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Sample records for 1-g model tests

  1. Correlation of AH-1G airframe test data with a NASTRAN mathematical model

    NASA Technical Reports Server (NTRS)

    Cronkhite, J. D.; Berry, V. L.

    1976-01-01

    Test data was provided for evaluating a mathematical vibration model of the Bell AH-1G helicopter airframe. The math model was developed and analyzed using the NASTRAN structural analysis computer program. Data from static and dynamic tests were used for comparison with the math model. Static tests of the fuselage and tailboom were conducted to verify the stiffness representation of the NASTRAN model. Dynamic test data were obtained from shake tests of the airframe and were used to evaluate the NASTRAN model for representing the low frequency (below 30 Hz) vibration response of the airframe.

  2. Summary of the modeling and test correlations of a NASTRAN finite element vibrations model for the AH-1G helicopter, task 1

    NASA Technical Reports Server (NTRS)

    Cronkhite, J. D.; Berry, V. L.; Dompka, R. V.

    1987-01-01

    The AH-1G NASTRAN finite element model (FEM) is described and the correlations with measured data that were conducted to verify the model are summarized. Comparisons of the AH-1G NASTRAN FEM calculations with measured data include the following: (1) fuselage and tailboom static load deflection (stiffness) testing, (2) airframe ground vibration testing (0-30 H<), (3) airframe flight vibration testing (main rotor, 2,4, and 6/rev), and (4) tailboom effective skin static testing. A description of the modeling rationale and techniques used to develop the NASTRAN FEM is presented in conjunction with all previous correlation work. In general, the correlations show good agreement between analysis and test in stiffness and vibration response through 15 to 20 Hz. For higher frequencies (equal to or greater than 4/rev (21.6 Hz)), the vibration responses generally did not agree well. Also, the lateral (2/rev (10.8 Hz)) flight vibration responses were much lower in the FEM than test, indicating that there is a significant excitation source other than at the main rotor hub that is affecting the lateral vibrations, such as downwash impingement on the vertical tail.

  3. Investigation of difficult component effects on finite element model vibration prediction for the Bell AH-1G helicopter. Volume 1: Ground vibration test results

    NASA Technical Reports Server (NTRS)

    Dompka, R. V.

    1989-01-01

    Under the NASA-sponsored Design Analysis Methods for VIBrationS (DAMVIBS) program, a series of ground vibration tests and NASTRAN finite element model (FEM) correlations were conducted on the Bell AH-1G helicopter gunship to investigate the effects of difficult components on the vibration response of the airframe. Previous correlations of the AH-1G showed good agreement between NASTRAN and tests through 15 to 20 Hz, but poor agreement in the higher frequency range of 20 to 30 Hz. Thus, this effort emphasized the higher frequency airframe vibration response correlations and identified areas that need further R and T work. To conduct the investigations, selected difficult components (main rotor pylon, secondary structure, nonstructural doors/panels, landing gear, engine, fuel, etc.) were systematically removed to quantify their effects on overall vibratory response of the airframe. The entire effort was planned and documented, and the results reviewed by NASA and industry experts in order to ensure scientific control of the testing, analysis, and correlation exercise. In particular, secondary structure and damping had significant effects on the frequency response of the airframe above 15 Hz. Also, the nonlinear effects of thrust stiffening and elastomer mounts were significant on the low frequency pylon modes below main rotor 1p (5.4 Hz). The results of the ground vibration testing are presented.

  4. Still Just 1 "g": Consistent Results from Five Test Batteries

    ERIC Educational Resources Information Center

    Johnson, Wendy; te Nijenhuis, Jan; Bouchard, Thomas J., Jr.

    2008-01-01

    In a recent paper, Johnson, Bouchard, Krueger, McGue, and Gottesman (2004) addressed a long-standing debate in psychology by demonstrating that the g factors derived from three test batteries administered to a single group of individuals were completely correlated. This finding provided evidence for the existence of a unitary higher-level general…

  5. Still Just 1 "g": Consistent Results from Five Test Batteries

    ERIC Educational Resources Information Center

    Johnson, Wendy; te Nijenhuis, Jan; Bouchard, Thomas J., Jr.

    2008-01-01

    In a recent paper, Johnson, Bouchard, Krueger, McGue, and Gottesman (2004) addressed a long-standing debate in psychology by demonstrating that the g factors derived from three test batteries administered to a single group of individuals were completely correlated. This finding provided evidence for the existence of a unitary higher-level general…

  6. Development, documentation and correlation of a NASTRAN vibration model of the AH-1G helicopter airframe

    NASA Technical Reports Server (NTRS)

    Cronkhite, J. D.

    1976-01-01

    NASTRAN was evaluated for vibration analysis of the helicopter airframe. The first effort involved development of a NASTRAN model of the AH-1G helicopter airframe and comprehensive documentation of the model. The next effort was to assess the validity of the NASTRAN model by comparisons with static and vibration tests.

  7. Some Important Aspects of Physical Modelling of Liquefaction in 1-g Shaking Table

    SciTech Connect

    Alam, Md. Jahangir; Towhata, Ikuo

    2008-07-08

    Physical modeling of liquefaction in 1-g shaking table and dynamic centrifuge test become very popular to simulate the ground behavior during earthquake motion. 1-g shaking table tests require scaled down model ground which can be prepared in three methods; water sedimentation, moist tamping and dry deposition method. Moist tamping and dry deposition method need saturation of model ground which is expensive and very difficult to achieve. Some model tests were performed in 1-g shaking table to see the influence of preparation method of model ground. Wet tamping and water sedimentation method of ground preparation were compared in these tests. Behavior of level ground and slope were also examined. Slope and level ground model test increased the understanding of excess pore pressure generation in both cases. Wet tamping method has a possibility of not being fully saturated. Pore pressure transducers should be fixed vertically so that it can not settle down during shaking but can move with ground. There was insignificant difference in acceleration and excess pore pressure responses between wet tamping and water sedimentation method in case of level ground. Spiky accelerations were prominent in slope prepared by water sedimentation method. Spiky accelerations were the result of lateral displacement induced dilatancy of soil.

  8. Cacna1g is a genetic modifier of epilepsy in a mouse model of Dravet syndrome.

    PubMed

    Calhoun, Jeffrey D; Hawkins, Nicole A; Zachwieja, Nicole J; Kearney, Jennifer A

    2017-08-01

    Dravet syndrome, an early onset epileptic encephalopathy, is most often caused by de novo mutation of the neuronal voltage-gated sodium channel gene SCN1A. Mouse models with deletion of Scn1a recapitulate Dravet syndrome phenotypes, including spontaneous generalized tonic-clonic seizures, susceptibility to seizures induced by elevated body temperature, and elevated risk of sudden unexpected death in epilepsy. Importantly, the epilepsy phenotype of Dravet mouse models is highly strain-dependent, suggesting a strong influence of genetic modifiers. We previously identified Cacna1g, encoding the Cav3.1 subunit of the T-type calcium channel family, as an epilepsy modifier in the Scn2a(Q54) transgenic epilepsy mouse model. In this study, we asked whether transgenic alteration of Cacna1g expression modifies severity of the Scn1a(+/-) Dravet phenotype. Scn1a(+/-) mice with decreased Cacna1g expression showed partial amelioration of disease phenotypes with improved survival and reduced spontaneous seizure frequency. However, reduced Cacna1g expression did not alter susceptibility to hyperthermia-induced seizures. Transgenic elevation of Cacna1g expression had no effect on the Scn1a(+/-) epilepsy phenotype. These results provide support for Cacna1g as a genetic modifier in a mouse model of Dravet syndrome and suggest that Cav3.1 may be a potential molecular target for therapeutic intervention in patients. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

  9. Measuring Neuromuscular Junction Functionality in the SOD1(G93A) Animal Model of Amyotrophic Lateral Sclerosis.

    PubMed

    Rizzuto, Emanuele; Pisu, Simona; Musarò, Antonio; Del Prete, Zaccaria

    2015-09-01

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that leads to motor neuron degeneration, alteration in neuromuscular junctions (NMJs), muscle atrophy, and paralysis. To investigate the NMJ functionality in ALS we tested, in vitro, two innervated muscle types excised from SOD1(G93A) transgenic mice at the end-stage of the disease: the Soleus, a postural muscle almost completely paralyzed at that stage, and the diaphragm, which, on the contrary, is functional until death. To this aim we employed an experimental protocol that combined two types of electrical stimulation: the direct stimulation and the stimulation through the nerve. The technique we applied allowed us to determine the relevance of NMJ functionality separately from muscle contractile properties in SOD1(G93A) animal model. Functional measurements revealed that the muscle contractility of transgenic diaphragms is almost unaltered in comparison to control muscles, while transgenic Soleus muscles were severely compromised. In contrast, when stimulated via the nerve, both transgenic muscle types showed a strong decrease of the contraction force, a slowing down of the kinetic parameters, as well as alterations in the neurotransmission failure parameter. All together, these results confirm a severely impaired functionality in the SOD1(G93A) neuromuscular junctions.

  10. Healing activity of proteolytic fraction (P1G10) from Vasconcellea cundinamarcensis in a cutaneous wound excision model.

    PubMed

    Freitas, K M; Barcelos, L S; Caliari, M V; Salas, C E; Lopes, M T P

    2017-10-05

    The proteolytic enzymes from Vasconcellea cundinamarcensis have demonstrated efficacy to accelerate healing of skin lesions. We report here the efficacy of the proteolytic fraction - P1G10 during repair of excisional wounds in rodent model and analyze possible mediators involved. Using 0.05% P1G10 we observed on day 3rd increased wound contraction accompanied by an increase in activated neutrophils and VEGF relative to the control. On day 7th neutrophils returned to normal levels, and at 0.01% P1G10, an increase in NAG activity used to monitor monocyte/macrophage, was observed. On the other hand, on day 7th, we observed a decrease in TGF-β at 0.05% P1G10, accompanied by an increased transformation of the latent TGF-β to its active form. Also, on day 7th a reduction in MMP-9 activity and the number of apoptotic cells was observed along with an increase in fibroblast levels. Morphometrically, it appears that treatment with P1G10 accelerates the decline of initial inflammatory phase and reduces some unwanted effects likely caused by remaining TGF-β or MMPs, thus enhancing the quality of scar. Overall, these data suggest that the active proteolytic fraction P1G10 enhances the efficacy of repair in excisional cutaneous wounds. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  11. Effects of Tongue Force Training on Bulbar Motor Function in the Female SOD1-G93A Rat Model of Amyotrophic Lateral Sclerosis.

    PubMed

    Ma, Delin; Shuler, Jeffrey M; Kumar, Aishwarya; Stanford, Quincy R; Tungtur, Sudheer; Nishimune, Hiroshi; Stanford, John A

    2017-02-01

    The use of exercise in amyotrophic lateral sclerosis (ALS) is controversial. Although moderate exercise appears to be beneficial for limb muscles in ALS, the effects of exercise on bulbar muscles such as the tongue have not been studied. To determine the effects of tongue force training on bulbar motor function in the SOD1-G93A rat model of ALS. We compared the effects of tongue force training on bulbar motor function and neuromuscular junction innervation in female SOD1-G93A rats and age-matched female wild-type controls. Half of each group underwent afternoon tongue force training sessions, and all rats were tested under minimal force conditions in the mornings. Tongue force did not differ between the SOD1-G93A rats and healthy controls during the morning testing sessions, nor was it affected by training. Surprisingly, decreases in tongue motility, the number of licks per session, and body weight were greater in the tongue force-trained SOD1-G93A rats. Forelimb grip force, survival, and denervation of the genioglossus (GG) muscle did not differ between the trained and untrained SOD1-G93A rats. GG innervation was correlated with changes in tongue force but not tongue motility in SOD1-G93A rats at end stage. The results indicate a potential deleterious effect of tongue force training on tongue motility in female SOD1-G93A rats. The lack of a relationship between GG innervation and tongue motility suggests that factors other than lower-motor neuron integrity likely accounted for this effect.

  12. Early detection of motor dysfunction in the SOD1G93A mouse model of Amyotrophic Lateral Sclerosis (ALS) using home cage running wheels.

    PubMed

    Bennett, Ellen J; Mead, Richard J; Azzouz, Mimoun; Shaw, Pamela J; Grierson, Andrew J

    2014-01-01

    The SOD1G93A mouse has been used since 1994 for preclinical testing in amyotrophic lateral sclerosis (ALS). Despite recent genetic advances in our understanding of ALS, transgenic mice expressing mutant SOD1 remain the best available, and most widely used, vertebrate model of the disease. We previously described an optimised and rapid approach for preclinical studies in the SOD1G93A mouse. Here we describe improvements to this approach using home cage running wheels to obtain daily measurements of motor function, with minimal intervention. We show that home cage running wheels detect reductions in motor function at a similar time to the rotarod test, and that the data obtained are less variable allowing the use of smaller groups of animals to obtain satisfactory results. This approach refines use of the SOD1G93A model, and reduces the number of animals undergoing procedures of substantial severity, two central principles of the 3Rs (replacement, reduction and refinement of animal use in research). The small group sizes and rapid timescales enable affordable large-scale therapeutic pre-screening in the SOD1G93A mouse, as well as rapid validation of published positive effects in a second laboratory, one of the major stumbling blocks in ALS preclinical therapy development.

  13. Molecular Chaperone Mediated Late-Stage Neuroprotection in the SOD1G93A Mouse Model of Amyotrophic Lateral Sclerosis

    PubMed Central

    Gray, Anna L.; Dick, James R.; Kanuga, Naheed; Kalmar, Bernadett; Greensmith, Linda; Cheetham, Michael E.

    2013-01-01

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the selective loss of motor neurons in the spinal cord, brain stem, and motor cortex. Mutations in superoxide dismutase (SOD1) are associated with familial ALS and lead to SOD1 protein misfolding and aggregation. Here we show that the molecular chaperone, HSJ1 (DNAJB2), mutations in which cause distal hereditary motor neuropathy, can reduce mutant SOD1 aggregation and improve motor neuron survival in mutant SOD1 models of ALS. Overexpression of human HSJ1a (hHSJ1a) in vivo in motor neurons of SOD1G93A transgenic mice ameliorated disease. In particular, there was a significant improvement in muscle force, increased motor unit number and enhanced motor neuron survival. hHSJ1a was present in a complex with SOD1G93A and led to reduced SOD1 aggregation at late stages of disease progression. We also observed altered ubiquitin immunoreactivity in the double transgenic animals, suggesting that ubiquitin modification might be important for the observed improvements. In a cell model of SOD1G93A aggregation, HSJ1a preferentially bound to mutant SOD1, enhanced SOD1 ubiquitylation and reduced SOD1 aggregation in a J-domain and ubiquitin interaction motif (UIM) dependent manner. Collectively, the data suggest that HSJ1a acts on mutant SOD1 through a combination of chaperone, co-chaperone and pro-ubiquitylation activity. These results show that targeting SOD1 protein misfolding and aggregation in vivo can be neuroprotective and suggest that manipulation of DnaJ molecular chaperones might be useful in the treatment of ALS. PMID:24023695

  14. Molecular chaperone mediated late-stage neuroprotection in the SOD1(G93A) mouse model of amyotrophic lateral sclerosis.

    PubMed

    Novoselov, Sergey S; Mustill, Wendy J; Gray, Anna L; Dick, James R; Kanuga, Naheed; Kalmar, Bernadett; Greensmith, Linda; Cheetham, Michael E

    2013-01-01

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the selective loss of motor neurons in the spinal cord, brain stem, and motor cortex. Mutations in superoxide dismutase (SOD1) are associated with familial ALS and lead to SOD1 protein misfolding and aggregation. Here we show that the molecular chaperone, HSJ1 (DNAJB2), mutations in which cause distal hereditary motor neuropathy, can reduce mutant SOD1 aggregation and improve motor neuron survival in mutant SOD1 models of ALS. Overexpression of human HSJ1a (hHSJ1a) in vivo in motor neurons of SOD1(G93A) transgenic mice ameliorated disease. In particular, there was a significant improvement in muscle force, increased motor unit number and enhanced motor neuron survival. hHSJ1a was present in a complex with SOD1(G93A) and led to reduced SOD1 aggregation at late stages of disease progression. We also observed altered ubiquitin immunoreactivity in the double transgenic animals, suggesting that ubiquitin modification might be important for the observed improvements. In a cell model of SOD1(G93A) aggregation, HSJ1a preferentially bound to mutant SOD1, enhanced SOD1 ubiquitylation and reduced SOD1 aggregation in a J-domain and ubiquitin interaction motif (UIM) dependent manner. Collectively, the data suggest that HSJ1a acts on mutant SOD1 through a combination of chaperone, co-chaperone and pro-ubiquitylation activity. These results show that targeting SOD1 protein misfolding and aggregation in vivo can be neuroprotective and suggest that manipulation of DnaJ molecular chaperones might be useful in the treatment of ALS.

  15. n-butylidenephthalide treatment prolongs life span and attenuates motor neuron loss in SOD1(G93A) mouse model of amyotrophic lateral sclerosis.

    PubMed

    Zhou, Qin-Ming; Zhang, Jing-Jing; Li, Song; Chen, Sheng; Le, Wei-Dong

    2017-05-01

    To evaluate the therapeutic effects of n-butylidenephthalide (BP) in SOD1(G93A) mouse model of amyotrophic lateral sclerosis and explore the possible mechanisms. The SOD1(G93A) mice were treated by oral administration of BP (q.d., 400 mg/kg d) starting from 60 days of age and continuing until death. The rotarod test was performed to assess the disease onset. The expression levels of apoptosis-related proteins, inflammatory molecules, and autophagy-associated proteins were determined. The number of apoptotic motor neurons and the extent of microglial and astroglial activation were also assessed in the lumbar spinal cords of BP-treated mice. Grip strength test, hematoxylin-eosin staining, nicotinamide adenine dinucleotide hydrogen staining, and malondialdehyde assay were conducted to evaluate the muscle function and pathology. Although BP treatment did not delay the disease onset, it prolonged the life span and thereafter extended the disease duration in SOD1(G93A) mouse model of ALS. BP treatment also reduced the motor neuron loss through inhibiting apoptosis. We further demonstrated that the neuroprotective effects of BP might be resulted from the inhibition of inflammatory, oxidative stress, and autophagy. Our study suggests that BP may be a promising candidate for the treatment of ALS. © 2017 John Wiley & Sons Ltd.

  16. Tempol moderately extends survival in a hSOD1(G93A) ALS rat model by inhibiting neuronal cell loss, oxidative damage and levels of non-native hSOD1(G93A) forms.

    PubMed

    Linares, Edlaine; Seixas, Luciana V; dos Prazeres, Janaina N; Ladd, Fernando V L; Ladd, Aliny A B L; Coppi, Antonio A; Augusto, Ohara

    2013-01-01

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive dysfunction and death of motor neurons by mechanisms that remain unclear. Evidence indicates that oxidative mechanisms contribute to ALS pathology, but classical antioxidants have not performed well in clinical trials. Cyclic nitroxides are an alternative worth exploring because they are multifunctional antioxidants that display low toxicity in vivo. Here, we examine the effects of the cyclic nitroxide tempol (4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl) on ALS onset and progression in transgenic female rats over-expressing the mutant hSOD1(G93A) . Starting at 7 weeks of age, a high dose of tempol (155 mg/day/rat) in the rat´s drinking water had marginal effects on the disease onset but decelerated disease progression and extended survival by 9 days. In addition, tempol protected spinal cord tissues as monitored by the number of neuronal cells, and the reducing capability and levels of carbonylated proteins and non-native hSOD1 forms in spinal cord homogenates. Intraperitoneal tempol (26 mg/rat, 3 times/week) extended survival by 17 days. This group of rats, however, diverted to a decelerated disease progression. Therefore, it was inconclusive whether the higher protective effect of the lower i.p. dose was due to higher tempol bioavailability, decelerated disease development or both. Collectively, the results show that tempol moderately extends the survival of ALS rats while protecting their cellular and molecular structures against damage. Thus, the results provide proof that cyclic nitroxides are alternatives worth to be further tested in animal models of ALS.

  17. Functional over-load saves motor units in the SOD1-G93A transgenic mouse model of amyotrophic lateral sclerosis.

    PubMed

    Gordon, T; Tyreman, N; Li, S; Putman, C T; Hegedus, J

    2010-02-01

    The fastest, most forceful motor units are lost progressively during asymptomatic disease in the SOD1(G93A) transgenic mouse model of amyotrophic lateral sclerosis. As the disease progresses the surviving motor units must increase their levels of activity to sustain posture and movement. If activity-dependent conversion of motor units to more fatigue resistant types increased their resilience and hence survival, we hypothesized that an experimental increase in motor unit activity in the hindlimb muscles of the SOD1(G93A) transgenic mouse should "save" those motor units that are normally lost in the first 90 days of age. To test this hypothesis, we partially denervated hindlimb muscles in SOD1(G93A) and their corresponding control SOD1(WT) transgenic mice by avulsion of either L4 or L5 spinal roots at 40 days of age. Whole muscle and single motor unit isometric twitch forces were recorded and the numbers intact motor units in fast-twitch tibialis anterior, medial gastrocnemius, extensor digitorum longus muscles and the slow-twitch soleus muscle were calculated at 90 days of age. We found that the rapid age-dependent decline in numbers of functional motor units in fast-twitch muscles of the SOD1(G93A) transgenic mice was dramatically reduced by the functional hyperactivity in the partially denervated muscles and, that these muscles comprised a significantly higher component of type IIA and type IID/X fibers than those muscles that were innervated by nerves in intact spinal roots. We conclude that the vulnerable motor units are saved by increasing their neuromuscular activity and consequently, converting them to slower, less forceful, fatigue resistant motor units.

  18. Characterization of early pathogenesis in the SOD1G93A mouse model of ALS: part I, background and methods

    PubMed Central

    Vinsant, Sharon; Mansfield, Carol; Jimenez-Moreno, Ramon; Del Gaizo Moore, Victoria; Yoshikawa, Masaaki; Hampton, Thomas G; Prevette, David; Caress, James; Oppenheim, Ronald W; Milligan, Carol

    2013-01-01

    Charcot first described amyotrophic lateral sclerosis (ALS) in 1869; however, its causes remain largely unknown and effective, long-term treatment strategies are not available. The first mouse model of ALS was developed after the identification of mutations in the superoxide dismutase 1 (SOD1) gene in 1993, and accordingly most of our knowledge of the etiology and pathogenesis of the disease comes from studies carried out using this animal model. Although numerous preclinical trials have been conducted in the mutant SOD1 mouse models, the results have been disappointing because they did not positively translate to clinical trials. One explanation may be that current understanding of when and where pathogenesis begins is insufficient to accurately guide preclinical trials. Further characterization of these early events may provide insight into disease onset, help in the discovery of presymptomatic diagnostic disease markers, and identify novel therapeutic targets. Here, we describe the rationale, approach, and methods for our extensive analysis of early changes that included an ultrastructural examination of central and peripheral components of the neuromuscular system in the SOD1G93A mouse and correlated these alterations with early muscle denervation, motor dysfunction, and motoneuron death. We also provide a discussion of published work to review what is known regarding early pathology in the SOD1 mouse model of ALS. The significance of this work is that we have examined early pathology simultaneously in both the spinal cord and peripheral neuromuscular system, and the results are presented in the companion paper (Part II, Results and Discussion). Our results provide evidence as to why a thorough characterization of animal models throughout the life span is critical for a strong foundation to design preclinical trials that may produce meaningful results. PMID:24381807

  19. Correlation of AH-1G helicopter flight vibration data and tailboom static test data with NASTRAN analytical results

    NASA Technical Reports Server (NTRS)

    Cronkhite, J. D.; Wilson, H. E.; Berry, V. L.

    1976-01-01

    Level flight airframe vibration at main rotor excitation frequencies was calculated. A NASTRAN tailboom analysis was compared with test data for evaluation of methods used to determine effective skin in a semimonocoque sheet-stringer structure. The flight vibration correlation involved comparison of level flight vibration for two helicopter configurations: clean wing, at light gross weight and wing stores at heavy gross weight. In the tailboom correlation, deflections and internal loads were compared using static test data and a NASTRAN analysis. An iterative procedure was used to determine the amount of effective skin of buckled panels under compression load.

  20. Investigation of difficult component effects on finite element model vibration prediction for the Bell AG-1G helicopter. Volume 2: Correlation results

    NASA Technical Reports Server (NTRS)

    Dompka, R. V.

    1989-01-01

    Under the NASA-sponsored DAMVIBS (Design Analysis Methods for VIBrationS) program, a series of ground vibration tests and NASTRAN finite element model (FEM) correlations were conducted on the Bell AH-1G helicopter gunship to investigate the effects of difficult components on the vibration response of the airframe. Previous correlations of the AG-1G showed good agreement between NASTRAN and tests through 15 to 20 Hz, but poor agreement in the higher frequency range of 20 to 30 Hz. Thus, this effort emphasized the higher frequency airframe vibration response correlations and identified areas that need further R and T work. To conduct the investigations, selected difficult components (main rotor pylon, secondary structure, nonstructural doors/panels, landing gear, engine, furl, etc.) were systematically removed to quantify their effects on overall vibratory response of the airframe. The entire effort was planned and documented, and the results reviewed by NASA and industry experts in order to ensure scientific control of the testing, analysis, and correlation exercise. In particular, secondary structure and damping had significant effects on the frequency response of the airframe above 15 Hz. Also, the nonlinear effects of thrust stiffening and elastomer mounts were significant on the low frequency pylon modes below main rotor 1p (5.4 Hz). The results of the NASTRAN FEM correlations are given.

  1. Alterations in the motor neuron-Renshaw cell circuit in the Sod1G93A mouse model

    PubMed Central

    Wootz, Hanna; FitzSimons-Kantamneni, Eileen; Larhammar, Martin; Rotterman, Travis M.; Enjin, Anders; Patra, Kalicharan; Andre, Elodie; van Zundert, Brigitte; Kullander, Klas; Alvarez, Francisco J.

    2012-01-01

    Motor neurons become hyperexcitable during progression of amyotrophic lateral sclerosis (ALS). This abnormal firing behavior has been explained by changes in their membrane properties, but more recently it has been suggested that changes in premotor circuits may also contribute to this abnormal activity. The specific circuits that may be altered during development of ALS have not been investigated. Here we examined the Renshaw cell recurrent circuit that exerts inhibitory feedback control on motor neuron firing. Using two markers for Renshaw cells (calbindin and Chrna2 , cholinergic nicotinic receptor subunit alpha2), two general markers for motor neurons (NeuN and VAChT, vesicular acethylcholine transporter ) and two markers for fast motor neurons (Chondrolectin and Calca, calcitonin-related polypeptide alpha), we analyzed the survival and connectivity of these cells during disease progression in the Sod1G93A mouse model. Most calbindin-immunoreactive (IR) Renshaw cells survive to end-stage but downregulate postsynaptic Chrna2 in presymptomatic animals. In motor neurons, some markers are downregulated early (NeuN, VAChT, Chondrolectin) and others at end-stage(Calca). Early downregulation of presynaptic VAChT and Chrna2 was correlated with disconnection from Renshaw cells as well as major structural abnormalities of motor axon synapses inside the spinal cord. Renshaw cell synapses on motor neurons underwent more complex changes, including transitional sprouting preferentially over remaining NeuN-IR motor neurons. We conclude that the loss of presynaptic motor axon input on Renshaw cells occurs at early stages of ALS and disconnects the recurrent inhibitory circuit, presumably resulting in a diminished control of motor neuron firing. PMID:23172249

  2. Optimised and Rapid Pre-clinical Screening in the SOD1G93A Transgenic Mouse Model of Amyotrophic Lateral Sclerosis (ALS)

    PubMed Central

    Mead, Richard J.; Bennett, Ellen J.; Kennerley, Aneurin J.; Sharp, Paul; Sunyach, Claire; Kasher, Paul; Berwick, Jason; Pettmann, Brigitte; Battaglia, Guiseppe; Azzouz, Mimoun; Grierson, Andrew; Shaw, Pamela J.

    2011-01-01

    The human SOD1G93A transgenic mouse has been used extensively since its development in 1994 as a model for amyotrophic lateral sclerosis (ALS). In that time, a great many insights into the toxicity of mutant SOD1 have been gained using this and other mutant SOD transgenic mouse models. They all demonstrate a selective toxicity towards motor neurons and in some cases features of the pathology seen in the human disease. These models have two major drawbacks. Firstly the generation of robust preclinical data in these models has been highlighted as an area for concern. Secondly, the amount of time required for a single preclinical experiment in these models (3–4 months) is a hurdle to the development of new therapies. We have developed an inbred C57BL/6 mouse line from the original mixed background (SJLxC57BL/6) SOD1G93A transgenic line and show here that the disease course is remarkably consistent and much less prone to background noise, enabling reduced numbers of mice for testing of therapeutics. Secondly we have identified very early readouts showing a large decline in motor function compared to normal mice. This loss of motor function has allowed us to develop an early, sensitive and rapid screening protocol for the initial phases of denervation of muscle fibers, observed in this model. We describe multiple, quantitative readouts of motor function that can be used to interrogate this early mechanism. Such an approach will increase throughput for reduced costs, whilst reducing the severity of the experimental procedures involved. PMID:21876739

  3. Optimised and rapid pre-clinical screening in the SOD1(G93A) transgenic mouse model of amyotrophic lateral sclerosis (ALS).

    PubMed

    Mead, Richard J; Bennett, Ellen J; Kennerley, Aneurin J; Sharp, Paul; Sunyach, Claire; Kasher, Paul; Berwick, Jason; Pettmann, Brigitte; Battaglia, Guiseppe; Azzouz, Mimoun; Grierson, Andrew; Shaw, Pamela J

    2011-01-01

    The human SOD1(G93A) transgenic mouse has been used extensively since its development in 1994 as a model for amyotrophic lateral sclerosis (ALS). In that time, a great many insights into the toxicity of mutant SOD1 have been gained using this and other mutant SOD transgenic mouse models. They all demonstrate a selective toxicity towards motor neurons and in some cases features of the pathology seen in the human disease. These models have two major drawbacks. Firstly the generation of robust preclinical data in these models has been highlighted as an area for concern. Secondly, the amount of time required for a single preclinical experiment in these models (3-4 months) is a hurdle to the development of new therapies. We have developed an inbred C57BL/6 mouse line from the original mixed background (SJLxC57BL/6) SOD1(G93A) transgenic line and show here that the disease course is remarkably consistent and much less prone to background noise, enabling reduced numbers of mice for testing of therapeutics. Secondly we have identified very early readouts showing a large decline in motor function compared to normal mice. This loss of motor function has allowed us to develop an early, sensitive and rapid screening protocol for the initial phases of denervation of muscle fibers, observed in this model. We describe multiple, quantitative readouts of motor function that can be used to interrogate this early mechanism. Such an approach will increase throughput for reduced costs, whilst reducing the severity of the experimental procedures involved.

  4. PACAP signaling exerts opposing effects on neuroprotection and neuroinflammation during disease progression in the SOD1(G93A) mouse model of amyotrophic lateral sclerosis☆

    PubMed Central

    Ringer, Cornelia; Büning, Luisa-Sybille; Schäfer, Martin K.H.; Eiden, Lee E.; Weihe, Eberhard; Schütz, Burkhard

    2014-01-01

    Pituitary adenylate cyclase-activating polypeptide (PACAP) is a pleiotropic peptide with autocrine neuroprotective and paracrine anti-inflammatory properties in various models of acute neuronal damage and neurodegenerative diseases. Therefore, we examined a possible beneficial role of endogenous PACAP in the superoxide dismutase 1, SOD1(G93A), mouse model of amyotrophic lateral sclerosis (ALS), a lethal neurodegenerative disease particularly affecting somatomotor neurons. In wild-type mice, somatomotor and visceromotor neurons in brain stem and spinal cord were found to express the PACAP specific receptor PAC1, but only visceromotor neurons expressed PACAP as a potential autocrine source of regulation of these receptors. In SOD1(G93A) mice, only a small subset of the surviving somatomotor neurons showed induction of PACAP mRNA, and somatomotor neuron degeneration was unchanged in PACAP-deficient SOD1(G93A) mice. Pre-ganglionic sympathetic visceromotor neurons were found to be resistant in SOD1(G93A) mice, while pre-ganglionic parasympathetic neurons degenerated during ALS disease progression in this mouse model. PACAP-deficient SOD1(G93A) mice showed even greater pre-ganglionic parasympathetic neuron loss compared to SOD1(G93A) mice, and additional degeneration of pre-ganglionic sympathetic neurons. Thus, constitutive expression of PACAP and PAC1 may confer neuroprotection to central visceromotor neurons in SOD1(G93A) mice via autocrine pathways. Regarding the progression of neuroinflammation, the switch from amoeboid to hypertrophic microglial phenotype observed in SOD1(G93A) mice was absent in PACAP-deficient SOD1(G93A) mice. Thus, endogenous PACAP may promote microglial cytodestructive functions thought to drive ALS disease progression. This hypothesis was consistent with prolongation of life expectancy and preserved tongue motor function in PACAP-deficient SOD1(G93A) mice, compared to SOD1(G93A) mice. Given the protective role of PACAP expression in

  5. Soma size and Cav1.3 channel expression in vulnerable and resistant motoneuron populations of the SOD1G93A mouse model of ALS

    PubMed Central

    Shoenfeld, Liza; Westenbroek, Ruth E.; Fisher, Erika; Quinlan, Katharina A.; Tysseling, Vicki M.; Powers, Randall K.; Heckman, Charles J.; Binder, Marc D.

    2014-01-01

    Abstract Although the loss of motoneurons is an undisputed feature of amyotrophic lateral sclerosis (ALS) in man and in its animal models (SOD1 mutant mice), how the disease affects the size and excitability of motoneurons prior to their degeneration is not well understood. This study was designed to test the hypothesis that motoneurons in mutant SOD1G93A mice exhibit an enlargement of soma size (i.e., cross‐sectional area) and an increase in Cav1.3 channel expression at postnatal day 30, well before the manifestation of physiological symptoms that typically occur at p90 (Chiu et al. 1995). We made measurements of spinal and hypoglossal motoneurons vulnerable to degeneration, as well as motoneurons in the oculomotor nucleus that are resistant to degeneration. Overall, we found that the somata of motoneurons in male SOD1G93A mutants were larger than those in wild‐type transgenic males. When females were included in the two groups, significance was lost. Expression levels of the Cav1.3 channels were not differentiated by genotype, sex, or any interaction of the two. These results raise the intriguing possibility of an interaction between male sex steroid hormones and the SOD1 mutation in the etiopathogenesis of ALS. PMID:25107988

  6. Glycoprotein nonmetastatic melanoma protein B ameliorates skeletal muscle lesions in a SOD1G93A mouse model of amyotrophic lateral sclerosis.

    PubMed

    Nagahara, Yuki; Shimazawa, Masamitsu; Tanaka, Hirotaka; Ono, Yoko; Noda, Yasuhiro; Ohuchi, Kazuki; Tsuruma, Kazuhiro; Katsuno, Masahisa; Sobue, Gen; Hara, Hideaki

    2015-10-01

    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive loss of motor neurons and subsequent muscular atrophy. The quality of life of patients with ALS is significantly improved by ameliorating muscular symptoms. We previously reported that glycoprotein nonmetastatic melanoma protein B (GPNMB; osteoactivin) might serve as a target for ALS therapy. In the present study, superoxide dismutase 1/glycine residue 93 changed to alanine (SOD1(G93A) ) transgenic mice were used as a model of ALS. Expression of the C-terminal fragment of GPNMB was increased in the skeletal muscles of SOD1(G93A) mice and patients with sporadic ALS. SOD1(G93A) /GPNMB transgenic mice were generated to determine whether GPNMB expression ameliorates muscular symptoms. The weight and cross-sectional area of the gastrocnemius muscle, number and cross-sectional area of myofibers, and denervation of neuromuscular junctions were ameliorated in SOD1(G93A) /GPNMB vs. SOD1(G93A) mice. Furthermore, direct injection of a GPNMB expression plasmid into the gastrocnemius muscle of SOD1(G93A) mice increased the numbers of myofibers and prevented myofiber atrophy. These findings suggest that GPNMB directly affects skeletal muscle and prevents muscular pathology in SOD1(G93A) mice and may therefore serve as a target for therapy of ALS.

  7. Knocking down metabotropic glutamate receptor 1 improves survival and disease progression in the SOD1(G93A) mouse model of amyotrophic lateral sclerosis.

    PubMed

    Milanese, Marco; Giribaldi, Francesco; Melone, Marcello; Bonifacino, Tiziana; Musante, Ilaria; Carminati, Enrico; Rossi, Pia I A; Vergani, Laura; Voci, Adriana; Conti, Fiorenzo; Puliti, Aldamaria; Bonanno, Giambattista

    2014-04-01

    Amyotrophic lateral sclerosis (ALS) is a late-onset fatal neurodegenerative disease reflecting degeneration of upper and lower motoneurons (MNs). The cause of ALS and the mechanisms of neuronal death are still largely obscure, thus impairing the establishment of efficacious therapies. Glutamate (Glu)-mediated excitotoxicity plays a major role in MN degeneration in ALS. We recently demonstrated that the activation of Group I metabotropic Glu autoreceptors, belonging to both type 1 and type 5 receptors (mGluR1 and mGluR5), at glutamatergic spinal cord nerve terminals, produces excessive Glu release in mice over-expressing human superoxide-dismutase carrying the G93A point mutation (SOD1(G93A)), a widely used animal model of human ALS. To establish whether these receptors are implicated in ALS, we generated mice expressing half dosage of mGluR1 in the SOD1(G93A) background (SOD1(G93A)Grm1(crv4/+)), by crossing the SOD1(G93A) mutant mouse with the Grm1(crv4/+) mouse, lacking mGluR1 because of a spontaneous recessive mutation. SOD1(G93A)Grm1(crv4/+) mice showed prolonged survival probability, delayed pathology onset, slower disease progression and improved motor performances compared to SOD1(G93A) mice. These effects were associated to reduction of mGluR5 expression, enhanced number of MNs, decreased astrocyte and microglia activation, normalization of metallothionein and catalase mRNA expression, reduced mitochondrial damage, and decrease of abnormal Glu release in spinal cord of SOD1(G93A)Grm1(crv4/+)compared to SOD1(G93A) mice. These results demonstrate that a lower constitutive level of mGluR1 has a significant positive impact on mice with experimental ALS, thus providing the rationale for future pharmacological approaches to ALS by selectively blocking Group I metabotropic Glu receptors.

  8. Deletion of galectin-3 exacerbates microglial activation and accelerates disease progression and demise in a SOD1G93A mouse model of amyotrophic lateral sclerosis

    PubMed Central

    Lerman, Bruce J; Hoffman, Eric P; Sutherland, Margaret L; Bouri, Khaled; Hsu, Daniel K; Liu, Fu-Tong; Rothstein, Jeffrey D; Knoblach, Susan M

    2012-01-01

    Galectins are pleiotropic carbohydrate-binding lectins involved in inflammation, growth/differentiation, and tissue remodeling. The functional role of galectins in amyotrophic lateral sclerosis (ALS) is unknown. Expression studies revealed increases in galectin-1 mRNA and protein in spinal cords from SOD1G93A mice, and in galectin-3 and -9 mRNAs and proteins in spinal cords of both SOD1G93A mice and sporadic ALS patients. As the increase in galectin-3 appeared in early presymptomatic stages and increased progressively through to end stage of disease in the mouse, it was selected for additional study, where it was found to be mainly expressed by microglia. Galectin-3 antagonists are not selective and do not readily cross the blood–brain barrier; therefore, we generated SOD1G93A/Gal-3−/− transgenic mice to evaluate galectin-3 deletion in a widely used mouse model of ALS. Disease progression, neurological symptoms, survival, and inflammation were assessed to determine the effect of galectin-3 deletion on the SOD1G93A disease phenotype. Galectin-3 deletion did not change disease onset, but resulted in more rapid progression through functionally defined disease stages, more severely impaired neurological symptoms at all stages of disease, and expiration, on average, 25 days earlier than SOD1G93A/Gal-3+/+ cohorts. In addition, microglial staining, as well as TNF-α, and oxidative injury were increased in SOD1G93A/Gal-3−/− mice compared with SOD1G93A/Gal-3+/+ cohorts. These data support an important functional role for microglial galectin-3 in neuroinflammation during chronic neurodegenerative disease. We suggest that elevations in galectin-3 by microglia as disease progresses may represent a protective, anti-inflammatory innate immune response to chronic motor neuron degeneration. PMID:23139902

  9. Administration of 4-(α-L-Rhamnosyloxy)-benzyl Isothiocyanate Delays Disease Phenotype in SOD1G93A Rats: A Transgenic Model of Amyotrophic Lateral Sclerosis

    PubMed Central

    De Nicola, Gina Rosalinda; Mazzon, Emanuela

    2015-01-01

    4-(α-L-Rhamnosyloxy)-benzyl glucosinolate (glucomoringin, GMG) is a compound found in Moringa oleifera seeds. Myrosinase-catalyzed hydrolysis at neutral pH of GMG releases the biologically active compound 4-(α-L-rhamnosyloxy)-benzyl isothiocyanate (GMG-ITC). The present study was designed to test the potential therapeutic effectiveness of GMG-ITC to counteract the amyotrophic lateral sclerosis (ALS) using SOD1tg rats, which physiologically develops SOD1G93A at about 16 weeks of life, and can be considered a genetic model of disease. Rats were treated once a day with GMG (10 mg/Kg) bioactivated with myrosinase (20 µL/rat) via intraperitoneal (i.p.) injection for two weeks before disease onset and the treatment was prolonged for further two weeks before the sacrifice. Immune-inflammatory markers as well as apoptotic pathway were investigated to establish whether GMG-ITC could represent a new promising tool in clinical practice to prevent ALS. Achieved data display clear differences in molecular and biological profiles between treated and untreated SOD1tg rats leading to guessing that GMG-ITC can interfere with the pathophysiological mechanisms at the basis of ALS development. Therefore, GMG-ITC produced from myrosinase-catalyzed hydrolysis of pure GMG could be a candidate for further studies aimed to assess its possible use in clinical practice for the prevention or to slow down this disease. PMID:26075221

  10. Increased anxiety-like behavior and selective learning impairments are concomitant to loss of hippocampal interneurons in the presymptomatic SOD1(G93A) ALS mouse model.

    PubMed

    Quarta, Eros; Bravi, Riccardo; Scambi, Ilaria; Mariotti, Raffaella; Minciacchi, Diego

    2015-08-01

    Amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease primarily characterized by motor neuron death, causes damages beyond motor-related areas. In particular, cognitive impairments and hippocampal damage have been reported in ALS patients. We investigated spatial navigation learning and hippocampal interneurons in a mutant SOD1(G93A) mouse (mSOD1) model of ALS. Behavioral tests were performed by using presymptomatic mSOD1 mice. General motor activity was comparable to that of wild-type mice in the open-field test, in which, however mSOD1 exhibited increased anxiety-like behavior. In the Barnes maze test, mSOD1 mice displayed a delay in learning, outperformed wild-type mice during the first probe trial, and exhibited impaired long-term memory. Stereological counts of parvalbumin-positive interneurons, which are crucial for hippocampal physiology and known to be altered in other central nervous system regions of mSOD1 mice, were also performed. At postnatal day (P) 56, the population of parvalbumin-positive interneurons in mSOD1 mice was already reduced in CA1 and in CA3, and at P90 the reduction extended to the dentate gyrus. Loss of parvalbumin-positive hippocampal interneurons occurred mostly during the presymptomatic stage. Western blot analysis showed that hippocampal parvalbumin expression levels were already reduced in mSOD1 mice at P56. The hippocampal alterations in mSOD1 mice could at least partly account for the increased anxiety-like behavior and deficits in spatial navigation learning. Our study provides evidence for cognitive alterations and damage to the γ-aminobutyric acid (GABA)ergic system in the hippocampus of murine ALS, thereby revealing selective deficits antecedent to the onset of motor symptoms.

  11. Comparative morphometric analysis of microglia in the spinal cord of SOD1(G93A) transgenic mouse model of amyotrophic lateral sclerosis.

    PubMed

    Ohgomori, Tomohiro; Yamada, Jun; Takeuchi, Hideyuki; Kadomatsu, Kenji; Jinno, Shozo

    2016-05-01

    It has long been recognized that reactive microglia undergo a series of phenotypic changes accompanying morphological transformation. However, the morphological classification of microglia has not yet been achieved. To address this issue, here we morphometrically analysed three-dimensionally reconstructed ionized calcium binding adaptor molecule 1-immunoreactive (Iba1(+) ) microglia in the ventral horn of the lumbar spinal cord of SOD1(G93A) transgenic mice, a model of amyotrophic lateral sclerosis. The hierarchical cluster analysis revealed that microglia were objectively divided into four groups: type S (named after surveillant microglia) and types R1, R2 and R3 (named after reactive microglia). For the purpose of comparative morphometry, we also analysed two pharmacological disease models using wild-type mice: 3,3'-iminodipropionitrile (IDPN)-induced axonopathy and lipopolysaccharide (LPS)-induced neuroinflammation. Type S microglia showed a typical ramified morphology of surveillant microglia, and were mostly observed in wild-type controls. Type R1 microglia were seen at the early stage of disease in SOD1(G93A) mice, and also frequently occurred in IDPN-treated mice. They exhibited small cell bodies with shorter and simple processes. Type R2 microglia were morphologically similar to type R1 microglia, but only transiently occurred in the middle stage of disease in SOD1(G93A) mice and in IDPN-treated mice. Type R3 microglia exhibited a bushy shape, and were observed in the end stage of disease in SOD1(G93A) mice and in LPS-treated mice. These findings indicate that microglia of SOD1(G93A) mice can be classified into four types, and also suggest that the phenotypic changes may be induced by the events related to axonopathy and neuroinflammation. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  12. Dysregulation of the complement cascade in the hSOD1G93A transgenic mouse model of amyotrophic lateral sclerosis

    PubMed Central

    2013-01-01

    Background Components of the innate immune complement system have been implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS); however, a comprehensive examination of complement expression in this disease has not been performed. This study therefore aimed to determine the expression of complement components (C1qB, C4, factor B, C3/C3b, C5 and CD88) and regulators (CD55 and CD59a) in the lumbar spinal cord of hSOD1G93A mice during defined disease stages. Methods hSOD1G93A and wild-type mice were examined at four different ages of disease progression. mRNA and protein expression of complement components and regulators were examined using quantitative PCR, western blotting and ELISA. Localisation of complement components within lumbar spinal cord was investigated using immunohistochemistry. Statistical differences between hSOD1G93A and wild-type mice were analysed using a two-tailed t-test at each stage of disease progression. Results We found several early complement factors increased as disease progressed, whilst complement regulators decreased; suggesting overall increased complement activation through the classical or alternative pathways in hSOD1G93A mice. CD88 was also increased during disease progression, with immunolocalisation demonstrating expression on motor neurons and increasing expression on microglia surrounding the regions of motor neuron death. Conclusions These results indicate that local complement activation and increased expression of CD88 may contribute to motor neuron death and ALS pathology in the hSOD1G93A mouse. Hence, reducing complement-induced inflammation could be an important therapeutic strategy to treat ALS. PMID:24067070

  13. Lysosomal and phagocytic activity is increased in astrocytes during disease progression in the SOD1 G93A mouse model of amyotrophic lateral sclerosis

    PubMed Central

    Baker, David J.; Blackburn, Daniel J.; Keatinge, Marcus; Sokhi, Dilraj; Viskaitis, Paulius; Heath, Paul R.; Ferraiuolo, Laura; Kirby, Janine; Shaw, Pamela J.

    2015-01-01

    Astrocytes are key players in the progression of amyotrophic lateral sclerosis (ALS). Previously, gene expression profiling of astrocytes from the pre-symptomatic stage of the SOD1G93A model of ALS has revealed reduced lactate metabolism and altered trophic support. Here, we have performed microarray analysis of symptomatic and late-stage disease astrocytes isolated by laser capture microdissection (LCM) from the lumbar spinal cord of the SOD1G93A mouse to complete the picture of astrocyte behavior throughout the disease course. Astrocytes at symptomatic and late-stage disease show a distinct up-regulation of transcripts defining a reactive phenotype, such as those involved in the lysosome and phagocytic pathways. Functional analysis of hexosaminidase B enzyme activity in the spinal cord and of astrocyte phagocytic ability has demonstrated a significant increase in lysosomal enzyme activity and phagocytic activity in SOD1G93A vs. littermate controls, validating the findings of the microarray study. In addition to the increased reactivity seen at both stages, astrocytes from late-stage disease showed decreased expression of many transcripts involved in cholesterol homeostasis. Staining for the master regulator of cholesterol synthesis, SREBP2, has revealed an increased localization to the cytoplasm of astrocytes and motor neurons in late-stage SOD1G93A spinal cord, indicating that down-regulation of transcripts may be due to an excess of cholesterol in the CNS during late-stage disease possibly due to phagocytosis of neuronal debris. Our data reveal that SOD1G93A astrocytes are characterized more by a loss of supportive function than a toxic phenotype during ALS disease progression and future studies should focus upon restorative therapies. PMID:26528138

  14. Defining peripheral nervous system dysfunction in the SOD-1G93A transgenic rat model of amyotrophic lateral sclerosis.

    PubMed

    Riva, Nilo; Chaabane, Linda; Peviani, Marco; Ungaro, Daniela; Domi, Teuta; Dina, Giorgia; Bianchi, Francesca; Spano, Giorgia; Cerri, Federica; Podini, Paola; Corbo, Massimo; Carro, Ubaldo Del; Comi, Giancarlo; Bendotti, Caterina; Quattrini, Angelo

    2014-07-01

    Growing evidence indicates that alterations within the peripheral nervous system (PNS) are involved at an early stage in the amyotrophic lateral sclerosis (ALS) pathogenetic cascade. In this study, magnetic resonance imaging (MRI), neurophysiologic analyses, and histologic analyses were used to monitor the extent of PNS damage in the hSOD-1 ALS rat model. The imaging signature of the disease was defined using in vivo MRI of the sciatic nerve. Initial abnormalities were detected in the nerves by an increase in T2 relaxation time before the onset of clinical disease; diffusion MRI showed a progressive increase in mean and radial diffusivity and reduction of fractional anisotropy at advanced stages of disease. Histologic analysis demonstrated early impairment of the blood-nerve barrier followed by acute axonal degeneration associated with endoneurial edema and macrophage response in motor nerve compartments. Progressive axonal degeneration and motor nerve fiber loss correlated with MRI and neurophysiologic changes. These functional and morphologic investigations of the PNS might be applied in following disease progression in preclinical therapeutic studies. This study establishes the PNS signature in this rat ALS model (shedding new light into pathogenesis) and provides a rationale for translating into future systematic MRI studies of PNS involvement in patients with ALS.

  15. Fast skeletal muscle troponin activator tirasemtiv increases muscle function and performance in the B6SJL-SOD1G93A ALS mouse model.

    PubMed

    Hwee, Darren T; Kennedy, Adam; Ryans, Julie; Russell, Alan J; Jia, Zhiheng; Hinken, Aaron C; Morgans, David J; Malik, Fady I; Jasper, Jeffrey R

    2014-01-01

    Amyotrophic Lateral Sclerosis (ALS) is a motor neuron disease characterized by progressive motor neuron loss resulting in muscle atrophy, declining muscle function, and eventual paralysis. Patients typically die from respiratory failure 3 to 5 years from the onset of symptoms. Tirasemtiv is a fast skeletal troponin activator that sensitizes the sarcomere to calcium; this mechanism of action amplifies the response of muscle to neuromuscular input producing greater force when nerve input is reduced. Here, we demonstrate that a single dose of tirasemtiv significantly increases submaximal isometric force, forelimb grip strength, grid hang time, and rotarod performance in a female transgenic mouse model (B6SJL-SOD1 G93A) of ALS with functional deficits. Additionally, diaphragm force and tidal volume are significantly higher in tirasemtiv-treated female B6SJL-SOD1 G93A mice. These results support the potential of fast skeletal troponin activators to improve muscle function in neuromuscular diseases.

  16. Fast Skeletal Muscle Troponin Activator tirasemtiv Increases Muscle Function and Performance in the B6SJL-SOD1G93A ALS Mouse Model

    PubMed Central

    Ryans, Julie; Russell, Alan J.; Jia, Zhiheng; Hinken, Aaron C.; Morgans, David J.; Malik, Fady I.; Jasper, Jeffrey R.

    2014-01-01

    Amyotrophic Lateral Sclerosis (ALS) is a motor neuron disease characterized by progressive motor neuron loss resulting in muscle atrophy, declining muscle function, and eventual paralysis. Patients typically die from respiratory failure 3 to 5 years from the onset of symptoms. Tirasemtiv is a fast skeletal troponin activator that sensitizes the sarcomere to calcium; this mechanism of action amplifies the response of muscle to neuromuscular input producing greater force when nerve input is reduced. Here, we demonstrate that a single dose of tirasemtiv significantly increases submaximal isometric force, forelimb grip strength, grid hang time, and rotarod performance in a female transgenic mouse model (B6SJL-SOD1G93A) of ALS with functional deficits. Additionally, diaphragm force and tidal volume are significantly higher in tirasemtiv-treated female B6SJL-SOD1G93A mice. These results support the potential of fast skeletal troponin activators to improve muscle function in neuromuscular diseases. PMID:24805850

  17. Gene expression changes in spinal motoneurons of the SOD1G93A transgenic model for ALS after treatment with G-CSF

    PubMed Central

    Henriques, Alexandre; Kastner, Stefan; Chatzikonstantinou, Eva; Pitzer, Claudia; Plaas, Christian; Kirsch, Friederike; Wafzig, Oliver; Krüger, Carola; Spoelgen, Robert; Gonzalez De Aguilar, Jose-Luis; Gretz, Norbert; Schneider, Armin

    2015-01-01

    Background: Amyotrophic lateral sclerosis (ALS) is an incurable fatal motoneuron disease with a lifetime risk of approximately 1:400. It is characterized by progressive weakness, muscle wasting, and death ensuing 3–5 years after diagnosis. Granulocyte-colony stimulating factor (G-CSF) is a drug candidate for ALS, with evidence for efficacy from animal studies and interesting data from pilot clinical trials. To gain insight into the disease mechanisms and mode of action of G-CSF, we performed gene expression profiling on isolated lumbar motoneurons from SOD1G93A mice, the most frequently studied animal model for ALS, with and without G-CSF treatment. Results: Motoneurons from SOD1G93A mice present a distinct gene expression profile in comparison to controls already at an early disease stage (11 weeks of age), when treatment was initiated. The degree of deregulation increases at a time where motor symptoms are obvious (15 weeks of age). Upon G-CSF treatment, transcriptomic deregulations of SOD1G93A motoneurons were notably restored. Discriminant analysis revealed that SOD1 mice treated with G-CSF has a transcriptom close to presymptomatic SOD1 mice or wild type mice. Some interesting genes modulated by G-CSF treatment relate to neuromuscular function such as CCR4-NOT or Prss12. Conclusions: Our data suggest that G-CSF is able to re-adjust gene expression in symptomatic SOD1G93A motoneurons. This provides further arguments for G-CSF as a promising drug candidate for ALS. PMID:25653590

  18. Plasma Neurofilament Heavy Chain Levels Correlate to Markers of Late Stage Disease Progression and Treatment Response in SOD1G93A Mice that Model ALS

    PubMed Central

    Lu, Ching-Hua; Petzold, Axel; Kalmar, Bernadett; Dick, James; Malaspina, Andrea; Greensmith, Linda

    2012-01-01

    Background Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disorder characterised by progressive degeneration of motor neurons leading to death, typically within 3–5 years of symptom onset. The diagnosis of ALS is largely reliant on clinical assessment and electrophysiological findings. Neither specific investigative tools nor reliable biomarkers are currently available to enable an early diagnosis or monitoring of disease progression, hindering the design of treatment trials. Methodology/Principal Findings In this study, using the well-established SOD1G93A mouse model of ALS and a new in-house ELISA method, we have validated that plasma neurofilament heavy chain protein (NfH) levels correlate with both functional markers of late stage disease progression and treatment response. We detected a significant increase in plasma levels of phosphorylated NfH during disease progression in SOD1G93A mice from 105 days onwards. Moreover, increased plasma NfH levels correlated with the decline in muscle force, motor unit survival and, more significantly, with the loss of spinal motor neurons in SOD1 mice during this critical period of decline. Importantly, mice treated with the disease modifying compound arimoclomol had lower plasma NfH levels, suggesting plasma NfH levels could be validated as an outcome measure for treatment trials. Conclusions/Significance These results show that plasma NfH levels closely reflect later stages of disease progression and therapeutic response in the SOD1G93A mouse model of ALS and may potentially be a valuable biomarker of later disease progression in ALS. PMID:22815892

  19. Axonal degeneration, distal collateral branching and neuromuscular junction architecture alterations occur prior to symptom onset in the SOD1(G93A) mouse model of amyotrophic lateral sclerosis.

    PubMed

    Clark, Jayden A; Southam, Katherine A; Blizzard, Catherine A; King, Anna E; Dickson, Tracey C

    2016-10-01

    Degeneration of the distal axon and neuromuscular junction (NMJ) is considered a key and early feature of the pathology that accompanies motor neuron loss in people with amyotrophic lateral sclerosis (ALS). The mutant SOD1(G93A) mouse replicates many features of the disease, however the sequence of events resulting in degeneration of the neuromuscular circuitry remains unknown. Furthermore, despite widespread degenerative neuronal pathology throughout the spinal cord in this model, hindlimb motor function is lost before forelimb function. We investigated axons and NMJs in the hindlimb (gastrocnemius) and forelimb (extensor) muscles in the high copy number mutant SOD1(G93A)xYFP (yellow fluorescent protein) mouse. We found that distal axonal and NMJ alterations were present prior to previously reported functional symptom onset in this strain. Indeed, increased branch complexity as well as colocalisation between pre- and post-synaptic markers indicated widespread early axonal and NMJ alterations in the hindlimb. Immunohistochemical analysis demonstrated that the colocalisation of the scaffolding proteins nestin, LRP-4, dystrophin and rapsyn were diminished before post-synaptic receptors in the gastrocnemius, and the degree of loss differed between proteins. Analysis of the forelimb muscle revealed axonal and NMJ degeneration at a late, post symptomatic stage, as well as novel differences in NMJ morphology, with reduced complexity. Furthermore, post-synaptic scaffolding proteins were preserved in the forelimb compared with the hindlimb. Analysis of protein levels indicated an increase in LRP-4, dystrophin and rapsyn in post symptomatic skeletal muscle that may suggest ongoing attempts at repair. This study indicates that axonal and NMJ degeneration in the SOD1 model of ALS is a complex and evolving sequence of events. We provide evidence that YFP can detect morphological and plastic alterations in the SOD1(G93A) mouse, and that the pre- and post-synaptic integrity of

  20. Differential activation of neuronal and glial STAT3 in the spinal cord of the SOD1(G93A) mouse model of amyotrophic lateral sclerosis.

    PubMed

    Ohgomori, Tomohiro; Yamasaki, Ryo; Takeuchi, Hideyuki; Kadomatsu, Kenji; Kira, Jun-Ichi; Jinno, Shozo

    2017-08-01

    Signal transducer and activator of transcription (STAT) proteins are activated by phosphorylation in the spinal cord of patients suffering from amyotrophic lateral sclerosis (ALS). The major scope of our study is a comprehensive histological characterization of the mechanisms underlying neuronal and glial STAT3 activation in the pathogenesis of ALS using SOD1(G93A) mice. We calculated the fold changes (FCs, ratios vs. appropriate controls) of the numerical densities of the following phosphorylated STAT3-positive (pSTAT3)(+) cells - choline acetyltransferase (ChAT)(+) α-motoneurons, ionized calcium-binding adapter molecule 1 (Iba1)(+) microglia, and S100β(+) astrocytes in SOD1(G93A) mice. The FCs of pSTAT3(+) microglia and pSTAT3(+) astrocytes were increased from 9 to 15 weeks of age and then plateaued until 21 weeks. In contrast, the FCs of pSTAT3(+) α-motoneurons peaked at 9 weeks and then decreased until 21 weeks. The immunoreactivity for nonphosphorylated neurofilament protein (SMI-32), a marker of axonal impairment, was decreased in pSTAT3(+) α-motoneurons compared with pSTAT3(-) α-motoneurons at 9 weeks of age. We then compared the following pharmacological models - the chronic administration of 3,3'-iminodipropionitrile (IDPN), which models axonal impairment, and the acute administration of lipopolysaccharide (LPS), which is a model of neuroinflammation. The FCs of pSTAT3(+) α-motoneurons were increased in IDPN-treated mice, while those of pSTAT3(+) microglia were increased in LPS-treated mice. The FCs of pSTAT3(+) astrocytes were higher in SOD1(G93A) mice at 9 weeks compared with IDPN- and LPS-treated mice. Our results indicate that axonopathy and neuroinflammation may trigger the respective activation of neuronal and glial STAT3, which is observed during ALS pathogenesis. © 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  1. In vivo EPR pharmacokinetic evaluation of the redox status and the blood brain barrier permeability in the SOD1(G93A) ALS rat model.

    PubMed

    Stamenković, Stefan; Pavićević, Aleksandra; Mojović, Miloš; Popović-Bijelić, Ana; Selaković, Vesna; Andjus, Pavle; Bačić, Goran

    2017-03-31

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder affecting the motor pathways of the central nervous system. Although a number of pathophysiological mechanisms have been described in the disease, post mortem and animal model studies indicate blood-brain barrier (BBB) disruption and elevated production of reactive oxygen species as major contributors to disease pathology. In this study, the BBB permeability and the brain tissue redox status of the SOD1(G93A) ALS rat model in the presymptomatic (preALS) and symptomatic (ALS) stages of the disease were investigated by in vivo EPR spectroscopy using three aminoxyl radicals with different cell membrane and BBB permeabilities, Tempol, 3-carbamoyl proxyl (3CP), and 3-carboxy proxyl (3CxP). Additionally, the redox status of the two brain regions previously implicated in disease pathology, brainstem and hippocampus, was investigated by spectrophotometric biochemical assays. The EPR results indicated that among the three spin probes, 3CP is the most suitable for reporting the intracellular redox status changes, as Tempol was reduced in vivo within minutes (t1/2 =2.0±0.5min), thus preventing reliable kinetic modeling, whereas 3CxP reduction kinetics gave divergent conclusions, most probably due to its membrane impermeability. It was observed that the reduction kinetics of 3CP in vivo, in the head of preALS and ALS SOD1(G93A) rats was altered compared to the controls. Pharmacokinetic modeling of 3CP reduction in vivo, revealed elevated tissue distribution and tissue reduction rate constants indicating an altered brain tissue redox status, and possibly BBB disruption in these animals. The preALS and ALS brain tissue homogenates also showed increased nitrilation, superoxide production, lipid peroxidation and manganese superoxide dismutase activity, and a decreased copper-zinc superoxide dismutase activity. The present study highlights in vivo EPR spectroscopy as a reliable tool for the investigation of

  2. Calretinin and Neuropeptide Y interneurons are differentially altered in the motor cortex of the SOD1G93A mouse model of ALS

    PubMed Central

    Clark, Rosemary M.; Blizzard, Catherine A.; Young, Kaylene M.; King, Anna E.; Dickson, Tracey C.

