bluuebunny/crossref_metadata_2025 huggingface dataset:
Rater types in writing performance assessments: A classification approach to rater variability
Authors: Eckes Thomas
Published: March 2008

Research on rater effects in language performance assessments has provided ample evidence for a considerable degree of variability among raters. Building on this research, I advance the hypothesis that experienced raters fall into types or classes that are clearly distinguishable from one another with respect to the importance they attach to scoring criteria. To examine the rater type hypothesis, I asked 64 raters actively involved in scoring examinee writing performance on a large-scale assessment instrument to indicate on a four-point scale how much importance they would attach to each of nine routinely used criteria. The criteria covered various performance aspects, such as fluency, completeness, and grammatical correctness. In a preliminary step, many-facet Rasch analysis revealed that raters differed significantly in their views on the importance of the various criteria. A two-mode clustering technique yielded a joint classification of raters and criteria, with six rater types emerging from the analysis. Each of these types was characterized by a distinct scoring profile, indicating that raters were far from dividing their attention evenly among the set of criteria. Moreover, rater background variables were shown to partially account for the scoring profile differences. The findings have implications for assessing the quality of large-scale rater-mediated language testing, rater monitoring, and rater training.
The assessment of deep word knowledge in young first and second language learners
Authors: Schoonen Rob , Verhallen Marianne
Published: March 2008

The assessment of so-called depth of word knowledge has been the focus of research for some years now. In this article the construct of deep word knowledge is further specified as the decontextualized knowledge of word meanings and word associations. Most studies so far have involved adolescent and adult second language learners. In this article, we extend the focus to younger first and second language learning children in primary school in the Netherlands. A well-established test format involving word associations has been adapted for this younger target group and the feasibility of assessing deep word knowledge in primary school children is evaluated empirically. The results showed that the test provides a reliable and efficient method of assessing the children's vocabulary knowledge. Evidence of validity was obtained from a concurrent definition task, and from an analysis of the scores in terms of language background, which is known to be associated with different levels of vocabulary knowledge.
Construct validation of Bachman and Palmer's (1996) strategic competence model over time in EFL reading tests
Authors: Phakiti Aek
Published: March 2008

This article reports on a large-scale study that aims to validate the theory of strategic competence proposed by Bachman and Palmer (1996) through the use of structural equation modeling (SEM). The present study examines the relationship of test-takers' long-term strategic knowledge (i.e., trait strategies) and actual strategy use (i.e., state strategies) to second language (L2) reading test performance over time. The data were gathered on two occasions (during the mid-term and final examination periods). Five hundred and sixty-one Thai university test-takers answered a trait strategy use questionnaire prior to the mid-term and final reading achievement tests and, immediately after completing each test, they answered a state strategy use questionnaire. It was found that (1) trait metacognitive strategy use (MSU) directly and strongly affects trait cognitive strategy use (CSU); (2) trait CSU does not greatly affect state CSU; (3) trait MSU directly affects state MSU in a specific context, which in turn directly affects state CSU; and (4) state CSU directly affects a specific language test performance to a varying degree.
Rural Hotspots
Authors: McCleary Richard
Published: March 2008

A recent U.S. Tenth Circuit decision questions whether the routine activity theory of hotspots applies to adult businesses located in sparsely populated rural areas. Although few criminologists are interested in urban—rural differences, the Tenth Circuit decision makes this topic acutely relevant to policy makers and courts. To address the threshold question, the hotspot theory is analyzed to demonstrate its generality to urban, suburban, and rural locations. The results of a corroborating case study are then presented. When an adult entertainment business opens on an interstate highway off-ramp to a small rural village, total crime rises by 60%. Alternative explanations related to uncontrolled threats to internal validity are considered and ruled out. After reporting the results of the case study, the consequences of the theory and results for policy makers and courts are discussed.
Uncertainty, Difficulty, and Complexity
Authors: Page Scott E.
Published: March 2008

In this article I clarify the often muddled distinctions between uncertainty, difficulty, and complexity and show that all three can enhance our understanding of institutional performance and design. To cope with uncertainty, institutions align incentives for information revelation; to handle difficult problems, institutions create incentives for diverse problem-solving approaches; and to harness complexity, institutions adjust selection criteria, rates of variation, and the level of connectedness. The distinction between complex systems and equilibrium systems also necessitates a discussion of the differences between the existence, stability, and attainment of equilibria and why, despite often being neglected, the latter two concepts are important to our understanding of institutions.
Getting a Poor Return
Authors: Howard Robert M.
Published: March 2008

Many years ago Robert Dahl (1957) argued that the courts are rarely out of alignment with the dominant national political coalition and more recent scholarship has built on this argument. However, despite this, it is still a prevalent belief that courts protect the minority against the power of the majority. This article analyzes these views by examining the influence of the national coalition and courts on tax policy. The article shows that from 1994 through 2000 a shift to more low-income audits results from political and judicial influence on the agency. The dominant national political coalition, the Tax Court, and to a lesser extent the District Courts, are major players in setting and determining agency policy. This confirms what Dahl noted years ago, namely that the courts are rarely out of alignment with the dominant national political coalition, and actually enforce the policy preferences of the dominant political coalition.
Navigating the Legislative Divide
Authors: Beckmann Matthew N. , McGann Anthony J.
Published: March 2008

