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Sample records for autogenous shrinkage cracking

  1. Temperature dependence of autogenous shrinkage of silica fume cement pastes with a very low water–binder ratio

    SciTech Connect

    Maruyama, I.; Teramoto, A.

    2013-08-15

    Ultra-high-strength concrete with a large unit cement content undergoes considerable temperature increase inside members due to hydration heat, leading to a higher risk of internal cracking. Hence, the temperature dependence of autogenous shrinkage of cement pastes made with silica fume premixed cement with a water–binder ratio of 0.15 was studied extensively. Development of autogenous shrinkage showed different behaviors before and after the inflection point, and dependence on the temperature after mixing and subsequent temperature histories. The difference in autogenous shrinkage behavior poses problems for winter construction because autogenous shrinkage may increase with decrease in temperature after mixing before the inflection point and with increase in temperature inside concrete members with large cross sections.

  2. Study on effects of solar radiation and rain on shrinkage, shrinkage cracking and creep of concrete

    SciTech Connect

    Asamoto, Shingo; Ohtsuka, Ayumu; Kuwahara, Yuta; Miura, Chikako

    2011-06-15

    In this paper, the effects of actual environmental actions on shrinkage, creep and shrinkage cracking of concrete are studied comprehensively. Prismatic specimens of plain concrete were exposed to three sets of artificial outdoor conditions with or without solar radiation and rain to examine the shrinkage. For the purpose of studying shrinkage cracking behavior, prismatic concrete specimens with reinforcing steel were also subjected to the above conditions at the same time. The shrinkage behavior is described focusing on the effects of solar radiation and rain based on the moisture loss. The significant environment actions to induce shrinkage cracks are investigated from viewpoints of the amount of the shrinkage and the tensile strength. Finally, specific compressive creep behavior according to solar radiation and rainfall is discussed. It is found that rain can greatly inhibit the progresses of concrete shrinkage and creep while solar radiation is likely to promote shrinkage cracking and creep.

  3. Self-healing of drying shrinkage cracks in cement-based materials incorporating reactive MgO

    NASA Astrophysics Data System (ADS)

    Qureshi, T. S.; Al-Tabbaa, A.

    2016-08-01

    Excessive drying shrinkage is one of the major issues of concern for longevity and reduced strength performance of concrete structures. It can cause the formation of cracks in the concrete. This research aims to improve the autogenous self-healing capacity of traditional Portland cement (PC) systems, adding expansive minerals such as reactive magnesium oxide (MgO) in terms of drying shrinkage crack healing. Two different reactive grades (high ‘N50’and moderately high ‘92-200’) of MgO were added with PC. Cracks were induced in the samples with restraining end prisms through natural drying shrinkage over 28 days after casting. Samples were then cured under water for 28 and 56 days, and self-healing capacity was investigated in terms of mechanical strength recovery, crack sealing efficiency and improvement in durability. Finally, microstructures of the healing materials were investigated using FT-IR, XRD, and SEM-EDX. Overall N50 mixes show higher expansion and drying shrinkage compared to 92-200 mixes. Autogenous self-healing performance of the MgO containing samples were much higher compared to control (only PC) mixes. Cracks up to 500 μm were sealed in most MgO containing samples after 28 days. In the microstructural investigations, highly expansive Mg-rich hydro-carbonate bridges were found along with traditional calcium-based, self-healing compounds (calcite, portlandite, calcium silicate hydrates and ettringite).

  4. Evaluation of shrinkage and cracking in concrete of ring test by acoustic emission method

    NASA Astrophysics Data System (ADS)

    Watanabe, Takeshi; Hashimoto, Chikanori

    2015-03-01

    Drying shrinkage of concrete is one of the typical problems related to reduce durability and defilation of concrete structures. Lime stone, expansive additive and low-heat Portland cement are used to reduce drying shrinkage in Japan. Drying shrinkage is commonly evaluated by methods of measurement for length change of mortar and concrete. In these methods, there is detected strain due to drying shrinkage of free body, although visible cracking does not occur. In this study, the ring test was employed to detect strain and age cracking of concrete. The acoustic emission (AE) method was adopted to detect micro cracking due to shrinkage. It was recognized that in concrete using lime stone, expansive additive and low-heat Portland cement are effective to decrease drying shrinkage and visible cracking. Micro cracking due to shrinkage of this concrete was detected and evaluated by the AE method.

  5. Development of high shrinkage polyethylene terephthalate (PET) shape memory polymer tendons for concrete crack closure

    NASA Astrophysics Data System (ADS)

    Teall, Oliver; Pilegis, Martins; Sweeney, John; Gough, Tim; Thompson, Glen; Jefferson, Anthony; Lark, Robert; Gardner, Diane

    2017-04-01

    The shrinkage force exerted by restrained shape memory polymers (SMPs) can potentially be used to close cracks in structural concrete. This paper describes the physical processing and experimental work undertaken to develop high shrinkage die-drawn polyethylene terephthalate (PET) SMP tendons for use within a crack closure system. The extrusion and die-drawing procedure used to manufacture a series of PET tendon samples is described. The results from a set of restrained shrinkage tests, undertaken at differing activation temperatures, are also presented along with the mechanical properties of the most promising samples. The stress developed within the tendons is found to be related to the activation temperature, the cross-sectional area and to the draw rate used during manufacture. Comparisons with commercially-available PET strip samples used in previous research are made, demonstrating an increase in restrained shrinkage stress by a factor of two for manufactured PET filament samples.

  6. Measurement of shrinkage and cracking in lyophilized amorphous cakes. Part IV: Effects of freezing protocol.

    PubMed

    Ullrich, Sabine; Seyferth, Stefan; Lee, Geoffrey

    2015-11-10

    The shrinkage and cracking of pure trehalose cakes during lyophilization has been determined quantitatively using different protocols for the freezing step. The influences of shelf cooling rate and of a two-step freezing protocol with holding and annealing phases were investigated. A small change in the shelf cooling rate from 0.4°C to 0.2°C per minute produced surprisingly large increases in shrinkage and reductions in cracking over all trehalose concentrations up to 30% w/v. The two-step freezing protocol also increased shrinkage and reduced cracking in the final-product cakes, especially at trehalose concentrations ≥ 15% and with large vial fill height. A combination of two-step freezing with use of TopLyo vials produced less than 1.5% cracking even at high trehalose concentrations and large fill height. The results give further confirmation of the causal linkage of shrinkage and cracking during lyophilization, and also illustrate how cracking can be greatly reduced by manipulating the freezing protocol.

  7. Assessment and prediction of drying shrinkage cracking in bonded mortar overlays

    SciTech Connect

    Beushausen, Hans Chilwesa, Masuzyo

    2013-11-15

    Restrained drying shrinkage cracking was investigated on composite beams consisting of substrate concrete and bonded mortar overlays, and compared to the performance of the same mortars when subjected to the ring test. Stress development and cracking in the composite specimens were analytically modeled and predicted based on the measurement of relevant time-dependent material properties such as drying shrinkage, elastic modulus, tensile relaxation and tensile strength. Overlay cracking in the composite beams could be very well predicted with the analytical model. The ring test provided a useful qualitative comparison of the cracking performance of the mortars. The duration of curing was found to only have a minor influence on crack development. This was ascribed to the fact that prolonged curing has a beneficial effect on tensile strength at the onset of stress development, but is in the same time not beneficial to the values of tensile relaxation and elastic modulus. -- Highlights: •Parameter study on material characteristics influencing overlay cracking. •Analytical model gives good quantitative indication of overlay cracking. •Ring test presents good qualitative indication of overlay cracking. •Curing duration has little effect on overlay cracking.

  8. Effect of multivalent ions on the swelling and mechanical behavior of superabsorbent polymers (SAPs) for mitigation of mortar autogenous shrinkage

    NASA Astrophysics Data System (ADS)

    Zhu, Qian

    The chemical and physical structure-property relationships of model superabsorbent polymer (SAP) hydrogels were characterized with respect to swelling behavior and mechanical properties in different ionic solutions (Na+, Ca2+, and Al3+). The model hydrogels were composed of poly(sodium acrylate-acrylamide) (PANa-PAM) copolymer with varying concentrations of PANa (0, 17, 33, 67, and 83 wt.%) and covalent crosslinking densities of 1, 1.5, and 2 wt.%. By synthesizing the hydrogels in-house, systems with independently tunable amounts of covalent crosslinking and anionic functional groups were created, allowing for the relative effects of covalent and ionic crosslinking on the properties of the hydrogels to be directly quantified. It was found that the presence of Ca2+ and Al3+ in the absorbed fluid significantly decreased the swelling capacity and altered the swelling kinetics of the PANa-PAM hydrogels. The presence of Al 3+ in solution resulted in the unexpected formation of a mechanically stiff barrier layer at the hydrogel's surface, which hindered the release of fluid and caused the overall elastic modulus of the hydrogel to increase from O(10 kPa) for hydrogels immersed in Ca2+ solutions to O(100 kPa) for hydrogels immersed in Al3+ solutions. Tensile tests performed on isolated specimens of the stiff barrier layer yielded elastic moduli in the O(50-100 MPa) range. Further experiments proved that PANa-PAM hydrogels are effective to keep mortar internal relative humidity at high value (~98%) during setting and also PANa-PAM decreased the autogenous shrinkage of mortar to less than 50 microstrain while plain mortar showed 350 microstrain.

  9. Development and construction of low-cracking high-performance concrete (LC-HPC) bridge decks: Free shrinkage tests, restrained ring tests, construction experience, and crack survey results

    NASA Astrophysics Data System (ADS)

    Yuan, Jiqiu

    2011-12-01

    The development, construction, and evaluation of low-cracking high-performance concrete (LC-HPC) bridge decks are described based on laboratory test results and experiences gained during the construction of 13 LC-HPC bridge decks in Kansas, along with another deck bid under the LC-HPC specifications but for which the owner did not enforce the specification. This study is divided into four parts covering (1) an evaluation of the free shrinkage properties of LC-HPC candidate mixtures, (2) an investigation of the relationship between the evaporable water content in the cement paste and the free shrinkage of concrete, (3) a study of the restrained shrinkage performance of concrete using restrained ring tests, and (4) a description of the construction and preliminary evaluation of LC-HPC and control bridge decks constructed in Kansas. The first portion of the study involves evaluating the effects of the duration of curing, fly ash, and a shrinkage reducing admixture (SRA) on the free-shrinkage characteristics of concrete mixtures. The results indicate that an increase of curing period reduces free shrinkage. With 7 days of curing, concretes containing fly ash as a partial replacement for cement exhibit higher free shrinkage than concretes with 100% portland cement. When the curing period is increased to 14, 28, and 56 days, the adverse effect of adding fly ash on free shrinkage is minimized and finally reversed. The addition of an SRA significantly reduces free shrinkage for both the 100% portland cement mixture and the mixture containing fly ash. The second portion of the study investigates the relationship between the evaporable water content in the cement paste and the free shrinkage of concrete. A linear relationship between free shrinkage and evaporable water content in the cement paste is observed. For a given mixture, specimens cured for a longer period contain less evaporable water and exhibit lower free shrinkage and less weight loss in the free shrinkage

  10. Measurement of shrinkage and cracking in lyophilized amorphous cakes, part 3: hydrophobic vials and the question of adhesion.

    PubMed

    Ullrich, Sabine; Seyferth, Stefan; Lee, Geoffrey

    2015-06-01

    The importance of cake adhesion to the inside vial wall during lyophilization of amorphous trehalose cakes was determined by using hydrophobized vials. The degrees of cake shrinkage and cracking were determined independently by photographic imaging of the cake top surface in a dark cell. Additionally, measurements with microcomputed tomography were performed. Adhesion is found to be a determining factor in both cake shrinkage and cracking. The correlation between cake detachment from the vial inner wall and trehalose concentration indicates that adhesion of the frozen solute phase is a determining factor in shrinkage. The hydrophobized vials give reduced cracking at trehalose concentrations of up to 15%. The reduced wetting of the hydrophobized inside vial wall gives a planar cake topography with a uniform distribution of cracks within the cake.

  11. Shrinkage Cracking: A mechanism for self-sustaining carbon mineralization reactions in olivine rocks

    NASA Astrophysics Data System (ADS)

    Zhu, W.; Fusseis, F.; Lisabeth, H. P.; Xing, T.; Xiao, X.; De Andrade, V. J. D.; Karato, S. I.

    2015-12-01

    The hydration and carbonation of olivine results in an up to ~44% increase in solid molar volume, which may choke off of fluid supply and passivate reactive surfaces, thus preventing further carbonation reactions. The carbonation of olivine has ben studied extensively in the laboratory. To date, observations from these experimental studies indicate that carbonation reaction rates generally decrease with time and the extent of carbonation is limited in olivine rocks. Field studies, however, show that 100% hydration and carbonation occur naturally in ultramafic rocks. The disagreement between the laboratory results under controlled conditions and the field observations underlines the lack of understanding of the mechanisms responsible for the self-sustaining carbonation interaction in nature. We developed a state-of-the-art pressurized hydrothermal cell that is transparent to X-rays to characterize the real-time evolution of pore geometry during fluid-rock interaction using in-situ synchrotron-based X-ray microtomography. Through a time series of high-resolution 3-dimensional images, we document the microstructural evolution of a porous olivine aggregate reacting with a sodium bicarbonate solution at elevated pressure and temperature conditions. We observed porosity increases, near constant rate of crystal growth, and pervasive reaction-induced fractures. Based on the nanometer scale tomography data, we propose that shrinkage cracking is the mechanism responsible for producing new reactive surface and keep the carbonation reaction self-sustaining in our experiment. Shrinkage cracks are commonly observed in drying mud ponds, cooling lava flows and ice wedge fields. Stretching of a contracting surface bonded to a substrate of nearly constant dimensions leads to a stress buildup in the surface layer. When the stress exceeds the tensile strength, polygonal cracks develop in the surface layer. In our experiments, the stretching mismatch between the surface and interior of

  12. Field Method for Measuring the Shrinkage/Swelling Dynamics of Cracks Using a Low-Cost ``Crack-o-meter''

    NASA Astrophysics Data System (ADS)

    Stewart, R. D.; Abou Najm, M. R.; Rupp, D. E.; Selker, J. S.

    2010-12-01

    Shrinking/swelling soils are characterized by transient crack networks which function as dominant controls on the partitioning of surface and subsurface flow, the rate and depth of percolation, and evaporation rates. For such soils, understanding the dynamics of cracks is critical to accurately quantify their influence on groundwater recharge, stream-flow generation, and solute transport, among other component of a site’s hydrology. We propose a low-cost method for measuring transient crack-volume using a sealed plastic bag connected by a hose to a PVC standpipe. The empty bag is placed into the crack, and then water is added via the standpipe, until the bag has expanded to the boundaries of the crack and some water remains in the standpipe. As the crack shrinks or swells, its volume changes, causing water displacement within the bag, which is measured as a corresponding change in water level in the standpipe. An automated level logger within the standpipe is used to record changes in water level, which are converted to volumetric changes from the known internal cross-sectional area of the standpipe. The volume of water filling the bag is accurately measured at the start and completion of the experiment (to check for leakage). Adding the startup volume to the cumulative temporal volumetric change in the standpipe provides a simple and accurate method for monitoring transient crack volume. Currently, the design is undergoing preliminary testing in a field site in Ninhue, Chile, and field and laboratory testing in Corvallis, Oregon. Initial results from the Chilean field site suggest that the crack-o-meters are responding to the closing of cracks, but further effort is needed to calibrate and validate the results. We hope that these low-cost “crack-o-meters” will become useful and simple tools for researchers to quantify temporal changes in crack volume with the objective of incorporating these results into hydrological modeling efforts.

  13. Autogenic training.

    PubMed

    Benor, R

    1996-10-01

    Westernized medicine has conditioned us to rely on the outer physician; Autogenic Training (AT) enables us to find and develop an intimate relationship with our own inner physician and healer. This article outlines the historical and theoretical background to AT. The training process is described and reference is made to research literature which illustrates those individuals, illnesses, and conditions which respond favourably to AT. Drawing on the current mind-body science of Psychoneuroimmunology (PNI), AT is seen as a significant member of the growing body of PNI techniques, research, and complementary therapies in the UK.

  14. A new system for crack closure of cementitious materials using shrinkable polymers

    SciTech Connect

    Jefferson, Anthony; Joseph, Christopher; Lark, Robert; Isaacs, Ben; Dunn, Simon; Weager, Brendon

    2010-05-15

    This paper presents details of an original crack-closure system for cementitious materials using shrinkable polymer tendons. The system involves the incorporation of unbonded pre-oriented polymer tendons in cementitious beams. Crack closure is achieved by thermally activating the shrinkage mechanism of the restrained polymer tendons after the cement-based material has undergone initial curing. The feasibility of the system is demonstrated in a series of small scale experiments on pre-cracked prismatic mortar specimens. The results from these tests show that, upon activation, the polymer tendon completely closes the preformed macro-cracks and imparts a significant stress across the crack faces. The potential of the system to enhance the natural autogenous crack healing process and generally improve the durability of concrete structures is addressed.

  15. Analysis, prediction, and case studies of early-age cracking in bridge decks

    NASA Astrophysics Data System (ADS)

    ElSafty, Adel; Graeff, Matthew K.; El-Gharib, Georges; Abdel-Mohti, Ahmed; Mike Jackson, N.

    2016-06-01

    Early-age cracking can adversely affect strength, serviceability, and durability of concrete bridge decks. Early age is defined as the period after final setting, during which concrete properties change rapidly. Many factors can cause early-age bridge deck cracking including temperature change, hydration, plastic shrinkage, autogenous shrinkage, and drying shrinkage. The cracking may also increase the effect of freeze and thaw cycles and may lead to corrosion of reinforcement. This research paper presents an analysis of causes and factors affecting early-age cracking. It also provides a tool developed to predict the likelihood and initiation of early-age cracking of concrete bridge decks. Understanding the concrete properties is essential so that the developed tool can accurately model the mechanisms contributing to the cracking of concrete bridge decks. The user interface of the implemented computer Excel program enables the user to input the properties of the concrete being monitored. The research study and the developed spreadsheet were used to comprehensively investigate the issue of concrete deck cracking. The spreadsheet is designed to be a user-friendly calculation tool for concrete mixture proportioning, temperature prediction, thermal analysis, and tensile cracking prediction. The study also provides review and makes recommendations on the deck cracking based mainly on the Florida Department of Transportation specifications and Structures Design Guidelines, and Bridge Design Manuals of other states. The results were also compared with that of other commercially available software programs that predict early-age cracking in concrete slabs, concrete pavement, and reinforced concrete bridge decks. The outcome of this study can identify a set of recommendations to limit the deck cracking problem and maintain a longer service life of bridges.

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    MedlinePlus

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    MedlinePlus

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  18. Autogen Version 2.0

    NASA Technical Reports Server (NTRS)

    Gladden, Roy

    2007-01-01

    Version 2.0 of the autogen software has been released. "Autogen" (automated sequence generation) signifies both a process and software used to implement the process of automated generation of sequences of commands in a standard format for uplink to spacecraft. Autogen requires fewer workers than are needed for older manual sequence-generation processes and reduces sequence-generation times from weeks to minutes.

  19. Veterinary autogenous vaccines.

    PubMed

    Hera, A; Bures, J

    2004-01-01

    Autogenous vaccines remain a regulatory issue. They are demanded by practising veterinarians and by animal owners and they are quite widely used, mainly in Central European Countries, the Czech Republic, Hungary and Slovak Republic having probably the longest tradition with these products in Central Europe. The scope given in Article 3, Para. 2 (and/or Article 4 for some countries) of Directive 2001/82/EC applies to these products in the Acceding Countries. As these products are exempt from the harmonised regulation at the EU level, they are regulated by individual countries, the regulation varying from practically no regulatory measures in certain countries to a quite complex and demanding regulation in the other countries. Both risks and benefits are related to these products and they shall be taken into account when regulatory measures are considered. The major risks related to veterinary autogenous vaccines relate to possibility of transmission of TSE agents or other viral, bacterial and/or fungal contaminants. As appropriate and well balanced regulation of these products is deemed necessary, considering the risks related to these products, and based on the fact that national regulatory measures could be considered as a trade barrier under certain circumstances, harmonisation of the key issues or legal admission of the nationally based regulatory measures, including movement of these products from the other Member States, shall be laid down in the EU legislation. The veterinary autogenous vaccines complying with basic quality and safety requirements are thus a very useful tool in the animal health and welfare management but their use should be restricted to situations where there is no authorised veterinary medicinal product available and veterinary autogenous vaccines must not be allowed to replace good farming or veterinary practices.

  20. PLASTIC SHRINKAGE CONTROLLING EFFECT BY POLYPROPYLENE SHORT FIBER WITH HYDROPHILY

    NASA Astrophysics Data System (ADS)

    Hosoda, Akira; Sadatsuki, Yoshitomo; Oshima, Akihiro; Ishii, Akina; Tsubaki, Tatsuya

    The aim of this research is to clarify the mechanism of controlling plastic shrinkage crack by adding small amout of synthetic short fiber, and to propose optimum polypropylene short fiber to control plastic shrinkage crack. In this research, the effect of the hydrophily of polypropylene fiber was investigated in the amount of plastic shrinkage of mortar, total area of plastic shrinkage crack, and bond properties between fiber and mortar. The plastic shrinkage test of morar was conducted under high temperature, low relative humidity, and constant wind velocity. When polypropylene fiber had hydrophily, the amount of plastic shrinkage of mortar was restrained, which was because cement paste in morar was captured by hydrophilic fiber and then bleeding of mortar was restrained. With hydrophily, plastic shrinkage of mortar was restrained and bridging effect was improved due to better bond, which led to remarkable reduction of plastic shrinkage crack. Based on experimental results, the way of developing optimum polypropylene short fiber for actual construction was proposed. The fiber should have large hydrophily and small diameter, and should be used in as small amount as possible in order not to disturb workability of concrete.

  1. Autogenic training and dream recall.

    PubMed

    Schredl, M; Doll, E

    1997-06-01

    The present study has investigated the relationship between Autogenic Training and dream recall for 112 participants in 16 beginning courses of 10 wk. Analyses confirmed the hypothesis that learning and practicing this relaxation technique enhanced dream recall.

  2. New methods to quantify the cracking performance of cementitious systems made with internal curing

    NASA Astrophysics Data System (ADS)

    Schlitter, John L.

    which is located outside of the sample to provide restraint against expansion. Second, the standard ring test is a passive test that only relies on the autogenous and drying shrinkage of the mixture to induce cracking. The dual ring test can be an active test because it has the ability to vary the temperature of the specimen in order to induce thermal stress and produce cracking. This ability enables the study of the restrained cracking capacity as the mixture ages in order to quantify crack sensitive periods of time. Measurements made with the dual ring quantify the benefits from using larger amounts of internal curing. Mixtures that resupplied internal curing water to match that of chemical shrinkage could sustain three times the magnitude of thermal change before cracking. The second device discussed in this thesis is a large scale slab testing device. This device tests the cracking potential of 15' long by 4" thick by 24" wide slab specimens in an environmentally controlled chamber. The current standard testing devices can be considered small scale and encounter problems when linking their results to the field due to size effects. Therefore, the large scale slab testing device was developed in order to calibrate the results of smaller scale tests to real world field conditions such as a pavement or bridge deck. Measurements made with the large scale testing device showed that the cracking propensity of the internally cured mixtures was reduced and that a significant benefit could be realized.

  3. Comparison of shrinkage related properties of various patch repair materials

    NASA Astrophysics Data System (ADS)

    Kristiawan, S. A.; Fitrianto, R. S.

    2017-02-01

    A patch repair material has been developed in the form of unsaturated polyester resin (UPR)-mortar. The performance and durability of this material are governed by its compatibility with the concrete being repaired. One of the compatibility issue that should be tackled is the dimensional compatibility as a result of differential shrinkage between the repair material and the concrete substrate. This research aims to evaluate such shrinkage related properties of UPR-mortar and to compare with those of other patch repair materials. The investigation includes the following aspects: free shrinkage, resistance to delamination and cracking. The results indicate that UPR-mortar poses a lower free shrinkage, lower risk of both delamination and cracking tendency in comparison to other repair materials.

  4. Comment on autogenic training and hypertension.

    PubMed

    Sakai, M; Sato, T; Takeichi, M; Fakunishi, I

    1997-06-01

    We comment on a report by Watanabe, et al. regarding the effects of autogenic training on hypertension. Using previous reports in the United States, we mention methodological problems on how to evaluate the effects of autogenic training and express our hope that they would provide further research to clarify the effects of autogenic training on hypertension.

  5. Kinetics of corneal thermal shrinkage

    NASA Astrophysics Data System (ADS)

    Borja, David; Manns, Fabrice; Lee, William E.; Parel, Jean-Marie

    2004-07-01

    Purpose: The purpose of this study was to determine the effects of temperature and heating duration on the kinetics of thermal shrinkage in corneal strips using a custom-made shrinkage device. Methods: Thermal shrinkage was induced and measured in corneal strips under a constant load placed while bathed in 25% Dextran irrigation solution. A study was performed on 57 Florida Lions Eye Bank donated human cadaver eyes to determine the effect of temperature on the amount and rate of thermal shrinkage. Further experiments were performed on 20 human cadaver eyes to determine the effects of heating duration on permanent shrinkage. Data analysis was performed to determine the effects of temperature, heating duration, and age on the amount and kinetics of shrinkage. Results: Shrinkage consisted of two phases: a shrinkage phase during heating and a regression phase after heating. Permanent shrinkage increased with temperature and duration. The shrinkage and regression time constants followed Arrhenius type temperature dependence. The shrinkage time constants where calculated to be 67, 84, 121, 560 and 1112 (s) at 80, 75, 70, 65, and 60°C respectively. At 65°C the permanent shrinkage time constant was calculated to be 945s. Conclusion: These results show that shrinkage treatments need to raise the temperature of the tissue above 75°C for several seconds in order to prevent regression of the shrinkage effect immediately after treatment and to induce the maximum amount of permanent irreversible shrinkage.

  6. Roof System EPDM Shrinkage.

    ERIC Educational Resources Information Center

    Betker, Edward

    1998-01-01

    Looks at Ethylene Propylene Diene Terpolymer rubber roof membranes and the potential problems associated with this material's shrinkage. Discusses how long such a roof should perform and issues affecting repair or replacement. Recommends that a building's function be considered in any roofing decision. (RJM)

  7. Cure shrinkage in casting resins

    SciTech Connect

    Spencer, J. Brock

    2015-02-01

    A method is described whereby the shrinkage of a casting resin can be determined. Values for the shrinkage of several resin systems in frequent use by Sandia have been measured. A discussion of possible methods for determining the stresses generated by cure shrinkage and thermal contraction is also included.

  8. Development of spraying agent for reducing drying shrinkage of mortar

    NASA Astrophysics Data System (ADS)

    Fujiwara, Hiromi; Maruoka, Masanori; Liu, Lingling

    2017-02-01

    Mortar used to repair is sometimes exposed to drying state in early ages after construction and a few days later water is sprayed frequently on the surface of the mortar in order to prevent cracks. This research studied on shrinkage characteristic of mortar subjected to drying conditions like this. The result showed that the water spraying on the mortar after initial drying did not have any effect to prevent shrinkage, but increased. And it also showed when various chemical agents are mixed and used in watersprayingit had the prevention effect on shrinkage. This report was to understand this kind of phenomenon and clarify the mechanism. In addition, based on the results, the new spraying agent was developed to reduce drying shrinkage.

  9. AutoGen Version 5.0

    NASA Technical Reports Server (NTRS)

    Gladden, Roy E.; Khanampornpan, Teerapat; Fisher, Forest W.

    2010-01-01

    Version 5.0 of the AutoGen software has been released. Previous versions, variously denoted Autogen and autogen, were reported in two articles: Automated Sequence Generation Process and Software (NPO-30746), Software Tech Briefs (Special Supplement to NASA Tech Briefs), September 2007, page 30, and Autogen Version 2.0 (NPO- 41501), NASA Tech Briefs, Vol. 31, No. 10 (October 2007), page 58. To recapitulate: AutoGen (now signifying automatic sequence generation ) automates the generation of sequences of commands in a standard format for uplink to spacecraft. AutoGen requires fewer workers than are needed for older manual sequence-generation processes, and greatly reduces sequence-generation times. The sequences are embodied in spacecraft activity sequence files (SASFs). AutoGen automates generation of SASFs by use of another previously reported program called APGEN. AutoGen encodes knowledge of different mission phases and of how the resultant commands must differ among the phases. AutoGen also provides means for customizing sequences through use of configuration files. The approach followed in developing AutoGen has involved encoding the behaviors of a system into a model and encoding algorithms for context-sensitive customizations of the modeled behaviors. This version of AutoGen addressed the MRO (Mars Reconnaissance Orbiter) primary science phase (PSP) mission phase. On previous Mars missions this phase has more commonly been referred to as mapping phase. This version addressed the unique aspects of sequencing orbital operations and specifically the mission specific adaptation of orbital operations for MRO. This version also includes capabilities for MRO s role in Mars relay support for UHF relay communications with the MER rovers and the Phoenix lander.

  10. Plastic shrinkage of mortars with shrinkage reducing admixture and lightweight aggregates studied by neutron tomography

    SciTech Connect

    Wyrzykowski, Mateusz; Trtik, Pavel; Münch, Beat; Weiss, Jason; Vontobel, Peter; Lura, Pietro

    2015-07-15

    Water transport in fresh, highly permeable concrete and rapid water evaporation from the concrete surface during the first few hours after placement are the key parameters influencing plastic shrinkage cracking. In this work, neutron tomography was used to determine both the water loss from the concrete surface due to evaporation and the redistribution of fluid that occurs in fresh mortars exposed to external drying. In addition to the reference mortar with a water to cement ratio (w/c) of 0.30, a mortar with the addition of pre-wetted lightweight aggregates (LWA) and a mortar with a shrinkage reducing admixture (SRA) were tested. The addition of SRA reduced the evaporation rate from the mortar at the initial stages of drying and reduced the total water loss. The pre-wetted LWA released a large part of the absorbed water as a consequence of capillary pressure developing in the fresh mortar due to evaporation.

  11. Store Security: Internal Shrinkage Control.

    ERIC Educational Resources Information Center

    Everhardt, Richard M.

    The document presents a 10-week training program designed to provide helpful and proven methods for controlling internal shrinkage in retail stores. Shrinkage includes the three problems of shoplifting, employee theft, and errors, each of which is addressed by the course. Ohio's laws are also discussed. The format for the course content section is…

  12. Documenting AUTOGEN and APGEN Model Files

    NASA Technical Reports Server (NTRS)

    Gladden, Roy E.; Khanampompan, Teerapat; Fisher, Forest W.; DelGuericio, Chris c.

    2008-01-01

    A computer program called "autogen hypertext map generator" satisfies a need for documenting and assisting in visualization of, and navigation through, model files used in the AUTOGEN and APGEN software mentioned in the two immediately preceding articles. This program parses autogen script files, autogen model files, PERL scripts, and apgen activity-definition files and produces a hypertext map of the files to aid in the navigation of the model. This program also provides a facility for adding notes and descriptions, beyond what is in the source model represented by the hypertext map. Further, this program provides access to a summary of the model through variable, function, sub routine, activity and resource declarations as well as providing full access to the source model and source code. The use of the tool enables easy access to the declarations and the ability to traverse routines and calls while analyzing the model.

  13. Early age stresses and creep-shrinkage interaction of restrained concrete

    NASA Astrophysics Data System (ADS)

    Altoubat, Salah Ahmed

    2000-10-01

    Experimental and numerical analyses were performed to characterize the early age tensile creep and shrinkage behavior of concrete. A uniaxial restrained shrinkage test was developed. The experiment tested two identical specimens: restrained and unrestrained. The test was controlled by computer, and the shrinkage deformation was checked continuously and compared to a threshold value of 5 mum, which when exceeded, triggered an increase in tensile load to recover the shrinkage strain in the restrained specimen. Thus, a restrained condition is achieved and the stress generated by shrinkage mechanisms was measurable. The experiment revealed how shrinkage stresses developed and how creep mechanisms reduced shrinkage strain. The tests revealed that shrinkage stresses in the first days after casting are significant and caused fracture of the concrete. The rate of stress evolution influenced the time and stress of first cracking. The tensile creep of concrete formed a substantial part of the time dependent deformation and reduced the shrinkage stresses by 50%. A method separating drying creep mechanisms of concrete into stress-induced shrinkage and microcracking was developed. The method required measurement of creep and shrinkage of concrete under drying, sealed, and moist curing conditions. The moist-curing test produce the basic creep; the sealed test provided data on basic creep and stress-induced shrinkage, and the drying test provided data on basic creep, stress-induced shrinkage and microcracking. The basic creep results of young concrete indicated a high creep rate in the initial 10--20 hours after loading. Then, the rate decreased and the creep function approached a stable value. The initial rate of creep was sensitive to age at loading in the first two days, and became age-independent after a few days. The analysis revealed stress-induced shrinkage as a major mechanism of drying creep for plain and fiber reinforced concrete (FRC). Microcracking forms a significant

  14. A novel two-dimensional method to measure surface shrinkage in cementitious materials

    SciTech Connect

    Chen, T.C.; Ferraro, C.C.; Yin, W.Q.; Ishee, C.A.; Ifju, P.G.

    2010-05-15

    A novel experimental technique, Cure Reference Method (CRM), was developed for the measurement of surface shrinkage in cementitious materials. The technique combines the replication of diffraction grating on a specimen during the curing process and the use of high-sensitivity moire interferometry. Once demolded, the specimen was stored in an environmental chamber in order to establish specific curing conditions. Measurements were conducted on a daily basis for the duration of 7 days by recording a set of the consecutive phase shifted fringe patterns using the Portable Engineering Moire interferometer II (PEMI II). An automated fringe analysis system was developed and used to obtain displacement and strain information in two dimenzsions. Surface shrinkage behavior in both cement paste and mortar specimens was investigated by the use of the technique under controlled temperature and humidity conditions. Furthermore, an experimental control was developed in an effort to remove the effects of drying shrinkage on cementitious specimens at early ages. This was done in an effort to explore the relative contribution of autogenous shrinkage to the overall shrinkage in cementitious materials.

  15. 30 CFR 35.20 - Autogenous-ignition temperature test.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Autogenous-ignition temperature test. 35.20... Autogenous-ignition temperature test. (a) Purpose. The purpose of this test, referred to hereinafter as the ignition-temperature test, is to determine the lowest autogenous-ignition temperature of a hydraulic...

  16. 30 CFR 35.20 - Autogenous-ignition temperature test.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Autogenous-ignition temperature test. 35.20... Autogenous-ignition temperature test. (a) Purpose. The purpose of this test, referred to hereinafter as the ignition-temperature test, is to determine the lowest autogenous-ignition temperature of a hydraulic...

  17. 30 CFR 35.20 - Autogenous-ignition temperature test.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Autogenous-ignition temperature test. 35.20... Autogenous-ignition temperature test. (a) Purpose. The purpose of this test, referred to hereinafter as the ignition-temperature test, is to determine the lowest autogenous-ignition temperature of a hydraulic...

  18. 30 CFR 35.20 - Autogenous-ignition temperature test.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Autogenous-ignition temperature test. 35.20... Autogenous-ignition temperature test. (a) Purpose. The purpose of this test, referred to hereinafter as the ignition-temperature test, is to determine the lowest autogenous-ignition temperature of a hydraulic...

  19. 30 CFR 35.20 - Autogenous-ignition temperature test.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Autogenous-ignition temperature test. 35.20... Autogenous-ignition temperature test. (a) Purpose. The purpose of this test, referred to hereinafter as the ignition-temperature test, is to determine the lowest autogenous-ignition temperature of a hydraulic...

  20. Management of pain through autogenic training.

    PubMed

    Kanji, N

    2000-08-01

    Physical and emotional pain are an inevitable part of human existence and are without natural antidotes. In view of this, and in the light of increasing professional reluctance to depend on analgesics, this paper proposes the widespread application of autogenic training, a relaxation technique which has been seen to confront pain very effectively, and also to reduce substantially drugs dependency. It analyses autogenic training in respect of some of the more common pain-allied disorders such as childbirth, headaches and migraines, back pain, cancer and palliative care, and cardiology.

  1. The origin of early age expansions induced in cementitious materials containing shrinkage reducing admixtures

    SciTech Connect

    Sant, Gaurav; Lothenbach, Barbara; Juilland, Patrick; Le Saout, Gwenn; Weiss, Jason; Scrivener, Karen

    2011-03-15

    Studies on the early-age shrinkage behavior of cement pastes, mortars, and concretes containing shrinkage reducing admixtures (SRAs) have indicated these mixtures frequently exhibit an expansion shortly after setting. While the magnitude of the expansion has been noted to be a function of the chemistry of the cement and the admixture dosage; the cause of the expansion is not clearly understood. This investigation uses measurements of autogenous deformation, X-ray diffraction, pore solution analysis, thermogravimetry, and scanning electron microscopy to study the early-age properties and describe the mechanism of the expansion in OPC pastes made with and without SRA. The composition of the pore solution indicates that the presence of the SRA increases the portlandite oversaturation level in solution which can result in higher crystallization stresses which could lead to an expansion. This observation is supported by deformation calculations for the systems examined.

  2. 9 CFR 113.113 - Autogenous biologics.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...) Identification. All microorganisms used for the production of autogenous biologics shall be identified as follows: Bacteria, fungi, and mycoplasma shall be identified at least to genus and species. Viruses shall be... of origin. (iv) Identification of microorganism(s), at least to genus. (v) Diagnosis or...

  3. Autogenic dynamics of debris-flow fans

    NASA Astrophysics Data System (ADS)

    van den Berg, Wilco; de Haas, Tjalling; Braat, Lisanne; Kleinhans, Maarten

    2015-04-01

    Alluvial fans develop their semi-conical shape by cyclic avulsion of their geomorphologically active sector from a fixed fan apex. These cyclic avulsions have been attributed to both allogenic and autogenic forcings and processes. Autogenic dynamics have been extensively studied on fluvial fans through physical scale experiments, and are governed by cyclic alternations of aggradation by unconfined sheet flow, fanhead incision leading to channelized flow, channel backfilling and avulsion. On debris-flow fans, however, autogenic dynamics have not yet been directly observed. We experimentally created debris-flow fans under constant extrinsic forcings, and show that autogenic dynamics are a fundamental intrinsic process on debris-flow fans. We found that autogenic cycles on debris-flow fans are driven by sequences of backfilling, avulsion and channelization, similar to the cycles on fluvial fans. However, the processes that govern these sequences are unique for debris-flow fans, and differ fundamentally from the processes that govern autogenic dynamics on fluvial fans. We experimentally observed that backfilling commenced after the debris flows reached their maximum possible extent. The next debris flows then progressively became shorter, driven by feedbacks on fan morphology and flow-dynamics. The progressively decreasing debris-flow length caused in-channel sedimentation, which led to increasing channel overflow and wider debris flows. This reduced the impulse of the liquefied flow body to the flow front, which then further reduced flow velocity and runout length, and induced further in-channel sedimentation. This commenced a positive feedback wherein debris flows became increasingly short and wide, until the channel was completely filled and the apex cross-profile was plano-convex. At this point, there was no preferential transport direction by channelization, and the debris flows progressively avulsed towards the steepest, preferential, flow path. Simultaneously

  4. Development of early age shrinkage stresses in reinforced concrete bridge decks

    NASA Astrophysics Data System (ADS)

    William, Gergis W.; Shoukry, Samir N.; Riad, Mourad Y.

    2008-12-01

    This paper describes the instrumentation and data analysis of a reinforced concrete bridge deck constructed on 3-span continuous steel girders in Evansville, West Virginia. An instrumentation system consisting of 232 sensors is developed and implemented specifically to measure strains and temperature in concrete deck, strains in longitudinal and transverse rebars, the overall contraction and expansion of concrete deck, and crack openings. Data from all sensors are automatically collected every 30 minutes starting at the time of placing the concrete deck. Measured strain and temperature time-histories were used to calculate the stresses, which were processed to attenuate the thermal effects due to daily temperature changes and isolate the drying shrinkage component. The results indicated that most of concrete shrinkage occurs during the first three days. Under the constraining effects from stay-in-place forms and reinforcement, early age shrinkage leads to elevated longitudinal stress, which is the main factor responsible for crack initiation.

  5. Effect of the Key Mixture Parameters on Shrinkage of Reactive Powder Concrete

    PubMed Central

    Zubair, Ahmed

    2014-01-01

    Reactive powder concrete (RPC) mixtures are reported to have excellent mechanical and durability characteristics. However, such concrete mixtures having high amount of cementitious materials may have high early shrinkage causing cracking of concrete. In the present work, an attempt has been made to study the simultaneous effects of three key mixture parameters on shrinkage of the RPC mixtures. Considering three different levels of the three key mixture factors, a total of 27 mixtures of RPC were prepared according to 33 factorial experiment design. The specimens belonging to all 27 mixtures were monitored for shrinkage at different ages over a total period of 90 days. The test results were plotted to observe the variation of shrinkage with time and to see the effects of the key mixture factors. The experimental data pertaining to 90-day shrinkage were used to conduct analysis of variance to identify significance of each factor and to obtain an empirical equation correlating the shrinkage of RPC with the three key mixture factors. The rate of development of shrinkage at early ages was higher. The water to binder ratio was found to be the most prominent factor followed by cement content with the least effect of silica fume content. PMID:25050395

  6. Cure shrinkage of thermoset composites

    SciTech Connect

    Russell, J.D. )

    1993-01-01

    The shrinkage of thermoset composites during cure was studied using a volumetric dilatometer. The material systems studied were AS4 carbon fiber/Hercules' 3501-6 epoxy, IM7 carbon fiber/Hercules 8551-7A toughened epoxy and IM7 carbon fiber/BASF's 5250-4 bismaleimide. Shrinkage of the samples due to both polymerization and thermal expansion effects was seen. The volume changes of the materials during cure were then compared to results from dynamic mechanical analysis (DMA) and dielectric cure monitoring. Maximums in volume corresponded to minimums in storage and loss modulus from DMA and maximums in the dielectric loss factor. Resin shrinkage during the 177 deg C (350 F) hold corresponded to the onset of polymerization seen by the rapid increase in the storage modulus and the decrease in the dielectric loss factor response due to reduced ion mobility. These results show that volumetric dilatometry can be an effective tool in the development of materials processing strategies and can be useful in studying residual stresses in composites. 9 refs.

  7. Shrinkage modeling of concrete reinforced by palm fibres in hot dry environments

    NASA Astrophysics Data System (ADS)

    Akchiche, Hamida; Kriker, Abdelouahed

    2017-02-01

    The cement materials, such as concrete and conventional mortar present very little resistance to traction and cracking, these hydraulic materials which induces large withdrawals on materials and cracks in structures. The hot dry environments such as: the Saharan regions of Algeria, Indeed, concrete structures in these regions are very fragile, and present high shrinkage. Strengthening of these materials by fibers can provide technical solutions for improving the mechanical performance. The aim of this study is firstly, to reduce the shrinkage of conventional concrete with its reinforcement with date palm fibers. In fact, Algeria has an extraordinary resources in natural fibers (from Palm, Abaca, Hemp) but without valorization in practical areas, especially in building materials. Secondly, to model the shrinkage behavior of concrete was reinforced by date palm fibers. In the literature, several models for still fiber concrete were founded but few are offers for natural fiber concretes. To do so, a still fiber concretes model of YOUNG - CHERN was used. According to the results, a reduction of shrinkage with reinforcement by date palm fibers was showed. A good ability of molding of shrinkage of date palm reinforced concrete with YOUNG - CHERN Modified model was obtained. In fact, a good correlation between experimental data and the model data was recorded.

  8. Towards a better understanding of the cracking behavior in soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding and modeling shrinkage-induced cracks helps bridge the gap between flow problem in the laboratory and at the field. Modeling flow at the field scale with Darcian fluxes developed at the laboratory scales is challenged with preferential flows attributed to the cracking behavior of soils...

  9. Shrinkage approach for EEG covariance matrix estimation.

    PubMed

    Beltrachini, Leandro; von Ellenrieder, Nicolas; Muravchik, Carlos H

    2010-01-01

    We present a shrinkage estimator for the EEG spatial covariance matrix of the background activity. We show that such an estimator has some advantages over the maximum likelihood and sample covariance estimators when the number of available data to carry out the estimation is low. We find sufficient conditions for the consistency of the shrinkage estimators and results concerning their numerical stability. We compare several shrinkage schemes and show how to improve the estimator by incorporating known structure of the covariance matrix.

  10. Devitrification and shrinkage behavior of silica fibers

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, I.

    1972-01-01

    Devitrification and shrinkage of three batches of silica fibers were investigated in the temperature range of 1200 to 1350 C. Fibers with high water and impurity content devitrified rapidly to cristobalite and quartz and exhibited rapid, but the least amount of, shrinkage. A batch with low water and impurity content devitrified more slowly to cristobalite only and underwent severe shrinkage by the mechanism of viscous flow. A third batch of intermediate purity level and low water content devitrified at a moderate rate mainly to cristobalite but shrunk very rapidly. Completely devitrified silica fibers did not exhibit any further shrinkage.

  11. The versatile autogenous rib graft in septorhinoplasty.

    PubMed

    Sherris, D A; Kern, E B

    1998-01-01

    In the graft depleted revision rhinoplasty patient and the patient with major tissue needs, alternatives to septal and conchal cartilage grafts are needed. The costal cartilage graft and rib bone/costal cartilage combination graft are excellent alternatives. In this study 14 patients received 40 grafts from 20 autogenous ribs harvested during septorhinoplasty. Materials were harvested for use as septal replacement grafts, cantilevered grafts, dorsal onlay grafts, columellar struts, and tip grafts. Patient followup was 6 to 31 months, and no evidence of graft resorption or warpage was evident during that period. Complications of harvest were minimal, and harvest techniques are detailed.

  12. VOLUMETRIC POLYMERIZATION SHRINKAGE OF CONTEMPORARY COMPOSITE RESINS

    PubMed Central

    Nagem, Halim; Nagem, Haline Drumond; Francisconi, Paulo Afonso Silveira; Franco, Eduardo Batista; Mondelli, Rafael Francisco Lia; Coutinho, Kennedy Queiroz

    2007-01-01

    The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire) to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (á=0.05) was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01) and Definite (1.89±0.01) shrank significantly less than the other composite resins. SureFil (2.01±0.06), Filtek Z250 (1.99±0.03), and Fill Magic (2.02±0.02) presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation. PMID:19089177

  13. Compressed sensing recovery via nonconvex shrinkage penalties

    NASA Astrophysics Data System (ADS)

    Woodworth, Joseph; Chartrand, Rick

    2016-07-01

    The {{\\ell }}0 minimization of compressed sensing is often relaxed to {{\\ell }}1, which yields easy computation using the shrinkage mapping known as soft thresholding, and can be shown to recover the original solution under certain hypotheses. Recent work has derived a general class of shrinkages and associated nonconvex penalties that better approximate the original {{\\ell }}0 penalty and empirically can recover the original solution from fewer measurements. We specifically examine p-shrinkage and firm thresholding. In this work, we prove that given data and a measurement matrix from a broad class of matrices, one can choose parameters for these classes of shrinkages to guarantee exact recovery of the sparsest solution. We further prove convergence of the algorithm iterative p-shrinkage (IPS) for solving one such relaxed problem.

  14. Accounting for PDMS shrinkage when replicating structures

    NASA Astrophysics Data System (ADS)

    Hannibal Madsen, Morten; Feidenhans'l, Nikolaj A.; Hansen, Poul-Erik; Garnæs, Jørgen; Dirscherl, Kai

    2014-12-01

    Polydimethylsiloxane (PDMS) is a widely used material for fabrication of microfluidic devices and for replication of micro- and nanotextured surfaces. Shrinkage of PDMS in the fabrication process can lead to leaking devices and poor alignment of layers. However, corrections to the mold master are seldom applied to counteract the shrinkage of PDMS. Also, to perform metrological measurements using replica techniques one has to take the shrinkage into account. Thus we report a study of the shrinkage of PDMS with several different mixing ratios and curing temperatures. The shrinkage factor, with its associated uncertainty, for PDMS in the range 40 to 120 °C is provided. By applying this correction factor, it is possible to replicate structures with a standard uncertainty of less than 0.2% in lateral dimensions using typical curing temperatures and PDMS mixing ratios in the range 1:6 to 1:20 (agent:base).

  15. A cure shrinkage model for analyzing the stresses and strains in encapsulated assemblies

    SciTech Connect

    Chambers, R.S.; Lagasse, R.R.; Guess, T.R.; Plazek, D.J.; Bero, C.

    1992-12-31

    Electrical component assemblies are encapsulated to provide delicate parts with voltage isolation and protection against damage caused by shock, vibration, and harsh atmospheric environments. During cure, thermosetting resins shrink and harden simultaneously. If the natural deformation of the resin is constrained by adhesion to the mold or to relatively stiff embedded components, cure shrinkage stresses are generated in the encapsulant. Subsequent cooling or thermal cycling produces additional stresses that are caused by the mismatches in thermal strains among the materials in the encapsulated assembly. Although cure shrinkage stresses frequently are neglected because they are considerably smaller than thermal stresses, cure shrinkage stresses can cause delamination or fractures in the encapsulant, since the partially cured resin is not as tough as the fully cured material. Cracks generated during cure can compromise performance (e. g., permit dielectric breakdown), degrade a component`s protection, and grow under subsequent thermal cycling producing residual stresses that differ from those found in uncracked assemblies. 3 refs., 11 figs.

  16. A cure shrinkage model for analyzing the stresses and strains in encapsulated assemblies

    NASA Astrophysics Data System (ADS)

    Chambers, R. S.; Lagasse, R. R.; Guess, T. R.; Plazek, D. J.; Bero, C.

    Electrical component assemblies are encapsulated to provide delicate parts with voltage isolation and protection against damage caused by shock, vibration, and harsh atmospheric environments. During cure, thermosetting resins shrink and harden simultaneously. If the natural deformation of the resin is constrained by adhesion to the mold or to relatively stiff embedded components, cure shrinkage stresses are generated in the encapsulant. Subsequent cooling or thermal cycling produces additional stresses that are caused by the mismatches in thermal strains among the materials in the encapsulated assembly. Although cure shrinkage stresses frequently are neglected because they are considerably smaller than thermal stresses, cure shrinkage stresses can cause delamination or fractures in the encapsulant, since the partially cured resin is not as tough as the fully cured material. Cracks generated during cure can compromise performance (e.g., permit dielectric breakdown), degrade a component's protection, and grow under subsequent thermal cycling producing residual stresses that differ from those found in uncracked assemblies.

  17. A cure shrinkage model for analyzing the stresses and strains in encapsulated assemblies

    SciTech Connect

    Chambers, R.S.; Lagasse, R.R.; Guess, T.R. ); Plazek, D.J.; Bero, C. . Dept. of Materials Science and Engineering)

    1992-01-01

    Electrical component assemblies are encapsulated to provide delicate parts with voltage isolation and protection against damage caused by shock, vibration, and harsh atmospheric environments. During cure, thermosetting resins shrink and harden simultaneously. If the natural deformation of the resin is constrained by adhesion to the mold or to relatively stiff embedded components, cure shrinkage stresses are generated in the encapsulant. Subsequent cooling or thermal cycling produces additional stresses that are caused by the mismatches in thermal strains among the materials in the encapsulated assembly. Although cure shrinkage stresses frequently are neglected because they are considerably smaller than thermal stresses, cure shrinkage stresses can cause delamination or fractures in the encapsulant, since the partially cured resin is not as tough as the fully cured material. Cracks generated during cure can compromise performance (e. g., permit dielectric breakdown), degrade a component's protection, and grow under subsequent thermal cycling producing residual stresses that differ from those found in uncracked assemblies. 3 refs., 11 figs.

  18. [Autogenic training in psychophysiological preparation for parachute jumps].

    PubMed

    Reshetnikov, M M

    1978-01-01

    The efficiency of specific psychophysiological preparation--autogenic training--to parachute jumps was measured in two groups of cadets (test subjects and controls). Hetero- and autogenic training was carried out according to a scheme specially developed for this type of activity. The study of questionnaires and physiological data demonstrated that the specific psychophysiological preparation by means of autogenic training for a certain type of activity helped to develop active self-control over one's own state and emotions, alleviated tension, arrested adverse neurotic manifestations (sleep disturbances, depression, anxiety), contributed to the feeling of confidence in the successful completion of the jump and promoted positive tuning towards subsequent jumps.

  19. Autogenous Transplantation for Replacing a Hopeless Tooth

    PubMed Central

    Zakershahrak, Mehrsa; Moshari, Amirabbas; Vatanpour, Mehdi; Khalilak, Zohreh; Jalali Ara, Afsoon

    2017-01-01

    Autogenous tooth transplantation (ATT) is a simple and reasonable choice for replacing the missing teeth when a proper donor tooth is available. This report presents a case of successful ATT of a maxillary right third molar for replacement of mandibular right second molar with a concomitant endodontic-periodontal disease. The mandibular second molar was believed to be hopeless due to a severe damage to coronal tooth structure, inappropriate root canal treatment and apical radiolucency. After extraction of mandibular second molar and maxillary third molar (the donor), the tooth was re-implanted into the extracted socket of second molar site. Root canal therapy was then performed. After 3 years, clinical and radiographic examinations revealed satisfying results, with no signs and symptoms. The patient is asymptomatic and the transplanted tooth is still functional with no signs of marginal periodontal pathosis. Radiographies showed bone regeneration in the site of previous extensive periapical lesion, normal periodontal ligament with no signs of root resorption. PMID:28179939

  20. Remodeling of Autogenous Bone Grafts after Osteotome Sinus Floor Elevation Assessed by Limited Cone Beam Computed Tomography

    PubMed Central

    Nishida, Tetsuya; Takenouchi, Yuka; Mori, Kyoko; Ariji, Miyuki; Nishida, Kaori; Ito, Koichi

    2013-01-01

    This study assessed the radiographic appearance of bone graft domes longitudinally after osteotome sinus floor elevation using cone beam computed tomography (CBCT). This study presents the radiological findings of a 6-month follow-up CBCT study in maxillary osteotome sinus floor elevation. We examined 52 patients with a crestal bone height of less than 8 mm in the posterior maxilla who required sinus augmentation. Implants (n = 91) were subsequently placed in regenerated bone following osteotome sinus floor elevation; autogenous bone was used as the augmentation material. In all cases, the grafted augmentation material tended to be absorbed, but at least 1 mm of grafted augmentation material was recognized around the implant fixtures on CBCT at the second implant operation. The border between the grafted augmentation material and the existing bone was indistinct. The grafted area apical to the implants undergoes shrinkage and remodeling. It was suggested that sufficient grafted autogenous bone changes into bone to support an implant. PMID:23956747

  1. Estimating crack growth in temperature damaged concrete

    NASA Astrophysics Data System (ADS)

    Recalde, Juan Jose

    2009-12-01

    Evaluation of the structural condition of deteriorated concrete infrastructure and evaluation of new sustainable cementitious materials require an understanding of how the material will respond to applied loads and environmental exposures. A fundamental understanding of how microstructural changes in these materials relate to changes in mechanical properties and changes in fluid penetrability is needed. The ability to provide rapid, inexpensive assessment of material characteristics and relevant engineering properties is valuable for decision making and asset management purposes. In this investigation, the effects of changes in dynamic elastic properties with water content and fluid penetrability properties before and after a 300°C exposure were investigated based on estimates of the crack density parameter from dry and saturated cracked media. The experimental and analytical techniques described in this dissertation allow calculation of a value for the crack density parameter using nondestructive determination of wet and dry dynamic shear modulus of relatively thin disks. The techniques were used to compare a conventional concrete mixture to several mixtures with enhanced sustainability characteristics. The three enhanced sustainable materials investigated were a very high fly ash mixture, a magnesium phosphate cement based mortar, and a magnesium phosphate cement based concrete, and were compared to a conventional concrete mixture. The analysis provided both quantitative assessment of changes with high temperature damage and autogenous healing, and estimates of changes in mean crack trace lengths. The results showed that water interaction, deterioration due to damage, and autogenous healing recovery were different for the magnesium phosphate cement based mixtures than the portland cement based concrete mixtures. A strong correlation was found between log-transformed Air Permeability Index, dynamic shear modulus, and crack density parameter. The findings imply

  2. Heat shrinkage of electron beam modified EVA

    NASA Astrophysics Data System (ADS)

    Datta, Sujit K.; Chaki, T. K.; Tikku, V. K.; Pradhan, N. K.; Bhowmick, A. K.

    1997-10-01

    Heat shrinkage of electron beam modified ethylene vinyl acetate copolymer (EVA) has been investigated over a range of times, temperatures, stretching, irradiation doses and trimethylolpropane trimethacrylate (TMPTMA) levels. The irradiated (radiation dose 50 kGy and TMPTMA level 1%) and stretched (100% elongation) sample shrinks to a maximum level when kept at 453K temperature for 60 s. The heat shrinkage of samples irradiated with radiation doses of 20, 50, 100 and 150 kGy increases sharply with increasing stretching in the initial stage. Amnesia rating decreases with increasing radiation dose and TMPTMA level as well as gel content. The high radiation dose and TMPTMA level lower the heat shrinkage due to the chain scission. The effect of temperature at which extension is carried out on heat shrinkage is marginal. The irradiated (radiation dose 50 kGy and TMPTMA level 1%) EVA tubes of different dimensions expanded in a laboratory grade tube expander show similar behaviour at 453K and 60 s. The X-ray and DSC studies reveal that the crystallinity increases on stretching due to orientation of chains and it decreases to a considerable extent on heat shrinking. The theoretical and experimental values of heat shrinkage for tubes and rectangular strips are in good accord, when the radiation dose is 50 kGy and TMPTMA level 1%.

  3. Phobic postural vertigo treated with autogenic training: a case report

    PubMed Central

    Goto, Fumiyuki; Nakai, Kimiko; Kunihiro, Takanobu; Ogawa, Kaoru

    2008-01-01

    Background Patients suffering from dizziness due to vertigo are commonly encountered in the department of otolaryngology. If various clinical examinations do not reveal any objective findings, then the patients are referred to the department of internal medicine or psychiatry. In many cases, the diagnosis is psychological dizziness. Phobic postural vertigo, which was first reported by Brandt T et al in 1994, is supposed to be a type of psychological dizziness. The diagnosis is based on 6 characteristics proposed by Brandt et al. Patients are usually treated with conventional medical therapy, but some cases may be refractory to such a therapy. Psychotherapy is recommended in some cases; however, psychotherapy including autogenic training, which can be used for general relaxation, is not widely accepted. This paper describes the successful administration of autogenic training in a patient suffering from phobic postural vertigo. Case presentation We present a case of a patient who suffered from phobic postural vertigo. A 37-year-old female complained of dizziness. She had started experiencing dizziness almost 3 years She was intractable to many sort of conventional therapy. In the end, her symptom disappeared after introduction of autogenic training. Conclusion Autogenic training can be a viable and acceptable treatment option for phobic postural vertigo patients who fail to respond to other therapies. This case emphasizes the importance of autogenic training as a method to control symptom of phobic postural vertigo. PMID:18826607

  4. Technique to eliminate helium induced weld cracking in stainless steels

    SciTech Connect

    Chin-An Wang; Chin, B.A.; Grossbeck, M.L.

    1992-12-31

    Experiments have shown that Type 316 stainless steel is susceptible to heat-affected-zone (HAZ) cracking upon cooling when welded using the gas tungsten arc (GTA) process under lateral constraint. The cracking has been hypothesized to be caused by stress-assisted helium bubble growth and rupture at grain boundaries. This study utilized an experimental welding setup which enabled different compressive stresses to be applied to the plates during welding. Autogenous GTA welds were produced in Type 316 stainless steel doped with 256 appm helium. The application of a compressive stress, 55 Mpa, during welding suppressed the previously observed catastrophic cracking. Detailed examinations conducted after welding showed a dramatic change in helium bubble morphology. Grain boundary bubble growth along directions parallel to the weld was suppressed. Results suggest that stress-modified welding techniques may be used to suppress or eliminate helium-induced cracking during joining of irradiated materials.

  5. Recanalization of failed autogenous conduit utilizing laser revascularization.

    PubMed

    Chander, Rajiv K; Oza, Parind; Patel, Mayank; Balar, Nilesh

    2011-10-01

    The traditional approach for the treatment of restenosis of autogenous vein bypass has been revision of bypass with vein patch angioplasty, interposition jump graft, or thrombectomy procedures for those patients with extensive occlusive disease and limb-threatening ischemia. Endovascular intervention traditionally involves angioplasty of the graft; however, vessels with diffuse disease or extensive longitudinal lesions are generally difficult to revascularize utilizing this technique. Surgical revision of a threatened autogenous vein graft may carry a morbidity rate as high as 13.6%. We present a series of cases in which excimer laser atherectomy (LA) was used to recanalize an occluded autogenous saphenous vein bypass. Of the occluded vein bypasses failed angioplasty and were successfully atherectomized with LA measuring lengths of 35 and 30 cm, respectively. The infrainguinal has a 6-month follow-up, while the infragencular has a follow-up of 1 year, with resolution of presenting symptoms.

  6. Creeping attachment: autogenous graft vs dermal matrix allograft.

    PubMed

    Haeri, A; Parsell, D

    2000-09-01

    For many years, free autogenous grafts have been used as a method of gaining keratinized tissue around teeth with mucogingival problems. Creeping attachment using autogenous graft material has been actively studied. In addition, biocompatible, acellular connective-tissue material has recently been used as an alternative to free gingival grafts to increase the zone of keratinization. This report presents a patient with bilateral mucogingival defects in the canine and premolar areas. The patient received an autogenous graft on one side and a dermal matrix allograft on the contralateral side. Creeping attachments were measured and compared at 3 months and 12 months after surgery. After 12 months of healing, an average of 1.23 mm of creeping attachment was measured on the free gingival graft side and 0.96 mm of creeping attachment was measured with the dermal matrix allograft.

  7. STRESS CORROSION CRACKING IN TEAR DROP SPECIMENS

    SciTech Connect

    Lam, P; Philip Zapp, P; Jonathan Duffey, J; Kerry Dunn, K

    2009-05-01

    Laboratory tests were conducted to investigate the stress corrosion cracking (SCC) of 304L stainless steel used to construct the containment vessels for the storage of plutonium-bearing materials. The tear drop corrosion specimens each with an autogenous weld in the center were placed in contact with moist plutonium oxide and chloride salt mixtures. Cracking was found in two of the specimens in the heat affected zone (HAZ) at the apex area. Finite element analysis was performed to simulate the specimen fabrication for determining the internal stress which caused SCC to occur. It was found that the tensile stress at the crack initiation site was about 30% lower than the highest stress which had been shifted to the shoulders of the specimen due to the specimen fabrication process. This finding appears to indicate that the SCC initiation took place in favor of the possibly weaker weld/base metal interface at a sufficiently high level of background stress. The base material, even subject to a higher tensile stress, was not cracked. The relieving of tensile stress due to SCC initiation and growth in the HAZ and the weld might have foreclosed the potential for cracking at the specimen shoulders where higher stress was found.

  8. Salivation quantum--stomatopyrosis--autogenic training.

    PubMed

    Pokupec, Josipa-Sanja Gruden; Gruden, Vladimir; Biocina-Lukenda, Dolores

    2009-09-01

    Stomatopyrosis of 'burning mouth' syndrome, in a narrower sense of definition, is a condition characterized by sensation of burning and heating in mouth, despite its normal mucosa. This research has been directed towards treatment of stomatopyrosis, putting emphasis on the implementation of psychopharmacotherapy and psychotherapy. The research was conducted on altogether 120 respondents suffering from stomatopyrosis. The respondents were divided into two equal groups: each one comprising 60 members. All the respondents were treated by means of a standard topical therapy. All the patients were assessed clinically and by means of psychological tests measuring depression and anxiety four times: once before the treatment, after one month, after two months and after four months since the beginning of the treatment. The acquired data were afterwards statistically processed. When grading the symptoms on VAS, i.e. visual analogous scale, the subjective assessment of symptoms was marked as 7-8 cm, which shows a high degree of burning sensation. According to our study, the quantity of saliva, which was at the beginning of the research slightly decreased, normalized after the treatment. Apart from the clinical investigation of stomatopyrosis, we applied Depression and Anxiety questionnaires. On the basis of our research, we have concluded the following: the comorbidity of stomatopyrosis with the phenomena of anxiety and depression proves that, among other factors, there is a psychogenic aetiology of this disease. Autogenic training, which is a psychotherapeutic anxiolytic technique, is a therapy of choice for stomatopyrosis, which contributes not only to the elimination of oral complaints, but to the emotional rehabilitation of the patients as well, and to the reduction of dryness in the mouth.

  9. [Effects of autogenic training in elderly patients].

    PubMed

    Kircher, T; Teutsch, E; Wormstall, H; Buchkremer, G; Thimm, E

    2002-04-01

    Autogenic training (AT) is a widely available relaxation method with beneficial outcome on physiological and psychological functioning. In our study, we wanted to test the effects of an AT course in cognitively impaired, frail elderly. After a 3 month waiting period (control), AT courses (intervention) of 3 months duration were offered in 2 nursing homes. Thirty-two frail elderly took part in the study, 24 of them had a psychiatric diagnosis (mean age 82.1 +/- 7.2 years, CAMCOG 75.5 +/- 15.7, MMSE 23.3 +/- 4.3, HAMD 10.0 +/- 3.6, NOSGER 57.2 +/- 18.4, AT-SYM 32.9 +/- 17.6 points). Eight participants dropped out during the waiting period, 8 during the course. From the 16 participants, 15 (94%) were able to learn the AT according to subjective, 9 (54%) according to objective criteria. The ability to practice the AT successfully correlated with the CAMCOG (p = 0.001) and the NOSGER (p = 0.01) score. Participants with a dementia syndrome had major difficulties, whereas age, depressiveness, and number of complaints (AT-SYM) had no influence on the ability to learn the AT. There was no intervention effect, measured with the HAMD, NOSGER, AT-SYM and MMSE. In the pre-post comparison of training sessions, a significant improvement in general well being was found (p < 0.001). Mentally impaired, frail elderly participants are able to learn the AT. Cognitive impairment is disadvantageous for a successful participation.

  10. Cartilage repair with autogenic perichondrium cell and polylactic acid grafts.

    PubMed

    Dounchis, J S; Bae, W C; Chen, A C; Sah, R L; Coutts, R D; Amiel, D

    2000-08-01

    The repair of articular cartilage injuries remains a challenge, with many of the current therapeutic strategies based on the grafting or recruitment of chondrogenic tissues or cells. This 1-year study compared the repair of a 3.7-mm diameter by 3-mm deep osteochondral defect in the medial femoral condyle of 24 New Zealand White rabbits; the defect was obtained using an autogenic perichondrium cell polylactic acid composite graft with a contralateral control in which the osteochondral defect remained empty. To elucidate the effect of host immune responses on the repair process after perichondrium cell transplantation, the results of the autogenic perichondrium cell polylactic acid graft group were compared with those obtained in the authors' previous 1-year study of allogenic perichondrium cell polylactic acid composite grafts implanted in a similar model. One year after surgery, the repair site underwent gross inspection and histologic, histomorphometric, biochemical, and biomechanical analyses. The autogenic perichondrium cell polylactic acid graft group (92%) and the control group in which the osteochondral defect remained empty (88%) resulted in a high percentage of grossly acceptable repairs. The autogenic grafts appeared to augment the intrinsic healing capacity of the animals (as compared with the animals in the No Implant Group). The autogenic perichondrium cell polylactic and grafts improved the histologic appearance and percentage of Type II collagen of the cartilaginous repair tissue. Compared with allogenic grafts, the autogenic grafts had better reconstitution of the subchondral bone. However, the results of this experimental model suggest a suboptimal concentration of glycosaminoglycans in the neocartilage matrix, a depressed surface of the repair tissue, a histologic appearance that was not equivalent to that of normal articular cartilage, and reduced biomechanical properties for the repair tissue. The future application of growth factors to this

  11. Creep and shrinkage effects on integral abutment bridges

    NASA Astrophysics Data System (ADS)

    Munuswamy, Sivakumar

    Integral abutment bridges provide bridge engineers an economical design alternative to traditional bridges with expansion joints owing to the benefits, arising from elimination of expensive joints installation and reduced maintenance cost. The superstructure for integral abutment bridges is cast integrally with abutments. Time-dependent effects of creep, shrinkage of concrete, relaxation of prestressing steel, temperature gradient, restraints provided by abutment foundation and backfill and statical indeterminacy of the structure introduce time-dependent variations in the redundant forces. An analytical model and numerical procedure to predict instantaneous linear behavior and non-linear time dependent long-term behavior of continuous composite superstructure are developed in which the redundant forces in the integral abutment bridges are derived considering the time-dependent effects. The redistributions of moments due to time-dependent effects have been considered in the analysis. The analysis includes nonlinearity due to cracking of the concrete, as well as the time-dependent deformations. American Concrete Institute (ACI) and American Association of State Highway and Transportation Officials (AASHTO) models for creep and shrinkage are considered in modeling the time dependent material behavior. The variations in the material property of the cross-section corresponding to the constituent materials are incorporated and age-adjusted effective modulus method with relaxation procedure is followed to include the creep behavior of concrete. The partial restraint provided by the abutment-pile-soil system is modeled using discrete spring stiffness as translational and rotational degrees of freedom. Numerical simulation of the behavior is carried out on continuous composite integral abutment bridges and the deformations and stresses due to time-dependent effects due to typical sustained loads are computed. The results from the analytical model are compared with the

  12. Compensating for Shrinkage in Machined Ceramics

    NASA Technical Reports Server (NTRS)

    Aguilar, L.; Fitchett, B. T.

