant infusions. Vernakalant was metabolized rapidly via 4‐O‐demethylation by cytochrome P450 (CYP)2D6 to its major metabolite RSD1385, which then circulated predominantly as an inactive glucuronide conjugate. In most patients, the maximum plasma concentration of RSD1385 glucuronide exceeded that of vernakalant. Unconjugated RSD1385 was found at low levels in all patients demonstrating either a cytochrome P450 CYP2D6 “extensive metabolizer” or “poor metabolizer” phenotype or genotype; however, CYP2D6 poor metabolizers had even lower levels of unconjugated RSD1385. The impact of CYP2D6 metabolizer status on vernakalant exposure was explored in patients with atrial fibrillation or atrial flutter who received a therapeutic regimen (3 mg/kg initially via 10‐minute intravenous infusion followed by a second 2 mg/kg 10‐minute infusion if atrial fibrillation persisted after a 15‐minute observation period). In the subset that received 2 vernakalant infusions, there was little difference in vernakalant maximum plasma concentration or area under the plasma concentration—time curve from the start of the first infusion to 90 minutes between CYP2D6 poor metabolizers and extensive metabolizers or between those who did or did not receive concomitant CYP2D6‐inhibitor medications. Gender, age, and renal function did not have a clinically significant influence on the pharmacokinetics of vernakalant. These results suggest that an assessment of CYP2D6 expression may not be needed when vernakalant is administered acutely and intravenously to patients with atrial fibrillation.
Dusp-5 and Snrk-1 coordinately function during vascular development and disease
Authors: Pramanik Kallal , Chun Chang Zoon , Garnaas Maija K. , Samant Ganesh V. , Li Keguo , Horswill Mark A. , North Paula E. , Ramchandran Ramani
Published: October 2008

Mitogen-activated protein kinases play an integral role in several cellular processes. To regulate mitogen-activated protein kinases, cells express members of a counteracting group of proteins called phosphatases. In this study, we have identified a specific role that one member of this family of phosphatases, dual-specific phosphatase-5 (Dusp-5) plays in vascular development in vivo. We have determined that dusp-5 is expressed in angioblasts and in established vasculature and that it counteracts the function of a serine threonine kinase, Snrk-1, which also plays a functional role in angioblast development. Together, Dusp-5 and Snrk-1 control angioblast populations in the lateral plate mesoderm with Dusp-5 functioning downstream of Snrk-1. Importantly, mutations in dusp-5 and snrk-1 have been identified in affected tissues of patients with vascular anomalies, implicating the Snrk-1–Dusp-5 signaling pathway in human disease.
A novel screening protocol for the isolation of hydrogen producing Chlamydomonas reinhardtiistrains
Authors: Rühle Thilo , Hemschemeier Anja , Melis Anastasios , Happe Thomas
Published: October 2008

Background

Sealed Chlamydomonas reinhardtii cultures evolve significant amounts of hydrogen gas under conditions of sulfur depletion. However, the eukaryotic green alga goes through drastic metabolic changes during this nutritional stress resulting in cell growth inhibition and eventually cell death. This study aimed at isolating C. reinhardtii transformants which produce hydrogen under normal growth conditions to allow a continuous hydrogen metabolism without the stressful impact of nutrient deprivation.

Results

To achieve a steady photobiological hydrogen production, a screening protocol was designed to identify C. reinhardtii DNA insertional mutagenesis transformants with an attenuated photosynthesis to respiration capacity ratio (P/R ratio). The screening protocol entails a new and fast method for mutant strain selection altered in their oxygen production/consumption balance. Out of 9000 transformants, four strains with P/R ratios varying from virtually zero to three were isolated. Strain apr1 was found to have a slightly higher respiration rate and a significantly lower photosynthesis rate than the wild type. Sealed cultures of apr1 became anaerobic in normal growth medium (TAP) under moderate light conditions and induced [FeFe]-hydrogenase activity, yet without significant hydrogen gas evolution. However, Calvin-Benson cycle inactivation of anaerobically adapted apr1 cells in the light led to a 2-3-fold higher in vivo hydrogen production than previously reported for the sulfur-deprived C. reinhardtii wild type.