Polarization hallmarks contemporary Washington's political landscape. While an increasing literature examines the factors propelling this schism, theoretical work investigating its consequences has just begun. Building from a simple bargaining model in which an exogenous actor (e.g. the president) strategically allocates scarce `political capital' to induce changes in legislators' preferences, we examine how varying the chamber's preference distribution affects the policies that result. Instead of miring presidents' preferred policies in gridlock, the model shows that ideological polarization — in the form of a bimodal distribution — can actually enable a president to pass policies closer to his ideal than would have been possible under greater ideological homogeneity.
Integrated Optimization of Material Layout and Control Voltage for Piezoelectric Laminated Plates
Authors: Zhan Kang  , Liyong Tong
Published: March 2008

Topology optimization techniques have recently been successfully applied to the design of piezoelectric smart structures. However, in previous formulations, the material layout is optimized under the condition of given electric actuation voltages. This imposes a restriction to the design problem and may consequently limit application of these approaches, particularly in complex shape control problems. The present article investigates the integrated optimization of structural topology and control voltage of piezoelectric laminated plates. The finite element analysis formulation of laminated plates with surface bonded piezoelectric layers is introduced first. The optimal design problem is then formulated based on an artificial material model with penalization for both mechanical and piezoelectric properties. In the formulated problem, the topologies of both host and actuation layers are optimized simultaneously with spatial distribution of control voltage. Several special cases of the proposed design problem are considered, and numerical techniques for sensitivity analysis and optimal solutions are proposed. Numerical examples are presented to demonstrate the validity and applicability of the proposed methods.
Analytically Evaluating the Properties and Performance of Layered Magnetoelectric Composites
Authors: Chang Chia-Ming , Carman Gregory P.
Published: March 2008

A theoretical model has been developed for predicting the magnetoelectric (M-E) coupling effect of magnetostrictive-piezoelectric layered composites (MPLC). This model determines the individual effects of MPLC configurations and material properties on the homogenized M-E voltage coefficient, α ', curves. By analyzing the model, a 3D α' sequencing map covering the span of compliance, Poisson's ratio, and piezomagnetic coefficient ratio q33/q31 of the magnetostrictive phases is generated to aid the MPLC design. Six MPLC configurations are addressed in this study, including three field orientations, longitudinal, transverse, and in-plane, in both 1D and 2D geometries. Results show that the piezoelectric volume fraction required for achieving the maximum M-E effect is dependent upon the compliance. Higher compliance values cause the α' peaks to be attenuated, as well as shifted to lower piezoelectric volume fractions. This study also investigates the influence of the piezomagnetic coefficient q33 and the ratio q33/q31 on α' . For a constant ratio q33/q31, larger q 33-values increase α'. However, changing this ratio alters the relative ordering of the α'-values for each of the six MPLC configurations studied. This demonstrates that the ratio q33/q 31 strongly influences the selection of the MPLC configurations to produce the largest M-E coupling effect. By integrating the results from this model into 3D α' sequencing map, the ideal MPLC configuration with the highest M-E coupling effect can be predicted for all possible MPLC magnetostrictive phases.
Protecting Professional Composure in Transcultural Pediatric Nursing
Authors: Pergert Pernilla , Ekblad Solvig , Enskär Karin , Björk Olle
Published: March 2008

In this qualitative study, we used grounded theory to explore the category of “overwhelming emotional expressions” that emerged in a previous study. Using theoretical sampling, 12 individual interviews were conducted with nurses in Swedish pediatric care. Overwhelming emotional expressions have been found to override nurses' professional preparedness; they continuously resolve this by protecting professional composure. Various strategies are used to protect professional composure, including rationalizing, controlled expression, power display, escape/avoidance, distancing, sharing, and management of space. Some of these strategies are similar to coping strategies. However, they differ in that they are about managing the situation and also include protecting the professional composure of the individual as well as the whole care situation. Nurses need to gain preparedness to meet overwhelming emotional expressions in transcultural care and to be aware of strategies for protecting professional composure so as to use them consciously and positively.
Explaining Cross-National Differences in Polygyny Intensity
Authors: Barber Nigel
Published: March 2008

Possible adaptive functions of polygyny include resource-defense, scarcity of men, and countering a high pathogen load, and cultural determinists posit religion and gender discrimination as factors. Using a sample of 32 polygynous countries broken down by urban and rural location, each of these explanations of polygyny was tested in regression analysis. Polygyny increased in tropical countries having plenty of arable land and unequal distribution of wealth (Gini coefficient), supporting the resource-defense explanation. Polygyny also increased in female-biased populations and in countries with a high burden of infectious diseases. In contrast, there was little evidence for cultural determination of polygyny (favorable religion, approval of wife beating, exposure to mass media), although female literacy was a negative predictor. Results thus support the three main functional theories (resource-defense, scarcity of men, pathogen defense) and reject cultural determinist accounts of polygyny.
The Roles and Responsibilities of a Foreign Service Health Practitioner: Serving in a Developing Country
Authors: Pieh Clara D. J.
Published: March 2008

