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Sample records for comparative experimental study

  1. It Pays to Compare: An Experimental Study on Computational Estimation

    ERIC Educational Resources Information Center

    Star, Jon R.; Rittle-Johnson, Bethany

    2009-01-01

    Comparing and contrasting examples is a core cognitive process that supports learning in children and adults across a variety of topics. In this experimental study, we evaluated the benefits of supporting comparison in a classroom context for children learning about computational estimation. Fifth- and sixth-grade students (N = 157) learned about…

  2. HRTEM study comparing naturally and experimentally weathered pyroxenoids

    SciTech Connect

    Banfield, J.F.; Ferruzzi, G.G.; Casey, W.H.; Westrich, H.R.

    1995-01-01

    The mineralogy and chemistry of both naturally and experimentally weathered MnSiO{sub 3} chain silicate minerals (rhodonite and pyroxmangite) were compared. In natural MnSiO{sub 3}, high-resolution transmission-electron microscope observations reveal that alteration begins at grain boundaries and planar defects parallel to the silicate chains that represent junctions between regions with different chain periodicities. Dissolution along these defects results in elongate etch pits that may be partly filled by smectite. Smectite (Ca{sub 0.3}Mn{sub 2}Zn{sub 0.4}Al{sub 0.1}Si{sub 4}O{sub 10}(OH){sub 2}) also develops in larger etches at grain boundaries. The Zn apparently released by weathering of coexisting sphalerite, may facilitate crystallization of manganese-smectite; rhodochrosite is also an initial product. X-ray diffraction patterns from highly altered materials reveal only rhodochrosite and quartz. Simplified reactions are H{sub 2}CO{sub 3}(aq) + 4 MnSiO{sub 3}(s) = Mn{sub 3}Si{sub 4}O{sub 10}(OH){sub 2}(s) + MnCO{sub 3}(s) accompanied by 3H{sub 2}CO{sub 3}(aq) + Mn{sub 3}Si{sub 4}O{sub 10}(OH){sub 2}(s) = 3 MnCO{sub 3}(s) + 4SiO{sub 2}(s) + 4H{sub 2}O. Pyroxenoid dissolution is incongruent under experimental conditions. A 3-7 nm-thick layer of amorphous silica is present at the mineral surface after {approximately}2000 h of reaction in acidic and near-neutral pH solutions that were undersaturated with respect to bulk amorphous silica. This thin layer of polymeric silica, which is absent on unreacted grains, is interpreted to have formed largely by incongruent dissolution at the mineral surface as protons in solution rapidly exchange for near-surface Mn. The layer may also contain silica readsorbed back onto the surface from solution. The net result is that silica from the pyroxenoid is redistributed directly into reaction products. Upon aging in air for a year, leached layers partially recrystallize.

  3. Osseointegration of alumina bioceramic granules: A comparative experimental study

    NASA Astrophysics Data System (ADS)

    Rerikh, V. V.; Avetisyan, A. R.; Zaydman, A. M.; Anikin, K. A.; Bataev, V. A.; Nikulina, A. A.; Sadovoy, M. A.; Aronov, A. M.; Semantsova, E. S.

    2016-08-01

    To perform a comparative analysis of osseointegration of bioceramic alumina-based granules, hydroxyapatite-based granules, and deproteinized bone granules. The experiment was conducted on 52 adult male Kyoto-Wistar rats weighing 350 to 520 g. The animals were divided into five matched groups that differed only in the type of an implanted material. The granules were implanted in the lumbar vertebral bodies and in the distal right femur of each laboratory animal. Two months after surgery, the animals were euthanized, followed by tissue sampling for morphological studies. An examination of specimens from the groups with implanted alumina granules revealed the newly formed trabecular bone with remodeling signs. The bone tissue filled the intragranular space, tightly adhering to the granule surface. There was no connective tissue capsule on the border between bone tissue and alumina granules. Cylindrical bioceramic alumina-based granules with an open internal channel have a higher strength surpassing than that of analogs and the osseointegration ability close to that of hydroxyapatite and deproteinized bone granules.

  4. Thought-shape fusion in anorexia and bulimia nervosa: a comparative experimental study.

    PubMed

    Kostopoulou, Myrsini; Varsou, Eleftheria; Stalikas, Anastassios

    2013-09-01

    'Thought-shape fusion' (TSF) is a cognitive distortion specific in patients with eating disorders and occurs when the thought about eating a forbidden food increases a person's estimate of her weight/shape, elicits a perception of moral wrongdoing and makes her feel fat. This study aimed to experimentally induce, study and compare TSF between patients with bulimia nervosa (BN) and patients with anorexia nervosa (AN). 31 patients diagnosed with a current eating disorder, of which 20 met DSM-IV-TR criteria for BN and 11 for AN, participated in a mixed-model experimental design with the aim of eliciting TSF and investigating the effects of corrective behaviors (checking and mental neutralizing). Verbal analogue scales constituted the main outcome measures. TSF was experimentally induced and expressed in a similar way in both clinical groups, apart from 'feeling fat' which was higher in BN patients. TSF induction triggered heightened levels of anxiety, guilt and urges to engage in corrective behaviors in both groups. Body dissatisfaction only increased in the BN patients. Mental neutralizing and to a lesser extent checking reduced most effects of the experimental procedure, but this effect was larger for BN patients. The nature of TSF seems to have similarities between BN and AN patients; however, the precise connection between TSF and different types of eating disorders remains to be explored in future clinical trials. PMID:23881747

  5. Comparative Experimental Study of Wound Healing in Mice: Pelnac versus Integra

    PubMed Central

    Wosgrau, Ana Carolina Câmara; Jeremias, Talita da Silva; Leonardi, Dilmar Francisco; Pereima, Maurício José; Di Giunta, Gabriella; Trentin, Andrea Gonçalves

    2015-01-01

    Strategies for skin regeneration have been developed to provide effective treatment for cutaneous wounds and disease. Dermal substitutes have been used to cover the lesion to facilitate cell colonization, thereby promoting dermal regeneration. However, very little is known about Pelnac matrix especially at histological level. Therefore, the present work carried out an experimental in vivo comparative analysis between Pelnac and Integra, the most used dermal templates, in a mouse model of full-thickness skin wounds. Histological sections performed at the 3rd, 6th and 9th days after surgery were analyzed with regard to inflammatory response and vascularization. Both templates were completely incorporated in all animals at the end of the analyzed period. Pelnac-treated animals displayed reduced granulation tissue during the first 6 days of treatment compared to the animals treated with Integra at the same time period. The number of inflammatory cells (neutrophils) was similar in both groups during the period, significantly reducing at the end of inflammatory phase (9th day of treatment) consistent with the progression of healing process. In addition, the density of blood vessels was also statistically similar in both matrices. Therefore, the two dermal templates displayed comparable biological behavior in tissue repair. It is noteworthy that this is the first experimental study comparing Pelnac and Integra dermal templates with focus on full-thickness skin wounds. PMID:25798623

  6. Bioactive glass in cavitary bone defects: a comparative experimental study in rabbits

    PubMed Central

    Camargo, André Ferrari de França; Baptista, André Mathias; Natalino, Renato; de Camargo, Olavo Pires

    2015-01-01

    OBJECTIVES: To compare bioactive glass and autograft regarding their histomorphometric characteristics. METHODS: The authors conducted a prospective case-control experimental study on animals in order to compare the histomorphometric characteristics of bioactive glass versus autograft. Eight rabbits underwent surgery in which a cavitary defect was created in both proximal femurs. One side was filled with bioactive glass granules and the other, with autograft grafted from the contralateral side. The sides were randomized. Fourteen days after surgery, the animals were euthanized. RESULTS: Histologic analysis revealed that bone neoformation was equivalent among the two groups and the osteoblasts cell-count was higher in the femurs treated with bioactive glass. The osteocytes cell-count, however, was lower. The similarity in bone formation between both groups was consistent to literature findings. CONCLUSION: Bioactive glass is similar to autograft regarding bone neoformation in this animal model of cavitary bone defects. Level of Evidence III, Case-Control Study. PMID:26327802

  7. Comparative experimental biomechanical study of different types of stabilization methods of the lower cervical spine.

    PubMed

    Kalff, R; Ulrich, C; Claes, L; Wilke, H J; Grote, W

    1992-01-01

    In a comparative experimental biodynamic study using thirty-two human cervical spines of cadavers the primary stabilization effect of different types of spondylodesis was examined. Whereas in flexion stress all methods showed a sufficient stability, the rotation tests proved, that in case of a dorsal instability of the lower cervical spine, posterior interlaminar wiring or anterior plate stabilization showed no reliable stabilization effect. However, the compression clamps by ROOSEN and TRAUSCHEL as well as the hook-plates by MAGERL are suitable dorsal stabilization methods with excellent rotation stability. In case of dorsal instability of the lower cervical spine a posterior spondylodesis is necessary and sufficient. PMID:1480272

  8. A study of Ti-doped WO3 thin films using comparative theoretical and experimental approach

    NASA Astrophysics Data System (ADS)

    Paez, Aurelio

    Metal oxides like Tungsten Oxide (WO3) are well documented and characterized in the literature, with uses in darkening windows and mirrors, flat computer displays, solar panel cooling, and sensors (of interest in this study). Ti doping of WO3 is less documented and the focus of this study. Sample thin films of pure WO3 and varyingly Ti doped WO3 were prepared using Radio Frequency magnetron sputtering (RF) (13.56 MHz) to grow thin films on a silicon substrate. This study aims to compare multiple Ti doping percentages in WO3 theoretically and then compare with experimental data taken from thin films of various Ti doping levels grown at temperatures ranging from room temperature to 400 0°C. Characterization of the materials was to be conducted using Fourier Transform Infrared Spectroscopy, Raman Spectroscopy, X-ray diffraction, and other theoretical and simulated approaches. Theoretical calculations optimized Ti doping at somewhere between 6.25% and 12%. Experimental data indicates that under the given growing conditions optimal Ti doping is 5%. The percentage of Ti may be able to be increased and the material retain desired characteristics with an increased growth temperature above 400 0°C as annealing samples post-growth has no positive impact on the thin film structure.

  9. Mass attenuation coefficients of composite materials by Geant4, XCOM and experimental data: comparative study

    NASA Astrophysics Data System (ADS)

    Medhat, M. E.; Singh, V. P.

    2014-09-01

    The main goal of this present study is focused on testing the applicability of Geant4 electromagnetic models for studying mass attenuations coefficients for different types of composite materials at 59.5, 80, 356, 661.6, 1173.2 and 1332.5 keV photon energies. The simulated results of mass attenuation coefficients were compared with the experimental and theoretical XCOM data for the same samples and a good agreement has been observed. The results indicate that this process can be followed to determine the data on the attenuation of gamma rays with the several energies in different materials. The modeling for photon interaction parameters was standard for any type of composite samples. The Geant4 code can be utilized for gamma ray attenuation coefficients for the sample at different energies, which may sometimes be impractical by experiment investigation.

  10. Crystalline and Spectroscopic Experimental Study of the Dinitromesithylen (DNM) Compared with the Theoretical Results

    NASA Astrophysics Data System (ADS)

    Brihi, O.; Medjroubi, M. L.; Hamdouni, N.; Meinnel, J.; Boucekkine, A.; Boudjada, A.

    The aim by our group is to understand the behaviour of the grouping methyl starting from the study of molecules having a great symmetry. In this part of work, it is had the crystalline structure of the dinitromesitylen (DNM) who is solved starting from the diffraction of x-rays starting from a monocrystal at the ambient temperature. Parallel to the experimental study, we undertook theoretical calculations conformation of the insulated molecule of DNM by using the methods of the DFT (Density Functional Theory).Calculations of optimization of the molecular conformation of the DNM by using the chain of program GAUSSIAN03 and functional MPW1PW91, B3LYP level with the 6-311G and LANL2DZ bases gave a conformation Cs with results very close to the experiment for the lengths and the angles of bond. The computation results obtained starting from the base set (6-311G) and functional MPW1PW91 give for the conformation of Dinitromesitylen (DNM) a good agreement of about a 1.9% for the lengths of bond and 1.2% for the angles of bond compared with the results of the diffraction of x-rays. Calculations of Raman and infra-red spectroscopy undertaken starting from the results of optimization by using same functional MPW1PW91 and B3LYP and the sets of bases 6-311G LanL2DZ led to the values of frequencies very close to the experimental results.

  11. Evaluation of an experimental rat model for comparative studies of bleaching agents

    PubMed Central

    Cintra, Luciano Tavares Angelo; Benetti, Francine; Ferreira, Luciana Lousada; Rahal, Vanessa; Ervolino, Edilson; Jacinto, Rogério de Castilho; Gomes, João Eduardo; Briso, André Luiz Fraga

    2016-01-01

    ABSTRACT Dental materials, in general, are tested in different animal models prior to their clinical use in humans, except for bleaching agents. Objectives To evaluate an experimental rat model for comparative studies of bleaching agents by investigating the influence of different concentrations and application times of H2O2 gel in the pulp tissue during in-office bleaching of rats’ vital teeth. Material and methods The right and left maxillary molars of 50 Wistar rats were bleached with 20% and 35% H2O2 gels, respectively, for 5, 10, 15, 30, or 45 min (n=10 rats/group). Ten animals (control) were untreated. The rats were killed after 2 or 30 days, and the maxillae were examined by light microscopy. Inflammation was evaluated by histomorphometric analysis with inflammatory cell counting in the coronal and radicular thirds of the pulp. The counting of fibroblasts was also performed. Scores were attributed to the odontoblastic layer and to vascular changes. The tertiary dentin area and the pulp chamber central area were histomorphometrically measured. Data were compared by the analysis of variance and the Kruskal-Wallis test (p<0.05). Results After 2 days, the amount of inflammatory cells increased in the occlusal third of the coronal pulp until the time of 15 min for both concentrations of bleaching gels. In 30 and 45 min groups of each concentration, the number of inflammatory cells decreased along with the appearance of necrotic areas. After 30 days, a reduction in the pulp chamber central area and an enlargement of tertiary dentin area were observed without the detection of inflammation areas. Conclusion The rat model of extra coronal bleaching showed to be adequate for bleaching protocols studies, as it was possible to observe alterations in the pulp tissues and in the tooth structure caused by different concentrations and periods of application of bleaching agents. PMID:27008262

  12. Evaluation of an experimental rat model for comparative studies of bleaching agents

    PubMed Central

    CINTRA, Luciano Tavares Angelo; BENETTI, Francine; FERREIRA, Luciana Louzada; RAHAL, Vanessa; ERVOLINO, Edilson; JACINTO, Rogério de Castilho; GOMES, João Eduardo; BRISO, André Luiz Fraga

    2016-01-01

    ABSTRACT Dental materials in general are tested in different animal models prior to the clinical use in humans, except for bleaching agents. Objectives To evaluate an experimental rat model for comparative studies of bleaching agents, by investigating the influence of different concentrations and application times of H2O2 gel in the pulp tissue during in-office bleaching of rats’ vital teeth. Material and Methods The right and left maxillary molars of 50 Wistar rats were bleached with 20% and 35% H2O2 gels, respectively, for 5, 10, 15, 30, or 45 min (n=10 rats/group). Ten animals were untreated (control). The rats were killed after 2 or 30 days, and the maxillae were examined by light microscopy. Inflammation was evaluated through histomorphometric analysis with inflammatory cell count in the coronal and radicular thirds of the pulp. Fibroblasts were also counted. Scores were attributed to odontoblastic layer and vascular changes. Tertiary dentin area and pulp chamber central area were measured histomorphometrically. Data were compared by analysis of variance and Kruskal-Wallis test (p<0.05). Results After 2 days, the amount of inflammatory cells increased in the coronal pulp occlusal third up to the 15-min application groups of each bleaching gel. In the groups exposed to each concentration for 30 and 45 min, the number of inflammatory cells decreased along with the appearance of necrotic areas. After 30 days, reduction on the pulp chamber central area and enlargement of the tertiary dentin area were observed, without the detection of inflammation areas. Conclusion The rat model of extracoronal bleaching showed to be adequate for studies of bleaching protocols, as it was possible to observe alterations in the pulp tissues and tooth structure caused by different concentrations and application periods of bleaching agents. PMID:27119766

  13. Compared Experimental Studies of Giant Vesicles and Red Blood Cells in Shear Flow

    NASA Astrophysics Data System (ADS)

    Viallat, Annie; Faivre, Magalie; Leyrat, Anne; Abkarian, Manouk

    2003-11-01

    The motion and the deformation of soft shells in bounded shear flows is of biological importance since, for example, white or red blood cells (RBC) are submitted to strong shear stresses during circulation. The role of cell deformability and viscoelastic properties has not been yet quantitatively studied experimentally although it is important for understanding mobility, binding and rolling of cells on vascular walls. We quantitatively characterized the behaviour of giant lipid vesicles and RBC in a bounded linear shear flow by optical microscopy. The tank-treading motion (fixed cell orientation), the tumbling motion and the lift force experienced by deformable vesicles and RBC close to a substrate, are described as a function of the contrast of viscosity between the inner and the outer fluids, and as a function of the distance from the wall. Results are compared to models developed for ellipsoids of fixed shape. Finally, we showed that RBC oscillate while tank-treading and by increasing the shear rate, they pass from tank treading to tumbling, which discloses the existence of a characteristic time that is related to the visco-elasticity of their cytoskeleton.

  14. A Comparative experimental study of media access protocols for wireless radio networks

    SciTech Connect

    Barrett, C. L.; Drozda, M.; Marathe, M. V.

    2001-05-24

    We conduct a comparative experimental analysis of three well known media access protocols: 802.11, CSMA, and MACA for wireless radio networks. Both fixed and ad-hoc networks are considered. The experimental analysis was carried out using GloMoSim: a tool for simulating wireless networks. The main focus of experiments was to study how (i) the size of the network, (ii) number of open connections, (iii) the spatial location of individual connections, (iv) speed with which individual nodes move and (v) protocols higher up in the protocol stack (e,g. routing layer) affect the performance of the media access sublayer protocols. The performance of the protocols was measured w.r.t. three important parameters: (1) number of received packets, (2) average latency of each packet, and (3) throughput. The following general qualitative conclusions were obtained; some of the conclusions reinforce the earlier claims by other researchers. (1) Although 802.11 performs better than the other two protocols with respect to fairness of transmission, packets dropped, and latency, its performance is found to (i) show a lot of variance with changing input parameters and (ii) the overall performance still leaves a lot of room for improvement. (2) CSMA does not perform too well under the fairness criteria, however, was the best in terms of the latency criteria. (3) MACA also shows fairness problems and has poor performance at high packet injection rates. (4) Protocols in the higher level of the protocol stack affect the MAC layer performance. The main general implications of our work is two folds: (1) No single protocol dominated the other protocols across various measures of efficiency. This motivates the design of a new class of parameterized protocols that adapt to changes in the network connectivity and loads. We refer to these class of protocols as parameterized dynamically adaptive efficient protocols and as a first step suggest key design requirements for such a class of protocols. (2

  15. Comparative Experimental Infection Study in Dogs with Ehrlichia canis, E. chaffeensis, Anaplasma platys and A. phagocytophilum

    PubMed Central

    Nair, Arathy D. S.; Cheng, Chuanmin; Ganta, Chanran K.; Sanderson, Michael W; Alleman, Arthur R.; Munderloh, Ulrike G.; Ganta, Roman R.

    2016-01-01

    Dogs acquire infections with the Anaplasmataceae family pathogens, E. canis, E. chaffeensis, E. ewingii, A. platys and A. phagocytophilum mostly during summer months when ticks are actively feeding on animals. These pathogens are also identified as causing diseases in people. Despite the long history of tick-borne diseases in dogs, much remains to be defined pertaining to the clinical and pathological outcomes of infections with these pathogens. In the current study, we performed experimental infections in dogs with E. canis, E. chaffeensis, A. platys and A. phagocytophilum. Animals were monitored for 42 days to evaluate infection-specific clinical, hematological and pathological differences. All four pathogens caused systemic persistent infections detectible throughout the 6 weeks of infection assessment. Fever was frequently detected in animals infected with E. canis, E. chaffeensis, and A. platys, but not in dogs infected with A. phagocytophilum. Hematological differences were evident in all four infected groups, although significant overlap existed between the groups. A marked reduction in packed cell volume that correlated with reduced erythrocytes and hemoglobin was observed only in E. canis infected animals. A decline in platelet numbers was common with E. canis, A. platys and A. phagocytophilum infections. Histopathological lesions in lung, liver and spleen were observed in all four groups of infected dogs; infection with E. canis had the highest pathological scores, followed by E. chaffeensis, then A. platys and A. phagocytophilum. All four pathogens induced IgG responses starting on day 7 post infection, which was predominantly comprised of IgG2 subclass antibodies. This is the first detailed investigation comparing the infection progression and host responses in dogs after inoculation with four pathogens belonging to the Anaplasmataceae family. The study revealed a significant overlap in clinical, hematological and pathological changes resulting from the

  16. Comparative Experimental Infection Study in Dogs with Ehrlichia canis, E. chaffeensis, Anaplasma platys and A. phagocytophilum.

