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  1. Experimental models of stress

    PubMed Central

    Patchev, Vladimir K.; Patchev, Alexandre V.

    2006-01-01

    Illustrating the complexity of the stress response and its multifaceted manifestations is the leading idea of this overview of experimental paradigms used for stress induction in laboratory animals. The description of key features of models based on naturalistic stressors, pharmacological challenges, and genomic manipulations is complemented by comprehensive analysis of physiological, behavioral, neurochemical, and endocrine changes and their appropriatness as outcome readouts. Particular attention has been paid to the role of sex and age as determinants of the dynamics of the stress response. Possible translational applications of stress-inducing paradigms as models of disease are briefly sketched. PMID:17290800

  2. Experimental Models of Pancreatitis

    PubMed Central

    Hyun, Jong Jin

    2014-01-01

    Acute pancreatitis is an inflammatory disease characterized by interstitial edema, inflammatory cell infiltration, and acinar cell necrosis, depending on its severity. Regardless of the extent of tissue injury, acute pancreatitis is a completely reversible process with evident normal tissue architecture after recovery. Its pathogenic mechanism has been known to be closely related to intracellular digestive enzyme activation. In contrast to acute pancreatitis, chronic pancreatitis is characterized by irreversible tissue damage such as acinar cell atrophy and pancreatic fibrosis that results in exocrine and endocrine insufficiency. Recently, many studies of chronic pancreatitis have been prompted by the discovery of the pancreatic stellate cell, which has been identified and distinguished as the key effector cell of pancreatic fibrosis. However, investigations into the pathogenesis and treatment of pancreatitis face many obstacles because of its anatomical location and disparate clinical course. Due to these difficulties, most of our knowledge on pancreatitis is based on research conducted using experimental models of pancreatitis. In this review, several experimental models of pancreatitis will be discussed in terms of technique, advantages, and limitations. PMID:24944983

  3. Experimental models of uveal melanoma.

    PubMed

    Blanco, Paula L; Caissie, Amanda L; Burnier, Miguel N

    2004-06-01

    Over the past several decades, considerable effort has been directed toward developing suitable experimental models for the study of uveal melanoma. Animal models of uveal melanoma have undergone many improvements, leading to the development of experimental systems that better represent the disease in human beings. A major advance has come from the use of human uveal melanoma cell lines capable of inducing tumour growth and metastatic disease in immunodeficient hosts. Knowledge gained from the use of experimental models will ultimately be translated into better diagnostic and therapeutic strategies for patients with uveal melanoma. In this review the authors describe the current state-of-the-art designs of experimental models of uveal melanoma, highlighting the advantages and disadvantages of the available models. Novel findings from a rabbit model of uveal melanoma are also presented.

  4. Experimental Building Information Models

    DTIC Science & Technology

    2011-09-01

    link can later be removed. In some cases, it may also help to have a 2D drawing extracted from the 3D model, such as when laying out a large floor...plan. In such cases, a Revit plan view can be exported as a 2D Autocad DWG file using Revit’s export function. This 2D DWG file can then be...with government-furnished 2D Autocad DWG files. The 2D DWG files included architectural, mechanical, plumbing, and electrical layouts, and were

  5. [Experimental models of acute pancreatitis].

    PubMed

    Ceranowicz, Piotr; Cieszkowski, Jakub; Warzecha, Zygmunt; Dembiński, Artur

    2015-02-21

    Acute pancreatitis is a severe disease with high mortality. Clinical studies can bring some data about etiology, pathogenesis and the course of acute pancreatitis. However, studies concerning early events of this disease and the new concepts of treatment cannot be performed on humans, due to ethical reasons. Animal models of acute pancreatitis have been developed to solve this problem. This review presents currently used experimental models of acute pancreatitis, their properties and clinical relevance. Experimental models of acute pancreatitis can be divided into in vivo (non-invasive and invasive) and ex vivo models. The onset, development, severity and extent of acute pancreatitis, as well as the mortality, vary considerably between these different models. Animal models reproducibly produce mild, moderate or severe acute pancreatitis. One of the most commonly used models of acute pancreatitis is created by administration of supramaximal doses of cerulein, an analog of cholecystokinin. This model produces acute mild edematous pancreatitis in rats, whereas administration of cerulein in mice leads to the development of acute necrotizing pancreatitis. Acute pancreatitis evoked by retrograde administration of sodium taurocholate into the pancreatic duct is the most often used model of acute severe necrotizing pancreatitis in rats. Ex vivo models allow to eliminate the influence of hormonal and nervous factors on the development of acute pancreatitis.

  6. [Experimental models of Huntington's disease].

    PubMed

    García-Ramos, R; del Val-Fernández, J; Catalán-Alonso, M J; Barcia-Albacar, J A; Matías-Guiu, J

    Huntington's disease (HD) is an autosomal dominant hereditary disease caused by triplet repetition in exon 1 of the huntingtin protein located in chromosome 4. Medium spiny neurons in the striatum are selectively affected. Clinical manifestations include progressive behavioural, motor and cognitive disorders. There is no treatment available today capable of modifying the natural course of the disease. A great amount of research work is being carried out, much of which involves animal models of the disease. We reviewed the articles published in PubMed on basic research into HD and analysed the most frequently used models. Transgenic mouse models, excitotoxic models, transgenic fly models and cell cultures are all used in studies into HD. The advantages and disadvantages of each of them are highlighted. The contribution made by each model of HD must be known in order to draw up a correct design in experimental studies of the disease.

  7. Experimental models of hepatocellular carcinoma☆

    PubMed Central

    Newell, Philippa; Villanueva, Augusto; Friedman, Scott L.; Koike, Kazuhiko; Llovet, Josep M.

    2010-01-01

    Hepatocellular carcinoma (HCC) is a common and deadly cancer whose pathogenesis is incompletely understood. Comparative genomic studies from human HCC samples have classified HCCs into different molecular subgroups; yet, the unifying feature of this tumor is its propensity to arise upon a background of inflammation and fibrosis. This review seeks to analyze the available experimental models in HCC research and to correlate data from human populations with them in order to consolidate our efforts to date, as it is increasingly clear that different models will be required to mimic different subclasses of the neoplasm. These models will be instrumental in the evaluation of compounds targeting specific molecular pathways in future preclinical studies. PMID:18314222

  8. Epithelial Ovarian Cancer Experimental Models

    PubMed Central

    Lengyel, E; Burdette, JE; Kenny, HA; Matei, D; Pilrose, J; Haluska, P.; Nephew, KP; Hales, DB; Stack, MS

    2014-01-01

    Epithelial ovarian cancer (OvCa) is associated with high mortality and, as the majority (>75%) of women with OvCa have metastatic disease at the time of diagnosis, rates of survival have not changed appreciably over 30 years. A mechanistic understanding of OvCa initiation and progression is hindered by the complexity of genetic and/or environmental initiating events and lack of clarity regarding the cell(s) or tissue(s) of origin. Metastasis of OvCa involves direct extension or exfoliation of cells and cellular aggregates into the peritoneal cavity, survival of matrix-detached cells in a complex ascites fluid phase, and subsequent adhesion to the mesothelium lining covering abdominal organs to establish secondary lesions containing host stromal and inflammatory components. Development of experimental models to recapitulate this unique mechanism of metastasis presents a remarkable scientific challenge and many approaches used to study other solid tumors (lung, colon, and breast, for example) are not transferable to OvCa research given the distinct metastasis pattern and unique tumor microenvironment. This review will discuss recent progress in the development and refinement of experimental models to study OvCa. Novel cellular, three-dimensional organotypic, and ex vivo models are considered and the current in vivo models summarized. The review critically evaluates currently available genetic mouse models of OvCa, the emergence of xenopatients, and the utility of the hen model to study OvCa prevention, tumorigenesis, metastasis, and chemoresistance. As these new approaches more accurately recapitulate the complex tumor microenvironment, it is predicted that new opportunities for enhanced understanding of disease progression, metastasis and therapeutic response will emerge. PMID:23934194

  9. Experimental models of developmental hypothyroidism.

    PubMed

    Argumedo, G S; Sanz, C R; Olguín, H J

    2012-02-01

    Hypothyroidism is a systemic disease resulting from either thyroid gland's anatomical and functional absence or lack of hypophyseal stimulation, both of which can lead to deficiency in thyroid hormone (TH) production. TH is essential for human and animal development, growth, and function of multiple organs. Children with deficient TH can develop alterations in central nervous system (CNS), striated muscle, bone tissue, liver, bone marrow, and cardiorespiratory system. Among the clinical outlook are signs like breathing difficulty, cardiac insufficiency, dysphagia, and repeated bronchial aspiration, constipation, muscle weakness, cognitive alterations, cochlear dysfunction, reduced height, defects in temperature regulation, anaemia, jaundice, susceptibility to infection, and others. Experimental and clinical studies have shown that TH is very essential for normal brain development. Other research work based on mice pointed out that a reduced level of TH in pregnant mother leads to congenital hypothyroidism in animal models and it is associated with mental retardation, deep neurologic deficiency that impacts on cognitive, learning, and memory functions. The principal experimental model studies that have focused on hypothyroidism are reviewed in this study. This is important on considering the fact that almost all animal species require thyroid hormones for their metabolism.

  10. Experimental animal models of osteonecrosis.

    PubMed

    Fan, Meng; Peng, Jiang; Qin, Ling; Lu, Shibi

    2011-08-01

    Osteonecrosis (ON) or avascular necrosis (AVN) is a common bone metabolic disorder, mostly affecting femoral head. Although many biological, biophysical, and surgical methods have been tested to preserve the femoral head with ON, none has been proven fully satisfactory. It lacks consensus on an optimal approach for treatment. This is due, at least in part, to the lack of ability to systematically compare treatment efficacy using an ideal animal model that mimics full-range osteonecrosis of femoral head (ONFH) in humans with high incidence of joint collapse accompanied by reparative reaction adjacent to the necrotic bone in a reproducible and accessible way. A number of preclinical animal ON models have been established for testing potential efficacy of various modalities developed for prevention and treatment of ON before introduction into clinics for potential applications. This paper describes a number of different methods for creating animal experimental ON models. Advantages and disadvantages of such models are also discussed as reference for future research in battle against this important medical condition.

  11. Experimental models of liver fibrosis.

    PubMed

    Crespo Yanguas, Sara; Cogliati, Bruno; Willebrords, Joost; Maes, Michaël; Colle, Isabelle; van den Bossche, Bert; de Oliveira, Claudia Pinto Marques Souza; Andraus, Wellington; Alves, Venâncio Avancini; Leclercq, Isabelle; Vinken, Mathieu

    2016-05-01

    Hepatic fibrosis is a wound healing response to insults and as such affects the entire world population. In industrialized countries, the main causes of liver fibrosis include alcohol abuse, chronic hepatitis virus infection and non-alcoholic steatohepatitis. A central event in liver fibrosis is the activation of hepatic stellate cells, which is triggered by a plethora of signaling pathways. Liver fibrosis can progress into more severe stages, known as cirrhosis, when liver acini are substituted by nodules, and further to hepatocellular carcinoma. Considerable efforts are currently devoted to liver fibrosis research, not only with the goal of further elucidating the molecular mechanisms that drive this disease, but equally in view of establishing effective diagnostic and therapeutic strategies. The present paper provides a state-of-the-art overview of in vivo and in vitro models used in the field of experimental liver fibrosis research.

  12. New model systems for experimental evolution.

    PubMed

    Collins, Sinéad

    2013-07-01

    Microbial experimental evolution uses a few well-characterized model systems to answer fundamental questions about how evolution works. This special section highlights novel model systems for experimental evolution, with a focus on marine model systems that can be used to understand evolutionary responses to global change in the oceans.

  13. Experimental Models of Membranous Nephropathy

    PubMed Central

    Jefferson, J. Ashley; Pippin, Jeffrey W.; Shankland, Stuart J.

    2011-01-01

    Membranous nephropathy (MN) is one of the commonest glomerular diseases, typically presenting in older males with nephrotic syndrome. The development and characterization of animal models of MN, in particular, the passive Heymann nephritis model (PHN), has greatly advanced our understanding of this disease. In this review we discuss the different animal models of human MN that are available, with an emphasis on the PHN model, including technical issues, the typical disease course and its application to human disease. PMID:21359154

  14. Experimental mammary carcinogenesis - Rat models.

    PubMed

    Alvarado, Antonieta; Faustino-Rocha, Ana I; Colaço, Bruno; Oliveira, Paula A

    2017-03-15

    Mammary cancer is one of the most common cancers, victimizing more than half a million of women worldwide every year. Despite all the studies in this field, the current therapeutic approaches are not effective and have several devastating effects for patients. In this way, the need to better understand the mammary cancer biopathology and find effective therapies led to the development of several rodent models over years. With this review, the authors intended to provide the readers with an overview of the rat models used to study mammary carcinogenesis, with a special emphasis on chemically-induced models.

  15. Experimental models of anxiety. Problems and perspectives.

    PubMed

    Griez, E

    1984-01-01

    In a brief review of the field of experimental psychopathology, the author observes that few adequate laboratory models of anxiety have been produced. Criteria to set up valid anxiety models are discussed. The carbon dioxide inhalation technique, an anxiomimetic intervention, is then proposed as a new human panic attack model and compared to the existing lactate infusion method. Both appear as promising agents in the experimental study of panic anxiety.

  16. [An experimental model of suppurative osteomyelitis].

    PubMed

    Privalov, V A; Svetlakov, A L; Kushakovskiĭ, O S; Ebert, L Ia; Giniatullin, R U; Svetlakova, I A; Iarovoĭ, N N

    2000-01-01

    A new experimental rabbit model of acute purulent osteomyelitis is proposed. The model is reproduced by percutaneous introduction of 4 million St. aureus microorganisms into the medullary channel of the femoral bone after aseptic destruction of the bone marrow by ethyl alcohol and hot saline. The model satisfies the demands of good reproduction, reduces probability of contamination of periosteal tissues during intraosteal inoculation and provides reproduction of local inflammation without its generalization which results in reduced number of fatal outcomes among experimental animals.

  17. Model refinement for offshore platforms: Experimental study

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Chen, Zongli; Wu, Yanjian

    2017-08-01

    Offshore jacket platforms are widely used in offshore oil and gas exploitation. Finite element models of such structures need to have many degrees of freedom (DOFs) to represent the geometrical detail of complex structures, thereby leading to incompatibility in the number of DOFs of experimental models. To bring them both to the same order while ensuring that the essential eigen- properties of the refined model match those of experimental models, an extended model refinement procedure is presented in this paper. Vibration testing of an offshore jacket platform model is performed to validate the applicability of the proposed approach. A full-order finite element model of the platform is established and then tuned to meet the measured modal properties identified from the acceleration signals. Both model reduction and modal expansion methods are investigated, as well as various scenarios of sensor arrangements. Upon completion of the refinement, the updated jacket platform model matches the natural frequencies of the measured model well.

  18. Experimental models of demyelination and remyelination.

    PubMed

    Torre-Fuentes, L; Moreno-Jiménez, L; Pytel, V; Matías-Guiu, J A; Gómez-Pinedo, U; Matías-Guiu, J

    2017-08-29

    Experimental animal models constitute a useful tool to deepen our knowledge of central nervous system disorders. In the case of multiple sclerosis, however, there is no such specific model able to provide an overview of the disease; multiple models covering the different pathophysiological features of the disease are therefore necessary. We reviewed the different in vitro and in vivo experimental models used in multiple sclerosis research. Concerning in vitro models, we analysed cell cultures and slice models. As for in vivo models, we examined such models of autoimmunity and inflammation as experimental allergic encephalitis in different animals and virus-induced demyelinating diseases. Furthermore, we analysed models of demyelination and remyelination, including chemical lesions caused by cuprizone, lysolecithin, and ethidium bromide; zebrafish; and transgenic models. Experimental models provide a deeper understanding of the different pathogenic mechanisms involved in multiple sclerosis. Choosing one model or another depends on the specific aims of the study. Copyright © 2017 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

  19. Improving the physiological realism of experimental models.

    PubMed

    Vinnakota, Kalyan C; Cha, Chae Y; Rorsman, Patrik; Balaban, Robert S; La Gerche, Andre; Wade-Martins, Richard; Beard, Daniel A; Jeneson, Jeroen A L

    2016-04-06

    The Virtual Physiological Human (VPH) project aims to develop integrative, explanatory and predictive computational models (C-Models) as numerical investigational tools to study disease, identify and design effective therapies and provide an in silico platform for drug screening. Ultimately, these models rely on the analysis and integration of experimental data. As such, the success of VPH depends on the availability of physiologically realistic experimental models (E-Models) of human organ function that can be parametrized to test the numerical models. Here, the current state of suitable E-models, ranging from in vitro non-human cell organelles to in vivo human organ systems, is discussed. Specifically, challenges and recent progress in improving the physiological realism of E-models that may benefit the VPH project are highlighted and discussed using examples from the field of research on cardiovascular disease, musculoskeletal disorders, diabetes and Parkinson's disease.

  20. Improving the physiological realism of experimental models

    PubMed Central

    Vinnakota, Kalyan C.; Cha, Chae Y.; Rorsman, Patrik; Balaban, Robert S.; La Gerche, Andre; Wade-Martins, Richard; Beard, Daniel A.

    2016-01-01

    The Virtual Physiological Human (VPH) project aims to develop integrative, explanatory and predictive computational models (C-Models) as numerical investigational tools to study disease, identify and design effective therapies and provide an in silico platform for drug screening. Ultimately, these models rely on the analysis and integration of experimental data. As such, the success of VPH depends on the availability of physiologically realistic experimental models (E-Models) of human organ function that can be parametrized to test the numerical models. Here, the current state of suitable E-models, ranging from in vitro non-human cell organelles to in vivo human organ systems, is discussed. Specifically, challenges and recent progress in improving the physiological realism of E-models that may benefit the VPH project are highlighted and discussed using examples from the field of research on cardiovascular disease, musculoskeletal disorders, diabetes and Parkinson's disease. PMID:27051507

  1. In vivo experimental models of epilepsy.

    PubMed

    Rubio, Carmen; Rubio-Osornio, Moises; Retana-Márquez, Socorro; Verónica Custodio, Marisol López; Paz, Carlos

    2010-12-01

    This study reviews the different in vivo experimental models that have been used for the study of epileptogenesis. In this review we will focus on how to replicate the different models that have led to the study of partial seizures, as well as generalized seizures and the status epilepticus. The main characteristics that participate in the processes that generate and modulate the manifestations of different models of epileptogenesis are described. The development of several models of experimental epilepsy in animals has clearly helped the study of specific brain areas capable of causing convulsions. The experimental models of epilepsy also have helped in the study the mechanisms and actions of epilepsy drugs. In order to develop experimental animal models of epilepsy, animals are generally chosen according to the kind of epilepsy that can be developed and studied. It is currently known that animal species can have epileptic seizures similar to those in humans. However, it is important to keep in mind that it has not been possible to entirely evaluate all manifestations of human epilepsy. Notwithstanding, these experimental models of epilepsy have allowed a partial understanding of most of the underlying mechanisms of this disease.

  2. Experimental falsification of Leggett's nonlocal variable model.

    PubMed

    Branciard, Cyril; Ling, Alexander; Gisin, Nicolas; Kurtsiefer, Christian; Lamas-Linares, Antia; Scarani, Valerio

    2007-11-23

    Bell's theorem guarantees that no model based on local variables can reproduce quantum correlations. Also, some models based on nonlocal variables, if subject to apparently "reasonable" constraints, may fail to reproduce quantum physics. In this Letter, we introduce a family of inequalities, which use a finite number of measurement settings, and which therefore allow testing Leggett's nonlocal model versus quantum physics. Our experimental data falsify Leggett's model and are in agreement with quantum predictions.

  3. Understanding Leadership: An Experimental-Experiential Model

    ERIC Educational Resources Information Center

    Hole, George T.

    2014-01-01

    Books about leadership are dangerous to readers who fantasize about being leaders or apply leadership ideas as if they were proven formulas. As an antidote, I offer an experimental framework in which any leadership-management model can be tested to gain experiential understanding of the model. As a result one can gain reality-based insights about…

  4. Comparing fluid mechanics models with experimental data.

    PubMed Central

    Spedding, G R

    2003-01-01

    The art of modelling the physical world lies in the appropriate simplification and abstraction of the complete problem. In fluid mechanics, the Navier-Stokes equations provide a model that is valid under most circumstances germane to animal locomotion, but the complexity of solutions provides strong incentive for the development of further, more simplified practical models. When the flow organizes itself so that all shearing motions are collected into localized patches, then various mathematical vortex models have been very successful in predicting and furthering the physical understanding of many flows, particularly in aerodynamics. Experimental models have the significant added convenience that the fluid mechanics can be generated by a real fluid, not a model, provided the appropriate dimensionless groups have similar values. Then, analogous problems can be encountered in making intelligible but independent descriptions of the experimental results. Finally, model predictions and experimental results may be compared if, and only if, numerical estimates of the likely variations in the tested quantities are provided. Examples from recent experimental measurements of wakes behind a fixed wing and behind a bird in free flight are used to illustrate these principles. PMID:14561348

  5. Rodent Models of Experimental Autoimmune Uveitis

    PubMed Central

    Agarwal, Rajeev K.; Silver, Phyllis B.; Caspi, Rachel R.

    2013-01-01

    The model of experimental autoimmune uveitis (EAU) in mice and in rats is described. EAU targets immunologically privileged retinal antigens and serves as a model of autoimmune uveitis in humans as well as a model for autoimmunity in a more general sense. EAU is a well-characterized, robust, and reproducible model that is easily followed and quantitated. It is inducible with synthetic peptides derived from retinal autoantigens in commonly available strains of rats and mice. The ability to induce EAU in various gene-manipulated, including HLA-transgenic, mouse strains makes the EAU model suitable for the study of basic mechanisms as well as in clinically relevant interventions. PMID:22933083

  6. Experimental and Modeling Studies of Massif Anorthosites

    NASA Technical Reports Server (NTRS)

    Longhi, John

    1999-01-01

    This termination report covers the latter part of a single research effort spanning several grant cycles. During this time there was a single title, "Experimental and Modeling Studies of Massif Anorthosites", but there were several contract numbers as the mode and location of NASA contract administration changed. Initially, the project was funded as an increment to the PI's other grant, "Early Differentiation of the Moon: Experimental and Modeling Studies", but subsequently it became an independent grant. Table 1 contains a brief summary of the dates and contract numbers.

  7. Experimental Concepts for Testing Seismic Hazard Models

    NASA Astrophysics Data System (ADS)

    Marzocchi, W.; Jordan, T. H.

    2015-12-01

    Seismic hazard analysis is the primary interface through which useful information about earthquake rupture and wave propagation is delivered to society. To account for the randomness (aleatory variability) and limited knowledge (epistemic uncertainty) of these natural processes, seismologists must formulate and test hazard models using the concepts of probability. In this presentation, we will address the scientific objections that have been raised over the years against probabilistic seismic hazard analysis (PSHA). Owing to the paucity of observations, we must rely on expert opinion to quantify the epistemic uncertainties of PSHA models (e.g., in the weighting of individual models from logic-tree ensembles of plausible models). The main theoretical issue is a frequentist critique: subjectivity is immeasurable; ergo, PSHA models cannot be objectively tested against data; ergo, they are fundamentally unscientific. We have argued (PNAS, 111, 11973-11978) that the Bayesian subjectivity required for casting epistemic uncertainties can be bridged with the frequentist objectivity needed for pure significance testing through "experimental concepts." An experimental concept specifies collections of data, observed and not yet observed, that are judged to be exchangeable (i.e., with a joint distribution independent of the data ordering) when conditioned on a set of explanatory variables. We illustrate, through concrete examples, experimental concepts useful in the testing of PSHA models for ontological errors in the presence of aleatory variability and epistemic uncertainty. In particular, we describe experimental concepts that lead to exchangeable binary sequences that are statistically independent but not identically distributed, showing how the Bayesian concept of exchangeability generalizes the frequentist concept of experimental repeatability. We also address the issue of testing PSHA models using spatially correlated data.

  8. Optimal Experimental Design for Model Discrimination

    PubMed Central

    Myung, Jay I.; Pitt, Mark A.

    2009-01-01

    Models of a psychological process can be difficult to discriminate experimentally because it is not easy to determine the values of the critical design variables (e.g., presentation schedule, stimulus structure) that will be most informative in differentiating them. Recent developments in sampling-based search methods in statistics make it possible to determine these values, and thereby identify an optimal experimental design. After describing the method, it is demonstrated in two content areas in cognitive psychology in which models are highly competitive: retention (i.e., forgetting) and categorization. The optimal design is compared with the quality of designs used in the literature. The findings demonstrate that design optimization has the potential to increase the informativeness of the experimental method. PMID:19618983

  9. [Experimental models of human skin aging].

    PubMed

    Nikolakis, G; Zoschke, C; Makrantonaki, E; Hausmann, C; Schäfer-Korting, M; Zouboulis, C C

    2016-02-01

    The skin is a representative model for the study of human aging. Despite the high regenerative capacity of the skin, skin physiology changes over the course of life. Medical and cosmetic research is trying to prevent aging, to slow, to stop, or to reverse it. Effects of age-related DNA damage and of changing skin structure on pharmacological parameters are largely unknown. This review article summarizes the state of scientific knowledge in the field of experimental models of human skin aging and shows approaches to improve organotypic skin models, to develop predictive models of aging, and improve aging research.

  10. Optimal Experimental Design for Model Discrimination

    ERIC Educational Resources Information Center

    Myung, Jay I.; Pitt, Mark A.

    2009-01-01

    Models of a psychological process can be difficult to discriminate experimentally because it is not easy to determine the values of the critical design variables (e.g., presentation schedule, stimulus structure) that will be most informative in differentiating them. Recent developments in sampling-based search methods in statistics make it…

  11. Cholestasis: human disease and experimental animal models.

    PubMed

    Rodríguez-Garay, Emilio Alberto

    2003-01-01

    Cholestasis may result from a failure in bile secretion in hepatocytes or ductular cells, or from a blockade to the free bile flow. Human cholestasis may be induced by many drugs, being antibiotics the more common. Other types of cholestasis seen in humans are a group of familial cholestatic disorders, obstructive cholestasis, primary biliary cirrhosis, extrahepatic biliary atresia, primary sclerosing cholangitis, cholestasis of pregnancy, oral contraceptive-induced cholestasis, and sepsis-induced cholestasis. Experimental animal models allow the understanding of pathophysiological mechanisms involved and their clinical correlates. The most common experimental models of intrahepatic cholestasis are estrogen-induced, endotoxin-induced and drug-induced cholestasis. A well known model of extrahepatic biliary obstruction is common bile duct ligation. Drug-induced cholestasis were described using different drugs. On this regard, alpha naphthylisothiocyanate treatment has been extensively used, permitting to describe not only cholestatic alterations but also compensatory mechanisms. Congenital defficiency of transport proteins also were studied in natural rat models of cholestasis. The experimental animal models allow to define down-regulated alterations of hepatocyte transport proteins, and up-regulated ones acting as compensatory mechanisms. In conclusion, animal model and transport protein studies are necessary for the progressive understanding of congenital and acquired human cholestasis, and regulatory mechanisms that operate on liver cells.

  12. Integrated pollutant removal: modeling and experimentation

    SciTech Connect

    Ochs, Thomas L.; Oryshchyn, Danylo B.; Summers, Cathy A.

    2005-01-01

    Experimental and computational work at the Albany Research Center, USDOE is investigating an integrated pollutant removal (IPR) process which removes all pollutants from flue gas, including SOX, NOX, particulates, CO2, and Hg. In combination with flue gas recirculation, heat recovery, and oxy-fuel combustion, the process produces solid, gas, and liquid waste streams. The gas exhaust stream comprises O2 and N2. Liquid streams contain H2O, SOX, NOX, and CO2. Computer modeling and low to moderate pressure experimentation are defining system chemistry with respect to SOX and H2O as well as heat and mass transfer for the IPR process.

  13. Irradiation Design for an Experimental Murine Model

    SciTech Connect

    Ballesteros-Zebadua, P.; Moreno-Jimenez, S.; Suarez-Campos, J. E.; Celis, M. A.; Larraga-Gutierrez, J. M.; Garcia-Garduno, O. A.; Rubio-Osornio, M. C.; Custodio-Ramirez, V.; Paz, C.

    2010-12-07

    In radiotherapy and stereotactic radiosurgery, small animal experimental models are frequently used, since there are still a lot of unsolved questions about the biological and biochemical effects of ionizing radiation. This work presents a method for small-animal brain radiotherapy compatible with a dedicated 6MV Linac. This rodent model is focused on the research of the inflammatory effects produced by ionizing radiation in the brain. In this work comparisons between Pencil Beam and Monte Carlo techniques, were used in order to evaluate accuracy of the calculated dose using a commercial planning system. Challenges in this murine model are discussed.

  14. Irradiation Design for an Experimental Murine Model

    NASA Astrophysics Data System (ADS)

    Ballesteros-Zebadúa, P.; Lárraga-Gutierrez, J. M.; García-Garduño, O. A.; Rubio-Osornio, M. C.; Custodio-Ramírez, V.; Moreno-Jimenez, S.; Suarez-Campos, J. E.; Paz, C.; Celis, M. A.

    2010-12-01

    In radiotherapy and stereotactic radiosurgery, small animal experimental models are frequently used, since there are still a lot of unsolved questions about the biological and biochemical effects of ionizing radiation. This work presents a method for small-animal brain radiotherapy compatible with a dedicated 6MV Linac. This rodent model is focused on the research of the inflammatory effects produced by ionizing radiation in the brain. In this work comparisons between Pencil Beam and Monte Carlo techniques, were used in order to evaluate accuracy of the calculated dose using a commercial planning system. Challenges in this murine model are discussed.

  15. Experimental "evolutional machines": mathematical and experimental modeling of biological evolution

    NASA Astrophysics Data System (ADS)

    Brilkov, A. V.; Loginov, I. A.; Morozova, E. V.; Shuvaev, A. N.; Pechurkin, N. S.

    Experimentalists possess model systems of two major types for study of evolution continuous cultivation in the chemostat and long-term development in closed laboratory microecosystems with several trophic structure If evolutionary changes or transfer from one steady state to another in the result of changing qualitative properties of the system take place in such systems the main characteristics of these evolution steps can be measured By now this has not been realized from the point of view of methodology though a lot of data on the work of both types of evolutionary machines has been collected In our experiments with long-term continuous cultivation we used the bacterial strains containing in plasmids the cloned genes of bioluminescence and green fluorescent protein which expression level can be easily changed and controlled In spite of the apparent kinetic diversity of evolutionary transfers in two types of systems the general mechanisms characterizing the increase of used energy flow by populations of primer producent can be revealed at their study According to the energy approach at spontaneous transfer from one steady state to another e g in the process of microevolution competition or selection heat dissipation characterizing the rate of entropy growth should increase rather then decrease or maintain steady as usually believed The results of our observations of experimental evolution require further development of thermodynamic theory of open and closed biological systems and further study of general mechanisms of biological

  16. Experimental animal models in periodontology: a review.

    PubMed

    Struillou, Xavier; Boutigny, Hervé; Soueidan, Assem; Layrolle, Pierre

    2010-04-29

    In periodontal research, animal studies are complementary to in vitro experiments prior to testing new treatments. Animal models should make possible the validation of hypotheses and prove the safety and efficacy of new regenerating approaches using biomaterials, growth factors or stem cells. A review of the literature was carried out by using electronic databases (PubMed, ISI Web of Science). Numerous animal models in different species such as rats, hamsters, rabbits, ferrets, canines and primates have been used for modeling human periodontal diseases and treatments. However, both the anatomy and physiopathology of animals are different from those of humans, making difficult the evaluation of new therapies. Experimental models have been developed in order to reproduce major periodontal diseases (gingivitis, periodontitis), their pathogenesis and to investigate new surgical techniques. The aim of this review is to define the most pertinent animal models for periodontal research depending on the hypothesis and expected results.

  17. Experimental models of melatonin-deficient hypertension.

    PubMed

    Simko, Fedor; Reiter, Russel J; Pechanova, Olga; Paulis, Ludovit

    2013-01-01

    Melatonin secreted by the pineal gland plays an important role in the regulation of blood pressure (BP) and its administration reduces hypertension both in animals and humans. There are two experimental models of melatonin-deficient hypertension: one induced by pinealectomy and another by continuous 24 hour exposure to light. Both models cause melatonin deficiency and prevent darkness-mediated nocturnal melatonin secretion and are associated with increased BP and myocardial, vascular and renal dysfunction. These models also lead to neurohumoral activation of the renin-angiotensin system, sympathetic nervous system, adrenocorticotrophin-glucocorticoid axis and cause insulin resistance. Together, these alterations contribute to rise in blood pressure by vasoconstrictive or circulatory fluid volume overload. The light induced hypertension model mimics the melatonin deficiency in patients with insufficient nocturnal BP decline, in those who have night shift or who are exposed to environmental light pollution. For this reason, this model is useful in development of anti-hypertensive drugs.

  18. Extracting model equations from experimental data

    NASA Astrophysics Data System (ADS)

    Friedrich, R.; Siegert, S.; Peinke, J.; Lück, St.; Siefert, M.; Lindemann, M.; Raethjen, J.; Deuschl, G.; Pfister, G.

    2000-06-01

    This letter wants to present a general data-driven method for formulating suitable model equations for nonlinear complex systems. The method is validated in a quantitative way by its application to experimentally found data of a chaotic electric circuit. Furthermore, the results of an analysis of tremor data from patients suffering from Parkinson's disease, from essential tremor, and from normal subjects with physiological tremor are presented, discussed and compared. They allow a distinction between the different forms of tremor.

  19. Assessment of four experimental models of hyperlipidemia.

    PubMed

    Madariaga, Yisel González; Cárdenas, María Boffill; Irsula, Maibia Tamayo; Alfonso, Orestes Castillo; Cáceres, Bennia Alfonso; Morgado, Emoe Betancourt

    2015-04-01

    Various animal models of hyperlipidemia are used in research. Four rodent hyperlipidemia experimental models are examined in this study: three chronic hyperlipidemia models based on dietary supplementation with lipid or sucrose for 3 months and one acute hyperlipidemia model based on administration of the nonionic surfactant poloxamer. Neither lipid supplementation nor sucrose supplementation in Wistar rats was effective for establishing hyperlipidemia. Combining both lipid and sucrose supplementation in BALB/c mice induced hypercholesterolemia, as reflected in a considerable increase in blood cholesterol concentration, but did not produce an increase in blood triglyceride concentration. Poloxamer administration in C57BL/J6 mice produced increases in blood cholesterol and triglyceride concentrations. The authors conclude that supplementation of both lipid and sucrose in BALB/c mice was the most effective method for developing chronic hypercholesterolemia.

  20. Experimental animal modelling for TB vaccine development.

    PubMed

    Cardona, Pere-Joan; Williams, Ann

    2017-03-01

    Research for a novel vaccine to prevent tuberculosis is an urgent medical need. The current vaccine, BCG, has demonstrated a non-homogenous efficacy in humans, but still is the gold standard to be improved upon. In general, the main indicator for testing the potency of new candidates in animal models is the reduction of the bacillary load in the lungs at the acute phase of the infection. Usually, this reduction is similar to that induced by BCG, although in some cases a weak but significant improvement can be detected, but none of candidates are able to prevent establishment of infection. The main characteristics of several laboratory animals are reviewed, reflecting that none are able to simulate the whole characteristics of human tuberculosis. As, so far, no surrogate of protection has been found, it is important to test new candidates in several models in order to generate convincing evidence of efficacy that might be better than that of BCG in humans. It is also important to investigate the use of "in silico" and "ex vivo" models to better understand experimental data and also to try to replace, or at least reduce and refine experimental models in animals. Copyright © 2017. Published by Elsevier Ltd.

  1. Modelling an experimental methane fuel processor

    NASA Astrophysics Data System (ADS)

    Lin, Shi-Tin; Chen, Yih-Hang; Yu, Cheng-Ching; Liu, Yen-Chun; Lee, Chiou-Hwang

    Steady-state models are developed to describe an experimental methane fuel processor that is intended to provide hydrogen for a fuel cell system for power generation (2-3 kW). First-principle reactor models are constructed to describe a series of reactions, i.e., steam and autothermal reforming (SR/ATR), high- and low-temperature water-gas shift (HTS/LTS) reactions and preferential oxidation (PROX) reactions, at different sectors of the reactor system for methane reforming as well as gas cleaning. The pre-exponential factors of the rate constants are adjusted to fit the experimental data and the resultant reactor model provides a reasonably good description of steady-state behaviour. Next, sensitivity analyses are performed to locate the optimum operating point of the fuel processor. The objective function of the optimization is fuel processor efficiency. The dominating optimization variables include: the ratios of water and oxygen to the hydrocarbon feed to the autothermal reforming reactor and the inlet temperature of the reactor. The results indicate that further improvement in fuel processor efficiency can be made with a reliable process model.

  2. Testing Numerical Dynamo Models Against Experimental Results

    NASA Astrophysics Data System (ADS)

    Gissinger, C. J.; Fauve, S.; Dormy, E.

    2007-12-01

    Significant progress has been achieved over the past few years in describing the geomagnetic field using computer models for dynamo action. Such models are so far limited to parameter regimes which are very remote from actual values relevant to the Earth core or any liquid metal (the magnetic Prandtl number is always over estimated by a factor at least 104). While existing models successfully reproduce many of the magnetic observations, it is difficult to assert their validity. The recent success of an experimental homogeneous unconstrained dynamo (VKS) provides a new way to investigate dynamo action in turbulent conducting flows, but it also offers a chance to test the validity of exisiting numerical models. We use a code originaly written for the Geodynamo (Parody) and apply it to the experimental configuration. The direct comparison of simulations and experiments is of great interest to test the predictive value of numerical simulations for dynamo action. These turbulent simulations allow us to approach issues which are very relevant for geophysical dynamos, especially the competition between different magnetic modes and the dynamics of reversals.

  3. Nonlinear hierarchical modeling of experimental infection data.

    PubMed

    Singleton, Michael D; Breheny, Patrick J

    2016-08-01

    In this paper, we propose a nonlinear hierarchical model (NLHM) for analyzing longitudinal experimental infection (EI) data. The NLHM offers several improvements over commonly used alternatives such as repeated measures analysis of variance (RM-ANOVA) and the linear mixed model (LMM). It enables comparison of relevant biological properties of the course of infection including peak intensity, duration and time to peak, rather than simply comparing mean responses at each observation time. We illustrate the practical benefits of this model and the insights it yields using data from experimental infection studies on equine arteritis virus. Finally, we demonstrate via simulation studies that the NLHM substantially reduces bias and improves the power to detect differences in relevant features of the infection response between two populations. For example, to detect a 20% difference in response duration between two groups (n=15) in which the peak time and peak intensity were identical, the RM-ANOVA test had a power of just 11%, and LMM a power of just 12%. By comparison, the nonlinear model we propose had a power of 58% in the same scenario, while controlling the Type I error rate better than the other two methods. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Experimental models of repetitive brain injuries.

    PubMed

    Weber, John T

    2007-01-01

    Repetitive traumatic brain injury (TBI) occurs in a significant portion of trauma patients, especially in specific populations, such as child abuse victims or athletes involved in contact sports (e.g. boxing, football, hockey, and soccer). A continually emerging hypothesis is that repeated mild injuries may cause cumulative damage to the brain, resulting in long-term cognitive dysfunction. The growing attention to this hypothesis is reflected in several recent experimental studies of repeated mild TBI in vivo. These reports generally demonstrate cellular and cognitive dysfunction after repetitive injury using rodent TBI models. In some cases, data suggests that the effects of a second mild TBI may be synergistic, rather than additive. In addition, some studies have found increases in cellular markers associated with Alzheimer's disease after repeated mild injuries, which demonstrates a direct experimental link between repetitive TBI and neurodegenerative disease. To complement the findings from humans and in vivo experimentation, my laboratory group has investigated the effects of repeated trauma in cultured brain cells using a model of stretch-induced mechanical injury in vitro. In these studies, hippocampal cells exhibited cumulative damage when mild stretch injuries were repeated at either 1-h or 24-h intervals. Interestingly, the extent of damage to the cells was dependent on the time between repeated injuries. Also, a very low level of stretch, which produced no cell damage on its own, induced cell damage when it was repeated several times at a short interval (every 2 min). Although direct comparisons to the clinical situation are difficult, these types of repetitive, low-level, mechanical stresses may be similar to the insults received by certain athletes, such as boxers, or hockey and soccer players. This type of in vitro model could provide a reliable system in which to study the mechanisms underlying cellular dysfunction following repeated injuries. As

  5. Modeling and experimentally characterizing ionic buoyancy engines

    NASA Astrophysics Data System (ADS)

    Akle, Barbar J.; Nasser, Jalal; Hijazi, Ahmad

    2017-04-01

    There is a need for buoyancy engines to modulate sensor depth for optimal positioning and station-keeping. Compared to current technologies, Ionic Buoyancy Engines does not have any moving parts. They are energy efficient and miniaturization ready. Ionic Buoyancy Engines change their density by locally varying ionic concentrations in a closed chamber with a wall made of a semi-permeable membrane. The local change in concentration pumps water in and out of the chamber leading to buoyancy change. This study presents a model that is used to simulate the steady state controlled depth of the buoyancy engine, along with experimental results.

  6. Modelling Experimental Procedures for Manipulator Calibration

    DTIC Science & Technology

    1991-12-01

    AD-A245 603 NAVAL POSTGRADUATE SCHOOL Monterey, California RA D TIC THESIS F-a 1 . MODELLING EXPERIMENTAL PROCEDURES FOR MANIPULATOR CALIBRATION by...William E. Swayze December 1991 Thesis Advisor: Morris R. Driels Approved for public release; distribution is unlimited 92-03143 Uncl ass if ied...2 PERSONAL AUTHORS WILLI.TM E. SWAYZE 13a TYPE OF REPORT 13o TIME COVERED 14. DATE OF REPORT (Year, Mon.th Day) 15 PAGE COUNT Master’s Thesis FROM

  7. Graphical Models for Quasi-Experimental Designs

    ERIC Educational Resources Information Center

    Kim, Yongnam; Steiner, Peter M.; Hall, Courtney E.; Su, Dan

    2016-01-01

    Experimental and quasi-experimental designs play a central role in estimating cause-effect relationships in education, psychology, and many other fields of the social and behavioral sciences. This paper presents and discusses the causal graphs of experimental and quasi-experimental designs. For quasi-experimental designs the authors demonstrate…

  8. Modeling and experimentation of bone drilling forces.

    PubMed

    Lee, JuEun; Gozen, B Arda; Ozdoganlar, O Burak

    2012-04-05

    Prediction and control of bone drilling forces are critical to the success of many orthopaedic operations. Uncontrolled and large forces can cause drill-bit breakage, drill breakthrough, excessive heat generation, and mechanical damage to the bone. This paper presents a mechanistic model for prediction of thrust forces and torques experienced during bone drilling. The model incorporates the radially varying drill-bit geometry and cutting conditions analytically, while capturing the material and friction properties empirically through a specific energy formulation. The forces from the chisel edge are modeled by considering the indentation process that occurs in the vicinity of the drill-bit axis. A procedure is outlined to calibrate the specific energies, where only a small number of calibration experiments are required for a wide range of drilling conditions and drill-bit geometry. The calibration parameters for the cortical portions of bovine tibia are identified through drilling tests. Subsequently, a series of validation tests are conducted under different feed rates and spindle speeds. The thrust forces and torques were observed to vary considerably between bones from different animals. The forces from the model were seen to match well with those from the experimentation within the inherent variations from the bone characteristics. The model can be used to select favorable drilling conditions, to assist in robotic surgeries, and to design optimal orthopaedic drill bits. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Muscle injury: review of experimental models.

    PubMed

    Souza, Jaqueline de; Gottfried, Carmem

    2013-12-01

    Skeletal muscle is the most abundant tissue in the human body. Its main characteristic is the capacity to regenerate after injury independent of the cause of injury through a process called inflammatory response. Mechanical injuries are the most common type of the skeletal muscle injuries and are classified into one of three areas strain, contusion, and laceration. First, this review aims to describe and compare the main experimental methods that replicate the mechanical muscle injuries. There are several ways to replicate each kind of mechanical injury; there are, however, specific characteristics that must be taken into account when choosing the most appropriate model for the experiment. Finally, this review discusses the context of mechanical injury considering types, variability of methods, and the ability to reproduce injury models. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Organ models in wound ballistics: experimental study.

    PubMed

    Ozer, Mustafa Tahir; Oğünç, Gökhan; Eryilmaz, Mehmet; Yiğit, Taner; Menteş, Mustafa Oner; Dakak, Mehmet; Uzar, Ali Ihsan; Oner, Köksal

    2007-01-01

    Effects of various types and diameters of guns and related treatment principles are different. Our study was performed to experimentally demonstrate the effects of different gunshots in body tissues. 9x19 mm hand-gun and 7.62x51 mm G-3 infantry rifle were used in the study. Injury models were created through hand-gun and rifle shootings at isolated soft tissue, lower extremity, liver and intestine tissue simulants made of ballistic candle. High-speed cameras were used to capture 1000 frames per second. Images were examined and wound mechanisms were evaluated. It was observed that the colon content distributed more within the surrounding tissues by the rifle shootings comparing with hand-gun shootings and could be an infection source due to the large size of the cavity in the colon. Especially when the bullets hitting the bone were investigated, it was seen that much more tissue injury occurs with high speed bullets due to bullet deformation and fragmentation. However, no significant difference was found between the effect of hand-gun and rifle bullets passing through the extremity without hitting the bone. To know the type of the gun that caused the injury and its characteristics will allow to estimate severity and size of the injury before the treatment and to focus on different alternatives of treatment. Therefore, use of appropriate models is required in experimental studies.

  11. Experimental Oral Candidiasis in Animal Models

    PubMed Central

    Samaranayake, Yuthika H.; Samaranayake, Lakshman P.

    2001-01-01

    Oral candidiasis is as much the final outcome of the vulnerability of the host as of the virulence of the invading organism. We review here the extensive literature on animal experiments mainly appertaining to the host predisposing factors that initiate and perpetuate these infections. The monkey, rat, and mouse are the choice models for investigating oral candidiasis, but comparisons between the same or different models appear difficult, because of variables such as the study design, the number of animals used, their diet, the differences in Candida strains, and the duration of the studies. These variables notwithstanding, the following could be concluded. (i) The primate model is ideal for investigating Candida-associated denture stomatitis since both erythematous and pseudomembranous lesions have been produced in monkeys with prosthetic plates; they are, however, expensive and difficult to obtain and maintain. (ii) The rat model (both Sprague-Dawley and Wistar) is well proven for observing chronic oral candidal colonization and infection, due to the ease of breeding and handling and their ready availability. (iii) Mice are similar, but in addition there are well characterized variants simulating immunologic and genetic abnormalities (e.g., athymic, euthymic, murine-acquired immune deficiency syndrome, and severe combined immunodeficient models) and hence are used for short-term studies relating the host immune response and oral candidiasis. Nonetheless, an ideal, relatively inexpensive model representative of the human oral environment in ecological and microbiological terms is yet to be described. Until such a model is developed, researchers should pay attention to standardization of the experimental protocols described here to obtain broadly comparable and meaningful data. PMID:11292645

  12. An experimental study of human birth models

    NASA Astrophysics Data System (ADS)

    Baumer, Alexa; Gossmann, Roseanna; Fauci, Lisa J.; Leftwich, Megan C.

    2016-11-01

    The laboring uterus is a complex and dynamic fluid system. Relatively little is known about the fluid properties in this system. However, the two primary fluids of interest, amniotic fluid and vernix caseosa, likely play integral roles in the force transferred to the fetus during the final stages of parturition. This investigation probes the role of fluid in the force transfer during delivery by considering physical models that determine the role of various components of the full system. The first experimental model represents the fetus passing through the birth canal as concentric cylinders with a fluid filled gap. The rigid, inner cylinder moves through the highly flexible outer cylinder at a prescribed velocity. The geometry of the inner cylinder is varied by aspect ratio and length. A total of five different inner geometries are used to fully investigate the parameter space. As the inner cylinder moves through the outer cylinder, strain measurements are taken. These measurements are converted to force measurements as a function of time and position in the outer cylinder. The results of these experiments are compared with numerical results to form a more complete picture of force transfer. This model can be used as the foundation for predicting the force needed to deliver a fetus in the final stages of parturition. Additionally, more complex models, that incorporate uterine contraction forces, are being developed.

  13. An Experimental Itch Model in Monkeys

    PubMed Central

    Ko, M. C. Holden; Naughton, Norah N.

    2007-01-01

    Background The most common side effect of spinal opioid administration is pruritus, which has been treated with a variety of agents with variable success. Currently, there are few animal models developed to study this side effect. The aim of this study was to establish a nonhuman primate model to pharmacologically characterize the effects of intrathecal administration of morphine. Methods Eight adult rhesus monkeys were used. Scratching responses were videotaped and counted by observers who were blinded to experimental conditions. Antinociception was measured by a warm-water (50°C) tail-withdrawal assay. The dose-response of intrathecal morphine (1-320 μg) for both scratching and antinociception in all subjects was established. An opioid antagonist, nalmefene, was administered either intravenously or subcutaneously to assess its efficacy against intrathecal morphine. Results Intrathecal morphine (1-32 μg) increased scratching in a dose-dependent manner. Higher doses of intrathecal morphine (10-100 μg) produced thermal antinociception in a dose-dependent manner. On the other hand, nalmefene (10-32 μg/kg intravenously) attenuated maximum scratching responses among subjects. Pretreatment with nalmefene (32μg/kg subcutaneously) produced approximately 10-fold rightward shifts of intrathecal morphine dose-response curves for both behavioral effects. Conclusions These data indicate that intrathecal morphine-induced scratching and antinociception are mediated by opioid receptors. The magnitude of nalmefene antagonism of intrathecal morphine is consistent with μ opioid receptor mediation. This experimental itch model is useful for evaluating different agents that may suppress scratching without interfering with antinociception. It may also facilitate the clarification of mechanisms underlying these phenomena. PMID:10719958

  14. Colonic perianastomotic carcinogenesis in an experimental model

    PubMed Central

    Pérez-Holanda, Sergio; Rodrigo, Luis; Pinyol-Felis, Carme; Vinyas-Salas, Joan

    2008-01-01

    Background To examine the effect of anastomosis on experimental carcinogenesis in the colon of rats. Methods Forty-three 10-week-old male and female Sprague-Dawley rats were operated on by performing an end-to-side ileorectostomy. Group A:16 rats received no treatment. Group B: 27 rats received 18 subcutaneous injections weekly at a dose of 21 mg/kg wt of 1–2 dimethylhydrazine (DMH), from the eighth day after the intervention. Animals were sacrificed between 25–27 weeks. The number of tumours, their localization, size and microscopic characteristics were recorded. A paired chi-squared analysis was performed comparing tumoral induction in the perianastomotic zone with the rest of colon with faeces. Results No tumours appeared in the dimethylhydrazine-free group. The percentage tumoral area was greater in the perianastomotic zone compared to tumours which had developed in the rest of colon with faeces (p = 0.014). Conclusion We found a cocarcinogenic effect due to the creation of an anastomosis, when using an experimental model of colonic carcinogenesis induced by DMH in rats. PMID:18667092

  15. Prediction of catastrophes: an experimental model.

    PubMed

    Peters, Randall D; Le Berre, Martine; Pomeau, Yves

    2012-08-01

    Catastrophes of all kinds can be roughly defined as short-duration, large-amplitude events following and followed by long periods of "ripening." Major earthquakes surely belong to the class of "catastrophic" events. Because of the space-time scales involved, an experimental approach is often difficult, not to say impossible, however desirable it could be. Described in this article is a "laboratory" setup that yields data of a type that is amenable to theoretical methods of prediction. Observations are made of a critical slowing down in the noisy signal of a solder wire creeping under constant stress. This effect is shown to be a fair signal of the forthcoming catastrophe in two separate dynamical models. The first is an "abstract" model in which a time-dependent quantity drifts slowly but makes quick jumps from time to time. The second is a realistic physical model for the collective motion of dislocations (the Ananthakrishna set of equations for unstable creep). Hope thus exists that similar changes in the response to noise could forewarn catastrophes in other situations, where such precursor effects should manifest early enough.

  16. Effects of Anethole in Nociception Experimental Models

    PubMed Central

    Ritter, Alessandra Mileni Versuti; Ames, Franciele Queiroz; Otani, Fernando; de Oliveira, Rubia Maria Weffort; Cuman, Roberto Kenji Nakamura; Bersani-Amado, Ciomar Aparecida

    2014-01-01

    This study investigated the antinociceptive activity of anethole (anethole 1-methoxy-4-benzene (1-propenyl)), major compound of the essential oil of star anise (Illicium verum), in different experimental models of nociception. The animals were pretreated with anethole (62.5, 125, 250, and 500 mg/kg) one hour before the experiments. To eliminate a possible sedative effect of anethole, the open field test was conducted. Anethole (62.5, 125, 250, and 500 mg/kg) showed an antinociceptive effect in the writhing model induced by acetic acid, in the second phase of the formalin test (125 and 250 mg/kg) in the test of glutamate (62.5, 125, and 250 mg/kg), and expresses pain induced by ACF (250 mg/kg). In contrast, anethole was not able to increase the latency time on the hot plate and decrease the number of flinches during the initial phase of the formalin test in any of the doses tested. It was also demonstrated that anethole has no association with sedative effects. Therefore, these data showed that anethole, at all used doses, has no sedative effect and has an antinociceptive effect. This effect may be due to a decrease in the production/release of inflammatory mediators. PMID:25506382

  17. Effects of anethole in nociception experimental models.

    PubMed

    Ritter, Alessandra Mileni Versuti; Ames, Franciele Queiroz; Otani, Fernando; de Oliveira, Rubia Maria Weffort; Cuman, Roberto Kenji Nakamura; Bersani-Amado, Ciomar Aparecida

    2014-01-01

    This study investigated the antinociceptive activity of anethole (anethole 1-methoxy-4-benzene (1-propenyl)), major compound of the essential oil of star anise (Illicium verum), in different experimental models of nociception. The animals were pretreated with anethole (62.5, 125, 250, and 500 mg/kg) one hour before the experiments. To eliminate a possible sedative effect of anethole, the open field test was conducted. Anethole (62.5, 125, 250, and 500 mg/kg) showed an antinociceptive effect in the writhing model induced by acetic acid, in the second phase of the formalin test (125 and 250 mg/kg) in the test of glutamate (62.5, 125, and 250 mg/kg), and expresses pain induced by ACF (250 mg/kg). In contrast, anethole was not able to increase the latency time on the hot plate and decrease the number of flinches during the initial phase of the formalin test in any of the doses tested. It was also demonstrated that anethole has no association with sedative effects. Therefore, these data showed that anethole, at all used doses, has no sedative effect and has an antinociceptive effect. This effect may be due to a decrease in the production/release of inflammatory mediators.

  18. ARCJET plasma modeling with experimental validation

    NASA Astrophysics Data System (ADS)

    Krier, Herman; Burton, Rodney L.; Megli, Thomas W.; Bufton, Scott A.; Tiliakos, Nicholas T.

    1994-09-01

    We report for the first time thermal non-equilibrium (separate electron and gas temperatures) numerical results for a hydrazine arcjet. All viscous flow properties are considered, assuming laminar axisymmetric flow. The model includes anode temperature distribution, and the electrical conductivity is coupled to the flow properties, allowing for a self-consistent current distribution. The numerical solution algorithm employs the compressible form of the PISO algorithm to solve the continuity and momentum equations. Run time is a few hours on a Convex C240 Mainframe with a 44 x 24 grid. Numerical results are presented for low power hydrogen and hydrazine thrusters. Preliminary results of quadruple electrostatic probe measurements at the exit plane of a 1 kW hydrazine arcjet, including ne and Te profiles, are presented. The quadruple probe model includes the effects of Te and Ne gradients across the probe volume to extract Te and Ne radial profiles from the asymmetric raw probe data. A time-of-flight electrostatic probe technique for measuring heavy particle velocities is described which, when coupled with the quadruple probe data can yield radial profiles of Ne(r), Te(r), Ti(r) and Ui(r). Experimental investigations of the energy deposition processes in the nozzle and constrictor regions of a 1-2 kill hydrazine arcjet are being performed. Electron number density and electron temperature measurements, using an array of flush-mounted Langmuir probes, will be made in the boundary layer.

  19. Experimental models for Murray’s law

    NASA Astrophysics Data System (ADS)

    Akita, Dai; Kunita, Itsuki; Fricker, Mark D.; Kuroda, Shigeru; Sato, Katsuhiko; Nakagaki, Toshiyuki

    2017-01-01

    Transport networks are ubiquitous in multicellular organisms and include leaf veins, fungal mycelia and blood vessels. While transport of materials and signals through the network plays a crucial role in maintaining the living system, the transport capacity of the network can best be understood in terms of hydrodynamics. We report here that plasmodium from the large, single-celled amoeboid Physarum was able to construct a hydrodynamically optimized vein-network when evacuating biomass from confined arenas of various shapes through a narrow exit. Increasingly thick veins developed towards the exit, and the network spanned the arena via repetitive bifurcations to give a branching tree. The Hausdorff distance from all parts of the plasmodium to the vein network was kept low, whilst the hydrodynamic conductivity from distal parts of the network to the exit was equivalent, irrespective of the arena shape. This combination of spatial patterning and differential vein thickening served to evacuate biomass at an equivalent rate across the entire arena. The scaling relationship at the vein branches was determined experimentally to be 2.53-3.29, consistent with predictions from Murray’s law. Furthermore, we show that mathematical models for self-organised, adaptive transport in Physarum simulate the experimental network organisation well if the scaling coefficient of the current-reinforcement rule is set to 3. In simulations, this resulted in rapid development of an optimal network that minimised the combined volume and frictional energy in comparison with other scaling coefficients. This would predict that the boundary shear forces within each vein are constant throughout the network, and would be consistent with a feedback mechanism based on a sensing a threshold shear at the vein wall.

  20. Experimental murine model of renal cancer.

    PubMed

    Padilla-Fernández, B; García-Cenador, M B; Rodríguez-Marcos, P; López-Marcos, J F; Antúnez-Plaza, P; Silva-Abuín, J M; López-Montañés, D; García-Criado, F J; Lorenzo-Gómez, M F

    2017-09-01

    The objective of this study was to determine the reproducibility in a murine model of renal tumours of various histological strains that could be useful for investigating the response to target drugs. Development and analysis of the "in vivo" model: tumour xenograft of renal cell carcinomas with Balb/c nude athymic mice. Nontumourous human renal tissue was implanted in the interscapular region of 5 mice, chromophobe renal cell carcinoma was implanted in 5 mice (which, after checking its growth, was prepared for implantation in another 10 mice) and Fuhrman grade 2 clear cell renal cell carcinoma (CCRCC) was implanted in 5 mice (which was also subsequently implanted in 10 mice). We monitored the tumour size, onset of metastases and increase in size and number of tumours. When the size had reached a point greater than or equal to locally advanced or metastatic carcinoma, the animals were euthanised for a pathological and immunohistochemical study and a second phase of implantation. The subcutaneous xenograft of the healthy tissue did not grow. The animals were euthanised at 6 months and no renal tissue was found. The chromophobe renal cell carcinoma cells grew in the initial phase (100%); however, in the second phase, we observed a chronic lymphomonocyte inflammatory reaction and a foreign body reaction. The CCRCC grew at 5-8 months both in the first and second phase (100%), maintaining the tumour type and grade. The model with athymic Balb/c nude mice is useful for reproducing CCRCC, with the same histological characteristics and aggressiveness as native human tumours, promoting the development of the second experimental phase. Copyright © 2016 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.

  1. Experimental, Numerical and Observational Models in Geodynamics

    NASA Astrophysics Data System (ADS)

    Lithgow-Bertelloni, Carolina

    2015-04-01

    Geodynamics, the study of the forces that drives all Earth's processes is a rich field that deeply connects all aspects of geological and geophysical studies, from surface observations of the sedimentary record to knowledge of deep Earth structure from mineral physics and seismology. In the context of the solid Earth geodynamics primarily focuses on lithosphere and mantle dynamics, while core dynamics is the purview of geomagnetism. I will focus this talk on the former, its historical context and future developments. We have known the equations of motion and mechanics for ~200 years, but only relatively recently can they be solved with enough accuracy and resolution to do geology. We have made great strides since Arthur Holmes conceptual models of mantle flow, thanks to computational and experimental advances. We can know model plate boundaries globally with resolutions in the order of a few kms and image temperature and velocity simultaneously in the laboratory in 3D and non-intrusively. We have also learned a great deal about the physics of the Earth, from composition to rheology. New theories on plate boundary rheology are paving the way for self-consistent generation of plates from mantle flow. New computational methods allow for adaptive meshing, fabric development and history, so we can study deformation and compare directly to geological observations in mountain ranges and continental rifts. We can use ever more sophisticated images of mantle structure from seismic and other geophysical data to probe the relationship between melting, flow and dynamical processes. We can reconstruct landscapes and relief, plate motions and sedimentation and ask how much the mantle has contributed to drainage reversal, sedimentation and climate change. The future of the field is ever brighter.

  2. Experimental model to study sedimentary kidney stones.

    PubMed

    Grases, F; Llobera, A

    1998-01-01

    An experimental model to reproduce, to some extent, the conditions prevailing during the formation of the so-called sedimentary urinary stones, was developed. The results obtained demonstrated that in the absence of organic matter no calcium phosphate crystals were deposited in cavities with scarce liquid renovation. Nevertheless, in such case a regular hydroxyapatite layer was developed on the walls around the cavity. The presence of crystallization inhibitors cannot stop indefinitely the crystal development. Therefore, phytate manifested important inhibitory effects in concentrations normally found in urine (0.77-1.54 x 10(-6) mol/l), whereas citrate only manifested important inhibitory effects when found at high urinary concentrations (2.64 x 10(-3) mol/l). When mucin (a glycoprotein) was present in the urine, a clear deposit of calcified organic material was formed. The organic matter appeared mixed with the spherulites of hydroxyapatite, this demonstrating the capacity of the glycoprotein agglomerates to act as heterogeneous nucleants of calcium salts and their important role in the formation of sedimentary stones. The structural features of the obtained in vitro deposits were compared with the fine structure of human sedimentary phosphate calculi. Scanning electron microscopy images demonstrated a good correspondence between in vitro experiments and in vivo observations.

  3. Experimental modelling of outburst flood - bed interactions

    NASA Astrophysics Data System (ADS)

    Carrivick, J. L.; Xie, Z.; Sleigh, A.; Hubbard, M.

    2009-04-01

    Outburst floods are a sudden release and advancing wave of water and sediment, with a peak discharge that is often several orders of magnitude greater than perennial flows. Common outburst floods from natural sources include those from glacial and moraine-impounded lakes, freshwater dyke and levee bursts, volcanic debris dams, landslides, avalanches, coastal bay-bars, and those from tree or vegetation dams. Outburst flood hazards are regularly incorporated into risk assessments for urban, coastal and mountainous areas, for example. Outburst flood hazards are primarily due to direct impacts, caused by a frontal surge wave, from debris within a flow body, and from the mass and consistency of the flows. A number of secondary impacts also pose hazards, including widespread deposition of sediment and blocked tributary streams. It is rapid landscape change, which is achieved the mobilization and redistribution of sediment that causes one of the greatest hazards due to outburst floods. The aim of this project is therefore to parameterise hydrodynamic - sedimentary interactions in experimental outburst floods. Specifically, this project applies laboratory flume modelling, which offers a hitherto untapped opportunity for examining complex interactions between water and sediment within outburst floods. The experimental set-up is of a tradition lock-gate design with a straight 4 m long tank. Hydraulics are scaled at 1:20 froude scale and the following controls on frontal wave flow-bed interactions and hence on rapid landscape change are being investigated: 1. Pre-existing mobile sediment effects, fixed bed roughness effects, sediment concentration effects, mobile bed effects. An emphasis is being maintained on examining the downstream temporal and spatial change in physical character of the water / sediment frontal wave. Facilities are state-of-the-art with a fully-automated laser bed-profiler to measure bed elevation after a run, Seatek arrays to measure transient flow

  4. Experimental & Numerical Modeling of Non-combusting Model Firebrands' Transport

    NASA Astrophysics Data System (ADS)

    Tohidi, Ali; Kaye, Nigel

    2016-11-01

    Fire spotting is one of the major mechanisms of wildfire spread. Three phases of this phenomenon are firebrand formation and break-off from burning vegetation, lofting and downwind transport of firebrands through the velocity field of the wildfire, and spot fire ignition upon landing. The lofting and downwind transport phase is modeled by conducting large-scale wind tunnel experiments. Non-combusting rod-like model firebrands with different aspect ratios are released within the velocity field of a jet in a boundary layer cross-flow that approximates the wildfire velocity field. Characteristics of the firebrand dispersion are quantified by capturing the full trajectory of the model firebrands using the developed image processing algorithm. The results show that the lofting height has a direct impact on the maximum travel distance of the model firebrands. Also, the experimental results are utilized for validation of a highly scalable coupled stochastic & parametric firebrand flight model that, couples the LES-resolved velocity field of a jet-in-nonuniform-cross-flow (JINCF) with a 3D fully deterministic 6-degrees-of-freedom debris transport model. The validation results show that the developed numerical model is capable of estimating average statistics of the firebrands' flight. Authors would like to thank support of the National Science Foundation under Grant No. 1200560. Also, the presenter (Ali Tohid) would like to thank Dr. Michael Gollner from the University of Maryland College Park for the conference participation support.

  5. Biomass thermochemical gasification: Experimental studies and modeling

    NASA Astrophysics Data System (ADS)

    Kumar, Ajay

    The overall goals of this research were to study the biomass thermochemical gasification using experimental and modeling techniques, and to evaluate the cost of industrial gas production and combined heat and power generation. This dissertation includes an extensive review of progresses in biomass thermochemical gasification. Product gases from biomass gasification can be converted to biopower, biofuels and chemicals. However, for its viable commercial applications, the study summarizes the technical challenges in the gasification and downstream processing of product gas. Corn stover and dried distillers grains with solubles (DDGS), a non-fermentable byproduct of ethanol production, were used as the biomass feedstocks. One of the objectives was to determine selected physical and chemical properties of corn stover related to thermochemical conversion. The parameters of the reaction kinetics for weight loss were obtained. The next objective was to investigate the effects of temperature, steam to biomass ratio and equivalence ratio on gas composition and efficiencies. DDGS gasification was performed on a lab-scale fluidized-bed gasifier with steam and air as fluidizing and oxidizing agents. Increasing the temperature resulted in increases in hydrogen and methane contents and efficiencies. A model was developed to simulate the performance of a lab-scale gasifier using Aspen Plus(TM) software. Mass balance, energy balance and minimization of Gibbs free energy were applied for the gasification to determine the product gas composition. The final objective was to optimize the process by maximizing the net energy efficiency, and to estimate the cost of industrial gas, and combined heat and power (CHP) at a biomass feedrate of 2000 kg/h. The selling price of gas was estimated to be 11.49/GJ for corn stover, and 13.08/GJ for DDGS. For CHP generation, the electrical and net efficiencies were 37 and 86%, respectively for corn stover, and 34 and 78%, respectively for DDGS. For

  6. Experimentally Induced Mammalian Models of Glaucoma

    PubMed Central

    Yoshitomi, Takeshi; Zorumski, Charles F.; Izumi, Yukitoshi

    2015-01-01

    A wide variety of animal models have been used to study glaucoma. Although these models provide valuable information about the disease, there is still no ideal model for studying glaucoma due to its complex pathogenesis. Animal models for glaucoma are pivotal for clarifying glaucoma etiology and for developing novel therapeutic strategies to halt disease progression. In this review paper, we summarize some of the major findings obtained in various glaucoma models and examine the strengths and limitations of these models. PMID:26064891

  7. Graphical Models for Quasi-Experimental Designs

    ERIC Educational Resources Information Center

    Steiner, Peter M.; Kim, Yongnam; Hall, Courtney E.; Su, Dan

    2017-01-01

    Randomized controlled trials (RCTs) and quasi-experimental designs like regression discontinuity (RD) designs, instrumental variable (IV) designs, and matching and propensity score (PS) designs are frequently used for inferring causal effects. It is well known that the features of these designs facilitate the identification of a causal estimand…

  8. Experimental modeling of cavitation occurring at vibration

    NASA Astrophysics Data System (ADS)

    Gaynutdinova, D. F.; Modorskii, V. Ya.; Shevelev, N. A.

    2016-10-01

    The article investigates the problem of effects in two-stage centrifugal pumps due to hydro-gas-dynamic processes resulting from vibrations of design elements which are difficult to forecast. Numerical and experimental simulation of this problem was conducted. The experiment discovered cavitation effects brought about by the vibrations. The area of cavitations was plotted. Dependence of cavitation bubble concentration on amplitude and frequency of the vibrations was found.

