bluuebunny/crossref_metadata_2025 huggingface dataset:
‘Don't speak like that to her!’: Linguistic minority children's socialization into an ideology of monolingualism
Authors: Karrebæk Martha Sif
Published: June 2013

It is of general interest to the study of language in society how ideologies motivating linguistic hegemony get formulated in the context of increasing diversity. This includes if and how linguistic diversity surfaces under conditions that are clearly disfavouring it, and why or why not it happens. Also, we need to know how ideologies of language surface at the micro‐level, and how they are continuously passed on, shared, negotiated or contested. These are central issues in this study of socialization into a condition and an ideology of linguistic hegemony in Copenhagen, Denmark. It is illustrated how school‐authorities, parents and children co‐create Danish dominance and a linguistic ideology of monolingualism during the first school year. The primary focus is on two school‐beginners with minority language background in a linguistically diverse classroom, and the linguistic registers of particular interest are Danish, the majority language, and Turkish, an immigrant language. The article builds on field‐notes, ethnographic interviews, video‐ and audio‐recordings. Linguistic Ethnography and Language Socialization constitute the methodological frameworks, and Silverstein's ‘total linguistic fact’ forms an analytic principle.
Diversity in receptor‐like kinase genes is a major determinant of quantitative resistance to Fusarium oxysporum f.sp. matthioli
Authors: Cole Stephanie J. , Diener Andrew C.
Published: June 2013

Resistance to wilt fungus Fusarium oxysporum f.sp. matthioli (FOM) is a polygenic trait in Arabidopsis thaliana. RFO3 is one of six quantitative trait loci accounting for the complete resistance of accession Columbia‐0 (Col‐0) and susceptibility of accession Taynuilt‐0 (Ty‐0).

We find that Col‐0 and Ty‐0 alleles of RFO3 are representative of two common variants in wild Arabidopsis accessions, that resistance and susceptibility to FOM are ancestral features of the two variants and that resistance from RFO3 is unrivalled by other genes in a genome‐wide survey of diversity in accessions. A single receptor‐like kinase (RLK) gene in Col‐0 is responsible for the resistance of RFO3, although the susceptible Ty‐0 allele codes for two RLK homologs.

Expression of RFO3 is highest in vascular tissue, which F. oxysporum infects, and root‐expressed RFO3 restricts FOM infection of the vascular system. RFO3 confers specific resistance to FOM and provides no resistance to two other crucifer‐infecting F. oxysporum pathogens.

RFO3's identity, expression and specificity suggest that RFO3 represents diversity in pattern‐recognition receptor (PRR) genes. The characteristics of RFO3 and the previously published RFO1 suggest that diversity in RLK PRRs is a major determinant of quantitative resistance in wild plant populations.
Do Euro Area Countries Respond Asymmetrically to the Common Monetary Policy?
Authors: Barigozzi Matteo , Conti Antonio M. , Luciani Matteo
Published: June 2013

We investigate the possible existence of asymmetries among Euro Area countries reactions to the European Central Bank monetary policy. Our analysis is based on a Structural Dynamic Factor model estimated on a large panel of Euro Area quarterly variables. Although the introduction of the euro has changed the monetary transmission mechanism in the individual countries towards a more homogeneous response, we find that differences still remain between North and South Europe in terms of prices and unemployment. These results are the consequence of country‐specific structures, rather than of European Central Bank policies.
Gastric pneumatosis and rupture caused by lactobezoar
Authors: Bos Marthel E. , Wijnen Rene M. H. , de Blaauw Ivo
Published: June 2013

Background

Lactobezoar is a compact mass of inspissated, undigested milk. Most often it is located in the stomach but it may also be located in other parts of the intestine. It is the most common type of bezoar in infancy. Reported herein are two cases of this rare condition mimicking necrotizing enterocolitis.

Method

Data on two complicated cases of lactobezoar were retrospective analyzed.

Results

The first case involved a female infant, born at 37 weeks 2 days gestation with a birthweight of 3050 g, and multiple antenatal known congenital defects. Due to esophageal atresia she was given a gastrostomy on the second day of life. After 20 days of continuous feeding with formula feeding she developed food intolerance and clinical signs of a severe sepsis. On examination the abdomen was severely distended and tender at palpation. No palpable mass was noted at examination. Signs of hemodynamic instability and sepsis evolved. Plain abdominal X‐ray showed a pneumatosis of the stomach matching necrotizing enterocolitis (NEC). During emergency laparotomy a gastric bezoar was seen and removed. The postoperative course was complicated by prolonged motility disturbance of the stomach. For a long time she was fed through a jejunostomy. The second case involved a female infant born at 26 weeks 4 days (birthweight 1040 g) who became progressively septic on the day 6 of life. On examination she had a tender and distended abdomen, and abdominal X‐ray showed intra‐abdominal air, consistent with a gastrointestinal perforation. On emergency laparotomy a perforation was seen at the back of the stomach, due to a lactobezoar, with only a little necrosis surrounding it. Surgical treatment consisted of extraction of the lactobezoar and closure of the perforation at the back of the stomach. Two days after the initial surgery, she developed a leakage of the suture anastomosis and another laparotomy was performed. A drain was left near the stomach. After 2 weeks she recovered quickly and feeding was initiated at day 21 with good outcome after 3 months.

