bluuebunny/crossref_metadata_2025 huggingface dataset:
MicroRNA‐155 controls Toll‐like receptor 3‐ and hepatitis C virus‐induced immune responses in the liver
Authors: Jiang M. , Broering R. , Trippler M. , Wu J. , Zhang E. , Zhang X. , Gerken G. , Lu M. , Schlaak J. F.
Published: September 2013

The hepatitis C virus (HCV) establishes persistent infections despite strong activation of the innate immune system through TLR3 and other sensors. Therefore, we analysed regulatory mechanisms of TLR3‐induced immune responses in nonparenchymal liver cells (NPCs). Effects of Interleukin‐10 (IL‐10), transforming growth factor beta (TGF‐β) and immunoregulatory miR‐155 on poly I:C‐activated murine (C57BL/6) Kupffer cells (KC) and sinusoidal endothelial cells (LSEC) were assessed in vitro. NPCs were assayed for inflammatory and antiviral cytokines and T‐cell (Balb/c)‐activating factors. Gene expression of miR‐155, IL‐10, TGF‐β and interferon sensitive genes (ISGs) in biopsies of patients with HCV was determined by qrt‐PCR. TLR3‐induced antiviral activity in murine NPCs was potently suppressed by IL‐10 and TGF‐β which correlated with decreased TLR3 expression and inhibition of NF‐κB and IRF‐3 activation. T‐cell activation, induced by TLR3‐activated NPCs, was also suppressed by IL‐10 and TGF‐β, which was associated with a down‐regulation of CD80 and CD86. Pretreatment with IL‐10 or TGF‐β suppressed TLR3‐induced miR‐155 expression, which itself positively regulated poly I:C‐mediated immune responses, thus counteracting IL‐10 or TGF‐β‐induced immunosuppression. In addition, hepatic expression of miR‐155 was elevated in chronically infected patients with HCV, was associated with an IL‐28B SNP (rs12979860) and was inversely correlated with HCV serum load and ISG expression levels. As miR‐155 is a key regulator of anti‐inflammatory mechanisms that control innate and adaptive hepatic immune responses during HCV infection, miR‐155 based therapies may represent a novel mechanism to control HCV in the future.
Gentlemen first? ‘Broken stick’ modelling reveals sex‐related homing decision date in migrating seabirds
Authors: Thiebot J.‐B. , Authier M. , Trathan P. N. , Bost C.‐A.
Published: September 2013

Technical progress in animal‐borne tracking and movement data analysis has facilitated the understanding of the interplay between successive periods in the life cycle of migratory animals. We investigated how sex differences on the constraints of homing may influence migration to breeding areas in crested penguins (genus Eudyptes). We used a novel approach to infer homing decision date, a precise point in time that translates statistically as a change point in the current distance of the animal to its colony (‘broken stick’ modelling approach, R codes provided here). We applied this approach to geolocation tracking data on migration in three Eudyptes species, from three localities in the southern Indian Ocean (five populations). Sex had a subtle and consistent influence on the temporal activity of the 66 animals during their migratory journey. Males began migration to the breeding localities earlier than females, by an average of 9.1 (range: 4.5–13.5) days. This difference was statistically significant in 4 of 5 populations, and occurred among all species, sites and years surveyed. Our study shows an original application of a recent modelling approach to detect change point in movement data. Our results suggest that sex‐specific constraints related to breeding in migrating animals may also modify activity schedules well before breeding commences.
Chondritic models of 4 Vesta: Implications for geochemical and geophysical properties
Authors: Toplis M. J. , Mizzon H. , Monnereau M. , Forni O. , McSween H. Y. , Mittlefehldt D. W. , McCoy T. J. , Prettyman T. H. , De Sanctis M. C. , Raymond C. A. , Russell C. T.
Published: September 2013

Simple mass‐balance and thermodynamic constraints are used to illustrate the potential geochemical and geophysical diversity of a fully differentiated Vesta‐sized parent body with a eucrite crust (e.g., core size and density, crustal thickness). The results of this analysis are then combined with data from the howardite–eucrite–diogenite (HED) meteorites and the Dawn mission to constrain Vesta's bulk composition. Twelve chondritic compositions are considered, comprising seven carbonaceous, three ordinary, and two enstatite chondrite groups. Our analysis excludesCIandLLcompositions as plausible Vesta analogs, as these are predicted to have a negative metal fraction. Second, theMELTSthermodynamic calculator is used to show that the enstatite chondrites, theCV,CKand L‐groups cannot produce Juvinas‐like liquids, and that even for the other groups, depletion in sodium is necessary to produce liquids of appropriate silica content. This conclusion is consistent with the documented volatile‐poor nature of eucrites. Furthermore, carbonaceous chondrites are predicted to have a mantle too rich in olivine to produce typical howardites and to have Fe/Mn ratios generally well in excess of those of theHEDs. On the other hand, an Na‐depleted H‐chondrite bulk composition is capable of producing Juvinas‐like liquids, has a mantle rich enough in pyroxene to produce abundant howardite/diogenite, and has a Fe/Mn ratio compatible with eucrites. In addition, its predicted bulk‐silicate density is within 100 kg m−3of solutions constrained by data of the Dawn mission. However, oxidation state and oxygen isotopes are not perfectly reproduced and it is deduced that bulk Vesta may contain approximately 25% of aCM‐like component. Values for the bulk‐silicate composition of Vesta and a preliminary phase diagram are proposed.
A Raman spectroscopic study of organic matter in interplanetary dust particles and meteorites using multiple wavelength laser excitation
Authors: Starkey N. A. , Franchi I. A. , Alexander C. M. O'D.
Published: September 2013

