bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Labyrinth Seal Leakage on the Turbine Support Cooling
Authors: Vinogradov Alexandr S. , Badykov Renat R.
Published: February 2015

This paper presents a study of the seal of supporting element in aviation engines with consideration of the mutual influence of its leakage on parameters of internal air system and engine oil system. A method of seal leakage calculation was developed. It connects engine thermogasdynamics calculation, airflow hydraulics calculation and structural analysis of deformed parts. The main sources of heat transferred to the supporting element were determined; their numerical values and percentages for the compressor and turbine were also determined.

This paper provides options of cooling the turbine support for realization of this method. A way of cooling the support determines the quantity of heat supplied to the support. Thus, this article analyzes the sources of heat. Comparison the amount of heat from different sources also is carried out. The amount of heat is defined the temperature of the cooling air. The article provides a comparison of calculation results for different temperatures of the cooling air. After selecting the geometry of the seal system, and determining of the total amount of heat, single seal from the system was researched.

The main purpose of the paper is to explain the design of a single seal as part of whole seal system, which is used to cool the support of the aircraft engine.
Performance Enhancement of the Centrifugal Compressor Stage With a Rotating Vaneless Diffuser: A Numerical Study
Authors: Sivamani Seralathan , Ghosh Roy Chowdhury Dibyakanti
Published: February 2015

In order to reduce the energy losses associated due to diffusion in the centrifugal compressor stage, several radial diffuser designs have been tried and rotating vaneless diffuser is one among them. Forced rotating vaneless diffuser is formed by extending the impeller disks alone beyond the blade tip without affecting the blade tip geometry. Studies on completely replacing a stationary vaneless diffuser with rotating vaneless diffuser are not available in open domain yet. This paper reports the effect of rotating vaneless diffuser based on shroud extension concept on flow diffusion, performance and flow parameters in a centrifugal compressor stage at design and off-design flow conditions. A backward curved impeller with diffuser diameter ratio 1.40 is chosen for the present study. Rotating vaneless diffuser is formed by extending the impeller disks by 40% above the impeller exit diameter. The comparative studies are done with the same impeller having a stationary vaneless diffuser of equivalent diffuser diameter ratio in the downstream. Static pressure rise in RVD-ES configuration is higher compared to SVD and the energy coefficient improved by around 57.14% for RVD-ES over the entire flow range. The efficiency of RVD-ES and SVD are almost identical at Φ = 0.156. At design and other off-design flow coefficients, the efficiencies of RVD-ES are slightly lesser compared to SVD by 1.0 to 1.52%. The static pressure recovery coefficient of RVD-ES is higher than SVD. The stagnation pressure losses reduced drastically for RVD-ES. From the velocity vectors and contours of stagnation pressure distribution, it seen that additional energy is added to the fluid by the rotating walls of the vaneless diffuser. This results in increased kinetic energy of the fluid. Due to better diffusion process in RVD-ES, this results with a gain in increased static pressure rise with acceptable efficiency.
Nacelle: Air Intake Aerodynamic Design and Inlet Compatibility
Authors: Chen Jingjing , Wu Yadong , Wang Zhonglin , Wang Anjenq
Published: February 2015

One of the most challenging operating conditions to be certified for FAR33 & FAR25 requirements is ground crosswind condition. When “Engine” is operated using the designed inlet and nacelle, within the flight envelope, could accommodate inlet separation/distortion resulted from crosswind and high angle-of-attack operating conditions. Inlet flow separation and distortion could trigger fan or core stall, as well as induce high fan and/or engine vibrations. The air induction system or inlet of the engine is designed to provide velocity and pressure distributions with minimum distortion and maximum pressure recovery to the propulsion system. Engine-inlet-airframe compatibility is one of the major tasks required to be evaluated in detail during the engine developing phase.

This research is a parametric study of using CFD to evaluate operational characteristics of the air induction system. Comparisons of various inlet designs are made and characterized into three categories, i.e., i) Inlet flow recovery, ii) Inlet flow distortion, iii) Inlet Mach distribution. The objective is to assess the impact of air induction design of turbofan upon inlet compatibility. The current research work includes four parts, i.e., i) A geometry modeling process of nacelle, inlet, wing and fuselage, ii) A meshes generator ICEM, iii) The ANSYS CFX CFD software which could achieves numerical simulation and post-processing, iv) The Matlab platform with the function of coupling all considerations listed above for inlet compatibility optimization, based on genetic algorithm and Kriging agent model.