Conclusion

Factors associated with the development of lactobezoar are prematurity, low birthweight, disturbed gastric emptying, hypercaloric and hyperosmolaric milk compositions. It is important to realize that lactobezoar formation can occur in preterm and full‐term infants, receiving either breast milk or formula, even when only minimal enteral feeding is given. Early recognition and treatment of this condition is critical. If a lactobezoar is not detected in an early phase, patients can deteriorate very quickly into a condition mimicking NEC.
Suppression of Interferon‐Mediated Antiviral Immunity by Hepatitis B Virus: An Overview of Research Progress
Authors: Guo P.
Published: June 2013

Interferon (IFN)‐α is an indispensable drug for hepatitis B treatment in clinical settings. However, hepatitis B virus (HBV) can attenuate IFN‐mediated antiviral responses to avoid being inhibited or cleared. Much progress has been made in exploring how the IFN‐induced anti‐HBV effect is inhibited. This review examines and summarizes new advances regarding the molecular mechanism underlying the HBV‐induced suppression of type I IFN‐mediated antiviral immunity.
Strongyloides stercoralis infection in an intestinal transplant recipient
Authors: Hsu C.N. , Tseng S.H. , Chang S.W. , Chen Y.
Published: June 2013

Strongyloides stercoralis is a helminth in tropical and subtropical areas. It may cause latent infection and progress to Strongyloides hyperinfection syndrome, which is associated with a high mortality rate. Transplant recipients under the treatment of immunosuppressant agents are at risk of severe S. stercoralis infection. According to related literature, most cases of S. stercoralis infection after solid organ transplantation are caused by reactivation of latent infections in the recipients, whereas only a few are acquired from the donors. We report on an intestinal transplant recipient who had S. stercoralis infection diagnosed by a larva of this parasite found in the stool from the ileostomy stoma 1 month after transplantation. The donor was considered the source of the infection because the donor was from an endemic area and had marked eosinophilia, and the recipient had no contact history or clinical manifestations related to the S. stercoralis infection before transplantation. The patient was treated with ivermectin and exhibited no evidence of infection after 7 months.
Cytomegalovirus infection of the major duodenal papilla in a renal allograft recipient with severe biliary obstruction and acalculous cholecystitis
Authors: Riediger C. , Beimler J. , Weitz J. , Zeier M. , Sauer P.
Published: June 2013

Cytomegalovirus (CMV) can cause severe infections with serious consequences in renal transplant recipients. Disseminated CMV infections can affect almost every organ, but obstructive cholestasis and cholangitis, as a consequence of a CMV‐induced papillitis, is extremely rare. We are reporting a rare case of obstructive cholestasis and cholecystitis due to CMV‐related inflammation of the major duodenal papilla in a 60‐year‐old woman 3 months after renal transplantation. In addition, the patient suffered from a disseminated CMV infection with ulcerative esophagitis and gastritis. Because of the severe CMV infection, failure of the renal graft occurred. Obstructive cholestasis was resolved through internal stenting, and the progressive cholecystitis necessitated an emergency cholecystectomy. Following antiviral therapy with ganciclovir, the gastrointestinal ulcerations regressed and renal function was restored. Diagnosis of the CMV‐related disease was established only in tissue samples, whereas standard serologic tests had failed.
Fractal Analysis Illuminates the Form of Connectionist Structural Gradualness
Authors: Tabor Whitney , Cho Pyeong Whan , Szkudlarek Emily
Published: June 2013

We examine two connectionist networks—a fractal learning neural network (FLNN) and a Simple Recurrent Network (SRN)—that are trained to process center‐embedded symbol sequences. Previous work provides evidence that connectionist networks trained on infinite‐state languages tend to form fractal encodings. Most such work focuses on simple counting recursion cases (e.g., ), which are not comparable to the complex recursive patterns seen in natural language syntax. Here, we consider exponential state growth cases (including mirror recursion), describe a new training scheme that seems to facilitate learning, and note that the connectionist learning of these cases has a continuous metamorphosis property that looks very different from what is achievable with symbolic encodings. We identify a property—ragged progressive generalization—which helps make this difference clearer. We suggest two conclusions. First, the fractal analysis of these more complex learning cases reveals the possibility of comparing connectionist networks and symbolic models of grammatical structure in a principled way—this helps remove the black box character of connectionist networks and indicates how the theory they support is different from symbolic approaches. Second, the findings indicate the value of future, linked mathematical and empirical work on these models—something that is more possible now than it was 10 years ago.
Export Credit Guarantees and Export Performance: Evidence from Austrian Firm‐level Data
Authors: Badinger Harald , Url Thomas
Published: June 2013

