bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparative study of different machine learning methods on microarray gene expression data
Authors: Pirooznia Mehdi , Yang Jack Y , Yang Mary Qu , Deng Youping
Published: March 2008

Background

Several classification and feature selection methods have been studied for the identification of differentially expressed genes in microarray data. Classification methods such as SVM, RBF Neural Nets, MLP Neural Nets, Bayesian, Decision Tree and Random Forrest methods have been used in recent studies. The accuracy of these methods has been calculated with validation methods such as v-fold validation. However there is lack of comparison between these methods to find a better framework for classification, clustering and analysis of microarray gene expression results.

Results

In this study, we compared the efficiency of the classification methods including; SVM, RBF Neural Nets, MLP Neural Nets, Bayesian, Decision Tree and Random Forrest methods. The v-fold cross validation was used to calculate the accuracy of the classifiers. Some of the common clustering methods including K-means, DBC, and EM clustering were applied to the datasets and the efficiency of these methods have been analysed. Further the efficiency of the feature selection methods including support vector machine recursive feature elimination (SVM-RFE), Chi Squared, and CSF were compared. In each case these methods were applied to eight different binary (two class) microarray datasets. We evaluated the class prediction efficiency of each gene list in training and test cross-validation using supervised classifiers.

Conclusions

We presented a study in which we compared some of the common used classification, clustering, and feature selection methods. We applied these methods to eight publicly available datasets, and compared how these methods performed in class prediction of test datasets. We reported that the choice of feature selection methods, the number of genes in the gene list, the number of cases (samples) substantially influence classification success. Based on features chosen by these methods, error rates and accuracy of several classification algorithms were obtained. Results revealed the importance of feature selection in accurately classifying new samples and how an integrated feature selection and classification algorithm is performing and is capable of identifying significant genes.
Supervised learning-based tagSNP selection for genome-wide disease classifications
Authors: Liu Qingzhong , Yang Jack , Chen Zhongxue , Yang Mary Qu , Sung Andrew H , Huang Xudong
Published: March 2008

Background

Comprehensive evaluation of common genetic variations through association of single nucleotide polymorphisms (SNPs) with complex human diseases on the genome-wide scale is an active area in human genome research. One of the fundamental questions in a SNP-disease association study is to find an optimal subset of SNPs with predicting power for disease status. To find that subset while reducing study burden in terms of time and costs, one can potentially reconcile information redundancy from associations between SNP markers.

Results

We have developed a feature selection method named Supervised Recursive Feature Addition (SRFA). This method combines supervised learning and statistical measures for the chosen candidate features/SNPs to reconcile the redundancy information and, in doing so, improve the classification performance in association studies. Additionally, we have proposed a Support Vector based Recursive Feature Addition (SVRFA) scheme in SNP-disease association analysis.

Conclusions

We have proposed using SRFA with different statistical learning classifiers and SVRFA for both SNP selection and disease classification and then applying them to two complex disease data sets. In general, our approaches outperform the well-known feature selection method of Support Vector Machine Recursive Feature Elimination and logic regression-based SNP selection for disease classification in genetic association studies. Our study further indicates that both genetic and environmental variables should be taken into account when doing disease predictions and classifications for the most complex human diseases that have gene-environment interactions.
Up-regulation of multiple proteins and biological processes during maxillary expansion in rats
Authors: Ma Junqing , Wu Yunxia , Zhang Weibing , Smales Roger J , Huang You , Pan Yongchu , Wang Lin
Published: March 2008

Background

Maxillary expansion (ME) is a common practice in orthodontics that aims to increase the constricted maxillary arch width. Relapse often occurs, however, and better treatment strategies are needed. In order to develop a more effective method, this study was designed to further examine the process of tissue remodeling during ME, to identify the changes in expression of several proteins of interest, and to clarify the molecular mechanism responsible for tissue remodeling.

Methods

Male Wistar rats were randomly divided into control and ME groups. The rats were euthanized at various intervals over 11 days, and the dissected palates were prepared for histological examination. The structure of the midpalatal sutures changed little during the first three days. Proteins from samples in the ground midpalatal tissues obtained on the third day were subjected to two-dimensional polyacrylamide gel electrophoresis (2-DE) and matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis. Validation of protein expression was performed by Western blot analyses.

Results

From day 5, chondrocytes in the inner layer of suture cartilage and osteoblasts at the end of the suture cartilage began to proliferate, and the skeletal matrix increased later adjacent to the cartilage in the ME group. Comparative proteomic analysis showed increases in 22 protein spots present in the ME group. The changes in three proteins closely related to osteogenesis (parathyroid hormone, osteoprotegerin and vimentin) were confirmed by Western blotting.

Conclusion

Many proteins are over-expressed during ME, and they may play an important role in the remodeling process.
Early and transient reverse transcription during primary deltaretroviral infection of sheep
Authors: Pomier Carole , Alcaraz Maria T Sanchez , Debacq Christophe , Lançon Agnes , Kerkhofs Pierre , Willems Lucas , Wattel Eric , Mortreux Franck
Published: March 2008

Background

Intraindividual genetic variability plays a central role in deltaretrovirus replication and associated leukemogenesis in animals as in humans. To date, the replication of these viruses has only been investigated during the chronic phase of the infection when they mainly spread through the clonal expansion of their host cells, vary through a somatic mutation process without evidence for reverse transcriptase (RT)-associated substitution. Primary infection of a new organism necessary involves allogenic cell infection and thus reverse transcription.

