bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular phylogenetics of Pimpinella and allied genera (Apiaceae), with emphasis on Chinese native species, inferred from nrDNA ITS and cpDNA intron sequence data
Authors: Wang Zhi‐Xin , Downie Stephen R. , Tan Jin‐Bo , Liao Chen‐Yang , Yu Yan , He Xing‐Jin
Published: December 2013

The genus Pimpinella comprises about 150 species, making it among the largest genera in Apiaceae subfamily Apioideae. It is also a widespread and taxonomically complex group. Previous molecular phylogenetic studies of Pimpinella have focused primarily on its Turkish, African and Malagasy congeners, while resolution of relationships among the approximately 44 species of Pimpinella native to China remains largely obscure, as is the proper circumscription of the genus. In this study, phylogenetic analyses of nrDNA ITS and cpDNA rps16 intron and rpl16 intron sequences were used to assess relationships among Pimpinella species and their closest allies, with emphasis on those species of Pimpinella native to China. We included 122 accessions in the ITS analysis, representing 62 species of Pimpinella of which 26 are native to China, and 54 accessions in the cpDNA and combined molecular analyses, the latter representing 20 species of Pimpinella native to China. The phylogenies inferred from cpDNA intron sequences are highly consistent with those inferred using ITS data. In all analyses, Pimpinella is resolved as non‐monophyletic, yet the monophyly of a Pimpinella‘core group’ in tribe Pimpinelleae is strongly supported. Most Chinese native Pimpinella species fall within this core group; the other Chinese species examined appear in four other tribes within the subfamily. For all Chinese taxa, we consider relevant cytological, morphological, palynological, or phytogeographical data supporting their phylogenetic placements. The new combination Spuriopimpinella arguta (Diels) X. J. He & Z. X. Wang is proposed.
Thriving in long‐term care facilities: instrument development, correspondence between proxy and residents' self‐ratings and internal consistency in the Norwegian version
Authors: Bergland Ådel , Kirkevold Marit , Sandman Per‐Olof , Hofoss Dag , Vassbø Tove , Edvardsson David
Published: December 2013

Aims

To develop an instrument for measuring thriving among residents in long‐term care facilities, to assess the correspondence between proxy ratings and self‐report and the internal consistency of the Norwegian version.

Background

The instrument was developed from the life‐world concept of thriving and thereby has a different theoretical basis than existing ‘dementia related’ quality‐of‐life instruments. Thriving relates the experience of older persons to the place where they live. Proxy instruments need to be developed for residents in long‐term care facilities who are not able to report their subjective experiences.

Design

Instrument development using cross‐sectional survey design.

Methods

The instrument was developed in three versions (resident, family and staff) from a theory on thriving. Forty‐eight triads consisting of a resident, family member and primary nurse from 12 Norwegian nursing homes participated. Data collection took place between March–December 2011. Inter‐rater agreement between the groups was assessed by Cohen's kappa coefficient (weighted). Internal consistency was evaluated by Cronbach's alpha. Homogeneity was explored through item‐total correlations.

Results

Agreement between residents, family members and staff was poor or fair (<0·41) in six of 38 items. These items were excluded. The 32‐items instrument had satisfactory Cronbach's alpha values in each of the three samples and satisfactory homogeneity as item‐total correlations was substantial without being excessive and thus indicated that items were measuring the same construct.

Conclusion

The instrument appears to have internal consistency and enable reliable proxy measures of the thriving construct. Further psychometric assessment including checking for possible item redundancy is needed.
Use of Artificial Neural Network for Industrial Prediction of Final Temperature of Chicken Carcasses
Authors: Silveira Christian L. , Belledeli Bernardo D. , Soares Monica B. A. , Treichel Helen , Mazutti Marcio A.
Published: December 2013

In this work, an artificial neural network (ANN) was used to predict the final temperature of chicken carcasses in an industrial scale. For this purpose, temperatures of chicken carcasses were obtained in a slaughterhouse at the end of the cooling process. The variables considered to influence the temperature of carcasses were average carcass weight, prechiller and chillers velocities, prechiller and chillers average temperatures, the absence or presence of bubbles in prechiller and chiller and bubbles intensity, which were considered as input for the ANN. For training and validation of the feed forward neural network, the above inputs were combined to minimize the weighted sum of the squares of the residues, being tested 10 transfer functions, three training algorithms and two different architectures. The best result was obtained using an ANN composed of two hidden layer (10 nodes in each layer), radial bias as transfer function and gradient descent backpropagation algorithm for training. Using this architecture, the regression coefficient was 0.9265. Even with many variables affecting the industrial cooling process of the chicken carcasses, the ANN developed showed satisfactory fitting of the final temperature of chicken carcasses. This model can be further used for optimization purposes, improving the process quality of chicken carcasses as well as process profitability.

