bluuebunny/crossref_metadata_2025 huggingface dataset:
The Chemical Synthesis of Relaxin and Related Peptides
Authors: Wade John D. , Lin Feng , Hossain M. Akhter , Shabanpoor Fazel , Zhang Suode , Tregear Geoffrey W.
Published: April 2009

Successful methods for the chemical assembly of insulin‐like peptides allow the detailed study of their structure and function relationships. However, the two‐chain, three‐disulfide bond structure of this family of peptides, which includes relaxin, has long represented a significant challenge with respect to their chemical synthesis. Early efforts involved the random combination of the two synthetic S‐reduced chains under oxidizing conditions to spontaneously form the three disulfide bonds. Such an approach, while generally effective for native sequences, is critically dependent upon the presence of intact secondary structures within the individual chains which guide the subsequent folding and oxidation pathway. This limitation prevents the use of this approach for the preparation of analogs in which these secondary elements are either absent or modified. Nowadays, the use of highly efficient solid‐phase peptide synthesis methodologies together with selective S‐thiol‐protecting groups allows the acquisition of individual chains that can be combined by effective sequential chemically directed formation of each of the three disulfide bonds. These approaches have allowed the high‐yield assembly of an array of insulin‐like peptides which, in turn, has provided considerable and valuable structural and biological information.
Verification of a Relaxin‐3 Knockout/LacZ Reporter Mouse as a Model of Relaxin‐3 Deficiency
Authors: Smith Craig M. , Shen Pei‐Juan , Ma Sherie , Sutton Steve W. , Gundlach Andrew L.
Published: April 2009

Research on the neuropeptide relaxin‐3 has predominately been conducted in rats. Anatomical studies have yielded important information on the distribution of relaxin‐3 and its cognate receptor (RXFP3) within the brain, while functional studies have implicated relaxin‐3 as a modulator of feeding and stress responses. Therefore, the relaxin‐3/RXFP3 system represents a potential target for novel drugs to treat human disorders such as obesity, anxiety, and depression, but more research into this interesting neuropeptide in different experimental species is still required. Before conducting detailed neurochemical and behavioral examinations of a recently generated relaxin‐3 knockout mouse strain, the present study determined whether this mouse was a viable model of relaxin‐3 deficiency.
Evaluation of Relaxin's Antifibrotic Action by SELDI‐TOF Mass Spectrometry‐Based Profiling of Relaxin Knockout Mice, a Model of Progressive Fibrosis
Authors: Giannakis Eleni , Macris Mary , Chan Linda , Tregear Geoffrey W. , Samuel Chrishan S. , Wade John D.
Published: April 2009

Surface‐enhanced laser desorption ionization–time‐of‐flight mass spectrometry was employed to identify potential biomarkers for early‐onset fibrosis. These biomarkers were then used to evaluate the efficacy of relaxin to reverse or ameliorate the development of the condition.
Mortality burden of the 1918–1919 influenza pandemic in Europe
Authors: Ansart Séverine , Pelat Camille , Boelle Pierre‐Yves , Carrat Fabrice , Flahault Antoine , Valleron Alain‐Jacques
Published: April 2009

Background  The origin and estimated death toll of the 1918–1919 epidemic are still debated. Europe, one of the candidate sites for pandemic emergence, has detailed pandemic mortality information.

Objective  To determine the mortality impact of the 1918 pandemic in 14 European countries, accounting for approximately three‐quarters of the European population (250 million in 1918).

Methods  We analyzed monthly all‐cause civilian mortality rates in the 14 countries, accounting for approximately three‐quarters of the European population (250 million in 1918). A periodic regression model was applied to estimate excess mortality from 1906 to 1922. Using the 1906–1917 data as a training set, the method provided a non‐epidemic baseline for 1918–1922. Excess mortality was the mortality observed above this baseline. It represents the upper bound of the mortality attributable to the flu pandemic.

Results  Our analysis suggests that 2·64 million excess deaths occurred in Europe during the period when Spanish flu was circulating. The method provided space variation of the excess mortality: the highest and lowest cumulative excess/predicted mortality ratios were observed in Italy (+172%) and Finland (+33%). Excess‐death curves showed high synchrony in 1918–1919 with peak mortality occurring in all countries during a 2‐month window (Oct–Nov 1918).

Conclusions  During the Spanish flu, the excess mortality was 1·1% of the European population. Our study highlights the synchrony of the mortality waves in the different countries, which pleads against a European origin of the pandemic, as was sometimes hypothesized.
Galectins and Gliomas
Authors: Le Mercier Marie , Fortin Shannon , Mathieu Véronique , Kiss Robert , Lefranc Florence
Published: April 2009