    PubMed

    Nair, Arathy D S; Cheng, Chuanmin; Ganta, Chanran K; Sanderson, Michael W; Alleman, Arthur R; Munderloh, Ulrike G; Ganta, Roman R

    2016-01-01

    Dogs acquire infections with the Anaplasmataceae family pathogens, E. canis, E. chaffeensis, E. ewingii, A. platys and A. phagocytophilum mostly during summer months when ticks are actively feeding on animals. These pathogens are also identified as causing diseases in people. Despite the long history of tick-borne diseases in dogs, much remains to be defined pertaining to the clinical and pathological outcomes of infections with these pathogens. In the current study, we performed experimental infections in dogs with E. canis, E. chaffeensis, A. platys and A. phagocytophilum. Animals were monitored for 42 days to evaluate infection-specific clinical, hematological and pathological differences. All four pathogens caused systemic persistent infections detectible throughout the 6 weeks of infection assessment. Fever was frequently detected in animals infected with E. canis, E. chaffeensis, and A. platys, but not in dogs infected with A. phagocytophilum. Hematological differences were evident in all four infected groups, although significant overlap existed between the groups. A marked reduction in packed cell volume that correlated with reduced erythrocytes and hemoglobin was observed only in E. canis infected animals. A decline in platelet numbers was common with E. canis, A. platys and A. phagocytophilum infections. Histopathological lesions in lung, liver and spleen were observed in all four groups of infected dogs; infection with E. canis had the highest pathological scores, followed by E. chaffeensis, then A. platys and A. phagocytophilum. All four pathogens induced IgG responses starting on day 7 post infection, which was predominantly comprised of IgG2 subclass antibodies. This is the first detailed investigation comparing the infection progression and host responses in dogs after inoculation with four pathogens belonging to the Anaplasmataceae family. The study revealed a significant overlap in clinical, hematological and pathological changes resulting from the

  17. A comparative study of experimental mouse models of central nervous system demyelination.

    PubMed

    Dumitrascu, O M; Mott, K R; Ghiasi, H

    2014-06-01

    Several mouse models of multiple sclerosis (MS) are now available. We have established a mouse model, in which ocular infection with a recombinant HSV-1 that expresses murine interleukin (IL)-2 constitutively (HSV-IL-2) causes central nervous system demyelination in different strains of mice. This model differs from most other models, in which it represents a mixture of viral and immune triggers. In the present study, we directly compared MOG35-55, MBP35-47 and PLP190-209 models of experimental autoimmune encephalitis with our HSV-IL-2-induced MS model. Mice with HSV-IL-2- and myelin oligodendrocyte glycoprotein (MOG)-induced demyelinating diseases demonstrated a similar pattern and distribution of demyelination in their brain, spinal cord (SC) and optic nerves (ONs). In contrast, no demyelination was detected in the ONs of myelin basic protein (MBP)- and proteolipid protein (PLP)-injected mice. Interferon-β (IFN-β) injections significantly reduced demyelination in brains of all groups, in the SCs of the MOG and MBP groups, and completely blocked it in the SCs of the PLP and HSV-IL-2 groups as well as in ONs of MOG and HSV-IL-2 groups. In contrast to IFN-β treatment, IL-12p70 protected the HSV-IL-2 group from demyelination, whereas IL-4 was not effective at all in preventing demyelination. MOG-injected mice showed clinical signs of paralysis and disease-related mortality, whereas mice in the other treatment groups did not. Collectively, the results indicate that the HSV-IL-2 model and the MOG model complement each other and, together, provide unique insights into the heterogeneity of human MS. PMID:24718267

  18. Spectroscopic and vibrational analysis of the methoxypsoralen system: A comparative experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Yuan, H.; Vo-Dinh, T.

    2013-03-01

    Raman spectra measurements and density functional theory (DFT) calculations were performed to investigate three psoralens: 5-amino-8-methoxypsoralen (5-A-8-MOP), 5-methoxypsoralen (5-MOP) and 8-methoxypsoralen (8-MOP) with the aim of differentiating these similar bioactive molecules. The Raman spectra were recorded in the region 300-3500 cm-1. All three psoralens were found to have similar Raman spectrum in the region 1500-1650 cm-1. 5-A-8-MOP can be easily differentiated from 5-MOP or 8-MOP based on the Raman spectrum. The Raman spectrum differences at 651 and 795 cm-1 can be used to identify 5-MOP from 8-MOP. The theoretically computed vibrational frequencies and relative peak intensities were compared with experimental data. DFT calculations using the B3LYP method and 6-311++G(d,p) basis set were found to yield results that are very comparable to experimental Raman spectra. Detailed vibrational assignments were performed with DFT calculations and the potential energy distribution (PED) obtained from the Vibrational Energy Distribution Analysis (VEDA) program.

  19. A comparative experimental study on structural and interface damping approaches for vibration suppression purposes

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Sanchez, Alberto; Zogg, Markus; Ermanni, Paolo

    2010-04-01

    Dynamic loadings in automotive structures may lead to reduction of driving comfort and even to failure of the components. Damping treatments are applied in order to attenuate the vibrations and improve the long term fatigue behavior of the structures. This experimental study is targeting applications in floor panels that are mounted to the loadcarrying primary structure of the vehicle. The objective is to reach outstanding damping performance considering the stringent weight and cost requirement in the automotive industry. An experimental setup has been developed and validated for the determination of the damping properties of structural specimens also considering interface damping effects. This contribution is structured in three main parts: test rig design, experimental results and discussion. Reliable and easy-to-use devices for the characterization of the damping properties of specimens between 200×40 mm2 and 400×400 mm2 are not available "on the shelf". In this context, we present a flexible experimental set-up which has been realized to (1) support the development of novel damping solutions for multi-functional composite structures; (2) characterize the loss-factor of the different damping concepts, including boundary effects. A variety of novel passive and active damping treatments have been investigated including viscoelastic, coulomb, magnetorheological (MR), particle, magnetic and eddy current damping. The particle, interface as well as active damping systems show promising performance in comparison to the classical viscoelastic treatments.

  20. Spectroscopic and structural investigations of iron(III) isothiocyanates. A comparative theoretical and experimental study.

    PubMed

    Elijošiutė, Erika; Eicher-Lorka, Olegas; Griškonis, Egidijus; Kuodis, Zenonas; Jankūnaitė, Dalia; Denafas, Gintaras

    2014-08-14

    A combined experimental and theoretical study on the molecular structure and vibrational spectra of [Fe(NCS)](2+) complex in the aqueous solution at the pH∼2 ± 0.1 have been performed. Experimental Raman spectra of the iron(III) isothiocyanate with higher coordination number in the acidic aqueous solution have been analyzed. Molecular modeling of the iron(III) monoisothiocyanate complex was accomplished by the density functional theory (DFT) method using B3LYP and PBE1PBE functionals. Theoretical vibrational spectra of the iron(III) monoisothiocyanate were interpreted by means of the potential energy distributions (PEDs). The influence of different solvation models and position of SO4(2)(-) ligand vs. NCS(-) ligand upon its geometry and vibrational frequencies have been evaluated. The effect of H2O/D2O isotopic substitution on the experimental and calculated Raman spectra of iron(III) isothiocyanates has been examined. Procedures of Raman spectra subtraction have been applied for the extractions of weak and/or obscured Raman signals. As a result, the presence of bound SO4(2)(-) ion and water molecules in the first coordination sphere in the acidic aqueous iron(III) isothiocyanate solution was confirmed. The vibrational assignments for the investigated iron(III) isothiocyanates were proposed here for the first time. PMID:24721282

  1. Theoretical and experimental comparative study of a derivative from 2-pyridinecarboxaldehyde which exhibits configurational dynamics

    NASA Astrophysics Data System (ADS)

    Gordillo, Mónica A.; Soto-Monsalve, Mónica; Gutiérrez, Gustavo; D'vries, Richard F.; Chaur, Manuel N.

    2016-09-01

    The (E)-4-nitro-N‧-(pyridine-2-ylmethylene)benzohydrazide, a derivative from 2-pyridinecarboxaldehyde, displays E/Z isomerization induced by ultraviolet radiation in which the process of photoisomerization was evidenced and followed by 1D 1H NMR. The structure of the compound was determined by FT-IR and NMR techniques and confirmed by single-crystal X-ray diffraction. The results in terms of bond angle and length, chemical shift (13C and 1H) and vibrational frequencies obtained experimentally were compared to computed values at two levels of theory (Restricted Hartree-Fock and Density Functional Theory) using different basis set. The understanding of spectroscopy and dynamic properties of these type of compounds is of importance in view of their potential use in molecular machines and electronic devices.

  2. A comparative study of behaviors of ventilated supercavities between experimental models with different mounting configurations

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Jae; Kawakami, Ellison; Karn, Ashish; Arndt, Roger E. A.

    2016-08-01

    Small-scale water tunnel experiments of the phenomenon of supercavitation can be carried out broadly using two different kinds of experimental models–in the first model (forward facing model, or FFM), the incoming flow first interacts with the cavitator at front, which is connected to the strut through a ventilation pipe. The second model could have the strut and the ventilation pipe preceding the cavitator (backward facing model, or BFM). This is the continuation of a water tunnel study of the effects of unsteady flows on axisymmetric supercavities. In this study, the unwanted effect of test model configuration on supercavity shape in periodic flows was explored through a comparison of FFM and BFM models. In our experiments, it was found that periodic gust flows have only a minimal effect on the maximum diameter and the cavity length can be shortened above a certain vertical velocity of periodic flows. These findings appear to be robust regardless of the model configuration.

  3. Height of burst explosions: a comparative study of numerical and experimental results

    NASA Astrophysics Data System (ADS)

    Omang, M.; Christensen, S. O.; Børve, S.; Trulsen, J.

    2009-06-01

    In the current work, we use the Constant Volume model and the numerical method, Regularized Smoothed Particle Hydrodynamics (RSPH) to study propagation and reflection of blast waves from detonations of the high explosives C-4 and TNT. The results from simulations of free-field TNT explosions are compared to previously published data, and good agreement is found. Measurements from height of burst tests performed by the Norwegian Defence Estates Agency are used to compare against numerical simulations. The results for shock time of arrival and the pressure levels are well represented by the numerical results. The results are also found to be in good agreement with results from a commercially available code. The effect of allowing different ratios of specific heat capacities in the explosive products are studied. We also evaluate the effect of changing the charge shape and height of burst on the triple point trajectory.

  4. Neointimal Hyperplasia in Low-Profile Nitinol Stents, Palmaz Stents, and Wallstents: A Comparative Experimental Study

    SciTech Connect

    Schuermann, Karl; Vorwerk, Dierk; Kulisch, Arthur; Stroehmer-Kulisch, Eva; Biesterfeld, Stefan; Stopinski, Tadeusz; Guenther, Rolf W.

    1996-04-15

    Purpose: To compare neointima formation following insertion of low-profile Nitinol stents, Palmaz stents, and Wallstents. Methods: Nitinol stents, Palmaz stents, and Wallstents similar in size were transfemorally inserted into the iliac arteries of 12 sheep. Four stents per sheep were deployed; the position of the stents was varied so that each type of stent was placed in each position (right or left, proximal or distal) with equal frequency. Stent patency was followed by angiography. Six sheep were euthanized after 1 month, and the remaining six after 6 months. Iliac arteries were removed en bloc and prepared for histological examination. Neointimal and medial thickness were measured by light microscopy, and measurements were analyzed statistically. Results: Mean neointimal thickness both over (NO) and between (NB) the stent struts was greater in Wallstents (NO = 0.341 mm, NB = 0.368 mm) than in the Nitinol (NO = 0.260 mm, NB = 0.220 mm) and Palmaz stents (NO = 0.199 mm, NB = 0.204 mm), but differences were not significant (p> 0.05). Medial atrophy in the area between the stent struts was greater in Wallstents compared with Nitinol and Palmaz stents (p < 0.007 and p < 0.02, respectively); in the area under the stent struts there was a significant difference only between Palmaz stents and Wallstents (p < 0.02). Conclusion: Under defined experimental conditions, none of the three types of stent appears to be preferable to the others regarding neointima formation in the short- to mid-term follow-up period.

  5. A comparative study of experimental and simulated ultrasonic pulse-echo signals from multilayered structures

    NASA Technical Reports Server (NTRS)

    Abedin, M. N.; Prabhu, D. R.; Winfree, W. P.; Johnston, P. H.

    1992-01-01

    The effect on the system acoustic response of variations in the adhesive thickness, coupling thickness, and paint thickness is considered. Both simulations and experimental measurements are used to characterize and classify A-scans from test regions, and to study the effects of various parameters such as paint thickness and epoxy thickness on the variations in the reflected signals. A 1D model of sound propagation in multilayered structures is used to verify the validity of the measured signals, and is also used to computationally generate signals for a class of test locations with gradually varying parameters. This approach exploits the ability of numerical simulations to provide a good understanding of the ultrasonic pulses reflected at disbonds.

  6. COMPARATIVE STUDY ON IMMUNOBLOT VERSUS PCR IN DIAGNOSIS OF SCHISTOSOMIASIS MANSONI IN EXPERIMENTAL INFECTED MICE.

    PubMed

    Ismail, Mousa A M; Mousa, Wahed Mohammed Ali; Abu-Sarea, Enas Yahia; Basyouni, Maha M A; Mohammed, Samah Sayed

    2016-04-01

    This study compared PCR and Western blot techniques in diagnosis of schistosomiasis mansoni. Forty Swiss albino mice were used, thirty two mice were infected with cercariae of S. mansoni and eight mice were kept uninfected which were used as a control. Blood was obtained from four infected mice weekly beginning from the 1st week to the 8th week post infection. The study found that PCR was positive from the first week post infection, while Western blot technique was positive from the second week post infection. Thus, PCR diagnosed schistosomiasis mansoni earlier than Western blot technique, but both were able to diagnose. PMID:27363045

  7. Comparative Evaluation of Ciprofloxacin Levels in GCF and Plasma of Chronic Periodontitis Patients: Quasi Experimental Study

    PubMed Central

    Denthumdas, Sunil Kumar; Wadgave, Umesh; Pharne, Pooja Mohan; Patil, Sandeep Jambukumar; Kondreddi, Sirisha; Deshpande, Pavan; Koppikar, Rajesh Suresh

    2016-01-01

    Introduction For any antimicrobial approach to be successful in periodontal therapy, it is important that the antimicrobial agent targets the sub-gingival biofilm by attaining sufficient concentration at the sub-gingival site. Aim The purpose of the present study was to determine and compare the concentrations of ciprofloxacin present in Gingival Crevicular Fluid (GCF) and plasma after its systemic administration. Materials and Methods A total of 20 subjects, in the age group of 30-60 years satisfying the inclusion and exclusion criteria, were chosen from the outpatient Department of Periodontology, Government Dental College and Hospital, Hyderabad and consent was obtained. Subjects were put on oral ciprofloxacin therapy (Baycip, Bayer Corporation) of 500mg twice daily doses for five days to establish steady state tissue levels of the agent. GCF and serum samples were collected at the 72nd hour after the first dose of ciprofloxacin and were compared using unpaired t test. Results The mean gingival index value of the subjects was 1.8 ± 0.59 and the mean probing depth of the subjects taken in the study was 5.724 ± 0.47mm. The results of this study showed that ciprofloxacin concentrations were significantly higher (p<0.001) in GCF than in plasma. Conclusion Results from the present study and those from the earlier studies clearly indicate the ciprofloxacin’s ability to reach and concentrate in infected periodontal sites via GCF. This property of ciprofloxacin may be useful for eradication of periodontal pathogens, thus improving the outcome of periodontal therapy. PMID:27504410

  8. Comparing the effects of nebivolol and dexpanthenol on wound healing: an experimental study.

    PubMed

    Ulger, Burak V; Kapan, Murat; Uslukaya, Omer; Bozdag, Zubeyir; Turkoglu, Ahmet; Alabalık, Ulas; Onder, Akın

    2016-06-01

    Wound healing is a dynamic, interactive process that is initiated in response to injury. A number of investigations and clinical studies have been performed to determine new approaches for the improvement of wound healing. The aim of this study was to compare the effects of dexpanthenol, a molecule that is widely used for improving wound healing, and nebivolol, a molecule that increases nitric oxide release, on wound healing. A total of 30 rats were divided into three equal groups (n = 10). A linear 2 cm incision was made in the rats' skin. No treatment was administered in the first (control) group. Dexpanthenol cream was administered to the rats in the second group and 5% nebivolol cream was administered to the rats in the third group. The wound areas of all of the rats were measured on certain days. On the 21(st) day, all wounds were excised and histologically evaluated. The wound healing rates of the dexpanthenol and nebivolol groups were higher than those of the control group (P < 0·05). However, the wound healing rates of the dexpanthenol and nebivolol groups were not significantly different. Nebivolol and dexpanthenol have comparable effects on wound healing. PMID:25040679

  9. Comparative Experimental and Computational Study of Monoalkyl Chain Phosphatidylcholine-Containing Thermoresponsive Liposomes.

    PubMed

    Eleftheriou, Kleopatra; Sideratou, Zili; Thanassoulas, Angelos; Papakyriakou, Athanasios; Tsiourvas, Dimitris

    2016-06-23

    Liposomes containing lysophospholipids are intensively studied as drug delivery systems that are stable at normal body temperature but exhibit fast release of their drug load at slightly elevated temperatures. In this study, the stability and release properties of dipalmitoylglycerophosphocholine (DPPC)-based liposomes incorporating the commonly used lysophosphatidylocholine (lyso-PC), and a series of monoalkyl chain ether-linked phosphatidylcholine, i.e., the biologically relevant monoalkyl chain platelet activating factor (PAF) and its derivatives lyso-PAF and methyl-PAF, were investigated. To this end a series of PEGylated small unilamellar liposomes with DPPC:monoalkyl lipid compositions of 5% and 10% molar ratio were prepared and compared with regard to stability (37 °C) and release properties at elevated temperatures (38-43 °C). All systems were characterized with respect to size distribution, ζ-potential, and phase transition characteristics. The presence of ether-lipids endows liposomes with superior (∼10% increase) release properties at 5% incorporation compared to lyso-PC, while at 10% molar ratio the formulations do not differ significantly, the release being close to 90%. The findings are supported by atomistic molecular dynamics simulations that suggest a correlation between the enhanced permeability and increased penetration of water molecules within the bilayers with density fluctuations resulting from the increased area-per-lipid and the disorder of the lysolipids alkyl chains. PMID:27280363

  10. A comparative experimental study of gross alpha methods in natural waters.

    PubMed

    Montaña, M; Fons, J; Corbacho, J A; Camacho, A; Zapata-García, D; Guillén, J; Serrano, I; Tent, J; Baeza, A; Llauradó, M; Vallés, I

    2013-04-01

    The aim of the present work was to compare the results obtained with gross alpha methods such as evaporation, co-precipitation and total evaporation by liquid scintillation counting and to check whether these results are representative of the real total alpha activity concentration on the sample. The study was carried out on eight natural waters with very different radioactive characteristics. For all the samples uranium ((238)U, (235)U, and (234)U), radium ((226)Ra and (224)Ra), (210)Po, and (232)Th isotopes were also assayed by using radiochemical separation and alpha spectrometry in order to determine the sum of the activities of these alpha emitters. Precision (expressed as relative standard deviation) was below 28% for evaporation and below 18% for co-precipitation. In the case of total by liquid scintillation counting it was below 10% for samples with Total Alpha activity above 0.1 Bq/L (this value is about three times the MDA). Furthermore, for most of the studied waters, the Total Alpha activity and the gross alpha activity determined by the three methods were comparable. The obtained bias by the evaporation, co-precipitation, and total evaporation by liquid scintillation counting methods was lower than 40%, 25% and 20%, respectively. The ANOVA test was applied to find out if there was significant variability among the methods. For the samples with the most common radiochemical characteristics there were no significant differences among the three studied methods. However differences were detected for samples with a high saline content or with a very low activity level. PMID:23220539

  11. Quercetin prevents experimental glucocorticoid-induced osteoporosis: a comparative study with alendronate.

    PubMed

    Derakhshanian, Hoda; Djalali, Mahmoud; Djazayery, Abolghassem; Nourijelyani, Keramat; Ghadbeigi, Sajad; Pishva, Hamideh; Saedisomeolia, Ahmad; Bahremand, Arash; Dehpour, Ahmad Reza

    2013-05-01

    Glucocorticoid-induced osteoporosis (GIO) is the most common type of secondary osteoporosis. The aim of this study was to compare the efficacy of quercetin, a plant-derived flavonoid, with alendronate in the prevention of GIO. Fifty-six Sprague-Dawley rats were randomly distributed among 7 groups (8 rats per group) and treated for 6 weeks with one of the following: (i) normal saline; (ii) 40 mg methylprednisolone sodium succinate (MP)/kg body mass; (iii) MP + 40 μg alendronate/kg; (iv) MP + 50 mg quercetin/kg; (v) MP + 40 μg alendronate/kg + 50 mg quercetin/kg; (vi) MP + 150 mg quercetin/kg; and (vii) MP + 40 μg alendronate/kg + 150 mg quercetin/kg. MP and alendronate were injected subcutaneously and quercetin was administered by oral gavage 3 days a week. At the end of the study, femur breaking strength was significantly decreased as a consequence of MP injection. This decrease was completely compensated for in groups receiving 50 mg quercetin/kg plus alendronate, and 150 mg quercetin/kg with or without alendronate. Quercetin noticeably elevated osteocalcin as a bone formation marker, while alendronate did not show such an effect. In addition, administration of 150 mg quercetin/kg increased femoral trabecular and cortical thickness by 36% and 22%, respectively, compared with the MP-treated group. These data suggest that 150 mg quercetin/kg, alone or in combination with alendronate, can completely prevent GIO through its bone formation stimulatory effect. PMID:23656499

  12. Comparative Experimental and Modeling Study of Fluid Velocities in Heterogeneous Rocks

    NASA Astrophysics Data System (ADS)

    Hingerl, F.; Romanenko, K.; Pini, R.; Balcom, B.; Benson, S. M.

