bluuebunny/crossref_metadata_2025 huggingface dataset:
Sympathetic nerve fiber repulsion: testing norepinephrine, dopamine, and 17β‐estradiol in a primary murine sympathetic neurite outgrowth assay
Authors: Klatt Susanne , Fassold Alexander , Straub Rainer H.
Published: July 2012

Loss of sympathetic nerve fibers (SNFs) occurs in inflamed tissue; and select semaphorins, upregulated during inflammation, stimulate repulsion/loss of SNFs. However, it is unknown whether other factors released locally in inflamed tissue, such as norepinephrine, dopamine, and 17β‐estradiol, are also repellent. In order to study the effects of hormones on SNF repulsion, an SNF outgrowth assay was used. The repellent activity of semaphorins 3C was weaker than of semaphorin 3F. Tumor necrosis factor α (TNF‐α) repelled nerve fibers with moderate to strong effects (from 0–100% repulsion). High concentrations of dopamine and norepinephrine (10−6 M) induced weak but significant nerve fiber repulsion (up to 20%). Norepinephrine at 10−8 M was comparable with 10−6 M at inducing nerve fiber outgrowth. Stimulation with low concentrations of 17β‐estradiol (10−10 M, but not 10−8 M) repelled SNFs. These results demonstrate that not only specific axon guidance molecules, such as semaphorins 3F and 3C, but also hormonal factors and TNF‐α influence SNF repulsion and outgrowth.
Sex steroids, immune system, and parasitic infections: facts and hypotheses
Authors: Nava‐Castro Karen , Hernández‐Bello Romel , Muñiz‐Hernández Saé , Camacho‐Arroyo Ignacio , Morales‐Montor Jorge
Published: July 2012

It has been widely reported that the incidence and the severity of natural parasitic infections are different between males and females of several species, including humans. This sexual dimorphism involves a distinct exposure of males and females to various parasite infective stages, differential effects of sex steroids on immune cells, and direct effects of these steroids on parasites, among others. Typically, for a large number of parasitic diseases, the prevalence and intensity is higher in males than females; however, in several parasitic infections, males are more resistant than females. In the present work, we review the effects of sex hormones on immunity to protozoa and helminth parasites, which are the causal agents of several diseases in humans, and discuss the most recent research related to the role of sex steroids in the complex host–parasite relationship.
Peripheral immune system and neuroimmune communication impairment in a mouse model of Alzheimer's disease
Authors: Giménez‐Llort Lydia , Maté Ianire , Manassra Rashed , Vida Carmen , De la Fuente Mónica
Published: July 2012

Neurodegenerative diseases such as Alzheimer's disease (AD) can be understood in the context of the aging of neuroimmune communication. Although the contribution to AD of the immune cells present in the brain is accepted, the role of the peripheral immune system is less well known. The present review examines the behavior and the function and redox state of peripheral immune cells in a triple‐transgenic mouse model (3×Tg‐AD). These animals develop both beta‐amyloid plaques and neurofibrillary tangles with a temporal‐ and regional‐specific profile that closely mimics their development in the human AD brain. We have observed age and sex‐related changes in several aspects of behavior and immune cell functions, which demonstrate premature aging. Lifestyle strategies such as physical exercise and environmental enrichment can improve these aspects. We propose that the analysis of the function and redox state of peripheral immune cells can be a useful tool for measuring the progression of AD.
Effects of plasmalogens on systemic lipopolysaccharide‐induced glial activation and β‐amyloid accumulation in adult mice
Authors: Katafuchi Toshihiko , Ifuku Masataka , Mawatari Shiro , Noda Mami , Miake Kiyotaka , Sugiyama Masaaki , Fujino Takehiko
Published: July 2012

Neuroinflammation essentially involves an activation of glial cells as the cause/effect of neurodegenerative diseases such as Alzheimer's disease (AD). Plasmalogens (Pls) are glycerophospholipids constituting cellular membranes and play significant roles in membrane fluidity and cellular processes like vesicular fusion and signal transduction. Intraperitoneal (i.p.) injection of lipopolysaccharide (LPS, 250 μg/kg) for 7 days resulted in the morphological changes and increase in number of Iba‐1+ microglia showing neuroinflammation in the adult mouse hippocampus. The LPS‐induced activation of glial cells was significantly attenuated by i.p. pretreatment with Pls dissolved in corn oil. In addition, systemic injection of LPS induced Aβ1–16+ neurons in the hippocampus were also abolished by application of Pls. Finally, contents of Pls in the hippocampus decreased after LPS injection, and the reduction was suppressed by administration of Pls. These findings suggest an antiamyloidogenic effect of Pls, implicating a possible therapeutic application of Pls against AD.
TGF‐β neutralization abrogates the inhibited DHEA production mediated by factors released from M. tuberculosis–stimulated PBMC
Authors: D’Attilio Luciano , Bozza Verónica V. , Santucci Natalia , Bongiovanni Bettina , Dídoli Griselda , Radcliffe Stella , Besedovsky Hugo , del Rey Adriana , Bottasso Oscar , Bay María Luisa
Published: July 2012

