bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exact Solutions of a Class of Two-Phase Stefan Problems in Heterogeneous Cylinders and Spheres
Authors: Layeni Olawanle P. , Ilori Olusoji , Ajayi Ebenezer O. B. 
Published: October 2014

The classical Stefan problem proffers a suitable model for determining the temperature regimes as well as conjugate interfacial positions for multiphase problems. Obtaining the solutions to these problems exactly, especially in systems with cylindrical or spherical symmetry, is often an arduous task. This is largely due to inherent nonlinearities in the mathematical statements of Stefan problems.
In this paper, a tractable and effective approach is proposed. Subsequent to a recast as a system of differential-difference equations, and a methodical reduction to constant coefficient difference equations, exact similarity solutions are derived for a class of heterogeneous two-phase Stefan problems with cylindrical or spherical symmetry in one spatial dimension, under either Gaussian or hypergeometric perturbations.
Analysis of Static Strength and Failure Mode of FSSW Joint in Aluminum Alloy
Authors: Vivio Francesco , Vullo Vincenzo , Fanelli Pierluigi 
Published: October 2014

In this paper an analysis of Friction Stir Spot Welds (FSSW), applied to lap joint aluminum alloy is presented. The analyses regards the structural behavior of FSSW joints in order to assess the failure mode and its dependence on mechanical properties distribution of the sheets material and, consequently, on process parameters.
FSSW joint is analyzed by means of a complex 3D FE model, which allows to evaluate, in a parametric manner, the multifaceted internal geometry of the joint and the actual distribution of material mechanical characteristics after welding. Experimental tests allowed to verify the results and to calibrate the material characteristics in the FE model.
Pregnant Occupant Model Including a Fetus for Vehicle Safety Investigations
Authors: Acar B. Serpil , Moustafa M. , Esat Volkan , Acar Memis 
Published: October 2014

Computational occupant modelling has an effective role to play in investigating road safety. Realistic representation of occupants is very important to make investigations in virtual environment. Pregnant occupant modelling can help investigating safety for unborn occupants (fetuses) however, existing pregnant occupant models are not very realistic. Most do not anthropometrically represent pregnant women and do not include a fetus model.
‘Expecting’, a computational pregnant occupant model, developed with a view to simulate the dynamic response to crash impacts is briefly explained in this paper. The model is validated through rigid bar impacts and belt loading tests and used to simulate a wide range of impacts. ‘Expecting’, possess the anthropometric properties of a 5th percentile female at around the 38th week of pregnancy. The model is complete with a finite element uterus and a realistic multibody fetus which is a novel feature in models of this kind.
In this paper, the effect of further developments to ‘Expecting’, by incorporating a finite element fetus head model is investigated. Further detailed anatomic geometry is used to generate deformable fetus head model. The model is used to simulate a range of frontal impacts with seatbelt and airbag, as well as no restraint cases. The strains developed in the utero-placental interface are used as the main criteria for fetus safety. The effect of incorporating a finite element fetus head in the pregnant occupant model is discussed.
Engineer Solutions Decreasing Seepage Losses From Enguri Pressure Tunnel
Authors: Kalabegishvili M. 
Published: October 2014

