Science.gov

Sample records for failure swine models

  1. Engineered Swine Models of Cancer.

    PubMed

    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. 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

  3. Advances in Swine biomedical Model Genomics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This manuscript 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 pro...

  4. Advances in Swine Biomedical Model Genomics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The swine has been a major biomedical model species, for transplantation, heart disease, allergies and asthma, as well as normal neonatal development and reproductive physiology. Swine have been used extensively for studies of infectious disease processes and analyses of preventative strategies, inc...

  5. Completion of the swine genome will simplify the production of swine as a large animal biomedical model

    PubMed Central

    2012-01-01

    Background Anatomic and physiological similarities to the human make swine an excellent large animal model for human health and disease. Methods Cloning from a modified somatic cell, which can be determined in cells prior to making the animal, is the only method available for the production of targeted modifications in swine. Results Since some strains of swine are similar in size to humans, technologies that have been developed for swine can be readily adapted to humans and vice versa. Here the importance of swine as a biomedical model, current technologies to produce genetically enhanced swine, current biomedical models, and how the completion of the swine genome will promote swine as a biomedical model are discussed. Conclusions The completion of the swine genome will enhance the continued use and development of swine as models of human health, syndromes and conditions. PMID:23151353

  6. 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. PMID:23829105

  7. Failure of protection and enhanced pneumonia with a US H1N2 swine influenza virus in pigs vaccinated with an inactivated classical swine H1N1 vaccine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated two US swine influenza virus (SIV) isolates, A/Swine/Iowa/15/1930 H1N1 (IA30) and A/Swine/Minnesota/00194/2003 H1N2 (MN03), with substantial genetic variation in the HA gene and failure to cross-react in the hemagglutination inhibition (HI) assay, in an in vivo vaccination and challenge...

  8. 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.

  9. Swine model of Haemophilus ducreyi infection.

    PubMed Central

    Hobbs, M M; San Mateo, L R; Orndorff, P E; Almond, G; Kawula, T H

    1995-01-01

    Haemophilus ducreyi is a strict human pathogen that causes sexually transmitted genital ulcer disease. We infected domestic swine with H. ducreyi 35000, resulting in the development of cutaneous ulcers histologically resembling human chancroid lesions. Intraepidermal lesions progressed from pustules to ulcers containing polymorphonuclear leukocytes and were accompanied by a dermal inflammatory infiltrate containing T cells and macrophages. H. ducreyi was recovered from lesions up to 17 days after inoculation, and pigs did not develop immunity to reinfection with the challenge strain. Features of the model include inoculation through abrasions in the epidermis, ambient housing temperatures for infected pigs, the ability to deliver multiple different inocula to a single host, and the availability of monoclonal antibodies against porcine immune cells permitting immunohistochemical characterization of the host immune response to H. ducreyi infection. PMID:7622236

  10. Modeling risk of occupational zoonotic influenza infection in swine workers.

    PubMed

    Paccha, Blanca; Jones, Rachael M; Gibbs, Shawn; Kane, Michael J; Torremorell, Montserrat; Neira-Ramirez, Victor; Rabinowitz, Peter M

    2016-08-01

    Zoonotic transmission of influenza A virus (IAV) between swine and workers in swine production facilities may play a role in the emergence of novel influenza strains with pandemic potential. Guidelines to prevent transmission of influenza to swine workers have been developed but there is a need for evidence-based decision-making about protective measures such as respiratory protection. A mathematical model was applied to estimate the risk of occupational IAV exposure to swine workers by contact and airborne transmission, and to evaluate the use of respirators to reduce transmission.  The Markov model was used to simulate the transport and exposure of workers to IAV in a swine facility. A dose-response function was used to estimate the risk of infection. This approach is similar to methods previously used to estimate the risk of infection in human health care settings. This study uses concentration of virus in air from field measurements collected during outbreaks of influenza in commercial swine facilities, and analyzed by polymerase chain reaction.  It was found that spending 25 min working in a barn during an influenza outbreak in a swine herd could be sufficient to cause zoonotic infection in a worker. However, this risk estimate was sensitive to estimates of viral infectivity to humans. Wearing an excellent fitting N95 respirator reduced this risk, but with high aerosol levels the predicted risk of infection remained high under certain assumptions.  The results of this analysis indicate that under the conditions studied, swine workers are at risk of zoonotic influenza infection. The use of an N95 respirator could reduce such risk. These findings have implications for risk assessment and preventive programs targeting swine workers. The exact level of risk remains uncertain, since our model may have overestimated the viability or infectivity of IAV. Additionally, the potential for partial immunity in swine workers associated with repeated low

  11. Heart failure prognostic model.

    PubMed

    Axente, L; Sinescu, C; Bazacliu, G

    2011-05-15

    Heart failure (HF) is a common, costly, disabling and deadly syndrome. Heart failure is a progressive disease characterized by high prevalence in society, significantly reducing physical and mental health, frequent hospitalization and high mortality (50% of the patients survive up to 4 years after the diagnosis, the annual mortality varying from 5% to 75%). The purpose of this study is to develop a prognostic model with easily obtainable variables for patients with heart failure. METHODS AND RESULTS. Our lot included 101 non-consecutive hospitalized patients with heart failure diagnosis. It included 49.5% women having the average age of 71.23 years (starting from 40 up to 91 years old) and the roughly estimated period for monitoring was 35.1 months (5-65 months). Survival data were available for all patients and the median survival duration was of 44.0 months. A large number of variables (demographic, etiologic, co morbidity, clinical, echocardiograph, ECG, laboratory and medication) were evaluated. We performed a complex statistical analysis, studying: survival curve, cumulative hazard, hazard function, lifetime distribution and density function, meaning residual life time, Ln S (t) vs. t and Ln(H) t vs. Ln (t). The Cox multiple regression model was used in order to determine the major factors that allow the forecasting survival and their regression coefficients: age (0.0369), systolic blood pressure (-0.0219), potassium (0.0570), sex (-0.3124) and the acute myocardial infarction (0.2662). DISCUSSION. Our model easily incorporates obtainable variables that may be available in any hospital, accurately predicting survival of the heart failure patients and enables risk stratification in a few hours after the patients' presentation. Our model is derived from a sample of patients hospitalized in an emergency department of cardiology, some with major life-altering co morbidities. The benefit of being aware of the prognosis of these patients with high risk is extremely

  12. Heart failure prognostic model

    PubMed Central

    Axente, L; Sinescu, C; Bazacliu, G

    2011-01-01

    Heart failure (HF) is a common, costly, disabling and deadly syndrome. Heart failure is a progressive disease characterized by high prevalence in society, significantly reducing physical and mental health, frequent hospitalization and high mortality (50% of the patients survive up to 4 years after the diagnosis, the annual mortality varying from 5% to 75%). The purpose of this study is to develop a prognostic model with easily obtainable variables for patients with heart failure. Methods and Results. Our lot included 101 non–consecutive hospitalized patients with heart failure diagnosis. It included 49,5% women having the average age of 71.23 years (starting from 40 up to 91 years old) and the roughly estimated period for monitoring was 35.1 months (5–65 months). Survival data were available for all patients and the median survival duration was of 44.0 months. A large number of variables (demographic, etiologic, co morbidity, clinical, echocardiograph, ECG, laboratory and medication) were evaluated. We performed a complex statistical analysis, studying: survival curve, cumulative hazard, hazard function, lifetime distribution and density function, meaning residual life time, Ln S (t) vs. t and Ln(H) t vs. Ln (t). The Cox multiple regression model was used in order to determine the major factors that allow the forecasting survival and their regression coefficients: age (0.0369), systolic blood pressure (–0.0219), potassium (0.0570), sex (–0.3124) and the acute myocardial infarction (0.2662). Discussion. Our model easily incorporates obtainable variables that may be available in any hospital, accurately predicting survival of the heart failure patients and enables risk stratification in a few hours after the patients' presentation. Our model is derived from a sample of patients hospitalized in an emergency department of cardiology, some with major life–altering co morbidities. The benefit of being aware of the prognosis of these patients with high risk is

  13. Swine Hybrid Aneurysm Model for Endovascular Surgery Training

    PubMed Central

    Namba, K.; Mashio, K.; Kawamura, Y.; Higaki, A.; Nemoto, S.

    2013-01-01

    Summary The aim of this study was to develop a technically simple swine aneurysm-training model by inserting a silicone aneurysm circuit in the cervical vessels. A silicone aneurysm circuit was created by designing multiple aneurysms in size and configuration on a silicone vessel. Five swine underwent surgical implantation of this circuit in the cervical vessels: one end in the common carotid artery and the other in the external jugular vein. Using this model, an aneurysm coiling procedure was simulated under fluoroscopic guidance, roadmapping and digital subtraction angiography. Creating an aneurysm model for training purposes by this method was technically simple and enabled the formation of a wide variety of aneurysms in a single procedure. The quality of the model was uniform and the model was reproducible. Coiling training using this model resembled a realistic clinical situation. The swine hybrid aneurysm-training model was advantageous from the standpoint of technical simplicity in the creation and variety of aneurysms it provided. The swine hybrid aneurysm model may be an additional option for aneurysm coiling training. PMID:23693037

  14. Swine hybrid aneurysm model for endovascular surgery training.

    PubMed

    Namba, K; Mashio, K; Kawamura, Y; Higaki, A; Nemoto, S

    2013-06-01

    The aim of this study was to develop a technically simple swine aneurysm-training model by inserting a silicone aneurysm circuit in the cervical vessels. A silicone aneurysm circuit was created by designing multiple aneurysms in size and configuration on a silicone vessel. Five swine underwent surgical implantation of this circuit in the cervical vessels: one end in the common carotid artery and the other in the external jugular vein. Using this model, an aneurysm coiling procedure was simulated under fluoroscopic guidance, roadmapping and digital subtraction angiography. Creating an aneurysm model for training purposes by this method was technically simple and enabled the formation of a wide variety of aneurysms in a single procedure. The quality of the model was uniform and the model was reproducible. Coiling training using this model resembled a realistic clinical situation. The swine hybrid aneurysm-training model was advantageous from the standpoint of technical simplicity in the creation and variety of aneurysms it provided. The swine hybrid aneurysm model may be an additional option for aneurysm coiling training. PMID:23693037

  15. 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.…

  16. DNA Vaccines: Experiences in the Swine Model.

    PubMed

    Accensi, Francesc; Rodríguez, Fernando; Monteagudo, Paula L

    2016-01-01

    DNA vaccination is one of the most fascinating vaccine-strategies currently in development. Two of the main advantages of DNA immunization rely on its simplicity and flexibility, being ideal to dissect both the immune mechanisms and the antigens involved in protection against a given pathogen. Here, we describe several strategies used to enhance the immune responses induced and the protection afforded by experimental DNA vaccines tested in swine and provide with very basic protocol describing the generation and in vivo application of a prototypic DNA vaccine. Only time will tell the last word regarding the definitive implementation of DNA vaccination in the field. PMID:26458829

  17. 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.

  18. 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.

  19. 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.

  20. A swine dysentery model for evaluation of drug prophylaxis: efficacy of various drugs in the control of swine dysentery.

    PubMed

    Raynaud, J P; Brunault, G; Patterson, E B

    1981-01-01

    A swine dysentery (SD) model that produces consistent, homogeneous, and severe SD was used in 2 experiments to compare the prophylactic effectiveness of 5 commercially available swine feed additive products. Under the conditions of these studies, carbadox and carbadox + sulfamethazine proved to be the most effective agents in preventing SD during the infection + medication and postmedication periods. Olaquindox was effective in preventing SD in the infection + medication period; however, SD recurrence was high during the postmedication period. Nithiamide and chlortetracycline + sulfamethazine + penicillin were least effective in preventing SD during the infection + medication and postmedication periods. PMID:7224318

  1. 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. PMID:26814353

  2. 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.

  3. Modeling Classical Swine Fever Outbreak-Related Outcomes.

    PubMed

    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 could

  4. 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

  5. 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

  6. Investigating the metabolic syndrome: Contributions of swine models

    PubMed Central

    Zhang, Xin; Lerman, Lilach O.

    2016-01-01

    The metabolic syndrome (MetS), a cluster of dyslipidemia, hypertension, and diabetes, and an important contributor to cardiovascular morbidity and mortality, occurs in nearly 35% of adults and 50% of the aging population in the United States. However, the underlying mechanisms by which MetS orchestrates and amplifies cardiovascular events remain elusive. Furthermore, traditional therapeutic strategies addressing lifestyle modifications and individual components of MetS are often unsuccessful in decreasing morbidity due to MetS. The availability of an adequate experimental platform that mimics the complexity of MetS may allow development of novel management techniques. Swine models, including domestic pigs and minipigs, have made important contributions to our understanding of many aspects of MetS. Given their similarity to human anatomy and physiology, those models may have significant predictive power for elucidating the pathophysiology of MetS in a manner applicable to humans. Moreover, experimental maneuvers and drugs can be tested in these pre-clinical models before application in patients with MetS. This review highlights the utility of the pig as an animal model for metabolic disorders, which may play a crucial role in novel drug development to optimize management of MetS. PMID:26933085

  7. 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. PMID:25140745

  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. Swine models in the design of more effective medical countermeasures against organophosphorus poisoning.

    PubMed

    Dorandeu, F; Mikler, J R; Thiermann, H; Tenn, C; Davidson, C; Sawyer, T W; Lallement, G; Worek, F

    2007-04-20

    Although the three most commonly used large mammal species in the safety assessment of drugs remain the dog, the macaque and the marmoset, swine, especially minipigs, have also been widely used over the years in many toxicological studies. Swine present a number of interesting biological and physiological characteristics. Similarities in skin properties with humans have led to extensive in vitro and in vivo studies. There is a specific interest in cardiovascular research, as well as in anaesthesiology and critical care medicine due to common features of swine and human physiology. Although knowledge of swine brain structure and functions remains incomplete, data does exist. The multiple blood sampling that is necessary in pharmacokinetic and toxicokinetic studies are possible, as well as multiparametric monitoring and interventions with equipment used in human clinical settings. Practicality (handling), scientific (stress reduction) and ethical (invasive monitoring) reasons have led research teams to incorporate anaesthesia into their paradigms which makes the analysis of data increasingly difficult. Although not substantiated by scientific data, the swine appears to have an intermediate position in the scale of public perception between non-human primates and animals commonly referred to as pets (i.e. dogs and cats) and rodents. The benefits of the swine model justify the use of these animals in the design of more effective medical countermeasures against known chemical warfare agents (nerve agents, vesicants and lung damaging agents). Exposure to organophosphorus (OP) pesticides represents a severe health issue in developing countries, while OP intoxication with the more lethal military nerve agents is not only of military concern but also a terrorist threat. Tailoring therapeutic regimens to the reality of OP poisoning is of the utmost importance when little experimental data and sparse human clinical data are available in the decision making process. We will

  10. Swine as a model for influenza A virus infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Influenza A viruses (IAV) infect a variety of hosts, including humans, swine, and various avian species. The annual influenza disease burden in the human population remains significant even with current vaccine usage and much about the pathogenesis and transmission of influenza viruses in human rema...

  11. 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.

  12. Model the Deformation and Failure of Solids

    Energy Science and Technology Software Center (ESTSC)

    2001-10-19

    EMU models the deformation and failure of solids based on a reformulated theory of continuum mechanics known as the Peridynamic model. This approach allows dynamic fracture and other failure mechanisms to be simulated with a minimum of mesh effeces and without a need for supplementary kinetic relations for crack growth. Penetration by a rigid projectile is also included in the code.

  13. 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.

  14. 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. PMID:19802552

  15. 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.

  16. 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

  17. Miniature Swine as a Clinically Relevant Model of Graft-Versus-Host Disease

    PubMed Central

    Duran-Struuck, Raimon; Huang, Christene A; Orf, Katherine; Bronson, Roderick T; Sachs, David H; Spitzer, Thomas R

    2015-01-01

    Miniature swine provide a preclinical model of hematopoietic cell transplantation (HCT) for studies of graft-versus-host disease. HCT between MHC-matched or ‑mismatched pigs can be performed to mimic clinical scenarios with outcomes that closely resemble those observed in human HCT recipients. With myeloablative conditioning, HCT across MHC barriers is typically fatal, with pigs developing severe (grade III or IV) GVHD involving the gastrointestinal tract, liver, and skin. Unlike rodent models, miniature swine provide an opportunity to perform extended longitudinal studies on individual animals, because multiple tissue biopsies can be harvested without the need for euthanasia. In addition, we have developed a swine GVHD scoring system that parallels that used in the human clinical setting. Given the similarities of GVHD in pigs and humans, we hope that the use of this scoring system facilitates clinical and scientific discourse between the laboratory and the clinic. We anticipate that results of swine studies will support the development of new strategies to improve the identification and treatment of GVHD in clinical HCT scenarios. PMID:26473348

  18. Physical modelling of failure in composites.

    PubMed

    Talreja, Ramesh

    2016-07-13

    Structural integrity of composite materials is governed by failure mechanisms that initiate at the scale of the microstructure. The local stress fields evolve with the progression of the failure mechanisms. Within the full span from initiation to criticality of the failure mechanisms, the governing length scales in a fibre-reinforced composite change from the fibre size to the characteristic fibre-architecture sizes, and eventually to a structural size, depending on the composite configuration and structural geometry as well as the imposed loading environment. Thus, a physical modelling of failure in composites must necessarily be of multi-scale nature, although not always with the same hierarchy for each failure mode. With this background, the paper examines the currently available main composite failure theories to assess their ability to capture the essential features of failure. A case is made for an alternative in the form of physical modelling and its skeleton is constructed based on physical observations and systematic analysis of the basic failure modes and associated stress fields and energy balances. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'. PMID:27242307

  19. STATISTICAL MODELS FOR WATER MAIN FAILURES

    EPA Science Inventory

    A detailed statistical analysis of pipe break records from New Haven, Connecticut, and Cincinnati, Ohio, water distribution systems focussed on deriving predictive models for pipe failure probabilities at the individual pipe level. The statistical methodology of the proportional ...

  20. Quantitative Proteomics Identifies Host Factors Modulated during Acute Hepatitis E Virus Infection in the Swine Model

    PubMed Central

    Rogée, Sophie; Le Gall, Morgane; Chafey, Philippe; Bouquet, Jérôme; Cordonnier, Nathalie; Frederici, Christian

    2014-01-01

    ABSTRACT Hepatitis E virus (HEV) causes acute enterically transmitted hepatitis. In industrialized countries, it is a zoonotic disease, with swine being the major reservoir of human HEV contamination. The occurrence and severity of the disease are variable, with clinical symptoms ranging from asymptomatic to self-limiting acute hepatitis, chronic infection, or fulminant hepatitis. In the absence of a robust cell culture system or small-animal models, the HEV life cycle and pathological process remain unclear. To characterize HEV pathogenesis and virulence mechanisms, a quantitative proteomic analysis was carried out to identify cellular factors and pathways modulated during acute infection of swine. Three groups of pigs were inoculated with three different strains of swine HEV to evaluate the possible role of viral determinants in pathogenesis. Liver samples were analyzed by a differential proteomic approach, two-dimensional difference in gel electrophoresis, and 61 modulated proteins were identified by mass spectroscopy. The results obtained show that the three HEV strains replicate similarly in swine and that they modulate several cellular pathways, suggesting that HEV impairs several cellular processes, which can account for the various types of disease expression. Several proteins, such as heterogeneous nuclear ribonucleoprotein K, apolipoprotein E, and prohibitin, known to be involved in other viral life cycles, were upregulated in HEV-infected livers. Some differences were observed between the three strains, suggesting that HEV's genetic variability may induce variations in pathogenesis. This comparative analysis of the liver proteome modulated during infection with three different strains of HEV genotype 3 provides an important basis for further investigations on the factors involved in HEV replication and the mechanism of HEV pathogenesis. IMPORTANCE Hepatitis E virus (HEV) is responsible for acute hepatitis, with clinical symptoms ranging from asymptomatic

  1. Quantitative assessment of partial vascular occlusions in a swine pedicle flap model using spatial frequency domain imaging

    PubMed Central

    Ponticorvo, Adrien; Taydas, Eren; Mazhar, Amaan; Scholz, Thomas; Kim, Hak-Su; Rimler, Jonathan; Evans, Gregory R. D.; Cuccia, David J.; Durkin, Anthony J.

    2013-01-01

    The use of tissue transfer flaps has become a common and effective technique for reconstructing or replacing damaged tissue. While the overall failure rate associated with these procedures is relatively low (5-10%), the failure rate of tissue flaps that require additional surgery is significantly higher (40-60%). The reason for this is largely due to the absence of a technique for objectively assessing tissue health after surgery. Here we have investigated spatial frequency domain imaging (SFDI) as a potential tool to do this. By projecting wide-field patterned illumination at multiple wavelengths onto a tissue surface, SFDI is able to quantify absolute concentrations of oxygenated and deoxygenated hemoglobin over a large field of view. We have assessed the sensitivity of SFDI in a swine pedicle flap model by using a controlled vascular occlusion system that reduced blood flow by 25%, 50%, 75%, or 100% of the baseline values in either the vein or artery. SFDI was able to detect significant changes for oxygenated hemoglobin, deoxygenated hemoglobin, or tissue oxygen saturation in partial arterial occlusions of at least 50% and partial venous occlusions of at least 25%. This shows SFDI is sensitive enough to quantify changes in the tissue hemoglobin state during partial occlusions and thus has the potential to be a powerful tool for the early prediction of tissue flap failure. PMID:23412357

  2. 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

  3. 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. PMID:26635868

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

    PubMed Central

    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. PMID:26635868

  5. Modelling early failures in Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Navard, Sharon E.

    1993-01-01

    A major problem encountered in planning for Space Station Freedom is the amount of maintenance that will be required. To predict the failure rates of components and systems aboard Space Station Freedom, the logical approach is to use data obtained from previously flown spacecraft. In order to determine the mechanisms that are driving the failures, models can be proposed, and then checked to see if they adequately fit the observed failure data obtained from a large variety of satellites. For this particular study, failure data and truncation times were available for satellites launched between 1976 and 1984; no data past 1984 was available. The study was limited to electrical subsystems and assemblies, which were studied to determine if they followed a model resulting from a mixture of exponential distributions.

  6. Development and application of a simulation model for the thermophilic oxic process for treating swine waste.

    PubMed

    Jeon, Kyoungho; Nakano, Kazunori; Nishimura, Osamu

    2011-01-01

    The thermophilic oxic process (TOP) is a composting process that enables simultaneous complete decomposition and evaporation of organic waste under high temperature conditions supported by well-balanced calorific value control. To develop the simulation model for TOP, three-dimensional relationships among decomposition rate constant, temperature (20-70 °C) and moisture content (30-70%) were determined for swine waste and cooking oil based on the oxygen consumption rate during a thermophilic oxic decomposition reaction. The decomposition rate of swine waste and cooking oil under various moisture contents was described by the Arrhenius equation. The optimal temperature and moisture content were 60 °C and 60% for swine waste and 60 °C and 50% for cooking oil, respectively. The simulation model for TOP was constructed on the basis of the carbon, heat, and moisture balance. The validation of the simulation model was examined by comparing the measured temperature in the TOP reactor to that estimated by the simulation. The simulation model was proven by comparing experimental and calculated values. The relationship between the injection calorific value and the process mechanism of TOP was interpreted by the simulation model. On the basis of their relationship during TOP, the appropriate process conditions were discussed. PMID:20934200

  7. Use of AERMOD to Determine a Hydrogen Sulfide Emission Factor for Swine Operations by Inverse Modeling

    PubMed Central

    O’Shaughnessy, Patrick T.; Altmaier, Ralph

    2011-01-01

    This study was conducted to determine both optimal settings applied to the plume dispersion model, AERMOD, and a scalable emission factor for accurately determining the spatial distribution of hydrogen sulfide concentrations in the vicinity of swine concentrated animal feeding operations (CAFOs). These operations emit hydrogen sulfide from both housing structures and waste lagoons. With ambient measurements made at 4 stations within 1 km of large swine CAFOs in Iowa, an inverse-modeling approach applied to AERMOD was used to determine hydrogen sulfide emission rates. CAFO buildings were treated as volume sources whereas nearby lagoons were modeled as area sources. The robust highest concentration (RHC), calculated for both measured and modeled concentrations, was used as the metric for adjusting the emission rate until the ratio of the two RHC levels was unity. Utilizing this approach, an average emission flux rate of 0.57 µg/m2-s was determined for swine CAFO lagoons. Using the average total animal weight (kg) of each CAFO, an average emission factor of 6.06 × 10−7 µg/yr-m2-kg was calculated. From studies that measured either building or lagoon emission flux rates, building fluxes, on a floor area basis, were considered equal to lagoon flux rates. The emission factor was applied to all CAFOs surrounding the original 4 sites and surrounding an additional 6 sites in Iowa, producing an average modeled-to-measured RHC ratio of 1.24. When the emission factor was applied to AERMOD to simulate the spatial distribution of hydrogen sulfide around a hypothetical large swine CAFO (1M kg), concentrations 0.5 km from the CAFO were 35 ppb and dropped to 2 ppb within 6 km of the CAFO. These values compare to a level of 30 ppb that has been determined by the State of Iowa as a threshold level for ambient hydrogen sulfide levels. PMID:21804761

  8. Use of AERMOD to Determine a Hydrogen Sulfide Emission Factor for Swine Operations by Inverse Modeling.

    PubMed

    O'Shaughnessy, Patrick T; Altmaier, Ralph

    2011-08-01

    This study was conducted to determine both optimal settings applied to the plume dispersion model, AERMOD, and a scalable emission factor for accurately determining the spatial distribution of hydrogen sulfide concentrations in the vicinity of swine concentrated animal feeding operations (CAFOs). These operations emit hydrogen sulfide from both housing structures and waste lagoons. With ambient measurements made at 4 stations within 1 km of large swine CAFOs in Iowa, an inverse-modeling approach applied to AERMOD was used to determine hydrogen sulfide emission rates. CAFO buildings were treated as volume sources whereas nearby lagoons were modeled as area sources. The robust highest concentration (RHC), calculated for both measured and modeled concentrations, was used as the metric for adjusting the emission rate until the ratio of the two RHC levels was unity. Utilizing this approach, an average emission flux rate of 0.57 µg/m(2)-s was determined for swine CAFO lagoons. Using the average total animal weight (kg) of each CAFO, an average emission factor of 6.06 × 10(-7) µg/yr-m(2)-kg was calculated. From studies that measured either building or lagoon emission flux rates, building fluxes, on a floor area basis, were considered equal to lagoon flux rates. The emission factor was applied to all CAFOs surrounding the original 4 sites and surrounding an additional 6 sites in Iowa, producing an average modeled-to-measured RHC ratio of 1.24. When the emission factor was applied to AERMOD to simulate the spatial distribution of hydrogen sulfide around a hypothetical large swine CAFO (1M kg), concentrations 0.5 km from the CAFO were 35 ppb and dropped to 2 ppb within 6 km of the CAFO. These values compare to a level of 30 ppb that has been determined by the State of Iowa as a threshold level for ambient hydrogen sulfide levels. PMID:21804761

  9. Use of AERMOD to determine a hydrogen sulfide emission factor for swine operations by inverse modeling

    NASA Astrophysics Data System (ADS)

    O'Shaughnessy, Patrick T.; Altmaier, Ralph

    2011-09-01

    This study was conducted to determine both optimal settings applied to the plume dispersion model, AERMOD, and a scalable emission factor for accurately determining the spatial distribution of hydrogen sulfide concentrations in the vicinity of swine concentrated animal feeding operations (CAFOs). These operations emit hydrogen sulfide from both housing structures and waste lagoons. With ambient measurements made at 4 stations within 1 km of large swine CAFOs in Iowa, an inverse-modeling approach applied to AERMOD was used to determine hydrogen sulfide emission rates. CAFO buildings were treated as volume sources whereas nearby lagoons were modeled as area sources. The robust highest concentration (RHC), calculated for both measured and modeled concentrations, was used as the metric for adjusting the emission rate until the ratio of the two RHC levels was unity. Utilizing this approach, an average emission flux rate of 0.57 μg m -2 s -1 was determined for swine CAFO lagoons. Using the average total animal weight (kg) of each CAFO, an average emission factor of 6.06 × 10 -7 μg yr -1 m -2 kg -1 was calculated. From studies that measured either building or lagoon emission flux rates, building fluxes, on a floor area basis, were considered equal to lagoon flux rates. The emission factor was applied to all CAFOs surrounding the original 4 sites and surrounding an additional 6 sites in Iowa, producing an average modeled-to-measured RHC ratio of 1.24. When the emission factor was applied to AERMOD to simulate the spatial distribution of hydrogen sulfide around a hypothetical large swine CAFO (1 M kg), concentrations within 0.5 km from the CAFO exceeded 25 ppb and dropped to 2 ppb within 6 km of the CAFO. These values compare to a level of 30 ppb that has been determined by the State of Iowa as a threshold level for ambient hydrogen sulfide levels.

  10. A swine model of infarct-related reentrant ventricular tachycardia: Electroanatomic, magnetic resonance, and histopathological characterization

    PubMed Central

    Tschabrunn, Cory M.; Roujol, Sébastien; Nezafat, Reza; Faulkner-Jones, Beverly; Buxton, Alfred E.; Josephson, Mark E.; Anter, Elad

    2016-01-01

    BACKGROUND Human ventricular tachycardia (VT) after myocardial infarction usually occurs because of subendocardial reentrant circuits originating in scar tissue that borders surviving myocardial bundles. Several preclinical large animal models have been used to further study postinfarct reentrant VT, but with varied experimental methodologies and limited evaluation of the underlying substrate or induced arrhythmia mechanism. OBJECTIVE We aimed to develop and characterize a swine model of scar-related reentrant VT. METHODS Thirty-five Yorkshire swine underwent 180-minute occlusion of the left anterior descending coronary artery. Thirty-one animals (89%) survived the 6–8-week survival period. These animals underwent cardiac magnetic resonance imaging followed by electrophysiology study, detailed electroanatomic mapping, and histopathological analysis. RESULTS Left ventricular (LV) ejection fraction measured using CMR imaging was 36% ± 6.6% with anteroseptal wall motion abnormality and late gadolinium enhancement across 12.5% ± 4.1% of the LV surface area. Low voltage measured using endocardial electroanatomic mapping encompassed 11.1% ± 3.5% of the LV surface area (bipolar voltage ≤1.5 mV) with anterior, anteroseptal, and anterolateral involvement. Reentrant circuits mapped were largely determined by functional rather than fix anatomical barriers, consistent with “pseudo-block” due to anisotropic conduction. Sustained monomorphic VT was induced in 28 of 31 swine (90%) (67 VTs; 2.4 ± 1.1; range 1–4) and characterized as reentry. VT circuits were subendocardial, with an arrhythmogenic substrate characterized by transmural anterior scar with varying degrees of fibrosis and myocardial fiber disarray on the septal and lateral borders. CONCLUSION This is a well-characterized swine model of scar-related subendocardial reentrant VT. This model can serve as the basis for further investigation in the physiology and therapeutics of humanlike postinfarction

  11. Parameter Values for Epidemiological Models of Foot-and-Mouth Disease in Swine

    PubMed Central

    Kinsley, Amy C.; Patterson, Gilbert; VanderWaal, Kimberly L.; Craft, Meggan E.; Perez, Andres M.

    2016-01-01

    In the event of a foot-and-mouth disease (FMD) incursion, response strategies are required to control, contain, and eradicate the pathogen as efficiently as possible. Infectious disease simulation models are widely used tools that mimic disease dispersion in a population and that can be useful in the design and support of prevention and mitigation activities. However, there are often gaps in evidence-based research to supply models with quantities that are necessary to accurately reflect the system of interest. The objective of this study was to quantify values associated with the duration of the stages of FMD infection (latent period, subclinical period, incubation period, and duration of infection), probability of transmission (within-herd and between-herd via spatial spread), and diagnosis of a vesicular disease within a herd using a meta-analysis of the peer-reviewed literature and expert opinion. The latent period ranged from 1 to 7 days and incubation period ranged from 1 to 9 days; both were influenced by strain. In contrast, the subclinical period ranged from 0 to 6 days and was influenced by sampling method only. The duration of infection ranged from 1 to 10 days. The probability of spatial spread between an infected and fully susceptible swine farm was estimated as greatest within 5 km of the infected farm, highlighting the importance of possible long-range transmission through the movement of infected animals. Finally, while most swine practitioners are confident in their ability to detect a vesicular disease in an average sized swine herd, a small proportion expect that up to half of the herd would need to show clinical signs before detection via passive surveillance would occur. The results of this study will be useful in within- and between-herd simulation models to develop efficient response strategies in the event an FMD in swine populations of disease-free countries or regions. PMID:27314002

  12. Iodoacetic acid, but not sodium iodate, creates an inducible swine model of photoreceptor damage.

    PubMed

    Noel, Jennifer M; Fernandez de Castro, Juan P; Demarco, Paul J; Franco, Luisa M; Wang, Wei; Vukmanic, Eric V; Peng, Xiaoyan; Sandell, Julie H; Scott, Patrick A; Kaplan, Henry J; McCall, Maureen A

    2012-04-01

    Our purpose was to find a method to create a large animal model of inducible photoreceptor damage. To this end, we tested in domestic swine the efficacy of two chemical toxins, known to create photoreceptor damage in other species: Iodoacetic Acid (IAA) and Sodium Iodate (NaIO(3)). Intravenous (IV) administration of NaIO(3) up to 90 mg/kg had no effect on retinal function and 110 mg/kg was lethal. IV administration of IAA (5-20 mg/kg) produced concentration-dependent changes in visual function as measured by full-field and multi-focal electroretinograms (ffERG and mfERG), and 30 mg/kg IAA was lethal. The IAA-induced effects measured at two weeks were stable through eight weeks post-injection, the last time point investigated. IAA at 7.5, 10, and 12 mg/kg produce a concentration-dependent reduction in both ffERG b-wave and mfERG N1-P1 amplitudes compared to baseline at all post-injection times. Comparisons of dark- and light-adapted ffERG b-wave amplitudes show a more significant loss of rod relative to cone function. The fundus of swine treated with ≥10 mg/kg IAA was abnormal with thinner retinal vessels and pale optic discs, and we found no evidence of bone spicule formation. Histological evaluations show concentration-dependent outer retinal damage that correlates with functional changes. We conclude that NaIO(3,) is not an effective toxin in swine. In contrast, IAA can be used to create a rapidly inducible, selective, stable and concentration-dependent model of photoreceptor damage in swine retina. Because of these attributes this large animal model of controlled photoreceptor damage should be useful in the investigation of treatments to replace damaged photoreceptors. PMID:22251455

  13. Analysis of multistate models for electromigration failure

    NASA Astrophysics Data System (ADS)

    Dwyer, V. M.

    2010-02-01

    The application of a multistate Markov chain is considered as a model of electromigration interconnect degradation and eventual failure. Such a model has already been used [Tan et al., J. Appl. Phys. 102, 103703 (2007)], maintaining that, in general, it leads to a failure distribution described by a gamma mixture, and that as a result, this type of distribution (rather than a lognormal) should be used as a prior in any Bayesian mode fitting and subsequent reliability budgeting. Although it appears that the model is able to produce reasonably realistic resistance curves R(t), we are unable to find any evidence that the failure distribution is a simple gamma mixture except under contrived conditions. The distributions generated are largely sums of exponentials (phase-type distributions), convolutions of gamma distributions with different scales, or roughly normal. We note also some inconsistencies in the derivation of the gamma mixture in the work cited above and conclude that, as it stands, the Markov chain model is probably unsuitable for electromigration modeling and a change from lognormal to gamma mixture distribution generally cannot be justified in this way. A hidden Markov model, which describes the interconnect behavior at time t rather than its resistance, in terms of generally observed physical processes such as void nucleating, slitlike growth (where the growth is slow and steady), transverse growth, current shunting (where the resistance jumps in value), etc., seems a more likely prospect, but treating failure in such a manner would still require significant justification.