Raman spectroscopy was used to investigate insoluble organic matter (IOM) from a range of chondritic meteorites, and a suite of interplanetary dust particles (IDPs). Three monochromatic excitation wavelengths (473 nm, 514 nm, 632 nm) were applied sequentially to assess variations in meteorite and IDP Raman peak parameters (carbon D and G bands) as a function of excitation wavelength (i.e., dispersion). Greatest dispersion occurs in CVs > OCs > CMs > CRs with type 3 chondrites compared at different excitation wavelengths displaying conformable relationships, in contrast to type 2 chondrites. These findings indicate homogeneity in the structural nature of type 3 chondrite IOM, while organic matter (OM) in type 2 chondrites appears to be inherently more heterogeneous. If type 2 and type 3 chondrite IOM shares a common source, then thermal metamorphism may have a homogenizing effect on the originally more heterogeneous OM. IDP Raman G bands fall on an extension of the trend displayed by chondrite IOM, with all IDPs having Raman parameters indicative of very disordered carbon, with almost no overlap with IOM. The dispersion effect displayed by IDPs is most similar to CMs for the G band, but intermediate between CMs and CRs for the D band. The existence of some overlapping Raman features in the IDPs and IOM indicates that their OM may share a common origin, but the IDPs preserve more pristine OM that may have been further disordered by ion irradiation. H, C, and N isotopic data for the IDPs reveal that the disordered carbon in IDPs corresponds with higher δ15N and lower δ13C.
A molecular gut content study of Themisto abyssorum (Amphipoda) from Arctic hydrothermal vent and cold seep systems
Authors: Olsen Bernt Rydland , Troedsson Christofer , Hadziavdic Kenan , Pedersen Rolf B. , Rapp Hans Tore
Published: September 2013

The use of DNA as a marker for prey inside the gut of predators has been instrumental in further understanding of known and unknown interactions. Molecular approaches are in particular useful in unavailable environments like the deep sea. Trophic interactions in the deep sea are difficult to observe in situ, correct deep‐sea experimental laboratory conditions are difficult to obtain, animals rarely survive the sampling, or the study organisms feed during the sampling due to long hauls. Preliminary studies of vent and seep systems in the Nordic Seas have identified the temperate‐cold‐water pelagic amphipod Themisto abyssorum as a potentially important predator in these chemosynthetic habitats. However, the prey of this deep‐sea predator is poorly known, and we applied denaturing high performance liquid chromatography (DHPLC) to investigate the predator–prey interactions of T. abyssorum in deep‐water vent and seep systems. Two deep‐water hydrothermally active localities (The Jan Mayen and Loki's Castle vent fields) and one cold seep locality (The Håkon Mosby mud volcano) in the Nordic Seas were sampled, genomic DNA of the stomachs of T. abyssorum was extracted, and 18S rDNA gene was amplified and used to map the stomach content. We found a wide range of organisms including micro‐eukaryotes, metazoans and detritus. Themisto abyssorum specimens from Loki's Castle had the highest diversity of prey. The wide range of prey items found suggests that T. abyssorum might be involved in more than one trophic level and should be regarded as an omnivore and not a strict carnivore as have previously been suggested.
Unlocking the vault: next‐generation museum population genomics
Authors: Bi Ke , Linderoth Tyler , Vanderpool Dan , Good Jeffrey M. , Nielsen Rasmus , Moritz Craig
Published: September 2013

Natural history museum collections provide unique resources for understanding how species respond to environmental change, including the abrupt, anthropogenic climate change of the past century. Ideally, researchers would conduct genome‐scale screening of museum specimens to explore the evolutionary consequences of environmental changes, but to date such analyses have been severely limited by the numerous challenges of working with the highly degraded DNA typical of historic samples. Here, we circumvent these challenges by using custom, multiplexed, exon capture to enrich and sequence ~11 000 exons (~4 Mb) from early 20th‐century museum skins. We used this approach to test for changes in genomic diversity accompanying a climate‐related range retraction in the alpine chipmunks (Tamias alpinus) in the high Sierra Nevada area of California, USA. We developed robust bioinformatic pipelines that rigorously detect and filter out base misincorporations in DNA derived from skins, most of which likely resulted from postmortem damage. Furthermore, to accommodate genotyping uncertainties associated with low‐medium coverage data, we applied a recently developed probabilistic method to call single‐nucleotide polymorphisms and estimate allele frequencies and the joint site frequency spectrum. Our results show increased genetic subdivision following range retraction, but no change in overall genetic diversity at either nonsynonymous or synonymous sites. This case study showcases the advantages of integrating emerging genomic and statistical tools in museum collection‐based population genomic applications. Such technical advances greatly enhance the value of museum collections, even where a pre‐existing reference is lacking and points to a broad range of potential applications in evolutionary and conservation biology.
From Normality to Normativity
Authors: De Cauwer Stijn
Published: September 2013