This paper provides an economic assessment of export credit guarantee commitments by the Austrian export credit agency, using firm‐level data on a cross‐section of Austrian exporting firms for the year 2008. In a first step, we explore various determinants of export guarantee usage. Results suggest that firm size, being part of a multinational enterprise, exposure to revenue risk and R&D intensity are important factors. In a second step, we investigate the effects of export guarantees on export performance. Identification is achieved using as instruments the exogenous determinants of export guarantee usage identified in the first step. We find that there are economically and statistically significant effects of export credit guarantee usage on firm‐specific export performance ranging from some 80 to 100 per cent compared with the control group of non‐users.
Financial Crisis and Productivity Evolution: Evidence from Indonesia
Authors: Poczter Sharon , Gertler Paul , Rothenberg Alexander D.
Published: June 2013

We examine how the productivity of different industries changes over the course of a financial crisis by exploiting cross‐firm, within‐industry differences in productivity resulting from the Asian financial crisis of 1997. We show that the crisis coincided with dramatic changes in productivity and that many of these changes were sustained in the long run. In particular, an increasing number of industries experienced decreases in average firm productivity during the crisis and did not recover. Further, we find that changes in industrial productivity in the recovery period are driven not by increases in the productivity of existing firms, but rather by the entry of new firms and changes to the reallocation of market share. Finally, we find that foreign exporters' productivity was the least impacted by the crisis, suggesting that only access to alternate forms of both capital and international markets can help to smooth investment and maintain productivity over a financial crisis.
Intraregional Spillovers in South America: Is Brazil Systemic After All?
Authors: Adler Gustavo , Sosa Sebastián
Published: June 2013

The high business cycle correlation between Brazil (the large neighbour in South America) and other countries in the region has been a frequent source of concern for policymakers, as it has been viewed as evidence of the large influence of the former country on its neighbours. This paper studies the importance of such influence, documenting trade linkages over the last two decades and quantifying spillover effects in a vector autoregression setting. We find that, after controlling for common external factors, spillovers from Brazil are only relevant for Southern Cone economies (especially Mercosur's members) and Peru, but not for the rest of South America, and these findings are consistent with the extent of trade linkages between these countries. We find also that spillovers can take two different forms: the transmission of Brazil‐specific shocks and the amplification of global shocks – through their impact on Brazil's output. Finally, we also find suggestive evidence that depreciations of Brazil's currency may not have significant impact on output of its key trading partners.
Use of Evidence in Clinical Guidelines and Everyday Practice for Mechanical Ventilation in Swedish Intensive Care Units
Authors: Eldh Ann Catrine , Vogel Gisela , Söderberg Anna , Blomqvist Hans , Wengström Yvonne
Published: June 2013

Background and Aim

One way to support evidence‐based decisions in health care is by clinical guidelines, in particular, in highly specialized care such as intensive care units (ICUs). The aim of this study was to explore the development and dissemination of guidelines regarding mechanical ventilation (MV) in Swedish ICUs, and the use of evidence on MV in guidelines and everyday practice.

Methods

Inviting all general ICUs in Sweden (N = 65), a national survey was performed on occurrence of MV guidelines, and a review of submitted ICU guidelines by four evidence items from the AGREE instrument. In addition, ICU head nurses and senior physicians were interviewed using semistructured and open‐ended questions to explore development and dissemination of MV guidelines, staff adherence or nonadherence to guidelines, and everyday practice of MV management bedside.

Findings

Fifty‐five ICUs (85%) participated in the study; 51 ICUs submitted a total of 245 guidelines, including recommendations for medical or nursing MV actions. None of the documents included how evidence had been sought or assessed, while 22% included a list of references (n = 54). No guidelines included patients’ experiences of MV. According to the managers, the guidelines were most often compiled by a multiprofessional team sharing the information through the ICU's website. The guidelines were mainly used as a basis for MV management bedside, but variation occurred as a result of personal preferences, lack of awareness, and adjustment to patients’ needs.

Conclusions

Local MV guidelines seem to constitute a basis for healthcare practice in Swedish ICUs, even though the evidence proposed was limited with respect to how it was attained and lacked patient perspectives. In addition, the strategies used for dissemination were limited, suggesting that further initiatives are needed to support knowledge translation in advanced healthcare environments such as ICUs.
Turning Knowledge Into Action at the Point‐of‐Care: The Collective Experience of Nurses Facilitating the Implementation of Evidence‐Based Practice
Authors: Dogherty Elizabeth J. , Harrison Margaret B. , Graham Ian D. , Vandyk Amanda Digel , Keeping‐Burke Lisa
Published: June 2013

Background

Facilitation is considered a way of enabling clinicians to implement evidence into practice by problem solving and providing support. Practice development is a well‐established movement in the United Kingdom that incorporates the use of facilitators, but in Canada, the role is more obtuse. Few investigations have observed the process of facilitation as described by individuals experienced in guideline implementation in North America.

Aim

To describe the tacit knowledge regarding facilitation embedded in the experiences of nurses implementing evidence into practice.

Methods

Twenty nurses from across Canada were purposively selected to attend an interactive knowledge translation symposium to examine what has worked and what has not in implementing evidence in practice. This study is an additional in‐depth analysis of data collected at the symposium that focuses on facilitation as an intervention to enhance evidence uptake. Critical incident technique was used to elicit examples to examine the nurses’ facilitation experiences. Participants shared their experiences with one another and completed initial data analysis and coding collaboratively. The data were further thematically analyzed using the qualitative inductive approach of constant comparison.