    1986-01-01

    Technique insures machined ceramics shrink to correct dimensions after baked in kiln. New method automatically compensates during machining for shrinkage later, when part baked. Applicable to numerically controlled machines that include provision to adjust for variations in cuttingtool size, but do not provide for automatic verification of dimensions of machined parts.

  13. A Bayesian Shrinkage Approach for AMMI Models

    PubMed Central

    de Oliveira, Luciano Antonio; Nuvunga, Joel Jorge; Pamplona, Andrezza Kéllen Alves

    2015-01-01

    Linear-bilinear models, especially the additive main effects and multiplicative interaction (AMMI) model, are widely applicable to genotype-by-environment interaction (GEI) studies in plant breeding programs. These models allow a parsimonious modeling of GE interactions, retaining a small number of principal components in the analysis. However, one aspect of the AMMI model that is still debated is the selection criteria for determining the number of multiplicative terms required to describe the GE interaction pattern. Shrinkage estimators have been proposed as selection criteria for the GE interaction components. In this study, a Bayesian approach was combined with the AMMI model with shrinkage estimators for the principal components. A total of 55 maize genotypes were evaluated in nine different environments using a complete blocks design with three replicates. The results show that the traditional Bayesian AMMI model produces low shrinkage of singular values but avoids the usual pitfalls in determining the credible intervals in the biplot. On the other hand, Bayesian shrinkage AMMI models have difficulty with the credible interval for model parameters, but produce stronger shrinkage of the principal components, converging to GE matrices that have more shrinkage than those obtained using mixed models. This characteristic allowed more parsimonious models to be chosen, and resulted in models being selected that were similar to those obtained by the Cornelius F-test (α = 0.05) in traditional AMMI models and cross validation based on leave-one-out. This characteristic allowed more parsimonious models to be chosen and more GEI pattern retained on the first two components. The resulting model chosen by posterior distribution of singular value was also similar to those produced by the cross-validation approach in traditional AMMI models. Our method enables the estimation of credible interval for AMMI biplot plus the choice of AMMI model based on direct posterior

  14. A Bayesian Shrinkage Approach for AMMI Models.

    PubMed

    da Silva, Carlos Pereira; de Oliveira, Luciano Antonio; Nuvunga, Joel Jorge; Pamplona, Andrezza Kéllen Alves; Balestre, Marcio

    2015-01-01

    Linear-bilinear models, especially the additive main effects and multiplicative interaction (AMMI) model, are widely applicable to genotype-by-environment interaction (GEI) studies in plant breeding programs. These models allow a parsimonious modeling of GE interactions, retaining a small number of principal components in the analysis. However, one aspect of the AMMI model that is still debated is the selection criteria for determining the number of multiplicative terms required to describe the GE interaction pattern. Shrinkage estimators have been proposed as selection criteria for the GE interaction components. In this study, a Bayesian approach was combined with the AMMI model with shrinkage estimators for the principal components. A total of 55 maize genotypes were evaluated in nine different environments using a complete blocks design with three replicates. The results show that the traditional Bayesian AMMI model produces low shrinkage of singular values but avoids the usual pitfalls in determining the credible intervals in the biplot. On the other hand, Bayesian shrinkage AMMI models have difficulty with the credible interval for model parameters, but produce stronger shrinkage of the principal components, converging to GE matrices that have more shrinkage than those obtained using mixed models. This characteristic allowed more parsimonious models to be chosen, and resulted in models being selected that were similar to those obtained by the Cornelius F-test (α = 0.05) in traditional AMMI models and cross validation based on leave-one-out. This characteristic allowed more parsimonious models to be chosen and more GEI pattern retained on the first two components. The resulting model chosen by posterior distribution of singular value was also similar to those produced by the cross-validation approach in traditional AMMI models. Our method enables the estimation of credible interval for AMMI biplot plus the choice of AMMI model based on direct posterior

  15. Shrinkage of dental composite in simulated cavity measured with digital image correlation.

    PubMed

    Li, Jianying; Thakur, Preetanjali; Fok, Alex S L

    2014-07-21

    Polymerization shrinkage of dental resin composites can lead to restoration debonding or cracked tooth tissues in composite-restored teeth. In order to understand where and how shrinkage strain and stress develop in such restored teeth, Digital Image Correlation (DIC) was used to provide a comprehensive view of the displacement and strain distributions within model restorations that had undergone polymerization shrinkage. Specimens with model cavities were made of cylindrical glass rods with both diameter and length being 10 mm. The dimensions of the mesial-occlusal-distal (MOD) cavity prepared in each specimen measured 3 mm and 2 mm in width and depth, respectively. After filling the cavity with resin composite, the surface under observation was sprayed with first a thin layer of white paint and then fine black charcoal powder to create high-contrast speckles. Pictures of that surface were then taken before curing and 5 min after. Finally, the two pictures were correlated using DIC software to calculate the displacement and strain distributions. The resin composite shrunk vertically towards the bottom of the cavity, with the top center portion of the restoration having the largest downward displacement. At the same time, it shrunk horizontally towards its vertical midline. Shrinkage of the composite stretched the material in the vicinity of the "tooth-restoration" interface, resulting in cuspal deflections and high tensile strains around the restoration. Material close to the cavity walls or floor had direct strains mostly in the directions perpendicular to the interfaces. Summation of the two direct strain components showed a relatively uniform distribution around the restoration and its magnitude equaled approximately to the volumetric shrinkage strain of the material.

  16. Effect of Expansive Admixtures on the Shrinkage and Mechanical Properties of High-Performance Fiber-Reinforced Cement Composites

    PubMed Central

    Choi, Won-Chang; Yun, Hyun-Do

    2013-01-01

    High-performance fiber-reinforced cement composites (HPFRCCs) are characterized by strain-hardening and multiple cracking during the inelastic deformation process, but they also develop high shrinkage strain. This study investigates the effects of replacing Portland cement with calcium sulfoaluminate-based expansive admixtures (CSA EXAs) to compensate for the shrinkage and associated mechanical behavior of HPFRCCs. Two types of CSA EXA (CSA-K and CSA-J), each with a different chemical composition, are used in this study. Various replacement ratios (0%, 8%, 10%, 12%, and 14% by weight of cement) of CSA EXA are considered for the design of HPFRCC mixtures reinforced with 1.5% polyethylene (PE) fibers by volume. Mechanical properties, such as shrinkage compensation, compressive strength, flexural strength, and direct tensile strength, of the HPFRCC mixtures are examined. Also, crack width and development are investigated to determine the effects of the EXAs on the performance of the HPFRCC mixtures, and a performance index is used to quantify the performance of mixture. The results indicate that replacements of 10% CSA-K (Type 1) and 8% CSA-J (Type 2) considerably enhance the mechanical properties and reduce shrinkage of HPFRCCs. PMID:24376382

  17. Cracking catalyst

    SciTech Connect

    Otterstedt, J. E. A.; Jaras, S. G.; Pudas, R.; Upson, L. L.

    1985-05-07

    A cracking catalyst having good resistance to metal poisoning has at least two particle fractions of different particle sizes, the cracking catalyzing zeolite material being concentrated to the coarser particle size fractions, and the finer particle size fractions being formed from material having relatively lower or no or insignificant cracking catalyzing activity. The particles of the finer particle size fractions have a matrix of kaolin and amorphous alumina--silica and may contain for example, an SO /SUB x/ eliminating additive such as Al/sub 2/O/sub 3/, CaO and/or MgO. The coarser particle size fractions having cracking catalyzing effect have a mean particle size of from 80 to 125 ..mu..m and the finer particle size fractions a mean particle size of from 30 to 75 ..mu..m. The coarser particle size fractions have a zeolite content of at least 20 weight % and may have a zeolite content of up to 100 weight %, the remainder consisting essentially of material which has relatively lower or no or insignificant cracking-catalyzing activity and which consists of kaolin and amorphous alumina-silica. The catalyst mass as a whole may have a zeolite content of up to 50 weight %.

  18. Autogenic training: a narrative and quantitative review of clinical outcome.

    PubMed

    Linden, W

    1994-09-01

    This review of controlled outcome research on Autogenic Training complements the literature by pooling narrative and quantitative approaches, by including only studies with experimental controls, by integrating the English and German literature, and by adding research findings published since the last review. Whereas previous reviews have already reported positive effects of Autogenic Training for migraine, insomnia, and test anxiety, additional supportive findings for angina pectoris, asthma, childbirth, eczema, hypertension, infertility, Raynaud's disease, and recovery from myocardial infarction are discussed here. The impact of protocol variations on outcome is described, and the specificity of Autogenic Training relative to other stress management techniques is highlighted. Quantitative findings suggested that Autogenic Training was associated with medium-sized pre- to posttreatment effects ranging from d = .43 for biological indices of change to d = .58 for psychological and behavioral indices thus matching effect sizes for other biobehavioral treatment techniques like biofeedback and muscular relaxation. Length of treatment did not affect clinical outcome. The discussion emphasizes how narrative and quantitative strategies complement one another.

  19. Treatment of Childhood Migraine Using Autogenic Feedback Training.

    ERIC Educational Resources Information Center

    Labbe, Elise L.

    1984-01-01

    Compared autogenic feedback training with a waiting-list control group as a treatment for children (N=28) with migraine headaches. Children in the treatment condition were significantly improved at the end of treatment and at one-month and six-month follow-up. No improvement was found for the children in the control condition. (BH)

  20. Mandibular Tori: A source of autogenous bone graft

    PubMed Central

    Santhanakrishnan, Muthukumar; Rangarao, Suresh

    2014-01-01

    Restoration of lost alveolar bone support remains as one of the main objectives of periodontal surgery. Amongst the various types of bone grafts available for grafting procedures, autogenous bone grafts are considered to be the gold standard in alveolar defect reconstruction. Although there are various sources for autogenous grafts including the mandibular symphysis and ramus, they are almost invariably not contiguous with the area to be augmented. An alternative mandibular donor site that is continuous with the recipient area and would eliminate the need for an extra surgical site is the tori/exostoses. Bone grafting was planned for this patient as there were angular bone loss present between 35-36 and 36-37. As the volume of bone required was less and bilateral tori were present on the lingual side above the mylohyoid line, the tori was removed and used as a source of autogenous bone graft, which were unnecessary bony extensions present on the mandible and continuous with the recipient area. Post-operative radiographs taken at 6 and 12 month intervals showed good bone fill and also areas of previous pockets, which did not probe after treatment indicates the success of the treatment. The use of mandibular tori as a source of autogenous bone graft should be considered whenever a patient requires bone grafting procedure to be done and presents with a tori. PMID:25624635

  1. Autogenous Metallic Pipe Leak Repair in Potable Water Systems.

    PubMed

    Tang, Min; Triantafyllidou, Simoni; Edwards, Marc A

    2015-07-21

    Copper and iron pipes have a remarkable capability for autogenous repair (self-repair) of leaks in potable water systems. Field studies revealed exemplars that metallic pipe leaks caused by nails, rocks, and erosion corrosion autogenously repaired, as confirmed in the laboratory experiments. This work demonstrated that 100% (N = 26) of 150 μm leaks contacting representative bulk potable water in copper pipes sealed autogenously via formation of corrosion precipitates at 20-40 psi, pH 3.0-11.0, and with upward and downward leak orientations. Similar leaks in carbon steel pipes at 20 psi self-repaired at pH 5.5 and 8.5, but two leaks did not self-repair permanently at pH 11.0 suggesting that water chemistry may control the durability of materials that seal the leaks and therefore the permanence of repair. Larger 400 μm holes in copper pipes had much lower (0-33%) success of self-repair at pH 3.0-11.0, whereas all 400 μm holes in carbon steel pipes at 20 psi self-repaired at pH 4.0-11.0. Pressure tests indicated that some of the repairs created at 20-40 psi ambient pressure could withstand more than 100 psi without failure. Autogenous repair has implications for understanding patterns of pipe failures, extending the lifetime of decaying infrastructure, and developing new plumbing materials.

  2. Discrete multiscale wavelet shrinkage and integrodifferential equations

    NASA Astrophysics Data System (ADS)

    Didas, S.; Steidl, G.; Weickert, J.

    2008-04-01

    We investigate the relation between discrete wavelet shrinkage and integrodifferential equations in the context of simplification and denoising of one-dimensional signals. In the continuous setting, strong connections between these two approaches were discovered in 6 (see references). The key observation is that the wavelet transform can be understood as derivative operator after the convolution with a smoothing kernel. In this paper, we extend these ideas to the practically relevant discrete setting with both orthogonal and biorthogonal wavelets. In the discrete case, the behaviour of the smoothing kernels for different scales requires additional investigation. The results of discrete multiscale wavelet shrinkage and related discrete versions of integrodifferential equations are compared with respect to their denoising quality by numerical experiments.

  3. Matrix cracking in brittle-matrix composites with tailored interfaces

    SciTech Connect

    Danchaivijit, S.; Chao, L.Y.; Shetty, D.K.

    1995-10-01

    Matrix cracking from controlled through cracks with bridging filaments was studied in a model unidirectional composite of SiC filaments in an epoxy-bonded alumina matrix. An unbonded, frictional interface was produced by moderating the curing shrinkage of the epoxy with the alumina filler and coating the filaments with a releasing agent. Uniaxial tension test specimens (2.5 x 25 x 125 mm) with filament-bridged through cracks were fabricated by a novel two-step casting technique involving casting, precracking and joining of cracked and uncracked sections. Distinct matrix-cracking stresses, corresponding to the extension of the filament-bridged cracks, were measured in uniaxial tension tests using a high-sensitivity extensometer. The crack-length dependence of the matrix-cracking stress was found to be in good agreement with the prediction of a fracture-mechanics analysis that employed a new crack-closure force-crack-opening displacement relation in the calculation of the stress intensity for fiber-bridged cracks. The prediction was based on independent experimental measurements of the matrix fracture toughness (K{sub cm}), the interfacial sliding friction stress ({tau}) and the residual stress in the matrix ({sigma}{sub m}{sup I}). The matrix-cracking stress for crack lengths (2a) greater than 3 mm was independent of the crack length and agreed with the prediction of the steady-state theory of Budiansky, Hutchinson and Evans. Tests on specimens without the deliberately introduced cracks indicated a matrix-cracking stress significantly higher than the steady-state stress.

  4. Compensating For Shrinkage In A Cryogenic Seal

    NASA Technical Reports Server (NTRS)

    Hill, Arnold E.

    1993-01-01

    Proposed design for seals in liquid-hydrogen plumbing eliminates leaks caused by contraction of seals at low operating temperature. Each seal consists of rubber, polytetrafluorethylene, or lead O-ring including hollow core filled with water. At temperature of liquid hydrogen, anomalous expansion of water keeps seal gland filled and leaktight despite shrinkage of surrounding O-ring material. Design also used in systems using cryogenic fluids other than liquid hydrogen.

  5. Shrinkage deformation of cement foam concrete

    NASA Astrophysics Data System (ADS)

    Kudyakov, A. I.; Steshenko, A. B.

    2015-01-01

    The article presents the results of research of dispersion-reinforced cement foam concrete with chrysotile asbestos fibers. The goal was to study the patterns of influence of chrysotile asbestos fibers on drying shrinkage deformation of cement foam concrete of natural hardening. The chrysotile asbestos fiber contains cylindrical fiber shaped particles with a diameter of 0.55 micron to 8 microns, which are composed of nanostructures of the same form with diameters up to 55 nm and length up to 22 microns. Taking into account the wall thickness, effective reinforcement can be achieved only by microtube foam materials, the so- called carbon nanotubes, the dimensions of which are of power less that the wall pore diameter. The presence of not reinforced foam concrete pores with perforated walls causes a decrease in its strength, decreases the mechanical properties of the investigated material and increases its shrinkage. The microstructure investigation results have shown that introduction of chrysotile asbestos fibers in an amount of 2 % by weight of cement provides the finely porous foam concrete structure with more uniform size closed pores, which are uniformly distributed over the volume. This reduces the shrinkage deformation of foam concrete by 50%.

  6. Nearest shrunken centroids via alternative genewise shrinkages

    PubMed Central

    Choi, Byeong Yeob; Bair, Eric; Lee, Jae Won

    2017-01-01

    Nearest shrunken centroids (NSC) is a popular classification method for microarray data. NSC calculates centroids for each class and “shrinks” the centroids toward 0 using soft thresholding. Future observations are then assigned to the class with the minimum distance between the observation and the (shrunken) centroid. Under certain conditions the soft shrinkage used by NSC is equivalent to a LASSO penalty. However, this penalty can produce biased estimates when the true coefficients are large. In addition, NSC ignores the fact that multiple measures of the same gene are likely to be related to one another. We consider several alternative genewise shrinkage methods to address the aforementioned shortcomings of NSC. Three alternative penalties were considered: the smoothly clipped absolute deviation (SCAD), the adaptive LASSO (ADA), and the minimax concave penalty (MCP). We also showed that NSC can be performed in a genewise manner. Classification methods were derived for each alternative shrinkage method or alternative genewise penalty, and the performance of each new classification method was compared with that of conventional NSC on several simulated and real microarray data sets. Moreover, we applied the geometric mean approach for the alternative penalty functions. In general the alternative (genewise) penalties required fewer genes than NSC. The geometric mean of the class-specific prediction accuracies was improved, as well as the overall predictive accuracy in some cases. These results indicate that these alternative penalties should be considered when using NSC. PMID:28199352

  7. Desiccation cracks in siliciclastic deposits: Microbial mat-related compared to abiotic sedimentary origin

    NASA Astrophysics Data System (ADS)

    Kovalchuk, Olga; Owttrim, George W.; Konhauser, Kurt O.; Gingras, Murray K.

    2017-01-01

    Siliciclastic sediment colonized by microbial mats yield a set of distinct sedimentary fabrics that are collectively called "mat-related structures (MRS)". In the rock record, versatile cracks are observed in biostabilized strata, but the mechanisms responsible for their formation remain debated. Microbially stabilized sediments produce desiccation cracks that serve as modern analogs for fossil microbial cracks. However, since both microbial mat shrinkage and clay shrinkage may contribute to the formation of these desiccation cracks, it is difficult to isolate the influence of the microbial mat on the resulting crack formation, distribution and morphology. To address this issue, we conducted a series of desiccation experiments that determine differences between microbially influenced desiccation cracks (i.e. biotic) and those formed in identical, but sterilized (i.e. abiotic) siliciclastic sediment. Three sediment mixtures were used: (1) very fine-sized sand, (2) mixed (ungraded) silt/clay, and (3) normally graded silt/clay. In all of the experiments, the water-rich microbial mat contracted substantially while drying, producing isolated pockets of shallow, but wide cracks, the distribution of which was controlled by heterogeneities in the mat structure and thickness variations of the mat. In the clay-poor substratum, the microbial mat was the only crack-forming mechanism, while in the clay-rich substrata (experiments 2 and 3) desiccation cracks were more strongly influenced by clay shrinkage. The abiotic clay-rich sediment produced a polygonal network of deep cracks intersecting at 90-120o junctions. In the biotic clay-rich experiments, the microbial mat modified these desiccation features by withstanding crack propagation or by producing curled-up crack polygon margins. Even though a microbial mat shrinks substantially with desiccation, its cohesive nature and heterogeneous distribution prevents the formation of a regular crack network, but its shallow penetration

  8. Comparative Study of Shrinkage and Non-Shrinkage Model of Food Drying

    NASA Astrophysics Data System (ADS)

    Shahari, N.; Jamil, N.; Rasmani, KA.

    2016-08-01

    A single phase heat and mass model has always been used to represent the moisture and temperature distribution during the drying of food. Several effects of the drying process, such as physical and structural changes, have been considered in order to increase understanding of the movement of water and temperature. However, the comparison between the heat and mass equation with and without structural change (in terms of shrinkage), which can affect the accuracy of the prediction model, has been little investigated. In this paper, two mathematical models to describe the heat and mass transfer in food, with and without the assumption of structural change, were analysed. The equations were solved using the finite difference method. The converted coordinate system was introduced within the numerical computations for the shrinkage model. The result shows that the temperature with shrinkage predicts a higher temperature at a specific time compared to that of the non-shrinkage model. Furthermore, the predicted moisture content decreased faster at a specific time when the shrinkage effect was included in the model.

  9. Self-repair of cracks in brittle material systems

    NASA Astrophysics Data System (ADS)

    Dry, Carolyn M.

    2016-04-01

    One of the most effective uses for self repair is in material systems that crack because the cracks can allow the repair chemical to flow into the crack damage sites in all three dimensions. In order for the repair chemical to stay in the damage site and flow along to all the crack and repair there must be enough chemical to fill the entire crack. The repair chemical must be designed appropriately for the particular crack size and total volume of cracks. In each of the three examples of self repair in crackable brittle systems, the viscosity and chemical makeup and volume of the repair chemicals used is different for each system. Further the chemical delivery system has to be designed for each application also. Test results from self repair of three brittle systems are discussed. In "Self Repair of Concrete Bridges and Infrastructure" two chemicals were used due to different placements in bridges to repair different types of cracks- surface shrinkage and shear cracks, In "Airplane Wings and Fuselage, in Graphite" the composite has very different properties than the concrete bridges. In the graphite for airplane components the chemical also had to survive the high processing temperatures. In this composite the cracks were so definite and deep and thin that the repair chemical could flow easily and repair in all layers of the composite. In "Ceramic/Composite Demonstrating Self Repair" the self repair system not only repaired the broken ceramic but also rebounded the composite to the ceramic layer

  10. Do low-shrink composites reduce polymerization shrinkage effects?

    PubMed

    Tantbirojn, D; Pfeifer, C S; Braga, R R; Versluis, A

    2011-05-01

    Progress in polymer science has led to continuous reduction of polymerization shrinkage, exemplified by a new generation of "low-shrink composites". The common inference that shrinkage stress effects will be reduced in teeth restored with such restoratives with lower shrinkage was tested in extracted human premolars. Mesio-occluso-distal slot-shaped cavities were cut and restored with a conventional (SupremePlus) or low-shrink (RefleXions, Premise, Kalore, and LS) composite (N = 5). We digitized the coronal surfaces before and 10 min after restoration to determine cuspal deflection from the buccal and lingual volume change/area. We also determined the main properties involved (total shrinkage, post-gel shrinkage, degree of conversion, and elastic modulus), as well as microleakage, to verify adequate bonding. It was shown that, due to shrinkage stresses, buccal and lingual surfaces pulled inward after restoration (9-14 microns). Only Kalore and LS resulted in significantly lower tooth deformation (ANOVA/Student-Newman-Keuls post hoc, p = 0.05). The other two low-shrink composites, despite having the lowest and highest total shrinkage values, did not cause significant differences in cuspal deflection. Deflection seemed most related to the combination of post-gel shrinkage and elastic modulus. Therefore, even for significantly lower total shrinkage values, shrinkage stress is not necessarily reduced.

  11. Autogenic training alters cerebral activation patterns in fMRI.

    PubMed

    Schlamann, Marc; Naglatzki, Ryan; de Greiff, Armin; Forsting, Michael; Gizewski, Elke R

    2010-10-01

    Cerebral activation patterns during the first three auto-suggestive phases of autogenic training (AT) were investigated in relation to perceived experiences. Nineteen volunteers trained in AT and 19 controls were studied with fMRI during the first steps of autogenic training. FMRI revealed activation of the left postcentral areas during AT in those with experience in AT, which also correlated with the level of AT experience. Activation of prefrontal and insular cortex was significantly higher in the group with experience in AT while insular activation was correlated with number years of simple relaxation exercises. Specific activation in subjects experienced in AT may represent a training effect. Furthermore, the correlation of insular activation suggests that these subjects are different from untrained subjects in emotional processing or self-awareness.

  12. [Development of Autogenic Training Clinical Effectiveness Scale (ATCES)].

    PubMed

    Ikezuki, Makoto; Miyauchi, Yuko; Yamaguchi, Hajime; Koshikawa, Fusako

    2002-02-01

    The purpose of the present study was to develop a scale measuring clinical effectiveness of autogenic training. In Study 1, 167 undergraduates completed a survey of items concerning physical and mental states, which were thought to vary in the course of autogenic training. With item and factor analyses, 20 items were selected, and the resulting scale (ATCES) had high discrimination and clear factor structure. In Study 2, reliability and concurrent and clinical validity of the scale were examined with three groups of respondents: 85 mentally healthy, 31 control, 13 clinical persons. The scale showed a high test-retest correlation (r = .83) and alpha coefficient (alpha = .86). ATCES had a Pearson correlation coefficient of r = .56 with General Health Questionnaire (GHQ-12), and r = .73 with trait anxiety (STAI-T). And ATCES successfully discriminated the mentally healthy and clinical groups in terms of clinical effectiveness. These results demonstrated high reliability and sufficient concurrent and clinical validity of the new scale.

  13. Gorham's disease in humerus treated with autogenous vascularized fibular graft

    PubMed Central

    Kim, Jeung Woo; Kang, Hong Je; Kim, Dong Chul; Shin, Chang Hyun

    2017-01-01

    Gorham's disease is a rare disorder of the bone characterized by progressive massive osteolysis. The pathophysiology is unknown, and diagnosis is often difficult. Most cases are often recognized retrospectively. There is no standardized treatment and management for Gorham's disease. We report a case of an 18-year-old male presenting with a pathologic fracture in the humerus shaft diagnosed with Gorham's disease. Patient was treated with autogenous vascularized fibular graft with wide excision and a 10 years followup after first surgery.

  14. Entropic shrinkage of an oxide glass

    NASA Astrophysics Data System (ADS)

    Inaba, Seiji; Hosono, Hideo; Ito, Setsuro

    2015-03-01

    Entropic elasticity, a property typical of rubbers and well known in organic polymers with appropriate network structures, is not known to occur in oxide glasses. Here, we report the occurrence of entropic elasticity in phosphate-glass fibres with highly anisotropic structures, drawn by mechanical elongation from supercooled liquids. We observed a large lengthwise shrinkage of ~35% for phosphate glasses with an enhanced one-dimensional structure, as well as a distinct endotherm on reheating them up to temperatures between that of the glass transition temperature and the softening temperature. Our results strongly suggest the possibility of designing oxide glasses with a rubbery nature at high temperatures.

  15. Entropic shrinkage of an oxide glass.

    PubMed

    Inaba, Seiji; Hosono, Hideo; Ito, Setsuro

    2015-03-01

    Entropic elasticity, a property typical of rubbers and well known in organic polymers with appropriate network structures, is not known to occur in oxide glasses. Here, we report the occurrence of entropic elasticity in phosphate-glass fibres with highly anisotropic structures, drawn by mechanical elongation from supercooled liquids. We observed a large lengthwise shrinkage of ~35% for phosphate glasses with an enhanced one-dimensional structure, as well as a distinct endotherm on reheating them up to temperatures between that of the glass transition temperature and the softening temperature. Our results strongly suggest the possibility of designing oxide glasses with a rubbery nature at high temperatures.

  16. The treatment of recalcitrant post-traumatic nightmares with autogenic training and autogenic abreaction: a case study.

    PubMed

    Sadigh, M R

    1999-09-01

    Recurrent and frightening dreams are commonly experienced by patients who suffer from post-traumatic stress disorder after a motor vehicle accident. Such nocturnal episodes, if left untreated, can result in the experience of severe distress with physical, emotional, and psychophysiological concomitant. The present single-case study investigated the effects of the standard autogenic exercises and autogenic abreaction in reducing the frequency and severity of post-traumatic nightmares in a survivor of a car crash. The patient was also instructed in two additional organ-specific formulas in order to improve her sleep. The results of the study showed that the interventions were successful in effectively treating the patient's distressing nightmares. Follow-up data suggested that the treatment effects persisted after the termination of therapy. Suggestions for future investigations are discussed.

  17. Autogenic limits on allogenic controls of submarine landform evolution

    NASA Astrophysics Data System (ADS)

    Dorrell, R. M.; McCaffrey, W. D.; Burns, A. D.

    2014-12-01

    Seafloor channel avulsion events recorded in the stratigraphic architecture of submarine fans are often identified as signals of boundary change of the associated sediment supply system. However, interpretation of such signals that are persevered in the rock record is complicated by the interplay between internal (autogenic) forcing and external (allogenic) forcing on the system which may have caused the avulsion of the channel. To investigate the importance of autogenic forcing on seafloor channel evolution, novel models have been constructed which calculate the width-averaged growth of a channel levee system with progressive deposition. These models demonstrate that seafloor channel-levee systems are inherently unstable and will avulse purely subject to autogenic forcing. It is demonstrated that this instability arises as a function of geometric constraints on the cross-sectional shape of the evolving channel and its bounding levees under aggradational flow conditions. Analytical solutions to these simplified models demonstrate that change in the area of the channel is given by the comparative rate at which the bounding outer levee and channel are built up. Whilst the outer levee is built up faster than the channel, there is a relative increase in channel size - increasing the degree by which a flow is confined and thus the decreasing the likelihood of an avulsion. However, if the channel is built up faster than the outer levee the degree by which the flow is confined by the channel will decrease, and thus the likelihood of avulsion will increase. It is seen that as bounding levees become large, and thus cannot be built up as fast as the channel, the evolution of the channel is inherently limited. However, autogenic channel-levee instability likely arises over very long time periods, with the half-life of channel decay proportional to the channel-levee system size. Thus, it is expected that additional external (allogenic) forcing, such as boundary condition

  18. The Application of Autogenic Feedback Training in a Smoking Termination Program.

    ERIC Educational Resources Information Center

    Boullion, Jean K.; Chen, W. William

    1980-01-01

    Autogenic feedback training was an effective adjunct to a smoking termination program. An 81 percent reduction in smoking activity was found for the subjects who received the training. Achieving relaxation and reducing anxiety through autogenic feedback training helped subjects restore their self-confidence and deal with stress. (Author)

  19. [Efficiency of autogenous training in medical rehabilitation of patients with irritable colon syndrome with constipation dominance].

    PubMed

    Pakhomova, I V; Aĭvazian, T A; Zaĭtsev, V P; Gusakova, E V; Molina, L P

    2008-01-01

    It was established that use of autogenous training makes possible to increase efficiency of the therapy, leading to considerable more evident improvement of somatic and psychotic state, decrease of pain syndrome. Predictors of efficiency of autogenous training were marked out. Indications for use the method in medical rehabilitation of patients with irritable colon syndrome with constipation dominance were elaborated.

  20. Autogenous Regulation of Splicing of the Transcript of a Yeast Ribosomal Protein Gene

    NASA Astrophysics Data System (ADS)

    Dabeva, Mariana D.; Post-Beittenmiller, Martha A.; Warner, Jonathan R.

    1986-08-01

    The gene for a yeast ribosomal protein, RPL32, contains a single intron. The product of this gene appears to participate in feedback control of the splicing of the intron from the transcript. This autogenous regulation of splicing provides a striking analogy to the autogenous regulation of translation of ribosomal proteins in Escherichia coli.

  1. Factors affecting the shrinkage of fly ash geopolymers

    NASA Astrophysics Data System (ADS)

    Ridtirud, Charoenchai; Chindaprasirt, Prinya; Pimraksa, Kedsarin

    2011-02-01

    The shrinkage of fly ash geopolymers was studied in the present study. Fly ash was used as the source material for making the geopolymers. The effects of the concentration of NaOH, sodium silicate-to-NaOH ratio, liquid-to-ash ratio, curing temperature, and curing time on shrinkage were investigated. The geopolymers were cured at 25, 40, and 60°C, respectively. The results indicate that the shrinkage of geopolymers is strongly dependent on curing temperature and liquid-to-ash ratio. The increase in shrinkage is associated with the low strength development of geopolymers. It is also found that NaOH concentration and sodium silicate-to-NaOH ratio also affect the shrinkage of geopolymers but to a lesser extent.

  2. Total autogenous mandibular reconstruction using virtual surgical planning.

    PubMed

    Winters, Ryan; Saad, Adam; Beahm, Donald David; Wise, Matthew Whitten; St Hilaire, Hugo

    2012-09-01

    Free fibula transfer has become the workhorse in mandibular reconstruction. Total mandibular reconstruction is an uncommon procedure with added complexity. Numerous techniques have been described for such reconstruction, many requiring a temporomandibular joint prosthesis. We present a novel method where simultaneous bilateral free fibula transfer utilizing preoperative virtual surgical planning was used to produce a total autogenous reconstruction. The virtual surgical planning allows to effectively quantify the bone stock required preoperatively and facilitates intraoperative modeling of the fibula. Therefore, a more anatomically correct reconstruction is obtained resulting in improved functional and aesthetic outcomes.

  3. Cryogenic Autogenous Pressurization Testing for Robotic Refueling Mission 3

    NASA Technical Reports Server (NTRS)

    Boyle, R.; DiPirro, M.; Tuttle, J.; Francis, J.; Mustafi, S.; Li, X.; Barfknecht, P.; DeLee, C. H.; McGuire, J.

    2015-01-01

    A wick-heater system has been selected for use to pressurize the Source Dewar of the Robotic Refueling Mission Phase 3 on-orbit cryogen transfer experiment payload for the International Space Station. Experimental results of autogenous pressurization of liquid argon and liquid nitrogen using a prototype wick-heater system are presented. The wick-heater generates gas to increase the pressure in the tank while maintaining a low bulk fluid temperature. Pressurization experiments were performed in 2013 to characterize the performance of the wick heater. This paper describes the experimental setup, pressurization results, and analytical model correlations.

  4. Autogenous electrolyte, non-pyrolytically produced solid capacitor structure

    SciTech Connect

    Sharp, D.J.; Armstrong, P.S.; Paintz, J.K.G.

    1998-04-01

    This report discusses the design of a solid electrolytic capacitor having a solid electrolyte comprised of manganese dioxide dispersed in an aromatic polyamide capable of to forming polyimide linkages. This solid electrolyte being disposed between a first electrode made of valve metal covered by an anodic oxide film and a second electrode opposite the first electrode. The electrolyte autogenously produces water, oxygen, and hydroxyl groups which act as healing substances and is not itself produced pyrolytically. Reduction of the manganese dioxide and the water molecules released by formation of imide linkages result in substantially improved self-healing of anodic dielectric layer defects.

  5. A Study of the Thermal Profiles During Autogenous Arc Welding

    DTIC Science & Technology

    1989-03-01

    NAVAL POSTGRADUATE SCHOOL Monterey, California STA DTIC RAD ELECTE JUN 2 9 1989 • D THESIS A STUDY OF THE THERMAL PROFILES DURING AUTOGENOUS ARC...WELDING by Robert L. Ue March 1989 Thesis Advisor Yogendra Joshi Approved for public release; distribution is unlimited. j 7 .. 43 Unclassified security...L. LIe 13a T)pe of Report 13b Time Covered 14 Date of Report (year. month, day) 15 Page Count Master’s Thesis From To March 1989 163 16 Supplementary

  6. Autogenic-feedback training: A countermeasure for orthostatic intolerance

    NASA Technical Reports Server (NTRS)

    Cowings, Patricia S.; Toscano, William B.; Kamiya, Joe; Miller, Neal E.; Pickering, Thomas G.

    1991-01-01

    NASA has identified cardiovascular deconditioning as a serious biomedical problem associated with long-duration exposure to microgravity in space. High priority has been given to the development of countermeasures for this disorder and the resulting orthostatic intolerance experienced by crewmembers upon their return to the 1g norm of Earth. The present study was designed to examine the feasibility of training human subjects to control their own cardiovascular responses to gravitational stimulation (i.e., a tilt table). Using an operant conditioning procedure, Autogenic-Feedback Training (AFT), we would determine if subjects could learn to increase their own blood pressure voluntarily.

  7. [A case of fibromyalgia treated with medical and autogenic training].

    PubMed

    Goto, Fumiyuki; Asama, Youji; Nakai, Kimiko

    2005-12-01

    Fibromyalgia, which is relatively rare, may include symptoms of dizziness, vertigo and tinnitus. Subject was 38 years old woman reporting vertigo and whole body pain. Cochleovestibular function was normal. Pain was gradually intensified during her outpatient clinic and she was admitted. Treatments including intramusclular injection of botulinus toxin and intravenous injection of steroid were applied. Psychological counseling and autogenic training were effective in relieving her pain and vertigo. During her admission, several spells of vertigo occurred but no nystagmus was found. The abnormality in proprioception and neural disintegration may be related to vertigo. Treatment should start as early as possible together with psychological therapy.

  8. Autogenous electrolyte, non-pyrolytically produced solid capacitor structure

    DOEpatents

    Sharp, Donald J.; Armstrong, Pamela S.; Panitz, Janda Kirk G.

    1998-01-01

    A solid electrolytic capacitor having a solid electrolyte comprising manganese dioxide dispersed in an aromatic polyamide capable of further cure to form polyimide linkages, the solid electrolyte being disposed between a first electrode made of valve metal covered by an anodic oxide film and a second electrode opposite the first electrode. The electrolyte autogenously produces water, oxygen, and hydroxyl groups which act as healing substances and is not itself produced pyrolytically. Reduction of the manganese dioxide and the water molecules released by formation of imide linkages result in substantially improved self-healing of anodic dielectric layer defects.

  9. Effective Expansion: Balance between Shrinkage and Hygroscopic Expansion.

    PubMed

    Suiter, E A; Watson, L E; Tantbirojn, D; Lou, J S B; Versluis, A

    2016-05-01

    The purpose of this study was to investigate the relationship between hygroscopic expansion and polymerization shrinkage for compensation of polymerization shrinkage stresses in a restored tooth. One resin-modified glass-ionomer (RMGI) (Ketac Nano, 3M ESPE), 2 compomers (Dyract, Dentsply; Compoglass, Ivoclar), and a universal resin-based composite (Esthet•X HD, Dentsply) were tested. Volumetric change after polymerization ("total shrinkage") and during 4 wk of water storage at 37°C was measured using an optical method (n= 10). Post-gel shrinkage was measured during polymerization using a strain gauge method (n= 10). Extracted human molars with large mesio-occluso-distal slot preparations were restored with the tested restorative materials. Tooth surfaces at baseline (preparation), after restoration, and during 4 wk of 37°C water storage were scanned with an optical scanner to determine cuspal flexure (n= 8). Occlusal interface integrity was measured using dye penetration. Data were analyzed using analysis of variance and post hoc tests (significance level 0.05). All tested materials shrunk after polymerization. RMGI had the highest total shrinkage (4.65%) but lowest post-gel shrinkage (0.35%). Shrinkage values dropped significantly during storage in water but had not completely compensated polymerization shrinkage after 4 wk. All restored teeth initially exhibited inward (negative) cuspal flexure due to polymerization shrinkage. Cuspal flexure with the RMGI restoration was significantly less (-6.4 µm) than with the other materials (-12.1 to -14.1 µm). After 1 d, cuspal flexure reversed to +5.0 µm cuspal expansion with the RMGI and increased to +9.3 µm at 4 wk. After 4 wk, hygroscopic expansion compensated cuspal flexure in a compomer (Compoglass) and reduced flexure with Dyract and resin-based composite. Marginal integrity (93.7% intact restoration wall) was best for the Compoglass restorations and lowest (73.1%) for the RMGI restorations. Hygroscopic

  10. Anisotropic shrinkage characteristics of tape cast alumina

    NASA Astrophysics Data System (ADS)

    Patwardhan, Jaideep Suresh

    Dimensional control during sintering is a major issue in ceramics processing to avoid high post-sintering costs associated with machining of the fired ceramic part to desired tolerances and dimensions. Ceramic forming processes such as tape casting, injection molding, and extrusion involve shear of anisotropic particles resulting in preferential alignment of the particles in the green body. This preferential alignment causes directionality in mechanical, electrical, optical, and magnetic properties and most importantly warpage or distortion during sintering. A large effort has been devoted to synthesizing ceramic green bodies with minimal density gradients and uniform packing and modeling the sintering behavior evolution but little effort has been devoted to characterizing orientation of particles and the effect of preferential alignment on sintering shrinkage anisotropy. A systematic study was initiated to study the effect of processing variables such as shear rate, solids loading, temperature, and binder content on aqueous tape cast alumina. Three different alumina systems: A16-SG, Baikowski RC-UFX DBM and RC-LS DBM were investigated. Aqueous tapes of high solids loading alumina (56 vol. %) were tape cast at various speeds and thicknesses and assuming plane Couette flow a shear rate regime of 21--270 s-1 was investigated. Higher shear rates and high solids loading resulted in higher in-plane anisotropy whereas the anisotropy in the thickness direction was higher for low solids loading systems. The anisotropy was found to be fairly constant above a certain critical shear rate (˜100 s-1) irrespective of the temperature and the solids loading and this correlated with the viscosity-shear rate relationship of the cast slips. The higher shrinkage anisotropy in the thickness direction for the low solids loading systems (35 and 45 vol. %) was attributed to the higher amount of organics in the slip required to sustain the suitable viscosity for tape casting and

  11. Crack, crack house sex, and HIV risk.

    PubMed

    Inciardi, J A

    1995-06-01

    Limited attention has been focused on HIV risk behaviors of crack smokers and their sex partners, yet there is evidence that the crack house and the crack-using life-style may be playing significant roles in the transmission of HIV and other sexually transmitted diseases. The purposes of this research were to study the attributes and patterns of "sex for crack" exchanges, particularly those that occurred in crack houses, and to assess their potential impact on the spread of HIV. Structured interviews were conducted with 17 men and 35 women in Miami, Florida, who were regular users of crack and who had exchanged sex for crack (or for money to buy crack) during the past 30 days. In addition, participant observation was conducted in 8 Miami crack houses. Interview and observational data suggest that individuals who exchange sex for crack do so with considerable frequency, and through a variety of sexual activities. Systematic data indicated that almost a third of the men and 89% of the women had had 100 or more sex partners during the 30-day period prior to study recruitment. Not only were sexual activities anonymous, extremely frequent, varied, uninhibited (often undertaken in public areas of crack houses), and with multiple partners but, in addition, condoms were not used during the majority of contacts. Of the 37 subjects who were tested for HIV and received their test results 31% of the men and 21% of the women were HIV seropositive.

  12. Autogenic-Feedback Training Exercise (AFTE) Method and System

    NASA Technical Reports Server (NTRS)

    Cowings, Patricia S. (Inventor)

    1997-01-01

    The Autogenic-Feedback Training Exercise (AFTE) method of the present invention is a combined application of physiologic and perceptual training techniques. such as autogenic therapy and biofeedback. This combined therapy approach produces a methodology that is appreciably more effective than either of the individual techniques used separately. The AFTE method enables sufficient magnitude of control necessary to significantly reduce the behavioral and physiologic reactions to severe environmental stressors. It produces learned effects that are persistent over time and are resistant to extinction and it can be administered in a short period of time. The AFTE method may be used efficiently in several applications, among which are the following: to improve pilot and crew performance during emergency flying conditions; to train people to prevent the occurrence of nausea and vomiting associated with motion and sea sickness, or morning sickness in early pregnancy; as a training method for preventing or counteracting air-sickness symptoms in high-performance military aircraft; for use as a method for cardiovascular training, as well as for multiple other autonomic responses, which may contribute to the alleviation of Space Motion Sickness (SMS) in astronauts and cosmonauts; training people suffering from migraine or tension headaches to control peripheral blood flow and reduce forehead and/or trapezius muscle tension; training elderly people suffering from fecal incontinence to control their sphincter muscles; training cancer patients to reduce the nauseagenic effects of chemotherapy; and training patients with Chronic Intestinal Pseudo-obstruction (CIP).

  13. Autogenic heterotopic vascularized proximal interphalangeal joint transplantation in children.

    PubMed

    Chiu, David T W; Lee, Jonathan

    2011-03-01

    The proximal interphalangeal joint (PIP) joint is the most crucial joint for the functionality of a finger. For a child with complex injury of the hand every effort should be exercised to maximize function restoration. If the PIP joint is irreparably damaged, its reconstruction is indicated. The technique of autogenic heterotopic vascularized toe joint transplantation provides unique advantage of a composite transfer of skin, tendons, bone and joint alone with growth plate and its efficacy has been affirmed in children. It has been suggested that such transfers require intact flexor tendon to achieve satisfactory results, our experience however indicates quite the contrary. As evidenced by this report of a 7-year-old boy with abrasion and avulsion injury to his dominant right hand resulting in a complex defect with skin lose, extensor, flexor avulsion along with cominution of the PIP joint of his long finger. A surgical formulation of staged reconstruction scheme including an autogenic heterotopic vascularized toe joint transplantation led to complete functional restoration to his right hand.

  14. Forced expiratory technique, directed cough, and autogenic drainage.

    PubMed

    Fink, James B

    2007-09-01

    In health, secretions produced in the respiratory tract are cleared by mucociliary transport, cephalad airflow bias, and cough. In disease, increased secretion viscosity and volume, dyskinesia of the cilia, and ineffective cough combine to reduce secretion clearance, leading to increased risk of infection. In obstructive lung disease these conditions are further complicated by early collapse of airways, due to airway compression, which traps both gas and secretions. Techniques have been developed to optimize expiratory flow and promote airway clearance. Directed cough, forced expiratory technique, active cycle of breathing, and autogenic drainage are all more effective than placebo and comparable in therapeutic effects to postural drainage; they require no special equipment or care-provider assistance for routine use. Researchers have suggested that standard chest physical therapy with active cycle of breathing and forced expiratory technique is more effective than chest physical therapy alone. Evidence-based reviews have suggested that, though successful adoption of techniques such as autogenic drainage may require greater control and training, patients with long-term secretion management problems should be taught as many of these techniques as they can master for adoption in their therapeutic routines.

  15. CELL SHRINKAGE AND MONOVALENT CATION FLUXES

    PubMed Central

    Bortner, Carl D.; Cidlowski, John A.

    2007-01-01

    The loss of cell volume or cell shrinkage has been a morphological hallmark of the programmed cell death process known as apoptosis. This isotonic loss of cell volume has recently been term apoptotic volume decrease or AVD to distinguish it from inherent volume regulatory responses that occurs in cells under anisotonic conditions. Recent studies examining the intracellular signaling pathways that result in this unique cellular characteristic have determined that a fundamental movement of ions, particularly monovalent ions, underlie the AVD process and plays an important role on controlling the cell death process. An efflux of intracellular potassium was shown to be a critical aspect of the AVD process, as preventing this ion loss could protect cells from apoptosis. However, potassium plays a complex role as a loss of intracellular potassium has also been shown to be beneficial to the health of the cell. Additionally, the mechanisms that a cell employs to achieve this loss of intracellular potassium vary depending on the cell type and stimulus used to induce apoptosis, suggesting multiple ways exist to accomplish the same goal of AVD. Additionally, sodium and chloride have been shown to play a vital role during cell death in both the signaling and control of AVD in various apoptotic model systems. This review examines the relationship between this morphological change and intracellular monovalent ions during apoptosis. PMID:17321483

  16. Model Shrinkage for Discriminative Language Models

    NASA Astrophysics Data System (ADS)

    Oba, Takanobu; Hori, Takaaki; Nakamura, Atsushi; Ito, Akinori

    This paper describes a technique for overcoming the model shrinkage problem in automatic speech recognition (ASR), which allows application developers and users to control the model size with less degradation of accuracy. Recently, models for ASR systems tend to be large and this can constitute a bottleneck for developers and users without special knowledge of ASR with respect to introducing the ASR function. Specifically, discriminative language models (DLMs) are usually designed in a high-dimensional parameter space, although DLMs have gained increasing attention as an approach for improving recognition accuracy. Our proposed method can be applied to linear models including DLMs, in which the score of an input sample is given by the inner product of its features and the model parameters, but our proposed method can shrink models in an easy computation by obtaining simple statistics, which are square sums of feature values appearing in a data set. Our experimental results show that our proposed method can shrink a DLM with little degradation in accuracy and perform properly whether or not the data for obtaining the statistics are the same as the data for training the model.

  17. Shrinkage covariance matrix approach for microarray data

    NASA Astrophysics Data System (ADS)

    Karjanto, Suryaefiza; Aripin, Rasimah

    2013-04-01

    Microarray technology was developed for the purpose of monitoring the expression levels of thousands of genes. A microarray data set typically consists of tens of thousands of genes (variables) from just dozens of samples due to various constraints including the high cost of producing microarray chips. As a result, the widely used standard covariance estimator is not appropriate for this purpose. One such technique is the Hotelling's T2 statistic which is a multivariate test statistic for comparing means between two groups. It requires that the number of observations (n) exceeds the number of genes (p) in the set but in microarray studies it is common that n < p. This leads to a biased estimate of the covariance matrix. In this study, the Hotelling's T2 statistic with the shrinkage approach is proposed to estimate the covariance matrix for testing differential gene expression. The performance of this approach is then compared with other commonly used multivariate tests using a widely analysed diabetes data set as illustrations. The results across the methods are consistent, implying that this approach provides an alternative to existing techniques.

  18. Permeability Enhancement in Fine-Grained Sediments by Chemically Induced Clay Fabric Shrinkage

    SciTech Connect

    Wijesinghe, A M; Kansa, E J; Viani, B E; Blake, R G; Roberts, J J; Huber, R D

    2004-02-26

    The National Research Council [1] identified the entrapment of contaminants in fine-grained clay-bearing soils as a major impediment to the timely and cost-effective remediation of groundwater to regulatory standards. Contaminants trapped in low-permeability, low-diffusivity, high-sorptivity clays are not accessible to advective flushing by treatment fluids from permeable zones, and slowly diffuse out to recontaminate previously cleaned permeable strata. We propose to overcome this barrier to effective remediation by exploiting the ability of certain nontoxic EPA-approved chemicals (e.g., ethanol) to shrink and alter the fabric of clays, and thereby create macro-porosity and crack networks in fine-grained sediments. This would significantly reduce the distance and time scales of diffusive mass transport to advectively flushed boundaries, to yield orders of magnitude reduction in the time required to complete remediation. Given that effective solutions to this central problem of subsurface remediation do not yet exist, the cost and time benefits of successful deployment of this novel concept, both as a stand-alone technology and as an enabling pre-treatment for other remedial technologies that rely on advective delivery, is likely to be very large. This project, funded as a 1-year feasibility study by LLNL's LDRD Program, is a multi-directorate, multi-disciplinary effort that leverages expertise from the Energy & Environment Directorate, the Environmental Restoration Division, and the Manufacturing & Materials Evaluation Division of Mechanical Engineering. In this feasibility study, a ''proof-of-principle'' experiment was performed to answer the central question: ''Can clay shrinkage induced by ethanol in clay-bearing sediments overcome realistic confining stresses, crack clay, and increase its effective permeability by orders of magnitude within a time that is much smaller than the time required for diffusive mass transport of ethanol in the unaltered sediment

  19. Color Image Denoising via Discriminatively Learned Iterative Shrinkage.

    PubMed

    Sun, Jian; Sun, Jian; Xu, Zingben

    2015-11-01

    In this paper, we propose a novel model, a discriminatively learned iterative shrinkage (DLIS) model, for color image denoising. The DLIS is a generalization of wavelet shrinkage by iteratively performing shrinkage over patch groups and whole image aggregation. We discriminatively learn the shrinkage functions and basis from the training pairs of noisy/noise-free images, which can adaptively handle different noise characteristics in luminance/chrominance channels, and the unknown structured noise in real-captured color images. Furthermore, to remove the splotchy real color noises, we design a Laplacian pyramid-based denoising framework to progressively recover the clean image from the coarsest scale to the finest scale by the DLIS model learned from the real color noises. Experiments show that our proposed approach can achieve the state-of-the-art denoising results on both synthetic denoising benchmark and real-captured color images.

  20. Nuclear shrinkage in live mouse hippocampal slices.

    PubMed

    Kasischke, K; Büchner, M; Ludolph, A C; Riepe, M W

    2001-05-01

    Brain slices are used extensively for biochemical, electrophysiological and molecular investigations. However, only the time frame for electrophysiological and biochemical investigations has as yet been defined. The goal of the present study was to investigate the time course of nuclear structure in live brain slices. Hippocampal slices (300 microm) were prepared from male CD1 mice (25-30 g), stained with Hoechst 33342 (10 microM), calcein-AM (2 microM) and ethidium homodimer (4 microM), and imaged with single- and dual-photon microscopy. The volume of CA1 pyramidal cell nuclei decreased from 759+/-229 microm3 in 40-50 microm depth 25 min after preparation to 453+/-169 microm3 (P<0.001) after 60 min, 315+/-112 microm3 (P<0.001) after 120 min and 128+/-71 microm3 (P<0.001) after 8 h. Similar results were obtained on a prolonged time scale in 70-80 microm depth and with an accelerated time scale in 20-30 microm depth. Live-dead staining showed that cell damage is progressing from the surface to deeper layers of the slices in a time-dependent fashion. We conclude that nuclei of CA1 hippocampal pyramidal cells show a time- and depth-dependent shrinkage converging 8 h after slice preparation to a volume of 90-130 microm; in any depth between 20 and 80 microm. The nucleus in the superficial 80 microm of each side appears dysfunctional even at times suitable for electrophysiological and biochemical experimentation in hippocampal slices. Molecular analysis of cell regulation in brain slices may, therefore, be time-dependently distorted by progressing cell death in at least half of the tissue under investigation.

  1. Method to determine factors contributing to thermoplastic sheet shrinkage

    NASA Astrophysics Data System (ADS)

    Rensch, Greg J.; Frye, Brad A.

    A test method is presented for the determination of shrinkage behavior in vacuum-formed thermoplastic resin sheeting, as presently simulated for various resin lots, sheet-gage thicknesses, sheet orientations, and mold profiles. The thermoforming machine and vacuum-forming mold characteristics are discussed. It is established that the four variable factors exert statistically significant effects on the shrinkage response of three Declar resin lots, but that these are of no real practical significance for either engineering or manufacturing operations.

  2. Gear Crack Propagation Investigation

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Reduced weight is a major design goal in aircraft power transmissions. Some gear designs incorporate thin rims to help meet this goal. Thin rims, however, may lead to bending fatigue cracks. These cracks may propagate through a gear tooth or into the gear rim. A crack that propagates through a tooth would probably not be catastrophic, and ample warning of a failure could be possible. On the other hand, a crack that propagates through the rim would be catastrophic. Such cracks could lead to disengagement of a rotor or propeller from an engine, loss of an aircraft, and fatalities. To help create and validate tools for the gear designer, the NASA Lewis Research Center performed in-house analytical and experimental studies to investigate the effect of rim thickness on gear-tooth crack propagation. Our goal was to determine whether cracks grew through gear teeth (benign failure mode) or through gear rims (catastrophic failure mode) for various rim thicknesses. In addition, we investigated the effect of rim thickness on crack propagation life. A finite-element-based computer program simulated gear-tooth crack propagation. The analysis used principles of linear elastic fracture mechanics, and quarter-point, triangular elements were used at the crack tip to represent the stress singularity. The program had an automated crack propagation option in which cracks were grown numerically via an automated remeshing scheme. Crack-tip stress-intensity factors were estimated to determine crack-propagation direction. Also, various fatigue crack growth models were used to estimate crack-propagation life. Experiments were performed in Lewis' Spur Gear Fatigue Rig to validate predicted crack propagation results. Gears with various backup ratios were tested to validate crack-path predictions. Also, test gears were installed with special crack-propagation gages in the tooth fillet region to measure bending-fatigue crack growth. From both predictions and tests, gears with backup ratios

  3. Postoperative irradiation of fresh autogenic cancellous bone grafts

    SciTech Connect

    Schwartz, H.C.; Leake, D.L.; Kagan, A.R.; Snow, H.; Pizzoferrato, A.

    1986-01-01

    Discontinuity defects were created in the mandibles of dogs and then reconstructed immediately with fresh autogenic cancellous bone grafts and Dacron-urethane prostheses. The grafts were irradiated to a total dose of 5000 rads after waiting intervals of between 3 and 12 weeks. Nonirradiated grafts served as controls. The grafts were evaluated clinically, radiographically, and histologically. There was complete incorporation of all grafts, regardless of the interval between surgery and radiotherapy. There were no soft-tissue complications. The controls were distinguishable from the irradiated grafts only by the presence of hematopoietic bone marrow. Fibrofatty marrow was observed in the irradiated grafts. Theoretical support for this technique is found in the biology of cancellous bone grafting and the pathology of radiation injury. In view of the difficulties associated with mandibular bone grafting in preoperatively irradiated patients, a new method of reconstructing selected cancer patients who require both mandibular resection and radiotherapy is suggested.

  4. Autogenic Feedback Training Applications for Man in Space

    NASA Technical Reports Server (NTRS)

    Cowings, Patricia S.; Wade, Charles E. (Technical Monitor)

    1994-01-01

    Finding an effective treatment for the motion sickness-like symptoms that occur in space has become a high priority for NASA. This paper reviews the back-round research and procedures of an experiment designed to prevent space motion sickness in shuttle crewmembers. The preventive method used, Autogenic - Feedback Training (AFT) involves training subjects to control voluntarily several of their own physiological responses to environmental stressors. AFT has been used reliably to increase tolerance to motion sickness during around based tests in over 300 men and women under a variety of conditions that induce motion sickness, and preliminary evidence from space suggests that AFT may be an effective treatment for space motion sickness as well. Other applications of AFT described include; (1) a potential treatment for post flight orthostatic intolerance, a serious biomedical problem resulting from long duration exposure to micro-g and (2) improving pilot performance during emergency flying conditions.

  5. Autogenic reaction synthesis of photocatalysts for solar fuel generation

    SciTech Connect

    Ingram, Brian J.; Pol, Vilas G.; Cronauer, Donald C.; Ramanathan, Muruganathan

    2016-04-19

    In one preferred embodiment, a photocatalyst for conversion of carbon dioxide and water to a hydrocarbon and oxygen comprises at least one nanoparticulate metal or metal oxide material that is substantially free of a carbon coating, prepared by heating a metal-containing precursor compound in a sealed reactor under a pressure autogenically generated by dissociation of the precursor material in the sealed reactor at a temperature of at least about 600.degree. C. to form a nanoparticulate carbon-coated metal or metal oxide material, and subsequently substantially removing the carbon coating. The precursor material comprises a solid, solvent-free salt comprising a metal ion and at least one thermally decomposable carbon- and oxygen-containing counter-ion, and the metal of the salt is selected from the group consisting of Mn, Ti, Sn, V, Fe, Zn, Zr, Mo, Nb, W, Eu, La, Ce, In, and Si.

  6. Crack spectra analysis

    SciTech Connect

    Tiernan, M.

    1980-09-01

    Crack spectra derived from velocity data have been shown to exhibit systematics which reflect microstructural and textural differences between samples (Warren and Tiernan, 1980). Further research into both properties and information content of crack spectra have yielded the following: Spectral features are reproducible even at low pressures; certain observed spectral features may correspond to non-in-situ crack populations created during sample retrieval; the functional form of a crack spectra may be diagnostic of the sample's grain texture; hysteresis is observed in crack spectra between up and down pressure runs - it may be due to friction between the faces of closed crack populations.

  7. Hot-cracking mechanism in CO/sub 2/ laser beam welds of dissimilar metals involving PH martensitic stainless steels

    SciTech Connect

    Cieslak, M.J.

    1987-02-01

    Autogenous CO/sub 2/ laser beam welds were made between Alloy HP 9-4-20 and both 15-5 PH and PH 13-8 Mo stainless steel. Small scale circular-patch test specimens revealed that the combination involving the Nb-bearing alloy, 15-5 PH, was far more crack susceptible than the combination involving the Nb-free alloy, PH 13-8 Mo. Analytical electron microscopy was used to identify an NbC/austenite eutectic-like constituent as being responsible for the cracking phenomenon.

  8. Location, location & size: defects close to surfaces dominate fatigue crack initiation

    PubMed Central

    Serrano-Munoz, Itziar; Buffiere, Jean-Yves; Mokso, Rajmund; Verdu, Catherine; Nadot, Yves

    2017-01-01

    Metallic cast components inevitably contain defects such as shrinkage cavities which are inherent to the solidification process. Those defects are known to significantly alter the fatigue life of components. Yet very little is known, quantitatively, on the dangerosity of internal casting defects compared to surface ones. In this study, fatigue specimens containing controlled internal defects (shrinkage pores) are used to foster internal cracking. In situ fatigue tests monitored by X ray synchrotron tomography revealed that the internal nucleation and propagation of cracks was systematically overran by surface cracking initiated at castings defects up to ten times smaller than the internal ones. These findings indicate that the presence of internal defects in cast components can be tolerated to a larger extent than is allowed by nowadays standards PMID:28345599

  9. Gear crack propagation investigations

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Ballarini, Roberto

    1996-01-01

    Analytical and experimental studies were performed to investigate the effect of gear rim thickness on crack propagation life. The FRANC (FRacture ANalysis Code) computer program was used to simulate crack propagation. The FRANC program used principles of linear elastic fracture mechanics, finite element modeling, and a unique re-meshing scheme to determine crack tip stress distributions, estimate stress intensity factors, and model crack propagation. Various fatigue crack growth models were used to estimate crack propagation life based on the calculated stress intensity factors. Experimental tests were performed in a gear fatigue rig to validate predicted crack propagation results. Test gears were installed with special crack propagation gages in the tooth fillet region to measure bending fatigue crack growth. Good correlation between predicted and measured crack growth was achieved when the fatigue crack closure concept was introduced into the analysis. As the gear rim thickness decreased, the compressive cyclic stress in the gear tooth fillet region increased. This retarded crack growth and increased the number of crack propagation cycles to failure.

  10. TESTING AND ANALYSIS OF CAP CONCRETE STRESS AND STRAIN DUE TO SHRINKAGE, CREEP, AND EXPANSION FINAL REPORT

    SciTech Connect

    Guerrero, H.; Restivo, M.

    2011-08-01

    In-situ decommissioning of Reactors P- and R- at the Savannah River Site will require filling the reactor vessels with a special concrete based on materials such as magnesium phosphate, calcium aluminate or silica fume. Then the reactor vessels will be overlain with an 8 ft. thick layer of Ordinary Portland Cement (OPC) steel reinforced concrete, called the 'Cap Concrete'. The integrity of this protective layer must be assured to last for a sufficiently long period of time to avoid ingress of water into the reactor vessel and possible movement of radioactive contamination into the environment. During drying of this Cap Concrete however, shrinkage strains are set up in the concrete as a result of diffusion and evaporation of water from the top surface. This shrinkage varies with depth in the poured slab due to a non-uniform moisture distribution. This differential shrinkage results in restraint of the upper layers with larger shrinkage by lower layers with lesser displacements. Tensile stresses can develop at the surface from the strain gradients in the bulk slab, which can lead to surface cracking. Further, a mechanism called creep occurs during the curing period or early age produces strains under the action of restraining forces. To investigate the potential for surface cracking, an experimental and analytical program was started under TTQAP SRNL-RP-2009-01184. Slab sections made of Cap Concrete mixture were instrumented with embedded strain gages and relative humidity sensors and tested under controlled environmental conditions of 23 C and relative humidities (RH) of 40% and 80% over a period of 50 days. Calculation methods were also developed for predictions of stress development in the full-scale concrete placement over the reactor vessels. These methods were evaluated by simulating conditions for the test specimens and the calculation results compared to the experimental data. A closely similar test with strain gages was performed by Kim and Lee for a

  11. Silver-Coated Nylon Dressing Plus Active DC Microcurrent for Healing of Autogenous Skin Donor Sites

    DTIC Science & Technology

    2013-08-01

    Silver-Coated Nylon Dressing Plus Active DC Microcurrent for Healing of Autogenous Skin Donor Sites Edward W. Malin, MD, Chaya M. Galin, BSN, RN... microcurrent in comparison to silver-coated dressing with sham microcurrent on wound-closure time for autogenous skin donor sites. Methods: Four...hundred five patients were screened for treatment of their donor sites using a silver-coated nylon dressing with either sham or active microcurrent

  12. Crack initiation processes in acrylic bone cement.

    PubMed

    Sinnett-Jones, P E; Browne, M; Moffat, A J; Jeffers, J R T; Saffari, N; Buffière, J-Y; Sinclair, I

    2009-06-15

    A major constraint in improving the understanding of the micromechanics of the fatigue failure process and, hence, in optimizing bone cement performance is found in the uncertainties associated with monitoring the evolution of the internal defects that are believed to dominate in vivo failure. The present study aimed to synthesize high resolution imaging with complementary damage monitoring/detection techniques. As a result, evidence of the chronology of failure has been obtained. The earliest stages of crack initiation have been captured and it is proposed that, in the presence of a pore, crack initiation may occur away from the pore due to the combined influence of pore morphology and the presence of defects within regions of stress concentration. Furthermore, experimental evidence shows that large agglomerations of BaSO(4) are subject to microcracking during fatigue, although in the majority of cases, these are not the primary cause of failure. It is proposed that cracks may then remain contained within the agglomerations because of the clamping effect of the matrix during volumetric shrinkage upon curing.

  13. Mediated patterning of sol-gel thin layers: Shrinkage, decohesion, and lift-off

    NASA Astrophysics Data System (ADS)

    Mikalsen, Erik Arthur

    This thesis explores the unique de-cohesion and lift-off processes that occur during mediated patterning of integrated sol-gel thin films of functional materials. Mediated deposition, an additive patterning approach, was introduced by Jeon et al. (J. Mater. Res., 10[12]: 2996--9 (1995)), where microcontact printing (mu-CP) facilitated the selective transfer of a molecular 'ink' (e.g., octadecyltrichlorosilane, ODTS) to the substrate, and de-cohesion of sol-gel films occurred exclusively above the printed ink regions after heat treatment (<150°C). Patterned sol-gel films of uniform thickness were revealed after facile lift-off of cracked fragments, without the use of etchants. In this thesis, the origin and mechanics of de-cohesion and lift-off were determined through direct observations and measurements. The disparate mechanical behaviors of sol-gel films on functionalized and unmodified surfaces were determined, with emphasis on interfacial strength, in-plane biaxial stress, thin film mechanics, and crack propagation for sol-gel layers on silicon, glass and fused silica substrates. In addition, direct patterning of sol-gel layers was demonstrated for the first time on curved glassy surfaces using mu-CP and mediated patterning methods. The shrinkage and densification of sol-gel layers were determined by in-situ and ex-situ measurements, where a ˜30% decrease in thickness (t) was typical during drying of sol-gel layers (T < 300°C). Constrained shrinkage, resulting from adhesion to the supporting silicon substrate, led to a coherent (crack-free) film with biaxial stresses of ˜200 MPa (t ˜ 50 nm). For ODTS-mediated sol-gel films, however, precise in-situ wafer curvature measurements determined that film stresses never exceeded 75 MPa. Additionally, interfacial adhesive strength between the substrate and the sol-gel film were evaluated for the first time using a unique pulsed-laser stress-wave technique. An adhesive strength threshold of 15 MPa was determined for

  14. Geosynthetic clay liners shrinkage under simulated daily thermal cycles.

    PubMed

    Sarabadani, Hamid; Rayhani, Mohammad T

    2014-06-01

    Geosynthetic clay liners are used as part of composite liner systems in municipal solid waste landfills and other applications to restrict the escape of contaminants into the surrounding environment. This is attainable provided that the geosynthetic clay liner panels continuously cover the subsoil. Previous case histories, however, have shown that some geosynthetic clay liner panels are prone to significant shrinkage and separation when an overlying geomembrane is exposed to solar radiation. Experimental models were initiated to evaluate the potential shrinkage of different geosynthetic clay liner products placed over sand and clay subsoils, subjected to simulated daily thermal cycles (60°C for 8 hours and 22°C for 16 hours) modelling field conditions in which the liner is exposed to solar radiation. The variation of geosynthetic clay liner shrinkage was evaluated at specified times by a photogrammetry technique. The manufacturing techniques, the initial moisture content, and the aspect ratio (ratio of length to width) of the geosynthetic clay liner were found to considerably affect the shrinkage of geosynthetic clay liners. The particle size distribution of the subsoil and the associated suction at the geosynthetic clay liner-subsoil interface was also found to have significant effects on the shrinkage of the geosynthetic clay liner.

  15. Brain shrinkage and subdural effusion associated with ACTH administration.

    PubMed

    Satoh, J; Takeshige, H; Hara, H; Fukuyama, Y

    1982-01-01

    Sequential computed tomographic (CT) studies of 11 patients (aged five months to seven years) with intractable epilepsy treated with synthetic ACTH-Z showed brain shrinkage in all cases. Brain shrinkage started to appear on daily ACTH injections for seven days, reached the maximum within four weeks of administration (14 injections every day and then 7 injections every other day), and almost returned to the original status in seven out of nine cases which were followed up for one to three months after the therapy. The subjects aged less than two years showed more remarkable brain shrinkage than did those aged more than five years. Furthermore, two other cases were complicated by subdural effusion after ACTH therapy. It is the authors' assumption that both of these phenomena are caused by the high concentration of corticosteroid through a change of the water and electrolyte contents in the brain.