Conclusion

Attenuated P/R capacity ratio in microalgal mutants constitutes a platform for achieving steady state photobiological hydrogen production. Using this platform, algal hydrogen metabolism can be analyzed without applying nutritional stress. Furthermore, these strains promise to be useful for biotechnological hydrogen generation, since high in vivo hydrogen production rates are achievable under normal growth conditions, when the photosynthesis to respiration capacity ratio is lowered in parallel to down regulated assimilative pathways.
Characterization and Putative Role of a Type I Gonadotropin-Releasing Hormone in the Cephalochordate Amphioxus
Authors: Chambery Angela , Parente Augusto , Topo Enza , Garcia-Fernàndez Jordi , D'Aniello Salvatore
Published: October 2008

GnRH, originally isolated from mammalian hypothalamus, is a key player in the control of vertebrate reproduction. Employing reverse-phase chromatography, we purified a peptide of relative molecular mass of 1182.60 Da from the cephalochordate amphioxus Branchiostoma lanceolatum. We found that its amino acid sequence (pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2) was identical to that of mammalian GnRH. The highest concentrations (4.04 ± 0.3 μg/g tissue), localized in the anterior part of the body, occurred in November, a time when amphioxus gonads prepare for the seasonal spawning. Furthermore, the biological activity of amphioxus GnRH was investigated by examining its capability to elicit LH release from the rodent pituitary gland. The origins of GnRH can be traced back to the origins of chordates. The seasonal variations of amphioxus GnRH also suggest an ancient role of this peptide in the control of reproduction in chordates, even before the evolution of a proper pituitary gland.

Data show that the isolation of a GnRH hormone in the cephalochordate Amphioxus could have a pivotal role in reproduction.
Retinoic acid and Cyp26b1 are critical regulators of osteogenesis in the axial skeleton
Authors: Spoorendonk Kirsten M. , Peterson-Maduro Josi , Renn Jörg , Trowe Torsten , Kranenbarg Sander , Winkler Christoph , Schulte-Merker Stefan
Published: October 2008

Retinoic acid (RA) plays important roles in diverse biological processes ranging from germ cell specification to limb patterning. RA ultimately exerts its effect in the nucleus, but how RA levels are being generated and maintained locally is less clear. Here, we have analyzed the zebrafish stocksteif mutant, which exhibits severe over-ossification of the entire vertebral column. stocksteif encodes cyp26b1, a cytochrome P450 member that metabolizes RA. The mutant is completely phenocopied by treating 4 dpf wild-type embryos with either RA or the pharmacological Cyp26 blocker R115866, thus identifying a previously unappreciated role for RA and cyp26b1 in osteogenesis of the vertebral column. Cyp26b1 is expressed within osteoblast cells,demonstrating that RA levels within these cells need to be tightly controlled. Furthermore, we have examined the effect of RA on osteoblasts in vivo. As numbers of osteoblasts do not change upon RA treatment, we suggest that RA causes increased activity of axial osteoblasts, ultimately resulting in defective skeletogenesis.
To break a coralline: mechanical constraints on the size and survival of a wave-swept seaweed
Authors: Martone Patrick T. , Denny Mark W.
Published: October 2008

Previous studies have hypothesized that wave-induced drag forces may constrain the size of intertidal organisms by dislodging or breaking organisms that exceed some critical dimension. In this study, we explored constraints on the size of the articulated coralline alga Calliarthron, which thrives in wave-exposed intertidal habitats. Its ability to survive depends critically upon its segmented morphology (calcified segments separated by flexible joints or `genicula'), which allows otherwise rigid fronds to bend and thereby reduce drag. However, bending also amplifies stress within genicula near the base of fronds. We quantified breakage of genicula in bending by applying known forces to fronds until they broke. Using a mathematical model, we demonstrate the mitigating effect of neighboring fronds on breakage and show that fronds growing within dense populations are no more likely to break in bending than in tension, suggesting that genicular morphology approaches an engineering optimum, possibly reflecting adaptation to hydrodynamic stress. We measured drag in a re-circulating water flume(0.23–3.6 m s–1) and a gravity-accelerated water flume,which generates jets of water that mimic the impact of breaking waves(6–10 m s–1). We used frond Reynolds number to extrapolate drag coefficients in the field and to predict water velocities necessary to break fronds of given sizes. Laboratory data successfully predicted frond sizes found in the field, suggesting that, although Calliarthron is well adapted to resist breakage, wave forces may ultimately limit the size of intertidal fronds.
Hydrodynamics of the escape response in bluegill sunfish,Lepomis macrochirus
Authors: Tytell Eric D. , Lauder George V.
Published: October 2008