Results

A number of factors emerged at various levels associated with the successes and failures of participants’ efforts to facilitate evidence‐based practice. Successful implementation related to: (a) focus on a priority issue, (b) relevant evidence, (c) development of strategic partnerships, (d) the use of multiple strategies to effect change, and (e) facilitator characteristics and approach. Negative factors influencing the process were: (a) poor engagement or ownership, (b) resource deficits, (c) conflict, (d) contextual issues, and (e) lack of evaluation and sustainability.

Conclusions

Factors at the individual, environmental, organizational, and cultural level influence facilitation of evidence‐based practice in real situations at the point‐of‐care. With a greater understanding of factors contributing to successful or unsuccessful facilitation, future research should focus on analyzing facilitation interventions tailored to address barriers and enhance facilitators of evidence uptake.
An Experimental Study of Loss Sources in a Fan Operating With Continuous Inlet Stagnation Pressure Distortion
Authors: Gunn Ewan J. , Tooze Sarah E. , Hall Cesare A. , Colin Yann
Published: June 2013

The viability of boundary layer ingesting (BLI) engines for future aircraft propulsion is dependent on the ability to design robust, efficient engine fan systems for operation with continuously distorted inlet flow. A key step in this process is to develop an understanding of the specific mechanisms by which an inlet distortion affects the performance of a fan stage. In this paper, detailed full-annulus experimental measurements of the flow field within a low-speed fan stage operating with a continuous 60 deg inlet stagnation pressure distortion are presented. These results are used to describe the three-dimensional fluid mechanics governing the interaction between the fan and the distortion and to make a quantitative assessment of the impact on loss generation within the fan. A 5.3 percentage point reduction in stage total-to-total efficiency is observed as a result of the inlet distortion. The reduction in performance is shown to be dominated by increased loss generation in the rotor due to off-design incidence values at its leading edge, an effect that occurs throughout the annulus despite the localized nature of the inlet distortion. Increased loss in the stator row is also observed due to flow separations that are shown to be caused by whirl angle distortion at rotor exit. By addressing these losses, it should be possible to achieve improved efficiency in BLI fan systems.
Performance Analysis of an Integrated Micro Cryogenic Cooler and Miniature Compressor for Cooling to 200 K
Authors: Lewis Ryan , Lin M.-H. , Wang Yunda , Cooper Jill , Bradley Peter , Radebaugh Ray , Huber Marcia , Lee Y. C.
Published: June 2013

Joule-Thomson (J-T) based micro cryogenic coolers (MCCs) are attractive because they can provide the cryogenic temperatures needed for small electronic devices while having a low cost and small volumetric footprint. A compressor is a major part of a cryogenic system, but so far J-T based MCCs have not used miniature or microscale compressors. This work demonstrates a J-T based MCC coupled with a miniature compressor for cooling to 200 K, with precooling of 273 K, using a custom hydrocarbon mixture as refrigerant. The compressor is formed by coupling a miniature piston oscillator built for stirling coolers with a micromachined check valve assembly. The MCC is formed by glass fibers within a capillary forming a counter flow heat exchanger, and a silicon and glass chip forming a J-T valve. Minimum temperatures of 166 K have been observed in transient, and stable temperatures of 200 ±1 K have been observed for >1 h. Some insight is given into the unstable performance in terms of intermittent liquid accumulation. The coefficient of performance is analyzed for the system, and it is found that most of the inefficiencies arise at the compressor.
Evaporative Annular Flow in Micro/Minichannels: A Simple Heat Transfer Model
Authors: Wu Zan , Sundén Bengt , Li Wei , Wadekar Vishwas V.
Published: June 2013

The present study collected and analyzed flow boiling data points which fall in the annular flow regime with an increasing heat transfer coefficient h - vapor quality x trend (h increases with increasing x) in small diameter channels (0.1 < dh < 3.1 mm) for halogenated refrigerants, CO2 and water. In this annular flow regime, heat transfer coefficient also depends on both heat flux and mass flux. It is proposed that the heat flux dependence comes mainly through its effect on interfacial waves and the fact that bubble growth and coalescence in isolated bubble flow and elongated bubble flow propagate oscillations downwards into the annular flow. In other words, heat flux affects the heat transfer coefficient in the annular flow regime by upstream effects or historical effects. A semi-empirical model for annular flow was developed by starting with pure thin film evaporation and then corrections were applied based on the Boiling number and the liquid Reynolds number. The resulting simple model can predict about 89.1% of the entire database within a ± 30% error band. Almost all data points can be predicted within a ± 50% error band. It is shown that the parametric trends are well captured by the new model. Besides, no noticeable macro-to-micro/miniscale transition was observed for the entire database of annular flow. Therefore, the new model can be applied to model annular flow covering from microchannels to relatively large channels.
Evaluating Thermal Performance and Energy Conservation Potential of Hybrid Earth Air Tunnel Heat Exchanger in Hot and Dry Climate—In Situ Measurement
Authors: Misra Rohit , Bansal Vikas , Das Agarwal Ghanshyam , Mathur Jyotirmay , Aseri Tarun
Published: June 2013