The majority of pressure tunnels are designed with pervious concrete lining, considering limited parameters (quantity and opening) equidistributed cracks. In general, according to the requirements of building specifications admissible seepage losses from tunnel shall not exceed 1% of HPP design discharge. As shown by the operation of HPP’s the value of seepage losses is in reality much higher than the acceptable one.
The Inguri HPP pressure tunnel (15 km in length and 9.5 m in diameter) passes in complex geological conditions. The maximum value of pressure at the beginning and end of tunnel is, correspondingly, 110–175 m, while the water level variability in the reservoir is 90 m.
The main characteristic of the structure of diversion tunnel is that in the main part of its length it is represented as a single complex: concrete lining (0.5 m thick) with strengthened grouting zone (6 m deep). Such design decision replaced more traditional structures, e.g. strengthened concrete, combined or metal linings.
The internal pressure of tunnel is borne by the monolithic mass formed by reinforcement grouting. Thereby lining operation is completely dependent on the parameters characteristic for the zone of strengthened grouting (resilient backpressure and perviousness), which must satisfy design values. Thus reinforcement grouting, along with filling grouting are integral parts of pressure tunnel, without which the operation of structure is practically impossible.
At the initial stage of operation (in 1985, at the low level in the reservoir and under the impact of the increase of pressures from massif the loss of lining stability (of the wall and inverted arch) occurred. Presently, based on general assessment the seepage losses developed from tunnel reach up to 10 m3/sec, which thrice exceed the design ones.
As a result of rehabilitation works (massif grouting and shotcrete lining) conducted in 2006 in certain sections of tunnel seepage losses were temporarily reduced. Subsequently seepage losses increased again due to the development of erosive leakage processes in massif.
In the present work calculations were conducted of the seepage parameters and stress condition of the “tunnel-massif” system during filling and discharge of reservoir using a static-seepage coupled scheme, in which a complex geological structure of massif (anisotropy, presence of cracks), the deformation of massif and seepage body force developed in it are taken into consideration. The processes developed during operational period, including depression surface enlarged and the loss of concrete lining stability, are also analyzed.
Inguri HPP is Georgia’s powerful energy object (capacity – 1300 MW, design head – 450 m). Clearly the reduction of seepage losses has a great impact on power generation. In future the rehabilitation of tunnel is envisaged, as alternative options of which shotcrete lining is viewed, the same with strengthening grouting zone and stressed lining (with expanding cement). The present work presents part of the research.
Finite-Element Simulation of Temperature Fields and Residual Stresses in Butt Welded Joints and Comparison With Experimental Measurements
Authors: Armentani Enrico , Pozzi Angela , Sepe Raffaele 
Published: October 2014

Welding is used in fabrication of structures ranging from small components to large and important structures. One of the important problems associated with welded structures is development of residual stresses and deformations due to welding temperature. In fact when structures are manufactured by welding, a non-uniform temperature distribution is produced. This distribution initially causes a rapid thermal expansion followed by a thermal contraction in the weld and surrounding areas, thus generating inhomogeneous plastic deformation and residual stresses in the weldment when it is cooled. High residual stresses in regions close to the weld may promote brittle fracture, fatigue, or stress corrosion cracking. Meanwhile, distortion in base plate may reduce the buckling strength of structural members. Therefore estimating the magnitude and distribution of welding residual stresses and distortion are necessary for achieving the safest design.
In the present work an elastic-plastic finite element model considering temperature dependent mechanical properties is used to evaluate residual stresses. In this study a parametric model is adopted and the elements birth and death are used in single-pass butt welded joint to simulate the weld filler variation with time. Then numerical results are compared with experimental data.
Numerical Simulation of Tooth Surface Finish Effects on Gear Noise
Authors: Jolivet S. , Mezghani S. , El Mansori M. , Zahouani H. 
Published: October 2014

Due to the rapid development of electric and hybrid motorisations, gear manufacturers have encountered an increasing need to create high level quality gear flanks. While the main goals are to increase the load-carrying capacity and the wear resistance, reducing gear noise has become more and more important. To answer this, macro- and micro-geometry defects have long been studied as well as their effect in amplifying the vibrations of gears. However, the impact of tooth flanks micro-scale roughness on gear noise has not well been studied and understood, even though the teeth surface contacts are essential in the gear mechanics.
This paper aimed to discriminate the influence of the tooth finishing process (grinding, powerhoning) on single stage spur gear noise. A two-dimensional finite-element simulation model of a one-stage gear system was hence developed. The transmission system was composed of two identical loaded gears with one degree of freedom. Topological features of teeth surfaces finished by grinding and powerhoning were measured with a three-dimensional white light interferometer. These real topographic profiles of the tooth surfaces were integrated in the model. The meshing stiffness was determined as an output of this dynamic model. It is a parameter directly linked to the acoustic behaviour of the gear. Results show that gear noise could be reduced by the right choice of the finishing process kinematic.
Numerical Simulation and Control of Rotating Stall in a Transonic Centrifugal Compressor
Authors: Halawa Taher , Alqaradawi Mohamed , Badr Osama , Gadala Mohamed S. 
Published: October 2014