In his novel Il conformista, Alberto Moravia explores the dangers of a rigid view on normality. The protagonist, Marcello, is an example of what Georges Canguilhem has called ‘the disease of normality’. An uptight view on normality will produce a form of pathology and violence. Robert Musil describes a similar concern, but his work is a search to find a way to avoid the dangers Moravia depicts. With the writings of Moravia and Musil as our guide, along with the theories of Georges Canguilhem and Guillaume Le Blanc, we shall explore the thin line between normality and pathology.
Discrepancies between explicit and implicit self‐esteem and their relationship to symptoms of depression and mania
Authors: Pavlickova Hana , Turnbull Oliver H. , Bentall Richard P.
Published: September 2013

Objectives

Self‐esteem is a key feature of bipolar symptomatology. However, so far no study has examined the interaction between explicit and implicit self‐esteem in individuals vulnerable to bipolar disorder.

Design

Cross‐sectional design was employed.

Methods

Thirty children of parents with bipolar disorder and 30 offspring of control parents completed Hamilton Rating Scale for Depression, the Bech‐Rafaelson Mania Scale, the Self‐esteem Rating Scale and the Implicit Association Test.

Results

No differences between groups were revealed in levels of explicit or implicit self‐esteem. However, bipolar offspring showed increased levels of symptoms of depression and mania. Furthermore, depressive symptoms were associated with low explicit self‐esteem, whilst symptoms of mania were associated with low implicit self‐esteem. When self‐esteem discrepancies were examined, damaged self‐esteem (i.e., low explicit but high implicit self‐esteem) was associated with depression, whilst no associations between mania and self‐esteem discrepancies were found.

Conclusions

Not only explicit, but also implicit self‐esteem, and the interactions between the two are of relevance in bipolar symptoms. Clinical implications and future research directions are discussed.

Practitioner points

Explicit as well as implicit SE, and particularly their relationship, are relevant for mental health.

Fluctuations in implicit SE may serve as an early indicator for risk of bipolarity.

Psychotherapeutic approaches may be more suitable for one kind of SE challenge than the other.
Are We Luminous?
Authors: Srinivasan Amia
Published: September 2013

Since its appearance over a decade ago, Timothy Williamson's anti‐luminosity argument has come under sustained attack. Defenders of the luminous overwhelmingly object to the argument's use of a certain margin‐for‐error premise. Williamson himself claims that the premise follows easily from a safety condition on knowledge together with his description of the thought experiment. But luminists argue that this is not so: the margin‐for‐error premise either requires an implausible interpretation of the safety requirement on knowledge, or it requires other equally implausible (and soritical) assumptions. In this paper I bolster the margin‐for‐error premise against these attacks by recasting Williamson's own two‐part defence, the first part intended to work on the assumption that there is no constitutive connection between the phenomenal and the doxastic, and the second intended to work without this assumption. Pace various luminists, I argue that the appeals to safety needed for Williamson's two‐part defence (the first in terms of outright belief, the second in terms of degrees of confidence) are plausible. I also argue that all that is needed to generate the margin‐for‐error premise from these safety conditions is an empirical assumption about the kinds of creatures we are: that is, creatures whose beliefs are structured by certain dispositions. By recasting the anti‐luminosity argument in this way, we can understand what is really at stake in the debate about luminosity: that is, whether we are luminous.
Violence and Italian universities during the Renaissance
Authors: Davies Jonathan
Published: September 2013

Historians have recently begun to explore premodern academic violence and this study is the first survey of violence at Italian universities between the fifteenth and the seventeenth centuries. It seeks to address a series of questions. How frequent was violence? What forms did it take? What motivated it? What were the responses of the authorities? Examining these issues increases our understanding of masculinity and academic, social, and national identities in this period. It also throws light on the nature of justice in the Italian states.
Overnight storage of whole blood: cooling and transporting blood at room temperature under extreme temperature conditions
Authors: Thibault L. , Beauséjour A. , Jacques A. , Ducas É. , Tremblay M.
Published: September 2013

Background and Objectives

Many countries allow the overnight storage of whole blood (WB) at ambient temperature. Some countries, such as Canada, also require a rapid cooling of WB with an active cooling system. Given the significant operational constraints associated with current cooling systems, an alternative method for cooling and transporting WB at 20–24°C was evaluated.

Materials and Methods

Phase 22 cooling packs (TCP Reliable Inc., USA) were used in combination with vacuum‐insulated panel (VIP) boxes. Temperature profiles of simulated WB units were studied in extreme temperatures (−35 and 40°C). The quality of blood components prepared using Phase 22 packs and CompoCool‐WB (Fresenius HemoCare, Germany) was studied.

Results

Phase 22 packs reduced the temperature of simulated WB bags from 37 to 24°C in 1·7 ± 0·2 h. Used in combination with VIP boxes, Phase 22 packs maintain the temperature of bags between 20 and 24°C for 15 and 24 h, compared to 2 and 11 h with CompoCool‐WB, when exposed at −35 and 40°C, respectively. The quality of platelet concentrates and plasma was comparable, regardless of the cooling system used. For red blood cell units, per cent haemolysis on day 42 was slightly higher in products prepared after cooling with Phase 22 packs compared to CompoCool‐WB (0·33 ± 0·15% vs. 0·21 ± 0·06%; P < 0·05).