Foreign service health practitioners (FSHPs) support the realization of the goals and objectives of U.S. embassies and ensure the health unit's operational capacity, from the treatment of minor emergencies to evacuating a patient for advanced emergency care. Effective planning for emergencies as a result of a terrorist attack, natural disaster, or highly communicable disease is contingent on the level of emergency preparedness. A FSHP is uniquely positioned to focus on critical issues involving the assessment of local health care resources and preparing for medical emergencies. This is especially true for assessing the availability and functionality of local medical resources in a developing country such as Sierra Leone, West Africa. The serious deficiencies in Sierra Leone's health system and its lack of ability to respond to medical emergencies demand the FSHP to integrate special knowledge, skills, and abilities that are essential for managing the overall health care services provided at the embassy's health unit.
The Preadmission Testing Unit: Patient's First Contact With the Health Care System
Authors: Morgan Mary Jo
Published: March 2008

Shorter lengths of stay in the hospital decrease costs and the likelihood of hospital-acquired infections. Preadmission units replace the old practice of hospital admissions the day before surgery. This article describes how the preadmission unit at Maine Medical Center meets the need for getting patients thoroughly prepared for their surgical procedures in an outpatient setting.
Developing a “Train the Trainer” Program to Identify Elder Abuse and Neglect: The Jewish Home Lifecare System Model
Authors: Radensky Laura , Parikh Deepa
Published: March 2008

Numerous elders are victims of abuse and neglect. Although in a better position than most health care staff to observe and report abuse and neglect in the home, many in the home health care services are not adequately equipped to identify the signs of abuse, much less know how to effectively navigate the vast web of available resources. Many staff are unclear regarding how to report and to whom, and often there is fear of the ramifications of reporting. In addition, in many instances the elder does not wish to seek interventions. The Jewish Home and Hospital Lifecare System's Elder Abuse “train the trainer” model focuses on providing in-service training for clinical and nonclinical members of the organization, with the hopes that personnel will improve their ability to take appropriate action when identifying elder abuse and neglect. In addition, the program prepares home care personnel to act as mentors to paraprofessional home health aides.
The Heritage of Cross Cultural Management Research
Authors: Peterson Mark F.
Published: March 2008

Cross cultural research has made a number of contributions to social thought and has a number of limitations that suggest directions for future work. Understanding the current state and potential future of the field requires understanding how the history of culture analysis has shaped what we as scholars do and what our audience hears. That sort of understanding influences the significance of establishing a Hofstede Chair in Cultural Diversity at Maastricht University as well as influencing the purposes for which the chair should be used.
Unity and Diversity in Arab Managerial Styles
Authors: Smith Peter B. , Achoui Mustafa , Harb Charles
Published: March 2008

A key approach to understanding cross-national variations in leadership is to examine how leaders handle routine events within their span of control. The sources of guidance employed by samples of middle and senior managers in four Arab nations were surveyed. Saudi managers showed the expected traditional and personalistic pattern of relatively strong reliance on both formal rules and unwritten rules, as well on as co-workers and subordinates. Respondents from Qatar, Oman and Lebanon each differed from this pattern in ways consistent with theories of modernity. Correlations with evaluations of how specific work events had been handled in each nation confirmed the presence of distinctive leader styles. The assumption that there is a relatively uniform style of leadership across Arab nations is thus questioned.
A Comparison of Leadership Prototypes of Arab and European Females
Authors: Neal Mark , Finlay Jim L. , Catana Gh. Alexandru , Catana Doina
Published: March 2008

What do young, business-educated Arab women think about leadership? This study addresses this question by comparing the views of female business students living in four distinct regions: the Arab Levant (Lebanon); the Arabian Gulf (Oman); Northwestern Europe (England) and Southeastern Europe (Romania). Using Weber's ideal types of authority, a comparison of the four groups reveals strong similarities between Omani and Lebanese women's views on leadership, thus supporting the existence of pan-Arab Implicit Leadership Theories (ILT). It is further found that such views on leadership reflect an overlapping of Arab tribal values with the `rational-legal' values associated with mass bureaucratization in the region.
Corporate Communication Challenges
Authors: Clausen Lisbeth
Published: March 2008

