bluuebunny/crossref_metadata_2025 huggingface dataset:
Toxicity in three dogs from accidental oral administration of a topical endectocide containing moxidectin and imidacloprid
Authors: See AM , McGill SE , Raisis AL , Swindells KL
Published: July 2009

Three dogs were presented with a history of oral administration of a topical endectocide containing imidacloprid and moxidectin. They were diagnosed with imidacloprid and moxidectin intoxication, having ingested doses ranging from 7.5 to 1.4 mg/kg of imidacloprid and 1.9 to 2.8 mg/kg of moxidectin. The three dogs were affected to different degrees of severity, but all displayed signs of ataxia, generalised muscle tremors, paresis, hypersalivation and disorientation. Temporary blindness occurred in two cases. The three dogs were tested for the presence of the multi‐drug resistance 1 gene deletion, which can cause an increased sensitivity to the toxic effects of moxidectin, and were found to be negative. Treatment included gastrointestinal decontamination, intravenous fluid therapy and benzodiazepines to control muscle tremors. All three dogs made a complete recovery within 48 h of ingestion.
Transcutaneous ultrasound over the right flank to diagnose mid‐ to late‐pregnancy in the dairy cow
Authors: Hunnam JC , Parkinson TJ , McDougall S
Published: July 2009

Objective To investigate the practical application and image quality of transcutaneous ultrasonography across the right flank for the diagnosis of mid‐ to late‐gestation in cattle.

Procedure Dairy cows of known pregnancy status were used to establish criteria for the identification of mid‐ to late‐stage pregnancy by transcutaneous ultrasonography. Factors involved in the practical application of transcutaneous ultrasound for routine use in pregnancy diagnosis in dairy cattle were also examined.

Results Transcutaneous ultrasound, using a 3.5‐MHz sector transducer applied over the caudodorsal right flank fold, allowed rapid and detailed visualisation of bovine pregnancy (i.e. fetus, fetal fluids, placentomes and/or fetal membranes) and could be used to establish criteria for the diagnosis of pregnancy. The commonly available cattle holding facilities of the herringbone dairy, rotary herringbone dairy, AI race or crush, and walk‐through dairy all allow safe access to the right flank of a dairy or beef cow. However, transcutaneous scanning over the right flank is difficult in modern rotary turnstile dairies.

Conclusion A 3.5‐MHz sector transducer applied over the caudodorsal right flank fold allows detailed visualisation of the bovine fetus in most types of cattle‐holding facilities. Further investigation of the sensitivity and specificity of this technique over the entire gestation period and its possible use in ageing of the bovine fetus is merited.
The Clinical Spectrum of Labile Hypertension: A Management Dilemma
Authors: Mann Samuel J.
Published: July 2009

Although the management of the labile component of blood pressure elevation is a problem often encountered by clinicians, there is a paucity of information available to guide therapeutic decisions. This review discusses the clinical relevance of blood pressure lability, the limitations of current knowledge, and possible directions for future research and clinical management.
Review of current treatment of sacral chordoma
Authors: Chen Kang‐wu , Yang Hui‐lin , Kandimalla Yugandhar , Liu Jia‐yong , Wang Gen‐lin
Published: July 2009

Chordoma is a relatively rare, locally aggressive tumor which is known to arise from embryonic remnants of the notochord and to occur exclusively along the spinal axis, with a predilection for the sacrum. Although chordoma typically presents as a single lesion, a few cases of metastasis have been reported and the prognosis of such patients may be poor. Chordomas are slowly growing tumors with insidious onset of symptoms, making early diagnosis difficult. Recent improvements in imaging have provided valuable information for early diagnosis. The optimal treatment for sacral chordoma is en bloc sacral resection with wide surgical margins. Improvement in surgical techniques has widened the opportunities to provide effective treatment. However, the effects of adjuvant treatment options are still both unclear and controversial. Substantial progress has been made in the study of molecular‐targeted therapy. The authors review the current surgical and adjuvant treatment modalities, including molecular‐targeted therapy, available for management of sacral chordoma.
Clinical imaging characteristics of herniation pits of the femoral neck
Authors: Gao Zhen‐hua , Yin Jun‐qiang , Ma Ling , Wang Jin , Meng Quan‐fei
Published: July 2009

Objective:  To discuss imaging features of radiographs, computed tomography (CT), magnetic resonance imaging (MRI) and radionuclide imaging of the herniation pit of the femoral neck and their implications for pathogenesis.

Methods:  Twenty‐seven patients with 31 herniation pits of the femoral neck were analyzed. All patients were examined by plain radiographs, 18 by CT, 16 by MRI, and 8 by radionuclide imaging.

Results:  Thirty‐one herniation pits located in the anterior part of the femoral neck or the base of the femoral head were round, oval or ‘8’‐shaped subcortical defects. The pits were usually seen as mild radiolucent areas on radiographs, soft‐tissue attenuation with a thin sclerotic rim and a focal cortical perforation on CT and three different signal intensities on MRI. Only one of eight pits revealed mild focal increased uptake on bone radionuclide scans.