  16. Prediction of ALLOY SHRINKAGE FACTORS FOR THE INVESTMENT CASTING PROCESS

    SciTech Connect

    Sabau, Adrian S

    2006-01-01

    This study deals with the experimental measurements and numerical predictions of alloy shrinkage factors (SFs) related to the investment casting process. The dimensions of the A356 aluminum alloy casting were determined from the numerical simulation results of solidification, heat transfer, fluid dynamics, and deformation phenomena. The investment casting process was carried out using wax patterns of unfilled wax and shell molds that were made of fused silica with a zircon prime coat. The dimensions of the die tooling, wax pattern, and casting were measured, in order to determine the actual tooling allowances. Several numerical simulations were carried out, to assess the level of accuracy for the casting shrinkage. The solid fraction threshold, at which the transition from the fluid dynamics to the solid dynamics occurs, was found to be important in predicting shrinkage factors (SFs). It was found that accurate predictions were obtained for all measued dimensions when the shell mold was considered a deformable material.

  17. Shrinkage Stresses Generated during Resin-Composite Applications: A Review

    PubMed Central

    Schneider, Luis Felipe J.; Cavalcante, Larissa Maria; Silikas, Nick

    2010-01-01

    Many developments have been made in the field of resin composites for dental applications. However, the manifestation of shrinkage due to the polymerization process continues to be a major problem. The material's shrinkage, associated with dynamic development of elastic modulus, creates stresses within the material and its interface with the tooth structure. As a consequence, marginal failure and subsequent secondary caries, marginal staining, restoration displacement, tooth fracture, and/or post-operative sensitivity are clinical drawbacks of resin-composite applications. The aim of the current paper is to present an overview about the shrinkage stresses created during resin-composite applications, consequences, and advances. The paper is based on results of many researches that are available in the literature. PMID:20948573

  18. Bayesian Nonparametric Shrinkage Applied to Cepheid Star Oscillations.

    PubMed

    Berger, James; Jefferys, William; Müller, Peter

    2012-01-01

    Bayesian nonparametric regression with dependent wavelets has dual shrinkage properties: there is shrinkage through a dependent prior put on functional differences, and shrinkage through the setting of most of the wavelet coefficients to zero through Bayesian variable selection methods. The methodology can deal with unequally spaced data and is efficient because of the existence of fast moves in model space for the MCMC computation. The methodology is illustrated on the problem of modeling the oscillations of Cepheid variable stars; these are a class of pulsating variable stars with the useful property that their periods of variability are strongly correlated with their absolute luminosity. Once this relationship has been calibrated, knowledge of the period gives knowledge of the luminosity. This makes these stars useful as "standard candles" for estimating distances in the universe.

  19. Untangling climatic and autogenic signals in peat records

    NASA Astrophysics Data System (ADS)

    Morris, Paul J.; Baird, Andrew J.; Young, Dylan M.; Swindles, Graeme T.

    2016-04-01

    Raised bogs contain potentially valuable information about Holocene climate change. However, autogenic processes may disconnect peatland hydrological behaviour from climate, and overwrite and degrade climatic signals in peat records. How can genuine climate signals be separated from autogenic changes? What level of detail of climatic information should we expect to be able to recover from peat-based reconstructions? We used an updated version of the DigiBog model to simulate peatland development and response to reconstructed Holocene rainfall and temperature reconstructions. The model represents key processes that are influential in peatland development and climate signal preservation, and includes a network of feedbacks between peat accumulation, decomposition, hydraulic structure and hydrological processes. It also incorporates the effects of temperature upon evapotranspiration, plant (litter) productivity and peat decomposition. Negative feedbacks in the model cause simulated water-table depths and peat humification records to exhibit homeostatic recovery from prescribed changes in rainfall, chiefly through changes in drainage. However, the simulated bogs show less resilience to changes in temperature, which cause lasting alterations to peatland structure and function and may therefore be more readily detectable in peat records. The network of feedbacks represented in DigiBog also provide both high- and low-pass filters for climatic information, meaning that the fidelity with which climate signals are preserved in simulated peatlands is determined by both the magnitude and the rate of climate change. Large-magnitude climatic events of an intermediate frequency (i.e., multi-decadal to centennial) are best preserved in the simulated bogs. We found that simulated humification records are further degraded by a phenomenon known as secondary decomposition. Decomposition signals are consistently offset from the climatic events that generate them, and decomposition

  20. Model-based adhesive shrinkage compensation for increased bonding repeatability

    NASA Astrophysics Data System (ADS)

    Müller, Tobias; Schlette, Christian; Lakshmanan, Shunmuganathan; Haag, Sebastian; Zontar, Daniel; Sauer, Sebastian; Wenzel, Christian; Brecher, Christian; Roβmann, Jürgen

    2016-03-01

    The assembly process of optical components consists of two phases - the alignment and the bonding phase. Precision - or better process repeatability - is limited by the latter one. The limitation of the alignment precision is given by the measurement equipment and the manipulation technology applied. Today's micromanipulators in combination with beam imaging setups allow for an alignment in the range of far below 100nm. However, once precisely aligned optics need to be fixed in their position. State o f the art in optics bonding for laser systems is adhesive bonding with UV-curing adhesives. Adhesive bonding is a multi-factorial process and thus subject to statistical process deviations. As a matter of fact, UV-curing adhesives inherit shrinkage effects during their curing process, making offsets for shrinkage compensation mandatory. Enhancing the process control of the adhesive bonding process is the major goal of the activities described in this paper. To improve the precision of shrinkage compensation a dynamic shrinkage prediction is envisioned by Fraunhofer IPT. Intense research activities are being practiced to gather a deeper understanding of the parameters influencing adhesive shrinkage behavior. These effects are of different nature - obviously being the raw adhesive material itself as well as its condition, the bonding geometry, environmental parameters like surrounding temperature and of course process parameters such as curing properties. Understanding the major parameters and linking them in a model-based shrinkage-prediction environment is the basis for improved process control. Results are being deployed by Fraunhofer in prototyping, as well as volume production solutions for laser systems.

  1. Crack mitigation in concrete bridge decks through experimental analysis and computer modeling

    NASA Astrophysics Data System (ADS)

    Richardson, Douglas M.

    Bridge deck cracking can cause deterioration of bridge decks, leading to a shorter life span and poor performance. Throughout the US, cracking has been identified as a problem, with transverse cracking along the deck at regular spacings being the most prominent type. This problem is usually caused by drying shrinkage within the concrete. The material properties, restraint, and distances without expansion joints all affect the crack pattern within the deck. This study will delve into the reasons that bridge decks crack, the strains that are associated with drying shrinkage, and possible methods for abating its effects. The research is divided into two parts, the first being laboratory experimentation, which was conducted through the use of two 7 ft. x 10 ft. experimental concrete bridge bays. Each bay was instrumented with strain and temperature gages throughout the deck and girders, which collected data for six months. The first deck was poured with a control concrete mix used currently in Illinois. The second deck was poured with a type K expansive concrete, which could battle the effects of shrinkage. For both decks, the results suggest a compressive strain throughout the rebar and along the top surface of the concrete, except for the locations where cracks are found (at these locations the strain slopes upward into tension). The strain in the type K deck, though, was notably less than that in the control deck and the onset of cracking was delayed by three weeks, giving the indication of an improvement over the current mix design. The second portion of the research was focused on using a finite element model to replicate the bridge bay and study the results. Equivalent temperature loading was used to apply the shrinkage loads recorded during the experimental portion of the research. The model was then expanded to encompass a full-scale bridge and in order to provide some insight into shrinkage strain in the real world. The end goal is to help alleviate cracking

  2. Chronobiometric assessment of autogenic training effects upon blood pressure and heart rate.

    PubMed

    Watanabe, Y; Halberg, F; Cornélissen, G; Saito, Y; Fukuda, K; Otsuka, K; Kikuchi, T

    1996-12-01

    Autogenic training, a method of self-hypnosis, lowers the extent of within-day variation of systolic blood pressure assessed by the circadian double amplitude. The blood pressure and heart rate of ten patients, conventionally diagnosed as having hypertension or white-coat hypertension, were automatically monitored at 30-min intervals for 7 days before autogenic training and again for 7 days, at 1 or 2 months after the start of autogenic training (practiced three times daily). The circadian double amplitude of systolic blood pressure of the patients investigated was 3 to 17 mm Hg lower on autogenic training. In 5 patients, reductions by 7 to 17 mm Hg were statistically significant. These results are regarded as provisional statistics, the utility of which depends on replication. By contrast, the over-all group reduction of the circadian double amplitude of systolic blood pressure by 8 mm Hg on the average can be taken at face value. Autogenic training also lowered the circadian double amplitude of diastolic blood pressure, but the effect was small as was the effect of autogenic training upon the MESOR (a rhythm adjusted mean) and acrophase (a measure of the timing of over-all high values recurring each day). The effect of autogenic training upon the circadian double amplitude of systolic blood pressure suggests its trial as first-line treatment of patients with an excessive circadian blood pressure amplitude, a condition which, even in the absence of an elevated 24-hr, average of blood pressure, is associated with a large increase in the risk of developing ischemic stroke or nephropathy.

  3. Minimum risk wavelet shrinkage operator for Poisson image denoising.

    PubMed

    Cheng, Wu; Hirakawa, Keigo

    2015-05-01

    The pixel values of images taken by an image sensor are said to be corrupted by Poisson noise. To date, multiscale Poisson image denoising techniques have processed Haar frame and wavelet coefficients--the modeling of coefficients is enabled by the Skellam distribution analysis. We extend these results by solving for shrinkage operators for Skellam that minimizes the risk functional in the multiscale Poisson image denoising setting. The minimum risk shrinkage operator of this kind effectively produces denoised wavelet coefficients with minimum attainable L2 error.

  4. Shrinkage Prediction for the Investment Casting of Stainless Steels

    SciTech Connect

    Sabau, Adrian S

    2007-01-01

    In this study, the alloy shrinkage factors were obtained for the investment casting of 17-4PH stainless steel parts. For the investment casting process, unfilled wax and fused silica with a zircon prime coat were used for patterns and shell molds, respectively. Dimensions of the die tooling, wax pattern, and casting were measured using a Coordinate Measurement Machine in order to obtain the actual tooling allowances. The alloy dimensions were obtained from numerical simulation results of solidification, heat transfer, and deformation phenomena. The numerical simulation results for the shrinkage factors were compared with experimental results.

  5. Sinusfloor elevation and grafting with autogenous iliac crest bone.

    PubMed

    van den Bergh, J P; ten Bruggenkate, C M; Krekeler, G; Tuinzing, D B

    1998-12-01

    Insufficient bone height in the posterior area of the maxilla, due to expansion of the maxillary sinus and atrophic reduction of the alveolar process of the maxilla, represents a contra-indication for insertion of dental implants. This anatomic problem can, in many cases, be solved by augmentation of the floor of the maxillary sinus. This surgical technique was introduced by Tatum. The so-called top hinge door method creates a new floor of the maxillary sinus at a more cranial level. Underneath this new floor the existing space is filled with a bone graft. Implantation in the alveolar process with increased bone height allows insertion of dental implants. This sinus grafting technique was used in the present study. In total, 62 sinusfloor elevations were performed with cancellous iliac bone grafts in 42 patients. In those 62 augmented sinuses, 161 ITI screw type implants were inserted. The follow-up was 1-6 years after implantation. In 2 cases infections occurred. One implant needed an extended integration time. No implants were lost. The ITI solid screw implant appears to be a suitable implant following sinusfloor elevation operations, due to its rough surface, its shape and the size of the thread. The sinusfloor elevation procedure with autogenous cancellous bone graft appears to be a valuable and reliable pre-implantological procedure, provided a proper pre-operative investigation and careful surgery are performed. This procedure allows dental implant placement with a high success rate.

  6. Dynamic correlations between heart and brain rhythm during Autogenic meditation.

    PubMed

    Kim, Dae-Keun; Lee, Kyung-Mi; Kim, Jongwha; Whang, Min-Cheol; Kang, Seung Wan

    2013-01-01

    This study is aimed to determine significant physiological parameters of brain and heart under meditative state, both in each activities and their dynamic correlations. Electrophysiological changes in response to meditation were explored in 12 healthy volunteers who completed 8 weeks of a basic training course in autogenic meditation. Heart coherence, representing the degree of ordering in oscillation of heart rhythm intervals, increased significantly during meditation. Relative EEG alpha power and alpha lagged coherence also increased. A significant slowing of parietal peak alpha frequency was observed. Parietal peak alpha power increased with increasing heart coherence during meditation, but no such relationship was observed during baseline. Average alpha lagged coherence also increased with increasing heart coherence during meditation, but weak opposite relationship was observed at baseline. Relative alpha power increased with increasing heart coherence during both meditation and baseline periods. Heart coherence can be a cardiac marker for the meditative state and also may be a general marker for the meditative state since heart coherence is strongly correlated with EEG alpha activities. It is expected that increasing heart coherence and the accompanying EEG alpha activations, heart brain synchronicity, would help recover physiological synchrony following a period of homeostatic depletion.

  7. Reorganization of the brain and heart rhythm during autogenic meditation.

    PubMed

    Kim, Dae-Keun; Rhee, Jyoo-Hi; Kang, Seung Wan

    2014-01-13

    The underlying changes in heart coherence that are associated with reported EEG changes in response to meditation have been explored. We measured EEG and heart rate variability (HRV) before and during autogenic meditation. Fourteen subjects participated in the study. Heart coherence scores were significantly increased during meditation compared to the baseline. We found near significant decrease in high beta absolute power, increase in alpha relative power and significant increases in lower (alpha) and higher (above beta) band coherence during 3~min epochs of heart coherent meditation compared to 3~min epochs of heart non-coherence at baseline. The coherence and relative power increase in alpha band and absolute power decrease in high beta band could reflect relaxation state during the heart coherent meditation. The coherence increase in the higher (above beta) band could reflect cortico-cortical local integration and thereby affect cognitive reorganization, simultaneously with relaxation. Further research is still needed for a confirmation of heart coherence as a simple window for the meditative state.

  8. Autogenic training: a meta-analysis of clinical outcome studies.

    PubMed

    Stetter, Friedhelm; Kupper, Sirko

    2002-03-01

    Autogenic training (AT) is a self-relaxation procedure by which a psychophysiological determined relaxation response is elicited. A meta-analysis was performed to evaluate the clinical effectiveness of AT. Seventy-three controlled outcome studies were found (published 1952-99). Sixty studies (35 randomized controlled trials [RCT]) qualified for inclusion in the meta-analysis. Medium-to-large effect sizes (ES) occurred for pre-post comparisons of disease-specific AT-effects, with the RCTs showing larger ES. When AT was compared to real control conditions, medium ES were found. Comparisons of AT versus other psychological treatment mostly resulted in no effects or small negative ES. This pattern of results was stable at follow-up. Unspecific AT-effects (i.e., effects on mood, cognitive performance, quality of life, and physiological variables) tended to be even larger than main effects. Separate meta-analyses for different disorders revealed a significant reduction of the heterogeneity of ES. Positive effects (medium range) of AT and of AT versus control in the meta-analysis of at least 3 studies were found for tension headache/migraine, mild-to-moderate essential hypertension, coronary heart disease, asthma bronchiale, somatoform pain disorder (unspecified type), Raynaud's disease, anxiety disorders, mild-to-moderate depression/dysthymia, and functional sleep disorders.

  9. Measuring polymerization shrinkage of photo-activated restorative materials by a water-filled dilatometer.

    PubMed

    Lai, J H; Johnson, A E

    1993-03-01

    A water-filled dilatometer specifically designed for determining the polymerization shrinkage of photo-activated composite restorative materials was used to measure the polymerization shrinkage of three visible light-activated composites. Polymerization shrinkage values ranged from 1.82% for P-50 to 2.15% and 2.19% for Herculite XRV and Prisma APH, respectively. Shrinkage data obtained in this investigation were compared with the published data, and the factors which affect shrinkage measurements were reviewed. It was concluded that maintaining a constant temperature environment (+ or - 0.02 degrees C) for the dilatometer during the shrinkage test was the most critical factor for successful application of the dilatometer.

  10. Investigation of Helicopter Longeron Cracks

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Baughman, James; Wallace, Terryl A.

    2009-01-01

    Four cracked longerons, containing a total of eight cracks, were provided for study. Cracked regions were cut from the longerons. Load was applied to open the cracks, enabling crack surface examination. Examination revealed that crack propagation was driven by fatigue loading in all eight cases. Fatigue crack initiation appears to have occurred on the top edge of the longerons near geometric changes that affect component bending stiffness. Additionally, metallurgical analysis has revealed a local depletion in alloying elements in the crack initiation regions that may be a contributing factor. Fatigue crack propagation appeared to be initially driven by opening-mode loading, but at a crack length of approximately 0.5 inches (12.7 mm), there is evidence of mixed-mode crack loading. For the longest cracks studied, shear-mode displacements destroyed crack-surface features of interest over significant portions of the crack surfaces.

  11. Application of autogenic training for anxiety disorders: a clinical study in a psychiatric setting.

    PubMed

    Sakai, M

    1997-03-01

    The effects of autogenic training for anxiety disorders were investigated in a psychiatric setting of a medical school hospital and the predictors of this treatment outcome were identified. Fifty-five patients who meet the DSM-III-R criteria for anxiety disorders were treated individually with autogenic training by the author from October 1981 to October 1995. The medical records of the patients were investigated retrospectively. The results showed that the autogenic training was successful. Twenty-eight patients (51%) were cured, fourteen (25%) much improved, eight (15%) improved and five (9%) unchanged at the end of the treatment. Forty-two patients (76%) were assessed as having had successful treatment. Pretreatment variables, such as patient's clinical characteristics, did not provide a useful guide to the outcome. Four treatment variables did have a bearing on outcome. First, practicing the second standard autogenic training exercise was a satisfactory predictor of a better outcome. Second, practicing generalization training also was a useful predictor. Third, the application of other behavioral treatment techniques was found to be positively associated with outcome. Fourth, longer treatment periods were associated with a better outcome. These findings suggested that autogenic training could be of significant benefit for the treatment of anxiety disorders.

  12. A clinical study of autogenic training-based behavioral treatment for panic disorder.

    PubMed

    Sakai, M

    1996-03-01

    The present study investigated the effect of autogenic training-based behavioral treatment for panic disorder and identified the predictors of treatment outcome. Thirty-four patients meeting DSM-III-R criteria for panic disorder received autogenic training-based behavioral treatment from October 1981 to December 1994. They were treated individually by the author. The medical records of the patients were investigated for the purpose of this study. The results showed that this autogenic training-based behavioral treatment had successful results. Fifteen patients were cured, nine much improved, five improved, and five unchanged at the end of the treatment. Improvement trends were found as for the severity of panic attack and the severity of agoraphobic avoidance. No consistent findings about predictors emerged when such pretreatment variables as demographics and severity of symptoms were used to predict the outcome. Also, three treatment variables showed useful predictive power. First, practicing the second standard autogenic training exercise satisfactorily predicted better outcomes. Second, application of in vivo exposure was found to be positively associated with the treatment outcome in patients with agoraphobic avoidance. Third, longer treatment periods were associated with better outcomes. These findings suggested that the autogenic training-based behavioral treatment could provide relief to the majority of panic disorder patients.

  13. Numerical model predictions of autogenic fluvial terraces and comparison to climate change expectations

    NASA Astrophysics Data System (ADS)

    Limaye, Ajay B. S.; Lamb, Michael P.

    2016-03-01

    Terraces eroded into sediment (alluvial) and bedrock (strath) preserve an important history of river activity. River terraces are thought to form when a river switches from a period of slow vertical incision and valley widening to fast vertical incision and terrace abandonment. Consequently, terraces are often interpreted to reflect changing external drivers including tectonics, sea level, and climate. In contrast, the intrinsic unsteadiness of lateral migration in rivers may generate terraces even under constant rates of vertical incision without external forcing. To explore this mechanism, we simulate landscape evolution by a vertically incising, meandering river and isolate the age and geometry of autogenic river terraces. Modeled autogenic terraces form for a wide range of lateral and vertical incision rates and are often paired and longitudinally extensive for intermediate ratios of vertical-to-lateral erosion rate. Autogenic terraces have a characteristic reoccurrence time that scales with the time for relief generation. There is a preservation bias against older terraces due to reworking of previously visited parts of the valley. Evolving, spatial differences in bank strength between bedrock and sediment reduce terrace formation frequency and length, favor pairing, and can explain sublinear terrace margins at valley boundaries. Age differences and geometries for modeled autogenic terraces are consistent, in cases, with natural terraces and overlap with metrics commonly attributed to terrace formation due to climate change. We suggest a new phase space of terrace properties that may allow differentiation of autogenic terraces from terraces formed by external drivers.

  14. Pebble treatment and use at Cleveland-Cliffs` autogenous milling operations

    SciTech Connect

    Greenwood, B.R.; McIvor, R.E.

    1996-12-31

    Subsidiaries of Cleveland-Cliffs Inc. operate seven iron mining operations worldwide. Of these seven operations, four North American facilities employ autogenous milling. Two of these autogenous milling circuits are in northern Michigan, the Tilden and Empire Mines, one is in northern Minnesota, Hibbing Taconite, and the fourth is the Wabush Mine in Labrador. The original autogenous milling circuit developed by Cleveland-Cliffs was at the Empire Mine. Extensive laboratory, pilot plant and full-scale testing was conducted prior to commissioning this first iron ore autogenous circuit in 1963. Since the original circuits were installed at the four mines, modifications have been made based on pilot plant and full-scale plant tests that have resulted in significant improvements in primary mill throughputs. The following is a discussion of the autogenous milling circuits at Empire, Tilden and Hibtac and the changes to the circuits related to pebble treatment and use that have been and are scheduled to be made to increase feed rates and/or improve efficiency.

  15. Flowable composite resins: do they decrease microleakage and shrinkage stress?

    PubMed

    Conte, Nicholas R; Goodchild, Jason H

    2013-06-01

    All flowable composites shrink and undergo polymerization stress; however, new technologic developments have sought to minimize this, while streamlining dental techniques and producing better results. The new category of bulk-fill flowable composites promotes the effective use of 4-mm increments while decreasing shrinkage stresses generated during polymerization.

  16. Catalytic cracking of hydrocarbons

    SciTech Connect

    Absil, R.P.L.; Bowes, E.; Green, G.J.; Marler, D.O.; Shihabi, D.S.; Socha, R.F.

    1992-02-04

    This patent describes an improvement in a catalytic cracking process in which a hydrocarbon feed is cracked in a cracking zone in the absence of added hydrogen and in the presence of a circulating inventory of solid acidic cracking a catalyst which acquires a deposit of coke that contains chemically bound nitrogen while the cracking catalyst is in the cracking zone, the coke catalyst being circulated to t regeneration zone to convert the coke catalyst to a regenerated catalyst with the formation of a flue gas comprising nitrogen oxides: the improvement comprises incorporating into the circulating catalyst inventory an amount of additive particles comprising a synthetic porous crystalline material containing copper metal or cations, to reduce the content of nitrogen oxides in the flue gas.

  17. Elevated temperature crack growth

    NASA Technical Reports Server (NTRS)

    Kim, K. S.; Vanstone, R. H.

    1992-01-01

    The purpose of this program was to extend the work performed in the base program (CR 182247) into the regime of time-dependent crack growth under isothermal and thermal mechanical fatigue (TMF) loading, where creep deformation also influences the crack growth behavior. The investigation was performed in a two-year, six-task, combined experimental and analytical program. The path-independent integrals for application to time-dependent crack growth were critically reviewed. The crack growth was simulated using a finite element method. The path-independent integrals were computed from the results of finite-element analyses. The ability of these integrals to correlate experimental crack growth data were evaluated under various loading and temperature conditions. The results indicate that some of these integrals are viable parameters for crack growth prediction at elevated temperatures.

  18. The cracked tooth.

    PubMed

    Zuckerman, G R

    1998-01-01

    Fractured molars and premolars are very common. Fractures usually result from cracks that develop and slowly extend until the tooth separates into buccal and lingual fragments. Sometimes, as these cracks expand, the patient exhibits symptoms of what is commonly referred to as "cracked tooth syndrome" (CTS). When CTS occurs, an opportunity exists to diagnose and treat these patients, to relieve their discomfort and prevent sequelae that would require more extensive treatment.

  19. Quenched catalytic cracking process

    SciTech Connect

    Krambeck, F.J.; Penick, J.E.; Schipper, P.H.

    1990-12-18

    This paper describes improvement in a fluidized catalytic cracking process wherein a fluidizable catalyst cracking catalyst and a hydrocarbon feed are charged to a reactor riser at catalytic riser cracking conditions to form catalytically cracked vapor product and spent catalyst which are discharged into a reactor vessel having a volume via a riser reactor outlet equipped with a separation means to produce a catalyst lean phase. It comprises: a majority of the cracked product, and a catalyst rich phase comprising a majority of the spend catalyst. The the catalyst rich phase is discharged into a dense bed of catalyst maintained below the riser outlet and the catalyst lean phase is discharged into the vessel for a time, and at a temperature, which cause unselective thermal cracking of the cracked product in the reactor volume before product is withdrawn from the vessel via a vessel outlet. The improvement comprises: addition, after riser cracking is completed, and after separation of cracked products from catalyst, of a quenching stream into the vessel above the dense bed of catalyst, via a quench stream addition point which allows the quench stream to contact at least a majority of the volume of the vessel above the dense bed.

  20. Elevated temperature crack growth

    NASA Technical Reports Server (NTRS)

    Kim, K. S.; Vanstone, R. H.

    1989-01-01

    Alloy 718 crack growth experiments were conducted to assess the ability of the selected path-independent (P-I) integrals to describe the elevated temperature crack growth behavior. These tests were performed on single edge notch (SEN) specimens under displacement control with multiple extensometers to monitor the specimen and crack mouth opening displacement (CMOD). The displacements in these tests were sufficiently high to induce bulk cyclic inelastic deformation of the specimen. Under these conditions, the linear elastic fracture mechanics (LEFM) parameter K does not correlate the crack growth data. The experimentally measured displacement gradients at the end of specimen gage length were used as the boundary conditions in elastic-plastic finite element method (FEM) analyses. These analyses were performed with a node release approach using CYANIDE, a GEAE FEM code, which included a gap element which is capable of efficiently simulating crack closure. Excellent correlation was obtained between the experimentally measured and predicted variation of stress and CMOD with crack length and the stress-CMOD loops for Alloy 718 tests conducted at 538 C. This confirmed the accuracy of the FEM crack growth simulation approach. The experimentally measured crack growth rate data correlated well the selected P-I integrals. These investigations have produced significant progress in developing P-I integrals as non-linear fracture mechanics parameters. The results suggest that this methodology has the potential of accurately describing elevated temperature crack growth behavior under the combined influence of thermal cycling and bulk elastic-inelastic deformation states.

  1. Cure shrinkage effects in epoxy and polycyanate matrix composites

    SciTech Connect

    Spellman, G.P.

    1995-12-22

    A relatively new advanced composite matrix, polycyanate ester, was evaluated for cure shrinkage. The chemical cure shrinkage of composites is difficult to model but a number of clever experimental techniques are available to the investigator. In this work the method of curing a prepreg layup on top of a previously cured laminate of identical ply composition is utilized. The polymeric matrices used in advanced composites have been primarily epoxies and therefore a common system of this type, Fiberite 3501-6, was used as a base case material. Three polycyanate matrix systems were selected for the study. These are: Fiberite 954-2A, YLA RS-3, and Bryte Technology BTCy-1. The first three of these systems were unidirectional prepreg with carbon fiber reinforcement. The Bryte Technology material was reinforced with E-glass fabric. The technique used to evaluate cure shrinkage results in distortion of the flatness of an otherwise symmetric laminate. The first laminate is cured in a conventional fashion. An identical layup is cured on this first laminate. During the second cure all constituents are exposed to the same thermal cycles. However, only the new portion of the laminate will experience volumetric changes associate with matrix cure. The additional strain of cure shrinkage results in an unsymmetric distribution of residual stresses and an associated warpage of the laminate. The baseline material, Fiberite 3501-6, exhibited cure shrinkage that was in accordance with expectations. Cure strains were {minus}4.5E-04. The YLA RS-3 material had cure strains somewhat lower at {minus}3.2E-04. The Fiberite 954-2A cure strain was {minus}1.5E-04 that is 70% lower than the baseline material. The glass fabric material with the Bryte BTCy-1 matrix did not result in meaningful results because the processing methods were not fully compatible with the material.

  2. Using hyperbranched oligomer functionalized glass fillers to reduce shrinkage stress

    PubMed Central

    Ye, Sheng; Azarnoush, Setareh; Smith, Ian R.; Cramer, Neil B.; Stansbury, Jeffrey W.; Bowman, Christopher N

    2012-01-01

    Objective Fillers are widely utilized to enhance the mechanical properties of polymer resins. However, polymerization stress has the potential to increase due to the higher elastic modulus achieved upon filler addition. Here, we demonstrate a hyperbranched oligomer functionalized glass filler UV curable resin composite which is able to reduce the shrinkage stress without sacrificing mechanical properties. Methods A 16-functional alkene-terminated hyperbranched oligomer is synthesized by thiol-acrylate and thiol-yne reactions and the product structure is analyzed by 1H-NMR, mass spectroscopy, and gel permeation chromatography. Surface functionalization of the glass filler is measured by thermogravimetric analysis. Reaction kinetics, mechanical properties and shrinkage stress are studied via Fourier transform infrared spectroscopy, dynamic mechanical analysis and a tensometer, respectively. Results Silica nanoparticles are functionalized with a flexible 16-functional alkene-terminated hyperbranched oligomer which is synthesized by multistage thiol-ene/yne reactions. 93% of the particle surface was covered by this oligomer and an interfacial layer ranging from 0.7 – 4.5 nm thickness is generated. A composite system with these functionalized silica nanoparticles incorporated into the thiol-yne-methacrylate resin demonstrates 30% reduction of shrinkage stress (from 0.9 MPa to 0.6 MPa) without sacrificing the modulus (3100 ± 300 MPa) or glass transition temperature (62 ± 3 °C). Moreover, the shrinkage stress of the composite system builds up at much later stages of the polymerization as compared to the control system. Significance Due to the capability of reducing shrinkage stress without sacrificing mechanical properties, this composite system will be a great candidate for dental composite applications. PMID:22717296

  3. Cloning and expression of autogenes encoding RNA polymerases of T7-like bacteriophages

    DOEpatents

    Studier, F.W.; Dubendorff, J.W.

    1998-11-03

    This invention relates to the cloning and expression of autogenes encoding RNA polymerases of T7 and T7-like bacteriophages, in which the RNA polymerase gene is transcribed from a promoter which is recognized by the encoded RNA polymerase. Cloning of T7 autogenes was achieved by reducing the activity of the RNA polymerase sufficiently to permit host cell growth. T7 RNA polymerase activity was controlled by combining two independent methods: lac-repression of the recombinant lac operator-T7 promoter in the autogene and inhibition of the polymerase by T7 lysozyme. Expression systems for producing the RNA polymerases of T7 and other T7-like bacteriophages, and expression systems for producing selected gene products are described, as well as other related materials and methods. 12 figs.

  4. Cloning and expression of autogenes encoding RNA poly,erases of T7-like bacteriophages

    DOEpatents

    Studier, F. William; Dubendorff, John W.

    1998-01-01

    This invention relates to the cloning and expression of autogenes encoding RNA polymerases of T7 and T7-like bacteriophages, in which the RNA polymerase gene is transcribed from a promoter which is recognized by the encoded RNA polymerase. Cloning of T7 autogenes was achieved by reducing the activity of the RNA polymerase sufficiently to permit host cell growth. T7 RNA polymerase activity was controlled by combining two independent methods: lac-repression of the recombinant lac operator-T7 promoter in the autogene and inhibition of the polymerase by T7 lysozyme. Expression systems for producing the RNA polymerases of T7 and other T7-like bacteriophages, and expression systems for producing selected gene products are described, as well as other related materials and methods.

  5. Cloning and expression of autogenes encoding RNA polymerases of T7-like bacteriophages

    DOEpatents

    Studier, F.W.; Dubendorff, J.W.

    1998-10-20

    This invention relates to the cloning and expression of autogenes encoding RNA polymerases of T7 and T7-like bacteriophages, in which the RNA polymerase gene is transcribed from a promoter which is recognized by the encoded RNA polymerase. Cloning of T7 autogenes was achieved by reducing the activity of the RNA polymerase sufficiently to permit host cell growth. T7 RNA polymerase activity was controlled by combining two independent methods: lac-repression of the recombinant lac operator-T7 promoter in the autogene and inhibition of the polymerase by T7 lysozyme. Expression systems for producing the RNA polymerases of T7 and other T7-like bacteriophages, and expression systems for producing selected gene products are described, as well as other related materials and methods. 12 figs.

  6. Cloning and expression of autogenes encoding RNA polymerases of T7-like bacteriophages

    DOEpatents

    Studier, F. William; Dubendorff, John W.

    1998-01-01

    This invention relates to the cloning and expression of autogenes encoding RNA polymerases of T7 and T7-like bacteriophages, in which the RNA polymerase gene is transcribed from a promoter which is recognized by the encoded RNA polymerase. Cloning of T7 autogenes was achieved by reducing the activity of the RNA polymerase sufficiently to permit host cell growth. T7 RNA polymerase activity was controlled by combining two independent methods: lac-repression of the recombinant lac operator-T7 promoter in the autogene and inhibition of the polymerase by T7 lysozyme. Expression systems for producing the RNA polymerases of T7 and other T7-like bacteriophages, and expression systems for producing selected gene products are described, as well as other related materials and methods.

  7. Untangling climate signals from autogenic changes in long-term peatland development

    NASA Astrophysics Data System (ADS)

    Morris, Paul J.; Baird, Andy J.; Young, Dylan M.; Swindles, Graeme T.

    2015-12-01

    Peatlands represent important archives of Holocene paleoclimatic information. However, autogenic processes may disconnect peatland hydrological behavior from climate and overwrite climatic signals in peat records. We use a simulation model of peatland development driven by a range of Holocene climate reconstructions to investigate climate signal preservation in peat records. Simulated water-table depths and peat decomposition profiles exhibit homeostatic recovery from prescribed changes in rainfall, whereas changes in temperature cause lasting alterations to peatland structure and function. Autogenic ecohydrological feedbacks provide both high- and low-pass filters for climatic information, particularly rainfall. Large-magnitude climatic changes of an intermediate temporal scale (i.e., multidecadal to centennial) are most readily preserved in our simulated peat records. Simulated decomposition signals are offset from the climatic changes that generate them due to a phenomenon known as secondary decomposition. Our study provides the mechanistic foundations for a framework to separate climatic and autogenic signals in peat records.

  8. Evaluation of Aquacel Ag for Autogenous Skin Donor Sites.

    PubMed

    Haith, Linwood R; Stair-Buchmann, Megan E; Ackerman, Bruce H; Herder, Diane; Reigart, Cynthia L; Stoering, Marla; Guilday, Robert E; Patton, Mary Lou; Ross, Kerry M

    2015-01-01

    An ongoing objective of burn research is to evaluate wound dressings and develop new treatments to expedite wound healing. This was a single-center, prospective, randomized, controlled study to evaluate the effectiveness of Aquacel Ag as a dressing for autogenous skin donor sites compared with Xeroform. We hypothesized that donor sites treated with Aquacel Ag would heal faster. Patients were considered for enrollment if they required skin grafting with two donor sites >100 cm at least 2 inches apart. Dressings were observed daily starting on post-op day #2 until discharge and then weekly in the outpatient burn clinic. Assessments evaluated pain, infection, and reapplication. Photographs were taken on post-op day #2, upon "90% re-epithelialization," and at post-op day #30-45. Scar assessments and blinded photographic reviews were completed to assess cosmetic healing. Twenty-nine patients completed the study. Re-epithelialization occurred faster with Xeroform (15.2 days vs. 17.6 days). Daily pain scores were higher with Xeroform (6.72 vs. 5.68) and Aquacel Ag needed to be replaced more often (1.72 times vs. 0.10 times). Three patients developed donor site infections with Aquacel Ag. Scar scores between the donor sites were not statistically significant. The blinded photo review concluded that Xeroform had a better cosmetic outcome (24 vs. 10%). Although patients complained of more pain with Xeroform, it demonstrated shorter healing times and better cosmetic outcomes. Aquacel Ag needed to be replaced more often and represented the only three donor site infections.

  9. Autogenous Regulation of Escherichia coli Polynucleotide Phosphorylase Expression Revisited▿ †

    PubMed Central

    Carzaniga, Thomas; Briani, Federica; Zangrossi, Sandro; Merlino, Giuseppe; Marchi, Paolo; Dehò, Gianni

    2009-01-01

    The Escherichia coli polynucleotide phosphorylase (PNPase; encoded by pnp), a phosphorolytic exoribonuclease, posttranscriptionally regulates its own expression at the level of mRNA stability and translation. Its primary transcript is very efficiently processed by RNase III, an endonuclease that makes a staggered double-strand cleavage about in the middle of a long stem-loop in the 5′-untranslated region. The processed pnp mRNA is then rapidly degraded in a PNPase-dependent manner. Two non-mutually exclusive models have been proposed to explain PNPase autogenous regulation. The earlier one suggested that PNPase impedes translation of the RNase III-processed pnp mRNA, thus exposing the transcript to degradative pathways. More recently, this has been replaced by the current model, which maintains that PNPase would simply degrade the promoter proximal small RNA generated by the RNase III endonucleolytic cleavage, thus destroying the double-stranded structure at the 5′ end that otherwise stabilizes the pnp mRNA. In our opinion, however, the first model was not completely ruled out. Moreover, the RNA decay pathway acting upon the pnp mRNA after disruption of the 5′ double-stranded structure remained to be determined. Here we provide additional support to the current model and show that the RNase III-processed pnp mRNA devoid of the double-stranded structure at its 5′ end is not translatable and is degraded by RNase E in a PNPase-independent manner. Thus, the role of PNPase in autoregulation is simply to remove, in concert with RNase III, the 5′ fragment of the cleaved structure that both allows translation and prevents the RNase E-mediated PNPase-independent degradation of the pnp transcript. PMID:19136586

  10. Autogenic synthesis of SnO{sub 2} materials and their structural, electrochemical, and optical properties

    SciTech Connect

    Pol, V.G.; Calderon-Moreno, J.M.; Thackeray, M.M.

    2012-12-15

    During autogenic reactions, organometallic precursors are decomposed above their critical temperature within an enclosed chamber at high temperatures and pressures. It has recently been established that such reactions can be used to synthesize carbon-coated metal oxide and metal phosphate nanoparticles. These materials are of interest as electrodes for lithium-ion batteries. In this paper, we report the autogenic fabrication of a carbon-coated SnO{sub 2} product and a carbon-free SnO{sub 2} product after removal of the carbon coating by combustion. The major objectives of the study were to monitor any beneficial effects that carbon-coated electrodes containing a lithium alloying element such as Sn might have in improving the electrical connectivity between electrode particles, which expand and contract significantly on lithiation and delithiation, and their utility in lithium cells. Specifically, we report the compositional, structural and morphological properties, and electrochemical behavior of carbon-coated SnO{sub 2} electrodes. Given the importance of the optical properties of SnO{sub 2}, we also describe the effects of the carbon coating on the optical absorbance and photoluminescence of autogenically-prepared SnO{sub 2} materials. - Graphical abstract: One-step, solvent-free autogenic reactions yield nanosized SnO{sub 2} nanoparticles, uniformly coated and interconnected by 2-4 nm carbon layers, with improved electrochemical performance. Highlights: Black-Right-Pointing-Pointer Distinctive autogenic process synthesized SnO{sub 2} nanoparticles coated with 2-4 nm carbon layers. Black-Right-Pointing-Pointer Carbon coating improved capacity retention and cycling stability of SnO{sub 2} nanoparticles. Black-Right-Pointing-Pointer Carbon coating quenched photoluminescence of SnO{sub 2} component in SnO{sub 2}-C composite. Black-Right-Pointing-Pointer Autogenic approach is extremely versatile, holds promise for designing new nanoarchitectures.

  11. Autogenous bone graft harvest using reamer irrigator aspirator (RIA) technique for tibiotalocalcaneal arthrodesis.

    PubMed

    Cuttica, Daniel J; DeVries, J George; Hyer, Christopher F

    2010-01-01

    Tibiotalocalcaneal arthrodesis is a technically demanding procedure that can be associated with a high number of complications, including nonunion. Bone grafting is commonly used in arthrodesis procedures to decrease the risk of nonunion. In this article, we describe a technique that uses a reamer-irrigator-aspirator (RIA) method for procurement of autogenous bone graft for use in tibiotalocalcaneal arthrodesis fixated with a retrograde intramedullary nail. Using the RIA technique, autogenous bone graft can be readily obtained without the need for additional incisions and dissection, thereby minimizing the need for additional sources of bone graft.

  12. Autogenous vein graft thrombosis following exposure to calcium-free solutions (calcium paradox).

    PubMed

    Nozick, J H; Farnsworth, P; Montefusco, C M; Parsonnet, V; Ruigrok, T J; Zimmerman, A N

    1981-01-01

    The morphological and functional effects of calcium-free and calcium-containing solutions on canine jugular vein intima were examined under conditions which closely resemble those techniques currently employed in peripheral vascular and aortocoronary bypass surgery. Veins that had been exposed only to calcium-containing solutions remained patent for the duration of the experimental period. Vein perfusion with a calcium-free solution, however, resulted in disruption of the jugular vein intima once calcium ions were reintroduced. Autogenous as a femoral arterial graft became thrombosed within 60 minutes. It is therefore suggested that vein grafts of autogenous origin be irrigated with calcium-containing solutions to prevent intimal damage and thrombosis.

  13. [Predictors of efficiency of autogenous melodeclamation training in patients with chronic somatic pathology].

    PubMed

    Trdatian, N A

    2009-01-01

    This controlled study involving 99 patients with chronic somatic diseases (CSD) had the objective to identify psychological predictors of the efficiency of a new method of psychotherapy, namely autogenous melodeclamation training (AMDT). Dynamics of the psychological status of the patients in the course of therapy was assessed using SMOL test, Spilberger STAI test, overall health-physical activity-mood test, and Beck depression inventory. It was shown that moderately compromised psychological adaptation and minor depressive disorders were the most reliable predictors of marked improvement of the patients' psychological status under effect of autogenous melodeclamation training included in the combined rehabilitative therapy of chronic somatic diseases.

  14. Autogenic-feedback training - A treatment for motion and space sickness

    NASA Technical Reports Server (NTRS)

    Cowings, Patricia S.

    1990-01-01

    A training method for preventing the occurrence of motion sickness in humans, called autogenic-feedback training (AFT), is described. AFT is based on a combination of biofeedback and autogenic therapy which involves training physiological self-regulation as an alternative to pharmacological management. AFT was used to reliably increase tolerance to motion-sickness-inducing tests in both men and women ranging in age from 18 to 54 years. The effectiveness of AFT is found to be significantly higher than that of protective adaptation training. Data obtained show that there is no apparent effect from AFT on measures of vestibular perception and no side effects.

  15. Pyrolytic carbon indentation crack morphology.

    PubMed

    Ely, J L; Stupka, J; Haubold, A D

    1996-06-01

    In studying fatigue and fracture behavior of brittle materials, Vickers diamond indentation cracks are often used. Many of the studies of indentation cracks use crack system models such as the radial-median crack or Palmqvist crack. These systems are also used to study small crack growth in brittle materials, and have been studied for pyrolytic carbon. However, the true morphology of these cracks in pyrolytic carbon coatings on graphite substrates have not been described. This study examined Vickers diamond and spherical ball indentation cracks in pyrolytic carbon coatings using several techniques, including serial metallographic cross sections, indentation fracture in bending, acoustic emission, and residual surface indentation scanning. The crack systems developed using these techniques were not typical of either radial median or Palmqvist systems. The morphology is unique to this material, possibly because of the coating thickness limitations. Given the difference in crack system, the application of standard indentation crack equations in studying fracture mechanics, especially for small cracks, must be questioned.

  16. Crack layer theory

    NASA Technical Reports Server (NTRS)

    Chudnovsky, A.

    1984-01-01

    A damage parameter is introduced in addition to conventional parameters of continuum mechanics and consider a crack surrounded by an array of microdefects within the continuum mechanics framework. A system consisting of the main crack and surrounding damage is called crack layer (CL). Crack layer propagation is an irreversible process. The general framework of the thermodynamics of irreversible processes are employed to identify the driving forces (causes) and to derive the constitutive equation of CL propagation, that is, the relationship between the rates of the crack growth and damage dissemination from one side and the conjugated thermodynamic forces from another. The proposed law of CL propagation is in good agreement with the experimental data on fatigue CL propagation in various materials. The theory also elaborates material toughness characterization.

  17. Modelling of elastoplastic damage in concrete due to desiccation shrinkage

    NASA Astrophysics Data System (ADS)

    Bourgeois, F.; Burlion, N.; Shao, J. F.

    2002-07-01

    We present a numerical modelling of elastoplastic damage due to drying shrinkage of concrete in the framework of mechanics of partially saturated porous media. An elastoplastic model coupled with isotropic damage is first formulated. Two plastic flow mechanisms are involved, controlled by applied stress and suction, respectively. A general concept of net effective stress is used in take into account effects of capillary pressure and material damage on stress-controlled plastic deformation. Damage evolution depends both on elastic and plastic strains. The model's parameters are determined or chosen from relevant experimental data. Comparisons between numerical simulations and experimental data are presented to show the capacity of model to reproduce mains features of concrete behaviour under mechanical loading and during drying shrinkage of concrete. An example of application concerning drying of a concrete wall is finally presented. The results obtained allow to show potential capacity of proposed model for numerical modelling of complex coupling processes in concrete structures.

  18. Reversible cerebral shrinkage in kwashiorkor: an MRI study.

    PubMed

    Gunston, G D; Burkimsher, D; Malan, H; Sive, A A

    1992-08-01

    Protein energy malnutrition is associated with cerebral atrophy which may be detrimental to intellectual development. The aim of this study was to document the anatomical abnormalities which lead to the appearance of cerebral atrophy using magnetic resonance imaging (MRI) in the acute stage of kwashiorkor and to monitor changes during nutritional rehabilitation. Twelve children aged 6 to 37 months requiring admission to hospital for the treatment of kwashiorkor were studied. The children were evaluated clinically, biochemically, and by MRI of their brains on admission and 30 and 90 days later. Brain shrinkage was present in every child on admission. White and grey matter appeared equally affected and the myelination was normal for age. At 90 days, the cerebral changes had resolved in nine and improved substantially in the remainder, by which time serum proteins and weight for age were within the normal range. The findings of this study suggest that brain shrinkage associated with kwashiorkor reverses rapidly with nutritional rehabilitation.

  19. New System of Shrinkage Measurement through Cement Mortars Drying

    PubMed Central

    Morón, Carlos; Saiz, Pablo; Ferrández, Daniel; García-Fuentevilla, Luisa

    2017-01-01

    Cement mortar is used as a conglomerate in the majority of construction work. There are multiple variants of cement according to the type of aggregate used in its fabrication. One of the major problems that occurs while working with this type of material is the excessive loss of moisture during cement hydration (setting and hardening), known as shrinkage, which provokes a great number of construction pathologies that are difficult to repair. In this way, the design of a new sensor able to measure the moisture loss of mortars at different age levels is useful to establish long-term predictions concerning mortar mass volume loss. The purpose of this research is the design and fabrication of a new capacitive sensor able to measure the moisture of mortars and to relate it with the shrinkage. PMID:28272297

  20. COMPARATIVE ANALYSIS OF THE SHRINKAGE STRESS OF COMPOSITE RESINS

    PubMed Central

    Pereira, Rosana Aparecida; de Araujo, Paulo Amarante; Castañeda-Espinosa, Juan Carlos; Mondelli, Rafael Francisco Lia

    2008-01-01

    The aim of this study was to compare the shrinkage stress of composite resins by three methods. In the first method, composites were inserted between two stainless steel plates. One of the plates was connected to a 20 kgf load cell of a universal testing machine (EMIC-DL-500). In the second method, disk-shaped cavities were prepared in 2-mm-thick Teflon molds and filled with the different composites. Gaps between the composites and molds formed after polymerization were evaluated microscopically. In the third method, the wall-to-wall shrinkage stress of the resins that were placed in bovine dentin cavities was evaluated. The gaps were measured microscopically. Data were analyzed by one-way ANOVA and Tukey's test (α=0.05). The obtained contraction forces were: Grandio = 12.18 ± 0.428N; Filtek Z 250 = 11.80 ± 0.760N; Filtek Supreme = 11.80 ± 0.707 N; and Admira = 11.89 ± 0.647 N. The gaps obtained between composites and Teflon molds were: Filtek Z 250 = 0.51 ± 0.0357%; Filtek Supreme = 0.36 ± 0.0438%; Admira = 0.25 ± 0.0346% and Grandio = 0.16 ± 0.008%. The gaps obtained in wall-to-wall contraction were: Filtek Z 250 = 11.33 ± 2.160 μm; Filtek Supreme = 10.66 ± 1.211μm; Admira = 11.16 ± 2.041 μm and Grandio = 10.50 ± 1.224 μm. There were no significant differences among the composite resins obtained with the first (shrinkage stress generated during polymerization) and third method (wall-to-wall shrinkage). The composite resins obtained with the second method (Teflon method) differed significantly regarding gap formation. PMID:19089286

  1. Visualization study on distortion of a metal frame by polymerization shrinkage and thermal contraction of resin.

    PubMed

    Kakino, Ken; Endo, Kazuhiko; Hashimoto, Masanori; Furuta, Kunihiko; Ohno, Hiroki

    2014-01-01

    Three types of metal specimens (ring-shaped, plate-shaped, and a simulated anterior arch) for distortion observations were made from Au-Ag-Pd-Cu alloy. Distortion due to polymerization shrinkage and thermal contraction of a heat-curing acrylic resin containing 4-META (4-methacryloyloxyethyl trimellitate anhydride, 4-META resin) could be visualized for the ring-shaped specimen, which showed increasing distortion of the metal frame upon adhesion of the resin to the outer metal surface. Distortion of the plateshaped specimen adhering to 4-META resin decreased with increasing thickness of the cured resin. The distortion of the metal frame simulating an anterior arch of a six-unit bridge with a facing composite resin showed that the curvature of the metal frame was larger after curing of the facing composite resin. However, it recovered most of its original curvature with an associated increase in the number of cracks between the crowns after trimming the resin to a tooth profile.

  2. Autogenic Feedback Training (Body Fortran) with Biofeedback and the Computer for Self-Improvement and Change.

    ERIC Educational Resources Information Center

    Cassel, Russell N.; Sumintardja, Elmira Nasrudin

    1983-01-01

    Describes autogenic feedback training, which provides the basis whereby an individual is able to improve on well being through use of a technique described as "body fortran," implying that you program self as one programs a computer. Necessary requisites are described including relaxation training and the management of stress. (JAC)

  3. Irreversible optical clearing of rabbit dermis for autogenic corneal stroma transplantation.

    PubMed

    Tanaka, Yuji; Shi, Dong; Kubota, Akira; Takano, Yoshimasa; Fuse, Nobuo; Yamato, Masayuki; Okano, Teruo; Nishida, Kohji

    2011-10-01

    Tissue engineering and transplantation of autogenic grafts have been widely investigated for solving problems on current allograft treatments (i.g., donor shortage and rejection). However, it is difficult to obtain an autogenic corneal stromal replacement that is composed of transparent, tough, and thick collagen constructs by current cell culture-based tissue engineering. Aim of this study is to develop transparent dermis for an autogenic corneal stroma transplantation. This study examined dehydration at 4-8°C and carbodiimide cross-linking on cloudy rabbit dermis (approx. 1.8%-3.8% light transmittance at 550 nm) for dermis optical clearing. Transparency of dehydrated rabbit dermis was founded to be approx. 37.9%-41.4% at 550 nm. Additional cross-linking treatment on dehydrated dermis prevented from swelling and clouding in saline, and improved its transparency to be 56.9% at 550 nm. Rabbit corneal epithelium was found to regenerate on optically cleared dermis in vitro. Furthermore, no abnormal biological response (i.e., inflammation, vascularization, and the barrier defect of epithelia) or no optical functional change on optically cleared dermis was observed during its 4-week autogenic transplantation into rabbit corneal stromal pocket.

  4. Reduction of titanium dioxide to metallic titanium conducted under the autogenic pressure of the reactants.

    PubMed

    Eshed, Michal; Irzh, Alexander; Gedanken, Aharon

    2009-08-03

    We report on a reaction to convert titanium dioxide to titanium. The reduction reaction was done under the autogenic pressure of the reactants at 750 degrees C for 5 h. The MgO, a by-product, was removed by acids to obtain pure metallic titanium.

  5. Self-reinnervated muscles lose autogenic length feedback, but intermuscular feedback can recover functional connectivity.

    PubMed

    Lyle, Mark A; Prilutsky, Boris I; Gregor, Robert J; Abelew, Thomas A; Nichols, T Richard

    2016-09-01

    In this study, we sought to identify sensory circuitry responsible for motor deficits or compensatory adaptations after peripheral nerve cut and repair. Self-reinnervation of the ankle extensor muscles abolishes the stretch reflex and increases ankle yielding during downslope walking, but it remains unknown whether this finding generalizes to other muscle groups and whether muscles become completely deafferented. In decerebrate cats at least 19 wk after nerve cut and repair, we examined the influence of quadriceps (Q) muscles' self-reinnervation on autogenic length feedback, as well as intermuscular length and force feedback, among the primary extensor muscles in the cat hindlimb. Effects of gastrocnemius and soleus self-reinnervation on intermuscular circuitry were also evaluated. We found that autogenic length feedback was lost after Q self-reinnervation, indicating that loss of the stretch reflex appears to be a generalizable consequence of muscle self-reinnervation. However, intermuscular force and length feedback, evoked from self-reinnervated muscles, was preserved in most of the interactions evaluated with similar relative inhibitory or excitatory magnitudes. These data indicate that intermuscular spinal reflex circuitry has the ability to regain functional connectivity, but the restoration is not absolute. Explanations for the recovery of intermuscular feedback are discussed, based on identified mechanisms responsible for lost autogenic length feedback. Functional implications, due to permanent loss of autogenic length feedback and potential for compensatory adaptations from preserved intermuscular feedback, are discussed.

  6. Differentiation of human embryonic stem cells into clinically amenable keratinocytes in an autogenic environment.

    PubMed

    Kidwai, Fahad K; Liu, Hua; Toh, Wei Seong; Fu, Xin; Jokhun, Doorgesh S; Movahednia, Mohammad M; Li, Mingming; Zou, Yu; Squier, Christopher A; Phan, Toan T; Cao, Tong

    2013-03-01

    Human embryonic stem cells (hESCs)-derived keratinocytes hold great clinical and research potential. However, the current techniques are hampered by the use of xenogenic components that limits their clinical application. Here we demonstrated an efficient differentiation of H9 hESCs (H9-hESCs) into keratinocytes (H9-Kert) with the minimum use of animal-derived materials. For differentiation, we established two microenvironment systems originated from H9-hESCs (autogenic microenvironment). These autogenic microenvironment systems consist of an autogenic coculture system (ACC) and an autogenic feeder-free system (AFF). In addition, we showed a stage-specific effect of Activin in promoting keratinocyte differentiation from H9-hESCs while repressing the expression of early neural markers in the ACC system. Furthermore, we also explained the effect of Activin in construction of the AFF system made up of extracellular matrix similar to basement membrane extracted from H9-hESC-derived fibroblasts. H9-Kert differentiated in both systems expressed keratinocyte markers at mRNA and protein levels. H9-Kert were also able to undergo terminal differentiation in high Ca(2+) medium. These findings support the transition toward the establishment of an animal-free microenvironment for successful differentiation of hESCs into keratinocytes for potential clinical application.

  7. Autogenic Feedback Training (Body FORTRAN) for Musically Gifted Students at Bonita Vista High School.

    ERIC Educational Resources Information Center

    Lane, John M.

    1982-01-01

    The Gifted Self-Understanding Assessment Battery (GSAB) was given to 34 (27 females, 7 males) music students (aged 15-17) at Bonita Vista High School in Chula Vista (California). Biofeedback training and assessment were followed by individual counseling for Autogenic Feedback Training (AFT) to achieve improvement of the individual's own well…

  8. Trait- and density-mediated indirect interactions initiated by an exotic invasive plant autogenic ecosystem engineer.

    PubMed

    Pearson, Dean E

    2010-10-01

    Indirect interactions are important for structuring ecological systems. However, research on indirect effects has been heavily biased toward top-down trophic interactions, and less is known about other indirect-interaction pathways. As autogenic ecosystem engineers, plants can serve as initiators of nontrophic indirect interactions that, like top-down pathways, can involve both trait-mediated indirect interactions (TMIIs) and density-mediated indirect interactions (DMIIs). Using microcosms, I examined a plant --> predator --> consumer interaction pathway involving the exotic autogenic ecosystem engineer Centaurea maculosa; native Dictyna spiders (which exhibit density and trait [web-building] responses to C. maculosa); Dictyna's insect prey, Urophora affinis; and Urophora's host plant (a secondary receiver species) to quantify DMIIs and TMIIs in an autogenic engineered pathway. Both DMIIs and TMIIs were strong enough to reduce Urophora populations, but only DMIIs, which were 4.3 times stronger than TMIIs, were strong enough to also reduce Urophora's fecundity and increase the fecundity of its host plant. Prior field studies support these results, suggesting that the differences between DMIIs and TMIIs are even stronger in nature. This study illustrates that autogenic ecosystem engineers can initiate powerful indirect interactions that generally parallel predator-initiated interactions but also differ in important functional ways.

  9. Apparatus for feeding fluidized bed incinerator, and method of autogenic operation of same

    SciTech Connect

    Nelson, J.F.

    1981-09-29

    This invention relates to an improved method and apparatus for continuous autogenic incineration of high-moisture easily friable combustible agglomerates in a fluidized-bed. The improvement comprises introducing the waste materials into the bed in a tube of air provided by supplemental air means which surrounds the in-bed feed means.

  10. Long-term follow-up of autogenous tooth bone graft blocks with dental implants.

    PubMed

    Kim, Young-Kyun; Pang, Kang-Mi; Yun, Pil-Young; Leem, Dae-Ho; Um, In-Woong

    2017-02-01

    Demineralized dentin matrix block (ABTB: Autogenous Tooth Bone Graft Block) is 3-D scaffold with same components and geometry with alveolar bone. ABTB is well incorporated and remodelled into cortico-cancellous bone with dental implant. The shape and volume were maintained with little marginal bone loss after average 44 months of follow-up.

  11. Autogenic Training and Hand Temperature Biofeedback in the Treatment of Migraine: A Preliminary Analysis.

    ERIC Educational Resources Information Center

    Jessup, B.; And Others

    The possibility of alleviating migraine headaches by autogenic relaxation training, with or without hand temperature biofeedback, was assessed. The study examined five independent groups in a bi-directional control group design. Volunteer migraine sufferers served as subjects, each participating for 12 weeks. The first four weeks of the study were…

  12. Long-term results with autogenous tissue repair of traumatic extremity vascular injuries.

    PubMed Central

    McCready, R A; Logan, N M; Daugherty, M E; Mattingly, S S; Crocker, C; Hyde, G L

    1987-01-01

    With extensive vascular injuries in which a vascular conduit is required, there is controversy as to whether an autogenous or prosthetic graft is preferable. The authors reviewed their experience with 91 extremity arterial injuries in which autogenous tissue was used to repair vascular injuries of the extremities. Twenty-two patients also had concomitant repair of associated venous injuries with autogenous vein grafts. Ten patients required amputations, despite patent grafts in five patients, because of severe muscle necrosis. Two patients had thrombosis of their vein grafts develop in the early postoperative period but did not require amputation. The authors identified only one late vein graft failure in a patient in whom an infected pseudoaneurysm developed. Three patients with extensive soft tissue injuries had infection develop in vein grafts, with subsequent massive bleeding that ultimately required arterial ligation. Among the 22 patients with repair of their venous injuries, occlusion of popliteal vein repairs was documented in two patients and suspected in three others. The remainder of patients had satisfactory results. The excellent results obtained in the vast majority of the authors' patients with extremity vascular injuries reinforces their preference for using autogenous tissue whenever a vascular conduit is required. Exceptions include patients with extensive soft tissue loss precluding adequate graft coverage, the repair of large vessels, and life-threatening emergencies when there is insufficient time to harvest and prepare a vein. PMID:3689017

  13. Sealing of cracks in cement using microencapsulated sodium silicate

    NASA Astrophysics Data System (ADS)

    Giannaros, P.; Kanellopoulos, A.; Al-Tabbaa, A.

    2016-08-01

    Cement-based materials possess an inherent autogenous self-healing capability allowing them to seal, and potentially heal, microcracks. This can be improved through the addition of microencapsulated healing agents for autonomic self-healing. The fundamental principle of this self-healing mechanism is that when cracks propagate in the cementitious matrix, they rupture the dispersed capsules and their content (cargo material) is released into the crack volume. Various healing agents have been explored in the literature for their efficacy to recover mechanical and durability properties in cementitious materials. In these materials, the healing agents are most commonly encapsulated in macrocontainers (e.g. glass tubes or capsules) and placed into the material. In this work, microencapsulated sodium silicate in both liquid and solid form was added to cement specimens. Sodium silicate reacts with the calcium hydroxide in hydrated cement paste to form calcium-silicate-hydrate gel that fills cracks. The effect of microcapsule addition on rheological and mechanical properties of cement is reported. It is observed that the microcapsule addition inhibits compressive strength development in cement and this is observed through a plateau in strength between 28 and 56 days. The improvement in crack-sealing for microcapsule-containing specimens is quantified through sorptivity measurements over a 28 day healing period. After just seven days, the addition of 4% microcapsules resulted in a reduction in sorptivity of up to 45% when compared to specimens without any microcapsule addition. A qualitative description of the reaction between the cargo material and the cementitious matrix is also provided using x-ray diffraction analysis.

  14. Shrinkage processes in standard-size Norway spruce wood specimens with different vulnerability to cavitation

    PubMed Central

    ROSNER, SABINE; KARLSSON, BO; KONNERTH, JOHANNES; HANSMANN, CHRISTIAN

    2011-01-01

    Summary The aim of this study was to observe the radial shrinkage of Norway spruce [Picea abies (L. Karst.)] trunkwood specimens with different hydraulic vulnerability to cavitation from the fully saturated state until the overall shrinkage reaches a stable value, and to relate wood shrinkage and recovery from shrinkage to cavitations of the water column inside the tracheids. Radial shrinkage processes in standard-size sapwood specimens (6 mm × 6 mm × 100 mm; radial, tangential and longitudinal) obtained at different positions within the trunk, representing different ages of the cambium, were compared. Cavitation events were assessed by acoustic emission (AE) testing, hydraulic vulnerability by the AE feature analysis and shrinkage was calculated from the changes in contact pressure between the 150 kHz AE transducer and the wood specimen. Two shrinkage processes were observed in both juvenile (annual rings 1 and 2) and mature wood (annual rings 17–19), the first one termed tension shrinkage and the second one cell wall shrinkage process, which started when most of the tracheids reached relative water contents below fiber saturation. Maximum tension shrinkage coincided with high-energy AEs, and the periods of shrinkage recovery could be traced to tension release due to cavitation. Juvenile wood, which was less sensitive to cavitation, had lower earlywood tracheid diameters and was less prone to deformation due to tensile strain than mature wood, showed a lower cell wall shrinkage, and thus total shrinkage. Earlywood lumen diameters and maximum tension shrinkage were strongly positively related to each other, meaning that bigger tracheids are more prone to deformation at the same water tension than the smaller tracheids. PMID:19797244

  15. Quantity effect of radial cracks on the cracking propagation behavior and the crack morphology.

    PubMed

    Chen, Jingjing; Xu, Jun; Liu, Bohan; Yao, Xuefeng; Li, Yibing

    2014-01-01

    In this letter, the quantity effect of radial cracks on the cracking propagation behavior as well as the circular crack generation on the impacted glass plate within the sandwiched glass sheets are experimentally investigated via high-speed photography system. Results show that the radial crack velocity on the backing glass layer decreases with the crack number under the same impact conditions during large quantities of repeated experiments. Thus, the "energy conversion factor" is suggested to elucidate the physical relation between the cracking number and the crack propagation speed. Besides, the number of radial crack also takes the determinative effect in the crack morphology of the impacted glass plate. This study may shed lights on understanding the cracking and propagation mechanism in laminated glass structures and provide useful tool to explore the impact information on the cracking debris.

  16. Application of autogenic training in patients with Ménière disease.

    PubMed

    Goto, Fumiyuki; Nakai, Kimiko; Ogawa, Kaoru

    2011-10-01

    Data are limited on the role of psychotherapy in the treatment of Ménière disease. We sought to document the effect of a psychotherapeutic technique known as autogenic training on clinical outcome in Ménière disease. Six patients with Ménière disease were studied. Retrospective chart review was conducted. All patients were refractory to conventional therapy and completed a course of autogenic training, which was offered as a complementary treatment. Autogenic training with initial psychological counseling was conducted by a clinical psychologist during 45-min sessions. Outcome measures assessed were the frequency of vertigo and functional levels 2 years after initiation of autogenic training. Functional levels were evaluated according to the 1995 guidelines of the American Academy of Otolaryngology-Head Neck Surgery (AAO-HNS). As a personality measure, we used the Maudsley Personality Inventory (MPI), devised by Eysenck, which measures neuroticism (N), extraversion (E), and propensity to lie (L). Five of six patients showed improved functional level after three to eight sessions of psychotherapy; hearing level did not change. The score of the N scale of the MPI was closely related to the number of psychotherapy sessions. Prognosis was evaluated based on the AAO-HNS reporting guidelines, as follows: A = 3, B = 1, C = 1, F = 1. The value of N in MPI was closely related to the number of psychological counseling sessions (R = 0.97, P < 0.05). In conclusion, autogenic training may enhance the mental well-being of patients with Ménière disease and improve clinical outcome.

  17. Elevated temperature crack growth

    NASA Technical Reports Server (NTRS)

    Kim, K. S.; Vanstone, R. H.; Malik, S. N.; Laflen, J. H.

    1988-01-01

    A study was performed to examine the applicability of path-independent (P-I) integrals to crack growth problems in hot section components of gas turbine aircraft engines. Alloy 718 was used and the experimental parameters included combined temperature and strain cycling, thermal gradients, elastic-plastic strain levels, and mean strains. A literature review was conducted of proposed P-I integrals, and those capable of analyzing hot section component problems were selected and programmed into the postprocessor of a finite element code. Detailed elastic-plastic finite element analyses were conducted to simulate crack growth and crack closure of the test specimen, and to evaluate the P-I integrals. It was shown that the selected P-I integrals are very effective for predicting crack growth for isothermal conditions.

  18. Elevated Temperature Crack Propagation

    NASA Technical Reports Server (NTRS)

    Orange, Thomas W.

    1994-01-01

    This paper is a summary of two NASA contracts on high temperature fatigue crack propagation in metals. The first evaluated the ability of fairly simple nonlinear fracture parameters to correlate crack propagation. Hastelloy-X specimens were tested under isothermal and thermomechanical cycling at temperatures up to 980 degrees C (1800 degrees F). The most successful correlating parameter was the crack tip opening displacement derived from the J-integral. The second evaluated the ability of several path-independent integrals to correlate crack propagation behavior. Inconel 718 specimens were tested under isothermal, thermomechanical, temperature gradient, and creep conditions at temperatures up to 650 degrees C (1200 degrees F). The integrals formulated by Blackburn and by Kishimoto correlated the data reasonably well under all test conditions.

  19. Elevated temperature crack propagation

    SciTech Connect

    Orange, T.W.

    1994-02-01

    This paper is a summary of two NASA contracts on high temperature fatigue crack propagation in metals. The first evaluated the ability of fairly simple nonlinear fracture parameters to correlate crack propagation. Hastelloy-X specimens were tested under isothermal and thermomechanical cycling at temperatures up to 980 degrees C (1800 degrees F). The most successful correlating parameter was the crack tip opening displacement derived from the J-integral. The second evaluated the ability of several path-independent integrals to correlate crack propagation behavior. Inconel 718 specimens were tested under isothermal, thermomechanical, temperature gradient, and creep conditions at temperatures up to 650 degrees C (1200 degrees F). The integrals formulated by Blackburn and by Kishimoto correlated the data reasonably well under all test conditions.

  20. Ethylene by Naphta Cracking

    ERIC Educational Resources Information Center

    Wiseman, Peter

    1977-01-01

    Presents a discussion of the manufacture of ethylene by thermal cracking of hydrocarbon feedstocks that is useful for introducing the subject of industrial chemistry into a chemistry curriculum. (MLH)

  1. Three-dimensional numerical simulation of weld solidification cracking

    NASA Astrophysics Data System (ADS)

    Wei, Y. H.; Dong, Z. B.; Liu, R. P.; Dong, Z. J.

