bluuebunny/crossref_metadata_2025 huggingface dataset:
Bi‐Directional Calcium Signaling Between Adjacent Leukocytes and Trophoblast‐Like Cells
Authors: Elfline Megan , Clark Andrea , Petty Howard R. , Romero Roberto
Published: March 2010

Citation Elfline M, Clark A, Petty HR, Romero R. Bi‐directional calcium signaling between adjacent leukocytes and trophoblast‐like cells. Am J Reprod Immunol 2010

Problem  Trophoblasts are believed to play an important role in mitigating immunological responses against the fetus. To better understand the nature of trophoblast–leukocyte interactions, we have studied signal transduction during intercellular interactions.

Method of study  Using a highly sensitive microfluorometric ratioing method and Ca2+‐sensitive dyes, we measured Ca2+ signals in trophoblast‐like cell lines (JEG‐3 and JAR) or in leukocytes (neutrophils and monocytes) during intercellular contact.

Results  Trophoblast cell lines exhibit Ca2+ signals during leukocyte contact. In contrast, leukocytes cannot elicit Ca2+ signals in non‐opsonized tumour cells, suggesting that Ca2+ signaling is not a general feature of cell–cell encounters. Similarly, leukocytes demonstrate Ca2+ signals during contact with trophoblast cell lines. Ca2+ signals were confirmed using three dyes and with the Ca2+ buffer BAPTA.

Conclusion  We suggest that leukocyte‐to‐trophoblast interactions lead to mutual Ca2+ signaling events in both cell types, which may contribute to immunoregulation at the materno–fetal interface.
REVIEW ARTICLE: Toll‐Like Receptors at the Maternal–Fetal Interface in Normal Pregnancy and Pregnancy Disorders
Authors: Koga Kaori , Mor Gil
Published: March 2010

Citation Koga K, Mor G. Toll‐like receptors at the maternal–fetal interface in normal pregnancy and pregnancy disorders. Am J Reprod Immunol 2010

Toll‐like receptors (TLR) form the major family of pattern recognition receptors (PRR) that are involved in innate immunity. Innate immune responses against microorganisms at the maternal–fetal interface may have a significant impact on the success of pregnancy, as intrauterine infections have been shown to be strongly associated with certain disorders of pregnancy. At the maternal–fetal interface, TLRs are expressed not only in the immune cells but also in non‐immune cells such as trophoblasts and decidual cells; moreover, their expression patterns vary according to the stage of pregnancy. Here, we will describe potential functions of TLRs in these cells, their recognition and response to microorganisms, and their involvement in the innate immunity. The impact of TLR‐mediated innate immune response will be discussed via animal model studies, as well as clinical observations.
The Modern Industrial Revolution, Exit, and the Failure of Internal Control Systems
Authors: Jensen Michael C.
Published: March 2010

This article, which is based on the author's Presidential address to the American Finance Association in 1993, argues that squeezing out excess capital and capacity is one of the most formidable ongoing challenges facing not only the U.S. economy, but the economies of all industrialized nations. In making this argument, the article draws striking parallels between the 19th‐century industrial revolution and worldwide economic developments in the last three decades. In both periods, technological advances led to not only sharp increases in productivity and dramatic reductions in prices, but also massive obsolescence and overcapacity. And much as the great M&A wave of the 1890s reduced capacity by consolidating some 1,800 companies into roughly 150, the leveraged takeovers, LBOs, and other leveraged recapitalizations of the 1980s provided “healthy adjustments” to overcapacity that was building in many sectors of the U.S. economy.

To help public companies make the necessary adjustments to overcapacity, the author urges them to consider adopting some of the features of private equity, including significant equity stakes for managers, high leverage or payouts, and the recruiting of active investors as “partners in the business.”
Just Say No to Wall Street: Putting a Stop to the Earnings Game
Authors: Fuller Joseph , Jensen Michael C.
Published: March 2010

CEOs and CFOs put themselves in a bind by providing earnings guidance and then making decisions designed to meet Wall Street's expectations for quarterly earnings. When earnings appear to be coming in short of projections, top managers often react by suggesting or demanding that middle and lower level managers redo their forecasts, plans, and budgets. In some cases, top executives simply acquiesce to increasingly unrealistic analyst forecasts and adopt them as the basis for setting organizational goals and developing internal budgets. But in cases where external expectations are impossible to meet, either approach sets up the firm and its managers for failure.

Using the experiences of several companies, the authors illustrate the dangers of conforming to market pressures for unrealistic growth targets. They argue that an overvalued stock, by encouraging overpriced acquisitions and other risky, value‐destroying bets, can be as damaging to the long‐run health of a company as an undervalued stock.

