bluuebunny/crossref_metadata_2025 huggingface dataset:
The relation of cyber aggression to peer social competence in the classroom for children in China
Authors: Washington Robert , Cohen Robert , Berlin Kristoffer S. , Hsueh Yeh , Zhou Zongkui
Published: July 2018

Engaging in cyber aggression has been shown to be associated with negative psychosocial adjustment for both the victim and the aggressor for U.S. samples. Of particular interest to the present research was how engaging in cyber aggression related to classroom peer social competence for children in China. Participants were 494 students (Boys = 278; Girls = 216), Grades 3–6, attending an elementary school in Wuhan, China. A path analysis was performed using peer nominations for classroom aggression (overt and relational) and self‐reports of cyber aggression to predict: intra‐individual social competence (global self‐worth, loneliness, peer optimism); relationships (number of classroom mutual friends); and group level social competence (peer nominations for sociability behaviors and for popularity). Consistent with previous research on children, extent of engaging in cyber aggression was associated with negative intra‐individual and relationship classroom social competence measures. Unlike other studies, extent of cyber aggression was not associated with group level evaluations. Overt aggression was found to relate to classroom social competence in a similar fashion as reported for U.S. children; relational aggression showed a different pattern. The findings highlight the importance of examining the unique associations of types and forms of aggression to social competence, particularly in relation to culture.
Describing soil quality with aggregate index for Msange irrigation scheme of Tanzania
Authors: Nyamsha D. , Kansal M. L.
Published: July 2018

Soil quality is an important and integral aspect of soil health which is defined as the continued capacity of the soil to function as a living system within the ecosystem and land use boundaries. It refers to the capacity of soil to supply nutrients, maintain suitable biotic habitat and resist degradation. This study focuses on describing the soil quality through aggregate index termed as Soil Quality Index (SQI). The assessment of soil quality involves physical and chemical soil parameters along with the local climatic conditions and the experts’ opinion. The proposed aggregation method utilizes three scoring functions; ‘more is better’, ‘less is better’ and ‘optimum’ for which the score is interpreted either as very low, low, medium, high or very high. The methodology has been applied to Msange irrigation scheme which falls under semi‐arid climate conditions of Tanzania. The results show that the average SQI in the Msange irrigation scheme is 0.565 for the silt loam soil and can be classified as medium quality. In order to improve the soil quality and hence the land productivity, one should improve the organic matter contents, available water and nutrients availability to the soil. It is hoped that this study will be a baseline study on soil quality evaluation for effective agricultural practices.
Temporal variability and time compression of sediment yield in small Mediterranean catchments: impacts for land and water management
Authors: Smetanová A. , Le Bissonnais Y. , Raclot D. , Pedro Nunes J. , Licciardello F. , Le Bouteiller C. , Latron J. , Rodríguez Caballero E. , Mathys N. , Klotz S. , Mekki I. , Gallart F. , Solé Benet A. , Pérez Gallego N. , Andrieux P. , Moussa R. , Planchon O. , Santos J. M. , Alshihabi O. , Chikhaoui M. , Follain S.
Published: July 2018

Increased soil erosion, pressure on agricultural land, and climate change highlight the need for new management methods to mitigate soil loss. Management strategies should utilize comparable data sets of long‐term soil erosion monitoring across multiple environments. Adaptive soil erosion management in regions with intense precipitation requires an understanding of inter‐annual variability in sediment yield (SY) at regional scales. Here, a novel approach is proposed for analysing regional SY. We aimed to (i) investigate factors controlling inter‐ and intra‐annual SY, (ii) combine seasonality and time compression analyses to explore SY variability and (iii) discuss management implications for different Mediterranean environments. Continuous SY measurements totalling 104 years for eight small catchments were used to describe SY variability, which ranged from 0 to 271 t/ha/year and 0 to 116 t/ha/month. Maximum SY occurs in spring to summer for catchments with oceanic climates, while semi‐arid or dry summer climates experience SY minimums. We identified three time compression patterns at each time scale. Time compression was most intense for catchments with minimum SY in spring to summer. Low time compression was linked to very high soil loss, low run‐off and sediment production thresholds, and high connectivity. Reforestation, grassland and terracing changed SY magnitudes and time compression, but failed to reduce SY for large storm events. Periods with a high probability of high SY were identified using a combination of intra‐annual SY variability, seasonality analysis, and time compression analysis. Focusing management practices on monthly flow events, which account for the majority of SY, will optimise returns in Mediterranean catchments.
The long‐term soil phosphorus balance across Chinese arable land
Authors: Ma J. , Liu Y. , He W. , He P. , Haygarth P. M. , Surridge B. W. J. , Lei Q. , Zhou W.
Published: July 2018