The research introduces the Kriging model and weighting coefficient to optimize total pressure loss coefficient and static pressure recovery coefficient, with the external nacelle flow ignored. Bezier equation was used to fit the optimized curves obtained by changing two control points at the inter surface of nacelle. The wing-mounted model coupled with the nacelles, fuselage and wings was then built to make the assessment of inlet compatibility of air intake system relative to the isolate model. Comparison of aerodynamic performance was then made between the original and optimal nacelle, to show correlation between inlet compatibility and air intake profile.
High Cycle Fatigue Life Assessment of Compressor Blades Under Multi-Axial Fatigue Mode
Authors: Potluri Sri Shanti , Bommakanti Srinivasa Ananda Mohan , Ramasamy Isai Thamizh , Potu Srinivasa Rao , Balivada Venkata Ananda Rao Patnaik
Published: February 2015

Stringent mission requirements of Aero Gas Turbine engines result in severe aerodynamic loads on engine components. Structural integrity and durability of blades is an important aspect with fatigue being a major failure mode and especially High Cycle Fatigue being a critical design concern. HCF failures in blades are mainly attributed to resonant excitations where the dynamic stress amplitude in the blade increases as the exciting frequency approaches the resonant speed. These excitations could be due to integral orders, i.e. as multiples of rotational speeds and also due to nozzle or blade pass frequencies. The frequency of these excitations is very high and under these excitations, the blades are subjected to highly complex modes or deformation patterns resulting in a multi-axial state of stress. Other causes for multi-axial state of stress may be attributed to anisotropy in material, presence of stress raisers and end fixity/ support mechanism of the blade in context. Assessing the severity of this multi-axial stress state in the blade from HCF is very important from the designer’s perspective.

This paper describes the methodology employed in a compressor stator blade to assess the HCF damage by distortion energy based multi-axial fatigue failure criteria with a modification to include the mean static stresses. Based on this method, safe operating strain limits are established and are used as guide lines to monitor the stator blades during engine testing. When this methodology is checked for a pure bending mode of a compressor stator blade, i.e. for a state of stress which is predominantly unidirectional, both the Goodman approach and the distortion energy based multi-axial method yield the same assessment under HCF, whereas for a complex mode with a multi-axial state of stress, considerable difference in results is observed.
Designing Supercritical CO2 Power Plants Using an Integrated Design System
Authors: Nassar Abdul , Moroz Leonid , Burlaka Maksym , Pagur Petr , Govoruschenko Yuri
Published: February 2015

The use of S-CO2 as working fluid in a power cycle has been growing in recent years due to associated benefits such as highly compact power plant and high cycle thermal efficiencies for application including waste heat, solar thermal and nuclear power plants. Many authors have presented studies on S-CO2 cycle and its modifications and there also exists many patents which claim different embodiments of the S-CO2 cycle for different heat sources. Each author of the S-CO2 cycle embodiment uses some specific tool to analyze the cycle performance with assumed values of component efficiencies. In the S-CO2 cycle the ratio of turbine work to compressor work is relatively small and its variation may cause a significant influence on cycle performance estimation accuracy. Exact prediction of the S-CO2 cycle performance requires defining exact turbomachinery efficiency magnitudes. However, S-CO2 turbines and compressors are in development stage except for several low power scale prototypes and hence it is very difficult to make assumptions on efficiency and they need to be designed.

To enable design of cycle from concept to detailed design of the turbomachinery, the authors in this work have developed a flexible design system which is starting from heat balance calculation, continues with sizing of turbomachinery flow path, through 1D/2D/3D aero and structural multidisciplinary optimization. Such a design process is iterative because a refinement of the turbomachinery efficiencies lead to change in cycle boundary conditions for turbomachinery design and the design needs to be refined by recalculation of the cycle. In the present work, four different embodiments of S-CO2 thermodynamic cycles were analyzed using assumed component efficiencies and based on the actual design of the turbomachinery components the cycle was recalculated and accurate performance of the cycle was predicted. It is observed that the turbine efficiency has significant influence on the overall cycle performance compared to the compressor efficiency.
Modeling of Particle Wall Interaction and Film Transport Using Eulerian Wall Film Model
Authors: Ingle Rahul , Yadav Ravi , Punekar Hemant , Cao Jing
Published: February 2015

The growing awareness of pollutant emissions from gas turbines has made it very important to study fuel atomization system, the spray wall interaction and hydrodynamic of film formed on engine walls. A precise fuel spray spatial distribution and efficient fuel air mixing plays important role in improving combustion performance. Cross-flow injection and film atomization technique has been studied extensively for gas turbine engines to achieve efficient combustion. Air blast atomizer is one of these kind of systems used in gas turbine engines which involves shear driven prefilmer secondary atomization. In addition to gas turbine combustor shear driven liquid wall film can be seen in IC engines, rocket nozzles, heat exchangers and also on steam turbine blades.

In our work we have used Eulerian Wall Film (EWF) [1] model to simulate the experiment performed by Arienti et al. [2]. In the Arienti’s experiment liquid jet is injected from a nozzle from the top of the chamber. Droplets shed from the jet surface due to primary and later secondary atomization in the presence of high shearing cross flowing air. Further liquid fuel particles hit the wall to form film, film moves subjected to shear from the gas phase. Liquid film can reatomizes due to subgrid processes like stripping, splashing and film breakup. In current study we have validated Arienti et al. [2] experimental data by modeling complex & coupled physics of spray, film and continuous phase and by accounting complex subgrid processes.
Residual Life Estimation of Axial Compressor Blade of a Turbo-Shaft Engine
Authors: Anbarasan Selwyn , Muthu S. Esakki , Roy Hardik , Udayanan P. , Degaonkar Girish K.
Published: February 2015

In aeronautical industry, flight safety is the first and foremost concern. Structural failure in aero engine aids to high risk in flight safety and human lives. High Cycle Fatigue (HCF) failure accounts for forty percent of blade structural failure. All critical components in the aero engine are life limited components and are replaced when its prescribed life is reached. Earlier components are designed as per safe-life design philosophy. Ninety percent of the critical components are retired utilizing less than fifty percent of its safe-life capability. Extending the life of component reduces the operating cost and lowers downtime for the fleet operator.