Results

Here we demonstrate that the primary experimental bovine leukemia virus (BLV) infection of sheep displays an early and intense burst of horizontal replicative dissemination of the virus generating frequent RT-associated substitutions that account for 69% of the in vivo BLV genetic variability during the first 8 months of the infection. During this period, evidence has been found of a cell-to-cell passage of a mutated sequence and of a sequence having undergone both RT-associated and somatic mutations. The detection of RT-dependent proviral substitution was restricted to a narrow window encompassing the first 250 days following seroconversion.

Conclusion

In contrast to lentiviruses, deltaretroviruses display two time-dependent mechanisms of genetic variation that parallel their two-step nature of replication in vivo. We propose that the early and transient RT-based horizontal replication helps the virus escape the first wave of host immune response whereas somatic-dependent genetic variability during persistent clonal expansion helps infected clones escape the persistent and intense immune pressure that characterizes the chronic phase of deltaretrovirus infection.
Aqueous extracts from peppermint, sage and lemon balm leaves display potent anti-HIV-1 activity by increasing the virion density
Authors: Geuenich Silvia , Goffinet Christine , Venzke Stephanie , Nolkemper Silke , Baumann Ingo , Plinkert Peter , Reichling Jürgen , Keppler Oliver T
Published: March 2008

Background

Aqueous extracts from leaves of well known species of the Lamiaceae family were examined for their potency to inhibit infection by human immunodeficiency virus type 1 (HIV-1).

Results

Extracts from lemon balm (Melissa officinalis L.), peppermint (Mentha × piperita L.), and sage (Salvia officinalis L.) exhibited a high and concentration-dependent activity against the infection of HIV-1 in T-cell lines, primary macrophages, and in ex vivo tonsil histocultures with 50% inhibitory concentrations as low as 0.004%. The aqueous Lamiaceae extracts did not or only at very high concentrations interfere with cell viability. Mechanistically, extract exposure of free virions potently and rapidly inhibited infection, while exposure of surface-bound virions or target cells alone had virtually no antiviral effect. In line with this observation, a virion-fusion assay demonstrated that HIV-1 entry was drastically impaired following treatment of particles with Lamiaceae extracts, and the magnitude of this effect at the early stage of infection correlated with the inhibitory potency on HIV-1 replication. Extracts were active against virions carrying diverse envelopes (X4 and R5 HIV-1, vesicular stomatitis virus, ecotropic murine leukemia virus), but not against a non-enveloped adenovirus. Following exposure to Lamiaceae extracts, the stability of virions as well as virion-associated levels of envelope glycoprotein and processed Gag protein were unaffected, while, surprisingly, sucrose-density equilibrium gradient analyses disclosed a marked increase of virion density.

Conclusion

Aqueous extracts from Lamiaceae can drastically and rapidly reduce the infectivity of HIV-1 virions at non-cytotoxic concentrations. An extract-induced enhancement of the virion's density prior to its surface engagement appears to be the most likely mode of action. By harbouring also a strong activity against herpes simplex virus type 2, these extracts may provide a basis for the development of novel virucidal topical microbicides.
The role of chloride anion and CFTR in killing ofPseudomonas aeruginosaby normal and CF neutrophils
Authors: Painter Richard G , Bonvillain Ryan W , Valentine Vincent G , Lombard Gisele A , LaPlace Stephanie G , Nauseef William M , Wang Guoshun
Published: March 2008

Chloride anion is essential for myeloperoxidase (MPO) to produce hypochlorous acid (HOCl) in polymorphonuclear neutrophils (PMNs). To define whether chloride availability to PMNs affects their HOCl production and microbicidal capacity, we examined how extracellular chloride concentration affects killing of Pseudomonas aeruginosa (PsA) by normal neutrophils. PMN-mediated bacterial killing was strongly dependent on extracellular chloride concentration. Neutrophils in a chloride-deficient medium killed PsA poorly. However, as the chloride level was raised, the killing efficiency increased in a dose-dependent manner. By using specific inhibitors to selectively block NADPH oxidase, MPO, and cystic fibrosis transmembrane conductance regulator (CFTR) functions, neutrophil-mediated killing of PsA could be attributed to three distinct mechanisms: CFTR-dependent and oxidant-dependent; chloride-dependent but not CFTR- and oxidant-dependent; and independent of any of the tested factors. Therefore, chloride anion is involved in oxidant- and nonoxidant-mediated bacterial killing. We previously reported that neutrophils from CF patients are defective in chlorination of ingested bacteria [1], suggesting that the chloride channel defect might impair the MPO-hydrogen peroxide-chloride microbicidal function. Here, we compared the competence of killing PsA by neutrophils from normal donors and CF patients. The data demonstrate that the killing rate by CF neutrophils was significantly lower than that by normal neutrophils. CF neutrophils in a chloride-deficient environment had only one-third of the bactericidal capacity of normal neutrophils in a physiological chloride environment. These results suggest that CFTR-dependent chloride anion transport contributes significantly to killing PsA by normal neutrophils and when defective as in CF, may compromise the ability to clear PsA.
A dual role of activin A in regulating immunoglobulin production of B cells
Authors: Ogawa Kenji , Funaba Masayuki , Tsujimoto Masafumi
Published: March 2008