Escape responses of fishes are one of the best characterized vertebrate behaviors, with extensive previous research on both the neural control and biomechanics of startle response performance. However, very little is known about the hydrodynamics of escape responses, despite the fact that understanding fluid flow patterns during the escape is critical for evaluating how body movement transfers power to the fluid, for defining the time course of power generation, and for characterizing the wake signature left by escaping fishes, which may provide information to predators. In this paper, we present an experimental hydrodynamic analysis of the C-start escape response in bluegill sunfish (Lepomis macrochirus). We used time-resolved digital particle image velocimetry at 1000 frames s–1 (fps)to image flow patterns during the escape response. We analyzed flow patterns generated by the body separately from those generated by the dorsal and anal fins to assess the contribution of these median fins to escape momentum. Each escape response produced three distinct jets of fluid. Summing the components of fluid momentum in the jets provided an estimate of fish momentum that did not differ significantly from momentum measured from the escaping fish body. In contrast to conclusions drawn from previous kinematic analyses and theoretical models, the caudal fin generated momentum that opposes the escape during stage one, whereas the body bending during stage one contributed substantial propulsive momentum. Additionally, the dorsal and anal fins each contributed substantial momentum. The results underscore the importance of the dorsal and anal fins as propulsors and suggest that the size and placement of these fins may be a key determinant of fast start performance.
Pore-Water Pressure Buildup in Clean Sands Because of Cyclic Straining
Authors: Ladd RS , Dobry R , Dutko P , Yokel FY , Chung RM
Published: October 2008

The prediction of pore-water pressure buildup in sands caused by undrained cyclic loading is one of the key items in evaluating the potential for liquefaction of sandy sites during earthquakes. Presented herein are data indicating that, in strain-controlled tests, there is a predictable correlation between cyclic shear strain, number of cycles, and pore-water pressure buildup; this correlation is much less sensitive to factors, such as relative density and fabric than comparable results obtained from stress-controlled tests. Also, there is a threshold cyclic shear strain below which there is no sliding at the contacts between sand particles, and essentially no pore-water pressure buildup occurs. The data indicate that, for clean sands, this threshold shear strain, as well as the pore-water pressure buildup for strains slightly above the threshold, are basically independent of relative density, grain size distribution, fabric, and method of testing (triaxial and direct simple shear). However, both threshold shear strain and pore-water pressure buildup do depend on the overconsolidation ratio.
Laboratory Testing of Chemically Grouted Sand
Authors: Christopher BR , Atmatzidis DK , Krizek RJ
Published: October 2008

The effect of 14 parameters, associated with specimen preparation, handling, and testing, and with soil characteristics, was evaluated experimentally for laboratory prepared specimens of chemically grounted sands. Over 200 unconfined compression tests were conducted, and results are presented and comparisons are made in terms of unconfined compressive strength and tangent modulus at 50% of maximum stress. Curing environment, curing time, specimen size, grain size, and grain size distribution are the parameters that affect significantly the observed mechanical behavior of grouted sands. The results of this study were used in the development of ASTM Laboratory Preparation of Chemically Grouted Soil Specimens for Obtaining Design Strength Parameters (D 4320).
Hollow Cylinder Tests on Natural Rock Salt
Authors: Senseny PE , Mellegard KD , Wagner LA
Published: October 2008

Constitutive equations for the thermomechanical behavior of salt must accurately model material behavior when all three principal stresses are independent. Conventional triaxial compression and extension tests measure material response for stress states in which two of the principal stresses are equal. A computer-controlled, servohydraulic system is described for testing hollow cylinder specimens at stress states in which the principal stresses are controlled independently. Results of validation tests are given to show that the test system provides accurate measurements of the behavior of salt.
Studies with Centrifuge Vane and Penetrometer Apparatus in a Normal Gravity Field
Authors: Davies MCR , Almeida MSS , Parry RHG
Published: October 2008