Conclusions

Phase 22 packs combined with VIP boxes are an acceptable alternative to butane‐1,4‐diol cooling systems. This system allows blood manufacturers to transport WB to processing facilities in a broad range of environmental conditions.
Reactivity of Iron/Zirconia Powder in Fluidized Bed Thermochemical Hydrogen Production Reactors
Authors: Al-Raqom F. , Klausner J. F.
Published: September 2013

A fluidized bed reactor has been developed which uses a two-step thermochemical water splitting process with a peak hydrogen production rate of 47 Ncm3/min.gFe at an oxidation temperature of 850 °C. Of particular interest, is that a mixture of iron and zirconia powder is fluidized during the oxidation reaction using a steam mass flux of 58 g/min-cm2. The zirconia powder serves to virtually eliminate iron powder sintering while maintaining a high reaction rate. The iron/zirconia powder is mixed in a ratio of 1:2 by apparent volume and has a mass ratio of 1:1. Both iron and zirconia particles are sieved to sizes ranging from 125 μm to 355 μm. The efficacy of zirconia as a sintering inhibitor was found to be dependent on the iron and zirconia mean particle size, particle size distribution and iron/zirconia apparent volume ratio. At 650 °C, the oxidation of iron powder with a mean particle size of 100 μm and a wide particle size distribution (40–250 μm) mixed with 44 μm zirconia powder with an iron/zirconia apparent volume ratio of 1:1 results in 75–90% sintering. In all cases, when iron is mixed with zirconia, the hydrogen production rate is not affected when compared with the pure iron case assuming an equivalent mass of iron is in the mixture. When iron powder is mixed with zirconia, both with a narrow particle size distribution (125–355 μm), the first oxidation step results in 3–7% sintering when the reactions are carried out at temperatures ranging between 840 and 895 °C. The hydrogen fractional yield is high (94–97%). For subsequent redox reactions, the macroscopic sintering is totally eliminated at 867 and 895 °C, although the hydrogen fractional yield decreases to 27 and 33%, respectively. It is demonstrated that mixing iron with zirconia in an equivalent mass ratio and similar particle size range can eliminate macroscopic sintering in a fluidized bed reactor at elevated temperatures up to 895 °C.
Optimal Control and Forward Dynamics of Human Periodic Motions Using Fourier Series for Muscle Excitation Patterns
Authors: Sharif Shourijeh Mohammad , McPhee John
Published: September 2013

Forward dynamic simulations of a periodic forearm motion were developed in order to explore the efficiency of using a Fourier-series-based parameterization function for muscle excitations within dynamic optimization. The specific objectives of this study were to develop such a simulation and validate the predictions. Several time-integral objective functions, including muscle activation effort and metabolic energy, were used to see the effects of each on the optimal results. For validation, the motion and muscle electromyograms (EMGs) of three adult subjects were captured, where each trial was replicated twice. Fourier-series pattern parameterization was found to be an efficient choice for the muscle excitations in simulating human musculoskeletal dynamics.
Hydrogen Production Via Ethanol Steam Reforming Over Ni/Al2O3 Catalysts: Effect of Ni Loading
Authors: Bshish Ahmed , Yaakob Zahira , Ebshish Ali , Alhasan Fatah H.
Published: September 2013

Catalytic systems play an important role in hydrogen production via ethanol reforming. The effect of Ni loading on the characteristics and activities of Ni/Al2O3 catalysts used in pure ethanol steam reforming are not well-understood. Two series of catalysts with various Ni loadings (6, 8, 10, 12, and 20 wt. %) were prepared by impregnation (IMP) and precipitation (PT) methods and were tested in reforming reactions. The catalysts were characterized by Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), temperature-programmed reduction (TPR), and scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM–EDAX). Powder XRD patterns of all the catalysts exhibited only NiO. Lower Ni loading catalysts were more efficient in H2 production, as evidenced by the finding that a 6 wt. % Ni catalyst, synthesized via the PT method, yielded 3.68 mol H2 per mol ethanol fed. The high surface area and small crystallite size of the low Ni loading catalysts resulted in sufficient dispersion and strong metal-support interactions, which closely related to the high activity of the 6 PT catalyst.
An Analytical Model for Calculating the Workspace of a Flexure Hexapod Nanopositioner
Authors: Shi Hongliang , Su Hai-Jun
Published: September 2013

This paper presents an analytical model for calculating the workspace of a flexure-based hexapod nanopositioner previously built by the National Institute of Standards and Technology (NIST). This nanopositioner is capable of producing high-resolution motions in six degrees of freedom by actuating linear actuators on a planar tri-stage. However, the workspace of this positioner is still unknown, which limits its uses in practical applications. In this work, we seek to derive a kinematic model for predicting the workspace of such kinds of flexure based platforms by assuming that their workspace is mainly constrained by the deformation of flexure joints. We first study the maximum deformation including bending and torsion angles of an individual flexure joint. We then derive the inverse kinematics and calculation of bending and torsion angles of each wire flexure in the overall mechanism with given position of the top platform center of the hexapod nanopositioner. At last, we compare results with finite element models of the entire platform. This model is beneficial for workspace analysis and optimization for design of compliant parallel mechanisms.
Hopf Instabilities in Free Piston Stirling Engines
Authors: Choudhary Farhan , Balachandran Balakumar
Published: September 2013

