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Sample records for failure swine models

  1. Engineered Swine Models of Cancer

    PubMed Central

    Watson, Adrienne L.; Carlson, Daniel F.; Largaespada, David A.; Hackett, Perry B.; Fahrenkrug, Scott C.

    2016-01-01

    Over the past decade, the technology to engineer genetically modified swine has seen many advancements, and because their physiology is remarkably similar to that of humans, swine models of cancer may be extremely valuable for preclinical safety studies as well as toxicity testing of pharmaceuticals prior to the start of human clinical trials. Hence, the benefits of using swine as a large animal model in cancer research and the potential applications and future opportunities of utilizing pigs in cancer modeling are immense. In this review, we discuss how pigs have been and can be used as a biomedical models for cancer research, with an emphasis on current technologies. We have focused on applications of precision genetics that can provide models that mimic human cancer predisposition syndromes. In particular, we describe the advantages of targeted gene-editing using custom endonucleases, specifically TALENs and CRISPRs, and transposon systems, to make novel pig models of cancer with broad preclinical applications. PMID:27242889

  2. Advancing swine models for human health and diseases.

    PubMed

    Walters, Eric M; Prather, Randall S

    2013-01-01

    Swine models are relatively new kids on the block for modeling human health and diseases when compared to rodents and dogs. Because of the similarity to humans in size, physiology, and genetics, the pig has made significant strides in advancing the understanding of the human condition, and is thus an excellent choice for an animal model. Recent technological advances to genetic engineering of the swine genome enhance the utility of swine as models of human genetic diseases.

  3. Advances in Swine Biomedical Model Genomics

    PubMed Central

    Lunney, Joan K.

    2007-01-01

    This review is a short update on the diversity of swine biomedical models and the importance of genomics in their continued development. The swine has been used as a major mammalian model for human studies because of the similarity in size and physiology, and in organ development and disease progression. The pig model allows for deliberately timed studies, imaging of internal vessels and organs using standard human technologies, and collection of repeated peripheral samples and, at kill, detailed mucosal tissues. The ability to use pigs from the same litter, or cloned or transgenic pigs, facilitates comparative analyses and genetic mapping. The availability of numerous well defined cell lines, representing a broad range of tissues, further facilitates testing of gene expression, drug susceptibility, etc. Thus the pig is an excellent biomedical model for humans. For genomic applications it is an asset that the pig genome has high sequence and chromosome structure homology with humans. With the swine genome sequence now well advanced there are improving genetic and proteomic tools for these comparative analyses. The review will discuss some of the genomic approaches used to probe these models. The review will highlight genomic studies of melanoma and of infectious disease resistance, discussing issues to consider in designing such studies. It will end with a short discussion of the potential for genomic approaches to develop new alternatives for control of the most economically important disease of pigs, porcine reproductive and respiratory syndrome (PRRS), and the potential for applying knowledge gained with this virus for human viral infectious disease studies. PMID:17384736

  4. Longitudinal hemodynamic measurements in swine heart failure using a fully implantable telemetry system.

    PubMed

    Choy, Jenny S; Zhang, Zhen-Du; Pitsillides, Koullis; Sosa, Margo; Kassab, Ghassan S

    2014-01-01

    Chronic monitoring of heart rate, blood pressure, and flow in conscious free-roaming large animals can offer considerable opportunity to understand the progression of cardiovascular diseases and can test new diagnostics and therapeutics. The objective of this study was to demonstrate the feasibility of chronic, simultaneous measurement of several hemodynamic parameters (left ventricular pressure, systemic pressure, blood flow velocity, and heart rate) using a totally implantable multichannel telemetry system in swine heart failure models. Two solid-state blood pressure sensors were inserted in the left ventricle and the descending aorta for pressure measurements. Two Doppler probes were placed around the left anterior descending (LAD) and the brachiocephalic arteries for blood flow velocity measurements. Electrocardiographic (ECG) electrodes were attached to the surface of the left ventricle to monitor heart rate. The telemeter body was implanted in the right side of the abdomen under the skin for approximately 4 to 6 weeks. The animals were subjected to various heart failure models, including volume overload (A-V fistula, n = 3), pressure overload (aortic banding, n = 2) and dilated cardiomyopathy (pacing-induced tachycardia, n = 3). Longitudinal changes in hemodynamics were monitored during the progression of the disease. In the pacing-induced tachycardia animals, the systemic blood pressure progressively decreased within the first 2 weeks and returned to baseline levels thereafter. In the aortic banding animals, the pressure progressively increased during the development of the disease. The pressure in the A-V fistula animals only showed a small increase during the first week and remained stable thereafter. The results demonstrated the ability of this telemetry system of long-term, simultaneous monitoring of blood flow, pressure and heart rate in heart failure models, which may offer significant utility for understanding cardiovascular disease progression and

  5. Longitudinal Hemodynamic Measurements in Swine Heart Failure Using a Fully Implantable Telemetry System

    PubMed Central

    Choy, Jenny S.; Zhang, Zhen-Du; Pitsillides, Koullis; Sosa, Margo; Kassab, Ghassan S.

    2014-01-01

    Chronic monitoring of heart rate, blood pressure, and flow in conscious free-roaming large animals can offer considerable opportunity to understand the progression of cardiovascular diseases and can test new diagnostics and therapeutics. The objective of this study was to demonstrate the feasibility of chronic, simultaneous measurement of several hemodynamic parameters (left ventricular pressure, systemic pressure, blood flow velocity, and heart rate) using a totally implantable multichannel telemetry system in swine heart failure models. Two solid-state blood pressure sensors were inserted in the left ventricle and the descending aorta for pressure measurements. Two Doppler probes were placed around the left anterior descending (LAD) and the brachiocephalic arteries for blood flow velocity measurements. Electrocardiographic (ECG) electrodes were attached to the surface of the left ventricle to monitor heart rate. The telemeter body was implanted in the right side of the abdomen under the skin for approximately 4 to 6 weeks. The animals were subjected to various heart failure models, including volume overload (A-V fistula, n = 3), pressure overload (aortic banding, n = 2) and dilated cardiomyopathy (pacing-induced tachycardia, n = 3). Longitudinal changes in hemodynamics were monitored during the progression of the disease. In the pacing-induced tachycardia animals, the systemic blood pressure progressively decreased within the first 2 weeks and returned to baseline levels thereafter. In the aortic banding animals, the pressure progressively increased during the development of the disease. The pressure in the A-V fistula animals only showed a small increase during the first week and remained stable thereafter. The results demonstrated the ability of this telemetry system of long-term, simultaneous monitoring of blood flow, pressure and heart rate in heart failure models, which may offer significant utility for understanding cardiovascular disease

  6. Irreversible Electroporation in a Swine Lung Model

    SciTech Connect

    Dupuy, Damian E.; Aswad, Bassam; Ng, Thomas

    2011-04-15

    Purpose: This study was designed to evaluate the safety and tissue effects of IRE in a swine lung model. Methods: This study was approved by the institutional animal care committee. Nine anesthetized domestic swine underwent 15 percutaneous irreversible electroporation (IRE) lesion creations (6 with bipolar and 3 with 3-4 monopolar electrodes) under fluoroscopic guidance and with pancuronium neuromuscular blockade and EKG gating. IRE electrodes were placed into the central and middle third of the right mid and lower lobes in all animals. Postprocedure PA and lateral chest radiographs were obtained to evaluate for pneumothorax. Three animals were sacrificed at 2 weeks and six at 4 weeks. Animals underwent high-resolution CT scanning and PA and lateral radiographs 1 h before sacrifice. The treated lungs were removed en bloc, perfused with formalin, and sectioned. Gross pathologic and microscopic changes after standard hematoxylin and eosin staining were analyzed within the areas of IRE lesion creation. Results: No significant adverse events were identified. CT showed focal areas of spiculated high density ranging in greatest diameter from 1.1-2.2 cm. On gross inspection of the sectioned lung, focal areas of tan discoloration and increased density were palpated in the areas of IRE. Histological analysis revealed focal areas of diffuse alveolar damage with fibrosis and inflammatory infiltration that respected the boundaries of the interlobular septae. No pathological difference could be discerned between the 2- and 4-week time points. The bronchioles and blood vessels within the areas of IRE were intact and did not show signs of tissue injury. Conclusion: IRE creates focal areas of diffuse alveolar damage without creating damage to the bronchioles or blood vessels. Short-term safety in a swine model appears to be satisfactory.

  7. Translational Relevance of Swine Models of Spinal Cord Injury.

    PubMed

    Schomberg, Dominic T; Miranpuri, Gurwattan S; Chopra, Abhishek; Patel, Kush; Meudt, Jennifer J; Tellez, Armando; Resnick, Daniel K; Shanmuganayagam, Dhanansayan

    2017-02-01

    Spinal cord injury (SCI) is a physically and psychologically devastating clinical condition. The typical treatment regimens of decompressive surgery and rehabilitation therapy still leave many patients with permanent disability. The development of new therapies and devices can be accelerated if relevant translational animal models are more effectively used in pre-clinical stages. Swine is a highly relevant model for SCI research, especially with respect to spine and spinal cord anatomy, spine vasculature, immune responses to injury, and functional assessments. Several spine injury models have recently been developed for swine and are beginning to be used to evaluate new therapies. Swine models of SCI offer tremendous advantages for efficient translation of pre-clinical discoveries and the development of new therapies and devices. Future swine models will also be enhanced by advances in gene-editing technology to further elucidate the complex pathophysiology associated with SCI and provide a means to engineer specific spinal pathologies.

  8. The failure of earthquake failure models

    USGS Publications Warehouse

    Gomberg, J.

    2001-01-01

    In this study I show that simple heuristic models and numerical calculations suggest that an entire class of commonly invoked models of earthquake failure processes cannot explain triggering of seismicity by transient or "dynamic" stress changes, such as stress changes associated with passing seismic waves. The models of this class have the common feature that the physical property characterizing failure increases at an accelerating rate when a fault is loaded (stressed) at a constant rate. Examples include models that invoke rate state friction or subcritical crack growth, in which the properties characterizing failure are slip or crack length, respectively. Failure occurs when the rate at which these grow accelerates to values exceeding some critical threshold. These accelerating failure models do not predict the finite durations of dynamically triggered earthquake sequences (e.g., at aftershock or remote distances). Some of the failure models belonging to this class have been used to explain static stress triggering of aftershocks. This may imply that the physical processes underlying dynamic triggering differs or that currently applied models of static triggering require modification. If the former is the case, we might appeal to physical mechanisms relying on oscillatory deformations such as compaction of saturated fault gouge leading to pore pressure increase, or cyclic fatigue. However, if dynamic and static triggering mechanisms differ, one still needs to ask why static triggering models that neglect these dynamic mechanisms appear to explain many observations. If the static and dynamic triggering mechanisms are the same, perhaps assumptions about accelerating failure and/or that triggering advances the failure times of a population of inevitable earthquakes are incorrect.

  9. Modelling the Growth of Swine Flu

    ERIC Educational Resources Information Center

    Thomson, Ian

    2010-01-01

    The spread of swine flu has been a cause of great concern globally. With no vaccine developed as yet, (at time of writing in July 2009) and given the fact that modern-day humans can travel speedily across the world, there are fears that this disease may spread out of control. The worst-case scenario would be one of unfettered exponential growth.…

  10. SWINE INFLUENZA

    PubMed Central

    Shope, Richard E.

    1931-01-01

    1. It has been possible to demonstrate, in Berkefeld filtrates of infectious material from experimental cases of swine influenza, a virus which when administered intranasally to susceptible swine induced a mild, usually afebrile illness of short duration. The changes in the respiratory tract resembled those in swine influenza but were usually much less extensive. When the filtrable virus was mixed with pure cultures of H. influenzae suis and administered to swine a disease identical clinically and pathologically with swine influenza was induced. The data presented indicate that the filtrable virus of swine influenza and H. influenzae suis act in concert to produce swine influenza and that neither alone is capable of inducing the disease. 2. One attack of swine influenza usually renders an animal immune to reinfection. Blood serum from an animal made immune in this way neutralizes infectious material from swine influenza in vitro, as shown by the failure of the mixture to produce disease in a susceptible animal. 3. The virus can be stored in a dried state or in glycerol for several weeks at least. In one instance dried material apparently retained both the virus and H. influenzas suis in viable form for a period of 54 days. 4. Fatal cases of experimental swine influenza have been observed in which H. influenzae suis was the only organism that could be cultivated from the respiratory tract. 5. Attention has been called to some features of marked similarity between epizootic swine influenzae and epidemic influenzae in man. PMID:19869924

  11. Common Cause Failure Modeling

    NASA Technical Reports Server (NTRS)

    Hark, Frank; Britton, Paul; Ring, Robert; Novack, Steven

    2015-01-01

    Space Launch System (SLS) Agenda: Objective; Key Definitions; Calculating Common Cause; Examples; Defense against Common Cause; Impact of varied Common Cause Failure (CCF) and abortability; Response Surface for various CCF Beta; Takeaways.

  12. Common Cause Failure Modeling

    NASA Technical Reports Server (NTRS)

    Hark, Frank; Britton, Paul; Ring, Rob; Novack, Steven D.

    2015-01-01

    Common Cause Failures (CCFs) are a known and documented phenomenon that defeats system redundancy. CCFS are a set of dependent type of failures that can be caused by: system environments; manufacturing; transportation; storage; maintenance; and assembly, as examples. Since there are many factors that contribute to CCFs, the effects can be reduced, but they are difficult to eliminate entirely. Furthermore, failure databases sometimes fail to differentiate between independent and CCF (dependent) failure and data is limited, especially for launch vehicles. The Probabilistic Risk Assessment (PRA) of NASA's Safety and Mission Assurance Directorate at Marshall Space Flight Center (MFSC) is using generic data from the Nuclear Regulatory Commission's database of common cause failures at nuclear power plants to estimate CCF due to the lack of a more appropriate data source. There remains uncertainty in the actual magnitude of the common cause risk estimates for different systems at this stage of the design. Given the limited data about launch vehicle CCF and that launch vehicles are a highly redundant system by design, it is important to make design decisions to account for a range of values for independent and CCFs. When investigating the design of the one-out-of-two component redundant system for launch vehicles, a response surface was constructed to represent the impact of the independent failure rate versus a common cause beta factor effect on a system's failure probability. This presentation will define a CCF and review estimation calculations. It gives a summary of reduction methodologies and a review of examples of historical CCFs. Finally, it presents the response surface and discusses the results of the different CCFs on the reliability of a one-out-of-two system.

  13. Common Cause Failure Modeling

    NASA Technical Reports Server (NTRS)

    Hark, Frank; Britton, Paul; Ring, Rob; Novack, Steven D.

    2016-01-01

    Common Cause Failures (CCFs) are a known and documented phenomenon that defeats system redundancy. CCFS are a set of dependent type of failures that can be caused by: system environments; manufacturing; transportation; storage; maintenance; and assembly, as examples. Since there are many factors that contribute to CCFs, the effects can be reduced, but they are difficult to eliminate entirely. Furthermore, failure databases sometimes fail to differentiate between independent and CCF (dependent) failure and data is limited, especially for launch vehicles. The Probabilistic Risk Assessment (PRA) of NASA's Safety and Mission Assurance Directorate at Marshal Space Flight Center (MFSC) is using generic data from the Nuclear Regulatory Commission's database of common cause failures at nuclear power plants to estimate CCF due to the lack of a more appropriate data source. There remains uncertainty in the actual magnitude of the common cause risk estimates for different systems at this stage of the design. Given the limited data about launch vehicle CCF and that launch vehicles are a highly redundant system by design, it is important to make design decisions to account for a range of values for independent and CCFs. When investigating the design of the one-out-of-two component redundant system for launch vehicles, a response surface was constructed to represent the impact of the independent failure rate versus a common cause beta factor effect on a system's failure probability. This presentation will define a CCF and review estimation calculations. It gives a summary of reduction methodologies and a review of examples of historical CCFs. Finally, it presents the response surface and discusses the results of the different CCFs on the reliability of a one-out-of-two system.

  14. Common swine models of cardiovascular disease for research and training.

    PubMed

    Crisóstomo, Verónica; Sun, Fei; Maynar, Manuel; Báez-Díaz, Claudia; Blanco, Virginia; Garcia-Lindo, Monica; Usón-Gargallo, Jesús; Sánchez-Margallo, Francisco Miguel

    2016-02-01

    Cardiovascular diseases are a major health concern and therefore an important topic in biomedical research. Large animal models allow researchers to assess the safety and efficacy of new cardiovascular procedures in systems that resemble human anatomy; additionally, they can be used to emulate scenarios for training purposes. Among the many biomedical models that are described in published literature, it is important that researchers understand and select those that are best suited to achieve the aims of their research, that facilitate the humane care and management of their research animals and that best promote the high ethical standards required of animal research. In this resource the authors describe some common swine models that can be easily incorporated into regular practices of research and training at biomedical institutions. These models use both native and altered vascular anatomy of swine to carry out research protocols, such as testing biological reactions to implanted materials, surgically creating aneurysms using autologous tissue and inducing myocardial infarction through closed-chest procedures. Such models can also be used for training, where native and altered vascular anatomy allow medical professionals to learn and practice challenging techniques in anatomy that closely simulates human systems.

  15. Myocardial infarction and intramyocardial injection models in swine.

    PubMed

    McCall, Frederic C; Telukuntla, Kartik S; Karantalis, Vasileios; Suncion, Viky Y; Heldman, Alan W; Mushtaq, Muzammil; Williams, Adam R; Hare, Joshua M

    2012-07-12

    Sustainable and reproducible large animal models that closely replicate the clinical sequelae of myocardial infarction (MI) are important for the translation of basic science research into bedside medicine. Swine are well accepted by the scientific community for cardiovascular research, and they represent an established animal model for preclinical trials for US Food and Drug Administration (FDA) approval of novel therapies. Here we present a protocol for using porcine models of MI created with a closed-chest coronary artery occlusion-reperfusion technique. This creates a model of MI encompassing the anteroapical, lateral and septal walls of the left ventricle. This model infarction can be easily adapted to suit individual study design and enables the investigation of a variety of possible interventions. This model is therefore a useful tool for translational research into the pathophysiology of ventricular remodeling and is an ideal testing platform for novel biological approaches targeting regenerative medicine. This model can be created in approximately 8-10 h.

  16. Swine as models in biomedical research and toxicology testing.

    PubMed

    Swindle, M M; Makin, A; Herron, A J; Clubb, F J; Frazier, K S

    2012-03-01

    Swine are considered to be one of the major animal species used in translational research, surgical models, and procedural training and are increasingly being used as an alternative to the dog or monkey as the choice of nonrodent species in preclinical toxicologic testing of pharmaceuticals. There are unique advantages to the use of swine in this setting given that they share with humans similar anatomic and physiologic characteristics involving the cardiovascular, urinary, integumentary, and digestive systems. However, the investigator needs to be familiar with important anatomic, histopathologic, and clinicopathologic features of the laboratory pig and minipig in order to put background lesions or xenobiotically induced toxicologic changes in their proper perspective and also needs to consider specific anatomic differences when using the pig as a surgical model. Ethical considerations, as well as the existence of significant amounts of background data, from a regulatory perspective, provide further support for the use of this species in experimental or pharmaceutical research studies. It is likely that pigs and minipigs will become an increasingly important animal model for research and pharmaceutical development applications.

  17. Acute Electrocardiographic ST Segment Elevation May Predict Hypotension in a Swine Model of Severe Cyanide Toxicity

    DTIC Science & Technology

    2012-04-21

    induced shock, 30 swine were anesthetized and monitored and then intoxicated with a continuous cyanide infusion until severe hypotension (50 % of...TOXICOLOGY INVESTIGATION Acute Electrocardiographic ST Segment ElevationMay Predict Hypotension in a Swine Model of Severe Cyanide Toxicity Tylan A...Toxicology 2012 Abstract Cyanide causes severe cardiac toxicity resulting in tachycardia, hypotension, and cardiac arrest; however, the clinical diagnosis can

  18. Failure models for textile composites

    SciTech Connect

    Cox, B.

    1995-08-01

    The goals of this investigation were to: (1) identify mechanisms of failure and determine how the architecture of reinforcing fibers in 3D woven composites controlled stiffness, strength, strain to failure, work of fracture, notch sensitivity, and fatigue life; and (2) to model composite stiffness, strength, and fatigue life. A total of 11 different angle and orthogonal interlock woven composites were examined. Composite properties depended on the weave architecture, the tow size, and the spatial distributions and strength of geometrical flaws. Simple models were developed for elastic properties, strength, and fatigue life. A more complicated stochastic model, called the `Binary Model,` was developed for damage tolerance and ultimate failure. These 3D woven composites possessed an extraordinary combination of strength, damage tolerance, and notch insensitivity.

  19. Failure models for textile composites

    NASA Technical Reports Server (NTRS)

    Cox, Brian

    1995-01-01

    The goals of this investigation were to: (1) identify mechanisms of failure and determine how the architecture of reinforcing fibers in 3D woven composites controlled stiffness, strength, strain to failure, work of fracture, notch sensitivity, and fatigue life; and (2) to model composite stiffness, strength, and fatigue life. A total of 11 different angle and orthogonal interlock woven composites were examined. Composite properties depended on the weave architecture, the tow size, and the spatial distributions and strength of geometrical flaws. Simple models were developed for elastic properties, strength, and fatigue life. A more complicated stochastic model, called the 'Binary Model,' was developed for damage tolerance and ultimate failure. These 3D woven composites possessed an extraordinary combination of strength, damage tolerance, and notch insensitivity.

  20. Transmissibility of Variant Influenza From Swine to Humans: A Modeling Approach

    PubMed Central

    Wong, Karen K.; Gambhir, Manoj; Finelli, Lyn; Swerdlow, David L.; Ostroff, Stephen; Reed, Carrie

    2015-01-01

    Background Respiratory illness was reported among humans and swine at an agricultural fair in 2011; 3 human infections with an influenza A(H3N2) variant (H3N2v) virus were confirmed. Using epidemiologic investigation data, we sought to estimate H3N2v transmissibility from swine to humans. Methods We developed a model of H3N2v transmission among swine and humans and fit it to data from a cohort of 100 agricultural club members reporting swine contact to estimate transmissibility. A sensitivity analysis was performed varying H3N2v prevalence in the club cohort. Using the best-fit transmission probability, we simulated the number of swine-acquired infections among all fair attendees. Results We estimated the best-fit probability of swine-to-human H3N2v transmission per minute of swine contact. Applying this probability to 14 910 people with swine contact at the fair, we estimate that there were 80 (95% confidence interval [CI], 40–133) H3N2v infections among persons aged <20 years and 58 (95% CI, 29–96) H3N2v infections among person aged ≥20 years. Conclusions Using early data from investigation of a new virus with unclear transmission properties, we estimated the transmissibility of H3N2v from swine to humans and the burden of H3N2v among fair attendees. Although the risk of H3N2v virus infection is small for fair attendees with minimal swine contact, large populations attend agricultural events each year, and human cases will likely occur when infected swine are present. PMID:23794727

  1. Modeling Classical Swine Fever Outbreak-Related Outcomes

    PubMed Central

    Yadav, Shankar; Olynk Widmar, Nicole J.; Weng, Hsin-Yi

    2016-01-01

    The study was carried out to estimate classical swine fever (CSF) outbreak-related outcomes, such as epidemic duration and number of infected, vaccinated, and depopulated premises, using defined most likely CSF outbreak scenarios. Risk metrics were established using empirical data to select the most likely CSF outbreak scenarios in Indiana. These scenarios were simulated using a stochastic between-premises disease spread model to estimate outbreak-related outcomes. A total of 19 single-site (i.e., with one index premises at the onset of an outbreak) and 15 multiple-site (i.e., with more than one index premises at the onset of an outbreak) outbreak scenarios of CSF were selected using the risk metrics. The number of index premises in the multiple-site outbreak scenarios ranged from 4 to 32. The multiple-site outbreak scenarios were further classified into clustered (N = 6) and non-clustered (N = 9) groups. The estimated median (5th, 95th percentiles) epidemic duration (days) was 224 (24, 343) in the single-site and was 190 (157, 251) and 210 (167, 302) in the clustered and non-clustered multiple-site outbreak scenarios, respectively. The median (5th, 95th percentiles) number of infected premises was 323 (0, 488) in the single-site outbreak scenarios and was 529 (395, 662) and 465 (295, 640) in the clustered and non-clustered multiple-site outbreak scenarios, respectively. Both the number and spatial distributions of the index premises affected the outcome estimates. The results also showed the importance of implementing vaccinations to accommodate depopulation in the CSF outbreak controls. The use of routinely collected surveillance data in the risk metrics and disease spread model allows end users to generate timely outbreak-related information based on the initial outbreak’s characteristics. Swine producers can use this information to make an informed decision on the management of swine operations and continuity of business, so that potential losses

  2. A new twist on an old idea part 2: cyclosporine preserves normal mitochondrial but not cardiomyocyte function in mini‐swine with compensated heart failure

    PubMed Central

    Hiemstra, Jessica A.; Gutiérrez‐Aguilar, Manuel; Marshall, Kurt D.; McCommis, Kyle S.; Zgoda, Pamela J.; Cruz‐Rivera, Noelany; Jenkins, Nathan T.; Krenz, Maike; Domeier, Timothy L.; Baines, Christopher P.; Emter, Craig A.

    2014-01-01

    Abstract We recently developed a clinically relevant mini‐swine model of heart failure with preserved ejection fraction (HFpEF), in which diastolic dysfunction was associated with increased mitochondrial permeability transition (MPT). Early diastolic function is ATP and Ca2+‐dependent, thus, we hypothesized chronic low doses of cyclosporine (CsA) would preserve mitochondrial function via inhibition of MPT and subsequently maintain normal cardiomyocyte Ca2+ handling and contractile characteristics. Left ventricular cardiomyocytes were isolated from aortic‐banded Yucatan mini‐swine divided into three groups; control nonbanded (CON), HFpEF nontreated (HF), and HFpEF treated with CsA (HF‐CsA). CsA mitigated the deterioration of mitochondrial function observed in HF animals, including functional uncoupling of Complex I‐dependent mitochondrial respiration and increased susceptibility to MPT. Attenuation of mitochondrial dysfunction in the HF‐CsA group was not associated with commensurate improvement in cardiomyocyte Ca2+ handling or contractility. Ca2+ transient amplitude was reduced and transient time to peak and recovery (tau) prolonged in HF and HF‐CsA groups compared to CON. Alterations in Ca2+ transient parameters observed in the HF and HF‐CsA groups were associated with decreased cardiomyocyte shortening and shortening rate. Cellular function was consistent with impaired in vivo systolic and diastolic whole heart function. A significant systemic hypertensive response to CsA was observed in HF‐CsA animals, and may have played a role in the accelerated the development of heart failure at both the whole heart and cellular levels. Given the significant detriment to cardiac function observed in response to CsA, our findings suggest chronic CsA treatment is not a viable therapeutic option for HFpEF. PMID:24963034

  3. Myocardial infarction and intramyocardial injection models in swine

    PubMed Central

    McCall, Frederic C; Telukuntla, Kartik S; Karantalis, Vasileios; Suncion, Viky Y; Heldman, Alan W; Mushtaq, Muzammil; Williams, Adam R; Hare, Joshua M

    2014-01-01

    Sustainable and reproducible large animal models that closely replicate the clinical sequelae of myocardial infarction (MI) are important for the translation of basic science research into bedside medicine. Swine are well accepted by the scientific community for cardiovascular research, and they represent an established animal model for preclinical trials for US Food and Drug Administration (FDA) approval of novel therapies. Here we present a protocol for using porcine models of MI created with a closed-chest coronary artery occlusion-reperfusion technique. This creates a model of MI encompassing the anteroapical, lateral and septal walls of the left ventricle. This model infarction can be easily adapted to suit individual study design and enables the investigation of a variety of possible interventions. This model is therefore a useful tool for translational research into the pathophysiology of ventricular remodeling and is an ideal testing platform for novel biological approaches targeting regenerative medicine. This model can be created in approximately 8–10 h. PMID:22790084

  4. Model for heart failure education.

    PubMed

    Baldonado, Analiza; Dutra, Danette; Abriam-Yago, Katherine

    2014-01-01

    Heart failure (HF) is the heart's inability to meet the body's need for blood and oxygen. According to the American Heart Association 2013 update, approximately 5.1 million people are diagnosed with HF in the United States in 2006. Heart failure is the most common diagnosis for hospitalization. In the United States, the HF direct and indirect costs are estimated to be US $39.2 billion in 2010. To address this issue, nursing educators designed innovative teaching frameworks on HF management both in academia and in clinical settings. The model was based on 2 resources: the American Association of Heart Failure Nurses (2012) national nursing certification and the award-winning Pierce County Responsive Care Coordination Program. The HF educational program is divided into 4 modules. The initial modules offer foundational levels of Bloom's Taxonomy then progress to incorporate higher-levels of learning when modules 3 and 4 are reached. The applicability of the key components within each module allows formatting to enhance learning in all areas of nursing, from the emergency department to intensive care units to the medical-surgical step-down units. Also applicable would be to provide specific aspects of the modules to nurses who care for HF patients in skilled nursing facility, rehabilitation centers, and in the home-health care setting.

  5. A Bayesian network model for assessing natural estrogen fate and transport in a swine waste lagoon.

    PubMed

    Lee, Boknam; Kullman, Seth W; Yost, Erin; Meyer, Michael T; Worley-Davis, Lynn; Williams, C Michael; Reckhow, Kenneth H

    2014-10-01

    Commercial swine waste lagoons are regarded as a major reservoir of natural estrogens, which have the potential to produce adverse physiological effects on exposed aquatic organisms and wildlife. However, there remains limited understanding of the complex mechanisms of physical, chemical, and biological processes that govern the fate and transport of natural estrogens within an anaerobic swine lagoon. To improve lagoon management and ultimately help control the offsite transport of these compounds from swine operations, a probabilistic Bayesian network model was developed to assess natural estrogen fate and budget and then compared against data collected from a commercial swine field site. In general, the model was able to describe the estrogen fate and budget in both the slurry and sludge stores within the swine lagoon. Sensitivity analysis within the model demonstrated that the estrogen input loading from the associated barn facility was the most important factor in controlling estrogen concentrations within the lagoon slurry storage, whereas the settling rate was the most significant factor in the lagoon sludge storage. The degradation reactions were shown to be minor in both stores based on prediction of average total estrogen concentrations. Management scenario evaluations demonstrated that the best possible management options to reduce estrogen levels in the lagoon are either to adjust the estrogen input loading from swine barn facilities or to effectively enhance estrogen bonding with suspended solids through the use of organic polymers or inorganic coagulants.

  6. Magnetic Resonance Imaging of Heart Failure Using a Swine Model

    DTIC Science & Technology

    2011-03-21

    COPYRIGHT AND DISCLAIMER The author hereby certifies that the use of any copyrighted materials in the thesis manuscript entitled: "Magnetic...requestor warrants that the material shall not be used in any manner which may be considered derogatory to the title, content, or authors of the material , or...The requestor agrees to secure written permission from the author (for book material only). 7. Permission is valid if the borrowed material is

  7. Cardiac I-1c overexpression with reengineered AAV improves cardiac function in swine ischemic heart failure.

    PubMed

    Ishikawa, Kiyotake; Fish, Kenneth M; Tilemann, Lisa; Rapti, Kleopatra; Aguero, Jaume; Santos-Gallego, Carlos G; Lee, Ahyoung; Karakikes, Ioannis; Xie, Chaoqin; Akar, Fadi G; Shimada, Yuichi J; Gwathmey, Judith K; Asokan, Aravind; McPhee, Scott; Samulski, Jade; Samulski, Richard Jude; Sigg, Daniel C; Weber, Thomas; Kranias, Evangelia G; Hajjar, Roger J

    2014-12-01

    Cardiac gene therapy has emerged as a promising option to treat advanced heart failure (HF). Advances in molecular biology and gene targeting approaches are offering further novel options for genetic manipulation of the cardiovascular system. The aim of this study was to improve cardiac function in chronic HF by overexpressing constitutively active inhibitor-1 (I-1c) using a novel cardiotropic vector generated by capsid reengineering of adeno-associated virus (BNP116). One month after a large anterior myocardial infarction, 20 Yorkshire pigs randomly received intracoronary injection of either high-dose BNP116.I-1c (1.0 × 10(13) vector genomes (vg), n = 7), low-dose BNP116.I-1c (3.0 × 10(12) vg, n = 7), or saline (n = 6). Compared to baseline, mean left ventricular ejection fraction increased by 5.7% in the high-dose group, and by 5.2% in the low-dose group, whereas it decreased by 7% in the saline group. Additionally, preload-recruitable stroke work obtained from pressure-volume analysis demonstrated significantly higher cardiac performance in the high-dose group. Likewise, other hemodynamic parameters, including stroke volume and contractility index indicated improved cardiac function after the I-1c gene transfer. Furthermore, BNP116 showed a favorable gene expression pattern for targeting the heart. In summary, I-1c overexpression using BNP116 improves cardiac function in a clinically relevant model of ischemic HF.

  8. A simplified model for assessing the impact to groundwater of swine farms at regional level

    NASA Astrophysics Data System (ADS)

    Massabo, Marco; Viterbo, Angelo

    2013-04-01

    Swine manure can be an excellent source of nutrients for crop production. Several swine farms are present in the territory of Regione Umbria and more than 200.000 of swine heads are present yearly in the whole territory while some municipalities host more than 30.000 heads over a relatively limited land. Municipality with elevated number of swine heads has registered particularly higher Nitrate concentration in groundwater that requires a management plan and intervention in order to determine the maximum allowed N loads in the specific region. Use of manure and fertilizers in agricultural field produce diffuse nitrogen (N) losses that are a major cause of excessive nitrate concentrations in ground and surface waters and have been of concern since decades. Excessive nitrate concentrations in groundwater can have toxic effects when used as drinking water and cause eutrophication in surface waters. For management and environmental planning purposes, it is necessary to assess the magnitude of diffuse N losses from agricultural fields and how they are influenced by factors such as management practices, type of fertilizers -organic or inorganic - climate and soil etc. There are several methods for assessing N leaching, they span from methods based on field test to complex models that require many input data. We use a simple index method that accounts for the type of fertilizer used - inorganic, swine or cattle manure- and hydrological and hydrogeological conditions. Hydrological conditions such as infiltration rates are estimated by a fully distributed hydrological model. Data on inorganic and organic fertilization are estimated at municipal level by using the nutrient crops needs and the statistics of swine and cattle heads within the municipality. The index method has been calibrated by using groundwater concentration as a proxy of N losses from agriculture. A time series of three years of data has been analyzed. The application of the simple index method allowed to

  9. Anisotropic Failure Modeling for HY-100 Steel

    NASA Astrophysics Data System (ADS)

    Harstad, E. N.; Maudlin, P. J.; McKirgan, J. B.

    2004-07-01

    HY-100 steel is a material that behaves isotropically in the elastic and plastic region and acts anisotropically in failure. Since HY-100 is a ductile metal, a more gradual failure process is observed as opposed to the nearly instantaneous failure in brittle materials. We extend our elasto-plastic-damage constitutive model by including of a decohesion model to describe material behavior between the onset of failure and fracture. We also develop an anisotropic failure surface to account for directionality in material failure. Both the anisotropic failure and decohesion models have been implemented into a finite element code, where the effects of these models are studied in a uniaxial stress simulations, a plate impact simulations, and a quasistatic notched round bar tensile test simulations.

  10. Pathogenicity of swine influenza viruses possessing an avian or swine-origin PB2 polymerase gene evaluated in mouse and pig models

    PubMed Central

    Ma, Wenjun; Lager, Kelly M.; Li, Xi; Janke, Bruce H.; Mosier, Derek A; Painter, Laura E.; Ulery, Eva S.; Ma, Jingqun; Lekcharoensuk, Porntippa; Webby, Richard J.; Richt, Jürgen A.

    2010-01-01

    PB2 627K is a determinant of influenza host range and contributes to the pathogenicity of human-, avian-, and mouse-adapted influenza viruses in the mouse model. Here we used mouse and pig models to analyze the contribution of a swine-origin and avian-origin PB2 carrying either 627K or 627E in the background of the classical swine H1N1 (A/Swine/Iowa/15/30; 1930) virus. The results showed PB2 627K is crucial for virulence in the mouse model, independent of whether PB2 is derived from an avian or swine influenza virus (SIV). In the pig model, PB2 627E decreases pathogenicity of the classical 1930 SIV when it contains the swine-origin PB2, but not when it possesses the avian-origin PB2. Our study suggests the pathogenicity of SIVs with different PB2 genes and mutation of codon 627 in mice does not correlate with the pathogenicity of the same SIVs in the natural host, the pig. PMID:21074235

  11. Swine (Sus scrofa) as a Model of Postinfarction Mitral Regurgitation and Techniques to Accommodate Its Effects during Surgical Repair

    PubMed Central

    Sarin, Eric L; Shi, Weiwei; Duara, Rajnish; Melone, Todd A; Kalra, Kanika; Strong, Ashley; Girish, Apoorva; McIver, Bryant V; Thourani, Vinod H; Guyton, Robert A; Padala, Muralidhar

    2016-01-01

    Mitral regurgitation (MR) is a common heart-valve lesion after myocardial infarction in humans. Because it is considered a risk factor for accelerated heart failure and death, various surgical approaches and catheter-based devices to correct it are in development. Lack of a reproducible animal model of MR after myocardial infarction and reliable techniques to perform open-heart surgery in these diseased models led to the use of healthy animals to test new devices. Thus, most devices that are deemed safe in healthy animals have shown poor results in human efficacy studies, hampering progress in this area of research. Here we report our experience with a swine model of postinfarction MR, describe techniques to induce regurgitation and perform open-heart surgery in these diseased animals, and discuss our outcomes, complications, and solutions. PMID:27538860

  12. Swine (Sus scrofa) as a Model of Postinfarction Mitral Regurgitation and Techniques to Accommodate Its Effects during Surgical Repair.

    PubMed

    Sarin, Eric L; Shi, Weiwei; Duara, Rajnish; Melone, Todd A; Kalra, Kanika; Strong, Ashley; Girish, Apoorva; McIver, Bryant V; Thourani, Vinod H; Guyton, Robert A; Padala, Muralidhar

    2016-01-01

    Mitral regurgitation (MR) is a common heart-valve lesion after myocardial infarction in humans. Because it is considered a risk factor for accelerated heart failure and death, various surgical approaches and catheter-based devices to correct it are in development. Lack of a reproducible animal model of MR after myocardial infarction and reliable techniques to perform open-heart surgery in these diseased models led to the use of healthy animals to test new devices. Thus, most devices that are deemed safe in healthy animals have shown poor results in human efficacy studies, hampering progress in this area of research. Here we report our experience with a swine model of postinfarction MR, describe techniques to induce regurgitation and perform open-heart surgery in these diseased animals, and discuss our outcomes, complications, and solutions.

  13. ASPH modeling of Material Damage and Failure

    SciTech Connect

    Owen, J M

    2010-04-30

    We describe our new methodology for Adaptive Smoothed Particle Hydrodynamics (ASPH) and its application to problems in modeling material failure. We find that ASPH is often crucial for properly modeling such experiments, since in most cases the strain placed on materials is non-isotropic (such as a stretching rod), and without the directional adaptability of ASPH numerical failure due to SPH nodes losing contact in the straining direction can compete with or exceed the physical process of failure.

  14. Modelling the failure behaviour of wind turbines

    NASA Astrophysics Data System (ADS)

    Faulstich, S.; Berkhout, V.; Mayer, J.; Siebenlist, D.

    2016-09-01

    Modelling the failure behaviour of wind turbines is an essential part of offshore wind farm simulation software as it leads to optimized decision making when specifying the necessary resources for the operation and maintenance of wind farms. In order to optimize O&M strategies, a thorough understanding of a wind turbine's failure behaviour is vital and is therefore being developed at Fraunhofer IWES. Within this article, first the failure models of existing offshore O&M tools are presented to show the state of the art and strengths and weaknesses of the respective models are briefly discussed. Then a conceptual framework for modelling different failure mechanisms of wind turbines is being presented. This framework takes into account the different wind turbine subsystems and structures as well as the failure modes of a component by applying several influencing factors representing wear and break failure mechanisms. A failure function is being set up for the rotor blade as exemplary component and simulation results have been compared to a constant failure rate and to empirical wind turbine fleet data as a reference. The comparison and the breakdown of specific failure categories demonstrate the overall plausibility of the model.

  15. Common Cause Failure Modeling: Aerospace Versus Nuclear

    NASA Technical Reports Server (NTRS)

    Stott, James E.; Britton, Paul; Ring, Robert W.; Hark, Frank; Hatfield, G. Spencer

    2010-01-01

    Aggregate nuclear plant failure data is used to produce generic common-cause factors that are specifically for use in the common-cause failure models of NUREG/CR-5485. Furthermore, the models presented in NUREG/CR-5485 are specifically designed to incorporate two significantly distinct assumptions about the methods of surveillance testing from whence this aggregate failure data came. What are the implications of using these NUREG generic factors to model the common-cause failures of aerospace systems? Herein, the implications of using the NUREG generic factors in the modeling of aerospace systems are investigated in detail and strong recommendations for modeling the common-cause failures of aerospace systems are given.

  16. Swine origin influenza (swine flu).

    PubMed

    Sebastian, Meghna R; Lodha, Rakesh; Kabra, S K

    2009-08-01

    Swine origin influenza was first recognized in the border area of Mexico and United States in April 2009 and during a short span of two months became the first pandemic. The currently circulating strain of swine origin influenza virus of the H1N1 strain has undergone triple reassortment and contains genes from the avian, swine and human viruses. It is transmitted by droplets or fomites. Incubation period is 2 to 7 days. Common clinical symptoms are indistinguishable by any viral respiratory illness, and include fever, cough, sore throat and myalgia. A feature seen more frequently with swine origin influenza is GI upset. Less than 10% of patients require hospitalization. Patients at risk of developing severe disease are - younger than five years, elderly, pregnant women, with chronic systemic illnesses, adolescents on aspirin. Of the severe manifestations of swine origin influenza, pneumonia and respiratory failure are the most common. Unusual symptoms reported are conjunctivitis, parotitis, hemophagocytic syndrome. Infants may present with fever and lethargy with no respiratory symptoms. Diagnosis is based on RT PCR, Viral culture or increasing neutralizing antibodies. Principle of treatment consist of isolation, universal precautions, good infection control practices, supportive care and use of antiviral drugs. Antiviral drugs effective against H1N1 virus include: oseltamivir and zamanavir. With good supportive care case fatality is less than 1%. Preventive measures include: social distancing, practicing respiratory etiquette, hand hygiene and use of chemoprohylaxis with antiviral drugs. Vaccine against H1N1 is not available at present, but will be available in near future.

  17. Model degradation effects on sensor failure detection

    NASA Technical Reports Server (NTRS)

    Leininger, G. G.

    1981-01-01

    This paper discusses the effects of imperfect modeling on the detection and isolation of sensor failures. For systems with non-zero set points, deterministic inputs or non-zero noise biases, the model mismatch appears as a bias on the stochastic innovation process. This bias, if left unaccounted for, would be sufficient to declare a false alarm failure in one or more sensors. A practical design procedure based upon the Generalized Likelihood Ratio (GLR) form uses a finite data window sequential t-test to detect and isolate model mismatch effects and soft sensor failures. Application to an eighth order model of the QCSEE turbofan engine is discussed.

  18. Dynamic Constitutive/Failure Models

    DTIC Science & Technology

    1988-12-01

    compressive failure--microfracture versus microplasticity . Actual traces observed in plate impact tests on ceramic targets are hardly ever as simple as the...observa- tions for microfracture and microplasticity . Unfortunately, each team of investigators has used slightly different experimental techniques and

  19. One-Health Simulation Modelling: A Case Study of Influenza Spread between Human and Swine Populations using NAADSM.

    PubMed

    Dorjee, S; Revie, C W; Poljak, Z; McNab, W B; Sanchez, J

    2016-02-01

    The circulation of zoonotic influenza A viruses including pH1N1 2009 and H5N1 continue to present a constant threat to animal and human populations. Recently, an H3N2 variant spread from pigs to humans and between humans in limited numbers. Accordingly, this research investigated a range of scenarios of the transmission dynamics of pH1N1 2009 virus at the swine-human interface while accounting for different percentages of swine workers initially immune. Furthermore, the feasibility of using NAADSM (North American Animal Disease Spread Model) applied as a one-health simulation model was assessed. The study population included 488 swine herds and 29, 707 households of people within a county in Ontario, Canada. Households were categorized as follows: (i) rural households with swine workers, (ii) rural households without swine workers, and (iii) urban households without swine workers. Forty-eight scenarios were investigated, based on the combination of six scenarios around the transmissibility of the virus at the interface and four vaccination coverage levels of swine workers (0-60%), all under two settings of either swine or human origin of the virus. Outcomes were assessed in terms of stochastic 'die-out' fraction, size and time to peak epidemic day, overall size and duration of the outbreaks. The modelled outcomes indicated that minimizing influenza transmissibility at the interface and targeted vaccination of swine workers had significant beneficial effects. Our results indicate that NAADSM can be used as a framework to model the spread and control of contagious zoonotic diseases among animal and human populations, under certain simplifying assumptions. Further evaluation of the model is required. In addition to these specific findings, this study serves as a benchmark that can provide useful input to a future one-health influenza modelling studies. Some pertinent information gaps were also identified. Enhanced surveillance and the collection of high

  20. Animal models of acute renal failure.

    PubMed

    Singh, Amrit Pal; Junemann, Anselm; Muthuraman, Arunachalam; Jaggi, Amteshwar Singh; Singh, Nirmal; Grover, Kuldeep; Dhawan, Ravi

    2012-01-01

    The animal models are pivotal for understanding the characteristics of acute renal failure (ARF) and development of effective therapy for its optimal management. Since the etiology for induction of renal failure is multifold, therefore, a large number of animal models have been developed to mimic the clinical conditions of renal failure. Glycerol-induced renal failure closely mimics the rhabdomyolysis; ischemia-reperfusion-induced ARF simulate the hemodynamic changes-induced changes in renal functioning; drug-induced such as gentamicin, cisplatin, NSAID, ifosfamide-induced ARF mimics the renal failure due to clinical administration of respective drugs; uranium, potassium dichromate-induced ARF mimics the occupational hazard; S-(1,2-dichlorovinyl)-L-cysteine-induced ARF simulate contaminated water-induced renal dysfunction; sepsis-induced ARF mimics the infection-induced renal failure and radiocontrast-induced ARF mimics renal failure in patients during use of radiocontrast media at the time of cardiac catheterization. Since each animal model has been created with specific methodology, therefore, it is essential to describe the model in detail and consequently interpret the results in the context of a specific model.

  1. Endotracheal intubation in swine.

    PubMed

    Chum, Helen; Pacharinsak, Cholawat

    2012-11-01

    Swine are commonly used as research models for cardiovascular surgery and disease, gastrointestinal disease, organ transplantation and intra-renal surgery. These surgical models require anesthesia and, consequently, endotracheal intubation in order to protect the airway; prevent aspiration of saliva, blood and foreign materials; and maintain positive pressure ventilation of the animal. Successful intubation is vital to the stable maintenance of swine under inhalational anesthesia. Here we discuss key features of swine anatomy that make intubation challenging, equipment necessary for successful intubation and techniques for endotracheal intubation in swine.

  2. Using a chemical equilibrium model to predict amendments required to precipitate phosphorus as struvite in liquid swine manure.

    PubMed

    Celen, Ipek; Buchanan, John R; Burns, Robert T; Robinson, R Bruce; Raman, D Raj

    2007-04-01

    Precipitation of phosphate minerals from liquid swine manure is an established means of reducing the orthophosphate (OP) concentration. This project investigated the usefulness of a chemical equilibrium model, Visual Minteq, for prescribing the amendments needed to maximize struvite precipitation from liquid swine manure and thus reduce the OP phosphorus concentration. The actual concentrations of Mg(2+), Ca(2+), K(+), OP, NH(4)(+), alkalinity and pH from a liquid swine manure system were used as inputs to the model. The model was modified to remove species with extremely low formation rates, because they would not significantly precipitate in the reaction occurring in a short retention-time process such as those envisioned for swine manure struvite-formation reactors. Using the model's output, a series of 19-L reactors were used to verify the results. Verification results demonstrated that Visual Minteq can be used to pre-determine the concentration of amendments required to maximize struvite recovery.

  3. Pyruvate modifies metabolic flux and nutrient sensing during extracorporeal membrane oxygenation in an immature swine model

    PubMed Central

    Ledee, Dolena R.; Kajimoto, Masaki; O'Kelly Priddy, Colleen M.; Olson, Aaron K.; Isern, Nancy; Robillard-Frayne, Isabelle; Des Rosiers, Christine

    2015-01-01

    Extracorporeal membrane oxygenation (ECMO) provides mechanical circulatory support for infants and children with postoperative cardiopulmonary failure. Nutritional support is mandatory during ECMO although specific actions for substrates on the heart have not been delineated. Prior work shows that enhancing pyruvate oxidation promotes successful weaning from ECMO. Accordingly, we tested the hypothesis that prolonged systemic pyruvate supplementation activates pyruvate oxidation in an immature swine model in vivo. Twelve male mixed-breed Yorkshire piglets (age 30–49 days) received systemic infusion of either normal saline (group C) or pyruvate (group P) during the final 6 h of 8 h of ECMO. Over the final hour, piglets received [2-13C] pyruvate, as a reference substrate for oxidation, and [13C6]-l-leucine, as an indicator for amino acid oxidation and protein synthesis. A significant increase in lactate and pyruvate concentrations occurred, along with an increase in the absolute concentration of the citric acid cycle intermediates. An increase in anaplerotic flux through pyruvate carboxylation in group P occurred compared with no change in pyruvate oxidation. Additionally, pyruvate promoted an increase in the phosphorylation state of several nutrient-sensitive enzymes, like AMP-activated protein kinase and acetyl CoA carboxylase, suggesting activation for fatty acid oxidation. Pyruvate also promoted O-GlcNAcylation through the hexosamine biosynthetic pathway. In conclusion, although prolonged pyruvate supplementation did not alter pyruvate oxidation, it did elicit changes in nutrient- and energy-sensitive pathways. Therefore, the observed results support the further study of pyruvate and its downstream effect on cardiac function. PMID:25910802

  4. Myeloid Leukemias and Virally Induced Lymphomas in Miniature Inbred Swine: Development of a Large Animal Tumor Model.

    PubMed

    Duran-Struuck, Raimon; Matar, Abraham J; Huang, Christene A

    2015-01-01

    The lack of a large animal transplantable tumor model has limited the study of novel therapeutic strategies for the treatment of liquid cancers. Swine as a species provide a natural option based on their similarities with humans and their already extensive use in biomedical research. Specifically, the Massachusetts General Hospital miniature swine herd retains unique genetic characteristics that facilitate the study of hematopoietic cell and solid organ transplantation. Spontaneously arising liquid cancers in these swine, specifically myeloid leukemias and B cell lymphomas, closely resemble human malignancies. The ability to establish aggressive tumor cell lines in vitro from these naturally occurring malignancies makes a transplantable tumor model a close reality. Here, we discuss our experience with myeloid and lymphoid tumors in major histocompatibility characterized miniature swine and future approaches regarding the development of a large animal transplantable tumor model.

  5. Development of a Standard Swine Hemorrhage Model for Efficacy Assessment of Topical Hemostatic Agents

    DTIC Science & Technology

    2011-07-01

    1. Pictures of preparation of femora l artery injury model in swine: (A) femoral artery vessel was isolated and treated with lidocaine for optimum...Briefly, the femoral artery was isolated and treated with lidocaine for optimum dilation (Fig. I, A). The vascular injury (6-mm punched hole in...effective in any circumstance. Application of lidocaine to dilate the vessel is not clinically relevant; how- ever, it is a necessary step in this

  6. A surgical model for studying biliary bile acid and cholesterol metabolism in swine.

    PubMed

    Faidley, T D; Galloway, S T; Luhman, C M; Foley, M K; Beitz, D C

    1991-10-01

    Techniques were developed in young growing pigs to simultaneously collect and reinfuse bile. Silastic cannulae were designed and surgically implanted in the common bile duct and the duodenum. Direct sampling of the hepatic bile was achieved by bypassing the gallbladder. The techniques allowed for steady-state studies of hepatic function to be conducted in conscious swine in two different studies. Pigs, thus surgically modified, can serve as an appropriate model for physiologic, pharmacologic, and nutritional research that involves bile sampling.

  7. A Cellular Automaton Model of Catastrophic Failure

    NASA Astrophysics Data System (ADS)

    Serino, C. A.; Klein, W.

    2009-03-01

    We introduce a two-dimensional cellular automaton model for studying the catastrophic failure of materials under stress. Our model is similar to the Olami-Feder-Christensen earthquake model [Z. Olami et al., Phys. Rev. Lett. 68, 1244 (1992)] except that after a site fails f-times, it no longer can receive stress from its neighbors. In the limit that the interaction range, R, goes to infinity, our model is equivalent to the global load sharing fiber bundle model of Pierce [F. T.Pierce, J. Text. Ind. 17, 355 (1926)] and Daniels [H. E. Daniels, Proc. Roy. Soc. London A 183, 405 (1945)]. By varying the interaction range, we observe two qualitatively different failure modes. For R 1 catastrophic failure resembles a nucleation-like event which grows symmetrically from a single initiating site and fails every site in the lattice. In contrast, for R 1 a percolating cluster of failed sites spans the system despite the many active sites that persist, even after catastrophic failure. We use the stress-fluctuation metric to study the ergodicity of our model and hence the validity of equilibrium descriptions of fracture.

  8. Novel Threadlike Structures May Be Present on the Large Animal Organ Surface: Evidence in Swine Model

    PubMed Central

    Bae, Kyoung-Hee; Park, Sang Hyun; Lee, Byung-Cheon; Nam, Min-Ho; Yoon, Ji Woong; Kwon, Hee-Min; Yoon, Seung Zhoo

    2013-01-01

    Background. The types of embryonic development probably provoke different paths of novel threadlike structure (NTS) development. The authors hypothesized that NTS may be easily observed on the surface of swine intestines by using trypan blue staining method and visualization under an optical microscope. Methods. General anesthesia was administered to 2 Yorkshire pigs. The abdominal walls of the pigs were carefully dissected along the medial alba. NTSs were identified on organ surfaces under a stereoscopic microscope after trypan blue staining. Isolated NTS specimens obtained from the large intestine were subjected to 4′,6-diamidino-2-phenylindole (DAPI) staining and observed using the polarized light microscopy to confirm whether the obtained structure fits the definition of NTS. Results. We found elastic, semitransparent threadlike structures (forming a network structure) that had a milky-white color in situ and in vivo in swine large intestines. The samples showed distinct extinction of polarized light at every 90 degrees, and nucleus was shown to be rod shaped by DAPI staining, indicating that they meet the criteria of NTS. Conclusion. We used a swine model to demonstrate that NTS may be present on large animal organ surfaces. Our results may permit similar studies by using human specimens. PMID:23762159

  9. Novel threadlike structures may be present on the large animal organ surface: evidence in Swine model.

    PubMed

    Bae, Kyoung-Hee; Park, Sang Hyun; Lee, Byung-Cheon; Nam, Min-Ho; Yoon, Ji Woong; Kwon, Hee-Min; Yoon, Seung Zhoo

    2013-01-01

    Background. The types of embryonic development probably provoke different paths of novel threadlike structure (NTS) development. The authors hypothesized that NTS may be easily observed on the surface of swine intestines by using trypan blue staining method and visualization under an optical microscope. Methods. General anesthesia was administered to 2 Yorkshire pigs. The abdominal walls of the pigs were carefully dissected along the medial alba. NTSs were identified on organ surfaces under a stereoscopic microscope after trypan blue staining. Isolated NTS specimens obtained from the large intestine were subjected to 4',6-diamidino-2-phenylindole (DAPI) staining and observed using the polarized light microscopy to confirm whether the obtained structure fits the definition of NTS. Results. We found elastic, semitransparent threadlike structures (forming a network structure) that had a milky-white color in situ and in vivo in swine large intestines. The samples showed distinct extinction of polarized light at every 90 degrees, and nucleus was shown to be rod shaped by DAPI staining, indicating that they meet the criteria of NTS. Conclusion. We used a swine model to demonstrate that NTS may be present on large animal organ surfaces. Our results may permit similar studies by using human specimens.

  10. Association of the Host Immune Response with Protection Using a Live Attenuated African Swine Fever Virus Model

    PubMed Central

    Carlson, Jolene; O’Donnell, Vivian; Alfano, Marialexia; Velazquez Salinas, Lauro; Holinka, Lauren G.; Krug, Peter W.; Gladue, Douglas P.; Higgs, Stephen; Borca, Manuel V.

    2016-01-01

    African swine fever (ASF) is a lethal hemorrhagic disease of swine caused by a double-stranded DNA virus, ASF virus (ASFV). There is no vaccine to prevent the disease and current control measures are limited to culling and restricting animal movement. Swine infected with attenuated strains are protected against challenge with a homologous virulent virus, but there is limited knowledge of the host immune mechanisms generating that protection. Swine infected with Pretoriuskop/96/4 (Pret4) virus develop a fatal severe disease, while a derivative strain lacking virulence-associated gene 9GL (Pret4Δ9GL virus) is completely attenuated. Swine infected with Pret4Δ9GL virus and challenged with the virulent parental virus at 7, 10, 14, 21, and 28 days post infection (dpi) showed a progressive acquisition of protection (from 40% at 7 dpi to 80% at 21 and 28 dpi). This animal model was used to associate the presence of host immune response (ASFV-specific antibody and interferon (IFN)-γ responses, or specific cytokine profiles) and protection against challenge. With the exception of ASFV-specific antibodies in survivors challenged at 21 and 28 dpi, no association between the parameters assessed and protection could be established. These results, encompassing data from 65 immunized swine, underscore the complexity of the system under study, suggesting that protection relies on the concurrence of different host immune mechanisms. PMID:27782090

  11. Failure diagnosis using discrete event models

    SciTech Connect

    Sampath, M.; Sengupta, R.; Lafortune, S.; Teneketzis, D.; Sinnamohideen, K.

    1994-12-31

    We propose a Discrete Event Systems (DES) approach to the failure diagnosis problem. We present a methodology for modeling physical systems in a DES framework. We discuss the notion of diagnosability and present the construction procedure of the diagnoser. Finally, we illustrate our approach using a Heating, Ventilation and Air Conditioning (HVAC) system.

  12. Modeling of microstructural effects on electromigration failure

    SciTech Connect

    Ceric, H.; Orio, R. L. de; Zisser, W.; Selberherr, S.

    2014-06-19

    Current electromigration models used for simulation and analysis of interconnect reliability lack the appropriate description of metal microstructure and consequently have a very limited predictive capability. Therefore, the main objective of our work was obtaining more sophisticated electromigration tools. The problem is addressed through a combination of different levels of atomistic modeling and already available, continuum level macroscopic models. A novel method for an ab initio calculation of the effective valence for electromigration is presented and its application on the analysis of EM behavior is demonstrated. Additionally, a simple analytical model for the early electromigration lifetime is obtained. We have shown that its application provides a reasonable estimate for the early electromigration failures including the effect of microstructure. A simulation study is also applied on electromigration failure in tin solder bumps, where it contributed the understanding of the role of tin crystal anisotropy in the degradation mechanism of solder bumps.

  13. Scenario tree model for animal disease freedom framed in the OIE context using the example of a generic swine model for Aujeszky's disease in commercial swine in Canada.

    PubMed

    Christensen, Jette; Vallières, André

    2016-01-01

    "Freedom from animal disease" is an ambiguous concept that may have a different meaning in trade and science. For trade alone, there are different levels of freedom from OIE listed diseases. A country can: be recognized by OIE to be "officially free"; self-declare freedom, with no official recognition by the OIE; or report animal disease as absent (no occurrence) in six-monthly reports. In science, we apply scenario tree models to calculate the probability of a population being free from disease at a given prevalence to provide evidence of freedom from animal disease. Here, we link science with application by describing how a scenario tree model may contribute to a country's claim of freedom from animal disease. We combine the idea of a standardized presentation of scenario tree models for disease freedom and having a similar model for two different animal diseases to suggest that a simple generic model may help veterinary authorities to build and evaluate scenario tree models for disease freedom. Here, we aim to develop a generic scenario tree model for disease freedom that is: animal species specific, population specific, and has a simple structure. The specific objectives were: to explore the levels of freedom described in the OIE Terrestrial Animal Health Code; to describe how scenario tree models may contribute to a country's claim of freedom from animal disease; and to present a generic swine scenario tree model for disease freedom in Canada's domestic (commercial) swine applied to Aujeszky's disease (AD). In particular, to explore how historical survey data, and data mining may affect the probability of freedom and to explore different sampling strategies. Finally, to frame the generic scenario tree model in the context of Canada's claim of freedom from AD. We found that scenario tree models are useful to support a country's claim of freedom either as "recognized officially free" or as part of a self-declaration but the models should not stand alone in a

  14. Interspecies Mixed-Effect Pharmacokinetic Modeling of Penicillin G in Cattle and Swine

    PubMed Central

    Li, Mengjie; Gehring, Ronette; Tell, Lisa; Baynes, Ronald; Huang, Qingbiao

    2014-01-01

    Extralabel drug use of penicillin G in food-producing animals may cause an excess of residues in tissue which will have the potential to damage human health. Of all the antibiotics, penicillin G may have the greatest potential for producing allergic responses to the consumer of food animal products. There are, however, no population pharmacokinetic studies of penicillin G for food animals. The objective of this study was to develop a population pharmacokinetic model to describe the time-concentration data profile of penicillin G across two species. Data were collected from previously published pharmacokinetic studies in which several formulations of penicillin G were administered to diverse populations of cattle and swine. Liver, kidney, and muscle residue data were also used in this study. Compartmental models with first-order absorption and elimination were fit to plasma and tissue concentrations using a nonlinear mixed-effect modeling approach. A 3-compartment model with extra tissue compartments was selected to describe the pharmacokinetics of penicillin G. Typical population parameter estimates (interindividual variability) were central volumes of distribution of 3.45 liters (12%) and 3.05 liters (8.8%) and central clearance of 105 liters/h (32%) and 16.9 liters/h (14%) for cattle and swine, respectively, with peripheral clearance of 24.8 liters/h (13%) and 9.65 liters/h (23%) for cattle and 13.7 liters/h (85%) and 0.52 liters/h (40%) for swine. Body weight and age were the covariates in the final pharmacokinetic models. This study established a robust model of penicillin for a large and diverse population of food-producing animals which could be applied to other antibiotics and species in future analyses. PMID:24867969

  15. Interspecies mixed-effect pharmacokinetic modeling of penicillin G in cattle and swine.

    PubMed

    Li, Mengjie; Gehring, Ronette; Tell, Lisa; Baynes, Ronald; Huang, Qingbiao; Riviere, Jim E

    2014-08-01

    Extralabel drug use of penicillin G in food-producing animals may cause an excess of residues in tissue which will have the potential to damage human health. Of all the antibiotics, penicillin G may have the greatest potential for producing allergic responses to the consumer of food animal products. There are, however, no population pharmacokinetic studies of penicillin G for food animals. The objective of this study was to develop a population pharmacokinetic model to describe the time-concentration data profile of penicillin G across two species. Data were collected from previously published pharmacokinetic studies in which several formulations of penicillin G were administered to diverse populations of cattle and swine. Liver, kidney, and muscle residue data were also used in this study. Compartmental models with first-order absorption and elimination were fit to plasma and tissue concentrations using a nonlinear mixed-effect modeling approach. A 3-compartment model with extra tissue compartments was selected to describe the pharmacokinetics of penicillin G. Typical population parameter estimates (interindividual variability) were central volumes of distribution of 3.45 liters (12%) and 3.05 liters (8.8%) and central clearance of 105 liters/h (32%) and 16.9 liters/h (14%) for cattle and swine, respectively, with peripheral clearance of 24.8 liters/h (13%) and 9.65 liters/h (23%) for cattle and 13.7 liters/h (85%) and 0.52 liters/h (40%) for swine. Body weight and age were the covariates in the final pharmacokinetic models. This study established a robust model of penicillin for a large and diverse population of food-producing animals which could be applied to other antibiotics and species in future analyses.

  16. Laparoscopic inguinal herniorrhaphy in a swine model. Third place winner of the Conrad Jobst Award in the Gold Medal paper competition.

    PubMed

    Layman, T S; Burns, R P; Chandler, K E; Russell, W L; Cook, R G

    1993-01-01

    A simplified method of laparoscopic inguinal herniorrhaphy using prosthetic materials was evaluated in a swine hernia model. The goals of this study were to determine 1) effectiveness of repair in a rapidly growing animal, 2) effectiveness and extent of adhesion formation of different prosthetic materials, 3) the effect of repair on testicular growth, and 4) histologic effects on the hernia site and surrounding structures. In a prospective randomized study, 30 juvenile male swine (average, 23 kg) with 35 congenital indirect inguinal hernias underwent laparoscopic herniorrhaphy using one of three prosthetic materials: Group 1 (polytetrafluoroethylene/Gore-Tex), N = 10; Group 2 (polypropylene mesh/Marlex), N = 10; Group 3 (polypropylene mesh/Prolene), N = 10. A standardized laparoscopic herniorrhaphy technique consisting of stapling prosthetic material over the hernia defect without peritoneal dissection was employed. During the 3-month postoperative period, animals were sequentially examined for normal growth and development, normal testicular development, and signs of hernia recurrence. Clinically apparent complications related to herniorrhaphy occurred in five animals (17%) during the observation period (one with repair failure, one with testicular torsion, two with repair failure and bowel obstruction, and one with intestinal obstruction secondary to adhesions). All three animals with bowel obstruction died. At 90 days after surgery all remaining animals (N = 27) were euthanized (Group 1 = 9, Group 2 = 8, Group 3 = 10). Average weight was 84 kg. Necropsy findings included no additional hernia recurrences, and one mesh erosion into the urinary bladder.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Rotating Frame Spin Lattice Relaxation in a Swine Model of Chronic, Left Ventricular Myocardial Infarction

    PubMed Central

    Witschey, Walter RT; Pilla, James J; Ferrari, Giovanni; Koomalsingh, Kevin; Haris, Mohammed; Hinmon, Robin; Zsido, Gerald; Gorman, Joseph H; Gorman, Robert C; Reddy, Ravinder

    2010-01-01

    T1ρ relaxation times were quantified in a swine model of chronic, left ventricular myocardial infarction. It was found that there were low frequency relaxation mechanisms that suppress endogenous contrast at low spin lock amplitudes and in T2-weighted images. A moderate amplitude spin locking pulse could overcome these relaxation mechanisms. Relaxation dispersion data was measured over a range of RF field amplitudes and a model was formulated to include dipole-dipole relaxation modulated by molecular rotation and an apparent exchange mechanism. These techniques may find some use in the clinic for the observation of chronic, left ventricular cardiac remodeling. PMID:20677236

  18. Characterization of right ventricular remodeling and failure in a chronic pulmonary hypertension model

    PubMed Central

    Ishikawa, Kiyotake; Hadri, Lahouaria; Santos-Gallego, Carlos; Fish, Kenneth; Hammoudi, Nadjib; Chaanine, Antoine; Torquato, Samantha; Naim, Charbel; Ibanez, Borja; Pereda, Daniel; García-Alvarez, Ana; Fuster, Valentin; Sengupta, Partho P.; Leopold, Jane A.; Hajjar, Roger J.

    2014-01-01

    In pulmonary hypertension (PH), right ventricular (RV) dysfunction and failure is the main determinant of a poor prognosis. We aimed to characterize RV structural and functional differences during adaptive RV remodeling and progression to RV failure in a large animal model of chronic PH. Postcapillary PH was created surgically in swine (n = 21). After an 8- to 14-wk follow-up, two groups were identified based on the development of overt heart failure (HF): PH-NF (nonfailing, n = 12) and PH-HF (n = 8). In both groups, invasive hemodynamics, pressure-volume relationships, and echocardiography confirmed a significant increase in pulmonary pressures and vascular resistance consistent with PH. Histological analysis also demonstrated distal pulmonary arterial (PA) remodeling in both groups. Diastolic dysfunction, defined by a steeper RV end-diastolic pressure-volume relationship and longitudinal strain, was found in the absence of HF as an early marker of RV remodeling. RV contractility was increased in both groups, and RV-PA coupling was preserved in PH-NF animals but impaired in the PH-HF group. RV hypertrophy was present in PH-HF, although there was evidence of increased RV fibrosis in both PH groups. In the PH-HF group, RV sarcoplasmic reticulum Ca2+-ATPase2a expression was decreased, and endoplasmic reticulum stress was increased. Aldosterone levels were also elevated in PH-HF. Thus, in the swine pulmonary vein banding model of chronic postcapillary PH, RV remodeling occurs at the structural, histological, and molecular level. Diastolic dysfunction and fibrosis are present in adaptive RV remodeling, whereas the onset of RV failure is associated with RV-PA uncoupling, defective calcium handling, and hyperaldosteronism. PMID:25158063

  19. Inactivation of Viruses and Bacteriophages as Models for Swine Hepatitis E Virus in Food Matrices.

    PubMed

    Emmoth, Eva; Rovira, Jordi; Rajkovic, Andreja; Corcuera, Elena; Wilches Pérez, Diego; Dergel, Irene; Ottoson, Jakob R; Widén, Frederik

    2017-03-01

    Hepatitis E virus has been recognised as a food-borne virus hazard in pork products, due to its zoonotic properties. This risk can be reduced by adequate treatment of the food to inactivate food-borne viruses. We used a spectrum of viruses and bacteriophages to evaluate the effect of three food treatments: high pressure processing (HPP), lactic acid (LA) and intense light pulse (ILP) treatments. On swine liver at 400 MPa for 10 min, HPP gave log10 reductions of ≥4.2, ≥5.0 and 3.4 for feline calicivirus (FCV) 2280, FCV wildtype (wt) and murine norovirus 1 (MNV 1), respectively. Escherichia coli coliphage ϕX174 displayed a lower reduction of 1.1, while Escherichia coli coliphage MS2 was unaffected. For ham at 600 MPa, the corresponding reductions were 4.1, 4.4, 2.9, 1.7 and 1.3 log10. LA treatment at 2.2 M gave log10 reductions in the viral spectrum of 0.29-2.1 for swine liver and 0.87-3.1 for ham, with ϕX174 and MNV 1, respectively, as the most stable microorganisms. The ILP treatment gave log10 reductions of 1.6-2.8 for swine liver, 0.97-2.2 for ham and 1.3-2.3 for sausage, at 15-60 J cm(-2), with MS2 as the most stable microorganism. The HPP treatment gave significantly (p < 0.05) greater virus reduction on swine liver than ham for the viruses at equivalent pressure/time combinations. For ILP treatment, reductions on swine liver were significantly (p < 0.05) greater than on ham for all microorganisms. The results presented here could be used in assessments of different strategies to protect consumers against virus contamination and in advice to food producers. Conservative model indicators for the pathogenic viruses could be suggested.