Small vane and penetrometer devices have been developed to measure soil properties in models during centrifuge operation. To aid the interpretation of vane data from centrifuge models a series of tests was conducted in cakes of kaolin clay in a normal gravity field. In the experimental program the effects of disturbance during insertion, delay between insertion and rotation, rate of rotation and geometry of vane blades were investigated. The results were used to devise a scientific method of operation of the vane apparatus. Subsequent tests were all performed with a vane size of 18 mm diameter by 14 mm high. Penetrometer tests were conducted in cakes of kaolin and Gault clays. Vane shear strengths were used to calibrate the apparatus. The ratio of cone resistance to vane strength was found to increase with increasing over-consolidation ratio. The values also differed considerably between the two clays. Thus, while the penetrometer has the advantage of providing a continuous profile of resistance with depth, some care is required in converting this measurement into undrained shear strength.
Catching the Elusive Water-Cement Ratio Using Petrographic Methods—and Their Evaluation
Authors: Erlin Bernard
Published: October 2008

Petrographers use a variety of techniques for estimating the w/c and w/cm of hardened concrete. The estimates are routinely accepted by the concrete industry. Generally, four general methods are popular today: (1) water-droplet absorption; (2) scratch hardness; (3) combination of 12 or so microscopical and physical observations of the paste; and (4) methods where thin sections of concrete are impregnated with blue- or fluorescent-dyed epoxy. Sometimes combinations are used. There are few specific details in the literature for assessing the precision of the w/c using these methods except for the fluorescence technique, where there has been controversy about its claimed accuracy. The degree of interpretation of data from each method is based upon the comfort of petrographers in extending their expertise to provide that estimate. The deftness, skill, and experience of the petrographers will usually dictate their comfort zone. However, sometimes confounding that estimate is the existing concrete condition. The acceptability of the petrographic estimates depends on: (1) competency of the petrographer; (2) validity of the technique(s) used; (3) ability of the petrographer to qualify the techniques used; (4) the purpose(s) to which the data will be used; and (5) needs of those who either want to accept the estimates or debunk the estimates—for whatever reason.
Contribution of Thermodynamic Calculations to Metallurgical Studies of Multi-Component Zirconium Based Alloys
Authors: Toffolon-Masclet C. , Brachet J. C. , Servant C. , Joubert J. M. , Barberis P. , Dupin N. , Zeller P.
Published: October 2008

The Zircobase thermodynamic database for zirconium alloys coupled with Thermo-Calc software represents a powerful tool for prediction of thermodynamic and metallurgical data such as activities, formation enthalpies, phase transformation temperatures, solubility limits, existence temperature range, and chemical compositions of second phase precipitates. This database was built up with binary and ternary descriptions assessed according to the CALPHAD methodology. It is sometimes necessary to take into account new systems, but also new versions of binary descriptions as recently experienced. For example, the two binary systems Zr-Fe and Zr-Sn had to be updated in order to fit new experimental results believed to be more accurate than previously available.

This paper aims at showing the improvements of the database taking into account new descriptions of binary systems, as also ternary description such as Zr-Fe-Cr, Zr-Fe-Ni, and Zr-Nb-Fe. For this last ternary system, new experimental data were necessary. New experimental study of the two ternary phases, hexagonal Zr(Nb,Fe)2 and cubic (Zr,Nb)4Fe2, allowed their crystal structures (P63/mmc and Fd3¯m, respectively) to be checked. This was useful to build up a sublattice model giving account of the existence of a composition range for these two intermetallic phases. Moreover, several specific ZrNbFe alloys were fabricated and annealed for times ranging from 1000 h to 10,000 h at 550, 700, 800, and 900°C to determine the equilibrium binary and ternary phase domains as a function of the temperature. All these data were used to obtain an improved thermodynamic modelling of this system. Finally, we illustrate some thermodynamic predictions of the different phases evolutions as a function of the temperature on multi-alloyed industrial type alloys. These examples show quite good agreement between the thermodynamic predictions and the experimental data derived from calorimetric experiments and microstructural observations.
ZIRLOTM Cladding Improvement
Authors: Foster John Paul , Yueh H. Ken , Comstock Robert J.
Published: October 2008