Supernatants (SN) from cultures of peripheral blood mononuclear cells (PBMC) of tuberculosis (TB) patients inhibit dehydroepiandrosterone (DHEA) secretion by the adrenal cell line NCI‐H295R. To analyze whether TGF‐β is involved in this effect, SN of PBMC from healthy controls or patients with severe TB infections, stimulated or not with Mycobacterium tuberculosis (Mtb SN), were added to adrenal cells under basal conditions or following stimulation with forskolin. Cortisol and DHEA concentrations were evaluated in supernatants of the adrenal cells cultured with or without the addition of anti‐TGF‐β. Treatment with Mtb SN from TB inhibited DHEA production, and this effect was reversed when SN were treated with anti‐TGF‐β. The increase in cortisol production induced by SN from TB patients was not affected by TGF‐β neutralization. Mediators released during the anti‐TB immune response differentially modulate steroid production by adrenal cells, and TGF‐β is a cytokine implicated in the inhibition of DHEA production observed in TB.
The neuroimmune connection interferes with tissue regeneration and chronic inflammatory disease in the skin
Authors: Peters Eva M.J. , Liezmann Christiane , Klapp Burghard F. , Kruse Johannes
Published: July 2012

Research over the past decades has revealed close interactions between the nervous and immune systems that regulate peripheral inflammation and link psychosocial stress with chronic somatic disease. Besides activation of the sympathetic and the hypothalamus–pituitary–adrenal axis, stress leads to increased neurotrophin and neuropeptide production in organs at the self–environment interface. The scope of this short review is to discuss key functions of these stress mediators in the skin, an exemplary stress‐targeted and stress‐sensitive organ. We will focus on the skin's response to acute and chronic stress in tissue regeneration and pathogenesis of allergic inflammation, psoriasis, and skin cancer to illustrate the impact of local stress‐induced neuroimmune interaction on chronic inflammation.
Increasing the validity of experimental models for depression
Authors: Dzirasa Kafui , Covington Herbert E.
Published: July 2012

Major depressive disorder (MDD) is a central nervous system disorder characterized by the culmination of profound disturbances in mood and affective regulation. Animal models serve as a powerful tool for investigating the neurobiological mechanisms underlying this disorder; however, little standardization exists across the wide range of available modeling approaches most often employed. This review will illustrate some of the most challenging obstacles faced by investigators attempting to associate depressive‐like behaviors in rodents with symptoms expressed in MDD. Furthermore, a novel series of depressive‐like criteria based on correlating behavioral endophenotypes, novel in vivo neurophysiological measurements, and molecular/cellular analyses within multiple brain are proposed as a potential solution to overcoming this barrier. Ultimately, linking the neurophysiological and cellular/biochemical actions that contribute to the expression of a defined MDD‐like syndrome will dramatically extend the translational value of the most valid animal models of MDD.
Factors affecting early psychiatric intervention for patients with first‐episode psychosis in Japan
Authors: Hagi Noriko , Takamura Mitsuyuki , Yokoyama Kazuhito
Published: July 2012

Aim

The present study aimed to clarify the factors affecting early psychiatric intervention for patients with first‐episode psychosis in Japan.

Methods

A postal questionnaire survey was conducted in 346 members of the Association of Family of Psychosis Patients, in Mie, Japan.

Results

The questionnaire was completed by 138 respondents. The mean interval between a suspected first episode of psychosis and the first visit to a medical institution was 18.4 months (SD: 40.0, range: 0–336 months). Forty‐five respondents consulted a family member first and required a mean duration of 9.8 months (SD: 11.2) before their first visit; this was significantly shorter than those who did not. Eighteen respondents consulted their class teacher at school first and required a mean duration of 40.2 months (SD: 63.0) before their first visit; this was significantly longer (P < 0.05) than those who did not. When loss of sleep or appetite was present, the mean duration before their first visit was 9.3 months (SD: 12.1), which was significantly shorter (P < 0.05) than the time required by those who did not. Logistic regression analysis using the first episode‐first visit interval as an independent variable, and independent variables such as age, gender of the patient and family member, and loss of sleep, revealed that variables relating to the respondent's notion about the psychosis were mitigating factors (e.g. ‘prejudice‐causing’ and ‘nothing to do with me’).

Conclusion

Prejudice towards psychosis and poor awareness about mental illnesses are two factors that may affect early psychiatric intervention.
TANF’s 15th Anniversary and the Great Recession: are Low‐Income Mothers Celebrating Upward Economic Mobility?
Authors: Katz Sheila
Published: July 2012

This article examines the impact of welfare reform for the upward economic mobility of low‐income families at the fifteenth anniversary of the Temporary Assistance for Needy Families (TANF) program. The reformed policy was based on assumptions about participating families’ morality and encouraged states to move families off welfare through work and marriage without considering whether they were still poor. TANF was also implemented during an economic boom. Today, the US economy is suffering from the effects of the Great Recession, with many fearing a double dip recession. Poverty rates rose during the last 3 years and are currently above 15 percent. For the first time since 1996, the welfare rolls are increasing in many states. Welfare reform’s ‘work first’ approach did not create lasting upward economic mobility for low‐income families. As an alternative, I explore how higher education for welfare mothers will create opportunities for lasting upward mobility, even in times of recession.
Training on a new, portable, simple simulator transfers to performance of complex bronchoscopy procedures
Authors: Krogh Charlotte Loumann , Konge Lars , Bjurström Johanna , Ringsted Charlotte
Published: July 2012

Introduction

Virtual‐reality (VR) simulation provides a safe and effective learning environment prior to practicing on patients. However, existing bronchoscopy simulators are expensive and not easily portable.