Putting an end to the “earnings game” requires that CEOs reclaim the initiative by avoiding earnings guidance and managing expectations in such a way that their stocks trade reasonably close to their intrinsic value. In place of earnings forecasts, management should provide information about the company's strategic goals and main value drivers. They should also talk about the risks associated with the strategies, and management's plans to deal with them.
Are Incentives the Bricks or the Building?
Authors: Schmidt Ron
Published: March 2010

The efforts of economists to emphasize the importance of incentives as determinants of organizational performance, while successful to some degree, may have left the mistaken impression that “getting the incentives right” is the only task requiring the attention of senior executives when designing corporate organizations. The author identifies the incentive‐intensive companies envisioned by economists as “mercenary organizations” (or MOs), or companies whose distinguishing feature is near‐complete reliance on financial rewards and controls. Citing the difficulties of devising an effective incentive system that cannot be gamed (which he calls the organizational equivalent of “an anti‐gravity machine”), the article questions whether such organizations are likely to yield superior performance.

As an alternative to paying more attention to incentive design, the author suggests devoting more corporate resources to seeking and attracting individuals with low “monitoring costs.” After holding up examples of top executives who appear committed to that search, the author posits a “character‐rich” organization (CRO) as an alternative to the MO of the economists.

Then, viewing all companies as occupying points on a continuum with the MO and CRO as its poles, the author argues that all companies combine elements of both kinds of organizations. And perhaps most important, the CEOs of many of the most successful large organizations, without minimizing the importance of incentives, pay even greater attention to the search for trustworthy individuals and the creation of a culture of teamwork and accountability.
Early signs and symptoms of psychosis among Palauan adolescents
Authors: Madraisau Sheri , Tomoichi Ulai , Ord Lisa M. , Florsheim Paul , Phillips Lisa J. , Blailes Francisca , Basilius Merlyn , Kuartei Stevenson , Tiobech Josepha , Myles‐Worsley Marina , Ngiralmau Hilda
Published: March 2010

Aim: This study was designed to identify early symptoms associated with the occurrence of psychosis during adolescence.

Method: Participants were recruited in the Republic of Palau, an isolated island nation in Micronesia with a prevalence rate for schizophrenia of 1.99%. Diagnostic interviews were used to obtain reports of early and current symptoms from 112 genetically high‐risk (GHR) and 208 genetically low‐risk (GLR) adolescents (ages 16–23). Based on current psychotic symptoms, participants were sorted into three groups: non‐clinical, at‐risk/symptomatic risk and clinically symptomatic.

Results: Multivariate analysis of variance revealed several between‐group differences on rates of early symptoms. Most notably, youth who were in the GHR‐clinically symptomatic group reported significantly higher rates of early marijuana use than GLR‐clinically symptomatic youth, who were significantly more likely to report early symptoms of depression and behaviour disorders. In addition, several gender based differences in the link between early symptoms and adolescent onset psychosis were noted.

Conclusions: Findings are generally consistent with previous research on early indicators, though several unexpected findings suggest that results from this study may not be fully generalizable beyond this relatively isolated and culturally distinct Micronesian nation.
Cost‐Effectiveness of Family‐Based Substance Abuse Treatment
Authors: Morgan Triston B. , Crane D. Russell
Published: March 2010

In order to compete in a financially sensitive health care system, family systems–based treatments must demonstrate effective clinical results as well as cost‐effectiveness. Cost‐effectiveness research can demonstrate to health care insurers and policy makers which treatments are viable options for implementation. The present literature review identified eight cost‐effectiveness family‐based substance abuse treatment studies. The results suggest that certain family‐based treatments are cost‐effective and warrant consideration for inclusion in health care delivery systems.
Public health and collaborative governance
Authors: Fierlbeck Katherine
Published: March 2010

Abstract: The nature of governance in Canada, both horizontally (between federal departments) and vertically (between federal and provincial governments) is changing. Or is it? Two distinct trends seem to have emerged over the past decade: one towards horizontal coordination and one towards vertical collaboration. These trends are perhaps best exemplified by the Public Health Agency of Canada, which depends very emphatically on integrated relationships both with other federal departments and with provincial and territorial governments. Yet in the past year, severe criticisms have emerged regarding the agency's ability to meet its objectives. To what extent are these problems due to the failure of collaborative governance? On a wider level, have decision‐makers been too insouciant about making importunate public policy decisions on an assumption of the viability of collaborative governance? This article argues that problems in vertical collaboration in public health have occurred largely due to failures in horizontal coordination within the national government.
Standards of judicial review of administrative bodies: The consideration of citizen participation
Authors: Taucar Christopher Edward
Published: March 2010

Abstract: In Canada there is little legitimate or legal room or consistency with the judicial role in judicial review of or appeal from administrative actions or decisions for courts to take into account the degree or quality of citizen participation to support greater deference for administrative decision or action. At most, this consideration may be considered a sub‐factor, marginal and never determinative. In particular, citizen participation can be a sub‐factor when the public perception is either explicitly central to the legislation in issue, or is assumed or inferred as such by the court. Nevertheless, assuming such citizen participation in bureaucracy is positive, there can be some significant indirect coincidental promotion of it in reality as a result of and through judicial deference to administrative decisions, which occurs concomitantly in standard‐of‐review analysis.
Auditing citizen engagement in heritage planning: The views of citizens
Authors: MacMillan C. Michael
Published: March 2010

