bluuebunny/crossref_metadata_2025 huggingface dataset:
A Weighted AMMI Algorithm to Study Genotype‐by‐Environment Interaction and QTL‐by‐Environment Interaction
Authors: Rodrigues Paulo C. , Malosetti Marcos , Gauch Hugh G. , van Eeuwijk Fred A.
Published: May 2014

Genotype‐by‐environment (G × E) interaction (GEI) and quantitative trait locus (QTL)‐by‐environment interaction (QEI) are common phenomena in multiple‐environment trials and represent a major challenge to breeders. The additive main effects and multiplicative interaction (AMMI) model is a widely used tool for the analysis of multiple‐environment trials, where the data are represented by a two‐way table of G × E means. For complete tables, least squares estimation for the AMMI model is equivalent to fitting an additive two‐way ANOVA model for the main effects and applying a singular value decomposition to the interaction residuals, thereby implicitly assuming equal weights for all G × E means. However, multiple‐environment data with strong GEI are often also characterized by strong heterogeneous error variation. To improve the performance of the AMMI model in the latter situation, we introduce a generalized estimation scheme, the weighted AMMI or W‐AMMI algorithm. This algorithm is useful for studying GEI and QEI. For QEI, the W‐AMMI algorithm can be used to create predicted values per environment that are subjected to QTL analysis. We compare the performance of this combined W‐AMMI and QTL mapping strategy to direct QTL mapping on G × E means and to QTL mapping on AMMI‐predicted values, again with QTL analyses for individual environments. Finally, we compare the W‐AMMI QTL mapping strategy, with a multi‐environment mixed model QTL mapping approach. Two data sets are used: (i) data from a simulated pepper (Capsicum annuum L.) back cross population using a crop growth model to relate genotypes to phenotypes in a nonlinear way, and (ii) the doubled‐haploid Steptoe × Morex barley (Hordeum vulgare L.) population. The QTL analyses on the W‐AMMI‐predicted values outperformed the QTL analyses on the G × E means and on the AMMI‐predicted values, and were very similar to the mixed model QTL mapping approach with regard to the number and location of the true positive QTLs detected, especially for QTLs associated with the interaction and for environments with higher error variance. W‐AMMI analysis for GEI and QEI provides an easy‐to‐use and robust tool with wide applicability.
Broccoli Cultivar Performance under Organic and Conventional Management Systems and Implications for Crop Improvement
Authors: Renaud Erica N. C. , Lammerts van Bueren Edith T. , Paulo Maria João , van Eeuwijk Fred A. , Juvik John A. , Hutton Mark G. , Myers James R.
Published: May 2014

To determine if present commercial broccoli cultivars meet the diverse needs of organic management systems, such as adaptation to low N input, mechanical weed management, and no chemical pesticide use, and to propose the selection environments for crop improvement for organic production, we compared horticultural trait performance of 23 broccoli cultivars (G) under two management (M) systems (organic and conventional) in two regions of the United States (Oregon and Maine), including spring and fall trials. In our trials, location and season had the largest effect on broccoli head weight, with Oregon outperforming Maine, and fall trials outperforming spring plantings. M main effects and G × M interactions were often small, but G × M × E (location and season) were large. Cultivars with both greater head weight and stability under conventional conditions generally had high head weight and stability under organic growing conditions, although there were exceptions in cultivar rank between management systems. Larger genotypic variances and somewhat increased error variances observed in organic compared with conventional management systems led to repeatability for head weight and other horticultural traits that were similar or even higher in organic compared with conventional conditions. The ratio of correlated response (predicting performance under organic conditions when evaluated in conventional conditions) to direct response (predicted performance in organic when evaluated under organic conditions) for all traits was close to but less than 1.0 with the exception of bead uniformity. This would imply that in most cases, direct selection in an organic environment could result in a more rapid genetic gain than indirect selection in a conventional environment.
Genetic Improvement of U.S. Soybean in Maturity Groups II, III, and IV
Authors: Rincker Keith , Nelson Randall , Specht James , Sleper David , Cary Troy , Cianzio Silvia R. , Casteel Shaun , Conley Shawn , Chen Pengyin , Davis Vince , Fox Carolyn , Graef George , Godsey Chad , Holshouser David , Jiang Guo‐Liang , Kantartzi Stella K. , Kenworthy William , Lee Chad , Mian Rouf , McHale Leah , Naeve Seth , Orf James , Poysa Vaino , Schapaugh William , Shannon Grover , Uniatowski Robert , Wang Dechun , Diers Brian
Published: May 2014