This study presents a numerical simulation of precursors and characteristics of rotating stall in a centrifugal compressor with vaned diffuser. The aim is to further understand the causes of stall inception, characteristics of stall process and to investigate reliable simulation of stall control methods and aid in their optimization. Initial numerical results show that the tip leakage flow and early separation in the impeller blades are causing weakness of radial velocity and deviation of fluid angle at impeller exit.
Also, results show that the vaneless region between impeller and diffuser near shroud surface is the key factor of developing radial velocity deficiency into stall cells leading to pressure fluctuations on impeller blades. The present study confirms that injection of air at the shroud surface of the vaneless region has an effect on modifying fluid angle entering diffuser and on delaying of stall inception to occur at lower mass flow rates.
Metagenomic Analysis of Viruses in Feces from Unsolved Outbreaks of Gastroenteritis in Humans
Authors: Moore Nicole E. , Wang Jing , Hewitt Joanne , Croucher Dawn , Williamson Deborah A. , Paine Shevaun , Yen Seiha , Greening Gail E. , Hall Richard J. 
Published: October 2014

ABSTRACT

The etiology of an outbreak of gastroenteritis in humans cannot always be determined, and ∼25% of outbreaks remain unsolved in New Zealand. It is hypothesized that novel viruses may account for a proportion of unsolved cases, and new unbiased high-throughput sequencing methods hold promise for their detection. Analysis of the fecal metagenome can reveal the presence of viruses, bacteria, and parasites which may have evaded routine diagnostic testing. Thirty-one fecal samples from 26 gastroenteritis outbreaks of unknown etiology occurring in New Zealand between 2011 and 2012 were selected for
de novo
metagenomic analysis. A total data set of 193 million sequence reads of 150 bp in length was produced on an Illumina MiSeq. The metagenomic data set was searched for virus and parasite sequences, with no evidence of novel pathogens found. Eight viruses and one parasite were detected, each already known to be associated with gastroenteritis, including adenovirus, rotavirus, sapovirus, and
Dientamoeba fragilis
. In addition, we also describe the first detection of human parechovirus 3 (HPeV3) in Australasia. Metagenomics may thus provide a useful audit tool when applied retrospectively to determine where routine diagnostic processes may have failed to detect a pathogen.
A Study of Genotyping for Management of Human Papillomavirus-Positive, Cytology-Negative Cervical Screening Results
Authors: Schiffman M. , Burk R. D. , Boyle S. , Raine-Bennett T. , Katki H. A. , Gage J. C. , Wentzensen N. , Kornegay J. R. , Aldrich C. , Tam T. , Erlich H. , Apple R. , Befano B. , Castle P. E. 
Published: October 2014