This paper describes the life extension methodology used for a first stage axial compressor blade of turbo-shaft engine. The blade which has completed its safe life in the aircraft in service is identified. The studies are carried out to determine the residual life of the blade to extend the life. First stage axial compressor blade is made from titanium alloy and is fixed with the disc by pins. The force on the blade due to aerodynamic excitation which is required for life estimation is predicted using CFD tools followed by the estimation of alternate stress on the blade using FEM tools. Stress based life estimation methodology is used to estimate HCF life of the blade under engine operating condition. The estimated life of the blade is to be confirmed in rig testing. Life completed blades are identified from different engines for testing of the residual life. Metallurgical studies are carried out on the specimens from the blade to check the residual properties. The blades which qualify after the dimension inspection and crack detection are used for testing residual life. The blades are tested in vibration test rig facility in which incremental fatigue testing method is employed. The blades are excited by the electro-dynamic shaker at its first natural frequency (1F mode) and the amplitude is increased in steps in a steady interval of time. The HCF life of the blade is calculated by Miner’s hypothesis. The residual life of the blade is estimated by vibration rig testing and is compared with the numerical estimation. It is found that the residual life of the life completed component has got potential life of one more overhaul.
Prediction of Fatigue and Fracture Life of an Autofrettaged Turbine Compressor Disc Using Finite Element Analysis
Authors: Jagannath Suman Mittemari Lakshminarayan , Srinivasan Srikari , Gopalakrishnan Mahesh , Banthia Vinod Kumar
Published: February 2015

Gas turbine compressor discs are highly stressed components as they rotate at high speed. Bore region of the disc is the most critical region because any failure at the bore would lead to catastrophic failure of entire gas turbine. Engine start-up and shutdown, as well as major throttle excursions during operation, induce cyclic tensile stresses in this region. These cyclic tensile stresses can exceed yield strength of the material and can thus lead to low cycle fatigue failure. Hence, there is a strong need to enhance fatigue and fracture life of the bore region in order to meet the growing design life requirements.

In the present work, method of autofrettage to reduce tensile stresses at bore region has been evaluated. In this case, pre-spin has been used to induce compressive pre-stresses in the bore region. A typical gas turbine compressor rotor forward stage disc was modeled based on design parameters available in literature. Analysis was carried out in 2 stages — non-linear structural analysis of pre-spin to induce compressive stresses and then with operation load to evaluate the effect of pre-stress on stresses and fatigue life in operational conditions in the bore region. Stress intensity factor, KI at the bore region was used to calculate fracture life using LEFM methodology.

Comparison of the results for post-spin life with that of the baseline showed 3 times increases in fatigue and 75% increase in fracture life.
Computational Study of Flow and Heat Transfer in Matrix Cooling Channels
Authors: Ramireddy Sivasankara Reddy , Gurusiddappa Siddappa Pallavagere , Kesavan V. , Kumar S. Kishore
Published: February 2015

A Numerical study of fluid flow, heat transfer and pressure drop in a stationary matrix cooling channel having an angle of 45 degrees for the three Reynolds numbers (24000<Re<60000) and four sub-channel aspect ratios (0.5<W/H<1.2) have been performed. This includes different shaped sub-channels such as Rectangular, U, and then two, three layered matrix combined with open and closed matrix channels. The simulation shows the development of vortices along the channel. The flow turning and impingement after hitting the side wall have significant contribution to the heat transfer enhancement. The Nusselt number and friction factor have been evaluated and compared with limited experimental results. The highest heat transfer enhancement is found at impingement region as the flow takes turn and impinges on to the wall. But slight enhancement in heat transfer is observed at turning region. The sub-channel aspect ratio has less impact on heat transfer enhancement, but more effect on pressure drop. The performance of closed matrix is relatively better than the open matrix one. The overall thermal performance (η) of the matrix having U sub-channel is nearly 10% higher than the rectangular sub-channel.
Investigation of Combustion Oscillations of Premixed Dump Combustor Using Time-Resolved Particle Image Velocimetry
Authors: Sampath Ramgopal , Ramanan Vikram , Chakravarthy S. R.
Published: February 2015