Soybean improvement via plant breeding has been critical for the success of the crop. The objective of this study was to quantify genetic change in yield and other traits that occurred during the past 80 yr of North American soybean breeding in Maturity Groups (MGs) II, III, and IV. Historic sets of 60 MG II, 59 MG III, and 49 MG IV soybean cultivars, released from 1923 to 2008, were evaluated in field trials conducted in 17 U.S. states and one Canadian province during 2010 to 2011. Averaged over 27 MG II and MG IV and 26 MG III site‐years of data, the estimated rates of yield improvement during the 80 yr were 23 kg ha–1 yr–1 for MGs II and III, and 20 kg ha–1 yr–1 for MG IV cultivars. However, a two‐segment linear regression model provided a better fit to the data and indicated that the average current rate of genetic yield gain across MGs is 29 kg ha–1 yr–1. Modern cultivars yielded more than old cultivars in all environments, but particularly in high‐yielding environments. New cultivars in the historic sets used in this study are shorter in height, mature later, lodge less, and have seeds with less protein and greater oil concentration. Given that on‐farm soybean yields in the United States are also increasing at a rate of 29 kg ha–1 yr–1, it can be inferred that continual release of greater‐yielding cultivars has been a substantive driver of the U.S. on‐farm realized yield increases.
Phosphorus Reduction in Turfgrass Runoff Using a Steel Slag Trench Filter System
Authors: Wang Zan , Bell Gregory E. , Penn Chad J. , Moss Justin Q. , Payton Mark E.
Published: May 2014

Excessive concentrations of P can lead to the deterioration of surface waters through eutrophication. This study was conducted to test the effectiveness of a trench filter system for P removal from runoff and to determine the effect of P fertilizer on P losses in runoff from bermudagrass [Cynodon dactylon L. (Pers.)]. A total of 12 plots on a uniform 5% slope covered with ‘Astro’ bermudagrass mowed at 38 mm were used to collect pre‐ and postfiltered runoff from 14 natural or simulated precipitation events that occurred from March through September 2012. Runoff filtered by steel slag contained from 14.2 to 49.2% lower dissolved P concentrations than runoff filtered through an inert gravel control. The P concentrations in runoff from fertilized plots were always greater than unfertilized plots. The difference between P concentrations from the fertilized and unfertilized treatments tended to decline with each runoff event from 13.1 mg L–1 in an initial event after fertilization to 1.6 mg L–1, 133 d and nine runoff events later. Trench filter systems could be used to remove a portion of the P in runoff from turfgrass areas.
Large Crabgrass, White Clover, and Hybrid Bermudagrass Athletic Field Playing Quality in Response to Simulated Traffic
Authors: Brosnan J.T. , Dickson K.H. , Sorochan J.C. , Thoms A.W. , Stier J.C.
Published: May 2014

Athletic field playing quality encompasses both aesthetics as well as athlete‐to‐surface interactions that can affect injury incidence. Legislation restricting the use of herbicides on athletic fields may lead to increases in problematic weeds, such as large crabgrass (Digitaria sanguinalis L.) and white clover (Trifolium repens L.), which could reduce athletic field playing quality and potentially increase potential for athletic injuries. Research was conducted at the University of Tennessee Center for Athletic Field Safety (Knoxville, TN) during 2012 to 2013 to evaluate the playing quality of large crabgrass and white clover compared with weed‐free hybrid bermudagrass (C. dactylon ⋅ C. transvaalensis Burtt‐Davy, ‘Tifway’). All plots (3 by 3 m) were maintained as monostands and subjected to 18 simulated traffic events with a Cady traffic simulator each autumn over 2 yr. Large crabgrass and white clover lost green cover approximately 12 times faster than hybrid bermudagrass in this study. Consequently, surface hardness values on large crabgrass and white clover plots were ∼48 to 52% higher than those measured on hybrid bermudagrass after 18 simulated traffic events were applied. Changes in both surface hardness and rotational resistance were significantly correlated (P < 0.0001) to changes in green cover following simulated traffic. Our findings indicate that groundcover domination by weeds, such as large crabgrass and white clover, compromises the aesthetics and safety of natural grass athletic fields. Additional research is needed to evaluate athletic field playing quality on polystands of hybrid bermudagrass, large crabgrass, and white clover to determine acceptable thresholds of weed cover for player safety. Information of this nature would be useful for justifying various weed control measures such as herbicide applications.
Genomewide Prediction Accuracy within 969 Maize Biparental Populations
Authors: Lian Lian , Jacobson Amy , Zhong Shengqiang , Bernardo Rex
Published: May 2014

In genomewide selection, the expected correlation between predicted and true genotypic values (rMG) has been previously derived as a function of the training population size (N), heritability (h2), and effective number of chromosome segments (Me) affecting the trait. Our objectives were to determine: (i) the mean and variability of rMG in 969 biparental maize (Zea mays L.) breeding populations for seven traits, (ii) if rMG can be predicted in advance, and (iii) how N, h2, and number of markers (NM) affect rMG. We modified a previous equation for expected rMG to account for linkage disequilibrium (r2) between a marker and a quantitative trait locus (QTL). Across the 969 populations, the mean and range (in parentheses) of observed rMG was 0.45 (−0.59, 1.03) for grain yield, 0.59 (−0.34, 0.96) for moisture, 0.55 (−0.24, 1.10) for test weight, 0.49 (−0.22, 1.04) for stalk lodging, 0.41 (−0.30, 0.93) for root lodging, 0.47 (−0.45, 0.97) for plant height, and 0.42 (−0.43, 0.94) for ear height. The observed rMG values were centered around the expected rMG when r2 was accounted for, but the observed rMG had a large spread around the expected rMG. The r2(Nh2)1/2 had the strongest association with observed rMG. When r2(Nh2)1/2 exceeded 8, the proportion of rMG equal to or larger than 0.50 reached 90% among all the population–trait combinations. We conclude it is difficult to predict rMG in advance, but that rules of thumb based on r2(Nh2)1/2 can help achieve a high rMG.
Anticipating Challenges with In‐Building Disinfection for Control of Opportunistic Pathogens
Authors: Rhoads William J. , Pruden Amy , Edwards Marc A.
Published: May 2014