ABSTRACT

The effective management of women with human papillomavirus (HPV)-positive, cytology-negative results is critical to the introduction of HPV testing into cervical screening. HPV typing has been recommended for colposcopy triage, but it is not clear which combinations of high-risk HPV types provide clinically useful information. This study included 18,810 women with Hybrid Capture 2 (HC2)-positive, cytology-negative results and who were age ≥30 years from Kaiser Permanente Northern California. The median follow-up was 475 days (interquartile range [IQR], 0 to 1,077 days; maximum, 2,217 days). The baseline specimens from 482 cases of cervical intraepithelial neoplasia grade 3 or cancer (CIN3+) and 3,517 random HC2-positive noncases were genotyped using 2 PCR-based methods. Using the case-control sampling fractions, the 3-year cumulative risks of CIN3+ were calculated for each individual high-risk HPV type. The 3-year cumulative risk of CIN3+ among all women with HC2-positive, cytology-negative results was 4.6%. HPV16 status conferred the greatest type-specific risk stratification; women with HC2-positive/HPV16-positive results had a 10.6% risk of CIN3+, while women with HC-2 positive/HPV16-negative results had a much lower risk of 2.4%. The next most informative HPV types and their risks in HPV-positive women were HPV33 (5.9%) and HPV18 (5.9%). With regard to the etiologic fraction, 20 of 71 cases of cervical adenocarcinoma
in situ
(AIS) and adenocarcinoma in the cohort were positive for HPV18. HPV16 genotyping provides risk stratification useful for guiding clinical management; the risk among HPV16-positive women clearly exceeds the U.S. consensus risk threshold for immediate colposcopy referral. HPV18 is of particular interest because of its association with difficult-to-detect glandular lesions. There is a less clear clinical value of distinguishing the other high-risk HPV types.
Development of an Efficient Entire-Capsid-Coding-Region Amplification Method for Direct Detection of Poliovirus from Stool Extracts
Authors: Arita Minetaro , Kilpatrick David R. , Nakamura Tomofumi , Burns Cara C. , Bukbuk David , Oderinde Soji B. , Oberste M. Steven , Kew Olen M. , Pallansch Mark A. , Shimizu Hiroyuki 
Published: October 2014

ABSTRACT
Laboratory diagnosis has played a critical role in the Global Polio Eradication Initiative since 1988, by isolating and identifying poliovirus (PV) from stool specimens by using cell culture as a highly sensitive system to detect PV. In the present study, we aimed to develop a molecular method to detect PV directly from stool extracts, with a high efficiency comparable to that of cell culture. We developed a method to efficiently amplify the entire capsid coding region of human enteroviruses (EVs) including PV. cDNAs of the entire capsid coding region (3.9 kb) were obtained from as few as 50 copies of PV genomes. PV was detected from the cDNAs with an improved PV-specific real-time reverse transcription-PCR system and nucleotide sequence analysis of the VP1 coding region. For assay validation, we analyzed 84 stool extracts that were positive for PV in cell culture and detected PV genomes from 100% of the extracts (84/84 samples) with this method in combination with a PV-specific extraction method. PV could be detected in 2/4 stool extract samples that were negative for PV in cell culture. In PV-positive samples, EV species C viruses were also detected with high frequency (27% [23/86 samples]). This method would be useful for direct detection of PV from stool extracts without using cell culture.
Use of Whole-Genus Genome Sequence Data To Develop a Multilocus Sequence Typing Tool That Accurately Identifies Yersinia Isolates to the Species and Subspecies Levels
Authors: Hall Miquette , Chattaway Marie A. , Reuter Sandra , Savin Cyril , Strauch Eckhard , Carniel Elisabeth , Connor Thomas , Van Damme Inge , Rajakaruna Lakshani , Rajendram Dunstan , Jenkins Claire , Thomson Nicholas R. , McNally Alan 
Published: October 2014

ABSTRACT

The genus
Yersinia
is a large and diverse bacterial genus consisting of human-pathogenic species, a fish-pathogenic species, and a large number of environmental species. Recently, the phylogenetic and population structure of the entire genus was elucidated through the genome sequence data of 241 strains encompassing every known species in the genus. Here we report the mining of this enormous data set to create a multilocus sequence typing-based scheme that can identify
Yersinia
strains to the species level to a level of resolution equal to that for whole-genome sequencing. Our assay is designed to be able to accurately subtype the important human-pathogenic species
Yersinia enterocolitica
to whole-genome resolution levels. We also report the validation of the scheme on 386 strains from reference laboratory collections across Europe. We propose that the scheme is an important molecular typing system to allow accurate and reproducible identification of
Yersinia
isolates to the species level, a process often inconsistent in nonspecialist laboratories. Additionally, our assay is the most phylogenetically informative typing scheme available for
Y. enterocolitica
.
Use of Transrenal DNA for the Diagnosis of Extrapulmonary Tuberculosis in Children: a Case of Tubercular Otitis Media
Authors: Petrucci Roberta , Lombardi Giulia , Corsini Ilaria , Visciotti Francesca , Pirodda Antonio , Cazzato Salvatore , Landini Maria Paola , Dal Monte Paola 
Published: October 2014