Objectives

The aim of this study was to assess the effect of self‐directed training on a new, portable, simple simulator measured by transfer of skills to performance of more complex bronchoscopy procedures on an advanced VR simulator.

Methods

Twenty medical students participated in the study. After a general introduction to bronchoscopy, they were randomised into two groups, receiving either self‐directed bronchoscopy training using a portable, simple simulator or no manual training. Subsequently, all participants were tested on complex scenarios in an advanced VR simulator using a validated bronchoscopy quality test. Bronchoscopy quality scores were compared using independent samples t‐test and correlated with a previously established pass‐fail standard.

Results

The intervention group spent an average of 71‐min training on the new simulator. The intervention group performed significantly better than the control group, mean bronchoscopy quality score 0.55 [standard deviation (SD) 0.16] vs 0.36 (SD 0.10), P = 0.005, effect size = 1.47. Eight out of 10 participants in the intervention group passed the test compared with only 1 out of 10 in the control group.

Conclusion

The effect of a brief, self‐directed training session using a portable, simple simulator was substantial and transferred to performance of more complex skills.
|SE|S|AM|E| Barcode: NGS‐oriented software for amplicon characterization – application to species and environmental barcoding
Authors: PIRY S. , GUIVIER E. , REALINI A. , MARTIN J.‐F.
Published: July 2012

Progress in NGS technologies has opened up new opportunities for characterizing biodiversity, both for individual specimen identification and for environmental barcoding. Although the amount of data available to biologist is increasing, user‐friendly tools to facilitate data analysis have yet to be developed. Our aim, with |SE|S|AM|E| Barcode, is to provide such support through a unified platform. The sequences are analysed through a pipeline that (i) processes NGS amplicon runs, filtering markers and samples, (ii) builds reference libraries and finally (iii) identifies (barcodes) the sequences in each amplicon from the reference library. We use a simulated data set for specimen identification and a recently published data set for environmental barcoding to validate the method. The results obtained are consistent with the expected characterizations (in silico and previously published, respectively). |SE|S|AM|E| Barcode and its documentation are freely available under the Creative Commons Attribution‐NonCommercial‐ShareAlike 3.0 Unported Licence for Windows and Linux from http://www1.montpellier.inra.fr/CBGP/NGS/.
Studies in African Cyperaceae 35. Kyllinga carinalaevis sp. nov. from west tropical Africa
Authors: Lye Kåre Arnstein , Mesterházy Attila
Published: July 2012

A minute new species of Kyllinga, i.e. K. carinalaevis Lye & Mesterházy, from Benin in west tropical Africa is described. It is one of three or four annual species of the genus, and the characters separating it from two other annual species are given. The species is ephemeral and occurs in a vegetation type which belongs to a Nanocyperion association. The species is probably critically endangered as it was found in a single locality out of the numerous sites that have been investigated in Benin in recent years.
Effects of hepatitis B e‐antigen on recurrence of hepatitis B‐related hepatocellular carcinoma after curative resection: A meta‐analysis
Authors: Qu Li‐Shuai , Zhu Jing , Chen Hong , Jin Fei , Ni Run‐Zhou , Lu Cui‐Hua
Published: July 2012

Aim:  The impact of hepatitis B e‐antigen (HBeAg) on recurrence of hepatocellular carcinoma (HCC) after curative resection remains controversial. This meta‐analysis aimed to determine whether the presence of HBeAg influenced the recurrence of HCC after curative resection.

Methods:  We performed a meta‐analysis including six studies (a total of 865 patients) to assess the effect of HBeAg on recurrence of HCC after curative resection. The pooled odds ratios (OR) were calculated using a random or fixed effects model. PUBMED, MEDLINE, EMBASE and the Cochrane Database were searched for articles published from 1990 to March 2012. Sensitivity analysis and publication bias estimate were also performed to evaluate the potential risk bias in the overall results of pooled analysis.

Results:  Our results showed that the presence of HBeAg significantly increased the overall HCC recurrence risk after curative resection (OR = 1.63, 95% confidence interval (CI) = 1.11–2.40; P = 0.01). Pooled data from three studies on the risk of early recurrence among HBeAg positive patients compared with HBeAg negative patients showed an increased risk of early recurrence (OR = 1.50, 95% CI = 1.02–2.19; P = 0.04). However, there was no significant difference in late HCC recurrence between HBeAg positive and negative patients (OR = 1.17, 95% CI = 0.62–2.19; P = 0.62).