Conclusion:  The occurrence of a herniation pit of the femoral neck correlates closely with the particulars of the structure of the hip joint and corresponding mechanical forces. Round or oval subcortical defects surrounded by a thin sclerotic rim in the superior lateral part of the femoral neck or the anterior lateral base of the femoral head, which are usually normal on radionuclide imaging and have focal cortical perforations on CT, are specific signs for diagnosing herniation pits of the femoral neck.
Soft tissue balancing in total hip arthroplasty for patients with adult dysplasia of the hip
Authors: Wu Xing , Lou Lie‐ming , Li Shao‐hua , Wu Wei‐ping , Cai Zheng‐dong
Published: July 2009

Objective:  To summarize our surgical experience of release and balance of soft tissues around the hip in total hip arthroplasty (THA) for patients with adult dysplasia of the hip (ADH).

Methods:  From January 2001 to January 2006, 29 adult patients with dysplastic hips (31 hips) were included in this study. Among them, there were 19 women and 10 men, aged from 38 to 65 years. According to the Crowe classification system, there were 8 type I, 12 type II, 6 type III and 5 type IV. THA was performed via a lateral approach. All acetabular cups were reconstructed at the original anatomic location through soft tissue releasing around the hip to restore limb length, and techniques of balance of soft tissue were applied to extend the strength of the hip abductor and improve its function.

Results:  All patients had restoration of limb length (range, 1.5–4.5 cm). One postoperative dislocation occurred due to slight enlargement of the angle of abduction of the acetabulum. At 1.5‐year follow‐up (mean, 3.2 years) in 29 patients, the Harris score had increased from 42.6 preoperatively to 85.4. All hips were pain free with good function.

Conclusion:  In order to restore the anatomic structure and physiologic function of the affected hip, the technique of release and balance of soft tissues around the hip should be applied cautiously in arthroplasty of ADH.
Evaluation of biocompatibility of a pectin/polyvinyl alcohol composite hydrogel as a new nucleus material
Authors: Yao Nv‐zhao , Huang Cao , Jin Da‐di
Published: July 2009

Objective:  To evaluate the biocompatibility of a new kind of prosthetic nucleus: a pectin/polyvinyl alcohol composite (CoPP) hydrogel.

Methods:  According to Chinese national standard GB/‐T16886 documents, the toxicity of the CoPP prosthetic nucleus material was examined by cytotoxicity, sensitization, Ames, mice marrow micronucleus, chromosome aberration test of mammalian cell and implantation tests.

Results:  Cell growth was similar in the CoPP culture and control groups. No significant difference was found between the CoPP culture and control groups at each time point (P > 0.05). The cell proliferation rate was greater than 100%. In accordance with the relationship between cytotoxicity to proliferation rate, it was confirmed that the cytotoxicity of CoPP was 0 grade. Mice had no allergic reaction when injected with an extract of CoPP. A reverse mutation test with Salmonella typhimurium showed that no significant effect on the number of histidine revertants of TA97, TA98, TA100 and TA102 strains after CoPP was added. The micronucleus rate in bone marrow cells was less than 5%; there was no significant difference compared with the negative control group (P > 0.05). The rate of chromosome aberration was less than 5%; no significant difference was found between the CoPP culture and the control groups. All experimental animal wounds achieved primary healing without exudation, infection or sinus formation. On macroscopic observation, no abscess or hematoma formed at the implantation site.

Conclusion:  The CoPP prosthetic nucleus has good biocompatibility and can potentially be used as an implant material.
Ecology and evolution of antibiotic resistance
Authors: Baquero F. , Alvarez‐Ortega C. , Martinez J. L.
Published: July 2009

The evolution of bacterial pathogens towards antibiotic resistance is not just a relevant problem for human health, but a fascinating example of evolution that can be studied in real time as well. Although most antibiotics are natural compounds produced by environmental microbiota, exposure of bacterial populations to high concentrations of these compounds as the consequence of their introduction for human therapy (and later on for farming) a few decades ago is a very recent situation in evolutionary terms. Resistance genes are originated in environmental bacteria, where they have evolved for millions of years to play different functions that include detoxification, signal trafficking or metabolic functions among others. However, as the consequence of the strong selective pressure exerted by antimicrobials at clinical settings, farms and antibiotic‐contaminated natural ecosystems, the selective forces driving the evolution of these potential resistance determinants have changed in the last few decades. Natural ecosystems contain a large number of potential resistance genes; nevertheless, just a few of them are currently present in gene‐transfer units and disseminated among pathogens. Along the review, the processes implied in this situation and the consequences for the future evolution of resistance and the environmental microbiota are discussed.
Global comparisons of beta diversity among mammals, birds, reptiles, and amphibians across spatial scales and taxonomic ranks
Authors: QIAN Hong
Published: July 2009