  20. Modeling the biomechanics of swine mastication--an inverse dynamics approach.

    PubMed

    Basafa, Ehsan; Murphy, Ryan J; Gordon, Chad R; Armand, Mehran

    2014-08-22

    A novel reconstructive alternative for patients with severe facial structural deformity is Le Fort-based, face-jaw-teeth transplantation (FJTT). To date, however, only ten surgeries have included underlying skeletal and jaw-teeth components, all yielding sub-optimal results and a need for a subsequent revision surgery, due to size mismatch and lack of precise planning. Numerous studies have proven swine to be appropriate candidates for translational studies including pre-operative planning of transplantation. An important aspect of planning FJTT is determining the optimal muscle attachment sites on the recipient's jaw, which requires a clear understanding of mastication and bite mechanics in relation to the new donated upper and/or lower jaw. A segmented CT scan coupled with data taken from literature defined a biomechanical model of mandible and jaw muscles of a swine. The model was driven using tracked motion and external force data of one cycle of chewing published earlier, and predicted the muscle activation patterns as well as temporomandibular joint (TMJ) reaction forces and condylar motions. Two methods, polynomial and min/max optimization, were used for solving the muscle recruitment problem. Similar performances were observed between the two methods. On average, there was a mean absolute error (MAE) of <0.08 between the predicted and measured activation levels of all muscles, and an MAE of <7 N for TMJ reaction forces. Simulated activations qualitatively followed the same patterns as the reference data and there was very good agreement for simulated TMJ forces. The polynomial optimization produced a smoother output, suggesting that it is more suitable for studying such motions. Average MAE for condylar motion was 1.2mm, which reduced to 0.37 mm when the input incisor motion was scaled to reflect the possible size mismatch between the current and original swine models. Results support the hypothesis that the model can be used for planning of facial

  1. Modelling the failure modes in geobag revetments.

    PubMed

    Akter, A; Crapper, M; Pender, G; Wright, G; Wong, W S

    2012-01-01

    In recent years, sand filled geotextile bags (geobags) have been used as a means of long-term riverbank revetment stabilization. However, despite their deployment in a significant number of locations, the failure modes of such structures are not well understood. Three interactions influence the geobag performance, i.e. geobag-geobag, geobag-water flow and geobag-water flow-river bank. The aim of the research reported here is to develop a detailed understanding of the failure mechanisms in a geobag revetment using a discrete element model (DEM) validated by laboratory data. The laboratory measured velocity data were used for preparing a mapped velocity field for a coupled DEM simulation of geobag revetment failure. The validated DEM model could identify well the critical bag location in varying water depths. Toe scour, one of the major instability factors in revetments, and its influence on the bottom-most layer of the bags were also reasonably represented in this DEM model. It is envisaged that the use of a DEM model will provide more details on geobag revetment performance in riverbanks.

  2. Detection and evaluation of renal biomarkers in a swine model of acute myocardial infarction and reperfusion.

    PubMed

    Duan, Su-Yan; Xing, Chang-Ying; Zhang, Bo; Chen, Yan

    2015-01-01

    The prevalence of type 1 cardiorenal syndrome (CRS) is increasing and strongly associated with long-term mortality. However, lack of reliable animal models and well-defined measures of renoprotection, made early diagnosis and therapy difficult. We previously successfully established the swine acute myocardial infarction (AMI) model of ischemia-reperfusion by blocking left anterior descending branch (LAD). Reperfusion was performed after 90-minute occlusion of the LAD. AMI was confirmed by ECG and left ventricular angiography (LVG). Then those 52 survived AMI reperfusion swine, including ventricular fibrillation-cardiac arrest after restoration of blood flow, were randomly divided into four groups (four/group) according to different interventions: resuscitation in room temperature, resuscitation with 500 ml saline in room temperature, resuscitation with 4°C 500 ml saline and normal control (with no intervention of resuscitation). Each group was further observed in four groups according to different time of resuscitation after ventricular arrhythmias: 1, 3, 5, 10-minute reperfusion after ventricular arrhythmias. Plasma and random urine were collected to evaluate renal function and test renal biomarkers of acute kidney injury (AKI). Our swine AMI model of ischemia-reperfusion provoked subclinical AKI with the elevation of the tubular damage biomarker, NGAL, IL-18 and L-FABP. Renal damage rapidly observed after hemodynamic instability, rather than observation after several hours as previously reported. The increasing rate of biological markers declined after interventions, however, its impact on the long-term prognosis remains to be further studied. These data show that elevation of tubular damage biomarkers without glomerular function loss may indicate appropriate timing for effective renoprotections like hypothermia resuscitation in type 1 CRS.

  3. Stochastic Models for Common Failures of Components.

    DTIC Science & Technology

    1984-03-01

    common cause model, NUREG /CR-1401, 1980. [3] Church, J. D. and Harris, B., The estimation of reliability from stress- strength relationship...Fachband 2/1, 1980. [11] Lewis, H. W., Chairman, Risk Assessment Review Group Report to the U. S. Nuclear Regulatory Commission, NUREG /CR-0400, 1978. [12...Regulatory Commission, P.R.A. Procedures Guide, NUREG / CR-2300, 1983. [18] Vesely, W. E., Estimating Common Cause Failure Probabilities in Reliability and

  4. Ischemic Effects of Transcatheter Arterial Embolization with N-Butyl Cyanoacrylate-Lipiodol on the Colon in a Swine Model

    SciTech Connect

    Ikoma, Akira; Kawai, Nobuyuki; Sato, Morio Sonomura, Tetsuo; Minamiguchi, Hiroki; Nakai, Motoki; Takasaka, Isao; Nakata, Kouhei; Sahara, Shinya; Sawa, Naohisa; Shirai, Shintaro; Mori, Ichiro

    2010-10-15

    This study was designed to assess the safety of transcatheter arterial embolization (TAE) with n-butyl cyanoacrylate-lipiodol (NBCA-Lp) for the large bowel and to investigate the vital response to NBCA-Lp in a swine model. In nine swine, nine arteries nourishing the colon were embolized with NBCA-Lp (1 ml of NBCA mixed with 4 ml of lipiodol): sigmoid-rectal branch artery in six swine, right colic branch artery in two, and middle colic branch artery in one. The amount of NBCA-Lp was 0.1-0.4 ml. Sacrifice was conducted 3 days after TAE to identify histological infarction. Classification was conducted retrospectively: group A, vasa recta without NBCA-Lp embolization despite TAE; group B, three or fewer vasa recta with NBCA-Lp embolization; and group C, five or more vasa recta with NBCA-Lp embolization. In one swine in group A, no necrotic focus was observed. In group B, three of four swine experienced no ischemic damage. The remaining one swine experienced necrosis of mucosal and submucosal layers in one-fourth of the circumference. In group C, all four swine with marginal artery and five vasa recta or more embolized experienced total necrosis of mucosa, submucosa, and smooth muscle layers of the whole colonic circumference. Significant difference on the extent of ischemic damage was observed between groups B and C (P < 0.05). Microscopically, NBCA-Lp induced acute vasculitis. Embolization of three or fewer vasa recta with NBCA-Lp induced no ischemic damage or limited necrosis, whereas embolization of five or more vasa recta with NBCA-Lp induced extensive necrosis.

  5. Comparison of atypical Brachyspira spp. clinical isolates and classic strains in a mouse model of swine dysentery.

    PubMed

    Burrough, Eric; Strait, Erin; Kinyon, Joann; Bower, Leslie; Madson, Darin; Schwartz, Kent; Frana, Timothy; Songer, J Glenn

    2012-12-07

    Multiple Brachyspira spp. can colonize the porcine colon, and the presence of the strongly beta-hemolytic Brachyspira hyodysenteriae is typically associated with clinical swine dysentery. Recently, several Brachyspira spp. have been isolated from the feces of pigs with clinical disease suggestive of swine dysentery, yet these isolates were not identified as B. hyodysenteriae by genotypic or phenotypic methods. This study used a mouse model of swine dysentery to compare the pathogenic potential of seventeen different Brachyspira isolates including eight atypical clinical isolates, six typical clinical isolates, the standard strain of B. hyodysenteriae (B204), and reference strains of Brachyspira intermedia and Brachyspira innocens. Results revealed that strongly beta-hemolytic isolates induced significantly greater cecal inflammation than weakly beta-hemolytic isolates regardless of the genetic identification of the isolate, and that strongly beta-hemolytic isolates identified as 'Brachyspira sp. SASK30446' and B. intermedia by PCR produced lesions indistinguishable from those caused by B. hyodysenteriae in this model.

  6. Development of a Swine Benign Biliary Stricture Model Using Endoscopic Biliary Radiofrequency Ablation

    PubMed Central

    2016-01-01

    The large animal model with benign biliary stricture (BBS) is essential to undergo experiment on developing new devices and endoscopic treatment. This study conducted to establish a clinically relevant porcine BBS model by means of endobiliary radiofrequency ablation (RFA). Endoscopic retrograde cholangiography (ERC) was performed on 12 swine. The animals were allocated to three groups (60, 80, and 100 W) according to the electrical power level of RFA electrode. Endobiliary RFA was applied to the common bile duct for 60 seconds using an RFA catheter that was endoscopically inserted. ERC was repeated two and four weeks, respectively, after the RFA to identify BBS. After the strictures were identified, histologic evaluations were performed. On the follow-up ERC two weeks after the procedure, a segmental bile duct stricture was observed in all animals. On microscopic examination, severe periductal fibrosis and luminal obliteration with transmural inflammation were demonstrated. Bile duct perforations occurred in two pigs (100 W, n = 1; 80 W, n = 1) but there were no major complications in the 60 W group. The application of endobiliary RFA with 60 W electrical power resulted in a safe and reproducible swine model of BBS. PMID:27510388

  7. A Multiscale Computational Model of the Response of Swine Epidermis After Acute Irradiation

    NASA Technical Reports Server (NTRS)

    Hu, Shaowen; Cucinotta, Francis A.

    2012-01-01

    Radiation exposure from Solar Particle Events can lead to very high skin dose for astronauts on exploration missions outside the protection of the Earth s magnetic field [1]. Assessing the detrimental effects to human skin under such adverse conditions could be predicted by conducting territorial experiments on animal models. In this study we apply a computational approach to simulate the experimental data of the radiation response of swine epidermis, which is closely similar to human epidermis [2]. Incorporating experimentally measured histological and cell kinetic parameters into a multiscale tissue modeling framework, we obtain results of population kinetics and proliferation index comparable to unirradiated and acutely irradiated swine experiments [3]. It is noted the basal cell doubling time is 10 to 16 days in the intact population, but drops to 13.6 hr in the regenerating populations surviving irradiation. This complex 30-fold variation is proposed to be attributed to the shortening of the G1 phase duration. We investigate this radiation induced effect by considering at the sub-cellular level the expression and signaling of TGF-beta, as it is recognized as a key regulatory factor of tissue formation and wound healing [4]. This integrated model will allow us to test the validity of various basic biological rules at the cellular level and sub-cellular mechanisms by qualitatively comparing simulation results with published research, and should lead to a fuller understanding of the pathophysiological effects of ionizing radiation on the skin.

  8. Short-term Safety and Efficiency of Cryoablation for Renal Sympathetic Denervation in a Swine Model

    PubMed Central

    Ji, Meng; Shen, Li; Wu, Yi-Zhe; Yao, Zhi-Feng; Yin, Jia-Sheng; Chen, Jia-Hui; Jia, Jian-Guo; Qiao, Ling-Juan; Liu, Peng; Ge, Jun-Bo

    2015-01-01

    Background: Renal sympathetic nerves are involved in the reflective activation of the sympathetic nervous system in circulatory control. Catheter-based renal denervation (RDN) ameliorated treatment-resistant hypertension safely, but 10%–20% of treated patients are nonresponders to radiofrequency denervation. The purpose of this study was to investigate the safety and efficiency of cryoablation for sympathetic denervation in a swine model and to explore a new way of RDN. Methods: Seven swines randomly assigned to two groups: Renal cryoablation (CR) group and control group. The control group underwent renal angiogram only. The CR group underwent renal angiogram plus bilateral renal cryoablation. Renal angiograms via femoral were performed before denervation, after denervation and prior to the sacrifice to access the diameter of renal arterial and the pressure of aorta abdominalis. Euthanasia of the swine was performed on 28-day to access norepinephrine (NE) changes of the renal cortex and the changes of renal nerves. Results: Cryoablation did not induce severe complications at any time point. There was no significant change in diameter of renal artery. CR reduced systolic blood pressure (BP) from 145.50 ± 9.95 mmHg at baseline to 119.00 ± 14.09 mmHg. There was a slight but insignificant decrease in diastolic BP. The main nerve changes at 28-day consisted of necrosis with perineurial fibrosis at the site of CR exposure in conjunction with the nerve vacuolation. Compared with the control group, renal tissue NE of CR group decreased by 89.85%. Conclusions: Percutaneous catheter-based cryoablation of the renal artery is safe. CR could effectively reduce NE storing in the renal cortex, and the efficiency could be maintained 28-day at least. PMID:25758274

  9. Juvenile Swine Surgical Alveolar Cleft Model to Test Novel Autologous Stem Cell Therapies.

    PubMed

    Caballero, Montserrat; Morse, Justin C; Halevi, Alexandra E; Emodi, Omri; Pharaon, Michael R; Wood, Jeyhan S; van Aalst, John A

    2015-09-01

    Reconstruction of craniofacial congenital bone defects has historically relied on autologous bone grafts. Engineered bone using mesenchymal stem cells from the umbilical cord on electrospun nanomicrofiber scaffolds offers an alternative to current treatments. This preclinical study presents the development of a juvenile swine model with a surgically created maxillary cleft defect for future testing of tissue-engineered implants for bone generation. Five-week-old pigs (n=6) underwent surgically created maxillary (alveolar) defects to determine critical-sized defect and the quality of treatment outcomes with rib, iliac crest cancellous bone, and tissue-engineered scaffolds. Pigs were sacrificed at 1 month. Computed tomography scans were obtained at days 0 and 30, at the time of euthanasia. Histological evaluation was performed on newly formed bone within the surgical defect. A 1 cm surgically created defect healed with no treatment, the 2 cm defect did not heal. A subsequently created 1.7 cm defect, physiologically similar to a congenitally occurring alveolar cleft in humans, from the central incisor to the canine, similarly did not heal. Rib graft treatment did not incorporate into adjacent normal bone; cancellous bone and the tissue-engineered graft healed the critical-sized defect. This work establishes a juvenile swine alveolar cleft model with critical-sized defect approaching 1.7 cm. Both cancellous bone and tissue engineered graft generated bridging bone formation in the surgically created alveolar cleft defect.

  10. Characterization of Dendritic Cells Subpopulations in Skin and Afferent Lymph in the Swine Model

    PubMed Central

    Marquet, Florian; Bonneau, Michel; Pascale, Florentina; Urien, Celine; Kang, Chantal; Schwartz-Cornil, Isabelle; Bertho, Nicolas

    2011-01-01

    Transcutaneous delivery of vaccines to specific skin dendritic cells (DC) subsets is foreseen as a promising strategy to induce strong and specific types of immune responses such as tolerance, cytotoxicity or humoral immunity. Because of striking histological similarities between human and pig skin, pig is recognized as the most suitable model to study the cutaneous delivery of medicine. Therefore improving the knowledge on swine skin DC subsets would be highly valuable to the skin vaccine field. In this study, we showed that pig skin DC comprise the classical epidermal langerhans cells (LC) and dermal DC (DDC) that could be divided in 3 subsets according to their phenotypes: (1) the CD163neg/CD172aneg, (2) the CD163highCD172apos and (3) the CD163lowCD172apos DDC. These subtypes have the capacity to migrate from skin to lymph node since we detected them in pseudo-afferent lymph. Extensive phenotyping with a set of markers suggested that the CD163high DDC resemble the antibody response-inducing human skin DC/macrophages whereas the CD163negCD172low DDC share properties with the CD8+ T cell response-inducing murine skin CD103pos DC. This work, by showing similarities between human, mouse and swine skin DC, establishes pig as a model of choice for the development of transcutaneous immunisation strategies targeting DC. PMID:21298011

  11. Co-liquefaction of swine manure and crude glycerol to bio-oil: model compound studies and reaction pathways.

    PubMed

    Ye, Zhangying; Xiu, Shuangning; Shahbazi, Abolghasem; Zhu, Songming

    2012-01-01

    The reaction pathways of co-liquefaction of swine manure and crude glycerol to bio-oil (ester compounds) were investigated. Swine manure was hydrothermal treated (340 °C, 27.5 MPa, 15 min) with a number of model compounds in a high pressure batch reactor under inert atmosphere. The compounds were methanol, pure glycerol, mixture of pure glycerol, pure methanol and H(2)O, and commercial fatty acids (linoleic acid). The chemical composition of the bio-oil was analyzed by GC/MS. Glycerol, methanol and water showed synergistic effects on manure liquefaction, increasing the oil yield as high as 65%. A maximum oil yield of 79.96% was obtained when linoleic acid reacted with swine manure. Based on the results, the reaction pathways were proposed. Esterification reactions occurred not only because the crude glycerol have methanol, but also because methanol can be produced from hydrothermal reactions of glycerol.

  12. A simple approach to modeling ductile failure.

    SciTech Connect

    Wellman, Gerald William

    2012-06-01

    Sandia National Laboratories has the need to predict the behavior of structures after the occurrence of an initial failure. In some cases determining the extent of failure, beyond initiation, is required, while in a few cases the initial failure is a design feature used to tailor the subsequent load paths. In either case, the ability to numerically simulate the initiation and propagation of failures is a highly desired capability. This document describes one approach to the simulation of failure initiation and propagation.

  13. Development of Improved Dynamic Failure Models.

    DTIC Science & Technology

    1985-02-15

    M 1.35 g/cm3 ) was used to produce a Chapman - Jouguet pressure of 16.3 GPa. The cylinder was surrounded by a PMHA tube of 1.15 cm thickness and a steel...3 mproved computational models were developed for dynamic material failure by Shear banding and ductile fracture. The research effort involved theory ...Cylinder at 56 ps After Detonation ..................... VI-41 ý,r I.4 I.P VI.2 Fragment (a) of 4340 Steel Cylinder (RC 40) and Photomicrographs (b and c) of

  14. Estimating Failure Propagation in Models of Cascading Blackouts

    SciTech Connect

    Dobson, Ian; Carreras, Benjamin A; Lynch, Vickie E; Nkei, Bertrand; Newman, David E

    2005-09-01

    We compare and test statistical estimates of failure propagation in data from versions of a probabilistic model of loading-dependent cascading failure and a power systems blackout model of cascading transmission line overloads. The comparisons suggest mechanisms affecting failure propagation and are an initial step towards monitoring failure propagation from practical system data. Approximations to the probabilistic model describe the forms of probability distributions of cascade sizes.

  15. Swine alveolar macrophage cell model allows optimal replication of influenza A viruses regardless of their origin.

    PubMed

    Kasloff, Samantha B; Weingartl, Hana M

    2016-03-01

    The importance of pigs in interspecies transmission of influenza A viruses has been repeatedly demonstrated over the last century. Eleven influenza A viruses from avian, human and swine hosts were evaluated for replication phenotypes at three physiologically relevant temperatures (41°C, 37°C, 33°C) in an immortalized swine pulmonary alveolar macrophage cell line (IPAM 3D4/31) to determine whether this system would allow for their efficient replication. All isolates replicated well in IPAMs at 37°C while clear distinctions were observed at 41°C and 33°C, correlating to species of origin of the PB2, reflected in distinct amino acid residue profiles rather than in one particular PB2 residue. A strong TNF-α response was induced by some mammalian but not avian IAVs, while other selected cytokines remained below detection levels. Porcine IPAMs represent a natural host cell model for influenza virus replication where the only condition requiring modification for optimal IAV replication, regardless of virus origin.

  16. Myelogenous Leukemia in Adult Inbred MHC Defined Miniature Swine: a model for human myeloid leukemias

    PubMed Central

    Cho, Patricia S.; Teague, Alexander G.S.; Fishman, Brian; Fishman, Aaron S.; Hanekamp, John S.; Moran, Shannon G.; Wikiel, Krzysztof J.; Ferguson, Kelly K.; Lo, Diana P.; Duggan, Michael; Arn, J. Scott; Billiter, Bob; Horner, Ben; Houser, Stuart; Yeap, Beow Yong; Westmoreland, Susan V.; Spitzer, Thomas R.; McMorrow, Isabel M.; Sachs, David H.; Bronson, Roderick T; Huang, Christene A.

    2010-01-01

    This manuscript reports on five cases of spontaneous myelogenous leukemia, similar to human disease, occurring within highly inbred, histocompatible sublines of Massachusetts General Hospital (MGH) MHC-defined miniature swine. In cases where a neoplasm was suspected based on clinical observations, samples were obtained for complete blood count, peripheral blood smear, and flow cytometric analysis. Animals confirmed to have neoplasms were euthanized and underwent necropsy. Histological samples were obtained from abnormal tissues and suspect lesions. The phenotype of the malignancies was assessed by flow cytometric analysis of processed peripheral blood mononuclear cells and affected tissues. Five cases of spontaneous myeloid leukemia were identified in adult animals older than 30 months of age. All animals presented with symptoms of weight loss, lethargy, and marked leukocytosis. At autopsy, all animals had systemic disease involvement and presented with severe hepatosplenomegaly. Three of the five myelogenous leukemias have successfully been expanded in vitro. The clustered incidence of disease in this closed herd suggests that genetic factors may be contributing to disease development. Myelogenous leukemia cell lines established from inbred sublines of MGH MHC-defined miniature swine have the potential to be utilized as a model to evaluate therapies of human leukemia. PMID:20079939

  17. Miniature swine and in vitro studies as models of human iron bioavailability

    SciTech Connect

    Reddy, M.; Browder, B.; Jordan, M.; Bates, G.

    1986-03-05

    Iron bioavailability is ultimately dependent upon ligand exchange reactions between mucosal iron receptor proteins and iron binding ligands present in the digestive mass. This exchange reaction depends upon the chemistry of iron during digestion, its oxidation, reduction, polymerization, precipitation and adsorption to solid surfaces. The authors have investigated these phenomena using miniature Sinclair swine with gastric and duodenal cannula and in vitro enzymatic digestion. Cooked pinto beans have been our food model. In vitro studies demonstrate the importance of reductive iron release reactions at low pH in the presence of reductants and chelate mediated iron mobilization near neutral pH. They found the redox state of iron in the digestive mass to be closely linked to pH. The pH in the duodenum of swine ranges from 2 to 6 depending on the time of digestion, nature of additives and amount of food given. In the authors study they have utilized pinto beans in the presence of ascorbate, citrate, phosvitin, tea, and other food components. The principle difference observed in iron chemistry between the in vitro and in vivo digestion is a greater fraction of Fe/sup 2 +/ in the latter. Electron paramagnetic resonance (EPR) spectroscopy is used to monitor the presence of iron in the Fe/sup 3 +/ state and the reactivity of iron with Fe/sup 3 +/ preferring chelators.

  18. Environmental Effectiveness of Swine Sewage Management: A Multicriteria AHP-Based Model for a Reliable Quick Assessment

    NASA Astrophysics Data System (ADS)

    Vizzari, Marco; Modica, Giuseppe

    2013-10-01

    Environmental issues related to swine production are still a major concern for the general public and represent a key challenge for the swine industry. The environmental impact of higher livestock concentration is particularly significant where it coincides with weaker policy standards and poor manure management. Effective tools for environmental monitoring of the swine sewage management process become essential for verifying the environmental compatibility of farming facilities and for defining suitable policies aimed at increasing swine production sustainability. This research aims at the development and application of a model for a quick assessment of the environmental effectiveness of the pig farming sewage management process. In order to define the model, multicriteria techniques, and in particular, Saaty's analytic hierarchy process, were used to develop an iterative process in which the various key factors influencing the process under investigation were analyzed. The model, named EASE (Environmental Assessment of Sewages management Effectiveness), was optimized and applied to the Lake Trasimeno basin (Umbria, Italy), an area of high natural, environmental and aesthetic value. In this context, inadequate disposal of pig sewage represents a potential source of very considerable pollution. The results have demonstrated how the multicriteria model can represent a very effective and adaptable tool also in those decision-making processes aimed at the sustainable management of livestock production.

  19. Semi-empirical process-based models for ammonia emissions from beef, swine, and poultry operations in the United States

    NASA Astrophysics Data System (ADS)

    McQuilling, Alyssa M.; Adams, Peter J.

    2015-11-01

    Farm-level ammonia emissions factors in the literature vary by an order of magnitude due to variations in manure management practices and meteorology, and it is essential to capture this variability in emission inventories used for atmospheric modeling. Loss of ammonia to the atmosphere is modeled here through a nitrogen mass balance with losses controlled by mass transfer resistance parameters, which vary with meteorological conditions and are tuned to match literature-reported emissions factors. Variations due to management practices are captured by having tuned parameters that are specific to each set of management practices. The resulting farm emissions models (FEMs) explain between 20% and 70% of the variability in published emissions factors and typically estimate emission factors within a factor of 2. The r2 values are: 0.53 for swine housing (0.67 for shallow-pit houses); 0.48 for swine storage; 0.29 for broiler chickens; 0.70 for layer chickens; and 0.21 for beef feedlots (0.36 for beef feedlots with more farm-specific input data). Mean fractional error was found to be 22-44% for beef feedlots, swine housing, and layer housing; fractional errors were greater for swine lagoons (90%) and broiler housing (69%). Unexplained variability and errors result from model limitations, measurement errors in reported emissions factors, and a lack of information about measurement conditions.

  20. Environmental effectiveness of swine sewage management: a multicriteria AHP-based model for a reliable quick assessment.

    PubMed

    Vizzari, Marco; Modica, Giuseppe

    2013-10-01

    Environmental issues related to swine production are still a major concern for the general public and represent a key challenge for the swine industry. The environmental impact of higher livestock concentration is particularly significant where it coincides with weaker policy standards and poor manure management. Effective tools for environmental monitoring of the swine sewage management process become essential for verifying the environmental compatibility of farming facilities and for defining suitable policies aimed at increasing swine production sustainability. This research aims at the development and application of a model for a quick assessment of the environmental effectiveness of the pig farming sewage management process. In order to define the model, multicriteria techniques, and in particular, Saaty's analytic hierarchy process, were used to develop an iterative process in which the various key factors influencing the process under investigation were analyzed. The model, named EASE (Environmental Assessment of Sewages management Effectiveness), was optimized and applied to the Lake Trasimeno basin (Umbria, Italy), an area of high natural, environmental and aesthetic value. In this context, inadequate disposal of pig sewage represents a potential source of very considerable pollution. The results have demonstrated how the multicriteria model can represent a very effective and adaptable tool also in those decision-making processes aimed at the sustainable management of livestock production.

  1. Dispersion modeling to compare alternative technologies for odor remediation at swine facilities.

    PubMed

    Schiffman, Susan S; Graham, Brevick G; Williams, C Mike

    2008-09-01

    The effectiveness of 18 alternative technologies for reducing odor dispersion at and beyond the boundary of swine facilities was assessed in conjunction with an initiative sponsored through agreements between the Attorney General of North Carolina and Smithfield Foods, Premium Standard Farms, and Frontline Farmers. The trajectory and spatial distribution of odor emitted at each facility were modeled at 200 and 400 m downwind from each site under two meteorological conditions (daytime and nighttime) using a Eulerian-Lagrangian model. To predict the dispersion of odor downwind, the geographical area containing the odorant sources at each facility was partitioned into 10-m2 grids on the basis of satellite photographs and architectural drawings. Relative odorant concentrations were assigned to each grid point on the basis of intensity measurements made by the trained odor panel at each facility using a 9-point rating scale. The results of the modeling indicated that odor did not extend significantly beyond 400 m downwind of any of the test sites during the daytime when the layer of air above the earth's surface is usually turbulent. However, modeling indicated that odor from all full-scale farms extended beyond 400 m onto neighboring property in the evenings when deep surface cooling through long-wave radiation to space produces a stable (nocturnal) boundary layer. The results also indicated that swine housing, independent of waste management type, plays a significant role in odor downwind, as do odor sources of moderate to moderately high intensity that emanate from a large surface area such as a lagoon. Human odor assessments were utilized for modeling rather than instrument measurements of volatile organic compounds (VOCs), hydrogen sulfide, ammonia, or particulates less than 10 microm in diameter (PM10) because these physical measurements obtained simultaneously with human panel ratings were not found to accurately predict human odor intensity in the field.

  2. A swine model of acute thrombocytopenia with prolonged bleeding time produced by busulfan

    PubMed Central

    Abe, Tomoyuki; Kono, Shota; Ohnuki, Takahiro; Hishikawa, Shuji; Kunita, Satoshi; Hanazono, Yutaka

    2016-01-01

    Animal models of thrombocytopenia are indispensable for evaluating the in vivo efficacy of hemostatic agents, cryopreserved platelets, and artificial platelets, but no large animal models are available. In this study, we generated a swine model of acute thrombocytopenia with prolonged bleeding times by administering the chemotherapeutic drug busulfan. First, we tested multiple doses of busulfan (4, 6, and 8 mg/kg) in pigs, and found that 6 mg/kg of busulfan is an optimal dose for producing a safe and moderate thrombocytopenia, with a platelet count of less than 30,000/µl. The pigs administered 6 mg/kg of busulfan (n=8) reached half their initial counts at day 7, counts below 30,000/µl at day 12, and their nadirs at day 15 (on average). The minimal platelet count was 14,000/µl. With this dose of busulfan (6 mg/kg), bleeding times were significantly prolonged in addition to the decrease in platelet counts (r=−0.63, P<0.01), while there were no cases of apparent hemorrhage. White blood cell counts were maintained at over 5,000/µl, and there were no infections or other adverse events including anemia or appetite or body weight loss. All pigs were sacrificed on day 16, with subsequent examination showing a significant reduction in cellularity and colony-forming units in the bone marrow, indicating that thrombocytopenia was the result of myelosuppression. In summary, administration with 6 mg/kg of busulfan induces safe and moderate thrombocytopenia with a prolonged bleeding time in swine. PMID:27333841

  3. A wind tunnel study of air flow near model swine confinement buildings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One of the most significant and persistent environmental concerns regarding swine production is the transport of odor constituents, trace gases, and particulates from animal production and manure storage facilities. The objectives of this study were to determine how swine housing unit orientation af...

  4. Is a Swine Model of Arteriovenous Malformation Suitable for Human Extracranial Arteriovenous Malformation? A Preliminary Study

    SciTech Connect

    Lv, Ming-ming; Fan, Xin-dong; Su, Li-xin

    2013-10-15

    Objective: A chronic arteriovenous malformation (AVM) model using the swine retia mirabilia (RMB) was developed and compared with the human extracranial AVM (EAVM) both in hemodynamics and pathology, to see if this brain AVM model can be used as an EAVM model. Methods: We created an arteriovenous fistula between the common carotid artery and the external jugular vein in eight animals by using end-to-end anastomosis. All animals were sacrificed 1 month after surgery, and the bilateral retia were obtained at autopsy and performed hematoxylin and eosin staining and immunohistochemistry. Pre- and postsurgical hemodynamic evaluations also were conducted. Then, the blood flow and histological changes of the animal model were compared with human EAVM. Results: The angiography after operation showed that the blood flow, like human EAVM, flowed from the feeding artery, via the nidus, drained to the draining vein. Microscopic examination showed dilated lumina and disrupted internal elastic lamina in both RMB of model and nidus of human EAVM, but the thickness of vessel wall had significant difference. Immunohistochemical reactivity for smooth muscle actin, angiopoietin 1, and angiopoietin 2 were similar in chronic model nidus microvessels and human EAVM, whereas vascular endothelial growth factor was significant difference between human EAVM and RMB of model. Conclusions: The AVM model described here is similar to human EAVM in hemodynamics and immunohistochemical features, but there are still some differences in anatomy and pathogenetic mechanism. Further study is needed to evaluate the applicability and efficacy of this model.

  5. UPDATE ON SWINE DISEASE AND GENOMICS RESEARCH

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This review will summarize advances in swine genomics and how it has altered approaches for swine disease and vaccination research. The swine has been a major biomedical model species, for transplantation, heart disease, allergies and asthma, as well as normal neonatal development and reproductive p...

  6. Selective rod degeneration and partial cone inactivation characterize an iodoacetic acid model of Swine retinal degeneration.

    PubMed

    Wang, Wei; Fernandez de Castro, Juan; Vukmanic, Eric; Zhou, Liang; Emery, Douglas; Demarco, Paul J; Kaplan, Henry J; Dean, Douglas C

    2011-10-07

    PURPOSE. Transgenic pigs carrying a mutant human rhodopsin transgene have been developed as a large animal model of retinitis pigmentosa (RP). This model displays some key features of human RP, but the time course of disease progression makes this model costly, time consuming, and difficult to study because of the size of the animals at end-stage disease. Here, the authors evaluate an iodoacetic acid (IAA) model of photoreceptor degeneration in the pig as an alternative model that shares features of the transgenic pig and human RP. METHODS. IAA blocks glycolysis, thereby inhibiting photoreceptor function. The effect of the intravenous injection of IAA on swine rod and cone photoreceptor viability and morphology was followed by histologic evaluation of different regions of the retina using hematoxylin and eosin and immunostaining. Rod and cone function was analyzed by full-field electroretinography and multifocal electroretinography. RESULTS. IAA led to specific loss of rods in a central-to-peripheral retinal gradient. Although cones were resistant, they showed shortened outer segments, loss of bipolar cell synaptic connections, and a diminished flicker ERG, hallmarks of transition to cone dysfunction in RP patients. CONCLUSIONS. IAA provides an alternative rod-dominant model of retinal damage that shares a surprising number of features with the pig transgenic model of RP and with human RP. This IAA model is cost-effective and rapid, ensuring that the size of the animals does not become prohibitive for end-stage evaluation or therapeutic intervention.

  7. Multiscale modeling of failure in composites under model parameter uncertainty

    NASA Astrophysics Data System (ADS)

    Bogdanor, Michael J.; Oskay, Caglar; Clay, Stephen B.

    2015-09-01

    This manuscript presents a multiscale stochastic failure modeling approach for fiber reinforced composites. A homogenization based reduced-order multiscale computational model is employed to predict the progressive damage accumulation and failure in the composite. Uncertainty in the composite response is modeled at the scale of the microstructure by considering the constituent material (i.e., matrix and fiber) parameters governing the evolution of damage as random variables. Through the use of the multiscale model, randomness at the constituent scale is propagated to the scale of the composite laminate. The probability distributions of the underlying material parameters are calibrated from unidirectional composite experiments using a Bayesian statistical approach. The calibrated multiscale model is exercised to predict the ultimate tensile strength of quasi-isotropic open-hole composite specimens at various loading rates. The effect of random spatial distribution of constituent material properties on the composite response is investigated.

  8. Calpain Inhibition Improves Collateral Dependent Perfusion in a Hypercholesterolemic Swine Model of Chronic Myocardial Ischemia

    PubMed Central

    Sabe, Ashraf A.; Potz, Brittany A.; Elmadhun, Nassrene Y.; Liu, Yuhong; Feng, Jun; Abid, M. Ruhul; Abbott, Jinnette D; Senger, Donald R; Sellke, Frank W.

    2015-01-01

    Background Calpain over-expression is implicated in aberrant angiogenesis. We hypothesized that calpain inhibition (CI, MDL28170) would improve collateral perfusion in a swine model with hypercholesterolemia and chronic myocardial ischemia. Methods and Results Yorkshire swine fed a high cholesterol diet for 4 weeks underwent surgical placement of an ameroid constrictor to their left circumflex coronary artery. Three weeks later, animals received either: no drug, high cholesterol control group (HCC; n= 8); low dose CI (0.12 mg/kg; LCI, n= 9); or high dose CI (0.25 mg/kg; HCI, n= 8). The heart was harvested after 5 weeks. There was a trend toward increased right to left collateral vessels on angiography with HCI. Myocardial perfusion in ischemic myocardium significantly improved with HCI at rest and with demand pacing (p = 0.016 and 0.011). Endothelium-dependent microvessel relaxation was significantly improved with LCI (p = 0.001). There was a significant increase in capillary density, with LCI and HCI (p= 0.01 and 0.01), and arteriolar density with LCI (p= 0.001). CI significantly increased several proangiogenic proteins including VEGF (p= 0.02), VEGFR1 (p= 0.003), VEGFR2 (p= 0.003) and talin, a microvascular structural protein (p= 0.0002). There was a slight increase in proteins implicated in endothelial-dependent (NO Mediated) relaxation including ERK, p-ERK and iNOS with CI. Conclusions In the setting of hypercholesterolemia, CI improved perfusion, with a trend toward increased collateralization on angiography and increased capillary and arteriolar densities in ischemic myocardium. CI also improved endothelium-dependent microvessel relaxation and increased expression of proteins implicated in angiogenesis and vasodilatation. PMID:26478238

  9. Fibrinogen concentrate improves survival during limited resuscitation of uncontrolled hemorrhagic shock in a Swine model.

    PubMed

    White, Nathan J; Wang, Xu; Liles, Conrad; Stern, Susan

    2014-11-01

    The purpose of this study was to evaluate the effect of fibrinogen concentrate, as a hemostatic agent, on limited resuscitation of uncontrolled hemorrhagic shock. We use a swine model of hemorrhagic shock with free bleeding from a 4-mm aortic tear to test the effect of adding a one-time dose of fibrinogen concentrate given at the onset of limited fluid resuscitation. Immature female swine were anesthetized and subjected to catheter hemorrhage and aortic tear to induce uniform hemorrhagic shock. Animals (n = 7 per group) were then randomized to receive (i) no fluid resuscitation (neg control) or (ii) limited resuscitation in the form of two boluses of 10 mL/kg of 6% hydroxyethyl starch solution given 30 min apart (HEX group), or (iii) the same fluid regimen with one dose of 120-mg/kg fibrinogen concentrate given with the first hydroxyethyl starch bolus (FBG). Animals were then observed for a total of 6 h with aortic repair and aggressive resuscitation with shed blood taking place at 3 h. Survival to 6 h was significantly increased with FBG (7/8, 86%) versus HEX (2/7, 29%) and neg control (0/7, 0%) (FBG vs. HEX, Kaplan-Meier log-rank P = 0.035). Intraperitoneal blood loss adjusted for survival time was increased in HEX (0.4 mL/kg per minute) when compared with FBG (0.1 mg/kg per minute, P = 0.047) and neg control (0.1 mL/kg per minute, P = 0.041). Systemic and cerebral hemodynamics also showed improvement with FBG versus HEX. Fibrinogen concentrate may be a useful adjunct to decrease blood loss, improve hemodynamics, and prolong survival during limited resuscitation of uncontrolled hemorrhagic shock.

  10. Fibrinogen Concentrate Improves Survival During Limited Resuscitation of Uncontrolled Hemorrhagic Shock in a Swine Model

    PubMed Central

    White, Nathan J.; Wang, Xu; Liles, W. Conrad; Stern, Susan

    2014-01-01

    The purpose of this study was to evaluate the effect of fibrinogen concentrate, as a hemostatic agent, on limited resuscitation of uncontrolled hemorrhagic shock. We use a swine model of hemorrhagic shock with free bleeding from a 4mm aortic tear to test the effect of adding a one-time dose of fibrinogen concentrate given at the onset of limited fluid resuscitation. Immature female swine were anesthetized and subjected to catheter hemorrhage and aortic tear to induce uniform hemorrhagic shock. Animals (N=7 per group) were then randomized to receive either; 1. No fluid resuscitation (Neg Control), 2. Limited resuscitation in the form of two boluses of 10ml/kg of 6% hydroxyethyl starch solution (HEX) given 30 minutes apart, or 3. The same fluid regimen with one dose of 120mg/kg fibrinogen concentrate given with the first HEX bolus (FBG). Animals were then observed for a total of 6 hours with aortic repair and aggressive resuscitation with shed blood taking place at 3 hours. Survival to 6 hours was significantly increased with FBG (7/8, 86%) vs. HEX (2/7, 29%), and Neg Control (0/7, 0%) (FBG vs. HEX, Kaplan Meier LR p=0.035). Intraperitoneal blood loss adjusted for survival time was increased in HEX (0.4ml/kg/min) when compared to FBG (0.1mg/kg/min, p=0.047) and Neg Control (0.1ml/kg/min, p=0.041). Systemic and cerebral hemodynamics also showed improvement with FBG vs. HEX. Fibrinogen concentrate may be a useful adjunct to decrease blood loss, improve hemodynamics, and prolong survival during limited resuscitation of uncontrolled hemorrhagic shock. PMID:25337778

  11. Modeled Effectiveness of Ventilation with Contaminant Control Devices on Indoor Air Quality in a Swine Farrowing Facility

    PubMed Central

    Anthony, T. Renée; Altmaier, Ralph; Park, Jae Hong; Peters, Thomas M.

    2016-01-01

    Because adverse health effects experienced by swine farm workers in concentrated animal feeding operations (CAFOs) have been associated with exposure to dust and gases, efforts to reduce exposures are warranted, particularly in winter seasons when exposures increase due to decreased ventilation. Simulation of air quality and operating costs for ventilating swine CAFO, including treating and recirculating air through a farrowing room, was performed using mass and energy balance equations over a 90-day winter season. System operation required controlling heater operation to achieve room temperatures optimal to ensure animal health (20 to 22.5°C). Five air pollution control devices, four room ventilation rates, and five recirculation patterns were examined. Inhalable dust concentrations were easily reduced using standard industrial air pollution control devices, including a cyclone, filtration, and electrostatic precipitator. Operating ventilation systems at 0.94 m3 s−1 (2000 cfm) with 75 to 100% recirculation of treated air from cyclone, electrostatic precipitator, and shaker dust filtration system achieves adequate particle control with operating costs under $1.00 per pig produced ($0.22 to 0.54), although carbon dioxide (CO2) concentrations approach 2000 ppm using in-room ventilated gas fired heaters. In no simulation were CO2 concentrations below industry recommended concentrations (1540 ppm), but alternative heating devices could reduce CO2 to acceptable concentrations. While this investigation does not represent all production swine farrowing barns, which differ in characteristics including room dimensions and swine occupancy, the simulation model and ventilation optimization methods can be applied to other production sites. This work shows that ventilation may be a cost-effective control option in the swine industry to reduce exposures. PMID:24433305

  12. Modeled effectiveness of ventilation with contaminant control devices on indoor air quality in a swine farrowing facility.

    PubMed

    Anthony, T Renée; Altmaier, Ralph; Park, Jae Hong; Peters, Thomas M

    2014-01-01

    Because adverse health effects experienced by swine farm workers in concentrated animal feeding operations (CAFOs) have been associated with exposure to dust and gases, efforts to reduce exposures are warranted, particularly in winter seasons when exposures increase due to decreased ventilation. Simulation of air quality and operating costs for ventilating swine CAFO, including treating and recirculating air through a farrowing room, was performed using mass and energy balance equations over a 90-day winter season. System operation required controlling heater operation to achieve room temperatures optimal to ensure animal health (20 to 22.5 °C). Five air pollution control devices, four room ventilation rates, and five recirculation patterns were examined. Inhalable dust concentrations were easily reduced using standard industrial air pollution control devices, including a cyclone, filtration, and electrostatic precipitator. Operating ventilation systems at 0.94 m3 s(-1) (2000 cfm) with 75 to 100% recirculation of treated air from cyclone, electrostatic precipitator, and shaker dust filtration system achieves adequate particle control with operating costs under $1.00 per pig produced ($0.22 to 0.54), although carbon dioxide (CO2) concentrations approach 2000 ppm using in-room ventilated gas fired heaters. In no simulation were CO2 concentrations below industry recommended concentrations (1540 ppm), but alternative heating devices could reduce CO2 to acceptable concentrations. While this investigation does not represent all production swine farrowing barns, which differ in characteristics including room dimensions and swine occupancy, the simulation model and ventilation optimization methods can be applied to other production sites. This work shows that ventilation may be a cost-effective control option in the swine industry to reduce exposures.

  13. Exploring the mechanical behavior of degrading swine neural tissue at low strain rates via the fractional Zener constitutive model.

    PubMed

    Bentil, Sarah A; Dupaix, Rebecca B

    2014-02-01

    The ability of the fractional Zener constitutive model to predict the behavior of postmortem swine brain tissue was examined in this work. Understanding tissue behavior attributed to degradation is invaluable in many fields such as the forensic sciences or cases where only cadaveric tissue is available. To understand how material properties change with postmortem age, the fractional Zener model was considered as it includes parameters to describe brain stiffness and also the parameter α, which quantifies the viscoelasticity of a material. The relationship between the viscoelasticity described by α and tissue degradation was examined by fitting the model to data collected in a previous study (Bentil, 2013). This previous study subjected swine neural tissue to in vitro unconfined compression tests using four postmortem age groups (<6h, 24h, 3 days, and 1 week). All samples were compressed to a strain level of 10% using two compressive rates: 1mm/min and 5mm/min. Statistical analysis was used as a tool to study the influence of the fractional Zener constants on factors such as tissue degradation and compressive rate. Application of the fractional Zener constitutive model to the experimental data showed that swine neural tissue becomes less stiff with increased postmortem age. The fractional Zener model was also able to capture the nonlinear viscoelastic features of the brain tissue at low strain rates. The results showed that the parameter α was better correlated with compressive rate than with postmortem age.

  14. Swine in biomedical research. Vol. 3

    SciTech Connect

    Tumbleson, M.E.

    1986-01-01

    This volume presents information on the following topics: hemodynamic characteristics of the conscious resting pig; cardiovascular and metabolic responses to acute and chronic exercise in swine (ILLEGIBLE) a large animal model for studies (ILLEGIBLE) effects of heparin-protamine interaction in swine - intravenous vs. intraarterial; swine as animal models in cardiovascular research; studies of coronary thrombosis in swine with von Willebrand's disease; role of plasma intermediate and low density lipoproteins in early atherogenesis in hyperlipidemic swine; swine as a model in renal physiology and nephrology; the pig as a model for studying kidney disease in man; hypertension of renal origin and the effects of Captopril in miniature pigs; porcine natural killer/killer cell system; the behavior of pig lymphocyte populations in vivo; a review of spontaneous and experimental porcine eperythrozoonosis; and Sinclair swine melanoma.

  15. Measurements and modeling of emissions, dispersion and dry deposition of ammonia from swine facilities

    NASA Astrophysics Data System (ADS)

    Bajwa, Kanwardeep Singh

    Ammonia has recently gained importance for its increasing atmospheric concentrations and its role in the formation of aerosols. Studies have shown increasing atmospheric concentration levels of NH3 and NH 4+, especially in the regions of concentrated animal feeding operations. Atmospheric inputs of reduced nitrogen as ammonia and ammonium by dry and wet deposition may represent a substantial contribution to the acidification of semi natural ecosystems and could also affect sensitive coastal ecosystems and estuaries. The anaerobic lagoon and spray method, commonly used for waste storage and disposal in confined animal feeding operations (CAFO), is a significant source of ammonia emissions. An accurate emission model for ammonia from aqueous surfaces can help in the development of emission factors. Study of dispersion and dry deposition patterns of ammonia downwind of a hog farm will help us to understand how much ammonia gets dry deposited near the farm, and how remaining ammonia gets transported farther away. An experimental and modeling study is conducted of emissions, dispersion and dry deposition of ammonia taking one swine farm as a unit. Measurements of ammonia flux were made at 11 swine facilities in North Carolina using dynamic flow-through chamber system over the anaerobic waste treatment lagoons. Continuous measurements of ammonia flux, meteorological and lagoon parameters were made for 8-10 days at each farm during each of the warm and cold seasons. Ammonia concentrations were continuously measured in the chamber placed over the lagoon using a Thermo Environmental Instrument Incorporated (TECO) Model 17c chemiluminescnce ammonia analyzer. A similar ammonia analyzer was used to measure ammonia concentrations at selected locations on the farm. Barn emissions were measured using open-path Fourier transform infrared (OP-FTIR) spectroscopy. A 10 m meteorological tower was erected at each site to measure wind speed and direction, temperature, relative humidity

  16. Empirical model of odor emission from deep-pit swine finishing barns to derive a standardized odor emission factor

    NASA Astrophysics Data System (ADS)

    Schauberger, Günther; Lim, Teng-Teeh; Ni, Ji-Qin; Bundy, Dwaine S.; Haymore, Barry L.; Diehl, Claude A.; Duggirala, Ravi K.; Heber, Albert J.

    2013-02-01

    Odor emission from swine housing is influenced by the herd characteristics and building environment. The following three specific factors were identified as inputs to a swine house odor emission model: indoor temperature, barn ventilation rate, and pig activity. Model input parameters were determined based on tests of four, identical, 1000-head, mechanically-ventilated swine finishing houses. Each building had two sidewall curtains, a curtain on the west end wall, five exhaust fans on the east end wall, four pit ventilation fans, and long-term manure storage beneath a fully slatted floor. Odor concentrations of 112 odor samples were determined using dynamic forced-choice olfactometry with four to six trained panelists. The emission model showed that the standard live mass specific odor emission factor was 48 OU s-1 per 500 kg live mass or animal unit (AU), and it corresponded to an indoor temperature of T0 = 20 °C, a ventilation rate of V0 = 200 m3 h-1 (55.6 × 10-3 m3 s-1) per pig (maximum capacity for summer time), and the daily mean animal activity. The rate of odor emission from a swine finishing house can be calculated based on these parameters coupled with the number of animals, the mean live mass, and the standard live mass specific odor emission factor. Using this process-based odor emission model, the odor emission estimation and therefore the input for odor dispersion models can be improved to obtain more reliable estimates of separation distance for siting future pig farms.

  17. Swine Influenza (Swine Flu) in Pigs

    MedlinePlus

    ... in the United States since 2005 Prevention Treatment Influenza Types Seasonal Avian Swine/Variant Pandemic Other Get ... Submit Button Past Newsletters Key Facts about Swine Influenza (Swine Flu) in Pigs Language: English Español ...

  18. User-Defined Material Model for Progressive Failure Analysis

    NASA Technical Reports Server (NTRS)

    Knight, Norman F. Jr.; Reeder, James R. (Technical Monitor)

    2006-01-01

    An overview of different types of composite material system architectures and a brief review of progressive failure material modeling methods used for structural analysis including failure initiation and material degradation are presented. Different failure initiation criteria and material degradation models are described that define progressive failure formulations. These progressive failure formulations are implemented in a user-defined material model (or UMAT) for use with the ABAQUS/Standard1 nonlinear finite element analysis tool. The failure initiation criteria include the maximum stress criteria, maximum strain criteria, the Tsai-Wu failure polynomial, and the Hashin criteria. The material degradation model is based on the ply-discounting approach where the local material constitutive coefficients are degraded. Applications and extensions of the progressive failure analysis material model address two-dimensional plate and shell finite elements and three-dimensional solid finite elements. Implementation details and use of the UMAT subroutine are described in the present paper. Parametric studies for composite structures are discussed to illustrate the features of the progressive failure modeling methods that have been implemented.

  19. Sodium Thiosulfate Versus Hydroxocobalamin in the Treatment of Acute, Severe Cyanide Induced Cardiotoxicity in a Swine (Sus Scrofa) Model

    DTIC Science & Technology

    2011-09-22

    intoxicated by cyanide develop cardiac-ar.rest or severely low blood pressure. Currently several antidotes exist, but many have severe adverse effects...machine. They were intoxicated with cyanide (infused through the vein) until the blood pressure was low. The animals were assigned to-one of three...IUIVIJ:lt:M Sodium thiosulfate versus hydroxocoba~amin in the treatment of acute, severe cyanide induced cardiotoxicity in a swine (Sus Scrofa)model on

  20. Conceptual model for heart failure disease management.

    PubMed

    Andrikopoulou, Efstathia; Abbate, Kariann; Whellan, David J

    2014-03-01

    The objective of this review is to propose a conceptual model for heart failure (HF) disease management (HFDM) and to define the components of an efficient HFDM plan in reference to this model. Articles that evaluated 1 or more of the following aspects of HFDM were reviewed: (1) outpatient clinic follow-up; (2) self-care interventions to enhance patient skills; and (3) remote evaluation of worsening HF either using structured telephone support (STS) or by monitoring device data (telemonitoring). The success of programs in reducing readmissions and mortality were mixed. Outpatient follow-up programs generally resulted in improved outcomes, including decreased readmissions. Based on 1 meta-analysis, specialty clinics improved outcomes and nonspecialty clinics did not. Results from self-care programs were inconsistent and might have been affected by patient cognitive status and educational level, and intervention intensity. Telemonitoring, despite initially promising meta-analyses demonstrating a decrease in the number and duration of HF-related readmissions and all-cause mortality rates at follow-up, has not been shown in randomized trials to consistently reduce readmissions or mortality. However, evidence from device monitoring trials in particular might have been influenced by technology and design issues that might be rectified in future trials. Results from the literature suggest that the ideal HFDM plan would include outpatient follow-up at an HF specialty clinic and continuous education to improve patient self-care. The end result of this plan would lead to better understanding on the part of the patient and improved patient ability to recognize and respond to signs of decompensation.

  1. A modeling framework for system restoration from cascading failures.

    PubMed

    Liu, Chaoran; Li, Daqing; Zio, Enrico; Kang, Rui

    2014-01-01

    System restoration from cascading failures is an integral part of the overall defense against catastrophic breakdown in networked critical infrastructures. From the outbreak of cascading failures to the system complete breakdown, actions can be taken to prevent failure propagation through the entire network. While most analysis efforts have been carried out before or after cascading failures, restoration during cascading failures has been rarely studied. In this paper, we present a modeling framework to investigate the effects of in-process restoration, which depends strongly on the timing and strength of the restoration actions. Furthermore, in the model we also consider additional disturbances to the system due to restoration actions themselves. We demonstrate that the effect of restoration is also influenced by the combination of system loading level and restoration disturbance. Our modeling framework will help to provide insights on practical restoration from cascading failures and guide improvements of reliability and resilience of actual network systems.

  2. A Modeling Framework for System Restoration from Cascading Failures

    PubMed Central

    Liu, Chaoran; Li, Daqing; Zio, Enrico; Kang, Rui

    2014-01-01

    System restoration from cascading failures is an integral part of the overall defense against catastrophic breakdown in networked critical infrastructures. From the outbreak of cascading failures to the system complete breakdown, actions can be taken to prevent failure propagation through the entire network. While most analysis efforts have been carried out before or after cascading failures, restoration during cascading failures has been rarely studied. In this paper, we present a modeling framework to investigate the effects of in-process restoration, which depends strongly on the timing and strength of the restoration actions. Furthermore, in the model we also consider additional disturbances to the system due to restoration actions themselves. We demonstrate that the effect of restoration is also influenced by the combination of system loading level and restoration disturbance. Our modeling framework will help to provide insights on practical restoration from cascading failures and guide improvements of reliability and resilience of actual network systems. PMID:25474408

  3. The Effect of rFVIIa on Pro- and Anti-Inflamatory Cytokines in Serum and Cerebrospinal Fluid in a Swine Model of Traumatic Brain Injury

    DTIC Science & Technology

    2011-01-01

    alpha expression and protein levels after fluid percussion injury in rats: the effect of injury severity and brain temperature. Neurosurgery ...Short Communication The effect of rFVIIa on pro- and anti-inflamatory cytokines in serum and cerebrospinal fluid in a swine model of traumatic brain...Tumor necrosis factor-ex lnterleukin-1 p lnterleukin-1 0 rfVlla TBl Twenty anesthetized immature Yorkshire swine underwent fluid percussion TBI. At

  4. Network analysis of swine shipments in Ontario, Canada, to support disease spread modelling and risk-based disease management.

    PubMed

    Dorjee, S; Revie, C W; Poljak, Z; McNab, W B; Sanchez, J

    2013-10-01

    Understanding contact networks are important for modelling and managing the spread and control of communicable diseases in populations. This study characterizes the swine shipment network of a multi-site production system in southwestern Ontario, Canada. Data were extracted from a company's database listing swine shipments among 251 swine farms, including 20 sow, 69 nursery and 162 finishing farms, for the 2-year period of 2006 to 2007. Several network metrics were generated. The number of shipments per week between pairs of farms ranged from 1 to 6. The medians (and ranges) of out-degree were: sow 6 (1-21), nursery 8 (0-25), and finishing 0 (0-4), over the entire 2-year study period. Corresponding estimates for in-degree of nursery and finishing farms were 3 (0-9) and 3 (0-12) respectively. Outgoing and incoming infection chains (OIC and IIC), were also measured. The medians (ranges) of the monthly OIC and IIC were 0 (0-8) and 0 (0-6), respectively, with very similar measures observed for 2-week intervals. Nursery farms exhibited high measures of centrality. This indicates that they pose greater risks of disease spread in the network. Therefore, they should be given a high priority for disease prevention and control measures affecting all age groups alike. The network demonstrated scale-free and small-world topologies as observed in other livestock shipment studies. This heterogeneity in contacts among farm types and network topologies should be incorporated in simulation models to improve their validity. In conclusion, this study provided useful epidemiological information and parameters for the control and modelling of disease spread among swine farms, for the first time from Ontario, Canada.

  5. Two-parameter Failure Model Improves Time-independent and Time-dependent Failure Predictions

    SciTech Connect

    Huddleston, R L

    2004-01-27

    A new analytical model for predicting failure under a generalized, triaxial stress state was developed by the author and initially reported in 1984. The model was validated for predicting failure under elevated-temperature creep-rupture conditions. Biaxial data for three alloy steels, Types 304 and 316 stainless steels and Inconel 600, demonstrated two to three orders of magnitude reduction in the scatter of predicted versus observed creep-rupture times as compared to the classical failure models of Mises, Tresca, and Rankine. In 1990, the new model was incorporated into American Society of Mechanical Engineers (ASME) Code Case N47-29 for design of components operating under creep-rupture conditions. The current report provides additional validation of the model for predicting failure under time-independent conditions and also outlines a methodology for predicting failure under cyclic, time-dependent, creep-fatigue conditions. The later extension of the methodology may have the potential to improve failure predictions there as well. These results are relevant to most design applications, but they have special relevance to high-performance design applications such as components for high-pressure equipment, nuclear reactors, and jet engines.

  6. Modeling influenza epidemics and pandemics: insights into the future of swine flu (H1N1).

    PubMed

    Coburn, Brian J; Wagner, Bradley G; Blower, Sally

    2009-06-22

    Here we present a review of the literature of influenza modeling studies, and discuss how these models can provide insights into the future of the currently circulating novel strain of influenza A (H1N1), formerly known as swine flu. We discuss how the feasibility of controlling an epidemic critically depends on the value of the Basic Reproduction Number (R0). The R0 for novel influenza A (H1N1) has recently been estimated to be between 1.4 and 1.6. This value is below values of R0 estimated for the 1918-1919 pandemic strain (mean R0 approximately 2: range 1.4 to 2.8) and is comparable to R0 values estimated for seasonal strains of influenza (mean R0 1.3: range 0.9 to 2.1). By reviewing results from previous modeling studies we conclude it is theoretically possible that a pandemic of H1N1 could be contained. However it may not be feasible, even in resource-rich countries, to achieve the necessary levels of vaccination and treatment for control. As a recent modeling study has shown, a global cooperative strategy will be essential in order to control a pandemic. This strategy will require resource-rich countries to share their vaccines and antivirals with resource-constrained and resource-poor countries. We conclude our review by discussing the necessity of developing new biologically complex models. We suggest that these models should simultaneously track the transmission dynamics of multiple strains of influenza in bird, pig and human populations. Such models could be critical for identifying effective new interventions, and informing pandemic preparedness planning. Finally, we show that by modeling cross-species transmission it may be possible to predict the emergence of pandemic strains of influenza.

  7. An Effective and Reproducible Model of Ventricular Fibrillation in Crossbred Yorkshire Swine (Sus scrofa) for Use in Physiologic Research.

    PubMed

    Burgert, James M; Johnson, Arthur D; Garcia-Blanco, Jose C; Craig, W John; O'Sullivan, Joseph C

    2015-10-01

    Transcutaneous electrical induction (TCEI) has been used to induce ventricular fibrillation (VF) in laboratory swine for physiologic and resuscitation research. Many studies do not describe the method of TCEI in detail, thus making replication by future investigators difficult. Here we describe a detailed method of electrically inducing VF that was used successfully in a prospective, experimental resuscitation study. Specifically, an electrical current was passed through the heart to induce VF in crossbred Yorkshire swine (n = 30); the current was generated by using two 22-gauge spinal needles, with one placed above and one below the heart, and three 9V batteries connected in series. VF developed in 28 of the 30 pigs (93%) within 10 s of beginning the procedure. In the remaining 2 swine, VF was induced successfully after medial redirection of the superior parasternal needle. The TCEI method is simple, reproducible, and cost-effective. TCEI may be especially valuable to researchers with limited access to funding, sophisticated equipment, or colleagues experienced in interventional cardiology techniques. The TCEI method might be most appropriate for pharmacologic studies requiring VF, VF resulting from the R-on-T phenomenon (as in prolonged QT syndrome), and VF arising from other ectopic or reentrant causes. However, the TCEI method does not accurately model the most common cause of VF, acute coronary occlusive disease. Researchers must consider the limitations of TCEI that may affect internal and external validity of collected data, when designing experiments using this model of VF.

  8. Quantification of morphologic, cytologic, and kinetic parameters of unirradiated swine skin: a histologic model

    SciTech Connect

    Archambeau, J.O.; Bennett, G.W.

    1984-05-01

    This study determines multiple histologic and cell kinetic parameters of unirradiated swine skin. The prickle cell layer exists as a shell three to six cells thick. The proliferative basal layer exists as a confluent monolayer with 2031 +/- 48 cells/cm; it has delta growth fraction of 1, an average cell generation time of 12 days, a T/sub s/ of 9 hr, and a T/sub s/ + T/sub G2/ + T/sub 1/2M/ of 17 to 19 hr. The labeling index is 3.9% with a diurnal variation having a 5% peak at 1800 hr and a 2.5% nadir at 0900-1100 hr. The mitotic index varies from 1.7 to 3.2% and has no clear-cut diurnal variation. These values are similar to those available for man. These data and those published previously are utilized to define a histologic model of the irradiated epidermal cell renewal system. These measured values are compared with those derived from analysis of available time-dose isoeffect data using a single-hit multitarget and a linear-quadratic model.

  9. A Comparison of Proximal Tibia and Proximal Humerus Infusion Rates of Plasma Under High Pressure Using the EZ IO Intraosseous Device in the Adult Swine (Sus scrofa) Hypovolemic Model

    DTIC Science & Technology

    2013-01-10

    plasma under high pressure using the EZ IO intraosseous device in the adult swine (Sus scrofa ) hypovolemic model. FWH20100171A FWH20100171ALairet...resuscitation, swine, sus scrofa U U U SAR Vikhyat Bebarta, MD 210-275-3794 WHASC- Animal Final Report 170ct2012 1. Protocol Number: FWH20100171A 2...the EZ 10 intraosseous device in the adult swine (Sus scrofa ) hypovolemic model. 4. Principal Investigator PI): Name Rank Date of Branch Staff

  10. Catheter‐based induction of renal ischemia/reperfusion in swine: description of an experimental model

    PubMed Central

    Malagrino, Pamella A.; Venturini, Gabriela; Yogi, Patrícia S.; Dariolli, Rafael; Padilha, Kallyandra; Kiers, Bianca; Gois, Tamiris C.; da Motta‐Leal‐Filho, Joaquim M.; Takimura, Celso K.; Girardi, Adriana C. C.; Carnevale, Francisco C.; Zeri, Ana C. M.; Malheiros, Denise M. A. C.; Krieger, José E.; Pereira, Alexandre C.

    2014-01-01

    Abstract Several techniques to induce renal ischemia have been proposed: clamp, PVA particles, and catheter‐balloon. We report the development of a controlled, single‐insult model of unilateral renal ischemia/reperfusion (I/R) without contralateral nephrectomy, using a suitable model, the pig. This is a balloon‐catheter‐based model using a percutaneous, interventional radiology procedure. One angioplasty balloon‐catheter was placed into the right renal artery and inflated for 120 min and reperfusion over 24 h. Serial serums were sampled from the inferior vena cava and urine was directly sampled from the bladder throughout the experiment, and both kidneys were excised after 24 h of reperfusion. Analyses of renal structure and function were performed by hematoxylin–eosin/periodic Acid‐Schiff, serum creatinine (SCr), blood urea nitrogen (BUN), fractional excretion of ions, and glucose, SDS‐PAGE analysis of urinary proteins, and serum neutrophil gelatinase‐associated lipocalin (NGAL). Total nitrated protein was quantified to characterize oxidative stress. Acute tubular necrosis (ATN) was identified in every animal, but only two animals showed levels of SCr above 150% of baseline values. As expected, I/R increased SCr and BUN. Fractional sodium, potassium, chloride, and bicarbonate excretion were modulated during ischemia. Serum‐nitrated proteins and NGAL had two profiles: decreased with ischemia and increased after reperfusion. This decline was associated with increased protein excretion during ischemia and early reperfusion. Altogether, these data show that the renal I/R model can be performed by percutaneous approach in the swine model. This is a suitable translational model to study new early renal ischemic biomarkers and pathophysiological mechanisms in renal ischemia. PMID:25263203

  11. Early Cellular Changes in the Ascending Aorta and Myocardium in a Swine Model of Metabolic Syndrome

    PubMed Central

    Mahmood, Feroze; Owais, Khurram; Bardia, Amit; Khabbaz, Kamal R.; Liu, David; Senthilnathan, Venkatachalam; Lassaletta, Antonio D.; Sellke, Frank; Matyal, Robina

    2016-01-01

    Background Metabolic syndrome is associated with pathological remodeling of the heart and adjacent vessels. The early biochemical and cellular changes underlying the vascular damage are not fully understood. In this study, we sought to establish the nature, extent, and initial timeline of cytochemical derangements underlying reduced ventriculo-arterial compliance in a swine model of metabolic syndrome. Methods Yorkshire swine (n = 8 per group) were fed a normal diet (ND) or a high-cholesterol (HCD) for 12 weeks. Myocardial function and blood flow was assessed before harvesting the heart. Immuno-blotting and immuno-histochemical staining were used to assess the cellular changes in the myocardium, ascending aorta and left anterior descending artery (LAD). Results There was significant increase in body mass index, blood glucose and mean arterial pressures (p = 0.002, p = 0.001 and p = 0.024 respectively) in HCD group. At the cellular level there was significant increase in anti-apoptotic factors p-Akt (p = 0.007 and p = 0.002) and Bcl-xL (p = 0.05 and p = 0.01) in the HCD aorta and myocardium, respectively. Pro-fibrotic markers TGF-β (p = 0.01), pSmad1/5 (p = 0.03) and MMP-9 (p = 0.005) were significantly increased in the HCD aorta. The levels of pro-apoptotic p38MAPK, Apaf-1 and cleaved Caspase3 were significantly increased in aorta of HCD (p = 0.03, p = 0.04 and p = 0.007 respectively). Similar changes in coronary arteries were not observed in either group. Functionally, the high cholesterol diet resulted in significant increase in ventricular end systolic pressure and–dp/dt (p = 0.05 and p = 0.007 respectively) in the HCD group. Conclusion Preclinical metabolic syndrome initiates pro-apoptosis and pro-fibrosis pathways in the heart and ascending aorta, while sparing coronary arteries at this early stage of dietary modification. PMID:26766185

  12. In Vivo Validation of Predicted and Conserved T Cell Epitopes in a Swine Influenza Model

    PubMed Central

    Gutiérrez, Andres H.; Loving, Crystal; Moise, Leonard; Terry, Frances E.; Brockmeier, Susan L.; Hughes, Holly R.; Martin, William D.; De Groot, Anne S.

    2016-01-01

    Swine influenza is a highly contagious respiratory viral infection in pigs that is responsible for significant financial losses to pig farmers annually. Current measures to protect herds from infection include: inactivated whole-virus vaccines, subunit vaccines, and alpha replicon-based vaccines. As is true for influenza vaccines for humans, these strategies do not provide broad protection against the diverse strains of influenza A virus (IAV) currently circulating in U.S. swine. Improved approaches to developing swine influenza vaccines are needed. Here, we used immunoinformatics tools to identify class I and II T cell epitopes highly conserved in seven representative strains of IAV in U.S. swine and predicted to bind to Swine Leukocyte Antigen (SLA) alleles prevalent in commercial swine. Epitope-specific interferon-gamma (IFNγ) recall responses to pooled peptides and whole virus were detected in pigs immunized with multi-epitope plasmid DNA vaccines encoding strings of class I and II putative epitopes. In a retrospective analysis of the IFNγ responses to individual peptides compared to predictions specific to the SLA alleles of cohort pigs, we evaluated the predictive performance of PigMatrix and demonstrated its ability to distinguish non-immunogenic from immunogenic peptides and to identify promiscuous class II epitopes. Overall, this study confirms the capacity of PigMatrix to predict immunogenic T cell epitopes and demonstrate its potential for use in the design of epitope-driven vaccines for swine. Additional studies that match the SLA haplotype of animals with the study epitopes will be required to evaluate the degree of immune protection conferred by epitope-driven DNA vaccines in pigs. PMID:27411061

  13. A Mathematical Model that Simulates Control Options for African Swine Fever Virus (ASFV)

    PubMed Central

    Barongo, Mike B.; Bishop, Richard P; Fèvre, Eric M; Knobel, Darryn L; Ssematimba, Amos

    2016-01-01

    A stochastic model designed to simulate transmission dynamics of African swine fever virus (ASFV) in a free-ranging pig population under various intervention scenarios is presented. The model was used to assess the relative impact of the timing of the implementation of different control strategies on disease-related mortality. The implementation of biosecurity measures was simulated through incorporation of a decay function on the transmission rate. The model predicts that biosecurity measures implemented within 14 days of the onset of an epidemic can avert up to 74% of pig deaths due to ASF while hypothetical vaccines that confer 70% immunity when deployed prior to day 14 of the epidemic could avert 65% of pig deaths. When the two control measures are combined, the model predicts that 91% of the pigs that would have otherwise succumbed to the disease if no intervention was implemented would be saved. However, if the combined interventions are delayed (defined as implementation from > 60 days) only 30% of ASF-related deaths would be averted. In the absence of vaccines against ASF, we recommend early implementation of enhanced biosecurity measures. Active surveillance and use of pen-side diagnostic assays, preferably linked to rapid dissemination of this data to veterinary authorities through mobile phone technology platforms are essential for rapid detection and confirmation of ASF outbreaks. This prediction, although it may seem intuitive, rationally confirms the importance of early intervention in managing ASF epidemics. The modelling approach is particularly valuable in that it determines an optimal timing for implementation of interventions in controlling ASF outbreaks. PMID:27391689

  14. A Mathematical Model that Simulates Control Options for African Swine Fever Virus (ASFV).

    PubMed

    Barongo, Mike B; Bishop, Richard P; Fèvre, Eric M; Knobel, Darryn L; Ssematimba, Amos

    2016-01-01

    A stochastic model designed to simulate transmission dynamics of African swine fever virus (ASFV) in a free-ranging pig population under various intervention scenarios is presented. The model was used to assess the relative impact of the timing of the implementation of different control strategies on disease-related mortality. The implementation of biosecurity measures was simulated through incorporation of a decay function on the transmission rate. The model predicts that biosecurity measures implemented within 14 days of the onset of an epidemic can avert up to 74% of pig deaths due to ASF while hypothetical vaccines that confer 70% immunity when deployed prior to day 14 of the epidemic could avert 65% of pig deaths. When the two control measures are combined, the model predicts that 91% of the pigs that would have otherwise succumbed to the disease if no intervention was implemented would be saved. However, if the combined interventions are delayed (defined as implementation from > 60 days) only 30% of ASF-related deaths would be averted. In the absence of vaccines against ASF, we recommend early implementation of enhanced biosecurity measures. Active surveillance and use of pen-side diagnostic assays, preferably linked to rapid dissemination of this data to veterinary authorities through mobile phone technology platforms are essential for rapid detection and confirmation of ASF outbreaks. This prediction, although it may seem intuitive, rationally confirms the importance of early intervention in managing ASF epidemics. The modelling approach is particularly valuable in that it determines an optimal timing for implementation of interventions in controlling ASF outbreaks.

  15. Pulmonary deposition of aerosolized Bacillus atrophaeus in a Swine model due to exposure from a simulated anthrax letter incident.

    PubMed

    Duncan, E J Scott; Kournikakis, Bill; Ho, Jim; Hill, Ira

    2009-02-01

    Dry anthrax spore powder is readily disseminated as an aerosol and it is possible that passive dispersion when opening a letter containing anthrax spores may result in lethal doses to humans. The specific aim of this study was to quantify the respirable aerosol hazard associated with opening an envelope/letter contaminated with a dry spore powder of the biological pathogen anthrax in a typical office environment. An envelope containing a letter contaminated with 1.0 g of dry Bacillus atrophaeus (BG) spores (pathogen simulant) was opened in the presence of an unrestrained swine model. Aerosolized spores were detected in the room in seconds and peak concentrations occurred by three minutes. The swine, located approximately 1.5 m from the source, was exposed to the aerosol for 28 min following the letter opening event and then moved to a clean room for 30 min. A necropsy was completed to determine the extent of in vivo spore deposition in the lungs. The median number of viable colony forming units (CFU) measured in the combined right and left lung was 21,200: the average mass of both lungs was 283 g. In excess of 100 CFU per gram of lung tissue was found at sites within the anterior, intermediate and posterior lobes. The results of this study confirmed that opening an envelope containing spores generated an aerosol spanning the respirable particle size range of 1-10 microm, and that normal respiration of swine led to spore deposition throughout the lungs. The observed deposition of spores in the lungs of the swine is within the LD(50) range of 2,500-55,000 estimated for humans for inhaled anthrax. Thus, there would appear to be a significant health risk to those individuals exposed to anthrax spores when opening a contaminated envelope.