Free piston Stirling engines (FPSEs) are examples of closed cycle regenerative engines, which can be used to convert thermal energy into mechanical energy. These engines are multidegree-of-freedom dynamical systems, which are designed to operate in a periodic manner. Traditionally, for design purposes, linear models are used and the associated periodic orbits are meta-stable, making the system operations sensitive to disturbances. A preferred operating state would be a stable limit cycle, which can make the system dynamics robust to disturbances. To this end, in this article, it is investigated as to how to engineer Hopf bifurcations of an equilibrium solution in the β and double acting α FPSE configurations that could lead to attracting periodic solutions. Weakly nonlinear analyses are conducted and analytical relations governing the periodic motions are obtained and studied in the vicinity of Hopf bifurcation points. The analytical predictions are confirmed through numerical simulations that are based upon reported engine parameters. The overall analytical-numerical approach pursued here could serve as a tool for using nonlinearity in the design of FPSEs, thereby enhancing the robustness of device operations.
Bifurcation and Chaotic Analysis of Aeroelastic Systems
Authors: Wang Cheng-Chi , Chen Chieh-Li , Yau Her-Terng
Published: September 2013

The dynamic behavior of aeroelastic systems is governed by a complex interaction among inertial, elastic, and aerodynamic forces. To prevent system instability, the interaction among these forces must be properly understood. Accordingly, the present study utilizes the differential transformation method (DTM) to examine the nonlinear dynamic response of a typical aeroelastic system (an aircraft wing) under realistic operating parameters. The system behavior and onset of chaos are interpreted by means of bifurcation diagrams, Poincaré maps, power spectra, and maximum Lyapunov exponent plots. The results reveal the existence of a complex dynamic behavior comprising periodic, quasi-periodic and chaotic responses. It is shown that chaotic motion occurs at specific intervals for different trailing edge and leading edge angles with changing initial conditions. The results presented in this study provide a useful guideline for the design of aircraft wings and confirm the validity of the DTM method as a design and analysis tool for aeroelastic systems in general.
An Industrially Validated Method for Weld Load Balancing in Multi Station Sheet Metal Assembly Lines
Authors: Segeborn Johan , Segerdahl Daniel , Ekstedt Fredrik , Carlson Johan S. , Andersson Mikael , Carlsson Anders , Söderberg Rikard
Published: September 2013

Sheet metal assembly is investment intense. Therefore, the equipment needs to be efficiently utilized. The balancing of welds has a significant influence on achievable production rate and equipment utilization. Robot line balancing is a complex problem, where each weld is to be assigned to a specific station and robot, such that line cycle time is minimized. Industrial robot line balancing has been manually conducted in computer aided engineering (CAE)-tools based on experience and trial and error rather than mathematical methods. However, recently an automatic method for robot line balancing was proposed by the authors. To reduce robot coordination cycle time losses, this method requires identical reach ability of all line stations. This limits applicability considerably since in most industrial lines, reach ability differs over the stations to further line reach ability and flexibility. Therefore, in this work we propose a novel generalized simulation-based method for automatic robot line balancing that allows any robot positioning. It reduces the need for robot coordination significantly by spatially separating the robot weld work loads. The proposed method is furthermore successfully demonstrated on automotive stud welding lines, with line cycle times lower than that of the corresponding running production programs. Moreover, algorithm central processing unit (CPU)-times are mere fractions of the lead times of existing CAE-tools.
Characterization of Real Eigenvalues in Linear Viscoelastic Oscillators and the Nonviscous Set
Authors: Lázaro Mario , Pérez-Aparicio José L.
Published: September 2013

In structural dynamics, energy dissipative mechanisms with nonviscous damping are characterized by their dependence on the time-history of the response velocity, which is mathematically represented by convolution integrals involving hereditary functions. The widespread Biot damping model assumes that such functions are exponential kernels, which modify the eigenvalues' set so that as many real eigenvalues (named nonviscous eigenvalues) as kernels are added to the system. This paper is focused on the study of a mathematical characterization of the nonviscous eigenvalues. The theoretical results allow the bounding of a set belonging to the real negative numbers, called the nonviscous set, constructed as the union of closed intervals. Exact analytical solutions of the nonviscous set for one and two exponential kernels and approximated solutions for the general case of N kernels are developed. In addition, the nonviscous set is used to build closed-form expressions to compute the nonviscous eigenvalues. The results are validated with numerical examples covering single and multiple degree-of-freedom systems where the proposed method is compared with other existing one-step approaches available in the literature.
Suppression of Friction-Induced Bending Vibrations in a Flexible Disk Sliding in Contact With a Rigid Surface
Authors: Ryzhik Boris
Published: September 2013

The paper describes an instability mechanism in a friction unit comprising a rotating flexible annular disk pressed to a rigid surface on the whole outer circumference. It is shown that for such a system, sliding friction forces set up a feedback between the orthogonal bending eigenmodes of the disk with the same form but different angular orientation. Due to axisymmetry, these modes have the same eigenfrequency. The feedback between the vibration modes with the same frequency leads to appearance of the circulation terms in the equations of motion and to instability. As a measure to suppress squeal, special apertures in the disk are suggested. The goal is to detach the paired eigenfrequencies to stabilize the system. The positioning of the apertures is discussed. The instability mechanism is investigated on the simple analytical model. More detailed finite-element analysis confirms the analytical prediction about the influence of the friction and axisymmetry on the instability and enables to prove the measures against friction induced vibrations.
On the Optimized Design of Broaching Tools
Authors: Hosseini A. , Kishawy H. A.
Published: September 2013

