bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Impedance Method for Dynamic Analysis of Active Material Systems
Authors: Liang C. , Sun F. P. , Rogers C. A. 
Published: August 2009

This paper describes a new approach to analyzing the dynamic response of active material systems with integrated induced strain actuators, including piezoelectric, electrostrictive, and magnetostrictive actuators. This approach, referred to as the impedance method, has many advantages compared with the conventional static approach and the dynamic finite element approach, such as pin force models and consistent beam and plate models. The impedance approach is presented and described using a simple example, a PZT actuator-driven one-degree-of-freedom spring-massdamper system, to demonstrate its ability to capture the physics of adaptive material systems, which is the impedance match between various active components and host-structures, and its utility and importance by means of an experimental example and a numerical case study. The conventional static and dynamic finite element approaches are briefly summarized. The impedance methodology is then discussed in comparison with the static approach. The basic elements of the impedance method, i.e., the structural impedance corresponding to actuator loading and the dynamic output characteristics of PZT actuators, are addressed. The advantages of using the impedance approach over conventional approaches are discussed using a simple numerical example. A comparison of the impedance method with the static and the dynamic finite element approaches are provided at the conclusion of this paper.
Application of Forced Electrification for Preparation of Complex Particles
Authors: Dan Takehiro , Egashira Mitsuru , Kyono Junro , Fudouzi Hiroshi , Shinya Norio 
Published: August 2009

The purposes of the present work are to describe the importance of the application of forced electrification on complex particle preparation and to develop new materials with multiple functions by combining two kinds of particles electrified reciprocally. This paper reports a preparation method and the positive temperature coefficient of resistivity (PTCR) characteristics of composites consisting of semiconductive BaTiO3 particles and metallic indium powder. The forced electrification technique was applied to a complex particle preparation process and confirmed to be effective as follows: 1. A vibrating cylindrical electrode can force-electrify metal, semiconductor and insulator particles with positive or negative charges. 2. When two kinds of particles electrified reciprocally are mixed in the same region at the same time, complex particles can be produced by the electrostatically attractive force working between them. 3. Indium-semiconductive BaTiO3 complex particles made with this processing offer a new PTCR material which can be used in arbitrary shapes by simple packing. This behavior cannot be accomplished by the conventionally sintered PTCR materials.
Power and Energy Characteristics of Solid-State Induced-Strain Actuators for Static and Dynamic Applications
Authors: Giurgiutiu Victor , Rogers Craig A. 
Published: August 2009

The power and energy characteristics of solid-state induced-strain actuators are studied. Piezoelectric (PZT), electrostrictive (PMN) and magnetostrictive (TERFENOL) actuators are considered. The principles and internal construction of solid-state induced-strain actuators are briefly reviewed. Typical performance curves are presented and discussed. The basic equations of piezoelectricity and piezomagnetism are presented. A linearization procedure is adopted whereby apparent values for the piezoelectric and piezomagnetic constants are derived from full-stroke ven-dor data using the secant approximation principle. Values for the apparent electromagnetic conversion coefficient for full-stroke operation are obtained. The static analysis considers the one-directional operation of the induced strain actuators against an external spring load. It is found that the maximum energy output from the induced-strain actuator is obtained when the internal and external stiffnesses are matched. Expressions for the maximum energy output, and the energy densities per unit volume, mass, and cost are derived. Numerical examples and comparative charts are given for a number of piezoelectric, electrostrictive and magnetostrictive actuators. The influence of casing and pre-stress mechanism on the overall energy density values is also highlighted. The electromechanical conversion efficiency is studied, and two separate expressions are derived, one for the best efficiency, and another for the conversion efficiency at the stiffness match point. The dynamic analysis considers the cyclic motion of the induced-strain actuators about a midpoint bias position. The dynamic full-stroke is found approximately one-half the static full-stroke. The correspondingly maximum output energy and energy densities under dynamic conditions are calculated. The dynamic energy conversion efficiency is studied and the influence of bias voltage or current is included. Numerical examples and comparative charts are given for a number of piezoelectric, electrostrictive and magnetostrictive actuators operating under dynamic conditions.
Thickness Vibrations of Sandwich Plates and Beams and Delamination Detection
Authors: Jensen Alf Egil , Irgens Fridtjov 
Published: August 2009