Abstract  Beta diversity is the change in species composition among areas in a geographic region. The proportion of species shared between two areas often decreases when the distance separating them increases, leading to an increase in beta diversity. This study compares beta diversity among four classes of terrestrial vertebrates (mammals, birds, reptiles, and amphibians) at both regional (biogeographic realm) and global extents, using the same sets of faunal sample units for all four groups in each comparison. Beta diversity is lower for the two endothermic taxa (birds and mammals) than for the two ectothermic taxa (reptiles and amphibians) in all six biogeographic realms examined. When the four taxa in the six biogeographic realms are combined, beta diversity at the species rank is higher than that of the genus rank by a factor of 1.24, and is higher than that of the family rank by a factor of 1.85. The ratio of beta diversity at the genus rank to that at the family rank is 1.50. Beta diversity is slightly higher for ecoregions of 5000–99,999 km2 than for ecoregions of 100,000–5,000,000 km2.
Estimating ancestral distributions of lineages with uncertain sister groups: a statistical approach to Dispersal–Vicariance Analysis and a case using Aesculus L. (Sapindaceae) including fossils
Authors: HARRIS A.J. , XIANG Qiu‐Yun (Jenny)
Published: July 2009

Abstract  We propose a simple statistical approach for using Dispersal–Vicariance Analysis (DIVA) software to infer biogeographic histories without fully bifurcating trees. In this approach, ancestral ranges are first optimized for a sample of Bayesian trees. The probability P of an ancestral range r at a node is then calculated as where Y is a node, and F(rY) is the frequency of range r among all the optimal solutions resulting from DIVA optimization at node Y, t is one of n topologies optimized, and Pt is the probability of topology t. Node Y is a hypothesized ancestor shared by a specific crown lineage and the sister of that lineage “x”, where x may vary due to phylogenetic uncertainty (polytomies and nodes with posterior probability <100%). Using this method, the ancestral distribution at Y can be estimated to provide inference of the geographic origins of the specific crown group of interest. This approach takes into account phylogenetic uncertainty as well as uncertainty from DIVA optimization. It is an extension of the previously described method called Bayes‐DIVA, which pairs Bayesian phylogenetic analysis with biogeographic analysis using DIVA. Further, we show that the probability P of an ancestral range at Y calculated using this method does not equate to pp*F(rY) on the Bayesian consensus tree when both variables are <100%, where pp is the posterior probability and F(rY) is the frequency of range r for the node containing the specific crown group. We tested our DIVA‐Bayes approach using Aesculus L., which has major lineages unresolved as a polytomy. We inferred the most probable geographic origins of the five traditional sections of Aesculus and of Aesculus californica Nutt. and examined range subdivisions at parental nodes of these lineages. Additionally, we used the DIVA‐Bayes data from Aesculus to quantify the effects on biogeographic inference of including two wildcard fossil taxa in phylogenetic analysis. Our analysis resolved the geographic ranges of the parental nodes of the lineages of Aesculus with moderate to high probabilities. The probabilities were greater than those estimated using the simple calculation of pp*F(ry) at a statistically significant level for two of the six lineages. We also found that adding fossil wildcard taxa in phylogenetic analysis generally increased P for ancestral ranges including the fossil's distribution area. The ΔP was more dramatic for ranges that include the area of a wildcard fossil with a distribution area underrepresented among extant taxa. This indicates the importance of including fossils in biogeographic analysis. Exmination of range subdivision at the parental nodes revealed potential range evolution (extinction and dispersal events) along the stems of A. californica and sect. Parryana.
Review of plant biogeographic studies in Brazil
Authors: FIASCHI Pedro , PIRANI José R.
Published: July 2009

Abstract Molecular phylogenetic studies have become a major area of interest in plant systematics, and their impacts on historical biogeographic hypotheses are not to be disregarded. In Brazil, most historical biogeographic studies have relied on animal phylogenies, whereas plant biogeographic studies have largely lacked a phylogenetic component, having a limited utility for historical biogeography. That country, however, is of great importance for most biogeographic studies of lowland tropical South America, and it includes areas from a number of biogeographic regions of the continent. Important biogeographic reports have been published as part of phylogenetic studies, taxonomic monographs, and regional accounts for small areas or phytogeographic domains, but the available information is subsequently scattered and sometimes hard to find. In this paper we review some relevant angiosperm biogeographic studies in Brazil. Initially we briefly discuss the importance of other continents as source areas for the South American flora. Then we present a subdivision of Brazil into phytogeographic domains, and we cite studies that have explored the detection of biogeographic units (areas of endemism) and how they are historically related among those domains. Examples of plant taxa that could be used to test some biogeographic hypotheses are provided throughout, as well as taxa that exemplify several patterns of endemism and disjunction in the Brazilian angiosperm flora.
The Damage Tolerance
of a Sandwich Panel Containing a Cracked Honeycomb
Core
Authors: Alonso I.
Quintana , Fleck N.
A.
Published: July 2009