A new American Society of Heating, Refrigerating and Air‐Conditioning Engineers (ASHRAE) standard for control of Legionella (ASHRAE Standard 188, 2013) emphasizes use of in‐building disinfection techniques to reduce the exposure of at‐risk consumers to opportunistic pathogens in premise plumbing (OPPPs). This standard and other recommendations for OPPP control have implications for scaling in and corrosion of plumbing systems, which can sometimes adversely affect the efficacy of the disinfection method and physical integrity of the plumbing system, prompting this proactive critical review of challenges associated with implementation of Standard 188.
Modeling Heterotrophic Bacteria in Plumbing System of Drinking Water
Authors: Chowdhury Shakhawat , Al‐Zahrani Muhammad
Published: May 2014

This study investigated occurrences of heterotrophic (HPC) bacteria and developed predictive models for HPC bacteria in plumbing pipes (PP) and hot water tanks (HWT) of two houses in Dhahran (Saudi Arabia). Heterotrophic bacteria in PP and HWT were observed to be 2.4 to 5.3 and 0.4 to 5.9 times the HPC bacteria in water distribution system (WDS), respectively. Three linear, one nonlinear, and one neural network models were investigated to predict HPC bacteria in PP and HWT. Significant factors for bacteria regrowth in PP and HWT were identified through numerical and graphical techniques. The R2 values of the models varied between 0.57 and 0.96, indicating moderate to excellent predictive ability for HPC bacteria in PP and HWT. The models were found to be statistically significant, which were also validated using additional data. These models can be used to predict HPC bacteria regrowth from WDS to PP and HWT, and could help to predict exposure and risks.
Moving beyond Idealistically Narrow Discourses in Citizenship Education
Authors: Fischman Gustavo E. , Haas Eric
Published: May 2014

The main goal of this article is to provide conceptual guidelines to move the pedagogical debate in the field of citizenship education beyond idealistically narrow models. We begin by providing an overview of key shortcomings presented in most citizenship education programs, specifically in the United States of America. The second section presents the conceptual perspective of embodied cognition to discuss the prevalent metaphors and prototypes related to the notion of ‘the nation as a family’ commonly used in understanding citizenship education. The third and final section concludes with a set of suggestions for reconceptualizing the field of citizenship education using the tools of embodied cognition.
Learning through Civic Participation: Policy Actors' Perspectives on Curriculum Reform Involvement in Ontario
Authors: Pinto Laura Elizabeth
Published: May 2014

When citizens participate in policy production, the advantages go beyond policy outcomes — though the presumption is that participation leads to better public policy. Robust democracy characterized by agonistic exchanges among policy actors ought to encourage learning, dialogue, empowerment, equity, and a shared spirit of inquiry. This article describes and analyses citizen participation in curriculum policy production during the late 1990s based on archival documents and interviews with 16 policy actors (including writers, bureaucrats, and consultation participants). Their reflections on the process reveal unintended learning about politics, government, and the cultivation of civic skills arising out of interaction with others in different roles and on different ends of the political spectrum. While the analysis reveals how some describe the process as ‘radicalizing’ enlightenment, the findings point to a number of areas for improving opportunities for learning in formal policy production processes, as well as areas for further empirical investigation.
Institutional Assessment: Between Political Pressing Needs and School Improvement Needs
Authors: Méndez Juan Manuel álvarez
Published: May 2014

This article presents, through a critical analysis, a reflection on a noticeable change that focuses on some aspects related to the assessment of different parts of the educational system. In particular, it concentrates on the assessment of teaching institutions which has been considered by authorities that are distant from the school life and from what takes place in the classrooms; an assessment that affects both the teaching institutions and the social organisations, and that has the teachers as its main objective. This is a new approach whose origin can be found in the political demands of a neo-liberal ideology.
The Academisation of Emerging Professions: Implications for Universities, Academics and Students
Authors: McEwen Celina , Trede Franziska
Published: May 2014

Although Australian universities have delivered professional education alongside liberal education since their inception, the more recent introduction of emerging professions into universities' curricula indicates a greater blurring of the boundaries within the higher education sector, where universities are increasingly delivering courses formerly within the realm of technical or further education colleges. This vocationalisation of universities is in response to an imposed economic imperative, and neo-liberal rhetoric. In this article, the authors discuss some of the reasons and consequences of the academisation of emerging professions for universities, their academics and students. They argue that by lacking a deliberate approach and allowing a blurring of the lines between liberal, professional and vocational education, universities run the risk of failing to deliver on their promise of employability and social inclusion. The authors also suggest that the current situation can, however, provide an opportunity for universities to educate a deliberate professional by adopting a pedagogical approach that seeks to develop undergraduates' technical skills and knowledge, as well as an understanding of when and how to align, innovate or oppose the legitimised practices, cultures and identities of their chosen profession or occupation.
‘Shut Up and Teach’: Confronting the Power of Racialized Hero Discourses of Soldier and Nation
Authors: Montgomery Ken
Published: May 2014