Earth air tunnel heat exchanger is a passive cooling device with advantageous feature to reduce energy consumption in buildings. Curtailing the electricity consumption of conventional vapor compression system based air-conditioner is a major concern especially in area with hot and dry weather conditions. The performance of conventional air-conditioners can substantially be enhanced by coupling these active cooling systems with passive cooling systems. In the present research, the thermal performance and energy conservation potential of hybrid cooling system has been investigated experimentally. An attempt has been made to enhance the thermal performance of active cooling system by coupling it with earth air tunnel heat exchanger (EATHE) in two different hybrid modes. The air which comes out of EATHE is relatively cooler than the ambient air and therefore can be used either for cooling the condenser tubes of a conventional window type air-conditioner or supplying it directly to the room being conditioned. The energy consumption of conventional 1.5TR window type air conditioner is found to be reduced by 16.11% when cold air from EATHE is completely used for condenser cooling.
Energy Streamlines Analyses on Natural Convection Within Porous Square Enclosure With Internal Obstructions
Authors: Humaira Tasnim Syeda , Mahmud Shohel , Dutta Animesh
Published: June 2013

Natural convection through a porous layer heated from the side with internal flow obstructions have been investigated based on visualization of total energy flow via energy streamfunctions or energy streamlines. Energy streamline has been introduced previously by Mahmud and Fraser (2007, “Visualizing Energy Flows Through Energy Streamlines and Pathlines,” Int. J. Heat Mass Transfer, 50, pp. 3990–4002) as an alternate convection heat transfer energy visualization technique. Energy streamlines consider all forms of related energy; for example, thermal energy, potential energy, kinetic energy, electrical energy, magnetic energy, and chemical energy. A finite volume method has been employed to solve momentum and energy balance as well as postprocessing energy streamfunctions. A parametric study has been carried out using the following parameters: Rayleigh number (Ra) from 103 to 106, Darcy number (Da) from 10−4 to 10−3, dimensionless thin fin lengths (L) 0.25, 0.5, and 0.75, dimensionless positions (H) 0.25, 0.5, and 0.75 with Prandtl number (Pr) 0.7. One finding of the present study is that, adding an obstruction in a cavity is similar to reducing Da of the porous medium. Therefore, the average Nusselt number calculated on the hot wall of the cavity always degraded compared to the no obstruction case whenever a baffle is attached. Thus the attached horizontal obstruction adds some thermal insulation effect. This finding is important in double wall space filled with fiberglass insulation in contemporary buildings, where the side wall is reinforced on the inside with structural members.
A Dedicated Low-Cost Fluorescence Microfluidic Device Reader for Point-of-Care Ocular Diagnostics
Authors: Pestana Noah , Walsh David , Hatch Adam , Hahn Paul , Jaffe Glenn J. , Murthy Shashi K. , Niedre Mark
Published: June 2013

Microfluidic fluorescence assay devices show great promise as preclinical and clinical diagnostic instruments. Normally, fluorescence signals from microfluidic chips are quantified by analysis of images obtained with a commercial fluorescence microscope. This method is unnecessarily expensive, time consuming, and requires significant operator training, particularly when considering future clinical translation of the technology. In this work, we developed a dedicated low cost fluorescence microfluidic device reader (FMDR) to read sandwich immunofluorescence assay (sIFA) devices configured to detect vascular endothelial growth factor ligand concentrations in ocular fluid samples. Using a series of sIFA calibration standards and a limited set of human ocular fluid samples, we demonstrated that our FMDR reader has similar sensitivity and accuracy to a fluorescence microscope for this task, with significantly lower total cost and reduced reading time. We anticipate that the reader could be used with minor modifications for virtually any fluorescence microfluidic device.
Study on Performance Evaluation of Dispersed Particle Gel for Improved Oil Recovery
Authors: You Qing , Dai Caili , Tang Yongchun , Guan Ping , Zhao Guang , Zhao Fulin
Published: June 2013

This work investigates the performance of dispersed particle gel (DPG) by core flow tests including injectivity, selective plugging, thermal stability, and improved oil recovery (IOR). Results showed that the resistance factor is small when DPG was injected, but obviously became larger while turning into brine water flooding. Both the oil and water relative permeability were reduced and greater reduction appeared in water relative permeability. DPG could block water flow without affecting oil flow, and oil–water segregated flow mechanism was proposed to explain this selective plugging. The injection pressure increases, caused by strong plugging due to the DPG aggregation aging in high temperature, which was consistent with the observation of atomic force microscope (AFM) photos. The DPG could effectively block high permeability zone and produce oil from low permeability zone, which could provide a practical way to enhance hydrocarbon recovery while reducing water production for extremely heterogeneous reservoirs.
Effect of Swirl Number on Combustion Characteristics in a Natural Gas Diffusion Flame
Authors: Yılmaz İlker
Published: June 2013