Quantifying temporal and spatial variation of soil phosphorus (P) input, output and balance across Chinese arable land is necessary for better P management strategies. Here, we address this challenge using a soil P budget to analyse the soil P balance in arable land across the whole of China, for the period 1980–2012. Results indicated that the total P input to soil increased from 22.5 kg P/ha in 1980 to 79.1 kg P/ha in 2012. However, the total P output from soil only increased from 17.9 kg P/ha in 1980 to 36.9 kg P/ha in 2012. Therefore, the average net soil P surplus in China increased from 4.6 kg P/ha in 1980 to 42.1 kg P/ha in 2012. Our research found great variation in soil P balances across different regions. Soil P balance varied between regions with the order of southeast (SE) > north central (NC) and the middle and lower reaches of Yangtze River (MLYR) > southwest (SW) > northwest (NW) > northeast (NE). Phosphorus that has accumulated in agricultural soil across China could theoretically meet crop P demands for approximately 4.8–12.0 yrs, depending on the bioavailability of P stored in soils. Increasing the return rates of manure and straw could substantially reduce the demand for fertilizer‐P. This paper represents a basis for more targeted, regionally informed P fertilizer recommendations in Chinese soils.
Sider's Ontologese Introduction Instructions
Authors: Wrigley Wesley
Published: July 2018

In response to Hirsch's deflationary arguments, Sider attempts to introduce a special Ontologese quantifier to preserve the substantivity of fundamental debates in metaphysics. He claims that this strategy can be effected by two distinct means, one of which is a list of instructions for metaphysicians, which he argues suffice to give the new quantifier a meaning that carves nature at the joints. I argue that these instructions will not allow someone to start speaking Ontologese if their prior language is sufficiently deviant with respect to it, and that natural languages may be in just such a position.
Assessment of the red blood cell proteome in a dog with unexplained hemolytic anemia
Authors: Black Victoria L. , Heesom Kate , Whittington Fran , Davis Sean , Tasker Séverine , Adamantos Sophie , Davidson Andrew D.
Published: July 2018

A 7‐year‐old female neutered Jack Russell Terrier was presented to Langford Vets, the University of Bristol, with a history of chronic intermittent lethargy. Investigations and clinical course were compatible with hereditary hemolysis due to a red blood cell membrane defect. Proteomics was used to explore protein alterations in the presence of a hypothesized red blood cell membrane protein deficiency. Proteomic analysis revealed downregulation of the band 3, and alpha‐ and beta‐adducin proteins, and alterations in the red blood cell proteome consistent with previous reports of changes due to the presence of reticulocytosis and ongoing hemolysis. The spectrum of protein alterations identified in the affected dog may be homologous to a band 3 protein deficiency secondary to hereditary spherocytosis, as described in people.
Thrombocytosis and central nervous system involvement in a case of canine acute megakaryoblastic leukemia
Authors: Rochel Daphné , Abadie Jérôme , Robveille Cynthia , Déqueant Bérengère , Dagher Elie , Roux Françoise , Jaillardon Laetitia
Published: July 2018

This case report presents a 14‐month‐old female Poodle mix with acute megakaryoblastic leukemia based on a marked thrombocytosis, abnormal platelet morphology, circulating dwarf megakaryocytes, and blast cells in the blood. Bone marrow abnormalities included dysmegakaryopoiesis dygranulopoiesis, and an increased number of blast cells was observed in the blood. Extensive leukemic involvement was also found in the liver, spleen, lymph nodes, lungs, kidneys, and brain. The cytopathologic features of the abnormal circulating cells were highly suggestive of being megakaryocytic in origin, which was supported by negative myeloperoxidase staining and positive von Willebrand factor staining on immunocytochemistry (ICC). The neoplastic cells were also CD61 positive and had variable von Willebrand factor expression on ICC. Although there were only 25% blast cells in the bone marrow, which theoretically supported myelodysplastic syndrome, the hypothesis that this case represented acute myeloid leukemia of megakaryoblastic origin was confirmed by the continuous increase in circulating blast cell numbers during follow‐up visits and the extensive leukemic involvement of parenchymal organs.
Process Evaluation of a Participatory, Multimodal Intervention to Improve Evidence‐Based Care in Long‐Term Care Settings
Authors: Edwards Nancy C. , Smith Higuchi Kathryn
Published: July 2018

Background

Evidence‐based improvements in long‐term care (LTC) are challenging due to human resource constraints.

Aims

To evaluate implementation of a multimodal, participatory intervention aimed at improving evidence‐based care.

Methods

Using a qualitative descriptive design, we conducted and inductively analyzed individual interviews with staff at midpoint and end‐point to identify action plan implementation processes and challenges. The 9‐month intervention engaged professional and unregulated staff in an on‐site workshop and provided support for their development and implementation of site‐specific action plans.

Results

Ten of 12 enrolled sites participated for the full study period. Interviews were conducted with 44 and 69 participants at midpoint and end‐point, respectively. Seven of 10 sites focused their action plan on team functioning and communication. Main achievements described at end‐point were improved team communication, better staff engagement, and improved teamwork. Internal and external supports for action plan implementation were described as critical for success.

Discussion

Three factors influenced change: vertically and horizontally linked teams, external facilitator support for action plan implementation, and coaching by Best Practice Coordinators that emphasized organizational change and normalization of evidence‐based practice.

Implications

Team functioning and communication are forerunners of clinical practice changes in LTC. An off‐site model of facilitation is promising and may provide a more efficient means to reach a wider array of LTC settings.