    2005-04-01

    It is difficult to measure mechanical strain in the vicinity of a moving weld pool owing to the complex solidification process. Computational modelling of the welding process provides an effective method to study the stress/strain distributions of the weldment. In this paper, the driving force to weld solidification cracking, i.e. mechanical strain versus temperature at the trail of a weld molten pool, was modelled with the three-dimensional finite element analysis procedure. The dynamic stress/strain evolutions that contribute to the formation of solidification cracking have been calculated in the cracking susceptible temperature range. In the mechanical model, solidification effects, namely deformation in the weld pool, change of initial temperature for thermal stress/strain calculation, were treated by means of a dynamic element rebirth scheme. Solidification shrinkage was also taken into consideration in simulation. The results of comparison between the calculated driving force and the experimental measurements of the material resistance predict the susceptibility of solidification cracking.

  2. Inspecting cracks in foam insulation

    NASA Technical Reports Server (NTRS)

    Cambell, L. W.; Jung, G. K.

    1979-01-01

    Dye solution indicates extent of cracking by penetrating crack and showing original crack depth clearly. Solution comprised of methylene blue in denatured ethyl alcohol penetrates cracks completely and evaporates quickly and is suitable technique for usage in environmental or structural tests.

  3. Cracked Plain, Buried Craters

    NASA Technical Reports Server (NTRS)

    2004-01-01

    4 September 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a cracked plain in western Utopia Planitia. The three circular crack patterns indicate the location of three buried meteor impact craters. These landforms are located near 41.9oN, 275.9oW. The image covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates this scene from the lower left.

  4. Effect of modulated photo-activation on polymerization shrinkage behavior of dental restorative resin composites.

    PubMed

    Tauböck, Tobias T; Feilzer, Albert J; Buchalla, Wolfgang; Kleverlaan, Cornelis J; Krejci, Ivo; Attin, Thomas

    2014-08-01

    This study investigated the influence of modulated photo-activation on axial polymerization shrinkage, shrinkage force, and hardening of light- and dual-curing resin-based composites. Three light-curing resin composites (SDR bulk-fill, Esthet X flow, and Esthet X HD) and one dual-curing material (Rebilda DC) were subjected to different irradiation protocols with identical energy density (27 J cm(-2) ): high-intensity continuous light (HIC), low-intensity continuous light (LIC), soft-start (SS), and pulse-delay curing (PD). Axial shrinkage and shrinkage force of 1.5-mm-thick specimens were recorded in real time for 15 min using custom-made devices. Knoop hardness was determined at the end of the observation period. Statistical analysis revealed no significant differences among the curing protocols for both Knoop hardness and axial shrinkage, irrespective of the composite material. Pulse-delay curing generated the significantly lowest shrinkage forces within the three light-curing materials SDR bulk-fill, Esthet X flow, and Esthet X HD. High-intensity continuous light created the significantly highest shrinkage forces within Esthet X HD and Rebilda DC, and caused significantly higher forces than LIC within Esthet X flow. In conclusion, both the composite material and the applied curing protocol control shrinkage force formation. Pulse-delay curing decreases shrinkage forces compared with high-intensity continuous irradiation without affecting hardening and axial polymerization shrinkage.

  5. A Model for Prediction of Shrinkage Defects in Long and Short Freezing Range Materials

    SciTech Connect

    Reis, A.; Duarte, J. F.; Santos, A. D.; Magalhaes, A. B.; Houbaert, Y.

    2007-05-17

    The aim of the model presented in this paper is to capture the difference in solidification behaviour of long and short freezing materials. The shrinkage defects in short freezing materials tends to be internal, as porosity, while in long freezing materials these defects tend to be external in the form of surface depressions. To achieve this, a pressure drop based 3-D feeding flow model has been developed to evaluate shrinkage defects for casting alloys. A continuum formulation is used to describe the transport of mass, energy and momentum. It is assumed that during solidification the driving force for flow is shrinkage. A Darcy type source term has been included in the momentum equation to account for flow resistance in the mushy zone. A VOF free surface model has been used to describe shrinkage defects, i.e., external surface depressions and internal shrinkage porosities, while ensuring mass conservation. The model is used to calculate the shrinkage in a simple casting. The results shows internal and outside shrinkage defects depending on the freezing range of the metal. Short freezing range results mainly in internal shrinkage whereas the long freezing range results in external shrinkage. The expected shrinkage features are well described by the present model.

  6. A Model for Prediction of Shrinkage Defects in Long and Short Freezing Range Materials

    NASA Astrophysics Data System (ADS)

    Reis, A.; Xu, Zhi an; Duarte, J. F.; Santos, A. D.; Houbaert, Y.; Magalhães, A. B.

    2007-05-01

    The aim of the model presented in this paper is to capture the difference in solidification behaviour of long and short freezing materials. The shrinkage defects in short freezing materials tends to be internal, as porosity, while in long freezing materials these defects tend to be external in the form of surface depressions. To achieve this, a pressure drop based 3-D feeding flow model has been developed to evaluate shrinkage defects for casting alloys. A continuum formulation is used to describe the transport of mass, energy and momentum. It is assumed that during solidification the driving force for flow is shrinkage. A Darcy type source term has been included in the momentum equation to account for flow resistance in the mushy zone. A VOF free surface model has been used to describe shrinkage defects, i.e., external surface depressions and internal shrinkage porosities, while ensuring mass conservation. The model is used to calculate the shrinkage in a simple casting. The results shows internal and outside shrinkage defects depending on the freezing range of the metal. Short freezing range results mainly in internal shrinkage whereas the long freezing range results in external shrinkage. The expected shrinkage features are well described by the present model.

  7. Evaluation of the effect of crack closure on fatigue crack growth of simulated short cracks

    NASA Technical Reports Server (NTRS)

    Telesman, J.; Fisher, D. M.

    1984-01-01

    A test program was performed to determine the influence of crack closure on fatigue crack growth (FCG) rates of short cracks. By use of the standard compact tension specimen, test procedures were devised to evaluate closure loads in the wake of the crack behind its tip. The first procedure determined the magnitude of crack closure as a function of the fatigued crack wave by incrementally removing the contacting wake surfaces and measuring closure load at each increment. The second procedure used a low-high loading sequence to simulate short crack behavior. Based on the results, it was concluded that crack closure is not the major reason for the more rapid growth of short cracks as compared to long crack growth.

  8. Exploiting tumor shrinkage through temporal optimization of radiotherapy

    NASA Astrophysics Data System (ADS)

    Unkelbach, Jan; Craft, David; Hong, Theodore; Papp, Dávid; Ramakrishnan, Jagdish; Salari, Ehsan; Wolfgang, John; Bortfeld, Thomas

    2014-06-01

    In multi-stage radiotherapy, a patient is treated in several stages separated by weeks or months. This regimen has been motivated mostly by radiobiological considerations, but also provides an approach to reduce normal tissue dose by exploiting tumor shrinkage. The paper considers the optimal design of multi-stage treatments, motivated by the clinical management of large liver tumors for which normal liver dose constraints prohibit the administration of an ablative radiation dose in a single treatment. We introduce a dynamic tumor model that incorporates three factors: radiation induced cell kill, tumor shrinkage, and tumor cell repopulation. The design of multi-stage radiotherapy is formulated as a mathematical optimization problem in which the total dose to the normal tissue is minimized, subject to delivering the prescribed dose to the tumor. Based on the model, we gain insight into the optimal administration of radiation over time, i.e. the optimal treatment gaps and dose levels. We analyze treatments consisting of two stages in detail. The analysis confirms the intuition that the second stage should be delivered just before the tumor size reaches a minimum and repopulation overcompensates shrinking. Furthermore, it was found that, for a large range of model parameters, approximately one-third of the dose should be delivered in the first stage. The projected benefit of multi-stage treatments in terms of normal tissue sparing depends on model assumptions. However, the model predicts large dose reductions by more than a factor of 2 for plausible model parameters. The analysis of the tumor model suggests that substantial reduction in normal tissue dose can be achieved by exploiting tumor shrinkage via an optimal design of multi-stage treatments. This suggests taking a fresh look at multi-stage radiotherapy for selected disease sites where substantial tumor regression translates into reduced target volumes.

  9. Sonar target enhancement by shrinkage of incoherent wavelet coefficients.

    PubMed

    Hunter, Alan J; van Vossen, Robbert

    2014-01-01

    Background reverberation can obscure useful features of the target echo response in broadband low-frequency sonar images, adversely affecting detection and classification performance. This paper describes a resolution and phase-preserving means of separating the target response from the background reverberation noise using a coherence-based wavelet shrinkage method proposed recently for de-noising magnetic resonance images. The algorithm weights the image wavelet coefficients in proportion to their coherence between different looks under the assumption that the target response is more coherent than the background. The algorithm is demonstrated successfully on experimental synthetic aperture sonar data from a broadband low-frequency sonar developed for buried object detection.

  10. Laser guide star spot shrinkage for affordable wavefront sensors

    NASA Astrophysics Data System (ADS)

    Jahn, Wilfried; Hugot, Emmanuel; Fusco, Thierry; Neichel, Benoit; Ferrari, Marc; Correia, Carlos; Pueyo, Laurent; Dohlen, Kjetil; Pascal, Sandrine; Vola, Pascal; Sauvage, Jean-François; El Hadi, Kacem; Gach, Jean Luc

    2016-07-01

    Innovative optical designs allow tackling the spot elongation issues in Shack-Hartman based laser guide star wavefront sensors. We propose two solutions using either a combination of two arrays of freeform microlenses, or a combination of freeform optics, to perform a shrinkage of the laser spots as well as a magnification of the SH focal plane. These approaches will drastically reduce the number of needed pixels, thus making possible the use of existing detectors. We present the recent advances on this activity as well as the estimation of performance, linearity and sensitivity of the compressed system in presence of aberrations.

  11. Crack Driving Forces in a Multilayered Coating System for Ceramic Matrix Composite Substrates

    NASA Technical Reports Server (NTRS)

    Ghosn, Louis J.; Zhu, Dongming; Miller, Robert A.

    2005-01-01

    The effects of the top coating thickness, modulus and shrinkage strains on the crack driving forces for a baseline multilayer Yttria-Stabilized-Zirconia/Mullite/Si thermal and environment barrier coating (TEBC) system for SiC/SiC ceramic matrix composite substrates are determined for gas turbine applications. The crack driving forces increase with increasing modulus, and a low modulus thermal barrier coating material (below 10 GPa) will have no cracking issues under the thermal gradient condition analyzed. Since top coating sintering increases the crack driving forces with time, highly sintering resistant coatings are desirable to maintain a low tensile modulus and maintain a low crack driving force with time. Finite element results demonstrated that an advanced TEBC system, such as ZrO2/HfO2, which possesses improved sintering resistance and high temperature stability, exhibited excellent durability. A multi-vertical cracked structure with fine columnar spacing is an ideal strain tolerant coating capable of reducing the crack driving forces to an acceptable level even with a high modulus of 50 GPa.

  12. A fast-firing shrinkage rate controlled dilatometer using an infrared image furnace

    NASA Astrophysics Data System (ADS)

    Hackenberger, W. S.; Speyer, R. F.

    1994-03-01

    A novel dilatometer design is described for performing rate controlled sintering experiments on powder compacts. Previous rate controlled sintering systems, which control the shrinkage of a sintering compact, possessed only limited shrinkage rate control and shrinkage profile complexity due to the high thermal mass of conventional furnaces and dilatometers. The instrument described in this work features an infrared imaging furnace and a low thermal mass dilatometer assembly which together provide a very rapid temperature response. The system is capable of heating and cooling ceramic samples at up to 500 °C/min. Shrinkage control is accomplished using a modified, computer interfaced proportional-integral-derivative algorithm, and tests on glass-alumina composite samples demonstrated excellent shrinkage control with differences routinely less than 0.2% between the set point and actual shrinkage.

  13. Impaired decision-making and brain shrinkage in alcoholism.

    PubMed

    Le Berre, A-P; Rauchs, G; La Joie, R; Mézenge, F; Boudehent, C; Vabret, F; Segobin, S; Viader, F; Allain, P; Eustache, F; Pitel, A-L; Beaunieux, H

    2014-03-01

    Alcohol-dependent individuals usually favor instant gratification of alcohol use and ignore its long-term negative consequences, reflecting impaired decision-making. According to the somatic marker hypothesis, decision-making abilities are subtended by an extended brain network. As chronic alcohol consumption is known to be associated with brain shrinkage in this network, the present study investigated relationships between brain shrinkage and decision-making impairments in alcohol-dependent individuals early in abstinence using voxel-based morphometry. Thirty patients performed the Iowa Gambling Task and underwent a magnetic resonance imaging investigation (1.5T). Decision-making performances and brain data were compared with those of age-matched healthy controls. In the alcoholic group, a multiple regression analysis was conducted with two predictors (gray matter [GM] volume and decision-making measure) and two covariates (number of withdrawals and duration of alcoholism). Compared with controls, alcoholics had impaired decision-making and widespread reduced gray matter volume, especially in regions involved in decision-making. The regression analysis revealed links between high GM volume in the ventromedial prefrontal cortex, dorsal anterior cingulate cortex and right hippocampal formation, and high decision-making scores (P<0.001, uncorrected). Decision-making deficits in alcoholism may result from impairment of both emotional and cognitive networks.

  14. Response Predicting LTCC Firing Shrinkage: A Response Surface Analysis Study

    SciTech Connect

    Girardi, Michael; Barner, Gregg; Lopez, Cristie; Duncan, Brent; Zawicki, Larry

    2009-02-25

    The Low Temperature Cofired Ceramic (LTCC) technology is used in a variety of applications including military/space electronics, wireless communication, MEMS, medical and automotive electronics. The use of LTCC is growing due to the low cost of investment, short development time, good electrical and mechanical properties, high reliability, and flexibility in design integration (3 dimensional (3D) microstructures with cavities are possible)). The dimensional accuracy of the resulting x/y shrinkage of LTCC substrates is responsible for component assembly problems with the tolerance effect that increases in relation to the substrate size. Response Surface Analysis was used to predict product shrinkage based on specific process inputs (metal loading, layer count, lamination pressure, and tape thickness) with the ultimate goal to optimize manufacturing outputs (NC files, stencils, and screens) in achieving the final product design the first time. Three (3) regression models were developed for the DuPont 951 tape system with DuPont 5734 gold metallization based on green tape thickness.

  15. Internal curing with lightweight aggregate produced from biomass-derived waste

    SciTech Connect

    Lura, Pietro; Wyrzykowski, Mateusz; Tang, Clarence; Lehmann, Eberhard

    2014-05-01

    Shrinkage of concrete may lead to cracking and ultimately to a reduction of the service life of concrete structures. Among known methods for shrinkage mitigation, internal curing with porous aggregates was successfully utilized in the last couple of decades for decreasing autogenous and drying shrinkage. In this paper, the internal curing performance of pre-saturated lightweight aggregates produced from biomass-derived waste (bio-LWA) was studied. In the first part of this paper, the microstructure of the bio-LWA is investigated, with special focus on their pore structure and on their water absorption and desorption behavior. The bio-LWA has large porosity and coarse pore structure, which allows them to release the entrained water at early age and counteract self-desiccation and autogenous shrinkage. In the second part, the efficiency of internal curing in mortars incorporating the bio-LWA is examined by neutron tomography, internal relative humidity and autogenous deformation measurements.

  16. Crack propagation in Hastelloy X

    SciTech Connect

    Weerasooriya, T.; Strizak, J.P.

    1980-05-01

    The fatigue and creep crack growth rates of Hastelloy X were examined both in air and impure helium. Creep crack growth rate is higher in air and impure helium at 650/sup 0/C. Initial creep crack growth from the original sharp fatigue crack is by an intergranular mode of fracture. As the cracking accelerates at higher stress intensities, growth is by a mixed mode of both intergranular and transgranular fracture. Fatigue crack growth rate increases with increasing temperature and decreasing frequency for the range of stress intensities reported in the literature and is lower in impure helium than in air.

  17. Augmentation of arthrodesis in dogs using a free autogenous omental graft

    PubMed Central

    Ree, Jennifer J.; Baltzer, Wendy I.; Townsend, Katy L.

    2016-01-01

    A technique for using free autogenous omental grafting with arthrodesis in dogs is described and radiographic osseous union and complications after surgery are evaluated. This retrospective study matched body weight and procedure type for 8 cases of pancarpal arthrodesis, 4 cases of pantarsal arthrodesis, and 2 cases of partial tarsal arthrodesis in dogs with omental and cancellous bone autograft (OBG group) and with cancellous bone autograft alone (BG group). Radiographs were reviewed 9 to 12 weeks after surgery to compare scores of radiographic osseous union and it was found that the OBG group had higher scores than the BG group. The BG group had significantly more major complications that required re-operation for implant removal or treatment of a deep infection compared to the OBG group. Overall, free autogenous omental grafts may be used to augment arthrodesis in dogs without significant morbidity and further investigation of its use to reduce major complications and speed bone healing are warranted. PMID:27493282

  18. Combined use of autogenic therapy and biofeedback in training effective control of heart rate by humans

    NASA Technical Reports Server (NTRS)

    Cowings, P. S.

    1977-01-01

    Experiments were performed on 24 men and women (aged 20-27 yr) in three equal groups who were taught to control their own heart rates by autogenic training and biofeedback under dark and sound-isolated conditions. Group I was parasympathetic dominant, group II was sympathetic dominant, and group III consisted of parasympathetic-dominant subjects and controls who received only biofeedback of their own heart rates. The results corroborate three hypotheses: (1) subjects with para-sympathetic-dominant autonomic profiles perform in a way that is both qualitatively and quantitatively different from subjects with sympathetic-dominant autonomic profiles; (2) tests of interindividual variability yield data relevant to individual performance in visceral learning tasks; and (3) the combined use of autogenic training, biofeedback, and verbal feedback is suitable for conditioning large stable autonomic responses in humans.

  19. Success rates and immunologic responses of autogenic, allogenic, and xenogenic treatments to repair articular cartilage defects.

    PubMed

    Revell, Christopher M; Athanasiou, Kyriacos A

    2009-03-01

    This review examines current approaches available for articular cartilage repair, not only in terms of their regeneration potential, but also as a function of immunologic response. Autogenic repair techniques, including osteochondral plug transplantation, chondrocyte implantation, and microfracture, are the most widely accepted clinical treatment options due to the lack of immunogenic reactions, but only moderate graft success rates have been reported. Although suspended allogenic chondrocytes are shown to evoke an immune response upon implantation, allogenic osteochondral plugs and tissue-engineered grafts using allogenic chondrocytes exhibit a tolerable immunogenic response. Additionally, these repair techniques produce neotissue with success rates approaching those of currently available autogenic repair techniques, while simultaneously obviating their major hindrance of donor tissue scarcity. To date, limited research has been performed with xenogenic tissue, although several studies demonstrate the potential for its long-term success. This article focuses on the various treatment options for cartilage repair and their associated success rates and immunologic responses.

  20. Success Rates and Immunologic Responses of Autogenic, Allogenic, and Xenogenic Treatments to Repair Articular Cartilage Defects

    PubMed Central

    Revell, Christopher M.

    2009-01-01

    This review examines current approaches available for articular cartilage repair, not only in terms of their regeneration potential, but also as a function of immunologic response. Autogenic repair techniques, including osteochondral plug transplantation, chondrocyte implantation, and microfracture, are the most widely accepted clinical treatment options due to the lack of immunogenic reactions, but only moderate graft success rates have been reported. Although suspended allogenic chondrocytes are shown to evoke an immune response upon implantation, allogenic osteochondral plugs and tissue-engineered grafts using allogenic chondrocytes exhibit a tolerable immunogenic response. Additionally, these repair techniques produce neotissue with success rates approaching those of currently available autogenic repair techniques, while simultaneously obviating their major hindrance of donor tissue scarcity. To date, limited research has been performed with xenogenic tissue, although several studies demonstrate the potential for its long-term success. This article focuses on the various treatment options for cartilage repair and their associated success rates and immunologic responses. PMID:19063664

  1. Histologic assessment of a contiguous autogenous transplant in a human intrabony defect. A case report.

    PubMed

    Zubery, Y; Kozlovsky, A; Tal, H

    1993-01-01

    Increased blood supply, vital bone marrow cells, and minimal mobility may play a significant role in the success of osseous grafts, and are characteristics of the bone swaging grafting technique. As in all autogenous grafts, the risk of disease transmission is minimal. Previous reports of clinical success raise questions as to the type of tissue response to this procedure. This case report examines 8 months radiographic and histologic results of a clinically successful bone swaging graft.

  2. Operational Applications of Autogenic Feedback Training Exercise as a Treatment for Airsickness in the Military

    NASA Technical Reports Server (NTRS)

    Gebreyesus, Fiyore; Cowings, Patricia S.; Toscano, William B.

    2012-01-01

    Airsickness is experienced by about 50% of military aviators some time in their career. Aviators who suffer from recurrent episodes of airsickness are typically referred to the Naval Aerospace Medical Institute (NAMI) at Pensacola where they undergo extensive evaluation and 8 weeks of training in the Self-Paced Airsickness Desensitization (SPAD) program. Researchers at NASA Ames have developed an alternative mitigation training program, Autogenic Feedback Training Exercise (AFTE) that has demonstrated an 80% success rate for improving motion sickness tolerance.

  3. Sustainable exploitation and management of autogenic ecosystem engineers: application to oysters in Chesapeake Bay.

    PubMed

    Wilberg, Michael J; Wiedenmann, John R; Robinson, Jason M

    2013-06-01

    Autogenic ecosystem engineers are critically important parts of many marine and estuarine systems because of their substantial effect on ecosystem services. Oysters are of particular importance because of their capacity to modify coastal and estuarine habitats and the highly degraded status of their habitats worldwide. However, models to predict dynamics of ecosystem engineers have not previously included the effects of exploitation. We developed a linked population and habitat model for autogenic ecosystem engineers undergoing exploitation. We parameterized the model to represent eastern oyster (Crassostrea virginica) in upper Chesapeake Bay by selecting sets of parameter values that matched observed rates of change in abundance and habitat. We used the model to evaluate the effects of a range of management and restoration options including sustainability of historical fishing pressure, effectiveness of a newly enacted sanctuary program, and relative performance of two restoration approaches. In general, autogenic ecosystem engineers are expected to be substantially less resilient to fishing than an equivalent species that does not rely on itself for habitat. Historical fishing mortality rates in upper Chesapeake Bay for oysters were above the levels that would lead to extirpation. Reductions in fishing or closure of the fishery were projected to lead to long-term increases in abundance and habitat. For fisheries to become sustainable outside of sanctuaries, a substantial larval subsidy would be required from oysters within sanctuaries. Restoration efforts using high-relief reefs were predicted to allow recovery within a shorter period of time than low-relief reefs. Models such as ours, that allow for feedbacks between population and habitat dynamics, can be effective tools for guiding management and restoration of autogenic ecosystem engineers.

  4. Crack-free conditions in welding of glass by ultrashort laser pulse.

    PubMed

    Miyamoto, Isamu; Cvecek, Kristian; Schmidt, Michael

    2013-06-17

    The spatial distribution of the laser energy absorbed by nonlinear absorption process in bulk glass w(z) is determined and thermal cycles due to the successive ultrashort laser pulse (USLP) is simulated using w(z) based on the transient thermal conduction model. The thermal stress produced in internal melting of bulk glass by USLP is qualitatively analyzed based on a simple thermal stress model, and crack-free conditions are studied in glass having large coefficient of thermal expansion. In heating process, cracks are prevented when the laser pulse impinges into glass with temperatures higher than the softening temperature of glass. In cooling process, shrinkage stress is suppressed to prevent cracks, because the embedded molten pool produced by nonlinear absorption process behaves like an elastic body under the compressive stress field unlike the case of CW-laser welding where the molten pool having a free surface produced by linear absorption process is plastically deformed under the compressive stress field.

  5. Clinical, haematological and radiological evaluation of fragmented autogenous cortical bone grafting of radius in dogs.

    PubMed

    Grover, R K; Sobti, V K

    1998-07-01

    In eight clinically healthy dogs, a midshaft diaphyseal defect of 2 cm was created in the right radius ulna. This gap was maintained by fixing a four hole sherman bone plate on the radius. In four dogs, the gap was filled with autogenous cancellous bone grafts (2-5 mm in diameter) harvested from the proximal end of the tibia (group 1). In the remaining 4 dogs, the fracture gap was filled with autogenous cortical bone fragments (ACBF) of 2-5 mm diameter made from the same 2 cm piece of bone removed from the radius. While comparing various clinical observations, it appeared that healing of the wounds and bearing of the weight on the grafted limb in dogs subjected to ACBF graft were similar to those given autogenous cancellous bone graft. In radiographs, taken on the 30th day in group 1, a fairly good amount of callus was found emerging from fracture ends but the whole of the bone graft area was not covered by bony density even on the 60th day. In group 2 (ACBF), 45th day radiograph revealed that the callus from the fracture end was mixing up with the cortical bone fragments, and at the 60th day, the callus was clearly found invading the cortical bone fragments grafted in the fracture gap.

  6. Bone Formation in Maxillary Sinus Lift Using Autogenous Bone Graft at 2 and 6 Months.

    PubMed

    Netto, Henrique Duque; Miranda Chaves, Maria das Graças Alfonso; Aatrstrup, Beatriz; Guerra, Renata; Olate, Sergio

    2016-09-01

    The aim of this study is to compare the bone formation in maxillary sinus lift with an autogenous bone graft in histological evaluation at 2 or 6 months. A comparative study was designed where 10 patients with missing teeth bilaterally in the posterior zone of the maxilla were selected. Patients received a particulate autogenous bone graft under the same surgical conditions, selecting a site to collect a biopsy and histological study at two months and another at six months postoperatively. Histomorphometry was performed and were used Kolmogorov-Smirnov test, student's t-test and Spearman's correlation coefficient, considering a value of p<0.05. Differences were observed in inflammatory infiltrate and vascularization characteristics; however, the group analyzed at two months presented 38.12% ± 6.64 % of mineralized tissue, whereas the group studied at 6 months presented an average of 38.45 ± 9.27 %. There were no statistical differences between the groups. It is concluded that the bone formation may be similar in intrasinus particulate autogenous bone grafts in evaluations at two or six months; under these conditions, early installation of implants is viable.

  7. Differences in latent inhibition as a function of the autogenous-reactive OCD subtype.

    PubMed

    Lee, Han-Joo; Telch, Michael J

    2010-07-01

    We examined differences in a visual search-based latent inhibition (LI) task in 48 non-treatment seeking individuals diagnosed with obsessive-compulsive disorder (OCD) and 26 non-OCD controls, using a visual search-based LI task as a function of participants' primary obsessional presentation based on the autogenous-reactive subtype model of obsessions (Lee & Kwon, 2003; Lee & Telch, 2007). We hypothesized that LI would be significantly attenuated among OCD participants whose primary obsessions were characterized by aversive impulses, images, or thoughts with sexual, aggressive, blasphemous, and repulsive themes (autogenous obsessions) due to their weakened attentional inhibitory mechanisms and elevated schizotypal personality features, as compared with those whose primary obsessions were characterized by somewhat realistic aversive mental intrusions about contamination, mistakes, accidents, or disarray (reactive obsession) and non-OCD controls. Results showed that those primarily displaying autogenous obsessions failed to display LI, whereas those primarily displaying reactive obsessions and non-OCD controls displayed significant LI effects. Our data suggest that the magnitude of LI varies as a function of primary obsessional presentations among individuals with OCD.

  8. Bone Formation in Maxillary Sinus Lift Using Autogenous Bone Graft at 2 and 6 Months

    PubMed Central

    Netto, Henrique Duque; Miranda Chaves, Maria das Graças Alfonso; Aatrstrup, Beatriz; Guerra, Renata; Olate, Sergio

    2016-01-01

    SUMMARY The aim of this study is to compare the bone formation in maxillary sinus lift with an autogenous bone graft in histological evaluation at 2 or 6 months. A comparative study was designed where 10 patients with missing teeth bilaterally in the posterior zone of the maxilla were selected. Patients received a particulate autogenous bone graft under the same surgical conditions, selecting a site to collect a biopsy and histological study at two months and another at six months postoperatively. Histomorphometry was performed and were used Kolmogorov-Smirnov test, student’s t-test and Spearman’s correlation coefficient, considering a value of p<0.05. Differences were observed in inflammatory infiltrate and vascularization characteristics; however, the group analyzed at two months presented 38.12% ± 6.64 % of mineralized tissue, whereas the group studied at 6 months presented an average of 38.45 ± 9.27 %. There were no statistical differences between the groups. It is concluded that the bone formation may be similar in intrasinus particulate autogenous bone grafts in evaluations at two or six months; under these conditions, early installation of implants is viable. PMID:27867255

  9. Alternative method to treat oroantral communication and fistula with autogenous bone graft and platelet rich firbin

    PubMed Central

    Niedzielska, Iwona; Borgiel-Marek, Halina; Różanowski, Bartosz

    2016-01-01

    Background Removing a tooth from the jaw results in the occurrence of oroantral communication in beneficial anatomic conditions or in the case of a iatrogenic effect. Popularized treatments of the oroantral communication have numerous faults. Large bone defect eliminates the chance to introduce an implant. Purpose of this work was assessment of the usefulness of autogenous bone graft and PRF in normal bone regeneration in the site of oroantral communication. Material and Methods Bone regeneration in the site of oroantral communication was assessed in 20 patients. Bone defects were supplemented autogenous bone graft from mental protuberance in 14 cases and from oblique line in 6 cases. The graft was covered with a PRF membrane. Results In the study group in all cases closure of the oroantral communication was observed. The average width of the alveolar was 13 mm and the average height was 12.5 mm. In 3 patients an average increase of alveolar height of 1.5 mm was observed. Conclusions This method may be the best option to prepare alveolar for new implant and prosthetic solutions. Key words:Oroantral communication, oroantral fistula, autogenous bone graft, bone regeneration, platelet rich fibrin. PMID:27475687

  10. Cracking the Credit Hour

    ERIC Educational Resources Information Center

    Laitinen, Amy

    2012-01-01

    The basic currency of higher education--the credit hour--represents the root of many problems plaguing America's higher education system: the practice of measuring time rather than learning. "Cracking the Credit Hour" traces the history of this time-based unit, from the days of Andrew Carnegie to recent federal efforts to define a credit…

  11. Thermal cracking of retort oil

    SciTech Connect

    Dearth, J.D.; Smith, R.H.

    1980-10-14

    The thermal cracking of retort oil vapors in an elongated reactor is improved by passing the effluent oil vapors and gases from a retort to a thermal cracking unit before the temperature of the retort effluent falls below 680* F. This encourages the more desirable cracking reactions, increases the thermal efficiency of the process, and avoids preheater coking.

  12. Repair of long bone defects with demineralized bone matrix and autogenous bone composite

    PubMed Central

    Ozdemir, Mehmet T; Kir, Mustafa Ç

    2011-01-01

    Background: Repair of diaphyseal bone defects is a challenging problem for orthopedic surgeons. In large bone defects the quantity of harvested autogenous bone may not be sufficient to fill the gap and then the use of synthetic or allogenic grafts along with autogenous bone becomes mandatory to achieve compact filling. Finding the optimal graft mixture for treatment of large diaphyseal defects is an important goal in contemporary orthopedics and this was the main focus of this study. The aim of this study is to investigate the efficacy of demineralized bone matrix (DBM) and autogenous cancellous bone (ACB) graft composite in a rabbit bilateral ulna segmental defect model. Materials and Methods: Twenty-seven adult female rabbits were divided into five groups. A two-centimeter piece of long bone on the midshaft of the ulna was osteotomized and removed from the rabbits’ forearms. In group 1 (n=7) the defects were treated with ACB, in group 2 (n=7) with DBM, and in group 3 (n=7) with ACB and DBM in the ratio of 1:1. Groups 4 and 5, with three rabbits in each group, were the negative and positive controls, respectively. Twelve weeks after implantation the rabbits were sacrificed and union was evaluated with radiograph (Faxitron), dual-energy x-ray absorptiometry (DEXA), and histological methods (decalcified sectioning). Results: Union rates and the volume of new bone in the different groups were as follows: group 1 - 92.8% union and 78.6% new bone; group 2 - 72.2% union and 63.6% new bone; and group 3 - 100% union and 100% new bone. DEXA results (bone mineral density [BMD]) were as follows: group 1 - 0.164 g/cm2, group 2 - 0.138 g/cm2, and group 3 - 0.194 g/cm2. Conclusions: DBM serves as a graft extender or enhancer for autogenous graft and decreases the need of autogenous bone graft in the treatment of bone defects. In this study, the DBM and ACB composite facilitated the healing process. The union rate was better with the combination than with the use of any one of

  13. Crosslink-induced shrinkage of grafted Gaussian chains

    NASA Astrophysics Data System (ADS)

    Benetatos, Panayotis

    2014-04-01

    The statistical mechanics of polymers grafted on surfaces has been the subject of intense research activity because of many potential applications. In this paper, we analytically investigate the conformational changes caused by a single crosslink on two ideal (Gaussian) chains grafted onto a rigid planar surface. Both the crosslink and the surface reduce the number of allowed configurations. In the absence of the hard substrate, the sole effect of the crosslink is a reduction in the effective Kuhn length of a tethered chain. The crosslink-induced shrinkage (collapse) of the grafted chains (mushrooms) turns out to be a reduction in the variance of the distribution of the height of the chain rather than a reduction of the height itself.

  14. Analysis of gene set using shrinkage covariance matrix approach

    NASA Astrophysics Data System (ADS)

    Karjanto, Suryaefiza; Aripin, Rasimah

    2013-09-01

    Microarray methodology has been exploited for different applications such as gene discovery and disease diagnosis. This technology is also used for quantitative and highly parallel measurements of gene expression. Recently, microarrays have been one of main interests of statisticians because they provide a perfect example of the paradigms of modern statistics. In this study, the alternative approach to estimate the covariance matrix has been proposed to solve the high dimensionality problem in microarrays. The extension of traditional Hotelling's T2 statistic is constructed for determining the significant gene sets across experimental conditions using shrinkage approach. Real data sets were used as illustrations to compare the performance of the proposed methods with other methods. The results across the methods are consistent, implying that this approach provides an alternative to existing techniques.

  15. Hyperosmotic and isosmotic shrinkage differentially affect protein phosphorylation and ion transport.

    PubMed

    Koltsova, Svetlana V; Akimova, Olga A; Kotelevtsev, Sergei V; Grygorczyk, Ryszard; Orlov, Sergei N

    2012-02-01

    In the present work, we compared the outcome of hyperosmotic and isosmotic shrinkage on ion transport and protein phosphorylation in C11-MDCK cells resembling intercalated cells from collecting ducts and in vascular smooth muscle cells (VSMC) from the rat aorta. Hyperosmotic shrinkage was triggered by cell exposure to hypertonic medium, whereas isosmotic shrinkage was evoked by cell transfer from an hypoosmotic to an isosmotic environment. Despite a similar cell volume decrease of 40%-50%, the consequences of hyperosmotic and isosmotic shrinkage on cellular functions were sharply different. In C11-MDCK and VSMC, hyperosmotic shrinkage completely inhibited Na(+),K(+)-ATPase and Na(+),P(i) cotransport. In contrast, in both types of cells isosmotic shrinkage slightly increased rather than suppressed Na(+),K(+)-ATPase and did not change Na(+),P(i) cotransport. In C11-MDCK cells, phosphorylation of JNK1/2 and Erk1/2 mitogen-activated protein kinases was augmented in hyperosmotically shrunken cells by ∼7- and 2-fold, respectively, but was not affected in cells subjected to isosmotic shrinkage. These results demonstrate that the data obtained in cells subjected to hyperosmotic shrinkage cannot be considered as sufficient proof implicating cell volume perturbations in the regulation of cellular functions under isosmotic conditions.

  16. Modeling dental composite shrinkage by digital image correlation and finite element methods

    NASA Astrophysics Data System (ADS)

    Chen, Terry Yuan-Fang; Huang, Pin-Sheng; Chuang, Shu-Fen

    2014-10-01

    Dental composites are light-curable resin-based materials with an inherent defect of polymerization shrinkage which may cause tooth deflection and debonding of restorations. This study aimed to combine digital image correlation (DIC) and finite element analysis (FEA) to model the shrinkage behaviors under different light curing regimens. Extracted human molars were prepared with proximal cavities for composite restorations, and then divided into three groups to receive different light curing protocols: regular intensity, low intensity, and step-curing consisting of low and high intensities. For each tooth, the composite fillings were consecutively placed under both unbonded and bonded conditions. At first, the shrinkage of the unbonded restorations was analyzed by DIC and adopted as the setting of FEA. The simulated shrinkage behaviors obtained from FEA were further validated by the measurements in the bonded cases. The results showed that different light curing regimens affected the shrinkage in unbonded restorations, with regular intensity showing the greatest shrinkage strain on the top surface. The shrinkage centers in the bonded cases were located closer to the cavity floor than those in the unbonded cases, and were less affected by curing regimens. The FEA results showed that the stress was modulated by the accumulated light energy density, while step-curing may alleviate the tensile stress along the cavity walls. In this study, DIC provides a complete description of the polymerization shrinkage behaviors of dental composites, which may facilitate the stress analysis in the numerical investigation.

  17. Interpretation of Coal-Seam Sequestration Data Using a New Swelling and Shrinkage Model

    SciTech Connect

    Siriwardane, H.J.; Smith, D.H.

    2006-10-01

    This paper deals with the influence of swelling and shrinkage of coal on the production of methane from, and sequestration of carbon dioxide in, a coalbed reservoir. A three-dimensional swelling and shrinkage model was developed. It is based on constitutive equations that account for coupled fluid pressure-deformation behavior of a porous medium that undergoes swelling and shrinkage. The swelling and shrinkage strains are computed on the basis of the amounts of different gases (e.g., CO2, CH4) sorbed or desorbed. The amounts of sorption and desorption are computed from measured isotherms with the aid of the Ideal Adsorbed Solution model for mixed gases. The permeability of the reservoir is modified according to the swelling-shrinkage model. The paper presents numerical results for the influence of swelling and shrinkage on reservoir performance during injection of carbon dioxide. The paper includes results from a number of examples, and analysis of a field injection into a coal seam at a site in the San Juan basin. Results show that with the incorporation of swelling and shrinkage into the analysis, it is possible to get a better history-match of production data. Results also show that coal swelling can reduce the injection volumes of carbon dioxide significantly. The interpretation of field data with the new swelling-shrinkage model shows that the coal swelling during carbon dioxide sequestration in coal-seams is an important factor that can influence field performance.

  18. Prediction of Shrinkage Pore Volume Fraction Using a Dimensionless Niyama Criterion

    NASA Astrophysics Data System (ADS)

    Carlson, Kent D.; Beckermann, Christoph

    2009-01-01

    A method is presented to use a dimensionless form of the well-known Niyama criterion to directly predict the amount of shrinkage porosity that forms during solidification of metal alloy castings. The main advancement offered by this method is that it avoids the need to know the threshold Niyama value below which shrinkage porosity forms; such threshold values are generally unknown and alloy dependent. The dimensionless criterion accounts for both the local thermal conditions (as in the original Niyama criterion) and the properties and solidification characteristics of the alloy. Once a dimensionless Niyama criterion value is obtained from casting simulation results, the corresponding shrinkage pore volume fraction can be determined knowing only the solid fraction-temperature curve and the total solidification shrinkage of the alloy. Curves providing the shrinkage pore volume percentage as a function of the dimensionless Niyama criterion are given for WCB steel, aluminum alloy A356, and magnesium alloy AZ91D. The present method is used in a general-purpose casting simulation software package to predict shrinkage porosity in three-dimensional (3-D) castings. Comparisons between simulated and experimental shrinkage porosity results for a WCB steel plate casting demonstrate that this method can reasonably predict shrinkage. Additional simulations for magnesium alloy AZ91D illustrate that this method is applicable to a wide variety of alloys and casting conditions.

  19. A Review of Crack Closure

    DTIC Science & Technology

    1984-04-01

    OVERLOAD EFFECTS [27,32,36,55,65,80-94] 104 4.3 SHORT CRACK BEHAVIOUR 113 4.4 SURFACE CRACK BEHAVIOUR 116 4.5 EFFECT OF RESIDUAL STRESS 117 4.6...Compressive Stresses Developed 16 on a Growing Fatigue Crack During a Constant Amplitude Cyclic Load Control Test. 4 Plastic Zone and Residual Compressive... Stresses Developed 18 on a Saw Cut Sharp Crack During a Constant Amplitude Cyclic Load Control Test. Residual Stresses Developed in the Plane of Crack

  20. Thermoelectrically controlled device for studies of temperature-induced corneal shrinkage

    NASA Astrophysics Data System (ADS)

    Borja, David; Manns, Fabrice; Fernandez, Viviana; Lamar, Peggy; Soederberg, Per G.; Parel, Jean-Marie A.

    2002-06-01

    The purpose of this study was to design and calibrate a device to measure the dynamics of thermal shrinkage in corneal and scleral strips. The apparatus consists of a thermoelectric cell controlled by a temperature controller designed to generate temperatures up to 90 degree(s)C in rectangular corneal strips; a copper cuvette filled with Dextran solution that holds the corneal strip and a displacement sensor that measures the change in length of the tissue during heat-induced shrinkage. The device was tested on corneal tissue from Florida Eye-Bank eyes that were cut into 2x4mm rectangular strips. Preliminary results indicate that our system can reproducibly create and accurately measure thermally induced corneal shrinkage. Shrinkage experiments will be used to optimize laser parameters for corneal shrinkage during laser thermokeratoplasty and laser scleral buckling.

  1. Monitoring of collagen shrinkage by use of second harmonic generation microscopy

    NASA Astrophysics Data System (ADS)

    Lin, Sung-Jan; Chen, Jau-Shiuh; Lo, Wen; Sun, Yen; Chen, Wei-Liang; Chan, Jung-Yi; Tan, Hsin-Yuan; Lin, Wei-Chou; Hsu, Chih-Jung; Young, Tai-Horng; Jee, Shiou-Hwa; Dong, Chen-Yuan

    2006-02-01

    Thermal treatment induced collagen shrinkage has a great number of applications in medical practice. Clinically, the there is lack of reliable non-invasive methods to quantify the shrinkage. Overt treatment by heat application can lead to devastating results. We investigate the serial changes of collagen shrinkage by thermal treatment of rat tail tendons. The change in length is correlated with the finding in second harmonic generation microscopy and histology. Rat tail tendon shortens progressively during initial thermal treatment. After a certain point in time, the length then remains almost constant despite further thermal treatment. The intensity of second harmonic generation signals also progressively decreases initially and then remains merely detectable upon further thermal treatment. It prompts us to develop a mathematic model to quantify the dependence of collagen shrinkage on changes of SHG intensity. Our results show that SHG intensity can be used to predict the degree of collagen shrinkage during thermal treatment for biomedical applications.

  2. Sudden bending of cracked laminates

    NASA Technical Reports Server (NTRS)

    Sih, G. C.; Chen, E. P.

    1980-01-01

    A dynamic approximate laminated plate theory is developed with emphasis placed on obtaining effective solution for the crack configuration where the 1/square root of r stress singularity and the condition of plane strain are preserved. The radial distance r is measured from the crack edge. The results obtained show that the crack moment intensity tends to decrease as the crack length to laminate plate thickness is increased. Hence, a laminated plate has the desirable feature of stabilizing a through crack as it increases its length at constant load. Also, the level of the average load intensity transmitted to a through crack can be reduced by making the inner layers to be stiffer than the outer layers. The present theory, although approximate, is useful for analyzing laminate failure to crack propagation under dynamic load conditions.

  3. [Effect of hypnosis and autogenic training on acral circulation and coping with the illness in patients with progressive scleroderma].

    PubMed

    Seikowski, K; Weber, B; Haustein, U F

    1995-02-01

    In 12 patients with systemic sclerosis the influence of hypnosis and autogenic training on the acral blood circulation and the coping with the disease was investigated in a pilot study. In the first step significant increases in the skin temperature of the finger (mean +/- SD: 3.9 +/- 1.2 degrees C) could be found after relaxation hypnosis. In the second step six patients (study group) gained experience with autogenic training. The other six patients served as control group. In the study group, the skin temperature of the fingers (short-term effect) was significantly higher than in the control group (1.9 +/- 1.0 degrees C). Long-term effects of the autogenic training (mean acral rewarning time, duration and course of the Raynaud attacks, acral lesions of the hands, psychosomatic status of complaints, type of relation to the disease as precondition for coping with the disease) were not found within the relatively short follow-up period of 4 months. Two patients, however, reported that they could shorten the duration of Raynaud attacks by autogenic training. In our patients heterogenicity and an increased score of multiple psychosomatic complaints were registered at the outset. As far as the type of relation to the disease is concerned, the patients could be assessed as almost adapted. Hypnosis and autogenic training can be recommended as complementary therapy in systemic sclerosis.

  4. Autogenous bone graft combined with polylactic polyglycolic acid polymer for treatment of dehiscence around immediate dental implants.

    PubMed

    Hassan, Khalid S

    2009-11-01

    The use of composite bone grafts in dehiscence defects around immediate dental implants are aimed at improving the outcome of the regenerative process. The present study was designed to evaluate the efficacy of combinations of autogenous bone graft with a synthetic copolymer polylactic and polyglycolic acid (Fisiograft) on bone healing of buccal dehiscence defects around immediate dental implants. Sixteen adult male patients who each received an immediate implant for a single tooth replacement at a maxillary anterior or premolar site were included in this study. Patients were divided into 2 groups. One group received immediate dental implants augmented with autogenous bone graft combined with Fisiograft. The other group received immediate dental implants augmented with autogenous bone graft alone. The results revealed that both treatment modalities led to significant improvements for the primary outcome regarding bone fill as well as a significant reduction of probing pocket depth and gain of attachment level. Moreover, there were slightly statistically significant differences between the groups. In conclusion, the combination of autogenous bone graft and Fisiograft showed a slight superiority to autogenous bone graft alone, suggesting that it could be an optimum bone substitute for treatment of dehiscence around immediate dental implant.

  5. Elevated temperature crack growth

    NASA Technical Reports Server (NTRS)

    Malik, S. N.; Vanstone, R. H.; Kim, K. S.; Laflen, J. H.

    1985-01-01

    The purpose is to determine the ability of currently available P-I integrals to correlate fatigue crack propagation under conditions that simulate the turbojet engine combustor liner environment. The utility of advanced fracture mechanics measurements will also be evaluated during the course of the program. To date, an appropriate specimen design, a crack displacement measurement method, and boundary condition simulation in the computational model of the specimen were achieved. Alloy 718 was selected as an analog material based on its ability to simulate high temperature behavior at lower temperatures. Tensile and cyclic tests were run at several strain rates so that an appropriate constitutive model could be developed. Suitable P-I integrals were programmed into a finite element post-processor for eventual comparison with experimental data.

  6. Elevated temperature crack growth

    NASA Technical Reports Server (NTRS)

    Yau, J. F.; Malik, S. N.; Kim, K. S.; Vanstone, R. H.; Laflen, J. H.

    1985-01-01

    The objective of the Elevated Temperature Crack Growth Project is to evaluate proposed nonlinear fracture mechanics methods for application to combustor liners of aircraft gas turbine engines. During the first year of this program, proposed path-independent (P-I) integrals were reviewed for such applications. Several P-I integrals were implemented into a finite-element postprocessor which was developed and verified as part of the work. Alloy 718 was selected as the analog material for use in the forthcoming experimental work. A buttonhead, single-edge notch specimen was designed and verified for use in elevated-temperature strain control testing with significant inelastic strains. A crack mouth opening displacement measurement device was developed for further use.

  7. Statistical crack mechanics

    SciTech Connect

    Dienes, J.K.

    1983-01-01

    An alternative to the use of plasticity theory to characterize the inelastic behavior of solids is to represent the flaws by statistical methods. We have taken such an approach to study fragmentation because it offers a number of advantages. Foremost among these is that, by considering the effects of flaws, it becomes possible to address the underlying physics directly. For example, we have been able to explain why rocks exhibit large strain-rate effects (a consequence of the finite growth rate of cracks), why a spherical explosive imbedded in oil shale produces a cavity with a nearly square section (opening of bedding cracks) and why propellants may detonate following low-speed impact (a consequence of frictional hot spots).

  8. Cracked and Pitted Plain

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-536, 6 November 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a typical view--at 1.5 meters (5 feet) per pixel--of surfaces in far western Utopia Planitia. In this region, the plains have developed cracks and pit chains arranged in a polygonal pattern. The pits form by collapse along the trend of a previously-formed crack. This picture is located near 45.0oN, 275.4oW. This April 2003 image covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.

  9. Subcritical crack growth in marble

    NASA Astrophysics Data System (ADS)

    Nara, Yoshitaka; Nishida, Yuki; Toshinori, Ii; Harui, Tomoki; Tanaka, Mayu; Kashiwaya, Koki

    2016-04-01

    It is essential to study time-dependent deformation and fracturing in various rock materials to prevent natural hazards related to the failure of a rock mass. In addition, information of time-dependent fracturing is essential to ensure the long-term stability of a rock mass surrounding various structures. Subcritical crack growth is one of the main causes of time-dependent fracturing in rock. It is known that subcritical crack growth is influenced by not only stress but also surrounding environment. Studies of subcritical crack growth have been widely conducted for silicate rocks such as igneous rocks and sandstones. By contrast, information of subcritical crack growth in carbonate rocks is not enough. Specifically, influence of surrounding environment on subcritical crack growth in carbonate rock should be clarified to ensure the long-term stability of a rock mass. In this study, subcritical crack growth in marble was investigated. Especially, the influence of the temperature, relative humidity and water on subcritical crack growth in marble is investigated. As rock samples, marbles obtained in Skopje-City in Macedonia and Carrara-City in Italy were used. To measure subcritical crack growth, we used the load relaxation method of the double-torsion (DT) test. All measurements by DT test were conducted under controlled temperature and relative humidity. For both marbles, it was shown that the crack velocity in marble in air increased with increasing relative humidity at a constant temperature. Additionally, the crack velocity in water was much higher than that in air. It was also found that the crack velocity increased with increasing temperature. It is considered that temperature and water have significant influences on subcritical crack growth in marble. For Carrara marble in air, it was recognized that the value of subcritical crack growth index became low when the crack velocity was higher than 10-4 m/s. This is similar to Region II of subcritical crack growth

  10. Utopia Cracks and Polygons

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-339, 23 April 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a pattern of polygonal cracks and aligned, elliptical pits in western Utopia Planitia. The picture covers an area about 3 km (about 1.9 mi) wide near 44.9oN, 274.7oW. Sunlight illuminates the scene from the left.

  11. Distributed Password Cracking

    DTIC Science & Technology

    2009-12-01

    conduit to this significant source of processing power and John the Ripper is the key. BOINC is a distributed data processing system that...processed without changing significant portions of the structure. John the Ripper is a password cracking program that takes a password file and...strength of their password security policy. This thesis goes into detail on the inner workings of BOINC, John the Ripper , and the merger of the two

  12. Layer model for long-term deflection analysis of cracked reinforced concrete bending members

    NASA Astrophysics Data System (ADS)

    Bacinskas, Darius; Kaklauskas, Gintaris; Gribniak, Viktor; Sung, Wen-Pei; Shih, Ming-Hsiang

    2012-05-01

    A numerical technique has been proposed for the long-term deformation analysis of reinforced concrete members subjected to a bending moment. The technique based on the layer approach in a simple and rational way deals with such complex issues as concrete cracking and tension-stiffening as well as creep and shrinkage. The approach uses the material stress-strain relationships for compressive concrete, cracked tensile concrete and steel. Such effects as linear and nonlinear creep, cracking, tension-stiffening as well as the reduction in concrete tension strength due to sustained loading have been taken into account. The shrinkage effect has been modeled by means of adequate actions of axial force and bending moment. A statistical deflection calculation analysis has been carried out for 322 experimental reinforced concrete beams reported in the literature. The comparative analysis of the experimental and the modeling results has shown that the proposed technique has well captured the time-deflection behavior of reinforced concrete flexural members. The results of the predictions by ACI 318 and Eurocode 2 design codes have been also discussed.

  13. Elasto-plastic fracture mechanics of crack growth in soil

    NASA Astrophysics Data System (ADS)

    Hallett, P. D.; Newson, T. A.

    2003-04-01

    A predominant variable in soil structure formation and degradation is crack propagation. Empirical models exist to predict fracture but these do not describe the underlying physical processes. Theoretical fracture mechanics models have been applied to soil, but most are not applicable when soil is in a wet, plastic state. Since the onset of crack formation in soil tends to occur in this condition, physically sound elasto-plastic fracture mechanics approaches are long overdue. We address this weakness by applying a new elasto-plastic fracture mechanics approach to describe crack formation in plastic soil. Samples are fractured using a deep-notch (modified 4-point) bend test, with data on load transmission, sample bending, crack growth, and crack mouth opening collected to assess the crack opening angle (COA), the crack tip opening angle (CTOA) and the plastic energy dissipation rate (Dpl). These are all material properties that can be used directly to predict and describe crack propagation. CTOA will be used to discuss the results here, although a full description of the other parameters will be provided in the conference presentation. It provides a powerful parameter for describing soil cracking since CTOA is induced by soil shrinkage (an easily measured parameter) and can be used to describe elasto-plastic fracture in finite element modelling packages. The test variables we have studied to date are clay platelet orientation, soil texture, clay mineralogy, and pore water salinity. All samples were formed by consolidating a soil slurry with a 120 kPa vertical stress. Tests on pure kaolinite showed that platelet orientation did not affect CTOA which was 0.23 ± 0.02 for both conditions. Soil texture did have a marked influence, however, with silica sand:kaolinite mixes of 20:80 and 40:60 reducing CTOA to 0.14 ± 0.02 and 0.12 ± 0.01 respectively. These lower values of CTOA indicate that less strain is required to induce fracture when the amount of clay is lowered

  14. Investigation of Cracks Found in Helicopter Longerons

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Baughman, James M.; Wallace, Terryl A.

    2009-01-01

    Four cracked longerons, containing a total of eight cracks, were provided for study. Cracked regions were cut from the longerons. Load was applied to open the cracks, enabling crack surface examination. Examination revealed that crack propagation was driven by fatigue loading in all eight cases. Fatigue crack initiation appears to have occurred on the top edge of the longerons near geometric changes that affect component bending stiffness. Additionally, metallurigical analysis has revealed a local depletion in alloying elements in the crack initiation regions that may be a contributing factor. Fatigue crack propagation appeared to be initially driven by opening-mode loading, but at a crack length of approximately 0.5 inches (12.7 mm), there is evidence of mixed-mode crack loading. For the longest cracks studied, shear-mode displacements destroyed crack-surface features of interest over significant portions of the crack surfaces.

  15. A theory for the origin of a self-replicating chemical system. II - Computer simulation of the autogen

    NASA Technical Reports Server (NTRS)

    White, D. H.; Raab, M. S.

    1982-01-01

    In order to better understand the feasibility and limitations of the autogen (White 1980), a computer simulation based on the fluctuating clay environment was used to test whether autocatalytic growth would occur under various conditions. The results suggest that overall accuracies of replication and translation in the range of 90% and 10%, and protoenzyme turnover numbers of 10-120 monomers/protoenzyme/day are adequate for exponential growth. Nucleation of the components of the autogen from random background oligomers would be extremely rapid if oligomers lengths 2-6 were adequately functional, whereas oligomer lengths much greater than 10 are prohibited. The autogen would most likely nucleate and grow to dominance either rapidly (10-100 cycles of roughly 1 day each) or not at all.

  16. Effect of autogenic relaxation on depression among menopausal women in rural areas of Thiruvallur District (Tamil Nadu).

    PubMed

    Sujithra, S

    2014-01-01

    An experimental study was conducted among 60 menopausal women, 30 each in experimental and control group who met inclusion criteria. The menopausal women were identified in both the groups and level of depression was assessed using Cornell Dysthmia rating scale. Simple random sampling technique by lottery method was used for selecting the sample. Autogenic relaxation was practiced by the menopausal women for four weeks. The findings revealed that in experimental group, after intervention of autogenic relaxation on depression among menopausal women, 23 (76.7%) had mild depression. There was a statistically significant effectiveness in experimental group at the level of p < 0.05. There was a statistically significant association between the effectiveness of autogenic relaxation on depression among menopausal women in the post-experimental group with the type of family at the level of p < 0.05.

  17. Importance of shrinkage in empirical bayes estimates for diagnostics: problems and solutions.

    PubMed

    Savic, Radojka M; Karlsson, Mats O

    2009-09-01

    Empirical Bayes ("post hoc") estimates (EBEs) of etas provide modelers with diagnostics: the EBEs themselves, individual prediction (IPRED), and residual errors (individual weighted residual (IWRES)). When data are uninformative at the individual level, the EBE distribution will shrink towards zero (eta-shrinkage, quantified as 1-SD(eta (EBE))/omega), IPREDs towards the corresponding observations, and IWRES towards zero (epsilon-shrinkage, quantified as 1-SD(IWRES)). These diagnostics are widely used in pharmacokinetic (PK) pharmacodynamic (PD) modeling; we investigate here their usefulness in the presence of shrinkage. Datasets were simulated from a range of PK PD models, EBEs estimated in non-linear mixed effects modeling based on the true or a misspecified model, and desired diagnostics evaluated both qualitatively and quantitatively. Identified consequences of eta-shrinkage on EBE-based model diagnostics include non-normal and/or asymmetric distribution of EBEs with their mean values ("ETABAR") significantly different from zero, even for a correctly specified model; EBE-EBE correlations and covariate relationships may be masked, falsely induced, or the shape of the true relationship distorted. Consequences of epsilon-shrinkage included low power of IPRED and IWRES to diagnose structural and residual error model misspecification, respectively. EBE-based diagnostics should be interpreted with caution whenever substantial eta- or epsilon-shrinkage exists (usually greater than 20% to 30%). Reporting the magnitude of eta- and epsilon-shrinkage will facilitate the informed use and interpretation of EBE-based diagnostics.

  18. Experimental and theoretical modeling of shrinkage damage formation in fiber composites

    NASA Astrophysics Data System (ADS)

    Korotkov, V. N.; Rozenberg, B. A.

    1998-03-01

    The cure of a thermoset matrix in the formation of composites is always accompanied by chemical shrinkage that generates internal stresses. In composites with high fiber content, the matrix is cured under three-dimensionally constrained conditions. The results of the previous experimental and theoretical modeling of formation of shrinkage damage under these conditions in epoxy-amine systems are briefly discussed. The effect of the model geometry (tube and plate models), scale factor, cure schedule, and chemical structure of composites is analyzed. A theoretical model for predicting the possibility of formation of shrinkage damage in fiber composites is proposed. A regular square structure was considered. Analysis showed that the maximum level of shrinkage stress in the matrix at the ultimate fiber fraction ϕ+ was close to the stress level σ+ in an experimental long tube model, where the formation of shrinkage damage took place. The experimental results for the short tube model showed that the shrinkage damage in epoxy-amine systems occurred up to approximately σ+/3. The damage development took place within the whole range of fiber content from ϕ+ to ϕ* (where the shrinkage stress level was about σ+/3). In the long tube model, cohesive defects always nucleated inside the matrix. The damage grew, reached the inner surface of the tube, and then extended as adhesive debondings. A similar situation is expected in composites with a high fiber content. The damage considered is local, and the total monolithic character of a composite product is conserved.

  19. Effect of plasma arc curing on polymerization shrinkage of orthodontic adhesive resins.

    PubMed

    Bang, H-C; Lim, B-S; Yoon, T-H; Lee, Y-K; Kim, C-W

    2004-08-01

    The purpose of this study was to evaluate the polymerization shrinkage of three orthodontic adhesive resins when polymerized with a high-energy plasma arc light (1340 mW cm(-2)) and a conventional halogen light (500 mW cm(-2)), and to correlate the polymerization shrinkage with the degree of conversion. To equalize the total light energy delivered to the adhesive resin, irradiation time was varied between 3 or 6 s for a plasma arc-curing unit, and 8 or 16 s for a halogen light-curing unit. The polymerization shrinkage of adhesive resins during the light-curing process was measured using a computer-controlled mercury dilatometer and the degree of conversion was measured using Fourier transform infrared spectroscopy. A plasma arccuring unit produced significantly lower polymerization shrinkage than a halogen light-curing unit when the equivalent total light energy was irradiated to the orthodontic adhesive resins (P < 0.05). The magnitude of polymerization shrinkage was significantly different depending on the kind of adhesive resins (P < 0.05), but there was no significant correlation between the filler fraction and the polymerization shrinkage (r2 = 0.039). There was strong correlation (r2 = 0.787) between the polymerization shrinkage and the degree of conversion with a halogen light-curing unit, but poor correlation (r2 = 0.377) was observed with a plasma arc-curing unit.

  20. Cognitive therapy for autogenous and reactive obsessions: clinical and cognitive outcomes at post-treatment and 1-year follow-up.

    PubMed

    Belloch, Amparo; Cabedo, Elena; Carrió, Carmen; Larsson, Christina

    2010-08-01

    This study provides data about the differential effectiveness of cognitive therapy (CT) for obsessive-compulsive disorder (OCD) symptom presentation. Two OCD manifestations, autogenous and reactive, are considered. Seventy OCD patients started CT; 81.40% completed it and 72.85% were available 1 year later. Fifteen of the 57 treatment completers had autogenous obsessions, whereas 33 had reactive obsessions. Nine patients had both obsession modalities. Reactive patients were more severe, as they scored higher on thought suppression and on the dysfunctional beliefs of intolerance to uncertainty and perfectionism. Autogenous patients scored higher on the over-importance of thoughts beliefs. Although CT was effective in reducing OCD severity and the ascription to dysfunctional beliefs and neutralizing strategies in both the autogenous and the reactive patients, a significantly better outcome was observed for the autogenous patients, both at post-treatment (with 73.33% recovering versus 33.33% for reactives) and 1 year later.

  1. Evaluation of ABM/P-15 versus autogenous bone in an ovine lumbar interbody fusion model

    PubMed Central

    Sherman, Blake P.; Lindley, Emily M.; Turner, A. Simon; Seim III, Howard B.; Benedict, James; Burger, Evalina L.

    2010-01-01

    A prospective, randomized study was performed in an ovine model to compare the efficacy of an anorganic bovine-derived hydroxyapatite matrix combined with a synthetic 15 amino acid residue (ABM/P-15) in facilitating lumbar interbody fusion when compared with autogenous bone harvested from the iliac crest. P-15 is a biomimetic to the cell-binding site of Type-I collagen for bone-forming cells. When combined with ABM, it creates the necessary scaffold to initiate cell invasion, binding, and subsequent osteogenesis. In this study, six adult ewes underwent anterior-lateral interbody fusion at L3/L4 and L4/L5 using PEEK interbody rings filled with autogenous bone at one level and ABM/P-15 at the other level and no additional instrumentation. Clinical CT scans were obtained at 3 and 6 months; micro-CT scans and histomorphometry analyses were performed after euthanization at 6 months. Clinical CT scan analysis showed that all autograft and ABM/P-15 treated levels had radiographically fused outside of the rings at the 3-month study time point. Although the clinical CT scans of the autograft treatment group showed significantly better fusion within the PEEK rings than ABM/P-15 at 3 months, micro-CT scans, clinical CT scans, and histomorphometric analyses showed there were no statistical differences between the two treatment groups at 6 months. Thus, ABM/P-15 was as successful as autogenous bone graft in producing lumbar spinal fusion in an ovine model, and it should be further evaluated in clinical studies. PMID:20694847

  2. Evaluation of ABM/P-15 versus autogenous bone in an ovine lumbar interbody fusion model.

    PubMed

    Sherman, Blake P; Lindley, Emily M; Turner, A Simon; Seim, Howard B; Benedict, James; Burger, Evalina L; Patel, Vikas V

    2010-12-01

    A prospective, randomized study was performed in an ovine model to compare the efficacy of an anorganic bovine-derived hydroxyapatite matrix combined with a synthetic 15 amino acid residue (ABM/P-15) in facilitating lumbar interbody fusion when compared with autogenous bone harvested from the iliac crest. P-15 is a biomimetic to the cell-binding site of Type-I collagen for bone-forming cells. When combined with ABM, it creates the necessary scaffold to initiate cell invasion, binding, and subsequent osteogenesis. In this study, six adult ewes underwent anterior-lateral interbody fusion at L3/L4 and L4/L5 using PEEK interbody rings filled with autogenous bone at one level and ABM/P-15 at the other level and no additional instrumentation. Clinical CT scans were obtained at 3 and 6 months; micro-CT scans and histomorphometry analyses were performed after euthanization at 6 months. Clinical CT scan analysis showed that all autograft and ABM/P-15 treated levels had radiographically fused outside of the rings at the 3-month study time point. Although the clinical CT scans of the autograft treatment group showed significantly better fusion within the PEEK rings than ABM/P-15 at 3 months, micro-CT scans, clinical CT scans, and histomorphometric analyses showed there were no statistical differences between the two treatment groups at 6 months. Thus, ABM/P-15 was as successful as autogenous bone graft in producing lumbar spinal fusion in an ovine model, and it should be further evaluated in clinical studies.

  3. Extensor-tendons reconstruction using autogenous palmaris longus tendon grafting for rheumatoid arthritis patients

    PubMed Central

    Chu, Po-Jung; Lee, Hung-Maan; Hou, Yao-Tung; Hung, Sheng-Tsai; Chen, Jung-Kuei; Shih, Jui-Tien

    2008-01-01

    Background The purpose of the study is to retrospectively review the clinical outcome of our study population of middle-aged RA patients who had suffered extensor-tendon rupture. We reported the outcome of autogenous palmaris tendon grafting of multiple extensor tendons at wrist level in 14 middle-aged rheumatoid patients. Methods Between Feb. 2000 to Feb. 2004, thirty-six ruptured wrist level extensor tendons were reconstructed in fourteen rheumatoid patients (11 women and three men) using autogenous palmaris longus tendon as a free interposition graft. In each case, the evaluation was based on both subjective and objective criteria, including the range of MCP joint flexion after surgery, the extension lag at the metacarpophalangeal joint before and after surgery, and the ability of the patient to work. Results and Discussion The average of follow-up was 54.1 months (range, 40 to 72 months). The average range of MCP joint flexion after reconstruction was 66°. The extension lag at the metacarpophalangeal joint significantly improved from a preoperative mean of 38° (range, 25°–60°) to a postoperative mean of 16° (range, 0°–30°). Subjectively all patients were satisfied with the clinical results, and achieved a return to their level of ability before tendon rupture. We found good functional results in our series of interposition grafting using palmaris longus to reconstruct extensor tendon defects in the rheumatoid patients. Conclusion Reconstruction for multiple tendon ruptures is a salvage procedure that is often associated with extensor lag and impairment of overall function. Early aggressive treatment of extensor tendon reconstruction using autogenous palmaris longus tendon as a free interposition graft in the rheumatoid wrist is another viable option to achieve good clinical functional result. PMID:18435845

  4. Numerical Model Predictions for Autogenic Fluvial Terrace Formation and Comparison to Natural River Valleys

    NASA Astrophysics Data System (ADS)

    Limaye, A. B. S.; Lamb, M. P.

    2015-12-01

    Terraces cut into bedrock (strath) and sediment (fill-cut) offer key constraints on river evolution over millennial timescales, and are often interpreted to form during phases of increased river vertical incision driven by changes in climate or tectonics. Yet all actively meandering channels evolve their shapes through spatial and temporal changes in lateral erosion rates. Therefore, the sparsest requirement for a meandering river to generate terraces is that the intrinsically unsteady lateral erosion rate be coupled with relief generation by vertical incision, which need not be unsteady. In principle, this basic mechanism for terrace formation by meandering rivers should be possible in all fluvial environments, including for valleys with strath or fill-cut terraces, and may overprint signals from external drivers. We have used a numerical model of a vertically incising, meandering river to identify the age and geometric properties of autogenic terraces. Simulations indicate that autogenic terraces form with a recurrence timescale, set by the rate of relief generation, which may overlap with timescales for climate change. The autogenic terraces also have predictable geometries that can include slope proportional to the ratio of vertical incision rate to lateral erosion rate, pairing, and continuous along-valley extent. We compare these simulation results to data for terrace age and geometry from several well studied natural river valleys that span a wide range in terrace sizes and geometries, rock types, tectonic settings, incision rates, and hypothesized formation mechanisms. In cases, terrace age and geometric properties are consistent with formation by meandering with constant vertical incision rates. These similarities suggest that efforts to distinguish terraces that record signals from climatic and tectonic drivers are best focused on environments where terrace ages and geometries are far different than would be predicted by a constant vertical incision model.