  9. Experimental model of atelectasis in newborn piglets.

    PubMed

    Comaru, Talitha; Fiori, Humberto Holmer; Fiori, Renato Machado; Padoim, Priscila; Stivanin, Jaqueline Basso; da Silva, Vinicius Duval

    2014-01-01

    There are few studies using animal models in chest physical therapy. However, there are no models to assess these effects in newborns. This study aimed to develop a model of obstructive atelectasis induced by artificial mucus injection in the lungs of newborn piglets, for the study of neonatal physiotherapy. Thirteen newborn piglets received artificial mucus injection via the endotracheal tube. X-rays and blood gas analysis confirmed the atelectasis. The model showed consistent results between oxygenation parameters and radiological findings. Ten (76.9%) of the 13 piglets responded to the intervention. This did not significantly differ from the expected percentage of 50% by the binomial test (95% CI 46.2-95%, P = .09). Our model of atelectasis in newborn piglets is both feasible and appropriate to evaluate the impact of physical therapies on atelectasis in newborns.

  10. Experimental Diabetes Mellitus in Different Animal Models.

    PubMed

    Al-Awar, Amin; Kupai, Krisztina; Veszelka, Médea; Szűcs, Gergő; Attieh, Zouhair; Murlasits, Zsolt; Török, Szilvia; Pósa, Anikó; Varga, Csaba

    2016-01-01

    Animal models have historically played a critical role in the exploration and characterization of disease pathophysiology and target identification and in the evaluation of novel therapeutic agents and treatments in vivo. Diabetes mellitus disease, commonly known as diabetes, is a group of metabolic disorders characterized by high blood glucose levels for a prolonged time. To avoid late complications of diabetes and related costs, primary prevention and early treatment are therefore necessary. Due to its chronic symptoms, new treatment strategies need to be developed, because of the limited effectiveness of the current therapies. We overviewed the pathophysiological features of diabetes in relation to its complications in type 1 and type 2 mice along with rat models, including Zucker Diabetic Fatty (ZDF) rats, BB rats, LEW 1AR1/-iddm rats, Goto-Kakizaki rats, chemically induced diabetic models, and Nonobese Diabetic mouse, and Akita mice model. The advantages and disadvantages that these models comprise were also addressed in this review. This paper briefly reviews the wide pathophysiological and molecular mechanisms associated with type 1 and type 2 diabetes, particularly focusing on the challenges associated with the evaluation and predictive validation of these models as ideal animal models for preclinical assessments and discovering new drugs and therapeutic agents for translational application in humans.

  11. Experimentally validated finite element model of electrocaloric multilayer ceramic structures

    NASA Astrophysics Data System (ADS)

    Smith, N. A. S.; Rokosz, M. K.; Correia, T. M.

    2014-07-01

    A novel finite element model to simulate the electrocaloric response of a multilayer ceramic capacitor (MLCC) under real environment and operational conditions has been developed. The two-dimensional transient conductive heat transfer model presented includes the electrocaloric effect as a source term, as well as accounting for radiative and convective effects. The model has been validated with experimental data obtained from the direct imaging of MLCC transient temperature variation under application of an electric field. The good agreement between simulated and experimental data, suggests that the novel experimental direct measurement methodology and the finite element model could be used to support the design of optimised electrocaloric units and operating conditions.

  12. Experimentally validated finite element model of electrocaloric multilayer ceramic structures

    SciTech Connect

    Smith, N. A. S. E-mail: maciej.rokosz@npl.co.uk Correia, T. M. E-mail: maciej.rokosz@npl.co.uk; Rokosz, M. K. E-mail: maciej.rokosz@npl.co.uk

    2014-07-28

    A novel finite element model to simulate the electrocaloric response of a multilayer ceramic capacitor (MLCC) under real environment and operational conditions has been developed. The two-dimensional transient conductive heat transfer model presented includes the electrocaloric effect as a source term, as well as accounting for radiative and convective effects. The model has been validated with experimental data obtained from the direct imaging of MLCC transient temperature variation under application of an electric field. The good agreement between simulated and experimental data, suggests that the novel experimental direct measurement methodology and the finite element model could be used to support the design of optimised electrocaloric units and operating conditions.

  13. Cooking Potatoes: Experimentation and Mathematical Modeling.

    ERIC Educational Resources Information Center

    Chen, Xiao Dong

    2002-01-01

    Describes a laboratory activity involving a mathematical model of cooking potatoes that can be solved analytically. Highlights the microstructure aspects of the experiment. Provides the key aspects of the results, detailed background readings, laboratory procedures and data analyses. (MM)

  14. Cooking Potatoes: Experimentation and Mathematical Modeling.

    ERIC Educational Resources Information Center

    Chen, Xiao Dong

    2002-01-01

    Describes a laboratory activity involving a mathematical model of cooking potatoes that can be solved analytically. Highlights the microstructure aspects of the experiment. Provides the key aspects of the results, detailed background readings, laboratory procedures and data analyses. (MM)

  15. Experimental Septic Shock: Models and Mechanisms

    DTIC Science & Technology

    1976-06-14

    E . coli endotoxin or live E . coli organisms were evaluated during a 24-hour period or until death. Results suggest significant differences between the two shock models: large dosages of endotoxin on contrast to those used in the canine species were required to elicit lethality characteristics. Hypoglycemia and hypoinsulinemia were regularly observed in live E . coli organism induced shock; however, hyperglycemia was a consistent hallmark in the endotoxin infused model. Renal fibrin thrombi were presented only after E .

  16. Gear Windage Modeling Progress - Experimental Validation Status

    NASA Technical Reports Server (NTRS)

    Kunz, Rob; Handschuh, Robert F.

    2008-01-01

    In the Subsonics Rotary Wing (SRW) Project being funded for propulsion work at NASA Glenn Research Center, performance of the propulsion system is of high importance. In current rotorcraft drive systems many gearing components operate at high rotational speed (pitch line velocity > 24000 ft/ min). In our testing of high speed helical gear trains at NASA Glenn we have found that the work done on the air - oil mist within the gearbox can become a significant part of the power loss of the system. This loss mechanism is referred to as windage. The effort described in this presentation is to try to understand the variables that affect windage, develop a good experimental data base to validate, the analytical project being conducted at Penn State University by Dr. Rob Kunz under a NASA SRW NRA. The presentation provides an update to the status of these efforts.

  17. Experimental Design and Multiplexed Modeling Using Titrimetry and Spreadsheets

    NASA Astrophysics Data System (ADS)

    Harrington, Peter De B.; Kolbrich, Erin; Cline, Jennifer

    2002-07-01

    The topics of experimental design and modeling are important for inclusion in the undergraduate curriculum. Many general chemistry and quantitative analysis courses introduce students to spreadsheet programs, such as MS Excel. Students in the laboratory sections of these courses use titrimetry as a quantitative measurement method. Unfortunately, the only model that students may be exposed to in introductory chemistry courses is the working curve that uses the linear model. A novel experiment based on a multiplex model has been devised for titrating several vinegar samples at a time. The multiplex titration can be applied to many other routine determinations. An experimental design model is fit to titrimetric measurements using the MS Excel LINEST function to estimate concentration from each sample. This experiment provides valuable lessons in error analysis, Class A glassware tolerances, experimental simulation, statistics, modeling, and experimental design.

  18. Experimental evaluations of the microchannel flow model

    NASA Astrophysics Data System (ADS)

    Parker, K. J.

    2015-06-01

    Recent advances have enabled a new wave of biomechanics measurements, and have renewed interest in selecting appropriate rheological models for soft tissues such as the liver, thyroid, and prostate. The microchannel flow model was recently introduced to describe the linear response of tissue to stimuli such as stress relaxation or shear wave propagation. This model postulates a power law relaxation spectrum that results from a branching distribution of vessels and channels in normal soft tissue such as liver. In this work, the derivation is extended to determine the explicit link between the distribution of vessels and the relaxation spectrum. In addition, liver tissue is modified by temperature or salinity, and the resulting changes in tissue responses (by factors of 1.5 or greater) are reasonably predicted from the microchannel flow model, simply by considering the changes in fluid flow through the modified samples. The 2 and 4 parameter versions of the model are considered, and it is shown that in some cases the maximum time constant (corresponding to the minimum vessel diameters), could be altered in a way that has major impact on the observed tissue response. This could explain why an inflamed region is palpated as a harder bump compared to surrounding normal tissue.

  19. Experimental evaluations of the microchannel flow model.

    PubMed

    Parker, K J

    2015-06-07

    Recent advances have enabled a new wave of biomechanics measurements, and have renewed interest in selecting appropriate rheological models for soft tissues such as the liver, thyroid, and prostate. The microchannel flow model was recently introduced to describe the linear response of tissue to stimuli such as stress relaxation or shear wave propagation. This model postulates a power law relaxation spectrum that results from a branching distribution of vessels and channels in normal soft tissue such as liver. In this work, the derivation is extended to determine the explicit link between the distribution of vessels and the relaxation spectrum. In addition, liver tissue is modified by temperature or salinity, and the resulting changes in tissue responses (by factors of 1.5 or greater) are reasonably predicted from the microchannel flow model, simply by considering the changes in fluid flow through the modified samples. The 2 and 4 parameter versions of the model are considered, and it is shown that in some cases the maximum time constant (corresponding to the minimum vessel diameters), could be altered in a way that has major impact on the observed tissue response. This could explain why an inflamed region is palpated as a harder bump compared to surrounding normal tissue.

  20. Ideal Experimental Rat Models for Liver Diseases.

    PubMed

    Lee, Sang Woo; Kim, Sung Hoon; Min, Seon Ok; Kim, Kyung Sik

    2011-05-01

    There are many limitations for conducting liver disease research in human beings due to the high cost and potential ethical issues. For this reason, conducting a study that is difficult to perform in humans using appropriate animal models, can be beneficial in ascertaining the pathological physiology, and in developing new treatment modalities. However, it is difficult to determine the appropriate animal model which is suitable for research purposes, since every patient has different and diverse clinical symptoms, adverse reactions, and complications due to the pathological physiology. Also, it is not easy to reproduce identically various clinical situations in animal models. Recently, the Guide for the Care and Use of Laboratory Animals has tightened up the regulations, and therefore it is advisable to select the appropriate animals and decide upon the appropriate quantities through scientific and systemic considerations before conducting animal testing. Therefore, in this review article the authors examined various white rat animal testing models and determined the appropriate usable rat model, and the pros and cons of its application in liver disease research. The authors believe that this review will be beneficial in selecting proper laboratory animals for research purposes.

  1. Modeling Graves' Orbitopathy in Experimental Graves' Disease.

    PubMed

    Banga, J P; Moshkelgosha, S; Berchner-Pfannschmidt, U; Eckstein, A

    2015-09-01

    Graves' orbitopathy (GO), also known as thyroid eye disease is an inflammatory disease of the orbital tissue of the eye that arises as a consequence of autoimmune thyroid disease. The central feature of the disease is the production of antibodies to the thyrotropin hormone receptor (TSHR) that modulate the function of the receptor leading to autoimmune hyperthyroidism and GO. Over the years, all viable preclinical models of Graves' disease have been incomplete and singularly failed to progress in the treatment of orbital complications. A new mouse model of GO based upon immunogenic presentation of human TSHR A-subunit plasmid by close field electroporation is shown to lead to induction of prolonged functional antibodies to TSHR resulting in chronic disease with subsequent progression to GO. The stable preclinical GO model exhibited pathologies reminiscent of human disease characterized by orbital remodeling by inflammation and adipogenesis. Inflammatory lesions characterized by CD3+ T cells and macrophages were localized in the orbital muscle tissue. This was accompanied by extensive adipogenesis of orbital fat in some immune animals. Surprisingly, other signs of orbital involvement were reminiscent of eyelid inflammation involving chemosis, with dilated and congested orbital blood vessels. More recently, the model is replicated in the author's independent laboratories. The pre-clinical model will provide the basis to study the pathogenic and regulatory roles of immune T and B cells and their subpopulations to understand the initiation, pathophysiology, and progression of GO. © Georg Thieme Verlag KG Stuttgart · New York.

  2. Ideal Experimental Rat Models for Liver Diseases

    PubMed Central

    Lee, Sang Woo; Kim, Sung Hoon; Min, Seon Ok

    2011-01-01

    There are many limitations for conducting liver disease research in human beings due to the high cost and potential ethical issues. For this reason, conducting a study that is difficult to perform in humans using appropriate animal models, can be beneficial in ascertaining the pathological physiology, and in developing new treatment modalities. However, it is difficult to determine the appropriate animal model which is suitable for research purposes, since every patient has different and diverse clinical symptoms, adverse reactions, and complications due to the pathological physiology. Also, it is not easy to reproduce identically various clinical situations in animal models. Recently, the Guide for the Care and Use of Laboratory Animals has tightened up the regulations, and therefore it is advisable to select the appropriate animals and decide upon the appropriate quantities through scientific and systemic considerations before conducting animal testing. Therefore, in this review article the authors examined various white rat animal testing models and determined the appropriate usable rat model, and the pros and cons of its application in liver disease research. The authors believe that this review will be beneficial in selecting proper laboratory animals for research purposes. PMID:26421020

  3. Experimental models and mechanisms of enhanced coughing

    PubMed Central

    Bolser, Donald C.

    2011-01-01

    Enhanced coughing can be produced in a variety of animal models, including the guinea pig, cat, dog and pig. Typically, airway inflammation has been produced by sensitization, exposure to cigarette smoke, sulphur dioxide or angiotensin-converting enzyme inhibitors. In some of these models, inflammatory mediators such as bradykinin and tachykinins have been shown to contribute to the enhanced coughing. While most of these studies have focussed on peripheral mechanisms, increases in central excitability of the cough reflex have been shown to occur as a result of airway inflammation. As such, we propose that enhanced coughing in pathological conditions is the result of plastic changes in both peripheral and central neural elements. Furthermore, we present a modified model of the neurogenesis of cough that takes into account peripheral and central plasticity induced by mediators of inflammation. PMID:15564080

  4. Scaled Experimental Modeling of VHTR Plenum Flows

    SciTech Connect

    ICONE 15

    2007-04-01

    Abstract The Very High Temperature Reactor (VHTR) is the leading candidate for the Next Generation Nuclear Power (NGNP) Project in the U.S. which has the goal of demonstrating the production of emissions free electricity and hydrogen by 2015. Various scaled heated gas and water flow facilities were investigated for modeling VHTR upper and lower plenum flows during the decay heat portion of a pressurized conduction-cooldown scenario and for modeling thermal mixing and stratification (“thermal striping”) in the lower plenum during normal operation. It was concluded, based on phenomena scaling and instrumentation and other practical considerations, that a heated water flow scale model facility is preferable to a heated gas flow facility and to unheated facilities which use fluids with ranges of density to simulate the density effect of heating. For a heated water flow lower plenum model, both the Richardson numbers and Reynolds numbers may be approximately matched for conduction-cooldown natural circulation conditions. Thermal mixing during normal operation may be simulated but at lower, but still fully turbulent, Reynolds numbers than in the prototype. Natural circulation flows in the upper plenum may also be simulated in a separate heated water flow facility that uses the same plumbing as the lower plenum model. However, Reynolds number scaling distortions will occur at matching Richardson numbers due primarily to the necessity of using a reduced number of channels connected to the plenum than in the prototype (which has approximately 11,000 core channels connected to the upper plenum) in an otherwise geometrically scaled model. Experiments conducted in either or both facilities will meet the objectives of providing benchmark data for the validation of codes proposed for NGNP designs and safety studies, as well as providing a better understanding of the complex flow phenomena in the plenums.

  5. Software reliability: Repetitive run experimentation and modeling

    NASA Technical Reports Server (NTRS)

    Nagel, P. M.; Skrivan, J. A.

    1982-01-01

    A software experiment conducted with repetitive run sampling is reported. Independently generated input data was used to verify that interfailure times are very nearly exponentially distributed and to obtain good estimates of the failure rates of individual errors and demonstrate how widely they vary. This fact invalidates many of the popular software reliability models now in use. The log failure rate of interfailure time was nearly linear as a function of the number of errors corrected. A new model of software reliability is proposed that incorporates these observations.

  6. Process Model Construction and Optimization Using Statistical Experimental Design,

    DTIC Science & Technology

    1988-04-01

    Memo No. 88-442 ~LECTE March 1988 31988 %,.. MvAY 1 98 0) PROCESS MODEL CONSTRUCTION AND OPTIMIZATION USING STATISTICAL EXPERIMENTAL DESIGN Emmanuel...Sachs and George Prueger Abstract A methodology is presented for the construction of process models by the combination of physically based mechanistic...253-8138. .% I " Process Model Construction and Optimization Using Statistical Experimental Design" by Emanuel Sachs Assistant Professor and George

  7. Experimental Control of Simple Pendulum Model

    ERIC Educational Resources Information Center

    Medina, C.

    2004-01-01

    This paper conveys information about a Physics laboratory experiment for students with some theoretical knowledge about oscillatory motion. Students construct a simple pendulum that behaves as an ideal one, and analyze model assumption incidence on its period. The following aspects are quantitatively analyzed: vanishing friction, small amplitude,…

  8. Experimental Control of Simple Pendulum Model

    ERIC Educational Resources Information Center

    Medina, C.

    2004-01-01

    This paper conveys information about a Physics laboratory experiment for students with some theoretical knowledge about oscillatory motion. Students construct a simple pendulum that behaves as an ideal one, and analyze model assumption incidence on its period. The following aspects are quantitatively analyzed: vanishing friction, small amplitude,…

  9. Experimental models for hepatitis C viral infection.

    PubMed

    Boonstra, Andre; van der Laan, Luc J W; Vanwolleghem, Thomas; Janssen, Harry L A

    2009-11-01

    Hepatitis C virus (HCV) infection is a leading cause of chronic liver disease. The majority of infected individuals develop a persistent infection, which is associated with a high risk of liver cirrhosis and hepatocellular carcinoma. Since its discovery 20 years ago, progress in our understanding of this virus has been suboptimal due to the lack of good model systems. However, in the past decade this has greatly accelerated with the development of various in vitro cell culture systems and in vivo small-animal models. These systems have made a major impact on the field of HCV research, and have provided important breakthroughs in our understanding of HCV infection and replication. Importantly, the in vitro cell culture systems and the small-animal models have allowed preclinical testing of numerous novel antiviral compounds for the treatment of chronic HCV infection. In this article, we give an overview of current models, discuss their limitations, and provide future perspectives for research directed at the prevention and cure of hepatitis C.

  10. Model Selection in Systems Biology Depends on Experimental Design

    PubMed Central

    Silk, Daniel; Kirk, Paul D. W.; Barnes, Chris P.; Toni, Tina; Stumpf, Michael P. H.

    2014-01-01

    Experimental design attempts to maximise the information available for modelling tasks. An optimal experiment allows the inferred models or parameters to be chosen with the highest expected degree of confidence. If the true system is faithfully reproduced by one of the models, the merit of this approach is clear - we simply wish to identify it and the true parameters with the most certainty. However, in the more realistic situation where all models are incorrect or incomplete, the interpretation of model selection outcomes and the role of experimental design needs to be examined more carefully. Using a novel experimental design and model selection framework for stochastic state-space models, we perform high-throughput in-silico analyses on families of gene regulatory cascade models, to show that the selected model can depend on the experiment performed. We observe that experimental design thus makes confidence a criterion for model choice, but that this does not necessarily correlate with a model's predictive power or correctness. Finally, in the special case of linear ordinary differential equation (ODE) models, we explore how wrong a model has to be before it influences the conclusions of a model selection analysis. PMID:24922483

  11. Model selection in systems biology depends on experimental design.

    PubMed

    Silk, Daniel; Kirk, Paul D W; Barnes, Chris P; Toni, Tina; Stumpf, Michael P H

    2014-06-01

    Experimental design attempts to maximise the information available for modelling tasks. An optimal experiment allows the inferred models or parameters to be chosen with the highest expected degree of confidence. If the true system is faithfully reproduced by one of the models, the merit of this approach is clear - we simply wish to identify it and the true parameters with the most certainty. However, in the more realistic situation where all models are incorrect or incomplete, the interpretation of model selection outcomes and the role of experimental design needs to be examined more carefully. Using a novel experimental design and model selection framework for stochastic state-space models, we perform high-throughput in-silico analyses on families of gene regulatory cascade models, to show that the selected model can depend on the experiment performed. We observe that experimental design thus makes confidence a criterion for model choice, but that this does not necessarily correlate with a model's predictive power or correctness. Finally, in the special case of linear ordinary differential equation (ODE) models, we explore how wrong a model has to be before it influences the conclusions of a model selection analysis.

  12. Performance Modeling of Experimental Laser Lightcrafts

    NASA Technical Reports Server (NTRS)

    Wang, Ten-See; Chen, Yen-Sen; Liu, Jiwen; Myrabo, Leik N.; Mead, Franklin B., Jr.; Turner, Jim (Technical Monitor)

    2001-01-01

    A computational plasma aerodynamics model is developed to study the performance of a laser propelled Lightcraft. The computational methodology is based on a time-accurate, three-dimensional, finite-difference, chemically reacting, unstructured grid, pressure-based formulation. The underlying physics are added and tested systematically using a building-block approach. The physics modeled include non-equilibrium thermodynamics, non-equilibrium air-plasma finite-rate kinetics, specular ray tracing, laser beam energy absorption and refraction by plasma, non-equilibrium plasma radiation, and plasma resonance. A series of transient computations are performed at several laser pulse energy levels and the simulated physics are discussed and compared with those of tests and literatures. The predicted coupling coefficients for the Lightcraft compared reasonably well with those of tests conducted on a pendulum apparatus.

  13. Model Comparisons with STELLA Experimental Results

    NASA Astrophysics Data System (ADS)

    Kimura, W. D.; Babzien, M.; Ben-Zvi, I.; Campbell, L. C.; Cline, D. B.; Dilley, C. E.; Gallardo, J. C.; Gottschalk, S. C.; Kusche, K. P.; Pantell, R. H.; Pogorelsky, I. V.; Quimby, D. C.; Skaritka, J.; Steinhauer, L. C.; Yakimenko, V.; Zhou, F.

    2004-12-01

    High-trapping efficiency and narrow energy spread in a staged laser acceleration system was demonstrated during the Staged Electron Laser Acceleration (STELLA) experiment. The experiment used inverse free electron lasers (IFEL) driven by the Brookhaven National Laboratory Accelerator Test Facility (ATF) CO2 laser. The First IFEL modulated the electron beam energy. A subsequent chicane created a train of ˜3 fs-long microbunches separated by 10.6 μm. These microbunches are trapped and accelerated in a second IFEL, where up to 80% trapping efficiencies and energy spreads down to 0.36% (1σ) were measured. This paper presents additional model comparisons with the data, and discusses the strengths and limitations of the model.

  14. Modeling the dynamical systems on experimental data

    NASA Astrophysics Data System (ADS)

    Janson, Natalie B.; Anishchenko, Vadim S.

    1996-06-01

    An attempt is made in the work to create qualitative models of some real biological systems, i.e., isolated frog's heart, a human's heart and a blood circulation system of a white rat. Sampled one-dimensional realizations of these systems were taken as the initial data. Correlation dimensions were calculated to evaluate the embedding dimensions of the systems' attractors. The result of the work are the systems of ordinary differential equations which approximately describe the dynamics of the systems under investigation.

  15. Experimental Validation of a Thermoelastic Model for SMA Hybrid Composites

    NASA Technical Reports Server (NTRS)

    Turner, Travis L.

    2001-01-01

    This study presents results from experimental validation of a recently developed model for predicting the thermomechanical behavior of shape memory alloy hybrid composite (SMAHC) structures, composite structures with an embedded SMA constituent. The model captures the material nonlinearity of the material system with temperature and is capable of modeling constrained, restrained, or free recovery behavior from experimental measurement of fundamental engineering properties. A brief description of the model and analysis procedures is given, followed by an overview of a parallel effort to fabricate and characterize the material system of SMAHC specimens. Static and dynamic experimental configurations for the SMAHC specimens are described and experimental results for thermal post-buckling and random response are presented. Excellent agreement is achieved between the measured and predicted results, fully validating the theoretical model for constrained recovery behavior of SMAHC structures.

  16. Experimental Forelimb Allotransplantation in Canine Model

    PubMed Central

    2016-01-01

    As reconstructive transplantation is gaining popularity as a viable alternative for upper limb amputees, it is becoming increasingly important for plastic surgeons to renew surgical skills and knowledge of this area. Forelimb allotransplantation research has been performed previously in rodent and swine models. However, preclinical canine forelimb allotransplantation studies are lacking in the literature. The purpose of this paper is to provide an overview of the surgical skills necessary to successfully perform forelimb transplantation in canines as a means to prepare for clinical application. A total of 18 transplantation operations on canines were performed. The recipient limb was shortened at the one-third proximal forearm level. The operation was performed in the following order: bones (two reconstructive plates), muscles and tendons (separately sutured), nerves (median, ulnar, and radial nerve), arteries (two), and veins (two). The total mean time of transplantation was 5 hours ± 30 minutes. All of the animals that received transplantation were treated with FK-506 (tacrolimus, 2 mg/kg) for 7 days after surgery. Most allografts survived with perfect viability without vascular problems during the early postoperative period. The canine forelimb allotransplantation model is well qualified to be a suitable training model for standard transplantation and future research work. PMID:27597952

  17. Different experimental approaches in modelling cataractogenesis

    PubMed Central

    Kyselova, Zuzana

    2010-01-01

    Cataract, the opacification of eye lens, is the leading cause of blindness worldwide. At present, the only remedy is surgical removal of the cataractous lens and substitution with a lens made of synthetic polymers. However, besides significant costs of operation and possible complications, an artificial lens just does not have the overall optical qualities of a normal one. Hence it remains a significant public health problem, and biochemical solutions or pharmacological interventions that will maintain the transparency of the lens are highly required. Naturally, there is a persistent demand for suitable biological models. The ocular lens would appear to be an ideal organ for maintaining culture conditions because of lacking blood vessels and nerves. The lens in vivo obtains its nutrients and eliminates waste products via diffusion with the surrounding fluids. Lens opacification observed in vivo can be mimicked in vitro by addition of the cataractogenic agent sodium selenite (Na2SeO3) to the culture medium. Moreover, since an overdose of sodium selenite induces also cataract in young rats, it became an extremely rapid and convenient model of nuclear cataract in vivo. The main focus of this review will be on selenium (Se) and its salt sodium selenite, their toxicological characteristics and safety data in relevance of modelling cataractogenesis, either under in vivo or in vitro conditions. The studies revealing the mechanisms of lens opacification induced by selenite are highlighted, the representatives from screening for potential anti-cataract agents are listed. PMID:21217865

  18. Experimentally testing the standard cosmological model

    SciTech Connect

    Schramm, D.N. Fermi National Accelerator Lab., Batavia, IL )

    1990-11-01

    The standard model of cosmology, the big bang, is now being tested and confirmed to remarkable accuracy. Recent high precision measurements relate to the microwave background; and big bang nucleosynthesis. This paper focuses on the latter since that relates more directly to high energy experiments. In particular, the recent LEP (and SLC) results on the number of neutrinos are discussed as a positive laboratory test of the standard cosmology scenario. Discussion is presented on the improved light element observational data as well as the improved neutron lifetime data. alternate nucleosynthesis scenarios of decaying matter or of quark-hadron induced inhomogeneities are discussed. It is shown that when these scenarios are made to fit the observed abundances accurately, the resulting conclusions on the baryonic density relative to the critical density, {Omega}{sub b}, remain approximately the same as in the standard homogeneous case, thus, adding to the robustness of the standard model conclusion that {Omega}{sub b} {approximately} 0.06. This latter point is the deriving force behind the need for non-baryonic dark matter (assuming {Omega}{sub total} = 1) and the need for dark baryonic matter, since {Omega}{sub visible} < {Omega}{sub b}. Recent accelerator constraints on non-baryonic matter are discussed, showing that any massive cold dark matter candidate must now have a mass M{sub x} {approx gt} 20 GeV and an interaction weaker than the Z{sup 0} coupling to a neutrino. It is also noted that recent hints regarding the solar neutrino experiments coupled with the see-saw model for {nu}-masses may imply that the {nu}{sub {tau}} is a good hot dark matter candidate. 73 refs., 5 figs.

  19. [Deafness and aging: studies in experimental models].

    PubMed

    Gil Loyzaga, Pablo E

    2002-01-01

    Since 1970 a progressive aging of the world population, mainly in the most developed countries, has been observed. Spain could have, around 2050, the most aged human population of the world. Therefore, scientist show an increasing interest on the study of the aging-related pathologies (i.e. deafness linked to aging process: presbycusis). The deep analysis of the presbycusis physiopathology will be based on the study of patients, but also on animal models. This report summarizes our results obtained on the analysis of the deafness linked to aging on the C57/BL/6 mice.

  20. Modeling the dynamical systems on experimental data

    SciTech Connect

    Janson, N.B.; Anishchenko, V.S.

    1996-06-01

    An attempt is made in the work to create qualitative models of some real biological systems, i.e., isolated frog{close_quote}s heart, a human{close_quote}s heart and a blood circulation system of a white rat. Sampled one-dimensional realizations of these systems were taken as the initial data. Correlation dimensions were calculated to evaluate the embedding dimensions of the systems{close_quote} attractors. The result of the work are the systems of ordinary differential equations which approximately describe the dynamics of the systems under investigation. {copyright} {ital 1996 American Institute of Physics.}

  1. Experimental photoallergic contact dermatitis: a mouse model

    SciTech Connect

    Maguire, H.C. Jr.; Kaidbey, K.

    1982-09-01

    We have induced photoallergic contact dermatitis in mice to 3,3',4',5 tetrachlorosalicylanilide (TCSA), chlorpromazine and 6-methylcoumarin. These compounds are known to produce photoallergic contact dermatitis in humans. The photoallergic contact dermatitis reaction in the mouse is immunologically specific viz. mice photosensitized to TCSA react, by photochallenge, to that compound and not to chlorpromazine, and conversely. The reaction requires UVA at both sensitization and challenge. It appears to be T-cell mediated in that it can be passively transferred to syngeneic mice by lymph node cells from actively sensitized mice, the histology of the reactions resembles that of classic allergic contact dermatitis in mice, challenge reactions are seen at 24 but not at 4 hr, and photoallergic contact dermatitis can be induced in B-cell deficient mice. The availability of a mouse model for the study of photo-ACD will facilitate the identification of pertinent control mechanisms and may aid in the management of the disease. It is likely that a bioassay for photoallergens of humans can be based on this mouse model.

  2. Experimental rabbit models of Chlamydia pneumoniae infection.

    PubMed Central

    Moazed, T. C.; Kuo, C.; Patton, D. L.; Grayston, J. T.; Campbell, L. A.

    1996-01-01

    Chlamydia pneumoniae (TWAR), a common cause of acute respiratory disease in humans, has recently been associated with coronary and aortic atherosclerosis. In this study, we evaluated rabbit models of chlamydial infection to investigate the pathogenesis of C. pneumoniae infection. New Zealand White rabbits were inoculated intranasally and intratracheally with C. pneumoniae, strain AR-39, and primary and repeated infection were assessed. After a single inoculation, lung pathology was characterized by a moderate self-resolving interstitial pneumonia with bronchiolitis of 21 days in duration. Chlamydial DNA was detected by polymerase chain reaction (PCR) intermittently in the upper respiratory tract and lung tissue through day 21 postinoculation, spleen tissue at day 14, and peripheral blood mononuclear cells at days 3 and 21. After repeated inoculations, chlamydial DNA was detected by PCR in the upper respiratory tract and lung tissue through day 42. Lung lesions consisted of multifocal interstitial mononuclear cell aggregates that persisted up to day 42. Watanabe heritable hyperlipidemic rabbits were less susceptible to C. pneumoniae infection. After multiple inoculations of Watanabe rabbits, C. pneumoniae was detected by PCR and/or immunocytochemistry until day 21. In conclusion, C. pneumoniae induced a moderate respiratory infection in these rabbit models. Images Figure 1 Figure 2 Figure 3 PMID:8579129

  3. Segmented Polynomial Models in Quasi-Experimental Research.

    ERIC Educational Resources Information Center

    Wasik, John L.

    1981-01-01

    The use of segmented polynomial models is explained. Examples of design matrices of dummy variables are given for the least squares analyses of time series and discontinuity quasi-experimental research designs. Linear combinations of dummy variable vectors appear to provide tests of effects in the two quasi-experimental designs. (Author/BW)

  4. Segmented Polynomial Models in Quasi-Experimental Research.

    ERIC Educational Resources Information Center

    Wasik, John L.

    1981-01-01

    The use of segmented polynomial models is explained. Examples of design matrices of dummy variables are given for the least squares analyses of time series and discontinuity quasi-experimental research designs. Linear combinations of dummy variable vectors appear to provide tests of effects in the two quasi-experimental designs. (Author/BW)

  5. Experimental investigation of a flapping wing model

    NASA Astrophysics Data System (ADS)

    Hubel, Tatjana Y.; Tropea, Cameron

    The main objective of this research study was to investigate the aerodynamic forces of an avian flapping wing model system. The model size and the flow conditions were chosen to approximate the flight of a goose. Direct force measurements, using a three-component balance, and PIV flow field measurements parallel and perpendicular to the oncoming flow, were performed in a wind tunnel at Reynolds numbers between 28,000 and 141,000 (3-15 m/s), throughout a range of reduced frequencies between 0.04 and 0.20. The appropriateness of quasi-steady assumptions used to compare 2D, time-averaged particle image velocimetry (PIV) measurements in the wake with direct force measurements was evaluated. The vertical force coefficient for flapping wings was typically significantly higher than the maximum coefficient of the fixed wing, implying the influence of unsteady effects, such as delayed stall, even at low reduced frequencies. This puts the validity of the quasi-steady assumption into question. The (local) change in circulation over the wing beat cycle and the circulation distribution along the wingspan were obtained from the measurements in the tip and transverse vortex planes. Flow separation could be observed in the distribution of the circulation, and while the circulation derived from the wake measurements failed to agree exactly with the absolute value of the circulation, the change in circulation over the wing beat cycle was in excellent agreement for low and moderate reduced frequencies. The comparison between the PIV measurements in the two perpendicular planes and the direct force balance measurements, show that within certain limitations the wake visualization is a powerful tool to gain insight into force generation and the flow behavior on flapping wings over the wing beat cycle.

  6. Experimental investigation of a flapping wing model

    NASA Astrophysics Data System (ADS)

    Hubel, Tatjana Y.; Tropea, Cameron

    2009-05-01

    The main objective of this research study was to investigate the aerodynamic forces of an avian flapping wing model system. The model size and the flow conditions were chosen to approximate the flight of a goose. Direct force measurements, using a three-component balance, and PIV flow field measurements parallel and perpendicular to the oncoming flow, were performed in a wind tunnel at Reynolds numbers between 28,000 and 141,000 (3-15 m/s), throughout a range of reduced frequencies between 0.04 and 0.20. The appropriateness of quasi-steady assumptions used to compare 2D, time-averaged particle image velocimetry (PIV) measurements in the wake with direct force measurements was evaluated. The vertical force coefficient for flapping wings was typically significantly higher than the maximum coefficient of the fixed wing, implying the influence of unsteady effects, such as delayed stall, even at low reduced frequencies. This puts the validity of the quasi-steady assumption into question. The (local) change in circulation over the wing beat cycle and the circulation distribution along the wingspan were obtained from the measurements in the tip and transverse vortex planes. Flow separation could be observed in the distribution of the circulation, and while the circulation derived from the wake measurements failed to agree exactly with the absolute value of the circulation, the change in circulation over the wing beat cycle was in excellent agreement for low and moderate reduced frequencies. The comparison between the PIV measurements in the two perpendicular planes and the direct force balance measurements, show that within certain limitations the wake visualization is a powerful tool to gain insight into force generation and the flow behavior on flapping wings over the wing beat cycle.

  7. Mathematical Models and the Experimental Analysis of Behavior

    ERIC Educational Resources Information Center

    Mazur, James E.

    2006-01-01

    The use of mathematical models in the experimental analysis of behavior has increased over the years, and they offer several advantages. Mathematical models require theorists to be precise and unambiguous, often allowing comparisons of competing theories that sound similar when stated in words. Sometimes different mathematical models may make…

  8. Mathematical Models and the Experimental Analysis of Behavior

    ERIC Educational Resources Information Center

    Mazur, James E.

    2006-01-01

    The use of mathematical models in the experimental analysis of behavior has increased over the years, and they offer several advantages. Mathematical models require theorists to be precise and unambiguous, often allowing comparisons of competing theories that sound similar when stated in words. Sometimes different mathematical models may make…

  9. Methods of experimentation with models and utilization of results

    NASA Technical Reports Server (NTRS)

    Robert,

    1924-01-01

    The present report treats the subject of testing small models in a wind tunnel and of the methods employed for rendering the results constant, accurate and comparable with one another. Detailed experimental results are given.

  10. Experimental tests of the standard model.

    SciTech Connect

    Nodulman, L.

    1998-11-11

    The title implies an impossibly broad field, as the Standard Model includes the fermion matter states, as well as the forces and fields of SU(3) x SU(2) x U(1). For practical purposes, I will confine myself to electroweak unification, as discussed in the lectures of M. Herrero. Quarks and mixing were discussed in the lectures of R. Aleksan, and leptons and mixing were discussed in the lectures of K. Nakamura. I will essentially assume universality, that is flavor independence, rather than discussing tests of it. I will not pursue tests of QED beyond noting the consistency and precision of measurements of {alpha}{sub EM} in various processes including the Lamb shift, the anomalous magnetic moment (g-2) of the electron, and the quantum Hall effect. The fantastic precision and agreement of these predictions and measurements is something that convinces people that there may be something to this science enterprise. Also impressive is the success of the ''Universal Fermi Interaction'' description of beta decay processes, or in more modern parlance, weak charged current interactions. With one coupling constant G{sub F}, most precisely determined in muon decay, a huge number of nuclear instabilities are described. The slightly slow rate for neutron beta decay was one of the initial pieces of evidence for Cabbibo mixing, now generalized so that all charged current decays of any flavor are covered.

  11. Morphofunctional analysis of experimental model of esophageal achalasia in rats.

    PubMed

    Sabirov, A G; Raginov, I S; Burmistrov, M V; Chelyshev, Y A; Khasanov, R Sh; Moroshek, A A; Grigoriev, P N; Zefirov, A L; Mukhamedyarov, M A

    2010-10-01

    We carried out a detailed analysis of rat model of esophageal achalasia previously developed by us. Manifest morphological and functional disorders were observed in experimental achalasia: hyperplasia of the squamous epithelium, reduced number of nerve fibers, excessive growth of fibrous connective tissue in the esophageal wall, high contractile activity of the lower esophageal sphincter, and reduced motility of the longitudinal muscle layer. Changes in rat esophagus observed in experimental achalasia largely correlate with those in esophageal achalasia in humans. Hence, our experimental model can be used for the development of new methods of disease treatment.

  12. The Standard Solar Model versus Experimental Observations

    NASA Astrophysics Data System (ADS)

    Manuel, O.

    2000-12-01

    The standard solar model (ssm) assumes the that Sun formed as a homogeneous body, its interior consists mostly of hydrogen, and its radiant energy comes from H-fusion in its core. Two sets of measurements indicate the ssm is wrong: 1. Analyses of material in the planetary system show that - (a) Fe, O, Ni, Si, Mg, S and Ca have high nuclear stability and comprise 98+% of ordinary meteorites that formed at the birth of the solar system; (b) the cores of inner planets formed in a central region consisting mostly of heavy elements like Fe, Ni and S; (c) the outer planets formed mostly from elements like H, He and C; and (d) isotopic heterogeneities accompanied these chemical gradients in debris of the supernova that exploded here 5 billion years ago to produce the solar system (See Origin of the Elements at http://www.umr.edu/õm/). 2. Analyses of material coming from the Sun show that - (a) there are not enough neutrinos for H-fusion to be its main source of energy; (b) light-weight isotopes (mass =L) of He, Ne, Ar, Kr and Xe in the solar wind are enriched relative to heavy isotopes (mass = H) by a factor, f, where log f = 4.56 log [H/L] -- - Eq. (1); (c) solar flares by-pass 3.4 of these 9-stages of diffusion and deplete the light-weight isotopes of He, Ne, Mg and Ar by a factor, f*, where log f* = -1.7 log [H/L] --- Eq. (2); (d) proton-capture on N-14 increased N-15 in the solar wind over geologic time; and (e) solar flares dredge up nitrogen with less N-15 from this H-fusion reaction. Each observation above is unexplained by ssm. After correcting photospheric abundances for diffusion [Observation 2(b)], the most abundant elements in the bulk sun are Fe, Ni, O, Si, S, Mg and Ca, the same elements that comprise ordinary meteorites [Observation 1(a)]. The probability that Eq. (1) would randomly select these elements from the photosphere, i.e., the likelihood for a meaningless agreement between observations 2(b) and 1(a), is < 2.0E(-33). Thus, ssm does not describe the

  13. Current Experimental Basis for Modeling Ice Accretions on Swept Wings

    NASA Technical Reports Server (NTRS)

    Vargas, Mario

    2005-01-01

    This work presents a review of the experimental basis for modeling ice accretions on swept wings. Experimental work related to ice accretion physics on swept wings conducted between 1954 and 2004 is reviewed. Proposed models or explanations of scallop formations are singled out and discussed. Special emphasis is placed on reviewing the work done to determine the basic macroscopic mechanisms of scallop formation. The role of feather growth and its connection to scallop growth is discussed. Conceptual steps in modeling scallop formations are presented. Research elements needed for modeling are discussed.

  14. Combined experimental/analytical modeling of shell/payload structures

    SciTech Connect

    Martinez, D.R.; Miller, A.K.; Carne, T.G.

    1985-12-01

    This study evaluates the accuracy of computed modal frequencies obtained from a combined experimental/analytical model of a shell/payload structure. A component mode synthesis technique was used which incorporated free modes and residual effects. The total structure is physically divided into the two subsystems which are connected through stiff joints. The payload was tested to obtain its free-free modes, while a finite element model of the shell was analyzed to obtain its modal description. Both the translational and rotational components of the experimental mode shapes at the payload interface were used in the coupling. Sensitivity studies were also performed to determine the effect of neglecting the residual terms of the payload. Results from a previous study of a combined experimental/analytical model for a beam structure are also given. The beam structure was used to examine the basic procedures and difficulties in experimentally measuring, and analytically accounting for the rotational and residual quantities.

  15. Rabbit as an animal model for experimental research.

    PubMed

    Mapara, Manjeet; Thomas, Betsy Sara; Bhat, K M

    2012-01-01

    Animal experimentation is carried out in consultation with the veterinary wing but it is essential that be familiar with experimental protocols of animal model to be able to design an approriate study. This is more so in place where the veterinary facilities are not easily available.Span Rabbits are commonly used as subjects for screening implant material. They have gained favour for their numerous advantages even though they should be ideally used prior to testing in a larger animal model. Though experimentation on rabbits seems to be easy there are many pitfalls. Our endeavor in this article is to integrate all the data about maintaining rabbits as a model and to critically analyze it on the basis of our experimentation.

  16. Combustion modeling for experimentation in a space environment

    NASA Technical Reports Server (NTRS)

    Berlad, A. L.

    1974-01-01

    The merits of combustion experimentation in a space environment are assessed, and the impact of such experimentation on current theoretical models is considered. It is noted that combustion theory and experimentation for less than normal gravitational conditions are incomplete, inadequate, or nonexistent. Extensive and systematic experimentation in a space environment is viewed as essential for more adequate and complete theoretical models of such processes as premixed flame propagation and extinction limits, premixed flame propagation in droplet and particle clouds, ignition and autoignition in premixed combustible media, and gas jet combustion of unpremixed reactants. Current theories and models in these areas are described, and some combustion studies that can be undertaken in the Space Shuttle Program are proposed, including crossed molecular beam, turbulence, and upper pressure limit (of gases) studies.

  17. Model identification in computational stochastic dynamics using experimental modal data

    NASA Astrophysics Data System (ADS)

    Batou, A.; Soize, C.; Audebert, S.

    2015-01-01

    This paper deals with the identification of a stochastic computational model using experimental eigenfrequencies and mode shapes. In the presence of randomness, it is difficult to construct a one-to-one correspondence between the results provided by the stochastic computational model and the experimental data because of the random modes crossing and veering phenomena that may occur from one realization to another one. In this paper, this correspondence is constructed by introducing an adapted transformation for the computed modal quantities. Then the transformed computed modal quantities can be compared with the experimental data in order to identify the parameters of the stochastic computational model. The methodology is applied to a booster pump of thermal units for which experimental modal data have been measured on several sites.

  18. Optimizing Experimental Design for Comparing Models of Brain Function

    PubMed Central

    Daunizeau, Jean; Preuschoff, Kerstin; Friston, Karl; Stephan, Klaas

    2011-01-01

    This article presents the first attempt to formalize the optimization of experimental design with the aim of comparing models of brain function based on neuroimaging data. We demonstrate our approach in the context of Dynamic Causal Modelling (DCM), which relates experimental manipulations to observed network dynamics (via hidden neuronal states) and provides an inference framework for selecting among candidate models. Here, we show how to optimize the sensitivity of model selection by choosing among experimental designs according to their respective model selection accuracy. Using Bayesian decision theory, we (i) derive the Laplace-Chernoff risk for model selection, (ii) disclose its relationship with classical design optimality criteria and (iii) assess its sensitivity to basic modelling assumptions. We then evaluate the approach when identifying brain networks using DCM. Monte-Carlo simulations and empirical analyses of fMRI data from a simple bimanual motor task in humans serve to demonstrate the relationship between network identification and the optimal experimental design. For example, we show that deciding whether there is a feedback connection requires shorter epoch durations, relative to asking whether there is experimentally induced change in a connection that is known to be present. Finally, we discuss limitations and potential extensions of this work. PMID:22125485

  19. Recent developments in experimental animal models of Henipavirus infection.

    PubMed

    Rockx, Barry

    2014-07-01

    Hendra (HeV) and Nipah (NiV) viruses (genus Henipavirus (HNV; family Paramyxoviridae) are emerging zoonotic agents that can cause severe respiratory distress and acute encephalitis in humans. Given the lack of effective therapeutics and vaccines for human use, these viruses are considered as public health concerns. Several experimental animal models of HNV infection have been developed in recent years. Here, we review the current status of four of the most promising experimental animal models (mice, hamsters, ferrets, and African green monkeys) and their suitability for modeling the clinical disease, transmission, pathogenesis, prevention, and treatment for HNV infection in humans.

  20. Modeling, Robust Control, and Experimental Validation of a Supercavitating Vehicle

    NASA Astrophysics Data System (ADS)

    Escobar Sanabria, David

    This dissertation considers the mathematical modeling, control under uncertainty, and experimental validation of an underwater supercavitating vehicle. By traveling inside a gas cavity, a supercavitating vehicle reduces hydrodynamic drag, increases speed, and minimizes power consumption. The attainable speed and power efficiency make these vehicles attractive for undersea exploration, high-speed transportation, and defense. However, the benefits of traveling inside a cavity come with difficulties in controlling the vehicle dynamics. The main challenge is the nonlinear force that arises when the back-end of the vehicle pierces the cavity. This force, referred to as planing, leads to oscillatory motion and instability. Control technologies that are robust to planing and suited for practical implementation need to be developed. To enable these technologies, a low-order vehicle model that accounts for inaccuracy in the characterization of planing is required. Additionally, an experimental method to evaluate possible pitfalls in the models and controllers is necessary before undersea testing. The major contribution of this dissertation is a unified framework for mathematical modeling, robust control synthesis, and experimental validation of a supercavitating vehicle. First, we introduce affordable experimental methods for mathematical modeling and controller testing under planing and realistic flow conditions. Then, using experimental observations and physical principles, we create a low-order nonlinear model of the longitudinal vehicle motion. This model quantifies the planing uncertainty and is suitable for robust controller synthesis. Next, based on the vehicle model, we develop automated tools for synthesizing controllers that deliver a certificate of performance in the face of nonlinear and uncertain planing forces. We demonstrate theoretically and experimentally that the proposed controllers ensure higher performance when the uncertain planing dynamics are

  1. Using an experimental model for the study of therapeutic touch.

    PubMed

    dos Santos, Daniella Soares; Marta, Ilda Estéfani Ribeiro; Cárnio, Evelin Capellari; de Quadros, Andreza Urba; Cunha, Thiago Mattar; de Carvalho, Emilia Campos

    2013-02-01

    to verify whether the Paw Edema Model can be used in investigations about the effects of Therapeutic Touch on inflammation by measuring the variables pain, edema and neutrophil migration. this is a pilot and experimental study, involving ten male mice of the same genetic strain and divided into experimental and control group, submitted to the chemical induction of local inflammation in the right back paw. The experimental group received a daily administration of Therapeutic Touch for 15 minutes during three days. the data showed statistically significant differences in the nociceptive threshold and in the paw circumference of the animals from the experimental group on the second day of the experiment. the experiment model involving animals can contribute to study the effects of Therapeutic Touch on inflammation, and adjustments are suggested in the treatment duration, number of sessions and experiment duration.

  2. Computational modeling of epilepsy for an experimental neurologist

    PubMed Central

    Holt, Abbey B.; Netoff, Theoden I.

    2013-01-01

    Computational modeling can be a powerful tool for an experimentalist, providing a rigorous mathematical model of the system you are studying. This can be valuable in testing your hypotheses and developing experimental protocols prior to experimenting. This paper reviews models of seizures and epilepsy at different scales, including cellular, network, cortical region, and brain scales by looking at how they have been used in conjunction with experimental data. At each scale, models with different levels of abstraction, the extraction of physiological detail, are presented. Varying levels of detail are necessary in different situations. Physiologically realistic models are valuable surrogates for experimental systems because, unlike in an experiment, every parameter can be changed and every variable can be observed. Abstract models are useful in determining essential parameters of a system, allowing the experimentalist to extract principles that explain the relationship between mechanisms and the behavior of the system. Modeling is becoming easier with the emergence of platforms dedicated to neuronal modeling and databases of models that can be downloaded. Modeling will never be a replacement for animal and clinical experiments, but it should be a starting point in designing experiments and understanding their results. PMID:22617489

  3. An experimentally determined evolutionary model dramatically improves phylogenetic fit.

    PubMed

    Bloom, Jesse D

    2014-08-01

    All modern approaches to molecular phylogenetics require a quantitative model for how genes evolve. Unfortunately, existing evolutionary models do not realistically represent the site-heterogeneous selection that governs actual sequence change. Attempts to remedy this problem have involved augmenting these models with a burgeoning number of free parameters. Here, I demonstrate an alternative: Experimental determination of a parameter-free evolutionary model via mutagenesis, functional selection, and deep sequencing. Using this strategy, I create an evolutionary model for influenza nucleoprotein that describes the gene phylogeny far better than existing models with dozens or even hundreds of free parameters. Emerging high-throughput experimental strategies such as the one employed here provide fundamentally new information that has the potential to transform the sensitivity of phylogenetic and genetic analyses.

  4. Experimental Modeling of a Formula Student Carbon Composite Nose Cone.

    PubMed

    Fellows, Neil A

    2017-06-06

    A numerical impact study is presented on a Formula Student (FS) racing car carbon composite nose cone. The effect of material model and model parameter selection on the numerical deceleration curves is discussed in light of the experimental deceleration data. The models show reasonable correlation in terms of the shape of the deceleration-displacement curves but do not match the peak deceleration values with errors greater that 30%.

  5. Nonequilibrium stage modelling of dividing wall columns and experimental validation

    NASA Astrophysics Data System (ADS)

    Hiller, Christoph; Buck, Christina; Ehlers, Christoph; Fieg, Georg

    2010-11-01

    Dealing with complex process units like dividing wall columns pushes the focus on the determination of suitable modelling approaches. For this purpose a nonequilibrium stage model is developed. The successful validation is achieved by an experimental investigation of fatty alcohol mixtures under vacuum condition at pilot scale. Aim is the recovery of high purity products. The proposed model predicts the product qualities and temperature profiles very well.

  6. Experimental Models of Transfusion-Related Acute Lung Injury (TRALI)

    PubMed Central

    Gilliss, Brian M.; Looney, Mark R.

    2010-01-01

    Transfusion-related acute lung injury (TRALI) is defined clinically as acute lung injury occurring within six hours of the transfusion of any blood product. It is the leading cause of transfusion-related death in the United States, but under-recognition and diagnostic uncertainty have limited clinical research to smaller case control studies. In this review we will discuss the contribution of experimental models to the understanding of TRALI pathophysiology and potential therapeutic approaches. Experimental models suggest that TRALI occurs when a host, with a primed immune system, is exposed to an activating agent such as anti-leukocyte antibody or a biologic response modifier such as lysophosphatidylcholines. Recent work has suggested a critical role for platelets in antibody-based experimental models and identified potential therapeutic strategies for TRALI. PMID:21134622

  7. A systematic review of animal models for experimental neuroma.

    PubMed

    Toia, Francesca; Giesen, Thomas; Giovanoli, Pietro; Calcagni, Maurizio

    2015-10-01

    Peripheral neuromas can result in an unbearable neuropathic pain and functional impairment. Their treatment is still challenging, and their optimal management is to be defined. Experimental research still plays a major role, but - although numerous neuroma models have been proposed on different animals - there is still no single model recognised as being the reference. Several models show advantages over the others in specific aspects of neuroma physiopathology, prevention or treatment, making it unlikely that a single model could be of reference. A reproducible and standardised model of peripheral neuroma would allow better comparison of results from different studies. We present a systematic review of the literature on experimental in vivo models, analysing advantages and disadvantages, specific features and indications, with the goal of providing suggestions to help their standardisation. Published models greatly differ in the animal and the nerve employed, the mechanisms of nerve injury and the evaluation methods. Specific experimental models exist for terminal neuromas and neuromas in continuity (NIC). The rat is the most widely employed animal, the rabbit being the second most popular model. NIC models are more actively researched, but it is more difficult to generate such studies in a reproducible manner. Nerve transection is considered the best method to cause terminal neuromas, whereas partial transection is the best method to cause NIC. Traditional histomorphology is the historical gold-standard evaluation method, but immunolabelling, reverse transcriptase-polymerase chain reaction (RT-PCR) and proteomics are gaining increasing popularity. Computerised gait analysis is the gold standard for motor-recovery evaluation, whereas mechanical testing of allodynia and hyperalgesia reproducibly assesses sensory recovery. This review summarises current knowledge on experimental neuroma models, and it provides a useful tool for defining experimental protocols

  8. 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

  9. Experimental validation of flexible robot arm modeling and control

    NASA Technical Reports Server (NTRS)

    Ulsoy, A. Galip

    1989-01-01

    Flexibility is important for high speed, high precision operation of lightweight manipulators. Accurate dynamic modeling of flexible robot arms is needed. Previous work has mostly been based on linear elasticity with prescribed rigid body motions (i.e., no effect of flexible motion on rigid body motion). Little or no experimental validation of dynamic models for flexible arms is available. Experimental results are also limited for flexible arm control. Researchers include the effects of prismatic as well as revolute joints. They investigate the effect of full coupling between the rigid and flexible motions, and of axial shortening, and consider the control of flexible arms using only additional sensors.

  10. Integrating the glioblastoma microenvironment into engineered experimental models

    PubMed Central

    Xiao, Weikun; Sohrabi, Alireza; Seidlits, Stephanie K

    2017-01-01

    Glioblastoma (GBM) is the most lethal cancer originating in the brain. Its high mortality rate has been attributed to therapeutic resistance and rapid, diffuse invasion – both of which are strongly influenced by the unique microenvironment. Thus, there is a need to develop new models that mimic individual microenvironmental features and are able to provide clinically relevant data. Current understanding of the effects of the microenvironment on GBM progression, established experimental models of GBM and recent developments using bioengineered microenvironments as ex vivo experimental platforms that mimic the biochemical and physical properties of GBM tumors are discussed. PMID:28883992

  11. Optimality models in the age of experimental evolution and genomics

    PubMed Central

    Bull, J. J.; Wang, I.-N.

    2010-01-01

    Optimality models have been used to predict evolution of many properties of organisms. They typically neglect genetic details, whether by necessity or design. This omission is a common source of criticism, and although this limitation of optimality is widely acknowledged, it has mostly been defended rather than evaluated for its impact. Experimental adaptation of model organisms provides a new arena for testing optimality models and for simultaneously integrating genetics. First, an experimental context with a well-researched organism allows dissection of the evolutionary process to identify causes of model failure – whether the model is wrong about genetics or selection. Second, optimality models provide a meaningful context for the process and mechanics of evolution, and thus may be used to elicit realistic genetic bases of adaptation – an especially useful augmentation to well-researched genetic systems. A few studies of microbes have begun to pioneer this new direction. Incompatibility between the assumed and actual genetics has been demonstrated to be the cause of model failure in some cases. More interestingly, evolution at the phenotypic level has sometimes matched prediction even though the adaptive mutations defy mechanisms established by decades of classic genetic studies. Integration of experimental evolutionary tests with genetics heralds a new wave for optimality models and their extensions that does not merely emphasize the forces driving evolution. PMID:20646132

  12. Experimental porcine model of complex fistula-in-ano

    PubMed Central

    A Ba-Bai-Ke-Re, Ma-Mu-Ti-Jiang; Chen, Hui; Liu, Xue; Wang, Yun-Hai

    2017-01-01

    AIM To establish and evaluate an experimental porcine model of fistula-in-ano. METHODS Twelve healthy pigs were randomly divided into two groups. Under general anesthesia, the experimental group underwent rubber band ligation surgery, and the control group underwent an artificial damage technique. Clinical magnetic resonance imaging (MRI) and histopathological evaluation were performed on the 38th d and 48th d after surgery in both groups, respectively. RESULTS There were no significant differences between the experimental group and the control group in general characteristics such as body weight, gender, and the number of fistula (P > 0.05). In the experimental group, 15 fistulas were confirmed clinically, 13 complex fistulas were confirmed by MRI, and 11 complex fistulas were confirmed by histopathology. The success rate in the porcine complex fistula model establishment was 83.33%. Among the 18 fistulas in the control group, 5 fistulas were confirmed clinically, 4 complex fistulas were confirmed by MRI, and 3 fistulas were confirmed by histopathology. The success rate in the porcine fistula model establishment was 27.78%. Thus, the success rate of the rubber band ligation group was significantly higher than the control group (P < 0.05). CONCLUSION Rubber band ligation is a stable and reliable method to establish complex fistula-in-ano models. Large animal models of complex anal fistulas can be used for the diagnosis and treatment of anal fistulas. PMID:28348488

  13. Multilevel statistical models and the analysis of experimental data.

    PubMed

    Behm, Jocelyn E; Edmonds, Devin A; Harmon, Jason P; Ives, Anthony R

    2013-07-01

    Data sets from ecological experiments can be difficult to analyze, due to lack of independence of experimental units and complex variance structures. In addition, information of interest may lie in complicated contrasts among treatments, rather than direct output from statistical tests. Here, we present a statistical framework for analyzing data sets containing non-independent experimental units and differences in variance among treatments (heteroscedasticity) and apply this framework to experimental data on interspecific competition among three tadpole species. Our framework involves three steps: (1) use a multilevel regression model to calculate coefficients of treatment effects on response variables; (2) combine coefficients to quantify the strength of competition (the target information of our experiment); and (3) use parametric bootstrapping to calculate significance of competition strengths. We repeated this framework using three multilevel regression models to analyze data at the level of individual tadpoles, at the replicate level, and at the replicate level accounting for heteroscedasticity. Comparing results shows the need to correctly specify the statistical model, with the model that accurately accounts for heteroscedasticity leading to different conclusions from the other two models. This approach gives a single, comprehensive analysis of experimental data that can be used to extract informative biological parameters in a statistically rigorous way.

  14. Team Modelling: Review of Experimental Scenarios and Computational Models

    DTIC Science & Technology

    2006-09-01

    designed to be) Yes Yes No Yes (Model individuals, or sub-teams - groups of individuals.) 19 C3TRACE* (Command, Control, and Communicatio ...radar sensors, satellites, c2 structures, jammers, communicatio ns networks and devices, and fire support) Depends (EADSIM normally models at...researchers and corporations around the world. Soar has been under development for over 20 years and has been used in major military

  15. [Instrumental and ethical aspects of experimental research with animal models].

    PubMed

    Watanabe, Mirian; da Fonseca, Cassiane Dezoti; Vattimo, Maria de Fatima Fernandes

    2014-02-01

    Experimental animal models offer possibilities of physiology knowledge, pathogenesis of disease and action of drugs that are directly related to quality nursing care. This integrative review describes the current state of the instrumental and ethical aspects of experimental research with animal models, including the main recommendations of ethics committees that focus on animal welfare and raises questions about the impact of their findings in nursing care. Data show that, in Brazil, the progress in ethics for the use of animals for scientific purposes was consolidated with Law No. 11.794/2008 establishing ethical procedures, attending health, genetic and experimental parameters. The application of ethics in handling of animals for scientific and educational purposes and obtaining consistent and quality data brings unquestionable contributions to the nurse, as they offer subsidies to relate pathophysiological mechanisms and the clinical aspect on the patient.

  16. Experimental models of renal disease and the cardiovascular system.

    PubMed

    Grossman, Rebecca C

    2010-11-26

    Cardiovascular disease is a leading cause of death among patients with end stage renal failure. Animal models have played a crucial role in teasing apart the complex pathological processes involved. This review discusses the principles of using animal models, the history of their use in the study of renal hypertension, the controversies arising from experimental models of non-hypertensive uraemic cardiomyopathy and the lessons learned from these models, and highlights important areas of future research in this field, including de novo cardiomyopathy secondary to renal transplantation.

  17. A numerical cloud model for the support of laboratory experimentation

    NASA Technical Reports Server (NTRS)

    Hagen, D. E.

    1979-01-01

    A numerical cloud model is presented which can describe the evolution of a cloud starting from moist aerosol-laden air through the diffusional growth regime. The model is designed for the direct support of cloud chamber laboratory experimentation, i.e., experiment preparation, real-time control and data analysis. In the model the thermodynamics is uncoupled from the droplet growth processes. Analytic solutions for the cloud droplet growth equations are developed which can be applied in most laboratory situations. The model is applied to a variety of representative experiments.

  18. Experimental bounds on collapse models from gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    Carlesso, Matteo; Bassi, Angelo; Falferi, Paolo; Vinante, Andrea

    2016-12-01

    Wave function collapse models postulate a fundamental breakdown of the quantum superposition principle at the macroscale. Therefore, experimental tests of collapse models are also fundamental tests of quantum mechanics. Here, we compute the upper bounds on the collapse parameters, which can be inferred by the gravitational wave detectors LIGO, LISA Pathfinder, and AURIGA. We consider the most widely used collapse model, the continuous spontaneous localization (CSL) model. We show that these experiments exclude a huge portion of the CSL parameter space, the strongest bound being set by the recently launched space mission LISA Pathfinder. We also rule out a proposal for quantum-gravity-induced decoherence.

  19. Microbiome and Asthma: What Have Experimental Models Already Taught Us?

    PubMed Central

    Bonamichi-Santos, R.; Aun, M. V.; Agondi, R. C.; Kalil, J.; Giavina-Bianchi, P.

    2015-01-01

    Asthma is a chronic inflammatory disease that imposes a substantial burden on patients, their families, and the community. Although many aspects of the pathogenesis of classical allergic asthma are well known by the scientific community, other points are not yet understood. Experimental asthma models, particularly murine models, have been used for over 100 years in order to better understand the immunopathology of asthma. It has been shown that human microbiome is an important component in the development of the immune system. Furthermore, the occurrence of many inflammatory diseases is influenced by the presence of microbes. Again, experimental models of asthma have helped researchers to understand the relationship between the microbiome and respiratory inflammation. In this review, we discuss the evolution of murine models of asthma and approach the major studies involving the microbiome and asthma. PMID:26266269

  20. Seismo-acoustic ray model benchmarking against experimental tank data.

    PubMed

    Camargo Rodríguez, Orlando; Collis, Jon M; Simpson, Harry J; Ey, Emanuel; Schneiderwind, Joseph; Felisberto, Paulo

    2012-08-01

    Acoustic predictions of the recently developed traceo ray model, which accounts for bottom shear properties, are benchmarked against tank experimental data from the EPEE-1 and EPEE-2 (Elastic Parabolic Equation Experiment) experiments. Both experiments are representative of signal propagation in a Pekeris-like shallow-water waveguide over a non-flat isotropic elastic bottom, where significant interaction of the signal with the bottom can be expected. The benchmarks show, in particular, that the ray model can be as accurate as a parabolic approximation model benchmarked in similar conditions. The results of benchmarking are important, on one side, as a preliminary experimental validation of the model and, on the other side, demonstrates the reliability of the ray approach for seismo-acoustic applications.

  1. Numerical and experimental verification of physical blast thermodynamic model

    NASA Astrophysics Data System (ADS)

    Chorowski, Maciej; Iluk, Artur; Grabowski, Maciej; Jędrusyna, Artur

    2015-12-01

    Helium inventory in big cryogenic systems may be of the order of hundred tons. During the warm up of the machine the helium has to be stored in warm pressurized tanks. A potential rupture of the tank may create a danger to adjacent objects. In order to formulate recommendations concerning storage of compressed gases in close vicinity of nuclear installations, a thermodynamic model of physical blast has been formulated. The model has been experimentally verified in a laboratory scale test rig. To simulate rupture of compressed gas storage tanks, plastic tanks have been used. Scaling of the results to real cases like ITER compressed gas inventory requires good understanding of potential rupture of high volume gas storage tanks. Numerical model of tanks rupture have been elaborated and verified against experimental results. The model allows scaling of thermodynamic simplified description to real gas storage installations.

  2. Developing an Experimental Model of Vascular Toxicity in Embryonic Zebrafish

    EPA Science Inventory

    Developing an Experimental Model of Vascular Toxicity in Embryonic Zebrafish Tamara Tal, Integrated Systems Toxicology Division, U.S. EPA Background: There are tens of thousands of chemicals that have yet to be fully evaluated for their toxicity by validated in vivo testing ...

  3. Experimental validation of a solar-chimney power plant model

    NASA Astrophysics Data System (ADS)

    Fathi, Nima; Wayne, Patrick; Trueba Monje, Ignacio; Vorobieff, Peter

    2016-11-01

    In a solar chimney power plant system (SCPPS), the energy of buoyant hot air is converted to electrical energy. SCPPS includes a collector at ground level covered with a transparent roof. Solar radiation heats the air inside and the ground underneath. There is a tall chimney at the center of the collector, and a turbine located at the base of the chimney. Lack of detailed experimental data for validation is one of the important issues in modeling this type of power plants. We present a small-scale experimental prototype developed to perform validation analysis for modeling and simulation of SCCPS. Detailed velocity measurements are acquired using particle image velocimetry (PIV) at a prescribed Reynolds number. Convection is driven by a temperature-controlled hot plate at the bottom of the prototype. Velocity field data are used to perform validation analysis and measure any mismatch of the experimental results and the CFD data. CFD Code verification is also performed, to assess the uncertainly of the numerical model with respect to our grid and the applied mathematical model. The dimensionless output power of the prototype is calculated and compared with a recent analytical solution and the experimental results.

  4. Computational Modeling and Experimental Facts of Mixed Self- Assembly Systems.

    PubMed

    Messina, Paula V; Besada-Porto, Jose Miguel; Rial, Ramón; González-Díaz, Humberto; Ruso, Juan M

    2016-01-01

    The formation of liposomes, nanoparticle micelles, and related systems by mixtures of drugs and/or surfactants is of major relevance for the design of drug delivery systems. We can design new systems using different compounds. Traditionally these systems are created by trial and error using experimental data. However, in most cases measuring all the possible combinations represents a extensive work and almost always unaffordable. In this sense, we can use theoretical concepts and develop computational models to predict different physicochemical properties of self-aggregation processes of mixed molecular systems. In a previous work, we developed a new PT-LFER model (Linear Free Energy Relationships, LFER, combined with Perturbation Theory, PT, ideas) for binary systems. The best PT-LFER model found predicted the effects of 25000 perturbations over nine different properties of binary systems. The present work has two parts. Firstly, we carry out an analysis on the new results on the applications and experimental-theoretical studies of binary selfassembled systems. In the second part, we report for the first time, a new experimental-theoretic study of the NaDC-DTAB binary system. For this purpose, we have combined experimental procedures plus physicochemical thermodynamic framework with the PT-LFER model reported in our previous work.

  5. An Experimental Model for the Study of Infectious Otitis Externa.

    DTIC Science & Technology

    Through study of five small laboratory animals the guinea pig was found to be a useful experimental model for the study of otitis externa . Infection...and in disease. Data presented suggests that the presence of a normal bacterial flora is of significance in reducing the incidence of otitis externa ...aeruginosa. The data supports the concept of a multiplex etiology of otitis externa . (Author)

  6. Developing an Experimental Model of Vascular Toxicity in Embryonic Zebrafish

    EPA Science Inventory

    Developing an Experimental Model of Vascular Toxicity in Embryonic Zebrafish Tamara Tal, Integrated Systems Toxicology Division, U.S. EPA Background: There are tens of thousands of chemicals that have yet to be fully evaluated for their toxicity by validated in vivo testing ...