This paper presents the effect of swirl number on combustion characteristics such as temperature, velocity, gas concentrations in a natural gas diffusion flame. Numerial simulations carried out using the commercial computational fluid dynamics (CFD) code, Fluent by choosing appropriate model parameters. The combustion reaction scheme in the flame region was modeled using eddy dissipation model with one step global reaction scheme. A standard k-ε turbulence model for turbulent closure and P-I radiation model for flame radiation inside the combustor is used in the numerical simulations. In order to investigate the swirling effect on the combustion characteristics, seven different swirl numbers including 0; 0.1; 0.2; 0.3; 0.4; 0.5; and 0.6 are used in the study. Numerical results are validated and compared with the published experimental and simulation results. A good consistency is found between the present results and those published measurement and simulation results in the available literature. The results shown that the combustion characteristics such as the flame temperature, the gas concentrations including CO2, H2O, O2, and CH4 are strongly affected by the swirl number. Depending on the degree of swirl, the fluid dynamics behavior of natural gas diffusion flame including axial velocity distribution, central recirculation zone (CTRZ) and external recirculation zone (ETRZ) were also strongly affected.
Active Outer Ring Cooling of High-Loaded and High-Speed Ball Bearings
Authors: Flouros Michael , Hirschmann Markus , Cottier Francois , Gloeckner Peter , Dullenkopf Klaus
Published: June 2013

Bearings for aero engine applications are subjected to a high thermal impact because of the elevated speeds and loads. The high rate of heat generation in the bearing cannot be sustained by the materials used and, in the absence of lubrication, will fail within seconds. For this reason, aero engine bearings have to be lubricated and cooled by a continuous oil stream. The heat that is generated in the bearings through friction is transferred into the oil. Oil itself has limited capabilities and can only remove heat as long as its temperature does not reach critical limits. When the critical limits have been reached or even exceeded, the oil will suffer chemical decomposition (coking) with loss of its properties and subsequently cause a detrimental impact on the rotating machinery. Oil is normally transferred into the bearings through holes in the inner ring, thus taking advantage of the centrifugal forces due to the rotation. On its way through the bearing, the oil continuously removes heat from the inner ring, the rolling elements, and the bearing cage until it reaches the outer ring. Since the oil has already been heated up, its capability to remove heat from the outer ring is considerably reduced. The idea to provide the bearing with an “unlimited” quantity of oil to ensure proper cooling cannot be considered, since an increase in the oil quantity leads to higher parasitic losses (churning) in the bearing chamber and increased requirements on the engine's lubrication system in terms of storage, scavenging, cooling, weight, etc., not mentioning the power needed to accomplish all these. In this sense, the authors have developed a method that would enable active cooling of the outer ring. Similar to fins, which are used for cooling electronic devices, a spiral groove engraved in the outer ring material would function as a fin body with oil instead of air as the cooling medium. The number of “threads” and the size of the groove design characteristics were optimized in a way that enhanced heat transfer is achieved without excessive pressure losses. An experimental setup was created for this reason, and a 167.5-mm pitch circle diameter (PCD) ball bearing was investigated. The bearing was tested with and without the outer ring cooling. A reduction of 50% of the lubricant flow through the inner ring associated with a 30% decrease in heat generation was achieved.
Ejector Scavenging of Bearing Chambers. A Numerical and Experimental Investigation
Authors: Flouros Michael , Cottier Francois , Hirschmann Markus , Kutz Joachim , Jocher Agnes
Published: June 2013

Oil system architecture in aero engines has remained almost the same for the last 30 years. At least one oil feed pump is responsible for distributing pressurized oil into the bearing chambers, and several scavenge pumps are responsible for evacuating the bearing chambers from the oil and the air mixture. Air is used as the sealing medium in bearing chambers and is the dominant medium in terms of volume occupation and expansion phenomena. In order to simplify the oil system architecture and thus improve the system's reliability with less mechanical parts and also decrease weight, an ejector system has been designed for scavenging bearing chambers. The idea behind the ejector is to use high-pressure oil from the feed pump and use it for feeding the ejector's primary jet. Through the momentum transfer between the pressurized oil at the jet's tip and the two-phase mixture of air and oil from the bearing chamber, the mixture will be discharged into the oil tank. In order to design the ejector for aero engine applications, engine-relevant performance conditions had to be considered. The design was performed using a one-dimensional analysis tool and then considerably refined by using the numerical tool ansys cfx. In a further step, the ejector was manufactured out of pure quartz glass and was tested in a lube rig with a bearing chamber, which has evolved from a real engine application. In the bearing chamber, engine-relevant performance conditions were simulated. Through the provided instrumentation for pressures, temperatures, and air/oil flows, the performance characteristics of the ejector were assessed and were compared to the analytic and numerical results. A high-speed camera was used to record the two-phase flow downstream of the bearing chamber in the scavenge pipe. This work is part of the European Union-funded research program Engine LUBrication System TechnologieS (ELUBSYS) within the 7th EU Frame Programme for Aeronautics and Transport (AAT.2008.4.2.3).
Compressible Fluid Model for Hydrodynamic Lubrication Cavitation
Authors: Bayada G. , Chupin L.
Published: June 2013