This study addresses cultural issues in business communication across cultures. The concept of 'negotiated' culture is employed, elaborated and applied to empirical data at organizational and individual contextual levels in intercultural encounters. Communication is viewed as a complex, multi-issued, and dynamic process in which global managers exchange meaning. A multi-contextual analysis is used to describe the dynamics and complexity of sense-making processes at the interface of meaning exchange in the collaboration between Danish and Japanese managers. In particular, the concept of 'negotiated' culture is employed to analyse strategic and operational communication between a Danish company and its alliance partner in the Japanese market. A significant amount of research represents a headquarters or western view of communication processes and cultural challenges in strategy implementation. The present study also includes the partner/Japanese view.
An analysis of the clinical and biologic significance of TP53 loss and the identification of potential novel transcriptional targets of TP53 in multiple myeloma
Authors: Xiong Wei , Wu Xiaosong , Starnes Sarah , Johnson Sarah K. , Haessler Jeff , Wang Siqing , Chen Lijuan , Barlogie Bart , Shaughnessy John D. , Zhan Fenghuang
Published: March 2008

TP53 is a tumor suppressor gene that functions as transcriptional regulator influencing cellular responses to DNA damage. Here we explored the clinical and transcriptional effects of TP53 expression in multiple myeloma (MM). We found that low expression of TP53, seen in approximately 10% of newly diagnosed patients, is highly correlated with TP53 deletion, an inferior clinical outcome, and represents an independent risk factor. Analysis of the expression of 122 known TP53 target genes in TP53-high vs -low MM cells from 351 newly diagnosed cases, revealed that only a few were highly correlated with TP53 expression. To elucidate TP53 regulatory networks in MM, we overexpressed TP53 in 4 MM cell lines. Gene expression profiling of these cell lines detected 85 significantly differentially expressed genes, with 50 up-regulated and 35 down-regulated. Unsupervised hierarchical clustering of myeloma samples from 351 newly diagnosed and 90 relapsed patients using the 85 putative TP53 target genes revealed 2 major subgroups showing a strong correlation with TP53 expression and survival. These data suggest that loss of TP53 expression in MM confers high risk and probably results in the deregulation of a novel set of MM-specific TP53-target genes. TP53 target gene specificity may be unique to different cell lineages.
Synergistic interactions between interferon-γ and TRAIL modulate c-FLIP in endothelial cells, mediating their lineage-specific sensitivity to thrombotic thrombocytopenic purpura plasma–associated apoptosis
Authors: Stefanescu Radu , Bassett Dustin , Modarresi Rozbeh , Santiago Francisco , Fakruddin Mohamad , Laurence Jeffrey
Published: March 2008

Microvascular endothelial cell (MVEC) injury coupled to progression of platelet microthrombi facilitated by ADAMTS13 deficiency is characteristic of idiopathic and HIV-linked thrombotic thrombocytopenic purpura (TTP). Cytokines capable of inducing MVEC apoptosis in vitro are up-regulated in both TTP and HIV infection. However, the concentrations of these cytokines required to elicit EC apoptosis in vitro are 2- to 3-log–fold greater than present in patient plasmas. We report that clinically relevant levels of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) and interferon (IFN)–γ act in synergy to induce apoptosis in dermal MVECs, but have no effect on large-vessel ECs or pulmonary MVECs. This reflects the tissue distribution of TTP lesions in vivo. Sensitivity to TTP plasma or TRAIL plus IFN-γ is paralleled by enhanced ubiquitination of the caspase-8 regulator cellular FLICE-like inhibitory protein (c-FLIP), targeting it for proteasome degradation. c-FLIP silencing with anti-FLIP short interfering RNA (siRNA) in pulmonary MVECs rendered them susceptible to TTP plasma– and cytokine-mediated apoptosis, while up-regulation of c-FLIP by gene transfer partially protected dermal MVECs from such injury. TTP plasma–mediated apoptosis appears to involve cytokine-induced acceleration of c-FLIP degradation, sensitizing cells to TRAIL-mediated caspase-8 activation and cell death. Suppression of TRAIL or modulation of immunoproteasome activity may have therapeutic relevance in TTP.
Metabolic responses to pyruvate kinase deletion in lysine producing Corynebacterium glutamicum
Authors: Becker Judith , Klopprogge Corinna , Wittmann Christoph
Published: March 2008

Background

Pyruvate kinase is an important element in flux control of the intermediate metabolism. It catalyzes the irreversible conversion of phosphoenolpyruvate into pyruvate and is under allosteric control. In Corynebacterium glutamicum, this enzyme was regarded as promising target for improved production of lysine, one of the major amino acids in animal nutrition. In pyruvate kinase deficient strains the required equimolar ratio of the two lysine precursors oxaloacetate and pyruvate can be achieved through concerted action of the phosphotransferase system (PTS) and phosphoenolpyruvate carboxylase (PEPC), whereby a reduced amount of carbon may be lost as CO2 due to reduced flux into the tricarboxylic acid (TCA) cycle. In previous studies, deletion of pyruvate kinase in lysine-producing C. glutamicum, however, did not yield a clear picture and the exact metabolic consequences are not fully understood.