In multi-hull marine vehicles assembled by FRP sandwich composite materials, problems with delamination and skin/core debonding are reported. An early damage warning (EDW) system for delamination detection in marine vessels based on measurements of bending vibrations in sandwich structures are under development. Related to this EDW system development, this paper presents a theory for qualitative determination of thickness vibrations in sandwich plates and beams. The core is modelled as a two-parameter foundation where shearing interaction effects and normal stress effects in the core are included. The skins are modelled as ordinary plates or beams on a foundation. Expressions for both thickness shear and thickness stretch modes are given. In addition to the theoretical development, experiments with a simply supported sandwich beam, using a TV-holography technique, were performed and good agreement between theory and experiments was achieved. With the expressions for thickness shear and thickness stretch frequencies presented in this paper one is able to qualitatively determine thickness vibration frequencies. It is particularly important to determine whether thickness vibrations are present in the same frequency range as the bending frequencies of interest in the EDW system. The occurrence of a thickness shear frequency and an occasional non-existence of a higher bending frequency may be misinterpreted as a down shift of the bending frequency and thus lead to an incorrect delamination detection.
Polyurethane Actuators Using Bending Piezoelectricity and Bending Electrostriction
Authors: Watanabe Masashi , Hirai Toshihiro , Ueda Tsutomu , Suzuki Makoto , Amaike Yoichi 
Published: August 2009

A large bending deformation of monolayer polyurethane films was observed when a high electric field was applied to the film. Using this phenomenon, bending actuators were prepared and their electromechanical properties were investigated. When the electric field of 10 MV/m was applied to the film, the deformation curvature, IhR, reached 36 m-l within about 3 seconds and the generated force was about the same as the film weight. The degree of the bending deformation was expressed as a combination of the linear term and the square term of the applied electric field. Therefore, it was shown that the bending deformation is caused by bending piezoelectricity (inverse effect) and bending electrostriction.
Detection of the Failure Zone Caused by Cyclic Loading
Authors: Ichinose Kensuke , Kosaka Yoshimi , Fukuda Katsumi , Taniuchi Kiyoshi 
Published: August 2009

There is a simplified technique for detecting where the part of a structure undergoes failure due to cyclic loading; this technique appears to be of great practical value in its employment to prevent fracture. It is well known that when yield stress is applied to a low-carbon steel plate, Luders' lines become visible on its surface to the naked eye. It is a plausible hypothesis that the locations on the surface of the plate where the Luders' lines appear are in a state of failure. The correlation of cyclic loading and Luders' lines should confirm whether or not Luders' lines reliably indicate where failure results from fatigue loading. The Ra value of the surface roughness of the specimen before and after the appearance of Luders' lines is used to ascertain this correlation. The present paper takes up cyclic tensile loading with shoulder fillets as a concrete example of the correlation of failure and stress.
Unloader Braces for Medial Compartment Knee Osteoarthritis: Implications on Mediating Progression
Authors: Ramsey Dan K. , Russell Mary E. 
Published: August 2009

Background: For persons with unicompartment knee osteoarthritis (OA), off-unloader braces are a mechanical intervention designed to reduce pain, improve physical function, and possibly slow disease progression. Pain relief is thought to be mediated by distracting the involved compartment via external varus or valgus forces applied to the knee. In so doing, tibiofemoral alignment is improved, and load is shifted off the degenerative compartment, where exposure to potentially damaging and provocative mechanical stresses are reduced. Objectives: To provide a synopsis of the evidence documented in the scientific literature concerning the efficacy of offloader knee braces for improving symptomatology associated with painful disabling medial compartment knee OA. Search Strategy: Relevant peer-reviewed publications were retrieved from a MEDLINE search using the terms with the reference terms osteoarthritis, knee, and braces (per Medical Subject Headings), plus a manual search of bibliographies from original and review articles and appropriate Internet resources. Results: For persons with combined unicompartment knee OA and mild to moderate instability, the strength of recommendation reported by the Osteoarthritis Research Society International in the ability of off-loader knee braces to reduce pain, improve stability, and diminish the risk of falling was 76% (95% confidence interval, 69%–83%). The more evidence the treatment is effective, the higher the percentage. Conclusions: Given the encouraging evidence that off-loader braces are effective in mediating pain relief in conjunction with knee OA and malalignment, bracing should be fully used before joint realignment or replacement surgery is considered. With the number of patients with varus deformities and knee pain predicted to increase as the population ages, a reduction of patient morbidity for this widespread chronic condition in combination with this treatment modality could have a positive impact on health care costs and the economic productivity and quality of life of the affected individuals.
Thrombin induces the expression of oncostatin M via AP-1 activation in human macrophages: a link between coagulation and inflammation
Authors: Kastl Stefan P. , Speidl Walter S. , Katsaros Katharina M. , Kaun Christoph , Rega Gersina , Assadian Afshin , Hagmueller Georg W. , Hoeth Martina , de Martin Rainer , Ma Yongsheng , Maurer Gerald , Huber Kurt , Wojta Johann 
Published: August 2009