  5. Augmentation of the rat jaw with autogeneic cortico-cancellous bone grafts and guided tissue regeneration.

    PubMed

    Donos, Nikolaos; Kostopoulos, Lambros; Karring, Thorkild

    2002-04-01

    The aim of the present study was to evaluate the effect of augmenting the maxillary alveolar ridge and the lateral aspect of the mandible with onlay autogeneic cortico-cancellous bone grafts that were covered with e-PTFE membranes. The experiment was carried out in 51 rats. In 15 rats, the edentulous maxillary jaw between the incisor and the first molar was augmented by means of an autogeneic ischiac bone graft that was fixed with a gold-coated microimplant. In one side, the graft was covered with an e-PTFE membrane, while the other side, which served as control, was treated without a membrane. In the other 36 rats, the lateral aspect of the mandible was augmented in both sides by means of an autogeneic ischiac bone graft that was fixed with a gold-coated or a titanium microimplant. In one side, the augmented area was covered with an e-PTFE membrane, while the contralateral side was treated without a membrane. Histological analysis at 60, 120 and 180 days after augmentation of the maxilla showed that, in the case of the test sites (where most of the membranes were either exposed or lost), the bone grafts presented extensive resorption and there was a lack of bone continuity between the graft and the recipient site. Similar findings were made at the non-membrane-treated control sides. In the case of augmentation of the mandible with membranes, the bone grafts were not resorbed, but were integrated into newly formed bone at the recipient site. In the control sides, the grafts presented varying degrees of resorption and integration into the recipient bone. It is concluded that, in comparison to bone grafting alone, onlay ischiac bone grafting combined with guided tissue regeneration eliminates the risk of bone graft resorption and ensures integration of the graft into newly formed bone at the recipient site, provided that closure of the operated area can be maintained during healing.

  6. Combination of thermal cracking with vacuum distillation of cracked tar

    SciTech Connect

    Telyashev, G.G.; Gimaev, R.N.; Makhov, A.F.; Usmanov, R.M.; Baimbetov, A.M.; Vafin, I.A.

    1987-11-01

    A method of obtaining greater amounts of distillate feedstocks from the heavy gasoil recovered by vacuum distillation of the products of thermal cracking of petroleum resids was examined. At the Novo-Ufa Petroleum Refinery, a two-furnace thermal cracking unit was reconstructed, adding a vacuum section for distillation of the cracked tar. A simplified flow plan of this unit is shown. Vacuum resid from atmospheric-vacuum tubestill units is heated in double-pipe heat exchangers, using heat from the gasoil and cracked tar. The new method makes it possible to curtail production of boiler fuel, expand the resources of feed, and improve the quality of petroleum coke.

  7. On the Crack Bifurcation and Fanning of Crack Growth Data

    NASA Technical Reports Server (NTRS)

    Forman, Royce G.; Zanganeh, Mohammad

    2015-01-01

    Crack growth data obtained from ASTM load shedding method for different R values show some fanning especially for aluminum alloys. It is believed by the authors and it has been shown before that the observed fanning is due to the crack bifurcation occurs in the near threshold region which is a function of intrinsic properties of the alloy. Therefore, validity of the ASTM load shedding test procedure and results is confirmed. However, this position has been argued by some experimentalists who believe the fanning is an artifact of the test procedure and thus the obtained results are invalid. It has been shown that using a special test procedure such as using compressively pre-cracked specimens will eliminate the fanning effect. Since not using the fanned data fit can result in a significantly lower calculated cyclic life, design of a component, particularly for rotorcraft and propeller systems will considerably be impacted and therefore this study is of paramount importance. In this effort both test procedures i.e. ASTM load shedding and the proposed compressive pre-cracking have been used to study the fatigue crack growth behavior of compact tension specimens made of aluminum alloy 2524-T3. Fatigue crack growth paths have been closely observed using SEM machines to investigate the effects of compression pre-cracking on the crack bifurcation behavior. The results of this study will shed a light on resolving the existing argument by better understanding of near threshold fatigue crack growth behavior.

  8. Bone healing around nanocrystalline hydroxyapatite, deproteinized bovine bone mineral, biphasic calcium phosphate, and autogenous bone in mandibular bone defects.

    PubMed

    Broggini, Nina; Bosshardt, Dieter D; Jensen, Simon S; Bornstein, Michael M; Wang, Chun-Cheng; Buser, Daniel

    2015-10-01

    The individual healing profile of a given bone substitute with respect to osteogenic potential and substitution rate must be considered when selecting adjunctive grafting materials for bone regeneration procedures. In this study, standardized mandibular defects in minipigs were filled with nanocrystalline hydroxyapatite (HA-SiO), deproteinized bovine bone mineral (DBBM), biphasic calcium phosphate (BCP) with a 60/40% HA/β-TCP (BCP 60/40) ratio, or particulate autogenous bone (A) for histological and histomorphometric analysis. At 2 weeks, percent filler amongst the test groups (DBBM (35.65%), HA-SiO (34.47%), followed by BCP 60/40 (23.64%)) was significantly higher than the more rapidly substituted autogenous bone (17.1%). Autogenous bone yielded significantly more new bone (21.81%) over all test groups (4.91%-7.74%) and significantly more osteoid (5.53%) than BCP 60/40 (3%) and DBBM (2.25%). At 8 weeks, percent filler amongst the test groups (DBBM (31.6%), HA-SiO (31.23%), followed by BCP 60/40 (23.65%)) demonstrated a similar pattern and was again significantly higher as compared to autogenous bone (9.29%). Autogenous bone again exhibited statistically significantly greater new bone (55.13%) over HA-SiO (40.62%), BCP 60/40 (40.21%), and DBBM (36.35%). These results suggest that the osteogenic potential of HA-SiO and BCP is inferior when compared to autogenous bone. However, in instances where a low substitution rate is desired to maintain the volume stability of augmented sites, particularly in the esthetic zone, HA-SiO and DBBM may be favored.

  9. Identifying autogenic sedimentation in fluvial-deltaic stratigraphy: Evaluating the effect of outcrop-quality data on the compensation statistic

    NASA Astrophysics Data System (ADS)

    Trampush, S. M.; Hajek, E. A.; Straub, K. M.; Chamberlin, E. P.

    2017-01-01

    Stratigraphy preserves an extensive record of Earth-surface dynamics acting over a range of scales in a variety of environments. To take advantage of this record, we first must distinguish depositional patterns that arise due to intrinsic (i.e., autogenic) landscape dynamics from sedimentation that results from changes in climate, tectonic, or eustatic boundary conditions. The compensation statistic is a quantitative tool that has been used to estimate scales and patterns of autogenic sedimentation in experimental deposits; it has been applied to a few outcrop studies, but its sensitivity to data limitations common in natural deposits remains unconstrained. To explore how the compensation statistic may be applied to outcrop data, we evaluate the sensitivity of the tool to stratigraphic data sets limited in extent and resolution by subsampling an autogenic experimental deposit to create pseudo-outcrop-scale data sets. Results show that for data sets more than 3 times thicker than a characteristic depositional element (e.g., channel or lobe), the compensation statistics that can be used reliably constrain the maximum scale of autogenic sedimentation even for low-resolution data sets. Additionally, we show that autogenic sedimentation patterns may be characterized as persistent, random, or compensational using the compensation statistic when data sets are high resolution. We demonstrate how these measurements can be applied to natural data sets with comparative case studies of two fluvial and two deltaic outcrops. These case studies show how the compensation statistic can provide insight into what controls the maximum scale of autogenic sedimentation in different systems and how landscape dynamics can produce organized sedimentation patterns over long time scales.

  10. Effect of Oxygen Concentration on Autogenous Ignition Temperature and Pneumatic Impact Ignitability of Nonmetallic Materials

    NASA Technical Reports Server (NTRS)

    Smith, Sarah

    2009-01-01

    Extensive test data exist on the ignitability of nonmetallic materials in pure oxygen, but these characteristics are not as well understood for lesser oxygen concentrations. In this study, autogenous ignition temperature testing and pneumatic impact testing were used to better understand the effects of oxygen concentration on ignition of nonmetallic materials. Tests were performed using oxygen concentrations of 21, 34, 45, and 100 %. The following materials were tested: PTFE Teflon(Registered Trademark), Buna-N, Silicone, Zytel(Registered Trademark) 42, Viton(registered Trademark) A, and Vespel(Registered Trademark) SP-21.

  11. Two cases of panic disorder treated with autogenic training and in vivo exposure without medication.

    PubMed

    Sakai, M; Takeichi, M

    1996-12-01

    The aim of this study was to use autogenic training in combination with in vivo exposure in the behavioral treatment of panic disorder without medication. Two cases of panic disorder with agoraphobic avoidance were presented. Case 1 was a 33 year old married female who exhibited mild panic symptoms, and case 2 was a 23 year old single male who had severe panic symptoms. Both subjects were successfully treated with the combination of these two techniques. Treatment effects were maintained for 9 years as a follow up in case 1, and for 4 years in case 2.

  12. [Essential hypertension and stress. When do yoga, psychotherapy and autogenic training help?].

    PubMed

    Herrmann, J M

    2002-05-09

    Psychosocial factors play an important role in the development and course of essential hypertension, although "stress" can account for only 10% of blood pressure variance. A variety of psychotherapeutic interventions, such as relaxation techniques (autogenic training or progressive muscular relaxation), behavioral therapy or biofeedback techniques, can lower elevated blood pressure by an average of 10 mmHg (systolic) and 5 mmHg (diastolic). As a "secondary effect", such measures may also prompt the hypertensive to adopt a more health-conscious lifestyle.

  13. Monitoring of pre-release cracks in prestressed concrete using fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Abdel-Jaber, Hiba; Glisic, Branko

    2015-04-01

    Prestressed concrete experiences low to no tensile stresses, which results in limiting the occurrence of cracks in prestressed concrete structures. However, the nature of construction of these structures requires the concrete not to be subjected to the compressive force from the prestressing tendons until after it has gained sufficient compressive strength. Although the structure is not subjected to any dead or live load during this period, it is influenced by shrinkage and thermal variations. Thus, the concrete can experience tensile stresses before the required compressive strength has been attained, which can result in the occurrence of "pre-release" cracks. Such cracks are visually closed after the transfer of the prestressing force. However, structural capacity and behavior can be impacted if cracks are not sufficiently closed. This paper researches a method for the verification of the status of pre-release cracks after transfer of the prestressing force, and it is oriented towards achievement of Level IV Structural Health Monitoring (SHM). The method relies on measurements from parallel long-gauge fiber optic sensors embedded in the concrete prior to pouring. The same sensor network is used for the detection and characterization of cracks, as well as the monitoring of the prestressing force transfer and the determination of the extent of closure of pre-release cracks. This paper outlines the researched method and presents its application to a real-life structure, the southeast leg of Streicker Bridge on the Princeton University campus. The application structure is a curved continuous girder that was constructed in 2009. Its deck experienced four pre-release cracks that were closed beyond the critical limits based on the results of this study.

  14. Preventing Cracking of Anodized Coatings

    NASA Technical Reports Server (NTRS)

    He, Charles C.; Heslin, Thomas M.

    1995-01-01

    Anodized coatings have been used as optical and thermal surfaces in spacecraft. Particulate contamination from cracked coatings is a concern for many applications. The major cause for the cracking is the difference in the coefficient of thermal expansion between the oxide coatings and the aluminum substrate. The loss of water when the coating is exposed to a vacuum also could induce cracking of the coating. Hot-water sealing was identified as the major cause for the cracking of the coatings because of the large temperature change when the parts were immersed in boiling water and the water was absorbed in the coating. when the hot-water sealing process was eliminated, the cracking resistance of the anodized coatings was greatly improved. Also, it was found that dyed black coatings were more susceptible than clear coatings to cracking during thermo-vacuum cyclings.

  15. Super-resolution optical telescopes with local light diffraction shrinkage

    PubMed Central

    Wang, Changtao; Tang, Dongliang; Wang, Yanqin; Zhao, Zeyu; Wang, Jiong; Pu, Mingbo; Zhang, Yudong; Yan, Wei; Gao, Ping; Luo, Xiangang

    2015-01-01

    Suffering from giant size of objective lenses and infeasible manipulations of distant targets, telescopes could not seek helps from present super-resolution imaging, such as scanning near-field optical microscopy, perfect lens and stimulated emission depletion microscopy. In this paper, local light diffraction shrinkage associated with optical super-oscillatory phenomenon is proposed for real-time and optically restoring super-resolution imaging information in a telescope system. It is found that fine target features concealed in diffraction-limited optical images of a telescope could be observed in a small local field of view, benefiting from a relayed metasurface-based super-oscillatory imaging optics in which some local Fourier components beyond the cut-off frequency of telescope could be restored. As experimental examples, a minimal resolution to 0.55 of Rayleigh criterion is obtained, and imaging complex targets and large targets by superimposing multiple local fields of views are demonstrated as well. This investigation provides an access for real-time, incoherent and super-resolution telescopes without the manipulation of distant targets. More importantly, it gives counterintuitive evidence to the common knowledge that relayed optics could not deliver more imaging details than objective systems. PMID:26677820

  16. Laser-induced scleral shrinkage for refractive surgery

    NASA Astrophysics Data System (ADS)

    Ren, Qiushi; Simon, Gabriel; Parel, Jean-Marie A.; Shen, Jin-Hui

    1994-06-01

    We investigate the laser refractive scleroplasty (LRS) as a potential minimal-invasive method for correcting post-operative astigmatism. The scleral shrinkage near limbus was induced on 6 cadaver eyes using a 200 micrometers fiber optic probe coupled to a pulsed Ho:YAG laser. The diameter of the treatment spot was 0.8 mm. The output energy measured at tip was 60.2+/- 0.6 mJ. The treatments consisted of multiple sector patterns placed along the major axis of astigmatism parallel to the limbus, and round patterns placed along the limbus. Three treatment spots were applied on each side of the sector. The separation among sectors and limbus is 1 mm. Keratometry and topography of the cornea were measured after each sector or round pattern treatment. Effect of 5 and 10 pulses at each treatment spot were compared. Histology was performed to evaluate laser tissue damage. The major axis of astigmatism was shifted 90 degrees after the sector pattern treatment and amount of dioptric change increased when adding a new treatment or using more treatment pulses. However, the spherical equivalent of the eyes was essentially unchanged. The keratometry of the corneas remained the same after the round pattern treatment. Laser refractive scleroplasty may be applied for the correction of post-operative astigmatism.

  17. Super-resolution optical telescopes with local light diffraction shrinkage.

    PubMed

    Wang, Changtao; Tang, Dongliang; Wang, Yanqin; Zhao, Zeyu; Wang, Jiong; Pu, Mingbo; Zhang, Yudong; Yan, Wei; Gao, Ping; Luo, Xiangang

    2015-12-18

    Suffering from giant size of objective lenses and infeasible manipulations of distant targets, telescopes could not seek helps from present super-resolution imaging, such as scanning near-field optical microscopy, perfect lens and stimulated emission depletion microscopy. In this paper, local light diffraction shrinkage associated with optical super-oscillatory phenomenon is proposed for real-time and optically restoring super-resolution imaging information in a telescope system. It is found that fine target features concealed in diffraction-limited optical images of a telescope could be observed in a small local field of view, benefiting from a relayed metasurface-based super-oscillatory imaging optics in which some local Fourier components beyond the cut-off frequency of telescope could be restored. As experimental examples, a minimal resolution to 0.55 of Rayleigh criterion is obtained, and imaging complex targets and large targets by superimposing multiple local fields of views are demonstrated as well. This investigation provides an access for real-time, incoherent and super-resolution telescopes without the manipulation of distant targets. More importantly, it gives counterintuitive evidence to the common knowledge that relayed optics could not deliver more imaging details than objective systems.

  18. Super-resolution optical telescopes with local light diffraction shrinkage

    NASA Astrophysics Data System (ADS)

    Wang, Changtao; Tang, Dongliang; Wang, Yanqin; Zhao, Zeyu; Wang, Jiong; Pu, Mingbo; Zhang, Yudong; Yan, Wei; Gao, Ping; Luo, Xiangang

    2015-12-01

    Suffering from giant size of objective lenses and infeasible manipulations of distant targets, telescopes could not seek helps from present super-resolution imaging, such as scanning near-field optical microscopy, perfect lens and stimulated emission depletion microscopy. In this paper, local light diffraction shrinkage associated with optical super-oscillatory phenomenon is proposed for real-time and optically restoring super-resolution imaging information in a telescope system. It is found that fine target features concealed in diffraction-limited optical images of a telescope could be observed in a small local field of view, benefiting from a relayed metasurface-based super-oscillatory imaging optics in which some local Fourier components beyond the cut-off frequency of telescope could be restored. As experimental examples, a minimal resolution to 0.55 of Rayleigh criterion is obtained, and imaging complex targets and large targets by superimposing multiple local fields of views are demonstrated as well. This investigation provides an access for real-time, incoherent and super-resolution telescopes without the manipulation of distant targets. More importantly, it gives counterintuitive evidence to the common knowledge that relayed optics could not deliver more imaging details than objective systems.

  19. INTER-GROUP IMAGE REGISTRATION BY HIERARCHICAL GRAPH SHRINKAGE.

    PubMed

    Ying, Shihui; Wu, Guorong; Liao, Shu; Shen, Dinggang

    2013-12-31

    In this paper, we propose a novel inter-group image registration method to register different groups of images (e.g., young and elderly brains) simultaneously. Specifically, we use a hierarchical two-level graph to model the distribution of entire images on the manifold, with intra-graph representing the image distribution in each group and the inter-graph describing the relationship between two groups. Then the procedure of inter-group registration is formulated as a dynamic evolution of graph shrinkage. The advantage of our method is that the topology of entire image distribution is explored to guide the image registration. In this way, each image coordinates with its neighboring images on the manifold to deform towards the population center, by following the deformation pathway simultaneously optimized within the graph. Our proposed method has been also compared with other state-of-the-art inter-group registration methods, where our method achieves better registration results in terms of registration accuracy and robustness.

  20. Gene Network Reconstruction using Global-Local Shrinkage Priors*

    PubMed Central

    Leday, Gwenaël G.R.; de Gunst, Mathisca C.M.; Kpogbezan, Gino B.; van der Vaart, Aad W.; van Wieringen, Wessel N.; van de Wiel, Mark A.

    2016-01-01

    Reconstructing a gene network from high-throughput molecular data is an important but challenging task, as the number of parameters to estimate easily is much larger than the sample size. A conventional remedy is to regularize or penalize the model likelihood. In network models, this is often done locally in the neighbourhood of each node or gene. However, estimation of the many regularization parameters is often difficult and can result in large statistical uncertainties. In this paper we propose to combine local regularization with global shrinkage of the regularization parameters to borrow strength between genes and improve inference. We employ a simple Bayesian model with non-sparse, conjugate priors to facilitate the use of fast variational approximations to posteriors. We discuss empirical Bayes estimation of hyper-parameters of the priors, and propose a novel approach to rank-based posterior thresholding. Using extensive model- and data-based simulations, we demonstrate that the proposed inference strategy outperforms popular (sparse) methods, yields more stable edges, and is more reproducible. The proposed method, termed ShrinkNet, is then applied to Glioblastoma to investigate the interactions between genes associated with patient survival.

  1. Effects of drying conditions, admixtures and specimen size on shrinkage strains

    SciTech Connect

    Al-Saleh, Saleh A. . E-mail: alsaleh@dr.com; Al-Zaid, Rajeh Z.

    2006-10-15

    The paper presents the results of an experimental investigation on the effects of drying conditions, specimen size and presence of plasticizing admixture on the development of shrinkage strains. The measurements are taken in a harsh (50 deg. C and 5% R.H.) and a moderate environment (28 deg. C and 50% R.H.). The results include strain development at various levels of cross sections of concrete prisms. The drying conditions are found to be the dominant parameter affecting the shrinkage strain development particularly in specimens of smaller sizes. The effect of plasticizing admixture on shrinkage strains is negligible.

  2. Analysis of the status of pre-release cracks in prestressed concrete structures using long-gauge sensors

    NASA Astrophysics Data System (ADS)

    Abdel-Jaber, H.; Glisic, B.

    2015-02-01

    Prestressed structures experience limited tensile stresses in concrete, which limits or completely eliminates the occurrence of cracks. However, in some cases, large tensile stresses can develop during the early age of the concrete due to thermal gradients and shrinkage effects. Such stresses can cause early-age cracks, termed ‘pre-release cracks’, which occur prior to the transfer of the prestressing force. When the prestressing force is applied to the cross-section, it is assumed that partial or full closure of the cracks occurs by virtue of the force transfer through the cracked cross-section. Verification of the closure of the cracks after the application of the prestressing force is important as it can either confirm continued structural integrity or indicate and approximate reduced structural capacity. Structural health monitoring (SHM) can be used for this purpose. This paper researches an SHM method that can be applied to prestressed beam structures to assess the condition of pre-release cracks. The sensor network used in this method consists of parallel long-gauge fiber optic strain sensors embedded in the concrete cross-sections at various locations. The same network is used for damage detection, i.e. detection and characterization of the pre-release cracks, and for monitoring the prestress force transfer. The method is validated on a real structure, a curved continuous girder. Results from the analysis confirm the safety and integrity of the structure. The method and its application are presented in this paper.

  3. Shuttle Fuel Feedliner Cracking Investigation

    NASA Technical Reports Server (NTRS)

    Nesman, Tomas E.; Turner, Jim (Technical Monitor)

    2002-01-01

    This presentation provides an overview of material covered during 'Space Shuttle Fuel Feedliner Cracking Investigation MSFC Fluids Workshop' held November 19-21, 2002. Topics covered include: cracks on fuel feed lines of Orbiter space shuttles, fluid driven cracking analysis, liner structural modes, structural motion in a fluid, fluid borne drivers, three dimensional computational fluid dynamics models, fluid borne drivers from pumps, amplification mechanisms, flow parameter mapping, and flight engine flow map.

  4. Fatigue Crack Topography.

    DTIC Science & Technology

    1984-01-01

    continents, rihst-i- " the battlement line Nile - Lake Albert - Lake Tanganyika - Lake Malawi in Attica. Iscr~l example are all ocean ridges, for...marker band application. MARKER MARKER MARKER BANDS BANDS BANDS 6". Ist5 4..% 2M.d - W.S. 0,0 CRACK K*MAX SPECI CORD 64 8 5 q. 14 969 kg9133 0cu LR) G...AFTER HIGHEST 1-7 LOW LEVEL PEAK MARKER BLOCK BEFORE ADDED TO SEQUENCE SEVERE 1-8 FLIGHT SNO BIRD 1-9 2-40 2-5KB 2-111 2-120 LOW LEVEL 427 CYCLES

  5. Retrofitting olefin cracking plants

    SciTech Connect

    Sumner, C.; Fernandez-Baujin, J.M.

    1983-12-01

    This article discusses the retrofitting of liquid crackers which produce olefins so that gaseous feedstocks can be used. Naphtha and gas oil are the predominant design feedstocks for producing olefins. The price of gaseous feedstocks such as ethane, propane and butane have become economically more attractive than liquid feedstocks. Existing liquid crackers will be able to produce ethylene at 85% or higher capacity when cracking propane and butane feedstock with only minor changes. Topics considered include revamping for vacuum gas oil (VGO) feedstocks and revamping for liquefied petroleum gas (LPG) feedstocks.

  6. Mode II fatigue crack propagation.

    NASA Technical Reports Server (NTRS)

    Roberts, R.; Kibler, J. J.

    1971-01-01

    Fatigue crack propagation rates were obtained for 2024-T3 bare aluminum plates subjected to in-plane, mode I, extensional loads and transverse, mode II, bending loads. These results were compared to the results of Iida and Kobayashi for in-plane mode I-mode II extensional loads. The engineering significance of mode I-mode II fatigue crack growth is considered in view of the present results. A fatigue crack growth equation for handling mode I-mode II fatigue crack growth rates from existing mode I data is also discussed.

  7. Three-Dimensional Gear Crack Propagation Studies

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Sane, Ashok D.; Drago, Raymond J.; Wawrzynek, Paul A.

    1998-01-01

    Three-dimensional crack growth simulation was performed on a split-tooth gear design using boundary element modeling and linear elastic fracture mechanics. Initial cracks in the fillet of the teeth produced stress intensity factors of greater magnitude (and thus, greater crack growth rates) than those in the root or groove areas of the teeth. Crack growth simulation was performed on a case study to evaluate crack propagation paths. Tooth fracture was predicted from the crack growth simulation for an initial crack in the tooth fillet region. Tooth loads on the uncracked mesh of the split-tooth design were up to five times greater than those on the cracked mesh if equal deflections of the cracked and uncracked teeth were considered. Predicted crack shapes as well as crack propagation life are presented based on calculated stress intensity factors, mixed-mode crack propagation trajectory theories, and fatigue crack growth theories.

  8. Shear fatigue crack growth - A literature survey

    NASA Technical Reports Server (NTRS)

    Liu, H. W.

    1985-01-01

    Recent studies of shear crack growth are reviewed, emphasizing test methods and data analyses. The combined mode I and mode II elastic crack tip stress fields are considered. The development and design of the compact shear specimen are described, and the results of fatigue crack growth tests using compact shear specimens are reviewed. The fatigue crack growth tests are discussed and the results of inclined cracks in tensile panels, center cracks in plates under biaxial loading, cracked beam specimens with combined bending and shear loading, center-cracked panels and double edge-cracked plates under cyclic shear loading are examined and analyzed in detail.

  9. 21 CFR 137.190 - Cracked wheat.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Cracked wheat. 137.190 Section 137.190 Food and... Related Products § 137.190 Cracked wheat. Cracked wheat is the food prepared by so cracking or cutting... such wheat, other than moisture, remain unaltered. Cracked wheat contains not more than 15 percent...

  10. 21 CFR 137.190 - Cracked wheat.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Cracked wheat. 137.190 Section 137.190 Food and... Related Products § 137.190 Cracked wheat. Cracked wheat is the food prepared by so cracking or cutting... such wheat, other than moisture, remain unaltered. Cracked wheat contains not more than 15 percent...

  11. Effect of Crack Opening on Penetrant Crack Detectability

    NASA Technical Reports Server (NTRS)

    Weaver, Devin

    2009-01-01

    Results: From the testing we were able to determine all the cracks within the test range were detectable or better with developer. Many of the indications after development lost their linearity and gave circular indications. Our tests were performed in a laboratory and our procedure would be difficult in an industrial setting. Conclusions: The "V" did not significantly affect our ability to detect the POD cracks with fluorescent penetrant. Conduct same experiment with more cracks. The 0.025 and 0.050 POD specimens are clean and documented with the SEM. Conduct water-wash fluorescent penetrant test at EAFB. The poppet cracks are tighter than the POD specimen cracks. Flight FCV poppets: 0.01 mils (0.3 microns) Langley fatigue cracked poppets: 0.02 mils (0.5 microns) POD specimen (post 5 mils): 0.05 mils (1.4 microns) We could not detect cracks in Langley fatigue-cracked poppets with fluorescent penetrant. Investigate inability of penetrant to wet the poppet surface.

  12. Autogenic succession and deterministic recovery following disturbance in soil bacterial communities.

    PubMed

    Jurburg, Stephanie D; Nunes, Inês; Stegen, James C; Le Roux, Xavier; Priemé, Anders; Sørensen, Søren J; Salles, Joana Falcão

    2017-04-06

    The response of bacterial communities to environmental change may affect local to global nutrient cycles. However the dynamics of these communities following disturbance are poorly understood, given that they are often evaluated over macro-ecological time scales and end-point measurements. In order to understand the successional trajectory of soil bacterial communities following disturbances and the mechanisms controlling these dynamics at a scale relevant for these organisms, we subjected soil microcosms to a heat disturbance and followed the community composition of active bacteria over 50 days. The disturbance imposed a strong selective pressure that persisted for up to 10 days, after which the importance of stochastic processes increased. Three successional stages were detected: a primary response in which surviving taxa increased in abundance; a secondary response phase during which community dynamics slowed down, and a stability phase (after 29 days), during which the community tended towards its original composition. Phylogenetic turnover patterns indicated that the community experienced stronger deterministic selection during recovery. Thus, soil bacterial communities, despite their extreme diversity and functional redundancy, respond to disturbances like many macro-ecological systems and exhibit path-dependent, autogenic dynamics during secondary succession. These results highlight the role of autogenic factors and successional dynamics in microbial recovery.

  13. Biofeedback, autogenic training, and progressive relaxation in the treatment of Raynaud's disease: a comparative study.

    PubMed

    Keefe, F J; Surwit, R S; Pilon, R N

    1980-01-01

    Twenty-one female patients suffering from diagnosed idiopathic Raynaud's Disease were trained to raise digital skin temperature using either autogenic training, progressive muscle relaxation, or a combination of autogenic training and skin temperature feedback. Patients were instructed in the treatment procedures in three one-hour group sessions spaced one week apart. All patients were instructed to practice what they had learned twice a day at home. Patients kept records of the frequency of vasospastic attacks occurring over a four-week baseline period, and during the first four weeks and the ninth week of training. In addition, patients underwent four laboratory cold stress tests during which they were instructed to maintain digital temperature as the ambient temperature was slowly dropped from 26 degrees to 17 degrees C. Cold stress tests were given during week 1 of baseline and during weeks 1, 3, and 5 of training. No significant differences between the three behavioral treatment procedures were obtained. In addition, the ability of patients to maintain digital temperature during the cold stress challenge showed significant improvement from the first to the last tests. Symptomatic improvement was maintained by all patients nine weeks after the start of training. The implications of these findings for the behavioral treatment of Raynaud's Disease are discussed.

  14. Full-thickness tissue engineered skin constructed with autogenic bone marrow mesenchymal stem cells.

    PubMed

    He, LiJuan; Nan, Xue; Wang, YunFang; Guan, LiDong; Bai, CiXian; Shi, ShuangShuang; Yuan, HongFeng; Chen, Lin; Liu, Daqing; Pei, Xuetao

    2007-08-01

    To explore the feasibility of repairing clinical cutaneous deficiency, autogenic bone marrow mesenchymal stem cells (BMSCs) were isolated and differentiated into epidermal cells and fibroblasts in vitro supplemented with different inducing factors and biomaterials to construct functional tissueengineered skin. The results showed that after 72 h induction, BMSCs displayed morphologic changes such as typical epidermal cell arrangement, from spindle shape to round or oval; tonofibrils, melanosomes and keratohyaline granules were observed under a transmission electronic microscope. The differentiated cells expressed epidermal stem cell surface marker CK19 (59.66% +/- 4.2%) and epidermal cells differentiation marker CK10. In addition, the induced epidermal cells acquired the anti-radiation capacity featured by lowered apoptosis following exposure to UVB. On the other hand, the collagen microfibrils deposition was noticed under a transmission electronic microscope after differentiating into dermis fibroblasts; RT-PCR identified collagen type I mRNA expression in differentiated cells; radioimmunoassay detected the secretion of interleukin-6 (IL-6) and interleukin-8 (IL-8) (up to 115.06 pg/mL and 0.84 ng/mL, respectively). Further in vivo implanting BMSCs with scaffold material shortened skin wound repair significantly. In one word, autogenic BMSCs have the potential to differentiate into epidermal cells and fibroblasts in vitro, and show clinical feasibility acting as epidermis-like and dermis-like seed cells in skin engineering.

  15. [Use of supportive autogenic training in multiple morbidity in geriatric psychiatry patients].

    PubMed

    Kircher, T; Stetter, F; Wormstall, H

    1997-01-01

    23 multimorbid, geronto-psychiatric patients, aged 60 years or older, participated in a "supportive" course of autogenic training according to Schultz. Participating in the course an average of 7 +/- 3 weeks, 17 (76%) of the subjects were able to learn the training. In general, subjects reported a better general condition after the training sessions, measured with visual analogue scales (p < 0.001). The psychopathological status improved significantly during the time of the course (BPRS: p < 0.001; GDS: p < 0.001). No significant change was found in the cognitive state (MMSE) and the statements on the "list of complaints" ("Beschwerdenliste"). The global training success was better in the psychopathological less affected than in the more severely ill (BPRS prior r = 0.64, p = 0.001, GDS prior r = 0.46, p < 0.05). No correlation was found between training success and age, number of somatic diseases, number of medication, MMSE and the "Beschwerdenliste". Autogenic training is a useful component in psychotherapeutic and psychiatric therapy for elderly multimorbid in- and outpatients. A half-open group, two therapy sessions per week, reciting the training formulae aloud, a structured, simple setting and co-therapists proved to be worthwhile.

  16. Efficacy of aspiration and autogenous bone marrow injection in the treatment of simple bone cysts

    PubMed Central

    Abak, Alshahid A.; Bakarman, Khalid A.; Al-Jassir, Fawzi F.; Khoshhal, Khalid I.; Zamzami, Marwan M.

    2008-01-01

    Twenty eight patients with simple bone cyst that were treated by aspiration and percutaneous autogenous bone marrow injection were reviewed to evaluate the treatment outcome. There were 18 boys and ten girls. Their mean age was 10.9 ± 2.75 years. Single injection was performed for 16 patients; the rest had double or triple injections. There were no operative complications. The mean follow-up was 34.7 ± 6.87 months. The procedure succeeded in obtaining healing in 23 cysts (82%). Cysts with index of more than five and cortical thickness of less than 1 mm were significantly prone to pathological fractures and had significant poor results after treatment. Our results suggested that autogenous bone marrow injection is a safe and effective treatment method for simple bone cysts, but sometimes repeated injections are necessary. Cyst index and cortical thickness are good indicators for cyst aggressiveness and good predictors for treatment outcome. PMID:18622614

  17. Autogenic succession and deterministic recovery following disturbance in soil bacterial communities

    PubMed Central

    Jurburg, Stephanie D.; Nunes, Inês; Stegen, James C.; Le Roux, Xavier; Priemé, Anders; Sørensen, Søren J.; Salles, Joana Falcão

    2017-01-01

    The response of bacterial communities to environmental change may affect local to global nutrient cycles. However the dynamics of these communities following disturbance are poorly understood, given that they are often evaluated over macro-ecological time scales and end-point measurements. In order to understand the successional trajectory of soil bacterial communities following disturbances and the mechanisms controlling these dynamics at a scale relevant for these organisms, we subjected soil microcosms to a heat disturbance and followed the community composition of active bacteria over 50 days. The disturbance imposed a strong selective pressure that persisted for up to 10 days, after which the importance of stochastic processes increased. Three successional stages were detected: a primary response in which surviving taxa increased in abundance; a secondary response phase during which community dynamics slowed down, and a stability phase (after 29 days), during which the community tended towards its original composition. Phylogenetic turnover patterns indicated that the community experienced stronger deterministic selection during recovery. Thus, soil bacterial communities, despite their extreme diversity and functional redundancy, respond to disturbances like many macro-ecological systems and exhibit path-dependent, autogenic dynamics during secondary succession. These results highlight the role of autogenic factors and successional dynamics in microbial recovery. PMID:28383027

  18. The Volume Behavior of Autogenous Iliac Bone Grafts After Sinus Floor Elevation: A Clinical Pilot Study.

    PubMed

    Gerressen, Marcus; Riediger, Dieter; Hilgers, Ralf-Dieter; Hölzle, Frank; Noroozi, Nelson; Ghassemi, Alireza

    2015-06-01

    Iliac crest is still regarded as one of the most viable source of autogenous graft materials for extensive sinus floor elevation. Three-dimensional resorption behavior has to be taken into account in anticipation of the subsequent insertion of dental implants. We performed 3-dimensional volume measurements of the inserted bone transplants in 11 patients (6 women and 5 men; mean age = 2.3 years) who underwent bilateral sinus floor elevation with autogenous iliac crest grafts. In order to determine the respective bone graft volumes, cone-beam computerized tomography studies of the maxillary sinuses were carried out directly after the operation (T0), as well as 3 months (T1) and 6 months (T2) postoperatively. The acquired DICOM (Digital Imaging and Communications in Medicine) data sets were evaluated using suitable analysis software. We evaluated statistical significance of graft volumes changes using a linear mixed model with the grouping factors for time, age, side, and sex with a significance level of P = .05. 38.9% of the initial bone graft volume, which amounted to 4.2 cm(3), was resorbed until T1. At T2, the average volume again decreased significantly by 18.9 % to finally reach 1.8 cm(3). The results show neither age nor side dependency and apply equally to both sexes. Without functional load, iliac bone grafts feature low-volume stability in sinus-augmentation surgery. Further clinical and animal studies should be done to detect the optimal timing for implant placement.

  19. Autogenous cultured growth plate chondrocyte transplantation in the treatment of physeal injury in rabbits

    PubMed Central

    Tomaszewski, R.; Bohosiewicz, J.; Gap, A.; Bursig, H.; Wysocka, A.

    2014-01-01

    Objectives The aim of this experimental study on New Zealand’s white rabbits was to investigate the transplantation of autogenous growth plate cells in order to treat the injured growth plate. They were assessed in terms of measurements of radiological tibial varus and histological characteristics. Methods An experimental model of plate growth medial partial resection of the tibia in 14 New Zealand white rabbits was created. During this surgical procedure the plate growth cells were collected and cultured. While the second surgery was being performed, the autologous cultured growth plate cells were grafted at the right tibia, whereas the left tibia was used as a control group. Results Histological examinations showed that the grafted right tibia presented the regular shape of the plate growth with hypertrophic maturation, chondrocyte columniation and endochondral calcification. Radiological study shows that the mean tibial deformity at the left angle was 20.29° (6.25 to 33) and 7.21° (5 to 10) in the right angle. Conclusion This study has demonstrated that grafting of autogenous cultured growth plate cells into a defect of the medial aspect of the proximal tibial physis can prevent bone bridge formation, growth arrest and the development of varus deformity. Cite this article: Bone Joint Res 2014;3:310–16 PMID:25376625

  20. Formation of a chronic pain syndrome due to mesh shrinkage after laparoscopic intraperitoneal onlay mesh (IPOM).

    PubMed

    Klein, Fritz; Ospina, Carlos; Rudolph, Birgit; Wüstefeld, Joost; Denecke, Timm; Neuhaus, Peter; Schmidt, Sven-Christian

    2012-10-01

    The case of a 58-year-old male patient who developed a chronic pain syndrome after laparoscopic intraperitoneal onlay mesh for treatment of a large symptomatic umbilical hernia combined with rectus diastasis is reported. Twelve months after an uncomplicated initial surgery, the patient presented with progressive signs of a foreign body sensation and pain in the anterior abdominal wall. Computed tomography examination revealed no pathologic findings but a marked shrinkage of the mesh implant. Because of further progressive symptoms, explorative laparotomy was performed. Mesh shrinkage and adhesions with a surrounding chronic tissue reaction were found as the cause of the pain syndrome. This case demonstrates a case of a chronic pain syndrome due to mesh shrinkage 12 months after initial ventral hernia repair. Mesh shrinkage should therefore be taken into consideration in patients with progressive pain chronic syndromes after laparoscopic ventral hernia repair.

  1. Measurement of composite shrinkage using a fibre optic Bragg grating sensor.

    PubMed

    Milczewski, M S; Silva, J C C; Paterno, A S; Kuller, F; Kalinowski, H J

    2007-01-01

    Fibre Bragg grating is used to determine resin-based composite shrinkage. Two composite resins (Freedom from SDI and Z100 from 3M) were tested to determine the polymerization contraction behaviour. Each sample of resin was prepared with an embedded fibre Bragg grating. A LED activation unit with wavelength from 430 nm to 470 nm (Dabi Atlante) was used for resin polymerization. The wavelength position of the peak in the optical reflection spectra of the sensor was measured. The wavelength shift was related to the shrinkage deformation of the samples. Temperature and strain evolution during the curing phase of the material was monitored. The shrinkage in the longitudinal direction was 0.15 +/- 0.02% for resin Z100 (3M) and 0.06+/-0.01% for Freedom (SDI); two-thirds of shrinkage occurred after the first 50 s of illumination.

  2. Numerical Simulation on Open Wellbore Shrinkage and Casing Equivalent Stress in Bedded Salt Rock Stratum

    PubMed Central

    Liu, Jianjun

    2013-01-01

    Most salt rock has interbed of mudstone in China. Owing to the enormous difference of mechanical properties between the mudstone interbed and salt rock, the stress-strain and creep behaviors of salt rock are significantly influenced by neighboring mudstone interbed. In order to identify the rules of wellbore shrinkage and casings equivalent stress in bedded salt rock stratum, three-dimensional finite difference models were established. The effects of thickness and elasticity modulus of mudstone interbed on the open wellbore shrinkage and equivalent stress of casing after cementing operation were studied, respectively. The results indicate that the shrinkage of open wellbore and equivalent stress of casings decreases with the increase of mudstone interbed thickness. The increasing of elasticity modulus will reduce the shrinkage of open wellbore and casing equivalent stress. Research results can provide the scientific basis for the design of mud density and casing strength. PMID:24198726

  3. The effects of epoxy shrinkage on the Advanced X-ray Astrophysics Facility Technology Mirror Assembly

    NASA Technical Reports Server (NTRS)

    Cohen, L. M.

    1984-01-01

    A method is shown analytically which reduces the effects of epoxy shrinkage for an ultra-high precision X-ray telescope to within the system error budget. The three-dimensional shrinkage effects are discussed with reference to this telescope. The results of the analysis point to the use of an interrupted rather than continuous bond line as the best solution. Discussion of the finite element modelling techniques is included.

  4. Effect of Shrinkage on Primary Dendrite Arm Spacing during Binary Al-Si Alloy Solidification

    NASA Astrophysics Data System (ADS)

    Wang, Hongda; Hamed, Mohamed S.; Shankar, Sumanth

    2011-08-01

    Upward and downward directional solidification of hypoeutectic Al-Si alloys were numerically simulated inside a cylindrical container. Undercooling of the liquidus temperature prior to the solidification event was introduced in the numerical model. The finite-volume method was used to solve the energy, concentration, momentum, and continuity equations. Temperature and liquid concentrations inside the mushy zone were coupled with local equilibrium assumptions. An energy equation was applied to determine the liquid fraction inside the mushy zone while considering the temperature undercooling at the solidifying dendrite/liquid interface. Momentum and continuity equations were coupled by the SIMPLE algorithm. Flow velocity distribution at various times, G, R, λ 1, and solidification time at mushy zone/liquid interface during solidification were predicted. The effect of shrinkage during solidification on these solidification parameters was quantified. Transient temperature distribution, solidification time for the mushy zone/liquid interface, and λ 1 were validated by laboratory experiments. It was found that better agreement could be achieved when the fluid flow due to solidification shrinkage was considered. Considering shrinkage in upward solidification was found to only have a marginal effect on solidification parameters, such as G, R, and λ 1; whereas, in the downward solidification, fluid flow due to shrinkage had a significant effect on these solidification parameters. Considering shrinkage during downward solidification resulted in a smaller R, stronger fluid flow, and increased solidification time at the mushy zone/liquid interface. Further, the flow pattern was significantly altered when solidification shrinkage was considered in the simulation. The effect of shrinkage on G and λ 1 strongly depended on the instantaneous location of the mushy zone/liquid interface in the computational domain. The numerical results could be validated by experimental data

  5. The effect of mucosal cuff shrinkage around dental implants during healing abutment replacement.

    PubMed

    Nissan, J; Zenziper, E; Rosner, O; Kolerman, R; Chaushu, L; Chaushu, G

    2015-10-01

    Soft tissue shrinkage during the course of restoring dental implants may result in biological and prosthodontic difficulties. This study was conducted to measure the continuous shrinkage of the mucosal cuff around dental implants following the removal of the healing abutment up to 60 s. Individuals treated with implant-supported fixed partial dentures were included. Implant data--location, type, length, diameter and healing abutments' dimensions--were recorded. Mucosal cuff shrinkage, following removal of the healing abutments, was measured in bucco-lingual direction at four time points--immediately after 20, 40 and 60 s. anova was used to for statistical analysis. Eighty-seven patients (49 women and 38 men) with a total of 311 implants were evaluated (120 maxilla; 191 mandible; 291 posterior segments; 20 anterior segments). Two-hundred and five (66%) implants displayed thick and 106 (34%) thin gingival biotype. Time was the sole statistically significant parameter affecting mucosal cuff shrinkage around dental implants (P < 0.001). From time 0 to 20, 40 and 60 s, the mean diameter changed from 4.1 to 4.07, 3.4 and 2.81 mm, respectively. The shrinkage was 1%, 17% and 31%, respectively. The gingival biotype had no statistically significant influence on mucosal cuff shrinkage (P = 0.672). Time required replacing a healing abutment with a prosthetic element should be minimised (up to 20/40 s), to avoid pain, discomfort and misfit.

  6. Transient brain shrinkage in infantile spasms after ACTH treatment. Report of two cases.

    PubMed

    Maekawa, K; Ohta, H; Tamai, I

    1980-02-01

    This is the report of two cases of infantile spasms, manifesting transient brain shrinkage in computerized tomography (CT) after ACTH treatment. ACTH was given for 8 weeks to a 8-months-old Japanese girl with infantile spasms. First CT performed at 2 weeks after the final ACTH injection, displayed moderate brain shrinkage. Second CT at 4 months showed marked diminution of the shrinkage. ACTH was also given for 8 weeks to a 14 months old Japanese boy with infantile spasms. First CT, just before ACTH treatment, showed mild cortical atrophy, the second at 7 days after the final ACTH injection revealed marked brain shrinkage and moderate ventricular dilatation, and the third at 2 months, disclosed mild improvement of the shrinkage. ACTH or corticoateroid has widespread effects on the developing nervous system. In animal experiments, ACTH or steroids interfere with brain growth of young rats. CT findings of transient brain shrinkage in a child with infantile spasms might suggest that intensive treatment with ACTH or steroids in infancy interferes with brain growth as seen in the results of animal experiments.

  7. Microcomputed Tomography Evaluation of Polymerization Shrinkage of Class I Flowable Resin Composite Restorations.

    PubMed

    Sampaio, C S; Chiu, K-J; Farrokhmanesh, E; Janal, M; Puppin-Rontani, R M; Giannini, M; Bonfante, E A; Coelho, P G; Hirata, R

    The present study aimed to characterize the pattern and volume of polymerization shrinkage of flowable resin composites, including one conventional, two bulk fill, and one self-adhesive. Standardized class I preparations (2.5 mm depth × 4 mm length × 4 mm wide) were performed in 24 caries-free human third molars that were randomly divided in four groups, according to the resin composite and adhesive system used: group 1 = Permaflo + Peak Universal Bond (PP); group 2 = Filtek Bulk Fill + Scotchbond Universal (FS); group 3 = Surefil SDR + XP Bond (SX); and group 4 = Vertise flow self-adhering (VE) (n=6). Each tooth was scanned three times using a microcomputed tomography (μCT) apparatus. The first scan was done after the cavity preparation, the second after cavity filling with the flowable resin composite before curing, and the third after it was cured. The μCT images were imported into three-dimensional rendering software, and volumetric polymerization shrinkage percentage was calculated for each sample. Data were submitted to one-way analysis of variance and post hoc comparisons. No significant difference was observed among PP, FS, and VE. SX bulk fill resin composite presented the lowest values of volumetric shrinkage. Shrinkage was mostly observed along the occlusal surface and part of the pulpal floor. In conclusion, polymerization shrinkage outcomes in a 2.5-mm deep class I cavity were material dependent, although most materials did not differ. The location of shrinkage was mainly at the occlusal surface.

  8. Drying shrinkage of fibre-reinforced lightweight aggregate concrete containing fly ash

    SciTech Connect

    Kayali, O.; Haque, M.N.; Zhu, B.

    1999-11-01

    Lightweight aggregate concretes containing fly ash with a compressive strength between 61 to 67 NPa were produced. The lightweight aggregate used was sintered fly ash. The concretes were reinforced with either polypropylene or steel fibres. The fibres did not affect the compressive strength, but did increase the tensile strength of these concretes. The modulus of elasticity of all the lightweight concretes tested was about 21 GPa, compared to 35 GPa for the normal-weight concrete. Fibre reinforcement did not affect the value of the elastic modulus. This type of lightweight concrete, containing fly ash as 23% of the total cementitious content, resulted in long-term shrinkage that is nearly twice as large as normal-weight concrete of somewhat similar strength. Polypropylene fibre reinforcement did not reduce drying shrinkage, while steel fibres did. Early shrinkage behavior of this type of lightweight concrete was similar to normal-weight concrete. However, the rate of shrinkage of the lightweight concrete remained constant until nearly 100 days of drying. This is different from normal-weight concrete that showed appreciably after 56 days. Shrinkage of normal-weight concrete stabilized after 400 days, which shrinkage of lightweight concrete did not appear to stabilize after a similar period of continuous drying.

  9. Replica-Based Crack Inspection

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Willard, Scott A.; Smith, Stephen W.; Piascik, Robert S.

    2008-01-01

    Surface replication has been proposed as a method for crack detection in space shuttle main engine flowliner slots. The results of a feasibility study show that examination of surface replicas with a scanning electron microscope can result in the detection of cracks as small as 0.005 inch, and surface flaws as small as 0.001 inch, for the flowliner material.

  10. Experiences on IGSCC crack manufacturing

    SciTech Connect

    Veron, P.

    1997-02-01

    The author presents his experience in manufacturing IGSCC realistic defects, mainly in INCONEL 600 MA Steam Generator Tubes. From that experience he extracts some knowledge about this cracking (influence of chemistry in the environment, stress state, crack growth rate, and occurrence in laboratory condition of break before leak).

  11. A Single Session of Autogenic Training Increases Acute Subjective and Physiological Sexual Arousal in Sexually Functional Women.

    PubMed

    Stanton, Amelia; Meston, Cindy

    2016-07-11

    Heart rate variability (HRV) has recently been associated with female sexual function (Stanton, Lorenz, Pulverman, & Meston, 2015). Below-average HRV was identified as a possible risk factor for sexual arousal dysfunction and overall sexual dysfunction in women. Based on this newly established relationship between HRV and female sexual function, the present study examined the effect of autogenic training to increase HRV on acute physiological and subjective sexual arousal in women. Specifically, vaginal pulse amplitude (VPA), an index of genital sexual arousal, and subjective sexual arousal were assessed in 33 sexually functional women, aged 18 to 27, before and after a short session of autogenic training. Autogenic training, a relaxation technique that restores the balance between the activity of the sympathetic and the parasympathetic branches of the autonomic nervous system, has been shown to significantly increase HRV (Miu, Heilman, & Miclea, 2009). After autogenic training, significant increases in both VPA (p <.05) and subjective sexual arousal (p <.005) were observed. Moreover, change in HRV from pre- to postmanipulation significantly moderated changes in subjective sexual arousal (p <.05) when it was measured continuously during the presentation of the erotic stimulus. This cost-effective, easy-to-administer behavioral intervention may have important implications for increasing sexual arousal in women.

  12. Effect of biofeedback-assisted autogenic training on headache activity and mood states in Korean female migraine patients.

    PubMed

    Kang, Eun-Ho; Park, Joo-Eon; Chung, Chin-Sang; Yu, Bum-Hee

    2009-10-01

    Biofeedback with or without combined autogenic training is known to be effective for the treatment of migraine. This study aimed to examine the effect of biofeedback treatment on headache activity, anxiety, and depression in Korean female patients with migraine headache. Patients were randomized into the treatment group (n=17) and monitoring group (n=15). Mood states including anxiety and depression, and psychophysiological variables such as mean skin temperature of the patients were compared with those of the normal controls (n=21). We found greater treatment response rate (defined as > or =50% reduction in headache index) in patients with biofeedback-assisted autogenic training than in monitoring group. The scores on the anxiety and depression scales in the patients receiving biofeedback-assisted autogenic training decreased after the biofeedback treatment. Moreover, the decrease in their anxiety levels was significantly related to the treatment outcome. This result suggests that the biofeedback-assisted autogenic training is effective for the treatment of migraine and its therapeutic effect is closely related to the improvement of the anxiety level.

  13. The application of autogenic training in counseling center for mother and child in order to promote breastfeeding.

    PubMed

    Vidas, Mercedes; Folnegović-Smalc, Vera; Catipović, Marija; Kisić, Marko

    2011-09-01

    The aim of this study was to investigate whether mothers with newborn children, the usage of autogenic training with advice on breastfeeding effect on: the decision and the duration of breastfeeding, increase maternal confidence and support. It was assumed that the above result in a higher percentage of mothers who exclusively breastfed baby during the first six months of child's life. The survey was conducted in the Association "For a healthy and happy childhood"-Counseling center for mother and child, in Bjelovar in 2010. The Counseling center was attended by 100 nursing mothers with children aged up to two months. They randomly went to the study or control group. Mothers of both groups were advised to successful breastfeeding. Study group has practiced autogenic training until the child's age of six months. In parallel, by using psychotherapeutic interview and specific questionnaires we collected data on the somatic, psychological and social situation of the mother, discovered mother's mental changes (anxiety, depression) that were treated. The results at the end of the study confirm the initial expected benefits from the application of autogenic training. Mothers of the study group were significantly more emotionally balanced with a higher self-esteem. Autogenous training with the advices for successful breastfeeding conducted in this counseling center contributed in significantly higher rate of breastfeeding children up to six months of life, improved mental and physical health of mother and child and their peculiar relationship.

  14. Comparison of autogenic and allogenic bone marrow derived mesenchymal stem cells for repair of segmental bone defects in rabbits.

    PubMed

    Udehiya, Rahul Kumar; Amarpal; Aithal, H P; Kinjavdekar, P; Pawde, A M; Singh, Rajendra; Taru Sharma, G

    2013-06-01

    Autogenic and allogenic bone marrow derived mesenchymal stem cells (BM-MSCs) were compared for repair of bone gap defect in rabbits. BM-MSCs were isolated from bone marrow aspirates and cultured in vitro for allogenic and autogenic transplantation. A 5mm segmental defect was created in mid-diaphysis of the radius bone. The defect was filled with hydroxyapatite alone, hydroxyapatite with autogeneic BM-MSCs and hydroxyapatite with allogenic BM-MSCs in groups A, B and C, respectively. On an average 3.45×10(6) cells were implanted at each defect site. Complete bridging of bone gap with newly formed bone was faster in both treatment groups as compared to control group. Histologically, increased osteogenesis, early and better reorganization of cancellous bone and more bone marrow formation were discernible in treatment groups as compared to control group. It was concluded that in vitro culture expanded allogenic and autogenic BM-MSCs induce similar, but faster and better healing as compared to control.

  15. Reconstruction of alveolar bone defect with autogenous bone particles and osseointegrated implants: Histologic analysis and 10 years monitoring

    PubMed Central

    de Carvalho, Paulo Sérgio Perri; de Carvalho, Mariliza Comar Astolphi; Ponzoni, Daniela

    2015-01-01

    Maintaining the volume of the alveolar process after extraction can be achieved by immediate implant placement and guided bone regeneration, with or without the use of biomaterials. The authors present a case report with a 10 years follow-up, rehabilitation using osseointegrated implants in the extraction area and maintenance of the volume of the alveolar process with autogenous cortical bone shavings. PMID:26389054

  16. Hydrocarbon cracking and reforming process

    SciTech Connect

    Le, Q.N.; Schipper, P.H.; Owen, H.

    1992-03-31

    This patent describes a process for upgrading paraffinic naphtha to high octane fuel. It comprises: contacting a fresh naphtha feedstock stream containing a major amount of C{sub 7+} alkanes and naphthenes with medium pore acid cracking catalyst under low pressure selective cracking conditions effective to produce 4-C5 isoalkene and C4-C5 isoalkane, the cracking catalyst being substantially free of hydrogenation-dehydrogenation metal components and having an acid cracking activity less than 15; separating cracking effluent to obtain an olefinic fraction rich in C4-C5 isoalkene and a C6+ fraction; etherifying the C4-C5 isoalkene fraction by catalytic reaction with lower alkanol to produce tertiary-alkyl ether product; and reforming the C6+ fraction to provide high octane gasoline components.

  17. High speed thin plate fatigue crack monitor

    NASA Technical Reports Server (NTRS)

    Wincheski, Buzz A. (Inventor); Heyman, Joseph S. (Inventor); Namkung, Min (Inventor); Fulton, James P. (Inventor)

    1996-01-01

    A device and method are provided which non-destructively detect crack length and crack geometry in thin metallic plates. A non-contacting vibration apparatus produces resonant vibrations without introducing extraneous noise. Resulting resonant vibration shifts in cracked plates are correlated to known crack length in plates with similar resonant vibration shifts. In addition, acoustic emissions of cracks at resonance frequencies are correlated to acoustic emissions from known crack geometries.

  18. Comparing alveolar bone regeneration using Bio-Oss and autogenous bone grafts in humans: a systematic review and meta-analysis

    PubMed Central

    Akbarzadeh Baghban, Alireza; Dehghani, Azam; Ghanavati, Farzin; Zayeri, Farid; Ghanavati, Farzam

    2009-01-01

    INTRODUCTION: Bone regeneration grafts (BRG) are widely used in the treatment of osseous defects and oral surgery. The various techniques and associated success rates of bone augmentation require evaluation by systematic review and meta-analysis of eligible studies. The aim of this systematic review was to compare alveolar bone regeneration in humans using Bio-Oss and autogenous bone graft. MATERIALS AND METHODS: The computerized bibliographical databases including Pubmed, Google, ScienceDirect and Cochrane were searched for randomized and cohort studies in which autogenous grafts were compared to Bio-Oss in the treatment of periodontal defects. The inclusion criteria were human studies in English that were published 1998-2009. Exclusion criteria included non randomized observation and cohort studies, papers which provided summary statistics without the variance estimates, and studies that did not use BRG intervention alone, were excluded. The screening of eligible studies, assessment of the methodological quality of the trials and data extraction were collected by two observers independently. For comparing autogenous grafts used alone against Bio-Oss used alone 5 situations were investigated. Thirteen studies were included in the review which compared autogenous against Bio-Oss, autogenous combined with guided tissue regeneration (GTR) against GTR, Bio-Oss combined with GTR versus GTR, autogenous alone versus Open Flap Debridement (OFD), Bio-Oss versus OFD. In meta-analysis, changes in bone level (bone fill) was used as the measure. Data were analyzed using Bayesian meta-analysis by WinBUGS and Boa software. RESULTS: Only one comparison demonstrated that the difference in bone augmentation between Bio-Oss and OFD was statistically significant. CONCLUSION: There is insufficient evidence to show that Bio-Oss is superior to autogenous grafts in bone augmentation techniques however autogenous bone involves donor site surgery and thus donor site morbidity, so we can

  19. Effects of low-level laser therapy on autogenous bone graft stabilized with a new heterologous fibrin sealant.

    PubMed

    de Oliveira Gonçalves, Jéssica Barbosa; Buchaim, Daniela Vieira; de Souza Bueno, Cleuber Rodrigo; Pomini, Karina Torres; Barraviera, Benedito; Júnior, Rui Seabra Ferreira; Andreo, Jesus Carlos; de Castro Rodrigues, Antonio; Cestari, Tania Mary; Buchaim, Rogério Leone

    2016-09-01

    Autogenous bone grafts are used to repair bone defects, and the stabilization is needed for bone regeneration. Laser photobiomodulation is a modality of treatment in clinical practice for tissue regeneration, and it has therapeutic effects as an anti-inflammatory, analgesic and modulating cellular activity. The aim of the present study was to evaluate the effects of low-level laser therapy (LLLT) on an autogenous bone graft integration process stabilized with a new heterologous fibrin sealant. Forty rats were divided into two groups: Autogenous Fibrin Graft (AFG, n=20), in which a 5mm dome osteotomy was conducted in the right parietal bone and the graft was adhered to the left side using fibrin sealant; and Autogenous Fibrin Graft Laser (AFGL, n=20), which was subjected to the same procedures as AFG with the addition of LLLT. The treatment was performed immediately following surgery and then three times a week until euthanasia, using an 830nm laser (30mW, 6J/cm(2), 0.116cm(2), 258.6mW/cm(2), 2.9J). Five animals from each group were euthanized at 10, 20, 30 and 40days postoperative, and the samples were submitted to histomorphological and histomorphometric analysis. Partial bone regeneration occurred, with new bone tissue integrating the graft to the recipient bed and small areas of connective tissue. Comparative analysis of the groups at the same intervals revealed minor interfaces in group AFGL, with statistically significant differences (p<0.05) at all of the analyzed intervals (10days p=0.0087, 20days p=0.0012, 30days p<0.0001, 40days p=0.0142). In conclusion, low-level laser therapy stimulated bone regeneration and accelerated the process of integration of autogenous bone grafts.

  20. Captures, Cutoffs, and Autogenic Drainage Basin Reorganization from Bedrock River Meandering in the Oregon Coast Range

    NASA Astrophysics Data System (ADS)

    Johnson, K. N.; Finnegan, N. J.

    2015-12-01

    Meandering bedrock channels in the Oregon Coast Range (OCR), USA, have lateral migration rates far in excess of vertical incision rates. Consequently, the sweeping of trunk streams through this landscape can locally exert a much stronger influence on tributary channel long profiles than far-field tectonic forcing of base-level. Here, we use LiDAR-data to explore the influence of lateral channel mobility on the evolution of tributaries to the Smith River, in the OCR. We focus on two processes that dramatically and instantaneously change tributary long profiles: 1) Capture of tributaries by growing meander bends, and 2) Meander bend neck cutoffs on the main-stem that leave tributaries disconnected from base-level lowering. We focus on these two types of events because they provide clear examples of autogenic drivers of landscape disequilibrium at the sub-watershed scale in a landscape that is commonly argued to reflect steady tectonic forcing of base-level. We show that tributary streams are significantly more likely to flow into the leading edge of meander bends, testifying to the repeated capture of tributaries by growing bends. Examples of eminent captures by migrating bends, and examples with large knick points along recently captured tributaries suggest that the autogenic capture of tributaries by growing bends is a fundamental cause of transience in tributary channels in this landscape. To demonstrate the influence of the process of meander bend neck cutoff on tributary long profile evolution, we compare the long profiles of 34 tributaries that were hung above the main-stem of the Smith River following neck cutoff events. These stagnated tributary channels typically exhibit large convexities that record ongoing lowering of the trunk stream. Measured heights of these hanging tributaries implies that the timescale of adjustment for tributaries following cutoff events is ~ 105-106 years. The timescale of adjustment of tributary channels following meander cutoff

  1. Spacing of crack patterns driven by steady-state cooling or drying and influenced by a solidification boundary

    NASA Astrophysics Data System (ADS)

    Hofmann, Martin; Bahr, Hans-Achim; Weiss, Hans-Jürgen; Bahr, Ute; Balke, Herbert

    2011-03-01

    Regular columnar joints that originate from networklike crack patterns can be observed in basalt and, on a much smaller scale, in dried starch slurry. Here, the basalt columns are idealized by a periodic array of parallel cracks driven by steady-state cooling. By means of a bifurcation analysis, the minimal possible crack spacing for sustained propagation of the crack array is calculated. It can be shown qualitatively that the minimal possible crack spacing for sustained propagation increases with decreasing velocity. This is confirmed by numerical calculations. The latent heat released at the solidification front is taken into account in the thermomechanical linear-elastic model of propagating shrinkage. Our calculations show that the solidification front is positioned not far ahead of the crack tips, which influences the result considerably. The results agree reasonably well with new measured data of basalt columns. By use of the analogy between contraction due to cooling and that due to drying the model is applied for columns in dried cornstarch, too, showing good agreement with recent experimental data.

  2. Leaf Shrinkage with Dehydration: Coordination with Hydraulic Vulnerability and Drought Tolerance1[C][W][OPEN

    PubMed Central

    Scoffoni, Christine; Vuong, Christine; Diep, Steven; Cochard, Hervé; Sack, Lawren

    2014-01-01

    Leaf shrinkage with dehydration has attracted attention for over 100 years, especially as it becomes visibly extreme during drought. However, little has been known of its correlation with physiology. Computer simulations of the leaf hydraulic system showed that a reduction of hydraulic conductance of the mesophyll pathways outside the xylem would cause a strong decline of leaf hydraulic conductance (Kleaf). For 14 diverse species, we tested the hypothesis that shrinkage during dehydration (i.e. in whole leaf, cell and airspace thickness, and leaf area) is associated with reduction in Kleaf at declining leaf water potential (Ψleaf). We tested hypotheses for the linkage of leaf shrinkage with structural and physiological water relations parameters, including modulus of elasticity, osmotic pressure at full turgor, turgor loss point (TLP), and cuticular conductance. Species originating from moist habitats showed substantial shrinkage during dehydration before reaching TLP, in contrast with species originating from dry habitats. Across species, the decline of Kleaf with mild dehydration (i.e. the initial slope of the Kleaf versus Ψleaf curve) correlated with the decline of leaf thickness (the slope of the leaf thickness versus Ψleaf curve), as expected based on predictions from computer simulations. Leaf thickness shrinkage before TLP correlated across species with lower modulus of elasticity and with less negative osmotic pressure at full turgor, as did leaf area shrinkage between full turgor and oven desiccation. These findings point to a role for leaf shrinkage in hydraulic decline during mild dehydration, with potential impacts on drought adaptation for cells and leaves, influencing plant ecological distributions. PMID:24306532

  3. Formation of shrinkage porosity during solidification of steel: Numerical simulation and experimental validation

    NASA Astrophysics Data System (ADS)

    Riedler, M.; Michelic, S.; Bernhard, C.

    2016-07-01

    The phase transformations in solidification of steel are accompanied by shrinkage and sudden changes in the solubility of alloying elements, resulting in negative side effects as micro- and macrosegregation and the formation of gas and shrinkage porosities. This paper deals with the numerical and experimental simulation of the formation of shrinkage porosity during the solidification of steel. First the physical basics for the mechanism of shrinkage pore formation will be discussed. The main reason for this type of porosity is the restraint of fluid flow in the mushy zone which leads to a pressure drop. The pressure decreases from the dendrite tip to the root. When the pressure falls below a critical value, a pore can form. The second part of the paper deals with different approaches for the prediction of the formation of shrinkage porosity. The most common one according to these models is the usage of a simple criterion function, like the Niyama criterion. For the computation of the porosity criterion the thermal gradient, cooling rate and solidification rate must be known, easily to determine from numerical simulation. More complex simulation tools like ProCAST include higher sophisticated models, which allow further calculations of the shrinkage cavity. Finally, the different approaches will be applied to a benchmark laboratory experiment. The presented results deal with an ingot casting experiment under variation of taper. The dominant influence of mould taper on the formation of shrinkage porosities can both be demonstrated by the lab experiment as well as numerical simulations. These results serve for the optimization of all ingot layouts for lab castings at the Chair of Ferrous Metallurgy.

  4. Temperature-dependent biphasic shrinkage of lipid-coated bubbles in ultrasound.

    PubMed

    Cox, Debra J; Thomas, James L

    2013-04-09

    Lipid-coated microbubbles and emulsions are of interest as possible ultrasound-mediated drug delivery vehicles and for their interesting behaviors and fundamental properties. We and others have noted that bubbles coated with the long chain saturated phospholipid distearoylphosphatidylcholine (DSPC) rapidly shrink to a quasistable size when repeatedly insonated with short ultrasound pulses; such stability may adversely affect the bubble's subsequent ability to deliver its pharmacological cargo. Bubbles coated with the unsaturated lipid dioleoylphosphatidylcholine (DOPC) did not show stability but did undergo an abrupt change from rapid initial shrinkage to a slow persistent shrinkage, leading ultimately to dissolution or dispersion. As DOPC and DSPC differ not only in chain saturation but also phase behavior, we performed additional studies using dimyristoyl PC (DMPC) as a coat lipid and controlled the solution temperature to study bubble behavior on exposure to repeated ultrasound pulses for the same coat, in both fluid and gel phases. We find, first, that essentially all bubbles show an initially rapid shrinkage, in which gas loss exceeds the limit imposed by gas diffusion into the surrounding medium; this rapid shrinkage may be evidence of nanoscopic bubble fragmentation. Second, upon reaching a fraction of their initial size, bubbles begin a slower shrinkage with a shrinkage rate that depends on the resting phase state of the coat lipid: fluid DMPC monolayers give a more rapid shrinkage than gel phase. DOPC-coated bubbles showed no temperature-dependent responses in the same temperature range. The results are especially interesting in that bubble compression during the pulse is likely to adiabatically heat the bubble and fluidize the coat, regardless of its initial phase state; thus, some structural feature of the resting coat, such as defect lines in the gel phase, may be important in the subsequent response to the ~3 μs ultrasound pulse.

  5. Leaf shrinkage with dehydration: coordination with hydraulic vulnerability and drought tolerance.

    PubMed

    Scoffoni, Christine; Vuong, Christine; Diep, Steven; Cochard, Hervé; Sack, Lawren

    2014-04-01

    Leaf shrinkage with dehydration has attracted attention for over 100 years, especially as it becomes visibly extreme during drought. However, little has been known of its correlation with physiology. Computer simulations of the leaf hydraulic system showed that a reduction of hydraulic conductance of the mesophyll pathways outside the xylem would cause a strong decline of leaf hydraulic conductance (K(leaf)). For 14 diverse species, we tested the hypothesis that shrinkage during dehydration (i.e. in whole leaf, cell and airspace thickness, and leaf area) is associated with reduction in K(leaf) at declining leaf water potential (Ψ(leaf)). We tested hypotheses for the linkage of leaf shrinkage with structural and physiological water relations parameters, including modulus of elasticity, osmotic pressure at full turgor, turgor loss point (TLP), and cuticular conductance. Species originating from moist habitats showed substantial shrinkage during dehydration before reaching TLP, in contrast with species originating from dry habitats. Across species, the decline of K(leaf) with mild dehydration (i.e. the initial slope of the K(leaf) versus Ψ(leaf) curve) correlated with the decline of leaf thickness (the slope of the leaf thickness versus Ψ(leaf) curve), as expected based on predictions from computer simulations. Leaf thickness shrinkage before TLP correlated across species with lower modulus of elasticity and with less negative osmotic pressure at full turgor, as did leaf area shrinkage between full turgor and oven desiccation. These findings point to a role for leaf shrinkage in hydraulic decline during mild dehydration, with potential impacts on drought adaptation for cells and leaves, influencing plant ecological distributions.