Malignant gliomas, especially glioblastomas, are associated with a dismal prognosis. Despite advances in diagnosis and treatment, glioblastoma patients still have a median survival expectancy of only 14 months. This poor prognosis can be at least partly explained by the fact that glioma cells diffusely infiltrate the brain parenchyma and exhibit decreased levels of apoptosis, and thus resistance to cytotoxic drugs. Galectins are a family of mammalian beta‐galactoside‐binding proteins characterized by a shared characteristic amino acid sequence. They are expressed differentially in normal vs. neoplastic tissues and are known to play important roles in several biological processes such as cell proliferation, death and migration. This review focuses on the role played by galectins, especially galectin‐1 and galectin‐3, in glioma biology. The involvement of these galectins in different steps of glioma malignant progression such as migration, angiogenesis or chemoresistance makes them potentially good targets for the development of new drugs to combat these malignant tumors.
Hydrologic and Water Quality Functions of a Disturbed Wetland in an Agricultural Setting1
Authors: Rogers Justin S. , Potter Kenneth W. , Hoffman Adam R. , Hoopes John A. , Wu Chin H. , Armstrong David E.
Published: April 2009

Abstract: In 2006, we collected flow, sediment, and phosphorus (P) data at stream locations upstream and downstream of a small degraded wetland in south‐central Wisconsin traversed by a stream draining a predominantly agricultural watershed. The amount of sediment that left the wetland in the two largest storms, which accounted for 96% of the exported sediment during the observation period, was twice the amount that entered the wetland, even though only 50% of the wetland had been inundated. This apparently anomalous result is due to erosion of sediment that had accumulated in the low‐gradient channel and to the role of drainage ditches, which trapped sediment during the wetland‐filling phase. In the case of total P, the inflow to the wetland approximately equaled the outflow, although the wetland sequestered 30% of the incoming dissolved reactive P. The discrepancy is almost certainly due to net export of sediment. Many wetlands in the glaciated midwestern United States are ditched and traversed by low‐gradient channels draining predominantly agricultural areas, so the processes observed in this wetland are likely to be common in that region. Knowledge of this behavior presents opportunities to improve water quality in this and similar regions.
Sensitivity and Uncertainty of Ground‐Water Discharge Estimates for Semiarid Shrublands1
Authors: Zhu Jianting , Young Michael H.
Published: April 2009

Abstract:  We proposed a step‐by‐step approach to quantify the sensitivity of ground‐water discharge by evapotranspiration (ET) to three categories of independent input variables. To illustrate the approach, we adopt a basic ground‐water discharge estimation model, in which the volume of ground water lost to ET was computed as the product of the ground‐water discharge rate and the associated area. The ground‐water discharge rate was assumed to equal the ET rate minus local precipitation. The objective of this study is to outline a step‐by‐step procedure to quantify the contributions from individual independent variable uncertainties to the uncertainty of total ground‐water discharge estimates; the independent variables include ET rates of individual ET units, areas associated with the ET units, and precipitation in each subbasin. The specific goal is to guide future characterization efforts by better targeting data collection for those variables most responsible for uncertainty in ground‐water discharge estimates. The influential independent variables to be included in the sensitivity analysis are first selected based on the physical characteristics and model structure. Both regression coefficients and standardized regression coefficients for the selected independent variables are calculated using the results from sampling‐based Monte Carlo simulations. Results illustrate that, while as many as 630 independent variables potentially contribute to the calculation of the total annual ground‐water discharge for the case study area, a selection of seven independent variables could be used to develop an accurate regression model, accounting for more than 96% of the total variance in ground‐water discharge. Results indicate that the variability of ET rate for moderately dense desert shrubland contributes to about 75% of the variance in the total ground‐water discharge estimates. These results point to a need to better quantify ET rates for moderately dense shrubland to reduce overall uncertainty in estimates of ground‐water discharge. While the approach proposed here uses a basic ground‐water discharge model taken from an earlier study, the procedure of quantifying uncertainty and sensitivity can be generalized to handle other types of environmental models involving large numbers of independent variables.
Impact of an Invasive Exotic Species on Stream Nitrogen Levels in Southern Illinois1
Authors: Goldstein Christine L. , Williard Karl W.J. , Schoonover Jon E.
Published: April 2009

Abstract: Autumn‐olive (Elaeagnus umbellataThunb.) is an invasive, exotic shrub that has become naturalized in the eastern United States. Autumn‐olive fixes nitrogen (N) via a symbiotic relationship with the actinomyceteFrankia. At the plot scale, the presence of autumn‐olive has been related to elevated soil water nitrate‐N (NO3−‐N) concentrations. This study examined the relationship between autumn‐olive cover in a watershed and stream water quality. Stream water nitrate‐N (NO3−‐N) and ammonium‐N (NH4+‐N) concentrations were measured in 12 first order ephemeral streams draining watersheds with mixed forest cover and a range of 0‐35% autumn‐olive cover. Percent autumn‐olive cover was positively correlated with mean stream NO3−‐N concentrations, but was not correlated with mean stream NH4+‐N concentrations. While other studies have demonstrated a significant relationship between native N‐fixers and stream NO3−‐N, this is the first study to document a relationship for an invasive, exotic N‐fixing species. Results suggest that this exotic species can be an additional source of NO3−in local and regional water bodies and demonstrates an additional negative ecosystem consequence of invasion beyond losses in biodiversity.
Effect of the Spatial Variability of Land Use, Soil Type, and Precipitation on Streamflows in Small Watersheds1
Authors: Cho Huidae , Olivera Francisco
Published: April 2009