  16. Short-Term Effects of Ketamine and Isoflurane on Left Ventricular Ejection Fraction in an Experimental Swine Model

    PubMed Central

    Wessler, Benjamin; Madias, Christopher; Pandian, Natesa; Link, Mark S.

    2011-01-01

    Background. General anesthesia is an essential element of experimental medical procedures. Ketamine and isoflurane are agents commonly used to induce and maintain anesthesia in animals. The cardiovascular effects of these anesthetic agents are diverse, and the response of global myocardial function is unknown. Methods. In a series of 15 swine, echocardiography measurements of left ventricular ejection fraction (LVEF) were obtained before the animals received anesthesia (baseline), after an intramuscular injection of ketamine (postketamine) and after inhaled isoflurane (postisoflurane). Results. The mean LVEF of an unanesthetized swine was 47 ± 3%. There was a significant decrease in the mean LVEF after administration of ketamine to 41 + 6.5% (P = 0.003). The addition of inhaled isoflurane did not result in further decrease in mean LVEF (mean LVEF 38 ± 7.2%, P = 0.22). Eight of the swine had an increase in their LVEF with sympathetic stimulation. Conclusions. In our experimental model the administration of ketamine was associated with decreased LV function. The decrease may be largely secondary to a blunting of sympathetic tone. The addition of isoflurane to ketamine did not significantly change LV function. A significant number of animals had returned to preanesthesia LV function with sympathetic stimulation. PMID:22347646

  17. Comparison of Two Foreign Body Retrieval Devices with Adjustable Loops in a Swine Model

    SciTech Connect

    Konya, Andras

    2006-12-15

    The purpose of the study was to compare two similar foreign body retrieval devices, the Texan{sup TM} (TX) and the Texan LONGhorn{sup TM} (TX-LG), in a swine model. Both devices feature a {<=}30-mm adjustable loop. Capture times and total procedure times for retrieving foreign bodies from the infrarenal aorta, inferior vena cava, and stomach were compared. All attempts with both devices (TX, n = 15; TX-LG, n = 14) were successful. Foreign bodies in the vasculature were captured quickly using both devices (mean {+-} SD, 88 {+-} 106 sec for TX vs 67 {+-} 42 sec for TX-LG) with no significant difference between them. The TX-LG, however, allowed significantly better capture times than the TX in the stomach (p = 0.022), Overall, capture times for the TX-LG were significantly better than for the TX (p = 0.029). There was no significant difference between the total procedure times in any anatomic region. TX-LG performed significantly better than the TX in the stomach and therefore overall. The better torque control and maneuverability of TX-LG resulted in better performance in large anatomic spaces.

  18. The potential of antiviral agents to control classical swine fever: a modelling study.

    PubMed

    Backer, Jantien A; Vrancken, Robert; Neyts, Johan; Goris, Nesya

    2013-09-01

    Classical swine fever (CSF) represents a continuous threat to pig populations that are free of disease without vaccination. When CSF virus is introduced, the minimal control strategy imposed by the EU is often insufficient to mitigate the epidemic. Additional measures such as preemptive culling encounter ethical objections, whereas emergency vaccination leads to prolonged export restrictions. Antiviral agents, however, provide instantaneous protection without inducing an antibody response. The use of antiviral agents to contain CSF epidemics is studied with a model describing within- and between-herd virus transmission. Epidemics are simulated in a densely populated livestock area in The Netherlands, with farms of varying sizes and pig types (finishers, piglets and sows). Our results show that vaccination and/or antiviral treatment in a 2 km radius around an infected herd is more effective than preemptive culling in a 1 km radius. However, the instantaneous but temporary protection provided by antiviral treatment is slightly less effective than the delayed but long-lasting protection offered by vaccination. Therefore, the most effective control strategy is to vaccinate animals when allowed (finishers and piglets) and to treat with antiviral agents when vaccination is prohibited (sows). As independent control measure, antiviral treatment in a 1 km radius presents an elevated risk of epidemics running out of control. A 2 km control radius largely eliminates this risk.

  19. Assessment of Deep Partial Thickness Burn Treatment with Keratin Biomaterial Hydrogels in a Swine Model

    PubMed Central

    Poranki, D.; Goodwin, C.

    2016-01-01

    Partial thickness burns can advance to full thickness after initial injury due to inadequate tissue perfusion and increased production of inflammatory cytokines, which has been referred to as burn wound progression. In previous work, we demonstrated that a keratin biomaterial hydrogel appeared to reduce burn wound progression. In the present study, we tested the hypothesis that a modified keratin hydrogel could reduce burn wound progression and speed healing. Standardized burn wounds were created in Yorkshire swine and treated within 30 minutes with keratin hydrogel (modified and unmodified), collagen hydrogel, or silver sulfadiazine (SSD). Digital images of each wound were taken for area measurements immediately prior to cleaning and dressing changes. Wound tissue was collected and assessed histologically at several time points. Wound area showed a significant difference between hydrogels and SSD groups, and rates of reepithelialization at early time points showed an increase when keratin treatment was used compared to both collagen and SSD. A linear regression model predicted a time to wound closure of approximately 25 days for keratin hydrogel while SSD treatment required 35 days. There appeared to be no measurable differences between the modified and unmodified formulations of keratin hydrogels. PMID:28025638

  20. One-Health Simulation Modelling: Assessment of Control Strategies Against the Spread of Influenza between Swine and Human Populations Using NAADSM.

    PubMed

    Dorjee, S; Revie, C W; Poljak, Z; McNab, W B; McClure, J T; Sanchez, J

    2016-04-01

    Simulation models implemented using a range of parameters offer a useful approach to identifying effective disease intervention strategies. The objective of this study was to investigate the effects of key control strategies to mitigate the simultaneous spread of influenza among and between swine and human populations. We used the pandemic H1N1 2009 virus as a case study. The study population included swine herds (488 herds) and households-of-people (29,707 households) within a county in Ontario, Canada. Households were categorized as: (i) rural households with swine workers, (ii) rural households without swine workers and (iii) urban households without swine workers. Seventy-two scenarios were investigated based on a combination of the parameters of speed of detection and control strategies, such as quarantine strategy, effectiveness of movement restriction and ring vaccination strategy, all assessed at three levels of transmissibility of the virus at the swine-human interface. Results showed that the speed of detection of the infected units combined with the quarantine strategy had the largest impact on the duration and size of outbreaks. A combination of fast to moderate speed of the detection (where infected units were detected within 5-10 days since first infection) and quarantine of the detected units alone contained the outbreak within the swine population in most of the simulated outbreaks. Ring vaccination had no added beneficial effect. In conclusion, our study suggests that the early detection (and therefore effective surveillance) and effective quarantine had the largest impact in the control of the influenza spread, consistent with earlier studies. To our knowledge, no study had previously assessed the impact of the combination of different intervention strategies involving the simultaneous spread of influenza between swine and human populations.

  1. Swine Dysentery.

    PubMed

    Burrough, E R

    2017-01-01

    Swine dysentery is a severe enteric disease in pigs, which is characterized by bloody to mucoid diarrhea and associated with reduced growth performance and variable mortality. This disease is most often observed in grower-finisher pigs, wherein susceptible pigs develop a significant mucohemorrhagic typhlocolitis following infection with strongly hemolytic spirochetes of the genus Brachyspira. While swine dysentery is endemic in many parts of the world, the disease had essentially disappeared in much of the United States by the mid-1990s as a result of industry consolidation and effective treatment, control, and elimination methods. However, since 2007, there has been a reported increase in laboratory diagnosis of swine dysentery in parts of North America along with the detection of novel pathogenic Brachyspira spp worldwide. Accordingly, there has been a renewed interest in swine dysentery and Brachyspira spp infections in pigs, particularly in areas where the disease was previously eliminated. This review provides an overview of knowledge on the etiology, pathogenesis, and diagnosis of swine dysentery, with insights into risk factors and control.

  2. Stochastic load-redistribution model for cascading failure propagation.

    PubMed

    Lehmann, Jörg; Bernasconi, Jakob

    2010-03-01

    A class of probabilistic models for cascading failure propagation in interconnected systems is proposed. The models are able to represent important physical characteristics of realistic load-redistribution mechanisms, e.g., that the load increments after a failure depend on the load of the failing element and that they may be distributed nonuniformly among the remaining elements. In the limit of large system sizes, the models are solved analytically in terms of generalized branching processes, and the failure propagation properties of a prototype example are analyzed in detail.

  3. Experimental models of hepatotoxicity related to acute liver failure

    PubMed Central

    Maes, Michaël; Vinken, Mathieu; Jaeschke, Hartmut

    2015-01-01

    Acute liver failure can be the consequence of various etiologies, with most cases arising from drug-induced hepatotoxicity in Western countries. Despite advances in this field, the management of acute liver failure continues to be one of the most challenging problems in clinical medicine. The availability of adequate experimental models is of crucial importance to provide a better understanding of this condition and to allow identification of novel drug targets, testing the efficacy of new therapeutic interventions and acting as models for assessing mechanisms of toxicity. Experimental models of hepatotoxicity related to acute liver failure rely on surgical procedures, chemical exposure or viral infection. Each of these models has a number of strengths and weaknesses. This paper specifically reviews commonly used chemical in vivo and in vitro models of hepatotoxicity associated with acute liver failure. PMID:26631581

  4. Computational Failure Modeling of Lower Extremities

    DTIC Science & Technology

    2012-01-01

    bone fracture, ligament tear, and muscle rupture. While these injuries may seem well-defined through medical imaging, the process of injury and the... process of high strain rate direct axial loading that leads to bone fracture and fragmentation is investigated. 15. SUBJECT TERMS failure, lower...While these injuries may seem well-defined through medical imaging, the process of injury and the effects of vehicle system design to protection are

  5. A Modified Heterotopic Swine Hind Limb Transplant Model for Translational Vascularized Composite Allotransplantation (VCA) Research

    PubMed Central

    Ibrahim, Zuhaib; Cooney, Damon S.; Shores, Jaimie T.; Sacks, Justin M.; Wimmers, Eric G.; Bonawitz, Steven C.; Gordon, Chad; Ruben, Dawn; Schneeberger, Stefan; Lee, W. P. Andrew; Brandacher, Gerald

    2013-01-01

    Vascularized Composite Allotransplantation (VCA) such as hand and face transplants represent a viable treatment option for complex musculoskeletal trauma and devastating tissue loss. Despite favorable and highly encouraging early and intermediate functional outcomes, rejection of the highly immunogenic skin component of a VCA and potential adverse effects of chronic multi-drug immunosuppression continue to hamper widespread clinical application of VCA. Therefore, research in this novel field needs to focus on translational studies related to unique immunologic features of VCA and to develop novel immunomodulatory strategies for immunomodulation and tolerance induction following VCA without the need for long term immunosuppression. This article describes a reliable and reproducible translational large animal model of VCA that is comprised of an osteomyocutaneous flap in a MHC-defined swine heterotopic hind limb allotransplantation. Briefly, a well-vascularized skin paddle is identified in the anteromedial thigh region using near infrared laser angiography. The underlying muscles, knee joint, distal femur, and proximal tibia are harvested on a femoral vascular pedicle. This allograft can be considered both a VCA and a vascularized bone marrow transplant with its unique immune privileged features. The graft is transplanted to a subcutaneous abdominal pocket in the recipient animal with a skin component exteriorized to the dorsolateral region for immune monitoring. Three surgical teams work simultaneously in a well-coordinated manner to reduce anesthesia and ischemia times, thereby improving efficiency of this model and reducing potential confounders in experimental protocols. This model serves as the groundwork for future therapeutic strategies aimed at reducing and potentially eliminating the need for chronic multi-drug immunosuppression in VCA. PMID:24145603

  6. The Adult Göttingen Minipig as a Model for Chronic Heart Failure After Myocardial Infarction: Focus on Cardiovascular Imaging and Regenerative Therapies

    PubMed Central

    Schuleri, Karl H; Boyle, Andrew J; Centola, Marco; Amado, Luciano C; Evers, Robert; Zimmet, Jeffrey M; Evers, Kristine S; Ostbye, Katherine M; Scorpio, Diana G; Hare, Joshua M; Lardo, Albert C

    2008-01-01

    Porcine models have become increasingly popular in cardiovascular research. The standard farm pig rapidly increases in body weight and size, potentially confounding serial measurements of cardiac function and morphology. We developed an adult porcine model that does not show physiologic increases in heart mass during the study period and is suitable for long-term study. We compared adult minipigs with the commonly used adolescent Yorkshire swine. Myocardial infarction was induced in adult Göttingen minipigs and adolescent Yorkshire swine by occlusion of the left anterior descending coronary artery followed by reperfusion. At 8 wk after infarction, the left ventricular ejection fraction was 34.1 ± 2.3% in minipigs and 30.7 ± 2.0% in Yorkshire swine. The left ventricular end-diastolic mass in Yorkshire pigs assessed by magnetic resonance imaging increased 17 ± 5 g, from 42.6 ± 4.3 g at week 1 after infarction to 52.8 ± 6.6 g at week 8, whereas it remained unchanged in minipigs. Cardiac anatomy and physiology in adult minipigs were evaluated invasively by angiography and noninvasively by Multidetector Computed Tomography and by Magnetic Resonance Imaging at 1.5 T and 3 T prior to myocardial infarction and during folow-up. This porcine heart failure model is reproducible, mimics the pathophysiology in patients who have experienced myocardial infarction, and is suitable for imaging studies. New heart failure therapies and devices can be tested preclinically in this adult animal model of chronic heart failure. PMID:19149414

  7. UM206, a selective Frizzled antagonist, attenuates adverse remodeling after myocardial infarction in swine.

    PubMed

    Uitterdijk, André; Hermans, Kevin C M; de Wijs-Meijler, Daphne P M; Daskalopoulos, Evangelos P; Reiss, Irwin K; Duncker, Dirk J; Matthijs Blankesteijn, W; Merkus, Daphne

    2016-02-01

    Modulation of Wnt/Frizzled signaling with UM206 reduced infarct expansion and prevented heart failure development in mice, an effect that was accompanied by increased myofibroblast presence in the infarct, suggesting that Wnt/Frizzled signaling has a key role in cardiac remodeling following myocardial infarction (MI). This study investigated the effects of modulation of Wnt/Frizzled signaling with UM206 in a swine model of reperfused MI. For this purpose, seven swine with MI were treated with continuous infusion of UM206 for 5 weeks. Six control swine were treated with vehicle. Another eight swine were sham-operated. Cardiac function was determined by echo in awake swine. Infarct mass was estimated at baseline by heart-specific fatty acid-binding protein ELISA and at follow-up using planimetry. Components of Wnt/Frizzled signaling, myofibroblast presence, and extracellular matrix were measured at follow-up with qPCR and/or histology. Results show that UM206 treatment resulted in a significant decrease in infarct mass compared with baseline (-41±10%), whereas infarct mass remained stable in the Control-MI group (+3±17%). Progressive dilation of the left ventricle occurred in the Control-MI group between 3 and 5 weeks after MI, while adverse remodeling was halted in the UM206-treated group. mRNA expression for Frizzled-4 and the Frizzled co-receptor LRP5 was increased in UM206-treated swine as compared with Control-MI swine. Myofibroblast presence was significantly lower in infarcted tissue of the UM206-treated animals (1.53±0.43% vs 3.38±0.61%) at 5 weeks follow-up. This study demonstrates that UM206 treatment attenuates adverse remodeling in a swine model of reperfused MI, indicating that Wnt/Frizzled signaling is a promising target to improve infarct healing and limit post-MI remodeling.

  8. Swine Model of Thrombotic Caval Occlusion Created by Autologous Thrombus Injection with Assistance of Intra-caval Net Knitting

    PubMed Central

    Shi, Wan-Yin; Wu, Shuang; Hu, Lan-Yue; Liu, Chang-Jian; Gu, Jian-Ping

    2015-01-01

    To evaluate the feasibility of a swine model of thrombotic inferior vena cava (IVC) occlusion (IVCO) created by autologous thrombus injection with assistance of intra-caval net knitting. Sixteen pigs were included and divided into two groups: Group A (n = 10), IVCO model created by knitting a caval net followed by autologous thrombus injection; Group B (n = 6), control model created by knitting a net and normal saline injection. Venography was performed to assess each model and the associated thrombotic occlusion. The vessels were examined histologically to analyse the pathological changes postoperatively. IVCO model was successfully created in 10 animals in Group A (100%). Immediate venography showed extensive clot burden in the IVC. Postoperative venography revealed partial caval occlusion at 7 days, and complete occlusion coupled with collateral vessels at 14 days. Histologically, Group A animals had significantly greater venous wall thickening, with CD163-positive and CD3-positive cell infiltration. Recanalization channels were observed at the margins of the thrombus. By contrast, no thrombotic occlusion of the IVC was observed in Group B. The thrombotic IVCO model can be reliably established in swine. The inflammatory reaction may contribute to the caval thrombus propagation following occlusion. PMID:26680253

  9. Differences in Pathogenesis for Salmonella enterica serovar Typhimurium in the Mouse Versus the Swine Model Identify Bacterial Gene Products Required for Systemic but not Gastrointestinal Disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over the last several decades, the mouse model of Typhoid fever has been an extremely productive model to investigate Salmonella enterica serovar Typhimurium pathogenesis. The mouse is the paradigm for investigating systemic disease due to infection by Salmonella; however, the swine model of gastro...

  10. Heat flux measurements and modeling of malodorous compounds above an anaerobic swine lagoon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The concentration of p-cresol and p-ethylphenol, two malodorants typical of swine waste, were measured at 0.5 m and 1.5 m above a waste treatment lagoon during two separate campaigns encompassing late winter through early spring and late spring through early summer. Concomitant collection of air te...

  11. In vivo validation of predicted and conserved T cell epitopes in a swine influenza model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Swine influenza is a highly contagious respiratory viral infection in pigs that is responsible for significant financial losses to pig farmers annually. Current measures to protect herds from infection using inactivated whole-virus, subunit and alpha replicon-based vaccines do not provide broad prot...

  12. Immune response phenotype of allergic versus clinically tolerant pigs in a neonatal swine model of allergy.

    PubMed

    Schmied, Julie; Rupa, Prithy; Garvie, Sarah; Wilkie, Bruce

    2013-07-15

    The prevalence of childhood food allergy and the duration of these allergies, particularly those considered to be transient, like egg and milk allergy, are increasing. The identification of allergic individuals using minimally invasive, non-anaphylaxis-threatening methods is therefore of increasing importance. In this experiment, correlates were sought of an allergic immune response (IR) phenotype in pigs. Using pigs pre-treated with heat-killed bacteria or bacterial components before allergic sensitization with the egg white protein ovomucoid (Ovm), differences were determined in IR phenotype of pigs in the categories treated-allergic, treated-tolerant, control-allergic (CA) and control-tolerant. Phenotype was established by measuring immunoglobulin (Ig)-associated antibody activity (AbA), cytokine profiles and the proportion of blood T-regulatory cells (T-regs) and observing late-phase allergen-specific skin tests (ST). Although 100% of pigs became sensitized to Ovm, only 33% of pigs had clinical signs of allergy after oral challenge with egg white. Pigs without clinical signs were classified as clinically tolerant. Sixty-seven percent of allergic pigs had a positive, late-phase ST classified as very strong or strong, while 84% of clinically tolerant pigs did not have late-phase ST. Treated-allergic pigs and CA pigs had greater total antibody IgG (H+L), IgE and IgG1 AbA than clinically tolerant pigs. Cytokine profiles of allergic pigs and the proportion of circulating T-regs, did not differ significantly between allergic and clinically tolerant pigs. Therefore, measurement of allergen-specific IgG, IgG1 and/or IgE activity and evaluation of late-phase ID ST may be useful in identifying allergic IR phenotypes in swine models of food allergy, which may be extended toward human use.

  13. A modified collagen gel enhances healing outcome in a preclinical swine model of excisional wounds.

    PubMed

    Elgharably, Haytham; Roy, Sashwati; Khanna, Savita; Abas, Motaz; Dasghatak, Piya; Das, Amitava; Mohammed, Kareem; Sen, Chandan K

    2013-01-01

    Collagen-based dressings are of great interest in wound care. However, evidence supporting their mechanism of action is scanty. This work provides first results from a preclinical swine model of excisional wounds, elucidating the mechanism of action of a modified collagen gel (MCG) dressing. Following wounding, wound-edge tissue was collected at specific time intervals (3, 7, 14, and 21 days postwounding). On day 7, histological analysis showed significant increase in the length of rete ridges, suggesting improved biomechanical properties of the healing wound tissue. Rapid and transient mounting of inflammation is necessary for efficient healing. MCG significantly accelerated neutrophil and macrophage recruitment to the wound site on day 3 and day 7 with successful resolution of inflammation on day 21. MCG induced monocyte chemotactic protein-1 expression in neutrophil-like human promyelocytic leukemia-60 cells in vitro. In vivo, MCG-treated wound tissue displayed elevated vascular endothelial growth factor expression. Consistently, MCG-treated wounds displayed significantly higher abundance of endothelial cells with increased blood flow to the wound area indicating improved vascularization. This observation was explained by the finding that MCG enhanced proliferation of wound-site endothelial cells. In MCG-treated wound tissue, Masson's trichrome and picrosirius red staining showed higher abundance of collagen and increased collagen type I:III ratio. This work presents first evidence from a preclinical setting explaining how a collagen-based dressing may improve wound closure by targeting multiple key mechanisms. The current findings warrant additional studies to determine whether the responses to the MCG are different from other collagen-based products used in clinical setting.

  14. A modified collagen gel dressing promotes angiogenesis in a preclinical swine model of chronic ischemic wounds.

    PubMed

    Elgharably, Haytham; Ganesh, Kasturi; Dickerson, Jennifer; Khanna, Savita; Abas, Motaz; Ghatak, Piya Das; Dixit, Sriteja; Bergdall, Valerie; Roy, Sashwati; Sen, Chandan K

    2014-01-01

    We recently performed proteomic characterization of a modified collagen gel (MCG) dressing and reported promising effects of the gel in healing full-thickness excisional wounds. In this work, we test the translational relevance of our aforesaid findings by testing the dressing in a swine model of chronic ischemic wounds recently reported by our laboratory. Full-thickness excisional wounds were established in the center of bipedicle ischemic skin flaps on the backs of animals. Ischemia was verified by laser Doppler imaging, and MCG was applied to the test group of wounds. Seven days post wounding, macrophage recruitment to the wound was significantly higher in MCG-treated ischemic wounds. In vitro, MCG up-regulated expression of Mrc-1 (a reparative M2 macrophage marker) and induced the expression of anti-inflammatory cytokine interleukin (IL)-10 and of fibroblast growth factor-basic (β-FGF). An increased expression of CCR2, an M2 macrophage marker, was noted in the macrophages from MCG treated wounds. Furthermore, analyses of wound tissues 7 days post wounding showed up-regulation of transforming growth factor-β, vascular endothelial growth factor, von Willebrand's factor, and collagen type I expression in MCG-treated ischemic wounds. At 21 days post wounding, MCG-treated ischemic wounds displayed higher abundance of proliferating endothelial cells that formed mature vascular structures and increased blood flow to the wound. Fibroblast count was markedly higher in MCG-treated ischemic wound-edge tissue. In addition, MCG-treated wound-edge tissues displayed higher abundance of mature collagen with increased collagen type I : III deposition. Taken together, MCG helped mount a more robust inflammatory response that resolved in a timely manner, followed by an enhanced proliferative phase, angiogenic outcome, and postwound tissue remodeling. Findings of the current study warrant clinical testing of MCG in a setting of ischemic chronic wounds.

  15. Progression of Pro23His Retinopathy in a Miniature Swine Model of Retinitis Pigmentosa

    PubMed Central

    Scott, Patrick A.; de Castro, Juan P. Fernandez; DeMarco, Paul J.; Ross, Jason W.; Njoka, Josephat; Walters, Eric; Prather, Randall S.; McCall, Maureen A.; Kaplan, Henry J.

    2017-01-01

    Purpose We characterize the progression of retinopathy in Filial 1 (F1) progeny of a transgenic (Tg) founder miniswine exhibiting severe Pro23His (P23H) retinopathy. Methods The F1 TgP23H miniswine progeny were created by crossing TgP23H founder miniswine 53-1 with wild type (WT) inbred miniature swine. Scotopic (rod-driven) and photopic (cone-driven) retinal functions were evaluated in F1 TgP23H and WT littermates using full field electroretinograms (ffERGs) at 1, 2, 3, 6, 9, 12, and 18 months of age, as well as the Tg founder miniswine at 6 years of age. Miniswine were euthanized and their retinas processed for morphologic evaluation at the light and electron microscopic level. Retinal morphology of a 36-month-old Tg miniswine also was examined. Results Wild type littermates reached mature scotopic and photopic retinal function by 3 months, while TgP23H miniswine showed abnormal scotopic ffERGs at the earliest time point, 1 month, and depressed photopic ffERGs after 2 months. Rod and cone photoreceptors (PR) exhibited morphologic abnormalities and dropout from the outer nuclear layer at 1 month, with only a monolayer of cone PR somata remaining after 2 months. The retinas showed progressive neural remodeling of the outer retina that included dendritic retraction of rod bipolar cells and glial seal formation by Müller cells. The TgP23H founder miniswine showed cone PR with relatively intact morphology exclusive to the area centralis. Conclusions The F1 Tg miniswine and the TgP23H founder miniswine exhibit similar retinopathy. Translational Relevance TgP23H miniswine are a useful large-eye model to study pathogenesis and preservation cone PRs in humans with retinitis pigmentosa. PMID:28316877

  16. Efficacy and safety of a new single-port model for appendectomy: Experimental study on swine

    PubMed Central

    Olijnyk, José Gustavo; Ferreira, Paulo Walter; Nácul, Miguel Prestes; Cavazzola, Leandro Totti

    2016-01-01

    CONTEXT: With the cooperation of surgeons and the engineering division of the company Bhio supply© (Esteio-RS, Brazil), a permanent single port was developed. AIMS: An experimental study assessed the safety and efficacy of the device using a swine laparoscopic appendectomy model (right salpingo-oophorectomy). SETTINGS AND DESIGN: Experimental randomised study. MATERIALS AND METHODS: A total of 20 pigs were randomised for the conventional laparoscopic (CL) three-trocar technique or the single Centry port (CPort) with two working channels, aided by a transparietal thread. Operative times, surgical complications, CO2 use, and pneumoperitoneal pressure were checked. Pressure and chromopertubation tests assessed the ligatures. STATISTICAL ANALYSIS USED: For quantitative outcomes, the Fisher's exact test analysed the samples to compare the surgeons in each group, the ANOVA test for parametric data (volume and pressure) and the Student's t-test for analysis of the fascial incision length. The binaries and isolated occurrence events were described in percentages. RESULTS: For all cases, pneumoperitoneum was maintained. The CPort group, however, resulted in higher CO2 use (26.18 l; standard deviation [SD] ± 11.09) than CL group (5.69 l; SD ± 2.44) (P < 0.01). The mean pressure in CPort group (6.604 mmHg, SD ± 1.793) was comparatively lower than in CL group (7.382 mmHg, SD ± 1.833) (P = 0.363). There was no statistical difference between operative times, ligature safety or adverse surgical events between the different groups and surgeons. CONCLUSION: The surgical technique used with the single port showed no differences in safety and efficacy. Though it does require more CO2 use, its working dynamics did not lead to increased operative times. The results were similar between the two surgeons in the study, suggesting that they can be reproduced. PMID:27073304

  17. Mechanical dissociation of swine liver to produce organoid units for tissue engineering and in vitro disease modeling.

    PubMed

    Irani, Katayun; Pomerantseva, Irina; Hart, Alison R; Sundback, Cathryn A; Neville, Craig M; Vacanti, Joseph P

    2010-01-01

    The complex intricate architecture of the liver is crucial to hepatic function. Standard protocols used for enzymatic digestion to isolate hepatocytes destroy tissue structure and result in significant loss of synthetic, metabolic, and detoxification processes. We describe a process using mechanical dissociation to generate hepatic organoids with preserved intrinsic tissue architecture from swine liver. Oxygen-supplemented perfusion culture better preserved organoid viability, morphology, serum protein synthesis, and urea production, compared with standard and oxygen-supplemented static culture. Hepatic organoids offer an alternative source for hepatic assist devices, engineered liver, disease modeling, and xenobiotic testing.

  18. Swine in biomedical research. V. 1

    SciTech Connect

    Tumbleson, M.E.

    1986-01-01

    This volume presents information on the following topics: the history of pigs; conceptual and operational history of the development of miniature swine; breeding program and population standards of the Gottingen miniature swine; moral, social and scientific aspects of the use of swine in research; fertility in gilts inseminated with frozen boar semen stored at -196 C for eight years; ultrastructure of piglet liver; porcine models in surgical research; anesthesia in swine; pulse monitoring, intravascular and instramuscular injection sites in pigs; collagen biosynthesis and collagen content as a measure of dermal healing in experimental wounds in domestic swine; methods for hair removal; swine as a cardiac surgical model; bone marrow transplantation in miniature swine; technical aspects of small intestinal transplantation in young pigs; models; the pig in studies of diarrhea pathophysiology; use of swine to validate airflow perturbation device for airways resistance measurements in humans; swine as a model for human diabetes; and the weanling Yorkshire pig as an animal model for measuring percutaneous penetration.

  19. Modeling Common Cause Failures of Thrusters on ISS Visiting Vehicles

    NASA Technical Reports Server (NTRS)

    Haught, Megan

    2014-01-01

    This paper discusses the methodology used to model common cause failures of thrusters on the International Space Station (ISS) Visiting Vehicles. The ISS Visiting Vehicles each have as many as 32 thrusters, whose redundancy makes them susceptible to common cause failures. The Global Alpha Model (as described in NUREG/CR-5485) can be used to represent the system common cause contribution, but NUREG/CR-5496 supplies global alpha parameters for groups only up to size six. Because of the large number of redundant thrusters on each vehicle, regression is used to determine parameter values for groups of size larger than six. An additional challenge is that Visiting Vehicle thruster failures must occur in specific combinations in order to fail the propulsion system; not all failure groups of a certain size are critical.

  20. Modeling Common Cause Failures of Thrusters on ISS Visiting Vehicles

    NASA Technical Reports Server (NTRS)

    Haught, Megan; Duncan, Gary

    2014-01-01

    This paper discusses the methodology used to model common cause failures of thrusters on the International Space Station (ISS) Visiting Vehicles. The ISS Visiting Vehicles each have as many as 32 thrusters, whose redundancy and similar design make them susceptible to common cause failures. The Global Alpha Model (as described in NUREG/CR-5485) can be used to represent the system common cause contribution, but NUREG/CR-5496 supplies global alpha parameters for groups only up to size six. Because of the large number of redundant thrusters on each vehicle, regression is used to determine parameter values for groups of size larger than six. An additional challenge is that Visiting Vehicle thruster failures must occur in specific combinations in order to fail the propulsion system; not all failure groups of a certain size are critical.

  1. Resuscitation with lactated ringer's does not increase inflammatory response in a Swine model of uncontrolled hemorrhagic shock.

    PubMed

    Watters, Jennifer M; Brundage, Susan I; Todd, S Rob; Zautke, Nathan A; Stefater, J A; Lam, J C; Muller, Patrick J; Malinoski, Darren; Schreiber, Martin A

    2004-09-01

    Lactated Ringer's (LR) and normal saline (NS) are widely and interchangeably used for resuscitation of trauma victims. Studies show LR to be superior to NS in the physiologic response to resuscitation. Recent in vitro studies demonstrate equivalent effects of LR and NS on leukocytes. We aimed to determine whether LR resuscitation would produce an equivalent inflammatory response compared with normal saline (NS) resuscitation in a clinically relevant swine model of uncontrolled hemorrhagic shock. Thirty-two swine were randomized. Control animals (n = 6) were sacrificed following induction of anesthesia for baseline data. Sham animals (n = 6) underwent laparotomy and 2 h of anesthesia. Uncontrolled hemorrhagic shock animals (n = 10/group) underwent laparotomy, grade V liver injury, and blinded resuscitation with LR or NS to maintain baseline blood pressure for 1.5 h before sacrifice. Lung was harvested, and tissue mRNA levels of interleukin-6 (IL-6), granulocyte colony-stimulating factor (G-CSF), and tumor necrosis factor-alpha (TNF-alpha) were determined using quantitative reverse transcriptase polymerase chain reaction (Q-RT-PCR). Sections of lung were processed and examined for neutrophils sequestered within the alveolar walls. Cytokine analysis showed no difference in IL-6 gene transcription in any group (P = 0.99). Resuscitated swine had elevated G-CSF and TNF-alpha gene transcription, but LR and NS groups were not different from each other (P= 0.96 and 0.10, respectively). Both resuscitation groups had significantly more alveolar neutrophils present than controls (P < 0.01) and shams (P < 0.05) but were not different from one another (P= 0.83). LR and NS resuscitation have equivalent effects on indices of inflammation in the lungs in our model of uncontrolled hemorrhagic shock.

  2. Instrumented failure of hillslope models with soil-pipes

    NASA Astrophysics Data System (ADS)

    Sharma, Raj H.; Konietzky, Heinz

    2011-07-01

    Soil-pipes (porous pipes inside a hillslope) are often detected in collapsed slopes indicating their influence on slope failure processes. Only limited studies can be found regarding the impacts of soil-pipes on landslide mechanisms. Hillslope models prepared in a flume are experimented with different soil-pipe configurations: a) no pipe, b) closed pipe and c) open pipe. Pore-water pressures were measured at six different locations along a slope. Discharges at the outlet of soil-pipe and groundwater seepage were also recorded. For the above mentioned pipe configurations two types of experiments were conducted: a) rainfall-induced failure and b) seepage-induced failure. Experimental results show that a closed pipe accumulates water around its lower end and continuously increases pore-water pressure till a failure. An open pipe works as a means of hillslope drainage and reduces the pore-water pressure of an entire slope. However, if open pipe is blocked, pore-water pressure close to its lower end rises rapidly, leading to immediate soil mass movement. For both seepage and rainfall-induced failure experiments, the maximum pressure before the failure was larger at a slope with an open pipe (once it is closed) than a slope with a pipe closed from the beginning or that without a soil-pipe. This indicates that the blockage of soil-pipes makes a slope more susceptible to failure. Displacement vectors show that soil movement velocity close to the surface was highest at slopes with open pipes after closure and lowest at slopes without pipes because of a higher degree of saturation and pore-water pressure at the time of failure of the former. Before a large failure, small fluctuations in pore-water pressure were also observed which can be an indicator of impending failure.

  3. Product component genealogy modeling and field-failure prediction

    SciTech Connect

    King, Caleb; Hong, Yili; Meeker, William Q.

    2016-04-13

    Many industrial products consist of multiple components that are necessary for system operation. There is an abundance of literature on modeling the lifetime of such components through competing risks models. During the life-cycle of a product, it is common for there to be incremental design changes to improve reliability, to reduce costs, or due to changes in availability of certain part numbers. These changes can affect product reliability but are often ignored in system lifetime modeling. By incorporating this information about changes in part numbers over time (information that is readily available in most production databases), better accuracy can be achieved in predicting time to failure, thus yielding more accurate field-failure predictions. This paper presents methods for estimating parameters and predictions for this generational model and a comparison with existing methods through the use of simulation. Our results indicate that the generational model has important practical advantages and outperforms the existing methods in predicting field failures.

  4. Miniature Swine for Preclinical Modeling of Complexities of Human Disease for Translational Scientific Discovery and Accelerated Development of Therapies and Medical Devices.

    PubMed

    Schomberg, Dominic T; Tellez, Armando; Meudt, Jennifer J; Brady, Dane A; Dillon, Krista N; Arowolo, Folagbayi K; Wicks, Joan; Rousselle, Serge D; Shanmuganayagam, Dhanansayan

    2016-04-01

    Noncommunicable diseases, including cardiovascular disease, diabetes, chronic respiratory disease, and cancer, are the leading cause of death in the world. The cost, both monetary and time, of developing therapies to prevent, treat, or manage these diseases has become unsustainable. A contributing factor is inefficient and ineffective preclinical research, in which the animal models utilized do not replicate the complex physiology that influences disease. An ideal preclinical animal model is one that responds similarly to intrinsic and extrinsic influences, providing high translatability and concordance of preclinical findings to humans. The overwhelming genetic, anatomical, physiological, and pathophysiological similarities to humans make miniature swine an ideal model for preclinical studies of human disease. Additionally, recent development of precision gene-editing tools for creation of novel genetic swine models allows the modeling of highly complex pathophysiology and comorbidities. As such, the utilization of swine models in early research allows for the evaluation of novel drug and technology efficacy while encouraging redesign and refinement before committing to clinical testing. This review highlights the appropriateness of the miniature swine for modeling complex physiologic systems, presenting it as a highly translational preclinical platform to validate efficacy and safety of therapies and devices.

  5. Prediction failure of a wolf landscape model

    USGS Publications Warehouse

    Mech, L.D.

    2006-01-01

    I compared 101 wolf (Canis lupus) pack territories formed in Wisconsin during 1993-2004 to the logistic regression predictive model of Mladenoff et al. (1995, 1997, 1999). Of these, 60% were located in putative habitat suitabilities 50% remained unoccupied by known packs after 24 years of recolonization. This model was a poor predictor of wolf re-colonizing locations in Wisconsin, apparently because it failed to consider the adaptability of wolves. Such models should be used cautiously in wolf-management or restoration plans.

  6. Development and Resuscitation of a Sedated, Mature Male Miniature Swine Severe Hemorrhage Model

    DTIC Science & Technology

    2011-07-01

    human and laboratory activity and trained to lie quietly in a sling with feet on the floor . The swine was hemorrhaged 60% of estimated blood volume (EBV...stopcocks were placed in all of the catheters, and the sling was lowered until the animal’s feet were on the floor . Midazolam infusion was started at 1.25...Hager P, Schmid ER. Monitoring level of sedation with bispectral EEG analysis: comparison between hypothermic and normo- thermic cardiopulmonary bypass

  7. In Vitro Continuous Fermentation Model (PolyFermS) of the Swine Proximal Colon for Simultaneous Testing on the Same Gut Microbiota

    PubMed Central

    Tanner, Sabine A.; Zihler Berner, Annina; Rigozzi, Eugenia; Grattepanche, Franck; Chassard, Christophe; Lacroix, Christophe

    2014-01-01

    In vitro gut modeling provides a useful platform for a fast and reproducible assessment of treatment-related changes. Currently, pig intestinal fermentation models are mainly batch models with important inherent limitations. In this study we developed a novel in vitro continuous fermentation model, mimicking the porcine proximal colon, which we validated during 54 days of fermentation. This model, based on our recent PolyFermS design, allows comparing different treatment effects on the same microbiota. It is composed of a first-stage inoculum reactor seeded with immobilized fecal swine microbiota and used to constantly inoculate (10% v/v) five second-stage reactors, with all reactors fed with fresh nutritive chyme medium and set to mimic the swine proximal colon. Reactor effluents were analyzed for metabolite concentrations and bacterial composition by HPLC and quantitative PCR, and microbial diversity was assessed by 454 pyrosequencing. The novel PolyFermS featured stable microbial composition, diversity and metabolite production, consistent with bacterial activity reported for swine proximal colon in vivo. The constant inoculation provided by the inoculum reactor generated reproducible microbial ecosystems in all second-stage reactors, allowing the simultaneous investigation and direct comparison of different treatments on the same porcine gut microbiota. Our data demonstrate the unique features of this novel PolyFermS design for the swine proximal colon. The model provides a tool for efficient, reproducible and cost-effective screening of environmental factors, such as dietary additives, on pig colonic fermentation. PMID:24709947

  8. Intravenous Cobinamide, a Novel Cyanide Antidote, versus Hydroxocobalamin in the Treatment of Acute Cyanide Toxicity and Apnea in a Swine (Sus scrofa) Model

    DTIC Science & Technology

    2013-02-12

    cobinamide, a novel cyanide antidote , versus hydroxocobalamin in the treatment of acute cyanide toxicity and apnea in a swine (Sus Scrofa) model...60min. Results:Weight, time to apnea, & CN dose similar (p>0.10). At treatment, blood CN, lactate levels, & decrease in MAP similar (p>0.10). 2/11 swine...in NS group survived(pɘ.001), compared to 10/11 in HOC & 10/11 in COB group. Time to breaths post treatment similar(HOC 1:48min, COB 1:49min). Blood

  9. Computational modeling for hexcan failure under core distruptive accidental conditions

    SciTech Connect

    Sawada, T.; Ninokata, H.; Shimizu, A.

    1995-09-01

    This paper describes the development of computational modeling for hexcan wall failures under core disruptive accident conditions of fast breeder reactors. A series of out-of-pile experiments named SIMBATH has been analyzed by using the SIMMER-II code. The SIMBATH experiments were performed at KfK in Germany. The experiments used a thermite mixture to simulate fuel. The test geometry of SIMBATH ranged from single pin to 37-pin bundles. In this study, phenomena of hexcan wall failure found in a SIMBATH test were analyzed by SIMMER-II. Although the original model of SIMMER-II did not calculate any hexcan failure, several simple modifications made it possible to reproduce the hexcan wall melt-through observed in the experiment. In this paper the modifications and their significance are discussed for further modeling improvements.

  10. Micromechanical Failure Analyses for Finite Element Polymer Modeling

    SciTech Connect

    CHAMBERS,ROBERT S.; REEDY JR.,EARL DAVID; LO,CHI S.; ADOLF,DOUGLAS B.; GUESS,TOMMY R.

    2000-11-01

    Polymer stresses around sharp corners and in constrained geometries of encapsulated components can generate cracks leading to system failures. Often, analysts use maximum stresses as a qualitative indicator for evaluating the strength of encapsulated component designs. Although this approach has been useful for making relative comparisons screening prospective design changes, it has not been tied quantitatively to failure. Accurate failure models are needed for analyses to predict whether encapsulated components meet life cycle requirements. With Sandia's recently developed nonlinear viscoelastic polymer models, it has been possible to examine more accurately the local stress-strain distributions in zones of likely failure initiation looking for physically based failure mechanisms and continuum metrics that correlate with the cohesive failure event. This study has identified significant differences between rubbery and glassy failure mechanisms that suggest reasonable alternatives for cohesive failure criteria and metrics. Rubbery failure seems best characterized by the mechanisms of finite extensibility and appears to correlate with maximum strain predictions. Glassy failure, however, seems driven by cavitation and correlates with the maximum hydrostatic tension. Using these metrics, two three-point bending geometries were tested and analyzed under variable loading rates, different temperatures and comparable mesh resolution (i.e., accuracy) to make quantitative failure predictions. The resulting predictions and observations agreed well suggesting the need for additional research. In a separate, additional study, the asymptotically singular stress state found at the tip of a rigid, square inclusion embedded within a thin, linear elastic disk was determined for uniform cooling. The singular stress field is characterized by a single stress intensity factor K{sub a} and the applicable K{sub a} calibration relationship has been determined for both fully bonded and

  11. Semi-parametric estimation in failure time mixture models.

    PubMed

    Taylor, J M

    1995-09-01

    A mixture model is an attractive approach for analyzing failure time data in which there are thought to be two groups of subjects, those who could eventually develop the endpoint and those who could not develop the endpoint. The proposed model is a semi-parametric generalization of the mixture model of Farewell (1982). A logistic regression model is proposed for the incidence part of the model, and a Kaplan-Meier type approach is used to estimate the latency part of the model. The estimator arises naturally out of the EM algorithm approach for fitting failure time mixture models as described by Larson and Dinse (1985). The procedure is applied to some experimental data from radiation biology and is evaluated in a Monte Carlo simulation study. The simulation study suggests the semi-parametric procedure is almost as efficient as the correct fully parametric procedure for estimating the regression coefficient in the incidence, but less efficient for estimating the latency distribution.

  12. Spatio-temporal modeling of the African swine fever epidemic in the Russian Federation, 2007-2012.

    PubMed

    Korennoy, F I; Gulenkin, V M; Malone, J B; Mores, C N; Dudnikov, S A; Stevenson, M A

    2014-10-01

    In 2007 African swine fever (ASF) entered Georgia and in the same year the disease entered the Russian Federation. From 2007 to 2012 ASF spread throughout the southern region of the Russian Federation. At the same time several cases of ASF were detected in the central and northern regions of the Russian Federation, forming a northern cluster of outbreaks in 2011. This northern cluster is of concern because of its proximity to mainland Europe. The aim of this study was to use details of recorded ASF outbreaks and human and swine population details to estimate the spatial distribution of ASF risk in the southern region of the European part of the Russian Federation. Our model of ASF risk was comprised of two components. The first was an estimate of ASF suitability scores calculated using maximum entropy methods. The second was an estimate of ASF risk as a function of Euclidean distance from index cases. An exponential distribution fitted to a frequency histogram of the Euclidean distance between consecutive ASF cases had a mean value of 156 km, a distance greater than the surveillance zone radius of 100-150 km stated in the ASF control regulations for the Russian Federation. We show that the spatial and temporal risk of ASF expansion is related to the suitability of the area of potential expansion, which is in turn a function of socio-economic and geographic variables. We propose that the methodology presented in this paper provides a useful tool to optimize surveillance for ASF in affected areas.

  13. Non-local models for ductile failure

    NASA Astrophysics Data System (ADS)

    César de Sá, José; Azinpour, Erfan; Santos, Abel

    2016-08-01

    Ductile damage can be dealt with continuous descriptions of material, resorting, for example, to continuous damage mechanic descriptions or micromechanical constitutive models. When it comes to describe material behaviour near and beyond fracture these approaches are no longer sufficient or valid and continuous/discontinuous approaches can be adopted to track fracture initiation and propagation. Apart from more pragmatic solutions like element erosion or remeshing techniques more advanced approaches based on the X-FEM concept, in particular associated with non-local formulations, may be adopted to numerically model these problems. Nevertheless, very often, for practical reasons, some important aspects are somewhat left behind, specially energetic requirements to promote the necessary transition of energy release associated with material damage and fracture energy associated to a crack creation and evolution. Phase-field methods may combine advantages of regularised continuous models by providing a similar description to non-local thermodynamical continuous damage mechanics, as well as, a "continuous" approach to numerically follow crack evolution and branching

  14. Modeling Failure Propagation in Large-Scale Engineering Networks

    NASA Astrophysics Data System (ADS)

    Schläpfer, Markus; Shapiro, Jonathan L.

    The simultaneous unavailability of several technical components within large-scale engineering systems can lead to high stress, rendering them prone to cascading events. In order to gain qualitative insights into the failure propagation mechanisms resulting from independent outages, we adopt a minimalistic model representing the components and their interdependencies by an undirected, unweighted network. The failure dynamics are modeled by an anticipated accelerated “wearout” process being dependent on the initial degree of a node and on the number of failed nearest neighbors. The results of the stochastic simulations imply that the influence of the network topology on the speed of the cascade highly depends on how the number of failed nearest neighbors shortens the life expectancy of a node. As a formal description of the decaying networks we propose a continuous-time mean field approximation, estimating the average failure rate of the nearest neighbors of a node based on the degree-degree distribution.

  15. Fuzzy modeling of analytical redundancy for sensor failure detection

    SciTech Connect

    Tsai, T.M.; Chou, H.P. )

    1991-01-01

    Failure detection and isolation (FDI) in dynamic systems may be accomplished by testing the consistency of the system via analytically redundant relations. The redundant relation is basically a mathematical model relating system inputs and dissimilar sensor outputs from which information is extracted and subsequently examined for the presence of failure signatures. Performance of the approach is often jeopardized by inherent modeling error and noise interference. To mitigate such effects, techniques such as Kalman filtering, auto-regression-moving-average (ARMA) modeling in conjunction with probability tests are often employed. These conventional techniques treat the stochastic nature of uncertainties in a deterministic manner to generate best-estimated model and sensor outputs by minimizing uncertainties. In this paper, the authors present a different approach by treating the effect of uncertainties with fuzzy numbers. Coefficients in redundant relations derived from first-principle physical models are considered as fuzzy parameters and on-line updated according to system behaviors. Failure detection is accomplished by examining the possibility that a sensor signal occurred in an estimated fuzzy domain. To facilitate failure isolation, individual FDI monitors are designed for each interested sensor.

  16. Preventing Phrenic Nerve Stimulation by a Patch Insulation in an Intact Swine Heart Model

    PubMed Central

    Hung, Yi-Wen; Hsieh, Yu-Cheng; Cheng, Chien-Ming; Wang, Kuo-Yang

    2014-01-01

    Introduction Phrenic nerve stimulation (PNS) could be prevented by a silastic patch over the epicardial lead. We studied the effects in preventing PNS by placing a silastic patch directly over an epicardial lead or placing a graft around the phrenic nerve (PN). Methods and Results Fourteen Lanyu swine were enrolled. A bipolar lead was placed epicardially on the left ventricle (LV) inferior to the PN. An implantable cardioverter-defibrillator (ICD) lead was placed into the right ventricle (RV). The maximal influential distance (MID) was measured under 3 pacing configurations to express the influential electrical field on the PN. The threshold of the LV and PN were evaluated epicardially. Then, PTFE patches of different sizes (10×10 mm, 20×20 mm and 30×30 mm) were placed between the LV lead and PN to study the rise in PN threshold in 7 swine. On the other hand, the PN were surrounded by a PTFE graft of different lengths (10 mm, 20 mm, and 30 mm) in the remaining 7 swine. LV-bipolar pacing showed the shortest MID when compared to the other 2 unipolar pacing configurations at pacing voltage of 10 V. The patch was most effective in preventing PNS during LV-bipolar pacing. PNS was prevented under all circumstances with a larger PTFE patch (30×30 mm) or long graft (30 mm). Conclusions PNS was avoided by placing a PTFE patch over the LV lead or a graft around the PN despite pacing configurations. Hence if PNS persisted during CRT implantation, a PTFE patch on the LV lead or a graft around the PN could be considered. PMID:25033271

  17. Diet-Induced Swine Model with Obesity/Leptin Resistance for the Study of Metabolic Syndrome and Type 2 Diabetes

    PubMed Central

    Torres-Rovira, L.; Astiz, S.; Caro, A.; Lopez-Bote, C.; Ovilo, C.; Pallares, P.; Perez-Solana, M. L.; Sanchez-Sanchez, R.; Gonzalez-Bulnes, A.

    2012-01-01

    The objective of the present study was to determine the suitability of a swine breed with leptin resistance and predisposition to obesity (the Iberian pig) as model for studies on metabolic syndrome and type 2 diabetes. Thus, six Iberian sows had ad libitum access to food enriched with saturated fat (SFAD group; food consumption was estimated to be 4.5 kg/animal/day) whilst four females acted as controls and were fed with 2 kg/animal/day of a commercial maintenance diet. After three months of differential feeding, SFAD animals developed central obesity, dyslipidemia, insulin resistance and impaired glucose tolerance, and elevated blood pressure; the five parameters associated with the metabolic syndrome. Thus, the current study characterizes the Iberian pig as a robust, amenable, and reliable translational model for studies on nutrition-associated diseases. PMID:22629144

  18. Swine production.

    PubMed

    Plain, Ronald L; Lawrence, John D

    2003-07-01

    The US swine industry is large and growing. The quantity of pork desired by consumers of US pork is growing at the rate of 1.5%/y. New production systems and new technology have enabled production per sow to grow at a rate of 4% annually in recent years. Consequently, the number of sows in the United States is declining. Because productivity growth is outpacing demand growth, the deflated price of hogs and pork is declining. Hog production and prices continue to exhibit strong seasonal and cyclic patterns. Pork production is usually lowest in the summer and highest in the fall. Production and prices tend to follow 4-year patterns. The US swine industry continues to evolve toward fewer and larger producers who rely on contracts for both hog production and marketing. In 2000, over half of the hogs marketed were from approximately 156 firms marketing more than 50,000 head annually. These producers finished 60% of their production in contract facilities. Over 90% of their marketings were under contract or were owned by a packer. These producers expressed a high level of satisfaction with hog production. Both they and their contract growers were satisfied with production contracts. These large producers were satisfied with their marketing contracts and planned to continue them in the future. The hog industry has changed a great deal in the last decade. There is little reason to believe this rapid rate of change will not continue. This swine industry is highly competitive and profit driven. Profit margins are too small to allow producers the luxury of ignoring new technology and innovative production systems. Consequently, hog production will continue its rapid evolution from traditional agriculture to typical industry.

  19. Bayesian failure probability model sensitivity study. Final report

    SciTech Connect

    Not Available

    1986-05-30

    The Office of the Manager, National Communications System (OMNCS) has developed a system-level approach for estimating the effects of High-Altitude Electromagnetic Pulse (HEMP) on the connectivity of telecommunications networks. This approach incorporates a Bayesian statistical model which estimates the HEMP-induced failure probabilities of telecommunications switches and transmission facilities. The purpose of this analysis is to address the sensitivity of the Bayesian model. This is done by systematically varying two model input parameters--the number of observations, and the equipment failure rates. Throughout the study, a non-informative prior distribution is used. The sensitivity of the Bayesian model to the noninformative prior distribution is investigated from a theoretical mathematical perspective.

  20. Controlling disease outbreaks in wildlife using limited culling: modelling classical swine fever incursions in wild pigs in Australia.

    PubMed

    Cowled, Brendan D; Garner, M Graeme; Negus, Katherine; Ward, Michael P

    2012-01-16

    Disease modelling is one approach for providing new insights into wildlife disease epidemiology. This paper describes a spatio-temporal, stochastic, susceptible- exposed-infected-recovered process model that simulates the potential spread of classical swine fever through a documented, large and free living wild pig population following a simulated incursion. The study area (300 000 km2) was in northern Australia. Published data on wild pig ecology from Australia, and international Classical Swine Fever data was used to parameterise the model. Sensitivity analyses revealed that herd density (best estimate 1-3 pigs km-2), daily herd movement distances (best estimate approximately 1 km), probability of infection transmission between herds (best estimate 0.75) and disease related herd mortality (best estimate 42%) were highly influential on epidemic size but that extraordinary movements of pigs and the yearly home range size of a pig herd were not. CSF generally established (98% of simulations) following a single point introduction. CSF spread at approximately 9 km2 per day with low incidence rates (< 2 herds per day) in an epidemic wave along contiguous habitat for several years, before dying out (when the epidemic arrived at the end of a contiguous sub-population or at a low density wild pig area). The low incidence rate indicates that surveillance for wildlife disease epidemics caused by short lived infections will be most efficient when surveillance is based on detection and investigation of clinical events, although this may not always be practical. Epidemics could be contained and eradicated with culling (aerial shooting) or vaccination when these were adequately implemented. It was apparent that the spatial structure, ecology and behaviour of wild populations must be accounted for during disease management in wildlife. An important finding was that it may only be necessary to cull or vaccinate relatively small proportions of a population to successfully contain

  1. Natural IgM Blockade Limits Infarct Expansion and Left Ventricular Dysfunction in a Swine Myocardial Infarct Model

    PubMed Central

    Sihag, Smita; Haas, Michael S.; Kim, Karen M.; Guerrero, J. Luis; Beaudoin, Jonathan; Alicot, Elisabeth M.; Schuerpf, Franziska; Gottschall, James D.; Puro, Robyn J.; Madsen, Joren C.; Sachs, David H.; Newman, Walter; Carroll, Michael C.; Allan, James S.

    2015-01-01

    Background Acute coronary syndrome is the leading cause of mortality worldwide. However, treatment of acute coronary occlusion inevitably results in ischemia-reperfusion (I/R) injury. Circulating natural IgM has been shown to play a significant role in mouse models of I/R injury. A highly conserved self-antigen, non-muscle myosin heavy chain II (NMHC-II), has been identified as a target of pathogenic IgM. We hypothesized that a monoclonal antibody (m21G6) directed against NMHC-II may inhibit IgM binding and reduce injury in a pre-clinical model of myocardial infarction (MI). Thus, our objective was to evaluate the efficacy of intravenous m21G6 treatment in limiting infarct expansion, troponin release, and left ventricular dysfunction in a swine MI model. Methods and Results MGH miniature swine underwent occlusion of the mid left anterior descending coronary artery for 60min, followed by 1h, 5d, or 21d reperfusion. Specificity and localization of m21G6 to injured myocardium were confirmed using fluorescently labeled m21G6. Treatment with m21G6 prior to reperfusion resulted in a 49% reduction in infarct size (p<0.005) and a 61% reduction in troponin-T levels (p<0.05) in comparison to saline controls at 5d reperfusion. Furthermore, m21G6 treated animals recovered 85.4% of their baseline left ventricular function as measured by two-dimensional transthoracic echocardiography (2D TTE) in contrast to 67.1% in controls at 21d reperfusion (p<0.05). Conclusions Treatment with m21G6 significantly reduced infarct size and troponin-T release, and led to marked preservation of cardiac function in our study. Overall, these findings suggest that pathogenic IgM blockade represents a valid therapeutic strategy in mitigating myocardial I/R injury. PMID:26671971

  2. Effect of Erythropoietin on Postresuscitation Renal Function in a Swine Model of Ventricular Fibrillation

    PubMed Central

    Kouskouni, Evangelia; Pliatsika, Paraskevi; Kaparos, Georgios; Barouxis, Dimitrios; Lelovas, Pavlos; Kotsilianou, Olympia; Pantazopoulos, Ioannis; Gkiokas, Georgios; Garosa, Clara

    2016-01-01

    Purpose. To investigate the effect of EPO administration on postresuscitation renal function. Methods. Twenty-four female Landrace/Large-White piglets aged 10–15 weeks with average weight of 19 ± 2 kg were randomly assigned to 2 different groups of 12 subjects each. After the end of an 8-minute ventricular fibrillation, the control group (Group C) received saline as placebo, whereas the EPO group (Group E) received EPO 5000 U/kg. The animals were resuscitated according to the 2010 European Resuscitation Council Guidelines for Resuscitation. Results. Five animals (41.67%) from Group C and 11 animals (91.67%) from Group E achieved ROSC (p = 0.027). Eight animals (66.67%, 5 surviving and 3 nonsurviving) from Group C suffered severe kidney damage or AKI compared to animals from Group E, in which none of the swine had evidence of severe kidney damage or AKI (p = 0.001). There was a statistically significant difference in all tested biochemical markers between the two groups, as well as a positive correlation of creatinine with NGAL, L-FABP, and IL-18 (summed mean values' p = 0.049, 0.01, and 0.004, resp.). Conclusions. Administration of EPO protected swine from postresuscitation acute kidney injury. PMID:27847811

  3. On rate-state and Coulomb failure models

    USGS Publications Warehouse

    Gomberg, J.; Beeler, N.; Blanpied, M.

    2000-01-01

    We examine the predictions of Coulomb failure stress and rate-state frictional models. We study the change in failure time (clock advance) Δt due to stress step perturbations (i.e., coseismic static stress increases) added to "background" stressing at a constant rate (i.e., tectonic loading) at time t0. The predictability of Δt implies a predictable change in seismicity rate r(t)/r0, testable using earthquake catalogs, where r0 is the constant rate resulting from tectonic stressing. Models of r(t)/r0, consistent with general properties of aftershock sequences, must predict an Omori law seismicity decay rate, a sequence duration that is less than a few percent of the mainshock cycle time and a return directly to the background rate. A Coulomb model requires that a fault remains locked during loading, that failure occur instantaneously, and that Δt is independent of t0. These characteristics imply an instantaneous infinite seismicity rate increase of zero duration. Numerical calculations of r(t)/r0 for different state evolution laws show that aftershocks occur on faults extremely close to failure at the mainshock origin time, that these faults must be "Coulomb-like," and that the slip evolution law can be precluded. Real aftershock population characteristics also may constrain rate-state constitutive parameters; a may be lower than laboratory values, the stiffness may be high, and/or normal stress may be lower than lithostatic. We also compare Coulomb and rate-state models theoretically. Rate-state model fault behavior becomes more Coulomb-like as constitutive parameter a decreases relative to parameter b. This is because the slip initially decelerates, representing an initial healing of fault contacts. The deceleration is more pronounced for smaller a, more closely simulating a locked fault. Even when the rate-state Δt has Coulomb characteristics, its magnitude may differ by some constant dependent on b. In this case, a rate-state model behaves like a modified

  4. Human recombinant relaxin reduces heart injury and improves ventricular performance in a swine model of acute myocardial infarction.

    PubMed

    Perna, Avio-Maria; Masini, Emanuela; Nistri, Silvia; Bani Sacchi, Tatiana; Bigazzi, Mario; Bani, Daniele

    2005-05-01

    This study shows that relaxin can be effective in the treatment of acute myocardial infarction. In a swine model of heart ischemia-reperfusion currently used to test cardiotropic drugs because of its similarities with human myocardial infarction, human recombinant relaxin (2.5 and 5 microg/kg body weight), given at reperfusion after a 30-min ischemia, markedly reduced the main serum markers of myocardial damage (myoglobin, CK-MB, and troponin T) and the metabolic and histopathologic parameters of myocardial inflammation and cardiomyocyte injury, resulting in overall improvement of ventricular performance (increased cardiac index) compared to the controls. These results provide a background for future clinical trials with human relaxin as adjunctive therapy to catheter-based coronary angioplasty in patients with acute myocardial infarction.

  5. Translational value of animal models of kidney failure.

    PubMed

    Ortiz, Alberto; Sanchez-Niño, Maria D; Izquierdo, Maria C; Martin-Cleary, Catalina; Garcia-Bermejo, Laura; Moreno, Juan A; Ruiz-Ortega, Marta; Draibe, Juliana; Cruzado, Josep M; Garcia-Gonzalez, Miguel A; Lopez-Novoa, Jose M; Soler, Maria J; Sanz, Ana B

    2015-07-15

    Acute kidney injury (AKI) and chronic kidney disease (CKD) are associated with decreased renal function and increased mortality risk, while the therapeutic armamentarium is unsatisfactory. The availability of adequate animal models may speed up the discovery of biomarkers for disease staging and therapy individualization as well as design and testing of novel therapeutic strategies. Some longstanding animal models have failed to result in therapeutic advances in the clinical setting, such as kidney ischemia-reperfusion injury and diabetic nephropathy models. In this regard, most models for diabetic nephropathy are unsatisfactory in that they do not evolve to renal failure. Satisfactory models for additional nephropathies are needed. These include anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, IgA nephropathy, anti-phospholipase-A2-receptor (PLA2R) membranous nephropathy and Fabry nephropathy. However, recent novel models hold promise for clinical translation. Thus, the AKI to CKD translation has been modeled, in some cases with toxins of interest for human CKD such as aristolochic acid. Genetically modified mice provide models for Alport syndrome evolving to renal failure that have resulted in clinical recommendations, polycystic kidney disease models that have provided clues for the development of tolvaptan, that was recently approved for the human disease in Japan; and animal models also contributed to target C5 with eculizumab in hemolytic uremic syndrome. Some ongoing trials explore novel concepts derived from models, such TWEAK targeting as tissue protection for lupus nephritis. We now review animal models reproducing diverse, genetic and acquired, causes of AKI and CKD evolving to kidney failure and discuss the contribution to clinical translation and prospects for the future.

  6. Product component genealogy modeling and field-failure prediction

    DOE PAGES

    King, Caleb; Hong, Yili; Meeker, William Q.

    2016-04-13

    Many industrial products consist of multiple components that are necessary for system operation. There is an abundance of literature on modeling the lifetime of such components through competing risks models. During the life-cycle of a product, it is common for there to be incremental design changes to improve reliability, to reduce costs, or due to changes in availability of certain part numbers. These changes can affect product reliability but are often ignored in system lifetime modeling. By incorporating this information about changes in part numbers over time (information that is readily available in most production databases), better accuracy can bemore » achieved in predicting time to failure, thus yielding more accurate field-failure predictions. This paper presents methods for estimating parameters and predictions for this generational model and a comparison with existing methods through the use of simulation. Our results indicate that the generational model has important practical advantages and outperforms the existing methods in predicting field failures.« less

  7. Effect of three different bariatric obesity surgery procedures on nutrient and energy digestibility using a swine experimental model

    PubMed Central

    Hodgkinson, Suzanne Marie; Riveros, José Luis; Bas, Fernando

    2015-01-01

    Morbid obesity is a worldwide health concern that compromises life quality and health status of obese human subjects. Bariatric surgery for treating morbid obesity remains as one of the best alternatives to promote excess weight loss and to reduce co-morbidities. We have not found studies reporting nutrients and energy balance considering digestibility trials in humans following surgery. The purpose of this study was to determine protein, lipid, fiber, energy, calcium, and phosphorous digestibility in a swine model that underwent ileal transposition (IT), sleeve gastrectomy with ileal transposition (SGIT), Roux-en-Y gastric bypass (RYGBP), and with sham operated animals (SHAM). Thirty-two pigs were randomly assigned to four laparoscopic procedures: IT (n = 8), RYGBP (n = 8), SGIT (n = 8), and Sham-operated pigs (n = 8). From day 0 postsurgery to 130, pigs were weighed monthly to determine live weight and weight gain was calculated for each month postsurgery until day 130. Food intake in a metabolic weight basis was calculated by measuring ad libitum food intake at day 130. Swine were fitted into metabolic crates to determine digestibility coefficients of dry matter, protein, fat, fiber, ash, energy, calcium, and phosphorous from day 130. A one-way ANOVA and Student–Newman–Keuls were used to detect differences in weight, food intake, and digestibility coefficients. Digestibility values for dry matter, fiber, phosphorus, and energy showed no differences among groups (P > 0.05). However, significant differences (P ≤ 0.05) were encountered among groups for fat, protein, ash, and calcium digestibilities. The RYGBP procedure, when applied to the pig model, significantly reduced calcium, fat, and ash digestibility, which did not occur with SGIT or IT procedure, when compared with Sham-operated animals. PMID:25711878

  8. Effect of three different bariatric obesity surgery procedures on nutrient and energy digestibility using a swine experimental model.

    PubMed

    Gandarillas, Mónica; Hodgkinson, Suzanne Marie; Riveros, José Luis; Bas, Fernando

    2015-09-01

    Morbid obesity is a worldwide health concern that compromises life quality and health status of obese human subjects. Bariatric surgery for treating morbid obesity remains as one of the best alternatives to promote excess weight loss and to reduce co-morbidities. We have not found studies reporting nutrients and energy balance considering digestibility trials in humans following surgery. The purpose of this study was to determine protein, lipid, fiber, energy, calcium, and phosphorous digestibility in a swine model that underwent ileal transposition (IT), sleeve gastrectomy with ileal transposition (SGIT), Roux-en-Y gastric bypass (RYGBP), and with sham operated animals (SHAM). Thirty-two pigs were randomly assigned to four laparoscopic procedures: IT (n = 8), RYGBP (n = 8), SGIT (n = 8), and Sham-operated pigs (n = 8). From day 0 postsurgery to 130, pigs were weighed monthly to determine live weight and weight gain was calculated for each month postsurgery until day 130. Food intake in a metabolic weight basis was calculated by measuring ad libitum food intake at day 130. Swine were fitted into metabolic crates to determine digestibility coefficients of dry matter, protein, fat, fiber, ash, energy, calcium, and phosphorous from day 130. A one-way ANOVA and Student-Newman-Keuls were used to detect differences in weight, food intake, and digestibility coefficients. Digestibility values for dry matter, fiber, phosphorus, and energy showed no differences among groups (P > 0.05). However, significant differences (P ≤ 0.05) were encountered among groups for fat, protein, ash, and calcium digestibilities. The RYGBP procedure, when applied to the pig model, significantly reduced calcium, fat, and ash digestibility, which did not occur with SGIT or IT procedure, when compared with Sham-operated animals.

  9. A statistical model of carbon/carbon composite failure

    NASA Technical Reports Server (NTRS)

    Slattery, Kerry T.

    1991-01-01

    A failure model which considers the stochastic nature of the damage accumulation process is essential to assess reliability and to accurately scale the results from standard test specimens to composite structures. A superior filamentary composite for high temperature applications is composed of carbon fibers in a carbon matrix. Carbon-carbon composites are the strongest known material at very high temperatures. Since there appears to be a significant randomness in C-C material strength which cannot be controlled or detected with current technology, a better model of the material failure based upon statistical principles should be used. Simple applications of the model based upon the limited data provide encouraging results that indicate that better design of test specimens would provide a substantially higher prediction for the design strength of C-C composites. An A-basis strength for the C-C tensile rings from a first stage D-5 billets was estimated. A statistical failure model was developed for these rings which indicates that this strength may be very conservative for larger C-C parts. The analysis may be improved by use of a heterogeneous/noncontinuum finite element approach on the minimechanical level.

  10. Evaluation of the Role of Cisplatin-conjugated-soluble Gelatin Sponge: Feasibility Study in a Swine Model

    SciTech Connect

    Ikoma, Akira; Kawai, Nobuyuki; Sato, Morio Minamiguchi, Hiroyuki; Nakata, Kouhei; Nakai, Motoki; Sanda, Hiroki; Sonomura, Tetsuo; Kanayama, Yoshitaka; Sakai, Yasuo

    2013-08-01

    PurposeTo evaluate the safety and the delivery function of cisplatin-conjugated-soluble gelatin sponge in a swine model.MethodsFifteen healthy young swine were assigned into three groups: transarterial cisplatin infusion group, transarterial chemoembolization (TACE) with cisplatin-conjugated 120-min soluble gelatin sponge (TACE-120) group, and TACE with cisplatin-conjugated 360-min soluble gelatin sponge (TACE-360) group. A total volume of 0.8 mL/kg cisplatin in each group and 8 mg/kg soluble gelatin sponge in TACE-120 and TACE-360 groups were injected from the left hepatic artery in small increments for 10 min. Common hepatic angiography and whole-blood sampling via the left hepatic vein were conducted to explore recanalization immediately after the procedure and again at 10, 30, 60, 90, 120, 180, 240, 300, 360, and 420 min later. The area under the plasma concentration curve (AUC) of non-protein-bound platinum was compared among the three groups. Each liver was removed and cut into 10-cm-thick sections for calculating liver-damaged volume ratio.ResultsSequential angiography depicted gradual recanalization of the occluded hepatic artery and total recanalization at 120 and 360 min after embolization in the TACE-120 and TACE-360 groups, respectively. Of the three groups, AUC{sub 0-30}, AUC{sub 30-120}, and AUC{sub 120-420} were significantly highest in the transarterial cisplatin infusion group (p < 0.001), the TACE-120 group (p < 0.001), and the TACE-360 group (p < 0.001), respectively. The liver-damaged volume ratio in the TACE-360 group was small (8.20 %) but significantly higher than that in the TACE-120 group (2.67 %, p = 0.014).ConclusionCisplatin-conjugated soluble gelatin sponge functions as a cisplatin carrier and is associated with tolerable liver damage.

  11. A Comparison of Proximal Tibia, Proximal Humerus and Distal Femur Infusion Rates of Blood Under High Pressure Using the EX IO Intraosseous Device in the Adult Swine (Sus scrofa) Hypovolemic Model

    DTIC Science & Technology

    2012-07-25

    of Blood Under High Pressure Using the EZ IO Intraosseous Device on the Adult Swine (Sus scrofa) hypovolemic Model.” 4. Principal Investigator... hypovolemic period and decreased after infusion of blood. In the femur arm the serum lactate increased until the experiment ended. Histopathologic...vascular resistance in our pilot, dose-finding hemorrhagic shock swine model. The blood pressure response paralleled increasing drug dose

  12. Reciprocating compressor valve failure -- Digital modelling and analysis

    SciTech Connect

    Motriuk, R.W.