Conclusion:  The present study suggested that HBeAg positive patients had a significantly higher risk of early recurrence after curative resection of HCC.
Imperiled Femininity: The Dismembering of Citizenship in Northern Mexico
Authors: Haney Charlotte
Published: July 2012

Abstract

This article examines how historical constructions of Mexican citizenship are implicated in women's current performances of femininity in Chihuahua City. Throughout much of Mexican history, women's rights to life and bodily integrity did not inhere within their own persons but were extensions of the rights of their fathers and husbands. Women living outside male protection had no guarantee of security, and those living within such protection were only guaranteed security from men outside of their relationships of dependency. The following work argues that the legacy of dependent citizenship has created a “bodies politic,” which structures the current system of impunity for gendered violence, and that these structures continue to have an impact on the reimagining of femininity. Drawing on 13 months of fieldwork spent investigating which performances of femininity women most associated with security; this research examines the quotidian strategies through which women are negotiating their need and/or desire to expand upon such performances with their continued desire for security in the increasingly dangerous environment of Northern Mexico.
Inmigración, política y protesta popular contra la explotación laboral en Buenos Aires – Argentina
Authors: Betrisey Débora
Published: July 2012

La crisis económica y política desatada en Argentina durante el año 2001 genera movimientos políticos populares donde hombres y mujeres de diversas clases sociales y orígenes nacionales (argentinos, bolivianos, peruanos, paraguayos, etc.) establecen un vínculo, hasta entonces difícil y poco probable, para realizar un trabajo de reivindicación conjunto. El objetivo del presente trabajo es estudiar las formas culturales que la lucha contra la explotación laboral ha tomado en los talleres textiles de Buenos Aires durante los últimos años. Particularmente, analizo aquellos movimientos llevados a cabo por los integrantes de una asamblea barrial ubicada en Parque Avellaneda, en la que participan un importante número de mujeres de origen boliviano. Estos talleres se caracterizan por las condiciones de pobreza y precariedad laboral que ofrecen a sus trabajadoras. Para ello situamos la temática de las prácticas políticas y los procesos organizativos de los sectores populares en los marcos más amplios de las relaciones de hegemonía, atendiendo a las subjetividades de los diferentes agentes sociales que participan en dichos movimientos y su forma de contrarrestar las interpelaciones dominantes.
Cultivating Votes in Rural Chile
Authors: COUYOUMDJIAN JUAN PABLO , LONDREGAN JOHN BENEDICT
Published: July 2012

In Chile's two‐member legislative districts we show there are two groups of swing voters, one group for the first seat won by the governing coalition, another for the second. We build a model that allows us to identify the relative prevalence of these voters across communities. Using data on the allocation of discretionary agricultural loans, we find that communities with relatively many voters pivotal for the first seat receive more loans than they otherwise would have, but we find no systematic advantage for districts that are pivotal for the second seat.
Geochemistry of intermediate olivine‐phyric shergottite Northwest Africa 6234, with similarities to basaltic shergottite Northwest Africa 480 and olivine‐phyric shergottite Northwest Africa 2990
Authors: FILIBERTO Justin , CHIN Emily , DAY James M. D. , FRANCHI Ian A. , GREENWOOD Richard C. , GROSS Juliane , PENNISTON‐DORLAND Sarah C. , SCHWENZER Susanne P. , TREIMAN Allan H.
Published: July 2012

Abstract— The newly found meteorite Northwest Africa 6234 (NWA 6234) is an olivine (ol)‐phyric shergottite that is thought, based on texture and mineralogy, to be paired with Martian shergottite meteorites NWA 2990, 5960, and 6710. We report bulk‐rock major‐ and trace‐element abundances (including Li), abundances of highly siderophile elements, Re‐Os isotope systematics, oxygen isotope ratios, and the lithium isotope ratio for NWA 6234. NWA 6234 is classified as a Martian shergottite, based on its oxygen isotope ratios, bulk composition, and bulk element abundance ratios, Fe/Mn, Al/Ti, and Na/Al. The Li concentration and δ7Li value of NWA 6234 are similar to that of basaltic shergottites Zagami and Shergotty. The rare earth element (REE) pattern for NWA 6234 shows a depletion in the light REE (La‐Nd) compared with the heavy REE (Sm‐Lu), but not as extreme as the known “depleted” shergottites. Thus, NWA 6234 is suggested to belong to a new category of shergottite that is geochemically “intermediate” in incompatible elements. The only other basaltic or ol‐phyric shergottite with a similar “intermediate” character is the basaltic shergottite NWA 480. Rhenium‐osmium isotope systematics are consistent with this intermediate character, assuming a crystallization age of 180 Ma. We conclude that NWA 6234 represents an intermediate compositional group between enriched and depleted shergottites and offers new insights into the nature of mantle differentiation and mixing among mantle reservoirs in Mars.
40Ar‐39Ar age of Northwest Africa 091: More evidence for a link between L chondrites and fossil meteorites
Authors: WEIRICH J. R. , SWINDLE T. D. , ISACHSEN C. E.
Published: July 2012