Abstract:  The spatial variability of the data used in models includes the spatial discretization of the system into subsystems, the data resolution, and the spatial distribution of hydrologic features and parameters. In this study, we investigate the effect of the spatial distribution of land use, soil type, and precipitation on the simulated flows at the outlet of “small watersheds” (i.e., watersheds with times of concentration shorter than the model computational time step). The Soil and Water Assessment Tool model was used to estimate runoff and hydrographs. Different representations of the spatial data resulted in comparable model performances and even the use of uniform land use and soil type maps, instead of spatially distributed, was not noticeable. It was found that, although spatially distributed data help understand the characteristics of the watershed and provide valuable information to distributed hydrologic models, when the watershed is small, realistic representations of the spatial data do not necessarily improve the model performance. The results obtained from this study provide insights on the relevance of taking into account the spatial distribution of land use, soil type, and precipitation when modeling small watersheds.
Modeling Postfire Response and Recovery using the Hydrologic Engineering Center Hydrologic Modeling System (HEC‐HMS)1
Authors: Cydzik Kristina , Hogue Terri S.
Published: April 2009

Abstract:  This paper investigates application of the Army Corps of Engineers’ Hydrologic Engineering Center Hydrologic Modeling System (HEC‐HMS) to a burned watershed in San Bernardino County, California. We evaluate the HEC‐HMS’ ability to simulate discharge in prefire and postfire conditions in a semi arid watershed and the necessary parameterizations for modeling hydrologic response during the immediate, and subsequent recovery, period after a wildfire. The model is applied to City Creek watershed, which was 90% burned during the Old Fire of October 2003. An optimal spatial resolution for the HEC‐HMS model was chosen based on an initial sensitivity analysis of subbasin configurations and related model performance. Five prefire storms were calibrated for the selected model resolution, defining a set of parameters that reasonably simulate prefire conditions. Six postfire storms, two from each of the following rainy (winter) seasons were then selected to simulate postfire response and evaluate relative changes in parameter values and model behavior. There were clear trends in the postfire parameters [initial abstractions (Ia), curve number (CN), and lag time] that reveal significant (and expected) changes in watershed behavior. CN returns to prefire (baseline) values by the end of Year 2, while Ia approaches baseline by the end of the third rainy season. However, lag time remains significantly lower than prefire values throughout the three‐year study period. Our results indicate that recovery of soil conditions and related runoff response is not entirely evidenced by the end of the study period (three rainy seasons postfire). Understanding the evolution of the land surface and related hydrologic properties during the highly dynamic postfire period, and accounting for these changes in model parameterizations, will allow for more accurate and reliable discharge simulations in both the immediate, and subsequent, rainy seasons following fire.
Flood risk management and planning policy in a time of policy transition: the case of the Wapshott Road Planning Inquiry, Surrey, England
Authors: Tunstall S. , McCarthy S. , Faulkner H.
Published: April 2009

This paper focuses on an English case study example of decision making on development and flood risk. It was carried out through qualitative document analysis and 13 in‐depth interviews with flood risk professionals and others in the Lower Thames Valley. It illustrates the recent shift in policy in England from flood defence to a flood risk management approach with an increased emphasis on spatial planning and development control. It shows that decision makers take time to come to terms with new government policy. Despite the more prescriptive government guidance on development and flood risk in Planning Policy Guidance 25 and later documents, there remains scope for disagreements, for example, over what constitutes ‘safe’ development in flood risk areas. Other sustainability objectives can still weigh heavily against flood risk in local decision making. The potential contributions of modelling, and new visualisation techniques in the flood risk management and planning context are considered.
tossm: an R package for assessing performance of genetic analytical methods in a management context
Authors: MARTIEN KAREN K. , GREGOVICH DAVE , BRAVINGTON MARK V. , PUNT ANDRÉ E. , STRAND ALLAN E. , TALLMON DAVID A. , TAYLOR BARBARA L.
Published: April 2009

tossm (Testing of Spatial Structure Methods) is a package for testing the performance of genetic analytical methods in a management context. In the tossm package, any method developed to detect population genetic structure can be combined with a mechanism for creating management units (MUs) based on the genetic analysis. The resulting Boundary‐Setting Algorithm (BSA) dictates harvest boundaries with a genetic basis. These BSAs can be evaluated with respect to how well the MUs they define meet management objectives.
Id2 suppression of p15 counters TGF‐β‐mediated growth inhibition of melanoma cells
Authors: Schlegel Natalie C. , Eichhoff Ossia M. , Hemmi Silvio , Werner Sabine , Dummer Reinhard , Hoek Keith S.
Published: April 2009

Proliferative resistance to transforming growth factor β (TGF‐β) is regarded as a critical turning point in the malignant progression of many cancer types. In melanoma this resistance is associated with more aggressive metastatic behaviour. A recent study by our group identified proliferative and invasive subtypes of melanoma cultures and found that these are, respectively, susceptible and resistant to TGF‐β suppression of proliferation. Here, using previously characterised proliferative and invasive phenotype melanoma cultures, we explored molecular responses involved in modulating susceptibility to TGF‐β‐mediated inhibition of proliferation. The Id2 gene was identified as being expressed more strongly in invasive phenotype cells less susceptible to TGF‐β repression than in proliferative phenotype cells. We correlated TGF‐β repression of Id2 gene expression in proliferative phenotype cells with p15Ink4b induction and cell cycle arrest. Furthermore, ectopic Id2 expression in proliferative phenotype cells counteracted p15Ink4b induction and consequently protected them from TGF‐β‐mediated inhibition of proliferation. We conclude that transition to increased aggressiveness in melanoma cells requires Id2 upregulation to suppress TGF‐β induction of p15Ink4b and thus help to circumvent TGF‐β‐mediated inhibition of proliferation.
Mock Jacobi forms in basic hypergeometric series
Authors: Kang Soon-Yi
Published: April 2009