The tensile fracture strength of a sandwich panel, with a center-cracked core made from an elastic-brittle diamond-celled honeycomb, is explored by analytical models and finite element simulations. The crack is on the midplane of the core and loading is normal to the faces of the sandwich panel. Both the analytical models and finite element simulations indicate that linear elastic fracture mechanics applies when a K-field exists on a scale larger than the cell size. However, there is a regime of geometries for which no K-field exists; in this regime, the stress concentration at the crack tip is negligible and the net strength of the cracked specimen is comparable to the unnotched strength. A fracture map is developed for the sandwich panel with axes given by the sandwich geometry. The effect of a statistical variation in the cell-wall strength is explored using Weibull theory, and the consequences of a stochastic strength upon the fracture map are outlined.
Dynamic Analysis of Laminated Composite Coated Beams Carrying Multiple Accelerating Oscillators Using a Coupled Finite Element-Differential Quadrature Method
Authors: Eftekhari S. A. , Farid M. , Khani M.
Published: July 2009

In this paper, a numerical algorithm using a coupled finite element-differential quadrature (DQ) method is proposed for the dynamic analysis of laminated composite coated beams subjected to a stream of accelerating oscillators. The finite element method with cubic Hermitian interpolation functions is used to discretize the spatial domain. The DQ method is then employed to discretize the time domain. The resulting set of algebraic equations can be solved by either direct methods or iterative methods. It is revealed that the DQ method stands out in numerical accuracy, as well as in computational efficiency, over the well-known standard finite difference schemes, such as the Newmark, Wilson θ, Houbolt, and central difference methods, for the cases considered. Furthermore, in the numerical examples, the effects of various parameters having something to do with the title problem, such as lamina thickness, orientation of the coats, arrival time intervals, velocities, and accelerations of the oscillators on the dynamic behavior of the system, are investigated. The technique presented in this investigation is general and can be easily applied to any time-dependent problem.
Innovations in Design Through Transformation: A Fundamental Study of Transformation Principles
Authors: Singh Vikramjit , Skiles Stewart M. , Krager Jarden E. , Wood Kristin L. , Jensen Dan , Sierakowski Robert
Published: July 2009

The act of creating a new product, system, or process is an innovation; the result of excogitation, study and experimentation. It is an inductive and/or deductive process. The inductive process involves studying systems that exist, for example, in nature, patents and products, and inducing from the behavior of these systems elemental features for innovating novel products. The deductive process involves deducing such aspects from hypothetical concepts and situations where systems or products could exist. By the application of a combined inductive and deductive approach, this paper reports on a methodology for the creation of innovative products with a broader functional repertoire than traditional designs. This breed of innovative products is coined as transformers, transforming into different configurations or according to different states. Current design theory lacks a systematic methodology for the creation of products that have the ability to transform. This paper identifies analogies in nature, patents, and products along with hypothesizing the existence of such products in different environments and situations. Transformation design principles are extracted by studying key design features and functional elements that make up a transforming product. These principles are defined and categorized according to their roles in general transformations. The principles and categorizations are then validated and applied to conceptualize transforming products as part of an innovative design process.
Thermal Therapy in Urologic Systems: A Comparison of Arrhenius and Thermal Isoeffective Dose Models in Predicting Hyperthermic Injury
Authors: He Xiaoming , Bhowmick Sankha , Bischof John C.
Published: July 2009

The Arrhenius and thermal isoeffective dose (TID) models are the two most commonly used models for predicting hyperthermic injury. The TID model is essentially derived from the Arrhenius model, but due to a variety of assumptions and simplifications now leads to different predictions, particularly at temperatures higher than 50°C. In the present study, the two models are compared and their appropriateness tested for predicting hyperthermic injury in both the traditional hyperthermia (usually, 43–50°C) and thermal surgery (or thermal therapy/thermal ablation, usually, >50°C) regime. The kinetic parameters of thermal injury in both models were obtained from the literature (or literature data), tabulated, and analyzed for various prostate and kidney systems. It was found that the kinetic parameters vary widely, and were particularly dependent on the cell or tissue type, injury assay used, and the time when the injury assessment was performed. In order to compare the capability of the two models for thermal injury prediction, thermal thresholds for complete killing (i.e., 99% cell or tissue injury) were predicted using the models in two important urologic systems, viz., the benign prostatic hyperplasia tissue and the normal porcine kidney tissue. The predictions of the two models matched well at temperatures below 50°C. At higher temperatures, however, the thermal thresholds predicted using the TID model with a constant R value of 0.5, the value commonly used in the traditional hyperthermia literature, are much lower than those predicted using the Arrhenius model. This suggests that traditional use of the TID model (i.e., R=0.5) is inappropriate for predicting hyperthermic injury in the thermal surgery regime (>50°C). Finally, the time-temperature relationships for complete killing (i.e., 99% injury) were calculated and analyzed using the Arrhenius model for the various prostate and kidney systems.
Characterization of
Young’s Modulus of Nanowires on Microcantilever
Beams
Authors: Lilley Carmen
M. , He Jin
Published: July 2009

A new approach to measure the elastic modulus of nanowires is presented in this paper using a nanowire and a microcantilever beam composite system. The mechanical behavior of a nanowire-microcantilever beam structure under electrostatic actuation was studied using the finite element method, and a comparison of the resonance frequencies for a nanowire-microcantilever composite beam structure and a microcantilever beam only is presented. The test system can be optimized by introducing arrays of nanowires to increase the resonance frequency difference between the microcantilever beams and the nanowire array microbeam structures.
Anisotropic Materials Behavior Modeling Under Shock Loading
Authors: Lukyanov Alexander A.
Published: July 2009