  14. 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. PMID:23762159

  15. Accelerated Failure-Time Models of Graduation

    ERIC Educational Resources Information Center

    Chimka, Justin R.; Wang, Qilu

    2009-01-01

    This third article in a series describing survival analysis of engineering student retention and graduation introduces accelerated failure-time as an alternative to the Cox proportional hazards model to the context of student data. The new survival analysis of graduation data presented here assumes different distributions including exponential,…

  16. 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.

  17. 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

  18. 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. PMID:24867969

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

    PubMed

    Aguero, Jaume; 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

    2014-10-15

    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 Ca(2+)-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

  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. Modeling the Biomechanics of Swine Mastication – An Inverse Dynamics Approach

    PubMed Central

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

    2014-01-01

    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 <7N 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 0.37mm 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

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

    PubMed Central

    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. PMID:26339403

  3. Coenzyme Q10 protects ischemic myocardium in an open-chest swine model.

    PubMed

    Atar, D; Mortensen, S A; Flachs, H; Herzog, W R

    1993-01-01

    Myocardial stunning, defined as a reversible decrease in contractility after ischemia and reperfusion, may be a manifestation of reperfusion injury caused by free oxygen radical damage. The aim of this study was to test the hypothesis that pretreatment with coenzyme Q10 (ubiquinone), believed to act as a free radical scavenger, reduces myocardial stunning in a porcine model. Twelve swine were randomized to receive either oral supplementation with coenzyme Q10 or placebo for 20 days. A normothermic open-chest model was used with short occlusion (8 min) of the distal left descending coronary artery followed by reperfusion. Regional contractile function was measured with epicardial Doppler crystals in ischemic and nonischemic segments by measuring thickening fraction of the left ventricular wall during systole. Stunning time was defined as the elapsed time of reduced contractility until return to baseline. Coenzyme Q10 concentrations were measured in blood and homogenized myocardial tissue by high performance liquid chromatography. Plasma levels of reduced coenzyme Q10 (ubiquinol) were higher in swine pretreated with the experimental medication as compared to placebo (mean 0.45 mg/l versus 0.11 mg/l, respectively). Myocardial tissue concentrations, however, did not show any changes (mean 0.79 micrograms/mg dry weight versus 0.74 micrograms/mg). Stunning time was significantly reduced in coenzyme Q10 pretreated animals (13.7 +/- 7.7 min versus 32.8 +/- 3.1 min, P < 0.01). In conclusion, chronic pretreatment with coenzyme Q10 protects ischemic myocardium in an open-chest swine model. The beneficial effect of coenzyme Q10 on myocardial stunning may be due to protection from free radical mediated reperfusion injury. This protective effect seems to be generated by a humoral rather than intracellular mechanism. PMID:8241692

  4. 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. PMID:26339403

  5. 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.

  6. 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.

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

    PubMed

    Park, Jin Seok; Jeong, Seok; Kim, Joon Mee; Park, Sang Soon; Lee, Don Haeng

    2016-09-01

    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

  8. Comparison of isoflurane and α-chloralose in an anesthetized swine model of acute pulmonary embolism producing right ventricular dysfunction.

    PubMed

    Beam, Daren M; Neto-Neves, Evandro M; Stubblefield, William B; Alves, Nathan J; Tune, Johnathan D; Kline, Jeffrey A

    2015-02-01

    Pulmonary embolism (PE) is a leading cause of sudden cardiac death, and a model is needed for testing potential treatments. In developing a model, we compared the hemodynamic effects of isoflurane and α-chloralose in an acute swine model of PE because the choice of anesthesia will likely affect the cardiovascular responses of an animal to PE. At baseline, swine that received α-chloralose (n = 6) had a lower heart rate and cardiac output and higher SpO2, end-tidal CO2, and mean arterial pressure than did those given isoflurane (n = 9). After PE induction, swine given α-chloralose compared with isoflurane exhibited a lower heart rate (63 ± 10 compared with 116 ± 15 bpm) and peripheral arterial pressure (52 ± 12 compared with 61 ± 12 mm Hg); higher SpO2 (98% ± 3% compared with 95% ± 1%), end-tidal CO2 (35 ± 4 compared with 32 ± 5), and systolic blood pressure (121 ± 8 compared with 104 ± 20 mm Hg); and equivalent right ventricular:left ventricular ratios (1.32 ± 0.50 compared with 1.23 ± 0.19) and troponin I mean values (0.09 ± 0.07 ng/mL compared with 0.09 ± 0.06 ng/mL). Isoflurane was associated with widely variable fibrinogen and activated partial thromboplastin time. Intraexperiment mortality was 0 of 6 animals for α-chloralose and 2 of 9 swine for isoflurane. All swine anesthetized with α-chloralose survived with sustained pulmonary hypertension, RV-dilation-associated cardiac injury without the confounding vasodilatory or coagulatory effects of isoflurane. These data demonstrate the physiologic advantages of α-chloralose over isoflurane for anesthesia in a swine model of severe submassive PE. PMID:25730758

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

    PubMed Central

    Caballero, Montserrat; Morse, Justin C.; Halevi, Alexandra E.; Emodi, Omri; Pharaon, Michael R.; Wood, Jeyhan S.

    2015-01-01

    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. PMID:25837453

  10. Unique transcriptomic signature of omental adipose tissue in Ossabaw swine: a model of childhood obesity

    PubMed Central

    Toedebusch, Ryan G.; Roberts, Michael D.; Wells, Kevin D.; Company, Joseph M.; Kanosky, Kayla M.; Padilla, Jaume; Jenkins, Nathan T.; Perfield, James W.; Ibdah, Jamal A.; Booth, Frank W.

    2014-01-01

    To better understand the impact of childhood obesity on intra-abdominal adipose tissue phenotype, a complete transcriptomic analysis using deep RNA-sequencing (RNA-seq) was performed on omental adipose tissue (OMAT) obtained from lean and Western diet-induced obese juvenile Ossabaw swine. Obese animals had 88% greater body mass, 49% greater body fat content, and a 60% increase in OMAT adipocyte area (all P < 0.05) compared with lean pigs. RNA-seq revealed a 37% increase in the total transcript number in the OMAT of obese pigs. Ingenuity Pathway Analysis showed transcripts in obese OMAT were primarily enriched in the following categories: 1) development, 2) cellular function and maintenance, and 3) connective tissue development and function, while transcripts associated with RNA posttranslational modification, lipid metabolism, and small molecule biochemistry were reduced. DAVID and Gene Ontology analyses showed that many of the classically recognized gene pathways associated with adipose tissue dysfunction in obese adults including hypoxia, inflammation, angiogenesis were not altered in OMAT in our model. The current study indicates that obesity in juvenile Ossabaw swine is characterized by increases in overall OMAT transcript number and provides novel data describing early transcriptomic alterations that occur in response to excess caloric intake in visceral adipose tissue in a pig model of childhood obesity. PMID:24642759

  11. Brittle failure kinetics model for concrete

    SciTech Connect

    Silling, S.A.

    1997-03-01

    A new constitutive model is proposed for the modeling of penetration and large stress waves in concrete. Rate effects are incorporated explicitly into the damage evolution law, hence the term brittle failure kinetics. The damage variable parameterizes a family of Mohr-Coulomb strength curves. The model, which has been implemented in the CTH code, has been shown to reproduce some distinctive phenomena that occur in penetration of concrete targets. Among these are the sharp spike in deceleration of a rigid penetrator immediately after impact. Another is the size scale effect, which leads to a nonlinear scaling of penetration depth with penetrator size. This paper discusses the theory of the model and some results of an extensive validation effort.

  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. The adult Göttingen minipig as a model for chronic heart failure after myocardial infarction: focus on cardiovascular imaging and regenerative therapies.

    PubMed

    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

    2008-12-01

    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

  14. 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. PMID:26855331

  15. 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. PMID:23974904

  16. 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.

  17. 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.

  18. Analysis of air pollution from swine production by using air dispersion model and GIS in Quebec.

    PubMed

    Sarr, Joachim H; Goïta, Kalifa; Desmarais, Camille

    2010-01-01

    Swine production, the second most important contributor to Quebec's agricultural revenue, faces many problems. Intensive piggeries, with up to 599 animal units, are used to raise finishing pigs for slaughter. Among the great number of gaseous species emitted to the atmospheric environment from livestock buildings and manure storage units is NH3, which is one of the most important and most offensive with respect to human health. Under appropriate meteorological and topographical conditions, gaseous contaminants can spread and cause a public nuisance--up to a 1-km radius around the farm. To mitigate these effects, the Quebec Government adopted regulations that set minimum buffer distances to be observed by any expansion of an existing or new pig farm. The objectives of this study were (i) to assess the efficiency of the current buffer distance prescriptions in Quebec in mitigating effects of air pollution from swine units and (ii) to identify potential areas for establishing pig farm operations that will not be offensive to people. The air dispersion American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD) with receptors distributed at 1.6 km around each source was used first, followed by a spatial geographic information system (GIS) model. Results from the dispersion model showed that the highest hourly concentration with a 99.5% compliance frequency for a single farm was 3078.1 microg/m3 and exceeded the NH3 odor criterion hourly standard set by the Quebec Government at 183.4 microg/m3. Thus, for public safety, densely populated areas like housing developments must be located >1300 m from a pig farm. This distance is in the range of setback distances (723 to 1447 m) obtained by using abacuses defined in the L'Erable Regional County Municipality. That is why we can say the current rules established by the Quebec Government, if rigorously applied, can prevent odor nuisance, due to NH3 emission, from swine farms. In the spatial model

  19. Strength and failure models for epoxy mortar polymer concrete materials

    SciTech Connect

    Salami, M.R.; Zhao, S.

    1995-06-01

    Since the polymer concrete materials are used in construction, there is a need for developing a fundamental failure and constitutive model for predicting material behavior. The present research is undertaken as an initial step toward developing a fundamental failure and constitutive model for polymer concrete materials, as well as providing benchmark data on the strength and failure characteristics of material specimens for future work. The failure model will be developed based on introducing a failure function. This model will predict the changes in constitutive properties and resistance values in aggressive environments.

  20. 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...

  1. Implementation of a Chronic Unilateral Intraparenchymal Drug Delivery System in a Swine Model

    PubMed Central

    Kim, Inyong; Paek, Seungleal; Nelson, Brian D.; Knight, Emily J.; Marsh, Michael P.; Bieber, Allan J.; Bennet, Kevin E.; Lee, Kendall H.

    Background Systemic delivery of pharmacologic agents has led to many significant advances in the treatment of neurologic and psychiatric conditions. However, this approach has several limitations, including difficulty penetrating the blood-brain barrier and enzymatic degradation prior to reaching its intended target. Here, we describe the testing of a system allowing intraparenchymal (IPa) infusion of therapeutic agents directly to the appropriate anatomical targets, in a swine model. New Method Five male pigs underwent 3.0 T magnetic resonance (MR) guided placement of an IPa catheter into the dorso-medial putamen, using a combined system of the Leksell Stereotactic Arc, a Mayo-developed MRI-compatible pig head frame, and a custom-designed Fred Haer Company (FHC) delivery system. Results Our results show hemi-lateral coverage of the pig putamen is achievable from a single infusion point and that the volume of the bolus detected in each animal is uniform (1544±420mm3). Comparison with Existing Method The IPa infusion system is designed to isolate the intracranial catheter from bodily-induced forces while delivering drugs and molecules into the brain tissue by convection-enhanced delivery, with minimal-to-no catheter track backflow. Conclusion This study presents an innovative IPa drug delivery system, which includes a sophisticated catheter and implantable pump designed to deliver drugs and various molecules in a precise and controlled manner with limited backflow. It also demonstrates the efficacy of the delivery system, which has the potential to radically impact the treatment of a wide range of neurologic conditions. Lastly, the swine model used here has certain advantages for translation into clinical applications. PMID:24486877

  2. Ventricular Fibrillation Waveform Changes during Controlled Coronary Perfusion Using Extracorporeal Circulation in a Swine Model

    PubMed Central

    Kaufman, Christopher L.; Baetiong, Alvin; Radhakrishnan, Jeejabai

    2016-01-01

    Background Several characteristics of the ventricular fibrillation (VF) waveform have been found predictive of successful defibrillation and hypothesized to reflect the myocardial energy state. In an open-chest swine model of VF, we modeled “average CPR” using extracorporeal circulation (ECC) and assessed the time course of coronary blood flow, myocardial metabolism, and myocardial structure in relation to the amplitude spectral area (AMSA) of the VF waveform without artifacts related to chest compression. Methods VF was induced and left untreated for 8 minutes in 16 swine. ECC was then started adjusting its flow to maintain a coronary perfusion pressure of 10 mmHg for 10 minutes. AMSA was calculated in the frequency domain and analyzed continuously with a 2.1 s timeframe and a Tukey window that moved ahead every 0.5 s. Results AMSA progressively declined during untreated VF. With ECC, AMSA increased from 7.0 ± 1.9 mV·Hz (at minute 8) to 12.8 ± 3.3 mV·Hz (at minute 14) (p < 0.05) without subsequent increase and showing a modest correlation with coronary blood flow of borderline statistical significance (r = 0.489, p = 0.0547). Myocardial energy measurements showed marked reduction in phosphocreatine and moderate reduction in ATP with increases in ADP, AMP, and adenosine along with myocardial lactate, all indicative of ischemia. Yet, ischemia did not resolve during ECC despite a coronary blood flow of ~ 30% of baseline. Conclusion AMSA increased upon return of coronary blood flow during ECC. However, the maximal level was reached after ~ 6 minutes without further change. The significance of the findings for determining the optimal timing for delivering an electrical shock during resuscitation from VF remains to be further explored. PMID:27536996

  3. 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.

  4. A novel colonoscope with panoramic visualization detected more simulated polyps than conventional colonoscopy in a live swine model

    PubMed Central

    Gluck, Nathan; Fishman, Sigal; Melhem, Alaa; Goldfarb, Sharon; Halpern, Zamir; Santo, Erwin

    2015-01-01

    Background and study aims: The Aer-O-Scope™ Colonoscope System (AOS) combines panoramic 360° view with standard forward view. We assessed the AOS’s ability to identify lesions implanted in live swine, compared to conventional colonoscopy (CC). Patients and methods: Twelve swine colons were surgically ligated and beads sewn within. Five procedures (3 AOS and 2 CC) were performed on each swine and findings reported. Physicians were blinded to number, size, and color of beads. The sequence of procedures and physicians was randomized. Pigs, physicians, and colonoscopes were randomly alternated between examination rooms, maintaining physician blindness. Two independent blinded physicians interpreted procedure videos offline. Results: A total of 259 /273 (94.9 %) of lesions were visualized by AOS compared to 158 /182 with CC (86.8 %) (P = 0.002). Miss rates of lesions ≥ 6 mm were 2.6 % and 10.5 %, respectively (P = 0.022), and 6.9 % and 15.1 %, respectively, for lesions < 6 mm (P = 0.031). Mean agreement between AOS and CC for lesion detection was 88.3 %. The benefit of AOS was maintained in offline video review. Conclusions: AOS, featuring panoramic 360° view, demonstrated high detection rates for simulated colonic lesions in a live swine model. PMID:26716128

  5. Resveratrol Improves Myocardial Perfusion in a Swine Model of Hypercholesterolemia and Chronic Myocardial Ischemia

    PubMed Central

    Robich, Michael P.; Osipov, Robert M.; Nezafat, Reza; Feng, Jun; Clements, Richard T.; Bianchi, Cesario; Boodhwani, Munir; Coady, Michael A.; Laham, Roger J.; Sellke, Frank W.

    2010-01-01

    Introduction Resveratrol may provide protection against coronary artery disease. We hypothesized that supplemental resveratrol will improve cardiac perfusion in the ischemic territory of swine with hypercholesterolemia and chronic myocardial ischemia. Methods and Results Yorkshire swine were fed either a normal diet (control, n=7), a hypercholesterolemic diet (HCC, n=7), or a hypercholesterolemic diet with supplemental resveratrol (100 mg/kg/day orally, HCRV, n=7). Four weeks later, an ameroid constrictor was placed on the left circumflex artery. Animals underwent cardiac magnetic resonance imaging and coronary angiography 7 weeks later, prior to sacrifice and tissue harvest. Total cholesterol was lowered about 30% in HCRV animals (p<0.001). Regional wall motion analysis demonstrated a significant decrease in inferolateral function from baseline to 7 weeks in HCC swine (p=0.04). There was no significant change in regional function in HCRV swine from baseline to 7 weeks (p=0.32). Tissue blood flow during stress was 2.8 fold greater in HCRV swine when compared to HCC swine (p=0.04). Endothelial dependent microvascular relaxation response to Substance P was diminished in HCC swine which was rescued by resveratrol treatment (p=0.004). Capillary density (PECAM-1 staining) demonstrated fewer capillaries in both HCC and HCRV swine v. control swine (p=0.02). Immunoblot analysis demonstrated significantly greater expression in HCRV v. HCC swine of the following markers of angiogenesis: VEGF (p=0.002), peNOS(ser1177)(p=0.04), NFkB (p=0.004), and pAkt(thr308)(p=0.001). Conclusion Supplemental resveratrol attenuates regional wall motion abnormalities, improves myocardial perfusion in the collateral dependent region, preserves endothelial dependent coronary vessel function, and upregulates markers of angiogenesis associated with the VEGF signaling pathway. PMID:20837905

  6. 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...

  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. Genome Sequences of Four Strains of Mycobacterium avium subsp. hominissuis, Isolated from Swine and Humans, Differing in Virulence in a Murine Intranasal Infection Model.

    PubMed

    Bruffaerts, N; Vluggen, C; Duytschaever, L; Mathys, V; Saegerman, C; Chapeira, O; Huygen, K

    2016-01-01

    This paper announces the genome sequences of four strains of Mycobacterium avium subsp. hominissuis, isolated from cases of lymphadenopathy in swine and humans, differing in virulence in a murine intranasal infection model. PMID:27313293

  9. Genome Sequences of Four Strains of Mycobacterium avium subsp. hominissuis, Isolated from Swine and Humans, Differing in Virulence in a Murine Intranasal Infection Model

    PubMed Central

    Bruffaerts, N.; Vluggen, C.; Duytschaever, L.; Mathys, V.; Saegerman, C.; Chapeira, O.

    2016-01-01

    This paper announces the genome sequences of four strains of Mycobacterium avium subsp. hominissuis, isolated from cases of lymphadenopathy in swine and humans, differing in virulence in a murine intranasal infection model. PMID:27313293

  10. Eprosartan improves cardiac function in swine working heart model of ischemia-reperfusion injury

    PubMed Central

    Weymann, Alexander; Sabashnikov, Anton; Patil, Nikhil P.; Konertz, Wolfgang; Modersohn, Diethelm; Dohmen, Pascal M.

    2014-01-01

    Background Eprosartan is an angiotensin II receptor antagonist used as an antihypertensive. We sought to evaluate the regional effect of Eprosartan on postinfarct ventricular remodeling and myocardial function in an isolated swine working heart model of ischemia-reperfusion injury. Material/Methods 22 swine hearts were perfused with the Langendorff perfusion apparatus under standard experimental conditions. Myocardial ischemia was induced by a 10-min left anterior descending artery ligation. Hearts were reperfused with either saline (control group, n=11), or Eprosartan (treatment group, n=11). Left ventricular pressure (LVP) and regional heart parameters such as intramyocardial pressure (IMP), wall thickening rate (WTh), and pressure-length-loops (PLL) were measured at baseline and after 30 min of reperfusion. Results Measured parameters were statistically similar between the 2 groups at baseline. The administration of Eprosartan led to a significantly better recovery of IMP and WTh: 44.4±2.5 mmHg vs. 51.2±3.3 mmHg, p<0.001 and 3.8±0.4 μm vs. 4.4±0.3 μm, p=0.001, respectively. PLL were also significantly higher in the treatment group following reperfusion (21694±3259 units vs. 31267±3429 units, p<0.01). There was no difference in the LVP response to Eprosartan versus controls (63.6±3.0 mmHg vs. 62.5±3.1 mmHg, p=0.400). Conclusions Pre-treatment with Eprosartan is associated with a significant improvement in regional cardiac function under ischemic conditions. Pharmacological treatment with eprosartan may exert a direct cardioprotective effect on ischemic myocardium. PMID:24762635

  11. 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

  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. PMID:24433305

  13. 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

  14. Modeling Pathologies of Diastolic and Systolic Heart Failure.

    PubMed

    Genet, M; Lee, L C; Baillargeon, B; Guccione, J M; Kuhl, E

    2016-01-01

    Chronic heart failure is a medical condition that involves structural and functional changes of the heart and a progressive reduction in cardiac output. Heart failure is classified into two categories: diastolic heart failure, a thickening of the ventricular wall associated with impaired filling; and systolic heart failure, a dilation of the ventricles associated with reduced pump function. In theory, the pathophysiology of heart failure is well understood. In practice, however, heart failure is highly sensitive to cardiac microstructure, geometry, and loading. This makes it virtually impossible to predict the time line of heart failure for a diseased individual. Here we show that computational modeling allows us to integrate knowledge from different scales to create an individualized model for cardiac growth and remodeling during chronic heart failure. Our model naturally connects molecular events of parallel and serial sarcomere deposition with cellular phenomena of myofibrillogenesis and sarcomerogenesis to whole organ function. Our simulations predict chronic alterations in wall thickness, chamber size, and cardiac geometry, which agree favorably with the clinical observations in patients with diastolic and systolic heart failure. In contrast to existing single- or bi-ventricular models, our new four-chamber model can also predict characteristic secondary effects including papillary muscle dislocation, annular dilation, regurgitant flow, and outflow obstruction. Our prototype study suggests that computational modeling provides a patient-specific window into the progression of heart failure with a view towards personalized treatment planning. PMID:26043672

  15. Measurement and modeling of hydrogen sulfide lagoon emissions from a swine concentrated animal feeding operation.

    PubMed

    Rumsey, Ian C; Aneja, Viney P

    2014-01-01

    Hydrogen sulfide (H2S) emissions were determined from an anaerobic lagoon at a swine concentrated animal feeding operation (CAFO) in North Carolina. Measurements of H2S were made continuously from an anaerobic lagoon using a dynamic flow-through chamber for ∼ 1 week during each of the four seasonal periods from June 2007 through April 2008. H2S lagoon fluxes were highest in the summer with a flux of 3.81 ± 3.24 μg m(-2) min(-1) and lowest in the winter with a flux of 0.08 ± 0.09 μg m(-2) min(-1). An air-manure interface (A-MI) mass transfer model was developed to predict H2S manure emissions. The accuracy of the A-MI mass transfer model in predicting H2S manure emissions was comprehensively evaluated by comparing the model predicted emissions to the continuously measured lagoon emissions using data from all four seasonal periods. In comparison to this measurement data, the A-MI mass transfer model performed well in predicting H2S fluxes with a slope of 1.13 and an r(2) value of 0.60, and a mean bias value of 0.655 μg m(-2) min(-1). The A-MI mass transfer model also performed fairly well in predicting diurnal H2S lagoon flux trends. PMID:24387076

  16. 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.

  17. 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

  18. 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 ...

  19. 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.

  20. Cone Photoreceptors Develop Normally in the Absence of Functional Rod Photoreceptors in a Transgenic Swine Model of Retinitis Pigmentosa

    PubMed Central

    Fernandez de Castro, Juan P.; Scott, Patrick A.; Fransen, James W.; Demas, James; DeMarco, Paul J.; Kaplan, Henry J.; McCall, Maureen A.

    2014-01-01

    Purpose. Human and swine retinas have morphological and functional similarities. In the absence of primate models, the swine is an attractive model to study retinal function and disease, with its cone-rich visual streak, our ability to manipulate their genome, and the differences in susceptibility of rod and cone photoreceptors to disease. We characterized the normal development of cone function and its subsequent decline in a P23H rhodopsin transgenic (TgP23H) miniswine model of autosomal dominant RP. Methods. Semen from TgP23H miniswine 53-1 inseminated domestic swine and produced TgP23H and Wt hybrid littermates. Retinal function was evaluated using ERGs between postnatal days (P) 14 and 120. Retinal ganglion cell (RGC) responses were recorded to full-field stimuli at several intensities. Retinal morphology was assessed using light and electron microscopy. Results. Scotopic retinal function matures in Wt pigs up to P60, but never develops in TgP23H pigs. Wt and TgP23H photopic vision matures similarly up to P30 and diverges at P60 where TgP23H cone vision declines. There are fewer TgP23H RGCs with visually evoked responses at all ages and their response to light is compromised. Photoreceptor morphological changes mirror these functional changes. Conclusions. Lack of early scotopic function in TgP23H swine suggests it as a model of an aggressive form of RP. In this mammalian model of RP, normal cone function develops independent of rod function. Therefore, its retina represents a system in which therapies to rescue cones can be developed to prolong photopic visual function in RP patients. PMID:24618325

  1. 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. PMID:24565255

  2. 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.

  3. Blinded Evaluation of Combination Drug Therapy for Prolonged Ventricular Fibrillation Using a Swine Model of Sudden Cardiac Arrest.

    PubMed

    Mader, Timothy J; Coute, Ryan A; Kellogg, Adam R; Nathanson, Brian H

    2016-01-01

    Despite experimental evidence supporting the use of resuscitation drugs in the treatment of sudden cardiac arrest (CA), there are no good human clinical data to support the decades-old practice of giving these medications during out-of-hospital CA resuscitation. We hypothesized that the lack of efficacy in clinical practice in ventricular fibrillation (VF) is the failure-based manner in which resuscitation drugs have historically been administered (one at a time interspersed with chest compressions and a defibrillation attempt, giving the next only if the previous one was ineffective). The aim of this study was to determine if giving and circulating a combination of commonly available, historically used resuscitation drugs together, prior to the first defibrillation attempt after prolonged VF, might improve short-term outcomes compared with the failure-based serial drug approach used in the past. We used a well-established swine model of sudden prolonged untreated VF. Animals were randomized to receive epinephrine (0.01 mg/kg), vasopressin (0.5 U/kg), amiodarone (4 mg/kg), and sodium bicarbonate (1.0 mEq/kg) in series (SERIES group [n = 53]) or a combination of epinephrine (0.01 mg/kg), vasopressin (0.5 U/kg), amiodarone (4 mg/kg), sodium bicarbonate (1.0 mEq/kg), and metoprolol (0.2 mg/kg) (COCKTAIL group) delivered in rapid succession at the beginning of the attempted resuscitation (n = 27). Data were analyzed descriptively. Baseline characteristics and chemistries between the two groups were the same. Termination of VF was statistically similar in the two groups: 88.7% (47/53) versus 85.2% (23/27) p = 0.66, with an adjusted relative risk ratio (RRR) of 0.94 (0.37, 1.15). However, ROSC was higher in the SERIES group (56.6% [30/53] versus 22.2% [6/27], adjusted RRR = 2.83; [1.16, 3.84] p = 0.029) as was 20-minute survival (52.8% [28/53] versus 18.5% [5/27], adjusted RRR = 3.15 [1.14, 4.54] p = 0.032). The combination of drugs studied, at these dosages

  4. 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.

  5. A model for methane production in anaerobic digestion of swine wastewater.

    PubMed

    Yang, Hongnan; Deng, Liangwei; Liu, Gangjin; Yang, Di; Liu, Yi; Chen, Ziai

    2016-10-01

    A study was conducted using a laboratory-scale anaerobic sequencing batch digester to investigate the quantitative influence of organic loading rates (OLRs) on the methane production rate during digestion of swine wastewater at temperatures between 15 °C and 35 °C. The volumetric production rate of methane (Rp) at different OLRs and temperatures was obtained. The maximum volumetric methane production rates (Rpmax) were 0.136, 0.796, 1.294, 1.527 and 1.952 LCH4 L(-1) d(-1) at corresponding organic loading rates of 1.2, 3.6, 5.6, 5.6 and 7.2 g volatile solids L(-1) d(-1), respectively, which occurred at 15, 20, 25, 30 and 35 °C, respectively. A new model was developed to describe the quantitative relationship between Rp and OLR. In addition to the maximum volumetric methane production rate (Rpmax) and the half-saturation constant (KLR) commonly used in previous models such as the modified Stover-Kincannon model and Deng model, the new model introduced a new index (KD) that denoted the speed of volumetric methane production rate approaching the maximum as a function of temperature. The new model more satisfactorily described the influence of OLR on the rate of methane production than other models as confirmed by higher determination coefficients (R(2)) (0.9717-0.9900) and lower bias between the experimental and predicted data in terms of the root mean square error and the Akaike Information Criterion. Data from other published research also validated the applicability and generality of the new kinetic model to different types of wastewater. PMID:27395030

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

    PubMed

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

    2009-01-01

    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. PMID:19545404

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

    PubMed Central

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

    2009-01-01

    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 R0~2: 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. PMID:19545404

  8. Modelling the effectiveness and risks of vaccination strategies to control classical swine fever epidemics

    PubMed Central

    Backer, Jantien A.; Hagenaars, Thomas J.; van Roermund, Herman J.W.; de Jong, Mart C.M.

    2009-01-01

    In a recent update of the Dutch contingency plan for controlling outbreaks of classical swine fever (CSF), emergency vaccination is preferred to large-scale pre-emptive culling. This policy change raised two questions: can emergency vaccination be as effective as pre-emptive culling, and what are the implications for showing freedom of infection? Here, we integrate quantitative information available on CSF virus transmission and vaccination effects into a stochastic mathematical model that describes the transmission dynamics at the level of animals, farms and livestock areas. This multilevel approach connects individual-level interventions to large-scale effects. Using this model, we compare the performance of five different control strategies applied to hypothetical CSF epidemics in The Netherlands and, for each of these strategies, we study the properties of three different screening scenarios to show freedom of infection. We find that vaccination in a ring of 2 km radius around a detected infection source is as effective as ring culling in a 1 km radius. Feasible screening scenarios, adapted to the use of emergency vaccination, can reduce the enhanced risks of (initially) undetected farm outbreaks by targeting vaccinated farms. Altogether, our results suggest that emergency vaccination against CSF can be equally effective and safe as pre-emptive culling. PMID:19054739

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

    PubMed Central

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

    2015-01-01

    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. PMID:26473349

  10. 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

  11. 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

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

    PubMed

    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

    2014-09-01

    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

  13. 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

  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. PMID:27391689

  15. 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

  16. Analysis of Swine Leukocyte Antigen Haplotypes in Yucatan Miniature Pigs Used as Biomedical Model Animal.

    PubMed

    Choi, Nu-Ri; Seo, Dong-Won; Choi, Ki-Myung; Ko, Na-Young; Kim, Ji-Ho; Kim, Hyun-Il; Jung, Woo-Young; Lee, Jun-Heon

    2016-03-01

    The porcine major histocompatibility complex (MHC) is called swine leukocyte antigen (SLA), which controls immune responses and transplantation reactions. The SLA is mapped on pig chromosome 7 (SSC7) near the centromere. In this study, 3 class I (SLA-1, SLA-3, and SLA-2) and 3 class II (DRB1, DQB1, and DQA) genes were used for investigation of SLA haplotypes in Yucatan miniature pigs in Korea. This pig breed is a well-known model organism for biomedical research worldwide. The current study indicated that Korean Yucatan pig population had 3 Class I haplotypes (Lr-4.0, Lr-6.0, and Lr-25.0) and 3 class II haplotypes (Lr-0.5, Lr-0.7, and Lr-0.25). The combinations of SLA class I and II haplotype together, 2 homozygous (Lr-4.5/4.5 and Lr-6.7/6.7) and 3 heterozygous (Lr-4.5/6.7, Lr-4.5/25.25, and Lr-6.7/25.25) haplotypes were identified, including previously unidentified new heterozygous haplotypes (Lr-4.5/4.7). In addition, a new SLA allele typing method using Agilent 2100 bioanalyzer was developed that permitted more rapid identification of SLA haplotypes. These results will facilitate the breeding of SLA homozygous Yucatan pigs and will expedite the possible use of these pigs for the biomedical research, especially xenotransplantation research. PMID:26950861

  17. Analysis of Swine Leukocyte Antigen Haplotypes in Yucatan Miniature Pigs Used as Biomedical Model Animal

    PubMed Central

    Choi, Nu-Ri; Seo, Dong-Won; Choi, Ki-Myung; Ko, Na-Young; Kim, Ji-Ho; Kim, Hyun-Il; Jung, Woo-Young; Lee, Jun-Heon

    2016-01-01

    The porcine major histocompatibility complex (MHC) is called swine leukocyte antigen (SLA), which controls immune responses and transplantation reactions. The SLA is mapped on pig chromosome 7 (SSC7) near the centromere. In this study, 3 class I (SLA-1, SLA-3, and SLA-2) and 3 class II (DRB1, DQB1, and DQA) genes were used for investigation of SLA haplotypes in Yucatan miniature pigs in Korea. This pig breed is a well-known model organism for biomedical research worldwide. The current study indicated that Korean Yucatan pig population had 3 Class I haplotypes (Lr-4.0, Lr-6.0, and Lr-25.0) and 3 class II haplotypes (Lr-0.5, Lr-0.7, and Lr-0.25). The combinations of SLA class I and II haplotype together, 2 homozygous (Lr-4.5/4.5 and Lr-6.7/6.7) and 3 heterozygous (Lr-4.5/6.7, Lr-4.5/25.25, and Lr-6.7/25.25) haplotypes were identified, including previously unidentified new heterozygous haplotypes (Lr-4.5/4.7). In addition, a new SLA allele typing method using Agilent 2100 bioanalyzer was developed that permitted more rapid identification of SLA haplotypes. These results will facilitate the breeding of SLA homozygous Yucatan pigs and will expedite the possible use of these pigs for the biomedical research, especially xenotransplantation research. PMID:26950861

  18. 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.

  19. Test of a novel miniature blood pressure sensor in the coronary arteries of a swine model

    NASA Astrophysics Data System (ADS)

    Wu, Nan; Sun, Kai; Zou, Xiaotian; Barringhaus, Kurt; Wang, Xingwei

    2011-06-01

    Fractional flow reserve (FFR) has proven to be very useful in diagnosis of narrowed coronary arteries. It is a technique that is used in coronary catheterization to measure blood pressure difference across a coronary artery stenosis in maximal flow. In-vivo blood pressure measurement is critical in FFR diagnosis. This paper presents a novel miniature all-optical fiber blood pressure sensor. It is based on Fabry-Perot (FP) interferometry principle. The FP cavity was fabricated by directly wet etching the fiber tip. Then, a diaphragm with well-controlled thickness was bonded to the end face of the fiber using the thermal bonding technique. Finally, the sensor was packaged with a bio-compatible and flexible coil for animal tests. A 25-50 kg Yorkshire swine model was introduced as the animal test target. The left anterior descending coronary artery (LAD) was exposed, and beyond the takeoff of the largest diagonal branch, a 3.0 mm vascular occluder was secured. Firstly, standard invasive manometry was used to obtain the blood pressure as baseline. Next, a guiding catheter was introduced into the ostium of the left main coronary artery, and the miniature blood pressure sensor was advanced into the LAD at a point beyond the vascular occlude. The blood pressure beyond the vascular occlude was recorded. The sensor successfully recorded the blood pressure at both near-end and far-end of the vascular occluder.

  20. Effect of model uncertainty on failure detection - The threshold selector

    NASA Technical Reports Server (NTRS)

    Emami-Naeini, Abbas; Akhter, Muhammad M.; Rock, Stephen M.