    2013-12-01

    Understanding the spatial distribution of fluid velocities and effective porosities in rocks is crucial for predicting kinetic reaction rates and fluid-rock interactions in a plethora of geo-engineering applications, ranging from geothermal systems, Enhanced Oil Recovery to Carbon Capture and Storage. Magnetic Resonance Imaging can be used to measure spatially resolved porosities and fluid velocities in porous media. Large internal field gradients and short spin relaxation times, however, constrain the usability of the conventional MRI technique in natural rock samples. The combination of three-dimensional Single Point Ramped Imaging with T1 Enhancement (SPRITE) and the 13-interval Alternating-Pulsed-Gradient Stimulated-Echo (APGSTE) scheme - a method developed at the UNB MRI Center - is able to compensate for those challenges and quantitative 3 dimensional maps of porosities and fluid velocities can be obtained. In this study we measured velocities and porosities using MRI in a sandstone rock sample showing meso-scale heterogeneities. Then we generated permeabilities using three independent approaches, employed them to model single-phase fluid flow in the measured rock sample and compared the generated velocity maps with the respective MRI measurements. For the first modeling approach, we applied the Kozeny-Carman relationship to create a permeability map based on porosities measured using MRI. For the second approach we used permeabilities derived from CO2-H2O multi-phase experiments performed in the same rock sample assuming the validity of the J-Leverett function. The permeabilities in the third approach were generated by applying a new inverse iterative-updating technique. The resulting three permeability maps were then used as input for a CFD simulation - using the Stanford CFD code AD-GPRS - to create a respective velocity map, which in turn was then compared to the measured velocity map. The results of the different independent methods for generating

  13. Four alginate dressings in the treatment of partial thickness wounds: a comparative experimental study.

    PubMed

    Agren, M S

    1996-03-01

    Alginate-based absorption materials for wound treatment are meeting with increasing clinical acceptance. The purpose of this study was to compare four different calcium alginate dressings (Algosteril, Comfeel Alginate, Kaltostat and Sorbsan) with respect to wound fluid retaining ability, adherence, dressing residues, epithelialisation and inflammatory cell infiltration using a standardised partial-thickness wound model in domestic pigs. Wound fluid spread laterally onto surrounding normal skin by about 40% more with Sorbsan than with the other alginate dressings after 24 h of treatment (P = 0.026). The corresponding figure after 66 h of treatment was 20% (P = 0.030). Algosteril (mean 1.7 [sem 0.3]) adhered significantly (P = 0.014) more to the wounds than Comfeel Alginate (mean 0.2 [0.2]). Kaltostat (mean 1.8 [0.3]) left significantly (P = 0.038) more dressing residues on the wound surface at dressing removal than the Comfeel Alginate dressing (mean 0.8 [0.2]). In the effect on epithelialisation or dermal inflammation there was no statistically significant difference at significance level 5% among the four alginate dressings, as assessed by light microscopy. In summary, the four alginate dressings showed significant differences in important handling characteristics and did not differ significantly in their effect on epithelialisation. PMID:8733355

  14. A comparative study of experimental mouse models of central nervous system demyelination

    PubMed Central

    Dumitrascu, Oana M.; Mott, Kevin R.; Ghiasi, Homayon

    2014-01-01

    Several mouse models of multiple sclerosis (MS) are now available. We have established a mouse model, in which ocular infection with a recombinant HSV-1 that expresses murine IL-2 constitutively (HSV-IL-2) causes CNS demyelination in different strains of mice. This model differs from most other models in that it represents a mixture of viral and immune triggers. In the present study, we directly compared MOG35–55, MBP35–47, and PLP190–209 models of EAE with our HSV-IL-2-induced MS model. Mice with HSV-IL-2-induced and MOG-induced demyelinating diseases demonstrated a similar pattern and distribution of demyelination in their brain, spinal cord, and optic nerves. In contrast, no demyelination was detected in the optic nerves of MBP- and PLP-injected mice. IFN-β injections significantly reduced demyelination in brains of all groups, in the spinal cords of the MOG and MBP groups, and completely blocked it in the spinal cords of the PLP and HSV-IL-2 groups as well as in optic nerves of MOG and HSV-IL-2 groups. In contrast to IFN-β treatment, IL-12p70 protected the HSV-IL-2 group from demyelination, while IL-4 was not effective at all in preventing demyelination. MOG-injected mice showed clinical signs of paralysis and disease-related mortality whereas mice in the other treatment groups did not. Collectively, the results indicate that the HSV-IL-2 model and the MOG model complement each other and, together, provide unique insights into the heterogeneity of human MS. PMID:24718267

  15. A comparative study of soft sensor design for lipid estimation of microalgal photobioreactor system with experimental validation.

    PubMed

    Yoo, Sung Jin; Jung, Dong Hwi; Kim, Jung Hun; Lee, Jong Min

    2015-03-01

    This study examines the applicability of various nonlinear estimators for online estimation of the lipid concentration in microalgae cultivation system. Lipid is a useful bio-product that has many applications including biofuels and bioactives. However, the improvement of lipid productivity using real-time monitoring and control with experimental validation is limited because measurement of lipid in microalgae is a difficult and time-consuming task. In this study, estimation of lipid concentration from other measurable sources such as biomass or glucose sensor was studied. Extended Kalman filter (EKF), unscented Kalman filter (UKF), and particle filter (PF) were compared in various cases for their applicability to photobioreactor systems. Furthermore, simulation studies to identify appropriate types of sensors for estimating lipid were also performed. Based on the case studies, the most effective case was validated with experimental data and found that UKF and PF with time-varying system noise covariance is effective for microalgal photobioreactor system. PMID:25545097

  16. Synthesis, crystal structures and spectroscopic properties of triazine-based hydrazone derivatives; a comparative experimental-theoretical study.

    PubMed

    Arshad, Muhammad Nadeem; Bibi, Aisha; Mahmood, Tariq; Asiri, Abdullah M; Ayub, Khurshid

    2015-01-01

    We report here a comparative theoretical and experimental study of four triazine-based hydrazone derivatives. The hydrazones are synthesized by a three step process from commercially available benzil and thiosemicarbazide. The structures of all compounds were determined by using the UV-Vis., FT-IR, NMR (1H and 13C) spectroscopic techniques and finally confirmed unequivocally by single crystal X-ray diffraction analysis. Experimental geometric parameters and spectroscopic properties of the triazine based hydrazones are compared with those obtained from density functional theory (DFT) studies. The model developed here comprises of geometry optimization at B3LYP/6-31G (d, p) level of DFT. Optimized geometric parameters of all four compounds showed excellent correlations with the results obtained from X-ray diffraction studies. The vibrational spectra show nice correlations with the experimental IR spectra. Moreover, the simulated absorption spectra also agree well with experimental results (within 10-20 nm). The molecular electrostatic potential (MEP) mapped over the entire stabilized geometries of the compounds indicated their chemical reactivates. Furthermore, frontier molecular orbital (electronic properties) and first hyperpolarizability (nonlinear optical response) were also computed at the B3LYP/6-31G (d, p) level of theory. PMID:25854752

  17. Note: Comparative experimental studies on the performance of 2-2 piezocomposite for medical ultrasound transducers.

    PubMed

    Marinozzi, F; Bini, F; Biagioni, A; Grandoni, A; Spicci, L

    2013-09-01

    The paper reports the experimental investigation of the behavior of 2-2 Lead Zirconate Titanate (PZT)-polymer composite transducers array for clinical ultrasound equipments. Several 2-2 plate composites having the same dicing pitch of 0.11 mm and different volume fractions were manufactured and investigated. Measurements were performed through different techniques such as electrical impedance, pulse-echo, and Laser Doppler Vibrometer. With the last one, maps of the surface displacement were presented relative to thickness mode and first lateral mode resonance frequencies. The transducers with volume fractions of the 40% resulted markedly inefficient, whereas the largest bandwidth and best band shape were achieved by the 50%. PMID:24089885

  18. An experimental comparative study of 20 Italian opera houses: Measurement techniques

    NASA Astrophysics Data System (ADS)

    Farina, Angelo; Armelloni, Enrico; Martignon, Paolo

    2001-05-01

    For ``acoustical photography'' we mean a set of measured impulse responses, which enable us to ``listen'' at the measured room by means of advanced auralization methods. Once these data sets have been measured, they can be employed in two different ways: objective analysis and listening test. In fact, it is possible to compute dozens of acoustical objective parameters, describing the temporal texture, the spatial effect and the frequency-domain coloring of each opera house. On the other hand, by means of the auralization technique, it becomes easy to conduct listening experiments with human subjects. This paper focuses principally on the development and specification of the measurement technique, which is the topic assigned to the research unit of Parma, to which the authors belong. It describes the hardware equipment, the software, the electro-acoustic transducers (microphones and loudspeakers), the measurement positions, the system for automatic displacement of the microphones and the conditions of the room during the measurements. Experimental results are reported about a couple of opera houses which were employed for testing the measurement procedure and showing the benefits of the new method against the previously employed ones.

  19. Experimental shock metamorphism of mono- and polycrystalline olivine - A comparative study

    NASA Technical Reports Server (NTRS)

    Bauer, J. F.

    1979-01-01

    The paper reports on a series of controlled shock recovery experiments which have been performed on over 40 samples including monocrystalline, polycrystalline, dunite, and porous particulate olivine-bearing targets. Results of the mineralogical and petrological analyses of these samples are used to establish a general and comparative diagnosis of shock effects generated in various olivine-bearing materials. Finally, some experiments are conducted under different ambient pO2 conditions so that information on the distribution of observed impact features is derived as a function not only of peak pressure and texture of the target sample, but also of specific environmental conditions.

  20. Comparing Different Approaches to Visualizing Light Waves: An Experimental Study on Teaching Wave Optics

    ERIC Educational Resources Information Center

    Mešic, Vanes; Hajder, Erna; Neumann, Knut; Erceg, Nataša

    2016-01-01

    Research has shown that students have tremendous difficulties developing a qualitative understanding of wave optics, at all educational levels. In this study, we investigate how three different approaches to visualizing light waves affect students' understanding of wave optics. In the first, the conventional, approach light waves are represented…

  1. Pleurodesis with Thulium Cyber Laser versus talc poudrage: a comparative experimental study.

    PubMed

    Droghetti, Andrea; Vannucci, Jacopo; Bufalari, Antonello; Bellezza, Guido; De Monte, Valentina; Marulli, Giuseppe; Bottoli, Maria Caterina; Giovanardi, Michele; Daddi, Niccolò; De Angelis, Verena; Moriconi, Franco; Puma, Francesco

    2016-09-01

    Sclerosing fluids to achieve pleurodesis could be hardly replaced for bed-side procedures, but other devices may be successfully applied during thoracoscopy. Thulium Cyber Laser was experimented for this purpose and compared to talc poudrage. Twenty pigs underwent operative videothoracoscopy (VATS). Ten models were subjected to double-port VATS and parietal pleura photoevaporation using Thulium Cyber Laser™ (TCL) 150 W 2010 nm on the posterior third of three ribs; the pleural surface was homogeneously treated inside the target perimeter. The remaining ten pigs underwent uniportal thoracoscopy; talc poudrage was performed using the current clinical practice dosage (1 g/18 kg) with accurate talc powder spread over the whole pleural surface. All models were followed up for 60 days. Pleurodesis firmness was graded on a three-tier scale (none-moderate-firm) and site-matching topographical expectancy was evaluated. TCL produced pleurodesis in all models: 7/10 were firm and 3/10 moderate. Talc poudrage pleurodesis was firm in 4/10 and moderate in 6/10. Pleural adhesions were found exclusively in the treated area after laser treatment, while talc created a wide spectrum of effects, most commonly anarchic jagged adhesions obliterating less than 50 % of the pleural cavity (7/10), mostly declivous. The pathologist found more aggressive inflammation (sometimes severe) in the talc group. Expected localized pleurodesis was always registered in laser group (10/10), while talc poudrage was found poorly effective if consistent pleurodesis is expected in an apico-dorsal position (2/10). Laser pleurodesis appears more homogeneous, qualitatively not inferior, and topographically more predictable than talc pleurodesis. Parietal photoevaporation seems effective and the localized pleurodesis is reproducible. PMID:27372097

  2. Comparative study of the biological properties of Trypanosoma cruzi I genotypes in a murine experimental model.

    PubMed

    Cruz, Lissa; Vivas, Angie; Montilla, Marleny; Hernández, Carolina; Flórez, Carolina; Parra, Edgar; Ramírez, Juan David

    2015-01-01

    Chagas disease is an endemic zoonosis in Latin America and caused by the parasite Trypanosoma cruzi. This kinetoplastid displays remarkable genetic variability, allowing its classification into six Discrete Typing Units (DTUs) from TcI to TcVI. T. cruzi I presents the broadest geographical distribution in the continent and has been associated to severe forms of cardiomyopathies. Recently, a particular genotype associated to human infections has been reported and named as TcIDOM (previously named TcIa-b). This genotype shows to be clonal and adapted to the domestic cycle but so far no studies have determined the biological properties of domestic (TcIDOM) and sylvatic TcI strains (previously named TcIc-e). Hence, the aim of this study was to untangle the biological features of these genotypes in murine models. We infected ICR-CD1 mice with five TcI strains (two domestic, two sylvatic and one natural mixture) and determined the course of infection during 91 days (acute and chronic phase of the disease) in terms of parasitemia, tissue tropism, immune response (IgG titers) and tissue invasion by means of histopathology studies. Statistically significant differences were observed in terms of parasitemia curves and prepatent period between domestic (TcIDOM) and sylvatic strains. There were no differences in terms of IgG antibodies response across the mice infected with the five strains. Regarding the histopathology, our results indicate that domestic strains present higher parasitemias and low levels of histopathological damage. In contrast, sylvatic strains showed lower parasitemias and high levels of histopathological damage. These results highlight the sympatric and behavioral differences of domestic and sylvatic TcI strains; the clinical and epidemiological implications are herein discussed. PMID:25461848

  3. Comparative Packaging Study

    NASA Technical Reports Server (NTRS)

    Perchonok, Michele; Antonini, David

    2008-01-01

    This viewgraph presentation describes a comparative packaging study for use on long duration space missions. The topics include: 1) Purpose; 2) Deliverables; 3) Food Sample Selection; 4) Experimental Design Matrix; 5) Permeation Rate Comparison; and 6) Packaging Material Information.

  4. Comparing different approaches to visualizing light waves: An experimental study on teaching wave optics

    NASA Astrophysics Data System (ADS)

    Mešić, Vanes; Hajder, Erna; Neumann, Knut; Erceg, Nataša

    2016-06-01

    Research has shown that students have tremendous difficulties developing a qualitative understanding of wave optics, at all educational levels. In this study, we investigate how three different approaches to visualizing light waves affect students' understanding of wave optics. In the first, the conventional, approach light waves are represented by sinusoidal curves. The second teaching approach includes representing light waves by a series of static images, showing the oscillating electric field vectors at characteristic, subsequent instants of time. Within the third approach phasors are used for visualizing light waves. A total of N =85 secondary school students were randomly assigned to one of the three teaching approaches, each of which lasted a period of four class hours. Students who learned with phasors and students who learned from the series of static images outperformed the students learning according to the conventional approach, i.e., they showed a much better understanding of basic wave optics, as measured by a conceptual survey administered to the students one week after the treatment. Our results suggest that visualizing light waves with phasors or oscillating electric field vectors is a promising approach to developing a deeper understanding of wave optics for students enrolled in conceptual level physics courses.

  5. A comparative experimental study of the organization of arterial and venous thrombi.

    PubMed Central

    Usui, Y; Sauvage, L R; Wu, H D; Goff, S G; Walker, M

    1987-01-01

    Organization of a venous thrombus proceeds much faster than that of an arterial thrombus. Two different double-ligation procedures were used for study of the time sequence of thrombus organization by the vascularized (in situ) and devascularized (dissected) walls of the external jugular vein and common carotid artery in 21 mongrel dogs. Blood in the ligated segments of the in situ veins remained mostly fluid. In these segments, intimal hyperplasia was observed after 4 weeks with apparent preservation of an endothelial lining. However, in the dissected veins, the trapped blood rapidly thrombosed. Remarkable cell proliferation quickly occurred in these dissected walls with rapid invasion of the thrombus to achieve complete organization by 4 weeks. In contrast, a thrombus formed in the ligated segments of all arteries, whether in situ or dissected, and organization was much slower, requiring about 4 months for completion. Full-wall viability was maintained in 100% of the in situ veins and in 95% of the devascularized veins, but inner wall viability was lost in 30% of the in situ arteries and in 95% of the devascularized arteries. Images Figs. 1A and B. Figs. 3A-C. Figs. 4A-D. Figs. 5A-C. Figs. 6A-D. Figs. 7A-F. PMID:3827364

  6. Carbon fiber based composites stress analysis. Experimental and computer comparative studies

    NASA Astrophysics Data System (ADS)

    Sobek, M.; Baier, A.; Buchacz, A.; Grabowski, Ł.; Majzner, M.

    2015-11-01

    Composite materials used nowadays for the production of composites are the result of advanced research. This allows assuming that they are among the most elaborate tech products of our century. That fact is evidenced by the widespread use of them in the most demanding industries like aerospace and space industry. But the heterogeneous materials and their advantages have been known to mankind in ancient times and they have been used by nature for millions of years. Among the fibers used in the industry most commonly used are nylon, polyester, polypropylene, boron, metal, glass, carbon and aramid. Thanks to their physical properties last three fiber types deserve special attention. High strength to weight ratio allow the use of many industrial solutions. Composites based on carbon and glass fibers are widely used in the automotive. Aramid fibers ideal for the fashion industry where the fabric made from the fibers used to produce the protective clothing. In the paper presented issues of stress analysis of composite materials have been presented. The components of composite materials and principles of composition have been discussed. Particular attention was paid to the epoxy resins and the fabrics made from carbon fibers. The article also includes basic information about strain measurements performed on with a resistance strain gauge method. For the purpose of the laboratory tests a series of carbon - epoxy composite samples were made. For this purpose plain carbon textile was used with a weight of 200 g/mm2 and epoxy resin LG730. During laboratory strain tests described in the paper Tenmex's delta type strain gauge rosettes were used. They were arranged in specific locations on the surface of the samples. Data acquisition preceded using HBM measurement equipment, which included measuring amplifier and measuring head. Data acquisition was performed using the Easy Catman. In order to verify the results of laboratory tests numerical studies were carried out in a

  7. Comparative studies on shielding properties of some steel alloys using Geant4, MCNP, WinXCOM and experimental results

    NASA Astrophysics Data System (ADS)

    Singh, Vishwanath P.; Medhat, M. E.; Shirmardi, S. P.

    2015-01-01

    The mass attenuation coefficients, μ/ρ and effective atomic numbers, Zeff of some carbon steel and stainless steel alloys have been calculated by using Geant4, MCNP simulation codes for different gamma ray energies, 279.1 keV, 661.6 keV, 662 keV, 1115.5 keV, 1173 keV and 1332 keV. The simulation results of Zeff using Geant4 and MCNP codes have been compared with possible available experimental results and theoretical WinXcom, and good agreement has been observed. The simulated μ/ρ and Zeff values using Geant4 and MCNP code signifies that both the simulation process can be followed to determine the gamma ray interaction properties of the alloys for energies wherever analogous experimental results may not be available. This kind of studies can be used for various applications such as for radiation dosimetry, medical and radiation shielding.

  8. Comparative studies between theoretical and experimental of elastic properties and irradiation effects of soda lime glasses doped with neodymium oxide

    NASA Astrophysics Data System (ADS)

    Bootjomchai, C.

    2015-05-01

    A comparative studies on the theoretical and experimental values of elastic moduli of (90 - x) RWG -(10)Na2O -(x)Nd2O3 glass system, where RWG is recycled window glass and x is 0.001, 0.01, 0.1 and 1 mol%, was investigated. The radiation effects on structural properties and elastic moduli were evaluated by measuring the ultrasonic velocities. In addition, the FTIR spectra were measured to investigate the effects of irradiation on the structure of the glass. Moreover, the theoretical bond compression model was used to confirm the obtained results from the experiments. The results show that evidently changes in the structure of the glass depend on the concentration of the neodymium oxide and gamma irradiation. Furthermore, the experimental elastic moduli are in good agreement with the theoretical values.

  9. A Comparative Study of Information-Based Source Number Estimation Methods and Experimental Validations on Mechanical Systems

    PubMed Central

    Cheng, Wei; Zhang, Zhousuo; Cao, Hongrui; He, Zhengjia; Zhu, Guanwen

    2014-01-01

    This paper investigates one eigenvalue decomposition-based source number estimation method, and three information-based source number estimation methods, namely the Akaike Information Criterion (AIC), Minimum Description Length (MDL) and Bayesian Information Criterion (BIC), and improves BIC as Improved BIC (IBIC) to make it more efficient and easier for calculation. The performances of the abovementioned source number estimation methods are studied comparatively with numerical case studies, which contain a linear superposition case and a both linear superposition and nonlinear modulation mixing case. A test bed with three sound sources is constructed to test the performances of these methods on mechanical systems, and source separation is carried out to validate the effectiveness of the experimental studies. This work can benefit model order selection, complexity analysis of a system, and applications of source separation to mechanical systems for condition monitoring and fault diagnosis purposes. PMID:24776935

  10. Functional characterization of α1-adrenoceptor subtypes in vascular tissues using different experimental approaches:a comparative study

    PubMed Central

    Gisbert, Regina; Madrero, Yolanda; Sabino, Valentina; Noguera, M Antonia; Ivorra, M Dolores; D'Ocon, Pilar

    2003-01-01

    The α1-adrenergic responses of rat aorta and tail artery have been analysed measuring the contractility and the inositol phosphate (IP) formation induced by noradrenaline. Three antagonists, prazosin, 5-methylurapidil (α1A selective) and BMY 7378 (α1D selective) have been used in different experimental procedures. Noradrenaline possesses a greater potency inducing contraction and IP accumulation in aorta (pEC50-contraction=7.32±0.04; pEC50-IPs=6.03±0.08) than in the tail artery (pEC50-contraction=5.71±0.07; pEC50-IPs=5.51±0.10). Although the maximum contraction was similar in both tissues (Emax-tail=619.1±55.6 mg; Emax-aorta-698.2±40.8 mg), there were marked differences in the ability of these tissues to generate intracellular second messengers the tail artery being more efficient (Emax-tail=1060±147%; Emax-aorta=108.1±16.9%). Concentration response curves of noradrenaline in presence of antagonist together with concentration inhibition curves for antagonists added before (CICb) or after (CICa) noradrenaline-induced maximal response in Ca2+-containing or Ca2+-free medium have been performed. A comparative analysis of the different procedures as well as the mathematical approaches used in each case to calculate the antagonist potencies, were completed. The CICa was the simplest method to characterize the predominant α1-adrenoceptor subtype involved in the functional response of a tissue. In aorta, where constitutively active α1D-adrenoeptors are present, the use of different experimental procedures evidenced a complex equilibrium between α1D- and α1A-adrenoceptor subtypes. The appropriate management of LiCl in IP accumulation studies allowed us to reproduce the different experimental procedures performed in contractile experiments giving more technical possibilities to this methodology. PMID:12540527

  11. A randomized controlled experimental study comparing chitosan coated polypropylene mesh and Proceed™ mesh for abdominal wall defect closure

    PubMed Central

    Jayanth, S.T.; Pulimood, Anna; Abraham, Deepak; Rajaram, A.; Paul, M.J.; Nair, Aravindan

    2015-01-01

    Background Abdominal wall defects and hernias are commonly repaired with synthetic or biological materials. Adhesions and recurrences are a common problem. A study was conducted to compare Chitosan coated polypropylene mesh and a polypropylene–polydioxanone composite with oxidized cellulose coating mesh (Proceed™) in repair of abdominal wall defect in a Rabbit hernia model. Methods A randomized controlled experimental study was done on twelve New Zealand white rabbits. A ventral abdominal defect was created in each of the rabbits. The rabbits were divided into two groups. In one group the defect was repaired with Chitosan coated polypropylene mesh and Proceed mesh™ in the other. The rabbits were operated in two phases. They were followed up at four weeks and twelve weeks respectively after which the rabbits were sacrificed. They were evaluated by open exploration and histopathological examination. Their efficacy in reducing adhesion and ability of remodeling and tissue integration were studied. Results There was no statistical significance in the area of adhesion, the force required to remove the adhesions, tissue integration and remodeling between Chitosan and Proceed™ group. Histological analysis revealed that the inflammatory response, fibrosis, material degradation and remodeling were similar in both the groups. There were no hernias, wound infection or dehiscence in any of the studied animals. Conclusion Chitosan coated polypropylene mesh was found to have similar efficacy to Proceed™ mesh. Chitosan coated polypropylene mesh, can act as an anti adhesive barrier when used in the repair of incisional hernias and abdominal wall defects. PMID:26594357

  12. A comparative experimental and quantum chemical study on monomeric and dimeric structures of 3,5-dibromoanthranilic acid

    NASA Astrophysics Data System (ADS)

    Karabacak, Mehmet; Cinar, Mehmet

    2012-10-01

    This study presents the structural and spectroscopic characterization of 3,5-dibromoanthranilic acid with help of experimental techniques (FT-IR, FT-Raman, UV, NMR) and quantum chemical calculations. The vibrational spectra of title compound were recorded in solid state with FT-IR and FT-Raman in the range of 4000-400 and 4000-50 cm-1, respectively. The vibrational frequencies were also computed using B3LYP method of DFT with 6-311++G(d,p) basis set. The fundamental assignments were done on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The 1H, 13C and DEPT NMR spectra were recorded in DMSO solution and calculated by gauge-invariant atomic orbitals (GIAO) method. The UV absorption spectra of the compound were recorded in the range of 200-400 nm in ethanol, water and DMSO solutions. Solvent effects were calculated using time-dependent density functional theory and CIS method. The ground state geometrical structure of compound was predicted by B3LYP method and compared with the crystallographic structure of similar compounds. All calculations were made for monomeric and dimeric structure of compound. Moreover, molecular electrostatic potential (MEP) and thermodynamic properties were performed. Mulliken atomic charges of neutral and anionic form of the molecule were computed and compared with anthranilic acid.