The present work deals with time-resolved investigation of the flow field during acoustic self-excitation by a lean premixed flame in a dump combustor with varying equivalence ratio at a constant air flow rate. Simultaneous measurements of pressure fluctuations, velocity fields using Time resolved Particle imaging velocimetry (TR-PIV) and CH* chemiluminescence were performed. The pressure, velocity and chemiluminescent intensity time traces were Fourier transformed to estimate the frequency and amplitudes. Conditions of maximum pressure amplitude correspond to the prevalence of intermittent bursts in pressure, velocity, and chemiluminescent intensity. Further, Proper orthogonal decomposition (POD) is applied to the chemiluminescent intensity and velocity fields. The POD mode shapes are able to capture the modes pertaining to both the acoustic and vortex mode of flame/flow oscillations. The burst oscillations are understood by examining the sequence of time-resolved velocity and chemiluminescent intensity during their growth and decay regimes. The growth of oscillations is promoted by the flame heat release fluctuations following the pattern of the large-scale vortex roll-up in the recirculation zone downstream of the dump plane, causing a tendency of acoustic excitation at the vortex mode. As the amplitude rises, the natural acoustic mode of the duct is simultaneously amplified, leading to small-scale vortices shed from the step corner at the acoustic time scale. These small-scale vortices adversely interact with the large-scale vortex controlling the heat release, resulting in its weakening and hence the decay of oscillations. This behavior was further observed in the spatially averaged vorticity along the shear layer. In addition to this, the time traces of the pressure and the velocity fluctuations at the shear layer and located half step height from the separation point were overlapped. The overlapped time traces showed a drift in the instantaneous phase during which the growth and decay of the oscillations were observed.
Analysis of Different Radiation Models in a Swirl Stabilized Combustor
Authors: Sharma Aayush K. , Bhattacharya Chandrachur , Sen Swarnendu , Mukhopadhyay Achintya , Datta Amitava
Published: February 2015

A computational study on spray combustion, using kerosene (C12H23) as fuel, in a model gas turbine combustor has been carried out. The numerical modelling of radiation heat transfer is carried out in a three-dimensional swirl stabilized, liquid-fuelled combustor. The Favre-averaged governing equations are solved using Ansys Fluent 14.5 as the CFD package. The turbulence parameters are computed using realizable k-ε with standard wall functions model. Eulerian-Lagrangian approach is used to track stochastically the motion of the evaporation species in the continuous gas phase. The effect of different radiation models — Discrete Ordinate (DO), P1 and Discrete Transfer Radiation Model (DTRM) along with Soot are analysed in the present study. To validate the results of radiation modelling carried out in the present work, the computational results have been compared with previous experimental data for the same combustor geometry. The numerical data considering effect of soot along with radiation is shown to closely approximate the experimental data. An attempt has also been made to introduce a liner in the combustor and evaluate its effect and the heat transfer across the liner for the present numerical model.
Pulmonary nodule detection in CT images based on shape constraint CV model
Authors: Wang Bing , Tian Xuedong , Wang Qian , Yang Ying , Xie Hongzhi , Zhang Shuyang , Gu Lixu
Published: February 2015

Purpose:

Accurate detection of pulmonary nodules remains a technical challenge in computer‐aided diagnosis systems because some nodules may adhere to the blood vessels or the lung wall, which have low contrast compared to the surrounding tissues. In this paper, the analysis of typical shape features of candidate nodules based on a shape constraint Chan–Vese (CV) model combined with calculation of the number of blood branches adhered to nodule candidates is proposed to reduce false positive (FP) nodules from candidate nodules.

Methods:

The proposed scheme consists of three major stages: (1) Segmentation of lung parenchyma from computed tomography images. (2) Extraction of candidate nodules. (3) Reduction of FP nodules. A gray level enhancement combined with a spherical shape enhancement filter is introduced to extract the candidate nodules and their sphere‐like contour regions. FPs are removed by analysis of the typical shape features of nodule candidates based on the CV model using spherical constraint and by investigating the number of blood branches adhered to the candidate nodules. The constrained shapes of CV model are automatically achieved from the extracted candidate nodules.

Results:

The detection performance was evaluated on 127 nodules of 103 cases including three types of challenging nodules, which are juxta‐pleural nodules, juxta‐vascular nodules, and ground glass opacity nodules. The free‐receiver operating characteristic (FROC) curve shows that the proposed method is able to detect 88% of all the nodules in the data set with 4 FPs per case.

Conclusions:

Evaluation shows that the authors’ method is feasible and effective for detection of three types of nodules in this study.
‘Let Them Get on With It’: Coaches’ Perceptions of Their Roles and Coaching Practices During Olympic and Paralympic Games
Authors: Ritchie Darren , Allen Justine
Published: February 2015

How coaches prepare and perform is critical for athletes’ performances (Gould, Guinan, Greenleaf & Chung, 2002), however, little is known about coaches’ roles and coaching practices during major competitions such as the Olympic or Paralympic Games. To assist coaches in their efforts to improve athletes’ performances in competition environments, greater understanding is needed about the coaching process during major competitions and how coaches prepare and perform. Therefore, the purpose of the current study was to examine track and field coaches’ perceptions of their roles and coaching practices during competition at major events. Eight coaches, seven male and one female, who had coached one or more athletes to an Olympic or Paralympic medal were interviewed. Inductive content analysis indicated that creating an athlete focused supportive environment, detailed preparation and planning, use of effective observation and limited intervention, coach and athlete psychological preparation and managing the process were salient during competition at major events. These findings suggest that during major competition the coach’s role is supportive and facilitative. Actions are largely unobtrusive and in response to athletes’ needs, but remain as detailed as other phases of the coaching process. The findings are discussed in relation to the coach as orchestrator.
Coach Evaluation From Three Perspectives: An Athletic Director, a Coach and a Consultant
Authors: Gillham Andy , Hansen Keith , Brady Connor
Published: February 2015