Linking Evidence to Action

Practice changes need engagement of all staff.
Do we have to consider acidosis induced by exercise as deleterious in sickle cell disease?
Authors: Chatel Benjamin , Messonnier Laurent A. , Bendahan David
Published: July 2018

New Findings

What is the topic of this review?

The aim of this review is to discuss the potential involvement of exercise‐induced acidosis in the commonly reported complications in sickle cell disease.

What advances does it highlight?

Blood acidosis appears clearly to be a risk factor for HbS polymerization, red blood cell sickling and the occurrence of vaso‐occlusive crisis and could induce hyperkalaemia‐related complications. It could be of great interest to try to avoid blood acidosis during exercise, which could be done using some alkalinizing solutions or adapted endurance training interventions.

Sickle cell disease (SCD) is an inherited haemoglobin (Hb) disorder and the most common monogenic disease in the world. The root cause of this pathology is the synthesis of an abnormal Hb (HbS) that polymerizes in deoxygenated conditions, leading to the sickling of red blood cells. Acidosis is well recognized as a promoter of HbS polymerization and therefore red blood cell sickling. Indeed, it has been shown in vitro that the relative amount of sickled red blood cells increases markedly from 1% at pH 7.4 to >90% at pH 7.0. Nevertheless, no study has directly tested whether exercise‐induced acidosis could favour SCD complications. Greater knowledge of the effects of metabolic acidosis during exercise could be of importance given the conclusions reached in several studies that proposed regular physical exercise as a therapeutic strategy in the management of SCD. In this review, we discuss the potential consequences of exercise‐induced acidosis for the pathophysiology of SCD. We also propose some potential therapeutic interventions with the aim of reducing the metabolic acidosis related to exercise.
Angiogenesis in the lung
Authors: Eldridge Lindsey , Wagner Elizabeth M.
Published: July 2018

Both systemic (tracheal and bronchial) and pulmonary circulations perfuse the lung. However, documentation of angiogenesis of either is complicated by the presence of the other. Well‐documented angiogenesis of the systemic circulations have been identified in asthma, cystic fibrosis, chronic thromboembolism and primary carcinomas. Angiogenesis of the vasa vasorum, which are branches of bronchial arteries, is seen in the walls of large pulmonary vessels after a period of chronic hypoxia. Documentation of increased pulmonary capillaries has been shown in models of chronic hypoxia, after pneumonectomy and in some carcinomas. Although endothelial cell proliferation may occur as part of the repair process in several pulmonary diseases, it is separate from the unique establishment of new functional perfusing networks defined as angiogenesis. Identification of the mechanisms driving the expansion of new vascular beds in the adult needs further investigation. Yet the growth factors and molecular mechanisms of lung angiogenesis remain difficult to separate from underlying disease sequelae.

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There's a New Cycle in Town
Authors: Nordeen Craig A. , Langston Lee S.
Published: July 2018

The promises of increased efficiency, simplicity, and high power density are driving the current research focus on rotating detonation engines (RDEs). An engine that uses detonation rather than deflagration could have some key advantages. If harnessed in a gas turbine or rocket, detonation could reduce the need for some expensive hardware, lighten engine weight and increase power output and efficiency. Today, variants of the RDE as a combustor for gas turbines, rockets, and scramjets are being explored at the Air Force Research Laboratory (AFRL), Naval Research Laboratory, Naval Postgraduate School, and the Department of Energy. Similar work is being conducted in several other countries. This study provides a deeper look into RDEs.
Range of Thermal Treatment Upon the Mechanical Characteristics of PLLA Coiled Stents
Authors: Welch Tre R. , Eberhart Robert C. , Chuong Cheng-Jen
Published: July 2018

Stents have been used as a medical device to restore blood flow in stenosed vessels. During this process of stent expansion, the balloon and stent could damage the endothelial lining of the vascular wall [Grewe, Farb] and alter the mechanical stress states of various tissue components. The subsequent tissue re-growth and vascular remodeling have been implicated among the causes leading to restenosis. Stent designs vary over a wide range from materials used, geometric shapes, fabrication methods, treatments, among many other parameters. There are many different stent designs. We have developed an internally coiled, furled helical PLLA fiber stent at our institution [Su 03, Zilberman 02, 04, 05]. We have previously shown the effect of 62°C thermal annealing on the expansive characteristics of this stent [Welch 08].
The Effects of Wearing a Transradial Myoelectric Prosthesis on Range of Motion of the Elbow
Authors: Carey Stephanie L. , Highsmith M. Jason , Dubey Rajiv V.
Published: July 2018

Prosthetists know that the height and design of the trim lines of a transradial prosthesis can affect the range of motion of the elbow and the forearm. However, the extent of trim line effects has not been documented. The purpose of this study, as part of a larger range of motion study, was to determine the differences between ranges of motion of elbow with and without the effects of the trim lines of the transradial myoelectric prosthesis.
Load Transfer Along the Bone-Dental Implant Interface
Authors: Faegh Samira , Müftü Sinan
Published: July 2018