    1988-01-01

    The performance of all failure detection, isolation, and accomodation (DIA) algorithms is influenced by the presence of model uncertainty. A unique framework is presented to incorporate a knowledge of modeling error in the analysis and design of failure detection systems. The tools being used are very similar to those in robust control theory. A concept is introduced called the threshold selector, which is a nonlinear inequality whose solution defines the set of detectable sensor failure signals. The threshold selector represents an innovative tool for analysis and synthesis of DIA algorithms. It identifies the optimal threshold to be used in innovations-based DIA algorithms. The optimal threshold is shown to be a function of the bound on modeling errors, the noise properties, the speed of DIA filters, and the classes of reference and failure signals. The size of the smallest detectable failure is also determined. The results are applied to a multivariable turbofan jet engine example, which demonstrates improvements compared to previous studies.

  1. 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. PMID:25219283

  2. Experimental models of hepatotoxicity related to acute liver failure.

    PubMed

    Maes, Michaël; Vinken, Mathieu; Jaeschke, Hartmut

    2016-01-01

    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

  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. A Model Expert System For Machine Failure Diagnosis (MED)

    NASA Astrophysics Data System (ADS)

    Liqun, Yin

    1987-05-01

    MED is a model expert system for machine failure diagnosis. MED can help the repairer quickly determine milling machine electrical failure. The key points in MED are a simple method to deal with the "subsequent visit" problem in machine failure diagnosis, a weighted list to interfere in the control of AGENDA to imitate an expert's continuous thinking process and to keep away erratic questioning and problem running away caused by probabilistic reasoning, the structuralized AGENDA, the characteristics of machine failure diagnosis and people's thinking pattern in faulure diagnosis. The structuralized AGENDA gives an idea to supply a more powerful as well as flexible control strategy in best-first search by using AGENDA. The "subsequent visit" problem is a very complicated task to solve, it will be convenient to deal with it by using a simple method to keep from consuming too much time in urgent situations. Weighted list also gives a method to improve control in inference of expert system. The characteristics of machine failure diagnosis and people's thinking pattern are both important for building a machine failure diagnosis expert system. When being told failure phenomena, MED can determine failure causes through dialogue. MED is written in LISP and run in UNIVAC 1100/10 and IBM PC/XT computers. The average diagnosis time per failure is 11 seconds to CPU, 2 minites to terminal operation, and 11 minites to a skilful repairer.

  5. Testing the Efficacy of Pharmacological Agents in a Pericardial Target Delivery Model in the Swine.

    PubMed

    Iles, Tinen L; Howard, Brian; Howard, Stephen; Quallich, Stephen; Rolfes, Christopher; Richardson, Eric; Iaizzo, Hanna R; Iaizzo, Paul A

    2016-01-01

    To date, many pharmacological agents used to treat or prevent arrhythmias in open-heart cases create undesired systemic side effects. For example, antiarrhythmic drugs administered intravenously can produce drops in systemic pressure in the already compromised cardiac patient. While performing open-heart procedures, surgeons will often either create a small port or form a pericardial cradle to create suitable fields for operation. This access yields opportunities for target pharmacological delivery (antiarrhythmic or ischemic preconditioning agents) directly to the myocardial tissue without undesired side effects. We have developed a swine model for testing pharmacological agents for target delivery within the pericardial fluid. While fully anesthetized, each animal was instrumented with a Swan-Ganz catheter as well as left and right ventricle pressure catheters, and pacing leads were placed in the right atrial appendage and the right ventricle. A medial sternotomy was then performed and a pericardial access cradle was created; a plunge pacing lead was placed in the left atrial appendage and a bipolar pacing lead was placed in the left ventricle. Utilizing a programmer and a cardiac mapping system, the refractory period of the atrioventricular node (AVN), atria and ventricles was determined. In addition, atrial fibrillation (AF) induction was produced utilizing a Grass stimulator and time in AF was observed. These measurements were performed prior to treatment, as well as 30 min and 60 min after pericardial treatment. Additional time points were added for selected studies. The heart was then cardiopleged and reanimated in a four chamber working mode. Pressure measurements and function were recorded for 1 hr after reanimation. This treatment strategy model allowed us to observe the effects of pharmacological agents that may decrease the incidence of cardiac arrhythmias and/or ischemic damage, during and after open-heart surgery. PMID:27500319

  6. 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

  7. 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...

  8. Hemodynamic and metabolic efficacy of dopamine versus norepinephrine in a brain-dead swine model.

    PubMed

    Zaky, Ahmed; Pretto, Ernesto A; Earle, Steven A; Piraccini, Emanuele; Zuccarelli, Jennifer E; Arheart, Kristopher L; Proctor, Kenneth G

    2008-09-01

    We tested the hypothesis that hepatosplanchnic and systemic hemodynamics are improved with equi-effective doses of dopamine (DA) versus norepinephrine (NE) in a brain-dead swine model. Pigs (n = 18) were anesthetized and ventilated. Brain death was induced by epidural balloon inflation, hypoventilation, and hypoxia. After 30 minutes, mechanical ventilation was restored without anesthesia. During 60 and until 480 minutes, half received DA (10 microg/kg/minute) and half received NE (0.1 microg/kg/minute) titrated to a mean arterial pressure (MAP) > 60 mm Hg with supplemental fluid to maintain a central venous pressure > 8 mm Hg. Hemodynamics, hepatic laser Doppler blood flow, and hepatic and gastric tissue oxygenation with near-infrared spectroscopy were continuously monitored. Serial blood samples were analyzed for blood gases and electrolytes, coagulation changes, and serum chemistries. Balloon inflation caused brain death and autonomic storm, and 8 of 18 were nonsurvivors. After 30 minutes, the MAP, mixed venous O(2) saturation, and partial pressure of arterial oxygen values decreased to 37 +/- 2 mm Hg, 38 +/- 4, and 49 +/- 8 mm Hg, respectively. Serum lactate increased to 5.4 +/- 0.7 mM. Among survivors (n = 10), MAP stabilized with either pressor. Urine output was maintained (>1 mL/kg/hour), but creatinine increased >30% with respect to the baseline. Tachyphylaxis developed with NE but not with DA (P < 0.05). Cardiac index was higher with DA versus NE (P < 0.05). There were no differences in stroke volume, metabolic indices, or liver blood flow. Liver tissue O(2) was higher with DA versus NE at 8 hours (P < 0.05). Coagulation tests and liver enzymes were similar with NE versus DA (P > 0.05). In conclusion, after brain death, cardiac index and hepatic oxygenation were significantly improved with equi-effective doses of DA versus NE. PMID:18756452

  9. 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. PMID:25224310

  10. 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. PMID:23664639

  11. 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

  12. 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...

  13. Anesthesia in swine : optimizing a laboratory model to optimize translational research.

    PubMed

    Pehböck, D; Dietrich, H; Klima, G; Paal, P; Lindner, K H; Wenzel, V

    2015-01-01

    In order to extrapolate novel therapies from the bench to the bedside (translational research), animal experiments are scientifically necessary. Swine are popular laboratory animals as their cardiorespiratory physiology is very similar to humans. Every study has to be approved by the local and/or national animal ethical committees. As swine are extremely sensitive to stress the primary goal is therefore to provide a calm, stress-free environment in both housing and experimental facilities. Swine should be properly sedated for transport and normothermia needs to be ensured. It is recommended to commence anesthesia by injecting ketamine and propofol followed by endotracheal intubation during spontaneous breathing. After intubation, anesthesia maintenance is performed with morphine or piritramide, propofol and rocuronium and routine monitoring is applied analogue to a clinical operating theater for humans. Normothermia (38.5 °C) needs to be ensured. While surgical procedures can be readily extrapolated from a human operating theater to swine, non-anesthesiologist scientists may lose the animal rapidly due to airway management problems. Vascular access can be secured by cut-downs or ultrasound-guided techniques in the inguinal and the neck region. For humane euthanasia of pigs, morphine, followed by propofol, rocuronium and potassium chloride are recommended. As radical animal right groups may threaten scientists, it is prudent that animal laboratories have unmarked entrance doors, are located in buildings that are not accessible to the public and strictly controlled access of laboratory staff is enforced. In conclusion, swine are an excellent laboratory animal for bench to bedside research and can be managed properly when basic knowledge and adequate skills on careful handling, anesthesia and surgical considerations are present. PMID:25384955

  14. 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.

  15. A Pro23His Mutation Alters Prenatal Rod Photoreceptor Morphology in a Transgenic Swine Model of Retinitis Pigmentosa

    PubMed Central

    Scott, Patrick A.; Fernandez de Castro, Juan P.; Kaplan, Henry J.; McCall, Maureen A.

    2014-01-01

    Purpose. Functional studies have detected deficits in retinal signaling in asymptomatic children from families with inherited autosomal dominant retinitis pigmentosa (RP). Whether retinal abnormalities are present earlier during gestation or shortly after birth in a subset of children with autosomal dominant RP is unknown and no appropriate animal RP model possessing visual function at birth has been available to examine this possibility. In a recently developed transgenic P23H (TgP23H) rhodopsin swine model of RP, we tracked changes in pre- and early postnatal retinal morphology, as well as early postnatal retinal function. Methods. Domestic swine inseminated with semen from a TgP23H miniswine founder produced TgP23H hybrid and wild type (Wt) littermates. Outer retinal morphology was assessed at light and electron microscopic levels between embryonic (E) and postnatal (P) day E85 to P3. Retinal function was evaluated using the full field electroretinogram at P3. Results. Embryonic TgP23H rod photoreceptors are malformed and their rhodopsin expression pattern is abnormal. Consistent with morphological abnormalities, rod-driven function is absent at P3. In contrast, TgP23H and Wt cone photoreceptor morphology (E85–P3) and cone-driven retinal function (P3) are similar. Conclusions. Prenatal expression of mutant rhodopsin alters the normal morphological and functional development of rod photoreceptors in TgP23H swine embryos. Despite this significant change, cone photoreceptors are unaffected. Human infants with similarly aggressive RP might never have rod vision, although cone vision would be unaffected. Such aggressive forms of RP in preverbal children would require early intervention to delay or prevent functional blindness. PMID:24618321

  16. Modeling Finite-Time Failure Probabilities in Risk Analysis Applications.

    PubMed

    Dimitrova, Dimitrina S; Kaishev, Vladimir K; Zhao, Shouqi

    2015-10-01

    In this article, we introduce a framework for analyzing the risk of systems failure based on estimating the failure probability. The latter is defined as the probability that a certain risk process, characterizing the operations of a system, reaches a possibly time-dependent critical risk level within a finite-time interval. Under general assumptions, we define two dually connected models for the risk process and derive explicit expressions for the failure probability and also the joint probability of the time of the occurrence of failure and the excess of the risk process over the risk level. We illustrate how these probabilistic models and results can be successfully applied in several important areas of risk analysis, among which are systems reliability, inventory management, flood control via dam management, infectious disease spread, and financial insolvency. Numerical illustrations are also presented. PMID:26010201

  17. 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.

  18. 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.

  19. Repetitive TASER X26 discharge resulted in adverse physiologic events with a dose-response relationship related to the duration of discharge in anesthetized swine model.

    PubMed

    Park, Eun-Jung; Choi, Sang-Cheon; Ahn, Jung-Hwan; Min, Young-Gi

    2013-01-01

    The objectives of our study were to investigate the dose-response relationship of the TASER X26 discharge duration in an anesthetized swine model. Fourteen swines were anesthetized and then exposed to TASER X26 discharge for 5 sec (n = 5) or for 10 sec (n = 6). The sham control group (n = 3) was anesthetized and studied using the same protocol except TASER X26 discharges during the experiments. Hemodynamic parameters were obtained. Blood pressure and total peripheral resistance decreased significantly after TASER discharge and returned to baseline value at 15 min after 5 sec of TASER discharge but did not return to baseline values during the 30-min observation period after 10 sec of TASER discharge. Repetitive TASER X26 discharge resulted in adverse physiologic events with a dose-response relationship related to the duration of TASER X26 discharge in an anesthetized swine model. PMID:23066880

  20. Failure analysis and modeling of a VAXcluster system

    NASA Technical Reports Server (NTRS)

    Tang, Dong; Iyer, Ravishankar K.; Subramani, Sujatha S.

    1990-01-01

    This paper discusses the results of a measurement-based analysis of real error data collected from a DEC VAXcluster multicomputer system. In addition to evaluating basic system dependability characteristics such as error and failure distributions and hazard rates for both individual machines and for the VAXcluster, reward models were developed to analyze the impact of failures on the system as a whole. The results show that more than 46 percent of all failures were due to errors in shared resources. This is despite the fact that these errors have a recovery probability greater than 0.99. The hazard rate calculations show that not only errors, but also failures occur in bursts. Approximately 40 percent of all failures occur in bursts and involved multiple machines. This result indicates that correlated failures are significant. Analysis of rewards shows that software errors have the lowest reward (0.05 vs 0.74 for disk errors). The expected reward rate (reliability measure) of the VAXcluster drops to 0.5 in 18 hours for the 7-out-of-7 model and in 80 days for the 3-out-of-7 model.

  1. Bone Marrow Mesenchymal Stem Cells (BM-MSCs) Improve Heart Function in Swine Myocardial Infarction Model through Paracrine Effects

    PubMed Central

    Cai, Min; Shen, Rui; Song, Lei; Lu, Minjie; Wang, Jianguang; Zhao, Shihua; Tang, Yue; Meng, Xianmin; Li, Zongjin; He, Zuo-Xiang

    2016-01-01

    Stem cells are promising for the treatment of myocardial infarction (MI) and large animal models should be used to better understand the full spectrum of stem cell actions and preclinical evidences. In this study, bone marrow mesenchymal stem cells (BM-MSCs) were transplanted into swine heart ischemia model. To detect glucose metabolism in global left ventricular myocardium and regional myocardium, combined with assessment of cardiac function, positron emission tomography-computer tomography (PET-CT) and magnetic resonance imaging (MRI) were performed. To study the changes of glucose transporters and glucose metabolism-related enzymes and the signal transduction pathway, RT-PCR, Western-blot, and immunohistochemistry were carried out. Myocardium metabolic evaluation by PET-CT showed that mean signal intensity (MSI) increased in these segments at week 4 compared with that at week 1 after BM-MSCs transplantation. Moreover, MRI demonstrated significant function enhancement in BM-MSCs group. The gene expressions of glucose transporters (GLUT1, GLUT4), glucose metabolism-related enzymes phosphofructokinase (PFK), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH)) and 70-kDa ribosomal protein S6 kinase (p70s6k) in BM-MSCs injected areas were up-regulated at week 4 after BM-MSCs transplantation and this was confirmed by Western-blot and immunohistochemistry. In conclusions, BM-MSCs transplantation could improve cardiac function in swine MI model by activation of mTOR signal transduction pathway. PMID:27321050

  2. Bone Marrow Mesenchymal Stem Cells (BM-MSCs) Improve Heart Function in Swine Myocardial Infarction Model through Paracrine Effects.

    PubMed

    Cai, Min; Shen, Rui; Song, Lei; Lu, Minjie; Wang, Jianguang; Zhao, Shihua; Tang, Yue; Meng, Xianmin; Li, Zongjin; He, Zuo-Xiang

    2016-01-01

    Stem cells are promising for the treatment of myocardial infarction (MI) and large animal models should be used to better understand the full spectrum of stem cell actions and preclinical evidences. In this study, bone marrow mesenchymal stem cells (BM-MSCs) were transplanted into swine heart ischemia model. To detect glucose metabolism in global left ventricular myocardium and regional myocardium, combined with assessment of cardiac function, positron emission tomography-computer tomography (PET-CT) and magnetic resonance imaging (MRI) were performed. To study the changes of glucose transporters and glucose metabolism-related enzymes and the signal transduction pathway, RT-PCR, Western-blot, and immunohistochemistry were carried out. Myocardium metabolic evaluation by PET-CT showed that mean signal intensity (MSI) increased in these segments at week 4 compared with that at week 1 after BM-MSCs transplantation. Moreover, MRI demonstrated significant function enhancement in BM-MSCs group. The gene expressions of glucose transporters (GLUT1, GLUT4), glucose metabolism-related enzymes phosphofructokinase (PFK), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH)) and 70-kDa ribosomal protein S6 kinase (p70s6k) in BM-MSCs injected areas were up-regulated at week 4 after BM-MSCs transplantation and this was confirmed by Western-blot and immunohistochemistry. In conclusions, BM-MSCs transplantation could improve cardiac function in swine MI model by activation of mTOR signal transduction pathway. PMID:27321050

  3. 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.

  4. Evaluation Model of Life Loss Due to Dam Failure

    NASA Astrophysics Data System (ADS)

    Huang, Dongjing

    2016-04-01

    Dam failure poses a serious threat to human life, however there is still lack of systematic research on life loss which due to dam failure in China. From the perspective of protecting human life, an evaluation model for life loss caused by dam failure is put forward. The model building gets three progressive steps. Twenty dam failure cases in China are preferably chosen as the basic data, considering geographical location and construction time of dams, as well as various conditions of dam failure. Then twelve impact factors of life loss are selected, including severity degree of flood, population at risk, understanding of dam failure, warning time, evacuation condition, number of damaged buildings, water temperature, reservoir storage, dam height, dam type, break time and distance from flood area to dam. And through principal component analysis, it gets four principal components consisting of the first flood character principle component, the second warning system principle component, the third human character principle component and the fourth space-time impact principle component. After multivariate nonlinear regression and ten-fold validation in combination, the evaluation model for life loss is finally established. And the result of the proposed model is closer to the true value and better in fitting effect in comparison with the results of RESCDAM method and M. Peng method. The proposed model is not only applied to evaluate life loss and its rate under various kinds of dam failure conditions in China, but also provides reliable cause analysis and prediction approach to reduce the risk of life loss.

  5. 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. PMID:26839324

  6. 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

  7. Repair of extrahepatic bile duct defect using a collagen patch in a Swine model.

    PubMed

    Tao, Liang; Li, Qiang; Ren, Haozhen; Chen, Bing; Hou, Xianglin; Mou, Lingjun; Zhou, Siqiao; Zhou, Jianxin; Sun, Xitai; Dai, Jianwu; Ding, Yitao

    2015-04-01

    Extrahepatic bile duct (EBD) injury can happen during surgery. To repair a defect of the EBD and prevent postoperative biliary complications, a collagen membrane was designed. The collagen material was porous, biocompatible, and degradable and could maintain its shape in bile soaking for about 4 weeks. The goal was to induce rapid bile duct tissue regeneration. Twenty Chinese experimental hybrid pigs were used in this study and divided into a patch group and a control group. A spindle-shaped defect (20 mm × 6 mm) was made in the anterior wall of the lower EBD in the swine model, and then the defect was reconstructed using a collagen patch with a drainage tube and wrapped with greater omentum. Ultrasound was performed at 2, 4, 8, and 12 weeks postoperatively. Liver function tests and white blood cell count (WBC) were measured. Hematoxylin-eosin staining, cytokeratin 7 immunohistochemical staining, and Van Gieson's staining of EBD were used. The diameter and thickness of the EBD at the graft site were measured. There was no significant difference in liver function tests or WBC in the patch group compared with the control group. No evidence of leakage or stricture was observed, but some pigs developed biliary sludge or stone at 4 and 8 weeks. The drainage tube was lost within 12 weeks. The neo-EBD could withstand normal biliary pressure 2 weeks after surgery. Histological study showed the accessory glands and epithelial cells gradually regenerated at graft sites from 4 weeks, with increasing vessel infiltration and decreasing inflammation. The collagen fibers became regular with full coverage of epithelial cells. The statistical analysis of diameter and thickness showed no stricture formation at the graft site, but the EBD wall was slightly thicker than in the normal bile duct due to collagen fiber deposition. The structure of the neo-EBD was similar to that of the normal EBD. The collagen membrane patch associated with a drainage tube and wrapped with greater

  8. 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.

  9. 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

  10. Reliability modeling and analysis of communication networks with dependent failures

    NASA Astrophysics Data System (ADS)

    Lam, Y. F.; Li, V. O. K.

    1986-01-01

    This paper presents a new model to study the reliability of communication networks in which link failures are statistically dependent. The approach tries to identify and model explicitly the events that cause communication link failures. No conditional probabilities are needed, and so two major difficulties inherent to them, namely, an exponential number of conditional probabilities to deal with and a consistency requirement to satisfy, are avoided. For reliability computations, some existing algorithms for finding network reliability can be used with minor modifications and no significant increase in computational complexity.

  11. Modeling the in-plane tension failure of composite plates

    SciTech Connect

    Trinh, K.V.

    1997-11-01

    This study developed a modeling method to predict the final failure load of laminated composite plates which may contain cutouts and are subjected to quasi-static in-plane tensile loads. This study focused on overcoming numerical problems often encountered in analyses that exhibit significant stable damage growth in the composite materials. To keep the computational cost at a reasonable level, the modeling method uses a quasi-static solution procedure to solve composite plate problems with quasi-static load. The numerical problems in the quasi-static analyses are nonconvergence problems caused by the discontinuous material behavior from brittle fiber failure. This study adds artificial damping to the material model to suppress the discontinuous material behavior. The artificial damping essentially changes the material behavior, and could adversely change the final failure load prediction. Thus, a selective scheme for adding the damping was developed to minimize adverse damping effects. In addition, this modeling method uses multiple analyses at different levels of artificial damping to determine damping effects on the failure load prediction. Fracture strength experimental data for small coupons with small cutouts and large panels with larger cutouts available in the literature were selected and used to verify failure predictions of the developed modeling method. Results show that, without the artificial damping treatment, progressive damage analyses reasonably predicted the fracture strength of the small coupons, but severely underpredicted the fracture strength of the large panels. With the artificial damping treatment, the analyses predicted the failure load of both the small coupons and the large panels reasonably well.

  12. Modeling failure for nonlinear strain paths with CrachFEM

    NASA Astrophysics Data System (ADS)

    Heath, A.; Gese, H.; Oberhofer, G.; Dell, H.

    2013-12-01

    This paper describes a general technique for simulating sheet failure under complex deformation. Separate failure risks are calculated for unstable necking and ductile fracture modes associated with void growth and shear banding. Necking is detected by a multi-scale method which considers sheet inhomogeneity, strain hardening, Bauschinger effects, strain rate sensitivity and the multi-axial stress-state in the neck. The model is easily calibrated from uniaxial test data and can be combined with a mesh-independent treatment of post-necking deformation. Ductile fracture risks are based on damage tensors calculated as integrals of the effective plastic strain weighted by the stress state. The tensorial formulation accounts for fracture strain recovery following load reversal. Model parameters can be evaluated with standard testing machines using tailored specimens. The failure methodology is realized in the software module MFGenYld+CrachFEM, which can be coupled to all major explicit FEM codes.

  13. 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.

  14. 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

  15. Intravascular Ultrasound Guidance for Transjugular Intrahepatic Portosystemic Shunt Procedure in a Swine Model

    SciTech Connect

    Kew, Jacqueline; Davies, Roger P.

    2004-01-15

    A new method is described for guiding hepato-portalvenous puncture using a longitudinal side-view intravascular ultrasound(L-IVUS) transducer to assist in the performance of transjugularintrahepatic portosystemic shunt (TIPS) in three Australian swine.Simultaneous L-IVUS with an AcuNav (registered) 5-10 MHz 10 Fr transducer(Acuson Corporation, Mountain View, CA, USA) and fluoroscopy guidance was used to image and monitor the hepatic to portal venous puncture,dilatation of the tract, and deployment of the TIPS stent. Flow through the shunt could be demonstrated with both L-IVUS and angiography. TIPS was successful in all swine. The time for portal vein puncture once the target portal vein was identified was reduced at each attempt. The number of portal vein puncture attempts was 2, 1, and 1. No post-procedural complication was evident. L-IVUS-guided TIPS is practical and has the potential to improve safety by permitting simultaneous ultrasound and fluoroscopic imaging of the needle and target vascular structures. This technique allows for a more streamlined approach to TIPS, decreasing the fluoroscopic time (hence,decreasing the radiation exposure to the staff and patient) and anesthetic time. In addition, there are improved safety benefits obviating the need for wedged portography, facilitating avoidance of bile duct and hepatic arterial puncture, and minimizing hepatic injury by decreasing liver capsular puncture and the attendant risks.

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

    PubMed Central

    2012-01-01

    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

  17. 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

  18. 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. PMID:25814248

  19. On predicting and modeling material failure under impact loading

    SciTech Connect

    Lewis, M.W.

    1998-09-01

    A method for predicting and modeling material failure in solids subjected to impact loading is outlined. The method uses classical void growth models of Gurson and Tvergaard in a material point method (MPM). Because of material softening, material stability is lost. At this point, the character of the governing partial differential equations changes, and localization occurs. This localization results in mesh dependence for many problems of interest. For many problems, predicting the occurrence of material failure and its extent is necessary. To enable this modeling, it is proposed that a discontinuity be introduced into the displacement field. By including a dissipation-based force-displacement relationship, the mesh dependence of energy dissipation can be avoided. Additionally, the material point method provides a means of allowing large deformations without mesh distortion or introduction of error through remapping.

  20. Product component genealogy modeling and field-failure prediction

    DOE PAGESBeta

    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

  1. The effect of combined treatment with Impella(®) and landiolol in a swine model of acute myocardial infarction.

    PubMed

    Yoshitake, Isamu; Hata, Mitsumasa; Sezai, Akira; Unosawa, Satoshi; Wakui, Shinji; Kimura, Haruka; Nakata, Kin-ichi; Hata, Hiroaki; Shiono, Motomi

    2012-09-01

    Cardiogenic shock is associated with a high mortality rate in patients with acute myocardial infarction (AMI). We developed a new treatment approach named heart rest therapy (HRT) for complete revascularization in the early stage of AMI using an ultra-short-acting β-blocker (landiolol) and an Impella(®) left ventricular assist device and verified the effect of this therapy in a swine model. In 18 male pigs, AMI was induced by left anterior descending coronary artery occlusion at the level of the second diagonal branch for 120 min, followed by 240 min of reperfusion. The animals were divided into three groups: group A had no support, group B was supported with the Impella(®), and group C was treated with HRT from 90 min after ischemia to 240 min after reperfusion. Infarct ratio (percentage of the infarct area relative to the area at infarct risk) was significantly reduced in group C (group A 65.38 ± 6.07, group B 39.66 ± 11.16, group C 21.78 ± 7.29), with a significant difference between groups A and B (P < 0.001), A and C (P < 0.001), and B and C (P = 0.006). Heart rates were significantly lower in group C at 30 min (P = 0.01), 60 min (P = 0.022), and 240 min (P = 0.032) after reperfusion compared with group B, without development of hypotension. HRT at the early stage in AMI stabilized the hemodynamic conditions and reduced infarct size and complications in a swine model. These results suggest that HRT can improve the prognosis of patients with AMI. PMID:22527977

  2. Intravenous Cobinamide Versus Hydroxocobalamin for Acute Treatment of Severe Cyanide Poisoning in a Swine (Sus scrofa) Model

    PubMed Central

    Bebarta, Lt Col Vikhyat S.; Tanen, David A.; Boudreau, Susan; Castaneda, Maria; Zarzabal, Lee A.; Vargas, Toni; Boss, Gerry R.

    2015-01-01

    Study objective Hydroxocobalamin is a Food and Drug Administration–approved antidote for cyanide poisoning. Cobinamide is a potential antidote that contains 2 cyanide-binding sites. To our knowledge, no study has directly compared hydroxocobalamin with cobinamide in a severe, cyanide-toxic large-animal model. Our objective is to compare the time to return of spontaneous breathing in swine with acute cyanide-induced apnea treated with intravenous hydroxocobalamin, intravenous cobinamide, or saline solution (control). Methods Thirty-three swine (45 to 55 kg) were intubated, anesthetized, and instrumented (continuous mean arterial pressure and cardiac output monitoring). Anesthesia was adjusted to allow spontaneous breathing with FiO2 of 21% during the experiment. Cyanide was continuously infused intravenously until apnea occurred and lasted for 1 minute (time zero). Animals were then randomly assigned to receive intravenous hydroxocobalamin (65 mg/kg), cobinamide (12.5 mg/kg), or saline solution and monitored for 60 minutes. A sample size of 11 animals per group was selected according to obtaining a power of 80%, an α of .05, and an SD of 0.17 in mean time to detect a 20% difference in time to spontaneous breathing. We assessed differences in time to death among groups, using Kaplan-Meier estimation methods, and compared serum lactate, blood pH, cardiac output, mean arterial pressure, respiratory rate, and minute ventilation time curves with repeated-measures ANOVA. Results Baseline weights and vital signs were similar among groups. The time to apnea and cyanide dose required to achieve apnea were similar. At time zero, mean cyanide blood and lactate concentrations and reduction in mean arterial pressure from baseline were similar. In the saline solution group, 2 of 11 animals survived compared with 10 of 11 in the hydroxocobalamin and cobinamide groups (P<.001 between the 2 treated groups and the saline solution group). Time to return of spontaneous breathing

  3. A damage model based on failure threshold weakening

    NASA Astrophysics Data System (ADS)

    Gran, Joseph D.; Rundle, John B.; Turcotte, Donald L.; Holliday, James R.; Klein, William

    2011-04-01

    A variety of studies have modeled the physics of material deformation and damage as examples of generalized phase transitions, involving either critical phenomena or spinodal nucleation. Here we study a model for frictional sliding with long-range interactions and recurrent damage that is parameterized by a process of damage and partial healing during sliding. We introduce a failure threshold weakening parameter into the cellular automaton slider-block model which allows blocks to fail at a reduced failure threshold for all subsequent failures during an event. We show that a critical point is reached beyond which the probability of a system-wide event scales with this weakening parameter. We provide a mapping to the percolation transition, and show that the values of the scaling exponents approach the values for mean-field percolation (spinodal nucleation) as lattice size L is increased for fixed R. We also examine the effect of the weakening parameter on the frequency-magnitude scaling relationship and the ergodic behavior of the model.

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

    PubMed Central

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

    2015-01-01

    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. PMID:25457602

  5. 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.

  6. Approach to failure in a discrete element model of the compressive failure of porous rocks (Invited)

    NASA Astrophysics Data System (ADS)

    Kun, F.; Varga, I.; Lennartz-Sassinek, S.; Main, I. G.

    2013-12-01

    We investigate how a porous rock sample approaches failure under uniaxial compression. Computer simulations are carried out in the framework of a discrete element model (DEM) which takes into account both the microstructure of the material and the dynamics of local fracturing, revealing much more detail and observation bandwidth in then granular mechanics than possible during standard laboratory tests. The synthetic sample is generated by sedimentation of randomly-sized spherical particles with a log-normal size distribution inside a cylindrical container. The cohesive interaction of particles is represented by beam elements that break when overstressed. The breaking rule takes into account both stretching and shear of particle contacts. When particles not connected by a beam come into contact their interaction is described by the Hertz contact law. The time evolution of the system is generated by molecular dynamics simulations in three dimensions. Computer simulations showed that under strain controlled uniaxial loading of the system micro-cracks initially nucleate in an uncorrelated way all over the sample. As loading proceeds localization occurs, i.e. the damage concentrates into a narrow damage band. Inside the damage band the material is crushed, into a poorly sorted mixture of fine powder and larger fragments with a power-law mass distribution, as observed in fault wear products (gouge) in natural and laboratory faults. Dynamic bursts of radiated energy, analogous to acoustic emissions observed in laboratory experiments, are identified as correlated trails of local fracture emerging as the consequence of stress redistribution. Characteristic quantities of burst such as size/rupture area, released elastic energy, and duration proved to have power law probability-size distributions over a broad range. The energy and duration of bursts have power law dependence on the rupture area created. As the system approaches macroscopic failure consecutive bursts become

  7. 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,…

  8. Failure Prediction in Fine Blanking Process with Stress Limit Model

    NASA Astrophysics Data System (ADS)

    Tong, Longchang; Manopulo, Niko; Hora, Pavel

    2010-06-01

    Extremely small blanking clearance and nearly sharp edges of blanking tool are the characteristics of fine blanking that produces near net shape parts. The extreme forming conditions make the failure prediction for fine blanking more difficult than for ordinary forming processes. Stress Limit Criterion (SLC) is adopted in this work to perform the failure prediction of 3D fine blanking process. In comparison with the stress triaxiality diagram, SLC is not sensitively affected by complex nonlinear deformation paths and can perform the task as well. However, the parameters that support the model have to be obtained with combination of dedicatedly designed experiments and numerical simulation. The FEM simulation must also be able to provide stable and reliable results.

  9. 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.

  10. 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

  11. 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.

  12. Bone marrow mesenchymal stem cells improve myocardial function in a swine model of acute myocardial infarction.

    PubMed

    Zhao, Jing-Jie; Liu, Xiao-Cheng; Kong, Feng; Qi, Tong-Gang; Cheng, Guang-Hui; Wang, Jue; Sun, Chao; Luan, Yun

    2014-09-01

    The aim of the current study was to confirm the effect and elucidate the mechanism of bone marrow mesenchymal stem cells (BMSCs) in acute myocardial infarction (AMI). AMI was induced in mini‑swine by ligating the left anterior descending coronary artery, and BMSCs (1x107) were injected via a sterile microinjection into the ischemic area. Six months postoperatively, electrocardiograph‑gated single photon emission computed tomography revealed that the myocardial filling defect was reduced and the left ventricular ejection fraction was improved in the BMSC group compared with the control group (P<0.05). Histopathological examination indicated that, in the BMSC treatment group, the percentage of survived myocardial tissue and the vessel density were increased, and the percentage of apoptosis was decreased compared with controls (P<0.05). Reverse transcription‑polymerase chain reaction results indicated that the expression levels of multiple inflammatory factors were significantly upregulated in the BMSC group compared with levels in the control group (P<0.05). In conclusion, the present study demonstrated that BMSC injection significantly improved cardiac function and reduced infarct size in six months, indicating that this method may be valuable for future study in clinical trials. PMID:25060678

  13. 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.

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

    PubMed Central

    O’Dea, Eamon B.; Snelson, Harry; Bansal, Shweta

    2016-01-01

    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. PMID:26947420

  15. Modeling materials failures for knowledge based system applications

    SciTech Connect

    Roberge, P.R.

    1996-12-31

    The evaluation of the probability of given premises to play a role in a final outcome can only be done when the parameters involved and their interactions are properly elucidated. But, for complex engineering situations, this often appears as an insurmountable task. The prediction of failures for the optimization of inspection and maintenance is such an example of complexity. After reviewing the models of expertise commonly used by knowledge engineers, this paper presents an object-oriented framework to guide the elicitation and organization of lifetime information for knowledge based system applications.

  16. Failure Behavior and Constitutive Model of Weakly Consolidated Soft Rock

    PubMed Central

    Wang, Wei-ming; Zhao, Zeng-hui; Wang, Yong-ji; Gao, Xin

    2013-01-01

    Mining areas in western China are mainly located in soft rock strata with poor bearing capacity. In order to make the deformation failure mechanism and strength behavior of weakly consolidated soft mudstone and coal rock hosted in Ili No. 4 mine of Xinjiang area clear, some uniaxial and triaxial compression tests were carried out according to the samples of rocks gathered in the studied area, respectively. Meanwhile, a damage constitutive model which considered the initial damage was established by introducing a damage variable and a correction coefficient. A linearization process method was introduced according to the characteristics of the fitting curve and experimental data. The results showed that samples under different moisture contents and confining pressures presented completely different failure mechanism. The given model could accurately describe the elastic and plastic yield characteristics as well as the strain softening behavior of collected samples at postpeak stage. Moreover, the model could precisely reflect the relationship between the elastic modulus and confining pressure at prepeak stage. PMID:24489511

  17. 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. PMID:23543462

  18. Mathematical modeling of flooding due to river bank failure

    NASA Astrophysics Data System (ADS)

    Viero, Daniele Pietro; D'Alpaos, Andrea; Carniello, Luca; Defina, Andrea

    2013-09-01

    Modeling of flooding events resulting from bank overflooding and levee breaching is of relevant social and environmental interest. Two-dimensional (2D) hydrodynamic models integrating the shallow water equations turn out to be very effective tools for the purpose at hand. Many of the available models also use 1D channel elements, fully coupled to the 2D model, to simulate the flow of small channels dissecting the urban and rural areas, and 1D elements, referred to as 1D-links, to efficiently model the flow over levees, road and rail embankments, bunds, the flow through control gates, either free or submerged, and the operation of other hydraulic structures. In this work we propose a physically-based 1D-link to model breach formation and evolution in fluvial levees, and levee failure due to either piping or overtopping. The proposed 1D-link is then embedded in a 1D-2D hydrodynamic model, thus accounting for critical feedbacks between breach formation and changes in the hydrodynamic flow field. The breach model also includes the possibility of simulating breach closure, an important feature particularly in the view of hydraulic risk assessment and management of the emergency. The model is applied to five different case studies and the results of the numerical simulations compare favorably with field observations displaying a good agreement in terms of urban and rural flooded areas, water levels within the channel, final breach widths, and water volumes flowed through the breach.