  7. Experimental Models of Ocular Infection with Toxoplasma Gondii

    PubMed Central

    Dukaczewska, Agata; Tedesco, Roberto; Liesenfeld, Oliver

    2015-01-01

    Ocular toxoplasmosis is a vision-threatening disease and the major cause of posterior uveitis worldwide. In spite of the continuing global burden of ocular toxoplasmosis, many critical aspects of disease including the therapeutic approach to ocular toxoplasmosis are still under debate. To assist in addressing many aspects of the disease, numerous experimental models of ocular toxoplasmosis have been established. In this article, we present an overview on in vitro, ex vivo, and in vivo models of ocular toxoplasmosis available to date. Experimental studies on ocular toxoplasmosis have recently focused on mice. However, the majority of murine models established so far are based on intraperitoneal and intraocular infection with Toxoplasma gondii. We therefore also present results obtained in an in vivo model using peroral infection of C57BL/6 and NMRI mice that reflects the natural route of infection and mimics the disease course in humans. While advances have been made in ex vivo model systems or larger animals to investigate specific aspects of ocular toxoplasmosis, laboratory mice continue to be the experimental model of choice for the investigation of ocular toxoplasmosis. PMID:26716018

  8. Experimental Models of Ocular Infection with Toxoplasma Gondii.

    PubMed

    Dukaczewska, Agata; Tedesco, Roberto; Liesenfeld, Oliver

    2015-12-01

    Ocular toxoplasmosis is a vision-threatening disease and the major cause of posterior uveitis worldwide. In spite of the continuing global burden of ocular toxoplasmosis, many critical aspects of disease including the therapeutic approach to ocular toxoplasmosis are still under debate. To assist in addressing many aspects of the disease, numerous experimental models of ocular toxoplasmosis have been established. In this article, we present an overview on in vitro, ex vivo, and in vivo models of ocular toxoplasmosis available to date. Experimental studies on ocular toxoplasmosis have recently focused on mice. However, the majority of murine models established so far are based on intraperitoneal and intraocular infection with Toxoplasma gondii. We therefore also present results obtained in an in vivo model using peroral infection of C57BL/6 and NMRI mice that reflects the natural route of infection and mimics the disease course in humans. While advances have been made in ex vivo model systems or larger animals to investigate specific aspects of ocular toxoplasmosis, laboratory mice continue to be the experimental model of choice for the investigation of ocular toxoplasmosis.

  9. Impact of model defect and experimental uncertainties on evaluated output

    NASA Astrophysics Data System (ADS)

    Neudecker, D.; Capote, R.; Leeb, H.

    2013-09-01

    One of the current major problems in nuclear data evaluation is the unreasonably small evaluated uncertainties often obtained. These small uncertainties are partly attributed to missing correlations of experimental uncertainties as well as to deficiencies of the model employed for the prior information. In this article, both uncertainty sources are included in an evaluation of 55Mn cross-sections for incident neutrons. Their impact on the evaluated output is studied using a prior obtained by the Full Bayesian Evaluation Technique and a prior obtained by the nuclear model program EMPIRE. It is shown analytically and by means of an evaluation that unreasonably small evaluated uncertainties can be obtained not only if correlated systematic uncertainties of the experiment are neglected but also if prior uncertainties are smaller or about the same magnitude as the experimental ones. Furthermore, it is shown that including model defect uncertainties in the evaluation of 55Mn leads to larger evaluated uncertainties for channels where the model is deficient. It is concluded that including correlated experimental uncertainties is equally important as model defect uncertainties, if the model calculations deviate significantly from the measurements.

  10. Experimental verification of a pendant ice formation model

    SciTech Connect

    Szilder, K.; Forest, T.; Lozowski, E.P.

    1995-12-31

    A random walk model has been developed to predict the growth of pendant ice formations and icicles. The model allows an efficient representation of water flow along the surface, dripping from lower extremities, and freezing of water. Using a simple analysis, the microscopic model parameters are expressed as functions of the macroscopic physical conditions. To verify the random walk model, a series of laboratory experiments was conducted in an icing wind tunnel. A horizontal thin wire was exposed to vertically falling supercooled spray and the formation of icicles underneath the wire was examined. Model verification based on a comparison with the experimental results demonstrates quantitatively and qualitatively the credibility and value of this model approach. Future model development will involve the quantitative simulation of ice accretion on objects of complex geometry, such as offshore structures, ships, and transmission lines.

  11. Systematic integration of experimental data and models in systems biology

    PubMed Central

    2010-01-01

    Background The behaviour of biological systems can be deduced from their mathematical models. However, multiple sources of data in diverse forms are required in the construction of a model in order to define its components and their biochemical reactions, and corresponding parameters. Automating the assembly and use of systems biology models is dependent upon data integration processes involving the interoperation of data and analytical resources. Results Taverna workflows have been developed for the automated assembly of quantitative parameterised metabolic networks in the Systems Biology Markup Language (SBML). A SBML model is built in a systematic fashion by the workflows which starts with the construction of a qualitative network using data from a MIRIAM-compliant genome-scale model of yeast metabolism. This is followed by parameterisation of the SBML model with experimental data from two repositories, the SABIO-RK enzyme kinetics database and a database of quantitative experimental results. The models are then calibrated and simulated in workflows that call out to COPASIWS, the web service interface to the COPASI software application for analysing biochemical networks. These systems biology workflows were evaluated for their ability to construct a parameterised model of yeast glycolysis. Conclusions Distributed information about metabolic reactions that have been described to MIRIAM standards enables the automated assembly of quantitative systems biology models of metabolic networks based on user-defined criteria. Such data integration processes can be implemented as Taverna workflows to provide a rapid overview of the components and their relationships within a biochemical system. PMID:21114840

  12. Theories linguistiques, modeles informatiques, experimentation psycholinguistique (Linguistic Theories, Information-Processing Models, Psycholinguistic Experimentation)

    ERIC Educational Resources Information Center

    Dubois, Daniele

    1975-01-01

    Delineates and elaborates upon the underlying psychological postulates in linguistic and information-processing models, and shows the interdependence of psycholinguistics and linguistic analysis. (Text is in French.) (DB)

  13. Theories linguistiques, modeles informatiques, experimentation psycholinguistique (Linguistic Theories, Information-Processing Models, Psycholinguistic Experimentation)

    ERIC Educational Resources Information Center

    Dubois, Daniele

    1975-01-01

    Delineates and elaborates upon the underlying psychological postulates in linguistic and information-processing models, and shows the interdependence of psycholinguistics and linguistic analysis. (Text is in French.) (DB)

  14. Embryonated chicken eggs: An experimental model for Pythium insidiosum infection.

    PubMed

    Verdi, Camila M; Jesus, Francielli P K; Kommers, Glaucia; Ledur, Pauline C; Azevedo, Maria I; Loreto, Erico S; Tondolo, Juliana S M; Andrade, Eduardo N C; Schlemmer, Karine B; Alves, Sydney H; Santurio, Janio M

    2017-10-03

    Pythiosis is a severe disease caused by Pythium insidiosum. Currently, the research on the treatment of pythiosis uses rabbits as an experimental infection model. To reduce the use of animals in scientific experimentation, alternative models are increasingly necessary options. The objective of this study was to establish a new experimental infection model for pythiosis using embryonated chicken eggs. First, we tested the inoculation of 4 zoospore concentrations into the egg allantoic cavity at 3 embryonic days. We observed that increased zoospore concentration causes a decrease in survival time, and at a later embryonic day (the 14th) of infection, embryos showed delayed mortality. To confirm the reproducibility of the model, we chose the 14th embryonic day for the inoculation of 50 zoospores/egg, and the experiment was repeated twice. Mortality began with 30% embryos 48 hours after inoculation, and 95% embryos died within 72 hours. There was no mortality in the uninfected control group. The infection was confirmed by culture, PCR and histopathology. Immunohistochemistry confirmed the presence of hyphae in blood vessels in the umbilical cords in 95% of embryos and only 1 liver (5%). Our results suggest that embryonated eggs can be a very useful alternative infection model to study pythiosis. © 2017 Blackwell Verlag GmbH.

  15. Optimization of Regression Models of Experimental Data Using Confirmation Points

    NASA Technical Reports Server (NTRS)

    Ulbrich, N.

    2010-01-01

    A new search metric is discussed that may be used to better assess the predictive capability of different math term combinations during the optimization of a regression model of experimental data. The new search metric can be determined for each tested math term combination if the given experimental data set is split into two subsets. The first subset consists of data points that are only used to determine the coefficients of the regression model. The second subset consists of confirmation points that are exclusively used to test the regression model. The new search metric value is assigned after comparing two values that describe the quality of the fit of each subset. The first value is the standard deviation of the PRESS residuals of the data points. The second value is the standard deviation of the response residuals of the confirmation points. The greater of the two values is used as the new search metric value. This choice guarantees that both standard deviations are always less or equal to the value that is used during the optimization. Experimental data from the calibration of a wind tunnel strain-gage balance is used to illustrate the application of the new search metric. The new search metric ultimately generates an optimized regression model that was already tested at regression model independent confirmation points before it is ever used to predict an unknown response from a set of regressors.

  16. Drilling forces model for lunar regolith exploration and experimental validation

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Ding, Xilun

    2017-02-01

    China's Chang'e lunar exploration project aims to sample and return lunar regolith samples at a minimum penetration depth of 2 m in 2017. Unlike such tasks on the Earth, automated drilling and sampling missions on the Moon are more complicated. Therefore, a delicately designed drill tool is required to minimize operational cost and enhance reliability. Penetration force and rotational torque are two critical parameters in designing the drill tool. In this paper, a novel numerical model for predicting penetration force and rotational torque in the drilling of lunar regolith is proposed. The model is based on quasi-static Mohr-Coulomb soil mechanics and explicitly describes the interaction between drill tool and lunar regolith. Geometric features of drill tool, mechanical properties of lunar regolith, and drilling parameters are taken into consideration in the model. Consequently, a drilling test bed was developed, and experimental penetration force and rotational torque were obtained in penetrating a lunar regolith simulant with different drilling parameters. Finally, theoretical and experimental results were compared to validate the proposed model. Experimental results indicated that the numerical model had good accuracy and was effective in predicting the penetration force and rotational torque in drilling the lunar regolith simulant.

  17. Multiscale Modeling of Gastrointestinal Electrophysiology and Experimental Validation

    PubMed Central

    Du, Peng; O'Grady, Greg; Davidson, John B.; Cheng, Leo K.; Pullan, Andrew J.

    2011-01-01

    Normal gastrointestinal (GI) motility results from the coordinated interplay of multiple cooperating mechanisms, both intrinsic and extrinsic to the GI tract. A fundamental component of this activity is an omnipresent electrical activity termed slow waves, which is generated and propagated by the interstitial cells of Cajal (ICCs). The role of ICC loss and network degradation in GI motility disorders is a significant area of ongoing research. This review examines recent progress in the multiscale modeling framework for effectively integrating a vast range of experimental data in GI electrophysiology, and outlines the prospect of how modeling can provide new insights into GI function in health and disease. The review begins with an overview of the GI tract and its electrophysiology, and then focuses on recent work on modeling GI electrical activity, spanning from cell to body biophysical scales. Mathematical cell models of the ICCs and smooth muscle cell are presented. The continuum framework of monodomain and bidomain models for tissue and organ models are then considered, and the forward techniques used to model the resultant body surface potential and magnetic field are discussed. The review then outlines recent progress in experimental support and validation of modeling, and concludes with a discussion on potential future research directions in this field. PMID:21133835

  18. Regression Model Optimization for the Analysis of Experimental Data

    NASA Technical Reports Server (NTRS)

    Ulbrich, N.

    2009-01-01

    A candidate math model search algorithm was developed at Ames Research Center that determines a recommended math model for the multivariate regression analysis of experimental data. The search algorithm is applicable to classical regression analysis problems as well as wind tunnel strain gage balance calibration analysis applications. The algorithm compares the predictive capability of different regression models using the standard deviation of the PRESS residuals of the responses as a search metric. This search metric is minimized during the search. Singular value decomposition is used during the search to reject math models that lead to a singular solution of the regression analysis problem. Two threshold dependent constraints are also applied. The first constraint rejects math models with insignificant terms. The second constraint rejects math models with near-linear dependencies between terms. The math term hierarchy rule may also be applied as an optional constraint during or after the candidate math model search. The final term selection of the recommended math model depends on the regressor and response values of the data set, the user s function class combination choice, the user s constraint selections, and the result of the search metric minimization. A frequently used regression analysis example from the literature is used to illustrate the application of the search algorithm to experimental data.

  19. Heterogeneity in Pure Microbial Systems: Experimental Measurements and Modeling

    PubMed Central

    González-Cabaleiro, Rebeca; Mitchell, Anca M.; Smith, Wendy; Wipat, Anil; Ofiţeru, Irina D.

    2017-01-01

    Cellular heterogeneity influences bioprocess performance in ways that until date are not completely elucidated. In order to account for this phenomenon in the design and operation of bioprocesses, reliable analytical and mathematical descriptions are required. We present an overview of the single cell analysis, and the mathematical modeling frameworks that have potential to be used in bioprocess control and optimization, in particular for microbial processes. In order to be suitable for bioprocess monitoring, experimental methods need to be high throughput and to require relatively short processing time. One such method used successfully under dynamic conditions is flow cytometry. Population balance and individual based models are suitable modeling options, the latter one having in particular a good potential to integrate the various data collected through experimentation. This will be highly beneficial for appropriate process design and scale up as a more rigorous approach may prevent a priori unwanted performance losses. It will also help progressing synthetic biology applications to industrial scale. PMID:28970826

  20. Experimental, statistical, and biological models of radon carcinogenesis

    SciTech Connect

    Cross, F.T.

    1991-09-01

    Risk models developed for underground miners have not been consistently validated in studies of populations exposed to indoor radon. Imprecision in risk estimates results principally from differences between exposures in mines as compared to domestic environments and from uncertainties about the interaction between cigarette-smoking and exposure to radon decay products. Uncertainties in extrapolating miner data to domestic exposures can be reduced by means of a broad-based health effects research program that addresses the interrelated issues of exposure, respiratory tract dose, carcinogenesis (molecular/cellular and animal studies, plus developing biological and statistical models), and the relationship of radon to smoking and other copollutant exposures. This article reviews experimental animal data on radon carcinogenesis observed primarily in rats at Pacific Northwest Laboratory. Recent experimental and mechanistic carcinogenesis models of exposures to radon, uranium ore dust, and cigarette smoke are presented with statistical analyses of animal data. 20 refs., 1 fig.

  1. Experimental Validation of a Pulse Tube Cfd Model

    NASA Astrophysics Data System (ADS)

    Taylor, R. P.; Nellis, G. F.; Klein, S. A.; Radebaugh, R.; Lewis, M.; Bradley, P.

    2010-04-01

    Computational fluid dynamic (CFD) analysis has been applied by various authors to study the processes occurring in the pulse tube cryocooler and carry out parametric design and optimization. However, a thorough and quantitative validation of the CFD model predications against experimental data has not been accomplished. This is in part due to the difficulty associated with measuring the specific quantities of interest (e.g., internal enthalpy flows and acoustic power) rather than generic system performance (e.g., cooling power). This paper presents the experimental validation of a previously published two-dimensional, axisymmetric CFD model of the pulse tube and its associated flow transitions. The test facility designed for this purpose is unique in that it allows the precise measurement of the cold end acoustic power, regenerator loss, and cooling power. Therefore, it allows the separate and precise measurement of both the pulse tube loss and the regenerator loss. The experimental results are presented for various pulse tube and flow transition configurations operating at a cold end temperature of 80 K over a range of pressure ratios. The comparison of the model prediction to the experimental data is presented with discussion.

  2. Damping formulas and experimental values of damping in flutter models

    NASA Technical Reports Server (NTRS)

    Coleman, Robert P

    1940-01-01

    The problem of determining values of structural damping for use in flutter calculations is discussed. The concept of equivalent viscous damping is reviewed and its relation to the structural damping coefficient g introduced in NACA Technical Report No. 685 is shown. The theory of normal modes is reviewed and a number of methods are described for separating the motions associated with different modes. Equations are developed for use in evaluating the damping parameters from experimental data. Experimental results of measurements of damping in several flutter models are presented.

  3. Icing simulation: A survey of computer models and experimental facilities

    NASA Technical Reports Server (NTRS)

    Potapczuk, M. G.; Reinmann, J. J.

    1991-01-01

    A survey of the current methods for simulation of the response of an aircraft or aircraft subsystem to an icing encounter is presented. The topics discussed include a computer code modeling of aircraft icing and performance degradation, an evaluation of experimental facility simulation capabilities, and ice protection system evaluation tests in simulated icing conditions. Current research focussed on upgrading simulation fidelity of both experimental and computational methods is discussed. The need for increased understanding of the physical processes governing ice accretion, ice shedding, and iced airfoil aerodynamics is examined.

  4. Hosting infection: experimental models to assay Candida virulence.

    PubMed

    Maccallum, Donna M

    2012-01-01

    Although normally commensals in humans, Candida albicans, Candida tropicalis, Candida parapsilosis, Candida glabrata, and Candida krusei are capable of causing opportunistic infections in individuals with altered physiological and/or immunological responses. These fungal species are linked with a variety of infections, including oral, vaginal, gastrointestinal, and systemic infections, with C. albicans the major cause of infection. To assess the ability of different Candida species and strains to cause infection and disease requires the use of experimental infection models. This paper discusses the mucosal and systemic models of infection available to assay Candida virulence and gives examples of some of the knowledge that has been gained to date from these models.

  5. Experimental Evaluation of Equivalent-Fluid Models for Melamine Foam

    NASA Technical Reports Server (NTRS)

    Allen, Albert R.; Schiller, Noah H.

    2016-01-01

    Melamine foam is a soft porous material commonly used in noise control applications. Many models exist to represent porous materials at various levels of fidelity. This work focuses on rigid frame equivalent fluid models, which represent the foam as a fluid with a complex speed of sound and density. There are several empirical models available to determine these frequency dependent parameters based on an estimate of the material flow resistivity. Alternatively, these properties can be experimentally educed using an impedance tube setup. Since vibroacoustic models are generally sensitive to these properties, this paper assesses the accuracy of several empirical models relative to impedance tube measurements collected with melamine foam samples. Diffuse field sound absorption measurements collected using large test articles in a laboratory are also compared with absorption predictions determined using model-based and measured foam properties. Melamine foam slabs of various thicknesses are considered.

  6. Experimental evolution of viruses: Microviridae as a model system

    PubMed Central

    Wichman, Holly A.; Brown, Celeste J.

    2010-01-01

    φX174 was developed as a model system for experimental studies of evolution because of its small genome size and ease of cultivation. It has been used extensively to address statistical questions about the dynamics of adaptive evolution. Molecular changes seen during experimental evolution of φX174 under a variety of conditions were compiled from 10 experiments comprising 58 lineages, where whole genomes were sequenced. A total of 667 substitutions was seen. Parallel evolution was rampant, with over 50 per cent of substitutions occurring at sites with three or more events. Comparisons of experimentally evolved sites to variation seen among wild phage suggest that at least some of the adaptive mechanisms seen in the laboratory are relevant to adaptation in nature. Elucidation of these mechanisms is aided by the availability of capsid and pro-capsid structures for φX174 and builds on years of genetic studies of the phage life history. PMID:20643739

  7. Experimental and mathematical modeling of flow in headboxes

    NASA Astrophysics Data System (ADS)

    Shariati, Mohammad Reza

    The fluid flow patterns in a paper-machine headbox have a strong influence on the quality of the paper produced by the machine. Due to increasing demand for high quality paper there is a need to investigate the details of the fluid flow in the paper machine headbox. The objective of this thesis is to use experimental and computational methods of modeling the flow inside a typical headbox in order to evaluate and understand the mean flow patterns and turbulence created there. In particular, spatial variations of the mean flow and of the turbulence quantities and the turbulence generated secondary flows are studied. In addition to the flow inside the headbox, the flow leaving the slice is also modeled both experimentally and computationally. Comparison of the experimental and numerical results indicated that streamwise mean components of the velocities in the headbox are predicted well by all the turbulence models considered in this study. However, the standard k-epsilon model and the algebraic turbulence models fail to predict the turbulence quantities accurately. Standard k-epsilon-model also fails to predict the direction and magnitude of the secondary flows. Significant improvements in the k-epsilon model predictions were achieved when the turbulence production term was artificially set to zero. This is justified by observations of the turbulent velocities from the experiments and by a consideration of the form of the kinetic energy equation. A better estimation of the Reynolds normal stress distribution and the degree of anisotropy of turbulence was achieved using the Reynolds stress turbulence model. Careful examination of the measured turbulence velocity results shows that after the initial decay of the turbulence in the headbox, there is a short region close to the exit, but inside the headbox, where the turbulent kinetic energy actually increases as a result of the distortion imposed by the contraction. The turbulence energy quickly resumes its decay in the

  8. Recapitulating Human Gastric Cancer Pathogenesis: Experimental Models of Gastric Cancer.

    PubMed

    Ding, Lin; El Zaatari, Mohamad; Merchant, Juanita L

    2016-01-01

    This review focuses on the various experimental models to study gastric cancer pathogenesis, with the role of genetically engineered mouse models (GEMMs) used as the major examples. We review differences in human stomach anatomy compared to the stomachs of the experimental models, including the mouse and invertebrate models such as Drosophila and C. elegans. The contribution of major signaling pathways, e.g., Notch, Hedgehog, AKT/PI3K is discussed in the context of their potential contribution to foregut tumorigenesis. We critically examine the rationale behind specific GEMMs, chemical carcinogens, dietary promoters, Helicobacter infection, and direct mutagenesis of relevant oncogenes and tumor suppressor that have been developed to study gastric cancer pathogenesis. Despite species differences, more efficient and effective models to test specific genes and pathways disrupted in human gastric carcinogenesis have yet to emerge. As we better understand these species differences, "humanized" versions of mouse models will more closely approximate human gastric cancer pathogenesis. Towards that end, epigenetic marks on chromatin, the gut microbiota, and ways of manipulating the immune system will likely move center stage, permitting greater overlap between rodent and human cancer phenotypes thus providing a unified progression model.

  9. Modeling and experimental result analysis for high-power VECSELs

    NASA Astrophysics Data System (ADS)

    Zakharian, Aramais R.; Hader, Joerg; Moloney, Jerome V.; Koch, Stephan W.; Lutgen, Stephan; Brick, Peter; Albrecht, Tony; Grotsch, Stefan; Luft, Johann; Spath, Werner

    2003-06-01

    We present a comparison of experimental and microscopically based model results for optically pumped vertical external cavity surface emitting semiconductor lasers. The quantum well gain model is based on a quantitative ab-initio approach that allows calculation of a complex material susceptibility dependence on the wavelength, carrier density and lattice temperature. The gain model is coupled to the macroscopic thermal transport, spatially resolved in both the radial and longitudinal directions, with temperature and carrier density dependent pump absorption. The radial distribution of the refractive index and gain due to temperature variation are computed. Thermal managment issues, highlighted by the experimental data, are discussed. Experimental results indicate a critical dependence of the input power, at which thermal roll-over occurs, on the thermal resistance of the device. This requires minimization of the substrate thickness and optimization of the design and placement of the heatsink. Dependence of the model results on the radiative and non-radiative carrier recombination lifetimes and cavity losses are evaluated.

  10. SHEEP AS AN EXPERIMENTAL MODEL FOR BIOMATERIAL IMPLANT EVALUATION

    PubMed Central

    SARTORETTO, SUELEN CRISTINA; UZEDA, MARCELO JOSÉ; MIGUEL, FÚLVIO BORGES; NASCIMENTO, JHONATHAN RAPHAELL; ASCOLI, FABIO; CALASANS-MAIA, MÔNICA DIUANA

    2016-01-01

    ABSTRACT Objective: Based on a literature review and on our own experience, this study proposes sheep as an experimental model to evaluate the bioactive capacity of bone substitute biomaterials, dental implant systems and orthopedics devices. The literature review covered relevant databases available on the Internet from 1990 until to date, and was supplemented by our own experience. Methods: For its resemblance in size and weight to humans, sheep are quite suitable for use as an experimental model. However, information about their utility as an experimental model is limited. The different stages involving sheep experiments were discussed, including the care during breeding and maintenance of the animals obtaining specimens for laboratory processing, and highlighting the unnecessary euthanasia of animals at the end of study, in accordance to the guidelines of the 3Rs Program. Results: All experiments have been completed without any complications regarding the animals and allowed us to evaluate hypotheses and explain their mechanisms. Conclusion: The sheep is an excellent animal model for evaluation of biomaterial for bone regeneration and dental implant osseointegration. From an ethical point of view, one sheep allows for up to 12 implants per animal, permitting to keep them alive at the end of the experiments. Level of Evidence II, Retrospective Study. PMID:28149193

  11. Transvaginal ultrasound ovarian diathermy: sheep as an experimental model

    PubMed Central

    2012-01-01

    Background Some techniques of transvaginal ovarian drilling have been previously described. Nevertheless a monopolar transvaginal ovarian cauterization, that use the expertise and safety of transvaginal puncture for oocyte captation seems to be an easier and feasible approach. The aim of this study was to develop a minimally invasive ovarian cauterization technique under transvaginal ultrasound control, and to evaluate the safety of the transvaginal ovarian monopolar cauterization, female sheep at reproductive age were used as an experimental model. Findings An experimental study was performed in a university research center. Seventeen female sheep (15 Corriedale e 2 Suffolk) in reproductive age were submitted to transvaginal ovarian cauterization with a monopolar Valleylab Force 2 electrocautery. Macroscopic and microscopic lesions were assessed. Ovarian size were 1.31 cm2 ± 0,43 (Corriedale) and 3.41 cm2 ± 0,64 (Suffolk). From 30 ovaries from Corriedale sheep punctured, only 3 were cauterized, presenting macroscopic and typical microscopic lesion. In the Suffolk sheep group, only one ovary was cauterized. No lesion could be found in the needle path. Conclusions This is the first experimental animal model described for ovarian cauterization needle guided by transvaginal ultrasound. The sheep does not seem to be the ideal animal model to study this technique. Another animal model, whose ovaries are better identified by transvaginal ultrasound should be sought for this technique, theoretically less invasive, before it could be offered safely to women with polycystic ovary syndrome. PMID:22243998

  12. Renal vascular responses in an experimental model of preeclampsia.

    PubMed

    Bobadilla Lugo, Rosa Amalia; Pérez-Alvarez, Víctor M; Robledo, Liliana Anguiano; López Sanchez, Pedro

    2005-01-01

    In pregnancy there is an attenuated response to vasoconstrictors and pressor agents, including Angiotensin II (Ang II). This effect is reverted in preeclampsia. We evaluated the renal pressor response induced by Ang II in an experimental model of preeclampsia based on the development of feto-placental ischemia produced by a subrenal aortic coarctation (SRAC). Dose-response curves for Ang II were obtained in an isolated perfused kidney preparation comparing groups of SRAC pregnant and non-pregnant rats in the presence and absence of losartan (AT1 antagonist) or PD123319 (AT2 antagonist). Kidneys from the experimental model of pre-eclampsia showed an enhanced response to AngII. In addition, losartan (10 nM) inhibited the vasopressor effect to Ang II in this model but not in the control group. PD 123319 (1 nM), increased the response in both groups, but the effect was more evident in the pre-eclamptic group. This suggests modifications in the relative participation of renal vascular receptors AT1/AT2 induced by an experimental model of pre-eclampsia, with an increased participation of AT1 and a decreased participation of AT2.

  13. Ionospheric topside models compared with experimental electron density profiles

    NASA Astrophysics Data System (ADS)

    Coisson, P.; Radicella, S. M.

    2003-04-01

    In the last couple of years an increasing number of topside electron density profiles has been made available through the Internet to the scientific community. This kind of data is particularly important for ionospheric modeling purposes, since the experimental information on the electron density above the ionosphere maximum of ionization is very scarce. The present work analyses the behavior of the NeQuick and IRI models, adopted by the ITU-R recommendation P.531-5, with respect to the topside electron density profiles available in the databases of ISIS2, IK19 and Cosmos-1809 satellites. Experimental total electron content (TEC) from the F2 peak up to satellite height and electron densities at fixed heights above that peak have been compared with values computed with the models. A wide range of different conditions (solar activity, local time, geographical and geomagnetic position has been considered). The analysis done allows to point out the behavior of the models and the improvement needed to allow a better reproduction of the experimental results.

  14. Experimental animal data and modeling of late somatic effects

    SciTech Connect

    Fry, R.J.M.

    1988-01-01

    This section is restricted to radiation-induced life shortening and cancer and mainly to studies with external radiation. The emphasis will be on the experimental data that are available and the experimental systems that could provide the type of data with which to either formulate or test models. Genetic effects which are of concern are not discussed in this section. Experimental animal radiation studies fall into those that establish general principles and those that demonstrate mechanisms. General principles include the influence of dose, radiation quality, dose rate, fractionation, protraction and such biological factors as age and gender. The influence of these factors are considered as general principles because they are independent, at least qualitatively, of the species studied. For example, if an increase in the LET of the radiation causes an increased effectiveness in cancer induction in a mouse a comparable increase in effectiveness can be expected in humans. Thus, models, whether empirical or mechanistic, formulated from experimental animal data should be generally applicable.

  15. Numerical modeling of experimental human fibrous cap delamination.

    PubMed

    Leng, Xiaochang; Davis, Lindsey A; Deng, Xiaomin; Sutton, Michael A; Lessner, Susan M

    2016-06-01

    Fibrous cap delamination is a critical process during the rupture of atherosclerotic plaque, which often leads to severe life-threatening clinical consequences such as myocardial infarction or stroke. In this study a finite element modeling and simulation approach is presented that enables the study of fibrous cap delamination experiments for the purpose of understanding the fibrous cap delamination process. A cohesive zone model (CZM) approach is applied to simulate delamination of the fibrous cap from the underlying plaque tissue. A viscoelastic anisotropic (VA) model for the bulk arterial material behavior is extended from existing studies so that the hysteresis phenomenon observed in the fibrous cap delamination experiments can be captured. A finite element model is developed for the fibrous cap delamination experiments, in which arterial layers (including the fibrous cap and the underlying plaque tissue) are represented by solid elements based on the VA model and the fibrous cap-underlying plaque tissue interface is characterized by interfacial CZM elements. In the CZM, the delamination process is governed by an exponential traction-separation law which utilizes critical energy release rates obtained directly from the fibrous cap delamination experiments. A set of VA model parameter values and CZM parameter values is determined based on values suggested in the literature and through matching simulation predictions of the load vs. load-point displacement curve with one set of experimental measurements. Using this set of parameter values, simulation predictions for other sets of experimental measurements are obtained and good agreement between simulation predictions and experimental measurements is observed. Results of this study demonstrate the applicability of the viscoelastic anisotropic model and the CZM approach for the simulation of diseased arterial tissue failure processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Predictions of Cockpit Simulator Experimental Outcome Using System Models

    NASA Technical Reports Server (NTRS)

    Sorensen, J. A.; Goka, T.

    1984-01-01

    This study involved predicting the outcome of a cockpit simulator experiment where pilots used cockpit displays of traffic information (CDTI) to establish and maintain in-trail spacing behind a lead aircraft during approach. The experiments were run on the NASA Ames Research Center multicab cockpit simulator facility. Prior to the experiments, a mathematical model of the pilot/aircraft/CDTI flight system was developed which included relative in-trail and vertical dynamics between aircraft in the approach string. This model was used to construct a digital simulation of the string dynamics including response to initial position errors. The model was then used to predict the outcome of the in-trail following cockpit simulator experiments. Outcome included performance and sensitivity to different separation criteria. The experimental results were then used to evaluate the model and its prediction accuracy. Lessons learned in this modeling and prediction study are noted.

  17. Experimental support for a model of birdsong production.

    PubMed

    Mindlin, G B; Gardner, T J; Goller, F; Suthers, R

    2003-10-01

    In this work we present an experimental validation of a recently proposed model for the production of birdsongs. We have previously observed that driving the model with simple functions of time, which represent tensions in vocal muscles, produces a wide variety of sounds resembling birdsongs. In this work we drive the model with functions whose time dependence comes from recordings of muscle activities and air sac pressure. We simultaneously recorded the birds' songs and compared them with the synthetic songs. The model produces recognizable songs. Beyond finding a qualitative agreement, we also test some predictions of the model concerning the relative levels of activity in the gating muscles at the beginning and end of a syllable.

  18. Experimental support for a model of birdsong production

    NASA Astrophysics Data System (ADS)

    Mindlin, G. B.; Gardner, T. J.; Goller, F.; Suthers, R.

    2003-10-01

    In this work we present an experimental validation of a recently proposed model for the production of birdsongs. We have previously observed that driving the model with simple functions of time, which represent tensions in vocal muscles, produces a wide variety of sounds resembling birdsongs. In this work we drive the model with functions whose time dependence comes from recordings of muscle activities and air sac pressure. We simultaneously recorded the birds’ songs and compared them with the synthetic songs. The model produces recognizable songs. Beyond finding a qualitative agreement, we also test some predictions of the model concerning the relative levels of activity in the gating muscles at the beginning and end of a syllable.

  19. Understanding the limits to generalizability of experimental evolutionary models.

    PubMed

    Forde, Samantha E; Beardmore, Robert E; Gudelj, Ivana; Arkin, Sinan S; Thompson, John N; Hurst, Laurence D

    2008-09-11

    Given the difficulty of testing evolutionary and ecological theory in situ, in vitro model systems are attractive alternatives; however, can we appraise whether an experimental result is particular to the in vitro model, and, if so, characterize the systems likely to behave differently and understand why? Here we examine these issues using the relationship between phenotypic diversity and resource input in the T7-Escherichia coli co-evolving system as a case history. We establish a mathematical model of this interaction, framed as one instance of a super-class of host-parasite co-evolutionary models, and show that it captures experimental results. By tuning this model, we then ask how diversity as a function of resource input could behave for alternative co-evolving partners (for example, E. coli with lambda bacteriophages). In contrast to populations lacking bacteriophages, variation in diversity with differences in resources is always found for co-evolving populations, supporting the geographic mosaic theory of co-evolution. The form of this variation is not, however, universal. Details of infectivity are pivotal: in T7-E. coli with a modified gene-for-gene interaction, diversity is low at high resource input, whereas, for matching-allele interactions, maximal diversity is found at high resource input. A combination of in vitro systems and appropriately configured mathematical models is an effective means to isolate results particular to the in vitro system, to characterize systems likely to behave differently and to understand the biology underpinning those alternatives.

  20. Target Soil Impact Verification: Experimental Testing and Kayenta Constitutive Modeling.

    SciTech Connect

    Broome, Scott Thomas; Flint, Gregory Mark; Dewers, Thomas; Newell, Pania

    2015-11-01

    This report details experimental testing and constitutive modeling of sandy soil deformation under quasi - static conditions. This is driven by the need to understand constitutive response of soil to target/component behavior upon impact . An experimental and constitutive modeling program was followed to determine elastic - plastic properties and a compressional failure envelope of dry soil . One hydrostatic, one unconfined compressive stress (UCS), nine axisymmetric compression (ACS) , and one uniaxial strain (US) test were conducted at room temperature . Elastic moduli, assuming isotropy, are determined from unload/reload loops and final unloading for all tests pre - failure and increase monotonically with mean stress. Very little modulus degradation was discernable from elastic results even when exposed to mean stresses above 200 MPa . The failure envelope and initial yield surface were determined from peak stresses and observed onset of plastic yielding from all test results. Soil elasto - plastic behavior is described using the Brannon et al. (2009) Kayenta constitutive model. As a validation exercise, the ACS - parameterized Kayenta model is used to predict response of the soil material under uniaxial strain loading. The resulting parameterized and validated Kayenta model is of high quality and suitable for modeling sandy soil deformation under a range of conditions, including that for impact prediction.

  1. Spectral Analysis and Experimental Modeling of Ice Accretion Roughness

    NASA Technical Reports Server (NTRS)

    Orr, D. J.; Breuer, K. S.; Torres, B. E.; Hansman, R. J., Jr.

    1996-01-01

    A self-consistent scheme for relating wind tunnel ice accretion roughness to the resulting enhancement of heat transfer is described. First, a spectral technique of quantitative analysis of early ice roughness images is reviewed. The image processing scheme uses a spectral estimation technique (SET) which extracts physically descriptive parameters by comparing scan lines from the experimentally-obtained accretion images to a prescribed test function. Analysis using this technique for both streamwise and spanwise directions of data from the NASA Lewis Icing Research Tunnel (IRT) are presented. An experimental technique is then presented for constructing physical roughness models suitable for wind tunnel testing that match the SET parameters extracted from the IRT images. The icing castings and modeled roughness are tested for enhancement of boundary layer heat transfer using infrared techniques in a "dry" wind tunnel.

  2. Microelectronics package design using experimentally-validated modeling and simulation.

    SciTech Connect

    Johnson, Jay Dean; Young, Nathan Paul; Ewsuk, Kevin Gregory

    2010-11-01

    Packaging high power radio frequency integrated circuits (RFICs) in low temperature cofired ceramic (LTCC) presents many challenges. Within the constraints of LTCC fabrication, the design must provide the usual electrical isolation and interconnections required to package the IC, with additional consideration given to RF isolation and thermal management. While iterative design and prototyping is an option for developing RFIC packaging, it would be expensive and most likely unsuccessful due to the complexity of the problem. To facilitate and optimize package design, thermal and mechanical simulations were used to understand and control the critical parameters in LTCC package design. The models were validated through comparisons to experimental results. This paper summarizes an experimentally-validated modeling approach to RFIC package design, and presents some results and key findings.

  3. Neutrophils: critical components in experimental animal models of cancer

    PubMed Central

    Hagerling, Catharina; Werb, Zena

    2016-01-01

    Neutrophils have a crucial role in tumor development and metastatic progression. The contribution of neutrophils in tumor development is multifaceted and contradictory. On the one hand, neutrophils prompt tumor inception, promote tumor development by mediating the initial angiogenic switch and facilitate colonization of circulating tumor cells, and on the other hand, have cytotoxic and anti-metastatic capabilities. Our understanding of the role of neutrophils in tumor development has greatly depended on different experimental animal models of cancer. In this review we cover important findings that have been made about neutrophils in experimental animal models of cancer, point to their advantages and limitations, and discuss novel techniques that can be used to expand our knowledge of how neutrophils influence tumor progression. PMID:26976824

  4. Constitutive Model Calibration via Autonomous Multiaxial Experimentation (Postprint)

    DTIC Science & Technology

    2016-09-17

    replace experimental tests to avoid the costs associated with elaborate test fixtures and equipment or expensive physical specimens. In addition...certain stress states commonly of interest are difficult, if not impossible, to physically reproduce in experiments. Accurate material models that are...force and torque capabilities of 100 kN and 1100 N m, respectively. The test frame was controlled using a custom program written in MTS TestSuite. Axial

  5. Experimental model of cutaneous radiation injury in rabbits.

    PubMed

    Meirelles, Rafael Panisi de Campos; Hochman, Bernardo; Helene Junior, Americo; Lellis, Rute; Fraga, Murillo Francisco Pires; Ferreira, Lydia Masako

    2013-11-01

    To describe an experimental model of cutaneous radiation injury in rabbits. On this study eight six-month-old New Zealand male rabbits, with an average weight of 2.5 kg were used. They were distributed in four groups (n=2 per group). The control group did not receive radiotherapy and the others received one radiotherapy session of 2000, 3000 and 4500 cGy, respectively. Photographic analysis and histopathological evaluation of the irradiated areas were carried out. After 30 days, the animals from the control group had all their hair grown. In spite of that, the animals from group 2000 cGy had a 60-day alopecia and from group 3000 cGy, a 90-day alopecia. After the 30th day, the 3000 cGy group demonstrated 90-day cutaneous radiation injuries, graded 3 and 4. One of the animals from group 4500 cGy died on the 7th day with visceral necrosis. The other from the same group had total skin necrosis. A progressive reduction of glands and blood vessels count and an increase on collagen deposition was observed. The proposed experimental model is reproductable. This study suggests that the dosage 4500 cGy is excessive and the 3000 cGy is the most effective for this experimental model of cutaneous radiation injury in rabbits.

  6. Amplified energy harvester from footsteps: design, modeling, and experimental analysis

    NASA Astrophysics Data System (ADS)

    Wang, Ya; Chen, Wusi; Guzman, Plinio; Zuo, Lei

    2014-04-01

    This paper presents the design, modeling and experimental analysis of an amplified footstep energy harvester. With the unique design of amplified piezoelectric stack harvester the kinetic energy generated by footsteps can be effectively captured and converted into usable DC power that could potentially be used to power many electric devices, such as smart phones, sensors, monitoring cameras, etc. This doormat-like energy harvester can be used in crowded places such as train stations, malls, concerts, airport escalator/elevator/stairs entrances, or anywhere large group of people walk. The harvested energy provides an alternative renewable green power to replace power requirement from grids, which run on highly polluting and global-warming-inducing fossil fuels. In this paper, two modeling approaches are compared to calculate power output. The first method is derived from the single degree of freedom (SDOF) constitutive equations, and then a correction factor is applied onto the resulting electromechanically coupled equations of motion. The second approach is to derive the coupled equations of motion with Hamilton's principle and the constitutive equations, and then formulate it with the finite element method (FEM). Experimental testing results are presented to validate modeling approaches. Simulation results from both approaches agree very well with experimental results where percentage errors are 2.09% for FEM and 4.31% for SDOF.

  7. Experimental model of heterotopic ossification in Wistar rats

    PubMed Central

    Zotz, T.G.G.; de Paula, J.B.; Moser, A.D.L.

    2012-01-01

    Heterotopic ossification (HO) is a metaplastic biological process in which there is newly formed bone in soft tissues adjacent to large joints, resulting in joint mobility deficit. In order to determine which treatment techniques are more appropriate for such condition, experimental models of induced heterotopic bone formation have been proposed using heterologous demineralized bone matrix implants and bone morphogenetic protein and other tissues. The objective of the present experimental study was to identify a reliable protocol to induce HO in Wistar rats, based on autologous bone marrow (BM) implantation, comparing 3 different BM volumes and based on literature evidence of this HO induction model in larger laboratory animals. Twelve male Wistar albino rats weighing 350/390 g were used. The animals were anesthetized for blood sampling before HO induction in order to quantify serum alkaline phosphatase (ALP). HO was induced by BM implantation in both quadriceps muscles of these animals, experimental group (EG). Thirty-five days after the induction, another blood sample was collected for ALP determination. The results showed a weight gain in the EG and no significant difference in ALP levels when comparing the periods before and after induction. Qualitative histological analysis confirmed the occurrence of heterotopic ossification in all 12 EG rats. In conclusion, the HO induction model was effective when 0.35 mL autologous BM was applied to the quadriceps of Wistar rats. PMID:22473322

  8. A novel experimental model for the study and evaluation of experimental vaccines to Actinobacillus pleuropneumoniae.

    PubMed

    Montaraz, J A; Rosales, M E; Bautista, E; Barcenas, G; Lara, V

    1994-06-01

    A novel experimental model to study immune protection to Actinobacillus pleuropneumoniae in the rat is described. One-week-old rats born from immunized mothers were challenged intraperitoneally with a suspension of A. pleuropneumoniae serotype 1 and mortality recorded up to 48 h postinfection. Immunization with inactivated whole cells (IWC) or a whole cell extract (WCE) from A. pleuropneumoniae serotype 1 resulted in protection against an homologous challenge, particularly in the case of WCE where protection was observed at the highest challenge dose of approximately 1000 50% lethal doses.

  9. CFD modeling of pharmaceutical isolators with experimental verification of airflow.

    PubMed

    Nayan, N; Akay, H U; Walsh, M R; Bell, W V; Troyer, G L; Dukes, R E; Mohan, P

    2007-01-01

    Computational fluid dynamics (CFD) models have been developed to predict the airflow in a transfer isolator using a commercial CFD code. In order to assess the ability of the CFD approach in predicting the flow inside an isolator, hot wire anemometry measurements and a novel experimental flow visualization technique consisting of helium-filled glycerin bubbles were used. The results obtained have been shown to agree well with the experiments and show that CFD can be used to model barrier systems and isolators with practical fidelity. This indicates that CFD can and should be used to support the design, testing, and operation of barrier systems and isolators.

  10. Experimental support for KrF laser modeling. Final report

    SciTech Connect

    Not Available

    1989-07-19

    This paper is the final report for a project to do characterization studies on the KrF laser system. The project did experimental work on KrF lasers in support of modeling studies, with the objective being to see if this technology could be competitive for use in the ICF program. This program has provided LANL with data critical for their model development. Section 2 describes the laser extraction experiments together with the calibration of the diagnostics and the re-examination of the analysis procedure. Section 3 discusses the gain and transient absorption measurements, and Section 4 gives the conclusion for this program.

  11. A simple experimental realization of the Sakaguchi-Kuramoto model

    NASA Astrophysics Data System (ADS)

    Mertens, David; Zeng, Zhuwei; English, Lars

    We explore the collective phase dynamics of Wien-bridge oscillators coupled resistively. The dynamics of these oscillators were recently shown to follow Sakaguchi's modification to the Kuramoto model. In this talk we outline the steps of that analysis. We then examine results for a variety of experimentally obtained coupling arrangements, including all-to-all and some-to-all. In particular, we provide evidence for the emergence of synchronized clusters, a finite-size effect that is not accounted for in the traditional theories for the Sakaguchi-Kuramoto model.

  12. Finite element modeling and experimentation of bone drilling forces

    NASA Astrophysics Data System (ADS)

    Lughmani, W. A.; Bouazza-Marouf, K.; Ashcroft, I.

    2013-07-01

    Bone drilling is an essential part of many orthopaedic surgery procedures, including those for internal fixation and for attaching prosthetics. Estimation and control of bone drilling forces are critical to prevent drill breakthrough, excessive heat generation, and mechanical damage to the bone. This paper presents a 3D finite element (FE) model for prediction of thrust forces experienced during bone drilling. The model incorporates the dynamic characteristics involved in the process along with the accurate geometrical considerations. The average critical thrust forces and torques obtained using FE analysis, for set of machining parameters are found to be in good agreement with the experimental results.

  13. Survey of Experimental Tests of the IBA Model

    SciTech Connect

    Casten, R. F.

    1980-01-01

    A survey of experimental tests of the Interacting Boson Approximation (IBA) Model is presented covering even and odd mass nuclei in the region from A ≈ 80 to A ≈ 230. Both positive and negative parity states with both high and low spin are discussed. Topics included concern energy levels, electromagnetic transition rates, two nucleon transfer and inelastic scattering. Special attention is given to nuclear symmetries and transitional regions. Comparison with other models is made where appropriate. The distinction between IBA-1 and IBA-2 is discussed including their respective areas of applicability.

  14. Model free control for differential pneumatic pistons: experimental comparison

    NASA Astrophysics Data System (ADS)

    Weist, Jens; Arteaga, Marco A.; de la Cruz, Leonardo R.; Hebisch, Holger

    2011-01-01

    PID controllers are widely used in industry. While this may be appropriate for many systems, eventually a more complex or reliable algorithm has to be designed to improve performance. Common praxis is to take advantage either of physical properties (e.g. passivity) or of a mathematical model. For this last case it may prove to be hard to get an accurate description of the system dynamics. In this article we experimentally analyse the behaviour of pneumatic actuators by employing control algorithms available in the literature with little or no model information at all, including an adaptation of a robot control law which is shown to work very well for the test bed.

  15. Experimental investigation on single person's jumping load model

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Wang, Haoqi; Wang, Ling

    2015-12-01

    This paper presents a modified half-sine-squared load model of the jumping impulses for a single person. The model is based on a database of 22,921 experimentally measured single jumping load cycles from 100 test subjects. Threedimensional motion capture technology in conjunction with force plates was employed in the experiment to record jumping loads. The variation range and probability distribution of the controlling parameters for the load model such as the impact factor, jumping frequency and contact ratio, are discussed using the experimental data. Correlation relationships between the three parameters are investigated. The contact ratio and jumping frequency are identified as independent model parameters, and an empirical frequency-dependent function is derived for the impact factor. The feasibility of the proposed load model is established by comparing the simulated load curves with measured ones, and by comparing the acceleration responses of a single-degree-of-freedom system to the simulated and measured jumping loads. The results show that a realistic individual jumping load can be generated by the proposed method. This can then be used to assess the dynamic response of assembly structures.

  16. Non-Shock Initiation Model for Explosive Families: Experimental Results

    NASA Astrophysics Data System (ADS)

    Anderson, M. U.; Todd, S. N.; Caipen, T. L.; Jensen, C. B.; Hughs, C. G.

    2009-12-01

    The "DaMaGe-Initiated-Reaction" (DMGIR) computational model has been developed to predict the response of high explosives to non-shock mechanical insults. The distinguishing feature of this model is the introduction of a damage variable, which relates the evolution of damage to the initiation of a reaction in the explosive, and its growth to detonation. Specifically designed experiments were used to study the initiation process of each explosive family with embedded shock sensors and optical diagnostics. The experimental portion of this model development began with a study of PBXN-5 to develop DMGIR model coefficients for the rigid plastic bonded family, followed by studies of the cast, and bulk-moldable explosive families. The experimental results show an initiation mechanism that is related to input energy and material damage, with well defined initiation thresholds for each explosive family. These initiation details will extend the predictive capability of the DMGIR model from the rigid family into the cast and bulk-moldable families.

  17. Non-shock initiation model for explosive families : experimental results.

    SciTech Connect

    Anderson, Mark U.; Jensen, Charles B.; Todd, Steven N.; Hugh, Chance G.; Caipen, Terry L.

    2010-03-01

    The 'DaMaGe-Initiated-Reaction' (DMGIR) computational model has been developed to predict the response of high explosives to non-shock mechanical insults. The distinguishing feature of this model is the introduction of a damage variable, which relates the evolution of damage to the initiation of a reaction in the explosive, and its growth to detonation. Specifically designed experiments were used to study the initiation process of each explosive family with embedded shock sensors and optical diagnostics. The experimental portion of this model development began with a study of PBXN-5 to develop DMGIR model coefficients for the rigid plastic bonded family, followed by studies of the cast, and bulk-moldable explosive families. The experimental results show an initiation mechanism that is related to input energy and material damage, with well defined initiation thresholds for each explosive family. These initiation details will extend the predictive capability of the DMGIR model from the rigid family into the cast and bulk-moldable families.

  18. Modeling and experimental characterization of electromigration in interconnect trees

    NASA Astrophysics Data System (ADS)

    Thompson, C. V.; Hau-Riege, S. P.; Andleigh, V. K.

    1999-11-01

    Most modeling and experimental characterization of interconnect reliability is focussed on simple straight lines terminating at pads or vias. However, laid-out integrated circuits often have interconnects with junctions and wide-to-narrow transitions. In carrying out circuit-level reliability assessments it is important to be able to assess the reliability of these more complex shapes, generally referred to as `trees.' An interconnect tree consists of continuously connected high-conductivity metal within one layer of metallization. Trees terminate at diffusion barriers at vias and contacts, and, in the general case, can have more than one terminating branch when they include junctions. We have extended the understanding of `immortality' demonstrated and analyzed for straight stud-to-stud lines, to trees of arbitrary complexity. This leads to a hierarchical approach for identifying immortal trees for specific circuit layouts and models for operation. To complete a circuit-level-reliability analysis, it is also necessary to estimate the lifetimes of the mortal trees. We have developed simulation tools that allow modeling of stress evolution and failure in arbitrarily complex trees. We are testing our models and simulations through comparisons with experiments on simple trees, such as lines broken into two segments with different currents in each segment. Models, simulations and early experimental results on the reliability of interconnect trees are shown to be consistent.

  19. Experimental Models to Study Lymphatic and Blood Vascular Metastasis

    PubMed Central

    Chen, Lu; Wu, Lily

    2011-01-01

    As a model system for the understanding of human cancer, the mouse has proved immensely valuable. Indeed, studies of mouse models have helped to define the nature of cancer as a genetic disease and demonstrated the causal role of genetic events found in tumors. As an experimental platform, they have provided critical insight into the process of tumor metastasis in the lymphovascular system. Once viewed with skepticism, mouse models are now an integral arm of basic and clinical cancer research. The use of a genetically tractable organism that shares organ systems and an immense degree of genetic similarity to humans provides a means to examine multiple features of human disease. Mouse models enable development and testing of new approaches to disease prevention and treatment, identification of early diagnostic markers and novel therapeutic targets, and an understanding of the in vivo biology and genetics of tumor initiation, promotion, progression, and metastasis. This review summarizes recent mouse models for lymphangiogenesis and the process of lymphovascular metastasis, focusing on the use of the cornea as an experimental platform for lymphangiogenesis in inflammation and immunity, and on the use of molecular and viral vector mediated imaging and to identify and monitor lymph node metastases of prostate cancer. PMID:21480239

  20. Analogue earthquakes and seismic cycles: experimental modelling across timescales

    NASA Astrophysics Data System (ADS)

    Rosenau, Matthias; Corbi, Fabio; Dominguez, Stephane

    2017-05-01

    Earth deformation is a multi-scale process ranging from seconds (seismic deformation) to millions of years (tectonic deformation). Bridging short- and long-term deformation and developing seismotectonic models has been a challenge in experimental tectonics for more than a century. Since the formulation of Reid's elastic rebound theory 100 years ago, laboratory mechanical models combining frictional and elastic elements have been used to study the dynamics of earthquakes. In the last decade, with the advent of high-resolution monitoring techniques and new rock analogue materials, laboratory earthquake experiments have evolved from simple spring-slider models to scaled analogue models. This evolution was accomplished by advances in seismology and geodesy along with relatively frequent occurrences of large earthquakes in the past decade. This coincidence has significantly increased the quality and quantity of relevant observations in nature and triggered a new understanding of earthquake dynamics. We review here the developments in analogue earthquake modelling with a focus on those seismotectonic scale models that are directly comparable to observational data on short to long timescales. We lay out the basics of analogue modelling, namely scaling, materials and monitoring, as applied in seismotectonic modelling. An overview of applications highlights the contributions of analogue earthquake models in bridging timescales of observations including earthquake statistics, rupture dynamics, ground motion, and seismic-cycle deformation up to seismotectonic evolution.

  1. Waste glass corrosion modeling: Comparison with experimental results

    SciTech Connect

    Bourcier, W.L.

    1993-11-01

    A chemical model of glass corrosion will be used to predict the rates of release of radionuclides from borosilicate glass waste forms in high-level waste repositories. The model will be used both to calculate the rate of degradation of the glass, and also to predict the effects of chemical interactions between the glass and repository materials such as spent fuel, canister and container materials, backfill, cements, grouts, and others. Coupling between the degradation processes affecting all these materials is expected. Models for borosilicate glass dissolution must account for the processes of (1) kinetically-controlled network dissolution, (2) precipitation of secondary phases, (3) ion exchange, (4) rate-limiting diffusive transport of silica through a hydrous surface reaction layer, and (5) specific glass surface interactions with dissolved cations and anions. Current long-term corrosion models for borosilicate glass employ a rate equation consistent with transition state theory embodied in a geochemical reaction-path modeling program that calculates aqueous phase speciation and mineral precipitation/dissolution. These models are currently under development. Future experimental and modeling work to better quantify the rate-controlling processes and validate these models are necessary before the models can be used in repository performance assessment calculations.

  2. Mathematical models and the experimental analysis of behavior.

    PubMed

    Mazur, James E

    2006-03-01

    The use of mathematical models in the experimental analysis of behavior has increased over the years, and they offer several advantages. Mathematical models require theorists to be precise and unambiguous, often allowing comparisons of competing theories that sound similar when stated in words. Sometimes different mathematical models may make equally accurate predictions for a large body of data. In such cases, it is important to find and investigate situations for which the competing models make different predictions because, unless two models are actually mathematically equivalent, they are based on different assumptions about the psychological processes that underlie an observed behavior. Mathematical models developed in basic behavioral research have been used to predict and control behavior in applied settings, and they have guided research in other areas of psychology. A good mathematical model can provide a common framework for understanding what might otherwise appear to be diverse and unrelated behavioral phenomena. Because psychologists vary in their quantitative skills and in their tolerance for mathematical equations, it is important for those who develop mathematical models of behavior to find ways (such as verbal analogies, pictorial representations, or concrete examples) to communicate the key premises of their models to nonspecialists.

  3. Experimental design schemes for learning Boolean network models

    PubMed Central

    Atias, Nir; Gershenzon, Michal; Labazin, Katia; Sharan, Roded

    2014-01-01

    Motivation: A holy grail of biological research is a working model of the cell. Current modeling frameworks, especially in the protein–protein interaction domain, are mostly topological in nature, calling for stronger and more expressive network models. One promising alternative is logic-based or Boolean network modeling, which was successfully applied to model signaling regulatory circuits in human. Learning such models requires observing the system under a sufficient number of different conditions. To date, the amount of measured data is the main bottleneck in learning informative Boolean models, underscoring the need for efficient experimental design strategies. Results: We developed novel design approaches that greedily select an experiment to be performed so as to maximize the difference or the entropy in the results it induces with respect to current best-fit models. Unique to our maximum difference approach is the ability to account for all (possibly exponential number of) Boolean models displaying high fit to the available data. We applied both approaches to simulated and real data from the EFGR and IL1 signaling systems in human. We demonstrate the utility of the developed strategies in substantially improving on a random selection approach. Our design schemes highlight the redundancy in these datasets, leading up to 11-fold savings in the number of experiments to be performed. Availability and implementation: Source code will be made available upon acceptance of the manuscript. Contact: roded@post.tau.ac.il PMID:25161232

  4. Diffusion models in experimental psychology: a practical introduction.

    PubMed

    Voss, Andreas; Nagler, Markus; Lerche, Veronika

    2013-01-01

    Stochastic diffusion models (Ratcliff, 1978) can be used to analyze response time data from binary decision tasks. They provide detailed information about cognitive processes underlying the performance in such tasks. Most importantly, different parameters are estimated from the response time distributions of correct responses and errors that map (1) the speed of information uptake, (2) the amount of information used to make a decision, (3) possible decision biases, and (4) the duration of nondecisional processes. Although this kind of model can be applied to many experimental paradigms and provides much more insight than the analysis of mean response times can, it is still rarely used in cognitive psychology. In the present paper, we provide comprehensive information on the theory of the diffusion model, as well as on practical issues that have to be considered for implementing the model.

  5. Fundamental Mistuning Model for Probabilistic Analysis Studied Experimentally

    NASA Technical Reports Server (NTRS)

    Griffin, Jerry H.

    2005-01-01

    The Fundamental Mistuning Model (FMM) is a reduced-order model for efficiently calculating the forced response of a mistuned bladed disk. FMM ID is a companion program that determines the mistuning in a particular rotor. Together, these methods provide a way to acquire mistuning data in a population of bladed disks and then simulate the forced response of the fleet. This process was tested experimentally at the NASA Glenn Research Center, and the simulated results were compared with laboratory measurements of a "fleet" of test rotors. The method was shown to work quite well. It was found that the accuracy of the results depends on two factors: (1) the quality of the statistical model used to characterize mistuning and (2) how sensitive the system is to errors in the statistical modeling.

  6. Experimental models in vaccine research: malaria and leishmaniasis.

    PubMed

    Teixeira, C; Gomes, R

    2013-02-01

    Animal models have a long history of being useful tools, not only to test and select vaccines, but also to help understand the elaborate details of the immune response that follows infection. Different models have been extensively used to investigate putative immunological correlates of protection against parasitic diseases that are important to reach a successful vaccine. The greatest challenge has been the improvement and adaptation of these models to reflect the reality of human disease and the screening of vaccine candidates capable of overcoming the challenge of natural transmission. This review will discuss the advantages and challenges of using experimental animal models for vaccine development and how the knowledge achieved can be extrapolated to human disease by looking into two important parasitic diseases: malaria and leishmaniasis.

  7. Experimental models in vaccine research: malaria and leishmaniasis

    PubMed Central

    Teixeira, C.; Gomes, R.

    2013-01-01

    Animal models have a long history of being useful tools, not only to test and select vaccines, but also to help understand the elaborate details of the immune response that follows infection. Different models have been extensively used to investigate putative immunological correlates of protection against parasitic diseases that are important to reach a successful vaccine. The greatest challenge has been the improvement and adaptation of these models to reflect the reality of human disease and the screening of vaccine candidates capable of overcoming the challenge of natural transmission. This review will discuss the advantages and challenges of using experimental animal models for vaccine development and how the knowledge achieved can be extrapolated to human disease by looking into two important parasitic diseases: malaria and leishmaniasis. PMID:23369975

  8. Precisely parameterized experimental and computational models of tissue organization.

    PubMed

    Molitoris, Jared M; Paliwal, Saurabh; Sekar, Rajesh B; Blake, Robert; Park, JinSeok; Trayanova, Natalia A; Tung, Leslie; Levchenko, Andre

    2016-02-01

    Patterns of cellular organization in diverse tissues frequently display a complex geometry and topology tightly related to the tissue function. Progressive disorganization of tissue morphology can lead to pathologic remodeling, necessitating the development of experimental and theoretical methods of analysis of the tolerance of normal tissue function to structural alterations. A systematic way to investigate the relationship of diverse cell organization to tissue function is to engineer two-dimensional cell monolayers replicating key aspects of the in vivo tissue architecture. However, it is still not clear how this can be accomplished on a tissue level scale in a parameterized fashion, allowing for a mathematically precise definition of the model tissue organization and properties down to a cellular scale with a parameter dependent gradual change in model tissue organization. Here, we describe and use a method of designing precisely parameterized, geometrically complex patterns that are then used to control cell alignment and communication of model tissues. We demonstrate direct application of this method to guiding the growth of cardiac cell cultures and developing mathematical models of cell function that correspond to the underlying experimental patterns. Several anisotropic patterned cultures spanning a broad range of multicellular organization, mimicking the cardiac tissue organization of different regions of the heart, were found to be similar to each other and to isotropic cell monolayers in terms of local cell-cell interactions, reflected in similar confluency, morphology and connexin-43 expression. However, in agreement with the model predictions, different anisotropic patterns of cell organization, paralleling in vivo alterations of cardiac tissue morphology, resulted in variable and novel functional responses with important implications for the initiation and maintenance of cardiac arrhythmias. We conclude that variations of tissue geometry and topology

  9. Precisely parameterized experimental and computational models of tissue organization†

    PubMed Central

    Sekar, Rajesh B.; Blake, Robert; Park, JinSeok; Trayanova, Natalia A.; Tung, Leslie; Levchenko, Andre

    2016-01-01

    Patterns of cellular organization in diverse tissues frequently display a complex geometry and topology tightly related to the tissue function. Progressive disorganization of tissue morphology can lead to pathologic remodeling, necessitating the development of experimental and theoretical methods of analysis of the tolerance of normal tissue function to structural alterations. A systematic way to investigate the relationship of diverse cell organization to tissue function is to engineer two-dimensional cell monolayers replicating key aspects of the in vivo tissue architecture. However, it is still not clear how this can be accomplished on a tissue level scale in a parameterized fashion, allowing for a mathematically precise definition of the model tissue organization and properties down to a cellular scale with a parameter dependent gradual change in model tissue organization. Here, we describe and use a method of designing precisely parameterized, geometrically complex patterns that are then used to control cell alignment and communication of model tissues. We demonstrate direct application of this method to guiding the growth of cardiac cell cultures and developing mathematical models of cell function that correspond to the underlying experimental patterns. Several anisotropic patterned cultures spanning a broad range of multicellular organization, mimicking the cardiac tissue organization of different regions of the heart, were found to be similar to each other and to isotropic cell monolayers in terms of local cell–cell interactions, reflected in similar confluency, morphology and connexin-43 expression. However, in agreement with the model predictions, different anisotropic patterns of cell organization, paralleling in vivo alterations of cardiac tissue morphology, resulted in variable and novel functional responses with important implications for the initiation and maintenance of cardiac arrhythmias. We conclude that variations of tissue geometry and

  10. Hydroforming Of Patchwork Blanks — Numerical Modeling And Experimental Validation

    NASA Astrophysics Data System (ADS)

    Lamprecht, Klaus; Merklein, Marion; Geiger, Manfred

    2005-08-01

    In comparison to the commonly applied technology of tailored blanks the concept of patchwork blanks offers a number of additional advantages. Potential application areas for patchwork blanks in automotive industry are e.g. local reinforcements of automotive closures, structural reinforcements of rails and pillars as well as shock towers. But even if there is a significant application potential for patchwork blanks in automobile production, industrial realization of this innovative technique is decelerated due to a lack of knowledge regarding the forming behavior and the numerical modeling of patchwork blanks. Especially for the numerical simulation of hydroforming processes, where one part of the forming tool is replaced by a fluid under pressure, advanced modeling techniques are required to ensure an accurate prediction of the blanks' forming behavior. The objective of this contribution is to provide an appropriate model for the numerical simulation of patchwork blanks' forming processes. Therefore, different finite element modeling techniques for patchwork blanks are presented. In addition to basic shell element models a combined finite element model consisting of shell and solid elements is defined. Special emphasis is placed on the modeling of the weld seam. For this purpose the local mechanical properties of the weld metal, which have been determined by means of Martens-hardness measurements and uniaxial tensile tests, are integrated in the finite element models. The results obtained from the numerical simulations are compared to experimental data from a hydraulic bulge test. In this context the focus is laid on laser- and spot-welded patchwork blanks.

  11. Experimental model for civilian ballistic brain injury biomechanics quantification.

    PubMed

    Zhang, Jiangyue; Yoganandan, Narayan; Pintar, Frank A; Guan, Yabo; Gennarelli, Thomas A

    2007-01-01

    Biomechanical quantification of projectile penetration using experimental head models can enhance the understanding of civilian ballistic brain injury and advance treatment. Two of the most commonly used handgun projectiles (25-cal, 275 m/s and 9 mm, 395 m/s) were discharged to spherical head models with gelatin and Sylgard simulants. Four ballistic pressure transducers recorded temporal pressure distributions at 308kHz, and temporal cavity dynamics were captured at 20,000 frames/second (fps) using high-speed digital video images. Pressures ranged from 644.6 to -92.8 kPa. Entry pressures in gelatin models were higher than exit pressures, whereas in Sylgard models entry pressures were lower or equivalent to exit pressures. Gelatin responded with brittle-type failure, while Sylgard demonstrated a ductile pattern through formation of micro-bubbles along projectile path. Temporary cavities in Sylgard models were 1.5-2x larger than gelatin models. Pressures in Sylgard models were more sensitive to projectile velocity and diameter increase, indicating Sylgard was more rate sensitive than gelatin. Based on failure patterns and brain tissue rate-sensitive characteristics, Sylgard was found to be an appropriate simulant. Compared with spherical projectile data, full-metal jacket (FMJ) projectiles produced different temporary cavity and pressures, demonstrating shape effects. Models using Sylgard gel and FMJ projectiles are appropriate to enhance understanding and mechanisms of ballistic brain injury.

  12. Of mice and men: modelling post-stroke depression experimentally

    PubMed Central

    Kronenberg, G; Gertz, K; Heinz, A; Endres, M

    2014-01-01

    At least one-third of stroke survivors suffer from depression. The development of comorbid depression after stroke is clinically highly significant because post-stroke depression is associated with increased mortality, slows recovery and leads to worse functional outcomes. Here, we review the evidence that post-stroke depression can be effectively modelled in experimental rodents via a variety of approaches. This opens an exciting new window onto the neurobiology of depression and permits probing potential underlying mechanisms such as disturbed cellular plasticity, neuroendocrine dysregulation, neuroinflammation, and neurodegeneration in a novel context. From the point of view of translational stroke research, extending the scope of experimental investigations beyond the study of short-term end points and, in particular, acute lesion size, may help improve the relevance of preclinical results to human disease. Furthermore, accumulating evidence from both clinical and experimental studies offers the tantalizing prospect of 5-hydroxytryptaminergic antidepressants as the first pharmacological therapy for stroke that would be available during the subacute and chronic phases of recovery. Interdisciplinary neuropsychiatric research will be called on to dissect the mechanisms underpinning the beneficial effects of antidepressants on stroke recovery. Linked Articles This article is part of a themed section on Animal Models in Psychiatry Research. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-20 PMID:24838087

  13. Sheet Hydroforming Process Numerical Model Improvement Through Experimental Results Analysis

    NASA Astrophysics Data System (ADS)

    Gabriele, Papadia; Antonio, Del Prete; Alfredo, Anglani

    2010-06-01

    The increasing application of numerical simulation in metal forming field has helped engineers to solve problems one after another to manufacture a qualified formed product reducing the required time [1]. Accurate simulation results are fundamental for the tooling and the product designs. The wide application of numerical simulation is encouraging the development of highly accurate simulation procedures to meet industrial requirements. Many factors can influence the final simulation results and many studies have been carried out about materials [2], yield criteria [3] and plastic deformation [4,5], process parameters [6] and their optimization. In order to develop a reliable hydromechanical deep drawing (HDD) numerical model the authors have been worked out specific activities based on the evaluation of the effective stiffness of the blankholder structure [7]. In this paper after an appropriate tuning phase of the blankholder force distribution, the experimental activity has been taken into account to improve the accuracy of the numerical model. In the first phase, the effective capability of the blankholder structure to transfer the applied load given by hydraulic actuators to the blank has been explored. This phase ended with the definition of an appropriate subdivision of the blankholder active surface in order to take into account the effective pressure map obtained for the given loads configuration. In the second phase the numerical results obtained with the developed subdivision have been compared with the experimental data of the studied model. The numerical model has been then improved, finding the best solution for the blankholder force distribution.