Coaches are evaluated and judged on a large number of factors (Gillham, Burton, & Gillham, 2013). The purpose of this paper is to describe the views of three different professionals on coach evaluation. An athletic director and a coach from different Canadian colleges and a coaching consultant responded to the same series of questions regarding coach evaluation at the college level. Across the three professionals, the views expressed are more similar than dissimilar, with each professional emphasizing a different piece of the coach evaluation process. The information presented aligns both with coaching standards in the United States and at the International level. Stakeholder views are compared with the coaching science literature and recommendations for athletic directors and coaching scientists are provided.
Immunoproteomic Identification ofIn Vivo-Produced Propionibacterium acnes Proteins in a Rabbit Biofilm Infection Model
Authors: Achermann Yvonne , Tran Bao , Kang Misun , Harro Janette M. , Shirtliff Mark E.
Published: February 2015

Propionibacterium acnesis well-known as a human skin commensal but can also act as an invasive pathogen causing implant-associated infections. In order to resolve these types ofP. acnesinfections, the implants must be removed, due to the presence of an established biofilm that is recalcitrant to antibiotic therapy. In order to identify thoseP. acnesproteins producedin vivoduring a biofilm infection, we established a rabbit model of implant-associated infection with this pathogen.P. acnesbiofilms were anaerobically grown on dextran beads that were then inoculated into the left tibias of rabbits. At 4 weeks postinoculation,P. acnesinfection was confirmed by radiograph, histology, culture, and PCR.In vivo-produced and immunogenicP. acnesproteins were detected on Western blot using serum samples from rabbits infected withP. acnesafter these bacterial proteins were separated by two-dimensional gel electrophoresis. Those proteins that bound host antibodies were then isolated and identified by tandem mass spectrometry. Radiographs and histology demonstrated a disruption in the normal bone architecture and adherent biofilm communities in those animals with confirmed infections. A total of 24 immunogenic proteins were identified; 13 of these proteins were upregulated in both planktonic and biofilm modes, including an ABC transporter protein. We successfully adapted a rabbit model of implant-associated infection forP. acnesto identifyP. acnesproteins produced during a chronic biofilm-mediated infection. Further studies are needed to evaluate the potential of these proteins for either a diagnostic test or a vaccine to prevent biofilm infections caused byP. acnes.
Genomic and Epidemiological Characteristics Provide New Insights into the Phylogeographical and Spatiotemporal Spread of Porcine Epidemic Diarrhea Virus in Asia
Authors: Sun Min , Ma Jiale , Wang Yanan , Wang Ming , Song Wenchao , Zhang Wei , Lu Chengping , Yao Huochun
Published: February 2015

Porcine epidemic diarrhea has become pandemic in the Asian pig-breeding industry, causing significant economic loss. In the present study, 11 complete genomes of porcine epidemic diarrhea virus (PEDV) field isolates from China were determined and analyzed. Frequently occurring mutations were observed, which suggested that full understanding of the genomic and epidemiological characteristics is critical in the fight against PEDV epidemics. Comparative analysis of 49 available genomes clustered the PEDV strains into pandemic (PX) and classical (CX) groups and identified four hypervariable regions (V1 to V4). Further study indicated key roles for the spike (S) gene and the V2 region in distinguishing between the PX and CX groups and for studying genetic evolution. Genotyping and phylogeny-based geographical dissection based on 219 S genes revealed the complexity and severity of PEDV epidemics in Asia. Many subgroups have formed, with a wide array of mutations in different countries, leading to the outbreak of PEDV in Asia. Spatiotemporal reconstruction based on the analysis suggested that the pandemic group strains originated from South Korea and then extended into Japan, Thailand, and China. However, the novel pandemic strains in South Korea that appeared after 2013 may have originated from a Chinese variant. Thus, the serious PED epidemics in China and South Korea in recent years were caused by the complex subgroups of PEDV. The data in this study have important implications for understanding the ongoing PEDV outbreaks in Asia and will guide future efforts to effectively prevent and control PEDV.
Disseminated Rhinovirus C8 Infection with Infectious Virus in Blood and Fatal Outcome in a Child with Repeated Episodes of Bronchiolitis
Authors: Lupo Julien , Schuffenecker Isabelle , Morel-Baccard Christine , Bardet Julie , Payen Valérie , Kaiser Laurent , Constant Samuel , Lobrinus Johannes Alexander , Lin-Marq Nathalie , Lina Bruno , Morand Patrice , Tapparel Caroline
Published: February 2015

We report a fatal case of acute lower respiratory tract disease with human rhinovirus C (HRV-C) as the unique cause in a 19-month-old girl with a history of repeated episodes of bronchiolitis. HRV-C type 8 nucleic acids were observed in respiratory, stool, and cerebrospinal fluid samples, and infectious virions were isolated from patient serum after inoculation onto reconstituted airway epithelia.
Analysis of a Local HIV-1 Epidemic in Portugal Highlights Established Transmission of Non-B and Non-G Subtypes
Authors: Carvalho Alexandre , Costa Patrício , Triunfante Vera , Branca Fernando , Rodrigues Fernando , Santos Catarina L. , Correia-Neves Margarida , Saraiva Margarida , Lecour Henrique , Castro António G. , Pedrosa Jorge , Osório Nuno S.
Published: February 2015