Here, we report that activin A has a dual role in regulating Ig production of murine B cells. Activated B cells secrete activin activity by increasing activin A and decreasing follistatin expression. B cells also express type I and type II activin receptors, suggesting that they are targets of activin. Pretreatment of naïve B cells with activin A and subsequent activation by LPS resulted in increased cell growth and IgG production. In contrast, no significant effect was observed when activin A was added to naïve B cells simultaneously with LPS, indicating that activin A acts on resting but not activated B cells. In addition, activin A did not induce B cells to produce IgE, even when added prior to activation; however, in vivo antigen-specific IgE production was reduced significantly by neutralization of circulating activin A. These findings indicate that activin A plays an important role in Th2-mediated immune responses by enhancing antibody production through two distinct modes: acts directly on resting B cells to elicit full functions of activated B cells and acts indirectly on activated B cells through modulation of other immune cells.
Diminishing HDACs by drugs or mutations promotes normal or abnormal sister chromatid separation by affecting APC/C and adherin
Authors: Kimata Yuu , Matsuyama Akihisa , Nagao Koji , Furuya Kanji , Obuse Chikashi , Yoshida Minoru , Yanagida Mitsuhiro
Published: March 2008

Histone acetyltransferases (HATs) and histone deacetylases (HDACs) play important roles in cell regulation, including cell cycle progression, although their precise role in mitotic progression remains elusive. To address this issue, the effects of HDAC inhibition were examined upon a variety of mitotic mutants of the fission yeast Schizosaccharomyces pombe, which contains three HDACs that are sensitive to trichostatin A (TSA) and are similar to human HDACs. Here it is shown that HDACs are implicated in sister chromatid cohesion and separation. A mutant of the cohesin loader Mis4 (adherin) was hypersensitive to TSA and synthetically lethal with HDAC deletion mutations. TSA treatment of mis4 mutant cells decreased chromatin-bound cohesins in the chromosome arm region. By contrast, HDAC inhibitors and clr6 HDAC mutations rescued temperature sensitive (ts) phenotypes of the mutants of the ubiquitin ligase complex anaphase-promoting complex/cyclosome (APC/C), which display metaphase arrest. This suppression coincided with facilitated complex formation of APC/C. Moreover, our mass spectrometry analysis showed that an APC/C subunit, Cut23/APC8, is acetylated. HATs and HDACs might directly target adherin and APC/C to ensure proper chromosome segregation, and anti-tumour effects of HDAC inhibitors could be attributed to this deregulation.
Cell-cycle-specific nestin expression coordinates with morphological changes in embryonic cortical neural progenitors
Authors: Sunabori Takehiko , Tokunaga Akinori , Nagai Takeharu , Sawamoto Kazunobu , Okabe Masaru , Miyawaki Atsushi , Matsuzaki Yumi , Miyata Takaki , Okano Hideyuki
Published: March 2008

During brain development, neural progenitor cells extend across the thickening brain wall and undergo mitosis. To understand how these two completely different cellular events are coordinated, we focused on the transcription pattern of the nestin gene (Nes), which encodes an intermediate filament protein strongly expressed in neural progenitor cells. To visualize nestin expression in vivo, we generated transgenic mice that expressed a destabilized fluorescent protein under the control of Nes second intronic enhancer (E/nestin:dVenus). During the neurogenic stage, when the brain wall thickens markedly, we found that nestin was regulated in a cell-cycle-dependent manner. Time-lapse imaging showed that nestin gene expression was upregulated during G1-S phase, when the neural progenitor cells elongate their fibers. However, nestin expression dramatically declined in G2-M phase, when progenitor cells round up to undergo mitosis. The cell-cycle-dependent phosphorylation of an upstream regulator class III POU transcription factor (Pou3f2 or Brn2) reduced its binding activity to the nestin core enhancer element and was therefore responsible for the decreased Nes transcription in G2-M phase. Collectively, these findings demonstrate precisely orchestrated gene regulation that correlates with the 3D morphological changes in neural progenitor cells in vivo.
An enhanced methodical approach to machine tool design procedure
Authors: Nategh M J , Tabatabaie S E
Published: March 2008