  14. The gas fluxing of aluminum: Mathematical modeling and experimental investigations

    NASA Astrophysics Data System (ADS)

    Fjeld, Autumn Marie

    Chlorine fluxing is an essential purification step in aluminum refining in which impurities such as Ca, Na, Li, and Mg are removed by bubbling a mixture of chlorine and argon gas through molten aluminum. The gas is injected into the fluxing vessel through a rotating shaft and impeller which simultaneously agitates the melt, while breaking up and dispersing gas bubbles through the liquid phase. The efficiency of impurity removal and control of toxic chlorine and chloride emissions are dependent upon the extent of gas dispersion or mixing, residence time of the bubbles, and surface area of the bubbles. Clearly the gas injection and distribution within the liquid metal cannot be directly observed and such operations are often poorly controlled and not well understood. Problems arise when the injection gas, i.e. chlorine, is not completely consumed by reaction with impurities and the excess is reported as emissions of chlorides such as toxic HCl. The intention is to improve the technology to eliminate this waste (saving on the energy entailed in the chlorine production and reducing pollution) by better dispersion of the injected gas throughout the metal. Previous experimental investigations using a capacitance probe, capable of immersion in liquid aluminum for several hours, have been carried out to detect bubbles in an industrial fluxing unit at the Alcoa Technical Center. Bubble frequency data have shown the bubbles to be fairly well dispersed in the areas of the fluxing unit, decreasing in observed bubble frequency with increasing distance from the impeller (source of gas injection). To gain further insight and add to our experimental findings, two computational models have been developed to simulate the complex two-phase fluid dynamics of a rotary gas injection system. The results of these two modeling approaches are presented and analyzed and compared to experimental bubble measurements gathered using the capacitance probe. Bubble size distributions and residence

  15. Modeling and experimental vibration analysis of nanomechanical cantilever active probes

    NASA Astrophysics Data System (ADS)

    Salehi-Khojin, Amin; Bashash, Saeid; Jalili, Nader

    2008-08-01

    Nanomechanical cantilever (NMC) active probes have recently received increased attention in a variety of nanoscale sensing and measurement applications. Current modeling practices call for a uniform cantilever beam without considering the intentional jump discontinuities associated with the piezoelectric layer attachment and the NMC cross-sectional step. This paper presents a comprehensive modeling framework for modal characterization and dynamic response analysis of NMC active probes with geometrical discontinuities. The entire length of the NMC is divided into three segments of uniform beams followed by applying appropriate continuity conditions. The characteristics matrix equation is then used to solve for system natural frequencies and mode shapes. Using an equivalent electromechanical moment of a piezoelectric layer, forced motion analysis of the system is carried out. An experimental setup consisting of a commercial NMC active probe from Veeco and a state-of-the-art microsystem analyzer, the MSA-400 from Polytec, is developed to verify the theoretical developments proposed here. Using a parameter estimation technique based on minimizing the modeling error, optimal values of system parameters are identified. Mode shapes and the modal frequency response of the system for the first three modes determined from the proposed model are compared with those obtained from the experiment and commonly used theory for uniform beams. Results indicate that the uniform beam model fails to accurately predict the actual system response, especially in multiple-mode operation, while the proposed discontinuous beam model demonstrates good agreement with the experimental data. Such detailed and accurate modeling framework can lead to significant enhancement in the sensitivity of piezoelectric-based NMC sensors for use in variety of sensing and imaging applications.

  16. Experimental validation of Swy-2 clay standard's PHREEQC model

    NASA Astrophysics Data System (ADS)

    Szabó, Zsuzsanna; Hegyfalvi, Csaba; Freiler, Ágnes; Udvardi, Beatrix; Kónya, Péter; Székely, Edit; Falus, György

    2017-04-01

    One of the challenges of the present century is to limit the greenhouse gas emissions for the mitigation of climate change which is possible for example by a transitional technology, CCS (Carbon Capture and Storage) and, among others, by the increase of nuclear proportion in the energy mix. Clay minerals are considered to be responsible for the low permeability and sealing capacity of caprocks sealing off stored CO2 and they are also the main constituents of bentonite in high level radioactive waste disposal facilities. The understanding of clay behaviour in these deep geological environments is possible through laboratory batch experiments of well-known standards and coupled geochemical models. Such experimentally validated models are scarce even though they allow deriving more precise long-term predictions of mineral reactions and rock and bentonite degradation underground and, therefore, ensuring the safety of the above technologies and increase their public acceptance. This ongoing work aims to create a kinetic geochemical model of Na-montmorillonite standard Swy-2 in the widely used PHREEQC code, supported by solution and mineral composition results from batch experiments. Several four days experiments have been carried out in 1:35 rock:water ratio at atmospheric conditions, and with inert and CO2 supercritical phase at 100 bar and 80 ⁰C relevant for the potential Hungarian CO2 reservoir complex. Solution samples have been taken during and after experiments and their compositions were measured by ICP-OES. The treated solid phase has been analysed by XRD and ATR-FTIR and compared to in-parallel measured references (dried Swy-2). Kinetic geochemical modelling of the experimental conditions has been performed by PHREEQC version 3 using equations and kinetic rate parameters from the USGS report of Palandri and Kharaka (2004). The visualization of experimental and numerous modelling results has been automatized by R. Experiments and models show very fast

  17. Identification of Computational and Experimental Reduced-Order Models

    NASA Technical Reports Server (NTRS)

    Silva, Walter A.; Hong, Moeljo S.; Bartels, Robert E.; Piatak, David J.; Scott, Robert C.

    2003-01-01

    The identification of computational and experimental reduced-order models (ROMs) for the analysis of unsteady aerodynamic responses and for efficient aeroelastic analyses is presented. For the identification of a computational aeroelastic ROM, the CFL3Dv6.0 computational fluid dynamics (CFD) code is used. Flutter results for the AGARD 445.6 Wing and for a Rigid Semispan Model (RSM) computed using CFL3Dv6.0 are presented, including discussion of associated computational costs. Modal impulse responses of the unsteady aerodynamic system are computed using the CFL3Dv6.0 code and transformed into state-space form. The unsteady aerodynamic state-space ROM is then combined with a state-space model of the structure to create an aeroelastic simulation using the MATLAB/SIMULINK environment. The MATLAB/SIMULINK ROM is then used to rapidly compute aeroelastic transients, including flutter. The ROM shows excellent agreement with the aeroelastic analyses computed using the CFL3Dv6.0 code directly. For the identification of experimental unsteady pressure ROMs, results are presented for two configurations: the RSM and a Benchmark Supercritical Wing (BSCW). Both models were used to acquire unsteady pressure data due to pitching oscillations on the Oscillating Turntable (OTT) system at the Transonic Dynamics Tunnel (TDT). A deconvolution scheme involving a step input in pitch and the resultant step response in pressure, for several pressure transducers, is used to identify the unsteady pressure impulse responses. The identified impulse responses are then used to predict the pressure responses due to pitching oscillations at several frequencies. Comparisons with the experimental data are then presented.

  18. Experimental realization of the topological Haldane model with ultracold fermions.

    PubMed

    Jotzu, Gregor; Messer, Michael; Desbuquois, Rémi; Lebrat, Martin; Uehlinger, Thomas; Greif, Daniel; Esslinger, Tilman

    2014-11-13

    The Haldane model on a honeycomb lattice is a paradigmatic example of a Hamiltonian featuring topologically distinct phases of matter. It describes a mechanism through which a quantum Hall effect can appear as an intrinsic property of a band structure, rather than being caused by an external magnetic field. Although physical implementation has been considered unlikely, the Haldane model has provided the conceptual basis for theoretical and experimental research exploring topological insulators and superconductors. Here we report the experimental realization of the Haldane model and the characterization of its topological band structure, using ultracold fermionic atoms in a periodically modulated optical honeycomb lattice. The Haldane model is based on breaking both time-reversal symmetry and inversion symmetry. To break time-reversal symmetry, we introduce complex next-nearest-neighbour tunnelling terms, which we induce through circular modulation of the lattice position. To break inversion symmetry, we create an energy offset between neighbouring sites. Breaking either of these symmetries opens a gap in the band structure, which we probe using momentum-resolved interband transitions. We explore the resulting Berry curvatures, which characterize the topology of the lowest band, by applying a constant force to the atoms and find orthogonal drifts analogous to a Hall current. The competition between the two broken symmetries gives rise to a transition between topologically distinct regimes. By identifying the vanishing gap at a single Dirac point, we map out this transition line experimentally and quantitatively compare it to calculations using Floquet theory without free parameters. We verify that our approach, which allows us to tune the topological properties dynamically, is suitable even for interacting fermionic systems. Furthermore, we propose a direct extension to realize spin-dependent topological Hamiltonians.

  19. Experimental realization of the topological Haldane model with ultracold fermions

    NASA Astrophysics Data System (ADS)

    Jotzu, Gregor; Messer, Michael; Desbuquois, Rémi; Lebrat, Martin; Uehlinger, Thomas; Greif, Daniel; Esslinger, Tilman

    2014-11-01

    The Haldane model on a honeycomb lattice is a paradigmatic example of a Hamiltonian featuring topologically distinct phases of matter. It describes a mechanism through which a quantum Hall effect can appear as an intrinsic property of a band structure, rather than being caused by an external magnetic field. Although physical implementation has been considered unlikely, the Haldane model has provided the conceptual basis for theoretical and experimental research exploring topological insulators and superconductors. Here we report the experimental realization of the Haldane model and the characterization of its topological band structure, using ultracold fermionic atoms in a periodically modulated optical honeycomb lattice. The Haldane model is based on breaking both time-reversal symmetry and inversion symmetry. To break time-reversal symmetry, we introduce complex next-nearest-neighbour tunnelling terms, which we induce through circular modulation of the lattice position. To break inversion symmetry, we create an energy offset between neighbouring sites. Breaking either of these symmetries opens a gap in the band structure, which we probe using momentum-resolved interband transitions. We explore the resulting Berry curvatures, which characterize the topology of the lowest band, by applying a constant force to the atoms and find orthogonal drifts analogous to a Hall current. The competition between the two broken symmetries gives rise to a transition between topologically distinct regimes. By identifying the vanishing gap at a single Dirac point, we map out this transition line experimentally and quantitatively compare it to calculations using Floquet theory without free parameters. We verify that our approach, which allows us to tune the topological properties dynamically, is suitable even for interacting fermionic systems. Furthermore, we propose a direct extension to realize spin-dependent topological Hamiltonians.

  20. Collection methods of trematode eggs using experimental animal models.

    PubMed

    Tsubokawa, Daigo; Sugiyama, Hiromu; Mikami, Fusako; Shibata, Katsumasa; Shibahara, Toshiyuki; Fukuda, Koichi; Takamiya, Shinzaburo; Yamasaki, Hiroshi; Nakamura, Takeshi; Tsuji, Naotoshi

    2016-10-01

    Although observing the eggs of human parasitic helminth is essential for medical education in parasitology, opportunities for collection of the eggs are limited. Collection of the eggs using experimental animal models is needed for a sustainable supply. The metacercariae of three trematode species, Paragonimus westermani, Clonorchis sinensis and Metagonimus yokogawai, were collected from the second intermediate hosts: freshwater crabs and fishes, which were obtained using online shopping in Japan, and inoculated to experimental animal rat and dog. Consequently, eggs of the three trematode species were obtained abundantly from the feces of the animals. The eggs are being used for student training in several Japanese universities. In this article, we introduce the collection procedures for trematode eggs.

  1. [Efficacy of polyprenyl phosphates in the experimental genital herpes model].

    PubMed

    Narovlyansky, A N; Ivanova, A M; Shevlyagina, N V; Didenko, L V; Borovaya, T G; Izmest'eva, A V; Sanin, A V; Pronin, A V; Ershov, F I

    2015-01-01

    An experimental model of the primary genital herpes (herpes simplex type 2, HSV-2) in the female guinea pigs was suggested to study the infectious process activity of polyprenyl phosphates (PPP) and PPP+acyclovir (AC) complex treatment. The morphofunctional features of the guinea pig ovaries were studied in the control and experimental groups (the latter were inoculated with PPP and/or AC as a primary infection treatment) at the stage of the recurrent genital herpes aggravation. It was shown that in the case of combined PPP +AC use significant changes in the disease symptoms were observed, as well as a decrease in the infectious process activity and duration, and positive remote effect on the ovarian morphophysiology.

  2. Experimental modelling of material interfaces with ultracold atoms

    NASA Astrophysics Data System (ADS)

    Corcovilos, Theodore A.; Brooke, Robert W. A.; Gillis, Julie; Ruggiero, Anthony C.; Tiber, Gage D.; Zaccagnini, Christopher A.

    2014-05-01

    We present a design for a new experimental apparatus for studying the physics of junctions using ultracold potassium atoms (K-39 and K-40). Junctions will be modeled using holographically projected 2D optical potentials. These potentials can be engineered to contain arbitrary features such as junctions between dissimilar lattices or the intentional insertion of defects. Long-term investigation goals include edge states, scattering at defects, and quantum depletion at junctions. In this poster we show our overall apparatus design and our progress in building experimental subsystems including the vacuum system, extended cavity diode lasers, digital temperature and current control circuits for the lasers, and the saturated absorption spectroscopy system. Funding provided by the Bayer School of Natural and Environmental.

  3. Huntington's disease and mitochondrial alterations: emphasis on experimental models.

    PubMed

    Pérez-De la Cruz, Verónica; Carrillo-Mora, Paul; Santamaría, Abel

    2010-06-01

    Huntington's disease (HD) is an inheritable neurological disorder coursing with degeneration of basal ganglia and producing chorea and dementia. One common factor accounting for neurodegeneration in this disorder is mitochondrial deterioration at both morphologic and functional levels. The development of experimental models in animals or cell preparations to resemble pathologic and pathogenic conditions of this disorder has served for more than four decades to describe part of the mechanistic alterations that could be occurring in mitochondria of HD patients, and the subsequent design of therapeutic alternatives where mitochondrial alterations are the primary target. In this minireview we describe some of the most relevant studies at the experimental level, giving support to the hypothesis that mitochondria play a central role in HD pathogenesis.

  4. Experimental modelling of eddy currents and deflection for tokamak limiters

    SciTech Connect

    Hua, T.Q.; Knott, M.J.; Turner, L.R.; Wehrle, R.B.

    1986-11-01

    During plasma disruptions in a tokamak fusion reactor, eddy currents are induced in the limiters and other conducting structures surrounding the plasma. Interactions between these currents with the toroidal field causes deflection and stress in the structural components. The structural motion in the strong magnetic field induces additional eddy current opposing the initial eddy current and modifying subsequent structural dynamics. Therefore, the motion and current are coupled and must be solved simultaneously. The coupling between current and deflection in cantilevered beams was investigated experimentally. The beams provide a simple model for the limiter blade of a tokamak fusion reactor. Several test pieces and various magnetic field conditions were employed to study the extend of the coupling effect from weak to strong coupling. Experimental results are compared with analytical predictions.

  5. Experimental Investigation and Computational Modeling of Hydrodynamics in Bifurcating Microchannels

    PubMed Central

    Janakiraman, Vijayakumar; Sastry, Sudeep; Kadambi, Jaikrishnan R.; Baskaran, Harihara

    2008-01-01

    Methods involving microfluidics have been used in several chemical, biological and medical applications. In particular, a network of bifurcating microchannels can be used to distribute flow in a large space. In this work, we carried out experiments to determine hydrodynamic characteristics of bifurcating microfluidic networks. We measured pressure drop across bifurcating networks of various complexities for various flow rates. We also measured planar velocity fields in these networks by using particle image velocimetry. We further analyzed hydrodynamics in these networks using mathematical and computational modeling. Our results show that the experimental frictional resistances of complex bifurcating microchannels are about 30% greater than that predicted by Navier-Stokes’ equations. Experimentally measured velocity profiles indicate that flow distributes equally at a bifurcation regardless of the complexity of the network. Flow division other than bifurcation such as trifurcation or quadruplication can lead to heterogeneities. These findings were verified by the results from the numerical simulations. PMID:18175219

  6. Experimentation and numerical modeling of forging induced bending (FIB) process

    NASA Astrophysics Data System (ADS)

    Naseem, S.; van den Boogaard, A. H.

    2016-10-01

    Accurate prediction of the final shape using numerical modeling has been a top priority in the field of sheet and bulk forming. Better shape prediction is the result of a better estimation of the physical stress and strain state. For experimental and numerical investigations of such estimations, simple benchmark processes are used. In this paper a benchmark process involving forging (flattening) of sheet metal between punch and die with negative clearance is proposed. The introduced material flow results in bending. Easy measurability of the angle of this bend makes this process suitable for validation purpose. Physical experiments are performed to characterize this bending angle due to flattening. Furthermore a numerical model is developed to capture this phenomenon. The main focus of this paper is the validation of the numerical model in terms of accurate prediction of the physical results.

  7. A two-Higgs-doublet model facing experimental hints

    NASA Astrophysics Data System (ADS)

    Crivellin, Andreas; Heeck, Julian; Stoffer, Peter

    2016-04-01

    Physics beyond the Standard Model has so far eluded our experimental probes. Nevertheless, a number of interesting anomalies have accumulated that can be taken as hints towards new physics: BaBar, Belle, and LHCb have found deviations of approximately 3:8σ in B → Dτν and B → D*τν; the anomalous magnetic moment of the muon differs by about 3σ from the theoretic prediction; the branching ratio for τ → μνν is about 2σ above the Standard Model expectation; and CMS and ATLAS found hints for a non-zero decay rate of h → μτ at 2.6σ. Here we consider these processes within a lepton-specific two-Higgs doublet model with additional non-standard Yukawa couplings and show how (and which of) these excesses can be accommodated.

  8. Tidal deformation of planets: experience in experimental modeling.

    NASA Astrophysics Data System (ADS)

    Bobryakov, A. P.; Revuzhenko, A. F.; Shemyakin, E. I.

    1992-06-01

    Two types of apparatus are described for laboratory modeling of tidal deformation. Plane deformation occurs in the first, and the model of the body has the shape of an elliptical cylinder; in the second three-dimensional deformation occurs, and the model is spheroidal in shape. In both cases displacements simulating motion of the tidal wave are assigned on the boundary. A global mechanism of directed mass transfer has been discovered. It is connected with transformation of vertical displacements to horizontal ones. The internal particles describe almost closed trajectories in one complete rotation of the tidal wave, but do not return to their original position. Residual displacements accumulate with increasing number of cycles and lead to differential rotation of internal masses. Questions surrounding experimental measurement of energy dissipation and the role of an internal rigid core are investigated. The effect of directed transfer on the physical fields of planets is discussed.

  9. Experimentally driven atomistic model of 1,2 polybutadiene

    SciTech Connect

    Gkourmpis, Thomas; Mitchell, Geoffrey R.

    2014-02-07

    We present an efficient method of combining wide angle neutron scattering data with detailed atomistic models, allowing us to perform a quantitative and qualitative mapping of the organisation of the chain conformation in both glass and liquid phases. The structural refinement method presented in this work is based on the exploitation of the intrachain features of the diffraction pattern and its intimate linkage with atomistic models by the use of internal coordinates for bond lengths, valence angles, and torsion rotations. Atomic connectivity is defined through these coordinates that are in turn assigned by pre-defined probability distributions, thus allowing for the models in question to be built stochastically. Incremental variation of these coordinates allows for the construction of models that minimise the differences between the observed and calculated structure factors. We present a series of neutron scattering data of 1,2 polybutadiene at the region 120–400 K. Analysis of the experimental data yields bond lengths for Cî—¸C and C î—» C of 1.54 Å and 1.35 Å, respectively. Valence angles of the backbone were found to be at 112° and the torsion distributions are characterised by five rotational states, a three-fold trans-skew± for the backbone and gauche± for the vinyl group. Rotational states of the vinyl group were found to be equally populated, indicating a largely atactic chan. The two backbone torsion angles exhibit different behaviour with respect to temperature of their trans population, with one of them adopting an almost all trans sequence. Consequently, the resulting configuration leads to a rather persistent chain, something indicated by the value of the characteristic ratio extrapolated from the model. We compare our results with theoretical predictions, computer simulations, RIS models and previously reported experimental results.

  10. Electromechanical properties of smart aggregate: theoretical modeling and experimental validation

    NASA Astrophysics Data System (ADS)

    Wang, Jianjun; Kong, Qingzhao; Shi, Zhifei; Song, Gangbing

    2016-09-01

    Smart aggregate (SA), as a piezoceramic-based multi-functional device, is formed by sandwiching two lead zirconate titanate (PZT) patches with copper shielding between a pair of solid-machined cylindrical marble blocks with epoxy. Previous researches have successfully demonstrated the capability and reliability of versatile SAs to monitor the structural health of concrete structures. However, the previous works concentrated mainly on the applications of SAs in structural health monitoring; no reasonable theoretical model of SAs was proposed. In this paper, electromechanical properties of SAs were investigated using a proposed theoretical model. Based on one dimensional linear theory of piezo-elasticity, the dynamic solutions of a SA subjected to an external harmonic voltage were solved. Further, the electric impedance of the SA was computed, and the resonance and anti-resonance frequencies were calculated based on derived equations. Numerical analysis was conducted to discuss the effects of the thickness of epoxy layer and the dimension of PZT patch on the fundamental resonance and anti-resonance frequencies as well as the corresponding electromechanical coupling factor. The dynamic solutions based on the proposed theoretical model were further experimentally verified with two SA samples. The fundamental resonance and anti-resonance frequencies of SAs show good agreements in both theoretical and experimental results. The presented analysis and results contribute to the overall understanding of SA properties and help to optimize the working frequencies of SAs in structural health monitoring of civil structures.

  11. Experimental model of non-controlled hemorrhagic shock in pigs.

    PubMed

    Cavalcante, Fernanda Paula; Nani, Ricardo Souza; Filho, Joel Avancini Rocha; Auler Junior, José Otávio Costa; Carmona, Maria José Carvalho; Machado, Marcel Cerqueira Cesar

    2011-01-01

    A better understanding of pathophysiologic changes associated to trauma and hemorrhagic shock can help the development of therapies capable of reducing trauma-related mortality. The objective of this study was to describe a model of non-controlled hemorrhagic shock in pigs. Animals received ketamine and midazolam as pre-anesthetic medications. Anesthesia was induced with propofol, and tracheal intubation was performed with the animals on spontaneous ventilation. After intubation neuromuscular blockade was performed. Animals were maintained in controlled mechanical ventilation and normocapnia. Anesthesia was maintained with propofol and fentanyl as needed. Saline was infused during the entire preparation period. Cardioscope, pulse oximeter, invasive blood pressure, volumetric catheter in the pulmonary artery, and urine output by cystostomy were used. Experimental model: after the initial recording of hemodynamic, metabolic, and coagulation variables, right subcostal incision and left lobe liver biopsy were performed. Anesthetic infusion was reduced while the infusion of saline was interrupted. An incision 12cm long 2cm deep was performed in the right liver lobe followed by digital divulsion of the wound. During the hemorrhagic phase, an aspiration probe was placed close to the wound and the volume of aspirated blood was recorded. When mean arterial pressure reached 40mmHg and bleeding was above 700mL the intervention phase was initiated according to the type of study. The development of experimental models to reduce high mortality and costs related to trauma is important. Copyright © 2011 Elsevier Editora Ltda. All rights reserved.

  12. Tyre tread-block friction: modelling, simulation and experimental validation

    NASA Astrophysics Data System (ADS)

    Wallaschek, Jörg; Wies, Burkard

    2013-07-01

    Pneumatic tyres are used in vehicles since the beginning of the last century. They generate braking and steering forces for bicycles, motor cycles, cars, busses, trucks, agricultural vehicles and aircraft. These forces are generated in the usually very small contact area between tyre and road and their performance characteristics are of eminent importance for safety and comfort. Much research has been addressed to optimise tyre design with respect to footprint pressure and friction. In this context, the development of virtual tyre prototypes, that is, simulation models for the tyre, has grown to a science in its own. While the modelling of the structural dynamics of the tyre has reached a very advanced level, which allows to take into account effects like the rate-independent inelasticity of filled elastomers or the transient 3D deformations of the ply-reinforced tread, shoulder and sidewalls, little is known about the friction between tread-block elements and road. This is particularly obvious in the case when snow, ice, water or a third-body layer are present in the tyre-road contact. In the present paper, we give a survey on the present state of knowledge in the modelling, simulation and experimental validation of tyre tread-block friction processes. We concentrate on experimental techniques.

  13. Associative learning deficit in two experimental models of hepatic encephalopathy.

    PubMed

    Méndez, Marta; Méndez-López, Magdalena; López, Laudino; Aller, María Angeles; Arias, Jaime; Arias, Jorge L

    2009-03-17

    People with hepatic insufficiency can develop hepatic encephalopathy (HE), a complex neuropsychological syndrome covering a wide range of neurological and cognitive and motor alterations. The cognitive deficits include disturbances in intellectual functions such as memory and learning. In spite of its high prevalence in western societies, the causes of HE have not yet been clearly established. For this reason, experimental models of HE are used to study this condition. In this work, two experimental models were used, one Type B HE (portacaval shunt) and the other Type C HE (cirrhosis by intoxication with thioacetamide), to evaluate its effect on two tasks of associative learning: two-way active avoidance and step-through passive avoidance. The results show an impediment both in acquisition and retention of active avoidance in both models of HE. However, in passive avoidance, only the rats with portacaval shunt presented a memory deficit for the aversive event. In our opinion, these results can be explained by alterations in the neurotransmission system presented by animals with hepatic insufficiency, which are mainly caused by a rise in cerebral histamine and a dysfunction of the glutamatergic system.

  14. Dynamic modelling and experimental study of asymmetric optothermal microactuator

    NASA Astrophysics Data System (ADS)

    Wang, Shuying; Chun, Qin; You, Qingyang; Wang, Yingda; Zhang, Haijun

    2017-01-01

    This paper reports the dynamic modelling and experimental study of an asymmetric optothermal microactuator (OTMA). According to the principle of thermal flux, a theoretical model for instantaneous temperature distribution of an expansion arm is established and the expression of expansion increment is derived. Dynamic expansion properties of the arm under laser pulse irradiation are theoretically analyzed indicating that both of the maximum expansion and expansion amplitude decrease with the pulse frequency increasing. Experiments have been further carried out on an OTMA fabricated by using an excimer laser micromachining system. It is shown that the OTMA deflects periodically with the same frequency of laser pulse irradiation. Experimental results also prove that both OTMA's maximum deflection and deflection amplitude (related to maximum expansion and expansion amplitude of the arm) decrease as frequency increases, matching with the theoretical model quite well. Even though the OTMA's deflection decrease at higher frequency, it is still capable of generating 8.2 μm maximum deflection and 4.2 μm deflection amplitude under 17 Hz/2 mW laser pulse irradiation. This work improves the potential applications of optothermal microactuators in micro-opto-electro-mechanical system (MOEMS) and micro/nano-technology fields.

  15. Experimental and theoretical models of human cultural evolution.

    PubMed

    Kempe, Marius; Mesoudi, Alex

    2014-05-01

    The modern field of cultural evolution is now over 30 years old, and an extensive body of theory and data has been amassed. This article reviews models of cultural evolution, both experimental and theoretical, and surveys what they can tell us about cultural evolutionary processes. The models are grouped according to which of four broad questions they address: (1) How are cultural traits changed during transmission? (2) How and why do cultural traits accumulate over time? (3) What social learning biases do people use? and (4) What are the population-level consequences of different social learning biases? We conclude by highlighting gaps in the literature and promising future research directions, including the further integration of theoretical models and experimental data, the identification of the factors underlying cumulative cultural evolution, and the explanation of individual and cultural variation in social learning biases. For further resources related to this article, please visit the WIREs website. The authors have declared no conflicts of interest for this article. © 2014 John Wiley & Sons, Ltd.

  16. Neuroinflammatory targets and treatments for epilepsy validated in experimental models.

    PubMed

    Aronica, Eleonora; Bauer, Sebastian; Bozzi, Yuri; Caleo, Matteo; Dingledine, Raymond; Gorter, Jan A; Henshall, David C; Kaufer, Daniela; Koh, Sookyong; Löscher, Wolfgang; Louboutin, Jean-Pierre; Mishto, Michele; Norwood, Braxton A; Palma, Eleonora; Poulter, Michael O; Terrone, Gaetano; Vezzani, Annamaria; Kaminski, Rafal M

    2017-07-01

    A large body of evidence that has accumulated over the past decade strongly supports the role of inflammation in the pathophysiology of human epilepsy. Specific inflammatory molecules and pathways have been identified that influence various pathologic outcomes in different experimental models of epilepsy. Most importantly, the same inflammatory pathways have also been found in surgically resected brain tissue from patients with treatment-resistant epilepsy. New antiseizure therapies may be derived from these novel potential targets. An essential and crucial question is whether targeting these molecules and pathways may result in anti-ictogenesis, antiepileptogenesis, and/or disease-modification effects. Therefore, preclinical testing in models mimicking relevant aspects of epileptogenesis is needed to guide integrated experimental and clinical trial designs. We discuss the most recent preclinical proof-of-concept studies validating a number of therapeutic approaches against inflammatory mechanisms in animal models that could represent novel avenues for drug development in epilepsy. Finally, we suggest future directions to accelerate preclinical to clinical translation of these recent discoveries. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

  17. Experimental dynamic characterizations and modelling of disk vibrations for HDDs.

    PubMed

    Pang, Chee Khiang; Ong, Eng Hong; Guo, Guoxiao; Qian, Hua

    2008-01-01

    Currently, the rotational speed of spindle motors in HDDs (Hard-Disk Drives) are increasing to improve high data throughput and decrease rotational latency for ultra-high data transfer rates. However, the disk platters are excited to vibrate at their natural frequencies due to higher air-flow excitation as well as eccentricities and imbalances in the disk-spindle assembly. These factors contribute directly to TMR (Track Mis-Registration) which limits achievable high recording density essential for future mobile HDDs. In this paper, the natural mode shapes of an annular disk mounted on a spindle motor used in current HDDs are characterized using FEM (Finite Element Methods) analysis and verified with SLDV (Scanning Laser Doppler Vibrometer) measurements. The identified vibration frequencies and amplitudes of the disk ODS (Operating Deflection Shapes) at corresponding disk mode shapes are modelled as repeatable disturbance components for servo compensation in HDDs. Our experimental results show that the SLDV measurements are accurate in capturing static disk mode shapes without the need for intricate air-flow aero-elastic models, and the proposed disk ODS vibration model correlates well with experimental measurements from a LDV.

  18. Size exclusion deep bed filtration: Experimental and modelling uncertainties

    SciTech Connect

    Badalyan, Alexander You, Zhenjiang; Aji, Kaiser; Bedrikovetsky, Pavel; Carageorgos, Themis; Zeinijahromi, Abbas

    2014-01-15

    A detailed uncertainty analysis associated with carboxyl-modified latex particle capture in glass bead-formed porous media enabled verification of the two theoretical stochastic models for prediction of particle retention due to size exclusion. At the beginning of this analysis it is established that size exclusion is a dominant particle capture mechanism in the present study: calculated significant repulsive Derjaguin-Landau-Verwey-Overbeek potential between latex particles and glass beads is an indication of their mutual repulsion, thus, fulfilling the necessary condition for size exclusion. Applying linear uncertainty propagation method in the form of truncated Taylor's series expansion, combined standard uncertainties (CSUs) in normalised suspended particle concentrations are calculated using CSUs in experimentally determined parameters such as: an inlet volumetric flowrate of suspension, particle number in suspensions, particle concentrations in inlet and outlet streams, particle and pore throat size distributions. Weathering of glass beads in high alkaline solutions does not appreciably change particle size distribution, and, therefore, is not considered as an additional contributor to the weighted mean particle radius and corresponded weighted mean standard deviation. Weighted mean particle radius and LogNormal mean pore throat radius are characterised by the highest CSUs among all experimental parameters translating to high CSU in the jamming ratio factor (dimensionless particle size). Normalised suspended particle concentrations calculated via two theoretical models are characterised by higher CSUs than those for experimental data. The model accounting the fraction of inaccessible flow as a function of latex particle radius excellently predicts normalised suspended particle concentrations for the whole range of jamming ratios. The presented uncertainty analysis can be also used for comparison of intra- and inter-laboratory particle size exclusion data.

  19. Size exclusion deep bed filtration: Experimental and modelling uncertainties

    NASA Astrophysics Data System (ADS)

    Badalyan, Alexander; You, Zhenjiang; Aji, Kaiser; Bedrikovetsky, Pavel; Carageorgos, Themis; Zeinijahromi, Abbas

    2014-01-01

    A detailed uncertainty analysis associated with carboxyl-modified latex particle capture in glass bead-formed porous media enabled verification of the two theoretical stochastic models for prediction of particle retention due to size exclusion. At the beginning of this analysis it is established that size exclusion is a dominant particle capture mechanism in the present study: calculated significant repulsive Derjaguin-Landau-Verwey-Overbeek potential between latex particles and glass beads is an indication of their mutual repulsion, thus, fulfilling the necessary condition for size exclusion. Applying linear uncertainty propagation method in the form of truncated Taylor's series expansion, combined standard uncertainties (CSUs) in normalised suspended particle concentrations are calculated using CSUs in experimentally determined parameters such as: an inlet volumetric flowrate of suspension, particle number in suspensions, particle concentrations in inlet and outlet streams, particle and pore throat size distributions. Weathering of glass beads in high alkaline solutions does not appreciably change particle size distribution, and, therefore, is not considered as an additional contributor to the weighted mean particle radius and corresponded weighted mean standard deviation. Weighted mean particle radius and LogNormal mean pore throat radius are characterised by the highest CSUs among all experimental parameters translating to high CSU in the jamming ratio factor (dimensionless particle size). Normalised suspended particle concentrations calculated via two theoretical models are characterised by higher CSUs than those for experimental data. The model accounting the fraction of inaccessible flow as a function of latex particle radius excellently predicts normalised suspended particle concentrations for the whole range of jamming ratios. The presented uncertainty analysis can be also used for comparison of intra- and inter-laboratory particle size exclusion data.

  20. Model reduction for experimental thermal characterization of a holding furnace

    NASA Astrophysics Data System (ADS)

    Loussouarn, Thomas; Maillet, Denis; Remy, Benjamin; Dan, Diane

    2017-09-01

    Vacuum holding induction furnaces are used for the manufacturing of turbine blades by loss wax foundry process. The control of solidification parameters is a key factor for the manufacturing of these parts. The definition of the structure of a reduced heat transfer model with experimental identification through an estimation of its parameters is required here. Internal sensors outputs, together with this model, can be used for assessing the thermal state of the furnace through an inverse approach, for a better control. Here, an axisymmetric furnace and its load have been numerically modelled using FlexPDE, a finite elements code. The internal induction heat source as well as the transient radiative transfer inside the furnace are calculated through this detailed model. A reduced lumped body model has been constructed to represent the numerical furnace. The model reduction and the estimation of the parameters of the lumped body have been made using a Levenberg-Marquardt least squares minimization algorithm, using two synthetic temperature signals with a further validation test.

  1. Experimental and Modeling Studies of High Temperature Combustion.

    DTIC Science & Technology

    1982-06-07

    AD-AI15 908 TEXAS UNIV AT AUSTIN F/6 21/2 EXPERIMENTAL AND MODELING STUDIES OF HIGH TEMPERATURE COM13USTIO-ETC(U) jJUN 82 W C SARDINER OAAG29-78-6...matter, ignition of natural gas-air mixtures presents an explosion hazard that has been studied before in connection with the transi- tion to... can be reason- ably well understood in terms of reaction mechanisms and rate constants repre- sentative of the current state-of-the-art in this field

  2. Hepatitis C Virus Experimental Model Systems and Antiviral drug Research*

    PubMed Central

    Uprichard, Susan L.

    2010-01-01

    An estimated 130 million people worldwide are chronically infected with hepatitis C virus (HCV) making it a leading cause of liver disease worldwide. Because the currently available therapy of pegylated interferon-alpha and ribavirin is only effective in a subset of patients, the development of new HCV antivirals is a healthcare imperative. This review discusses the experimental models available for HCV antiviral drug research, recent advances in HCV antiviral drug development, as well as active research being pursued to facilitate development of new HCV-specific therapeutics. PMID:20960298

  3. Barchan dunes in two dimensions: experimental tests for minimal models.

    PubMed

    Groh, Christopher; Wierschem, Andreas; Aksel, Nuri; Rehberg, Ingo; Kruelle, Christof A

    2008-08-01

    A well-defined two-dimensional single barchan dune under the force of a shearing water flow is investigated experimentally. From an initially prepared triangular heap a rapid relaxation to a steady-state solution is observed with constant mass, shape, and velocity. This attractor exhibits all characteristic features of barchan dunes found in nature, namely a gently inclined windward side, crest, brink, and steep lee face. The relaxation time towards the steady state increases with mass. For small dunes we find significant deviations from a fixed height-length aspect ratio. As predicted by recent theoretical models, the migration velocity scales reciprocal to the length of the dune.

  4. Modeling and experimental diagnostics in polymer electrolyte fuel cells

    NASA Astrophysics Data System (ADS)

    Springer, T. E.; Wilson, M. S.; Gottesfeld, S.

    1993-12-01

    This paper presents a fit between model and experiments for well-humidified polymer electrolyte fuel cells operated to maximum current density with a range of cathode gas compositions. The model considers, in detail, losses caused by: (1) interfacial kinetics at the Pt/ionomer interface; (2) gas-transport and ionic-conductivity limitations in the catalyst layer; and (3) gas-transport limitations in the cathode backing. Our experimental data were collected with cells that utilized thin-film catalyst layers bonded directly to the membrane, and a separate catalyst-free hydrophobic backing layer. This structure allows a clearer resolution of the processes taking place in each of these distinguishable parts of the cathode. In our final comparison of model predictions with the experimental data, we stress the simultaneous fit of a family of complete polarization curves obtained for gas compositions ranging from 5 atoms O2 to a mixture of 5% O2 in N2, employing in each case the same model parameters for interracial kinetics, catalyst-layer transport, and backing-layer transport. This approach allowed us to evaluate losses in the cathode backing and in the cathode catalyst layer, and thus identify the improvements required to enhance the performance of air cathodes in polymer electrolyte fuel cells. Finally, we show that effects of graded depletion in oxygen along the gas flow channel can be accurately modeled using a uniform effective oxygen concentration in the flow channel, equal to the average of inlet and exit concentrations. This approach has enabled simplified and accurate consideration of oxygen utilization effects.

  5. Internally electrodynamic particle model: Its experimental basis and its predictions

    SciTech Connect

    Zheng-Johansson, J. X.

    2010-03-15

    The internally electrodynamic (IED) particle model was derived based on overall experimental observations, with the IED process itself being built directly on three experimental facts: (a) electric charges present with all material particles, (b) an accelerated charge generates electromagnetic waves according to Maxwell's equations and Planck energy equation, and (c) source motion produces Doppler effect. A set of well-known basic particle equations and properties become predictable based on first principles solutions for the IED process; several key solutions achieved are outlined, including the de Broglie phase wave, de Broglie relations, Schroedinger equation, mass, Einstein mass-energy relation, Newton's law of gravity, single particle self interference, and electromagnetic radiation and absorption; these equations and properties have long been broadly experimentally validated or demonstrated. A conditioned solution also predicts the Doebner-Goldin equation which emerges to represent a form of long-sought quantum wave equation including gravity. A critical review of the key experiments is given which suggests that the IED process underlies the basic particle equations and properties not just sufficiently but also necessarily.

  6. An experimental methodology for a fuzzy set preference model

    NASA Technical Reports Server (NTRS)

    Turksen, I. B.; Willson, Ian A.

    1992-01-01

    models and vague linguistic preferences has greatly limited the usefulness and predictive validity of existing preference models. A fuzzy set preference model that uses linguistic variables and a fully interactive implementation should be able to simultaneously address these issues and substantially improve the accuracy of demand estimates. The parallel implementation of crisp and fuzzy conjoint models using identical data not only validates the fuzzy set model but also provides an opportunity to assess the impact of fuzzy set definitions and individual attribute choices implemented in the interactive methodology developed in this research. The generalized experimental tools needed for conjoint models can also be applied to many other types of intelligent systems.

  7. Experimental studies and modeling on concentration polarization in forward osmosis.

    PubMed

    Qin, Jian-Jun; Chen, Sijie; Oo, Maung Htun; Kekre, Kiran A; Cornelissen, Emile R; Ruiken, Chris J

    2010-01-01

    Concentration polarization (CP) is an important issue in forward osmosis (FO) processes and it is believed that the coupled effect of dilutive internal CP (DICP) and concentrative external CP (CECP) limits FO flux. The objective of this study was to distinguish individual contribution of different types of DICP and CECP via modeling and to validate it by pilot studies. The influence of DICP/CECP on FO flux has been investigated in this study. The CP model presented in this work was derived from a previous study and evaluated by bench-scale FO experiments. Experiments were conducted with drinking water as the feed and NaCl/MgSO(4) as draw solutions at different concentrations and velocities. Modeling results indicated that DICP contributed to a flux reduction by 99.9% for 0.5 M NaCl as a draw solution although the flow pattern of both feed and draw solutions was turbulent. DICP could be improved via selection of the draw solution. The modeling results were well fit with the experimental data. It was concluded that the model could be used for selection of the draw solution and prediction of water flux under similar situation. A draw solution with greater diffusion coefficient or a thinner substrate of an asymmetric FO membrane resulted in a higher flux.

  8. Immunology and Homeopathy. 3. Experimental Studies on Animal Models

    PubMed Central

    Bellavite, Paolo; Ortolani, Riccardo; Conforti, Anita

    2006-01-01

    A search of the literature and the experiments carried out by the authors of this review show that there are a number of animal models where the effect of homeopathic dilutions or the principles of homeopathic medicine have been tested. The results relate to the immunostimulation by ultralow doses of antigens, the immunological models of the ‘simile’, the regulation of acute or chronic inflammatory processes and the use of homeopathic medicines in farming. The models utilized by different research groups are extremely etherogeneous and differ as the test medicines, the dilutions and the outcomes are concerned. Some experimental lines, particularly those utilizing mice models of immunomodulation and anti-inflammatory effects of homeopathic complex formulations, give support to a real effect of homeopathic high dilutions in animals, but often these data are of preliminary nature and have not been independently replicated. The evidence emerging from animal models is supporting the traditional ‘simile’ rule, according to which ultralow doses of compounds, that in high doses are pathogenic, may have paradoxically a protective or curative effect. Despite a few encouraging observational studies, the effectiveness of the homeopathic prevention or therapy of infections in veterinary medicine is not sufficiently supported by randomized and controlled trials. PMID:16786046

  9. Friction at seismic slip rates: testing thermal weakening models experimentally

    NASA Astrophysics Data System (ADS)

    Nielsen, S. B.; Spagnuolo, E.; Violay, M.; Di Toro, G.

    2013-12-01

    Recent experiments systematically explore rock friction under crustal earthquake conditions (fast slip rate 1experimental data to test various thermal weakening models (flash weakening, diffusion superplasticity, frictional melt lubrication) and to verify the direct or indirect role of temperature on friction. We show that in the absence of melting and/or pressurization, the weakening transient, the dynamic sliding friction and the restrengthening phase can be explained either by the flash weakening model (Archard, 1958; Rice, 2006; Noda et al., 2009) or by a simple model where the strength of the slip zone is directly controlled by an Arrhenious-like thermal dependance. In the presence of melting, which occurs quite easily in silicatic rocks under coseismic conditions, the data are well explained by the frictional melt model (Nielsen et al., 2008, 2010). Frictional heating is simple to compute but requires a rather costly and inefficient convolution (even with the use of FFT) for a dynamic, extended fault simulation. Hence we desing an efficient and accurate wavenumber approximation for a solution of the temperature evolution on the fault. Finally, we propose a compact and paractical model based on a small number of memory variables for the implementation of thermal weakening friction in seismic fault simulations.

  10. Maternal hypothyroidism: An overview of current experimental models.

    PubMed

    Ghanbari, Mahboubeh; Ghasemi, Asghar

    2017-08-11

    Maternal hypothyroidism (MH) is the most common cause of transient congenital hypothyroidism. Different animal models are used for assessing developmental effects of MH in offspring. The severity and status of hypothyroidism in animal models must be a reflection of the actual conditions in humans. To obtain comparable results with different clinical conditions, which lead to MH in humans, several factors have been suggested for researchers to consider before designing the experimental models. Regarding development of fetal body systems during pregnancy, interference at different times provides different results and the appropriate time for induction of hypothyroidism should be selected based on accurate time of development of the system under assessment. Other factors that should be taken into consideration include, physiological and biochemical differences between humans and other species, thyroid hormone-independent effects of anti-thyroid drugs, circadian rhythms in TSH secretion, sex differences, physical and psychological stress. This review addresses essential guidelines for selecting and managing the optimal animal model for MH as well as discussing the pros and cons of currently used models. Copyright © 2017. Published by Elsevier Inc.

  11. Elastase-induced pulmonary emphysema: insights from experimental models.

    PubMed

    Antunes, Mariana A; Rocco, Patricia R M

    2011-12-01

    Several distinct stimuli can be used to reproduce histological and functional features of human emphysema, a leading cause of disability and death. Since cigarette smoke is the main cause of emphysema in humans, experimental researches have attempted to reproduce this situation. However, this is an expensive and cumbersome method of emphysema induction, and simpler, more efficacious alternatives have been sought. Among these approaches, elastolytic enzymes have been widely used to reproduce some characteristics of human cigarette smoke-induced disease, such as: augmentation of airspaces, inflammatory cell influx into the lungs, and systemic inflammation. Nevertheless, the use of elastase-induced emphysema models is still controversial, since the disease pathways involved in elastase induction may differ from those occurring in smoke-induced emphysema. This indicates that the choice of an emphysema model may impact the results of new therapies or drugs being tested. The aim of this review is to compare the mechanisms of disease induction in smoke and elastase emphysema models, to describe the differences among various elastase models, and to establish the advantages and disadvantages of elastase-induced emphysema models. More studies are required to shed light on the mechanisms of elastase-induced emphysema.

  12. Experimental investigation and model development for a harmonic drive transmission.

    SciTech Connect

    Preissner, C.; Shu, D.; Royston, T. J.; Univ. of Illinois at Chicago

    2007-01-01

    Harmonic drive transmissions (HDTs) are compact, low-backlash, high-ratio, high-resolution rotary motion transmissions. One application to benefit from these attributes is the revolute joint robot. Engineers at the Advanced Photon Source (APS) are investigating the use of this type of robot for the positioning of an x-ray detector; understanding the properties of the robot components is crucial to modeling positioner behavior. The robot bearing elements had been investigated previously, leaving the transmission as the missing component. While the benefits of HDTs are well known, the disadvantages, including fluctuating dissipation characteristics and nonlinear stiffness, are not understood as well. These characteristics can contribute uncontrolled dynamics to the overall robot performance. A dynamometer has been constructed at the APS to experimentally measure the HDT's response. Empirical torque and position data were recorded for multiple transmission load cases and input conditions. In turn, a computer model of the dynamometer HDT system was constructed to approximate the observed response.

  13. Wake redirection: comparison of analytical, numerical and experimental models

    NASA Astrophysics Data System (ADS)

    Wang, Jiangang; Bottasso, Carlo L.; Campagnolo, Filippo

    2016-09-01

    This paper focuses on wake redirection techniques for wind farm control. Two control strategies are investigated: yaw misalignment and cyclic pitch control. First, analytical formulas are derived for both techniques, with the goal of providing a simple physical interpretation of the behavior of the two methods. Next, more realistic results are obtained by numerical simulations performed with CFD and by experiments conducted with scaled wind turbine models operating in a boundary layer wind tunnel. Comparing the analytical, numerical and experimental models allows for a cross-validation of the results and a better understanding of the two wake redirection techniques. Results indicate that yaw misalignment is more effective than cyclic pitch control in displacing the wake laterally, although the latter may have positive effects on wake recovery.

  14. Astrocyte regulation of sleep circuits: experimental and modeling perspectives

    PubMed Central

    Fellin, Tommaso; Ellenbogen, Jeffery M.; De Pittà, Maurizio; Ben-Jacob, Eshel; Halassa, Michael M.

    2012-01-01

    Integrated within neural circuits, astrocytes have recently been shown to modulate brain rhythms thought to mediate sleep function. Experimental evidence suggests that local impact of astrocytes on single synapses translates into global modulation of neuronal networks and behavior. We discuss these findings in the context of current conceptual models of sleep generation and function, each of which have historically focused on neural mechanisms. We highlight the implications and the challenges introduced by these results from a conceptual and computational perspective. We further provide modeling directions on how these data might extend our knowledge of astrocytic properties and sleep function. Given our evolving understanding of how local cellular activities during sleep lead to functional outcomes for the brain, further mechanistic and theoretical understanding of astrocytic contribution to these dynamics will undoubtedly be of great basic and translational benefit. PMID:22973222

  15. Performance Modeling of an Experimental Laser Propelled Lightcraft

    NASA Technical Reports Server (NTRS)

    Wang, Ten-See; Chen, Yen-Sen; Liu, Jiwen; Myrabo, Leik N.; Mead, Franklin B., Jr.

    2000-01-01

    A computational plasma aerodynamics model is developed to study the performance of an experimental laser propelled lightcraft. The computational methodology is based on a time-accurate, three-dimensional, finite-difference, chemically reacting, unstructured grid, pressure- based formulation. The underlying physics are added and tested systematically using a building-block approach. The physics modeled include non-equilibn'um thermodynamics, non-equilibrium air-plasma finite-rate kinetics, specular ray tracing, laser beam energy absorption and equi refraction by plasma, non-equilibrium plasma radiation, and plasma resonance. A series of transient computations are performed at several laser pulse energy levels and the simulated physics are discussed and compared with those of tests and literature. The predicted coupling coefficients for the lightcraft compared reasonably well with those of tests conducted on a pendulum apparatus.

  16. Experimental platynosomosis: Characterization of parasite development in the mouse model.

    PubMed

    Pinto, Hudson A; Mati, Vitor L T; Melo, Alan L

    2015-06-30

    Despite the veterinary importance of species of Platynosomum, biliary trematode parasites of birds and mammals with worldwide distribution and a growing role in feline practice, the basic parasitological aspects of platynosomosis is still not completely understood due to the scarcity of studies in experimental models. In the present study, metacercariae of Platynosomum illiciens obtained from naturally infected tropical house geckos (Hemidactylus mabouia) in an urban area of Brazil were force-fed to mice of the AKR/J strain (100 metacercariae/animal). Groups of mice were euthanized at 60, 120, 160 and 240 days post-infection (DPI), and the biliary tree of the animals (intrahepatic biliary ducts, common hepatic and bile ducts, cystic duct and gallbladder) were examined for the presence of adult parasites. Recovered flukes were counted, classified by their site of origin (i.e., intrahepatic or extrahepatic biliary ducts) and morphologically analyzed under light microscope. The number of adult parasites obtained at 60, 120, 160 and 240 DPI was 22 ± 6 (16-32), 41 ± 14 (18-48), 27 ± 11 (18-40) and 20 ± 6 (13-30), respectively, and no significant differences in total worm burden at the different experimental times were observed. However, 41%, 51%, 75% and 95% of the parasites were found in the common hepatic and bile ducts at 60, 120, 160 and 240 DPI, respectively, suggesting the occurrence of parasitic migration to the extrahepatic biliary tree during infection; however, no parasites were observed in the gallbladder or cystic duct. Regarding the morphometric analysis, progressive growth of P. illiciens during the experimental time was observed, and the parasites collected from the extrahepatic bile ducts were larger than those obtained from the intrahepatic ducts at the same time of infection. Parasites obtained from the extrahepatic biliary tree of the mice at 160 DPI had similar measurements to those of parasites obtained at 240 DPI, and those measurements were

  17. Contaminant plume configuration and movement: an experimental model

    NASA Astrophysics Data System (ADS)

    Alencoao, A.; Reis, A.; Pereira, M. G.; Liberato, M. L. R.; Caramelo, L.; Amraoui, M.; Amorim, V.

    2009-04-01

    The relevance of Science and Technology in our daily routines makes it compulsory to educate citizens who have both scientific literacy and scientific knowledge. These will allow them to be intervening citizens in a constantly changing society. Thus, physical and natural sciences are included in school curricula, both in primary and secondary education, with the fundamental aim of developing in the students the skills, attitudes and knowledge needed for the understanding of the planet Earth and its real problems. On the other hand, teaching in Geosciences is more and more based on practical methodologies which use didactic material, sustaining teachers' pedagogical practices and facilitating students' learning tasks suggested on the syllabus defined for each school level. Themes related to exploring the different components of the Hydrological Cycle and themes related to natural environment protection and preservation, namely water resources and soil contamination by industrial and urban sewage are examples of subject matters included on the Portuguese syllabus. These topics motivated the conception and construction of experimental models for the study of the propagation of pollutants on a porous medium. The experimental models allow inducing a horizontal flux of water though different kinds of permeable substances (e.g. sand, silt), with contamination spots on its surface. These experimental activities facilitate the student to understand the flow path of contaminating substances on the saturated zone and to observe the contaminant plume configuration and movement. The activities are explored in a teaching and learning process perspective where the student builds its own knowledge through real question- problem based learning which relate Science, Technology and Society. These activities have been developed in the framework of project ‘Water in the Environment' (CV/PVI/0854) of the POCTI Program (Programa Operacional "Ciência, Tecnologia, Inovação") financed

  18. Adequacy of ovarian diathermy under ultrasound control: an experimental model

    PubMed Central

    2013-01-01

    Background To develop a minimally invasive ovarian cauterization technique under transvaginal ultrasound control and evaluate the safety and feasability of monopolar cauterization to cause ovarian injury using female cattle of reproductive age as an experimental model. Method Experimental study in a university research center was performed. Eleven female bovines of reproductive age were submitted to monopolar transvaginal ovarian cauterization. The right ovary (RO) was punctured at four sites and 40 W was applied for 5 s at each point, resulting in a total of 800 J (Joules) of thermal energy. In the left ovary (LO), the procedure was similar, with the same time and 80 W, resulting in a thermal energy of 1600 J. Macroscopic and microscopic lesions were assessed. Results Of 22 ovaries punctured, 20 were cauterized and exhibited macroscopic and typical microscopic lesions. No lesions could be found in the needle path. The measures of the areas of microscopic electrocautery lesions calculated estimating a cylindrical volume showed a median of 1.12% in the right ovary and 1.65% in the left ovary. When the estimate was calculated by spherical shape, the medians were 1.77% in the right ovary and 3.06% in the left ovary. There was a statistically significant difference in these two estimates (sphere, p = 0.008; cylinder, p = 0.021). Conclusion The experimental animal model described for transvaginal ultrasound-guided ovarian needle cauterization seems to be feasible. The ovaries were successfully cauterized without injuries in needle path and more energy resulted in significantly more thermal lesion. The safety and effectiveness of this technique, theoretically less invasive than current ovarian drilling methods, could be tested in anovulatory women with PCOS. PMID:23886295

  19. Adequacy of ovarian diathermy under ultrasound control: an experimental model.

    PubMed

    Pimentel, Anita Mylius; Kliemann, Lucia Maria; Brum, Daniela Dos Santos; Leivas, Fábio Gallas; Sanches, Paulo Roberto Stefani; Capp, Edison; Corleta, Helena von Eye

    2013-01-01

    To develop a minimally invasive ovarian cauterization technique under transvaginal ultrasound control and evaluate the safety and feasability of monopolar cauterization to cause ovarian injury using female cattle of reproductive age as an experimental model. Experimental study in a university research center was performed. Eleven female bovines of reproductive age were submitted to monopolar transvaginal ovarian cauterization. The right ovary (RO) was punctured at four sites and 40 W was applied for 5 s at each point, resulting in a total of 800 J (Joules) of thermal energy. In the left ovary (LO), the procedure was similar, with the same time and 80 W, resulting in a thermal energy of 1600 J. Macroscopic and microscopic lesions were assessed. Of 22 ovaries punctured, 20 were cauterized and exhibited macroscopic and typical microscopic lesions. No lesions could be found in the needle path. The measures of the areas of microscopic electrocautery lesions calculated estimating a cylindrical volume showed a median of 1.12% in the right ovary and 1.65% in the left ovary. When the estimate was calculated by spherical shape, the medians were 1.77% in the right ovary and 3.06% in the left ovary. There was a statistically significant difference in these two estimates (sphere, p = 0.008; cylinder, p = 0.021). The experimental animal model described for transvaginal ultrasound-guided ovarian needle cauterization seems to be feasible. The ovaries were successfully cauterized without injuries in needle path and more energy resulted in significantly more thermal lesion. The safety and effectiveness of this technique, theoretically less invasive than current ovarian drilling methods, could be tested in anovulatory women with PCOS.

  20. Spatiotemporal properties of microsaccades: Model predictions and experimental tests

    NASA Astrophysics Data System (ADS)

    Zhou, Jian-Fang; Yuan, Wu-Jie; Zhou, Zhao

    2016-10-01

    Microsaccades are involuntary and very small eye movements during fixation. Recently, the microsaccade-related neural dynamics have been extensively investigated both in experiments and by constructing neural network models. Experimentally, microsaccades also exhibit many behavioral properties. It’s well known that the behavior properties imply the underlying neural dynamical mechanisms, and so are determined by neural dynamics. The behavioral properties resulted from neural responses to microsaccades, however, are not yet understood and are rarely studied theoretically. Linking neural dynamics to behavior is one of the central goals of neuroscience. In this paper, we provide behavior predictions on spatiotemporal properties of microsaccades according to microsaccade-induced neural dynamics in a cascading network model, which includes both retinal adaptation and short-term depression (STD) at thalamocortical synapses. We also successfully give experimental tests in the statistical sense. Our results provide the first behavior description of microsaccades based on neural dynamics induced by behaving activity, and so firstly link neural dynamics to behavior of microsaccades. These results indicate strongly that the cascading adaptations play an important role in the study of microsaccades. Our work may be useful for further investigations of the microsaccadic behavioral properties and of the underlying neural dynamical mechanisms responsible for the behavioral properties.

  1. Taenia solium: Development of an Experimental Model of Porcine Neurocysticercosis

    PubMed Central

    Fleury, Agnès; Trejo, Armando; Cisneros, Humberto; García-Navarrete, Roberto; Villalobos, Nelly; Hernández, Marisela; Villeda Hernández, Juana; Hernández, Beatriz; Rosas, Gabriela; Bobes, Raul J.; S. de Aluja, Aline; Sciutto, Edda; Fragoso, Gladis

    2015-01-01

    Human neurocysticercosis (NC) is caused by the establishment of Taenia solium larvae in the central nervous system. NC is a severe disease still affecting the population in developing countries of Latin America, Asia, and Africa. While great improvements have been made on NC diagnosis, treatment, and prevention, the management of patients affected by extraparenchymal parasites remains a challenge. The development of a T. solium NC experimental model in pigs that will allow the evaluation of new therapeutic alternatives is herein presented. Activated oncospheres (either 500 or 1000) were surgically implanted in the cerebral subarachnoid space of piglets. The clinical status and the level of serum antibodies in the animals were evaluated for a 4-month period after implantation. The animals were sacrificed, cysticerci were counted during necropsy, and both the macroscopic and microscopic characteristics of cysts were described. Based on the number of established cysticerci, infection efficiency ranged from 3.6% (1000 oncospheres) to 5.4% (500 oncospheres). Most parasites were caseous or calcified (38/63, 60.3%) and were surrounded by an exacerbated inflammatory response with lymphocyte infiltration and increased inflammatory markers. The infection elicited specific antibodies but no neurological signs. This novel experimental model of NC provides a useful tool to evaluate new cysticidal and anti-inflammatory approaches and it should improve the management of severe NC patients, refractory to the current treatments. PMID:26252878

  2. The KSR1: Experimentation and modeling of poststore

    SciTech Connect

    Rosti, E.; Smirni, E.; Wagner, T.D.; Apon, A.W.; Dowdy, L.W.

    1993-02-01

    Kendall Square Research introduced the KSR1 system in 1991. The architecture is based on a ring of rings of 64-bit microprocessors. It is a distributed, shared memory system and is scalable. The memory structure is unique and is the key to understanding the system. Different levels of caching eliminates physical memory addressing and leads to the ALLCACHE{trademark} scheme. Since requested data may be found in any of several caches, the initial access time is variable. Once pulled into the local (sub)cache, subsequent access times are fixed and minimal. Thus, the KSR1 is a Cache-Only Memory Architecture (COMA) system.This paper describes experimentation and an analytic model of the KSR1. The focus is on the poststore programmer option. With the poststore option, the programmer can elect to broadcast the updated value of a variable to all processors that might have a copy. This may save time for threads on other processors, but delays the broadcasting thread and places additional traffic on the ring. The specific issue addressed is to determine under what conditions poststore is beneficial. The analytic model and the experimental observations are in good agreement. They indicate that the decision to use poststore depends both on the application and the current system load.

  3. The KSR1: Experimentation and modeling of poststore

    SciTech Connect

    Rosti, E. . Dipt. di Scienze dell'Informazione); Smirni, E.; Wagner, T.D.; Apon, A.W.; Dowdy, L.W. . Dept. of Computer Science)

    1993-02-01

    Kendall Square Research introduced the KSR1 system in 1991. The architecture is based on a ring of rings of 64-bit microprocessors. It is a distributed, shared memory system and is scalable. The memory structure is unique and is the key to understanding the system. Different levels of caching eliminates physical memory addressing and leads to the ALLCACHE[trademark] scheme. Since requested data may be found in any of several caches, the initial access time is variable. Once pulled into the local (sub)cache, subsequent access times are fixed and minimal. Thus, the KSR1 is a Cache-Only Memory Architecture (COMA) system.This paper describes experimentation and an analytic model of the KSR1. The focus is on the poststore programmer option. With the poststore option, the programmer can elect to broadcast the updated value of a variable to all processors that might have a copy. This may save time for threads on other processors, but delays the broadcasting thread and places additional traffic on the ring. The specific issue addressed is to determine under what conditions poststore is beneficial. The analytic model and the experimental observations are in good agreement. They indicate that the decision to use poststore depends both on the application and the current system load.

  4. [Osteochodral lesion mouse model: an alternative for experimental work].

    PubMed

    Martinez, R; Figueroa, D; Calvo, R; Conget, P; Gallegos, M; Figueroa, F; Ahumada, X

    2015-01-01

    To report a reproducible and inexpensive model of critical osteochondral lesion (LOC) in adult mice for experimental studies An experimental study was conducted on 20 BKS mice of 15 weeks old, in which a LOC of 0.5mm in diameter was made in the trochlear groove. Ten animals were sacrificed at day 7, and the other 10 animals at day 14 of follow up. To assess the ability of the animal to repair/regenerate, a histological analysis was performed using hematoxylin-eosin and safranin-O stains, and the results were evaluated by the ICRS scale using areas of healthy cartilage from the same joint as control. The Mann-Whitney U test was used for the statistical analyses of scores (averages). Significant differences were found in days 7 and 14 between the LOC area and control areas, but no differences were found between the day 7 and day 14. This model of LOC in the trochlear groove of adult mice is highly reproducible, and could be used in further studies to obtain better treatments for chondral pathologies. Copyright © 2014 SECOT. Published by Elsevier Espana. All rights reserved.

  5. Collagen V nasal tolerance in experimental model of systemic sclerosis.

    PubMed

    Velosa, Ana Paula Pereira; Teodoro, Walcy Rosolia; de Oliveira, Cristiane Carla; Dos Santos Filho, Antonio; Moutinho, Rodnei Francisco; Santos, Angela Gomes; Vendramini, Margarete Borges Galhardo; Bueno, Cleonice; Parra, Edwin Roger; Capelozzi, Vera Luiza; Yoshinari, Natalino Hajime

    2007-07-01

    Our aim was to study skin remodeling and autoantibody production in an experimental model of scleroderma (SSc), following nasal tolerance with human type V collagen (Col V). Female New Zealand rabbits (n = 12) were immunized with two doses of 1 mg/ml of Col V in complete Freund's adjuvant and additional two boosters in incomplete Freund's adjuvant to induce SSc. After 150 days, half of these immunized rabbits were submitted to type V collagen-induced tolerance receiving a daily nasal administration of 25 mug of Col V. Control animals (n = 6) were only submitted to type V collagen-induced tolerance. Serial skin biopsies were performed on days 0, 150 and 210, and stained with H&E, Masson's trichrome and Picrosirius for morphological and morphometric analysis. Types I, III and V collagen were identified by immunofluorescence. The animals' serum samples were collected to determine anti types I, III, IV and V collagen and antinuclear antibodies (ANA). Skin biopsies from immunized animals confirmed SSc morphology as previously described, such as progressive decrease of papillary dermis, appendages atrophy, increased type I, III and V collagen deposition. Rabbits with Col V-induced nasal tolerance showed reduction of skin involvement, with significant decrease of collagen amount. Humoral immune response did not change with nasal tolerance. Collagen V nasal tolerance promotes regression of skin remodeling process in an experimental model of SSc. We suggest that nasal tolerance with type V collagen can be a promising therapeutic option to treat scleroderma patients.

  6. Taenia solium: Development of an Experimental Model of Porcine Neurocysticercosis.

    PubMed

    Fleury, Agnès; Trejo, Armando; Cisneros, Humberto; García-Navarrete, Roberto; Villalobos, Nelly; Hernández, Marisela; Villeda Hernández, Juana; Hernández, Beatriz; Rosas, Gabriela; Bobes, Raul J; de Aluja, Aline S; Sciutto, Edda; Fragoso, Gladis

    2015-01-01

    Human neurocysticercosis (NC) is caused by the establishment of Taenia solium larvae in the central nervous system. NC is a severe disease still affecting the population in developing countries of Latin America, Asia, and Africa. While great improvements have been made on NC diagnosis, treatment, and prevention, the management of patients affected by extraparenchymal parasites remains a challenge. The development of a T. solium NC experimental model in pigs that will allow the evaluation of new therapeutic alternatives is herein presented. Activated oncospheres (either 500 or 1000) were surgically implanted in the cerebral subarachnoid space of piglets. The clinical status and the level of serum antibodies in the animals were evaluated for a 4-month period after implantation. The animals were sacrificed, cysticerci were counted during necropsy, and both the macroscopic and microscopic characteristics of cysts were described. Based on the number of established cysticerci, infection efficiency ranged from 3.6% (1000 oncospheres) to 5.4% (500 oncospheres). Most parasites were caseous or calcified (38/63, 60.3%) and were surrounded by an exacerbated inflammatory response with lymphocyte infiltration and increased inflammatory markers. The infection elicited specific antibodies but no neurological signs. This novel experimental model of NC provides a useful tool to evaluate new cysticidal and anti-inflammatory approaches and it should improve the management of severe NC patients, refractory to the current treatments.

  7. Modeling methods for merging computational and experimental aerodynamic pressure data

    NASA Astrophysics Data System (ADS)

    Haderlie, Jacob C.

    This research describes a process to model surface pressure data sets as a function of wing geometry from computational and wind tunnel sources and then merge them into a single predicted value. The described merging process will enable engineers to integrate these data sets with the goal of utilizing the advantages of each data source while overcoming the limitations of both; this provides a single, combined data set to support analysis and design. The main challenge with this process is accurately representing each data source everywhere on the wing. Additionally, this effort demonstrates methods to model wind tunnel pressure data as a function of angle of attack as an initial step towards a merging process that uses both location on the wing and flow conditions (e.g., angle of attack, flow velocity or Reynold's number) as independent variables. This surrogate model of pressure as a function of angle of attack can be useful for engineers that need to predict the location of zero-order discontinuities, e.g., flow separation or normal shocks. Because, to the author's best knowledge, there is no published, well-established merging method for aerodynamic pressure data (here, the coefficient of pressure Cp), this work identifies promising modeling and merging methods, and then makes a critical comparison of these methods. Surrogate models represent the pressure data for both data sets. Cubic B-spline surrogate models represent the computational simulation results. Machine learning and multi-fidelity surrogate models represent the experimental data. This research compares three surrogates for the experimental data (sequential--a.k.a. online--Gaussian processes, batch Gaussian processes, and multi-fidelity additive corrector) on the merits of accuracy and computational cost. The Gaussian process (GP) methods employ cubic B-spline CFD surrogates as a model basis function to build a surrogate model of the WT data, and this usage of the CFD surrogate in building the WT

  8. Integral Reactor Containment Condensation Model and Experimental Validation

    SciTech Connect

    Wu, Qiao; Corradini, Michael

    2016-05-02

    This NEUP funded project, NEUP 12-3630, is for experimental, numerical and analytical studies on high-pressure steam condensation phenomena in a steel containment vessel connected to a water cooling tank, carried out at Oregon State University (OrSU) and the University of Wisconsin at Madison (UW-Madison). In the three years of investigation duration, following the original proposal, the planned tasks have been completed: (1) Performed a scaling study for the full pressure test facility applicable to the reference design for the condensation heat transfer process during design basis accidents (DBAs), modified the existing test facility to route the steady-state secondary steam flow into the high pressure containment for controllable condensation tests, and extended the operations at negative gage pressure conditions (OrSU). (2) Conducted a series of DBA and quasi-steady experiments using the full pressure test facility to provide a reliable high pressure condensation database (OrSU). (3) Analyzed experimental data and evaluated condensation model for the experimental conditions, and predicted the prototypic containment performance under accidental conditions (UW-Madison). A film flow model was developed for the scaling analysis, and the results suggest that the 1/3 scaled test facility covers large portion of laminar film flow, leading to a lower average heat transfer coefficient comparing to the prototypic value. Although it is conservative in reactor safety analysis, the significant reduction of heat transfer coefficient (50%) could under estimate the prototypic condensation heat transfer rate, resulting in inaccurate prediction of the decay heat removal capability. Further investigation is thus needed to quantify the scaling distortion for safety analysis code validation. Experimental investigations were performed in the existing MASLWR test facility at OrST with minor modifications. A total of 13 containment condensation tests were conducted for pressure

  9. Toxin-Induced Experimental Models of Learning and Memory Impairment.

    PubMed

    More, Sandeep Vasant; Kumar, Hemant; Cho, Duk-Yeon; Yun, Yo-Sep; Choi, Dong-Kug

    2016-09-01

    Animal models for learning and memory have significantly contributed to novel strategies for drug development and hence are an imperative part in the assessment of therapeutics. Learning and memory involve different stages including acquisition, consolidation, and retrieval and each stage can be characterized using specific toxin. Recent studies have postulated the molecular basis of these processes and have also demonstrated many signaling molecules that are involved in several stages of memory. Most insights into learning and memory impairment and to develop a novel compound stems from the investigations performed in experimental models, especially those produced by neurotoxins models. Several toxins have been utilized based on their mechanism of action for learning and memory impairment such as scopolamine, streptozotocin, quinolinic acid, and domoic acid. Further, some toxins like 6-hydroxy dopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and amyloid-β are known to cause specific learning and memory impairment which imitate the disease pathology of Parkinson's disease dementia and Alzheimer's disease dementia. Apart from these toxins, several other toxins come under a miscellaneous category like an environmental pollutant, snake venoms, botulinum, and lipopolysaccharide. This review will focus on the various classes of neurotoxin models for learning and memory impairment with their specific mechanism of action that could assist the process of drug discovery and development for dementia and cognitive disorders.