AbstractMacrophages as inflammatory cells are involved in the pathogenesis of atherosclerosis that today is recognized as an inflammatory disease. Activation of coagulation leads to the late complication of atherosclerosis, namely atherothrombosis with its clinical manifestations stroke, unstable angina, myocardial infarction, and sudden cardiac death. Thus inflammation and coagulation play fundamental roles in the pathogenesis of atherosclerosis. We show that the coagulation enzyme thrombin up-regulates oncostatin M (OSM), a pleiotropic cytokine implicated in the pathophysiology of vascular disease, in human monocyte-derived macrophages (MDMs) up to 16.8-fold. A similar effect was seen in human peripheral blood monocytes and human plaque macrophages. In MDMs, the effect of thrombin on OSM was abolished by PPACK and mimicked by a PAR-1–specific peptide. Thrombin induced phosphorylation of ERK1/2 and p38 in MDMs. The ERK1/2 inhibitor PD98059 blocked the effect of thrombin on OSM production in MDMs, whereas the p38 inhibitor SB202190 had no effect. Thrombin induced translocation of c-fos and c-jun to the nucleus of MDMs. Using OSM promoter–luciferase reporter constructs transfected into MDMs, we show that a functional AP-1 site is required for promoter activation by thrombin. We present another link between coagulation and inflammation, which could impact on the pathogenesis of atherosclerosis.
Toward clinical therapies using hematopoietic cells derived from human pluripotent stem cells
Authors: Kaufman Dan S. 
Published: August 2009

AbstractHuman embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) provide remarkable cellular platforms to better understand human hematopoiesis and to develop clinically applicable hematopoietic cell–based therapies. Over the past decade, hESCs have been used to characterize molecular and cellular mechanisms underpinning the differentiation of hematopoietic progenitors and mature, functional hematopoietic cells. These advances are now poised to lead to clinical translation of hESC- and iPSC-derived hematopoietic cells for novel therapies in the next few years. On the basis of areas of recent success, initial clinical use of hematopoietic cells derived from human pluripotent stem cells will probably be in the areas of transfusion therapies (erythrocytes and platelets) and immune therapies (natural killer cells). In contrast, efficient development and isolation of hematopoietic stem cells capable of long-term, multilineage engraftment still remains a significant challenge. Technical, safety, and regulatory concerns related to clinical applications of human PSCs must be appropriately addressed. However, proper consideration of these issues should facilitate and not inhibit clinical translation of new therapies. This review outlines the current status of hematopoietic cell development and what obstacles must be surmounted to bring hematopoietic cell therapies from human PSCs from “bench to bedside.”
Which missing value imputation method to use in expression profiles: a comparative study and two selection schemes
Authors: Brock Guy N , Shaffer John R , Blakesley Richard E , Lotz Meredith J , Tseng George C 
Published: August 2009

Abstract

Background
Gene expression data frequently contain missing values, however, most down-stream analyses for microarray experiments require complete data. In the literature many methods have been proposed to estimate missing values via information of the correlation patterns within the gene expression matrix. Each method has its own advantages, but the specific conditions for which each method is preferred remains largely unclear. In this report we describe an extensive evaluation of eight current imputation methods on multiple types of microarray experiments, including time series, multiple exposures, and multiple exposures × time series data. We then introduce two complementary selection schemes for determining the most appropriate imputation method for any given data set.

Results
We found that the optimal imputation algorithms (LSA, LLS, and BPCA) are all highly competitive with each other, and that no method is uniformly superior in all the data sets we examined. The success of each method can also depend on the underlying "complexity" of the expression data, where we take complexity to indicate the difficulty in mapping the gene expression matrix to a lower-dimensional subspace. We developed an entropy measure to quantify the complexity of expression matrixes and found that, by incorporating this information, the entropy-based selection (EBS) scheme is useful for selecting an appropriate imputation algorithm. We further propose a simulation-based self-training selection (STS) scheme. This technique has been used previously for microarray data imputation, but for different purposes. The scheme selects the optimal or near-optimal method with high accuracy but at an increased computational cost.

Conclusion
Our findings provide insight into the problem of which imputation method is optimal for a given data set. Three top-performing methods (LSA, LLS and BPCA) are competitive with each other. Global-based imputation methods (PLS, SVD, BPCA) performed better on mcroarray data with lower complexity, while neighbour-based methods (KNN, OLS, LSA, LLS) performed better in data with higher complexity. We also found that the EBS and STS schemes serve as complementary and effective tools for selecting the optimal imputation algorithm.
Inferring gene expression dynamics via functional regression analysis
Authors: Müller Hans-Georg , Chiou Jeng-Min , Leng Xiaoyan 
Published: August 2009