The designers' heuristic approach has been the subject of research, with a view to developing algorithms that can be used in automated design systems. However, apart from some general achievements, viable results are not sufficiently available to be employed in machine tool design procedures. The existing algorithms suffer serious deficiencies, restraining their viable use. In pursuit of a total solution, the current authors have proposed an enhanced methodology on the basis of a weighted priority system that can be used for various steps of machine tool design practice and competitiveness evaluation procedure. The core idea of this methodology is based on prioritization of design factors. The weighted priority orders of input information and the degree and intensity of connectivity existing between input information and design factors are used to decide the priorities of design factors. This methodical approach can assist in developing consistency among the designers throughout design procedures, improving competence of young engineers, and developing total solutions and CAD programs. Its applications have been illustrated by examples of layout, assembly, and component design for machining centres and lathes.
Electric discharge milling of insulating ceramics
Authors: Liu Y H , Ji R J , Li X P , Yu L L , Zhang H F
Published: March 2008

Ceramics have been used widely in modern industry. However, the manufacture of ceramic blanks is not an efficient process. The shaping of ceramic blanks with conventional machining methods (such as grinding) is a long, labour-intensive, and costly process. Electromachining processes promise to be effective and economical techniques for the production of tools and parts from ceramic blanks. Wire electric discharge machining (WEDM) is able to slice ceramics effectively. Electrical discharge machining (EDM) and electrical discharge grinding (EDG) shape ceramic blanks at a lower cost. With the help of some assisting methods, WEDM, EDM, and EDG can be used to machine insulating ceramics. However, WEDM, EDM, and EDG of insulating ceramics show lower efficiency, especially for a large surface area on insulating ceramics. This paper presents a new process of machining insulating ceramics using electrical discharge (ED) milling. ED milling uses a thin copper sheet fed to the tool electrode along the surface of the workpiece as the assisting electrode, and uses a water-based emulsion as the machining fluid. This process is able effectively to machine a large surface area on insulating ceramics, as well as other advanced non-conductive materials such as cubic born nitride (CBN) and polycrystalline diamond (PCD). The machining principle and characteristics of the technique are introduced. The effect of pulse on-time, pulse off-time, and peak current on the process performance has been investigated.
Exhaust emission characteristics of a low-heat-rejection diesel engine fuelled with 10 per cent ethanol and 90 per cent diesel fuel mixture
Authors: Hasimoglu C
Published: March 2008

Simultaneously reducing smoke and nitrogen oxide (NO x) emissions of diesel engines is an important problem in exhaust emission control. Use of ethanol—diesel fuel blend may be an alternative way to reduce both these emissions at the same time without modification of any engine-operating parameters. In this study the effect of an ethanol—diesel fuel blend on the simultaneous reduction in smoke and NO x emissions in a direct-injection turbocharged diesel engine with low-heat-rejection application was investigated. For this purpose, ethanol (10 vol/%) diesel fuel blend was used as the fuel, and the cylinder head, valves, and pistons of the test engine were coated with a yttria stabilized zirconia (Y2O3—ZrO2) layer 0.35 mm thick over a nickel-chromium—aluminium bond coat 0.15 mm thick by the atmospheric plasma spray coating method. The results of the engine tests have shown that, with ethanol addition, the NO x emission was decreased by 71.3 per cent at 1200 r/min and by 40.7 per cent at 2200 r/min, the smoke emission was decreased by 39.8 per cent at 1200 r/min and by 20.3 per cent at 2200 r/min, the excess air ratio was increased by 43.9 per cent at 1200 r/min and decreased by 7.9 per cent at 2200 r/min, and the oxygen (O2) emission was increased by 27.3 per cent at 1200 r/min and decreased by 8.6 per cent at 2200 r/min, in comparison with the standard engine.
Model-based detection and isolation of faults due to ageing in the air and fuel paths of common-rail direct injection diesel engines equipped with a λ and a nitrogen oxides sensor
Authors: Schilling A , Amstutz A , Guzzella L
Published: March 2008

The air and fuel management of modern diesel engines is based on a feedforward control approach. As a consequence, faults of the air or the fuel path have a direct impact on the emissions that cannot be observed nor compensated. Faults due to the ageing of engine parts are very common; thus engines are designed with tolerances large enough to fulfil the emission standards for their entire lifetime.

This paper presents a method to locate and quantify engine faults due to the ageing of parts of modern diesel engines in order to help to reduce design tolerances. A relative air-to-fuel ratio and a nitrogen oxides emission sensor have been applied to a test-bench engine, and control-oriented emission models have been developed. Based thereon, a model-based fault detection and isolation system has been implemented. The sensor signals are compared with the models in order to detect a possible fault, and fault location and size are estimated by means of a bank of extended Kalman filters, one for each fault considered. Results from the New European Driving Cycle show that the developed control-oriented models are accurate, and the faults can be correctly detected and isolated.
Analysis of the integration of knowledge and novelty in creative engineering design
Authors: Allen J E , Self A
Published: March 2008

The general creative process is incapable of strict analysis but for engineering it is correctly identified with the design function that combines knowledge, derived from science, technology, and past experience, with the novelty of an invention or development. Engineering achievements range from projects of vast scale, such as the elements of the NASA space programme, to minute devices of great ingenuity such as human joint replacements. As Professor Jones remarked in his 1974 paper to the IMechE, ‘Koestler's book ‘The Act of Creation’ did not mention engineering and the word creativity was not in the Oxford English Dictionary of 1973!′ The nature of creative thinking is chaotic and many significant breakthroughs seem to have arisen by accident. The current paper concentrates on the early stages of the evolution of a new engineering entity and studies the blending of rigorous scientific knowledge (materials, dynamics, systems etc.) with the much more ‘fuzzy’ process of taking the first concepts through the process of preliminary design to a viable product. The work makes a contribution to engineering education.