    2017-01-01

    Increasing evidence indicates an excitatory/inhibitory imbalance may have a critical role in the pathogenesis of amyotrophic lateral sclerosis (ALS). Impaired inhibitory circuitry is consistently reported in the motor cortex of both familial and sporadic patients, closely associated with cortical hyperexcitability and ALS onset. Inhibitory network dysfunction is presumably mediated by intra-cortical inhibitory interneurons, however, the exact cell types responsible are yet to be identified. In this study we demonstrate dynamic changes in the number of calretinin- (CR) and neuropeptide Y-expressing (NPY) interneurons in the motor cortex of the familial hSOD1G93A ALS mouse model, suggesting their potential involvement in motor neuron circuitry defects. We show that the density of NPY-populations is significantly decreased by ~17% at symptom onset (8 weeks), and by end-stage disease (20 weeks) is significantly increased by ~30%. Conversely, the density of CR-populations is progressively reduced during later symptomatic stages (~31%) to end-stage (~36%), while CR-expressing interneurons also show alteration of neurite branching patterns at symptom onset. We conclude that a differential capacity for interneurons exists in the ALS motor cortex, which may not be a static phenomenon, but involves early dynamic changes throughout disease, implicating specific inhibitory circuitry. PMID:28294153

  3. Downregulation of Homer1b/c in SOD1 G93A Models of ALS: A Novel Mechanism of Neuroprotective Effect of Lithium and Valproic Acid.

    PubMed

    Jiang, Hai-Zhi; Wang, Shu-Yu; Yin, Xiang; Jiang, Hong-Quan; Wang, Xu-Dong; Wang, Jing; Wang, Tian-Hang; Qi, Yan; Yang, Yue-Qing; Wang, Ying; Zhang, Chun-Ting; Feng, Hong-Lin

    2016-12-17

    Mutations in the Cu/Zn superoxide dismutase (SOD1) gene have been linked to amyotrophic lateral sclerosis (ALS). However, the molecular mechanisms have not been elucidated yet. Homer family protein Homer1b/c is expressed widely in the central nervous system and plays important roles in neurological diseases. In this study, we explored whether Homer1b/c was involved in SOD1 mutation-linked ALS. In vitro studies showed that the SOD1 G93A mutation induced an increase of Homer1b/c expression at both the mRNA and protein levels in NSC34 cells. Knockdown of Homer1b/c expression using its short interfering RNA (siRNA) (si-Homer1) protected SOD1 G93A NSC34 cells from apoptosis. The expressions of Homer1b/c and apoptosis-related protein Bax were also suppressed, while Bcl-2 was increased by lithium and valproic acid (VPA) in SOD1 G93A NSC34 cells. In vivo, both the mRNA and protein levels of Homer1b/c were increased significantly in the lumbar spinal cord in SOD1 G93A transgenic mice compared with wild type (WT) mice. Moreover, lithium and VPA treatment suppressed the expression of Homer1b/c in SOD1 G93A mice. The suppression of SOD1 G93A mutation-induced Homer1b/c upregulation protected ALS against neuronal apoptosis, which is a novel mechanism of the neuroprotective effect of lithium and VPA. This study provides new insights into pathogenesis and treatment of ALS.

  4. Downregulation of Homer1b/c in SOD1 G93A Models of ALS: A Novel Mechanism of Neuroprotective Effect of Lithium and Valproic Acid

    PubMed Central

    Jiang, Hai-Zhi; Wang, Shu-Yu; Yin, Xiang; Jiang, Hong-Quan; Wang, Xu-Dong; Wang, Jing; Wang, Tian-Hang; Qi, Yan; Yang, Yue-Qing; Wang, Ying; Zhang, Chun-Ting; Feng, Hong-Lin

    2016-01-01

    Background: Mutations in the Cu/Zn superoxide dismutase (SOD1) gene have been linked to amyotrophic lateral sclerosis (ALS). However, the molecular mechanisms have not been elucidated yet. Homer family protein Homer1b/c is expressed widely in the central nervous system and plays important roles in neurological diseases. In this study, we explored whether Homer1b/c was involved in SOD1 mutation-linked ALS. Results: In vitro studies showed that the SOD1 G93A mutation induced an increase of Homer1b/c expression at both the mRNA and protein levels in NSC34 cells. Knockdown of Homer1b/c expression using its short interfering RNA (siRNA) (si-Homer1) protected SOD1 G93A NSC34 cells from apoptosis. The expressions of Homer1b/c and apoptosis-related protein Bax were also suppressed, while Bcl-2 was increased by lithium and valproic acid (VPA) in SOD1 G93A NSC34 cells. In vivo, both the mRNA and protein levels of Homer1b/c were increased significantly in the lumbar spinal cord in SOD1 G93A transgenic mice compared with wild type (WT) mice. Moreover, lithium and VPA treatment suppressed the expression of Homer1b/c in SOD1 G93A mice. Conclusion: The suppression of SOD1 G93A mutation-induced Homer1b/c upregulation protected ALS against neuronal apoptosis, which is a novel mechanism of the neuroprotective effect of lithium and VPA. This study provides new insights into pathogenesis and treatment of ALS. PMID:27999308

  5. Influence of Methylene Blue on Microglia-Induced Inflammation and Motor Neuron Degeneration in the SOD1G93A Model for ALS

    PubMed Central

    Steffens, Heinz; Scheffel, Jörg; Göricke, Bettina; Weishaupt, Jochen H.; Le Meur, Karim; Kirchhoff, Frank; Hanisch, Uwe-Karsten; Schomburg, Eike D.; Neusch, Clemens

    2012-01-01

    Mutations in SOD1 cause hereditary variants of the fatal motor neuron disease amyotrophic lateral sclerosis (ALS). Pathophysiology of the disease is non-cell-autonomous, with toxicity deriving also from glia. In particular, microglia contribute to disease progression. Methylene blue (MB) inhibits the effect of nitric oxide, which mediates microglial responses to injury. In vivo 2P-LSM imaging was performed in ALS-linked transgenic SOD1G93A mice to investigate the effect of MB on microglia-mediated inflammation in the spinal cord. Local superfusion of the lateral spinal cord with MB inhibited the microglial reaction directed at a laser-induced axon transection in control and SOD1G93A mice. In vitro, MB at high concentrations inhibited cytokine and chemokine release from microglia of control and advanced clinical SOD1G93A mice. Systemic MB-treatment of SOD1G93A mice at early preclinical stages significantly delayed disease onset and motor dysfunction. However, an increase of MB dose had no additional effect on disease progression; this was unexpected in view of the local anti-inflammatory effects. Furthermore, in vivo imaging of systemically MB-treated mice also showed no alterations of microglia activity in response to local lesions. Thus although systemic MB treatment had no effect on microgliosis, instead, its use revealed an important influence on motor neuron survival as indicated by an increased number of lumbar anterior horn neurons present at the time of disease onset. Thus, potentially beneficial effects of locally applied MB on inflammatory events contributing to disease progression could not be reproduced in SOD1G93A mice via systemic administration, whereas systemic MB application delayed disease onset via neuroprotection. PMID:22952827

  6. Death receptor 6 (DR6) antagonist antibody is neuroprotective in the mouse SOD1G93A model of amyotrophic lateral sclerosis

    PubMed Central

    Huang, G; Lee, X; Bian, Y; Shao, Z; Sheng, G; Pepinsky, R B; Mi, S

    2013-01-01

    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the death of motor neurons, axon degeneration, and denervation of neuromuscular junctions (NMJ). Here we show that death receptor 6 (DR6) levels are elevated in spinal cords from post-mortem samples of human ALS and from SOD1G93A transgenic mice, and DR6 promotes motor neuron death through activation of the caspase 3 signaling pathway. Blocking DR6 with antagonist antibody 5D10 promotes motor neuron survival in vitro via activation of Akt phosphorylation and inhibition of the caspase 3 signaling pathway, after growth factor withdrawal, sodium arsenite treatment or co-culture with SOD1G93A astrocytes. Treatment of SOD1G93A mice at an asymptomatic stage starting on the age of 42 days with 5D10 protects NMJ from denervation, decreases gliosis, increases survival of motor neurons and CC1+ oligodendrocytes in spinal cord, decreases phosphorylated neurofilament heavy chain (pNfH) levels in serum, and promotes motor functional improvement assessed by increased grip strength. The combined data provide clear evidence for neuroprotective effects of 5D10. Blocking DR6 function represents a new approach for the treatment of neurodegenerative disorders involving motor neuron death and axon degeneration, such as ALS. PMID:24113175

  7. State of the field: An informatics-based systematic review of the SOD1-G93A amyotrophic lateral sclerosis transgenic mouse model

    PubMed Central

    Kim, Renaid B.; Irvin, Cameron W.; Tilva, Keval R.; Mitchell, Cassie S.

    2016-01-01

    Numerous sub-cellular through system-level disturbances have been identified in over 1300 articles examining the superoxide dismutase-1 guanine 93 to alanine (SOD1-G93A) transgenic mouse amyotrophic lateral sclerosis (ALS) pathophysiology. Manual assessment of such a broad literature base is daunting. We performed a comprehensive informatics-based systematic review or ‘field analysis’ to agnostically compute and map the current state of the field. Text mining of recaptured articles was used to quantify published data topic breadth and frequency. We constructed a nine-category pathophysiological function-based ontology to systematically organize and quantify the field's primary data. Results demonstrated that the distribution of primary research belonging to each category is: systemic measures an motor function, 59%; inflammation, 46%; cellular energetics, 37%; proteomics, 31%; neural excitability, 22%; apoptosis, 20%; oxidative stress, 18%; aberrant cellular chemistry, 14%; axonal transport, 10%. We constructed a SOD1-G93A field map that visually illustrates and categorizes the 85% most frequently assessed sub-topics. Finally, we present the literature-cited significance of frequently published terms and uncover thinly investigated areas. In conclusion, most articles individually examine at least two categories, which is indicative of the numerous underlying pathophysiological interrelationships. An essential future path is examination of cross-category pathophysiological interrelationships and their co-correspondence to homeostatic regulation and disease progression. PMID:25998063

  8. Rho Kinase Inhibition with Fasudil in the SOD1G93A Mouse Model of Amyotrophic Lateral Sclerosis—Symptomatic Treatment Potential after Disease Onset

    PubMed Central

    Günther, René; Balck, Alexander; Koch, Jan C.; Nientiedt, Tobias; Sereda, Michael; Bähr, Mathias; Lingor, Paul; Tönges, Lars

    2017-01-01

    Despite an improved understanding of the genetic background and the pathomechanisms of amyotrophic lateral sclerosis (ALS) no novel disease-modifying therapies have been successfully implemented in clinical routine. Riluzole still remains the only clinically approved substance in human ALS treatment with limited efficacy. We have previously identified pharmacological rho kinase (ROCK) inhibitors as orally applicable substances in SOD1.G93A transgenic ALS mice (SOD1G93A), which are able to extend survival time and improve motor function after presymptomatic treatment. Here, we have evaluated the therapeutic effect of the orally administered ROCK inhibitor Fasudil starting at a symptomatic disease stage, more realistically reflecting the clinical situation. Oral Fasudil treatment was initiated at a symptomatic stage at 80 days of life (d80) with 30 or 100 mg/kg body weight in both female and male mice. While baseline neurological scoring and survival were not influenced, Fasudil significantly improved motor behavior in male mice. Spinal cord pathology of motoneurons (MN) and infiltrating microglial cells (MG) at disease end-stage were not significantly modified. Although treatment after symptom onset was less potent than treatment in asymptomatic animals, our study shows the therapeutic benefits of this well-tolerated substance, which is already in clinical use for other indications. PMID:28197100

  9. State of the field: An informatics-based systematic review of the SOD1-G93A amyotrophic lateral sclerosis transgenic mouse model.

    PubMed

    Kim, Renaid B; Irvin, Cameron W; Tilva, Keval R; Mitchell, Cassie S

    2015-01-01

    Numerous sub-cellular through system-level disturbances have been identified in over 1300 articles examining the superoxide dismutase-1 guanine 93 to alanine (SOD1-G93A) transgenic mouse amyotrophic lateral sclerosis (ALS) pathophysiology. Manual assessment of such a broad literature base is daunting. We performed a comprehensive informatics-based systematic review or 'field analysis' to agnostically compute and map the current state of the field. Text mining of recaptured articles was used to quantify published data topic breadth and frequency. We constructed a nine-category pathophysiological function-based ontology to systematically organize and quantify the field's primary data. Results demonstrated that the distribution of primary research belonging to each category is: systemic measures an motor function, 59%; inflammation, 46%; cellular energetics, 37%; proteomics, 31%; neural excitability, 22%; apoptosis, 20%; oxidative stress, 18%; aberrant cellular chemistry, 14%; axonal transport, 10%. We constructed a SOD1-G93A field map that visually illustrates and categorizes the 85% most frequently assessed sub-topics. Finally, we present the literature-cited significance of frequently published terms and uncover thinly investigated areas. In conclusion, most articles individually examine at least two categories, which is indicative of the numerous underlying pathophysiological interrelationships. An essential future path is examination of cross-category pathophysiological interrelationships and their co-correspondence to homeostatic regulation and disease progression.

  10. Metformin treatment has no beneficial effect in a dose-response survival study in the SOD1(G93A) mouse model of ALS and is harmful in female mice.

    PubMed

    Kaneb, Hannah M; Sharp, Paul S; Rahmani-Kondori, Nazanin; Wells, Dominic J

    2011-01-01

    Amyotrophic Lateral Sclerosis (ALS) is a devastating neurological disorder characterized by selective degeneration of upper and lower motor neurons. The primary triggers for motor neuron degeneration are unknown but inflammation, oxidative stress and mitochondrial defects have been identified as potential contributing factors. Metformin is an anti-type II diabetes drug that has anti-inflammatory and anti-oxidant properties, can bring about mitochondrial biogenesis and has been shown to attenuate pathology in mouse models of Huntington's disease and multiple sclerosis. We therefore hypothesized that it might increase survival in the SOD1(G93A) murine model of ALS. Treatment of male and female SOD1(G93A) mice (n = ≥6 per sex) with 2 mg/ml metformin in the drinking water from 35 days, resulted in a significant increase in motor unit survival, as measured by in vivo electrophysiology at 100 days, in male EDL muscles (24+/-2 vs. 14+/-2 motor units, p<0.005) and female TA muscles (21+/-1 vs. 15+/-2 motor units, P = 0.0134). We therefore continued to test the effect of 0.5, 2 and 5 mg/ml metformin in the drinking water from 35 days on disease onset and progression (identified by twice weekly determination of weight and neurological score) as well as survival in male and female SOD1(G93A) mice (n = ≥14 per sex). Results for all groups were compared using Kaplan-Meier time to event analyses. In this survival study, metformin was unable to reduce pathology at any dose and had an unexpected dose-dependent negative effect on the onset of neurological symptoms (P = 0.0236) and on disease progression (P = 0.0362) in female mice. This study suggests that metformin is a poor candidate for clinical trial in ALS patients and that the possibility of harmful effects of metformin in female ALS patients with type II diabetes should be investigated.

  11. Metformin Treatment Has No Beneficial Effect in a Dose-Response Survival Study in the SOD1G93A Mouse Model of ALS and Is Harmful in Female Mice

    PubMed Central

    Kaneb, Hannah M.; Sharp, Paul S.; Rahmani-Kondori, Nazanin; Wells, Dominic J.

    2011-01-01

    Background Amyotrophic Lateral Sclerosis (ALS) is a devastating neurological disorder characterized by selective degeneration of upper and lower motor neurons. The primary triggers for motor neuron degeneration are unknown but inflammation, oxidative stress and mitochondrial defects have been identified as potential contributing factors. Metformin is an anti-type II diabetes drug that has anti-inflammatory and anti-oxidant properties, can bring about mitochondrial biogenesis and has been shown to attenuate pathology in mouse models of Huntington's disease and multiple sclerosis. We therefore hypothesized that it might increase survival in the SOD1G93A murine model of ALS. Methodology/Principal Findings Treatment of male and female SOD1G93A mice (n = ≥6 per sex) with 2 mg/ml metformin in the drinking water from 35 days, resulted in a significant increase in motor unit survival, as measured by in vivo electrophysiology at 100 days, in male EDL muscles (24+/−2 vs. 14+/−2 motor units, p<0.005) and female TA muscles (21+/−1 vs. 15+/−2 motor units, P = 0.0134). We therefore continued to test the effect of 0.5, 2 and 5 mg/ml metformin in the drinking water from 35 days on disease onset and progression (identified by twice weekly determination of weight and neurological score) as well as survival in male and female SOD1G93A mice (n = ≥14 per sex). Results for all groups were compared using Kaplan-Meier time to event analyses. In this survival study, metformin was unable to reduce pathology at any dose and had an unexpected dose-dependent negative effect on the onset of neurological symptoms (P = 0.0236) and on disease progression (P = 0.0362) in female mice. Conclusions/Significance This study suggests that metformin is a poor candidate for clinical trial in ALS patients and that the possibility of harmful effects of metformin in female ALS patients with type II diabetes should be investigated. PMID:21909419

  12. Treatment with a coinducer of the heat shock response delays muscle denervation in the SOD1-G93A mouse model of amyotrophic lateral sclerosis.

    PubMed

    Kalmar, Bernadett; Edet-Amana, Emem; Greensmith, Linda

    2012-06-01

    We undertook a longitudinal study of the histological and biochemical changes at the neuromuscular junction (NMJ) in muscles of SOD1-G93A mice. We also assessed these functions in mice treated with a known heat shock protein inducer, arimoclomol. Tissue samples of treated and untreated mSOD mice were analysed for AChE and ChAT enzyme activities as markers of neuromuscular function. Sections of hindlimb muscles (TA, EDL and soleus) were also stained for succinate dehydrogenase and silver cholinesterase activities as well as for immunohistochemistry. Hsp70 levels were also measured from muscle samples using ELISA. Results showed that denervation and nerve sprouting were present at symptom onset in fast muscles, although slow muscles remained fully innervated. Cholinergic enzyme activities were reduced prior to denervation and declined further with disease progression. Reduction of endplate size, a slow to fast shift in muscle phenotype was also observed. Treatment with arimoclomol delayed the appearance of these changes, increased innervation, cholinergic enzyme activities and endplate size and reversed muscle fibre transformation. These beneficial effects of arimoclomol in muscles were accompanied by an increase in Hsp70 expression. In conclusion, our results indicate that pharmacological targeting of muscles at early stages of disease may be a successful strategy to ameliorate disease progression in ALS.

  13. Dysregulated expression of death, stress and mitochondrion related genes in the sciatic nerve of presymptomatic SOD1G93A mouse model of Amyotrophic Lateral Sclerosis

    PubMed Central

    Alves, Chrystian J.; Maximino, Jessica R.; Chadi, Gerson

    2015-01-01

    Schwann cells are the main source of paracrine support to motor neurons. Oxidative stress and mitochondrial dysfunction have been correlated to motor neuron death in Amyotrophic Lateral Sclerosis (ALS). Despite the involvement of Schwann cells in early neuromuscular disruption in ALS, detailed molecular events of a dying-back triggering are unknown. Sciatic nerves of presymptomatic (60-day-old) SOD1G93A mice were submitted to a high-density oligonucleotide microarray analysis. DAVID demonstrated the deregulated genes related to death, stress and mitochondrion, which allowed the identification of Cell cycle, ErbB signaling, Tryptophan metabolism and Rig-I-like receptor signaling as the most representative KEGG pathways. The protein-protein interaction networks based upon deregulated genes have identified the top hubs (TRAF2, H2AFX, E2F1, FOXO3, MSH2, NGFR, TGFBR1) and bottlenecks (TRAF2, E2F1, CDKN1B, TWIST1, FOXO3). Schwann cells were enriched from the sciatic nerve of presymptomatic mice using flow cytometry cell sorting. qPCR showed the up regulated (Ngfr, Cdnkn1b, E2f1, Traf2 and Erbb3, H2afx, Cdkn1a, Hspa1, Prdx, Mapk10) and down-regulated (Foxo3, Mtor) genes in the enriched Schwann cells. In conclusion, molecular analyses in the presymptomatic sciatic nerve demonstrated the involvement of death, oxidative stress, and mitochondrial pathways in the Schwann cell non-autonomous mechanisms in the early stages of ALS. PMID:26339226

  14. Depressed excitability and ion currents linked to slow exocytotic fusion pore in chromaffin cells of the SOD1(G93A) mouse model of amyotrophic lateral sclerosis.

    PubMed

    Calvo-Gallardo, Enrique; de Pascual, Ricardo; Fernández-Morales, José-Carlos; Arranz-Tagarro, Juan-Alberto; Maroto, Marcos; Nanclares, Carmen; Gandía, Luis; de Diego, Antonio M G; Padín, Juan-Fernando; García, Antonio G

    2015-01-01

    Altered synaptic transmission with excess glutamate release has been implicated in the loss of motoneurons occurring in amyotrophic lateral sclerosis (ALS). Hyperexcitability or hypoexcitability of motoneurons from mice carrying the ALS mutation SOD1(G93A) (mSOD1) has also been reported. Here we have investigated the excitability, the ion currents, and the kinetics of the exocytotic fusion pore in chromaffin cells from postnatal day 90 to postnatal day 130 mSOD1 mice, when motor deficits are already established. With respect to wild-type (WT), mSOD1 chromaffin cells had a decrease in the following parameters: 95% in spontaneous action potentials, 70% in nicotinic current for acetylcholine (ACh), 35% in Na(+) current, 40% in Ca(2+)-dependent K(+) current, and 53% in voltage-dependent K(+) current. Ca(2+) current was increased by 37%, but the ACh-evoked elevation of cytosolic Ca(2+) was unchanged. Single exocytotic spike events triggered by ACh had the following differences (mSOD1 vs. WT): 36% lower rise rate, 60% higher decay time, 51% higher half-width, 13% lower amplitude, and 61% higher quantal size. The expression of the α3-subtype of nicotinic receptors and proteins of the exocytotic machinery was unchanged in the brain and adrenal medulla of mSOD1, with respect to WT mice. A slower fusion pore opening, expansion, and closure are likely linked to the pronounced reduction in cell excitability and in the ion currents driving action potentials in mSOD1, compared with WT chromaffin cells.

  15. Voyager Development Test Model

    NASA Image and Video Library

    2017-07-05

    This archival photo shows the encapsulation of the Voyager Development Test Model at NASA's Kennedy Space Center's Eastern Test Range. The picture was taken on October 8, 1976. https://photojournal.jpl.nasa.gov/catalog/PIA21730

  16. Voyager Development Test Model

    NASA Image and Video Library

    2017-07-05

    This archival photo shows the encapsulation of the Voyager Development Test Model at NASA's Kennedy Space Center's Eastern Test Range. The picture was taken on October 8, 1976. https://photojournal.jpl.nasa.gov/catalog/PIA21731

  17. A comprehensive assessment of the SOD1G93A low-copy transgenic mouse, which models human amyotrophic lateral sclerosis.

    PubMed

    Acevedo-Arozena, Abraham; Kalmar, Bernadett; Essa, Shafa; Ricketts, Thomas; Joyce, Peter; Kent, Rosie; Rowe, Claire; Parker, Andy; Gray, Anna; Hafezparast, Majid; Thorpe, Julian R; Greensmith, Linda; Fisher, Elizabeth M C

    2011-09-01

    Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder that results in the death of motor neurons in the brain and spinal cord. The disorder generally strikes in mid-life, relentlessly leading to paralysis and death, typically 3-5 years after diagnosis. No effective treatments are available. Up to 10% of ALS is familial, usually autosomal dominant. Several causative genes are known and, of these, mutant superoxide dismutase 1 (SOD1) is by far the most frequently found, accounting for up to 20% of familial ALS. A range of human mutant SOD1 transgenic mouse strains has been produced, and these largely successfully model the human disease. Of these, the most widely used is the SOD1 mouse, which expresses a human SOD1 transgene with a causative G93A mutation. This mouse model is excellent for many purposes but carries up to 25 copies of the transgene and produces a great excess of SOD1 protein, which might affect our interpretation of disease processes. A variant of this strain carries a deletion of the transgene array such that the copy number is dropped to eight to ten mutant SOD1 genes. This 'deleted' 'low-copy' mouse undergoes a slower course of disease, over many months. Here we have carried out a comprehensive analysis of phenotype, including nerve and muscle physiology and histology, to add to our knowledge of this 'deleted' strain and give baseline data for future studies. We find differences in phenotype that arise from genetic background and sex, and we quantify the loss of nerve and muscle function over time. The slowly progressive pathology observed in this mouse strain could provide us with a more appropriate model for studying early-stage pathological processes in ALS and aid the development of therapies for early-stage treatments.

  18. INaP selective inhibition reverts precocious inter- and motorneurons hyperexcitability in the Sod1-G93R zebrafish ALS model

    PubMed Central

    Benedetti, Lorena; Ghilardi, Anna; Rottoli, Elsa; De Maglie, Marcella; Prosperi, Laura; Perego, Carla; Baruscotti, Mirko; Bucchi, Annalisa; Del Giacco, Luca; Francolini, Maura

    2016-01-01

    The pathogenic role of SOD1 mutations in amyotrophic lateral sclerosis (ALS) was investigated using a zebrafish disease model stably expressing the ALS-linked G93R mutation. In addition to the main pathological features of ALS shown by adult fish, we found remarkably precocious alterations in the development of motor nerve circuitry and embryo behavior, and suggest that these alterations are prompted by interneuron and motor neuron hyperexcitability triggered by anomalies in the persistent pacemaker sodium current INaP. The riluzole-induced modulation of INaP reduced spinal neuron excitability, reverted the behavioral phenotypes and improved the deficits in motor nerve circuitry development, thus shedding new light on the use of riluzole in the management of ALS. Our findings provide a valid phenotype-based tool for unbiased in vivo drug screening that can be used to develop new therapies. PMID:27079797

  19. INaP selective inhibition reverts precocious inter- and motorneurons hyperexcitability in the Sod1-G93R zebrafish ALS model.

    PubMed

    Benedetti, Lorena; Ghilardi, Anna; Rottoli, Elsa; De Maglie, Marcella; Prosperi, Laura; Perego, Carla; Baruscotti, Mirko; Bucchi, Annalisa; Del Giacco, Luca; Francolini, Maura

    2016-04-15

    The pathogenic role of SOD1 mutations in amyotrophic lateral sclerosis (ALS) was investigated using a zebrafish disease model stably expressing the ALS-linked G93R mutation. In addition to the main pathological features of ALS shown by adult fish, we found remarkably precocious alterations in the development of motor nerve circuitry and embryo behavior, and suggest that these alterations are prompted by interneuron and motor neuron hyperexcitability triggered by anomalies in the persistent pacemaker sodium current INaP. The riluzole-induced modulation of INaP reduced spinal neuron excitability, reverted the behavioral phenotypes and improved the deficits in motor nerve circuitry development, thus shedding new light on the use of riluzole in the management of ALS. Our findings provide a valid phenotype-based tool for unbiased in vivo drug screening that can be used to develop new therapies.

  20. Phenotypic heterogeneity in a SOD1 G93D Italian ALS family: an example of human model to study a complex disease.

    PubMed

    Penco, Silvana; Lunetta, Christian; Mosca, Lorena; Maestri, Eleonora; Avemaria, Francesca; Tarlarini, Claudia; Patrosso, Maria Cristina; Marocchi, Alessandro; Corbo, Massimo

    2011-05-01

    We report different clinical expression in seven members of a large family with amyotrophic lateral sclerosis (ALS) and the G93D mutation in exon 4 of the Cu/Zn superoxide dismutase (SOD1) gene. The ALS clinical course in the proband showed an unusually fast progression of the disease compared to the paucisymptomatic presentation associated to this mutation in the two previously Italian families described. The remaining mutation carriers did not show the aggressive clinical course displayed by the proband. We selected few genes known to be ALS modifiers searching for genetic variants that could explain the wide phenotypic diversity within the family. Exclusion of causative genes such as TDP43, FUS, PGRN and VAPB was performed too. We believe that this kind of family with contrasting phenotypes of ALS may be considered an excellent human model to study the relationship between a wider genetic profile, including modifier genes, and the clinical expression of the disease. Therefore, the novelty of our approach is also represented by the study of a single family to reproduce a composite structure in which search for possible modifier genes/genetic variants linked to SOD1 mutated.

  1. Earthquake likelihood model testing

    USGS Publications Warehouse

    Schorlemmer, D.; Gerstenberger, M.C.; Wiemer, S.; Jackson, D.D.; Rhoades, D.A.

    2007-01-01

    INTRODUCTIONThe Regional Earthquake Likelihood Models (RELM) project aims to produce and evaluate alternate models of earthquake potential (probability per unit volume, magnitude, and time) for California. Based on differing assumptions, these models are produced to test the validity of their assumptions and to explore which models should be incorporated in seismic hazard and risk evaluation. Tests based on physical and geological criteria are useful but we focus on statistical methods using future earthquake catalog data only. We envision two evaluations: a test of consistency with observed data and a comparison of all pairs of models for relative consistency. Both tests are based on the likelihood method, and both are fully prospective (i.e., the models are not adjusted to fit the test data). To be tested, each model must assign a probability to any possible event within a specified region of space, time, and magnitude. For our tests the models must use a common format: earthquake rates in specified “bins” with location, magnitude, time, and focal mechanism limits.Seismology cannot yet deterministically predict individual earthquakes; however, it should seek the best possible models for forecasting earthquake occurrence. This paper describes the statistical rules of an experiment to examine and test earthquake forecasts. The primary purposes of the tests described below are to evaluate physical models for earthquakes, assure that source models used in seismic hazard and risk studies are consistent with earthquake data, and provide quantitative measures by which models can be assigned weights in a consensus model or be judged as suitable for particular regions.In this paper we develop a statistical method for testing earthquake likelihood models. A companion paper (Schorlemmer and Gerstenberger 2007, this issue) discusses the actual implementation of these tests in the framework of the RELM initiative.Statistical testing of hypotheses is a common task and a

  2. Acoustic Model Testing Chronology

    NASA Technical Reports Server (NTRS)

    Nesman, Tom

    2017-01-01

    Scale models have been used for decades to replicate liftoff environments and in particular acoustics for launch vehicles. It is assumed, and analyses supports, that the key characteristics of noise generation, propagation, and measurement can be scaled. Over time significant insight was gained not just towards understanding the effects of thruster details, pad geometry, and sound mitigation but also to the physical processes involved. An overview of a selected set of scale model tests are compiled here to illustrate the variety of configurations that have been tested and the fundamental knowledge gained. The selected scale model tests are presented chronologically.

  3. Voyager Test Model Configuration

    NASA Image and Video Library

    2017-07-05

    This archival photo shows the Voyager proof test model, which did not fly in space, in the 25-foot space simulator chamber at NASA's Jet Propulsion Laboratory on December 3, 1976. https://photojournal.jpl.nasa.gov/catalog/PIA21735

  4. Voyager Proof Test Model

    NASA Image and Video Library

    1977-01-12

    This archival photo shows the Voyager Proof Test Model undergoing a mechanical preparation and weight center of gravity test at NASA's Jet Propulsion Laboratory, Pasadena, California, on January 12, 1977. The stack of three white cylinders seen near center is a stand-in for the spacecraft's power generators (called RTGs). Above that, a silvery canister holds the spacecraft's magnetometer in its stowed configuration. https://photojournal.jpl.nasa.gov/catalog/PIA21477

  5. Summary of AH-1G flight vibration data for validation of coupled rotor-fuselage analyses

    NASA Technical Reports Server (NTRS)

    Dompka, R. V.; Cronkhite, J. D.

    1986-01-01

    Under a NASA research program designated DAMVIBS (Design Analysis Methods for VIBrationS), four U. S. helicopter industry participants (Bell Helicopter, Boeing Vertol, McDonnell Douglas Helicopter, and Sikorsky Aircraft) are to apply existing analytical methods for calculating coupled rotor-fuselage vibrations of the AH-1G helicopter for correlation with flight test data from an AH-1G Operational Load Survey (OLS) test program. Bell Helicopter, as the manufacturer of the AH-1G, was asked to provide pertinent rotor data and to collect the OLS flight vibration data needed to perform the correlations. The analytical representation of the fuselage structure is based on a NASTRAN finite element model (FEM) developed by Bell which has been extensively documented and correlated with ground vibration tests.The AH-1G FEM was provided to each of the participants for use in their coupled rotor-fuselage analyses. This report describes the AH-1G OLS flight test program and provides the flight conditions and measured vibration data to be used by each participant in their correlation effort. In addition, the mechanical, structural, inertial and aerodynamic data for the AH-1G two-bladed teetering main rotor system are presented. Furthermore, modifications to the NASTRAN FEM of the fuselage structure that are necessary to make it compatible with the OLS test article are described. The AH-1G OLS flight test data was found to be well documented and provide a sound basis for evaluating currently existing analysis methods used for calculation of coupled rotor-fuselage vibrations.

  6. Voyager Test Model Configuration

    NASA Image and Video Library

    2017-07-05

    This archival photo shows the Voyager proof test model, which did not fly in space, in the 25-foot space simulator chamber at NASA's Jet Propulsion Laboratory, Pasadena, California, on December 3, 1976. The spacecraft is seen here with its scan platform, which holds several of its science instruments, in the deployed position. https://photojournal.jpl.nasa.gov/catalog/PIA21734

  7. Embryonic Exposure to the Environmental Neurotoxin BMAA Negatively Impacts Early Neuronal Development and Progression of Neurodegeneration in the Sod1-G93R Zebrafish Model of Amyotrophic Lateral Sclerosis.

    PubMed

    Powers, Samantha; Kwok, Samantha; Lovejoy, Emily; Lavin, Tom; Sher, Roger

    2017-01-25

    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder leading to progressive paralysis and death within 2-5 years after diagnosis. Sporadic cases (SALS) comprise ∼90% of cases with the remaining 10% familial (FALS) caused by mutations in ∼27 genes. The vast heterogeneity seen in age and location of disease onset, rate of progression, and duration of disease have been linked with genetic and environmental influences in both SALS and FALS cases. Increased ALS incidence clusters in Guam, southern France, and Maryland have been linked with exposure to Beta-methylamino-L-alanine (BMAA), a non-proteinogenic amino acid produced by cyanobacteria, dinoflaggelates, and diatoms. We embryonically exposed zebrafish, Danio rerio, (transgenically overexpressing a FALS-causing SOD1-G93R mutation) to BMAA to investigate early motor neuron outgrowth in larvae and endurance and fatigability in 5-month adults. SOD1-G93R zebrafish showed decreased embryonic nerve length with increased BMAA dose, a phenotypic change mirrored in 5-month performance measures of weaker swimming and increased fatigability. In contrast, transgenic fish overexpressing wild-type SOD1 were resistant to phenotypic changes, indicating a potential neuroprotective function of healthy SOD1. We show that the etiology of genetic ALS animal models can be influenced by environmental exposures, and that embryonic toxin exposures can result in changes to both early and adult measures. We demonstrate that zebrafish can be a robust model for investigating causes of ALS heterogeneity. Establishing these links between developmental and adult ALS-like symptoms in the zebrafish increases the power of this model for toxicological and drug screens.

  8. Solubility of chlorargyrite (AgCl(cr./l.)) in water: New experimental data and a predictive model valid for a wide range of temperatures (273-873 K) and water densities (0.01-1 g·cm-3)

    NASA Astrophysics Data System (ADS)

    Akinfiev, Nikolay N.; Zotov, Alexander V.

    2016-04-01

    The solubility of chlorargyrite, AgCl(cr./l.), in pure water at 623, 673 and 753 (±2) K as a function of pressure in a wide range aqueous densities (0.01-0.7 g·cm-3) was determined using various experimental approaches. Combined theoretical quantum chemistry simulations of Ag speciation and structure with a recently developed equation of state (EoS) for aqueous neutral species (Akinfiev and Diamond, 2003) were applied to describe published and newly made AgCl(cr./l.) solubility measurements in water. The use of the employed EoS for AgCl(H2O)(aq) cluster is found out to provide a good description of the whole set of experimental measurements in a wide range of temperatures (273-753 K), water densities (0.01-0.7 g·cm-3), and pressures of 0.1-100 MPa. Also, the proposed AgCl(H2O)(aq) thermodynamic description is proved to be valid for a dense aqueous fluid (0.7-1 g·cm-3) at 273-623 K and saturation water pressure. Although silver obviously shows greater affinity to dense aqueous fluid, AgCl hydration in the vapour phase is demonstrated to be also significant. A model extrapolation to magmatic conditions predicts an appreciable silver content even in low density fluids, thus supporting the hypothesis of metal transport with vapour.

  9. Test Administration Models

    ERIC Educational Resources Information Center

    Becker, Kirk A.; Bergstrom, Betty A.

    2013-01-01

    The need for increased exam security, improved test formats, more flexible scheduling, better measurement, and more efficient administrative processes has caused testing agencies to consider converting the administration of their exams from paper-and-pencil to computer-based testing (CBT). Many decisions must be made in order to provide an optimal…

  10. Test Administration Models

    ERIC Educational Resources Information Center

    Becker, Kirk A.; Bergstrom, Betty A.

    2013-01-01

    The need for increased exam security, improved test formats, more flexible scheduling, better measurement, and more efficient administrative processes has caused testing agencies to consider converting the administration of their exams from paper-and-pencil to computer-based testing (CBT). Many decisions must be made in order to provide an optimal…

  11. Testing and validating environmental models

    USGS Publications Warehouse

    Kirchner, J.W.; Hooper, R.P.; Kendall, C.; Neal, C.; Leavesley, G.

    1996-01-01

    Generally accepted standards for testing and validating ecosystem models would benefit both modellers and model users. Universally applicable test procedures are difficult to prescribe, given the diversity of modelling approaches and the many uses for models. However, the generally accepted scientific principles of documentation and disclosure provide a useful framework for devising general standards for model evaluation. Adequately documenting model tests requires explicit performance criteria, and explicit benchmarks against which model performance is compared. A model's validity, reliability, and accuracy can be most meaningfully judged by explicit comparison against the available alternatives. In contrast, current practice is often characterized by vague, subjective claims that model predictions show 'acceptable' agreement with data; such claims provide little basis for choosing among alternative models. Strict model tests (those that invalid models are unlikely to pass) are the only ones capable of convincing rational skeptics that a model is probably valid. However, 'false positive' rates as low as 10% can substantially erode the power of validation tests, making them insufficiently strict to convince rational skeptics. Validation tests are often undermined by excessive parameter calibration and overuse of ad hoc model features. Tests are often also divorced from the conditions under which a model will be used, particularly when it is designed to forecast beyond the range of historical experience. In such situations, data from laboratory and field manipulation experiments can provide particularly effective tests, because one can create experimental conditions quite different from historical data, and because experimental data can provide a more precisely defined 'target' for the model to hit. We present a simple demonstration showing that the two most common methods for comparing model predictions to environmental time series (plotting model time series

  12. Equivalent Linear Logistic Test Models.

    ERIC Educational Resources Information Center

    Bechger, Timo M.; Verstralen, Huub H. F. M.; Verhelst, Norma D.

    2002-01-01

    Discusses the Linear Logistic Test Model (LLTM) and demonstrates that there are many equivalent ways to specify a model. Analyzed a real data set (300 responses to 5 analogies) using a Lagrange multiplier test for the specification of the model, and demonstrated that there may be many ways to change the specification of an LLTM and achieve the…

  13. Testing Mantle Circulation Models

    NASA Astrophysics Data System (ADS)

    Webb, P.; Davies, D.; Davies, J.

    2008-12-01

    Over the past decade, a new family of mantle convection models have been developed, which are conditioned by recent plate motion history (e.g. Bunge et al., 1997). They are commonly known as 'mantle circulation models' and allow for comparisons between present-day model predictions and ever improving seismic tomography images (e.g. Li et al. 2008). In this work, we present results from systematic investigations into the influence of various model parameters upon final model prediction/tomography correlations, to obtain a better understanding of their relative importance. These include a range of material properties, such as the radial viscosity structure, the Clapeyron slope of mineral phase transitions and compressibility; in addition to other aspects, such as the initial condition for the simulation. For our comparisons, we focus in particular on two large robust mid-mantle seismic anomalies, which others have related to the subduction of the Farallon and Tethys plates (e.g. Romanowicz, 1980). While these features are recovered with some fidelity in most simulations, the match can vary greatly. We find that there is a great deal of information in this mismatch, which includes information on the plate motion history.

  14. Ship Model Testing

    DTIC Science & Technology

    2016-06-07

    ELEMENT NUMBER 6. AUTHOR(S) Richard A. Royce 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND...grant identifies numerous facilities improvements for Webb Institute. Since the final approval of the grant in July of 2010, Webb has completed work ...Walling, R. J. 2012 "Planing craft ride control using a neural network," Webb Institute, Glen Cove, NY). This project resulted in a working test platform

  15. Diagnostic tests for model structure

    NASA Astrophysics Data System (ADS)

    McMillan, Hilary; Clark, Martyn; Woods, Ross; Bowden, Breck

    2010-05-01

    It is common knowledge that hydrological models based on inappropriate conceptualisations of the catchment can still be calibrated to give good performance in reproducing discharge records. Calibrated models of this type are unsuitable for many of their intended uses. To improve model conceptualisations and allow models to be tailored for individual applications and catchments, modellers need a toolbox of diagnostic tests for model structure. These tests would use a range of field measurements to allow hydrological modellers to test hypotheses about different aspects of model structure. This presentation demonstrates how multiple datasets (rain, flow, soil moisture, tracer studies) can be used to develop perceptual and conceptual models; using a case study in the intensively monitored Mahurangi catchment in New Zealand. Our emphasis is on the use of field data to target individual modelling decisions, and hence to draw conclusions relevant to model building at the catchment scale. The goal is to "bridge the gap" between experimental studies and larger-scale model simulations. The model building decisions are then tested using the FUSE multi-model framework. The framework allows independent control of model choices in representing a range of storages and fluxes. We compare structural diagnostics from field data, realistic and unrealistic model structures, with the aim of untangling the effects of model structure and parameterisation.

  16. Testing the model for testing competency.

    PubMed

    Keating, Sarah B; Rutledge, Dana N; Sargent, Arlene; Walker, Polly

    2003-05-01

    The pilot study to demonstrate the utility of the CBRDM in the practice setting was successful. Using a matrix evaluation tool based on the model's competencies, evaluators were able to observe specific performance behaviors of senior nursing students and new graduates at either the novice or competent levels. The study faced the usual perils of pilot studies, including small sample size, a limited number of items from the total CBRDM, restricted financial resources, inexperienced researchers, unexpected barriers, and untested evaluation tools. It was understood from the beginning of the study that the research would be based on a program evaluation model, analyzing both processes and outcomes. However, the meager data findings led to the desire to continue to study use of the model for practice setting job expectations, career planning for nurses, and curriculum development for educators. Although the California Strategic Planning Committee for Nursing no longer has funding, we hope that others interested in role differentiation issues will take the results of this study and test the model in other practice settings. Its ability to measure higher levels of competency as well as novice and competent should be studied, i.e., proficient, expert, and advanced practice. The CBRDM may be useful in evaluating student and nurse performance, defining role expectations, and identifying the preparation necessary for the roles. The initial findings related to the two functions as leader and teacher in the care provider and care coordinator roles led to much discussion about helping students and nurses develop competence. Additional discussion focused on the roles as they apply to settings such as critical care or primary health care. The model is useful for all of nursing as it continues to define its levels of practice and their relationship to on-the-job performance, curriculum development, and career planning.

  17. Frequentist tests for Bayesian models

    NASA Astrophysics Data System (ADS)

    Lucy, L. B.

    2016-04-01

    Analogues of the frequentist chi-square and F tests are proposed for testing goodness-of-fit and consistency for Bayesian models. Simple examples exhibit these tests' detection of inconsistency between consecutive experiments with identical parameters, when the first experiment provides the prior for the second. In a related analysis, a quantitative measure is derived for judging the degree of tension between two different experiments with partially overlapping parameter vectors.

  18. Model test plan for HV pulse testing

    NASA Astrophysics Data System (ADS)

    Dunbar, W. G.; Schweickart, D. L.

    This pulse test plan will contain the configuration, operation and maintenance test requirements, equipment requirements, and procedures for high-voltage pulse testing of aerospace high power experimental and operational parts and equipment. The plan details peak voltage and test pulse rise time and fall time as they are applied to evaluate electrical insulation within electrical and electronic system components.

  19. Avian models for toxicity testing

    USGS Publications Warehouse

    Hill, E.F.; Hoffman, D.J.

    1984-01-01

    The use of birds as test models in experimental and environmental toxicology as related to health effects is reviewed, and an overview of descriptive tests routinely used in wildlife toxicology is provided. Toxicologic research on birds may be applicable to human health both directly by their use as models for mechanistic and descriptive studies and indirectly as monitors of environmental quality. Topics include the use of birds as models for study of teratogenesis and embryotoxicity, neurotoxicity, behavior, trends of environmental pollution, and for use in predictive wildlife toxicology. Uses of domestic and wild-captured birds are discussed.

  20. Investigation of difficult component effects on FEM vibration prediction for the AH-1G helicopter

    NASA Technical Reports Server (NTRS)

    Dompka, Robert V.

    1988-01-01

    Under the NASA-sponsored Design Analysis Methods for Vibrations program, a series of ground vibration tests and NASTRAN finite element model correlations were conducted on the Bell AH-1G helicopter gunship to investigate the effects of difficult components on the vibration response of the airframe. Secondary structure and damping were found to have significant effects on the frequency response of the airframe above 15 Hz. The nonlinear effects of thrust stiffening and elastomeric mounts on the low-frequency pylon modes below the main rotor were also significant.

  1. Time-course and characterization of orolingual motor deficits in SOD1-G93A mice

    PubMed Central

    Smittkamp, Susan E.; Brown, Jordan W.; Stanford, John A.

    2008-01-01

    Amyotrophic lateral sclerosis (ALS) is a progressive degenerative disease affecting upper and lower motor neurons. Symptom onset may occur in the muscles of the limbs (spinal onset) or those of the head and neck (bulbar onset). Bulbar involvement is particularly important in ALS as it is associated with increased morbidity and mortality. The purpose of this study was to characterize bulbar motor deficits in the SOD1-G93A mouse model of familial ALS. We measured orolingual motor function by placing thirsty mice in a customized operant chamber that allows for measurement of tongue force and lick rhythm as animals lick water from an isometric disc. Testing spanned the pre-symptomatic, symptomatic, and end-stage segments of the disease. Rotarod performance, fore- and hindlimb grip strength, and locomotor activity were also monitored regularly during this period. We found that spinal involvement was apparent first, with both fore- and hindlimb grip strength being affected in SOD1-G93A mice from the onset of testing (64 days of age). Rotarod performance was affected by 71 days of age. Locomotor activity was not affected, even near end-stage. Bulbar involvement appeared much later, with tongue motility being affected by 100 days of age. Tongue force was affected by 115 days of age. To our knowledge, these findings are the first to describe the onset of bulbar v. spinal motor signs and characterize orolingual motor deficits in this preclinical model of ALS. PMID:18061359

  2. Viking Mars lander 1975 dynamic test model/orbiter developmental test model forced vibration test

    NASA Technical Reports Server (NTRS)

    Fortenberry, J.; Brownlee, G. R.

    1974-01-01

    The Viking Mars Lander 1975 dynamic test model and orbiter developmental test model were subjected to forced vibration sine tests. Flight acceptance (FA) and type approval (TA) test levels were applied to the spacecraft structure in a longitudinal test configuration using a 133,440-N (30,000-lb) force shaker. Testing in the two lateral axes (X, Y) was performed at lower levels using four 667-N (150-lb) force shakers. Forced vibration qualification (TA) test levels were successfully imposed on the spacecraft at frequencies down to 10 Hz. Measured responses showed the same character as analytical predictions, and correlation was reasonably good. Because of control system test tolerances, orbiter primary structure generally did not reach the design load limits attained in earlier static testing. A post-test examination of critical orbiter structure disclosed no apparent damage to the structure as a result of the test environment.

  3. Remote control missile model test

    NASA Technical Reports Server (NTRS)

    Allen, Jerry M.; Shaw, David S.; Sawyer, Wallace C.

    1989-01-01

    An extremely large, systematic, axisymmetric body/tail fin data base was gathered through tests of an innovative missile model design which is described herein. These data were originally obtained for incorporation into a missile aerodynamics code based on engineering methods (Program MISSILE3), but can also be used as diagnostic test cases for developing computational methods because of the individual-fin data included in the data base. Detailed analysis of four sample cases from these data are presented to illustrate interesting individual-fin force and moment trends. These samples quantitatively show how bow shock, fin orientation, fin deflection, and body vortices can produce strong, unusual, and computationally challenging effects on individual fin loads. Comparisons between these data and calculations from the SWINT Euler code are also presented.

  4. The H,G_1,G_2 photometric system with scarce observational data

    NASA Astrophysics Data System (ADS)

    Penttilä, A.; Granvik, M.; Muinonen, K.; Wilkman, O.

    2014-07-01

    photometric fits to very scarce and low-accuracy data. There are a few details that should be considered with the H,G_1,G_2 or H,G_{12} systems with scarce data. The first point is the distribution of errors in the fit. The original H,G system allowed linear regression in the flux space, thus making the estimation computationally easier. The same principle was repeated with the H,G_1,G_2 system. There is, however, a major hidden assumption in the transformation. With regression modeling, the residuals should be distributed symmetrically around zero. If they are normally distributed, even better. We have noticed that, at least with some NEO observations, the residuals in the flux space are far from symmetric, and seem to be much more symmetric in the magnitude space. The result is that the nonlinear fit in magnitude space is far more reliable than the linear fit in the flux space. Since the computers and nonlinear regression algorithms are efficient enough, we conclude that, in many cases, with low-accuracy data the nonlinear fit should be favored. In fact, there are statistical procedures that should be employed with the photometric fit. At the moment, the choice between the three-parameter and two-parameter versions is simply based on subjective decision-making. By checking parameter error and model comparison statistics, the choice could be done objectively. Similarly, the choice between the linear fit in flux space and the nonlinear fit in magnitude space should be based on a statistical test of unbiased residuals. Furthermore, the so-called Box-Cox transform could be employed to find an optimal transformation somewhere between the magnitude and flux spaces. The H,G_1,G_2 system is based on cubic splines, and is therefore a bit more complicated to implement than a system with simpler basis functions. The same applies to a complete program that would automatically choose the best transforms to data, test if two- or three-parameter version of the model should be fitted, and

  5. Scale Model Acoustic Test Overview

    NASA Technical Reports Server (NTRS)

    Counter, Douglas D.; Houston, Janice D.

    2012-01-01

    Launch environments, such as liftoff acoustic (LOA) and ignition overpressure (IOP), are important design factors for any vehicle and are dependent upon the design of both the vehicle and the ground systems. LOA environments are used directly in the development of vehicle vibro-acoustic environments and IOP is used in the loads assessment. The Scale Model Acoustic Test (SMAT) program was implemented to verify the Space Launch Systems LOA and IOP environments for the vehicle and ground systems including the Mobile Launcher (ML) and tower. The SMAT is currently in the design and fabrication phase. The SMAT program is described in this presentation.

  6. Genetic biomarkers for ALS disease in transgenic SOD1(G93A) mice.

    PubMed

    Calvo, Ana C; Manzano, Raquel; Atencia-Cibreiro, Gabriela; Oliván, Sara; Muñoz, María J; Zaragoza, Pilar; Cordero-Vázquez, Pilar; Esteban-Pérez, Jesús; García-Redondo, Alberto; Osta, Rosario

    2012-01-01

    The pathophysiological mechanisms of both familial and sporadic Amyotrophic Lateral Sclerosis (ALS) are unknown, although growing evidence suggests that skeletal muscle tissue is a primary target of ALS toxicity. Skeletal muscle biopsies were performed on transgenic SOD1(G93A) mice, a mouse model of ALS, to determine genetic biomarkers of disease longevity. Mice were anesthetized with isoflurane, and three biopsy samples were obtained per animal at the three main stages of the disease. Transcriptional expression levels of seventeen genes, Ankrd1, Calm1, Col19a1, Fbxo32, Gsr, Impa1, Mef2c, Mt2, Myf5, Myod1, Myog, Nnt, Nogo A, Pax7, Rrad, Sln and Snx10, were tested in each muscle biopsy sample. Total RNA was extracted using TRIzol Reagent according to the manufacturer's protocol, and variations in gene expression were assayed by real-time PCR for all of the samples. The Pearson correlation coefficient was used to determine the linear correlation between transcriptional expression levels throughout disease progression and longevity. Consistent with the results obtained from total skeletal muscle of transgenic SOD1(G93A) mice and 74-day-old denervated mice, five genes (Mef2c, Gsr, Col19a1, Calm1 and Snx10) could be considered potential genetic biomarkers of longevity in transgenic SOD1(G93A) mice. These results are important because they may lead to the exploration of previously unexamined tissues in the search for new disease biomarkers and even to the application of these findings in human studies.

  7. Genetic Biomarkers for ALS Disease in Transgenic SOD1G93A Mice

    PubMed Central

    Calvo, Ana C.; Manzano, Raquel; Atencia-Cibreiro, Gabriela; Oliván, Sara; Muñoz, María J.; Zaragoza, Pilar; Cordero-Vázquez, Pilar; Esteban-Pérez, Jesús; García-Redondo, Alberto; Osta, Rosario

    2012-01-01

    The pathophysiological mechanisms of both familial and sporadic Amyotrophic Lateral Sclerosis (ALS) are unknown, although growing evidence suggests that skeletal muscle tissue is a primary target of ALS toxicity. Skeletal muscle biopsies were performed on transgenic SOD1G93A mice, a mouse model of ALS, to determine genetic biomarkers of disease longevity. Mice were anesthetized with isoflurane, and three biopsy samples were obtained per animal at the three main stages of the disease. Transcriptional expression levels of seventeen genes, Ankrd1, Calm1, Col19a1, Fbxo32, Gsr, Impa1, Mef2c, Mt2, Myf5, Myod1, Myog, Nnt, Nogo A, Pax7, Rrad, Sln and Snx10, were tested in each muscle biopsy sample. Total RNA was extracted using TRIzol Reagent according to the manufacturer's protocol, and variations in gene expression were assayed by real-time PCR for all of the samples. The Pearson correlation coefficient was used to determine the linear correlation between transcriptional expression levels throughout disease progression and longevity. Consistent with the results obtained from total skeletal muscle of transgenic SOD1G93A mice and 74-day-old denervated mice, five genes (Mef2c, Gsr, Col19a1, Calm1 and Snx10) could be considered potential genetic biomarkers of longevity in transgenic SOD1G93A mice. These results are important because they may lead to the exploration of previously unexamined tissues in the search for new disease biomarkers and even to the application of these findings in human studies. PMID:22412900

  8. Characterization of fertilization-blocking monoclonal antibody 1G12 with human sperm-immobilizing activity

    PubMed Central

    KOMORI, S; KAMEDA, K; SAKATA, K; HASEGAWA, A; TOJI, H; TSUJI, Y; SHIBAHARA, H; KOYAMA, K; ISOJIMA, S

    1997-01-01

    A mouse hybridoma (1G12) producing sperm-immobilizing MoAb to human sperm was established and characterized in order to study the antigens relevant to sperm immobilization by antibodies. MoAb 1G12 had strong sperm-immobilizing and agglutinating activities and also showed a fertilization-blocking activity on in vitro fertilization tests. The antibody absorption experiments showed that MoAb 1G12 reacted not only to ejaculated sperm but also human seminal plasma, suggesting that the corresponding antigen might be a sperm coating antigen. The MoAb also reacted with peripheral blood lymphocytes. In histochemical studies, the epithelia of corpus epididymis were most strongly stained. Ejaculated sperm were stained with a granular pattern for their entire surface by immunofluorescence. MoAb 1G12 recognized polymorphic glycoproteins of 15–25 kD in the ejaculated sperm extract in Western blot analysis. After deglycosilation of the sperm extract, only a single staining band of under 15 kD was detected by MoAb 1G12. This suggests that the antigen epitope recognized by MoAb 1G12 might be a peptide of the core portion of the glycoprotein. MoAb 1G12 might be a useful tool for studying the mechanism of egg–sperm interaction, and also be applied to identifying the corresponding antigen by using gene technology. PMID:9328135

  9. Testing Strategies for Model-Based Development

    NASA Technical Reports Server (NTRS)

    Heimdahl, Mats P. E.; Whalen, Mike; Rajan, Ajitha; Miller, Steven P.

    2006-01-01

    This report presents an approach for testing artifacts generated in a model-based development process. This approach divides the traditional testing process into two parts: requirements-based testing (validation testing) which determines whether the model implements the high-level requirements and model-based testing (conformance testing) which determines whether the code generated from a model is behaviorally equivalent to the model. The goals of the two processes differ significantly and this report explores suitable testing metrics and automation strategies for each. To support requirements-based testing, we define novel objective requirements coverage metrics similar to existing specification and code coverage metrics. For model-based testing, we briefly describe automation strategies and examine the fault-finding capability of different structural coverage metrics using tests automatically generated from the model.

  10. Software Test Models and Implementation of Associated Test Drivers.

    DTIC Science & Technology

    1980-03-01

    for testing - - be it manual, semi-automatic or formal definitions and analytic models, to fully define the range and scope of the test project. In...software test systems. It will be shown that practical driver systems for automatic testing can be implemented from formal definitions of testing types. The... definition involves a discussion on how program branching points and loops affect the number of paths. The process culminates in an algorithm for

  11. Outer planet probe engineering model structural tests

    NASA Technical Reports Server (NTRS)

    Smittkamp, J. A.; Gustin, W. H.; Griffin, M. W.

    1977-01-01

    A series of proof of concept structural tests was performed on an engineering model of the Outer Planets Atmospheric Entry Probe. The tests consisted of pyrotechnic shock, dynamic and static loadings. The tests partially verified the structural concept.

  12. 46 CFR 154.449 - Model test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Model test. 154.449 Section 154.449 Shipping COAST GUARD... § 154.449 Model test. The following analyzed data of a model test of structural elements for independent... factors. (b) Fatigue life. Independent Tank Type C and Process Pressure Vessels...

  13. 46 CFR 154.449 - Model test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Model test. 154.449 Section 154.449 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF... § 154.449 Model test. The following analyzed data of a model test of structural elements for independent...

  14. 46 CFR 154.431 - Model test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Model test. (a) The primary and secondary barrier of a membrane tank, including the corners and joints... 46 Shipping 5 2014-10-01 2014-10-01 false Model test. 154.431 Section 154.431 Shipping COAST GUARD...(c). (b) Analyzed data of a model test for the primary and secondary barrier of the membrane...

  15. 46 CFR 154.431 - Model test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Model test. (a) The primary and secondary barrier of a membrane tank, including the corners and joints... 46 Shipping 5 2011-10-01 2011-10-01 false Model test. 154.431 Section 154.431 Shipping COAST GUARD...(c). (b) Analyzed data of a model test for the primary and secondary barrier of the membrane...

  16. 46 CFR 154.431 - Model test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Model test. (a) The primary and secondary barrier of a membrane tank, including the corners and joints... 46 Shipping 5 2012-10-01 2012-10-01 false Model test. 154.431 Section 154.431 Shipping COAST GUARD...(c). (b) Analyzed data of a model test for the primary and secondary barrier of the membrane...

  17. 46 CFR 154.431 - Model test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Model test. (a) The primary and secondary barrier of a membrane tank, including the corners and joints... 46 Shipping 5 2013-10-01 2013-10-01 false Model test. 154.431 Section 154.431 Shipping COAST GUARD...(c). (b) Analyzed data of a model test for the primary and secondary barrier of the membrane...

  18. 46 CFR 154.431 - Model test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Model test. (a) The primary and secondary barrier of a membrane tank, including the corners and joints... 46 Shipping 5 2010-10-01 2010-10-01 false Model test. 154.431 Section 154.431 Shipping COAST GUARD...(c). (b) Analyzed data of a model test for the primary and secondary barrier of the membrane...

  19. Coupled rotor/fuselage dynamic analysis of the AH-1G helicopter and correlation with flight vibrations data

    NASA Technical Reports Server (NTRS)

    Corrigan, J. C.; Cronkhite, J. D.; Dompka, R. V.; Perry, K. S.; Rogers, J. P.; Sadler, S. G.

    1989-01-01

    Under a research program designated Design Analysis Methods for VIBrationS (DAMVIBS), existing analytical methods are used for calculating coupled rotor-fuselage vibrations of the AH-1G helicopter for correlation with flight test data from an AH-1G Operational Load Survey (OLS) test program. The analytical representation of the fuselage structure is based on a NASTRAN finite element model (FEM), which has been developed, extensively documented, and correlated with ground vibration test. One procedure that was used for predicting coupled rotor-fuselage vibrations using the advanced Rotorcraft Flight Simulation Program C81 and NASTRAN is summarized. Detailed descriptions of the analytical formulation of rotor dynamics equations, fuselage dynamic equations, coupling between the rotor and fuselage, and solutions to the total system of equations in C81 are included. Analytical predictions of hub shears for main rotor harmonics 2p, 4p, and 6p generated by C81 are used in conjunction with 2p OLS measured control loads and a 2p lateral tail rotor gearbox force, representing downwash impingement on the vertical fin, to excite the NASTRAN model. NASTRAN is then used to correlate with measured OLS flight test vibrations. Blade load comparisons predicted by C81 showed good agreement. In general, the fuselage vibration correlations show good agreement between anslysis and test in vibration response through 15 to 20 Hz.

  20. Testing Galactic Cosmic Ray Models

    NASA Technical Reports Server (NTRS)

    Adams, James H., Jr.

    2009-01-01

    Models of the Galactic Cosmic Ray Environment are used for designing and planning space missions. The existing models will be reviewed. Spectral representations from these models will be compared with measurements of galactic cosmic ray spectra made on balloon flights and satellite flights over a period of more than 50 years.

  1. Testing Galactic Cosmic Ray Models

    NASA Technical Reports Server (NTRS)

    Adams, James H., Jr.