  6. Analysis of Crack Arrest Toughness.

    DTIC Science & Technology

    1988-01-15

    vload(m) vp tn(m) Vertical Source Load (kN) on wedge HY80 Finite Element 0.0122 0.0099 3.81x10 -4 144 Steel Calculations Experiment 0.0122 --- 3.74x10-4...curve, are bona fide measures of the fracture arrest capability of tough ductile steels . The second is that the J-values represent the crack driving...fibrous mode of crack extension. (b) A new test method for studying fast fracture and arrest in tough steels . (c) Measurements of fast fracture and crack

  7. Ductility dip cracking susceptibility of Inconel Filler Metal 52 and Inconel Alloy 690

    SciTech Connect

    Kikel, J.M.; Parker, D.M.

    1998-06-01

    Alloy 690 and Filler Metal 52 have become the materials of choice for commercial nuclear steam generator applications in recent years. Filler Metal 52 exhibits improved resistance to weld solidification and weld-metal liquation cracking as compared to other nickel-based filler metals. However, recently published work indicates that Filler Metal 52 is susceptible to ductility dip cracking (DDC) in highly restrained applications. Susceptibility to fusion zone DDC was evaluated using the transverse varestraint test method, while heat affected zone (HAZ) DDC susceptibility was evaluated using a newly developed spot-on-spot varestraint test method. Alloy 690 and Filler Metal 52 cracking susceptibility was compared to the DDC susceptibility of Alloy 600, Filler Metal 52, and Filler Metal 625. In addition, the effect of grain size and orientation on cracking susceptibility was also included in this study. Alloy 690, Filler Metal 82, Filler Metal 52, and Filler Metal 625 were found more susceptible to fusion zone DDC than Alloy 600. Filler Metal 52 and Alloy 690 were found more susceptible to HAZ DDC when compared to wrought Alloy 600, Filler Metal 82 and Filler Metal 625. Filler Metal 52 exhibited the greatest susceptibility to HAZ DDC of all the weld metals evaluated. The base materials were found much more resistant to HAZ DDC in the wrought condition than when autogenously welded. A smaller grain size was found to offer greater resistance to DDC. For weld metal where grain size is difficult to control, a change in grain orientation was found to improve resistance to DDC.

  8. A computational algorithm for crack determination: The multiple crack case

    NASA Technical Reports Server (NTRS)

    Bryan, Kurt; Vogelius, Michael

    1992-01-01

    An algorithm for recovering a collection of linear cracks in a homogeneous electrical conductor from boundary measurements of voltages induced by specified current fluxes is developed. The technique is a variation of Newton's method and is based on taking weighted averages of the boundary data. The method also adaptively changes the applied current flux at each iteration to maintain maximum sensitivity to the estimated locations of the cracks.

  9. Stress intensity and crack displacement for small edge cracks

    NASA Technical Reports Server (NTRS)

    Orange, Thomas W.

    1988-01-01

    The weight function method was used to derive stress intensity factors and crack mouth displacement coefficients for small edge cracks (less than 20 percent of the specimen width) in common fracture specimen configurations. Contact stresses due to point application of loads were found to be small but significant for three-point bending and insignificant for four-point bending. The results are compared with available equations and numerical solutions from the literature and with unpublished boundary collocation results.

  10. Autogenic feedback training experiment: A preventative method for space motion sickness

    NASA Technical Reports Server (NTRS)

    Cowings, Patricia S.

    1993-01-01

    Space motion sickness is a disorder which produces symptoms similar to those of motion sickness on Earth. This syndrome has affected approximately 50 percent of all astronauts and cosmonauts exposed to microgravity in space, but it differs from what is commonly known as motion sickness in a number of critical ways. There is currently no ground-based method for predicting susceptibility to motion sickness in space. Antimotion sickness drugs have had limited success in preventing or counteracting symptoms in space, and frequently caused debilitating side effects. The objectives were: (1) to evaluate the effectiveness of Autogenic-Feedback Training as a countermeasure for space motion sickness; (2) to compare physiological data and in-flight symptom reports to ground-based motion sickness data; and (3) to predict susceptibility to space motion sickness based on pre-flight data of each treatment group crew member.

  11. Contiguous autogenous transplant--nineteen years' clinical and radiographic follow-up: a case report.

    PubMed

    Sperling, I; Kozlovsky, A; Tal, H

    1994-08-01

    Contiguous autogenous transplant, also known as the bone-swaging procedure, is a technique aimed at regenerating lost periodontium. Clinical healing of bony defects after bone swaging has been satisfactory, but the relationship and mode of attachment between the bone graft and the root surface have not been fully investigated. A 19-year clinical and radiographic follow-up of a bony defect treated with the bone-swaging technique is presented. A significant coronal increase in bone height and a gain in clinical probing depth were achieved postsurgery and remained unchanged during the first 6 years. The long-term clinical and radiographic findings, however, indicated that the attachment developed at the root-bone interface may not have been a true attachment and may have been more vulnerable to pathogenic local agents. These observations may help the clinician to interpret the clinical and radiographic changes that occur in the area of a bony defect following the use of a bone graft.

  12. Autogenic-feedback training: A preventive method for space adaptation syndrome

    NASA Technical Reports Server (NTRS)

    Cowings, Patricia S.; Sharp, Joseph C.; Toscano, William B.; Kamiya, Joe; Miller, Neal E.

    1987-01-01

    The progress made to date on the reduction of data for Spacelab 3 Shuttle experiment, No. 3AFT23 is reported. Four astronauts participated as subjects in this experiment. Crewmen A and B served as treatment subjects (i.e., received preflight training for control of their own motion sickness symptoms) and Crewmen C and D served as control (i.e., did not receive training). A preliminary evaluation of Autogenic Feedback Training (AFT) was made from visual inspections of graphs that were generated from the preflight and inflight and inflight physiological data which included: (1) Baseline rotating chair tests for all crewmen; (2) Posttraining rotating chair tests of treatment groups subjects; (3) Preflight data from Joint Integrated Simulations for all crewmen; and (4) Flight data for all crewmen during mission days 0 through 4, and mission day 6 for treatment subjects only. A summary of the findings suggested by these data is outlined.

  13. [Dynamics of osteogenesis after inoculation of autogenic mesenchymal stem cells of adipose tissue].

    PubMed

    Grygoryan, A S; Orlov, A A; Saburina, I N; Repin, B C; Sisoev, S D

    2015-01-01

    Experiment was conducted on 40 rats of Wister line. On the artificially reproduced experimental model autogenic mesenchimal stem cells (MSC) of adipose tissue were inoculated in space between bone autograph of tibia and mandible. MSC wasn't inoculated in the comparison group. Formation of a new bone substance in space between an autograph and mandible bone was observed. It was clear that after 120 days (180 days), there was a statistically significant decline of the area occupied by an immature fibroreticular bone. Described phenomenon, presumably, could be explained as a result of decline of the number of active cells in the population of inoculated MSC according to phenomenon of limited number divisions of cells on telomeres, described by Hayflick L. and Moorhead P.S.

  14. Use of autogenic and allogenic malleus in tympanic membrane to footplate assembly - long-term results.

    PubMed

    Mahadevaiah, A; Parikh, Bhavin

    2009-03-01

    The objective of this study was to assess the functional performance and long-term stability of autogenic and allogenic malleus used for ossiculoplasty as tympanic membrane to footplate assembly. A retrospective study of 119 patients who underwent such ossiculoplasty in closed cavity mastoidectomy from 1989-2004 was carried out. There was no extrusion in any of our cases. Serviceable hearing (<20 dB air bone gap closure) was achieved in 24 out of 37 (65%) over long-term follow up of more than 1 year (mean and median for follow up being 37.4 and 30 months respectively). Thus malleus ossicle graft give acceptable long-term hearing results in one of the most difficult ossiculoplasty situations (absence of stapes suprastructure and malleus) with virtually no extrusion problems.

  15. Autogenic-Feedback Training for the Control of Space Motion Sickness

    NASA Technical Reports Server (NTRS)

    Cowings, Patricia S.; Toscano, W. B.

    1994-01-01

    This paper presents case-studies of 9 shuttle crewmembers (prime and alternates) and one U.S. Navy F-18 pilot, as they participated in all preflight training and testing activities in support of a life sciences flight experiment aboard Spacelab-J, and Spacelab-3. The primary objective of the flight experiment was to determine if Autogenic-feedback training (AFT), a physiological self-regulation training technique would be an effective treatment for motion sickness and space motion sickness in these crewmembers. Additional objectives of this study involved the examining human physiological responses to motion sickness on Earth and in space, as well as developing predictive criteria for susceptibility to space motion sickness based on ground-based data. Comparisons of these crewmembers are made to a larger set of subjects from previous experiments (treatment and "test-only" controls subjects). This paper describes all preflight methods, results and proposed changes for future tests.

  16. [The results of autogenic training in patients with ischemic heart disease after an aortocoronary bypass operation].

    PubMed

    Rakov, A L; Mandrykin, Iu V; Zamotaev, Iu N

    1997-02-01

    Were studied psychovegetative and somatic correlations in 115 patients with ischemic heart disease, having aortocoronary shunting operation and being at the sanatorium stage of the medical rehabilitation. To 70 patients was been carried out treatment with application of autogenous training (AT), to 45--without use of AT. The research has confirmed the presence in the patients psychological disadaptation, expressed essentially in asthenoneurotic and hypochondriac reactions. Is established, that estimation of expressiveness of emotional tension, investigated with the aid of Spilberger's psychometric scale, can be confirmed by parameters of peroxide oxidation of lipids and mathematical analysis of heart rythm. The use of variant of training modified by the authors has revealed improvement of clinical parameters, reflecting health state of the patients, which correlate with the data of the psychological test and the results of bicycle ergometry [correction of veloergometry].

  17. Effects of autogenic training and antihypertensive agents on circadian and circaseptan variation of blood pressure.

    PubMed

    Watanabe, Yoshihiko; Cornélissen, Germaine; Watanabe, Misako; Watanabe, Fumihiko; Otsuka, Kuniaki; Ohkawa, Shi-ichiro; Kikuchi, Takenori; Halberg, Franz

    2003-10-01

    Even when the daily blood pressure mean is acceptable, too large a circadian amplitude of blood pressure largely increases cardiovascular disease risk. Autogenic training (N = 11), a non-pharmacologic intervention capable of lowering an excessive blood pressure variability, may be well-suited for MESOR-normotensive patients diagnosed with circadian-hyper-amplitude-tension (CHAT). Not all anti-hypertensive drugs affect blood pressure variability. Accordingly, long-acting carteolol (N = 11) and/or atenolol (N = 8) may be preferred to captopril retard (N = 13), nilvadipine (N = 8), or amlodipine (N = 7) for midline-estimating statistic of rhythm (MESOR)-hypertensive patients with CHAT. Prospective outcome studies are needed to assess whether the relative merits of these treatments are in keeping with their effects on blood pressure and blood pressure variability.

  18. Digital Reconstruction with a Nonfrozen Osteotendinous Allograft, Nerve Allografts, and Autogenous Radial Free Flap.

    PubMed

    Iglesias, Martin; Butrón, Patricia; Palafox, Damian; Cruz-Reyes, Angel U

    2015-08-01

    A 21-year-old man underwent amputation of his second to fifth fingers at the proximal phalanx level on the right hand. The third and fourth fingers were reconstructed with 2 toe-to-hand free transfers. The fifth digit was reconstructed with a nonfrozen osteotendinous allograft, nerve allografts, and autogenous radial free flap without immunosuppression. The patient was lost to follow-up for 19 years. He received no rehabilitation. He reported that he had experienced no adverse reactions to the materials or the graft, or infection, or fractures. No additional surgical procedures were performed. Today, the digit is functional and has acceptable aesthetic appearance. This outcome is similar to those obtained in digits reconstructed with frozen osteotendinous allografts and autologous cutaneous covers and opens the possibility for future research.

  19. Autogenous wisdom tooth transplantation: A case series with 6-9 months follow-up

    PubMed Central

    Nimčenko, Tatjana; Omerca, Gražvydas; Bramanti, Ennio; Cervino, Gabriele; Laino, Luigi; Cicciù, Marco

    2014-01-01

    Tooth transplantation can be considered a valid and predictable treatment option for rehabilitating young patients with permanent teeth loss. This study presents several cases of successful autogenous tooth transplantation with a 6-9 months follow-up. Tooth auto-transplantation can be considered a reasonable option for replacing missing teeth when a donor tooth is available. The auto-transplantation of a right mandibular third molar with compromised function and esthetics to replace the residual roots resulting from coronal destruction due to extensive carious lesion of the second molar in the same quadrant as shown in the presented cases can result a viable treatment alternative especially in a young patient that cannot undergo dental implant therapy. Transplantation of mature third molar seems to be a promising method for replacing a lost permanent molar tooth and restoring esthetics and function. This clinical procedure showed excellent functional and esthetical long-term results in the analyzed cases. PMID:25540668

  20. Reconstruction of interdental papilla using autogenous bone and connective tissue grafts

    PubMed Central

    Muthukumar, Santhanakrishnan; Ajit, Pooja; Sundararajan, Shiyamali; Rao, Suresh Ranga

    2016-01-01

    Previous studies have reported the management of Class I and II papillary defects, but knowledge on Class III defects, estimated to have a poor periodontal prognosis, remains minimal. In this case report, a Class III papillary defect reconstruction was attempted mainly since the patient reported with difficulty in phonetics. In Stage I, autogenous bone graft from the maxillary tuberosity and subepithelial connective tissue graft was augmented to decrease the distance between the interdental bone crest and contact point, simultaneously achieving a switch in the periodontal biotype. In Stage II, subepithelial connective tissue graft was augmented to achieve papillary fill. To avoid manual errors associated with quantifying the posttreatment outcomes, image data processing ImageJ software was used to assess the length, perimeter, and surface area of papillary loss using the preoperative images.

  1. Endovascular Treatment of Autogenous Radiocephalic Fistulas with the 'Eighth Note' Deformity for Hemodialysis

    SciTech Connect

    Weng Meijui; Chen, Matt Chiung-Yu; Chi Wenche; Liu Yichun; Chien Kofen; Liang Hueilung; Pan, Huay-Ben

    2010-02-15

    The purpose of this paper is to describe a unique 'eighth note' deformity of the autogenous radiocephalic fistula for hemodialysis and to retrospectively evaluate the efficacy and safety of its endovascular treatment. Over 3 years, a total of 808 patients and 558 autogenous radiocephalic fistulas were treated for vascular access dysfunction or thrombosis. These included 14 fistulas in 14 patients (9 men, 5 women; mean age, 58.2 {+-} 2.8 years; range 27-79 years) whose fistulograms before treatment resembled a musical note, the eighth note. Endovascular treatment sought to remodel the deformed vascular access to a classic radiocephalic fistula and increase the number of cannulation sites available for hemodialysis. The technical and clinical success rates were each 92.8% (13/14). Fistula remodeling was successful in 13 patients. The postintervention primary patency was 100% at 90 days, 91.7 {+-} 0.8% at 120 days, 78.6 {+-} 13.9% at 180 days, 62.9 {+-} 17.9% at 360 days, 31.4 {+-} 24.0% at 540 days, and 0% at 720 days. The postintervention secondary patency was 100% at 90 days, 100% at 120 days, 100% at 180 days, 85.7 {+-} 13.2% at 360 days, and 85.7 {+-} 13.2% at 720 days. No major complications were noted. Minor complications were found in 71.4% of patients, all of which resolved spontaneously. In conclusion, endovascular treatment of fistulas with the eighth note deformity can effectively increase the number of available cannulation sites, facilitate fistula maturation, and facilitate thromboaspiration after fistula thrombosis.

  2. Perceptual shrinkage of a one-way motion path with high-speed motion

    PubMed Central

    Nakajima, Yutaka; Sakaguchi, Yutaka

    2016-01-01

    Back-and-forth motion induces perceptual shrinkage of the motion path, but such shrinkage is hardly perceived for one-way motion. If the shrinkage is caused by temporal averaging of stimulus position around the endpoints, it should also be induced for one-way motion at higher motion speeds. In psychophysical experiments with a high-speed projector, we tested this conjecture for a one-way motion stimulus at various speeds (4–100 deg/s) along a straight path. Results showed that perceptual shrinkage of the motion path was robustly observed in higher-speed motion (faster than 66.7 deg/s). In addition, the amount of the forwards shift at the onset position was larger than that of the backwards shift at the offset position. These results demonstrate that high-speed motion can induce shrinkage, even for a one-way motion path. This can be explained by the view that perceptual position is represented by the integration of the temporal average of instantaneous position and the motion representation. PMID:27464844

  3. A Pore-Centric Model for Combined Shrinkage and Gas Porosity in Alloy Solidification

    NASA Astrophysics Data System (ADS)

    Khalajzadeh, Vahid; Carlson, Kent D.; Backman, Daniel G.; Beckermann, Christoph

    2017-04-01

    A unified model has been developed for combined gas- and shrinkage-induced pore formation during solidification of metal alloys. The model is based on a pore-centric approach, in which the temporal evolution of the pore radius is calculated as a function of cooling rate, thermal gradient, gas diffusion, and shrinkage. It accounts for the effect of porosity formation on the liquid velocity within the mushy zone. Simulations for an aluminum alloy show that the porosity transitions smoothly from shrinkage-induced to gas-induced as the Niyama value is increased. A Blake (cavitation) instability is observed to occur when the porosity is both gas- and shrinkage-driven. A revised dimensionless Niyama curve for pure shrinkage is presented. The experimentally observed gas porosity trend that the pore volume decreases with increasing cooling rate is well predicted. The pore-centric formulation allows the present model to be solved locally, at any point in a casting, during a regular casting simulation.

  4. A Pore-Centric Model for Combined Shrinkage and Gas Porosity in Alloy Solidification

    NASA Astrophysics Data System (ADS)

    Khalajzadeh, Vahid; Carlson, Kent D.; Backman, Daniel G.; Beckermann, Christoph

    2017-01-01

    A unified model has been developed for combined gas- and shrinkage-induced pore formation during solidification of metal alloys. The model is based on a pore-centric approach, in which the temporal evolution of the pore radius is calculated as a function of cooling rate, thermal gradient, gas diffusion, and shrinkage. It accounts for the effect of porosity formation on the liquid velocity within the mushy zone. Simulations for an aluminum alloy show that the porosity transitions smoothly from shrinkage-induced to gas-induced as the Niyama value is increased. A Blake (cavitation) instability is observed to occur when the porosity is both gas- and shrinkage-driven. A revised dimensionless Niyama curve for pure shrinkage is presented. The experimentally observed gas porosity trend that the pore volume decreases with increasing cooling rate is well predicted. The pore-centric formulation allows the present model to be solved locally, at any point in a casting, during a regular casting simulation.

  5. Control of polymerization shrinkage and stress in nanogel-modified monomer and composite materials

    PubMed Central

    Moraes, Rafael R.; Garcia, Jeffrey W.; Barros, Matthew D.; Lewis, Steven H.; Pfeifer, Carmem S.; Liu, JianCheng; Stansbury, Jeffrey W.

    2011-01-01

    Objectives This study demonstrates the effects of nano-scale prepolymer particles as additives to model dental monomer and composite formulations. Methods Discrete nanogel particles were prepared by solution photopolymerization of isobornyl methacrylate and urethane dimethacrylate in the presence of a chain transfer agent, which also provided a means to attach reactive groups to the prepolymer. Nanogel was added to triethylene glycol dimethacrylate (TEGDMA) in increments between 5 and 40 wt% with resin viscosity, reaction kinetics, shrinkage, mechanical properties, stress and optical properties evaluated. Maximum loading of barium glass filler was determined as a function of nanogel content and composites with varied nanogel content but uniform filler loading were compared in terms of consistency, conversion, shrinkage and mechanical properties. Results High conversion, high molecular weight internally crosslinked and cyclized nanogel prepolymer was efficiently prepared and redispersed into TEGDMA with an exponential rise in viscosity accompanying nanogel content. Nanogel addition at any level produced no deleterious effects on reaction kinetics, conversion or mechanical properties, as long as reactive nanogels were used. A reduction in polymerization shrinkage and stress was achieved in proportion to nanogel content. Even at high nanogel concentrations, the maximum loading of glass filler was only marginally reduced relative to the control and high strength composite materials with low shrinkage were obtained. Significance The use of reactive nanogels offers a versatile platform from which resin and composite handling properties can be adjusted while the polymerization shrinkage and stress development that challenge the adhesive bonding of dental restoratives are controllably reduced. PMID:21388669

  6. Shrinkage and growth compensation in common sunflowers: refining estimates of damage

    USGS Publications Warehouse

    Sedgwick, James A.; Oldemeye, John L.; Swenson, Elizabeth L.

    1986-01-01

    Shrinkage and growth compensation of artificially damaged common sunflowers (Helianthus annuus) were studied in central North Dakota during 1981-1982 in an effort to increase accuracy of estimates of blackbird damage to sunflowers. In both years, as plants matured damaged areas on seedheads shrank at a greater rate than the sunflower heads themselves. This differential shrinkage resulted in an underestimation of the area damaged. Sunflower head and damaged-area shrinkage varied widely by time and degree of damage and by size of the seedhead damaged. Because variation in shrinkage by time of damage was so large, predicting when blackbird damage occurs may be the most important factor in estimating seed loss. Yield'occupied seed area was greater (P < 0.05) for damaged than undamaged heads and tended to increase as degree of damage inflicted increased, indicating growth compensation was occurring in response to lost seeds. Yields of undamaged seeds in seedheads damaged during early seed development were higher than those of heads damaged later. This suggested that there was a period of maximal response to damage when plants were best able to redirect growth to seeds remaining in the head. Sunflowers appear to be able to compensate for damage of ≤ 15% of the total hear area. Estimates of damage can be improved by applying empirical results of differential shrinkage and growth compensations.

  7. Concentration-dependent specimen shrinkage in iodine-enhanced microCT

    PubMed Central

    Vickerton, Paula; Jarvis, Jonathan; Jeffery, Nathan

    2013-01-01

    Iodine potassium iodide (I2KI) solution can be employed as a contrast agent for the visualisation of soft tissue structures in micro-computed tomography studies. This technique provides high resolution images of soft tissue non-destructively but initial studies suggest that the stain can cause substantial specimen shrinkage. The degree of specimen shrinkage, and potential deformation, is an important consideration when using the data for morphological studies. Here we quantify the macroscopic volume changes in mouse skeletal muscle, cardiac muscle and cerebellum as a result of immersion in the common fixatives 10% phosphate-buffered formal saline, 70% ethanol and 3% glutaraldehyde, compared with I2KI staining solution at concentrations of 2, 6, 10 and 20%. Immersion in the I2KI solution resulted in dramatic changes of tissue volume, which were far larger than the shrinkage from formalin fixation alone. The degree of macroscopic change was most dependent upon the I2KI concentration, with severe shrinkage of 70% seen in solutions of 20% I2KI after 14 days' incubation. When using this technique care needs to be taken to use the lowest concentration that will give adequate contrast to minimise artefacts due to shrinkage. PMID:23721431

  8. Peridynamic model for fatigue cracking.

    SciTech Connect

    Silling, Stewart Andrew; Abe Askari

    2014-10-01

    The peridynamic theory is an extension of traditional solid mechanics in which the field equations can be applied on discontinuities, such as growing cracks. This paper proposes a bond damage model within peridynamics to treat the nucleation and growth of cracks due to cyclic loading. Bond damage occurs according to the evolution of a variable called the "remaining life" of each bond that changes over time according to the cyclic strain in the bond. It is shown that the model reproduces the main features of S-N data for typical materials and also reproduces the Paris law for fatigue crack growth. Extensions of the model account for the effects of loading spectrum, fatigue limit, and variable load ratio. A three-dimensional example illustrates the nucleation and growth of a helical fatigue crack in the torsion of an aluminum alloy rod.

  9. 46 CFR 59.10-5 - Cracks.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Cracks. 59.10-5 Section 59.10-5 Shipping COAST GUARD... APPURTENANCES Welding Repairs to Boilers and Pressure Vessels in -Service § 59.10-5 Cracks. (a) Cracks extending... cracks are veed out so that complete penetration of the weld metal is secured. (b) Circumferential...

  10. Cocaine/Crack: The Big Lie.

    ERIC Educational Resources Information Center

    National Inst. on Drug Abuse (DHHS/PHS), Rockville, MD.

    This pamphlet focuses on cocaine and crack use and the addictive nature of cocaine/crack. It contains a set of 21 questions about crack and cocaine, each accompanied by a clear and complete response. Interspersed throughout the booklet are photographs and quotes from former cocaine or crack users/addicts. Questions and answers focus on what…

  11. Shaft vibrations in turbomachinery excited by cracks

    NASA Technical Reports Server (NTRS)

    Grabowski, B.

    1982-01-01

    During the past years the dynamic behavior of rotors with cracks has been investigated mainly theoretically. This paper deals with the comparison of analytical and experimental results of the dynamics of a rotor with an artificial crack. The experimental results verify the crack model used in the analysis. They show the general possibility to determine a crack by extended vibration control.

  12. 46 CFR 59.10-5 - Cracks.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... APPURTENANCES Welding Repairs to Boilers and Pressure Vessels in -Service § 59.10-5 Cracks. (a) Cracks extending... corrugated furnaces may be repaired by welding provided any one crack does not exceed 20 inches in length. (e... any direction, nor more than a total of four cracks in a drum, and further provided the welding...

  13. Allogenic forcing of autogenic processes: inferences from an aggregated process-based model of fluvio-deltaic systems

    NASA Astrophysics Data System (ADS)

    Karamitopoulos, P.; Weltje, G.; Dalman, R.

    2011-12-01

    Spatial and temporal variability of sediment storage in fluvio-deltaic sedimentary systems is controlled by the interplay of allogenic and autogenic processes. In order to investigate the effects of this interplay on the resulting stratigraphy at varying spatio-temporal scales, we carried out a series of numerical experiments using an aggregated process-based model of fluvio-deltaic systems (SIMCLAST), which combines diffusive and advective transport with sub-grid channel stability algorithms in the fluvial domain. New distributary channels occur by avulsions under conditions of local superelevation or through bifurcations due to mouth bar deposition. A series of numerical experiments were performed under forcing by glacio-eustatic sealevel cycles in the order of 100 kyr. Initial conditions of all experiments are represented by classic continental-margin topography with a shelf break. In this scenario, erosional features (canyons) are developed when sea level falls below the shelf break. Sediment supply and liquid discharge remain constant throughout the experiments. In order to characterize the topographic variability during the experiments, we used a difference measure obtained by summation of local changes in net sediment accumulation rates across the entire model domain. Long-term average variability (10 kyr resolution) correlates strongly with the allogenic sea-level signal. The long-term variability reaches a maximum around the time interval corresponding to isochronous maximum flooding surfaces, when retrogradation gives way to a new episode of progradation. Long-term mean variability is lowest during periods of sea-level fall, when incision restricts sediment dispersal. Increasing the time resolution of our difference measure allows recognition of numerous small peaks which correspond to local changes in sediment accumulation rates induced by autogenic processes (avulsions and bifurcations). The amplitudes of these peaks are related to the rate of change of

  14. Microscopic origins of stochastic crack growth

    NASA Astrophysics Data System (ADS)

    Pardee, W. J.; Morris, W. L.; Cox, B. N.

    Physical arguments are made to obtain a mathematical model of the stochastic growth of surface fatigue cracks in a ductile metal alloy. The model is a set of coupled partial differential equations for the expected statistical density of cracks per unit area. The differential equations describe the smooth, deterministic local evolution of crack states, with the stochastic effects of abrupt local changes of material in the crack path appearing as transitions between distinct subspaces of single crack state space. Results are related to observables such as statistical distributions of crack growth rate and of time for at least one crack to reach macroscopic length.

  15. The kinetics of hydrocarbon cracking

    SciTech Connect

    Groten, W.A.; Wojciechowski, B.W. )

    1993-03-01

    A general kinetic model which describes the catalytic cracking of pure hydrocarbons is presented. The model includes a monomolecular cracking path based on the Langmuir adsorption isotherm as well as a bimolecular path, following Rideal kinetics, which accounts for the possibility of a chain cracking mechanism being involved. Catalyst decay is accounted for using the time-on-stream-decay function. Fitting of experimental data from n-nonane cracking on USHY at 673 K, combined with Monte Carlo simulations indicates that, in that case, the total catalytic activity could include between 0 and 90% of activity due to chain processes. This large margin of error stems from the combined effects of a large decay rate, forcing the experimenter to use average conversion data, and of experimental error. Fitting of the model to previously published cracking data for 2-methylpentane on USHY showed that the model lacks a suitable parameter to account for thermal reactions which were not accounted for in the original data set. This observation supports the impression that the model is sensitive to departures from the postulated mechanism. The above kinetic model has also been fitted to the results of n-nonane cracking at three temperatures as well as to previously published data for various other linear paraffins. 32 refs., 17 figs., 6 tabs.

  16. Low-shrink composite resins: a review of their history, strategies for managing shrinkage, and clinical significance.

    PubMed

    Pitel, Mark L

    2013-09-01

    Despite numerous advances in composite resin technology over the course of many decades, shrinkage behavior and the resultant stresses inherent to direct placed composite restorations continue to challenge clinicians. This overview of composite resins includes a review of their history and development along with a discussion of strategies for reducing polymerization shrinkage. An assessment of the clinical significance of these materials is also provided, including a discussion of the differences between polymerization shrinkage and stress, incremental layering versus bulk placement, and the emergence of lower shrinkage stress monomer chemistry.

  17. Mitigation of Crack Damage in Metallic Materials

    NASA Technical Reports Server (NTRS)

    Leser, Patrick E.; Newman, John A.; Smith, Stephen W.; Leser, William P.; Wincheski, Russell A.; Wallace, Terryl A.; Glaessgen, Edward H.; Piascik, Robert S.

    2014-01-01

    A system designed to mitigate or heal crack damage in metallic materials has been developed where the protected material or component is coated with a low-melting temperature film. After a crack is formed, the material is heated, melting the film which then infiltrates the crack opening through capillary action. Upon solidification, the healing material inhibits further crack damage in two ways. While the crack healing material is intact, it acts like an adhesive that bonds or bridges the crack faces together. After fatigue loading damages, the healing material in the crack mouth inhibits further crack growth by creating artificially-high crack closure levels. Mechanical test data show that this method sucessfully arrests or retards crack growth in laboratory specimens.

  18. Fatigue Growth and Closure of Short Cracks

    DTIC Science & Technology

    1989-06-03

    stLdy has been carried out to investigate the growth and closure behavior of shortýýcracks in 2024-T351 aluminum alloy and four different conditions of...that short cracks show lessclosure behavior than longcracks. The estimates of initlal.crack lengths based on linearelastic data were made. tThese...anomalous behavior of short cracks. Advances in small crack growth have enabled increasingly quantitative studies that affect initi- ation and growth at

  19. Hormone replacement therapy and age-related brain shrinkage: regional effects.

    PubMed

    Raz, Naftali; Rodrigue, Karen M; Kennedy, Kristen M; Acker, James D

    2004-11-15

    Neuroprotective properties of estrogen have been established in animal models, but clinical trials of hormone replacement therapy (HRT) produced contradictory results. We examined the impact of HRT on age-related regional changes in human brain volume. Six brain regions were measured twice, five years apart, in 12 healthy women who took HRT and in matched controls who did not. The controls showed a typical pattern of differential brain shrinkage in the association cortices and the hippocampus with no change in the primary visual cortex. In contrast, women who took HRT showed comparable shrinkage of the hippocampus but no significant shrinkage of the neocortex. Future large scale studies may benefit from applying regional rather than global measures in assessment of brain integrity.

  20. Fast approach to infrared image restoration based on shrinkage functions calibration

    NASA Astrophysics Data System (ADS)

    Zhang, Chengshuo; Shi, Zelin; Xu, Baoshu; Feng, Bin

    2016-05-01

    High-quality image restoration in real time is a challenge for infrared imaging systems. We present a fast approach to infrared image restoration based on shrinkage functions calibration. Rather than directly modeling the prior of sharp images to obtain the shrinkage functions, we calibrate them for restoration directly by using the acquirable sharp and blurred image pairs from the same infrared imaging system. The calibration method is employed to minimize the sum of squared errors between sharp images and restored images from the blurred images. Our restoration algorithm is noniterative and its shrinkage functions are stored in the look-up tables, so an architecture solution of pipeline structure can work in real time. We demonstrate the effectiveness of our approach by testing its quantitative performance from simulation experiments and its qualitative performance from a developed wavefront coding infrared imaging system.

  1. Hormone-dependent shrinkage of a sphenoid wing meningioma after pregnancy: case report.

    PubMed

    Kerschbaumer, Johannes; Freyschlag, Christian F; Stockhammer, Günter; Taucher, Susanne; Maier, Hans; Thomé, Claudius; Seiz-Rosenhagen, Marcel

    2016-01-01

    Meningiomas are known to be associated with female sex hormones. Worsening neurological symptoms or newly diagnosed meningiomas have been described in the context of elevated levels of sex hormones, for example, in pregnancy. To the authors' knowledge, tumor shrinkage after the normalization of hormones has not been described, even if it is known that neurological deficits due to meningioma compression may improve after giving birth. A 32-year-old female patient presented with severe headache and vision disturbances at the end of her second pregnancy. Magnetic resonance imaging revealed an extended mass at the lateral left-sided sphenoid wing that was suspected to be a meningioma. After delivery, the patient's symptoms improved, and MRI obtained 2 months postpartum showed significant shrinkage of the lesion. Significant tumor shrinkage can occur after pregnancy. Thus, repeat imaging is indicated in these patients.

  2. Accurate ranking of differentially expressed genes by a distribution-free shrinkage approach.

    PubMed

    Opgen-Rhein, Rainer; Strimmer, Korbinian

    2007-01-01

    High-dimensional case-control analysis is encountered in many different settings in genomics. In order to rank genes accordingly, many different scores have been proposed, ranging from ad hoc modifications of the ordinary t statistic to complicated hierarchical Bayesian models. Here, we introduce the "shrinkage t" statistic that is based on a novel and model-free shrinkage estimate of the variance vector across genes. This is derived in a quasi-empirical Bayes setting. The new rank score is fully automatic and requires no specification of parameters or distributions. It is computationally inexpensive and can be written analytically in closed form. Using a series of synthetic and three real expression data we studied the quality of gene rankings produced by the "shrinkage t" statistic. The new score consistently leads to highly accurate rankings for the complete range of investigated data sets and all considered scenarios for across-gene variance structures.

  3. Dental composite resins: measuring the polymerization shrinkage using optical fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Ottevaere, H.; Tabak, M.; Chah, K.; Mégret, P.; Thienpont, H.

    2012-04-01

    Polymerization shrinkage of dental composite materials is recognized as one of the main reasons for the development of marginal leakage between a tooth and filling material. As an alternative to conventional measurement methods, we propose optical fiber Bragg grating (FBG) based sensors to perform real-time strain and shrinkage measurements during the curing process of dental resin cements. We introduce a fully automated set-up to measure the Bragg wavelength shift of the FBG strain sensors and to accurately monitor the linear strain and shrinkage of dental resins during curing. Three different dental resin materials were studied in this work: matrix-filled BisGMA-based resins, glass ionomers and organic modified ceramics.

  4. Shrinkage of polyurethane molecular stamp fixed on epoxy resin modified glass substrate

    NASA Astrophysics Data System (ADS)

    Liu, Zhengchun; He, Quanguo; Xiao, Pengfeng; Tang, Jianxin; He, Nongyue; Lu, Zuhong

    2003-01-01

    The shrinkage of polyurethane stamps used for the in situ synthesis of DNA microarrays via molecular stamping method was studied with Micron XYZ Scope. It was found that the polyurethane stamp fixed on the epoxy resin modified glass strongly and showed minimum linear shrinkage. The linear shrinkage of the whole polyurethane stamp and that of each feature of polyurethane stamp were controlled within 0.0341% and 0.309%, respectively, which were due to the strong van der Waals forces and hydrogen bonds between polyurethane and epoxy resin. It was also confirmed by scanning electron microscope that the polyurethane stamp fixed on the epoxy resin modified glass replicated the patterns of motherboard with a high fidelity. All these underlay the synthesis of DNA microarray through molecular stamping method.

  5. Shrinkage control in a photopolymerizable hybrid solgel material for holographic recording.

    PubMed

    Ramos, Gonzalo; Alvarez-Herrero, Alberto; Belenguer, Tomas; del Monte, Francisco; Levy, David

    2004-07-10

    We report the correction of the shrinkage observed during UV postrecording curing in a holographic solgel material that was recently achieved by the use of various chemical formulations for the composition of the hybrid supporting matrix. We found that a chemical modification of the matrix noticeably attenuates the shrinkage (from 1.3% to 0.4% of the material's initial thickness with the inclusion of just 20% tetramethylorthosilicate), providing a material with improved stability for permanent data storage applications. The holographic properties of samples with different binders are also reported. In addition, a theoretical study has revealed the way by which to compensate for angular deviation in the Bragg condition during UV postrecording by tailoring the binder shrinkage (s), the maximum refractive-index modulation capability of the photosensitive mixture (deltan), or both.

  6. Cracks in Utopia

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Many of the craters found on the northern plains of Mars have been partly filled or buried by some material (possibly sediment). The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image presented here (MOC2-136b, above left) shows a high-resolution view of a tiny portion of the floor of one of these northern plains craters. The crater, located in Utopia Planitia at 44oN, 258oW, is shown on the right (MOC2-136a)with a small white box to indicate the location of the MOC image. The MOC image reveals that the material covering the floor of this crater is cracked and pitted. The origin and source of material that has been deposited in this crater is unknown.

    The MOC image was acquired in June 1999 and covers an area only 1.1 kilometers (0.7 miles) wide at a resolution of 1.8 meters (6 feet) per pixel. The context picture is a mosaic of Viking 2 orbiter images 010B53 and 010B55, taken in 1976. Both images are illuminated from the left. Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  7. Regional Brain Shrinkage over Two Years: Individual Differences and Effects of Pro-Inflammatory Genetic Polymorphisms

    PubMed Central

    Persson, N.; Ghisletta, P.; Dahle, C.L.; Bender, A.R.; Yang, Y.; Yuan, P.; Daugherty, A.M.; Raz, N.

    2014-01-01

    We examined regional changes in brain volume in healthy adults (N = 167, age 19-79 years at baseline; N = 90 at follow-up) over approximately two years. With latent change score models, we evaluated mean change and individual differences in rates of change in 10 anatomically-defined and manually-traced regions of interest (ROIs): lateral prefrontal cortex (LPFC), orbital frontal cortex (OF), prefrontal white matter (PFw), hippocampus (HC), parahippocampal gyrus (PhG), caudate nucleus (Cd), putamen (Pt), insula (In), cerebellar hemispheres (CbH), and primary visual cortex (VC). Significant mean shrinkage was observed in the HC, CbH, In, OF, and the PhG, and individual differences in change were noted in all regions, except the OF. Pro-inflammatory genetic variants mediated shrinkage in PhG and CbH. Carriers of two T alleles of interleukin-1β (IL-1βC-511T, rs16944) and a T allele of methylenetetrahydrofolate reductase (MTHFRC677T, rs1801133) polymorphisms showed increased PhG shrinkage. No effects of a pro-inflammatory polymorphism for C-reactive protein (CRP-286C>A>T, rs3091244) or apolipoprotein (APOE) ε4 allele were noted. These results replicate the pattern of brain shrinkage observed in previous studies, with a notable exception of the LPFC thus casting doubt on the unique importance of prefrontal cortex in aging. Larger baseline volumes of CbH and In were associated with increased shrinkage, in conflict with the brain reserve hypothesis. Contrary to previous reports, we observed no significant linear effects of age and hypertension on regional brain shrinkage. Our findings warrant further investigation of the effects of neuroinflammation on structural brain change throughout the lifespan. PMID:25264227

  8. Regional brain shrinkage over two years: individual differences and effects of pro-inflammatory genetic polymorphisms.

    PubMed

    Persson, N; Ghisletta, P; Dahle, C L; Bender, A R; Yang, Y; Yuan, P; Daugherty, A M; Raz, N

    2014-12-01

    We examined regional changes in brain volume in healthy adults (N=167, age 19-79years at baseline; N=90 at follow-up) over approximately two years. With latent change score models, we evaluated mean change and individual differences in rates of change in 10 anatomically-defined and manually-traced regions of interest (ROIs): lateral prefrontal cortex (LPFC), orbital frontal cortex (OF), prefrontal white matter (PFw), hippocampus (Hc), parahippocampal gyrus (PhG), caudate nucleus (Cd), putamen (Pt), insula (In), cerebellar hemispheres (CbH), and primary visual cortex (VC). Significant mean shrinkage was observed in the Hc, CbH, In, OF, and PhG, and individual differences in change were noted in all regions, except the OF. Pro-inflammatory genetic variants modified shrinkage in PhG and CbH. Carriers of two T alleles of interleukin-1β (IL-1β C-511T, rs16944) and a T allele of methylenetetrahydrofolate reductase (MTHFR C677T, rs1801133) polymorphisms showed increased PhG shrinkage. No effects of a pro-inflammatory polymorphism for C-reactive protein (CRP-286C>A>T, rs3091244) or apolipoprotein (APOE) ε4 allele were noted. These results replicate the pattern of brain shrinkage observed in previous studies, with a notable exception of the LPFC, thus casting doubt on the unique importance of prefrontal cortex in aging. Larger baseline volumes of CbH and In were associated with increased shrinkage, in conflict with the brain reserve hypothesis. Contrary to previous reports, we observed no significant linear effects of age and hypertension on regional brain shrinkage. Our findings warrant further investigation of the effects of neuroinflammation on structural brain change throughout the lifespan.

  9. Studies of spinal shrinkage to evaluate low-back loading in the workplace.

    PubMed

    McGill, S M; van Wijk, M J; Axler, C T; Gletsu, M

    1996-01-01

    Measurement of spinal shrinkage (stadiometry) has been suggested to be a convenient measure of low-back load in workplace settings. This report documents three separate experiments that collectively form a central theme: Is the measurement of spinal shrinkage a suitable assessment technique to quantify the cumulative effect of loading on the low back given the many sources for variability in the signal? A stadiometer was fabricated to measure both sitting and standing height. The first experiment was to compare sitting with standing stature changes over time in an attempt to locate the major site of shrinkage. There were no statistically significant differences in stature change found between either the sitting or standing posture for any condition suggesting that nearly all height changes occur in the spine. The second experiment compared the cumulative effects from static load holding to dynamic load lifting. Some subjects experienced more shrinkage in the static task while others experienced more in the dynamic task. In the third experiment, subjects performed work-rest cycles consisting of periods of sitting and lifting, and repeated over two days, to examine the recovery phenomenon. No specific pattern emerged owing to unpredictable subject variability. The first general observation obtained from the results of all three experiments is that the response of subjects to a wide array of activities appears to be variable both within each subject and over repeated exposures to identical conditions on different days. While subject variability (and perhaps biological variability) is a liability, it may be feasible to develop load time integrals for load exposure in the future, since the asset of the spinal shrinkage approach appears to be that it is one of the few available techniques to assess cumulative loading for both isometric postures, prolonged sitting, repeated tasks and responds to the positive adaptive changes that occur from periods of rest. However, it

  10. Shrinkage Study of Polypropylene Films Laminated on Steel-Influence of the Conformation Processes

    NASA Astrophysics Data System (ADS)

    Ponçot, Marc; Martin, Julien; Dahoun, Abdesselam; Hiver, Jean-Marie; Bourson, Patrice; Verchère, Didier

    2011-05-01

    Nowadays, thermoplastic polymers do not cease to attract the interest of the industrialists as steel / polymer composites for various applications in several domains, such as the automotive and the packaging. The ratio between their wide range of thermo-mechanical properties and their low weight density make these materials a real alternative for the current solutions for the lightening and the reinforcement of structural pieces. Likewise, their working facility is a major asset for performing parts of complex geometry. In this paper, we highlight the narrow relationship between the microstructure of a small impact isotactic polypropylene film, either filled or not by mineral particles (calcite), and its behaviour towards shrinkage which can occur during thermal treatments above its melting temperature. This phenomenon of shrinkage is characterized by dimensional instabilities which can in particular, affect the life cycle of the material. Indeed, they may induce the partial delamination of the steel sheet which is consequently exposed to various environmental aggressions. Corrosive behaviour can occur and cause early breakdown of the material. Influences of the extrusion and stamping processes on the microstructure and the shrinkage are presented. The macromolecular chains orientation of the crystalline phase, the volume damage and the heating parameters are studied, and show a real impact on the phenomenon magnitude. An experimental setup was developed at the laboratory to measure in real-time and with good precision, the displacements induced by shrinkage and the microstructural evolution of the polymer film during different thermal cycles. Finally, an empirical law allowing the shrinkage prediction is presented, taking into account the deformation value and the initial degree of chains orientation. These studies and their results have led to the determination of the optimal parameters settings for the different conformation processes with the aim of reducing

  11. Formation and interpretation of dilatant echelon cracks.

    USGS Publications Warehouse

    Pollard, D.D.; Segall, P.; Delaney, P.T.

    1982-01-01

    The relative displacements of the walls of many veins, joints, and dikes demonstrate that these structures are dilatant cracks. We infer that dilatant cracks propagate in a principal stress plane, normal to the maximum tensile or least compressive stress. Arrays of echelon crack segments appear to emerge from the peripheries of some dilatant cracks. Breakdown of a parent crack into an echelon array may be initiated by a spatial or temporal rotation of the remote principal stresses about an axis parallel to the crack propagation direction. Near the parent-crack tip, a rotation of the local principal stresses is induced in the same sense, but not necessarily through the same angle. Incipient echelon cracks form at the parent-crack tip normal to the local maximum tensile stress. Further longitudinal growth along surfaces that twist about axes parallel to the propagation direction realigns each echelon crack into a remote principal stress plane. The walls of these twisted cracks may be idealized as helicoidal surfaces. An array of helicoidal cracks sweeps out less surface area than one parent crack twisting through the same angle. Thus, many echelon cracks grow from a single parent because the work done in creating the array, as measured by its surface area decreases as the number of cracks increases. -from Authors

  12. Autogenic-allogenic status affects interpond community similarity and species area relationship of macroparasites in the bluegill sunfish, Lepomis macrochirus, from a series of freshwater ponds in the Piedmont area of North Carolina.

    PubMed

    Fellis, K Joel; Esch, Gerald W

    2005-08-01

    The effects of autogenic-allogenic status on the species-area relationship and the relationship between geographic distance and intercommunity dissimilarity were investigated in macroparasite communities of the bluegill sunfish Lepomis macrochirus. Rank correlation analyses were used to examine the relationship between pond surface area and species richness of all species collectively and of autogenic species and allogenic species separately. A positive relationship was found for allogenic species, whereas there was no association for all species, nor was there an association when the study was restricted to autogenic species. Mantel tests were used to determine the relationship between geographic distance and community dissimilarity for all species and for autogenic and allogenic species independently. Total community dissimilarity and allogenic dissimilarity were found to be influenced by geographic distance, whereas autogenic dissimilarity was random with regard to interpond distances. These findings serve to illustrate the importance of the autogenic-allogenic dichotomy and demonstrate that dispersal ability can influence commonly observed ecological patterns.

  13. Observation of Intralaminar Cracking in the Edge Crack Torsion Specimen

    NASA Technical Reports Server (NTRS)

    Czabaj, Michael W.; Ratcliffe, James G.; Davidson, Barry D.

    2013-01-01

    The edge crack torsion (ECT) test is evaluated to determine its suitability for measuring fracture toughness associated with mode III delamination growth onset. A series of ECT specimens with preimplanted inserts with different lengths is tested and examined using nondestructive and destructive techniques. Ultrasonic inspection of all tested specimens reveals that delamination growth occurs at one interface ply beneath the intended midplane interface. Sectioning and optical microscopy suggest that the observed delamination growth results from coalescence of angled intralaminar matrix cracks that form and extend across the midplane plies. The relative orientation of these cracks is approximately 45 deg with respect to the midplane, suggesting their formation is caused by resolved principal tensile stresses arising due to the global mode-III shear loading. Examination of ECT specimens tested to loads below the level corresponding to delamination growth onset reveals that initiation of intralaminar cracking approximately coincides with the onset of nonlinearity in the specimen's force-displacement response. The existence of intralaminar cracking prior to delamination growth onset and the resulting delamination extension at an unintended interface render the ECT test, in its current form, unsuitable for characterization of mode III delamination growth onset. The broader implications of the mechanisms observed in this study are also discussed with respect to the current understanding of shear-driven delamination in tape-laminate composites.

  14. Mining pharmacovigilance data using Bayesian logistic regression with James-Stein type shrinkage estimation.

    PubMed

    An, Lihua; Fung, Karen Y; Krewski, Daniel

    2010-09-01

    Spontaneous adverse event reporting systems are widely used to identify adverse reactions to drugs following their introduction into the marketplace. In this article, a James-Stein type shrinkage estimation strategy was developed in a Bayesian logistic regression model to analyze pharmacovigilance data. This method is effective in detecting signals as it combines information and borrows strength across medically related adverse events. Computer simulation demonstrated that the shrinkage estimator is uniformly better than the maximum likelihood estimator in terms of mean squared error. This method was used to investigate the possible association of a series of diabetic drugs and the risk of cardiovascular events using data from the Canada Vigilance Online Database.

  15. Compressible cake filtration: monitoring cake formation and shrinkage using synchrotron X-rays

    SciTech Connect

    Bierck, B.R.; Wells, S.A.; Dick, R.I.

    1988-05-01

    High energy, highly collimated X-rays produced at the Cornell High Energy Synchrotron Sources (CHESS) enabled real-time suspended solids concentration measurements each second with 0.5 mm vertical separation in a kaolin filter cake. Suspended solids concentration profiles reflected expected effects of cumulative fluid drag forces. Shrinkage caused a significant increase in average cake suspended solids concentration after expiration of the slurry, and the saturated cake ultimately formed was virtually homogeneous. Shrinkage is consolidation under compressive forces created when capillary menisci form at air/liquid interfaces, and has a significant effect on cake structure in latter stages of compressible cake filtration.

  16. OPTIMAL SHRINKAGE ESTIMATION OF MEAN PARAMETERS IN FAMILY OF DISTRIBUTIONS WITH QUADRATIC VARIANCE

    PubMed Central

    Xie, Xianchao; Kou, S. C.; Brown, Lawrence

    2015-01-01

    This paper discusses the simultaneous inference of mean parameters in a family of distributions with quadratic variance function. We first introduce a class of semi-parametric/parametric shrinkage estimators and establish their asymptotic optimality properties. Two specific cases, the location-scale family and the natural exponential family with quadratic variance function, are then studied in detail. We conduct a comprehensive simulation study to compare the performance of the proposed methods with existing shrinkage estimators. We also apply the method to real data and obtain encouraging results. PMID:27041778

  17. Autogenous grafts for condylar reconstruction in treatment of TMJ ankylosis: current concepts and considerations for the future.

    PubMed

    Khadka, A; Hu, J

    2012-01-01

    Temporomandibular joint (TMJ) ankylosis is characterized by difficulty or inability to open the mouth due to fusion of the temporal and the mandible, resulting in facial symmetry/deformity, malocclusion and dental problems. The only treatment option for TMJ ankylosis is surgical with or without condylar reconstruction. Various autogenous grafts are available for condylar reconstruction after freeing the ankylotic mass such as costochondral, sternoclavicular, fibular, coronoid, and metatarsophalangeal. Costochondral graft is preferred by surgeons, but distraction osteogenesis is slowly gaining popularity and may ultimately become the standard procedure, providing a cost-effective approach with low morbidity and excellent functional outcomes. Tissue engineering is another budding field which has shown promising results in animal studies but has not been applied to humans. To date, there is no ideal autogenous graft for condylar reconstruction that satisfies the complex anatomy and the myriad of functions of a missing condyle.

  18. [Influence of transplantation of autogenic mezenhymal stem cells from the fatty tissues on osseogenic process (experimental research)].

    PubMed

    Orlov, A A; Saburina, I N; Sisoev, S D; Grigorian, A D

    2014-01-01

    In experiments on 48 rats of line Wistar, divided at 2 groups (first--basic group and 2-d group--group of comparison) through the use of morphological method was researched influence of mesenchymal stem cells (MSC) inoculated in the area of autogenic bone graft from tibia fixed at the surface of the jaw. The animals of group of comparison didn't get MSC. Time frames of watching: 21, 60, 120 and 180 days, 6 rats on the point of experiment in either of the two of the group. Data of this research had shown the intensification of bone formation process in the basic group of experiment under the action of the inoculation of autogenic MSC from adipose tissue, and as consequence of it, in eventual, merge of bone formations in a single entity.

  19. The effect of butyric acid with autogenous omental graft on healing of experimental Achilles tendon injury in rabbits

    PubMed Central

    Jahani, S; Moslemi, H. R.; Dehghan, M. M.; Sedaghat, R; Mazaheri Nezhad, R; Rezaee Moghaddam, D

    2015-01-01

    In this study, the role of local injection of butyric acid (BA) with autogenous omental graft was evaluated in healing of experimental Achilles tendon injury in rabbits. Nine adult male New Zealand rabbits were anesthetized and a partial thickness tenotomy was created on both hindlimbs. In treated group, omental graft was secured in place using BA soaked polygalactin 910 suture. In control group, the graft was sutured without BA. Butyric acid and normal saline were injected daily to treatment and control groups for three days, respectively. Based on the findings, on day 15 after injury, the tendon sections showed that healing rate in BA treated group was higher than that in control group. Furthermore, at days 28 and 45, comparison between BA treated and control groups demonstrated that BA increased the healing rate but with no significance. In summary, results of this study show that application of BA with autogenous omental graft can improve healing process of damaged Achilles tendon. PMID:27175160

  20. Hard and Soft Tissue Management of a Localized Alveolar Ridge Atrophy with Autogenous Sources and Biomaterials: A Challenging Clinical Case

    PubMed Central

    Andreoni, D.

    2016-01-01

    Particularly in the premaxillary area, the stability of hard and soft tissues plays a pivotal role in the success of the rehabilitation from both a functional and aesthetic aspect. The present case report describes the clinical management of a localized alveolar ridge atrophy in the area of the upper right canine associated with a thin gingival biotype with a lack of keratinized tissue. An autogenous bone block harvested from the chin associated with heterologous bone particles was used to replace the missing bone, allowing for a prosthetic driven implant placement. Soft tissues deficiency was corrected by means of a combined epithelialized and subepithelial connective tissue graft. The 3-year clinical and radiological follow-up demonstrated symmetric gingival levels of the upper canines, with physiological peri-implant probing depths and bone loss. Thus, the use of autogenous tissues combined with biomaterials might be considered a reliable technique in case of highly aesthetic demanding cases. PMID:27738534

  1. Fiber Bragg grating sensors as a tool to evaluate the influence of filler on shrinkage of geopolymer matrices

    NASA Astrophysics Data System (ADS)

    Campopiano, Stefania; Iadicicco, Agostino; Messina, Francesco; Ferone, Claudio; Cioffi, Raffaele

    2015-05-01

    Geopolymer matrices represent one of the main sustainable alternatives to ordinary Portland cement (OPC) and other clinker-based blended cements. Real scale applications are limited and a relevant amount of data is still needed to assess the early age and long-term behavior of these systems. Particularly, the early-age monitoring of geopolymers represent a key parameter for mix design optimization. Most of the available methods for the measurement of temperature evolution due to polycondensation kinetics and early age deformations are related to laboratory activities. The upscaling to in situ techniques represents a crucial step toward technological assessment. To this aim, authors propose to use Fiber Bragg Gratings (FBGs) embedded in the geopolymer matrices. Starting from a case study by authors related to the design of externally bonded fiber reinforced geopolymers for strengthening of existing structures, the matrix was optimized in terms of quartz filler content. The measurements carried out by means of FBG sensors allowed to reduce filler content respect to the abovementioned work. Particularly, quartz content can be reduced by 50%. The temperature associated to polycondensation was slightly below 65°C for the three studied systems, limiting the use of designed metakaolin geopolymer to non-massive structures, since thermal cracking could occur, unless further research will be able to assess the viability of retardants. The experimental results confirm that FBG represent an accurate method for simultaneous shrinkage and temperature measurements for geopolymers and the application in real scale structures for remote sensing could help to create database on inner temperatures and early age deformations.

  2. Properties evaluation of silorane, low-shrinkage, non-flowable and flowable resin-based composites in dentistry

    PubMed Central

    Reis, Rodrigo S.; Moro, André F.V.; Perez, Cesar R.; Pessôa, Bárbara M.; Dias, Katia R.H.C.

    2015-01-01

    Purpose. This study tested the null hypothesis that different classes of direct restorative dental materials: silorane-based resin, low-shrinkage and conventional (non-flowable and flowable) resin-based composite (RBC) do not differ from each other with regard to polymerization shrinkage, depth of cure or microhardness. Methods. 140 RBC samples were fabricated and tested by one calibrated operator. Polymerization shrinkage was measured using a gas pycnometer both before and immediately after curing with 36 J/cm2 light energy density. Depth of cure was determined, using a penetrometer and the Knoop microhardness was tested from the top surface to a depth of 5 mm. Results. Considering polymerization shrinkage, the authors found significant differences (p < 0.05) between different materials: non-flowable RBCs showed lower values compared to flowable RBCs, with the silorane-based resin presenting the smallest shrinkage. The low shrinkage flowable composite performed similarly to non-flowable with significant statistical differences compared to the two other flowable RBCs. Regarding to depth of cure, low-shrinkage flowable RBC, were most effective compared to other groups. Microhardness was generally higher for the non-flowable vs. flowable RBCs (p < 0.05). However, the values for low-shrinkage flowable did not differ significantly from those of non-flowable, but were significantly higher than those of the other flowable RBCs. Clinical Significance. RBCs have undergone many modifications as they have evolved and represent the most relevant restorative materials in today’s dental practice. This study of low-shrinkage RBCs, conventional RBCs (non-flowable and flowable) and silorane-based composite—by in vitro evaluation of volumetric shrinkage, depth of cure and microhardness—reveals that although filler content is an important determinant of polymerization shrinkage, it is not the only variable that affects properties of materials that were tested in this study

  3. A theoretical and experimental analysis of polymerization shrinkage of bone cement: A potential major source of porosity.

    PubMed

    Gilbert, J L; Hasenwinkel, J M; Wixson, R L; Lautenschlager, E P

    2000-10-01

    A theoretical basis for understanding polymerization shrinkage of bone cement is presented based on density changes in converting monomer to polymer. Also, an experimental method, based on dilatometry and the Archimedes' principle is presented for highly precise and accurate measurement of unconstrained volumetric shrinkage of bone cement. Furthermore, a theoretical and experimental analysis of polymerization shrinkage in a constrained deformational state is presented to demonstrate that porosity can develop due to shrinkage. Six bone-cement conditions (Simplex-Ptrade mark vacuum and hand mixed, Endurancetrade mark vacuum mixed, and three two-solution experimental bone cements with higher initial monomer levels) were tested for volumetric shrinkage. It was found that shrinkage varied statistically (p< or = 0.05) from 5.1% (hand-mixed Simplex-Ptrade mark) to 6.7% (vacuum-mixed Simplex-Ptrade mark) to 10.5% for a 0.6:1 (polymer g/monomer mL) two-solution bone cement. Shrinkage was highly correlated with initial monomer content (R(2) = 0.912) but with a lower than theoretically expected rate. This discrepancy was due to the presence of residual monomer after polymerization. Using previously determined residual monomer levels, the theoretic shrinkage analysis was shown to be predictive of the shrinkage results with some residual monomer left after polymerization. Polymerization of a two-solution bone cement in a constrained state resulted in pores developing with volumes predicted by the theory that they are the result of shrinkage. The results of this study show that shrinkage of bone cement under certain constrained conditions may result in the development of porosity at the implant-bone cement interface and elsewhere in the polymerizing cement mantle.

  4. Properties evaluation of silorane, low-shrinkage, non-flowable and flowable resin-based composites in dentistry.

    PubMed

    Maia, Rodrigo R; Reis, Rodrigo S; Moro, André F V; Perez, Cesar R; Pessôa, Bárbara M; Dias, Katia R H C

    2015-01-01

    Purpose. This study tested the null hypothesis that different classes of direct restorative dental materials: silorane-based resin, low-shrinkage and conventional (non-flowable and flowable) resin-based composite (RBC) do not differ from each other with regard to polymerization shrinkage, depth of cure or microhardness. Methods. 140 RBC samples were fabricated and tested by one calibrated operator. Polymerization shrinkage was measured using a gas pycnometer both before and immediately after curing with 36 J/cm(2) light energy density. Depth of cure was determined, using a penetrometer and the Knoop microhardness was tested from the top surface to a depth of 5 mm. Results. Considering polymerization shrinkage, the authors found significant differences (p < 0.05) between different materials: non-flowable RBCs showed lower values compared to flowable RBCs, with the silorane-based resin presenting the smallest shrinkage. The low shrinkage flowable composite performed similarly to non-flowable with significant statistical differences compared to the two other flowable RBCs. Regarding to depth of cure, low-shrinkage flowable RBC, were most effective compared to other groups. Microhardness was generally higher for the non-flowable vs. flowable RBCs (p < 0.05). However, the values for low-shrinkage flowable did not differ significantly from those of non-flowable, but were significantly higher than those of the other flowable RBCs. Clinical Significance. RBCs have undergone many modifications as they have evolved and represent the most relevant restorative materials in today's dental practice. This study of low-shrinkage RBCs, conventional RBCs (non-flowable and flowable) and silorane-based composite-by in vitro evaluation of volumetric shrinkage, depth of cure and microhardness-reveals that although filler content is an important determinant of polymerization shrinkage, it is not the only variable that affects properties of materials that were tested in this study.

  5. Microcirculatory Response In Vivo on Local Intraarterial Infusion of Autogenic Adipose-derived Stem Cells or Stromal Vascular Fraction.

    PubMed

    Wang, Wei Z

    2016-09-01

    Both adipose-derived stem cells (ASCs) and stromal vascular fraction (SVF) have been demonstrated to have regenerative properties with therapeutic potential for numerous diseases through local or topical applications. However, it is unclear whether ASC or SVF can be delivered systemically through an intra-arterial infusion. The purpose of this study was to examine the microcirculatory response in vivo on local intraarterial infusion of autogenic ASCs or SVF in a vascular pedicle isolated rat cremaster microcirculation model.

  6. Comparative results of autogenous ignition temperature measurements by ASTM G 72 and pressurized scanning calorimetry in gaseous oxygen

    NASA Technical Reports Server (NTRS)

    Bryan, C. J.; Lowrie, R.

    1986-01-01

    The autogenous ignition temperature of four materials was determined by ASTM (G 72) and pressurized differential scanning calorimetry at 0.68-, 3.4-, and 6.8-MPa oxygen pressure. All four materials were found to ignite at lower temperatures in the ASTM method. The four materials evaluated in this program were Neoprene, Vespel SP-21, Fluorel E-2160, and nylon 6/6.

  7. Success rate of implants placed in autogenous bone blocks versus allogenic bone blocks: A systematic literature review

    PubMed Central

    Motamedian, Saeed Reza; Khojaste, Moein; Khojasteh, Arash

    2016-01-01

    The aim of this study is to review and compare survival/success rate of dental implants inserted in autogenous and allogenic bone blocks (ALBs). A PubMed search was performed from January 1990 to June 2014 limited to English language and human studies. Studies that reported treatment outcome of implants inserted in augmented alveolar ridges with autogenous or ALBs were included. Primary search identified 470 studies. For autogenous bone block (ABB) 36 articles and for ALB 23 articles met the inclusion criteria. Evidence on implant survival/success rate of both techniques was limited to observational studies with relatively small sample sizes. Study design, treatment methods, follow-ups, defect location, and morphology varied among studies. The range of implant survival and success rates in ABB was from 73.8% to 100% and 72.8% to 100%, respectively. The corresponding numbers for ALB were 95.3–100% and 93.7–100%, respectively. A definite conclusion could not be reached. Future studies with long-term follow-ups are required to further elucidate this issue. PMID:27563613

  8. Reduced heart rate variability and vagal tone in anxiety: trait versus state, and the effects of autogenic training.

    PubMed

    Miu, Andrei C; Heilman, Renata M; Miclea, Mircea

    2009-01-28

    This study investigated heart rate variability (HRV) in healthy volunteers that were selected for extreme scores of trait anxiety (TA), during two opposite psychophysiological conditions of mental stress, and relaxation induced by autogenic training. R-R intervals, HF and LF powers, and LF/HF ratios were derived from short-term electrocardiographic recordings made during mental stress and relaxation by autogenic training, with respiratory rate and skin conductance being controlled for in all the analyses. The main finding was that high TA was associated with reduced R-R intervals and HF power across conditions. In comparison to mental stress, autogenic training increased HRV and facilitated the vagal control of the heart. There were no significant effects of TA or the psychophysiological conditions on LF power, or LF/HF ratio. These results support the view that TA, which is an important risk factor for anxiety disorders and predictor of cardiovascular morbidity and mortality, is associated with autonomic dysfunction that seems likely to play a pathogenetic role in the long term.

  9. The augmenting role of biofeedback: effects of autogenic, imagery and music training on physiological indices and athletic performance.

    PubMed

    Blumenstein, B; Bar-Eli, M; Tenenbaum, G

    1995-08-01

    In this study, three psychoregulative procedures of relaxation and excitation were provided in combination with biofeedback to examine their role on physiological and athletic performance variables. Thirty-nine college students were randomly assigned to three groups of psychoregulatory treatment (autogenic and imagery training, AT+IT; music and imagery training, M+IT; autogenic, music and imagery training, AT+M+IT), one placebo group and the control group. Imagery was related to a 100-m run. The treatment and control conditions lasted 13 sessions of 20 min each. During the first seven sessions, the subjects in the treatment groups underwent 10 min of relaxation followed by 10 min of excitation. During the last six sessions, similar treatment was provided accompanied by frontalis EMG biofeedback. Heart rate, the galvanic skin response, EMG and breathing frequency (fb) were recorded three times during each session. In addition, an athletic task (100-m run) was examined at the outset, after seven sessions (no biofeedback) and after an additional six sessions (with biofeedback). Biofeedback was found to have a significant augmenting effect on physiological components and athletic performance when accompanied by autogenic, imagery and music training. Soft music was found to be as beneficial as other relaxation techniques. The results are compared with similar studies applying mental techniques with biofeedback, and new directions of investigation in the psychophysiological domain are suggested.

  10. Facilitation of internal locus of control in adolescent alcoholics through a brief biofeedback-assisted autogenic relaxation training procedure.

    PubMed

    Sharp, C; Hurford, D P; Allison, J; Sparks, R; Cameron, B P

    1997-01-01

    The purpose of the study was to determine if autogenic relaxation training facilitated through biofeedback promotes an increase in internal levels of locus of control. The participants were residents of two Southwest Missouri alcohol treatment centers and ranged in age from 18 to 21 years. Treatment and control groups were compared on their responses on the Drinking Related Locus of Control Scale (DRIE) and fingertip temperature pre- and posttraining. The training was effective in teaching autogenic relaxation as demonstrated by increased fingertip temperature for the treatment group posttraining, while no differences were observed for the control group. Most importantly, the treatment group was not only significantly more internal in their locus of control after training but were also significantly more internal than the control group posttraining. Given that alcoholics are significantly more external in their locus of control than nonalcoholics, and that an internal locus of control implies an individual's belief that he or she has control and is responsible for his or her behavior, autogenic relaxation facilitated through biofeedback may be a very important component in therapeutic intervention for adolescent alcoholics.

  11. Crack propagation driven by crystal growth

    SciTech Connect

    A. Royne; Paul Meaking; A. Malthe-Sorenssen; B. Jamtveit; D. K. Dysthe

    2011-10-01

    Crystals that grow in confinement may exert a force on their surroundings and thereby drive crack propagation in rocks and other materials. We describe a model of crystal growth in an idealized crack geometry in which the crystal growth and crack propagation are coupled through the stress in the surrounding bulk solid. Subcritical crack propagation takes place during a transient period, which may be very long, during which the crack velocity is limited by the kinetics of crack propagation. When the crack is sufficiently large, the crack velocity becomes limited by the kinetics of crystal growth. The duration of the subcritical regime is determined by two non-dimensional parameters, which relate the kinetics of crack propagation and crystal growth to the supersaturation of the fluid and the elastic properties of the surrounding material.