In this paper, it is shown how vaporous cavitation in lubricant films can be modeled in a physically justified manner through the constitutive (compressibility) relation of the fluid. The method treats the flow as a homogeneous mixture employing a “void fraction” variable to quantify the intensity of cavitation. It has been already proposed to study cavitation in fluid mechanics. It is shown how the widely used Jakobsson–Floberg–Olsson (JFO) / Elrod–Adams (EA) mass flow conservation model can be compared with this new model. Moreover, the new model can incorporate the variation of the viscosity in the cavitation region and allows the pressure to fall below a cavitation pressure. Numerical computations show that discrepancy with JFO/EA is mostly associated with light loading condition, starved situation or viscosity effects.
Comparison Between a Meshless Method and the Finite Difference Method for Solving the Reynolds Equation in Finite Bearings
Authors: Nicoletti Rodrigo
Published: June 2013

Meshless methods are an alternative procedure for solving partial differential equations in opposition to the numerical methods that require structured meshes. In this work, the meshless method with radial basis functions (MMRB) is compared to the finite difference method (FDM) for solving the Reynolds equation applied to lubricated finite bearing applications. The performance of these two methods is compared based on the precision of estimating the normal force applied to the sliding surface of the bearing. Different mesh families are tested for different bearing configurations. Results show that the MMRB is better than the FDM for nonrectangular geometries with coarser meshes. For rectangular domains without discontinuities, the FDM is still the best choice for solving the problem.
Whirl and Friction Characteristics of High Speed Floating Ring and Ball Bearing Turbochargers
Authors: Brouwer Matthew D. , Sadeghi Farshid , Lancaster Craig , Archer Jamie , Donaldson James
Published: June 2013

The objective of this experimental investigation was to design and develop a high speed turbocharger test rig (TTR) in order to critically examine the whirl and frictional characteristics of floating ring and ball bearing turbochargers. In order to achieve the objective, a high speed TTR was designed and developed with the capability of reaching speeds in excess of 100,000 rpm and was equipped with speed and displacement sensors to obtain the necessary results for comparison between the two turbocharger models. The TTR was used to compare and contrast the whirl and friction characteristics of two identical turbochargers differing only by the support structure of the rotor system: one containing a floating ring bearing turbocharger (FRBT) and the other a ball bearing turbocharger (BBT). The TTR is driven by an industrial compressor powered by a six cylinder 14 liter diesel engine. This configuration closely resembles turbocharger operation with an actual engine and was able to operate in both nominal and extreme operating conditions. A pair of displacement sensors was installed to measure the whirl of the rotor near the end of the compressor. Whirl results indicated that the BBT was significantly more rigid and stable than the FRBT. Waterfall plots were used to compare the frequency response of the two turbochargers over the full range of operating speeds. The majority of motion for the BBT was the whirl of the synchronous excitation due to a negligible inherent imbalance with some larger motions caused by vibrational modes. The whirl of the FRBT consists of not only the synchronous motion but also subsynchronous motions as a result of oil film instabilities throughout the entire operating range of speeds. The TTR was also used to compare frictional losses within the bearings. A study of the run-down times after the pressurized air supply was removed indicated that the BBT has significantly lower frictional losses under all operating conditions tested.
Thorough Observation of Real Contact Area of Copper Gaskets Using a Laser Microscope With a Wide Field of View
Authors: Nitta Isami , Matsuzaki Yoshio , Tsukiyama Yosuke , Horita Motoshi , Sakamoto Shuichi
Published: June 2013

To quantitatively predict the leakage rates of static metal seals, it is important to observe the real contact area at seal surfaces because the leakage path consists of the noncontact portions between the flange and gasket surfaces. In a previous study, we observed the real contact situation using a thin polymer film 1 μm in thickness. In the present study, we observed the real contact area on gasket surfaces using a laser microscope with a wide field of view. With this method, observation time over the whole gasket surface could be greatly reduced compared with conventional methods. The observations indicated that the leakage paths on the gasket surfaces were in the radial direction perpendicular to a lathe-turned groove and the circumferential direction along the groove. As the closing loads increased, the leakage paths in the radial direction disappeared and only the leakage path in the circumferential direction remained. When the closing loads increased further, the widths of the leakage paths at both the inside and outside on the gasket surface became narrower. The critical contact pressure where the leakage paths in the radial direction disappear was determined from the observation of the contact surface of the gasket. The leakage rates obtained from the experiments showed good agreement with the calculated values under the assumption of laminar flow along the turned groove over the critical contact pressure.
Automatic reconstruction of the arterial and venous trees on volumetric chest CT
Authors: Park Seyoun , Min Lee Sang , Kim Namkug , Beom Seo Joon , Shin Hayong
Published: June 2013

Purpose:

This paper introduces a novel approach to classify pulmonary arteries and veins from volumetric chest computed tomography (CT) images. Although there is known to be a relationship between the alteration of vessel distributions and the progress of various pulmonary diseases, there has been relatively little research on the quantification of pulmonary vesselsin vivo due to morphological difficulties. In particular, there have been few efforts to quantify the morphology and distribution of only arteries or veins through automated algorithms despite the clinical importance of such work. In this study, the authors classify different types of vessels by constructing a tree structure from vascular points while minimizing the construction cost using the vascular geometries and features of CT images.