  10. Esophageal aerodynamics in an idealized experimental model of tracheoesophageal speech

    NASA Astrophysics Data System (ADS)

    Erath, Byron D.; Hemsing, Frank S.

    2016-03-01

    Flow behavior is investigated in the esophageal tract in an idealized experimental model of tracheoesophageal speech. The tracheoesophageal prosthesis is idealized as a first-order approximation using a straight, constant diameter tube. The flow is scaled according to Reynolds, Strouhal, and Euler numbers to ensure dynamic similarity. Flow pulsatility is produced by a driven orifice that approximates the kinematics of the pharyngoesophageal segment during tracheoesophageal speech. Particle image velocimetry data are acquired in three orthogonal planes as the flow exits the model prosthesis and enters the esophageal tract. Contrary to prior investigations performed in steady flow with the prosthesis oriented in-line with the flow direction, the fluid dynamics are shown to be highly unsteady, suggesting that the esophageal pressure field will be similarly complex. A large vortex ring is formed at the inception of each phonatory cycle, followed by the formation of a persistent jet. This vortex ring appears to remain throughout the entire cycle due to the continued production of vorticity resulting from entrainment between the prosthesis jet and the curved esophageal walls. Mean flow in the axial direction of the esophagus produces significant stretching of the vortex throughout the phonatory cycle. The stagnation point created by the jet impinging on the esophageal wall varies throughout the cycle due to fluctuations in the jet trajectory, which most likely arises due to flow separation within the model prosthesis. Applications to tracheoesophageal speech, including shortcomings of the model and proposed future plans, are discussed.

  11. The Non-Human Primate Experimental Glaucoma Model

    PubMed Central

    Burgoyne, Claude F.

    2015-01-01

    The purpose of this report is to summarize the current strengths and weaknesses of the non-human primate (NHP) experimental glaucoma (EG) model through sections devoted to its history, methods, important findings, alternative optic neuropathy models and future directions. NHP EG has become well established for studying human glaucoma in part because the NHP optic nerve head (ONH) shares a close anatomic association with the human ONH and because it provides the only means of systematically studying the very earliest visual system responses to chronic IOP elevation, i.e. the conversion from ocular hypertension to glaucomatous damage. However, NHPs are impractical for studies that require large animal numbers, demonstrate spontaneous glaucoma only rarely, do not currently provide a model of the neuropathy at normal levels of IOP, and cannot easily be genetically manipulated, except through tissue-specific, viral vectors. The goal of this summary is to direct NHP EG and non-NHP EG investigators to the previous, current and future accomplishment of clinically relevant knowledge in this model. PMID:26070984

  12. Toxicity of Nanoparticles and an Overview of Current Experimental Models

    PubMed Central

    Bahadar, Haji; Maqbool, Faheem; Niaz, Kamal; Abdollahi, Mohammad

    2016-01-01

    Nanotechnology is a rapidly growing field having potential applications in many areas. Nanoparticles (NPs) have been studied for cell toxicity, immunotoxicity, and genotoxicity. Tetrazolium-based assays such as MTT, MTS, and WST-1 are used to determine cell viability. Cell inflammatory response induced by NPs is checked by measuring inflammatory biomarkers, such as IL-8, IL-6, and tumor necrosis factor, using ELISA. Lactate dehydrogenase (LDH) assay is used for cell membrane integrity. Different types of cell cultures, including cancer cell lines have been employed as in vitro toxicity models. It has been generally agreed that NPs interfere with either assay materials or with detection systems. So far, toxicity data generated by employing such models are conflicting and inconsistent. Therefore, on the basis of available experimental models, it may be difficult to judge and list some of the more valuable NPs as more toxic to biological systems and vice versa. Considering the potential applications of NPs in many fields and the growing apprehensions of FDA about the toxic potential of nanoproducts, it is the need of the hour to look for new internationally agreed free of bias toxicological models by focusing more on in vivo studies. PMID:26286636

  13. Toxin-Induced Experimental Models of Learning and Memory Impairment

    PubMed Central

    More, Sandeep Vasant; Kumar, Hemant; Cho, Duk-Yeon; Yun, Yo-Sep; Choi, Dong-Kug

    2016-01-01

    Animal models for learning and memory have significantly contributed to novel strategies for drug development and hence are an imperative part in the assessment of therapeutics. Learning and memory involve different stages including acquisition, consolidation, and retrieval and each stage can be characterized using specific toxin. Recent studies have postulated the molecular basis of these processes and have also demonstrated many signaling molecules that are involved in several stages of memory. Most insights into learning and memory impairment and to develop a novel compound stems from the investigations performed in experimental models, especially those produced by neurotoxins models. Several toxins have been utilized based on their mechanism of action for learning and memory impairment such as scopolamine, streptozotocin, quinolinic acid, and domoic acid. Further, some toxins like 6-hydroxy dopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and amyloid-β are known to cause specific learning and memory impairment which imitate the disease pathology of Parkinson’s disease dementia and Alzheimer’s disease dementia. Apart from these toxins, several other toxins come under a miscellaneous category like an environmental pollutant, snake venoms, botulinum, and lipopolysaccharide. This review will focus on the various classes of neurotoxin models for learning and memory impairment with their specific mechanism of action that could assist the process of drug discovery and development for dementia and cognitive disorders. PMID:27598124

  14. Desorption isotherms for fresh beef: an experimental and modeling approach.

    PubMed

    Ahmat, Tom; Bruneau, Denis; Kuitche, Alexis; Waste Aregba, Aworou

    2014-04-01

    Desorption isotherms for fresh beef were determined at 30, 40 and 50°C by the static gravimetric method. The resulting isotherms exhibited a type II sigmoid shape. The BET, GAB and Halsey models were used to fit these experimental data. The GAB model was most accurate for all temperatures and all levels of water activity, followed by the BET and Halsey models. The temperature dependence of GAB constants was estimated. The isosteric heat of desorption and its evolution in relation to moisture content were calculated using Clausius-Clapeyron equations. The monolayer moisture content was determined using the GAB model: it decreased as the temperature increased. The density of bound water, the number of adsorption sites, the sorption surface area and the percentage of bound water were calculated using the Caurie equation: all these quantities decreased as the temperature increased. The Kelvin and Halsey equations were used for calculation of pore size, which increases with an increase in moisture levels and sorption temperature.

  15. Toxicity of Nanoparticles and an Overview of Current Experimental Models.

    PubMed

    Bahadar, Haji; Maqbool, Faheem; Niaz, Kamal; Abdollahi, Mohammad

    2016-01-01

    Nanotechnology is a rapidly growing field having potential applications in many areas. Nanoparticles (NPs) have been studied for cell toxicity, immunotoxicity, and genotoxicity. Tetrazolium-based assays such as MTT, MTS, and WST-1 are used to determine cell viability. Cell inflammatory response induced by NPs is checked by measuring inflammatory biomarkers, such as IL-8, IL-6, and tumor necrosis factor, using ELISA. Lactate dehydrogenase (LDH) assay is used for cell membrane integrity. Different types of cell cultures, including cancer cell lines have been employed as in vitro toxicity models. It has been generally agreed that NPs interfere with either assay materials or with detection systems. So far, toxicity data generated by employing such models are conflicting and inconsistent. Therefore, on the basis of available experimental models, it may be difficult to judge and list some of the more valuable NPs as more toxic to biological systems and vice versa. Considering the potential applications of NPs in many fields and the growing apprehensions of FDA about the toxic potential of nanoproducts, it is the need of the hour to look for new internationally agreed free of bias toxicological models by focusing more on in vivo studies.

  16. Autonomous learning derived from experimental modeling of physical laws.

    PubMed

    Grabec, Igor

    2013-05-01

    This article deals with experimental description of physical laws by probability density function of measured data. The Gaussian mixture model specified by representative data and related probabilities is utilized for this purpose. The information cost function of the model is described in terms of information entropy by the sum of the estimation error and redundancy. A new method is proposed for searching the minimum of the cost function. The number of the resulting prototype data depends on the accuracy of measurement. Their adaptation resembles a self-organized, highly non-linear cooperation between neurons in an artificial NN. A prototype datum corresponds to the memorized content, while the related probability corresponds to the excitability of the neuron. The method does not include any free parameters except objectively determined accuracy of the measurement system and is therefore convenient for autonomous execution. Since representative data are generally less numerous than the measured ones, the method is applicable for a rather general and objective compression of overwhelming experimental data in automatic data-acquisition systems. Such compression is demonstrated on analytically determined random noise and measured traffic flow data. The flow over a day is described by a vector of 24 components. The set of 365 vectors measured over one year is compressed by autonomous learning to just 4 representative vectors and related probabilities. These vectors represent the flow in normal working days and weekends or holidays, while the related probabilities correspond to relative frequencies of these days. This example reveals that autonomous learning yields a new basis for interpretation of representative data and the optimal model structure.

  17. Mass Spectrometry Analysis of Hepcidin Peptides in Experimental Mouse Models

    PubMed Central

    van Swelm, Rachel P. L.; Theurl, Milan; Theurl, Igor; Kemna, Erwin H.; van der Burgt, Yuri E. M.; Venselaar, Hanka; Dutilh, Bas E.; Russel, Frans G. M.; Weiss, Günter; Masereeuw, Rosalinde; Fleming, Robert E.; Swinkels, Dorine W.

    2011-01-01

    The mouse is a valuable model for unravelling the role of hepcidin in iron homeostasis, however, such studies still report hepcidin mRNA levels as a surrogate marker for bioactive hepcidin in its pivotal function to block ferroportin-mediated iron transport. Here, we aimed to assess bioactive mouse Hepcidin-1 (Hep-1) and its paralogue Hepcidin-2 (Hep-2) at the peptide level. To this purpose, fourier transform ion cyclotron resonance (FTICR) and tandem-MS was used for hepcidin identification, after which a time-of-flight (TOF) MS-based methodology was exploited to routinely determine Hep-1 and -2 levels in mouse serum and urine. This method was biologically validated by hepcidin assessment in: i) 3 mouse strains (C57Bl/6; DBA/2 and BABL/c) upon stimulation with intravenous iron and LPS, ii) homozygous Hfe knock out, homozygous transferrin receptor 2 (Y245X) mutated mice and double affected mice, and iii) mice treated with a sublethal hepatotoxic dose of paracetamol. The results showed that detection of Hep-1 was restricted to serum, whereas Hep-2 and its presumed isoforms were predominantly present in urine. Elevations in serum Hep-1 and urine Hep-2 upon intravenous iron or LPS were only moderate and varied considerably between mouse strains. Serum Hep-1 was decreased in all three hemochromatosis models, being lowest in the double affected mice. Serum Hep-1 levels correlated with liver hepcidin-1 gene expression, while acute liver damage by paracetamol depleted Hep-1 from serum. Furthermore, serum Hep-1 appeared to be an excellent indicator of splenic iron accumulation. In conclusion, Hep-1 and Hep-2 peptide responses in experimental mouse agree with the known biology of hepcidin mRNA regulators, and their measurement can now be implemented in experimental mouse models to provide novel insights in post-transcriptional regulation, hepcidin function, and kinetics. PMID:21408141

  18. Anti-granuloma activity of Coriandrum sativum in experimental models

    PubMed Central

    Nair, Vinod; Singh, Surender; Gupta, Yogendra Kumar

    2013-01-01

    Background: Coriandrum sativum has been used in the traditional systems of medicine for management of arthritis and other inflammatory disorders. Objectives: In this study, we have evaluated the anti-inflammatory and anti-granuloma activities of Coriandrum sativum hydroalcoholic extract (CSHE) in experimental models. Materials and Methods: The anti-inflammatory activity of CSHE was evaluated using carrageenan-induced paw edema model and the anti-granuloma activity of CSHE was evaluated using the subcutaneous cotton pellet implantation-induced granuloma formation and stimulation of peritoneal macrophages with complete Freund's adjuvant. Serum tumor necrosis factor-α (TNF-α), IL-6, IL-1 β levels, and peritoneal macrophage expression of TNF-R1 were evaluated as markers of global inflammation. Results: CSHE at the highest dose tested (32 mg/kg) produced a significant reduction (P < 0.05) in paw edema after carrageenan administration. CSHE treatment also reduced dry granuloma weight in all treated animals. Serum IL-6 and IL-1 β levels were significantly (P < 0.05) lower in the CSHE (32 mg/kg)-treated group as compared to control. Although there was an increase in serum TNF-α level in the CSHE-treated group as compared to control, TNF-R1 expression on peritoneal macrophages was found to be reduced. Conclusion: Thus, the result of this study demonstrates the anti-inflammatory and anti-granuloma activities of CSHE in experimental models, and validates its traditional use for the management of arthritis and other inflammatory disorders. PMID:23741156

  19. Role of breathing in cardiac performance: experimental and mathematical models

    NASA Astrophysics Data System (ADS)

    Tran, Binh Q.; Hoffman, Eric A.

    1999-05-01

    Due to the close proximity of the heart and lungs within a closed chest environment, we expect breathing to affect various cardiac performance parameters and hence cardiac output. We present an integrative approach to study heart-lung interactions, combining a mathematical formulation of the circulation system with imaging techniques using echo-planar magnetic resonance imaging (EPI) and dynamic x-ray CT (EBCT). We hypothesize that appropriate synchronization of mechanical ventilation to cardiac-cycle specific events can improve cardiac function, i.e. stroke volume (SV) and cardiac output (CO). Computational and experimental results support the notion that heart-lung interaction, leading to altered cardiac output associated with inspiration/expiration, is not directly associated with lung inflation/deflation and thus is felt to be more influenced by pleural pressure changes. The mathematical model of the circulation demonstrates the importance of cardiac-cycle specific timing of ventilation on cardiac function and matches with experimentally observed relationships found in animal models studied via EBCT and human studies using EPI. Results show that positive pressure mechanical ventilation timed to systolic events may increase SV and CO by up to 30%, mainly by increased filling of the ventricles during diastole. Similarly, negative pressure (spontaneous) respiration has its greatest effect on ventricular diastolic filling. Cardiac-gated mechanical ventilation may provide sufficient cardiac augmentation to warrant further investigation as a minimally-invasive technique for temporary cardiac assist. Through computational modeling and advanced imaging protocols, we were able to uniquely study heart-lung interactions within the intact milieu of the never-invaded thorax.

  20. Effects of tenoxicam in experimental corrosive esophagitis model.

    PubMed

    Erbaş, M; Kiraz, H A; Küçük, A; Topaloğlu, N; Erdem, H; Şahin, H; Toman, H; Ozkan, M Turgut Alper

    2015-04-01

    Esophageal stricture, one of the important complications of corrosive esophagus, develops following edema and granulation tissue that forms during and after the inflammatory reactions. Tenoxicam, a non-steroid anti-inflammatory drug with a long half-life, prevents various leukocyte functions including phagocyte and histamine secretion by inhibiting prostaglandin synthesis and removes various oxygen radicals in the region of inflammation. We designed this as a histopathological study using tenoxicam in rats for which we created a corrosive esophagus model. After necessary authorizations were obtained, the study was performed in Çanakkale 18 Mart University experimental animal laboratory. Twenty-four Wistar albino rats, weighing 220-240 g, were used for the experiment. Experimental animals were randomized into three groups: tenoxicam group (group T, n:8), control group (group C, n:8), and sham group (group S, n:8). Tenoxicam 0.5 mg/kg/day was administered to animals in group T, where esophageal burn was developed experimentally, 5 mg/kg 0.9% NaCL was administered i.p. to rats in group C for 15 days, once in 24 hours. No procedure was applied to rats in group S. After 15 days, all animals were sacrificed under general anesthesia and their esophagi were extracted. As a result of histopathological evaluation, inflammation and fibroblast proliferation was not observed in rats in the sham group (group S). Intense inflammation was observed in six rats (6+/2-) in the control group, and fibroblast proliferation was observed as 5+/3-. And in treatment groups, inflammation was evaluated as 3+/5-, and fibroblast proliferation as 3+/5-. In our study, histopathologic damage score was higher in the control group (P < 0.005). We deduce that tenoxicam can be useful in the treatment of caustic esophageal injuries in the acute phase, but think that these drugs require further researches and clinical studies before routine clinical use.

  1. Predicting subsurface uranium transport: Mechanistic modeling constrained by experimental data

    NASA Astrophysics Data System (ADS)

    Ottman, Michael; Schenkeveld, Walter D. C.; Kraemer, Stephan

    2017-04-01

    Depleted uranium (DU) munitions and their widespread use throughout conflict zones around the world pose a persistent health threat to the inhabitants of those areas long after the conclusion of active combat. However, little emphasis has been put on developing a comprehensive, quantitative tool for use in remediation and hazard avoidance planning in a wide range of environments. In this context, we report experimental data on U interaction with soils and sediments. Here, we strive to improve existing risk assessment modeling paradigms by incorporating a variety of experimental data into a mechanistic U transport model for subsurface environments. 20 different soils and sediments from a variety of environments were chosen to represent a range of geochemical parameters that are relevant to U transport. The parameters included pH, organic matter content, CaCO3, Fe content and speciation, and clay content. pH ranged from 3 to 10, organic matter content from 6 to 120 g kg-1, CaCO3 from 0 to 700 g kg-1, amorphous Fe content from 0.3 to 6 g kg-1 and clay content from 4 to 580 g kg-1. Sorption experiments were then performed, and linear isotherms were constructed. Sorption experiment results show that among separate sets of sediments and soils, there is an inverse correlation between both soil pH and CaCO¬3 concentration relative to U sorptive affinity. The geological materials with the highest and lowest sorptive affinities for U differed in CaCO3 and organic matter concentrations, as well as clay content and pH. In a further step, we are testing if transport behavior in saturated porous media can be predicted based on adsorption isotherms and generic geochemical parameters, and comparing these modeling predictions with the results from column experiments. The comparison of these two data sets will examine if U transport can be effectively predicted from reactive transport modeling that incorporates the generic geochemical parameters. This work will serve to show

  2. Comparisons Between Experimental Transport Analysis and Theoretical Modeling on LHD

    NASA Astrophysics Data System (ADS)

    Yamazaki, Kozo; LHD Group

    2000-10-01

    Helical plasma confinement system has a great advantage in producing steady-state high performance plasmas with built-in divertor. For the experimental analysis and predictive simulation of helical and tokamak plasmas, a simulation code TOTAL (TOroidal Transport Analysis Linkage) has been developed and is applied to the Large Helical Device (LHD, R=3.6 ~3.9m, B<3.0T ) experiments. In the LHD experiment, the global plasma confinement is ~1.5-2 times better than the well-known confinement scaling laws, and effective transport diffusivity is same order of magnitude of neoclassical ion transport with the assumption of Ti=Te. The radial electric field has been measured and roughly agrees with theoretical neoclassical values. The simple drift wave transport models are also compared with experimental values. The impurity dynamics are calculated using predictive part of the TOTAL code, and compared with the "breathing plasma" dynamics, and the role of high-Z impurity are clarified. For the analysis of high beta plasmas, local ballooning mode analysis will be added in this TOTAL code, and optimized configurations for the future MHR reactor will be searched.

  3. Human embryonic stem cell lines model experimental human cytomegalovirus latency.

    PubMed

    Penkert, Rhiannon R; Kalejta, Robert F

    2013-05-28

    Herpesviruses are highly successful pathogens that persist for the lifetime of their hosts primarily because of their ability to establish and maintain latent infections from which the virus is capable of productively reactivating. Human cytomegalovirus (HCMV), a betaherpesvirus, establishes latency in CD34(+) hematopoietic progenitor cells during natural infections in the body. Experimental infection of CD34(+) cells ex vivo has demonstrated that expression of the viral gene products that drive productive infection is silenced by an intrinsic immune defense mediated by Daxx and histone deacetylases through heterochromatinization of the viral genome during the establishment of latency. Additional mechanistic details about the establishment, let alone maintenance and reactivation, of HCMV latency remain scarce. This is partly due to the technical challenges of CD34(+) cell culture, most notably, the difficulty in preventing spontaneous differentiation that drives reactivation and renders them permissive for productive infection. Here we demonstrate that HCMV can establish, maintain, and reactivate in vitro from experimental latency in cultures of human embryonic stem cells (ESCs), for which spurious differentiation can be prevented or controlled. Furthermore, we show that known molecular aspects of HCMV latency are faithfully recapitulated in these cells. In total, we present ESCs as a novel, tractable model for studies of HCMV latency.

  4. [Experimental modeling of the blood vessels magnetic embolization].

    PubMed

    Iacob, Gh; Ciochină, Al D; Bredeţean, O

    2005-01-01

    The embolization of blood vessels is used on a large scale: the method is applied in different diseases, in the ablation of organs, but especially in tumor necrosis. The embolization can be also magnetic, if the embolus is obtained through the deposit in the vessel of magnetic nano or microparticles in the presence of an external magnetic field. The objective of our study was the modeling of the magnetic embolization using amorphous magnetic microspheres that have strong magnetic properties and are biocompatible. Experimental tests were made in order to observe the building of the magnetic embolus inside a thin spiral tube and to determine the influence of some parameters on the efficiency of occlusions: the dimensions of magnetic microspheres (1-300 mm), the debit of the liquid (4.66 - 16.5 ml/min), the viscosity of the carrier liquid (1.007 - 7.34 cSt), the direction and the intensity of the external magnetic field (340 - 600 Gs), the shape of the tube and the linear length of the deposit (5 - 50 mm). Under pre-established experimental conditions the efficiencies of occlusions were between 67% and 100%.

  5. Modeling and experimental data of zirconium-89 production yield.

    PubMed

    Sharifian, Mozhgan; Sadeghi, Mahdi; Alirezapour, Behrouz; Yarmohammadi, Mohammad; Ardaneh, Khosro

    2017-09-29

    The radionuclide zirconium-89 can be employed for the positron emission tomography (PET). In this study (89)Zr excitation function via (89)Y(p,n)(89)Zr reaction was calculated by the TALYS-1.8 code based on microscopic level density model. The formation of (89)Zr was simulated using the Monte Carlo simulation code MCNPX to calculate the integral yield in the (89)Y target body for threshold up to 40MeV incident-proton energy. The target thickness was based on calculation of the stopping power using the SRIM-2013 code matched to any incident-proton energy. The production yield of the (89)Zr simulated with the Monte Carlo method for the (89)Y(p,n)(89)Zr, (89)Y(d,2n)(89)Zr, (nat)Sr(α,xn)(89)Zr and (nat)Zr(p,pxn)(89)Zr reactions and the results were in good agreement with published experimental results for the optimum energy range. An experimental yield of 53.1MB/µA for the 15MeV proton-induced on Y2O3 powder as a disk-target obtained for 1h irradiation at the AMIRS cyclotron. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Evaluation of two experimental models of hepatic encephalopathy in rats.

    PubMed

    García-Moreno, L M; Conejo, N M; González-Pardo, H; Aller, M A; Nava, M P; Arias, J; Arias, J L

    2005-01-01

    The serious neuropsychological repercussions of hepatic encephalopathy have led to the creation of several experimental models in order to better understand the pathogenesis of the disease. In the present investigation, two possible causes of hepatic encephalopathy, cholestasis and portal hypertension, were chosen to study the behavioral impairments caused by the disease using an object recognition task. This working memory test is based on a paradigm of spontaneous delayed non-matching to sample and was performed 60 days after surgery. Male Wistar rats (225-250 g) were divided into three groups: two experimental groups, microsurgical cholestasis (N = 20) and extrahepatic portal hypertension (N = 20), and a control group (N = 20). A mild alteration of the recognition memory occurred in rats with cholestasis compared to control rats and portal hypertensive rats. The latter group showed the poorest performance on the basis of the behavioral indexes tested. In particular, only the control group spent significantly more time exploring novel objects compared to familiar ones (P < 0.001). In addition, the portal hypertension group spent the shortest time exploring both the novel and familiar objects (P < 0.001). These results suggest that the existence of portosystemic collateral circulation per se may be responsible for subclinical encephalopathy.

  7. Thermal infrared spectroscopy and modeling of experimentally shocked basalts

    USGS Publications Warehouse

    Johnson, J. R.; Staid, M.I.; Kraft, M.D.

    2007-01-01

    New measurements of thermal infrared emission spectra (250-1400 cm-1; ???7-40 ??m) of experimentally shocked basalt and basaltic andesite (17-56 GPa) exhibit changes in spectral features with increasing pressure consistent with changes in the structure of plagioclase feldspars. Major spectral absorptions in unshocked rocks between 350-700 cm-1 (due to Si-O-Si octahedral bending vibrations) and between 1000-1250 cm-1 (due to Si-O antisymmetric stretch motions of the silica tetrahedra) transform at pressures >20-25 GPa to two broad spectral features centered near 950-1050 and 400-450 cm-1. Linear deconvolution models using spectral libraries composed of common mineral and glass spectra replicate the spectra of shocked basalt relatively well up to shock pressures of 20-25 GPa, above which model errors increase substantially, coincident with the onset of diaplectic glass formation in plagioclase. Inclusion of shocked feldspar spectra in the libraries improves fits for more highly shocked basalt. However, deconvolution models of the basaltic andesite select shocked feldspar end-members even for unshocked samples, likely caused by the higher primary glass content in the basaltic andesite sample.

  8. Computational and experimental modeling of runaway electron damage

    SciTech Connect

    Niemer, K.A.; Gilligan, J.G. . Dept. of Nuclear Engineering); Croessmann, C.D. ); Bolt, H.H. . NET Design Team)

    1990-06-01

    Cracking, craters, spotty damage (discoloration), and missing chunks of material have been observed on limiters and along the midplane of tokamak inner walls. This damage is assumed to be due to runaway electron discharges. These runaway electrons have been predicted to range in energy from a few MeV to several hundred MeV. The energy density from the runaway electron discharges ranges from 10 to 500 MJ/m{sup 2} over pulse lengths of 5 to 50 msec. The PTA code package is a unique application of PATRAN, the Integrated TIGER Series, and ABAQUS for modeling high energy electron impact on tokamak first wall and limiter materials. The PTA code package provides a three-dimensional, time dependent, computational code package which predicts energy deposition, temperature rise, and damage on relevant fusion materials from runaway electrons. In this benchmark study, three experiments were modeled to validate the PTA code package. The first and third experiment simulated runaway electrons scattering through a plasma facing surface (graphite) into an internal structure (copper), and the second experiment tested the thermal and structural response from high energy electron impact on different fusion relevant materials. The PTA calculations compared favorably with the experimental results. In particular, the PTA models identified gap conductance, thermal contact, x-ray generation in materials, and the placement of high stopping power materials as key factors in the design of plasma facing components that are resistant to runaway electron damage. 13 refs., 40 figs., 3 tabs.

  9. Interventional neuroradiology: the role of experimental models in scientific progress.

    PubMed

    Raymond, J; Salazkin, I; Gevry, G; Nguyen, T N

    2007-03-01

    The ultimate methodology necessary to adopt a treatment as generally beneficial is the randomized controlled trial, a method designed by and for clinicians to maximize the care of their patients in the presence of uncertainty. Some selection is however necessary to limit trials to more promising and less risky endeavors. Experimental models are the privileged answer to the problem of finding scientific evidence while refraining from harming patients in the course of this pursuit. They allow a step by step assessment, from simple but artificial settings to more complex and realistic animal models. But the use of animal models can only be justified if the community can be convinced that alternatives have been considered but are invalid, when the project is scientifically sound and methodologically irreproachable. As neurointerventional methods develop and gain wider clinical applications, progress should proceed in an orderly fashion, within limits set by prudence and human values, from the less risky, costly, time consuming methods, to the more definite, pragmatic, labor intensive but inescapable clinical trials. Each step is essential and the sequence cannot be violated without risks of errors that eventually translate into clinical morbidity.

  10. Computational reverse shoulder prosthesis model: Experimental data and verification.

    PubMed

    Martins, A; Quental, C; Folgado, J; Ambrósio, J; Monteiro, J; Sarmento, M

    2015-09-18

    The reverse shoulder prosthesis aims to restore the stability and function of pathological shoulders, but the biomechanical aspects of the geometrical changes induced by the implant are yet to be fully understood. Considering a large-scale musculoskeletal model of the upper limb, the aim of this study is to evaluate how the Delta reverse shoulder prosthesis influences the biomechanical behavior of the shoulder joint. In this study, the kinematic data of an unloaded abduction in the frontal plane and an unloaded forward flexion in the sagittal plane were experimentally acquired through video-imaging for a control group, composed of 10 healthy shoulders, and a reverse shoulder group, composed of 3 reverse shoulders. Synchronously, the EMG data of 7 superficial muscles were also collected. The muscle force sharing problem was solved through the minimization of the metabolic energy consumption. The evaluation of the shoulder kinematics shows an increase in the lateral rotation of the scapula in the reverse shoulder group, and an increase in the contribution of the scapulothoracic joint to the shoulder joint. Regarding the muscle force sharing problem, the musculoskeletal model estimates an increased activity of the deltoid, teres minor, clavicular fibers of the pectoralis major, and coracobrachialis muscles in the reverse shoulder group. The comparison between the muscle forces predicted and the EMG data acquired revealed a good correlation, which provides further confidence in the model. Overall, the shoulder joint reaction force was lower in the reverse shoulder group than in the control group. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Experimental modeling of jet-ring turbine disk cooling

    NASA Technical Reports Server (NTRS)

    Metzger, D. E.; Kim, Y. W.

    1991-01-01

    The experimental facility and some early results are described from a current research program modeling turbine disk cooling with multiple impinging jets, such as employed on the Space Shuttle Main Engine oxygen turbopump. The study is designed to obtain detailed local convection heat transfer rates on specially constructed turbine disk models that employ either multiple cooling jet impingement near the disk outer radius from a jet ring, or alternatively, single entrance coolant supply into the center of the disk cavity. Jet impingement is an effective scheme for cooling of turbine disks at or near the blade attachment region, but the heat transfer mechanisms and merits relative to other schemes are not well understood. The present study employs two specially constructed full scale plastic model disks, contoured and plane, together with the corresponding stators. Local heat transfer rates are determined by a computer vision system from the response of thin liquid crystal coatings applied to the disk test faces. The present results indicate that multiple jet impingement directed at the blade attachment region results in higher cooling rates in that region than does the same flow supplied to the disk center, but this conclusion must be regarded as tentative.

  12. Experimental models of inherited cardiomyopathy and its therapeutics

    PubMed Central

    Nonaka, Miki; Morimoto, Sachio

    2014-01-01

    Cardiomyopathy is a disease of myocardium categorized into three major forms, hypertrophic (HCM), dilated (DCM) and restrictive cardiomyopathy (RCM), which has recently been demonstrated to be a monogenic disease due to mutations in various proteins expressed in cardiomyocytes. Mutations in HCM and RCM typically increase the myofilament sensitivity to cytoplasmic Ca2+, leading to systolic hyperfunction and diastolic dysfunction. In contrast, mutations in DCM typically decrease the myofilament sensitivity to cytoplasmic Ca2+ and/or force generation/transmission, leading to systolic dysfunction. Creation of genetically-manipulated transgenic and knock-in animals expressing mutant proteins exogenously and endogenously, respectively, in their hearts provides valuable animal models to discover the molecular and cellular mechanisms for pathogenesis and promising therapeutic strategy in vivo. Recently, cardiomyocytes have been differentiated from patient’s induced pluripotent stem cells as a model of inherited cardiomyopathies in vitro. In this review, we provide overview of experimental models of cardiomyopathies with a focus on revealed molecular and cellular pathogenic mechanisms and potential therapeutics. PMID:25548614

  13. Experimental models of perinatal hypoxic-ischemic brain damage.

    PubMed

    Vannucci, R C

    1993-01-01

    Animal research has provided important information on the pathogenesis of and neuropathologic responses to perinatal cerebral hypoxia-ischemia. In experimental animals, structural brain damage from hypoxia-ischemia has been produced in immature rats, rabbits, guinea pigs, sheep and monkeys (18, 20, 24, 25, 38). Of the several available animal models, the fetal and newborn rhesus monkey and immature rat have been studied most extensively because of their similarities to humans in respect to the physiology of reproduction and their neuroanatomy at or shortly following birth. Given the frequency of occurrence of human perinatal hypoxic-ischemic brain damage and the multiple, often severe neurologic handicaps which ensue in infants and children, it is not surprising that the above described animal models have been developed. These models have provided the basis for investigations to clarify not only physiologic and biochemical mechanisms of tissue injury but also the efficacy of specific management strategies. Hopefully, such animal research will continue to provide important information regarding how best to prevent or minimize the devastating consequences of perinatal cerebral hypoxia-ischemia.

  14. Experimental autoimmune orchitis as a model of immunological male infertility.

    PubMed

    Naito, Munekazu; Terayama, Hayato; Hirai, Shuichi; Qu, Ning; Lustig, Livia; Itoh, Masahiro

    2012-12-01

    Clinically, 60-75% of male infertility cases are categorized as idiopathic spermatogenic disturbance. In previous studies of this condition, lymphocytic infiltration and immune deposits were present in several testis biopsy specimens, indicating that inflammatory or immunological factors contribute to the occurrence of the lesions. However, there is currently little evidence regarding immunological infertility in men. Previously, we established an immunological infertility model, experimental autoimmune orchitis (EAO), that can be induced in mice by two subcutaneous injections of viable syngeneic testicular germ cells without the use of any adjuvant. In this EAO model, lymphocytes surround the tubuli recti and then induce spermatogenic disturbance. In addition, after the active inflammation stage of this model, the seminiferous epithelium is damaged irreversibly, resembling the histopathology of human male idiopathic spermatogenic disturbance. In the majority of patients with testicular autoimmunity, there is a chronic and asymptomatic development of the inflammatory reaction. Therefore, this disease is very difficult to diagnose at the ongoing stage, and it is possible that the histopathology of idiopathic spermatogenic disturbance in the clinic is reported at the post-active inflammation stage of autoimmune orchitis. In this review, the histopathology of EAO before and after inflammation is discussed, comparing it with human orchitis.

  15. An ameliorated skin flap model in rats for experimental research.

    PubMed

    Hosnuter, Mübin; Kargi, Eksal; Peksoy, Irfan; Babucçu, Orhan; Payasli, Cem

    2006-01-01

    There is a disagreement in the experimental design of random skin flaps owing to their vascular inconsistency. The definition of a reliable axial-pattern skin flap model is needed. The purpose of this study was to describe a new skin flap model to deal with entire drawbacks of existing random and axial pattern skin flap designs. This was accomplished by creating paired skin flaps including both skin and vascular pedicle on the dorsum of the same rat. This design was suitably termed as rando-axial flap. The present study offers a simple and reliable skin flap model with following advantages: (1) it has a predictable necrosis area, (2) it reveals a larger survival area (75 +/- 5%) when compared to other flaps in this study (Mann-Whitney U-test, p<0.001), (3) the vascular pedicle is consistent, (4) control and study flaps are placed on the same animal (5) it can be converted to a random, an axial or a free flap.

  16. Magnetic dynamics of ferrofluids: mathematical models and experimental investigations

    NASA Astrophysics Data System (ADS)

    Wu, Kai; Tu, Liang; Su, Diqing; Wang, Jian-Ping

    2017-03-01

    Magnetite ferrofluids with unique magnetic behaviors are attractive for biomedical applications such as magnetic fluid hyperthermia and magnetic particle imaging. A precise nanoparticle-specific characterization by theoretical models and experiments to predict dynamics of ferrofluids and optimize their behaviors for emerging biomedical applications is necessary. In this paper, combining experiments and modeling, we have uncovered interesting magnetic dynamics of nanoparticles that are dependent on magnetic field strength, polymer coating of nanoparticles, viscosity of ferrofluid, and dipolar interactions. It is concluded that either by changing the magnitude of magnetic field or the concentrations of nanoparticles, we are able to convert the dominating relaxation process of magnetic nanoparticles from Néel to Brownian, and vice versa. Polymer coatings on nanoparticles and viscosity of ferrofluids are demonstrated to have varying degrees of influence on effective relaxation times of nanoparticles with different sizes and under different field strengths. Our theoretical models are used to predict the magnetic response of ferrofluid consisting of 35 nm magnetite nanoparticles under alternating magnetic fields, and it turns out that our theoretical data fits well with the experimental data.

  17. Experimental validation of a numerical model for subway induced vibrations

    NASA Astrophysics Data System (ADS)

    Gupta, S.; Degrande, G.; Lombaert, G.

    2009-04-01

    This paper presents the experimental validation of a coupled periodic finite element-boundary element model for the prediction of subway induced vibrations. The model fully accounts for the dynamic interaction between the train, the track, the tunnel and the soil. The periodicity or invariance of the tunnel and the soil in the longitudinal direction is exploited using the Floquet transformation, which allows for an efficient formulation in the frequency-wavenumber domain. A general analytical formulation is used to compute the response of three-dimensional invariant or periodic media that are excited by moving loads. The numerical model is validated by means of several experiments that have been performed at a site in Regent's Park on the Bakerloo line of London Underground. Vibration measurements have been performed on the axle boxes of the train, on the rail, the tunnel invert and the tunnel wall, and in the free field, both at the surface and at a depth of 15 m. Prior to these vibration measurements, the dynamic soil characteristics and the track characteristics have been determined. The Bakerloo line tunnel of London Underground has been modelled using the coupled periodic finite element-boundary element approach and free field vibrations due to the passage of a train at different speeds have been predicted and compared to the measurements. The correspondence between the predicted and measured response in the tunnel is reasonably good, although some differences are observed in the free field. The discrepancies are explained on the basis of various uncertainties involved in the problem. The variation in the response with train speed is similar for the measurements as well as the predictions. This study demonstrates the applicability of the coupled periodic finite element-boundary element model to make realistic predictions of the vibrations from underground railways.

  18. BUILD: a program generator for modelling experimental biological data.

    PubMed

    Rodriguez, F; Altibelli, A; Lopez, A

    1994-04-01

    BUILD is a program generator acting at source code level. The generated code corresponds to a whole application in order to model a biological process of interest using an iterative adjustment of experimental data. The program is designed to be executed in command line mode for processing of multiple data files with an individual execution control for each file. The results are completed by modular statistical and graphical functions. This approach has been shown to reduce the time and the amount of work needed for program development, debugging and maintenance. To date, BUILD has been successfully used in mathematical analysis of phenomenological approaches, but other fields of activity, such as educational software, are also conceivable.

  19. Experimental verification of theoretical model for speckle intensity excursion areas

    SciTech Connect

    Alexander, T.L.; Harvey, J.E.; Hefele, D.

    1994-12-31

    Speckle is inherently an interference phenomenon produced when a rough object or turbulent medium introduces some degree of randomness to a reflected or transmitted electromagnetic field. Speckle characteristics are therefore a major concern in many laser imaging or wave propagation applications. For many applications, a detailed description of speckle size as a function of intensity threshold level is desirable. Extensive experimental measurements of average speckle size as a function of intensity threshold level were therefore made for several different targets and illumination conditions. The authors then compare these measurements with a theoretical model for excursion areas of speckle intensity. Excellent agreement is obtained for intensity threshold levels greater than approximately twice the mean intensity level.

  20. Practical application of stereological methods in experimental kidney animal models.

    PubMed

    Fernández García, María Teresa; Núñez Martínez, Paula; García de la Fuente, Vanessa; Sánchez Pitiot, Marta; Muñiz Salgueiro, María Del Carmen; Perillán Méndez, Carmen; Argüelles Luis, Juan; Astudillo González, Aurora

    The kidneys are vital organs responsible for excretion, fluid and electrolyte balance and hormone production. The nephrons are the kidney's functional and structural units. The number, size and distribution of the nephron components contain relevant information on renal function. Stereology is a branch of morphometry that applies mathematical principles to obtain three-dimensional information from serial, parallel and equidistant two-dimensional microscopic sections. Because of the complexity of stereological studies and the lack of scientific literature on the subject, the aim of this paper is to clearly explain, through animal models, the basic concepts of stereology and how to calculate the main kidney stereological parameters that can be applied in future experimental studies. Copyright © 2016 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.

  1. Tupaia Belangeri as an Experimental Animal Model for Viral Infection

    PubMed Central

    Tsukiyama-Kohara, Kyoko; Kohara, Michinori

    2014-01-01

    Tupaias, or tree shrews, are small mammals that are similar in appearance to squirrels. The morphological and behavioral characteristics of the group have been extensively characterized, and despite previously being classified as primates, recent studies have placed the group in its own family, the Tupaiidae. Genomic analysis has revealed that the genus Tupaia is closer to humans than it is to rodents. In addition, tupaias are susceptible to hepatitis B virus and hepatitis C virus. The only other experimental animal that has been demonstrated to be sensitive to both of these viruses is the chimpanzee, but restrictions on animal testing have meant that experiments using chimpanzees have become almost impossible. Consequently, the development of the tupaia for use as an animal infection model could become a powerful tool for hepatitis virus research and in preclinical studies on drug development. PMID:25048261

  2. Some advances in experimentation supporting development of viscoplastic constitutive models

    NASA Technical Reports Server (NTRS)

    Ellis, J. R.; Robinson, D. N.

    1985-01-01

    The development of a biaxial extensometer capable of measuring axial, torsion, and diametral strains to near-microstrain resolution at elevated temperatures is discussed. An instrument with this capability was needed to provide experimental support to the development of viscoplastic constitutive models. The advantages gained when torsional loading is used to investigate inelastic material response at elevated temperatures are highlighted. The development of the biaxial extensometer was conducted in two stages. The first involved a series of bench calibration experiments performed at room temperature. The second stage involved a series of in-place calibration experiments performed at room temperature. A review of the calibration data indicated that all performance requirements regarding resolution, range, stability, and crosstalk had been met by the subject instrument over the temperature range of interest, 21 C to 651 C. The scope of the in-placed calibration experiments was expanded to investigate the feasibility of generating stress relaxation data under torsional loading.

  3. Some advances in experimentation supporting development of viscoplastic constitutive models

    NASA Technical Reports Server (NTRS)

    Ellis, J. R.; Robinson, D. N.

    1985-01-01

    The development of a biaxial extensometer capable of measuring axial, torsion, and diametral strains to near-microstrain resolution at elevated temperatures is discussed. An instrument with this capability was needed to provide experimental support to the development of viscoplastic constitutive models. The advantages gained when torsional loading is used to investigate inelastic material response at elevated temperatures are highlighted. The development of the biaxial extensometer was conducted in two stages. The first involved a series of bench calibration experiments performed at room temperature. The second stage involved a series of in-place calibration experiments conducted at room and elevated temperature. A review of the calibration data indicated that all performance requirements regarding resolution, range, stability, and crosstalk had been met by the subject instrument over the temperature range of interest, 21 C to 651 C. The scope of the in-place calibration experiments was expanded to investigate the feasibility of generating stress relaxation data under torsional loading.

  4. Cracking in autoclaved aerated concrete: Experimental investigation and XFEM modeling

    SciTech Connect

    Ferretti, D.

    2015-01-15

    The paper aims to investigate and model cracking development in beams and deep-beams made of autoclaved aerated concrete (AAC). Fracture mechanics of AAC has been first studied by performing three-point bending tests on beams, similar to those commonly used for ordinary concrete elements. In some of these tests, crack growth has been also monitored by using ESPI laser technique. In this way, it has been possible to calibrate the main parameters of a proper cohesive law by means of extended finite element inverse analysis. Subsequently, cracking tests have been also performed on deep-beams, whose behavior is more representative of full scale walls. To validate the proposed cohesive law, deep-beam experimental behavior has been finally simulated through XFEM.

  5. Inhibitors of sex hormones: development of experimental models.

    PubMed

    Frost, P; Gomez, E C

    1972-01-01

    Inhibitors of sex hormones and the development of experimental models are discussed. Compounds that inhibit the action of androgens and estrogens are defined, and the possible mechanisms of action presented are: 1) inhibition of hormone synthesis; 2) inhibition of uptake of hormone into target tissues; 3) inhibition of the retention of hormone in target tissues; 4) inhibition of the binding of hormone to nonenzyme macromolecules; and 5) inhibition of the metabolism of a hormone to a more active form. Effects of antiandrogen on skin such as hirsutism, sebum production, and acne are briefly covered. Methods of study included inhibition of in vitro metabolism of testosterone by human foreskin and the use of the hamster flank organ for the bioassay of antiandrogens.

  6. Tupaia belangeri as an experimental animal model for viral infection.

    PubMed

    Tsukiyama-Kohara, Kyoko; Kohara, Michinori

    2014-01-01

    Tupaias, or tree shrews, are small mammals that are similar in appearance to squirrels. The morphological and behavioral characteristics of the group have been extensively characterized, and despite previously being classified as primates, recent studies have placed the group in its own family, the Tupaiidae. Genomic analysis has revealed that the genus Tupaia is closer to humans than it is to rodents. In addition, tupaias are susceptible to hepatitis B virus and hepatitis C virus. The only other experimental animal that has been demonstrated to be sensitive to both of these viruses is the chimpanzee, but restrictions on animal testing have meant that experiments using chimpanzees have become almost impossible. Consequently, the development of the tupaia for use as an animal infection model could become a powerful tool for hepatitis virus research and in preclinical studies on drug development.

  7. Laser melting of carbide tool surface: Model and experimental studies

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Shuja, S. Z.; Khan, S. M. A.; Aleem, A.

    2009-09-01

    Laser controlled melting is one of the methods to achieve structural integrity in the surface region of the carbide tools. In the present study, laser heating of carbide cutting tool and temperature distribution in the irradiated region are examined. The phase change process during the heating is modeled using the enthalpy-porosity method. The influence of laser pulse intensity distribution across the irradiated surface ( β) on temperature distribution and melt formation is investigated. An experiment is carried out and the microstructural changes due to laser consecutive pulse heating is examined using the scanning electron microscope (SEM). It is found that melt depth predicted agrees with the experimental results. The maximum depth of the melt layer moves away from the symmetry axis with increasing β.

  8. Experimental model of arthritis induced by Paracoccidioides brasiliensis in rats.

    PubMed

    Loth, Eduardo Alexandre; Biazin, Samia Khalil; Paula, Claudete Rodrigues; Simão, Rita de Cássia Garcia; de Franco, Marcello Fabiano; Puccia, Rosana; Gandra, Rinaldo Ferreira

    2012-09-01

    Paracoccidioidomycosis (PCM), a disease caused by the fungus Paracoccidioides brasiliensis (Pb), is highly prevalent in Brazil, where it is the principal cause of death by systemic mycoses. The disease primarily affects men aged 30-50 year old and usually starts as a pulmonary focus and then may spread to other organs and systems, including the joints. The present study aimed to develop an experimental model of paracoccidioidomycotic arthritis. Two-month-old male Wistar rats (n = 48) were used, divided in 6 groups: test groups EG/15 and EG/45 (received one dose of 100 μl of saline containing 10(5) Pb viable yeasts in the knee); heat killed Pb-group HK/15 and HK/45 (received a suspension of 10(5) Pb nonviable yeasts in the knee) and control groups CG/15 and CG/45 (received only sterile saline in the knee). The rats were killed 15 and 45 days postinoculation. In contrast with the control rats, the histopathology of the joints of rats of the test groups (EG/15 and EG/45) revealed a picture of well-established PCM arthritis characterized by extensive sclerosing granulomatous inflammation with numerous multiple budding fungal cells. The X-ray examination revealed joint alterations in these groups. Only metabolic active fungi evoked inflammation. The experimental model was able to induce fungal arthritis in the knees of the rats infected with metabolic active P. brasiliensis. The disease tended to be regressive and restrained by the immune system. No evidence of fungal dissemination to the lungs was observed.

  9. Bayesian experimental design for identification of model propositions and conceptual model uncertainty reduction

    NASA Astrophysics Data System (ADS)

    Pham, Hai V.; Tsai, Frank T.-C.

    2015-09-01

    The lack of hydrogeological data and knowledge often results in different propositions (or alternatives) to represent uncertain model components and creates many candidate groundwater models using the same data. Uncertainty of groundwater head prediction may become unnecessarily high. This study introduces an experimental design to identify propositions in each uncertain model component and decrease the prediction uncertainty by reducing conceptual model uncertainty. A discrimination criterion is developed based on posterior model probability that directly uses data to evaluate model importance. Bayesian model averaging (BMA) is used to predict future observation data. The experimental design aims to find the optimal number and location of future observations and the number of sampling rounds such that the desired discrimination criterion is met. Hierarchical Bayesian model averaging (HBMA) is adopted to assess if highly probable propositions can be identified and the conceptual model uncertainty can be reduced by the experimental design. The experimental design is implemented to a groundwater study in the Baton Rouge area, Louisiana. We design a new groundwater head observation network based on existing USGS observation wells. The sources of uncertainty that create multiple groundwater models are geological architecture, boundary condition, and fault permeability architecture. All possible design solutions are enumerated using a multi-core supercomputer. Several design solutions are found to achieve an 80%-identifiable groundwater model in 5 years by using six or more existing USGS wells. The HBMA result shows that each highly probable proposition can be identified for each uncertain model component once the discrimination criterion is achieved. The variances of groundwater head predictions are significantly decreased by reducing posterior model probabilities of unimportant propositions.

  10. Experimental and modelling evidence of shortening heat in cardiac muscle.

    PubMed

    Tran, Kenneth; Han, June-Chiew; Crampin, Edmund John; Taberner, Andrew James; Loiselle, Denis Scott

    2017-10-01

    Heat associated with muscle shortening has been repeatedly demonstrated in skeletal muscle, but its existence in cardiac muscle remains contentious after five decades of study. By iterating between experiments and computational modelling, we show compelling evidence for the existence of shortening heat in cardiac muscle and reveal, mechanistically, the source of this excess heat. Our results clarify a long-standing uncertainty in the field of cardiac muscle energetics. We provide a revised partitioning of cardiac muscle energy expenditure to include this newly revealed thermal component. When a muscle shortens against an afterload, the heat that it liberates is greater than that produced by the same muscle contracting isometrically at the same level of force. This excess heat is defined as 'shortening heat', and has been repeatedly demonstrated in skeletal muscle but not in cardiac muscle. Given the micro-structural similarities between these two muscle types, and since we imagine that shortening heat is the thermal accompaniment of cross-bridge cycling, we have re-examined this issue. Using our flow-through microcalorimeter, we measured force and heat generated by isolated rat trabeculae undergoing isometric contractions at different muscle lengths and work-loop (shortening) contractions at different afterloads. We simulated these experimental protocols using a thermodynamically constrained model of cross-bridge cycling and probed the mechanisms underpinning shortening heat. Predictions generated by the model were subsequently validated by a further set of experiments. Both our experimental and modelling results show convincing evidence for the existence of shortening heat in cardiac muscle. Its magnitude is inversely related to the afterload or, equivalently, directly related to the extent of shortening. Computational simulations reveal that the heat of shortening arises from the cycling of cross-bridges, and that the rate of ATP hydrolysis is more sensitive to

  11. Microbial dormancy improves development and experimental validation of ecosystem model.

    PubMed

    Wang, Gangsheng; Jagadamma, Sindhu; Mayes, Melanie A; Schadt, Christopher W; Steinweg, J Megan; Gu, Lianhong; Post, Wilfred M

    2015-01-01

    Climate feedbacks from soils can result from environmental change followed by response of plant and microbial communities, and/or associated changes in nutrient cycling. Explicit consideration of microbial life-history traits and functions may be necessary to predict climate feedbacks owing to changes in the physiology and community composition of microbes and their associated effect on carbon cycling. Here we developed the microbial enzyme-mediated decomposition (MEND) model by incorporating microbial dormancy and the ability to track multiple isotopes of carbon. We tested two versions of MEND, that is, MEND with dormancy (MEND) and MEND without dormancy (MEND_wod), against long-term (270 days) carbon decomposition data from laboratory incubations of four soils with isotopically labeled substrates. MEND_wod adequately fitted multiple observations (total C-CO2 and (14)C-CO2 respiration, and dissolved organic carbon), but at the cost of significantly underestimating the total microbial biomass. MEND improved estimates of microbial biomass by 20-71% over MEND_wod. We also quantified uncertainties in parameters and model simulations using the Critical Objective Function Index method, which is based on a global stochastic optimization algorithm, as well as model complexity and observational data availability. Together our model extrapolations of the incubation study show that long-term soil incubations with experimental data for multiple carbon pools are conducive to estimate both decomposition and microbial parameters. These efforts should provide essential support to future field- and global-scale simulations, and enable more confident predictions of feedbacks between environmental change and carbon cycling.

  12. Aspirin Intolerance: Experimental Models for Bed-to-Bench

    PubMed Central

    Yamashita, Masamichi

    2016-01-01

    Aspirin is the oldest non-steroidal anti-inflammatory drug (NSAID), and it sometimes causes asthma-like symptoms known as aspirin-exacerbated respiratory disease (AERD), which can be serious. Unwanted effects of aspirin (aspirin intolerance) are also observed in patients with food-dependent exercise-induced anaphylaxis, a type I allergy disease, and aspirin-induced urticaria (AIU). However the target and the mechanism of the aspirin intolerance are still unknown. There is no animal or cellular model of AERD, because its pathophysiological mechanism is still unknown, but it is thought that inhibition of cyclooxygenase by causative agents leads to an increase of free arachidonic acid, which is metabolized into cysteinyl leukotrienes (cysLTs) that provoke airway smooth muscle constriction and asthma symptoms. As the bed-to-bench approach, to confirm the clinical discussion in experimental cellular models, we have tried to develop a cellular model of AERD using activated RBL-2H3 cells, a rat mast cell like cell line. Indomethacin (another NSAID and also causes AERD), enhances in vitro cysLTs production by RBL-2H3 cells, while there is no induction of cysLTs production in the absence of inflammatory activation. Since this suggests that all inflammatory cells with activation of prostaglandin and cysLT metabolism should respond to NSAIDs, and then I have concluded that aspirin intolerance should be separated from subsequent bronchoconstriction. Evidence about the cellular mechanisms of NSAIDs may be employed for development of in vitro AERD models as the approach from bench-to-bed. PMID:27719658

  13. Experimental Characterization and Micromechanical Modelling of Anisotropic Slates

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Feng; Wei, Kai; Liu, Wu; Hu, Shao-Hua; Hu, Ran; Zhou, Chuang-Bing

    2016-09-01

    Laboratory tests were performed in this study to examine the anisotropic physical and mechanical properties of the well-foliated Jiujiang slate. The P-wave velocity and the apparent Young's modulus were found to increase remarkably with the foliation angle θ, and the compressive strength at any confining pressure varies in a typical U-shaped trend, with the maximum strength consistently attained at θ = 90° and the minimum strength at θ = 45°. The slate samples failed in three typical patterns relevant to the foliation angle, i.e. shear failure across foliation planes for θ ≤ 15°, sliding along foliation planes for 30° ≤ θ ≤ 60° and axial splitting along foliation planes for θ = 90°. The stress-strain curves at any given foliation angle and confining pressure display an initial nonlinear phase, a linear elastic phase, a crack initiation and growth phase, as well as a rapid stress drop phase and a residual stress phase. Based on the experimental evidences, a micromechanical damage-friction model was proposed for the foliated slate by simply modelling the foliation planes as a family of elastic interfaces and by characterizing the interaction between the foliation planes and the rock matrix with a nonlinear damage evolution law associated with the inclination angle. The proposed model was applied to predict the deformational and strength behaviours of the foliated slate under triaxial compressive conditions using the material parameters calibrated with the uniaxial and/or triaxial test data, with good agreement between the model predictions and the laboratory measurements.

  14. Polarisers in the focal domain: Theoretical model and experimental validation

    NASA Astrophysics Data System (ADS)

    Martínez-Herrero, Rosario; Maluenda, David; Juvells, Ignasi; Carnicer, Artur

    2017-02-01

    Polarisers are one of the most widely used devices in optical set-ups. They are commonly used with paraxial beams that propagate in the normal direction of the polariser plane. Nevertheless, the conventional projection character of these devices may change when the beam impinges a polariser with a certain angle of incidence. This effect is more noticeable if polarisers are used in optical systems with a high numerical aperture, because multiple angles of incidence have to be taken into account. Moreover, the non-transverse character of highly focused beams makes the problem more complex and strictly speaking, the Malus’ law does not apply. In this paper we develop a theoretical framework to explain how ideal polarisers affect the behavior of highly focused fields. In this model, the polarisers are considered as birefringent plates, and the vector behaviour of focused fields is described using the plane-wave angular spectrum approach. Experiments involving focused fields were conducted to verify the theoretical model and a satisfactory agreement between theoretical and experimental results was found.

  15. Oxidized LDL accumulation in experimental renal ischemia reperfusion injury model.

    PubMed

    Kulah, Eyup; Tascilar, Oge; Acikgoz, Serefden; Tekin, Ishak Ozel; Karadeniz, Guldeniz; Can, Murat; Gun, Banu; Barut, Figen; Comert, Mustafa

    2007-01-01

    The aim of this study was to identify oxidative damage of kidney during ischemia reperfusion injury (IRI) by evaluating changes in lipid peroxidation markers in tissue and blood by an experimental model. Oxidized LDL (ox-LDL) was used as an oxidative stress biomarker, whereas paraoxonase (PON-1) activity was used as an antioxidative biomarker. Sixty-three male Wistar rats were randomly assigned into three groups: renal IRI, sham, and control. In the renal IRI group, the right kidney was removed and the artery and vein of the left kidney were clamped for 90 minutes. The presence of ox-LDL in the kidney tissue sections was determined by using an immunofluorescent staining method. The plasma ox-LDL levels did not increase significantly at the 24th hour following IRI, made a peak at the 48th hour, and declined at the 72nd hour. Accumulation of ox-LDL was detected in the kidney tissue on the 24th, 48th, and 72nd hours of the renal IRI. Serum PON-1 levels have peaked on the 24th hour and then declined. This study demonstrates the accumulation of ox-LDL molecules in the renal tissues of the IRI model. Future strategies aimed to reduce the lipid peroxidation during the initial hours of renal IRI may be useful to prevent complications of ischemia.

  16. An experimental model of ischemia in rabbit hindlimb.

    PubMed Central

    Hong, J. H.; Bahk, Y. W.; Suh, J. S.; Kwak, B. K.; Shim, H. J.; Kim, J. S.; Kim, H. S.; Moon, Y. H.; Kim, S. J.; Chung, J. W.; Park, J. H.

    2001-01-01

    This study was performed to establish an experimental model of ischemia for the investigation of new treatment modality of limb-threatening ischemia. We produced ischemia in the hindlimbs of 8 New Zealand white rabbits. Under general anesthesia, the left femoral artery was exposed, freed, and excised from distal external iliac artery to proximal popliteal and saphenous arteries. And then both hindlimbs were serially examined to assess the ischemia according to the time table until postoperative 6 weeks. We assessed clinical observation, blood pressure, radioisotopic perfusion scan, and angiography. Clinical ischemic changes of the operated feet were observed in 63%. The blood pressure of left calves was measurable on postoperative day 3 (p<0.05, vs preoperative day 2) and then gradually increased to reach a plateau in postoperative week 6. Radioisotopic arterial perfusion showed similar profiles as in blood pressure. Angiography of ischemic hindlimbs demonstrated a few collateral vessels arising from the internal iliac artery with the reconstitution of the posterior tibial artery in postoperative week 2. In postoperative week 6, collaterals remained the same in number. However, these became dilated and tortuous and showed reconstitution in distal hindleg. In conclusion, this is a reproducible, measurable, and economical animal model of hind limb ischemia. PMID:11641535

  17. Establishment of a novel tick-Babesia experimental infection model

    PubMed Central

    Maeda, Hiroki; Hatta, Takeshi; Alim, M Abdul; Tsubokawa, Daigo; Mikami, Fusako; Matsubayashi, Makoto; Miyoshi, Takeharu; Umemiya-Shirafuji, Rika; Kawazu, Shin-ichiro; Igarashi, Ikuo; Mochizuki, Masami; Tsuji, Naotoshi; Tanaka, Tetsuya

    2016-01-01

    Ticks are potent vectors of many deadly human and animal pathogens. Tick-borne babesiosis is a well-recognized malaria-like disease that occurs worldwide and recently has attracted increased attention as an emerging zoonosis. Although the proliferation of Babesia organisms is essential in the vectors, their detailed lifecycle with time information for migration in ticks remains unknown. A novel study model for the elucidation of the migration speed of Babesia parasites in their vector tick, Haemaphysalis longicornis, has been developed using an artificial feeding system with quantitative PCR method. The detectable DNA of Babesia parasites gradually disappeared in the tick midgut at 1 day post engorgement (DPE), and in contrary increased in other organs. The results indicated that the Babesia parasite passed the H. longicornis midgut within 24 hours post engorgement, migrated to the hemolymph, and then proliferated in the organs except the midgut. This time point may be an important curfew for Babesia parasites to migrate in the tick lumen. We also visualized the Babesia parasites in the experimentally infected ticks and in their eggs using IFAT for detecting their cytoskeletal structure, which suggested the successful tick infection and transovarial transmission of the parasite. This model will shed light on the further understanding of tick-Babesia interactions. PMID:27841321

  18. Experimental Verification of Computational Models for Laminated Composites

    NASA Technical Reports Server (NTRS)

    Harris, Charles E.; Coats, Timothy W.; Glaessgen, Edward H.

    1999-01-01

    The objective of the research reported herein is to develop a progressive damage methodology capable of predicting the residual strength of continuous fiber-reinforced, laminated, polymer matrix composites with through-penetration damage. The fracture behavior of center-notch tension panels with thin crack-like slits was studied. Since fibers are the major load-carrying constituent in polymer matrix composites, predicting the residual strength of a laminate requires a criterion for fiber fracture. The effects on fiber strain due to other damage mechanisms such as matrix cracking and delaminations must also be modeled. Therefore, the research herein examines the damage mechanisms involved in translaminate fracture and identifies the toughening mechanisms responsible for damage growth resistance in brittle epoxy matrix systems. The mechanics of matrix cracking and fiber fracture are discussed as is the mathematical framework for the progressive damage model developed by the authors. The progressive damage analysis algorithms have been implemented into a general purpose finite element code developed by NASA, the Computational Structural Mechanics Testbed (COMET). Damage growth is numerically simulated and the analytical residual strength predictions are compared to experimental results for a variety of notched panel configurations and materials systems.

  19. Effectiveness and safety of iodopovidone in an experimental pleurodesis model

    PubMed Central

    Teixeira, Lisete R.; Vargas, Francisco S.; Puka, Juliana; Acencio, Milena M. P.; Antonangelo, Leila; Terra, Ricardo M.; Damico, Francisco M.; Pitta, Fabio G.; Marchi, Evaldo

    2013-01-01

    OBJECTIVES: Chemical pleurodesis is an important therapeutic tool to control recurrent malignant pleural effusion. Among the various sclerosing agents, iodopovidone is considered effective and safe. However, in a recent study, ocular changes were described after iodopovidone was used in recurrent pneumothorax. The aim of the study was to evaluate the efficacy and morbidity of iodopovidone pleurodesis in an experimental model. METHODS: New Zealand rabbits were submitted to intrapleural injection of iodopovidone at concentrations of 2%, 4% and 10%. Biochemical (lactic dehydrogenase, proteins, triiodothyronine, free thyroxine, urea and creatinine) and immunological (Interleukin-8 [IL-8], VEGF and TGFβ) parameters were measured in the pleural fluid and blood. After 1, 3, 7, 14 and 28 days, groups of animals were euthanized, and macro- (pleura) and microscopic (pleura and retina) analyses were performed. RESULTS: An early pleural inflammatory response with low systemic repercussion was observed without corresponding changes in thyroid or renal function. The higher concentrations (4% and 10%) correlated with greater initial exudation, and maximum pleural thickening was observed after 28 days. No changes were observed in the retinal pigment epithelium of the rabbits. CONCLUSION: Iodopovidone is considered to be an effective and safe sclerosing agent in this animal model. However, its efficacy, tolerance and safety in humans should be further evaluated. PMID:23778345

  20. Experimental osteonecrosis: development of a model in rodents administered alendronate.

    PubMed

    Conte, Nicolau; Spolidorio, Luis Carlos; Andrade, Cleverton Roberto de; Esteves, Jônatas Caldeira; Marcantonio, Elcio

    2016-08-22

    The main objective of this study was to cause bisphosphonate-related osteonecrosis of the jaws to develop in a rodent model. Adult male Holtzman rats were assigned to one of two experimental groups to receive alendronate (AL; 1 mg/kg/week; n = 6) or saline solution (CTL; n = 6). After 60 days of drug therapy, all animals were subjected to first lower molar extraction, and 28 days later, animals were euthanized. All rats treated with alendronate developed osteonecrosis, presenting as ulcers and necrotic bone, associated with a significant infection process, especially at the inter-alveolar septum area and crestal regions. The degree of vascularization, the levels of C-telopeptide cross-linked collagen type I and bone-specific alkaline phosphatase, as well as the bone volume were significantly reduced in these animals. Furthermore, on radiographic analysis, animals treated with alendronate presented evident sclerosis of the lamina dura of the lower first molar alveolar socket associated with decreased radiographic density in this area. These findings indicate that the protocol developed in the present study opens new perspectives and could be a good starting model for future property design.

  1. Polarisers in the focal domain: Theoretical model and experimental validation.

    PubMed

    Martínez-Herrero, Rosario; Maluenda, David; Juvells, Ignasi; Carnicer, Artur

    2017-02-13

    Polarisers are one of the most widely used devices in optical set-ups. They are commonly used with paraxial beams that propagate in the normal direction of the polariser plane. Nevertheless, the conventional projection character of these devices may change when the beam impinges a polariser with a certain angle of incidence. This effect is more noticeable if polarisers are used in optical systems with a high numerical aperture, because multiple angles of incidence have to be taken into account. Moreover, the non-transverse character of highly focused beams makes the problem more complex and strictly speaking, the Malus' law does not apply. In this paper we develop a theoretical framework to explain how ideal polarisers affect the behavior of highly focused fields. In this model, the polarisers are considered as birefringent plates, and the vector behaviour of focused fields is described using the plane-wave angular spectrum approach. Experiments involving focused fields were conducted to verify the theoretical model and a satisfactory agreement between theoretical and experimental results was found.

  2. Development of Experimental Tissue Models for Blast Injury

    NASA Astrophysics Data System (ADS)

    Butler, Benjamin; Bo, Chiara; Williams, Alun; Jardine, Andy; Brown, Katherine

    2013-06-01

    There is a pressing need to better understand the relationship between the intensity of a blast wave and the clinical consequences for victims of an explosion. In order to quantitatively study how these factors correlate with one another, blast injury tissue models are being developed. Sections of larynx, trachea and pulmonary tissue were excised from a recently sacrificed pig and maintained on ice prior to testing. The samples were subjected to strain rates of between 0.001 s-1 and 1000 s-1 in the laboratory by using a Split Hopkinson Pressure Bar and quasi-static testing apparatus. During high strain rate testing, samples were housed in a polycarbonate chamber which permitted experimentation on tissue held in fluid. Data were analysed using 1, 2 and 3 wave analysis software in Matlab to yield information about the material properties of both undamaged and damaged tissues. In addition, macroscopic changes in tissue organization were also visualized using histopathological techniques. This work is being extended to cellular and animal models to derive more detailed information about the underlying molecular changes relating to blast-induced damage and repair. The Royal British Legion Centre for Blast Injury Studies.