This article offers a discourse analysis of a sample of negative responses to the public position of a group of Canadian professors who contended that a particular non-governmental scholarship glorified war and was indicative of both a creeping Canadian imperialism and an expanding military-educational complex. The author argues that the powerfully negative reaction to the critique of the Project Hero scholarships was rooted in a nationalist fantasy of Canada as a benevolent do-gooder, and dependent upon both overt and subtle forms of racism. The article also aims to prompt a dialogue about the extent to which public intellectuals and public universities are free to engage openly in critique of power rooted in the articulation of nationalism, militarism and racism.
Formerly NEET Young People's Pathways to Work: A Case-Study Approach
Authors: Russell Lisa
Published: May 2014

The recession in the United Kingdom has had a disproportionate effect on young people's employment opportunities, rendering many of them, especially those with low-level qualifications, ensnared in insecure, low-paid work. Findings from two multinational private sector company case studies, incorporating the perspectives of management staff, young people working within them, career support service practitioners and Jobcentre Plus managers, reveal that many young people want to work, but have difficulty in finding and retaining paid employment. Previously NEET (not in employment, education or training) young people, especially those from lower socio-economic backgrounds, tend to access work via informal pathways and obtain knowledge about the workplace via informal means, rendering them less likely to gain and retain secure, well-paid employment. Private sector employers, career guidance and support practices are progressively moving towards more formal routes of gaining and retaining staff. Integrated, holistic systems that support both the young person and employer are required to help previously NEET young people secure relevant job opportunities.
Policy Governance without Government in European Higher Education
Authors: Kolokitha Magdalini
Published: May 2014

This article argues that the Bologna process, as a set of policy initiatives which exists at the margins of the European Union framework, embodies a case of governmentality in a context of governance without government. This is due to the distinctive regulatory characteristics of the Bologna process, which encompass its non-legislative character; the voluntary adaptation to, and participation of the member states in, the process; the extension of the process to non-European Union members; and, finally, its peculiarity as a set of common guidelines, the realisation of which differs within each member state. These characteristics introduce a modality of policy governance in European higher education that aims to tackle the challenges of globalisation beyond traditional forms of government.
The Place of Emotion in Teacher Reflection: Elias, Foucault and ‘Critical Emotional Reflexivity’
Authors: Zembylas Michalinos
Published: May 2014

This article argues that recognizing the emotional aspects of reflexivity offers insights into the mechanisms with which teacher reflection occurs and becomes a disciplinary or subversive strategy. Particularly, the notion of ‘critical emotional reflexivity’ is theorized as a concept and praxis that not only acknowledges how reflexive processes are deeply emotional, but also interrogates how emotions are entangled with power relations and reflexive processes to legitimize or delegitimize certain teaching practices. A theoretical framework to ground the concept of critical emotional reflexivity in teaching is proposed; this framework is based on the theories of Norbert Elias and Michel Foucault, and involves a more complex understanding of emotion as an integral part of professional experience constituted in the interplay of personal, cultural, social and political aspects. The article concludes with a discussion about the potential contribution of critical emotional reflexivity as a theoretical and pedagogical ‘tool’ in teaching and teacher professional development.
Questioning Postclassic Continuity at Baking Pot, Belize, Using Direct AMS14C Dating of Human Burials
Authors: Hoggarth Julie A , Culleton Brendan J , Awe Jaime J , Kennett Douglas J
Published: May 2014

Archaeologists working in the Belize Valley have argued for the persistence of Maya populations from the Classic (AD 300–900) through Postclassic (AD 900–1500) periods since Gordon Willey's groundbreaking settlement survey and excavation work in the 1950s. This is contrary to the trajectory recorded in some parts of the Maya region where there is clear evidence for political disruption and population decline at the end of the Classic period. The argument for continuous Classic to Postclassic occupation in the Belize Valley remains ambiguous due to researchers' reliance on relative ceramic chronologies. This article reports the results of direct accelerator mass spectrometry (AMS) radiocarbon dating of human skeletons (n= 12) from the important center of Baking Pot, Belize, which is thought to provide some of the best ceramic evidence for continuity in the valley. The AMS dates show a long span of mortuary activity between the Middle Preclassic and Late Classic periods (405 cal BC to cal AD 770), with a hiatus in activity during the Early Postclassic (cal AD 900–1200) and subsequent activity in the Late Postclassic (cal AD 1280–1420). These results are not consistent with the idea that Baking Pot was occupied continuously from the Classic through Postclassic periods. This work highlights the need for additional AMS14C work at Baking Pot and elsewhere to establish absolute chronologies for evaluating the political and demographic collapse of Classic Maya regional centers.
Systematic study of deformation effects on fusion cross-sections using various proximity potentials
Authors: Rajbongshi Tapan , Kalita Kushal
Published: May 2014