Improvements to fuel design have been made in recent years to meet the challenges of increases in fuel duty in terms of linear power and operating temperature. Improved cladding material is one of these design improvements. Specifically, Westinghouse has developed an improved version of ZIRLOTM called Optimized ZIRLO and denoted as OPT ZIRLO. The Sn level in this improved material is reduced from the nominal standard previous level of about 1 % to a range of 0.6 % to 0.8 %. The reduced Sn level has been optimized to produce a higher corrosion resistance and provide adequate in-reactor creep resistance. Out-reactor diameter creep tests have shown that decreasing Sn increases out-reactor creep, suggesting that decreasing Sn may also increase in-reactor creep. An in-reactor testing program in the Vogtle Unit 2 pressurized water reactor (PWR) was performed to confirm the predicted in-reactor behavior. The test samples were suspended as segmented rods inside fuel assembly thimble tubes. In-reactor diameter creep data confirmed that decreasing Sn increases in-reactor creep. As a result of the correlation between in-reactor and out-reactor creep, an extensive out-reactor diameter creep program was performed in order to develop methods to fabricate OPT ZIRLO with the same in-reactor creep properties as the currently used stress-relief annealed standard ZIRLO (denoted as SRA STD ZIRLO). The level of in-reactor diameter creep of SRA STD ZIRLO was achieved for OPT ZIRLO by two methods. One method involved changing the final microstructure from SRA to partially recrystallized (PRXA). The other method kept the final microstructure as SRA and changed the tube reduction sequence to decrease the final tube area reduction. In order to develop these methods, a series of material variation tests was performed. Some of the material variations included different final heat treatments, different tube reduction sequences, and different pre-charged hydrogen levels. These tests were performed for both out-reactor and in-reactor. In addition, the out-reactor and in-reactor creep were observed to directly correlate for OPT ZIRLO material fabricated with different final anneal temperatures. Thus, out-reactor creep may be used to predict in-reactor creep properties for different final anneal temperatures. These results show that fabrication changes may be used to control in-reactor creep. In this study, fabrication changes were used to compensate for the reduction in in-reactor creep strength associated with lower tin content in OPT ZIRLO.
Computer Simulation of Consecutive Ski Turns
Authors: Mössner Martin , Heinrich Dieter , Kaps Peter , Schretter Herwig , Nachbauer Werner
Published: October 2008

A computer model was developed to simulate consecutive ski turns. The model consists of a segment model for two skis and a single body for the skier. It was implemented in the multibody simulation software LMS Virtual.Lab. The interaction of ski and snow leads to a normal and a shearing force. For the normal force a hypoplastic relation between force and penetration depth was used. Hypoplasticity considers the effect that compacted snow is inelastic and deformations remain. For the shearing force orthogonal metal cutting theory was applied. During turns the skier has to keep balance. He leans inward to compensate centrifugal force. Neglecting angulation the complement of the inward lean angle is the mean value of the edge angles of the left and the right ski. With a suitable choice of the edge angles the skier kept the balance. Using this model the trajectory of the skier was simulated over four and a half turns. The first turn was rather carved, but in the last turn strong skidding was present. Due to increasing speed the centrifugal force considerably exceeded the shearing strength of snow. The hypoplastic force-penetration relation led to a reasonable penetration depth, which is a crucial factor for the shearing force. Based on this reference simulation the influence of edge angle and forward/backward lean was assessed by performing parameter studies. An increased edge angle caused smaller turn radii. Surprisingly, forward lean caused larger and backward lean smaller turn radii. This phenomenon could be explained by the turn moment of the skier. Both effects were more dominant when the skis skidded.
Kinetics and Reaction Products of Ozone and Surface-Bound Squalene
Authors: Wells J. R. , Morrison Glenn C. , Coleman Beverly K.
Published: October 2008