In this paper, the thermodynamically and mathematically consistent modeling of anisotropic materials under shock loading is considered. The equation of state used represents the mathematical and physical generalizations of the classical Mie–Grüneisen equation of state for isotropic material and reduces to the Mie–Grüneisen equation of state in the limit of isotropy. Based on the full decomposition of the stress tensor into the generalized deviatoric part and the generalized spherical part of the stress tensor (Lukyanov, A. A., 2006, “Thermodynamically Consistent Anisotropic Plasticity Model,” Proceedings of IPC 2006, ASME, New York; 2008, “Constitutive Behaviour of Anisotropic Materials Under Shock Loading,” Int. J. Plast., 24, pp. 140–167), a nonassociated incompressible anisotropic plasticity model based on a generalized “pressure” sensitive yield function and depending on generalized deviatoric stress tensor is proposed for the anisotropic materials behavior modeling under shock loading. The significance of the proposed model includes also the distortion of the yield function shape in tension, compression, and in different principal directions of anisotropy (e.g., 0 deg and 90 deg), which can be used to describe the anisotropic strength differential effect. The proposed anisotropic elastoplastic model is validated against experimental research, which has been published by Spitzig and Richmond (“The Effect of Pressure on the Flow Stress of Metals,” Acta Metall., 32, pp. 457–463), Lademo et al. (“An Evaluation of Yield Criteria and Flow Rules for Aluminium Alloys,” Int. J. Plast., 15(2), pp. 191–208), and Stoughton and Yoon (“A Pressure-Sensitive Yield Criterion Under a Non-Associated Flow Rule for Sheet Metal Forming,” Int. J. Plast., 20(4–5), pp. 705–731). The behavior of aluminum alloy AA7010 T6 under shock loading conditions is also considered. A comparison of numerical simulations with existing experimental data shows good agreement with the general pulse shape, Hugoniot elastic limits, and Hugoniot stress levels, and suggests that the constitutive equations perform satisfactorily. The results are presented and discussed, and future studies are outlined.
Flow of a Biomagnetic Visco-Elastic Fluid in a Channel With Stretching Walls
Authors: Misra J. C. , Shit G. C.
Published: July 2009

The flow of a visco-elastic fluid in a channel with stretching walls under the action of an externally applied magnetic field generated by a magnetic dipole was studied in this paper. As per an experimental report, the variation in magnetization M of the fluid with temperature T was approximated as a linear equation of state M=K1T, where K1 is a constant called the pyromagnetic coefficient. In this investigation the model used is that of Walter’s liquid B fluid, which includes the effect of fluid visco-elasticity. By introducing appropriate nondimensional variables, the problem is reduced to solving a coupled nonlinear system of ordinary differential equations subject to a set of boundary conditions. The problem is solved by developing a suitable numerical technique based on finite difference approach. Computational results concerning the variation in the velocity, pressure and temperature fields, skin friction and the rate of heat transfer with magnetic field strength, Prandtl number, and blood visco-elasticity are presented graphically. The results presented reveal that the velocity of blood in the normal physiological state can be lowered by applying a magnetic field of sufficient intensity. The study bears the promise of important applications in controlling the flow of blood during surgery and also during treatment of cancer by therapeutic means when it involves magnetic drug targeting (hyperthemia).
Theory of Images in Spherical-Layered Axisymmetric Viscous Hydrodynamics
Authors: Aderogba K.
Published: July 2009

A spherical drop of viscosity μ(1) and radius a1 is surrounded by a spherical shell of viscosity μ(2), internal radius a1, and external radius a2, beyond which there is an unbounded matrix fluid of viscosity μ(3). An arbitrary axisymmetric singularity acts inside or outside the viscous spherical shell. It is established that the Stokes’ stream function induced in this heterogeneous medium is explicitly expressible solely in terms of the corresponding stream function for the unperturbed homogeneous unbounded medium. As an application of the general solution, it is shown that there exists a homogeneous spherical drop of viscosity μ and radius a2, which is equivalent to the spherical drop of viscosity μ(1) and radius a1, surrounded by the spherical shell of viscosity μ(2) and outer radius a2. A new formula is also established for the effective viscosity of a multiphase medium comprising an incompressible fluid of viscosity μ(3) in which are embedded N small identical spherical drops of viscosity μ(1), surrounded by spherical shells of viscosity μ(2), assuming that the interference effects of these coated spherical drops are negligible, and that their arrangement is axisymmetrical. The corresponding two-dimensional results are also presented, by slightly modifying the three-dimensional results.
An Invariant Analysis of the Bending of Three Edge-Bonded Dissimilar Plates
Authors: Aderogba K.
Published: July 2009