The existing data support Portugal as the western European country with the highest HIV-1 subtype diversity. However, detailed phylogenetic studies of Portuguese HIV-1 epidemics are still scarce. Thus, our main goal was to analyze the phylodynamics of a local HIV-1 infection in the Portuguese region of Minho. Molecular epidemiological analysis was applied to data from 289 HIV-1-infected individuals followed at the reference hospital of the province of Minho, Portugal, at which isolated viruses had been sequenced between 2000 and 2012. Viruses of the G (29.1%) and B (27.0%) subtypes were the most frequent, followed by recombinant forms (17.6%) and the C (14.5%), F1 (7.3%), and A1 (4.2%) subtypes. Multinomial logistic regression revealed that the odds of being infected with the A1 and F1 subtypes increased over the years compared with those with B, G, or C subtypes or recombinant viruses. As expected, polyphyletic patterns suggesting multiple and old introductions of the B and G subtypes were found. However, transmission clusters of non-B and non-G viruses among native individuals were also found, with the dates of the most recent common ancestor estimated to be in the early 2000s. Our study supports that the HIV-1 subtype diversity in the Portuguese region of Minho is high and has been increasing in a manner that is apparently driven by factors other than immigration and international travel. Infections with A1 and F1 viruses in the region of Minho are becoming established and are mainly found in sexually transmitted clusters, reinforcing the need for more efficacious control measures targeting this infection route.
Maturation of Human Herpesvirus 6A Glycoprotein O Requires Coexpression of Glycoprotein H and Glycoprotein L
Authors: Tang Huamin , Mahmoud Nora F. , Mori Yasuko
Published: February 2015

Glycoprotein O (gO) is conserved among betaherpesviruses, but little is known about the maturation process of gO in human herpesvirus 6 (HHV-6). We found that HHV-6 gO maturation was accompanied by cleavage of its carboxyl terminus and required coexpression of gH and gL, which promoted the export of gO out of the endoplasmic reticulum (ER). Finally, we also found that gO was not required for HHV-6A growth in T cells.
The Retinoblastoma Tumor Suppressor Promotes Efficient Human Cytomegalovirus Lytic Replication
Authors: VanDeusen Halena R. , Kalejta Robert F.
Published: February 2015

The retinoblastoma (Rb) tumor suppressor controls cell cycle, DNA damage, apoptotic, and metabolic pathways. DNA tumor virus oncoproteins reduce Rb function by either inducing Rb degradation or physically disrupting complexes between Rb and its myriad binding proteins. Human cytomegalovirus (HCMV), a betaherpesvirus being investigated for potential roles in human cancers, encodes multiple lytic-phase proteins that inactivate Rb in distinct ways, leading to the hypothesis that reduced Rb levels and/or activity would benefit HCMV lytic infection. Paradoxically, we found that Rb knockdown prior to infection, whether transient or constitutive, impaired HCMV lytic infection at multiple stages, notably viral DNA replication, late protein expression, and infectious virion production. The existence of differentially modified forms of Rb, the temporally and functionally distinct means by which HCMV proteins interact with Rb, and the necessity of Rb for efficient HCMV lytic replication combine to highlight the complex relationship between the virus and this critical tumor suppressor.

IMPORTANCE
Initial work examining viral protein modulation of cell cycle progression and oncogenic transformation revealed that these proteins inactivated the function of cellular tumor suppressor proteins. However, subsequent work, including experiments described here using human cytomegalovirus, demonstrate a more nuanced interaction that includes the necessity of cellular tumor suppressors for efficient viral replication. Understanding the positive impacts that cellular tumor suppressors have on viral infections may reveal new activities of these well-studied yet incompletely understood proteins. The basis for oncolytic viral therapy is the selective replication of viruses in transformed cells in which tumor suppressor function may be compromised. Understanding how tumor suppressors support viral infections may allow for the generation of modified oncolytic viruses with greater selective tumor cell replication and killing.
Oncogenic Human T-Cell Lymphotropic Virus Type 1 Tax Suppression of Primary Innate Immune Signaling Pathways
Authors: Hyun Jinhee , Ramos Juan Carlos , Toomey Ngoc , Balachandran Siddharth , Lavorgna Alfonso , Harhaj Edward , Barber Glen N.
Published: February 2015

Human T-cell lymphotropic virus type I (HTLV-1) is an oncogenic retrovirus considered to be the etiological agent of adult T-cell leukemia (ATL). The viral transactivator Tax is regarded as the oncoprotein responsible for contributing toward the transformation process. Here, we demonstrate that Tax potently inhibits the activity of DEx(D/H) box helicases RIG-I and MDA5 as well as Toll-dependent TIR-domain-containing adapter-inducing interferon-β (TRIF), which function as cellular sensors or mediators of viral RNA and facilitate innate immune responses, including the production of type I IFN. Tax manifested this function by binding to the RIP homotypic interaction motif (RHIM) domains of TRIF and RIP1 to disrupt interferon regulatory factor 7 (IRF7) activity, a critical type I IFN transcription factor. These data provide further mechanistic insight into HTLV-1-mediated subversion of cellular host defense responses, which may help explain HTLV-1-related pathogenesis and oncogenesis.