In seeking the heart of the creative engineering process examples are examined mainly from large-scale projects, as typically found in aerospace. This experience is compared briefly with civil, mechanical, and systems engineering to seek for differences and similarities in method and, in contrast with the modern ‘enterprise function’, i.e. the process from the inventor to a new business. The last of these is of considerable economic significance today.
Satellite multi-functional power structure: Feasibility and mass savings
Authors: Roberts S C , Aglietti G S
Published: March 2008

A multi-functional structure saves mass from a spacecraft by incorporating other functional subsystems into the structure. By using the structural properties of a non-structural element, inert structure may be eliminated, and the requirement to allot internal volume to the subsystem in question is removed.

The current paper describes a multi-functional structure based on the secondary power system. By using commercially available plastic lithium-ion cells to form the core of a sandwich panel, inert mass is eliminated from both the structure and from the battery enclosure. The feasibility of the proposed multi-functional structure is demonstrated though vibration testing on a single cell, and the successful manufacture of a test panel.

The work goes on to quantify the potential mass savings that may be achieved by using a multi-functional structure of this type. By varying a set of spacecraft attributes, the study identifies that small spacecraft with high power requirements have the potential to gain the most benefit from using a multi-functional structure of this type.
Effect of position and height of a mobile core type artificial disc on the biomechanical behaviour of the lumbar spine
Authors: Rohlmann A , Zander T , Bock B , Bergmann G
Published: March 2008

The extent of natural disc removal and the implant position and height of an artificial disc with a mobile core were studied for their effects on intersegmental rotation, intradiscal pressure, and facet joint force. A validated finite element model of the lumbar spine was used. The model was loaded with the upper body weight, a follower load, and muscle forces to simulate standing, flexion, extension, lateral bending, and axial rotation. The implant position was varied up to 2 mm in an anterior and posterior direction and up to 3 mm in a lateral direction. Three different implant heights were simulated. The effect of removing the lateral parts of the annulus was also studied. The implant position and height markedly affect intersegmental rotation and facet joint forces but have hardly any influence on intradiscal pressure in the adjacent discs.

Removing the lateral parts of the annulus increases intersegmental rotation and facet joint force mainly for lateral bending and axial rotation. The calculated translation of the mobile implant core is about 1 mm at most, and thus its effect is often overestimated. Great care should be taken to choose the optimal implant height and to insert the implant in the best position for each individual patient.
Particle attrition of α-tricalcium phosphate: Effect on mechanical, handling, and injectability properties of calcium phosphate cements
Authors: Jack V , Buchanan F J , Dunne N J
Published: March 2008

Calcium phosphate bone cements are currently used in a range of applications; however, their low compressive strength and brittle failure mechanics have limited their widespread application. The aim of this study was to improve the mechanical performance of the calcium phosphate cement by means of particle reduction of the powder components involved. α-tricalcium phosphate (α-TCP) powder was produced and subsequently reacted with water to form a calcium-deficient hydroxyapatite in the form of a biocompatible and resorbable cement. It was postulated that the reduction of the α-TCP particle size would result in a fastersetting reaction and stronger cement. Three milling techniques were explored and their methods optimized. The techniques included the traditional ball-milling technique and two newer techniques, namely cryogenic and planetary milling. Particle size analysis through laser diffraction and scanning electron microscopy was conducted. Compressive strength, setting times and injectability characteristics of the curing cement were determined.

It was observed that all three techniques were efficient methods of particle reduction and the mechanical, setting and injectability properties were significantly improved by the reduction in particle size of the α-TCP powder. However, agglomerations of α-tricalcium phosphate resulted in a reduction in compressive strength and injectability after prolonged milling periods, irrespective of milling technique.
Strain pattern following surface replacement of the hip
Authors: Ganapathi M , Evans S , Roberts P
Published: March 2008

The aim is to compare the strain pattern in intact and resurfaced femurs using validated third-generation composite femurs and rosette strain gauges. The rosette strain gauges were applied to an intact and a resurfaced third-generation composite femur at three sites: the narrowest part of the lateral surface of the neck, the narrowest part of the medial surface of the neck, and the medial surface at the level of the lesser trochanter. The maximum and minimum principal strains were calculated at axial loads of 600, 800, and 1000 N. Further tests were carried out with an additional abductor load. The maximum principal strains in the resurfaced femur were approximately 50 per cent higher in the lateral surface of the neck and about 25 per cent higher in the lesser trochanteric region than in the intact femur. Inclusion of the abductor force decreased the strains in both the intact and the resurfaced femurs, particularly at the lateral surface of the femoral neck. Increased strain at the lateral surface of the femoral neck following hip resurfacing could be a cause of neck fracture, particularly if there are other predisposing factors such as notching of the femoral neck and/or abductor dysfunction. Meticulous repair of the abductors is warranted if a lateral approach is used.
Smooth surface micro finite element modelling of a cancellous bone analogue material
Authors: Leung S Y , Browne M , New A M
Published: March 2008