A representation theorem is proved for the solution of the problem of two perfectly bonded isotropic semi-infinite plates under the influence of an arbitrary vertical load located in the midplane of the interior of one of them. Its function is to show that if the deflection of an unbounded isotropic plate under the influence of an arbitrary vertical load is known, then the corresponding deflections for two perfectly bonded isotropic semi-infinite plates are explicitly determinable, solely, and compactly in terms of the known deflection. Indeed, whatever the nature of the mechanism of loading is, the induced bending moments and shears in the two bonded plates are determinable by the process of differentiation only. A systematic repeated application of the theorem then yields a well-structured series solution when the arbitrary vertical load is arbitrarily located in a compound plate comprising two semi-infinite dissimilar isotropic plates separated by another dissimilar isotropic plate strip of finite breadth. As an application, we determine the effective elastic constants of a compound plate comprising a homogeneous isotropic plate in which a finite number of isotropic parallel plate strips of small breadths are embedded at such distances apart that their interaction effects may be taken as independent of one another.
The M-Integral Description for a Brittle Plane Strip With Two Cracks Before and After Coalescence
Authors: Yi-Feng Hu , Yi-Heng Chen
Published: July 2009

In this paper we extend the M-integral concept (Eshelby, J. D., 1956, The Continuum Theory of Lattice Defects, Solid State Physics, F. Seitz and D. Turnbull, eds., Academic, New York, pp. 79–141; Eshelby, J. D., 1970, The Energy Momentum Tensor in Continuum Mechanics, Inelastic Behavior of Solids, M. F. Kanninen, ed., McGraw-Hill, New York, pp. 77–115; Eshelby, J. D., 1975, “The Elastic Energy-Momentum Tensor,” J. Elast., 5, pp. 321–335; Knowles, J. K., and Sternberg, E., 1972, “On a Class of Conservation Laws in Linearized and Finite Elastostatics,” Arch. Ration. Mech. Anal., 44, pp. 187–211; Budiansky, B., and Rice, J. R., 1973, “Conservation Laws and Energy Release Rates,” ASME J. Appl. Mech., 40, pp. 201–203; Freund, L. B., 1978, “Stress Intensity Factor Calculations Based on a Conservation Integral,” Int. J. Solids Struct., 14, pp. 241–250; Herrmann, G. A., and Herrmann, G., 1981, “On Energy Release Rates for a Plane Cracks,” ASME J. Appl. Mech., 48, pp. 525–530; King, R. B., and Herrmann, G., 1981, “Nondestructive Evaluation of the J- and M-Integrals,” ASME J. Appl. Mech., 48, pp. 83–87) to study the degradation of a brittle plan strip caused by irreversible evolution: the cracks coalescence under monotonically increasing loading. Attention is focused on the change of the M-integral before and after coalescence of two neighborly located cracks inclined each other. The influences of different orientations of the two cracks and different coalescence paths connecting the two cracks on the M-integral are studied in detail. Finite element analyses reveal that different orientations of the two cracks lead to different critical values of the M-integral at which the coalescence occurs. It is concluded that the M-integral does play an important role in the description of the damage extent and damage evolution. However, it only provides some outside variable features. This means that the complete failure mechanism due to damage evolution cannot be governed by a single parameter MC as proposed by Chang and Peng, 2004, “Use of M integral for Rubbery Material Problems Containing Multiple Defects,” J. Eng. Mech., 130(5), pp. 589–598. It is found that there is an inherent relation between the M-integral and the reduction of the effective elastic moduli as the orientation of one crack varies, i.e., the larger the M-integral is, the larger the reduction is. Of great significance is that the M-integral is inherently related to the change of the total potential energy for a damaged brittle material regardless of the detailed damage features or damage evolution. Therefore, this provides a useful and convenient experimental technique to measure the values of M-integral for a damaged brittle material from initial damage to final failure without use of many stain gages (King, R. B., and Herrmann, G., 1981, “Nondestructive Evaluation of the J- and M-Integrals,” ASME J. Appl. Mech., 48, pp. 83–87).
Derivation of a Damage Sensitive Feature Using the Haar Wavelet Transform
Authors: Nair K. Krishnan , Kiremidjian Anne S.
Published: July 2009

In this paper, a damage sensitive feature based on the wavelet transform of the vibration signal is derived. The theoretical aspects of wavelet decomposition of vibration signals are presented. It is shown that the energies of the wavelet coefficients at appropriate scales can be used as damage sensitive features. Expressions for the energies of wavelet coefficients using the Haar wavelet basis function are derived for a single degree and a multidegree of freedom system. It is shown that the energies of the wavelet coefficients extracted at higher scales are functions of the physical parameters of the system and the loading function. Finally, the migration of damage sensitive feature vectors with damage is illustrated for the ASCE Benchmark Structure.
The Dynamic Compressive Response of an Open-Cell Foam Impregnated With a Non-Newtonian Fluid
Authors: Dawson M. A. , McKinley G. H. , Gibson L. J.
Published: July 2009