Abstract—Most40Ar‐39Ar ages of L chondrites record an event at approximately 500 Ma, indicating a large collisional impact at that time. However, there is a spread in ages from 400 to 600 Ma in these meteorites that is greater than the analytical uncertainty. Identification of, and correction for, trapped Ar in a few L chondrites has given an age of 470 ± 6 Ma. This age coincides with Ordivician fossil meteorites that fell to Earth at 467 ± 2 Ma. As these fossil meteorites were originally L chondrites, the apparent conclusion is that a large impact sent a flood of L chondrite material to Earth, while material that remained on the L chondrite parent body was strongly heated and reset. We have reduced40Ar‐39Ar data for Northwest Africa 091 using various techniques that appear in the literature, including identification and subtraction of trapped Ar. These techniques give a range of ages from 455 to 520 Ma, and show the importance of making accurate corrections. By using the most straightforward technique to identify and remove a trapped Ar component (which is neither terrestrial nor primordial), an40Ar‐39Ar age of 475 ± 6 Ma is found for Northwest Africa 091, showing a temporal link to fossil meteorites. In addition, high temperature releases of Northwest Africa 091 contain evidence for a second trapped component, and subtraction of this component indicates a possible second collisional impact at approximately 800 Ma. This earlier age coincides with40Ar‐39Ar ages of some H and L chondrites, and lunar samples.
Antifibrosis effects of triterpene acids of Eriobotrya japonica (Thunb.) Lindl. leaf in a rat model of bleomycin-induced pulmonary fibrosis
Authors: Yang Yaru , Huang Yan , Huang Cheng , Lv Xiongwen , Liu Liping , Wang Yuanyuan , Li Jun
Published: July 2012

Objective

The aim of this study was to investigate the prophylactic effect and some mechanisms of action of triterpene acids of loquat (TAL) on bleomycin A5-induced pulmonary fibrosis rats.

Methods

A model of pulmonary fibrosis was induced by injecting rats with a single dose of bleomycin A5 (5 mg/kg) into the trachea. From the second day, rats in the preventive groups were treated with TAL (50, 150 or 450 mg/kg) or dexamethasone (1.2 mg/kg). On the 28th day after medication, the rats were killed and haematoxylin-eosin or masson staining was used to evaluate the degree of pulmonary fibrosis. Tumour necrosis factor-α (TNF-α) and transforming growth factor-β1 (TGF-β1) levels in alveolar macrophage culture supernatant were detected by ELISA. The mRNA expression of TNF-α and TGF-β1 in alveolar macrophage was observed by RT-PCR.

Key findings

Lung histopathological examination showed TAL could ameliorate the structure of the lung and alleviate fibrogenesis. At the same time, TAL (150 or 450 mg/kg dose group) could reduce the expression of TNF-α and TGF-β1 in alveolar macrophage of rats with pulmonary fibrosis at either the protein or mRNA level.

Conclusions

TAL had a positive prophylactic effect on lung fibrosis, which might have been related to its reduction on TNF-α or TGF-β1 expression in the alveolar macrophage of pulmonary fibrosis rats.
A Physics-Based Friction Model and Integration to a Simple Dynamical System
Authors: Eriten M. , Polycarpou A. A. , Bergman L. A.
Published: July 2012

Dynamical modeling and simulation of mechanical structures containing jointed interfaces require reduced-order fretting models for efficiency. The reduced-order models in the literature compromise both accuracy and the physical basis of the modeling procedure, especially with regard to interface contact and friction modeling. Recently, physics-based fretting models for nominally flat-on-flat contacts, including roughness effects, have been developed and validated on individual (isolated) mechanical lap joints (Eriten et al., 2011, “Physics-Based Modeling for Fretting Behavior of Nominally Flat Rough Surfaces,” Int. J. Solids Struct., 48(10), pp. 1436-1450). These models follow a “bottom up” modeling approach; utilizing the micromechanics of sphere-on-flat fretting contact (asperity scale), and statistical summation to model flat-on-flat contacts at the macroscale. Since these models are physical, the effects of surface roughness, contact conditions, and material properties on fretting and dynamical response of the jointed interfaces can be studied. The present work illustrates an example of how the physics-based models can be incorporated into studies of the dynamics of jointed structures. A comparison with friction models existing in the literature is also provided.
Forced Vibrations of Supercritically Transporting Viscoelastic Beams
Authors: Ding Hu , Zhang Guo-Ce , Chen Li-Qun , Yang Shao-Pu
Published: July 2012

This study focuses on the steady-state periodic response of supercritically transporting viscoelastic beams. In the supercritical speed range, forced vibrations are investigated for traveling beams via the multiscale analysis with a numerical confirmation. The forced vibration is excited by the spatially uniform and temporally harmonic vibration of the supporting foundation. A nonlinear integro-partial-differential equation is used to determine steady responses. The straight equilibrium configuration bifurcates in multiple equilibrium positions at supercritical translating speeds. The equation is cast in the standard form of continuous gyroscopic systems via introducing a coordinate transform for nontrivial equilibrium configuration. The natural frequencies and modes of the supercritically traveling beams are analyzed via the Galerkin method for the linear standard form with space-dependent coefficients under the simply supported boundary conditions. Based on the natural frequencies and modes, the method of multiple scales is applied to the governing equation to determine steady-state responses. To confirm results via the method of multiple scales, a finite difference scheme is developed to calculate steady-state response numerically. Quantitative comparisons demonstrate that the approximate analytical results have rather high precision. Numerical results are also presented to show the contributions of foundation vibration amplitude, viscoelastic damping, and nonlinearity to the response amplitude for the first and the second mode.
Enforcing Nodes to Suppress Vibration Along a Harmonically Forced Damped Euler-Bernoulli Beam
Authors: Cha Philip D. , Rinker Jennifer M.
Published: July 2012