Practical Application

The model used in this study can be further used for control and optimization purposes, improving the process quality of chicken carcasses as well as process profitability.
Understanding and Meeting the Needs of Women in the Postpartum Period: The Perinatal Maternal Health Promotion Model
Authors: Fahey Jenifer O. , Shenassa Edmond
Published: December 2013

A new model for the care of women in the postpartum focuses on the development of life skills that promote complete well‐being. The year following childbirth is a time of significant transition for women. In addition to the physiologic changes associated with the postpartum period, a woman undergoes marked psychosocial changes as she transitions into a motherhood role, reestablishes relationships, and works to meet the physical and emotional needs of her infant and other family members. It is a time when women are vulnerable to health problems directly related to childbirth and to compromised self‐care, which can manifest in the development or reestablishment of unhealthy behaviors such as smoking and a sedentary lifestyle. In addition to long‐term implications for women, compromised maternal health in the postpartum period is associated with suboptimal health and developmental outcomes for infants. Maternal health experts have called for a change in how care is provided for women in the postpartum period. This article presents the rationale for a health promotion approach to meeting the needs of women in the postpartum period and introduces the Perinatal Maternal Health Promotion Model. This conceptual framework is built around a definition of maternal well‐being that asserts that health goes beyond merely the absence of medical complications. In the model, the core elements of a healthy postpartum are identified and include not only physical recovery but also the ability to meet individual needs and successfully transition into motherhood. These goals can best be achieved by helping women develop or strengthen 4 key individual health‐promoting skills: the ability to mobilize social support, self‐efficacy, positive coping strategies, and realistic expectations. While the model focuses on the woman, the health promotion approach takes into account that maternal health in this critical period affects and is affected by her family, social network, and community. Clinical implications of the model are addressed, including specific health promotion strategies that clinicians can readily incorporate into antepartum and postpartum care.
Toward gene therapy for growth hormone deficiency via salivary gland expression of growth hormone
Authors: Racz GZ , Zheng C , Goldsmith CM , Baum BJ , Cawley NX
Published: December 2013

Objectives

Salivary glands are useful targets for gene therapeutics. After gene transfer into salivary glands, regulated secretory pathway proteins, such as human growth hormone, are secreted into saliva, whereas constitutive secretory pathway proteins, such as erythropoietin, are secreted into the bloodstream. Secretion of human growth hormone (hGH) into the saliva is not therapeutically useful. In this study, we attempted to redirect the secretion of transgenic hGH from the saliva to the serum by site‐directed mutagenesis.

Materials and Methods

We tested hGH mutants first in vitro with AtT20 cells, a model endocrine cell line that exhibits polarized secretion of regulated secretory pathway proteins. Selected mutants were further studied in vivo using adenoviral‐mediated gene transfer to rat submandibular glands.

Results

We identified two mutants with differences in secretion behavior compared to wild‐type hGH. One mutant, ΔN1–6, was detected in the serum of transduced rats, demonstrating that expression of this mutant in the salivary gland resulted in its secretion through the constitutive secretory pathway.

Conclusion

This study demonstrates that mutagenesis of therapeutic proteins normally destined for the regulated secretory pathway may result in their secretion via the constitutive secretory pathway into the circulation for potential therapeutic benefit.
Seropositivity of HPV 16 E6 and E7 and the risk of oral cancer
Authors: Wong GR , Ha KO , Himratul‐Aznita WH , Yang YH , Wan Mustafa WM , Yuen KM , Abraham MT , Tay KK , Karen‐Ng LP , Cheong SC , Zain RB
Published: December 2013

Objectives

The objective of the study was to determine the prevalence of HPV seropositivity among patients with oral squamous cell carcinoma (OSCC) and healthy individuals and to correlate the association between HPV 16 seropositivity and risk of OSCC.

Materials and Methods

HPV 16 E6 and E7 plasmids were constructed for the production of recombinant protein, which was used as the antigen in ELISA. HPV ELISA was performed on serum samples from 50 healthy individuals and 50 patients with OSCC.

Results

Using the HPV ELISA, 30% (OR = 2.25, 95% CI = 0.85–5.93) and 18% (OR = 1.61, 95% CI = 0.53–4.92) of patients with oral cancer were found to be HPV 16 E6 and E7 seropositive, respectively. Significant association was found between HPV 16 seropositivity and increased risk of OSCC in men, but not in male subjects. A similar trend was observed in non‐betel quid chewers.

Conclusions

Potential associations between HPV 16 E6/E7 seropositivity and oral cancer were revealed in men and non‐betel quid chewer subjects, suggesting a possible etiological role of HPV 16 in subgroup of patients with OSCC in Malaysia.
China's Competing and Co‐opting Nationalisms: Implications to Sino–Japanese Relations
Authors: Tan Alexander C. , Chen Boyu
Published: December 2013

This paper contends that nationalism has always been a constant feature of Chinese politics. Indeed in order to understand the implications of China's nationalism vis‐à‐vis its emergence of China in global and regional politics, one has to examine the delicate equilibrium between state nationalism and ethnic nationalism. We put forward two hypotheses: first, if ethnic nationalism is more likely to be mobilized vis‐à‐vis state nationalism then an aggressive and assertive nationalism may emerge which is likely to lead to more confrontational foreign relations; second, when ethnic nationalist interests are suppressed, a more affirmative (or pragmatic) brand of nationalism tends to prevail. We argue that it is in the balancing act conducted by Chinese political elites that we can understand how nationalism has affected domestic politics. We then translate this understanding to regional politics, in particular China's relations with Japan and Taiwan.
EastAsianFinancial Regionalism and the Politics of Global Financial Governance: Structural and Institutional Power in Global and Regional Governance
Authors: Choi Ji Young
Published: December 2013