IMPORTANCE
It is predicted that up to 15% of all human cancers may involve virus infection. For example, human T-cell lymphotropic virus type 1 (HTLV-1) has been reported to infect up to 25 million people worldwide and is the causative agent of adult T-cell leukemia (ATL). We show here that HTLV-1 may be able to successfully infect the T cells and remain latent due to the virally encoded product Tax inhibiting a key host defense pathway. Understanding the mechanisms by which Tax subverts the immune system may lead to the development of a therapeutic treatment for HTLV-1-mediated disease.
A Basic Cluster in the N Terminus of Yellow Fever Virus NS2A Contributes to Infectious Particle Production
Authors: Voßmann Stephanie , Wieseler Janett , Kerber Romy , Kümmerer Beate Mareike
Published: February 2015

The flavivirus NS2A protein is involved in the assembly of infectious particles. To further understand its role in this process, a charged-to-alanine scanning analysis was performed on NS2A encoded by an infectious cDNA clone of yellow fever virus (YFV). Fifteen mutants containing single, double, or triple charged-to-alanine changes were tested. Five of them did not produce infectious particles, whereas efficient RNA replication was detectable for two of the five NS2A mutants (R22A-K23A-R24A and R99A-E100A-R101A mutants). Prolonged cultivation of transfected cells resulted in the recovery of pseudorevertants. Besides suppressor mutants in NS2A, a compensating second-site mutation in NS3 (D343G) arose for the NS2A R22A-K23A-R24A mutant. We found this NS3 mutation previously to be suppressive for the NS2Aα cleavage site Q189S mutant, also deficient in virion assembly. In this study, the subsequently suggested interaction between NS2A and NS3 was proven by coimmunoprecipitation analyses. Using selectively permeabilized cells, we could demonstrate that the regions encompassing R22A-K23A-R24A and Q189S in NS2A are localized to the cytoplasm, where NS3 is also known to reside. However, the defect in particle production observed for the NS2A R22A-K23A-R24A and Q189S mutants was not due to a defect in physical interaction between NS2A and NS3, as the NS2A mutations did not interrupt NS3 interaction. In fact, a region just upstream of R22-K23-R24 was mapped to be critical for NS2A-NS3 interaction. Taken together, these data support a complex interplay between YFV NS2A and NS3 in virion assembly and identify a basic cluster in the NS2A N terminus to be critical in this process.

IMPORTANCE
Despite an available vaccine, yellow fever remains endemic in tropical areas of South America and Africa. To control the disease, antiviral drugs are required, and an understanding of the determinants of virion assembly is central to their development. In this study, we identified a basic cluster of amino acids in the N terminus of YFV NS2A which inhibited virion assembly upon mutation. The defect was rescued by a spontaneously occurring mutation in NS3. Our study proves an interaction between NS2A and NS3, which, remarkably, was maintained for the NS2A mutant in the presence and absence of the NS3 mutation. This suggests a role for other viral and/or cellular proteins in virion assembly. Residues important for YFV virion production reported here only partially coincided with those reported for other flaviviruses, suggesting that the determinants for particle production are virus specific. Reconstruction of a YFV encoding tagged NS2A paves the way to identify further NS2A interaction partners.
Sedimentary record of glacial Lake Missoula along the Clark Fork River from deep to shallow positions in the former lakes
Authors: Smith Larry N. , Hanson Michelle A.
Published: February 2015

Glacial Lake Missoula was repeatedly dammed by the Purcell Trench Lobe of the Cordilleran ice sheet during the last glaciation to maximum altitudes near 4200 ft (1280 m). Studies from outside of the lake basin suggest that the lake filled and drained multiple times in the late Pleistocene. Deposits and landforms within the former glacial lake basin provide evidence for a complex lake-level history that is not well understood for this famous impoundment. At least two general lake phases are evident in the stratigraphy: an earlier phase of catastrophic drainage that was responsible for large-scale dramatic erosional and depositional features, and a later, less-catastrophic, phase responsible for the preservation of fine-grained glaciolacustrine sediments. Features of the earlier lake phase include giant gravel dunes and openwork gravel with anomalously large clasts (erratics). Deposits from the later phase are mostly low-energy glaciolacustrine sediments that record a history of lake-bottom sedimentation and repeated lake-floor exposure.

A focus of this field trip is to look at evidence for the two lake phases as well as evaluate the record of exposure surfaces, and therefore lake-level lowerings, during the second phase at multiple locations in the lake basin. One of the second phase sites is close to a highstand, full basin position in the lake (near Garden Gulch), representing a maximum water depth at this site of ~100 m, whereas others (Rail line and Ninemile) are at lower altitudes in regions that may have been under as much as 300 m of water.