Results

In this work, deletion of the pyk gene, encoding pyruvate kinase, was carried out in the lysine-producing strain C. glutamicum lysCfbr, expressing a feedback resistant aspartokinase, to investigate the cellular response to deletion of this central glycolytic enzyme. Pyk deletion was achieved by allelic replacement, verified by PCR analysis and the lack of in vitro enzyme activity. The deletion mutant showed an overall growth behavior (specific growth rate, glucose uptake rate, biomass yield) which was very similar to that of the parent strain, but differed in slightly reduced lysine formation, increased formation of the overflow metabolites dihydroxyacetone and glycerol and in metabolic fluxes around the pyruvate node. The latter involved a flux shift from pyruvate carboxylase (PC) to PEPC, by which the cell maintained anaplerotic supply of the TCA cycle. This created a metabolic by-pass from PEP to pyruvate via malic enzyme demonstrating its contribution to metabolic flexibility of C. glutamicum on glucose.

Conclusion

The metabolic flux analysis performed illustrates the high flexibility of the metabolic network of C. glutamicum to compensate for external perturbation. The organism could almost maintain its growth and production performance through a local redirection of the metabolic flux, thereby fulfilling all anabolic and catabolic needs. The formation of the undesired overflow metabolites dihydroxyacetone and glycerol, in the deletion mutant, however, indicates a limiting capacity of the metabolism down-stream of their common precursor glyceraldehyde 3-phosphate and opens possibilities for further strain engineering.
Pseudosarcomatous myofibroblastic lesion of the urinary bladder: A rare entity posing a diagnostic challenge and therapeutic dilemma
Authors: Lekas Alexandros , Parasi Aikaterini , Papathomas Thomas G , Papatsoris Athanasios G , Mennonna Maria Rozaria , Chrisofos Michail , Deliveliotis Charalambos , Lazaris Andreas C
Published: March 2008

Background

Pseudosarcomatous myofibroblastic lesions of the urinary bladder are relatively rare entities of an uncertain pathogenesis and benign indolent nature.

Case presentation

We present an extremely rare case of an ALK-1-positive pseudosarcomatous myofibroblastic lesion of the urinary bladder, which was initially misinterpreted as a low-grade leiomyosarcoma of myxoid subtype on histologic examination owing to prominent atypia, high mitotic activity, abnormal mitotic figures and infiltration of the bladder wall. Although the histologic features were suggestive of a sarcoma, the correct diagnosis was finally established and radical surgical treatment was subsequently avoided. The patient is currently free of disease without any evidence of tumor recurrence or metastasis at 3 years post-operatively.

Conclusion

The key differentiating point rests in distinguishing the aforementioned mass forming lesion from the myxoid subtype of low-grade leiomyosarcoma in order to avoid unnecessary radical therapy.
Effect of Pretreatment Distress on Daily Fatigue After Chemotherapy for Breast Cancer
Authors: Higgins Sara C. , Montgomery Guy H. , Raptis George , Bovbjerg Dana H.
Published: March 2008

Purpose

Fatigue is one of the most frequently reported and adverse effects of cancer chemotherapy. The present study tested the hypothesis that women's levels of emotional distress at the time of their initial outpatient chemotherapy treatment would predict the severity of their postinfusion fatigue.

Methods

Sixty stage I (32.6%) and II (67.4%) patients with breast cancer (mean age, 44.5 years) who were receiving standard outpatient chemotherapy participated. The independent variable, emotional distress, was assessed for “last night,” “this morning,” and “right now” with a visual analog scale (0 to 100). The dependent variable, post-treatment fatigue (PTF), was assessed (0 to 100) over each of the subsequent 6 days using end-of-day diaries, which also included assessments of distress and nausea (0 to 100). For the statistical analyses, post-treatment fatigue was divided into three phases with means calculated for days 1 through 2 (phase 1), 3 to 4 (phase 2), and 5 to 6 (phase 3).

Results

Consistent with the study hypothesis, patients' pretreatment distress level in the clinic was a significant (P < .001) predictor of PTF. There was also a significant (P < .025) interaction with phase, with distress becoming a predictor of PTF after phase 1. Multivariate analysis indicated that prior levels of distress were not independent predictors of PTF.

Conclusions

This study is the first to demonstrate time-specific effects of pretreatment distress on PTF. Possible mechanisms of these effects now warrant investigation, as do possible benefits of brief interventions to reduce patient distress immediately before treatment.
Radial-basis-function-based feedforward—feedback control for air—fuel ratio of spark ignition engines
Authors: Zhai Y J , Yu D L
Published: March 2008

In this paper, a feedforward—feedback control is developed for the air—fuel ratio (AFR) of spark ignition engines using neural network estimators. To maintain the AFR at stoichiometric value, the throttle angle change is seen as a disturbance, from which the air flowrate is predicted. The injected fuel is also predicted using the inverse of the fuel injection dynamics. The proposed method is evaluated on an engine simulation benchmark and the performance is shown much improved over proportional—integral control. The new method needs moderate computation and therefore has strong potential to be used in production engines.
The effects of fuel dilution in a natural-gas direct-injection engine
Authors: McTaggart-Cowan G P , Rogak S N , Hill P G , Munshi S R , Bushe W K
Published: March 2008