TheAsianFinancialCrisis in 1997–1998 and the mishandling of the crisis by the International Monetary Fund (IMF) and theUnited Statescatalyzed the rise ofEastAsian financial regionalism. In spite of skepticism, region‐wide financial arrangements inEastAsia have continually evolved and a new multilateral financial lending facility in the region was finally launched. However, the financial lending facility inEastAsia is still linked to theIMF, a global institution, and has significant limits in its capacity. In the wake of theGlobalFinancialCrisis, mounting criticism resurfaced against theIMF's legitimacy and effectiveness, but its reform process has been sluggish and its outcome remains uncertain. My argument here is that the limits ofEastAsian financial regionalism and the slow and uncertain reform process of theIMF, which is the linchpin of global financial governance, are attributed to the path‐dependent nature of the structural and institutional power of the United States. This study aims to show that power is an integral element of global and regional governance, and global structures and institutions, originally created by a hegemonic state, can have long‐lasting effects even though the hegemon is in decline.
The Optimal Path of aChina–Japan–KoreaFTA: Multilateral Path or Sequential Path?
Authors: Choi Youngmi
Published: December 2013

This study aims to analyze the possibility of a multilateralNortheastAsian free‐trade agreement (FTA), aChina–Japan–KoreaFTA(CJK FTA), and estimates the optimal path towards achieving it. Although there have been a number of studies examining why aCJK FTAshould be formed given its likely welfare‐enhancing effects, studies on precisely how and through what paths it might be formed are extremely scarce. Investigating the influences from industry interest groups and national security relations amongChina,Japan andSouthKorea, this study finds that a multilateral path (rather than a sequential path) whereinSouthKorea plays a key role as a hub (rather than a leader) is the optimal route for establishing aCJK FTA. Although two possible bilateralFTAs (aChina–KoreaFTAand aJapan–KoreaFTA) are more likely to be feasible, in particular, they are less likely to serve as a stepping‐stone to multilateralFTAformation. Consequently, this study mainly argues thatChina,Japan, andSouthKorea, the three main economies inNortheastAsia, should simultaneously participate in a single round of trade negotiations in order to establish aCJK FTA.
Increased Levels of Cytokines in Cerebrospinal Fluid of Children with Aseptic Meningitis Caused by Mumps Virus and Echovirus 30
Authors: Sulik A. , Kroten A. , Wojtkowska M. , Oldak E.
Published: December 2013

We measured levels of pro‐inflammatory cytokines in the cerebrospinal fluid (CSF) of patients with mumps meningitis, enteroviral echovirus 30 meningitis and children without central nervous system infection to investigate whether these molecules were involved in the pathogenesis of viral meningitis. The CSF was obtained from 62 children suspected with meningitis. These patients were classified to the mumps meningitis (n = 19), echovirus 30 meningitis (n = 22) and non‐meningitis (n = 21) groups. The concentrations of interleukin‐1 (IL‐1), interleukin‐1 soluble receptor type 2 (IL‐1R2), interleukin‐8 (IL‐8), human interferon gamma (IFN‐γ) and human tumour necrosis factor alpha (TNF‐α) were determined by immunoassay. A significant increase was noted in the levels of IL‐8, TNF‐α and IL‐1R2 in the CSF of both meningitis groups as compared to controls. The concentrations of IFN‐γ and IL‐1 differed significantly only between the mumps group and control. The levels of IL‐1, IFN‐γ and TNF‐α were significantly higher in mumps meningitis when compared to the echovirus 30 group. Of all cytokines examined, only IFN‐γ correlated with pleocytosis (r = 0.58) in the mumps meningitis group. The increased CSF cytokine levels are markers of meningeal inflammation, and each virus may cause a specific profile of the cytokine pattern.
Peripheral and Site‐Specific CD4+CD28null T Cells from Rheumatoid Arthritis Patients Show Distinct Characteristics
Authors: Pieper J. , Johansson S. , Snir O. , Linton L. , Rieck M. , Buckner J. H. , Winqvist ‎O. , van Vollenhoven R. , Malmström V.
Published: December 2013