  12. Corrosion fatigue crack propagation in metals

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.

    1990-01-01

    This review assesses fracture mechanics data and mechanistic models for corrosion fatigue crack propagation in structural alloys exposed to ambient temperature gases and electrolytes. Extensive stress intensity-crack growth rate data exist for ferrous, aluminum and nickel based alloys in a variety of environments. Interactive variables (viz., stress intensity range, mean stress, alloy composition and microstructure, loading frequency, temperature, gas pressure and electrode potential) strongly affect crack growth kinetics and complicate fatigue control. Mechanistic models to predict crack growth rates were formulated by coupling crack tip mechanics with occluded crack chemistry, and from both the hydrogen embrittlement and anodic dissolution/film rupture perspectives. Research is required to better define: (1) environmental effects near threshold and on crack closure; (2) damage tolerant life prediction codes and the validity of similitude; (3) the behavior of microcrack; (4) probes and improved models of crack tip damage; and (5) the cracking performance of advanced alloys and composites.

  13. Autogenic terraces and non-linear river incision rates under steady external forcing

    NASA Astrophysics Data System (ADS)

    Malatesta, Luca C.; Prancevic, Jeffrey P.; Avouac, Jean-Philippe

    2015-04-01

    Fluvial terraces are among the most commonly cited records of hydraulic changes and tectonic events, and researchers often use the timing of their abandonment to constrain regional climatic and tectonic forcings. However, it can be challenging to identify the cause of terrace abandonment, as the same first order signature results from multiple drivers: external forcings of tectonics and climate, and internal autogenic feedbacks. Misinterpretation of the origin of fluvial terraces carries important consequences, as they often are key evidences for geomorphological and tectonic studies. Using a numerical model we identify an autogenic mechanism in transport-limited rivers that produces accelerated incision rates and the abandonment of significant terraces under steady forcing conditions. We show that a 'bank-feedback' process controls the cross-sectional geometry of channel entrenchment through the rising cost of eroding higher banks. During a phase of incision under the forcing of regular discharges (e.g. bankfull floods), an incising alluvial river migrates in a floodplain bound by progressively higher banks. Consequently, the volume of sediment produced by a unit of lateral migration grows larger and eventually forms a talus that may persist for multiple flood events. The talus shields the toe of the bank and prevents lateral erosion while vertical erosion can continue unhindered. This bank-shielding mechanism becomes more effective as vertical erosion creates even higher banks, initiating a feedback that promotes dramatic vertical entrenchment and abandonment of wide terraces. We propose that such a 'bank-feedback' process also plays a large role in determining the source of bedload material by forcing the river to tap into deeper and older sedimentary strata. We compare the 'bank-feedback' mechanism with a well-studied case of the northern piedmont of the East Tian Shan. There, terrace ages documenting >200 m of Holocene river incision, record a fourfold

  14. Getter materials for cracking ammonia

    DOEpatents

    Boffito, Claudio; Baker, John D.

    1999-11-02

    A method is provided for cracking ammonia to produce hydrogen. The method includes the steps of passing ammonia over an ammonia-cracking catalyst which is an alloy including (1) alloys having the general formula Zr.sub.1-x Ti.sub.x M.sub.1 M.sub.2, wherein M.sub.1 and M.sub.2 are selected independently from the group consisting of Cr, Mn, Fe, Co, and Ni, and x is between about 0.0 and about 1.0 inclusive; and between about 20% and about 50% Al by weight. In another aspect, the method of the invention is used to provide methods for operating hydrogen-fueled internal combustion engines and hydrogen fuel cells. In still another aspect, the present invention provides a hydrogen-fueled internal combustion engine and a hydrogen fuel cell including the above-described ammonia-cracking catalyst.

  15. Significant reversibility of alcoholic brain shrinkage within 3 weeks of abstinence.

    PubMed

    Trabert, W; Betz, T; Niewald, M; Huber, G

    1995-08-01

    Chronic alcoholism is often associated with brain shrinkage or atrophy. During recent years, it has been demonstrated that this shrinkage is, at least in part, reversible when abstinence is maintained. There are different hypotheses concerning the mechanisms for this reversibility, but many questions are still open. Especially the time conditions for these reversible changes are subject of discussion. Twenty-eight male patients with severe alcohol dependence were investigated in a computed tomographic study at the beginning of abstinence and 3 weeks later. Planimetric evaluation of 5 selected slices revealed a significant decrease in liquor areas and an increase of brain volume. The densitometric analysis showed an increase in brain tissue density. In a multiple regression approach it was shown that the reversibility was mostly influenced by the age of the patients. Our results support neither the hypothesis of an increase in brain water as the most important principle for reversibility in alcoholic brain shrinkage nor the hypothesis of augmented dendritic growth. Other mechanisms like reduced (during chronic intoxication) and normalized (during abstinence) cerebral hemoperfusion have to be considered as possible mechanisms for the reversibility of alcoholic brain shrinkage.

  16. Differential brain shrinkage over 6 months shows limited association with cognitive practice.

    PubMed

    Raz, Naftali; Schmiedek, Florian; Rodrigue, Karen M; Kennedy, Kristen M; Lindenberger, Ulman; Lövdén, Martin

    2013-07-01

    The brain shrinks with age, but the timing of this process and the extent of its malleability are unclear. We measured changes in regional brain volumes in younger (age 20-31) and older (age 65-80) adults twice over a 6 month period, and examined the association between changes in volume, history of hypertension, and cognitive training. Between two MRI scans, 49 participants underwent intensive practice in three cognitive domains for 100 consecutive days, whereas 23 control group members performed no laboratory cognitive tasks. Regional volumes of seven brain structures were measured manually and adjusted for intracranial volume. We observed significant mean shrinkage in the lateral prefrontal cortex, the hippocampus, the caudate nucleus, and the cerebellum, but no reliable mean change of the prefrontal white matter, orbital-frontal cortex, and the primary visual cortex. Individual differences in change were reliable in all regions. History of hypertension was associated with greater cerebellar shrinkage. The cerebellum was the only region in which significantly reduced shrinkage was apparent in the experimental group after completion of cognitive training. Thus, in healthy adults, differential brain shrinkage can be observed in a narrow time window, vascular risk may aggravate it, and intensive cognitive activity may have a limited effect on it.

  17. Brain shrinkage in alcoholics is not caused by changes in hydration: a pathological study.

    PubMed

    Harper, C G; Kril, J J; Daly, J M

    1988-01-01

    Measurement of the water content of the cerebral white matter in 26 control and 24 alcoholic cases supports in vivo MRI studies and previous necropsy studies which appeared to show an increase in the water content in the alcoholic group. This negates the hypothesis that reversible brain shrinkage in alcoholics is caused by changes in the state of hydration.

  18. Urban shrinkage in Germany and the USA: a comparison of transformation patterns and local strategies.

    PubMed

    Wiechmann, Thorsten; Pallagst, Karina M

    2012-01-01

    Many American and European cities have to deal with demographic and economic trajectories leading to urban shrinkage. According to official data, 13% of urban regions in the US and 54% of those in the EU have lost population in recent years. However, the extent and spatial distribution of declining populations differ significantly between Europe and the US. In Germany, the situation is driven by falling birth rates and the effects of German reunification. In the US, shrinkage is basically related to long-term industrial transformation. But the challenges of shrinking cities seldom appeared on the agendas of politicians and urban planners until recently. This article provides a critical overview of the development paths and local strategies of four shrinking cities: Schwedt and Dresden in eastern Germany; Youngstown and Pittsburgh in the US. A typology of urban growth and shrinkage, from economic and demographic perspectives, enables four types of city to be differentiated and the differences between the US and eastern Germany to be discussed. The article suggests that a new transatlantic debate on policy and planning strategies for restructuring shrinking cities is needed to overcome the dominant growth orientation that in most cases intensifies the negative consequences of shrinkage.

  19. [Shrinkage In the Squared Multiple Correlation Coefficient and Unbiased Estimates of Treatment Effects Using Omega Squared.

    ERIC Educational Resources Information Center

    Dalton, Starrett

    The amount of variance accounted for by treatment can be estimated with omega squared or with the squared multiple correlation coefficient. Monte Carlo methods were employed to compare omega squared, the squared multiple correlation coefficient, and the squared multiple correlation coefficient to which a shrinkage formula had been applied, in…

  20. Shrinkage of bubbles and drops in the lattice Boltzmann equation method for nonideal gases

    NASA Astrophysics Data System (ADS)

    Zheng, Lin; Lee, Taehun; Guo, Zhaoli; Rumschitzki, David

    2014-03-01

    One characteristic of multiphase lattice Boltzmann equation (LBE) methods is that the interfacial region has a finite (i.e., noninfinitesimal) thickness known as a diffuse interface. In simulations of, e.g., bubble or drop dynamics, for problems involving nonideal gases, one frequently observes that the diffuse interface method produces a spontaneous, nonphysical shrinkage of the bubble or drop radius. In this paper, we analyze in detail a single-fluid two-phase model and use a LBE model for nonideal gases in order to explain this fundamental problem. For simplicity, we only investigate the static bubble or droplet problem. We find that the method indeed produces a density shift, bubble or droplet shrinkage, as well as a critical radius below which the bubble or droplet eventually vanishes. Assuming that the ratio between the interface thickness D and the initial bubble or droplet radius r0 is small, we analytically show the existence of this density shift, bubble or droplet radius shrinkage, and critical bubble or droplet survival radius. Numerical results confirm our analysis. We also consider droplets on a solid surface with different curvatures, contact angles, and initial droplet volumes. Numerical results show that the curvature, contact angle, and the initial droplet volume have an effect on this spontaneous shrinkage process, consistent with the survival criterion.

  1. Review of Environmentally Assisted Cracking

    NASA Astrophysics Data System (ADS)

    Sadananda, K.; Vasudevan, A. K.

    2011-02-01

    Many efforts have been made in the past by several researchers to arrive at some unifying principles governing the embrittlement phenomena. An inescapable conclusion reached by all these efforts was that the behavior is very complex. Hence, recognizing the complexity of material/environment behavior, we focus our attention here only in extracting some similarities in the experimental trends to arrive at some generic principles of behavior. Crack nucleation and growth are examined under static load in the presence of internal and external environments. Stress concentration, either pre-existing or in-situ generated, appears to be a requirement for embrittlement. A chemical stress concentration factor is defined for a given material/environment system as the ratio of failure stress with and without the damaging chemical environment. All factors that affect the buildup of the required stress concentration, such as planarity of slip, stacking fault energy, etc., also affect the stress-corrosion behavior. The chemical stress concentration factor is coupled with the mechanical stress concentration factor. In addition, generic features for all systems appear to be (a) an existence of a threshold stress as a function of concentration of the damaging environment and flow properties of the material, and (b) an existence of a limiting threshold as a function of concentration, indicative of a damage saturation for that environment. Kinetics of crack growth also depends on concentration and the mode of crack growth. In general, environment appears to enhance crack tip ductility on one side by the reduction of energy for dislocation nucleation and glide, and to reduce cohesive energy for cleavage, on the other. These two opposing factors are coupled to provide environmentally induced crack nucleation and growth. The relative ratio of these two opposing factors depends on concentration and flow properties, thereby affecting limiting thresholds. The limiting concentration or

  2. Taguchi design and flower pollination algorithm application to optimize the shrinkage of triaxial porcelain containing palm oil fuel ash

    NASA Astrophysics Data System (ADS)

    Zainudin, A.; Sia, C. K.; Ong, P.; Narong, O. L. C.; Nor, N. H. M.

    2017-01-01

    In the preparation of triaxial porcelain from Palm Oil Fuel Ash (POFA), a new parameter variable must be determined. The parameters involved are the particle size of POFA, percentage of POFA in triaxial porcelain composition, moulding pressure, sintering temperature and soaking time. Meanwhile, the shrinkage is the dependent variable. The optimization process was investigated using a hybrid Taguchi design and flower pollination algorithm (FPA). The interaction model of shrinkage was derived from regression analysis and found that the shrinkage is highly dependent on the sintering temperature followed by POFA composition, moulding pressure, POFA particle size and soaking time. The interaction between sintering temperature and soaking time highly affects the shrinkage. From the FPA process, targeted shrinkage approaching zero values were predicted for 142 μm particle sizes of POFA, 22.5 wt% of POFA, 3.4 tonne moulding pressure, 948.5 °C sintering temperature and 264 minutes soaking time.

  3. Experimental evaluation and simulation of volumetric shrinkage and warpage on polymeric composite reinforced with short natural fibers

    NASA Astrophysics Data System (ADS)

    Santos, Jonnathan D.; Fajardo, Jorge I.; Cuji, Alvaro R.; García, Jaime A.; Garzón, Luis E.; López, Luis M.

    2015-09-01

    A polymeric natural fiber-reinforced composite is developed by extrusion and injection molding process. The shrinkage and warpage of high-density polyethylene reinforced with short natural fibers of Guadua angustifolia Kunth are analyzed by experimental measurements and computer simulations. Autodesk Moldflow® and Solid Works® are employed to simulate both volumetric shrinkage and warpage of injected parts at different configurations: 0 wt.%, 20 wt.%, 30 wt.% and 40 wt.% reinforcing on shrinkage and warpage behavior of polymer composite. Become evident the restrictive effect of reinforcing on the volumetric shrinkage and warpage of injected parts. The results indicate that volumetric shrinkage of natural composite is reduced up to 58% with fiber increasing, whereas the warpage shows a reduction form 79% to 86% with major fiber content. These results suggest that it is a highly beneficial use of natural fibers to improve the assembly properties of polymeric natural fiber-reinforced composites.

  4. Microstructural evolution and macroscopic shrinkage in the presence of density gradients and agglomeration

    NASA Astrophysics Data System (ADS)

    Lu, Peizhen

    X-ray computed tomography (CT) can characterize internal density gradients. An in-situ laser dilatometry has been constructed to track dimensional change at different positions of a sample during binder removal and sintering. This combination of tools not only allows us to better understand how microscopic change affects macroscopic dimensions, but also provides guidance for a variety of ceramic processes. Non-uniform agglomerate packing and deformation provide density gradients which drive binder migration during binder removal. Simultaneously, density undergoes a slight decrease accompanied by a 1.0% loss in dimensional tolerance. This and CT difference images suggest that capillary forces generated during binder melting can change the density distribution. During sintering, nonuniformities present in the green state persist into the fired state and become exaggerated. Regions of different initial density can occupy different stages sintering. At ˜88% sintered density, CT clearly showed that open porosity follows the distribution of low density areas. Mercury porosimetry detected three distinct levels of porosity. Microstructural examination correlated the porosity level with the coordination of (i) two to three or (ii) multiple grains around pores. Microstructural packing controls both the observed macroscopic expansion at T ≤ 1000°C and the onset of shrinkage. Neck formation initiates during expansion and not exclusively during shrinkage. Inter- and intra-agglomerate expansion/shrinkage proceed simultaneously but the effective 'transmission' of particle-level behavior to the macroscopic level appears to be controlled by the initial agglomerate bonding and internal agglomerate densities. Discrete element modeling provides corroborating evidence regarding the importance of compact continuity. Following the expansion-shrinkage transition, the higher the zone density the faster the initial shrinkage. The 25% RH sample shrank more rapidly than the same zone in

  5. Slow Crack Growth of Germanium

    NASA Technical Reports Server (NTRS)

    Salem, Jon

    2016-01-01

    The fracture toughness and slow crack growth parameters of germanium supplied as single crystal beams and coarse grain disks were measured. Although germanium is anisotropic (A=1.7), it is not as anisotropic as SiC, NiAl, or Cu, as evidence by consistent fracture toughness on the 100, 110, and 111 planes. Germanium does not exhibit significant slow crack growth in distilled water. (n=100). Practical values for engineering design are a fracture toughness of 0.7 MPam and a Weibull modulus of m=6+/-2. For well ground and reasonable handled coupons, fracture strength should be greater than 30 MPa.

  6. Nonlinear structural crack growth monitoring

    DOEpatents

    Welch, Donald E.; Hively, Lee M.; Holdaway, Ray F.

    2002-01-01

    A method and apparatus are provided for the detection, through nonlinear manipulation of data, of an indicator of imminent failure due to crack growth in structural elements. The method is a process of determining energy consumption due to crack growth and correlating the energy consumption with physical phenomena indicative of a failure event. The apparatus includes sensors for sensing physical data factors, processors or the like for computing a relationship between the physical data factors and phenomena indicative of the failure event, and apparatus for providing notification of the characteristics and extent of such phenomena.

  7. Crack growth resistance in nuclear graphites

    NASA Astrophysics Data System (ADS)

    Ouagne, Pierre; Neighbour, Gareth B.; McEnaney, Brian

    2002-05-01

    Crack growth resistance curves for the non-linear fracture parameters KR, JR and R were measured for unirradiated PGA and IM1-24 graphites that are used as moderators in British Magnox and AGR nuclear reactors respectively. All the curves show an initial rising part, followed by a plateau region where the measured parameter is independent of crack length. JR and R decreased at large crack lengths. The initial rising curves were attributed to development of crack bridges in the wake of the crack front, while, in the plateau region, the crack bridging zone and the frontal process zone, ahead of the crack tip, reached steady state values. The decreases at large crack lengths were attributed to interaction of the frontal zone with the specimen end face. Microscopical evidence for graphite fragments acting as crack bridges showed that they were much smaller than filler particles, indicating that the graphite fragments are broken down during crack propagation. There was also evidence for friction points in the crack wake zone and shear cracking of some larger fragments. Inspection of KR curves showed that crack bridging contributed ~0.4 MPa m0.5 to the fracture toughness of the graphites. An analysis of JR and R curves showed that the development of the crack bridging zone in the rising part of the curves contributed ~20% to the total work of fracture. Energies absorbed during development of crack bridges and steady state crack propagation were greater for PGA than for IM1-24 graphite. These differences reflect the greater extent of irreversible processes occurring during cracking in the coarser microtexture of PGA graphite.

  8. Specimen size effect in the volumetric shrinkage of cancellous bone measured at two levels of dehydration.

    PubMed

    Lievers, W Brent; Lee, Victoria; Arsenault, Simon M; Waldman, Stephen D; Pilkey, A Keith

    2007-01-01

    Water is commonly removed from bone to study its effect on mechanical behaviour; however, dehydration also alters the bone structure. To make matters worse, measuring structural changes in cancellous bone is complicated by a number of factors. Therefore, the goals of this study were to address these issues by (1) comparing Archimedes' method and a helium pycnometer as methods for measuring cancellous bone volume; (2) measuring the apparent dimensional and volumetric tissue shrinkage of cancellous bone at two levels of dehydration; and, (3) identifying whether a size effect exists in cancellous bone shrinkage. Cylindrical specimens (3, 5 and 8.3 mm diameters) of cancellous bone were taken from the distal bovine femur. The apparent dimensions of each cylindrical specimen were measured in a fully hydrated state (HYD), after drying at room temperature (AIR), and after oven drying at 105 degrees C (OVEN). Tissue volume measurements for those three hydration states were obtained using both a helium pycnometer and Archimedes' method. Aluminium foams, which mimic the cancellous structure, were used as controls. The results suggest that the helium pycnometer and Archimedes' method yield identical results in the HYD and AIR states, but that Archimedes' method under-predicts the nominal OVEN volume by incorporating the collagen-apatite porosity. A distinct size effect on volumetric shrinkage is observed (p<0.025) using the pycnometer in both AIR and OVEN states. Apparent dimensional shrinkage (2% and 7%) at the two dehydration levels is much smaller than the measured volumetric tissue shrinkage (16% and 29%), which results in a reduced dehydrated bone volume fraction.

  9. The role of autogenic inhibition in the reduction of muscle splinting

    PubMed Central

    Miller, Herbert

    1982-01-01

    Muscle ‘splinting’ (acute hypertonicity) is the clinical entity commonly featured as a result of somatic or visceral trauma. One of the implicit objectives of manipulative therapy is to stretch hypertonic muscles. The mechanical parameters of the manipulative thrust are reviewed in relation to the physiology of the muscle afferents which are activated by changes in length, tension and momentum. During muscular contraction, autogenic inhibition is initiated in parallel (with the motor excitation), via the interneurons that are activated by the Golgi tendon organs. It appears that when an excessive force is applied to or exerted by a muscle at varying lengths (extensions), the Golgi tendon organ inhibition regulates not only the frequency of discharge, but also the range of firing of the motoneurons. This relaxation (the inhibition of gamma, as well as alpha motoneurons) is one of the desired end results of manual therapy in most conditions. The role of other muscle afferents (groups Ia and II) and the “gamma loop” are also discussed in relation to the muscle ‘splinting’ phenomenon.

  10. Cephalic Arch Stenosis in Autogenous Haemodialysis Fistulas: Treatment With the Viabahn Stent-Graft

    SciTech Connect

    Shawyer, Andrew; Fotiadis, Nicos I.; Namagondlu, Girish; Iyer, Arun; Blunden, Mark Raftery, Martin Yaqoob, Magdi

    2013-02-15

    Cephalic arch stenosis (CAS) is an important and common cause of dysfunction in autogenous haemodialysis fistulas that requires multiple reinterventions and aggressive surveillance. We evaluated the safety and efficacy of the Viabahn stent-graft for the management of CAS. Between April 2005 and October 2011, 11 consecutive patients [four men and seven women (mean age 56.7 years)] with CAS and dysfunctional fistulas were treated with insertion of 11 Viabahn stent-grafts. Six stent-grafts were inserted due to residual stenosis after angioplasty and five for fistuloplasty-induced rupture. No patient was lost to follow-up. The technical and clinical success rate was 100 %. Primary access patency rates were 81.8 % [95 % confidence interval (CI) 0.482-0.977] at 6 months and 72.7 % (95 % CI 0.390-0.939) at 12 months. Secondary access patency rates were 90.9 % at 6 months (95 % CI 0.587-0.997). There were no procedure-related complications. Mean follow-up was 543.8 days (range 156-2,282). The use of the Viabahn stent-graft in the management of CAS is technically feasible and, in this small series, showed patency rates that compare favorably with historical data of angioplasty and bare stents.

  11. Biological and physical properties of autogenous vascularized fibular grafts in dogs

    SciTech Connect

    Goldberg, V.M.; Stevenson, S.; Shaffer, J.W.; Davy, D.; Klein, L.; Zika, J.; Field, G. )

    1990-07-01

    The biological and biomechanical properties of normal fibulae, fibulae that had had a sham operation, and both vascularized and non-vascularized autogenous grafts were studied in dogs at three months after the operation. The study was designed to quantify and correlate changes in these properties in orthotopic, stably fixed, weight-bearing grafts and to provide a baseline for additional studies of allografts. The grafts were eight centimeters long and internally fixed. The mechanical properties of the grafts were studied by torsional testing. Metabolic turnover of the grafts was evaluated by preoperative labeling of the dogs with 3H-tetracycline for resorption of bone mineral and with 3H-proline for turnover of collagen. Cortical bone area and porosity were measured. Postoperative formation of bone was evaluated by sequential labeling with fluorochrome. The vascularized grafts resembled the fibulae that had had a sham operation and those that had not had an operation with regard to the total number of osteons and the remodeling process, as measured both morphometrically and metabolically. The vascularized grafts were stronger and stiffer than the non-vascularized grafts and were not different from the bones that had had a sham operation. In contrast, the non-vascularized grafts were smaller, weaker, less stiff, and more porotic, had fewer osteons, and demonstrated increased turnover and resorption compared with the vascularized grafts, the bones that had had a sham operation, and the bones that had not been operated on.

  12. Autogenic-feedback training improves pilot performance during emergency flying conditions

    NASA Technical Reports Server (NTRS)

    Kellar, Michael A.; Folen, Raymond A.; Cowings, Patricia S.; Toscano, William B.; Hisert, Glen L.

    1993-01-01

    Studies have shown that autonomous mode behavior is one cause of aircraft fatalities due to pilot error. In such cases, the pilot is in a high state of psychological and physiological arousal and tends to focus on one problem, while ignoring more critical information. The effect of training in physiological self-recognition and regulation, as a means of improving crew cockpit performance was examined. Seventeen pilots were assigned to the treatment and control groups matched for accumulated flight hours. The treatment group comprised four pilots of HC-130 Hercules aircraft and four HH-65 Dolphin helicopter pilots; the control group comprised three pilots of HC-130's and six Dolphin helicopter pilots. During an initial flight physiological data were recorded for each crewmember and individual crew performance and rated by an instructor pilot. Eight crewmembers were then taught to regulate their own physiological response levels using Autogenic-Feedback Training (AFT). The remaining subjects received no training. During a second flight, treatment subjects showed significant improvement in performance, while controls did not improve. The results indicate that AFT management of high states of physiological arousal may improve pilot performance during emergency flying conditions.

  13. Autogenic-feedback training: A potential treatment for post-flight orthostatic intolerance in aerospace crews

    NASA Technical Reports Server (NTRS)

    Cowings, Patricia S.; Toscano, William B.; Miller, Neil E.; Pickering, Thomas G.; Shapiro, David

    1993-01-01

    Postflight orthostatic intolerance was identified as a serious biomedical problem associated with long duration exposure to microgravity in space. High priority was given to the development of countermeasures for this disorder which are both effective and practical. A considerable body of clinical research demonstrated that people can be taught to increase their own blood pressure voluntarily and that this is an effective treatment for chronic orthostatic intolerance in paralyzed patients. The present pilot study was designed to examine the feasibility of adding training in control of blood pressure to an existing preflight training program designed to facilitate astronaut adaptation to microgravity. Using an operant conditioning procedure, Autogenic-Feedback Training (AFT), three men and two women participated in four to nine (15-30 training sessions). At the end of training, the average increase in systolic and diastolic pressure, as well as mean arterial pressures that the subjects made, ranged between 20 and 5O mmHg under both supine and 45 deg head-up tilt conditions. These findings suggest that AFT may be a useful alternative treatment or supplement to existing approaches for preventing postflight orthostatic intolerance. Further, the use of operant conditioning methods for training cardiovascular responses may contribute to the general understanding of the mechanisms of orthostatic intolerance.

  14. Autogenic-feedback training improves pilot performance during emergency flying conditions

    NASA Technical Reports Server (NTRS)

    Kellar, Michael A.; Folen, Raymond A.; Cowings, Patricia S.; Toscano, William B.; Hisert, Glen L.

    1994-01-01

    Studies have shown that autonomous mode behavior is one cause of aircraft fatalities due to pilot error. In such cases, the pilot is in a high state of psychological and physiological arousal and tends to focus on one problem, while ignoring more critical information. This study examined the effect of training in physiological self-recognition and regulation, as a means of improving crew cockpit performance. Seventeen pilots were assigned to the treatment and control groups matched for accumulated flight hours. The treatment group comprised three pilots of HC-130 Hercules aircraft and four HH-65 Dolphin helicopter pilots; the control group comprised three pilots of HC-130's and six Dolphin helicopter pilots. During an initial flight, physiological data were recorded for each crew member and individual crew performance was rated by an instructor pilot. Eight crewmembers were then taught to regulate their own physiological response levels using Autogenic-Feedback Training (AFT). The remaining subjects received no training. During a second flight, treatment subjects showed significant improvement in performance, while controls did not improve. The results indicate that AFT management of high states of physiological arousal may improve pilot performance during emergency flying conditions.

  15. Silicate minerals for CO2 scavenging from biogas in Autogenerative High Pressure Digestion.

    PubMed

    Lindeboom, Ralph E F; Ferrer, Ivet; Weijma, Jan; van Lier, Jules B

    2013-07-01

    Autogenerative High Pressure Digestion (AHPD) is a novel concept that integrates gas upgrading with anaerobic digestion by selective dissolution of CO2 at elevated biogas pressure. However, accumulation of CO2 and fatty acids after anaerobic digestion of glucose resulted in pH 3-5, which is incompatible with the commonly applied high-rate methanogenic processes. Therefore, we studied the use of wollastonite, olivine and anorthosite, with measured composition of CaSi1.05O3.4, Mg2Fe0.2Ni0.01Si1.2O5.3 and Na0.7Ca1K0.1Mg0.1Fe0.15Al3.1Si4O24, respectively, to scavenge CO2 during batch AHPD of glucose. Depending on the glucose to mineral ratio the pH increased to 6.0-7.5. Experiments with wollastonite showed that Ca(2+)-leaching was caused by volatile fatty acid (VFA) production during glucose digestion. At 1, 3 and 9 bar, the CH4 content reached 74%, 86% and 88%, respectively, indicating CO2 scavenging. Fixation of produced CO2 by CaCO3 precipitation in the sludge was confirmed by Fourier Transferred-InfraRed, Combined Field emission Scanning Electron Microscopy-Energy-dispersive X-ray spectroscopy and Thermogravimetric Analysis-Mass Spectroscopy.

  16. Autogenic EMG-Controlled Functional Electrical Stimulation for Ankle Dorsiflexion Control

    PubMed Central

    Yeom, Hojun; Chang, Young-Hui

    2010-01-01

    Our objectives were to develop and test a new system for the potential for stable, real-time cancellation of residual stimulation artefacts (RSA) using surface electrode autogenic electromyography-controlled functional electrical stimulator (aEMGcFES). This type of closed-loop FES could be used to provide more natural, continuous control of lower extremity paretic muscles. We built upon work that has been done in the field of FES with one major technological innovation, an adaptive Gram-Schmidt filtering algorithm, which allowed us to digitally cancel RSA in real-time. This filtering algorithm resulted in a stable real-time estimation of the volitional intent of the stimulated muscle, which then acted as the direct signal for continuously controlling homonymous muscle stimulation. As a first step toward clinical application, we tested the viability of our aEMGcFES system to continuously control ankle dorsiflexion in a healthy subject. Our results indicate positively that an aEMGcFES device with adaptive filtering can respond proportionally to voluntary EMG and activate forceful movements to assist dorsiflexion during controlled isometric activation at the ankle. We also verified that normal ankle joint range of movement could be maintained while using the aEMGcFES system. We suggest that real-time cancellation of both primary and RSA is possible with surface electrode aEMGcFES in healthy subjects and shows promising potential for future clinical application to gait pathologies such as drop foot related to hemiparetic stroke. PMID:20713086

  17. Autogenic-feedback training: a potential treatment for orthostatic intolerance in aerospace crews.

    PubMed

    Cowings, P S; Toscano, W B; Miller, N E; Pickering, T G; Shapiro, D; Stevenson, J; Maloney, S; Knapp, J

    1994-06-01

    Postflight orthostatic intolerance has been identified as a serious biomedical problem associated with long-duration exposure to microgravity in space. High priority has been given to the development of countermeasures for this disorder that are both effective and practical. A considerable body of clinical research has demonstrated that people can be taught to increase their own blood pressure voluntarily, and that this is an effective treatment for chronic orthostatic intolerance in paralyzed patients. The current pilot study was designed to examine the feasibility of adding training in control of blood pressure to an existing preflight training program designed to facilitate astronaut adaptation to microgravity. Using an operant conditioning procedure, autogenic-feedback training (AFT), three men and two women participated in four to nine training (15-30-minute) sessions. At the end of training, the average increase in systolic and diastolic pressure, as well as mean arterial pressures, that the subjects made ranged between 20 and 50 mm Hg under both supine and 45 degrees head-up tilt conditions. These findings indicate that AFT may be a useful alternative treatment or supplement to existing approaches for preventing postflight orthostatic intolerance. Furthermore, the use of operant conditioning methods for training cardiovascular responses may contribute to the general understanding of the mechanisms of orthostatic intolerance.

  18. A Novel Albumin-Based Tissue Scaffold for Autogenic Tissue Engineering Applications

    NASA Astrophysics Data System (ADS)

    Li, Pei-Shan; -Liang Lee, I.; Yu, Wei-Lin; Sun, Jui-Sheng; Jane, Wann-Neng; Shen, Hsin-Hsin

    2014-07-01

    Tissue scaffolds provide a framework for living tissue regeneration. However, traditional tissue scaffolds are exogenous, composed of metals, ceramics, polymers, and animal tissues, and have a defined biocompatibility and application. This study presents a new method for obtaining a tissue scaffold from blood albumin, the major protein in mammalian blood. Human, bovine, and porcine albumin was polymerised into albumin polymers by microbial transglutaminase and was then cast by freeze-drying-based moulding to form albumin tissue scaffolds. Scanning electron microscopy and material testing analyses revealed that the albumin tissue scaffold possesses an extremely porous structure, moderate mechanical strength, and resilience. Using a culture of human mesenchymal stem cells (MSCs) as a model, we showed that MSCs can be seeded and grown in the albumin tissue scaffold. Furthermore, the albumin tissue scaffold can support the long-term osteogenic differentiation of MSCs. These results show that the albumin tissue scaffold exhibits favourable material properties and good compatibility with cells. We propose that this novel tissue scaffold can satisfy essential needs in tissue engineering as a general-purpose substrate. The use of this scaffold could lead to the development of new methods of artificial fabrication of autogenic tissue substitutes.

  19. Redox responsive albumin autogenic nanoparticles for the delivery of cancer drugs.

    PubMed

    Thirupathi Kumara Raja, S; Prakash, T; Gnanamani, A

    2017-04-01

    The present study explores preparation and characterization of redox sensitive albumin autogenic nanoparticles (ANPs) for drug delivery applications. Human serum albumin nanoparticles are prepared by desolvation method. The particles are stabilized through self-crosslinking and no external stabilizers are involved in the preparation. ANPs are then subjected to Camptothecin (CPT) drug loading. Experiments on in vitro and in vivo release profile, cytotoxic and cytocompatability, hemocompatability, blood clearance, tracking and bio imaging are studied in detail. The redox sensitive and drug release properties of ANPs studied in the presence of glutathione. Results on the physical, chemical and instrumental characterization warrant the property of the nanoparticles. ANPs obtained in the present study is biocompatible, biodegradable, effectively entangle the chosen drug, release the drug in the controlled manner, sensitive to reducing environment, nil toxicity and appreciable uptake by cells. In the current scenario on the requirement of a drug carrier with redox sensitive property to encounter cancer cells, the results of the present study on albumin nanoparticles with redox sensitivity is smart and pave the way in the cancer therapeutics.

  20. Influence of autogenous seeding on densification and microstructure in processing of γ-alumina nanopowders

    NASA Astrophysics Data System (ADS)

    Khodabakhshi, F.; Maleksaeedi, S.; Paydar, M. H.; Saadat, S.

    2011-01-01

    The effect of α-Al2O3 seeds and MgO on the densification behavior and microstructure of the nanocrystalline γ-Al2O3 powder was investigated. The required α-Al2O3 seeds were produced by 'autogenous seeding' where the seeds were obtained by calcination of the initial nanosized γ-Al2O3 powders above its transformation temperature and incorporated into γ-Al2O3 matrix. The seeds were characterized by means of laser particle size analyzer, X-ray diffraction, and Brunauer-Emmett-Teller surface analyzer. The simultaneous influence of α-Al2O3 seeds and MgO on γ-Al2O3 behavior was evaluated by differential thermal analysis, densitometry, and electron microscopy. The results showed that simultaneous presence of MgO and seeds in γ-Al2O3 matrix has a great impact on densification and microstructural evolution. The main role of MgO and the seeds are densification enhancement and grain refinement, respectively. The grain morphology is more equiaxed and desirably finer by using smaller seeds prepared using shorter calcination times.

  1. Histological evaluation of the influence of magnetic field application in autogenous bone grafts in rats

    PubMed Central

    Puricelli, Edela; Dutra, Nardier B; Ponzoni, Deise

    2009-01-01

    Background Bone grafts are widely used in oral and maxillofacial reconstruction. The influence of electromagnetic fields and magnets on the endogenous stimulation of target tissues has been investigated. This work aimed to assess the quality of bone healing in surgical cavities filled with autogenous bone grafts, under the influence of a permanent magnetic field produced by in vivo buried devices. Methods Metal devices consisting of commercially pure martensitic stainless steel washers and titanium screws were employed. Thirty male Wistar rats were divided into 3 experimental and 3 control groups. A surgical bone cavity was produced on the right femur, and a bone graft was collected and placed in each hole. Two metallic washers, magnetized in the experimental group but not in the control group, were attached on the borders of the cavity. Results The animals were sacrificed on postoperative days 15, 45 and 60. The histological analysis of control and experimental samples showed adequate integration of the bone grafts, with intense bone neoformation. On days 45 and 60, a continued influence of the magnetic field on the surgical cavity and on the bone graft was observed in samples from the experimental group. Conclusion The results showed intense bone neoformation in the experimental group as compared to control animals. The intense extra-cortical bone neoformation observed suggests that the osteoconductor condition of the graft may be more susceptible to stimulation, when submitted to a magnetic field. PMID:19134221

  2. Relaxation and health-related quality of life in multiple sclerosis: the example of autogenic training.

    PubMed

    Sutherland, Georgina; Andersen, Mark B; Morris, Tony

    2005-06-01

    This study was a pilot project to explore the effect of an autogenic training program (AT; a relaxation intervention) on the health-related quality of life (HRQOL) and well-being for people with multiple sclerosis. Participants either met weekly for sessions in AT for 10 weeks (n = 11) or were assigned to the control group (n = 11). The AT group was also asked to practice the technique daily at home. Scales designed to measure HRQOL and aspects of well-being (mood and depressed affect) were taken preintervention and at week 8 of the 10-week program. ANCOVAs using a measure of social support and pretest scores as covariates revealed that at the posttest the AT group reported more energy and vigor than the control group and were less limited in their roles due to physical and emotional problems. Future research should involve studies conducted over an extended period, together with sufficiently sized samples to explore the effect of frequency of practice of relaxation training on HRQOL and well-being for people with multiple sclerosis.

  3. Autogenic EMG-controlled functional electrical stimulation for ankle dorsiflexion control.

    PubMed

    Yeom, Hojun; Chang, Young-Hui

    2010-10-30

    Our objectives were to develop and test a new system for the potential for stable, real-time cancellation of residual stimulation artefacts (RSA) using surface electrode autogenic electromyography-controlled functional electrical stimulator (aEMGcFES). This type of closed-loop FES could be used to provide more natural, continuous control of lower extremity paretic muscles. We built upon work that has been done in the field of FES with one major technological innovation, an adaptive Gram-Schmidt filtering algorithm, which allowed us to digitally cancel RSA in real-time. This filtering algorithm resulted in a stable real-time estimation of the volitional intent of the stimulated muscle, which then acted as the direct signal for continuously controlling homonymous muscle stimulation. As a first step toward clinical application, we tested the viability of our aEMGcFES system to continuously control ankle dorsiflexion in a healthy subject. Our results indicate positively that an aEMGcFES device with adaptive filtering can respond proportionally to voluntary EMG and activate forceful movements to assist dorsiflexion during controlled isometric activation at the ankle. We also verified that normal ankle joint range of movement could be maintained while using the aEMGcFES system. We suggest that real-time cancellation of both primary and RSA is possible with surface electrode aEMGcFES in healthy subjects and shows promising potential for future clinical application to gait pathologies such as drop foot related to hemiparetic stroke.

  4. Epoxidation of 1-butene-3-ol over titanium silicalite TS-2 catalyst under autogenic pressure.

    PubMed

    Wróblewska, Agnieszka; Wajzberg, Joanna; Fajdek, Anna; Milchert, Eugeniusz

    2009-04-30

    Epoxidation of 1-butene-3-ol (1B3O) with 30 wt% hydrogen peroxide over TS-2 catalyst has been studied with methanol as a solvent and at elevated pressure (autogenic). The influence of temperature in the range of 20-120 degrees C, the molar ratio of 1B3O/H(2)O(2) 1:1-5:1, methanol concentration 5-90 wt%, TS-2 catalyst concentration 0.1-5.0 wt% and the reaction time 0.5-5.0 h have been investigated. The process was described by the following functions: the selectivity of transformation to 1,2-epoxybutane-3-ol (1,2EB3) in relation to 1B3O consumed, the selectivity of transformation to organic compounds in relation to H(2)O(2) consumed and the conversions of 1B3O and hydrogen peroxide. The major product of epoxidation is 1,2EB3, a compound with many applications.

  5. A novel albumin-based tissue scaffold for autogenic tissue engineering applications.

    PubMed

    Li, Pei-Shan; Lee, I-Liang; Yu, Wei-Lin; Sun, Jui-Sheng; Jane, Wann-Neng; Shen, Hsin-Hsin

    2014-07-18

    Tissue scaffolds provide a framework for living tissue regeneration. However, traditional tissue scaffolds are exogenous, composed of metals, ceramics, polymers, and animal tissues, and have a defined biocompatibility and application. This study presents a new method for obtaining a tissue scaffold from blood albumin, the major protein in mammalian blood. Human, bovine, and porcine albumin was polymerised into albumin polymers by microbial transglutaminase and was then cast by freeze-drying-based moulding to form albumin tissue scaffolds. Scanning electron microscopy and material testing analyses revealed that the albumin tissue scaffold possesses an extremely porous structure, moderate mechanical strength, and resilience. Using a culture of human mesenchymal stem cells (MSCs) as a model, we showed that MSCs can be seeded and grown in the albumin tissue scaffold. Furthermore, the albumin tissue scaffold can support the long-term osteogenic differentiation of MSCs. These results show that the albumin tissue scaffold exhibits favourable material properties and good compatibility with cells. We propose that this novel tissue scaffold can satisfy essential needs in tissue engineering as a general-purpose substrate. The use of this scaffold could lead to the development of new methods of artificial fabrication of autogenic tissue substitutes.

  6. Autogenic Feedback Training Exercise and pilot performance: enhanced functioning under search-and-rescue flying conditions.

    PubMed

    Cowings, P S; Kellar, M A; Folen, R A; Toscano, W B; Burge, J D

    2001-01-01

    Studies have shown that autonomous mode behavior is one cause of aircraft fatalities due to pilot error. In such cases, the pilot is in a high state of psychological and physiological arousal and tends to focus on one problem, while ignoring more critical information. This study examined the effect of training in physiological self-recognition and regulation, as a means of improving crew cockpit performance. Seventeen pilots were assigned to the treatment and control groups matched for accumulated flight hours. The treatment group contained 4 pilots from HC-130 Hercules aircraft and 4 HH-65 Dolphin helicopter pilots; the control group contained 3 pilots of HC-130s and 6 helicopter pilots. During an initial flight, physiological data were recorded on each crewmember and an instructor pilot rated individual crew performance. Eight crewmembers were then taught to regulate their own physiological response levels using Autogenic-Feedback Training Exercise (AFTE). The remaining participants received no training. During a second flight, treatment participants showed significant improvement in performance (rated by the same instructor pilot as in pretests) while controls did not improve. The results indicate that AFTE management of high states of physiological arousal may improve pilot performance during emergency flying conditions.

  7. A Novel Albumin-Based Tissue Scaffold for Autogenic Tissue Engineering Applications

    PubMed Central

    Li, Pei-Shan; -Liang Lee, I.; Yu, Wei-Lin; Sun, Jui-Sheng; Jane, Wann-Neng; Shen, Hsin-Hsin

    2014-01-01

    Tissue scaffolds provide a framework for living tissue regeneration. However, traditional tissue scaffolds are exogenous, composed of metals, ceramics, polymers, and animal tissues, and have a defined biocompatibility and application. This study presents a new method for obtaining a tissue scaffold from blood albumin, the major protein in mammalian blood. Human, bovine, and porcine albumin was polymerised into albumin polymers by microbial transglutaminase and was then cast by freeze-drying-based moulding to form albumin tissue scaffolds. Scanning electron microscopy and material testing analyses revealed that the albumin tissue scaffold possesses an extremely porous structure, moderate mechanical strength, and resilience. Using a culture of human mesenchymal stem cells (MSCs) as a model, we showed that MSCs can be seeded and grown in the albumin tissue scaffold. Furthermore, the albumin tissue scaffold can support the long-term osteogenic differentiation of MSCs. These results show that the albumin tissue scaffold exhibits favourable material properties and good compatibility with cells. We propose that this novel tissue scaffold can satisfy essential needs in tissue engineering as a general-purpose substrate. The use of this scaffold could lead to the development of new methods of artificial fabrication of autogenic tissue substitutes. PMID:25034369

  8. An autogeneic feeder cell system that efficiently supports growth of undifferentiated human embryonic stem cells.

    PubMed

    Stojkovic, Petra; Lako, Majlinda; Stewart, Rebecca; Przyborski, Stefan; Armstrong, Lyle; Evans, Jerome; Murdoch, Alison; Strachan, Tom; Stojkovic, Miodrag

    2005-03-01

    Human embryonic stem cells (hESCs) have great potential as a source of cells for therapeutic uses, but their culture requires the support of mouse or human cells, either directly as a feeder cell layer or indirectly as a source of conditioned medium in feeder-free culture systems. Unfortunately, the risks of cross-transfer of pathogens from xenogeneic or allogeneic feeders or cell by-products limit their medical applications. In addition, not all human feeders support the growth of hESCs equally well, and ethical concerns have been raised regarding the derivation of feeder cells from aborted human fetuses. We report here the culture of hESCs on a novel feeder cell system, comprising fibroblast-like cells derived from the spontaneous differentiation of hESCs. Isogenicity of the hESCs and hESC-derived fibroblasts was confirmed by micro satellite analysis. The nature of the hESC-derived fibroblasts was identified by the expression of specific markers. This feeder system permits continuous growth of undifferentiated and pluripotent hESCs, as demonstrated by the expression of specific hESC markers, by the formation of teratomas after injection of hESCs into severely combined immunodeficient mice, and by in vitro differentiation of hESCs into differentiated cells of ectodermal, endodermal, and mesodermal origin. Feeder cells derived from hESCs offers a potentially more secure autogeneic and genotypically homogenous system for the growth of undifferentiated hESCs.

  9. Autogenic-Feedback Training: A Potential Treatment for Orthostatic Intolerance in Aerospace Crews

    NASA Technical Reports Server (NTRS)

    Cowings, P. S.; Toscano, W. B.; Miller, N. E.; Pickering, T. G.; Shapiro, D.; Stevenson, J.; Maloney, S.; Knapp, J.

    1994-01-01

    Postflight orthostatic intolerance has been identified as a serious biomedical problem associated with long-duration exposure to microgravity in space. High priority has been given to the development of countermeasures for this disorder that are both effective and practical. A considerable body of clinical research has demonstrated that people can be taught to increase their own blood pressure voluntarily, and that this is an effective treatment for chronic orthostatic intolerance in paralyzed patients. The current pilot study was designed to examine the feasibility of adding training in control of blood pressure to an existing preflight training program designed to facilitate astronaut adaptation to microgravity. Using an operant conditioning procedure, autogenic-feedback training (AFT), three men and two women participated in four to nine training (15-30-minute) sessions. At the end of training, the average increase in systolic and diastolic pressure, as well as mean arterial pressures, that the subjects made ranged between 20 and 50 mm Hg under both supine and 45 deg head-up tilt conditions. These findings indicate that AFT may be a useful alternative treatment or supplement to existing approaches for preventing postflight orthostatic intolerance. Furthermore, the use of operant conditioning methods for training cardiovascular responses may contribute to the general understanding of the mechanisms of orthostatic intolerance.

  10. Autogenic Feedback Training Exercise and pilot performance: enhanced functioning under search-and-rescue flying conditions

    NASA Technical Reports Server (NTRS)

    Cowings, P. S.; Kellar, M. A.; Folen, R. A.; Toscano, W. B.; Burge, J. D.

    2001-01-01

    Studies have shown that autonomous mode behavior is one cause of aircraft fatalities due to pilot error. In such cases, the pilot is in a high state of psychological and physiological arousal and tends to focus on one problem, while ignoring more critical information. This study examined the effect of training in physiological self-recognition and regulation, as a means of improving crew cockpit performance. Seventeen pilots were assigned to the treatment and control groups matched for accumulated flight hours. The treatment group contained 4 pilots from HC-130 Hercules aircraft and 4 HH-65 Dolphin helicopter pilots; the control group contained 3 pilots of HC-130s and 6 helicopter pilots. During an initial flight, physiological data were recorded on each crewmember and an instructor pilot rated individual crew performance. Eight crewmembers were then taught to regulate their own physiological response levels using Autogenic-Feedback Training Exercise (AFTE). The remaining participants received no training. During a second flight, treatment participants showed significant improvement in performance (rated by the same instructor pilot as in pretests) while controls did not improve. The results indicate that AFTE management of high states of physiological arousal may improve pilot performance during emergency flying conditions.

  11. Response of spinal myoclonus to a combination therapy of autogenic training and biofeedback

    PubMed Central

    Sugimoto, Koreaki; Theoharides, Theoharis C; Kempuraj, Duraisamy; Conti, Pio

    2007-01-01

    Introduction Clinical evidence indicates that certain types of movement disorders are due to psychosomatic factors. Patients with myoclonic movements are usually treated by a variety of therapeutic agents. Autogenic training (AT), a recognized form of psychosomatic therapies, is suitable for certain types of neurological diseases. We describe a patient with myoclonus who failed to respond to conventional medical therapy. His symptoms were exaggerated by psychogenic factors, especially anger. Case presentation A 42-year-old man was admitted to our hospital, Preventive Welfare Clinic, for severe paroxysmal axial myoclonus of the left shoulder and abdominal muscles. The initial diagnosis was "combination of spinal segmental myoclonus and propriospinal myoclonus". The myoclonic movements did not occur during sleep but were aggravated by bathing, alcohol drinking, and anger. Psychological examination indicated hostile attribution. Although considered not to be a case of psychogenic myoclonus, a "psychogenic factor" was definitely involved in the induction of the organic myoclonus. The final diagnosis was "combination of spinal segmental myoclonus and propriospinal myoclonus accompanied by features of psychosomatic disorders". The patient underwent psychosomatic therapy including AT and surface electromyography (EMG)-biofeedback therapy and treatment with clonazepam and carbamazepine. Results AT and EMG-biofeedback resulted in shortening the duration and reducing the amplitude and frequency of the myoclonic discharges. Conclusion Psychosomatic therapy with AT and surface EMG-biofeedback produced excellent improvement of myoclonic movements and allowed the reduction of the dosage of conventional medications. PMID:17931427

  12. Autogenous regulation of RNA translation and packaging by Rous sarcoma virus Pr76gag.

    PubMed Central

    Sonstegard, T S; Hackett, P B

    1996-01-01

    Unspliced cytoplasmic retroviral RNA in chronically infected cells either is encapsidated by Gag proteins in the manufacture of virus or is used to direct synthesis of Gag proteins. Several models have been suggested to explain the sorting of viral RNA for these two purposes. Here we present evidence supporting a simple biochemical mechanism that accounts for the routing of retroviral RNA. Our results indicate that ribosomes compete with the Gag proteins to determine the fate of nascent retroviral RNA. Although the integrity of the entire Rous sarcoma virus leader sequence is important for retroviral packaging and translation, the RNA structure around the third small open reading frame, which neighbors the psi site required for packaging of the RNA, is particularly critical for maintenance of the balance between translation and packaging. These results support the hypothesis that Gag proteins autogenously regulate their synthesis and encapsidation of retroviral RNA and that an equilibrium exists between RNA destined for translation and packaging that is based on the intracellular levels of Gag proteins and ribosomes. To test the model, mRNAs with natural or mutated 5' leader sequences from Rous sarcoma virus were expressed in avian cells in the presence and absence of Pr76gag. We demonstrate that Pr76gag acts as a translational repressor of these mRNAs in a dose-dependent manner, supporting the hypothesis that Pr76gag can sort retroviral RNA for translation and encapsidation. PMID:8794299

  13. Centrifugation-assisted Assembly of Colloidal Silica into Crack-Free and Transferrable Films with Tunable Crystalline Structures

    PubMed Central

    Fan, Wen; Chen, Min; Yang, Shu; Wu, Limin

    2015-01-01

    Self-assembly of colloidal particles into colloidal films has many actual and potential applications. While various strategies have been developed to direct the assembly of colloidal particles, fabrication of crack-free and transferrable colloidal film with controllable crystal structures still remains a major challenge. Here we show a centrifugation-assisted assembly of colloidal silica spheres into free-standing colloidal film by using the liquid/liquid interfaces of three immiscible phases. Through independent control of centrifugal force and interparticle electrostatic repulsion, polycrystalline, single-crystalline and quasi-amorphous structures can be readily obtained. More importantly, by dehydration of silica particles during centrifugation, the spontaneous formation of capillary water bridges between particles enables the binding and pre-shrinkage of the assembled array at the fluid interface. Thus the assembled colloidal films are not only crack-free, but also robust and flexible enough to be easily transferred on various planar and curved substrates. PMID:26159121

  14. Centrifugation-assisted Assembly of Colloidal Silica into Crack-Free and Transferrable Films with Tunable Crystalline Structures.

    PubMed

    Fan, Wen; Chen, Min; Yang, Shu; Wu, Limin

    2015-07-10

    Self-assembly of colloidal particles into colloidal films has many actual and potential applications. While various strategies have been developed to direct the assembly of colloidal particles, fabrication of crack-free and transferrable colloidal film with controllable crystal structures still remains a major challenge. Here we show a centrifugation-assisted assembly of colloidal silica spheres into free-standing colloidal film by using the liquid/liquid interfaces of three immiscible phases. Through independent control of centrifugal force and interparticle electrostatic repulsion, polycrystalline, single-crystalline and quasi-amorphous structures can be readily obtained. More importantly, by dehydration of silica particles during centrifugation, the spontaneous formation of capillary water bridges between particles enables the binding and pre-shrinkage of the assembled array at the fluid interface. Thus the assembled colloidal films are not only crack-free, but also robust and flexible enough to be easily transferred on various planar and curved substrates.

  15. Crack problems in cylindrical and spherical shells

    NASA Technical Reports Server (NTRS)

    Erdogan, F.

    1976-01-01

    Standard plate or shell theories were used as a starting point to study the fracture problems in thin-walled cylindrical and spherical shells, assuming that the plane of the crack is perpendicular to the surface of the sheet. Since recent studies have shown that local shell curvatures may have a rather considerable effect on the stress intensity factor, the crack problem was considered in conjunction with a shell rather than a plate theory. The material was assumed to be isotropic and homogeneous, so that approximate solutions may be obtained by approximating the local shell crack geometry with an ideal shell which has a solution, namely a spherical shell with a meridional crack, a cylindrical shell with a circumferential crack, or a cylindrical shell with an axial crack. A method of solution for the specially orthotropic shells containing a crack was described; symmetric and skew-symmetric problems are considered in cylindrical shells with an axial crack.

  16. Crack Formation in Cement-Based Composites

    NASA Astrophysics Data System (ADS)

    Sprince, A.; Pakrastinsh, L.; Vatin, N.

    2016-04-01

    The cracking properties in cement-based composites widely influences mechanical behavior of construction structures. The challenge of present investigation is to evaluate the crack propagation near the crack tip. During experiments the tension strength and crack mouth opening displacement of several types of concrete compositions was determined. For each composition the Compact Tension (CT) specimens were prepared with dimensions 150×150×12 mm. Specimens were subjected to a tensile load. Deformations and crack mouth opening displacement were measured with extensometers. Cracks initiation and propagation were analyzed using a digital image analysis technique. The formation and propagation of the tensile cracks was traced on the surface of the specimens using a high resolution digital camera with 60 mm focal length. Images were captured during testing with a time interval of one second. The obtained experimental curve shows the stages of crack development.

  17. Interacting Cracks in an Environmentally Assisted Fracture

    NASA Astrophysics Data System (ADS)

    Levandovsky, Artem; Balazs, Anna

    2006-03-01

    We perform the study of environmentally assisted fracture within the framework of a lattice model. Formation of an ensemble of environmentally assisted microcracks, their coalescence and formation of crack ``avalanches'' lead to a very rich dynamical picture. Under specific condition crack healing can occur due to cohesive forces, which hold material together and tend to pull atoms together even if they are separated by a crack over several lattice units. We investigate the dynamical interplay between crack formation, arrest, healing and re-cracking. The goal here is to provide an understanding of the conditions leading to the phenomena of crack healing that happens along with the crack formation. We study the morphology of crack patterns with the intentions to establish a way to enhance the healing property of a material sample.

  18. Fracture mechanics parameters for small fatigue cracks

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.

    1992-01-01

    This paper presents a review of some common small-crack test specimens, the underlying causes of the small-crack effect, and the fracture-mechanics parameters that have been used to correlate or predict their growth behavior. This review concentrates on continuum mechanics concepts and on the nonlinear behavior of small cracks. The paper reviews some stress-intensity factor solutions for small-crack test specimens and develops some simple elastic-plastic J integral and cyclic J integral expressions that include the influence of crack-closure. These parameters were applied to small-crack growth data on two aluminum alloys, and a fatigue life prediction methodology is demonstrated. For these materials, the crack-closure transient from the plastic wake was found to be the major factor in causing the small-crack effect.

  19. TV fatigue crack monitoring system

    NASA Technical Reports Server (NTRS)

    Exton, R. J. (Inventor)

    1977-01-01

    An apparatus is disclosed for monitoring the development and growth of fatigue cracks in a test specimen subjected to a pulsating tensile load. A plurality of television cameras photograph a test specimen which is illuminated at the point of maximum tensile stress. The television cameras have a modified vidicon tube which has an increased persistence time thereby eliminating flicker in the displayed images.

  20. Methylecgonidine coats the crack particle.

    PubMed

    Wood, R W; Shojaie, J; Fang, C P; Graefe, J F

    1996-01-01

    Crack is a form of cocaine base self-administered by smoking. When heated, it volatilizes and may partially pyrolyze to methylecgonidine (MEG). Upon cooling, a condensation aerosol forms. Heating cocaine base in model crack pipes produced particles of about 1 micron in diameter, regardless of the amount heated; however, MEG concentration increased from < or = 2% at 10 mg per heating to as much as 5% at 30 mg per heating. Methylecgonidine was < or = 1% of the recovered material when cocaine was vaporized off a heated wire coil, but the particles were larger (2-5 microns), and the distribution disperse. The vapor pressure of MEG was higher [log P(mm Hg) = 9.994 - 3530/T] than cocaine base, consistent with MEG coating the droplet during condensation, and with evaporation during aging or dilution. Disappearance of MEG from a chamber filled with crack smoke was a two-component process, one proceeding at the rate of cocaine particle removal, and the other at the desorption rate from other surfaces. Particle diameter influences the deposition site in the respiratory tract; thus, the likely different patterns of deposition in the respiratory tract of humans and animals of crack aerosols produced by different techniques warrant consideration, as they may influence our understanding of immediate and delayed sequelae of the inhalation of cocaine and its pyrolysis product, MEG.

  1. Steam Hydrocarbon Cracking and Reforming

    ERIC Educational Resources Information Center

    Golombok, Michael

    2004-01-01

    The interactive methods of steam hydrocarbon reforming and cracking of the oil and chemical industries are scrutinized, with special focus on their resemblance and variations. The two methods are illustrations of equilibrium-controlled and kinetically-controlled processes, the analysis of which involves theories, which overlap and balance each…

  2. Confining crack propagation in defective graphene.

    PubMed

    López-Polín, Guillermo; Gómez-Herrero, Julio; Gómez-Navarro, Cristina

    2015-03-11

    Crack propagation in graphene is essential to understand mechanical failure in 2D materials. We report a systematic study of crack propagation in graphene as a function of defect content. Nanoindentations and subsequent images of graphene membranes with controlled induced defects show that while tears in pristine graphene span microns length, crack propagation is strongly reduced in the presence of defects. Accordingly, graphene oxide exhibits minor crack propagation. Our work suggests controlled defect creation as an approach to avoid catastrophic failure in graphene.

  3. Differential performance on the go/no-go task as a function of the autogenous-reactive taxonomy of obsessions: findings from a non-treatment seeking sample.

    PubMed

    Lee, Han-Joo; Yost, Brittanie P; Telch, Michael J

    2009-04-01

    It has been suggested that obsessive-compulsive disorder is characterized by impaired inhibitory control. Response inhibition is a cognitive process required for one to cancel or suppress dominant but inappropriate responses. The present study examined response inhibition among non-treatment seeking individuals diagnosed with OCD and individuals with low levels of OCD symptoms using a computerized visual go/no-go task. Specifically, we sought to examine a prediction from the autogenous-reactive subtype model of obsessions (Lee, H.-J., & Kwon, S.-M. (2003). Two different types of obsession: autogenous obsessions and reactive obsessions. Behaviour Research and Therapy, 41, 11-29; Lee, H.-J., & Telch, M. J. (2008). Autogenous obsessions and reactive obsessions. In J. Abramowitz, S. Taylor, & D. McKay (Eds.), Obsessive-compulsive disorder: subtypes and spectrum conditions. New York: Elsevier., asserting that OCD individuals presenting with the autogenous subtype of obsessions will display greater difficulty in inhibitory control relative to individuals presenting with obsessions of the reactive subtype. Results showed that individuals with OCD of the autogenous subtype displayed more deficient inhibitory control on the visual go/no-go task as indexed by a longer response delay between the original stimuli set and the reversed stimuli set compared to individuals with OCD of the reactive subtype or individuals with low levels of OCD symptoms.

  4. A study of crack closure in fatigue

    NASA Technical Reports Server (NTRS)

    Shih, T. T.; Wei, R. P.

    1973-01-01

    Crack closure phenomenon in fatigue was studied by using a Ti-6Al-4V titanium alloy. The occurrence of crack closure was directly measured by an electrical-potential method, and indirectly by load-strain measurement. The experimental results showed that the onset of crack closure depends on both the stress ratio, and the maximum stress intensity factor. No crack closure was observed for stress ratio, greater than 0.3 in this alloy. A two-dimensional elastic model was used to explain the behavior of the recorded load-strain curves. Closure force was estimated by using this model. Yield level stress was found near the crack tip. Based on this estimated closure force, the crack opening displacement was calculated. This result showed that onset of crack closure detected by electrical-potential measurement and crack-opening-displacement measurement is the same. The implications of crack closure on fatigue crack are considered. The experimental results show that crack closure cannot fully account for the effect of stress ratio, on crack growth, and that it cannot be regarded as the sole cause for delay.

  5. Cracked Teeth: A Review of the Literature

    PubMed Central

    Lubisich, Erinne B.; Hilton, Thomas J.; FERRACANE, JACK

    2013-01-01

    Although cracked teeth are a common problem for patients and dentists, there is a dearth of evidence-based guidelines on how to prevent, diagnose, and treat cracks in teeth. The purpose of this article is to review the literature to establish what evidence exists regarding the risk factors for cracked teeth and their prevention, diagnosis, and treatment. PMID:20590967

  6. Jumplike fatigue crack growth in compressor blades

    NASA Astrophysics Data System (ADS)

    Limar', L. V.; Demina, Yu. A.; Botvina, L. R.

    2014-04-01

    It is shown that power relations between the two main fractographic characteristics of fracture surfaces forming during jumplike fatigue crack growth, namely, the crack depth and the corresponding crack front length, can be used to estimate the fracture stress during vibration tests of the compressor blades of an aviation gas turbine engine, which are made of VT3-1 titanium alloy.

  7. Ultrastructural evaluation of shrinkage artefacts induced by fixatives and embedding resins on osteocyte processes and pericellular space dimensions.

    PubMed

    Shah, Furqan A; Johansson, Bengt R; Thomsen, Peter; Palmquist, Anders

    2015-04-01

    The integrity of the interface between the osteocyte (Ot) process and the canalicular wall was investigated in terms of change in the lateral dimensions of the Ot process in relation to the canalicular width, i.e., widening of the pericellular space. This has been interpreted as shrinkage of the Ot process relative to the canalicular wall during sample preparation stages of fixation, dehydration, and resin embedding. Sprague-Dawley rat tibial cross-sections were prepared for transmission electron microscopy (TEM). Four different fixative preparations: paraformaldehyde (PF), modified Karnovsky's (MK), glutaraldehyde (GRR) with ruthenium red (GRR), and zinc formalin (ZF); and two different embedding resins: LR Gold (LRG) and Epon812 (Epon) were evaluated. It was found that for LRG embedding, formalin-only fixatives (PF and ZF) induced lower shrinkage than GRR-containing fixatives (MK and GRR). In contrast, for Epon embedding, MK showed the highest shrinkage, while no differences were found between the remaining fixatives (PF, ZF, and GRR). All formalin-containing fixatives (MK, PF, and ZF) induced similar shrinkage in both embedding media. The most dramatic difference was for GRR fixation, which in combination with LRG embedding showed ∼ 62% more shrinkage than with Epon embedding, suggesting that the combination of GRR fixation and LRG embedding synergistically amplifies Ot shrinkage. These differences likely suggest a role of the resin in secondarily influencing the tissue structure following fixation. Further, the work confirms LRG as a poor embedding medium for bone specimens, as it causes large variations in shrinkage depending on fixation.

  8. Assessment of murine brain tissue shrinkage caused by different histological fixatives using magnetic resonance and computed tomography imaging.

    PubMed

    Wehrl, Hans F; Bezrukov, Ilja; Wiehr, Stefan; Lehnhoff, Mareike; Fuchs, Kerstin; Mannheim, Julia G; Quintanilla-Martinez, Leticia; Kohlhofer, Ursula; Kneilling, Manfred; Pichler, Bernd J; Sauter, Alexander W

    2015-05-01

    Especially for neuroscience and the development of new biomarkers, a direct correlation between in vivo imaging and histology is essential. However, this comparison is hampered by deformation and shrinkage of tissue samples caused by fixation, dehydration and paraffin embedding. We used magnetic resonance (MR) imaging and computed tomography (CT) imaging to analyze the degree of shrinkage on murine brains for various fixatives. After in vivo imaging using 7 T MRI, animals were sacrificed and the brains were dissected and immediately placed in different fixatives, respectively: zinc-based fixative, neutral buffered formalin (NBF), paraformaldehyde (PFA), Bouin-Holland fixative and paraformaldehyde-lysine-periodate (PLP). The degree of shrinkage based on mouse brain volumes, radiodensity in Hounsfield units (HU), as well as non-linear deformations were obtained. The highest degree of shrinkage was observed for PLP (68.1%, P < 0.001), followed by PFA (60.2%, P<0.001) and NBF (58.6%, P<0.001). The zinc-based fixative revealed a low shrinkage with only 33.5% (P<0.001). Compared to NBF, the zinc-based fixative shows a slightly higher degree of deformations, but is still more homogenous than PFA. Tissue shrinkage can be monitored non-invasively with CT and MR. Zinc-based fixative causes the smallest degree of brain shrinkage and only small deformations and is therefore recommended for in vivo ex vivo comparison studies.

  9. Subcritical crack propagation due to chemical rock weakening: macroscale chemo-plasticity and chemo-elasticity modeling

    NASA Astrophysics Data System (ADS)

    Hueckel, T.; Hu, M.

    2015-12-01

    Crack propagation in a subcritically stressed rock subject to chemically aggressive environment is analyzed and numerically simulated. Chemically induced weakening is often encountered in hydraulic fracturing of low-permeability oil/gas reservoirs and heat reservoirs, during storage of CO2 and nuclear waste corroding canisters, and other circumstances when rock matrix acidizing is involved. Upon acidizing, mineral mass dissolution is substantially enhanced weakening the rock and causing crack propagation and eventually permeability changes in the medium. The crack process zone is modeled mathematically via a chemo-plastic coupling and chemo-elastic coupling model. In plasticity a two-way coupling is postulated between mineral dissolution and a yield limit of rock matrix. The rate of dissolution is described by a rate law, but the mineral mass removal per unit volume is also a function of a variable internal specific surface area, which is in turn affected by the micro-cracking (treated as a plastic strain). The behavior of the rock matrix is modeled as rigid-plastic adding a chemical softening capacity to Cam-Clay model. Adopting the Extended Johnson's approximation of processes around the crack tip, the evolution of the stress field and deformation as a function of the chemically enhanced rock damage is modeled in a simplified way. In addition, chemical reactive transport is made dependent on plastic strain representing micro-cracking. Depending on mechanical and chemical boundary conditions, the area of enhanced chemical softening is near or somewhat away from the crack tip.In elasticity, chemo-mechanical effect is postulated via a chemical volumetric shrinkage strain proportional to mass removal variable, conceived analogously to thermal expansion. Two versions are considered: of constant coefficient of shrinkage and a variable one, coupled to deviatoric strain. Airy Potential approach used for linear elasticity is extended considering an extra term, which is

  10. Crack-opening displacements in center-crack, compact, and crack-line wedge-loaded specimens. [of flat plates

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.

    1976-01-01

    The theoretical crack-opening displacements for center-crack, compact, and crack-line wedge-loaded specimens (reported in the ASTM Proposed Recommended Practice for R-Curve Determination (1974)) disagree with experimental measurements in the literature. The disagreement is a result of using approximate specimen configurations and load representation to obtain the theoretical displacements. An improved method of boundary collocation is presented which was used to obtain the theoretical displacements in these three specimen types; the actual specimen configurations and more accurate load representation were used. In the analysis of crack-opening displacements in the compact and crack-line wedge-loaded specimens, the effects of the pin-loaded holes were also included. The theoretical calculations agree with the experimental measurements reported in the literature. Also examined are accurate polynomial expressions for crack-opening displacements in both compact and crack-line wedge-loaded specimens.