  13. A comparative experimental and quantum chemical study on monomeric and dimeric structures of 3,5-dibromoanthranilic acid.

    PubMed

    Karabacak, Mehmet; Cinar, Mehmet

    2012-10-01

    This study presents the structural and spectroscopic characterization of 3,5-dibromoanthranilic acid with help of experimental techniques (FT-IR, FT-Raman, UV, NMR) and quantum chemical calculations. The vibrational spectra of title compound were recorded in solid state with FT-IR and FT-Raman in the range of 4000-400 and 4000-50 cm(-1), respectively. The vibrational frequencies were also computed using B3LYP method of DFT with 6-311++G(d,p) basis set. The fundamental assignments were done on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The (1)H, (13)C and DEPT NMR spectra were recorded in DMSO solution and calculated by gauge-invariant atomic orbitals (GIAO) method. The UV absorption spectra of the compound were recorded in the range of 200-400 nm in ethanol, water and DMSO solutions. Solvent effects were calculated using time-dependent density functional theory and CIS method. The ground state geometrical structure of compound was predicted by B3LYP method and compared with the crystallographic structure of similar compounds. All calculations were made for monomeric and dimeric structure of compound. Moreover, molecular electrostatic potential (MEP) and thermodynamic properties were performed. Mulliken atomic charges of neutral and anionic form of the molecule were computed and compared with anthranilic acid. PMID:22871548

  14. Prevention praised, cure preferred: results of between-subjects experimental studies comparing (monetary) appreciation for preventive and curative interventions

    PubMed Central

    2013-01-01

    Background 'An ounce of prevention is worth a pound of cure’ is a common saying, and indeed, most health economic studies conclude that people are more willing to pay for preventive measures than for treatment activities. This may be because most health economic studies ask respondents to compare preventive measures with treatment, and thus prompt respondents to consider other uses of resources. However, psychological theorizing suggests that, when methods do not challenge subjects to consider other uses of resources, curative treatment is favored over prevention. Could it be that while prevention is praised, cure is preferred? Methods In two experimental studies, we investigated, from a psychological perspective and using a between-subjects design, whether prevention or treatment is preferred and why. In both studies, participants first read a lung cancer prevention or treatment intervention scenario that varied on the prevention-treatment dimension, but that were the same on factors like 'costs per saved life’ and kind of disease. Then participants completed a survey measuring appreciation (general and monetary) as well as a number of potential mediating variables. Results Both studies clearly demonstrated that, when the design was between-subjects, participants had greater (general and monetary) appreciation for treatment interventions than for preventive interventions with perceived urgency of the intervention quite consistently mediating this effect. Differences in appreciation of treatment over preventive treatment were shown to be .59 (Study 1) and .45 (Study 2) on a 5-point scale. Furthermore, participants thought that health insurance should compensate more for the treatment than for preventive measures, differences of 16% (Study 1), and 22% (Study 2). When participants were asked to directly compare both interventions on the basis of a short description, they preferred the preventive intervention. Conclusion It appears that people claim to prefer

  15. Accuracy and Precision of Three-Dimensional Low Dose CT Compared to Standard RSA in Acetabular Cups: An Experimental Study.

    PubMed

    Brodén, Cyrus; Olivecrona, Henrik; Maguire, Gerald Q; Noz, Marilyn E; Zeleznik, Michael P; Sköldenberg, Olof

    2016-01-01

    Background and Purpose. The gold standard for detection of implant wear and migration is currently radiostereometry (RSA). The purpose of this study is to compare a three-dimensional computed tomography technique (3D CT) to standard RSA as an alternative technique for measuring migration of acetabular cups in total hip arthroplasty. Materials and Methods. With tantalum beads, we marked one cemented and one uncemented cup and mounted these on a similarly marked pelvic model. A comparison was made between 3D CT and standard RSA for measuring migration. Twelve repeated stereoradiographs and CT scans with double examinations in each position and gradual migration of the implants were made. Precision and accuracy of the 3D CT were calculated. Results. The accuracy of the 3D CT ranged between 0.07 and 0.32 mm for translations and 0.21 and 0.82° for rotation. The precision ranged between 0.01 and 0.09 mm for translations and 0.06 and 0.29° for rotations, respectively. For standard RSA, the precision ranged between 0.04 and 0.09 mm for translations and 0.08 and 0.32° for rotations, respectively. There was no significant difference in precision between 3D CT and standard RSA. The effective radiation dose of the 3D CT method, comparable to RSA, was estimated to be 0.33 mSv. Interpretation. Low dose 3D CT is a comparable method to standard RSA in an experimental setting. PMID:27478832

  16. Accuracy and Precision of Three-Dimensional Low Dose CT Compared to Standard RSA in Acetabular Cups: An Experimental Study

    PubMed Central

    Olivecrona, Henrik; Maguire, Gerald Q.; Noz, Marilyn E.; Zeleznik, Michael P.

    2016-01-01

    Background and Purpose. The gold standard for detection of implant wear and migration is currently radiostereometry (RSA). The purpose of this study is to compare a three-dimensional computed tomography technique (3D CT) to standard RSA as an alternative technique for measuring migration of acetabular cups in total hip arthroplasty. Materials and Methods. With tantalum beads, we marked one cemented and one uncemented cup and mounted these on a similarly marked pelvic model. A comparison was made between 3D CT and standard RSA for measuring migration. Twelve repeated stereoradiographs and CT scans with double examinations in each position and gradual migration of the implants were made. Precision and accuracy of the 3D CT were calculated. Results. The accuracy of the 3D CT ranged between 0.07 and 0.32 mm for translations and 0.21 and 0.82° for rotation. The precision ranged between 0.01 and 0.09 mm for translations and 0.06 and 0.29° for rotations, respectively. For standard RSA, the precision ranged between 0.04 and 0.09 mm for translations and 0.08 and 0.32° for rotations, respectively. There was no significant difference in precision between 3D CT and standard RSA. The effective radiation dose of the 3D CT method, comparable to RSA, was estimated to be 0.33 mSv. Interpretation. Low dose 3D CT is a comparable method to standard RSA in an experimental setting. PMID:27478832

  17. An Experimental Study Comparing English-Only and Transitional Bilingual Education on Spanish-Speaking Preschoolers' Early Literacy Development

    ERIC Educational Resources Information Center

    Duran, Lillian K.; Roseth, Cary J.; Hoffman, Patricia

    2010-01-01

    A longitudinal, experimental-control design was used to test the hypothesis that native language instruction enhances English language learner's (ELL's) native language and literacy development without significant cost to English development. In this study, 31 Spanish-speaking preschoolers (aged 38-48 months) were randomly assigned to two Head…

  18. Comparative Financial Statistics for Public Community and Junior Colleges, 1980-81: An Experimental Study of 420 Institutions.

    ERIC Educational Resources Information Center

    Dickmeyer, Nathan; Cirino, Anna Marie

    This report, the fourth in a series of comparative data studies of public community and junior colleges in the United States, presents information derived from a sample of 420 colleges. After introductory material presents background on the study and its objectives, chapter 1 outlines possible uses of the study data, points out limitations and the…

  19. Comparing theory with experimental data in studying the deformation of magnetically smart films deposited on nickel and glass substrates

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoli; Cao, Jian; Ulmer, M. P.; Graham, M. E.; Vaynman, S.; Savoie, J.; Bellavia, B.

    2012-10-01

    This paper will present the procedure of measuring the deformation of the magnetostrictive bimorph specimens under an applied external magnetic field, and the theoretical and numerical analysis of the deformation. The magnetically smart material (MSM) KelvinAllTM and Terfenol-D is deposited on the nickel or glass substrates. The profiles of thin-film specimens were measured under an external magnetic field with White Light Interferometry. Using the theoretical calculation, the magnetostrictive property was evaluated for the coated Ni sample and glass sample. Employing the numerical approach, the influence of the magnetostrictive film on the deformation of the sample was simulated and compared with experimental results. The coated Ni specimen exhibited larger deformation than the coated glass specimen when the specimen is immersed in a 0.16 T magnetic field. In our experiments, the residual stress calculated in the thin film of the bimorph is acceptable and could be decreased by changing the parameters in the specimen preparation process. The experimental results in this paper was employed as the preliminary step to realize the future application of the magnetostrictive thin film bimorph to the adaptive X-ray mirror, and the theoretical and numerical approach was used to predict the influence of the magnetostrictive film on the larger mirror surface deformation.

  20. A comparative study between experimental results and numerical predictions of multi-wall structural response to hypervelocity impact

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.; Peck, Jeffrey A.

    1992-01-01

    Over the last three decades, multiwall structures have been analyzed extensively, primarily through experiment, as a means of increasing the protection afforded to spacecraft structure. However, as structural configurations become more varied, the number of tests required to characterize their response increases dramatically. As an alternative, numerical modeling of high-speed impact phenomena is often being used to predict the response of a variety of structural systems under impact loading conditions. This paper presents the results of a preliminary numerical/experimental investigation of the hypervelocity impact response of multiwall structures. The results of experimental high-speed impact tests are compared against the predictions of the HULL hydrodynamic computer code. It is shown that the hypervelocity impact response characteristics of a specific system cannot be accurately predicted from a limited number of HULL code impact simulations. However, if a wide range of impact loadings conditions are considered, then the ballistic limit curve of the system based on the entire series of numerical simulations can be used as a relatively accurate indication of actual system response.

  1. Radical species in the cool-flame regime of diesel combustion: a comparative numerical and experimental study

    NASA Astrophysics Data System (ADS)

    Costa, M.; Vaglieco, B. M.; Corcione, F. E.

    2005-09-01

    Multidimensional modelling and experimental measurements are performed to study the early stages of diesel combustion. Numerical simulation is realised by means of a customised version of the KIVA 3 code, including the Shell model for auto-ignition. Experimentally, a spectroscopic analysis of the burning mixture is carried out under real operating conditions on a diesel engine equipped with an optically accessible combustion chamber. Changing the fuel injection law makes for auto-ignition to occur in environments characterised by different values of mixture pressure and temperature. Dependence of the ignition delay time upon this last variable is shown to follow a law with a negative temperature coefficient in the middle range of values. By means of natural chemiluminescence spectra, OH, CH and HCO radicals are detected as products of the reactions of thermal decomposition of the hydrocarbon molecules preceding auto-ignition. Distribution of the radicals’ emission intensity within the combustion chamber permits the localisation of auto-ignition sites. These are found to be in good agreement with the points of high energetic chemical activity, individuated numerically, under all the considered operating conditions. Experimentally identified radicals and fictitious species entering the reduced kinetic scheme employed within the numerical simulation are shown to exhibit an analogous behaviour regarding the trend with respect to time of the total amount of concentration, and, in a spatial sense, their distribution within the combustion chamber at the time of auto-ignition.

  2. [Comparative animal experimental study on the importance of the surface structure for the stability of extension implantations].

    PubMed

    Dördelmann, K; Tetsch, P; Ibing, G

    1977-04-01

    An animal experimental study was undertaken where the embedding of extension implants with a smooth or porous surface was histologically examined. Under extreme functional stress there occurs a mobility of the implants with the formation of a broad connective tissue zone, inflammatory reactions and ingrowth of epithelium, which is independent of the surface structure. Implants under less stress show a narrower connective tissue layer which narrows itself further if the surface is porous. The possible causes of this tissue reaction are discussed. PMID:266991

  3. Identification of structural and spectral features of synthesized cyano-stilbene dye derivatives: a comparative experimental and DFT study.

    PubMed

    Karabacak, M; Asiri, A M; Al-Youbi, A O; Qusti, A H; Cinar, M

    2014-01-01

    The synthesized three dye derivatives of cyano-stilbene monomer were identified by experimental spectroscopic techniques and density functional approach. The optimized geometrical structure, vibrational and electronic transitions along with the nonlinear optical (NLO) properties of those compounds were presented in this study. The vibrational spectra of investigated compounds were recorded in solid state with FT-IR and FT-Raman spectrometry in the range of 4000-400 cm(-1) and 3600-50 cm(-1), respectively. The theoretical ground state equilibrium conformations and vibrational wavenumbers were carried out by using density functional method with 6-311G(d,p) basis set. Assignments of the fundamental vibrational modes were examined on the basis of the measured data and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The UV absorption spectra of monomers were observed in the range of 200-600 nm in chloroform, acetonitrile and toluene, and time dependent DFT method was used to obtain the electronic properties. The linear polarizability and first hyperpolarizability of the studied molecules indicates that the title compounds can be used as a good nonlinear optical material. A detailed description of spectroscopic behaviors of compounds was given based on the comparison of experimental measurements and theoretical computations. PMID:24177881

  4. Molecular and intermolecular effects in collagen fibril mechanics: a multiscale analytical model compared with atomistic and experimental studies.

    PubMed

    Marino, Michele

    2016-02-01

    Both atomistic and experimental studies reveal the dependence of collagen fibril mechanics on biochemical and biophysical features such as, for instance, cross-link density, water content and protein sequence. In order to move toward a multiscale structural description of biological tissues, a novel analytical model for collagen fibril mechanics is herein presented. The model is based on a multiscale approach that incorporates and couples: thermal fluctuations in collagen molecules; the uncoiling of collagen triple helix; the stretching of molecular backbone; the straightening of the telopeptide in which covalent cross-links form; slip-pulse mechanisms due to the rupture of intermolecular weak bonds; molecular interstrand delamination due to the rupture of intramolecular weak bonds; the rupture of covalent bonds within molecular strands. The effectiveness of the proposed approach is verified by comparison with available atomistic results and experimental data, highlighting the importance of cross-link density in tuning collagen fibril mechanics. The typical three-region shape and hysteresis behavior of fibril constitutive response, as well as the transition from a yielding-like to a brittle-like behavior, are recovered with a special insight on the underlying nanoscale mechanisms. The model is based on parameters with a clear biophysical and biochemical meaning, resulting in a promising tool for analyzing the effect of pathological or pharmacological-induced histochemical alterations on the functional mechanical response of collagenous tissues. PMID:26220454

  5. Comparative experimental and theoretical studies of N-(4-Methylbenzylidene)-N'-(2-carboxyphenyl) hydrazine novel Schiff base.

    PubMed

    Tunç, Tuncay; Tezcan, Habibe; Sağlam, Semran; Dilek, Nefise

    2014-06-01

    In this work, N-(4-Methylbenzylidene)-N'-(2-carboxyphenyl) hydrazine, C15H14N2O2, Schiff base molecule has been synthesized and characterized by elemental analyses, UV-Vis and IR spectroscopy and single crystal X-ray determination. The molecule of the title compound adopt an E configuration about the azomethine CN double bond. The benzene and phenyl rings are planar and the dihedral angle between the planes is 7.2(2)°. The crystal structure is stabilized by intermolecular OH⋯O and intramoleculer NH⋯O hydrogen bonding interactions. X-ray diffraction analyses show that, N-(4-Methylbenzylidene)-N'-(2-carboxyphenyl) hydrazine Schiff base molecule crystallizes in the monoclinic system, P21/c space group, a=4.392(5)Å, b=22.340(5)Å, c=13.528(5)Å, β=92.882(5)°, V=1325.7(16)Å(3), Z=4. The conformational analysis of N-(4-Methylbenzylidene)-N'-(2-carboxyphenyl) hydrazine was performed by the density functional theory (DFT) B3LYP method using the 6-311++G(d,p) basis set. Also, theoretical values of FTIR and UV-Vis were performed by the same method. The calculated geometry parameters, IR and UV-Vis results were compared with experimental results. PMID:24657931

  6. Cooperative Learning, Motivational Effects, and Student Characteristics: An Experimental Study Comparing Cooperative Learning and Direct Instruction in 12th Grade Physics Classes

    ERIC Educational Resources Information Center

    Hanze, Martin; Berger, Roland

    2007-01-01

    One hundred thirty-seven students in 12th grade physics classes participated in a quasi-experimental study comparing the jigsaw classroom method of cooperative instruction with traditional direct instruction. While no differences were found between the two conditions for physics achievement gains, the results revealed differences in students'…

  7. Physiologic Responses to Infrarenal Aortic Cross-Clamping during Laparoscopic or Conventional Vascular Surgery in Experimental Animal Model: Comparative Study

    PubMed Central

    Martín-Cancho, María F.; Crisóstomo, Verónica; Soria, Federico; Calles, Carmen; Sánchez-Margallo, Francisco M.; Díaz-Güemes, Idoia; Usón-Gargallo, Jesús

    2008-01-01

    The aim of this study was to compare the hemodynamic and ventilatory effects of prolonged infrarenal aortic cross-clamping in pigs undergoing either laparotomy or laparoscopy. 18 pigs were used for this study. Infrarenal aortic crossclamping was performed for 60 minutes in groups I (laparotomy, n = 6) and II (laparoscopy, n = 6). Group III (laparoscopy, n = 6) underwent a 120-minute long pneumoperitoneum in absence of aortic clamping (sham group). Ventilatory and hemodynamic parameters and renal function were serially determined in all groups. A significant decrease in pH and significant increase in PaCO2 were observed in group II, whereas no changes in these parameters were seen in group I and III. All variables returned to values similar to baseline in groups I and II 60 minutes after declamping. A significant increase in renal resistive index was evidenced during laparoscopy, with significantly higher values seen in Group II. Thus a synergic effect of pneumoperitoneum and aortic cross-clamping was seen in this study. These two factors together cause decreased renal perfusion and acidosis, thus negatively affecting the patient's general state during this type of surgery. PMID:21197458

  8. Experimental investigations on flashing-induced instabilities in one and two-parallel channels: A comparative study

    SciTech Connect

    Marcel, Christian P.; Rohde, M.; Van Der Hagen, T.H.J.J.

    2010-10-15

    In this investigation, experiments conducted in a natural circulation test facility at low power and low pressure conditions, in the one single and two-parallel channels configuration are presented and discussed in detail. The novel manner of visualizing the results allowed characterizing the facility at any time and position which helped to thoroughly understand the instability mechanisms. Different modes were observed for each configuration. In the case of having two-parallel channels, four different behaviors have been observed: stable flow circulation, periodic high subcooling oscillations, a-periodical oscillations and out-of-phase periodical oscillations. In addition, stability maps were constructed in order to clarify the region in which each mode is dominant. The results obtained from both the one and two-parallel channels configurations are thus analyzed and compared. As a result, some similarities have been observed between the intermittent flow oscillations found in the single channel experiments and the high subcooling oscillations found in the two-parallel channels experiments. Moreover, similarities have also been found between the sinusoidal flow oscillations existing in the single channel experiments and the out-of-phase oscillations from the two-parallel channels experiments. The experiments presented in this work can be used to benchmark numerical codes and modeling techniques developed to study the start-up of natural circulation BWRs. (author)

  9. Comparative Financial Statistics for Public Community and Junior Colleges, 1981-82: An Experimental Study of 442 Institutions.

    ERIC Educational Resources Information Center

    Dickmeyer, Nathan; Cirino, Anna Marie

    Drawing from two surveys of 442 public community and junior colleges from across the country, this report presents comparative financial statistics for 1981-82. Chapter 1 provides information on the use of the report in comparing institutional statistics with national and peer group medians; points out limitations of the data; and offers a summary…

  10. Comparative Financial Statistics for Public Community and Junior Colleges, 1982-83: An Experimental Study of 520 Institutions.

    ERIC Educational Resources Information Center

    Dickmeyer, Nathan; Cirino, Anna Marie

    Drawing from two surveys of 520 public community and junior colleges from across the country, this report presents comparative financial statistics for 1982-83. Chapter 1 provides information on the use of the report in comparing institutional statistics with national and peer group medians; points out limitations of the data; and offers a summary…

  11. Comparative Financial Statistics for Public Community and Junior Colleges, 1983-84: An Experimental Study of 560 Institutions.

    ERIC Educational Resources Information Center

    Dickmeyer, Nathan; Cirino, Anna Marie

    Comparative financial information for fiscal year (FY) 1983-84 is presented in this report, derived from two surveys of a sample of 560 public community and junior colleges. Chapter 1 provides guidance on the use of the report in comparing institutional statistics with national and peer group medians; points out limitations of the data; and…

  12. Comparative Financial Statistics for Public Community and Junior Colleges, 1984-85: An Experimental Study of 545 Institutions.