Abstract: Drawing the citizen back into public fora has become the issue of the day in democratic countries around the globe. On the political stage, there is growing alarm over a perceived “democratic deficit,” which has inspired a variety of innovative means of engaging citizens in public policy decisions. This plethora of engagement mechanisms invites the question of how citizens evaluate these engagement opportunities, a question that reveals a decided lacuna of studies regarding citizen assessments of these various mechanisms. This study is a report from the citizen participants on the merits of a Nova Scotia model of citizen engagement in policy development. It examines a citizen task force organized by Voluntary Planning, which conducted a citizen consultation process to create policy recommendations for heritage preservation in Nova Scotia, using its distinctive technique of citizen engagement. This study is the first evaluation of the Nova Scotia process from the perspective of citizen participants conducted to date. It concludes that the process used is highly regarded and enhances the legitimacy of such mechanisms as the “voice of the people” for citizens themselves and government decision‐makers.
SYSTEMATIC REVIEW: Surgical Maze Procedure as a Treatment for Atrial Fibrillation: A Meta‐Analysis of Randomized Controlled Trials
Authors: Kong Melissa H. , Lopes Renato D. , Piccini Jonathan P. , Hasselblad Vic , Bahnson Tristram D. , Al‐Khatib Sana M.
Published: March 2010

Surgical or modified Maze procedures have been promoted to treat atrial fibrillation (AF); however, few randomized controlled clinical trials (RCTs) examine their outcomes. The purpose of this meta‐analysis is to compare the efficacy of surgical Maze procedures performed concomitantly with referral cardiac surgery versus pharmacologic therapy for the treatment of AF. We searched MEDLINE, Cochrane database, FDA web‐portal, and clinicaltrials.gov for all RCTs comparing surgical Maze procedures with medical therapy for sinus rhythm maintenance. Primary outcomes were either freedom from AF within 12 months postprocedure off antiarrhythmic drug (AAD), or freedom from AF while taking an AAD. Secondary outcomes included operative mortality, all‐cause mortality, hospital length of stay, and postoperative complications. Both fixed‐ and random‐effects models were used for a meta‐analysis of 9 randomized controlled trials (n = 472, of which 249 underwent a Maze procedure and 213 underwent referral surgery alone). The surgical Maze procedure significantly increased the odds of freedom from AF within 12 months compared with cardiac surgery alone (OR 5.22, 95% CI 1.71–15.88). There was significant heterogeneity among the trials for freedom from AF (chi‐square = 15.98 for 4 degrees of freedom, P= 0.003). Among the two studies that fully reported AAD use, there was no evidence of improved survival free from AF and AAD therapy (OR 1.78, 95% CI 0.73–4.34). Among patients with valvular AF, surgical Maze procedures are associated with a decrease in AF one year postprocedure without significant increase in mean length of hospital stay, perioperative complications, operative, or all‐cause mortality. Large RCTs defining rates of freedom from AF without AADs postprocedure, are still needed to evaluate outcomes and determine the appropriate role for surgical Maze procedures in the management of AF.
Internal ribosomal entry‐site activities of clinical isolate‐derived hepatitis A virus and inhibitory effects of amantadine
Authors: Kanda Tatsuo , Imazeki Fumio , Nakamoto Shingo , Okitsu Kohichiroh , Fujiwara Keiichi , Yokosuka Osamu
Published: March 2010

Aim:  Little is known about specific naturally‐occurring internal ribosomal entry site (IRES) activities of hepatitis A virus (HAV). We examined these activities using the bicistronic reporter assay and the effects of antiviral amantadine against their activities.

Methods:  Six HAV IRES clones from three patients with fulminant hepatitis and three with self‐limited acute hepatitis were obtained. The activities of their IRES were analyzed using bicistronic reporter assay in hepatocyte‐ and non‐hepatocyte‐derived cell lines, and the potential efficaciousness of the amantadine was examined.

Results:  One clone from fulminant hepatitis had a deletion in domains III–IV of HAV IRES had higher IRES activities than HM175 in HLE and Huh‐7 cells. In Huh‐7 cells, amantadine is effective for inhibiting HAV IRES activities, and especially fulminant hepatitis‐derived ones.

Conclusion:  HAV IRES derived from clinical isolates have various activities. Bicistronic reporter assay using clinical isolates may be another useful tool for testing antiviral activities like those of amantadine and the new acridines and hydrazones recently reported.
Chemical Strengthening of Glass: Lessons Learned and Yet To Be Learned
Authors: Varshneya Arun K.
Published: March 2010

This paper reviews the progress that has been made in our understanding of the chemical strengthening of glass by ion exchange over its nearly five decades of history. Lessons learned are briefly discussed; more importantly, those which are yet to be learned are highlighted. It is recognized that, except for detailed compositional effects, the kinetics of ion interdiffusion process and the chemical strengthening technology are reasonably well understood. However, the science of stress generation and its concurrent relaxation is far from being clear despite the elegant analogy to thermal stresses invoked by Cooper. The need to understand plasticity of glass network during accommodation of a larger invading ion is emphasized. In turn, the influence of network topology on its yield strength in shear as well as hydrostatic modes is recognized. For expanded applications under extreme conditions of loading, damage evolution in chemically strengthened glass needs to be studied. Such a study is linked to our understanding of the terms “strength,”“hardness,”“toughness,” and “brittleness” of glass.
Periodic Transition on an Axial Compressor Stator: Incidence and Clocking Effects: Part II—Transition Onset Predictions
Authors: Solomon W. J. , Walker G. J. , Hughes J. D.
Published: March 2010