Proinflammatory CD4+CD28null T cells are frequently found in the circulation of patients with rheumatoid arthritis (RA), but are less common in the rheumatic joint. In the present study, we sought to identify functional differences between CD4+CD28null T cells from blood and synovial fluid in comparison with conventional CD28‐expressing CD4+ T cells. Forty‐four patients with RA, displaying a distinct CD4+CD28null T cell population in blood, were recruited for this study; the methylation status of the IFNG locus was examined in isolated T cell subsets, and intracellular cytokine production (IFN‐γ, TNF, IL‐17) and chemokine receptor expression (CXCR3, CCR6 and CCR7) were assessed by flow cytometry on T cells from the two compartments. Circulating CD4+CD28null T cells were significantly more hypomethylated in the CNS‐1 region of the IFNG locus than conventional CD4+CD28+ T cells and produced higher levels of both IFN‐γ and TNF after TCR cross‐linking. CD4+CD28null T cells from the site of inflammation expressed significantly more CXCR3 and CCR6 compared to their counterparts in blood. While IL‐17A production could hardly be detected in CD4+CD28null cells from the blood, a significant production was observed in CD4+CD28null T cells from synovial fluid. CD4+CD28null T cells were not only found to differ from conventional CD4+CD28+ T cells in the circulation, but we could also demonstrate that synovial CD4+CD28null T cells showed additional effector functions (IL‐17 coproduction) as compared to the same subset in peripheral blood, suggesting an active role for these cells in the perpetuation of inflammation in the subset of patients having a CD28null population.
Passive Transfer of Tumour‐Derived MDSCs Inhibits Asthma‐Related Airway Inflammation
Authors: Song C. , Yuan Y. , Wang X.‐M. , Li D. , Zhang G.‐M. , Huang B. , Feng Z.‐H.
Published: December 2013

Myeloid‐derived suppressor cells (MDSCs), a heterogeneous population including myeloid progenitor and immature myeloid cells, are known to inhibit T cell responses. The issue of whether tumour‐derived MDSCs regulate the immune response in an asthma environment is currently unclear. Here, we have reported that tumour‐derived MDSCs shift the balance back to normal in a Th2‐dominant asthmatic environment. In an ovalbumin (OVA)‐induced mouse asthma model, injected tumour‐derived MDSCs were recruited to the lungs of asthmatic mice by CC chemokine ligand 2 (CCL2). MDSCs transferred into asthmatic mice via i.v. injection suppressed the infiltration of inflammatory cells into the lung, the Th2 cytokine, IL‐4, concentration in bronchial lavage fluid and the serum level of OVA‐specific IgE. Increased TGF‐β1 production in the lung was detected after transfer of MDSCs. The inhibitory effects of MDSCs were reversed upon treatment with an anti‐TGF‐β1 antibody, suggesting dependence of these activities on TGF‐β1. Our findings imply that tumour‐derived MDSCs inhibit the Th2 cell‐mediated response against allergen in a TGF‐β1‐dependent manner. Based on the collective results, we propose that asthma may be effectively targeted using a novel MDSC‐based cell therapy approach.
Math Autobiographies: A Window into Teachers' Identities as Mathematics Learners
Authors: McCulloch Allison W. , Marshall Patricia L. , DeCuir‐Gunby Jessica T. , Caldwell Ticola S.
Published: December 2013

Mathematics autobiographies have the potential to help teachers reflect on their identities as mathematics learners and to understand their role in the development of their students' mathematics identities. This paper reports on a professional development project for K‐2 teachers (n = 41), in which participants were asked to write mathematics autobiographies. Using an adaptation of an existing framework for characterizing teachers' mathematics stories, we describe the consistencies among the participants' experiences as mathematics learners and the events that are identified as being the impetus for a transition from a negative to a positive attitude toward mathematics. Implications for both teachers and teacher educators are presented.
Prospective Elementary Teachers' Perceptions of Gender Differences in Children's Attitudes Toward Mathematics
Authors: Schwartz Catherine S. , Sinicrope Rose
Published: December 2013

Prospective elementary teachers hold preconceived ideas about elementary school students' attitudes toward mathematics. We found that there exists a gender bias with prospective teachers expecting girls to have negative attitudes toward mathematics and boys more likely to have positive attitudes toward mathematics. We found that these expectations exist for both prospective teachers in a traditional undergraduate degree program and prospective teachers in an alternative licensure graduate degree program. We also found that these expectations do change with the completion of a mathematics methods course and classroom experiences.
Disease distribution in canine patients with acanthocytosis: 123 cases
Authors: Warry Emma , Bohn Andrea , Emanuelli Mauren , Thamm Douglas , Lana Susan
Published: December 2013

Background

An acanthocyte is an abnormally shaped erythrocyte. In veterinary medicine, acanthocytes have historically been associated with canine hemangiosarcoma. In human medicine, acanthocytes are rarely observed with neoplastic disease and are more commonly associated with a variety of hereditary and acquired diseases.

Objectives

The purpose of the study was to determine what disease processes are associated with the presence of acanthocytes in the peripheral blood of dogs.

Methods

Medical records for dogs presented to the Veterinary Teaching Hospital of Colorado State University during January 2004 through June 2008 with acanthocytes documented in their CBCs were retrospectively reviewed.

Results

A total of 123 dogs were included, 66 of which were diagnosed with neoplastic disease, most commonly hemangiosarcoma (n = 12), osteosarcoma (n = 11), and lymphoma (n = 11). The remaining 57 dogs had nonneoplastic disease, most commonly observed were gastrointestinal (n = 13), musculoskeletal (n = 8), renal (n = 8), and immune‐mediated diseases (n = 7). No statistically significant difference was detected between percent acanthocytes present in dogs with neoplastic and nonneoplastic diseases.