    ERIC Educational Resources Information Center

    Dickmeyer, Nathan; Cirino, Anna Marie

    Drawing from two surveys of 545 public community and junior colleges from across the country, this report presents comparative financial statistics for fiscal year (FY) 1984-85. Chapter 1 provides information on the use of the report in comparing institutional statistics with national and peer group medians; points out limitations of the data; and…

  13. Modeling defect cluster evolution in irradiated structural materials: Focus on comparing to high-resolution experimental characterization studies

    SciTech Connect

    Wirth, Brian D.; Hu, Xunxiang; Kohnert, Aaron; Xu, Donghua

    2015-03-02

    Exposure of metallic structural materials to irradiation environments results in significant microstructural evolution, property changes, and performance degradation, which limits the extended operation of current generation light water reactors and restricts the design of advanced fission and fusion reactors. Further, it is well recognized that these irradiation effects are a classic example of inherently multiscale phenomena and that the mix of radiation-induced features formed and the corresponding property degradation depend on a wide range of material and irradiation variables. This inherently multiscale evolution emphasizes the importance of closely integrating models with high-resolution experimental characterization of the evolving radiation-damaged microstructure. Lastly, this article provides a review of recent models of the defect microstructure evolution in irradiated body-centered cubic materials, which provide good agreement with experimental measurements, and presents some outstanding challenges, which will require coordinated high-resolution characterization and modeling to resolve.

  14. Modeling defect cluster evolution in irradiated structural materials: Focus on comparing to high-resolution experimental characterization studies

    DOE PAGESBeta

    Wirth, Brian D.; Hu, Xunxiang; Kohnert, Aaron; Xu, Donghua

    2015-03-02

    Exposure of metallic structural materials to irradiation environments results in significant microstructural evolution, property changes, and performance degradation, which limits the extended operation of current generation light water reactors and restricts the design of advanced fission and fusion reactors. Further, it is well recognized that these irradiation effects are a classic example of inherently multiscale phenomena and that the mix of radiation-induced features formed and the corresponding property degradation depend on a wide range of material and irradiation variables. This inherently multiscale evolution emphasizes the importance of closely integrating models with high-resolution experimental characterization of the evolving radiation-damaged microstructure. Lastly,more » this article provides a review of recent models of the defect microstructure evolution in irradiated body-centered cubic materials, which provide good agreement with experimental measurements, and presents some outstanding challenges, which will require coordinated high-resolution characterization and modeling to resolve.« less

  15. Comparing fluid mechanics models with experimental data.

    PubMed Central

    Spedding, G R

    2003-01-01

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

  16. "It's Harder Than We Thought It Would Be": A Comparative Case Study of Expert-Novice Experimentation Strategies.

    ERIC Educational Resources Information Center

    Hmelo-Silver, Cindy E.; Nagarajan, Anandi; Day, Roger S.

    2002-01-01

    Compares a group of expert cancer researchers with four groups of fourth year medical students (the "novice" groups) engaged in the task of designing a clinical trial to test a new cancer drug using a computer-based modeling tool, the Oncology Thinking Cap. (Contains 24 references.) (Author/YDS)

  17. [Incus, controlled deepfrozen or in cialit conserved, after allogenetic implantation. An animal-experimental study with comparing histology (author's transl)].

    PubMed

    Eitschberger, E; Heine, W D; Waller, W; Gammert, C

    1977-07-29

    The histological reactions to the implantation of allogenetic incus after conservation in Cialit or after controlled deepfreezing are described. After 5 months the incusses of both conservation technics show the same good tendency of revitalisation. Therefore the controlled deep-freezing technic does not offer an advantage compared to the Cialit conservation method at least for the present state of knowledge. PMID:578732

  18. A study to evaluate the efficacy of xylene-free hematoxylin and eosin staining procedure as compared to the conventional hematoxylin and eosin staining: An experimental study

    PubMed Central

    Ankle, Madhuri R; Joshi, Priya S

    2011-01-01

    Context: Use of diluted dish washing solution (DWS) has been experimented successfully as a substitute for xylene to deparaffinize tissue sections during hematoxylin and eosin (H and E) staining. Aims: (1) Test the hypothesis that xylene- and methanol-free sections (XMF) deparaffinized with diluted DWS are better than or at par with conventional H and E sections. (2) To compare the efficacy of xylene-free sections with the conventional H and E sections. Settings and Design: Single blinded experimental study. Materials and Methods: Sixty paraffin blocks were considered. One section was stained with conventional H and E method (Group A) and the other with XMF H and E (Group B). Slides were scored for parameters; nuclear staining, cytoplasmic staining (adequate = score1, inadequate = score0), uniformity, clarity, crispness (present = score1, absent = score0). Score >/= 2 was inadequate for diagnosis and 3-5 was adequate for diagnosis. Statistical analysis used: Z test. Results: Adequate nuclear staining, 96.66% sections in group A and 98.33% in Group B (Z = 0.59, P>0.05); adequate cytoplasmic staining, 93.33% in group A and 83.33% in Group B (Z = 1.97, P<0.05); uniform staining, 70% in group A, 50% in group B (Z = 1.94, P<0.05), clarity present in 85% of group A, 88.33% of group B sections (Z = 0.27, P>0.05), crisp staining in 76.66% in group A and 83.33% in Group B (Z = 1.98, P<0.05), 88.33% Group A sections stained adequately for diagnosis as compared with 90% in Group B (Z = 0.17, P>0.05). Conclusion: Xylene- and methanol-free H and E staining is a better alternative to the conventional H and E staining procedure. PMID:22529574

  19. "Clickers" and Metacognition: A Quasi-Experimental Comparative Study about Metacognitive Self-Regulation and Use of Electronic Feedback Devices

    ERIC Educational Resources Information Center

    Brady, Melanie; Seli, Helena; Rosenthal, Jane

    2013-01-01

    The purpose of this study was to establish whether electronic response systems (clickers) influence student metacognition in large lecture settings more than low-technology polling devices. In this first part of a two part mixed methods study inquiry was made into whether student metacognition was influenced and how metacognition was influenced.…

  20. Improved Titanium Billet Inspection Sensitivity through Optimized Phased Array Design, Part II: Experimental Validation and Comparative Study with Multizone

    SciTech Connect

    Hassan, W.; Vensel, F.; Knowles, B.

    2006-03-06

    The inspection of critical rotating components of aircraft engines has made important advances over the last decade. The development of Phased Array (PA) inspection capability for billet and forging materials used in the manufacturing of critical engine rotating components has been a priority for Honeywell Aerospace. The demonstration of improved PA inspection system sensitivity over what is currently used at the inspection houses is a critical step in the development of this technology and its introduction to the supply base as a production inspection. As described in Part I (in these proceedings), a new phased array transducer was designed and manufactured for optimal inspection of eight inch diameter Ti-6Al-4V billets. After confirming that the transducer was manufactured in accordance with the design specifications a validation study was conducted to assess the sensitivity improvement of the PAI over the current capability of Multi-zone (MZ) inspection. The results of this study confirm the significant ({approx_equal} 6 dB in FBH number sign sensitivity) improvement of the PAI sensitivity over that of MZI.

  1. Biocompatibility of Ricinus communis polymer with addition of calcium carbonate compared to titanium. Experimental study in guinea pigs

    PubMed Central

    Graça, Yorgos Luiz Santos De Salles; Opolski, Ana Cristina; Barboza, Barbara Evelin Gonçalves; Erbano, Bruna Olandoski; Mazzaro, Caroline Cantalejo; Klostermann, Flávia Caroline; Sucharski, Enéas Eduardo; Kubrusly, Luiz Fernando

    2014-01-01

    Objective The aim of the present investigation was to determine whether the difference in inflammatory tissue reaction between the Riccinus communis (castor) polymer with calcium carbonate and the titanium implant is statistically significant. Methods Thirty-two Cavia porcellus were allocated into four groups of eight animals each. We implanted the two types of materials in the retroperitoneal space of all the animals. They were euthanized at 7, 20, 30 and 40 days after surgery, and an histological study of the samples was conducted. Results All implants showed characteristics of chronic inflammation regardless of the material and timepoint of evaluation. There was no statistically significant difference between Pm+CaCO3 and Ti with regard to the presence of granulation tissue, tissue congestion, histiocytes, lymphocytes, neutrophils, giant cells, and fibrosis (P> 0.05). Conclusion The castor oil polymer plus calcium carbonate implant was not statistically different from the titanium implant regarding inflammatory tissue reaction. PMID:25140479

  2. Comparative antioxidant status in freshwater fish Carassius auratus exposed to six current-use brominated flame retardants: a combined experimental and theoretical study.

    PubMed

    Feng, Mingbao; Qu, Ruijuan; Wang, Chao; Wang, Liansheng; Wang, Zunyao

    2013-09-15

    Decabromodiphenyl ether (BDE-209) and several non-polybrominated diphenyl ether (PBDE) brominated flame retardants (BFRs), such as tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), decabromodiphenyl ethane (DBDPE), hexabromobenzene (HBB) and pentabromotoluene (PBT), are persistent halogenated contaminants ubiquitously detected in aquatic systems. However, data on comparative toxicological effects of these BFRs are lacking for fish. In this study, a combined experimental and theoretical approach was used to compare and analyze the effects of these BFRs on biochemical biomarkers in liver of Carassius auratus injected intraperitoneally with different doses (10 and 100mg/kg) for 7, 14 and 30 days. Oxidative stress was evoked evidently for the prolonged exposure, represented by the significantly altered indices (superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, and malondialdehyde). The integrated biomarker response (IBR) index ranked biotoxicity as: PBT>HBB>HBCD>TBBPA>BDE-209>DBDPE. Quantum chemical calculations (electronic parameters, frontier molecular orbitals, and Wiberg bond order) were performed for theoretical analysis. Notably, some descriptors were correlated with the toxicity order, probably implying the existence of a potential structure-activity relationship when more BFRs were included. Besides, theoretical calculations also provided some valuable information regarding the molecular characteristics and metabolic pathways of these current-use BFRs, which may facilitate the understanding on their environmental behavior and fate. Overall, this study adopted a combined experimental and theoretical method for the toxicological determination and analysis of the BFRs, which may also be considered in future ecotoxicological studies. PMID:23880106

  3. A Novel Foam Contrast Agent Suitable for Fluoroscopic Interventional Procedure: Comparative Study of Physical Properties and Experimental Intervention in Animal Model

    PubMed Central

    Hwang, Jin Ho; Park, Hong Suk; Seo, Soowon; Choo, In Wook; Do, Young Soo; Choo, Sung Wook; Shin, Sung Wook; Park, Kwang Bo; Cho, Sung Ki; Hyun, Dongho; Lim, Sooyoun

    2015-01-01

    In fluoroscopic contrast study for interventional procedure, liquid contrast agent may be diluted in body fluid, losing its contrast effect. We developed a novel contrast agent of “foam state” to maintain contrast effect for enough time and performed a comparative study of physical properties and its usefulness in experimental intervention in animal model. The mean size of microbubble of foam contrast was 13.8 ± 3.6 µm. The viscosity was 201.0 ± 0.624 cP (centipoise) and the specific gravity was 0.616. The foam decayed slowly and it had 97.5 minutes of half-life. In terms of the sustainability in a slow flow environment, foam contrast washed out much more slowly than a conventional contrast. In experimental colonic stent placement, foam contrast revealed significantly better results than conventional contrast in procedure time, total amount of contrast usage, and the number of injections (p < 0.05). Our foam contrast has high viscosity and low specific gravity and maintains foam state for a sufficient time. Foam contrast with these properties was useful in experimental intervention in animal model. We anticipate that foam contrast may be applied to various kinds of interventional procedures. PMID:26366422

  4. A comparative study on the hepatoprotective action of bear bile and coptidis rhizoma aqueous extract on experimental liver fibrosis in rats

    PubMed Central

    2012-01-01

    Aim of the study Bear bile and Coptidis Rhizoma have been used in Chinese medicine with a long tradition in treating heat-diseases. Both bear bile and Coptidis Rhizoma are used to treat liver diseases in clinical practice of Chinese Medicine. Since bears are currently endangered, it raises the question whether the use of bear bile is ethical. To look for substitute for bear bile, the aim of this study is to compare the anti-fibrotic effects of Coptidis Rhizoma and its major component berberine with the actions of bear bile and its major compound tauroursodeoxycholic acid on experimental liver fibrosis in rats. Method Quality assessment was conducted with high performance liquid chromatography. The experimental liver fibrosis in rats was induced by carbon tetrachloride, alcohol, and bile duct ligation respectively. The biochemical criteria in the blood and tissue samples were measured to evaluate the anti-fibrotic properties and underlying mechanisms of the drugs. Results Coptidis Rhizoma Aqueous Extract (CRAE), berberine, and bear bile exerted anti-fibrotic properties on various liver fibrosis models in rats. CRAE and berberine significantly reduced the peroxidative stress in liver through increasing the superoxide dismutase enzyme activity. CRAE and berberine were able to excrete bilirubin products from the liver and protect hepatocytes from cholestatic damage. The effect of CRAE and berberine are comparable to that of bear bile. Conclusion Instead of using bear bile, CRAE and berberine can be potential substitutes in treating liver fibrosis. PMID:23190573

  5. Magnetohydrodynamic generator experimental studies

    NASA Technical Reports Server (NTRS)

    Pierson, E. S.

    1972-01-01

    The results for an experimental study of a one wavelength MHD induction generator operating on a liquid flow are presented. First the design philosophy and the experimental generator design are summarized, including a description of the flow loop and instrumentation. Next a Fourier series method of treating the fact that the magnetic flux density produced by the stator is not a pure traveling sinusoid is described and some results summarized. This approach appears to be of interest after revisions are made, but the initial results are not accurate. Finally, some of the experimental data is summarized for various methods of excitation.

  6. Experimental Study on the Comparative Thermal Performance of a Solar Collector Using Coconut Coir over the Glass-wool Thermal Insulation for Water Heating System

    NASA Astrophysics Data System (ADS)

    Andoh, H. Y.; Gbaha, P.; Koffi, P. M. E.; Toure, S.; Ado, G.

    This study presents the comparative results of experimental investigations of the thermal performance of two solar water heaters. These technological devices operate under thermosiphon conditions. The first uses the coconut coir, a local vegetable fiber, cheap and available and the second, the glass wool, an imported and expensive material, as thermal insulations. Two complete collectors test facilities, operating in the same conditions, equipped with a data acquisition system, have been assembled and tested for comparing their thermal performances. These tests are performed under various minimum and maximum daily solar intensities, ranging from 220 to 1000 W mG2, from cloudy to sunny days, with the daily outside temperature ranging between 25 to 40?C. The comparative results show an average efficiency of 64% for the two systems when the water mass flow rate reaches 0.010 kg secG1. The increase in temperature through the absorber of the first collector is higher than 40?C, when it is 50?C for the second one. The outlet hot water temperature of the first one reaches 80?C and more, when it is 90?C for the second one. The results show that the first system is quite suitable for application elsewhere and particularly in Africa, at an acquisition cost of 25% cheaper than the traditional one, where there is a plentiful supply of coconut coir.

  7. A comparative experimental and numerical study to investigate the relative merits of convectors and ``C'' inserts in cooling cold-rolled coils

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Tathagata; Chakraborty, Debadi; Singh, Vikas

    2006-12-01

    The coil cooling and storage unit (CCSU) is used to cool cold-rolled coils to the temper rolling temperature after the annealing cycle is over at the batch annealing furnace (BAF) in a cold rolling mill (CRM). In the CCSU, the coils are kept on the cooling bases for any fixed time irrespective of the grade and tonnage. Therefore, the need for a mathematical model to accurately predict the cooling time of the coils was felt. The current study involves experimental and numerical analysis of a stack of coils with respect to heat transfer and fluid flow. A comparative study was carried out to ascertain the relative merits of convectors and “C” inserts (CIs) in the cooling the coils. The air flow distribution for the case of different convectors and CIs was measured by means of a full scale physical model. Two different mathematical models were applied to model the fluid flow and flow distribution through the stack of coils. The first flow model uses the hydraulic resistance concept for estimating the air flow rate distribution, whereas the second flow model uses commercial computational fluid dynamics (CFD) software and predicts the velocity distribution in the flow path between two coils in a stack. The predictions from these two models compare well with the experimental data. The flow models were used to calculate the average heat-transfer coefficient in different flow passages in a stack. The heat-transfer coefficients thus obtained were used to tune and validate a two-dimensional transient heat-transfer model of coils. The heat-transfer model predicts the cooling time of coils accurately and also suggests a possible reduction of cooling time if CIs are used in place of convectors.

  8. Comparing simulated and experimental molecular cluster distributions.

    PubMed

    Olenius, Tinja; Schobesberger, Siegfried; Kupiainen-Määttä, Oona; Franchin, Alessandro; Junninen, Heikki; Ortega, Ismael K; Kurtén, Theo; Loukonen, Ville; Worsnop, Douglas R; Kulmala, Markku; Vehkamäki, Hanna

    2013-01-01

    Formation of secondary atmospheric aerosol particles starts with gas phase molecules forming small molecular clusters. High-resolution mass spectrometry enables the detection and chemical characterization of electrically charged clusters from the molecular scale upward, whereas the experimental detection of electrically neutral clusters, especially as a chemical composition measurement, down to 1 nm in diameter and beyond still remains challenging. In this work we simulated a set of both electrically neutral and charged small molecular clusters, consisting of sulfuric acid and ammonia molecules, with a dynamic collision and evaporation model. Collision frequencies between the clusters were calculated according to classical kinetics, and evaporation rates were derived from first principles quantum chemical calculations with no fitting parameters. We found a good agreement between the modeled steady-state concentrations of negative cluster ions and experimental results measured with the state-of-the-art Atmospheric Pressure interface Time-Of-Flight mass spectrometer (APi-TOF) in the CLOUD chamber experiments at CERN. The model can be used to interpret experimental results and give information on neutral clusters that cannot be directly measured. PMID:24600997

  9. Epoetin Alpha and Epoetin Zeta: A Comparative Study on Stimulation of Angiogenesis and Wound Repair in an Experimental Model of Burn Injury

    PubMed Central

    Irrera, Natasha; Bitto, Alessandra; Pizzino, Gabriele; Vaccaro, Mario; Squadrito, Francesco; Galeano, Mariarosaria; Stagno d'Alcontres, Francesco; Stagno d'Alcontres, Ferdinando; Buemi, Michele; Minutoli, Letteria; Colonna, Michele Rosario; Altavilla, Domenica

    2015-01-01

    Deep second-degree burns are characterized by delayed formation of granulation tissue and impaired angiogenesis. Erythropoietin (EPO) is able to stimulate angiogenesis and mitosis, activating vascularization and cell cycle. The aim of our study was to investigate whether two biosimilar recombinant human erythropoietins, EPO-α and EPO-Z, may promote these processes in an experimental model of burn injury. A total of 84 mice were used and a scald burn was produced on the back after shaving, in 80°C water for 10 seconds. Mice were then randomized to receive EPO-α (400 units/kg/day/sc) or EPO-Z (400 units/kg/day/sc) or their vehicle (100 μL/day/sc 0.9% NaCl solution). After 12 days, both EPO-α and EPO-Z increased VEGF protein expression. EPO-α caused an increased cyclin D1/CDK6 and cyclin E/CDK2 expression compared with vehicle and EPO-Z (p<0.001). Our study showed that EPO-α and EPO-Z accelerated wound closure and angiogenesis; however EPO-α resulted more effectively in achieving complete skin regeneration. Our data suggest that EPO-α and EPO-Z are not biosimilars for the wound healing effects. The higher efficacy of EPO-α might be likely due to its different conformational structure leading to a more efficient cell proliferation and skin remodelling. PMID:26146639

  10. Unreamed or RIA reamed nailing: an experimental sheep study using comparative histological assessment of affected bone tissue in an acute fracture model.

    PubMed

    Klein, Christian; Sprecher, Christoph; Rahn, Berton A; Green, James; Müller, Christof A

    2010-11-01

    The purpose of the present study was to evaluate the Reamer/Irrigator/Aspirator (RIA), a reaming system designed to incorporate the advantages of irrigation and suction for every day clinical use. The evaluation process was focused on the displacement of the medullary content and its impact on cortical perfusion. The results of the RIA reamed nailing were compared to conventional non-reamed nailing (NRN). The tibia of the sheep was used as an acute fracture model. The fracture and nailing procedure was followed by intravital staining with Procion red. The effects on cortical perfusion (Procion red staining) were addressed in polymer embedded sections and cryosections. Sudan III stained cryosections were evaluated with respect to the cortical fat distribution. After irrigation and suction minute amounts of fat were observed in the cortex, whereas after non-reamed nailing the endosteal third of the cortical bone was penetrated with fat. Non-reamed nailing acutely showed better perfusion in the endosteal tenth and periosteal third of the cortical bone, after irrigation and suction reaming perfusion was preserved to a lesser degree. Irrigation and suction significantly reduces fat intravasation, and thus the danger of system-wide damage. Therefore, the Reamer/Irrigator/Aspirator is as efficient as its experimental predecessors. PMID:21144924

  11. Operations dashboard: comparative study

    NASA Astrophysics Data System (ADS)

    Ramly, Noor Nashriq; Ismail, Ahmad Zuhairi; Aziz, Mohd Haris; Ahmad, Nurul Haszeli

    2011-10-01

    In this present days and age, there are increasing needs for companies to monitor application and infrastructure health. Apart from having proactive measures to secure their application and infrastructure, many see monitoring dashboards as crucial investment in disaster preparedness. As companies struggle to find the best solution to cater for their needs and interest for monitoring their application and infrastructure's health, this paper summarizes the studies made on several known off-the-shelf operations dashboard and in-house developed dashboard. A few criteria of good dashboard are collected from previous studies carried out by several researchers and rank them according to importance and business needs. The finalized criteria that will be discussed in later sections are data visualization, performance indicator, dashboard personalization, audit capability and alert/ notification. Comparative studies between several popular dashboards were then carried out to determine whether they met these criteria that we derived from the first exercise. The findings hopefully can be used to educate and provide an overview of selecting the best IT application and infrastructure operations dashboard that suit business needs, thus become the main contribution of this paper.

  12. Use of Mometasone furoate in prolonged treatment of experimental spinal cord injury in mice: A comparative study of three different glucocorticoids.