The influence of static quadrupole and hexadecapole (positive & negative) deformation of targets are studied using eleven different versions of nuclear potentials. The height and position of the interaction barrier for the reactions induced by spherical projectile (16O) on the deformed targets such as 166Er, 154Sm and 176Yb have been estimated. It is found that the nucleus-nucleus potential strongly depends on the value of the deformation parameters and orientation of the target. The experimental fusion cross-section of the reactions 16O + 176Yb, 16O +166Er and 16O +154Sm are investigated by applyingWong’s formula using various parameterizations of the proximity potential as well as an assessment of the results of a multi-dimensional barrier penetration model (BPM). The fusion cross-sections by Prox 77, Prox 88, Prox 00, Prox 00DP, Denisov DP, Bass 80, CW 76 and AW 95 potentials are found to be better than the rest in comparison to experimental data.
Centripetal Endoscopic Sinus Surgery in Chronic Rhinosinusitis: A 6-year Experience
Authors: de Moreta Guillermo Sanjuan , Cardoso-López Isabel , Poletti-Serafini Daniel
Published: May 2014

Background

Despite technical advances in the tools designed to facilitate endoscopic nasosinusal surgery, the approach used, functional endoscopic sinus surgery, has not undergone major modifications since it was first described in the late 1980s. Centripetal endoscopic sinus surgery (CESS) is a new approach based on taking the medial wall of the orbit and the anterior cranial base as constant dissection landmarks. The aim of this study was to evaluate the long-term outcome of CESS in chronic rhinosinusitis (CRS) by measuring clinical and objective improvement, the need for revision surgery, and the complication rate.

Methods

We reviewed 114 patients with CRS with or without polyps who underwent CESS at our center between May 2006 and December 2011. CRS was assessed using the Lund-Mackay staging system. The follow-up period ranged from 18 to 84 months (May 2013).

Results

Of 114 patients, 83 presented CRS with nasal polyposis, 12 had CRS without nasal polyposis, 17 had Samter's triad, and 2 had antrochoanal polyps. Postoperative evaluation of nasal obstruction and olfaction showed a significant and lasting improvement in these symptoms. Only four patients (3.5%) have required revision surgery, to date.

Conclusion

CESS provided a lasting improvement in patients with CRS, by dramatically reducing the number of reinterventions. This approach is especially indicated in difficult cases, such as recurrent nasal polyposis and massive polyposis, because the dissection is based on constant borders and not influenced by previous surgery or disease extension.
Evaluating Humanitarian Action in Real Time: Recent Practices, Challenges, and Innovations
Authors: Polastro Riccardo
Published: May 2014

Abstract: Real-time evaluations (RTEs) are formative, utilization-focused evaluations that provide immediate feedback. Within the humanitarian system, RTEs are an innovation for improved learning and accountability today. In fluid and fast-changing environments they bridge the gap between conventional monitoring and evaluation, and influence policy and operational decision-making in a timely fashion. RTEs identify and propose solutions to operational and organizational problems in the midst of major humanitarian responses. The article (a) defines RTEs and situates them in the wider evaluation landscape; (b) examines RTEs’ use and users; (c) focuses on current methodological approaches; (d) looks into challenges, opportunities, and limitations that condition uptake; and (e) draws lessons and recommendations.
Assessing the Quality of Aboriginal Program Evaluations
Authors: Jacob Steve , Desautels Geoffroy
Published: May 2014

Abstract: Evaluations have gained in popularity in Canada since the 1990s, but statistical data indicate that the resources allocated to this management tool have not increased accordingly, despite the increased demand. During the same period, regardless of significant efforts to optimize governance, the Canadian federal government's management of issues related to Aboriginal peoples presents some weaknesses. Because evaluation may directly affect the administration of public programs, this study proposes a meta-evaluation of First Nations program evaluations. To do so, we replicate a methodology previously used by the Treasury Board Secretariat in 2004 to complete a vast study assessing the quality of evaluation in Canada. This article, based on the systematic analysis of a nonprobability sampling of more than 20 program evaluation reports, has applied the TBS's meta-evaluation techniques to the Aboriginal context. The results show that the evaluation of Aboriginal programs is of good, and even excellent, quality and suggest that the TBS's evaluation policy has had a definitive impact on evaluation quality.
The Effect of Borax on the Friction Performance of an Automotive Brake Lining
Authors: Sugozu Ilker , Can Ibrahim , Onerc Cengiz
Published: May 2014

In this study the effect of refined boron product borax on friction and wear performance of various brake friction couples were investigated. Different amounts of borax were used in the mix with other regular ingredients in the respective brake pad. Newly formulated brake pad material with nine different ingredients was tested using friction assessment and screening test (FAST). Among such specimens, only half of the samples (shown with H indices) were heat treated for 4 h at 180 °C. The friction coefficient as well as the wear rate were determined and the friction surfaces were examined by scanning electron microscope (SEM) to assess the performance of these samples. The heat treated sample that was reinforced with 12 % borax exhibited the optimum friction and wear behaviour. With increasing friction surface temperature, a reduction of the friction coefficient of the samples was observed. The lowest reduction of the friction coefficient was observed the 8 % and 12 % borax reinforced and heat treated samples.
Prediction of Surface Roughness in Longitudinal Turning Process by a Genetic Learning Algorithm
Authors: Aldaş Kemal , Özkul İskender , Eskil Murat
Published: May 2014