Transition onset observations from a 1.5-stage axial compressor outlet stator presented in Part I of this paper are compared with the predictions of conventional transition correlations applied in a quasi-steady manner. The viscous/inviscid interaction code MISES is used to predict the blade surface pressure distributions and boundary layer development. The temporal variation in transition onset is then predicted using ensemble-averaged free-stream turbulence data from the compressor measurements. This simple procedure captures most significant features of the complex transition process on the compressor, and is clearly superior to fixed transition models based on long-term average free-stream turbulence levels. Parallel computations for both natural and bypass transition modes indicate that the natural transition mode tends to dominate on the compressor. This is at variance with turbine airfoil experience, where bypass transition is clearly more important. Comparison of prediction and experiment highlights the significance of leading edge potential flow interactions in promoting periodic wake-induced transition. Viscous/inviscid interactions in the neighborhood of transition can also have an important influence on boundary layer stability and separation phenomena.
Design and Testing of Swept and Leaned Outlet Guide Vanes to Reduce Stator–Strut–Splitter Aerodynamic Flow Interactions
Authors: Wadia A. R. , Szucs P. N. , Gundy-Burlet K. L.
Published: March 2010

Large circumferentially varying pressure levels produced by aerodynamic flow interactions between downstream stators and struts present a potential noise and stability margin liability in a compression component. These interactions are presently controlled by tailoring the camber and/or stagger angles of vanes neighboring the fan frame struts. This paper reports on the design and testing of a unique set of swept and leaned fan outlet guide vanes (OGVs) that do not require this local tailoring even though the OGVs are closely coupled with the fan frame struts and splitter to reduce engine length. The swept and leaned OGVs not only reduce core-duct diffusion, but they also reduce the potential flow interaction between the stator and the strut relative to that produced by conventional radial OGVs. First, the design of the outlet guide vanes using a single blade row three-dimensional viscous flow analysis is outlined. Next, a two-dimensional potential flow analysis was used for the coupled OGV–frame system to obtain a circumferentially nonuniform stator stagger angle distribution to reduce the upstream static pressure disturbance further. Recognizing the limitations of the two-dimensional potential flow analysis for this highly three-dimensional set of leaned OGVs, as a final evaluation of the OGV–strut system design, a full three-dimensional viscous analysis of a periodic circumferential sector of the OGVs, including the fan frame struts and splitter, was performed. The computer model was derived from a NASA-developed code used in simulating the flow field for external aerodynamic applications with complex geometries. The three-dimensional coupled OGV–frame analysis included the uniformly staggered OGV configuration and the variably staggered OGV configuration determined by the two-dimensional potential flow analysis. Contrary to the two-dimensional calculations, the three-dimensional analysis revealed significant flow problems with the variably staggered OGV configuration and showed less upstream flow nonuniformity with the uniformly staggered OGV configuration. The flow redistribution in both the radial and tangential directions, captured fully only in the three-dimensional analysis, was identified as the prime contributor to the lower flow nonuniformity with the uniformly staggered OGV configuration. The coupled three-dimensional analysis was also used to validate the design at off-design conditions. Engine test performance and stability measurements with both uniformly and variably staggered OGV configurations with and without the presence of inlet distortion confirmed the conclusions from the three-dimensional analysis.
Simulation of Vortex Shedding in a Turbine Stage
Authors: Sondak D. L. , Dorney D. J.
Published: March 2010

Vortex shedding in a turbomachine blade row is affected by the passing of blades in the adjacent downstream blade row, but these effects have not been examined in the literature. A series of flow simulations has been performed to study vortex shedding in a turbine stage, and to quantify the blade interaction effects on the unsteady pressure response. The numerical issues of spatial order of accuracy and the use of Newton subiterations were investigated first. Second-order spatial accuracy was shown to be inadequate to model the shedding frequency response and time-averaged base pressure accurately. For the small time step employed for temporal accuracy, Newton iterations were shown to be unnecessary. The effects of the adjacent blade row were examined by comparing the shedding frequency response for the stage simulations to the response for isolated cascades. The vane shedding was shown to occur exactly on a series of harmonics of the blade passing frequency for the stage case, compared to a single predominant frequency for the isolated cascade. Losses were also examined in the wake region. It was shown that close to the trailing edge, losses were mainly due to wake mixing. Farther downstream of the trailing edge, losses were predominantly due to the trailing edge shock wave.
Unsteady Heat Transfer in Stator–Rotor Interaction by Two-Equation Turbulence Model
Authors: Michelassi V. , Martelli F. , De´nos R. , Arts T. , Sieverding C. H.
Published: March 2010