Because of the high occupant density in aircraft, the surface chemistry of ozone and squalene, an important component of skin oil, was evaluated. A reaction probability of (45±14)×10−5 was determined for the reaction of squalene (2,6,10,15,19,23-hexamethyl-2,6,10,14,18,22-tetracosahexaene) with ozone (50 parts per billion (ppb)) on a glass plate surface using the Field and Laboratory Emission Cell (FLEC) Automation and Control System (FACS). To more clearly define part of squalene’s indoor environment degradation mechanism, gas-phase and surface-bound products of the squalene+O3 reaction were also investigated. Emitted products were captured in solution, derivatized with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA), and analyzed by gas chromatography and ion trap mass spectroscopy. The identified squalene+O3 reaction products were: 6-methyl-5-hepten-2-one (6MHO, ((CH3)2CCH(CH2)2 C(O)CH3)), glyoxal (ethanedial, HC(O)C(O)H), 4-oxopentanal (4OPA, CH3C(O)CH2CH2 CH(O)), and 6,10-dimethylundeca-5,9-dien-2-one (geranyl acetone). The compound 5,9,13-trimethyltetradeca-4,8,12-trienal is proposed as the other major squalene+O3 reaction product. This compound was determined from mass spectrometry coupled with plausible squalene+O3 reaction mechanisms based on previously published volatile organic compound+O3 gas-phase reaction mechanisms.
The importance of learning from past experience
Authors: Asher Kletz Trevor
Published: October 2008

While technology may change, people do not—they often make the same errors as earlier generations. Unfortunately, people forget the lessons of the past and allow the same failures to happen again. Furthermore, large organisations of people have no memory whatsoever. This paper describes some examples of recurring failures in the process industry, most of which have resulted in accidents and most of which could have been prevented if people were more aware of past experience. Suggestions for improving the documentation and dissemination of past failures are given.
Learning from collapse of piles in liquefiable soils
Authors: Bhattacharya Subhamoy , Blakeborough Anthony , Dash Suresh
Published: October 2008

Piled structures continue to fail during earthquakes despite being designed with the required safety factor against bending due to lateral loads. This paper suggests that the reason for this may be that when the ground liquefies, its reduction in lateral support allows piles to buckle under their axial load. The mechanism could have led to the collapse of many pile-supported structures in earthquakes worldwide and is likely to cause more damage in the future. The paper concludes that the practical implications could be far-reaching, requiring reassessment of existing structures in liquefiable soils as well as rewriting seismic design codes to take better account of the effects of axial load.
Pre-collision evolution of the Piñón oceanic terrane of SW Ecuador: stratigraphy and geochemistry of the “Calentura Formation”
Authors: Van Melle Jeremie , Vilema Washinton , Faure-Brac Bastien , Ordoñez Martha , Lapierre Henriette , Jimenez Nelson , Jaillard Etienne , Garcia Milton
Published: October 2008

The stratigraphic revision of the southern coastal Ecuadorian series makes possible the reconstruction of the pre-collision history of the Caribbean plateau accreted to the Ecuadorian margin. The Coniacian age of the oceanic basement (Piñón Fm) indicates that the latter is part of the Caribbean oceanic plateau. It is overlain by the Calentura Fm, which comprises from base to top: (i) 20 to 200 m of lavas and volcanic breccias of arc affinity (Las Orquídeas Mb), (ii) siliceous, organic rich black limestones of (middle?) Coniacian age, (iii) red, radiolarian rich, calcareous cherts ascribed to the Santonian-early Campanian, and (iv) marls, greywackes and island arc tuffs of Mid Campanian age. The latter are overlain by volcaniclastic turbidites of Mid to Late Campanian age (Cayo Fm), coeval to the Campanian-Maastrichtian island arc series locate farther west (San Lorenzo Fm).

The Las Orquídeas magmatic unit is interpreted as resulting from the melting of the Caribbean plateau, rather than from an ephemeral subduction process. The transition from coniacian limestones to santonian red cherts would be related to the thermal subsidence of the Caribbean plateau. The uplift of the latter and the development of the San Lorenzo island arc in the Middle Campanian would be due to the collision of the Caribbean plateau with the Mexican margin. Early in the Late Maastrichtian, the collision of the Caribbean plateau with the Ecuadorian margin would have triggered the cessation of the San Lorenzo arc activity. In the Late Paleocene, the Caribbean plateau was split into two terranes: the western Piñón terrane, which collided with the eastern Guaranda terrane.