The surface roughness is one of the major parameters for determining the level of machining quality. The cutting parameters and conditions have great importance to achieve the desired values during the turning process. In the present work, a new approach was considered for modelling the effect of various turning process parameters and conditions on surface roughness. The experimental studies about the surface roughness after the turning process documented in the literature were collected and compiled into a model based on a genetic learning algorithm. As input parameters for modeling the work piece alloy type, tool type, tool tip radius, tool coating type, cooling conditions, cutting speed, feed rate, and cut depth were used in the study and were comprehensivly compiled.
Detection of defects in metallic specimens supported by ultrasound propagation simulations
Authors: Rodriguez Cristina , Fernández Mónica , Domíngue Javier , Biezma M. Victoria
Published: May 2014

The main aim of non-destructive testing (NDT) with ultrasounds (US) is the materials defect detection with respect to their main data, i. e. size, shape, and position. Inspectors carry out this task by attention to the reflected signal in the material and by comparison of the signals obtained at a specific defect with those of the defect-free material. In this way, the existence or absence of heterogeneities to be attributed to a specific defect can be determined. Inspectors are trained using specimens of the same material in which artificial defects are created, in order to establish a hypothetical appearance as natural defects. Such to be tested material specimens can be really expensive, and the total cost is particularly increased by the defect incorporation with the main scope to create the ideal size defects. The main purpose of this study is the detection of defects in metallic specimens by simulation of ultrasonic propagation in order to reduce the high cost of ultrasound protocol tests by comparing simulated and experimental results. It turned out that the good correlation between both methods allows using ultrasonic simulation as training method.
Structure Optimization of the 2D Angular Rotation of a Micro/Nano Table Using the Interface between Matlab and ANSYS
Authors: Helal Mahmoud , Rong Weibin , Wang Lefeng , Helal Waseem
Published: May 2014

Research and development of nano/micro-sized objects and systems have received considerable interest in the last few decades and were accelerated in the last decade due to the emergence of nanotechnology. Compliant mechanisms have made an enormous contribution in the design process of various fields such as for adaptive structures, hand-held tools, components in transportations, electronics, and surgical tools, respectively. The use of compliant mechanisms will help reducing the number of components, which therefore decrease manufacturing cost and additionally increase the performance. Topology optimization has proven to be a powerful method for the conceptual design of structures and mechanisms. Topology optimization is the technique that finds the optimal layout of the structure within a specified design domain. This paper presents the angular compliant mechanism of a micro/nano table which can realize a planer angular movement of the objects. The topology optimization is applied for designing two-dimensional micro/nano table angular compliant mechanism. The optimization algorithm is implemented using interface between Matlab and ANSYS. The final optimal topology configuration of the micro/nano angular table is shown and discussed.
Investigation of the mechanochemical behavior of the Mg – TiO2 – H3BO3 system
Authors: Torabi Omid , Golabgir Mohammad Hossein , Tajizadegan Hamid , Naghibi Sanaz , Jamshidi Amin
Published: May 2014

MgO – TiB2 nanocomposite was synthesized using mixtures of TiO2, H3BO3 and Mg as raw materials via a mechanochemical process. The phase transformation and structural evaluation were investigated by means of X-ray diffractometry, scanning electron microscopy, transmission electron microscopy and differential thermal analysis techniques. Thermodynamics evaluations indicated the reaction was highly exothermic and should be a mechanically induced self-sustaining reaction. According to X-ray analysis, MgO – TiB2 nanocomposite was formed after 4 h of ball milling. Thermal analysis results revealed that after 3 h milling, the temperature of combustion reaction decreased and all the reactions happened simultaneously. Scanning and transmission electron microscopy observations confirmed the range of particle size was within 100 nm.
Structural Development and Properties of Melt Spun Poly(butylene succinate) and Poly(butylene terephthalate-co-succinate-co-adipate) Biodegradable Fibers
Authors: Shi X. Q. , Takasaki M. , Ito H. , Kikutani T.
Published: May 2014

High-speed melt spinning of biodegradable aliphatic polyester poly(butylene succinate) (PBS), and aliphatic-aromatic copolyester poly(butylene terephthalate-co-succinate-co-adipate) (PBTSA) was carried out. The effects of spinning conditions on the structural development of PBS and PBTSA fibers were investigated through the measurements on on-line velocity profile, birefringence, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry, and tensile test. Both PBS and PBTSA fibers showed well-developed crystal structure in WAXD patterns, though the deformation of the spinline continued down to the position of winding suggesting that substantial orientation induced crystallization did not occur in spinline of both cases. Increasing take-up velocity or decreasing extrusion temperature led to the enhancement of molecular orientation, crystal structure and mechanical property of both PBS and PBTSA fibers, but no distinct effect on the thermal property of those fibers. The melting temperature of PBTSA fibers was at ca.115°C, same as that of PBS fibers. Elastomeric property of hard-soft units consisting PBTSA fibers leads to its good recoverability; however, this behavior lowers the initial modulus and tensile strength compared with those of the corresponding aliphatic PBS fibers.
Melt Compounding of Polymeric Nanocomposites
Authors: Utracki L. A. , Sepehr M. , Li J.
Published: May 2014