  3. Polarisers in the focal domain: Theoretical model and experimental validation

    PubMed Central

    Martínez-Herrero, Rosario; Maluenda, David; Juvells, Ignasi; Carnicer, Artur

    2017-01-01

    Polarisers are one of the most widely used devices in optical set-ups. They are commonly used with paraxial beams that propagate in the normal direction of the polariser plane. Nevertheless, the conventional projection character of these devices may change when the beam impinges a polariser with a certain angle of incidence. This effect is more noticeable if polarisers are used in optical systems with a high numerical aperture, because multiple angles of incidence have to be taken into account. Moreover, the non-transverse character of highly focused beams makes the problem more complex and strictly speaking, the Malus’ law does not apply. In this paper we develop a theoretical framework to explain how ideal polarisers affect the behavior of highly focused fields. In this model, the polarisers are considered as birefringent plates, and the vector behaviour of focused fields is described using the plane-wave angular spectrum approach. Experiments involving focused fields were conducted to verify the theoretical model and a satisfactory agreement between theoretical and experimental results was found. PMID:28191817

  4. Experimental Investigation and Modeling of Copper Smelting Slags

    NASA Astrophysics Data System (ADS)

    Starodub, Konstantin; Kuminova, Yaroslava; Dinsdale, Alan; Cheverikin, Vladimir; Filichkina, Vera; Saynazarov, Abdukahhar; Khvan, Alexandra; Kondratiev, Alex

    2016-10-01

    Effective extraction of copper from sulfide ores requires careful operation of a copper smelter, which in turn depends very much on chemistry of the feed and resulted slag and matte. For example, chemical composition of copper smelting slags has to be in a certain range to ensure that their properties are within specific limits. Disobeying these rules may lead to complications in smelting operation, poor quality of the copper products, and premature shutdown of the copper smelter. In the present paper the microstructure and phase composition of slags from the Almalyk copper flash smelter were investigated experimentally and then modeled thermodynamically to evaluate potential ways of improvement and optimization of the copper smelting process and its products. The slag samples were taken at different stages of the copper smelting process: on slag tapping, after slag transportation to a deposition site, and at the site. Experimental investigation included the XRD, XRF, and SEM techniques, which were also confirmed by the traditional wet chemistry analysis. Thermodynamic modeling was carried out using thermochemical software package MTDATA, which enables thermodynamic and physical properties of the matte, slag, and gas phases to be calculated in a wide range of temperatures, pressures, and chemical compositions. In addition, slag viscosities and corresponding matte settling rates were estimated using the modified Urbain and Utigard-Warczok models, and the Hadamard-Rybczynski equation, respectively. It was found that the copper content in the slags may vary significantly depending on the location of slag sampling. Cu was found to be present as sulfide particles, almost no Cu was found to be dissolved in the slag. Analysis of microstructure and phase composition showed that major phase found in the samples is fayalite, while other phases are complex spinels (based on magnetite), different sulfides, and a glass-like phase. Thermodynamic calculations demonstrated the

  5. Numerical modeling and experimental testing of a solar grill

    SciTech Connect

    Olwi, I.; Khalifa, A. )

    1993-02-01

    The sun provides a free, nonpolluting and everlasting source of energy. Considerable research has been carried out to utilize solar energy for purposes such as water heating, high temperature ovens, and conversion to electrical energy. One of the interesting forms for utilizing solar energy is cooking. The main disadvantage of solar energy systems has been the low efficiency attained in most of its practical applications. It is expected, however, that due to continuing decreases in the availability of other energy sources such as oil and coal, along with the safety problems associated with nuclear energy, man's need for utilization of solar energy will increase, thus leading him to find the ways and means to develop adequate and efficient solar-powered systems. In camps, where tents are used to accommodate people, cooking is done via conventional gas stoves. This usually takes place in extremely crowded areas which become highly fireprone. Solar oven cookers seem to be a viable alternative considering both economy and safety. Among the various forms of solar cookers, the oven-type solar cooker is known to be the best in terms of efficiency. One of the most practical and efficient forms of solar oven cookers is the outdoor portable solar grill (Bar-B-Q), developed by Khalifa et al. The solar grill is a light and portable unit that utilizes solar energy to grill meat. One of the best types of grilling with this cooker is the well-known Shish Kebab or Bar-B-Q. A detailed description for the design of the solar grill is provided as follows. This paper is aimed at providing experimental results and formulating a numerical model for the solar grill. Results of the two approaches are then compared to verify the validity of the numerical simulation. An experimental and theoretical investigation was conducted on the solar grill in order to study the factors that affect its design and performance.

  6. [Laboratory animal anaesthesia: influence of anaesthetic protocols on experimental models].

    PubMed

    Bazin, J-E; Constantin, J-M; Gindre, G

    2004-08-01

    different animal species and human and animals about the effects of anaesthetic agents are very hazardous. Great differences exist between the effects observed in vitro and in whole animals. The effects of the anaesthetics could be totally different if they are used alone or in association. The same anaesthetic could have opposite effects from an organ to another. For results validation, the anaesthesia side effects (hypoventilation, hypotension, cooling em leader ) have to be minimized. All new experimental models should require discussing the possible interferences between anaesthesia and results and to compare results obtained with different anaesthetic protocols.

  7. Experimental and modelling studies for the validation of the mechanistic basis of the Local Effect Model

    NASA Astrophysics Data System (ADS)

    Tommasino, F.

    2016-03-01

    This review will summarize results obtained in the recent years applying the Local Effect Model (LEM) approach to the study of basic radiobiological aspects, as for instance DNA damage induction and repair, and charged particle track structure. The promising results obtained using different experimental techniques and looking at different biological end points, support the relevance of the LEM approach for the description of radiation effects induced by both low- and high-LET radiation. Furthermore, they suggest that nowadays the appropriate combination of experimental and modelling tools can lead to advances in the understanding of several open issues in the field of radiation biology.

  8. Experimental Investigation of the NASA Common Research Model

    NASA Technical Reports Server (NTRS)

    Rivers, Melissa B.; Dittberner, Ashley

    2010-01-01

    An experimental aerodynamic investigation of the NASA Common Research Model has been conducted in the NASA NTF (National Transonic Facility). Data have been obtained at chord Reynolds numbers of 5, 19.8 and 30 million for the WB and WBT0 configurations. Data have also been obtained at a chord Reynolds number of 5 million for the WBNP, WBT+2 and WBT-2 configurations. Force and moment, surface pressure and surface flow visualization data were obtained but only the force and moment data are presented herein. Model deformation measurements, aeroelastic, nacelle/pylon Reynolds number and tail effects have been assessed. The model deformation measurements showed more twist as you go out the wing span, with a break in the high q(sub infinity) data close to CL = 0.6 which is consistent with separation near the tip. Increases in dynamic pressure give an increase in pitching moment and drag and a decrease in lift for the WB and WBT0 configuration at Mach = 0.7, 0.85 and 0.87. The addition of a nacelle/pylon gave an increase in drag, decrease in lift and a less nose down pitching moment around the design lift condition of 0.5. Increases in chord Reynolds number have been found to follow the normal Reynolds number trends except at the 19.8 million low q(sub infinity) cases. The abnormality of the 19.8 million low q(sub infinity) cases is being investigated. The tail effects also follow the expected trends. All of the data shown fall within the 2-sigma limits for repeatability.

  9. In-Body Network Biomedical Applications: From Modeling to Experimentation.

    PubMed

    Loscri, Valeria; Matekovits, Ladislau; Peter, Ildiko; Vegni, Anna Maria

    2016-01-01

    Innovative diagnostic approaches and therapies are more and more based on the use of injections or oral delivery of nanoparticle sized substances. For a better understanding of the overall phenomena, aiming to facilitate a safe application at large scale, the development of accurate models and analysis techniques are required. These techniques take into consideration different aspects of the overall process: accurate numerical modeling of the different phases of the nanoparticles in the body, and knowledge of the local environment, that can be varying very fast within a short-range in the body itself. Such aspects should be taken into account to correctly predict the amount of drug and its timely release for the specific disease. Deep and accurate analysis of the interaction between the nanoparticles and the biological fluid where the nanoparticles are immersed is mandatory for an efficient correlation of all these aspects. Because of their biocompatibility, in this paper, we focus our attention on systems of Titanium (Ti), and its oxide (e.g., TiO2), given their specific features in terms of density, lack of cytotoxic effects, etc. Specifically, we present the study and design of an in-body system by characterizing each of the emission, diffusion, and reception processes with a proper realistic model. The theoretical investigation is further supported by experimental study of the morphology and other important characteristics (e.g., the pH of the particles, and thermal stability) of TiO2 systems when immersed in a Ringer solution, in order to derive important information related to their potential toxicity inside the human body.

  10. Thermal infrared spectroscopy and modeling of experimentally shocked plagioclase feldspars

    USGS Publications Warehouse

    Johnson, J. R.; Horz, F.; Staid, M.I.

    2003-01-01

    Thermal infrared emission and reflectance spectra (250-1400 cm-1; ???7???40 ??m) of experimentally shocked albite- and anorthite-rich rocks (17-56 GPa) demonstrate that plagioclase feldspars exhibit characteristic degradations in spectral features with increasing pressure. New measurements of albite (Ab98) presented here display major spectral absorptions between 1000-1250 cm-1 (8-10 ??m) (due to Si-O antisymmetric stretch motions of the silica tetrahedra) and weaker absorptions between 350-700 cm-1 (14-29 ??m) (due to Si-O-Si octahedral bending vibrations). Many of these features persist to higher pressures compared to similar features in measurements of shocked anorthite, consistent with previous thermal infrared absorption studies of shocked feldspars. A transparency feature at 855 cm-1 (11.7 ??m) observed in powdered albite spectra also degrades with increasing pressure, similar to the 830 cm-1 (12.0 ??m) transparency feature in spectra of powders of shocked anorthite. Linear deconvolution models demonstrate that combinations of common mineral and glass spectra can replicate the spectra of shocked anorthite relatively well until shock pressures of 20-25 GPa, above which model errors increase substantially, coincident with the onset of diaplectic glass formation. Albite deconvolutions exhibit higher errors overall but do not change significantly with pressure, likely because certain clay minerals selected by the model exhibit absorption features similar to those in highly shocked albite. The implication for deconvolution of thermal infrared spectra of planetary surfaces (or laboratory spectra of samples) is that the use of highly shocked anorthite spectra in end-member libraries could be helpful in identifying highly shocked calcic plagioclase feldspars.

  11. Early differentiation of the Moon: Experimental and modeling studies and experimental and modeling studies of massif anorthosites

    NASA Technical Reports Server (NTRS)

    Longhi, John

    1994-01-01

    NASA grant NAG9-329 was in effect from 3/1/89 to 8/31/94, the last 18 months being a no-cost extension. While the grant was in effect, the P.I., coworkers, and students gave 22 talks and poster sessions at professional meetings, published 12 articles in referred journals (one more is in press, and another is in review), and edited 2 workshop reports relevant to this project. Copies of all the publications are appended to this report. The major accomplishments during the grant period have derived from three quarters: 1) the application of quantitative models of fractional crystallization and partial melting to various problems in planetary science, such as the petrogenesis of picritic glasses and mare basalts and the implications of the SNC meteorites for martian evolution; 2) an experimental study of silicate liquid immiscibility relevant to early lunar differentiation and the petrogenesis of evolved highlands rocks; and 3) experimental studies of massif anorthosites and related rocks that provide terrestrial analogs for the proposed origin of lunar anorthosites by multistage processes. The low-pressure aspects of the quantitative models were developed by the P.I. in the 1980s with NASA support and culminated with a paper comparing the crystallization of terrestrial and lunar lavas. The basis for the high-pressure modifications to the quantitative models is a data set gleaned from high pressure melting experiments done at Lamont and is supplemented by published data from other labs that constrain the baric and compositional dependences of various liquidus phase boundaries such as olivine/orthopyroxene, relevant to the melting of the mantles of the terrestrial planets. With these models it is possible to predict not only the thermal and compositional evolution of magmatic liquids ranging in composition from lumar mare basalt to terrestrial calc-alkaline basalts, but also the small increments of fractional melting that are produced when mantle rises adiabatically

  12. The use of experimental structures to model protein dynamics.

    PubMed

    Katebi, Ataur R; Sankar, Kannan; Jia, Kejue; Jernigan, Robert L

    2015-01-01

    The number of solved protein structures submitted in the Protein Data Bank (PDB) has increased dramatically in recent years. For some specific proteins, this number is very high-for example, there are over 550 solved structures for HIV-1 protease, one protein that is essential for the life cycle of human immunodeficiency virus (HIV) which causes acquired immunodeficiency syndrome (AIDS) in humans. The large number of structures for the same protein and its variants include a sample of different conformational states of the protein. A rich set of structures solved experimentally for the same protein has information buried within the dataset that can explain the functional dynamics and structural mechanism of the protein. To extract the dynamics information and functional mechanism from the experimental structures, this chapter focuses on two methods-Principal Component Analysis (PCA) and Elastic Network Models (ENM). PCA is a widely used statistical dimensionality reduction technique to classify and visualize high-dimensional data. On the other hand, ENMs are well-established simple biophysical method for modeling the functionally important global motions of proteins. This chapter covers the basics of these two. Moreover, an improved ENM version that utilizes the variations found within a given set of structures for a protein is described. As a practical example, we have extracted the functional dynamics and mechanism of HIV-1 protease dimeric structure by using a set of 329 PDB structures of this protein. We have described, step by step, how to select a set of protein structures, how to extract the needed information from the PDB files for PCA, how to extract the dynamics information using PCA, how to calculate ENM modes, how to measure the congruency between the dynamics computed from the principal components (PCs) and the ENM modes, and how to compute entropies using the PCs. We provide the computer programs or references to software tools to accomplish each step

  13. Callithrix penicillata: a feasible experimental model for dengue virus infection.

    PubMed

    Ferreira, Milene Silveira; de Castro, Paulo Henrique Gomes; Silva, Gilmara Abreu; Casseb, Samir Mansur Moraes; Dias Júnior, Antônio Gregório; Rodrigues, Sueli Guerreiros; Azevedo, Raimunda do Socorro da Silva; Costa e Silva, Matheus Fernandes; Zauli, Danielle Alves Gomes; Araújo, Márcio Sobreira Silva; Béla, Samantha Ribeiro; Teixeira-Carvalho, Andréa; Martins-Filho, Olindo Assis; Vasconcelos, Pedro Fernando da Costa

    2014-01-01

    Although the murine models have the feasibility to reproduce some signs of dengue Virus (DENV) infection, the use of isogenic hosts with polarized immune response patterns does not reproduce the particularities of human disease. Our goal was to investigate the kinetics of peripheral blood biomarkers in immunocompetent Callithrix penicillata non-human primates subcutaneously infected with DENV-3. The viral load of infected animals was determinated by quantitative real time PCR. Measurements of DENV-3/IgM were performed, and several parameters were assessed by hemogram: red blood cells count, hemoglobin, hematocrit, white blood cells count, neutrophils, monocytes, lymphocytes, and platelets count. The coagulogram was performed by prothrombin time (PT), and activated partial thromboplastin time (APTT) assays. The renal function was monitored by urea and creatinine, and the liver function by the aspartate (AST), and alanine (ALT) aminotransferases. Also, the level of the cytokines IL-6, TNF-α, IL-2, IFN-γ, IL-4 and IL-5 was quantified during the experimental study. Data analysis was performed considering relevant differences when baseline fold changes were found outside from 0.75 to 1.5 range. Our data demonstrated that infected animals presented relevant signs of dengue disease, including peaks of viremia at 5 days-post-infection (dpi), peaks of anti-DENV-3 IgM at 15 dpi and hemaglutination inhibition assay (HIA) from 15 to at 60 dpi. Despite early monocytosis, slight neutrophilia and lymphocytosis, animals developed persistent leucopenia starting at 4 dpi. Anemia episodes were steady at 3-4 dpi. Patent thrombocytopenia was observed from 1 to 15 dpi with sporadic decrease of APTT. A substantial increase of ALT and AST was observed with higher peak at 4 dpi. Moreover, early increases of TNF-alpha and IFN-gamma besides late increase of IFN-gamma were observed. The analysis of biomarkers network pointed out two relevant strong axes during early stages of dengue fever

  14. The Use of Experimental Structures to Model Protein Dynamics

    PubMed Central

    Katebi, Ataur R.; Sankar, Kannan; Jia, Kejue; Jernigan, Robert L.

    2014-01-01

    Summary The number of solved protein structures submitted in the Protein Data Bank (PDB) has increased dramatically in recent years. For some specific proteins, this number is very high – for example, there are over 550 solved structures for HIV-1 protease, one protein that is essential for the life cycle of human immunodeficiency virus (HIV) which causes acquired immunodeficiency syndrome (AIDS) in humans. The large number of structures for the same protein and its variants include a sample of different conformational states of the protein. A rich set of structures solved experimentally for the same protein has information buried within the dataset that can explain the functional dynamics and structural mechanism of the protein. To extract the dynamics information and functional mechanism from the experimental structures, this chapter focuses on two methods – Principal Component Analysis (PCA) and Elastic Network Models (ENM). PCA is a widely used statistical dimensionality reduction technique to classify and visualize high-dimensional data. On the other hand, ENMs are well-established simple biophysical method for modeling the functionally important global motions of proteins. This chapter covers the basics of these two. Moreover, an improved ENM version that utilizes the variations found within a given set of structures for a protein is described. As a practical example, we have extracted the functional dynamics and mechanism of HIV-1 protease dimeric structure by using a set of 329 PDB structures of this protein. We have described, step by step, how to select a set of protein structures, how to extract the needed information from the PDB files for PCA, how to extract the dynamics information using PCA, how to calculate ENM modes, how to measure the congruency between the dynamics computed from the principal components (PCs) and the ENM modes, and how to compute entropies using the PCs. We provide the computer programs or references to software tools to

  15. A new apparatus for standardization of experimental burn models.

    PubMed

    Arda, Mehmet Surhan; Koçman, Atacan Emre; Söztutar, Erdem; Baksan, Bedri; Çetin, Cengiz

    2017-09-01

    Burns have severe economic burden for families and countries therefore its treatment modalities have utmost importance. Several study both experimental or clinic has been reported accordingly. Although contact burns were frequently used models, most of them were manually designed. The elapsed time was recorded only. However, the real time contact surface temperature (T) and weight force (WF) were fundamental characteristics of a burn model. The aim of this study is to create a standard burn model with recording real time variables on behalf of custom designed apparatus. A custom designed apparatus was manufactured in which the variables of real time T, WF and elapsed time could be set and record. A vertical angle was provided to ensure the applied WF. And hence, Sprague-Dawley rats were randomly divided into four groups: (1) Burned at 60±1°C with low WF(G60WFL), (2) Burned at 60±1°C with high WF(G60WFH), (3) Burned at 80±1°C with low WF(G80WFL), (4) Burned at 80±1°C with high WF(G80WFH). The healthy skin thickness and burn depth were measured. The percentage of burn depth to healthy skin was used for statistical analysis. Constant variables T and WF were achieved. The pressure applied on skin was not significant between low [G60WFL vs G80WFL, (p=0.1704)] and high [G60WFH vs G80WFH (p=0.2369)] WF groups. However the percentage of burn depth was increasing owing to applied WF in 60°C group [G60WFL vs G60WFH, (p=0.0125)] and in 80°C group [G80WFL vs G80WFH (p<0.0001)]. And also the percentage was significantly increasing owing to set T, in low WF group [G60WFL vs G80WFL (p<0.0001)] and high WF group [G60WFH vs G80WFH (p<0.0001)]. Besides neither T nor WF has priority. Without recording the real time T and WF, it is infeasible to achieve a standard burn model. For a standard depth of burn, variables should be under control, as if our custom designed apparatus. Copyright © 2017 Elsevier Ltd and ISBI. All rights reserved.

  16. Comparison of a tension leg platform response prediction model with experimental data

    SciTech Connect

    Gurley, K.R.; Kareem, A.

    1996-12-31

    A numerical model developed to efficiently predict the response of a tension leg platform under wind and wave loads in the frequency domain is examined in light of experimental data. Three studies are conducted in which model performance is compared to current state-of-the-art models, a simplified model, and two sets of experimental data. The wave diffraction and response analysis codes of the model under consideration are applied to a benchmark study in the literature and are found to be in close agreement with the state-of-the-art codes. The model is then applied to two sets of experimental data, the first of which accompanies the results of a simplified model to predict the experimental response. The current model compares favorably with the other response analysis codes under consideration. The model also matches well with experimental data, within the limitations of uncertainties in experimental procedures.

  17. Hydrothermal Oxidation of Fecal Sludge: Experimental Investigations and Kinetic Modeling

    PubMed Central

    2016-01-01

    Hydrothermal oxidation (HTO) provides an efficient technique to completely destroy wet organic wastes. In this study, HTO was applied to treat fecal sludge at well-defined experimental conditions. Four different kinetic models were adjusted to the obtained data. Among others, a distributed activation energy model (DAEM) was applied. A total of 33 experiments were carried out in an unstirred batch reactor with pressurized air as the oxidant at temperatures of <470 °C, oxygen-to-fuel equivalence ratios between 0 and 1.9, feed concentrations between 3.9 and 9.8 molTOC L–1 (TOC = total organic carbon), and reaction times between 86 and 1572 s. Decomposition of the fecal sludge was monitored by means of the conversion of TOC to CO2 and CO. In the presence of oxygen, ignition of the reaction was observed around 300 °C, followed by further rapid decomposition of the organic material. The TOC was completely decomposed to CO2 within 25 min at 470 °C and an oxygen-to-fuel equivalence ratio of 1.2. CO was formed as an intermediate product, and no other combustible products were found in the gas. At certain reaction conditions, the formation of unwanted coke and tarlike products occurred. The reaction temperature and oxygen-to-fuel equivalence ratio showed a significant influence on TOC conversion, while the initial TOC concentration did not. Conversion of TOC to CO2 could be well described with a first-order rate law and an activation energy of 39 kJ mol–1. PMID:28539700

  18. COMPUTATIONAL AND EXPERIMENTAL MODELING OF SLURRY BUBBLE COLUMN REACTORS

    SciTech Connect

    Paul Lam; Dimitri Gidaspow

    2000-09-01

    The objective if this study was to develop a predictive experimentally verified computational fluid dynamics (CFD) model for gas-liquid-solid flow. A three dimensional transient computer code for the coupled Navier-Stokes equations for each phase was developed. The principal input into the model is the viscosity of the particulate phase which was determined from a measurement of the random kinetic energy of the 800 micron glass beads and a Brookfield viscometer. The computed time averaged particle velocities and concentrations agree with PIV measurements of velocities and concentrations, obtained using a combination of gamma-ray and X-ray densitometers, in a slurry bubble column, operated in the bubbly-coalesced fluidization regime with continuous flow of water. Both the experiment and the simulation show a down-flow of particles in the center of the column and up-flow near the walls and nearly uniform particle concentration. Normal and shear Reynolds stresses were constructed from the computed instantaneous particle velocities. The PIV measurement and the simulation produced instantaneous particle velocities. The PIV measurement and the simulation produced similar nearly flat horizontal profiles of turbulent kinetic energy of particles. This phase of the work was presented at the Chemical Reaction Engineering VIII: Computational Fluid Dynamics, August 6-11, 2000 in Quebec City, Canada. To understand turbulence in risers, measurements were done in the IIT riser with 530 micron glass beads using a PIV technique. The results together with simulations will be presented at the annual meeting of AIChE in November 2000.

  19. Therapeutic blockade of Foxp3 in experimental breast cancer models.

    PubMed

    Moreno Ayala, Mariela A; Gottardo, María Florencia; Imsen, Mercedes; Asad, Antonela S; Bal de Kier Joffé, Elisa; Casares, Noelia; Lasarte, Juan José; Seilicovich, Adriana; Candolfi, Marianela

    2017-07-29

    Regulatory T cells (Tregs) impair the clinical benefit of cancer immunotherapy. To optimize the antitumor efficacy of therapeutic dendritic cell (DC) vaccines, we aimed to inhibit Foxp3, a transcription factor required for Treg function. Mice bearing established syngeneic LM3 and 4T1 breast tumors were treated with antitumor DC vaccines and a synthetic peptide (P60) that has been shown to inhibit Foxp3. Treatment with P60 improved the therapeutic efficacy of DC vaccines in these experimental models. In addition, monotherapy with P60 inhibited tumor growth in immunocompetent as well as in immuno-compromised animals bearing established tumors. We found expression of Foxp3 in human and murine breast tumor cells. P60 inhibited IL-10 secretion in breast cancer cells that expressed Foxp3. Our results suggest that Foxp3 blockade improves the therapeutic efficacy of DC vaccines by inhibition of Tregs and through a direct antitumor effect. This strategy could prove useful to neutralize the immunosuppressive microenvironment and to boost antitumor immunity in breast cancer.

  20. Zika virus congenital syndrome: experimental models and clinical aspects.

    PubMed

    Polonio, Carolina Manganeli; de Freitas, Carla Longo; Zanluqui, Nagela Ghabdan; Peron, Jean Pierre Schatzmann

    2017-01-01

    Viral infections have long been the cause of severe diseases to humans, increasing morbidity and mortality rates worldwide, either in rich or poor countries. Yellow fever virus, H1N1 virus, HIV, dengue virus, hepatitis B and C are well known threats to human health, being responsible for many million deaths annually, associated to a huge economic and social cost. In this context, a recently introduced flavivirus in South America, called Zika virus (ZIKV), led the WHO to declare in February 1st 2016 a warning on Public Health Emergency of International Concern (PHEIC). ZIKV is an arbovirus of the Flaviviridae family firstly isolated from sentinels Rhesus sp. monkeys at the Ziika forest in Uganda, Africa, in 1947. Lately, the virus has well adapted to the worldwide spread Aedes aegypti mosquito, the vector for DENV, CHIKV, YFV and many others. At first, it was not considered a threat to human health, but everything changed when a skyrocketing number of babies born with microcephaly and adults with Guillain-Barré syndrome were reported, mainly in northeastern Brazil. It is now well established that the virus is responsible for the so called congenital Zika syndrome (CZS), whose most dramatic features are microcephaly, arthrogryposis and ocular damage. Thus, in this review, we provide a brief discussion of these main clinical aspects of the CZS, correlating them with the experimental animal models described so far.

  1. The rat caudal nerves: a model for experimental neuropathies.

    PubMed

    Schaumburg, Herbert H; Zotova, Elena; Raine, Cedric S; Tar, Moses; Arezzo, Joseph

    2010-06-01

    This study provides a detailed investigation of the anatomy of the rat caudal nerve along its entire length, as well as correlated nerve conduction measures in both large and small diameter axons. It determines that rodent caudal nerves provide a simple, sensitive experimental model for evaluation of the pathophysiology of degeneration, recovery, and prevention of length-dependent distal axonopathy. After first defining the normal anatomy and electrophysiology of the rat caudal nerves, acrylamide monomer, a reliable axonal toxin, was administered at different doses for escalating time periods. Serial electrophysiological recordings were obtained, during intoxication, from multiple sites along caudal and distal sciatic nerves. Multiple sections of the caudal and sciatic nerves were examined with light and electron microscopy. The normal distribution of conduction velocities was determined and acrylamide-induced time- and dose-related slowing of velocities at the vulnerable ultraterminal region was documented. Degenerative morphological changes in the distal regions of the caudal nerves appeared well before changes in the distal sciatic nerves. Our study has shown that (1) rat caudal nerves have a complex neural structure that varies along a distal-to-proximal gradient and (2) correlative assessment of both morphology and electrophysiology of rat caudal nerves is easily achieved and provides a highly sensitive index of the onset and progression of the length-dependent distal axonopathy.

  2. Experimental Classical Flutter Reesults of a Composite Advanced Turboprop Model

    NASA Technical Reports Server (NTRS)

    Mehmed, O.; Kaza, K. R. V.

    1986-01-01

    Experimental results are presented that show the effects of blade pitch angle and number of blades on classical flutter of a composite advanced turboprop (propfan) model. An increase in the number of blades on the rotor or the blade pitch angle is destablizing which shows an aerodynamic coupling or cascade effect between blades. The flutter came in suddenly and all blades vibrated at the same frequency but at different amplitudes and with a common predominant phase angle between consecutive blades. This further indicates aerodynamic coupling between blades. The flutter frequency was between the first two blade normal modes, signifying an aerodynamic coupling between the normal modes. Flutter was observed at all blade pitch angles from small to large angles-of-attack of the blades. A strong blade response occurred, for four blades at the two-per-revolution (2P) frequency, when the rotor speed was near the crossing of the flutter mode frequency and the 2P order line. This is because the damping is low near the flutter condition and the interblade phase angle of the flutter mode and the 2P response are the same.

  3. Neovascular growth in an experimental alkali corneal burn model.

    PubMed

    Figueroa-Ortiz, L C; Martín Rodríguez, O; García-Ben, A; García-Campos, J

    2014-08-01

    To analyse the length and area of corneal surface occupied by vessels, and their location in an experimental model of alkali burn-induced corneal neovascularization. An injury to the central cornea of the right eye in 91 Sprague-Dawley rats was induced using a silver nitrate pencil. The rats were divided in 7 groups that were sacrificed 2, 4, 6, 8, 10, 12 and 14 days post-injury, and then perfused with a mixture of Chinese ink in PBS -phosphate buffer saline-. Corneas were flat-mounted processed and divided in 4 quadrants. Corneal neovascular growth parameters (length and area) and the location of these vessels were performed blind. The results were statistically analysed. Neovascular growth was observed from day 2, reaching its maximum peak in length and area on the 12th day post-injury. A slight reduction in corneal neovascularization was observed after this day. The vessels were initially located in the middle third of the stroma and tended to be observed in the anterior third during the course of the experiment. Neovascularisation was observed on day 2 post-injury in all sectors of corneal surface. Neovascular growth was uniform during the experiment. Neovessels were located in the middle and anterior third of the cornea. Copyright © 2012 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

  4. Atomistic modeling at experimental strain rates and timescales

    NASA Astrophysics Data System (ADS)

    Yan, Xin; Cao, Penghui; Tao, Weiwei; Sharma, Pradeep; Park, Harold S.

    2016-12-01

    Modeling physical phenomena with atomistic fidelity and at laboratory timescales is one of the holy grails of computational materials science. Conventional molecular dynamics (MD) simulations enable the elucidation of an astonishing array of phenomena inherent in the mechanical and chemical behavior of materials. However, conventional MD, with our current computational modalities, is incapable of resolving timescales longer than microseconds (at best). In this short review article, we briefly review a recently proposed approach—the so-called autonomous basin climbing (ABC) method—that in certain instances can provide valuable information on slow timescale processes. We provide a general summary of the principles underlying the ABC approach, with emphasis on recent methodological developments enabling the study of mechanically-driven processes at slow (experimental) strain rates and timescales. Specifically, we show that by combining a strong physical understanding of the underlying phenomena, kinetic Monte Carlo, transition state theory and minimum energy pathway methods, the ABC method has been found to be useful in a variety of mechanically-driven problems ranging from the prediction of creep-behavior in metals, constitutive laws for grain boundary sliding, void nucleation rates, diffusion in amorphous materials to protein unfolding. Aside from reviewing the basic ideas underlying this approach, we emphasize some of the key challenges encountered in our own personal research work and suggest future research avenues for exploration.

  5. Effects of benidipine in a rat model for experimental angina.

    PubMed

    Ikeda, Jun-ichi; Matsubara, Masahiro; Yao, Kozo

    2006-12-01

    To compare the antianginal effects of 1,4-dihydropyridine-type calcium-channel blockers, we evaluated the effects of benidipine, amlodipine, nifedipine, and efonidipine on vasopressin-induced myocardial ischemia in rats, an experimental model of angina. Intravenous administration of benidipine (3 microg/kg), amlodipine (1000 microg/kg), and nifedipine (100 microg/kg) suppressed the vasopressin-induced S-wave depression, an index of myocardial ischemia. Efonidipine (100 microg/kg, i.v.) tended to inhibit the S-wave depression. At the antianginal dose of each drug, amlodipine, nifedipine, and efonidipine decreased blood pressure significantly, whereas benidipine had little effect on blood pressure at a dose of 3 microg/kg. These results indicate that benidipine, unlike the other 1,4-dihydropyridine-type calcium-channel blockers examined in this study, inhibits vasopressin-induced coronary vasospasm with fewer undesirable effects such as hypotension in rats, suggesting that benidipine may be useful in the treatment of angina pectoris.

  6. An Experimental Model for Resistance Exercise in Rodents

    PubMed Central

    Nicastro, Humberto; Zanchi, Nelo Eidy; da Luz, Claudia Ribeiro; Chaves, Daniela Fojo Seixas; Lancha, Antonio Herbert

    2012-01-01

    This study aimed to develop an equipment and system of resistance exercise (RE), based on squat-type exercise for rodents, with control of training variables. We developed an operant conditioning system composed of sound, light and feeding devices that allowed optimized RE performance by the animal. With this system, it is not necessary to impose fasting or electric shock for the animal to perform the task proposed (muscle contraction). Furthermore, it is possible to perform muscle function tests in vivo within the context of the exercise proposed and control variables such as intensity, volume (sets and repetitions), and exercise session length, rest interval between sets and repetitions, and concentric strength. Based on the experiments conducted, we demonstrated that the model proposed is able to perform more specific control of other RE variables, especially rest interval between sets and repetitions, and encourages the animal to exercise through short-term energy restriction and “disturbing” stimulus that do not promote alterations in body weight. Therefore, despite experimental limitations, we believe that this RE apparatus is closer to the physiological context observed in humans. PMID:22496606

  7. Phage therapy of staphylococcal chronic osteomyelitis in experimental animal model.

    PubMed

    Kishor, Chandan; Mishra, Raghvendra Raman; Saraf, Shyam K; Kumar, Mohan; Srivastav, Arvind K; Nath, Gopal

    2016-01-01

    Methicillin resistant Staphylococcus aureus (MRSA) are the commonest cause of osteomyelitis. The aim of this study was to evaluate the role of an alternative therapy i.e. application of S. aureus specific bacteriophages in cases of osteomyelitis caused by MRSA in animal model. Twenty two rabbits were included in this study. The first two rabbits were used to test the safety of phage cocktail while the remaining 20 rabbits were divided into three groups; group A (n=4) to assess the establishment of osteomyelitis; group B (n=4) osteomyelitis developed but therapy started only after six weeks; and group C (n=12) osteomyelitis developed and therapy started after three weeks. Groups B and C rabbits were treated with four doses of cocktail of seven virulent bacteriophages at the interval of 48 h. Comparison between three groups was made on the basis of observation of clinical, radiological, microbiological, and histopathological examinations. Experimental group rabbits recovered from the illness in the subsequent two weeks of the therapy. Appetite and activity of the rabbits improved, local oedema, erythema and induration subsided. There were minimal changes associated with osteomyelitis in X-ray and histopathology also showed no signs of infection with new bone formation. Control B group rabbits also recovered well from the infection. The present study shows a potential of phage therapy to treat difficult infections caused by multidrug resistant bacteria.

  8. Triptolide ameliorates colonic fibrosis in an experimental rat model

    PubMed Central

    TAO, QINGSONG; WANG, BAOCHAI; ZHENG, YU; LI, GUANWEI; REN, JIANAN

    2015-01-01

    Triptolide is known to exert anti-inflammatory and immunomodulatory activities; however, its impact on intestinal fibrosis has not been previously examined. Based on our previous studies of the suppressive activity of triptolide on human colonic subepithelial myofibroblasts and the therapeutic efficacy of triptolide in Crohn’s disease, it was hypothesized that triptolide may have beneficial effects on intestinal fibrosis. In the present study, colonic fibrosis was induced in rats by 6 weekly repeated administration with a low-dose of 2,4,6-trinitrobenzene sulfonic acid (TNBS) and was then treated with triptolide or PBS daily (control) simultaneously. Extracellular matrix (ECM) deposition in the colon was examined with image analysis of Masson Trichrome staining. Total collagen levels in colonic homogenates were measured by a Sircol assay. Collagen Iα1 transcripts and collagen I protein were measured ex vivo in the isolated colonic subepithelial myofibroblasts by reverse transcription-quantitative polymerase chain reaction and immunoblot analysis, respectively. The results indicated that triptolide decreased ECM deposition and collagen production in the colon, and inhibited collagen Iα1 transcripts and collagen I protein expression in the isolated subepithelial myofibroblasts of the rats with colonic fibrosis. In conclusion, triptolide ameliorates colonic fibrosis in the experimental rat model, suggesting triptolide may be a promising compound for inflammatory bowel disease treatment. PMID:25845760

  9. Double piezoelectric energy harvesting cell: modeling and experimental verification

    NASA Astrophysics Data System (ADS)

    Wang, Xianfeng; Shi, Zhifei

    2017-06-01

    In this paper, a novel energy transducer named double piezoelectric energy harvesting cell (DPEHC) consisting of two flex-compressive piezoelectric energy harvesting cells (F-C PEHCs) is proposed. At the very beginning, two F-C PEHCs, a kind of cymbal type energy transducer, are assembled together sharing the same end just in order to be placed steady. However, throughout an open-circuit voltage test, additional energy harvesting performance of the DPEHC prototype appears. Taking the interaction between the two F-C PEHCs into account, a mechanical model for analyzing the DPEHC is established. The electric output of the DPEHC under harmonic excitation is obtained theoretically and verified experimentally, and good agreement is found. In addition, as an inverse problem, the method for identifying the key mechanical parameters of the DPEHC is recommended. Finally, the additional energy harvesting performance of the DPEHC is quantitatively discussed. Numerical results show that the additional energy harvesting performance of the DPEHC is correlated with the key mechanical parameters of the DPEHC. For the present DPEHC prototype, the energy harvesting addition is over 400% compared with two independent F-C PEHCs under the same load condition.

  10. Comparison of Laboratory Experimental Data to XBeach Numerical Model Output

    NASA Astrophysics Data System (ADS)

    Demirci, Ebru; Baykal, Cuneyt; Guler, Isikhan; Sogut, Erdinc

    2016-04-01

    generating data sets for testing and validation of sediment transport relationships for sand transport in the presence of waves and currents. In these series, there is no structure in the basin. The second and third series of experiments were designed to generate data sets for development of tombolos in the lee of detached 4m-long rubble mound breakwater that is 4 m from the initial shoreline. The fourth series of experiments are conducted to investigate tombolo development in the lee of a 4m-long T-head groin with the head section in the same location of the second and the third tests. The fifth series of experiments are used to investigate tombolo development in the lee of a 3-m-long rubble-mound breakwater positioned 1.5 m offshore of the initial shoreline. In this study, the data collected from the above mentioned five experiments are used to compare the results of the experimental data with XBeach numerical model results, both for the "no-structure" and "with-structure" cases regarding to sediment transport relationships in the presence of only waves and currents as well as the shoreline changes together with the detached breakwater and the T-groin. The main purpose is to investigate the similarities and differences between the laboratory experimental data behavior with XBeach numerical model outputs for these five cases. References: Baykal, C., Sogut, E., Ergin, A., Guler, I., Ozyurt, G.T., Guler, G., and Dogan, G.G. (2015). Modelling Long Term Morphological Changes with XBeach: Case Study of Kızılırmak River Mouth, Turkey, European Geosciences Union, General Assembly 2015, Vienna, Austria, 12-17 April 2015. Gravens, M.B. and Wang, P. (2007). "Data report: Laboratory testing of longshore sand transport by waves and currents; morphology change behind headland structures." Technical Report, ERDC/CHL TR-07-8, Coastal and Hydraulics Laboratory, US Army Engineer Research and Development Center, Vicksburg, MS. Roelvink, D., Reniers, A., van Dongeren, A., van Thiel de

  11. Desorption of plutonium from montmorillonite: An experimental and modeling study

    NASA Astrophysics Data System (ADS)

    Begg, James D.; Zavarin, Mavrik; Kersting, Annie B.

    2017-01-01

    Desorption of plutonium (Pu) will likely control the extent to which it is transported by mineral colloids. We evaluated the adsorption/desorption behavior of Pu on SWy-1 montmorillonite colloids at pH 4, pH 6, and pH 8 using batch adsorption and flow cell desorption experiments. After 21 days adsorption, Pu(IV) affinity for montmorillonite displayed a pH dependency, with Kd values highest at pH 4 and lowest at pH 8. The pH 8 experiment was further allowed to equilibrate for 6 months and showed an increase in Kd, indicating that true sorption equilibrium was not achieved within the first 21 days. For the desorption experiments, aliquots of the sorption suspensions were placed in a flow cell, and Pu-free solutions were then pumped through the cell for a period of 12 days. Changes in influent solution flow rate were used to investigate the kinetics of Pu desorption and demonstrated that it was rate-limited over the experimental timescales. At the end of the 12-day flow cell experiments, the extent of desorption was again pH dependent, with pH 8 > pH 6 > pH 4. Further, at pH 8, less Pu was desorbed after an adsorption contact time of 6 months than after a contact time of 21 days, consistent with an aging of Pu on the clay surface. A conceptual model for Pu adsorption/desorption that incorporated known surface-mediated Pu redox reactions was used to fit the experimental data. The resulting rate constants indicated processes occurring on timescales of months and even years which may, in part, explain observations of clay colloid-facilitated Pu transport on decadal timescales. Importantly, however, our results also imply that migration of Pu adsorbed to montmorillonite colloids at long (50-100 year) timescales under oxic conditions may not be possible without considering additional phenomena, such as co-precipitation.

  12. Desorption of plutonium from montmorillonite: An experimental and modeling study

    DOE PAGES

    Begg, James D.; Zavarin, Mavrik; Kersting, Annie B.

    2017-01-15

    Desorption of plutonium (Pu) will likely control the extent to which it is transported by mineral colloids. In this article, we evaluated the adsorption/desorption behavior of Pu on SWy-1 montmorillonite colloids at pH 4, pH 6, and pH 8 using batch adsorption and flow cell desorption experiments. After 21 days adsorption, Pu(IV) affinity for montmorillonite displayed a pH dependency, with Kd values highest at pH 4 and lowest at pH 8. The pH 8 experiment was further allowed to equilibrate for 6 months and showed an increase in Kd, indicating that true sorption equilibrium was not achieved within the firstmore » 21 days. For the desorption experiments, aliquots of the sorption suspensions were placed in a flow cell, and Pu-free solutions were then pumped through the cell for a period of 12 days. Changes in influent solution flow rate were used to investigate the kinetics of Pu desorption and demonstrated that it was rate-limited over the experimental timescales. At the end of the 12-day flow cell experiments, the extent of desorption was again pH dependent, with pH 8 > pH 6 > pH 4. Further, at pH 8, less Pu was desorbed after an adsorption contact time of 6 months than after a contact time of 21 days, consistent with an aging of Pu on the clay surface. In addition, a conceptual model for Pu adsorption/desorption that incorporated known surface-mediated Pu redox reactions was used to fit the experimental data. The resulting rate constants indicated processes occurring on timescales of months and even years which may, in part, explain observations of clay colloid-facilitated Pu transport on decadal timescales. Importantly, however, our results also imply that migration of Pu adsorbed to montmorillonite colloids at long (50–100 year) timescales under oxic conditions may not be possible without considering additional phenomena, such as co-precipitation.« less

  13. Experimental modelling of flow - bed interactions in Jökulhlaups

    NASA Astrophysics Data System (ADS)

    Carrivick, J. L.; Xie, Z.; Sleigh, A.; Hubbard, M.

    2009-04-01

    Jökulhlaups (glacial outburst floods) are a sudden release and advancing wave of water and sediment from a glacier, with a peak discharge that is often several orders of magnitude greater than perennial flows. Jökulhlaup hazards are regularly incorporated into risk assessments for glaciated areas because the associated flood hazards are numerous. Jökulhlaup hazards are primarily due to direct impacts, caused by a frontal surge wave, from debris within a flow body, and from the mass and consistency of the flows. A number of secondary impacts also pose hazards, including widespread deposition of sediment and blocked tributary streams. It is rapid landscape change, which is achieved the mobilization and redistribution of sediment that causes one of the greatest hazards due to jökulhlaups. However, direct measurement of such phenomena is virtually impossible. The aim of this project is therefore to parameterise hydrodynamic - sedimentary interactions in experimental jökulhlaups. Specifically, this project applies laboratory flume modelling, which offers a hitherto untapped opportunity for examining complex interactions between water and sediment within outburst floods. The experimental set-up is of a tradition lock-gate design with a straight 4 m long tank. Hydraulics are scaled at 1:20 froude scale and the following controls on frontal wave flow-bed interactions and hence on rapid landscape change are being investigated: 1. Pre-existing mobile sediment effects, fixed bed roughness effects, sediment concentration effects, mobile bed effects. An emphasis is being maintained on examining the downstream temporal and spatial change in physical character of the water / sediment frontal wave. Facilities are state-of-the-art with a fully-automated laser bed-profiler to measure bed elevation after a run, Seatek arrays to measure transient flow depths, 0.5 Hz Ultrasonic Velocimeter Profiling to measure within-flow velocities, and Ultrasonic High-Concentration Meter (UHCM

  14. Solar-Powered Desalination: A Modelling and Experimental Study

    NASA Astrophysics Data System (ADS)

    Leblanc, Jimmy; Andrews, John

    2007-10-01

    materials were investigated: copper-nickel and a commercially available plastic. The modelling and design of a three effects MEE system is also discussed. The effects of the important design and operating parameters (recovery ratio, thermal energy, parasitic electrical energy, distillate production and solar collection area) controlling the cost of fresh water determined both from the computer simulation and experimental results are presented and analysed in this paper. Future work in the overall research program is also outlined.

  15. System identification of finite element modeling parameters using experimental spatial dynamic modeling

    NASA Astrophysics Data System (ADS)

    Lindholm, Brian E.; West, Robert L.

    1994-09-01

    A design parameter based update methodology for updating finite models based on the results of experimental dynamics tests is presented. In the proposed method, analyst-selected design parameters are updated with the objective of making realistic changes to a finite element model that will enable the model to more accurately predict the behavior of the structure. This process of 'reconciling' the finite element model with experimental data seeks to bring uncertainty in design parameters into the formulation for realistic updates of the model parameters. The reconciliation process becomes a problem of system identification. Since the finite element model is a spatial model, the high spatial density measurement of the structure's operating shape by the scanning laser-Doppler vibrometer is highly desirable. The reconciliation process updates the selected design parameters by solving a non-linear least-squares problem in which the differences between laser-based velocity measurements and analytically derived structural velocity fields are minimized over the entire structure. In the formulation, design or model parameters with greatest uncertainty are identified first, retaining statistical qualification on the estimates. This method lends itself to cross-validation of the model over the entire structure as well as at several frequencies of interest or over a frequency range. Model order analysis can also be performed within the process to ensure that the correct model is identified. The experimental velocity field is obtained by sinusoidally exciting the test structure at a given frequency and acquiring steady-state velocity data with a scanning laser-Doppler vibrometer. Conceptually, the laser-based measurements are samples of the structure's velocity field of operating shape. The finite element formulation used to generate the analytical steady-state velocity field is derived using either a dynamic stiffness finite element formulation or a static stiffness

  16. Aerothermal modeling, phase 1. Volume 2: Experimental data

    NASA Technical Reports Server (NTRS)

    Kenworthy, M. J.; Correa, S. M.; Burrus, D. L.

    1983-01-01

    The experimental test effort is discussed. The test data are presented. The compilation is divided into sets representing each of the 18 experimental configurations tested. A detailed description of each configuration, and plots of the temperature difference ratio parameter or pattern factor parameter calculated from the test data are also provided.

  17. Experimental verification of physical model of pulsed laser welding

    SciTech Connect

    Jellison, J.L.; Keicher, D.M.

    1990-01-01

    Whereas most experimental and theoretical studies of the role of convection in fusion welding have been concerned with continuous heat sources, a pulsed heat source is the focus of this study. This is primarily an experimental study of the pulsed Nd:YAG laser welding of austenitic stainless steels. 12 refs., 9 figs.

  18. Principles of model building: an experimentation-aided approach to development of models for signaling networks.

    PubMed

    Ganesan, Ambhighainath; Levchenko, Andre

    2012-01-01

    Living cells continuously probe their environment and respond to a multitude of external cues. The information about the environment is carried by signaling cascades that act as "internal transducing and computing modules," coupled into complex and interconnected networks. A comprehensive understanding of how cells make decisions therefore necessitates a sound theoretical framework, which can be achieved through mathematical modeling of the signaling networks. In this chapter, we conceptually describe the typical workflow involved in building mathematical models that are motivated by and are developed in a tight integration with experimental analysis. In particular, we delineate the steps involved in a generic, iterative experimentation-driven model-building process, both through informal discussion and using a recently published study as an example. Experiments guide the initial development of mathematical models, including choice of appropriate template model and parameter revision. The model can then be used to generate and test hypotheses quickly and inexpensively, aiding in judicious design of future experiments. These experiments, in turn, are used to update the model. The model developed at the end of this exercise not only predicts functional behavior of the system under study but also provides insight into the biophysical underpinnings of signaling networks.

  19. Design, experimentation, and modeling of a novel continuous biodrying process

    NASA Astrophysics Data System (ADS)

    Navaee-Ardeh, Shahram

    biodrying reactor were the type of biomass feed and the outlet relative humidity profiles. The biomass feed is mill specific and since one mill was studied for this study, the nutrition level of the biomass feed was found adequate for the microbial activity, and hence the type of biomass is a fixed parameter. The influence of outlet relative humidity profile was investigated on the overall performance and the complexity index of the continuous biodrying reactor. The best biodrying efficiency was achieved at an outlet relative humidity profile which controls the removal of unbound water at the wet-bulb temperature in the 1st and 2nd compartments of the reactor, and the removal of bound water at the dry-bulb temperature in the 3rd and 4th compartments. Through a systematic modeling approach, a 2-D model was developed to describe the transport phenomena in the continuous biodrying reactor. The results of the 2-D model were in satisfactory agreement with the experimental data. It was found that about 30% w/w of the total water removal (drying rate) takes place in the 1st and 2nd compartments mainly under a convection dominated mechanism, whereas about 70% w/w of the total water removal takes place in the 3rd and 4th compartments where a bioheat-diffusion dominated mechanism controls the transport phenomena. The 2-D model was found to be an appropriate tool for the estimation of the total water removal rate (drying rate) in the continuous biodrying reactor when compared to the 1-D model. A dimensionless analysis was performed on the 2-D model and established the preliminary criteria for the scale-up of the continuous biodrying process. Finally, a techno-economic assessment of the continuous biodrying process revealed that there is great potential for the implementation of the biodrying process in Canadian pulp and paper mills. The techno-economic results were compared to the other competitive existing drying technologies. It was proven that the continuous biodrying process

  20. Effects of Montelukast in an Experimental Model of Acute Pancreatitis

    PubMed Central

    Angı, Serkan; Eken, Hüseyin; Kılıç, Erol; Karaköse, Oktay; Balci, Gürhan; Somuncu, Erkan

    2016-01-01

    Background We evaluated the hematological, biochemical, and histopathological effects of Montelukast on pancreatic damage in an experimental acute pancreatitis model created by cerulein in rats before and after the induction of pancreatitis. Materials/Methods Forty rats were divided into 4 groups with 10 rats each. The study groups were: the Cerulein (C) group, the Cerulein + early Montelukast (CMe) group, the Cerulein + late Montelukast (CMl) group, and the Control group. The pH, pO2, pCO2, HCO3, leukocyte, hematocrit, pancreatic amylase, and lipase values were measured in the arterial blood samples taken immediately before rats were killed. Results There were statistically significant differences between the C group and the Control group in the values of pancreatic amylase, lipase, blood leukocyte, hematocrit, pH, pO2, pCO2, HCO3, and pancreatic water content, and also in each of the values of edema, inflammation, vacuolization, necrosis, and total histopathological score (P<0.05). When the CMl group and C group were compared, no statistically significant differences were found in any parameter analyzed. When the CMe group was compared with the C group, pancreatic amylase, lipase, pH, PO2, pCO2, HCO3, pancreatic water content, histopathological edema, inflammation, and total histopathological score values were significantly different between the groups (P<0.05). Finally, when the CMe group and the Control group were compared, significant differences were found in all except 2 (leukocyte and pO2) parameters (P<0.05). Conclusions Leukotriene receptor antagonists used in the late phases of pancreatitis might not result in any benefit; however, when they are given in the early phases or prophylactically, they may decrease pancreatic damage. PMID:27479458

  1. Subsurface Immobilization of Plutonium: Experimental and Model Validation Studies

    SciTech Connect

    Rittmann, Bruce E; Deo, Randhir P; Reed, Donald T

    2008-08-13

    We conducted a coordinated experimental and modeling study centered on the interaction of Shewanella alga BrY (S. alga) with plutonium species and phases. Plutonium is the key contaminant of concern at several DOE sites that are being addressed by the overall ERSP program. The over-arching goal of this research was to understand the long-term stability of bio-precipitated immobilized plutonium phases under changing redox conditions in biologically active systems. To initiate the process of plutonium immobilization, a side-by-side comparison of the bioreduction of uranyl and plutonyl species was conducted with S. alga. Uranyl was reduced in our system, consistent with literature reports, but we noted coupling between abiotic and biotic processes and observed that non-reductive pathways to precipitation typically exist. Additionally, a key role of biogenic Fe2+, which is known to reduce uranyl at low pH, is suggested. In contrast, residual organics, present in biologically active systems, reduce Pu(VI) species to Pu(V) species at near-neutral pH. The predominance of relatively weak complexes of PuO2+ is an important difference in how the uranyl and plutonyl species interacted with S. alga. Pu(V) also led to increased toxicity towards S. alga and is also more easily reduced by microbial activity. Biogenic Fe2+, produced by S. alga when Fe3+ is present as an electron acceptor, also played a key role in understanding redox controls and pathways in this system. Overall, the bioreduction of plutonyl was observed under anaerobic conditions, which favor its immobilization in the subsurface. Understanding the mechanism by which redox control is established in biologically active systems is a key aspect of remediation and immobilization strategies for actinides when they are present as subsurface contaminants.

  2. Proconvulsant potential of cyproheptadine in experimental animal models.

    PubMed

    Singh, Damanpreet; Goel, Rajesh Kumar

    2010-08-01

    In epileptic patients cyproheptadine is frequently prescribed as an appetite stimulant for the treatment of anorexia associated with anti-epileptic drugs and for the management of 'serotonin syndrome' in depressed epileptic patients. However, the study of serotonergic and histaminergic pathway shows that the decreased neurotransmission of serotonin and histamine in the brain reduces seizures threshold. Since, cyproheptadine interferes with these pathways via antagonizing subtypes of 5-HT(1/2) receptors and H(1) receptor, therefore the present study was undertaken to investigate its effect on seizures threshold, so as to substantiate its use in epileptics. In the present study convulsions were induced in mice by, maximum electroshock (MES), picrotoxin, and pentylenetetrazol (PTZ). Cyproheptadine (4 mg/kg, i.p.) was administered per se and along with clinically used anti-epileptic drugs (phenytoin 25 mg/kg, i.p. and diazepam 5 mg/kg, i.p.) in different groups of mice, onset and extent of convulsions in these groups were compared with that of vehicle control and anti-epileptics per se treated groups. Percentage mortality in all groups was also determined. Results depicted a significant increase in duration of tonic hind limb extension in MES and decrease in latency to clonic convulsions induced by PTZ and picrotoxin in cyproheptadine treated groups (per se and along with anti-epileptics), as compared to vehicle control and anti-epileptics per se treated groups respectively. Percentage mortality was also increased with cyproheptadine treatment. Therefore it is concluded that cyproheptadine pretreatment reduces threshold, increases severity of seizures and decreases the efficacy of clinically used anti-epileptic drugs in experimental animal models of convulsions.

  3. Zebrafish as a novel experimental model for developmental toxicology.

    PubMed

    Teraoka, Hiroki; Dong, Wu; Hiraga, Takeo

    2003-06-01

    It is widely believed that embryos and infants during development are highly sensitive to chemicals that cause serious damage to growth. However, knowledge on the mechanisms of developmental toxicity is scarce. One reason for this is limited convenient model system other than organ cultures using rodents to study the various aspects of developmental toxicology. Cultured cells are not always adequate for this purpose, since events in morphogenesis are processed through interactions with other tissues. We focused on zebrafish embryo (Danio rerio), one of the most important organisms in developmental biology. Saturation mutagenesis, applied to drosophila and nematode to define the functions of genes, has been carried out in zebrafish but almost no other vertebrate, and several thousand lines are available due to the rapid growth and transparent body of this embryo. Enhanced databases for the genome and ESTs are available at websites with abundant genetic and biological background. By targeted gene knock-down with morpholino-modified antisense oligonucleotieds (morpholinos), the translation of a specific protein can be transiently blocked for several days. Many reporter systems in vivo have been established mainly as GFP-transgenic fish for environmental chemicals. Although several excellent studies have been performed with zebrafish embryos on the effects of chemicals, the developmental toxicology of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been most extensively studied to date. We have found that TCDD induces apoptosis in dorsal midbrain with a concomitant decrease in local blood flow, using developing zebrafish. TCDD seems to produce oxidative stress through CYP1A induction in vascular endothelium, resulting in local circulation failure and apoptosis in the dorsal midbrain. In addition to applications in toxicology, an experimental system with zebrafish embryos could help to clarify the mechanism of congenital anomaly, which arises from genetic mutation.

  4. Towards Predictive Computational Models of Oncolytic Virus Therapy: Basis for Experimental Validation and Model Selection

    PubMed Central

    Wodarz, Dominik; Komarova, Natalia

    2009-01-01

    Oncolytic viruses are viruses that specifically infect cancer cells and kill them, while leaving healthy cells largely intact. Their ability to spread through the tumor makes them an attractive therapy approach. While promising results have been observed in clinical trials, solid success remains elusive since we lack understanding of the basic principles that govern the dynamical interactions between the virus and the cancer. In this respect, computational models can help experimental research at optimizing treatment regimes. Although preliminary mathematical work has been performed, this suffers from the fact that individual models are largely arbitrary and based on biologically uncertain assumptions. Here, we present a general framework to study the dynamics of oncolytic viruses that is independent of uncertain and arbitrary mathematical formulations. We find two categories of dynamics, depending on the assumptions about spatial constraints that govern that spread of the virus from cell to cell. If infected cells are mixed among uninfected cells, there exists a viral replication rate threshold beyond which tumor control is the only outcome. On the other hand, if infected cells are clustered together (e.g. in a solid tumor), then we observe more complicated dynamics in which the outcome of therapy might go either way, depending on the initial number of cells and viruses. We fit our models to previously published experimental data and discuss aspects of model validation, selection, and experimental design. This framework can be used as a basis for model selection and validation in the context of future, more detailed experimental studies. It can further serve as the basis for future, more complex models that take into account other clinically relevant factors such as immune responses. PMID:19180240

  5. COMPUTATIONAL AND EXPERIMENTAL MODELING OF SLURRY BUBBLE COLUMN REACTORS

    SciTech Connect

    Paul C.K. Lam; Isaac K. Gamwo; Dimitri Gidaspow

    2002-05-01

    The objective of this study was to develop a predictive experimentally verified computational fluid dynamics (CFD) model for gas-liquid-solid flow. A three dimensional transient computer code for the coupled Navier-Stokes equations for each phase was developed and is appended in this report. The principal input into the model is the viscosity of the particulate phase which was determined from a measurement of the random kinetic energy of the 800 micron glass beads and a Brookfield viscometer. The details are presented in the attached paper titled ''CFD Simulation of Flow and Turbulence in a Slurry Bubble Column''. This phase of the work is in press in a referred journal (AIChE Journal, 2002) and was presented at the Fourth International Conference on Multiphase Flow (ICMF 2001) in New Orleans, May 27-June 1, 2001 (Paper No. 909). The computed time averaged particle velocities and concentrations agree with Particle Image Velocimetry (PIV) measurements of velocities and concentrations, obtained using a combination of gamma-ray and X-ray densitometers, in a slurry bubble column, operated in the bubbly-coalesced fluidization regime with continuous flow of water. Both the experiment and the simulation show a down-flow of particles in the center of the column and up-flow near the walls and nearly uniform particle concentration. Normal and shear Reynolds stresses were constructed from the computed instantaneous particle velocities. The PIV measurement and the simulation produced instantaneous particle velocities. The PIV measurement and the simulation produced similar nearly flat horizontal profiles of turbulent kinetic energy of particles. To better understand turbulence we studied fluidization in a liquid-solid bed. This work was also presented at the Fourth International Conference on Multiphase Flow (ICMF 2001, Paper No. 910). To understand turbulence in risers, measurements were done in the IIT riser with 530 micron glass beads using a PIV technique. This report

  6. Modeling, simulation and experimental verification of constitutive models for energetic materials

    NASA Astrophysics Data System (ADS)

    Haberman, K. S.; Bennett, J. G.; Asay, B. W.; Henson, B. F.; Funk, D. J.

    1998-07-01

    Simulation of the complete response of components and systems composed of energetic materials, such as PBX-9501 (1) is important in the determination of the safety of various explosive systems. For example, predicting the correct state of stress, rate of deformation and temperature during penetration is essential in the prediction of ignition. Such simulation requires accurate constitutive models. These models must also be computationally efficient to enable analysis of large scale three dimensional problems using explicit lagrangian finite element codes such as DYNA3D (2). However, to be of maximum utility, these predictions must be validated against robust dynamic experiments. In this paper, we report comparisons between experimental and predicted displacement fields in PBX-9501 during dynamic deformation, and describe the modeling approach. The predictions used Visco-SCRAM and the Generalized Method of Cells which have been implemented into DYNA3D. The experimental data were obtained using laser-induced fluorescence speckle photography. Results from this study have lead to more accurate models and have also guided further experimental work.

  7. Modeling, simulation and experimental verification of constitutive models for energetic materials

    SciTech Connect

    Haberman, K.S.; Bennett, J.G.; Assay, B.W.

    1997-09-01

    Simulation of the complete response of components and systems composed of energetic materials, such as PBX-9501 is important in the determination of the safety of various explosive systems. For example, predicting the correct state of stress, rate of deformation and temperature during penetration is essential in the prediction of ignition. Such simulation requires accurate constitutive models. These models must also be computationally efficient to enable analysis of large scale three dimensional problems using explicit lagrangian finite element codes such as DYNA3D. However, to be of maximum utility, these predictions must be validated against robust dynamic experiments. In this paper, the authors report comparisons between experimental and predicted displacement fields in PBX-9501 during dynamic deformation, and describe the modeling approach. The predictions used Visco-SCRAM and the Generalized Method of Cells which have been implemented into DYNA3D. The experimental data were obtained using laser-induced fluorescence speckle photography. Results from this study have lead to more accurate models and have also guided further experimental work.

  8. HF COMMUNICATION EFFECTS: EXPERIMENTAL JUSTIFICATION OF THE GAUSSIAN CHANNEL MODEL.

    DTIC Science & Technology

    correlation coefficient . An estimate of the relationship between the correlation coefficient and channel frequency spread is derived and compared with experimental data. Agreement between correlation - coefficient estimates from log-envelope change and phase change is discussed. The experimental envelope distributions of the received signal are compared with the Rayleigh, Rician, and log-normal distributions, and deviations are discussed. Alternative envelope distributions based on a conditional Rayleigh distribution are also

  9. Experimental-based modeling of a support structure as part of a full system model

    SciTech Connect

    CARNE,THOMAS G.; DOHRMANN,CLARK R.

    2000-02-29

    Structural dynamic systems are often attached to a support structure to simulate proper boundary conditions during testing. In some cases the support structure is fairly simple and can be modeled by discrete springs and dampers. In other cases the desired test conditions necessitate the use of a support structural that introduces dynamics of its own. For such cases a more complex structural dynamic model is required to simulate the response of the full combined system. In this paper experimental frequency response functions, admittance function modeling concepts, and least squares reductions are used to develop a support structure model including both translational and rotational degrees of freedom at an attachment location. Subsequently, the modes of the support structure are estimated, and a NASTRAN model is created for attachment to the tested system.

  10. Arsenic Toxicology: Translating between Experimental Models and Human Pathology

    PubMed Central

    Barchowsky, Aaron; Cartwright, Iain L.; Reichard, John F.; Futscher, Bernard W.; Lantz, R. Clark

    2011-01-01

    Background: Chronic arsenic exposure is a worldwide health problem. How arsenic exposure promotes a variety of diseases is poorly understood, and specific relationships between experimental and human exposures are not established. We propose phenotypic anchoring as a means to unify experimental observations and disease outcomes. Objectives: We examined the use of phenotypic anchors to translate experimental data to human pathology and investigated research needs for which phenotypic anchors need to be developed. Methods: During a workshop, we discussed experimental systems investigating arsenic dose/exposure and phenotypic expression relationships and human disease responses to chronic arsenic exposure and identified knowledge gaps. In a literature review, we identified areas where data exist to support phenotypic anchoring of experimental results to pathologies from specific human exposures. Discussion: Disease outcome is likely dependent on cell-type–specific responses and interaction with individual genetics, other toxicants, and infectious agents. Potential phenotypic anchors include target tissue dosimetry, gene expression and epigenetic profiles, and tissue biomarkers. Conclusions: Translation to human populations requires more extensive profiling of human samples along with high-quality dosimetry. Anchoring results by gene expression and epigenetic profiling has great promise for data unification. Genetic predisposition of individuals affects disease outcome. Interactions with infectious agents, particularly viruses, may explain some species-specific differences between human pathologies and experimental animal pathologies. Invertebrate systems amenable to genetic manipulation offer potential for elaborating impacts of specific biochemical pathways. Anchoring experimental results to specific human exposures will accelerate understanding 
of mechanisms of arsenic-induced human disease. PMID:21684831

  11. Missing experimental challenges to the Standard Model of particle physics

    NASA Astrophysics Data System (ADS)

    Perovic, Slobodan

    The success of particle detection in high energy physics colliders critically depends on the criteria for selecting a small number of interactions from an overwhelming number that occur in the detector. It also depends on the selection of the exact data to be analyzed and the techniques of analysis. The introduction of automation into the detection process has traded the direct involvement of the physicist at each stage of selection and analysis for the efficient handling of vast amounts of data. This tradeoff, in combination with the organizational changes in laboratories of increasing size and complexity, has resulted in automated and semi-automated systems of detection. Various aspects of the semi-automated regime were greatly diminished in more generic automated systems, but turned out to be essential to a number of surprising discoveries of anomalous processes that led to theoretical breakthroughs, notably the establishment of the Standard Model of particle physics. The automated systems are much more efficient in confirming specific hypothesis in narrow energy domains than in performing broad exploratory searches. Thus, in the main, detection processes relying excessively on automation are more likely to miss potential anomalies and impede potential theoretical advances. I suggest that putting substantially more effort into the study of electron-positron colliders and increasing its funding could minimize the likelihood of missing potential anomalies, because detection in such an environment can be handled by the semi-automated regime-unlike detection in hadron colliders. Despite virtually unavoidable excessive reliance on automated detection in hadron colliders, their development has been deemed a priority because they can operate at currently highest energy levels. I suggest, however, that a focus on collisions at the highest achievable energy levels diverts funds from searches for potential anomalies overlooked due to tradeoffs at the previous energy

  12. COMPUTATIONAL AND EXPERIMENTAL MODELING OF SLURRY BUBBLE COLUMN REACTORS

    SciTech Connect

    Paul Lam; Dimitri Gidaspow

    2001-08-01

    This project is a collaborative effort between the University of Akron, Illinois Institute of Technology and two industries: UOP and Energy International. The tasks involve the development of transient two and three dimensional computer codes for slurry bubble column reactors, optimization, comparison to data, and measurement of input parameters, such as the viscosity and restitution coefficients. To understand turbulence, measurements were done in the riser with 530 micron glass beads using a PIV technique. This report summarizes the measurements and simulations completed as described in details in the attached paper, ''Computational and Experimental Modeling of Three-Phase Slurry-Bubble Column Reactor.'' The Particle Image Velocimetry method described elsewhere (Gidaspow and Huilin, 1996) was used to measure the axial and tangential velocities of the particles. This method was modified with the use of a rotating colored transparent disk. The velocity distributions obtained with this method shows that the distribution is close to Maxwellian. From the velocity measurements the normal and the shear stresses were computed. Also with the use of the CCD camera a technique was developed to measure the solids volume fraction. The granular temperature profile follows the solids volume fraction profile. As predicted by theory, the granular temperature is highest at the center of the tube. The normal stress in the direction of the flow is approximately 10 times larger than that in the tangential direction. The <{nu}{prime}{sub z}{nu}{prime}{sub z}> is lower at the center where the <{nu}{prime}{sub {theta}}{nu}{prime}{sub {theta}}> is higher at that point. The Reynolds shear stress was small, producing a restitution coefficient near unity. The normal Reynolds stress in the direction of flow is large due to the fact that it is produced by the large gradient of velocity in the direction of flow compared to the small gradient in the {theta} and r directions. The kinetic theory

  13. Isospora suis: an experimental model for mammalian intestinal coccidiosis.

    PubMed

    Mundt, H-C; Joachim, A; Becka, M; Daugschies, A

    2006-01-01

    Piglets experimentally infected with 10,000 oocysts of Isospora suis in three identical trials (n = 50) were examined clinically and coproscopically from 5 to 11 days post-infection (d.p.i.), weighed in weekly intervals until the fourth week of life and compared to age-matched asymptomatic controls (n = 17). Furthermore, 17 infected piglets were histologically examined on days 5-14 p.i. Infected animals had a significantly lower weight gain than the controls and showed diarrhoea throughout, with maximum prevalence and intensity on 6 d.p.i. Half of the animals had diarrhoea for only 2 days or less. The number of diarrhoea days was negatively correlated with weight gain. Oocyst excretion started on 5 d.p.i. with peak prevalences and declined afterwards; a smaller peak was seen on 10 d.p.i. All animals excreted parasites at least once, and most of them excreted for 5-7 days. Oocyst excretion intensity paralleled the prevalence and ranged from 220 to 251,501 oocysts per gram of faeces (opg). Most samples contained 4 x 10(3) to 4 x 10(4) opg. The opg values were negatively correlated with faecal scores (samples with diarrhoea contained less oocysts) of the same day and the previous day. Histologically, necrosis followed by atrophy of the villi was most pronounced in the early stage of infection throughout the jejunum and ileum but declined thereafter. On 14 d.p.i., villous atrophy was still noticeable in the jejunum. Histology is difficult to quantify and requires large animal numbers, although the effects are visible for some time. Weight gain and faecal score can be affected by other factors than parasite infection. From the compiled data, we conclude that the established model is suitable to study piglet isosporosis with oocyst excretion being the most reliable parameter, although individual variations are considerable. A negative correlation between excretion and diarrhoea may be responsible for the difficulties in the detection of the parasite in field samples.