    1996-12-31

    Many problems in reciprocating compressors are caused by valve failures. Usually, valve failures are diagnosed early, and the worn out parts are replaced. This requires, however, unscheduled compressor shutdowns which increase the cost of operation and possibly breach gas delivery contracts. Thus, it is essential to design valves adequate for the particular compressors and flow conditions. In this paper, it is determined that the cause of an unusually large number of valve failures at one of the NOVA Gas Transmission Limited (NGTL) compressor stations was an inadequate valve design. It is shown that the type of valve presently used is unacceptable and should be replaced. Due to economic restrictions, however, the existing valves are modified rather than replaced. The method used to re-design the compressor valves includes two steps: field measurements and computer digital modelling. The modelling incorporates: (1) acoustic simulation of the system, (2) compressor valve dynamic simulation, and (3) simultaneous simulation of fluid solid interactions between the compressor valves, compressor cylinders and pipework. The results obtained by using models of (2) and (3) are compared.

  13. A novel swine model of ricin-induced acute respiratory distress syndrome

    PubMed Central

    Katalan, Shahaf; Falach, Reut; Rosner, Amir; Goldvaser, Michael; Brosh-Nissimov, Tal; Dvir, Ayana; Mizrachi, Avi; Goren, Orr; Cohen, Barak; Gal, Yoav; Sapoznikov, Anita; Ehrlich, Sharon; Kronman, Chanoch

    2017-01-01

    ABSTRACT Pulmonary exposure to the plant toxin ricin leads to respiratory insufficiency and death. To date, in-depth study of acute respiratory distress syndrome (ARDS) following pulmonary exposure to toxins is hampered by the lack of an appropriate animal model. To this end, we established the pig as a large animal model for the comprehensive study of the multifarious clinical manifestations of pulmonary ricinosis. Here, we report for the first time, the monitoring of barometric whole body plethysmography for pulmonary function tests in non-anesthetized ricin-treated pigs. Up to 30 h post-exposure, as a result of progressing hypoxemia and to prevent carbon dioxide retention, animals exhibited a compensatory response of elevation in minute volume, attributed mainly to a large elevation in respiratory rate with minimal response in tidal volume. This response was followed by decompensation, manifested by a decrease in minute volume and severe hypoxemia, refractory to oxygen treatment. Radiological evaluation revealed evidence of early diffuse bilateral pulmonary infiltrates while hemodynamic parameters remained unchanged, excluding cardiac failure as an explanation for respiratory insufficiency. Ricin-intoxicated pigs suffered from increased lung permeability accompanied by cytokine storming. Histological studies revealed lung tissue insults that accumulated over time and led to diffuse alveolar damage. Charting the decline in PaO2/FiO2 ratio in a mechanically ventilated pig confirmed that ricin-induced respiratory damage complies with the accepted diagnostic criteria for ARDS. The establishment of this animal model of pulmonary ricinosis should help in the pursuit of efficient medical countermeasures specifically tailored to deal with the respiratory deficiencies stemming from ricin-induced ARDS. PMID:28067630

  14. Case–Cohort Analysis with Accelerated Failure Time Model

    PubMed Central

    Kong, Lan; Cai, Jianwen

    2010-01-01

    Summary In a case–cohort design, covariates are assembled only for a subcohort that is randomly selected from the entire cohort and any additional cases outside the subcohort. This design is appealing for large cohort studies of rare disease, especially when the exposures of interest are expensive to ascertain for all the subjects. We propose statistical methods for analyzing the case–cohort data with a semiparametric accelerated failure time model that interprets the covariates effects as to accelerate or decelerate the time to failure. Asymptotic properties of the proposed estimators are developed. The finite sample properties of case–cohort estimator and its relative efficiency to full cohort estimator are assessed via simulation studies. A real example from a study of cardiovascular disease is provided to illustrate the estimating procedure. PMID:18537948

  15. Swine: Selection and Evaluation.

    ERIC Educational Resources Information Center

    Clemson Univ., SC. Vocational Education Media Center.

    Designed for secondary vocational agriculture students, this text provides an overview of selecting and evaluating swine in Future Farmers of America livestock judging events. The first of four major sections addresses topics such as the main points in evaluating market hogs and breeding swine and provides an example class of swine. Section 2,…

  16. RECONFIGURING POWER SYSTEMS TO MINIMIZE CASCADING FAILURES: MODELS AND ALGORITHMS

    SciTech Connect

    Bienstock, Daniel

    2014-04-11

    the main goal of this project was to develop new scientific tools, based on optimization techniques, with the purpose of controlling and modeling cascading failures of electrical power transmission systems. We have developed a high-quality tool for simulating cascading failures. The problem of how to control a cascade was addressed, with the aim of stopping the cascade with a minimum of load lost. Yet another aspect of cascade is the investigation of which events would trigger a cascade, or more appropriately the computation of the most harmful initiating event given some constraint on the severity of the event. One common feature of the cascade models described (indeed, of several of the cascade models found in the literature) is that we study thermally-induced line tripping. We have produced a study that accounts for exogenous randomness (e.g. wind and ambient temperature) that could affect the thermal behavior of a line, with a focus on controlling the power flow of the line while maintaining safe probability of line overload. This was done by means of a rigorous analysis of a stochastic version of the heat equation. we incorporated a model of randomness in the behavior of wind power output; again modeling an OPF-like problem that uses chance-constraints to maintain low probability of line overloads; this work has been continued so as to account for generator dynamics as well.

  17. Measurement, analysis, and modeling of hydrogen sulfide emissions from a swine facility in North Carolina

    NASA Astrophysics Data System (ADS)

    Blunden, Jessica

    Annual global source contributions of sulfur compounds to the natural atmospheric environment are estimated to be 142 x 106 tons. Although not quantified, volatilization from animal wastes may be an important source of gaseous reduced sulfur compounds. Hydrogen sulfide (H2S) is a colorless gas emitted during decomposition of hog manure that produces an offensive "rotten egg" odor. Once released into the atmosphere, H 2S is oxidized and the eventual byproduct, sulfuric acid, may combine with other atmospheric constituents to form aerosol products such as ammonium bisulfate and ammonium sulfate. In recent years, confined animal feeding operations (CAFOs) have increased in size, resulting in more geographically concentrated areas of animals and, subsequently, animal waste. In North Carolina and across the southeastern United States anaerobic waste treatment lagoons are traditionally used to store and treat hog excreta at commercial hog farms. Currently, no state regulations exist for H2S gaseous emissions from animal production facilities in North Carolina and the amount of H2S being emitted into the atmosphere from these potential sources is widely unknown. In response to the need for data, this research initiative has been undertaken in an effort to quantify emissions of H2S from swine CAFOs. An experimental study was conducted at a commercial swine farm in eastern North Carolina to measure hydrogen sulfide emissions from a hog housing unit utilizing a mechanical fan ventilation system and from an on-site waste storage treatment lagoon. A dynamic flow-through chamber system was employed to make lagoon flux measurements. Semi-continuous measurements were made over a one-year period (2004-2005) for a few days during each of the four predominant seasons in order to assess diurnal and temporal variability in emissions. Fan rpm from the barn was continuously measured and flow rates were calculated in order to accurately assess gaseous emissions from the system

  18. The Effect of Hypotensive Resuscitation and Fluid Type on Mortality, Bleeding, Coagulation, & Dysfunctional Inflammation in a Swine Grade V Liver Injury Model

    DTIC Science & Technology

    2007-01-01

    defined by the American Association for the Surgery of Trauma Organ Injury Scaling System. This model has been described in several prior studies...fasted for 16 hours prior to surgery , except for water ad libitum. We pre-anesthatized the swine with an intramuscular injection of 8mg/kg Telazol...through measurement of jaw laxity, hemodynamic fluxuations, and response to painful stimuli at the nasal septum and forefoot . All efforts were made to

  19. A Prospective, Randomized Trial of Intravenous Hydroxocobalamin Versus Whole Blood Transfusion Compared to No Treatment for Class III Hemorrhagic Shock Resuscitation in a Prehospital Swine Model

    DTIC Science & Technology

    2015-03-01

    Drug Administration (FDA) for treat- ment of cyanide toxicity after efficacy was documented both in animal studies and in human case series in Europe...10 Hydroxocobalamin has been shown to effec- tively increase blood pressure in cyanide -induced car- diac arrest and endotoxin-induced hypotension.11–13...In previous studies examining the efficacy of hydroxoco- balamin to treat cyanide toxicity in a swine model of acute severe cyanide toxicity, it also

  20. Conceptual modeling of coincident failures in multiversion software

    NASA Technical Reports Server (NTRS)

    Littlewood, Bev; Miller, Douglas R.

    1989-01-01

    Recent work by Eckhardt and Lee (1985) shows that independently developed program versions fail dependently (specifically, simultaneous failure of several is greater than would be the case under true independence). The present authors show there is a precise duality between input choice and program choice in this model and consider a generalization in which different versions can be developed using diverse methodologies. The use of diverse methodologies is shown to decrease the probability of the simultaneous failure of several versions. Indeed, it is theoretically possible to obtain versions which exhibit better than independent failure behavior. The authors try to formalize the notion of methodological diversity by considering the sequence of decision outcomes that constitute a methodology. They show that diversity of decision implies likely diversity of behavior for the different verions developed under such forced diversity. For certain one-out-of-n systems the authors obtain an optimal method for allocating diversity between versions. For two-out-of-three systems there seem to be no simple optimality results which do not depend on constraints which cannot be verified in practice.

  1. ISSUES ASSOCIATED WITH PROBABILISTIC FAILURE MODELING OF DIGITAL SYSTEMS

    SciTech Connect

    CHU,T.L.; MARTINEZ-GURIDI,G.; LEHNER,J.; OVERLAND,D.

    2004-09-19

    The current U.S. Nuclear Regulatory Commission (NRC) licensing process of instrumentation and control (I&C) systems is based on deterministic requirements, e.g., single failure criteria, and defense in depth and diversity. Probabilistic considerations can be used as supplements to the deterministic process. The National Research Council has recommended development of methods for estimating failure probabilities of digital systems, including commercial off-the-shelf (COTS) equipment, for use in probabilistic risk assessment (PRA). NRC staff has developed informal qualitative and quantitative requirements for PRA modeling of digital systems. Brookhaven National Laboratory (BNL) has performed a review of the-state-of-the-art of the methods and tools that can potentially be used to model digital systems. The objectives of this paper are to summarize the review, discuss the issues associated with probabilistic modeling of digital systems, and identify potential areas of research that would enhance the state of the art toward a satisfactory modeling method that could be integrated with a typical probabilistic risk assessment.

  2. Using heterogeneity in the population structure of U.S. swine farms to compare transmission models for porcine epidemic diarrhoea.

    PubMed

    O'Dea, Eamon B; Snelson, Harry; Bansal, Shweta

    2016-03-07

    In 2013, U.S. swine producers were confronted with the disruptive emergence of porcine epidemic diarrhoea (PED). Movement of animals among farms is hypothesised to have played a role in the spread of PED among farms. Via this or other mechanisms, the rate of spread may also depend on the geographic density of farms and climate. To evaluate such effects on a large scale, we analyse state-level counts of outbreaks with variables describing the distribution of farm sizes and types, aggregate flows of animals among farms, and an index of climate. Our first main finding is that it is possible for a correlation analysis to be sensitive to transmission model parameters. This finding is based on a global sensitivity analysis of correlations on simulated data that included a biased and noisy observation model based on the available PED data. Our second main finding is that flows are significantly associated with the reports of PED outbreaks. This finding is based on correlations of pairwise relationships and regression modeling of total and weekly outbreak counts. These findings illustrate how variation in population structure may be employed along with observational data to improve understanding of disease spread.

  3. A mixture Weibull proportional hazard model for mechanical system failure prediction utilising lifetime and monitoring data

    NASA Astrophysics Data System (ADS)

    Zhang, Qing; Hua, Cheng; Xu, Guanghua

    2014-02-01

    As mechanical systems increase in complexity, it is becoming more and more common to observe multiple failure modes. The system failure can be regarded as the result of interaction and competition between different failure modes. It is therefore necessary to combine multiple failure modes when analysing the failure of an overall system. In this paper, a mixture Weibull proportional hazard model (MWPHM) is proposed to predict the failure of a mechanical system with multiple failure modes. The mixed model parameters are estimated by combining historical lifetime and monitoring data of all failure modes. In addition, the system failure probability density is obtained by proportionally mixing the failure probability density of multiple failure modes. Monitoring data are input into the MWPHM to estimate the system reliability and predict the system failure time. A simulated sample set is used to verify the ability of the MWPHM to model multiple failure modes. Finally, the MWPHM and the traditional Weibull proportional hazard model (WPHM) are applied to a high-pressure water descaling pump, which has two failure modes: sealing ring wear and thrust bearing damage. Results show that the MWPHM is greatly superior in system failure prediction to the WPHM.

  4. Peridynamic Modeling of Fracture and Failure of Materials

    DTIC Science & Technology

    2013-08-02

    failure loads approach the measured values. 4.3.2.1 Laminated plate with a center hole The quasi-isotropic AS4/3501-6 carbon/ epoxy composite ...both the failure progression and residual strength of monolithic and composite laminates. Predicting damage and residual strengths of composite ...demonstrated by predicting failure loads and final failure peridynamics, composites , progressive failure 42 Erdogan Madenci 52-250-1399

  5. Intracoronary artery transplantation of cardiomyoblast-like cells from human adipose tissue-derived multi-lineage progenitor cells improve left ventricular dysfunction and survival in a swine model of chronic myocardial infarction

    SciTech Connect

    Okura, Hanayuki; Saga, Ayami; Soeda, Mayumi; Miyagawa, Shigeru; Sawa, Yoshiki; Daimon, Takashi; Ichinose, Akihiro; Matsuyama, Akifumi

    2012-09-07

    Highlights: Black-Right-Pointing-Pointer We administered human CLCs in a swine model of MI via intracoronary artery. Black-Right-Pointing-Pointer Histological studies demonstrated engraftment of hCLCs into the scarred myocardium. Black-Right-Pointing-Pointer Echocardiography showed rescue of cardiac function in the hCLCs transplanted swine. Black-Right-Pointing-Pointer Transplantation of hCLCs is an effective therapeutics for cardiac regeneration. -- Abstract: Transplantation of human cardiomyoblast-like cells (hCLCs) from human adipose tissue-derived multi-lineage progenitor cells improved left ventricular function and survival of rats with myocardial infarction. Here we examined the effect of intracoronary artery transplantation of human CLCs in a swine model of chronic heart failure. Twenty-four pigs underwent balloon-occlusion of the first diagonal branch followed by reperfusion, with a second balloon-occlusion of the left ascending coronary artery 1 week later followed by reperfusion. Four weeks after the second occlusion/reperfusion, 17 of the 18 surviving animals with severe chronic MI (ejection fraction <35% by echocardiography) were immunosuppressed then randomly assigned to receive either intracoronary artery transplantation of hCLCs hADMPCs or placebo lactic Ringer's solution with heparin. Intracoronary artery transplantation was followed by the distribution of DiI-stained hCLCs into the scarred myocardial milieu. Echocardiography at post-transplant days 4 and 8 weeks showed rescue and maintenance of cardiac function in the hCLCs transplanted group, but not in the control animals, indicating myocardial functional recovery by hCLCs intracoronary transplantation. At 8 week post-transplantation, 7 of 8 hCLCs transplanted animals were still alive compared with only 1 of the 5 control (p = 0.0147). Histological studies at week 12 post-transplantation demonstrated engraftment of the pre DiI-stained hCLCs into the scarred myocardium and their expression of

  6. Utilization of laser Doppler flowmetry and tissue spectrophotometry for burn depth assessment using a miniature swine model.

    PubMed

    Lotter, Oliver; Held, Manuel; Schiefer, Jennifer; Werner, Ole; Medved, Fabian; Schaller, Hans-Eberhard; Rahmanian-Schwarz, Afshin; Jaminet, Patrick; Rothenberger, Jens

    2015-01-01

    Currently, the diagnosis of burn depth is primarily based on a visual assessment and can be dependent on the surgeons' experience. The goal of this study was to determine the ability of laser Doppler flowmeter combined with a tissue spectrophotometer to discriminate burn depth in a miniature swine burn model. Burn injuries of varying depth, including superficial-partial, deep-partial, and full thickness, were created in seven Göttingen minipigs using an aluminium bar (100 °C), which was applied to the abdominal skin for periods of 1, 3, 6, 12, 30, and 60 seconds with gravity alone. The depth of injury was evaluated histologically using hematoxylin and eosin staining. All burns were assessed 3 hours after injury using a device that combines a laser light and a white light to determine blood flow, hemoglobin oxygenation, and relative amount of hemoglobin. The blood flow (41 vs. 124 arbitrary units [AU]) and relative amount of hemoglobin (32 vs. 52 AU) were significantly lower in full thickness compared with superficial-partial thickness burns. However, no significant differences in hemoglobin oxygenation were observed between these depths of burns (61 vs. 60%). These results show the ability of laser Doppler flowmeter and tissue spectrophotometer in combination to discriminate between various depths of injury in the minipig model, suggesting that this device may offer a valuable tool for burn depth assessment influencing burn management.

  7. An evaluation of two conducted electrical weapons and two probe designs using a swine comparative cardiac safety model.

    PubMed

    Dawes, Donald Murray; Ho, Jeffrey D; Moore, Johanna C; Miner, James R

    2013-09-01

    Despite human laboratory and field studies that have demonstrated a reasonable safety profile for TASER brand conducted electrical weapons (CEW), the results of some swine studies and arrest related deaths temporal to the use of the CEWs continue to raise questions regarding cardiac safety. TASER International, Inc., has released a new CEW, the TASER X2, touted to have a better safety profile than its long-standing predecessor, the TASER X26. We have developed a model to assess the relative cardiac safety of CEWs and used it to compare the TASER X2 and the TASER X26. This safety model was also used to assess the relative safety of an experimental probe design as compared to the standard steel probe. Our results suggest that the TASER X2 has an improved safety margin over the TASER X26. The new probe design also has promise for enhanced cardiac safety, although may have some disadvantages when compared to the existing design which would make field use impractical.

  8. 9 CFR 94.14 - Swine from regions where swine vesicular disease exists; importations prohibited.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... PATHOGENIC AVIAN INFLUENZA, AFRICAN SWINE FEVER, CLASSICAL SWINE FEVER, SWINE VESICULAR DISEASE, AND BOVINE SPONGIFORM ENCEPHALOPATHY: PROHIBITED AND RESTRICTED IMPORTATIONS § 94.14 Swine from regions where...

  9. A Model for Assessment of Failure of LWR Fuel during an RIA

    SciTech Connect

    Liu, Wenfeng; Kazimi, Mujid S.

    2007-07-01

    This paper presents a model for Pellet-Cladding Mechanical Interaction (PCMI) failure of LWR fuel during an RIA. The model uses the J-integral as a driving parameter to characterize the failure potential during PCMI. The model is implemented in the FRAPTRAN code and is validated by CABRI and NSRR simulated RIA test data. Simulation of PWR and BWR conditions are conducted by FRAPTRAN to evaluate the fuel failure potential using this model. Model validation and simulation results are compared with the strain-based failure model of PNNL and the SED/CSED model of EPRI. Our fracture mechanics model has good capability to differentiate failure from non-failure cases. The results reveal significant effects of power pulse width: a wider pulse width generally increases the threshold for fuel failure. However, this effect is less obvious for highly corroded cladding. (authors)

  10. Modelling progressive autonomic failure in MSA: where are we now?

    PubMed

    Stemberger, Sylvia; Wenning, Gregor K

    2011-05-01

    Multiple system atrophy (MSA) is a fatal late-onset α-synucleinopathy that presents with features of ataxia, Parkinsonism, and pyramidal dysfunction in any combination. Over the last decade, efforts have been made to develop preclinical MSA testbeds for novel interventional strategies. The main focus has been on murine analogues of MSA-linked motor features and their underlying brainstem, cerebellar and basal ganglia pathology. Although progressive autonomic failure (AF) is a prominent clinical feature of patients with MSA, reflecting a disruption of both central and peripheral autonomic networks controlling cardiovascular, respiratory, urogenital, gastrointestinal and sudomotor functions, attempts of modelling this aspect of the human disease have been limited. However, emerging evidence suggests that AF-like features may occur in transgenic MSA models reflecting α-synucleinopathy lesions in distributed autonomic networks. Further research is needed to fully characterize both autonomic and motor features in optimized preclinical MSA models.

  11. Understanding African Swine Fever infection dynamics in Sardinia using a spatially explicit transmission model in domestic pig farms.

    PubMed

    Mur, L; Sánchez-Vizcaíno, J M; Fernández-Carrión, E; Jurado, C; Rolesu, S; Feliziani, F; Laddomada, A; Martínez-López, B

    2017-03-13

    African swine fever virus (ASFV) has been endemic in Sardinia since 1978, resulting in severe losses for local pig producers and creating important problems for the island's veterinary authorities. This study used a spatially explicit stochastic transmission model followed by two regression models to investigate the dynamics of ASFV spread amongst domestic pig farms, to identify geographic areas at highest risk and determine the role of different susceptible pig populations (registered domestic pigs, non-registered domestic pigs [brado] and wild boar) in ASF occurrence. We simulated transmission within and between farms using an adapted version of the previously described model known as Be-FAST. Results from the model revealed a generally low diffusion of ASF in Sardinia, with only 24% of the simulations resulting in disease spread, and for each simulated outbreak on average only four farms and 66 pigs were affected. Overall, local spread (indirect transmission between farms within a 2 km radius through fomites) was the most common route of transmission, being responsible for 98.6% of secondary cases. The risk of ASF occurrence for each domestic pig farm was estimated from the spread model results and integrated in two regression models together with available data for brado and wild boar populations. There was a significant association between the density of all three populations (domestic pigs, brado, and wild boar) and ASF occurrence in Sardinia. The most significant risk factors were the high densities of brado (OR = 2.2) and wild boar (OR = 2.1). The results of both analyses demonstrated that ASF epidemiology and infection dynamics in Sardinia create a complex and multifactorial disease situation, where all susceptible populations play an important role. To stop ASF transmission in Sardinia, three main factors (improving biosecurity on domestic pig farms, eliminating brado practices and better management of wild boars) need to be addressed.

  12. Glycoproteins identified from heart failure and treatment models.

    PubMed

    Yang, Shuang; Chen, Lijun; Sun, Shisheng; Shah, Punit; Yang, Weiming; Zhang, Bai; Zhang, Zhen; Chan, Daniel W; Kass, David A; van Eyk, Jennifer E; Zhang, Hui

    2015-01-01

    Conduction abnormalities can lead to dyssynchronous contraction, which significantly worsens morbidity and mortality of heart failure. Cardiac resynchronization therapy (CRT) can reverse ventricular remodeling and improve cardiac function. Although the underlying molecular changes are unknown, the use of a canine model of dyssynchronous heart failure (DHF) and CRT has shown that there are global changes across the cardiac proteome. This study determines changes in serum glycoprotein concentration from DHF and CRT compared to normal. We hypothesize that CRT invokes protective or advantageous pathways that can be reflected in the circulating proteome. Two prong discovery approaches were carried out on pooled normal, DHF, and CRT samples composed of individual canine serum to determine the overall protein concentration and the N-linked glycosites of circulating glycoproteins. The level of the glycoproteins was altered in DHF and CRT compared to control sera, with 63 glycopeptides substantially increased in DHF and/or CRT. Among the 32 elevated glycosite-containing peptides in DHF, 13 glycopeptides were reverted to normal level after CRT therapy. We further verify the changes of glycopeptides using label-free LC-MS from individual canine serum. Circulating glycoproteins such as alpha-fetoprotein, alpha-2-macroglobulin, galectin-3-binding protein, and collectin-10 show association to failing heart and CRT treatment model.

  13. Swine in biomedical research. V. 2

    SciTech Connect

    Tumbleson, M.E.

    1986-01-01

    This volume presents information on the following topics: the effect of dietary fiber on growing pigs; preparation of a cerebral perfusion model in the pig - anatomic considerations; a review of the utilization of lactose, glucose, sucrose, and cornstarch by neonatal piglets reared artificially; histology of piglet liver, swine hematology; use of swine as a model of musculoskeletal growth in animals; boar and human sperm as cellular models for membrane phospholipiid biosynthesis and degradation; a stereotaxic atlas of the developing swine (Sus Scrofa) forebrain; the effect of ethanol on liver mitochondrial Ca++-uptake; control of feed intake in pigs; the pig as a model of abberations associated with carbohydrate and lipid metabolism; whey and cholesterol in swine; vitamin and mineral nutrition and malnutrition; cadmium absorption, distribution and excretion in young and adult minature swine; a piglet model for infant total parenteral nutrition studies; swine in perinatal research; the endocrine pancreas of the fetal pig; cardiovascular physiology of the pig fetus; and the effect of sow's milk versus formula on the superior mesenteric blood flow of newborn piglets.

  14. Maternal Malnutrition and Offspring Sex Determine Juvenile Obesity and Metabolic Disorders in a Swine Model of Leptin Resistance

    PubMed Central

    Barbero, Alicia; Astiz, Susana; Lopez-Bote, Clemente J.; Perez-Solana, Maria L.; Ayuso, Miriam; Garcia-Real, Isabel; Gonzalez-Bulnes, Antonio

    2013-01-01

    The present study aimed to determine, in a swine model of leptin resistance, the effects of type and timing of maternal malnutrition on growth patterns, adiposity and metabolic features of the progeny when exposed to an obesogenic diet during their juvenile development and possible concomitant effects of the offspring sex. Thus, four groups were considered. A CONTROL group involved pigs born from sows fed with a diet fulfilling their daily maintenance requirements for pregnancy. The treated groups involved the progeny of females fed with the same diet but fulfilling either 160% or 50% of pregnancy requirements during the entire gestation (OVERFED and UNDERFED, respectively) or 100% of requirements until Day 35 of pregnancy and 50% of such amount from Day 36 onwards (LATE-UNDERFED). OVERFED and UNDERFED offspring were more prone to higher corpulence and fat deposition from early postnatal stages, during breast-feeding; adiposity increased significantly when exposed to obesogenic diets, especially in females. The effects of sex were even more remarkable in LATE-UNDERFED offspring, which had similar corpulence to CONTROL piglets; however, females showed a clear predisposition to obesity. Furthermore, the three groups of pigs with maternal malnutrition showed evidences of metabolic syndrome and, in the case of individuals born from OVERFED sows, even of insulin resistance and the prodrome of type-2 diabetes. These findings support the main role of early nutritional programming in the current rise of obesity and associated diseases in ethnics with leptin resistance. PMID:24205230

  15. Development of a Fatal Noncompressible Truncal Hemorrhage Model with Combined Hepatic and Portal Venous Injury in Normothermic Normovolemic Swine

    PubMed Central

    Yanala, Ujwal R.; Johanning, Jason M.; Pipinos, Iraklis I.; Larsen, Gustavo; Velander, William H.; Carlson, Mark A.

    2014-01-01

    Noncompressible truncal hemorrhage and brain injury currently account for most early mortality of warfighters on the battlefield. There is no effective treatment for noncompressible truncal hemorrhage, other than rapid evacuation to a surgical facility. The availability of an effective field treatment for noncompressible truncal hemorrhage could increase the number of warfighters salvaged from this frequently-lethal scenario. Our intent was to develop a porcine model of noncompressible truncal hemorrhage with a ∼50% one-hour mortality so that we could develop new treatments for this difficult problem. Normovolemic normothermic domestic swine (barrows, 3 months old, 34–36 kg) underwent one of three injury types through a midline incision: 1) central stellate injury (N = 6); 2) excision of a portal vein branch distal to the main PV trunk (N = 6); or 3) hemi-transection of the left lateral lobe of the liver at its base (N = 10). The one-hour mortality of these injuries was 0, 82, and 40%, respectively; the final mean arterial pressure was 65, 24, and 30 mm Hg, respectively; and the final hemoglobin was 8.3, 2.3, and 3.6 g/dL, respectively. Hemi-transection of the left lateral lobe of the liver appeared to target our desired mortality rate better than the other injury mechanisms. PMID:25251401

  16. The Haemophilus ducreyi trimeric autotransporter adhesin DsrA protects against an experimental infection in the swine model of chancroid.

    PubMed

    Fusco, William G; Choudhary, Neelima R; Routh, Patty A; Ventevogel, Melissa S; Smith, Valerie A; Koch, Gary G; Almond, Glen W; Orndorff, Paul E; Sempowski, Gregory D; Leduc, Isabelle

    2014-06-24

    Adherence of pathogens to cellular targets is required to initiate most infections. Defining strategies that interfere with adhesion is therefore important for the development of preventative measures against infectious diseases. As an adhesin to host extracellular matrix proteins and human keratinocytes, the trimeric autotransporter adhesin DsrA, a proven virulence factor of the Gram-negative bacterium Haemophilus ducreyi, is a potential target for vaccine development. A recombinant form of the N-terminal passenger domain of DsrA from H. ducreyi class I strain 35000HP, termed rNT-DsrAI, was tested as a vaccine immunogen in the experimental swine model of H. ducreyi infection. Viable homologous H. ducreyi was not recovered from any animal receiving four doses of rNT-DsrAI administered with Freund's adjuvant at two-week intervals. Control pigs receiving adjuvant only were all infected. All animals receiving the rNT-DsrAI vaccine developed antibody endpoint titers between 3.5 and 5 logs. All rNT-DsrAI antisera bound the surface of the two H. ducreyi strains used to challenge immunized pigs. Purified anti-rNT-DsrAI IgG partially blocked binding of fibrinogen at the surface of viable H. ducreyi. Overall, immunization with the passenger domain of the trimeric autotransporter adhesin DsrA accelerated clearance of H. ducreyi in experimental lesions, possibly by interfering with fibrinogen binding.

  17. Adaptive Failure Compensation for Aircraft Tracking Control Using Engine Differential Based Model

    NASA Technical Reports Server (NTRS)

    Liu, Yu; Tang, Xidong; Tao, Gang; Joshi, Suresh M.

    2006-01-01

    An aircraft model that incorporates independently adjustable engine throttles and ailerons is employed to develop an adaptive control scheme in the presence of actuator failures. This model captures the key features of aircraft flight dynamics when in the engine differential mode. Based on this model an adaptive feedback control scheme for asymptotic state tracking is developed and applied to a transport aircraft model in the presence of two types of failures during operation, rudder failure and aileron failure. Simulation results are presented to demonstrate the adaptive failure compensation scheme.

  18. Failure in laboratory fault models in triaxial tests

    USGS Publications Warehouse

    Savage, J.C.; Lockner, D.A.; Byerlee, J.D.

    1996-01-01

    A model of a fault in the Earth is a sand-filled saw cut in a granite cylinder subjected to a triaxial test. The saw cut is inclined at an angle a to the cylinder axis, and the sand filling is intended to represent gouge. The triaxial test subjects the granite cylinder to a constant confining pressure and increasing axial stress to maintain a constant rate of shortening of the cylinder. The required axial stress increases at a decreasing rate to a maximum, beyond which a roughly constant axial stress is sufficient to maintain the constant rate of shortening: Such triaxial tests were run for saw cuts inclined at angles ?? of 20??, 25??, 30??, 35??, 40??, 45??, and 50?? to the cylinder axis, and the apparent coefficient of friction ??a (ratio of the shear stress to the normal stress, both stresses resolved onto the saw cut) at failure was determined. Subject to the assumption that the observed failure involves slip on Coulomb shears (orientation unspecified), the orientation of the principal compression axis within the gouge can be calculated as a function of ??a for a given value of the coefficient of internal friction ??i. The rotation of the principal stress axes within the gouge in a triaxial test can then be followed as the shear strain across the gouge layer increases. For ??i ??? 0.8, an appropriate value for highly sheared sand, the observed values ??a imply that the principal-axis of compression within the gouge rotates so as to approach being parallel to the cylinder axis for all saw cut angles (20?? < ?? < 50??). In the limiting state (principal compression axis parallel to cylinder axis) the stress state in the gouge layer would be the same as that in the granite cylinder, and the failure criterion would be independent of the saw cut angle.

  19. Spinal Cord Tolerance to Single-Fraction Partial-Volume Irradiation: A Swine Model

    SciTech Connect

    Medin, Paul M.; Foster, Ryan D.; Kogel, Albert J. van der; Sayre, James W.; McBride, William H.; Solberg, Timothy D.

    2011-01-01

    Purpose: To determine the spinal cord tolerance to single-fraction, partial-volume irradiation in swine. Methods and Materials: A 5-cm-long cervical segment was irradiated in 38-47-week-old Yucatan minipigs using a dedicated, image-guided radiosurgery linear accelerator. The radiation was delivered to a cylindrical volume approximately 5 cm in length and 2 cm in diameter that was positioned lateral to the cervical spinal cord, resulting in a dose distribution with the 90%, 50%, and 10% isodose lines traversing the ipsilateral, central, and contralateral spinal cord, respectively. The dose was prescribed to the 90% isodose line. A total of 26 pigs were stratified into eight dose groups of 12-47 Gy. The mean maximum spinal cord dose was 16.9 {+-} 0.1, 18.9 {+-} 0.1, 21.0 {+-} 0.1, 23.0 {+-} 0.2, and 25.3 {+-} 0.3 Gy in the 16-, 18-, 20-, 22-, and 24-Gy dose groups, respectively. The mean percentage of spinal cord volumes receiving {>=}10 Gy for the same groups were 43% {+-} 3%, 48% {+-} 4%, 51% {+-} 2%, 57% {+-} 2%, and 59% {+-} 4%. The study endpoint was motor neurologic deficit determined by a change in gait during a 1-year follow-up period. Results: A steep dose-response curve was observed with a median effective dose for the maximum dose point of 20.0 Gy (95% confidence interval, 18.3-21.7). Excellent agreement was observed between the occurrence of neurologic change and the presence of histologic change. All the minipigs with motor deficits showed some degree of demyelination and focal white matter necrosis on the irradiated side, with relative sparing of the gray matter. The histologic findings were unremarkable in the minipigs with normal neurologic status. Conclusions: Our results have indicated that for a dose distribution with a steep lateral gradient, the pigs had a lower median effective dose for paralysis than has been observed in rats and more closely resembles that for rats, mice, and guinea pigs receiving uniform spinal cord irradiation.

  20. Spinal Cord Tolerance to Reirradiation With Single-Fraction Radiosurgery: A Swine Model

    SciTech Connect

    Medin, Paul M.; Foster, Ryan D.; Kogel, Albert J. van der; Sayre, James W.; McBride, William H.; Solberg, Timothy D.

    2012-07-01

    Purpose: This study was performed to determine swine spinal cord tolerance to single-fraction, partial-volume irradiation 1 year after receiving uniform irradiation to 30 Gy in 10 fractions. Methods and Materials: A 10-cm length of spinal cord (C3-T1) was uniformly irradiated to 30 Gy in 10 consecutive fractions and reirradiated 1 year later with a single radiosurgery dose centered within the previously irradiated segment. Radiosurgery was delivered to a cylindrical volume approximately 5 cm in length and 2 cm in diameter, which was positioned laterally to the cervical spinal cord, resulting in a dose distribution with the 90%, 50%, and 10% isodose lines traversing the ipsilateral, central, and contralateral spinal cord, respectively. Twenty-three pigs were stratified into six dose groups with mean maximum spinal cord doses of 14.9 {+-} 0.1 Gy (n = 2), 17.1 {+-} 0.3 Gy (n = 3), 19.0 {+-} 0.1 Gy (n = 5), 21.2 {+-} 0.1 Gy (n = 5), 23.4 {+-} 0.2 Gy (n = 5), and 25.4 {+-} 0.4 Gy (n = 3). The mean percentage of spinal cord volumes receiving {>=}10 Gy for the same groups were 34% {+-} 1%, 40% {+-} 1%, 46% {+-} 3%, 52% {+-} 1%, 56 {+-} 3%, and 57% {+-} 1%. The study endpoint was motor neurologic deficit as determined by a change in gait during a 1- year follow-up period. Results: A steep dose-response curve was observed with a 50% incidence of paralysis (ED{sub 50}) for the maximum point dose of 19.7 Gy (95% confidence interval, 17.4-21.4). With two exceptions, histology was unremarkable in animals with normal neurologic status, while all animals with motor deficits showed some degree of demyelination and focal white matter necrosis on the irradiated side, with relative sparing of gray matter. Histologic comparison with a companion study of de novo irradiated animals revealed that retreatment responders had more extensive tissue damage, including infarction of gray matter, only at prescription doses >20 Gy. Conclusion: Pigs receiving spinal radiosurgery 1 year after

  1. Predictive influence in the accelerated failure time model.

    PubMed

    Bedrick, Edward J; Exuzides, Alex; Johnson, Wesley O; Thurmond, Mark C

    2002-09-01

    We develop case deletion diagnostics for prediction of future observations in the accelerated failure time model. We view prediction to be an important inferential goal in a survival analysis and thus it is important to identify whether particular observations may be influencing the quality of predictions. We use the Kullback-Leibler divergence as a measure of the discrepancy between the estimated probability distributions for the full and the case-deleted samples. In particular, we focus on the effect of case deletion on estimated survival curves but where we regard the survival curve estimate as a vehicle for prediction. We also develop a diagnostic for assessing the effect of case deletion on inferences for the median time to failure. The estimated median can be used with both predictive and estimative purposes in mind. We also discuss the relationship between our suggested measures and the corresponding Cook distance measure, which was designed with the goal of assessing estimative influence. Several applications of the proposed diagnostics are presented.

  2. Stage Separation Failure: Model Based Diagnostics and Prognostics

    NASA Technical Reports Server (NTRS)

    Luchinsky, Dmitry; Hafiychuk, Vasyl; Kulikov, Igor; Smelyanskiy, Vadim; Patterson-Hine, Ann; Hanson, John; Hill, Ashley

    2010-01-01

    Safety of the next-generation space flight vehicles requires development of an in-flight Failure Detection and Prognostic (FD&P) system. Development of such system is challenging task that involves analysis of many hard hitting engineering problems across the board. In this paper we report progress in the development of FD&P for the re-contact fault between upper stage nozzle and the inter-stage caused by the first stage and upper stage separation failure. A high-fidelity models and analytical estimations are applied to analyze the following sequence of events: (i) structural dynamics of the nozzle extension during the impact; (ii) structural stability of the deformed nozzle in the presence of the pressure and temperature loads induced by the hot gas flow during engine start up; and (iii) the fault induced thrust changes in the steady burning regime. The diagnostic is based on the measurements of the impact torque. The prognostic is based on the analysis of the correlation between the actuator signal and fault-induced changes in the nozzle structural stability and thrust.

  3. Heartbeat Model for Component Failure in Simulation of Plant Behavior

    SciTech Connect

    R. W. Youngblood; R. R. Nourgaliev; D. L. Kelly; C. L. Smith; T-N. Dinh

    2011-03-01

    As part of the Department of Energy’s “Light Water Reactor Sustainability Program” (LWRSP), tools and methodology for risk-informed characterization of safety margin are being developed for use in supporting decision-making on plant life extension after the first license renewal. Beginning with the traditional discussion of “margin” in terms of a “load” (a physical challenge to system or component function) and a “capacity” (the capability of that system or component to accommodate the challenge), we are developing the capability to characterize realistic probabilistic load and capacity spectra, reflecting both aleatory and epistemic uncertainty in system behavior. This way of thinking about margin comports with work done in the last 10 years. However, current capabilities to model in this way are limited: it is currently possible, but difficult, to validly simulate enough time histories to support quantification in realistic problems, and the treatment of environmental influences on reliability is relatively artificial in many existing applications. The INL is working on a next-generation safety analysis capability (widely referred to as “R7”) that will enable a much better integration of reliability-related and phenomenology-related aspects of margin. In this paper, we show how to implement cumulative damage (“heartbeat”) models for component reliability that lend themselves naturally to being included as part of the phenomenology simulation. Implementation of this modeling approach relies on the way in which the phenomenology simulation implements its dynamic time step management. Within this approach, component failures influence the phenomenology, and the phenomenology influences the component failures.

  4. A Macaca mulatta model of fulminant hepatic failure

    PubMed Central

    Zhou, Ping; Xia, Jie; Guo, Gang; Huang, Zi-Xing; Lu, Qiang; Li, Li; Li, Hong-Xia; Shi, Yu-Jun; Bu, Hong

    2012-01-01

    AIM: To establish an appropriate primate model of fulminant hepatic failure (FHF). METHODS: We have, for the first time, established a large animal model of FHF in Macaca mulatta by intraperitoneal infusion of amatoxin and endotoxin. Clinical features, biochemical indexes, histopathology and iconography were examined to dynamically investigate the progress and outcome of the animal model. RESULTS: Our results showed that the enzymes and serum bilirubin were markedly increased and the enzyme-bilirubin segregation emerged 36 h after toxin administration. Coagulation activity was significantly decreased. Gradually deteriorated parenchymal abnormality was detected by magnetic resonance imaging (MRI) and ultrasonography at 48 h. The liver biopsy showed marked hepatocyte steatosis and massive parenchymal necrosis at 36 h and 49 h, respectively. The autopsy showed typical yellow atrophy of the liver. Hepatic encephalopathy of the models was also confirmed by hepatic coma, MRI and pathological changes of cerebral edema. The lethal effects of the extrahepatic organ dysfunction were ruled out by their biochemical indices, imaging and histopathology. CONCLUSION: We have established an appropriate large primate model of FHF, which is closely similar to clinic cases, and can be used for investigation of the mechanism of FHF and for evaluation of potential medical therapies. PMID:22346249

  5. Evaluation of a Multi-Axial, Temperature, and Time Dependent (MATT) Failure Model

    NASA Technical Reports Server (NTRS)

    Richardson, D. E.; Anderson, G. L.; Macon, D. J.; Rudolphi, Michael (Technical Monitor)

    2002-01-01

    To obtain a better understanding the response of the structural adhesives used in the Space Shuttle's Reusable Solid Rocket Motor (RSRM) nozzle, an extensive effort has been conducted to characterize in detail the failure properties of these adhesives. This effort involved the development of a failure model that includes the effects of multi-axial loading, temperature, and time. An understanding of the effects of these parameters on the failure of the adhesive is crucial to the understanding and prediction of the safety of the RSRM nozzle. This paper documents the use of this newly developed multi-axial, temperature, and time (MATT) dependent failure model for modeling failure for the adhesives TIGA 321, EA913NA, and EA946. The development of the mathematical failure model using constant load rate normal and shear test data is presented. Verification of the accuracy of the failure model is shown through comparisons between predictions and measured creep and multi-axial failure data. The verification indicates that the failure model performs well for a wide range of conditions (loading, temperature, and time) for the three adhesives. The failure criterion is shown to be accurate through the glass transition for the adhesive EA946. Though this failure model has been developed and evaluated with adhesives, the concepts are applicable for other isotropic materials.

  6. Failure Analysis of Nonvolatile Residue (NVR) Analyzer Model SP-1000

    NASA Technical Reports Server (NTRS)

    Potter, Joseph C.

    2011-01-01

    National Aeronautics and Space Administration (NASA) subcontractor Wiltech contacted the NASA Electrical Lab (NE-L) and requested a failure analysis of a Solvent Purity Meter; model SP-IOOO produced by the VerTis Instrument Company. The meter, used to measure the contaminate in a solvent to determine the relative contamination on spacecraft flight hardware and ground servicing equipment, had been inoperable and in storage for an unknown amount of time. NE-L was asked to troubleshoot the unit and make a determination on what may be required to make the unit operational. Through the use of general troubleshooting processes and the review of a unit in service at the time of analysis, the unit was found to be repairable but would need the replacement of multiple components.

  7. Modeling cascading failures in the North American power grid

    NASA Astrophysics Data System (ADS)

    Kinney, R.; Crucitti, P.; Albert, R.; Latora, V.

    2005-07-01

    The North American power grid is one of the most complex technological networks, and its interconnectivity allows both for long-distance power transmission and for the propagation of disturbances. We model the power grid using its actual topology and plausible assumptions about the load and overload of transmission substations. Our results indicate that the loss of a single substation can result in up to 25% loss of transmission efficiency by triggering an overload cascade in the network. The actual transmission loss depends on the overload tolerance of the network and the connectivity of the failed substation. We systematically study the damage inflicted by the loss of single nodes, and find three universal behaviors, suggesting that 40% of the transmission substations lead to cascading failures when disrupted. While the loss of a single node can inflict substantial damage, subsequent removals have only incremental effects, in agreement with the topological resilience to less than 1% node loss.

  8. Enalapril protects against myocardial ischemia/reperfusion injury in a swine model of cardiac arrest and resuscitation

    PubMed Central

    Wang, Guoxing; Zhang, Qian; Yuan, Wei; Wu, Junyuan; Li, Chunsheng

    2016-01-01

    There is strong evidence to suggest that angiotensin-converting enzyme inhibitors (ACEIs) protect against local myocardial ischemia/reperfusion (I/R) injury. This study was designed to explore whether ACEIs exert cardioprotective effects in a swine model of cardiac arrest (CA) and resuscitation. Male pigs were randomly assigned to three groups: sham-operated group, saline treatment group and enalapril treatment group. Thirty minutes after drug infusion, the animals in the saline and enalapril groups were subjected to ventricular fibrillation (8 min) followed by cardiopulmonary resuscitation (up to 30 min). Cardiac function was monitored, and myocardial tissue and blood were collected for analysis. Enalapril pre-treatment did not improve cardiac function or the 6-h survival rate after CA and resuscitation; however, this intervention ameliorated myocardial ultrastructural damage, reduced the level of plasma cardiac troponin I and decreased myocardial apoptosis. Plasma angiotensin (Ang) II and Ang-(1–7) levels were enhanced in the model of CA and resuscitation. Enalapril reduced the plasma Ang II level at 4 and 6 h after the return of spontaneous circulation whereas enalapril did not affect the plasma Ang-(1–7) level. Enalapril pre-treatment decreased the myocardial mRNA and protein expression of angiotensin-converting enzyme (ACE). Enalapril treatment also reduced the myocardial ACE/ACE2 ratio, both at the mRNA and the protein level. Enalapril pre-treatment did not affect the upregulation of ACE2, Ang II type 1 receptor (AT1R) and MAS after CA and resuscitation. Taken together, these findings suggest that enalapril protects against ischemic injury through the attenuation of the ACE/Ang II/AT1R axis after CA and resuscitation in pigs. These results suggest the potential therapeutic value of ACEIs in patients with CA. PMID:27633002

  9. Evaluation of ammonium adsorption in biochar-fixed beds for treatment of anaerobically digested swine slurry: Experimental optimization and modeling.

    PubMed

    Kizito, Simon; Wu, Shubiao; Wandera, Simon Mdondo; Guo, Luchen; Dong, Renjie

    2016-09-01

    Fixed-bed column experiments were performed to investigate the effect of influent concentration, flow rate, and adsorbent bed depth on ammonium adsorption from anaerobically digested swine slurry using three types of biochar made from corncobs (MCB), hardwood (WB), and mixed sawdust pellets (MSB). WB performed better than the other two biochar types with a maximum sorption capacity of 67-114mg/g due to its superior surface area and larger pore volume. Ammonium adsorption kinetics and dynamics depended on the influent NH4(+)-N concentration, applied inflow flow rate, and the depth of the fixed bed. Maximum sorption capacities under influent NH4(+)-N concentration of 500mg/L, were identified to be 114.2mg/g, 108.9mg/g, and 24.7mg/g at inflow rate of 15mL/min for WB, MCB, and MSB, respectively. The data shows that using deeper beds and applying lower flow rates could be a better strategy to increase ammonium adsorption in biochar-fixed beds. Moreover, three kinetic models (Thomas, Adams-Bohart (BDST), and Yoon-Nelson) were applied to the experimental data to predict breakthrough curves and determine characteristic adsorption parameters for process design. The applied models fitted data in the order: Thomas (R(2)=0.971)>BDST (R(2)=0.960)>Yoon-Nelson (R(2)=0.940). It was concluded that ammonium adsorption in biochar-fixed beds could be an effective method for routine cyclic treatment of slurry. However, further effluent polishing is required to meet discharge requirements.

  10. Agent autonomy approach to probabilistic physics-of-failure modeling of complex dynamic systems with interacting failure mechanisms

    NASA Astrophysics Data System (ADS)

    Gromek, Katherine Emily

    A novel computational and inference framework of the physics-of-failure (PoF) reliability modeling for complex dynamic systems has been established in this research. The PoF-based reliability models are used to perform a real time simulation of system failure processes, so that the system level reliability modeling would constitute inferences from checking the status of component level reliability at any given time. The "agent autonomy" concept is applied as a solution method for the system-level probabilistic PoF-based (i.e. PPoF-based) modeling. This concept originated from artificial intelligence (AI) as a leading intelligent computational inference in modeling of multi agents systems (MAS). The concept of agent autonomy in the context of reliability modeling was first proposed by M. Azarkhail [1], where a fundamentally new idea of system representation by autonomous intelligent agents for the purpose of reliability modeling was introduced. Contribution of the current work lies in the further development of the agent anatomy concept, particularly the refined agent classification within the scope of the PoF-based system reliability modeling, new approaches to the learning and the autonomy properties of the intelligent agents, and modeling interacting failure mechanisms within the dynamic engineering system. The autonomous property of intelligent agents is defined as agent's ability to self-activate, deactivate or completely redefine their role in the analysis. This property of agents and the ability to model interacting failure mechanisms of the system elements makes the agent autonomy fundamentally different from all existing methods of probabilistic PoF-based reliability modeling. 1. Azarkhail, M., "Agent Autonomy Approach to Physics-Based Reliability Modeling of Structures and Mechanical Systems", PhD thesis, University of Maryland, College Park, 2007.

  11. A Dynamic Approach to Modeling Dependence Between Human Failure Events

    SciTech Connect

    Boring, Ronald Laurids

    2015-09-01

    In practice, most HRA methods use direct dependence from THERP—the notion that error be- gets error, and one human failure event (HFE) may increase the likelihood of subsequent HFEs. In this paper, we approach dependence from a simulation perspective in which the effects of human errors are dynamically modeled. There are three key concepts that play into this modeling: (1) Errors are driven by performance shaping factors (PSFs). In this context, the error propagation is not a result of the presence of an HFE yielding overall increases in subsequent HFEs. Rather, it is shared PSFs that cause dependence. (2) PSFs have qualities of lag and latency. These two qualities are not currently considered in HRA methods that use PSFs. Yet, to model the effects of PSFs, it is not simply a matter of identifying the discrete effects of a particular PSF on performance. The effects of PSFs must be considered temporally, as the PSFs will have a range of effects across the event sequence. (3) Finally, there is the concept of error spilling. When PSFs are activated, they not only have temporal effects but also lateral effects on other PSFs, leading to emergent errors. This paper presents the framework for tying together these dynamic dependence concepts.

  12. Fulminant liver failure model with hepatic encephalopathy in the mouse

    PubMed Central

    Hori, Tomohide; Chen, Feng; Baine, Ann-Marie T.; Gardner, Lindsay B.; Nguyen, Justin H.

    2011-01-01

    Aim To develop a reliable murine model for fulminant liver failure (FLF). Material and Methods We treated three groups of male C57BL/6 mice:as controls, with azoxymethane (AOM), and with galactosamine (Gal) and tumor necrosis factor-alpha (TNFα). Effects of body temperature (BT) control on survival, in all three groups were investigated. Using BT control, survival, histopathological findings and biochemical/coagulation profiles were compared between the experimental groups. Effects of hydration on international normalized ratios of prothrombin time (PT-INR) were also checked. Dose-dependent survival curves were made for both experimental groups. Neurological behaviors were assessed using a coma scale. Results No unexpected BT effects were seen in the control group. The AOM group, but not the Gal+TNFα group, showed significant differences in survival curves between those with and without BT care. Histopathological assessment showed consistent FLF findings in both experimental groups with BT care. Between the experimental groups, there were significant differences in aspartate aminotransferase levels and PT-INR; and significant differences in PT-INRs between sufficiently- and insufficiently-hydrated groups. There were significant differences between FLF models, in the duration of each coma stage, with significant differences in stages 1 and 3 as percentages of the diseased state (stages 1-4). The two FLF models with BT care showed different survival curves in the dose-dependent survival study. Conclusion Azoxymethane can provide a good FLF model, but requires a specialized environment and careful BT control. Other FLF models may also be useful, depending on research purpose. Thoughtful attention to caregiving and close observation are indispensable for successful FLF models. PMID:24713795

  13. Phase field modeling of the defect evolution and failure

    NASA Astrophysics Data System (ADS)

    Xie, Yuesong

    The plastic recovery processes in ultrafine and nano grained metals and the yield criteria and failure mechanisms in polymer matrix composite are the two major topics in this work. In the first part of the work, a phase field dislocation dynamics (PFDD) approach is introduced, which tracks the evolution of the dislocations in ultrafine and nano grained metals and takes into account the elastic interaction between dislocations, obstacles and the applied resolved shear stress on a single slip plane. Two phenomena, the reverse plastic strain during cyclic loading and plastic strain recovery upon unloading, are studied. One major finding of our simulations is that these two plastic recovery processes are related to the formation of dislocation structures during loading, and additional grain size inhomogeneity will increase the amount of plastic strain recovered. In the second part of the work, a phase field damage model (PFDM) is presented to study the onset of yielding and crack propagation in polymer matrix composite. The effect of two damage parameters, the fracture toughness Gc and crack length scale parameter l0, are first investigated. The former is shown to determine the energy needed during crack propagation and the latter is observed to control the crack nucleation process. Moreover, two asymmetric damage models are compared regarding their yield surfaces and it is found that the model of Miehe et al. leads to a linear pressure modified von Mises relation. Next, the PFDM reveals that the yield criterion in amorphous polymers should be described in terms of local stress and strains fields and cannot be extended directly from applied stress field values. Furthermore, it is demonstrated that the same damage model can be used to study the failure under shear yielding and crazing conditions. And if local defects in the samples such as voids are included explicitly in the simulations, the PFDM is able to explain the breakdown of the pressure modified von Mises

  14. Evaluation of a Linear Cumulative Damage Failure Model for Epoxy Adhesive

    NASA Technical Reports Server (NTRS)

    Richardson, David E.; Batista-Rodriquez, Alicia; Macon, David; Totman, Peter; McCool, Alex (Technical Monitor)

    2001-01-01

    Recently a significant amount of work has been conducted to provide more complex and accurate material models for use in the evaluation of adhesive bondlines. Some of this has been prompted by recent studies into the effects of residual stresses on the integrity of bondlines. Several techniques have been developed for the analysis of bondline residual stresses. Key to these analyses is the criterion that is used for predicting failure. Residual stress loading of an adhesive bondline can occur over the life of the component. For many bonded systems, this can be several years. It is impractical to directly characterize failure of adhesive bondlines under a constant load for several years. Therefore, alternative approaches for predictions of bondline failures are required. In the past, cumulative damage failure models have been developed. These models have ranged from very simple to very complex. This paper documents the generation and evaluation of some of the most simple linear damage accumulation tensile failure models for an epoxy adhesive. This paper shows how several variations on the failure model were generated and presents an evaluation of the accuracy of these failure models in predicting creep failure of the adhesive. The paper shows that a simple failure model can be generated from short-term failure data for accurate predictions of long-term adhesive performance.

  15. Transmission parameters estimated for Salmonella typhimurium in swine using susceptible-infectious-resistant models and a Bayesian approach

    PubMed Central

    2014-01-01

    Background Transmission models can aid understanding of disease dynamics and are useful in testing the efficiency of control measures. The aim of this study was to formulate an appropriate stochastic Susceptible-Infectious-Resistant/Carrier (SIR) model for Salmonella Typhimurium in pigs and thus estimate the transmission parameters between states. Results The transmission parameters were estimated using data from a longitudinal study of three Danish farrow-to-finish pig herds known to be infected. A Bayesian model framework was proposed, which comprised Binomial components for the transition from susceptible to infectious and from infectious to carrier; and a Poisson component for carrier to infectious. Cohort random effects were incorporated into these models to allow for unobserved cohort-specific variables as well as unobserved sources of transmission, thus enabling a more realistic estimation of the transmission parameters. In the case of the transition from susceptible to infectious, the cohort random effects were also time varying. The number of infectious pigs not detected by the parallel testing was treated as unknown, and the probability of non-detection was estimated using information about the sensitivity and specificity of the bacteriological and serological tests. The estimate of the transmission rate from susceptible to infectious was 0.33 [0.06, 1.52], from infectious to carrier was 0.18 [0.14, 0.23] and from carrier to infectious was 0.01 [0.0001, 0.04]. The estimate for the basic reproduction ration (R 0 ) was 1.91 [0.78, 5.24]. The probability of non-detection was estimated to be 0.18 [0.12, 0.25]. Conclusions The proposed framework for stochastic SIR models was successfully implemented to estimate transmission rate parameters for Salmonella Typhimurium in swine field data. R 0 was 1.91, implying that there was dissemination of the infection within pigs of the same cohort. There was significant temporal-cohort variability, especially at the

  16. Prenatal programming of obesity in a swine model of leptin resistance: modulatory effects of controlled postnatal nutrition and exercise.

    PubMed

    Barbero, A; Astiz, S; Ovilo, C; Lopez-Bote, C J; Perez-Solana, M L; Ayuso, M; Garcia-Real, I; Gonzalez-Bulnes, A

    2014-06-01

    The main role of early nutritional programming in the current rise of obesity and associated diseases is well known. However, translational studies are mostly based in postnatal food excess and, thus, there is a paucity of information on the phenotype of individuals with prenatal deficiencies but adequate postnatal conditions. Thus, we assessed the effects of prenatal programming (comparing descendants from females fed with a diet fulfilling 100 or only 50% of their nutritional requirements for pregnancy) on gene expression, patterns of growth and fattening, metabolic status and puberty attainment of a swine model of obesity/leptin resistance with controlled postnatal nutrition and opportunity of exercise. Maternal restriction was related to changes in the relationships among gene expression of positive (insulin-like growth factors 1 and 2) and negative (myostatin) regulators of muscle growth, with negative correlations in gilts from restricted pregnancies and positive relationships in the control group. In spite of these differences, the patterns of growth and fattening and the metabolic features during juvenile growth were similar in control gilts and gilts from restricted pregnancies. Concomitantly, there was a lack of differences in the timing of puberty attainment. However, after reaching puberty and adulthood, females from restricted pregnancies were heavier and more corpulent than control gilts, though such increases in weight and size were not accompanied by increases in adiposity. In conclusion, in spite of changes in gene expression induced by developmental programming, the propensity for higher weight and adiposity of individuals exposed to prenatal malnutrition may be modulated by controlled food intake and opportunity of physical exercise during infant and juvenile development.

  17. Snatch-farrowed, porcine-colostrum-deprived (SF-pCD) pigs as a model for swine infectious disease research

    PubMed Central

    Huang, Yanyun; Haines, Deborah M.; Harding, John C.S.

    2013-01-01

    The current study tested the benefit of commercially available spray-dried bovine colostrum (The Saskatoon Colostrum Company, Saskatoon, Saskatchewan) in raising snatch-farrowed, porcine-colostrum-deprived (SF-pCD) pigs. In experiment 1, 12 SF-pCD pigs received a liquid diet composed mainly of bovine colostrum from birth to day 10; 6 remained on the same liquid diet (COL), and the other 6 were fed a diet composed mainly of milk replacer (RPL) until weaning. In experiment 2, 12 SF-pCD pigs were fed mainly bovine colostrum before weaning; after weaning, 6 were fed a starter diet containing 20% (w/w) bovine colostrum powder (STARTER-COL), and the other 6 were fed a starter diet without any bovine colostrum (STARTER-CTRL) until termination (day 42 or day 49). In experiment 1 the COL pigs had significantly fewer fever-days than did the RPL pigs. In experiment 2 diarrhea, typhlocolitis, and pancreatic degeneration developed in 4 of the STARTER-COL pigs after weaning. In both experiments all the pigs fed mainly bovine colostrum before weaning survived until termination. All pigs tested free of swine influenza virus H1N1 and H3N2, Porcine reproductive and respiratory syndrome virus, and Porcine parvovirus. In experiment 2 all the pigs tested free of Porcine circovirus type 2 (PCV2), but some in both groups tested positive for Torque teno virus genogroups 1 and 2. In conclusion, with the use of snatch-farrowing and bovine colostrum, pigs can be raised in the absence of porcine maternal antibodies with 100% survival and freedom from most porcine pathogens of biologic relevance. This model is potentially suitable for animal disease research. PMID:24082397

  18. Improved bleeding scores using Gelfoam(®) Powder with incremental concentrations of bovine thrombin in a swine liver lesion model.

    PubMed

    Morse, Dennis C; Silva, Elif; Bartrom, Jolee; Young, Kelli; Bass, Eric J; Potter, David; Bieber, Trevor

    2016-10-01

    Topical hemostatic agents are used intra-operatively to prevent uncontrolled bleeding. Gelfoam(®) Powder contains a hemostatic agent prepared from purified pork skin gelatin, the efficacy of which is increased when combined with thrombin. However, the effect of increasing concentrations of thrombin on resultant hemostasis is not known. This study sought to evaluate the ability of various concentrations of thrombin in combination with Gelfoam Powder to control bleeding using a swine liver lesion model. Ten pigs underwent a midline laparotomy. Circular lesions were created in the left medial, right medial, and left lateral lobes; six lesions per lobe. Gelfoam Powder was hydrated with Thrombin-JMI(®) diluted to 250, 375, and 770 IU/mL. Each concentration was applied to two lesion sites per lobe. Bleeding scores were measured at 3, 6, 9, and 12 min using a 6-point system; comparison of bleeding scores was performed using ANOVA with the post hoc Tukey test. The bleeding scores with thrombin concentrations at 770 IU/mL were significantly lower than at 250 and 375 IU/mL at all four time points. The percentage of biopsies with a clinically acceptable bleeding score rose from 37.9, 46.6, and 71.2 % at 3 min to 55.2, 69.0, and 88.1 % at 12 min in the 250, 375, and 770 IU/mL thrombin groups, respectively. The study showed that the hemostatic response to thrombin was dose-related: using higher concentrations of thrombin with Gelfoam Powder yielded improved hemostasis, as determined by lower bleeding scores.

  19. Intracoronary Delivery of Human Mesenchymal/Stromal Stem Cells: Insights from Coronary Microcirculation Invasive Assessment in a Swine Model

    PubMed Central

    Fiarresga, António; Mata, Márcia F.; Cavaco-Gonçalves, Sandra; Selas, Mafalda; Simões, Irina N.; Oliveira, Eunice; Carrapiço, Belmira; Cardim, Nuno; Cabral, Joaquim M. S.; Ferreira, Rui Cruz; da Silva, Cláudia L.

    2015-01-01

    Background Mesenchymal stem/stromal cells have unique properties favorable to their use in clinical practice and have been studied for cardiac repair. However, these cells are larger than coronary microvessels and there is controversy about the risk of embolization and microinfarctions, which could jeopardize the safety and efficacy of intracoronary route for their delivery. The index of microcirculatory resistance (IMR) is an invasive method for quantitatively assessing the coronary microcirculation status. Objectives To examine heart microcirculation after intracoronary injection of mesenchymal stem/stromal cells with the index of microcirculatory resistance. Methods Healthy swine were randomized to receive by intracoronary route either 30x106 MSC or the same solution with no cells (1% human albumin/PBS) (placebo). Blinded operators took coronary pressure and flow measurements, prior to intracoronary infusion and at 5 and 30 minutes post-delivery. Coronary flow reserve (CFR) and the IMR were compared between groups. Results CFR and IMR were done with a variance within the 3 transit time measurements of 6% at rest and 11% at maximal hyperemia. After intracoronary infusion there were no significant differences in CFR. The IMR was significantly higher in MSC-injected animals (at 30 minutes, 14.2U vs. 8.8U, p = 0.02) and intragroup analysis showed a significant increase of 112% from baseline to 30 minutes after cell infusion, although no electrocardiographic changes or clinical deterioration were noted. Conclusion Overall, this study provides definitive evidence of microcirculatory disruption upon intracoronary administration of mesenchymal stem/stromal cells, in a large animal model closely resembling human cardiac physiology, function and anatomy. PMID:26479722

  20. Differential effects of octanoate and heptanoate on myocardial metabolism during extracorporeal membrane oxygenation in an infant swine model

    PubMed Central

    Kajimoto, Masaki; Ledee, Dolena R.; Olson, Aaron K.; Isern, Nancy G.; Des Rosiers, Christine

    2015-01-01

    Nutritional energy support during extracorporeal membrane oxygenation (ECMO) should promote successful myocardial adaptation and eventual weaning from the ECMO circuit. Fatty acids (FAs) are a major myocardial energy source, and medium-chain FAs (MCFAs) are easily taken up by cell and mitochondria without membrane transporters. Odd-numbered MCFAs supply carbons to the citric acid cycle (CAC) via anaplerotic propionyl-CoA as well as acetyl-CoA, the predominant β-oxidation product for even-numbered MCFA. Theoretically, this anaplerotic pathway enhances carbon entry into the CAC, and provides superior energy state and preservation of protein synthesis. We tested this hypothesis in an immature swine model undergoing ECMO. Fifteen male Yorkshire pigs (26–45 days old) with 8-h ECMO received either normal saline, heptanoate (odd-numbered MCFA), or octanoate (even-numbered MCFA) at 2.3 μmol·kg body wt−1·min−1 as MCFAs systemically during ECMO (n = 5/group). The 13-carbon (13C)-labeled substrates ([2-13C]lactate, [5,6,7-13C3]heptanoate, and [U-13C6]leucine) were systemically infused as metabolic markers for the final 60 min before left ventricular tissue extraction. Extracted tissues were analyzed for the 13C-labeled and absolute concentrations of metabolites by nuclear magnetic resonance and gas chromatography-mass spectrometry. Octanoate produced markedly higher myocardial citrate concentration, and led to a higher [ATP]-to-[ADP] ratio compared with other groups. Unexpectedly, octanoate and heptanoate increased the flux of propionyl-CoA relative to acetyl-CoA into the CAC compared with control. MCFAs promoted increases in leucine oxidation, but were not associated with a difference in protein synthesis rate. In conclusion, octanoate provides energetic advantages to the heart over heptanoate. PMID:26232235

  1. Differential Effects Of Octanoate And Heptanoate On Myocardial Metabolism During Extracorporeal Membrane Oxygenation In An Infant Swine Model

    SciTech Connect

    Kajimoto, Masaki; Ledee, Dolena R.; Isern, Nancy G.; Olson, Aaron; Des Rosiers, Christine; Portman, Michael A.

    2015-10-01

    Background: Nutritional energy support during extracorporeal membrane oxygenation (ECMO) should promote successful myocardial adaptation and eventual weaning from the ECMO circuit. Fatty acids (FAs) are a major myocardial energy source, and medium-chain FAs (MCFAs) are easily taken up by cell and mitochondria without membrane transporters. Oddnumbered MCFAs supply carbons to the citric acid cycle (CAC) via anaplerotic propionyl-CoA as well as acetyl-CoA, the predominant betaoxidation product for even-numbered MCFA. Theoretically, this anaplerotic pathway enhances carbon entry into the CAC, and provides superior energy state and preservation of protein synthesis. We tested this hypothesis in an immature swine model undergoing ECMO. Methods: Fifteen male Yorkshire pigs (26-45 days old) with 8-hour ECMO were received either normal saline, heptanoate (odd-numbered MCFA) or octanoate (even-numbered MCFA) at 2.3 μmol/kg body wt/min as MCFAs systemically during ECMO (n = 5 per group). The 13-Carbon (13C)-labeled substrates ([2-13C]lactate, [5,6,7-13C3]heptanoate and [U-13C6]leucine) were systemically infused as metabolic markers for the final 60 minutes before left ventricular tissue extraction. Extracted tissues were analyzed for the 13C-labeled and absolute concentrations of metabolites by nuclear magnetic resonance and gas chromatography-mass spectrometry. Results: Octanoate produced markedly higher myocardial citrate concentration, and led to a higher [ATP]/[ADP] ratio compared with other http://mc.manuscriptcentral.com/jpen Journal of Parenteral and Enteral Nutrition For Peer Review groups. Unexpectedly, octanoate increased the flux of propionyl-CoA relative to acetyl-CoA into the CAC as well as heptanoate. MCFAs promoted increases in leucine oxidation, but were not associated with a difference in fractional protein synthesis rate. Conclusion: Octanoate provides energetic advantages to the heart over heptanoate, while preserving protein synthesis.

  2. An introductory characterization of a combat-casualty-care relevant swine model of closed head injury resulting from exposure to explosive blast.

    PubMed

    Bauman, Richard A; Ling, Geoffrey; Tong, Lawrence; Januszkiewicz, Adolph; Agoston, Dennis; Delanerolle, Nihal; Kim, Young; Ritzel, Dave; Bell, Randy; Ecklund, James; Armonda, Rocco; Bandak, Faris; Parks, Steven

    2009-06-01

    Explosive blast has been extensively used as a tactical weapon in Operation Iraqi Freedom (OIF) and more recently in Operation Enduring Freedom(OEF). The polytraumatic nature of blast injuries is evidence of their effectiveness,and brain injury is a frequent and debilitating form of this trauma. In-theater clinical observations of brain-injured casualties have shown that edema, intracranial hemorrhage, and vasospasm are the most salient pathophysiological characteristics of blast injury to the brain. Unfortunately, little is known about exactly how an explosion produces these sequelae as well as others that are less well documented. Consequently, the principal objective of the current report is to present a swine model of explosive blast injury to the brain. This model was developed during Phase I of the DARPA (Defense Advanced Research Projects Agency) PREVENT (Preventing Violent Explosive Neurotrauma) blast research program. A second objective is to present data that illustrate the capabilities of this model to study the proximal biomechanical causes and the resulting pathophysiological, biochemical,neuropathological, and neurological consequences of explosive blast injury to the swine brain. In the concluding section of this article, the advantages and limitations of the model are considered, explosive and air-overpressure models are compared, and the physical properties of an explosion are identified that potentially contributed to the in-theater closed head injuries resulting from explosions of improvised explosive devices (IEDs).

  3. Life Prediction and Classification of Failure Modes in Solid State Luminaires Using Bayesian Probabilistic Models

    SciTech Connect

    Lall, Pradeep; Wei, Junchao; Sakalaukus, Peter

    2014-05-27

    A new method has been developed for assessment of the onset of degradation in solid state luminaires to classify failure mechanisms by using metrics beyond lumen degradation that are currently used for identification of failure. Luminous Flux output, Correlated Color Temperature Data on Philips LED Lamps has been gathered under 85°C/85%RH till lamp failure. The acquired data has been used in conjunction with Bayesian Probabilistic Models to identify luminaires with onset of degradation much prior to failure through identification of decision boundaries between lamps with accrued damage and lamps beyond the failure threshold in the feature space. In addition luminaires with different failure modes have been classified separately from healthy pristine luminaires. It is expected that, the new test technique will allow the development of failure distributions without testing till L70 life for the manifestation of failure.

  4. DISTRIBUTED CONTAINER FAILURE MODELS FOR THE DUST-MS COMPUTER CODE.

    SciTech Connect

    SULLIVAN,T.; DE LEMOS,F.

    2001-02-24

    Improvements to the DUST-MS computer code have been made that permit simulation of distributed container failure rates. The new models permit instant failure of all containers within a computational volume, uniform failure of these containers over time, or a normal distribution in container failures. Incorporation of a distributed failure model requires wasteform releases to be calculated using a convolution integral. In addition, the models permit a unique time of emplacement for each modeled container and allow a fraction of the containers to fail at emplacement. Implementation of these models, verification testing, and an example problem comparing releases from a wasteform with a two-species decay chain as a function of failure distribution are presented in the paper.