The clay-containing polymeric nanocomposites (CPNC) can be visualized as binary mixtures of strongly interacting, inorganic, plate-like molecules dispersed in a polymeric matrix. To be successful, one must ascertain the thermodynamics, which controls CPNC structure on the molecular level. In this work dispersion of organoclay (Cloisite 15A, C15A) in polyamide 6 (PA6) or in polypropylene (PP) is discussed. The PA-based CPNC's contained two components: polymer and organoclay, whereas those based on PP in addition contained a mixture of two maleated polypropylene's (PP-MA), as a compatibilizer. The melt compounding was carried out either in a single-screw extruder (SSE), or a twin-screw extruder (TSE). Both compounding lines were used with or without the extensional flow mixer (EFM). Furthermore, two versions of EFM were evaluated – one commercial, designed for polymer homogenization and blending, and the other designed for dispersing nano-particles. It was found that addition of EFM significantly improved clay dispersion. Better dispersion was found compounding the CPNC's in a SSE+EFM than in TSE with or without EFM. The best results were obtained using SSE with the new EFM having a relatively small gap between the convergent-divergent plates. C15A was fully exfoliated in PA6 matrix. The results in PP/PP-MA matrix were less spectacular, but again the highest degree of dispersion was obtained using SSE+new EFM with a small gap. Tensile, flexural and impact properties were measured and evaluated.
STAT-1 expression is regulated by IGFBP-3 in malignant glioma cells and is a strong predictor of poor survival in patients with glioblastoma
Authors: Thota Balaram , Arimappamagan Arivazhagan , Kandavel Thennarasu , Shastry Arun H. , Pandey Paritosh , Chandramouli Bangalore Ashwathnarayanarao , Hegde Alangar Sathyaranjandas , Kondaiah Paturu , Santosh Vani
Published: May 2014

Object

Insulin-like growth factor binding proteins (IGFBPs) have been implicated in the pathogenesis of glioma. In a previous study the authors demonstrated that IGFBP-3 is a novel glioblastoma biomarker associated with poor survival. Since signal transducer and activator of transcription 1 (STAT-1) has been shown to be regulated by IGFBP-3 during chondrogenesis and is a prosurvival and radioresistant molecule in different tumors, the aim in the present study was to explore the functional significance of IGFBP-3 in malignant glioma cells, to determine if STAT-1 is indeed regulated by IGFBP-3, and to study the potential of STAT-1 as a biomarker in glioblastoma.

Methods

The functional significance of IGFBP-3 was investigated using the short hairpin (sh)RNA gene knockdown approach on U251MG cells. STAT-1 regulation by IGFBP-3 was tested on U251MG and U87MG cells by shRNA gene knockdown and exogenous treatment with recombinant IGFBP-3 protein. Subsequently, the expression of STAT-1 was analyzed with real-time reverse transcription–polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC) in glioblastoma and control brain tissues. Survival analyses were done on a uniformly treated prospective cohort of adults with newly diagnosed glioblastoma (136 patients) using Kaplan-Meier and Cox regression models.

Results

IGFBP-3 knockdown significantly impaired proliferation, motility, migration, and invasive capacity of U251MG cells in vitro (p < 0.005). Exogenous overexpression of IGFBP-3 in U251MG and U87MG cells demonstrated STAT-1 regulation. The mean transcript levels (by real-time RT-PCR) and the mean labeling index of STAT-1 (by IHC) were significantly higher in glioblastoma than in control brain tissues (p = 0.0239 and p < 0.001, respectively). Multivariate survival analysis revealed that STAT-1 protein expression (HR 1.015, p = 0.033, 95% CI 1.001–1.029) along with patient age (HR 1.025, p = 0.005, 95% CI 1.008–1.042) were significant predictors of shorter survival in patients with glioblastoma.

Conclusions

IGFBP-3 influences tumor cell proliferation, migration, and invasion and regulates STAT-1 expression in malignant glioma cells. STAT-1 is overexpressed in human glioblastoma tissues and emerges as a novel prognostic biomarker.
Gamma Knife surgery for arteriovenous malformations within or adjacent to the ventricles
Authors: Bowden Greg , Kano Hideyuki , Yang Huai-che , Niranjan Ajay , Flickinger John , Lunsford L. Dade
Published: May 2014

Object

The outcomes of stereotactic radiosurgery for arteriovenous malformations (AVMs) within or adjacent to the ventricular system are largely unknown. This study assessed the long-term outcomes and hemorrhage risks for patients with AVMs within this region who underwent Gamma Knife surgery (GKS) at the University of Pittsburgh.