  14. Colloids and Radionuclide Transport: A Field, Experimental and Modeling Effort

    NASA Astrophysics Data System (ADS)

    Zhao, P.; Zavarin, M.; Sylwester, E. E.; Allen, P. G.; Williams, R. W.; Kersting, A. B.

    2002-05-01

    Natural inorganic colloids (< 1 micron particles) found in groundwater can sorb low-solubility actinides and may provide a pathway for transport through geological aquifers. The importance of colloid-facilitated transport to the transport of low-solubility actinides, such as Pu, is still not well understood. In an effort to better understand the dominant geochemical mechanisms that control Pu transport, we have performed a series of sorption/desorption experiments using mineral colloids. We focused on natural colloidal minerals present in water samples collected from both saturated and vadose zone waters at the Nevada Test Site. These minerals include zeolites, clays, silica, Mn-oxides, Fe-oxides, and calcite. X-ray absorption fine-structure spectroscopy ( both XANES and EXAFS) was performed in order to characterize the speciation of sorbed plutonium. The XANES spectra show that only Pu(IV) was detected (within experimental error) on these mineral surfaces when the starting Pu oxidation state was +5, indicating that Pu(V) was reduced to Pu(IV) during sorption. The EXAFS detected Pu-M and Pu-C interactions (where M=Fe, Mn, or Si) indicating Pu(IV) surface complexation along with carbonate ternary complex formation on most of the minerals tested. Although the plutonium sorption as Pu(IV) species is mineral independent, the actual sorption paths are different for different minerals. The sorption rates were compared to the rates of plutonium disproportionation under similar conditions. The batch sorption/desorption experiments of Pu(IV) and Pu(V) onto colloidal zeolite (clinoptilolite, colloids particle size 171 ñ 25 nm) were conducted in synthetic groundwater (similar to J-13, Yucca Mountain standard) with a pH range from 4 to 10 and initial plutonium concentration of 10-9 M. The results show that Pu(IV) sorption takes place within an hour, while the rates of Pu(V) sorption onto the colloids is much slower and mineral dependent. The kinetic results from the batch

  15. An Experimental Approach to Mathematical Modeling in Biology

    ERIC Educational Resources Information Center

    Ledder, Glenn

    2008-01-01

    The simplest age-structured population models update a population vector via multiplication by a matrix. These linear models offer an opportunity to introduce mathematical modeling to students of limited mathematical sophistication and background. We begin with a detailed discussion of mathematical modeling, particularly in a biological context.…

  16. Model-free forecasting outperforms the correct mechanistic model for simulated and experimental data

    PubMed Central

    Perretti, Charles T.; Munch, Stephan B.; Sugihara, George

    2013-01-01

    Accurate predictions of species abundance remain one of the most vexing challenges in ecology. This observation is perhaps unsurprising, because population dynamics are often strongly forced and highly nonlinear. Recently, however, numerous statistical techniques have been proposed for fitting highly parameterized mechanistic models to complex time series, potentially providing the machinery necessary for generating useful predictions. Alternatively, there is a wide variety of comparatively simple model-free forecasting methods that could be used to predict abundance. Here we pose a rather conservative challenge and ask whether a correctly specified mechanistic model, fit with commonly used statistical techniques, can provide better forecasts than simple model-free methods for ecological systems with noisy nonlinear dynamics. Using four different control models and seven experimental time series of flour beetles, we found that Markov chain Monte Carlo procedures for fitting mechanistic models often converged on best-fit parameterizations far different from the known parameters. As a result, the correctly specified models provided inaccurate forecasts and incorrect inferences. In contrast, a model-free method based on state-space reconstruction gave the most accurate short-term forecasts, even while using only a single time series from the multivariate system. Considering the recent push for ecosystem-based management and the increasing call for ecological predictions, our results suggest that a flexible model-free approach may be the most promising way forward. PMID:23440207

  17. Bayesian latent variable models for the analysis of experimental psychology data.

    PubMed

    Merkle, Edgar C; Wang, Ting

    2016-03-18

    In this paper, we address the use of Bayesian factor analysis and structural equation models to draw inferences from experimental psychology data. While such application is non-standard, the models are generally useful for the unified analysis of multivariate data that stem from, e.g., subjects' responses to multiple experimental stimuli. We first review the models and the parameter identification issues inherent in the models. We then provide details on model estimation via JAGS and on Bayes factor estimation. Finally, we use the models to re-analyze experimental data on risky choice, comparing the approach to simpler, alternative methods.

  18. Model-Based Optimal Experimental Design for Complex Physical Systems

    DTIC Science & Technology

    2015-12-03

    NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) Jean-Luc Cambier Program Officer, Computational Mathematics , AFOSR/RTA 875 N...computational tools have been inadequate. Our goal has been to develop new mathematical formulations, estimation approaches, and approximation strategies...previous suboptimal approaches. 15. SUBJECT TERMS computational mathematics ; optimal experimental design; uncertainty quantification; Bayesian inference

  19. A green infrastructure experimental site for developing and evaluating models

    EPA Science Inventory

    The Ecosystems Research Division (ERD) of the U.S. EPA’s National Exposure Research Laboratory (NERL) in Athens, GA has a 14-acre urban watershed which has become an experimental research site for green infrastructure studies. About half of the watershed is covered by pervious la...

  20. A green infrastructure experimental site for developing and evaluating models

    EPA Science Inventory

    The Ecosystems Research Division (ERD) of the U.S. EPA’s National Exposure Research Laboratory (NERL) in Athens, GA has a 14-acre urban watershed which has become an experimental research site for green infrastructure studies. About half of the watershed is covered by pervious la...

  1. Cosmic-Ray Spectrum Approximation Model: Experimental Results and Comparison with Other Models

    NASA Astrophysics Data System (ADS)

    Buchvarova, M.; Draganov, D.

    2013-06-01

    We discuss a model which parameterizes the cosmic-ray (CR) spectrum at different physical conditions, which include the most important effects controlling the CR intensity, like convection-diffusion and energy losses. By a suitable choice of parameters the proposed model results in two approximations: one close to a "force-field" model (describing the energy losses of CRs in the inner heliosphere) and a "convection-diffusion" equation (giving the reduction of CR intensity in the outer heliosphere). The BESS ( Balloon-borne Experiment with Superconducting Spectrometer) experimental spectra of galactic protons and helium nuclei are fitted by the model spectra. The calculation of the unknown parameters is performed using a constrained least squares method as an alternative to the standard chi-square minimization method, because the data contain not only random errors, but also systematic ones. The CR spectrum approximation (CRSA) model is compared to the Moscow State University (MSU) model and the Badhwar and O'Neill (Badhwar and O'Neill, Adv. Space. Res. 14, 749, 1994; Adv. Space Res. 17, 7, 1994) model; we show that depending on the choice of the model parameters it can be examined in the context of one of these two models. We derive a relation between the parameters of the CRSA and MSU models for rigidities above about 10 GV (drift effects are ignored) during periods of low to approximately average levels of solar activity. The drawbacks of the proposed approximation are that: i) the model parameters do not depend on rigidity and ii) the model does not take into account general trends in the variations of the heliospheric magnetic field; thus, the influence of the drift effects on the shape of the spectral curves for different magnetic field polarity swings is ignored.

  2. Maneuver simulation model of an experimental hovercraft for the Antarctic

    NASA Astrophysics Data System (ADS)

    Murao, Rinichi

    Results of an investigation of a hovercraft model designed for Antarctic conditions are presented. The buoyancy characteristics, the propellant control system, and simulation model control are examined. An ACV (air cushion vehicle) model of the hovercraft is used to examine the flexibility and friction of the skirt. Simulation results are presented which show the performance of the hovercraft.

  3. Fractional differential equations based modeling of microbial survival and growth curves: model development and experimental validation.

    PubMed

    Kaur, A; Takhar, P S; Smith, D M; Mann, J E; Brashears, M M

    2008-10-01

    A fractional differential equations (FDEs)-based theory involving 1- and 2-term equations was developed to predict the nonlinear survival and growth curves of foodborne pathogens. It is interesting to note that the solution of 1-term FDE leads to the Weibull model. Nonlinear regression (Gauss-Newton method) was performed to calculate the parameters of the 1-term and 2-term FDEs. The experimental inactivation data of Salmonella cocktail in ground turkey breast, ground turkey thigh, and pork shoulder; and cocktail of Salmonella, E. coli, and Listeria monocytogenes in ground beef exposed at isothermal cooking conditions of 50 to 66 degrees C were used for validation. To evaluate the performance of 2-term FDE in predicting the growth curves-growth of Salmonella typhimurium, Salmonella Enteritidis, and background flora in ground pork and boneless pork chops; and E. coli O157:H7 in ground beef in the temperature range of 22.2 to 4.4 degrees C were chosen. A program was written in Matlab to predict the model parameters and survival and growth curves. Two-term FDE was more successful in describing the complex shapes of microbial survival and growth curves as compared to the linear and Weibull models. Predicted curves of 2-term FDE had higher magnitudes of R(2) (0.89 to 0.99) and lower magnitudes of root mean square error (0.0182 to 0.5461) for all experimental cases in comparison to the linear and Weibull models. This model was capable of predicting the tails in survival curves, which was not possible using Weibull and linear models. The developed model can be used for other foodborne pathogens in a variety of food products to study the destruction and growth behavior.

  4. [RESEARCH PROGRESS OF EXPERIMENTAL ANIMAL MODELS OF AVASCULAR NECROSIS OF FEMORAL HEAD].

    PubMed

    Yu, Kaifu; Tan, Hongbo; Xu, Yongqing

    2015-12-01

    To summarize the current researches and progress on experimental animal models of avascular necrosis of the femoral head. Domestic and internation literature concerning experimental animal models of avascular necrosis of the femoral head was reviewed and analyzed. The methods to prepare the experimental animal models of avascular necrosis of the femoral head can be mainly concluded as traumatic methods (including surgical, physical, and chemical insult), and non-traumatic methods (including steroid, lipopolysaccharide, steroid combined with lipopolysaccharide, steroid combined with horse serum, etc). Each method has both merits and demerits, yet no ideal methods have been developed. There are many methods to prepare the experimental animal models of avascular necrosis of the femoral head, but proper model should be selected based on the aim of research. The establishment of ideal experimental animal models needs further research in future.

  5. Theoretical and experimental modeling of a rail gun accelerator

    NASA Astrophysics Data System (ADS)

    Zheleznyj, V. B.; Zagorskij, A. V.; Katsnel'Son, S. S.; Kudryavtsev, A. V.; Plekhanov, A. V.

    1993-04-01

    Results of a series of experiments in the acceleration of macrobodies are analyzed using an integral model of a current arc and a quasi-1D magnetic gasdynamic model. The integral model uses gasdynamic equations averaged by the size of a plasma pump and equations based on the second Kirchhoff's law for electrical current. The quasi-1D model is based on 1D magnetic gasdynamic equations for mean values of density, pressure, velocity, and internal power. Electromagnetic parameters are determined from Maxwell integral equations. It is concluded that the proposed models take into account the major mechanisms of momentum loss and are capable of adequately describing electromagnetic rail accelerators.

  6. Inter-comparison of experimental catchment data and hydrological modelling

    NASA Astrophysics Data System (ADS)

    Singh, Shailesh Kumar; Ibbitt, Richard; Srinivasan, M. S.; Shankar, Ude

    2017-07-01

    Hydrological models account for the storage, flow of water and water balance in a catchment, including exchanges of water and energy with the ground, atmosphere and oceans. Because of the need to simplify hydrological models, parameters are often included to help with modelling hydrological processes. Generally the parameters of lumped, semi or distributed hydrological models depend on the values estimated at a gauged location, generally at outlet of the catchment (mostly using discharge). In this approach it is hard to judge how well a model represents internal catchment processes of the hydrological cycle as well as also ignoring the spatial heterogeneity of the catchment. The purpose of the paper is to assess, and potentially improve, the ability of a physically-based semi-distributed hydrological model, TopNet, using a spatially and temporally detailed set of field measurements of catchment responses to diverse weather conditions. The TopNet rainfall-runoff model was applied to the Waipara catchment located in the South Island of New Zealand. Observations from field experiments were compared with the simulation results of uncalibrated TopNet model. The total amount of simulated runoff showed reasonable agreement with observations. However, the model overestimated baseflow and underestimated surface flow. The results show that soil moisture variation within the catchment is well represented by the model. However, comparison of the observed water balance with model results show that there is a deficiency in the calculation of evapotranspiration.

  7. Quantum Dynamics Simulations for Modeling Experimental Pump-Probe Measurements

    NASA Astrophysics Data System (ADS)

    Pearson, Brett; Nayyar, Sahil; Liss, Kyle; Weinacht, Thomas

    2016-05-01

    Time-resolved studies of quantum dynamics have benefited greatly from developments in ultrafast table-top and free electron lasers. Advances in computer software and hardware have lowered the barrier for performing calculations such that relatively simple simulations allow for direct comparison with experimental results. We describe here a set of quantum dynamics calculations in low-dimensional molecular systems. The calculations incorporate coupled electronic-nuclear dynamics, including two interactions with an applied field and nuclear wave packet propagation. The simulations were written and carried out by undergraduates as part of a senior research project, with the specific goal of allowing for detailed interpretation of experimental pump-probe data (in additional to the pedagogical value).

  8. Experimental observations and modelling of intrinsic rotation reversals in tokamaks

    NASA Astrophysics Data System (ADS)

    Camenen, Y.; Angioni, C.; Bortolon, A.; Duval, B. P.; Fable, E.; Hornsby, W. A.; McDermott, R. M.; Na, D. H.; Na, Y.-S.; Peeters, A. G.; Rice, J. E.

    2017-03-01

    The progress made in understanding spontaneous toroidal rotation reversals in tokamaks is reviewed and current ideas to solve this ten-year-old puzzle are explored. The paper includes a summarial synthesis of the experimental observations in AUG, C-Mod, KSTAR, MAST and TCV tokamaks, reasons why turbulent momentum transport is thought to be responsible for the reversals, a review of the theory of turbulent momentum transport and suggestions for future investigations.

  9. Experimental Model for the Study of Periodontal Wound Healing

    DTIC Science & Technology

    1991-05-01

    Vande Velde et al., 1989, Kon et al, 1991). Experimentally induced defects that were chronically irritated with steel matrices and plaque accumulation...Millipore filters were placed over the fenestrations and 2- 3 mm beyond their borders to prevent gingival connective tissue from contacting the root...including periodontal probing was accomplished to assure no periodontal disease, other than gingivitis , existed. The teeth were scaled to remove

  10. Finding the right balance between groundwater model complexity and experimental effort via Bayesian model selection

    NASA Astrophysics Data System (ADS)

    Schöniger, Anneli; Illman, Walter A.; Wöhling, Thomas; Nowak, Wolfgang

    2015-12-01

    Groundwater modelers face the challenge of how to assign representative parameter values to the studied aquifer. Several approaches are available to parameterize spatial heterogeneity in aquifer parameters. They differ in their conceptualization and complexity, ranging from homogeneous models to heterogeneous random fields. While it is common practice to invest more effort into data collection for models with a finer resolution of heterogeneities, there is a lack of advice which amount of data is required to justify a certain level of model complexity. In this study, we propose to use concepts related to Bayesian model selection to identify this balance. We demonstrate our approach on the characterization of a heterogeneous aquifer via hydraulic tomography in a sandbox experiment (Illman et al., 2010). We consider four increasingly complex parameterizations of hydraulic conductivity: (1) Effective homogeneous medium, (2) geology-based zonation, (3) interpolation by pilot points, and (4) geostatistical random fields. First, we investigate the shift in justified complexity with increasing amount of available data by constructing a model confusion matrix. This matrix indicates the maximum level of complexity that can be justified given a specific experimental setup. Second, we determine which parameterization is most adequate given the observed drawdown data. Third, we test how the different parameterizations perform in a validation setup. The results of our test case indicate that aquifer characterization via hydraulic tomography does not necessarily require (or justify) a geostatistical description. Instead, a zonation-based model might be a more robust choice, but only if the zonation is geologically adequate.

  11. Three-dimensional FEM model of FBGs in PANDA fibers with experimentally determined model parameters

    NASA Astrophysics Data System (ADS)

    Lindner, Markus; Hopf, Barbara; Koch, Alexander W.; Roths, Johannes

    2017-04-01

    A 3D-FEM model has been developed to improve the understanding of multi-parameter sensing with Bragg gratings in attached or embedded polarization maintaining fibers. The material properties of the fiber, especially Young's modulus and Poisson's ratio of the fiber's stress applying parts, are crucial for accurate simulations, but are usually not provided by the manufacturers. A methodology is presented to determine the unknown parameters by using experimental characterizations of the fiber and iterative FEM simulations. The resulting 3D-Model is capable of describing the change in birefringence of the free fiber when exposed to longitudinal strain. In future studies the 3D-FEM model will be employed to study the interaction of PANDA fibers with the surrounding materials in which they are embedded.

  12. New experimental model for the evaluation of adaptogenic products.

    PubMed

    Ramachandran, U; Divekar, H M; Grover, S K; Srivastava, K K

    1990-07-01

    A new animal model for evaluating improvement in physical work performance and endurance in an adverse environment is described. In this model, rats in restraint were exposed to 5 degrees C at 480 mmHg atmospheric pressure. Results were compared to an animal forced to swim in water at 23 degrees C. In both the models, colonic temperature (Tr) of the rats was continually monitored during exposure to adverse environment and during recovery at 32 degrees C and normal atmospheric pressure. The time and pattern for Tr fall to 23 degrees C and its recovery to 37 degrees C were used as measures of endurance. The cold-hypoxia-restraint model was found to provide more precise results compared with the cold-swimming model. Panax ginseng root and Ginkgo biloba leaf extracts were compared for their positive endurance-promoting properties using both models.

  13. MELCOR model for an experimental 17x17 spent fuel PWR assembly.

    SciTech Connect

    Cardoni, Jeffrey

    2010-11-01

    A MELCOR model has been developed to simulate a pressurized water reactor (PWR) 17 x 17 assembly in a spent fuel pool rack cell undergoing severe accident conditions. To the extent possible, the MELCOR model reflects the actual geometry, materials, and masses present in the experimental arrangement for the Sandia Fuel Project (SFP). The report presents an overview of the SFP experimental arrangement, the MELCOR model specifications, demonstration calculation results, and the input model listing.

  14. Puerto Rico Experimental Model Dental Auxiliary Training Program. The Comprehensive Report, Exhibits A to F.

    ERIC Educational Resources Information Center

    Puerto Rico Univ., San Juan. School of Dentistry.

    This annex supplements the Puerto Rico Experimental Model Dental Training Program Comprehensive Report (CE 028 213) and is comprised of exhibits A through F. Among the information included in the exhibits is the experimental model schedule, the schematic representation, the content display, and the course outlines for all courses in the program.…

  15. MATREX - Modeling Architecture for Technology, Research and EXperimentation

    DTIC Science & Technology

    2008-03-10

    Cross-Army Environment FCS LSI Simulation Environment (FSE) And Integrated Phase 2 (IP-2) Simulation Middleware (HLA / RTI) C3 Human Performance Model... C3 HPM) hlaControl hlaResults SQL Database Comprehensive Munitions and Sensor Simulation (CMS2) Logistics Server (LOG) NEC2 Effects Engine (NEC2...Model Y $ LVS MC2CDAS CMS2/UCModel BModel A $ AMS ARMS VDMSMSLS C3 Grid Meta-Modeling & Code Generation Concept M&S Interoperability Problem Space

  16. Precipitation of experimental autoallergic uveoretinitis by cyclosporin A withdrawal: an experimental model of uveitis relapse.

    PubMed Central

    Atkinson, E G; Dinning, W J; Kasp, E; Graham, E M; Dumonde, D C

    1989-01-01

    This study set out to determine whether withdrawal of cyclosporin A (CyA) in Lewis rats sensitized to retinal S antigen would precipitate experimental autoallergic uveoretinitis (EAU), and whether challenge of such animals with S antigen or an unrelated stimulus would accelerate EAU onset after drug withdrawal. Rats were sensitized with 50 micrograms S antigen in Freund's complete adjuvant (FCA) and EAU onset was suppressed by 18 days of treatment with CyA at doses ranging from 3 to 10 mg/kg daily. Without challenge, seven out of 11 animals developed EAU with a median onset of 78 days. This was reduced to 68 days in rats challenged on day 32 with FCA alone, to 48 days with 10 micrograms S antigen in FCA, and to 41 days with 50 micrograms S antigen in FCA. The incidence, onset and severity of anterior uveitis and extent of photoreceptor destruction were related to both CyA dose and nature of challenge. The extent of photoreceptor destruction ran parallel with severity of anterior uveitis; and delayed-type hypersensitivity reactivity on day 43 was related to both severity of anterior uveitis (P less than 0.001) and photoreceptor damage (P less than 0.002). At the highest dose, CyA also delayed the appearance of antibody to S antigen; however, subsequent antibody levels were unrelated to EAU severity or to nature of challenge. The results indicate that CyA-induced suppression of the immunological response to S antigen can recover spontaneously after drug withdrawal, that challenge with either S antigen or FCA alone can accelerate the subsequent onset of EAU, and that these phenomena may provide a basis for investigating mechanisms underlying relapse of human uveoretinitis. Images Fig. 5 PMID:2805414

  17. Electro-thermal modelling of a supercapacitor and experimental validation

    NASA Astrophysics Data System (ADS)

    Berrueta, Alberto; San Martín, Idoia; Hernández, Andoni; Ursúa, Alfredo; Sanchis, Pablo

    2014-08-01

    This paper reports on the electro-thermal modelling of a Maxwell supercapacitor (SC), model BMOD0083 with a rated capacitance of 83 F and rated voltage of 48 V. One electrical equivalent circuit was used to model the electrical behaviour whilst another served to simulate the thermal behaviour. The models were designed to predict the SC operating voltage and temperature, by taking the electric current and ambient temperature as input variables. A five-stage iterative method, applied to three experiments, served to obtain the parameter values for each model. The models were implemented in MATLAB-Simulink®, where they interacted to reciprocally provide information. These models were then validated through a number of tests, subjecting the SC to different current and frequency profiles. These tests included the validation of a bank of supercapacitors integrated into an electric microgrid, in a real operating environment. Satisfactory results were obtained from the electric and thermal models, with RMSE values of less than 0.65 V in all validations.

  18. Redesign of Library Workflows: Experimental Models for Electronic Resource Description.

    ERIC Educational Resources Information Center

    Calhoun, Karen

    This paper explores the potential for and progress of a gradual transition from a highly centralized model for cataloging to an iterative, collaborative, and broadly distributed model for electronic resource description. The purpose is to alert library managers to some experiments underway and to help them conceptualize new methods for defining,…

  19. Early differentiation of the Moon: Experimental and modeling studies

    NASA Technical Reports Server (NTRS)

    Longhi, J.

    1986-01-01

    Major accomplishments include the mapping out of liquidus boundaries of lunar and meteoritic basalts at low pressure; the refinement of computer models that simulate low pressure fractional crystallization; the development of a computer model to calculate high pressure partial melting of the lunar and Martian interiors; and the proposal of a hypothesis of early lunar differentiation based upon terrestrial analogs.

  20. Evaluation of advanced materials through experimental mechanics and modelling

    NASA Technical Reports Server (NTRS)

    Yang, Yii-Ching

    1993-01-01

    Composite materials have been frequently used in aerospace vehicles. Very often defects are inherited during the manufacture and damages are inherited during the construction and services. It becomes critical to understand the mechanical behavior of such composite structure before it can be further used. One good example of these composite structures is the cylindrical bottle of solid rocket motor case with accidental impact damages. Since the replacement of this cylindrical bottle is expensive, it is valuable to know how the damages affects the material, and how it can be repaired. To reach this goal, the damage must be characterized and the stress/strain field must be carefully analyzed. First the damage area, due to impact, is surveyed and identified with a shearography technique which uses the principle of speckle shearing interferometry to measure displacement gradient. Within the damage area of a composite laminate, such as the bottle of solid rocket motor case, all layers are considered to be degraded. Once a lamina being degraded the stiffness as well as strength will be drastically decreased. It becomes a critical area of failure to the whole bottle. And hence the stress/strain field within and around a damage should be accurately evaluated for failure prediction. To investigate the stress/strain field around damages a Hybrid-Numerical method which combines experimental measurement and finite element analysis is used. It is known the stress or strain at the singular point can not be accurately measured by an experimental technique. Nevertheless, if the location is far away from the singular spot, the displacement can be found accurately. Since it reflects the true displacement field locally regardless of the boundary conditions, it is an excellent input data for a finite element analysis to replace the usually assumed boundary conditions. Therefore, the Hybrid-Numerical method is chosen to avoid the difficulty and to take advantage of both experimental

  1. Review: Experimental models for Barrett's esophagus and esophageal adenocarcinoma

    PubMed Central

    Orlando, Roy C.; Chen, Xiaoxin

    2012-01-01

    Several different cell culture systems and laboratory animal models have been used over the years to study Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC). Most of the existing models have key differences with the human esophagus and complex pathogenesis of disease. None of the models offers an ideal system for the complex study of environmental exposure, genetic risk, and prevention strategies. In fact, different model systems may be required to answer different specific research questions about the pathogenesis of BE and EAC. Given the high mortality associated with EAC and the fact that current screening strategies miss most cases of EAC, advances in basic and translational science related to esophageal injury, repair, and carcinogenesis are clearly needed. This review describes several of the existing and potential model systems for BE and EAC with their benefits and disadvantages. PMID:22421618

  2. Experimental models for cancellous bone healing in the rat

    PubMed Central

    Bernhardsson, Magnus; Sandberg, Olof; Aspenberg, Per

    2015-01-01

    Background and purpose — Cancellous bone appears to heal by mechanisms different from shaft fracture healing. There is a paucity of animal models for fractures in cancellous bone, especially with mechanical evaluation. One proposed model consists of a screw in the proximal tibia of rodents, evaluated by pull-out testing. We evaluated this model in rats by comparing it to the healing of empty drill holes, in order to explain its relevance for fracture healing in cancellous bone. To determine the sensitivity to external influences, we also compared the response to drugs that influence bone healing. Methods — Mechanical fixation of the screws was measured by pull-out test and related to the density of the new bone formed around similar, but radiolucent, PMMA screws. The pull-out force was also related to the bone density in drill holes at various time points, as measured by microCT. Results — The initial bone formation was similar in drill holes and around the screw, and appeared to be reflected by the pull-out force. Both models responded similarly to alendronate or teriparatide (PTH). Later, the models became different as the bone that initially filled the drill hole was resorbed to restore the bone marrow cavity, whereas on the implant surface a thin layer of bone remained, making it change gradually from a trauma-related model to an implant fixation model. Interpretation — The similar initial bone formation in the different models suggests that pull-out testing in the screw model is relevant for assessment of metaphyseal bone healing. The subsequent remodeling would not be of clinical relevance in either model. PMID:26200395

  3. A prediction model for ocular damage - Experimental validation.

    PubMed

    Heussner, Nico; Vagos, Márcia; Spitzer, Martin S; Stork, Wilhelm

    2015-08-01

    With the increasing number of laser applications in medicine and technology, accidental as well as intentional exposure of the human eye to laser sources has become a major concern. Therefore, a prediction model for ocular damage (PMOD) is presented within this work and validated for long-term exposure. This model is a combination of a raytracing model with a thermodynamical model of the human and an application which determines the thermal damage by the implementation of the Arrhenius integral. The model is based on our earlier work and is here validated against temperature measurements taken with porcine eye samples. For this validation, three different powers were used: 50mW, 100mW and 200mW with a spot size of 1.9mm. Also, the measurements were taken with two different sensing systems, an infrared camera and a fibre optic probe placed within the tissue. The temperatures were measured up to 60s and then compared against simulations. The measured temperatures were found to be in good agreement with the values predicted by the PMOD-model. To our best knowledge, this is the first model which is validated for both short-term and long-term irradiations in terms of temperature and thus demonstrates that temperatures can be accurately predicted within the thermal damage regime. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Recent advances in animal model experimentation in autism research.

    PubMed

    Tania, Mousumi; Khan, Md Asaduzzaman; Xia, Kun

    2014-10-01

    Autism, a lifelong neuro-developmental disorder is a uniquely human condition. Animal models are not the perfect tools for the full understanding of human development and behavior, but they can be an important place to start. This review focused on the recent updates of animal model research in autism. We have reviewed the publications over the last three decades, which are related to animal model study in autism. Animal models are important because they allow researchers to study the underlying neurobiology in a way that is not possible in humans. Improving the availability of better animal models will help the field to increase the development of medicines that can relieve disabling symptoms. Results from the therapeutic approaches are encouraging remarkably, since some behavioral alterations could be reversed even when treatment was performed on adult mice. Finding an animal model system with similar behavioral tendencies as humans is thus vital for understanding the brain mechanisms, supporting social motivation and attention, and the manner in which these mechanisms break down in autism. The ongoing studies should therefore increase the understanding of the biological alterations associated with autism as well as the development of knowledge-based treatments therapy for those struggling with autism. In this review, we have presented recent advances in research based on animal models of autism, raising hope for understanding the disease biology for potential therapeutic intervention to improve the quality of life of autism individuals.

  5. EO/IR ATR performance modeling to support fusion experimentation

    NASA Astrophysics Data System (ADS)

    Kahler, Barton; Blasch, Erik; Pikas, David J.; Ross, Tim

    2007-04-01

    The identification of a target from an electro-optical or thermal imaging sensor requires accurate sensor registration, quality sensor data, and an exploitation algorithm. Combining the sensor data and exploitation, we are concerned with developing an electro-optical or infrared (EO/IR) performance model. To combat the registration issue, we need a detailed list of operating conditions (i.e. collection position) so that the sensor exploitation results can be evaluated with sensitivities to these operating conditions or collection parameters. The focus of this paper will build on the NVSED AQUIRE model2. We are also concerned with developing an EO/IR model that affords comparable operating condition parameters to a synthetic aperture radar (SAR) performance model. The choice of EO/IR modeling additions are focused on areas were Fusion Gain might be realized through an experiment tradeoff between multiple EO/IR looks for ATR exploitation fusion. The two additions to known EO/IR models discussed in the paper are (1) adjacency and (2) obscuration. The methods to account for these new operating conditions and the corresponding results on the modeled performance are presented in this paper.

  6. Experimental and theoretical study of magnetohydrodynamic ship models.

    PubMed

    Cébron, David; Viroulet, Sylvain; Vidal, Jérémie; Masson, Jean-Paul; Viroulet, Philippe

    2017-01-01

    Magnetohydrodynamic (MHD) ships represent a clear demonstration of the Lorentz force in fluids, which explains the number of students practicals or exercises described on the web. However, the related literature is rather specific and no complete comparison between theory and typical small scale experiments is currently available. This work provides, in a self-consistent framework, a detailed presentation of the relevant theoretical equations for small MHD ships and experimental measurements for future benchmarks. Theoretical results of the literature are adapted to these simple battery/magnets powered ships moving on salt water. Comparison between theory and experiments are performed to validate each theoretical step such as the Tafel and the Kohlrausch laws, or the predicted ship speed. A successful agreement is obtained without any adjustable parameter. Finally, based on these results, an optimal design is then deduced from the theory. Therefore this work provides a solid theoretical and experimental ground for small scale MHD ships, by presenting in detail several approximations and how they affect the boat efficiency. Moreover, the theory is general enough to be adapted to other contexts, such as large scale ships or industrial flow measurement techniques.

  7. [Effects of PAF antagonists in experimental models. Therapeutical perspectives].

    PubMed

    Desquand, S

    1993-01-01

    The discovery, during the last ten years, of Platelet Activating Factor (PAF) antagonists with different frameworks, but efficient on platelets tests, led the authors to study their activity in vivo against PAF-induced effects. These antagonists inhibit, with various potencies, the effects of PAF administration such as hypotension and bronchoconstriction in different animal species. Since PAF is assumed to play a central role in many diseases, effects of its antagonists have been studied in experimentally induced pathologies and in few clinical studies. We have been particularly interested in their effects on the first manifestation of asthma which is hypersensitivity. This manifestation is experimentally reproduced by anaphylactic bronchoconstriction, usually in the guinea-pig. Our results showed that different sensitization procedures may determine the relative efficiency of a PAF antagonist on subsequent antigen challenge. Indeed, the booster injection of antigen to a pre-sensitized animal could account for the refractoriness of anaphylactic bronchoconstriction to PAF antagonists. This booster injection mimics the clinical situation of atopic patients repeatedly exposed to allergen. Thus, it seems that immediate hypersensitivity could not be treated by the unique administration of a PAF antagonist. However, those antagonists may have more benefit in the clinical management of the late phase of asthma and of hyperreactivity and could thus provide anti-asthmatic drugs. PAF antagonists may have also therapeutical effects in septic shock, in myocardial ischemia and cardiac rhythm disturbances, in brain damage following cerebral ischemia and neurological trauma, in gastric and intestinal damages or in some inflammatory reactions.

  8. Experimental and theoretical study of magnetohydrodynamic ship models

    PubMed Central

    Viroulet, Sylvain; Vidal, Jérémie; Masson, Jean-Paul; Viroulet, Philippe

    2017-01-01

    Magnetohydrodynamic (MHD) ships represent a clear demonstration of the Lorentz force in fluids, which explains the number of students practicals or exercises described on the web. However, the related literature is rather specific and no complete comparison between theory and typical small scale experiments is currently available. This work provides, in a self-consistent framework, a detailed presentation of the relevant theoretical equations for small MHD ships and experimental measurements for future benchmarks. Theoretical results of the literature are adapted to these simple battery/magnets powered ships moving on salt water. Comparison between theory and experiments are performed to validate each theoretical step such as the Tafel and the Kohlrausch laws, or the predicted ship speed. A successful agreement is obtained without any adjustable parameter. Finally, based on these results, an optimal design is then deduced from the theory. Therefore this work provides a solid theoretical and experimental ground for small scale MHD ships, by presenting in detail several approximations and how they affect the boat efficiency. Moreover, the theory is general enough to be adapted to other contexts, such as large scale ships or industrial flow measurement techniques. PMID:28665941

  9. Modeling and experimental testing of a smart composite bridge

    NASA Astrophysics Data System (ADS)

    Chandrashekhara, K.; Nanni, Antonio; Watkins, Steve E.; Kumar, Prakash

    2003-10-01

    An all composite bridge with integral sensor network has been designed and built at the University of Missouri-Rolla (UMR). An extensive experimental study and finite element analysis were carried out to obtain and compare properties (stiffness, strength, failure modes) of 76 mm (3 in) square hollow pultruded Fiber Reinforced Polymer (FRP) tubes and their assemblies. Tube assemblies were used in the fabrication of bridge deck designed for H-20 truckloads as specified by the American Association of State Highway and Transportation Officials (AASHTO). The bridge is 9.14 m (30 ft) long and is 2.74 m (9 ft) wide. All the coupons were tested under three- or four-point bending. Experimental results show excellent linear elastic behavior up to failure and are in good agreement with finite element solutions. A quarter portion of the full-sized bridge deck was then tested for its structural performance under design and fatigue loading and also for ultimate load capacity to evaluate the bridge response. The characteristics of the full-size bridge deck were determined by analyzing the performed tests. The test sample showed almost no reduction in stiffness or strength after 2 million cycles of fatigue loading in excess of the design load. The bridge was installed at the UMR campus in July 2000. The bridge is equipped with fiber optic sensors, and the response of the bridge will be remotely monitored.

  10. Fantastic animals as an experimental model to teach animal adaptation

    PubMed Central

    Guidetti, Roberto; Baraldi, Laura; Calzolai, Caterina; Pini, Lorenza; Veronesi, Paola; Pederzoli, Aurora

    2007-01-01

    Background Science curricula and teachers should emphasize evolution in a manner commensurate with its importance as a unifying concept in science. The concept of adaptation represents a first step to understand the results of natural selection. We settled an experimental project of alternative didactic to improve knowledge of organism adaptation. Students were involved and stimulated in learning processes by creative activities. To set adaptation in a historic frame, fossil records as evidence of past life and evolution were considered. Results The experimental project is schematized in nine phases: review of previous knowledge; lesson on fossils; lesson on fantastic animals; planning an imaginary world; creation of an imaginary animal; revision of the imaginary animals; adaptations of real animals; adaptations of fossil animals; and public exposition. A rubric to evaluate the student's performances is reported. The project involved professors and students of the University of Modena and Reggio Emilia and of the "G. Marconi" Secondary School of First Degree (Modena, Italy). Conclusion The educational objectives of the project are in line with the National Indications of the Italian Ministry of Public Instruction: knowledge of the characteristics of living beings, the meanings of the term "adaptation", the meaning of fossils, the definition of ecosystem, and the particularity of the different biomes. At the end of the project, students will be able to grasp particular adaptations of real organisms and to deduce information about the environment in which the organism evolved. This project allows students to review previous knowledge and to form their personalities. PMID:17767729

  11. Flow of a blood analogue fluid in a compliant abdominal aortic aneurysm model: experimental modelling.

    PubMed

    Deplano, Valérie; Knapp, Yannick; Bailly, Lucie; Bertrand, Eric

    2014-04-11

    The aim of this work is to develop a unique in vitro set-up in order to analyse the influence of the shear thinning fluid-properties on the flow dynamics within the bulge of an abdominal aortic aneurysm (AAA). From an experimental point of view, the goals are to elaborate an analogue shear thinning fluid mimicking the macroscopic blood behaviour, to characterise its rheology at low shear rates and to propose an experimental device able to manage such an analogue fluid without altering its feature while reproducing physiological flow rate and pressure, through compliant AAA. Once these experimental prerequisites achieved, the results obtained in the present work show that the flow dynamics is highly dependent on the fluid rheology. The main results point out that the propagation of the vortex ring, generated in the AAA bulge, is slower for shear thinning fluids inducing a smaller travelled distance by the vortex ring so that it never impacts the anterior wall in the distal region, in opposition to Newtonian fluids. Moreover, scalar shear rate values are globally lower for shear thinning fluids inducing higher maximum stress values than those for the Newtonian fluids. Consequently, this work highlights that a Newtonian fluid model is finally inadequate to obtain a reliable prediction of the flow dynamics within AAA.

  12. Pore water pressure variations in Subpermafrost groundwater : Numerical modeling compared with experimental modeling

    NASA Astrophysics Data System (ADS)

    Rivière, Agnès.; Goncalves, Julio; Jost, Anne; Font, Marianne

    2010-05-01

    Development and degradation of permafrost directly affect numerous hydrogeological processes such as thermal regime, exchange between river and groundwater, groundwater flows patterns and groundwater recharge (Michel, 1994). Groundwater in permafrost area is subdivided into two zones: suprapermafrost and subpermafrost which are separated by permafrost. As a result of the volumetric expansion of water upon freezing and assuming ice lenses and frost heave do not form freezing in a saturated aquifer, the progressive formation of permafrost leads to the pressurization of the subpermafrost groundwater (Wang, 2006). Therefore disappearance or aggradation of permafrost modifies the confined or unconfined state of subpermafrost groundwater. Our study focuses on modifications of pore water pressure of subpermafrost groundwater which could appear during thawing and freezing of soil. Numerical simulation allows elucidation of some of these processes. Our numerical model accounts for phase changes for coupled heat transport and variably saturated flow involving cycles of freezing and thawing. The flow model is a combination of a one-dimensional channel flow model which uses Manning-Strickler equation and a two-dimensional vertically groundwater flow model using Richards equation. Numerical simulation of heat transport consisted in a two dimensional model accounting for the effects of latent heat of phase change of water associated with melting/freezing cycles which incorporated the advection-diffusion equation describing heat-transfer in porous media. The change of hydraulic conductivity and thermal conductivity are considered by our numerical model. The model was evaluated by comparing predictions with data from laboratory freezing experiments. Experimental design was undertaken at the Laboratory M2C (Univesité de Caen-Basse Normandie, CNRS, France). The device consisted of a Plexiglas box insulated on all sides except on the top. Precipitation and ambient temperature are

  13. An experimental animal model for abdominal fascia healing after surgery.

    PubMed

    Burcharth, J; Pommergaard, H-C; Klein, M; Rosenberg, J

    2013-01-01

    Incisional hernia (IH) is a well-known complication after abdominal surgical procedures. The exact etiology of IH is still unknown even though many risk factors have been suggested. The aim of this study was to create an animal model of a weakly healed abdominal fascia that could be used to evaluate the actively healing fascia. Such an animal model may promote future research in the prevention of IH. 86 male Sprague-Dawley rats were used to establish a model involving six experiments (experiments A-F). Mechanical testing of the breaking strength of the healed fascia was performed by testing tissue strips from the healed fascia versus the unincised control fascia 7 and 28 days postoperatively. During the six experiments a healing model was created that produced significantly weaker coherent fascia when compared with the control tissue measured in terms of mechanical breaking strength. This new animal model employed myofascial closing after a full thickness abdominal incision using a running suture with fast-absorbable suture material. This technique produced a weak myofascial layer compared with the control tissue measured in terms of breaking strength after both 7 and 28 days. It was possible to create a healed but weak abdominal fascia in rats with a minimum of defects after incision using a running suture technique in the fascia. In contrast to other models, regular tissue defects were absent, and the model can therefore be used to evaluate the changes, both histological and mechanical, in the actively healing fascia, which may lead to incisional herniation. Furthermore, the model may also be used to study interventions performed to promote healing. This contrasts with existing models with regular fascia defects, which are not well suited for this purpose. © 2013 S. Karger AG, Basel.

  14. A model of the mammalian optic nerve fibre based on experimental data.

    PubMed

    Oozeer, M; Veraart, C; Legat, V; Delbeke, J

    2006-08-01

    Several experimental data about membrane dynamics and pharmacological sensitivities of optic nerve axons have been published. The present work summarizes these data and computer simulations have been used to develop a model of the mammalian optic nerve fibre. The ionic currents description were derived from existing membrane models and particularly from a model of the somatic retinal ganglion cell (RGC) impulse generation. However, original equations had to be modified to match experimental data, which suggests that in RGCs, axonal and somatic ion channel expression are different. The new model is consistent with recent experimental results about optic nerve axonal excitability.

  15. Pulmonary Fluid Flow Challenges for Experimental and Mathematical Modeling

    PubMed Central

    Levy, Rachel; Hill, David B.; Forest, M. Gregory; Grotberg, James B.

    2014-01-01

    Modeling the flow of fluid in the lungs, even under baseline healthy conditions, presents many challenges. The complex rheology of the fluids, interaction between fluids and structures, and complicated multi-scale geometry all add to the complexity of the problem. We provide a brief overview of approaches used to model three aspects of pulmonary fluid and flow: the surfactant layer in the deep branches of the lung, the mucus layer in the upper airway branches, and closure/reopening of the airway. We discuss models of each aspect, the potential to capture biological and therapeutic information, and open questions worthy of further investigation. We hope to promote multi-disciplinary collaboration by providing insights into mathematical descriptions of fluid-mechanics in the lung and the kinds of predictions these models can make. PMID:25096289

  16. Dynamic modelling and experimental validation of three wheeled tilting vehicles

    NASA Astrophysics Data System (ADS)

    Amati, Nicola; Festini, Andrea; Pelizza, Luigi; Tonoli, Andrea

    2011-06-01

    The present paper describes the study of the stability in the straight running of a three-wheeled tilting vehicle for urban and sub-urban mobility. The analysis was carried out by developing a multibody model in the Matlab/SimulinkSimMechanics environment. An Adams-Motorcycle model and an equivalent analytical model were developed for the cross-validation and for highlighting the similarities with the lateral dynamics of motorcycles. Field tests were carried out to validate the model and identify some critical parameters, such as the damping on the steering system. The stability analysis demonstrates that the lateral dynamic motions are characterised by vibration modes that are similar to that of a motorcycle. Additionally, it shows that the wobble mode is significantly affected by the castor trail, whereas it is only slightly affected by the dynamics of the front suspension. For the present case study, the frame compliance also has no influence on the weave and wobble.

  17. Experimental analysis and modeling of a stormwater perlite filter.

    PubMed

    Gironás, Jorge; Adriasola, José M; Fernández, Bonifacio

    2008-06-01

    This paper presents the study of a mixed porous media composed of expanded perlite and a nonwoven needle-punched geotextile used to reduce the suspended solids load and concentration in urban runoff. Laboratory procedures were designed to quantify the suspended solids removal efficiency and variation in time of filtration rate. Different grain-size distributions of expanded perlite, diverse suspended solids concentrations, and different hydraulic and geometric conditions were tested to determine the most effective filter media. A dimensionless parameter, termed Global Performance Index (GPI), was developed to reach this objective. Measured data were also used to build a dimensional and a regression model to represent the performance of the filter media mathematically. The theory, derivation, and performance of both models are presented and compared with an existent empirical model. The dimensional model better reproduces the observations, becoming a useful tool for the design, operation, and evaluation of commercial porous media filters.

  18. EXPERIMENTAL MODELS FOR THE STUDY OF ORAL CLEFTS

    EPA Science Inventory

    Toxicology and teratology studies routinely utilize animal models to determine the potential for chemical and physical agents to produce reproductive and developmental toxicity, including birth defects such as cleft palate. The standardized teratology screen typically tests co...

  19. EXPERIMENTAL MODELS FOR THE STUDY OF ORAL CLEFTS

    EPA Science Inventory

    Toxicology and teratology studies routinely utilize animal models to determine the potential for chemical and physical agents to produce reproductive and developmental toxicity, including birth defects such as cleft palate. The standardized teratology screen typically tests co...

  20. Avian necrotic enteritis: Experimental models, climate change, and vaccine development

    USDA-ARS?s Scientific Manuscript database

    This review summarizes recent developments in disease models, pathogenesis, host immunity, risk factors, and vaccine development for Clostridium perfringens infection of poultry and necrotic enteritis (NE). The increasing trends of legislative restrictions and voluntary removal of antibiotic growth...

  1. New experimental models of skin homeostasis and diseases.

    PubMed

    Larcher, F; Espada, J; Díaz-Ley, B; Jaén, P; Juarranz, A; Quintanilla, M

    2015-01-01

    Homeostasis, whose regulation at the molecular level is still poorly understood, is intimately related to the functions of epidermal stem cells. Five research groups have been brought together to work on new in vitro and in vivo skin models through the SkinModel-CM program, under the auspices of the Spanish Autonomous Community of Madrid. This project aims to analyze the functions of DNA methyltransferase 1, endoglin, and podoplanin in epidermal stem cell activity, homeostasis, and skin cancer. These new models include 3-dimensional organotypic cultures, immunodeficient skin-humanized mice, and genetically modified mice. Another aim of the program is to use skin-humanized mice to model dermatoses such as Gorlin syndrome and xeroderma pigmentosum in order to optimize new protocols for photodynamic therapy. Copyright © 2013 Elsevier España, S.L.U. and AEDV. All rights reserved.

  2. An experimental test of plant canopy reflectance models on cotton

    NASA Technical Reports Server (NTRS)

    Lemaster, E. W.

    1974-01-01

    Extensive data on the plant parameters necessary to evaluate any model are presented for a cotton crop. The variation of the bidirectional reflectance function with observer altitude, observer azimuth, and sun altitude angle is presented for a high density cotton crop having leaf index of 19. A comparison with the quantitative behavior obtained from the Suits model is accomplished in the wavelength region from 400 nm to 1050 nm.

  3. Europium anomaly in plagioclase feldspar - Experimental results and semiquantitative model.

    NASA Technical Reports Server (NTRS)

    Weill, D. F.; Drake, M. J.

    1973-01-01

    The partition of europium between plagioclase feldspar and magmatic liquid is considered in terms of the distribution coefficients for divalent and trivalent europium. A model equation is derived giving the europium anomaly in plagioclase as a function of temperature and oxygen fugacity. The model explains europium anomalies in plagioclase synthesized under controlled laboratory conditions as well as the variations of the anomaly observed in natural terrestrial and extraterrestrial igneous rocks.

  4. Experimental test of contemporary mathematical models of visual letter recognition.

    PubMed

    Townsend, J T; Ashby, F G

    1982-12-01

    A letter confusion experiment that used brief durations manipulated payoffs across the four stimulus letters, which were composed of line segments equal in length. The observers were required to report the features they perceived as well as to give a letter response. The early feature-sampling process is separated from the later letter-decision process in the substantive feature models, and predictions are thus obtained for the frequencies of feature report as well as letter report. Four substantive visual feature-processing models are developed and tested against one another and against three models of a more descriptive nature. The substantive models predict the decisional letter report phase much better than they do the feature-sampling phase, but the best overall 4 X 4 letter confusion matrix fits are obtained with one of the descriptive models, the similarity choice model. The present and other recent results suggest that the assumption that features are sampled in a stochastically independent manner may not be generally valid. The traditional high-threshold conceptualization of feature sampling is also falsified by the frequent reporting by observers of features not contained in the stimulus letter.

  5. Experimental disease models for the assessment of meningococcal vaccines.

    PubMed

    Gorringe, A R; Reddin, K M; Funnell, S G; Johansson, L; Rytkönen, A; Jonsson, A-B

    2005-03-18

    Animal infection models are valuable for the development and preclinical assessment of meningococcal vaccines in the absence of clear in vitro correlates of protection for protein-based serogroup B vaccines. It is only in animal models that interactions of the organism with the innate, humoral and cellular immune systems can be assessed. However, humans are the only natural host for Neisseria meningitidis and there is no ideal disease model using laboratory animals that mimics the course of human disease. The two most widely used models are intraperitoneal (i.p.) infection of adult mice or infant rats. The mouse i.p. infection model requires an exogenous iron source (e.g. human transferrin) to obtain a lethal bacteraemic infection and can be used to assess both active and passive immunisation. The virulence of wild-type and knockout mutants can also be compared. i.p. infection of infant rats has been used to assess passive protection provided by sera raised against vaccine candidates or human vaccine sera. However, the duration of bacteraemia is short, mortality is low and active protection cannot be assessed. Recent developments using transgenic mice expressing human CD46 give hope that improved models will be developed.

  6. Use of field experimental studies to evaluate emergency response models

    SciTech Connect

    Gudiksen, P.H.; Lange, R.; Rodriguez, D.J.; Nasstrom, J.S.

    1985-07-16

    The three-dimensional diagnostic wind field model (MATHEW) and the particle-in-cell atmospheric transport and diffusion model (ADPIC) are used by the Atmospheric Release Advisory Capability to estimate the environmental consequences of accidental releases of radioactivity into the atmosphere. These models have undergone extensive evaluations against field experiments conducted in a variety of environmental settings ranging from relatively flat to very complex terrain areas. Simulations of tracer experiments conducted in a complex mountain valley setting revealed that 35 to 50% of the comparisons between calculated and measured tracer concentrations were within a factor of 5. This may be compared with a factor of 2 for 50% of the comparisons for relatively flat terrain. This degradation of results in complex terrain is due to a variety of factors such as the limited representativeness of measurements in complex terrain, the limited spatial resolution afforded by the models, and the turbulence parameterization based on sigma/sub theta/ measurements to evaluate the eddy diffusivities. Measurements of sigma/sub theta/ in complex terrain exceed those measured over flat terrain by a factor of 2 to 3 leading to eddy diffusivities that are unrealistically high. The results of model evaluations are very sensitive to the quality and the representativeness of the meteorological data. This is particularly true for measurements near the source. The capability of the models to simulate the dispersion of an instantaneously produced cloud of particulates was illustrated to be generally within a factor of 2 over flat terrain. 19 refs., 16 figs.

  7. Experimental investigation and constitutive model for lime mudstone.

    PubMed

    Wang, Junbao; Liu, Xinrong; Zhao, Baoyun; Song, Zhanping; Lai, Jinxing

    2016-01-01

    In order to investigate the mechanical properties of lime mudstone, conventional triaxial compression tests under different confining pressures (0, 5, 15 and 20 MPa) are performed on lime mudstone samples. The test results show that, from the overall perspective of variation law, the axial peak stress, axial peak strain and elastic modulus of lime mudstone tend to gradually increase with increasing confining pressure. In the range of tested confining pressure, the variations in axial peak stress and elastic modulus with confining pressure can be described with linear functions; while the variation in axial peak strain with confining pressure can be reflected with a power function. To describe the axial stress-strain behavior in failure process of lime mudstone, a new constitutive model is proposed, with the model characteristics analyzed and the parameter determination method put forward. Compared with Wang' model, only one parameter n is added to the new model. The comparison of predicted curves from the model and test data indicates that the new model can preferably simulate the strain softening property of lime mudstone and the axial stress-strain response in rock failure process.

  8. Experimental validation of different modeling approaches for solid particle receivers.

    SciTech Connect

    Khalsa, Siri Sahib S.; Amsbeck, Lars , Spain and Stuttgart, Germany); Roger, Marc , Spain and Stuttgart, Germany); Siegel, Nathan Phillip; Kolb, Gregory J.; Buck, Reiner , Spain and Stuttgart, Germany); Ho, Clifford Kuofei

    2009-07-01

    Solid particle receivers have the potential to provide high-temperature heat for advanced power cycles, thermochemical processes, and thermal storage via direct particle absorption of concentrated solar energy. This paper presents two different models to evaluate the performance of these systems. One model is a detailed computational fluid dynamics model using FLUENT that includes irradiation from the concentrated solar flux, two-band re-radiation and emission within the cavity, discrete-phase particle transport and heat transfer, gas-phase convection, wall conduction, and radiative and convective heat losses. The second model is an easy-to-use and fast simulation code using Matlab that includes solar and thermal radiation exchange between the particle curtain, cavity walls, and aperture, but neglects convection. Both models were compared to unheated particle flow tests and to on-sun heating tests. Comparisons between measured and simulated particle velocities, opacity, particle volume fractions, particle temperatures, and thermal efficiencies were found to be in good agreement. Sensitivity studies were also performed with the models to identify parameters and modifications to improve the performance of the solid particle receiver.

  9. Experimental Investigation and Modeling of Integrated Tri-generation Systems

    NASA Astrophysics Data System (ADS)

    Cetinkaya, Eda

    Energy demand in the world is increasing with population growth and higher living standards. Today, the need for energy requires a focus on renewable sources without abandoning fossil fuels. Efficient use of energy is one of the most important tasks in modern energy systems to achieve. In addition to the energy need, growing environmental concerns are linked with energy is emerged. Multi-purpose energy generation allows a higher efficiency by generating more outputs with the same input in the same system. Tri-generation systems are expected to provide at least three commodities, such as heating, cooling, desalination, storable fuel production and some other useful outputs, in addition to power generation. In this study, an experimental investigation of gasification is presented and two integrated tri-generation systems are proposed. The first integrated tri-generation system (System 1) utilizes solar energy as input and the outputs are power, fresh water and hot water. It consists of four sub-systems, namely solar power tower system, desalination system, Rankine cycle and organic Rankine cycle (ORC). The second integrated tri-generation system (System 2) utilizes coal and biomass as input and the outputs are power, fuel and hot water. It consists of five sub-systems: gasification plant, Brayton cycle, Rankine cycle, Fischer-Tropsch synthesis plant and an organic Rankine cycle (ORC). Experimental investigation includes coal and biomass gasification, where the experimental results of synthesis gas compositions are utilized in the analysis of the second systems. To maximize efficiency, heat losses from the system should be minimized through a recovery system to make the heat a useful commodity for other systems, such as ORCs which can utilize the low-grade heat. In this respect, ORCs are first analyzed for three different configurations in terms of energy and exergy efficiencies altering working fluids to increase the power output. Among two types of coal and one type

  10. Experimental animal models for COPD: a methodological review.

    PubMed

    Ghorani, Vahideh; Boskabady, Mohammad Hossein; Khazdair, Mohammad Reza; Kianmeher, Majid

    2017-01-01

    Chronic obstructive pulmonary disease (COPD) is a progressive disorder that makes the breathing difficult and is characterized by pathological conditions ranging from chronic inflammation to tissue proteolysis. With regard to ethical issues related to the studies on patients with COPD, the use of animal models of COPD is inevitable. Animal models improve our knowledge about the basic mechanisms underlying COPD physiology, pathophysiology and treatment. Although these models are only able to mimic some of the features of the disease, they are valuable for further investigation of mechanisms involved in human COPD. We searched the literature available in Google Scholar, PubMed and ScienceDirect databases for English articles published until November 2015. For this purpose, we used 5 keywords for COPD, 3 for animal models, 4 for exposure methods, 3 for pathophysiological changes and 3 for biomarkers. One hundred and fifty-one studies were considered eligible for inclusion in this review. According to the reviewed articles, animal models of COPD are mainly induced in mice, guinea pigs and rats. In most of the studies, this model was induced by exposure to cigarette smoke (CS), intra-tracheal lipopolysaccharide (LPS) and intranasal elastase. There were variations in time course and dose of inducers used in different studies. The main measured parameters were lung pathological data and lung inflammation (both inflammatory cells and inflammatory mediators) in most of the studies and tracheal responsiveness (TR) in only few studies. The present review provides various methods used for induction of animal models of COPD, different animals used (mainly mice, guinea pigs and rats) and measured parameters. The information provided in this review is valuable for choosing appropriate animal, method of induction and selecting parameters to be measured in studies concerning COPD.

  11. Nonarteritic anterior ischemic optic neuropathy (NAION) and its experimental models

    PubMed Central

    Bernstein, Steven L.; Johnson, Mary A.; Miller, Neil R.

    2011-01-01

    Anterior ischemic optic neuropathy (AION) can be divided into nonarteritic (NAION) and arteritic (AAION) forms. NAION makes up ~85% of all cases of AION, and until recently was poorly understood. There is no treatment for NAION, and its initiating causes are poorly understood, in part because NAION is not lethal, making it difficult to obtain fresh, newly affected tissue for study. In-vivo electrophysiology and post-mortem studies reveal specific responses that are associated with NAION. New models of NAION have been developed which enable insights into the pathophysiological events surrounding this disease. These models include both rodent and primate species, and the power of a `vertically integrated' multi-species approach can help in understanding the common cellular mechanisms and physiological responses to clinical NAION, and to identify potential approaches to treatment. The models utilize laser light to activate intravascular photoactive dye to induce capillary vascular thrombosis, while sparing the larger vessels. The observable optic nerve changes associated with rodent models of AION (rAION) and primate NAION (pNAION) are indistinguishable from that seen in clinical disease, including sectoral axonal involvement, and in-vivo electrophysiological data from these models are consistent with clinical data. Early post-infarct events reveal an unexpected inflammatory response, and changes in intraretinal gene expression for both stress response, while sparing outer retinal function, which occurs in AAION models. Histologically, the NAION models reveal an isolated loss of retinal ganglion cells by apoptosis. There are changes detectable by immunohistochemistry suggesting that other retinal cells mount a brisk response to retinal ganglion cell distress without themselves dying. The optic nerve ultimately shows axonal loss and scarring. Inflammation is a prominent early histological feature. This suggests that clinically, specific modulation of inflammation may

  12. Structural-acoustic modeling of automotive vehicles in presence of uncertainties and experimental identification and validation.

    PubMed

    Durand, Jean-François; Soize, Christian; Gagliardini, Laurent

    2008-09-01

    The design of cars is mainly based on the use of computational models to analyze structural vibrations and internal acoustic levels. Considering the very high complexity of such structural-acoustic systems, and in order to improve the robustness of such computational structural-acoustic models, both model uncertainties and data uncertainties must be taken into account. In this context, a probabilistic approach of uncertainties is implemented in an adapted computational structural-acoustic model. The two main problems are the experimental identification of the parameters controlling the uncertainty levels and the experimental validation. Relevant experiments have especially been developed for this research in order to constitute an experimental database devoted to structural vibrations and internal acoustic pressures. This database is used to perform the experimental identification of the probability model parameters and to validate the stochastic computational model.

  13. Design and modeling considerations for experimental railgun armatures

    SciTech Connect

    Sink, D.A. ); Krzastek, L.J. )

    1991-01-01

    This paper reports on the present status of railgun tests at various laboratories indicates that performance improvements which are not occurring as expected to advance toward higher velocities. There could be two reasons for this. First, the number of experiments and test data are too limited to indicate future testing needs. Second, the applications of models to predict operating parameters are not reliable and generally overpredict velocities. These two reasons are strongly coupled and, with a focused concentration in these areas, the desired advances will have a better chance of occurring. The authors have developed a calculational model which accounts for the dynamics of the motion, as well as the physics of the armature, the balance of energy and mass flow, and voltage and B-dot data. The following is a discussion of this model for calculating performance. The model is general and has been directly applied to the study and simulation of existing data. Modeling features, calculational results, aspects of the physics, and analyzes of gun performance are presented.

  14. Experimental models of renal calcium stones in rodents

    PubMed Central

    Bilbault, Héloïse; Haymann, Jean-Philippe

    2016-01-01

    In human nephrolithiasis, most stones are containing calcium and are located within urinary cavities; they may contain monohydrate calcium oxalate, dihydrate calcium oxalate and/or calcium phosphates in various proportion. Nephrolithiasis may also be associated with nephrocalcinosis, i.e., crystal depositions in tubular lumen and/or interstitium, an entity which suggests specific pathological processes. Several rodents models have been developed in order to study the pathophysiology of intrarenal crystal formation. We review here calcium rodent models classified upon the presence of nephrolithiasis and/or nephrocalcinosis. As rodents are not prone to nephrolithiasis, models require the induction of a long standing hypercalciuria or hyperoxaluria (thus explaining the very few studies reported), conversely to nephrocalcinosis which may occur within hours or days. Whereas a nephrotoxicity leading to tubular injury and regeneration appears as a critical event for crystal retention in nephrocalcinosis models, surprisingly very little is known about the physiopathology of crystal attachment to urothelium in nephrolithiasis. Creating new models of nephrolithiasis especially in different genetic mice strains appears an important challenge in order to unravel the early mechanisms of urinary stone formation in papilla and fornices. PMID:26981444

  15. New experimental model of terminal aneurysms in Swine: technical note.

    PubMed

    Yatomi, Kenji; Yamamoto, Munetaka; Mitome-Mishima, Yumiko; Nonaka, Sensyu; Yoshida, Kensaku; Oishi, Hidenori; Arai, Hajime

    2012-11-01

    Animal models of intracranial aneurysms are important for training surgeons and creating innovative endovascular treatment. Swine have physical dimensions close to those of humans and so are widely used in cardiology research. swine used as models for intracranial aneurysms have had difficulty maintaining long-term aneurysm patency. We present a swine model that may allow researchers to follow long-term outcomes after endovascular treatment. We developed a terminal aneurysm model in swine (n = 3) using a vein pouch of an end-to-side anastomosis of the right carotid artery. We anastomosed the left carotid artery end and the right carotid artery side, designing it so the blood flows into the aneurysmal neck directly from the opposite side. we also anastomosed the ascending cervical artery and the right carotid artery, with flow reversal in the proximal right carotid artery by ligating the more proximal side. At the same time, a side-wall aneurysm was made, and we compared their patency periods. The terminal aneurysms remained patent for 3 months, and there were no major changes in their size or shape. In contrast, the side-wall aneurysms had become occluded at the 1-month follow-up. Our swine model displayed long-term patency and has the potential to allow long-term evaluation of new techniques and embolic agents. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  16. Mouse models of advanced spontaneous metastasis for experimental therapeutics

    PubMed Central

    Francia, Giulio; Cruz-Munoz, William; Man, Shan; Xu, Ping; Kerbel, Robert S.

    2015-01-01

    An enduring problem in cancer research is the failure to reproduce highly encouraging preclinical therapeutic findings using transplanted or spontaneous primary tumours in mice in clinical trials of patients with advanced metastatic disease. There are several reasons for this, including the failure to model established, visceral metastatic disease. We therefore developed various models of aggressive multi-organ spontaneous metastasis after surgical resection of orthotopically transplanted human tumour xenografts. In this Opinion article we provide a personal perspective summarizing the prospect of their increased clinical relevance. This includes the reduced efficacy of certain targeted anticancer drugs, the late emergence of spontaneous brain metastases and the clinical trial results evaluating a highly effective therapeutic strategy previously tested using such models. PMID:21258397

  17. Understanding Diabetes Population Dynamics Through Simulation Modeling and Experimentation

    PubMed Central

    Jones, Andrew P.; Homer, Jack B.; Murphy, Dara L.; Essien, Joyce D. K.; Milstein, Bobby; Seville, Donald A.

    2006-01-01

    Health planners in the Division of Diabetes Translation and others from the National Center for Chronic Disease Prevention and Health Promotion of the Centers for Disease Control and Prevention used system dynamics simulation modeling to gain a better understanding of diabetes population dynamics and to explore implications for public health strategy. A model was developed to explain the growth of diabetes since 1980 and portray possible futures through 2050. The model simulations suggest characteristic dynamics of the diabetes population, including unintended increases in diabetes prevalence due to diabetes control, the inability of diabetes control efforts alone to reduce diabetes-related deaths in the long term, and significant delays between primary prevention efforts and downstream improvements in diabetes outcomes. PMID:16449587

  18. Understanding diabetes population dynamics through simulation modeling and experimentation.

    PubMed

    Jones, Andrew P; Homer, Jack B; Murphy, Dara L; Essien, Joyce D K; Milstein, Bobby; Seville, Donald A

    2006-03-01

    Health planners in the Division of Diabetes Translation and others from the National Center for Chronic Disease Prevention and Health Promotion of the Centers for Disease Control and Prevention used system dynamics simulation modeling to gain a better understanding of diabetes population dynamics and to explore implications for public health strategy. A model was developed to explain the growth of diabetes since 1980 and portray possible futures through 2050. The model simulations suggest characteristic dynamics of the diabetes population, including unintended increases in diabetes prevalence due to diabetes control, the inability of diabetes control efforts alone to reduce diabetes-related deaths in the long term, and significant delays between primary prevention efforts and downstream improvements in diabetes outcomes.

  19. Laser ablation of a turbid medium: Modeling and experimental results

    SciTech Connect

    Brygo, F.; Semerok, A.; Weulersse, J.-M.; Thro, P.-Y.; Oltra, R.

    2006-08-01

    Q-switched Nd:YAG laser ablation of a turbid medium (paint) is studied. The optical properties (absorption coefficient, scattering coefficient, and its anisotropy) of a paint are determined with a multiple scattering model (three-flux model), and from measurements of reflection-transmission of light through thin layers. The energy deposition profiles are calculated at wavelengths of 532 nm and 1.064 {mu}m. They are different from those described by a Lambert-Beer law. In particular, the energy deposition of the laser beam is not maximum on the surface but at some depth inside the medium. The ablated rate was measured for the two wavelengths and compared with the energy deposition profile predicted by the model. This allows us to understand the evolution of the ablated depth with the wavelength: the more the scattering coefficient is higher, the more the ablated depth and the threshold fluence of ablation decrease.

  20. An experimental study on a model Stirling engine car

    SciTech Connect

    Sohma, Yutaka; Wu, Chungming; Isshiki, Seita; Ushiyama, Izumi

    1999-07-01

    A Stirling engine is a mechanical device that operates on a closed regenerative thermodynamic cycle, with cyclic compression and expansion of the working fluid at different temperature levels. The flow is controlled by volume changes, and there exists a net conversion of the heat to work. Stirling engines are ideally suited to off-grid electric power generation because of their multi-fuel capability, potentially high efficiency and low noise. The first model Stirling Techno-rally was held in August 1997 for further promotion of the clean and quiet Stirling engine as one of the Centennial Anniversary events of JSME. In the race, more than one hundred cars competed for the time on a course of 13 meters length and 30 centimeters width. In Ashikaga Institute of Technology, a model Stirling engine car Ashikaga Gekkoh was made for this event. In this paper the authors report on this model car that won the championship of the Stirling Techno-rally.

  1. Backlash Detection in Geared Mechanisms: Modeling, Simulation, and Experimentation

    NASA Astrophysics Data System (ADS)

    Sarkar, N.; Ellis, R. E.; Moore, T. N.