Conclusion

Acanthocytosis was observed with a variety of neoplastic and nonneoplastic diseases. While clearly commonly associated, the presence of acanthocytes in a blood smear should not be considered pathognomonic for hemangiosarcoma in dogs.
Knowledge of HIV testing and attitudes towards blood donation at three blood centres in Brazil
Authors: Miranda C. , Moreno E. , Bruhn R. , Larsen N. M. , Wright D. J. , Oliveira C. D. L. , Carneiro‐Proietti A. B. F. , Loureiro P. , de Almeida‐Neto C. , Custer B. , Sabino E. C. , Gonçalez T. T. ,   for the NHLBI Retrovirus Epidemiology Donor Study‐II (REDS‐II), International Component
Published: December 2013

Background

Reducing risk of HIV window period transmission requires understanding of donor knowledge and attitudes related to HIV and risk factors.

Study Design and Methods

We conducted a survey of 7635 presenting blood donors at three Brazilian blood centres from 15 October through 20 November 2009. Participants completed a questionnaire on HIV knowledge and attitudes about blood donation. Six questions about blood testing and HIV were evaluated using maximum likelihood chi‐square and logistic regression. Test seeking was classified in non‐overlapping categories according to answers to one direct and two indirect questions.

Results

Overall, respondents were male (64%) repeat donors (67%) between 18 and 49 years old (91%). Nearly 60% believed blood centres use better HIV tests than other places; however, 42% were unaware of the HIV window period. Approximately 50% believed it was appropriate to donate to be tested for HIV, but 67% said it was not acceptable to donate with risk factors even if blood is tested. Logistic regression found that less education, Hemope‐Recife blood centre, replacement, potential and self‐disclosed test‐seeking were associated with less HIV knowledge.

Conclusion

HIV knowledge related to blood safety remains low among Brazilian blood donors. A subset finds it appropriate to be tested at blood centres and may be unaware of the HIV window period. These donations may impose a significant risk to the safety of the blood supply. Decreasing test‐seeking and changing beliefs about the appropriateness of individuals with behavioural risk factors donating blood could reduce the risk of transfusing an infectious unit.
Modeling Geometric Nonlinearities in the Free Vibration of a Planar Beam Flexure With a Tip Mass
Authors: Moeenfard Hamid , Awtar Shorya
Published: December 2013

The objective of this work is to analytically study the nonlinear dynamics of beam flexures with a tip mass undergoing large deflections. Hamilton's principle is utilized to derive the equations governing the nonlinear vibrations of the cantilever beam and the associated boundary conditions. Then, using a single mode approximation, these nonlinear partial differential equations are reduced to two coupled nonlinear ordinary differential equations. These equations are solved analytically using the multiple time scales perturbation technique. Parametric analytical expressions are presented for the time domain response of the beam around and far from its internal resonance state. These analytical results are compared with numerical ones to validate the accuracy of the proposed analytical model. Compared with numerical solution methods, the proposed analytical technique shortens the computational time, offers design insights, and provides a broader framework for modeling more complex flexure mechanisms. The qualitative and quantitative knowledge resulting from this effort is expected to enable the analysis, optimization, and synthesis of flexure mechanisms for improved dynamic performance.
The Impact of Team-Based Product Dissection on Design Novelty
Authors: Toh Christine A. , Miller Scarlett R. , Okudan Kremer Gül E.
Published: December 2013

Although design novelty is a critical area of research in engineering design, most research in this space has focused on understanding and developing formal idea generation methods instead of focusing on the impact of current design practices. This is problematic because formal techniques are often not adopted in industry due to the burdensome steps often included in these methods, which limit the practicality and adoption of these methods. This study seeks to understand the impact of product dissection, a design method widely utilized in academia and industry, on design novelty in order to produce recommendations for the use or alterations of this method for supporting novelty in design. To investigate the impact of dissection, a study was conducted with 76 engineering students who completed a team-based dissection of an electric toothbrush and then individually generated ideas. The relationships between involvement in the dissection activity, the product dissected, the novelty and quantity of the ideas developed were investigated. The results reveal that team members who were more involved in the dissection activity generated concepts that were more novel than those who did not. In addition, the type of the dissected product also had an influence on design novelty. Finally, a positive correlation between the number of ideas generated and the novelty of the design concepts was identified. The results from this study are used to provide recommendations for leveraging product dissection for enhancing novelty in engineering design education and practice.
A Simple Procedure for the Solution of Three-Dimensional Wheel/Rail Conformal Contact Problem
Authors: Recuero Antonio M. , Shabana Ahmed A.
Published: December 2013