This study reports the effects of fuelling a heavy-duty single-cylinder research engine with pilot-ignited late-cycle direct-injected natural gas diluted with 0, 20, and 40 per cent nitrogen. The combustion duration is unaffected while its intensity is reduced and its stability is increased. Emissions of nitrogen oxides, particulate matter, hydrocarbons, and carbon monoxide are all reduced, with no effect on the engine's performance and efficiency. The results indicate the benefits of increased in-cylinder turbulence and are of particular relevance when considering fuel composition variations with non-conventional sources of gaseous fuels.
Aspects of acoustic emission attenuation in steel pipes subject to different internal and external environments
Authors: Shehadeh M. F. , Abdou W. , Steel J. A. , Reuben R. L.
Published: March 2008

The current paper follows from earlier work on the propagation of acoustic emission (AE) in pipelines and addresses, in particular, the effects of the internal and external environment. Specifically, experiments have been carried out on a 5.5 m length of pipe with and without water inside and with various external environments chosen to simulate burial with various levels of soil saturation. The AE signature of a simulated source was recorded at various distances along the pipe with various environments and the data were analysed in the time and frequency domains to isolate the effect of interfaces on the distortion of propagating AE waves. It is shown that AE transmission is affected markedly by both the internal and the external environments, but that some components of the wave are affected less than others. A simple attenuation model is presented, which takes into account the losses at the interfaces, and this suggests that much of the attenuation is attributable to waves moving in the body of the pipe wall rather than on its surface. The findings will be of value in the practical detection and location of active defects in pipes, where the internal and external environments may vary. One might expect a source to generate a particular time-frequency signature, and it is of interest to know how much this source signature will become distorted when sensed at some distance.
Determination of optimized non-gasketed flange geometry for safe stress and no leak condition: Finite-element analysis approach
Authors: Abid M. , Iqbal M.
Published: March 2008

Performance of a flange joint is characterized mainly due to its ‘strength’ and ‘sealing capability’. Available design rules for flange joints are mainly concerned with the strength of the flanges and do not sufficiently consider for their sealing. Being continuous problems faced by the gasketed flange joints for strength and sealing based on concluded ‘dynamic mode of load’, non-gasketed joints are recommended as an alternative. The current paper presents three-dimensional non-linear finite-element analysis of non-gasketed flange joint with different flange surface profiles (positive taper, negative taper, and zero taper angles) to find out the most optimal flange geometry for safe stress and no-leak conditions under bolt up and internal pressure loading. Based on the results, optimum flange geometry is selected and further analysed under proof test pressure. A ‘static mode of load’ in positive taper angle flange is concluded, ensuring proper joint sealing, and strength.
A study on the sealing performance of flange joints with gaskets under external bending using finite-element analysis
Authors: Mathan G. , Prasad N Siva
Published: March 2008

The effect of external bending on flange joints in pipelines, pressure vessels, and pressure vessel nozzles is significant and difficult to assess. In the current work, the sealing performance of a gasketed flange joint under external bending has been studied by using a three-dimensional finite element analysis, considering the non-linear material behaviour of the gaskets. Spiral wound gaskets and non-metallic gaskets with various sealing materials are considered. Results show that the allowable bending moment on a flange joint depends on the tightness required, type of gasket, and its deformation characteristics. Gaskets with elastomeric sealing materials show good performance against leakage under external bending.
Distributed control approach for small-scale energy zones
Authors: Trichakis P , Taylor P C , Coates G , Cipcigan L M
Published: March 2008

A small-scale energy zone (SSEZ) is a conceptual future low-voltage distribution network (LVDN) configuration, containing controllable small-scale embedded generators (SSEGs), energy storage units, and consumer demands. The SSEZ concept, coupled with an appropriate active control approach, aims to increase the commercial value and environmental impact of SSEGs. Such an approach must overcome the SSEZ's LVDN constraints and meet its operational goals. The current paper presents preliminary research to: (a) identify the SSEZ control requirements, (b) select an appropriate control approach, and (c) conduct an initial approach evaluation. A distributed control approach has been selected and realized through the use of a multi-agent system (MAS). This distributed control approach offers advantages with respect to scalability and openness, resilience and reliability, and communication efficiency. This control approach is applied to a case study SSEZ in order to evaluate its ability to overcome the distribution network constraints and to meet its operational goals. The research described in this paper brings together power systems and MAS knowledge through collaboration between the Energy and Mechanics Research Groups in the School of Engineering at Durham University.
Innovative study of co-axial normal and inverse diffusion flames
Authors: Kamal M M
Published: March 2008