  5. A zipper network model of the failure mechanics of extracellular matrices.

    PubMed

    Ritter, Michael C; Jesudason, Rajiv; Majumdar, Arnab; Stamenovic, Dimitrije; Buczek-Thomas, Jo Ann; Stone, Phillip J; Nugent, Matthew A; Suki, Béla

    2009-01-27

    Mechanical failure of soft tissues is characteristic of life-threatening diseases, including capillary stress failure, pulmonary emphysema, and vessel wall aneurysms. Failure occurs when mechanical forces are sufficiently high to rupture the enzymatically weakened extracellular matrix (ECM). Elastin, an important structural ECM protein, is known to stretch beyond 200% strain before failing. However, ECM constructs and native vessel walls composed primarily of elastin and proteoglycans (PGs) have been found to fail at much lower strains. In this study, we hypothesized that PGs significantly contribute to tissue failure. To test this, we developed a zipper network model (ZNM), in which springs representing elastin are organized into long wavy fibers in a zipper-like formation and placed within a network of springs mimicking PGs. Elastin and PG springs possessed distinct mechanical and failure properties. Simulations using the ZNM showed that the failure of PGs alone reduces the global failure strain of the ECM well below that of elastin, and hence, digestion of elastin does not influence the failure strain. Network analysis suggested that whereas PGs drive the failure process and define the failure strain, elastin determines the peak and failure stresses. Predictions of the ZNM were experimentally confirmed by measuring the failure properties of engineered elastin-rich ECM constructs before and after digestion with trypsin, which cleaves the core protein of PGs without affecting elastin. This study reveals a role for PGs in the failure properties of engineered and native ECM with implications for the design of engineered tissues.

  6. Modelling the transmission dynamics and control of the novel 2009 swine influenza (H1N1) pandemic.

    PubMed

    Sharomi, O; Podder, C N; Gumel, A B; Mahmud, S M; Rubinstein, E

    2011-03-01

    The paper presents a deterministic compartmental model for the transmission dynamics of swine influenza (H1N1) pandemic in a population in the presence of an imperfect vaccine and use of drug therapy for confirmed cases. Rigorous analysis of the model, which stratifies the infected population in terms of their risk of developing severe illness, reveals that it exhibits a vaccine-induced backward bifurcation when the associated reproduction number is less than unity. The epidemiological consequence of this result is that the effective control of H1N1, when the reproduction number is less than unity, in the population would then be dependent on the initial sizes of the subpopulations of the model. For the case where the vaccine is perfect, it is shown that having the reproduction number less than unity is necessary and sufficient for effective control of H1N1 in the population (in such a case, the associated disease-free equilibrium is globally asymptotically stable). The model has a unique endemic equilibrium when the reproduction number exceeds unity. Numerical simulations of the model, using data relevant to the province of Manitoba, Canada, show that it reasonably mimics the observed H1N1 pandemic data for Manitoba during the first (Spring) wave of the pandemic. Further, it is shown that the timely implementation of a mass vaccination program together with the size of the Manitoban population that have preexisting infection-acquired immunity (from the first wave) are crucial to the magnitude of the expected burden of disease associated with the second wave of the H1N1 pandemic. With an estimated vaccine efficacy of approximately 80%, it is projected that at least 60% of Manitobans need to be vaccinated in order for the effective control or elimination of the H1N1 pandemic in the province to be feasible. Finally, it is shown that the burden of the second wave of H1N1 is expected to be at least three times that of the first wave, and that the second wave would last

  7. Swine immune system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Probably no area of veterinary medicine has seen a greater explosion in knowledge then the immune system and its implications in disease and vaccination. In this chapter on the Swine Immune System for the 10th Edition of Diseases of Swine we expand on the information provided in past editions by in...

  8. Draft genome sequence of the Bordetella bronchiseptica swine isolate KM22

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bordetella bronchiseptica swine isolate KM22 has been used in experimental infections of swine as a model of clinical B. bronchiseptica infections within swine herds and to study host-to-host transmission. Here we report the draft genome sequence of KM22....

  9. Stochastic spatio-temporal modelling of African swine fever spread in the European Union during the high risk period.

    PubMed

    Nigsch, Annette; Costard, Solenne; Jones, Bryony A; Pfeiffer, Dirk U; Wieland, Barbara

    2013-03-01

    African swine fever (ASF) is a notifiable viral pig disease with high mortality and serious socio-economic consequences. Since ASF emerged in Georgia in 2007 the disease has spread to several neighbouring countries and cases have been detected in areas bordering the European Union (EU). It is uncertain how fast the virus would be able to spread within the unrestricted European trading area if it were introduced into the EU. This project therefore aimed to develop a model for the spread of ASF within and between the 27 Member States (MS) of the EU during the high risk period (HRP) and to identify MS during that period would most likely contribute to ASF spread ("super-spreaders") or MS that would most likely receive cases from other MS ("super-receivers"). A stochastic spatio-temporal state-transition model using simulated individual farm records was developed to assess silent ASF virus spread during different predefined HRPs of 10-60 days duration. Infection was seeded into farms of different pig production types in each of the 27 MS. Direct pig-to-pig transmission and indirect transmission routes (pig transport lorries and professional contacts) were considered the main pathways during the early stages of an epidemic. The model was parameterised using data collated from EUROSTAT, TRACES, a questionnaire sent to MS, and the scientific literature. Model outputs showed that virus circulation was generally limited to 1-2 infected premises per outbreak (95% IQR: 1-4; maximum: 10) with large breeder farms as index case resulting in most infected premises. Seven MS caused between-MS spread due to intra-Community trade during the first 10 days after seeding infection. For a HRP of 60 days from virus introduction, movements of infected pigs will originate at least once from 16 MS, with 6 MS spreading ASF in more than 10% of iterations. Two thirds of all intra-Community spread was linked to six trade links only. Denmark, the Netherlands, Lithuania and Latvia were identified

  10. A novel spatial and stochastic model to evaluate the within- and between-farm transmission of classical swine fever virus. I. General concepts and description of the model.

    PubMed

    Martínez-López, B; Ivorra, B; Ramos, A M; Sánchez-Vizcaíno, J M

    2011-01-27

    A new stochastic and spatial model was developed to evaluate the potential spread of classical swine fever virus (CSFV) within- and between-farms, and considering the specific farm-to-farm contact network. Within-farm transmission was simulated using a modified SI model. Between-farm transmission was assumed to occur by direct contacts (i.e. animal movement) and indirect contacts (i.e. local spread, vehicle and person contacts) and considering the spatial location of farms. Control measures dictated by the European legislation (i.e. depopulation of infected farms, movement restriction, zoning, surveillance, contact tracing) were also implemented into the model. Model experimentation was performed using real data from Segovia, one of the provinces with highest density of pigs in Spain, and results were presented using the mean, 95% probability intervals [95% PI] and risk maps. The estimated mean [95% PI] number of infected, quarantined and depopulated farms were 3 [1,17], 23 [0,76] and 115 [0,318], respectively. The duration of the epidemic was 63 [26,177] days and the most important way of transmission was associated with local spread (61.4% of the infections). Results were consistent with the spread of previous CSFV introductions into the study region. The model and results presented here may be useful for the decision making process and for the improvement of the prevention and control programmes for CSFV.

  11. Vulnerability of the British swine industry to classical swine fever

    PubMed Central

    Porphyre, Thibaud; Correia-Gomes, Carla; Chase-Topping, Margo E.; Gamado, Kokouvi; Auty, Harriet K.; Hutchinson, Ian; Reeves, Aaron; Gunn, George J.; Woolhouse, Mark E. J.

    2017-01-01

    Classical swine fever (CSF) is a notifiable, highly contagious viral disease of swine which results in severe welfare and economic consequences in affected countries. To improve preparedness, it is critical to have some understanding of how CSF would spread should it be introduced. Based on the data recorded during the 2000 epidemic of CSF in Great Britain (GB), a spatially explicit, premises-based model was developed to explore the risk of CSF spread in GB. We found that large outbreaks of CSF would be rare and generated from a limited number of areas in GB. Despite the consistently low vulnerability of the British swine industry to large CSF outbreaks, we identified concerns with respect to the role played by the non-commercial sector of the industry. The model further revealed how various epidemiological features may influence the spread of CSF in GB, highlighting the importance of between-farm biosecurity in preventing widespread dissemination of the virus. Knowledge of factors affecting the risk of spread are key components for surveillance planning and resource allocation, and this work provides a valuable stepping stone in guiding policy on CSF surveillance and control in GB. PMID:28225040

  12. A robust Bayesian approach to modeling epistemic uncertainty in common-cause failure models

    SciTech Connect

    Matthias C. M. Troffaes; Gero Walter; Dana Kelly

    2014-05-01

    In a standard Bayesian approach to the alpha-factor model for common-cause failure, a precise Dirichlet prior distribution models epistemic uncertainty in the alpha-factors. This Dirichlet prior is then updated with observed data to obtain a posterior distribution, which forms the basis for further inferences. In this paper, we adapt the imprecise Dirichlet model of Walley to represent epistemic uncertainty in the alpha-factors. In this approach, epistemic uncertainty is expressed more cautiously via lower and upper expectations for each alpha-factor, along with a learning parameter which determines how quickly the model learns from observed data. For this application, we focus on elicitation of the learning parameter, and find that values in the range of 1 to 10 seem reasonable. The approach is compared with Kelly and Atwood's minimally informative Dirichlet prior for the alpha-factor model, which incorporated precise mean values for the alpha-factors, but which was otherwise quite diffuse. Next, we explore the use of a set of Gamma priors to model epistemic uncertainty in the marginal failure rate, expressed via a lower and upper expectation for this rate, again along with a learning parameter. As zero counts are generally less of an issue here, we find that the choice of this learning parameter is less crucial. Finally, we demonstrate how both epistemic uncertainty models can be combined to arrive at lower and upper expectations for all common-cause failure rates. Thereby, we effectively provide a full sensitivity analysis of common-cause failure rates, properly reflecting epistemic uncertainty of the analyst on all levels of the common-cause failure model.

  13. Adequacy indices for dialysis in acute renal failure: kinetic modeling.

    PubMed

    Debowska, Malgorzata; Lindholm, Bengt; Waniewski, Jacek

    2010-05-01

    Many aspects of the management of renal replacement therapy in acute renal failure (ARF), including the appropriate assessment of dialysis adequacy, remain unresolved, because ARF patients often are not in a metabolic steady state. The aim of this study was to evaluate a system of adequacy indices for dialysis in ARF patients using urea and creatinine kinetic modeling. Kinetic modeling was performed for two different fictitious patients (A and B) with characteristics described by the average parameters for two patient groups and for two blood purification treatments: sustained low efficiency daily dialysis (SLEDD) in Patient A and continuous venovenous hemofiltration (CVVH) in Patient B, based on data from a clinical report. Urea and creatinine generation rates were estimated according to the clinical data on the solute concentrations in blood. Then, using estimated generation rates, two hypothetical treatments were simulated, CVVH in Patient A and SLEDD in Patient B. KT/V, fractional solute removal (FSR) and equivalent renal clearance (EKR) were calculated according to the definitions developed for metabolically unstable patients. CVVH appeared as being more effective than SLEDD because KT/V, FSR, and EKR were higher for CVVH than SLEDD in Patients A and B. Creatinine KT/V, FSR, and EKR were lower and well correlated to the respective indices for urea. Urea and creatinine generation rates were overestimated more than twice in Patient A and by 30-40% in Patient B if calculated assuming the metabolically stable state than if estimated by kinetic modeling. Adequacy indices and solute generation rates for ARF patients should be estimated using the definition for unsteady metabolic state. EKR and FSR were higher for urea and creatinine with CVVH than with SLEDD, because of higher K.T and minimized compartmental effects for CVVH.

  14. Pyruvate modifies metabolic flux and nutrient sensing during extracorporeal membrane oxygenation in an immature swine model

    SciTech Connect

    Ledee, Dolena R.; Kajimoto, Masaki; O'Kelly-Priddy, Colleen M.; Olson, Aaron; Isern, Nancy G.; Robillard Frayne, Isabelle; Des Rosiers, Christine; Portman, Michael A.

    2015-07-01

    Extracorporeal membrane oxygenation (ECMO) provides mechanical circulatory support for infants and children with postoperative cardiopulmonary failure. Nutritional support is mandatory during ECMO, although specific actions for substrates on the heart have not been delineated. Prior work shows that enhancing pyruvate oxidation promotes successful weaning from ECMO. Accordingly, we closely examined the role of prolonged systemic pyruvate supplementation in modifying metabolic parameters during the unique conditions of ventricular unloading provided by ECMO. Twelve male mixed breed Yorkshire piglets (age 30-49 days) received systemic infusion of either normal saline (Group C) or pyruvate (Group P) during ECMO for 8 hours. Over the final hour piglets received [2-13C] pyruvate, and [13C6]-L-leucine, as an indicator for oxidation and protein synthesis. A significant increase in lactate and pyruvate concentrations occurred, along with an increase in the absolute concentration of all measured CAC intermediates. Group P showed greater anaplerotic flux through pyruvate carboxylation although pyruvate oxidation relative to citrate synthase flux was similar to Group C. The groups demonstrated similar leucine fractional contributions to acetyl-CoA and fractional protein synthesis rates. Pyruvate also promoted an increase in the phosphorylation state of several nutrient sensitive enzymes, such as AMPK and ACC, and promoted O-GlcNAcylation through the hexosamine biosynthetic pathway (HBP). In conclusion, prolonged pyruvate supplementation during ECMO modified anaplerotic pyruvate flux and elicited changes in important nutrient and energy sensitive pathways, while preserving protein synthesis. Therefore, the observed results support the further study of nutritional supplementation and its downstream effects on cardiac adaptation during ventricular unloading.

  15. Intuitionistic fuzzy-based model for failure detection.

    PubMed

    Aikhuele, Daniel O; Turan, Faiz B M

    2016-01-01

    In identifying to-be-improved product component(s), the customer/user requirements which are mainly considered, and achieved through customer surveys using the quality function deployment (QFD) tool, often fail to guarantee or cover aspects of the product reliability. Even when they do, there are always many misunderstandings. To improve the product reliability and quality during product redesigning phase and to create that novel product(s) for the customers, the failure information of the existing product, and its component(s) should ordinarily be analyzed and converted to appropriate design knowledge for the design engineer. In this paper, a new intuitionistic fuzzy multi-criteria decision-making method has been proposed. The new approach which is based on an intuitionistic fuzzy TOPSIS model uses an exponential-related function for the computation of the separation measures from the intuitionistic fuzzy positive ideal solution (IFPIS) and intuitionistic fuzzy negative ideal solution (IFNIS) of alternatives. The proposed method has been applied to two practical case studies, and the result from the different cases has been compared with some similar computational approaches in the literature.

  16. Passive immunization with a polyclonal antiserum to the hemoglobin receptor of Haemophilus ducreyi confers protection against a homologous challenge in the experimental swine model of chancroid.

    PubMed

    Leduc, Isabelle; Fusco, William G; Choudhary, Neelima; Routh, Patty A; Cholon, Deborah M; Hobbs, Marcia M; Almond, Glen W; Orndorff, Paul E; Elkins, Christopher

    2011-08-01

    Haemophilus ducreyi, the etiologic agent of chancroid, has an obligate requirement for heme. Heme is acquired by H. ducreyi from its human host via TonB-dependent transporters expressed at its bacterial surface. Of 3 TonB-dependent transporters encoded in the genome of H. ducreyi, only the hemoglobin receptor, HgbA, is required to establish infection during the early stages of the experimental human model of chancroid. Active immunization with a native preparation of HgbA (nHgbA) confers complete protection in the experimental swine model of chancroid, using either Freund's or monophosphoryl lipid A as adjuvants. To determine if transfer of anti-nHgbA serum is sufficient to confer protection, a passive immunization experiment using pooled nHgbA antiserum was conducted in the experimental swine model of chancroid. Pigs receiving this pooled nHgbA antiserum were protected from a homologous, but not a heterologous, challenge. Passively transferred polyclonal antibodies elicited to nHgbA bound the surface of H. ducreyi and partially blocked hemoglobin binding by nHgbA, but were not bactericidal. Taken together, these data suggest that the humoral immune response to the HgbA vaccine is protective against an H. ducreyi infection, possibly by preventing acquisition of the essential nutrient heme.

  17. Ureteral Obstruction Swine Model through Laparoscopy and Single Port for Training on Laparoscopic Pyeloplasty

    PubMed Central

    Díaz-Güemes Martín-Portugués, Idoia; Hernández-Hurtado, Laura; Usón-Casaús, Jesús; Sánchez-Hurtado, Miguel Angel; Sánchez-Margallo, Francisco Miguel

    2013-01-01

    This study aims firstly to assess the most adequate surgical approach for the creation of an ureteropelvic juntion obstruction (UPJO) animal model, and secondly to validate this model for laparoscopic pyeloplasty training among urologists. Thirty six Large White pigs (28.29±5.48 Kg) were used. The left ureteropelvic junction was occluded by means of an endoclip. According to the surgical approach for model creation, pigs were randomized into: laparoscopic conventional surgery (LAP) or single port surgery (LSP). Each group was further divided into transperitoneal (+T) or retroperitoneal (+R) approach. Time needed for access, surgical field preparation, wound closure, and total surgical times were registered. Social behavior, tenderness to the touch and wound inflammation were evaluated in the early postoperative period. After ten days, all animals underwent an Anderson-Hynes pyeloplasty carried out by 9 urologists, who subsequently assessed the model by means of a subjective validation questionnaire. Total operative time was significantly greater in LSP+R (p=0.001). Tenderness to the touch was significantly increased in both retroperitoneal approaches, (p=0.0001). Surgeons rated the UPJO porcine model for training on laparoscopic pyeloplasty with high or very high scores, all above 4 on a 1-5 point Likert scale. Our UPJO animal model is useful for laparoscopic pyeloplasty training. The model created by retroperitoneal single port approach presented the best score in the subjective evaluation, whereas, as a whole, transabdominal laparoscopic approach was preferred. PMID:23801892

  18. Is Embolization of the Pancreas Safe? Pancreatic Histological Changes after Selective Transcatheter Arterial Embolization with N-Butyl Cyanoacrylate in a Swine Model

    SciTech Connect

    Okada, Takuya Yamaguchi, Masato; Takahashi, Takuya; Izaki, Kenta; Uotani, Kensuke; Sakamoto, Noriaki; Sugimura, Kazuro; Sugimoto, Koji

    2012-02-15

    Purpose: This study was designed to evaluate the safety of selective transcatheter arterial embolization (TAE) with N-butyl cyanoacrylate (NBCA) in a swine model in terms of histological changes in the pancreas. Methods: Three groups of two female swine (58-64 kg) per group underwent TAE of the dorsal pancreatic artery, under anesthesia, with 1:1, 1:4, and 1:9 mixtures of NBCA and iodized oil. Blood parameters were evaluated at days 1, 4, and 10 after TAE, after which the animals were sacrificed and pancreatic tissues were examined under light microscopy. Results: All of the animals were asymptomatic and survived for 10 days. Cone beam computed tomographic angiography revealed occlusion of the dorsal pancreatic artery and no enhancement in the embolized area. The white blood cell count and C-reactive protein level were elevated slightly on day 1 after TAE (mean {+-} SD: 252.7 {+-} 27.8 Multiplication-Sign 10{sup 2}/{mu}l and 0.15 {+-} 0.07 mg/l, respectively), but they normalized or remained near the upper normal limit thereafter. The serum amylase and lipase levels also were elevated on day 1 (8831.7 {+-} 2169.2 U/l and 130 {+-} 53.4 U/l, respectively) but normalized thereafter. Histologically, necrosis and fibrosis were noted only in the embolized segment, and necrosis and acute inflammatory reactions were absent in the nonembolized segment. The border between both segments was well defined. Lymphocytic infiltration and foreign body reaction were noted around the embolized vessels. Conclusions: Selective TAE with NBCA in the pancreas caused localized ischemic necrosis without clinically significant pancreatitis; therefore, this procedure is tolerable in swine.

  19. An evaluation of two conducted electrical weapons using a swine comparative cardiac safety model.

    PubMed

    Dawes, Donald M; Ho, Jeffrey D; Moore, Johanna C; Laudenbach, Andrew P; Reardon, Robert F; Miner, James R

    2014-09-01

    Arrest-related deaths proximate to the use of a conducted electrical weapon (CEW) continue to generate controversy despite a better understanding of the multi-factorial nature of many of these deaths. With the rapid adoption of this technology by law enforcement, and the proliferation of companies entering the marketplace, it is important to have a method to assess the relative safety of these weapons. We had previously developed a model to assess the relative cardiac safety of CEWs. In this study, we use this model to compare the TASER X2 and the Karbon Arms MPID. Our results suggest that the TASER X2 may have an improved cardiac safety margin over the Karbon Arms MPID as determined by a smaller area of cardiac pacing on the anterior chest in our model. This model seems to offer a reproducible means of comparing the cardiac effects of CEWs.

  20. Real Time Fire Reconnaissance Satellite Monitoring System Failure Model

    NASA Astrophysics Data System (ADS)

    Nino Prieto, Omar Ariosto; Colmenares Guillen, Luis Enrique

    2013-09-01

    In this paper the Real Time Fire Reconnaissance Satellite Monitoring System is presented. This architecture is a legacy of the Detection System for Real-Time Physical Variables which is undergoing a patent process in Mexico. The methodologies for this design are the Structured Analysis for Real Time (SA- RT) [8], and the software is carried out by LACATRE (Langage d'aide à la Conception d'Application multitâche Temps Réel) [9,10] Real Time formal language. The system failures model is analyzed and the proposal is based on the formal language for the design of critical systems and Risk Assessment; AltaRica. This formal architecture uses satellites as input sensors and it was adapted from the original model which is a design pattern for physical variation detection in Real Time. The original design, whose task is to monitor events such as natural disasters and health related applications, or actual sickness monitoring and prevention, as the Real Time Diabetes Monitoring System, among others. Some related work has been presented on the Mexican Space Agency (AEM) Creation and Consultation Forums (2010-2011), and throughout the International Mexican Aerospace Science and Technology Society (SOMECYTA) international congress held in San Luis Potosí, México (2012). This Architecture will allow a Real Time Fire Satellite Monitoring, which will reduce the damage and danger caused by fires which consumes the forests and tropical forests of Mexico. This new proposal, permits having a new system that impacts on disaster prevention, by combining national and international technologies and cooperation for the benefit of humankind.

  1. Electromyographic study of differential sensitivity to succinylcholine of the diaphragm, laryngeal and somatic muscles: a swine model.

    PubMed

    Lu, I-Cheng; Wang, Hsun-Mo; Kuo, Yi-Wei; Shieh, Chia-Fang; Chiang, Feng-Yu; Wu, Che-Wei; Tsai, Cheng-Jing

    2010-12-01

    Neuromuscular blocking agents (NMBAs) might diminish the electromyography signal of the vocalis muscles during intraoperative neuromonitoring of the recurrent laryngeal nerve. The aim of this study was to compare differential sensitivity of different muscles to succinylcholine in a swine model, and to realize the influence of NMBAs on neuromonitoring. Six male Duroc-Landrace piglets were anesthetized with thiamylal and underwent tracheal intubation without the use of an NMBA. The left recurrent laryngeal nerve, the spinal accessory nerve, the right phrenic nerve and the brachial plexus were stimulated. Evoked potentials (electromyography signal) of four muscle groups were elicited from needle electrodes before and after intravenous succinylcholine bolus (1.0 mg/kg). Recorded muscles included the vocalis muscles, trapezius muscle, diaphragm and triceps brachii muscles. The onset time and 80% recovery of control response were recorded and analyzed. The testing was repeated after 30 minutes. The onset time of neuromuscular blocking for the vocalis muscles, trapezius muscle, diaphragm and triceps brachii muscle was 36.3 ± 6.3 seconds, 38.8 ± 14.9 seconds, 52.5 ± 9.7 seconds and 45.0 ± 8.2 seconds during the first test; and 49.3 ± 10.8 seconds, 40.0 ± 12.2 seconds, 47.5 ± 11.9 seconds and 41.3 ± 10.1 seconds during the second test. The 80% recovery of the control response for each muscle was 18.3 ± 2.7 minutes, 16.5±6.9 minutes, 8.1±2.5 minutes and 14.8±2.9 minutes during the first test; and 21.5±3.8 minutes, 12.5 ± 4.3 minutes, 10.5 ± 3.1 minutes and 16.4 ± 4.2 minutes during the second test. The sensitivity of the muscles to succinylcholine, ranked in order, was: the vocalis muscles, the triceps brachii muscle, the trapezius muscle and the diaphragm. We demonstrated a useful and reliable animal model to investigate the effects of NMBAs on intraoperative neuromonitoring. Extrapolation of these data to humans should be done with caution.

  2. Improved Patency of Transjugular Intrahepatic Portosystemic Shunt: The Efficacy of Cilostazol for the Prevention of Pseudointimal Hyperplasia in Swine TIPS Models

    SciTech Connect

    Park, Sang Woo Cha, In Ho; Kim, Chul Hwan; Jeon, Hae Jeong; Park, Jeong Hee; Hong, Suk Joo; Lee, In Sik

    2007-07-15

    Purpose. To investigate the efficacy of oral administration of cilostazol to inhibit pseudointimal/intimal hyperplasia in swine TIPS models. Methods. Successful TIPS creation was carried out in 11 of 12 healthy young pigs (20-25 kg). In the treatment group (n = 6), both cilostazol and aspirin were administered daily, from the first day of TIPS creation. The control group (n = 5) was administered only aspirin. The animals were followed-up for 2 weeks and then killed. The specimen (including portal vein, hepatic parenchymal tract, hepatic vein, and inferior vena cava) and stents were carefully bisected in a longitudinal fashion. The control group was compared with the treatment group by means of a gross and histologic evaluation of the degree of pseudointimal/intimal hyperplasia in the shunt. Results. At the gross evaluation, the control group showed considerably more pseudointimal/intimal hyperplasia than the treatment group. Using microscopic evaluation, there was a statistically significant difference (p < 0.05) in the mean maximum pseudointimal/intimal hyperplasia thickness between the control group (2.97 {+-} 0.33 mm) and treatment group (0.73 {+-} 0.27 mm). Conclusion. Oral administration of cilostazol may have been effective in reducing pseudointimal/intimal hyperplasia in swine TIPS models.

  3. 9 CFR 85.10 - Interstate movement of swine semen and swine embryos for insemination of or implantation into swine.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... swine embryos for insemination of or implantation into swine. 85.10 Section 85.10 Animals and Animal... and swine embryos for insemination of or implantation into swine. Swine semen and swine embryos moved... collection of the semen or embryos or were members of a qualified pseudorabies negative herd, and had...

  4. 9 CFR 85.10 - Interstate movement of swine semen and swine embryos for insemination of or implantation into swine.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... swine embryos for insemination of or implantation into swine. 85.10 Section 85.10 Animals and Animal... and swine embryos for insemination of or implantation into swine. Swine semen and swine embryos moved... collection of the semen or embryos or were members of a qualified pseudorabies negative herd, and had...

  5. 9 CFR 85.10 - Interstate movement of swine semen and swine embryos for insemination of or implantation into swine.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... swine embryos for insemination of or implantation into swine. 85.10 Section 85.10 Animals and Animal... and swine embryos for insemination of or implantation into swine. Swine semen and swine embryos moved... collection of the semen or embryos or were members of a qualified pseudorabies negative herd, and had...

  6. 9 CFR 85.10 - Interstate movement of swine semen and swine embryos for insemination of or implantation into swine.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... swine embryos for insemination of or implantation into swine. 85.10 Section 85.10 Animals and Animal... and swine embryos for insemination of or implantation into swine. Swine semen and swine embryos moved... collection of the semen or embryos or were members of a qualified pseudorabies negative herd, and had...

  7. 9 CFR 85.10 - Interstate movement of swine semen and swine embryos for insemination of or implantation into swine.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... swine embryos for insemination of or implantation into swine. 85.10 Section 85.10 Animals and Animal... and swine embryos for insemination of or implantation into swine. Swine semen and swine embryos moved... collection of the semen or embryos or were members of a qualified pseudorabies negative herd, and had...

  8. Process model for ammonia volatilization from anaerobic swine lagoons incorporating varying wind speeds and biogas bubbling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ammonia volatilization from treatment lagoons varies widely with the total ammonia concentration, pH, temperature, suspended solids, atmospheric ammonia concentration above the water surface, and wind speed. Ammonia emissions were estimated with a process-based mechanistic model integrating ammonia ...

  9. A Leasing Model to Deal with Partial Failures in Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Gonzalez Boix, Elisa; van Cutsem, Tom; Vallejos, Jorge; de Meuter, Wolfgang; D'Hondt, Theo

    In mobile ad hoc networks (MANETs) many partial failures are the result of temporary network partitions due to the intermittent connectivity of mobile devices. Some of these failures will be permanent and require application-level failure handling. However, it is impossible to distinguish a permanent from a transient failure. Leasing provides a solution to this problem based on the temporal restriction of resources. But to date no leasing model has been designed specifically for MANETs. In this paper, we identify three characteristics required for a leasing model to be usable in a MANET, discuss the issues with existing leasing models and then propose the leased object references model, which integrates leasing with remote object references. In addition, we describe an implementation of the model in the programming language AmbientTalk. Leased object references provide an extensible framework that allows programmers to express their own leasing patterns and enables both lease holders (clients) and lease grantors (services) to deal with permanent failures.

  10. Anisotropic Tensile Failure Model of Rapid Prototyping Parts - Fused Deposition Modeling (FDM)

    NASA Astrophysics Data System (ADS)

    Ahn, Sung Hoon; Baek, Changil; Lee, Sunyoung; Ahn, In Shup

    Stratasys' Fused Deposition Modeling (FDM) is a typical Rapid Prototyping (RP) process that can fabricate prototypes out of plastic materials, and the parts made from FDM were often used as load-carrying elements. Because FDM deposits materials in about 300 μm thin filament with designated orientation, parts made from FDM show anisotropic material behaviors. This paper proposes an analytic model to predict the tensile strength of FDM parts. Applying the Classical Lamination Theory and Tsai-Wu failure criterion, which were developed for laminated composite materials, a computer code was implemented to predict the failure of the FDM parts. The tensile strengths predicted by the analytic model were compared with those of the experimental data. The data and predicted values agreed reasonably well to prove the validity of the model.

  11. Myocardial Drug Distribution Generated from Local Epicardial Application: Potential Impact of Cardiac Capillary Perfusion in a Swine Model Using Epinephrine

    PubMed Central

    Maslov, Mikhail Y.; Edelman, Elazer R.; Pezone, Matthew J.; Wei, Abraham E.; Wakim, Matthew G.; Murray, Michael R.; Tsukada, Hisashi; Gerogiannis, Iraklis S.; Groothuis, Adam; Lovich, Mark A.

    2014-01-01

    Prior studies in small mammals have shown that local epicardial application of inotropic compounds drives myocardial contractility without systemic side effects. Myocardial capillary blood flow, however, may be more significant in larger species than in small animals. We hypothesized that bulk perfusion in capillary beds of the large mammalian heart enhances drug distribution after local release, but also clears more drug from the tissue target than in small animals. Epicardial (EC) drug releasing systems were used to apply epinephrine to the anterior surface of the left heart of swine in either point-sourced or distributed configurations. Following local application or intravenous (IV) infusion at the same dose rates, hemodynamic responses, epinephrine levels in the coronary sinus and systemic circulation, and drug deposition across the ventricular wall, around the circumference and down the axis, were measured. EC delivery via point-source release generated transmural epinephrine gradients directly beneath the site of application extending into the middle third of the myocardial thickness. Gradients in drug deposition were also observed down the length of the heart and around the circumference toward the lateral wall, but not the interventricular septum. These gradients extended further than might be predicted from simple diffusion. The circumferential distribution following local epinephrine delivery from a distributed source to the entire anterior wall drove drug toward the inferior wall, further than with point-source release, but again, not to the septum. This augmented drug distribution away from the release source, down the axis of the left ventricle, and selectively towards the left heart follows the direction of capillary perfusion away from the anterior descending and circumflex arteries, suggesting a role for the coronary circulation in determining local drug deposition and clearance. The dominant role of the coronary vasculature is further suggested by

  12. Effects of ageing and soil properties on the oral bioavailability of benzo[a]pyrene using a swine model.

    PubMed

    Duan, Luchun; Palanisami, Thavamani; Liu, Yanju; Dong, Zhaomin; Mallavarapu, Megharaj; Kuchel, Tim; Semple, Kirk T; Naidu, Ravi

    2014-09-01

    Oral bioavailability of benzo[a]pyrene (B[a]P) was studied in a swine model using eight spiked soil samples after incubation for 50 and/or 90 days. Silica sand was used as a reference material and the relative bioavailability (RB) of B[a]P in soils was calculated as the quotient of the area under the plasma B[a]P curve (AUC) for soil and AUC for the silica sand. Significantly reduced RB was observed in all study soils after 90 days ageing, ranging from 22.1±0.4% to 62.7±10.1%, except for one very sandy soil (sand content 87.6%) where RB was unchanged (108.1±8.0%). Apart from this, bioavailability decreased during ageing with the decrease (from day 50 to day 90) being only significant for a clayey soil containing expandable clay minerals. Statistical analyses of B[a]P RB at day 90 (eight soils) and soil properties showed no direct correlation between RB and specific soil properties such as total organic carbon (TOC) and clay content which were commonly linked to organic contaminant sequestration. However, strongly significant relationships (p<0.001) were found between RB and the fine particle associated carbon (FPAC) defined as (Silt+Clay)/TOC, and between RB and the soil mesopore (<6nm; p<0.001) fraction, after two samples with high pH and high EC being excluded from the analyses. The bioaccessibility estimated by four in vitro extraction methods: dichloromethane/acetone sonication (DCM/Ace), butanol vortex (BuOH), hydroxypropyl-β-cyclodextrin extraction (HPCD) and Milli Q water leaching methods at different sampling time (1 day, 50 days and 90 days after spiking) also showed a decreasing trend. Significant correlations were found between B[a]P RB and DCM/Ace (R(2)=0.67, p<0.05) extractable fraction and BuOH (R(2)=0.75, p<0.01) extractable fraction.

  13. Bayesian accelerated failure time model for space-time dependency in a geographically augmented survival model

    PubMed Central

    Onicescu, Georgiana; Lawson, Andrew; Zhang, Jiajia; Gebregziabher, Mulugeta; Wallace, Kristin; Eberth, Jan M

    2016-01-01

    In this paper, we extend the spatially explicit survival model for small area cancer data by allowing dependency between space and time and using accelerated failure time models. Spatial dependency is modeled directly in the definition of the survival, density, and hazard functions. The models are developed in the context of county level aggregated data. Two cases are considered: the first assumes that the spatial and temporal distributions are independent; the second allows for dependency between the spatial and temporal components. We apply the models to prostate cancer data from the Louisiana SEER cancer registry. PMID:26220537

  14. Comparison of 10 Hemostatic Dressings in a Groin Puncture Model in Swine

    DTIC Science & Technology

    2009-09-01

    compression (about 175 mm Hg), and at 15 minutes, 500 mL resuscitation fluid (Hextand) was infused during a 30-minute period. The animals were monitored...fascia tissue. Lidocaine (Henry Schein, Inc) (1% to 2%) was spread on the artery to maximize dilation of the vessel. Any proximal side branches from the...the dressing and natural physiologic compensation after one 500-mL bolus infusion at 15 minutes without additional fluid. In our model, MAP decreased

  15. Evaluation of the gamma-H2AX assay for radiation biodosimetry in a swine model.

    PubMed

    Moroni, Maria; Maeda, Daisuke; Whitnall, Mark H; Bonner, William M; Redon, Christophe E

    2013-07-08

    There is a paucity of large animal models to study both the extent and the health risk of ionizing radiation exposure in humans. One promising candidate for such a model is the minipig. Here, we evaluate the minipig for its potential in γ-H2AX-based biodosimetry after exposure to ionizing radiation using both Cs137 and Co60 sources. γ-H2AX foci were enumerated in blood lymphocytes and normal fibroblasts of human and porcine origin after ex vivo γ-ray irradiation. DNA double-strand break repair kinetics in minipig blood lymphocytes and fibroblasts, based on the γ-H2AX assay, were similar to those observed in their human counterparts. To substantiate the similarity observed between the human and minipig we show that minipig fibroblast radiosensitivity was similar to that observed with human fibroblasts. Finally, a strong γ-H2AX induction was observed in blood lymphocytes following minipig total body irradiation. Significant responses were detected 3 days after 1.8 Gy and 1 week after 3.8 and 5 Gy with residual γ-H2AX foci proportional to the initial radiation doses. These findings show that the Gottingen minipig provides a useful in vivo model for validation of γ-H2AX biodosimetry for dose assessment in humans.

  16. Evaluation of the Gamma-H2AX Assay for Radiation Biodosimetry in a Swine Model

    PubMed Central

    Moroni, Maria; Maeda, Daisuke; Whitnall, Mark H.; Bonner, William M.; Redon, Christophe E.

    2013-01-01

    There is a paucity of large animal models to study both the extent and the health risk of ionizing radiation exposure in humans. One promising candidate for such a model is the minipig. Here, we evaluate the minipig for its potential in γ-H2AX-based biodosimetry after exposure to ionizing radiation using both Cs137 and Co60 sources. γ-H2AX foci were enumerated in blood lymphocytes and normal fibroblasts of human and porcine origin after ex vivo γ-ray irradiation. DNA double-strand break repair kinetics in minipig blood lymphocytes and fibroblasts, based on the γ-H2AX assay, were similar to those observed in their human counterparts. To substantiate the similarity observed between the human and minipig we show that minipig fibroblast radiosensitivity was similar to that observed with human fibroblasts. Finally, a strong γ-H2AX induction was observed in blood lymphocytes following minipig total body irradiation. Significant responses were detected 3 days after 1.8 Gy and 1 week after 3.8 and 5 Gy with residual γ-H2AX foci proportional to the initial radiation doses. These findings show that the Gottingen minipig provides a useful in vivo model for validation of γ-H2AX biodosimetry for dose assessment in humans. PMID:23880859

  17. Numerical simulation of failure behavior of granular debris flows based on flume model tests.

    PubMed

    Zhou, Jian; Li, Ye-xun; Jia, Min-cai; Li, Cui-na

    2013-01-01

    In this study, the failure behaviors of debris flows were studied by flume model tests with artificial rainfall and numerical simulations (PFC(3D)). Model tests revealed that grain sizes distribution had profound effects on failure mode, and the failure in slope of medium sand started with cracks at crest and took the form of retrogressive toe sliding failure. With the increase of fine particles in soil, the failure mode of the slopes changed to fluidized flow. The discrete element method PFC(3D) can overcome the hypothesis of the traditional continuous medium mechanic and consider the simple characteristics of particle. Thus, a numerical simulations model considering liquid-solid coupled method has been developed to simulate the debris flow. Comparing the experimental results, the numerical simulation result indicated that the failure mode of the failure of medium sand slope was retrogressive toe sliding, and the failure of fine sand slope was fluidized sliding. The simulation result is consistent with the model test and theoretical analysis, and grain sizes distribution caused different failure behavior of granular debris flows. This research should be a guide to explore the theory of debris flow and to improve the prevention and reduction of debris flow.

  18. Multiscale Model Predicts Tissue-Level Failure From Collagen Fiber-Level Damage

    PubMed Central

    Hadi, Mohammad F.; Sander, Edward A.; Barocas, Victor H.

    2013-01-01

    Excessive tissue-level forces communicated to the microstructure and extracellular matrix of soft tissues can lead to damage and failure through poorly understood physical processes that are multiscale in nature. In this work, we propose a multiscale mechanical model for the failure of collagenous soft tissues that incorporates spatial heterogeneity in the microstructure and links the failure of discrete collagen fibers to the material response of the tissue. The model, which is based on experimental failure data derived from different collagen gel geometries, was able to predict the mechanical response and failure of type I collagen gels, and it demonstrated that a fiber-based rule (at the micrometer scale) for discrete failure can strongly shape the macroscale failure response of the gel (at the millimeter scale). The model may be a useful tool in predicting the macroscale failure conditions for soft tissues and engineered tissue analogs. In addition, the multiscale model provides a framework for the study of failure in complex fiber-based mechanical systems in general. PMID:22938372

  19. Numerical Simulation of Failure Behavior of Granular Debris Flows Based on Flume Model Tests

    PubMed Central

    Zhou, Jian; Li, Ye-xun; Jia, Min-cai; Li, Cui-na

    2013-01-01

    In this study, the failure behaviors of debris flows were studied by flume model tests with artificial rainfall and numerical simulations (PFC3D). Model tests revealed that grain sizes distribution had profound effects on failure mode, and the failure in slope of medium sand started with cracks at crest and took the form of retrogressive toe sliding failure. With the increase of fine particles in soil, the failure mode of the slopes changed to fluidized flow. The discrete element method PFC3D can overcome the hypothesis of the traditional continuous medium mechanic and consider the simple characteristics of particle. Thus, a numerical simulations model considering liquid-solid coupled method has been developed to simulate the debris flow. Comparing the experimental results, the numerical simulation result indicated that the failure mode of the failure of medium sand slope was retrogressive toe sliding, and the failure of fine sand slope was fluidized sliding. The simulation result is consistent with the model test and theoretical analysis, and grain sizes distribution caused different failure behavior of granular debris flows. This research should be a guide to explore the theory of debris flow and to improve the prevention and reduction of debris flow. PMID:23766700

  20. Failure of sewage pumps: statistical modelling and impact assessment.

    PubMed

    Korving, H; Geise, M; Clemens, F

    2006-01-01

    Sewage pumping stations are directly responsible for affecting performance, i.e. failing pumps may result in combined sewer overflows or flooding. However, failures of sewage pumps are not yet incorporated in sewer assessments due to lack of knowledge and data. This paper presents the analysis of pump failure data provided by two sewer management authorities in The Netherlands. Pump failures have been studied accounting for the nature of the failures, the operation and maintenance procedures of the management authority, the ageing of the pumps and the changes in the environment of pumps. The analysis shows that sewage pumps fail relatively often due to the composition of sewage and the discontinuous operation of the pumps. The interarrival time and the duration of failures are highly variable and independent of the pump type and the specific function of the pump. The results also indicate that the serviceability of sewer systems is significantly affected by failing pumps. As a consequence, part of the environmental damage due to CSOs (combined sewer overflows) can be avoided by improving maintenance of pumping stations.

  1. High-resolution magic angle spinning (1)H magnetic resonance spectroscopy detects choline as a biomarker in a swine obstructive chronic pancreatitis model at an early stage.

    PubMed

    Sun, Gaofeng; Wang, Jianhua; Zhang, Jian; Ma, Chao; Shao, Chengwei; Hao, Jun; Zheng, Jianming; Feng, Xiaoyuan; Zuo, Changjing

    2014-03-04

    Chronic pancreatitis (CP) is a progressive inflammatory and fibrotic disease of the pancreas which encompasses a variety of clinical syndromes ranging from mild to life-threatening complications. Metabolomics has increasingly been applied to identify biomarkers for disease diagnosis with particular interest in diseases at an early stage. In this study, we tested a swine obstructive CP model by subtotal ligation of the main pancreatic duct, and the metabolic profiles of the Bama miniature swine pancreas were investigated using high-resolution magic angle spinning proton magnetic resonance spectroscopy (HR MAS (1)H MRS) combined with principal components analysis (PCA). Increases in lactate and choline for mild CP and decreases in glycerophosphocholine, phosphocholine, betaine and glycine were observed from normal pancreas to mild, moderate and severe CP. PCA results showed visual separations among the groups. The increase of choline at an early stage of CP and the decrease of glycerophosphocholine, phosphocholine, betaine and glycine reveal the pathogenesis of CP at a molecular level. The MRS results presented here demonstrate the potential of metabolic profiles in discriminating a normal pancreas from different stages of CP, which may be used to achieve CP early diagnosis and timely intervention to prevent irreversible destruction of the pancreas.

  2. Finite element modelling of woven composite failure modes at the mesoscopic scale: deterministic versus stochastic approaches

    NASA Astrophysics Data System (ADS)

    Roirand, Q.; Missoum-Benziane, D.; Thionnet, A.; Laiarinandrasana, L.

    2017-01-01

    Textile composites are composed of 3D complex architecture. To assess the durability of such engineering structures, the failure mechanisms must be highlighted. Examinations of the degradation have been carried out thanks to tomography. The present work addresses a numerical damage model dedicated to the simulation of the crack initiation and propagation at the scale of the warp yarns. For the 3D woven composites under study, loadings in tension and combined tension and bending were considered. Based on an erosion procedure of broken elements, the failure mechanisms have been modelled on 3D periodic cells by finite element calculations. The breakage of one element was determined using a failure criterion at the mesoscopic scale based on the yarn stress at failure. The results were found to be in good agreement with the experimental data for the two kinds of macroscopic loadings. The deterministic approach assumed a homogeneously distributed stress at failure all over the integration points in the meshes of woven composites. A stochastic approach was applied to a simple representative elementary periodic cell. The distribution of the Weibull stress at failure was assigned to the integration points using a Monte Carlo simulation. It was shown that this stochastic approach allowed more realistic failure simulations avoiding the idealised symmetry due to the deterministic modelling. In particular, the stochastic simulations performed have shown several variations of the stress as well as strain at failure and the failure modes of the yarn.

  3. Swine Fecal Metagenomics

    EPA Science Inventory

    Metagenomic approaches are providing rapid and more robust means to investigate the composition and functional genetic potential of complex microbial communities. In this study, we utilized a metagenomic approach to further understand the functional diversity of the swine gut. To...

  4. Implementation of a PETN failure model using ARIA's general chemistry framework

    SciTech Connect

    Hobbs, Michael L.

    2017-01-01

    We previously developed a PETN thermal decomposition model that accurately predicts thermal ignition and detonator failure [1]. This model was originally developed for CALORE [2] and required several complex user subroutines. Recently, a simplified version of the PETN decomposition model was implemented into ARIA [3] using a general chemistry framework without need for user subroutines. Detonator failure was also predicted with this new model using ENCORE. The model was simplified by 1) basing the model on moles rather than mass, 2) simplifying the thermal conductivity model, and 3) implementing ARIA’s new phase change model. This memo briefly describes the model, implementation, and validation.

  5. Extremely low frequency electromagnetic field exposure affects fertilization outcome in swine animal model.

    PubMed

    Bernabò, N; Tettamanti, E; Russo, V; Martelli, A; Turriani, M; Mattoli, M; Barboni, B

    2010-06-01

    Modern society continuously exposes the population to electromagnetic radiation, the effects of which on human health, in particular reproduction, are still unknown. The aim of this research was to assess the effect of acute (1h) exposure of boar spermatozoa to a 50 Hz extremely low frequency electromagnetic field (ELF-EMF) on early fertility outcome. The effect of intensities ranging from 0 to 2 mT on morpho-functional integrity of capacitated spermatozoa was examined in vitro. The oviducts containing or without spermatozoa were then exposed to the minimum in vivo, TD(50,) and maximum intensities determined in vitro, 4h before ovulation. The effects of ELF-EMF on spermatozoa in terms of early embryo development were evaluated after 12h and 6 days. It was found that in vitro ELF-EMF > 0.5 mT induced a progressive acrosome damage, thus compromising the ability of spermatozoa to undergo acrosomal reaction after zona pellucida stimulation and reducing the in vitro fertilization outcome. These effects became evident at 0.75 mT and reached the plateau at 1 mT. Under in vivo conditions, the ELF-EMF intensity of 1 mT was able to compromise sperm function, significantly reducing the fertilization rate. In addition, the exposure of oviducts to fields > or = 0.75 mT in the absence of spermatozoa was able to negatively affect early embryo development. In fact, it was found to cause a slowdown in the embryo cleavage. In conclusion, it was demonstrated how and at which intensities ELF-EMF negatively affect early fertility outcome in a highly predictive animal model.

  6. Pharmacokinetics and efficacy of 5-aminolaevulinic acid for endovascular photodynamic therapy in a swine model

    NASA Astrophysics Data System (ADS)

    Jenkins, Michael P.; Buonaccorsi, Giovanni A.; MacRobert, Alexander J.; Bishop, Christopher C. R.; Bown, Stephen G.; McEwan, Jean R.

    1998-07-01

    Vascular smooth muscle cells (VSMC) are known to be important in restenosis and photodynamic therapy (PDT) has been shown experimentally to deplete the VSMC population in small animal studies. We aimed to investigate the pharmacokinetics of 5- aminolaevulinic acid (5-ALA) and to see if endovascular PDT was feasible in a large animal model. Large White pigs (15 - 20 Kg) were photosensitized with 5-ALA at a concentration of 60 and 120 mg/Kg. Arterial biopsies were taken at intervals between 30 mins and 24 hours and snap frozen in liquid nitrogen. Frozen sections were analyzed using a CCD camera and PpIX activity assessed by computing pixel counts for intima, media and adventitia at each time point. Based on the above results 8 pigs were treated with PDT at 1.5, 2.5 or 6 hours following 5-ALA administration. Iliac segments were then illuminated with 50 J/cm2, 635 nm wavelength light via a 4 mm transparent PTA balloon. Animals were culled at 3 days and the above segments pressure perfused in situ with 4% formyl saline, before being excised and fixed. Fluorescence peaked in the adventitia at 1.5 hours, was minimal at 2.5 hours and peaked in the media at 6 hours post 5-ALA. Of the second series of 8 pigs, all animals survived to culling and all treated arteries remained patent. Histological sections stained with H&E were examined and medial VSMC's counted in 4 individual high power fields per section. The mean VSMC count per HPF for PDT treated segments was 16, 51 and 12 at 1.5, 2.5 and 6 hours respectively. VSMC counts in ALA alone controls and light alone controls were 115 and 103 respectively (p less than 0.0001). Endovascular delivery of light to 5-ALA sensitized animals is therefore feasible and was not associated with any complications.

  7. Pharmacokinetic and Pharmacodynamic Integration and Modeling of Enrofloxacin in Swine for Escherichia coli.

    PubMed

    Wang, Jianyi; Hao, Haihong; Huang, Lingli; Liu, Zhenli; Chen, Dongmei; Yuan, Zonghui

    2016-01-01

    The aim of this study was to optimize the dose regimens of enrofloxacin to reduce the development of fluoroquinolone resistance in Escherichia coli (E.coli) using pharmacokinetic/pharmacodynamic (PK/PD) modeling approach. The single dose (2.5 mg/kg body weight) of enrofloxacin was administered intramuscularly (IM) to the healthy pigs. Using cannulation, the pharmacokinetic properties, including peak concentration (C max), time to reach C max (T max), and area under the curve (AUC), were determined in plasma and ileum content. The C max, T max, and AUC in the plasma were 1.09 ± 0.11 μg/mL, 1.27 ± 0.35 h, and 12.70 ± 2.72 μg·h/mL, respectively. While in ileum content, the C max, T max, and AUC were 7.07 ± 0.26 μg/mL, 5.54 ± 0.42 h, and 136.18 ± 12.50 μg·h/mL, respectively. Based on the minimum inhibitory concentration (MIC) data of 918 E. coli isolates, an E. coli O101/K99 strain (enrofloxacin MIC = 0.25 μg/mL) was selected for pharmacodynamic studies. The in vitro minimum bactericidal concentration (MBC), mutant prevention concentration (MPC), and ex vivo time-killing curves for enrofloxacin in ileum content were established against the selected E. coli O101/K99 strain. Integrating the in vivo pharmacokinetic data and ex vivo pharmacodynamic data, a sigmoid E max (Hill) equation was established to provide values for ileum content of AUC24h/MIC producing, bactericidal activity (52.65 h), and virtual eradication of bacteria (78.06 h). A dosage regimen of 1.96 mg/kg every 12 h for 3 days should be sufficient in the treatment of E. coli.

  8. Common Cause Failure Modeling in Space Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Hark, Frank; Ring, Rob; Novack, Steven D.; Britton, Paul

    2015-01-01

    Common Cause Failures (CCFs) are a known and documented phenomenon that defeats system redundancy. CCFs are a set of dependent type of failures that can be caused for example by system environments, manufacturing, transportation, storage, maintenance, and assembly. Since there are many factors that contribute to CCFs, they can be reduced, but are difficult to eliminate entirely. Furthermore, failure databases sometimes fail to differentiate between independent and dependent CCF. Because common cause failure data is limited in the aerospace industry, the Probabilistic Risk Assessment (PRA) Team at Bastion Technology Inc. is estimating CCF risk using generic data collected by the Nuclear Regulatory Commission (NRC). Consequently, common cause risk estimates based on this database, when applied to other industry applications, are highly uncertain. Therefore, it is important to account for a range of values for independent and CCF risk and to communicate the uncertainty to decision makers. There is an existing methodology for reducing CCF risk during design, which includes a checklist of 40+ factors grouped into eight categories. Using this checklist, an approach to produce a beta factor estimate is being investigated that quantitatively relates these factors. In this example, the checklist will be tailored to space launch vehicles, a quantitative approach will be described, and an example of the method will be presented.

  9. Model-Biased, Data-Driven Adaptive Failure Prediction

    NASA Technical Reports Server (NTRS)

    Leen, Todd K.

    2004-01-01

    This final report, which contains a research summary and a viewgraph presentation, addresses clustering and data simulation techniques for failure prediction. The researchers applied their techniques to both helicopter gearbox anomaly detection and segmentation of Earth Observing System (EOS) satellite imagery.

  10. Predicting Time Series Outputs and Time-to-Failure for an Aircraft Controller Using Bayesian Modeling

    NASA Technical Reports Server (NTRS)

    He, Yuning

    2015-01-01

    Safety of unmanned aerial systems (UAS) is paramount, but the large number of dynamically changing controller parameters makes it hard to determine if the system is currently stable, and the time before loss of control if not. We propose a hierarchical statistical model using Treed Gaussian Processes to predict (i) whether a flight will be stable (success) or become unstable (failure), (ii) the time-to-failure if unstable, and (iii) time series outputs for flight variables. We first classify the current flight input into success or failure types, and then use separate models for each class to predict the time-to-failure and time series outputs. As different inputs may cause failures at different times, we have to model variable length output curves. We use a basis representation for curves and learn the mappings from input to basis coefficients. We demonstrate the effectiveness of our prediction methods on a NASA neuro-adaptive flight control system.

  11. Extension of pipe failure models to consider the absence of data from replaced pipes.

    PubMed

    Scheidegger, Andreas; Scholten, Lisa; Maurer, Max; Reichert, Peter

    2013-07-01

    Predictions of the expected number of failures of water distribution network pipes are important to develop an optimal management strategy. A number of probabilistic pipe failure models have been proposed in the literature for this purpose. They have to be calibrated on failure records. However, common data management practices mean that replaced pipes are often absent from available data sets. This leads to a 'survival selection bias', as pipes with frequent failures are more likely to be absent from the data. To address this problem, we propose a formal statistical approach to extend the likelihood function of a pipe failure model by a replacement model. Frequentist maximum likelihood estimation or Bayesian inference can then be applied for parameter estimation. This approach is general and is not limited to a particular failure or replacement model. We implemented this approach with a Weibull-exponential failure model and a simple constant probability replacement model. Based on this distribution assumptions, we illustrated our concept with two examples. First, we used simulated data to show how replacement causes a 'survival selection bias' and how to successfully correct for it. A second example with real data illustrates how a model can be extended to consider covariables.

  12. Improved Multi-Axial, Temperature and Time Dependent (MATT) Failure Model

    NASA Technical Reports Server (NTRS)

    Richardson, D. E.; Anderson, G. L.; Macon, D. J.

    2002-01-01

    An extensive effort has recently been completed by the Space Shuttle's Reusable Solid Rocket Motor (RSRM) nozzle program to completely characterize the effects of multi-axial loading, temperature and time on the failure characteristics of three filled epoxy adhesives (TIGA 321, EA913NA, EA946). As part of this effort, a single general failure criterion was developed that accounted for these effects simultaneously. This model was named the Multi- Axial, Temperature, and Time Dependent or MATT failure criterion. Due to the intricate nature of the failure criterion, some parameters were required to be calculated using complex equations or numerical methods. This paper documents some simple but accurate modifications to the failure criterion to allow for calculations of failure conditions without complex equations or numerical techniques.

  13. Evaluation of Control Strategies for Porcine Reproductive and Respiratory Syndrome (PRRS) in Swine Breeding Herds Using a Discrete Event Agent-Based Model

    PubMed Central

    Arruda, Andréia Gonçalves; Friendship, Robert; Carpenter, Jane; Greer, Amy; Poljak, Zvonimir

    2016-01-01

    The objective of this study was to develop a discrete event agent-based stochastic model to explore the likelihood of the occurrence of porcine reproductive and respiratory syndrome (PRRS) outbreaks in swine herds with different PRRS control measures in place. The control measures evaluated included vaccination with a modified-live attenuated vaccine and live-virus inoculation of gilts, and both were compared to a baseline scenario where no control measures were in place. A typical North American 1,000-sow farrow-to-wean swine herd was used as a model, with production and disease parameters estimated from the literature and expert opinion. The model constructed herein was not only able to capture individual animal heterogeneity in immunity to and shedding of the PRRS virus, but also the dynamic animal flow and contact structure typical in such herds under field conditions. The model outcomes included maximum number of females infected per simulation, and time at which that happened and the incidence of infected weaned piglets during the first year of challenge-virus introduction. Results showed that the baseline scenario produced a larger percentage of simulations resulting in outbreaks compared to the control scenarios, and interestingly some of the outbreaks occurred over long periods after virus introduction. The live-virus inoculation scenario showed promising results, with fewer simulations resulting in outbreaks than the other scenarios, but the negative impacts of maintaining a PRRS-positive population should be considered. Finally, under the assumptions of the current model, neither of the control strategies prevented the infection from spreading to the piglet population, which highlights the importance of maintaining internal biosecurity practices at the farrowing room level. PMID:27875546

  14. A RAT MODEL OF HEART FAILURE INDUCED BY ISOPROTERENOL AND A HIGH SALT DIET

    EPA Science Inventory

    Rat models of heart failure (HF) show varied pathology and time to disease outcome, dependent on induction method. We found that subchronic (4wk) isoproterenol (ISO) infusion in Spontaneously Hypertensive Heart Failure (SHHF) rats caused cardiac injury with minimal hypertrophy. O...

  15. Modeling Grade IV Gas Emboli using a Limited Failure Population Model with Random Effects

    NASA Technical Reports Server (NTRS)

    Thompson, Laura A.; Conkin, Johnny; Chhikara, Raj S.; Powell, Michael R.

    2002-01-01

    Venous gas emboli (VGE) (gas bubbles in venous blood) are associated with an increased risk of decompression sickness (DCS) in hypobaric environments. A high grade of VGE can be a precursor to serious DCS. In this paper, we model time to Grade IV VGE considering a subset of individuals assumed to be immune from experiencing VGE. Our data contain monitoring test results from subjects undergoing up to 13 denitrogenation test procedures prior to exposure to a hypobaric environment. The onset time of Grade IV VGE is recorded as contained within certain time intervals. We fit a parametric (lognormal) mixture survival model to the interval-and right-censored data to account for the possibility of a subset of "cured" individuals who are immune to the event. Our model contains random subject effects to account for correlations between repeated measurements on a single individual. Model assessments and cross-validation indicate that this limited failure population mixture model is an improvement over a model that does not account for the potential of a fraction of cured individuals. We also evaluated some alternative mixture models. Predictions from the best fitted mixture model indicate that the actual process is reasonably approximated by a limited failure population model.

  16. Acute Heart Failure Registry: Risk Assessment Model in Decompensated Heart Failure

    PubMed Central

    Delgado, Anne; Rodrigues, Bruno; Nunes, Sara; Baptista, Rui; Marmelo, Bruno; Moreira, Davide; Gama, Pedro; Nunes, Luís; Santos, Oliveira; Cabral, Costa

    2016-01-01

    Background Heart failure (HF) is a highly prevalent syndrome. Although the long-term prognostic factors have been identified in chronic HF, this information is scarcer with respect to patients with acute HF. despite available data in the literature on long-term prognostic factors in chronic HF, data on acute HF patients are more scarce. Objectives To develop a predictor of unfavorable prognostic events in patients hospitalized for acute HF syndromes, and to characterize a group at higher risk regarding their clinical characteristics, treatment and outcomes. Methods cohort study of 600 patients admitted for acute HF, defined according to the European Society of Cardiology criteria. Primary endpoint for score derivation was defined as all-cause mortality and / or rehospitalization for HF at 12 months. For score validation, the following endpoints were used: all-cause mortality and / or readmission for HF at 6, 12 and 24 months. The exclusion criteria were: high output HF; patients with acute myocardial infraction, acute myocarditis, infectious endocarditis, pulmonary infection, pulmonary artery hypertension and severe mitral stenosis. Results 505 patients were included, and prognostic predicting factors at 12 months were identified. One or two points were assigned according to the odds ratio (OR) obtained (p < 0.05). After the total score value was determined, a 4-point cut-off was determined for each ROC curve at 12 months. Two groups were formed according to the number of points, group A < 4 points, and group B = 4 points. Group B was composed of older patients, with higher number of comorbidities and predictors of the combined endpoint at 6, 12 and 24 months, as linearly represented in the survival curves (Log rank). Conclusions This risk score enabled the identification of a group with worse prognosis at 12 months.

  17. Lattice Discrete Particle Model (LDPM) for Failure Behavior of Concrete. 1: Theory (PREPRINT)

    DTIC Science & Technology

    2010-12-18

    Lattice Discrete Particle Model (LDPM) for Failure Behavior of Concrete. I: Theory . By Gianluca Cusatis 1, Daniele Pelessone 2, Andrea Mencarelli 3...Lattice Discrete Particle Model (LDPM) For Failure Behavior Of Concrete. I: Theory 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...proposing new multiscale theories have flourished, especially for modeling nano-composite materials and atomistic and molecular systems [23]. The same kind

  18. A Tool To Support Failure Mode And Effects Analysis Based On Causal Modelling And Reasoning

    NASA Astrophysics Data System (ADS)

    Underwood, W. E.; Laib, S. L.

    1987-05-01

    A prototype knowledge-based system has been developed that supports Failure Mode & Effects Analysis (FMEA). The knowledge base consists of causal models of components and a representation for coupling these components into assemblies and systems. The causal models are qualitative models. They allow reasoning as to whether variables are increasing, decreasing or steady. The analysis strategies used by the prototype allow it to determine the effects of failure modes on the function of the part, the failure effect on the assembly the part is contained in, and the effect on the subsystem containing the assembly.

  19. Common-Cause Failure Treatment in Event Assessment: Basis for a Proposed New Model

    SciTech Connect

    Dana Kelly; Song-Hua Shen; Gary DeMoss; Kevin Coyne; Don Marksberry

    2010-06-01

    Event assessment is an application of probabilistic risk assessment in which observed equipment failures and outages are mapped into the risk model to obtain a numerical estimate of the event’s risk significance. In this paper, we focus on retrospective assessments to estimate the risk significance of degraded conditions such as equipment failure accompanied by a deficiency in a process such as maintenance practices. In modeling such events, the basic events in the risk model that are associated with observed failures and other off-normal situations are typically configured to be failed, while those associated with observed successes and unchallenged components are assumed capable of failing, typically with their baseline probabilities. This is referred to as the failure memory approach to event assessment. The conditioning of common-cause failure probabilities for the common cause component group associated with the observed component failure is particularly important, as it is insufficient to simply leave these probabilities at their baseline values, and doing so may result in a significant underestimate of risk significance for the event. Past work in this area has focused on the mathematics of the adjustment. In this paper, we review the Basic Parameter Model for common-cause failure, which underlies most current risk modelling, discuss the limitations of this model with respect to event assessment, and introduce a proposed new framework for common-cause failure, which uses a Bayesian network to model underlying causes of failure, and which has the potential to overcome the limitations of the Basic Parameter Model with respect to event assessment.

  20. Cascades of failures in various models of interdependent networks

    NASA Astrophysics Data System (ADS)

    Buldyrev, Sergey; Kadish, Benjamin; Shere, Nathaniel; Aharon, Mitchel; Cwilich, Gabriel

    2012-02-01

    Complex networks appear in almost every aspect of science and technology. Recently an analytical framework for studying the percolation properties of interacting networks has been developed [1]. These studies however have several limitations. The real networks do are not randomly connected. They are often embedded into two dimensional space. The dependency links are not connecting nodes at random but have tendency to connect nodes with similar degrees, or nodes which are close to each other in Euclidian space. Moreover, the network failures may occur not only to the loss of connectivity but also due to overload of nodes with high betweennes. We have study these situations analytically and by computer simulations and found the conditions at which networks collapse in an abrupt first order like transition when the entire network becomes non-functional or fail gradually like in a second order transition as a greater fraction of nodes is removed in the initial attack or failure. [4pt] [1] S. V. Buldyrev, R. Parshani, G. Paul, H. E. Stanley, and S. Havlin, ``Catastrophic cascade of failures in interdependent networks,'' Nature 464, 1025-1028 (2010)

  1. Good and bad consequences of altered fatty acid metabolism in heart failure: evidence from mouse models.

    PubMed

    Abdurrachim, Desiree; Luiken, Joost J F P; Nicolay, Klaas; Glatz, Jan F C; Prompers, Jeanine J; Nabben, Miranda

    2015-05-01

    The shift in substrate preference away from fatty acid oxidation (FAO) towards increased glucose utilization in heart failure has long been interpreted as an oxygen-sparing mechanism. Inhibition of FAO has therefore evolved as an accepted approach to treat heart failure. However, recent data indicate that increased reliance on glucose might be detrimental rather than beneficial for the failing heart. This review discusses new insights into metabolic adaptations in heart failure. A particular focus lies on data obtained from mouse models with modulations of cardiac FA metabolism at different levels of the FA metabolic pathway and how these differently affect cardiac function. Based on studies in which these mouse models were exposed to ischaemic and non-ischaemic heart failure, we discuss whether and when modulations in FA metabolism are protective against heart failure.

  2. A probabilisitic based failure model for components fabricated from anisotropic graphite

    NASA Astrophysics Data System (ADS)

    Xiao, Chengfeng

    The nuclear moderator for high temperature nuclear reactors are fabricated from graphite. During reactor operations graphite components are subjected to complex stress states arising from structural loads, thermal gradients, neutron irradiation damage, and seismic events. Graphite is a quasi-brittle material. Two aspects of nuclear grade graphite, i.e., material anisotropy and different behavior in tension and compression, are explicitly accounted for in this effort. Fracture mechanic methods are useful for metal alloys, but they are problematic for anisotropic materials with a microstructure that makes it difficult to identify a "critical" flaw. In fact cracking in a graphite core component does not necessarily result in the loss of integrity of a nuclear graphite core assembly. A phenomenological failure criterion that does not rely on flaw detection has been derived that accounts for the material behaviors mentioned. The probability of failure of components fabricated from graphite is governed by the scatter in strength. The design protocols being proposed by international code agencies recognize that design and analysis of reactor core components must be based upon probabilistic principles. The reliability models proposed herein for isotropic graphite and graphite that can be characterized as being transversely isotropic are another set of design tools for the next generation very high temperature reactors (VHTR) as well as molten salt reactors. The work begins with a review of phenomenologically based deterministic failure criteria. A number of this genre of failure models are compared with recent multiaxial nuclear grade failure data. Aspects in each are shown to be lacking. The basic behavior of different failure strengths in tension and compression is exhibited by failure models derived for concrete, but attempts to extend these concrete models to anisotropy were unsuccessful. The phenomenological models are directly dependent on stress invariants. A set of

  3. Multifunctional photopolymerized semiinterpenetrating network (sIPN) system containing bupivacaine and silver sulfadiazine is an effective donor site treatment in a swine model.

    PubMed

    Faucher, Lee D; Kleinbeck, Kyle R; Kao, Weiyuan John

    2010-01-01

    Previously, we have shown in a cross-comparison study that multifunctional photopolymerized semiinterpenetrating network (sIPN) system is an effective donor site treatment in a swine model. The advantages of sIPN include spray-on application, in situ photopolymerization, and ability to cover large contoured areas. sIPN has also been shown to be an effective delivery vehicle for keratinocyte growth factor, dexamethasone, bupivacaine, and silver sulfadiazine in vitro. Our aim for this study was to show that these products delivered to the wound bed with sIPN would not change the wound healing characteristics compared with the control site through qualitative clinical evaluation and to compare the rate and quality of donor site healing through histologic evaluation. Eight Yucatan swine of 40 lbs each were randomly divided into four groups of two pigs before surgery. Each animal had 5.6% TBSA of skin harvested from two different dorsal regions, with one at 22/1000th-inch and the other at 30/1000th-inch setting on the dermatome. Each test site on each animal was then sequentially dressed with 50 cm(2) of Xeroform gauze, sIPN, sIPN loaded with 0.5% bupivacaine, or sIPN loaded with 1% silver sulfadiazine. sIPN with or without soluble drugs were applied as liquid, then photopolymerized in situ to form an elastic covering. Each of the test areas was separated by 50 cm(2) of autograft, which was used to divide the test areas. Wound assessment and killing occurred at days 7, 9, 14, and 21. A full-thickness biopsy was taken from each of the study areas for histological analysis. By 14 days, all areas showed complete epidermal coverage histologically. The 30/1000th-inch site revealed a thicker, more irregular dermis compared with the 22/1000th-site. Evaluation of the day-21 sites revealed equal thinning and flattening of the new epidermis. No site showed full restoration of the rete ridges. No signs of infection were seen in clinical or histological evaluations of any treatment

  4. Endoplasmic Reticulum Is Involved in Myocardial Injury in a Miniature Swine Model of Coronary Artery Stenosis Exposed to Acceleration-Associated Stress

    PubMed Central

    Zhang, Haitao; Chai, Meng; Liu, Chaozhong; Sun, Jinjin; Huang, Congchun; Yu, Xinya; Tian, Yi; Luo, Huilan

    2015-01-01

    This study aimed to investigate the effects of myocardial injury in a minimally-invasive miniature swine model with different levels of coronary artery stenosis (CAS) and exposed to maximal tolerated +Gz. Proximal left anterior descending branch was ligated in 20 swine. Five swine underwent a sham operation. A trapezoid acceleration curve was used for +Gz stress. Pathological changes of myocardial tissue were detected by H&E staining. Apoptotic cardiomyocytes were detected by TUNEL. GRP78 and CHOP were investigated by immunohistochemistry and western blot. CAS models were successful in 18 animals.Compared with the sham-operated group (+8.00±0.71 Gz), the maximal tolerated +Gz values of the moderate stenosis (+6.00±0.89 Gz, P<0.05) and severe stenosis groups (+5.20±0.84 Gz, P<0.05) were decreased.Compared with sham animals (12.16±1.25%), after exposure to maximum +Gz, apoptotic cells of the moderate (43.53±8.42%, P<0.05) and severe stenosis group (60.50±9.35%, P<0.05) were increased, MDA content was increased (1.89 and 4.91 folds, respectively, P<0.05), and SOD activity was reduced (-13.66% and -21.71%, respectively). After exposure to maximum +Gz, GRP78 protein expression was low in the sham-operated (0.29±0.05) and mild stenosis groups (0.35±0.04), while expression was high in the moderate (0.72±0.04, P<0.05) and severe stenosis groups (0.65±0.07, P<0.05). CHOP protein expression was not observed in the sham-operated group, while expression was high in the moderate and severe stenosis groups. These results indicated that Under maximum exposure to +Gz stress, different levels of CAS led to different levels of myocardial injury. Endoplasmic reticulum response is involved in the apoptosis of cardiomyocytes after +Gz stress. PMID:26167928

  5. Expression of Haemophilus ducreyi collagen binding outer membrane protein NcaA is required for virulence in swine and human challenge models of chancroid.

    PubMed

    Fulcher, Robert A; Cole, Leah E; Janowicz, Diane M; Toffer, Kristen L; Fortney, Kate R; Katz, Barry P; Orndorff, Paul E; Spinola, Stanley M; Kawula, Thomas H

    2006-05-01

    Haemophilus ducreyi, the etiologic agent of the sexually transmitted genital ulcer disease chancroid, has been shown to associate with dermal collagen fibers within infected skin lesions. Here we describe NcaA, a previously uncharacterized outer membrane protein that is important for H. ducreyi collagen binding and host colonization. An H. ducreyi strain lacking the ncaA gene was impaired in adherence to type I collagen but not fibronectin (plasma or cellular form) or heparin. The mutation had no effect on serum resistance or binding to HaCaT keratinocytes or human foreskin fibroblasts in vitro. Escherichia coli expressing H. ducreyi NcaA bound to type I collagen, demonstrating that NcaA is sufficient to confer collagen attachment. The importance of NcaA in H. ducreyi pathogenesis was assessed using both swine and human experimental models of chancroid. In the swine model, 20% of lesions from sites inoculated with the ncaA mutant were culture positive for H. ducreyi 7 days after inoculation, compared to 73% of wild-type-inoculated sites. The average number of CFU recovered from mutant-inoculated lesions was also significantly reduced compared to that recovered from wild-type-inoculated sites at both 2 and 7 days after inoculation. In the human challenge model, 8 of 30 sites inoculated with wild-type H. ducreyi progressed to the pustular stage, compared to 0 of 30 sites inoculated with the ncaA mutant. Together these results demonstrate that the collagen binding protein NcaA is required for H. ducreyi infection.