We show that someq-series such as universal mock theta functions are linear sums of theta quotients and mock Jacobi forms of weight 1/2, which become holomorphic parts of real analytic modular forms when they are restricted to torsion points and multiplied by suitable powers ofq. We also prove that certain linear sums ofq-series are weakly holomorphic modular forms of weight 1/2 due to annihilation of mock Jacobi forms or completion by mock Jacobi forms. As an application, we obtain a relation between the rank and crank of a partition.
Neurotensin inhibition of GABAergic transmission via mGluR‐induced endocannabinoid signalling in rat periaqueductal grey
Authors: Mitchell V. A. , Kawahara H. , Vaughan C. W.
Published: April 2009

Neurotensin modulates pain via its actions within descending analgesic pathways which include brain regions such as the midbrain periaqueductal grey (PAG). The aim of this study was to examine the cellular actions of neurotensin on PAG neurons. Whole cell patch clamp recordings were made from rat midbrain PAG slicesin vitroto examine the postsynaptic effects of neurotensin and its effects on GABAAmediated inhibitory postsynaptic currents (IPSCs). Neurotensin (100–300 nm) produced an inward current in subpopulations of opioid sensitive and insensitive PAG neurons which did not reverse over membrane potentials between –50 and –130 mV. The neurotensin induced current was abolished by the NTS1 and NTS1/2 antagonists SR48692 (300 nm) and SR142948A (300 nm). Neurotensin also produced a reduction in the amplitude of evoked IPSCs, but had no effect on the rate and amplitude of TTX‐resistant miniature IPSCs. The neurotensin induced inhibition of evoked IPSCs was reduced by the mGluR5 antagonist MPEP (5μm) and abolished by the cannabinoid CB1receptor antagonist AM251 (3μm). These results suggest that neurotensin produces direct neuronal depolarisation via NTS1 receptors and inhibits GABAergic synaptic transmission within the PAG. The inhibition of synaptic transmission is mediated by neuronal excitation and action potential dependent release of glutamate, leading to mGluR5 mediated production of endocannabinoids which activate presynaptic CB1receptors. Thus, neurotensin has cellular actions within the PAG which are consistent with both algesic and analgesic activity, some of which are mediated via the endocannabinoid system.
Dynamic pressure–flow relationship of the cerebral circulation during acute increase in arterial pressure
Authors: Zhang Rong , Behbehani Khosrow , Levine Benjamin D.
Published: April 2009

The physiological mechanism(s) for the regulation of the dynamic pressure–flow relationship of the cerebral circulation are not well understood. We studied the effects of acute cerebral vasoconstriction on the transfer function between spontaneous changes in blood pressure (BP) and cerebral blood flow velocity (CBFV) in 13 healthy subjects (30 ± 7 years). CBFV was measured in the middle cerebral artery using transcranial Doppler. BP was increased stepwise with phenylephrine infusion at 0.5, 1.0 and 2.0 μg kg–1 min–1. Phenylephrine increased BP by 11, 23 and 37% from baseline, while CBFV increased (11%) only with the highest increase in BP. Cerebrovascular resistance index (BP/CBFV) increased progressively by 6, 17 and 23%, demonstrating effective steady‐state autoregulation. Transfer function gain at the low frequencies (LF, 0.07–0.20 Hz) was reduced by 15, 14 and 14%, while the phase was reduced by 10, 17 and 31%. A similar trend of changes was observed at the high frequencies (HF, 0.20–0.35 Hz), but gain and phase remained unchanged at the very low frequencies (VLF, 0.02–0.07 Hz). Windkessel model simulation suggests that increases in steady‐state cerebrovascular resistance and/or decreases in vascular compliance during cerebral vasoconstriction contribute to the changes in gain and phase. These findings suggest that changes in steady‐state cerebrovascular resistance and/or vascular compliance modulate the dynamic pressure–flow relationship at the low and high frequencies, while dynamic autoregulation is likely to be dominant at the very low frequencies. Thus, oscillations in CBFV are modulated not only by dynamic autoregulation, but also by changes in steady‐state cerebrovascular resistance and/or vascular compliance.
Heterogeneity in function of small artery smooth muscle BKCa: involvement of the β1‐subunit
Authors: Yang Yan , Murphy Timothy V. , Ella Srikanth R. , Grayson T. Hilton , Haddock Rebecca , Hwang Yun T. , Braun Andrew P. , Peichun Gui , Korthuis Ronald J. , Davis Michael J. , Hill Michael A.
Published: April 2009