A transonic turbine stage is computed by means of an unsteady Navier–Stokes solver. A two-equation turbulence model is coupled to a transition model based on integral parameters and an extra transport equation. The transonic stage is modeled in two dimensions with a variable span height for the rotor row. The analysis of the transonic turbine stage with stator trailing edge coolant ejection is carried out to compute the unsteady pressure and heat transfer distribution on the rotor blade under variable operating conditions. The stator coolant ejection allows the total pressure losses to be reduced, although no significant effects on the rotor heat transfer are found both in the computer simulation and the measurements. The results compare favorably with experiments in terms of both pressure distribution and heat transfer around the rotor blade.
Dual-Laser Probe Measurement of Blade-Tip Clearance
Authors: Dhadwal H. S. , Kurkov A. P.
Published: March 2010

This paper describes two dual-laser probe integrated fiber optic systems for measuring blade tip clearance in rotating turbomachinery. The probes are nearly flush with the casing inner lining, resulting in minimal flow disturbance. The two probes are closely spaced in a circumferential plane and are slanted at an angle relative to each other so that the blade tip traverse time of the space between the two laser beams varies with the tip radius, allowing determination of the tip clearance at the rotor operating conditions. The tip clearance can be obtained for all the blades in a rotor with a single system, provided there are no synchronous vibrations present at a particular operating condition. These probes were installed in two holders; one provided an included angle between the probes of 20 deg, and the other provided an included angle of 40 deg. The two configurations were calibrated in a vacuum spin rig facility that is capable of reproducing realistic blade tip speeds.
The Influence of Shrouded Stator Cavity Flows on Multistage Compressor Performance
Authors: Wellborn S. R. , Okiishi T. H.
Published: March 2010

Experiments were performed on a low-speed multistage axial-flow compressor to assess the effects of shrouded stator cavity flows on aerodynamic performance. Five configurations, which involved systematic changes in seal-tooth leakage rates and/or elimination of the shrouded stator cavities, were tested. Rig data indicate increasing seal-tooth leakage substantially degraded compressor performance. For every 1 percent increase in seal-tooth clearance-to-span ratio, the decrease in pressure rise was 3 percent and the reduction in efficiency was 1 point. These observed performance penalties are comparable to those commonly reported for rotor and cantilevered stator tip clearance variations. The performance degradation observed with increased leakage was brought about in two distinct ways. First, increasing seal-tooth leakage directly spoiled the near-hub performance of the stator row in which leakage occurred. Second, the altered stator exit flow conditions, caused by increased leakage, impaired the performance of the next downstream stage by decreasing the work input of the rotor and increasing total pressure loss of the stator. These trends caused the performance of downstream stages to deteriorate progressively. Numerical simulations of the test rig stator flow field were also conducted to help resolve important fluid mechanic details associated with the interaction between the primary and cavity flows. Simulation results show that fluid originating in the upstream cavity collected on the stator suction surface when the cavity tangential momentum was low and on the pressure side when it was high. The convection of cavity fluid to the suction surface was a mechanism that reduced stator performance when leakage increased.
Rotating Stall Control in a High-Speed Stage With Inlet Distortion: Part I—Radial Distortion
Authors: Spakovszky Z. S. , Weigl H. J. , Paduano J. D. , van Schalkwyk C. M. , Suder K. L. , Bright M. M.
Published: March 2010

This paper presents the first attempt to stabilize rotating stall in a single-stage transonic axial flow compressor with inlet distortion using active feedback control. The experiments were conducted at the NASA Lewis Research Center on a single-stage transonic core compressor inlet stage. An annular array of 12 jet-injectors located upstream of the rotor tip was used for forced response testing and to extend the compressor stable operating range. Results for radial distortion are reported in this paper. First, the effects of radial distortion on the compressor performance and the dynamic behavior were investigated. Control laws were designed using empirical transfer function estimates determined from forced response results. The transfer functions indicated that the compressor dynamics are decoupled with radial inlet distortion, as they are for the case of undistorted inlet flow. Single-input-single-output (SISO) control strategies were therefore used for the radial distortion controller designs. Steady axisymmetric injection of 4 percent of the compressor mass flow resulted in a reduction in stalling mass flow of 9.7 percent relative to the case with inlet distortion and no injection. Use of a robust H∞ controller with unsteady nonaxisymmetric injection achieved a further reduction in stalling mass flow of 7.5 percent, resulting in a total reduction of 17.2 percent.
Physics of Hot Crossflow Ingestion in Film Cooling
Authors: McGrath E. L. , Leylek J. H.
Published: March 2010