  6. Maternally Derived Immunity Extends Swine Influenza A Virus Persistence within Farrow-to-Finish Pig Farms: Insights from a Stochastic Event-Driven Metapopulation Model

    PubMed Central

    Cador, Charlie; Rose, Nicolas; Willem, Lander; Andraud, Mathieu

    2016-01-01

    Swine Influenza A Viruses (swIAVs) have been shown to persist in farrow-to-finish pig herds with repeated outbreaks in successive batches, increasing the risk for respiratory disorders in affected animals and being a threat for public health. Although the general routes of swIAV transmission (i.e. direct contact and exposure to aerosols) were clearly identified, the transmission process between batches is still not fully understood. Maternally derived antibodies (MDAs) were stressed as a possible factor favoring within-herd swIAV persistence. However, the relationship between MDAs and the global spread among the different subpopulations in the herds is still lacking. The aim of this study was therefore to understand the mechanisms induced by MDAs in relation with swIAV spread and persistence in farrow-to-finish pig herds. A metapopulation model has been developed representing the population dynamics considering two subpopulations—breeding sows and growing pigs—managed according to batch-rearing system. This model was coupled with a swIAV-specific epidemiological model, accounting for partial passive immunity protection in neonatal piglets and an immunity boost in re-infected animals. Airborne transmission was included by a between-room transmission rate related to the current prevalence of shedding pigs. Maternally derived partial immunity in piglets was found to extend the duration of the epidemics within their batch, allowing for efficient between-batch transmission and resulting in longer swIAV persistence at the herd level. These results should be taken into account in the design of control programmes for the spread and persistence of swIAV in swine herds. PMID:27662592

  7. Assessment of Postoperative Analgesia after Application of Ultrasound-Guided Regional Anesthesia for Surgery in a Swine Femoral Fracture Model

    PubMed Central

    Royal, Joseph M; Settle, Timothy L; Bodo, Michael; Lombardini, Eric; Kent, Michael L; Upp, Justin; Rothwell, Stephen W

    2013-01-01

    Management of pain in research swine used for studies involving painful procedures is a considerable challenge. Here we assessed whether a regional anesthesia method is effective for pain control of hindlimb injuries in pigs used for research in bone fracture healing. For this randomized controlled study, we administered regional anesthesia before an experimental femoral injury was produced. Using ultrasound guidance, we placed sterile infusion catheters near the sciatic and femoral nerves and administered local anesthetic (bupivacaine) for the first 24 h after surgery. We evaluated various behavioral and physiologic parameters to test the hypothesis that this regional anesthesia would provide superior analgesia compared with systemic analgesia alone. We also collected blood samples to evaluate serum levels of cortisol and fentanyl postoperatively. At the end of the study period, we collected sciatic and femoral nerves and surrounding soft tissues for histopathologic evaluation. Treatment pigs had lower subjective pain scores than did control animals. Control pigs had a longer time to first feed consumption and required additional analgesia earlier in the postoperative period than did treatment pigs. Ultrasound-guided regional anesthesia is a viable and effective adjunct to systemic analgesics for providing pain control in swine with experimental femoral fractures. PMID:23849409

  8. Developing a predictive risk model for first-line antiretroviral therapy failure in South Africa

    PubMed Central

    Rohr, Julia K; Ive, Prudence; Horsburgh, C Robert; Berhanu, Rebecca; Shearer, Kate; Maskew, Mhairi; Long, Lawrence; Sanne, Ian; Bassett, Jean; Ebrahim, Osman; Fox, Matthew P

    2016-01-01

    Introduction A substantial number of patients with HIV in South Africa have failed first-line antiretroviral therapy (ART). Although individual predictors of first-line ART failure have been identified, few studies in resource-limited settings have been large enough for predictive modelling. Understanding the absolute risk of first-line failure is useful for patient monitoring and for effectively targeting limited resources for second-line ART. We developed a predictive model to identify patients at the greatest risk of virologic failure on first-line ART, and to estimate the proportion of patients needing second-line ART over five years on treatment. Methods A cohort of patients aged ≥18 years from nine South African HIV clinics on first-line ART for at least six months were included. Viral load measurements and baseline predictors were obtained from medical records. We used stepwise selection of predictors in accelerated failure-time models to predict virologic failure on first-line ART (two consecutive viral load levels >1000 copies/mL). Multiple imputations were used to assign missing baseline variables. The final model was selected using internal-external cross-validation maximizing model calibration at five years on ART, and model discrimination, measured using Harrell's C-statistic. Model covariates were used to create a predictive score for risk group of ART failure. Results A total of 72,181 patients were included in the analysis, with an average of 21.5 months (IQR: 8.8–41.5) of follow-up time on first-line ART. The final predictive model had a Weibull distribution and the final predictors of virologic failure were men of all ages, young women, nevirapine use in first-line regimen, low baseline CD4 count, high mean corpuscular volume, low haemoglobin, history of TB and missed visits during the first six months on ART. About 24.4% of patients in the highest quintile and 9.4% of patients in the lowest quintile of risk were predicted to experience

  9. Why won’t you do what I want? The informative failures of children and models

    PubMed Central

    Chatham, Christopher H.; Yerys, Benjamin E.; Munakata, Yuko

    2012-01-01

    Computational models are powerful tools – too powerful, according to some. We argue that the idea that models can “do anything” is wrong, and describe how their failures have been informative. We present new work showing surprising diversity in the effects of feedback on children’s task-switching, such that some children perseverate despite this feedback, other children switch as instructed, and yet others play an “opposites” game without truly switching to the newly-instructed task. We present simulations that demonstrate the failure of an otherwise-successful neural network model to capture this failure of children. Simulating this pattern motivates the inclusion of updating mechanisms that make contact with a growing literature on frontostriatal function, despite their absence in extant theories of the development of cognitive flexibility. We argue from this and other examples that computational models are more constrained than is typically acknowledged, and that their resulting failures can be theoretically illuminating. PMID:24453404

  10. A systems approach to the policy-level risk assessment of exotic animal diseases: network model and application to classical swine fever.

    PubMed

    Delgado, João; Pollard, Simon; Snary, Emma; Black, Edgar; Prpich, George; Longhurst, Phil

    2013-08-01

    Exotic animal diseases (EADs) are characterized by their capacity to spread global distances, causing impacts on animal health and welfare with significant economic consequences. We offer a critique of current import risk analysis approaches employed in the EAD field, focusing on their capacity to assess complex systems at a policy level. To address the shortcomings identified, we propose a novel method providing a systematic analysis of the likelihood of a disease incursion, developed by reference to the multibarrier system employed for the United Kingdom. We apply the network model to a policy-level risk assessment of classical swine fever (CSF), a notifiable animal disease caused by the CSF virus. In doing so, we document and discuss a sequence of analyses that describe system vulnerabilities and reveal the critical control points (CCPs) for intervention, reducing the likelihood of U.K. pig herds being exposed to the CSF virus.

  11. Pathogenesis and Transmission of Feral Swine Pseudorabies Virus Isolates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction. Aujesky’s Disease or pseudorabies, is one of the oldest recognized swine diseases. It is caused by pseudorabies virus (PRV), an alpha-herpesvirus that can induce respiratory disease, reproductive failure, and affect the central nervous system. PRV vaccines, in conjunction with serologi...

  12. ARRA: Reconfiguring Power Systems to Minimize Cascading Failures - Models and Algorithms

    SciTech Connect

    Dobson, Ian; Hiskens, Ian; Linderoth, Jeffrey; Wright, Stephen

    2013-12-16

    Building on models of electrical power systems, and on powerful mathematical techniques including optimization, model predictive control, and simluation, this project investigated important issues related to the stable operation of power grids. A topic of particular focus was cascading failures of the power grid: simulation, quantification, mitigation, and control. We also analyzed the vulnerability of networks to component failures, and the design of networks that are responsive to and robust to such failures. Numerous other related topics were investigated, including energy hubs and cascading stall of induction machines

  13. Factors influencing the predictive power of models for predicting mortality and/or heart failure hospitalization in patients with heart failure.

    PubMed

    Ouwerkerk, Wouter; Voors, Adriaan A; Zwinderman, Aeilko H

    2014-10-01

    The present paper systematically reviews and compares existing prediction models in order to establish the strongest variables, models, and model characteristics in patients with heart failure predicting outcome. To improve decision making accurately predicting mortality and heart-failure hospitalization in patients with heart failure can be important for selecting patients with a poorer prognosis or nonresponders to current therapy, to improve decision making. MEDLINE/PubMed was searched for papers dealing with heart failure prediction models. To identify similar models on the basis of their variables hierarchical cluster analysis was performed. Meta-analysis was used to estimate the mean predictive value of the variables and models; meta-regression was used to find characteristics that explain variation in discriminating values between models. We identified 117 models in 55 papers. These models used 249 different variables. The strongest predictors were blood urea nitrogen and sodium. Four subgroups of models were identified. Mortality was most accurately predicted by prospective registry-type studies using a large number of clinical predictor variables. Mean C-statistic of all models was 0.66 ± 0.0005, with 0.71 ± 0.001, 0.68 ± 0.001 and 0.63 ± 0.001 for models predicting mortality, heart failure hospitalization, or both, respectively. There was no significant difference in discriminating value of models between patients with chronic and acute heart failure. Prediction of mortality and in particular heart failure hospitalization in patients with heart failure remains only moderately successful. The strongest predictors were blood urea nitrogen and sodium. The highest C-statistic values were achieved in a clinical setting, predicting short-term mortality with the use of models derived from prospective cohort/registry studies with a large number of predictor variables.

  14. The human subject: an integrative animal model for 21st century heart failure research

    PubMed Central

    Chandrasekera, P Charukeshi; Pippin, John J

    2015-01-01

    Heart failure remains a leading cause of death and it is a major cause of morbidity and mortality affecting tens of millions of people worldwide. Despite decades of extensive research conducted at enormous expense, only a handful of interventions have significantly impacted survival in heart failure. Even the most widely prescribed treatments act primarily to slow disease progression, do not provide sustained survival advantage, and have adverse side effects. Since mortality remains about 50% within five years of diagnosis, the need to increase our understanding of heart failure disease mechanisms and development of preventive and reparative therapies remains critical. Currently, the vast majority of basic science heart failure research is conducted using animal models ranging from fruit flies to primates; however, insights gleaned from decades of animal-based research efforts have not been proportional to research success in terms of deciphering human heart failure and developing effective therapeutics for human patients. Here we discuss the reasons for this translational discrepancy which can be equally attributed to the use of erroneous animal models and the lack of widespread use of human-based research methodologies and address why and how we must position our own species at center stage as the quintessential animal model for 21st century heart failure research. If the ultimate goal of the scientific community is to tackle the epidemic status of heart failure, the best way to achieve that goal is through prioritizing human-based, human-relevant research. PMID:26550463

  15. Cascading failures in bi-partite graphs: model for systemic risk propagation.

    PubMed

    Huang, Xuqing; Vodenska, Irena; Havlin, Shlomo; Stanley, H Eugene

    2013-01-01

    As economic entities become increasingly interconnected, a shock in a financial network can provoke significant cascading failures throughout the system. To study the systemic risk of financial systems, we create a bi-partite banking network model composed of banks and bank assets and propose a cascading failure model to describe the risk propagation process during crises. We empirically test the model with 2007 US commercial banks balance sheet data and compare the model prediction of the failed banks with the real failed banks after 2007. We find that our model efficiently identifies a significant portion of the actual failed banks reported by Federal Deposit Insurance Corporation. The results suggest that this model could be useful for systemic risk stress testing for financial systems. The model also identifies that commercial rather than residential real estate assets are major culprits for the failure of over 350 US commercial banks during 2008-2011.

  16. Cascading Failures in Bi-partite Graphs: Model for Systemic Risk Propagation

    PubMed Central

    Huang, Xuqing; Vodenska, Irena; Havlin, Shlomo; Stanley, H. Eugene

    2013-01-01

    As economic entities become increasingly interconnected, a shock in a financial network can provoke significant cascading failures throughout the system. To study the systemic risk of financial systems, we create a bi-partite banking network model composed of banks and bank assets and propose a cascading failure model to describe the risk propagation process during crises. We empirically test the model with 2007 US commercial banks balance sheet data and compare the model prediction of the failed banks with the real failed banks after 2007. We find that our model efficiently identifies a significant portion of the actual failed banks reported by Federal Deposit Insurance Corporation. The results suggest that this model could be useful for systemic risk stress testing for financial systems. The model also identifies that commercial rather than residential real estate assets are major culprits for the failure of over 350 US commercial banks during 2008–2011. PMID:23386974

  17. A Thermal Runaway Failure Model for Low-Voltage BME Ceramic Capacitors with Defects

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2017-01-01

    Reliability of base metal electrode (BME) multilayer ceramic capacitors (MLCCs) that until recently were used mostly in commercial applications, have been improved substantially by using new materials and processes. Currently, the inception of intrinsic wear-out failures in high quality capacitors became much greater than the mission duration in most high-reliability applications. However, in capacitors with defects degradation processes might accelerate substantially and cause infant mortality failures. In this work, a physical model that relates the presence of defects to reduction of breakdown voltages and decreasing times to failure has been suggested. The effect of the defect size has been analyzed using a thermal runaway model of failures. Adequacy of highly accelerated life testing (HALT) to predict reliability at normal operating conditions and limitations of voltage acceleration are considered. The applicability of the model to BME capacitors with cracks is discussed and validated experimentally.

  18. A Multiscale Progressive Failure Modeling Methodology for Composites that Includes Fiber Strength Stochastics

    NASA Technical Reports Server (NTRS)

    Ricks, Trenton M.; Lacy, Thomas E., Jr.; Bednarcyk, Brett A.; Arnold, Steven M.; Hutchins, John W.

    2014-01-01

    A multiscale modeling methodology was developed for continuous fiber composites that incorporates a statistical distribution of fiber strengths into coupled multiscale micromechanics/finite element (FE) analyses. A modified two-parameter Weibull cumulative distribution function, which accounts for the effect of fiber length on the probability of failure, was used to characterize the statistical distribution of fiber strengths. A parametric study using the NASA Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC) was performed to assess the effect of variable fiber strengths on local composite failure within a repeating unit cell (RUC) and subsequent global failure. The NASA code FEAMAC and the ABAQUS finite element solver were used to analyze the progressive failure of a unidirectional SCS-6/TIMETAL 21S metal matrix composite tensile dogbone specimen at 650 degC. Multiscale progressive failure analyses were performed to quantify the effect of spatially varying fiber strengths on the RUC-averaged and global stress-strain responses and failure. The ultimate composite strengths and distribution of failure locations (predominately within the gage section) reasonably matched the experimentally observed failure behavior. The predicted composite failure behavior suggests that use of macroscale models that exploit global geometric symmetries are inappropriate for cases where the actual distribution of local fiber strengths displays no such symmetries. This issue has not received much attention in the literature. Moreover, the model discretization at a specific length scale can have a profound effect on the computational costs associated with multiscale simulations.models that yield accurate yet tractable results.

  19. Development of A Tabulated Thermo-Viscoplastic Material Model with Regularized Failure for Dynamic Ductile Failure Prediction of Structures under Impact Loading

    NASA Astrophysics Data System (ADS)

    Buyuk, Murat

    It is important to understand the dynamic failure behavior of structures subjected to impact loading in order to improve the survivability. Materials under impact are utterly affected by large deformations, high strain-rates, temperature softening and varying stress-states, which finally may lead to failure. It is shown that the impact characteristics are prone to change with several independent factors such as; impact speed, material thickness, and shape and orientation of the impacting object. Validated numerical simulations of impact tests reveal that the failure on ductile metals occur at certain locations of the failure locus that is constructed on a space as a function of all three stress invariants, which indicates that the failure depends profoundly on the state-of-stress. It is shown that existing material models are not always successful enough to cover the whole range of the failure locus and predict the failure. Therefore, it is a common practice to use different sets of material model parameters tuned or calibrated to cover a specific region of the failure loci in an ad hoc manner for practical reasons to match particular test results. Even in that case, specially tuned material properties are not capable of predicting these limited cases if differences in the mesh size and pattern need to be considered. In this dissertation a new, generic, thermo-elastic/viscoplastic material model with regularized failure is introduced. The new material model is implemented into a non-linear, explicit dynamics finite element code, LS-DYNA. A von Mises type isotropic, isochoric plasticity is utilized, where isotropic hardening, strain-rate hardening and temperature softening is considered. The model takes adiabatic heating and softening into account due to the plastic work. The constitutive relation is coupled with a new regularized accumulated failure law that is specifically developed to cover a large extent of the failure locus as a function of state

  20. Predictors of resuscitation outcome in a swine model of VF cardiac arrest: A comparison of VF duration, presence of acute myocardial infarction and VF waveform☆,☆☆

    PubMed Central

    Indik, Julia H.; Shanmugasundaram, Madhan; Allen, Daniel; Valles, Amanda; Kern, Karl B.; Hilwig, Ronald W.; Zuercher, Mathias; Berg, Robert A.

    2012-01-01

    Introduction Factors that affect resuscitation to a perfusing rhythm (ROSC) following ventricular fibrillation (VF) include untreated VF duration, acute myocardial infarction (AMI), and possibly factors reflected in the VF waveform. We hypothesized that resuscitation of VF to ROSC within 3 min is predicted by the VF waveform, independent of untreated VF duration or presence of acute MI. Methods AMI was induced by the occlusion of the left anterior descending coronary artery. VF was induced in normal (N = 30) and AMI swine (N = 30). Animals were resuscitated after untreated VF of brief (2 min) or prolonged (8 min) duration. VF waveform was analyzed before the first shock to compute the amplitude-spectral area (AMSA) and slope. Results Unadjusted predictors of ROSC within 3 min included untreated VF duration (8 min vs 2 min; OR 0.11, 95%CI 0.02–0.54), AMI (AMI vs normal; OR 0.11, 95%CI 0.02–0.54), AMSA (highest to lowest tertile; OR 15.5, 95%CI 1.7–140), and slope (highest to lowest tertile; OR 12.7, 95%CI 1.4–114). On multivariate regression, untreated VF duration (P = 0.011) and AMI (P = 0.003) predicted ROSC within 3 min. Among secondary outcome variables, favorable neurological status at 24 h was only predicted by VF duration (OR 0.22, 95% CI 0.05–0.92). Conclusions In this swine model of VF, untreated VF duration and AMI were independent predictors of ROSC following VF cardiac arrest. AMSA and slope predicted ROSC when VF duration or the presence of AMI were unknown. Importantly, the initial treatment of choice for short duration VF is defibrillation regardless of VF waveform. PMID:19804932

  1. Swine influenza H1N1 virus induces acute inflammatory immune responses in pig lungs: a potential animal model for human H1N1 influenza virus.

    PubMed

    Khatri, Mahesh; Dwivedi, Varun; Krakowka, Steven; Manickam, Cordelia; Ali, Ahmed; Wang, Leyi; Qin, Zhuoming; Renukaradhya, Gourapura J; Lee, Chang-Won

    2010-11-01

    Pigs are capable of generating reassortant influenza viruses of pandemic potential, as both the avian and mammalian influenza viruses can infect pig epithelial cells in the respiratory tract. The source of the current influenza pandemic is H1N1 influenza A virus, possibly of swine origin. This study was conducted to understand better the pathogenesis of H1N1 influenza virus and associated host mucosal immune responses during acute infection in humans. Therefore, we chose a H1N1 swine influenza virus, Sw/OH/24366/07 (SwIV), which has a history of transmission to humans. Clinically, inoculated pigs had nasal discharge and fever and shed virus through nasal secretions. Like pandemic H1N1, SwIV also replicated extensively in both the upper and lower respiratory tracts, and lung lesions were typical of H1N1 infection. We detected innate, proinflammatory, Th1, Th2, and Th3 cytokines, as well as SwIV-specific IgA antibody in lungs of the virus-inoculated pigs. Production of IFN-γ by lymphocytes of the tracheobronchial lymph nodes was also detected. Higher frequencies of cytotoxic T lymphocytes, γδ T cells, dendritic cells, activated T cells, and CD4+ and CD8+ T cells were detected in SwIV-infected pig lungs. Concomitantly, higher frequencies of the immunosuppressive T regulatory cells were also detected in the virus-infected pig lungs. The findings of this study have relevance to pathogenesis of the pandemic H1N1 influenza virus in humans; thus, pigs may serve as a useful animal model to design and test effective mucosal vaccines and therapeutics against influenza virus.

  2. The Utility of the Swine Model to Assess Biological Rhythms and Their Characteristics during Different Stages of Residence in a Simulated Intensive Care Unit: A Pilot Study

    PubMed Central

    Leyden, Katrina N.; Hanneman, Sandra K.; Padhye, Nikhil S.; Smolensky, Michael H.; Kang, Duck-Hee; Chow, Diana Shu-Lian

    2016-01-01

    The purpose of this pilot study was to explore the utility of the mammalian swine model under simulated intensive care unit (sICU) conditions and mechanical ventilation for assessment of the trajectory of circadian rhythms of sedation requirement, core body temperature (CBT), pulmonary mechanics (PM), and gas exchange (GE). Data were collected prospectively with an observational time-series design to describe and compare circadian rhythms of selected study variables in four swine mechanically ventilated for up to 7 consecutive days. We derived the circadian (total variance explained by rhythms of τ between 20–28 h)/ultradian (total variance explained by rhythms of τ between 1 to <20 h) bandpower ratio to assess the robustness of circadian rhythms, and compare findings between the early (first 3 days) and late (subsequent days) sICU stay. All pigs exhibited statistically significant circadian rhythms (τ between 20–28 h) in CBT, respiratory rate, and peripheral oxygen saturation, but circadian rhythms were detected less frequently for sedation requirement, spontaneous minute volume, arterial oxygen tension, arterial carbon dioxide tension, and arterial pH. Sedation did not appear to mask the circadian rhythms of CBT, PM, and GE. Individual subject observations were more informative than group data, and provided preliminary evidence that (a) circadian rhythms of multiple variables are lost or desynchronized in mechanically ventilated subjects, (b) robustness of circadian rhythm varies with subject morbidity, and (c) healthier pigs develop more robust circadian rhythm profiles over time in the sICU. Comparison of biological rhythm profiles among sICU subjects with similar severity of illness is needed to determine if the results of this pilot study are reproducible. Identification of consistent patterns may provide insight into subject morbidity and timing of such therapeutic interventions as weaning from mechanical ventilation. PMID:26204131

  3. Intracoronary artery transplantation of cardiomyoblast-like cells from human adipose tissue-derived multi-lineage progenitor cells improve left ventricular dysfunction and survival in a swine model of chronic myocardial infarction.

    PubMed

    Okura, Hanayuki; Saga, Ayami; Soeda, Mayumi; Miyagawa, Shigeru; Sawa, Yoshiki; Daimon, Takashi; Ichinose, Akihiro; Matsuyama, Akifumi

    2012-09-07

    Transplantation of human cardiomyoblast-like cells (hCLCs) from human adipose tissue-derived multi-lineage progenitor cells improved left ventricular function and survival of rats with myocardial infarction. Here we examined the effect of intracoronary artery transplantation of human CLCs in a swine model of chronic heart failure. Twenty-four pigs underwent balloon-occlusion of the first diagonal branch followed by reperfusion, with a second balloon-occlusion of the left ascending coronary artery 1 week later followed by reperfusion. Four weeks after the second occlusion/reperfusion, 17 of the 18 surviving animals with severe chronic MI (ejection fraction <35% by echocardiography) were immunosuppressed then randomly assigned to receive either intracoronary artery transplantation of hCLCs hADMPCs or placebo lactic Ringer's solution with heparin. Intracoronary artery transplantation was followed by the distribution of DiI-stained hCLCs into the scarred myocardial milieu. Echocardiography at post-transplant days 4 and 8 weeks showed rescue and maintenance of cardiac function in the hCLCs transplanted group, but not in the control animals, indicating myocardial functional recovery by hCLCs intracoronary transplantation. At 8 week post-transplantation, 7 of 8 hCLCs transplanted animals were still alive compared with only 1 of the 5 control (p=0.0147). Histological studies at week 12 post-transplantation demonstrated engraftment of the pre DiI-stained hCLCs into the scarred myocardium and their expression of human specific alpha-cardiac actin. Human alpha cardiac actin-positive cells also expressed cardiac nuclear factors; nkx2.5 and GATA-4. Our results suggest that intracoronary artery transplantation of hCLCs is a potentially effective therapeutic strategy for future cardiac tissue regeneration.

  4. The Influence of a High Salt Diet on a Rat Model of Isoproterenol-Induced Heart Failure

    EPA Science Inventory

    Rat models of heart failure (HF) show varied pathology and time to disease outcome, dependent on induction method. We found that subchronic (4 weeks) isoproterenol (ISO) infusion exacerbated cardiomyopathy in Spontaneously Hypertensive Heart Failure (SHHF) rats. Others have shown...

  5. Real time detection of farm-level swine mycobacteriosis outbreak using time series modeling of the number of condemned intestines in abattoirs

    PubMed Central

    ADACHI, Yasumoto; MAKITA, Kohei

    2015-01-01

    Mycobacteriosis in swine is a common zoonosis found in abattoirs during meat inspections, and the veterinary authority is expected to inform the producer for corrective actions when an outbreak is detected. The expected value of the number of condemned carcasses due to mycobacteriosis therefore would be a useful threshold to detect an outbreak, and the present study aims to develop such an expected value through time series modeling. The model was developed using eight years of inspection data (2003 to 2010) obtained at 2 abattoirs of the Higashi-Mokoto Meat Inspection Center, Japan. The resulting model was validated by comparing the predicted time-dependent values for the subsequent 2 years with the actual data for 2 years between 2011 and 2012. For the modeling, at first, periodicities were checked using Fast Fourier Transformation, and the ensemble average profiles for weekly periodicities were calculated. An Auto-Regressive Integrated Moving Average (ARIMA) model was fitted to the residual of the ensemble average on the basis of minimum Akaike’s information criterion (AIC). The sum of the ARIMA model and the weekly ensemble average was regarded as the time-dependent expected value. During 2011 and 2012, the number of whole or partial condemned carcasses exceeded the 95% confidence interval of the predicted values 20 times. All of these events were associated with the slaughtering of pigs from three producers with the highest rate of condemnation due to mycobacteriosis. PMID:25913899

  6. Experiments for calibration and validation of plasticity and failure material modeling: 304L stainless steel.

    SciTech Connect

    Lee, Kenneth L.; Korellis, John S.; McFadden, Sam X.

    2006-01-01

    Experimental data for material plasticity and failure model calibration and validation were obtained from 304L stainless steel. Model calibration data were taken from smooth tension, notched tension, and compression tests. Model validation data were provided from experiments using thin-walled tube specimens subjected to path dependent combinations of internal pressure, extension, and torsion.

  7. Numerical Modeling in Geodynamics: Success, Failure and Perspective

    NASA Astrophysics Data System (ADS)

    Ismail-Zadeh, A.

    2005-12-01

    A real success in numerical modeling of dynamics of the Earth can be achieved only by multidisciplinary research teams of experts in geodynamics, applied and pure mathematics, and computer science. The success in numerical modeling is based on the following basic, but simple, rules. (i) People need simplicity most, but they understand intricacies best (B. Pasternak, writer). Start from a simple numerical model, which describes basic physical laws by a set of mathematical equations, and move then to a complex model. Never start from a complex model, because you cannot understand the contribution of each term of the equations to the modeled geophysical phenomenon. (ii) Study the numerical methods behind your computer code. Otherwise it becomes difficult to distinguish true and erroneous solutions to the geodynamic problem, especially when your problem is complex enough. (iii) Test your model versus analytical and asymptotic solutions, simple 2D and 3D model examples. Develop benchmark analysis of different numerical codes and compare numerical results with laboratory experiments. Remember that the numerical tool you employ is not perfect, and there are small bugs in every computer code. Therefore the testing is the most important part of your numerical modeling. (iv) Prove (if possible) or learn relevant statements concerning the existence, uniqueness and stability of the solution to the mathematical and discrete problems. Otherwise you can solve an improperly-posed problem, and the results of the modeling will be far from the true solution of your model problem. (v) Try to analyze numerical models of a geological phenomenon using as less as possible tuning model variables. Already two tuning variables give enough possibilities to constrain your model well enough with respect to observations. The data fitting sometimes is quite attractive and can take you far from a principal aim of your numerical modeling: to understand geophysical phenomena. (vi) If the number of

  8. A Comparison of Functional Models for Use in the Function-Failure Design Method

    NASA Technical Reports Server (NTRS)

    Stock, Michael E.; Stone, Robert B.; Tumer, Irem Y.

    2006-01-01

    When failure analysis and prevention, guided by historical design knowledge, are coupled with product design at its conception, shorter design cycles are possible. By decreasing the design time of a product in this manner, design costs are reduced and the product will better suit the customer s needs. Prior work indicates that similar failure modes occur with products (or components) with similar functionality. To capitalize on this finding, a knowledge base of historical failure information linked to functionality is assembled for use by designers. One possible use for this knowledge base is within the Elemental Function-Failure Design Method (EFDM). This design methodology and failure analysis tool begins at conceptual design and keeps the designer cognizant of failures that are likely to occur based on the product s functionality. The EFDM offers potential improvement over current failure analysis methods, such as FMEA, FMECA, and Fault Tree Analysis, because it can be implemented hand in hand with other conceptual design steps and carried throughout a product s design cycle. These other failure analysis methods can only truly be effective after a physical design has been completed. The EFDM however is only as good as the knowledge base that it draws from, and therefore it is of utmost importance to develop a knowledge base that will be suitable for use across a wide spectrum of products. One fundamental question that arises in using the EFDM is: At what level of detail should functional descriptions of components be encoded? This paper explores two approaches to populating a knowledge base with actual failure occurrence information from Bell 206 helicopters. Functional models expressed at various levels of detail are investigated to determine the necessary detail for an applicable knowledge base that can be used by designers in both new designs as well as redesigns. High level and more detailed functional descriptions are derived for each failed component based

  9. Modeling Soft Tissue Damage and Failure Using a Combined Particle/Continuum Approach.

    PubMed

    Rausch, M K; Karniadakis, G E; Humphrey, J D

    2017-02-01

    Biological soft tissues experience damage and failure as a result of injury, disease, or simply age; examples include torn ligaments and arterial dissections. Given the complexity of tissue geometry and material behavior, computational models are often essential for studying both damage and failure. Yet, because of the need to account for discontinuous phenomena such as crazing, tearing, and rupturing, continuum methods are limited. Therefore, we model soft tissue damage and failure using a particle/continuum approach. Specifically, we combine continuum damage theory with Smoothed Particle Hydrodynamics (SPH). Because SPH is a meshless particle method, and particle connectivity is determined solely through a neighbor list, discontinuities can be readily modeled by modifying this list. We show, for the first time, that an anisotropic hyperelastic constitutive model commonly employed for modeling soft tissue can be conveniently implemented within a SPH framework and that SPH results show excellent agreement with analytical solutions for uniaxial and biaxial extension as well as finite element solutions for clamped uniaxial extension in 2D and 3D. We further develop a simple algorithm that automatically detects damaged particles and disconnects the spatial domain along rupture lines in 2D and rupture surfaces in 3D. We demonstrate the utility of this approach by simulating damage and failure under clamped uniaxial extension and in a peeling experiment of virtual soft tissue samples. In conclusion, SPH in combination with continuum damage theory may provide an accurate and efficient framework for modeling damage and failure in soft tissues.

  10. Modeling Stress Strain Relationships and Predicting Failure Probabilities For Graphite Core Components

    SciTech Connect

    Duffy, Stephen

    2013-09-09

    This project will implement inelastic constitutive models that will yield the requisite stress-strain information necessary for graphite component design. Accurate knowledge of stress states (both elastic and inelastic) is required to assess how close a nuclear core component is to failure. Strain states are needed to assess deformations in order to ascertain serviceability issues relating to failure, e.g., whether too much shrinkage has taken place for the core to function properly. Failure probabilities, as opposed to safety factors, are required in order to capture the bariability in failure strength in tensile regimes. The current stress state is used to predict the probability of failure. Stochastic failure models will be developed that can accommodate possible material anisotropy. This work will also model material damage (i.e., degradation of mechanical properties) due to radiation exposure. The team will design tools for components fabricated from nuclear graphite. These tools must readily interact with finite element software--in particular, COMSOL, the software algorithm currently being utilized by the Idaho National Laboratory. For the eleastic response of graphite, the team will adopt anisotropic stress-strain relationships available in COMSO. Data from the literature will be utilized to characterize the appropriate elastic material constants.

  11. Agriculture. Swine Livestock.

    ERIC Educational Resources Information Center

    Michigan State Univ., East Lansing. Coll. of Agriculture and Natural Resources Education Inst.

    This task-based curriculum guide for agricultural production, specifically for swine, is intended to help the teacher develop a classroom management system where students learn by doing. Introductory materials include a Dictionary of Occupational Titles job code and title sheet, a task sheet for developing leadership skills, and a task list. Each…

  12. Swine Brucellosis: Current Perspectives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Brucella suis is a significant zoonosis that is present in domestic livestock and wildlife in many countries worldwide. Transmission from animal reservoirs is the source of human infection as human to human transmission is very rare. Although swine brucellosis causes economic losses in domestic liv...

  13. Modeling the Progressive Failure of Jointed Rock Slope Using Fracture Mechanics and the Strength Reduction Method

    NASA Astrophysics Data System (ADS)

    Zhang, Ke; Cao, Ping; Meng, Jingjing; Li, Kaihui; Fan, Wenchen

    2015-03-01

    The fracturing process during the progressive failure of a jointed rock slope is numerically investigated by using fracture mechanics and the strength reduction method (SRM). A displacement discontinuity method containing frictional elements is developed for the calculation of the stress intensity factor (SIF). The failure initiation of the jointed rock slope is analyzed by evaluating the SIF. A new joint model is proposed by combining solid elements with interface elements in the commercial software FLAC3D. These represent the discontinuous planes in a rock mass on which sliding or separation can occur. The progressive failure process is simulated by reducing the shear strength of the rock mass, which includes the process of stress concentration, crack initiation, crack propagation, slip weakening, and coalescence of failure surfaces. The factor of safety (FS) and location of the critical failure surface are determined by the SRM. The influence of the joint inclination is investigated using the FS and the SIF. Laboratory experiments on specimens containing an inclined flaw under compression-shear stress are also conducted to investigate the effect of the angle between the shear direction and the flaw inclination, which provides an experimental explanation for the shear behavior of jointed rock. The results show that the joint inclination dominates the failure behavior of jointed rock slope, and two failure patterns have been classified.

  14. Using the failure mode and effects analysis model to improve parathyroid hormone and adrenocorticotropic hormone testing

    PubMed Central

    Magnezi, Racheli; Hemi, Asaf; Hemi, Rina

    2016-01-01

    Background Risk management in health care systems applies to all hospital employees and directors as they deal with human life and emergency routines. There is a constant need to decrease risk and increase patient safety in the hospital environment. The purpose of this article is to review the laboratory testing procedures for parathyroid hormone and adrenocorticotropic hormone (which are characterized by short half-lives) and to track failure modes and risks, and offer solutions to prevent them. During a routine quality improvement review at the Endocrine Laboratory in Tel Hashomer Hospital, we discovered these tests are frequently repeated unnecessarily due to multiple failures. The repetition of the tests inconveniences patients and leads to extra work for the laboratory and logistics personnel as well as the nurses and doctors who have to perform many tasks with limited resources. Methods A team of eight staff members accompanied by the Head of the Endocrine Laboratory formed the team for analysis. The failure mode and effects analysis model (FMEA) was used to analyze the laboratory testing procedure and was designed to simplify the process steps and indicate and rank possible failures. Results A total of 23 failure modes were found within the process, 19 of which were ranked by level of severity. The FMEA model prioritizes failures by their risk priority number (RPN). For example, the most serious failure was the delay after the samples were collected from the department (RPN =226.1). Conclusion This model helped us to visualize the process in a simple way. After analyzing the information, solutions were proposed to prevent failures, and a method to completely avoid the top four problems was also developed. PMID:27980440

  15. Finite Element Model for Failure Study of Two-Dimensional Triaxially Braided Composite

    NASA Technical Reports Server (NTRS)

    Li, Xuetao; Binienda, Wieslaw K.; Goldberg, Robert K.

    2010-01-01

    A new three-dimensional finite element model of two-dimensional triaxially braided composites is presented in this paper. This meso-scale modeling technique is used to examine and predict the deformation and damage observed in tests of straight sided specimens. A unit cell based approach is used to take into account the braiding architecture as well as the mechanical properties of the fiber tows, the matrix and the fiber tow-matrix interface. A 0 deg / plus or minus 60 deg. braiding configuration has been investigated by conducting static finite element analyses. Failure initiation and progressive degradation has been simulated in the fiber tows by use of the Hashin failure criteria and a damage evolution law. The fiber tow-matrix interface was modeled by using a cohesive zone approach to capture any fiber-matrix debonding. By comparing the analytical results to those obtained experimentally, the applicability of the developed model was assessed and the failure process was investigated.

  16. An elastic failure model of indentation damage. [of brittle structural ceramics

    NASA Technical Reports Server (NTRS)

    Liaw, B. M.; Kobayashi, A. S.; Emery, A. F.

    1984-01-01

    A mechanistically consistent model for indentation damage based on elastic failure at tensile or shear overloads, is proposed. The model accommodates arbitrary crack orientation, stress relaxation, reduction and recovery of stiffness due to crack opening and closure, and interfacial friction due to backward sliding of closed cracks. This elastic failure model was implemented by an axisymmetric finite element program which was used to simulate progressive damage in a silicon nitride plate indented by a tungsten carbide sphere. The predicted damage patterns and the permanent impression matched those observed experimentally. The validation of this elastic failure model shows that the plastic deformation postulated by others is not necessary to replicate the indentation damage of brittle structural ceramics.

  17. A review of failure models for unidirectional ceramic matrix composites under monotonic loads

    NASA Technical Reports Server (NTRS)

    Tripp, David E.; Hemann, John H.; Gyekenyesi, John P.

    1989-01-01

    Ceramic matrix composites offer significant potential for improving the performance of turbine engines. In order to achieve their potential, however, improvements in design methodology are needed. In the past most components using structural ceramic matrix composites were designed by trial and error since the emphasis of feasibility demonstration minimized the development of mathematical models. To understand the key parameters controlling response and the mechanics of failure, the development of structural failure models is required. A review of short term failure models with potential for ceramic matrix composite laminates under monotonic loads is presented. Phenomenological, semi-empirical, shear-lag, fracture mechanics, damage mechanics, and statistical models for the fast fracture analysis of continuous fiber unidirectional ceramic matrix composites under monotonic loads are surveyed.

  18. Predicting remaining life by fusing the physics of failure modeling with diagnostics

    NASA Astrophysics Data System (ADS)

    Kacprzynski, G. J.; Sarlashkar, A.; Roemer, M. J.; Hess, A.; Hardman, B.

    2004-03-01

    Technology that enables failure prediction of critical machine components (prognostics) has the potential to significantly reduce maintenance costs and increase availability and safety. This article summarizes a research effort funded through the U.S. Defense Advanced Research Projects Agency and Naval Air System Command aimed at enhancing prognostic accuracy through more advanced physics-of-failure modeling and intelligent utilization of relevant diagnostic information. H-60 helicopter gear is used as a case study to introduce both stochastic sub-zone crack initiation and three-dimensional fracture mechanics lifing models along with adaptive model updating techniques for tuning key failure mode variables at a local material/damage site based on fused vibration features. The overall prognostic scheme is aimed at minimizing inherent modeling and operational uncertainties via sensed system measurements that evolve as damage progresses.

  19. Replications of a Dual Failure Model for Boys' Depressed Mood.

    ERIC Educational Resources Information Center

    Patterson, G. R.; Stoolmiller, Mike

    1991-01-01

    Examined structural equation model for depressed mood for three samples of boys (n=317) from at-risk families. Model accounted for from 51 percent to 68 percent of variance in criterion construct. Hypothesized negative path coefficients from good peer relations construct to depressed mood construct were significant; path from academic skills…

  20. Successes and failures of the constituent quark model

    SciTech Connect

    Lipkin, H.J.

    1982-01-01

    Our approach considers the model as a possible bridge between QCD and the experimental data and examines its predictions to see where these succeed and where they fail. We also attempt to improve the model by looking for additional simple assumptions which give better fits to the experimental data. But we avoid complicated models with too many ad hoc assumptions and too many free parameters; these can fit everything but teach us nothing. We define our constituent quark model by analogy with the constituent electron model of the atom and the constituent nucleon model of the nucleus. In the same way that an atom is assumed to consist only of constituent electrons and a central Coulomb field and a nucleus is assumed to consist only of constituent nucleons hadrons are assumed to consist only of their constituent valence quarks with no bag, no glue, no ocean, nor other constituents. Although these constituent models are oversimplified and neglect other constituents we push them as far as we can. Atomic physics has photons and vacuum polarization as well as constituent electrons, but the constituent model is adequate for calculating most features of the spectrum when finer details like the Lamb shift are neglected. 54 references.

  1. Stopping the Cycle of Failure: The Comer Model.

    ERIC Educational Resources Information Center

    Ramirez-Smith, Christina

    1995-01-01

    The Comer Model is the catalyst that helped turn around a Newport News, Virginia, primary school. Founded by James Comer in the late 1960s, the model stresses schooling's main purpose--advancing students' social, emotional, academic development toward the goal of successful citizenship. This can be achieved through a collaborative,…

  2. Electrophysiology of Heart Failure Using a Rabbit Model: From the Failing Myocyte to Ventricular Fibrillation

    PubMed Central

    Liu, Michael; Qu, Zhilin; Weiss, James N.; Ennis, Daniel B.; Klug, William S.; Garfinkel, Alan

    2016-01-01

    Heart failure is a leading cause of death, yet its underlying electrophysiological (EP) mechanisms are not well understood. In this study, we use a multiscale approach to analyze a model of heart failure and connect its results to features of the electrocardiogram (ECG). The heart failure model is derived by modifying a previously validated electrophysiology model for a healthy rabbit heart. Specifically, in accordance with the heart failure literature, we modified the cell EP by changing both membrane currents and calcium handling. At the tissue level, we modeled the increased gap junction lateralization and lower conduction velocity due to downregulation of Connexin 43. At the biventricular level, we reduced the apex-to-base and transmural gradients of action potential duration (APD). The failing cell model was first validated by reproducing the longer action potential, slower and lower calcium transient, and earlier alternans characteristic of heart failure EP. Subsequently, we compared the electrical wave propagation in one dimensional cables of healthy and failing cells. The validated cell model was then used to simulate the EP of heart failure in an anatomically accurate biventricular rabbit model. As pacing cycle length decreases, both the normal and failing heart develop T-wave alternans, but only the failing heart shows QRS alternans (although moderate) at rapid pacing. Moreover, T-wave alternans is significantly more pronounced in the failing heart. At rapid pacing, APD maps show areas of conduction block in the failing heart. Finally, accelerated pacing initiated wave reentry and breakup in the failing heart. Further, the onset of VF was not observed with an upregulation of SERCA, a potential drug therapy, using the same protocol. The changes introduced at the cell and tissue level have increased the failing heart’s susceptibility to dynamic instabilities and arrhythmias under rapid pacing. However, the observed increase in arrhythmogenic potential is

  3. A model for predicting embankment slope failures in clay-rich soils; A Louisiana example

    NASA Astrophysics Data System (ADS)

    Burns, S. F.

    2015-12-01

    A model for predicting embankment slope failures in clay-rich soils; A Louisiana example It is well known that smectite-rich soils significantly reduce the stability of slopes. The question is how much smectite in the soil causes slope failures. A study of over 100 sites in north and south Louisiana, USA, compared slopes that failed during a major El Nino winter (heavy rainfall) in 1982-1983 to similar slopes that did not fail. Soils in the slopes were tested for per cent clay, liquid limits, plasticity indices and semi-quantitative clay mineralogy. Slopes with the High Risk for failure (85-90% chance of failure in 8-15 years after construction) contained soils with a liquid limit > 54%, a plasticity index over 29%, and clay contents > 47%. Slopes with an Intermediate Risk (55-50% chance of failure in 8-15 years) contained soils with a liquid limit between 36-54%, plasticity index between 16-19%, and clay content between 32-47%. Slopes with a Low Risk chance of failure (< 5% chance of failure in 8-15 years after construction) contained soils with a liquid limit < 36%, a plasticity index < 16%, and a clay content < 32%. These data show that if one is constructing embankments and one wants to prevent slope failure of the 3:1 slopes, check the above soil characteristics before construction. If the soils fall into the Low Risk classification, construct the embankment normally. If the soils fall into the High Risk classification, one will need to use lime stabilization or heat treatments to prevent failures. Soils in the Intermediate Risk class will have to be evaluated on a case by case basis.

  4. Hemoglobin-based Oxygen Carrier (HBOC-201) and Escalating Doses of Recombinant Factor VIla (rFVIIa) as a Novel Pre-hospital Resuscitation Fluid in a Swine Model of Severe Uncontrolled Hemorrhage

    DTIC Science & Technology

    2011-01-01

    past which further addition of rFVIIa may have not enhanced clotting kinetics in the absence of traumatic hypothermic coagulopathy and some plasma...possible tamponade effects in the closed abdomen are not consid- ered in this model. Third, animals were anesthetized when injured, thus abrogating the...A. D., Majetschak, M. & Proctor, K. G. (2006). Prehospital HBOC-20 1 after traumatic brain injury and hemorrhagic shock in swine. J Trauma 61:46-56

  5. A Modeling Technique and Representation of Failure in the Analysis of Triaxial Braided Carbon Fiber Composites

    NASA Technical Reports Server (NTRS)

    Littell, Justin D.; Binienda, Wieslaw K.; Goldberg, Robert K.; Roberts, Gary D.

    2008-01-01

    Quasi-static tests have been performed on triaxially braided carbon fiber composite materials with large unit cell sizes. The effects of different fibers and matrix materials on the failure mode were investigated. Simulations of the tests have been performed using the transient dynamic finite element code, LS-DYNA. However, the wide range of failure modes observed for the triaxial braided carbon fiber composites during tests could not be simulated using composite material models currently available within LS-DYNA. A macroscopic approach has been developed that provides better simulation of the material response in these materials. This approach uses full-field optical measurement techniques to measure local failures during quasi-static testing. Information from these experiments is then used along with the current material models available in LS-DYNA to simulate the influence of the braided architecture on the failure process. This method uses two-dimensional shell elements with integration points through the thickness of the elements to represent the different layers of braid along with a new analytical method for the import of material stiffness and failure data directly. The present method is being used to examine the effect of material properties on the failure process. The experimental approaches used to obtain the required data will be described, and preliminary results of the numerical analysis will be presented.

  6. Creating a Learning Flow: A Hybrid Course Model for High-Failure-Rate Math Classes

    ERIC Educational Resources Information Center

    Stevenson, Katherine; Zweier, Louis

    2011-01-01

    Higher education in the United States is facing a failure-rate crisis in entry-level mathematics courses. In this article, the authors describe an innovative, technology-enhanced hybrid course model that has significantly improved course completion and content mastery outcomes in general education (GE) mathematics courses. The model relies on five…

  7. Why Won't You Do What I Want? The Informative Failures of Children and Models

    ERIC Educational Resources Information Center

    Chatham, Christopher H.; Yerys, Benjamin E.; Munakata, Yuko

    2012-01-01

    Computational models are powerful tools--too powerful, according to some. We argue that the idea that models can "do anything" is wrong, and we describe how their failures have been informative. We present new work showing surprising diversity in the effects of feedback on children's task-switching, such that some children perseverate despite this…

  8. Cascading failures coupled model of interdependent double layered public transit network

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Fu, Bai-Bai; Li, Shu-Bin

    2016-06-01

    Taking urban public transit network as research perspective, this work introduces the influences of adjacent stations on definition of station initial load, the connected edge transit capacity, and the coupled capacity to modify traditional load-capacity cascading failures (CFs) model. Furthermore, we consider the coupled effect of lower layered public transit network on the CFs of upper layered public transit network, and construct CFs coupled model of double layered public transit network with “interdependent relationship”. Finally, taking Jinan city’s public transit network as example, we give the dynamics simulation analysis of CFs under different control parameters based on measurement indicator of station cascading failures ratio (abbreviated as CF) and the scale of time-step cascading failures (abbreviated as TCFl), get the influencing characteristics of various control parameters, and verify the feasibility of CFs coupled model of double layered public transit network.

  9. Development of a subway operation incident delay model using accelerated failure time approaches.

    PubMed

    Weng, Jinxian; Zheng, Yang; Yan, Xuedong; Meng, Qiang

    2014-12-01

    This study aims to develop a subway operational incident delay model using the parametric accelerated time failure (AFT) approach. Six parametric AFT models including the log-logistic, lognormal and Weibull models, with fixed and random parameters are built based on the Hong Kong subway operation incident data from 2005 to 2012, respectively. In addition, the Weibull model with gamma heterogeneity is also considered to compare the model performance. The goodness-of-fit test results show that the log-logistic AFT model with random parameters is most suitable for estimating the subway incident delay. First, the results show that a longer subway operation incident delay is highly correlated with the following factors: power cable failure, signal cable failure, turnout communication disruption and crashes involving a casualty. Vehicle failure makes the least impact on the increment of subway operation incident delay. According to these results, several possible measures, such as the use of short-distance and wireless communication technology (e.g., Wifi and Zigbee) are suggested to shorten the delay caused by subway operation incidents. Finally, the temporal transferability test results show that the developed log-logistic AFT model with random parameters is stable over time.

  10. Our sun. I. The standard model: Successes and failures

    SciTech Connect

    Sackmann, I.J.; Boothroyd, A.I.; Fowler, W.A. )

    1990-09-01

    The results of computing a number of standard solar models are reported. A presolar helium content of Y = 0.278 is obtained, and a Cl-37 capture rate of 7.7 SNUs, consistently several times the observed rate of 2.1 SNUs, is determined. Thus, the solar neutrino problem remains. The solar Z value is determined primarily by the observed Z/X ratio and is affected very little by differences in solar models. Even large changes in the low-temperature molecular opacities have no effect on Y, nor even on conditions at the base of the convective envelope. Large molecular opacities do cause a large increase in the mixing-length parameter alpha but do not cause the convective envelope to reach deeper. The temperature remains too low for lithium burning, and there is no surface lithium depletion; thus, the lithium problem of the standard solar model remains. 103 refs.

  11. Original mechanism of failure initiation revealed through modelling of naturally occurring microstructures

    NASA Astrophysics Data System (ADS)

    Gorbatikh, Larissa; Lomov, Stepan V.; Verpoest, Ignaas

    2010-05-01

    Motivated to reveal original mechanisms of failure resistance, we developed a material model that encompasses most reoccurring microstructural features of natural composites. The interesting result of the work is a notion that material failure is governed by the quality of interactions between hierarchical levels in the material microstructure. With intelligent use of the structure, these interactions can be tuned to create a powerful synergetic effect on the material failure behaviour. For example, while exploring different mechanisms of failure initiation in composites with bimodal size reinforcements (an indirect way to model two levels of hierarchy simultaneously) we found that failure initiation could be shifted from stress concentration sites of the higher level to the lower level. One could say that the material behaviour became insensitive to the presence of reinforcements on the higher level—a phenomenon that is counterintuitive to what is commonly known. The new mechanism of failure initiation could only be activated in composites with a highly controlled structural organization—in the studied case, reinforcements of the lower level needed to establish lamellar pathways between reinforcements of the higher level. These pathways lead to formation of an intriguing network-like microstructure. Intelligent communication between reinforcements in such a network created the necessary synergy to change the failure initiation mechanism in a discontinuous fashion. Another finding was that by establishing such a network, tensile stresses near dangerous stress concentration sites were locally transformed into compressive stresses. Resemblance of the revealed mechanism to phenomena on the nano-scale was also discussed. In the course of this work a new method was developed to investigate interactions between reinforcements and their collective input into effective and local properties of a composite. The reinforcement phase was modelled with the use of rigid

  12. Wide-area traffic: The failure of Poisson modeling

    SciTech Connect

    Paxson, V.; Floyd, S.

    1994-08-01

    Network arrivals are often modeled as Poisson processes for analytic simplicity, even though a number of traffic studies have shown that packet interarrivals are not exponentially distributed. The authors evaluate 21 wide-area traces, investigating a number of wide-area TCP arrival processes (session and connection arrivals, FTPDATA connection arrivals within FTP sessions, and TELNET packet arrivals) to determine the error introduced by modeling them using Poisson processes. The authors find that user-initiated TCP session arrivals, such as remote-login and file-transfer, are well-modeled as Poisson processes with fixed hourly rates, but that other connection arrivals deviate considerably from Poisson; that modeling TELNET packet interarrivals as exponential grievously underestimates the burstiness of TELNET traffic, but using the empirical Tcplib[DJCME92] interarrivals preserves burstiness over many time scales; and that FTPDATA connection arrivals within FTP sessions come bunched into ``connection bursts``, the largest of which are so large that they completely dominate FTPDATA traffic. Finally, they offer some preliminary results regarding how the findings relate to the possible self-similarity of wide-area traffic.

  13. Modeling of porous elastic viscoplastic material with tensile failure

    SciTech Connect

    Glenn, L A; Rubin, M; Vorobiev, O

    1998-11-01

    This work describes simple but comprehensive constitutive equations that model a number of physical phenomena exhibited by dry porous geological materials and metals. Moreover, formulas have been developed for robust numerical integration of the evolution equations at the element level that can be easily implemented into standard computer programs for dynamic response of materials.

  14. Evaluation of Progressive Failure Analysis and Modeling of Impact Damage in Composite Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Sanchez, Christopher M.

    2011-01-01

    NASA White Sands Test Facility (WSTF) is leading an evaluation effort in advanced destructive and nondestructive testing of composite pressure vessels and structures. WSTF is using progressive finite element analysis methods for test design and for confirmation of composite pressure vessel performance. Using composite finite element analysis models and failure theories tested in the World-Wide Failure Exercise, WSTF is able to estimate the static strength of composite pressure vessels. Additionally, test and evaluation on composites that have been impact damaged is in progress so that models can be developed to estimate damage tolerance and the degradation in static strength.

  15. THREE-DIMENSIONAL IGNITION AND GROWTH REACTIVE FLOW MODELING OF PRISM FAILURE TESTS ON PBX 9502

    SciTech Connect

    Garcia, M L; Tarver, C M

    2006-06-20

    The Ignition and Growth reactive flow model for shock initiation and detonation of solid explosives based on triaminotirnitrobenzene (TATB) is applied to three-dimensional detonation wave propagation. The most comprehensive set of three-dimensional detonation wave propagation data is that measured using the trapezoidal prism test. In this test, a PBX 9501 (95% HMX, 2.5% Estane, and 2.5% BDNPA/F) line detonator initiates a detonation wave along the trapezoidal face of a PBX 9502 (95% TATB and 5% Kel-F binder) prism. The failure thickness, which has been shown experimentally to be roughly half of the failure diameter of a long cylindrical charge, is measured after 50 mm of detonation wave propagation by impact with an aluminum witness plate. The effects of confinement impedance on the PBX 9502 failure thickness have been measured using air (unconfined), water, PMMA, magnesium, aluminum, lead, and copper placed in contact with the rectangular faces of the prism parallel to the direction of detonation propagation. These prism test results are modeled using the two-dimensional PBX 9502 Ignition and Growth model parameters determined by calculating failure diameter and tested on recent corner turning experiments. Good agreement between experimentally measured and calculated prism failure thicknesses for unconfined and confined PBX 9502 is reported.

  16. Load redistribution rules for progressive failure in shallow landslides: Threshold mechanical models

    NASA Astrophysics Data System (ADS)

    Fan, Linfeng; Lehmann, Peter; Or, Dani

    2017-01-01

    Rainfall-induced landslides are often preceded by progressive failures that culminate in abrupt mass release. Local failure progression is captured by a landslide hydro-mechanical triggering model that represents the soil mantle as interacting columns linked by tensile and compressive mechanical "bonds." Mechanical bonds may fail at a prescribed threshold leaving a modeling challenge of how to redistribute their load to neighboring intact soil columns. We employed an elastic spring-block model to analytically derive redistribution rules defined by the stiffness ratio of compressive to tensile bonds. These linear-elastic rules were generalized to real soil using measurable Young's modulus and Poisson's ratio. Results indicate that "local" failure characteristics of ductile-like soils (e.g., clay) are reproduced by low stiffness ratios, whereas "global" failure of brittle sandy soils corresponds to large stiffness ratios. Systematic analyses yield guidelines for selecting load redistribution rules for failure of geological materials and mass-movement phenomena represented by discrete threshold-mechanics.

  17. Cycle life test and failure model of nickel-hydrogen cells

    NASA Technical Reports Server (NTRS)

    Smithrick, J. J.

    1983-01-01

    Six ampere hour individual pressure vessel nickel hydrogen cells were charge/discharge cycled to failure. Failure as used here is defined to occur when the end of discharge voltage degraded to 0.9 volts. They were cycled under a low earth orbit cycle regime to a deep depth of discharge (80 percent of rated ampere hour capacity). Both cell designs were fabricated by the same manufacturer and represent current state of the art. A failure model was advanced which suggests both cell designs have inadequate volume tolerance characteristics. The limited existing data base at a deep depth of discharge (DOD) was expanded. Two cells of each design were cycled. One COMSAT cell failed at cycle 1712 and the other failed at cycle 1875. For the Air Force/Hughes cells, one cell failed at cycle 2250 and the other failed at cycle 2638. All cells, of both designs, failed due to low end of discharge voltage (0.9 volts). No cell failed due to electrical shorts. After cell failure, three different reconditioning tests (deep discharge, physical reorientation, and open circuit voltage stand) were conducted on all cells of each design. A fourth reconditioning test (electrolyte addition) was conducted on one cell of each design. In addition post cycle cell teardown and failure analysis were performed on the one cell of each design which did not have electrolyte added after failure.

  18. Cycle life test and failure model of nickel-hydrogen cells

    NASA Technical Reports Server (NTRS)

    Smithrick, J. J.

    1983-01-01

    Six ampere hour individual pressure vessel nickel hydrogen cells were charge/discharge cycled to failure. Failure as used here is defined to occur when the end of discharge voltage degraded to 0.9 volts. They were cycled under a low earth orbit cycle regime to a deep depth of discharge (80 percent of rated ampere hour capacity). Both cell designs were fabricated by the same manufacturer and represent current state of the art. A failure model was advanced which suggests both cell designs have inadequate volume tolerance characteristics. The limited existing data base at a deep depth of discharge (DOD) was expanded. Two cells of each design were cycled. One COMSAT cell failed at cycle 1712 and the other failed at cycle 1875. For the Air Force/Hughes cells, one cell failed at cycle 2250 and the other failed at cycle 2638. All cells, of both designs, failed due to low end of discharge voltage (0.9 volts). No cell failed due to electrical shorts. After cell failure, three different reconditioning tests (deep discharge, physical reorientation, and open circuit voltage stand) were conducted on all cells of each design. A fourth reconditioning test (electrolyte addition) was conducted on one cell of each design. In addition post cycle cell teardown and failure analysis were performed on the one cell of each design which did not have electrolyte added after failure. Previously announced in STAR as N83-25038

  19. Lack of cardiac nerve sprouting after intramyocardial transplantation of bone marrow-derived stem cells in a swine model of chronic ischemic myocardium.

    PubMed

    Liu, Yuan; Lai, Wing-Hon; Liao, Song-Yan; Siu, Chung-Wah; Yang, Yan-Zong; Tse, Hung-Fat

    2012-06-01

    Previous experimental studies suggested that mesenchymal stem cell transplantation causes cardiac nerve sprouting; however, whether bone marrow (BM)-derived mononuclear cells (MNC) and endothelial progenitor cells (EPC) can also lead to cardiac nerve sprouting and alter gap junction expression remains unclear. We investigated the effect of electroanatomical mapping-guided direct intramyocardial transplantation of BM-MNC (n = 8) and CD31+EPC (n = 8) compared with saline control (n = 8) on cardiac nerve sprouting and gap junction expression in a swine model of chronic ischemic myocardium. At 12 weeks after transplantation, the distribution and density of cardiac nerve sprouting were determined by staining of tyrosine hydroxylase (TH) and growth associated protein 43(GAP-43) and expression of connexin 43 in the targeted ischemic and remote normal myocardium. After 12 weeks, no animal developed sudden death after the transplantation. There were no significant differences in the number of cells with positive staining of TH and GAP-43 in the ischemic and normal myocardium between three groups. Furthermore, expression of connexin 43 was also similar in the ischemic and normal myocardia in each group of animals (P > 0.05). The results of this study demonstrated that intramyocardial BM-derived MNC or EPC transplantation in a large animal model of chronic myocardial ischemia was not associated with increased cardiac nerve sprouting over the ischemic myocardium.

  20. N-11C-Methyl-Dopamine PET Imaging of Sympathetic Nerve Injury in a Swine Model of Acute Myocardial Ischemia: A Comparison with 13N-Ammonia PET

    PubMed Central

    Zhou, Weina; Wang, Xiangcheng; He, Yulin; Nie, Yongzhen; Zhang, Guojian; Wang, Cheng; Wang, Chunmei; Wang, Xuemei

    2016-01-01

    Objective. Using a swine model of acute myocardial ischemia, we sought to validate N-11C-methyl-dopamine (11C-MDA) as an agent capable of imaging cardiac sympathetic nerve injury. Methods. Acute myocardial ischemia was surgically generated in Chinese minipigs. ECG and serum enzyme levels were used to detect the presence of myocardial ischemia. Paired 11C-MDA PET and 13N-ammonia PET scans were performed at baseline, 1 day, and 1, 3, and 6 months after surgery to relate cardiac sympathetic nerve injury to blood perfusion. Results. Seven survived the surgical procedure. The ECG-ST segment was depressed, and levels of the serum enzymes increased. Cardiac uptake of tracer was quantified as the defect volume. Both before and immediately after surgery, the images obtained with 11C-MDA and 13N-ammonia were similar. At 1 to 6 months after surgery, however, 11C-MDA postsurgical left ventricular myocardial defect volume was significantly greater compared to 13N-ammonia. Conclusions. In the Chinese minipig model of acute myocardial ischemia, the extent of the myocardial defect as visualized by 11C-MDA is much greater than would be suggested by blood perfusion images, and the recovery from myocardial sympathetic nerve injury is much slower than the restoration of blood perfusion. 11C-MDA PET may provide additional biological information during recovery from ischemic heart disease. PMID:27034950

  1. A visco-poroelastic damage model for modelling compaction and brittle failure of porous rocks

    NASA Astrophysics Data System (ADS)

    Jacquey, Antoine B.; Cacace, Mauro; Blöcher, Guido; Milsch, Harald; Scheck-Wenderoth, Magdalena

    2016-04-01

    Hydraulic stimulation of geothermal wells is often used to increase heat extraction from deep geothermal reservoirs. Initiation and propagation of fractures due to pore pressure build-up increase the effective permeability of the porous medium. Understanding the processes controlling the initiation of fractures, the evolution of their geometries and the hydro-mechanical impact on transport properties of the porous medium is therefore of great interest for geothermal energy production. In this contribution, we will present a thermodynamically consistent visco-poroelastic damage model which can deal with the multi-scale and multi-physics nature of the physical processes occurring during deformation of a porous rock. Deformation of a porous medium is crucially influenced by the changes in the effective stress. Considering a strain-formulated yield cap and the compaction-dilation transition, three different regimes can be identified: quasi-elastic deformation, cataclastic compaction with microcracking (damage accumulation) and macroscopic brittle failure with dilation. The governing equations for deformation, damage accumulation/healing and fluid flow have been implemented in a fully-coupled finite-element-method based framework (MOOSE). The MOOSE framework provides a powerful and flexible platform to solve multiphysics problems implicitly and in a tightly coupled manner on unstructured meshes which is of interest for such non-linear context. To validate and illustrate the model, simulations of the deformation behaviour of cylindrical porous Bentheimer sandstone samples under different confining pressures are compared to experiments. The first experiment under low confining pressure leads to shear failure, the second for high confining pressure leads to cataclastic compaction and the third one with intermediate confining pressure correspond to a transitional regime between the two firsts. Finally, we will demonstrate that this approach can also be used at the field

  2. Statistical analysis of bivariate failure time data with Marshall-Olkin Weibull models.

    PubMed

    Li, Yang; Sun, Jianguo; Song, Shuguang

    2012-06-01

    This paper discusses parametric analysis of bivariate failure time data, which often occur in medical studies among others. For this, as in the case of univariate failure time data, exponential and Weibull models are probably the most commonly used ones. However, it is surprising that there seem no general estimation procedures available for fitting the bivariate Weibull model to bivariate right-censored failure time data except some methods for special situations. We present and investigate two general but simple estimation procedures, one being a graphical approach and the other being a marginal approach, for the problem. An extensive simulation study is conducted to assess the performances of the proposed approaches and shows that they work well for practical situations. An illustrative example is provided.

  3. Advances in Constitutive and Failure Models for Sheet Forming Simulation

    NASA Astrophysics Data System (ADS)

    Yoon, Jeong Whan; Stoughton, Thomas B.

    2016-08-01

    Non-Associated Flow Rule (Non-AFR) can be used as a convenient way to account for anisotropic material response in metal deformation processes, making it possible for example, to eliminate the problem of the anomalous yielding in equibiaxial tension that is mistakenly attributed to limitations of the quadratic yield function, but may instead be attributed to the Associated Flow Rule (AFR). Seeing as in Non-AFR based models two separate functions can be adopted for yield and plastic potential, there is no constraint to which models are used to describe each of them. In this work, the flexible combination of two different yield criteria as yield function and plastic potential under Non-AFR is proposed and evaluated. FE simulations were carried so as to verify the accuracy of the material directionalities predicted using these constitutive material models. The stability conditions for non-associated flow connected with the prediction of yield point elongation are also reviewed. Anisotropic distortion hardening is further incorporated under non-associated flow. It has been found that anisotropic hardening makes the noticeable improvements for both earing and spring-back predictions. This presentation is followed by a discussion of the topic of the forming limit & necking, the evidence in favor of stress analysis, and the motivation for the development of a new type of forming limit diagram based on the polar effective plastic strain (PEPS) diagram. In order to connect necking to fracture in metals, the stress-based necking limit is combined with a stress- based fracture criterion in the principal stress, which provides an efficient method for the analysis of necking and fracture limits. The concept for the PEPS diagram is further developed to cover the path-independent PEPS fracture which is compatible with the stress-based fracture approach. Thus this fracture criterion can be utilized to describe the post-necking behavior and to cover nonlinear strain-path. Fracture

  4. Classical swine fever.

    PubMed

    Moennig, V; Becher, P; Beer, M

    2013-01-01

    Classical swine fever is a serious and economically important transboundary disease threatening pig production globally. The infection may occur in backyard pigs, feral pig populations and domestic pigs. Whereas there are proven control strategies for the latter pig population, control in backyard pigs with poor biosecurity settings or in wild boar populations of high density still poses a problem in some parts of the world. Laboratory diagnostic methods, efficacious vaccines and contingency plans are in place in most industrialised countries. So far modified live vaccines (MLV) are still the first choice for rapid and reliable immune protection. Since antibodies elicited by conventional MLV cannot be distinguished from antibodies after natural infection, considerable efforts are put into the development of a live marker vaccine accompanied by a serological test. Nevertheless, some remaining gaps with respect to the diagnosis of and vaccination against classical swine fever have been identified.

  5. Genotoxicity of swine effluents.

    PubMed

    Techio, V H; Stolberg, J; Kunz, A; Zanin, E; Perdomo, C C

    2011-01-01

    This study aimed at the investigation of genotoxic effects of swine effluents from different stages of a treatment system for swine wastes through bioassay of stamen hairs and micronuclei in Tradescantia (clone BNL 4430). No significant differences (p≥0.05) regarding the genic mutations were found in the bioassay of stamen hairs, independently of the effluent analysed. For the genotoxicity test with micronuclei, the plants exposed to raw wastes, to sludge, and to effluent of the biodigester have presented higher rates of chromosomal damages (micronuclei), with significant differences in relation to the control group and other effluent of the waste treatment system (p≤0.05). The association between the chemical parameters and the genotoxicity data have shown that the variables COD and TKN have presented significant correlation (p≤0.05) with the number of mutagenic events in the tetrads.

  6. Voltage-based Device Tracking in a 1.5 Tesla MRI during Imaging: Initial validation in swine models

    PubMed Central

    Schmidt, Ehud J; Tse, Zion TH; Reichlin, Tobias R; Michaud, Gregory F; Watkins, Ronald D; Butts-Pauly, Kim; Kwong, Raymond Y; Stevenson, William; Schweitzer, Jeffrey; Byrd, Israel; Dumoulin, Charles L

    2013-01-01

    Purpose Voltage-based device-tracking (VDT) systems are commonly used for tracking invasive devices in electrophysiological (EP) cardiac-arrhythmia therapy. During EP procedures, electro-anatomic-mapping (EAM) workstations provide guidance by integrating VDT location and intra-cardiac-ECG information with X-ray, CT, Ultrasound, and MR images. MR assists navigation, mapping and radio-frequency-ablation. Multi-modality interventions require multiple patient transfers between an MRI and the X-ray/ultrasound EP suite, increasing the likelihood of patient-motion and image mis-registration. An MRI-compatible VDT system may increase efficiency, since there is currently no single method to track devices both inside and outside the MRI scanner. Methods An MRI-compatible VDT system was constructed by modifying a commercial system. Hardware was added to reduce MRI gradient-ramp and radio-frequency-unblanking-pulse interference. VDT patches and cables were modified to reduce heating. Five swine cardiac VDT EAM-mapping interventions were performed, navigating inside and thereafter outside the MRI. Results Three-catheter VDT interventions were performed at >12 frames-per-second both inside and outside the MRI scanner with <3mm error. Catheters were followed on VDT- and MRI-derived maps. Simultaneous VDT and imaging was possible in repetition-time (TR) >32 msec sequences with <0.5mm errors, and <5% MRI SNR loss. At shorter TRs, only intra-cardiac-ECG was reliable. RF Heating was <1.5C°. Conclusion An MRI-compatible VDT system is feasible. PMID:23580479

  7. Do telemonitoring projects of heart failure fit the Chronic Care Model?

    PubMed Central

    Willemse, Evi; Adriaenssens, Jef; Dilles, Tinne; Remmen, Roy

    2014-01-01

    This study describes the characteristics of extramural and transmural telemonitoring projects on chronic heart failure in Belgium. It describes to what extent these telemonitoring projects coincide with the Chronic Care Model of Wagner. Background The Chronic Care Model describes essential components for high-quality health care. Telemonitoring can be used to optimise home care for chronic heart failure. It provides a potential prospective to change the current care organisation. Methods This qualitative study describes seven non-invasive home-care telemonitoring projects in patients with heart failure in Belgium. A qualitative design, including interviews and literature review, was used to describe the correspondence of these home-care telemonitoring projects with the dimensions of the Chronic Care Model. Results The projects were situated in primary and secondary health care. Their primary goal was to reduce the number of readmissions for chronic heart failure. None of these projects succeeded in a final implementation of telemonitoring in home care after the pilot phase. Not all the projects were initiated to accomplish all of the dimensions of the Chronic Care Model. A central role for the patient was sparse. Conclusion Limited financial resources hampered continuation after the pilot phase. Cooperation and coordination in telemonitoring appears to be major barriers but are, within primary care as well as between the lines of care, important links in follow-up. This discrepancy can be prohibitive for deployment of good chronic care. Chronic Care Model is recommended as basis for future. PMID:25114664

  8. Structural Nested Cumulative Failure Time Models to Estimate the Effects of Interventions

    PubMed Central

    Picciotto, Sally; Hernán, Miguel A.; Page, John H.; Young, Jessica G.; Robins, James M.