  11. Cracking behavior of structural slab bridge decks

    NASA Astrophysics Data System (ADS)

    Baah, Prince

    Bridge deck cracking is a common problem throughout the United States, and it affects the durability and service life of concrete bridges. Several departments of transportation (DOTs) in the United States prefer using continuous three-span solid structural slab bridges without stringers over typical four-lane highways. Recent inspections of such bridges in Ohio revealed cracks as wide as 0.125 in. These measured crack widths are more than ten times the maximum limit recommended in ACI 224R-01 for bridge decks exposed to de-icing salts. Measurements using digital image correlation revealed that the cracks widened under truck loading, and in some cases, the cracks did not fully close after unloading. This dissertation includes details of an experimental investigation of the cracking behavior of structural concrete. Prism tests revealed that the concrete with epoxy-coated bars (ECB) develops the first crack at smaller loads, and develops larger crack widths compared to the corresponding specimens with uncoated (black) bars. Slab tests revealed that the slabs with longitudinal ECB developed first crack at smaller loads, exhibited wider cracks and a larger number of cracks, and failed at smaller ultimate loads compared to the corresponding test slabs with black bars. To develop a preventive measure, slabs with basalt and polypropylene fiber reinforced concrete were also included in the test program. These test slabs exhibited higher cracking loads, smaller crack widths, and higher ultimate loads at failure compared to the corresponding slab specimens without fibers. Merely satisfying the reinforcement spacing requirements given in AASHTO or ACI 318-11 is not adequate to limit cracking below the ACI 224R-01 recommended maximum limit, even though all the relevant design requirements are otherwise met. Addition of fiber to concrete without changing any steel reinforcing details is expected to reduce the severity and extent of cracking in reinforced concrete bridge decks.

  12. Crack modeling of rotating blades with cracked hexahedral finite element method

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Jiang, Dongxiang

    2014-06-01

    Dynamic analysis is the basis in investigating vibration features of cracked blades, where the features can be applied to monitor health state of blades, detect cracks in an early stage and prevent failures. This work presents a cracked hexahedral finite element method for dynamic analysis of cracked blades, with the purpose of addressing the contradiction between accuracy and efficiency in crack modeling of blades in rotor system. The cracked hexahedral element is first derived with strain energy release rate method, where correction of stress intensity factors of crack front and formulation of load distribution of crack surface are carried out to improve the modeling accuracy. To consider nonlinear characteristics of time-varying opening and closure effects caused by alternating loads, breathing function is proposed for the cracked hexahedral element. Second, finite element method with contact element is analyzed and used for comparison. Finally, validation of the cracked hexahedral element is carried out in terms of breathing effects of cracked blades and natural frequency in different crack depths. Good consistency is acquired between the results with developed cracked hexahedral element and contact element, while the computation time is significantly reduced in the previous one. Therefore, the developed cracked hexahedral element achieves good accuracy and high efficiency in crack modeling of rotating blades.

  13. Crack branching in carbon steel. Fracture mechanisms

    NASA Astrophysics Data System (ADS)

    Syromyatnikova, A. S.; Alekseev, A. A.; Levin, A. I.; Lyglaev, A. V.

    2010-04-01

    The fracture surfaces of pressure vessels made of carbon steel that form during crack branching propagation are examined by fractography. Crack branching is found to occur at a crack velocity higher than a certain critical value V > V c . In this case, the material volume that is involved in fracture and depends on the elastoplastic properties of the material and the sample width has no time to dissipate the energy released upon crack motion via the damage mechanisms intrinsic in the material under given deformation conditions (in our case, via cracking according to intragranular cleavage).

  14. Crack use in São Paulo.

    PubMed

    Nappo, S A; Galduróz, J C; Noto, A R

    1996-04-01

    Documented crack use emerged in São Paulo, Brazil, from 1991 onward. Therefore, it is a recent behavior among drug users. The present work draws a profile of São Paulo crack users, employing an ethnographic approach. Twenty-five crack users were interviewed on selected social and demographic characteristics, on the drug itself and its consumption, and on the consequences of this use. Crack cocaine is harmful for the user, leading within a short period to a condition of dependence. The crack users reported ultimately lapsing into "marginality" due to social isolation, neglect of bodily needs, and breakdown of family ties and other relationships.

  15. A combined approach of enamel matrix derivative gel and autogenous bone grafts in treatment of intrabony periodontal defects. A case report.

    PubMed

    Leung, George; Jin, Lijian

    2003-04-01

    Enamel matrix derivative (EMD) has recently been introduced as a new modality in regenerative periodontal therapy. This case report demonstrates a combined approach in topical application of EMD gel (Emdogain) and autogenous bone grafts for treatment of intrabony defects and furcation involvement defects in a patient with chronic periodontitis. The seven-month post-surgery clinical and radiographic results were presented. The combined application of EMD gel with autogenous bone grafts in intrabony osseous defects resulted in clinically significant gain of attachment on diseased root surfaces and bone fill on radiographs. Further controlled clinical studies are required to confirm the long-term effectiveness of the combination of EMD gel and autogenous bone grafts in treatment of various osseous defects in subjects with chronic periodontitis.

  16. Modified Weaver-Dunn Procedure Versus The Use of Semitendinosus Autogenous Tendon Graft for Acromioclavicular Joint Reconstruction

    PubMed Central

    Hegazy, Galal; Safwat, Hesham; Seddik, Mahmoud; Al-shal, Ehab A.; Al-Sebai, Ibrahim; Negm, Mohame

    2016-01-01

    Background: The optimal operative method for acromioclavicular joint reconstruction remains controversial. The modified Weaver-Dunn method is one of the most popular methods. Anatomic reconstruction of coracoclavicular ligaments with autogenous tendon grafts, widely used in treating chronic acromioclavicular joint instability, reportedly diminishes pain, eliminates sequelae, and improves function as well as strength. Objective: To compare clinical and radiologic outcomes between a modified Weaver-Dunn procedure and an anatomic coracoclavicular ligaments reconstruction technique using autogenous semitendinosus tendon graft. Methods: Twenty patients (mean age, 39 years) with painful, chronic Rockwood type III acromioclavicular joint dislocations were subjected to surgical reconstruction. In ten patients, a modified Weaver-Dunn procedure was performed, in the other ten patients; autogenous semitendinosus tendon graft was used. The mean time between injury and the index procedure was 18 month (range from 9 – 28). Clinical evaluation was performed using the Oxford Shoulder Score and Nottingham Clavicle Score after a mean follow-up time of 27.8 months. Preoperative and postoperative radiographs were compared. Results: In the Weaver-Dunn group the Oxford Shoulder Score improved from 25±4 to 40±2 points. While the Nottingham Clavicle Score increased from 48±7 to 84±11. In semitendinosus tendon graft group, the Oxford Shoulder Score improved from 25±3 points to 50±2 points and the Nottingham Clavicle Score from 48±8 points to 95±8, respectively. Conclusion: Acromioclavicular joint reconstruction using the semitendinosus tendon graft achieved better Oxford Shoulder Score and Nottingham Clavicle Score compared to the modified Weaver-Dunn procedure. PMID:27347245

  17. Self-organization in irregular landscapes: Detecting autogenic interactions from field data using descriptive statistics and dynamical systems theory

    NASA Astrophysics Data System (ADS)

    Larsen, L.; Watts, D.; Khurana, A.; Anderson, J. L.; Xu, C.; Merritts, D. J.

    2015-12-01

    The classic signal of self-organization in nature is pattern formation. However, the interactions and feedbacks that organize depositional landscapes do not always result in regular or fractal patterns. How might we detect their existence and effects in these "irregular" landscapes? Emergent landscapes such as newly forming deltaic marshes or some restoration sites provide opportunities to study the autogenic processes that organize landscapes and their physical signatures. Here we describe a quest to understand autogenic vs. allogenic controls on landscape evolution in Big Spring Run, PA, a landscape undergoing restoration from bare-soil conditions to a target wet meadow landscape. The contemporary motivation for asking questions about autogenic vs. allogenic controls is to evaluate how important initial conditions or environmental controls may be for the attainment of management objectives. However, these questions can also inform interpretation of the sedimentary record by enabling researchers to separate signals that may have arisen through self-organization processes from those resulting from environmental perturbations. Over three years at Big Spring Run, we mapped the dynamic evolution of floodplain vegetation communities and distributions of abiotic variables and topography. We used principal component analysis and transition probability analysis to detect associative interactions between vegetation and geomorphic variables and convergent cross-mapping on lidar data to detect causal interactions between biomass and topography. Exploratory statistics revealed that plant communities with distinct morphologies exerted control on landscape evolution through stress divergence (i.e., channel initiation) and promoting the accumulation of fine sediment in channels. Together, these communities participated in a negative feedback that maintains low energy and multiple channels. Because of the spatially explicit nature of this feedback, causal interactions could not

  18. The incorporation of allogeneic and autogenous bone graft in healing of lateral column lengthening of the calcaneus.

    PubMed

    Templin, David; Jones, Kerwyn; Weiner, Dennis S

    2008-01-01

    Lateral column calcaneal lengthening as described by Mosca is a widely accepted technique for the correction of hindfoot valgus and pes planus. It is performed with both allogeneic and autogenous bone graft. The purpose of this study was to evaluate the incorporation of these 2 types of bone graft in this procedure. A retrospective review of all lateral calcaneal lengthenings performed by 4 pediatric orthopaedic surgeons over a 10-year period was conducted. Radiographs at the last follow-up visit were independently examined by 3 reviewers. Incorporation of the bone graft was determined by 2 criteria: (1) presence of continuity of trabecular lines between graft and native bone, and (2) inability to distinguish the boundary between bone graft and native bone. A consensus or majority opinion (2 out of 3 reviewers) was considered positive for graft incorporation. Thirty-five lateral column lengthenings in 26 patients were reviewed, 30 of which used allograft bone and 5 autograft. Ninety-seven percent of the allograft cases and 80% of the autograft cases were incorporated at final follow-up. There was 1 case of graft failure in each of the 2 groups. Follow-up in the allograft failure was 6 weeks; the autogenous failure 7.2 years. Interrater reliability was good (kappa=0.61, P < .0001). No adverse events or complications were noted with the use of allograft bone in this series. Allogeneic bone graft is rapidly integrated into native bone and is a desirable substitute to autogenous bone for use in lateral column lengthenings, avoiding any patient morbidity from graft harvesting.

  19. Microcirculatory Response In Vivo on Local Intraarterial Infusion of Autogenic Adipose-derived Stem Cells or Stromal Vascular Fraction

    PubMed Central

    2016-01-01

    Background: Both adipose-derived stem cells (ASCs) and stromal vascular fraction (SVF) have been demonstrated to have regenerative properties with therapeutic potential for numerous diseases through local or topical applications. However, it is unclear whether ASC or SVF can be delivered systemically through an intra-arterial infusion. The purpose of this study was to examine the microcirculatory response in vivo on local intraarterial infusion of autogenic ASCs or SVF in a vascular pedicle isolated rat cremaster microcirculation model. Materials and Methods: Fat tissue was surgically harvested from the flanks of male Sprague–Dawley rats (n = 12) and processed for SVF isolation. Some SVF samples were cultured for 24 hours for ASC purification. The autogenic SVF (1 × 105) cells (n = 6) or purified ASC (1 × 105) cells (n = 6) cells were infused into the microcirculation of cremaster muscle at a speed of 0.05 mL/min through the cannulation of femoral artery. As this is a vascular pedicle isolated preparation, the infused SVF or ASC cells went nowhere but the cremaster muscle. The video image of the microcirculation was monitored in real time during infusion. Results: Arteriole diameter was measured as A1 (100–160 µm), A2 (40–80 µm), and A3/A4 (10–30 µm). Capillary perfusion was quantified in 18 capillary fields of each muscle. There was a significant increase in the diameter of terminal arterioles (P = 0.049) and the capillary density (P = 0.02) after ASC intraarterial infusion. However, a significant cell aggregation, embolisms, and arterial obstruction were observed in the microcirculation in every case during SVF infusion. Conclusions: Intraarterial infusion is an appropriate route for the delivery of autogenic ASCs, but not of SVF. SVF-induced microembolisms were the reason for narrowing or blocking the lumen of terminal arterioles, resulting in no flow in the corresponding capillaries. PMID:27757364

  20. Effect of selected physical properties of waxes on investments and casting shrinkage.

    PubMed

    Ito, M; Yamagishi, T; Oshida, Y; Munoz, C A

    1996-02-01

    This study evaluated the relationship between flow characteristics, bending strength, and softening temperature of paraffin and dental inlay waxes to casting shrinkage when patterns were invested with a phosphate-bonded investment. This study found that the casting shrinkage decreased as the flow of the wax pattern increased. If a low flow wax is used or if there is a need for a thick pattern, the size of the casting ring should be increased. When wax patterns are formed for cast restorations, it is important to select the type of wax with the most desirable properties for the margin and the occlusal portions. Moreover, to accurately fabricate castings, it is necessary to understand the physical properties of the chosen waxes.

  1. Non-linear shrinkage estimation of large-scale structure covariance

    NASA Astrophysics Data System (ADS)

    Joachimi, Benjamin

    2017-03-01

    In many astrophysical settings, covariance matrices of large data sets have to be determined empirically from a finite number of mock realizations. The resulting noise degrades inference and precludes it completely if there are fewer realizations than data points. This work applies a recently proposed non-linear shrinkage estimator of covariance to a realistic example from large-scale structure cosmology. After optimizing its performance for the usage in likelihood expressions, the shrinkage estimator yields subdominant bias and variance comparable to that of the standard estimator with a factor of ∼50 less realizations. This is achieved without any prior information on the properties of the data or the structure of the covariance matrix, at a negligible computational cost.

  2. Quantitative investigation of chemical shrinkage stress in flip chip using a 3D moire interferometry system

    NASA Astrophysics Data System (ADS)

    Su, Fei; Liu, Lie; Yi, Sung; Chian, Kerm S.

    2002-06-01

    Thermo-mechanical reliability is a key issue of IC packaging. In this paper, the chemical shrinkage stress caused by the underfill curing is quantitatively investigated: DSC test result provides the basis for the determination of temperature profile for the curing of underfill. The 3D deformation of the flip chip during the underfill curing process is measured with 3D Moire interferometry system. Also a simple theoretical model is set up for this problem, DMA test provide the necessary parameters for this model. The experimental and theoretical results agree well with each other, both results show that the chemical shrinkage stress is fairly small when compared with the thermal residual stress, so this part of residual stress can be neglected in the commonly used finite element analysis (FEA) model.

  3. Seislet-based morphological component analysis using scale-dependent exponential shrinkage

    NASA Astrophysics Data System (ADS)

    Yang, Pengliang; Fomel, Sergey

    2015-07-01

    Morphological component analysis (MCA) is a powerful tool used in image processing to separate different geometrical components (cartoons and textures, curves and points etc.). MCA is based on the observation that many complex signals may not be sparsely represented using only one dictionary/transform, however can have sparse representation by combining several over-complete dictionaries/transforms. In this paper we propose seislet-based MCA for seismic data processing. MCA algorithm is reformulated in the shaping-regularization framework. Successful seislet-based MCA depends on reliable slope estimation of seismic events, which is done by plane-wave destruction (PWD) filters. An exponential shrinkage operator unifies many existing thresholding operators and is adopted in scale-dependent shaping regularization to promote sparsity. Numerical examples demonstrate a superior performance of the proposed exponential shrinkage operator and the potential of seislet-based MCA in application to trace interpolation and multiple removal.

  4. Accelerated Path-following Iterative Shrinkage Thresholding Algorithm with Application to Semiparametric Graph Estimation

    PubMed Central

    Zhao, Tuo; Liu, Han

    2016-01-01

    We propose an accelerated path-following iterative shrinkage thresholding algorithm (APISTA) for solving high dimensional sparse nonconvex learning problems. The main difference between APISTA and the path-following iterative shrinkage thresholding algorithm (PISTA) is that APISTA exploits an additional coordinate descent subroutine to boost the computational performance. Such a modification, though simple, has profound impact: APISTA not only enjoys the same theoretical guarantee as that of PISTA, i.e., APISTA attains a linear rate of convergence to a unique sparse local optimum with good statistical properties, but also significantly outperforms PISTA in empirical benchmarks. As an application, we apply APISTA to solve a family of nonconvex optimization problems motivated by estimating sparse semiparametric graphical models. APISTA allows us to obtain new statistical recovery results which do not exist in the existing literature. Thorough numerical results are provided to back up our theory. PMID:28133430

  5. Light-Curing Volumetric Shrinkage in Dimethacrylate-Based Dental Composites by Nanoindentation and PAL Study

    NASA Astrophysics Data System (ADS)

    Shpotyuk, Olha; Adamiak, Stanislaw; Bezvushko, Elvira; Cebulski, Jozef; Iskiv, Maryana; Shpotyuk, Oleh; Balitska, Valentina

    2017-01-01

    Light-curing volumetric shrinkage in dimethacrylate-based dental resin composites Dipol® is examined through comprehensive kinetics research employing nanoindentation measurements and nanoscale atomic-deficient study with lifetime spectroscopy of annihilating positrons. Photopolymerization kinetics determined through nanoindentation testing is shown to be described via single-exponential relaxation function with character time constants reaching respectively 15.0 and 18.7 s for nanohardness and elastic modulus. Atomic-deficient characteristics of composites are extracted from positron lifetime spectra parameterized employing unconstrained x3-term fitting. The tested photopolymerization kinetics can be adequately reflected in time-dependent changes observed in average positron lifetime (with 17.9 s time constant) and fractional free volume of positronium traps (with 18.6 s time constant). This correlation proves that fragmentation of free-volume positronium-trapping sites accompanied by partial positronium-to-positron traps conversion determines the light-curing volumetric shrinkage in the studied composites.

  6. A moment projection method for population balance dynamics with a shrinkage term

    NASA Astrophysics Data System (ADS)

    Wu, Shaohua; Yapp, Edward K. Y.; Akroyd, Jethro; Mosbach, Sebastian; Xu, Rong; Yang, Wenming; Kraft, Markus

    2017-02-01

    A new method of moments for solving the population balance equation is developed and presented. The moment projection method (MPM) is numerically simple and easy to implement and attempts to address the challenge of particle shrinkage due to processes such as oxidation, evaporation or dissolution. It directly solves the moment transport equation for the moments and tracks the number of the smallest particles using the algorithm by Blumstein and Wheeler (1973) [41]. The performance of the new method is measured against the method of moments (MOM) and the hybrid method of moments (HMOM). The results suggest that MPM performs much better than MOM and HMOM where shrinkage is dominant. The new method predicts mean quantities which are almost as accurate as a high-precision stochastic method calculated using the established direct simulation algorithm (DSA).

  7. Improved imaging algorithm for bridge crack detection

    NASA Astrophysics Data System (ADS)

    Lu, Jingxiao; Song, Pingli; Han, Kaihong

    2012-04-01

    This paper present an improved imaging algorithm for bridge crack detection, through optimizing the eight-direction Sobel edge detection operator, making the positioning of edge points more accurate than without the optimization, and effectively reducing the false edges information, so as to facilitate follow-up treatment. In calculating the crack geometry characteristics, we use the method of extracting skeleton on single crack length. In order to calculate crack area, we construct the template of area by making logical bitwise AND operation of the crack image. After experiment, the results show errors of the crack detection method and actual manual measurement are within an acceptable range, meet the needs of engineering applications. This algorithm is high-speed and effective for automated crack measurement, it can provide more valid data for proper planning and appropriate performance of the maintenance and rehabilitation processes of bridge.

  8. Current concepts and future approaches to the development of autologous/autogenous vaccines for veterinary use.

    PubMed

    Tollis, M

    2004-01-01

    Current classification of autologous/autogenous (A/A) vaccines is commonly based on the concept of strain/antigen specificity associated with targeted treatment of a restricted number of animals. However, fulfilling these two conditions is not sufficient for immune-veterinary immunebiologicals to be excluded from the provisions of Directive 2001/82/EC. Indeed, non-inactivated A/A vaccines are not automatically considered out of the scope of the community code relating to veterinary medicinal products, in particular to immune-biologicals. As a major consequence of the "regulatory" exclusion from the requirements of EU rules, A/A vaccines can be usually manufactured and distributed without having obtained a marketing authorization by the competent authority of a Member State. Furthermore, strain specificity enables veterinarians to consider the use of these vaccines in quite a large variety of epidemiological circumstances where no "conventional" vaccines are yet available or are considered efficacious. In addition, in contrast to "conventional" vaccines, which are considered exclusively as a preventive tool against infectious diseases, A/A vaccines can also be used to treat "continuing" infections. Although the limited scientific value of these products and the poor investigations of the effector mechanisms involved are widely recognized, their use is still claimed in conditions where disorders in the immune system are suspected. Today, a more appropriate definition of A/A vaccines is one that takes into account their historical tradition and practical use, such as stable- or herd-specific vaccines, custom ("..ized") vaccines, therapeutic vaccines, pharmavaccines, vaccines used for biological therapy, etc. Although acknowledging the "regulatory autonomy" of A/A vaccines versus "conventional" vaccines, here it will be presented as an overview of the necessary points to consider, to guarantee an acceptable standard in the development and control of this particular

  9. Antibody response of autogenous splenic tissue implanted in the abdominal cavity of mice.

    PubMed

    Nunes, Sérgio I; Rezende, Alice B; Teixeira, Francisco M; Ferreira, Ana Paula; Alves, Márcio M J; Jamel, Nelson; Assis, Raimunda V C; Teixeira, Henrique C

    2005-12-01

    There is still controversy about the immunologic function of autotransplanted splenic tissue. In this study, splenic autotransplantation was performed in the abdominal cavity of mice, and the plaque-forming cell (PFC) assay was used to investigate the frequency of antibody-forming cells in response to sheep red blood cell (SRBC) immunization. BALB/c mice were divided into four groups according to the location of the autogenous graft: intraomental (IO), free peritoneal splenosis (FPS), retroperitoneal (RP), and nongrafted control (CT). Thirty days after surgery the mice were immunized intraperitoneally with SRBCs, and 4 days later splenic immunoglobulin M anti-SRBC-secreting cells were determined by counting the number of PFCs. All the immunized mice showed increased numbers of PFCs that were about 2 logs higher than those in the the nonimmunized controls (P < 0.005). The frequencies of anti-SRBC-producing cells in the tissues grafted in various sites of the abdominal cavity (IO, FPS, RP), in the normal spleen from nonoperated controls (CT), or in the sham-operated control group (SCT) were not notably different (5582 +/- 2475 PFC/10(7) cells for IO; 4849 +/- 1856 for FPS; 6604 +/- 2903 for RP; 5940 +/- 5029 for CT; and 6172 +/- 2203 for SCT). Similar histology with small architectural variations was observed in all implants; less white pulp was involved, and there was more congestion in the red pulp, with extensive sinusoids and reticular fiber proliferation. This study shows that the T cell-dependent antibody response in implanted splenic tissues is as efficient as in the intact spleen, with no difference between the graft sites studied. This immune response does not depend on the slight architectural variations observed in the splenic implants.

  10. NASA-Navy Telemedicine: Autogenic Feedback Training Exercises for Motion Sickness

    NASA Technical Reports Server (NTRS)

    Acromite, Michael T.; Cowings, Patricia; Toscano, William; Davis, Carl; Porter, Henry O.

    2010-01-01

    Airsickness is the most significant medical condition affecting naval aviation training. A 2001 study showed that airsickness was reported in 81% of naval aviation students and was associated with 82% of below average flight scores. The cost to a single training air-wing was over $150,000 annually for fuel and maintenance costs alone. Resistent cases are sent to the Naval Aerospace Medical Institute (NAMI) for evaluation and desensitization in the self-paced airsickness desensitization (SPAD) program. This approach is 75% successful, but can take up to 8 weeks at a significant travel cost. NASA Ames Research Center's Autogenic Feedback Training Exercises (AFTE) uses physiological and biofeedback training for motion sickness prevention. It has a remote capability that has been used from Moffett Field, CA to Atlanta, GA . AFTE is administered in twelve (30-minute) training sessions. The success rate for the NASA AFTE program has been over 85%. Methods: Implementation Phases: Phase I: Transfer NASA AFTE to NAMI; NASA will remotely train aviation students at NAMI. Phase II: NAMI-centered AFTE application with NASA oversight. Phase III: NAMI-centered AFTE to remotely train at various Navy sites. Phase IV: NAMI to offer Tri-service application and examine research opportunities. Results: 1. Use available telemedicine connectivity between NAMI and NASA. 2. Save over $2,000 per student trained. 3. Reduce aviation training attrition. 4. Provide standardization of multi-location motion sickness training. 5. Future tri-service initiatives. 6. Data to NASA and Navy for QA and research opportunities.

  11. Autogenic Scour and Channel Widening in Sharp Bends of the River Mahakam

    NASA Astrophysics Data System (ADS)

    Hoitink, T.; Vermeulen, B.; van Berkum, S.; Hidayat, H.; Labeur, R. J.

    2014-12-01

    Field evidence of the River Mahakam reveals autogenic scour and channel widening in a series of sharp bends. An integral analysis of a 300 km reach of the river is presented, including a comprehensive survey of the river banks, delineation of the river corridor from radar observations, Large Eddy Simulations of observed flow patterns, and a geometric analysis of planform and depth information. Scour depths strongly exceed what can be expected based on existing understanding of sharp bends, and are highly correlated with curvature. Histograms of the occurrence of erosive, stable, advancing, and bar-type banks as a function of curvature quantify the switch from a mildly curved bend regime to a sharp bend regime. In mild bends, outer banks erode and inner banks advance. In sharp bends the erosion pattern inverts. Outer banks stabilize or advance, while inner banks erode. In sharply curved river bends, bars occur near the outer banks that become less erosive for higher curvatures. Inner banks become more erosive for higher curvatures, but nevertheless accommodate the larger portion of exposed bars. Soil processes may play a crucial role in the formation of sharp bends, which is inferred from iron and manganese concretions observed in the riverbanks, indicating ferric horizons and early stages of the formation of plinthic horizons. Historical topographic maps show the planform activity of the river is low, which may relate to the scours slowing down planimetric development. The occurrence of exceptionally deep scours is attributed to downflow near the scour exceeding 12 cm/s, increasing the bed shear stress. The downflow, in turn, is explained from the cross-sectional area increase, which is shown to be important in generating adverse surface gradients driving flow recirculation in the Large Eddy Simulations. Strong secondary flow distorts the vertical pressure distribution that is no longer hydrostatic. The downflow advects longitudinal momentum, moving the core of the

  12. Afferents contributing to autogenic inhibition of gastrocnemius following electrical stimulation of its tendon.

    PubMed

    Khan, Serajul I; Burne, John A

    2009-07-28

    Electrical stimulation of the Achilles tendon produced strong reflex inhibition of the ongoing voluntary EMG activity in the two heads of the gastrocnemius (GA) muscle in all tested subjects. The inhibition was seen clearly in both averaged and single sweep surface EMG records. The inhibitory response was produced without electrical (M wave) or mechanical, (muscle twitch) signs of direct muscle stimulation. The onset latency and duration for the first period of inhibition (I(1)) were 47-49 ms and 67 ms, respectively. A second inhibition (I(2)) had an onset latency of 187-193 ms and duration under 40 ms. Non-noxious stimuli in the range of 2.6-7.6 x mean perceptual threshold, when delivered to four locations over the GA tendon, all produced clear inhibition of the voluntary muscle activity. The inhibition was maximal when the cathode was a large metal plate located near the musculotendinous junction and decreased approximately linearly with distances more distal to that site. The effect of passive muscle stretch on the electrically induced tendon reflex inhibition (TRE) was tested at ankle joint angles incremented in steps of 20 degrees. It was found that TRE is strongly dependent on joint angle, being maximal in the fully stretched muscle. TRE was lost completely after partial tibial nerve block. In comparison, GA inhibition produced by cutaneous (sural) nerve stimulation was of a higher threshold, longer latency and persisted after partial tibial nerve block. We thus demonstrated a powerful autogenic inhibition in the lower limb arising from tendon afferents in conscious subjects that is increased by passive muscle stretch and likely to originate from group I tendon afferents.

  13. Hydraulic and sediment transport properties of autogenic avulsion cycles on submarine fans with supercritical distributaries

    NASA Astrophysics Data System (ADS)

    Hamilton, Paul B.; Strom, Kyle B.; Hoyal, David C. J. D.

    2015-07-01

    Submarine fans, like other distributive systems, are built by repeated avulsion cycles. However, relative to deltas and alluvial fans, much less is known about avulsions in subaqueous settings. In this study, we ran a set of subaqueous fan experiments to investigate the mechanics associated with autogenic avulsion cycles of self-formed channels and lobe deposits on steep slopes. The experiments used saline density currents with crushed plastic to emulate sustained turbidity currents and bed load transport. We collected detailed hydraulic and bathymetric measurements and made use of a 1-D laterally expanding density current model to better understand different aspects of the avulsion cycle. Our results reveal three major components of the avulsion cycles: (1) distributary channel incision, extension, and stagnation; (2) mouth bar aggradation and hydraulic jump initiation; and (3) hydraulic jump sedimentation and upstream retreat. Interestingly, in all but one experiment, the avulsion cycles led to fans that remained perched above the basin slope break. Experimental data and hydraulic theory were used to unravel actual mechanics associated with cycles. We found that channels stopped extending into the basin due to a decay in sediment transport capacity relative to sediment supply and that the reduction in capacity was primarily an outcome of expansion-driven velocity reduction; dilution played a secondary role. Once channel extension ceased, mouth bar deposits aggraded to a thickness approximately equal to the critical step height needed to create a choked flow condition. The choke then initiated a hydraulic jump on the upstream side of the bar. Once formed, the jump detained a majority of the incoming sediment and forced the channel-to-lobe transition upstream, filling the channel with steep backset bedding and capping the entire channel with a mounded lobate deposit. These intrinsic processes repeated through multiple avulsion cycles to build the fan.

  14. Autogenic-feedback training exercise is superior to promethazine for control of motion sickness symptoms.

    PubMed

    Cowings, P S; Toscano, W B

    2000-10-01

    Motion sickness symptoms affect approximately 50% of the crew during space travel and are commonly treated with intramuscular injections of promethazine. The purpose of this paper is to compare the effectiveness of three treatments for motion sickness: intramuscular injections (i.m.) of promethazine, a physiological training method (autogenic-feedback training exercise [AFTE]), and a no-treatment control. An earlier study tested the effects of promethazine on cognitive and psychomotor performance and motion sickness tolerance in a rotating chair. For the present paper, motion sickness tolerance, symptom reports, and physiological responses of these subjects were compared to matched subjects selected from an existing database who received either AFTE or no treatment. Three groups of 11 men, between the ages of 33 and 40 years, were matched on the number of rotations tolerated during their initial rotating-chair motion sickness test. The motion sickness test procedures and the 7-day interval between tests were the same for all subjects. The drug group was tested under four treatment conditions: baseline (no injections), a 25 mg dose of promethazine, a 50 mg dose of promethazine, and a placebo of sterile saline. AFTE subjects were given four 30-minute AFTE sessions before their second, third, and fourth motion sickness tests (6 hours total). The no-treatment control subjects were only given the four rotating-chair tests. Motion sickness tolerance was significantly increased after 4 hours of AFTE when compared to either 25 mg (p < 0.00003) or 50 mg (p < 0.00001) of promethazine. The control and promethazine groups did not differ. AFTE subjects reported fewer or no symptoms at higher rotational velocities than subjects in the control or promethazine groups. The primary physiological effect of promethazine was an inhibition of skin conductance level. The AFTE group showed significantly less heart rate and skin conductance variability during motion sickness tests

  15. [Autogenic training in children and adolescents with type 1 diabetes mellitus].

    PubMed

    Göhr, M; Röpcke, B; Pistor, K; Eggers, C

    1997-04-01

    This paper discusses psychosocial influences of diabetes mellitus type 1 on children and young patients. A group of 21 patients, age 9 to 14 years with Diabetes mellitus type 1 attended a course in "Autogenic Training" for a period of 11 weeks. From the multidimensional questionnaire for children (PFK 9-14, SETZ U. RAUSCHE 1976) 15 dimensions of personality and 5 second rank factors were extracted at the beginning and at the end of training and 5 months later. Additionally HbA1-scores were assessed at the beginning and at the end at a 2 month and a 5 month-follow-up. At the beginning of the course only on one of the 15 scales a significant difference could be observed between experimental group and age related normal population. After training 5 scales and one second rank factor showed significant changes. Significant reduction was observed in: "need for aggressive forms of dominance behaviour" "feeling of submission with respects to other:", "emotional lability" and "tendency for dependence on adults". A significantly increased score was observed in the scale measuring "self confidence regarding one's own meaning, decisions and planning ability". The second rank faktor "neuroticism" was significantly reduced. Against expectations there was no reduction in HbA1 scores. At the end of training HbA1 scores even had increased significantly. But this might have been related to the high frequency of infections during this course. In subjective ratings of training evaluation most of the course members and their parents described fewer problems with attention, less test-anxiety and less aggression and nervousness. The results of this prospective pilot-study are discussed in terms of the psychodynamic influence on diabetes.

  16. Autogenic-feedback training exercise is superior to promethazine for control of motion sickness symptoms

    NASA Technical Reports Server (NTRS)

    Cowings, P. S.; Toscano, W. B.

    2000-01-01

    Motion sickness symptoms affect approximately 50% of the crew during space travel and are commonly treated with intramuscular injections of promethazine. The purpose of this paper is to compare the effectiveness of three treatments for motion sickness: intramuscular injections (i.m.) of promethazine, a physiological training method (autogenic-feedback training exercise [AFTE]), and a no-treatment control. An earlier study tested the effects of promethazine on cognitive and psychomotor performance and motion sickness tolerance in a rotating chair. For the present paper, motion sickness tolerance, symptom reports, and physiological responses of these subjects were compared to matched subjects selected from an existing database who received either AFTE or no treatment. Three groups of 11 men, between the ages of 33 and 40 years, were matched on the number of rotations tolerated during their initial rotating-chair motion sickness test. The motion sickness test procedures and the 7-day interval between tests were the same for all subjects. The drug group was tested under four treatment conditions: baseline (no injections), a 25 mg dose of promethazine, a 50 mg dose of promethazine, and a placebo of sterile saline. AFTE subjects were given four 30-minute AFTE sessions before their second, third, and fourth motion sickness tests (6 hours total). The no-treatment control subjects were only given the four rotating-chair tests. Motion sickness tolerance was significantly increased after 4 hours of AFTE when compared to either 25 mg (p < 0.00003) or 50 mg (p < 0.00001) of promethazine. The control and promethazine groups did not differ. AFTE subjects reported fewer or no symptoms at higher rotational velocities than subjects in the control or promethazine groups. The primary physiological effect of promethazine was an inhibition of skin conductance level. The AFTE group showed significantly less heart rate and skin conductance variability during motion sickness tests

  17. In vitro expression of Escherichia coli ribosomal protein genes: autogenous inhibition of translation.

    PubMed Central

    Yates, J L; Arfsten, A E; Nomura, M

    1980-01-01

    Escherichia coli ribosomal protein L1 (0.5 micro M) was found to inhibit the synthesis of both proteins of the L11 operon, L11 and L1, but not the synthesis of other proteins directed by lambda rifd 18 DNA. Similarly, S4 (1 micro M) selectively inhibited the synthesis of three proteins of the alpha operon, S13, S11, and S4, directed by lambda spcI DNA or a restriction enzyme fragment obtained from this DNA. S8 (3.6 micro M) also showed preferential inhibitory effects on the synthesis of some proteins encoded in the spc operon, L24 and L5 (and probably S14 and S8), directed by lambda spcl DNA or a restriction enzyme fragment carrying the genes for these proteins. The inhibitory effect of L1 was observed only with L1 and not with other proteins examined, including S4 and S8. Similarly, the effect of S4 was not observed with L1 or S8, and that of S8 was not seen with L1 or S4. Inhibition was shown to take place at the level of translation rather than transcription. Thus, at least some ribosomal proteins (L1 S4, and S8) have the ability to cause selective translational inhibition of the synthesis of certain ribosomal proteins whose genes are in the same operon as their own. These results support the hypothesis that certain free ribosomal proteins not assembled into ribosomes act as "autogenous" feedback inhibitors to regulate the synthesis of ribosomal proteins. Images PMID:6445562

  18. Co-Graft of Acellular Dermal Matrix and Autogenous Microskin in a Child with Extensive Burns

    PubMed Central

    Chen, X.L.; Xia, Z.F.; Fang, L.S.; Wang, Y.J.; Wang, C.H.

    2008-01-01

    Summary A 6-yr-old boy was the victim of a burns accident in a public bathhouse. The burns involved the face, neck, upper and lower extremities, anterior and posterior trunk, and both buttocks, covering 72% of the total body surface area (TBSA). The lesions in the lower extremities and parts of the right upper extremity were deep partial-thickness, comprising 40% TBSA. On day 5 post-burn, the lesions in both lower extremities were excised to the extent of the fascia under general anaesthesia. Meshed J1 Jayya Acellular Dermis®, a kind of acellular allodermal (ADM) matrix, was then placed on the left knee joint. The right knee joint served as control. The wounds in both lower extremities were then overlaid with microskin autografting. At 19 days post-application, the lesions in both lower extremities had almost completely resurfaced. Follow-up at six months revealed well-healed and stable skin of acellular ADM and microskin autografts on the left knee. However, the skin of the right knee was unstable and there was a chronic residual ulcer. Both legs showed some significant hypertrophic scars. The left knee joint (acellular ADM grafted site) showed mild contractures, while the right knee joint developed a significant contracture. The "skin" of the co-graft covered site appeared thicker and more elastic. The movement range of the left knee joint was much larger than that of the right knee joint. These results suggest that co-graft of acellular dermal matrix and autogenous microskin may be an effective way to repair this functional site in children with extensive burns and to improve the functional and cosmetic results. PMID:21991120

  19. Wetlands shrinkage, fragmentation and their links to agriculture in the Muleng-Xingkai Plain, China.

    PubMed

    Song, Kaishan; Wang, Zongming; Li, Lin; Tedesco, Lenore; Li, Fang; Jin, Cui; Du, Jia

    2012-11-30

    In the past five decades, the wetlands in the Muleng-Xingkai Plain, Northeast China, have experienced rapid shrinkage and fragmentation. In this study, wetlands cover change and agricultural cultivation were investigated through a time series of thematic maps from 1954, and Landsat satellite images representing the last five decades (1976, 1986, 1995, 2000, and 2005). Wetlands shrinkage and fragmentation were studied based on landscape metrics and the land use changes transition matrix. Furthermore, the driving forces were explored according to socioeconomic development and major natural environmental factors. The results indicate a significant decrease in the wetlands area in the past five decades, with an average annual decrease rate of 9004 ha/yr. Of the 625,268 ha of native wetlands in 1954, approximately 64% has been converted to other land use types by 2005, of which conversion to cropland accounts for the largest share (83%). The number of patches decreased from 1272 (1954) to 197 (1986) and subsequently increased to 326 (2005). The mean patch size changed from 480 ha (1954) to 1521 ha (1976), and then steadily decreased to 574 ha (2005). The largest patch index (total core area index) indicates wetlands shrinkage with decreased values from 31.73 (177,935 ha) to 3.45 (39,421 ha) respectively. Climatic changes occurred over the study period, providing a potentially favorable environment for agricultural development. At the same time population, groundwater harvesting, and fertilizer application increased significantly, resulting in wetlands degradation. According to the results, the shrinkage and fragmentation of wetlands could be explained by socioeconomic development and secondarily aided by changing climatic conditions.

  20. Evolutionary Trajectory of White Spot Syndrome Virus (WSSV) Genome Shrinkage during Spread in Asia

    PubMed Central

    Hemerik, Lia; Vlak, Just M.

    2010-01-01

    Background White spot syndrome virus (WSSV) is the sole member of the novel Nimaviridae family, and the source of major economic problems in shrimp aquaculture. WSSV appears to have rapidly spread worldwide after the first reported outbreak in the early 1990s. Genomic deletions of various sizes occur at two loci in the WSSV genome, the ORF14/15 and ORF23/24 variable regions, and these have been used as molecular markers to study patterns of viral spread over space and time. We describe the dynamics underlying the process of WSSV genome shrinkage using empirical data and a simple mathematical model. Methodology/Principal Findings We genotyped new WSSV isolates from five Asian countries, and analyzed this information together with published data. Genome size appears to stabilize over time, and deletion size in the ORF23/24 variable region was significantly related to the time of the first WSSV outbreak in a particular country. Parameter estimates derived from fitting a simple mathematical model of genome shrinkage to the data support a geometric progression (k<1) of the genomic deletions, with k = 0.371±0.150. Conclusions/Significance The data suggest that the rate of genome shrinkage decreases over time before attenuating. Bioassay data provided support for a link between genome size and WSSV fitness in an aquaculture setting. Differences in genomic deletions between geographic WSSV isolates suggest that WSSV spread did not follow a smooth pattern of geographic radiation, suggesting spread of WSSV over long distances by commercial activities. We discuss two hypotheses for genome shrinkage, an adaptive and a neutral one. We argue in favor of the adaptive hypothesis, given that there is support for a link between WSSV genome size and fitness. PMID:20976239

  1. Lower prolactin levels during cabergoline treatment are associated to tumor shrinkage in prolactin secreting pituitary adenoma.

    PubMed

    Lombardi, M; Lupi, I; Cosottini, M; Rossi, G; Manetti, L; Raffaelli, V; Sardella, C; Martino, E; Bogazzi, F

    2014-12-01

    Dopamine agonists are considered as the first line therapy in prolactin (PRL) secreting pituitary adenomas inducing a normalization of serum PRL and reduction of tumor size. It is known that serum PRL levels, obtained during treatment, are a predictor of tumor shrinkage. Whether PRL suppression below the lower limit of the normal range is related to a greater chance of tumor shrinkage than just its normalization has not been established. This retrospective cohort study was carried out in a tertiary center. Clinical records of 151 patients with PRL-secreting pituitary adenomas (73 micro-, 78 macroadenomas) treated with cabergoline for at least 24 months were analyzed. The adenoma size was analyzed by MRI before and after 24 months of treatment. PRL levels were evaluated every 6 months, assigning a score at each time point (PRL 0 = suppressed; 1 = normal; 2 = above normal). The total score, after 24 months of treatment, was expressed as the sum of the score at each time point and ranged between 0 and 8. A tumor shrinkage was observed in 102/151 patients (67.5%) and it was significantly associated to a lower PRL total score (p = 0.021, OR = 0.85, CI = 0.73-0.97), being significantly more frequent in patients with suppressed PRL than in those with normal PRL (p = 0.045, OR = 0.42, CI = 0.18-0.98) at 24 months. Cabergoline therapy with the goal of achieving PRL levels below the lower limit of normal range can increase the chance to obtain tumor shrinkage of PRL-secreting pituitary adenomas.

  2. Porcine Intestinal Mast Cells. Evaluation of Different Fixatives for Histochemical Staining Techniques Considering Tissue Shrinkage

    PubMed Central

    Rieger, J.; Twardziok, S.; Huenigen, H.; Hirschberg, R.M.; Plendl, J.

    2013-01-01

    Staining of mast cells (MCs), including porcine ones, is critically dependent upon the fixation and staining technique. In the pig, mucosal and submucosal MCs do not stain or stain only faintly after formalin fixation. Some fixation methods are particularly recommended for MC staining, for example the fixation with Carnoy or lead salts. Zinc salt fixation (ZSF) has been reported to work excellently for the preservation of fixation-sensitive antigens. The aim of this study was to establish a reliable histological method for counting of MCs in the porcine intestinum. For this purpose, different tissue fixation and staining methods that also allow potential subsequent immunohistochemical investigations were evaluated in the porcine mucosa, as well as submucosa of small and large intestine. Tissues were fixed in Carnoy, lead acetate, lead nitrate, Zamboni and ZSF and stained subsequently with either polychromatic methylene blue, alcian blue or toluidine blue. For the first time our study reveals that ZSF, a heavy metal fixative, preserves metachromatic staining of porcine MCs. Zamboni fixation was not suitable for histochemical visualization of MCs in the pig intestine. All other tested fixatives were suitable. Alcian blue and toluidine blue co-stained intestinal goblet cells which made a prima facie identification of MCs difficult. The polychromatic methylene blue proved to be the optimal staining. In order to compare MC counting results of the different fixation methods, tissue shrinkage was taken into account. As even the same fixation caused shrinkagedifferences between tissue from small and large intestine, different factors for each single fixation and intestinal localization had to be calculated. Tissue shrinkage varied between 19% and 57%, the highest tissue shrinkage was found after fixation with ZSF in the large intestine, the lowest one in the small intestine after lead acetate fixation. Our study emphasizes that MC counting results from data using different

  3. Na+/K+ pump inhibition induces cell shrinkage in cultured chick cardiac myocytes.

    PubMed

    Smith, T W; Rasmusson, R L; Lobaugh, L A; Lieberman, M

    1993-01-01

    Myocardial cell swelling occurs in ischemia and in reperfusion injury before the onset of irreversible injury. Swelling has been attributed to failure of the Na+/K+ pump and the accumulation of intracellular Na+. To evaluate the role of the pump-leak model of cell volume maintenance, short term changes in cell volume in response to Na+/K+ pump inhibition were studied in aggregates of cultured embryonic chick cardiac myocytes using optical and biochemical methods. Exposure to 100 microM ouabain over 20 min induced cell shrinkage of approximately 10%. Cell water was also decreased by Na+/K+ pump inhibition; incubation for 1 hr either in the presence of 100 microM ouabain or in K(+)-free solution reduced cell water by 18.4% and 28.4% respectively. When exposed to ouabain in the absence of extracellular Ca2+, the aggregates swelled by approximately 15%, indicating that extracellular Ca2+ was required for the ouabain-induced shrinkage to occur. Ouabain still caused shrinkage, however, in the presence of the Ca2+ channel blockers verapamil (10 microM) and nifedipine (10 microM), suggesting that Na+/Ca2+ exchange, rather than Ca2+ channels, is the route for Ca2+ influx during Na+/K+ pump inhibition. Efflux of amino acids (taurine, aspartate, glutamate, glycine and alanine) from confluent monolayers of chick heart cells exposed to ouabain for 20 min was nearly double that observed in control solution. These results suggest that, during Na+/K+ pump inhibition, chick heart cells can limit accumulation of intracellular sodium by means of Na+/Ca2+ exchange, and that a rise in intracellular [Ca2+], also mediated by Na+/Ca2+ exchange, promotes the loss of amino acids and ions to cause cell shrinkage. Therefore, swelling during ischemic injury may not result from Na+/K+ pump failure alone, but may reflect the exhaustion of alternative volume regulatory transport mechanisms.

  4. Autogenic incision and terrace formation resulting from abrupt late-glacial base-level fall, lower Chippewa River, Wisconsin, USA

    NASA Astrophysics Data System (ADS)

    Faulkner, Douglas J.; Larson, Phillip H.; Jol, Harry M.; Running, Garry L.; Loope, Henry M.; Goble, Ronald J.

    2016-08-01

    A paucity of research exists regarding the millennial-scale response of inland alluvial streams to abrupt base-level fall. Studies of modern systems indicate that, over short time scales, the response is a diffusion-like process of upstream-propagating incision. In contrast, evidence from the lower Chippewa River (LCR), located in the upper Midwest of the USA, suggests that autogenic controls operating over time scales of several millennia can overwhelm diffusion, resulting in incision that is prolonged and episodic. During the Last Glacial Maximum, the LCR drained the Chippewa Lobe of the Laurentide Ice Sheet to the glacial upper Mississippi River (UMR). As a meltwater stream, it aggraded and filled its valley with glacial outwash, as did its largest tributaries, which were also meltwater streams. Its nonglacial tributaries aggraded, too, filling their valleys with locally derived sediment. During deglaciation, the UMR incised at least twice, abruptly lowering the LCR's base level - ~ 15 m at 16 ka or earlier and an additional 40 m at ca. 13.4 ka. Each of these base-level falls initiated incision of the LCR, led by upstream migrating knickpoints. The propagation of incision has, however, been a lengthy process. The optically stimulated luminescence (OSL) ages of terrace alluvium indicate that, by 13.5 ka, incision had advanced up the LCR only 15 km, and by 9 ka, only 55 km. The process has also been episodic, resulting in the formation of fill-cut terraces (inferred from GPR surveys and exposures of terrace alluvium) that are younger and more numerous in the upstream direction. Autogenic increases in sediment load and autogenic bed armoring, the result of periodic tributary-stream rejuvenation and preferential winnowing of fines by the incising river, may have periodically caused knickpoint migration and incision to slow and possibly stop, allowing lateral erosion and floodplain formation to dominate. A decline in sediment flux from stabilizing incised tributary

  5. Polygon/Cracked Sedimentary Rock

    NASA Technical Reports Server (NTRS)

    2004-01-01

    4 December 2004 Exposures of sedimentary rock are quite common on the surface of Mars. Less common, but found in many craters in the regions north and northwest of the giant basin, Hellas, are sedimentary rocks with distinct polygonal cracks in them. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from the floor of an unnamed crater near 21.0oS, 311.9oW. Such cracks might have formed by desiccation as an ancient lake dried up, or they might be related to ground ice freeze/thaw cycles or some other stresses placed on the original sediment or the rock after it became lithified. The 300 meter scale bar is about 328 yards long. The scene is illuminated by sunlight from the upper left.

  6. Biaxial Fatigue Cracking from Notch

    DTIC Science & Technology

    2013-03-04

    Leevers (reference 11) noticed that the variation in  from 0 to 2 has little effect on the da/dN in PVC ( polyvinyl - chloride ), but reduces the da/dN...under biaxial rotating and bending. Ahmad (reference 2) formulated a model for the biaxial fatigue crack growth in aggressive environment, outlined by...1962, Vol. 90, pp. 238-239. 20. ASM Handbook , Vol. 12 Fractography: 1992, p. 430, 438. 21. Metals Handbook , Vol. 9 Fractography and Atlas of

  7. A Study of Shrinkage Stress Reduction and Mechanical Properties of Nanogel-Modified Resin Systems.

    PubMed

    Liu, Jiancheng; Howard, Gregory D; Lewis, Steven H; Barros, Matthew D; Stansbury, Jeffrey W

    2012-11-01

    A series of nanogel compositions were prepared from urethane dimethacrylate (UDMA) and isobornyl methacrylate (IBMA) in the presence of a thiol chain transfer agent. The linear oligomer of IBMA was synthesized by a similar solution polymerization technique. The nanogels were prepared with different crosslinker concentrations to achieve varied branching densities and molecular weights. The prepolymers were dispersed in triethylene glycol dimethacrylate at loading levels ranging from 10 wt% to 50 wt%. Photopolymerization reaction kinetics of all prepolymer modified systems were enhanced relative to the nanogel-free control during early stage polymerization while limiting conversion was similar for most samples. Volumetric polymerization shrinkage was reduced proportionally with the prepolymer content while the corresponding decrease in polymerization stress was potentially greater than an additive linear behavior. Flexural strength for inert linear polymer-modified systems decreased significantly with the increase in the prepolymer content; however, with an increase in the crosslinker concentration within the nanogel additives, and an increase in the concentration of residual pendant reactive sites, flexural strength was maintained or improved regardless of the nanogel loading level. This demonstrates that covalent attachment rather than just physical entanglement with the polymer matrix is important for effective polymer mechanical reinforcement by nanogel additives. Reactive nanogel additives can be considered as a practical, generic means to achieve substantial reductions in polymerization shrinkage and shrinkage stress in common polymers.

  8. Evaluation of polymerization shrinkage of dental composites by an optical method.

    PubMed

    Weig, K M; Magalhães Filho, T R; Costa Neto, C A; Costa, M F

    2015-02-01

    This study proposes an alternative methodology for evaluating polymerization shrinkage of dental composites using an advanced video extensometer (AVE) system. This equipment measures the displacement between two points drawn on a tooth's wall without requiring physical contact with the tooth. By doing so, the polymerization process was monitored by the cusp deflection. This technique was used in human and bovine teeth, where the cavities were prepared under controlled conditions so that the volume of the composite used was the same in both types of teeth. After the cavity preparation, the specimens were acid etched, washed and dried, and then the adhesive was applied and polymerized. The composite was then inserted into the cavity. Polymerization was performed with two different light polymerizing units (LD Max and Optilight Max - Gnatus do Brasil), and the displacement curve of the tooth cusp was recorded for a period of 400 s. After a statistical analysis, it was concluded that the technique was capable of evaluating shrinkage by the deflection from the cusps and that the human and bovine teeth do not react in a similar manner towards the polymerization shrinkage of composites.

  9. Multiple-Shrinkage Multinomial Probit Models with Applications to Simulating Geographies in Public Use Data

    PubMed Central

    Burgette, Lane F.; Reiter, Jerome P.

    2013-01-01

    Multinomial outcomes with many levels can be challenging to model. Information typically accrues slowly with increasing sample size, yet the parameter space expands rapidly with additional covariates. Shrinking all regression parameters towards zero, as often done in models of continuous or binary response variables, is unsatisfactory, since setting parameters equal to zero in multinomial models does not necessarily imply “no effect.” We propose an approach to modeling multinomial outcomes with many levels based on a Bayesian multinomial probit (MNP) model and a multiple shrinkage prior distribution for the regression parameters. The prior distribution encourages the MNP regression parameters to shrink toward a number of learned locations, thereby substantially reducing the dimension of the parameter space. Using simulated data, we compare the predictive performance of this model against two other recently-proposed methods for big multinomial models. The results suggest that the fully Bayesian, multiple shrinkage approach can outperform these other methods. We apply the multiple shrinkage MNP to simulating replacement values for areal identifiers, e.g., census tract indicators, in order to protect data confidentiality in public use datasets. PMID:24358073

  10. Large-proportional shrunken bio-replication of shark skin based on UV-curing shrinkage

    NASA Astrophysics Data System (ADS)

    Chen, Huawei; Che, Da; Zhang, Xin; Yue, Yue; Zhang, Deyuan

    2015-01-01

    The shark skin effect has attracted worldwide attention because of its superior drag reduction. As the product of natural selection, the maximum drag reduction of shark skin is found in its normal living environment. Large-proportional shrinkage of shark skin morphology is greatly anticipated for its adaptation to faster fluid flow. One novel approach, large-proportional shrunken bio-replication, is proposed as a method to adjust the optimal drag reduction region of shark skin based on the shrinkage of UV-cured material. The shark skin is taken as a replica template to allow large-proportional shrinking in the drag reduction morphology by taking advantage of the shrinkage of UV-curable material. The accuracy of the large-proportional shrunken bio-replication approach is verified by a comparison between original and shrunken bio-replicated shark skin, which shows that the shrinking ratio can reach 23% and the bio-replication accuracy is higher than 95%. In addition, the translation of the optimum drag reduction peak of natural surface function to various applications and environments is proved by drag reduction experiments.

  11. Shrinkage covariance matrix approach based on robust trimmed mean in gene sets detection

    NASA Astrophysics Data System (ADS)

    Karjanto, Suryaefiza; Ramli, Norazan Mohamed; Ghani, Nor Azura Md; Aripin, Rasimah; Yusop, Noorezatty Mohd

    2015-02-01

    Microarray involves of placing an orderly arrangement of thousands of gene sequences in a grid on a suitable surface. The technology has made a novelty discovery since its development and obtained an increasing attention among researchers. The widespread of microarray technology is largely due to its ability to perform simultaneous analysis of thousands of genes in a massively parallel manner in one experiment. Hence, it provides valuable knowledge on gene interaction and function. The microarray data set typically consists of tens of thousands of genes (variables) from just dozens of samples due to various constraints. Therefore, the sample covariance matrix in Hotelling's T2 statistic is not positive definite and become singular, thus it cannot be inverted. In this research, the Hotelling's T2 statistic is combined with a shrinkage approach as an alternative estimation to estimate the covariance matrix to detect significant gene sets. The use of shrinkage covariance matrix overcomes the singularity problem by converting an unbiased to an improved biased estimator of covariance matrix. Robust trimmed mean is integrated into the shrinkage matrix to reduce the influence of outliers and consequently increases its efficiency. The performance of the proposed method is measured using several simulation designs. The results are expected to outperform existing techniques in many tested conditions.

  12. Hygroscopic swelling and shrinkage of latewood cell wall micropillars reveal ultrastructural anisotropy.

    PubMed

    Rafsanjani, Ahmad; Stiefel, Michael; Jefimovs, Konstantins; Mokso, Rajmund; Derome, Dominique; Carmeliet, Jan

    2014-06-06

    We document the hygroscopic swelling and shrinkage of the central and the thickest secondary cell wall layer of wood (named S2) in response to changes in environmental humidity using synchrotron radiation-based phase contrast X-ray tomographic nanoscopy. The S2 layer is a natural fibre-reinforced nano-composite polymer and is strongly reactive to water. Using focused ion beam, micropillars with a cross section of few micrometres are fabricated from the S2 layer of the latewood cell walls of Norway spruce softwood. The thin neighbouring cell wall layers are removed to prevent hindering or restraining of moisture-induced deformation during swelling or shrinkage. The proposed experiment intended to get further insights into the microscopic origin of the anisotropic hygro-expansion of wood. It is found that the swelling/shrinkage strains are highly anisotropic in the transverse plane of the cell wall, larger in the normal than in the direction parallel to the cell wall's thickness. This ultrastructural anisotropy may be due to the concentric lamellation of the cellulose microfibrils as the role of the cellulose microfibril angle in the transverse swelling anisotropy is negligible. The volumetric swelling of the cell wall material is found to be substantially larger than the one of wood tissues within the growth ring and wood samples made of several growth rings. The hierarchical configuration in wood optimally increases its dimensional stability in response to a humid environment with higher scales of complexity.

  13. Hygroscopic swelling and shrinkage of latewood cell wall micropillars reveal ultrastructural anisotropy

    PubMed Central

    Rafsanjani, Ahmad; Stiefel, Michael; Jefimovs, Konstantins; Mokso, Rajmund; Derome, Dominique; Carmeliet, Jan

    2014-01-01

    We document the hygroscopic swelling and shrinkage of the central and the thickest secondary cell wall layer of wood (named S2) in response to changes in environmental humidity using synchrotron radiation-based phase contrast X-ray tomographic nanoscopy. The S2 layer is a natural fibre-reinforced nano-composite polymer and is strongly reactive to water. Using focused ion beam, micropillars with a cross section of few micrometres are fabricated from the S2 layer of the latewood cell walls of Norway spruce softwood. The thin neighbouring cell wall layers are removed to prevent hindering or restraining of moisture-induced deformation during swelling or shrinkage. The proposed experiment intended to get further insights into the microscopic origin of the anisotropic hygro-expansion of wood. It is found that the swelling/shrinkage strains are highly anisotropic in the transverse plane of the cell wall, larger in the normal than in the direction parallel to the cell wall's thickness. This ultrastructural anisotropy may be due to the concentric lamellation of the cellulose microfibrils as the role of the cellulose microfibril angle in the transverse swelling anisotropy is negligible. The volumetric swelling of the cell wall material is found to be substantially larger than the one of wood tissues within the growth ring and wood samples made of several growth rings. The hierarchical configuration in wood optimally increases its dimensional stability in response to a humid environment with higher scales of complexity. PMID:24671938

  14. A Study of Shrinkage Stress Reduction and Mechanical Properties of Nanogel-Modified Resin Systems

    PubMed Central

    Liu, JianCheng; Howard, Gregory D.; Lewis, Steven H.; Barros, Matthew D.; Stansbury, Jeffrey W.

    2012-01-01

    A series of nanogel compositions were prepared from urethane dimethacrylate (UDMA) and isobornyl methacrylate (IBMA) in the presence of a thiol chain transfer agent. The linear oligomer of IBMA was synthesized by a similar solution polymerization technique. The nanogels were prepared with different crosslinker concentrations to achieve varied branching densities and molecular weights. The prepolymers were dispersed in triethylene glycol dimethacrylate at loading levels ranging from 10 wt% to 50 wt%. Photopolymerization reaction kinetics of all prepolymer modified systems were enhanced relative to the nanogel-free control during early stage polymerization while limiting conversion was similar for most samples. Volumetric polymerization shrinkage was reduced proportionally with the prepolymer content while the corresponding decrease in polymerization stress was potentially greater than an additive linear behavior. Flexural strength for inert linear polymer-modified systems decreased significantly with the increase in the prepolymer content; however, with an increase in the crosslinker concentration within the nanogel additives, and an increase in the concentration of residual pendant reactive sites, flexural strength was maintained or improved regardless of the nanogel loading level. This demonstrates that covalent attachment rather than just physical entanglement with the polymer matrix is important for effective polymer mechanical reinforcement by nanogel additives. Reactive nanogel additives can be considered as a practical, generic means to achieve substantial reductions in polymerization shrinkage and shrinkage stress in common polymers. PMID:23109731

  15. DH and ESPI laser interferometry applied to the restoration shrinkage assessment

    NASA Astrophysics Data System (ADS)

    Campos, L. M. P.; Parra, D. F.; Vasconcelos, M. R.; Vaz, M.; Monteiro, J.

    2014-01-01

    In dental restoration postoperative marginal leakage is commonly associated to polymerization shrinkage effects. In consequence the longevity and quality of restorative treatment depends on the shrinkage mechanisms of the composite filling during the polymerization. In this work the development of new techniques for evaluation of those effects under light-induced polymerization of dental nano composite fillings is reported. The composite resins activated by visible light, initiate the polymerization process by absorbing light in wavelengths at about 470 nm. The techniques employed in the contraction assessment were digital holography (DH) and Electronic Speckle Pattern Interferometry (ESPI) based on laser interferometry. A satisfactory resolution was achieved in the non-contact displacement field measurements on small objects concerning the experimental dental samples. According to a specific clinical protocol, natural teeth were used (human mandibular premolars). A class I cavity was drilled and restored with nano composite material, according to Black principles. The polymerization was monitored by DH and ESPI in real time during the cure reaction of the restoration. The total displacement reported for the material in relation of the tooth wall was 3.7 μm (natural tooth). The technique showed the entire tooth surface (wall) deforming during polymerization shrinkage.

  16. Evidence for the correcting-mechanism explanation of the Kanizsa amodal shrinkage.

    PubMed

    Mitsudo, Hiroyuki; Nakamizo, Sachio

    2005-01-01

    An object phenomenally shrinks in its horizontal dimension when shown on a 2-D plane as if the central portion of the object were partially occluded by another vertical one in 3-D space (the Kanizsa amodal shrinkage). We examined the predictions of the correcting-mechanism hypothesis proposed by Ohtsuka and Ono (2002, Proceedings of SPIE 4864 167-174), which states that an inappropriate operation of the mechanism that corrects a phenomenal increase in monocularly visible areas accompanied by a stereoscopic occluder gives rise to the illusion. In this study we measured the perceived width (or height in experiment 3) of a square seen behind a rectangle, while controlling other factors which potentially influence the illusion, such as the division of space or depth stratification. The results of five experiments showed that (a) the perceived width was not influenced when the occluder had a relatively large binocular disparity, but was underestimated when the occluder did not have disparity, and (b) the shrinkage diminished when the foreground rectangle was transparent, was horizontally oriented, or contained no pictorial occlusion cues. These results support the hypothesis that the correcting mechanism, triggered by pictorial occlusion cues, contributes to the Kanizsa shrinkage.

  17. Identification of signalling cascades involved in red blood cell shrinkage and vesiculation

    PubMed Central

    Kostova, Elena B.; Beuger, Boukje M.; Klei, Thomas R.L.; Halonen, Pasi; Lieftink, Cor; Beijersbergen, Roderick; van den Berg, Timo K.; van Bruggen, Robin

    2015-01-01

    Even though red blood cell (RBC) vesiculation is a well-documented phenomenon, notably in the context of RBC aging and blood transfusion, the exact signalling pathways and kinases involved in this process remain largely unknown. We have established a screening method for RBC vesicle shedding using the Ca2+ ionophore ionomycin which is a rapid and efficient method to promote vesiculation. In order to identify novel pathways stimulating vesiculation in RBC, we screened two libraries: the Library of Pharmacologically Active Compounds (LOPAC) and the Selleckchem Kinase Inhibitor Library for their effects on RBC from healthy donors. We investigated compounds triggering vesiculation and compounds inhibiting vesiculation induced by ionomycin. We identified 12 LOPAC compounds, nine kinase inhibitors and one kinase activator which induced RBC shrinkage and vesiculation. Thus, we discovered several novel pathways involved in vesiculation including G protein-coupled receptor (GPCR) signalling, the phosphoinositide 3-kinase (PI3K)–Akt (protein kinase B) pathway, the Jak–STAT (Janus kinase–signal transducer and activator of transcription) pathway and the Raf–MEK (mitogen-activated protein kinase kinase)–ERK (extracellular signal-regulated kinase) pathway. Moreover, we demonstrated a link between casein kinase 2 (CK2) and RBC shrinkage via regulation of the Gardos channel activity. In addition, our data showed that inhibition of several kinases with unknown functions in mature RBC, including Alk (anaplastic lymphoma kinase) kinase and vascular endothelial growth factor receptor 2 (VEGFR-2), induced RBC shrinkage and vesiculation. PMID:25757360

  18. Hysteresis from Multiscale Porosity: Modeling Water Sorption and Shrinkage in Cement Paste

    NASA Astrophysics Data System (ADS)

    Pinson, Matthew B.; Masoero, Enrico; Bonnaud, Patrick A.; Manzano, Hegoi; Ji, Qing; Yip, Sidney; Thomas, Jeffrey J.; Bazant, Martin Z.; Van Vliet, Krystyn J.; Jennings, Hamlin M.

    2015-06-01

    Cement paste has a complex distribution of pores and molecular-scale spaces. This distribution controls the hysteresis of water sorption isotherms and associated bulk dimensional changes (shrinkage). We focus on two locations of evaporable water within the fine structure of pastes, each having unique properties, and we present applied physics models that capture the hysteresis by dividing drying and rewetting into two related regimes based on relative humidity (RH). We show that a continuum model, incorporating a pore-blocking mechanism for desorption and equilibrium thermodynamics for adsorption, explains well the sorption hysteresis for a paste that remains above approximately 20% RH. In addition, we show with molecular models and experiments that water in spaces of ≲1 nm width evaporates below approximately 20% RH but reenters throughout the entire RH range. This water is responsible for a drying shrinkage hysteresis similar to that of clays but opposite in direction to typical mesoporous glass. Combining the models of these two regimes allows the entire drying and rewetting hysteresis to be reproduced accurately and provides parameters to predict the corresponding dimensional changes. The resulting model can improve the engineering predictions of long-term drying shrinkage accounting also for the history dependence of strain induced by hysteresis. Alternative strategies for quantitative analyses of the microstructure of cement paste based on this mesoscale physical model of water content within porous spaces are discussed.

  19. Crack, sex work, and HIV.

    PubMed

    Leggett, T

    1999-01-01

    South Africa's long isolation, and perhaps deliberate efforts by the apartheid government, have led to an unusual pattern of drug abuse in the country. Drugs not commonly used in other countries, such as Mandrax and Welconol, are widespread in South Africa, while the street drugs commonly found in other countries, such as cocaine and heroin, have been relatively rare. However, this is changing, as international drug traffickers now import a broad range of drugs, including heroin and cocaine. Demand for these drugs has been established in South Africa, including among the urban lower classes. Immigration, especially of other Africans and particularly Nigerians, has accelerated the trend. While both mandrax and crack cocaine are smoked, the former is a sedative and the latter is a stimulant with pro-sexual effects. These sexual effects, together with very strong addictive potential, have led to very high HIV seroprevalence in user populations. Addiction often leads female users into prostitution, with prostitutes being a prime conduit for the spread of both the drug and HIV infection. Desperate to earn funds to meet their crack consumption needs, drug-addicted female prostitutes in South Africa service many clients and engage in practices shunned by their nonaddicted peers, such as unprotected and anal sex. There will be serious long-term effects of crack cocaine consumption, together with prostitution, upon all of South African society.

  20. The Origin of Griffith Cracks

    NASA Astrophysics Data System (ADS)

    Campbell, John

    2011-12-01

    As a result of the extremely strong interatomic bonds, pores and cracks are difficult to form in metals. They seem unlikely to be created intrinsically by the normal mechanisms involved in the formation of a solid by solidification from liquid, or condensation from vapor phases, or probably, by lattice mechanisms in the solid state. It is proposed here that initiation sites for pores and cracks for most failures of metals can only be initiated from unbonded interfaces. Such unbonded defects are introduced into metals only via extrinsic ( entrainment) mechanisms resulting from production processes, particularly melting and casting. Only entrained inclusions, particularly bifilms, have unbonded interfaces that can be opened to constitute Griffith cracks and can explain the initiation of macroscopic fracture and related microscopic processes, such as a decohesion between the second phases and a matrix. In the absence of entrained defects, metals would be predicted to fail in tension only either (1) at high stresses probably in excess of 20 GPa or (2) by ductile flow to the point of 100 pct reduction in area. Improved melting and casting processes giving freedom from entrained defects promise unprecedented performance and reliability of engineering metals.