Endosseous dental implants are used as prosthetic treatment alternatives for treating partial edentulism [1]. Excellent long term results and high success rates have been achieved using dental implants during the past decades. Further improvements in implant protocols will include immediate loading, patient specific implants, applications for patients with extreme bone loss and extreme biting habits such as bruxism. The implant designs available in the market vary in size, shape, materials and surface characteristics [2], and address some of these concerns. An important factor in the implant design is the load transfer from the implant to bone during occlusal loading.[2,3] Load transfer starts along the bone-implant interface, and is affected by the loading type, material properties of the implant and prosthesis, implant geometry, surface structure, quality and quantity of the surrounding bone, and nature of the bone-implant interface [4]. While many studies using the finite element method (FEM) have been carried out [2–5], a systematic investigation of the load transfer at the bone implant interface, and the effects of various parameters that make the implant contour is lacking. The goal of this paper is to investigate one aspect of this multivariable problem, namely the effect of external implant threads on the load transfer along the bone-implant interface.
Design of Microcontroller Based Test Bench for a Multichannel Integrated Biosensor Chip
Authors: Zhang Xin , Li Yingxin , Zhang Yulong , Chen Zuhui , Liu Shi , Nelson Richard D. , LaRue John C.
Published: July 2018

The planar microelectrode array (pMEA) is an important tool for non-invasive recording in the fields of neuroscience and biosensing. It can be used for extra-cellular measurement of the induced voltage on an electrode underneath a cell upon the occurrence of an action potential. With the principle of capacitive coupling, the sensed electrode signal amplitudes typically range between 100 μV and 1 mV, depending on the cell type. Due to the small amplitude of original neural signals, signal conditioning and processing microelectronics units are necessary to integrate with the pMEA sensor for achievement of best measurement performance. Introducing fully customized ASIC into the microelectrode array substrate provides an efficient solution, which establishes the possibility of creating the biosensor system on chip (SoC) with a large number of sensing-sites for simultaneous measurement without introducing significant noise from the signal conditioning and processing circuitry [1]. In this research work, we have developed a fully customized biosensor chip for sensing the propagation of action potentials. With the paralleled multiple sub-circuits, this prototype multi-site planar microelectrode array biosensor integrates 24 (4 × 6) microelectrode array sensing sites, 24 parallel analog neural signal buffers and a shared OTA based high gain amplifier on the same substrate. Figure 1 depicts the biosensor chip architecture and the functional blocks of the biosensor system setup. The prototyped biosensor chip was fabricated by MOSIS using AMI C5 0.5μm, double poly, triple metal layer CMOS technology. The electroless gold plating process post-CMOS processing and packaging techniques were applied to the biosensor chip to promote the biocompatibility and stability in the aqueous cell culture environment. To interface the biosensor chip with PC, a microcontroller based electronic system is necessary to implement the functions of A/D conversion, biosensor chip control signal generation, digital signal processing and data/command communication between biosensor chip and GUI software running on PC. In this research work, a Motorola ColdFire MCF5307 microcontroller based electronic system was setup to serve as the interface between the biosensor chip and PC, which realized the full functions listed above. The firmware running on MCF5307 microcontroller was implemented with ColdFire assembly language where on the PC client Matlab platform was chosen to simply the software design work.
Thermal Treatment Effects Upon the Degradation Characteristics of PLLA Coiled Stents
Authors: Welch Tre R. , Eberhart Robert C. , Chuong Cheng-Jen
Published: July 2018

Stents are a medical device used to restore blood flow in stenosed vessels. During the process of stent expansion, the balloon and stent could damage the endothelial lining of the vascular wall and alter the mechanical stress states of various tissue components. The evolution of stents has progressed from bare metal stents to drug eluting stents or stents coated with drugs such as Sirolimus. Drug eluting stents are currently used to address the restenosis event that occurs after implantation. These stents have been effective but late stent thrombosis has been an emerging issue with drug eluting stents. Bioresorbable stents have emerged as a potential candidate for drug eluting stents. Su 03 has shown drug-loading PLLA with curcumin can be used as an anti-inflammatory agent. We have developed an internally coiled, furled helical PLLA fiber stent at our institution [Su 03, Zilberman 02, 04, 05]. We have previously shown the effect of 62°C thermal annealing on the expansive characteristics of this stent [Welch 08].
Localized Brain Tissue Cooling for Use During Intracranial Thrombectomy
Authors: Merrill Thomas L. , Merrill Denise R. , Akers Jennifer E.
Published: July 2018

The primary goal of current ischemic stroke treatment is quickly restoring blood perfusion. Recanalization is linked to improved neurological outcomes [1]. Resulting tissue necrosis, however, following a stroke has two causes: 1) ischemic injury and 2) reperfusion injury. Therefore, development of neuroprotective agents specifically beneficial against reperfusion injury are required.
Diffussion Tensor Imaging of the Arterial Collagen Architecture
Authors: Ghazanfari S. , Driessen-Mol A. , Kanters F. M. W. , Baaijens F. P. T. , Bouten C. V. C.
Published: July 2018