    PubMed

    Galuppo, Maria; Rossi, Antonietta; Giacoppo, Sabrina; Pace, Simona; Bramanti, Placido; Sautebin, Lidia; Mazzon, Emanuela

    2015-09-01

    Traumatic spinal cord injury (SCI) represents one of the most disabling injuries of the human body causing temporary or permanent sensory and/or motor system deficit, particularly hind limb locomotor function impairment. At present, steroidal inflammatory drugs, in particular methylprednisolone sodium succinate (MPSS) are the first line choice treatment of acute SCI. Despite progress in pharmacological, surgical and rehabilitative treatment approaches, SCI still remains a very complex medical and psychological challenge, with no curative therapy available. The aim of the present study was to compare the efficacy of MPSS in respect to other GCs such as dexamethasone (Dex) and mometasone furoate (MF) in an in vitro suitable model of LPS-induced inflammation in J774 cells as well as in an in vivo experimental mouse SCI (compression model). In both the in vitro and in vivo experiments, MF resulted surprisingly more potent than Dex and MPSS. In detail, mice sacrificed seven days after induction of SCI trauma resulted not only in tissue damage, cellular infiltration, fibrosis, astrocyte activation, iNOS expression, extracellular signal regulated kinase 1/2 phosphorylation in injured tissue, poly (ADP-ribose) polymerase 1 (PARP-1) activation but also apoptosis (Bax and Bcl-2 expression). All three GCs demonstrated the ability to modulate inflammatory, oxidative as well as apoptotic pathways, but MF demonstrated the best efficacy, while Dex and MPSS showed alternative potency with a different degree of protection. Therefore, we can conclude that MF is the best candidate for post-traumatic chronic treatment, since it ameliorates different molecular pathways involved in the damage's propagation to the surrounding areas of the injured spinal cord. PMID:26192346

  13. Linezolid compared with vancomycin for the prevention of methicillin-resistant Staphylococcus aureus or Staphylococcus epidermidis vascular graft infection in rats: A randomized, controlled, experimental study

    PubMed Central

    Sacar, Suzan; Sacar, Mustafa; Kaleli, Ilknur; Toprak, Semra; Cevahir, Nural; Teke, Zafer; Asan, Ali; Sahin, Barbaros; Baltalarli, Ahmet; Turgut, Huseyin

    2007-01-01

    Background: Graft infections are severe complications of vascular surgery that may result in amputation or mortality. Staphylococci are the most frequent cause of vascular graft infections. Objective: In this study we assessed the prophylactic efficacy of linezolid in comparison with vancomycin in preventing prosthetic vascular graft infection due to methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-resistant Staphylococcus epidermidis (MRSE). Methods: This randomized, controlled, experimental study using healthy adult (aged >5 months) male Wistar rats was conducted in the research laboratory of the Pamukkale University, Denizli, Turkey. The study consisted of an uncontaminated control group and 3 groups for both staphylococcal strains: a contaminated group that did not receive any antibiotic prophylaxis; a contaminated group that received preoperative intraperitoneal (IP) prophylaxis with vancomycin; and a contaminated group that received preoperative IP prophylaxis with linezolid. All rats received a vascular Dacron graft placed inside a subcutaneous pocket created on the right side of the median line. Sterile saline solution (1 mL), to which MRSA or MRSE at a concentration of 2 × 107 colony-forming units per milliliter had been added, was inoculated onto the graft surface using a tuberculin syringe to fill the pocket. The grafts were explanted 7 days after implantation and assessed by quantitative culture. Results: Seventy rats (mean [SD]weight, 323.7 [17.9]g; mean [SD]age, 5.98 [0.64] months) were evenly divided between the 7 groups. Statistical analysis of the quantitative graft culture suggested that both vancomycin and linezolid were effective in significantly inhibiting bacterial growth when compared with the untreated contaminated groups (all, P < 0.001). However, a statistically significant difference was not observed between the bacteria count in the vancomycin and linezolid prophylaxis groups. When a comparison was made between the

  14. Comparative study of the corrosion behavior of peripheral stents in an accelerated corrosion model: experimental in vitro study of 28 metallic vascular endoprostheses

    PubMed Central

    Paprottka, Karolin J.; Paprottka, Philipp M.; Reiser, Maximilian F.; Waggershauser, Tobias

    2015-01-01

    PURPOSE Clinical cases of stent-fractures show that corrosion behavior might play a role in these fractures. Implanted in vivo, especially in combination with other implanted foreign materials, these metallic products are exposed to special conditions, which can cause a process of corrosion. Here, we aimed to test the corrosion potential of stents made of different materials in an in vitro setting. METHODS A total of 28 peripheral stents of different materials (nitinol, cobalt-chromium-nickel, tantalum, V4A) and surface treatments (electropolish, mechanical polish, no polish) were tested in vitro. Corrosion was accelerated by applying a constant voltage of 3.5 V and amperage of 1.16 mA in 0.9% NaCl. RESULTS Nitinol stents showed the lowest susceptibility to corrosion and the longest period without damage. The Memotherm II® (BARD Angiomed®) was the only stent that showed neither macroscopic nor microscopic damages. The worst performing material was cobalt-chromium-nickel, which showed corrosion damages about ten times earlier compared to nitinol. Considering the reasons for termination of the test, nitinol stents primarily showed length deficits, while V4A and tantalum stents showed fractures. Cobalt-chromium-nickel stents had multiple fractures or a complete lysis in equal proportions. When placed in direct contact, nitinol stents showed best corrosion resistance, regardless of what material they were combined with. In terms of polishing treatments, electropolished stents performed the best, mechanical-polished stents and those without polishing treatment followed. CONCLUSION The analysis of corrosion behavior may be useful to select the right stent fulfilling the individual needs of the patient within a large number of different stents. PMID:26268301

  15. Mercury methylation, export and bioaccumulation in rice agriculture - model results from comparative and experimental studies in 3 regions of the California Delta, USA

    NASA Astrophysics Data System (ADS)

    Windham-Myers, L.; Fleck, J.; Eagles-Smith, C.; Ackerman, J.

    2013-12-01

    Seasonally flooded wetland ecosystems are often poised for mercury (Hg) methylation, thus becoming sources of methylmercury (MeHg) to in situ and downstream biota. The seasonal flooding associated with cultivation of rice (Oryza sativa) also generates MeHg, which may be stored in sediment or plants, bioaccumulated into fauna, degraded or exported, depending on hydrologic and seasonal conditions. While many U.S. waters are regulated for total Hg concentrations based on fish targets, California's Sacramento-San Joaquin Delta (Delta) will soon implement the first MeHg total maximum daily load (TMDL) control program. Since 2007, a conceptual model (DRERIP-MCM) and several ecosystem-level studies have been advanced to better understand the mechanisms behind Hg methylation, export and bioaccumulation within Delta wetlands, including rice agriculture. Three Delta rice-growing regions (Yolo Bypass, Cosumnes River, Central Delta) of varied soil characteristics, mining influences and hydrology, were monitored over full crop years to evaluate annual MeHg dynamics. In addition to fish tissue Hg accumulation, a broad suite of biogeochemical and hydrologic indices were assessed and compared between wetland types, seasons, and regions. In general, Delta rice fields were found to export MeHg during the post-harvest winter season, and promote MeHg uptake in fish and rice grain during the summer growing season. As described in a companion presentation (Eagles-Smith et al., this session), the experimental Cosumnes River study suggests that rice-derived dissolved organic carbon (DOC) fuels MeHg production and uptake into aquatic foodwebs. Explicit DRERIP-MCM linkages for the role of rice-DOC in MeHg production, export and bioaccumulation were verified across two summers (2011, 2012): rice biomass and root productivity influenced porewater DOC availability and microbial processes, which drove sediment MeHg production and flux to surface water, promoting MeHg bioaccumulation in fish

  16. Experimental study of vortex diffusers

    SciTech Connect

    Shakerin, S.; Miller, P.L.

    1995-11-01

    This report documents experimental research performed on vortex diffusers used in ventilation and air-conditioning systems. The main objectives of the research were (1) to study the flow characteristics of isothermal jets issuing from vortex diffusers, (2) to compare the vortex diffuser`s performance with that of a conventional diffuser, and (3) to prepare a report that disseminates the results to the designers of ventilation and air-conditioning systems. The researchers considered three diffusers: a conventional round ceiling diffuser and two different styles of vortex diffusers. Overall, the vortex diffusers create slightly more induction of ambient air in comparison to the conventional diffuser.

  17. Comparative Packaging Study

    NASA Technical Reports Server (NTRS)

    Perchonok, Michele H.; Oziomek, Thomas V.

    2009-01-01

    Future long duration manned space flights beyond low earth orbit will require the food system to remain safe, acceptable and nutritious. Development of high barrier food packaging will enable this requirement by preventing the ingress and egress of gases and moisture. New high barrier food packaging materials have been identified through a trade study. Practical application of this packaging material within a shelf life test will allow for better determination of whether this material will allow the food system to meet given requirements after the package has undergone processing. The reason to conduct shelf life testing, using a variety of packaging materials, stems from the need to preserve food used for mission durations of several years. Chemical reactions that take place during longer durations may decrease food quality to a point where crew physical or psychological well-being is compromised. This can result in a reduction or loss of mission success. The rate of chemical reactions, including oxidative rancidity and staling, can be controlled by limiting the reactants, reducing the amount of energy available to drive the reaction, and minimizing the amount of water available. Water not only acts as a media for microbial growth, but also as a reactant and means by which two reactants may come into contact with each other. The objective of this study is to evaluate three packaging materials for potential use in long duration space exploration missions.

  18. Topical use of Rectogesic® and Emla® to improve cutaneous blood perfusion following thermal injury. A comparative experimental study.

    PubMed

    Tagkalakis, P; Dionyssopoulos, A; Karkavelas, G; Demiri, E

    2015-06-30

    Early post-burn ischemic necrosis of the skin is of particular interest in modern burn research. The purpose of this study was to test the hypothesis that blood perfusion could be improved by the topical application of vasoactive substances. A sample of 55 wistar rats was used to investigate the effect of 0,4% nitroglycerin ointment (Rectogesic(®)) comparatively to no application and placebo. The beneficiary action of 5% prilocaine/lidocaine cream (EMLA(®)) in burn blood perfusion was also tested comparatively to Rectogesic(®). Both preparations were tested respectively to non burned controls. Laser Doppler assessment of blood flow at 15, 30, 45, 60, 120 and 180 minutes after preparation application, demonstrated that the use of Rectogesic(®) improved perfusion at all measurements compared to placebo and to no preparation application (p&0,05). There was no statistical significant difference in the effect of the two preparations. PMID:27252612

  19. Topical use of Rectogesic® and Emla® to improve cutaneous blood perfusion following thermal injury. A comparative experimental study

    PubMed Central

    Tagkalakis, P.; Dionyssopoulos, A.; Karkavelas, G.; Demiri, E.

    2015-01-01

    Summary Early post-burn ischemic necrosis of the skin is of particular interest in modern burn research. The purpose of this study was to test the hypothesis that blood perfusion could be improved by the topical application of vasoactive substances. A sample of 55 wistar rats was used to investigate the effect of 0,4% nitroglycerin ointment (Rectogesic®) comparatively to no application and placebo. The beneficiary action of 5% prilocaine/lidocaine cream (EMLA®) in burn blood perfusion was also tested comparatively to Rectogesic®. Both preparations were tested respectively to non burned controls. Laser Doppler assessment of blood flow at 15, 30, 45, 60, 120 and 180 minutes after preparation application, demonstrated that the use of Rectogesic® improved perfusion at all measurements compared to placebo and to no preparation application (p&0,05). There was no statistical significant difference in the effect of the two preparations. PMID:27252612

  20. Cross-Laboratory Comparative Study of the Impact of Experimental and Regression Methodologies on Salmonella Thermal Inactivation Parameters in Ground Beef.

    PubMed

    Hildebrandt, Ian M; Marks, Bradley P; Juneja, Vijay K; Osoria, Marangeli; Hall, Nicole O; Ryser, Elliot T

    2016-07-01

    Isothermal inactivation studies are commonly used to quantify thermal inactivation kinetics of bacteria. Meta-analyses and comparisons utilizing results from multiple sources have revealed large variations in reported thermal resistance parameters for Salmonella, even when in similar food materials. Different laboratory or regression methodologies likely are the source of methodology-specific artifacts influencing the estimated parameters; however, such effects have not been quantified. The objective of this study was to evaluate the effects of laboratory and regression methodologies on thermal inactivation data generation, interpretation, modeling, and inherent error, based on data generated in two independent laboratories. The overall experimental design consisted of a cross-laboratory comparison using two independent laboratories (Michigan State University and U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center [ERRC] laboratories), both conducting isothermal Salmonella inactivation studies (55, 60, 62°C) in ground beef, and each using two methodologies reported in prior studies. Two primary models (log-linear and Weibull) with one secondary model (Bigelow) were fitted to the resultant data using three regression methodologies (two two-step regressions and a one-step regression). Results indicated that laboratory methodology impacted the estimated D60°C- and z-values (α = 0.05), with the ERRC methodology yielding parameter estimates ∼25% larger than the Michigan State University methodology, regardless of the laboratory. Regression methodology also impacted the model and parameter error estimates. Two-step regressions yielded root mean square error values on average 40% larger than the one-step regressions. The Akaike Information Criterion indicated the Weibull as the more correct model in most cases; however, caution should be used to confirm model robustness in application to real-world data. Overall, the

  1. Comparing Experimental and Simulated Pressure-Area Isotherms for DPPC

    PubMed Central

    Duncan, Susan L.; Larson, Ronald G.

    2008-01-01

    Although pressure-area isotherms are commonly measured for lipid monolayers, it is not always appreciated how much they can vary depending on experimental factors. Here, we compare experimental and simulated pressure-area isotherms for dipalmitoylphosphatidylcholine (DPPC) at temperatures ranging between 293.15 K and 323.15 K, and explore possible factors influencing the shape and position of the isotherms. Molecular dynamics simulations of DPPC monolayers using both coarse-grained (CG) and atomistic models yield results that are in rough agreement with some of the experimental isotherms, but with a steeper slope in the liquid-condensed region than seen experimentally and shifted to larger areas. The CG lipid model gives predictions that are very close to those of atomistic simulations, while greatly improving computational efficiency. There is much more variation among experimental isotherms than between isotherms obtained from CG simulations and from the most refined simulation available. Both atomistic and CG simulations yield liquid-condensed and liquid-expanded phase area compressibility moduli that are significantly larger than those typically measured experimentally, but compare well with some experimental values obtained under rapid compression. PMID:18199666

  2. A comparative study of the industrial discharges effect on the anaerobic treatment of domestic wastewater in both experimental and pilot-plant scales.

    PubMed

    Saddoud, Ahlem; Abdelkafi, Slim; Aloui, Fathi; Sayadi, Sami

    2010-11-01

    The aim of this study was to compare the effect of industrial discharges on the anaerobic treatment of domestic wastewater in both laboratory and pilot-plant scales at mesophilic conditions. The laboratory experiment results have shown the low process efficiency of anaerobic treatment of DW by the use of an adapted or a non-adapted methanogenic inoculum. These experiments performed in batch digesters were further confirmed by scaling up to a pilot-plant anaerobic membrane bioreactor (MBR). The treatment inefficiency in both laboratory and pilot-plant experiments could be related to the presence of toxic compounds due to the wastewater contamination by industrial discharges. The toxic character of DW was proved by the phytotoxicity and microtoxicity tests. Indeed, the luminescence inhibition percentages started at an average of 21% in the morning and reached more than 84% in the late afternoon. Moreover, the toxicity results have shown a direct relation with methanization results. Indeed, when the average microtoxicity increased to 73%, the average germination index value and the methanization efficiency expressed as the average methane percentage in the produced biogas decreased to 0% and 14.5%, respectively. PMID:21121456

  3. Comparative Histological Study on the Therapeutic Effect of Green Tea and Stem Cells in Alzheimer’s Disease Complicating Experimentally Induced Diabetes

    PubMed Central

    Bassiony, Hend Shafik; Zickri, Maha Baligh; Metwally, Hala Gabr; Elsherif, Hala Ahmed; Alghandour, Sarah Mohammed; Sakr, Wael

    2015-01-01

    Background and Objectives Alzheimer’s disease (AD) is a devastating neurodegenerative disorder. Increasing evidence implicates diabetes mellitus (DM) as a risk factor for AD. Green tea (GT) has several beneficial effects attributed to its anti-oxidant phenolic compounds. Adipose tissue is a rich source of adipose-derived mesenchymal stem cells (ADSCs). This study was designed to evaluate and compare the possible therapeutic effect of green tea extract (GTE) and ADSCs on AD complicating induced DM in male rat. Methods 31 adult male albino rats were divided into 5 groups. Group I (Control), Group II received GTE, 50 mg/kg daily orally for 4 weeks, Group III received a single intraperitoneal injection of Streptozotocin (STZ), 50 mg/kg, Group IV: received STZ followed by GTE and Group V: received STZ followed by human ADSCs (hADSCs) intravenously. Results Multiple acidophilic masses, deformed neurons, Congo red +ve masses and Caspase 3 +ve neurons were seen in group III, became few in group IV and occasional in group V. Multiple Prussian blue +ve cells were detected in group V. Some CD44 +ve cells were noticed in group III, became multiple in groups IV and V. The mean area of neurons exhibiting acidophilic cytoplasm, mean area of amyloid plaques and mean area % of Caspase 3 +ve cells indicated a significant increase in group III. The mean area % of CD44 +ve cells recorded a significant increase in group IV. Conclusions hADSCs exerted a more marked therapeutic effect on the neurodegenerative changes complicating DM and corresponding to AD. PMID:26634066

  4. Comparative studies of gene regulatory mechanisms.

    PubMed

    Pai, Athma A; Gilad, Yoav

    2014-12-01

    It has become increasingly clear that changes in gene regulation have played an important role in adaptive evolution both between and within species. Over the past five years, comparative studies have moved beyond simple characterizations of differences in gene expression levels within and between species to studying variation in regulatory mechanisms. We still know relatively little about the precise chain of events that lead to most regulatory adaptations, but we have taken significant steps towards understanding the relative importance of changes in different mechanisms of gene regulatory evolution. In this review, we first discuss insights from comparative studies in model organisms, where the available experimental toolkit is extensive. We then focus on a few recent comparative studies in primates, where the limited feasibility of experimental manipulation dictates the approaches that can be used to study gene regulatory evolution. PMID:25215415

  5. Experimental Study Comparing a Traditional Approach to Performance Appraisal Training to a Whole-Brain Training Method at C.B. Fleet Laboratories

    ERIC Educational Resources Information Center

    Selden, Sally; Sherrier, Tom; Wooters, Robert

    2012-01-01

    The purpose of this study is to examine the effects of a new approach to performance appraisal training. Motivated by split-brain theory and existing studies of cognitive information processing and performance appraisals, this exploratory study examined the effects of a whole-brain approach to training managers for implementing performance…

  6. Optimizing experimental design for comparing models of brain function.

    PubMed

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

    2011-11-01

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

  7. Cross-laboratory comparative study of the impact of experimental and regression methodologies on salmonella thermal inactivation parameters in ground beef

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Isothermal inactivation studies are commonly used to quantify thermal inactivation kinetics of bacteria. Meta-analyses and comparisons utilizing results from multiple sources have revealed large variations in reported inactivation parameters for Salmonella, even in similar food materials. Different ...

  8. Self-Efficacy, Planning, or a Combination of Both? A Longitudinal Experimental Study Comparing Effects of Three Interventions on Adolescents’ Body Fat

    PubMed Central

    Luszczynska, Aleksandra; Hagger, Martin S.; Banik, Anna; Horodyska, Karolina; Knoll, Nina; Scholz, Urte

    2016-01-01

    Background The superiority of an intervention combining two sets of theory-based behavior change techniques targeting planning and self-efficacy over an intervention targeting planning only or self-efficacy only has rarely been investigated. Purpose We compared the influence of self-efficacy, planning, and self-efficacy+planning interventions with an education-based control condition on adolescents’ body fat, assuming mediating effects of respective social cognitive variables and moderate-to-vigorous physical activity (MVPA). The moderating role of the built environment was examined. Methods Participants (N = 1217, aged 14–18 years) were randomly assigned to four conditions: planning (n = 270), self-efficacy (n = 311), self-efficacy+planning (n = 351), and control (n = 285). The measurement was conducted at baseline (T1), two-month follow-up (T2), and fourteen-month follow-up (T3). Interventions/control group procedures were delivered at T1 and T2. Percent of body fat tissue (measured at T1 and T3) was the main outcome. Social cognitive mediators (self-efficacy and planning) were assessed at T1 and T2. The behavioral mediator (MVPA) and the presence of built MVPA facilities (the moderator) were evaluated at T1 and T3. Results Similar small increases of body fat were found across the three intervention groups, but the increment of body fat was significantly larger in the control group. On average, differences between control and intervention groups translated to approximately 1% of body fat. Effects of the interventions on body fat were mediated by relevant social cognitive variables and MVPA. A lower increase of body fat was found among intervention group participants who had access to newly-built MVPA facilities. Conclusions We found no superiority of an intervention targeting two social cognitive variables over the intervention targeting one cognition only. PMID:27410961

  9. Effects of captopril, telmisartan and bardoxolone methyl (CDDO-Me) in ischemia-reperfusion-induced acute kidney injury in rats: an experimental comparative study.