The response of a reticulated, elastomeric foam filled with colloidal silica under dynamic compression is studied. Under compression beyond local strain rates on the order of 1 s−1, the non-Newtonian, colloidal silica-based fluid undergoes dramatic shear thickening and then proceeds to shear thinning. In this regime, the viscosity of the fluid is large enough that the contribution of the foam and the fluid-structure interaction to the stress response of the fluid-filled foam can be neglected. An analytically tractable lubrication model for the stress-strain response of a non-Newtonian fluid-filled, reticulated, elastomeric foam under dynamic compression between two parallel plates at varying instantaneous strain rates is developed. The resulting lubrication model is applicable when the dimension of the foam in the direction of fluid flow (radial) is much greater than that in the direction of loading (axial). The model is found to describe experimental data well for a range of radius to height ratios (∼1–4) and instantaneous strain rates of the foam (1 s−1 to 4×102 s−1). The applicability of this model is discussed and the range of instantaneous strain rates of the foam over which it is valid is presented. Furthermore, the utility of this model is discussed with respect to the design and development of energy absorption and blast wave protection equipment.
Axisymmetric Body-Force Fields in Elastodynamics of Transversely Isotropic Media
Authors: Eskandari-Ghadi Morteza , Pak Ronald Y. S.
Published: July 2009

In this paper, a complete elastodynamic solution for axisymmetric problems under axial body-forces in terms of two retarded potential functions in transversely isotropic media is extended to the case of general torsionless axisymmetry. Allowing for both axial and radial distributed internal loads through the use of an extra potential, the new solution retains its completeness via the theory of repeated wave equations. By virtue of its analytical design, the formulation can be reduced to the corresponding elastostatic case by simply suppressing the time-dependence of its potentials as well as the case of isotropy. In the limiting case of the latter material condition, the proposed representation for elastostatic problem degenerates to a recent extension of Love’s potential function.
Change Propagation Analysis in Complex Technical Systems
Authors: Giffin Monica , de Weck Olivier , Bounova Gergana , Keller Rene , Eckert Claudia , Clarkson P. John
Published: July 2009

Understanding how and why changes propagate during engineering design is critical because most products and systems emerge from predecessors and not through clean sheet design. This paper examines a large data set from industry including 41,500 change requests that were generated during the design of a complex sensor system spanning a period of 8 years. In particular, the networks of connected parent, child, and sibling changes are resolved over time and mapped to 46 subsystem areas of the sensor system. These change networks are then decomposed into one-, two-, and three-node motifs as the fundamental building blocks of change activity. A statistical analysis suggests that only about half (48.2%) of all proposed changes were actually implemented and that some motifs occur much more frequently than others. Furthermore, a set of indices is developed to help classify areas of the system as acceptors or reflectors of change and a normalized change propagation index shows the relative strength of each area on the absorber-multiplier spectrum between −1 and +1. Multipliers are good candidates for more focused change management. Another interesting finding is the quantitative confirmation of the “ripple” change pattern previously proposed. Unlike the earlier prediction, however, it was found that the peak of cyclical change activity occurred late in the program driven by rework discovered during systems integration and functional testing.
Controlled Vacuum Seeding as a Means of Generating Uniform Cellular Distribution in Electrospun Polycaprolactone (PCL) Scaffolds
Authors: Chen Ming , Michaud Heather , Bhowmick Sankha
Published: July 2009

A major challenge encountered in using electrospun scaffolds for tissue engineering is the non-uniform cellular distribution in the scaffold with increasing depth under normal passive seeding conditions. Because of the small surface pores, typically few microns in diameter, cells tend to congregate and proliferate on the surface much faster compared to penetrating the scaffold interior. In order to overcome this problem, we used a vacuum seeding technique on polycaprolactone electrospun scaffolds while using NIH 3T3 fibroblasts as the model cell system. This serves as a precursor to the bilayer skin model where the fibroblasts would be residing at an intermediate layer and the keratinocytes would be on the top. Vacuum seeding was used in this study to enhance fibroblasts seeding and proliferation at different depths. Our results show that the kinetics of cell attachment and proliferation were a function of varying vacuum pressure as well as fiber diameter. Cell attachment reached a maxima somewhere between 2–8 in. Hg vacuum pressure and fell for lower vacuum pressures presumably because of cell loss through the filtration process. Cell proliferation and collagen secretion over five days indicated that vacuum pressure did not affect cellular function adversely. We also compared the combined impact of scaffold architecture (400 nm versus 1100 nm average diameter fiber scaffolds) and vacuum pressure. At a given pressure, more cells were retained in the 400 nm scaffolds compared to 1100 nm scaffolds. In addition, the cell intensity profile shows cell intensity peak shift from the top to the inner layers of the scaffold by lowering the vacuum pressure from 0 in. Hg to 20 in. Hg. For a given vacuum pressure the cells were seeded deeper within the 1100 nm scaffold. The results indicate that cells can be seeded in electrospun scaffolds at various depths in a controlled manner using a simple vacuum seeding technique. The depth of seeding is a function of pressure and scaffold fiber diameter.
Optimal Partitioning and Coordination Decisions in Decomposition-Based Design Optimization
Authors: Allison James T. , Kokkolaras Michael , Papalambros Panos Y.
Published: July 2009