Methods

The authors retrospectively identified 188 patients with ventricular-region AVMs who underwent a single-stage GKS procedure during a 22-year interval. The median patient age was 32 years (range 3–80 years), the median target volume was 4.6 cm3 (range 0.1–22 cm3), and the median marginal dose was 20 Gy (range 13–27 Gy).

Results

Arteriovenous malformation obliteration was confirmed by MRI or angiography in 89 patients during a median follow-up of 65 months (range 2–265 months). The actuarial rates of total obliteration were 32% at 3 years, 55% at 4 years, 60% at 5 years, and 64% at 10 years. Higher rates of AVM obliteration were obtained in the 26 patients with intraventricular AVMs. Twenty-five patients (13%) sustained a hemorrhage during the initial latency interval after GKS, indicating an annual hemorrhage rate of 3.4% prior to AVM obliteration. No patient experienced a hemorrhage after AVM obliteration was confirmed by imaging. Permanent neurological deficits due to adverse radiation effects developed in 7 patients (4%).

Conclusions

Although patients in this study demonstrated an elevated hemorrhage risk that remained until complete obliteration, GKS still proved to be a generally safe and effective treatment for patients with these high-risk intraventricular and periventriclar AVMs.
Predictors of the need for cerebrospinal fluid diversion in patients with myelomeningocele
Authors: Phillips Blake C. , Gelsomino Michael , Pownall Ambre' L. , Ocal Eylem , Spencer Horace J. , O'Brien Mark S. , Albert Gregory W.
Published: May 2014

Object

Many patients with myelomeningocele (MMC) develop hydrocephalus, and most will undergo CSF diversion. The goal of this retrospective study was to determine whether there was a change in the shunt rate over the 7 consecutive years of the study. The authors will also identify the criteria used to determine the need for shunt placement.

Methods

During a 7-year period, 73 patients underwent MMC closure at Arkansas Children's Hospital. The shunt rate for each year was calculated. Clinical characteristics were evaluated, including apneic and bradycardic spells, CSF leak, level of the MMC, head circumference, and rate of head growth. In addition, radiological images were reviewed, and the frontooccipital horn ratio (FOHR), ventricular index (VI), and thalamooccipital distance (TOD) were calculated. Comparisons were made between those patients who underwent shunt placement and those who did not.

Results

One patient was excluded due to death in the perinatal period. Of the 72 remaining patients, 54 (75%) underwent placement of a ventriculoperitoneal shunt. This rate did not change significantly over time. Between the cohorts with and without a shunt there was no significant difference in age, sex, or race. There was no significant difference in apneic episodes or bradycardic episodes. There was a statistically significant difference in fontanelle characteristics, head circumference at birth, and rate of head growth. Patients who required CSF diversion had a mean head growth of 0.32 cm/day compared with those who did not receive a shunt (0.13 cm/day; p < 0.05). All radiological parameters were found to be statistically significant.

Conclusions

In this study, several classic indicators of hydrocephalus in the neonate were not found to be significantly associated with the need for CSF diversion. Fontanelle characteristics, head circumference at birth, and head growth velocity were associated with the need for shunt placement. Imaging information including the VI, TOD, and FOHR are statistically significant measures to evaluate prior to placement of a ventriculoperitoneal shunt. The optimal patient with MMC for CSF diversion will have full to tense fontanelle, increasing head circumference of more than 3 mm/day, and radiological evidence of an elevated VI, TOD, and/or FOHR.
Ganglioneuroblastoma of filum terminale
Authors: Okudera Yoshihiko , Miyakoshi Naohisa , Sugawara Taku , Hongo Michio , Kasukawa Yuji , Ishikawa Yoshinori , Shimada Yoichi
Published: May 2014

Object

Neuroblastic tumors can be classified as neuroblastoma, ganglioneuroblastoma (GNB), or ganglioneuroma. Ganglioneuroblastomas consist of small, round, immature neuroblast cells and matured ganglion cells. They are most commonly found in the mediastinum and retroperitoneum; intraspinal GNBs are extremely rare. There are only 5 cases of intraspinal GNB reported in the English literature. The authors report a case of GNB of the filum terminale. The duration of follow-up after the initial treatment is longer than in any other published reports.

Methods

A 36-year-old woman underwent resection of an intradural extramedullary tumor at L1–2 in 1993. Pathological diagnosis was GNB. After surgery, her symptoms resolved and she recovered to a normal condition. In 2009, when she was 53 years old, she presented to the hospital with paralysis of both legs. Magnetic resonance imaging suggested recurrence of spinal tumor. She underwent subtotal resection of the tumors, followed by 4 weeks of radiation therapy.

Results

Neurological symptoms improved, and, after radiation therapy, the patient was able to walk with a crutch. Histological investigation of the excised tumor indicated that it was a nodular type GNB, which was consistent with the diagnosis from the time of the initial surgery in 1993. Follow-up MRI studies showed no growth of residual tumors in the 3 years following the surgery.

Conclusions

The authors present a rare case of spinal GNB. The duration of follow-up after the initial surgery in 1993 represents the longest description of clinical course after treatment for spinal GNB.