This paper describes a simple and efficient procedure for the treatment of conformal contact conditions with special emphasis on railroad wheel/rail contacts. The general three-dimensional nonconformal contact conditions are briefly reviewed. These nonconformal contact conditions, which are widely used in many applications because of their generality, allow for predicting online one point of contact, provided that the two surfaces in contact satisfy certain geometric requirements. These nonconformal contact conditions fail when the solution is not unique as the result of using conformal surface profiles or surface flatness, situations often encountered in many applications including railroad wheel/rail contacts. In these cases, the Jacobian matrix obtained from the differentiation of the nonconformal contact conditions with respect to the surface parameters suffer from singularity that causes interruption of the computer simulations. The singularities and the fundamental issues that arise in the case of conformal contact are discussed, and a simple and computationally efficient procedure for avoiding such singularities in general multibody systems (MBS) algorithms is proposed. In order to demonstrate the use of the proposed procedure, the wheel climb of a wheelset as the result of an external lateral force is considered as an example. In this example, the wheel and rail profiles lead to conformal contact scenarios that could not be simulated using the nonconformal contact conditions.
Effect of Cooling Rate on Mechanical Properties of 7075 Aluminum Rods Extruded in Semisolid State
Authors: Ketabchi Mostafa , Amin Shafaat Mohammad , Shafaat Iman , Abbasi Mahmoud
Published: December 2013

Semisolid extrusion of metals involves extrusion of metallic alloys with a microstructure consisting of spherical solids in a liquid matrix. In this research, the effect of cooling rate during forward semisolid extrusion on microstructure and mechanical properties of 7075 aluminum was investigated. Semisolid microstructure was prepared according to the recrystallization and partial melting (RAP) method. Optimum semisolid temperature and holding time which were resulted in a suitable microstructure for specimens were determined at 580 °C for 10 min. Different cooling rates were applied during semisolid extrusion and the resulted mechanical properties were studied. Tensile properties of semisolid extruded rods in T6 condition were also compared with those of conventionally extruded specimen. The results indicate that utilizing optimum values of semisolid extrusion parameters, namely, temperature and time of heating as well as cooling rate severity, brings both the possibility to obtain mechanical properties of conventionally extruded specimens and to get advantages of semisolid forming technique. Experimental results also show that increment of cooling rate and extrusion pressure improves the mechanical properties.
Experimental and Numerical Determination of Interface Slip Coefficient of Fluid Stream Exiting a Partially Filled Porous Medium Channel
Authors: Narasimhan Arunn , Raju K. S. , Chakravarthy S. R.
Published: December 2013

Stacks of parallel plates modeled as a standard fissure-type anisotropic porous medium are filled inside a rectangular channel up to half the cross section height. The interface slip coefficient α for the isothermal laminar incompressible flow exiting this partially filled porous-medium channel is then determined using particle image velocimetry (PIV) experiments and numerical simulations. Required measurements of the Darcy velocity uD on the porous-medium (PM) side, the local velocity uf, and its gradient ∂uf/∂y on the clear-fluid (CF) side are performed across different length scales. The fissure-type porous-medium parameters are systematically varied in the porosity range 0.2≤φ≤0.95 and flow direction permeability 10-6<K,m2<10-9. From the exit-velocity profile, the empirical slip coefficient α is determined using a generalized relationship. When the measurements across the PM-CF interface are performed across a length scale equal to the representative elemental length (REL) of the porous media considered (i.e., equal to the sum of plate thickness (a) and gap (b)), the determined α value is found to remain invariant.
An Improved Direct-Forcing Immersed Boundary Method for Fluid-Structure Interaction Simulations1
Authors: Zhu Xiaojue , He Guowei , Zhang Xing
Published: December 2013

In the present work, we present an improved version of the direct-forcing immersed boundary (IB) method proposed in Wang and Zhang (2011, “An Immersed Boundary Method Based on Discrete Stream Function Formulation for Two- and Three-Dimensional Incompressible Flows,” J. Comput. Phys., 230(9), pp. 3479–3499). In order to obtain an accurate prediction of local surface force, measures have been taken to suppress the unphysical spatial oscillations in the Lagrangian forcing. A fluid-structure interaction (FSI) solver has been developed by using the improved IB method for the fluid and the finite difference method for the structure. Several flow problems are simulated to validate our method. The testing cases include flows over a stationary cylinder and a stationary flat plate, two-dimensional flow past an inextensible flexible filament, and three-dimensional flow past a flapping flag. The results obtained in the present work agree well with those from the literature.
A Sharp Interface Direct Forcing Immersed Boundary Approach for Fully Resolved Simulations of Particulate Flows
Authors: Yang Jianming , Stern Frederick
Published: December 2013