Among the cutting tools that are utilized in industry broaching tools are the most expensive ones. Unlike other machining operations such as milling and turning in which a cutting tool can be used for producing a variety of shapes, the broaching tools are uniquely designed depending on the desired profile to be produced on the workpiece. Consequently, the shape of broaching tools may be altered from one case to the others. This shape can be a simple keyway or a complicated fir tree on a turbine disk. Hence, a proper design of the broaching tools has the highest priority in broaching operation. Every single feature of these expensive tools must be accurately designed to increase productivity, promote part quality and reduce manufacturing cost. A geometric model of the cutting tool and a predictive force model to estimate the cutting forces are two fundamental requirements in simulation of any machining operation. This paper presents a geometric model for the broaching tools and a predictive force model for broaching operations. The broaching tooth is modeled as a cantilevered beam and the cutting forces are predicted based on the energy spent in the cutting system. A design procedure has been also developed for identification of the optimized tool geometry aiming to achieve maximum metal removal rate (MRR) by considering several physical and geometrical constraints.
Temperature-Dependent Modulus of Metals Based on Lattice Vibration Theory
Authors: Su Honghong , Fang Xufei , Feng Xue , Yan Bo
Published: September 2013

Fundamentally understanding the temperature-dependent modulus is the key issue for materials serving in high temperature environments. This paper proposes a model based on lattice vibration theory to predict the temperature-dependent modulus with respect to isothermal and isentropic assumption. The thermal vibration free energy is expressed as a function of the two independent scalars from the strain tensor and temperature. By using the Einstein theory, we present the analytical expression for the temperature-dependent Young's modulus, bulk modulus, shear modulus, and Poisson's ratio. The theoretical prediction agrees well with the experimental data. The proposed model is further degenerated to Wachtman's empirical equation and provides the physical meaning to the parameters in Wachtman's equation.
Material Behavior Modeling in Machining Simulation of 7075-T651 Aluminum Alloy
Authors: Li Shuhui , Hou Bo
Published: September 2013

Accurate modeling of workpiece material behavior in machining is critical to analyze and design a process. The workpiece material behavior in the machining process involves dynamic flow stress and damage/fracture behavior, which are very difficult to be determined. In this study, the extended split Hopkinson pressure bar (SHPB) test is conducted to determine the dynamic flow stress curves of 7075-T651 aluminum alloy, which enables the strain, strain rate and the temperature obtained in the test to approach that in the cutting condition. A damage criterion under the typical stress state of orthogonal cutting is established to reflect the material damage initiation in primary shear zone. The damage criterion parameters of 7075-T651 alloy are determined by comparing the numerical and experimental results of the proposed inner high-pressure piercing fracture test. The orthogonal cutting test and simulation of 7075-T651 alloy are conducted. It is demonstrated that the determined flow stress and the established damage criterion produces realistic process outputs in agreement with experimental results.
Ohmic contacts fabricated on moderately doped p-type GaAs by sputtering deposition and a laser-firing process
Authors: Boronat Alfredo , Silvestre Santiago , Orpella Albert
Published: September 2013

A novel approach is used to achieve ohmic contacts on moderately doped p-type GaAs substrates. A laser-firing process is used instead of the conventional annealing step. The morphology of the crater created by the laser-firing process and the electrical response of the metal–semiconductor contact are characterized.
A novel approach for direct reconstruction of parametric images for myocardial blood flow from PET imaging
Authors: Su Kuan‐Hao , Yen Tzu‐Chen , Fang Yu‐Hua Dean
Published: September 2013

Purpose:

The aim of this study is to develop and evaluate a novel direct reconstruction method to improve the signal‐to‐noise ratio (SNR) of parametric images in dynamic positron‐emission tomography (PET), especially for applications in myocardial perfusion studies.

Methods:

Simulation studies were used to test the performance in SNR and computational efficiency for different methods. The NCAT phantom was used to generate simulated dynamic data. Noise realization was performed in the sinogram domain and repeated for 30 times with four different noise levels by varying the injection dose (ID) from standard ID to 1/8 of it. The parametric images were calculated by (1) three direct methods that compute the kinetic parameters from the sinogram and (2) an indirect method, which computes the kinetic parameter with pixel‐by‐pixel curve fitting in image space using weighted least‐squares. The first direct reconstruction maximizes the likelihood function using trust‐region‐reflective (TRR) algorithm. The second approach uses tabulated parameter sets to generate precomputed time‐activity curves for maximizing the likelihood functions. The third approach, as a newly proposed method, assumes separable complete data to derive the M‐step for maximizing the likelihood.

Results:

The proposed method with the separable complete data performs similarly to the other two direct reconstruction methods in terms of the SNR, providing a 5%–10% improvement as compared to the indirect parametric reconstruction under the standard ID. The improvement of SNR becomes more obvious as the noise level increases, reaching more than 30% improvement under 1/8 ID. Advantage of the proposed method lies in the computation efficiency by shortening the time requirement to 25% of the indirect approach and 3%–6% of other direct reconstruction methods.