    2010-01-01

    Models of the Galactic Cosmic Ray Environment are used for designing and planning space missions. The exising models will be reviewed. Spectral representations from these models will be compared with measurements of galactic cosmic ray spectra made on balloon flights and satellite flights over a period of more than 50 years.

  2. Testing of constitutive models in LAME.

    SciTech Connect

    Hammerand, Daniel Carl; Scherzinger, William Mark

    2007-09-01

    Constitutive models for computational solid mechanics codes are in LAME--the Library of Advanced Materials for Engineering. These models describe complex material behavior and are used in our finite deformation solid mechanics codes. To ensure the correct implementation of these models, regression tests have been created for constitutive models in LAME. A selection of these tests is documented here. Constitutive models are an important part of any solid mechanics code. If an analysis code is meant to provide accurate results, the constitutive models that describe the material behavior need to be implemented correctly. Ensuring the correct implementation of constitutive models is the goal of a testing procedure that is used with the Library of Advanced Materials for Engineering (LAME) (see [1] and [2]). A test suite for constitutive models can serve three purposes. First, the test problems provide the constitutive model developer a means to test the model implementation. This is an activity that is always done by any responsible constitutive model developer. Retaining the test problem in a repository where the problem can be run periodically is an excellent means of ensuring that the model continues to behave correctly. A second purpose of a test suite for constitutive models is that it gives application code developers confidence that the constitutive models work correctly. This is extremely important since any analyst that uses an application code for an engineering analysis will associate a constitutive model in LAME with the application code, not LAME. Therefore, ensuring the correct implementation of constitutive models is essential for application code teams. A third purpose of a constitutive model test suite is that it provides analysts with example problems that they can look at to understand the behavior of a specific model. Since the choice of a constitutive model, and the properties that are used in that model, have an enormous effect on the results of an

  3. GEOCHEMICAL TESTING AND MODEL DEVELOPMENT - RESIDUAL TANK WASTE TEST PLAN

    SciTech Connect

    CANTRELL KJ; CONNELLY MP

    2010-03-09

    This Test Plan describes the testing and chemical analyses release rate studies on tank residual samples collected following the retrieval of waste from the tank. This work will provide the data required to develop a contaminant release model for the tank residuals from both sludge and salt cake single-shell tanks. The data are intended for use in the long-term performance assessment and conceptual model development.

  4. Astronaut adaptation to 1 G following long duration space flight

    NASA Technical Reports Server (NTRS)

    Walker, John; Greenisen, Michael; Cowell, Lynda L.; Squires, William G.

    1991-01-01

    The paper reviews the results of studies of changes undergone by several physiological systems (including the cardiovascular system, the fluid and electrolyte characteristics, the red blood cells, the bone and the muscle tissues, and the exercise capacity) due to the exposures to microgravity and to the adaptation to 1 G after a long-duration space flight. Special attention is given to the effects of various training protocols and countermeasures used to attenuate the physiological problems encountered upon return from space.

  5. Astronaut adaptation to 1 G following long duration space flight

    NASA Technical Reports Server (NTRS)

    Walker, John; Greenisen, Michael; Cowell, Lynda L.; Squires, William G.

    1991-01-01

    The paper reviews the results of studies of changes undergone by several physiological systems (including the cardiovascular system, the fluid and electrolyte characteristics, the red blood cells, the bone and the muscle tissues, and the exercise capacity) due to the exposures to microgravity and to the adaptation to 1 G after a long-duration space flight. Special attention is given to the effects of various training protocols and countermeasures used to attenuate the physiological problems encountered upon return from space.

  6. Preliminary characterisation of new glass reference materials (GSA-1G, GSC-1G, GSD-1G and GSE-1G) by laser ablation-inductively coupled plasma-mass spectrometry using 193 nm, 213 nm and 266 nm wavelengths

    USGS Publications Warehouse

    Guillong, M.; Hametner, K.; Reusser, E.; Wilson, S.A.; Gunther, D.

    2005-01-01

    New glass reference materials GSA-1G, GSC-1G, GSD-1G and GSE-1G have been characterised using a prototype solid state laser ablation system capable of producing wavelengths of 193 nm, 213 nm and 266 nm. This system allowed comparison of the effects of different laser wavelengths under nearly identical ablation and ICP operating conditions. The wavelengths 213 nm and 266 nm were also used at higher energy densities to evaluate the influence of energy density on quantitative analysis. In addition, the glass reference materials were analysed using commercially available 266 nm Nd:YAG and 193 nm ArF excimer lasers. Laser ablation analysis was carried out using both single spot and scanning mode ablation. Using laser ablation ICP-MS, concentrations of fifty-eight elements were determined with external calibration to the NIST SRM 610 glass reference material. Instead of applying the more common internal standardisation procedure, the total concentration of all element oxide concentrations was normalised to 100%. Major element concentrations were compared with those determined by electron microprobe. In addition to NIST SRM 610 for external calibration, USGS BCR-2G was used as a more closely matrix-matched reference material in order to compare the effect of matrix-matched and non matrix-matched calibration on quantitative analysis. The results show that the various laser wavelengths and energy densities applied produced similar results, with the exception of scanning mode ablation at 266 nm without matrix-matched calibration where deviations up to 60% from the average were found. However, results acquired using a scanning mode with a matrix-matched calibration agreed with results obtained by spot analysis. The increased abundance of large particles produced when using a scanning ablation mode with NIST SRM 610, is responsible for elemental fractionation effects caused by incomplete vaporisation of large particles in the ICP.

  7. A Model for Optimal Constrained Adaptive Testing.

    ERIC Educational Resources Information Center

    van der Linden, Wim J.; Reese, Lynda M.

    1998-01-01

    Proposes a model for constrained computerized adaptive testing in which the information in the test at the trait level (theta) estimate is maximized subject to the number of possible constraints on the content of the test. Test assembly relies on a linear-programming approach. Illustrates the approach through simulation with items from the Law…

  8. Identification of the isomer of methionine sulfoximine that extends the lifespan of the SOD1 G93A mouse.

    PubMed

    Brusilow, William S A

    2017-04-24

    In previous studies methionine sulfoximine (MSO) significantly extended the lifespan of the SOD1 G93A mouse model for ALS. Those studies used commercially available MSO, which is a racemic mixture of the LS and LR diastereomers, leaving unanswered the question of which isomer was responsible for the therapeutic effects. In this study we tested both purified isomers and showed that the LS isomer, a well-characterized inhibitor of glutamine synthetase, extends the lifespan of these mice, but the LR isomer, which has no known activity, does not.

  9. Testing the Testing: Validity of a State Growth Model

    ERIC Educational Resources Information Center

    Brown, Kim Trask

    2008-01-01

    Possible threats to the validity of North Carolina's accountability model used to predict academic growth were investigated in two ways: the state's regression equations were replicated but updated to utilize current testing data and not that from years past as in the state's current model; and the updated equations were expanded to include…

  10. APOL1-G0 or APOL1-G2 Transgenic Models Develop Preeclampsia but Not Kidney Disease.

    PubMed

    Bruggeman, Leslie A; Wu, Zhenzhen; Luo, Liping; Madhavan, Sethu M; Konieczkowski, Martha; Drawz, Paul E; Thomas, David B; Barisoni, Laura; Sedor, John R; O'Toole, John F

    2016-12-01

    APOL1 risk variants are associated with kidney disease in blacks, but the mechanisms of renal injury associated with APOL1 risk variants are unknown. Because APOL1 is unique to humans and some primates, we created transgenic (Tg) mice using the promoter of nephrin-encoding Nphs1 to express the APOL1 reference sequence (G0) or the G2 risk variant in podocytes, establishing Tg lines with a spectrum of APOL1 expression levels. Podocytes from Tg-G0 and Tg-G2 mice did not undergo necrosis, apoptosis, or autophagic cell death in vivo, even in lines with highly expressed transgenes. Further, Tg-G0 and Tg-G2 mice did not develop kidney pathology, proteinuria, or azotemia as of 300 days of age. However, by 200 days of age, Tg-G2 mice had significantly lower podocyte density than age-matched WT and Tg-G0 mice had, a difference that was not evident at weaning. Notably, a pregnancy-associated phenotype that encompassed eclampsia, preeclampsia, fetal/neonatal deaths, and small litter sizes occurred in some Tg-G0 mice and more severely in Tg-G2 mice. Similar to human placenta, placentas of Tg mice expressed APOL1. Overall, these results suggest podocyte depletion could predispose individuals with APOL1 risk genotypes to kidney disease in response to a second stressor, and add to other published evidence associating APOL1 expression with preeclampsia. Copyright © 2016 by the American Society of Nephrology.

  11. Used Fuel Testing Transportation Model

    SciTech Connect

    Ross, Steven B.; Best, Ralph E.; Maheras, Steven J.; Jensen, Philip J.; England, Jeffery L.; LeDuc, Dan

    2014-09-25

    This report identifies shipping packages/casks that might be used by the Used Nuclear Fuel Disposition Campaign Program (UFDC) to ship fuel rods and pieces of fuel rods taken from high-burnup used nuclear fuel (UNF) assemblies to and between research facilities for purposes of evaluation and testing. Also identified are the actions that would need to be taken, if any, to obtain U.S. Nuclear Regulatory (NRC) or other regulatory authority approval to use each of the packages and/or shipping casks for this purpose.

  12. Linear Logistic Test Modeling with R

    ERIC Educational Resources Information Center

    Baghaei, Purya; Kubinger, Klaus D.

    2015-01-01

    The present paper gives a general introduction to the linear logistic test model (Fischer, 1973), an extension of the Rasch model with linear constraints on item parameters, along with eRm (an R package to estimate different types of Rasch models; Mair, Hatzinger, & Mair, 2014) functions to estimate the model and interpret its parameters. The…

  13. Linear Logistic Test Modeling with R

    ERIC Educational Resources Information Center

    Baghaei, Purya; Kubinger, Klaus D.

    2015-01-01

    The present paper gives a general introduction to the linear logistic test model (Fischer, 1973), an extension of the Rasch model with linear constraints on item parameters, along with eRm (an R package to estimate different types of Rasch models; Mair, Hatzinger, & Mair, 2014) functions to estimate the model and interpret its parameters. The…

  14. 46 CFR 154.449 - Model test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Model test. 154.449 Section 154.449 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Independent Tank Type B § 154.449 Model test. The following...

  15. Biglan Model Test Based on Institutional Diversity.

    ERIC Educational Resources Information Center

    Roskens, Ronald W.; Creswell, John W.

    The Biglan model, a theoretical framework for empirically examining the differences among subject areas, classifies according to three dimensions: adherence to common set of paradigms (hard or soft), application orientation (pure or applied), and emphasis on living systems (life or nonlife). Tests of the model are reviewed, and a further test is…

  16. Test of the antiorthostatic suspension model on mice - Effects on the inflammatory cell response

    NASA Technical Reports Server (NTRS)

    Rosenkrans, Charles F., Jr.; Chapes, Stephen K.; Fleming, Sherry D.

    1990-01-01

    The antiorthostatic suspension model was tested for use as a 1G model to study the effects of factors that will be encountered during space travel on inflammation. No differences were found in inflammatory cells induced in antiorthostatically suspended mice. However, the superoxide response (used for oxidative killing of bacteria such as S. aureus) was impaired in antiorthostatically oriented mice compared to control mice. Elevated corticosterone levels were found in antiorthostatically suspended mice, indicating that stress may be a factor in the model. If the stress factor of the model correlates with the physiological stress of space flight, antiorthostatic suspension may be an acceptable model for studying inflammatory responses in mice.

  17. Test of the antiorthostatic suspension model on mice - Effects on the inflammatory cell response

    NASA Technical Reports Server (NTRS)

    Rosenkrans, Charles F., Jr.; Chapes, Stephen K.; Fleming, Sherry D.

    1990-01-01

    The antiorthostatic suspension model was tested for use as a 1G model to study the effects of factors that will be encountered during space travel on inflammation. No differences were found in inflammatory cells induced in antiorthostatically suspended mice. However, the superoxide response (used for oxidative killing of bacteria such as S. aureus) was impaired in antiorthostatically oriented mice compared to control mice. Elevated corticosterone levels were found in antiorthostatically suspended mice, indicating that stress may be a factor in the model. If the stress factor of the model correlates with the physiological stress of space flight, antiorthostatic suspension may be an acceptable model for studying inflammatory responses in mice.

  18. Building Test Cases through Model Driven Engineering

    NASA Astrophysics Data System (ADS)

    Sousa, Helaine; Lopes, Denivaldo; Abdelouahab, Zair; Hammoudi, Slimane; Claro, Daniela Barreiro

    Recently, Model Driven Engineering (MDE) has been proposed to face the complexity in the development, maintenance and evolution of large and distributed software systems. Model Driven Architecture (MDA) is an example of MDE. In this context, model transformations enable a large reuse of software systems through the transformation of a Platform Independent Model into a Platform Specific Model. Although source code can be generated from models, defects can be injected during the modeling or transformation process. In order to delivery software systems without defects that cause errors and fails, the source code must be submitted to test. In this paper, we present an approach that takes care of test in the whole software life cycle, i.e. it starts in the modeling level and finishes in the test of source code of software systems. We provide an example to illustrate our approach.

  19. A model for field toxicity tests

    USGS Publications Warehouse

    Kaiser, Mark S.; Finger, Susan E.

    1996-01-01

    Toxicity tests conducted under field conditions present an interesting challenge for statistical modelling. In contrast to laboratory tests, the concentrations of potential toxicants are not held constant over the test. In addition, the number and identity of toxicants that belong in a model as explanatory factors are not known and must be determined through a model selection process. We present one model to deal with these needs. This model takes the record of mortalities to form a multinomial distribution in which parameters are modelled as products of conditional daily survival probabilities. These conditional probabilities are in turn modelled as logistic functions of the explanatory factors. The model incorporates lagged values of the explanatory factors to deal with changes in the pattern of mortalities over time. The issue of model selection and assessment is approached through the use of generalized information criteria and power divergence goodness-of-fit tests. These model selection criteria are applied in a cross-validation scheme designed to assess the ability of a model to both fit data used in estimation and predict data deleted from the estimation data set. The example presented demonstrates the need for inclusion of lagged values of the explanatory factors and suggests that penalized likelihood criteria may not provide adequate protection against overparameterized models in model selection.

  20. The Vanishing Tetrad Test: Another Test of Model Misspecification

    ERIC Educational Resources Information Center

    Roos, J. Micah

    2014-01-01

    The Vanishing Tetrad Test (VTT) (Bollen, Lennox, & Dahly, 2009; Bollen & Ting, 2000; Hipp, Bauer, & Bollen, 2005) is an extension of the Confirmatory Tetrad Analysis (CTA) proposed by Bollen and Ting (Bollen & Ting, 1993). VTT is a powerful tool for detecting model misspecification and can be particularly useful in cases in which…

  1. The Vanishing Tetrad Test: Another Test of Model Misspecification

    ERIC Educational Resources Information Center

    Roos, J. Micah

    2014-01-01

    The Vanishing Tetrad Test (VTT) (Bollen, Lennox, & Dahly, 2009; Bollen & Ting, 2000; Hipp, Bauer, & Bollen, 2005) is an extension of the Confirmatory Tetrad Analysis (CTA) proposed by Bollen and Ting (Bollen & Ting, 1993). VTT is a powerful tool for detecting model misspecification and can be particularly useful in cases in which…

  2. Vaccine potential of recombinant cathepsinL1G against Fasciola gigantica in mice.

    PubMed

    Changklungmoa, Narin; Phoinok, Natthacha; Yencham, Chonthicha; Sobhon, Prasert; Kueakhai, Pornanan

    2016-08-15

    In this study, we characterized and investigated the vaccine potential of FgCatL1G against Fasciola gigantica infection in mice. Recombinant mature FgCatL1G (rmFgCatL1G) was expressed in Escherichia coli BL21. The vaccination was performed in Imprinting Control Region (ICR) mice (n=10) by subcutaneous injection with 50μg of rmFgCatL1G combined with Freund's adjuvant. Two weeks after the second boost, mice were infected with 15 metacercariae by the oral route. The percents of protection of rmFgCatL1G vaccine were estimated to be 56.5% and 58.3% when compared with non vaccinated-infected and adjuvant-infected controls, respectively. Antibodies in the immune sera of vaccinated mice were shown by immunoblot to react with the native FgCatL1s in the extract of all stages of parasites and rmFgCatL1H, recombinant pro - FgCatL1 (rpFgCatL1). By immunohistochemistry, the immune sera also reacted with FgCatL1s in the caecal epithelial cells of the parasites. The levels of IgG1 and IgG2a in the immune sera, which are indicative of Th2 and Th1 immune responses, were also increased with IgG1 predominating. The levels of serum glutamic oxaloacetic transaminase (SGOT) and serum glutamic pyruvic transaminase (SGPT) in rmFgCatL1G-immunized group showed no significant difference from the control groups, but pathological lesions of livers in rmFgCatL1G-immunized group showed significant decrease when compared to the control groups. This study indicates that rmFgCatL1G has a vaccine potential against F. gigantica in mice, and this potential will be tested in larger livestock animals. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. ATP6V1G1 — EDRN Public Portal

    Cancer.gov

    ATP6V1G1 is a subunit of vacuolar ATPase (V-ATPase), a multisubunit enzyme. V-ATPase is an enzyme transporter that functions to acidify intracellular compartments in eukaryotic cells. This acidification process is necessary for such intracellular processes as protein sorting, zymogen activation, receptor-mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is ubiquitously expressed and is present in endomembrane organelles such as vacuoles, lysosomes, endosomes, the Golgi apparatus, chromaffin granules and coated vesicles, as well as in the plasma membrane. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain. The V1 domain consists of three A, three B, and two G subunits, as well as a C, D, E, F, and H subunit. The V1 domain contains the ATP catalytic site.

  4. Classical Testing in Functional Linear Models

    PubMed Central

    Kong, Dehan; Staicu, Ana-Maria; Maity, Arnab

    2016-01-01

    We extend four tests common in classical regression - Wald, score, likelihood ratio and F tests - to functional linear regression, for testing the null hypothesis, that there is no association between a scalar response and a functional covariate. Using functional principal component analysis, we re-express the functional linear model as a standard linear model, where the effect of the functional covariate can be approximated by a finite linear combination of the functional principal component scores. In this setting, we consider application of the four traditional tests. The proposed testing procedures are investigated theoretically for densely observed functional covariates when the number of principal components diverges. Using the theoretical distribution of the tests under the alternative hypothesis, we develop a procedure for sample size calculation in the context of functional linear regression. The four tests are further compared numerically for both densely and sparsely observed noisy functional data in simulation experiments and using two real data applications. PMID:28955155

  5. Cacna1g is a genetic modifier of epilepsy caused by mutation of voltage-gated sodium channel Scn2a

    PubMed Central

    Calhoun, Jeffrey D.; Hawkins, Nicole A.; Zachwieja, Nicole J.; Kearney, Jennifer A.

    2016-01-01

    Summary More than 1200 mutations in neuronal voltage-gated sodium channel genes have been identified in patients with several epilepsy syndromes. A common feature of genetic epilepsies is variable expressivity among individuals with the same mutation. The Scn2aQ54 transgenic mouse model has a mutation in Scn2a that results in spontaneous epilepsy. Scn2aQ54 phenotype severity varies depending on the genetic strain background, making it a useful model for identifying and characterizing epilepsy modifier genes. Scn2aQ54 mice on the [C57BL/6JxSJL/J]F1 background exhibit earlier seizure onset, elevated spontaneous seizure frequency, and decreased survival compared to Scn2aQ54 mice congenic on the C57BL/6J strain. Genetic mapping and RNA-Seq analysis identified Cacna1g as a candidate modifier gene at the Moe1 locus, which influences Scn2aQ54 phenotype severity. In this study, we evaluated the modifier potential of Cacna1g, encoding the Cav3.1 voltage-gated calcium channel, by testing whether transgenic alteration of Cacna1g expression modifies severity of the Scn2aQ54 seizure phenotype. Scn2aQ54 mice exhibited increased spontaneous seizure frequency with elevated Cacna1g expression and decreased seizure frequency with decreased Cacna1g expression. These results provide support for Cacna1g as an epilepsy modifier gene and suggest that modulation of Cav3.1 may be an effective therapeutic strategy. PMID:27112236

  6. Cacna1g is a genetic modifier of epilepsy caused by mutation of voltage-gated sodium channel Scn2a.

    PubMed

    Calhoun, Jeffrey D; Hawkins, Nicole A; Zachwieja, Nicole J; Kearney, Jennifer A

    2016-06-01

    More than 1,200 mutations in neuronal voltage-gated sodium channel (VGSC) genes have been identified in patients with several epilepsy syndromes. A common feature of genetic epilepsies is variable expressivity among individuals with the same mutation. The Scn2a(Q54) transgenic mouse model has a mutation in Scn2a that results in spontaneous epilepsy. Scn2a(Q54) phenotype severity varies depending on the genetic strain background, making it a useful model for identifying and characterizing epilepsy modifier genes. Scn2a(Q54) mice on the [C57BL/6JxSJL/J]F1 background exhibit earlier seizure onset, elevated spontaneous seizure frequency, and decreased survival compared to Scn2a(Q54) mice congenic on the C57BL/6J strain. Genetic mapping and RNA-Seq analysis identified Cacna1g as a candidate modifier gene at the Moe1 locus, which influences Scn2a(Q54) phenotype severity. In this study, we evaluated the modifier potential of Cacna1g, encoding the Cav3.1 voltage-gated calcium channel, by testing whether transgenic alteration of Cacna1g expression modifies severity of the Scn2a(Q54) seizure phenotype. Scn2a(Q54) mice exhibited increased spontaneous seizure frequency with elevated Cacna1g expression and decreased seizure frequency with decreased Cacna1g expression. These results provide support for Cacna1g as an epilepsy modifier gene and suggest that modulation of Cav3.1 may be an effective therapeutic strategy. Wiley Periodicals, Inc. © 2016 International League Against Epilepsy.

  7. MATTS- A Step Towards Model Based Testing

    NASA Astrophysics Data System (ADS)

    Herpel, H.-J.; Willich, G.; Li, J.; Xie, J.; Johansen, B.; Kvinnesland, K.; Krueger, S.; Barrios, P.

    2016-08-01

    In this paper we describe a Model Based approach to testing of on-board software and compare it with traditional validation strategy currently applied to satellite software. The major problems that software engineering will face over at least the next two decades are increasing application complexity driven by the need for autonomy and serious application robustness. In other words, how do we actually get to declare success when trying to build applications one or two orders of magnitude more complex than today's applications. To solve the problems addressed above the software engineering process has to be improved at least for two aspects: 1) Software design and 2) Software testing. The software design process has to evolve towards model-based approaches with extensive use of code generators. Today, testing is an essential, but time and resource consuming activity in the software development process. Generating a short, but effective test suite usually requires a lot of manual work and expert knowledge. In a model-based process, among other subtasks, test construction and test execution can also be partially automated. The basic idea behind the presented study was to start from a formal model (e.g. State Machines), generate abstract test cases which are then converted to concrete executable test cases (input and expected output pairs). The generated concrete test cases were applied to an on-board software. Results were collected and evaluated wrt. applicability, cost-efficiency, effectiveness at fault finding, and scalability.

  8. Space Launch System Scale Model Acoustic Test Ignition Overpressure Testing

    NASA Technical Reports Server (NTRS)

    Nance, Donald K.; Liever, Peter A.

    2015-01-01

    The overpressure phenomenon is a transient fluid dynamic event occurring during rocket propulsion system ignition. This phenomenon results from fluid compression of the accelerating plume gas, subsequent rarefaction, and subsequent propagation from the exhaust trench and duct holes. The high-amplitude unsteady fluid-dynamic perturbations can adversely affect the vehicle and surrounding structure. Commonly known as ignition overpressure (IOP), this is an important design-to environment for the Space Launch System (SLS) that NASA is currently developing. Subscale testing is useful in validating and verifying the IOP environment. This was one of the objectives of the Scale Model Acoustic Test (SMAT), conducted at Marshall Space Flight Center (MSFC). The test data quantifies the effectiveness of the SLS IOP suppression system and improves the analytical models used to predict the SLS IOP environments. The reduction and analysis of the data gathered during the SMAT IOP test series requires identification and characterization of multiple dynamic events and scaling of the event waveforms to provide the most accurate comparisons to determine the effectiveness of the IOP suppression systems. The identification and characterization of the overpressure events, the waveform scaling, the computation of the IOP suppression system knockdown factors, and preliminary comparisons to the analytical models are discussed.

  9. Space Launch System Scale Model Acoustic Test Ignition Overpressure Testing

    NASA Technical Reports Server (NTRS)

    Nance, Donald; Liever, Peter; Nielsen, Tanner

    2015-01-01

    The overpressure phenomenon is a transient fluid dynamic event occurring during rocket propulsion system ignition. This phenomenon results from fluid compression of the accelerating plume gas, subsequent rarefaction, and subsequent propagation from the exhaust trench and duct holes. The high-amplitude unsteady fluid-dynamic perturbations can adversely affect the vehicle and surrounding structure. Commonly known as ignition overpressure (IOP), this is an important design-to environment for the Space Launch System (SLS) that NASA is currently developing. Subscale testing is useful in validating and verifying the IOP environment. This was one of the objectives of the Scale Model Acoustic Test, conducted at Marshall Space Flight Center. The test data quantifies the effectiveness of the SLS IOP suppression system and improves the analytical models used to predict the SLS IOP environments. The reduction and analysis of the data gathered during the SMAT IOP test series requires identification and characterization of multiple dynamic events and scaling of the event waveforms to provide the most accurate comparisons to determine the effectiveness of the IOP suppression systems. The identification and characterization of the overpressure events, the waveform scaling, the computation of the IOP suppression system knockdown factors, and preliminary comparisons to the analytical models are discussed.

  10. Do Test Design and Uses Influence Test Preparation? Testing a Model of Washback with Structural Equation Modeling

    ERIC Educational Resources Information Center

    Xie, Qin; Andrews, Stephen

    2013-01-01

    This study introduces Expectancy-value motivation theory to explain the paths of influences from perceptions of test design and uses to test preparation as a special case of washback on learning. Based on this theory, two conceptual models were proposed and tested via Structural Equation Modeling. Data collection involved over 870 test takers of…

  11. Do Test Design and Uses Influence Test Preparation? Testing a Model of Washback with Structural Equation Modeling

    ERIC Educational Resources Information Center

    Xie, Qin; Andrews, Stephen

    2013-01-01

    This study introduces Expectancy-value motivation theory to explain the paths of influences from perceptions of test design and uses to test preparation as a special case of washback on learning. Based on this theory, two conceptual models were proposed and tested via Structural Equation Modeling. Data collection involved over 870 test takers of…

  12. Graphical Models and Computerized Adaptive Testing.

    ERIC Educational Resources Information Center

    Almond, Russell G.; Mislevy, Robert J.

    1999-01-01

    Considers computerized adaptive testing from the perspective of graphical modeling (GM). GM provides methods for making inferences about multifaceted skills and knowledge and for extracting data from complex performances. Provides examples from language-proficiency assessment. (SLD)

  13. Test Model of Mars Landing Radar

    NASA Image and Video Library

    2010-06-11

    The engineering test model for the radar system that will be used during the next landing on Mars is shown here mounted onto a helicopter nose gimbal during a May 12, 2010, test at NASA Dryden Flight Research Center, Edwards, Calif.

  14. Voyager Proof Test Model and Cleanroom

    NASA Image and Video Library

    1977-01-12

    This archival photo shows the Voyager Proof Test Model (in the foreground right of center) undergoing a mechanical preparation and weight center of gravity test at NASA's Jet Propulsion Laboratory, Pasadena, California, on January 12, 1977. https://photojournal.jpl.nasa.gov/catalog/PIA21476

  15. Torsion vehicle model test for automotive vehicle

    NASA Astrophysics Data System (ADS)

    Nor, M. K. Mohd; Ho, C. S.; Ma'at, N.

    2017-04-01

    Torsion vehicle model test of Simple Structural Surfaces (SSS) model for automotive vehicle sedan is proposed in this paper to demonstrate the importance of providing continuous load path within the vehicle structures. The proposed approach is relatively easy to understand as compared to Finite Element Method (FEM). The results prove that the proposed vehicle model test is capable to show that a satisfactory load paths can five a sufficient structural stiffness within the vehicle structure. It is clearly observed that the global torsion stiffness reduces significantly when only one panel is removed from the complete SSS model. The results also five a food agreement with respect to the theoretical hypothesis as the structure is less stiff in torsion in an open section condition. The SSS model and the corresponding torsion test is obviously useful to give an overview of vehicle structural integrity. It can be potentially integrated with FEM to speed up the design process of automotive vehicle.

  16. A defect in the RNA-processing protein HNRPDL causes limb-girdle muscular dystrophy 1G (LGMD1G).

    PubMed

    Vieira, Natássia M; Naslavsky, Michel S; Licinio, Luciana; Kok, Fernando; Schlesinger, David; Vainzof, Mariz; Sanchez, Nury; Kitajima, João Paulo; Gal, Lihi; Cavaçana, Natale; Serafini, Peter R; Chuartzman, Silvia; Vasquez, Cristina; Mimbacas, Adriana; Nigro, Vincenzo; Pavanello, Rita C; Schuldiner, Maya; Kunkel, Louis M; Zatz, Mayana

    2014-08-01

    Limb-girdle muscular dystrophies (LGMD) are a heterogeneous group of genetically determined muscle disorders with a primary or predominant involvement of the pelvic or shoulder girdle musculature. More than 20 genes with autosomal recessive (LGMD2A to LGMD2Q) and autosomal dominant inheritance (LGMD1A to LGMD1H) have been mapped/identified to date. Mutations are known for six among the eight mapped autosomal dominant forms: LGMD1A (myotilin), LGMD1B (lamin A/C), LGMD1C (caveolin-3), LGMD1D (desmin), LGMD1E (DNAJB6), and more recently for LGMD1F (transportin-3). Our group previously mapped the LGMD1G gene at 4q21 in a Caucasian-Brazilian family. We now mapped a Uruguayan family with patients displaying a similar LGMD1G phenotype at the same locus. Whole genome sequencing identified, in both families, mutations in the HNRPDL gene. HNRPDL is a heterogeneous ribonucleoprotein family member, which participates in mRNA biogenesis and metabolism. Functional studies performed in S. cerevisiae showed that the loss of HRP1 (yeast orthologue) had pronounced effects on both protein levels and cell localizations, and yeast proteome revealed dramatic reorganization of proteins involved in RNA-processing pathways. In vivo analysis showed that hnrpdl is important for muscle development in zebrafish, causing a myopathic phenotype when knocked down. The present study presents a novel association between a muscular disorder and a RNA-related gene and reinforces the importance of RNA binding/processing proteins in muscle development and muscle disease. Understanding the role of these proteins in muscle might open new therapeutic approaches for muscular dystrophies.

  17. Mechanisms of plant resistance to 1 g gravity and hypergravity

    NASA Astrophysics Data System (ADS)

    Hoson, Takayuki; Matsumoto, Shouhei; Kumasaki, Saori; Higuchi, Sayoko; Soga, Kouichi; Wakabayashi, Kazuyuki; Hashimoto, Takashi; Suzuki, Masashi; Muranaka, Toshiya; Sakaki, Takeshi

    Resistance to the gravitational force is one of two major graviresponses in plants, comparable to gravitropism. We have examined mechanisms of gravity resistance using hypergravity conditions produced by centrifugation. Under hypergravity conditions, the expression of the gene encoding 3-hydroxy-3-methylglutaryl-Coenzyme A reductase, which catalyzes a reaction producing mevalonic acid, was up-regulated in Arabidopsis hypocotyls, and the level of membrane sterols was kept higher, without influencing the level or composition of other membrane components. Out of sterols, the levels of steryl glycosides and acyl steryl glycosides were greatly increased, suggesting the stimulation of sterol raft formation under hypergravity conditions. On the other hand, the expression of the majority of alphaand beta-tubulin genes was up-regulated and the percentage of cells with longitudinal cortical microtubules was increased by hypergravity. Hypergravity also increased the expression of genes encoding gamma-tubulin complex and katanin transiently, whereas it decreased that encoding various microtubule-associated proteins such as MAP65. The role of membrane sterols and cortical microtubules in gravity resistance was confirmed using Arabidopsis mutants. The analysis with mutants has also revealed that the signal transduction process via sterol rafts is distinct from that via cortical microtubules. These results indicate that membrane sterol rafts and cortical microtubules are deeply and independently involved in maintenance of normal growth capacity against the gravitational force. To confirm that the hypothesis is applicable to plant resistance to 1 g gravity, we will carry out the space experiment. This experiment, termed Resist Wall, is to be performed on the European Modular Cultivation System onboard the International Space Station (ISS). In the Resist Wall experiment, Arabidopsis mutant strains will be cultivated under microgravity and at 1 g conditions on the ISS up to

  18. Transformation model selection by multiple hypotheses testing

    NASA Astrophysics Data System (ADS)

    Lehmann, Rüdiger

    2014-12-01

    Transformations between different geodetic reference frames are often performed such that first the transformation parameters are determined from control points. If in the first place we do not know which of the numerous transformation models is appropriate then we can set up a multiple hypotheses test. The paper extends the common method of testing transformation parameters for significance, to the case that also constraints for such parameters are tested. This provides more flexibility when setting up such a test. One can formulate a general model with a maximum number of transformation parameters and specialize it by adding constraints to those parameters, which need to be tested. The proper test statistic in a multiple test is shown to be either the extreme normalized or the extreme studentized Lagrange multiplier. They are shown to perform superior to the more intuitive test statistics derived from misclosures. It is shown how model selection by multiple hypotheses testing relates to the use of information criteria like AICc and Mallows' , which are based on an information theoretic approach. Nevertheless, whenever comparable, the results of an exemplary computation almost coincide.

  19. Testing a Model of Administrative Job Satisfaction.

    ERIC Educational Resources Information Center

    Volkwein, James Fredericks; Zhou, Ying

    2003-01-01

    Tested a model of administrative job satisfaction using a database of almost 1,200 managers at 120 public and private universities. The robust model explained 54 percent of the variance in overall job satisfaction. Results indicated that few state, campus, and personal characteristics exert direct effects on job satisfaction; they affect work…

  20. Modeling Answer Changes on Test Items

    ERIC Educational Resources Information Center

    van der Linden, Wim J.; Jeon, Minjeong

    2012-01-01

    The probability of test takers changing answers upon review of their initial choices is modeled. The primary purpose of the model is to check erasures on answer sheets recorded by an optical scanner for numbers and patterns that may be indicative of irregular behavior, such as teachers or school administrators changing answer sheets after their…

  1. Retrieval Testing with Hypergeometric Document Models.

    ERIC Educational Resources Information Center

    Wilbur, W. John

    1993-01-01

    Presents a method of modeling the relevance relationship in information retrieval to answer the question of the theoretical limits of certain statistical methods. Hypergeometric probability distribution is used to construct an abstract model of a database of MEDLINE records, and results of tests of vector retrieval methods are reported. (28…

  2. Modeling Answer Changes on Test Items

    ERIC Educational Resources Information Center

    van der Linden, Wim J.; Jeon, Minjeong

    2012-01-01

    The probability of test takers changing answers upon review of their initial choices is modeled. The primary purpose of the model is to check erasures on answer sheets recorded by an optical scanner for numbers and patterns that may be indicative of irregular behavior, such as teachers or school administrators changing answer sheets after their…

  3. Modeling Nonignorable Missing Data in Speeded Tests

    ERIC Educational Resources Information Center

    Glas, Cees A. W.; Pimentel, Jonald L.

    2008-01-01

    In tests with time limits, items at the end are often not reached. Usually, the pattern of missing responses depends on the ability level of the respondents; therefore, missing data are not ignorable in statistical inference. This study models data using a combination of two item response theory (IRT) models: one for the observed response data and…

  4. SOFIA telescope modal survey test and test-model correlation

    NASA Astrophysics Data System (ADS)

    Keas, Paul; Brewster, Rick; Guerra, Jorge; Lampater, Ulrich; Kärcher, Hans; Teufel, Stefan; Wagner, Jörg

    2010-07-01

    The NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA) employs a 2.5-meter reflector telescope in a Boeing 747SP. The telescope is housed in an open cavity and will be subjected to aeroacoustic and inertial disturbances. The image stability goal for SOFIA is 0.2 arc-seconds (RMS). Throughout the development phase of the project, analytical models were employed to predict the image stability performance of the telescope, and to evaluate pointing performance improvement measures. These analyses clearly demonstrated that key aspects which determined performance were: 1) Disturbance environment and relevant load-paths 2) Telescope modal behavior 3) Sensor and actuator placement 4) Control algorithm design The SOFIA program is now entering an exciting phase in which the characteristics of the telescope and the cavity environment are being verified through ground and airborne testing. A modal survey test (MST) was conducted in early 2008 to quantify the telescope modal behavior. We will give a brief overview of analytical methods which have been employed to assess/improve the pointing stability performance of the SOFIA telescope. In this context, we will describe the motivation for the MST, and the pre-test analysis which determined the modes of interest and the required MST sensor/shaker placement. A summary will then be given of the FEM-test correlation effort, updated end-to-end simulation results, and actual data coming from telescope activation test flights.

  5. Hydrodynamic Tests of Models of Seaplane Floats

    NASA Technical Reports Server (NTRS)

    Eula, Antonio

    1935-01-01

    This report contains the results of tank tests carried out at free trim on seventeen hulls and floats of various types. The data as to the weight on water, trim, and relative resistance for each model are plotted nondimensionally and are referenced both to the total weight and to the weight on water. Despite the fact that the experiments were not made systematically, a study of the models and of the test data permits nevertheless some general deductions regarding the forms of floats and their resistance. One specific conclusion is that the best models have a maximum relative resistance not exceeding 20 percent of the total weight.

  6. SOD1-G93A mice exhibit muscle-fiber-type-specific decreases in glucose uptake in the absence of whole-body changes in metabolism.

    PubMed

    Smittkamp, Susan E; Morris, Jill K; Bomhoff, Gregory L; Chertoff, Mark E; Geiger, Paige C; Stanford, John A

    2014-01-01

    Skeletal muscles play an important role in systemic glucose homeostasis and are purported to be the origin of the altered metabolic state observed in amyotrophic lateral sclerosis (ALS). The purpose of this study was to evaluate whole-body and muscle-specific glucose metabolism in the SOD1-G93A mouse model of ALS. We assessed glucose tolerance in early-, middle-, and late-stage SOD1-G93A and control mice using an intraperitoneal glucose tolerance test. We then measured the respiratory exchange ratio (CO2 production/O2 consumption) as a function of fasting and feeding using indirect calorimetry in a subset of male mice at these time points. Finally, muscles from all mice were harvested to evaluate basal and insulin-stimulated glucose transport in fast- and slow-twitch muscles. No changes in systemic glucose clearance were observed in SOD1-G93A mice at any stage, nor were there changes in fasting insulin levels. Indirect calorimetry revealed an increase in the respiratory exchange ratio during the fed state at middle, but not at early or late stages of disease. Middle-stage SOD1-G93A mice exhibited decreased insulin-stimulated glucose uptake in fast-twitch, but not slow-twitch, skeletal muscle. Late-stage SOD1-G93A mice exhibited decreased insulin-stimulated glucose uptake in both fast- and slow-twitch muscle, as well as increased basal (non-insulin-stimulated) glucose uptake. These results suggest that alterations in muscle metabolism occur in a fiber-type-specific manner in ALS, but do not necessarily lead to whole-body metabolic changes in SOD1-G93A mice. Copyright © 2013 S. Karger AG, Basel

  7. Water Model Tests for Semirigid Airships

    NASA Technical Reports Server (NTRS)

    Tuckerman, L.B.

    1926-01-01

    The design of complicated structures often presents problems of extreme difficulty which are frequently insoluble. In many cases, however, the solution can be obtained by tests on suitable models. These model tests are becoming so important a part of the design of new engineering structures that their theory has become a necessary part of an engineer's knowledge. For balloons and airships water models are used. These are models about 1/30 the size of the airship hung upside down and filled with water under pressure. The theory shows that the stresses in such a model are the same as in the actual airship. In the design of the Army Semirigid Airship RS-1 no satisfactory way was found to calculate the stresses in the keel due to the changing shape of the bag. For this purpose a water model with a flexible keel was built and tested. This report gives the theory of the design, construction, and testing of such a water model.

  8. Kinematic tests of exotic flat cosmological models

    SciTech Connect

    Charlton, J.C.; Turner, M.S.

    1986-05-01

    Theoretical prejudice and inflationary models of the very early Universe strongly favor the flat, Einstein-deSitter model of the Universe. At present the observational data conflict with this prejudice. This conflict can be resolved by considering flat models of the Universe which possess a smooth component by energy density. We study in detail the kinematics of such models, where the smooth component is relativistic particles, a cosmological term, a network of light strings, or fast-moving, light strings. We also discuss the observational tests which can be used to discriminate between these models. These tests include the magnitude-redshift, lookback time-redshift, angular size-redshift, and comoving volume-redshift diagrams and the growth of density fluctuations.

  9. Kinematic tests of exotic flat cosmological models

    NASA Technical Reports Server (NTRS)

    Charlton, Jane C.; Turner, Michael S.

    1987-01-01

    Theoretical prejudice and inflationary models of the very early universe strongly favor the flat, Einstein-de Sitter model of the universe. At present the observational data conflict with this prejudice. This conflict can be resolved by considering flat models of the universe which posses a smooth component of energy density. The kinematics of such models, where the smooth component is relativistic particles, a cosmological term, a network of light strings, or fast-moving, light strings is studied in detail. The observational tests which can be used to discriminate between these models are also discussed. These tests include the magnitude-redshift, lookback time-redshift, angular size-redshift, and comoving volume-redshift diagrams and the growth of density fluctuations.

  10. Kinematic tests of exotic flat cosmological models

    SciTech Connect

    Charlton, J.C.; Turner, M.S.

    1987-02-01

    Theoretical prejudice and inflationary models of the very early universe strongly favor the flat, Einstein-de Sitter model of the universe. At present the observational data conflict with this prejudice. This conflict can be resolved by considering flat models of the universe which posses a smooth component of energy density. The kinematics of such models, where the smooth component is relativistic particles, a cosmological term, a network of light strings, or fast-moving, light strings is studied in detail. The observational tests which can be used to discriminate between these models are also discussed. These tests include the magnitude-redshift, lookback time-redshift, angular size-redshift, and comoving volume-redshift diagrams and the growth of density fluctuations. 58 references.

  11. A 'Turing' Test for Landscape Evolution Models

    NASA Astrophysics Data System (ADS)

    Parsons, A. J.; Wise, S. M.; Wainwright, J.; Swift, D. A.

    2008-12-01

    Resolving the interactions among tectonics, climate and surface processes at long timescales has benefited from the development of computer models of landscape evolution. However, testing these Landscape Evolution Models (LEMs) has been piecemeal and partial. We argue that a more systematic approach is required. What is needed is a test that will establish how 'realistic' an LEM is and thus the extent to which its predictions may be trusted. We propose a test based upon the Turing Test of artificial intelligence as a way forward. In 1950 Alan Turing posed the question of whether a machine could think. Rather than attempt to address the question directly he proposed a test in which an interrogator asked questions of a person and a machine, with no means of telling which was which. If the machine's answer could not be distinguished from those of the human, the machine could be said to demonstrate artificial intelligence. By analogy, if an LEM cannot be distinguished from a real landscape it can be deemed to be realistic. The Turing test of intelligence is a test of the way in which a computer behaves. The analogy in the case of an LEM is that it should show realistic behaviour in terms of form and process, both at a given moment in time (punctual) and in the way both form and process evolve over time (dynamic). For some of these behaviours, tests already exist. For example there are numerous morphometric tests of punctual form and measurements of punctual process. The test discussed in this paper provides new ways of assessing dynamic behaviour of an LEM over realistically long timescales. However challenges remain in developing an appropriate suite of challenging tests, in applying these tests to current LEMs and in developing LEMs that pass them.

  12. Integrated radionuclide release: tests and model development (integrated testing)

    SciTech Connect

    Viani, B

    1995-08-07

    The Department of Energy's Yucca Mountain Site Characterization Project (YMP) is evaluating a site at Yucca Mountain, Nevada as a potential repository for the disposal of high-level nuclear waste. Credible bounding estimates of the type, concentration, and nature of the radionuclides that might potentially escape the engineered barrier system/near field environment (EBS/NFE) (i.e., the source term) are necessary prerequisites to assessing the expected performance of a po- tential repository. Estimating the source term will require a combination of experimental and modeling tasks that are designed to assess the release of radionclides from the waste form and their transport through and interaction with the components of the EBS/NFE. The Integrated Radionuclidc Release: Tests and Model Development activity (Integrated Testing) at Lawrence Liver-more National Laboratory (LLNL) is an experimental and modeling activity that is specifically concerned with radionuclide transport through and interaction with the compo- nents of the EBS/NFE. As such, this activity is the link b!etween waste-form degradation activities and far-field transport activities. Performance analysis of the EBS/NFE subsystem is an important component of the total system performance analyses (TSPA) that will be used to evaluate reposi- tory performance.

  13. Molecular Sieve Bench Testing and Computer Modeling

    NASA Technical Reports Server (NTRS)

    Mohamadinejad, Habib; DaLee, Robert C.; Blackmon, James B.

    1995-01-01

    The design of an efficient four-bed molecular sieve (4BMS) CO2 removal system for the International Space Station depends on many mission parameters, such as duration, crew size, cost of power, volume, fluid interface properties, etc. A need for space vehicle CO2 removal system models capable of accurately performing extrapolated hardware predictions is inevitable due to the change of the parameters which influences the CO2 removal system capacity. The purpose is to investigate the mathematical techniques required for a model capable of accurate extrapolated performance predictions and to obtain test data required to estimate mass transfer coefficients and verify the computer model. Models have been developed to demonstrate that the finite difference technique can be successfully applied to sorbents and conditions used in spacecraft CO2 removal systems. The nonisothermal, axially dispersed, plug flow model with linear driving force for 5X sorbent and pore diffusion for silica gel are then applied to test data. A more complex model, a non-darcian model (two dimensional), has also been developed for simulation of the test data. This model takes into account the channeling effect on column breakthrough. Four FORTRAN computer programs are presented: a two-dimensional model of flow adsorption/desorption in a packed bed; a one-dimensional model of flow adsorption/desorption in a packed bed; a model of thermal vacuum desorption; and a model of a tri-sectional packed bed with two different sorbent materials. The programs are capable of simulating up to four gas constituents for each process, which can be increased with a few minor changes.

  14. Modeling minimal residual disease (MRD)-testing.

    PubMed

    Butturini, Anna; Klein, John; Gale, Robert Peter

    2003-04-01

    There is considerable effort to develop more sensitive methods to detect minimal residual disease (MRD) in bone marrow and blood samples of persons with cancer. Results of MRD-testing are used to predict clinical outcome and determine if more anti-cancer therapy is needed. Mathematical models were developed to assess factors affecting sensitivity and specificity of MRD-testing at diverse cancer cell prevalences. Modeling results and predictions were compared to results of large published studies.Accuracy of MRD-testing depends on cancer cell prevalence and distribution in the blood or bone marrow of the subject, sensitivity and specificity of the MRD-test and sample size. In subjects with low cancer cell prevalences (< or = 10(-4)) results of MRD testing are likely inaccurate. Increasingly sensitive MRD-tests are only marginally useful; the major obstacle to accuracy is inadequate sampling. Increasing sensitivity of methods to detect MRD is unlikely sufficient to increase accuracy of MRD-testing. In contrast, increased sampling (size and frequency) and assigning a high cut-off value (for example, > or = 10(-3)) to declare a MRD-test positive will increase sensitivity and specificity, respectively.

  15. APOL1-G1 in Nephrocytes Induces Hypertrophy and Accelerates Cell Death.

    PubMed

    Fu, Yulong; Zhu, Jun-Yi; Richman, Adam; Zhang, Yi; Xie, Xuefang; Das, Jharna R; Li, Jinliang; Ray, Patricio E; Han, Zhe

    2017-04-01

    People of African ancestry carrying certain APOL1 mutant alleles are at elevated risk of developing renal diseases. However, the mechanisms underlying APOL1-associated renal diseases are unknown. Because the APOL1 gene is unique to humans and some primates, new animal models are needed to understand the function of APOL1 in vivo We generated transgenic Drosophila fly lines expressing the human APOL1 wild type allele (G0) or the predominant APOL1 risk allele (G1) in different tissues. Ubiquitous expression of APOL1 G0 or G1 in Drosophila induced lethal phenotypes, and G1 was more toxic than was G0. Selective expression of the APOL1 G0 or G1 transgene in nephrocytes, fly cells homologous to mammalian podocytes, induced increased endocytic activity and accumulation of hemolymph proteins, dextran particles, and silver nitrate. As transgenic flies with either allele aged, nephrocyte function declined, cell size increased, and nephrocytes died prematurely. Compared with G0-expressing cells, however, G1-expressing cells showed more dramatic phenotypes, resembling those observed in cultured mammalian podocytes overexpressing APOL1-G1. Expressing the G0 or G1 APOL1 transgene in nephrocytes also impaired the acidification of organelles. We conclude that expression of an APOL1 transgene initially enhances nephrocyte function, causing hypertrophy and subsequent cell death. This new Drosophila model uncovers a novel mechanism by which upregulated expression of APOL1-G1 could precipitate renal disease in humans. Furthermore, this model may facilitate the identification of APOL1-interacting molecules that could serve as new drug targets to treat APOL1-associated renal diseases.

  16. Testing the dipole modulation model in CMBR

    SciTech Connect

    Rath, Pranati K.; Jain, Pankaj E-mail: pkjain@iitk.ac.in

    2013-12-01

    The hemispherical power asymmetry, observed in the CMBR data, has generally been interpreted in terms of the dipole modulation model for the temperature fluctuations. Here we point out that this model leads to several predictions, which can be directly tested in the current data. We suggest tests of the hemispherical power asymmetry both in real and multipole space. We find a significant signal of the dipole modulation model in WMAP and PLANCK data with our tests. The dipole amplitude and direction also agrees, within errors, with earlier results based on hemispherical analysis in multipole space. We also find evidence that the effective dipole modulation amplitude increases with the multipole l in the range l = 2−64.

  17. Pile Model Tests Using Strain Gauge Technology

    NASA Astrophysics Data System (ADS)

    Krasiński, Adam; Kusio, Tomasz

    2015-09-01

    Ordinary pile bearing capacity tests are usually carried out to determine the relationship between load and displacement of pile head. The measurement system required in such tests consists of force transducer and three or four displacement gauges. The whole system is installed at the pile head above the ground level. This approach, however, does not give us complete information about the pile-soil interaction. We can only determine the total bearing capacity of the pile, without the knowledge of its distribution into the shaft and base resistances. Much more information can be obtained by carrying out a test of instrumented pile equipped with a system for measuring the distribution of axial force along its core. In the case of pile model tests the use of such measurement is difficult due to small scale of the model. To find a suitable solution for axial force measurement, which could be applied to small scale model piles, we had to take into account the following requirements: - a linear and stable relationship between measured and physical values, - the force measurement accuracy of about 0.1 kN, - the range of measured forces up to 30 kN, - resistance of measuring gauges against aggressive counteraction of concrete mortar and against moisture, - insensitivity to pile bending, - economical factor. These requirements can be fulfilled by strain gauge sensors if an appropriate methodology is used for test preparation (Hoffmann [1]). In this paper, we focus on some aspects of the application of strain gauge sensors for model pile tests. The efficiency of the method is proved on the examples of static load tests carried out on SDP model piles acting as single piles and in a group.

  18. Pile Model Tests Using Strain Gauge Technology

    NASA Astrophysics Data System (ADS)

    Krasiński, Adam; Kusio, Tomasz

    2015-09-01

    Ordinary pile bearing capacity tests are usually carried out to determine the relationship between load and displacement of pile head. The measurement system required in such tests consists of force transducer and three or four displacement gauges. The whole system is installed at the pile head above the ground level. This approach, however, does not give us complete information about the pile-soil interaction. We can only determine the total bearing capacity of the pile, without the knowledge of its distribution into the shaft and base resistances. Much more information can be obtained by carrying out a test of instrumented pile equipped with a system for measuring the distribution of axial force along its core. In the case of pile model tests the use of such measurement is difficult due to small scale of the model. To find a suitable solution for axial force measurement, which could be applied to small scale model piles, we had to take into account the following requirements: - a linear and stable relationship between measured and physical values, - the force measurement accuracy of about 0.1 kN, - the range of measured forces up to 30 kN, - resistance of measuring gauges against aggressive counteraction of concrete mortar and against moisture, - insensitivity to pile bending, - economical factor. These requirements can be fulfilled by strain gauge sensors if an appropriate methodology is used for test preparation (Hoffmann [1]). In this paper, we focus on some aspects of the application of strain gauge sensors for model pile tests. The efficiency of the method is proved on the examples of static load tests carried out on SDP model piles acting as single piles and in a group.

  19. Simulation of a Model Tank Gunnery Test

    DTIC Science & Technology

    1979-03-01

    strong claim for content and construct validity (Wheaton et al., 1978; Guion & Ironson, 1978) a test based on the model set of livefire exercises is...considered highly unlikely because of the effort made to insure the content validity of the simulated test ( Guion & Ironson, 1978). Replicated designs. In...including physically measuring and "pasting up" targets, or using video cameras equipped with telephoto lenses stationed in an overwatch position

  20. A Method to Test Model Calibration Techniques

    SciTech Connect

    Judkoff, Ron; Polly, Ben; Neymark, Joel

    2016-08-26

    This paper describes a method for testing model calibration techniques. Calibration is commonly used in conjunction with energy retrofit audit models. An audit is conducted to gather information about the building needed to assemble an input file for a building energy modeling tool. A calibration technique is used to reconcile model predictions with utility data, and then the 'calibrated model' is used to predict energy savings from a variety of retrofit measures and combinations thereof. Current standards and guidelines such as BPI-2400 and ASHRAE-14 set criteria for 'goodness of fit' and assume that if the criteria are met, then the calibration technique is acceptable. While it is logical to use the actual performance data of the building to tune the model, it is not certain that a good fit will result in a model that better predicts post-retrofit energy savings. Therefore, the basic idea here is that the simulation program (intended for use with the calibration technique) is used to generate surrogate utility bill data and retrofit energy savings data against which the calibration technique can be tested. This provides three figures of merit for testing a calibration technique, 1) accuracy of the post-retrofit energy savings prediction, 2) closure on the 'true' input parameter values, and 3) goodness of fit to the utility bill data. The paper will also discuss the pros and cons of using this synthetic surrogate data approach versus trying to use real data sets of actual buildings.

  1. Immune response in peripheral axons delays disease progression in SOD1(G93A) mice.

    PubMed

    Nardo, Giovanni; Trolese, Maria Chiara; de Vito, Giuseppe; Cecchi, Roberta; Riva, Nilo; Dina, Giorgia; Heath, Paul R; Quattrini, Angelo; Shaw, Pamela J; Piazza, Vincenzo; Bendotti, Caterina

    2016-10-07

    Increasing evidence suggests that the immune system has a beneficial role in the progression of amyotrophic lateral sclerosis (ALS) although the mechanism remains unclear. Recently, we demonstrated that motor neurons (MNs) of C57SOD1(G93A) mice with slow disease progression activate molecules classically involved in the cross-talk with the immune system. This happens a lot less in 129SvSOD1(G93A) mice which, while expressing the same amount of transgene, had faster disease progression and earlier axonal damage. The present study investigated whether and how the immune response is involved in the preservation of motor axons in the mouse model of familial ALS with a more benign disease course. First, the extent of axonal damage, Schwann cell proliferation, and neuromuscular junction (NMJ) denervation were compared between the two ALS mouse models at the disease onset. Then, we compared the expression levels of different immune molecules, the morphology of myelin sheaths, and the presence of blood-derived immune cell infiltrates in the sciatic nerve of the two SOD1G93A mouse strains using immunohistochemical, immunoblot, quantitative reverse transcription PCR, and rotating-polarization Coherent Anti-Stokes Raman Scattering techniques. Muscle denervation, axonal dysregulation, and myelin disruption together with reduced Schwann cell proliferation are prominent in 129SvSOD1(G93A) compared to C57SOD1(G93A) mice at the disease onset, and this correlates with a faster disease progression in the first strain. On the contrary, a striking increase of immune molecules such as CCL2, MHCI, and C3 was seen in sciatic nerves of slow progressor C57SOD1(G93A) mice and this was accompanied by heavy infiltration of CD8(+) T lymphocytes and macrophages. These phenomena were not detectable in the peripheral nervous system of fast-progressing mice. These data show for the first time that damaged MNs in SOD1-related ALS actively recruit immune cells in the peripheral nervous system to

  2. Unit testing, model validation, and biological simulation

    PubMed Central

    Watts, Mark D.; Ghayoomie, S. Vahid; Larson, Stephen D.; Gerkin, Richard C.

    2016-01-01

    The growth of the software industry has gone hand in hand with the development of tools and cultural practices for ensuring the reliability of complex pieces of software. These tools and practices are now acknowledged to be essential to the management of modern software. As computational models and methods have become increasingly common in the biological sciences, it is important to examine how these practices can accelerate biological software development and improve research quality. In this article, we give a focused case study of our experience with the practices of unit testing and test-driven development in OpenWorm, an open-science project aimed at modeling Caenorhabditis elegans. We identify and discuss the challenges of incorporating test-driven development into a heterogeneous, data-driven project, as well as the role of model validation tests, a category of tests unique to software which expresses scientific models. PMID:27635225

  3. Mathematical Modelling of the Infusion Test

    NASA Astrophysics Data System (ADS)

    Cieslicki, Krzysztof

    2007-01-01

    The objective of this paper was to improve the well established in clinical practice Marmarou model for intracranial volume-pressure compensation by adding the pulsatile components. It was demonstrated that complicated pulsation and growth in intracranial pressure during infusion test could be successfully modeled by the relatively simple analytical expression derived in this paper. The CSF dynamics were tested in 25 patients with clinical symptoms of hydrocephalus. Basing on the frequency spectrum of the patient's baseline pressure and identified parameters of CSF dynamic, for each patient an "ideal" infusion test curve free from artefacts and slow waves was simulated. The degree of correlation between simulated and real curves obtained from clinical observations gave insight into the adequacy of assumptions of Marmarou model. The proposed method of infusion tests analysis designates more exactly the value of the reference pressure, which is usually treated as a secondary and of uncertain significance. The properly identified value of the reference pressure decides on the degree of pulsation amplitude growth during IT, as well as on the value of elastance coefficient. The artificially generated tests with various pulsation components were also applied to examine the correctness of the used algorithm of identification of the original Marmarou model parameters.

  4. Impact of uncertainty on modeling and testing

    NASA Technical Reports Server (NTRS)

    Coleman, Hugh W.; Brown, Kendall K.

    1995-01-01

    A thorough understanding of the uncertainties associated with the modeling and testing of the Space Shuttle Main Engine (SSME) Engine will greatly aid decisions concerning hardware performance and future development efforts. This report will describe the determination of the uncertainties in the modeling and testing of the Space Shuttle Main Engine test program at the Technology Test Bed facility at Marshall Space Flight Center. Section 2 will present a summary of the uncertainty analysis methodology used and discuss the specific applications to the TTB SSME test program. Section 3 will discuss the application of the uncertainty analysis to the test program and the results obtained. Section 4 presents the results of the analysis of the SSME modeling effort from an uncertainty analysis point of view. The appendices at the end of the report contain a significant amount of information relative to the analysis, including discussions of venturi flowmeter data reduction and uncertainty propagation, bias uncertainty documentations, technical papers published, the computer code generated to determine the venturi uncertainties, and the venturi data and results used in the analysis.

  5. Accuracy tests of the tessellated SLBM model

    SciTech Connect

    Ramirez, A L; Myers, S C

    2007-07-20

    We have compared the Seismic Location Base Model (SLBM) tessellated model (version 2.0 Beta, posted July 3, 2007) with the GNEMRE Unified Model. The comparison is done on a layer/depth-by-layer/depth and layer/velocity-by-layer/velocity comparison. The SLBM earth model is defined on a tessellation that spans the globe at a constant resolution of about 1 degree (Ballard, 2007). For the tests, we used the earth model in file ''unified{_}iasp.grid''. This model contains the top 8 layers of the Unified Model (UM) embedded in a global IASP91 grid. Our test queried the same set of nodes included in the UM model file. To query the model stored in memory, we used some of the functionality built into the SLBMInterface object. We used the method get InterpolatedPoint() to return desired values for each layer at user-specified points. The values returned include: depth to the top of each layer, layer velocity, layer thickness and (for the upper-mantle layer) velocity gradient. The SLBM earth model has an extra middle crust layer whose values are used when Pg/Lg phases are being calculated. This extra layer was not accessed by our tests. Figures 1 to 8 compare the layer depths, P velocities and P gradients in the UM and SLBM models. The figures show results for the three sediment layers, three crustal layers and the upper mantle layer defined in the UM model. Each layer in the models (sediment1, sediment2, sediment3, upper crust, middle crust, lower crust and upper mantle) is shown on a separate figure. The upper mantle P velocity and gradient distribution are shown on Figures 7 and 8. The left and center images in the top row of each figure is the rendering of depth to the top of the specified layer for the UM and SLBM models. When a layer has zero thickness, its depth is the same as that of the layer above. The right image in the top row is the difference between in layer depth for the UM and SLBM renderings. The left and center images in the bottom row of the figures are

  6. 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.

  7. Development of an unsteady aerodynamics model to improve correlation of computed blade stresses with test data

    NASA Technical Reports Server (NTRS)

    Gangwani, S. T.

    1985-01-01

    A reliable rotor aeroelastic analysis operational that correctly predicts the vibration levels for a helicopter is utilized to test various unsteady aerodynamics models with the objective of improving the correlation between test and theory. This analysis called Rotor Aeroelastic Vibration (RAVIB) computer program is based on a frequency domain forced response analysis which utilizes the transfer matrix techniques to model helicopter/rotor dynamic systems of varying degrees of complexity. The results for the AH-1G helicopter rotor were compared with the flight test data during high speed operation and they indicated a reasonably good correlation for the beamwise and chordwise blade bending moments, but for torsional moments the correlation was poor. As a result, a new aerodynamics model based on unstalled synthesized data derived from the large amplitude oscillating airfoil experiments was developed and tested.