In recent years, the immersed boundary method has been well received as an effective approach for the fully resolved simulations of particulate flows. Most immersed boundary approaches for numerical studies of particulate flows in the literature were based on various discrete delta functions for information transfer between the Lagrangian elements of an immersed object and the underlying Eulerian grid. These approaches have some inherent limitations that restrict their wider applications. In this paper, a sharp interface direct forcing immersed boundary approach based on the method proposed by Yang and Stern (Yang and Stern, 2012, “A Simple and Efficient Direct Forcing Immersed Boundary Framework for Fluid-Structure Interactions,” J. Comput. Phys., 231(15), pp. 5029–5061) is given for the fully resolved simulations of particulate flows. This method uses a discrete forcing approach and maintains a sharp profile of the fluid-solid interface. It is not limited to low Reynolds number flows and the immersed boundary discretization can be arbitrary or totally eliminated for particles with analytical shapes. In addition, it is not required to calculate the solid volume fraction in low density ratio problems. A strong coupling scheme is employed for the fluid-solid interaction without including the fluid solver in the predictor-corrector iterative loop. The overall algorithm is highly efficient and very attractive for simulating particulate flows with a wide range of density ratios on relatively coarse grids. Several cases are examined and the results are compared with reference data to demonstrate the simplicity and robustness of our method in particulate flow simulations. These cases include settling and buoyant particles and the interaction of two settling particles showing the kissing-drafting-tumbling phenomenon. Systematic verification studies show that our method is of second-order accuracy on very coarse grids and approaches fourth-order accuracy on finer grids.
Renewable Hydrogen Production Using Sailing Ships
Authors: Platzer Max F. , Sarigul-Klijn Nesrin , Young J. , Ashraf M. A. , Lai J. C. S.
Published: December 2013

Vast ocean areas of planet Earth are exposed year-round to strong wind currents. We suggest that this untapped ocean wind power be exploited by the use of sailing ships. The availability of constantly updated meteorological information makes it possible to operate the ships in ocean areas with optimum wind power so that the propulsive ship power can be converted into electric power by means of ship-mounted hydro-power generators. Their electric power output then is fed into ship-mounted electrolyzers to convert sea water into hydrogen and oxygen. In this paper, we estimate the ship size, sail area, and generator size to produce a 1.5 MW electrical power output. We describe a new oscillating-wing hydro-power generator and present results of model tests obtained in a towing tank. Navier-Stokes computations are presented to provide an estimate of the power extraction efficiency and drag coefficient of such a generator which depends on a range of parameters such as foil maximum pitch angles, plunge amplitude, phase between pitch and plunge and load. Also, we present a discussion of the feasibility of sea water electrolysis and of the reconversion of hydrogen and oxygen into electricity by means of shore-based hydrogen-oxygen power plants.
Characterization of the Mechanical Properties of Monolayer Molybdenum Disulfide Nanosheets Using First Principles
Authors: Ansari R. , Malakpour S. , Faghihnasiri M. , Ajori S.
Published: December 2013

Recently, synthesized inorganic two-dimensional monolayer nanostructures are very promising to be applied in electronic devices. This article explores the mechanical properties of a monolayer molybdenum disulfide (MoS2) including Young's bulk and shear moduli and Poisson's ratio by applying density functional theory (DFT) calculation based on the generalized gradient approximation (GGA). The results demonstrate that the elastic properties of MoS2 nanosheets are less than those of graphene and hexagonal boron-nitride (h-BN) nanosheets. However, their Poisson's ratio is found to be higher than that of graphene and h-BN nanosheet. It is also observed that due to the special structure of MoS2, the thickness of nanosheet changes when the axial strain is applied.
Bottlenose dolphin (Tursiops truncatus) detection of simulated echoes from normal and time-reversed clicks
Authors: Finneran James J. , Wu Teri , Borror Nancy , Tormey Megan , Brewer Arial , Black Amy , Bakhtiari Kimberly
Published: December 2013

In matched filter processing, a stored template of the emitted sonar pulse is compared to echoes to locate individual replicas of the emitted pulse embedded in the echo stream. A number of experiments with bats have suggested that bats utilize matched filter processing for target ranging, but not for target detection. For dolphins, the few available data suggest that dolphins do not utilize matched filter processing. In this study, the effect of time-reversing a dolphin's emitted click was investigated. If the dolphin relied upon matched filter processing, time-reversal of the click would be expected to reduce the correlation between the (unaltered) click and the echoes and therefore lower detection performance. Two bottlenose dolphins were trained to perform a phantom echo detection task. On a small percentage of trials (“probe trials”), a dolphin's emitted click was time-reversed before interacting with the phantom echo system. Data from the normal and time-reversed trials were then analyzed and compared. There were no significant differences in detection performance or click emissions between the normal and time-reversed conditions for either subject, suggesting that the dolphins did not utilize matched filter processing for this echo detection task.
Integrating cognitive and peripheral factors in predicting hearing-aid processing effectiveness
Authors: Kates James M. , Arehart Kathryn H. , Souza Pamela E.
Published: December 2013

Individual factors beyond the audiogram, such as age and cognitive abilities, can influence speech intelligibility and speech quality judgments. This paper develops a neural network framework for combining multiple subject factors into a single model that predicts speech intelligibility and quality for a nonlinear hearing-aid processing strategy. The nonlinear processing approach used in the paper is frequency compression, which is intended to improve the audibility of high-frequency speech sounds by shifting them to lower frequency regions where listeners with high-frequency loss have better hearing thresholds. An ensemble averaging approach is used for the neural network to avoid the problems associated with overfitting. Models are developed for two subject groups, one having nearly normal hearing and the other mild-to-moderate sloping losses.
The equivalent incidence angle for porous absorbers backed by a hard surface
Authors: Jeong Cheol-Ho , Brunskog Jonas
Published: December 2013