Computational fluid dynamics (CFD) is used to isolate the flow physics responsible for hot crossflow ingestion, a phenomenon that can cause failure of a film cooled gas turbine component. In the gas turbine industry, new compound-angle shaped hole (CASH) geometries are currently being developed to decrease the heat transfer coefficient and increase the adiabatic effectiveness on film cooled surfaces. These new CASH geometries can have unexpected flow patterns that result in hot crossflow ingestion at the film hole. This investigation examines a 15 deg forward-diffused film hole injected streamwise at 35 deg with a compound angle of 60 deg (FDIFF60) and with a length-to-diameter ratio (L/D) of 4.0. Qualitative and quantitative aspects of computed results agreed well with measurements, thus lending credibility to predictions. The FDIFF60 configuration is a good representative of a typical CASH geometry, and produces flow mechanisms that are characteristic of CASH film cooling. FDIFF60 has been shown to have impressive downstream film cooling performance, while simultaneously having undesirable ingestion at the film hole. In addition to identifying the physical mechanisms driving ingestion, this paper documents the effects on ingestion of the blowing ratio, the density ratio, and the film hole Reynolds number over realistic gas turbine ranges of 0.5 to 1.88, 1.6 to 2.0, and 17,350 to 70,000, respectively. The results of this study show that hot crossflow ingestion is caused by a combination of coolant blockage at the film hole exit plane and of crossflow boundary layer vorticity that has been re-oriented streamwise by the presence of jetting coolant. Ingestion results when this re-oriented vorticity passes over the blocked region of the film hole. The density ratio and the film hole Reynolds number do not have a significant effect on ingestion over the ranges studied, but the blowing ratio has a surprising nonlinear effect. Another important result of this study is that the blockage of coolant hampers convection and allows diffusion to transfer heat into the film hole even when ingestion is not present. This produces both an undesirable temperature gradient and high temperature level on the film hole wall itself. Lessons learned about the physics of ingestion are generalized to arbitrary CASH configurations. The systematic computational methodology currently used has been previously documented and has become a standard for ensuring accurate results. The methodology includes exact modeling of flow physics, proper modeling of the geometry including the crossflow, plenum, and film hole regions, a high quality mesh for grid independent results, second order discretization, and the two-equation k–ε turbulence model with generalized wall functions. The steady, Reynolds-averaged Navier–Stokes equations are solved using a fully elliptic and fully implicit pressure-correction solver with multiblock unstructured and adaptive grid capability and with multigrid convergence acceleration.
A Theory for Predicting the Turbulent-Spot Production Rate
Authors: Mayle R. E.
Published: March 2010

A theory is presented for predicting the production rate of turbulent spots. The theory, based on that by Mayle–Schulz for bypass transition, leads to a new correlation for the spot production rate in boundary layer flows with a zero pressure gradient. The correlation, which agrees reasonably well with data, clearly shows the effects of both free-stream turbulence level and length scale. In addition, the theory provides an estimate for the lowest level of free-stream turbulence causing bypass transition.
Comparison of Measurement Data at the Impeller Exit of a Centrifugal Compressor Measured With Both Pneumatic and Fast-Response Probes
Authors: Roduner C. , Ko¨ppel P. , Kupferschmied P. , Gyarmathy G.
Published: March 2010

The main goal of these investigations was the refined measurement of unsteady high-speed flow in a centrifugal compressor using the advanced FRAP® fast-response aerodynamic probe system. The present contribution focuses on the impeller exit region and shows critical comparisons between fast-response (time-resolving) and conventional pneumatic probe measurement results. Three probes of identical external geometry (one fast and two pneumatic) were used to perform wall-to-wall traverses close to the impeller exit. The data shown refer to a single running condition near the best point of the stage. The mass flow obtained from different probe measurements and from the standard orifice measurement were compared. Stage work obtained from temperature rise measured with a FRAP® probe and from impeller outlet velocity vectors fields by using Euler’s turbine equation are presented. The comparison in terms of velocity magnitude and angle distribution is quite satisfactory, indicating the superior DC measurement capabilities of the fast-response probe system.
The Effect of Inlet Boundary Layer Thickness on the Flow Within an Annular S-Shaped Duct
Authors: Sonoda T. , Arima T. , Oana M.
Published: March 2010

Experimental and numerical investigations were carried out to gain a better understanding of the flow characteristics within an annular S-shaped duct, including the effect of the inlet boundary layer (IBL) on the flow. A duct with six struts and the same geometry as that used to connect compressor spools on our experimental small two-spool turbofan engine was investigated. A curved downstream annular passage with a similar meridional flow path geometry to that of the centrifugal compressor has been fitted at the exit of S-shaped duct. Two types of the IBL (i.e., thin and thick IBL) were used. Results showed that large differences of flow pattern were observed at the S-shaped duct exit between two types of the IBL, though the value of “net” total pressure loss has not been remarkably changed. According to “overall” total pressure loss, which includes the IBL loss, the total pressure loss was greatly increased near the hub as compared to that for a thin one. For the thick IBL, a vortex pair related to the hub-side horseshoe vortex and the separated flow found at the strut trailing edge has been clearly captured in the form of the total pressure loss contours and secondary flow vectors, experimentally and numerically. The high-pressure loss regions on either side of the strut wake near the hub may act on a downstream compressor as a large inlet distortion, and strongly affect the downstream compressor performance. There is a much-distorted three-dimensional flow pattern at the exit of S-shaped duct. This means that the aerodynamic sensitivity of S-shaped duct to the IBL thickness is very high. Therefore, sufficient care is needed to design not only downstream aerodynamic components (for example, centrifugal impeller) but also upstream aerodynamic components (LPC OGV).
Theoretical and Uniaxial Experimental Evaluation of Human Annulus Fibrosus Degeneration
Authors: O’Connell Grace D. , Guerin Heather L. , Elliott Dawn M.
Published: March 2010