AbstractBackgroundTemporal gene expression profiles characterize the time-dynamics of expression of specific genes and are increasingly collected in current gene expression experiments. In the analysis of experiments where gene expression is obtained over the life cycle, it is of interest to relate temporal patterns of gene expression associated with different developmental stages to each other to study patterns of long-term developmental gene regulation. We use tools from functional data analysis to study dynamic changes by relating temporal gene expression profiles of different developmental stages to each other.ResultsWe demonstrate that functional regression methodology can pinpoint relationships that exist between temporary gene expression profiles for different life cycle phases and incorporates dimension reduction as needed for these high-dimensional data. By applying these tools, gene expression profiles for pupa and adult phases are found to be strongly related to the profiles of the same genes obtained during the embryo phase. Moreover, one can distinguish between gene groups that exhibit relationships with positive and others with negative associations between later life and embryonal expression profiles. Specifically, we find a positive relationship in expression for muscle development related genes, and a negative relationship for strictly maternal genes forDrosophila, using temporal gene expression profiles.ConclusionOur findings point to specific reactivation patterns of gene expression during theDrosophilalife cycle which differ in characteristic ways between various gene groups. Functional regression emerges as a useful tool for relating gene expression patterns from different developmental stages, and avoids the problems with large numbers of parameters and multiple testing that affect alternative approaches.
Exposure to light enhances pre-adult fitness in two dark-dwelling sympatric species of ants
Authors: Lone Shahnaz Rahman , Sharma Vijay Kumar 
Published: August 2009

Abstract
Background
In insects, circadian clocks play a key role in enhancing fitness by regulating life history traits such as developmental time and adult lifespan. These clocks use environmental light/dark (LD) cycles to fine-tune a wide range of behavioral and physiological processes. To study the effect of environmental LD conditions on pre-adult fitness components, we used two dark-dwelling sympatric species of ants (the night active Camponotus compressus and the day active Camponotus paria), which normally develop underground and have fairly long pre-adult developmental time.

Results
Our results suggest that ants develop fastest as pre-adults when maintained under constant light (LL), followed closely by 12:12 hr light/dark (LD), and then constant darkness (DD). While light exposure alters developmental rates of almost all stages of development, the overall pre-adult development in LL is speeded-up (relative to DD) by ~37% (34 days) in C. compressus and by ~35% (31 days) in C. paria. In LD too, development is faster (relative to DD) by ~29% (26 days) in C. compressus and by ~28% (25 days) in C. paria. Pre-adult viability of both species is also higher under LL and LD compared to DD. While pre-adult development time and viability is enhanced in LL and LD, clutch-size undergoes reduction, at least in C. compressus.

Conclusion
Exposure to light enhances pre-adult fitness in two dark-dwelling species of Camponotus by speeding-up development and by enhancing viability. This suggests that social ants use environmental light/dark cycles to modulate key life history traits such as pre-adult development time and viability.
Comparative metagenomics of Daphnia symbionts
Authors: Qi Weihong , Nong Guang , Preston James F , Ben-Ami Frida , Ebert Dieter 
Published: August 2009

Abstract

Background
Shotgun sequences of DNA extracts from whole organisms allow a comprehensive assessment of possible symbionts. The current project makes use of four shotgun datasets from three species of the planktonic freshwater crustaceans Daphnia: one dataset from clones of D. pulex and D. pulicaria and two datasets from one clone of D. magna. We analyzed these datasets with three aims: First, we search for bacterial symbionts, which are present in all three species. Second, we search for evidence for Cyanobacteria and plastids, which had been suggested to occur as symbionts in a related Daphnia species. Third, we compare the metacommunities revealed by two different 454 pyrosequencing methods (GS 20 and GS FLX).

Results
In all datasets we found evidence for a large number of bacteria belonging to diverse taxa. The vast majority of these were Proteobacteria. Of those, most sequences were assigned to different genera of the Betaproteobacteria family Comamonadaceae. Other taxa represented in all datasets included the genera Flavobacterium, Rhodobacter, Chromobacterium, Methylibium, Bordetella, Burkholderia and Cupriavidus. A few taxa matched sequences only from the D. pulex and the D. pulicaria datasets: Aeromonas, Pseudomonas and Delftia. Taxa with many hits specific to a single dataset were rare. For most of the identified taxa earlier studies reported the finding of related taxa in aquatic environmental samples. We found no clear evidence for the presence of symbiotic Cyanobacteria or plastids. The apparent similarity of the symbiont communities of the three Daphnia species breaks down on a species and strain level. Communities have a similar composition at a higher taxonomic level, but the actual sequences found are divergent. The two Daphnia magna datasets obtained from two different pyrosequencing platforms revealed rather similar results.

Conclusion
Three clones from three species of the genus Daphnia were found to harbor a rich community of symbionts. These communities are similar at the genus and higher taxonomic level, but are composed of different species. The similarity of these three symbiont communities hints that some of these associations may be stable in the long-term.