The solution of complex system design problems using decomposition-based optimization methods requires determination of appropriate problem partitioning and coordination strategies. Previous optimal partitioning techniques have not addressed the coordination issue explicitly. This article presents a formal approach to simultaneous partitioning and coordination strategy decisions that can provide insights on whether a decomposition-based method will be effective for a given problem. Pareto-optimal solutions are generated to quantify tradeoffs between the sizes of subproblems and coordination problems as measures of the computational costs resulting from different partitioning and coordination strategies. Promising preliminary results with small test problems are presented. The approach is illustrated on an electric water pump design problem.
Operation and Kinematic Analysis of a Cam-Based Infinitely Variable Transmission
Authors: Lahr Derek , Hong Dennis
Published: July 2009

In this paper, the operation and analysis of a novel, highly configurable, infinitely variable transmission of the ratcheting drive type is presented. This particular drive uses a cam and a number of cam followers rotatably mounted to a carrier plate to generate an oscillatory motion in an equal number of planet gears. A number of indexing clutches are then used to rectify this motion into a rotational output. A full description of the mechanism, including its components, operation, and kinematic equations, are presented. There are a number of inversions of this device, and their characteristics and limitations are discussed. In addition, a method is presented to select the most suitable inversion, gearing, and maximum follower velocity for a given set of requirements.
ResQuake: A Tele-Operative Rescue Robot
Authors: Moosavian S. Ali A. , Kalantari Arash , Semsarilar Hesam , Aboosaeedan Ehsan , Mihankhah Ehsan
Published: July 2009

The design procedure of ResQuake as a tele-operative rescue robot and its dynamics analysis, manufacturing procedure, control system, and slip estimation for performance improvement are discussed. First, the general task to be performed by the robot is defined, and various mechanisms to form the basic structure of the robot are discussed. Choosing the appropriate mechanisms, geometric dimensions, and mass properties are detailed to develop kinematic and dynamic models for the system. Next, the strength of each component is analyzed to finalize its shape, and the mechanism models are presented. Then, the control system is briefly described, which includes the operator’s PC as the master processor, and the laptop installed on the robot as the slave processor. Finally, slip coefficients of tracks are identified and validated by experimental tests to improve the system tracking performance. ResQuake has participated with distinction in several rescue robot leagues.
Fractal Dimension and Multifractal Spectra of INGAN/GAN Self-Assembled Quantum Dots Films
Authors: Lam K. T.
Published: July 2009

The surface shape and microstructure of semiconductor thin films, especially nanometer thin films, greatly influence such physical characteristics as the electricity, magnetic and optics nature to the thin films, etc. In this work, we use the fractal dimension and multifractal spectra to study the surface morphology of annealed InGaN/GaN self-assembled quantum dot (SAQD) films. Samples used in this study were grown on (0001)-oriented sapphire (Al2O3) substrates in a vertical low-pressure metalorganic chemical vapor deposition (MOCVD) reactor with a high-speed rotation disk. The fractal dimension and multifractal spectra can be used to describe the influence of different annealing conditions on surface characterization. Fractal analysis reveals that both the average surface roughness and root-mean-square roughness of nanostructure surfaces decreased after thermal annealing. It can be seen that a smoother surface was obtained after an annealing temperature of 800°C, and it implies that the surface roughness of this case is minimum in all tests. The results of this paper also include a mathematical model to describe the observation of fractal and multifractal characteristics in semiconductor nanostructure films.
Mechanical Properties and Fracture Mechanism of CF Flat Braided Composites With Dispersed Carbon Nanofibers in the Matrix
Authors: Aly-Hassan Mohamed S. , Kobayashi Yuka , Nakai Asami , Hamada Hiroyuki , Hatta Hiroshi
Published: July 2009

In this research, laminated flat braided carbon fabrics were performed via flattening tubular braided fabrics with braiding angle of ±45° by applying carefully compressive loads laterally on the tubular fabrics. Then, carbon fiber reinforced epoxy matrix composites were fabricated from the above-mentioned biaxial fabrics with and without uniformly dispersed carbon nanofibers throughout the epoxy matrix. Three loading percentages of carbon nanofibers (specifically, 0.5, 1, and 2 wt%) were dispersed in the matrix of the composites to enhance the matrix and interlaminar/inter-ply properties. The influence of matrix and interlaminar properties improvements on the in-plane tensile and shear response of the laminated flat braided composites was clarified via conducting of ±45° laminates tensile tests. The experimental results of tensile tests revealed that the tensile and in-plane shear properties as well as the fracture behavior of the composites are substantially influenced by the incorporation of the dispersed carbon nanofibers in the matrix of the composites. A pulsed thermography technique was used to inspect the occurrence of the delamination after the fracture under tensile loadings. The thermal wave image and logarithmic temperature-time curves of the pulsed thermography inspection illustrated that the composites with dispersed carbon nanofibers rendered higher interlaminar properties than that of composites without nanofibers. The main conclusion of this research can be summarized that dispersion of carbon nanofibers through the epoxy matrix of laminated flat braided composites not only enhanced the matrix properties but also improved the interphase morphology between the composite plies that maximized the stress transfer of the composites.