Collagen is largely responsible for the mechanical behavior of the artery [1]. The collagen architecture can be visualized using different methods. We evaluated a novel imaging methodology which is fast, non-invasive and non-destructive.
Revised Scaling Relationship for Backflow Distance Along an Infusion Catheter
Authors: García José Jaime , Smith Joshua H.
Published: July 2018

Convection-enhanced delivery (CED) is a means to deliver therapeutic agents directly into brain tissue for the treatment of brain tumors and other disorders of the central nervous system, such as Parkinson’s disease. Recent clinical trials have shown limited efficacy of this procedure, with poor distribution of the infused agent being the primary obstacle [1]. One of the challenges with improving the distribution is the effect of backflow, in which the infused fluid preferentially flows along the outside of the catheter toward the surface of the brain rather than through the tissue toward the desired region for delivery.
On the Uptake of Ultrasmall Superparamagnetic Particles of Iron Oxide and Biomechanical Wall Stress in Abdominal Aortic Aneurysms
Authors: Doyle Barry , Richards Jennifer , Semple Scott , MacGillivray Tom , Gray Calum , Chalmers Roderick , Garden O. James , Dransfield Ian , Newby David , Hoskins Peter
Published: July 2018

Abdominal aortic aneurysms (AAAs) remain a significant cause of death in the Western world with over 15,000 deaths per year in the US linked to AAA rupture. There is a general belief among the clinical and engineering community that improved methods of risk prediction are needed. The growth and expansion of AAAs over time is thought to be associated with the mechanobiological interactions within the diseased AAA wall. The stresses and strains induced in the wall by the internal blood pressure trigger increased protease activity and turnover of the extracellular matrix (ECM), thus enabling degradation and expansion of the wall. Inflammatory cells also control collagen synthesis and inflammation can reduce the tensile strength of the wall, thus contributing to the likelihood of rupture. Recently, important work by Richards et al. [1] showed that AAAs with specific sites of focal inflammation have threefold higher growth rates than AAAs with non-specific inflammation.
A New 3D Reconstruction Method for Human Coronary Bifurcations for Shear Stress Computations
Authors: Gijsen Frank , Schuurbiers Hans , Schaap Michiel , van der Steen Anton , Wentzel Jolanda
Published: July 2018

Atherosclerosis is characterized by lipid accumulation in the arterial wall, followed by an inflammatory response. Plaque formation is generally observed near bifurcations in coronary arteries. The composition of atherosclerotic plaques depends on the location, and it was hypothesized that blood flow induced shear stress influences plaque composition2. To study the impact of shear stress on atherosclerotic disease in human coronary arteries, we developed a technique that enables us to generate 3D lumen reconstruction based on multislice computer tomography (MSCT) and intravascular ultrasound (IVUS).We describe two approaches to generate 3D reconstructions of human coronary artery bifurcations and apply them to coronary segments with bifurcations. We will evaluate the effect on shear stress distribution and its relationship to wall thickness.
Shear Stress Mediates Angiogenic Gene Expression in a Microfluidic Tumor Vascular Model
Authors: Buchanan Cara F. , Voigt Elizabeth , Szot Christopher S. , Freeman Joseph W. , Vlachos Pavlos P. , Rylander Marissa Nichole
Published: July 2018

While research has shown that the fluid mechanics of the tumor vasculature reduce transport and uptake of therapeutics, the underlying role of these stresses in regulating tumor-endothelial cell signaling and neovascularization are not well understood. Understanding the reciprocal interaction between endothelial and tumor cells to mediate angiogenesis, and the effect of fluid shear on this process, may offer insight into the development of improved treatment modalities to control highly vascularized tumors. We have previously shown that breast cancer cells cultured under 2D, static conditions with endothelial cells significantly increase expression of pro-angiogenic factors vascular endothelial growth factor (VEGF) and angiopoietin 2 (ANG2) [1]. These preliminary results motivated the investigation of tumor-endothelial cross-talk under 3D, dynamic co-culture conditions.
Effect of Wall Shear Stress on Abdominal Aortic Aneurysm Expansion: Study With Longitudinal Patient Images
Authors: Zambrano B. , Dupay A. , Jaberi F. , Lee W. , Baek S.
Published: July 2018

Abdominal Aortic Aneurysms (AAA), a focal enlargement of abdominal aorta, is a form of vascular diseases that affects large part of the population. It can cause the mortality up to 90% of the cases when it ruptures. Currently, the best known treatment to reduce risk is open surgery or endovascular repair. Since the risk of such surgery repair is high, in most patients with AAAs< 55mm in its maximum diameter the surgical treatment is postponed. An effort to enhance the accuracy of the risk assessment and to prevent AAA’s growth and rupture is being made, but the mechanisms promoting AAAs growth are still largely unknown. AAAs can be affected by different factors, among those, hemodynamics is known to play important roles in AAA initiation and progression. Particularly, the wall shear stress is believed to contribute to AAA expansion and rupture. For the present study, we use geometries constructed from longitudinal CT images obtained during AAA follow-up studies and investigate relations between multiple hemodynamics factors with local expansion of AAAs.
3D Stress Computations in Atherosclerotic Arteries: The Influence of Axial Image Resolution
Authors: Nieuwstadt Harm A. , Akyildiz Ali C. , Speelman Lambert , Wentzel Jolanda J. , Virmani Renu , van der Steen Ton , Gijsen Frank
Published: July 2018