  19. Modeling Stakeholder/Value Dependency through Mean Failure Cost

    SciTech Connect

    Aissa, Anis Ben; Abercrombie, Robert K; Sheldon, Frederick T; Mili, Ali

    2010-01-01

    In an earlier series of works, Boehm et al. discuss the nature of information system dependability and highlight the variability of system dependability according to stakeholders. In a recent paper, the dependency patterns of this model are analyzed. In our recent works, we presented a stakeholder dependent quantitative security model, where we quantify security for a given stakeholder by the mean of the loss incurred by the stakeholder as a result of security threats. We show how this mean can be derived from the security threat configuration (represented as a vector of probabilities that reflect the likelihood of occurrence of the various security threats). We refer to our security metric as MFC, for Mean Failure Cost. In this paper, we analyze Boehm's model from the standpoint of the proposed metric, and show whether, to what extent, and how our metric addresses the issues raised by Boehm's Stakeholder/Value definition of system dependability.

  20. Microstructural modeling of heterogeneous failure modes in martensitic steels

    NASA Astrophysics Data System (ADS)

    Hatem, Tarek Moustafa

    A three-dimensional multiple-slip dislocation-density-based crystalline formulation, specialized finite-element formulations, predictive failure models, and infinity-power integrable function based Voronoi tessellations adapted to martensitic orientations, were used to investigate large strain inelastic deformation, dislocation-density evolution in martensitic transformation, and heterogeneous failure modes in martensitic microstructures. The formulation is based on accounting for variant morphologies and orientations, secondary phases, such as retained austenite and inclusions, and initial dislocations-densities that are uniquely inherent to martensitic microstructures. The computational framework and the constitutive formulation were validated with experimental results for 10% Ni high-strength steel alloy. Furthermore, the formulation was used to investigate microstructures mapped directly from SEM/EBSD images of martensitic steel alloys. The interrelated effects of microstructural characteristics, such as parent austenite orientation, variants distribution and arrangement, retained austenite, inclusions, initial dislocation-density, and defects, such as microcracks, and microvoids, were investigated for different failure modes such as rupture, transgranular and intergranular fracture, and shear localization over a broad spectrum of loading conditions that range from quasi-static to high strain-rate conditions. The computational predictions, consistent with experimental observations, indicated that variant morphology and orientations have a direct consequence on how shear-strain accumulation and failure evolves in martensitic microstructures subjected to quasi-static and high strain-rate loading conditions. The analysis shows that shear-strain localization occurs due to slip-system compatibilities corresponding to low-angle blocks boundaries, the loading direction and the long direction of laths, which result in shear-pipes. At specific triple junctions, rotation

  1. 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

  2. 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)

  3. Modeling hydrogen sulfide emissions across the gas-liquid interface of an anaerobic swine waste treatment storage system

    NASA Astrophysics Data System (ADS)

    Blunden, Jessica; Aneja, Viney P.; Overton, John H.

    Hydrogen sulfide (H 2S) is a colorless gas emitted during decomposition of hog manure that produces an offensive "rotten egg" smell and is considered a toxic manure gas. In the southeastern United States, anaerobic waste treatment lagoons are widely used to store and treat hog excreta at commercial hog farms. Hydrogen sulfide is produced as manure decomposes anaerobically, resulting from the mineralization of organic sulfur compounds as well as the reduction of oxidized inorganic sulfur compounds by sulfur-reducing bacteria. The process of H 2S emissions from anaerobic waste treatment lagoons are investigated utilizing a two-film model with three different modeling approaches: Coupled Mass Transfer with Chemical Reactions Model with the assumption (1) pH remains constant in the liquid film (MTCR Model I) and (2) pH may change throughout the liquid film due to diffusion processes that occur within the film (MTCR Model II); and (3) a Mass Transfer Model which neglects chemical reactions (MTNCR Model) in the gas and liquid films. Results of model predictions are consistent with previous works, which show that flux is largely dependent on the physicochemical lagoon properties including sulfide concentration, pH, and lagoon temperature. Air temperature and low wind velocities (e.g., <3.25 m s -1) have negligible impact on flux. Results also indicate that flux values decrease with increased film thickness. The flux was primarily influenced by variations in the liquid film thickness, signifying that the H 2S flux is driven by liquid-phase parameters. Model results were compared with H 2S flux measurements made at a swine waste treatment storage lagoon in North Carolina using a dynamic emission flux chamber system in order to evaluate model accuracy in calculating lagoon H 2S emissions. The MTCR Model II predicted the highest increase in emission rates as aqueous sulfide concentration was increased. The MTNCR Model showed the highest dependence on pH. All three models

  4. 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.

  5. 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

  6. 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.

  7. An Integrated Approach to Modeling and Mitigating SOFC Failure

    SciTech Connect

    Fedorov, A.; Haynes, C.; Qu, J.

    2005-01-27

    The objective of this project is to develop first-order failure criteria to be used for the initial design, material selection and optimization against thermomechanical failure of the PEN structure in high temperature SOFCs.

  8. 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.

  9. Spinal Cord Tolerance to Reirradiation with Single-Fraction Radiosurgery: A Swine Model

    PubMed Central

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

    2011-01-01

    Purpose This study was performed to determine the spinal cord tolerance of swine to single-fraction, partial-volume irradiation one year after uniform irradiation to 30Gy in 10 fractions. Materials/ Methods A 10cm length of spinal cord (C3-T1) was uniformly irradiated to 30Gy in ten consecutive fractions and reirradiated one year later with a single radiosurgery dose centered within the previously irradiated segment. Radiosurgery was delivered to a cylindrical volume approximately 5cm in length and 2cm 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. Twenty-three pigs were stratified into six dose groups with mean maximum spinal cord doses of 14.9±0.1 (n=2), 17.1±0.3 (n=3), 19.0±0.1 (n=5), 21.2±0.1 (n=5), 23.4±0.2 (n=5), and 25.4±0.4 (n=3)Gy. The mean percentage spinal cord volumes receiving >=10Gy 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 determined by a change in gait during a one year follow-up period. Results A steep dose-response curve was observed with an ED50(95% CI) for the maximum point dose of 19.7Gy (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 the gray matter. Histologic comparison with a companion study of de novo irradiated animals revealed retreatment responders have more extensive tissue damage, including infarction of the gray matter, only at prescription doses >20Gy. Conclusion Pigs receiving spinal radiosurgery one year following 30Gy in 10 fractions are not at significantly higher risk of developing motor deficits than pigs that have received radiosurgery alone. PMID:22197239

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. Accelerated failure time model under general biased sampling scheme.

    PubMed

    Kim, Jane Paik; Sit, Tony; Ying, Zhiliang

    2016-07-01

    Right-censored time-to-event data are sometimes observed from a (sub)cohort of patients whose survival times can be subject to outcome-dependent sampling schemes. In this paper, we propose a unified estimation method for semiparametric accelerated failure time models under general biased estimating schemes. The proposed estimator of the regression covariates is developed upon a bias-offsetting weighting scheme and is proved to be consistent and asymptotically normally distributed. Large sample properties for the estimator are also derived. Using rank-based monotone estimating functions for the regression parameters, we find that the estimating equations can be easily solved via convex optimization. The methods are confirmed through simulations and illustrated by application to real datasets on various sampling schemes including length-bias sampling, the case-cohort design and its variants. PMID:26941240

  15. Code System for the Analysis of Component Failure Data with a Compound Statistical Model.

    Energy Science and Technology Software Center (ESTSC)

    2000-08-22

    Version 00 Two separate but similar Fortran computer codes have been developed for the analysis of component failure data with a compound statistical model: SAFE-D and SAFE-R. The SAFE-D code (Statistical Analysis for Failure Estimation-failure-on-Demand) analyzes data which give the observed number of failures (failure to respond properly) in a specified number of demands for several similar components that should change their condition upon demand. The second program, SAFE-R (Statistical Analysis for Failure Estimation-failure Rate)more » is to be used to analyze normally operating components for which the observed number of failures in a specified operating time is given. In both these codes the failure parameter (failure probability per demand for SAFE-D or failure rate for SAFE-R) may be assumed equal for all similar components (the homogeneous failure model) or may be assumed to be a random variable distributed among similar components according to a prior distribution (the heterogeneous or compound failure model). Related information can be found at the developer's web site: http://www.mne.ksu.edu/~jks/.« less

  16. 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. PMID:27241205

  17. 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.

  18. Causes of growth failure in growth failure in a model of neonatal zinc (Zn) deficiency

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Zn deficiency is a common cause of growth failure in children in developing countrie,s and Zn supplementation can significantly improve growth of at-risk populations. Although Zn deficiency leads to anorexia and poor growth, it is unclear whether anorexia is the sole cause of poor growth. Our object...

  19. Numerical investigations of rib fracture failure models in different dynamic loading conditions.

    PubMed

    Wang, Fang; Yang, Jikuang; Miller, Karol; Li, Guibing; Joldes, Grand R; Doyle, Barry; Wittek, Adam

    2016-01-01

    Rib fracture is one of the most common thoracic injuries in vehicle traffic accidents that can result in fatalities associated with seriously injured internal organs. A failure model is critical when modelling rib fracture to predict such injuries. Different rib failure models have been proposed in prediction of thorax injuries. However, the biofidelity of the fracture failure models when varying the loading conditions and the effects of a rib fracture failure model on prediction of thoracic injuries have been studied only to a limited extent. Therefore, this study aimed to investigate the effects of three rib failure models on prediction of thoracic injuries using a previously validated finite element model of the human thorax. The performance and biofidelity of each rib failure model were first evaluated by modelling rib responses to different loading conditions in two experimental configurations: (1) the three-point bending on the specimen taken from rib and (2) the anterior-posterior dynamic loading to an entire bony part of the rib. Furthermore, the simulation of the rib failure behaviour in the frontal impact to an entire thorax was conducted at varying velocities and the effects of the failure models were analysed with respect to the severity of rib cage damages. Simulation results demonstrated that the responses of the thorax model are similar to the general trends of the rib fracture responses reported in the experimental literature. However, they also indicated that the accuracy of the rib fracture prediction using a given failure model varies for different loading conditions. PMID:26214136

  20. 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.

  1. 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

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

    PubMed

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

    2015-10-01

    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 ((13)C)-labeled substrates ([2-(13)C]lactate, [5,6,7-(13)C3]heptanoate, and [U-(13)C6]leucine) were systemically infused as metabolic markers for the final 60 min before left ventricular tissue extraction. Extracted tissues were analyzed for the (13)C-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

  3. 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.

  4. Effects of condensed organic matter on PCBs bioavailability in juvenile swine, an animal model for young children.

    PubMed

    Delannoy, Matthieu; Rychen, Guido; Fournier, Agnès; Jondreville, Catherine; Feidt, Cyril

    2014-06-01

    The exposure assessment of polychlorinated biphenyls (PCBs) contaminated soils is a critical issue in terms of human health, especially since little reliable information on transfer of PCBs to humans via involuntary soil ingestion is available. Indeed, young children with their hand-to-mouth activity may be exposed to contaminated soils. The current study addresses the impact of soil organic matter (OM) condensation on bioavailability of sequestrated NDL-PCBs. Three artificial soils (ASs) were prepared according to OECD guideline 207. One standard soil (SS), devoid of OM, and two amended versions of this SS with fulvic acid (FA) or activated carbon (AC) were prepared to obtain 1% organic mass. This study involved fourteen juvenile male swine as a digestive physiology model of young children. Animals were randomly distributed into 4 contaminated groups (3 replicates) and a control one (2 replicates). During 10d, the piglets were fed AS or a corn oil spiked with 19200 ng of Aroclor 1254 per g of dry matter (6000 ng g(-1) of NDL-PCBs) to achieve an exposure dose of 1200 ng NDL-PCBskg(-1) of body weight per day. After 10d of oral exposure, NDL-PCBs in adipose tissue, liver and muscles were analyzed by GC-MS, after extraction and purification. Two distinct groups of treatments were found: on the one hand oil, SS and FA, on the other hand C and AC. This study highlights that condensed OM (AC) strongly reduces bioavailability whereas the less condensed one (FA) does not seem to have a significant effect. This result has to be considered as a first major step for further relative bioavailability studies involving mixture of different humic substances. PMID:24289980

  5. Transcatheter closure of membranous ventricular septal defects with a new nitinol prosthesis in a natural swine model.

    PubMed

    Gu, X; Han, Y M; Titus, J L; Amin, Z; Berry, J M; Kong, H; Rickers, C; Urness, M; Bass, J L

    2000-08-01

    Transcatheter closure of a membranous ventricular septal defect (MVSD) is much more difficult than closure of other intracardiac defects because of the proximity to the aortic and tricuspid valves and their relatively large size in small children. In this report, transcatheter closure of naturally occurring membranous VSDs was attempted in 12 Yucatan minipigs. The prosthesis is constructed from fine Nitinol wires in the shape of two buttons and a connecting waist filled with polyester fiber. Two kinds of prosthesis were used in this study: concentric and eccentric left-sided retention disks. A 6 or 7 Fr delivery sheath was advanced across the membranous VSD over a wire from femoral vein. The prosthesis was inserted through the sheath by pushing the delivery cable to deploy a button into left ventricle and the second button was then deployed into right ventricle by withdrawing the sheath. Successful implantation of the device was achieved in all animals except one. Complete closure rate was 58.3% immediately after placement, 100% at 1 week, 90.9% at 1 month and 3 months, and 100% at 6 months. An associated aneurysm of the membranous septum increased significantly in size in two of three animals using the concentric device, and in none of the animals using the eccentric device. A trace to mild aortic regurgitation was present in two of the three animals using the concentric device, and only in one of the eight animals using the eccentric device. Five animals developed a trace to mild tricuspid regurgitation. Pathologic examination showed all devices to be covered by smooth neoendothelium at 3 months. This report presents the first experimental study where closure of membranous ventricular septal defects in a swine model was attempted by specially constructed devices. Procedural success and occlusion rates are very encouraging but overall results cannot equal surgery. Further experimentation is needed with devices that are redesigned according to the experience gained

  6. The rat as a model for evaluation of biotin bioavailability from feed ingredients for poultry and swine.

    PubMed

    Misir, R

    1987-01-01

    Biotin bioavailability from poultry and swine feed ingredients was determined in an experiment involving growing rats (55-60 g body weight, initially), housed individually in stainless steel cages with raised metal floors. The rats were fed a biotin-free diet fortified with egg-white powder for 7 d prior to being put on test. Thereafter, 5 rats were randomly assigned to each of the experimental diets, as follows: a basal egg white-free diet (A) without added biotin, or supplemented with graded levels of d-biotin, i.e., 0.05, 0.10, 0.25, 0.50 and 1.00 microgram/g, and also 12 test diets prepared by incorporating various cereal grains and/or two protein supplements into diet A by partial replacement of casein and carbohydrates. The experimental diets were fed ad libitum for 21 d, and met or exceeded recommended levels for all nutrients except biotin. Results showed significant correlations between pairs of parameters, including plasma biotin vs biotin intake (P less than 0.01), liver biotin vs biotin intake (P less than 0.05) and plasma biotin vs liver biotin (P less than 0.01). The bioavailable biotin from test ingredients was estimated using the derived regression equation, Y = 0.54X + 1.05, (r = 0.85), where X = biotin intake (microgram/d) and Y = plasma biotin (ng/ml). In most cases, these values were greater than the corresponding biotin intakes, indicating that intestinal biotin synthesis and coprophagy might be increasing the supply of bioavailable biotin to the rats. Therefore, the rat might not be a good model animal for routine evaluation of biotin bioavailability from feed ingredients.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3583596

  7. 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

  8. 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.

  9. 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...

  10. 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). PMID:19215189

  11. Modeling root reinforcement using root-failure Weibull survival function

    NASA Astrophysics Data System (ADS)

    Schwarz, M.; Giadrossich, F.; Cohen, D.

    2013-03-01

    Root networks contribute to slope stability through complicated interactions that include mechanical compression and tension. Due to the spatial heterogeneity of root distribution and the dynamic of root turnover, the quantification of root reinforcement on steep slope is challenging and consequently the calculation of slope stability as well. Although the considerable advances in root reinforcement modeling, some important aspect remain neglected. In this study we address in particular to the role of root strength variability on the mechanical behaviors of a root bundle. Many factors may contribute to the variability of root mechanical properties even considering a single class of diameter. This work presents a new approach for quantifying root reinforcement that considers the variability of mechanical properties of each root diameter class. Using the data of laboratory tensile tests and field pullout tests, we calibrate the parameters of the Weibull survival function to implement the variability of root strength in a numerical model for the calculation of root reinforcement (RBMw). The results show that, for both laboratory and field datasets, the parameters of the Weibull distribution may be considered constant with the exponent equal to 2 and the normalized failure displacement equal to 1. Moreover, the results show that the variability of root strength in each root diameter class has a major influence on the behavior of a root bundle with important implications when considering different approaches in slope stability calculation. Sensitivity analysis shows that the calibration of the tensile force and the elasticity of the roots are the most important equations, as well as the root distribution. The new model allows the characterization of root reinforcement in terms of maximum pullout force, stiffness, and energy. Moreover, it simplifies the implementation of root reinforcement in slope stability models. The realistic quantification of root reinforcement for

  12. 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.

  13. Oxidative and pre-inflammatory stress in wedge resection of pulmonary parenchyma using the radiofrequency ablation technique in a swine model

    PubMed Central

    2012-01-01

    Background Radiofrequency ablation (RFA) is a thermal energy delivery system used for coagulative cellular destruction of small tumors through percutaneous or intraoperative application of its needle electrode to the target area, and for assisting partial resection of liver and kidney. We tried to evaluate the regional oxidative and pre-inflammatory stress of RFA-assisted wedge lung resection, by measuring the MDA and tumor Necrosis Factor Alpha (TNF-α) concentration in the resected lung tissue of a swine model. Method Fourteen white male swines, divided in two groups, the RFA-group and the control group (C-group) underwent a small left thoracotomy and wedge lung resection of the lingula. The wedge resection in the RFA-group was performed using the RFA technique whereas in C-group the simple "cut and sew" method was performed. We measured the malondialdehyde (MDA) and TNF-α concentration in the resected lung tissue of both groups. Results In C-group the MDA mean deviation rate was 113 ± 42.6 whereas in RFA-group the MDA mean deviation rate was significantly higher 353 ± 184 (p = 0.006). A statistically significant increase in TNF-α levels was also observed in the RFA-group (5.25 ± 1.36) compared to C-group (mean ± SD = 8.48 ± 2.82) (p = 0.006). Conclusion Our data indicate that RFA-assisted wedge lung resection in a swine model increases regional MDA and TNF-a factors affecting by this oxidative and pre-inflammatory stress of the procedure. Although RFA-assisted liver resection can be well tolerated in humans, the possible use of this method to the lung has to be further investigated in terms of regional and systemic reactions and the feasibility of performing larger lung resections. PMID:22260184

  14. Self-Propelled Dressings Containing Thrombin and Tranexamic Acid Improve Short-Term Survival in a Swine Model of Lethal Junctional Hemorrhage.

    PubMed

    Baylis, James R; St John, Alexander E; Wang, Xu; Lim, Esther B; Statz, Matthew L; Chien, Diana; Simonson, Eric; Stern, Susan A; Liggins, Richard T; White, Nathan J; Kastrup, Christian J

    2016-09-01

    Hemorrhage is the leading cause of preventable death in trauma, and hemorrhage from noncompressible junctional anatomic sites is particularly difficult to control. The current standard is QuikClot Combat Gauze packing, which requires 3 min of compression. We have created a novel dressing with calcium carbonate microparticles that can disperse and self-propel upstream against flowing blood. We loaded these microparticles with thrombin and tranexamic acid and tested their efficacy in a swine arterial bleeding model without wound compression. Anesthetized immature female swine received 5 mm femoral arteriotomies to induce severe junctional hemorrhage. Wounds were packed with kaolin-based QuikClot Combat Gauze (KG), propelled thrombin-microparticles with protonated tranexamic acid (PTG), or a non-propelling formulation of the same thrombin-microparticles with non-protonated tranexamic acid (NPTG). Wounds were not compressed after packing. Each animal then received one 15 mL/kg bolus of hydroxyethyl starch solution followed by Lactated Ringer as needed for hypotension (maximum: 100 mL/kg) for up to 3 h. Survival was improved with PTG (3-h survival: 8/8, 100%) compared with KG (3/8, 37.5%) and NPTG (2/8, 25%) (P <0.01). PTG animals maintained lower serum lactate and higher hemoglobin concentrations than NPTG (P <0.05) suggesting PTG decreased severity of subsequent hemorrhagic shock. However, total blood loss, Lactated Ringer infusion volumes, and mean arterial pressures of surviving animals were not different between groups (P >0.05). Thus, in this swine model of junctional arterial hemorrhage, gauze with self-propelled, prothrombotic microparticles improved survival and 2 indicators of hemorrhagic shock when applied without compression, suggesting this capability may enable better treatment of non-compressible junctional wounds. PMID:27206277

  15. 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....

  16. 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.

  17. 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.

  18. 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

  19. Minimally Invasive Swine Experimental Model for the In Vivo Study of Liver Metabolism of Drugs

    PubMed Central

    Piazza, O; Romano, R; Scarpati, G; Esposito, C; Cavaglià, E; Corona, M

    2012-01-01

    Purpose To develop a clinically relevant porcine model for the study of hepatic metabolism of drugs by means of hepatic vein catheterization. Materials and Methods: review of literature and elaboration of a hypothesis, design of an experimental method. Results: recent clinical studies were conducted by withdrawing cirrhotic patients’ blood from right hepatic vein during hepatic vein pressure gradient measurements. Basing on our personal clinical experience and evaluation of research needs, an experimental model is proposed. Conclusions: contemporary measurement of peripheral and hepatic concentration of drugs by peripheral vein and hepatic vein catheterization can be used to create a reliable and reproducible porcine model to study liver metabolism of drugs in vivo. PMID:23905064

  20. Smoothed particle hydrodynamics modelling for failure in metals

    NASA Astrophysics Data System (ADS)

    Strand, Russell K.

    It is generally regarded to be a difficult task to model multiple fractures leading to fragmentation in metals subjected to high strain rates using numerical methods. Meshless methods such as Smoothed Particle Hydrodynamics (SPH) are well suited to the application of fracture mechanics, since they are not prone to the problems associated with mesh tangling. This research demonstrates and validates a numerical inter-particle fracture model for the initiation, growth and subsequent failure in metals at high strain rate, applicable within a Total Lagrangian SPH scheme. Total Lagrangian SPH performs calculations in the reference state of a material and therefore the neighbourhoods remain fixed throughout the computation; this allows the inter-particle bonds to be stored and tracked as material history parameters. Swegle (2000) showed that the SPH momentum equation can be rearranged in terms of a particle-particle interaction area. By reducing this area to zero via an inter-particle damage parameter, the principles of continuum damage mechanics can be observed without the need for an effective stress term, held at the individual particles.. This research makes use of the Cochran-Banner damage growth model which has been updated for 3D damage and makes the appropriate modifications for inter-particle damage growth. The fracture model was tested on simulations of a 1D flyer plate impact test and the results were compared to experimental data. Some limited modelling was also conducted in 2 and 3 dimensions and promising results were observed. Research was also performed into the mesh sensitivity of the explosively driven Mock- Holt experiment. 3D simulations using the Eulerian SPH formulation were conducted and the best results were observed with a radial packing arrangement. An in-depth assessment of the Monaghan repulsive force correction was also conducted in attempt to eliminate the presence of the SPH tensile instability and stabilise the available Eulerian SPH code

  1. 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. PMID:24895072

  2. 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.

  3. 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 ...

  4. The Suitability of Swine as Models for Humans to Assess the Effect of Nutrition on Immunity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is generally accepted that the pig is a good model for human nutritional studies. Much less is known about the relative similarities between the two species in terms of the immune response. A literature and laboratory-based analysis was conducted comparing 185 parameters associated with g...

  5. 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.

  6. 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

  7. Heterogeneous Microinfarcts Caused by Coronary Microemboli: Evaluation with Multidetector CT and MR Imaging in a Swine Model1

    PubMed Central

    Saloner, David; Martin, Alastair J.; Ursell, Philip C.; Saeed, Maythem

    2010-01-01

    Purpose: To directly compare the sensitivity of 64-section multidetector computed tomography (CT) with that of 1.5-T magnetic resonance (MR) imaging in the depiction and measurement of heterogeneous 7–8-week-old microinfarcts and the quantification of regional left ventricular (LV) function and perfusion in the territory of coronary intervention in a swine model. Materials and Methods: Approval was obtained from the institutional animal committee. An x-ray/MR system was used to catheterize the left anterior descending (LAD) coronary artery with x-ray guidance and to delineate the perfusion territory. The vessel was selectively microembolized in six pigs with small-diameter embolic material (40–120 µm, 250000 count). At 7–8 weeks after microembolization, multidetector CT and MR imaging were used to assess LV function, first-pass perfusion, and delayed contrast enhancement in remote myocardium and microinfarct scars. Histochemical staining with triphenyltetrazolium chloride (TTC) was used to confirm and quantify heterogeneous microinfarct scars. The two-tailed Wilcoxon signed rank test was used to detect differences between modalities and myocardial regions. Results: The LAD territory was 32.4% ± 3.8(stadard error of the mean) of the LV mass. Multidetector CT and MR imaging have similar sensitivity in the detection of regional and global LV dysfunction and extent of microinfarct. The mean LV end-diastolic volume, end-systolic volume, and ejection fraction were 93 mL ± 8, 46 mL ± 4, and 50% ± 3, respectively, on multidetector CT images and 92 mL ± 8, 48 mL ± 5, and 48% ± 3, respectively, on MR images (P ≥ .05). The extent of heterogeneous microinfarct was not significantly different between multidetector CT (6.3% ± 0.8 of the LV mass), MR imaging (6.6% ± 0.5 of the LV mass), and TTC staining (7.0% ± 0.6 of the LV mass). First-pass multidetector CT and MR imaging demonstrated significant regional differences (P < .05) in time to peak between the

  8. Predictive modelling of fatigue failure in concentrated lubricated contacts.

    PubMed

    Evans, H P; Snidle, R W; Sharif, K J; Bryant, M J

    2012-01-01

    Reducing frictional losses in response to the energy agenda will require use of less viscous lubricants causing hydrodynamically-lubricated bearings to operate with thinner films leading to "mixed lubrication" conditions in which a degree of direct interaction occurs between surfaces protected only by boundary tribofilms. The paper considers the consequences of thinner films and mixed lubrication for concentrated contacts such as those occurring between the teeth of power transmission gears and in rolling element bearings. Surface fatigue in gears remains a serious problem in demanding applications, and its solution will become more pressing with the tendency towards thinner oils. The particular form of failure examined here is micropitting, which is identified as a fatigue phenomenon occurring at the scale of the surface roughness asperities. It has emerged recently as a systemic difficulty in the operation of large scale wind turbines where it occurs in both power transmission gears and their support bearings. Predictive physical modelling of these contacts requires a transient mixed lubrication analysis for conditions in which the predicted lubricant film thickness is of the same order or significantly less than the height of surface roughness features. Numerical solvers have therefore been developed which are able to deal with situations in which transient solid contacts occur between surface asperity features under realistic engineering conditions. Results of the analysis, which reveal the detailed time-varying behaviour of pressure and film clearance, have been used to predict fatigue and damage accumulation at the scale of surface asperity features with the aim of improving understanding of the micropitting phenomenon. The possible consequences on fatigue of residual stress fields resulting from plastic deformation of surface asperities is also considered. PMID:23285624

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

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Swine from regions where swine... SWINE FEVER, CLASSICAL SWINE FEVER, SWINE VESICULAR DISEASE, AND BOVINE SPONGIFORM ENCEPHALOPATHY: PROHIBITED AND RESTRICTED IMPORTATIONS § 94.14 Swine from regions where swine vesicular disease...

  11. 9 CFR 94.14 - Swine from regions where swine vesicular disease exists; importations prohibited.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Swine from regions where swine... SWINE FEVER, CLASSICAL SWINE FEVER, SWINE VESICULAR DISEASE, AND BOVINE SPONGIFORM ENCEPHALOPATHY: PROHIBITED AND RESTRICTED IMPORTATIONS § 94.14 Swine from regions where swine vesicular disease...

  12. 9 CFR 94.14 - Swine from regions where swine vesicular disease exists; importations prohibited.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Swine from regions where swine... SWINE FEVER, CLASSICAL SWINE FEVER, SWINE VESICULAR DISEASE, AND BOVINE SPONGIFORM ENCEPHALOPATHY: PROHIBITED AND RESTRICTED IMPORTATIONS § 94.14 Swine from regions where swine vesicular disease...

  13. 9 CFR 94.14 - Swine from regions where swine vesicular disease exists; importations prohibited.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Swine from regions where swine... SWINE FEVER, CLASSICAL SWINE FEVER, SWINE VESICULAR DISEASE, AND BOVINE SPONGIFORM ENCEPHALOPATHY: PROHIBITED AND RESTRICTED IMPORTATIONS § 94.14 Swine from regions where swine vesicular disease...

  14. Evolution of Coronary Flow in an Experimental Slow Flow Model in Swines: Angiographic and Pathological Insights

    PubMed Central

    Bai, Yupeng; Hu, Liqun; Yu, Delong; Peng, Sheng; Liu, Xiaogang; Zhang, Mingjing; Gu, Ye

    2015-01-01

    Objective. Pathomechanism of coronary slow flow phenomenon remains largely unclear now. Present study observed the pathological and angiographic evolution in a pig model of coronary slow flow. Methods. Coronary slow flow was induced by repeat coronary injection of small doses of 40 µm microspheres in 18 male domestic pigs and angiographic and pathological changes were determined at 3 hours, 7 days, and 28 days after microspheres injection. Results. Compared to control group treated with coronary saline injection (n = 6) and baseline level, coronary flow was significantly reduced at 3 hours and 7 days but completely recovered at 28 days after coronary microsphere injection in slow flow group. Despite normal coronary flow at 28 days after microsphere injection, enhanced myocardial cytokine expression, left ventricular dysfunction, adverse remodelling, and ischemia/microembolism related pathological changes still persisted or even progressed from 3 hours to 28 days after coronary microsphere injection. Conclusions. Our results show that this large animal slow flow model could partly reflect the chronic angiographic, hemodynamic, and pathological changes of coronary slow flow and could be used to test new therapy strategies against the slow flow phenomenon. PMID:26539516

  15. 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

  16. 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...

  17. A model for the extended studies of hepatic hemodynamics and metabolism in swine.

    PubMed

    Drougas, J G; Barnard, S E; Wright, J K; Sika, M; Lopez, R R; Stokes, K A; Williams, P E; Pinson, C W

    1996-12-01

    To our knowledge postoperative hepatic hemodynamics and hepatic metabolism have not been fully studied on a long-term basis. Our goal was to develop a large animal model that would permit the measurement of hepatic blood flow (BF), perihepatic pressures (P), and hepatic metabolism in a long-term setting. Catheters were inserted into the jugular vein, carotid artery, pulmonary artery, hepatic vein, and portal vein (PV) of 27 commercially bred pigs; ultrasonic transit time flowmeter probes were placed around the hepatic artery and PV. Daily postoperative measurements of jugular vein P, carotid artery P, pulmonary artery P, hepatic vein P, and PVP, as well as hepatic artery BF and PVBF, were recorded for 20 days. Hepatic carbohydrate metabolism was assessed by arteriovenous difference techniques. Jugular vein P, pulmonary artery P, hepatic vein P, PVP, and heart rate reached steady-state values during the first week, with a mean +/- SEM of 1.0 +/- 0.3 mm Hg for jugular vein P, 21.4 +/- 2.1 mm Hg for pulmonary artery P, 4.3 +/- 0.4 mm Hg for HVP, 7.8 +/- 0.5 mm Hg for PVP, and 116 +/- 4 beats per minute for heart rate. Mean carotid artery P increased from 65 +/- 3 mm Hg during surgery to 94 +/- 2 mm Hg on postoperative day 1 (P < 0.001) and to a mean 101 +/- 2 mm Hg thereafter. Total hepatic BF reached a steady-state value of 1,132 +/- 187 ml/min by postoperative day 7 (P = 0.19). Over week 1 hepatic artery BF measured as a percentage of total hepatic BF decreased from 35.0 +/- 3.0% to 15.5 +/- 2.7%, and PVBF increased from 65.0 +/- 3.0% to 84.5 +/- 2.7% (P < 0.005); both variables were steady thereafter. In the hemodynamic steady state the net hepatic balances of glucose, lactate, glycerol, and alanine in 5 pigs were 9.9 +/- 4.0, -4.2 +/- 0.4, -2.3 +/- 1.1, and -0.68 +/- 0.22 micromol/kg per min respectively. The net gut (portal-drained viscera) balances of glucose, lactate, alanine, and glycerol were -2.0 +/- 2.5, 1.1 +/- 0.5, 0.73 +/- 0.18, and -0.69 +/- 0

  18. Plan on test to failure of a prestressed concrete containment vessel model

    SciTech Connect

    Takumi, K.; Nonaka, A.; Umeki, K.; Nagata, K.; Soejima, M.; Yamaura, Y.; Costello, J.F.; von Riesemann, W.A.; Parks, M.B.; Horschel, D.S.

    1992-07-01

    A summary of the plans to test a prestressed concrete containment vessel (PCCV) model to failure is provided in this paper. The test will be conducted as a part of a joint research program between the Nuclear Power Engineering Corporation (NUPEC), the United States Nuclear Regulatory Commission (NRC), and Sandia National Laboratories (SNL). The containment model will be a scaled representation of a PCCV for a pressurized water reactor (PWR). During the test, the model will be slowly pressurized internally until failure of the containment pressure boundary occurs. The objectives of the test are to measure the failure pressure, to observe the mode of failure, and to record the containment structural response up to failure. Pre- and posttest analyses will be conducted to forecast and evaluate the test results. Based on these results, a validated method for evaluating the structural behavior of an actual PWR PCCV will be developed. The concepts to design the PCCV model are also described in the paper.

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

    PubMed Central

    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 (Cmax), time to reach Cmax (Tmax), and area under the curve (AUC), were determined in plasma and ileum content. The Cmax, Tmax, 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 Cmax, Tmax, 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 Emax (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. PMID:26870006

  20. 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.

  1. 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.

  2. 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.

  3. Anti‐Remodeling and Anti‐Fibrotic Effects of the Neuregulin‐1β Glial Growth Factor 2 in a Large Animal Model of Heart Failure

    PubMed Central

    Galindo, Cristi L.; Kasasbeh, Ehab; Murphy, Abigail; Ryzhov, Sergey; Lenihan, Sean; Ahmad, Farhaan A.; Williams, Philip; Nunnally, Amy; Adcock, Jamie; Song, Yanna; Harrell, Frank E.; Tran, Truc‐Linh; Parry, Tom J.; Iaci, Jen; Ganguly, Anindita; Feoktistov, Igor; Stephenson, Matthew K.; Caggiano, Anthony O.; Sawyer, Douglas B.; Cleator, John H.