Tetrahedral finite element meshes with smooth surfaces can be created from computed tomography scans of cancellous bone in order to evaluate its mechanical properties. Image processing before creation of the mesh can affect the accuracy of determined mechanical properties. For a cancellous bone analogue, threshold, mesh density and surface smoothing parameters used in mesh generation were varied and the mechanical properties predicted by the resulting meshes were compared to experimental results. This study has shown that threshold selection is vital for accurate determination of volume fraction and resulting mechanical properties.
Robust constrained predictive controllers for hot rolling mills: Disturbance uncertainty case
Authors: Choi I-S , Rossiter J A , Fleming P J
Published: March 2008

Looper—tension control among various control problems in hot rolling mills (HRMs) has significance, in particular, because it affects both operational stability of the process and dimensional quality of the products. The control target in this control loop is to maintain looper angle and strip tension simultaneously at their desired values. The most difficult challenge in the controller design arises from the interaction, between strip tension and looper angle, and uncertainty coming from disturbances and a model mismatch. Recently, there has been some research to investigate the potential benefits of model predictive control (MPC) for this control loop. However, most of them used constrained optimization based on nominal models, and this often caused constraint violations for the uncertain case. The purpose of this paper is to develop robust MPC algorithms for the hot rolling mill process, in the presence of disturbance uncertainty, in order to improve the constraint handling performance.
Effects of Hydrothermal Treatment and Template Removal on the Adsorption and Structural Properties of SBA-16 Mesoporous Silica
Authors: Fulvio Pasquale F. , Grabicka Bogna E. , Grudzien Rafal M. , Jaroniec Mietek
Published: March 2008

The evolution of the adsorption and structural properties of large-pore SBA-16 silica samples was studied in relation to hydrothermal treatment and template removal procedures. These samples were synthesized using the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer Pluronic F127 as the structure-directing agent and tetraethyl orthosilicate as the silica source in the presence of hydrochloric acid (low concentration) and sodium chloride under various hydrothermal treatment conditions. The concomitant use of the recently reported two-step template removal procedure, which combines solvent extraction and low-temperature calcination, afforded the SBA-16 samples with large pore volumes, high surface areas, uniform cages and uniform cage openings as demonstrated by nitrogen and argon adsorption isotherms measured at −196°C. Small-angle X-ray diffraction spectra confirmed the existence of the Im3m symmetry group (body-centred cubic pore structure) for the samples studied. The efficiency of the aforementioned template removal method was confirmed via thermogravimetric analysis.
Dimensioning Large-Scale Membership Services
Authors: de Véricourt Francis , Jennings Otis B.
Published: March 2008

Motivated by workforce planning problems in health care, professional, warranty, and repair services, we propose modeling service centers that are exclusively dedicated to fixed client constituencies as closed multiserver queueing systems, a framework we refer to as membership services. We provide fluid and diffusion approximations of the number of users within the membership who are requesting service. The approximations are obtained via many-server limit theorems, where the limiting regime assumptions of each theorem correspond to a particular staffing strategy a manager might employ. Accordingly, we propose staffing rules designed to meet a certain desired performance criterion. In particular, when the objective is to minimize the staffing size subject to a constraint on the probability of delay for a service-requesting customer, we suggest staffing rules inspired by the so-called quality- and efficiency-driven (QED), or Halfin-Whitt, limiting regime. Numerical evaluations of our proposed QED scheme indicate that, although justified for large systems, the staffing rule performs well for memberships of all sizes.
Successful Treatment of Vancomycin-Resistant Enterococcus Faecium Pyelonephritis with Daptomycin During Pregnancy
Authors: Shea Katherine , Hilburger Esther , Baroco Allison , Oldfield Edward
Published: March 2008

Objective:

To report successful treatment using daptomycin for pyelonephritis associated with van cornycin-resistant Enterococcus faecium (VRE) in a 27-week pregnant woman.

Case Summary:

A 20-year-old 27-week pregnant patient with a history of spina bifida, neurogenic bladder, and multiple hospitalizations for recurrent urinary tract infections (UTIs) was diagnosed with pyelonephritis. She was treated with daptomycin 260 mg (4 mg/kg) daily for 14 days on the basis of a urine culture that revealed E. faecium resistant to ampicillin, nitrofurantoin, and vancomycin. All cultures following treatment revealed no growth, and the patient as well as the neonate displayed no adverse effects.

Discussion:

VRE UTIs can be treated safely in pregnancy with nitrofurantoin, if the organism is susceptible. Other viable options in the treatment of VRE, including linezolid, doxycycline, and quinupristin/dalfopristin, have lower urinary concentrations, teratogenic risk, or limited findings regarding their safety in pregnancy. Daptomycin was selected in this case due to its efficacy in the treatment of VRE, high urinary concentrations, pregnancy category B, and one case report indicating its successful use in pregnancy.