An equivalent incidence angle is defined as the incidence angle at which the oblique incidence absorption coefficient best approximates the random incidence absorption coefficient. Once the equivalent angle is known, the random incidence absorption coefficient can be estimated by a single experiment using a free-field absorption measurement technique with a source at the equivalent angle. This study investigates the equivalent angle for locally and extendedly reacting porous media mainly by a numerical approach: Numerical minimizations of a cost function that is the difference between the oblique incidence absorption coefficient at a specific incidence angle and the random incidence absorption coefficient. The equivalent angle is found to be around 55° under local reaction conditions, and 45° for extendedly reacting porous absorbers. As practical guidelines for measuring absorption coefficients by free-field techniques, a broad incidence angle range can be suggested: 20° ≤ θi ≤ 65° for extended reaction and θi ≤ 65° for locally reacting porous absorbers, if an average difference of 0.05 is allowed.
Sound absorption of porous substrates covered by foliage: Experimental results and numerical predictions
Authors: Ding Lei , Van Renterghem Timothy , Botteldooren Dick , Horoshenkov Kirill , Khan Amir
Published: December 2013

The influence of loose plant leaves on the acoustic absorption of a porous substrate is experimentally and numerically studied. Such systems are typical in vegetative walls, where the substrate has strong acoustical absorbing properties. Both experiments in an impedance tube and theoretical predictions show that when a leaf is placed in front of such a porous substrate, its absorption characteristics markedly change (for normal incident sound). Typically, there is an unaffected change in the low frequency absorption coefficient (below 250 Hz), an increase in the middle frequency absorption coefficient (500–2000 Hz) and a decrease in the absorption at higher frequencies. The influence of leaves becomes most pronounced when the substrate has a low mass density. A combination of the Biot's elastic frame porous model, viscous damping in the leaf boundary layers and plate vibration theory is implemented via a finite-difference time-domain model, which is able to predict accurately the absorption spectrum of a leaf above a porous substrate system. The change in the absorption spectrum caused by the leaf vibration can be modeled reasonably well assuming the leaf and porous substrate properties are uniform.
Absorption of sound by porous layers with embedded periodic arrays of resonant inclusions
Authors: Lagarrigue C. , Groby J. P. , Tournat V. , Dazel O. , Umnova O.
Published: December 2013

The aim of this work is to design a layer of porous material with a high value of the absorption coefficient in a wide range of frequencies. It is shown that low frequency performance can be significantly improved by embedding periodically arranged resonant inclusions (slotted cylinders) into the porous matrix. The dissipation of the acoustic energy in a porous material due to viscous and thermal losses inside the pores is enhanced by the low frequency resonances of the inclusions and energy trapping between the inclusion and the rigid backing. A parametric study is performed in order to determine the influence of the geometry and the arrangement of the inclusions embedded in a porous layer on the absorption coefficient. The experiments confirm that low frequency absorption coefficient of a composite material is significantly higher than that of the porous layer without the inclusions.
Surface waves over periodically-spaced rectangular strips
Authors: Bashir Imran , Taherzadeh Shahram , Attenborough Keith
Published: December 2013

Frequency- and time-domain measurements have been made on surfaces composed from parallel periodically-spaced rectangular strips (width: 0.0126 m, height: 0.0253 m) on an acoustically hard surface. The edge-to-edge spacing between the strips has been varied between 0.003 and 0.06 m. Frequency domain predictions show that when the spacing is small, these surfaces may be regarded as locally reacting rigid-framed hard-backed slit-pore layers with an effective depth slightly larger than the strip height, but when the spacing is comparable to the strip height or greater, the surfaces behave as periodically rough surfaces. Both frequency- and time-domain results show that surface waves of comparable magnitudes are created over the range of strip spacings studied but the frequency content of the acoustically induced surface waves decreases as the mean spacing is increased. It is found that surface wave dispersion is better predicted by the deduced effective impedance spectrum than by the slit-pore layer impedance model.
The effect of particle shape and size distribution on the acoustical properties of mixtures of hemp particles
Authors: Glé Philippe , Gourdon Emmanuel , Arnaud Laurent , Horoshenkov Kirill-V. , Khan Amir
Published: December 2013

Hemp concrete is an attractive alternative to traditional materials used in building construction. It has a very low environmental impact, and it is characterized by high thermal insulation. Hemp aggregate particles are parallelepiped in shape and can be organized in a plurality of ways to create a considerable proportion of open pores with a complex connectivity pattern, the acoustical properties of which have never been examined systematically. Therefore this paper is focused on the fundamental understanding of the relations between the particle shape and size distribution, pore size distribution, and the acoustical properties of the resultant porous material mixture. The sound absorption and the transmission loss of various hemp aggregates is characterized using laboratory experiments and three theoretical models. These models are used to relate the particle size distribution to the pore size distribution. It is shown that the shape of particles and particle size control the pore size distribution and tortuosity in shiv. These properties in turn relate directly to the observed acoustical behavior.