    2014-01-01

    Background Neuregulin‐1β (NRG‐1β) is a growth factor critical for cardiac development and repair with therapeutic potential for heart failure. We previously showed that the glial growth factor 2 (GGF2) isoform of NRG‐1β improves cardiac function in rodents after myocardial infarction (MI), but its efficacy in a large animal model of cardiac injury has not been examined. We therefore sought to examine the effects of GGF2 on ventricular remodeling, cardiac function, and global transcription in post‐MI swine, as well as potential mechanisms for anti‐remodeling effects. Methods and Results MI was induced in anesthetized swine (n=23) by intracoronary balloon occlusion. At 1 week post‐MI, survivors (n=13) received GGF2 treatment (intravenous, biweekly for 4 weeks; n=8) or were untreated (n=5). At 5 weeks post‐MI, fractional shortening was higher (32.8% versus 25.3%, P=0.019), and left ventricular (LV) end‐diastolic dimension lower (4.5 versus 5.3 cm, P=0.003) in GGF2‐treated animals. Treatment altered expression of 528 genes, as measured by microarrays, including collagens, basal lamina components, and matricellular proteins. GGF2‐treated pigs exhibited improvements in LV cardiomyocyte mitochondria and intercalated disk structures and showed less fibrosis, altered matrix structure, and fewer myofibroblasts (myoFbs), based on trichrome staining, electron microscopy, and immunostaining. In vitro experiments with isolated murine and rat cardiac fibroblasts demonstrate that NRG‐1β reduces myoFbs, and suppresses TGFβ‐induced phospho‐SMAD3 as well as αSMA expression. Conclusions These results suggest that GGF2/NRG‐1β prevents adverse remodeling after injury in part via anti‐fibrotic effects in the heart. PMID:25341890

  4. 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.

  5. 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...

  6. Zebrafish Heart Failure Models for the Evaluation of Chemical Probes and Drugs

    PubMed Central

    Monte, Aaron; Cook, James M.; Kabir, Mohd Shahjahan; Peterson, Karl P.

    2013-01-01

    Abstract Heart failure is a complex disease that involves genetic, environmental, and physiological factors. As a result, current medication and treatment for heart failure produces limited efficacy, and better medication is in demand. Although mammalian models exist, simple and low-cost models will be more beneficial for drug discovery and mechanistic studies of heart failure. We previously reported that aristolochic acid (AA) caused cardiac defects in zebrafish embryos that resemble heart failure. Here, we showed that cardiac troponin T and atrial natriuretic peptide were expressed at significantly higher levels in AA-treated embryos, presumably due to cardiac hypertrophy. In addition, several human heart failure drugs could moderately attenuate the AA-induced heart failure by 10%–40%, further verifying the model for drug discovery. We then developed a drug screening assay using the AA-treated zebrafish embryos and identified three compounds. Mitogen-activated protein kinase kinase inhibitor (MEK-I), an inhibitor for the MEK-1/2 known to be involved in cardiac hypertrophy and heart failure, showed nearly 60% heart failure attenuation. C25, a chalcone derivative, and A11, a phenolic compound, showed around 80% and 90% attenuation, respectively. Time course experiments revealed that, to obtain 50% efficacy, these compounds were required within different hours of AA treatment. Furthermore, quantitative polymerase chain reaction showed that C25, not MEK-I or A11, strongly suppressed inflammation. Finally, C25 and MEK-I, but not A11, could also rescue the doxorubicin-induced heart failure in zebrafish embryos. In summary, we have established two tractable heart failure models for drug discovery and three potential drugs have been identified that seem to attenuate heart failure by different mechanisms. PMID:24351044

  7. 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.

  8. 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.

  9. Statistical failure models for water distribution pipes - A review from a unified perspective.

    PubMed

    Scheidegger, Andreas; Leitão, João P; Scholten, Lisa

    2015-10-15

    This review describes and compares statistical failure models for water distribution pipes in a systematic way and from a unified perspective. The way the comparison is structured provides the information needed by scientists and practitioners to choose a suitable failure model for their specific needs. The models are presented in a novel framework consisting of: 1) Clarification of model assumptions. The models originally formulated in different mathematical forms are all presented as failure rate. This enables to see differences and similarities across the models. Furthermore, we present a new conceptual failure rate that an optimal model would represent and to which the failure rate of each model can be compared. 2) Specification of the detailed data assumptions required for unbiased model calibration covering the structure and completeness of the data. 3) Presentation of the different types of probabilistic predictions available for each model. Nine different models and their variations or further developments are presented in this review. For every model an overview of its applications published in scientific journals and the available software implementations is provided. The unified view provides guidance to model selection. Furthermore, the model comparison presented herein enables to identify areas where further research is needed. PMID:26162313

  10. Absence of Gal epitope prolongs survival of swine lungs in an ex vivo model of hyperacute rejection

    PubMed Central

    Nguyen, Bao-Ngoc H.; Azimzadeh, Agnes M.; Schroeder, Carsten; Buddensick, Thomas; Zhang, Tianshu; Laaris, Amal; Cochrane, Megan; Schuurman, Henk-Jan; Sachs, David H.; Allan, James S.; Pierson, Richard N.

    2012-01-01

    Background Galactosyl transferase gene knock-out (GalTKO) swine offer a unique tool to evaluate the role of the Gal antigen in xenogenic lung hyperacute rejection. Methods We perfused GalTKO miniature swine lungs with human blood. Results were compared with those from previous studies using wild-type and human decay-accelerating factor-transgenic (hDAF+/+) pig lungs. Results GalTKO lungs survived 132 ± 52 min compared to 10 ± 9 min for wild-type lungs (P = 0.001) and 45 ± 60 min for hDAF+/+ lungs (P = 0.18). GalTKO lungs displayed stable physiologic flow and pulmonary vascular resistance (PVR) until shortly before graft demise, similar to autologous perfusion, and unlike wild-type or hDAF+/+ lungs. Early (15 and 60 min) complement (C3a) and platelet activation and intrapulmonary platelet deposition were significantly diminished in GalTKO lungs relative to wild-type or hDAF+/+ lungs. However, GalTKO lungs adsorbed cytotoxic anti-non-Gal antibody and elaborated high levels of thrombin; their demise was associated with increased PVR, capillary congestion, intravascular thrombi and strong CD41 deposition not seen at earlier time points. Conclusions In summary, GalTKO lungs are substantially protected from injury but, in addition to anti-non-Gal antibody and complement, platelet adhesion and non-physiologic intravascular coagulation contribute to Gal-independent lung injury mechanisms. PMID:21496117

  11. Meniscus maturation in the swine model: changes occurring along with anterior to posterior and medial to lateral aspect during growth.

    PubMed

    Di Giancamillo, Alessia; Deponti, Daniela; Addis, Alessandro; Domeneghini, Cinzia; Peretti, Giuseppe M

    2014-10-01

    The meniscus plays important roles in knee function and mechanics and is characterized by a heterogeneous matrix composition. The changes in meniscus vascularization observed during growth suggest that the tissue-specific composition may be the result of a maturation process. This study has the aim to characterize the structural and biochemical variations that occur in the swine meniscus with age. To this purpose, menisci were collected from young and adult pigs and divided into different zones. In study 1, both lateral and medial menisci were divided into the anterior horn, the body and the posterior horn for the evaluation of glycosaminoglycans (GAGs), collagen 1 and 2 content. In study 2, the menisci were sectioned into the inner, the intermediate and the outer zones to determine the variations in the cell phenotype along with the inner-outer direction, through gene expression analysis. According to the results, the swine meniscus is characterized by an increasing enrichment in the cartilaginous component with age, with an increasing deposition in the anterior horn (GAGs and collagen 2; P < 0.01 both); moreover, this cartilaginous matrix strongly increases in the inner avascular and intermediate zone, as a consequence of a specific differentiation of meniscal cells towards a cartilaginous phenotype (collagen 2, P < 0.01). The obtained data add new information on the changes that accompany meniscus maturation, suggesting a specific response of meniscal cells to the regional mechanical stimuli in the knee joint. PMID:25216283

  12. 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

  13. 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

  14. 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

  15. 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

  16. Environmental enhancement of swine lagoons through influent treatment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Confined swine production generates large volumes of wastewater typically stored and treated in anaerobic lagoons. Failure of these lagoons during tropical storms in North Carolina along with major public environmental concerns led to a permanent state moratorium of construction of new anaerobic lag...

  17. 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...

  18. 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

  19. The effect of the perfluorocarbon emulsion Oxycyte on platelet count and function in the treatment of decompression sickness in a swine model.

    PubMed

    Cronin, William A; Senese, Angela L; Arnaud, Francoise G; Regis, David P; Auker, Charles R; Mahon, Richard T

    2016-09-01

    Decompression from elevated ambient pressure is associated with platelet activation and decreased platelet counts. Standard treatment for decompression sickness (DCS) is hyperbaric oxygen therapy. Intravenous perfluorocarbon (PFC) emulsion is a nonrecompressive therapy being examined that improves mortality in animal models of DCS. However, PFC emulsions are associated with a decreased platelet count. We used a swine model of DCS to study the effect of PFC therapy on platelet count, function, and hemostasis. Castrated male swine (n = 50) were fitted with a vascular port, recovered, randomized, and compressed to 180 feet of sea water (fsw) for 31 min followed by decompression at 30 fsw/min. Animals were observed for DCS, administered 100% oxygen, and treated with either emulsified PFC Oxycyte (DCS-PFC) or isotonic saline (DCS-NS). Controls underwent the same procedures, but were not compressed (Sham-PFC and Sham-NS). Measurements of platelet count, thromboelastometry, and coagulation were obtained 1 h before compression and 1, 24, 48, 96, 168 and 192 h after treatment. No significant changes in normalized platelet counts were observed. Prothrombin time was elevated in DCS-PFC from 48 to 192 h compared with DCS-NS, and from 96 to 192 h compared with Sham-PFC. Normalized activated partial thromboplastin time was also elevated in DCS-PFC from 168 to 192 h compared with Sham-PFC. No bleeding events were noted. DCS treated with PFC (Oxycyte) does not impact platelet numbers, whole blood clotting by thromboelastometry, or clinical bleeding. Late changes in prothrombin time and activated partial thromboplastin time associated with PFC use in both DCS therapy and controls warrant further investigation. PMID:26650458

  20. Modelling the failure precursor mechanism of lamellar fibrous tissues, example of the annulus fibrosus.

    PubMed

    Mengoni, Marlène; Jones, Alison C; Wilcox, Ruth K

    2016-10-01

    The aims of this study were to assess the damage and failure strengths of lamellar fibrous tissues, such as the anterior annulus fibrosus (AF), and to develop a mathematical model of damage propagation of the lamellae and inter-lamellar connections. This level of modelling is needed to accurately predict the effect of damage and failure induced by trauma or clinical interventions. 26 ovine anterior AF cuboid specimens from 11 lumbar intervertebral discs were tested in radial tension and mechanical parameters defining damage and failure were extracted from the in-vitro data. Equivalent 1D analytical models were developed to represent the specimen strength and the damage propagation, accounting for the specimen dimensions and number of lamellae. Model parameters were calibrated on the in-vitro data. Similar to stiffness values reported for other orientations, the outer annulus was found stronger than the inner annulus in the radial direction, with failure at higher stress values. The inner annulus failed more progressively, showing macroscopic failure at a higher strain value. The 1D analytical model of damage showed that lamellar damage is predominant in the failure mechanism of the AF. The analytical model of the connections between lamellae allowed us to represent separately damage processes in the lamellae and the inter-lamellar connections, which cannot be experimentally tested individually. PMID:27442918

  1. 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

  2. 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. PMID:23386974

  3. 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

  4. 9 CFR 94.14 - Swine from regions where swine vesicular disease exists; importations prohibited.

    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 swine... 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...

  5. 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

  6. Modeling of self-healing against cascading overload failures in complex networks

    NASA Astrophysics Data System (ADS)

    Liu, Chaoran; Li, Daqing; Fu, Bowen; Yang, Shunkun; Wang, Yunpeng; Lu, Guangquan

    2014-09-01

    The development of online prognostic and fast-recovery technology promotes the realization of self-healing techniques. Considering the cascading overload failures as one of the major failure modes in real networks, we introduce a model for self-healing against overload propagation in complex networks due to malicious attack. Especially, we study the role of basic quantities (restoration timing and resource) in general self-healing restoration against cascading overload failures in network models of homogeneous (Erdős-Rényi) and heterogeneous (scale-free) networks. We demonstrate how networks during cascading failures can be saved from the brink of collapse by proper combination of both restoration timing and resource. And we find that optimal restoration timing for the model and realistic networks exists at a given restoration resource in the self-healing process.

  7. 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.

  8. 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

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

    2015-01-01

    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 (MV) 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 seven consecutive days. We derived the circadian (total variance explained by rhythms of τ between 20 and 28 h)/ultradian (total variance explained by rhythms of τ between 1 and <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 and 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 MV. PMID:26204131

  9. Comparison of Noninvasive pH and Blood Lactate as Predictors of Mortality in a Swine Hemorrhagic Shock with Restricted Volume Resuscitation Model

    PubMed Central

    Soller, Babs; Zou, Fengmei; Prince, M. Dale; Dubick, Michael A.; Sondeen, Jill L.

    2015-01-01

    ABSTRACT Recent clinical studies have demonstrated that high blood lactate in the prehospital setting and poor lactate clearance in the emergency department are predictive of in-hospital mortality. This analysis of data collected from a swine model of hemorrhage and restricted volume resuscitation investigated the hypotheses that noninvasive muscle pH (pHm) and H+ clearance would predict mortality, and the responses would be similar between pHm and lactate. Data from a set of 57 swine were analyzed over the first 2 h after controlled hemorrhage and uncontrolled splenic bleeding. Surviving animals were ones that lived for the full 5-h experimental period. Venous lactate was determined at baseline, shock, and at 30, 60, and 120 min after injury. Spectra were collected continuously from the posterior thigh using a prototype CareGuide 1100 Oximeter and pHm calculated from the spectra; H+ concentration was determined from pHm. Lactate clearance rate was calculated from the difference in lactate concentration at 120 min and shock, and H+ clearance was calculated in a similar manner. Comparison of the area under the receiver operator characteristic curves was used to assess prediction of survival at 5 h after injury. At 120 min after injury, lactate, lactate clearance, noninvasive pHm, and noninvasive H+ clearance were equivalent predictors of mortality each with a receiver operator characteristic area under the curve of 0.87. Thresholds for single lactate (<3.8 mmol/L) or pHm (>7.30) determinations were found to be consistent with a resuscitation goal targeted to reverse acidosis. Continuous, noninvasive pHm monitoring may provide a substitute for lactate measurement in trauma patients, particularly in the prehospital and emergency department settings. PMID:25526374

  10. 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

  11. Mechanistic Considerations Used in the Development of the PROFIT PCI Failure Model

    SciTech Connect

    Pankaskie, P. J.

    1980-05-01

    A fuel Pellet-Zircaloy Cladding (thermo-mechanical-chemical) Interactions (PC!) failure model for estimating the probability of failure in !ransient increases in power (PROFIT) was developed. PROFIT is based on 1) standard statistical methods applied to available PC! fuel failure data and 2) a mechanistic analysis of the environmental and strain-rate-dependent stress versus strain characteristics of Zircaloy cladding. The statistical analysis of fuel failures attributable to PCI suggested that parameters in addition to power, transient increase in power, and burnup are needed to define PCI fuel failures in terms of probability estimates with known confidence limits. The PROFIT model, therefore, introduces an environmental and strain-rate dependent strain energy absorption to failure (SEAF) concept to account for the stress versus strain anomalies attributable to interstitial-disloction interaction effects in the Zircaloy cladding. Assuming that the power ramping rate is the operating corollary of strain-rate in the Zircaloy cladding, then the variables of first order importance in the PCI fuel failure phenomenon are postulated to be: 1. pre-transient fuel rod power, P{sub I}, 2. transient increase in fuel rod power, {Delta}P, 3. fuel burnup, Bu, and 4. the constitutive material property of the Zircaloy cladding, SEAF.

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

    PubMed

    Adachi, Yasumoto; Makita, Kohei

    2015-09-01

    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

  13. 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

  14. 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

  15. 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.

  16. Modeling of failure and response to laminated composites subjected to in-plane loads

    NASA Technical Reports Server (NTRS)

    Shahid, Iqbal; Chang, Fu-Kuo

    1993-01-01

    An analytical model was developed for predicting the response of laminated composites with or without a cutout and subjected to in-plane tensile and shear loads. Material damage resulting from the loads in terms of matrix cracking, fiber-matrix shearing, and fiber breakage was considered in the model. Delamination, an out-of-plane failure mode, was excluded from the model.

  17. 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...

  18. Effect of ultrasonic treatment on swine wastewater solubilization.

    PubMed

    Lee, Y H; Kim, S-M; Na, S; So, K-H; Nam, J-J

    2009-01-01

    In order to accelerate hydrolysis known to be the rate-limiting step of the overall digestion process for swine wastewater, an ultrasonic treatment process was tested for the solubilization of the swine wastewater. The effectiveness of ultrasonic solubilization of the swine wastewater under various operational conditions was compared by means of an increment of soluble organics in the treated swine wastewater and the hydrolysis rate constant. Ultrasonic treatment resulted in the high degree of solubilization of particulate organics in the swine wastewater and the degree of solubilization increased with increasing supplied energy. The highest extent of an increment of SCOD concentration and SCOD/TCOD ratio at the end of the operation time of 60 min was 109.7 and 117.5%, respectively, under 120 W power output and 20(o)C operating temperature conditions. The observed highest hydrolysis rate constant described by pseudo-first order rate constant was 2.94 h(-1) under the same conditions. Based on the estimated activation energy from modeling using the Arrhenius equation, ultrasonic solubilization of the swine wastewater under higher supplied energy conditions was more dependent on the operating temperature, which was consistent with the experimentally obtained results. Based on the investigation into the effect of gas type and gas delivery methods for ultrasonic solubilization of the swine wastewater, oxygen gas bubbling through the liquid showed the highest degree of an increment of soluble organics possibly attributed to the influent of oxygen in an increase of radicals during the sonolysis. PMID:19214016

  19. Histomorphometric comparison of the human, swine, and ovine collecting systems.

    PubMed

    Simões, Michele; de Souza, Diogo B; Gallo, Carla B M; Pereira-Sampaio, Marco A; Costa, Waldemar S; Sampaio, Francisco J

    2016-07-01

    The ovine kidney has been recently determined to be a better model than the swine kidney for the study of collecting system healing after partial nephrectomy. However, there is no histological study comparing the collecting systems of these species. To compare human, swine, and ovine collecting systems using histomorphometry. The collecting systems of 10 kidneys from each species (human, swine, and ovine) were processed for histomorphometry. The thickness of the three layers (mucosal connective tissue, submucosal muscular, and adventitial connective tissue) were measured. The densities of smooth muscle fibers, elastic system fibers, and cells were also measured. Additionally, blood vessel density in the adventitial connective tissue was measured. Analysis of the collecting systems from the three species presented several differences. The adventitial connective tissue from the swine samples was thicker, with more blood vessels and smooth muscle fibers, compared with that from the human and ovine samples. Swine also had higher density of elastic fibers on the submucosal muscular layer. Ovine and human collecting systems shared several similar features, such as blood vessel and elastic fiber density in all layers and the density of cellular and muscular fibers in the submucosal muscular and adventitial connective tissue layers. The collecting system of the ovine kidney is more similar to that of the human kidney compared with that of the swine kidney. This may explain the differences between the healing mechanisms in swine and those in humans and sheep after partial nephrectomy. Anat Rec, 299:967-972, 2016. © 2016 Wiley Periodicals, Inc. PMID:27111677

  20. 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…

  1. 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...

  2. Swine Influenza Update

    Technology Transfer Automated Retrieval System (TEKTRAN)

    On April 24, 2009, the Centers for Disease Control (CDC) confirmed an influenza epidemic was occurring in people and the genetic lineage was most closely related to influenza viruses known to be circulating in swine. The outbreak epicenter appeared to be in central Mexico and the virus spread to th...

  3. Failure of all-ceramic fixed partial dentures in vitro and in vivo: analysis and modeling.

    PubMed

    Kelly, J R; Tesk, J A; Sorensen, J A

    1995-06-01

    Hertzian cone cracks visible at the loading site of 20 all-ceramic fixed partial dentures (FPDs), tested in vitro, led to the hypotheses that failure was due to the propagation of localized contact damage crack systems (Hertzian stress state) and that such damage was an unlikely clinical failure mode. Fractographic analysis of the 20 laboratory-failed and nine clinically-failed all-ceramic FPDs allowed for definitive testing of these hypotheses and a comparison between in vitro and in vivo failure behavior. In all cases, failure occurred in the FPD connectors (none from contact damage), with approximately 70 to 78% originating from the interface between the core and veneer ceramics. The coincidence between failure origins provides strong evidence that the in vitro test modeled aspects of structural behavior having clinical importance. The fractographic observations, coupled with the in vitro failure load data, furnished very specific boundary conditions which were applied to constrain mathematical models of FPD connector failure. Finite element analysis (FEA) of the laboratory FPDs found that maximum principal tensile stresses would occur at locations consistent with the fractographic observations only if: (1) there were appropriate elastic moduli differences between the ceramics; and (2) a small amount of abutment rotation was allowed. Weibull failure probability (Pf) calculations, incorporating FEA stress profiles, very closely replicated the laboratory failure distribution only when: (1) the veneer ceramic was much weaker than the core ceramic; and (2) the Weibull modulus of the core-veneer interface was much lower than that for the free veneer surface (i.e., the interface is of lower quality with regard to defects).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7629333

  4. 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

  5. Damage Model and Progressive Failure Analyses for Filament Wound Composite Laminates

    NASA Astrophysics Data System (ADS)

    Ribeiro, Marcelo Leite; Vandepitte, Dirk; Tita, Volnei

    2013-10-01

    Recent improvements in manufacturing processes and materials properties associated with excellent mechanical characteristics and low weight have made composite materials very attractive for application on civil aircraft structures. However, even new designs are still very conservative, because the composite failure phenomenon is very complex. Several failure criteria and theories have been developed to describe the damage process and how it evolves, but the solution of the problem is still open. Moreover, modern filament winding techniques have been used to produce a wide variety of structural shapes not only cylindrical parts, but also “flat” laminates. Therefore, this work presents the development of a damage model and its application to simulate the progressive failure of flat composite laminates made using a filament winding process. The damage model was implemented as a UMAT (User Material Subroutine), in ABAQUSTM Finite Element (FE) framework. Progressive failure analyses were carried out using FE simulation in order to simulate the failure of flat filament wound composite structures under different loading conditions. In addition, experimental tests were performed in order to identify parameters related to the material model, as well as to evaluate both the potential and the limitations of the model. The difference between numerical and the average experimental results in a four point bending set-up is only 1.6 % at maximum load amplitude. Another important issue is that the model parameters are not so complicated to be identified. This characteristic makes this model very attractive to be applied in an industrial environment.

  6. Aftershocks in a time-to-failure slider-block model

    NASA Astrophysics Data System (ADS)

    Gran, J. D.; Rundle, J. B.; Turcotte, D. L.

    2011-12-01

    Several earthquake models have been used to study the mechanisms that lead to a Gutenberg-Richter distribution of earthquake magnitudes. One such model is the cellular automaton (CA) slider-block model. Events (earthquakes) in this model are initiated by a loader plate increasing stress uniformly on all blocks until a single block reaches a static friction failure threshold which can trigger a cascade of failures of blocks. This model, although useful, misses a key part of the earthquake process, i.e. aftershocks. Aftershocks occur within a short time period following the main-shock and are due to stress redistributions within the earth's crust rather than movement of the interacting tectonic plates. We describe here a modified version of CA slider-block model, which includes a time-to-failure mode, that allows blocks to fail below the static threshold value if enough time passes. This new feature allows multiple independent events to occur during a single plate update. We measure time in Monte Carlo steps and have tested various functions for the time-to-failure to understand the connection between the time-to-failure and Omori's law for the frequency of aftershocks following the main-shock. After each loader plate update, we see a main-shock followed in time by multiple aftershocks that decay in magnitude. We believe this to be another mechanism for the occurrence of aftershocks in addition to that found by Dietrich, JGR(1994).

  7. 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.

  8. The Bama miniature swine is susceptible to experimental HEV infection.

    PubMed

    Tang, Zi-Min; Wang, Si-Ling; Ying, Dong; Wen, Gui-Ping; Cai, Wei; Zhang, Ke; Ji, Wen-Fang; Yang, Ming; Zheng, Zi-Zheng; Xia, Ning-Shao

    2016-01-01

    The hepatitis E virus (HEV) is one of the main causes of enterically transmitted hepatitis worldwide. Although the mortality rates associated with HEV are generally low, they can be up to 28% in HEV-infected pregnant women, and the elderly are more susceptible. The reasons for this selective severity are unclear, partially because there is no suitable, easy-to-use model in which to study HEV infection. Non-human primates and standard swine have been identified as being sensitive to infection with HEV and have been used for HEV infection studies. However, studies in these animals have been limited by high housing costs and the difficulty of manipulating these animals. In the current study, we established a model of HEV infection using Bama miniature swine. The model is easy to use and is sensitive to infections with HEV genotypes 3 and 4, which are classified as zoonotic HEVs. In this model, infection of Bama miniature swine with HEV genotypes 3 and 4 caused the typical features. All Bama miniature swine that were infected with HEV genotypes 3 and 4 exhibited significant HEV viremia, shedding, anti-HEV antibody responses and partial liver inflammation. Bama miniature swine may serve as an alternative to standard swine models for the study of zoonotic HEV infection and HEV genotype specificity research. PMID:27534702

  9. The Bama miniature swine is susceptible to experimental HEV infection

    PubMed Central

    Tang, Zi-Min; Wang, Si-Ling; Ying, Dong; Wen, Gui-Ping; Cai, Wei; Zhang, Ke; Ji, Wen-Fang; Yang, Ming; Zheng, Zi-Zheng; Xia, Ning-Shao

    2016-01-01

    The hepatitis E virus (HEV) is one of the main causes of enterically transmitted hepatitis worldwide. Although the mortality rates associated with HEV are generally low, they can be up to 28% in HEV-infected pregnant women, and the elderly are more susceptible. The reasons for this selective severity are unclear, partially because there is no suitable, easy-to-use model in which to study HEV infection. Non-human primates and standard swine have been identified as being sensitive to infection with HEV and have been used for HEV infection studies. However, studies in these animals have been limited by high housing costs and the difficulty of manipulating these animals. In the current study, we established a model of HEV infection using Bama miniature swine. The model is easy to use and is sensitive to infections with HEV genotypes 3 and 4, which are classified as zoonotic HEVs. In this model, infection of Bama miniature swine with HEV genotypes 3 and 4 caused the typical features. All Bama miniature swine that were infected with HEV genotypes 3 and 4 exhibited significant HEV viremia, shedding, anti-HEV antibody responses and partial liver inflammation. Bama miniature swine may serve as an alternative to standard swine models for the study of zoonotic HEV infection and HEV genotype specificity research. PMID:27534702

  10. 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.

  11. Simple Elasticity Modeling and Failure Prediction for Composite Flexbeams

    NASA Technical Reports Server (NTRS)

    Makeev, Andrew; Armanios, Erian; OBrien, T. Kevin (Technical Monitor)

    2001-01-01

    A simple 2D boundary element analysis, suitable for developing cost effective models for tapered composite laminates, is presented. Constant stress and displacement elements are used. Closed-form fundamental solutions are derived. Numerical results are provided for several configurations to illustrate the accuracy of the model.

  12. 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.

  13. Mechanics of progressive failures leading to rapid shallow landslides using the fiber bundle model

    NASA Astrophysics Data System (ADS)

    Cohen, Denis; Schwarz, Massimiliano; Or, Dani

    2010-05-01

    Shallow landslides are often sudden events caused by the rapid failure of a slip surface. Yet, such global failure is the culmination of a series of steps that begin with the initiation and growth of local cracks and failure planes that, with increased load eventually coalesce to form a continuous surface. The dynamics of such failure events is controlled, in part, by the rate of soil weakening during water infiltration and by distribution of tree roots that span across these failure zones. Conventional approaches rely on static limit-equilibrium analysis to compute the ratio of soil resistive strength to gravitational driving forces (factor of safety) to determine slope stability, often ignoring dynamics leading to failure as well as heterogeneities associated with land cover, subsurface material properties, hydrologic pathways, and presence of biological elements such as roots. Casting the problem in terms of stable or unstable slope does not describe the progressive formation of cracks in heterogeneous soils or the failure of roots that stretch across tension cracks or basal shear planes. Here we use the fiber bundle model (FBM) to describe soil and root failure focusing on landslide initiation. The FBM consists of a bundle of parallel, elastic-brittle fibers of identical length and stiffness stretched quasi-statically between two plates. Heterogeneity is introduced by fibers having finite threshold strength drawn randomly from a probability density function. Step-loading of the bundle causes weak fibers to break and load redistribution (either global or local) among surviving fibers can trigger secondary, tertiary, and so on, failures, a process known as an avalanche. We illustrate the potential utility of the FBM for two cases: (1) modeling of lateral root reinforcement where fibers represent roots of different sizes and strengths, and (2) modeling of progressive weakening of soils by water infiltration where fibers are analogs of bonds between soil aggregates

  14. 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.

  15. A review of failure models for ceramic matrix composite laminates 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.

  16. LOCAL BUCKLEY-JAMES ESTIMATION FOR HETEROSCEDASTIC ACCELERATED FAILURE TIME MODEL

    PubMed Central

    Pang, Lei; Lu, Wenbin; Wang, Huixia Judy

    2016-01-01

    In survival analysis, the accelerated failure time model is a useful alternative to the popular Cox proportional hazards model due to its easy interpretation. Current estimation methods for the accelerated failure time model mostly assume independent and identically distributed random errors, but in many applications the conditional variance of log survival times depend on covariates exhibiting some form of heteroscedasticity. In this paper, we develop a local Buckley-James estimator for the accelerated failure time model with heteroscedastic errors. We establish the consistency and asymptotic normality of the proposed estimator and propose a resampling approach for inference. Simulations demonstrate that the proposed method is flexible and leads to more efficient estimation when heteroscedasticity is present. The value of the proposed method is further assessed by the analysis of a breast cancer data set.

  17. 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.

  18. 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

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

    PubMed

    Ponnaluri, Aditya V S; Perotti, Luigi E; Liu, Michael; Qu, Zhilin; Weiss, James N; Ennis, Daniel B; Klug, William S; Garfinkel, Alan

    2016-06-01

    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

  20. Modeling and numerical simulation of the progressive failure of pultruded fiber-reinforced plastic structures

    NASA Astrophysics Data System (ADS)

    Yin, Jianshen

    Fiber reinforced plastic pultruded (FRP) materials generally fail in a brittle manner. After first failure, a small increment of applied load can cause the failure to propagate to neighboring regions in the material and seriously reduce the load carrying capacity of the FRP structure. Two methods are being developed to model progressive failure of solid structures by the finite element method. One method is based on reduction of the stiffness components of failed elements. The other is based on node/element separation so that the failure configuration of the structure can be simulated. The latter one is more appropriate to large scales of failures. This method has been applied mainly in explicit finite element codes. In an explicit code, which is appropriate to transient dynamic problems, the solution is at element level at each time step. No global stiffness matrix is needed. In an implicit code, which is appropriate for static or quasi-static problems, the global stiffness matrix must be assembled at each time step. The geometrical configuration of the finite element model at failure changes the global stiffness matrix. Therefore, implementing the node separation method in an implicit code is more difficult than in an explicit code. Although efforts have been made to model static failure problems with explicit codes using dynamic relaxation, the results of these tests have been disappointing. The computational methods for progressive failures of statics problems will need to rely on implicit codes. This thesis presents a methodology for implementing the node/element separation method in an implicit code. Numerical strategies such as constrained node pairs with failure, releasing constraints and regenerating node-variable relations, are proposed to accomplish this task. The modifications to the general implicit time procedure due to the inclusion of this method are investigated in detail. NIKE3D, a 3-D implicit finite element code, was employed to test this method

  1. 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.

  2. 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…

  3. 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…

  4. Investigating the Effects of Resveratrol on Chronically Ischemic Myocardium in a Swine Model of Metabolic Syndrome: A Proteomics Analysis

    PubMed Central

    Sabe, Ashraf A.; Sadek, Ahmed A.; Elmadhun, Nassrene Y.; Dalal, Rahul S.; Robich, Michael P.; Bianchi, Cesario

    2015-01-01

    Abstract Resveratrol has been shown to improve cardiac perfusion and ventricular function after chronic ischemic injury. Using proteomic analysis, we sought to objectively investigate potential mechanisms, by which resveratrol exerts its cardioprotective effects in the setting of metabolic syndrome and chronic myocardial ischemia. Yorkshire swine were divided into two groups based on diet: high cholesterol (n=7) or a high-cholesterol diet with supplemental resveratrol (n=6). Four weeks later, all animals underwent surgical placement of an ameroid constrictor to their left circumflex artery. Diets were continued for another 7 weeks, and then the ischemic myocardium was harvested for proteomics analysis. Proteomic analysis identified 669 common proteins between the two groups. Of these proteins, 76 were statistically different, of which 41 were characterized (P<.05). Pathway analysis demonstrated that in animals supplemented with resveratrol, there was a downregulation in several proteins involved with mitochondrial dysfunction, cell death, and unfavorable cardiac remodeling. Furthermore, there was an upregulation in proteins involved in free radical elimination. We conclude that resveratrol supplementation significantly alters several critical protein markers in the chronically ischemic myocardium. Further investigation of these proteins may help elucidate the mechanisms by which resveratrol exerts its cardioprotective effects. PMID:25089828

  5. A computational library for multiscale modeling of material failure

    NASA Astrophysics Data System (ADS)

    Talebi, Hossein; Silani, Mohammad; Bordas, Stéphane P. A.; Kerfriden, Pierre; Rabczuk, Timon

    2014-05-01

    We present an open-source software framework called PERMIX for multiscale modeling and simulation of fracture in solids. The framework is an object oriented open-source effort written primarily in Fortran 2003 standard with Fortran/C++ interfaces to a number of other libraries such as LAMMPS, ABAQUS, LS-DYNA and GMSH. Fracture on the continuum level is modeled by the extended finite element method (XFEM). Using several novel or state of the art methods, the piece software handles semi-concurrent multiscale methods as well as concurrent multiscale methods for fracture, coupling two continuum domains or atomistic domains to continuum domains, respectively. The efficiency of our open-source software is shown through several simulations including a 3D crack modeling in clay nanocomposites, a semi-concurrent FE-FE coupling, a 3D Arlequin multiscale example and an MD-XFEM coupling for dynamic crack propagation.

  6. Numerical Simulation of Damage using an Elastic-Viscoplastic Model with Directional Tensile Failure

    SciTech Connect

    Lomov, I

    2003-03-17

    A new continuum model for directional tensile failure has been developed that can simulate weakening and void formation due to directional tensile failure. The model is developed within the context of a properly invariant nonlinear thermomechanical theory. A second order damage tensor is introduced which allows simulation of weakening to tension applied in one direction, without weakening to subsequent tension applied in perpendicular directions. This damage tensor can be advected using standard methods in computer codes. Porosity is used as an isotropic measure of volumetric void strain and its evolution is influenced by tensile failure. The rate of dissipation due to directional tensile failure takes a particularly simple form, which can be analyzed easily. Specifically, the model can be combined with general constitutive equations for porous compaction and dilation, as well as viscoplasticity. A robust non-iterative numerical scheme for integrating these evolution equations is proposed. This constitutive model has been implemented into an Eulerian shock wave code with adaptive mesh refinement. A number of simulations of complicated shock loading of different materials have been performed including problems of fracture of rock. These simulations show that directionality of damage can play a significant role in material failure.