The highly organized structure and composition of the annulus fibrosus provides the tissue with mechanical behaviors that include anisotropy and nonlinearity. Mathematical models are necessary to interpret and elucidate the meaning of directly measured mechanical properties and to understand the structure-function relationships of the tissue components, namely, the fibers and extrafibrillar matrix. This study models the annulus fibrosus as a combination of strain energy functions describing the fibers, matrix, and their interactions. The objective was to quantify the behavior of both nondegenerate and degenerate annulus fibrosus tissue using uniaxial tensile experimental data. Mechanical testing was performed with samples oriented along the circumferential, axial, and radial directions. For samples oriented along the radial direction, the toe-region modulus was 2× stiffer with degeneration. However, no other differences in measured mechanical properties were observed with degeneration. The constitutive model fit well to samples oriented along the radial and circumferential directions (R2≥0.97). The fibers supported the highest proportion of stress for circumferential loading at 60%. There was a 70% decrease in the matrix contribution to stress from the toe-region to the linear-region of both the nondegenerate and degenerate tissue. The shear fiber-matrix interaction (FMI) contribution increased by 80% with degeneration in the linear-region. Samples oriented along the radial and axial direction behaved similarly under uniaxial tension (modulus=0.32 MPa versus 0.37 MPa), suggesting that uniaxial testing in the axial direction is not appropriate for quantifying the mechanics of a fiber reinforcement in the annulus. In conclusion, the structurally motivated nonlinear anisotropic hyperelastic constitutive model helps to further understand the effect of microstructural changes with degeneration, suggesting that remodeling in the subcomponents (i.e., the collagen fiber, matrix and FMI) may minimize the overall effects on mechanical function of the bulk material with degeneration.
Recruitment Viscoelasticity of the Tendon
Authors: Raz Einat , Lanir Yoram
Published: March 2010

There is still no agreement on the nature of tissues' viscoelasticity and on its reliable modeling. We speculate that disagreements between previous observations stem from difficulties of separating between viscoelastic and preconditioning effects, since both are manifested by similar response features. Here, this and related issues were studied in the tendon as a prototype for other soft tissues. Sheep digital tendons were preconditioned under strain that was higher by 1% than the one used in subsequent testing. Each specimen was then subjected to stress relaxation, and quick release or creep. A stochastic microstructural viscoelastic theory was developed based on the collagen fibers' properties and on their gradual recruitment with stretch. Model parameters were estimated from stress relaxation data and predictions were compared with the creep data. Following its validation, the new recruitment viscoelasticity (RVE) model was compared, both theoretically and experimentally, with the quasilinear viscoelastic (QLV) theory. The applied preconditioning protocol produced subsequent pure viscoelastic response. The proposed RVE model provided excellent fit to both stress relaxation and creep data. Both analytical and numerical comparisons showed that the new RVE theory and the popular QLV one are equivalent under deformation schemes at which no fibers buckle. Otherwise, the equivalence breaks down; QLV may predict negative stress, in contrast to data of the quick release tests, while RVE predicts no such negative stress. The results are consistent with the following conclusions: (1) fully preconditioned tendon exhibits pure viscoelastic response, (2) nonlinearity of the tendon viscoelasticity is induced by gradual recruitment of its fibers, (3) a new structure-based RVE theory is a reliable representation of the tendon viscoelastic properties under both stress relaxation and creep tests, and (4) the QLV theory is equivalent to the RVE one (and valid) only under deformations in which no fibers buckle. The results also suggest that the collagen fibers themselves are linear viscoelastic.
Direct observation of interaction between proteins and blood-compatible polymer surfaces
Authors: Hayashi Tomohiro , Tanaka Masaru , Yamamoto Sadaaki , Shimomura Masatsugu , Hara Masahiko
Published: March 2010

The adhesion force between blood-compatible polymer (poly(2-methoxyethyl acrylate: PMEA) and proteins (fibrinogen and bovine serum albumin (BSA)) were measured by atomic force microscopy. The PMEA surface showed almost no adhesion to native protein molecules, whereas non-blood-compatible poly (n-butyl acrylate): PBA strongly adhered to proteins. Interestingly, adhesion did appear between PMEA and proteins when the proteins were denatured. In all cases, these trends were not affected by the conditions of the solution. Combining the results with previous reports, the authors conclude that interfacial water molecules play a critical role in the protein resistance of PMEA.
Peptide-presenting two-dimensional protein matrix on supported lipid bilayers: An efficient platform for cell adhesion
Authors: Bérat Rémi , Rémy-Zolghadry Murielle , Gounou Céline , Manigand Claude , Tan Sisareuth , Saltó Carmen , Arenas Ernest , Bordenave Laurence , Brisson Alain R.
Published: March 2010