An experimental work was performed to investigate the co-axial normal/inverse diffusion flames at both unbound and confined conditions. Three novel burner designs were employed such that initially co-axial air and fuel streams issuing from an inverse flame burner port were combusted within a confinement and then mixed with an outer atmosphere thus involving an outer normal flame. Strongly turbulent conditions were enforced through flow restriction, introducing cross-flow opposing jets, extending the aerodynamic expanding zones, and jet splitting. Such parametric variation was coupled with changes in the flow areas and relative velocities. With the vertically straight design, decreasing the covering plate punching diameter or its separation gap above the supplying air tube significantly decreased the exhausted unburned hydrocarbon concentrations. Sufficiently high air jet velocities led to lifted flames with an associated fuel entrainment. The peak flame temperature reduction to around 1300 °C highlighted the decrease in the maximum NOx concentrations. Enhanced qualitative/quantitative flame characteristics were also obtained upon employing an expanding interior wall design. The fuel/air mixing and recirculation were significantly enhanced by extending the confining wall such that the combustion efficiency was optimized by the flow dynamics of the inverse flame inner air supply. The maximum unburned hydrocarbon and carbon monoxide concentrations were 0.57 per cent and 800 ppm, respectively. In the third design, the mixing rates were increased by splitting the fuel jet so that the enlarged flame envelope increased the combustion efficiency at the proper relative jet velocities. The turbulence characteristics were computationally addressed by highlighting the role of jet shear layers and recirculation in augmenting the combustion efficiency and stability.
Investigation of suction process of a large R134a scroll compressor
Authors: Cui M , Sauls J
Published: March 2008

The suction process of a scroll compressor was investigated. The investigation started from the numerical simulation of the entire scroll compressor working process. The simulation included the upper main bearing housing, thrust plate, scrolls, dummy and discharge ports, check valve, plenum, and discharge line. The basic geometric features and physical mechanisms that the scroll compressor performance is associated with were simulated first. The working fluid was Refrigerant 134a. The suction process was studied as a part of the integrated working environment. The fundamental mechanism of the suction process was defined. The interaction of the compressor design features was quantified. The overall parameters were calculated from the field quantities. The relationship between design details, flow physics, and performance characteristics was established. The methodology developed and the data obtained can be applied to the design and optimization of scroll compressors.
A comparison between conventional recuperative gas turbine and hybrid solid oxide fuel cell—gas turbine systems with direct/indirect integration
Authors: Sánchez D , Chacartegui R , Sánchez T , Martínez J , Rosa F
Published: March 2008

Conventional recuperative micro gas turbines have a 30 per cent low heating value (LHV) maximum efficiency at full load. Therefore, if they are to be used in a potential distributed energy scenario, solutions must be developed that increase efficiency. An innovative gas turbine-based technology is the fuel cell — gas turbine hybrid system. This work is aimed at studying how the basic performance of a conventional Brayton cycle changes when heat addition is done at a fuel cell. Two layouts are considered: a direct system where the compressor feeds the fuel cell directly and an indirect system where only heat is transferred between subsystems.

Direct and indirect systems have been studied at full and part load, concluding that the efficiency versus pressure ratio curves of hybrid systems change substantially with respect to a traditional gas turbine; part-load efficiency hardly decreases.

Maximum efficiency of hybrid systems doubles the efficiency of state of the art micro gas turbine and remains high at part load. Furthermore, the benefit of a certain increase in temperature is higher for hybrid systems than for conventional engines.

Finally, a simple economic analysis shows that the total installation and operation/maintenance costs of hybrid systems make them competitive against conventional gas turbines.
Effective utilization of low-grade steam in an ammonia—water cycle
Authors: Senthil Murugan R , Subbarao P M V
Published: March 2008

Effective utilization of low-grade steam in a Rankine cycle power plant is one of the challenging tasks for researchers. In a condensing turbine, last few stages of the turbine operate in two phase region leading to losses due to flow of wet steam, which results loss of work in low pressure turbine. Either wet or saturated steam normally called low grade is difficult to handle in a steam turbine due to its higher specific volume. Major portion of the heat in the cycle is rejected to cooling water, which results in thermal pollution of the environment and higher energy loss. Ammonia—water cycle or Kalina cycle is more efficient for the utilization of various low grade heat sources such as gas turbine exhaust gas, geothermal hot water, exhaust from steel plant etc. In this work, a new methodology was proposed for the utilization of low-grade steam in ammonia—water cycle to obtain a better power output and higher plant efficiency. The suggested ammonia—water cycle that utilizes low-grade steam produces higher-power output and it is more efficient than the Rankine steam cycle utilizing the low-grade steam and operates on a condensing mode.
Designing Pricing Contracts for Boundedly Rational Customers: Does the Framing of the Fixed Fee Matter?
Authors: Ho Teck-Hua , Zhang Juanjuan
Published: March 2008

The format of pricing contracts varies substantially across business contexts, a major variable being whether a contract imposes a fixed fee payment. This paper examines how the use of the fixed fee in pricing contracts affects market outcomes of a manufacturer-retailer channel. Standard economic theories predict that channel efficiency increases with the introduction of the fixed fee and is invariant to its framing. We conduct a laboratory experiment to test these predictions. Surprisingly, the introduction of the fixed fee fails to increase channel efficiency. Moreover, the framing of the fixed fee does make a difference: an opaque frame as quantity discounts achieves higher channel efficiency than a salient frame as a two-part tariff, although these two contractual formats are theoretically equivalent.