  7. Multiply charged neon clusters: failure of the liquid drop model?

    PubMed

    Mähr, I; Zappa, F; Denifl, S; Kubala, D; Echt, O; Märk, T D; Scheier, P

    2007-01-12

    We have analyzed the stability and fission dynamics of multiply charged neon cluster ions. The critical sizes for the observation of long-lived ions are n2=284 and n3=656 for charge states 2 and 3, respectively, a factor 3 to 4 below the predictions of a previously successful liquid-drop model. The preferred fragment ions of fission reactions are surprisingly small (2model. PMID:17358605

  8. The use of subjective expert opinions in cost optimum design of aerospace structures. [probabilistic failure models

    NASA Technical Reports Server (NTRS)

    Thomas, J. M.; Hanagud, S.

    1975-01-01

    The results of two questionnaires sent to engineering experts are statistically analyzed and compared with objective data from Saturn V design and testing. Engineers were asked how likely it was for structural failure to occur at load increments above and below analysts' stress limit predictions. They were requested to estimate the relative probabilities of different failure causes, and of failure at each load increment given a specific cause. Three mathematical models are constructed based on the experts' assessment of causes. The experts' overall assessment of prediction strength fits the Saturn V data better than the models do, but a model test option (T-3) based on the overall assessment gives more design change likelihood to overstrength structures than does an older standard test option. T-3 compares unfavorably with the standard option in a cost optimum structural design problem. The report reflects a need for subjective data when objective data are unavailable.

  9. 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.

  10. 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. PMID:25171521

  11. Failure prediction in automatically generated digital elevation models

    NASA Astrophysics Data System (ADS)

    Gooch, M. J.; Chandler, J. H.

    2001-10-01

    Developments in digital photogrammetry have provided the ability to generate digital elevation models (DEMs) automatically and are increasingly used by geoscientists. Using overlapping imagery, dense grids of digital elevations can be collected at high speeds (150 points per second) with a high level of accuracy. The trend towards using PC-based hardware, the widespread use of geographical information systems, and the forthcoming availability of high-resolution satellite imagery over the Internet at ever lower costs mean that the use of automated digital photogrammetry for elevation modelling is likely to become more widespread. Automation can reduce the need for an in-depth knowledge of the subject thus rendering the technology an option for more users. One criticism of the trend towards the automated "black box" approach is the lack of quality control procedures within the software, particularly with reference to identifying areas of the DEM with low accuracy. The traditional method of accuracy assessment is through the use of check point data (data collected by an independent method which has a higher level of accuracy against which the DEM can be compared). Check point data are, however, rarely available and it is typically recommended that the user manually check and edit the data using stereo viewing methods, a potentially lengthy process which can negate the obvious speed advantages brought about by automation. A data processing model has been developed that is capable of identifying areas where elevations are unreliable and to which the user should pay attention when editing and checking the data. The software model developed will be explained and described in detail in the paper. Results from tests on different scales of imagery, different types of imagery and other software packages will also be presented to demonstrate the efficacy and significantly the generality of the technique with other digital photogrammetric software systems.

  12. 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.

  13. 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.

  14. Dynamic tensile failure mechanics of the musculoskeletal neck using a cadaver model.

    PubMed

    Yliniemi, Eno M; Pellettiere, Joseph A; Doczy, Erica J; Nuckley, David J; Perry, Chris E; Ching, Randal P

    2009-05-01

    Although the catapult phase of pilot ejections has been well characterized in terms of human response to compressive forces, the effect of the forces on the human body during the ensuing ejection phases (including windblast and parachute opening shock) has not been thoroughly investigated. Both windblast and parachute opening shock have been shown to induce dynamic tensile forces in the human cervical spine. However, the human tolerance to such loading is not well known. Therefore, the main objective of this research project was to measure human tensile neck failure mechanics to provide data for computational modeling, anthropometric test device development, and improved tensile injury criteria. Twelve human cadaver specimens, including four females and eight males with a mean age of 50.1+/-9 years, were subjected to dynamic tensile loading through the musculoskeletal neck until failure occurred. Failure load, failure strain, and tensile stiffness were measured and correlated with injury type and location. The mean failure load for the 12 specimens was 3100+/-645 N, mean failure strain was 16.7+/-5.4%, and mean tensile stiffness was 172+/-54.5 N/mm. The majority of injuries (8) occurred in the upper cervical spine (Oc-C3), and none took place in the midcervical region (C3-C5). The results of this study assist in filling the existing void in dynamic tensile injury data and will aid in developing improved neck injury prevention strategies. PMID:19388771

  15. 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.

  16. 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

  17. 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

  18. Modeling human mortality using mixtures of bathtub shaped failure distributions.

    PubMed

    Bebbington, Mark; Lai, Chin-Diew; Zitikis, Ricardas

    2007-04-01

    Aging and mortality is usually modeled by the Gompertz-Makeham distribution, where the mortality rate accelerates with age in adult humans. The resulting parameters are interpreted as the frailty and decrease in vitality with age. This fits well to life data from 'westernized' societies, where the data are accurate, of high resolution, and show the effects of high quality post-natal care. We show, however, that when the data are of lower resolution, and contain considerable structure in the infant mortality, the fit can be poor. Moreover, the Gompertz-Makeham distribution is consistent with neither the force of natural selection, nor the recently identified 'late life mortality deceleration'. Although actuarial models such as the Heligman-Pollard distribution can, in theory, achieve an improved fit, the lack of a closed form for the survival function makes fitting extremely arduous, and the biological interpretation can be lacking. We show, that a mixture, assigning mortality to exogenous or endogenous causes, using the reduced additive and flexible Weibull distributions, models well human mortality over the entire life span. The components of the mixture are asymptotically consistent with the reliability and biological theories of aging. The relative simplicity of the mixture distribution makes feasible a technique where the curvature functions of the corresponding survival and hazard rate functions are used to identify the beginning and the end of various life phases, such as infant mortality, the end of the force of natural selection, and late life mortality deceleration. We illustrate our results with a comparative analysis of Canadian and Indonesian mortality data. PMID:17188716

  19. Failure analysis and modeling of a multicomputer system. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Subramani, Sujatha Srinivasan

    1990-01-01

    This thesis describes the results of an extensive measurement-based analysis of real error data collected from a 7-machine DEC VaxCluster multicomputer system. In addition to evaluating basic system error and failure characteristics, we develop reward models to analyze the impact of failures and errors on the system. The results show that, although 98 percent of errors in the shared resources recover, they result in 48 percent of all system failures. The analysis of rewards shows that the expected reward rate for the VaxCluster decreases to 0.5 in 100 days for a 3 out of 7 model, which is well over a 100 times that for a 7-out-of-7 model. A comparison of the reward rates for a range of k-out-of-n models indicates that the maximum increase in reward rate (0.25) occurs in going from the 6-out-of-7 model to the 5-out-of-7 model. The analysis also shows that software errors have the lowest reward (0.2 vs. 0.91 for network errors). The large loss in reward rate for software errors is due to the fact that a large proportion (94 percent) of software errors lead to failure. In comparison, the high reward rate for network errors is due to fast recovery from a majority of these errors (median recovery duration is 0 seconds).

  20. 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

  1. 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

  2. In a Swine Model, Chest Compressions Cause Ventricular Capture, and By Means of a Long-Short Sequence, Ventricular Fibrillation

    PubMed Central

    Osorio, Jose; Dosdall, Derek J; Robichaux, Robert P; Tabereaux, Paul B.; Ideker, Raymond E

    2009-01-01

    Background During resuscitation, fibrillation often recurs. In swine, we studied refibrillation after long duration ventricular fibrillation (LDVF) investigating an association with chest compressions (CCs). Methods and Results In Protocol A, 47 episodes of LDVF lasting at least 2.5 min were induced in 8 animals. Following defibrillation, CCs were required for 35 episodes and delivered with a pneumatic device (Lucas-CPR). In 9 episodes, refibrillation occurred within 2 s of CC initiation (Group 1) and in 26 episodes CCs were delivered without refibrillation (Group 2). From the ECG and intracardiac electrodes, the RR interval preceding CCs, the shortest cycle length during the first 2 CCs (Short) and the preceding cycle length (Long) were measured. A similar study was conducted in 3 more animals without intracardiac catheters (Protocol B). In Protocol A, the mean RR before CC was 665±292ms in Group 1 and 769±316 in Group 2. CCs stimulated ventricular beats in all 35 episodes. The Short and Long intervals were shorter in Group 1 (215±31ms and 552±210ms), than in Group 2 (402±153ms and 699±147ms) (p=0.009 and p=0.04, respectively). The Prematurity Index (Short/RR) was lower in Group 1 (0.35±0.09) than Group 2 (0.58±0.21) (p<0.01). A Short interval < 231 ms predicted refibrillation with 88% sensitivity and 91% specificity. In Protocol B, CCs were required in 11 episodes, causing ventricular stimulation in all of them and VF within the first 2 CCs in 3. Conclusions Under some conditions, CC during resuscitation can stimulate the ventricles and initiate VF by a long-short sequence. PMID:19808420

  3. 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.

  4. Describing antimicrobial use and reported treatment efficacy in Ontario swine using the Ontario swine veterinary-based Surveillance program

    PubMed Central

    2013-01-01

    Background The objective of this work was to retrospectively assess records received through the Ontario Swine Veterinary-based Surveillance program July 2007 – July 2009 to describe and assess relationships between reported treatment failure, antimicrobial use, diagnosis and body system affected. Results Antimicrobial use occurred in 676 records, 80.4% of all records recording treatment (840). The most commonly used antimicrobials were penicillin (34.9%), tetracyclines (10.7%) and ceftiofur (7.8%), and the use of multiple antimicrobials occurred in 141/676 records (20.9%). A multi-level logistic regression model was built to describe the probability of reported treatment failure. The odds of reported treatment failure were significantly reduced if the record indicated that the gastro-intestinal (GI) system was affected, as compared to all other body systems (p < 0.05). In contrast, the odds of reported treatment failure increased by 1.98 times if two antimicrobials were used as compared to one antimicrobial (p = 0.009) and by 6.52 times if three or more antimicrobials were used as compared to one antimicrobial (p = 0.005). No significant increase in reported treatment failure was seen between the use of two antimicrobials and three or more antimicrobials. No other antimicrobials were significantly associated with reported treatment failure after controlling for body system and the number of antimicrobials used. Conclusions Failure of antimicrobial treatment is more likely to occur in non-GI conditions, as compared to GI conditions and the use of multiple antimicrobial products is also associated with an increased probability of antimicrobial treatment failure. The authors suggest that a more preventative approach to herd health should be taken in order to reduce antimicrobial inputs on-farm, including improved immunity via vaccination, management and biosecurity strategies. Furthermore, improved immunity may be viewed as a form of antimicrobial

  5. 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

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Interstate movement of swine semen and swine embryos for insemination of or implantation into swine. 85.10 Section 85.10 Animals and Animal... ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS PSEUDORABIES § 85.10 Interstate movement of swine...

  6. 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

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Interstate movement of swine semen and swine embryos for insemination of or implantation into swine. 85.10 Section 85.10 Animals and Animal... ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS PSEUDORABIES § 85.10 Interstate movement of swine...

  7. 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

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Interstate movement of swine semen and swine embryos for insemination of or implantation into swine. 85.10 Section 85.10 Animals and Animal... ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS PSEUDORABIES § 85.10 Interstate movement of swine...

  8. 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

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Interstate movement of swine semen and swine embryos for insemination of or implantation into swine. 85.10 Section 85.10 Animals and Animal... ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS PSEUDORABIES § 85.10 Interstate movement of swine...

  9. 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

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Interstate movement of swine semen and swine embryos for insemination of or implantation into swine. 85.10 Section 85.10 Animals and Animal... ANIMALS (INCLUDING POULTRY) AND ANIMAL PRODUCTS PSEUDORABIES § 85.10 Interstate movement of swine...

  10. 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

  11. 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

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. Vegetative buffers for swine odor mitigation - wind tunnel evaluation of air flow dynamics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Scale model wind tunnel experiments were completed to determine the effectiveness and feasibility of vegetative buffers to mitigate swine odor and particulate transport. Three series of wind tunnel experiments were completed. The first included four swine housing unit models and either a slurry tank...

  17. 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. PMID:27263180

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. A compressive failure model for anisotropic plates with a cutout under compressive and shear loads

    NASA Technical Reports Server (NTRS)

    Gurdal, Z.; Haftka, R. T.

    1986-01-01

    The paper introduces a failure model for laminated composite plates with a cutout under combined compressive and shear loads. The model is based on kinking failure of the load-carrying fibers around a cutout, and includes the effect of local shearing and compressive stresses. Comparison of predictions of the model with available experimental results for quasi-isotropic and orthotropic plates with a circular hole indicated a good agreement. Predictions for orthotropic plates under combined loading are compared with the predictions of a point-stress model. The present model indicates significant reductions in axial load-carrying capacity due to shearing loads for plates with principal axis of orthotropy oriented along the axial load direction. A gain in strength is achieved by rotating the axis of orthotropy to counteract the shearing stress, or by eliminating the compressive-shear deformation coupling.

  4. Model-based failure detection for cylindrical shells from noisy vibration measurements.

    PubMed

    Candy, J V; Fisher, K A; Guidry, B L; Chambers, D H

    2014-12-01

    Model-based processing is a theoretically sound methodology to address difficult objectives in complex physical problems involving multi-channel sensor measurement systems. It involves the incorporation of analytical models of both physical phenomenology (complex vibrating structures, noisy operating environment, etc.) and the measurement processes (sensor networks and including noise) into the processor to extract the desired information. In this paper, a model-based methodology is developed to accomplish the task of online failure monitoring of a vibrating cylindrical shell externally excited by controlled excitations. A model-based processor is formulated to monitor system performance and detect potential failure conditions. The objective of this paper is to develop a real-time, model-based monitoring scheme for online diagnostics in a representative structural vibrational system based on controlled experimental data. PMID:25480059

  5. 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.

  6. 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. PMID:25469817

  7. Self-Conscious Emotions in Response to Perceived Failure: A Structural Equation Model

    ERIC Educational Resources Information Center

    Bidjerano, Temi

    2010-01-01

    This study explored the occurrence of self-conscious emotions in response to perceived academic failure among 4th-grade students from the United States and Bulgaria, and the author investigated potential contributors to such negative emotional experiences. Results from structural equation modeling indicated that regardless of country, negative…

  8. Developing a Model for Identifying Students at Risk of Failure in a First Year Accounting Unit

    ERIC Educational Resources Information Center

    Smith, Malcolm; Therry, Len; Whale, Jacqui

    2012-01-01

    This paper reports on the process involved in attempting to build a predictive model capable of identifying students at risk of failure in a first year accounting unit in an Australian university. Identifying attributes that contribute to students being at risk can lead to the development of appropriate intervention strategies and support…

  9. 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.

  10. Children at Risk for Academic Failure: A Model of Individual and Family Factors

    ERIC Educational Resources Information Center

    Quilliams, Laura; Beran, Tanya

    2009-01-01

    The purpose of this study was to identify individual and family risk factors that may explain why some students are at risk for academic failure. Students' self-concept, academic motivation, and their parents' involvement in education were reported by both students and teachers. A latent variable path model fit the data well (Comparative Fit Index…

  11. Early Treatment Outcome in Failure to Thrive: Predictions from a Transactional Model.

    ERIC Educational Resources Information Center

    Drotar, Dennis

    Children diagnosed with environmentally based failure to thrive early during their first year of life were seen at 12 and 18 months for assessment of psychological development (cognition, language, symbolic play, and behavior during testing). Based on a transactional model of outcome, factors reflecting biological vulnerability (wasting and…

  12. Swine influenza virus: epidemiology and vaccine concerns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction. Swine influenza virus (SIV) is a primary cause of respiratory disease in swine and a component of the porcine respiratory disease complex (PRDC). Influenza viruses are an important health and economic concern for swine producers throughout the world. Swine operations may be affected by...

  13. 9 CFR 91.9 - Swine.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Swine. 91.9 Section 91.9 Animals and... EXPORTATION Diagnostic Tests, Treatments § 91.9 Swine. (a) No swine shall be exported if they were fed garbage at any time. The swine shall be accompanied by a certification from the owner stating that they...

  14. 9 CFR 91.9 - Swine.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Swine. 91.9 Section 91.9 Animals and... EXPORTATION Diagnostic Tests, Treatments § 91.9 Swine. (a) No swine shall be exported if they were fed garbage at any time. The swine shall be accompanied by a certification from the owner stating that they...

  15. 9 CFR 91.9 - Swine.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Swine. 91.9 Section 91.9 Animals and... EXPORTATION Diagnostic Tests, Treatments § 91.9 Swine. (a) No swine shall be exported if they were fed garbage at any time. The swine shall be accompanied by a certification from the owner stating that they...

  16. 9 CFR 91.9 - Swine.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Swine. 91.9 Section 91.9 Animals and... EXPORTATION Diagnostic Tests, Treatments § 91.9 Swine. (a) No swine shall be exported if they were fed garbage at any time. The swine shall be accompanied by a certification from the owner stating that they...

  17. 9 CFR 91.9 - Swine.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Swine. 91.9 Section 91.9 Animals and... EXPORTATION Diagnostic Tests, Treatments § 91.9 Swine. (a) No swine shall be exported if they were fed garbage at any time. The swine shall be accompanied by a certification from the owner stating that they...

  18. Field-scale and wellbore modeling of compaction-induced casing failures

    SciTech Connect

    Hilbert, L.B. Jr.; Gwinn, R.L.; Moroney, T.A.; Deitrick, G.L.

    1999-06-01

    Presented in this paper are the results and verification of field- and wellbore-scale large deformation, elasto-plastic, geomechanical finite element models of reservoir compaction and associated casing damage. The models were developed as part of a multidisciplinary team project to reduce the number of costly well failures in the diatomite reservoir of the South Belridge Field near Bakersfield, California. Reservoir compaction of high porosity diatomite rock induces localized shearing deformations on horizontal weak-rock layers and geologic unconformities. The localized shearing deformations result in casing damage or failure. Two-dimensional, field-scale finite element models were used to develop relationships between field operations, surface subsidence, and shear-induced casing damage. Pore pressures were computed for eighteen years of simulated production and water injection, using a three-dimensional reservoir simulator. The pore pressures were input to the two-dimensional geomechanical field-scale model. Frictional contact surfaces were used to model localized shear deformations. To capture the complex casing-cement-rock interaction that governs casing damage and failure, three-dimensional models of a wellbore were constructed, including a frictional sliding surface to model localized shear deformation. Calculations were compared to field data for verification of the models.

  19. Blood-Banking Techniques for Plateletpheresis in Swine

    PubMed Central

    Sondeen, Jill L; Prince, Malcolm D; Polykratis, Irene A; Hernandez, Orlando; Torres-Mendoza, Jaime; Guzman, Rodolfo De; Aden, James K; Dubick, Michael A

    2014-01-01

    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 prehospital 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. PMID:24827574

  20. 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

  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. A model of chronic heart failure in spontaneous hypertensive rats (SHR).

    PubMed

    Itter, G; Jung, W; Juretschke, P; Schoelkens, B A; Linz, W

    2004-04-01

    Common models of chronic heart failure (CHF) do not always result in parameters and symptoms that can be extrapolated to the clinical situation of patients with end-stage heart failure. The aim of this study was to establish and validate a new model of CHF in the rat. CHF was induced in Wistar Kyoto (WKY/NHsd) and spontaneously hypertensive (SHR/NHsd) rats by creating a permanent (8-week) occlusion of the left coronary artery 2 mm distal to the origin from the aorta by a modified technique. This resulted in a large infarction of the free left ventricular wall. The focus of attention was the validation of the geometric properties of the left ventricle and its contractility. The validation of the geometric properties of the left ventricle was done by a non-invasive magnetic resonance imaging (MRI) technique and by planimetry (stereology). Cardiodynamics (e.g. contractility) were evaluated in the isolated 'working heart' model. We were able to establish a new and predictive model of heart failure in the spontaneously hypertensive rat 8 weeks after coronary artery ligation. At this time point, the WKY rat did not show any symptoms of CHF. The model represents characteristic parameters and symptoms that can be extrapolated to the clinical situation of patients with end-stage heart failure (NYHA III-IV). Upon inspection, severe clinical symptoms of congestive heart failure were prominent, such as dyspnoea, subcutaneous oedema, pale-bluish limbs and impaired motion. Non-invasive sequential measurements by NMR techniques showed lung oedema, hydrothorax, large dilated left and right ventricular chambers and hypertrophy of the septum. The infarcted animals showed a reduced heart power, diminished contractility and enhanced heart work, much more so in the SHR/NHsd rat than in the WKY/NHsd rat. Furthermore the infarcted animals showed enhanced levels of hydroxyproline/proline ratios, again much more so in the SHR/NHsd rat than in the WKY/NHsd rat. PMID:15070453

  3. 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.

  4. 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.

  5. Accurate analytical modelling of cosmic ray induced failure rates of power semiconductor devices

    NASA Astrophysics Data System (ADS)

    Bauer, Friedhelm D.

    2009-06-01

    A new, simple and efficient approach is presented to conduct estimations of the cosmic ray induced failure rate for high voltage silicon power devices early in the design phase. This allows combining common design issues such as device losses and safe operating area with the constraints imposed by the reliability to result in a better and overall more efficient design methodology. Starting from an experimental and theoretical background brought forth a few yeas ago [Kabza H et al. Cosmic radiation as a cause for power device failure and possible countermeasures. In: Proceedings of the sixth international symposium on power semiconductor devices and IC's, Davos, Switzerland; 1994. p. 9-12, Zeller HR. Cosmic ray induced breakdown in high voltage semiconductor devices, microscopic model and possible countermeasures. In: Proceedings of the sixth international symposium on power semiconductor devices and IC's, Davos, Switzerland; 1994. p. 339-40, and Matsuda H et al. Analysis of GTO failure mode during d.c. blocking. In: Proceedings of the sixth international symposium on power semiconductor devices and IC's, Davos, Switzerland; 1994. p. 221-5], an exact solution of the failure rate integral is derived and presented in a form which lends itself to be combined with the results available from commercial semiconductor simulation tools. Hence, failure rate integrals can be obtained with relative ease for realistic two- and even three-dimensional semiconductor geometries. Two case studies relating to IGBT cell design and planar junction termination layout demonstrate the purpose of the method.

  6. 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.

  7. Probabilistic model of waiting times between large failures in sheared media

    NASA Astrophysics Data System (ADS)

    Brinkman, Braden A. W.; LeBlanc, Michael P.; Uhl, Jonathan T.; Ben-Zion, Yehuda; Dahmen, Karin A.

    2016-01-01

    Using a probabilistic approximation of a mean-field mechanistic model of sheared systems, we analytically calculate the statistical properties of large failures under slow shear loading. For general shear F (t ) , the distribution of waiting times between large system-spanning failures is a generalized exponential distribution, ρT(t ) =λ ( F (t ) ) P ( F (t ) ) exp[-∫0td τ λ ( F (τ ) ) P ( F (τ ) ) ] , where λ ( F (t )) is the rate of small event occurrences at stress F (t ) and P ( F (t )) is the probability that a small event triggers a large failure. We study the behavior of this distribution as a function of fault properties, such as heterogeneity or shear rate. Because the probabilistic model accommodates any stress loading F (t ) , it is particularly useful for modeling experiments designed to understand how different forms of shear loading or stress perturbations impact the waiting-time statistics of large failures. As examples, we study how periodic perturbations or fluctuations on top of a linear shear stress increase impact the waiting-time distribution.

  8. 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.

  9. λ -prophage induction modeled as a cooperative failure mode of lytic repression

    NASA Astrophysics Data System (ADS)

    Chia, Nicholas; Golding, Ido; Goldenfeld, Nigel

    2009-09-01

    We analyze a system-level model for lytic repression of λ phage in E. coli using reliability theory, showing that the repressor circuit comprises four redundant components whose failure mode is prophage induction. Our model reflects the specific biochemical mechanisms involved in regulation, including long-range cooperative binding, and its detailed predictions for prophage induction in E. coli under ultraviolet radiation are in good agreement with experimental data.

  10. λ-prophage induction modeled as a cooperative failure mode of lytic repression

    NASA Astrophysics Data System (ADS)

    Chia, Nicholas; Golding, Ido; Goldenfeld, Nigel

    2009-03-01

    We analyze a system-level model for lytic repression of λ-phage in E. coli/ using reliability theory, showing that the repressor circuit comprises 4 redundant components whose failure mode is prophage induction. Our model reflects the specific biochemical mechanisms involved in regulation, including long-range cooperative binding, and its detailed predictions for prophage induction in E. coli/ under ultra-violet radiation are in good agreement with experimental data.

  11. Swine Dialyzable Spleen Extract as Antiviral Prophylaxis.

    PubMed

    Merchand-Reyes, Giovanna; Pavón, Lenin; Pérez-Sánchez, Gilberto; Vázquez-Leyva, Said; Salinas-Jazmín, Nohemí; Velasco-Velázquez, Marco; Medina-Rivero, Emilio; Pérez-Tapia, Sonia Mayra

    2015-11-01

    Worldwide, the most highly consumed meat is of porcine origin. The production and distribution of swine meat are affected by diverse health matters, such as influenza and diarrhea, which cause head losses and require the use of antibiotics and other drugs in hog farms. To stimulate newborn piglet immune responses and increase resistance to infections, we developed a spray-drying technique to produce dried swine dialyzable spleen extract (sDSE), an immunomodulator. Based on the size-exclusion ultra performance liquid chromatography quantitative analysis, it was possible to recover up to 58% of the product after the drying process. The biological activity of orally administered dried sDSE increased mouse survival and induced cytokine production in a herpes infection model. PMID:25867497

  12. Proportional-hazards models for improving the analysis of light-water-reactor-component failure data

    SciTech Connect

    Booker, J.B.; Johnson, M.E.; Easterling, R.G.

    1981-01-01

    The reliability of a power plant component may depend on a variety of factors (or covariates). If a single regression model can be specified to relate these factors to the failure rate, then all available data can be used to estimate and test for the effects of these covariates. One such model is a proportional hazards function that is specified as a product of two terms: a nominal hazard rate that is a function of time and a second term that is a function of the covariates. The purpose of this paper is to adapt two such models to LWR valve failure rate analysis, to compare the results, and to discuss the strengths and weaknesses of these applications.

  13. Congestive heart failure model in rabbits: effects of digoxin and a drug containing toad venom.

    PubMed

    Morishita, S; Shoji, M; Oguni, Y; Ito, C; Noguchi, K; Sakanashi, M

    1991-08-01

    A low-output-type heart failure model was established in rabbits by protease treatment of the surface of the left ventricular anterior wall. Heart rate, aortic blood flow (AoF), left ventricular pressure (LVP) and maximal rate of rise of LVP (max dP/dt) in this model were maintained at lower levels than in normal rabbits, while left ventricular end-diastolic pressure (LVEDP) and systemic vascular resistance (SVR) were maintained at higher levels, and mean blood pressure (MBP) remained at a normal level. Intraduodenal administration of digoxin and a drug containing toad venom (Kyushin:KY) improved the hemodynamic parameters by increasing the AoF, LVP and max dP/dt and by decreasing the LVEDP and SVR without a significant change in MBP. These results suggest that the beneficial effects of digoxin and KY on this heart failure model originate from their cardiotonic activity. PMID:1744986

  14. 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.

  15. Left anterior descending coronary artery blood flow and left ventricular unloading during extracorporeal membrane oxygenation support in a swine model of acute cardiogenic shock.

    PubMed

    Brehm, Christoph; Schubert, Sarah; Carney, Elizabeth; Ghodsizad, Ali; Koerner, Michael; McCoach, Robert; El-Banayosy, Aly

    2015-02-01

    The impact of extracorporeal membrane oxygenation (ECMO) support on coronary blood flow and left ventricular unloading is still debated. This study aimed to further characterize the influence of ECMO on coronary artery blood flow and its ability to unload the left ventricle in a short-term model of acute cardiogenic shock. Seven anesthetized pigs were intubated and then underwent median sternotomy and cannulation for venoarterial (VA) ECMO. Flow in the left anterior descending (LAD) artery, left atrial pressure (LAP), left ventricular end-diastolic pressure (LVEDP), and mean arterial pressure (MAP) were measured before and after esmolol-induced cardiac dysfunction and after initiating VA-ECMO support. Induction of acute cardiogenic shock was associated with short-term increases in LAP from 8 ± 4 mm Hg to 18 ± 14 mm Hg (P = 0.9) and LVEDP from 5 ± 2 mm Hg to 13 ± 17 mm Hg (P = 0.9), and a decrease in MAP from 63 ± 16 mm Hg to 50 ± 24 mm Hg (P = 0.3). With VA-ECMO support, blood flow in the LAD increased from 28 ± 25 mL/min during acute unsupported cardiogenic shock to 67 ± 50 mL/min (P = 0.003), and LAP and LVEDP decreased to 8 + 5 mm Hg (P = 0.7) and 5 ± 3 mm Hg (P = 0.5), respectively. In this swine model of acute cardiogenic shock, VA-ECMO improved coronary blood flow and provided some degree of left ventricular unloading for the short duration of the study. PMID:24935151

  16. New Insights on the Management of Wildlife Diseases Using Multi-State Recapture Models: The Case of Classical Swine Fever in Wild Boar

    PubMed Central

    Rossi, Sophie; Toigo, Carole; Hars, Jean; Pol, Françoise; Hamann, Jean-Luc; Depner, Klaus; Le Potier, Marie-Frederique

    2011-01-01

    Background The understanding of host-parasite systems in wildlife is of increasing interest in relation to the risk of emerging diseases in livestock and humans. In this respect, many efforts have been dedicated to controlling classical swine fever (CSF) in the European Wild Boar. But CSF eradication has not always been achieved even though vaccination has been implemented at a large-scale. Piglets have been assumed to be the main cause of CSF persistence in the wild since they appeared to be more often infected and less often immune than older animals. However, this assumption emerged from laboratory trials or cross-sectional surveys based on the hunting bags. Methodology/Principal Findings In the present paper we conducted a capture-mark-recapture study in free-ranging wild boar piglets that experienced both CSF infection and vaccination under natural conditions. We used multi-state capture recapture models to estimate the immunization and infection rates, and their variations according to the periods with or without vaccination. According to the model prediction, 80% of the infected piglets did not survive more than two weeks, while the other 20% quickly recovered. The probability of becoming immune did not increase significantly during the summer vaccination sessions, and the proportion of immune piglets was not higher after the autumn vaccination. Conclusions/Significance Given the high lethality of CSF in piglets highlighted in our study, we consider unlikely that piglets could maintain the chain of CSF virus transmission. Our study also revealed the low efficacy of vaccination in piglets in summer and autumn, possibly due to the low palatability of baits to that age class, but also to the competition between baits and alternative food sources. Based on this new information, we discuss the prospects for the improvement of CSF control and the interest of the capture-recapture approach for improving the understanding of wildlife diseases. PMID:21977225

  17. UPTAKE OF DIOXIN-LIKE COMPOUNDS IN GROWING SWINE: CORRELATION BETWEEN EXPERIMENTAL AND PREDICTED DATA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Experimental data on the accumulation of dioxins from feed into the back fat of swine were compared to calculated data from a mathematical model developed to predict the concentration of dioxin-like compounds in growing swine. The experimental data were acquired in a feeding study in which 14 gilts...

  18. Shiga toxin-producing Escherichia coli in swine: the public health perspective

    PubMed Central

    Tseng, Marion; Fratamico, Pina M.; Manning, Shannon D.; Funk, Julie A.

    2014-01-01

    Shiga toxin-producing Escherichia coli (STEC) strains are food-borne pathogens that are an important public health concern. STEC infection is associated with severe clinical diseases in human beings, including hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS), which can lead to kidney failure and death. Cattle are the most important STEC reservoir. However, a number of STEC outbreaks and HUS cases have been attributed to pork products. In swine, STEC strains are known to be associated with edema disease. Nevertheless, the relationship between STEC of swine origin and human illness has yet to be determined. This review critically summarizes epidemiologic and biological studies of swine STEC. Several epidemiologic studies conducted in multiple regions of the world have demonstrated that domestic swine can carry and shed STEC. Moreover, animal studies have demonstrated that swine are susceptible to STEC O157:H7 infection and can shed the bacterium for 2 months. A limited number of molecular epidemiologic studies, however, have provided conflicting evidence regarding the relationship between swine STEC and human illness. The role that swine play in STEC transmission to people and the contribution to human disease frequency requires further evaluation. PMID:24397985

  19. Structural analysis of Turtle Mountain (Alberta) using digital elevation model: Toward a progressive failure

    NASA Astrophysics Data System (ADS)

    Jaboyedoff, Michel; Couture, Réjean; Locat, Pascal

    2009-01-01

    In 1903, the eastern slope of Turtle Mountain (Alberta) was affected by a 30 M m 3-rockslide named Frank Slide that resulted in more than 70 casualties. Assuming that the main discontinuity sets, including bedding, control part of the slope morphology, the structural features of Turtle Mountain were investigated using a digital elevation model (DEM). Using new landscape analysis techniques, we have identified three main joint and fault sets. These results are in agreement with those sets identified through field observations. Landscape analysis techniques, using a DEM, confirm and refine the most recent geology model of the Frank Slide. The rockslide was initiated along bedding and a fault at the base of the slope and propagated up slope by a regressive process following a surface composed of pre-existing discontinuities. The DEM analysis also permits the identification of important geological structures along the 1903 slide scar. Based on the so called Sloping Local Base Level (SLBL) an estimation was made of the present unstable volumes in the main scar delimited by the cracks, and around the south area of the scar (South Peak). The SLBL is a method permitting a geometric interpretation of the failure surface based on a DEM. Finally we propose a failure mechanism permitting the progressive failure of the rock mass that considers gentle dipping wedges (30°). The prisms or wedges defined by two discontinuity sets permit the creation of a failure surface by progressive failure. Such structures are more commonly observed in recent rockslides. This method is efficient and is recommended as a preliminary analysis prior to field investigation.

  20. Consumption of beef from cattle administered estrogenic growth promotants does not result in premature puberty and obesity using the swine model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective was to investigate the effects of ground beef from cattle administered commercial growth promotants on puberty attainment and body composition in female swine. Twenty-four gilts were selected based on strict selection criteria to reduce piglet variation. Treatments were randomly assign...

  1. 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...

  2. Genetic determinants of cutaneous malignant melanoma in Sinclair swine.

    PubMed

    Blangero, J; Tissot, R G; Beattie, C W; Amoss, M S

    1996-03-01

    The role of genetic factors involved in the determination of risk of cutaneous malignant melanoma (CMM) in humans remains unclear owing to genetic heterogeneity and reliance on simplistic models of inheritance. Here, we report a statistical genetic analysis of cutaneous malignant melanoma in Sinclair swine (SSCM), a unique animal model for human CMM. Using complex segregation analysis a two-locus model involving an unknown major locus and a second locus that lies within or close to the swine leukocyte antigen (SLA) complex jointly determine risk of SSCM in pedigreed animals. These loci also influence severity of affection, accounting for approximately 20% of the phenotypic variation in quantitative tumour burden. PMID:8605105

  3. Odorous VOC emission following land application of swine manure slurry

    NASA Astrophysics Data System (ADS)

    Parker, David B.; Gilley, John; Woodbury, Bryan; Kim, Ki-Hyun; Galvin, Geordie; Bartelt-Hunt, Shannon L.; Li, Xu; Snow, Daniel D.