    1997-05-01

    Backlash is a common fault that occurs in geared mechanisms, and can produce inaccuracy or uncontrollability of the mechanism. It is shown that, by modeling backlash as a microscopic impact, its presence can be detected and possibly measured using only simple sensors. The first stage of modeling establishes the need for the use of non-linear elastic sensors and damping forces in calculating the gear teeth reaction force. The second stage of modeling used a detailed digital multibody simulation to develop and test the effectiveness of the proposed detection approach. Experiments verify the efficacy of the methodology in practice. Finally, the results can be quantified for a test-bed mechanism, indicating that this methodology may be useful for condition monitoring of industrial mechanisms.

  2. Cellulose and the twofold screw axis: Modeling and experimental arguments

    USDA-ARS?s Scientific Manuscript database

    Crystallography indicates that molecules in crystalline cellulose either have 2-fold screw-axis (21) symmetry or closely approximate it, leading to short distances between H4 and H1' across the glycosidic linkage. Therefore, modeling studies of cellobiose often show elevated energies for 21 structur...

  3. Experimental models of communication at the molecular and microsystemic levels.

    NASA Technical Reports Server (NTRS)

    Fox, S. W.; Hsu, L.; Brooke, S.; Nakashima, T.; Lacey, J. C., Jr.

    1972-01-01

    Communication at both the macromolecular and the (supramacromolecular) microsystemic levels has been demonstrated in artificial polymers and artificial systems. These phenomena are models for communication in evolving and contemporary systems. The significance of a combination of communication at the two levels is emphasized.

  4. Chemically induced skin carcinogenesis: Updates in experimental models (Review)

    PubMed Central

    NEAGU, MONICA; CARUNTU, CONSTANTIN; CONSTANTIN, CAROLINA; BODA, DANIEL; ZURAC, SABINA; SPANDIDOS, DEMETRIOS A.; TSATSAKIS, ARISTIDIS M.

    2016-01-01

    Skin cancer is one of the most common malignancies affecting humans worldwide, and its incidence is rapidly increasing. The study of skin carcinogenesis is of major interest for both scientific research and clinical practice and the use of in vivo systems may facilitate the investigation of early alterations in the skin and of the mechanisms involved, and may also lead to the development of novel therapeutic strategies for skin cancer. This review outlines several aspects regarding the skin toxicity testing domain in mouse models of chemically induced skin carcinogenesis. There are important strain differences in view of the histological type, development and clinical evolution of the skin tumor, differences reported decades ago and confirmed by our hands-on experience. Using mouse models in preclinical testing is important due to the fact that, at the molecular level, common mechanisms with human cutaneous tumorigenesis are depicted. These animal models resemble human skin cancer development, in that genetic changes caused by carcinogens and pro-inflammatory cytokines, and simultaneous inflammation sustained by pro-inflammatory cytokines and chemokines favor tumor progression. Drugs and environmental conditions can be tested using these animal models. keeping in mind the differences between human and rodent skin physiology. PMID:26986013

  5. Pristane-induced lupus: considerations on this experimental model.

    PubMed

    Freitas, Eduarda Correa; de Oliveira, Mayara Souza; Monticielo, Odirlei André

    2017-09-06

    Systemic lupus erythematosus (SLE) is a multifactorial, autoimmune inflammatory disease with pleomorphic clinical manifestations involving different organs and tissues. The etiology of this disease has been associated with a dysfunctional response of B and T lymphocytes against environmental stimuli in individuals genetically susceptible to SLE, which determines an immune response against different autoantigens and, consequently, tissue damage. The study of different murine models has provided a better understanding of these autoimmune phenomena. This review primarily focuses on that has been learned from the pristane-induced lupus (PIL) model and how this model can be used to supplement recent advances in understanding the pathogenesis of SLE. We also consider both current and future therapies for this disease. The PubMed, SciELO, and Embase databases were searched for relevant articles published from 1950 to 2016. PIL has been shown to be a useful tool for understanding the multiple mechanisms involved in systemic autoimmunity. In addition, it can be considered an efficient model to evaluate the environmental contributions and interferon signatures present in patients with SLE.

  6. Experimental and numerical modeling of shrub crown fire initiation

    Treesearch

    Watcharapong Tachajapong; Jesse Lozano; Shakar Mahalingam; Xiangyang Zhou; David Weise

    2009-01-01

    The transition of fire from dry surface fuels to wet shrub crown fuels was studied using laboratory experiments and a simple physical model to gain a better understanding of the transition process. In the experiments, we investigated the effects of varying vertical distances between surface and crown fuels (crown base height), and of the wind speed on crown fire...

  7. Community Health Aides in Grenada: A Proposed Experimental Training Model.

    ERIC Educational Resources Information Center

    Kaur, Manjit; Mayfield, James B.

    1994-01-01

    Key factors of a model for training community health aides are (1) extended time for updating and reinforcing skills; (2) relevance to local situations; (3) group process and interpersonal communication training; (4) practical materials; and (5) participation of physicians, local health workers, and community leaders in rural health policy…

  8. Diagnostic modeling of the ARM experimental configuration. Final report

    SciTech Connect

    Somerville, R.C.J.

    1998-04-01

    A major accomplishment of this work was to demonstrate the viability of using in-situ data in both mid-continent North America (SGP CART site) and Tropical Western Pacific (TOGA-COARE) locations to provide the horizontal advective flux convergences which force and constrain the Single-Column Model (SCM) which was the main theoretical tool of this work. The author has used TOGA-COARE as a prototype for the ARM TWP site. Results show that SCMs can produce realistic budgets over the ARM sites without relying on parameterization-dependent operational numerical weather prediction objective analyses. The single-column model is diagnostic rather than prognostic. It is numerically integrated in time as an initial value problem which is forced and constrained by observational data. The input is an observed initial state, plus observationally derived estimates of the time-dependent advection terms in the conservation equations, provided at all model layers. Its output is a complete heat and water budget, including temperature and moisture profiles, clouds and their radiative properties, diabatic heating terms, surface energy balance components, and hydrologic cycle elements, all specified as functions of time. These SCM results should be interpreted in light of the original motivation and purpose of ARM and its goal to improve the treatment of cloud-radiation interactions in climate models.

  9. Attachment Working Models as Unconscious Structures: An Experimental Test

    ERIC Educational Resources Information Center

    Maier, Markus A.; Bernier, Annie; Pekrun, Reinhard; Zimmermann, Peter; Grossmann, Klaus E.

    2004-01-01

    Internal working models of attachment (IWMs) are presumed to be largely "unconscious" representations of childhood attachment experiences. Several instruments have been developed to assess IWMs; some of them are based on self-report and others on narrative interview techniques. This study investigated the capacity of a self-report measure, the…

  10. Experimentally validated thermal model of thin film NiTi

    NASA Astrophysics Data System (ADS)

    Favelukis, Jenna E.; Lavine, Adrienne S.; Carman, Gregory P.

    1999-06-01

    The primary focus of this work is to develop a new analytical approach for thermal modeling of Nickel Titanium (NiTi) shape memory alloy membranes undergoing both phase transformation and large deflections. This paper describes a thermal model of a NiTi plate or thin film, including all the modes of heat loss and latent heat dissipation during the phase transformation. This model is used to predict the NiTi temperature during cooling. The results are compared with experiments conducted on a NiTi plate and thin film (3 micrometers thick), and very good agreement is found. The thermal model is also used to predict the temperature response of a bubble actuator proposed for use in a forced flow environment. Using a 3 mm diameter, 3 micrometers thickness bubble under forced airflow conditions it is possible to achieve a frequency response faster than 300 Hz. Additional calculations were made to verify the structural stability of the actuator system. Predictions indicated that for specific geometries a pressure of at least 35 kPa can be supported by the NiTi membrane. Deflections of a bubble actuator are shown to be on the order of 10% of its diameter while the strain remains below 4%.

  11. Theoretical modeling and experimental analyses of laminated wood composite poles

    Treesearch

    Cheng Piao; Todd F. Shupe; Vijaya Gopu; Chung Y. Hse

    2005-01-01

    Wood laminated composite poles consist of trapezoid-shaped wood strips bonded with synthetic resin. The thick-walled hollow poles had adequate strength and stiffness properties and were a promising substitute for solid wood poles. It was necessary to develop theoretical models to facilitate the manufacture and future installation and maintenance of this novel...

  12. Podocyte Injury and Albuminuria in Experimental Hyperuricemic Model Rats

    PubMed Central

    Asakawa, Shinichiro; Morimoto, Chikayuki; Shiraishi, Takeshi; Nakamura, Takashi; Tamura, Yoshifuru; Kumagai, Takanori; Hosoyamada, Makoto

    2017-01-01

    Although hyperuricemia is shown to accelerate chronic kidney disease, the mechanisms remain unclear. Accumulating studies also indicate that uric acid has both pro- and antioxidant properties. We postulated that hyperuricemia impairs the function of glomerular podocytes, resulting in albuminuria. Hyperuricemic model was induced by oral administration of 2% oxonic acid, a uricase inhibitor. Oxonic acid caused a twofold increase in serum uric acid levels at 8 weeks when compared to control animals. Hyperuricemia in this model was associated with the increase in blood pressure and the wall-thickening of afferent arterioles as well as arcuate arteries. Notably, hyperuricemic rats showed significant albuminuria, and the podocyte injury marker, desmin, was upregulated in the glomeruli. Conversely, podocin, the key component of podocyte slit diaphragm, was downregulated. Structural analysis using transmission electron microscopy confirmed podocyte injury in this model. We found that urinary 8-hydroxy-2′-deoxyguanosine levels were significantly increased and correlated with albuminuria and podocytopathy. Interestingly, although the superoxide dismutase mimetic, tempol, ameliorated the vascular changes and the hypertension, it failed to reduce albuminuria, suggesting that vascular remodeling and podocyte injury in this model are mediated through different mechanisms. In conclusion, vasculopathy and podocytopathy may distinctly contribute to the kidney injury in a hyperuricemic state. PMID:28337250

  13. Assessing analgesic actions of opioids by experimental pain models in healthy volunteers – an updated review

    PubMed Central

    Staahl, Camilla; Olesen, Anne Estrup; Andresen, Trine; Arendt-Nielsen, Lars; Drewes, Asbjørn Mohr

    2009-01-01

    AIM Experimental pain models may help to evaluate the mechanisms of action of analgesics and target the clinical indications for their use. This review addresses how the efficacy of opioids can be assessed in human volunteers using experimental pain models. The drawback with the different study designs is also discussed. METHOD A literature search was completed for randomized controlled studies which included human experimental pain models, healthy volunteers and opioids. RESULTS Opioids with a strong affinity for the µ-opioid receptor decreased the sensation in a variety of experimental pain modalities, but strong tonic pain was attenuated more than short lasting pain and non-painful sensations. The effects of opioids with weaker affinity for the µ-opioid receptor were detected by a more narrow range of pain models, and the assessment methods needed to be more sensitive. CONCLUSION The way the pain is induced, assessed and summarized is very important for the sensitivity of the pain models. This review gives an overview of how different opioids perform in experimental pain models. Generally experimental pain models need to be designed with careful consideration of pharmacological mechanisms and pharmacokinetics of analgesics. This knowledge can aid the decisions needed to be taken when designing experimental pain studies for compounds entering phase 1 clinical trials. PMID:19694733

  14. Rush immunotherapy in an experimental model of feline allergic asthma.

    PubMed

    Reinero, Carol R; Byerly, Jenni R; Berghaus, Roy D; Berghaus, Londa J; Schelegle, Edward S; Hyde, Dallas M; Gershwin, Laurel J

    2006-03-15

    Specific allergen immunotherapy represents the only curative treatment of allergy. No studies have evaluated its efficacy in feline allergic asthma. We hypothesized that an abbreviated course of immunotherapy (rush immunotherapy, RIT) would blunt eosinophilic airways inflammation in experimental feline asthma induced with Bermuda grass allergen (BGA). The 6-month study included asthmatic-RIT treated cats; asthmatic-no RIT treated cats; and non-asthmatic cats. RIT involved increasing parenteral doses (20-200 microg) of BGA over 2 days. Numbers of eosinophils in bronchoalveolar lavage fluid (BALF), serum and BALF immunoglobulins, lymphocyte blastogenesis assays, and cytokines in blood and BALF were evaluated. BALF eosinophils decreased (P=0.048) only in asthmatic-RIT treated cats (baseline 1.1 x 10(6); Month 6, 2.4 x 10(5)). Serum BGA-specific IgG was higher (P<0.001) at all time points after baseline within the asthmatic-RIT group, and was higher (P<0.001) than asthmatic-no RIT cats at Months 1 and 3. No differences (P=0.133) in BGA-specific IgE levels over time were noted among asthmatic-RIT cats, but this group had lower IgE levels (P<0.001) levels than asthmatic no-RIT cats at Months 3 and 6. Differences in BGA-specific IgA levels over time and between the two groups did not reach the traditional level of significance. The mean BGA stimulation index in the asthmatic-RIT cats was biologically insignificant at 6 months, reflecting BGA-specific lymphocyte hypoproliferation. Preliminary results of cytokine profiles were not significantly different; however, BAL cytokine profiles favoring a Th2 response prior to RIT shifted to increased IFN-g and IL-10 thereafter. RIT dampens eosinophilic airways inflammation in cats with experimental asthma. The mechanism of RIT may involve changes in allergen-specific immunoglobulins, induction of hyporesponsive lymphocytes, or alteration of cytokine profiles.

  15. Quantitative experimental modelling of fragmentation during explosive volcanism

    NASA Astrophysics Data System (ADS)

    Thordén Haug, Ø.; Galland, O.; Gisler, G.

    2012-04-01

    Phreatomagmatic eruptions results from the violent interaction between magma and an external source of water, such as ground water or a lake. This interaction causes fragmentation of the magma and/or the host rock, resulting in coarse-grained (lapilli) to very fine-grained (ash) material. The products of phreatomagmatic explosions are classically described by their fragment size distribution, which commonly follows power laws of exponent D. Such descriptive approach, however, considers the final products only and do not provide information on the dynamics of fragmentation. The aim of this contribution is thus to address the following fundamental questions. What are the physics that govern fragmentation processes? How fragmentation occurs through time? What are the mechanisms that produce power law fragment size distributions? And what are the scaling laws that control the exponent D? To address these questions, we performed a quantitative experimental study. The setup consists of a Hele-Shaw cell filled with a layer of cohesive silica flour, at the base of which a pulse of pressurized air is injected, leading to fragmentation of the layer of flour. The fragmentation process is monitored through time using a high-speed camera. By varying systematically the air pressure (P) and the thickness of the flour layer (h) we observed two morphologies of fragmentation: "lift off" where the silica flour above the injection inlet is ejected upwards, and "channeling" where the air pierces through the layer along sub-vertical conduit. By building a phase diagram, we show that the morphology is controlled by P/dgh, where d is the density of the flour and g is the gravitational acceleration. To quantify the fragmentation process, we developed a Matlab image analysis program, which calculates the number and sizes of the fragments, and so the fragment size distribution, during the experiments. The fragment size distributions are in general described by power law distributions of

  16. Experimental observations and theoretical models for beam-beam phenomena

    SciTech Connect

    Kheifets, S.

    1981-03-01

    The beam-beam interaction in storage rings exhibits all the characteristics of nonintegrable dynamical systems. Here one finds all kinds of resonances, closed orbits, stable and unstable fixed points, stochastic layers, chaotic behavior, diffusion, etc. The storage ring itself being an expensive device nevertheless while constructed and put into operation presents a good opportunity of experimentally studying the long-time behavior of both conservative (proton machines) and nonconservative (electron machines) dynamical systems - the number of bunch-bunch interactions routinely reaches values of 10/sup 10/-10/sup 11/ and could be increased by decreasing the beam current. At the same time the beam-beam interaction puts practical limits for the yield of the storage ring. This phenomenon not only determines the design value of main storage ring parameters (luminosity, space charge parameters, beam current), but also in fact prevents many of the existing storage rings from achieving design parameters. Hence, the problem has great practical importance along with its enormous theoretical interest. A brief overview of the problem is presented.

  17. Modeling of rock friction 1. Experimental results and constitutive equations

    USGS Publications Warehouse

    Dieterich, J.H.

    1979-01-01

    Direct shear experiments on ground surfaces of a granodiorite from Raymond, California, at normal stresses of ??6 MPa demonstrate that competing time, displacement, and velocity effects control rock friction. It is proposed that the strength of the population of points of contacts between sliding surfaces determines frictional strength and that the population of contacts changes continuously with displacements. Previous experiments demonstrate that the strength of the contacts increases with the age of the contacts. The present experiments establish that a characteristic displacement, proportional to surface roughness, is required to change the population of contacts. Hence during slip the average age of the points of contact and therefore frictional strength decrease as slip velocity increases. Displacement weakening and consequently the potential for unstable slip occur whenever displacement reduces the average age of the contacts. In addition to this velocity dependency, which arises from displacement dependency and time dependency, the experiments also show a competing but transient increase in friction whenever slip velocity increases. Creep of the sliding surface at stresses below that for steady state slip is also observed. Constitutive relationships are developed that permit quantitative simulation of the friction versus displacement data as a function of surface roughness and for different time and velocity histories. Unstable slip in experiments is controlled by these constitutive effects and by the stiffness of the experimental system. It is argued that analogous properties control earthquake instability. Copyright ?? 1979 by the American Geophysical Union.

  18. Formulation of an experimental substructure model using a Craig-Bampton based transmission simulator

    NASA Astrophysics Data System (ADS)

    Kammer, Daniel C.; Allen, Mathew S.; Mayes, Randy L.

    2015-12-01

    Experimental-analytical substructuring is attractive when there is motivation to replace one or more system subcomponents with an experimental model. This experimentally derived substructure can then be coupled to finite element models of the rest of the structure to predict the system response. The transmission simulator method couples a fixture to the component of interest during a vibration test in order to improve the experimental model for the component. The transmission simulator is then subtracted from the tested system to produce the experimental component. The method reduces ill-conditioning by imposing a least squares fit of constraints between substructure modal coordinates to connect substructures, instead of directly connecting physical interface degrees of freedom. This paper presents an alternative means of deriving the experimental substructure model, in which a Craig-Bampton representation of the transmission simulator is created and subtracted from the experimental measurements. The corresponding modal basis of the transmission simulator is described by the fixed-interface modes, rather than free modes that were used in the original approach. These modes do a better job of representing the shape of the transmission simulator as it responds within the experimental system, leading to more accurate results using fewer modes. The new approach is demonstrated using a simple finite element model based example with a redundant interface.

  19. First principles Candu fuel model and validation experimentation

    SciTech Connect

    Corcoran, E.C.; Kaye, M.H.; Lewis, B.J.; Thompson, W.T.; Akbari, F.; Higgs, J.D.; Verrall, R.A.; He, Z.; Mouris, J.F.

    2007-07-01

    Many modeling projects on nuclear fuel rest on a quantitative understanding of the co-existing phases at various stages of burnup. Since the various fission products have considerably different abilities to chemically associate with oxygen, and the O/M ratio is slowly changing as well, the chemical potential (generally expressed as an equivalent oxygen partial pressure) is a function of burnup. Concurrently, well-recognized small fractions of new phases such as inert gas, noble metals, zirconates, etc. also develop. To further complicate matters, the dominant UO{sub 2} fuel phase may be non-stoichiometric and most of minor phases have a variable composition dependent on temperature and possible contact with the coolant in the event of a sheathing defect. A Thermodynamic Fuel Model to predict the phases in partially burned Candu nuclear fuel containing many major fission products has been under development. This model is capable of handling non-stoichiometry in the UO{sub 2} fluorite phase, dilute solution behaviour of significant solute oxides, noble metal inclusions, a second metal solid solution U(Pd-Rh-Ru)3, zirconate and uranate solutions as well as other minor solid phases, and volatile gaseous species. The treatment is a melding of several thermodynamic modeling projects dealing with isolated aspects of this important multi-component system. To simplify the computations, the number of elements has been limited to twenty major representative fission products known to appear in spent fuel. The proportion of elements must first be generated using SCALES-5. Oxygen is inferred from the concentration of the other elements. Provision to study the disposition of very minor fission products is included within the general treatment but these are introduced only on an as needed basis for a particular purpose. The building blocks of the model are the standard Gibbs energies of formation of the many possible compounds expressed as a function of temperature. To these data

  20. Impact Flash Physics: Modeling and Comparisons With Experimental Results

    NASA Astrophysics Data System (ADS)

    Rainey, E.; Stickle, A. M.; Ernst, C. M.; Schultz, P. H.; Mehta, N. L.; Brown, R. C.; Swaminathan, P. K.; Michaelis, C. H.; Erlandson, R. E.

    2015-12-01

    Hypervelocity impacts frequently generate an observable "flash" of light with two components: a short-duration spike due to emissions from vaporized material, and a long-duration peak due to thermal emissions from expanding hot debris. The intensity and duration of these peaks depend on the impact velocity, angle, and the target and projectile mass and composition. Thus remote sensing measurements of planetary impact flashes have the potential to constrain the properties of impacting meteors and improve our understanding of impact flux and cratering processes. Interpreting impact flash measurements requires a thorough understanding of how flash characteristics correlate with impact conditions. Because planetary-scale impacts cannot be replicated in the laboratory, numerical simulations are needed to provide this insight for the solar system. Computational hydrocodes can produce detailed simulations of the impact process, but they lack the radiation physics required to model the optical flash. The Johns Hopkins University Applied Physics Laboratory (APL) developed a model to calculate the optical signature from the hot debris cloud produced by an impact. While the phenomenology of the optical signature is understood, the details required to accurately model it are complicated by uncertainties in material and optical properties and the simplifications required to numerically model radiation from large-scale impacts. Comparisons with laboratory impact experiments allow us to validate our approach and to draw insight regarding processes that occur at all scales in impact events, such as melt generation. We used Sandia National Lab's CTH shock physics hydrocode along with the optical signature model developed at APL to compare with a series of laboratory experiments conducted at the NASA Ames Vertical Gun Range. The experiments used Pyrex projectiles to impact pumice powder targets with velocities ranging from 1 to 6 km/s at angles of 30 and 90 degrees with respect to

  1. Experimental evaluation of the power balance model of speed skating.

    PubMed

    de Koning, Jos J; Foster, Carl; Lampen, Joanne; Hettinga, Floor; Bobbert, Maarten F

    2005-01-01

    Prediction of speed skating performance with a power balance model requires assumptions about the kinetics of energy production, skating efficiency, and skating technique. The purpose of this study was to evaluate these parameters during competitive imitations for the purpose of improving model predictions. Elite speed skaters (n = 8) performed races and submaximal efficiency tests. External power output (P(o)) was calculated from movement analysis and aerodynamic models and ice friction measurements. Aerobic kinetics was calculated from breath-by-breath oxygen uptake (Vo(2)). Aerobic power (P(aer)) was calculated from measured skating efficiency. Anaerobic power (P(an)) kinetics was determined by subtracting P(aer) from P(o). We found gross skating efficiency to be 15.8% (1.8%). In the 1,500-m event, the kinetics of P(an) was characterized by a first-order system as P(an) = 88 + 556e(-0.0494t) (in W, where t is time). The rate constant for the increase in P(aer) was -0.153 s(-1), the time delay was 8.7 s, and the peak P(aer) was 234 W; P(aer) was equal to 234[1 - e(-0.153(t-8.7))] (in W). Skating position changed with preextension knee angle increasing and trunk angle decreasing throughout the event. We concluded the pattern of P(aer) to be quite similar to that reported during other competitive imitations, with the exception that the increase in P(aer) was more rapid. The pattern of P(an) does not appear to fit an "all-out" pattern, with near zero values during the last portion of the event, as assumed in our previous model (De Koning JJ, de Groot G, and van Ingen Schenau GJ. J Biomech 25: 573-580, 1992). Skating position changed in ways different from those assumed in our previous model. In addition to allowing improved predictions, the results demonstrate the importance of observations in unique subjects to the process of model construction.

  2. Experimental Errors in QSAR Modeling Sets: What We Can Do and What We Cannot Do.

    PubMed

    Zhao, Linlin; Wang, Wenyi; Sedykh, Alexander; Zhu, Hao

    2017-06-30

    Numerous chemical data sets have become available for quantitative structure-activity relationship (QSAR) modeling studies. However, the quality of different data sources may be different based on the nature of experimental protocols. Therefore, potential experimental errors in the modeling sets may lead to the development of poor QSAR models and further affect the predictions of new compounds. In this study, we explored the relationship between the ratio of questionable data in the modeling sets, which was obtained by simulating experimental errors, and the QSAR modeling performance. To this end, we used eight data sets (four continuous endpoints and four categorical endpoints) that have been extensively curated both in-house and by our collaborators to create over 1800 various QSAR models. Each data set was duplicated to create several new modeling sets with different ratios of simulated experimental errors (i.e., randomizing the activities of part of the compounds) in the modeling process. A fivefold cross-validation process was used to evaluate the modeling performance, which deteriorates when the ratio of experimental errors increases. All of the resulting models were also used to predict external sets of new compounds, which were excluded at the beginning of the modeling process. The modeling results showed that the compounds with relatively large prediction errors in cross-validation processes are likely to be those with simulated experimental errors. However, after removing a certain number of compounds with large prediction errors in the cross-validation process, the external predictions of new compounds did not show improvement. Our conclusion is that the QSAR predictions, especially consensus predictions, can identify compounds with potential experimental errors. But removing those compounds by the cross-validation procedure is not a reasonable means to improve model predictivity due to overfitting.

  3. Experimental Errors in QSAR Modeling Sets: What We Can Do and What We Cannot Do

    PubMed Central

    2017-01-01

    Numerous chemical data sets have become available for quantitative structure–activity relationship (QSAR) modeling studies. However, the quality of different data sources may be different based on the nature of experimental protocols. Therefore, potential experimental errors in the modeling sets may lead to the development of poor QSAR models and further affect the predictions of new compounds. In this study, we explored the relationship between the ratio of questionable data in the modeling sets, which was obtained by simulating experimental errors, and the QSAR modeling performance. To this end, we used eight data sets (four continuous endpoints and four categorical endpoints) that have been extensively curated both in-house and by our collaborators to create over 1800 various QSAR models. Each data set was duplicated to create several new modeling sets with different ratios of simulated experimental errors (i.e., randomizing the activities of part of the compounds) in the modeling process. A fivefold cross-validation process was used to evaluate the modeling performance, which deteriorates when the ratio of experimental errors increases. All of the resulting models were also used to predict external sets of new compounds, which were excluded at the beginning of the modeling process. The modeling results showed that the compounds with relatively large prediction errors in cross-validation processes are likely to be those with simulated experimental errors. However, after removing a certain number of compounds with large prediction errors in the cross-validation process, the external predictions of new compounds did not show improvement. Our conclusion is that the QSAR predictions, especially consensus predictions, can identify compounds with potential experimental errors. But removing those compounds by the cross-validation procedure is not a reasonable means to improve model predictivity due to overfitting. PMID:28691113

  4. Parametric and non-parametric modeling of short-term synaptic plasticity. Part II: Experimental study.

    PubMed

    Song, Dong; Wang, Zhuo; Marmarelis, Vasilis Z; Berger, Theodore W

    2009-02-01

    This paper presents a synergistic parametric and non-parametric modeling study of short-term plasticity (STP) in the Schaffer collateral to hippocampal CA1 pyramidal neuron (SC) synapse. Parametric models in the form of sets of differential and algebraic equations have been proposed on the basis of the current understanding of biological mechanisms active within the system. Non-parametric Poisson-Volterra models are obtained herein from broadband experimental input-output data. The non-parametric model is shown to provide better prediction of the experimental output than a parametric model with a single set of facilitation/depression (FD) process. The parametric model is then validated in terms of its input-output transformational properties using the non-parametric model since the latter constitutes a canonical and more complete representation of the synaptic nonlinear dynamics. Furthermore, discrepancies between the experimentally-derived non-parametric model and the equivalent non-parametric model of the parametric model suggest the presence of multiple FD processes in the SC synapses. Inclusion of an additional set of FD process in the parametric model makes it replicate better the characteristics of the experimentally-derived non-parametric model. This improved parametric model in turn provides the requisite biological interpretability that the non-parametric model lacks.

  5. Targeting Smoothened Sensitizes Gastric Cancer to Chemotherapy in Experimental Models

    PubMed Central

    Ma, Huifa; Tian, Yongsheng; Yu, Xiangyang

    2017-01-01

    Background The Hedgehog pathway receptor smoothened (SMO) has critical roles in tumor progression. However, whether SMO is a key factor regulating gastric cancer chemotherapy resistance is unknown. Material/Methods We investigated the potential functions of SMO in inducing gastric cancer paclitaxel resistance in clinical samples, gastric cancer cell lines (424GC and AGS), and subcutaneous syngeneic mouse models. Results We found high SMO expression in paclitaxel-resistant gastric cancer clinical samples. Paclitaxel gastric cancer cells had higher SMO expression than in drug-sensitive cells. Upregulating SMO expression induced paclitaxel resistance in gastric cells lines via enhancing cell proliferation and inhibiting apoptosis. The combination of IPI-926, an inhibitor of SMO, with paclitaxel decreased cell viability of paclitaxel-resistant gastric cancer cells in vitro and controlled tumor growth in animal models. Conclusions The Hedgehog pathway receptor SMO is an important regulator of gastric cancer paclitaxel resistance and could be a target for sensitizing paclitaxel-resistant tumors. PMID:28350784

  6. Experimental models of bone and prosthetic joint infections.

    PubMed

    Crémieux, A C; Carbon, C

    1997-12-01

    Bone and joint infections are difficult to cure. The difficulty is related to the presence of bacteria adherent to foreign material in many cases and also to the limited activity of antibiotics in infected bones. Clinical trials are difficult to design because of the heterogeneity of the disease and the number of factors that could influence the therapeutic response. To control for these multiple variables, attempts have been made to develop reliable animal models of osteomyelitis and prosthetic joint infections that closely mimic the different infections seen in orthopedic surgery and that allow evaluation of the efficacy of surgical procedures as well as local or systemic antibiotic therapy. These models will continue to provide us information on the pathogenesis and management of such infections.

  7. [Experimental evaluation of the spraying disinfection efficiency on dental models].

    PubMed

    Zhang, Yi; Fu, Yuan-fei; Xu, Kan

    2013-08-01

    To evaluate the disinfect effect after spraying a new kind of disinfectant on the dental plaster models. The germ-free plaster samples, which were smeared with bacteria compound including Staphylococcus aureus, Escherichia coli, Saccharomyces albicans, Streptococcus mutans and Actinomyces viscosus were sprayed with disinfectants (CaviCide) and glutaraldehyde individually. In one group(5 minutes later) and another group(15 minutes later), the colonies were counted for statistical analysis after sampling, inoculating, and culturing which were used for evaluation of disinfecting efficiency. ANOVA was performed using SPSS12.0 software package. All sample bacteria were eradicated after spraying disinfectants(CaviCide) within 5 minutes and effective bacteria control was retained after 15 minutes. There was significant difference between the disinfecting efficiency of CaviCide and glutaraldehyde. The effect of disinfection with spraying disinfectants (CaviCide) on dental models is quick and effective.

  8. EXPERIMENTAL MODEL OF ALCOHOL-RELATED PERIPHERAL NEUROPATHY

    PubMed Central

    MELLION, MICHELLE L.; NGUYEN, VANANH; TONG, MING; GILCHRIST, JAMES; DE LA MONTE, SUZANNE

    2015-01-01

    Introduction The aim of this work was to determine the effect of chronic alcohol exposure on peripheral nerves in a nutritionally balanced rat model of alcoholism. Methods Three different strains of adult male rats were pair-fed for 8 weeks with isocaloric liquid diets containing 0% or 37% ethanol. Nerve conduction studies (NCS) were performed. Peripheral nerve and muscle were examined histologically with morphometrics. Results Ethanol exposure significantly slowed velocity in tibial and fibular nerves, but not in the plantar nerve in all 3 strains. Studies of the sciatic nerve revealed decreased fiber diameters and increased regenerative sprouts in peripheral nerves. There was muscle denervation of ethanol-exposed rats in all 3 strains. Conclusions Chronic ethanol exposure caused a polyneuropathy characterized by axonal degeneration despite adequate nutrition. These results suggest that ethanol exposure has direct neurotoxic effects on peripheral nerves. This model may be useful in understanding the underlying mechanism(s) of alcohol-related peripheral neuropathy. PMID:23761140

  9. Experimental autoimmune myocarditis: a suitable model to study neuroimmune crosstalk.

    PubMed

    Leiros, C P; Sterin-Borda, L; Goren, N; Borda, E S

    1995-01-01

    This review regards the main functional characteristics of hearts subjected to an autoimmune response, focusing especially on the role of T lymphocytes and autoantibodies in the development of cardiac dysfunction. Evidence of a strong association in the onset and time-course of immune response and cardiac dysfunction is presented and the results are viewed comparatively with myocarditis models induced by heart, parasite or virus inoculation. Cardiac damage is evaluated regarding various aspects, namely histologic, immunologic, biochemical, pharmacologic, physiologic. Finally, the model, for its characteristics of resulting from an autoimmune response against the heart with functional consequences, has proved its usefulness to study neuroimmune interaction, mainly the immune to nervous direction, as autoantibodies and T cell-derived factors have a role in cardiac failure.

  10. Experimental exploration of diffusion panel labyrinth in scale model

    NASA Astrophysics Data System (ADS)

    Vance, Mandi M.

    Small rehearsal and performance venues often lack the rich reverberation found in larger spaces. Higini Arau-Puchades has designed and implemented a system of diffusion panels in the Orchestra Rehearsal Room at the Great Theatre Liceu and the Tonhalle St. Gallen that lengthen the reverberation time. These panels defy traditional room acoustics theory which holds that adding material to a room will shorten the reverberation time. This work explores several versions of Arau-Puchades' panels and room characteristics in scale model. Reverberation times are taken from room impulse response measurements in order to better understand the unusual phenomenon. Scale modeling enables many tests but has limitations in its accuracy due to the higher frequency range involved. Further investigations are necessary to establish how the sound energy interacts with the diffusion panels and confirm their validity in a range of applications.

  11. Traumatic Coagulopathy: Where are the Good Experimental Models?

    DTIC Science & Technology

    2008-10-01

    not relevant after detailed review (grade D). Results: This structured literature review demonstrated a lack of relevant models for human traumatic...need to more closely resemble human physiology and real-life conditions if they are to influence clinical practice. Key Words: Coagulopathy, Trauma...Publications describing experiments in human sub- jects were also excluded from this review. An internal valid- ity assessment of the risk of selection

  12. Neurobehavioral effects of liraglutide and sitagliptin in experimental models.

    PubMed

    Kamble, Mayur; Gupta, Rachna; Rehan, Harmeet S; Gupta, Lalit K

    2016-03-05

    Glucagon-like peptide (GLP-1) receptor agonists and dipeptidyl peptidase 4 (DPP-4) inhibitors are two currently approved therapies for type 2 diabetes mellitus (T2DM). Present study evaluated the effect of liraglutide (a long-acting GLP-1 agonist) and sitagliptin (a DPP-4 inhibitor) on nociception, anxiety, depression-like behavior and cognition in rats or mice. Nociception was assessed using tail-flick test; anxiety-behavior in open-field test and elevated plus maze (EPM) test while depression-like behavior was evaluated in forced swim test (FST) and tail-suspension test (TST). Cognition was assessed in EPM and Morris water maze (MWM) following memory deficit induced by pentylenetetrazole (PTZ) or scopolamine. In tail-flick test sitagliptin (6 mg/kg) produced transient nociceptive effect. Liraglutide (200 µg/kg) reduced peripheral square crossings by rats in open field test as well as reduced closed arm entries in the EPM, indicating a decline in exploratory behavior. In FST and TST models for depression, the duration of immobility with sitagliptin (6 mg/kg) was reduced significantly in comparison to control group suggesting its antidepressant effect. Liraglutide did not show any antidepressant action. In EPM test for cognition, liraglutide and sitagliptin ameliorated the increase in transfer latency caused by PTZ in a dose-dependent manner. In MWM liraglutide and sitagliptin prevented the scopolamine-induced increase of the escape latency. This study shows that sitagliptin has mild antinociceptive effect and anti-depressant effect in the animal models of depression while liraglutide did not have such an effect. Liraglutide showed anxiogenic effects in the animal models. Both liraglutide and sitagliptin produced cognitive improvement in the animal models.

  13. Comparative study of flavonoids in experimental models of inflammation.

    PubMed

    Rotelli, Alejandra Ester; Guardia, Teresita; Juárez, Américo Osvaldo; de la Rocha, Nadir Ernesto; Pelzer, Lilian Eugenia

    2003-12-01

    The anti-inflammatory activities of flavonols (quercetin, rutin and morin) and flavanones (hesperetin and hesperidin) were investigated in animal models of acute and chronic inflammation. Rutin was only effective in the chronic process, principally in adjuvant arthritis. On neurogenic inflammation induced by xylene, only the flavanones were effective; besides, these compounds were the most effective on subchronic process. The most important compound in reducing paw oedema induced by carrageenan was quercetin.

  14. Experimental Research on Rail Vehicle Safety Using Dynamically Scaled Models.

    DTIC Science & Technology

    1976-01-01

    June 28, 1977) includes: (1) the design and fabrication of a scale model track, single wheelset , test carriage, and associated instrumentation; (2...measurement of wheelset displacement-force characteristics at steady velocity; (3) measurements of wheel-climb phenomenon; and (4) comparison of...34V* d) Detailed design of wheelset , idler carriage, linkage, and instrumen- tation systems. The linkage system, shown schematically in Figure :mi

  15. Experimental Benchmarking of Fire Modeling Simulations. Final Report

    SciTech Connect

    Greiner, Miles; Lopez, Carlos

    2003-10-08

    A series of large-scale fire tests were performed at Sandia National Laboratories to simulate a nuclear waste transport package under severe accident conditions. The test data were used to benchmark and adjust the Container Analysis Fire Environment (CAFE) computer code. CAFE is a computational fluid dynamics fire model that accurately calculates the heat transfer from a large fire to a massive engulfed transport package. CAFE will be used in transport package design studies and risk analyses.

  16. Comparison of Hall Thruster Plume Expansion Model with Experimental Data

    DTIC Science & Technology

    2006-05-23

    focus of this study, is a hybrid particle- in-cell ( PIC ) model that tracks particles along an unstructured tetrahedral mesh. * Research Engineer...measurements of the ion current density profile, ion energy distributions, and ion species fraction distributions using a nude Faraday probe, retarding...Vol.37 No.1. 6 Oh, D. and Hastings, D., “Three Dimensional PIC -DSMC Simulations of Hall Thruster Plumes and Analysis for Realistic Spacecraft

  17. Circulation Control Model Experimental Database for CFD Validation

    NASA Technical Reports Server (NTRS)

    Paschal, Keith B.; Neuhart, Danny H.; Beeler, George B.; Allan, Brian G.

    2012-01-01

    A 2D circulation control wing was tested in the Basic Aerodynamic Research Tunnel at the NASA Langley Research Center. A traditional circulation control wing employs tangential blowing along the span over a trailing-edge Coanda surface for the purpose of lift augmentation. This model has been tested extensively at the Georgia Tech Research Institute for the purpose of performance documentation at various blowing rates. The current study seeks to expand on the previous work by documenting additional flow-field data needed for validation of computational fluid dynamics. Two jet momentum coefficients were tested during this entry: 0.047 and 0.114. Boundary-layer transition was investigated and turbulent boundary layers were established on both the upper and lower surfaces of the model. Chordwise and spanwise pressure measurements were made, and tunnel sidewall pressure footprints were documented. Laser Doppler Velocimetry measurements were made on both the upper and lower surface of the model at two chordwise locations (x/c = 0.8 and 0.9) to document the state of the boundary layers near the spanwise blowing slot.

  18. Microbial dormancy improves development and experimental validation of ecosystem model

    SciTech Connect

    Wang, Gangsheng; Jagadamma, Sindhu; Mayes, Melanie; Schadt, Christopher Warren; Steinweg, Jessica M.; Gu, Lianhong; Post, Wilfred M.

    2014-07-11

    Climate feedbacks from soils can result from environmental change followed by response of plant and microbial communities, and/or associated changes in nutrient cycling. Explicit consideration of microbial life history traits and functions may be necessary to predict climate feedbacks due to changes in the physiology and community composition of microbes and their associated effect on carbon cycling. Here, we enhanced the Microbial-Enzyme-mediated Decomposition (MEND) model by incorporating microbial dormancy and the ability to track multiple isotopes of carbon. We tested two versions of MEND, i.e., MEND with dormancy and MEND without dormancy, against long-term (270 d) lab incubations of four soils with isotopically-labeled substrates. MEND without dormancy adequately fitted multiple observations (total and 14C respiration, and dissolved organic carbon), but at the cost of significantly underestimating the total microbial biomass. The MEND with dormancy improved estimates of microbial biomass by 20 71% over the MEND without dormancy. We observed large differences for two fitted model parameters, the specific maintenance and growth rates for active microbes, depending on whether dormancy was considered. Together our model extrapolations of the incubation study show that long-term soil incubations with observations in multiple carbon pools are necessary to estimate both decomposition and microbial parameters. These efforts should provide essential support to future field- and global-scale simulations and enable more confident predictions of feedbacks between environmental change and carbon cycling.

  19. Microbial dormancy improves development and experimental validation of ecosystem model

    DOE PAGES

    Wang, Gangsheng; Jagadamma, Sindhu; Mayes, Melanie; ...

    2014-07-11

    Climate feedbacks from soils can result from environmental change followed by response of plant and microbial communities, and/or associated changes in nutrient cycling. Explicit consideration of microbial life history traits and functions may be necessary to predict climate feedbacks due to changes in the physiology and community composition of microbes and their associated effect on carbon cycling. Here, we enhanced the Microbial-Enzyme-mediated Decomposition (MEND) model by incorporating microbial dormancy and the ability to track multiple isotopes of carbon. We tested two versions of MEND, i.e., MEND with dormancy and MEND without dormancy, against long-term (270 d) lab incubations of fourmore » soils with isotopically-labeled substrates. MEND without dormancy adequately fitted multiple observations (total and 14C respiration, and dissolved organic carbon), but at the cost of significantly underestimating the total microbial biomass. The MEND with dormancy improved estimates of microbial biomass by 20 71% over the MEND without dormancy. We observed large differences for two fitted model parameters, the specific maintenance and growth rates for active microbes, depending on whether dormancy was considered. Together our model extrapolations of the incubation study show that long-term soil incubations with observations in multiple carbon pools are necessary to estimate both decomposition and microbial parameters. These efforts should provide essential support to future field- and global-scale simulations and enable more confident predictions of feedbacks between environmental change and carbon cycling.« less

  20. Hyperthyroid monkeys: a nonhuman primate model of experimental Graves' disease.

    PubMed

    Wang, Y; Wu, L P; Fu, J; Lv, H J; Guan, X Y; Xu, L; Chen, P; Gao, C Q; Hou, P; Ji, M J; Shi, B Y

    2013-12-01

    Graves' disease (GD) is a common organ-specific autoimmune disease with the prevalence between 0.5 and 2% in women. Several lines of evidence indicate that the shed A-subunit rather than the full-length thyrotropin receptor (TSHR) is the autoantigen that triggers autoimmunity and leads to hyperthyroidism. We have for the first time induced GD in female rhesus monkeys, which exhibit greater similarity to patients with GD than previous rodent models. After final immunization, the monkeys injected with adenovirus expressing the A-subunit of TSHR (A-sub-Ad) showed some characteristics of GD. When compared with controls, all the test monkeys had significantly higher TSHR antibody levels, half of them had increased total thyroxine (T₄) and free T₄, and 50% developed goiter. To better understand the underlying mechanisms, quantitative studies on subpopulations of CD4+T helper cells were carried out. The data indicated that this GD model involved a mixed Th1 and Th2 response. Declined Treg proportions and increased Th17:Treg ratio are also observed. Our rhesus monkey model successfully mimicked GD in humans in many aspects. It would be a useful tool for furthering our understanding of the pathogenesis of GD and would potentially shorten the distance toward the prevention and treatment of this disease in human.

  1. Experimental model of human corpus cavernosum smooth muscle relaxation.

    PubMed

    Regadas, Rommel P; Moraes, Maria E A; Mesquita, Francisco J C; Cerqueira, Joao B G; Gonzaga-Silva, Lucio F

    2010-01-01

    To describe a technique for en bloc harvesting of the corpus cavernosum, cavernous artery and urethra from transplant organ donors and contraction-relaxation experiments with corpus cavernosum smooth muscle. The corpus cavernosum was dissected to the point of attachment with the crus penis. A 3 cm segment (corpus cavernosum and urethra) was isolated and placed in ice-cold sterile transportation buffer. Under magnification, the cavernous artery was dissected. Thus, 2 cm fragments of cavernous artery and corpus cavernosum were obtained. Strips measuring 3 x 3 x 8 mm(3) were then mounted vertically in an isolated organ bath device. Contractions were measured isometrically with a Narco-Biosystems force displacement transducer (model F-60, Narco-Biosystems, Houston, TX, USA) and recorded on a 4-channel Narco-Biosystems desk model polygraph. Phenylephrine (1 microM) was used to induce tonic contractions in the corpus cavernosum (3-5 g tension) and cavernous artery (0.5-1 g tension) until reaching a plateau. After precontraction, smooth muscle relaxants were used to produce relaxation-response curves (10(-12) M to 10(-4) M). Sodium nitroprusside was used as a relaxation control. The harvesting technique and the smooth muscle contraction-relaxation model described in this study were shown to be useful instruments in the search for new drugs for the treatment of human erectile dysfunction.

  2. Experimental performance evaluation of human balance control models.

    PubMed

    Huryn, Thomas P; Blouin, Jean-Sébastien; Croft, Elizabeth A; Koehle, Michael S; Van der Loos, H F Machiel

    2014-11-01

    Two factors commonly differentiate proposed balance control models for quiet human standing: 1) intermittent muscle activation and 2) prediction that overcomes sensorimotor time delays. In this experiment we assessed the viability and performance of intermittent activation and prediction in a balance control loop that included the neuromuscular dynamics of human calf muscles. Muscles were driven by functional electrical stimulation (FES). The performance of the different controllers was compared based on sway patterns and mechanical effort required to balance a human body load on a robotic balance simulator. All evaluated controllers balanced subjects with and without a neural block applied to their common peroneal and tibial nerves, showing that the models can produce stable balance in the absence of natural activation. Intermittent activation required less stimulation energy than continuous control but predisposed the system to increased sway. Relative to intermittent control, continuous control reproduced the sway size of natural standing better. Prediction was not necessary for stable balance control but did improve stability when control was intermittent, suggesting a possible benefit of a predictor for intermittent activation. Further application of intermittent activation and predictive control models may drive prolonged, stable FES-controlled standing that improves quality of life for people with balance impairments.

  3. Beyond discounting: possible experimental models of impulse control.

    PubMed

    Monterosso, J; Ainslie, G

    1999-10-01

    Animal studies of impulsivity have typically used one of three models: a delay of reward procedure, a differential reinforcement for low rate responding (DRL) procedure, or an autoshaping procedure. In each of these paradigms, we argue, measurement of impulsivity is implicitly or explicitly equated with the effect delay has on the value of reward. The steepness by which delay diminishes value (the temporal discount function) is treated as an index of impulsivity. In order to provide a better analog of human impulsivity, this model needs to be expanded to include the converse of impulsivity - self-control. Through mechanisms such as committing to long range interests before the onset of temptation, or through bundling individual choices into classes of choices that are made at once, human decision-making can often look far less myopic than single trial experiments predict. For people, impulsive behavior may be more often the result of the breakdown of self-control mechanisms than of steep discount functions. Existing animal models of self-control are discussed, and future directions are suggested for psychopharmacological research.

  4. Mesenchymal stem cells in the treatment of inflammatory and autoimmune diseases in experimental animal models

    PubMed Central

    Klinker, Matthew W; Wei, Cheng-Hong

    2015-01-01

    Multipotent mesenchymal stromal cells [also known as mesenchymal stem cells (MSCs)] are currently being studied as a cell-based treatment for inflammatory disorders. Experimental animal models of human immune-mediated diseases have been instrumental in establishing their immunosuppressive properties. In this review, we summarize recent studies examining the effectiveness of MSCs as immunotherapy in several widely-studied animal models, including type 1 diabetes, experimental autoimmune arthritis, experimental autoimmune encephalomyelitis, inflammatory bowel disease, graft-vs-host disease, and systemic lupus erythematosus. In addition, we discuss mechanisms identified by which MSCs mediate immune suppression in specific disease models, and potential sources of functional variability of MSCs between studies. PMID:25914763

  5. Cleavage pattern of DNA caused by endonuclease: Theoretical modeling and experimental verification

    NASA Astrophysics Data System (ADS)

    Inagaki, Shio; Liu, Li; Takinoue, Masahiro; Yoshikawa, Kenichi

    2010-02-01

    In apoptotic cells, genomic DNA molecules are fragmented into multiple fragments with lengths that are integer multiples of approximately 180-200 base pairs (bp), i.e., the size of a single nucleosome. Here we propose a simple mathematical model for interpreting this cleavage pattern of DNA. Under the condition of a purely stochastic cleavage process, we derive a time evolution of the probability distribution of the fragment length by a Poisson distribution. We examine the applicability of our model by analyzing experimental results with apoptotic cells. Our model enables us to satisfactorily interpret the experimental trends. Interestingly, this theoretical fitting of the experimental data provides kinetic information for the cleavage reaction.

  6. Analytical, Experimental, and Modelling Studies of Lunar and Terrestrial Rocks

    NASA Technical Reports Server (NTRS)

    Haskin, Larry A.

    1997-01-01

    The goal of our research has been to understand the paths and the processes of planetary evolution that produced planetary surface materials as we find them. Most of our work has been on lunar materials and processes. We have done studies that obtain geological knowledge from detailed examination of regolith materials and we have reported implications for future sample-collecting and on-surface robotic sensing missions. Our approach has been to study a suite of materials that we have chosen in order to answer specific geologic questions. We continue this work under NAG5-4172. The foundation of our work has been the study of materials with precise chemical and petrographic analyses, emphasizing analysis for trace chemical elements. We have used quantitative models as tests to account for the chemical compositions and mineralogical properties of the materials in terms of regolith processes and igneous processes. We have done experiments as needed to provide values for geochemical parameters used in the models. Our models take explicitly into account the physical as well as the chemical processes that produced or modified the materials. Our approach to planetary geoscience owes much to our experience in terrestrial geoscience, where samples can be collected in field context and sampling sites revisited if necessary. Through studies of terrestrial analog materials, we have tested our ideas about the origins of lunar materials. We have been mainly concerned with the materials of the lunar highland regolith, their properties, their modes of origin, their provenance, and how to extrapolate from their characteristics to learn about the origin and evolution of the Moon's early igneous crust. From this work a modified model for the Moon's structure and evolution is emerging, one of globally asymmetric differentiation of the crust and mantle to produce a crust consisting mainly of ferroan and magnesian igneous rocks containing on average 70-80% plagioclase, with a large

  7. Peripheral opioid analgesia in experimental human pain models.

    PubMed

    Tegeder, Irmgard; Meier, Silke; Burian, Maria; Schmidt, Helmut; Geisslinger, Gerd; Lötsch, Jörn

    2003-05-01

    This placebo-controlled, double-blind crossover study assessed whether exclusive activation of peripheral opioid receptors results in significant pain reduction. To achieve opioid activity restricted to the periphery, we used a short-term (2 h) low dose infusion of morphine-6-beta-glucuronide (M6G) because M6G does not pass the blood-brain barrier during this time in amounts sufficient to induce CNS effects. The lack of central opioid effects of M6G was confirmed by a lack of change of the pupil size and absence of other opioid-related CNS effects. As a positive control, morphine was infused at a dosage that definitely produced CNS effects. This was evident by a rapid decrease of the pupil size and by other typical opioid-related side effects including nausea, vomiting, itchiness, hiccup and sedation. Three different pain models were employed to evaluate the analgesic effects: (i) cutaneous inflammatory hyperalgesia induced by briefly freezing a small skin area to -30 degrees C ('freeze lesion'); (ii) muscle hyperalgesia induced by a series of concentric and eccentric muscle contractions (DOMS model; delayed onset of muscle soreness); and (iii) pain induced by electrical current (5 Hz sinus stimuli of 0-10 mA). M6G significantly reduced cutaneous hyperalgesia in the 'freeze lesion' model as assessed with von Frey hairs. It also reduced muscle hyperalgesia in the DOMS model. Electrical pain, however, was not affected by M6G. Morphine was significantly more active in the 'freeze lesion' and DOMS model, and also significantly increased the electrical pain threshold and tolerance. Subcutaneous tissue concentrations of M6G and morphine as assessed with microdialysis were about half those of the respective plasma concentrations. The results of the study indicate that M6G has antihyperalgesic effects in inflammatory pain through activation of peripheral opioid receptors. Since this occurs at concentrations that do not cause central opioid effects, M6G might be useful as a

  8. Experimental flow studies in an elastic Y-model.

    PubMed

    Mijovic, Budimir; Liepsch, Dieter

    2003-01-01

    To determine the causes and history of atherosclerosis it is necessary to understand the hemodynamic parameters of blood circulation. Hemodynamic parameters play an important role in the formation of atherosclerotic plaques, especially near bends and bifurcations where the flow separates from the wall. Here the flow is laminar and non-axial with eddies, secondary flow, flow separation and stagnation points. Stenoses are found predominantly in flow separation areas. Therefore, it is important to separately study the following flow parameters: steady and pulsatile flow, wall elasticity and non-Newtonian flow behavior of blood. A simplified silicon elastic y-model simulating the human carotid artery was used for the analysis of these parameters. This model can be used for numerical studies as well. Flow was visualized at steady flow using dyes and at pulsatile flow with a photoelastic apparatus and a birefringent solution. The local axial velocity at steady and pulsatile flow was determined with a one-component Laser-Doppler-Anemometer (LDA). Pulsatile flow was generated by a piston membrane pump. A glycerin-water solution was used to simulate the Newtonian flow behavior of blood. A DMSO-Separan water solution was used to simulate the non-Newtonian flow behavior. Pulsatile flow creates higher and lower shear rates so called oscillating shear rate compare to steady flow depending on the velocity amplitude. The non-Newtonian fluid showed a markedly different flow behavior than the Newtonian fluid especially in areas of flow separation. Shear gradients were calculated from these velocity measurements using a bicubic spline interpolation. Shear stresses were calculated from these velocity shear gradients and the viscosity of the non-Newtonian fluid at these shear gradients. At special areas, high shear stresses > 10 Pa were found. The elasticity of the model wall also influences the flow behavior. The measurements showed that the characteristics of pulsatile flow and the

  9. Experimental determination of the radius of curvature of an isotropic Gaussian Schell-model beam.

    PubMed

    Zhu, Shijun; Chen, Yahong; Cai, Yangjian

    2013-02-01

    We propose a method to determine the radius of curvature of an isotropic Gaussian Schell-model (GSM) beam by measuring the transverse beam widths and the transverse coherence widths at two different planes. Furthermore, we carry out experimental determination of the radius of curvature of a GSM beam. Using the measured beam parameters, we carry out a comparative study of the propagation properties of a GSM beam both theoretically and experimentally. Our experimental results agree well with theoretical predictions.

  10. JANNUS: experimental validation at the scale of atomic modelling

    NASA Astrophysics Data System (ADS)

    Serruys, Yves; Ruault, Marie-Odile; Trocellier, Patrick; Miro, Sandrine; Barbu, Alain; Boulanger, Loïc; Kaïtasov, Odile; Henry, Sylvain; Leseigneur, Olivier; Trouslard, Philippe; Pellegrino, Stéphanie; Vaubaillon, Sylvain

    2008-04-01

    Ion irradiation is well suited to simulate neutron irradiation because primary knock-on atoms (PKA) produced by neutron collisions are self ions of the target. As the main difference, the energy spectrum of ion-produced PKAs is somewhat broader than in the case of fast neutrons. Studies of the combined effects of target damaging, ion implantation effects, helium and hydrogen production, and the occurrence of nuclear reactions should be performed by co-irradiation experiments (dual or triple beam irradiation). The JANNUS project (Joint Accelerators for Nanosciences and NUclear Simulation) was started in 2002 in the frame of a collaboration between CEA (Commissariat à l'Énergie Atomique) and CNRS-IN2P3 (Centre National de la Recherche Scientifique-Institut National de Physique Nucléaire et de Physique des Particules). Two experimental sites are involved. At Saclay, three electrostatic accelerators are being coupled: a new 3 MV Pelletron™ machine equipped with an ECR multi-charged ion source, a 2.5 MV single ended Van de Graaff and a 2.25 MV General Ionex tandem. At Orsay, the 2 MV tandem ARAMIS and the 190 kV ion implanter IRMA are being coupled with a 200 kV TECNAI™ transmission electron microscope to allow simultaneous co-irradiation and observation. This paper will first discuss both advantages and limitations of the use of ion beam irradiation to simulate neutron irradiation. A technical description of both set-ups is then presented, and some details will be given concerning multi-irradiation facilities running worldwide. The main application fields of JANNUS will be further detailed. To cite this article: Y. Serruys et al., C. R. Physique 9 (2008).

  11. Stochastic Approach for Modeling of DNAPL Migration in Heterogeneous Aquifers: Model Development and Experimental Data Generation

    NASA Astrophysics Data System (ADS)

    Dean, D. W.; Illangasekare, T. H.; Turner, A.; Russell, T. F.

    2004-12-01

    Modeling of the complex behavior of DNAPLs in naturally heterogeneous subsurface formations poses many challenges. Even though considerable progress have been made in developing improved numerical schemes to solve the governing partial differential equations, most of these methods still rely on deterministic description of the processes. This research explores the use of stochastic differential equations to model multiphase flow in heterogeneous aquifers, specifically the flow of DNAPLs in saturated soils. The models developed are evaluated using experimental data generated in two-dimensional test systems. A fundamental assumption used in the model formulation is that the movement of a fluid particle in each phase is described by a stochastic process and that the positions of all fluid particles over time are governed by a specific law. It is this law, which we seek to determine. The approach results in a nonlinear stochastic differential equation describing the position of the non-wetting phase fluid particle. The nonlinearity in the stochastic differential equation arises because both the drift and diffusion coefficients depend on the volumetric fraction of the phase, which in turn depends on the position of the fluid particles in the problem domain. The concept of a fluid particle is central to the development of the proposed model. Expressions for both saturation and volumetric fraction are developed using this concept of fluid particle. Darcy's law and the continuity equation are used to derive a Fokker-Planck equation governing flow. The Ito calculus is then applied to derive a stochastic differential equation(SDE) for the non-wetting phase. This SDE has both drift and diffusion terms which depend on the volumetric fraction of the non-wetting phase. Standard stochastic theories based on the Ito calculus and the Wiener process and the equivalent Fokker-Planck PDE's are typically used to model diffusion processes. However, these models, in their usual form

  12. Inference of ICF implosion core mix using experimental data and theoretical mix modeling

    SciTech Connect

    Sherrill, Leslie Welser; Haynes, Donald A; Cooley, James H; Sherrill, Manolo E; Mancini, Roberto C; Tommasini, Riccardo; Golovkin, Igor E; Haan, Steven W

    2009-01-01

    The mixing between fuel and shell materials in Inertial Confinement Fusion (lCF) implosion cores is a current topic of interest. The goal of this work was to design direct-drive ICF experiments which have varying levels of mix, and subsequently to extract information on mixing directly from the experimental data using spectroscopic techniques. The experimental design was accomplished using hydrodynamic simulations in conjunction with Haan's saturation model, which was used to predict the mix levels of candidate experimental configurations. These theoretical predictions were then compared to the mixing information which was extracted from the experimental data, and it was found that Haan's mix model predicted trends in the width of the mix layer as a function of initial shell thickness. These results contribute to an assessment of the range of validity and predictive capability of the Haan saturation model, as well as increasing confidence in the methods used to extract mixing information from experimental data.

  13. Uterine glands: development, function and experimental model systems.

    PubMed

    Cooke, Paul S; Spencer, Thomas E; Bartol, Frank F; Hayashi, Kanako

    2013-09-01

    Development of uterine glands (adenogenesis) in mammals typically begins during the early post-natal period and involves budding of nascent glands from the luminal epithelium and extensive cell proliferation in these structures as they grow into the surrounding stroma, elongate and mature. Uterine glands are essential for pregnancy, as demonstrated by the infertility that results from inhibiting the development of these glands through gene mutation or epigenetic strategies. Several genes, including forkhead box A2, beta-catenin and members of the Wnt and Hox gene families, are implicated in uterine gland development. Progestins inhibit uterine epithelial proliferation, and this has been employed as a strategy to develop a model in which progestin treatment of ewes for 8 weeks from birth produces infertile adults lacking uterine glands. More recently, mouse models have been developed in which neonatal progestin treatment was used to permanently inhibit adenogenesis and adult fertility. These studies revealed a narrow and well-defined window in which progestin treatments induced permanent infertility by impairing neonatal gland development and establishing endometrial changes that result in implantation defects. These model systems are being utilized to better understand the molecular mechanisms underlying uterine adenogenesis and endometrial function. The ability of neonatal progestin treatment in sheep and mice to produce infertility suggests that an approach of this kind may provide a contraceptive strategy with application in other species. Recent studies have defined the temporal patterns of adenogenesis in uteri of neonatal and juvenile dogs and work is underway to determine whether neonatal progestin or other steroid hormone treatments might be a viable contraceptive approach in this species.

  14. Experimentally validated pencil beam scanning source model in TOPAS.

    PubMed

    Lin, Liyong; Kang, Minglei; Solberg, Timothy D; Ainsley, Christopher G; McDonough, James E

    2014-11-21

    The presence of a low-dose envelope, or 'halo', in the fluence profile of a proton spot can increase the output of a pencil beam scanning field by over 10%. This study evaluated whether the Monte Carlo simulation code, TOPAS 1.0-beta 8, based on Geant4.9.6 with its default physics list, can predict the spot halo at depth in phantom by incorporating a halo model within the proton source distribution. Proton sources were modelled using three 2D Gaussian functions, and optimized until simulated spot profiles matched measurements at the phantom surface out to a radius of 100 mm. Simulations were subsequently compared with profiles measured using EBT3 film in Solidwater® phantoms at various depths for 100, 115, 150, 180, 210 and 225 MeV proton beams. Simulations predict measured profiles within a 1 mm distance to agreement for 2D profiles extending to the 0.1% isodose, and within 1 mm/1% Gamma criteria over the integrated curve of spot profile as a function of radius. For isodose lines beyond 0.1% of the central spot dose, the simulated primary spot sigma is smaller than the measurement by up to 15%, and can differ by over 1 mm. The choice of particle interaction algorithm and phantom material were found to cause ~1 mm range uncertainty, a maximal 5% (0.3 mm) difference in spot sigma, and maximal 1 mm and ~2 mm distance to agreement in isodoses above and below the 0.1% level, respectively. Based on these observations, therefore, the selection of physics model and the application of Solidwater® as water replacement material in simulation and measurement should be used with caution.

  15. Longitudinal variation of the equatorial ionosphere: Modeling and experimental results

    NASA Astrophysics Data System (ADS)

    Souza, J. R.; Asevedo, W. D.; dos Santos, P. C. P.; Petry, A.; Bailey, G. J.; Batista, I. S.; Abdu, M. A.

    2013-02-01

    We describe a new version of the Parameterized Regional Ionospheric Model (PARIM) which has been modified to include the longitudinal dependences. This model has been reconstructed using multidimensional Fourier series. To validate PARIM results, the South America maps of critical frequencies for the E (foE) and F (foF2) regions were compared with the values calculated by Sheffield Plasmasphere-Ionosphere Model (SUPIM) and IRI representations. PARIM presents very good results, the general characteristics of both regions, mainly the presence of the equatorial ionization anomaly, were well reproduced for equinoctial conditions of solar minimum and maximum. The values of foF2 and hmF2 recorded over Jicamarca (12°S; 77°W; dip lat. 1°N; mag. declination 0.3°) and sites of the conjugate point equatorial experiment (COPEX) campaign Boa Vista (2.8°N; 60.7°W; dip lat. 11.4°; mag. declination -13.1°), Cachimbo (9.5°S; 54.8°W; dip lat. -1.8°; mag. declination -15.5°), and Campo Grande (20.4°S; 54.6°W; dip lat. -11.1°; mag. declination -14.0°) have been used in this work. foF2 calculated by PARIM show good agreement with the observations, except during morning over Boa Vista and midnight-morning over Campo Grande. Some discrepancies were also found for the F-region peak height (hmF2) near the geomagnetic equator during times of F3 layer occurrences. IRI has underestimated both foF2 and hmF2 over equatorial and low latitude sectors during evening-nighttimes, except for Jicamarca where foF2 values were overestimated.

  16. Experimental models for contamination of titanium surfaces and disinfection protocols.

    PubMed

    Sousa, Vanessa; Mardas, Nikos; Spratt, David; Boniface, David; Dard, Michel; Donos, Nikolaos

    2016-10-01

    The aim of this pilot study was to describe an in vitro model of peri-implantitis microcosm for contamination of titanium surfaces and an in vivo model for evaluating different disinfection strategies of titanium surfaces. Biofilms were grown in vitro for 30 days on sandblasted large-grit acid-etched (SLA) Ti discs (n = 69) in a constant depth film fermentor (CDFF) associated with peri-implantitis conditions. Four Swedish loop rabbits were randomly allocated in three test groups (T1 , T2 , T3 ) and one control group (C). In group C, two sterile SLA Ti discs were implanted/fixed in each tibia. In the test groups (to evaluate the potential of different surface disinfection techniques), one sterile and three previously disinfected SLA Ti discs were placed following different disinfection protocols: group T1 : the discs were treated with a titanium brush - TiB; group T2 : the discs were treated with the combination of TiB and photodynamic therapy; and group T3 : the discs were treated with TiB and 1%NaOCl plus 0.2%CHX. Tensile strength test and qualitative histological analysis were performed on all 16 discs after 4 weeks of healing. Thirty days following CDFF emulating peri-implantitis microcosm, all SLA Ti discs had a mean total viable aerobes and facultative anaerobes count of 8.06 log10  CFU/biofilm and anaerobes 8.32 log10  CFU/biofilm. Before implantation/fixation on the tibia, differences of log10  CFU/biofilm counts between control and test groups after post hoc adjustment were highly significant (P < 0.001). In the in vivo analysis, group C exhibited the highest tensile strength (67.60 N [25.64-127.02]) and the histological sections revealed the presence of dense mature bone in direct contact with the disc surface. The analysis at the test groups showed that T2 presented with the highest tensile strength in comparison with the other two test groups. The in vitro model used in this study provides a valuable and reproducible tool for evaluating

  17. Experimental Research on Rail Vehicle Safety Using Dynamically Scaled Models.

    DTIC Science & Technology

    1976-01-01

    the first year of the program (June 29, 1976- June 28, 1977) includes: (1) the design and fabrication of a scale model track, single wheelset , test...carriage, and associated instrumentation; (2) measurement of wheelset displacement-force characteristics at steady velocity; (3) measurement of wheel...8217 •—" ’ * • -""* •• ’ ••’ ’ "• •— .•••»-.-»— •- •- - - - c) Design of wheelset carriage, linkage, and instrumentation systems. Various

  18. Cardiac resynchronization: Insight from experimental and computational models

    PubMed Central

    Kerckhoffs, R.C.P.; Lumens, J.; Vernooy, K.; Omens, J.H.; Mulligan, L.J.; Delhaas, T.; Arts, T.; McCulloch, A.D.; Prinzen, F.W.

    2009-01-01

    Cardiac resynchronization therapy (CRT) is a promising therapy for heart failure patients with a conduction disturbance, such as left bundle branch block. The aim of CRT is to resynchronize contraction between and within ventricles. However, about 30% of patients do not respond to this therapy. Therefore, a better understanding is needed for the relation between electrical and mechanical activation. In this paper, we focus on to what extent animal experiments and mathematical models can help in order to understand the pathophysiology of asynchrony to further improve CRT. PMID:18417196

  19. Comparison of Modeling and Experimental Approaches for Improved Modeling of Filtration in Granular and Consolidated Media

    NASA Astrophysics Data System (ADS)

    Mirabolghasemi, M.; Prodanovic, M.; DiCarlo, D. A.

    2014-12-01

    Filtration is relevant to many disciplines from colloid transport in environmental engineering to formation damage in petroleum engineering. In this study we compare the results of the novel numerical modeling of filtration phenomenon on pore scale with the complementary experimental observations on laboratory scale and discuss how the results of comparison can be used to improve macroscale filtration models for different porous media. The water suspension contained glass beads of 200 micron diameter and flows through a packing of 1mm diameter glass beads, and thus the main filtration mechanism is straining and jamming of particles. The numerical model simulates the flow of suspension through a realistic 3D structure of an imaged, disordered sphere pack, which acts as the filter medium. Particle capture through size exclusion and jamming is modeled via a coupled Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) approach. The coupled CFD-DEM approach is capable of modeling the majority of particle-particle, particle-wall, and particle-fluid interactions. Note that most of traditional approaches require spherical particles both in suspension and the filtration medium. We adapted the interface between the pore