    2013-01-01

    In the presence of time-varying confounders affected by prior treatment, standard statistical methods for failure time analysis may be biased. Methods that correctly adjust for this type of covariate include the parametric g-formula, inverse probability weighted estimation of marginal structural Cox proportional hazards models, and g-estimation of structural nested accelerated failure time models. In this article, we propose a novel method to estimate the causal effect of a time-dependent treatment on failure in the presence of informative right-censoring and time-dependent confounders that may be affected by past treatment: g-estimation of structural nested cumulative failure time models (SNCFTMs). An SNCFTM considers the conditional effect of a final treatment at time m on the outcome at each later time k by modeling the ratio of two counterfactual cumulative risks at time k under treatment regimes that differ only at time m. Inverse probability weights are used to adjust for informative censoring. We also present a procedure that, under certain “no-interaction” conditions, uses the g-estimates of the model parameters to calculate unconditional cumulative risks under nondynamic (static) treatment regimes. The procedure is illustrated with an example using data from a longitudinal cohort study, in which the “treatments” are healthy behaviors and the outcome is coronary heart disease. PMID:24347749

  9. Data-Driven Risk Assessment from Small Scale Epidemics: Estimation and Model Choice for Spatio-Temporal Data with Application to a Classical Swine Fever Outbreak

    PubMed Central

    Gamado, Kokouvi; Marion, Glenn; Porphyre, Thibaud

    2017-01-01

    Livestock epidemics have the potential to give rise to significant economic, welfare, and social costs. Incursions of emerging and re-emerging pathogens may lead to small and repeated outbreaks. Analysis of the resulting data is statistically challenging but can inform disease preparedness reducing potential future losses. We present a framework for spatial risk assessment of disease incursions based on data from small localized historic outbreaks. We focus on between-farm spread of livestock pathogens and illustrate our methods by application to data on the small outbreak of Classical Swine Fever (CSF) that occurred in 2000 in East Anglia, UK. We apply models based on continuous time semi-Markov processes, using data-augmentation Markov Chain Monte Carlo techniques within a Bayesian framework to infer disease dynamics and detection from incompletely observed outbreaks. The spatial transmission kernel describing pathogen spread between farms, and the distribution of times between infection and detection, is estimated alongside unobserved exposure times. Our results demonstrate inference is reliable even for relatively small outbreaks when the data-generating model is known. However, associated risk assessments depend strongly on the form of the fitted transmission kernel. Therefore, for real applications, methods are needed to select the most appropriate model in light of the data. We assess standard Deviance Information Criteria (DIC) model selection tools and recently introduced latent residual methods of model assessment, in selecting the functional form of the spatial transmission kernel. These methods are applied to the CSF data, and tested in simulated scenarios which represent field data, but assume the data generation mechanism is known. Analysis of simulated scenarios shows that latent residual methods enable reliable selection of the transmission kernel even for small outbreaks whereas the DIC is less reliable. Moreover, compared with DIC, model choice

  10. Identification of Modeling Approaches To Support Common-Cause Failure Analysis

    SciTech Connect

    Korsah, Kofi; Wood, Richard Thomas

    2015-06-01

    Experience with applying current guidance and practices for common-cause failure (CCF) mitigation to digital instrumentation and control (I&C) systems has proven problematic, and the regulatory environment has been unpredictable. The impact of CCF vulnerability is to inhibit I&C modernization and, thereby, challenge the long-term sustainability of existing plants. For new plants and advanced reactor concepts, the issue of CCF vulnerability for highly integrated digital I&C systems imposes a design burden resulting in higher costs and increased complexity. The regulatory uncertainty regarding which mitigation strategies are acceptable (e.g., what diversity is needed and how much is sufficient) drives designers to adopt complicated, costly solutions devised for existing plants. The conditions that constrain the transition to digital I&C technology by the U.S. nuclear industry require crosscutting research to resolve uncertainty, demonstrate necessary characteristics, and establish an objective basis for qualification of digital technology for usage in Nuclear Power Plant (NPP) I&C applications. To fulfill this research need, Oak Ridge National Laboratory is conducting an investigation into mitigation of CCF vulnerability for nuclear-qualified applications. The outcome of this research is expected to contribute to a fundamentally sound, comprehensive technical basis for establishing the qualification of digital technology for nuclear power applications. This report documents the investigation of modeling approaches for representing failure of I&C systems. Failure models are used when there is a need to analyze how the probability of success (or failure) of a system depends on the success (or failure) of individual elements. If these failure models are extensible to represent CCF, then they can be employed to support analysis of CCF vulnerabilities and mitigation strategies. Specifically, the research findings documented in this report identify modeling approaches that

  11. Brain tissue oxygen tension and its response to physiological manipulations: influence of distance from injury site in a swine model of traumatic brain injury.

    PubMed

    Hawryluk, Gregory W J; Phan, Nicolas; Ferguson, Adam R; Morabito, Diane; Derugin, Nikita; Stewart, Campbell L; Knudson, M Margaret; Manley, Geoffrey; Rosenthal, Guy

    2016-11-01

    OBJECTIVE The optimal site for placement of tissue oxygen probes following traumatic brain injury (TBI) remains unresolved. The authors used a previously described swine model of focal TBI and studied brain tissue oxygen tension (PbtO2) at the sites of contusion, proximal and distal to contusion, and in the contralateral hemisphere to determine the effect of probe location on PbtO2 and to assess the effects of physiological interventions on PbtO2 at these different sites. METHODS A controlled cortical impact device was used to generate a focal lesion in the right frontal lobe in 12 anesthetized swine. PbtO2 was measured using Licox brain tissue oxygen probes placed at the site of contusion, in pericontusional tissue (proximal probe), in the right parietal region (distal probe), and in the contralateral hemisphere. PbtO2 was measured during normoxia, hyperoxia, hypoventilation, and hyperventilation. RESULTS Physiological interventions led to expected changes, including a large increase in partial pressure of oxygen in arterial blood with hyperoxia, increased intracranial pressure (ICP) with hypoventilation, and decreased ICP with hyperventilation. Importantly, PbtO2 decreased substantially with proximity to the focal injury (contusion and proximal probes), and this difference was maintained at different levels of fraction of inspired oxygen and partial pressure of carbon dioxide in arterial blood. In the distal and contralateral probes, hypoventilation and hyperventilation were associated with expected increased and decreased PbtO2 values, respectively. However, in the contusion and proximal probes, these effects were diminished, consistent with loss of cerebrovascular CO2 reactivity at and near the injury site. Similarly, hyperoxia led to the expected rise in PbtO2 only in the distal and contralateral probes, with little or no effect in the proximal and contusion probes, respectively. CONCLUSIONS PbtO2 measurements are strongly influenced by the distance from the

  12. An improved approach for flight readiness certification: Probabilistic models for flaw propagation and turbine blade failure. Volume 2: Software documentation

    NASA Technical Reports Server (NTRS)

    Moore, N. R.; Ebbeler, D. H.; Newlin, L. E.; Sutharshana, S.; Creager, M.

    1992-01-01

    An improved methodology for quantitatively evaluating failure risk of spaceflights systems to assess flight readiness and identify risk control measures is presented. This methodology, called Probabilistic Failure Assessment (PFA), combines operating experience from tests and flights with analytical modeling of failure phenomena to estimate failure risk. The PFA methodology is of particular value when information on which to base an assessment of failure risk, including test experience and knowledge of parameters used in analytical modeling, is expensive or difficult to acquire. The PFA methodology is a prescribed statistical structure in which analytical models that characterize failure phenomena are used conjointly with uncertainties about analysis parameters and/or modeling accuracy to estimate failure probability distributions for specific failure modes. These distributions can then be modified, by means of statistical procedures of the PFA methodology, to reflect any test or flight experience. State-of-the-art analytical models currently employed for design, failure prediction, or performance analysis are used in this methodology. The rationale for the statistical approach taken in the PFA methodology is discussed, the PFA methodology is described, and examples of its application to structural failure modes are presented. The engineering models and computer software used in fatigue crack growth and fatigue crack initiation applications are thoroughly documented.

  13. Experiments for Calibration and Validation of Plasticity and Failure Material Modeling: 6061-T651 Aluminum

    SciTech Connect

    McFadden, Sam X.; Korellis, John S.; Lee, Kenneth L.; Rogillio, Brendan R.; Hatch, Paul W.

    2008-03-01

    Experimental data for material plasticity and failure model calibration and validation were obtained from 6061-T651 aluminum, in the form of a 4-in. diameter extruded rod. Model calibration data were taken from smooth tension, notched tension, and shear tests. Model validation data were provided from experiments using thin-walled tube specimens subjected to path-dependent combinations of internal pressure, extension, and torsion.

  14. Comparison of compact bone failure under two different loading rates: experimental and modelling approaches.

    PubMed

    Pithioux, M; Subit, D; Chabrand, P

    2004-10-01

    Understanding the mechanical behaviour of bones up to failure is necessary for diagnosis and prevention of accident and trauma. As far as we know, no authors have yet studied the tensile behaviour of compact bone including failure under dynamic loadings (1 m/s). The originality of this study comes from not only the analysis of compact bone failure under dynamic loadings, the results of which are compared to those obtained under quasi-static loadings, but also the development of a statistical model. We developed a protocol using three different devices. Firstly, an X-ray scanner to analyse bone density, secondly, a common tensile device to perform quasi-static experiments, and thirdly, a special device based upon a hydraulic cylinder to perform dynamic tests. For all the tests, we used the same sample shape which took into account the brittleness of the compact bone. We first performed relaxation and hysteresis tests followed by tensile tests up to failure. Viscous and plastic effects were not relevant to the compact bone behaviour so its behaviour was considered elastic and brittle. The bovine compact bone was three to four times more brittle under a dynamic load than under a quasi-static one. Numerically, a statistical model, based upon the Weibull theory, is used to predict the failure stress in compact bone.

  15. Investigation of precipitate refinement in Mg alloys by an analytical composite failure model

    SciTech Connect

    Tabei, Ali; Li, Dongsheng; Lavender, Curt A.; Garmestani, Hamid

    2015-10-01

    An analytical model is developed to simulate precipitate refinement in second phase strengthened magnesium alloys. The model is developed based on determination of the stress fields inside elliptical precipitates embedded in a rate dependent inelastic matrix. The stress fields are utilized to determine the failure mode that governs the refinement behavior. Using an AZ31 Mg alloy as an example, the effects the applied load, aspect ratio and orientation of the particle is studied on the macroscopic failure of a single α-Mg17Al12 precipitate. Additionally, a temperature dependent version of the corresponding constitutive law is used to incorporate the effects of temperature. In plane strain compression, an extensional failure mode always fragments the precipitates. The critical strain rate at which the precipitates start to fail strongly depends on the orientation of the precipitate with respect to loading direction. The results show that the higher the aspect ratio is, the easier the precipitate fractures. Precipitate shape is another factor influencing the failure response. In contrast to elliptical precipitates with high aspect ratio, spherical precipitates are strongly resistant to sectioning. In pure shear loading, in addition to the extensional mode of precipitate failure, a shearing mode may get activated depending on orientation and aspect ratio of the precipitate. The effect of temperature in relation to strain rate was also verified for plane strain compression and pure shear loading cases.

  16. Mathematical modelling of blood-brain barrier failure and edema

    NASA Astrophysics Data System (ADS)

    Waters, Sarah; Lang, Georgina; Vella, Dominic; Goriely, Alain

    2015-11-01

    Injuries such as traumatic brain injury and stroke can result in increased blood-brain barrier permeability. This increase may lead to water accumulation in the brain tissue resulting in vasogenic edema. Although the initial injury may be localised, the resulting edema causes mechanical damage and compression of the vasculature beyond the original injury site. We employ a biphasic mixture model to investigate the consequences of blood-brain barrier permeability changes within a region of brain tissue and the onset of vasogenic edema. We find that such localised changes can indeed result in brain tissue swelling and that the type of damage that results (stress damage or strain damage) depends on the ability of the brain to clear edema fluid.

  17. 9 CFR 85.5 - Interstate movement of infected swine or exposed swine.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Interstate movement of infected swine or exposed swine. 85.5 Section 85.5 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... PRODUCTS PSEUDORABIES § 85.5 Interstate movement of infected swine or exposed swine. Infected swine...

  18. 9 CFR 85.5 - Interstate movement of infected swine or exposed swine.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Interstate movement of infected swine or exposed swine. 85.5 Section 85.5 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... PRODUCTS PSEUDORABIES § 85.5 Interstate movement of infected swine or exposed swine. Infected swine...

  19. 9 CFR 85.5 - Interstate movement of infected swine or exposed swine.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Interstate movement of infected swine or exposed swine. 85.5 Section 85.5 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... PRODUCTS PSEUDORABIES § 85.5 Interstate movement of infected swine or exposed swine. Infected swine...

  20. 9 CFR 85.5 - Interstate movement of infected swine or exposed swine.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Interstate movement of infected swine or exposed swine. 85.5 Section 85.5 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... PRODUCTS PSEUDORABIES § 85.5 Interstate movement of infected swine or exposed swine. Infected swine...

  1. 9 CFR 94.10 - Swine from regions where classical swine fever exists.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Swine from regions where classical swine fever exists. 94.10 Section 94.10 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... SWINE FEVER, CLASSICAL SWINE FEVER, SWINE VESICULAR DISEASE, AND BOVINE SPONGIFORM...

  2. 9 CFR 85.5 - Interstate movement of infected swine or exposed swine.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Interstate movement of infected swine or exposed swine. 85.5 Section 85.5 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... PRODUCTS PSEUDORABIES § 85.5 Interstate movement of infected swine or exposed swine. Infected swine...

  3. Swine Worker Precautions During Suspected Outbreaks of Influenza in Swine.

    PubMed

    Paccha, Blanca; Neira-Ramirez, Victor; Gibbs, Shawn; Torremorell, Montserrat; Rabinowitz, Peter M

    2016-05-01

    To assess the behavior and precautions that swine workers take during suspected influenza outbreaks in swine, six commercial swine farms in the Midwest U.S. region were visited when influenza outbreaks were suspected in herds during the fall/winter of 2012-2013. Use of personal protective equipment (PPE) and type of task performed by swine workers were recorded based on farm representative reports. Between one to two workers were working on the day of each visit and spent approximately 25 minutes performing work-related tasks that placed them in close contact with the swine. The most common tasks reported were walking the aisles (27%), handling pigs (21%), and handling equipment (21%). The most common PPE were boots (100%), heavy rubber gloves (75%), and dedicated nondisposable clothing (74%). Use of N95 respirators was reported at three farms. Hand hygiene practices were common in most of the farms, but reportedly performed for only 20% to 25% of tasks.

  4. Failure of climate regulation in a geophysiological model

    NASA Astrophysics Data System (ADS)

    Lovelock, James E.; Kump, Lee R.

    1994-06-01

    THERE has been much debate about how the Earth responds to changes in climate-specifically, how feedbacks involving the biota change with temperature. There is in particular an urgent need to understand the extent of coupling and feedback between plant growth, global temperature and enhanced atmospheric concentrations of greenhouse gases. Here we present a simple, but we hope qualitatively realistic, analysis of the effects of temperature change on the feedbacks induced by changes in surface distribution of marine algae and land plants. We assume that algae affect climate primarily through their emission of dimethyl sulphide1-8 (which may influence cloud albedo), and that land plants do so by fixation of atmospheric CO2 (refs 9-12). When we consider how the planetary area occupied by these two ecosystems varies with temperature, we find that a simple model based on these ideas exhibits three feedback regimes. In glacial conditions, both marine and terrestrial ecosystems provide a negative feedback. As the temperature rises to present-day values, algae lose their strong climate influence, but terrestrial ecosystems continue to regulate the climate. But if global mean temperatures rise above about 20 °C, both terrestrial and marine ecosystems are in positive feedback, amplifying any further increase of temperature. As the latter conditions have existed in the past, we propose that other climate-regulating mechanisms must operate in this warm regime.

  5. Evaluating the risk of water distribution system failure: A shared frailty model

    NASA Astrophysics Data System (ADS)

    Clark, Robert M.; Thurnau, Robert C.

    2011-12-01

    Condition assessment (CA) Modeling is drawing increasing interest as a technique that can assist in managing drinking water infrastructure. This paper develops a model based on the application of a Cox proportional hazard (PH)/shared frailty model and applies it to evaluating the risk of failure in drinking water networks using data from the Laramie Water Utility (located in Laramie, Wyoming, USA). Using the risk model a cost/ benefit analysis incorporating the inspection value method (IVM), is used to assist in making improved repair, replacement and rehabilitation decisions for selected drinking water distribution system pipes. A separate model is developed to predict failures in prestressed concrete cylinder pipe (PCCP). Various currently available inspection technologies are presented and discussed.

  6. Comparison of Hemostatic Durability between N-Butyl Cyanoacrylate and Gelatin Sponge Particles in Transcatheter Arterial Embolization for Acute Arterial Hemorrhage in a Coagulopathic Condition in a Swine Model

    SciTech Connect

    Yonemitsu, Takafumi; Kawai, Nobuyuki; Sato, Morio Sonomura, Tetsuo; Takasaka, Isao; Nakai, Motoki; Minamiguchi, Hiroki; Sahara, Shinya; Iwasaki, Yasuhiro; Naka, Toshio; Shinozaki, Masahiro

    2010-12-15

    This study was designed to compare the efficacy of transcatheter arterial embolization (TAE) with N-butyl cyanoacrylate (NBCA) or gelatin sponge particles (GSP) for acute arterial bleeding in a coagulopathic condition using a swine model. Four healthy swine were divided into two coagulopathic conditions: mild and severe. Five hemorrhages were created in each swine (10 hemorrhages per coagulopathy). Mild coagulopathy was achieved by bloodletting 10% of the total circulatory whole blood and preserving activated clotting time (ACT) less than 200 s (ACT < 200 s state); severe coagulopathy was achieved by bloodletting 30% and preserving ACT > 400 s (ACT > 400-second state). For each state, of ACT < 200 s or ACT > 400 s, TAE was conducted with GSP or NBCA to control five hemorrhages arising from artificially created renal and splenic injuries. Angiography immediately after TAE with GSP or NBCA showed complete occlusion in both coagulopathic conditions. In the ACT < 200-second state, follow-up angiography at 5-30 min after TAE with GSP or NBCA showed no evidence of recurrent hemorrhage. In the ACT > 400-second state, follow-up angiography showed recurrent hemorrhage in four (80%) of the five hemorrhages embolized with GSP and in one (20%) of the five hemorrhages embolized with NBCA. Microscopically, red thrombi were observed densely surrounding GSP in mild coagulopathy but were scarce in severe coagulopathy. In a condition with severe coagulopathy, TAE with NBCA was more effective in durability to cease active arterial bleeding than with GSP.

  7. Mycoplasma hyopneumoniae bacterins and porcine circovirus type 2 (PCV2) infection: induction of postweaning multisystemic wasting syndrome (PMWS) in the gnotobiotic swine model of PCV2-associated disease.

    PubMed

    Krakowka, Steven; Ellis, John; McNeilly, Francis; Waldner, Cheryl; Rings, D Michael; Allan, Gordon

    2007-07-01

    Groups (5 to 15 per group) of gnotobiotic swine were infected oronasally with porcine circovirus type 2 (PCV2) at 3 days of age and then given 1 of 6 different commercial Mycoplasma hyopneumoniae (M. hyopneumoniae) bacterins as either a single dose (7 d of age, 1 application products) or 2 doses (7 and 21 d of age, 2 application product). Control groups received PCV2 alone (n = 9) or were infected with PCV2 and immunized twice with keyhole limpet hemocyanin (KLH) emulsified in incomplete Freund's adjuvant (ICFA) (n = 7). Five of 7 (71%) PCV2-infected piglets immunized with KLH/ICFA developed mild or overt PMWS, whereas none of 9 piglets infected with PCV2 alone developed PMWS. Five of 12 (42%) piglets vaccinated with a commercial bacterin containing mineral oil adjuvant developed PMWS following vaccination. None of the PCV2-infected piglets in the other bacterin-vaccinated groups developed PMWS in this model of PCV2-associated disease. This difference in prevalence of PMWS in piglets given the mineral oil-adjuvanted M. hyopneumoniae bacterin and the other M. hyopneumoniae bacterin vaccination groups was statistically significant (P < 0.05).

  8. Liver Hypertrophy After Percutaneous Portal Vein Embolization: Comparison of N-Butyl-2-Cyanocrylate Versus Sodium Acrylate-Vinyl Alcohol Copolymer Particles in a Swine Model

    SciTech Connect

    Tsoumakidou, Georgia; Theocharis, Stamatis; Ptohis, Nikolaos Alexopoulou, Efthimia; Mantziaras, George; Kelekis, Nikolaos L. Brountzos, Elias N.

    2011-10-15

    Purpose: Percutaneous portal vein embolization (PPVE) induces hypertrophy of the future liver remnant before hepatic resection. The ideal embolic material has not yet been determined. We compared N-butyl-2-cyanocrylate (NBCA) with sodium acrylate-vinyl alcohol copolymer particles using a swine model. Materials and Methods: Twelve pigs underwent PPVE. Six pigs (group A) were embolized with NBCA, and 6 pigs (group B) were embolized with sodium acrylate-vinyl alcohol copolymer particles. Computed tomographic volumetry of the embolized lobe (EL) and the nonembolized lobe (NEL), along with liver function tests, was performed before and at 14 and 28 days after embolization. Tissue samples from both lobes were taken 14 and 28 days after PPVE. Results: NEL-volume and NEL-ratio increases were significantly higher in group A at 14 and 28 days after PPVE (78 and 52% and 91 and 66%, respectively) than in group B (32 and 12% and 28 and 10%, respectively) (p < 0.05). Percent change of the EL-volume was significantly higher for group A at 28 days after PPVE. No statistically significant difference was found between the groups regarding hepatocyte proliferation on the NEL and apoptosis on the EL at both time intervals. Conclusion: PPVE using NBCA is more efficient and causes more NEL hypertrophy than microspheres.

  9. Endoscopic ultrasound-assisted direct peritoneal visualization with a small-caliber scope: A proof of concept study in a swine model

    PubMed Central

    Suzuki, Rei; Bhutani, Manoop S.; Shin, Dongsuk; Irisawa, Atsushi; Fleming, Jason B.; Richards-Kortum, Rebecca; Ohira, Hiromasa

    2014-01-01

    Background: Laparoscopic and natural orifice transluminal endoscopic surgery techniques can diagnose peritoneal findings that suggest tumor cell dissemination. However, they have not been incorporated into routine practice, mainly owing to their complexity. To develop a minimally invasive endoscopic technique for the diagnosis of peritoneal findings, we conducted feasibility study using an acute swine model. Materials and Methods: This study involved six domestic pigs. Trans-gastric access to the peritoneal cavity was performed utilizing an endoscopic ultrasound fine needle aspiration (EUS-FNA) technique. After dilation of the needle hole with a biliary dilatation catheter and balloon, a small-caliber scope was inserted into the peritoneal cavity. Peritoneal images were obtained with the scope and a high-resolution microendoscope (HRME). Main outcome measurements were technical feasibility and time needed to access the peritoneal cavity. Results: Direct visualization of the peritoneum was successful in all six pigs and gained access to the gross appearance of the peritoneal cavity. HRME imaging with topical contrast agent also obtained reasonable quality images representing nuclei of the peritoneal mesothelium. Average operation time from the initiation of EUS-FNA to acquiring peritoneal images was 26.5 min (range 15-40 min). Autopsy found no damage to the adjacent organs, and stomach wall defects were tightly closed with hemostasis clips. Conclusion: EUS-assisted direct peritoneal visualization with small-caliber scope is technically feasible. HRME may assist in the diagnosis of findings on the peritoneum. PMID:25485270

  10. Magnetic Resonance Imaging of Acute Reperfused Myocardial Infarction: Intraindividual Comparison of ECIII-60 and Gd-DTPA in a Swine Model

    SciTech Connect

    Jin Jiyang; Teng Gaojun; Feng Yi; Wu Yanping; Jin Qindi; Wang Yu; Wang Zhen; Lu Qin; Jiang Yibo; Wang Shengqi; Chen Feng; Marchal, Guy; Ni Yicheng

    2007-04-15

    Purpose. To compare a necrosis-avid contrast agent (NACA) bis-Gd-DTPA-pamoic acid derivative (ECIII-60) after intracoronary delivery with an extracellular agent Gd-DTPA after intravenous injection on magnetic resonance imaging (MRI) in a swine model of acute reperfused myocardial infarction (MI). Methods. Eight pigs underwent 90 min of transcatheter coronary balloon occlusion and 60 min of reperfusion. After intravenous injection of Gd-DTPA at a dose of 0.2 mmol/kg, all pigs were scanned with T1-weighted MRI until the delayed enhancement of MI disappeared. Then they were intracoronarily infused with ECIII-60 at 0.0025 mmol/kg and imaged for 5 hr. Signal intensity, infarct-over-normal contrast ratio and relative infarct size were quantified, compared, and correlated with the results of postmortem MRI and triphenyltetrazolium chloride (TTC) histochemical staining. Results. A contrast ratio over 3.0 was induced by both Gd-DTPA and ECIII-60. However, while the delayed enhancement with Gd-DTPA virtually vanished in 1 hr, ECIII-60 at an 80x smaller dose depicted the MI accurately over 5 hr as proven by ex vivo MRI and TTC staining. Conclusion. Both Gd-DTPA and ECIII-60 strongly enhanced acute MI. Comparing with fading contrast in a narrow time window with intravenous Gd-DTPA, intracoronary ECIII-60 persistently demarcated the acute MI, indicating a potential method for postprocedural assessment of myocardial viability after coronary interventions.

  11. A Bayesian network approach for modeling local failure in lung cancer

    NASA Astrophysics Data System (ADS)

    Oh, Jung Hun; Craft, Jeffrey; Lozi, Rawan Al; Vaidya, Manushka; Meng, Yifan; Deasy, Joseph O.; Bradley, Jeffrey D.; El Naqa, Issam

    2011-03-01

    Locally advanced non-small cell lung cancer (NSCLC) patients suffer from a high local failure rate following radiotherapy. Despite many efforts to develop new dose-volume models for early detection of tumor local failure, there was no reported significant improvement in their application prospectively. Based on recent studies of biomarker proteins' role in hypoxia and inflammation in predicting tumor response to radiotherapy, we hypothesize that combining physical and biological factors with a suitable framework could improve the overall prediction. To test this hypothesis, we propose a graphical Bayesian network framework for predicting local failure in lung cancer. The proposed approach was tested using two different datasets of locally advanced NSCLC patients treated with radiotherapy. The first dataset was collected retrospectively, which comprises clinical and dosimetric variables only. The second dataset was collected prospectively in which in addition to clinical and dosimetric information, blood was drawn from the patients at various time points to extract candidate biomarkers as well. Our preliminary results show that the proposed method can be used as an efficient method to develop predictive models of local failure in these patients and to interpret relationships among the different variables in the models. We also demonstrate the potential use of heterogeneous physical and biological variables to improve the model prediction. With the first dataset, we achieved better performance compared with competing Bayesian-based classifiers. With the second dataset, the combined model had a slightly higher performance compared to individual physical and biological models, with the biological variables making the largest contribution. Our preliminary results highlight the potential of the proposed integrated approach for predicting post-radiotherapy local failure in NSCLC patients.

  12. Higher Dimensional Clayton–Oakes Models for Multivariate Failure Time Data

    PubMed Central

    Prentice, R. L.

    2016-01-01

    Summary The Clayton–Oakes bivariate failure time model is extended to dimensions m > 2 in a manner that allows unspecified marginal survivor functions for all dimensions less than m. Special cases that allow unspecified marginal survivor functions of dimension q with q < m, while making some provisions for dependencies of dimension greater than q, are also described. PMID:27738350

  13. Assessment of compressive failure process of cortical bone materials using damage-based model.

    PubMed

    Ng, Theng Pin; R Koloor, S S; Djuansjah, J R P; Abdul Kadir, M R

    2017-02-01

    The main failure factors of cortical bone are aging or osteoporosis, accident and high energy trauma or physiological activities. However, the mechanism of damage evolution coupled with yield criterion is considered as one of the unclear subjects in failure analysis of cortical bone materials. Therefore, this study attempts to assess the structural response and progressive failure process of cortical bone using a brittle damaged plasticity model. For this reason, several compressive tests are performed on cortical bone specimens made of bovine femur, in order to obtain the structural response and mechanical properties of the material. Complementary finite element (FE) model of the sample and test is prepared to simulate the elastic-to-damage behavior of the cortical bone using the brittle damaged plasticity model. The FE model is validated in a comparative method using the predicted and measured structural response as load-compressive displacement through simulation and experiment. FE results indicated that the compressive damage initiated and propagated at central region where maximum equivalent plastic strain is computed, which coincided with the degradation of structural compressive stiffness followed by a vast amount of strain energy dissipation. The parameter of compressive damage rate, which is a function dependent on damage parameter and the plastic strain is examined for different rates. Results show that considering a similar rate to the initial slope of the damage parameter in the experiment would give a better sense for prediction of compressive failure.

  14. Continuum Damage Mechanics Models for the Analysis of Progressive Failure in Open-Hole Tension Laminates

    NASA Technical Reports Server (NTRS)

    Song, Kyonchan; Li, Yingyong; Rose, Cheryl A.

    2011-01-01

    The performance of a state-of-the-art continuum damage mechanics model for interlaminar damage, coupled with a cohesive zone model for delamination is examined for failure prediction of quasi-isotropic open-hole tension laminates. Limitations of continuum representations of intra-ply damage and the effect of mesh orientation on the analysis predictions are discussed. It is shown that accurate prediction of matrix crack paths and stress redistribution after cracking requires a mesh aligned with the fiber orientation. Based on these results, an aligned mesh is proposed for analysis of the open-hole tension specimens consisting of different meshes within the individual plies, such that the element edges are aligned with the ply fiber direction. The modeling approach is assessed by comparison of analysis predictions to experimental data for specimen configurations in which failure is dominated by complex interactions between matrix cracks and delaminations. It is shown that the different failure mechanisms observed in the tests are well predicted. In addition, the modeling approach is demonstrated to predict proper trends in the effect of scaling on strength and failure mechanisms of quasi-isotropic open-hole tension laminates.

  15. Complete mitochondrial genome sequence of the heart failure model of cardiomyopathic Syrian hamster (Mesocricetus auratus).

    PubMed

    Hu, Bo; Liu, Dong-Xing; Zhang, Yu-Qing; Song, Jian-Tao; Ji, Xian-Fei; Hou, Zhi-Qiang; Zhang, Zhen-Hai

    2016-05-01

    In this study we sequenced the complete mitochondrial genome sequencing of a heart failure model of cardiomyopathic Syrian hamster (Mesocricetus auratus) for the first time. The total length of the mitogenome was 16,267 bp. It harbored 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes and 1 non-coding control region.

  16. Vertical modelling: Analysis of competing risks data with missing causes of failure.

    PubMed

    Nicolaie, M A; van Houwelingen, H C; Putter, H

    2015-12-01

    We propose vertical modelling as a natural approach to the problem of analysis of competing risks data when failure types are missing for some individuals. Under a natural missing-at-random assumption for these missing failure types, we use the observed data likelihood to estimate its parameters and show that the all-cause hazard and the relative hazards appearing in vertical modelling are indeed key quantities of this likelihood. This fact has practical implications in that it suggests vertical modelling as a simple and attractive method of analysis in competing risks with missing causes of failure; all individuals are used in estimating the all-cause hazard and only those with non-missing cause of failure for relative hazards. The relative hazards also appear in a multiple imputation approach to the same problem proposed by Lu and Tsiatis and in the EM algorithm. We compare the vertical modelling approach with the method of Goetghebeur and Ryan for a breast cancer data set, highlighting the different aspects they contribute to the data analysis.

  17. Application of the health belief model in promotion of self-care in heart failure patients.

    PubMed

    Baghianimoghadam, Mohammad Hosein; Shogafard, Golamreza; Sanati, Hamid Reza; Baghianimoghadam, Behnam; Mazloomy, Seyed Saeed; Askarshahi, Mohsen

    2013-01-01

    Heart failure (HF) is a condition due to a problem with the structure or function of the heart impairs its ability to supply sufficient blood flow to meet the body's needs. In developing countries, around 2% of adults suffer from heart failure, but in people over the age of 65, this rate increases to 6-10%. In Iran, around 3.3% of adults suffer from heart failure. The Health Belief Model (HBM) is one of the most widely used models in public health theoretical framework. This was a cohort experimental study, in which education as intervention factor was presented to case group. 180 Heart failure patients were randomly selected from patients who were referred to the Shahid Rajaee center of Heart Research in Tehran and allocated to two groups (90 patients in the case group and 90 in the control group). HBM was used to compare health behaviors. The questionnaire included 69 questions. All data were collected before and 2 months after intervention. About 38% of participants don't know what, the heart failure is and 43% don't know that using the salt is not suitable for them. More than 40% of participants didn't weigh any time their selves. There was significant differences between the mean grades score of variables (perceived susceptibility, perceived threat, knowledge, Perceived benefits, Perceived severity, self-efficacy Perceived barriers, cues to action, self- behavior) in the case and control groups after intervention that was not significant before it. Based on our study and also many other studies, HBM has the potential to be used as a tool to establish educational programs for individuals and communities. Therefore, this model can be used effectively to prevent different diseases and their complications including heart failure.

  18. Porcine model characterizing various parameters assessing the outcome after acetaminophen intoxication induced acute liver failure

    PubMed Central

    Thiel, Karolin; Klingert, Wilfried; Klingert, Kathrin; Morgalla, Matthias H; Schuhmann, Martin U; Leckie, Pamela; Sharifi, Yalda; Davies, Nathan A; Jalan, Rajiv; Peter, Andreas; Grasshoff, Christian; Königsrainer, Alfred; Schenk, Martin; Thiel, Christian

    2017-01-01

    AIM To investigate the changes of hemodynamic and laboratory parameters during the course of acute liver failure following acetaminophen overdose. METHODS Eight pigs underwent a midline laparotomy following jejunal catheter placement for further acetaminophen intoxication and positioning of a portal vein Doppler flow-probe. Acute liver failure was realized by intrajejunal acetaminophen administration in six animals, two animals were sham operated. All animals were invasively monitored and received standardized intensive care support throughout the study. Portal blood flow, hemodynamic and ventilation parameters were continuously recorded. Laboratory parameters were analysed every eight hours. Liver biopsies were sampled every 24 h following intoxication and upon autopsy. RESULTS Acute liver failure (ALF) occurred after 28 ± 5 h resulted in multiple organ failure and death despite maximal support after further 21 ± 1 h (study end). Portal blood flow (baseline 1100 ± 156 mL/min) increased to a maximum flow of 1873 ± 175 mL/min at manifestation of ALF, which was significantly elevated (P < 0.01). Immediately after peaking, portal flow declined rapidly to 283 ± 135 mL/min at study end. Thrombocyte values (baseline 307 × 103/µL ± 34 × 103/µL) of intoxicated animals declined slowly to values of 145 × 103/µL ± 46 × 103/µL when liver failure occurred. Subsequent appearance of severe thrombocytopenia in liver failure resulted in values of 11 × 103/µL ± 3 × 103/µL preceding fatality within few hours which was significant (P > 0.01). CONCLUSION Declining portal blood flow and subsequent severe thrombocytopenia after acetaminophen intoxication precede fatality in a porcine acute liver failure model. PMID:28321158

  19. Outcomes for patients with congestive heart failure in a nursing case management model.

    PubMed

    Morrison, R S; Beckworth, V

    1998-01-01

    Congestive heart failure is a leading cause of hospital admissions, costing an estimated $7 billion in 1990. Hospital-based nursing case management has been used to reduce costs of care while maintaining quality of care. This study describes the outcomes for 50 patients with congestive heart failure in a hospital-based nursing care management model, providing general outcomes, physiologic status, physical functioning, health knowledge, and family caregiver status. The number of medications was the only predictor of length of stay using regression analysis.

  20. Blood-banking techniques for plateletpheresis in swine.

    PubMed

    Sondeen, Jill L; Prince, Malcolm D; Polykratis, Irene A; Hernandez, Orlando; Torres-Mendoza, Jaime; De Guzman, Rodolfo; Aden, James K; Dubick, Michael A

    2014-05-01

    During the past several years, trauma resuscitation in human patients has evolved from decreased use of crystalloids to increased use of blood products. Of high interest is the role of platelets in trauma resuscitation. Because conducting prehos- pital resuscitation in human trauma patients is very difficult, swine are often the animal model of choice for such studies because their coagulation and hemodynamic systems are similar to those in humans. However, consistent production of sufficient swine platelets for such studies has not previously been achieved. We developed a method for producing swine platelets by using standard human techniques and equipment. We assessed pH, pO2, pCO2, lactate, thromboelastography, and platelet aggregation over 5 d of storage to determine whether the swine platelet product met the American Association of Blood Banks (AABB) standards for transfusion. Swine platelets met AABB standards at 24 h but not at later time points. In addition, we fluorescently labeled nonautologous platelets and then measured their percentage recovery over 5 h (the time used in subsequent experimental studies) when transfused into a recipient pig. We showed that 80% of the platelets stored for 24 h remained in the circulation and increased the recipient pigs' thromboelastographic responses, indicating that the platelets were viable and active. Therefore, swine platelets stored for 24 h by using standard human products met the AABB criteria and were functional.

  1. Experiments and modeling of ballistic penetration using an energy failure criterion

    NASA Astrophysics Data System (ADS)

    Dolinski, M.; Rittel, D.

    2015-09-01

    One of the most intricate problems in terminal ballistics is the physics underlying penetration and perforation. Several penetration modes are well identified, such as petalling, plugging, spall failure and fragmentation (Sedgwick, 1968). In most cases, the final target failure will combine those modes. Some of the failure modes can be due to brittle material behavior, but penetration of ductile targets by blunt projectiles, involving plugging in particular, is caused by excessive localized plasticity, with emphasis on adiabatic shear banding (ASB). Among the theories regarding the onset of ASB, new evidence was recently brought by Rittel et al. (2006), according to whom shear bands initiate as a result of dynamic recrystallization (DRX), a local softening mechanism driven by the stored energy of cold work. As such, ASB formation results from microstructural transformations, rather than from thermal softening. In our previous work (Dolinski et al., 2010), a failure criterion based on plastic strain energy density was presented and applied to model four different classical examples of dynamic failure involving ASB formation. According to this criterion, a material point starts to fail when the total plastic strain energy density reaches a critical value. Thereafter, the strength of the element decreases gradually to zero to mimic the actual material mechanical behavior. The goal of this paper is to present a new combined experimental-numerical study of ballistic penetration and perforation, using the above-mentioned failure criterion. Careful experiments are carried out using a single combination of AISI 4340 FSP projectiles and 25[mm] thick RHA steel plates, while the impact velocity, and hence the imparted damage, are systematically varied. We show that our failure model, which includes only one adjustable parameter in this present work, can faithfully reproduce each of the experiments without any further adjustment. Moreover, it is shown that the most common

  2. Experiments and modeling of ballistic penetration using an energy failure criterion

    NASA Astrophysics Data System (ADS)

    Dolinski, M.; Rittel, D.

    2015-10-01

    One of the most intricate problems in terminal ballistics is the physics underlying penetration and perforation. Several penetration modes are well identified, such as petalling, plugging, spall failure and fragmentation (Sedgwick, 1968). In most cases, the final target failure will combine those modes. Some of the failure modes can be due to brittle material behavior, but penetration of ductile targets by blunt projectiles, involving plugging in particular, is caused by excessive localized plasticity, with emphasis on adiabatic shear banding (ASB). Among the theories regarding the onset of ASB, new evidence was recently brought by Rittel et al. (2006), according to whom shear bands initiate as a result of dynamic recrystallization (DRX), a local softening mechanism driven by the stored energy of cold work. As such, ASB formation results from microstructural transformations, rather than from thermal softening. In our previous work (Dolinski et al., 2010), a failure criterion based on plastic strain energy density was presented and applied to model four different classical examples of dynamic failure involving ASB formation. According to this criterion, a material point starts to fail when the total plastic strain energy density reaches a critical value. Thereafter, the strength of the element decreases gradually to zero to mimic the actual material mechanical behavior. The goal of this paper is to present a new combined experimental-numerical study of ballistic penetration and perforation, using the above-mentioned failure criterion. Careful experiments are carried out using a single combination of AISI 4340 FSP projectiles and 25[mm] thick RHA steel plates, while the impact velocity, and hence the imparted damage, are systematically varied. We show that our failure model, which includes only one adjustable parameter in this present work, can faithfully reproduce each of the experiments without any further adjustment. Moreover, it is shown that the most common

  3. Handling Qualities of Model Reference Adaptive Controllers with Varying Complexity for Pitch-Roll Coupled Failures

    NASA Technical Reports Server (NTRS)

    Schaefer, Jacob; Hanson, Curt; Johnson, Marcus A.; Nguyen, Nhan

    2011-01-01

    Three model reference adaptive controllers (MRAC) with varying levels of complexity were evaluated on a high performance jet aircraft and compared along with a baseline nonlinear dynamic inversion controller. The handling qualities and performance of the controllers were examined during failure conditions that induce coupling between the pitch and roll axes. Results from flight tests showed with a roll to pitch input coupling failure, the handling qualities went from Level 2 with the baseline controller to Level 1 with the most complex MRAC tested. A failure scenario with the left stabilator frozen also showed improvement with the MRAC. Improvement in performance and handling qualities was generally seen as complexity was incrementally added; however, added complexity usually corresponds to increased verification and validation effort required for certification. The tradeoff between complexity and performance is thus important to a controls system designer when implementing an adaptive controller on an aircraft. This paper investigates this relation through flight testing of several controllers of vary complexity.

  4. Modeling and Characterization of Dynamic Failure of Soda-lime Glass Under High Speed Impact

    SciTech Connect

    Liu, Wenning N.; Sun, Xin; Chen, Weinong W.; Templeton, Douglas W.

    2012-05-27

    In this paper, the impact-induced dynamic failure of a soda-lime glass block is studied using an integrated experimental/analytical approach. The Split Hopkinson Pressure Bar (SHPB) technique is used to conduct dynamic failure test of soda-lime glass first. The damage growth patterns and stress histories are reported for various glass specimen designs. Making use of a continuum damage mechanics (CDM)-based constitutive model, the initial failure and subsequent stiffness reduction of glass are simulated and investigated. Explicit finite element analyses are used to simulate the glass specimen impact event. A maximum shear stress-based damage evolution law is used in describing the glass damage process under combined compression/shear loading. The impact test results are used to quantify the critical shear stress for the soda-lime glass under examination.

  5. Modeling and Characterization of Dynamic Failure of Glasses Under High Speed Impact

    SciTech Connect

    Liu, Wenning N.; Sun, Xin

    2011-08-23

    : In this chapter, the impact-induced dynamic failure of a glass block is studied using an integrated experimental/analytical approach. Both soda-lime and borosilicate glass materials are investigated. The Split Hopkinson Pressure Bar (SHPB) technique is used to conduct dynamic failure test of soda-lime glass first. The damage growth patterns and stress histories are reported for various glass specimen designs. Making use of a continuum damage mechanics (CDM)-based constitutive model, the initial failure and subsequent stiffness reduction of glass are simulated and investigated. Explicit finite element analyses are used to simulate the glass specimen impact event. A maximum shear stress-based damage evolution law is used in describing the glass damage process under combined compression/shear loading. The impact test results are used to quantify the critical shear stress for the soda-lime glass under examination.

  6. Phospholamban Ablation Using CRISPR/Cas9 System Improves Mortality in a Murine Heart Failure Model

    PubMed Central

    Kaneko, Manami; Hashikami, Kentarou; Yamamoto, Satoshi; Matsumoto, Hirokazu; Nishimoto, Tomoyuki

    2016-01-01

    Sarcoplasmic reticulum Ca2+-ATPase 2a (SERCA2a) and its inhibitory protein called phospholamban (PLN) are pivotal for Ca2+ handling in cardiomyocyte and are known that their expression level and activity were changed in the heart failure patients. To examine whether PLN inhibition can improve survival rate as well as cardiac function in heart failure, we performed PLN ablation in calsequestrin overexpressing (CSQ-Tg) mice, a severe heart failure model, using clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (Cas) system. According this method, generation rate of PLN wild type mice (PLN copy >0.95) and PLN homozygous knockout (KO) mice (PLN copy <0.05) were 39.1% and 10.5%, respectively. While CSQ overexpression causes severe heart failure symptoms and premature death, a significant ameliorating effect on survival rate was observed in PLN homozygous KO/CSQ-Tg mice compared to PLN wild type/CSQ-Tg mice (median survival days are 55 and 50 days, respectively). Measurement of cardiac function with cardiac catheterization at the age of 5 weeks revealed that PLN ablation improved cardiac function in CSQ-Tg mice without affecting heart rate and blood pressure. Furthermore, increases in atrial and lung weight, an index of congestion, were significantly inhibited by PLN ablation. These results suggest that PLN deletion would be a promising approach to improve both mortality and cardiac function in the heart failure. PMID:27992596

  7. Estimating distributions with increasing failure rate in an imperfect repair model.

    PubMed

    Kvam, Paul H; Singh, Harshinder; Whitaker, Lyn R

    2002-03-01

    A failed system is repaired minimally if after failure, it is restored to the working condition of an identical system of the same age. We extend the nonparametric maximum likelihood estimator (MLE) of a system's lifetime distribution function to test units that are known to have an increasing failure rate. Such items comprise a significant portion of working components in industry. The order-restricted MLE is shown to be consistent. Similar results hold for the Brown-Proschan imperfect repair model, which dictates that a failed component is repaired perfectly with some unknown probability, and is otherwise repaired minimally. The estimators derived are motivated and illustrated by failure data in the nuclear industry. Failure times for groups of emergency diesel generators and motor-driven pumps are analyzed using the order-restricted methods. The order-restricted estimators are consistent and show distinct differences from the ordinary MLEs. Simulation results suggest significant improvement in reliability estimation is available in many cases when component failure data exhibit the IFR property.

  8. Proportional and scale change models to project failures of mechanical components with applications to space station

    NASA Technical Reports Server (NTRS)

    Taneja, Vidya S.

    1996-01-01

    In this paper we develop the mathematical theory of proportional and scale change models to perform reliability analysis. The results obtained will be applied for the Reaction Control System (RCS) thruster valves on an orbiter. With the advent of extended EVA's associated with PROX OPS (ISSA & MIR), and docking, the loss of a thruster valve now takes on an expanded safety significance. Previous studies assume a homogeneous population of components with each component having the same failure rate. However, as various components experience different stresses and are exposed to different environments, their failure rates change with time. In this paper we model the reliability of a thruster valves by treating these valves as a censored repairable system. The model for each valve will take the form of a nonhomogeneous process with the intensity function that is either treated as a proportional hazard model, or a scale change random effects hazard model. Each component has an associated z, an independent realization of the random variable Z from a distribution G(z). This unobserved quantity z can be used to describe heterogeneity systematically. For various models methods for estimating the model parameters using censored data will be developed. Available field data (from previously flown flights) is from non-renewable systems. The estimated failure rate using such data will need to be modified for renewable systems such as thruster valve.

  9. Avionics equipment failure prediction based on genetic programming and grey model

    NASA Astrophysics Data System (ADS)

    Deng, Xiujian; Luo, Qiang; Zhao, Yiyang; Feng, Qi

    2017-01-01

    Avionics equipment failure prediction by conventional GM (Grey Model) may yield large forecasting errors. Combining GM (1, 1) model with genetic programming algorithm, a kind of GP-GM (1, 1) forecast model was established to minimize such errors. Forecasting sequence was calculated by means of GM (1, 1) model, then genetic programming algorithm was used to modify them further, and the degradation trend prediction of characteristic parameters of avionics equipment was realized. The validity of GP-GM (1, 1) prediction model was testified by tracking and forecasting the experiment data of avionics equipment in real environment.

  10. An evidential reasoning extension to quantitative model-based failure diagnosis

    NASA Technical Reports Server (NTRS)

    Gertler, Janos J.; Anderson, Kenneth C.

    1992-01-01

    The detection and diagnosis of failures in physical systems characterized by continuous-time operation are studied. A quantitative diagnostic methodology has been developed that utilizes the mathematical model of the physical system. On the basis of the latter, diagnostic models are derived each of which comprises a set of orthogonal parity equations. To improve the robustness of the algorithm, several models may be used in parallel, providing potentially incomplete and/or conflicting inferences. Dempster's rule of combination is used to integrate evidence from the different models. The basic probability measures are assigned utilizing quantitative information extracted from the mathematical model and from online computation performed therewith.

  11. Tsunamis Triggered by Submarine Landslides in the NE Atlantic: Evidences of Mass Failures and Numerical Modeling

    NASA Astrophysics Data System (ADS)

    Omira, R.; Ramalho, I.; Baptista, M. A.; Miranda, J. M. A.; Batista, L.; Terrinha, P.

    2014-12-01

    Tsunamis caused by submarine mass failures constitute a widely recognized source of natural hazard. However, in the NE Atlantic the tsunami hazard posed by landslides remains poorly studied. In this study, we attempt to contribute to a better understanding of the tsunami hazard of landslides origin. We investigate the tsunami hazard posed by deepwater submarine landslide failures in the Gorringe Bank (GB) area, NE Atlantic. This investigation requires detailed marine geological data and a robust numerical model to simulate both the mass failure flow and the subsequent tsunami. The analysis of both swath-bathymetric data and the multichannel seismic profiles revealed evidences of the presence of at least three large deepwater mass failures in the GB area of possible tsunamigenic potential. It also allows defining the geomorphologic characteristics of the identified submarine landslides, which include the erosional area (dimensions, scarps) and the depositional area (sediments extent, volume). Some depositional volumes reach ~80km3. To simulate the flow of the mudslide failure and the wave induced by the seafloor motion we employ a multi-layers viscous shallow-water (VSW) model. The lower layer represents the slide assumed to be a viscous-incompressible fluid, and characterized by sediments density, and kinematic viscosity. It is bounded by the upper layer consisting of seawater assumed to be inviscid and incompressible. We solve the VSW equations in a finite-difference scheme considering a "two-way" coupling approach. The results are presented in terms of: i) evidences of submarine mass failures in the area of GB; ii) simulations of seafloor motion due to the occurrence slides failures; ii) simulations of tsunami generation induced by the submarine landslide flow; and iii) simulations of tsunami propagation and coastal impact. Results show that, using the VSW model, we are able to reliably reproduce the sediment deposit induced by slide failures. In some cases, the

  12. 9 CFR 94.10 - Swine from regions where classical swine fever exists.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... PRODUCTS RINDERPEST, FOOT-AND-MOUTH DISEASE, EXOTIC NEWCASTLE DISEASE, AFRICAN SWINE FEVER, CLASSICAL SWINE FEVER, SWINE VESICULAR DISEASE, AND BOVINE SPONGIFORM ENCEPHALOPATHY: PROHIBITED AND RESTRICTED..., Nayarit, Quintana Roo, Sinaloa, Sonora, and Yucatan; New Zealand; Norway; and Trust Territory of...

  13. Subject specific finite element modeling of periprosthetic femoral fracture using element deactivation to simulate bone failure.

    PubMed

    Miles, Brad; Kolos, Elizabeth; Walter, William L; Appleyard, Richard; Shi, Angela; Li, Qing; Ruys, Andrew J

    2015-06-01

    Subject-specific finite element (FE) modeling methodology could predict peri-prosthetic femoral fracture (PFF) for cementless hip arthoplasty in the early postoperative period. This study develops methodology for subject-specific finite element modeling by using the element deactivation technique to simulate bone failure and validate with experimental testing, thereby predicting peri-prosthetic femoral fracture in the early postoperative period. Material assignments for biphasic and triphasic models were undertaken. Failure modeling with the element deactivation feature available in ABAQUS 6.9 was used to simulate a crack initiation and propagation in the bony tissue based upon a threshold of fracture strain. The crack mode for the biphasic models was very similar to the experimental testing crack mode, with a similar shape and path of the crack. The fracture load is sensitive to the friction coefficient at the implant-bony interface. The development of a novel technique to simulate bone failure by element deactivation of subject-specific finite element models could aid prediction of fracture load in addition to fracture risk characterization for PFF.

  14. High fat feeding promotes obesity and renal inflammation and protects against post cardiopulmonary bypass acute kidney injury in swine

    PubMed Central

    2013-01-01

    Introduction Obesity confers a survival advantage in the critically ill and in patients undergoing cardiac surgery. We explored whether an obesogenic high fat diet could confer protection against post cardiopulmonary bypass (CPB) acute kidney injury (AKI) in a swine model. Methods In this study, 28 anaesthetised adult female Landrace White swine (55 to 70 kg) were allocated into a 4 group design to either 2.5 hours of CPB or Sham operation with or without pre-procedural high fat (HF) feeding containing 15% lard, 1.5% cholesterol and 1% cholic acid for 12-weeks (Groups: Sham, CPB, CPB + HF and Sham + HF). Our primary endpoint was creatinine clearance measured at 1.5 and 24 hours post intervention. This is a validated index of the glomerular filtration rate (GFR) in swine and an endpoint used in our clinical studies. Secondary endpoints included measures of systemic and renal inflammation, endothelial homeostasis, tubular injury and dysfunction, and inflammatory cell signalling. Differences between groups were calculated using analysis of variance with adjustment for baseline differences for repeated measures. Results CPB in pigs fed a normal chow diet resulted in AKI. This was characterised by reductions in GFR sustained for up to 24 hours post injury relative to Sham operated pigs fed a normal diet; mean difference 50.2 ml/min (95% CI 5.9 to 94.4). Post CPB AKI was also characterised by renal inflammation, parallel activation of both pro-inflammatory (NF-kB, iNOS) and pro-survival pathways (pAkt, p70s6k, HIF-1α) and apoptosis. Pigs fed a 12-week high fat diet developed obesity and hyperlipidaemia. This was associated with increased redox sensitive pro-inflammatory and anti-apoptotic signalling, and tubular epithelial cell proliferation. High fat feeding also protected swine against post CPB AKI; mean difference in creatinine clearance CPB - CPB + HF −65.3 ml/min (95% CI −106.9 to −23.7), by preserving endothelial homeostasis and function

  15. Parameterization of grounding-line cliff failure in an Antarctic ice sheet model

    NASA Astrophysics Data System (ADS)

    Pollard, David; DeConto, Robert

    2014-05-01

    Two mechanisms have recently been added to a 3-D ice-sheet model that can produce drastic retreat into East Antarctic sub-glacial basins during past warm periods, as implied by (albeit uncertain) geologic evidence. The two mechanisms, (1) structural failure of large tidewater cliffs, and (2) enhanced ice-shelf calving due to meltwater draining into crevasses, present challenges in their parameterization within coarse-grid models. Here we describe details and choices in the parameterization of structural failure at deep grounding lines, its incorporation into the large-scale dynamical equations, and the sensitivity of model results to these choices. In addition, a parameterization of melt-enhanced calving is described, along with a simple representation of the clogging effects of ice melange in narrow seaways, and their effects on Antarctic simulations.

  16. Fatigue failure in the cement mantle of a simplified acetabular replacement model

    PubMed Central

    Zant, Nikolaus P.; Wong, Charles K.Y.; Tong, Jie

    2007-01-01

    Although the role of fatigue failure in aseptic loosening of cemented total hip replacements has been extensively studied in femoral components, studies of fatigue failure in cement mantle of acetabular replacements have yet to be reported, despite that the long-term failure rate in the latter is about three times that of femoral components. Part of the reason may be that a complex pelvic bone structure does not land itself readily for a 2D representation as that of a femur. In this work, a simple multilayer model has been developed to reproduce the stress distributions in the cement mantle of an acetabular replacement from a plane strain finite element pelvic bone model. The experimental multilayer model was subjected to cyclic loading up to peak hip contact force during normal walking. Radial fatigue cracks were observed in the vicinity of the maximum tangential and compressive stresses, as predicted by the FE models. Typical fatigue striations were also observed on the fracture surfaces post cyclic testing. The results were examined in the context of retrieval studies, 3D FE analysis and in vitro experimental results using full-sized hemi-pelvic bone models. PMID:19330048

  17. Failure of Tube Models to Predict the Linear Rheology of Star/Linear Blends

    NASA Astrophysics Data System (ADS)

    Hall, Ryan; Desai, Priyanka; Kang, Beomgoo; Katzarova, Maria; Huang, Qifan; Lee, Sanghoon; Chang, Taihyun; Venerus, David; Mays, Jimmy; Schieber, Jay; Larson, Ronald

    We compare predictions of two of the most advanced versions of the tube model, namely the Hierarchical model by Wang et al. (J. Rheol. 54:223, 2010) and the BOB (branch-on-branch) model by Das et al. (J. Rheol. 50:207-234, 2006), against linear viscoelastic data on blends of monodisperse star and monodisperse linear polybutadiene polymers. The star was carefully synthesized/characterized by temperature gradient interaction chromatography, and rheological data in the high frequency region were obtained through time-temperature superposition. We found massive failures of both the Hierarchical and BOB models to predict the terminal relaxation behavior of the star/linear blends, despite their success in predicting the rheology of the pure star and pure linear. This failure occurred regardless of the choices made concerning constraint release, such as assuming arm retraction in fat or skinny tubes, or allowing for disentanglement relaxation to cut off the constraint release Rouse process at long times. The failures call into question whether constraint release can be described as a combination of constraint release Rouse processes and dynamic tube dilation within a canonical tube model of entanglement interactions.

  18. Cap plasticity models and compactive and dilatant pre-failure deformation

    SciTech Connect

    FOSSUM,ARLO F.; FREDRICH,JOANNE T.

    2000-02-17

    At low mean stresses, porous geomaterials fail by shear localization, and at higher mean stresses, they undergo strain-hardening behavior. Cap plasticity models attempt to model this behavior using a pressure-dependent shear yield and/or shear limit-state envelope with a hardening or hardening/softening elliptical end cap to define pore collapse. While these traditional models describe compactive yield and ultimate shear failure, difficulties arise when the behavior involves a transition from compactive to dilatant deformation that occurs before the shear failure or limit-state shear stress is reached. In this work, a continuous surface cap plasticity model is used to predict compactive and dilatant pre-failure deformation. During loading the stress point can pass freely through the critical state point separating compactive from dilatant deformation. The predicted volumetric strain goes from compactive to dilatant without the use of a non-associated flow rule. The new model is stable in that Drucker's stability postulates are satisfied. The study has applications to several geosystems of current engineering interest (oil and gas reservoirs, nuclear waste repositories, buried targets, and depleted reservoirs for possible use for subsurface sequestration of greenhouse gases).

  19. SEMIPARAMETRIC TRANSFORMATION MODELS WITH RANDOM EFFECTS FOR CLUSTERED FAILURE TIME DATA

    PubMed Central

    Zeng, Donglin; Lin, D. Y.; Lin, Xihong

    2009-01-01

    We propose a general class of semiparametric transformation models with random effects to formulate the effects of possibly time-dependent covariates on clustered or correlated failure times. This class encompasses all commonly used transformation models, including proportional hazards and proportional odds models, and it accommodates a variety of random-effects distributions, particularly Gaussian distributions. We show that the nonparametric maximum likelihood estimators of the model parameters are consistent, asymptotically normal and asymptotically efficient. We develop the corresponding likelihood-based inference procedures. Simulation studies demonstrate that the proposed methods perform well in practical situations. An illustration with a well-known diabetic retinopathy study is provided. PMID:19809573

  20. Record breaking bursts in a discrete element model of compressive failure

    NASA Astrophysics Data System (ADS)

    Kun, F.; Pál, G.; Raischel, F.; Lennartz-Sassinek, S.; Main, I. G.

    2015-12-01

    We investigate the statistics of records in the time series of crackling bursts emerging during the compressive failure of porous materials. Bursts of local breaking events are generated by computer simulations of the uniaxial compression of cylindrical samples in a discrete element model. We show that the number of records grows as a decelerating power law of the number of events followed by an acceleration immediately prior to failure. The size of records has a power law distribution with an exponent significantly smaller than the one of the complete burst size distribution. The lifetime of records proved to be also power law distributed with a relatively low exponent. Analyzing the behavior of average quantities of records we show the existence of a characteristic record rank k* which separates two regimes of the time evolution of the fracture process: the beginning of the failure process is characterized by the slow-down of record breaking due to the effect of disorder. Then record breaking accelerates as macroscopic failure is approached when spatial and temporal correlations dominate. Scaling analysis revealed that the size distribution of records of different ranks has a universal form independent of the record rank. Sub-sequences of bursts enclosed by consecutive records are characterized by a power law size distribution with an exponent which decreases as failure is approached. Our analysis revealed that records have a strong effect on the structure of the surrounding time series: high rank records are preceded by bursts of increasing size and waiting time between consecutive events and they are followed by a relaxation process. In principle the results could be used to improve forecasting of catastrophic failure events, if they can be observed reliably in a single experiment in real time.

  1. Earthquake and failure forecasting in real-time: A Forecasting Model Testing Centre

    NASA Astrophysics Data System (ADS)

    Filgueira, Rosa; Atkinson, Malcolm; Bell, Andrew; Main, Ian; Boon, Steven; Meredith, Philip

    2013-04-01

    Across Europe there are a large number of rock deformation laboratories, each of which runs many experiments. Similarly there are a large number of theoretical rock physicists who develop constitutive and computational models both for rock deformation and changes in geophysical properties. Here we consider how to open up opportunities for sharing experimental data in a way that is integrated with multiple hypothesis testing. We present a prototype for a new forecasting model testing centre based on e-infrastructures for capturing and sharing data and models to accelerate the Rock Physicist (RP) research. This proposal is triggered by our work on data assimilation in the NERC EFFORT (Earthquake and Failure Forecasting in Real Time) project, using data provided by the NERC CREEP 2 experimental project as a test case. EFFORT is a multi-disciplinary collaboration between Geoscientists, Rock Physicists and Computer Scientist. Brittle failure of the crust is likely to play a key role in controlling the timing of a range of geophysical hazards, such as volcanic eruptions, yet the predictability of brittle failure is unknown. Our aim is to provide a facility for developing and testing models to forecast brittle failure in experimental and natural data. Model testing is performed in real-time, verifiably prospective mode, in order to avoid selection biases that are possible in retrospective analyses. The project will ultimately quantify the predictability of brittle failure, and how this predictability scales from simple, controlled laboratory conditions to the complex, uncontrolled real world. Experimental data are collected from controlled laboratory experiments which includes data from the UCL Laboratory and from Creep2 project which will undertake experiments in a deep-sea laboratory. We illustrate the properties of the prototype testing centre by streaming and analysing realistically noisy synthetic data, as an aid to generating and improving testing methodologies in

  2. Modeling the effect of heat fluxes on ammonia and nitrous oxide emissions from an anaerobic swine waste treatment lagoon using artificial neural network

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding factors that affect ammonia and nitrous emissions from anaerobic swine waste treatment lagoons or any animal waste receptacles is a necessary first step in deploying potential remediation options. In this study, we examined the various meteorological factors (i.e., air temperatures, s...

  3. Intraosseous Hydroxocobalamin in the Treatment of Acute, Severe Cyanide Induced Cardiotoxicity in a Swine (Sus Scrofa) Model - An Alternate Administration Route for Chemical Mass Casualties

    DTIC Science & Technology

    2012-04-05

    methods – LICOX (PbO2), near infrared spectrophotometry (NIRS), and microdialysis. We will use three devices to assess neurologic function after...antidotal treatment. These measures are near infrared spectroscopy, brain oxygen tension, and brain microdialysis. Hypothesis We hypothesize...cerebral near infrared spectrometry (NIRS) oxygenation, and inflammatory markers. Methods 24 swine (48-52 kg) were intubated, anesthetized, and

  4. Modeling the attenuation and failure of action potentials in the dendrites of hippocampal neurons.

    PubMed Central

    Migliore, M

    1996-01-01

    We modeled two different mechanisms, a shunting conductance and a slow sodium inactivation, to test whether they could modulate the active propagation of a train of action potentials in a dendritic tree. Computer simulations, using a compartmental model of a pyramidal neuron, suggest that each of these two mechanisms could account for the activity-dependent attenuation and failure of the action potentials in the dendrites during the train. Each mechanism is shown to be in good qualitative agreement with experimental findings on somatic or dendritic stimulation and on the effects of hyperpolarization. The conditions under which branch point failures can be observed, and a few experimentally testable predictions, are presented and discussed. PMID:8913580

  5. A simple nonlocal damage model for predicting failure of notched laminates

    NASA Technical Reports Server (NTRS)

    Kennedy, T. C.; Nahan, M. F.

    1995-01-01

    The ability to predict failure loads in notched composite laminates is a requirement in a variety of structural design circumstances. A complicating factor is the development of a zone of damaged material around the notch tip. The objective of this study was to develop a computational technique that simulates progressive damage growth around a notch in a manner that allows the prediction of failure over a wide range of notch sizes. This was accomplished through the use of a relatively simple, nonlocal damage model that incorporates strain-softening. This model was implemented in a two-dimensional finite element program. Calculations were performed for two different laminates with various notch sizes under tensile loading, and the calculations were found to correlate well with experimental results.

  6. Critical points and transitions in an electric power transmission model for cascading failure blackouts.

    PubMed

    Carreras, B. A.; Lynch, V. E.; Dobson, I.; Newman, D. E.

    2002-12-01

    Cascading failures in large-scale electric power transmission systems are an important cause of blackouts. Analysis of North American blackout data has revealed power law (algebraic) tails in the blackout size probability distribution which suggests a dynamical origin. With this observation as motivation, we examine cascading failure in a simplified transmission system model as load power demand is increased. The model represents generators, loads, the transmission line network, and the operating limits on these components. Two types of critical points are identified and are characterized by transmission line flow limits and generator capability limits, respectively. Results are obtained for tree networks of a regular form and a more realistic 118-node network. It is found that operation near critical points can produce power law tails in the blackout size probability distribution similar to those observed. The complex nature of the solution space due to the interaction of the two critical points is examined.(c) 2002 American Institute of Physics.

  7. A model of school problems, academic failure, alcohol initiation, and the relationship to adult heroin injection.

    PubMed

    Trenz, Rebecca C; Harrell, Paul; Scherer, Michael; Mancha, Brent E; Latimer, William W

    2012-08-01

    The current study uses structural equation modeling to investigate factors associated with alcohol initiation and injection heroin use. Baseline data from the NEURO-HIV Epidemiologic Study in Baltimore, Maryland, were used. Participants were 404 injection heroin users (M(age) = 32.72) with a history of regular injection in their lifetime. Latent variables were created for self-reported school problems and academic failure. The final model indicated that greater school problems were associated with earlier alcohol initiation (ß = -0.22, p < .001) and earlier alcohol initiation was associated with greater frequency of recent heroin use (ß = -0.12, p < .05). Academic failure was directly related to greater frequency of recent heroin injection (ß = 0.15, p < .01). The results expand research investigating the relationship between adolescent behavior and illicit drug use in adulthood.

  8. A Closed Network Queue Model of Underground Coal Mining Production, Failure, and Repair

    NASA Technical Reports Server (NTRS)

    Lohman, G. M.

    1978-01-01

    Underground coal mining system production, failures, and repair cycles were mathematically modeled as a closed network of two queues in series. The model was designed to better understand the technological constraints on availability of current underground mining systems, and to develop guidelines for estimating the availability of advanced mining systems and their associated needs for spares as well as production and maintenance personnel. It was found that: mine performance is theoretically limited by the maintainability ratio, significant gains in availability appear possible by means of small improvements in the time between failures the number of crews and sections should be properly balanced for any given maintainability ratio, and main haulage systems closest to the mine mouth require the most attention to reliability.

  9. A Micromechanics Based Constitutive Model For Brittle Failure at High Strain Rates

    NASA Astrophysics Data System (ADS)

    Bhat, H. S.; Rosakis, A.; Sammis, C. G.

    2011-12-01

    The micromechanical damage mechanics formulated by Ashby and Sammis [1] and generalized by Desh- pande and Evans [2] has been extended to allow for a more generalized stress state and to incorporate an ex- perimentally motivated new crack growth (damage evo- lution) law that is valid over a wide range of loading rates. This law is sensitive to both the crack tip stress field and its time derivative. Incorporating this feature produces strain-rate sensitivity in the constitutive re- sponse. The model is also experimentally verified by predicting the failure strength of Dionysus-Pentelicon marble over strain rates ranging from ˜ 10-6 to 103 s-1. Model parameters determined from from quasi-static experiments were used to predict the failure strength at higher loading rates. Agreement with experimental results was excellent.

  10. Coronary Microembolization with Normal Epicardial Coronary Arteries and No Visible Infarcts on Nitrobluetetrazolium Chloride-Stained Specimens: Evaluation with Cardiac Magnetic Resonance Imaging in a Swine Model

    PubMed Central

    Jin, Hang; Yun, Hong; Ma, Jianying; Chen, Zhangwei; Chang, Shufu

    2016-01-01

    Objective To assess magnetic resonance imaging (MRI) features of coronary microembolization in a swine model induced by small-sized microemboli, which may cause microinfarcts invisible to the naked eye. Materials and Methods Eleven pigs underwent intracoronary injection of small-sized microspheres (42 µm) and catheter coronary angiography was obtained before and after microembolization. Cardiac MRI and measurement of cardiac troponin T (cTnT) were performed at baseline, 6 hours, and 1 week after microembolization. Postmortem evaluation was performed after completion of the imaging studies. Results Coronary angiography pre- and post-microembolization revealed normal epicardial coronary arteries. Systolic wall thickening of the microembolized regions decreased significantly from 42.6 ± 2.0% at baseline to 20.3 ± 2.3% at 6 hours and 31.5 ± 2.1% at 1 week after coronary microembolization (p < 0.001 for both). First-pass perfusion defect was visualized at 6 hours but the extent was largely decreased at 1 week. Delayed contrast enhancement MRI (DE-MRI) demonstrated hyperenhancement within the target area at 6 hours but not at 1 week. The microinfarcts on gross specimen stained with nitrobluetetrazolium chloride were invisible to the naked eye and only detectable microscopically. Increased cTnT was observed at 6 hours and 1 week after microembolization. Conclusion Coronary microembolization induced by a certain load of small-sized microemboli may result in microinfarcts invisible to the naked eye with normal epicardial coronary arteries. MRI features of myocardial impairment secondary to such microembolization include the decline in left ventricular function and myocardial perfusion at cine and first-pass perfusion imaging, and transient hyperenhancement at DE-MRI. PMID:26798220

  11. Biological effect on drug distribution and vascular healing via paclitaxel‐coated balloon technology in drug eluting stent restenosis swine model

    PubMed Central

    Li, Yan; Tellez, Armando; Rousselle, Serge D.; Dillon, Krista N.; Garza, Javier A.; Barry, Chris

    2015-01-01

    Objectives To evaluate the biological effect of a paclitaxel‐coated balloon (PCB) technology on vascular drug distribution and healing in drug eluting stent restenosis (DES‐ISR) swine model. Background The mechanism of action and healing response via PCB technology in DES‐ISR is not completely understood. Methods A total of 27 bare metal stents were implanted in coronary arteries and 30 days later the in‐stent restenosis was treated with PCB. Treated segments were harvested at 1 hr, 14 days and 30 days post treatment for the pharmacokinetic analysis. In addition, 24 DES were implanted in coronary arteries for 30 days, then all DES‐ISRs were treated with either PCB (n = 12) or uncoated balloon (n = 12). At day 60, vessels were harvested for histology following angiography and optical coherence tomography (OCT). Results The paclitaxel level in neointimal tissue was about 18 times higher (P = 0.0004) at 1 hr C max, and retained about five times higher (P = 0.008) at day 60 than that in vessel wall. A homogenous distribution of paclitaxel in ISR was demonstrated by using fluorescently labeled paclitaxel. Notably, in DES‐ISR, both termination OCT and quantitative coronary angioplasty showed a significant neointimal reduction and less late lumen loss (P = 0.05 and P = 0.03, respectively) post PCB versus post uncoated balloon. The PES‐ISR + PCB group displayed higher levels of peri‐strut inflammation and fibrin scores compared to the ‐limus DES‐ISR + PCB group. Conclusions In ISR, paclitaxel is primarily deposited in neointimal tissue and effectively retained over time following PCB use. Despite the presence of metallic struts, a uniform distribution was characterized. PCB demonstrated an equivalent biological effect in DES‐ISR without significantly increasing inflammation. © 2015 Wiley Periodicals, Inc. PMID:26613810

  12. Temporary Arterial Embolization of Liver Parenchyma with Degradable Starch Microspheres (EmboCept{sup ®}S) in a Swine Model

    SciTech Connect

    Pieper, Claus C. Meyer, Carsten; Vollmar, Brigitte; Hauenstein, Karlheinz; Schild, Hans H.; Wilhelm, Kai E.