Conclusions:

With results provided from this simulation study, direct reconstruction of myocardial blood flow shows a high potential for improving the parametric image quality for clinical use.
Risk Factors for Campylobacteriosis in Two Washington State Counties with High Numbers of Dairy Farms
Authors: Davis Margaret A. , Moore Danna L. , Baker Katherine N. K. , French Nigel P. , Patnode Marianne , Hensley Joni , MacDonald Kathryn , Besser Thomas E.
Published: September 2013

Campylobacteriosis is a frequently reported, food-borne, human bacterial disease that can be associated with ruminant reservoirs, although public health messages primarily focus on poultry. In Washington State, the two counties with the highest concentrations of dairy cattle also report the highest incidences of campylobacteriosis. Conditional logistic regression analysis of case-control data from both counties found living or working on a dairy farm (odds ratio [OR], 6.7 [95% confidence interval [CI], 1.7 to 26.4]) and Hispanic ethnicity (OR, 6.4 [95% CI, 3.1 to 13.1]) to have the strongest significant positive associations with campylobacteriosis. When the analysis was restricted to residents of one county, Hispanic ethnicity (OR, 9.3 [95% CI, 3.9 to 22.2]), contact with cattle (OR, 5.0 [95% CI, 1.3 to 19.5]), and pet ownership (OR, 2.6 [95% CI, 1.1 to 6.3]) were found to be independent risk factors for disease.
Campylobacter jejuni
isolates from human (
n
= 65), bovine (
n
= 28), and retail poultry (
n
= 27) sources from the same counties were compared using multilocus sequence typing. These results indicated that sequence types commonly found in human isolates were also commonly found in bovine isolates. These findings suggest that, in areas with high concentrations of dairy cattle, exposure to dairy cattle may be more important than food-borne exposure to poultry products as a risk for campylobacteriosis.
Evaluation of Pneumococcal Serotyping by Multiplex PCR and Quellung Reactions
Authors: Richter Sandra S. , Heilmann Kristopher P. , Dohrn Cassie L. , Riahi Fathollah , Diekema Daniel J. , Doern Gary V.
Published: September 2013

Screening of 1,750 pneumococcal isolates for common serotypes by PCR was followed by Quellung reaction analysis of PCR-negative isolates with a comparison to the conventional (Quellung reaction only) approach. PCR agreed with Quellung reaction results for 99% of isolates. The sequential PCR/Quellung reaction algorithm is accurate and more cost-effective than the conventional approach.
Incidence of Inducible Clindamycin Resistance in Staphylococcus pseudintermedius from Dogs
Authors: Gold Randi M. , Lawhon Sara D.
Published: September 2013

Clindamycin is increasingly used to treat canine pyoderma. Eight of 608Staphylococcus pseudintermediusisolates were positive for inducible clindamycin resistance by double-disk diffusion testing and PCR detection ofermB.Staphylococcus pseudintermediusisolates that are erythromycin resistant but clindamycin susceptible byin vitroantimicrobial susceptibility testing should be tested for inducible clindamycin resistance.
Identification of Novel Host Factors via Conserved Domain Search: Cns1 Cochaperone Is a Novel Restriction Factor of Tombusvirus Replication in Yeast
Authors: Lin Jing-Yi , Nagy Peter D.
Published: September 2013

A large number of host-encoded proteins affect the replication of plus-stranded RNA viruses by acting as susceptibility factors. Many other cellular proteins are known to function as restriction factors of viral infections. Previous studies with tomato bushy stunt tombusvirus (TBSV) in a yeast model host have revealed the inhibitory function of TPR (tetratricopeptide repeat) domain-containing cyclophilins, which are members of the large family of host prolyl isomerases, in TBSV replication. In this paper, we tested additional TPR-containing yeast proteins in a cell-free TBSV replication assay and identified the Cns1p cochaperone for heat shock protein 70 (Hsp70) and Hsp90 chaperones as a strong inhibitor of TBSV replication. Cns1p interacted with the viral replication proteins and inhibited the assembly of the viral replicase complex and viral RNA synthesis
in vitro
. Overexpression of Cns1p inhibited TBSV replication in yeast. The use of a temperature-sensitive (TS) mutant of Cns1p in yeast revealed that at a semipermissive temperature, TS Cns1p could not inhibit TBSV replication. Interestingly, Cns1p and the TPR-containing Cpr7p cyclophilin have similar inhibitory functions during TBSV replication, although some of the details of their viral restriction mechanisms are different. Our observations indicate that TPR-containing cellular proteins could act as virus restriction factors.
High-Avidity and Potently Neutralizing Cross-Reactive Human Monoclonal Antibodies Derived from Secondary Dengue Virus Infection
Authors: Tsai Wen-Yang , Lai Chih-Yun , Wu Yi-Chieh , Lin Hong-En , Edwards Carolyn , Jumnainsong Amonrat , Kliks Srisakul , Halstead Scott , Mongkolsapaya Juthathip , Screaton Gavin R. , Wang Wei-Kung
Published: September 2013