In this paper, properly tuned damped absorbers are used to suppress excess vibration anywhere along an arbitrarily supported, damped Euler-Bernoulli beam during forced harmonic excitations. This vibration suppression is achieved by enforcing distinct nodes, or points of zero vibration, at desired locations along the beam. Instead of directly solving for the absorber parameter, which is highly computationally intensive, an efficient method is developed whereby the restoring forces exerted by the damped absorbers are first determined using Gaussian elimination. These restoring forces are then used to tune the parameters of the damped oscillators. Numerical experiments show that by inducing nodes at the appropriate locations, a region of nearly zero vibration amplitudes can be enforced, effectively quenching vibration in that segment of the beam.
Analytical Approximations to Conservative Oscillators With Odd Nonlinearity Using the Variational Iteration Method
Authors: Khosrozadeh A. , A. Hajabasi M. , R. Fahham H.
Published: July 2012

In this article, a new technique is introduced for establishing analytical approximate solutions to conservative oscillators with strong odd nonlinearity using the variational iteration method and the Fourier series. The illustrated examples show that only a few iterations can provide very accurate approximate solutions for the whole range of oscillation amplitude even for longer time ranges.
Rolling Condition and Gyroscopic Moments in Curve Negotiations
Authors: Shabana Ahmed A. , Hamper Martin B. , O’Shea James J.
Published: July 2012

In vehicle system dynamics, the effect of the gyroscopic moments can be significant during curve negotiations. The absolute angular velocity of the body can be expressed as the sum of two vectors; one vector is due to the curvature of the curve, while the second vector is due to the rate of change of the angles that define the orientation of the body with respect to a coordinate system that follows the body motion. In this paper, the configuration of the body in the global coordinate system is defined using the trajectory coordinates in order to examine the effect of the gyroscopic moments in the case of curve negotiations. These coordinates consist of arc length, two relative translations, and three relative angles. The relative translations and relative angles are defined with respect to a trajectory coordinate system that follows the motion of the body on the curve. It is shown that when the yaw and roll angles relative to the trajectory coordinate system are constrained and the motion is predominantly rolling, the effect of the gyroscopic moment on the motion becomes negligible and, in the case of pure rolling and zero yaw and roll angles, the generalized gyroscopic moment associated with the system degrees of freedom becomes identically zero. The analysis presented in this investigation sheds light on the danger of using derailment criteria that are not obtained using laws of motion and, therefore, such criteria should not be used in judging the stability of railroad vehicle systems. Furthermore, the analysis presented in this paper shows that the roll moment, which can have a significant effect on the wheel/rail contact forces, depends on the forward velocity in the case of curve negotiations. For this reason, roller rigs that do not allow for the wheelset forward velocity cannot capture these moment components and, therefore, should not be used in the analysis of curve negotiations. A model of a suspended railroad wheelset is used in this investigation to study the gyroscopic effect during curve negotiations.
Volumetric Modeling and Experimental Validation of Normal Contact Dynamic Forces
Authors: Boos Michael , McPhee John
Published: July 2012

A volumetric contact dynamics model has been proposed for the purpose of generating reliable and rapid simulations of contact dynamics. Forces and moments between bodies in contact can be expressed in terms of the volume of interference between the undeformed geometries. This allows for the modeling of contact between complex geometries and relatively large contact surfaces, while being computationally less expensive than finite element methods. However, the volumetric model requires experimental validation. Models for simple geometries in contact have been developed for stationary and dynamic contact, and an apparatus has been developed to experimentally validate these models. This paper focuses on validation of the normal contact models. Measurements of forces and displacements will be used to identify the parameters related to the normal force, i.e., the volumetric stiffness and hysteretic damping factor for metallic surfaces. The experimental measurements are compared with simulated results to assess the validity of the volumetric model.
Wavelet Method for a Class of Fractional Klein-Gordon Equations
Authors: Hariharan G.
Published: July 2012

Wavelet analysis is a recently developed mathematical tool in applied mathematics. A wavelet method for a class of space-time fractional Klein–Gordon equations with constant coefficients is proposed, by combining the Haar wavelet and operational matrix together and efficaciously dispersing the coefficients. The behavior of the solutions and the effects of different values of fractional order α are graphically shown. The fundamental idea of the Haar wavelet method is to convert the fractional Klein–Gordon equations into a group of algebraic equations, which involves a finite number of variables. The examples are given to demonstrate that the method is effective, fast, and flexible; in the meantime, it is found that the difficulties of using the Daubechies wavelets for solving the differential equation, which need to calculate the correlation coefficients, are avoided.
Real-Time Transient Soot and NOx Virtual Sensors for Diesel Engine Using Neuro-Fuzzy Model Tree and Orthogonal Least Squares
Authors: Johri Rajit , Salvi Ashwin , Filipi Zoran
Published: July 2012