    2015-04-15

    BackgroundThis study aimed to evaluate the embolic properties, time to reperfusion, and histologic changes in temporary embolization of liver tissue with degradable starch microspheres (DSM) in a swine model.MethodsIn four adult minipigs, DSMs were injected into the right or left hepatic artery on the lobar level until complete stasis of the blood flow was detectable angiographically. The time required to complete angiographically determined reperfusion was noted. The animals were killed 3 h after complete reperfusion, and samples were taken from the liver. Histologic examinations of the embolized liver parenchyma and untreated tissue were performed.ResultsHepatic arterial embolization using DSMs was technically successful in all cases, with complete blood flow stasis shown by control angiography. A single vial of DSMs (450 mg/7.5 ml) was sufficient to embolize a whole liver lobe in all cases. Angiography showed complete reconstitution of hepatic arterial perfusion after a mean time to reperfusion of 32 ± 6.1 min (range, 26–39 min). Hematoxylin and eosin staining showed no histologically detectable differences between untreated tissue and parenchyma embolized with DSMs except for mild sinusoidal congestion in one case. Indirect in situ DNA nick end labeling staining (TUNEL) showed only single positive hepatocytes, indicating apoptosis.ConclusionTemporary embolization of the hepatic artery using DSMs is feasible with complete reperfusion after 30 min in pigs. Even after complete arterial blood flow stasis, no extensive tissue damage to the embolized liver parenchyma was observed at histologic examinations in this short-term study.

  13. Modelling of Safety Instrumented Systems by using Bernoulli trials: towards the notion of odds on for SIS failures analysis

    NASA Astrophysics Data System (ADS)

    Cauffriez, Laurent

    2017-01-01

    This paper deals with the modeling of a random failures process of a Safety Instrumented System (SIS). It aims to identify the expected number of failures for a SIS during its lifecycle. Indeed, the fact that the SIS is a system being tested periodically gives the idea to apply Bernoulli trials to characterize the random failure process of a SIS and thus to verify if the PFD (Probability of Failing Dangerously) experimentally obtained agrees with the theoretical one. Moreover, the notion of "odds on" found in Bernoulli theory allows engineers and scientists determining easily the ratio between “outcomes with success: failure of SIS” and “outcomes with unsuccess: no failure of SIS” and to confirm that SIS failures occur sporadically. A Stochastic P-temporised Petri net is proposed and serves as a reference model for describing the failure process of a 1oo1 SIS architecture. Simulations of this stochastic Petri net demonstrate that, during its lifecycle, the SIS is rarely in a state in which it cannot perform its mission. Experimental results are compared to Bernoulli trials in order to validate the powerfulness of Bernoulli trials for the modeling of the failures process of a SIS. The determination of the expected number of failures for a SIS during its lifecycle opens interesting research perspectives for engineers and scientists by completing the notion of PFD.

  14. Decentralized Adaptive Control of Systems with Uncertain Interconnections, Plant-Model Mismatch and Actuator Failures

    NASA Technical Reports Server (NTRS)

    Patre, Parag; Joshi, Suresh M.

    2011-01-01

    Decentralized adaptive control is considered for systems consisting of multiple interconnected subsystems. It is assumed that each subsystem s parameters are uncertain and the interconnection parameters are not known. In addition, mismatch can exist between each subsystem and its reference model. A strictly decentralized adaptive control scheme is developed, wherein each subsystem has access only to its own state but has the knowledge of all reference model states. The mismatch is estimated online for each subsystem and the mismatch estimates are used to adaptively modify the corresponding reference models. The adaptive control scheme is extended to the case with actuator failures in addition to mismatch.

  15. A novel distributed model of the heart under normal and congestive heart failure conditions.

    PubMed

    Ravanshadi, Samin; Jahed, Mehran

    2013-04-01

    Conventional models of cardiovascular system frequently lack required detail and focus primarily on the overall relationship between pressure, flow and volume. This study proposes a localized and regional model of the cardiovascular system. It utilizes noninvasive blood flow and pressure seed data and temporal cardiac muscle regional activity to predict the operation of the heart under normal and congestive heart failure conditions. The analysis considers specific regions of the heart, namely, base, mid and apex of left ventricle. The proposed method of parameter estimation for hydraulic electric analogy model is recursive least squares algorithm. Based on simulation results and comparison to clinical data, effect of congestive heart failure in the heart is quantified. Accumulated results for simulated ejection fraction percentage of the apex, mid and base regions of the left ventricle in congestive heart failure condition were 39 ± 6, 36 ± 9 and 38 ± 8, respectively. These results are shown to satisfactorily match those found through clinical measurements. The proposed analytical method can in effect be utilized as a preclinical and predictive tool for high-risk heart patients and candidates for heart transplant, assistive device and total artificial heart.

  16. Micromechanics Based Multiscale Modeling of the Inelastic Response and Failure of Complex Architecture Composites

    NASA Astrophysics Data System (ADS)

    Liu, Kuang

    Advanced composites are being widely used in aerospace applications due to their high stiffness, strength and energy absorption capabilities. However, the assurance of structural reliability is a critical issue because a damage event will compromise the integrity of composite structures and lead to ultimate failure. In this dissertation a novel homogenization based multiscale modeling framework using semi-analytical micromechanics is presented to simulate the response of textile composites. The novelty of this approach lies in the three scale homogenization/localization framework bridging between the constituent (micro), the fiber tow scale (meso), weave scale (macro), and the global response. The multiscale framework, named Multiscale Generalized Method of Cells (MSGMC), continuously bridges between the micro to the global scale as opposed to approaches that are top-down and bottom-up. This framework is fully generalized and capable of modeling several different weave and braids without reformulation. Particular emphasis in this dissertation is placed on modeling the nonlinearity and failure of both polymer matrix and ceramic matrix composites. Results are presented for the cases of plain, twill, satin, and triaxially braided composites. Inelastic, failure, strain rate and damage effects are included at the microscale and propagated to the global scale. MSGMC was successfully used to predict the in-plane material response plain and five harness satin woven polymer composites, triaxially braided polymer composite and both the in-plane and out-of-plane response of silicon carbide ceramic matrix composites.

  17. Assessment of Three Finite Element Approaches for Modeling the Ballistic Impact Failure of Metal Plates

    NASA Astrophysics Data System (ADS)

    Mansur, Ali; Nganbe, Michel

    2015-03-01

    The ballistic impact was numerically modeled for AISI 450 steel struck by a 17.3 g ogive nose WC-Co projectile using Abaqus/Explicit. The model was validated using experimental results and data for different projectiles and metal targets. The Abaqus ductile-shear, local principal strain to fracture, and absorbed strain energy at failure criteria were investigated. Due to the highly dynamic nature of ballistic impacts, the absorbed strain energy approach posed serious challenges in estimating the effective deformation volume and yielded the largest critical plate thicknesses for through-thickness penetration (failure). In contrast, the principal strain criterion yielded the lowest critical thicknesses and provided the best agreement with experimental ballistic test data with errors between 0 and 30%. This better accuracy was due to early failure definition when the very first mesh at the target back side reached the strain to fracture, which compensated for the overall model overestimation. The ductile-shear criterion yielded intermediate results between those of the two comparative approaches. In contrast to the ductile-shear criterion, the principal strain criterion requires only basic data readily available for practically all materials. Therefore, it is a viable alternative for an initial assessment of the ballistic performance and pre-screening of a large number of new candidate materials as well as for supporting the development of novel armor systems.

  18. Comparison of Topical Hemostatic Agents in a Swine Model of Extremity Arterial Hemorrhage: BloodSTOP iX Battle Matrix vs. QuikClot Combat Gauze

    PubMed Central

    Li, Huixi; Wang, Lin; Alwaal, Amjad; Lee, Yung-Chin; Reed-Maldonado, Amanda; Spangler, Taylor A.; Banie, Lia; O’Hara, Reginald B.; Lin, Guiting

    2016-01-01

    BloodSTOP iX Battle Matrix (BM) and QuikClot Combat Gauze (CG) have both been used to treat traumatic bleeding. The purpose of this study was to examine the efficacy and initial safety of both products in a swine extremity arterial hemorrhage model, which mimics combat injury. Swine (37.13 ± 0.56 kg, NBM = 11, NCG = 9) were anesthetized and splenectomized. We then isolated the femoral arteries and performed a 6 mm arteriotomy. After 45 s of free bleeding, either BM or CG was applied. Fluid resuscitation was provided to maintain a mean arterial pressure of 65 mmHg. Animals were observed for three hours or until death. Fluoroscopic angiography and wound stability challenge tests were performed on survivors. Tissue samples were collected for histologic examination. Stable hemostasis was achieved in 11/11 BM and 5/9 CG subjects, with recovery of mean arterial pressure and animal survival for three hours (p < 0.05, Odds Ratio (OR) = 18.82 (0.85–415.3)). Time to stable hemostasis was shorter for the BM-treated group (4.8 ± 2.5 min vs. 58 ± 20.1 min; Median = 2, Interquartile Range (IQR) = 0 min vs. Median = 60, IQR = 120 min; p < 0.05) and experienced longer total stable hemostasis (175.2 ± 2.5 min vs. 92.4 ± 29.9 min; Median = 178, IQR = 0 min vs. Median = 120, IQR = 178 min; p < 0.05). Post-treatment blood loss was lower with BM (9.5 ± 2.4 mL/kg, Median = 10.52, IQR = 13.63 mL/kg) compared to CG (29.9 ± 9.9 mL/kg, Median = 29.38, IQR = 62.44 mL/kg) (p = 0.2875). Standard BM products weighed less compared to CG (6.9 ± 0.03 g vs. 20.2 ± 0.4 g) (p < 0.05) and absorbed less blood (3.4 ± 0.8 g vs. 41.9 ± 12.3 g) (p < 0.05). Fluoroscopic angiography showed recanalization in 5/11 (BM) and 0/5 (CG) surviving animals (p = 0.07, OR = 9.3 (0.41–208.8)). The wound stability challenge test resulted in wound re-bleeding in 1/11 (BM) and 5/5 (CG) surviving animals (p < 0.05, OR = 0.013 (0.00045–0.375)). Histologic evidence indicated no wound site, distal limb or

  19. Comparison of Topical Hemostatic Agents in a Swine Model of Extremity Arterial Hemorrhage: BloodSTOP iX Battle Matrix vs. QuikClot Combat Gauze.

    PubMed

    Li, Huixi; Wang, Lin; Alwaal, Amjad; Lee, Yung-Chin; Reed-Maldonado, Amanda; Spangler, Taylor A; Banie, Lia; O'Hara, Reginald B; Lin, Guiting

    2016-04-12

    BloodSTOP iX Battle Matrix (BM) and QuikClot Combat Gauze (CG) have both been used to treat traumatic bleeding. The purpose of this study was to examine the efficacy and initial safety of both products in a swine extremity arterial hemorrhage model, which mimics combat injury. Swine (37.13 ± 0.56 kg, NBM = 11, NCG = 9) were anesthetized and splenectomized. We then isolated the femoral arteries and performed a 6 mm arteriotomy. After 45 s of free bleeding, either BM or CG was applied. Fluid resuscitation was provided to maintain a mean arterial pressure of 65 mmHg. Animals were observed for three hours or until death. Fluoroscopic angiography and wound stability challenge tests were performed on survivors. Tissue samples were collected for histologic examination. Stable hemostasis was achieved in 11/11 BM and 5/9 CG subjects, with recovery of mean arterial pressure and animal survival for three hours (p < 0.05, Odds Ratio (OR) = 18.82 (0.85-415.3)). Time to stable hemostasis was shorter for the BM-treated group (4.8 ± 2.5 min vs. 58 ± 20.1 min; Median = 2, Interquartile Range (IQR) = 0 min vs. Median = 60, IQR = 120 min; p < 0.05) and experienced longer total stable hemostasis (175.2 ± 2.5 min vs. 92.4 ± 29.9 min; Median = 178, IQR = 0 min vs. Median = 120, IQR = 178 min; p < 0.05). Post-treatment blood loss was lower with BM (9.5 ± 2.4 mL/kg, Median = 10.52, IQR = 13.63 mL/kg) compared to CG (29.9 ± 9.9 mL/kg, Median = 29.38, IQR = 62.44 mL/kg) (p = 0.2875). Standard BM products weighed less compared to CG (6.9 ± 0.03 g vs. 20.2 ± 0.4 g) (p < 0.05) and absorbed less blood (3.4 ± 0.8 g vs. 41.9 ± 12.3 g) (p < 0.05). Fluoroscopic angiography showed recanalization in 5/11 (BM) and 0/5 (CG) surviving animals (p = 0.07, OR = 9.3 (0.41-208.8)). The wound stability challenge test resulted in wound re-bleeding in 1/11 (BM) and 5/5 (CG) surviving animals (p < 0.05, OR = 0.013 (0.00045-0.375)). Histologic evidence indicated no wound site, distal limb or major

  20. Salt-induced changes in cardiac phosphoproteome in a rat model of chronic renal failure.

    PubMed

    Su, Zhengxiu; Zhu, Hongguo; Zhang, Menghuan; Wang, Liangliang; He, Hanchang; Jiang, Shaoling; Hou, Fan Fan; Li, Aiqing

    2014-01-01

    Heart damage is widely present in patients with chronic kidney disease. Salt diet is the most important environmental factor affecting development of chronic renal failure and cardiovascular diseases. The proteins involved in chronic kidney disease -induced heart damage, especially their posttranslational modifications, remain largely unknown to date. Sprague-Dawley rats underwent 5/6 nephrectomy (chronic renal failure model) or sham operation were treated for 2 weeks with a normal-(0.4% NaCl), or high-salt (4% NaCl) diet. We employed TiO2 enrichment, iTRAQ labeling and liquid-chromatography tandem mass spectrometry strategy for phosphoproteomic profiling of left ventricular free walls in these animals. A total of 1724 unique phosphopeptides representing 2551 non-redundant phosphorylation sites corresponding to 763 phosphoproteins were identified. During normal salt feeding, 89 (54%) phosphopeptides upregulated and 76 (46%) phosphopeptides downregulated in chronic renal failure rats relative to sham rats. In chronic renal failure rats, high salt intake induced upregulation of 84 (49%) phosphopeptides and downregulation of 88 (51%) phosphopeptides. Database searches revealed that most of the identified phospholproteins were important signaling molecules such as protein kinases, receptors and phosphatases. These phospholproteins were involved in energy metabolism, cell communication, cell differentiation, cell death and other biological processes. The Search Tool for the Retrieval of Interacting Genes analysis revealed functional links among 15 significantly regulated phosphoproteins in chronic renal failure rats compared to sham group, and 23 altered phosphoproteins induced by high salt intake. The altered phosphorylation levels of two proteins involved in heart damage, lamin A and phospholamban were validated. Expression of the downstream genes of these two proteins, desmin and SERCA2a, were also analyzed.

  1. Creating a model of diseased artery damage and failure from healthy porcine aorta.

    PubMed

    Noble, Christopher; Smulders, Nicole; Green, Nicola H; Lewis, Roger; Carré, Matt J; Franklin, Steve E; MacNeil, Sheila; Taylor, Zeike A

    2016-07-01

    Large quantities of diseased tissue are required in the research and development of new generations of medical devices, for example for use in physical testing. However, these are difficult to obtain. In contrast, porcine arteries are readily available as they are regarded as waste. Therefore, reliable means of creating from porcine tissue physical models of diseased human tissue that emulate well the associated mechanical changes would be valuable. To this end, we studied the effect on mechanical response of treating porcine thoracic aorta with collagenase, elastase and glutaraldehyde. The alterations in mechanical and failure properties were assessed via uniaxial tension testing. A constitutive model composed of the Gasser-Ogden-Holzapfel model, for elastic response, and a continuum damage model, for the failure, was also employed to provide a further basis for comparison (Calvo and Peña, 2006; Gasser et al., 2006). For the concentrations used here it was found that: collagenase treated samples showed decreased fracture stress in the axial direction only; elastase treated samples showed increased fracture stress in the circumferential direction only; and glutaraldehyde samples showed no change in either direction. With respect to the proposed constitutive model, both collagenase and elastase had a strong effect on the fibre-related terms. The model more closely captured the tissue response in the circumferential direction, due to the smoother and sharper transition from damage initiation to complete failure in this direction. Finally, comparison of the results with those of tensile tests on diseased tissues suggests that these treatments indeed provide a basis for creation of physical models of diseased arteries.

  2. An overview of animal models for investigating the pathogenesis and therapeutic strategies in acute hepatic failure

    PubMed Central

    Tuñón, María Jesús; Alvarez, Marcelino; Culebras, Jesús M; González-Gallego, Javier

    2009-01-01

    Acute hepatic failure (AHF) is a severe liver injury accompanied by hepatic encephalopathy which causes multiorgan failure with an extremely high mortality rate, even if intensive care is provided. Management of severe AHF continues to be one of the most challenging problems in clinical medicine. Liver transplantation has been shown to be the most effective therapy, but the procedure is limited by shortage of donor organs. Although a number of clinical trials testing different liver assist devices are under way, these systems alone have no significant effect on patient survival and are only regarded as a useful approach to bridge patients with AHF to liver transplantation. As a result, reproducible experimental animal models resembling the clinical conditions are still needed. The three main approaches used to create an animal model for AHF are: surgical procedures, toxic liver injury and infective procedures. Most common models are based on surgical techniques (total/partial hepatectomy, complete/transient devascularization) or the use of hepatotoxic drugs (acetaminophen, galactosamine, thioacetamide, and others), and very few satisfactory viral models are available. We have recently developed a viral model of AHF by means of the inoculation of rabbits with the virus of rabbit hemorrhagic disease. This model displays biochemical and histological characteristics, and clinical features that resemble those in human AHF. In the present article an overview is given of the most widely used animal models of AHF, and their main advantages and disadvantages are reviewed. PMID:19575487

  3. Failure Predictions for VHTR Core Components using a Probabilistic Contiuum Damage Mechanics Model

    SciTech Connect

    Fok, Alex

    2013-10-30

    The proposed work addresses the key research need for the development of constitutive models and overall failure models for graphite and high temperature structural materials, with the long-term goal being to maximize the design life of the Next Generation Nuclear Plant (NGNP). To this end, the capability of a Continuum Damage Mechanics (CDM) model, which has been used successfully for modeling fracture of virgin graphite, will be extended as a predictive and design tool for the core components of the very high- temperature reactor (VHTR). Specifically, irradiation and environmental effects pertinent to the VHTR will be incorporated into the model to allow fracture of graphite and ceramic components under in-reactor conditions to be modeled explicitly using the finite element method. The model uses a combined stress-based and fracture mechanics-based failure criterion, so it can simulate both the initiation and propagation of cracks. Modern imaging techniques, such as x-ray computed tomography and digital image correlation, will be used during material testing to help define the baseline material damage parameters. Monte Carlo analysis will be performed to address inherent variations in material properties, the aim being to reduce the arbitrariness and uncertainties associated with the current statistical approach. The results can potentially contribute to the current development of American Society of Mechanical Engineers (ASME) codes for the design and construction of VHTR core components.

  4. Heart Failure

    MedlinePlus

    ... version of this page please turn Javascript on. Heart Failure What is Heart Failure? In heart failure, the heart cannot pump enough ... failure often experience tiredness and shortness of breath. Heart Failure is Serious Heart failure is a serious and ...

  5. Modelling of a Francis Turbine Runner Fatigue Failure Process Caused by Fluid-Structure Interaction

    NASA Astrophysics Data System (ADS)

    Lyutov, A.; Kryukov, A.; Cherny, S.; Chirkov, D.; Salienko, A.; Skorospelov, V.; Turuk, P.

    2016-11-01

    In the present paper considered is the problem of the numerical simulation of Francis turbine runner fatigue failure caused by fluid-structure interaction. The unsteady 3D flow is modeled simultaneously in the spiral chamber, each wicket gate and runner channels and in the draft tube using the Euler equations. Based on the unsteady runner loadings at each time step stresses in the whole runner are calculated using the elastic equilibrium equations solved with boundary element method. Set of static stress-strain states provides quasi-dynamics of runner cyclic loading. It is assumed that equivalent stresses in the runner are below the critical value after which irreversible plastic processes happen in the runner material. Therefore runner is subjected to the fatigue damage caused by high-cycle fatigue, in which the loads are generally low compared with the limit stress of the material. As a consequence, the stress state around the crack front can be fully characterized by linear elastic fracture mechanics. The place of runner cracking is determined as a point with maximal amplitude of stress oscillations. Stress pulsations amplitude is used to estimate the number of cycles until the moment of fatigue failure, number of loading cycles and oscillation frequency are used to calculate runner service time. Example of the real Francis runner which has encountered premature fatigue failure as a result of incorrect durability estimation is used to verify the developed numerical model.

  6. Regression modeling of the cumulative incidence function with missing causes of failure using pseudo-values.

    PubMed

    Moreno-Betancur, Margarita; Latouche, Aurélien

    2013-08-15

    Competing risks arise when patients may fail from several causes. Strategies for modeling event-specific quantities often assume that the cause of failure is known for all patients, but this is seldom the case. Several authors have addressed the problem of modeling the cause-specific hazard rates with missing causes of failure. In contrast, direct modeling of the cumulative incidence function has received little attention.We provide a general framework for regression modeling of this function in the missing cause setting, encompassing key models such as the Fine and Gray and additive models, by considering two extensions of the Andersen–Klein pseudo-value approach. The first extension is a novel inverse probability weighting method, whereas the second extension is based on a previously proposed multiple imputation procedure.We evaluated the gain in using these approaches with small samples in an extensive simulation study. We analyzed the data from an Eastern Cooperative Oncology Group breast cancer treatment clinical trial to illustrate the practical value and ease of implementation of the proposed methods.

  7. Failure Modeling of Titanium-6Al-4V and 2024-T3 Aluminum with the Johnson-Cook Material Model

    SciTech Connect

    Kay, G

    2002-09-16

    A validated Johnson-Cook model could be employed to perform simulations that conform to FAA standards for evaluating aircraft and engine designs for airworthiness and containment considerations. A previous LLNL report [1] described the motivation for using the Johnson-Cook material model in simulations involving engine containment and the effect of uncontained engine debris on aircraft structures. In that report, experimental studies of the deformation and failure behavior of Ti-6Al-4V and 2024-T3 aluminum at high strain rates and large strains were conducted. The report also describes the generation of material constants for the Johnson-Cook strength model. This report describes the determination and validation of parameters for Ti-6Al-4V and 2024-T3 aluminum that can be used in the failure portion of the Johnson-Cook material.

  8. Overview of Threats and Failure Models for Safety-Relevant Computer-Based Systems

    NASA Technical Reports Server (NTRS)

    Torres-Pomales, Wilfredo

    2015-01-01

    This document presents a high-level overview of the threats to safety-relevant computer-based systems, including (1) a description of the introduction and activation of physical and logical faults; (2) the propagation of their effects; and (3) function-level and component-level error and failure mode models. These models can be used in the definition of fault hypotheses (i.e., assumptions) for threat-risk mitigation strategies. This document is a contribution to a guide currently under development that is intended to provide a general technical foundation for designers and evaluators of safety-relevant systems.

  9. Proportional hazards model for competing risks data with missing cause of failure

    PubMed Central

    Hyun, Seunggeun; Sun, Yanqing

    2012-01-01

    We consider the semiparametric proportional hazards model for the cause-specific hazard function in analysis of competing risks data with missing cause of failure. The inverse probability weighted equation and augmented inverse probability weighted equation are proposed for estimating the regression parameters in the model, and their theoretical properties are established for inference. Simulation studies demonstrate that the augmented inverse probability weighted estimator is doubly robust and the proposed method is appropriate for practical use. The simulations also compare the proposed estimators with the multiple imputation estimator of Lu and Tsiatis (2001). The application of the proposed method is illustrated using data from a bone marrow transplant study. PMID:22468017

  10. User-defined Material Model for Thermo-mechanical Progressive Failure Analysis

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.

    2008-01-01

    Previously a user-defined material model for orthotropic bimodulus materials was developed for linear and nonlinear stress analysis of composite structures using either shell or solid finite elements within a nonlinear finite element analysis tool. Extensions of this user-defined material model to thermo-mechanical progressive failure analysis are described, and the required input data are documented. The extensions include providing for temperature-dependent material properties, archival of the elastic strains, and a thermal strain calculation for materials exhibiting a stress-free temperature.

  11. In Vivo Hemodynamic Performance Evaluation of Novel Electrocardiogram-Synchronized Pulsatile and Nonpulsatile Extracorporeal Life Support Systems in an Adult Swine Model.

    PubMed

    Wang, Shigang; Izer, Jenelle M; Clark, Joseph B; Patel, Sunil; Pauliks, Linda; Kunselman, Allen R; Leach, Donald; Cooper, Timothy K; Wilson, Ronald P; Ündar, Akif

    2015-07-01

    The primary objective of this study was to evaluate a novel electrocardiogram (ECG)-synchronized pulsatile extracorporeal life support (ECLS) system for adult partial mechanical circulatory support for adequate quality of pulsatility and enhanced hemodynamic energy generation in an in vivo animal model. The secondary aim was to assess end-organ protection during nonpulsatile versus synchronized pulsatile flow mode. Ten adult swine were randomly divided into a nonpulsatile group (NP, n = 5) and pulsatile group (P, n = 5), and placed on ECLS for 24 h using an i-cor system consisting of an i-cor diagonal pump, an iLA membrane ventilator, an 18 Fr femoral arterial cannula and a 23/25 Fr femoral venous cannula. Trials were conducted at a flow rate of 2.5 L/min using nonpulsatile or pulsatile mode (with assist ratio 1:1). Real-time pressure and flow data were recorded using a custom-based data acquisition system. To the best of our knowledge, the oxygenator and circuit pressure drops were the lowest for any available system in both groups. The ECG-synchronized i-cor ECLS system was able to trigger pulsatile flow in the porcine model. After 24-h ECLS, energy equivalent pressure, surplus hemodynamic energy, and total hemodynamic energy at preoxygenator and prearterial cannula sites were significantly higher in the P group than those in the NP group (P < 0.05). Urine output was higher in P versus NP (3379 ± 443 mL vs. NP, 2598 ± 1012 mL), and the P group seemed to require less inotropic support, but both did not reach statistical significances (P > 0.05). The novel i-cor system performed well in the nonpulsatile and ECG-synchronized pulsatile mode in an adult animal ECLS model. The iLA membrane oxygenator had an extremely lower transmembrane pressure gradient and excellent gas exchange capability. Our findings suggest that ECG-triggered pulsatile ECLS provides superior end-organ protection with improved renal function and systemic vascular

  12. Evaluation of the risk of classical swine fever (CSF) spread from backyard pigs to other domestic pigs by using the spatial stochastic disease spread model Be-FAST: the example of Bulgaria.

    PubMed

    Martínez-López, Beatriz; Ivorra, Benjamin; Ramos, Angel Manuel; Fernández-Carrión, Eduardo; Alexandrov, Tsviatko; Sánchez-Vizcaíno, José Manuel

    2013-07-26

    The study presented here is one of the very first aimed at exploring the potential spread of classical swine fever (CSF) from backyard pigs to other domestic pigs. Specifically, we used a spatial stochastic spread model, called Be-FAST, to evaluate the potential spread of CSF virus (CSFV) in Bulgaria, which holds a large number of backyards (96% of the total number of pig farms) and is one of the very few countries for which backyard pigs and farm counts are available. The model revealed that, despite backyard pigs being very likely to become infected, infections from backyard pigs to other domestic pigs were rare. In general, the magnitude and duration of the CSF simulated epidemics were small, with a median [95% PI] number of infected farms per epidemic of 1 [1,4] and a median [95% PI] duration of the epidemic of 44 [17,101] days. CSFV transmission occurs primarily (81.16%) due to indirect contacts (i.e. vehicles, people and local spread) whereas detection of infected premises was mainly (69%) associated with the observation of clinical signs on farm rather than with implementation of tracing or zoning. Methods and results of this study may support the implementation of risk-based strategies more cost-effectively to prevent, control and, ultimately, eradicate CSF from Bulgaria. The model may also be easily adapted to other countries in which the backyard system is predominant. It can also be used to simulate other similar diseases such as African swine fever.

  13. Implementation and validation of an economic module in the Be-FAST model to predict costs generated by livestock disease epidemics: Application to classical swine fever epidemics in Spain.

    PubMed

    Fernández-Carrión, E; Ivorra, B; Martínez-López, B; Ramos, A M; Sánchez-Vizcaíno, J M

    2016-04-01

    Be-FAST is a computer program based on a time-spatial stochastic spread mathematical model for studying the transmission of infectious livestock diseases within and between farms. The present work describes a new module integrated into Be-FAST to model the economic consequences of the spreading of classical swine fever (CSF) and other infectious livestock diseases within and between farms. CSF is financially one of the most damaging diseases in the swine industry worldwide. Specifically in Spain, the economic costs in the two last CSF epidemics (1997 and 2001) reached jointly more than 108 million euros. The present analysis suggests that severe CSF epidemics are associated with significant economic costs, approximately 80% of which are related to animal culling. Direct costs associated with control measures are strongly associated with the number of infected farms, while indirect costs are more strongly associated with epidemic duration. The economic model has been validated with economic information around the last outbreaks in Spain. These results suggest that our economic module may be useful for analysing and predicting economic consequences of livestock disease epidemics.

  14. Multiscale model of the human cardiovascular system: Description of heart failure and comparison of contractility indices.

    PubMed

    Kosta, S; Negroni, J; Lascano, E; Dauby, P C

    2017-02-01

    A multiscale model of the cardiovascular system is presented. Hemodynamics is described by a lumped parameter model, while heart contraction is described at the cellular scale. An electrophysiological model and a mechanical model were coupled and adjusted so that the pressure and volume of both ventricles are linked to the force and length of a half-sarcomere. Particular attention was paid to the extreme values of the sarcomere length, which must keep physiological values. This model is able to reproduce healthy behavior, preload variations experiments, and ventricular failure. It also allows to compare the relevance of standard cardiac contractility indices. This study shows that the theoretical gold standard for assessing cardiac contractility, namely the end-systolic elastance, is actually load-dependent and therefore not a reliable index of cardiac contractility.

  15. A blackboard model of an expert system for failure mode and effects analysis

    NASA Astrophysics Data System (ADS)

    Russomanno, David J.; Bonnell, Ronald D.; Bowles, John B.

    The design of an expert system to assist in performing a failure mode and effects analysis (FMEA) is approached from a knowledge-use-level perspective to provide a thorough understanding of the problem and insight into the knowledge and expertise needed to automate the FMEA process. A blackboard model is a conceptual model that provides the organizational principles required for the design of an expert system without actually specifying its realization. In the blackboard model of an intelligent FMEA, the system is functionally decomposed into a set of knowledge sources, each containing the knowledge associated with a subfunction of the FMEA process. The conceptual model derived can be used to evaluate attempts to automate the FMEA process, and it can serve as the foundation for further research into automating the FMEA process. An example is presented illustrating the interaction among the knowledge sources in the blackboard model to construct a FMEA for a domestic hot water heater.

  16. Observations, models, and mechanisms of failure of surface rocks surrounding planetary surface loads

    NASA Technical Reports Server (NTRS)

    Schultz, R. A.; Zuber, M. T.

    1994-01-01

    Geophysical models of flexural stresses in an elastic lithosphere due to an axisymmetric surface load typically predict a transition with increased distance from the center of the load of radial thrust faults to strike-slip faults to concentric normal faults. These model predictions are in conflict with the absence of annular zones of strike-slip faults around prominent loads such as lunar maria, Martian volcanoes, and the Martian Tharsis rise. We suggest that this paradox arises from difficulties in relating failure criteria for brittle rocks to the stress models. Indications that model stresses are inappropriate for use in fault-type prediction include (1) tensile principal stresses larger than realistic values of rock tensile strength, and/or (2) stress differences significantly larger than those allowed by rock-strength criteria. Predictions of surface faulting that are consistent with observations can be obtained instead by using tensile and shear failure criteria, along with calculated stress differences and trajectories, with model stress states not greatly in excess of the maximum allowed by rock fracture criteria.

  17. Modeling Progressive Failure of Bonded Joints Using a Single Joint Finite Element

    NASA Technical Reports Server (NTRS)

    Stapleton, Scott E.; Waas, Anthony M.; Bednarcyk, Brett A.

    2010-01-01

    Enhanced finite elements are elements with an embedded analytical solution which can capture detailed local fields, enabling more efficient, mesh-independent finite element analysis. In the present study, an enhanced finite element is applied to generate a general framework capable of modeling an array of joint types. The joint field equations are derived using the principle of minimum potential energy, and the resulting solutions for the displacement fields are used to generate shape functions and a stiffness matrix for a single joint finite element. This single finite element thus captures the detailed stress and strain fields within the bonded joint, but it can function within a broader structural finite element model. The costs associated with a fine mesh of the joint can thus be avoided while still obtaining a detailed solution for the joint. Additionally, the capability to model non-linear adhesive constitutive behavior has been included within the method, and progressive failure of the adhesive can be modeled by using a strain-based failure criteria and re-sizing the joint as the adhesive fails. Results of the model compare favorably with experimental and finite element results.

  18. Global migration of influenza A viruses in swine

    PubMed Central

    Nelson, Martha I.; Viboud, Cécile; Vincent, Amy L.; Culhane, Marie R.; Detmer, Susan E.; Wentworth, David E.; Rambaut, Andrew; Suchard, Marc A.; Holmes, Edward C.; Lemey, Philippe

    2015-01-01

    The complex and unresolved evolutionary origins of the 2009 H1N1 influenza pandemic exposed major gaps in our knowledge of the global spatial ecology and evolution of influenza A viruses in swine (swIAVs). Here we undertake an expansive phylogenetic analysis of swIAV sequence data and demonstrate that the global live swine trade strongly predicts the spatial dissemination of swIAVs, with Europe and North America acting as sources of viruses in Asian countries. In contrast, China has the world’s largest swine population but is not a major exporter of live swine, and is not an important source of swIAVs in neighboring Asian countries or globally. A meta-population simulation model incorporating trade data predicts that the global ecology of swIAVs is more complex than previously thought, and the US and China’s large swine populations are unlikely to be representative of swIAV diversity in their respective geographic regions, requiring independent surveillance efforts throughout Latin America and Asia. PMID:25813399

  19. Global migration of influenza A viruses in swine.

    PubMed

    Nelson, Martha I; Viboud, Cécile; Vincent, Amy L; Culhane, Marie R; Detmer, Susan E; Wentworth, David E; Rambaut, Andrew; Suchard, Marc A; Holmes, Edward C; Lemey, Philippe

    2015-03-27

    The complex and unresolved evolutionary origins of the 2009 H1N1 influenza pandemic exposed major gaps in our knowledge of the global spatial ecology and evolution of influenza A viruses in swine (swIAVs). Here we undertake an expansive phylogenetic analysis of swIAV sequence data and demonstrate that the global live swine trade strongly predicts the spatial dissemination of swIAVs, with Europe and North America acting as sources of viruses in Asian countries. In contrast, China has the world's largest swine population but is not a major exporter of live swine, and is not an important source of swIAVs in neighbouring Asian countries or globally. A meta-population simulation model incorporating trade data predicts that the global ecology of swIAVs is more complex than previously thought, and the United States and China's large swine populations are unlikely to be representative of swIAV diversity in their respective geographic regions, requiring independent surveillance efforts throughout Latin America and Asia.

  20. Model for end-stage liver disease predicts right ventricular failure in patients with left ventricular assist devices.

    PubMed

    Yost, Gardner L; Coyle, Laura; Bhat, Geetha; Tatooles, Antone J

    2016-03-01

    High rates of right ventricular failure continue to affect postoperative outcomes in patients implanted with left ventricular assist devices (LVADs). Development of right ventricular failure and implantation with right ventricular assist devices is known to be associated with significantly increased mortality. The model for end-stage liver disease (MELD) score is an effective means of evaluating liver dysfunction. We investigated the prognostic utility of postoperative MELD on post-LVAD implantation outcomes. MELD scores, demographic data, and outcomes including length of stay, survival, and postoperative right ventricular failure were collected for 256 patients implanted with continuous flow LVADs. Regression and Kaplan-Meier analyses were used to investigate the relationship between MELD and all outcomes. Increased MELD score was found to be an independent predictor of both right heart failure and necessity for RVAD implantation (OR 1.097, CI 1.040-1.158, p = 0.001; OR 1.121, CI 1.015, p = 0.024, respectively). Patients with RV failure and who underwent RVAD implantation had reduced postoperative survival compared to patients with RV dysfunction (no RV failure = 651.4 ± 609.8 days, RV failure = 392.6 ± 444.8 days, RVAD = 89.3 ± 72.8 days; p < 0.001). In conclusion, MELD can be used to reliably predict postoperative right heart failure and the necessity for RVAD implantation. Those patients with RV failure and RVADs experience significantly increased postoperative mortality compared to those without RV dysfunction.

  1. Qualitative risk assessment in a data-scarce environment: a model to assess the impact of control measures on spread of African Swine Fever.

    PubMed

    Wieland, Barbara; Dhollander, Sofie; Salman, Mo; Koenen, Frank

    2011-04-01

    In the absence of data, qualitative risk assessment frameworks have proved useful to assess risks associated with animal health diseases. As part of a scientific opinion for the European Commission (EC) on African Swine Fever (ASF), a working group of the European Food Safety Authority (EFSA) assessed the risk of ASF remaining endemic in Trans Caucasus Countries (TCC) and the Russian Federation (RF) and the risk of ASF becoming endemic in the EU if disease were introduced. The aim was to develop a tool to evaluate how current control or preventive measures mitigate the risk of spread and giving decision makers the means to review how strengthening of surveillance and control measures would mitigate the risk of disease spread. Based on a generic model outlining disease introduction, spread and endemicity in a region, the impact of risk mitigation measures on spread of disease was assessed for specific risk questions. The resulting hierarchical models consisted of key steps containing several sub-steps. For each step of the risk pathways risk estimates were determined by the expert group based on existing data or through expert opinion elicitation. Risk estimates were combined using two different combination matrices, one to combine estimates of independent steps and one to combine conditional probabilities. The qualitative risk assessment indicated a moderate risk that ASF will remain endemic in current affected areas in the TCC and RF and a high risk of spread to currently unaffected areas. If introduced into the EU, ASF is likely to be controlled effectively in the production sector with high or limited biosecurity. In the free range production sector, however, there is a moderate risk of ASF becoming endemic due to wild boar contact, non-compliance with animal movement bans, and difficult access to all individual pigs upon implementation of control measures. This study demonstrated the advantages of a systematic framework to assist an expert panel to carry out a

  2. H1N1 Flu (Swine Flu)

    MedlinePlus

    ... prevent or treat swine flu. There is a vaccine available to protect against swine flu. You can help prevent the spread of germs that cause respiratory illnesses like influenza by Covering your nose and mouth with a ...

  3. The respiratory DC/macrophage network at steady-state and upon influenza infection in the swine biomedical model.

    PubMed

    Maisonnasse, P; Bouguyon, E; Piton, G; Ezquerra, A; Urien, C; Deloizy, C; Bourge, M; Leplat, J-J; Simon, G; Chevalier, C; Vincent-Naulleau, S; Crisci, E; Montoya, M; Schwartz-Cornil, I; Bertho, N

    2016-07-01

    Human and mouse respiratory tracts show anatomical and physiological differences, which will benefit from alternative experimental models for studying many respiratory diseases. Pig has been recognized as a valuable biomedical model, in particular for lung transplantation or pathologies such as cystic fibrosis and influenza infection. However, there is a lack of knowledge about the porcine respiratory immune system. Here we segregated and studied six populations of pig lung dendritic cells (DCs)/macrophages (Mθs) as follows: conventional DCs (cDC) 1 and cDC2, inflammatory monocyte-derived DCs (moDCs), monocyte-derived Mθs, and interstitial and alveolar Mθs. The three DC subsets present migratory and naive T-cell stimulation capacities. As observed in human and mice, porcine cDC1 and cDC2 were able to induce T-helper (Th)1 and Th2 responses, respectively. Interestingly, porcine moDCs increased in the lung upon influenza infection, as observed in the mouse model. Pig cDC2 shared some characteristics observed in human but not in mice, such as the expression of FCɛRIα and Langerin, and an intra-epithelial localization. This work, by unraveling the extended similarities of the porcine and human lung DC/Mθ networks, highlights the relevance of pig, both as an exploratory model of DC/Mθ functions and as a model for human inflammatory lung pathologies.

  4. Wakame (Undaria pinnatifida ) modulates hyperphosphatemia in a rat model of chronic renal failure.

    PubMed

    Katai, Kanako; Iwamoto, Aya; Kimura, Yuka; Oshima, Yuki; Arioka, Saori; Morimi, Yuki; Omuro, Ayaka; Nakasa, Teruko

    2015-01-01

    In chronic renal failure, inorganic phosphate (Pi) retention speeds up the progression to end-stage renal disease. The current therapy for hyperphosphatemia in patients with chronic renal failure consists of dietary Pi restriction combined with administration of Pi binders, but each therapy has practical problems. Thus, the discovery of foods or nutrients that inhibit Pi absorption may be useful for the treatment of hyperphosphatemia. In the present study, we investigated whether wakame (Undaria pinnatifida) is a useful food for the prevention of hyperphosphatemia in a rat model of renal failure. Feeding a diet containing 5% wakame significantly decreased plasma and urinary Pi levels and increased the amount of fecal Pi. In addition, wakame significantly reduced plasma blood urea nitrogen and plasma Pi levels in 5/6 nephrectomized rats fed a high-Pi diet. Biochemical analyses showed that the reduction of intestinal Pi absorption is the main reason for the decrease in plasma Pi levels in rats fed a diet containing wakame. In addition, feeding alginic acid and fucoidan, major components of wakame fiber, was effective in reducing plasma Pi levels in normal rats. Finally, we concluded that wakame may be a useful food for the prevention of hyperphosphatemia in rodents.

  5. An exact renormalization model for earthquakes and material failure: Statics and dynamics

    SciTech Connect

    Newman, W.I. |; Gabrielov, A.M. |; Durand, T.A.; Phoenix, S.L.; Turcotte, D.L.

    1993-09-12

    Earthquake events are well-known to prams a variety of empirical scaling laws. Accordingly, renormalization methods offer some hope for understanding why earthquake statistics behave in a similar way over orders of magnitude of energy. We review the progress made in the use of renormalization methods in approaching the earthquake problem. In particular, earthquake events have been modeled by previous investigators as hierarchically organized bundles of fibers with equal load sharing. We consider by computational and analytic means the failure properties of such bundles of fibers, a problem that may be treated exactly by renormalization methods. We show, independent of the specific properties of an individual fiber, that the stress and time thresholds for failure of fiber bundles obey universal, albeit different, staling laws with respect to the size of the bundles. The application of these results to fracture processes in earthquake events and in engineering materials helps to provide insight into some of the observed patterns and scaling-in particular, the apparent weakening of earthquake faults and composite materials with respect to size, and the apparent emergence of relatively well-defined stresses and times when failure is seemingly assured.

  6. Modeling of Electrical Cable Failure in a Dynamic Assessment of Fire Risk

    NASA Astrophysics Data System (ADS)

    Bucknor, Matthew D.

    Fires at a nuclear power plant are a safety concern because of their potential to defeat the redundant safety features that provide a high level of assurance of the ability to safely shutdown the plant. One of the added complexities of providing protection against fires is the need to determine the likelihood of electrical cable failure which can lead to the loss of the ability to control or spurious actuation of equipment that is required for safe shutdown. A number of plants are now transitioning from their deterministic fire protection programs to a risk-informed, performance based fire protection program according to the requirements of National Fire Protection Association (NFPA) 805. Within a risk-informed framework, credit can be taken for the analysis of fire progression within a fire zone that was not permissible within the deterministic framework of a 10 CFR 50.48 Appendix R safe shutdown analysis. To perform the analyses required for the transition, plants need to be able to demonstrate with some level of assurance that cables related to safe shutdown equipment will not be compromised during postulated fire scenarios. This research contains the development of new cable failure models that have the potential to more accurately predict electrical cable failure in common cable bundle configurations. Methods to determine the thermal properties of the new models from empirical data are presented along with comparisons between the new models and existing techniques used in the nuclear industry today. A Dynamic Event Tree (DET) methodology is also presented which allows for the proper treatment of uncertainties associated with fire brigade intervention and its effects on cable failure analysis. Finally a shielding analysis is performed to determine the effects on the temperature response of a cable bundle that is shielded from a fire source by an intervening object such as another cable tray. The results from the analyses demonstrate that models of similar

  7. Intravenous Fat Emulsion Therapy Versus Sodium Bicarbonate Effect on Hypotension and QRS Measurement in a Swine Model (Sus scrofa) of Diphenhydramine Toxicity

    DTIC Science & Technology

    2012-11-13

    Intralipid, sodium bicarbonate, intravenous fat emulsion, poisoning, overdose, toxicity, and antidote U U U SAR Shawn M. Varney, MD 210-916-8727 WHASC...fat emulsion (I FE) did not perform better than the standard antidote (sodium bicarbonate- SB) in an amitriptyline-induced cardiotoxic swine mode...group in any hemodynamic parameter or electrocardiogram interval - mean heart rate (HR), systolic blood pressure (SBP), mean arterial pressure (MAP

  8. The Effect of Hypotensive Resuscitation and Fluid Type on Mortality, Bleeding, Coagulation and Dysfunctional Inflammation in a Swine Grade V Liver Injury Model

    DTIC Science & Technology

    2008-01-01

    prior to surgery , except for water ad libitum. We pre- anesthetized the swine with an intramuscular injection of 8mg/kg Telazol® (Fort Dodge Animal...fluxuations, and response to painful stimuli at the nasal septum and forefoot . All efforts were made to ensure the study team remained blinded to the...Injured Patient. World Journal of Surgery . 2007;31:1055-1065. 9. Cho SD, Holcomb JB, Tieu BH, Englhart MS, Morris MS, Karahan ZA, Underwood SA, Muller

  9. Toward Failure Modeling In Complex Dynamic Systems: Impact of Design and Manufacturing Variations

    NASA Technical Reports Server (NTRS)

    Tumer, Irem Y.; McAdams, Daniel A.; Clancy, Daniel (Technical Monitor)

    2001-01-01

    When designing vehicle vibration monitoring systems for aerospace devices, it is common to use well-established models of vibration features to determine whether failures or defects exist. Most of the algorithms used for failure detection rely on these models to detect significant changes during a flight environment. In actual practice, however, most vehicle vibration monitoring systems are corrupted by high rates of false alarms and missed detections. Research conducted at the NASA Ames Research Center has determined that a major reason for the high rates of false alarms and missed detections is the numerous sources of statistical variations that are not taken into account in the. modeling assumptions. In this paper, we address one such source of variations, namely, those caused during the design and manufacturing of rotating machinery components that make up aerospace systems. We present a novel way of modeling the vibration response by including design variations via probabilistic methods. The results demonstrate initial feasibility of the method, showing great promise in developing a general methodology for designing more accurate aerospace vehicle vibration monitoring systems.

  10. Minimum space allowance for transportation of swine by road.

    PubMed

    Whiting, Terry L; Brandt, Steve

    2002-03-01

    Space allowance for animals in transit is a consistent concern in many countries that are developing codes of practice and regulations to assure humane treatment of food producing animals. The minimum space allowance requirements for a broad size range of swine in transit has not been well described or scientifically substantiated. A maximal loading pressure recommendation for pigs weighing from 5 to 250 kg was derived by a consultative process involving the swine transportation industry, animal welfare groups, and a literature review. The recommended maximal loading pressure under ideal conditions for swine loaded in groups can be described as a hoerl model y = (37.53)(0.9969)w(W0.5008), where y = loading pressure in kg body weight/m2 and W = average animal body weight in kilograms.

  11. Strength Evaluation and Failure Prediction of Short Carbon Fiber Reinforced Nylon Spur Gears by Finite Element Modeling

    NASA Astrophysics Data System (ADS)

    Hu, Zhong; Hossan, Mohammad Robiul

    2013-06-01

    In this paper, short carbon fiber reinforced nylon spur gear pairs, and steel and unreinforced nylon spur gear pairs have been selected for study and comparison. A 3D finite element model was developed to simulate the multi-axial stress-strain behaviors of the gear tooth. Failure prediction has been conducted based on the different failure criteria, including Tsai-Wu criterion. The tooth roots, where has stress concentration and the potential for failure, have been carefully investigated. The modeling results show that the short carbon fiber reinforced nylon gear fabricated by properly controlled injection molding processes can provide higher strength and better performance.

  12. A Cutaneous Full-Thickness Liquid Sulfur Mustard Burn Model in Weanling Swine: Clinical Pathology and Urinary Excretion of Thiodiglycol

    DTIC Science & Technology

    2000-01-01

    studies.17 Meyer and co-workers con- cluded that, among the domestic species, the pig pro- vides the most suitable experimental model for derma ...i.d. DB-5 bonded phase column of 0.25 (Jim film thickness (J&W Scientific, Folsom, CA). Helium was used as the carrier gas at a column head pressure

  13. Improved process model for ammonia volatilization from anaerobic swine lagoons under varying wind speeds and gas bubbling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ammonia volatilization from treatment lagoons varies widely with the lagoon water total ammonia concentration, pH, temperature, suspended solids, atmospheric ammonia concentration above the water surface, and wind speed. Ammonia emissions were estimated with a process-based mechanistic model using a...

  14. Modeling cascading failures with the crisis of trust in social networks

    NASA Astrophysics Data System (ADS)

    Yi, Chengqi; Bao, Yuanyuan; Jiang, Jingchi; Xue, Yibo

    2015-10-01

    In social networks, some friends often post or disseminate malicious information, such as advertising messages, informal overseas purchasing messages, illegal messages, or rumors. Too much malicious information may cause a feeling of intense annoyance. When the feeling exceeds a certain threshold, it will lead social network users to distrust these friends, which we call the crisis of trust. The crisis of trust in social networks has already become a universal concern and an urgent unsolved problem. As a result of the crisis of trust, users will cut off their relationships with some of their untrustworthy friends. Once a few of these relationships are made unavailable, it is likely that other friends will decline trust, and a large portion of the social network will be influenced. The phenomenon in which the unavailability of a few relationships will trigger the failure of successive relationships is known as cascading failure dynamics. To our best knowledge, no one has formally proposed cascading failures dynamics with the crisis of trust in social networks. In this paper, we address this potential issue, quantify the trust between two users based on user similarity, and model the minimum tolerance with a nonlinear equation. Furthermore, we construct the processes of cascading failures dynamics by considering the unique features of social networks. Based on real social network datasets (Sina Weibo, Facebook and Twitter), we adopt two attack strategies (the highest trust attack (HT) and the lowest trust attack (LT)) to evaluate the proposed dynamics and to further analyze the changes of the topology, connectivity, cascading time and cascade effect under the above attacks. We numerically find that the sparse and inhomogeneous network structure in our cascading model can better improve the robustness of social networks than the dense and homogeneous structure. However, the network structure that seems like ripples is more vulnerable than the other two network

  15. Development of Accelerated Coronary Atherosclerosis Model Using Low Density Lipoprotein Receptor Knock-Out Swine with Balloon Injury

    PubMed Central

    Ogita, Manabu; Miyauchi, Katsumi; Onishi, Akira; Tsuboi, Shuta; Wada, Hideki; Konishi, Hirokazu; Naito, Ryo; Dohi, Tomotaka; Kasai, Takatoshi; Kojima, Yuko; Schwartz, Robert S.; Daida, Hiroyuki

    2016-01-01

    Background Several animal models have facilitated the evaluation and pathological understanding of atherosclerosis, but a definitive animal model of coronary atherosclerosis is not available. We therefore developed low density lipoprotein receptor knockout (LDLR-KO) pigs with hypercholesterolemia, a model which rapidly developed coronary atherosclerosis following balloon injury. Methods and Results We deleted LDLR exon regions from cultured porcine fetal fibroblasts and cloned LDLR knockout (LDLR-KO) embryos microinjecting fetal fibroblast nuclei into enucleated oocytes. Twelve LDLR-KO pigs were fed a 2.0% cholesterol and 20% fat diet. Baseline serum LDL cholesterol level was 510.0±86.1 mg/dL. Balloon injury was created in 46 coronary segments and necropsy were obtained 2, 4, 8 and 12 weeks later. Coronary artery sections were reviewed to evaluate lesion progression. We found lipid accumulation with foam cells and inflammatory cells beginning four weeks after balloon injury. The mean ratio of macrophages to plaque area was significantly higher in the four- weeks and eight-week animals compared with those at 2-weeks (8.79% ± 5.98% and 17.00% ± 10.38% vs. 1.14% ± 1.88%, P < 0.0001). At 12 weeks the ratio decreased toward the level at 2 week level (4.00% ± 4.56%, P = 0.66 vs. baseline). Advanced coronary atherosclerotic lesions contained lipid pools at eight-weeks with fibrous components beginning at 12 weeks. Conclusions We developed a model of rapid coronary atherosclerosis using LDLR KO pigs with balloon injury. This model may be useful for preclinical evaluation of medication or devices, and may also help investigate mechanisms of plaque progression. PMID:27631974

  16. Impact performance characteristics and modeling failure mechanisms of pultruded glass-graphite/epoxy hybrid composite beams

    NASA Astrophysics Data System (ADS)

    Kowsika, Murthy V. S. L. N.

    In this study, investigation was performed to comprehend the influence of hybridization on the impact performance in terms of the energy absorption characteristics and delamination fracture toughness of pultruded uni-directional composite materials. In order to evaluate the improvements/changes in the impact performance as a result of hybridization, apart from considering mono-fiber reinforced all-graphite and all-glass composites, several types of sandwich hybrid composites comprising of both graphite as well as glass fibers were included in the investigation. By keeping a constant overall fiber content, the lay-up sequence and the volume fraction of each type of fiber are altered in these pultruded composites to determine the trend in the mechanical behavior as a result of hybridization. The response of pultruded all-graphite, all-glass and glass-graphite hybrid composites is evaluated under two different incident impact energy conditions. A high incident energy (HIE) and a low incident energy (LIE) of impact are chosen to cause either complete fracture or induce delamination, respectively, for assessing the energy absorption characteristics (crashworthiness) and delamination fracture toughness of these composites. Finite element modeling is performed under static as well as dynamic loading conditions to simulate the stress distribution and to predict the energy absorption behavior of composites. Progressive damage due to sequential ply failure was modeled by utilizing the failure strain data obtained from static and HTE impact tests for analyzing the post-initial ply failure characteristics of pultruded composites. Finite element modeling was also performed to simulate delamination crack propagation at various levels through the thickness. The strain energy release rate computed using the virtual crack closure technique was monitored to determine the likelihood of delamination crack propagation with increment in crack growth for the pultruded composites under

  17. A stochastic model for soft tissue failure using acoustic emission data.

    PubMed

    Sánchez-Molina, D; Martínez-González, E; Velázquez-Ameijide, J; Llumà, J; Rebollo Soria, M C; Arregui-Dalmases, C

    2015-11-01

    The strength of soft tissues is due mainly to collagen fibers. In most collagenous tissues, the arrangement of the fibers is random, but has preferred directions. The random arrangement makes it difficult to make deterministic predictions about the starting process of fiber breaking under tension. When subjected to tensile stress the fibers are progressively straighten out and then start to be stretched. At the beginning of fiber breaking, some of the fibers reach their maximum tensile strength and break down while some others remain unstressed (this latter fibers will assume then bigger stress until they eventually arrive to their failure point). In this study, a sample of human esophagi was subjected to a tensile breaking of fibers, up to the complete failure of the specimen. An experimental setup using Acoustic Emission to detect the elastic energy released is used during the test to detect the location of the emissions and the number of micro-failures per time unit. The data were statistically analyzed in order to be compared to a stochastic model which relates the level of stress in the tissue and the probability of breaking given the number of previously broken fibers (i.e. the deterioration in the tissue). The probability of a fiber breaking as the stretch increases in the tissue can be represented by a non-homogeneous Markov process which is the basis of the stochastic model proposed. This paper shows that a two-parameter model can account for the fiber breaking and the expected distribution for ultimate stress is a Fréchet distribution.

  18. 9 CFR 311.5 - Swine erysipelas.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 false Swine erysipelas. 311.5 Section 311.5... CERTIFICATION DISPOSAL OF DISEASED OR OTHERWISE ADULTERATED CARCASSES AND PARTS § 311.5 Swine erysipelas. Carcasses affected with swine erysipelas which is acute or generalized, or which show systemic change,...

  19. 9 CFR 311.5 - Swine erysipelas.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Swine erysipelas. 311.5 Section 311.5... CERTIFICATION DISPOSAL OF DISEASED OR OTHERWISE ADULTERATED CARCASSES AND PARTS § 311.5 Swine erysipelas. Carcasses affected with swine erysipelas which is acute or generalized, or which show systemic change,...

  20. 9 CFR 311.5 - Swine erysipelas.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Swine erysipelas. 311.5 Section 311.5... CERTIFICATION DISPOSAL OF DISEASED OR OTHERWISE ADULTERATED CARCASSES AND PARTS § 311.5 Swine erysipelas. Carcasses affected with swine erysipelas which is acute or generalized, or which show systemic change,...

  1. 9 CFR 309.9 - Swine erysipelas.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Swine erysipelas. 309.9 Section 309.9... CERTIFICATION ANTE-MORTEM INSPECTION § 309.9 Swine erysipelas. All hogs plainly showing on ante-mortem inspection that they are affected with acute swine erysipelas shall be identified as U.S. Condemned...

  2. 9 CFR 311.5 - Swine erysipelas.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Swine erysipelas. 311.5 Section 311.5... CERTIFICATION DISPOSAL OF DISEASED OR OTHERWISE ADULTERATED CARCASSES AND PARTS § 311.5 Swine erysipelas. Carcasses affected with swine erysipelas which is acute or generalized, or which show systemic change,...

  3. 9 CFR 309.9 - Swine erysipelas.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 false Swine erysipelas. 309.9 Section 309.9... CERTIFICATION ANTE-MORTEM INSPECTION § 309.9 Swine erysipelas. All hogs plainly showing on ante-mortem inspection that they are affected with acute swine erysipelas shall be identified as U.S. Condemned...

  4. 9 CFR 309.9 - Swine erysipelas.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Swine erysipelas. 309.9 Section 309.9... CERTIFICATION ANTE-MORTEM INSPECTION § 309.9 Swine erysipelas. All hogs plainly showing on ante-mortem inspection that they are affected with acute swine erysipelas shall be identified as U.S. Condemned...

  5. 9 CFR 309.9 - Swine erysipelas.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Swine erysipelas. 309.9 Section 309.9... CERTIFICATION ANTE-MORTEM INSPECTION § 309.9 Swine erysipelas. All hogs plainly showing on ante-mortem inspection that they are affected with acute swine erysipelas shall be identified as U.S. Condemned...

  6. 9 CFR 311.5 - Swine erysipelas.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Swine erysipelas. 311.5 Section 311.5... CERTIFICATION DISPOSAL OF DISEASED OR OTHERWISE ADULTERATED CARCASSES AND PARTS § 311.5 Swine erysipelas. Carcasses affected with swine erysipelas which is acute or generalized, or which show systemic change,...

  7. 9 CFR 309.9 - Swine erysipelas.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Swine erysipelas. 309.9 Section 309.9... CERTIFICATION ANTE-MORTEM INSPECTION § 309.9 Swine erysipelas. All hogs plainly showing on ante-mortem inspection that they are affected with acute swine erysipelas shall be identified as U.S. Condemned...

  8. Scrapie in swine: a diagnostic challenge

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A naturally occurring prion disease has not been recognized in swine, but the agent of bovine spongiform encephalopathy does transmit to swine by experimental routes. Swine are thought to have a robust species barrier when exposed to the naturally occurring prion diseases of other species, but the s...

  9. 75 FR 16641 - Swine Contract Library

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-02

    ... and Stockyards Administration 9 CFR Part 206 RIN 0580-AB06 Swine Contract Library AGENCY: Grain... (1999 Act) by establishing the Swine Contract Library (SCL). The statutory authority for the library... II of the P&S Act to include Subtitle B--Swine Packer Marketing Contracts. The 1999 Act mandated...

  10. 9 CFR 91.9 - Swine.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... paragraph (c) of this section, all breeding swine shall be tested for and show negative test results to... Uniform Methods and Rules, chapter 2, part II, G, 1, 2, and 3. (c) Breeding swine exported to a country that does not require breeding swine from the United States to be tested for brucellosis need...

  11. 9 CFR 91.9 - Swine.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... paragraph (c) of this section, all breeding swine shall be tested for and show negative test results to... Uniform Methods and Rules, chapter 2, part II, G, 1, 2, and 3. (c) Breeding swine exported to a country that does not require breeding swine from the United States to be tested for brucellosis need...

  12. A Mid-Layer Model for Human Reliability Analysis: Understanding the Cognitive Causes of Human Failure Events

    SciTech Connect

    Stacey M. L. Hendrickson; April M. Whaley; Ronald L. Boring; James Y. H. Chang; Song-Hua Shen; Ali Mosleh; Johanna H. Oxstrand; John A. Forester; Dana L. Kelly; Erasmia L. Lois

    2010-06-01

    The Office of Nuclear Regulatory Research (RES) is sponsoring work in response to a Staff Requirements Memorandum (SRM) directing an effort to establish a single human reliability analysis (HRA) method for the agency or guidance for the use of multiple methods. As part of this effort an attempt to develop a comprehensive HRA qualitative approach is being pursued. This paper presents a draft of the method’s middle layer, a part of the qualitative analysis phase that links failure mechanisms to performance shaping factors. Starting with a Crew Response Tree (CRT) that has identified human failure events, analysts identify potential failure mechanisms using the mid-layer model. The mid-layer model presented in this paper traces the identification of the failure mechanisms using the Information-Diagnosis/Decision-Action (IDA) model and cognitive models from the psychological literature. Each failure mechanism is grouped according to a phase of IDA. Under each phase of IDA, the cognitive models help identify the relevant performance shaping factors for the failure mechanism. The use of IDA and cognitive models can be traced through fault trees, which provide a detailed complement to the CRT.

  13. A mid-layer model for human reliability analysis : understanding the cognitive causes of human failure events.

    SciTech Connect

    Shen, Song-Hua; Chang, James Y. H.; Boring,Ronald L.; Whaley, April M.; Lois, Erasmia; Hendrickson, Stacey M. Langfitt; Oxstrand, Johanna H.; Forester, John Alan; Kelly, Dana L.; Mosleh, Ali

    2010-03-01

    The Office of Nuclear Regulatory Research (RES) at the US Nuclear Regulatory Commission (USNRC) is sponsoring work in response to a Staff Requirements Memorandum (SRM) directing an effort to establish a single human reliability analysis (HRA) method for the agency or guidance for the use of multiple methods. As part of this effort an attempt to develop a comprehensive HRA qualitative approach is being pursued. This paper presents a draft of the method's middle layer, a part of the qualitative analysis phase that links failure mechanisms to performance shaping factors. Starting with a Crew Response Tree (CRT) that has identified human failure events, analysts identify potential failure mechanisms using the mid-layer model. The mid-layer model presented in this paper traces the identification of the failure mechanisms using the Information-Diagnosis/Decision-Action (IDA) model and cognitive models from the psychological literature. Each failure mechanism is grouped according to a phase of IDA. Under each phase of IDA, the cognitive models help identify the relevant performance shaping factors for the failure mechanism. The use of IDA and cognitive models can be traced through fault trees, which provide a detailed complement to the CRT.

  14. Kernel Smoothed Profile Likelihood Estimation in the Accelerated Failure Time Frailty Model for Clustered Survival Data

    PubMed Central

    Liu, Bo; Lu, Wenbin; Zhang, Jiajia

    2013-01-01

    Summary Clustered survival data frequently arise in biomedical applications, where event times of interest are clustered into groups such as families. In this article we consider an accelerated failure time frailty model for clustered survival data and develop nonparametric maximum likelihood estimation for it via a kernel smoother aided EM algorithm. We show that the proposed estimator for the regression coefficients is consistent, asymptotically normal and semiparametric efficient when the kernel bandwidth is properly chosen. An EM-aided numerical differentiation method is derived for estimating its variance. Simulation studies evaluate the finite sample performance of the estimator, and it is applied to the Diabetic Retinopathy data set. PMID:24443587

  15. A model for predicting high-temperature fatigue failure of a W/Cu composite

    NASA Technical Reports Server (NTRS)

    Verrilli, M. J.; Kim, Y.-S.; Gabb, T. P.

    1991-01-01

    The material studied, a tungsten-fiber-reinforced, copper-matrix composite, is a candidate material for rocket nozzle liner applications. It was shown that at high temperatures, fatigue cracks initiate and propagate inside the copper matrix through a process of initiation, growth, and coalescence of grain boundary cavities. The ductile tungsten fibers neck and rupture locally after the surrounding matrix fails, and complete failure of the composite then ensues. A simple fatigue life prediction model is presented for the tungsten/copper composite system.

  16. Modeling the Failure of Magmatic Foams and Application to Infrasonic Signals at Stromboli Volcano, Italy

    NASA Astrophysics Data System (ADS)

    Baker, D. R.; O'Shaughnessy, C. A.; Brun, F.; Mancini, L.; Fife, J.

    2014-12-01

    The failure of magmatic foams appears to be a fundamental eruption process at open-conduit, basaltic volcanoes. We applied the fiber bundle model using global load sharing to model the failure of magmatic foams. The fiber strengths in the model were taken from bubble wall widths measured in four computer-simulated foams and by X-ray tomographic microscopy in three foams produced in the laboratory by heating hydrated basaltic glasses at 1 atm. to 1200 °C. The strengths of the modeled foams were calibrated based upon the correlation of the strength of one foam with published experimental data. The fiber bundle model successfully reproduced measured tensile strengths of porous volcanic rocks studied by other researchers and confirms published findings of the primary importance of foam porosity, as well as the secondary importance of structural details that affect the number and size of bubble walls and permeability. The success of the fiber bundle model in reproducing foam strengths encouraged us to compare its predictions with infrasonic measurements associated with bubbles at Stromboli (Italy). We found that within uncertainty the power-law exponents of the infrasonic energies and of the fiber bundle model energies are in agreement. They both show a cross-over from an exponent of 5/2 associated with the bursting of small bubbles in the infrasonic measurements to an exponent of 3/2 for normal Strombolian eruptions associated with infrasonic signals from meter-scale bubbles. The infrasonic signals for major explosions and a paroxysmal eruption at Stromboli fall near the extrapolation of the power law defined by the low-amplitude, bubble bursting events. The measurement of small-amplitude infrasonic events at Stromboli thus appear useful in predicting the recurrence interval of paroxysmal eruptions at this volcano and may also provide a tool that uses common, small-amplitude infrasonic events to constrain the frequency of larger eruptions at other volcanoes.

  17. A porcine model of hypertensive cardiomyopathy: implications for heart failure with preserved ejection fraction.

    PubMed

    Schwarzl, Michael; Hamdani, Nazha; Seiler, Sebastian; Alogna, Alessio; Manninger, Martin; Reilly, Svetlana; Zirngast, Birgit; Kirsch, Alexander; Steendijk, Paul; Verderber, Jochen; Zweiker, David; Eller, Philipp; Höfler, Gerald; Schauer, Silvia; Eller, Kathrin; Maechler, Heinrich; Pieske, Burkert M; Linke, Wolfgang A; Casadei, Barbara; Post, Heiner

    2015-11-01

    Heart failure with preserved ejection fraction (HFPEF) evolves with the accumulation of risk factors. Relevant animal models to identify potential therapeutic targets and to test novel therapies for HFPEF are missing. We induced hypertension and hyperlipidemia in landrace pigs (n = 8) by deoxycorticosteroneacetate (DOCA, 100 mg/kg, 90-day-release subcutaneous depot) and a Western diet (WD) containing high amounts of salt, fat, cholesterol, and sugar for 12 wk. Compared with weight-matched controls (n = 8), DOCA/WD-treated pigs showed left ventricular (LV) concentric hypertrophy and left atrial dilatation in the absence of significant changes in LV ejection fraction or symptoms of heart failure at rest. The LV end-diastolic pressure-volume relationship was markedly shifted leftward. During simultaneous right atrial pacing and dobutamine infusion, cardiac output reserve and LV peak inflow velocities were lower in DOCA/WD-treated pigs at higher LV end-diastolic pressures. In LV biopsies, we observed myocyte hypertrophy, a shift toward the stiffer titin isoform N2B, and reduced total titin phosphorylation. LV superoxide production was increased, in part attributable to nitric oxide synthase (NOS) uncoupling, whereas AKT and NOS isoform expression and phosphorylation were unchanged. In conclusion, we developed a large-animal model in which loss of LV capacitance was associated with a titin isoform shift and dysfunctional NOS, in the presence of preserved LV ejection fraction. Our findings identify potential targets for the treatment of HFPEF in a relevant large-animal model.

  18. Chronic arteriovenous shunt: evaluation of a model for heart failure in rat.

    PubMed

    Flaim, S F; Minteer, W J; Nellis, S H; Clark, D P

    1979-05-01

    A model for high output heart failure (HCO) was developed in male, Sprague-Dawley rats using an abdominal aortocaval shunt equal to 50% of total cardiac output (CO) with 2 mo of postsurgical recovery. The model was evaluated by analysis of hemodynamics, peripheral blood flows (BF) (radioactive microspheres), and plasma catecholamine levels as well as mass and fluid content of organs. In HCO, CO and left ventricular end-diastolic pressure were increased with significant left and right ventricular hypertrophy. Mean blood pressure (BP) was unchanged, but pulse BP was increased in HCO. BF to skeletal muscle, cutaneous, and some splanchnic regions was reduced to HCO, whereas BF to the cerebral, coronary, and renal beds was protected. Plasma epinephrine and norepinephrine levels were significantly elevated in HCO suggesting enhanced sympathetic as well as adrenal catecholamine release. Tissue analysis indicated altered circulatory status secondary to HCO in liver, kidney, spleen, and lung. The results indicate that this model will be a relevant tool for studies of the circulatory effects of heart failure.

  19. Pathogenesis and Transmission of Feral Swine Pseudorabies Virus Isolates in Domestic Pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudorabies is one of the oldest described swine diseases recognized as reproductive failure, and respiratory and central nervous system disease. It is caused by pseudorabies virus (PRV). The development of vaccines and serologic tests that allow the differentiation of vaccinated pigs from naturall...

  20. Intestinal parasites in swine in the Nordic countries: multilevel modelling of Ascaris suum infections in relation to production factors.

    PubMed

    Roepstorff, A; Nilsson, O; O'Callaghan, C J; Oksanen, A; Gjerde, B; Richter, S H; Ortenberg, E O; Christensson, D; Nansen, P; Eriksen, L; Medley, G F

    1999-11-01

    In Denmark, Finland, Iceland, Norway and Sweden, 413 sow herds were randomly selected for sampling. Faeces from pigs of 7 age groups/categories were examined for helminth eggs (11,233 individual samples), and an accompanying questionnaire was completed at each visit. In total, 1138 pigs on 230 farms were found to be positive for Ascaris suum. Consi