Arteriolar myogenic vasoconstriction occurs when increased stretch or membrane tension leads to smooth muscle cell depolarization and opening of voltage‐gated Ca2+channels. To prevent positive feedback and excessive pressure‐induced vasoconstriction, studies in cerebral artery smooth muscle have suggested that activation of large conductance, Ca2+‐activated K+channels (BKCa) provides an opposing hyperpolarizing influence reducing Ca2+channel activity. We have hypothesized that this mechanism may not equally apply to all vascular beds. To establish the existence of such heterogeneity in vascular reactivity, studies were performed on rat vascular smooth muscle (VSM) cells from cremaster muscle arterioles and cerebral arteries. Whole cell K+currents were determined at pipette [Ca2+] of 100 nmor 5 μmin the presence and absence of the BKCainhibitor, iberiotoxin (IBTX; 0.1 μm). Similar outward current densities were observed for the two cell preparations at the lower pipette Ca2+levels. At 5 μmCa2+, cremaster VSM showed a significantly (P< 0.05) lower current density compared to cerebral VSM (34.5 ± 1.9 vs 45.5 ± 1.7 pA pF−1at +70 mV). Studies with IBTX suggested that the differences in K+conductance at 5 μmintracellular [Ca2+] were largely due to activity of BKCa. 17β‐Oestradiol (1 μm), reported to potentiate BKCacurrent via the channel's β‐subunit, caused a greater effect on whole cell K+currents in cerebral vessel smooth muscle cells (SMCs) compared to those of cremaster muscle. In contrast, the α‐subunit‐selective BKCaopener, NS‐1619 (20 μm), exerted a similar effect in both preparations. Spontaneously transient outward currents (STOCs) were more apparent (frequency and amplitude) and occurred at more negative membrane potentials in cerebral compared to cremaster SMCs. Also consistent with decreased STOC activity in cremaster SMCs was an absence of detectable Ca2+sparks (0 of 76 cells) compared to that in cerebral SMCs (76 of 105 cells). Quantitative PCR showed decreased mRNA expression for the β1 subunit and a decrease in the β 1: α ratio in cremaster arterioles compared to cerebral vessels. Similarly, cremaster arterioles showed a decrease in total BKCaprotein and the β 1: α‐subunit ratio. The data support vascular heterogeneity with respect to the activity of BKCain terms of both β‐subunit regulation and interaction with SR‐mediated Ca2+signalling.
The role of intrinsic muscle mechanics in the neuromuscular control of stable running in the guinea fowl
Authors: Daley Monica A. , Voloshina Alexandra , Biewener Andrew A.
Published: April 2009

Here we investigate the interplay between intrinsic mechanical and neural factors in muscle contractile performance during running, which has been less studied than during walking. We report in vivo recordings of the gastrocnemius muscle of the guinea fowl (Numida meleagris), during the response and recovery from an unexpected drop in terrain. Previous studies on leg and joint mechanics following this perturbation suggested that distal leg extensor muscles play a key role in stabilisation. Here, we test this through direct recordings of gastrocnemius fascicle length (using sonomicrometry), muscle–tendon force (using buckle transducers), and activity (using indwelling EMG). Muscle recordings were analysed from the stride just before to the second stride following the perturbation. The gastrocnemius exhibits altered force and work output in the perturbed and first recovery strides. Muscle work correlates strongly with leg posture at the time of ground contact. When the leg is more extended in the drop step, net gastrocnemius work decreases (−5.2 J kg−1versus control), and when the leg is more flexed in the step back up, it increases (+9.8 J kg−1versus control). The muscle's work output is inherently stabilising because it pushes the body back toward its pre‐perturbation (level running) speed and leg posture. Gastrocnemius length and force return to level running means by the second stride following the perturbation. EMG intensity differs significantly from level running only in the first recovery stride following the perturbation, not within the perturbed stride. The findings suggest that intrinsic mechanical factors contribute substantially to the initial changes in muscle force and work. The statistical results suggest that a history‐dependent effect, shortening deactivation, may be an important factor in the intrinsic mechanical changes, in addition to instantaneous force–velocity and force–length effects. This finding suggests the potential need to incorporate history‐dependent muscle properties into neuromechanical simulations of running, particularly if high muscle strains are involved and stability characteristics are important. Future work should test whether a Hill or modified Hill type model provides adequate prediction in such conditions. Interpreted in light of previous studies on walking, the findings support the concept of speed‐dependent roles of reflex feedback.
The Effect of Adding Roughness and Thickness to a Transonic Axial Compressor Rotor
Authors: Suder K. L. , Chima R. V. , Strazisar A. J. , Roberts W. B.
Published: April 2009