  8. Modelling the impact testing of prescription lenses.

    PubMed

    McAuliffe, P J; Truss, R W; Pittolo, M

    1997-04-01

    Lenses are tested in an impact test in which a steel ball is dropped from a height onto the centre of the lens. This causes the lens to deform until the stress in the lens reaches a point at which fracture occurs. A survey of the literature was carried out and analytical models of the load/deflection and of the deflection/stress relationships were selected. A mathematical model of the impact test on lenses was developed. This model consisted of calculating the load-deflection relationship of a lens loaded at a central point, combined with calculating the deflection at which fracture occurred. From this model the impact energy required to deform a lens to fracture was obtained. This was held to be equal to the minimum kinetic energy of an impactor, less losses, that would be needed to cause lens fracture. As the losses are small, the calculated energy was used as an estimate of the impact strength of the lens. These values were then compared to those established by experiment. The impact energies predicted by the model were a close approximation of the experimental results for the lenses tested.

  9. Flight Test Maneuvers for Efficient Aerodynamic Modeling

    NASA Technical Reports Server (NTRS)

    Morelli, Eugene A.

    2011-01-01

    Novel flight test maneuvers for efficient aerodynamic modeling were developed and demonstrated in flight. Orthogonal optimized multi-sine inputs were applied to aircraft control surfaces to excite aircraft dynamic response in all six degrees of freedom simultaneously while keeping the aircraft close to chosen reference flight conditions. Each maneuver was designed for a specific modeling task that cannot be adequately or efficiently accomplished using conventional flight test maneuvers. All of the new maneuvers were first described and explained, then demonstrated on a subscale jet transport aircraft in flight. Real-time and post-flight modeling results obtained using equation-error parameter estimation in the frequency domain were used to show the effectiveness and efficiency of the new maneuvers, as well as the quality of the aerodynamic models that can be identified from the resultant flight data.

  10. [Thurstone model application to difference sensory tests].

    PubMed

    Angulo, Ofelia; O'Mahony, Michael

    2009-12-01

    Part of understanding why judges perform better on some difference tests than others requires an understanding of how information coming from the mouth to the brain is processed. For some tests it is processed more efficiently than others. This is described by what has been called Thurstonian modeling. This brief review introduces the concepts and ideas involved in Thurstonian modeling as applied to sensory difference measurement. It summarizes the literature concerned with the theorizing and confirmation of Thurstonian models. It introduces the important concept of stimulus variability and the fundamental measure of sensory difference: d'. It indicates how the paradox of discriminatory non-discriminators, which had puzzled researchers for years, can be simply explained using the model. It considers how memory effects and the complex interactions in the mouth can reduce d' by increasing the variance of sensory distributions.

  11. Tritium transfer in pigs - A model test

    SciTech Connect

    Melintescu, A.; Galeriu, D.

    2008-07-15

    In the frame of IAEA EMRAS (Environmental Modelling for Radiation Safety) programme, there was developed a scenario for models ' testing starting with unpublished data for a sow fed with OBT for 84 days. The scenario includes model predictions for the dynamics of tritium in urine and faeces and HTO and OBT in organs at sacrifice. There have been done two inter-comparison exercises and most of the models succeeded to give predictions better than a factor 3 to 5, excepting faeces. There has been done an analysis of models' structure, performance and limits in order to be able to build a model of moderate complexity with a reliable predictive power, able to be applied for human dosimetry, also, when OBT data are missing. (authors)

  12. Component testing for dynamic model verification

    NASA Technical Reports Server (NTRS)

    Hasselman, T. K.; Chrostowski, J. D.

    1984-01-01

    Dynamic model verification is the process whereby an analytical model of a dynamic system is compared with experimental data, adjusted if necessary to bring it into agreement with the data, and then qualified for future use in predicting system response in a different dynamic environment. These are various ways to conduct model verification. The approach taken here employs Bayesian statistical parameter estimation. Unlike curve fitting, whose objective is to minimize the difference between some analytical function and a given quantity of test data (or curve), Bayesian estimation attempts also to minimize the difference between the parameter values of that funciton (the model) and their initial estimates, in a least squares sense. The objectives of dynamic model verification, therefore, are to produce a model which: (1) is in agreement with test data; (2) will assist in the interpretation of test data; (3) can be used to help verify a design; (4) will reliably predict performance; and (5) in the case of space structures, will facilitate dynamic control.

  13. Equating Tests With the Rasch Model.

    ERIC Educational Resources Information Center

    Kreines, David C.; Mead, Ronald J.

    An explanation is given of what is meant by "sample-free" item calibration and by "item-free" person measurement as these terms are applied to the one-parameter logistic test theory model of Georg Rasch. When the difficulty of an item is calibrated separately for two different samples the results may differ; but, according the…

  14. Model anchor tests in cohesionless soil

    SciTech Connect

    Walker, G.R.; Taylor, R.J.

    1983-05-01

    Tandem (piggyback), parallel, and single model anchor tests have been performed in cohesionless soil. Tandem anchor arrangements have been found that result in a tandem system capacity that exceeds twice the capacity of a single anchor. These methods are operationally feasible and offer the potential for anchor weight savings.

  15. Binomial Test Models and Item Difficulty.

    ERIC Educational Resources Information Center

    van der Linden, Wim J.

    1979-01-01

    The restrictions on item difficulties that must be met when binomial models are applied to domain-referenced testing are examined. Both a deterministic and a stochastic conception of item responses are discussed with respect to difficulty and Guttman-type items. (Author/BH)

  16. Equating Tests under the Graded Response Model.

    ERIC Educational Resources Information Center

    Baker, Frank B.

    1992-01-01

    The procedure of M.L. Stocking and F.M. Lord (1983) for computing equating coefficients for tests having dichotomously scored items is extended to the case of graded response items. A system of equations for obtaining the equating coefficients under the graded response model is derived. (SLD)

  17. CPAS Parachute Testing, Model Development, & Verification

    NASA Technical Reports Server (NTRS)

    Romero, Leah M.

    2013-01-01

    Capsule Parachute Assembly System (CPAS) is the human rated parachute system for the Orion vehicle used during re-entry. Similar to Apollo parachute design. Human rating requires additional system redundancy. A Government Furnished Equipment (GFE) project responsible for: Design; Development testing; Performance modeling; Fabrication; Qualification; Delivery

  18. Testing Three Models for the Sleeper Effect.

    ERIC Educational Resources Information Center

    Allen, Mike; Stiff, James B.

    1989-01-01

    Uses meta-analysis to test three models of the "sleeper" effect (a theory proposing that in the long term low credible sources may actually attain greater attitude change in message recipients than high credible sources). Concludes that the sleeper effect does exist, and offers suggestions for practitioners and theorists. (SR)

  19. Testing of a steel containment vessel model

    SciTech Connect

    Luk, V.K.; Hessheimer, M.F.; Matsumoto, T.; Komine, K.; Costello, J.F.

    1997-04-01

    A mixed-scale containment vessel model, with 1:10 in containment geometry and 1:4 in shell thickness, was fabricated to represent an improved, boiling water reactor (BWR) Mark II containment vessel. A contact structure, installed over the model and separated at a nominally uniform distance from it, provided a simplified representation of a reactor shield building in the actual plant. This paper describes the pretest preparations and the conduct of the high pressure test of the model performed on December 11-12, 1996. 4 refs., 2 figs.

  20. Mechanism test bed. Flexible body model report

    NASA Technical Reports Server (NTRS)

    Compton, Jimmy

    1991-01-01

    The Space Station Mechanism Test Bed is a six degree-of-freedom motion simulation facility used to evaluate docking and berthing hardware mechanisms. A generalized rigid body math model was developed which allowed the computation of vehicle relative motion in six DOF due to forces and moments from mechanism contact, attitude control systems, and gravity. No vehicle size limitations were imposed in the model. The equations of motion were based on Hill's equations for translational motion with respect to a nominal circular earth orbit and Newton-Euler equations for rotational motion. This rigid body model and supporting software were being refined.

  1. Testing models of tree canopy structure

    SciTech Connect

    Martens, S.N. )

    1994-06-01

    Models of tree canopy structure are difficult to test because of a lack of data which are suitability detailed. Previously, I have made three-dimensional reconstructions of individual trees from measured data. These reconstructions have been used to test assumptions about the dispersion of canopy elements in two- and three-dimensional space. Lacunarity analysis has also been used to describe the texture of the reconstructed canopies. Further tests regarding models of the nature of tree branching structures have been made. Results using probability distribution functions for branching measured from real trees show that branching in Juglans is not Markovian. Specific constraints or rules are necessary to achieve simulations of branching structure which are faithful to the originally measured trees.

  2. Advanced air revitalization system modeling and testing

    NASA Technical Reports Server (NTRS)

    Dall-Baumann, Liese; Jeng, Frank; Christian, Steve; Edeer, Marybeth; Lin, Chin

    1990-01-01

    To support manned lunar and Martian exploration, an extensive evaluation of air revitalization subsystems (ARS) is being conducted. The major operations under study include carbon dioxide removal and reduction; oxygen and nitrogen production, storage, and distribution; humidity and temperature control; and trace contaminant control. A comprehensive analysis program based on a generalized block flow model was developed to facilitate the evaluation of various processes and their interaction. ASPEN PLUS was used in modelling carbon dioxide removal and reduction. Several life support test stands were developed to test new and existing technologies for their potential applicability in space. The goal was to identify processes which use compact, lightweight equipment and maximize the recovery of oxygen and water. The carbon dioxide removal test stands include solid amine/vacuum desorption (SAVD), regenerative silver oxide chemisorption, and electrochemical carbon dioxide concentration (EDC). Membrane-based carbon dioxide removal and humidity control, catalytic reduction of carbon dioxide, and catalytic oxidation of trace contaminants were also investigated.

  3. Tay-Sachs disease in Brazilian patients: prevalence of the IVS7+1g>c mutation.

    PubMed

    Rozenberg, R; Martins, A M; Micheletti, C; Mustacchi, Z; Pereira, L V

    2004-01-01

    Seven Brazilian Tay-Sachs disease cases were screened for the most frequent causative mutations. They all presented at least one copy of the IVS7+1g>c mutation. Three patients were homozygotes, three were compound heterozygotes, and in one case only the mother was tested and shown to carry the IVS7+1g>c mutation. In the second allele the compound heterozygotes presented: R178H (the DN allele), InsTATC1278 and an unidentified mutation. The IVS7+1g>c mutation has already been described in three Portuguese patients. In this study, all families were unaware of any Portuguese ancestry. Since Brazil was a Portuguese colony, the mutation most probably came from ancient common ancestry. The initial molecular analysis of Tay-Sachs disease patients in Brazil indicated a prevalence of the IVS7+1g>c mutation, possibly as a result of genetic drift.

  4. Turbulence Modeling Validation, Testing, and Development

    NASA Technical Reports Server (NTRS)

    Bardina, J. E.; Huang, P. G.; Coakley, T. J.

    1997-01-01

    The primary objective of this work is to provide accurate numerical solutions for selected flow fields and to compare and evaluate the performance of selected turbulence models with experimental results. Four popular turbulence models have been tested and validated against experimental data often turbulent flows. The models are: (1) the two-equation k-epsilon model of Wilcox, (2) the two-equation k-epsilon model of Launder and Sharma, (3) the two-equation k-omega/k-epsilon SST model of Menter, and (4) the one-equation model of Spalart and Allmaras. The flows investigated are five free shear flows consisting of a mixing layer, a round jet, a plane jet, a plane wake, and a compressible mixing layer; and five boundary layer flows consisting of an incompressible flat plate, a Mach 5 adiabatic flat plate, a separated boundary layer, an axisymmetric shock-wave/boundary layer interaction, and an RAE 2822 transonic airfoil. The experimental data for these flows are well established and have been extensively used in model developments. The results are shown in the following four sections: Part A describes the equations of motion and boundary conditions; Part B describes the model equations, constants, parameters, boundary conditions, and numerical implementation; and Parts C and D describe the experimental data and the performance of the models in the free-shear flows and the boundary layer flows, respectively.

  5. Testing mechanistic models of growth in insects.

    PubMed

    Maino, James L; Kearney, Michael R

    2015-11-22

    Insects are typified by their small size, large numbers, impressive reproductive output and rapid growth. However, insect growth is not simply rapid; rather, insects follow a qualitatively distinct trajectory to many other animals. Here we present a mechanistic growth model for insects and show that increasing specific assimilation during the growth phase can explain the near-exponential growth trajectory of insects. The presented model is tested against growth data on 50 insects, and compared against other mechanistic growth models. Unlike the other mechanistic models, our growth model predicts energy reserves per biomass to increase with age, which implies a higher production efficiency and energy density of biomass in later instars. These predictions are tested against data compiled from the literature whereby it is confirmed that insects increase their production efficiency (by 24 percentage points) and energy density (by 4 J mg(-1)) between hatching and the attainment of full size. The model suggests that insects achieve greater production efficiencies and enhanced growth rates by increasing specific assimilation and increasing energy reserves per biomass, which are less costly to maintain than structural biomass. Our findings illustrate how the explanatory and predictive power of mechanistic growth models comes from their grounding in underlying biological processes.

  6. Testing mechanistic models of growth in insects

    PubMed Central

    Maino, James L.; Kearney, Michael R.

    2015-01-01

    Insects are typified by their small size, large numbers, impressive reproductive output and rapid growth. However, insect growth is not simply rapid; rather, insects follow a qualitatively distinct trajectory to many other animals. Here we present a mechanistic growth model for insects and show that increasing specific assimilation during the growth phase can explain the near-exponential growth trajectory of insects. The presented model is tested against growth data on 50 insects, and compared against other mechanistic growth models. Unlike the other mechanistic models, our growth model predicts energy reserves per biomass to increase with age, which implies a higher production efficiency and energy density of biomass in later instars. These predictions are tested against data compiled from the literature whereby it is confirmed that insects increase their production efficiency (by 24 percentage points) and energy density (by 4 J mg−1) between hatching and the attainment of full size. The model suggests that insects achieve greater production efficiencies and enhanced growth rates by increasing specific assimilation and increasing energy reserves per biomass, which are less costly to maintain than structural biomass. Our findings illustrate how the explanatory and predictive power of mechanistic growth models comes from their grounding in underlying biological processes. PMID:26609084

  7. Application of a nonlinear slug test model

    USGS Publications Warehouse

    McElwee, C.D.

    2001-01-01

    Knowledge of the hydraulic conductivity distribution is of utmost importance in understanding the dynamics of an aquifer and in planning the consequences of any action taken upon that aquifer. Slug tests have been used extensively to measure hydraulic conductivity in the last 50 years since Hvorslev's (1951) work. A general nonlinear model based on the Navier-Stokes equation, nonlinear frictional loss, non-Darcian flow, acceleration effects, radius changes in the wellbore, and a Hvorslev model for the aquifer has been implemented in this work. The nonlinear model has three parameters: ??, which is related primarily to radius changes in the water column; A, which is related to the nonlinear head losses; and K, the hydraulic conductivity. An additional parameter has been added representing the initial velocity of the water column at slug initiation and is incorporated into an analytical solution to generate the first time step before a sequential numerical solution generates the remainder of the time solution. Corrections are made to the model output for acceleration before it is compared to the experimental data. Sensitivity analysis and least squares fitting are used to estimate the aquifer parameters and produce some diagnostic results, which indicate the accuracy of the fit. Finally, an example of field data has been presented to illustrate the application of the model to data sets that exhibit nonlinear behavior. Multiple slug tests should be taken at a given location to test for nonlinear effects and to determine repeatability.

  8. CIIA prevents SOD1(G93A)-induced cytotoxicity by blocking ASK1-mediated signaling

    PubMed Central

    Lee, Jae Keun; Hwang, Sang Gil; Shin, Jin Hee; Shim, Jaekyung; Choi, Eui-Ju

    2014-01-01

    Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease with higher selectivity in degeneration of motor neurons. However, the molecular mechanism by which the ALS-linked mutants of human superoxide dismutase 1 (SOD1) gene induce neurotoxicity remains obscure yet. Here, we show that depletion of CIIA expression by RNA interference (RNAi) promoted cytotoxicity caused by ALS-linked G93A mutant of the SOD1 gene. The RNAi-mediated knockdown of CIIA also enhanced the SOD1(G93A)-induced interaction between ASK1 and TRAF2 as well as ASK1 activity. Furthermore, endogenous silencing of CIIA by RNAi augmented the effects of SOD1(G93A) on reduction of mitochondria membrane potential (Δψm), release of cytochrome c into the cytoplasm, and caspase activation. Together, our results suggest that CIIA negatively modulates ASK1-mediated cytotoxic signaling processes in a SOD1(G93A)-expressing cellular model of ALS. PMID:25018698

  9. Prospective Tests on Biological Models of Acupuncture

    PubMed Central

    2009-01-01

    The biological effects of acupuncture include the regulation of a variety of neurohumoral factors and growth control factors. In science, models or hypotheses with confirmed predictions are considered more convincing than models solely based on retrospective explanations. Literature review showed that two biological models of acupuncture have been prospectively tested with independently confirmed predictions: The neurophysiology model on the long-term effects of acupuncture emphasizes the trophic and anti-inflammatory effects of acupuncture. Its prediction on the peripheral effect of endorphin in acupuncture has been confirmed. The growth control model encompasses the neurophysiology model and suggests that a macroscopic growth control system originates from a network of organizers in embryogenesis. The activity of the growth control system is important in the formation, maintenance and regulation of all the physiological systems. Several phenomena of acupuncture such as the distribution of auricular acupuncture points, the long-term effects of acupuncture and the effect of multimodal non-specific stimulation at acupuncture points are consistent with the growth control model. The following predictions of the growth control model have been independently confirmed by research results in both acupuncture and conventional biomedical sciences: (i) Acupuncture has extensive growth control effects. (ii) Singular point and separatrix exist in morphogenesis. (iii) Organizers have high electric conductance, high current density and high density of gap junctions. (iv) A high density of gap junctions is distributed as separatrices or boundaries at body surface after early embryogenesis. (v) Many acupuncture points are located at transition points or boundaries between different body domains or muscles, coinciding with the connective tissue planes. (vi) Some morphogens and organizers continue to function after embryogenesis. Current acupuncture research suggests a convergence

  10. Parametric Testing of Launch Vehicle FDDR Models

    NASA Technical Reports Server (NTRS)

    Schumann, Johann; Bajwa, Anupa; Berg, Peter; Thirumalainambi, Rajkumar

    2011-01-01

    For the safe operation of a complex system like a (manned) launch vehicle, real-time information about the state of the system and potential faults is extremely important. The on-board FDDR (Failure Detection, Diagnostics, and Response) system is a software system to detect and identify failures, provide real-time diagnostics, and to initiate fault recovery and mitigation. The ERIS (Evaluation of Rocket Integrated Subsystems) failure simulation is a unified Matlab/Simulink model of the Ares I Launch Vehicle with modular, hierarchical subsystems and components. With this model, the nominal flight performance characteristics can be studied. Additionally, failures can be injected to see their effects on vehicle state and on vehicle behavior. A comprehensive test and analysis of such a complicated model is virtually impossible. In this paper, we will describe, how parametric testing (PT) can be used to support testing and analysis of the ERIS failure simulation. PT uses a combination of Monte Carlo techniques with n-factor combinatorial exploration to generate a small, yet comprehensive set of parameters for the test runs. For the analysis of the high-dimensional simulation data, we are using multivariate clustering to automatically find structure in this high-dimensional data space. Our tools can generate detailed HTML reports that facilitate the analysis.

  11. Vibration and Temperature Survey Production AH-1G Helicopter

    DTIC Science & Technology

    1974-03-01

    Temperature rise was determined by subtracting the outside air temperature from the component temperature of interest. 26, Solar radiation had a significant...effect on both static and in-flight temperatures. In-flight data were obtained over a range of solar radiation values by recording data at different...tenmperature data presented in table 6 were obtained by averaging the temperature data over the range of solar radiation values tested. Static

  12. EDU liquid acquisition device outflow tests in liquid hydrogen: Experiments and analytical modeling

    NASA Astrophysics Data System (ADS)

    Hartwig, J. W.; Darr, S. R.; Meyerhofer, P.; Garces, R.

    2017-10-01

    This paper presents experiments and modeling of the most recent set of liquid acquisition device (LAD) vertical outflow tests conducted in liquid hydrogen. The Engineering Development Unit (EDU) was a relatively large tank (4.25 m3) used to mimic a storage tank for a cryogenic storage and transfer flight demonstration test. Six 1-g propellant tank outflow tests were conducted with a standard 325 × 2300 rectangular cross-section curved LAD channel conformal to the tank walls over a range of tank pressure (158-221 kPa), ullage temperature (22-39 K), and mass flow rate (0.0103-0.0187 kg/s) per arm. An analytical LAD channel solver, an exact solution to the Navier-Stokes equations, is used to model propellant outflow for the LAD channel. Results shows that the breakdown height of the LAD is dominated by liquid and ullage gas temperatures, with a secondary effect of flow rate. The best performance is always obtained by exposing the channel to cold pressurant gas and low flow rates, consistent with the cryogenic bubble point model. The model tracks the trends in the data and shows that the contribution of flow-through-screen pressure drop is minimized for bottom outflow in 1-g, versus the standard inverted outflow.

  13. Testing the Correlated Random Coefficient Model*

    PubMed Central

    Heckman, James J.; Schmierer, Daniel; Urzua, Sergio

    2010-01-01

    The recent literature on instrumental variables (IV) features models in which agents sort into treatment status on the basis of gains from treatment as well as on baseline-pretreatment levels. Components of the gains known to the agents and acted on by them may not be known by the observing economist. Such models are called correlated random coe cient models. Sorting on unobserved components of gains complicates the interpretation of what IV estimates. This paper examines testable implications of the hypothesis that agents do not sort into treatment based on gains. In it, we develop new tests to gauge the empirical relevance of the correlated random coe cient model to examine whether the additional complications associated with it are required. We examine the power of the proposed tests. We derive a new representation of the variance of the instrumental variable estimator for the correlated random coefficient model. We apply the methods in this paper to the prototypical empirical problem of estimating the return to schooling and nd evidence of sorting into schooling based on unobserved components of gains. PMID:21057649

  14. Inverse hydrochemical models of aqueous extracts tests

    SciTech Connect

    Zheng, L.; Samper, J.; Montenegro, L.

    2008-10-10

    Aqueous extract test is a laboratory technique commonly used to measure the amount of soluble salts of a soil sample after adding a known mass of distilled water. Measured aqueous extract data have to be re-interpreted in order to infer porewater chemical composition of the sample because porewater chemistry changes significantly due to dilution and chemical reactions which take place during extraction. Here we present an inverse hydrochemical model to estimate porewater chemical composition from measured water content, aqueous extract, and mineralogical data. The model accounts for acid-base, redox, aqueous complexation, mineral dissolution/precipitation, gas dissolution/ex-solution, cation exchange and surface complexation reactions, of which are assumed to take place at local equilibrium. It has been solved with INVERSE-CORE{sup 2D} and been tested with bentonite samples taken from FEBEX (Full-scale Engineered Barrier EXperiment) in situ test. The inverse model reproduces most of the measured aqueous data except bicarbonate and provides an effective, flexible and comprehensive method to estimate porewater chemical composition of clays. Main uncertainties are related to kinetic calcite dissolution and variations in CO2(g) pressure.

  15. A Model-Based Process for Translating Test Programs.

    DTIC Science & Technology

    1996-09-13

    first language , converting the extracted test strategy into an asymmetric dependency model, converting the dependency model into a model based test strategy, extracting code segments from the existing test program, translating the extracted code segments into the second language, and merging the model based test strategy and the translated code segments into a new test program in the second

  16. Empirical tests of evolutionary synthesis models

    NASA Astrophysics Data System (ADS)

    Gomes, Jean Michel; Cid Fernandes, R.

    2010-04-01

    Spectral synthesis of stellar populations has proven to be one of the most powerful methods to decompose the different mixtures of stellar contributions in galaxies, and applications of this technique routinely appear in the literature nowadays. Our group, for instance, the SEAGal (Semi Empirical Analysis of Galaxies) collaboration, has derived the star formation history of all galaxies in the SDSS with the starlight code, obtaining various results of astrophysical interest. As any other fossil method, the results rely heavily on high spectral resolution evolutionary synthesis models. To test this model dependence we run starlight on samples of star-forming and passive galaxies from the SDSS using different sets of models. We explore models using “Padova 1994” and modified “Padova” evolutionary tracks with a different receipt for the asymptotic giant branch phase, as well as different stellar libraries (STELIB versus MILES+Granada). We then compare derived properties such as mean age, mean metallicity, extinction, star-formation and chemical histories. Despite a broad brush agreement, systematic differences emerge from this comparison. The different evolutionary tracks used lead to essentially the same results, at least insofar as optical spectra are concerned. Different stellar libraries, on the other hand, have a much bigger impact. The newer models produce quantifiably better fits and eliminate some pathologies (like suspicious combinations of base elements, systematical spectral residuals in some windows, and, sometimes, negative extinction) of fits derived with STELIB-based models, but there are still some caveats. These empirical tests provide useful feedback for model makers.

  17. Ganymede G1 & G2 Encounters - Interior of Ganymede

    NASA Image and Video Library

    1997-12-16

    NASA's Voyager images are used to create a global view of Ganymede. The cut-out reveals the interior structure of this icy moon. This structure consists of four layers based on measurements of Ganymede's gravity field and theoretical analyses using Ganymede's known mass, size and density. Ganymede's surface is rich in water ice and Voyager and Galileo images show features which are evidence of geological and tectonic disruption of the surface in the past. As with the Earth, these geological features reflect forces and processes deep within Ganymede's interior. Based on geochemical and geophysical models, scientists expected Ganymede's interior to either consist of: a) an undifferentiated mixture of rock and ice or b) a differentiated structure with a large lunar sized "core" of rock and possibly iron overlain by a deep layer of warm soft ice capped by a thin cold rigid ice crust. Galileo's measurement of Ganymede's gravity field during its first and second encounters with the huge moon have basically confirmed the differentiated model and allowed scientists to estimate the size of these layers more accurately. In addition the data strongly suggest that a dense metallic core exists at the center of the rock core. This metallic core suggests a greater degree of heating at sometime in Ganymede's past than had been proposed before and may be the source of Ganymede's magnetic field discovered by Galileo's space physics experiments. http://photojournal.jpl.nasa.gov/catalog/PIA00519

  18. Resveratrol improves motoneuron function and extends survival in SOD1(G93A) ALS mice.

    PubMed

    Mancuso, Renzo; del Valle, Jaume; Modol, Laura; Martinez, Anna; Granado-Serrano, Ana B; Ramirez-Núñez, Omar; Pallás, Mercé; Portero-Otin, Manel; Osta, Rosario; Navarro, Xavier

    2014-04-01

    Amyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disease that causes progressive paralysis and death due to degeneration of motoneurons in spinal cord, brainstem and motor cortex. Nowadays, there is no effective therapy and patients die 2-5 years after diagnosis. Resveratrol (trans-3,4',5-trihydroxystilbene) is a natural polyphenol found in grapes, with promising neuroprotective effects since it induces expression and activation of several neuroprotective pathways involving Sirtuin1 and AMPK. The objective of this work was to assess the effect of resveratrol administration on SOD1(G93A) ALS mice. We determined the onset of symptoms by rotarod test and evaluated upper and lower motoneuron function using electrophysiological tests. We assessed the survival of the animals and determined the number of spinal motoneurons. Finally, we further investigated resveratrol mechanism of action by means of western blot and immunohistochemical analysis. Resveratrol treatment from 8 weeks of age significantly delayed disease onset and preserved lower and upper motoneuron function in female and male animals. Moreover, resveratrol significantly extended SOD1(G93A) mice lifespan and promoted survival of spinal motoneurons. Delayed resveratrol administration from 12 weeks of age also improved spinal motoneuron function preservation and survival. Further experiments revealed that resveratrol protective effects were associated with increased expression and activation of Sirtuin 1 and AMPK in the ventral spinal cord. Both mediators promoted normalization of the autophagic flux and, more importantly, increased mitochondrial biogenesis in the SOD1(G93A) spinal cord. Taken together, our findings suggest that resveratrol may represent a promising therapy for ALS.

  19. Tests characterizing bioprocessor hardware for analytical modeling

    NASA Technical Reports Server (NTRS)

    Gustavino, S.; Mccormack, A.

    1992-01-01

    The tests outlined in this paper were used to characterize the hardware components of the Salad Machine, a small NASA-developed bioprocessor. The data from these tests are presented, and the methods by which this data can be integrated into system mathematical models are briefly discussed. The subsystems and physical processes discussed include the lighting system, the air loop (condensing heat exchanger and the blower), heat transfer to the surroundings, and leakage. Through this effort it was learned that in the development of a test protocol, care should be taken to order the tests such that environmental parameters, particularly humidity, require as few large adjustments as possible. Sensor calibration and installation take a substantial amount of time, which should be built into the test schedule. Two properties were particularly hard to quantify: the air flow rate and the energy from the lighting system entering into the growth volume. Flow rate can be measured using the appropriate device for the system configuration and airflow. Lighting system radiation level was measured using three methods. The results of these methods varied substantially, putting off conclusive quantification of this value.

  20. Tests characterizing bioprocessor hardware for analytical modeling

    NASA Technical Reports Server (NTRS)

    Gustavino, S.; Mccormack, A.

    1992-01-01

    The tests outlined in this paper were used to characterize the hardware components of the Salad Machine, a small NASA-developed bioprocessor. The data from these tests are presented, and the methods by which this data can be integrated into system mathematical models are briefly discussed. The subsystems and physical processes discussed include the lighting system, the air loop (condensing heat exchanger and the blower), heat transfer to the surroundings, and leakage. Through this effort it was learned that in the development of a test protocol, care should be taken to order the tests such that environmental parameters, particularly humidity, require as few large adjustments as possible. Sensor calibration and installation take a substantial amount of time, which should be built into the test schedule. Two properties were particularly hard to quantify: the air flow rate and the energy from the lighting system entering into the growth volume. Flow rate can be measured using the appropriate device for the system configuration and airflow. Lighting system radiation level was measured using three methods. The results of these methods varied substantially, putting off conclusive quantification of this value.

  1. 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.

  2. Thermal modelling of Advanced LIGO test masses

    NASA Astrophysics Data System (ADS)

    Wang, H.; Blair, C.; Dovale Álvarez, M.; Brooks, A.; Kasprzack, M. F.; Ramette, J.; Meyers, P. M.; Kaufer, S.; O'Reilly, B.; Mow-Lowry, C. M.; Freise, A.

    2017-06-01

    High-reflectivity fused silica mirrors are at the epicentre of today’s advanced gravitational wave detectors. In these detectors, the mirrors interact with high power laser beams. As a result of finite absorption in the high reflectivity coatings the mirrors suffer from a variety of thermal effects that impact on the detectors’ performance. We propose a model of the Advanced LIGO mirrors that introduces an empirical term to account for the radiative heat transfer between the mirror and its surroundings. The mechanical mode frequency is used as a probe for the overall temperature of the mirror. The thermal transient after power build-up in the optical cavities is used to refine and test the model. The model provides a coating absorption estimate of 1.5-2.0 ppm and estimates that 0.3 to 1.3 ppm of the circulating light is scattered onto the ring heater.

  3. Testing the Model of Oscillating Magnetic Traps

    NASA Astrophysics Data System (ADS)

    Szaforz, Ż.; Tomczak, M.

    2015-01-01

    The aim of this paper is to test the model of oscillating magnetic traps (the OMT model), proposed by Jakimiec and Tomczak ( Solar Phys. 261, 233, 2010). This model describes the process of excitation of quasi-periodic pulsations (QPPs) observed during solar flares. In the OMT model energetic electrons are accelerated within a triangular, cusp-like structure situated between the reconnection point and the top of a flare loop as seen in soft X-rays. We analyzed QPPs in hard X-ray light curves for 23 flares as observed by Yohkoh. Three independent methods were used. We also used hard X-ray images to localize magnetic traps and soft X-ray images to diagnose thermal plasmas inside the traps. We found that the majority of the observed pulsation periods correlates with the diameters of oscillating magnetic traps, as was predicted by the OMT model. We also found that the electron number density of plasma inside the magnetic traps in the time of pulsation disappearance is strongly connected with the pulsation period. We conclude that the observations are consistent with the predictions of the OMT model for the analyzed set of flares.

  4. Statistical tests of simple earthquake cycle models

    NASA Astrophysics Data System (ADS)

    DeVries, Phoebe M. R.; Evans, Eileen L.

    2016-12-01

    A central goal of observing and modeling the earthquake cycle is to forecast when a particular fault may generate an earthquake: a fault late in its earthquake cycle may be more likely to generate an earthquake than a fault early in its earthquake cycle. Models that can explain geodetic observations throughout the entire earthquake cycle may be required to gain a more complete understanding of relevant physics and phenomenology. Previous efforts to develop unified earthquake models for strike-slip faults have largely focused on explaining both preseismic and postseismic geodetic observations available across a few faults in California, Turkey, and Tibet. An alternative approach leverages the global distribution of geodetic and geologic slip rate estimates on strike-slip faults worldwide. Here we use the Kolmogorov-Smirnov test for similarity of distributions to infer, in a statistically rigorous manner, viscoelastic earthquake cycle models that are inconsistent with 15 sets of observations across major strike-slip faults. We reject a large subset of two-layer models incorporating Burgers rheologies at a significance level of α = 0.05 (those with long-term Maxwell viscosities ηM < 4.0 × 1019 Pa s and ηM > 4.6 × 1020 Pa s) but cannot reject models on the basis of transient Kelvin viscosity ηK. Finally, we examine the implications of these results for the predicted earthquake cycle timing of the 15 faults considered and compare these predictions to the geologic and historical record.

  5. Little phenotypic variability in three CF sibs compound heterozygous for the 621 + 1G-->T and the 711 + 1G-->T mutations.

    PubMed

    De Braekeleer, M; Simard, F; Aubin, G

    1997-03-01

    We describe a family in which three sibs are compound heterozygotes for two rather rare CFTR splice-site mutations, the 621 + 1G-->T and the 711 + 1G-->T mutations. Little phenotypic variation was observed between sibs, of whom two are deceased. Their disease is characterized by pancreatic insufficiency, a severe pulmonary involvement and major growth retardation.

  6. Hexokinase I N-terminal based peptide prevents the VDAC1-SOD1 G93A interaction and re-establishes ALS cell viability

    PubMed Central

    Magrì, Andrea; Belfiore, Ramona; Reina, Simona; Tomasello, Marianna Flora; Di Rosa, Maria Carmela; Guarino, Francesca; Leggio, Loredana; De Pinto, Vito; Messina, Angela

    2016-01-01

    Superoxide Dismutase 1 mutants associate with 20–25% of familial Amyotrophic Lateral Sclerosis (ALS) cases, producing toxic aggregates on mitochondria, notably in spinal cord. The Voltage Dependent Anion Channel isoform 1 (VDAC1) in the outer mitochondrial membrane is a docking site for SOD1 G93A mutant in ALS mice and the physiological receptor of Hexokinase I (HK1), which is poorly expressed in mouse spinal cord. Our results demonstrate that HK1 competes with SOD1 G93A for binding VDAC1, suggesting that in ALS spinal cord the available HK1-binding sites could be used by SOD1 mutants for docking mitochondria, producing thus organelle dysfunction. We tested this model by studying the action of a HK1-N-terminal based peptide (NHK1). This NHK1 peptide specifically interacts with VDAC1, inhibits the SOD1 G93A binding to mitochondria and restores the viability of ALS model NSC34 cells. Altogether, our results suggest that NHK1 peptide could be developed as a therapeutic tool in ALS, predicting an effective role also in other proteinopathies. PMID:27721436

  7. Seepage Calibration Model and Seepage Testing Data

    SciTech Connect

    P. Dixon

    2004-02-17

    The purpose of this Model Report is to document the Seepage Calibration Model (SCM). The SCM is developed (1) to establish the conceptual basis for the Seepage Model for Performance Assessment (SMPA), and (2) to derive seepage-relevant, model-related parameters and their distributions for use in the SMPA and seepage abstraction in support of the Total System Performance Assessment for License Application (TSPA-LA). The SCM is intended to be used only within this Model Report for the estimation of seepage-relevant parameters through calibration of the model against seepage-rate data from liquid-release tests performed in several niches along the Exploratory Studies Facility (ESF) Main Drift and in the Cross Drift. The SCM does not predict seepage into waste emplacement drifts under thermal or ambient conditions. Seepage predictions for waste emplacement drifts under ambient conditions will be performed with the SMPA (see upcoming REV 02 of CRWMS M&O 2000 [153314]), which inherits the conceptual basis and model-related parameters from the SCM. Seepage during the thermal period is examined separately in the Thermal Hydrologic (TH) Seepage Model (see BSC 2003 [161530]). The scope of this work is (1) to evaluate seepage rates measured during liquid-release experiments performed in several niches in the Exploratory Studies Facility (ESF) and in the Cross Drift, which was excavated for enhanced characterization of the repository block (ECRB); (2) to evaluate air-permeability data measured in boreholes above the niches and the Cross Drift to obtain the permeability structure for the seepage model; (3) to use inverse modeling to calibrate the SCM and to estimate seepage-relevant, model-related parameters on the drift scale; (4) to estimate the epistemic uncertainty of the derived parameters, based on the goodness-of-fit to the observed data and the sensitivity of calculated seepage with respect to the parameters of interest; (5) to characterize the aleatory uncertainty of

  8. Effort test failure: toward a predictive model.

    PubMed

    Webb, James W; Batchelor, Jennifer; Meares, Susanne; Taylor, Alan; Marsh, Nigel V

    2012-01-01

    Predictors of effort test failure were examined in an archival sample of 555 traumatically brain-injured (TBI) adults. Logistic regression models were used to examine whether compensation-seeking, injury-related, psychological, demographic, and cultural factors predicted effort test failure (ETF). ETF was significantly associated with compensation-seeking (OR = 3.51, 95% CI [1.25, 9.79]), low education (OR:. 83 [.74, . 94]), self-reported mood disorder (OR: 5.53 [3.10, 9.85]), exaggerated displays of behavior (OR: 5.84 [2.15, 15.84]), psychotic illness (OR: 12.86 [3.21, 51.44]), being foreign-born (OR: 5.10 [2.35, 11.06]), having sustained a workplace accident (OR: 4.60 [2.40, 8.81]), and mild traumatic brain injury severity compared with very severe traumatic brain injury severity (OR: 0.37 [0.13, 0.995]). ETF was associated with a broader range of statistical predictors than has previously been identified and the relative importance of psychological and behavioral predictors of ETF was evident in the logistic regression model. Variables that might potentially extend the model of ETF are identified for future research efforts.

  9. Using Noise for Model-Testing

    PubMed Central

    2012-01-01

    Abstract For realistic models in molecular biology, you need to consider the noise in the cellular and intracellular environments. In this article, we present a novel approach for testing the validity of nonlinear models representing a biological system affected by noise. Our approach is based on results by Kushner and Øksendal and uses computational techniques that rely on efficient solvers. By providing analytically upper bounds for the exit probability of solution trajectories of a system from a particular set in the phase space, we can compare measurement data with this prediction and try to invalidate models with certain parameter values or noise properties. Thus, our approach complements the usual methods that are based on deterministic models. It is particularly useful in the field of reverse engineering in systems biology, when one seeks to determine model parameters and noise properties as we show in the Results section, where we applied the approach to examples of increasing complexity and to the Hog1 signalling pathway. PMID:22876788

  10. Correlation of AH-1G airframe flight vibration data with a coupled rotor-fuselage analysis

    NASA Technical Reports Server (NTRS)

    Sangha, K.; Shamie, J.

    1990-01-01

    The formulation and features of the Rotor-Airframe Comprehensive Analysis Program (RACAP) is described. The analysis employs a frequency domain, transfer matrix approach for the blade structural model, a time domain wake or momentum theory aerodynamic model, and impedance matching for rotor-fuselage coupling. The analysis is applied to the AH-1G helicopter, and a correlation study is conducted on fuselage vibration predictions. The purpose of the study is to evaluate the state-of-the-art in helicopter fuselage vibration prediction technology. The fuselage vibration predicted using RACAP are fairly good in the vertical direction and somewhat deficient in the lateral/longitudinal directions. Some of these deficiencies are traced to the fuselage finite element model.

  11. Model-independent tests of cosmic gravity.

    PubMed

    Linder, Eric V

    2011-12-28

    Gravitation governs the expansion and fate of the universe, and the growth of large-scale structure within it, but has not been tested in detail on these cosmic scales. The observed acceleration of the expansion may provide signs of gravitational laws beyond general relativity (GR). Since the form of any such extension is not clear, from either theory or data, we adopt a model-independent approach to parametrizing deviations to the Einstein framework. We explore the phase space dynamics of two key post-GR functions and derive a classification scheme, and an absolute criterion on accuracy necessary for distinguishing classes of gravity models. Future surveys will be able to constrain the post-GR functions' amplitudes and forms to the required precision, and hence reveal new aspects of gravitation.

  12. Spike Decomposition Technique: Modeling and Performance Tests

    NASA Astrophysics Data System (ADS)

    Nita, G. M.; Fleishman, G. D.; Gary, D. E.

    2008-05-01

    We develop an automated technique for fitting the spectral components of solar microwave spike bursts characterized by narrow-band (1-50~MHz) features of 1-10~ms duration, which are thought to be due to Electron-Cyclotron Maser emission. The algorithm is especially useful for periods when the spikes occur in densely packed clusters, where the algorithm is capable of decomposing overlapping spike structures into individual spectral components. To test the performance and applicability limits of this forward fitting algorithm, we perform comprehensive modeling of spike clusters characterized by various typical bandwidths, spike densities, and amplitude distributions. We find that, for a wide range of input parameters, the algorithm is able to recover the characteristic features of the modeled distributions within reasonable confidence intervals. Having model-tested the algorithm comprehensively against spike overlap, broadband spectral background, noise contamination, and possible contamination of cross-channel polarization, we apply the technique to observational data obtained from different instruments in different frequency ranges. Specifically, we studied spike clusters recorded by a Chinese Purple Mountain Observatory (PMO) spectrometer above 4.5 GHz and by Owens Valley Solar Array's FASR Subsystem Testbed instrument above 1 GHz. We study variation of the spike distribution parameters, such as amplitude, bandwidth and related derived physical parameters as a function of frequency and time. We discuss the implications of our results for the choice between competing models of spike generation and underlying physical processes. The method can be further applied to observations from other instruments and to other types of radio spectral fine structures. This work was supported in part by NSF grants AST-0607544 and ATM-0707319 and NASA grant NNG06GJ40G to New Jersey Institute of Technology.

  13. Seepage Calibration Model and Seepage Testing Data

    SciTech Connect

    S. Finsterle

    2004-09-02

    The purpose of this Model Report is to document the Seepage Calibration Model (SCM). The SCM was developed (1) to establish the conceptual basis for the Seepage Model for Performance Assessment (SMPA), and (2) to derive seepage-relevant, model-related parameters and their distributions for use in the SMPA and seepage abstraction in support of the Total System Performance Assessment for License Application (TSPA-LA). This Model Report has been revised in response to a comprehensive, regulatory-focused evaluation performed by the Regulatory Integration Team [''Technical Work Plan for: Regulatory Integration Evaluation of Analysis and Model Reports Supporting the TSPA-LA'' (BSC 2004 [DIRS 169653])]. The SCM is intended to be used only within this Model Report for the estimation of seepage-relevant parameters through calibration of the model against seepage-rate data from liquid-release tests performed in several niches along the Exploratory Studies Facility (ESF) Main Drift and in the Cross-Drift. The SCM does not predict seepage into waste emplacement drifts under thermal or ambient conditions. Seepage predictions for waste emplacement drifts under ambient conditions will be performed with the SMPA [''Seepage Model for PA Including Drift Collapse'' (BSC 2004 [DIRS 167652])], which inherits the conceptual basis and model-related parameters from the SCM. Seepage during the thermal period is examined separately in the Thermal Hydrologic (TH) Seepage Model [see ''Drift-Scale Coupled Processes (DST and TH Seepage) Models'' (BSC 2004 [DIRS 170338])]. The scope of this work is (1) to evaluate seepage rates measured during liquid-release experiments performed in several niches in the Exploratory Studies Facility (ESF) and in the Cross-Drift, which was excavated for enhanced characterization of the repository block (ECRB); (2) to evaluate air-permeability data measured in boreholes above the niches and the Cross-Drift to obtain the permeability structure for the seepage model

  14. Evolution of gait abnormalities in SOD1(G93A) transgenic mice.

    PubMed

    Mancuso, Renzo; Oliván, Sara; Osta, Rosario; Navarro, Xavier

    2011-08-11

    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the loss of upper and lower motoneurons. Clinically, it is manifested by weakness, muscle atrophy and progressive paralysis and ends up with patients' death 2-5 years after diagnosis. Although these symptoms lead in many cases to gait deficits in patients, an exhaustive locomotor profile of animal models mimicking the disease has not been assessed yet. In this work we evaluated the locomotor performance of the SOD1(G93A) mouse model of ALS using computerized treadmill gait analysis. SOD1(G93A) mice presented early (8 weeks of age) gait abnormalities, evidenced by an increase in the time of the propulsion phase of hindlimb stance. The alterations progressed during the disease until a complete disturbance of normal gait. This finding is meaningful to the field because the identification of a significant difference in a functional endpoint as early as 8 weeks might be a step forward resolving the debate about treatment of mice prior to the symptomatic phase in efficacy studies. These results also point out that digitizing analysis of treadmill locomotion may be useful to evaluate whether new therapeutic approaches are improving functional outcome of the animals.

  15. Testing Cosmological Models with Clusters of Galaxies

    NASA Astrophysics Data System (ADS)

    Böhringer, Hans; Schuecker, Peter

    2003-05-01

    Galaxy clusters are ideal probes for the large-scale structure of the Universe and for the tests of cosmological models. We use, REFLEX, the currently largest and best defined cluster X-ray survey to illustrate this application of galaxy cluster studies. Based on this survey of X-ray selected clusters of galaxies we determine statistical properties of the galaxy cluster population, their spatial correlation, and the density fluctuation power spectrum of the cosmic matter distribution on large scales up to about 1 Gpc. Comparing these results with predictions of cosmological models we obtain tight constrains for the matter density parameter of the Universe, consistent with the combined results from observations of the microwave background anisotropies and distant type Ia supernovae. The only difference between the present results and the ``concordance model'' is a low value for the σ8-normalization. Exploring the parameter space of the cosmic matter density and the equation of state parameter of dark energy most favoured by the combined observations of REFLEX clusters and distant type Ia supernovae we find that the conventional cosmological constant model is best consistent with the observational data.

  16. Testing Physical Models of Passive Membrane Permeation

    PubMed Central

    Leung, Siegfried S. F.; Mijalkovic, Jona; Borrelli, Kenneth; Jacobson, Matthew P.

    2012-01-01

    The biophysical basis of passive membrane permeability is well understood, but most methods for predicting membrane permeability in the context of drug design are based on statistical relationships that indirectly capture the key physical aspects. Here, we investigate molecular mechanics-based models of passive membrane permeability and evaluate their performance against different types of experimental data, including parallel artificial membrane permeability assays (PAMPA), cell-based assays, in vivo measurements, and other in silico predictions. The experimental data sets we use in these tests are diverse, including peptidomimetics, congeneric series, and diverse FDA approved drugs. The physical models are not specifically trained for any of these data sets; rather, input parameters are based on standard molecular mechanics force fields, such as partial charges, and an implicit solvent model. A systematic approach is taken to analyze the contribution from each component in the physics-based permeability model. A primary factor in determining rates of passive membrane permeation is the conformation-dependent free energy of desolvating the molecule, and this measure alone provides good agreement with experimental permeability measurements in many cases. Other factors that improve agreement with experimental data include deionization and estimates of entropy losses of the ligand and the membrane, which lead to size-dependence of the permeation rate. PMID:22621168

  17. Can binary stars test solar models?

    NASA Technical Reports Server (NTRS)

    Popper, D. M.; Ulrich, R. K.

    1986-01-01

    The position in the H-R diagram of the approximately solar-mass component of the Hyades eclipsing binary, HD 27130, is compared with the predictions of stellar structure theory. The stellar models are calibrated by matching a model with the solar heavy element composition and age to the solar radius and luminosity. The comparison to the Hyades binary then is a test of the prediction that the initial solar luminosity was only about 0.7 times the present solar luminosity. The agreement is satisfactory, lending a measure of confidence to the solar model employed, provided that the initial helium abundance of the Hyades stars is not greater than that of the sun and is not less by more than about 0.03 in Y. Unless the model is grossly incorrect, the inference of Stromgren, Olsen, and Gustafsson (1982) from the 'Hyades anomaly' in intermediate-band photometry that Y(Hyades) is less than Y(solar) by 0.1 or 0.15 is rejected by the observed properties of HD 27130.

  18. Can binary stars test solar models?

    NASA Technical Reports Server (NTRS)

    Popper, D. M.; Ulrich, R. K.

    1986-01-01

    The position in the H-R diagram of the approximately solar-mass component of the Hyades eclipsing binary, HD 27130, is compared with the predictions of stellar structure theory. The stellar models are calibrated by matching a model with the solar heavy element composition and age to the solar radius and luminosity. The comparison to the Hyades binary then is a test of the prediction that the initial solar luminosity was only about 0.7 times the present solar luminosity. The agreement is satisfactory, lending a measure of confidence to the solar model employed, provided that the initial helium abundance of the Hyades stars is not greater than that of the sun and is not less by more than about 0.03 in Y. Unless the model is grossly incorrect, the inference of Stromgren, Olsen, and Gustafsson (1982) from the 'Hyades anomaly' in intermediate-band photometry that Y(Hyades) is less than Y(solar) by 0.1 or 0.15 is rejected by the observed properties of HD 27130.

  19. Statistical tests of simple earthquake cycle models

    USGS Publications Warehouse

    Devries, Phoebe M. R.; Evans, Eileen

    2016-01-01

    A central goal of observing and modeling the earthquake cycle is to forecast when a particular fault may generate an earthquake: a fault late in its earthquake cycle may be more likely to generate an earthquake than a fault early in its earthquake cycle. Models that can explain geodetic observations throughout the entire earthquake cycle may be required to gain a more complete understanding of relevant physics and phenomenology. Previous efforts to develop unified earthquake models for strike-slip faults have largely focused on explaining both preseismic and postseismic geodetic observations available across a few faults in California, Turkey, and Tibet. An alternative approach leverages the global distribution of geodetic and geologic slip rate estimates on strike-slip faults worldwide. Here we use the Kolmogorov-Smirnov test for similarity of distributions to infer, in a statistically rigorous manner, viscoelastic earthquake cycle models that are inconsistent with 15 sets of observations across major strike-slip faults. We reject a large subset of two-layer models incorporating Burgers rheologies at a significance level of α = 0.05 (those with long-term Maxwell viscosities ηM <~ 4.0 × 1019 Pa s and ηM >~ 4.6 × 1020 Pa s) but cannot reject models on the basis of transient Kelvin viscosity ηK. Finally, we examine the implications of these results for the predicted earthquake cycle timing of the 15 faults considered and compare these predictions to the geologic and historical record.

  20. A test of the Hapke photometric model

    NASA Astrophysics Data System (ADS)

    Shepard, Michael K.; Helfenstein, Paul

    2007-03-01

    We conducted a test of the Hapke (1981, 1984, 1986, 2002) photometric model to determine what physical parameters could be confidently linked to a surface's photometric behavior. The first author selected and measured the bidirectional reflectance distribution functions of 14 different samples in up to three different wavelengths using the Bloomsburg University Goniometer Laboratory. A total of 29 data files were obtained, each file containing more than 700 measurements from different viewing geometries; phase angles varied from 3° to 130°. The 29 files were initially sent ``in-the-blind'' to the second author, who was charged with inverting the data files and extracting best fit model parameters. Our baseline model used the most recent Hapke (2002) formulation with a two-term Henyey-Greenstein particle phase function and shadow-hiding backscatter opposition effect (SHOE) model. We also inverted the data with three other variations that included three-term Henyey-Greenstein phase functions and both SHOE and the coherent backscatter opposition effect (CBOE) models. Our results were compared with the known physical properties of our samples. We found no compelling evidence that individual photometric parameters could be uniquely interpreted to reveal the physical state of our samples, either in an absolute or relative sense. Rather, combinations of physical properties such as albedo, roughness, and porosity were convolved within each retrieved photometric parameter. On the basis of our empirical evidence, we speculate that the fault lies with the inability of radiative transfer models to adequately account for discrete media and the effects of porosity, and its deficient assumption that individual particles are the primary scattering units.

  1. Modeling of airplane performance from flight-test results and validation with an F-104G airplane

    NASA Technical Reports Server (NTRS)

    Marshall, R. T.; Schweikhard, W. G.

    1973-01-01

    A technique of defining an accurate performance model of an airplane from limited flight-test data and predicted aerodynamic and propulsion system characteristics is developed. With the modeling technique, flight-test data from level accelerations are used to define a 1g performance model for the entire flight envelope of an F-104G airplane. The performance model is defined in terms of the thrust and drag of the airplane and can be varied with changes in ambient temperature or airplane weight. The model predicts the performance of the airplane within 5 percent of the measured flight-test data. The modeling technique could substantially reduce the time required for performance flight testing and produce a clear definition of the thrust and drag characteristics of an airplane.

  2. The C. elegans model in toxicity testing

    PubMed Central

    2016-01-01

    Abstract Caenorhabditis elegans is a small nematode that can be maintained at low cost and handled using standard in vitro techniques. Unlike toxicity testing using cell cultures, C. elegans toxicity assays provide data from a whole animal with intact and metabolically active digestive, reproductive, endocrine, sensory and neuromuscular systems. Toxicity ranking screens in C. elegans have repeatedly been shown to be as predictive of rat LD50 ranking as mouse LD50 ranking. Additionally, many instances of conservation of mode of toxic action have been noted between C. elegans and mammals. These consistent correlations make the case for inclusion of C. elegans assays in early safety testing and as one component in tiered or integrated toxicity testing strategies, but do not indicate that nematodes alone can replace data from mammals for hazard evaluation. As with cell cultures, good C. elegans culture practice (GCeCP) is essential for reliable results. This article reviews C. elegans use in various toxicity assays, the C. elegans model's strengths and limitations for use in predictive toxicology, and GCeCP. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Journal of Applied Toxicology published by John Wiley & Sons Ltd. PMID:27443595

  3. Test Cases for Reentry Survivability Modeling

    NASA Astrophysics Data System (ADS)

    Ailor, W.; Hallman, W.; Steckel, G.; Weaver, M.

    2012-01-01

    One approved approach for minimizing the long-term hazards posed by space debris is to reenter space hardware into the atmosphere at end-of-mission or to place hardware in an orbit with a relatively short lifetime. Selection of a short lifetime orbit vice a deorbited reentry into a safe area depends on predictions of the hazards posed by random reentry of the object. If the object is left in orbit, what is the casualty expectation associated with its eventual reentry? Clearly, having high confidence in reentry hazard prediction tools is important to this decision-making process and the final choice can have significant mission and cost impacts. This paper describes a set of test cases that can be used to validate reentry hazard models. The test cases were assembled from reentry cases where "known" and tracked objects reentered the atmosphere and debris from the reentries was subsequently found on the ground and was analyzed. The test cases include best estimates of the state, mass properties, and physical description of each object prior to reentry, the wind profile through which the debris fell (for one case), and the impact location and physical description of each surviving object. The report also summarizes results of metallurgical analyses conducted on surviving debris, which places limits on the maximum temperatures reached during reentry. Details on a specific reentry are included as an example.

  4. Applying Model Checking to Generate Model-Based Integration Tests from Choreography Models

    NASA Astrophysics Data System (ADS)

    Wieczorek, Sebastian; Kozyura, Vitaly; Roth, Andreas; Leuschel, Michael; Bendisposto, Jens; Plagge, Daniel; Schieferdecker, Ina

    Choreography models describe the communication protocols between services. Testing of service choreographies is an important task for the quality assurance of service-based systems as used e.g. in the context of service-oriented architectures (SOA). The formal modeling of service choreographies enables a model-based integration testing (MBIT) approach. We present MBIT methods for our service choreography modeling approach called Message Choreography Models (MCM). For the model-based testing of service choreographies, MCMs are translated into Event-B models and used as input for our test generator which uses the model checker ProB.

  5. 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.

  6. Thermal Model of the Promoted Combustion Test

    NASA Technical Reports Server (NTRS)

    Jones, Peter D.

    1996-01-01

    Flammability of metals in high pressure, pure oxygen environments, such as rocket engine turbopumps, is commonly evaluated using the Promoted Combustion Test (PCT). The PCT emphasizes the ability of an ignited material to sustain combustion, as opposed to evaluating the sample's propensity to ignite in the first place. A common arrangement is a rod of the sample material hanging in a chamber in which a high pressure, pure oxygen environment is maintained. An igniter of some energetically combusting material is fixed to the bottom of the rod and fired. This initiates combustion, and the sample burns and melts at its bottom tip. A ball of molten material forms, and this ball detaches when it grows too large to be supported by surface tension with the rod. In materials which do not sustain combustion, the combustion then extinguishes. In materials which do sustain combustion, combustion re-initiates from molten residue left on the bottom of the rod, and the melt ball burns and grows until it detaches again. The purpose of this work is development of a PCT thermal simulation model, detailing phase change, melt detachment, and the several heat transfer modes. Combustion is modeled by a summary rate equation, whose parameters are identified by comparison to PCT results. The sensitivity of PCT results to various physical and geometrical parameters is evaluated. The identified combustion parameters may be used in design of new PCT arrangements, as might be used for flammability assessment in flow-dominated environments. The Haynes 214 nickel-based superalloy, whose PCT results are applied here, burns heterogeneously (fuel and oxidizer are of different phases; combustion takes place on the fuel surface). Heterogeneous combustion is not well understood. (In homogeneous combustion, the metal vaporizes, and combustion takes place in an analytically treatable cloud above the surface). Thermal modeling in heterogeneous combustion settings provides a means for linking test

  7. Preservation of neuromuscular function in symptomatic SOD1-G93A mice by peripheral infusion of methylene blue.

    PubMed

    Talbot, Janet D; Barrett, John N; Nonner, Doris; Zhang, Zhongsheng; Wicomb, Kyle; Barrett, Ellen F

    2016-11-01

    In mutant superoxide dismutase 1 (SOD1) mouse models of familial amyotrophic lateral sclerosis (fALS) some of the earliest signs of morphological and functional damage occur in the motor nerve terminals that innervate fast limb muscles. This study tested whether localized peripheral application of a protective drug could effectively preserve neuromuscular junctions in late-stage disease. Methylene blue (MB), which has mitochondria-protective properties, was infused via an osmotic pump into the anterior muscle compartment of one hind limb of late pre- symptomatic SOD1-G93A mice for ≥3weeks. When mice reached end-stage disease, peak twitch and tetanic contractions evoked by stimulation of the muscle nerve were measured in two anterior compartment muscles (tibialis anterior [TA] and extensor digitorum longus [EDL], both predominantly fast muscles). With 400μM MB in the infusion reservoir, muscles on the MB-infused side exhibited on average a ~100% increase in nerve-evoked contractile force compared to muscles on the contralateral non-infused side (p<0.01 for both twitch and tetanus in EDL and TA). Pairwise comparisons of endplate innervation also revealed a beneficial effect of MB infusion, with an average of 65% of endplates innervated in infused EDL, compared to only 35% on the non-infused side (p<0.01). Results suggested that MB's protective effects required an extracellular [MB] of ~1μM, were initiated peripherally (no evidence of retrograde transport into the spinal cord), and involved MB's reduced form. Thus peripherally-initiated actions of MB can help preserve neuromuscular structure and function in SOD1-G93A mice, even at late stages of disease. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Testing Solar Flare Models with BATSE

    NASA Technical Reports Server (NTRS)

    Zarro, Dominic M.

    1995-01-01

    We propose to use high-sensitivity Burst and Transient Source Experiment (BATSE) hard X-ray observations to test the thick-target and electric field acceleration models of solar flares. We will compare the predictions made by these models with hard X-ray spectral observations obtained with BATSE and simultaneous soft X-ray Ca XIX emission observed with the Yohkoh Bragg Crystal Spectrometer (BCS). The increased sensitivities of the BATSE and BCS (relative to previous detectors) permits a renewed study of the relationship between heating and dynamical motions during the crucial rise phase of flares. With these observations, we will: (1) investigate the ability of the thick-target model to explain the temporal evolution of hard X-ray emission relative to the soft X-ray blueshift during the earliest stages of the impulsive phase; and (2) search for evidence of electric-field acceleration as implied by temporal correlations between hard X-ray spectral breaks and the Ca XIX blueshift. The proposed study will utilize hard X-ray lightcurve and spectral measurements in the 10-100 keV energy range obtained with the BATSE Large Area Detectors (LAD). The DISCLA and CONT data will be the primary data products used in this analysis.

  9. C-kit is important for SOD1(G93A) mouse survival independent of mast cells.

    PubMed

    Staats, K A; Schönefeldt, S; Van Helleputte, L; Van Rillaer, M; Lampi, Y; Dooley, J; Van Den Bosch, L; Liston, A

    2015-08-20

    Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disease leading to progressive and lethal paralysis. The disease process is multi-factorial and is characterized by selective motor neuron degeneration. Previous work demonstrated that the local concentration of various growth factors can influence motor neuron survival and disease progression. A potential role for c-kit, a growth factor receptor present in the spinal cord, in ALS is unknown. To dissect the role of c-kit in ALS we interbred SOD1(G93A) mice with kit(w-sh/w-sh) mice, which have a 70% decrease in c-kit expression in the spinal cord. kit(w-sh/w-sh) SOD1(G93A) mice have a reduced survival compared to SOD1(G93A) mice, while the amount of motor neurons at end stage is similar. By means of grip strength and nerve conductance analysis we show that kit(w-sh/w-sh) mice have diminished strength and slightly impaired compound muscle action potential latency, although the number of neurons is similar across genotypes. Decreasing kit gene expression in SOD1(G93A) mice is detrimental and our results imply that this effect is independent of mast cells, as tested by ketotifen administration. To conclude, our data expand on the protective role of growth factors in ALS, as decreasing c-kit by approximately 70% is detrimental in SOD1(G93A) mice.