Understanding and controlling cell adhesion to biomaterials and synthetic materials are important issues in basic research and applied sciences. Supported lipid bilayers (SLBs) functionalized with cell adhesion peptides linked to lipid molecules are popular platforms of cell adhesion. In this paper, an alternative approach of peptide presentation is presented in which peptides are stereo-selectively linked to proteins self-assembling in a rigid two-dimensional (2D) matrix on SLBs. Annexin-A5 (Anx5) was used as prototype protein for its known properties of forming stable and rigid 2D matrices on lipid surfaces. Two types of Anx5-peptide complexes, containing either a RGD or an IKVAV sequence, were synthesized. The authors show that both Anx5-peptide complexes present the same properties of binding and 2D organization on lipid surfaces as Anx5, when investigated by quartz crystal microbalance with dissipation monitoring, atomic force microscopy, and transmission electron microscopy techniques. Anx5-RGD and Anx5-IKVAV 2D matrices were found to promote specific adhesion of human saphenous vein endothelial cells and mouse embryonic stem cells, respectively. The influence of the surface density of exposed peptides on cell adhesion was investigated, showing that cells attach to Anx5-peptide matrices when the average distance between peptides is smaller than about 60 nm. This cell adhesion platform provides control of the orientation and density of cell ligands, opening interesting possibilities for future applications.
Synthesis and electron emission properties of MgO nanowires
Authors: Tan Huabing , Xu Ningsheng , Deng Shaozhi
Published: March 2010

Magnesium oxide film has high secondary electron emission yield and is found as applications in flat panel display widely. In this work, MgO nanowire electron emission properties, including both secondary and field emissions, are reported. MgO nanowire thin films have been synthesized on stainless steel substrate by thermal vapor deposition. The turn-on field of 9 MV/m for the field emission is measured with the MgO nanowire thin film, and the maximum secondary electron emission (SEE) yield of 8.3 is obtained. In addition, the good stability of SEE yield is also observed under long-time electron bombardment.
Electron emission from LiNbO3 crystal excited by ultraviolet laser
Authors: Kisa T. , Murakami K. , Abo S. , Wakaya F. , Takai M. , Ishida T.
Published: March 2010

X-ray generation by a thermally heated LiNbO3 crystal and effect of ultraviolet (UV) laser light irradiation to a LiNbO3 crystal on pyroelectric electron emission were investigated. The x ray was detected with a gap distance of 15 mm between the surface of the crystal and the anode, whereas it was not detected with a gap distance of ∼200 μm. The dependence of the electron emission excited by UV laser irradiation on the vacuum pressure, laser power density, and gap distance between the crystal and the anode was measured. The electron emission showed a fast response with a rise time of 1 μs to the laser irradiation. The emission current was 45 nA with a laser power density of 6.6 MW/cm2 with a gap distance of 125 μm between the surface of the crystal and the anode.
Wide-dynamic-range, fast-response CBr4 doping system for molecular beam epitaxy
Authors: Chang Yu-Chia , Zheng Yan , English John H. , Jackson Andrew W. , Coldren Larry A.
Published: March 2010

The authors report the design and performance of a versatile carbon doping system for solid-source molecular beam epitaxy using carbon tetrabromide (CBr4). This system is capable to achieve three orders of magnitude in doping by changing the CBr4 temperature along with varying the CBr4 leak rate into the growth chamber. The CBr4 temperature is controlled using thermoelectric coolers and thus can be adjusted easily and quickly. The CBr4 vapor pressure increases more than 1 decade when its temperature increases from −5 to 20 °C. The CBr4 leak rate is controlled using six different diameter orifices connected in parallel, and the flow to each orifice can be switched on and off independently using a pneumatic valve. The fast response time of these pneumatic valves enables us to change the doping abruptly. This system is suitable for growing sophisticated structures, which require wide doping range and fast changes in doping.
A CLASSIFICATION OF HYPERSURFACES WITH PARALLEL PARA-BLASCHKE TENSOR IN Sm+1
Authors: CHENG QING-MING , LI XINGXIAO , QI XUERONG
Published: March 2010

In this paper, we classify all immersed hypersurfaces in the unit sphere Sm+1 with parallel para-Blaschke tensor.
CRITICAL DOMAINS OF THE EIGENVALUE RATIOS OF THE DIRICHLET LAPLACIAN
Authors: HOU SONGBO
Published: March 2010

This paper contained mathematical errors and its publication is retracted from IJM. Please contact ijm@wspc.com
FIRST PRINCIPLES STUDY OF ELECTRONIC STRUCTURE AND MAGNETIC PROPERTIES OF HALF-METALLIC FULL-HEUSLER ALLOYS Co2MnSi and Co2FeSi
Authors: QI JINGSHAN , YU HAILIN , JIANG XUEFAN , SHI DANING
Published: March 2010

We present a comprehensive investigation of the equilibrium structural, electronic and magnetic properties of C o2 MnSi and C o2 FeSi by density-functional theory (DFT) within the generalized gradient approximation (GGA) using the projected augmented wave (PAW) method. The on-site Coulomb interaction has also taken into account ( GGA +U) approach to unravel the correlation effects on the electronic structure. The change of the energy gap, "spin gap", Fermi energy level and magnetic moments with the lattice parameters is investigated. We found that the on-site correlation interaction in C o2 FeSi is stronger than in C o2 MnSi . So on-site electronic correlation is necessary for C o2 FeSi and the magnetic moments reproduce experimental results well by GGA +U. Further we also found that a moderate change of the lattice parameters does not change the half-metallic ferromagnet (HMF) behavior for both materials. Appearance of half-metallicity is consistent with the integral magnetic moments, which also agrees with the experiment measurements.