The performance deterioration of a high-speed axial compressor rotor due to surface roughness and airfoil thickness variations is reported. A 0.025 mm (0.001 in.) thick rough coating with a surface finish of 2.54–3.18 rms μm (100–125 rms μin.) is applied to the pressure and suction surface of the rotor blades. Coating both surfaces increases the leading edge thickness by 10 percent at the hub and 20 percent at the tip. Application of this coating results in a loss in efficiency of 6 points and a 9 percent reduction in the pressure ratio across the rotor at an operating condition near the design point. To separate the effects of thickness and roughness, a smooth coating of equal thickness is also applied to the blade. The smooth coating surface finish is 0.254–0.508 rms μm (10–20 rms μin.), compared to the bare metal blade surface finish of 0.508 rms pm (20 rms μin.). The smooth coating results in approximately half of the performance deterioration found from the rough coating. Both coatings are then applied to different portions of the blade surface to determine which portions of the airfoil are most sensitive to thickness/roughness variations. Aerodynamic performance measurements are presented for a number of coating configurations at 60, 80, and 100 percent of design speed. The results indicate that thickness/roughness over the first 2 percent of blade chord accounts for virtually all of the observed performance degradation for the smooth coating, compared to about 70 percent of the observed performance degradation for the rough coating. The performance deterioration is investigated in more detail at design speed using laser anemometer measurements as well as predictions generated by a quasi-three-dimensional Navier–Stokes flow solver, which includes a surface roughness model. Measurements and analysis are performed on the baseline blade and the full-coverage smooth and rough coatings. The results indicate that adding roughness at the blade leading edge causes a thickening of the blade boundary layers. The interaction between the rotor passage shock and the thickened suction surface boundary layer then results in an increase in blockage, which reduces the diffusion level in the rear half of the blade passage, thus reducing the aerodynamic performance of the rotor.
Unsteady Three-Dimensional Flow in a Single-Stage Transonic Fan: Part II—Unsteady Stator Exit Flow Field
Authors: Cherrett M. A. , Bryce J. D. , Ginder R. B.
Published: April 2009

Detailed unsteady aerodynamic measurements have been taken in a single-stage transonic fan with a very high stage-hub loading. Two-dimensional dynamic yawmeter probes, capable of measuring mean levels and fluctuations in stagnation pressure, static pressure, and yaw angle have been traversed at rotor exit and downstream of the stator, along with several types of pneumatic three-dimensional probe. Part I describes measurements taken at rotor exit. This paper, Part II, describes measurements taken at stator exit when the fan was operating at near-peak efficiency, on the design speed characteristic. The measurements indicate the effects of Rotor-Stator interaction on the development of the viscous endwall-corner flows at the hub and casing. In addition, they illustrate that significant changes in stagnation pressure level occur within much of the stator exit flow field during the rotor passing cycle.
A New Endwall Model for Axial Compressor Throughflow Calculations
Authors: Dunham J.
Published: April 2009

It is well recognized that the endwall regions of a compressor—in which the annulus wall flow interacts with the mainstream flow—have a major influence on its efficiency and surge margin. Despite many attempts over the years to predict the very complex flow patterns in the endwall regions, current compressor design methods still rely largely on empirical estimates of the aerodynamic losses and flow angle deviations in these regions. This paper describes a new phenomenological model of the key endwall flow phenomena treated in a circumferentially averaged way. It starts from Hirsch and de Ruyck’s annulus wall boundary layer approach, but makes some important changes. The secondary vorticities arising from passage secondary flows and from tip clearance flows are calculated. Then the radial interchanges of momentum, energy, and entropy arising from both diffusion and convection are estimated. The model is incorporated into a streamline curvature program. The empirical blade force defect terms in the boundary layers are selected from cascade data. The effectiveness of the method is illustrated by comparing the predictions with experimental results on both low-speed and high-speed multistage compressors. It is found that the radial variation of flow parameters is quite well predicted, and so is the overall performance, except when significant endwall stall occurs.
Endwall and Unsteady Flow Phenomena in an Axial Turbine Stage
Authors: Gallus H. E. , Zeschky J. , Hah C.
Published: April 2009

Detailed experimental and numerical studies have been performed in a subsonic, axial-flow turbine stage to investigate the secondary flow field, the aerodynamic loss generation, and the spanwise mixing under a stage environment. The experimental study includes measurements of the static pressure distribution on the rotor blade surface and the rotor exit flow field using three-dimensional hot-wire and pneumatic probes. The rotor exit flow field was measured with an unsteady hot-wire probe, which has high temporal and spatial resolution. Both steady and unsteady numerical analyses were performed with a three-dimensional Navier–Stokes code for the multiple blade rows. Special attention was focused on how well the steady multiple-blade-row calculation predicts the rotor exit flow field and how much the blade interaction affects the radial distribution of flow properties at the stage exit. Detailed comparisons between the measurement and the steady calculation indicate that the steady multiple-blade-row calculation predicts the overall time-averaged flow field very well. However, the steady calculation does not predict the secondary flow at the stage exit accurately. The current study indicates that the passage vortex near the hub of the rotor is transported toward the midspan due to the blade interaction effects. Also, the structure of the secondary flow field at the exit of the rotor is significantly modified by the unsteady effects. The time-averaged secondary flow field and the radial distribution of the flow properties, which are used for the design of the following stage, can be predicted more accurately with the unsteady flow calculation.
Off-Design Flow Measurements in a Centrifugal Compressor Vaneless Diffuser
Authors: Pinarbasi A. , Johnson M. W.
Published: April 2009