  10. Modeling and testing of ethernet transformers

    NASA Astrophysics Data System (ADS)

    Bowen, David

    2011-12-01

    Twisted-pair Ethernet is now the standard home and office last-mile network technology. For decades, the IEEE standard that defines Ethernet has required electrical isolation between the twisted pair cable and the Ethernet device. So, for decades, every Ethernet interface has used magnetic core Ethernet transformers to isolate Ethernet devices and keep users safe in the event of a potentially dangerous fault on the network media. The current state-of-the-art Ethernet transformers are miniature (<5mm diameter) ferrite-core toroids wrapped with approximately 10 to 30 turns of wire. As small as current Ethernet transformers are, they still limit further Ethernet device miniaturization and require a separate bulky package or jack housing. New coupler designs must be explored which are capable of exceptional miniaturization or on-chip fabrication. This dissertation thoroughly explores the performance of the current commercial Ethernet transformers to both increase understanding of the device's behavior and outline performance parameters for replacement devices. Lumped element and distributed circuit models are derived; testing schemes are developed and used to extract model parameters from commercial Ethernet devices. Transfer relation measurements of the commercial Ethernet transformers are compared against the model's behavior and it is found that the tuned, distributed models produce the best transfer relation match to the measured data. Process descriptions and testing results on fabricated thin-film dielectric-core toroid transformers are presented. The best results were found for a 32-turn transformer loaded with 100Ω, the impedance of twisted pair cable. This transformer gave a flat response from about 10MHz to 40MHz with a height of approximately 0.45. For the fabricated transformer structures, theoretical methods to determine resistance, capacitance and inductance are presented. A special analytical and numerical analysis of the fabricated transformer

  11. Testing Planet Formation Models with Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Ford, E. B.

    The first discoveries of extrasolar planets demonstrated that nature produces a much greater diversity of planetary systems than astronomers had anticipated. In an attempt to explain these surprises, theorists have proposed numerous generalizations to the classical model of planet formation. Recently, researchers have begun testing some of these theories by comparing the predicted distributions of planet periods, eccentricities, and masses to those of the observed population of extrasolar planets. Such comparisons are becoming increasingly powerful thanks to the increasing number of known planets, improving measurement precision, increasing temporal baselines, and improving capability to control for detection biases. Here, we discuss some of the orbital properties of the extrasolar planet population based on a systematic analysis of radial velocity planets and discuss implications for the formation and evolution of planetary systems.

  12. Computerized Classification Testing with the Rasch Model

    ERIC Educational Resources Information Center

    Eggen, Theo J. H. M.

    2011-01-01

    If classification in a limited number of categories is the purpose of testing, computerized adaptive tests (CATs) with algorithms based on sequential statistical testing perform better than estimation-based CATs (e.g., Eggen & Straetmans, 2000). In these computerized classification tests (CCTs), the Sequential Probability Ratio Test (SPRT) (Wald,…

  13. Applicable Adaptive Testing Models for School Teachers.

    ERIC Educational Resources Information Center

    Wang, Albert Chang-hwa; Chuang, Chi-lin

    2002-01-01

    Describes a study conducted in Taipei (Taiwan) that investigated the attitudinal effects of SPRT (Sequential Probability Ratio Test) adaptive testing environment on junior high school students. Discusses test anxiety; student preferences; test adaptability; acceptance of test results; number of items answered; and computer experience. (Author/LRW)

  14. Computerized Classification Testing with the Rasch Model

    ERIC Educational Resources Information Center

    Eggen, Theo J. H. M.

    2011-01-01

    If classification in a limited number of categories is the purpose of testing, computerized adaptive tests (CATs) with algorithms based on sequential statistical testing perform better than estimation-based CATs (e.g., Eggen & Straetmans, 2000). In these computerized classification tests (CCTs), the Sequential Probability Ratio Test (SPRT) (Wald,…

  15. 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.

  16. Two Bayesian tests of the GLOMOsys Model.

    PubMed

    Field, Sarahanne M; Wagenmakers, Eric-Jan; Newell, Ben R; Zeelenberg, René; van Ravenzwaaij, Don

    2016-12-01

    Priming is arguably one of the key phenomena in contemporary social psychology. Recent retractions and failed replication attempts have led to a division in the field between proponents and skeptics and have reinforced the importance of confirming certain priming effects through replication. In this study, we describe the results of 2 preregistered replication attempts of 1 experiment by Förster and Denzler (2012). In both experiments, participants first processed letters either globally or locally, then were tested using a typicality rating task. Bayes factor hypothesis tests were conducted for both experiments: Experiment 1 (N = 100) yielded an indecisive Bayes factor of 1.38, indicating that the in-lab data are 1.38 times more likely to have occurred under the null hypothesis than under the alternative. Experiment 2 (N = 908) yielded a Bayes factor of 10.84, indicating strong support for the null hypothesis that global priming does not affect participants' mean typicality ratings. The failure to replicate this priming effect challenges existing support for the GLOMO(sys) model. (PsycINFO Database Record

  17. Pressure Distribution over Thick Airfoils - Model Tests

    NASA Technical Reports Server (NTRS)

    Norton, F H; Bacon, D L

    1923-01-01

    This investigation was undertaken to study the distribution of loading over thick wings of various types. The unloading on the wing was determined by taking the pressure at a number of holes on both the upper and lower surfaces of a model wing in the wind tunnel. The results from these tests show, first, that the distribution of pressure over a thick wing of uniform section is very little different from that over a thin wing; second, that wings tapering either in chord or thickness have the lateral center of pressure, as would be expected, slightly nearer the center of the wings; and, third, that wings tapering in plan form and with a section everywhere proportional to the center section may be considered to have a loading at any point which is proportional to the chord when compared to a wing with a similar constant section. These tests confirm the belief that wings tapering both in thickness and plan form are of considerable structural value because the lateral center of pressure is thereby moved toward the center of the span.

  18. Testing computational toxicology models with phytochemicals.

    PubMed

    Valerio, Luis G; Arvidson, Kirk B; Busta, Emily; Minnier, Barbara L; Kruhlak, Naomi L; Benz, R Daniel

    2010-02-01

    Computational toxicology employing quantitative structure-activity relationship (QSAR) modeling is an evidence-based predictive method being evaluated by regulatory agencies for risk assessment and scientific decision support for toxicological endpoints of interest such as rodent carcinogenicity. Computational toxicology is being tested for its usefulness to support the safety assessment of drug-related substances (e.g. active pharmaceutical ingredients, metabolites, impurities), indirect food additives, and other applied uses of value for protecting public health including safety assessment of environmental chemicals. The specific use of QSAR as a chemoinformatic tool for estimating the rodent carcinogenic potential of phytochemicals present in botanicals, herbs, and natural dietary sources is investigated here by an external validation study, which is the most stringent scientific method of measuring predictive performance. The external validation statistics for predicting rodent carcinogenicity of 43 phytochemicals, using two computational software programs evaluated at the FDA, are discussed. One software program showed very good performance for predicting non-carcinogens (high specificity), but both exhibited poor performance in predicting carcinogens (sensitivity), which is consistent with the design of the models. When predictions were considered in combination with each other rather than based on any one software, the performance for sensitivity was enhanced, However, Chi-square values indicated that the overall predictive performance decreases when using the two computational programs with this particular data set. This study suggests that complementary multiple computational toxicology software need to be carefully selected to improve global QSAR predictions for this complex toxicological endpoint.

  19. Menarche, sexual practices, and pregnancy: model testing.

    PubMed

    Talashek, M L; Montgomery, A C; Moran, C; Paskiewicz, L; Jiang, Y

    2000-03-01

    Rates of adolescent pregnancy and childbearing, while in slight decline in the United States since 1992, remain high enough to warrant significant national concern. Birth rates, however, remain particularly high for minority adolescents. One hundred fifty-two records of African American and Latina adolescents receiving prenatal care from nurse midwives at an inner city university clinic were reviewed to partially test a developmental maturity model of pregnancy using logistic regression. The relationships between age at menarche to sexual practices and age at first pregnancy were examined. Mean age of the sample was 16.5 years, mean age at menarche was 12.2 years, at first coitus was 14.6 years, and at first pregnancy was 15.6 years. Thirty percent of the girls were experiencing second pregnancies. Birth control use by the adolescents was inconsistent, with only 20 percent using birth control at first coitus. Multiple regression analyses produced a model explaining 50 percent of the variance in age at first pregnancy. The predictor variables in the model were age at first coitus, age at menarche, race/ethnicity, and use of birth control at first coitus. Further analyses indicate that for childbearing adolescents, age at first coitus is a classic intervening variable between age at menarche and age at first pregnancy. Early physiologic maturers appear to lack the psychological and cognitive maturity required to cope with their emerging sexuality resulting in early unprotected coitus and pregnancy. Findings provide guidance to healthcare providers for the development of interventions to prevent unplanned pregnancies.

  20. Association between cyclin D1 (CCND1) G870A polymorphism and gastric cancer risk: a meta-analysis

    PubMed Central

    Zhang, Yafei; Zeng, Xianling; Lu, Hongwei; Ji, Hong; Zhao, Enfa; Li, Yiming

    2016-01-01

    Published data on the association between cyclin D1 (CCND1) G870A polymorphism and gastric cancer (GC) risk are inconclusive. Thus, we conducted a meta-analysis to evaluate the relationship between CCND1 G870A polymorphism and GC risk. We searched PubMed, EMBASE, Web of science and the Cochrane Library up to June 12, 2015 for relevant studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to estimate the strength of associations. Nine studies published from 2003 to 2014, with a total of 1813 cases and 2173 controls, were included in this meta-analysis. The pooled results showed that there was no association between CCND1 G870A polymorphism and GC risk in any genetic model. The subgroup analysis stratified by ethnicity showed an increased breast cancer risk in Caucasian based on heterozygote comparison (GA vs. GG: OR=1.49, 95% CI=1.06-2.10, P=0.02). We found the same association in population based (PB) stratified analyses by Source of controls (AA vs. GG: OR=1.39, 95% CI=1.01-1.93, 0.05). When stratifying by the type, Sex and H. pylori infection in dominant model, Interestingly, we found the opposite result in Male (AA + GA vs. GG: OR=0.5, 95% CI=0.33-0.76, P=0.001), there were no association between CCND1 G870A polymorphism and GC risk in any other subgroup. This meta-analysis suggests that CCND1 G870A polymorphism is a risk factor for susceptibility to GC in Caucasians and in general populations. While, CCND1 G870A polymorphism plays a possible protective effect in GC in Male. Further large scale multicenter epidemiological studies are warranted to confirm this finding. PMID:27623072

  1. Initial test results using the GEOS-3 engineering model altimeter

    NASA Technical Reports Server (NTRS)

    Hayne, G. S.; Clary, J. B.

    1977-01-01

    Data from a series of experimental tests run on the engineering model of the GEOS 3 radar altimeter using the Test and Measurement System (TAMS) designed for preflight testing of the radar altimeter are presented. These tests were conducted as a means of preparing and checking out a detailed test procedure to be used in running similar tests on the GEOS 3 protoflight model altimeter systems. The test procedures and results are also included.

  2. Analysis of CFTR transcripts in nasal epithelial cells and lymphoblasts of a cystic fibrosis patient with 621 + 1G-->T and 711 + 1G-->T mutations.

    PubMed

    Zielenski, J; Bozon, D; Markiewicz, D; Aubin, G; Simard, F; Rommens, J M; Tsui, L C

    1993-06-01

    We have analyzed the CFTR mRNA populations in a cystic fibrosis patient heterozygous for the 621 + 1G-->T and 711 + 1G-->T mutations. Total RNA isolated from the nasal epithelial cells and Epstein-Barr virus-transformed lymphoblasts derived from this patient was reversely transcribed and a region extending from exon 3 to exon 7 of the gene was amplified by the polymerase chain reaction and analyzed. Three abnormal products were identified, suggesting the presence of three aberrant transcripts, and their profiles were identical in both cell types. Two of the products were found to be missing either exon 4 or exon 5 as anticipated from the transcripts from the 621 + 1G-->T or 711 + 1G-->T alleles, respectively. The third product was apparently derived from an alternatively spliced mRNA species in the absence of the nominal splice site (in 621 + 1G-->T) through the use of a cryptic splice donor sequence (TT528/GTGAGG) within exon 4. Although reading frames appeared to be preserved in all three putative transcripts, significant portions of the presumed first and second transmembrane spans as well as the immediately following cytoplasmic domain would be deleted from the mutant CFTR polypeptides, if made. These observations are consistent with a loss of CFTR function in this cystic fibrosis patient.

  3. Time-course and characterization of orolingual motor deficits in B6SJL-Tg(SOD1-G93A)1Gur/J mice.

    PubMed

    Smittkamp, S E; Brown, J W; Stanford, J A

    2008-01-24

    Amyotrophic lateral sclerosis (ALS) is a progressive degenerative disease affecting upper and lower motor neurons. Symptom onset may occur in the muscles of the limbs (spinal onset) or those of the head and neck (bulbar onset). Bulbar involvement is particularly important in ALS as it is associated with increased morbidity and mortality. The purpose of this study was to characterize bulbar motor deficits in the B6SJL-Tg(SOD1-G93A)1Gur/J (SOD1-G93A) mouse model of familial ALS. We measured orolingual motor function by placing thirsty mice in a customized operant chamber that allows for measurement of tongue force and lick rhythm as animals lick water from an isometric disc. Testing spanned the pre-symptomatic, symptomatic, and end-stage segments of the disease. Rotarod performance, fore- and hindlimb grip strength, and locomotor activity were also monitored regularly during this period. We found that spinal involvement was apparent first, with both fore- and hindlimb grip strength being affected in SOD1-G93A mice from the onset of testing (64 days of age). Rotarod performance was affected by 71 days of age. Locomotor activity was not affected, even near end-stage. Bulbar involvement appeared much later, with tongue motility being affected by 100 days of age. Tongue force was affected by 115 days of age. To our knowledge, these findings are the first to describe the onset of bulbar versus spinal motor signs and characterize orolingual motor deficits in this preclinical model of ALS.

  4. Effects of spaceflight on rhesus quadrupedal locomotion after return to 1G

    NASA Technical Reports Server (NTRS)

    Recktenwald, M. R.; Hodgson, J. A.; Roy, R. R.; Riazanski, S.; McCall, G. E.; Kozlovskaya, I.; Washburn, D. A.; Fanton, J. W.; Edgerton, V. R.; Rumbaugh, D. M. (Principal Investigator)

    1999-01-01

    Effects of spaceflight on Rhesus quadrupedal locomotion after return to 1G. Locomotor performance, activation patterns of the soleus (Sol), medial gastrocnemius (MG), vastus lateralis (VL), and tibialis anterior (TA) and MG tendon force during quadrupedal stepping were studied in adult Rhesus before and after 14 days of either spaceflight (n = 2) or flight simulation at 1G (n = 3). Flight simulation involved duplication of the spaceflight conditions and experimental protocol in a 1G environment. Postflight, but not postsimulation, electromyographic (EMG) recordings revealed clonus-like activity in all muscles. Compared with preflight, the cycle period and burst durations of the primary extensors (Sol, MG, and VL) tended to decrease postflight. These decreases were associated with shorter steps. The flexor (TA) EMG burst duration postflight was similar to preflight, whereas the burst amplitude was elevated. Consequently, the Sol:TA and MG:TA EMG amplitude ratios were lower following flight, reflecting a "flexor bias." Together, these alterations in mean EMG amplitudes reflect differential adaptations in motor-unit recruitment patterns of flexors and extensors as well as fast and slow motor pools. Shorter cycle period and burst durations persisted throughout the 20-day postflight testing period, whereas mean EMG returned to preflight levels by 17 days postflight. Compared with presimulation, the simulation group showed slight increases in the cycle period and burst durations of all muscles. Mean EMG amplitude decreased in the Sol, increased in the MG and VL, and was unchanged in the TA. Thus adaptations observed postsimulation were different from those observed postflight, indicating that there was a response unique to the microgravity environment, i.e., the modulations in the nervous system controlling locomotion cannot merely be attributed to restriction of movement but appear to be the result of changes in the interpretation of load-related proprioceptive feedback

  5. Effects of spaceflight on rhesus quadrupedal locomotion after return to 1G

    NASA Technical Reports Server (NTRS)

    Recktenwald, M. R.; Hodgson, J. A.; Roy, R. R.; Riazanski, S.; McCall, G. E.; Kozlovskaya, I.; Washburn, D. A.; Fanton, J. W.; Edgerton, V. R.; Rumbaugh, D. M. (Principal Investigator)

    1999-01-01

    Effects of spaceflight on Rhesus quadrupedal locomotion after return to 1G. Locomotor performance, activation patterns of the soleus (Sol), medial gastrocnemius (MG), vastus lateralis (VL), and tibialis anterior (TA) and MG tendon force during quadrupedal stepping were studied in adult Rhesus before and after 14 days of either spaceflight (n = 2) or flight simulation at 1G (n = 3). Flight simulation involved duplication of the spaceflight conditions and experimental protocol in a 1G environment. Postflight, but not postsimulation, electromyographic (EMG) recordings revealed clonus-like activity in all muscles. Compared with preflight, the cycle period and burst durations of the primary extensors (Sol, MG, and VL) tended to decrease postflight. These decreases were associated with shorter steps. The flexor (TA) EMG burst duration postflight was similar to preflight, whereas the burst amplitude was elevated. Consequently, the Sol:TA and MG:TA EMG amplitude ratios were lower following flight, reflecting a "flexor bias." Together, these alterations in mean EMG amplitudes reflect differential adaptations in motor-unit recruitment patterns of flexors and extensors as well as fast and slow motor pools. Shorter cycle period and burst durations persisted throughout the 20-day postflight testing period, whereas mean EMG returned to preflight levels by 17 days postflight. Compared with presimulation, the simulation group showed slight increases in the cycle period and burst durations of all muscles. Mean EMG amplitude decreased in the Sol, increased in the MG and VL, and was unchanged in the TA. Thus adaptations observed postsimulation were different from those observed postflight, indicating that there was a response unique to the microgravity environment, i.e., the modulations in the nervous system controlling locomotion cannot merely be attributed to restriction of movement but appear to be the result of changes in the interpretation of load-related proprioceptive feedback

  6. Model mount system for testing flutter

    NASA Technical Reports Server (NTRS)

    Farmer, M. G. (Inventor)

    1984-01-01

    A wind tunnel model mount system is disclosed for effectively and accurately determining the effects of attack and airstream velocity on a model airfoil or aircraft. The model mount system includes a rigid model attached to a splitter plate which is supported away from the wind tunnel wall several of flexible rods. Conventional instrumentation is employed to effect model rotation through a turntable and to record model flutter data as a function of the angle of attack versus dynamic pressure.

  7. Testing for Local Dependence in Rasch's Multiplicative Gamma Model for Speed Tests

    ERIC Educational Resources Information Center

    Jansen, Margo G. H.

    2007-01-01

    The author considers a latent trait model for the response time on a (set of) pure speed test(s), the multiplicative gamma model (MGM), which is based on the assumption that the test response times are approximately gamma distributed, with known index parameters and scale parameters depending on subject ability and test difficulty parameters. Like…

  8. CCND1 G870A polymorphism and colorectal cancer risk: An updated meta-analysis

    PubMed Central

    XU, XIAO-MING; NI, XIAO-BING; YANG, GONG-LI; LUO, ZHI-GUO; NIU, YU-MING; SHEN, MING

    2016-01-01

    Molecular epidemiological studies have revealed a closer association between cyclin D1 (CCND1) polymorphism and the risk of colorectal cancer; however, the results were inconsistent. The aim of the present meta-analysis was to investigate the association between CCND1 G870A polymorphism and colorectal cancer risk. Online electronic databases (PubMed and Embase) were searched. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the association between CCND1 G870A polymorphism and the risk of colorectal cancer. In addition, heterogeneity, publication bias and sensitivity analysis were performed to guarantee the statistical power. In total, 23 published case-control studies with 6,320 patients and 8,252 controls were selected. Significantly increased risks were observed in four genetic models (A vs. G: OR=1.09, 95% CI=1.00–1.18, I2=54.3%; GA vs. GG: OR=1.13, 95% CI=1.04–1.24, I2=18.2%; AA vs. GG, OR=1.17: 95% CI=1.00–1.38, I2=52.5%; GA+AA vs. GG: OR=1.14, 95% CI=1.05–1.24, I2=33.8%). Similarly, significant associations were also identified in the stratified analysis in the cancer subtype of sporadic colorectal cancer (GA vs. GG: OR=1.21, 95% CI=1.04–1.42, I2=24.1%; GA+AA vs. GG: OR=1.18, 95% CI=1.02–1.37, I2=35.0%), Caucasian population (GA vs. GG, OR=1.14, 95% CI=1.02–1.28, I2=19.8%; GA+AA vs. GG, OR=1.14, 95% CI=1.02–1.27, I2=37.5%) and other subgroups of control design and genotyping type. The present updated meta-analysis suggested that CCND1 G870A may present an increased risk for developing colorectal cancer, particularly in sporadic colorectal cancer and a Caucasian population. PMID:27284448

  9. Modeling Information Accumulation in Psychological Tests Using Item Response Times

    ERIC Educational Resources Information Center

    Ranger, Jochen; Kuhn, Jörg-Tobias

    2015-01-01

    In this article, a latent trait model is proposed for the response times in psychological tests. The latent trait model is based on the linear transformation model and subsumes popular models from survival analysis, like the proportional hazards model and the proportional odds model. Core of the model is the assumption that an unspecified monotone…

  10. Modeling Information Accumulation in Psychological Tests Using Item Response Times

    ERIC Educational Resources Information Center

    Ranger, Jochen; Kuhn, Jörg-Tobias

    2015-01-01

    In this article, a latent trait model is proposed for the response times in psychological tests. The latent trait model is based on the linear transformation model and subsumes popular models from survival analysis, like the proportional hazards model and the proportional odds model. Core of the model is the assumption that an unspecified monotone…

  11. Checking the Assumptions of Rasch's Model for Speed Tests

    ERIC Educational Resources Information Center

    Jansen, M. G. H.; Glas, C. A. W.

    2005-01-01

    Two new tests for a model for the response times on pure speed tests by Rasch (1960) are proposed. The model is based on the assumption that the test response times are approximately gamma distributed, with known index parameters and unknown rate parameters. The rate parameters are decomposed in a subject ability parameter and a test difficulty…

  12. Correct CMOS IC defect models for quality testing

    NASA Technical Reports Server (NTRS)

    Soden, Jerry M.; Hawkins, Charles F.

    1993-01-01

    Leading edge, high reliability, and low escape CMOS IC test practices have now virtually removed the stuck-at fault model and replaced it with more defect-orientated models. Quiescent power supply current testing (I(sub DDQ)) combined with strategic use of high speed test patterns is the recommended approach to zero defect and high reliability testing goals. This paper reviews the reasons for the change in CMOS IC test practices and outlines an improved CMOS IC test methodology.

  13. An Error Score Model for Time-Limit Tests

    ERIC Educational Resources Information Center

    Ven, A. H. G. S. van der

    1976-01-01

    A more generalized error model for time-limit tests is developed. Model estimates are derived for right-attempted and wrong-attempted correlations both within the same test and between different tests. A comparison is made between observed correlations and their model counterparts and a fair agreement is found between observed and expected…

  14. The Internationalization of Testing and New Models of Test Delivery on the Internet

    ERIC Educational Resources Information Center

    Bartram, Dave

    2006-01-01

    The Internet has opened up a whole new set of opportunities for advancing the science of psychometrics and the technology of testing. It has also created some new challenges for those of us involved in test design and testing. In particular, we are seeing impacts from internationalization of testing and new models for test delivery. These are…

  15. 46 CFR 54.01-10 - Steam-generating pressure vessels (modifies U-1(g)).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Steam-generating pressure vessels (modifies U-1(g)). 54... ENGINEERING PRESSURE VESSELS General Requirements § 54.01-10 Steam-generating pressure vessels (modifies U-1(g)). (a) Pressure vessels in which steam is generated are classed as “Unfired Steam Boilers” except...

  16. WELLTON GOVERNMENT CAMP, PERMANENT GARAGE TYPE 1G. PLAN, ELEVATIONS, AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    WELLTON GOVERNMENT CAMP, PERMANENT GARAGE TYPE 1-G. PLAN, ELEVATIONS, AND SECTIONS. Drawing 50-308-4552, dated October 25, 1949. U.S. Department of the Interior, Bureau of Reclamation, Yuma, Arizona - Wellton-Mohawk Irrigation System, Permanent Garage Type 1-G, 30601 Wellton-Mohawk Drive, Wellton, Yuma County, AZ

  17. 46 CFR 54.01-10 - Steam-generating pressure vessels (modifies U-1(g)).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Steam-generating pressure vessels (modifies U-1(g)). 54.01-10 Section 54.01-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54.01-10 Steam-generating pressure vessels (modifies U-1(g...

  18. 46 CFR 54.01-10 - Steam-generating pressure vessels (modifies U-1(g)).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Steam-generating pressure vessels (modifies U-1(g)). 54.01-10 Section 54.01-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54.01-10 Steam-generating pressure vessels (modifies U-1(g...

  19. 46 CFR 54.01-10 - Steam-generating pressure vessels (modifies U-1(g)).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Steam-generating pressure vessels (modifies U-1(g)). 54.01-10 Section 54.01-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54.01-10 Steam-generating pressure vessels (modifies U-1(g...

  20. 46 CFR 54.01-10 - Steam-generating pressure vessels (modifies U-1(g)).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Steam-generating pressure vessels (modifies U-1(g)). 54.01-10 Section 54.01-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS General Requirements § 54.01-10 Steam-generating pressure vessels (modifies U-1(g...

  1. Association between cyclin D1 G870A polymorphism and hepatocellular carcinoma risk: a meta-analysis

    PubMed Central

    Luo, Tao; Chen, Jie; Liu, Jun-Jie; Li, Hang; You, Xue-Mei; Wang, Hong-Liang; Zhu, Shao-Liang; Li, Le-Qun

    2016-01-01

    Background Cyclin D1 (CCND1) G870A polymorphism may be associated with hepatocellular carcinoma (HCC) risk, but the results of previous studies were inconsistent. Available evidence was meta-analyzed to assess their potential association. Methods Databases PubMed, EMBASE, Cochrane Library, Web of Science, Chinese Biomedical Literature database, China National Knowledge Infrastructure, and Google Scholar were systematically searched. Meta-analyses were performed to investigate the association of G870A polymorphism with HCC risk by calculating odds ratios (ORs) and 95% confidence intervals (CIs) from the data of relevant case–control studies. Results Results of this meta-analysis of six case–control studies involving 1,030 cases and 1,683 controls indicate that G870A polymorphism was not associated with HCC risk in any of the five genetic models tested (recessive model: AA vs GG + AG: OR =1.38, 95% CI =0.95–2.00, P=0.09; dominant model: AG + AA vs GG: OR =1.38, 95% CI =0.87–2.20, P=0.17; homozygous model: AA vs GG: OR =1.60, 95% CI =0.87–2.94, P=0.13; heterozygous model: AG vs GG: OR =1.24, 95% CI =0.86–1.79, P=0.25; allelic model: A vs G: OR =1.30, 95% CI =0.95–1.80, P=0.10). Subgroup analyses according to ethnicity showing marginally significant association between this single nucleotide polymorphism and HCC risk indicate that G870A may be significantly associated with HCC risk in Caucasian populations (recessive model: AA vs GG + AG: OR =2.34, 95% CI =1.60–3.42, P<0.0001; dominant model: AG + AA vs GG: OR =2.44, 95% CI =1.19–4.97, P=0.01; homozygous model: AA vs GG: OR =3.42, 95% CI =1.80–6.50, P=0.0002; allelic model: A vs G: OR =2.06, 95% CI =1.31–3.24, P=0.002), but not in Asian populations. Conclusion Available evidence suggests that no significant association between G870A polymorphism and HCC risk was found in either total populations or Asian populations. However, significant association was found in Caucasian populations. These

  2. A Flexible Latent Trait Model for Response Times in Tests

    ERIC Educational Resources Information Center

    Ranger, Jochen; Kuhn, Jorg-Tobias

    2012-01-01

    Latent trait models for response times in tests have become popular recently. One challenge for response time modeling is the fact that the distribution of response times can differ considerably even in similar tests. In order to reduce the need for tailor-made models, a model is proposed that unifies two popular approaches to response time…

  3. State of the art hydraulic turbine model test

    NASA Astrophysics Data System (ADS)

    Fabre, Violaine; Duparchy, Alexandre; Andre, Francois; Larroze, Pierre-Yves

    2016-11-01

    Model tests are essential in hydraulic turbine development and related fields. The methods and technologies used to perform these tests show constant progress and provide access to further information. In addition, due to its contractual nature, the test demand evolves continuously in terms of quantity and accuracy. Keeping in mind that the principal aim of model testing is the transposition of the model measurements to the real machine, the measurements should be performed accurately, and a critical analysis of the model test results is required to distinguish the transposable hydraulic phenomena from the test rig interactions. Although the resonances’ effects are known and described in the IEC standard, their identification is difficult. Leaning on a strong experience of model testing, we will illustrate with a few examples of how to identify the potential problems induced by the test rig. This paper contains some of our best practices to obtain the most accurate, relevant, and independent test-rig measurements.

  4. Valid Testing Model for Admissions-Placement.

    ERIC Educational Resources Information Center

    Johnson, Berman E.

    1984-01-01

    Describes a study conducted at DeKalb Community College to compare placement levels established by the college's in-house Reading, English and Mathematics (REM) Test with Scholastic Aptitude Test scores. Discusses REM placement levels and their course alignments, internal challenges to the placement levels, and correlation study findings. (DMM)

  5. Optimization models for flight test scheduling

    NASA Astrophysics Data System (ADS)

    Holian, Derreck

    As threats around the world increase with nations developing new generations of warfare technology, the Unites States is keen on maintaining its position on top of the defense technology curve. This in return indicates that the U.S. military/government must research, develop, procure, and sustain new systems in the defense sector to safeguard this position. Currently, the Lockheed Martin F-35 Joint Strike Fighter (JSF) Lightning II is being developed, tested, and deployed to the U.S. military at Low Rate Initial Production (LRIP). The simultaneous act of testing and deployment is due to the contracted procurement process intended to provide a rapid Initial Operating Capability (IOC) release of the 5th Generation fighter. For this reason, many factors go into the determination of what is to be tested, in what order, and at which time due to the military requirements. A certain system or envelope of the aircraft must be assessed prior to releasing that capability into service. The objective of this praxis is to aide in the determination of what testing can be achieved on an aircraft at a point in time. Furthermore, it will define the optimum allocation of test points to aircraft and determine a prioritization of restrictions to be mitigated so that the test program can be best supported. The system described in this praxis has been deployed across the F-35 test program and testing sites. It has discovered hundreds of available test points for an aircraft to fly when it was thought none existed thus preventing an aircraft from being grounded. Additionally, it has saved hundreds of labor hours and greatly reduced the occurrence of test point reflight. Due to the proprietary nature of the JSF program, details regarding the actual test points, test plans, and all other program specific information have not been presented. Generic, representative data is used for example and proof-of-concept purposes. Apart from the data correlation algorithms, the optimization associated

  6. Test Driven Development of Scientific Models

    NASA Technical Reports Server (NTRS)

    Clune, Thomas L.

    2014-01-01

    Test-Driven Development (TDD), a software development process that promises many advantages for developer productivity and software reliability, has become widely accepted among professional software engineers. As the name suggests, TDD practitioners alternate between writing short automated tests and producing code that passes those tests. Although this overly simplified description will undoubtedly sound prohibitively burdensome to many uninitiated developers, the advent of powerful unit-testing frameworks greatly reduces the effort required to produce and routinely execute suites of tests. By testimony, many developers find TDD to be addicting after only a few days of exposure, and find it unthinkable to return to previous practices.After a brief overview of the TDD process and my experience in applying the methodology for development activities at Goddard, I will delve more deeply into some of the challenges that are posed by numerical and scientific software as well as tools and implementation approaches that should address those challenges.

  7. Detection of rare antigen-presenting cells through T cell-intrinsic meandering motility, mediated by Myo1g.

    PubMed

    Gérard, Audrey; Patino-Lopez, Genaro; Beemiller, Peter; Nambiar, Rajalakshmi; Ben-Aissa, Khadija; Liu, Yin; Totah, Fadi J; Tyska, Matthew J; Shaw, Stephen; Krummel, Matthew F

    2014-07-31

    To mount an immune response, T lymphocytes must successfully search for foreign material bound to the surface of antigen-presenting cells. How T cells optimize their chances of encountering and responding to these antigens is unknown. T cell motility in tissues resembles a random or Levy walk and is regulated in part by external factors including chemokines and lymph-node topology, but motility parameters such as speed and propensity to turn may also be cell intrinsic. Here we found that the unconventional myosin 1g (Myo1g) motor generates membrane tension, enforces cell-intrinsic meandering search, and enhances T-DC interactions during lymph-node surveillance. Increased turning and meandering motility, as opposed to ballistic motility, is enhanced by Myo1g. Myo1g acts as a "turning motor" and generates a form of cellular "flânerie." Modeling and antigen challenges show that these intrinsically programmed elements of motility search are critical for the detection of rare cognate antigen-presenting cells.

  8. Test Driven Development of Scientific Models

    NASA Technical Reports Server (NTRS)

    Clune, Thomas L.

    2012-01-01

    Test-Driven Development (TDD) is a software development process that promises many advantages for developer productivity and has become widely accepted among professional software engineers. As the name suggests, TDD practitioners alternate between writing short automated tests and producing code that passes those tests. Although this overly simplified description will undoubtedly sound prohibitively burdensome to many uninitiated developers, the advent of powerful unit-testing frameworks greatly reduces the effort required to produce and routinely execute suites of tests. By testimony, many developers find TDD to be addicting after only a few days of exposure, and find it unthinkable to return to previous practices. Of course, scientific/technical software differs from other software categories in a number of important respects, but I nonetheless believe that TDD is quite applicable to the development of such software and has the potential to significantly improve programmer productivity and code quality within the scientific community. After a detailed introduction to TDD, I will present the experience within the Software Systems Support Office (SSSO) in applying the technique to various scientific applications. This discussion will emphasize the various direct and indirect benefits as well as some of the difficulties and limitations of the methodology. I will conclude with a brief description of pFUnit, a unit testing framework I co-developed to support test-driven development of parallel Fortran applications.

  9. Cellular Expression, Trafficking, and Function of Two Isoforms of Human ULBP5/RAET1G

    PubMed Central

    Eagle, Robert A.; Flack, Gillian; Warford, Anthony; Martínez-Borra, Jesús; Jafferji, Insiya; Traherne, James A.; Ohashi, Maki; Boyle, Louise H.; Barrow, Alexander D.; Caillat-Zucman, Sophie; Young, Neil T.; Trowsdale, John

    2009-01-01

    Background The activating immunoreceptor NKG2D is expressed on Natural Killer (NK) cells and subsets of T cells. NKG2D contributes to anti-tumour and anti-viral immune responses in vitro and in vivo. The ligands for NKG2D in humans are diverse proteins of the MIC and ULBP/RAET families that are upregulated on the surface of virally infected cells and tumours. Two splicing variants of ULBP5/RAET1G have been cloned previously, but not extensively characterised. Methodology/Principal Findings We pursue a number of approaches to characterise the expression, trafficking, and function of the two isoforms of ULBP5/RAET1G. We show that both transcripts are frequently expressed in cell lines derived from epithelial cancers, and in primary breast cancers. The full-length transcript, RAET1G1, is predicted to encode a molecule with transmembrane and cytoplasmic domains that are unique amongst NKG2D ligands. Using specific anti-RAET1G1 antiserum to stain tissue microarrays we show that RAET1G1 expression is highly restricted in normal tissues. RAET1G1 was expressed at a low level in normal gastrointestinal epithelial cells in a similar pattern to MICA. Both RAET1G1 and MICA showed increased expression in the gut of patients with celiac disease. In contrast to healthy tissues the RAET1G1 antiserum stained a wide variety or different primary tumour sections. Both endogenously expressed and transfected RAET1G1 was mainly found inside the cell, with a minority of the protein reaching the cell surface. Conversely the truncated splicing variant of RAET1G2 was shown to encode a soluble molecule that could be secreted from cells. Secreted RAET1G2 was shown to downregulate NKG2D receptor expression on NK cells and hence may represent a novel tumour immune evasion strategy. Conclusions/Significance We demonstrate that the expression patterns of ULBP5RAET1G are very similar to the well-characterised NKG2D ligand, MICA. However the two isoforms of ULBP5/RAET1G have very different cellular

  10. Test report SEPS solar array root section model

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The fabrication and test of a solar array functional root section model to verify preliminary array design concepts is presented. The root section model is full scale width and contains a model array blanket. The blanket contains 1/8 live electrical modules and the remainder contains solar cell mass simulators. A storable Astromast is used for array blanket extension and retraction. The model component and system assembly hardware, tests, and test results are described.

  11. Information Model for Machine-Tool-Performance Tests

    PubMed Central

    Lee, Y. Tina; Soons, Johannes A.; Donmez, M. Alkan

    2001-01-01

    This report specifies an information model of machine-tool-performance tests in the EXPRESS [1] language. The information model provides a mechanism for describing the properties and results of machine-tool-performance tests. The objective of the information model is a standardized, computer-interpretable representation that allows for efficient archiving and exchange of performance test data throughout the life cycle of the machine. The report also demonstrates the implementation of the information model using three different implementation methods. PMID:27500031

  12. Model Based Analysis and Test Generation for Flight Software

    NASA Technical Reports Server (NTRS)

    Pasareanu, Corina S.; Schumann, Johann M.; Mehlitz, Peter C.; Lowry, Mike R.; Karsai, Gabor; Nine, Harmon; Neema, Sandeep

    2009-01-01

    We describe a framework for model-based analysis and test case generation in the context of a heterogeneous model-based development paradigm that uses and combines Math- Works and UML 2.0 models and the associated code generation tools. This paradigm poses novel challenges to analysis and test case generation that, to the best of our knowledge, have not been addressed before. The framework is based on a common intermediate representation for different modeling formalisms and leverages and extends model checking and symbolic execution tools for model analysis and test case generation, respectively. We discuss the application of our framework to software models for a NASA flight mission.

  13. Airship Model Tests in the Variable Density Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Abbott, Ira H

    1932-01-01

    This report presents the results of wind tunnel tests conducted to determine the aerodynamic characteristics of airship models. Eight Goodyear-Zeppelin airship models were tested in the original closed-throat tunnel. After the tunnel was rebuilt with an open throat a new model was tested, and one of the Goodyear-Zeppelin models was retested. The results indicate that much may be done to determine the drag of airships from evaluations of the pressure and skin-frictional drags on models tested at large Reynolds number.

  14. Similitude requirements and scaling relationships as applied to model testing

    NASA Technical Reports Server (NTRS)

    Wolowicz, C. H.; Brown, J. S., Jr.; Gilbert, W. P.

    1979-01-01

    The similitude requirements for the most general test conditions are presented. These similitude requirements are considered in relation to the scaling relationships, test technique, test conditions (including supersonic flow), and test objectives. Particular emphasis is placed on satisfying the various similitude requirements for incompressible and compressible flow conditions. For free flying models tests, the test velocities for incompressible flow are scaled from Froude number similitude requirements and those for compressible flow are scaled from Mach number similitude requirements. The limitations of various test techniques are indicated, with emphasis on the free flying model.

  15. Pullout test model for extensible reinforcement

    NASA Astrophysics Data System (ADS)

    Gurung, N.; Iwao, Y.; Madhav, M. R.

    1999-10-01

    A formulation for the analysis of pullout test on highly extensible planar reinforcement is presented. The non-linear differential equation for pullout mechanism was expressed in non-dimensional form and solved numerically using the Gauss-Siedel technique. Parametric study was carried out for various ranges of relative stiffnesses, and relative bond resistances. Normalized load-displacement relations and the variations of pullout force and reinforcement displacements along the length of reinforcement are presented graphically. A method for the estimation of the interface interaction parameters from a pre-failure test is also given. The numerical predictions compare well with the available experimental pullout test results for various geotextiles, polymers and nylon geosynthetics.

  16. In vitro characterization of the α-thalassemia point mutation HBA2:c.95+1G>A [IVS-I-1(G>A) (α2)].

    PubMed

    Qadah, Talal; Finlayson, Jill; Ghassemifar, Reza

    2012-01-01

    The α-thalassemias are a group of disorders occurring as a result of decreased synthesis of α-globin chains, most commonly due to deletions of α-globin genes. Detection of α-thalassemia (α-thal) caused by point mutations has increased during the past few years and more than 70 different point mutations have been reported for the α1- and α2-globin genes. The mutation at the splice donor site of the first intervening sequence [IVS-I-1 (G>A)] of the α2-globin gene, HBA2:c.95+1G>A, is thought to cause a thalassemic phenotype by interfering with and preventing the normal splicing of pre-mRNA. We developed an in vitro expression system to study α-globin gene point mutations at the molecular and cellular levels. The expression vector carrying the HBA2:c.95+1G>A mutation (α2G(IVS-I-1G>A)) was created using site-directed mutagenesis of a wild type (WT) construct of the α2-globin gene (α2G(2034WT)). Gene expression experiments in human bladder carcinoma 5637 cells were carried out using sequence verified WT and mutated clones. Complementary DNA synthesis and polymerase chain reaction (PCR) analysis showed normal α2-globin transcripts from cells transfected with the WT vector, but aberrant transcripts from cells transfected with the mutated vector carrying the splice donor site mutation. In the presence of the G>A mutation, normal splicing does not occur, and a cryptic splice site 49 bp upstream of the normal site is used. The translation of this product produces a premature termination codon, thus resulting in a thalassemic phenotype.

  17. Using the NPSS Environment to Model an Altitude Test Facility

    NASA Technical Reports Server (NTRS)

    Lavelle, Thomas M.; Owen, Albert K.; Huffman, Brian C.

    2013-01-01

    An altitude test facility was modeled using Numerical Propulsion System Simulation (NPSS). This altitude test facility model represents the most detailed facility model developed in the NPSS architecture. The current paper demonstrates the use of the NPSS system to define the required operating range of a component for the facility. A significant number of additional component models were easily developed to complete the model. Discussed in this paper are the additional components developed and what was done in the development of these components.

  18. Development and application of an acceptance testing model

    NASA Technical Reports Server (NTRS)

    Pendley, Rex D.; Noonan, Caroline H.; Hall, Kenneth R.

    1992-01-01

    The process of acceptance testing large software systems for NASA has been analyzed, and an empirical planning model of the process constructed. This model gives managers accurate predictions of the staffing needed, the productivity of a test team, and the rate at which the system will pass. Applying the model to a new system shows a high level of agreement between the model and actual performance. The model also gives managers an objective measure of process improvement.

  19. A Functional Test Platform for the Community Land Model

    SciTech Connect

    Xu, Yang; Thornton, Peter E; King, Anthony Wayne; Steed, Chad A; Gu, Lianhong; Schuchart, Joseph

    2014-01-01

    A functional test platform is presented to create direct linkages between site measurements and the process-based ecosystem model within the Community Earth System Models (CESM). The platform consists of three major parts: 1) interactive user interfaces, 2) functional test model and 3) observational datasets. It provides much needed integration interfaces for both field experimentalists and ecosystem modelers to improve the model s representation of ecosystem processes within the CESM framework without large software overhead.

  20. Surface characterization through shape oscillations of drops in microgravity and 1-g

    NASA Technical Reports Server (NTRS)

    Apfel, Robert E.; Holt, R. Glynn; Tian, Yuren; Shi, Tao; Zheng, Xiao-Yu

    1994-01-01

    The goal of these experiments is to determine the rheological properties of liquid drops of single or multiple components in the presence or absence of surface active materials by exciting drops into their quadrupole resonance and observing their free decay. The resulting data coupled with appropriate theory should give a better description of the physics of the underlying phenomena, providing a better foundation than earlier empirical results could. The space environment makes an idealized geometry available (spherical drops) so that theory and experiment can be properly compared, and allows a 'clean' environment, by which is meant an environment in which no solid surfaces come in contact with the drops during the test period. Moreover, by considering the oscillations of intentionally deformed drops in microgravity, a baseline is established for interpreting surface characterization experiments done on the ground by other groups and ours. Experiments performed on the United States Microgravity Laboratory Laboratory (USML-1) demonstrated that shape oscillation experiments could be performed over a wide parameter range, and with a variety of surfactant materials. Results, however, were compromised by an unexpected, slow drop tumbling, some problems with droplet injection, and the presence of bubbles in the drop samples. Nevertheless, initial data suggests that the space environment will be useful in providing baseline data that can serve to validate theory and permit quantitative materials characterization at 1-g.

  1. Precipitation scavenging models: Sensitivities, tests, and applications

    SciTech Connect

    Hales, J.M.

    1991-07-01

    Multiphase'' atmospheric-chemistry models can be described as atmospheric-pollutant simulations that explicitly differentiate between physical phases in the atmosphere (.e.g., gas, cloud water, rain water, snow,...), and directly compute chemical transport and transformation behavior between and within each of these individual phases. Initially formulated for specific application to precipitation-scavenging analysis, many attributes of these models have become incorporated into the more general atmospheric-chemisty codes as well. During the past few years, several of these multiphase precipitation-scavenging models have been developed to the point where they can be applied, in a moderately straightforward fashion, by members of the extended atmospheric sciences community. This presentation provides a brief overview of several aspects of a number of these models, including their structure, their application, their sensitivities and uncertainty levels, their evaluation against field measurements, and their availability.

  2. Precipitation scavenging models: Sensitivities, tests, and applications

    SciTech Connect

    Hales, J.M.

    1991-07-01

    ``Multiphase`` atmospheric-chemistry models can be described as atmospheric-pollutant simulations that explicitly differentiate between physical phases in the atmosphere (.e.g., gas, cloud water, rain water, snow,...), and directly compute chemical transport and transformation behavior between and within each of these individual phases. Initially formulated for specific application to precipitation-scavenging analysis, many attributes of these models have become incorporated into the more general atmospheric-chemisty codes as well. During the past few years, several of these multiphase precipitation-scavenging models have been developed to the point where they can be applied, in a moderately straightforward fashion, by members of the extended atmospheric sciences community. This presentation provides a brief overview of several aspects of a number of these models, including their structure, their application, their sensitivities and uncertainty levels, their evaluation against field measurements, and their availability.

  3. Beyond Testing: Empirical Models of Insurance Markets

    PubMed Central

    Einav, Liran; Finkelstein, Amy; Levin, Jonathan

    2011-01-01

    We describe recent advances in the empirical analysis of insurance markets. This new research proposes ways to estimate individual demand for insurance and the relationship between prices and insurer costs in the presence of adverse and advantageous selection. We discuss how these models permit the measurement of welfare distortions arising from asymmetric information and the welfare consequences of potential government policy responses. We also discuss some challenges in modeling imperfect competition between insurers and outline a series of open research questions. PMID:21572939

  4. A Model for Random Student Drug Testing

    ERIC Educational Resources Information Center

    Nelson, Judith A.; Rose, Nancy L.; Lutz, Danielle

    2011-01-01

    The purpose of this case study was to examine random student drug testing in one school district relevant to: (a) the perceptions of students participating in competitive extracurricular activities regarding drug use and abuse; (b) the attitudes and perceptions of parents, school staff, and community members regarding student drug involvement; (c)…

  5. Free-vibration characteristics of a large split-blanket solar array in a 1-g field

    NASA Technical Reports Server (NTRS)

    Shaker, F. J.

    1976-01-01

    Two methods for studying the free vibration characteristics of a large split blanket solar array in both a 0-g and a 1-g cantilevered configuration are presented. The 0-g configuration corresponds to an in-orbit configuration of the array; the 1-g configuration is a typical ground test configuration. The first method applies the equations of continuum mechanics to determine the mode shapes and frequencies of the array; the second method uses the Rayleigh-Ritz approach. In the Rayleigh-Ritz method the array displacements are represented by string modes and cantilevered beam modes. The results of this investigation are summarized by a series of graphs illustrating the effects of various array parameters on the mode shapes and frequencies of the system. The results of the two methods are also compared in tabular form.

  6. Modulation of statolith mass and grouping in white clover (Trifolium repens) growth in 1-g, microgravity and on the clinostat

    NASA Technical Reports Server (NTRS)

    Smith, J. D.; Todd, P.; Staehelin, L. A.

    1997-01-01

    Current models of gravity perception in higher plants focus on the buoyant weight of starch-filled amyloplasts as the initial gravity signal susceptor (statolith). However, no tests have yet determined if statolith mass is regulated to increase or decrease gravity stimulus to the plant. To this end, the root caps of white clover (Trifolium repens) grown in three gravity environments with three different levels of gravity stimulation have been examined: (i) 1-g control with normal static gravistimulation, (ii) on a slow clinostat with constant gravistimulation, and (iii) in the stimulus-free microgravity aboard the Space Shuttle. Seedlings were germinated and grown in the BioServe Fluid Processing Apparatus and root cap structure was examined at both light and electron microscopic levels, including three-dimensional cell reconstruction from serial sections. Quantitative analysis of the electron micrographs demonstrated that the starch content of amyloplasts varied with seedling age but not gravity condition. It was also discovered that, unlike in starch storage amyloplasts, all of the starch granules of statolith amyloplasts were encompassed by a fine filamentous, ribosome-excluding matrix. From light micrographic 3-D cell reconstructions, the absolute volume, number, and positional relationships between amyloplasts showed (i) that individual amyloplast volume increased in microgravity but remained constant in seedlings grown for up to three days on the clinostat, (ii) the number of amyloplasts per cell remained unchanged in microgravity but decreased on the clinostat, and (iii) the three-dimensional positions of amyloplasts were not random. Instead amyloplasts in microgravity were grouped near the cell centers while those from the clinostat appeared more dispersed. Taken together, these observations suggest that changing gravity stimulation can elicit feedback control over statolith mass by changing the size, number, and grouping of amyloplasts. These results

  7. Modulation of statolith mass and grouping in white clover (Trifolium repens) growth in 1-g, microgravity and on the clinostat

    NASA Technical Reports Server (NTRS)

    Smith, J. D.; Todd, P.; Staehelin, L. A.

    1997-01-01

    Current models of gravity perception in higher plants focus on the buoyant weight of starch-filled amyloplasts as the initial gravity signal susceptor (statolith). However, no tests have yet determined if statolith mass is regulated to increase or decrease gravity stimulus to the plant. To this end, the root caps of white clover (Trifolium repens) grown in three gravity environments with three different levels of gravity stimulation have been examined: (i) 1-g control with normal static gravistimulation, (ii) on a slow clinostat with constant gravistimulation, and (iii) in the stimulus-free microgravity aboard the Space Shuttle. Seedlings were germinated and grown in the BioServe Fluid Processing Apparatus and root cap structure was examined at both light and electron microscopic levels, including three-dimensional cell reconstruction from serial sections. Quantitative analysis of the electron micrographs demonstrated that the starch content of amyloplasts varied with seedling age but not gravity condition. It was also discovered that, unlike in starch storage amyloplasts, all of the starch granules of statolith amyloplasts were encompassed by a fine filamentous, ribosome-excluding matrix. From light micrographic 3-D cell reconstructions, the absolute volume, number, and positional relationships between amyloplasts showed (i) that individual amyloplast volume increased in microgravity but remained constant in seedlings grown for up to three days on the clinostat, (ii) the number of amyloplasts per cell remained unchanged in microgravity but decreased on the clinostat, and (iii) the three-dimensional positions of amyloplasts were not random. Instead amyloplasts in microgravity were grouped near the cell centers while those from the clinostat appeared more dispersed. Taken together, these observations suggest that changing gravity stimulation can elicit feedback control over statolith mass by changing the size, number, and grouping of amyloplasts. These results

  8. Modulation of statolith mass and grouping in white clover (Trifolium repens) growth in 1-g, microgravity and on the clinostat.

    PubMed

    Smith, J D; Todd, P; Staehelin, L A

    1997-12-01

    Current models of gravity perception in higher plants focus on the buoyant weight of starch-filled amyloplasts as the initial gravity signal susceptor (statolith). However, no tests have yet determined if statolith mass is regulated to increase or decrease gravity stimulus to the plant. To this end, the root caps of white clover (Trifolium repens) grown in three gravity environments with three different levels of gravity stimulation have been examined: (i) 1-g control with normal static gravistimulation, (ii) on a slow clinostat with constant gravistimulation, and (iii) in the stimulus-free microgravity aboard the Space Shuttle. Seedlings were germinated and grown in the BioServe Fluid Processing Apparatus and root cap structure was examined at both light and electron microscopic levels, including three-dimensional cell reconstruction from serial sections. Quantitative analysis of the electron micrographs demonstrated that the starch content of amyloplasts varied with seedling age but not gravity condition. It was also discovered that, unlike in starch storage amyloplasts, all of the starch granules of statolith amyloplasts were encompassed by a fine filamentous, ribosome-excluding matrix. From light micrographic 3-D cell reconstructions, the absolute volume, number, and positional relationships between amyloplasts showed (i) that individual amyloplast volume increased in microgravity but remained constant in seedlings grown for up to three days on the clinostat, (ii) the number of amyloplasts per cell remained unchanged in microgravity but decreased on the clinostat, and (iii) the three-dimensional positions of amyloplasts were not random. Instead amyloplasts in microgravity were grouped near the cell centers while those from the clinostat appeared more dispersed. Taken together, these observations suggest that changing gravity stimulation can elicit feedback control over statolith mass by changing the size, number, and grouping of amyloplasts. These results

  9. Testing proportionality in the proportional odds model fitted with GEE.

    PubMed

    Stiger, T R; Barnhart, H X; Williamson, J M

    1999-06-15

    Generalized estimating equations (GEE) methodology as proposed by Liang and Zeger has received widespread use in the analysis of correlated binary data. Miller et al. and Lipsitz et al. extended GEE to correlated nominal and ordinal categorical data; in particular, they used GEE for fitting McCullagh's proportional odds model. In this paper, we consider robust (that is, empirically corrected) and model-based versions of both a score test and a Wald test for assessing the assumption of proportional odds in the proportional odds model fitted with GEE. The Wald test is based on fitting separate multiple logistic regression models for each dichotomization of the response variable, whereas the score test requires fitting just the proportional odds model. We evaluate the proposed tests in small to moderate samples by simulating data from a series of simple models. We illustrate the use of the tests on three data sets from medical studies.

  10. Myo1g is an active player in maintaining cell stiffness in B-lymphocytes.

    PubMed

    López-Ortega, O; Ovalle-García, E; Ortega-Blake, I; Antillón, A; Chávez-Munguía, B; Patiño-López, G; Fragoso-Soriano, R; Santos-Argumedo, L

    2016-05-01

    B-lymphocytes are migrating cells that specialize in antigen presentation, antibody secretion, and endocytosis; these processes implicate the modulation of plasma membrane elasticity. Cell stiffness is a force generated by the interaction between the actin-cytoskeleton and the plasma membrane, which requires the participation of several proteins. These proteins include class I myosins, which are now considered to play a role in controlling membrane-cytoskeleton interactions. In this study, we identified the motor protein Myosin 1g (Myo1g) as a mediator of this phenomenon. The absence of Myo1g decreased the cell stiffness, affecting cell adhesion, cell spreading, phagocytosis, and endocytosis in B-lymphocytes. The results described here reveal a novel molecular mechanism by which Myo1g mediates and regulates cell stiffness in B-lymphocytes. © 2016 Wiley Periodicals, Inc.

  11. Landing Procedure in Model Ditching Tests of Bf 109

    NASA Technical Reports Server (NTRS)

    Sottorf, W.

    1949-01-01

    The purpose of the model tests is to clarify the motions in the alighting on water of a land plane. After discussion of the model laws, the test method and test procedure are described. The deceleration-time-diagrams of the landing of a model of the Bf 109 show a high deceleration peek of greater than 20g which can be lowered to 4 to 6g by radiator cowling and brake skid.

  12. Testing Software Development Project Productivity Model

    NASA Astrophysics Data System (ADS)

    Lipkin, Ilya

    Software development is an increasingly influential factor in today's business environment, and a major issue affecting software development is how an organization estimates projects. If the organization underestimates cost, schedule, and quality requirements, the end results will not meet customer needs. On the other hand, if the organization overestimates these criteria, resources that could have been used more profitably will be wasted. There is no accurate model or measure available that can guide an organization in a quest for software development, with existing estimation models often underestimating software development efforts as much as 500 to 600 percent. To address this issue, existing models usually are calibrated using local data with a small sample size, with resulting estimates not offering improved cost analysis. This study presents a conceptual model for accurately estimating software development, based on an extensive literature review and theoretical analysis based on Sociotechnical Systems (STS) theory. The conceptual model serves as a solution to bridge organizational and technological factors and is validated using an empirical dataset provided by the DoD. Practical implications of this study allow for practitioners to concentrate on specific constructs of interest that provide the best value for the least amount of time. This study outlines key contributing constructs that are unique for Software Size E-SLOC, Man-hours Spent, and Quality of the Product, those constructs having the largest contribution to project productivity. This study discusses customer characteristics and provides a framework for a simplified project analysis for source selection evaluation and audit task reviews for the customers and suppliers. Theoretical contributions of this study provide an initial theory-based hypothesized project productivity model that can be used as a generic overall model across several application domains such as IT, Command and Control

  13. Calpastatin inhibits motor neuron death and increases survival of hSOD1(G93A) mice.

    PubMed

    Rao, Mala V; Campbell, Jabbar; Palaniappan, Arti; Kumar, Asok; Nixon, Ralph A

    2016-04-01

    Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease with a poorly understood cause and no effective treatment. Given that calpains mediate neurodegeneration in other pathological states and are abnormally activated in ALS, we investigated the possible ameliorative effects of inhibiting calpain over-activation in hSOD1(G93A) transgenic (Tg) mice in vivo by neuron-specific over-expression of calpastatin (CAST), the highly selective endogenous inhibitor of calpains. Our data indicate that over-expression of CAST in hSOD1(G93A) mice, which lowered calpain activation to levels comparable to wild-type mice, inhibited the abnormal breakdown of cytoskeletal proteins (spectrin, MAP2 and neurofilaments), and ameliorated motor axon loss. Disease onset in hSOD1(G93A) /CAST mice compared to littermate hSOD1(G93A) mice is delayed, which accounts for their longer time of survival. We also find that neuronal over-expression of CAST in hSOD1(G93A) transgenic mice inhibited production of putative neurotoxic caspase-cleaved tau and activation of Cdk5, which have been implicated in neurodegeneration in ALS models, and also reduced the formation of SOD1 oligomers. Our data indicate that inhibition of calpain with CAST is neuroprotective in an ALS mouse model. CAST (encoding calpastatin) inhibits hyperactivated calpain to prevent motor neuron disease operating through a cascade of events as indicated in the schematic, with relevance to amyotrophic lateral sclerosis (ALS). We propose that over-expression of CAST in motor neurons of hSOD1(G93A) mice inhibits activation of CDK5, breakdown of cytoskeletal proteins (NFs, MAP2 and Tau) and regulatory molecules (Cam Kinase IV, Calcineurin A), and disease-causing proteins (TDP-43, α-Synuclein and Huntingtin) to prevent neuronal loss and delay neurological deficits. In our experiments, CAST could also inhibit cleavage of Bid, Bax, AIF to prevent mitochondrial, ER and lysosome-mediated cell death mechanisms. Similarly, CAST

  14. Oxygen consumption during cold exposure at 2.1 G in rats adapted to hypergravic fields

    NASA Technical Reports Server (NTRS)

    Horowitz, J.; Patterson, S.; Monson, C.

    1985-01-01

    The thermoregulation ability of rats exposed to various gravitational fields is examined. Male Sprague-Dawley rats were exposed to 22 C and 1 G, and 9 C and 2.1 G in experiment one, 1 G, 2.4 G, 5.8 G and 22 + or - 1.5 C in experiment two, and 1 G, 19-22 C, and 5 C in experiment three. It is observed that the core temperature in the control rats was 36.8 + or 0.4 C at 22C and 30.8 + or - 0.6 C at 9 C, and oxygen consumption dropped from 37 + or - 0.3 C core temperature at 22 C, 36.4 + or - 0.3 C at 9 C, 0.4 oxygen consumption was 8.18 + or - 0.9 ml/min at 22 C, and 14.2 + or - 0.4 ml/min at 9 C. The data from experiment two reveal that tail temperature in the control rats peaked at 2.4 G and at 5.8 G for the acclimated rats, and in experiment three a greater decrease in core temperature is detected in the 2.1-G rats. It is noted that prior acclimation to 2.1 G enhances the thermoregulation ability when exposed to the cold.

  15. Lack of Association of the APOL1 G3 Haplotype in African Americans with ESRD.

    PubMed

    Palmer, Nicholette D; Ng, Maggie C Y; Langefeld, Carl D; Divers, Jasmin; Lea, Janice P; Okusa, Mark D; Kimberly, Robert P; Bowden, Donald W; Freedman, Barry I

    2015-05-01

    Apolipoprotein L1 gene (APOL1) G1 and G2 variants are strongly associated with progressive nondiabetic nephropathy in populations with recent African ancestry. Selection for these variants occurred as a result of protection from human African trypanosomiasis (HAT). Resequencing of this region in 10 genetically and geographically distinct African populations residing in HAT endemic regions identified eight single nucleotide polymorphisms (SNPs) in strong linkage disequilibrium and comprising a novel G3 haplotype. To determine whether the APOL1 G3 haplotype was associated with nephropathy, G1, G2, and G3 SNPs and 70 ancestry informative markers spanning the genome were genotyped in 937 African Americans with nondiabetic ESRD, 965 African Americans with type 2 diabetes-associated ESRD, and 1029 non-nephropathy controls. In analyses adjusting for age, sex, APOL1 G1/G2 risk (recessive), and global African ancestry, the G3 haplotype was not significantly associated with ESRD (P=0.05 for nondiabetic ESRD, P=0.57 for diabetes-associated ESRD, and P=0.27 for all-cause ESRD). We conclude that variation in APOL1 G3 makes a nominal, if any, contribution to ESRD in African Americans; G1 and G2 variants explain the vast majority of nondiabetic nephropathy susceptibility. Copyright © 2015 by the American Society of Nephrology.

  16. Statistical and Practical Significance of the Likelihood Ratio Test of the Linear Logistic Test Model versus the Rasch Model

    ERIC Educational Resources Information Center

    Alexandrowicz, Rainer W.

    2011-01-01

    The linear logistic test model (LLTM) is a valuable and approved tool in educational research, as it allows for modelling cognitive components involved in a cognitive task. It allows for a rigorous assessment of fit by means of a Likelihood Ratio Test (LRT). This approach is genuine to the Rasch family of models, yet it suffers from the unsolved…

  17. Validated intraclass correlation statistics to test item performance models.

    PubMed

    Courrieu, Pierre; Brand-D'abrescia, Muriele; Peereman, Ronald; Spieler, Daniel; Rey, Arnaud

    2011-03-01

    A new method, with an application program in Matlab code, is proposed for testing item performance models on empirical databases. This method uses data intraclass correlation statistics as expected correlations to which one compares simple functions of correlations between model predictions and observed item performance. The method rests on a data population model whose validity for the considered data is suitably tested and has been verified for three behavioural measure databases. Contrarily to usual model selection criteria, this method provides an effective way of testing under-fitting and over-fitting, answering the usually neglected question "does this model suitably account for these data?"