Conclusions:

Treatment of VRE in pregnancy can be challenging due to the teratogenicity or unknown safety of available options. The use of daptomycin in our patient enabted a successful outcome of multidrug-resistant E. faecium in a complicated pregnant patient without observed neonatal abnormalities.
Moxifloxacin-Associated Neutropenia in a Cirrhotic Elderly Woman with Lower Extremity Cellulitis
Authors: Chang Chia-Ming , Lee Nan-Yao , Lee Hsin-Chun , Lee I-Wen , Wu Chi-Jung , Lin Yu-Shiuan , Ko Wen-Chien
Published: March 2008

OBJECTIVE:

To report a case of moxifloxacin-associated neutropenia in a cirrhotic patient with cellulitis.

CASE SUMMARY:

A 77-year-old cirrhotic woman developed cellulitis of the right leg, with a nadir white blood cell (WBC) count of 1.5 × 103/μL and absolute neutrophil count (ANC) of 0.345 × 103/μL, which occurred after 5 days of moxifloxacin therapy. Moxifloxacin was switched to cefixime and neutropenia resolved 2 days after the withdrawal of moxifloxacin.

DISCUSSION:

Cases of neutropenia related to fluoroquinolones have rarely been reported in the literature, and neutropenia associated with moxifloxacin has not been described before. Because of the temporal relationship between moxifloxacin administration and the development of neutropenia in our patient, as well as the relationship between drug withdrawal and improvement in WBC count and ANC, moxifloxacin-associated neutropenia was suspected. This reaction was categorized as probable according to the Naranjo probability scale.

CONCLUSIONS:

We report the first case of moxifloxacin-associated neutropenia. Although such an adverse reaction is rare, clinicians should be aware of this potential complication of moxifloxacin therapy.
Soil Stiffness Evaluation for Compaction Control of Cohesionless Embankments
Authors: Rahman Farhana , Hossain Mustaque , Hunt Morris M. , Romanoschi Stefan A.
Published: March 2008

Mechanistic pavement design procedures based on elastic layer theory require characterization of pavement layer materials including subgrade soil. This paper discusses the subgrade stiffness measurements obtained from a new compaction roller for compaction control on highway embankment projects in Kansas. Three test sections were compacted using a single, smooth steel drum intelligent compaction (IC) roller that compacts and simultaneously, measures stiffness values of the compacted soil. Traditional compaction control measurements such as, density, in-situ moisture content, stiffness measurements using a soil stiffness gage, surface deflection tests using the light falling weight deflectometer (LFWD) and falling weight deflectometer (FWD), and penetration tests using a dynamic cone penetrometer (DCP), were also done. The results show that the IC roller was able to identify the locations of lower soil stiffness in the spatial direction. Thus, an IC roller can be used in proof rolling. IC roller stiffness showed sensitivity to the field moisture content indicating that moisture control during compaction is critical. No universal correlation was observed among the IC roller stiffness, soil gage stiffness, back-calculated subgrade moduli from the LFWD and FWD deflection data, and the California bearing ratio obtained from DCP tests. The discrepancy seems to arise from the fact that different pieces of equipment were capturing response from different volumes of soil on the same test section.
Comparison of Averaging Procedures for Point Load Testing of Rock
Authors: Karaca Z. , Yilmaz N. Gunes , Goktan R. M.
Published: March 2008

This paper presents the experimental results of a laboratory point load testing program carried out to analyze the effect of two different point load mean value calculation procedures on the prediction accuracy of uniaxial compressive strength of rocks. Apart from the calculation procedure corresponding to the one suggested by ASTM and ISRM, a second calculation procedure involving the ordinary arithmetic mean value was used in the analyses. Axial point load tests were conducted on a total of 19 rocks having two different thickness-to-diameter ratios. Finally, the results of the point load tests were correlated with those of the standard uniaxial compressive strength tests, and some test statistics were employed to determine the relative effectiveness of the considered calculation procedures. Valid for axial testing method and the tested rock types, it was concluded that the suggested mean value calculation procedure by the ASTM and ISRM has no significant advantage compared with the traditional statistical procedure that involves ordinary arithmetic mean.
Applicability of the Fracture Toughness Master Curve to Irradiated Highly Embrittled Steel and Intergranular Fracture
Authors: Nanstad R. K. , Sokolov M. A. , McCabe D. E.
Published: March 2008

The Heavy-Section Steel Irradiation Program at Oak Ridge National Laboratory has evaluated a submerged-arc (SA) weld irradiated to a high level of embrittlement and a temper embrittled base metal that exhibits significant intergranular fracture relative to representation by the Master Curve. The temper embrittled steel revealed that the intergranular mechanism significantly extended the transition temperature range up to 150°C above To. For the irradiated highly embrittled SA weld study, a total of 21 1T compact specimens were tested at five different temperatures and showed the Master Curve to be nonconservative relative to the results, although that observation is uncertain due to evidence of intergranular fracture.
Investigation of a Developmental Model of Risk for Depression and Suicidality Following Spousal Bereavement
Authors: Johnson Jeffrey G. , Zhang Baohui , Prigerson Holly G.
Published: March 2008