Detailed measurements have been taken of the three-dimensional velocity field within the vaneless diffuser of a backswept low speed centrifugal compressor using hot-wire anemometry. A 16 percent below and an 11 percent above design flow rate were used in the present study. Results at both flow rates show how the blade wake mixes out more rapidly than the passage wake. Strong secondary flows inherited from the impeller at the higher flow rate delay the mixing out of the circumferential velocity variations, but at both flow rates these circumferential variations are negligible at the last measurement station. The measured tangential/radial flow angle is used to recommend optimum values for the vaneless space and vane angle for design of a vaned diffuser.
On Fast-Response Probes: Part 2—Aerodynamic Probe Design Studies
Authors: Humm H. J. , Gossweiler C. R. , Gyarmathy G.
Published: April 2009

The influence of the probe size and geometry on the quality of fast-response measurements in turbomachines has been experimentally investigated. For investigations in the static domain (time-independent flows) probes were calibrated in two continuously operating wind tunnels in the range 0.2 < M < 1.2. For dynamic calibrations in time-variant flows model experiments in water (0.025 < k < 0.4, reduced frequency) were performed. Aerodynamic characteristics were determined for a great number of probe geometries, such as circular cylinders and wedge-type probes with varied apex angles, locations of the sensing holes, and leading edge shapes. The experiments comprised investigations in tolerance ranges for prismatic total pressure probes, yaw angle sensitivity, yaw angle, and Mach number effects on calibration and influence of dynamic yaw angle fluctuation on probe characteristics. As a result of the experiments errors due to static and dynamic aerodynamic effects could be quantified. The majority of the errors arising during measurements in turbomachines can be directly related to the probe size. An important number of these errors are systematic and can be analytically modeled and hence their influence corrected. In fluctuating flows the most severe measurement errors, which often may exceed the quantity of interest, are due to dynamic stall effects. This phenomenon, which is of transient nature and cannot be corrected, is typical for sharp wedge probes, but is not present with circular cylinders, and the effects are much smaller with very blunt wedges.
The Development of Fast Response Aerodynamic Probes for Flow Measurements in Turbomachinery
Authors: Ainsworth R. W. , Allen J. L. , Batt J. J. M.
Published: April 2009

The advent of a new generation of transient rotating turbine simulation facilities, where engine values of Reynolds and Mach number are matched simultaneously together with the relevant rotational parameters for dimensional similitude (Dunn et al., 1988; Epstein and Guenette, 1984; Ainsworth et al., 1988), has provided the stimulus for developing improved instrumentation for investigating the aerodynamic flows in these stages. Much useful work has been conducted in the past using hot-wire and laser anemometers. However, hot-wire anemometers are prone to breakage in the high-pressure flows required for correct Reynolds numbers. Furthermore, some laser techniques require a longer run-time than these transient facilities permit, and generally yield velocity information only, giving no data on loss production. Advances in semiconductor aerodynamic probes are beginning to fulfill this perceived need. This paper describes advances made in the design, construction, and testing of two and three-dimensional fast response aerodynamic probes, where semiconductor pressure sensors are mounted directly on the surface of the probes, using techniques that have previously been successfully used on the surface of rotor blades (Ainsworth et al., 1991). These are to be used to measure Mach number and flow direction in compressible unsteady flow regimes. In the first section, a brief review is made of the sensor and associated technology that has been developed to permit a flexible design of fast response aerodynamic probe. Following this, an extensive program of testing large-scale aerodynamic models of candidate geometries for suitable semiconductor scale probes is described, and the results of these discussed. The conclusions of these experiments, conducted for turbine representative mean and unsteady flows, yielded new information for optimizing the design of the small-scale semiconductor probes, in terms of probe geometry, sensor placement, and aerodynamic performance. Details are given of a range of wedge and pyramid semiconductor probes constructed, and the procedures used in calibrating and making measurements with them. Differences in performance are discussed, allowing the experimenter to choose an appropriate probe for the particular measurement required. Finally, the application of prototype semiconductor probes in a transient rotor experiment at HP turbine representative conditions is described, and the data so obtained are compared with CFD solutions of the unsteady viscous flow-field.
Darryl E. Metzger Memorial Session Paper: Surface Heat Transfer From a Three-Pass Blade Cooling Passage Simulator
Authors: Chyu M. K. , Natarajan V.
Published: April 2009

Using an analogous mass transfer system based on naphthalene sublimation, the present research focuses on investigating the local heat transfer characteristics from three-pass smooth and turbulated blade cooling passages. To simulate the actual passage geometry, the test model is incorporated with trapezoidal cross sections including variable passage sizes. Measured local mass transfer results reveal strong evidence of velocity redistribution over the trapezoidal flow area. Elevated mass transfer always exists in the vicinity of a sharp turn. However, in the present study, one of the most notable mass transfer increases is perceived in the third pass, downstream to the second turn, where the flow area is reduced severely. Overall, the combined effects of the three-pass and two sharp turns virtually double the mass transfer as compared to its straight counterpart with fully developed, turbulent flow. With a pitch-to-height ratio equal to 10 and 90 deg orientation, the rib turbulators produce approximately an additional 30 percent of overall mass transfer enhancement in comparison to the smooth case. Locally, rib-induced enhancement varies with different surfaces and passes. The greatest enhancement lies on the first pass, about 40 percent; the other two passes are comparable, less than 20 percent.
Microplane Constitutive Model and Metal Plasticity
Authors: Brocca Michele , Bazˇant Zdeneˇk P.
Published: April 2009