Diesel engine combustion and emission formation is highly nonlinear and thus creates a challenge related to engine diagnostics and engine control with emission feedback. This paper presents a novel methodology to address the challenge and develop virtual sensing models for engine exhaust emission. These models are capable of predicting transient emissions accurately and are computationally efficient for control and optimization studies. The emission models developed in this paper belong to the family of hierarchical models, namely the “neuro-fuzzy model tree.” The approach is based on divide-and-conquer strategy, i.e., to divide a complex problem into multiple simpler subproblems, which can then be identified using a simpler class of models. Advanced experimental setup incorporating a medium duty diesel engine is used to generate training data. Fast emission analyzers for soot and NOx provide instantaneous engine-out emissions. Finally, the engine-in-the-loop is used to validate the models for predicting transient particulate mass and NOx.
Numerical Analysis of Panel Flutter on Inertial Manifolds With Delay
Authors: Mei Guanhua , Zhang Jiazhong , Wang Zhuopu
Published: July 2012

Inertial manifolds with delay (IMD) are applied to the numerical analysis for two-dimensional and three-dimensional panel flutter problems in order to demonstrate their high efficiency in continuous dynamic systems or systems with infinite dimensions. First, Von Kármán's large deformation theory and the first-order piston theory are used to model the system, and a set of nonlinear partial differential equations is obtained. Then, the nonlinear Galerkin method based on IMD is introduced to approach the original infinite dimensional dynamic system, and some expressions with time delay are proposed to reveal the interactions between the higher modes and lower modes. As a result, the degrees-of-freedom of the system are reduced, and computing time can be saved remarkably. Finally, the dynamic behaviors of the system are simulated numerically to make a detailed comparison between IMD and the traditional Galerkin method (TGM). Finally, a conclusion can be drawn that IMD could reduce the computation time up to 7–50%, keeping the same accuracy, and thus its high efficiency is proved. Moreover, the method presented can be extended and applied to other dissipative dynamic systems with large degrees-of-freedom.
Particle Number Emissions of Nonroad Diesel Engines of Various Ages
Authors: Niemi Seppo , Ekman Krister , Nousiainen Pekka
Published: July 2012

Over the last two decades, gaseous and particle mass emissions of new diesel engines have been reduced effectively and progressively in response to the emissions legislation and due to the applied new technologies. There is, however, increasing concern about whether the engine modifications, while improving combustion and reducing emissions, have increased the number emissions of ultrafine and nanoparticles. So far, emissions regulations have solely been based on particulate matter (PM) mass measurements, not on particle number. Nanoparticles, however, form a major part of the PM emissions, but they do not considerably contribute to the PM mass and cannot be seen as a problem, if only PM mass is determined. Therefore, there is increasing interest in expanding the scope of the regulations to also include particle number emissions, e.g., Euro VI for on-road engines. The PM number limit will also be enforced for nonroad engines slightly later. Thus, more information is required about the particle number emissions themselves, but also about the effects of the engine technology on them. Wall-flow diesel particulate filters reduce the particle number very effectively within the entire particle size range. Nevertheless, in order to keep the filter as small as possible and to lessen the need for regeneration, the engine-out PM number should also be minimized. If the diesel particulate filters (DPFs) could be left out or replaced by a simpler filter, there would be greater freedom of space utilization or cost savings in many nonroad applications. This might be realized in installations where the engine is tuned at high raw NOx and a selective catalytic reduction (SCR) system is adopted for NOx reduction. However, it is not self-evident that new engine technologies would reduce the PM number emissions sufficiently. In this study, particle number emissions were analyzed in several nonroad diesel engines, representing different engine generations and exploiting different emissions reduction technologies: four- or two-valve heads, exhaust gas recirculation, different injection pressures and strategies, etc. All engines were turbocharged, intercooled, direct-injection nonroad diesel engines. Most engines used common-rail fuel injection technology. Comparisons were, however, also performed with engines utilizing either a distributor-type or an in-line fuel injection pump to see the long-term development of the particle number emissions. In this paper, the PM number emissions of nine nonroad diesel engines are presented and compared. Gaseous exhaust emissions and fuel consumption figures are also provided.
Optimal Gas-Turbine Design for Hybrid Solar Power Plant Operation
Authors: Spelling James , Laumert Björn , Fransson Torsten
Published: July 2012

A dynamic simulation model of a hybrid solar gas-turbine power plant has been developed, allowing determination of its thermodynamic and economic performance. In order to examine optimum gas-turbine designs for hybrid solar power plants, multiobjective thermoeconomic analysis has been performed, with two conflicting objectives: minimum levelized electricity costs and minimum specific CO2 emissions. Optimum cycle conditions: pressure-ratio, receiver temperature, turbine inlet temperature and flow rate, have been identified for a 15 MWe gas-turbine under different degrees of solarization. At moderate solar shares, the hybrid solar gas-turbine concept was shown to provide significant water and CO2 savings with only a minor increase in the levelized electricity cost.
Decision Methods for Design: Insights from Psychology
Authors: Katsikopoulos Konstantinos V.
Published: July 2012

This work aims at stimulating constructive conversation about decision methods in engineering design by using insights from psychology. I point out that any decision method has two components: coherence, which refers to internal consistency (do design choices satisfy a logical axiom?) and correspondence, which refers to external effectiveness (does a design concept satisfy a functional requirement?). Some researchers argue for “rational” methods such as multi-attribute utility theory, whereas others argue for “heuristics” such as the Pugh process, and the coherence/correspondence distinction can clarify this debate in two ways. First, by analyzing statements in the design literature, I argue that the debate is essentially about different strategies for achieving correspondence: Multi-attribute utility theory aims at achieving coherence with the expectation that coherence will imply correspondence, whereas the Pugh process aims at directly achieving correspondence. Second, I propose a new research question for design: “Under what conditions does achieving coherence imply achieving correspondence?”
Study of the Planar Rocking-Block Dynamics With Coulomb Friction: Critical Kinetic Angles
Authors: Zhang Hongjian , Brogliato Bernard , Liu Caishan
Published: July 2012