  18. Hydrodynamical comparison test of solar models

    NASA Astrophysics Data System (ADS)

    Bach, K.; Kim, Y.-C.

    2012-12-01

    We present three dimensional radiation-hydrodynamical (RHD) simulations for solar surface convection based on three most recent solar mixtures: Grevesse & Sauval (1998), Asplund, Grevesse & Sauval (2005), and Asplund, Grevesse, Sauval & Scott (2009). The outer convection zone of the Sun is an extremely turbulent region composed of partly ionized compressible gases at high temperature. The super-adiabatic layer (SAL) is the transition region where the transport of energy changes drastically from convection to radiation. In order to describe physical processes accurately, a realistic treatment of radiation should be considered as well as convection. However, newly updated solar mixtures that are established from radiation-hydrodynamics do not generate properly internal structures estimated by helioseismology. In order to address this fundamental problem, solar models are constructed consistently based on each mixture and used as initial configurations for radiation-hydrodynamical simulations. From our simulations, we find that the turbulent flows in each model are statistically similar in the SAL.

  19. Mountain Bike Wheel Endurance Testing and Modeling

    DTIC Science & Technology

    2012-01-01

    simulating bike and rider mass, is added using weights supported near the wheel hub axis. The pivoting assembly is raised and lowered on pneumatic ...A lower frequency oscillation with period ~0.2 seconds corresponds with the 5 Hz natural frequency of the weighted pivot arm on the pneumatic tire...Empirical Model for Determining the Radial Force-Deflection Characteristics of Off-Road bicycle Tyres ,” International Journal of Vehicle Design, 17 (4

  20. A magnetorheological actuation system: test and model

    NASA Astrophysics Data System (ADS)

    John, Shaju; Chaudhuri, Anirban; Wereley, Norman M.

    2008-04-01

    Self-contained actuation systems, based on frequency rectification of the high frequency motion of an active material, can produce high force and stroke output. Magnetorheological (MR) fluids are active fluids whose rheological properties can be altered by the application of a magnetic field. By using MR fluids as the energy transmission medium in such hybrid devices, a valving system with no moving parts can be implemented and used to control the motion of an output cylinder shaft. The MR fluid based valves are configured in the form of an H-bridge to produce bi-directional motion in an output cylinder by alternately applying magnetic fields in the two opposite arms of the bridge. The rheological properties of the MR fluid are modeled using both Bingham plastic and bi-viscous models. In this study, the primary actuation is performed using a compact terfenol-D rod driven pump and frequency rectification of the rod motion is done using passive reed valves. The pump and reed valve configuration along with MR fluidic valves form a compact hydraulic actuation system. Actuator design, analysis and experimental results are presented in this paper. A time domain model of the actuator is developed and validated using experimental data.

  1. CuII(atsm) improves the neurological phenotype and survival of SOD1G93A mice and selectively increases enzymatically active SOD1 in the spinal cord

    PubMed Central

    Hilton, James B.; Mercer, Stephen W.; Lim, Nastasia K. H.; Faux, Noel G.; Buncic, Gojko; Beckman, Joseph S.; Roberts, Blaine R.; Donnelly, Paul S.; White, Anthony R.; Crouch, Peter J.

    2017-01-01

    Ubiquitous expression of mutant Cu/Zn-superoxide dismutase (SOD1) selectively affects motor neurons in the central nervous system (CNS), causing the adult-onset degenerative disease amyotrophic lateral sclerosis (ALS). The CNS-specific impact of ubiquitous mutant SOD1 expression is recapitulated in transgenic mouse models of the disease. Here we present outcomes for the metallo-complex CuII(atsm) tested for therapeutic efficacy in mice expressing SOD1G93A on a mixed genetic background. Oral administration of CuII(atsm) delayed the onset of neurological symptoms, improved locomotive capacity and extended overall survival. Although the ALS-like phenotype of SOD1G93A mice is instigated by expression of the mutant SOD1, we show the improved phenotype of the CuII(atsm)-treated animals involves an increase in mature mutant SOD1 protein in the disease-affected spinal cord, where concomitant increases in copper and SOD1 activity are also evident. In contrast to these effects in the spinal cord, treating with CuII(atsm) had no effect in liver on either mutant SOD1 protein levels or its activity, indicating a CNS-selective SOD1 response to the drug. These data provide support for CuII(atsm) as a treatment option for ALS as well as insight to the CNS-selective effects of mutant SOD1. PMID:28205575

  2. Dynamic test/analysis correlation using reduced analytical models

    NASA Technical Reports Server (NTRS)

    Mcgowan, Paul E.; Angelucci, A. F.; Javeed, Mehzad

    1992-01-01

    Test/analysis correlation is an important aspect of the verification of analysis models which are used to predict on-orbit response characteristics of large space structures. This paper presents results of a study using reduced analysis models for performing dynamic test/analysis correlation. The reduced test-analysis model (TAM) has the same number and orientation of DOF as the test measurements. Two reduction methods, static (Guyan) reduction and the Improved Reduced System reduction, are applied to the test/analysis correlation of a laboratory truss structure. Simulated test results and modal test data are used to examine the performance of each method. It is shown that selection of DOF to be retained in the TAM is critical when large structural masses are involved. In addition, the use of modal test results may provide difficulties in TAM accuracy even if a large number of DOF are retained in the TAM.

  3. Dynamic test/analysis correlation using reduced analytical models

    NASA Technical Reports Server (NTRS)

    Mcgowan, Paul E.; Angelucci, A. Filippo; Javeed, Mehzad

    1992-01-01

    Test/analysis correlation is an important aspect of the verification of analysis models which are used to predict on-orbit response characteristics of large space structures. This paper presents results of a study using reduced analysis models for performing dynamic test/analysis correlation. The reduced test-analysis model (TAM) has the same number and orientation of DOF as the test measurements. Two reduction methods, static (Guyan) reduction and the Improved Reduced System (IRS) reduction, are applied to the test/analysis correlation of a laboratory truss structure. Simulated test results and modal test data are used to examine the performance of each method. It is shown that selection of DOF to be retained in the TAM is critical when large structural masses are involved. In addition, the use of modal test results may provide difficulties in TAM accuracy even if a large number of DOF are retained in the TAM.

  4. Tests of Hypotheses Arising In the Correlated Random Coefficient Model*

    PubMed Central

    Heckman, James J.; Schmierer, Daniel

    2010-01-01

    This paper examines the correlated random coefficient model. It extends the analysis of Swamy (1971), who pioneered the uncorrelated random coefficient model in economics. We develop the properties of the correlated random coefficient model and derive a new representation of the variance of the instrumental variable estimator for that model. We develop tests of the validity of the correlated random coefficient model against the null hypothesis of the uncorrelated random coefficient model. PMID:21170148

  5. Tests of Hypotheses Arising In the Correlated Random Coefficient Model.

    PubMed

    Heckman, James J; Schmierer, Daniel

    2010-11-01

    This paper examines the correlated random coefficient model. It extends the analysis of Swamy (1971), who pioneered the uncorrelated random coefficient model in economics. We develop the properties of the correlated random coefficient model and derive a new representation of the variance of the instrumental variable estimator for that model. We develop tests of the validity of the correlated random coefficient model against the null hypothesis of the uncorrelated random coefficient model.

  6. Upgraded Analytical Model of the Cylinder Test

    SciTech Connect

    Souers, P. Clark; Lauderbach, Lisa; Garza, Raul; Ferranti, Louis; Vitello, Peter

    2013-03-15

    A Gurney-type equation was previously corrected for wall thinning and angle of tilt, and now we have added shock wave attenuation in the copper wall and air gap energy loss. Extensive calculations were undertaken to calibrate the two new energy loss mechanisms across all explosives. The corrected Gurney equation is recommended for cylinder use over the original 1943 form. The effect of these corrections is to add more energy to the adiabat values from a relative volume of 2 to 7, with low energy explosives having the largest correction. The data was pushed up to a relative volume of about 15 and the JWL parameter ω was obtained directly. The total detonation energy density was locked to the v=7 adiabat energy density, so that the Cylinder test gives all necessary values needed to make a JWL.

  7. Upgraded Analytical Model of the Cylinder Test

    SciTech Connect

    Souers, P. Clark; Lauderbach, Lisa; Garza, Raul; Ferranti, Louis; Vitello, Peter

    2013-03-15

    A Gurney-type equation was previously corrected for wall thinning and angle of tilt, and now we have added shock wave attenuation in the copper wall and air gap energy loss. Extensive calculations were undertaken to calibrate the two new energy loss mechanisms across all explosives. The corrected Gurney equation is recommended for cylinder use over the original 1943 form. The effect of these corrections is to add more energy to the adiabat values from a relative volume of 2 to 7, with low energy explosives having the largest correction. The data was pushed up to a relative volume of about 15 and the JWL parameter ω was obtained directly. Finally, the total detonation energy density was locked to the v = 7 adiabat energy density, so that the Cylinder test gives all necessary values needed to make a JWL.

  8. Using Auroral Asymmetries to Test MHD Models

    NASA Astrophysics Data System (ADS)

    Reiff, P. H.; Longley, W. J.; Ostgaard, N.; Reistad, J. P.

    2014-12-01

    From 16:40 to 19:00 UT on August 17th, 2001, the IMAGE satellite viewed the Northern aurora, while the POLAR satellite simultaneously observed the Southern aurora. Unlike typical cases where the aurora is nearly conjugate, the Y-component of Interplanetary Magnetic Field (IMF By) during this storm ranged from +20 to +32 nT, causing the polar cap to shift towards the dusk in the Southern hemisphere and towards the dawn in the Northern. Using satellite images in the 130 nm to 160 nm wavelength range, we have been able to identify the polar cap boundary in both hemispheres throughout the event, and calculated the Dawn-Dusk Offset, ∆L, which ranged from 0° to 15° latitude. We then found correlations of 0.90 in the Northern Hemisphere and 0.83 in the Southern Hemisphere between ∆L and IMF By. ∆L also correlated well against IMF Clock Angle (ϴC) and the Epsilon parameter (ɛ = vB2sin[ϴC/2]) when using specific time averages of these parameters. The same methods are then applied to compute the polar cap boundaries in the BATSRUS, OpenGGCM, and LFM-MIX models that were run to simulate the event. We find that none of the models accurately describe the observed open-closed field line boundary during this event, with BATSRUS producing boundaries that are too ideal and symmetric, whereas OpenGGCM and LFM-MIX produced boundaries that are highly distorted and random. The LFM-MIX model gave the best average offset but did not match the observed variation with solar wind parameters.

  9. Multicomponent Equilibrium Models for Testing Geothermometry Approaches

    SciTech Connect

    Cooper, D. Craig; Palmer, Carl D.; Smith, Robert W.; McLing, Travis L.

    2013-02-01

    Geothermometry is an important tool for estimating deep reservoir temperature from the geochemical composition of shallower and cooler waters. The underlying assumption of geothermometry is that the waters collected from shallow wells and seeps maintain a chemical signature that reflects equilibrium in the deeper reservoir. Many of the geothermometers used in practice are based on correlation between water temperatures and composition or using thermodynamic calculations based a subset (typically silica, cations or cation ratios) of the dissolved constituents. An alternative approach is to use complete water compositions and equilibrium geochemical modeling to calculate the degree of disequilibrium (saturation index) for large number of potential reservoir minerals as a function of temperature. We have constructed several “forward” geochemical models using The Geochemist’s Workbench to simulate the change in chemical composition of reservoir fluids as they migrate toward the surface. These models explicitly account for the formation (mass and composition) of a steam phase and equilibrium partitioning of volatile components (e.g., CO2, H2S, and H2) into the steam as a result of pressure decreases associated with upward fluid migration from depth. We use the synthetic data generated from these simulations to determine the advantages and limitations of various geothermometry and optimization approaches for estimating the likely conditions (e.g., temperature, pCO2) to which the water was exposed in the deep subsurface. We demonstrate the magnitude of errors that can result from boiling, loss of volatiles, and analytical error from sampling and instrumental analysis. The estimated reservoir temperatures for these scenarios are also compared to conventional geothermometers. These results can help improve estimation of geothermal resource temperature during exploration and early development.

  10. Petroleum reservoir data for testing simulation models

    SciTech Connect

    Lloyd, J.M.; Harrison, W.

    1980-09-01

    This report consists of reservoir pressure and production data for 25 petroleum reservoirs. Included are 5 data sets for single-phase (liquid) reservoirs, 1 data set for a single-phase (liquid) reservoir with pressure maintenance, 13 data sets for two-phase (liquid/gas) reservoirs and 6 for two-phase reservoirs with pressure maintenance. Also given are ancillary data for each reservoir that could be of value in the development and validation of simulation models. A bibliography is included that lists the publications from which the data were obtained.

  11. A Space Radiation Test Model Study

    DTIC Science & Technology

    1989-02-17

    approxiniationis fi iso - the course of the ssork. tit, other criterion was applied to the latirig the dominant contributions to the right-hand side of...these Iso end gics (t 17, ; .i rli rlc population ire assUrnd sufficietitv issues, at discussion oif eachi is necessary at the outset high rhir i7...Lopez, J. Geophys. Res., 92, 13485 , 1987. B-16 GEOPHYSICAL RESEARCH LETTERS, VOL. 14, NO. 11, PACES 1166-1169, NDVEM13ER 1981 A NONLINEAR MODEL OF WAVE

  12. Steel Containment Vessel Model Test: Results and Evaluation

    SciTech Connect

    Costello, J.F.; Hashimote, T.; Hessheimer, M.F.; Luk, V.K.

    1999-03-01

    A high pressure test of the steel containment vessel (SCV) model was conducted on December 11-12, 1996 at Sandia National Laboratories, Albuquerque, NM, USA. The test model is a mixed-scaled model (1:10 in geometry and 1:4 in shell thickness) of an improved Mark II boiling water reactor (BWR) containment. A concentric steel contact structure (CS), installed over the SCV model and separated at a nominally uniform distance from it, provided a simplified representation of a reactor shield building in the actual plant. The SCV model and contact structure were instrumented with strain gages and displacement transducers to record the deformation behavior of the SCV model during the high pressure test. This paper summarizes the conduct and the results of the high pressure test and discusses the posttest metallurgical evaluation results on specimens removed from the SCV model.

  13. A cautionary note on testing latent variable models

    PubMed Central

    Ropovik, Ivan

    2015-01-01

    The article tackles the practice of testing latent variable models. The analysis covered recently published studies from 11 psychology journals varying in orientation and impact. Seventy-five studies that matched the criterion of applying some of the latent modeling techniques were reviewed. Results indicate the presence of a general tendency to ignore the model test (χ2) followed by the acceptance of approximate fit hypothesis without detailed model examination yielding relevant empirical evidence. Due to reduced sensitivity of such a procedure to confront theory with data, there is an almost invariable tendency to accept the theoretical model. This absence of model test consequences, manifested in frequently unsubstantiated neglect of evidence speaking against the model, thus implies the perilous question of whether such empirical testing of latent structures (the way it is widely applied) makes sense at all. PMID:26594192

  14. Arrhythmogenic Right Ventricular Cardiomyopathy - 4 Swedish families with an associated PKP2 c.2146-1G>C variant

    PubMed Central

    Svensson, Anneli; Åström-Aneq, Meriam; Widlund, Kjerstin Ferm; Fluur, Christina; Green, Anna; Rehnberg, Malin; Gunnarsson, Cecilia

    2016-01-01

    In this study, the genotype-phenotype correlations in four unrelated families with a PKP2 c.2146-1G>C gene variant were studied. Our primary aim was to determine the carriers that fulfilled the arrhythmogenic right ventricular cardiomyopathy (ARVC) diagnostic criteria of 2010. Our secondary aim was to investigate whether any specific clinical characteristics can be attributed to this particular gene variant. Index patients were assessed using next generation ARVC panel sequencing technique and their family members were assessed by Sanger sequencing targeted at the PKP2 c.2146-1G>C variant. The gene variant carriers were offered a clinical follow-up, with evaluation based on the patient’s history and a standard set of non-invasive testing. The PKP2 c.2146-1G>C gene variant was found in 23 of 41 patients who underwent the examination. Twelve of the 19 family members showed “possible ARVC”. One with “borderline ARVC” and the rest with “definite ARVC” demonstrated re-polarization disturbances, but arrhythmia was uncommon. A lethal event occurred in a 14-year-old boy. In the present study, no definitive genotype-phenotype correlations were found, where the majority of the family members carrying the PKP2 c.2146-1G>C gene variant were diagnosed with “possible ARVC”. These individuals should be offered a long-term follow-up since they are frequently symptomless but still at risk for insidious sudden cardiac death due to ventricular arrhythmia. PMID:27335691

  15. Marker vaccine potential of a foot-and-mouth disease virus with a partial VP1 G-H loop deletion.

    PubMed

    Fowler, V L; Knowles, N J; Paton, D J; Barnett, P V

    2010-04-26

    Previous work in cattle and pigs demonstrated that protection against foot-and-mouth disease (FMD) could be achieved following vaccination with chimeric foot-and-mouth disease virus (FMDV) vaccines, in which the VP1 G-H loop had been substituted with that from another serotype. This indicated that the VP1 G-H loop may not be essential for the protection of natural hosts against FMDV. If this could be substantiated there would be potential to develop FMD marker vaccines, characterised by the absence of this region. Here, we investigate the serological responses to vaccination with a virus with a partial VP1 G-H loop deletion in order to determine the likelihood of achieving protection and the potential of this virus as a marker vaccine. Inactivated, oil adjuvanted, vaccines, consisting of chemically inactivated virus with or without a partially deleted VP1 G-H loop, were used to immunise cattle. Serum was collected on days 0, 7, 14 and 21 and antibody titres calculated using the virus neutralisation test (VNT) to estimate the likelihood of protection. We predict a good likelihood that cattle vaccinated with a vaccine characterised by a partial VP1 G-H loop would be protected against challenge with the same virus containing the VP1 G-H loop. We also present evidence on the potential of such a construct to act as a marker vaccine, when used in conjunction with a novel serological test.

  16. Applications of the Linear Logistic Test Model in Psychometric Research

    ERIC Educational Resources Information Center

    Kubinger, Klaus D.

    2009-01-01

    The linear logistic test model (LLTM) breaks down the item parameter of the Rasch model as a linear combination of some hypothesized elementary parameters. Although the original purpose of applying the LLTM was primarily to generate test items with specified item difficulty, there are still many other potential applications, which may be of use…

  17. Application of the Rasch Model to Civil Service Testing.

    ERIC Educational Resources Information Center

    Durovic, Jerry

    The New York State Department of Civil Service investigated an empirical application of the Rasch model which appears useful in Civil Service testing. The model is a powerful tool for developing insights into what test items are measuring while permitting the investigator to spot defective items. It also reveals meaningful distinctions in the type…

  18. An Item Response Model for Characterizing Test Compromise.

    ERIC Educational Resources Information Center

    Segall, Daniel O.

    2002-01-01

    Developed an item response model for characterizing test-compromise that enables the estimation of item preview and score-gain distributions. In the approach, models parameters and posterior distributions are estimated by Markov Chain Monte Carlo procedures. Simulation study results suggest that when at least some test items are known to be…

  19. The Development and Testing of a School Improvement Model

    ERIC Educational Resources Information Center

    Leithwood, Kenneth; Jantzi, Doris; McElheron-Hopkins, Charryn

    2006-01-01

    This multimethod study generated and tested a "best evidence" model of school improvement processes (SIP) capable of improving student achievement. Initially developed through the review of a comprehensive body of previous empirical research, the model was further refined through a 2, 5-year longitudinal study in 10 schools. A quantitative test of…

  20. Locally Dependent Linear Logistic Test Model with Person Covariates

    ERIC Educational Resources Information Center

    Ip, Edward H.; Smits, Dirk J. M.; De Boeck, Paul

    2009-01-01

    The article proposes a family of item-response models that allow the separate and independent specification of three orthogonal components: item attribute, person covariate, and local item dependence. Special interest lies in extending the linear logistic test model, which is commonly used to measure item attributes, to tests with embedded item…

  1. Applications of the Linear Logistic Test Model in Psychometric Research

    ERIC Educational Resources Information Center

    Kubinger, Klaus D.

    2009-01-01

    The linear logistic test model (LLTM) breaks down the item parameter of the Rasch model as a linear combination of some hypothesized elementary parameters. Although the original purpose of applying the LLTM was primarily to generate test items with specified item difficulty, there are still many other potential applications, which may be of use…

  2. Simple Spreadsheet Models For Interpretation Of Fractured Media Tracer Tests

    EPA Science Inventory

    An analysis of a gas-phase partitioning tracer test conducted through fractured media is discussed within this paper. The analysis employed matching eight simple mathematical models to the experimental data to determine transport parameters. All of the models tested; two porous...

  3. An Evaluation of a Testing Model for Listening Comprehension.

    ERIC Educational Resources Information Center

    Kangli, Ji

    A model for testing listening comprehension in English as a Second Language is discussed and compared with the Test for English Majors (TEM). The model in question incorporates listening for: (1) understanding factual information; (2) comprehension and interpretation; (3) detailed and selective information; (4) global ideas; (5) on-line tasks…

  4. Simple Spreadsheet Models For Interpretation Of Fractured Media Tracer Tests

    EPA Science Inventory

    An analysis of a gas-phase partitioning tracer test conducted through fractured media is discussed within this paper. The analysis employed matching eight simple mathematical models to the experimental data to determine transport parameters. All of the models tested; two porous...

  5. A Test Characteristic Curve Linking Method for the Testlet Model

    ERIC Educational Resources Information Center

    Li, Yanmei; Bolt, Daniel M.; Fu, Jianbin

    2005-01-01

    When tests are made up of testlets, a testlet-based item response theory (IRT) model may be used to account for local dependence among items from a common testlet. This study presents a new test characteristic curve method to link calibrations based on the Bradlow, Wainer, and Wang (1999) testlet model. Procedures for calculating the test…

  6. Classical Ising model test for quantum circuits

    NASA Astrophysics Data System (ADS)

    Geraci, Joseph; Lidar, Daniel A.

    2010-07-01

    We exploit a recently constructed mapping between quantum circuits and graphs in order to prove that circuits corresponding to certain planar graphs can be efficiently simulated classically. The proof uses an expression for the Ising model partition function in terms of quadratically signed weight enumerators (QWGTs), which are polynomials that arise naturally in an expansion of quantum circuits in terms of rotations involving Pauli matrices. We combine this expression with a known efficient classical algorithm for the Ising partition function of any planar graph in the absence of an external magnetic field, and the Robertson-Seymour theorem from graph theory. We give as an example a set of quantum circuits with a small number of non-nearest-neighbor gates which admit an efficient classical simulation.

  7. Boron-10 ABUNCL Models of Fuel Testing

    SciTech Connect

    Siciliano, Edward R.; Lintereur, Azaree T.; Kouzes, Richard T.; Ely, James H.

    2013-10-01

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Coincidence Counting With Boron-Based Alternative Neutron Detection Technology at Pacific Northwest National Laboratory (PNNL) for the development of a 3He proportional counter alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a system based upon 10B-lined proportional tubes in a configuration typical for 3He-based coincidence counter applications. This report provides results from MCNP simulations of the General Electric Reuter-Stokes Alternative Boron-Based Uranium Neutron Coincidence Collar (ABUNCL) active configuration model with fuel pins previously measured at Los Alamos National Laboratory. A comparison of the GE-ABUNCL simulations and simulations of 3He based UNCL-II active counter (the system for which the GE-ABUNCL was targeted to replace) with the same fuel pin assemblies is also provided.

  8. Interferometric tests of Planckian quantum geometry models

    SciTech Connect

    Kwon, Ohkyung; Hogan, Craig J.

    2016-04-19

    The effect of Planck scale quantum geometrical effects on measurements with interferometers is estimated with standard physics, and with a variety of proposed extensions. It is shown that effects are negligible in standard field theory with canonically quantized gravity. Statistical noise levels are estimated in a variety of proposals for nonstandard metric fluctuations, and these alternatives are constrained using upper bounds on stochastic metric fluctuations from LIGO. Idealized models of several interferometer system architectures are used to predict signal noise spectra in a quantum geometry that cannot be described by a fluctuating metric, in which position noise arises from holographic bounds on directional information. Lastly, predictions in this case are shown to be close to current and projected experimental bounds.

  9. Interferometric tests of Planckian quantum geometry models

    SciTech Connect

    Kwon, Ohkyung; Hogan, Craig J.

    2016-04-19

    The effect of Planck scale quantum geometrical effects on measurements with interferometers is estimated with standard physics, and with a variety of proposed extensions. It is shown that effects are negligible in standard field theory with canonically quantized gravity. Statistical noise levels are estimated in a variety of proposals for nonstandard metric fluctuations, and these alternatives are constrained using upper bounds on stochastic metric fluctuations from LIGO. Idealized models of several interferometer system architectures are used to predict signal noise spectra in a quantum geometry that cannot be described by a fluctuating metric, in which position noise arises from holographic bounds on directional information. Lastly, predictions in this case are shown to be close to current and projected experimental bounds.

  10. Interferometric tests of Planckian quantum geometry models

    DOE PAGES

    Kwon, Ohkyung; Hogan, Craig J.

    2016-04-19

    The effect of Planck scale quantum geometrical effects on measurements with interferometers is estimated with standard physics, and with a variety of proposed extensions. It is shown that effects are negligible in standard field theory with canonically quantized gravity. Statistical noise levels are estimated in a variety of proposals for nonstandard metric fluctuations, and these alternatives are constrained using upper bounds on stochastic metric fluctuations from LIGO. Idealized models of several interferometer system architectures are used to predict signal noise spectra in a quantum geometry that cannot be described by a fluctuating metric, in which position noise arises from holographicmore » bounds on directional information. Lastly, predictions in this case are shown to be close to current and projected experimental bounds.« less

  11. Testing Model with "Check Technique" for Physics Education

    ERIC Educational Resources Information Center

    Demir, Cihat

    2016-01-01

    As the number, date and form of the written tests are structured and teacher-oriented, it is considered that it creates fear and anxiety among the students. It has been found necessary and important to form a testing model which will keep the students away from the test anxiety and allows them to learn only about the lesson. For this study,…

  12. Item Response Theory Models for Performance Decline during Testing

    ERIC Educational Resources Information Center

    Jin, Kuan-Yu; Wang, Wen-Chung

    2014-01-01

    Sometimes, test-takers may not be able to attempt all items to the best of their ability (with full effort) due to personal factors (e.g., low motivation) or testing conditions (e.g., time limit), resulting in poor performances on certain items, especially those located toward the end of a test. Standard item response theory (IRT) models fail to…

  13. Tests Of Shear-Flow Model For Acoustic Impedance

    NASA Technical Reports Server (NTRS)

    Parrot, Tony L.; Watson, Willie R.; Jones, Michael G.

    1992-01-01

    Tests described in report conducted to validate two-dimensional shear-flow analytical model for determination of acoustic impedance of acoustic liner in grazing-incidence, grazing-flow environment by use of infinite-waveguide method. Tests successful for both upstream and downstream propagations. Work has potential for utility in testing of engine ducts in commercial aircraft.

  14. Computerized Classification Testing under Practical Constraints with a Polytomous Model.

    ERIC Educational Resources Information Center

    Lau, C. Allen; Wang, Tianyou

    A study was conducted to extend the sequential probability ratio testing (SPRT) procedure with the polytomous model under some practical constraints in computerized classification testing (CCT), such as methods to control item exposure rate, and to study the effects of other variables, including item information algorithms, test difficulties, item…

  15. Item Response Theory Models for Performance Decline during Testing

    ERIC Educational Resources Information Center

    Jin, Kuan-Yu; Wang, Wen-Chung

    2014-01-01

    Sometimes, test-takers may not be able to attempt all items to the best of their ability (with full effort) due to personal factors (e.g., low motivation) or testing conditions (e.g., time limit), resulting in poor performances on certain items, especially those located toward the end of a test. Standard item response theory (IRT) models fail to…

  16. Asteroid phase curve analysis with the H, G 1, G 2 photometric phase function: application to the PTF survey observations

    NASA Astrophysics Data System (ADS)

    Penttilä, Antti; Cellino, Alberto; Lu, Xiaoping; Shevchenko, Vasilij G.; Muinonen, Karri

    2016-10-01

    Estimation of an asteroid's absolute magnitude H from its photometry is extremely important. The absolute magnitude relates the brightness of the asteroid to its size, if the geometric albedo is known. The shape of the phase curve can serve as a proxy for the taxonomic type of the asteroid in cases with no spectral information available [1,2].In 2012, the IAU adopted the H,G1,G2 function to replace the H,G function for phase curve analysis [3]. This new function improves the backscattering behavior of the curve with high- and low-albedo asteroids. The phase function (PF) can be applied to asteroids with multiple high-quality observations. If the number of observations is small, or their accuracy is low, problems may arise. The most apparent problem is that the parameter G or the parameters G1, G2 might be poorly estimated. The solution has been to fix to value of G or values of G1, G2 and estimate only the H. In our recent work [4], we offer a solution that can improve the current situation with the photometric fits with a small number of low-accuracy observations. We present a constrained nonlinear least-squares method for fitting the H,G1,G2 function that can improve the possible bias with low-accuracy data. Then, we revisit the two-parameter PF with new data and offer a new version, the H,G12* PF. Finally, we assess the problem with fixed G or G1, G2 parameters by introducing one-parameter models that relate to five taxonomic asteroid groups. We tie all the models together with three or two parameters, or a single parameter, with a statistical model selection procedure to select the best version for a particular data set.We have developed practical tools for the abovementioned algorithms. We apply the tools to a dataset of 8,900 asteroids with almost 500,000 photometric observations from the Palomar Transient Factory survey [5]. We report the effect of the revised H estimates on the geometric albedos in cases where WISE-mission size estimates are available.[1] D

  17. Reduced folate carrier-1 G80a gene polymorphism is associated with neuroblastoma's development.

    PubMed

    de Miranda, Dyego O; Barros, Jemima E X S; Vieira, Maria Madalena S; Lima, Elker L S; Moraes, Vera L L; da Silva, Helker A; Garcia, Helder L B O; Lima, Cássia A; Gomes, Adriana V; Santos, Neide; Muniz, Maria T C

    2014-08-01

    Neuroblastoma is a malignant embryonal tumor of neural crest cells that give rise to the sympathetic nervous system, responsible for 10-70% of all cases of childhood cancer. Because of its early appearance, it has been suggested that risk factors active in the prenatal can be associated with the pathogenesis of neuroblastoma. The aim of this study was to investigate whether the genetic polymorphisms MTHFR C677T and A1298C, MTR A2756G, TYMS 2R/3R and SLC19A1 G80A, involved in folate metabolism, increase the risk of neuroblastoma in Brazilian children. This study comprised 31 Brazilian children (0-14 years old) diagnosed with neuroblastoma compared with 92 controls. Investigation of polymorphisms MTHFR C677T, MTR A2756G and SLC19A1 A80G was performed using PCR-RFLP, the TYMS 2R/3R using PCR and MTHFR A1298C using AS-PCR. The SLC19A1 A80A genotype was significantly associated with the development of neuroblastoma, compared with the control group (Williams G-Test = 0.0286; OR = 5.1667; 95% CI = 1.4481-18.4338; p = 0.0175). When analyzed together, the 80AG+AA genotypes showed a trend toward association (OR = 3.3033; 95% CI = 1.0586-10.3080; p = 0.0563). Our results suggest that individuals carriers of genotype AA for the SLC19A1 gene present risk for the development of neuroblastoma and possibly have difficulty in absorption of folic acid by the cells, and this may adversely affect the metabolism of folate causing genomic instability and promoting the development of cancer. This is the first retrospective/prospective study to examine the relationship between polymorphisms of folate pathway genes and risk of neuroblastoma.

  18. Development of the GPM Observatory Thermal Vacuum Test Model

    NASA Technical Reports Server (NTRS)

    Yang, Kan; Peabody, Hume

    2012-01-01

    A software-based thermal modeling process was documented for generating the thermal panel settings necessary to simulate worst-case on-orbit flight environments in an observatory-level thermal vacuum test setup. The method for creating such a thermal model involved four major steps: (1) determining the major thermal zones for test as indicated by the major dissipating components on the spacecraft, then mapping the major heat flows between these components; (2) finding the flight equivalent sink temperatures for these test thermal zones; (3) determining the thermal test ground support equipment (GSE) design and initial thermal panel settings based on the equivalent sink temperatures; and (4) adjusting the panel settings in the test model to match heat flows and temperatures with the flight model. The observatory test thermal model developed from this process allows quick predictions of the performance of the thermal vacuum test design. In this work, the method described above was applied to the Global Precipitation Measurement (GPM) core observatory spacecraft, a joint project between NASA and the Japanese Aerospace Exploration Agency (JAXA) which is currently being integrated at NASA Goddard Space Flight Center for launch in Early 2014. From preliminary results, the thermal test model generated from this process shows that the heat flows and temperatures match fairly well with the flight thermal model, indicating that the test model can simulate fairly accurately the conditions on-orbit. However, further analysis is needed to determine the best test configuration possible to validate the GPM thermal design before the start of environmental testing later this year. Also, while this analysis method has been applied solely to GPM, it should be emphasized that the same process can be applied to any mission to develop an effective test setup and panel settings which accurately simulate on-orbit thermal environments.

  19. Tests for Regression Parameters in Power Transformation Models.

    DTIC Science & Technology

    1980-01-01

    of estimating the correct %.JI.J scale and then performing the usual linear model F-test in this estimated Ascale. We explore situations in which this...transformation model. In this model, a simple test consists of estimating the correct scale and t ihv. performin g the usutal l iiear model F-test in ’ this...X (yi,y ) will be the least squares estimaites in the estimated scale X and -(yiY2) will be the least squares estimates calculated in the true but

  20. Implications for Damage Recognition during Dpo4-Mediated Mutagenic Bypass of m1G and m3C Lesions

    SciTech Connect

    Rechkoblit, Olga; Delaney, James C.; Essigmann, John M.; Patel, Dinshaw J.

    2012-05-08

    DNA is susceptible to alkylation damage by a number of environmental agents that modify the Watson-Crick edge of the bases. Such lesions, if not repaired, may be bypassed by Y-family DNA polymerases. The bypass polymerase Dpo4 is strongly inhibited by 1-methylguanine (m1G) and 3-methylcytosine (m3C), with nucleotide incorporation opposite these lesions being predominantly mutagenic. Further, extension after insertion of both correct and incorrect bases, introduces additional base substitution and deletion errors. Crystal structures of the Dpo4 ternary extension complexes with correct and mismatched 3'-terminal primer bases opposite the lesions reveal that both m1G and m3C remain positioned within the DNA template/primer helix. However, both correct and incorrect pairing partners exhibit pronounced primer terminal nucleotide distortion, being primarily evicted from the DNA helix when opposite m1G or misaligned when pairing with m3C. Our studies provide insights into mechanisms related to hindered and mutagenic bypass of methylated lesions and models associated with damage recognition by repair demethylases.

  1. Glide back booster wind tunnel model testing

    NASA Astrophysics Data System (ADS)

    Pricop, M. V.; Cojocaru, M. G.; Stoica, C. I.; Niculescu, M. L.; Neculaescu, A. M.; Persinaru, A. G.; Boscoianu, M.

    2017-07-01

    Affordable space access requires partial or ideally full launch vehicle reuse, which is in line with clean environment requirement. Although the idea is old, the practical use is difficult, requiring very large technology investment for qualification. Rocket gliders like Space Shuttle have been successfullyoperated but the price and correspondingly the energy footprint were found not sustainable. For medium launchers, finally there is a very promising platform as Falcon 9. For very small launchers the situation is more complex, because the performance index (payload to start mass) is already small, versus medium and heavy launchers. For partial reusable micro launchers this index is even smaller. However the challenge has to be taken because it is likely that in a multiyear effort, technology is going to enable the performance recovery to make such a system economically and environmentally feasible. The current paper is devoted to a small unitary glide back booster which is foreseen to be assembled in a number of possible configurations. Although the level of analysis is not deep, the solution is analyzed from the aerodynamic point of view. A wind tunnel model is designed, with an active canard, to enablea more efficient wind tunnel campaign, as a national level premiere.

  2. Economic contract theory tests models of mutualism.

    PubMed

    Weyl, E Glen; Frederickson, Megan E; Yu, Douglas W; Pierce, Naomi E

    2010-09-07

    Although mutualisms are common in all ecological communities and have played key roles in the diversification of life, our current understanding of the evolution of cooperation applies mostly to social behavior within a species. A central question is whether mutualisms persist because hosts have evolved costly punishment of cheaters. Here, we use the economic theory of employment contracts to formulate and distinguish between two mechanisms that have been proposed to prevent cheating in host-symbiont mutualisms, partner fidelity feedback (PFF) and host sanctions (HS). Under PFF, positive feedback between host fitness and symbiont fitness is sufficient to prevent cheating; in contrast, HS posits the necessity of costly punishment to maintain mutualism. A coevolutionary model of mutualism finds that HS are unlikely to evolve de novo, and published data on legume-rhizobia and yucca-moth mutualisms are consistent with PFF and not with HS. Thus, in systems considered to be textbook cases of HS, we find poor support for the theory that hosts have evolved to punish cheating symbionts; instead, we show that even horizontally transmitted mutualisms can be stabilized via PFF. PFF theory may place previously underappreciated constraints on the evolution of mutualism and explain why punishment is far from ubiquitous in nature.

  3. Economic contract theory tests models of mutualism

    PubMed Central

    Weyl, E. Glen; Frederickson, Megan E.; Yu, Douglas W.; Pierce, Naomi E.

    2010-01-01

    Although mutualisms are common in all ecological communities and have played key roles in the diversification of life, our current understanding of the evolution of cooperation applies mostly to social behavior within a species. A central question is whether mutualisms persist because hosts have evolved costly punishment of cheaters. Here, we use the economic theory of employment contracts to formulate and distinguish between two mechanisms that have been proposed to prevent cheating in host–symbiont mutualisms, partner fidelity feedback (PFF) and host sanctions (HS). Under PFF, positive feedback between host fitness and symbiont fitness is sufficient to prevent cheating; in contrast, HS posits the necessity of costly punishment to maintain mutualism. A coevolutionary model of mutualism finds that HS are unlikely to evolve de novo, and published data on legume–rhizobia and yucca–moth mutualisms are consistent with PFF and not with HS. Thus, in systems considered to be textbook cases of HS, we find poor support for the theory that hosts have evolved to punish cheating symbionts; instead, we show that even horizontally transmitted mutualisms can be stabilized via PFF. PFF theory may place previously underappreciated constraints on the evolution of mutualism and explain why punishment is far from ubiquitous in nature. PMID:20733067

  4. Testing a Military Family Stress Model.

    PubMed

    Gewirtz, Abigail H; DeGarmo, David S; Zamir, Osnat

    2017-03-15

    The current study examines a military family stress model, evaluating associations between deployment-related stressors (i.e., deployment length/number, posttraumatic stress disorder [PTSD] symptoms) and parent, child, parenting, and dyadic adjustment among families in which a parent had previously deployed to Iraq or Afghanistan in the recent conflicts. Married families (N = 293) with at least one child between the ages of 4 and 12 were recruited from a Midwestern state. Service members were from the Reserve Component (National Guard or Reserves); fathers (N = 253) and/or mothers had deployed (N = 45) to the recent conflicts in the Middle East. Multiple-method (observations of parenting and couple interactions; questionnaires) and multiple informant measures were gathered online and in the homes of participants, from parents, children, and teachers. Findings demonstrated associations between mothers' and fathers' PTSD symptoms and a latent variable of child adjustment comprising teacher, parent, and child report. Mothers' but not fathers' PTSD symptoms were also associated with dyadic adjustment and parenting practices; parenting practices were in turn associated with child adjustment. The results are discussed in terms of their implications for military family stress research and interventions to support and strengthen parents and families after deployment.

  5. Proper selection of 1 g controls in simulated microgravity research as illustrated with clinorotated plant cell suspension cultures.

    PubMed

    Kamal, Khaled Y; Hemmersbach, Ruth; Medina, F Javier; Herranz, Raúl

    2015-04-01

    Understanding the physical and biological effects of the absence of gravity is necessary to conduct operations on space environments. It has been previously shown that the microgravity environment induces the dissociation of cell proliferation from cell growth in young seedling root meristems, but this source material is limited to few cells in each row of meristematic layers. Plant cell cultures, composed by a large and homogeneous population of proliferating cells, are an ideal model to study the effects of altered gravity on cellular mechanisms regulating cell proliferation and associated cell growth. Cell suspension cultures of Arabidopsis thaliana cell line (MM2d) were exposed to 2D-clinorotation in a pipette clinostat for 3.5 or 14 h, respectively, and were then processed either by quick freezing, to be used in flow cytometry, or by chemical fixation, for microscopy techniques. After long-term clinorotation, the proportion of cells in G1 phase was increased and the nucleolus area, as revealed by immunofluorescence staining with anti-nucleolin, was decreased. Despite the compatibility of these results with those obtained in real microgravity on seedling meristems, we provide a technical discussion in the context of clinorotation and proper 1 g controls with respect to suspension cultures. Standard 1 g procedure of sustaining the cell suspension is achieved by continuously shaking. Thus, we compare the mechanical forces acting on cells in clinorotated samples, in a control static sample and in the standard 1 g conditions of suspension cultures in order to define the conditions of a complete and reliable experiment in simulated microgravity with corresponding 1 g controls. Copyright © 2015 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

  6. Proper selection of 1 g controls in simulated microgravity research as illustrated with clinorotated plant cell suspension cultures

    NASA Astrophysics Data System (ADS)

    Kamal, Khaled Y.; Hemmersbach, Ruth; Medina, F. Javier; Herranz, Raúl

    2015-04-01

    Understanding the physical and biological effects of the absence of gravity is necessary to conduct operations on space environments. It has been previously shown that the microgravity environment induces the dissociation of cell proliferation from cell growth in young seedling root meristems, but this source material is limited to few cells in each row of meristematic layers. Plant cell cultures, composed by a large and homogeneous population of proliferating cells, are an ideal model to study the effects of altered gravity on cellular mechanisms regulating cell proliferation and associated cell growth. Cell suspension cultures of Arabidopsis thaliana cell line (MM2d) were exposed to 2D-clinorotation in a pipette clinostat for 3.5 or 14 h, respectively, and were then processed either by quick freezing, to be used in flow cytometry, or by chemical fixation, for microscopy techniques. After long-term clinorotation, the proportion of cells in G1 phase was increased and the nucleolus area, as revealed by immunofluorescence staining with anti-nucleolin, was decreased. Despite the compatibility of these results with those obtained in real microgravity on seedling meristems, we provide a technical discussion in the context of clinorotation and proper 1 g controls with respect to suspension cultures. Standard 1 g procedure of sustaining the cell suspension is achieved by continuously shaking. Thus, we compare the mechanical forces acting on cells in clinorotated samples, in a control static sample and in the standard 1 g conditions of suspension cultures in order to define the conditions of a complete and reliable experiment in simulated microgravity with corresponding 1 g controls.

  7. A robust model-based test planning procedure

    NASA Astrophysics Data System (ADS)

    Vinot, P.; Cogan, S.; Cipolla, V.

    2005-12-01

    A wide variety of model-based optimal test design methodologies have been developed in the past decade using deterministic approaches. This means that the test planning is based on a single-nominal model and an optimal design is obtained for precisely this model. Needless to say, the deterministic approach can lead to an ineffective distribution of sensors and poorly defined excitation points due to the presence of epistemic modelling errors. In this article, a robust-satisficing design approach to test planning is proposed based on info-gap decision theory. This methodology provides a decision-making tool for better understanding the trade-off between an optimal test design with no robustness to modelling uncertainties and a sub-optimal design which satisfies a less demanding level of performance while remaining maximally robust with respect to a given horizon of info-gap model uncertainty. The proposed strategy is illustrated using an aerospace application under base excitation conditions.

  8. Test plan for hydrologic modeling of protective barriers

    SciTech Connect

    Fayer, M.J.

    1990-03-01

    Pacific Northwest Laboratory prepared this test plan for the Model Applications and Validation Task of the Hanford Protective Barriers Program, which is managed by Westinghouse Hanford Company. The objectives of this plan are to outline the conceptual hydrologic model of protective barriers, discuss the available computer codes, describe the interrelationships between the modeling task and the other tasks of the Protective Barriers Program, present the barrier modeling tests, and estimate the schedule and costs of the hydrologic modeling task for planning purposes by the Protective Barriers Program. The purpose of the tests is to validate models that will be used to confirm the long-term performance of the barrier in minimizing drainage. A second purpose of the tests is to provide information to other parts of the Protective Barriers Program that require such information. 26 refs., 2 figs., 3 tabs.

  9. Bankruptcy risk model and empirical tests.

    PubMed

    Podobnik, Boris; Horvatic, Davor; Petersen, Alexander M; Urosevic, Branko; Stanley, H Eugene

    2010-10-26

    We analyze the size dependence and temporal stability of firm bankruptcy risk in the US economy by applying Zipf scaling techniques. We focus on a single risk factor--the debt-to-asset ratio R--in order to study the stability of the Zipf distribution of R over time. We find that the Zipf exponent increases during market crashes, implying that firms go bankrupt with larger values of R. Based on the Zipf analysis, we employ Bayes's theorem and relate the conditional probability that a bankrupt firm has a ratio R with the conditional probability of bankruptcy for a firm with a given R value. For 2,737 bankrupt firms, we demonstrate size dependence in assets change during the bankruptcy proceedings. Prepetition firm assets and petition firm assets follow Zipf distributions but with different exponents, meaning that firms with smaller assets adjust their assets more than firms with larger assets during the bankruptcy process. We compare bankrupt firms with nonbankrupt firms by analyzing the assets and liabilities of two large subsets of the US economy: 2,545 Nasdaq members and 1,680 New York Stock Exchange (NYSE) members. We find that both assets and liabilities follow a Pareto distribution. The finding is not a trivial consequence of the Zipf scaling relationship of firm size quantified by employees--although the market capitalization of Nasdaq stocks follows a Pareto distribution, the same distribution does not describe NYSE stocks. We propose a coupled Simon model that simultaneously evolves both assets and debt with the possibility of bankruptcy, and we also consider the possibility of firm mergers.

  10. Bankruptcy risk model and empirical tests

    PubMed Central

    Podobnik, Boris; Horvatic, Davor; Petersen, Alexander M.; Urošević, Branko; Stanley, H. Eugene

    2010-01-01

    We analyze the size dependence and temporal stability of firm bankruptcy risk in the US economy by applying Zipf scaling techniques. We focus on a single risk factor—the debt-to-asset ratio R—in order to study the stability of the Zipf distribution of R over time. We find that the Zipf exponent increases during market crashes, implying that firms go bankrupt with larger values of R. Based on the Zipf analysis, we employ Bayes’s theorem and relate the conditional probability that a bankrupt firm has a ratio R with the conditional probability of bankruptcy for a firm with a given R value. For 2,737 bankrupt firms, we demonstrate size dependence in assets change during the bankruptcy proceedings. Prepetition firm assets and petition firm assets follow Zipf distributions but with different exponents, meaning that firms with smaller assets adjust their assets more than firms with larger assets during the bankruptcy process. We compare bankrupt firms with nonbankrupt firms by analyzing the assets and liabilities of two large subsets of the US economy: 2,545 Nasdaq members and 1,680 New York Stock Exchange (NYSE) members. We find that both assets and liabilities follow a Pareto distribution. The finding is not a trivial consequence of the Zipf scaling relationship of firm size quantified by employees—although the market capitalization of Nasdaq stocks follows a Pareto distribution, the same distribution does not describe NYSE stocks. We propose a coupled Simon model that simultaneously evolves both assets and debt with the possibility of bankruptcy, and we also consider the possibility of firm mergers. PMID:20937903

  11. DKIST enclosure modeling and verification during factory assembly and testing

    NASA Astrophysics Data System (ADS)

    Larrakoetxea, Ibon; McBride, William; Marshall, Heather K.; Murga, Gaizka

    2014-08-01

    The Daniel K. Inouye Solar Telescope (DKIST, formerly the Advanced Technology Solar Telescope, ATST) is unique as, apart from protecting the telescope and its instrumentation from the weather, it holds the entrance aperture stop and is required to position it with millimeter-level accuracy. The compliance of the Enclosure design with the requirements, as of Final Design Review in January 2012, was supported by mathematical models and other analyses which included structural and mechanical analyses (FEA), control models, ventilation analysis (CFD), thermal models, reliability analysis, etc. During the Enclosure Factory Assembly and Testing the compliance with the requirements has been verified using the real hardware and the models created during the design phase have been revisited. The tests performed during shutter mechanism subsystem (crawler test stand) functional and endurance testing (completed summer 2013) and two comprehensive system-level factory acceptance testing campaigns (FAT#1 in December 2013 and FAT#2 in March 2014) included functional and performance tests on all mechanisms, off-normal mode tests, mechanism wobble tests, creation of the Enclosure pointing map, control system tests, and vibration tests. The comparison of the assumptions used during the design phase with the properties measured during the test campaign provides an interesting reference for future projects.

  12. A numerical model and spreadsheet interface for pumping test analysis.

    PubMed

    Johnson, G S; Cosgrove, D M; Frederick, D B

    2001-01-01

    Curve-matching techniques have been the standard method of aquifer test analysis for several decades. A variety of techniques provide the capability of evaluating test data from confined, unconfined, leaky aquitard, and other conditions. Each technique, however, is accompanied by a set of assumptions, and evaluation of a combination of conditions can be complicated or impossible due to intractable mathematics or nonuniqueness of the solution. Numerical modeling of pumping tests provides two major advantages: (1) the user can choose which properties to calibrate and what assumptions to make; and (2) in the calibration process the user is gaining insights into the conceptual model of the flow system and uncertainties in the analysis. Routine numerical modeling of pumping tests is now practical due to computer hardware and software advances of the last decade. The RADFLOW model and spreadsheet interface presented in this paper is an easy-to-use numerical model for estimation of aquifer properties from pumping test data. Layered conceptual models and their properties are evaluated in a trial-and-error estimation procedure. The RADFLOW model can treat most combinations of confined, unconfined, leaky aquitard, partial penetration, and borehole storage conditions. RADFLOW is especially useful in stratified aquifer systems with no identifiable lateral boundaries. It has been verified to several analytical solutions and has been applied in the Snake River Plain Aquifer to develop and test conceptual models and provide estimates of aquifer properties. Because the model assumes axially symmetrical flow, it is limited to representing multiple aquifer layers that are laterally continuous.

  13. Selecting Single Model in Combination Forecasting Based on Cointegration Test and Encompassing Test

    PubMed Central

    Jiang, Chuanjin; Zhang, Jing; Song, Fugen

    2014-01-01

    Combination forecasting takes all characters of each single forecasting method into consideration, and combines them to form a composite, which increases forecasting accuracy. The existing researches on combination forecasting select single model randomly, neglecting the internal characters of the forecasting object. After discussing the function of cointegration test and encompassing test in the selection of single model, supplemented by empirical analysis, the paper gives the single model selection guidance: no more than five suitable single models can be selected from many alternative single models for a certain forecasting target, which increases accuracy and stability. PMID:24892061

  14. Selecting single model in combination forecasting based on cointegration test and encompassing test.

    PubMed

    Jiang, Chuanjin; Zhang, Jing; Song, Fugen

    2014-01-01

    Combination forecasting takes all characters of each single forecasting method into consideration, and combines them to form a composite, which increases forecasting accuracy. The existing researches on combination forecasting select single model randomly, neglecting the internal characters of the forecasting object. After discussing the function of cointegration test and encompassing test in the selection of single model, supplemented by empirical analysis, the paper gives the single model selection guidance: no more than five suitable single models can be selected from many alternative single models for a certain forecasting target, which increases accuracy and stability.

  15. Coherent A{sub 1g} and E{sub g} phonons of antimony

    SciTech Connect

    Ishioka, Kunie; Kitajima, Masahiro; Misochko, Oleg V.

    2008-06-15

    We report the ultrafast dynamics of the coherent A{sub 1g} and E{sub g} phonons of antimony as a function of temperature and optical polarization. Like in bismuth, the two phonon modes exhibit nearly {pi}/2 difference in their initial phase, suggesting their different coupling strengths with photoexcited electrons. The dependence of the phonon amplitude on the optical polarization and temperature indicates the generation of the coherent A{sub 1g} phonons through both displacive and Raman processes, rather than a purely displacive one. In contrast, the generation of the coherent E{sub g} phonons can be understood within Raman framework alone.

  16. Dynamic Bandwidth Allocation Algorithm with Fairness in 1G/10G Coexistence EPON System

    NASA Astrophysics Data System (ADS)

    Tanaka, Masaki; Takemoto, Michiya; Takahashi, Akira; Shimokasa, Kiyoshi

    Gigabit Ethernet Passive Optical Networks (GE-PON) systems have been deployed widely as a broadband access solution for the optical access network, the so-called FTTx networks. 10 Gigabit EPON (10G-EPON) is about to be standardizing by a task force (802.3av). To provide the next FTTx solution with 10G-EPON systems, one of the key technologies is how to migrate from 1G-based to 10G-based. In this paper, we present Dynamic Bandwidth Allocation (DBA) algorithm which considered a fair policy for 1G/10G coexistence EPON system to achieve a smooth migration.

  17. Modal test and analysis: Multiple tests concept for improved validation of large space structure mathematical models

    NASA Technical Reports Server (NTRS)

    Wada, B. K.; Kuo, C-P.; Glaser, R. J.

    1986-01-01

    For the structural dynamic analysis of large space structures, the technology in structural synthesis and the development of structural analysis software have increased the capability to predict the dynamic characteristics of the structural system. The various subsystems which comprise the system are represented by various displacement functions; the displacement functions are then combined to represent the total structure. Experience has indicated that even when subsystem mathematical models are verified by test, the mathematical representations of the total system are often in error because the mathematical model of the structural elements which are significant when loads are applied at the interconnection points are not adequately verified by test. A multiple test concept, based upon the Multiple Boundary Condition Test (MBCT), is presented which will increase the accuracy of the system mathematical model by improving the subsystem test and test/analysis correlation procedure.

  18. Outer planet probe engineering model thermal vacuum test

    NASA Technical Reports Server (NTRS)

    Grote, M. G.

    1977-01-01

    A thermal vacuum test was performed on the engineering model of the outer planets atmospheric entry probe. Steady state runs at three simulated radioisotope heating unit loads and one transient run simulating the pre-entry power profile were made to determine the thermal characteristics of the engineering model. An analytic simulation of the model was correlated to the test data. Several steady state and one transient run were made with the model attached to the spacecraft adapter to determine the thermal interface between the model and the adapter.

  19. A Sharing Item Response Theory Model for Computerized Adaptive Testing

    ERIC Educational Resources Information Center

    Segall, Daniel O.

    2004-01-01

    A new sharing item response theory (SIRT) model is presented that explicitly models the effects of sharing item content between informants and test takers. This model is used to construct adaptive item selection and scoring rules that provide increased precision and reduced score gains in instances where sharing occurs. The adaptive item selection…

  20. A Lognormal Model for Response Times on Test Items

    ERIC Educational Resources Information Center

    van der Linden, Wim J.

    2006-01-01

    A lognormal model for the response times of a person on a set of test items is investigated. The model has a parameter structure analogous to the two-parameter logistic response models in item response theory, with a parameter for the speed of each person as well as parameters for the time intensity and discriminating power of each item. It is…

  1. A test of 3 models of Kirtland's warbler habitat suitability

    Treesearch

    Mark D. Nelson; Richard R. Buech

    1996-01-01

    We tested 3 models of Kirtland's warbler (Dendroica kirtlandii) habitat suitability during a period when we believe there was a surplus of good quality breeding habitat. A jack pine canopy-cover model was superior to 2 jack pine stem-density models in predicting Kirtland's warbler habitat use and non-use. Estimated density of birds in high...

  2. Data reduction of room tests for zone model validation

    Treesearch

    M. Janssens; H. C. Tran

    1992-01-01

    Compartment fire zone models are based on many simplifying assumptions, in particular that gases stratify in two distinct layers. Because of these assumptions, certain model output is in a form unsuitable for direct comparison to measurements made in full-scale room tests. The experimental data must first be reduced and transformed to be compatible with the model...

  3. A Lognormal Model for Response Times on Test Items

    ERIC Educational Resources Information Center

    van der Linden, Wim J.

    2006-01-01

    A lognormal model for the response times of a person on a set of test items is investigated. The model has a parameter structure analogous to the two-parameter logistic response models in item response theory, with a parameter for the speed of each person as well as parameters for the time intensity and discriminating power of each item. It is…

  4. Stochastic Models of Quality Control on Test Misgrading.

    ERIC Educational Resources Information Center

    Wang, Jianjun

    Stochastic models are developed in this article to examine the rate of test misgrading in educational and psychological measurement. The estimation of inadvertent grading errors can serve as a basis for quality control in measurement. Limitations of traditional Poisson models have been reviewed to highlight the need to introduce new models using…

  5. Thermophysical Property Measurements of Molten Semiconductors in 1-g and Reduced-g Condition

    NASA Technical Reports Server (NTRS)

    Rhim, Won-Kyu

    1999-01-01

    , these dispersed impurities in the melts tend to substantially modify the properties of pure semiconductors. Sample levitation done in a vacuum clearly helps maintain the sample purity. However, in the 1-g environment, all gravity caused effects such as convection, sedimentation and buoyancy are still present in the sample. In addition, large forces needed to levitate a sample in the presence of the gravity can cause additional flows in the melt. The use of the High Temperature Electrostatic Levitator (HTESL) for the present research is a recent development and little is known about the flows induced by the electrostatic forces. In this ground base program, we will define the limits of HTESL technology as various thermophysical properties of molten semiconductors are measured.

  6. A Test of Maxwell's Z Model Using Inverse Modeling

    NASA Technical Reports Server (NTRS)

    Anderson, J. L. B.; Schultz, P. H.; Heineck, T.

    2003-01-01

    In modeling impact craters a small region of energy and momentum deposition, commonly called a "point source", is often assumed. This assumption implies that an impact is the same as an explosion at some depth below the surface. Maxwell's Z Model, an empirical point-source model derived from explosion cratering, has previously been compared with numerical impact craters with vertical incidence angles, leading to two main inferences. First, the flowfield center of the Z Model must be placed below the target surface in order to replicate numerical impact craters. Second, for vertical impacts, the flow-field center cannot be stationary if the value of Z is held constant; rather, the flow-field center migrates downward as the crater grows. The work presented here evaluates the utility of the Z Model for reproducing both vertical and oblique experimental impact data obtained at the NASA Ames Vertical Gun Range (AVGR). Specifically, ejection angle data obtained through Three-Dimensional Particle Image Velocimetry (3D PIV) are used to constrain the parameters of Maxwell's Z Model, including the value of Z and the depth and position of the flow-field center via inverse modeling.

  7. A Test of Maxwell's Z Model Using Inverse Modeling

    NASA Technical Reports Server (NTRS)

    Anderson, J. L. B.; Schultz, P. H.; Heineck, T.

    2003-01-01

    In modeling impact craters a small region of energy and momentum deposition, commonly called a "point source", is often assumed. This assumption implies that an impact is the same as an explosion at some depth below the surface. Maxwell's Z Model, an empirical point-source model derived from explosion cratering, has previously been compared with numerical impact craters with vertical incidence angles, leading to two main inferences. First, the flowfield center of the Z Model must be placed below the target surface in order to replicate numerical impact craters. Second, for vertical impacts, the flow-field center cannot be stationary if the value of Z is held constant; rather, the flow-field center migrates downward as the crater grows. The work presented here evaluates the utility of the Z Model for reproducing both vertical and oblique experimental impact data obtained at the NASA Ames Vertical Gun Range (AVGR). Specifically, ejection angle data obtained through Three-Dimensional Particle Image Velocimetry (3D PIV) are used to constrain the parameters of Maxwell's Z Model, including the value of Z and the depth and position of the flow-field center via inverse modeling.

  8. Engineering in software testing: statistical testing based on a usage model applied to medical device development.

    PubMed

    Jones, P L; Swain, W T; Trammell, C J

    1999-01-01

    When a population is too large for exhaustive study, as is the case for all possible uses of a software system, a statistically correct sample must be drawn as a basis for inferences about the population. A Markov chain usage model is an engineering formalism that represents the population of possible uses for which a product is to be tested. In statistical testing of software based on a Markov chain usage model, the rich body of analytical results available for Markov chains provides numerous insights that can be used in both product development and test planing. A usage model is based on specifications rather than code, so insights that result from model building can inform product decisions in the early stages of a project when the opportunity to prevent problems is the greatest. Statistical testing based on a usage model provides a sound scientific basis for quantifying the reliability of software.

  9. Early User Test: BISON for Fission Gas Release Modeling

    SciTech Connect

    Johns, Russell C.

    2014-01-28

    As a test to develop an understanding of the capabilities and input of the nuclear fuel performance code BISON, we modeled the fission gas release of the Oconee rod 15309 as there is benchmark data available for comparison. BISON has two fission gas models available, the Forsber-Massih model and the Simple Integrated Fission Gas Release and Swelling [sifgrs] model. Due to time constraints and availability of model parameters [we did not have all of the parameters for the sifgrs model already in hand] we only tested the Forsberg-Massih model. The Oconee rod test has been used in a number of benchmark studies including the integral assessment of FRAPCON 3.4. The Oconee Rod test is a 5-cycle test bundle with an average burnup of 50GWd/MTU. The FRAPCON assessment predicted that Oconee Rod15309 Test case would release 1.25% of all fission gas produced, while experimentally only 0.8% was released at EOL. Other studies using BISON with the sifgrs model have under predicted EOL fission gas release [FGR].