    2013-02-01

    Swine manure is often applied to crop land as a fertilizer source. Odor emissions from land-applied swine manure may pose a nuisance to downwind populations if manure is not applied with sufficient forethought. A research project was conducted to assess the time decay of odorous volatile organic compound (VOC) emissions following land application of swine manure. Three land application methods were compared: surface application, incorporation 24 h after surface application, and injection. Emission rates were measured in field plots using a small wind tunnel and sorbent tubes. VOCs including eight volatile fatty acids, five aromatics, and two sulfur-containing compounds were quantified by gas chromatography-mass spectrometry. In most cases, a first order exponential decay model adequately described the flux versus time relationship for the 24 h period following land application, but the model sometimes overestimated flux in the 6-24 h range. The same model but with the time term squared adequately predicted flux over the entire 24 h period. Three compounds (4-methylphenol, skatole, and 4-ethylphenol) accounted for 93 percent of the summed odor activity value. First order decay constants (k) for these three compounds ranged from 0.157 to 0.996 h-1. When compared to surface application, injection of swine manure resulted in 80-95 percent lower flux for the most odorous aromatic compounds. These results show that VOC flux decreases rapidly following land application of swine manure, declining below levels of detection and near background levels after 4 to 8 h.

  4. 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

  5. Implications of bank failures and fluvial erosion for gully development: Field observations and modeling

    NASA Astrophysics Data System (ADS)

    Istanbulluoglu, Erkan; Bras, Rafael L.; Flores-Cervantes, Homero; Tucker, Gregory E.

    2005-03-01

    Gully erosion is most commonly triggered by fluvial erosion following natural and anthropogenic disturbances or as a response to changes in climate and tectonic forcing and base level drop. Field observations attribute the headward growth and widening of many gully systems to gravitational mass-wasting processes of oversteepened sidewalls. Soil saturation, groundwater sapping, and tension crack development contribute to the instability. Recent landscape evolution models treat such mass failures as slope-dependent continuous sediment transport processes, sometimes conditioned on a slope threshold or with nonlinear dependence on slope gradient. In this study we first present an explicit physically based theory for the stability analysis of gully heads and walls. The theory is based on the force balance equation of an assumed planar failure geometry of a steep gully wall, with a potential failure plane dipping into the incised gully bed and tension cracks developing behind the scarp face. Then, we test the theory against field data collected in our field site in Colorado and against other published data. Second, the theory is implemented in a one-dimensional hillslope profile development model and the three-dimensional channel-hillslope integrated landscape development (CHILD) to study the effects of soil cohesion, erosion thresholds, and stochastic climate on the tempo of gully development and morphology. Preliminary results indicate that wider and shallower gullies develop and integrate, forming wide valleys, when soil cohesion is small. As soil cohesion increases, erosion slows down, gullies become deeper with vertical walls, and episodic mass failures occur. Differences in storm intensity-duration characteristics and erosion thresholds are predicted to have a significant impact on gully development. Vertical gully walls develop rapidly, and gullies enlarge by slab failures in a climate characterized by high-intensity, short-duration storm pulses. However, under

  6. Sizing up models of heart failure: Proteomics from flies to humans

    PubMed Central

    Kooij, Viola; Venkatraman, Vidya; Tra, John; Kirk, Jonathan A; Rowell, Janelle; Blice-Baum, Anna; Cammarato, Anthony; Van Eyk, Jennifer E

    2014-01-01

    Cardiovascular disease is the leading cause of death in the western world. Heart failure is a heterogeneous and complex syndrome, arising from various etiologies, which result in cellular phenotypes that vary from patient to patient. The ability to utilize genetic manipulation and biochemical experimentation in animal models has made them indispensable in the study of this chronic condition. Similarly, proteomics has been helpful for elucidating complicated cellular and molecular phenotypes and has the potential to identify circulating biomarkers and drug targets for therapeutic intervention. In this review, the use of human samples and animal model systems (pig, dog, rat, mouse, zebrafish, and fruit fly) in cardiac research is discussed. Additionally, the protein sequence homology between these species and the extent of conservation at the level of the phospho-proteome in major kinase signaling cascades involved in heart failure are investigated. PMID:24723306

  7. 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.

  8. 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.

  9. 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.

  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. 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.

  12. Modeling the implications of fluvial erosion and bank failures on gully development and growth

    NASA Astrophysics Data System (ADS)

    Istanbulluoglu, E.; Flores, H.; Bras, R.; Tucker, G.

    2003-12-01

    Exploring landscape development due to gully erosion has been an important component in Michael J. Kirkby's scientific career. Gully erosion is most commonly triggered by fluvial erosion due to natural and anthropogenic disturbances, or as a response to changes in climate and tectonic forcing, and base level drop. Field observations suggest that following the development of fluvial incisions, headward growth and widening of many gully systems can be attributed to the instability and collapse of steepened gully walls. Soil saturation, sapping and development of tension cracks contribute to the instability. Recent landscape evolution models treat such mass failures as slope dependent continuous sediment transport processes, sometimes conditioned on a slope threshold or with nonlinear dependence on slope gradient. In this study, first we present a theory for stability analysis of gully head and walls. The theory is based on force balance equation of an assumed planar failure geometry of a steep gully wall, with a potential failure plane dipping to the incised gully bed. We consider development of vertical tension cracks behind the face of the gully head that extend down to the failure plane. In the theory, storm water infiltrates in the tension cracks and generates hydrostatic forces in the vertical crack face, and uplift forces along the failure plane. During storms, water level in the crack is related to steady-state basin hydrology. In our model when tension cracks are either dry or completely filled with runoff water, instability occurs when headcut height exceeds a critical threshold (higher for the dry case). For the case when cracks are partially filled, our theory predicts an inverse relationship between headcut height and drainage area. We used field observations in Colorado and another published data set to test our model. Second, we have implemented this theory in the CHILD landscape evolution model and explored the effects of soil cohesion, erosion

  13. 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.

  14. A Weibull brittle material failure model for the ABAQUS computer program

    SciTech Connect

    Bennett, J.

    1991-08-01

    A statistical failure theory for brittle materials that traces its origins to the Weibull distribution function is developed for use in the general purpose ABAQUS finite element computer program. One of the fundamental assumptions for this development is that Mode 1 microfractures perpendicular to the direction of the principal stress contribute independently to the fast fracture. The theory is implemented by a user subroutine for ABAQUS. Example problems illustrating the capability and accuracy of the model are given. 24 refs., 12 figs.

  15. An accelerated failure time model for investigating pedestrian crossing behavior and waiting times at signalized intersections.

    PubMed

    Yang, Xiaobao; Abdel-Aty, Mohamed; Huan, Mei; Peng, Yichuan; Gao, Ziyou

    2015-09-01

    The waiting process is crucial to pedestrians in the street-crossing behavior. Once pedestrians terminate their waiting behavior during the red light period, they would cross against the red light and put themselves in danger. A joint hazard-based duration model is developed to investigate the effect of various covariates on pedestrian crossing behavior and to estimate pedestrian waiting times at signalized intersections. A total of 1181 pedestrians approaching the intersections during red light periods were observed in Beijing, China. Pedestrian crossing behaviors are classified into immediate crossing behavior and waiting behavior. The probability and effect of various covariates for pedestrians' immediate crossing behavior are identified by a logit model. Four accelerated failure time duration models based on the exponential, Weibull, lognormal and log-logistic distributions are proposed to examine the significant risk factors affecting duration times for pedestrians' waiting behavior. A joint duration model is developed to estimate pedestrian waiting times. Moreover, unobserved heterogeneity is considered in the proposed model. The results indicate that the Weibull AFT model with shared frailty is appropriate for modelling pedestrian waiting durations. Failure to account for heterogeneity would significantly underestimate the effects of covariates on waiting duration times. The proposed model provides a better understanding of pedestrian crossing behavior and more accurate estimation of pedestrian waiting times. It may be applicable in traffic system analysis in developing countries with high flow of mixed traffic. PMID:26072184

  16. Accelerated ovarian failure: a novel, chemically induced animal model of menopause.

    PubMed

    Van Kempen, Tracey A; Milner, Teresa A; Waters, Elizabeth M

    2011-03-16

    Current rodent models of menopause fail to adequately recapitulate the menopause transition. The intact aging model fails to achieve very low estrogen levels, and the ovariectomy model lacks a perimenopause phase. A new rodent model of accelerated ovarian failure (AOF) successfully replicates human perimenopause and postmenopause, including estrous acyclicity and fluctuating, followed by undetectable, estrogen levels, and allows for the dissociation of the effects of hormone levels from the effects of aging. In this model, an ovotoxic chemical, 4-vinylcyclohexene diepoxide (VCD), selective for primary and primordial follicles, is injected intraperitonelly in animals for 15 days. As the mature follicle population is depleted through natural cycling, ovarian failure follows increasing periods of acyclity. Administered at low doses, VCD specifically causes apoptotic cell death of primordial follicles but does not affect other peripheral tissues, including the liver and spleen, nor does it affect brain inflammation markers. In addition to reducing confounds associated with genetic and surgical manipulations, the AOF model maintains the presence of ovarian tissue which importantly parallels to the menopause transition in humans. The VCD injection procedure can be applied to studies using transgenic or knockout mice strains, or in other disease-state models (e.g., ischemia, atherosclerosis, or diabetes). This AOF model of menopause will generate new insights into women's health particularly in determining the critical periods (i.e., a window of opportunity) during perimenopause for restoring ovarian hormones for the most efficacious effect on memory and mood disorders as well as other menopausal symptoms. PMID:21211517

  17. Accelerated Ovarian Failure: a novel, chemically-induced animal model of menopause

    PubMed Central

    Van Kempen, Tracey A.; Milner, Teresa A.; Waters, Elizabeth M.

    2011-01-01

    Current rodent models of menopause fail to adequately recapitulate the menopause transition. The intact aging model fails to achieve very low estrogen levels, and the ovariectomy model lacks a perimenopause phase. A new rodent model of Accelerated Ovarian Failure (AOF) successfully replicates human perimenopause and postmenopause, including estrous acyclicity and fluctuating, followed by undetectable, estrogen levels, and allows for the dissociation of the effects of hormone levels from the effects of aging. In this model, an ovotoxic chemical, 4-vinylcyclohexene diepoxide (VCD), selective for primary and primordial follicles, is injected intraperitonelly in animals for 15 days. As the mature follicle population is depleted through natural cycling, ovarian failure follows increasing periods of acyclity. Administered at low doses, VCD specifically causes apoptotic cell death of primordial follicles but does not affect other peripheral tissues, including the liver and spleen, nor does it cross the blood-brain barrier. In addition to reducing confounds associated with genetic and surgical manipulations, the AOF model maintains the presence of ovarian tissue which importantly parallels to the menopause transition in humans. The VCD injection procedure can be applied to studies using transgenic or knock-out mice strains, or in other disease-state models (e.g., ischemia, atherosclerosis, or diabetes). This AOF model of menopause will generate new insights into women's health particularly in determining the critical periods (i.e., a window of opportunity) during perimenopause for restoring ovarian hormones for the most efficacious effect on memory and mood disorders as well as other menopausal symptoms. PMID:21211517

  18. 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.

  19. 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. PMID:23637212

  20. 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

    2016-01-01

    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 major

  1. 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

  2. Salt-Induced Changes in Cardiac Phosphoproteome in a Rat Model of Chronic Renal Failure

    PubMed Central

    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. PMID:24945867

  3. 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 ...

  4. 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. PMID:26945437

  5. 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.

  6. 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

  7. Failure of semiclassical models to describe resistivity of nanometric, polycrystalline tungsten films

    SciTech Connect

    Choi, Dooho; Liu, Xuan; Schelling, Patrick K.; Coffey, Kevin R.; Barmak, Katayun

    2014-03-14

    The impact of electron scattering at surfaces and grain boundaries in nanometric polycrystalline tungsten (W) films was studied. A series of polycrystalline W films ranging in thickness from 10 to 310 nm and lateral grain size from 74 to 133 nm were prepared on thermally oxidized Si. The Fuchs-Sondheimer surface-scattering model and Mayadas-Shatzkes grain-boundary scattering model were employed for quantitative analyses. Predictions from the theoretical models were found to deviate systematically from the experimental data. Possible reasons for the failure of the theoretical models to describe the experimental data are explored. Finally, a discussion of the crucial features lacking from existing models is presented, along with possible avenues for improving the models to result in better agreement with experimental data.

  8. Failure of CMIP5 climate models in simulating post-1950 decreasing trend of Indian monsoon

    NASA Astrophysics Data System (ADS)

    Saha, Anamitra; Ghosh, Subimal; Sahana, A. S.; Rao, E. P.

    2014-10-01

    Impacts of climate change on Indian Summer Monsoon Rainfall (ISMR) and the growing population pose a major threat to water and food security in India. Adapting to such changes needs reliable projections of ISMR by general circulation models. Here we find that, majority of new generation climate models from Coupled Model Intercomparison Project phase5 (CMIP5) fail to simulate the post-1950 decreasing trend of ISMR. The weakening of monsoon is associated with the warming of Southern Indian Ocean and strengthening of cyclonic formation in the tropical western Pacific Ocean. We also find that these large-scale changes are not captured by CMIP5 models, with few exceptions, which is the reason of this failure. Proper representation of these highlighted geophysical processes in next generation models may improve the reliability of ISMR projections. Our results also alert the water resource planners to evaluate the CMIP5 models before using them for adaptation strategies.

  9. A brittle failure model for long-period seismic events recorded at Turrialba Volcano, Costa Rica

    NASA Astrophysics Data System (ADS)

    Eyre, Thomas S.; Bean, Christopher J.; De Barros, Louis; Martini, Francesca; Lokmer, Ivan; Mora, Mauricio M.; Pacheco, Javier F.; Soto, Gerardo J.

    2015-03-01

    A temporary seismic network, consisting of 23 broadband and six short-period stations, was installed in a dense network at Turrialba Volcano, Costa Rica, between 8 March and 4 May 2011. During this time 513 long-period (LP) events were observed. Due to their pulse-like waveforms, the hypothesis that the events are generated by a slow-failure mechanism, based on a recent new model by Bean et al. (2014), is tested. A significant number (107) of the LPs are jointly inverted for their source locations and mechanisms, using full-waveform moment tensor inversion. The locations are mostly shallow, with depths < 800 m below the active Southwest Crater. The results of the decompositions of the obtained moment tensor solutions show complex source mechanisms, composed of high proportions of isotropic and low, but seemingly significant, proportions of compensated linear vector dipole and double-couple components. It is demonstrated that this can be explained as mode I tensile fracturing with a strong shear component. The source mechanism is further investigated by exploring scaling laws within the data. The LPs recorded follow relationships very similar to those of conventional earthquakes, exhibiting frequency-magnitude and corner frequency versus magnitude relationships that can be explained by brittle failure. All of these observations indicate that a slow-failure source model can successfully describe the generation of short-duration LP events at Turrialba Volcano.

  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. 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.

  12. Laboratory investigation of borehole breakouts and Multi-step failure model

    NASA Astrophysics Data System (ADS)

    Ruan, Xiao-Ping; Mao, Ji-Zheng; Cui, Zhan-Tao

    1993-05-01

    Based on our experiment of borehole breakouts with a group of sandstone samples described in this paper, a multi-step failure model of borehole breakouts are proposed to quantitatively explain the relationship between the section shape of borehole breakouts and the state of crustal stress. In this model the borehole spalling is not only related to the state of stress at a single point but also the state of stress on its neighboring area. The comparison between the experimental results of borehole breakouts and the calculation results shows a good agreement.

  13. African swine fever.

    PubMed

    Penrith, Mary-Louise

    2009-03-01

    African swine fever (ASF) is a devastating haemorrhagic fever of pigs that causes up to 100% mortality, for which there is no vaccine. It is caused by a unique DNA virus that is maintained in an ancient cycle between warthogs and argasid ticks, making it the only known DNA arbovirus. ASF has a high potential for transboundary spread, and has twice been transported from Africa to other continents--Europe and subsequently the Caribbean and Brazil (1957, 1959) and the Caucasus (2007). It is also a devastating constraint for pig production in Africa. Research at Onderstepoort Veterinary Institute has made and is making important contributions to knowledge of this disease, focusing on the cycle in warthogs and tampans and transmission from that cycle to domestic pigs, resistance to its effects in domestic pigs, and the molecular genetic characterisation and epidemiology of the virus. PMID:19967933

  14. 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.

  15. 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. PMID:26875754

  16. 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.

  17. 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

    2015-01-01

    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 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. PMID:25813399

  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. 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.

  20. 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.

  1. 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 ...

  2. 2009 Swine Flu Originated in Mexico

    MedlinePlus

    ... https://medlineplus.gov/news/fullstory_159679.html 2009 Swine Flu Originated in Mexico Genetic analysis pinpoints source ... FRIDAY, July 1, 2016 (HealthDay News) -- The 2009 swine flu pandemic originated in pigs in a small ...

  3. Incremental and independent value of cardiopulmonary exercise test measures and the Seattle Heart Failure Model for prediction of risk in patients with heart failure

    PubMed Central

    Dardas, Todd; Li, Yanhong; Reed, Shelby D.; O’Connor, Christopher M.; Whellan, David J.; Ellis, Stephen J.; Schulman, Kevin A.; Kraus, William E.; Forman, Daniel E.; Levy, Wayne C.

    2016-01-01

    Background Multivariable risk scores and exercise measures are well-validated risk prediction methods. Combining information from a functional evaluation and a risk model may improve accuracy of risk predictions. We analyzed whether adding exercise measures to the Seattle Heart Failure Model (SHFM) improves risk prediction accuracy in systolic heart failure. Methods and Results We used a sample of patients from the Heart Failure and A Controlled Trial Investigating Outcomes of Exercise TraiNing (HF-ACTION) study to examine the addition of peak VO2, VE/VCO2 slope, 6-minute walk distance (6MWD) or exercise duration (CPXDUR) to the SHFM. Multivariable Cox proportional hazards models were used to test the association between the combined endpoint (death, LVAD or cardiac transplantation) and the addition of exercise variables to the SHFM. 2152 patients were included in the sample. The SHFM and all exercise measures were associated with events (all p-values<0.0001) in proportional hazards models. There was statistically significant improvement in risk estimation when exercise measures were added to the SHFM. However, the improvement in c-index for addition of peak VO2 (+0.01), VE/VCO2 (+0.02), 6MWD (−0.001) and CPXDUR (+0.001) to the SHFM was small or slightly worse than the SHFM alone. Changes in risk assignment with the addition of exercise variables were minimal for patients above or below a15% 1-year mortality. Conclusions Exercise performance measures and the SHFM are independently useful for predicting risk in systolic heart failure. Adding CPET measures and 6MWD to the SHFM offers only minimal improvement in risk reassignment at clinically meaningful cutpoints. PMID:25940075

  4. 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. PMID:26530136

  5. Modelling river bank retreat by combining fluvial erosion, seepage and mass failure

    NASA Astrophysics Data System (ADS)

    Dapporto, S.; Rinaldi, M.

    2003-04-01

    Streambank erosion processes contribute significantly to the sediment yielded from a river system and represent an important issue in the contexts of soil degradation and river management. Bank retreat is controlled by a complex interaction of hydrologic, geotechnical, and hydraulic processes. The capability of modelling these different components allows for a full reconstruction and comprehension of the causes and rates of bank erosion. River bank retreat during a single flow event has been modelled by combining simulation of fluvial erosion, seepage, and mass failures. The study site, along the Sieve River (Central Italy), has been subject to extensive researches, including monitoring of pore water pressures for a period of 4 years. The simulation reconstructs fairly faithfully the observed changes, and is used to: a) test the potentiality and discuss advantages and limitations of such type of methodology for modelling bank retreat; c) quantify the contribution and mutual role of the different processes determining bank retreat. The hydrograph of the event is divided in a series of time steps. Modelling of the riverbank retreat includes for each step the following components: a) fluvial erosion and consequent changes in bank geometry; b) finite element seepage analysis; c) stability analysis by limit equilibrium method. Direct fluvial shear erosion is computed using empirically derived relationships expressing lateral erosion rate as a function of the excess of shear stress to the critical entrainment value for the different materials along the bank profile. Lateral erosion rate has been calibrated on the basis of the total bank retreat measured by digital terrestrial photogrammetry. Finite element seepage analysis is then conducted to reconstruct the saturated and unsaturated flow within the bank and the pore water pressure distribution for each time step. The safety factor for mass failures is then computed, using the pore water pressure distribution obtained

  6. 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. PMID:26187243

  7. Effects of poverty on academic failure and delinquency in boys: a change and process model approach.

    PubMed

    Pagani, L; Boulerice, B; Vitaro, F; Tremblay, R E

    1999-11-01

    Using data from the Montreal Longitudinal-Experimental Study, we examined the impact of poverty (and its correlate, family configuration status) on academic placement and self-reported delinquency in boys at age 16. We then investigated whether the relation between family economic hardship and antisocial behaviour is direct or indirect by considering the value of parenting practices and academic failure as process variables in the model. Data included official records, and parent, teacher, and self-reports. The temporal intensity of poverty was classified into five categories: never-poor; always-poor; poor-earlier; poor-later; and transitory-poverty. Family configuration status was classified by both temporal characteristics and number of marital transitions: intact-family; short-term-single; long-term-single; short-term-remarried; long-term-remarried; and multiple-marital-transitions. Results revealed that when maternal education and early childhood behaviour were controlled, poverty had an effect on both academic failure and extreme delinquency. This effect was independent of family configuration status. Although they both significantly predicted extreme delinquency on their own, academic failure and parental supervision did not mediate the relationship between poverty and delinquency. Divorce increased the risk of theft and fighting at age 16, regardless of financial hardship. Parental supervision only helped explain the effects of divorce on boys' fighting. PMID:10604399

  8. 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.

  9. Modeling Block Failure in Vertical Cliffs of Arctic Coasts Underlain by Permafrost

    NASA Astrophysics Data System (ADS)

    Pollard, W. H.

    2004-12-01

    Arctic coasts lie at the interface between terrestrial systems dominated by permafrost, and marine systems that are characterized by long periods of ice cover and short periods of open water when wave action and storm activity are important. Permafrost, sea ice and wind-wave conditions are driven by regional and local climate forcing and interact in such a way that a change in one produces feedbacks affecting the other two. However, under predicted climate change scenarios of warming, increased storm activity and sea level rise will profoundly affect all three leading to potentially devastating rates of coastal erosion and permafrost degradation. Permafrost coasts are subject to complex erosional processes, however one of the most poorly understood but probably most important is block failure. Thermo-abrasional falls or block collapses provide the most spectacular form of coastal recession in permafrost areas. This study provides computational models for block failure mechanisms and investigates the relative contribution of horizontal thermo-erosional niches and ice wedges to block failure of permafrost cliffs fronted by a beach.

  10. 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

  11. 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.

  12. 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...

  13. THE CORONARY ARTERY HISTOPATHOLOGIC RESPONSE TO ANGIOPLASTY BALLOON INJURY IN A SWINE MODEL IS GENDER- AND HORMONAL-DEPENDENT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of gender and exogenous estrogen on the histopathologic response of the left anterior descending coronary artery (LAD) to angioplasty balloon over-inflation were examined in this study. In addition, we sought to develop an animal model to predict adequately the effects of cardiovascular ...

  14. Intracoronary infusion of autologous mononuclear cells from bone marrow or G-CSF mobilised apheresis product may not improve remodelling, contractile function, perfusion or infarct size in a swine model of large myocardial infarction

    PubMed Central

    de Silva, Ranil; Raval, Amish N.; Hadi, Mohiuddin; Gildea, Karena M.; Bonifacino, Aylin C.; Yu, Zu-Xi; Yau, Yu Ying; Leitman, Susan F.; Bacharach, Stephen L.; Donahue, Robert E.; Read, Elizabeth J.; Lederman, Robert J.

    2008-01-01

    Background In a blinded, placebo controlled study, we investigated whether intracoronary infusion of autologous mononuclear cells from G-CSF mobilised apheresis product or bone marrow (BM) improved sensitive outcome measures in a swine model of large MI. Methods and Results Four days after LAD occlusion and reperfusion, cells from BM or apheresis product of saline (Placebo) or G-CSF injected animals were infused into the LAD. Large infarcts were created: baseline ejection fraction (EF) by MRI of 35.3 ± 8.5%, no difference between the Placebo, G-CSF and BM groups (p=0.16 by ANOVA). At 6 weeks EF fell to a similar degree in the Placebo, G-CSF and BM groups (−7.9±6.0%, −8.5±8.8% and −10.9±7.6%, p=0.78 by ANOVA). Left ventricular volumes and infarct size by MRI deteriorated similarly in all 3 groups. Quantitative PET demonstrated significant decline in FDG uptake rate in the LAD territory at follow-up, with no histological, angiographic or PET perfusion evidence of functional neovascularisation. Immunofluorescence failed to demonstrate transdifferentiation of infused cells. Conclusion Intracoronary infusion of mononuclear cells from either bone marrow or G-CSF mobilised apheresis product may not improve or limit deterioration in systolic function, adverse ventricular remodelling, infarct size or perfusion in a swine model of large MI. PMID:18502738

  15. 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

  16. 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.

  17. 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...

  18. 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,...

  19. 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...

  20. 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,...

  1. 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,...

  2. 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,...

  3. 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...

  4. H1N1 influenza (Swine flu)

    MedlinePlus

    Swine flu; H1N1 type A influenza ... of the H1N1 virus were found in pigs (swine). Over time, the virus changed (mutated) and infected ... 25654610 . Treanor JJ. Influenza (including avian influenza and swine influenza). In: Bennett JE, Dolin R, Blaser MJ, ...

  5. 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...

  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, 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...

  8. The effects of dobutamine, propranolol and nitroglycerin on an experimental canine model of congestive heart failure.

    PubMed

    Kamijo, T; Tomaru, T; Miwa, A Y; Nakamura, F; Kido, H; Sugimoto, T; Uchida, Y

    1994-07-01

    A new experimental model of acute congestive heart failure was established in open-chest dogs, and it was employed to examine the effects of dobutamine, propranolol and nitroglycerin. The model was induced by intracoronary administration of saponin, volume loading and intravenous infusion of methoxamine. Left ventricular end-diastolic pressure (LVEDP) increased from 7.9 +/- 0.6 to 24.2 +/- 1.4 mmHg, and aortic blood flow (AoF) decreased from 0.89 +/- 0.06 to 0.53 +/- 0.04 l/min. Systemic vascular resistance (SVR) increased from 9618 +/- 585 to 16492 +/- 1213 dynes.sec/cm5 and right atrial pressure (RAP) increased from 2.5 +/- 0.2 to 4.2 +/- 0.4 mmHg. Furthermore, Vmax decreased from 71.6 +/- 5.1 to 45.8 +/- 2.9 1/sec, and the time constant of left ventricular pressure decay (T) increased from 40.0 +/- 2.6 to 90.2 +/- 7.9 msec. These hemodynamic changes were stable for up to 80 min. Dobutamine improved cardiac function by increasing Vmax and by decreasing T. Consequently, dobutamine increased AoF and decreased LVEDP, while there was no change in SVR. Nitroglycerin reduced LVEDP, SVR and T; increased AoF; and did not change Vmax. Propranolol produced no improvement in the hemodynamics or cardiac function. These results indicate that the present congestive heart failure model is characterized by global left ventricular dysfunction with lowered cardiac output and increased peripheral vascular tone, and it is beneficial for evaluating the pharmacological properties of drugs for acute congestive heart failure. PMID:7799523

  9. Integrated Simulation Linked with Failure Models for Highly Reliable Design of Liquid Rocket Engine

    NASA Astrophysics Data System (ADS)

    Iwasaki, Fumiya; Kuratani, Naoshi; Aoki, Hiroshi; Kawamata, Yoshihiro; Kure, Hirotaka; Satoh, Shinichi

    Recently, the new design method is required to predict "system reliability level" at the conceptual design phase, to grasp and to optimize the distribution of "risks and margins" because attainable "system reliability level" strongly depends on its basic concept. This paper describes a sample approach to measure "system reliability level", focusing on analytical modeling of failure mechanism and rocket engine steady-state or dynamic simulator. Some design parameters are picked up to understand where and how their dispersion makes an effect in the whole engine system performance or reliability, and to control the total system robustness.

  10. 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.

  11. Monitoring the influence of compression therapy on pathophysiology and structure of a swine scar model using multispectral imaging system

    NASA Astrophysics Data System (ADS)

    Ghassemi, Pejhman; Travis, Taryn E.; Shuppa, Jeffrey W.; Moffatt, Lauren T.; Ramella-Romana, Jessica C.

    2014-03-01

    Scar contractures can lead to significant reduction in function and inhibit patients from returning to work, participating in leisure activities and even render them unable to provide care for themselves. Compression therapy has long been a standard treatment for scar prevention but due to the lack of quantifiable metrics of scar formation scant evidence exists of its efficacy. We have recently introduced a multispectral imaging system to quantify pathophysiology (hemoglobin, blood oxygenation, melanin, etc) and structural features (roughness and collagen matrix) of scar. In this study, hypertrophic scars are monitored in-vivo in a porcine model using the imaging system to investigate influence of compression therapy on its quality.

  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. Swine Flu -A Comprehensive View

    NASA Astrophysics Data System (ADS)

    Singh, Vandana; Sood, Meenakshi

    2012-07-01

    The present article is aimed on comprehensive view of Swine flu. It was first isolated from pigs in 1930 in USA. Pandemic caused by H1N1 in 2009 brought it in limelight. Itís a viral respiratory disease caused by viruses that infects pigs, resulting in nasal secretions, barking cough, decreased appetite, and listless behavior. Swine virus consist of eight RNA strands, one strand derived from human flu strains, two from avian (bird) strains, and five from swine strains. Swine flu spreads from infected person to healthy person by inhalation or ingestion of droplets contaminated with virus while sneezing or coughing. Two antiviral agents have been reported to help prevent or reduce the effects of swine flu, flu shot and nasal spray. WHO recommended for pandemic period to prevent its future outbreaks through vaccines or non-vaccines means. Antiviral drugs effective against this virus are Tamiflu and Relenza. Rapid antigen testing (RIDT), DFA testing, viral culture, and molecular testing (RT-PCR) are used for its diagnosis in laboratory

  15. Pulmonary Thermal Ablation: Comparison of Radiofrequency and Microwave Devices by Using Gross Pathologic and CT Findings in a Swine Model

    PubMed Central

    Brace, Christopher L.; Hinshaw, J. Louis; Laeseke, Paul F.; Sampson, Lisa A.; Lee, Fred T.

    2009-01-01

    Purpose: To compare the performance of equivalently sized radiofrequency and microwave ablation applicators in a normal porcine lung model. Materials and Methods: All experiments were approved by an institutional animal care and use committee. A total of 18 ablations were performed in vivo in normal porcine lungs. By using computed tomographic (CT) fluoroscopic guidance, a 17-gauge cooled triaxial microwave antenna (n = 9) and a 17-gauge cooled radiofrequency (RF) electrode (n = 9) were placed percutaneously. Ablations were performed for 10 minutes by using either 125 W of microwave power or 200 W of RF power delivered with an impedance-based pulsing algorithm. CT images were acquired every minute during ablation to monitor growth. Animals were sacrificed after the procedure. Ablation zones were then excised and sectioned transverse to the applicator in 5-mm increments. Minimum and maximum diameter, cross-sectional area, length, and circularity were measured from gross specimens and CT images. Comparisons of each measurement were performed by using a mixed-effects model; P < .05 was considered to indicate a significant difference. Results: Mean diameter (3.32 cm ± 0.19 [standard deviation] vs 2.70 cm ± 0.23, P < .001) was 25% larger with microwave ablation and mean cross-sectional area (8.25 cm2 ± 0.92 vs 5.45 cm2 ± 1.14, P < .001) was 50% larger with microwave ablation, compared with RF ablation. With microwave ablation, the zones of ablation were also significantly more circular in cross section (mean circularity, 0.90 ± 0.06 vs 0.82 ± 0.09; P < .05). One small pneumothorax was noted during RF ablation but stabilized without intervention. Conclusion: Microwave ablation with a 17-gauge high-power triaxial antenna creates larger and more circular zones of ablation than does a similarly sized RF applicator in a preclinical animal model. Microwave ablation may be a more effective treatment of lung tumors. © RSNA, 2009 PMID:19336667

  16. Modeling the failure of magmatic foams with application to Stromboli volcano, Italy

    NASA Astrophysics Data System (ADS)

    O'Shaughnessy, Cedrick; Brun, Francesco; Mancini, Lucia; Fife, Julie L.; Baker, Don R.

    2014-10-01

    The failure of magmatic foams has been implicated as a fundamental process in eruptions occurring at open-conduit, basaltic volcanoes. In order to investigate the failure of magmatic foams we applied the fiber bundle model using global load sharing. The strengths of the fibers for the model were taken from bubble wall widths measured in four computer-simulated foams of low-porosity and from one very low-porosity and two high-porosity foams produced in the laboratory by heating hydrated basaltic glasses to 1200 °C. The relative strength of an individual fiber in the model was calculated from the square of a bubble wall's average width and absolute strengths of the foams were calculated based upon the correlation of the strength of one modeled foam with experimental data. The fiber bundle model is shown to successfully reproduce measured tensile strengths of porous volcanic rocks studied by other researchers and confirms previous 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. Because of the success of the fiber bundle model in reproducing experimental foam failure, its results are compared to infrasonic measurements associated with bubbles at Stromboli (Italy) and demonstrate that within uncertainty the power-law exponents of the infrasonic energies and of the fiber bundle model energies are in agreement; both show a crossover 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 and are interpreted to reflect the bursting of multitudes of small bubbles, rather than a few large bubbles. The

  17. 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...

  18. EFFECT OF RENAL SHOCK WAVE LITHOTRIPSY ON THE DEVELOPMENT OF METABOLIC SYNDROME IN A JUVENILE SWINE MODEL: A PILOT STUDY

    PubMed Central

    Handa, Rajash K.; Liu, Ziyue; Connors, Bret A.; Evan, Andrew P.; Lingeman, James E.; Basile, David P.; Tune, Johnathan D.

    2014-01-01

    Purpose A pilot study was conducted to assess whether renal shock wave lithotripsy (SWL) influences the onset and severity of metabolic syndrome (MetS). Materials and Methods Three-month-old juvenile female Ossabaw miniature pigs were treated with SWL (2000 SWs, 24 kV, 120 SWs/min using the HM3 lithotripter; n=2) or sham-SWL (no SWs; n=2). SWs were targeted to the upper pole of the left kidney so as to model treatment that would also expose the pancreatic tail to SWs. Pigs were then instrumented for direct measurement of arterial blood pressure via an implanted radiotelemetry device, and later fed a hypercaloric atherogenic diet for ~7 months. The development of MetS was assessed from intravenous glucose tolerance tests (IVGTTs). Results The progression and severity of MetS was similar in the sham-treated and SWL-treated groups. The only exception was with respect to arterial blood pressure, which remained relatively constant in the sham-treated pigs but began to rise at ~2 months towards hypertensive levels in SW-treated pigs. Metabolic data from both groups were pooled to provide a more complete assessment of the development and progression of MetS in this juvenile pig model. IVGTTs revealed substantial insulin resistance with impaired glucose tolerance within 2 months on the hypercaloric atherogenic diet with signs of further metabolic impairment at 7 months. Conclusions These preliminary results suggest that renal SWL is not a risk factor for worsening of glucose tolerance or the onset of diabetes mellitus, but does appear to be a risk factor for early onset hypertension in MetS. PMID:25245490

  19. Failure behavior of internally pressurized flawed and unflawed steam generator tubing at high temperatures -- Experiments and comparison with model predictions

    SciTech Connect

    Majumdar, S.; Shack, W.J.; Diercks, D.R.; Mruk, K.; Franklin, J.; Knoblich, L.