Fine-grained glaciolacustrine sediments are rippled very fine sandy silt and fining-upward sequences of laminated silt and clayey silt of glaciolacustrine origin. Periglacial features, contorted bedding, desiccation, and paleosols in outcrop provide clear evidence of multiple exposure surfaces; each represent a lake-lowering event. Optically stimulated luminescence (OSL or “optical dating”) ages on quartz from the three sections (Ninemile, Rail line, and Garden Gulch) allow for preliminary correlations that suggest approximately the same phase of glacial Lake Missoula sedimentation. The exposure surfaces suggest that the glacial-lake level rose and fell at least 8–12 times to elevations above and below the sections (936–1180 m), filling to within 100 m of full pool (1280 m). Optical dating shows that this occurred after 20 ka and the last inundation of the lake before 13.5 ka. Correlation of specific exposure surfaces throughout the basin will be required to develop a lake-level history.
Neotectonics and geomorphic evolution of the northwestern arm of the Yellowstone Tectonic Parabola
Authors: Ruleman Chester A. , Larsen Mort , Stickney Michael C.
Published: February 2015

The catastrophic Hebgen Lake earthquake of 18 August 1959 (MW7.3) led many geoscientists to develop new methods to better understand active tectonics in extensional tectonic regimes that address seismic hazards. The Madison Range fault system and adjacent Hebgen Lake–Red Canyon fault system provide an intermountain-active tectonic analog for regional analyses of extensional crustal deformation. The Madison Range fault system comprises fault zones (~100 km in length) that have multiple salients and embayments marked by preexisting structures exposed in the footwall. Quaternary tectonic activity rates differ along the length of the fault system, with less displacement to the north. Within the Hebgen Lake basin, the 1959 earthquake is the latest slip event in the Hebgen Lake–Red Canyon fault system and southern Madison Range fault system. Geomorphic and paleoseismic investigations indicate previous faulting events on both fault systems. Surficial geologic mapping and historic seismicity support a coseismic structural linkage between the Madison Range and Hebgen Lake–Red Canyon fault systems.

On this trip, we will look at Quaternary surface ruptures that characterize prehistoric earthquake magnitudes. The one-day field trip begins and ends in Bozeman, and includes an overview of the active tectonics within the Madison Valley and Hebgen Lake basin, southwestern Montana. We will also review geologic evidence, which includes new geologic maps and geomorphic analyses that demonstrate preexisting structural controls on surface rupture patterns along the Madison Range and Hebgen Lake–Red Canyon fault systems.
The Yellowstone and Regal talc mines and their geologic setting in southwestern Montana
Authors: Underwood Sandra J. , Childs John F. , Walby Chad P. , Lynn Helen B. , Wall Zachary S. , Cerino Michael T. , Bartlett Ericka
Published: February 2015

We summarize the geologic settings, generalized geology, and inferred conditions of talc formation for two major deposits in southwestern Montana. Imerys Talc operates the Yellowstone Mine in the Gravelly Range. Barretts Minerals Inc., a subsidiary of Minerals Technologies Incorporated, mines talc from two large deposits—the Regal and the Treasure—in the southern Ruby Range. Talc mineralization in southwestern Montana is associated with hydrothermal alteration of Archean dolomitic marbles along faults in the southern margin of the middle Proterozoic Belt Seaway. Conditions of talc formation appear to have varied across the region and probably range from shallow hot spring systems to connate brine circulation pathways in Belt basin sediments. A road log description of the geology along a loop from Bozeman to Dillon, Montana, to visit both the Yellowstone and Regal talc mines accompanies this paper.
A cohort study of influences, health outcomes and costs of patients’ health-seeking behaviour for minor ailments from primary and emergency care settings
Authors: Watson M C , Ferguson J , Barton G R , Maskrey V , Blyth A , Paudyal V , Bond C M , Holland R , Porteous T , Sach T H , Wright D , Fielding S
Published: February 2015

Objectives

To compare health-related and cost-related outcomes of consultations for symptoms suggestive of minor ailments in emergency departments (EDs), general practices and community pharmacies.

Design

Observational study; prospective cohort design.

Setting

EDs (n=2), general practices (n=6) and community pharmacies (n=10) in a mix of rural/urban and deprived/affluent areas across North East Scotland and East Anglia. Participants Adults (≥18 years) presenting between 09:00 and 18:00 (Monday–Friday) in general practices and 09:00–18:00 (Monday–Saturday) in pharmacies and EDs with ≥1 of the following: musculoskeletal pain; eye discomfort; gastrointestinal disturbance; or upper respiratory tract-related symptoms.

Interventions

Participants completed three questionnaires: baseline (prior to index consultation); satisfaction with index consultation and follow-up (2 weeks after index consultation).

Main outcome measures

Symptom resolution, quality of life, costs, satisfaction and influences on care-seeking behaviour.

Results

377 patients participated, recruited from EDs (81), general practices (162) and community pharmacies (134). The 2-week response rate was 70% (264/377). Symptom resolution was similar across all three settings: ED (37.3%), general practice (35.7%) and pharmacy (44.3%). Mean overall costs per consultation were significantly lower for pharmacy (£29.30 (95% CI £21.60 to £37.00)) compared with general practice (£82.34 (95% CI £63.10 to £101.58)) and ED (£147.09 (95% CI £125.32 to £168.85)). Satisfaction varied across settings and by measure used. Compared with pharmacy and general practice use, ED use was significantly (p<0.001) associated with first episode and short duration of symptom(s), as well as higher levels of perceived seriousness and urgency for seeking care. Convenience of location was the most common reason for choice of consultation setting.

Conclusions

These results suggest similar health-related outcomes and substantially lower costs with pharmacy consultations for minor ailments. Effective strategies are now needed to shift demand for minor ailment management away from EDs and general practices to the community pharmacy setting.