  10. A NASTRAN Vibration Model of the AH-1G Helicopter Airframe. Volume 1

    DTIC Science & Technology

    1974-06-01

    ACCESSION NO 3. RECIPIENT’S CATALOG NUMBER 4. TITLE fand Sub(ltl*> A NASTRAN VIBRATION "lODEL OF TUE AU-IG HELICOPTER AIRFRAME VOLUIE I OF TVJO...Half Drive Snaft (AN 30051) = 1.55 lb - Transmitter Dual Tachometer (AN 3<.Ü54) = 0.80 lb Total Engine Weight = 585.35 ib 4-2

  11. Compensating Gravity Effects in 1-G Small-Scale Structural Modeling

    DTIC Science & Technology

    1988-10-01

    of Scaling Factors . . . . . . . . . . . . . 48 3. Rock . . . . ... . . . . . . . . . . . . . .. . 484. Concrete and Reinforcement. . o o...15 7 Selected Examples of Stress-Strain Relations for Rock . . . 16 8 Attenuation Coefficient Calculated (Reference 31) . . ... 20 9 Interface... ROCKS (REFERENCE 55) . . . . . . . . . . . . . . 49 7 SUMMARY OF TYPICAL SHEAR STRENGTH AND YOUNG’S MODULUS VALUES OF INTACT ROCK (REFERENCE 58 AND 59

  12. A NASTRAN Vibration Model of the AH-1G Helicopter Airframe. Volume 2

    DTIC Science & Technology

    1974-06-01

    8217"’’-«--<N’N’*»’»*0*»0’OO.OflDflO<-00^-’^ •^^^BDITJ’O- t cyff’(rc?i’u’N’N*’N’N’\\if^"wN«M(r«i»<s(rflr ^-# ^ .» -t ^INININ^-IN-^OC DOr>off»(>( ryff #-#*«jooo

  13. A new fit-for-purpose model testing framework: Decision Crash Tests

    NASA Astrophysics Data System (ADS)

    Tolson, Bryan; Craig, James

    2016-04-01

    Decision-makers in water resources are often burdened with selecting appropriate multi-million dollar strategies to mitigate the impacts of climate or land use change. Unfortunately, the suitability of existing hydrologic simulation models to accurately inform decision-making is in doubt because the testing procedures used to evaluate model utility (i.e., model validation) are insufficient. For example, many authors have identified that a good standard framework for model testing called the Klemes Crash Tests (KCTs), which are the classic model validation procedures from Klemeš (1986) that Andréassian et al. (2009) rename as KCTs, have yet to become common practice in hydrology. Furthermore, Andréassian et al. (2009) claim that the progression of hydrological science requires widespread use of KCT and the development of new crash tests. Existing simulation (not forecasting) model testing procedures such as KCTs look backwards (checking for consistency between simulations and past observations) rather than forwards (explicitly assessing if the model is likely to support future decisions). We propose a fundamentally different, forward-looking, decision-oriented hydrologic model testing framework based upon the concept of fit-for-purpose model testing that we call Decision Crash Tests or DCTs. Key DCT elements are i) the model purpose (i.e., decision the model is meant to support) must be identified so that model outputs can be mapped to management decisions ii) the framework evaluates not just the selected hydrologic model but the entire suite of model-building decisions associated with model discretization, calibration etc. The framework is constructed to directly and quantitatively evaluate model suitability. The DCT framework is applied to a model building case study on the Grand River in Ontario, Canada. A hypothetical binary decision scenario is analysed (upgrade or not upgrade the existing flood control structure) under two different sets of model building

  14. Testing and Implementation of Advanced Reynolds Stress Models

    NASA Technical Reports Server (NTRS)

    Speziale, Charles G.

    1997-01-01

    A research program was proposed for the testing and implementation of advanced turbulence models for non-equilibrium turbulent flows of aerodynamic importance that are of interest to NASA. Turbulence models that are being developed in connection with the Office of Naval Research ARI in Non-equilibrium are provided for implementation and testing in aerodynamic flows at NASA Langley Research Center. Close interactions were established with researchers at Nasa Langley RC and refinements to the models were made based on the results of these tests. The models that have been considered include two-equation models with an anisotropic eddy viscosity as well as full second-order closures. Three types of non-equilibrium corrections to the models have been considered in connection with the ARI on Nonequilibrium Turbulence: conducted for ONR.

  15. Model NbTi Helical Solenoid Fabrication and Test Results

    SciTech Connect

    Andreev, N.; Barzi, E.; Chlachidze, G.; Evbota, D.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Makarov, A.; Novitski, I.; Orris, D.F.; Tartaglia, M.A.; /Fermilab

    2011-09-01

    A program to develop model magnets for a helical cooling channel is under way at Fermilab. In the first steps of a planned sequence of magnets, two four-coil helical solenoid models with 300 mm aperture have been fabricated and tested. These two models, HSM01 and HSM02, used insulated NbTi Rutherford cable wound onto stainless steel rings with spliceless transitions between coils. Strip heaters were included for quench protection of each coil, and the coils were epoxy-impregnated after winding inside the support structures. Based on the results of the first model the second model was made using a cable with optimized cross-section, improved winding and epoxy-impregnation procedures, enhanced ground insulation, and included heat exchange tubing for a test of conduction cooling. We report on the results and lessons learned from fabrication and tests of these two models.

  16. Centrifuge model tests of rainfall-induced slope failures for the investigation of the initiation conditions

    NASA Astrophysics Data System (ADS)

    Matziaris, Vasileios; Marshall, Alec; Yu, Hai-Sui

    2015-04-01

    Rainfall-induced landslides are very common natural disasters which cause damage to properties and infrastructure and may result in the loss of human lives. These phenomena often take place in unsaturated soil slopes and are triggered by the saturation of the soil profile, due to rain infiltration, which leads to a loss of shear strength. The aim of this study is to determine rainfall thresholds for the initiation of landslides under different initial conditions. Model tests of rainfall-induced landslides are conducted in the Nottingham Centre for Geomechanics 50g-T geotechnical centrifuge. Initially unsaturated plane-strain slope models made with fine silica sand are prepared at varying densities at 1g and accommodated within a climatic chamber which provides controlled environmental conditions. During the centrifuge flight at 60g, rainfall events of varying intensity and duration are applied to the slope models causing the initiation of slope failure. The impact of soil state properties and rainfall characteristics on the landslide initiation process are discussed. The variation of pore water pressures within the slope before, during and after simulated rainfall events is recorded using miniature pore pressure transducers buried in the soil model. Slope deformation is determined by using a high-speed camera and digital image analysis techniques.

  17. Assessment of Galileo modal test results for mathematical model verification

    NASA Technical Reports Server (NTRS)

    Trubert, M.

    1984-01-01

    The modal test program for the Galileo Spacecraft was completed at the Jet Propulsion Laboratory in the summer of 1983. The multiple sine dwell method was used for the baseline test. The Galileo Spacecraft is a rather complex 2433 kg structure made of a central core on which seven major appendages representing 30 percent of the total mass are attached, resulting in a high modal density structure. The test revealed a strong nonlinearity in several major modes. This nonlinearity discovered in the course of the test necessitated running additional tests at the unusually high response levels of up to about 21 g. The high levels of response were required to obtain a model verification valid at the level of loads for which the spacecraft was designed. Because of the high modal density and the nonlinearity, correlation between the dynamic mathematical model and the test results becomes a difficult task. Significant changes in the pre-test analytical model are necessary to establish confidence in the upgraded analytical model used for the final load verification. This verification, using a test verified model, is required by NASA to fly the Galileo Spacecraft on the Shuttle/Centaur launch vehicle in 1986.

  18. Analysis of posture and eye movement responses to Coriolis stimulation under 1 G and microgravity conditions.

    PubMed

    Sekine, Motoki; Takahashi, Masahiro; Iida, Masahiro

    2009-12-20

    To detect the effect of microgravity on vestibular responses, we conducted Coriolis stimulation experiments at 1 G and μ G. Five men with vision occluded were asked to tilt their head forward while rotating at 100 degrees/sec. Postural changes were recorded by a 3D linear accelerometer, and the distance of upper body movement was derived from recordings of linear acceleration. Eye movements were recorded by a CCD camera. For a second period after commencing head tilt, the upper body moved 10 cm in the direction of inertia input at 1 G, but it moved to the opposite direction at μ G, i.e., 4 cm in the direction of inertia force. Nystagmus peak slow-phase velocity immediately after head tilt and its attenuation process did not differ between 1 G and μ G. The strength of movement sensation and the severity of motion sickness were far weaker at μ G than at 1 G. It was concluded that inertia input is valid to induce postural and sensation responses only when the external reference is given Z axis by gravity. Vestibular ocular response may be maintained at μ G because the head reference is valid even after the external reference becomes arbitrary.

  19. Retrospective tests of hybrid operational earthquake forecasting models for Canterbury

    NASA Astrophysics Data System (ADS)

    Rhoades, D. A.; Liukis, M.; Christophersen, A.; Gerstenberger, M. C.

    2016-01-01

    The Canterbury, New Zealand, earthquake sequence, which began in September 2010, occurred in a region of low crustal deformation and previously low seismicity. Because, the ensuing seismicity in the region is likely to remain above previous levels for many years, a hybrid operational earthquake forecasting model for Canterbury was developed to inform decisions on building standards and urban planning for the rebuilding of Christchurch. The model estimates occurrence probabilities for magnitudes M ≥ 5.0 in the Canterbury region for each of the next 50 yr. It combines two short-term, two medium-term and four long-term forecasting models. The weight accorded to each individual model in the operational hybrid was determined by an expert elicitation process. A retrospective test of the operational hybrid model and of an earlier informally developed hybrid model in the whole New Zealand region has been carried out. The individual and hybrid models were installed in the New Zealand Earthquake Forecast Testing Centre and used to make retrospective annual forecasts of earthquakes with magnitude M > 4.95 from 1986 on, for time-lags up to 25 yr. All models underpredict the number of earthquakes due to an abnormally large number of earthquakes in the testing period since 2008 compared to those in the learning period. However, the operational hybrid model is more informative than any of the individual time-varying models for nearly all time-lags. Its information gain relative to a reference model of least information decreases as the time-lag increases to become zero at a time-lag of about 20 yr. An optimal hybrid model with the same mathematical form as the operational hybrid model was computed for each time-lag from the 26-yr test period. The time-varying component of the optimal hybrid is dominated by the medium-term models for time-lags up to 12 yr and has hardly any impact on the optimal hybrid model for greater time-lags. The optimal hybrid model is considerably more

  20. Magnetic Testing, and Modeling, Simulation and Analysis for Space Applications

    NASA Technical Reports Server (NTRS)

    Boghosian, Mary; Narvaez, Pablo; Herman, Ray

    2012-01-01

    The Aerospace Corporation (Aerospace) and Lockheed Martin Space Systems (LMSS) participated with Jet Propulsion Laboratory (JPL) in the implementation of a magnetic cleanliness program of the NASA/JPL JUNO mission. The magnetic cleanliness program was applied from early flight system development up through system level environmental testing. The JUNO magnetic cleanliness program required setting-up a specialized magnetic test facility at Lockheed Martin Space Systems for testing the flight system and a testing program with facility for testing system parts and subsystems at JPL. The magnetic modeling, simulation and analysis capability was set up and performed by Aerospace to provide qualitative and quantitative magnetic assessments of the magnetic parts, components, and subsystems prior to or in lieu of magnetic tests. Because of the sensitive nature of the fields and particles scientific measurements being conducted by the JUNO space mission to Jupiter, the imposition of stringent magnetic control specifications required a magnetic control program to ensure that the spacecraft's science magnetometers and plasma wave search coil were not magnetically contaminated by flight system magnetic interferences. With Aerospace's magnetic modeling, simulation and analysis and JPL's system modeling and testing approach, and LMSS's test support, the project achieved a cost effective approach to achieving a magnetically clean spacecraft. This paper presents lessons learned from the JUNO magnetic testing approach and Aerospace's modeling, simulation and analysis activities used to solve problems such as remnant magnetization, performance of hard and soft magnetic materials within the targeted space system in applied external magnetic fields.

  1. Magnetic Testing, and Modeling, Simulation and Analysis for Space Applications

    NASA Technical Reports Server (NTRS)

    Boghosian, Mary; Narvaez, Pablo; Herman, Ray

    2012-01-01

    The Aerospace Corporation (Aerospace) and Lockheed Martin Space Systems (LMSS) participated with Jet Propulsion Laboratory (JPL) in the implementation of a magnetic cleanliness program of the NASA/JPL JUNO mission. The magnetic cleanliness program was applied from early flight system development up through system level environmental testing. The JUNO magnetic cleanliness program required setting-up a specialized magnetic test facility at Lockheed Martin Space Systems for testing the flight system and a testing program with facility for testing system parts and subsystems at JPL. The magnetic modeling, simulation and analysis capability was set up and performed by Aerospace to provide qualitative and quantitative magnetic assessments of the magnetic parts, components, and subsystems prior to or in lieu of magnetic tests. Because of the sensitive nature of the fields and particles scientific measurements being conducted by the JUNO space mission to Jupiter, the imposition of stringent magnetic control specifications required a magnetic control program to ensure that the spacecraft's science magnetometers and plasma wave search coil were not magnetically contaminated by flight system magnetic interferences. With Aerospace's magnetic modeling, simulation and analysis and JPL's system modeling and testing approach, and LMSS's test support, the project achieved a cost effective approach to achieving a magnetically clean spacecraft. This paper presents lessons learned from the JUNO magnetic testing approach and Aerospace's modeling, simulation and analysis activities used to solve problems such as remnant magnetization, performance of hard and soft magnetic materials within the targeted space system in applied external magnetic fields.

  2. Calculation of flight vibration levels of the AH-1G helicopter and correlation with existing flight vibration measurements

    NASA Technical Reports Server (NTRS)

    Ditaranto, R. A.; Sankewitsch, V.

    1989-01-01

    Boeing Helicopters, together with other U.S. Helicopter manufacturers, participated in a finite element applications program to give the United States a superior capability to utilize finite element analysis models in support of helicopter airframe design. The program was sponsored by the NASA Langley Research Center. Under this program, an activity was sponsored to evaluate existing analysis methods applicable to calculate coupled rotor-airframe vibrations. The helicopter used in this evaluation was the AH-1G helicopter. The results of the Boeing Helicopters efforts are summarized. The planned analytical procedure is reviewed. Changes to the planned procedure are discussed, and results of the correlation study are presented.

  3. Association between matrix metalloproteinase 1 -1607 1G>2G polymorphism and cancer risk: a meta-analysis including 19706 subjects.

    PubMed

    Han, Guoda; Wei, Zhijiang; Lu, Zhiliang; Cui, Haibin; Bai, Xiyong; Ge, Huai'e; Zhang, Wei

    2014-01-01

    The association between MMP1 -1607 1G>2G polymorphism and cancer risk has been reported, but results remained controversial and ambiguous. To assess the association between MMP1 -1607 1G>2G polymorphism and cancer risk, a meta-analysis was performed. Based on comprehensive searches of the PubMed, Elsevier Science Direct, Excerpta Medica Database (Embase), and Chinese Biomedical Literature Database (CBM), we identified outcome data from all articles estimating the association between MMP1 -1607 1G>2G polymorphism and cancer risk. The pooled odds ratio (OR) with 95% confidence intervals (CIs) were calculated. Thirty-eight studies involving 10178 cases and 9528 controls were included. Overall, significant association between MMP1 -1607 1G>2G polymorphism and cancer susceptibility was observed for additive model (OR = 1.21, 95% CI 1.09-1.35), for codominant model (OR = 1.34, 95% CI 1.10-1.63), for dominant model (OR = 1.17, 95% CI 1.01-1.34), for recessive model (OR = 1.31, 95% CI 1.14-1.52). In the subgroup analysis by ethnicity, the significant association was found among Asians but not among Caucasians. In the subgroup analysis by site of cancer, significant associations were found among lung cancer, colorectal cancer, head and neck cancer and bladder cancer. This meta-analysis demonstrated that the MMP1 -1607 1G>2G polymorphism was significantly associated with cancer risk.

  4. Design driven test patterns for OPC models calibration

    NASA Astrophysics Data System (ADS)

    Al-Imam, Mohamed

    2009-03-01

    In the modern photolithography process for manufacturing integrated circuits, geometry dimensions need to be realized on silicon which are much smaller than the exposure wavelength. Thus Resolution Enhancement Techniques have an indispensable role towards the implementation of a successful technology process node. Finding an appropriate RET recipe, that answers the needs of a certain fabrication process, usually involves intensive computational simulations. These simulations have to reflect how different elements in the lithography process under study will behave. In order to achieve this, accurate models are needed that truly represent the transmission of patterns from mask to silicon. A common practice in calibrating lithography models is to collect data for the dimensions of some test structures created on the exposure mask along with the corresponding dimensions of these test structures on silicon after exposure. This data is used to tune the models for good predictions. The models will be guaranteed to accurately predict the test structures that has been used in its tuning. However, real designs might have a much greater variety of structures that might not have been included in the test structures. This paper explores a method for compiling the test structures to be used in the model calibration process using design layouts as an input. The method relies on reducing structures in the design layout to the essential unique structure from the lithography models point of view, and thus ensuring that the test structures represent what the model would actually have to predict during the simulations.

  5. Pharmacokinetics of a single 1g dose of azithromycin in rectal tissue in men

    PubMed Central

    Rupasinghe, Thusitha W.; Simpson, Julie A.; Vodstrcil, Lenka A.; Fairley, Christopher K.; McConville, Malcolm J.; Hocking, Jane S.

    2017-01-01

    Chlamydia is the most common bacterial sexually transmitted infection among men who have sex with men. Repeat infection following treatment with 1g azithromycin is common and treatment failure of up to 22% has been reported. This study measured the pharmacokinetics of azithromycin in rectal tissue in men following a single 1g dose to assess whether azithromycin reaches the rectal site in adequate concentrations to kill chlamydia. Ten healthy men took a single oral dose of 1g azithromycin and provided nine self-collected swabs and one blood sample over 14 days. Participant demographics, medications, sexual behaviour, treatment side effects, lubricant use and douching practices were recorded with each swab. Drug concentration over time was determined using liquid chromatography–mass spectrometry and total exposure (AUC0-∞) was estimated from the concentration-time profiles. Following 1g of azithromycin, rectal concentrations peaked after a median of 24 hours (median 133mcg/g) and remained above the minimum inhibitory concentration for chlamydia (0.125mcg/mL) for at least 14 days in all men. AUC0-∞ was the highest ever reported in human tissue (13103((mcg/g).hr)). Tissue concentrations were not associated with weight (mg/kg), but data suggest that increased gastric pH could increase azithromycin levels and diarrhoea or use of water-based lubricants could decrease concentrations. High and sustained concentrations of azithromycin were found in rectal tissue following a single 1g dose suggesting that inadequate concentrations are unlikely to cause treatment failure. Factors effecting absorption (pH and diarrhoea) or drug depletion (douching and water-based lubricants) may be more important determinants of concentrations in situ. PMID:28350806

  6. Development and testing of a mouse simulated space flight model

    NASA Technical Reports Server (NTRS)

    Sonnenfeld, Gerald

    1987-01-01

    The development and testing of a mouse model for simulating some aspects of weightlessness that occurs during space flight, and the carrying out of immunological experiments on animals undergoing space flight is examined. The mouse model developed was an antiorthostatic, hypokinetic, hypodynamic suspension model similar to one used with rats. The study was divided into two parts. The first involved determination of which immunological parameters should be observed on animals flown during space flight or studied in the suspension model. The second involved suspending mice and determining which of those immunological parameters were altered by the suspension. Rats that were actually flown in Space Shuttle SL-3 were used to test the hypotheses.

  7. Semi-analytical model for slug test in unconfined aquifers

    NASA Astrophysics Data System (ADS)

    Mishra, P. K.; Alves Silva, L. P.; Malama, B.

    2015-12-01

    We present mathematical model which describes three dimensional flow of water during slug test in saturated and unsaturated zone. Following Mishra and Neuman (2010), we consider four-parameter exponential model to describe soil-water characteristics curves. Furthermore, we represent the effect of oscillatory response in highly conductive aquifers as did Malama et al. (2011), correlating the oscillatory change in head inside of the well with the drawdown in the aquifer. We conclude by comparing developed model with existing models for analyzing slug tests.

  8. Model test of new floating offshore wind turbine platforms

    NASA Astrophysics Data System (ADS)

    Shin, Hyunkyoung; Dam, Pham Thanh; Jung, Kwang Jin; Song, inseob; Rim, Chaewhan; Chung, Taeyoung

    2013-06-01

    This paper presents the model test results of 3 new spar platforms which were developed based on the OC3-Hywind spar to support a 5-MW wind turbine. By changing the shape but keeping both volume and mass of OC3- Hywind spar platform, those platforms were expected to experience different hydrodynamic and hydrostatic loads. The scale models were built with a 1/128 scale ratio. The model tests were carried out in waves, including both rotating rotor effect and mean wind speed. The characteristic motions of the 3 new models were measured; Response Amplitude Operators (RAO) and significant motions were calculated and compared with those of OC3-Hywind.

  9. Approaches to Testing Interaction Effects Using Structural Equation Modeling Methodology.

    ERIC Educational Resources Information Center

    Li, Fuzhong; Harmer, Peter; Duncan, Terry E.; Duncan, Susan C.; Acock, Alan; Boles, Shawn

    1998-01-01

    Reviews a single indicator approach and multiple indicator approaches that simplify testing interaction effects using structural equation modeling. An illustrative application examines the interactive effect of perceptions of competence and perceptions of autonomy on exercise-intrinsic motivation. (SLD)

  10. Functional Testing Protocols for Commercial Building Efficiency Baseline Modeling Software

    SciTech Connect

    Jump, David; Price, Phillip N.; Granderson, Jessica; Sohn, Michael

    2013-09-06

    This document describes procedures for testing and validating proprietary baseline energy modeling software accuracy in predicting energy use over the period of interest, such as a month or a year. The procedures are designed according to the methodology used for public domain baselining software in another LBNL report that was (like the present report) prepared for Pacific Gas and Electric Company: ?Commercial Building Energy Baseline Modeling Software: Performance Metrics and Method Testing with Open Source Models and Implications for Proprietary Software Testing Protocols? (referred to here as the ?Model Analysis Report?). The test procedure focuses on the quality of the software?s predictions rather than on the specific algorithms used to predict energy use. In this way the software vendor is not required to divulge or share proprietary information about how their software works, while enabling stakeholders to assess its performance.

  11. Generalized F test and generalized deviance test in two-way ANOVA models for randomized trials.

    PubMed

    Shen, Juan; He, Xuming

    2014-01-01

    We consider the problem of detecting treatment effects in a randomized trial in the presence of an additional covariate. By reexpressing a two-way analysis of variance (ANOVA) model in a logistic regression framework, we derive generalized F tests and generalized deviance tests, which provide better power in detecting common location-scale changes of treatment outcomes than the classical F test. The null distributions of the test statistics are independent of the nuisance parameters in the models, so the critical values can be easily determined by Monte Carlo methods. We use simulation studies to demonstrate how the proposed tests perform compared with the classical F test. We also use data from a clinical study to illustrate possible savings in sample sizes.

  12. Formulation of consumables management models: Test plan for the mission planning processor working model

    NASA Technical Reports Server (NTRS)

    Connelly, L. C.

    1977-01-01

    The test plan and test procedures to be used in the verification and validation of the software being implemented in the mission planning processor working model program are documented. The mission planning processor is a user oriented tool for consumables management and is part of the total consumables subsystem management concept. An overview of the working model is presented. Execution of the test plan will comprehensively exercise the working model software. An overview of the test plan, including a testing schedule, is presented along with the test plan for the unit, module, and system levels. The criteria used to validate the working model results for each consumables subsystem is discussed.

  13. Predicting Tests Ordered in Hospital Laboratories using Generalized Linear Modeling.

    PubMed

    Leaven, Laquanda T

    2016-01-01

    Laboratory services in healthcare systems play a vital role in inpatient care. Most hospital laboratories are facing the challenge of reducing cost and improving service quality. The author focuses on identifying test order patterns in a laboratory for a large urban hospital. The data collected from this facility consists of all tests ordered over a three-month time frame and contains test orders for approximately 17,500 patients. Poisson and negative binomial regression models are used to determine how well patient characteristics (patient length of stay and the medical units in which patients are placed) will predict the number of tests being ordered. The test order prediction model developed in this study will aid the management and phlebotomists in the hospital laboratory in securing methods to satisfy the test order demand. By implementing the recommendations of this study, hospital laboratories should see significant improvements in phlebotomist productivity and resource utilization, implementation of which could result in cost savings.

  14. Instrumentation and testing of a prestressed concrete containment vessel model

    SciTech Connect

    Hessheimer, M.F.; Pace, D.W.; Klamerus, E.W.

    1997-04-01

    Static overpressurization tests of two scale models of nuclear containment structures - a steel containment vessel (SCV) representative of an improved, boiling water reactor (BWR) Mark II design and a prestressed concrete containment vessel (PCCV) for pressurized water reactors (PWR) - are being conducted by Sandia National Laboratories for the Nuclear Power Engineering Corporation of Japan and the U.S. Nuclear Regulatory Commission. This paper discusses plans for instrumentation and testing of the PCCV model. 6 refs., 2 figs., 2 tabs.

  15. Ship Dynamics in the Surf Zone Model Testing

    DTIC Science & Technology

    2008-07-01

    Department Technical Report Ship Dynamics in the Surf Zone Model Testing By Miguel Quintero Faydra Schaffer N SW C C D -C IS D -2 00 8...Dynamics in the Surf Zone Model Testing 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 6. AUTHOR(S) 5e. TASK...NUMBER Miguel Quintero and Faydra Schaffer 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) AND ADDRESS(ES) 8

  16. Modeling Student Test-Taking Motivation in the Context of an Adaptive Achievement Test

    ERIC Educational Resources Information Center

    Wise, Steven L.; Kingsbury, G. Gage

    2016-01-01

    This study examined the utility of response time-based analyses in understanding the behavior of unmotivated test takers. For the data from an adaptive achievement test, patterns of observed rapid-guessing behavior and item response accuracy were compared to the behavior expected under several types of models that have been proposed to represent…

  17. On Insensitivity of the Chi-Square Model Test to Nonlinear Misspecification in Structural Equation Models

    ERIC Educational Resources Information Center

    Mooijaart, Ab; Satorra, Albert

    2009-01-01

    In this paper, we show that for some structural equation models (SEM), the classical chi-square goodness-of-fit test is unable to detect the presence of nonlinear terms in the model. As an example, we consider a regression model with latent variables and interactions terms. Not only the model test has zero power against that type of…

  18. On Insensitivity of the Chi-Square Model Test to Nonlinear Misspecification in Structural Equation Models

    ERIC Educational Resources Information Center

    Mooijaart, Ab; Satorra, Albert

    2009-01-01

    In this paper, we show that for some structural equation models (SEM), the classical chi-square goodness-of-fit test is unable to detect the presence of nonlinear terms in the model. As an example, we consider a regression model with latent variables and interactions terms. Not only the model test has zero power against that type of…

  19. Path Analysis Tests of Theoretical Models of Children's Memory Performance

    ERIC Educational Resources Information Center

    DeMarie, Darlene; Miller, Patricia H.; Ferron, John; Cunningham, Walter R.

    2004-01-01

    Path analysis was used to test theoretical models of relations among variables known to predict differences in children's memory--strategies, capacity, and metamemory. Children in kindergarten to fourth grade (chronological ages 5 to 11) performed different memory tasks. Several strategies (i.e., sorting, clustering, rehearsal, and self-testing)…

  20. Linear Model to Assess the Scale's Validity of a Test

    ERIC Educational Resources Information Center

    Tristan, Agustin; Vidal, Rafael

    2007-01-01

    Wright and Stone had proposed three features to assess the quality of the distribution of the items difficulties in a test, on the so called "most probable response map": line, stack and gap. Once a line is accepted as a design model for a test, gaps and stacks are practically eliminated, producing an evidence of the "scale…

  1. 5. Historic photo of scale model of rocket engine test ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. Historic photo of scale model of rocket engine test facility, June 18, 1957. On file at NASA Plumbrook Research Center, Sandusky, Ohio. NASA GRC photo number C-45264. - Rocket Engine Testing Facility, NASA Glenn Research Center, Cleveland, Cuyahoga County, OH

  2. Three Tests of the Learned Helplessness Model of Depression

    ERIC Educational Resources Information Center

    Blaney, Paul H.; Willis, Max H.

    1978-01-01

    Three studies, testing predictions derived from Seligman's helplessness model of depression and generally supported by earlier research, are reported. The first addressed the finding that depressed individuals evidence a perception of noncontingency, the second tested the prediction that undergraduates in whom helplessness had been induced would…

  3. Testing and modeling of PBX-9591 shock initiation

    SciTech Connect

    Lam, Kim; Foley, Timothy; Novak, Alan; Dickson, Peter; Parker, Gary

    2010-01-01

    This paper describes an ongoing effort to develop a detonation sensitivity test for PBX-9501 that is suitable for studying pristine and damaged HE. The approach involves testing and comparing the sensitivities of HE pressed to various densities and those of pre-damaged samples with similar porosities. The ultimate objectives are to understand the response of pre-damaged HE to shock impacts and to develop practical computational models for use in system analysis codes for HE safety studies. Computer simulation with the CTH shock physics code is used to aid the experimental design and analyze the test results. In the calculations, initiation and growth or failure of detonation are modeled with the empirical HVRB model. The historical LANL SSGT and LSGT were reviewed and it was determined that a new, modified gap test be developed to satisfy the current requirements. In the new test, the donor/spacer/acceptor assembly is placed in a holder that is designed to work with fixtures for pre-damaging the acceptor sample. CTH simulations were made of the gap test with PBX-9501 samples pressed to three different densities. The calculated sensitivities were validated by test observations. The agreement between the computed and experimental critical gap thicknesses, ranging from 9 to 21 mm under various test conditions, is well within 1 mm. These results show that the numerical modeling is a valuable complement to the experimental efforts in studying and understanding shock initiation of PBX-9501.

  4. Improving Schools through Inservice Test Construction: The Rossville Model.

    ERIC Educational Resources Information Center

    Gilman, David Alan

    A method for improving curriculum and schools through the local development of competency tests in basic skills--the Competency-Rossville Model (CRM)--is outlined. The method was originated in the school system of Rossville (Illinois) and has been tested in five other midwestern school systems. The approach leads the faculty of the school, with…

  5. Model-Driven Test Generation of Distributed Systems

    NASA Technical Reports Server (NTRS)

    Easwaran, Arvind; Hall, Brendan; Schweiker, Kevin

    2012-01-01

    This report describes a novel test generation technique for distributed systems. Utilizing formal models and formal verification tools, spe cifically the Symbolic Analysis Laboratory (SAL) tool-suite from SRI, we present techniques to generate concurrent test vectors for distrib uted systems. These are initially explored within an informal test validation context and later extended to achieve full MC/DC coverage of the TTEthernet protocol operating within a system-centric context.

  6. Evaluation of a laboratory test model annular momentum control device

    NASA Technical Reports Server (NTRS)

    Groom, N. J.; Terray, D. E.

    1978-01-01

    A 4068 Nm Sec laboratory test model annular momentum control device (AMCD) was described and static and dynamic test results were presented. An AMCD is a spinning annular rim suspended by noncontacting magnetic bearings and powered by a noncontacting linear electromagnetic motor. Test results include spin motor torque characteristics and spin motor and magnetic bearing drag losses. Limitations of some of the design approaches taken was also discussed.

  7. Neurovestibular adaptation in the utricular otolith in fish to hypergravity exposure and re-adaptation to 1G

    NASA Astrophysics Data System (ADS)

    Boyle, R.; Popova, Ye.; Varelas, J.; Mofrad, A.

    after 16-day exposure. Return to control values following 16-day exposure is on the order of 8 days. On-Center Controls (228/s rotation about Earth vertical) at 4-and 16-days do not show any difference compare to ground controls. Utricular sensitivity is strongly regulated by altered gravity exposure, and transition from hypergravity to normal gravity seem to resemble the transfer from 1G to microgravity, and might be used as a ground-based model to study the neural response to transitions in gravity. Preliminary analysis of the afferent distributions changes caused by adaptation to hyper-G and re-adaptation to 1G that uses PDF allows us to assume that hyper-G and G cause the redistribution of afferents with different gains: those with higher gains become more activated (sensitive) than those with lower gains. The case of down-regulation corresponds to decrease of the PDF dispersion. It should be noted that efferent vestibular actions are not uniform on hair cells and afferents, and it is proposed that the changes brought on in otolith afferents by the transitions from one gravity state to another will be most prevalent and coincident in afferents strongly affected by efferent activation. Support Contributed By: NASA 03-OBPR-04

  8. Improved animal models for testing gene therapy for atherosclerosis.

    PubMed

    Du, Liang; Zhang, Jingwan; De Meyer, Guido R Y; Flynn, Rowan; Dichek, David A

    2014-04-01

    Gene therapy delivered to the blood vessel wall could augment current therapies for atherosclerosis, including systemic drug therapy and stenting. However, identification of clinically useful vectors and effective therapeutic transgenes remains at the preclinical stage. Identification of effective vectors and transgenes would be accelerated by availability of animal models that allow practical and expeditious testing of vessel-wall-directed gene therapy. Such models would include humanlike lesions that develop rapidly in vessels that are amenable to efficient gene delivery. Moreover, because human atherosclerosis develops in normal vessels, gene therapy that prevents atherosclerosis is most logically tested in relatively normal arteries. Similarly, gene therapy that causes atherosclerosis regression requires gene delivery to an existing lesion. Here we report development of three new rabbit models for testing vessel-wall-directed gene therapy that either prevents or reverses atherosclerosis. Carotid artery intimal lesions in these new models develop within 2-7 months after initiation of a high-fat diet and are 20-80 times larger than lesions in a model we described previously. Individual models allow generation of lesions that are relatively rich in either macrophages or smooth muscle cells, permitting testing of gene therapy strategies targeted at either cell type. Two of the models include gene delivery to essentially normal arteries and will be useful for identifying strategies that prevent lesion development. The third model generates lesions rapidly in vector-naïve animals and can be used for testing gene therapy that promotes lesion regression. These models are optimized for testing helper-dependent adenovirus (HDAd)-mediated gene therapy; however, they could be easily adapted for testing of other vectors or of different types of molecular therapies, delivered directly to the blood vessel wall. Our data also supports the promise of HDAd to deliver long

  9. Test model designs for advanced refractory ceramic materials

    NASA Technical Reports Server (NTRS)

    Tran, Huy Kim

    1993-01-01

    The next generation of space vehicles will be subjected to severe aerothermal loads and will require an improved thermal protection system (TPS) and other advanced vehicle components. In order to ensure the satisfactory performance system (TPS) and other advanced vehicle materials and components, testing is to be performed in environments similar to space flight. The design and fabrication of the test models should be fairly simple but still accomplish test objectives. In the Advanced Refractory Ceramic Materials test series, the models and model holders will need to withstand the required heat fluxes of 340 to 817 W/sq cm or surface temperatures in the range of 2700 K to 3000 K. The model holders should provide one dimensional (1-D) heat transfer to the samples and the appropriate flow field without compromising the primary test objectives. The optical properties such as the effective emissivity, catalytic efficiency coefficients, thermal properties, and mass loss measurements are also taken into consideration in the design process. Therefore, it is the intent of this paper to demonstrate the design schemes for different models and model holders that would accommodate these test requirements and ensure the safe operation in a typical arc jet facility.

  10. Realistic test cases for limited area ocean modelling

    NASA Astrophysics Data System (ADS)

    Herzfeld, M.; Schmidt, M.; Griffies, S. M.; Liang, Z.

    The applicability of Modular Ocean Model version 4 (MOM4p1) as a code base to study regional physical oceanographic phenomena is presented, highlighting features recently implemented for use in limited area domains. Central to the successful operation of limited area model applications are the inclusion of a comprehensive suite of open boundary conditions, turbulence closure and vertical discretization. The open boundary problem, in particular, is considered and we present the open boundary condition implementation and performance in limited area model configurations corresponding to three realistic test cases. These tests represent typical configurations the physical oceanographer may encounter, and consist of (1) a coastal shelf model application where a two-tiered model configuration is used for down-scaling from a coarse grid model to supply sufficiently resolved boundary values for active cross-shelf open boundaries of a regional model; (2) tidal response of a gulf with one open boundary across the mouth of the gulf; (3) response of a coastal region to the passage of a tropical cyclone, where the open boundaries behave in primarily a passive capacity. Although the code base used in the test cases is MOM4p1, emphasis is placed on general features of the tests that are necessary for the scientific and operational use of any limited area model, hence key findings may be applied to limited area models in general.

  11. Bayesian model evidence for order selection and correlation testing.

    PubMed

    Johnston, Leigh A; Mareels, Iven M Y; Egan, Gary F

    2011-01-01

    Model selection is a critical component of data analysis procedures, and is particularly difficult for small numbers of observations such as is typical of functional MRI datasets. In this paper we derive two Bayesian evidence-based model selection procedures that exploit the existence of an analytic form for the linear Gaussian model class. Firstly, an evidence information criterion is proposed as a model order selection procedure for auto-regressive models, outperforming the commonly employed Akaike and Bayesian information criteria in simulated data. Secondly, an evidence-based method for testing change in linear correlation between datasets is proposed, which is demonstrated to outperform both the traditional statistical test of the null hypothesis of no correlation change and the likelihood ratio test.

  12. A general diagnostic model applied to language testing data.

    PubMed

    von Davier, Matthias

    2008-11-01

    Probabilistic models with one or more latent variables are designed to report on a corresponding number of skills or cognitive attributes. Multidimensional skill profiles offer additional information beyond what a single test score can provide, if the reported skills can be identified and distinguished reliably. Many recent approaches to skill profile models are limited to dichotomous data and have made use of computationally intensive estimation methods such as Markov chain Monte Carlo, since standard maximum likelihood (ML) estimation techniques were deemed infeasible. This paper presents a general diagnostic model (GDM) that can be estimated with standard ML techniques and applies to polytomous response variables as well as to skills with two or more proficiency levels. The paper uses one member of a larger class of diagnostic models, a compensatory diagnostic model for dichotomous and partial credit data. Many well-known models, such as univariate and multivariate versions of the Rasch model and the two-parameter logistic item response theory model, the generalized partial credit model, as well as a variety of skill profile models, are special cases of this GDM. In addition to an introduction to this model, the paper presents a parameter recovery study using simulated data and an application to real data from the field test for TOEFL Internet-based testing.

  13. A Moist Idealized Test Case for Atmospheric General Circulation Models

    NASA Astrophysics Data System (ADS)

    Thatcher, D.; Jablonowski, C.; Zarzycki, C.

    2013-12-01

    The vast array of dynamical and physical processes within atmospheric general circulation models (GCMs) makes it difficult to correctly distinguish the sources of error within a model. Therefore, simplified test cases are important in testing the accuracy of individual model components, such as the fluid flow component in the dynamical core. Typically, dynamical cores are coupled to complex subgrid-scale physical parameterization packages, and the nonlinear interactions mask the causes and effects of atmospheric phenomena. Idealized tests are a computationally efficient method for analyzing the underlying numerical techniques of dynamical cores. The newly proposed test case is based on the widely-used Held and Suarez (1994) (HS) test for dry dynamical cores. The latter replaces the full physical parameterization package with a Newtonian temperature relaxation and Rayleigh damping of low-level winds on a flat planet. However, the impact of moisture, a crucial physics-dynamics coupling process, is missing from the HS test. Here we present a moist variant of the HS test case to create a test case of intermediate complexity with idealized moisture feedbacks. It uses simplified physical processes to model large-scale condensation, boundary layer turbulence, and surface fluxes of horizontal momentum, latent heat, and sensible heat between the atmosphere and an ocean-covered planet (Reed and Jablonowski, 2012). We apply this test to four dynamical cores within NCAR's Community Atmosphere Model version 5.3, including the Finite Volume, Eulerian spectral transform, semi-Lagrangian spectral transform, and Spectral Element dynamical cores. We analyze the kinetic energy spectra, general circulation, and precipitation of this new moist idealized test case across all four dynamical cores. Simulations of the moist idealized test case are compared to aqua-planet experiments with complex physical parameterizations. The moist idealized test case successfully reproduces many features

  14. Testing and reference model analysis of FTTH system

    NASA Astrophysics Data System (ADS)

    Feng, Xiancheng; Cui, Wanlong; Chen, Ying

    2009-08-01

    With rapid development of Internet and broadband access network, the technologies of xDSL, FTTx+LAN , WLAN have more applications, new network service emerges in endless stream, especially the increase of network game, meeting TV, video on demand, etc. FTTH supports all present and future service with enormous bandwidth, including traditional telecommunication service, traditional data service and traditional TV service, and the future digital TV and VOD. With huge bandwidth of FTTH, it wins the final solution of broadband network, becomes the final goal of development of optical access network.. Fiber to the Home (FTTH) will be the goal of telecommunications cable broadband access. In accordance with the development trend of telecommunication services, to enhance the capacity of integrated access network, to achieve triple-play (voice, data, image), based on the existing optical Fiber to the curb (FTTC), Fiber To The Zone (FTTZ), Fiber to the Building (FTTB) user optical cable network, the optical fiber can extend to the FTTH system of end-user by using EPON technology. The article first introduced the basic components of FTTH system; and then explain the reference model and reference point for testing of the FTTH system; Finally, by testing connection diagram, the testing process, expected results, primarily analyze SNI Interface Testing, PON interface testing, Ethernet performance testing, UNI interface testing, Ethernet functional testing, PON functional testing, equipment functional testing, telephone functional testing, operational support capability testing and so on testing of FTTH system. ...

  15. Test Driven Development: Lessons from a Simple Scientific Model

    NASA Astrophysics Data System (ADS)

    Clune, T. L.; Kuo, K.

    2010-12-01

    In the commercial software industry, unit testing frameworks have emerged as a disruptive technology that has permanently altered the process by which software is developed. Unit testing frameworks significantly reduce traditional barriers, both practical and psychological, to creating and executing tests that verify software implementations. A new development paradigm, known as test driven development (TDD), has emerged from unit testing practices, in which low-level tests (i.e. unit tests) are created by developers prior to implementing new pieces of code. Although somewhat counter-intuitive, this approach actually improves developer productivity. In addition to reducing the average time for detecting software defects (bugs), the requirement to provide procedure interfaces that enable testing frequently leads to superior design decisions. Although TDD is widely accepted in many software domains, its applicability to scientific modeling still warrants reasonable skepticism. While the technique is clearly relevant for infrastructure layers of scientific models such as the Earth System Modeling Framework (ESMF), numerical and scientific components pose a number of challenges to TDD that are not often encountered in commercial software. Nonetheless, our experience leads us to believe that the technique has great potential not only for developer productivity, but also as a tool for understanding and documenting the basic scientific assumptions upon which our models are implemented. We will provide a brief introduction to test driven development and then discuss our experience in using TDD to implement a relatively simple numerical model that simulates the growth of snowflakes. Many of the lessons learned are directly applicable to larger scientific models.

  16. Phosphatidylinositol-3 kinase-dependent translational regulation of Id1 involves the PPM1G phosphatase

    PubMed Central

    Xu, Kaiming; Wang, Lanfang; Feng, Wei; Feng, Yue; Shu, Hui-Kuo G.

    2016-01-01

    Id1 is a helix-loop-helix transcriptional modulator that increases the aggressiveness of malignant glial neoplasms. Since most glioblastomas (GBMs) show increased phosphatidylinositol-3 kinase (PI-3K) signaling, we sought to determine whether this pathway regulates Id1 expression. Higher basal Id1 expression correlates with dysregulated PI-3K signaling in multiple established GBM cell lines. Further characterization of PI-3K-dependent Id1 regulation reveals that chemical or genetic inhibition of PI-3K signaling reduces Id1 protein but not mRNA expression. Overall, PI-3K signaling appears to enhance Id1 translation with no significant effect on its stability. PI-3K signaling is known to regulate protein translation through mTORC1-dependent phosphorylation of 4E-BP1, which reduces its association with and inhibition of the translation initiation factor eIF4E. Interestingly, while inhibition of PI-3K and AKT lowers 4E-BP1 phosphorylation and expression of Id1 in all cases, inhibition of TORC1 with rapamycin does not consistently have a similar effect suggesting an alternative mechanism for PI-3K-dependent regulation of Id1 translation. We now identify a potential role for the serine-threonine phosphatase PPM1G in translational regulation of Id1 protein expression. PPM1G knockdown by siRNA increase both 4E-BP1 phosphorylation and Id1 expression and PPM1G and 4E-BP1 co-associates in GBM cells. Furthermore, PPM1G is a phosphoprotein and this phosphorylation appears to be regulated by PI-3K activity. Finally, PI-3K inhibition increases PPM1G activity when assessed by an in vitro phosphatase assay. Our findings provide the first evidence that the PI-3K/AKT signaling pathway modulates PPM1G activity resulting in a shift in the balance between hyper- and hypo-phosphorylated 4E-BP1 and translational regulation of Id1 expression. PMID:27065332

  17. The association between RFC1 G80A polymorphism and cancer susceptibility: Evidence from 33 studies

    PubMed Central

    Huang, Xiaoyi; Gao, Yisha; He, Jing; Cai, Jiao; Ta, Na; Jiang, Hui; Zhu, Jinhong; Zheng, Jianming

    2016-01-01

    Aberrant folate metabolism is closely related to tumorigenesis. Genetic variations in the Reduced folate carrier 1 (RFC1) may alter the progress of folate metabolism, and thereby cause the initiation and progress of the cancer. Considerable studies have performed to investigate the association between RFC1 G80A (rs1051266) polymorphism and cancer susceptibility, but the conclusions were conflicting. Therefore, we conducted a meta-analysis to reevaluate the association of RFC1 G80A polymorphism with cancer risk. PubMed and EMBASE were searched for eligible studies. The association of RFC1 G80A polymorphism and cancer risk was evaluated by the pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs). The significant association was found between RFC1 G80A polymorphism and hematological malignance susceptibility (A vs. G: OR=1.11, 95%CI=1.003-1.23, P=0.045; GA vs. GG: OR=1.18, 95%CI=1.06-1.31, P=0.002; AA+GA vs. GG: OR=1.18, 95%CI=1.07-1.29, P=0.001). Stratified analysis by ethnicity indicated that the association became more prominent among Caucasians (GA vs. GG: OR=1.28, 95%CI=1.12-1.45, P<0.001; AA+GA vs. GG: OR=1.21, 95%CI=1.08-1.36, P=0.001). In term of the cancer type, this polymorphism significantly increased the risk of acute lymphoblast leukemia (GA vs. GG: OR=1.13, 95%CI=1.001-1.28, P=0.048; AA+GA vs. GG: OR=1.28, 95%CI=1.13-1.46, P<0.001) and acute myeloid leukemia (GA vs. GG: OR=2.57, 95%CI=1.37-4.85, P=0.003). No significant association between RFC1 G80A polymorphism and overall solid cancer risk was observed, but a protective association with digestive cancer risk was found (GA vs. GG: OR=0.89, 95%CI= 0.81-0.99, P=0.030). The comprehensive meta-analysis encouraged the notion that RFC1 G80A polymorphism may play an important role in hematopoietic system malignance. These findings need further validation in the large multicenter investigations. PMID:26819637

  18. TASS Model Application for Testing the TDWAP Model

    NASA Technical Reports Server (NTRS)

    Switzer, George F.

    2009-01-01

    One of the operational modes of the Terminal Area Simulation System (TASS) model simulates the three-dimensional interaction of wake vortices within turbulent domains in the presence of thermal stratification. The model allows the investigation of turbulence and stratification on vortex transport and decay. The model simulations for this work all assumed fully-periodic boundary conditions to remove the effects from any surface interaction. During the Base Period of this contract, NWRA completed generation of these datasets but only presented analysis for the neutral stratification runs of that set (Task 3.4.1). Phase 1 work began with the analysis of the remaining stratification datasets, and in the analysis we discovered discrepancies with the vortex time to link predictions. This finding necessitated investigating the source of the anomaly, and we found a problem with the background turbulence. Using the most up to date version TASS with some important defect fixes, we regenerated a larger turbulence domain, and verified the vortex time to link with a few cases before proceeding to regenerate the entire 25 case set (Task 3.4.2). The effort of Phase 2 (Task 3.4.3) concentrated on analysis of several scenarios investigating the effects of closely spaced aircraft. The objective was to quantify the minimum aircraft separations necessary to avoid vortex interactions between neighboring aircraft. The results consist of spreadsheets of wake data and presentation figures prepared for NASA technical exchanges. For these formation cases, NASA carried out the actual TASS simulations and NWRA performed the analysis of the results by making animations, line plots, and other presentation figures. This report contains the description of the work performed during this final phase of the contract, the analysis procedures adopted, and sample plots of the results from the analysis performed.

  19. Testing Mediation in Structural Equation Modeling: The Effectiveness of the Test of Joint Significance

    ERIC Educational Resources Information Center

    Leth-Steensen, Craig; Gallitto, Elena

    2016-01-01

    A large number of approaches have been proposed for estimating and testing the significance of indirect effects in mediation models. In this study, four sets of Monte Carlo simulations involving full latent variable structural equation models were run in order to contrast the effectiveness of the currently popular bias-corrected bootstrapping…

  20. Testing Mediation in Structural Equation Modeling: The Effectiveness of the Test of Joint Significance

    ERIC Educational Resources Information Center

    Leth-Steensen, Craig; Gallitto, Elena

    2016-01-01

    A large number of approaches have been proposed for estimating and testing the significance of indirect effects in mediation models. In this study, four sets of Monte Carlo simulations involving full latent variable structural equation models were run in order to contrast the effectiveness of the currently popular bias-corrected bootstrapping…

  1. Advanced Fuel Cycle Initiative AFC-1D, AFC-1G and AFC-1H End of FY-06 Irradiation Report

    SciTech Connect

    Advanced Fuel Cycle Initiative AFC-1D, AFC-1G and

    2006-09-01

    The U. S. Advanced Fuel Cycle Initiative (AFCI) seeks to develop and demonstrate the technologies needed to transmute the long-lived transuranic actinide isotopes contained in spent nuclear fuel into shorter-lived fission products, thereby dramatically decreasing the volume of material requiring disposition and the long-term radiotoxity and heat load of high-level waste sent to a geologic repository. The AFC-1 irradiation experiments on transmutation fuels are expected to provide irradiation performance data on non-fertile and low-fertile fuel forms specifically, irradiation growth and swelling, helium production, fission gas release, fission product and fuel constituent migration, fuel phase equilibria, and fuel-cladding chemical interaction. Contained in this report are the to-date physics evaluations performed on three of the AFC-1 experiments; AFC-1D, AFC-1G and AFC-1H. The AFC-1D irradiation experiment consists of metallic non-fertile fuel compositions with minor actinides for potential use in accelerator driven systems and AFC-1G and AFC-1H irradiation experiments are part of the fast neutron reactor fuel development effort. The metallic fuel experiments and nitride experiment are high burnup analogs to previously irradiated experiments and are to be irradiated to = 40 at.% burnup and = 25 at.% burnup, respectively. Based on the results of the physics evaluations it has been determined that the AFC-1D experiment will remain in the ATR for approximately 4 additional cycles, the AFC-1G experiment for an additional 4-5 cycles, and the AFC-1H experiment for approximately 8 additional cycles, in order to reach the desired programmatic burnup. The specific irradiation schedule for these tests will be determined based on future physics evaluations and all results will be documented in subsequent reports.

  2. Residual flexibility test method for verification of constrained structural models

    NASA Technical Reports Server (NTRS)

    Admire, John R.; Tinker, Michael L.; Ivey, Edward W.

    1992-01-01

    A method is presented for deriving constrained modes and frequencies from a model correlated to a set of free-free test modes and a set of measured residual flexibilities. The method involves a simple modification of the MacNeal and Rubin component mode representation to allow verification of a constrained structural model. Results for two spaceflight structures show quick convergence of constrained modes using an easily measurable set of free-free modes plus the residual flexibility matrix or its boundary partition. This paper further validates the residual flexibility approach as an alternative test/analysis method when fixed-base testing proves impractical.

  3. Foundation model testing of the second deformation modulus Eν2

    NASA Astrophysics Data System (ADS)

    Sun, Xiao

    2017-09-01

    The bearing capacity of the soil foundation can be reflected by its second deformation modulus Eν2 , and the construction quality of the soil foundation can be evaluated by this deformation modulus. At present, the detection method of Eν2 has been applied in construction quality control of soil foundation in applications such as the foundations of airports, railways, and highways. In order to show the feasibility and reliability of the laboratory test method of calculating Eν2 , the field test method is simulated to test the value of Eν2 of the fill foundation model and compare it with the laboratory test method. The results show that the results of field testing and laboratory testing were in good agreement. This provides a new method for testing the value of Eν2 .

  4. Model validation of the Sandia 34-Meter Test Bed Turbine using substructure modal-testing

    SciTech Connect

    Carne, T.G.; Lauffer, J.P.; Gomez, A.J.; Ashwill, T.D.

    1989-01-01

    The Sandia 34-Meter Test Bed Turbine is a vertical-axis wind turbine, thirty-four meters in diameter, designed to provide a test-bed for research in aerodynamics, structures and control. In order to design a large wind turbine, knowledge of the modal frequencies and mode shapes is essential for predicting structural response. During the design, analytical or finite element models are utilized for estimates of these modal parameters. However, when hardware becomes available, modal testing can be used to verify or update the models. The concept of substructure modal testing was developed for the Sandia 34-Meter Test Bed in order to more fully evaluate the accuracy of the finite element model. Instead of performing only one test on the entire turbine, separate tests and analyses were performed on major substructures of the turbine, including three separate blade sections, the tower supported by the guy cables, and the entire turbine. The results were then compared to analytical predictions from the finite element models of the substructures and the entire turbine. 8 refs., 6 figs., 6 tabs.

  5. Animal models for testing anti-prion drugs.

    PubMed

    Fernández-Borges, Natalia; Elezgarai, Saioa R; Eraña, Hasier; Castilla, Joaquín

    2013-01-01

    Prion diseases belong to a group of fatal infectious diseases with no effective therapies available. Throughout the last 35 years, less than 50 different drugs have been tested in different experimental animal models without hopeful results. An important limitation when searching for new drugs is the existence of appropriate models of the disease. The three different possible origins of prion diseases require the existence of different animal models for testing anti-prion compounds. Wild type, over-expressing transgenic mice and other more sophisticated animal models have been used to evaluate a diversity of compounds which some of them were previously tested in different in vitro experimental models. The complexity of prion diseases will require more pre-screening studies, reliable sporadic (or spontaneous) animal models and accurate chemical modifications of the selected compounds before having an effective therapy against human prion diseases. This review is intended to put on display the more relevant animal models that have been used in the search of new antiprion therapies and describe some possible procedures when handling chemical compounds presumed to have anti-prion activity prior to testing them in animal models.

  6. A Negative Binomial Regression Model for Accuracy Tests

    ERIC Educational Resources Information Center

    Hung, Lai-Fa

    2012-01-01

    Rasch used a Poisson model to analyze errors and speed in reading tests. An important property of the Poisson distribution is that the mean and variance are equal. However, in social science research, it is very common for the variance to be greater than the mean (i.e., the data are overdispersed). This study embeds the Rasch model within an…

  7. Unit-Weighted Scales Imply Models that Should Be Tested!

    ERIC Educational Resources Information Center

    Beauducel, Andre; Leue, Anja

    2013-01-01

    In several studies unit-weighted sum scales based on the unweighted sum of items are derived from the pattern of salient loadings in confirmatory factor analysis. The problem of this procedure is that the unit-weighted sum scales imply a model other than the initially tested confirmatory factor model. In consequence, it remains generally unknown…

  8. A Negative Binomial Regression Model for Accuracy Tests

    ERIC Educational Resources Information Center

    Hung, Lai-Fa

    2012-01-01

    Rasch used a Poisson model to analyze errors and speed in reading tests. An important property of the Poisson distribution is that the mean and variance are equal. However, in social science research, it is very common for the variance to be greater than the mean (i.e., the data are overdispersed). This study embeds the Rasch model within an…

  9. Using fMRI to Test Models of Complex Cognition

    ERIC Educational Resources Information Center

    Anderson, John R.; Carter, Cameron S.; Fincham, Jon M.; Qin, Yulin; Ravizza, Susan M.; Rosenberg-Lee, Miriam

    2008-01-01

    This article investigates the potential of fMRI to test assumptions about different components in models of complex cognitive tasks. If the components of a model can be associated with specific brain regions, one can make predictions for the temporal course of the BOLD response in these regions. An event-locked procedure is described for dealing…

  10. Learning-Testing Process in Classroom: An Empirical Simulation Model

    ERIC Educational Resources Information Center

    Buda, Rodolphe

    2009-01-01

    This paper presents an empirical micro-simulation model of the teaching and the testing process in the classroom (Programs and sample data are available--the actual names of pupils have been hidden). It is a non-econometric micro-simulation model describing informational behaviors of the pupils, based on the observation of the pupils'…

  11. An Empirical Test of a Model of Resistance to Persuasion.

    ERIC Educational Resources Information Center

    And Others; Burgoon, Michael

    1978-01-01

    Tests a model of resistance to persuasion based upon variables not considered by earlier congruity and inoculation models. Supports the prediction that the kind of critical response set induced and the target of the criticism are mediators of resistance to persuasion. (JMF)

  12. A Preliminary Field Test of an Employee Work Passion Model

    ERIC Educational Resources Information Center

    Zigarmi, Drea; Nimon, Kim; Houson, Dobie; Witt, David; Diehl, Jim

    2011-01-01

    Four dimensions of a process model for the formulation of employee work passion, derived from Zigarmi, Nimon, Houson, Witt, and Diehl (2009), were tested in a field setting. A total of 447 employees completed questionnaires that assessed the internal elements of the model in a corporate work environment. Data from the measurements of work affect,…

  13. Using fMRI to Test Models of Complex Cognition

    ERIC Educational Resources Information Center

    Anderson, John R.; Carter, Cameron S.; Fincham, Jon M.; Qin, Yulin; Ravizza, Susan M.; Rosenberg-Lee, Miriam

    2008-01-01

    This article investigates the potential of fMRI to test assumptions about different components in models of complex cognitive tasks. If the components of a model can be associated with specific brain regions, one can make predictions for the temporal course of the BOLD response in these regions. An event-locked procedure is described for dealing…

  14. The Knowledge or Random Guessing Model for Matching Tests.

    ERIC Educational Resources Information Center

    van der Ven, A. H. G. S.; Gremmen, F. M.

    1992-01-01

    A statistical test of the knowledge or random guessing model is presented. A version of the model is introduced in which it is assumed that alternatives can be ordered according to a Guttman scale. Three examples illustrate its application to data from a total of 590 college students. (Author/SLD)

  15. The Nominal Response Model in Computerized Adaptive Testing.

    ERIC Educational Resources Information Center

    De Ayala, R. J.

    One important and promising application of item response theory (IRT) is computerized adaptive testing (CAT). The implementation of a nominal response model-based CAT (NRCAT) was studied. Item pool characteristics for the NRCAT as well as the comparative performance of the NRCAT and a CAT based on the three-parameter logistic (3PL) model were…

  16. San Francisco Bay test case for 3-D model verification

    USGS Publications Warehouse

    Smith, Peter E.

    1994-01-01

    This paper describes a field test case for 3-D hydrodynamic model verification using data from Carquinez Strait in San Francisco Bay, California. It will be disseminated by the ASCE Computational Hydraulics task committee on 3-D Free-Surface Hydrodynamic Model Verifications during late 1994.

  17. A Statistical Test for Comparing Nonnested Covariance Structure Models.

    ERIC Educational Resources Information Center

    Levy, Roy; Hancock, Gregory R.

    While statistical procedures are well known for comparing hierarchically related (nested) covariance structure models, statistical tests for comparing nonhierarchically related (nonnested) models have proven more elusive. While isolated attempts have been made, none exists within the commonly used maximum likelihood estimation framework, thereby…

  18. Software Testing and Verification in Climate Model Development

    NASA Technical Reports Server (NTRS)

    Clune, Thomas L.; Rood, RIchard B.

    2011-01-01

    Over the past 30 years most climate models have grown from relatively simple representations of a few atmospheric processes to a complex multi-disciplinary system. Computer infrastructure over that period has gone from punch card mainframes to modem parallel clusters. Model implementations have become complex, brittle, and increasingly difficult to extend and maintain. Existing verification processes for model implementations rely almost exclusively upon some combination of detailed analysis of output from full climate simulations and system-level regression tests. In additional to being quite costly in terms of developer time and computing resources, these testing methodologies are limited in terms of the types of defects that can be detected, isolated and diagnosed. Mitigating these weaknesses of coarse-grained testing with finer-grained "unit" tests has been perceived as cumbersome and counter-productive. In the commercial software sector, recent advances in tools and methodology have led to a renaissance for systematic fine-grained testing. We discuss the availability of analogous tools for scientific software and examine benefits that similar testing methodologies could bring to climate modeling software. We describe the unique challenges faced when testing complex numerical algorithms and suggest techniques to minimize and/or eliminate the difficulties.

  19. Scaling issues associated with thermal and structural modeling and testing

    SciTech Connect

    Thomas, R.K.; Moya, J.L.; Skocypec, R.D.

    1993-10-01

    Sandia National Laboratories (SNL) is actively engaged in research to characterize abnormal environments, and to improve our capability to accurately predict the response of engineered systems to thermal and structural events. Abnormal environments, such as impact and fire, are complex and highly nonlinear phenomena which are difficult to model by computer simulation. Validation of computer results with full scale, high fidelity test data is required. The number of possible abnormal environments and the range of initial conditions are very large. Because full-scale tests are very costly, only a minimal number have been conducted. Scale model tests are often performed to span the range of abnormal environments and initial conditions unobtainable by full-scale testing. This paper will discuss testing capabilities at SNL, issues associated with thermal and structural scaling, and issues associated with extrapolating scale model data to full-scale system response. Situated a few minutes from Albuquerque, New Mexico, are the unique test facilities of Sandia National Laboratories. The testing complex is comprised of over 40 facilities which occupy over 40 square miles. Many of the facilities have been designed and built by SNL to simulate complex problems encountered in engineering analysis and design. The facilities can provide response measurements, under closely controlled conditions, to both verify mathematical models of engineered systems and satisfy design specifications.

  20. Tests and models of nociception and pain in rodents.

    PubMed

    Barrot, M

    2012-06-01

    Nociception and pain is a large field of both neuroscience and medical research. Over time, various tests and models were developed in rodents to provide tools for fundamental and translational research on the topic. Tests using thermal, mechanical, and chemical stimuli, measures of hyperalgesia and allodynia, models of inflammatory or neuropathic pain, constitute a toolbox available to researchers. These tests and models allowed rapid progress on the anatomo-molecular basis of physiological and pathological pain, even though they have yet to translate into new analgesic drugs. More recently, a growing effort has been put forth trying to assess pain in rats or mice, rather than nociceptive reflexes, or at studying complex states affected by chronic pain. This aids to further improve the translational value of preclinical research in a field with balanced research efforts between fundamental research, preclinical work, and human studies. This review describes classical tests and models of nociception and pain in rodents. It also presents some recent and ongoing developments in nociceptive tests, recent trends for pain evaluation, and raises the question of the appropriateness between tests, models, and procedures.