    PubMed

    Kocak, Cengiz; Kocak, Fatma Emel; Akcilar, Raziye; Bayat, Zeynep; Aras, Bekir; Metineren, Mehmet Huseyin; Yucel, Mehmet; Simsek, Hasan

    2016-02-01

    Renal ischemia-reperfusion (IR) injury is one of the most common causes of acute kidney injury. This study investigated the effects of captopril (CAP), telmisartan (TEL) and bardoxolone methyl (BM) in animals with renal IR injury. Adult male Wistar-Albino rats were divided into six groups: control, vehicle, IR, IR with CAP, IR with TEL and IR with BM. Before IR was induced, drugs were administered by oral gavage. After a 60-min ischemia and a 120-min reperfusion period, bilateral nephrectomies were performed. Serum urea, creatinine, neutrophil gelatinase-associated lipocalin (NGAL) levels, tissue total oxidant status (TOS), total antioxidant status (TAS), total thiol (TT), asymmetric dimethylarginine (ADMA) levels, superoxide dismutase (SOD) activity and glutathione peroxidase (GSH-Px) activity were measured. Tissue mRNA expression levels of peroxisome proliferator-activated receptor-ɣ (PPAR-ɣ), nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) were analyzed. In addition, renal tissues were evaluated histopathologically and immunohistochemically. All tested drugs reduced renal damage, apoptosis, urea, creatinine, NGAL, TOS, nitric oxide (NO) and ADMA levels, NF-κB, inducible nitric oxide synthase (iNOS) and endothelin-1 (ET-1) expressions (P < 0.001). All tested drugs increased SOD activity, GSH-Px activity, TAS levels, TT levels, endothelial nitric oxide synthase (eNOS) expression, dimethylarginine dimethylaminohydrolases (DDAHs) expression, Nrf2 expression and PPAR-ɣ expression (P < 0.001, P < 0.003). These results suggest that CAP, TEL and BM pretreatment could reduce renal IR injury via anti-inflammatory, antioxidant and anti-apoptotic effects. PMID:26515498

  10. Experimental Studies in Ice Nucleation

    NASA Astrophysics Data System (ADS)

    Wright, Timothy Peter

    Ice nuclei play a critical role in the formation of precipitation in mixed phase clouds. Modification of IN concentrations can lead to changes in cloud lifetimes and precipitation size. Presented in this study are experimental investigations into ice nuclei in an ongoing effort to reduce the uncertainties that ice nuclei have on cloud processes and climate. This research presents a new version of the cold stage drop freezing assay to investigate the time-dependence of heterogeneous nucleation. The temperature range for the instrument spans from the melting point of water to the homogeneous freezing limit of ˜-38 deg C. Temperature stability for the instrument allowed for experimental operation for up to four days while interrogating the same sample. Up to a one hundred fold increase in the number of analyzed drops was accomplished through an in-house written automated drop freezing detection software package. Combined instrument design improvements allow for the analysis of IN concentrations down to ˜10-8 ice nuclei per picoliter of sample water. A new variant of the multiple-component stochastic model for heterogeneous ice nucleation was used to investigate the time dependence of heterogeneous freezing processes. This was accomplished by analyzing how the changes in the cooling rate can impact the observed nucleation rate. The model employed four material-dependent parameters to accurately capture the observed freezing of water drops containing Arizona Test Dust. The parameters were then used to accurately predict the freezing behavior of the drops in time dependent experiments. The time dependence freezing of a wide range of materials was then investigated. These materials included the minerals montmorillonite and kaolinite, the biological proxy ice nuclei contained within the product Icemax, and flame soot generated from the incomplete combustion of ethylene gas. The time dependence for ice nuclei collected from rainwater samples was also investigated. The

  11. Experimental study in order to assess the effects of limited periosteum stripping on the fracture healing and to compare osteosynthesis using plates and screws with intramedullary Kirschner wire fixation.

    PubMed

    Neagu, Tiberiu Paul; Enache, Valentin; Cocoloş, Ion; Ţigliş, Mirela; Cobilinschi, Cristian; Ţincu, Radu

    2016-01-01

    There are many studies that investigate indirect and direct fracture healing but few mention the effect of periosteum stripping on consolidation of fractures. Most of these studies use only one method of osteosynthesis for each group. Therefore, we reported a new developed murine model in order to assess if limited periosteum stripping influence significantly the quality of the fracture healing process by comparing two different osteosynthesis methods to reduce simultaneously bilateral femur fractures. We applied the experimental protocol for a number of 12 rats. We used plates and screws to reduce femoral osteotomy for the right hind limb and intramedullary Kirschner wire for the left hind limb. Clinical, radiological and histological assessments were made for a period of eight weeks. The absence of a healthy hind limb led to a slower healing process based on the histological findings and to implant failure based on radiological findings. In summary, complete fracture healing was not achieved during this experimental study. Therefore, we consider that future studies are needed for a better understanding of the effects of periosteum removal on the fracture healing process. PMID:27516016

  12. The Utility of Geographical Information Systems (GIS) in Systems-Oriented Obesity Intervention Projects: The Selection of Comparable Study Sites for a Quasi-Experimental Intervention Design—TX CORD

    PubMed Central

    Byars, Allison; Byrd-Williams, Courtney; Sharma, Shreela V.; Durand, Casey; Hoelscher, Deanna M.; Butte, Nancy F.; Kelder, Steven H.

    2015-01-01

    Abstract Background: The Texas Childhood Obesity Research Demonstration project (TX CORD) uses a systems-oriented approach to address obesity that includes individual and family interventions, community-level action, as well as environmental and policy initiatives. Given that randomization is seldom possible in community-level intervention studies, TX CORD uses a quasi-experimental design. Comparable intervention and comparison study sites are needed to address internal validity bias. Methods: TX CORD was designed to be implemented in low-income, ethnically diverse communities in Austin and Houston, Texas. A three-stage Geographical Information System (GIS) methodology was used to establish and ascertain the comparability of the intervention and comparison study sites. Census tract (stage 1) and school (stage 2) data were used to identify spatially exclusive geographic areas that were comparable. In stage 3, study sites were compared on demographic characteristics, socioeconomic status (SES), food assets, and physical activity (PA) assets. Student's t-test was used to examine significant differences between the selected sites. Results: The methodology that was used resulted in the selection of catchment areas with demographic and socioeconomic characteristics that fit the target population: ethnically diverse population; lower-median household income; and lower home ownership rates. Additionally, the intervention and comparison sites were statistically comparable on demographic and SES variables, as well as food assets and PA assets. Conclusions: This GIS approach can provide researchers, program evaluators, and policy makers with useful tools for both research and practice. Area-level information that allows for robust understanding of communities can enhance analytical procedures in community health research and offer significant contributions in terms of community assessment and engagement. PMID:25587670

  13. Arbitrarily Applicable Comparative Relations: Experimental Evidence for a Relational Operant

    PubMed Central

    Berens, Nicholas M; Hayes, Steven C

    2007-01-01

    Arbitrarily applicable derived relational responding has been argued by relational frame theorists to be a form of operant behavior. The present study examined this idea with 4 female participants, ages 4 to 5 years old, who could not perform a series of problem-solving tasks involving arbitrary more than and less than relations. In a combined multiple baseline (across responses and participants) and multiple probe design (with trained and untrained stimuli), it was shown that reinforced multiple-exemplar training facilitated the development of arbitrary comparative relations, and that these skills generalized not just across stimuli but also across trial types. The sequence of training identified potential prerequisites in the development of comparative relations (e.g., nonarbitrary comparative relations). Taken as a whole, the present data, along with previous work by others in this area, suggest that relating arbitrary events comparatively is an operant. The implications of this conclusion for the analysis of complex behavior are discussed. PMID:17471793

  14. Union Underground: Political Issues. Comparing Political Experiences, Experimental Edition.

    ERIC Educational Resources Information Center

    Gillespie, Judith A.; Lazarus, Stuart

    This is the third unit to the second-semester "Comparing Political Experiences" course which focuses on a specific, controversial, political issue. The unit analyzes the concept of political maintenance by studying the United Mine Workers of America (UMWA) between 1918 and 1975 and its fight to secure mine safety standards. A documentary approach…

  15. Comparing simulated emission from molecular clouds using experimental design

    SciTech Connect

    Yeremi, Miayan; Flynn, Mallory; Loeppky, Jason; Rosolowsky, Erik; Offner, Stella

    2014-03-10

    We propose a new approach to comparing simulated observations that enables us to determine the significance of the underlying physical effects. We utilize the methodology of experimental design, a subfield of statistical analysis, to establish a framework for comparing simulated position-position-velocity data cubes to each other. We propose three similarity metrics based on methods described in the literature: principal component analysis, the spectral correlation function, and the Cramer multi-variate two-sample similarity statistic. Using these metrics, we intercompare a suite of mock observational data of molecular clouds generated from magnetohydrodynamic simulations with varying physical conditions. Using this framework, we show that all three metrics are sensitive to changing Mach number and temperature in the simulation sets, but cannot detect changes in magnetic field strength and initial velocity spectrum. We highlight the shortcomings of one-factor-at-a-time designs commonly used in astrophysics and propose fractional factorial designs as a means to rigorously examine the effects of changing physical properties while minimizing the investment of computational resources.

  16. Experimental studies of glass refining

    NASA Technical Reports Server (NTRS)

    Subramanian, R. S.; Cole, R.; Kondos, P.

    1984-01-01

    The basic components of the experimental apparatus were selected and acquired. Techniques were developed for the fabrication of the special crucibles necessary for the experiments. Arrangements were made for the analysis of glass and gas bubble samples for composition information. Donations of major equipment were received for this project from Owens, Illinois where a similar study had been conducted a few year ago. Decisions were made regarding the actual glass composition to be used, the gas to be used in the first experiments, and the temperatures at which the experiments should be conducted. A microcomputer was acquired, and work was begun on interfacing the video analyzer to it.

  17. Andragogical and Pedagogical Methods Compared: A Review of the Experimental Literature.

    ERIC Educational Resources Information Center

    Rachal, John R.

    Although andragogy became an article of faith among many adult educators in the 25 years since Knowles first popularized the concept, relatively few studies have attempted to compare andragogy and pedagogy experimentally. Eighteen studies that attempted to do so included 15 dissertations and 3 journal articles. The studies were organized by…

  18. Experimental studies with palygorskite dusts.

    PubMed

    Wagner, J C; Griffiths, D M; Munday, D E

    1987-11-01

    As the preliminary results of experimental studies on dust from the palygorskite group have led to some confusion a detailed description of the completed investigation is given for clarification. As in other experiments the biological effects have been shown to be associated with the physical characteristics of the fibres in these specimens. Samples of sepiolite and attapulgite from Spain and a single sample of palygorskite from the United Kingdom have been studied. Serious abnormalities were produced only by the palygorskite and one of the attapulgite dusts. The palygorskite is of no commercial interest and the attapulgite was from one small deposit and was used only in the preparation of drilling mud in the exploration of oil deposits. PMID:2961365

  19. A mechanical diode: Comparing numerical and experimental characterizations

    SciTech Connect

    Simmermacher, T.; Segalman, D.; Sagartz, M.

    1997-12-01

    The predictive modeling of vibration of many structural systems is crippled by an inability to predictively model the mechanics of joints. The lack of understanding of joint dynamics is evidenced by the substantial uncertainty of joint compliances in the numerical models and by the complete inability to predict joint damping. The lore is that at low amplitudes, joint mechanics are associated with Coulomb friction and stick-slip phenomena and that at high amplitudes, impact processes result in dissipation as well as shift of energy to other frequencies. Inadequate understanding of the physics precludes reliable predictions. In this introductory work, joint compliance is studied in both a numerical and experimental setting. A simple bolted interface is used as the test article and compliance is measured for the joint in both compression and in tension. This simple interface is shown to exhibit a strong non-linearity near the transition from compression to tension (or vice-versa). Modeling issues pertaining to numerically solving for the compliance are addressed. It is shown that the model predicts the experimental strains and compliance fairly well. It will be seen that the joint behavior is a mechanical analogy to a diode. In compression, the joint is very stiff, acting almost as a rigid link, while in tension the joint is soft, acting as a soft spring. Although there have been many other studies performed on bolted joints, the variety of joint geometries has demonstrated large variations in behavior. This study is an attempt to quantify the behavior of typical joints found in today`s weapon systems.

  20. Sex work: a comparative study.

    PubMed

    McCarthy, Bill; Benoit, Cecilia; Jansson, Mikael

    2014-10-01

    Explanations of adult involvement in sex work typically adopt one of two approaches. One perspective highlights a variety of negative experiences in childhood and adolescence, including physical and sexual abuse, family instability, poverty, associations with "pimps" and other exploiters, homelessness, and drug use. An alternative account recognizes that some of these factors may be involved, but underscores the contribution of more immediate circumstances, such as current economic needs, human capital, and employment opportunities. Prior research offers a limited assessment of these contrasting claims: most studies have focused exclusively on people working in the sex industry and they have not assessed the independent effects of life course variables central to these two perspectives. We add to this literature with an analysis that drew on insights from life course and life-span development theories and considered the contributions of factors from childhood, adolescence, and adulthood. Our comparative approach examined predictors of employment in sex work relative to two other low-income service or care work occupations: food and beverage serving and barbering and hairstyling. Using data from a study of almost 600 workers from two cities, one in Canada and the other in the United States, we found that both immediate circumstances and negative experiences from early life are related to current sex work involvement: childhood poverty, abuse, and family instability were independently associated with adult sex work, as were limited education and employment experience, adult drug use, and marital status. PMID:24671729

  1. Experimental Infrasound Studies in Nevada

    NASA Astrophysics Data System (ADS)

    Herrin, E. T.; Negraru, P. T.; Golden, P.; Williams, A.

    2009-12-01

    An experimental propagation study was carried out in Nevada in June 2009 on Julian days 173-177. During this field experiment we deployed 16 single channel digital infrasound recorders to monitor the munitions disposal activities near Hawthorne, NV. The sensors were deployed in a single line and placed approximately 12 km apart at distances ranging from 2 to 177 km. A four element semi-permanent infrasound array named FNIAR was installed approximately 154 km north of the detonation site in line with the individual temporary recorders. Tropospheric arrivals were observed during all days of the experiment, but during day 176 the observed arrivals had very large amplitudes. A large signal was observed at 58 km from the detonation site with amplitude as large as 4 Pascals, while at 94 km no signal was observed. At FNIAR the amplitude of the tropospheric arrival was 1 Pascal. During this day meteorological data acquired in the propagation path showed a strong jet stream to the north. On day 177 we were not able to identify tropospheric arrivals beyond 34 km, but at stations beyond 152 km we observed stratospheric arrivals. Continuous monitoring of these signals at FNIAR shows that stratospheric arrivals are the most numerous. In a two month period, from 06/15/2009 to 08/15/2009 there were 35 operational days at the Hawthorne disposal facility resulting in 212 explosions with known origin times. Based on the celerity values there were 115 explosions that have only stratospheric arrivals (celerities of 300-275 m/s), 72 explosions with both tropospheric (celerities above 330 m/s) and stratospheric arrivals, 20 explosions that were not detected and five explosions that have only tropospheric arrivals.

  2. A comparative study of the local cytokine response in the lungs of pigs experimentally infected with different PRRSV-1 strains: upregulation of IL-1α in highly pathogenic strain induced lesions.

    PubMed

    Amarilla, Shyrley P; Gómez-Laguna, Jaime; Carrasco, Librado; Rodríguez-Gómez, Irene M; Caridad Y Ocerín, José M; Morgan, Sophie B; Graham, Simon P; Frossard, Jean-Pierre; Drew, Trevor W; Salguero, Francisco J

    2015-04-15

    Porcine reproductive and respiratory syndrome viruses (PRRSV) show high genetic differences both among and within genotypes. Recently, several highly pathogenic PRRSV (HP-PRRSV) strains have been described. This study compares and characterizes the production of cytokines by pulmonary macrophages in pigs experimentally infected with four different PRRSV-1 strains: two low-virulent strains, Lelystad (LV) and a British field strain (215-06); a HP strain (SU1-bel) from Belarus and the attenuated vaccine strain DV (Porcilis(®) PRRS). Animals were clinically monitored and post-mortem examinations were performed at 3, 7 and 35 days post-infection (dpi). Lung samples were processed for histopathological and immunohistochemical studies by using specific antibodies against PRRSV, IL1-α, IL-6, TNF-α, IL-10 and IFN-γ. SU1-bel infected animals presented the highest mean scores for clinical observations, gross and microscopic lesions as well as for PRRSV expression compared with the other infected groups (p≤0.027). These animals displayed the highest expression of IL1-α at 7dpi, together with the highest score for lung pathology, whereas LV, 215-06 and DV inoculated animals only showed a transient enhancement in some of these cytokines. SU1-bel-infected pigs showed a positive correlation between the amount of PRRSV antigen and IL-1α expression (r=0.645, p<0.001). The highest expression of IL-10 was detected in 215-06-infected animals (p≤0.004), with a positive correlation with the numbers of virus-infected cells (r=0.375, p≤0.013). In conclusion, the HP-PRRSV SU1-bel strain replicated more efficiently in the lung of infected animals and induced a higher expression of IL-1α than the other PRRSV-1-infected groups, which may have played a key role in the onset of the clinical signs and interstitial pneumonia. PMID:25739319

  3. Comparative Studies in Special Education.

    ERIC Educational Resources Information Center

    Mazurek, Kas, Ed.; Winzer, Margret A., Ed.

    This text presents 26 case studies which examine special education provisions for children in the world today. The reports focus on the current state of special education in selected nations and major issues and controversies in the field of special education within those nations. Each case study addresses the following themes: (1) prevalence of…

  4. Comparative Studies of Acculturative Stress.

    ERIC Educational Resources Information Center

    Berry, J. W.; And Others

    1987-01-01

    Studies of acculturative stress are reported from Canada. The reduction in health status among people undergoing acculturation has psychological, somatic, and social aspects. The stress varies across types of groups and individual differences. Further study is needed to determine variations across host societies. (VM)

  5. Experimental study of low frequency drift instability

    SciTech Connect

    Ioffe, M.S.; Kanaev, B.I.; Pastukhov, V.P.

    1994-05-01

    Experimental studies of nondissipative low frequency drift instability are reported; the plasma of a long mirror trap with edge casp anchors was investigated. The instability growth was found to take place only in a limited number of operation modes even in the case of all the growth requirements being satisfied. Furthermore, the instability development is rather moderate, and the associated anomalous losses appear to be small compared to the classical Coulomb losses. Possible factors accounting for the {open_quotes}soft{close_quotes} instability evolution are discussed. 13 refs., 6 figs.

  6. Comparative vibrational analysis of 1,2-Dinitro benzene and 1-Fluoro-3-nitro benzene: A combined experimental (FT-IR and FT-Raman) and theoretical study (DFT/B3LYP/B3PW91)

    NASA Astrophysics Data System (ADS)

    Mahadevan, D.; Periandy, S.; Ramalingam, S.

    2011-12-01

    In this work, the comparative analysis is made on the structure and vibrational spectra of 1,2-Dinitro benzene (1,2-DNB) and 1-Fluoro-3-nitro benzene (1-F-3-NB) molecules. The FT-IR and FT-Raman experimental spectra of the molecules have been recorded using Bruker IFS 66 V spectrometer in the range of 4000-100 cm -1. Making use of the recorded data, the complete vibrational assignments are made and analyses of the observed fundamental bands of molecules are carried out. The experimental determinations of vibrational frequencies are compared with those obtained theoretically from ab-initio Hartree-fock (HF) and DFT (B3LYP and B3PW91) methods with 6-31++G (d, p) and 6-311++G (d, p) basis sets. The differences between the observed and scaled wave number values of most of the fundamentals of the molecules are very small in B3LYP than HF. The geometries and normal modes of vibrations obtained from ab-initio HF and B3LYP/B3PW91 calculations are compared with the experimentally observed data. Comparison of the simulated spectra of the molecules provides important information regarding the difference and similarity of the vibrational characteristics between the molecules. The impact of substitutions on the structures between the molecules is also investigated.

  7. Experimentation in organ transplants compared with clinical trials: ethical problems.

    PubMed

    Petrini, C

    2013-01-01

    The origins of new techniques in transplant surgery vary widely. Frequently, new procedures are the result of small step-by-step departures from protocols already established in clinical practice; or they may be the result of radical innovation. Whatever their origin, experimental techniques in transplant surgery do not follow the route of randomised clinical trials; nor are they subject to the same procedures of review by an ethics committee. The present paper discusses some of the ethical implications of this situation. PMID:24045525

  8. A comparative study of the regenerative effect of sinus bone grafting with platelet-rich fibrin-mixed Bio-Oss® and commercial fibrin-mixed Bio-Oss®: an experimental study.

    PubMed

    Xuan, Feng; Lee, Chun-Ui; Son, Jeong-Seog; Jeong, Seung-Mi; Choi, Byung-Ho

    2014-06-01

    Anorganic bovine bone (Bio-Oss®) particles are one of the most popular grafting materials. The particles are often mixed with platelet-rich fibrin (PRF) or a commercial fibrin (Tisseel®) to form a mouldable graft material. The objective of this study was to compare the potentials of PRF-mixed Bio-Oss® and Tisseel®-mixed Bio-Oss® to enhance bone regeneration in a canine sinus model. Six mongrel dogs were used in this study. After elevating the sinus membrane in both maxillary sinus cavities, an implant was placed into the sinus cavity. In one of the sinus cavities, the PRF/Bio-Oss® composite was grafted, and the Tisseel®/Bio-Oss® composite was grafted in the other sinus cavity. After a 6 month healing period, bone formation in the graft sites and bone-implant contact were evaluated. The mean osseointegration rate was 43.5 ± 12.4% and new bone formation rate 41.8 ± 5.9% in the PRF/Bio-Oss® composite sites. In the Tisseel®/Bio-Oss® composite sites they were 30.7 ± 7.9% and 31.3 ± 6.4%. There were statistically significant differences between the groups. The findings from this study suggest that when platelet-rich fibrin is used as an adjunct to Bio-Oss® particles for bone augmentation in the maxillary sinus, bone formation in the graft sites is significantly greater than when Tisseel® is used. PMID:23911120

  9. [Brackets and friction in orthodontics: experimental study].

    PubMed

    Ben Rejeb Jdir, Saloua; Tobji, Samir; Turki, Wiem; Dallel, Ines; Khedher, Nedra; Ben Amor, Adel

    2015-09-01

    Many authors have been involved in developing brackets in order to improve the quality, stability, speed and efficiency of orthodontic treatment. In order to reduce friction between bracket and archwire, new therapeutic approaches have been devised based on novel technologies. Among these innovative techniques, self-ligating brackets are increasingly popular. SLBs can be classified into several categories according to their mode of action and their materials. We performed an experimental study to compare the friction forces generated during the sliding of orthodontic archwires made from various alloys through conventional and self-ligating brackets. Results show the favorable influence of SLBs, compared to conventional systems using elastomeric or metal ligatures, on the level of friction, particularly when shape-memory Ni-Ti archwires are used. PMID:26370596

  10. Busing in Boston: Political Issues. Comparing Political Experiences, Experimental Edition.

    ERIC Educational Resources Information Center

    Gillespie, Judith A.; Lazarus, Stuart

    Unit two to the second-semester "Comparing Political Experiences" course focuses on a specific controversial political issue: court-ordered busing in Boston. A documentary approach represents the core of instruction in this 12th-grade unit. This approach avoids lengthy narratives of a theoretical approach and yet is more in-depth than the…

  11. Clean Air Now: Political Issues. Comparing Political Experiences, Experimental Edition.

    ERIC Educational Resources Information Center

    Gillespie, Judith A.; Lazarus, Stuart

    The fourth unit to the second-semester "Comparing Political Experiences" course focuses on a specific, controversial, political issue. Using a documentary approach, this unit analyzes the concept of political change by examining the changes in Riverside, California, as that community confronts the issue of smog. The unit is divided into five…

  12. Evaluating synteny for improved comparative studies

    PubMed Central

    Ghiurcuta, Cristina G.; Moret, Bernard M. E.