ABSTRACT

The diagnosis of tuberculosis (TB) is difficult in children, especially for smear-negative pulmonary and extrapulmonary TB, which are common at this age. We report an 11-year-old girl with TB otitis media with negative smear microscopy and Xpert MTB/RIF but positive
Mycobacterium tuberculosis
-specific transrenal DNA (Tr-MTB-DNA) test results and culture for
M. tuberculosis
.
Unbiased Species-Level Identification of Clinical Isolates of Coagulase-Negative Staphylococci: Does It Change the Perspective on Staphylococcus lugdunensis?
Authors: Elamin Wael F. , Ball David , Millar Michael 
Published: October 2014

ABSTRACT

Unbiased species-level identification of coagulase-negative staphylococci (CoNS) using matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) identified
Staphylococcus lugdunensis
to be a more commonly isolated CoNS in our laboratory than previously observed. It has also highlighted the possibility of vertical transmission.
Clonal Evolution of CD8+T Cell Responses against Latent Viruses: Relationship among Phenotype, Localization, and Function
Authors: Remmerswaal Ester B. M. , Klarenbeek Paul L. , Alves Nuno L. , Doorenspleet Marieke E. , van Schaik Barbera D. C. , Esveldt Rebecca E. E. , Idu Mirza M. , van Leeuwen Ester M. M. , van der Bom-Baylon Nelly , van Kampen Antoine H. C. , Koch Sven D. , Pircher Hanspeter , Bemelman Frederike J. , ten Brinke Anja , Baas Frank , ten Berge Ineke J. M. , van Lier Rene A.W. , de Vries Niek 
Published: October 2014

ABSTRACTHuman cytomegalovirus (hCMV) infection is characterized by a vast expansion of resting effector-type virus-specific T cells in the circulation. In mice, interleukin-7 receptor α (IL-7Rα)-expressing cells contain the precursors for long-lived antigen-experienced CD8+T cells, but it is unclear if similar mechanisms operate to maintain these pools in humans. Here, we studied whether IL-7Rα-expressing cells obtained from peripheral blood (PB) or lymph nodes (LNs) sustain the circulating effector-type hCMV-specific pool. Using flow cytometry and functional assays, we found that the IL-7Rα+hCMV-specific T cell population comprises cells that have a memory phenotype and lack effector features. We used next-generation sequencing of the T cell receptor to compare the clonal repertoires of IL-7Rα+and IL-7Rα−subsets. We observed limited overlap of clones between these subsets during acute infection and after 1 year. When we compared the hCMV-specific repertoire between PB and paired LNs, we found many identical clones but also clones that were exclusively found in either compartment. New clones that were found in PB during antigenic recall were only rarely identical to the unique LN clones. Thus, although PB IL-7Rα-expressing and LN hCMV-specific CD8+T cells show typical traits of memory-type cells, these populations do not seem to contain the precursors for the novel hCMV-specific CD8+T cell pool during latency or upon antigen recall. IL-7Rα+PB and LN hCMV-specific memory cells form separate virus-specific compartments, and precursors for these novel PB hCMV-specific CD8+effector-type T cells are possibly located in other secondary lymphoid tissues or are being recruited from the naive CD8+T cell pool.IMPORTANCEInsight into the self-renewal properties of long-lived memory CD8+T cells and their location is crucial for the development of both passive and active vaccination strategies. Human CMV infection is characterized by a vast expansion of resting effector-type cells. It is, however, not known how this population is maintained. We here investigated two possible compartments for effector-type cell precursors: circulating acute-phase IL-7Rα-expressing hCMV-specific CD8+T cells and lymph node (LN)-residing hCMV-specific (central) memory cells. We show that new clones that appear after primary hCMV infection or during hCMV reactivation seldom originate from either compartment. Thus, although identical clones may be maintained by either memory population, the precursors of the novel clones are probably located in other (secondary) lymphoid tissues or are recruited from the naive CD8+T cell pool.