The microplane model is a versatile constitutive model in which the stress-strain relations are defined in terms of vectors rather than tensors on planes of all possible orientations, called the microplanes, representative of the microstructure of the material. The microplane model with kinematic constraint has been successfully employed in the modeling of concrete, soils, ice, rocks, fiber composites and other quasibrittle materials. The microplane model provides a powerful and efficient numerical tool for the development and implementation of constitutive models for any kind of material. The paper presents a review of the background from which the microplane model stems, highlighting differences and similarities with other approaches. The basic structure of the microplane model is then presented, together with its extension to finite strain deformation. Three microplane models for metal plasticity are introduced and discussed. They are compared mutually and with the classical J2-flow theory for incremental plasticity by means of two examples. The first is the material response to a nonproportional loading path given by uniaxial compression into the plastic region followed by shear (typical of buckling and bifurcation problems). This example is considered in order to show the capability of the microplane model to represent a vertex on the yield surface. The second example is the ‘tube-squash’ test of a highly ductile steel tube: a finite element computation is run using two microplane models and the J2-flow theory. One of the microplane models appears to predict more accurately the final shape of the deformed tube, showing an improvement compared to the J2-flow theory even when the material is not subjected to abrupt changes in the loading path direction. This review article includes 114 references.
Nonholonomic Mechanics
Authors: Mei Fengxiang
Published: April 2009

This is a concise review of nonholonomic mechanics. It deals with the fundamental concepts, variational principles, equations of motion, special problems, integration methods, algebraic structure, and the geometrical methods of nonholonomic mechanics. It also points out some problems for future research. There are 90 references.
Survey of Stress Analyses of the Femoral Hip Prosthesis
Authors: Joshi Makarand G. , Santare Michael H. , Advani Suresh G.
Published: April 2009

The finite element method has been used to analyze hip prostheses for the past 25+ years and has proven to be quite effective. The use of finite element analysis, initially, was restricted to duplicating experimental results but has progressed over the decades in step with the computational capabilities as well as the increased understanding of hip replacement procedures. The mechanics of the bone-prosthesis system is quite complicated in the context of the geometry, material properties, loading and the interaction between the femur and the hip stem. The following article is a survey of the finite element technique as applied by researchers over the past three decades, within given limitations, to solve this complex problem. The discussion is limited to the analysis of the femoral component and consists of the approximations, methodologies and conclusions as reported. Relevant experimental results have also been reviewed. There are 136 references cited.
Fluid Flow and Heat Transfer at Micro- and Meso-Scales With Application to Heat Exchanger Design
Authors: Mehendale S. S. , Jacobi A. M. , Shah R. K.
Published: April 2009

By their very nature, compact heat exchangers allow an efficient use of material, volume, and energy in thermal systems. These benefits have driven heat exchanger design toward higher compactness, and the trend toward ultra-compact designs will continue. Highly compact surfaces can be manufactured using micro-machining and other modern technologies. In this paper, unresolved thermal-hydraulic issues related to ultra-compact designs are discussed, and the status of the technologies required for the production of ultra-compact structured surfaces is summarized. This review article includes 67 references.
A Survey of Heat Transfer in Separated and Reattached Flows
Authors: Ota Terukazu
Published: April 2009

Heat and mass transfer in the separated, reattached, and redeveloping regions of incompressible or compressible flow is very important in relation to many types of heat exchangers. There have been numerous works published describing these flows for a wide variety of geometric configurations, In the present article, a survey is made of published studies of heat transfer in the separated, reattached, and redeveloping regions of incompressible flow around or in a wide variety of flow configurations. Flow configurations cited in the article are the downward facing step, the sudden expansion plane channel, the abrupt expansion tube, the blunt flat plate, the longitudinal blunt circular cylinder, and the surface mounted obstacle. The laminar and turbulent flow cases using both experimental and numerical methodologies are reviewed. This review article includes 268 references.
Plastics Product and Process Design Strategies
Authors: Karania Ruchi , Kazmer David , Roser Christoph
Published: April 2009

Plastic components are vital components of many engineered products, frequently representing 20–40% of the product value. While injection molding is the most common process for economically producing complex designs in large quantities, a large initial monetary investment is required to develop appropriate tooling. Accordingly, injection molding may not be appropriate for applications that are not guaranteed to recoup the initial costs. In this paper, component cost and lead-time models are developed from industry data for an electrical enclosure consisting of two parts produced by a variety of low to medium volume manufacturing processes including fused deposition modeling, direct fabrication, and injection molding with used tooling, soft prototype tooling, and hard tooling. The viability of each process is compared with respect to the manufacturing cost and lead time for specific production quantities of one hundred, one thousand, and ten thousand. The results indicate that the average cost per enclosure assembly is highly sensitive to the production quantity, varying in range from $243 per enclosure for quantity one hundred to $0.52 per enclosure for quantity ten thousand. The most appropriate process varies greatly with the desired production quantity and cost/lead time sensitivity. As such, a probabilistic analysis was utilized to evaluate the effect of uncertain demand and market delays, the result of which demonstrated the importance of maintaining supply chain flexibility by minimizing initial cost and lead time.