  1. Modeling cross-hole slug tests in an unconfined aquifer

    NASA Astrophysics Data System (ADS)

    Malama, Bwalya; Kuhlman, Kristopher L.; Brauchler, Ralf; Bayer, Peter

    2016-09-01

    A modified version of a published slug test model for unconfined aquifers is applied to cross-hole slug test data collected in field tests conducted at the Widen site in Switzerland. The model accounts for water-table effects using the linearized kinematic condition. The model also accounts for inertial effects in source and observation wells. The primary objective of this work is to demonstrate applicability of this semi-analytical model to multi-well and multi-level pneumatic slug tests. The pneumatic perturbation was applied at discrete intervals in a source well and monitored at discrete vertical intervals in observation wells. The source and observation well pairs were separated by distances of up to 4 m. The analysis yielded vertical profiles of hydraulic conductivity, specific storage, and specific yield at observation well locations. The hydraulic parameter estimates are compared to results from prior pumping and single-well slug tests conducted at the site, as well as to estimates from particle size analyses of sediment collected from boreholes during well installation. The results are in general agreement with results from prior tests and are indicative of a sand and gravel aquifer. Sensitivity analysis show that model identification of specific yield is strongest at late-time. However, the usefulness of late-time data is limited due to the low signal-to-noise ratios.

  2. Corrective action unit modeling approach for the underground test area, Nevada Test Site, Nye County, Nevada

    SciTech Connect

    1998-03-01

    The modeling approach serves as a template for the development, application, and interpretation of the Corrective Action Unit (CAU) - scale saturated groundwater flow and transport model (herein called the CAU model) to be used for forecasting radionuclide migration in all Nevada Test Site (NTS) CAUs, consistent with the Federal Facility Agreement and Consent Order (FFACO) and Underground Test Area (UGTA) strategy. A summary of the project background, the FFACO and strategy, and the roles of participating agencies, is provided followed by a description of the contents of the document.

  3. Semi-span model testing in the National Transonic Facility

    NASA Technical Reports Server (NTRS)

    Chokani, Ndaona; Milholen, William E., II

    1993-01-01

    A semi-span testing technique has been proposed for the NASA Langley Research Center's National Transonic Facility (NTF). Semi-span testing has several advantages including (1) larger model size, giving increased Reynolds number capability; (2) improved model fidelity, allowing ease of flap and slat positioning which ultimately improves data quality; and (3) reduced construction costs compared with a full-span model. In addition, the increased model size inherently allows for increased model strength, reducing aeroelastic effects at the high dynamic pressure levels necessary to simulate flight Reynolds numbers. The Energy Efficient Transport (EET) full-span model has been modified to become the EET semi-span model. The full-span EET model was tested extensively at both NASA LRC and NASA Ames Research Center. The available full-span data will be useful in validating the semi-span test strategy in the NTF. In spite of the advantages discussed above, the use of a semi-span model does introduce additional challenges which must be addressed in the testing procedure. To minimize the influence of the sidewall boundary layer on the flow over the semi-span model, the model must be off-set from the sidewall. The objective is to remove the semi-span model from the sidewall boundary layer by use of a stand-off geometry. When this is done however, the symmetry along the centerline of the full-span model is lost when the semi-span model is mounted on the wind tunnel sidewall. In addition, the large semi-span model will impose a significant pressure loading on the sidewall boundary layer, which may cause separation. Even under flow conditions where the sidewall boundary layer remains attached, the sidewall boundary layer may adversely effect the flow over the semi-span model. Also, the increased model size and sidewall mounting requires a modified wall correction strategy. With these issues in mind, the semi-span model has been well instrumented with surface pressure taps to

  4. Reaction times to weak test lights. [psychophysics biological model

    NASA Technical Reports Server (NTRS)

    Wandell, B. A.; Ahumada, P.; Welsh, D.

    1984-01-01

    Maloney and Wandell (1984) describe a model of the response of a single visual channel to weak test lights. The initial channel response is a linearly filtered version of the stimulus. The filter output is randomly sampled over time. Each time a sample occurs there is some probability increasing with the magnitude of the sampled response - that a discrete detection event is generated. Maloney and Wandell derive the statistics of the detection events. In this paper a test is conducted of the hypothesis that the reaction time responses to the presence of a weak test light are initiated at the first detection event. This makes it possible to extend the application of the model to lights that are slightly above threshold, but still within the linear operating range of the visual system. A parameter-free prediction of the model proposed by Maloney and Wandell for lights detected by this statistic is tested. The data are in agreement with the prediction.

  5. Atmospheric Probe Model: Construction and Wind Tunnel Tests

    NASA Technical Reports Server (NTRS)

    Vogel, Jerald M.

    1998-01-01

    The material contained in this document represents a summary of the results of a low speed wind tunnel test program to determine the performance of an atmospheric probe at low speed. The probe configuration tested consists of a 2/3 scale model constructed from a combination of hard maple wood and aluminum stock. The model design includes approximately 130 surface static pressure taps. Additional hardware incorporated in the baseline model provides a mechanism for simulating external and internal trailing edge split flaps for probe flow control. Test matrix parameters include probe side slip angle, external/internal split flap deflection angle, and trip strip applications. Test output database includes surface pressure distributions on both inner and outer annular wings and probe center line velocity distributions from forward probe to aft probe locations.

  6. Rapid Model Fabrication and Testing for Aerospace Vehicles

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M.

    2000-01-01

    Advanced methods for rapid fabrication and instrumentation of hypersonic wind tunnel models are being developed and evaluated at NASA Langley Research Center. Rapid aeroheating model fabrication and measurement techniques using investment casting of ceramic test models and thermographic phosphors are reviewed. More accurate model casting techniques for fabrication of benchmark metal and ceramic test models are being developed using a combination of rapid prototype patterns and investment casting. White light optical scanning is used for coordinate measurements to evaluate the fabrication process and verify model accuracy to +/- 0.002 inches. Higher-temperature (<210C) luminescent coatings are also being developed for simultaneous pressure and temperature mapping, providing global pressure as well as global aeroheating measurements. Together these techniques will provide a more rapid and complete experimental aerodynamic and aerothermodynamic database for future aerospace vehicles.

  7. Calculation of flight vibration levels of the AH-1G helicopter and correlation with existing flight vibration measurements

    NASA Technical Reports Server (NTRS)

    Sopher, R.; Twomey, W. J.

    1990-01-01

    NASA-Langley is sponsoring a rotorcraft structural dynamics program with the objective to establish in the U.S. a superior capability to utilize finite element analysis models for calculations to support industrial design of helicopter airframe structures. In the initial phase of the program, teams from the major U.S. manufacturers of helicopter airframes will apply extant finite element analysis methods to calculate loads and vibrations of helicopter airframes, and perform correlations between analysis and measurements. The aforementioned rotorcraft structural dynamics program was given the acronym DAMVIBS (Design Analysis Method for Vibrations). Sikorsky's RDYNE Rotorcraft Dynamics Analysis used for the correlation study, the specifics of the application of RDYNE to the AH-1G, and comparisons of the predictions of the method with flight data for loads and vibrations on the AH-1G are described. RDYNE was able to predict trends of variations of loads and vibrations with airspeed, but in some instances magnitudes differed from measured results by factors of two or three to one. Sensitivities were studied of predictions to rotor inflow modeling, effects of torsional modes, number of blade bending modes, fuselage structural damping, and hub modal content.

  8. Classifiers as a model-free group comparison test.

    PubMed

    Kim, Bommae; Oertzen, Timo von

    2017-04-03

    The conventional statistical methods to detect group differences assume correct model specification, including the origin of difference. Researchers should be able to identify a source of group differences and choose a corresponding method. In this paper, we propose a new approach of group comparison without model specification using classification algorithms in machine learning. In this approach, the classification accuracy is evaluated against a binomial distribution using Independent Validation. As an application example, we examined false-positive errors and statistical power of support vector machines to detect group differences in comparison to conventional statistical tests such as t test, Levene's test, K-S test, Fisher's z-transformation, and MANOVA. The SVMs detected group differences regardless of their origins (mean, variance, distribution shape, and covariance), and showed comparably consistent power across conditions. When a group difference originated from a single source, the statistical power of SVMs was lower than the most appropriate conventional test of the study condition; however, the power of SVMs increased when differences originated from multiple sources. Moreover, SVMs showed substantially improved performance with more variables than with fewer variables. Most importantly, SVMs were applicable to any types of data without sophisticated model specification. This study demonstrates a new application of classification algorithms as an alternative or complement to the conventional group comparison test. With the proposed approach, researchers can test two-sample data even when they are not certain which statistical test to use or when data violates the statistical assumptions of conventional methods.

  9. Animal models of toxicology testing: the role of pigs.

    PubMed

    Helke, Kristi L; Swindle, Marvin Michael

    2013-02-01

    In regulatory toxicological testing, both a rodent and non-rodent species are required. Historically, dogs and non-human primates (NHP) have been the species of choice of the non-rodent portion of testing. The pig is an appropriate option for these tests based on metabolic pathways utilized in xenobiotic biotransformation. This review focuses on the Phase I and Phase II biotransformation pathways in humans and pigs and highlights the similarities and differences of these models. This is a growing field and references are sparse. Numerous breeds of pigs are discussed along with specific breed differences in these enzymes that are known. While much available data are presented, it is grossly incomplete and sometimes contradictory based on methods used. There is no ideal species to use in toxicology. The use of dogs and NHP in xenobiotic testing continues to be the norm. Pigs present a viable and perhaps more reliable model of non-rodent testing.

  10. Delta undulator model: Magnetic field and beam test results

    NASA Astrophysics Data System (ADS)

    Temnykh, A.; Babzien, M.; Davis, D.; Fedurin, M.; Kusche, K.; Park, J.; Yakimenko, V.

    2011-09-01

    A novel type of in-vacuum Elliptical Polarization Undulator (EPU) magnet optimized for linac beam (Delta undulator) was developed at the Laboratory for Elementary-Particle Physics (LEPP) at Cornell University as part of insertion device development for the future Cornell 5 GeV Energy Recovery Source of coherent hard X-rays [1,7]. To evaluate mechanical, vacuum and magnetic properties of the magnet, a short 30 cm model with a 5 mm diameter round gap and a 2.4 cm period was built and tested in LEPP. The beam test of the Delta undulator model was conducted at Accelerator Test Facility (ATF) in BNL with ˜60 MeV linac beam. The beam testing results confirmed basic properties of the undulator magnet obtained through the magnetic field measurement. In the paper we describe the magnet design, techniques and setups used for the magnetic field measurement and the beam testing results.

  11. Evaluation of thermographic phosphor technology for aerodynamic model testing

    SciTech Connect

    Cates, M.R.; Tobin, K.W.; Smith, D.B.

    1990-08-01

    The goal for this project was to perform technology evaluations applicable to the development of higher-precision, higher-temperature aerodynamic model testing at Arnold Engineering Development Center (AEDC) in Tullahmoa, Tennessee. With the advent of new programs for design of aerospace craft that fly at higher speeds and altitudes, requirements for detailed understanding of high-temperature materials become very important. Model testing is a natural and critical part of the development of these new initiatives. The well-established thermographic phosphor techniques of the Applied Technology Division at Oak Ridge National Laboratory are highly desirable for diagnostic evaluation of materials and aerodynamic shapes as studied in model tests. Combining this state-of-the-art thermographic technique with modern, higher-temperature models will greatly improve the practicability of tests for the advanced aerospace vehicles and will provide higher precision diagnostic information for quantitative evaluation of these tests. The wavelength ratio method for measuring surface temperatures of aerodynamic models was demonstrated in measurements made for this project. In particular, it was shown that the appropriate phosphors could be selected for the temperature range up to {approximately}700 {degree}F or higher and emission line ratios of sufficient sensitivity to measure temperature with 1% precision or better. Further, it was demonstrated that two-dimensional image- processing methods, using standard hardware, can be successfully applied to surface thermography of aerodynamic models for AEDC applications.

  12. Model of ASTM Flammability Test in Microgravity: Iron Rods

    NASA Technical Reports Server (NTRS)

    Steinberg, Theodore A; Stoltzfus, Joel M.; Fries, Joseph (Technical Monitor)

    2000-01-01

    There is extensive qualitative results from burning metallic materials in a NASA/ASTM flammability test system in normal gravity. However, this data was shown to be inconclusive for applications involving oxygen-enriched atmospheres under microgravity conditions by conducting tests using the 2.2-second Lewis Research Center (LeRC) Drop Tower. Data from neither type of test has been reduced to fundamental kinetic and dynamic systems parameters. This paper reports the initial model analysis for burning iron rods under microgravity conditions using data obtained at the LERC tower and modeling the burning system after ignition. Under the conditions of the test the burning mass regresses up the rod to be detached upon deceleration at the end of the drop. The model describes the burning system as a semi-batch, well-mixed reactor with product accumulation only. This model is consistent with the 2.0-second duration of the test. Transient temperature and pressure measurements are made on the chamber volume. The rod solid-liquid interface melting rate is obtained from film records. The model consists of a set of 17 non-linear, first-order differential equations which are solved using MATLAB. This analysis confirms that a first-order rate, in oxygen concentration, is consistent for the iron-oxygen kinetic reaction. An apparent activation energy of 246.8 kJ/mol is consistent for this model.

  13. Computer model to simulate testing at the National Transonic Facility

    NASA Technical Reports Server (NTRS)

    Mineck, Raymond E.; Owens, Lewis R., Jr.; Wahls, Richard A.; Hannon, Judith A.

    1995-01-01

    A computer model has been developed to simulate the processes involved in the operation of the National Transonic Facility (NTF), a large cryogenic wind tunnel at the Langley Research Center. The simulation was verified by comparing the simulated results with previously acquired data from three experimental wind tunnel test programs in the NTF. The comparisons suggest that the computer model simulates reasonably well the processes that determine the liquid nitrogen (LN2) consumption, electrical consumption, fan-on time, and the test time required to complete a test plan at the NTF. From these limited comparisons, it appears that the results from the simulation model are generally within about 10 percent of the actual NTF test results. The use of actual data acquisition times in the simulation produced better estimates of the LN2 usage, as expected. Additional comparisons are needed to refine the model constants. The model will typically produce optimistic results since the times and rates included in the model are typically the optimum values. Any deviation from the optimum values will lead to longer times or increased LN2 and electrical consumption for the proposed test plan. Computer code operating instructions and listings of sample input and output files have been included.

  14. Model of ASTM Flammability Test in Microgravity: Iron Rods

    NASA Technical Reports Server (NTRS)

    Steinberg, Theodore A; Stoltzfus, Joel M.; Fries, Joseph (Technical Monitor)

    2000-01-01

    There is extensive qualitative results from burning metallic materials in a NASA/ASTM flammability test system in normal gravity. However, this data was shown to be inconclusive for applications involving oxygen-enriched atmospheres under microgravity conditions by conducting tests using the 2.2-second Lewis Research Center (LeRC) Drop Tower. Data from neither type of test has been reduced to fundamental kinetic and dynamic systems parameters. This paper reports the initial model analysis for burning iron rods under microgravity conditions using data obtained at the LERC tower and modeling the burning system after ignition. Under the conditions of the test the burning mass regresses up the rod to be detached upon deceleration at the end of the drop. The model describes the burning system as a semi-batch, well-mixed reactor with product accumulation only. This model is consistent with the 2.0-second duration of the test. Transient temperature and pressure measurements are made on the chamber volume. The rod solid-liquid interface melting rate is obtained from film records. The model consists of a set of 17 non-linear, first-order differential equations which are solved using MATLAB. This analysis confirms that a first-order rate, in oxygen concentration, is consistent for the iron-oxygen kinetic reaction. An apparent activation energy of 246.8 kJ/mol is consistent for this model.

  15. Modeling cross-hole slug tests in an unconfined aquifer

    DOE PAGES

    Malama, Bwalya; Kuhlman, Kristopher L.; Brauchler, Ralf; ...

    2016-06-28

    Cross-hole slug test date are analyzed with an extended version of a recently published unconfined aquifer model accounting for waterable effects using the linearized kinematic condition. The use of cross-hole slug test data to characterize aquifer heterogeneity and source/observation well oscillation parameters is evaluated. The data were collected in a series of multi-well and multi-level pneumatic slug tests conducted at a site in Widen, Switzerland. Furthermore, the tests involved source and observation well pairs separated by distances of up to 4 m, and instrumented with pressure transducers to monitor aquifer response in discrete intervals.

  16. Preliminary results of steel containment vessel model test

    SciTech Connect

    Luk, V.K.; Hessheimer, M.F.; Matsumoto, T.; Komine, K.; Arai, S.; Costello, J.F.

    1998-04-01

    A high pressure test of a mixed-scaled model (1:10 in geometry and 1:4 in shell thickness) of a steel containment vessel (SCV), representing an improved boiling water reactor (BWR) Mark II containment, was conducted on December 11--12, 1996 at Sandia National Laboratories. This paper describes the preliminary results of the high pressure test. In addition, the preliminary post-test measurement data and the preliminary comparison of test data with pretest analysis predictions are also presented.

  17. Criterion-Referenced Testing: A Critical Analysis of Selected Models

    DTIC Science & Technology

    1978-08-01

    parameter loqis- tic model ( Rasch , 1960; Wrigh t , 1967) provides a practical example of how latent trait theory may be applied to CRT data analysis...App~lications. A more detailed example will show how the Rasch model was used to analyze the results of a criterion—re...dentify by block niwb.r) Criterion—referenced testing Decisionmaking Bayesian statistics Rasch model Classification error 20. A $TRAC? (C ,tlaoc

  18. On the Testing of Inflationary Cosmological Models with Missing Energy

    NASA Astrophysics Data System (ADS)

    Wang, Limin

    We try to constrain cosmological models by combining observational tests. By detailed study of the theoretical predictions, we show that a substantial range of cosmological models satisfy all the current available observations. Key cosmological parameters such as the matter density of the universe, the Hubble constant and the baryonic density of the universe are well constrained by the observations. We also study the prospect of further discriminating between competing models by utilizing future high precision observations.

  19. Metallothionein 1G promotes the differentiation of HT-29 human colorectal cancer cells

    PubMed Central

    Arriaga, Juan Martín; Bravo, Alicia Inés; Mordoh, José; Bianchini, Michele

    2017-01-01

    Metallothioneins (MTs) are a family of low- molecular-weight, cysteine-rich proteins involved in zinc and redox metabolism, that are epigenetically downregulated during colorectal cancer (CRC) progression, but may be re-induced with a variety of agents. Since loss of MT expression is associated with a worse prognosis, in the present study we investigated the effects of overexpression of the most significantly downregulated isoform in CRC, namely MT1G, on the HT-29 cell line. Overexpression of MT1G resulted in xenograft tumors with an aberrant morphology, characterized by an evident increase in mucin-containing cells that were identified as goblet cells under electron microscopy. Immunohistochemical detection of CDX2 and cytokeratin 20 was also increased, as were goblet-cell and enterocyte-specific genes by qRT-PCR. Microarray analysis of gene expression confirmed the alteration of several differentiation signaling pathways, including the Notch pathway. Using sodium butyrate and post-confluent growth as inducers of differentiation, we demonstrated that MT1G does indeed play a functional role in promoting goblet over enterocyte differentiation in vitro. Labile zinc is also induced upon differentiation of CRC cells, functionally contributing to enterocyte over goblet differentiation, as revealed using zinc-specific chelating agents. Overall, our results uncover a new tumor-suppressor activity of MT1G in promoting the differentiation of at least some CRC tumors, and implicate MTs and zinc signaling as new players in colorectal differentiation. This further contributes to the hypothesis that re-induction of MTs may have therapeutic value by diminishing the aggressiveness of CRC tumors. PMID:28393194

  20. Impaired reality testing in an animal model of schizophrenia.

    PubMed

    McDannald, Michael A; Whitt, Joshua P; Calhoon, Gwendolyn G; Piantadosi, Patrick T; Karlsson, Rose-Marie; O'Donnell, Patricio; Schoenbaum, Geoffrey

    2011-12-15

    Schizophrenia is a chronic and devastating brain disorder characterized by hallucinations and delusions, symptoms reflecting impaired reality testing. Although animal models have captured negative symptoms and cognitive deficits associated with schizophrenia, none have addressed these defining, positive symptoms. Here we tested the performance of adults given neonatal ventral hippocampal lesions (NVHL), a neurodevelopmental model of schizophrenia, in two taste aversion procedures. Normal and NVHL rats formed aversions to a palatable food when the food was directly paired with nausea, but only NVHL rats formed a food aversion when the cue predicting that food was paired with nausea. The failure of NVHL rats to discriminate fully real from imagined food parallels the failure of people with schizophrenia to differentiate internal thoughts and beliefs from reality. These results further validate the NVHL model of schizophrenia and provide a means to assess impaired reality testing in variety of animal models. 2011 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  1. Impaired reality testing in an animal model of schizophrenia

    PubMed Central

    McDannald, Michael A.; Whitt, Joshua P.; Calhoon, Gwen G.; Piantadosi, Patrick T.; Karlsson, Rose M.; O’Donnell, Patricio; Schoenbaum, Geoffrey

    2011-01-01

    Background Schizophrenia is a chronic and devastating brain disorder characterized by hallucinations and delusions, symptoms reflecting impaired reality testing. While animal models have captured negative symptoms and cognitive deficits associated with schizophrenia, none have addressed these defining, positive symptoms. Methods Here we tested the performance of adults given neonatal ventral hippocampal lesions (NVHL), a neurodevelopmental model of schizophrenia, in two taste aversion procedures. Results Normal and NVHL rats formed aversions to a palatable food when the food was directly paired with nausea, but only NVHL rats formed a food aversion when the cue predicting that food was paired with nausea. The failure of NVHL rats to fully discriminate real from imagined food parallels the failure of people with schizophrenia to differentiate internal thoughts/beliefs from reality. Conclusions These results further validate the NVHL model of schizophrenia and provide a means of assessing impaired reality testing in variety of animal models. PMID:21798517

  2. Oil Production from Yarrowia lipolytica Po1g Using Rice Bran Hydrolysate

    PubMed Central

    Tsigie, Yeshitila Asteraye; Wang, Chun-Yuan; Kasim, Novy S.; Diem, Quy-Do; Huynh, Lien-Huong; Ho, Quoc-Phong; Truong, Chi-Thanh; Ju, Yi-Hsu

    2012-01-01

    The purpose of this study was to produce microbial oil from Yarrowia lipolytica Po1g grown in defatted rice bran hydrolysate. After removing oil from rice bran by Soxhlet extraction, the bran is subjected to acid hydrolysis with various sulfuric acid concentrations (1–4% v/v), reaction times (1–8 h), and reaction temperatures (60–120°C). The optimal conditions for maximum total sugar production from the hydrolysate were found to be 3% sulfuric acid at 90°C for 6 h. Glucose was the predominant sugar (43.20 ± 0.28 g/L) followed by xylose (4.93 ± 0.03 g/L) and arabinose (2.09 ± 0.01 g/L). The hydrolysate was subsequently detoxified by neutralization to reduce the amount of inhibitors such as 5-hydroxymethylfurfural (HMF) and furfural to increase its potential as a medium for culturing Y. lipolytica Po1g. Dry cell mass and lipid content of Y. lipolytica Po1g grown in detoxified defatted rice bran hydrolysate (DRBH) under optimum conditions were 10.75 g/L and 48.02%, respectively. PMID:22496604

  3. Complete genome of a European hepatitis C virus subtype 1g isolate: phylogenetic and genetic analyses

    PubMed Central

    Bracho, Maria A; Saludes, Verónica; Martró, Elisa; Bargalló, Ana; González-Candelas, Fernando; Ausina, Vicent

    2008-01-01

    Background Hepatitis C virus isolates have been classified into six main genotypes and a variable number of subtypes within each genotype, mainly based on phylogenetic analysis. Analyses of the genetic relationship among genotypes and subtypes are more reliable when complete genome sequences (or at least the full coding region) are used; however, so far 31 of 80 confirmed or proposed subtypes have at least one complete genome available. Of these, 20 correspond to confirmed subtypes of epidemic interest. Results We present and analyse the first complete genome sequence of a HCV subtype 1g isolate. Phylogenetic and genetic distance analyses reveal that HCV-1g is the most divergent subtype among the HCV-1 confirmed subtypes. Potential genomic recombination events between genotypes or subtype 1 genomes were ruled out. We demonstrate phylogenetic congruence of previously deposited partial sequences of HCV-1g with respect to our sequence. Conclusion In light of this, we propose changing the current status of its subtype-specific designation from provisional to confirmed. PMID:18533988

  4. Neocartilage formation in 1 g, simulated, and microgravity environments: implications for tissue engineering.

    PubMed

    Stamenković, Vlada; Keller, Georg; Nesic, Dobrila; Cogoli, Augusto; Grogan, Shawn Patrick

    2010-05-01

    The aim of this study was to analyze and compare the deposition of cartilage-specific extracellular matrix components and cellular organization in scaffold-free neocartilage produced in microgravity and simulated microgravity. Porcine chondrocytes were seeded (100 x 10(6)/mL) into cylindrical culture chambers (n = 8) and cultured in the following environments: (i) microgravity during the Flight 7S (Cervantes mission) on the International Space Station (ISS), (ii) simulated microgravity in a random positioning machine (RPM), and (iii) normal gravity (1 g, control). After 16 days, each neocartilage tissue was processed for histology, immunohistochemistry, quantitative real-time reverse transcriptase-polymerase chain reaction, and histomorphometric analysis. Weaker extracellular matrix staining of ISS neocartilage tissue was noted compared with both Earth-cultivated tissues. Higher collagen II/I expression ratios were observed in ISS samples compared with control tissue. Conversely, higher aggrecan/versican gene expression profiles were seen in control 1 g samples compared with microgravity samples. Cell density produced in microgravity was significantly reduced compared with the normal gravity neocartilage tissues. Tissue cultivated on the RPM showed intermediate characteristics compared with ISS and 1 g conditions. These data indicate that the RPM system does not sustain microgravity. Although microgravity impacts the development of in vitro generated cartilage, simulated microgravity using the RPM may be a useful tool to produce cartilaginous tissue grafts with fewer cells.

  5. GSD-1G and MPI-DING Reference Glasses for In Situ and Bulk Isotopic Determination

    USGS Publications Warehouse

    Jochum, K.P.; Wilson, S.A.; Abouchami, W.; Amini, M.; Chmeleff, J.; Eisenhauer, A.; Hegner, E.; Iaccheri, L.M.; Kieffer, B.; Krause, J.; McDonough, W.F.; Mertz-Kraus, R.; Raczek, I.; Rudnick, R.L.; Scholz, Donna K.; Steinhoefel, G.; Stoll, B.; Stracke, A.; Tonarini, S.; Weis, D.; Weis, U.; Woodhead, J.D.

    2011-01-01

    This paper contains the results of an extensive isotopic study of United States Geological Survey GSD-1G and MPI-DING reference glasses. Thirteen different laboratories were involved using high-precision bulk (TIMS, MC-ICP-MS) and microanalytical (LA-MC-ICP-MS, LA-ICP-MS) techniques. Detailed studies were performed to demonstrate the large-scale and small-scale homogeneity of the reference glasses. Together with previously published isotopic data from ten other laboratories, preliminary reference and information values as well as their uncertainties at the 95% confidence level were determined for H, O, Li, B, Si, Ca, Sr, Nd, Hf, Pb, Th and U isotopes using the recommendations of the International Association of Geoanalysts for certification of reference materials. Our results indicate that GSD-1G and the MPI-DING glasses are suitable reference materials for microanalytical and bulk analytical purposes. Ce document contient les r??sultats d'une importante ??tude isotopique des verres de r??f??rence USGS GSD-1G et MPI-DING. Treize laboratoires diff??rents ont particip?? au travers de techniques analytiques de haute pr??cision travaillant soit sur ??chantillon total (TIMS, MC-ICP-MS) soit par microanalyse ??in situ?? (LA-MC-ICP-MS, LA-ICP-MS). ?? 2010 The Authors. Geostandards and Geoanalytical Research ?? 2010 International Association of Geoanalysts.

  6. Therapeutic rAAVrh10 Mediated SOD1 Silencing in Adult SOD1G93A Mice and Nonhuman Primates

    PubMed Central

    Borel, Florie; Gernoux, Gwladys; Cardozo, Brynn; Metterville, Jake P.; Toro Cabreja, Gabriela C.; Song, Lina; Su, Qin; Gao, Guang Ping; Elmallah, Mai K.; Brown, Robert H.; Mueller, Christian

    2016-01-01

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease; survival in ALS is typically 3–5 years. No treatment extends patient survival by more than three months. Approximately 20% of familial ALS and 1–3% of sporadic ALS patients carry a mutation in the gene encoding superoxide dismutase 1 (SOD1). In a transgenic ALS mouse model expressing the mutant SOD1G93A protein, silencing the SOD1 gene prolongs survival. One study reports a therapeutic effect of silencing the SOD1 gene in systemically treated adult ALS mice; this was achieved with a short hairpin RNA, a silencing molecule that has raised multiple safety concerns, and recombinant adeno-associated virus (rAAV) 9. We report here a silencing method based on an artificial microRNA termed miR-SOD1 systemically delivered using adeno-associated virus rAAVrh10, a serotype with a demonstrated safety profile in CNS clinical trials. Silencing of SOD1 in adult SOD1G93A transgenic mice with this construct profoundly delayed both disease onset and death in the SOD1G93A mice, and significantly preserved muscle strength and motor and respiratory functions. We also document that intrathecal delivery of the same rAAVrh10-miR-SOD1 in nonhuman primates significantly and safely silences SOD1 in lower motor neurons. This study supports the view that rAAVrh10-miR-SOD1 merits further development for the treatment of SOD1-linked ALS in humans. PMID:26710998

  7. Seeking homeostasis: temporal trends in respiration, oxidation, and calcium in SOD1 G93A Amyotrophic Lateral Sclerosis mice

    PubMed Central

    Irvin, Cameron W.; Kim, Renaid B.; Mitchell, Cassie S.

    2015-01-01

    Impairments in mitochondria, oxidative regulation, and calcium homeostasis have been well documented in numerous Amyotrophic Lateral Sclerosis (ALS) experimental models, especially in the superoxide dismutase 1 glycine 93 to alanine (SOD1 G93A) transgenic mouse. However, the timing of these deficiencies has been debatable. In a systematic review of 45 articles, we examine experimental measurements of cellular respiration, mitochondrial mechanisms, oxidative markers, and calcium regulation. We evaluate the quantitative magnitude and statistical temporal trend of these aggregated assessments in high transgene copy SOD1 G93A mice compared to wild type mice. Analysis of overall trends reveals cellular respiration, intracellular adenosine triphosphate, and corresponding mitochondrial elements (Cox, cytochrome c, complex I, enzyme activity) are depressed for the entire lifespan of the SOD1 G93A mouse. Oxidant markers (H2O2, 8OH2′dG, MDA) are initially similar to wild type but are double that of wild type by the time of symptom onset despite early post-natal elevation of protective heat shock proteins. All aspects of calcium regulation show early disturbances, although a notable and likely compensatory convergence to near wild type levels appears to occur between 40 and 80 days (pre-onset), followed by a post-onset elevation in intracellular calcium. The identified temporal trends and compensatory fluctuations provide evidence that the “cause” of ALS may lay within failed homeostatic regulation, itself, rather than any one particular perturbing event or cellular mechanism. We discuss the vulnerabilities of motoneurons to regulatory instability and possible hypotheses regarding failed regulation and its potential treatment in ALS. PMID:26190973

  8. Computational Modeling of NEXT 2000-Hour Wear Test Results

    NASA Technical Reports Server (NTRS)

    Malone, Shane P.

    2004-01-01

    Ion optics computational models are invaluable tools for the design of ion optics systems. In this study, a new computational model developed by an outside vendor for NASA Glenn Research Center (GRC) is presented. This model is a gun code which has been modified to model the plasma sheaths both upstream and downstream of the ion optics. The model handles multiple species (e.g. singly and doubly-charged ions) and includes a charge-exchange model for erosion estimates. The model uses commercially available solid design and meshing software, allowing high flexibility in ion optics geometric configurations. This computational model is compared to experimental results from the NASA Evolutionary Xenon Thruster (NEXT) 2000-hour wear test, including over-focusing along the edge apertures, pit-and-groove erosion due to charge exchange, and beamlet distortion at the edge of the hole pattern.

  9. Aeroservoelastic Testing of Free Flying Wind Tunnel Models Part 2: A Centerline Supported Fullspan Model Tested for Gust Load Alleviation

    NASA Technical Reports Server (NTRS)

    Scott, Robert C.; Vetter, Travis K.; Penning, Kevin B.; Coulson, David A.; Heeg, Jennifer

    2014-01-01

    This is part 2 of a two part document. Part 1 is titled: "Aeroservoelastic Testing of Free Flying Wind Tunnel Models Part 1: A Sidewall Supported Semispan Model Tested for Gust Load Alleviation and Flutter Suppression." A team comprised of the Air Force Research Laboratory (AFRL), Boeing, and the NASA Langley Research Center conducted three aeroservoelastic wind tunnel tests in the Transonic Dynamics Tunnel to demonstrate active control technologies relevant to large, flexible vehicles. In the first of these three tests, a full-span, aeroelastically scaled, wind tunnel model of a joined wing SensorCraft vehicle was mounted to a force balance to acquire a basic aerodynamic data set. In the second and third tests, the same wind tunnel model was mated to a new, two degree of freedom, beam mount. This mount allowed the full-span model to translate vertically and pitch. Trimmed flight at10 percent static margin and gust load alleviation were successfully demonstrated. The rigid body degrees of freedom required that the model be flown in the wind tunnel using an active control system. This risky mode of testing necessitated that a model arrestment system be integrated into the new mount. The safe and successful completion of these free-flying tests required the development and integration of custom hardware and software. This paper describes the many systems, software, and procedures that were developed as part of this effort. The balance and free flying wind tunnel tests will be summarized. The design of the trim and gust load alleviation control laws along with the associated results will also be discussed.

  10. Development of Test-Analysis Models (TAM) for correlation of dynamic test and analysis results

    NASA Technical Reports Server (NTRS)

    Angelucci, Filippo; Javeed, Mehzad; Mcgowan, Paul

    1992-01-01

    The primary objective of structural analysis of aerospace applications is to obtain a verified finite element model (FEM). The verified FEM can be used for loads analysis, evaluate structural modifications, or design control systems. Verification of the FEM is generally obtained as the result of correlating test and FEM models. A test analysis model (TAM) is very useful in the correlation process. A TAM is essentially a FEM reduced to the size of the test model, which attempts to preserve the dynamic characteristics of the original FEM in the analysis range of interest. Numerous methods for generating TAMs have been developed in the literature. The major emphasis of this paper is a description of the procedures necessary for creation of the TAM and the correlation of the reduced models with the FEM or the test results. Herein, three methods are discussed, namely Guyan, Improved Reduced System (IRS), and Hybrid. Also included are the procedures for performing these analyses using MSC/NASTRAN. Finally, application of the TAM process is demonstrated with an experimental test configuration of a ten bay cantilevered truss structure.

  11. Modal Test Experiences with a Jet Engine Fan Model

    NASA Astrophysics Data System (ADS)

    HOLLKAMP, J. J.; GORDON, R. W.

    2001-11-01

    High cycle fatigue in jet engine blades is caused by excessive vibration. Understanding the dynamic response of the bladed disk system is important in determining vibration levels. Modal testing is a useful tool in understanding the dynamic behavior of structures. However, modal tests are not conducted on bladed disks because of the difficulties involved. One problem is that the overall dynamic behavior is sensitive to small perturbations. Another problem is that multiple inputs and high-resolution techniques are required to separate modes that are nearly repeated. Two studies of engine blade response were recently completed in which bench modal tests were successfully performed on simplified fan models. The modal test procedures for the first study were successful in extracting the modal parameters. But the tests in the second study were more demanding. Ultimately, an approach was devised that accurately extracted the modal parameters. This paper describes the challenges and the evolution of the test procedures.

  12. SPSS and SAS programming for the testing of mediation models.

    PubMed

    Dudley, William N; Benuzillo, Jose G; Carrico, Mineh S

    2004-01-01

    Mediation modeling can explain the nature of the relation among three or more variables. In addition, it can be used to show how a variable mediates the relation between levels of intervention and outcome. The Sobel test, developed in 1990, provides a statistical method for determining the influence of a mediator on an intervention or outcome. Although interactive Web-based and stand-alone methods exist for computing the Sobel test, SPSS and SAS programs that automatically run the required regression analyses and computations increase the accessibility of mediation modeling to nursing researchers. To illustrate the utility of the Sobel test and to make this programming available to the Nursing Research audience in both SAS and SPSS. The history, logic, and technical aspects of mediation testing are introduced. The syntax files sobel.sps and sobel.sas, created to automate the computation of the regression analysis and test statistic, are available from the corresponding author. The reported programming allows the user to complete mediation testing with the user's own data in a single-step fashion. A technical manual included with the programming provides instruction on program use and interpretation of the output. Mediation modeling is a useful tool for describing the relation between three or more variables. Programming and manuals for using this model are made available.

  13. New Model Atmospheres: Testing the Solar Spectrum in the UV

    NASA Astrophysics Data System (ADS)

    Rodríguez-Merino, L. H.; Cardona, O.; Bertone, E.; Chávez, M.; Buzzoni, A.

    2009-03-01

    We present preliminary results on the calculation of synthetic spectra obtained with the stellar model atmospheres developed by Cardona, Crivellari, and Simonneau. These new models have been used as input within the Synthe series of codes developed by Kurucz. As a first step we have tested if Synthe is able to handle these models which go down to log{τ_{Ross}}= -13. We have successfully calculated a synthetic solar spectrum in the wavelength region 2000-4500 Å at high resolution (R=522 000). Within this initial test we have found that layers at optical depths with log{τ_{Ross}} < -7 significantly affect the mid-UV properties of a synthetic spectrum computed from a solar model. We anticipate that these new extended models will be a valuable tool for the analysis of UV stellar light arising from the outermost layers of the atmospheres.

  14. In Search of Optimal Cognitive Diagnostic Model(s) for ESL Grammar Test Data

    ERIC Educational Resources Information Center

    Yi, Yeon-Sook

    2017-01-01

    This study compares five cognitive diagnostic models in search of optimal one(s) for English as a Second Language grammar test data. Using a unified modeling framework that can represent specific models with proper constraints, the article first fit the full model (the log-linear cognitive diagnostic model, LCDM) and investigated which model…

  15. The Rasch Model as a Criterion: Applying the Rasch Model to the Analysis of Test Heterogeneity.

    ERIC Educational Resources Information Center

    Lindstrom, Berner

    The aim of this paper is to explore the Rasch model as a criterion of test homogeneity. Two empirical studies are presented to demonstrate this usage. From these studies it is argued that statistical tests of item characteristic curve (ICC) slopes are not sufficient in testing for heterogeneity. Tests of equality of ICC's over groups of subject…

  16. Modeling Local Item Dependence Due to Common Test Format with a Multidimensional Rasch Model

    ERIC Educational Resources Information Center

    Baghaei, Purya; Aryadoust, Vahid

    2015-01-01

    Research shows that test method can exert a significant impact on test takers' performance and thereby contaminate test scores. We argue that common test method can exert the same effect as common stimuli and violate the conditional independence assumption of item response theory models because, in general, subsets of items which have a shared…

  17. Modeling Local Item Dependence Due to Common Test Format with a Multidimensional Rasch Model

    ERIC Educational Resources Information Center

    Baghaei, Purya; Aryadoust, Vahid

    2015-01-01

    Research shows that test method can exert a significant impact on test takers' performance and thereby contaminate test scores. We argue that common test method can exert the same effect as common stimuli and violate the conditional independence assumption of item response theory models because, in general, subsets of items which have a shared…

  18. 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.

  19. Influence of matrix metalloproteinase-1 gene -1607 (1G/2G) (rs1799750) promoter polymorphism on circulating levels of MMP-1 in chronic pancreatitis.

    PubMed

    Sri Manjari, K; Nallari, Pratibha; Balakrishna, N; Vidyasagar, A; Prabhakar, B; Jyothy, A; Venkateshwari, A

    2013-08-01

    This study investigated the role of -1607 (1G/2G) (rs1799750) polymorphism of the MMP-1 gene in chronic pancreatitis. We genotyped 100 patients with chronic pancreatitis and 100 control subjects using tetra-primer ARMS-PCR followed by agarose gel electrophoresis. Serum levels of MMP-1 were determined by Elisa. Statistical analysis was applied to test the significance of the results. The genotypic and allelic distribution varied significantly between the disease group and the control subjects [OD = 1.981 (1.236-3.181), p = 0.004]. MMP-1 levels were higher in subjects homozygous for the 2G allele than in subjects with the 1G allele. The present study revealed a significant association of the MMP-1 -1607 1G/2G (rs1799750) gene promoter polymorphism with chronic pancreatitis, and it can be considered a biological marker in the etiology of chronic pancreatitis.

  20. Hygrothermal modeling and testing of polymers and polymer matrix composites

    NASA Astrophysics Data System (ADS)

    Xu, Weiqun

    2000-10-01

    The dissertation, consisting of four papers, presents the results of the research investigation on environmental effects on polymers and polymer matrix composites. Hygrothermal models were developed that would allow characterization of non-Fickian diffusion coefficients from moisture weight gain data. Hygrothermal testing was also conducted to provide the necessary data for characterizing of model coefficients and model verification. In part 1, a methodology is proposed that would allow characterization of non-Fickian diffusion coefficients from moisture weight gain data for a polymer adhesive below its Tg. Subsequently, these diffusion coefficients are used for predicting moisture concentration profiles through the thickness of a polymer. In part 2, a modeling methodology based on irreversible thermodynamics applied within the framework of composite macro-mechanics is presented, that would allow characterization of non-Fickian diffusion coefficients from moisture weight gain data for laminated composites with distributed uniaxial damage. Comparisons with test data for a 5-harness satin textile composite with uniaxial micro-cracks are provided for model verifications. In part 3, the same modeling methodology based on irreversible thermodynamics is extended to the case of a bi-axially damaged laminate. The model allows characterization of nonFickian diffusion coefficients as well as moisture saturation level from moisture weight gain data for laminates with pre-existing damage. Comparisons with test data for a bi-axially damaged Graphite/Epoxy woven composite are provided for model verifications. Finally, in part 4, hygrothermal tests conducted on AS4/PR500 5HS textile composite laminates are summarized. The objectives of the hygrothermal tests are to determine the diffusivity and maximum moisture content of the laminate.

  1. Asteroid modeling for testing spacecraft approach and landing.

    PubMed

    Martin, Iain; Parkes, Steve; Dunstan, Martin; Rowell, Nick

    2014-01-01

    Spacecraft exploration of asteroids presents autonomous-navigation challenges that can be aided by virtual models to test and develop guidance and hazard-avoidance systems. Researchers have extended and applied graphics techniques to create high-resolution asteroid models to simulate cameras and other spacecraft sensors approaching and descending toward asteroids. A scalable model structure with evenly spaced vertices simplifies terrain modeling, avoids distortion at the poles, and enables triangle-strip definition for efficient rendering. To create the base asteroid models, this approach uses two-phase Poisson faulting and Perlin noise. It creates realistic asteroid surfaces by adding both crater models adapted from lunar terrain simulation and multiresolution boulders. The researchers evaluated the virtual asteroids by comparing them with real asteroid images, examining the slope distributions, and applying a surface-relative feature-tracking algorithm to the models.

  2. Automated particulate sampler field test model operations guide

    SciTech Connect

    Bowyer, S.M.; Miley, H.S.

    1996-10-01

    The Automated Particulate Sampler Field Test Model Operations Guide is a collection of documents which provides a complete picture of the Automated Particulate Sampler (APS) and the Field Test in which it was evaluated. The Pacific Northwest National Laboratory (PNNL) Automated Particulate Sampler was developed for the purpose of radionuclide particulate monitoring for use under the Comprehensive Test Ban Treaty (CTBT). Its design was directed by anticipated requirements of small size, low power consumption, low noise level, fully automatic operation, and most predominantly the sensitivity requirements of the Conference on Disarmament Working Paper 224 (CDWP224). This guide is intended to serve as both a reference document for the APS and to provide detailed instructions on how to operate the sampler. This document provides a complete description of the APS Field Test Model and all the activity related to its evaluation and progression.

  3. Testing Modeling Assumptions in the West Africa Ebola Outbreak

    NASA Astrophysics Data System (ADS)

    Burghardt, Keith; Verzijl, Christopher; Huang, Junming; Ingram, Matthew; Song, Binyang; Hasne, Marie-Pierre

    2016-10-01

    The Ebola virus in West Africa has infected almost 30,000 and killed over 11,000 people. Recent models of Ebola Virus Disease (EVD) have often made assumptions about how the disease spreads, such as uniform transmissibility and homogeneous mixing within a population. In this paper, we test whether these assumptions are necessarily correct, and offer simple solutions that may improve disease model accuracy. First, we use data and models of West African migration to show that EVD does not homogeneously mix, but spreads in a predictable manner. Next, we estimate the initial growth rate of EVD within country administrative divisions and find that it significantly decreases with population density. Finally, we test whether EVD strains have uniform transmissibility through a novel statistical test, and find that certain strains appear more often than expected by chance.

  4. Active earth pressure model tests versus finite element analysis

    NASA Astrophysics Data System (ADS)

    Pietrzak, Magdalena

    2017-06-01

    The purpose of the paper is to compare failure mechanisms observed in small scale model tests on granular sample in active state, and simulated by finite element method (FEM) using Plaxis 2D software. Small scale model tests were performed on rectangular granular sample retained by a rigid wall. Deformation of the sample resulted from simple wall translation in the direction `from the soil" (active earth pressure state. Simple Coulomb-Mohr model for soil can be helpful in interpreting experimental findings in case of granular materials. It was found that the general alignment of strain localization pattern (failure mechanism) may belong to macro scale features and be dominated by a test boundary conditions rather than the nature of the granular sample.

  5. A modal test design strategy for model correlation

    SciTech Connect

    Carne, T.G.; Dohrmann, C.R.

    1994-12-01

    When a modal test is to be performed for purposes of correlation with a finite element model, one needs to design the test so that the resulting measurements will provide the data needed for the correlation. There are numerous issues to consider in the design of a modal test; two important ones are the number and location of response sensors, and the number, location, and orientation of input excitation. From a model correlation perspective, one would like to select the response locations to allow a definitive, one-to-one correspondence between the measured modes and the predicted modes. Further, the excitation must be designed to excite all the modes of interest at a sufficiently high level so that the modal estimation algorithms can accurately extract the modal parameters. In this paper these two issues are examined in the context of model correlation with methodologies presented for obtaining an experiment design.

  6. Testing Modeling Assumptions in the West Africa Ebola Outbreak

    PubMed Central

    Burghardt, Keith; Verzijl, Christopher; Huang, Junming; Ingram, Matthew; Song, Binyang; Hasne, Marie-Pierre

    2016-01-01

    The Ebola virus in West Africa has infected almost 30,000 and killed over 11,000 people. Recent models of Ebola Virus Disease (EVD) have often made assumptions about how the disease spreads, such as uniform transmissibility and homogeneous mixing within a population. In this paper, we test whether these assumptions are necessarily correct, and offer simple solutions that may improve disease model accuracy. First, we use data and models of West African migration to show that EVD does not homogeneously mix, but spreads in a predictable manner. Next, we estimate the initial growth rate of EVD within country administrative divisions and find that it significantly decreases with population density. Finally, we test whether EVD strains have uniform transmissibility through a novel statistical test, and find that certain strains appear more often than expected by chance. PMID:27721505

  7. Genetic ablation of IP3 receptor 2 increases cytokines and decreases survival of SOD1G93A mice

    PubMed Central

    Staats, Kim A.; Humblet-Baron, Stephanie; Bento-Abreu, Andre; Scheveneels, Wendy; Nikolaou, Alexandros; Deckers, Kato; Lemmens, Robin; Goris, An; Van Ginderachter, Jo A.; Van Damme, Philip; Hisatsune, Chihiro; Mikoshiba, Katsuhiko; Liston, Adrian; Robberecht, Wim; Van Den Bosch, Ludo

    2016-01-01

    Amyotrophic lateral sclerosis (ALS) is a devastating progressive neurodegenerative disease characterized by the selective death of motor neurons. Disease pathophysiology is complex and not yet fully understood. Higher gene expression of the inositol 1,4,5-trisphosphate receptor 2 gene (ITPR2), encoding the IP3 receptor 2 (IP3R2), was detected in sporadic ALS patients. Here, we demonstrate that IP3R2 gene expression was also increased in spinal cords of ALS mice. Moreover, an increase of IP3R2 expression was observed in other models of chronic and acute neurodegeneration. Upregulation of IP3R2 gene expression could be induced by lipopolysaccharide (LPS) in murine astrocytes, murine macrophages and human fibroblasts indicating that it may be a compensatory response to inflammation. Preventing this response by genetic deletion of ITPR2 from SOD1G93A mice had a dose-dependent effect on disease duration, resulting in a significantly shorter lifespan of these mice. In addition, the absence of IP3R2 led to increased innate immunity, which may contribute to the decreased survival of the SOD1G93A mice. Besides systemic inflammation, IP3R2 knockout mice also had increased IFNγ, IL-6 and IL1α expression. Altogether, our data indicate that IP3R2 protects against the negative effects of inflammation, suggesting that the increase in IP3R2 expression in ALS patients is a protective response. PMID:27378687

  8. A model based security testing method for protocol implementation.

    PubMed

    Fu, Yu Long; Xin, Xiao Long

    2014-01-01

    The security of protocol implementation is important and hard to be verified. Since the penetration testing is usually based on the experience of the security tester and the specific protocol specifications, a formal and automatic verification method is always required. In this paper, we propose an extended model of IOLTS to describe the legal roles and intruders of security protocol implementations, and then combine them together to generate the suitable test cases to verify the security of protocol implementation.

  9. A Model Based Security Testing Method for Protocol Implementation

    PubMed Central

    Fu, Yu Long; Xin, Xiao Long

    2014-01-01

    The security of protocol implementation is important and hard to be verified. Since the penetration testing is usually based on the experience of the security tester and the specific protocol specifications, a formal and automatic verification method is always required. In this paper, we propose an extended model of IOLTS to describe the legal roles and intruders of security protocol implementations, and then combine them together to generate the suitable test cases to verify the security of protocol implementation. PMID:25105163

  10. Acoustic results of the Boeing model 360 whirl tower test

    NASA Technical Reports Server (NTRS)

    Watts, Michael E.; Jordan, David

    1990-01-01

    An evaluation is presented for whirl tower test results of the Model 360 helicopter's advanced, high-performance four-bladed composite rotor system intended to facilitate over-200-knot flight. During these performance measurements, acoustic data were acquired by seven microphones. A comparison of whirl-tower tests with theory indicate that theoretical prediction accuracies vary with both microphone position and the inclusion of ground reflection. Prediction errors varied from 0 to 40 percent of the measured signal-to-peak amplitude.

  11. A Method to Test Model Calibration Techniques: Preprint

    SciTech Connect

    Judkoff, Ron; Polly, Ben; Neymark, Joel

    2016-09-01

    This paper describes a method for testing model calibration techniques. Calibration is commonly used in conjunction with energy retrofit audit models. An audit is conducted to gather information about the building needed to assemble an input file for a building energy modeling tool. A calibration technique is used to reconcile model predictions with utility data, and then the 'calibrated model' is used to predict energy savings from a variety of retrofit measures and combinations thereof. Current standards and guidelines such as BPI-2400 and ASHRAE-14 set criteria for 'goodness of fit' and assume that if the criteria are met, then the calibration technique is acceptable. While it is logical to use the actual performance data of the building to tune the model, it is not certain that a good fit will result in a model that better predicts post-retrofit energy savings. Therefore, the basic idea here is that the simulation program (intended for use with the calibration technique) is used to generate surrogate utility bill data and retrofit energy savings data against which the calibration technique can be tested. This provides three figures of merit for testing a calibration technique, 1) accuracy of the post-retrofit energy savings prediction, 2) closure on the 'true' input parameter values, and 3) goodness of fit to the utility bill data. The paper will also discuss the pros and cons of using this synthetic surrogate data approach versus trying to use real data sets of actual buildings.

  12. Distinct Element Modeling of the Large Block Test

    NASA Astrophysics Data System (ADS)

    Carlson, S. R.; Blair, S. C.; Wagoner, J. L.

    2001-12-01

    The Yucca Mountain Site Characterization Project is investigating Yucca Mountain, Nevada as a potential nuclear waste repository site. As part of this effort, the Large Block, a 3m x 3m x 4.5m rectangular prism of Topopah Spring tuff, was excavated at Fran Ridge near Yucca Mountain. The Large Block was heated to a peak temperature of 145\\deg C along a horizontal plane 2.75m below the top of the block over a period of about one-year. Displacements were measured in three orthogonal directions with an array of six Multiple Point Borehole Extensometers (MPBX) and were numerically simulated in three dimensions with 3DEC, a distinct element code. The distinct element method was chosen to incorporate discrete fractures in the simulations. The model domain was extended 23m below the ground surface and, in the subsurface, 23m outward from each vertical face so that fixed displacement boundary conditions could be applied well away from the heated portion of the block. A single continuum model and three distinct element models, incorporating six to twenty eight mapped fractures, were tested. Two thermal expansion coefficients were tested for the six-fracture model: a higher value taken from laboratory measurements and a lower value from an earlier field test. The MPBX data show that the largest displacements occurred in the upper portion of the block despite the higher temperatures near the center. The continuum model was found to under-predict the MPBX displacements except in the east west direction near the base of the block. The high thermal expansion model over-predicted the MPBX displacements except in the north south direction near the top of the block. The highly fractured model under-predicted most of the MPBX displacements and poorly simulated the cool-down portion of the test. Although no model provided the single best fit to all of the MPBX data, the six and seven fracture models consistently provided good fits and in most cases showed much improvement over the

  13. Model test vs virtual simulation of a VLCC FPSO hookup

    NASA Astrophysics Data System (ADS)

    Hao, Jun; Sun, Yu-Zhu; Wu, Zi-Quan; Wang, Alan

    2009-06-01

    This paper describes the model test and the virtual simulation respectively for the VLCC class FPSO hookup, as well as addresses their different applications to the mating operation between the FPSO and the soft yoke mooring system (SYMS) in extremely shallow water. The scope of the model test and the virtual simulation covers various installation stages including a series of positioning trials, positioning keeping and temporary mooring to the pre-installed SYMS mooring tower, pendulum mating, and yoke ballasting to storm-safe. The model test is to accurately verify bollard pull capacity to keep the FPSO in position and assess motion responses and mooring loads for the FPSO and installation vessels during various installation stages. The virtual simulation is to provide a virtual-reality environment, thus realistically replicating the hookup operation at the Simulation Test Center (STC) facility and identifying any deficiencies in key installation personnel, execution plan, or operation procedures. The methodologies of the model test and the virtual simulation addressed here can be easily extended to the deepwater applications such as positioning and installation operations of various floating systems.

  14. Results of a sub-scale model rotor icing test

    NASA Technical Reports Server (NTRS)

    Flemming, Robert J.; Bond, Thomas H.; Britton, Randall K.

    1991-01-01

    A heavily instrumented sub-scale model of a helicopter main rotor was tested in the NASA Lewis Research Center Icing Research Tunnel (IRT) in September and November 1989. The four-bladed main rotor had a diameter of 1.83 m (6.00 ft) and the 0.124 m (4.9 in) chord rotor blades were specially fabricated for this experiment. The instrumented rotor was mounted on a Sikorsky Aircraft Powered Force Model, which enclosed a rotor balance and other measurement systems. The model rotor was exposed to a range of icing conditions that included variations in temperature, liquid water content, and median droplet diameter, and was operated over ranges of advance ratio, shaft angle, tip Mach number (rotor speed) and weight coefficient to determine the effect of these parameters on ice accretion. In addition to strain gage and balance data, the test was documented with still, video, and high speed photography, ice profile tracings, and ice molds. The sensitivity of the model rotor to the test parameters, is given, and the result to theoretical predictions are compared. Test data quality was excellent, and ice accretion prediction methods and rotor performance prediction methods (using published icing lift and drag relationships) reproduced the performance trends observed in the test. Adjustments to the correlation coefficients to improve the level of correlation are suggested.

  15. Ground Contact Modeling for the Morpheus Test Vehicle Simulation

    NASA Technical Reports Server (NTRS)

    Cordova, Luis

    2013-01-01

    The Morpheus vertical test vehicle is an autonomous robotic lander being developed at Johnson Space Center (JSC) to test hazard detection technology. Because the initial ground contact simulation model was not very realistic, it was decided to improve the model without making it too computationally expensive. The first development cycle added capability to define vehicle attachment points (AP) and to keep track of their states in the lander reference frame (LFRAME). These states are used with a spring damper model to compute an AP contact force. The lateral force is then overwritten, if necessary, by the Coulomb static or kinetic friction force. The second development cycle added capability to use the PolySurface class as the contact surface. The class can load CAD data in STL (Stereo Lithography) format, and use the data to compute line of sight (LOS) intercepts. A polygon frame (PFRAME) is computed from the facet intercept normal and used to convert the AP state to PFRAME. Three flat plane tests validate the transitions from kinetic to static, static to kinetic, and vertical impact. The hazardous terrain test will be used to test for visual reasonableness. The improved model is numerically inexpensive, robust, and produces results that are reasonable.

  16. Bayes Factor Covariance Testing in Item Response Models.

    PubMed

    Fox, Jean-Paul; Mulder, Joris; Sinharay, Sandip

    2017-08-29

    Two marginal one-parameter item response theory models are introduced, by integrating out the latent variable or random item parameter. It is shown that both marginal response models are multivariate (probit) models with a compound symmetry covariance structure. Several common hypotheses concerning the underlying covariance structure are evaluated using (fractional) Bayes factor tests. The support for a unidimensional factor (i.e., assumption of local independence) and differential item functioning are evaluated by testing the covariance components. The posterior distribution of common covariance components is obtained in closed form by transforming latent responses with an orthogonal (Helmert) matrix. This posterior distribution is defined as a shifted-inverse-gamma, thereby introducing a default prior and a balanced prior distribution. Based on that, an MCMC algorithm is described to estimate all model parameters and to compute (fractional) Bayes factor tests. Simulation studies are used to show that the (fractional) Bayes factor tests have good properties for testing the underlying covariance structure of binary response data. The method is illustrated with two real data studies.

  17. Ground Contact Modeling for the Morpheus Test Vehicle Simulation

    NASA Technical Reports Server (NTRS)

    Cordova, Luis

    2014-01-01

    The Morpheus vertical test vehicle is an autonomous robotic lander being developed at Johnson Space Center (JSC) to test hazard detection technology. Because the initial ground contact simulation model was not very realistic, it was decided to improve the model without making it too computationally expensive. The first development cycle added capability to define vehicle attachment points (AP) and to keep track of their states in the lander reference frame (LFRAME). These states are used with a spring damper model to compute an AP contact force. The lateral force is then overwritten, if necessary, by the Coulomb static or kinetic friction force. The second development cycle added capability to use the PolySurface class as the contact surface. The class can load CAD data in STL (Stereo Lithography) format, and use the data to compute line of sight (LOS) intercepts. A polygon frame (PFRAME) is computed from the facet intercept normal and used to convert the AP state to PFRAME. Three flat plane tests validate the transitions from kinetic to static, static to kinetic, and vertical impact. The hazardous terrain test will be used to test for visual reasonableness. The improved model is numerically inexpensive, robust, and produces results that are reasonable.

  18. Cyclic Oxidation Testing and Modelling: A NASA Lewis Perspective

    NASA Technical Reports Server (NTRS)

    Smialek, J. L.; Nesbitt, J. A.; Barrett, C. A.; Lowell, C. E.

    2000-01-01

    The Materials Division of the NASA Lewis Research Center has been heavily involved in the cyclic oxidation of high temperature materials for 30 years. Cyclic furnace and burner rig apparati have been developed, refined, and replicated to provide a large scale facility capable of evaluating many materials by a standard technique. Material behavior is characterized by weight change data obtained throughout the test, which has been modelled in a step-wise process of scale growth and spallation. This model and a coupled diffusion model have successfully described cyclic behavior for a number of systems and have provided insights regarding life prediction and variations in the spalling process. Performance ranking and mechanistic studies are discussed primarily for superalloys and coating alloys. Similar cyclic oxidation studies have been performed on steels, intermetallic compounds, thermal barrier coatings, ceramics, and ceramic composites. The most common oxidation test was performed in air at temperatures ranging from 800 deg. to 1600 C, for times up to 10000 h, and for cycle durations of 0.1 to 1000 h. Less controlled, but important, test parameters are the cooling temperature and humidity level. Heating and cooling rates are not likely to affect scale spallation. Broad experience has usually allowed for considerable focus and simplification of these test parameters, while still revealing the principal aspects of material behavior and performance. Extensive testing has been performed to statistically model the compositional effects of experimental alloys and to construct a comprehensive database of complex commercial alloys.

  19. Comparison of Tests on Air Propellers in Flight with Wind Tunnel Model Tests on Similar Forms

    NASA Technical Reports Server (NTRS)

    Durand, W F; Lesley, E P

    1926-01-01

    The purpose of this investigation was to determine the performance, characteristics, and coefficients of full-sized air propellers in flight and to compare these results with those derived from wind-tunnel tests on reduced scale models of similar geometrical form. The full-scale equipment comprised five propellers in combination with a VE-7 airplane and Wright E-4 engine. This part of the work was carried out at the Langley Memorial Aeronautical Laboratory, between May 1 and August 24, 1924, and was under the immediate charge of Mr. Lesley. The model or wind-tunnel part of the investigation was carried out at the Aerodynamic Laboratory of Stanford University and was under the immediate charge of Doctor Durand. A comparison of the curves for full-scale results with those derived from the model tests shows that while the efficiencies realized in flight are close to those derived from model tests, both thrust developed and power absorbed in flight are from 6 to 10 per cent greater than would be expected from the results of model tests.

  20. Model Test of Mars Entry Vehicles in Langley Spin Tunnel

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Model Test of Mars Entry Vehicles in Langley Spin Tunnel. Four models of Mars entry vehicles tested were a sphere with cg=35 percent (measured in percent of diameter from surface); Apollo with cg=16 percent (measured in percent of maximum diameter rearward of heat shield); a 103-degree cone with cg=20 percent (measured in percent of maximum diameter rearward of small end); and a tension structure: cg=25 percent (measured in percent of maximum diameter rearward of small end). [Entire movie available on DVD from CASI as Doc ID 20070030979. Contact help@sti.nasa.gov