Data from a community‐based multi‐wave investigation were used to examine a developmental model of risk for depression and suicidality following the death of a spouse. Measures of perceived parental affection and control during childhood were administered to 218 widowed adults 11 months after the death of the spouse. Self‐esteem, spousal dependency, depression, and suicidality were assessed 9 months later. Dependency on the deceased spouse mediated a significant association between retrospectively reported parental control during childhood and post‐loss depressive symptoms. Depressive symptoms mediated significant associations of dependency on the deceased spouse and low self‐esteem with suicidal ideation and behavior.
Psychache and Suicide: A Preliminary Investigation
Authors: Pompili Maurizio , Lester David , Leenaars Antoon A. , Tatarelli Roberto , Girardi Paolo
Published: March 2008

Shneidman's Psychological Pain Assessment Scale (PPAS; 1999) was administered to 88 psychiatric patients. Both current and worst‐ever psychache were significantly higher in those patients judged by a psychiatrist, on the basis of a structured clinical interview, to be at risk of suicide. However, current and worst‐ever psychache were not associated with having attempted suicide in the past. Thus, for the present sample of psychiatric patients, the PPAS appears to be more sensitive to current suicidality than to past suicidality. Further, there are validity issues with the PPAS, with the need for multi‐item measures and probably a multi‐factor measure.
What Prevents Adolescents from Seeking Help After a Suicide Education Program?
Authors: Cigularov Konstantin , Chen Peter Y. , Thurber Beverly W. , Stallones Lorann
Published: March 2008

Perceived barriers to help‐seeking among adolescents attending a suicide education program were examined. A total of 854 high school students in Colorado completed one of two questionnaires, measuring barriers to help‐seeking for self or friend. The most prominent barriers for self were: inability to discuss problems with adults, self‐overconfidence, fear of hospitalization, and lack of closeness to school adults. The most prominent barriers for troubled friends were: friendship concerns, unapproachability of school adults, fear of friend's hospitalization, and underestimating friend's problems. Results reveal multiple constraints limiting the program's utilization, supporting the need for comprehensive system approaches to suicide prevention.
Callosal Contributions to Simultaneous Bimanual Finger Movements
Authors: Bonzano Laura , Tacchino Andrea , Roccatagliata Luca , Abbruzzese Giovanni , Mancardi Giovanni Luigi , Bove Marco
Published: March 2008

Corpus callosum (CC) is involved in the performance of bimanual motor tasks. We asked whether its functional role could be investigated by combining a motor behavioral study on bimanual movements in multiple sclerosis (MS) patients with a quantitative magnetic resonance diffusion tensor imaging (DTI) analysis of CC, which is shown to be damaged in this disease. MS patients and normal subjects were asked to perform sequences of bimanual finger opposition movements at different metronome rates; then we explored the structural integrity of CC by means of DTI. Significant differences in motor performance, mainly referred to timing accuracy, were observed between MS patients and control subjects. Bimanual motor coordination was impaired in MS patients as shown by the larger values of the interhand interval observed at all the tested metronome rates with respect to controls. Furthermore, DTI revealed a significant reduction of fractional anisotropy (FA), indicative of microstructural tissue damage, in the CC of MS patients. By correlating the mean FA values with the different motor behavior parameters, we found that the degree of damage in the anterior callosal portions mainly influences the bimanual coordination and, in particular, the movement phase preceding the finger touch. Finally, the described approach, which correlates quantitative measures of tissue damage obtained by advanced magnetic resonance imaging tools with appropriate behavioral measurements, may help the exploration of different aspects of motor performance impairment attributable to the disease.
Deafferentation-Induced Activation of NFAT (Nuclear Factor of Activated T-Cells) in Cochlear Nucleus Neurons during a Developmental Critical Period: A Role for NFATc4-Dependent Apoptosis in the CNS
Authors: Luoma Jessie I. , Zirpel Lance
Published: March 2008

During the development and maturation of sensory neurons, afferent activity is required for normal maintenance. There exists a developmental window of time when auditory neurons, including neurons of the anteroventral cochlear nucleus (AVCN), depend on afferent input for survival. This period of time is often referred to as a critical period. The cellular and molecular mechanisms that underlie AVCN neuron susceptibility to deafferentation-induced death remain unknown. Here, we show that only during this critical period deafferentation of mouse AVCN neurons byin vivocochlea removal results in rapid nuclear translocation and activation of the transcription factor NFATc4 (nuclear factor of activated T-cells isoform 4). NFAT activation is abolished byin vivotreatment with the calcineurin inhibitor FK506 and the specific NFAT-inhibitor 11R-VIVIT. Inhibition of NFAT significantly attenuates deafferentation-induced apoptosis of AVCN neurons and abolishes NFAT-mediated expression of FasL, an initiator of apoptotic pathways, in the cochlear nucleus. These data suggest that NFAT-mediated gene expression plays a role in deafferentation-induced apoptosis of cochlear nucleus neurons during a developmental critical period.