Methods:

First, a vascular point set is extracted from an input volume and the weights of the points are calculated using the intensity, distance from the boundaries, and the Laplacian of the distance field. The tree construction cost is then defined as the summation of edge connection costs depending on the vertex weights. As a solution, the authors can obtain a minimum spanning tree whose branches correspond to different vessels. By cutting the edges in the mediastinal region, branches can be separated. From the root points of each branch, the cut region is regrouped toward the entries of pulmonary vessels in the same framework of the initial tree construction. After merging branches with the same orientation as much as possible, it can be determined manually whether a given vessel is an artery or vein. Our approach can handle with noncontrast CT images as well as vascular contrast enhanced images.

Results:

For the validation, mathematical virtual phantoms and ten chronic obstructive pulmonary disease (COPD) noncontrast volumetric chest CT scans with submillimeter thickness were used. Based on experimental findings, the suggested approach shows 9.18 ± 0.33 (mean ± SD) visual scores for ten datasets, 91% and 98% quantitative accuracies for two cases, a result which is clinically acceptable in terms of classification capability.

Conclusions:

This automatic classification approach with minimal user interactions may be useful in assessing many pulmonary disease, such as pulmonary hypertension, interstitial lung disease and COPD.
Particle–antiparticle potential in scalar quantum field theory with a Higgs-like mediating field
Authors: Chigodaev Alexander , Darewych Jurij W.
Published: June 2013

We study the particle–antiparticle force in a model scalar quantum field theory (QFT) with a nonlinear Higgs-like mediating field. We use the variational method in a reformulated Hamiltonian formalism of the theory. The trial state consists of a superposition of single-pair and two-pair Fock states. Coupled relativistic integral equations for the one- and two-pair channel functions are derived and their nonrelativistic limit forms are obtained. Variational ansatz are used to derive the correction to the dominant Yukawa interparticle potential for the particle–antiparticle system. The correction is found to be an attractive short-range potential.
STU–QCD correspondence
Authors: Pourhassan B. , Sadeghi J.
Published: June 2013

In this review article we consider a special case of D = 5, [Formula: see text] supergravity called the STU model. We apply the gauge–gravity correspondence to the STU model to gain insight into properties of the quark–gluon plasma. Given that the quark–gluon plasma is in reality described by quantum chromodynamics (QCD), we call our study STU–QCD correspondence. First, we investigate the thermodynamics and hydrodynamics of the STU background. Then we use a dual picture of the theory, which is type IIB string theory, to obtain the drag force and jet-quenching parameter of an external probe quark.
A FRAMEWORK FOR VIDEO SEGMENTATION USING GLOBAL AND LOCAL FEATURES
Authors: BABER JUNAID , AFZULPURKAR NITIN , SATOH SHIN'ICHI
Published: June 2013

Rapid increase in video databases has forced the industry to have efficient and effective frameworks for video retrieval and indexing. Video segmentation into scenes is widely used for video summarization, partitioning, indexing and retrieval. In this paper, we propose a framework for scene detection mainly based on entropy and Speeded Up Robust Features (SURF) features. First, we detect the fade and abrupt boundaries based on frame entropy analysis and SURF features matching. Fade boundaries are smart indication of scenes beginning or ending in many videos and dramas, and are detected by frame entropy analysis. Before abrupt boundary detection, unnecessary frames which are obviously not abrupt boundaries, such as blank screens, high intensity influenced images, sliding credits, are removed. Candidate boundaries are detected to make SURF features efficient for abrupt boundary detection, and SURF features between candidate boundaries and their adjacent frames are used to detect the abrupt boundaries. Second, key frames are extracted from abrupt shots. We evaluate our key frame extraction with other famous algorithms and show the effectiveness of the key frames. Finally, scene boundaries are detected using sliding window of size K over the key frames in temporal order. In experimental evaluation on the TRECVID-2007 shot boundary test set, the algorithm for shot boundary achieves substantial improvements over state-of-the-art methods with the precision of 99% and the recall of 97.8%. Experimental results for video segmentation into scenes are also promising, compared to famous state-of-the-art techniques.
X-RAY PHOTOELECTRON SPECTROSCOPY AND SCANNING ELECTROCHEMICAL MICROSCOPY STUDIES OF BRANCHED MULTIWALLED CARBON NANOTUBE PAPER MODIFIED BY ELECTROCHEMICAL GRAFTING AND CLICK CHEMISTRY
Authors: COATES MEGAN , NYOKONG TEBELLO
Published: June 2013

Modification of nanomaterials through electrochemical grafting is a useful approach to introduce linking groups on to the surface of these structures. This work shows the possibility of applying electrochemical grafting to branched multiwalled carbon nanotube paper with an electrical resistance of 0.1 ohm-cm, and subsequent reaction of the grafted 4-azidobenzenediazonium with ethynylferrocene through the Sharpless click chemistry reaction. A comparison is made between this paper electrode and adsorbed single-walled carbon nanotubes on a glassy carbon electrode, with electrochemistry, X-ray photoelectron spectroscopy and scanning electrochemical microscopy used for characterization.