Sudden rupture of vulnerable atherosclerotic plaques is a major contributing cause of acute myocardial infarctions and ischemic strokes [1]. A vulnerable plaque is defined as a plaque with a large necrotic core and a thin fibrous cap. In order to characterize, and further comprehend, plaque vulnerability from a mechanical point of view, the rupture process can be seen as a mechanical process which occurs when the tensile stress in the fibrous cap exceeds its material strength. Biomechanical stress modeling of plaques using the Finite Element Method (FEM) has been used as a tool to provide insight in the stress distribution in plaques and shows potential to facilitate identification of vulnerable plaques using novel biomechanics-based risk-stratification criteria [1, 2, 3]. Accurate stress prediction using computational modeling depends on a number of factors including material models, computational methods, initial conditions and accurate reconstruction of the plaque geometry from ex vivo or in vivo imaging. The latter received limited attention and lacks a critical evaluation. In case of 3D modeling, the arterial geometry is typically reconstructed by stacking MRI or histology slices in the axial direction and interpolating the geometry without consensus on minimal requirements of inter slice distance (axial sampling distance) [4]. Due to time constraints during the imaging procedure, especially MRI suffers from a limited axial resolution (typically an inter slice distance of 1–3 mm), which might compromise accurate geometry reconstruction which could in turn influence resulting stress computations.
Non-Invasive Molecular Imaging of Shear Stress-Induced Endothelial Activation and Atherosclerotic Plaque Vulnerability
Authors: Van der Heiden K. , Groen H. C. , Evans P. C. , Speelman L. , Gijsen F. , de Jong M. , van der Steen A. F. W. , Wentzel J. J.
Published: July 2018

Atherosclerosis is a lipid- and inflammation driven disease of the larger arteries and is found at specific locations in the arterial tree, i.e. at branches and bends where endothelial cells are exposed to low and low, oscillatory shear stress. Shear stress, the frictional force acting on the endothelial cells as a result of the blood flow, affects endothelial physiology. It determines the location of atherosclerotic lesion development as low and low, oscillatory shear stress induce pro-inflammatory transcription factors but reduce expression and/or activity of anti-inflammatory transcription factors in endothelial cells, rendering the vascular wall vulnerable for inflammation. Consequently, in the presence of atherosclerotic risk factors, such as hypercholesterolemia and diabetes, atherosclerotic lesion development can occur. Although the relationship between low and low, oscillatory shear stress and the prevalence of atherosclerosis has been recognized for several decades, insight into the mechanisms underlying this relationship is still incomplete. The correlation between shear stress and endothelial inflammation was demonstrated by in vitro experiments, in which cultured endothelial cells were exposed to specific flow profiles, and confirmed in vivo by gene expression pattern studies at atherosclerosis-susceptible sites. However, the relationship was not substantiated by direct causal in vivo evidence. Therefore, we developed a method to change the local shear stress field in mice in vivo and studied its effect on the endothelial molecular pathways and resulting atherosclerotic plaque formation. Moreover it allowed us to develop non-invasive molecular imaging strategies to detect vulnerable plaques.
Non-Invasive Calculation of Energy Loss in Pulmonary Arteries Using 4D Phase Contrast MRI Measurement
Authors: Lee Namheon , Taylor Michael D. , Hor Kan N. , Banerjee Rupak K.
Published: July 2018

The recent development of energy based endpoints, to quantify the pathophysiology of congenital heart disease such as tetralogy of Fallot (TOF), requires accurate measurement of cardiac blood flow and pressure data. Consequently, invasive cardiac catheterization is required for those measurements. In this research we used 4D phase contrast magnetic resonance imaging (PC MRI) data to determine the pressure drop non-invasively. This enables us to obtain pressure-flow variation, which, in turn, allowed us to calculate energy loss along the branch pulmonary arteries (PA). Based on our result, we believe that the hemodynamic status of the PA of a subject can be non-invasively evaluated by both pressure drop and energy loss values along the PA.
Adjoint Based Calibration of Coupled Simulation Approaches of Patient-Specific Vascular Models
Authors: Wall Wolfgang A. , Ismail Mahmoud , Maier Andreas , Gee Michael W.
Published: July 2018

In recent years, computational methods have often been utilized for a better understanding of cardiovascular systems. They can be used to analyze vascular disease development [1], predict life threatening risk factors [2], and help improve vascular treatments.
Correlation of Longitudinal Intravascular Ultrasound Data for the Clinical Assessment of Coronary Artery Disease Progression
Authors: Timmins Lucas H. , Suever Jonathan D. , Eshtehardi Parham , McDaniel Michael C. , Samady Habib , Oshinski John N. , Giddens Don P.
Published: July 2018