    1998-03-01

    This report summarizes experimental work performed at Argonne National Laboratory on the failure of internally pressurized steam generator tubing at high temperatures ({le} 700 C). A model was developed for predicting failure of flawed and unflawed steam generator tubes under internal pressure and temperature histories postulated to occur during severe accidents. The model was validated by failure tests on specimens with part-through-wall axial and circumferential flaws of various lengths and depths, conducted under various constant and ramped internal pressure and temperature conditions. The failure temperatures predicted by the model for two temperature and pressure histories, calculated for severe accidents initiated by a station blackout, agree very well with tests performed on both flawed and unflawed specimens.

  20. A mechanism based modeling approach to failure in fiber reinforced composites

    NASA Astrophysics Data System (ADS)

    Yerramalli, Chandra Sekher

    The increasing use of fiber reinforced polymer composites (FRPC) in civil and military applications has made it imperative that the behavior of FRPC be understood under a variety of loading conditions. It is known that the compressive load carrying capacity of FRPC is low compared to its tensile load carrying capacity. Thus, the compressive behavior of FRPC has been a limiting factor in the design of FRPC structures. In the current work, the compressive behavior of FRPC has been studied with an aim to identify and understand the important parameters affecting the compressive strength and failure mechanisms in FRPC, particularly under combined stress states. The purpose is to establish compressive strength degradation (or enhancement) in the presence of combined stress states. Results from experiments have led to the development of a mechanism based failure model, based on the principles of fracture mechanics for the splitting failure of FRPC. A mechanics model has been developed for both pure compression and combined compression-torsion loading. The predictions of the model were found to compare favorably with experimental data obtained from glass and carbon FRPC under pure compression and combined compression-torsion loading. A 3D finite element simulation of a representative cylindrical section of the composite was performed. The results indicated the importance of fiber diameter on the predicted compressive response of the composite. It also indicated the possibilities of fiber breakage under axial loading as a cause for the initiation of kinking in case of small diameter fiber reinforced composites. Pure compression tests were also conducted on hybrid (glass/carbon) composites under static and dynamic loading conditions. The static compressive strength of hybrid composites shows a non-monotonic behavior with respect to the hybrid ratio. The compressive strength first decreases and then increases as we approach either pure carbon or pure glass composites. The

  1. Hepatoprotective effect of nitric oxide in experimental model of acute hepatic failure

    PubMed Central

    Saracyn, Marek; Brytan, Marek; Zdanowski, Robert; Ząbkowski, Tomasz; Dyrla, Przemysław; Patera, Janusz; Wojtuń, Stanisław; Kozłowski, Wojciech; Wańkowicz, Zofia

    2014-01-01

    AIM: To evaluate the effect of nitric oxide (NO) on the development and degree of liver failure in an animal model of acute hepatic failure (AHF). METHODS: An experimental rat model of galactosamine-induced AHF was used. An inhibitor of NO synthase, nitroarginine methyl ester, or an NO donor, arginine, were administered at various doses prior to or after the induction of AHF. RESULTS: All tested groups developed AHF. Following inhibition of the endogenous NO pathway, most liver parameters improved, regardless of the inhibitor dose before the induction of liver damage, and depending on the inhibitor dose after liver damage. Prophylactic administration of the inhibitor was more effective in improving liver function parameters than administration of the inhibitor after liver damage. An attempt to activate the endogenous NO pathway prior to the induction of liver damage did not change the observed liver function parameters. Stimulation of the endogenous NO pathway after liver damage, regardless of the NO donor dose used, improved most liver function parameters. CONCLUSION: The endogenous NO pathway plays an important role in the development of experimental galactosamine-induced AHF. PMID:25516652

  2. Patient-specific modeling of dyssynchronous heart failure: a case study.

    PubMed

    Aguado-Sierra, Jazmin; Krishnamurthy, Adarsh; Villongco, Christopher; Chuang, Joyce; Howard, Elliot; Gonzales, Matthew J; Omens, Jeff; Krummen, David E; Narayan, Sanjiv; Kerckhoffs, Roy C P; McCulloch, Andrew D

    2011-10-01

    The development and clinical use of patient-specific models of the heart is now a feasible goal. Models have the potential to aid in diagnosis and support decision-making in clinical cardiology. Several groups are now working on developing multi-scale models of the heart for understanding therapeutic mechanisms and better predicting clinical outcomes of interventions such as cardiac resynchronization therapy. Here we describe the methodology for generating a patient-specific model of the failing heart with a myocardial infarct and left ventricular bundle branch block. We discuss some of the remaining challenges in developing reliable patient-specific models of cardiac electromechanical activity, and identify some of the main areas for focusing future research efforts. Key challenges include: efficiently generating accurate patient-specific geometric meshes and mapping regional myofiber architecture to them; modeling electrical activation patterns based on cellular alterations in human heart failure, and estimating regional tissue conductivities based on clinically available electrocardiographic recordings; estimating unloaded ventricular reference geometry and material properties for biomechanical simulations; and parameterizing systemic models of circulatory dynamics from available hemodynamic measurements. PMID:21763714

  3. 9 CFR 166.6 - Swine feeding area standards.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Swine feeding area standards. 166.6... AGRICULTURE SWINE HEALTH PROTECTION SWINE HEALTH PROTECTION General Provisions § 166.6 Swine feeding area standards. Untreated garbage shall not be allowed into swine feeding areas. Any equipment or...

  4. 9 CFR 93.505 - Certificate for swine.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Certificate for swine. 93.505 Section... FOR MEANS OF CONVEYANCE AND SHIPPING CONTAINERS Swine § 93.505 Certificate for swine. (a) All swine... veterinarian issuing the certificate was authorized to do so, stating that such swine have been kept in...

  5. 9 CFR 166.6 - Swine feeding area standards.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Swine feeding area standards. 166.6... AGRICULTURE SWINE HEALTH PROTECTION SWINE HEALTH PROTECTION General Provisions § 166.6 Swine feeding area standards. Untreated garbage shall not be allowed into swine feeding areas. Any equipment or...

  6. 9 CFR 93.505 - Certificate for swine.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Certificate for swine. 93.505 Section... FOR MEANS OF CONVEYANCE AND SHIPPING CONTAINERS Swine § 93.505 Certificate for swine. (a) All swine... veterinarian issuing the certificate was authorized to do so, stating that such swine have been kept in...

  7. 9 CFR 166.6 - Swine feeding area standards.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Swine feeding area standards. 166.6... AGRICULTURE SWINE HEALTH PROTECTION SWINE HEALTH PROTECTION General Provisions § 166.6 Swine feeding area standards. Untreated garbage shall not be allowed into swine feeding areas. Any equipment or...

  8. 9 CFR 166.6 - Swine feeding area standards.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Swine feeding area standards. 166.6... AGRICULTURE SWINE HEALTH PROTECTION SWINE HEALTH PROTECTION General Provisions § 166.6 Swine feeding area standards. Untreated garbage shall not be allowed into swine feeding areas. Any equipment or...

  9. 9 CFR 166.6 - Swine feeding area standards.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Swine feeding area standards. 166.6... AGRICULTURE SWINE HEALTH PROTECTION SWINE HEALTH PROTECTION General Provisions § 166.6 Swine feeding area standards. Untreated garbage shall not be allowed into swine feeding areas. Any equipment or...

  10. 9 CFR 93.505 - Certificate for swine.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Certificate for swine. 93.505 Section... FOR MEANS OF CONVEYANCE AND SHIPPING CONTAINERS Swine § 93.505 Certificate for swine. (a) All swine... veterinarian issuing the certificate was authorized to do so, stating that such swine have been kept in...

  11. 9 CFR 93.505 - Certificate for swine.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Certificate for swine. 93.505 Section... FOR MEANS OF CONVEYANCE AND SHIPPING CONTAINERS Swine § 93.505 Certificate for swine. (a) All swine... veterinarian issuing the certificate was authorized to do so, stating that such swine have been kept in...

  12. 9 CFR 93.505 - Certificate for swine.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Certificate for swine. 93.505 Section... FOR MEANS OF CONVEYANCE AND SHIPPING CONTAINERS Swine § 93.505 Certificate for swine. (a) All swine... veterinarian issuing the certificate was authorized to do so, stating that such swine have been kept in...

  13. Representational models associated with fear of failure in adolescents and young adults.

    PubMed

    Conroy, David E

    2003-10-01

    As a descriptive trait, fear of failure (FF) has been associated with serious problems in achievement and health. Psychodynamic theories emphasizing interpersonal processes and early object relations are often used to explain the etiology of FF despite little comprehensive research on such theories in the FF domain. The present study employed the Structural Analysis of Social Behavior to study associations between FF and representational models of self and others among 211 high school and college-aged students and athletes. FF was strongly associated with hostile representational models of self while failing (large effect size). This hostility paralleled the manner in which high FF participants reported being treated by their parents and most significant instructors (all moderate effect sizes). Overall, results supported the complementary nature of these theoretical perspectives and provided further evidence for interpersonal theories of FF. PMID:12932209

  14. GAUGE RUN-TO-DETONATION DATA AND FAILURE/DEAD ZONE MODELING

    SciTech Connect

    Souers, P C; Vitello, P; Vandersall, K S

    2009-06-26

    Previous shock initiation run-to-detonation experiments on energetic materials were plotted with distance and time to get a single distance/time to detonation. Modern shots utilize enough gauges so that the distance-time data can be differentiated, which shows not only the usual inflection pressure point before detonation, referred to here as P{sub b}, but also a second, low-pressure inflection, referred to here as P{sub a}, that marks rapid ramp-up of the initiation. An analysis of the TATB based LX-17 and PBX 9502 in addition to the LLM-105 based RX-55 data shows that both P{sub a} and P{sub b} increase linearly with the initiation pressure created by the flyer plate. This contradicts the current method in the Tarantula failure/dead zone model, which uses constant pressure boundaries between reaction regions. Modeling changes required by the new data will be considered.

  15. Finite Element Modeling of the Different Failure Mechanisms of a Plasma Sprayed Thermal Barrier Coatings System

    NASA Astrophysics Data System (ADS)

    Ranjbar-Far, M.; Absi, J.; Mariaux, G.

    2012-12-01

    A new finite element model is used to investigate catastrophic failures of a thermal barrier coatings system due to crack propagation along the interfaces between the ceramic top-coat, thermally grown oxide, and bond-coat layers, as well as between the lamellas structure of the ceramic layer. The thermo-mechanical model is designed to take into account a non-homogenous temperature distribution and the effects of the residual stresses generated during the coating process. Crack propagation is simulated using the contact tool "Debond" present in the ABAQUS finite element code. Simulations are performed with a geometry corresponding to similar or dissimilar amplitudes of asperity, and for different thicknesses of the oxide layer. The numerical results have shown that crack evolution depends crucially on the ratio of the loading rate caused by growth and swelling of the oxide layer and also on the interface roughness obtained during the spraying of coatings.

  16. A general model for predicting coolant activity behaviour for fuel-failure monitoring analysis

    NASA Astrophysics Data System (ADS)

    El-Jaby, A.; Lewis, B. J.; Thompson, W. T.; Iglesias, F.; Ip, M.

    2010-04-01

    A mathematical treatment has been developed to predict the release of volatile fission products from operating defective nuclear fuel elements. The fission product activity in both the fuel-to-sheath gap and primary heat transport system as a function of time can be predicted during all reactor operating conditions, including: startup, steady-state, shutdown, and bundle-shifting manoeuvres. In addition, an improved ability to predict the coolant activity of the 135Xe isotope in commercial reactors is discussed. A method is also proposed to estimate both the burnup and the amount of tramp uranium deposits in-core. The model has been validated against in-reactor experiments conducted with defective fuel elements containing natural and artificial failures at the Chalk River Laboratories. Lastly, the model has been benchmarked against a defective fuel occurrence in a commercial reactor.

  17. Modeling and Prediction of Thermal Cycle Induced Failure in Epoxy-Silica Composites

    NASA Astrophysics Data System (ADS)

    Kmita, Grzegorz; Nowak, Tomasz; Sekula, Robert

    2012-02-01

    Epoxy resins filled with dielectric mineral particles are frequently used as insulating materials in power industry applications. Due to their excellent dielectric properties and relatively good thermal performance (resistance, ageing and conductivity) their usability is common and extensive. However, the mechanical performance of the resins is influenced by several factors such as resistance to crack propagation, especially in low temperature applications. This phenomenon is normally linked with appearance of two phase systems where particle filled epoxy material interacts with metallic inserts having significantly different thermal expansion coefficients. This kind of epoxy-metal interface can produce relatively high stresses in the product structure during thermal cycle loading. The paper deals with mechanical problems of power industry products and introduces the methodology for numerical modeling of failure in silica filled epoxy systems subjected to severe temperature gradients. Various aspects of material behavior modeling are covered in this article, including polymerization process, viscoelastic stress relaxation as well as stochastic cracking.

  18. Hamiltonian-Based Model to Describe the Nonlinear Physics of Cascading Failures in Power-Grid Networks

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Motter, Adilson

    A local disturbance to the state of a power-grid system can trigger a protective response that disables some grid components, which leads to further responses, and may finally result in large-scale failures. In this talk, I will introduce a Hamiltonian-like model of cascading failures in power grids. This model includes the state variables of generators, which are determined by the nonlinear swing equations and power-flow equations, as well as the on/off status of the network components. This framework allows us to view a cascading failure in the power grid as a phase-space transition from a fixed point with high energy to a fixed point with lower energy. Using real power-grid networks, I will demonstrate that possible cascade outcomes can be predicted by analyzing the stability of the system's equilibria. This work adds an important new dimension to the current understanding of cascading failures.

  19. Failure process and hydrologic response of a two layer physical model: Implications for rainfall-induced landslides

    NASA Astrophysics Data System (ADS)

    Lourenço, Sérgio D. N.; Sassa, Kyoji; Fukuoka, Hiroshi

    2006-01-01

    Field observations and theoretical analysis have been used in the literature to assess slope instability caused by permeability variations. This investigation aims to study the influence of permeability variations on slope behaviour by experimental means. It focuses particularly on the pore water pressure generation in the vicinity of soils with different permeabilities, and the corresponding failure mode. A series of generated failures in a model with 2 soil layers was performed by means of a flume device. The soil layers were made of a medium-sized sand and a fine sand, placed in horizontal layers. A combination of photography and pore water pressure measurements was used to examine the relationship between the pore water pressure generation and failure modes. Experiments were conducted for different arrangements of soil layers (by changing the soil layer position), and infiltration direction ( downward infiltration by sprinkling water on the soil, and upward infiltration from the bottom of the lower soil layer). The results revealed no clear link between the failure mode and recorded pore water pressure. Instead, the failure mode was seen to depend mostly on the relative layer position, and the recorded pore water pressures on the imposed infiltration direction. Failure was not confined to a single failure mode, but ranged instead from retrogressive slides and lateral spreads to seepage erosion. Regarding the hydrologic response, interesting results were recorded for experiments performed by downward infiltration, where perched water tables were formed. The granular nature of both soils and the absence of an impermeable barrier at the downslope end of the model seem to have favoured water seepage as the controlling failure mechanism, enhancing seepage erosion and sliding, and restricting other failure modes that require a high soil saturation such as flow failure. As the drainage conditions were not controlled, these experiments provided a unique opportunity to

  20. Overview of Classical Swine Fever (Hog Cholera, Classical Swine fever)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Classical swine fever is a contagious often fatal disease of pigs clinically characterized by high body temperature, lethargy, yellowish diarrhea, vomits and purple skin discoloration of ears, lower abdomen and legs. It was first described in the early 19th century in the USA. Later, a condition i...

  1. Vasodilator effects of nebivolol in a rat model of hypertension and a rabbit model of congestive heart failure.

    PubMed

    de Groot, Annemieke A; Mathy, Marie-Jeanne; van Zwieten, Pieter A; Peters, Stephan L M

    2007-07-01

    Both hypertension and congestive heart failure are characterized by a reduced vasodilatory capacity. In both conditions, the impairment of endothelial function is mainly the result of a reduced nitric oxide availability. The highly beta1-selective third-generation adrenoceptor blocker nebivolol displays additional endothelium-dependent vasodilating actions in humans as well as in animal models. In this study, we investigated whether these vasodilating properties of nebivolol are preserved in conditions with endothelial dysfunction. The vasodilatory effects of nebivolol were compared with those of the muscarinic agonist methacholine in isolated aortic rings obtained from spontaneous hypertensive rats and rabbits with experimental heart failure. The methacholine-induced responses were attenuated in aortic rings from both spontaneous hypertensive rats and congestive heart failture rabbits (42+/-6% and 25+/-3% vs. 89+/-3% and 54+/-7% for controls, respectively; P<0.05, n=6-13), indicating an endothelial dysfunction in these preparations. In contrast, nebivolol-induced vasorelaxation remained unaffected in both preparations when compared to control preparations (40+/-12% and 43+/-6% vs. 52+/-8% and 50+/-13% for controls, respectively; P>0.05, n=6-13). These results implicate that the favorable hemodynamic profile of nebivolol may be preserved in patients with hypertension or congestive heart failure despite an impaired endothelial function. PMID:17666916

  2. A multi-objective optimisation model for sewer rehabilitation considering critical risk of failure.

    PubMed

    Ward, Ben; Savić, Dragan A

    2012-01-01

    A unique methodology for the optimal specification of sewer rehabilitation investment is presented in this paper. By accounting for the critical risk of asset failure, this methodology builds on previously successful work which explored the application of multi-objective optimisation tools to assist engineers with the specification of optimal rehabilitation strategies. The conventional sewerage rehabilitation specification process relies on the expertise of professional engineers to manually evaluate CCTV inspection information when determining the nature and extent of the rehabilitation solution. This process is not only tedious and subjective but it has no quantifiable means of identifying optimal solutions or possible combinations of optimal solutions in the delivery of catchment wide rehabilitation programmes. Therefore, the purely manual process of sewer rehabilitation design leaves a number of unanswered questions, such as: (1) Does the solution offer the greatest structural benefit to the network? (2) Is the solution the most cost-effective solution available? (3) Does the solution most greatly reduce the risk of critical asset failure? The application of a multi-objective genetic algorithm optimisation model, coupled with an enhanced critical risk methodology, has successfully answered these questions when applied to a case study data set provided by South West Water (UK). PMID:23032772

  3. Modeling Geometry and Progressive Failure of Material Interfaces in Plain Weave Composites

    NASA Technical Reports Server (NTRS)

    Hsu, Su-Yuen; Cheng, Ron-Bin

    2010-01-01

    A procedure combining a geometrically nonlinear, explicit-dynamics contact analysis, computer aided design techniques, and elasticity-based mesh adjustment is proposed to efficiently generate realistic finite element models for meso-mechanical analysis of progressive failure in textile composites. In the procedure, the geometry of fiber tows is obtained by imposing a fictitious expansion on the tows. Meshes resulting from the procedure are conformal with the computed tow-tow and tow-matrix interfaces but are incongruent at the interfaces. The mesh interfaces are treated as cohesive contact surfaces not only to resolve the incongruence but also to simulate progressive failure. The method is employed to simulate debonding at the material interfaces in a ceramic-matrix plain weave composite with matrix porosity and in a polymeric matrix plain weave composite without matrix porosity, both subject to uniaxial cyclic loading. The numerical results indicate progression of the interfacial damage during every loading and reverse loading event in a constant strain amplitude cyclic process. However, the composites show different patterns of damage advancement.

  4. Methanobactin reverses acute liver failure in a rat model of Wilson disease.

    PubMed

    Lichtmannegger, Josef; Leitzinger, Christin; Wimmer, Ralf; Schmitt, Sabine; Schulz, Sabine; Kabiri, Yaschar; Eberhagen, Carola; Rieder, Tamara; Janik, Dirk; Neff, Frauke; Straub, Beate K; Schirmacher, Peter; DiSpirito, Alan A; Bandow, Nathan; Baral, Bipin S; Flatley, Andrew; Kremmer, Elisabeth; Denk, Gerald; Reiter, Florian P; Hohenester, Simon; Eckardt-Schupp, Friedericke; Dencher, Norbert A; Adamski, Jerzy; Sauer, Vanessa; Niemietz, Christoph; Schmidt, Hartmut H J; Merle, Uta; Gotthardt, Daniel Nils; Kroemer, Guido; Weiss, Karl Heinz; Zischka, Hans

    2016-07-01

    In Wilson disease (WD), functional loss of ATPase copper-transporting β (ATP7B) impairs biliary copper excretion, leading to excessive copper accumulation in the liver and fulminant hepatitis. Current US Food and Drug Administration- and European Medicines Agency-approved pharmacological treatments usually fail to restore copper homeostasis in patients with WD who have progressed to acute liver failure, leaving liver transplantation as the only viable treatment option. Here, we investigated the therapeutic utility of methanobactin (MB), a peptide produced by Methylosinus trichosporium OB3b, which has an exceptionally high affinity for copper. We demonstrated that ATP7B-deficient rats recapitulate WD-associated phenotypes, including hepatic copper accumulation, liver damage, and mitochondrial impairment. Short-term treatment of these rats with MB efficiently reversed mitochondrial impairment and liver damage in the acute stages of liver copper accumulation compared with that seen in untreated ATP7B-deficient rats. This beneficial effect was associated with depletion of copper from hepatocyte mitochondria. Moreover, MB treatment prevented hepatocyte death, subsequent liver failure, and death in the rodent model. These results suggest that MB has potential as a therapeutic agent for the treatment of acute WD. PMID:27322060

  5. Physical modelling of rainfall-induced flow failures in loose granular soils

    NASA Astrophysics Data System (ADS)

    Take, W. A.; Beddoe, R. A.

    2015-09-01

    The tragic consequences of the March 2014 Oso landslide in Washington, USA were particularly high due to the mobility of the landslide debris. Confusingly, a landslide occurred at that exact same location a number of years earlier, but simply slumped into the river at the toe of the slope. Why did these two events differ so drastically in their mobility? Considerable questions remain regarding the conditions required to generate flow failures in loose soils. Geotechnical centrifuge testing, in combination with high-speed cameras and advanced image analysis has now provided the landslides research community with a powerful new tool to experimentally investigate the complex mechanics leading to high mobility landslides. This paper highlights recent advances in our understanding of the process of static liquefaction in loose granular soil slopes achieved through observations of highly-instrumented physical models. In particular, the paper summarises experimental results aimed to identify the point of initiation of the chain-reaction required to trigger liquefaction flow failures, to assess the effect of slope inclination on the likelihood of a flowslide being triggered, and to quantify the effect of antecedent groundwater levels on the distal reach of landslide debris with the objective of beginning to explain why neighbouring slopes can exhibit such a wide variation in landslide travel distance upon rainfall-triggering.

  6. Group Dynamics in Top Management Teams: Groupthink, Vigilance, and Alternative Models of Organizational Failure and Success.

    PubMed

    Peterson; Owens; Tetlock; Fan; Martorana

    1998-02-01

    This study explored the heuristic value of Janis' (1982) groupthink and vigilant decision making models as explanations of failure and success in top management team decision making using the Organizational Group Dynamics Q-sort (GDQ). Top management teams of seven Fortune 500 companies were examined at two historical junctures-one when the team was successful (defined as satisfying strategic constituencies) and one when the team was unsuccessful. Results strongly supported the notion that a group' decision making process is systematically related to the outcomes experienced by the team. Ideal-type Q-sorts organized around Janis' analysis of groupthink and vigilance were substantially correlated with Q-sorts of failing and successful groups, respectively. The fit was, however, far from perfect. Ideal-type Q-sorts derived from other frameworks correlated better with the failure-success classification than did the Janis-derived ideal types. Successful groups showed some indicators of groupthink (e.g., risk-taking, cohesion, and strong, opinionated leaders), whereas unsuccessful groups showed signs of vigilance (e.g., internal debate to the point of factionalism). The results illustrate the usefulness of the GDQ for developing and empirically testing theory in organizational behavior from historical cases. Copyright 1998 Academic Press. PMID:9705805

  7. Reactive flow modeling of small scale detonation failure experiments for a baseline non-ideal explosive

    NASA Astrophysics Data System (ADS)

    Kittell, David E.; Cummock, Nick R.; Son, Steven F.

    2016-08-01

    Small scale characterization experiments using only 1-5 g of a baseline ammonium nitrate plus fuel oil (ANFO) explosive are discussed and simulated using an ignition and growth reactive flow model. There exists a strong need for the small scale characterization of non-ideal explosives in order to adequately survey the wide parameter space in sample composition, density, and microstructure of these materials. However, it is largely unknown in the scientific community whether any useful or meaningful result may be obtained from detonation failure, and whether a minimum sample size or level of confinement exists for the experiments. In this work, it is shown that the parameters of an ignition and growth rate law may be calibrated using the small scale data, which is obtained from a 35 GHz microwave interferometer. Calibration is feasible when the samples are heavily confined and overdriven; this conclusion is supported with detailed simulation output, including pressure and reaction contours inside the ANFO samples. The resulting shock wave velocity is most likely a combined chemical-mechanical response, and simulations of these experiments require an accurate unreacted equation of state (EOS) in addition to the calibrated reaction rate. Other experiments are proposed to gain further insight into the detonation failure data, as well as to help discriminate between the role of the EOS and reaction rate in predicting the measured outcome.

  8. Triggers for the Collapse of Ice Shelves in Antarctica: Investigating Compressive Arch Failure with Numerical Models

    NASA Astrophysics Data System (ADS)

    Huth, A.; Smith, B. E.

    2015-12-01

    Antarctic ice shelves restrain, or buttress, grounded ice from flowing freely into the ocean by redistributing the force of the ice flow to pinning points (ice rises) at the ice front and shear margins at adjacent bay walls. This buttressing process typically defines a 'compressive arch' in the strain rate-field of the ice shelf, where the smallest principal component transitions from compressive inland of the arch to extensive seaward of the arch. If the compressive arch is breached due to iceberg calving at the ice front or thinning at the shear margins, the ice shelf will retreat irreversibly to a new stable configuration or collapse entirely. This retreat can compromise ice shelf buttressing, resulting in sea-level rise and ocean freshening as grounded ice flows unrestricted into the ocean. Here, we investigate the dynamics of compressive arch failure using Larsen C ice shelf as a test case for a larger study that will include several other ice shelves and projections for sea-level rise. We use satellite observations to develop a steady state model of Larsen C in Elmer/ICE, a finite element ice sheet/ice flow software package. We run calving and thinning simulations to determine the conditions needed to trigger ice shelf retreat via compressive arch failure and discuss the likelihood of these scenarios occurring in relation to extrapolations of current melt profiles and calving trends.

  9. A new model of reaction-driven cracking: fluid volume consumption and tensile failure during serpentinization

    NASA Astrophysics Data System (ADS)

    Eichenbaum-Pikser, J. M.; Spiegelman, M. W.; Kelemen, P. B.; Wilson, C. R.

    2013-12-01

    Reactive fluid flow plays an important role in a wide range of geodynamic processes, such as melt migration, formation of hydrous minerals on fault surfaces, and chemical weathering. These processes are governed by the complex coupling between fluid transport, reaction, and solid deformation. Reaction-driven cracking is a potentially critical feedback mechanism, by which volume change associated with chemical reaction drives fracture in the surrounding rock. It has been proposed to play a role in both serpentinization and carbonation of peridotite, motivating consideration of its application to mineral carbon sequestration. Previous studies of reactive cracking have focused on the increase in solid volume, and as such, have considered failure in compression. However, if the consumption of fluid is considered in the overall volume budget, the reaction can be net volume reducing, potentially leading to failure in tension. To explore these problems, we have formulated and solved a 2-D model of coupled porous flow, reaction kinetics, and elastic deformation using the finite element model assembler TerraFERMA (Wilson et al, G3 2013 submitted). The model is applied to the serpentinization of peridotite, which can be reasonably approximated as the transfer of a single reactive component (H2O) between fluid and solid phases, making it a simple test case to explore the process. The behavior of the system is controlled by the competition between the rate of volume consumption by the reaction, and the rate of volume replacement by fluid transport, as characterized by a nondimensional parameter χ, which depends on permeability, reaction rate, and the bulk modulus of the solid. Large values of χ correspond to fast fluid transport relative to reaction rate, resulting in a low stress, volume replacing regime. At smaller values of χ, fluid transport cannot keep up with the reaction, resulting in pore fluid under-pressure and tensile solid stresses. For the range of χ relevant

  10. Preventive effect of American ginseng against premature ovarian failure in a rat model.

    PubMed

    Ge, Pengling; Xing, Nannan; Ren, Yanhai; Zhu, Lei; Han, Dongwei; Kuang, Haixue; Li, Ji

    2014-12-01

    Preclinical Research Premature ovarian failure (POF) is defined by the WHO as the loss of physiological ovarian function before the age of 40. The effect of American ginseng and its underlying mechanisms in preventing and treating premature ovarian failure (POF) was studied in female Sprague-Dawley rats where POF was induced by ip administration of 4-vinylcyclohexene diepoxide (VCD). Rat behavior, serum hormone levels, ovarian and uterine size, pathological features, and ovarian tissue expression of genes associated with POF were assessed in controls, untreated POF model rats, and POF model rats treated with low- (1.125 g/kg), medium- (2.25 g/kg), and high-dose (4.5 g/kg) American ginseng. Compared with untreated POF model rats, those treated with medium- and high-dose American ginseng had more stable behavior and better coat appearance as well as serum hormone levels closer to those in control rats. Moreover, treatment with medium- or high-dose American ginseng increased ovarian and uterine size. Hematoxylin and eosin-staining revealed mature follicles and endometrium with an alternating concave/convex surface structure with visible capillaries and glands in ginseng- treated POF rats. PLA2G4A expression was positively correlated with POF, while the expression levels of PAPPA, STC2, CCL2, and NELL1 were negatively correlated with POF. Our study showed that American ginseng may effectively prevent POF and alleviate POF symptoms by regulating serum hormone levels and altering the expression levels of genes related to POF in ovarian tissue. PMID:25424468

  11. Modeling Freedom From Progression for Standard-Risk Medulloblastoma: A Mathematical Tumor Control Model With Multiple Modes of Failure

    SciTech Connect

    Brodin, N. Patrik; Vogelius, Ivan R.; Björk-Eriksson, Thomas; Munck af Rosenschöld, Per; Bentzen, Søren M.

    2013-10-01

    Purpose: As pediatric medulloblastoma (MB) is a relatively rare disease, it is important to extract the maximum information from trials and cohort studies. Here, a framework was developed for modeling tumor control with multiple modes of failure and time-to-progression for standard-risk MB, using published pattern of failure data. Methods and Materials: Outcome data for standard-risk MB published after 1990 with pattern of relapse information were used to fit a tumor control dose-response model addressing failures in both the high-dose boost volume and the elective craniospinal volume. Estimates of 5-year event-free survival from 2 large randomized MB trials were used to model the time-to-progression distribution. Uncertainty in freedom from progression (FFP) was estimated by Monte Carlo sampling over the statistical uncertainty in input data. Results: The estimated 5-year FFP (95% confidence intervals [CI]) for craniospinal doses of 15, 18, 24, and 36 Gy while maintaining 54 Gy to the posterior fossa was 77% (95% CI, 70%-81%), 78% (95% CI, 73%-81%), 79% (95% CI, 76%-82%), and 80% (95% CI, 77%-84%) respectively. The uncertainty in FFP was considerably larger for craniospinal doses below 18 Gy, reflecting the lack of data in the lower dose range. Conclusions: Estimates of tumor control and time-to-progression for standard-risk MB provides a data-driven setting for hypothesis generation or power calculations for prospective trials, taking the uncertainties into account. The presented methods can also be applied to incorporate further risk-stratification for example based on molecular biomarkers, when the necessary data become available.

  12. Modeling the Influences of Electrostatic Discharge in Materials on a Failures of Onboard Electronic Equipment in under Microgcrogravity

    NASA Astrophysics Data System (ADS)

    Grichshenko, Valentina; Zhantayev, Zhumabek; Mukushev, Acemhan

    2016-07-01

    It is known, that during SV exploitation failures of automated systems happens as the result of complex influence of Space leading to SV's shorter life span, sometimes to their lose. All of the SV, functioning in the near-Earth Space (NES), subjected to influence of different Space factors. Causes and character of failure onboard equipment are different. Many researchers think that failures of onboard electronics connected to changing solar activity level. However, by the numerous onboard experiments established that even in the absence of solar burst in magnetostatic days there are registered failures of onboard electronics. In this paper discussed the results of modeling the impact of electrostatic discharge (ESD), occurring in the materials, on a failures of electronic onboard equipment in microgravity. The paper discusses the conditions of formation and influence of electrostatic discharge in microgravity on the elements of the onboard electronics in Space. Developed technique using circuit simulation in ISIS Proteus environment is discussed. Developed the recommendations for noise immunity of on-board equipment from ESD in Space. The results are used to predict the failure rate on-board electronics with the long term of space mission. Key words: microgravity, materials, failures, onboard electronics, Space

  13. Constraining Enceladus’s ice shell thickness using tidally driven Coulomb failure models of the tiger stripe fractures

    NASA Astrophysics Data System (ADS)

    Olgin, J. G.; Smith-Konter, B. R.; Pappalardo, R. T.

    2009-12-01

    The thickness of Enceladus’s ice shell, and subsequently the depth of its underlying ocean, plays an important role in determining the magnitude and orientation of tidal stresses on the surface of the satellite. The objective of this study is to attempt to constrain Enceladus’s ice shell thickness through assessment of tidally driven Coulomb failure of the tiger stripe fractures, probable sources of tectonic activity that reside along Enceladus’s south polar region. Using the SatStress computational model and assuming a global ocean and uniform ice shell thickness, we compare tidal stresses resulting from a suite of models of variable ice shell thickness (6 km, 24 km, 30 km, 40 km, 50 km, 75 km, and 90 km). Evaluation of the Love numbers for each model (l2, h2 and k2) suggest that ice shell thicknesses greater than a few 10s of km are not capable of generating stress conditions conducive to fault failure on Enceladus. We further investigate the feasibility of tiger stripe failure by applying a Coulomb failure model to the resulting tidal stresses. Based on previous work, we have shown that a 24 km thick ice shell model is capable of generating stress conditions that promote Coulomb failure and strike-slip displacements of ~0.4 m along some portions of the tiger stripe system, assuming a coefficient of friction of 0.2. We compare this reference model to the 6 km, 30 km, 40 km, 50 km, 75 km, and 90 km ice shell models and find that thin to moderate ice shell models do indeed support fault failure, while thick ice shell models do not. Models based on a 6 km ice shell thickness can yield strike-slip displacements on the order of 1 m along all segments of the tiger stripe system. Models based on a 30 km ice shell thickness can also generate strike-slip displacements (~0.1 m), however only on isolated fault segments. Finally, models based on a 40 km ice shell thickness or greater cannot generate stresses capable of Coulomb failure along any of the tiger stripe

  14. Metabolic effects of carbohydrate-copper interactions in swine

    SciTech Connect

    Scholfield, D.J.; Reiser, S.; Steele, N.; Darcey, S.; Richards, M.; Fields, M.; Smith, J.C.

    1986-03-01

    Inadequate dietary copper(Cu) is known to elicit several undesirable metabolic changes in humans and rats. Abnormal cardiac function, including sudden death is a common finding in copper deficient (CuD) rats, especially those fed diets with a high fructose (FR) content. Swine were chosen as the animal model for this project since their circulatory system is morphologically similar to that of humans. In an effort to further study these dietary effects 12 male and 12 female swine were randomly assigned to 4 groups of 6 pigs each and fed CuD and Cu supplemented (CuS) diets with 20% of calories from either FR or glucose (GL) for a period of 10 weeks. In agreement with data from recent experiments, CuD swine exhibited anemia, decreased ceruloplasmin, Cu-Zn superoxide dismutase and serum Cu; however, serum cholesterol and triglycerides decreased significantly when the animals were fed the CuD diets as compared to those fed CuS diets. Serum glutamic pyruvic transaminase (SGPT) activity was lowest for pigs fed the CuD FR diet compared to the CuS and CuD Gl groups during the study. SGPT activity usually increases when humans consume high FR diets. The results of these an