The objective of this paper is to show, through the planar rocking block example, that kinetic angles play a fundamental role in multiple impact with friction. Even in the presence of Coulomb friction, a critical kinetic angle θcr is exhibited that allows one to split the blocks into two main classes: slender blocks with a kinetic angle larger than θcr, and flat blocks with a kinetic angle smaller than θcr. The value of θcr varies with the friction value, but it is independent of the restitution coefficient (normal dissipation). Numerical results are obtained using a multiple impact law recently introduced by the authors. Some comparisons between numerical and experimental results that validate the used model and numerical scheme are presented. However, this paper is mainly based on numerical simulations.
Effect of Shield-Can on Dynamic Response of Board-Level Assembly
Authors: Yu Da , Kwak Jae , Park Seungbae , Chung Soonwan , Yoon Ji-Young
Published: July 2012

In order to protect the electronic components of electronic devices on a printed circuit board (PCB) against electromagnetic radiation, a conductive shield-can or box is normally attached to the PCB covering the electronic components. In particular, handheld electronic devices are prone to be subjected to drop impact. This means that the products would experience a significant amount of out-of-plane deformation along the PCB, which may cause stresses eventually resulting in solder joint failures. The attached shield-can could provide additional mechanical strength and minimize the out-of-plane deformation, especially where the electronic package is located. In this study, both the dynamic responses of the PCB and the characteristic life of solder joints with different shield-can designs were investigated, which are seldom explored by other researchers. In the board-level drop tests, a noncontact full-field optical measurement technique, digital image correlation (DIC) with images taken by stereo-high-speed cameras, was used to obtain full-field displacement data showing the dynamic responses of the PCB during the drop impact. PCBs with a fine ball grid array (FBGA) package were prepared with various types of shield-can attached. From the experimental results the effects of different shield-can types, varying in shape and size on the dynamic responses of the PCB, were analyzed. In addition, the number of drops to failure for each shield-can was also recorded by an event detector. Using ANSYS/LS-DYNA, an accurately validated finite element model has been developed. Then the stress analysis could be performed in order to study the failure mechanism by finding the maximum tensile stress of the solder joints during the drop impact and correlate the stress results with the characteristic life of solder joint.
Origin of electrical signals for plasma etching end point detection: Comparison of end point signals and electron density
Authors: Sobolewski Mark A. , Lahr David L.
Published: July 2012

Electrical signals are used for end point detection in plasma etching, but the origin of the electrical changes observed at end point is not well understood. As an etch breaks through one layer and exposes an underlayer, the fluxes and densities of etch products and reactants in the gas phase will change. The resulting perturbation in gas composition may alter the plasma electron density, which in turn may affect the electrical signals. Alternatively, changes in substrate electrical properties or surface properties, such as work function or emitted electron yield, may be involved. To investigate these effects, experiments were performed in a radio-frequency (rf)-biased, inductively coupled reactor, during CF4/Ar plasma etching of silicon dioxide films on silicon substrates. A complete set of electrical parameters, for the bias as well as the inductive source, was measured and compared. The most useful end point signal was found to be the fundamental rf bias impedance, which decreases when the oxide is removed. A simultaneous increase in plasma electron density was measured by a wave cutoff probe. Analytical sheath models indicate that the measured change in electron density accounts for nearly all of the impedance decrease. The change in electron density can in turn be explained by the effects of etch products or reactants on gas composition. In contrast, electrons emitted from the wafer surface play at most a minor role in the changes in electron density and impedance observed at end point.
La2O3 gate insulators prepared by atomic layer deposition: Optimal growth conditions and MgO/La2O3 stacks for improved metal-oxide-semiconductor characteristics
Authors: Suzuki Takuya , Kouda Miyuki , Ahmet Parhat , Iwai Hiroshi , Kakushima Kuniyuki , Yasuda Tetsuji
Published: July 2012

The authors investigated the optimal growth conditions for atomic layer deposition of La2O3 using tris(iso-propylcyclopentadienyl) lanthanum, La(iPrCp)3, and H2O, and identified two necessary conditions for achieving self-limiting growth: A low growth temperature (Ts) of 150 °C–175 °C and an extremely long purging after the H2O feed. Low Ts was also preferable for improving the electrical properties of the metal-oxide-semiconductor devices such as the dielectric constant (k), leakage current, and effective mobility. As for the H2O feed time, a long feed resulted in increased interface-trap density, while a short feed resulted in increased leakage. An H2-plasma treatment inserted after the thin-La2O3 (0.5 nm) film growth reduced the leakage current by 3 orders of magnitude compared to the control sample. An MgO capping on the La2O3 remarkably increased the effective k value; however, it degraded the effective mobility. Transmission electron microscopy indicated that the k-value improvement by the MgO capping is due to suppression of La-silicate formation.