Virtual histology-intravascular ultrasound (VH-IVUS) has gained increasing utility in the cardiac catheterization laboratory, not only in determining underlying atherosclerotic lesion composition prior to stent placement, but also in clinical studies assessing the natural history of coronary artery disease (CAD) [1]. Furthermore, VH-IVUS has provided an excellent means of quantifying disease progression by comparing data sets collected over time (i.e., longitudinal studies) and potentially identifying rapidly progressing and potentially vulnerable plaques. One difficulty, however, in analyzing VH-IVUS derived CAD progression is the accurate co-registration of image sets collected over a period of time. Commonly, an expert VH-IVUS image reader reviews these image sets side-by-side on a display and co-registers images along the vessel main axis, herein axially co-registered, by identifying image locations relative to fiduciary anatomical markers (e.g., branches). Despite this method being the standard for analyzing CAD progression, it is limited by the inability to accurately co-register VH-IVUS data in the circumferential direction (i.e., rotating images such that their cylindrical coordinate bases coincide; herein circumferentially co-registered). Thus, a significant amount of information on focal plaque progression is lost that could provide a greater understanding of the natural evolution of CAD, the effects of various pharmaceutical agents (e.g., statins) on lesion composition changes, and the impact of local mechanical factors that induce plaque progression/regression and transformation.
The Effect of Plaque Morphology on Cap Stresses in Coronary Arteries
Authors: Akyildiz A. C. , Speelman L. , Nieuwstadt H. , Virmani R. , Wentzel J. , van der Steen A. , Gijsen F.
Published: July 2018

Atherosclerosis is a cardiovascular disease characterized by plaque formation in the vessel wall. The region of an atherosclerotic plaque separating its pathological content from the lumen is called cap. Cap rupture initiates thrombus formation and may lead to myocardial infarction and sudden death [1].
Flow System to Detect Transitional Flow Based on Pulsed Doppler Ultrasound Velocity Profiles
Authors: Ambati Narender , Biswas Dipankar , Loth Francis , Rittgers Stanley E. , Jones Steven A.
Published: July 2018

A flow circuit test rig has been constructed to determine the critical Reynolds number at which blood flow become turbulent. A Doppler ultrasound velocimeter was used in an in vitro flow system to measure the velocity of water inside a straight pipe in order to determine the critical Reynolds number (Re) at which the flow becomes transitional. Results using water as the working fluid demonstrated flow-transition to turbulence near Re = 2000 which is close to the expected value from literature. Future studies will utilize blood as the working fluid.
Modeling of Soft Tissue Property Changes Induced by Fatigue Loading
Authors: Martin Caitlin , Sun Wei
Published: July 2018

Bio-prosthetic heart valves (BHVs), with glutaraldehyde-treated bovine pericardium (GLBP) leaflets, have been used extensively to replace diseased heart valves. BHVs display superior hemodynamics to mechanical valves; however, their use is limited due to poor durability resulting from in vivo degradation and fatigue damage of the leaflets. Yet, little is known about the fatigue properties of GLBP tissue. Sun et al. [1] has previously studied the effects of fatigue on GLBP tissue specimens which were cyclically stretched up to 65×106 cycles. The fatigued GLBP specimens exhibited altered material properties and geometry (permanent set). Because fatigue experiments are very time-consuming and costly, there is a need to develop predictive models to accurately capture tissue fatigue experimental data. Furthermore, it is desirable that such tissue fatigue models could be incorporated into computational simulations to investigate the effects of complicated loading conditions, such as in BHV applications, on device durability.
Toward Improved Prediction of AAA Rupture Risk: Implementation of Feature-Based Geometry Quantification Measures Compared to Maximum Diameter Alone
Authors: Shum J. , Muluk S. C. , Doyle A. , Chandra A. , Eskandari M. , Finol E. A.
Published: July 2018

Data mining techniques are capable of extracting important relationships and correlations among large amounts of data while machine learning methodologies can utilize these correlations to generate models capable of classification and prediction. The combination of machine learning and data mining is an important contribution of the present work for two reasons: (1) given a large database of features that describe the geometry of native abdominal aortic aneurysms (AAAs), patterns and relationships in the data are derived that may not be apparent to the human eye, and (2) statistical models are generated that can classify new data and determine which features discriminate among different aneurysm populations. The objectives of this study were to use anatomically realistic AAA models to evaluate a proposed set of global geometric indices describing the size, shape and individual wall thickness of the aneurysm sac, and use a learning algorithm to develop a model that is capable of discriminating the rupture status of these aneurysms.
Human Eye Response to Blast Overpressure
Authors: Alphonse Vanessa D. , Kemper Andrew R. , Strom Brock T. , Beeman Stephanie M. , Duma Stefan M.
Published: July 2018

Each year, approximately two million people in the United States suffer eye injuries that require treatment [1]. Although it is suggested that blast overpressure can cause serious eye injuries, there is no clear evidence in the literature to support this injury mechanism. Conversely, projectile impacts have been shown to cause serious eye injuries [2, 3]. The critical question is whether blast overpressure alone can cause eye injury or if injuries are caused solely by projected material. Therefore, the purpose of the current study is to measure the intraocular pressure (IOP) of postmortem human eyes during blasts and assess injuries sustained in order to more fully understand the effect of blast overpressure on the eye.
Thermal Stress Conditioning to Induce Osteogenic Protein Expression for Bone Regeneration
Authors: Sampson Alana C. , Chung Eunna , Rylander Marissa Nichole
Published: July 2018