To account for these anomalies, we generalize the standard economic model by allowing the retailer's utilities to be reference dependent so that the up-front fixed fee payment is perceived as a loss and the subsequent retail profits as a gain. We embed this reference-dependent utility function in a quantal response equilibrium framework where the retailer is allowed to make decision mistakes due to computational complexity. The key prediction of this behavioral model is that channel efficiency decreases with loss aversion for sufficiently Nash-rational retailers. Consistent with this prediction, the estimated loss-aversion coefficient is 1.37 in the two-part tariff condition, significantly higher than 1.27 in the quantity discount condition. At the same time, loss aversion dominates contract complexity in explaining the data. Lastly, we conduct a follow-up experiment to confirm the central role of loss aversion as a behavioral driver. In one condition, the retailer becomes less loss averse when we temporally compress the fixed fee payment and the realization of retail profits, which supports the loss aversion theory. In the other condition, the retailer's contract acceptance rate does not decline when we reward the manufacturer a higher cash payment for each experimental point earned, which rules out the competing hypothesis that the retailer rejects contract offers due to fairness concerns.
Between Daylight and Darkness: Forever and Silent Light
Authors: Johnson William
Published: March 2008

This comparative essay deals with two films, Forever (a documentary about the Père Lachaise cemetery in Paris directed by Heddy Honigman), and Silent Light (a fiction film set among Mexican Mennonites, and featuring a non-professional cast directed by Carlos Reygadas), both of which focus on love and death.
The Wire: The Complete Fourth Season
Authors: Tyree J. M.
Published: March 2008

An essay on the fourth season DVD boxed set of the politically uncompromising HBO series, The Wire (created by Ed Burns and David Simon), an urban crime drama of unprecedented complexity that is unusual in featuring a cast largely composed of African Americans.
Video Frame Enlargments
Authors: Kawin Bruce
Published: March 2008

This essay discusses frame-enlargment technology, comparing digital and photographic alternatives and concluding, after the analysis of specific examples, that frames photographed from a 35mm print are much superior in quality.
Growth of nanocrystalline PbS within a glass
Authors: Mukherjee M. , Datta A. , Chakravorty D.
Published: March 2008

Nanocrystalline PbS has been grown within a phase-separated oxide glass of composition 10 Na2O, 15 PbO, 17 CaO, 3 Bi2O3, and 55 SiO2 (in mole %) by passing H2S gas over it at temperatures varying from 773 to 943 K. The particle size ranged from 2.5 to 12.9 nm. The dc resistivity of composites of nanocrystalline PbS and the phase separated glass has been measured over the temperature range 300 to 670 K. The resistivity variation in the temperature range 550 to 670 K is characterized by the sodium ion migration in the glass with an activation energy, ∼1.2 eV. The resistivity in the range 300 to 500 K was controlled by conduction in PbS particles with the estimated band gap showing an increase with a decrease in the particle size.
Rapid thermal recrystallization of amorphous silicon films
Authors: Beshkov G. D. , Dimitrov D. B. , Lazarova V. , Koprinarova J. , Gesheva K. , Vlaev E.
Published: March 2008

In this work the properties of polycrystalline silicon layers obtained by rapid thermal annealing have been discussed. Amorphous silicon layers with thickness of 3000 Å have been deposited on silicon wafers in rf sputtering system. The layers were annealed for 15 s to 5 min at temperatures in the range 800–1200 °C in vacuum 5 × 10−5 Torr. A correlation was established between structure, morphology, sheet resistance, and the parameters of the RTA annealing.
On the formation of solid state crystallized intrinsic polycrystalline germanium thin films
Authors: Meng Zhiguo , Jin Zhonghe , Bhat Gururaj A. , Chu Paul , Kwok Hoi S. , Wong Man
Published: March 2008

A two-step heat treatment process has been employed to crystallize low pressure deposited thin films of amorphous germanium. Large grain p-type polycrystalline germanium with a Hall effect hole mobility of greater than 300 cm2/Vs has been obtained. Films with near intrinsic conductivity, necessary for the construction of practical enhancement-mode insulated-gate thin film transistors, were obtained by introducing phosphorus as a compensating dopant. High Hall effect electron mobility of 245 cm2/Vs has been measured on the resulting n-type polycrystalline germanium thin films.
Quantum size effect of ZnSe microcrystal-doped SiO2 glass thin films prepared by RF-sputtering method
Authors: Hayashi Masayuki , Iwano Takafumi , Nasu Hiroyuki , Kamiya Kanichi , Sugimoto Naoki , Hirao Kazuyuki
Published: March 2008

Semiconductor ZnSe microcrystal-doped SiO2 glass thin films were prepared by the RF-magnetron sputtering method. The particle size of ZnSe microcrystals in the films depended on sputtering conditions such as input power, substrate temperature, and relative surface area ratio (ZnSe/SiO2) in the target. The blue shift of the optical absorption edge was observed in these glass films. This blue shift energy was explained in terms of the independent confinement of electrons and positive holes, Coulomb force and the influence of a collapsed exciton and the dielectric constant of the matrix glass being taken into consideration.