The envelope (E) protein of dengue virus (DENV) is the major target of neutralizing antibodies (Abs) and vaccine development. Previous studies of human dengue-immune sera reported that a significant proportion of anti-E Abs, known as group-reactive (GR) Abs, were cross-reactive to all four DENV serotypes and to one or more other flaviviruses. Based on studies of mouse anti-E monoclonal antibodies (MAbs), GR MAbs were nonneutralizing or weakly neutralizing compared with type-specific MAbs; a GR response was thus not regarded as important for vaccine strategy. We investigated the epitopes, binding avidities, and neutralization potencies of 32 human GR anti-E MAbs. In addition to fusion loop (FL) residues in E protein domain II, human GR MAbs recognized an epitope involving both FL and bc loop residues in domain II. The neutralization potencies and binding avidities of GR MAbs derived from secondary DENV infection were stronger than those derived from primary infection. GR MAbs derived from primary DENV infection primarily blocked attachment, whereas those derived from secondary infection blocked DENV postattachment. Analysis of the repertoire of anti-E MAbs derived from patients with primary DENV infection revealed that the majority were GR, low-avidity, and weakly neutralizing MAbs, whereas those from secondary infection were primarily GR, high-avidity, and potently neutralizing MAbs. Our findings suggest that the weakly neutralizing GR anti-E Abs generated from primary DENV infection become potently neutralizing MAbs against the four serotypes after secondary infection. The observation that the dengue immune status of the host affects the quality of the cross-reactive Abs generated has implications for new strategies for DENV vaccination.
Gamma Interferon Regulates Contraction of the Influenza Virus-Specific CD8 T Cell Response and Limits the Size of the Memory Population
Authors: Prabhu Nayana , Ho Adrian W. , Wong Kenneth H. S. , Hutchinson Paul Edward , Chua Yen Leong , Kandasamy Matheswaran , Lee Debbie C. P. , Sivasankar Baalasubramanian , Kemeny David Michael
Published: September 2013

The factors that regulate the contraction of the CD8 T cell response and the magnitude of the memory cell population against localized mucosal infections such as influenza are important for generation of efficient vaccines but are currently undefined. In this study, we used a mouse model of influenza to demonstrate that the absence of gamma interferon (IFN-γ) or IFN-γ receptor 1 (IFN-γR1) leads to aberrant contraction of antigen-specific CD8 T cell responses. The increased accumulation of the effector CD8 T cell population was independent of viral load. Reduced contraction was associated with an increased fraction of CD8 T cells expressing the interleukin-7 receptor (IL-7R) at the peak of the response, resulting in enhanced numbers of memory/memory precursor cells in IFN-γ−/−and IFN-γR−/−compared to wild-type (WT) mice. Blockade of IL-7 within the lungs of IFN-γ−/−mice restored the contraction of influenza virus-specific CD8 T cells, indicating that IL-7R is important for survival and is not simply a consequence of the lack of IFN-γ signaling. Finally, enhanced CD8 T cell recall responses and accelerated viral clearance were observed in the IFN-γ−/−and IFN-γR−/−mice after rechallenge with a heterologous strain of influenza virus, confirming that higher frequencies of memory precursors are formed in the absence of IFN-γ signaling. In summary, we have identified IFN-γ as an important regulator of localized viral immunity that promotes the contraction of antigen-specific CD8 T cells and inhibits memory precursor formation, thereby limiting the size of the memory cell population after an influenza virus infection.
Mechanistic Insights into the Enhancement of Adeno-Associated Virus Transduction by Proteasome Inhibitors
Authors: Mitchell Angela M. , Samulski R. Jude
Published: September 2013

Proteasome inhibitors (e.g., bortezomib, MG132) are known to enhance adeno-associated virus (AAV) transduction; however, whether this results from pleotropic proteasome inhibition or off-target serine and/or cysteine protease inhibition remains unresolved. Here, we examined recombinant AAV (rAAV) effects of a new proteasome inhibitor, carfilzomib, which specifically inhibits chymotrypsin-like proteasome activity and no other proteases. We determined that proteasome inhibitors act on rAAV through proteasome inhibition and not serine or cysteine protease inhibition, likely through positive changes late in transduction.
Chandipura Virus Induces Neuronal Death through Fas-Mediated Extrinsic Apoptotic Pathway
Authors: Ghosh Sourish , Dutta Kallol , Basu Anirban
Published: September 2013

Chandipura virus (CHPV; genusVesiculovirus, familyRhabdoviridae) is an emerging tropical pathogen with a case fatality rate of 55 to 75% that predominantly affects children in the age group of 2 to 16 years. Although it has been established as a neurotropic virus causing encephalitis, the molecular pathology leading to neuronal death is unknown. The present study elucidates for the first time the mechanism of cell death in neurons after CHPV infection that answers the basic cause of CHPV-mediated neurodegeneration. Through various cell death assaysin vitroandin vivo, a relationship between viral replication within neuron and neuronal apoptosis has been established. We report that expression of CHPV phosphoprotein increases up to 6 h postinfection and diminishes thereafter in neuronal cell lines, signifying the replicative phase of CHPV. Various analyses conducted during the investigation established that CHPV-infected neurons are undergoing apoptosis through an extrinsic pathway mediated through the Fas-associated death domain (FADD) following activation of caspase-8 and -3 and prominent cleavage of poly(ADP-ribose) polymerase (PARP). Knocking down the expression of caspase-3, the final executioner of apoptosis, in a neuronal cell line by endoribonuclease-prepared small interfering RNA (siRNA) validated its pivotal role in CHPV-mediated neurodegeneration by showing reduction in apoptosis after CHPV infection.