Although bone has the intrinsic ability to “self-heal”, there are circumstances in which its regenerative capacity is limited or compromised, such as in critical bone defects. In these cases, the lack of osteogenic proteins at the wound site can prevent healing and external stimuli may be necessary to encourage bone growth [1]. Exogenous delivery of proteins and growth factors directly to the wound has been successful in bone regeneration, but is limited by the instability of the proteins and short half-lives. As a result, administration of multiple large doses of protein is necessary to retain a beneficial protein level. Due to these disadvantages, additional methods have been investigated to supply essential proteins to the bone defect [2].
Finite Element Method Solution Uncertainty, Asymptotic Solution, and a New Approach to Accuracy Assessment
Authors: Fong Jeffrey T. , Marcal Pedro V. , Rainsberger Robert , Ma Li , Heckert N. Alan , Filliben James J.
Published: July 2018

Errors and uncertainties in finite element method (FEM) computing can come from the following eight sources, the first four being FEM-method-specific, and the second four, model-specific: (1) Computing platform such as ABAQUS, ANSYS, COMSOL, LS-DYNA, etc.; (2) choice of element types in designing a mesh; (3) choice of mean element density or degrees of freedom (d.o.f.) in the same mesh design; (4) choice of a percent relative error (PRE) or the Rate of PRE per d.o.f. on a log-log plot to assure solution convergence; (5) uncertainty in geometric parameters of the model; (6) uncertainty in physical and material property parameters of the model; (7) uncertainty in loading parameters of the model, and (8) uncertainty in the choice of the model. By considering every FEM solution as the result of a numerical experiment for a fixed model, a purely mathematical problem, i.e., solution verification, can be addressed by first quantifying the errors and uncertainties due to the first four of the eight sources listed above, and then developing numerical algorithms and easy-to-use metrics to assess the solution accuracy of all candidate solutions. In this paper, we present a new approach to FEM verification by applying three mathematical methods and formulating three metrics for solution accuracy assessment. The three methods are: (1) A 4-parameter logistic function to find an asymptotic solution of FEM simulations; (2) the nonlinear least squares method in combination with the logistic function to find an estimate of the 95% confidence bounds of the asymptotic solution; and (3) the definition of the Jacobian of a single finite element in order to compute the Jacobians of all elements in a FEM mesh. Using those three methods, we develop numerical tools to estimate (a) the uncertainty of a FEM solution at one billion d.o.f., (b) the gain in the rate of PRE per d.o.f. as the asymptotic solution approaches very large d.o.f.’s, and (c) the estimated mean of the Jacobian distribution (mJ) of a given mesh design. Those three quantities are shown to be useful metrics to assess the accuracy of candidate solutions in order to arrive at a so-called “best” estimate with uncertainty quantification. Our results include calibration of those three metrics using problems of known analytical solutions and the application of the metrics to sample problems, of which no theoretical solution is known to exist.
Virtually-Guided Certification With Uncertainty Quantification Applied to Die Casting
Authors: Shahane Shantanu , Mujumdar Soham , Kim Namjung , Priya Pikee , Aluru Narayana , Ferreira Placid , Kapoor Shiv G. , Vanka Surya
Published: July 2018

Die casting is a type of metal casting in which liquid metal is solidified in a reusable die. In such a complex process, measuring and controlling the process parameters is difficult. Conventional deterministic simulations are insufficient to completely estimate the effect of stochastic variation in the process parameters on product quality. In this research, a framework to simulate the effect of stochastic variation together with verification, validation, and uncertainty quantification is proposed. This framework includes high-speed numerical simulations of solidification, micro-structure and mechanical properties prediction models along with experimental inputs for calibration and validation. Both experimental data and stochastic variation in process parameters with numerical modeling are employed thus enhancing the utility of traditional numerical simulations used in die casting to have a better prediction of product quality. Although the framework is being developed and applied to die casting, it can be generalized to any manufacturing process or other engineering problems as well.
Experimental Calibration of a Biohydrogen Production Estimation Model
Authors: Dias Fernando G. , Vargas Jose V. C. , Yang Sam , Kava Vanessa M. , Balmant Wellington , Mariano Andre B. , Ordonez Juan C.
Published: July 2018

In this work, a dynamic physics-based model developed for the prediction of biohydrogen production in a compact tubular photobioreactor was calibrated experimentally. The spatial domain in the model was discretized with lumped control volumes, and the principles of classical thermodynamics, mass, species and heat transfer were combined to derive a system of ordinary differential equations whose solution was the temperature and mass fraction distributions across the entire system. Two microalgae species, namely, Acutodesmus obliquus and Chlamydomonas reinhardtii strain ccI25 were cultured in triplicate with different culture media via indirect biophotolysis. Experimental biomass and hydrogen concentrations were then used to adjust the specific microalgae growth and hydrogen production coefficients based on residual sum of squares and the direct search method.