    2014-01-01

    Motivation: Comparative genomics aims to understand the structure and function of genomes by translating knowledge gained about some genomes to the object of study. Early approaches used pairwise comparisons, but today researchers are attempting to leverage the larger potential of multi-way comparisons. Comparative genomics relies on the structuring of genomes into syntenic blocks: blocks of sequence that exhibit conserved features across the genomes. Syntenic blocs are required for complex computations to scale to the billions of nucleotides present in many genomes; they enable comparisons across broad ranges of genomes because they filter out much of the individual variability; they highlight candidate regions for in-depth studies; and they facilitate whole-genome comparisons through visualization tools. However, the concept of syntenic block remains loosely defined. Tools for the identification of syntenic blocks yield quite different results, thereby preventing a systematic assessment of the next steps in an analysis. Current tools do not include measurable quality objectives and thus cannot be benchmarked against themselves. Comparisons among tools have also been neglected—what few results are given use superficial measures unrelated to quality or consistency. Results: We present a theoretical model as well as an experimental basis for comparing syntenic blocks and thus also for improving or designing tools for the identification of syntenic blocks. We illustrate the application of the model and the measures by applying them to syntenic blocks produced by three different contemporary tools (DRIMM-Synteny, i-ADHoRe and Cyntenator) on a dataset of eight yeast genomes. Our findings highlight the need for a well founded, systematic approach to the decomposition of genomes into syntenic blocks. Our experiments demonstrate widely divergent results among these tools, throwing into question the robustness of the basic approach in comparative genomics. We have taken

  13. Strategies for comparing LES and experimental data of urban turbulence

    NASA Astrophysics Data System (ADS)

    Hertwig, D.; Nguyen van yen, R.; Patnaik, G.; Leitl, B.

    2012-12-01

    Unsteady flow within and above built environments is an important example of the complex nature of near-surface atmospheric turbulence. Typically, obstacle-resolving micro-scale meteorological models based on the Reynolds-averaged conservation equations are adopted to investigate and predict the mean-states of urban flow phenomena. The rapid advancements in computer capacities, however, fostered the use of time-resolved approaches like large-eddy simulation (LES) for applications on the urban micro-scale. LES has the potential to provide a realistic picture of the spatio-temporal behavior of turbulent flows within and above the urban canopy layer, which cannot be easily achieved with classic in-situ micro-meteorological measurements. The further success of eddy-resolving techniques, however, is coupled to the critical assessment of the model performance in terms of a rigorous validation against suitable reference data. This task is particularly challenging with regard to the time-dependent nature of the problem and the need to verify whether the model predicts turbulence structures in a realistic way. In this study, a hierarchy of validation strategies for urban LES flow fields is formulated and systematically applied. The test case is neutrally stratified turbulent flow in the inner city of Hamburg, Germany. The LES computations were conducted by the U.S. Naval Research Laboratory on the basis of a monotone integrated LES methodology. Reference experiments in terms of single-point, high resolution time-series measurements were carried out in the boundary-layer wind-tunnel facility at the University of Hamburg. The wind-tunnel model was built on a scale of 1:350 and included building structures with a full-scale spatial resolution of 0.5 m. Benchmark parameters for the congruent representation of atmospheric inflow conditions in the physical and the numerical model were obtained from long-term sonic anemometer measurements at a suburban meteorological field site

  14. Technology-Enhanced Consultation in Counselling: A Comparative Study

    ERIC Educational Resources Information Center

    Astramovich, Randall L.; Jones, W. Paul; Coker, J. Kelly

    2004-01-01

    Two quasi-experimental studies comparing technology-enhanced counselling consultation were conducted with a sample of 147 students enrolled in an undergraduate counselling and consultation course for elementary and secondary teachers. Study 1 (N = 76) compared the effectiveness of counselling consultation using telephone, text chat, or text chat…

  15. Pairing Fluctuations Above Tc: A Comparative Study

    NASA Astrophysics Data System (ADS)

    Verga, Simona; Gooding, Robert J.; Marsiglio, Frank

    2003-03-01

    Although the investigation of superconductivity in High Tc Cuprates has been extensive, its microscopic origin is still under debate. An important experimental fact is the universality of many properties of the cuprates (the low dimensionality, the d-wave symmetry of the superconducting gap and the pseudogap), which must be reproduced by any competitive theory. While there is no consensus about the 'glue' that binds two electrons in a pair, one can gain insight by simply providing it, without questioning its nature. The Attractive Hubbard Model for electrons on a lattice provides the means for such an approach, but even if it simplifies the picture considerably, in the coupling regime of interest one needs to rely on approximate theories. We present a comparative study of different versions of the T-matrix approximation in the atomic limit (strong coupling), where the existence of analytical solutions enables us to test how well the approximations work. We also employ a non-perturbative approach due to Y. M. Vilk and A.-M. S. Tremblay and compare it with the T-matrix and the analytical solutions. We discuss the relevance of such a study for other coupling regimes and more realistic models.

  16. Experimental and modeling study on char combustion

    SciTech Connect

    J. Yu; M.C. Zhang

    2009-05-15

    In this study, on the basis of experimental verifications with an FTIR online measurement system, theoretical calculations by using the strict continuous-film model were first compared with those by the simple single-film model that is still widely used in mathematical modeling of pulverized coal flames. The results indicated that the single-film model has some significant errors in its predictions of the ignition temperature and the combustion following ignition and hence should have some restrictions on its application. Then an improved char combustion model has been presented, taking into consideration the influence of the finite-rate heterogeneous reduction and oxidation reactions. This model gives the explicit algebraic expressions for the overall rate of combustion, the surface temperature of the particle, and the gas temperature at the flame sheet. Compared with the single-film model, predictions by the present model were in much better agreement with those predicted by the continuous-film model and the experimental data. The novel model is also much easier to be integrated into the comprehensive computing codes for industrial pulverized coal flame than the continuous-film model. 21 refs., 14 figs.

  17. An experimental Lagrangian study of inhomgeneous turbulence

    NASA Astrophysics Data System (ADS)

    Stelzenmuller, Nickolas; Mordant, Nicolas

    2015-11-01

    We investigate experimentally the Lagrangian properties of inhomogeneous turbulence in the general scope of dispersion studies in natural and industrial flows. Lagrangian studies of homogeneous turbulence are becoming common, but very little Lagrangian experimental data exists for inhomogeneous turbulence despite the vast range of applications. Particle tracking velocimetry using a very high speed camera in a fully developed turbulent channel flow in water is achieved at ReH = 33 , 000 . This technique provides Lagrangian velocity and acceleration statistics fully resolved at the smallest turbulent scales near the wall. These statistics, conditioned by the distance to the wall, allow the the investigation of the inhomogeneity of the statistical properties of this flow. Autocorrelations of velocity and acceleration show increasing Lagrangian turbulent scales as distance from the wall increases, as well as decreasing anisotropy. PDF's and moments of Lagrangian quantities are presented by showing the evolution of structure functions across the boundary layer. These results are compared to direct numerical simulation results from a similar flow, and their implications for stochastic models of inhomogeneous flows are discussed.

  18. A Numerical/Experimental Study of Nitinol Actuator Springs

    NASA Astrophysics Data System (ADS)

    Auricchio, Ferdinando; Scalet, Giulia; Urbano, Marco

    2014-07-01

    This study deals with the numerical modeling, simulation and experimental analysis of shape-memory alloy (SMA) helicoidal springs. An experimental campaign is conducted on both SMA straight wires and helicoidal springs that experienced the same annealing process. Then, we use such experimental results to investigate three phenomenological constitutive models able to represent SMA macroscopic behavior. In particular, after the identification of all the material parameters from experimental results on SMA wires, we inspect the thermo-mechanical behavior of SMA helicoidal springs by comparing numerical predictions to experimental data. Finally, we discuss models capabilities and some aspects characterizing SMA material behavior.

  19. Numerical and Experimental Study of Levee Breach

    NASA Astrophysics Data System (ADS)

    Elalfy, E. Y.; LaRocque, L.; Riahi-Nezhad, C. K.; Chaudhry, H.

    2014-12-01

    Levees are constructed along rivers and channels for flood protection. Failure of these levees can cause loss of life and property damage. A better understanding of the flow field from a levee breach allows the decision maker to assess risks and to prepare emergency plans. For this purpose, a two-dimensional numerical model is developed to simulate the levee breach. The model solves the shallow-water equations using the MacCormack explicit, finite- difference two-step, predictor-corrector scheme. The scheme is second-order accurate in time and space. The artificial viscosity technique is used to smooth the high-frequency oscillations in the computed results. The numerical results compare satisfactorily with the experimental results. A parametric study is carried-out to investigate the effect of main channel width, breach width on the computed flow field.

  20. Experimental rotor-stator cavity ingress study

    SciTech Connect

    Fox, M.; Glezer, B.

    1999-07-01

    An experimental facility has been constructed in order to study the problems of hot gas ingress and heat transfer in an engine-realistic rotor-stator cavity. This paper describes the facility, and presents detailed baseline measurements of gas ingress on the stator using a carbon-dioxide tracer method. Tests were conducted with and without a rim seal, with two axial rotor-stator spacings, and for two methods of injecting the disk cavity buffer air: axially through a central hole in the stator and through rim impingement. A cross section of the facility is shown. The data show the importance, for ingress prevention, of the detailed geometry in the region of the disk rim, as well as provides qualitative data which can be used as a guideline by the engine designer. The current data are compared, finally, to those of other researchers in the field.

  1. Experimental study and evaluation of radioprotective drugs

    NASA Technical Reports Server (NTRS)

    Smith, D. E.; Thomson, J. F.

    1968-01-01

    Experimental study evaluates radioprotective drugs administered before exposure either orally or intravenously. Specifically studied are the sources of radiation, choice of radiation dose, choice of animals, administration of drugs, the toxicity of protective agents and types of protective drug.

  2. Scatterometry or imaging overlay: a comparative study

    NASA Astrophysics Data System (ADS)

    Hsu, Simon C. C.; Pai, Yuan Chi; Chen, Charlie; Yu, Chun Chi; Hsing, Henry; Wu, Hsing-Chien; Kuo, Kelly T. L.; Amir, Nuriel

    2015-03-01

    Most fabrication facilities today use imaging overlay measurement methods, as it has been the industry's reliable workhorse for decades. In the last few years, third-generation Scatterometry Overlay (SCOL™) or Diffraction Based Overlay (DBO-1) technology was developed, along another DBO technology (DBO-2). This development led to the question of where the DBO technology should be implemented for overlay measurements. Scatterometry has been adopted for high volume production in only few cases, always with imaging as a backup, but scatterometry overlay is considered by many as the technology of the future. In this paper we compare imaging overlay and DBO technologies by means of measurements and simulations. We outline issues and sensitivities for both technologies, providing guidelines for the best implementation of each. For several of the presented cases, data from two different DBO technologies are compared as well, the first with Pupil data access (DBO-1) and the other without pupil data access (DBO-2). Key indicators of overlay measurement quality include: layer coverage, accuracy, TMU, process robustness and robustness to process changes. Measurement data from real cases across the industry are compared and the conclusions are also backed by simulations. Accuracy is benchmarked with reference OVL, and self-consistency, showing good results for Imaging and DBO-1 technology. Process sensitivity and metrology robustness are mostly simulated with MTD (Metrology Target Designer) comparing the same process variations for both technologies. The experimental data presented in this study was done on ten advanced node layers and three production node layers, for all phases of the IC fabrication process (FEOL, MEOL and BEOL). The metrology tool used for most of the study is KLA-Tencor's Archer 500LCM system (scatterometry-based and imaging-based measurement technologies on the same tool) another type of tool is used for DBO-2 measurements. Finally, we conclude that

  3. Comparative mirror cleaning study: a study on removing particulate contamination

    NASA Astrophysics Data System (ADS)

    Houston, Karrie D.

    2006-08-01

    A mirror cleaning study was conducted to assess the effectiveness of three cleaning methods in their ability to remove particulate contamination from reflective mirror surfaces. Presently, the detergent bath, solvent rinse, and CO II snow cleaning methods are the most commonly used optical cleaning techniques within the optics industry. These techniques are also commonly used by the Optics Branch/Code 551 at Goddard Space Flight Center (GSFC) to remove particulate contamination from optical surfaces. In this experimental study, the above-mentioned cleaning methods were used to clean twelve uncoated silicon wafers, twelve gold coated silicon wafers, and twelve gold coated silicon wafers with a silicon oxide protective coating. CO II snow cleaning had an average removal percentage of 84%, followed by the solvent rinse at 74%, and the detergent bath at 61%. In addition to the average removal percentage, this comparative study was designed to: (1) determine the cleaning ability of each method based on the number and size of removed particles; (2) assess the risk of surface damage for each cleaning procedure; (3) evaluate each cleaning method as a function of its initial "qualitative" contamination level ("fairly clean", "dirty", and "very dirty"). The particulate cleanliness of all wafers was characterized using Image Analysis and Image-Pro Plus 5.0 software. In addition, the experimental design and experimental results were analyzed using JMP/Statistical Analytical Software Version 6.0.

  4. An experimental study on microwave electron gun

    SciTech Connect

    Wang, G.; Wu, J.; Wang, Y.

    1995-12-31

    We report both the simulation and experimental results of using a ring cathode instead of the solid cathode to reduce the back bombardment effect of a thermionic cathode microwave electron gun. The result shows that the back bombardment power is decreased about 2/3 without changing the beam quality apparently which allows operation at higher repetition rate. Experimental results are compared with the simulation with good agreement.

  5. Continuous game dynamics: an experimental study.

    SciTech Connect

    Patelli, P.; Sato, Yuzuru

    2004-01-01

    In this paper we study an experiment with human agents strategically interacting in a game characterized by continuous time and continuous strategy space. The research is focused in studying the agents interaction dynamic under different experimental settings. The agents play a two person game that is an extension of the classic Cournot duopoly. Having agents making decision continuously allows us to track the temporal structure of strategy evolution very precisely. We can follow the agents continuous behavior evolution avoiding the data under-sampling. To our knowledge this is the first attempt to approach experimentally the continuous time decision making. We also emphasize that the focus of our work is not the Cournot model but rather the more general problem of studying the agents strategic interaction dynamic in continuous space time. Flaming the problem as the well studied Cournot Duopoly would be a good starting point. In economics dynamics studies the oligopoly model literature in both discrete and continuous time is one of the richest. There is also a vast literature in experimental economics about repeated games in general and more specifically in duopoly/oligopoly models. Cox and Walker studied whether subjects can learn to play the Cournot Duopoly strategies comparing the experimental results with the theoretical prediction of learning models. The Cox Walker experiment differs from our settings because it is in discrete time and is an evolutionary dynamics framework through a random matching mechanism of the experimental subjects. From the theoretical perspective many works have been focused in studying the Cournot model in a dynamical settings. Okuguchi and Szidarovsky formulated a continuous time version of the Cournot Oligopoly with multiproduct firms. They analyzed the stability of the equilibrium and proved that it is stable, under certain conditions, independently from the value of the adjustments. Chiarella and Khomin extended this analysis to

  6. Comparative hydraulics of two fishery research circular tanks and recommendations for control of experimental bias

    USGS Publications Warehouse

    Odeh, M.; Schrock, R.M.; Gannam, A.

    2003-01-01

    Hydraulic characteristics inside two research circular tanks (1.5-m and 1.2-m diameter) with the same volume of water were studied to understand how they might affect experimental bias by influencing the behavior and development of juvenile fish. Water velocities inside each tank were documented extensively and flow behavior studied. Surface inflow to the 1.5-m tank created a highly turbulent and aerated surface, and produced unevenly distributed velocities within the tank. A low-flow velocity, or "dead" zone, persisted just upstream of the surface inflow. A single submerged nozzle in the 1.2-m tank created uniform flow and did not cause undue turbulence or introduce air. Flow behavior in the 1.5-m tank is believed to have negatively affected the feeding behavior and physiological development of a group of juvenile fall chinook salmon, Oncorhynchus tshawytscha. A new inflow nozzle design provided comparable flow behavior regardless of tank size and water depth. Maintaining similar hydraulic conditions inside tanks used for various biological purposes, including fish research, would minimize experimental bias caused by differences in flow behavior. Other sources of experimental bias are discussed and recommendations given for reporting and control of experimental conditions in fishery research tank experiments.

  7. Experimental Modeling of Proliferative Vitreoretinopathy. An Experimental Morphological Study.

    PubMed

    Khoroshilova-Maslova, I P; Leparskaya, N L; Nabieva, M M; Andreeva, L D

    2015-05-01

    A model of proliferative vitreoretinopathy induced by simultaneous intravitreal injection of recombinant IL-1β and platelet concentrate is created and its main morphological manifestations are studied on Chinchilla rabbits. The model reflects pathogenesis of proliferative vitreoretinopathy: epiretinal membrane with the formation of retinal plication, traction detachment of the retina; moderate inflammatory reaction in the uveal tract, in the optic nerve infundibulum, in the vitreous body; intact structural elements of the retina, dissociation of the retinal pigmented epithelium cells with their subsequent migration. The model is adequate to the clinical picture of proliferative vitreoretinopathy in humans, which recommends it for experimental studies of the efficiency of drug therapy and prevention of this disease. PMID:26033599

  8. Comparative evaluation of maintenance of cell viability of an experimental transport media “coconut water” with Hank's balanced salt solution and milk, for transportation of an avulsed tooth: An in vitro cell culture study

    PubMed Central

    Thomas, Toby; Gopikrishna, Velayutham; Kandaswamy, Deivanayagam

    2008-01-01

    The purpose of this study was to evaluate the efficiency of a new storage medium, coconut water, in comparison with other traditional storage media like Hank's balanced salt solution (HBBS) and milk, in maintaining the viability of an established cell line BHK-21/C13 (baby hamster kidney fibroblasts) using the direct suspension cell culture technique. The storage media tested in the study were divided into three major groups and two control groups - Group A: HBBS, Group B: milk, and Group C: coconut water. The positive and negative controls corresponded to 0-minute and 24-hour dry times respectively. The three groups were then divided into five subgroups, each denoting the storage time periods 15 min, 30 min, 45 min, 60 min and 120 min respectively. The cell line BHK-21/C13 was subcultured and the number of cells was standardized by making a cell suspension using Minimal Essential Medium in five culture plates. One ml of each experimental group (HBBS, milk and coconut water) was added to eight wells of each culture plate. The culture plates containing the cells and the experimental groups were incubated for the respective time periods. The cells were then counted with a Neubauer counting chamber, under light microscope. The results were statistically analyzed using One-way ANOVA and Multiple Range Test using the Tukey-HSD procedure to identify the significant groups at p ≤ 0.05. Within the parameters of this study, it appears that coconut water may be a better alternative to HBSS or milk, in terms of maintaining cell viability. Coconut water can be used as a superior transport medium for avulsed teeth. PMID:20142880

  9. Experimental Structural Studies of Solutes in Aqueous Solution

    SciTech Connect

    Persson, Ingmar

    2007-11-29

    The principles of experimental methods to study the structure and the hydrogen bonding of hydrated solutes in aqueous solution are presented, and whether theoretical simulations can produce comparable information as the experimental ones is discussed. Two structure methods, extended X-ray absorption fine structure (EXAFS) and large angle X-ray scattering (LAXS), and one method to study the hydrogen bonding in hydrated species in aqueous solution, double difference infrared spectroscopy of HDO, are presented.

  10. Solvent influence on the excited states of the oxo form of barbituric acid and the mechanisms of the out-of-plane non-radiative elongation of the Nsbnd H bond: A comparative theoretical and experimental study

    NASA Astrophysics Data System (ADS)

    Shterev, Ivan G.; Delchev, Vassil B.

    The solvent influence on the excited states, emission and absorption energies of the oxo for of barbituric acid was studied with experimental (UV and fluorescence spectra) and theoretical methods. The excited-state reaction paths of the out-pf-plane elongation of the Nsbnd H bond of the oxo form of barbituric acid were also investigated (TD DFT level) to the conical intersections mediating internal conversions to the ground state. The 1nσ* excited state was found to be the driven electronic state. We found that the increase of the polarity of the solvent reduces the 1nσ* excited state decay rate through a non-planar conical intersection and increases its energy. Thus, solvents with higher polarity disfavor the non-radiative decay through conical intersections.

  11. Experimental Study of Alluvial Fan Formation

    NASA Astrophysics Data System (ADS)

    Delorme, P.; Devauchelle, O.; Barrier, L.; Métivier, F.

    2015-12-01

    At the outlet of mountain ranges, rivers flow onto flatter lowlands. The associated change of slope causes sediment deposition. As the river is free to move laterally, it builds conical sedimentary structures called alluvial fans. Their location at the interface between erosional and depositional areas makes them valuable sedimentary archives. To decipher these sedimentary records, we need to understand the dynamics of their growth. Most natural fans are built by braided streams. However, to avoid the complexity of braided rivers, we develop a small-scale experiment in which an alluvial fan is formed by a single channel. We use a mixture of water and glycerol to produce a laminar river. The fluid is mixed with corindon sand (~ 300 μm) in a tilted channel and left free to form a fan around its outlet. The sediment and water discharges are constant during an experimental run. We record the fan progradation and the channel morphology with top-view pictures. We also generate an elevation map with an optical method based on the deformation of a moiré pattern. We observe that, to leading order, the fan remains self-affine as it grows, with a constant slope. We compare two recent studies about the formation of one-dimensionnal fan [Guerit et al. 2014] and threshold rivers [Seizilles et al. 2013] to our experimental findings. In particular, we propose a theory witch relates the fan morphology to the control parameters ( fluid and sediment discharges, grain size). Our observation accord with the predictions, suggesting that the fan is built near the threshold of sediment motion. Finally, we intend to expand our interpretation to alluvial fans build by single-thread channels ( Okavango, Bostwana; Taquari and Paraguay, Brasil; Pastaza, Peru).

  12. Teaching the Comparative Approach to American Studies.

    ERIC Educational Resources Information Center

    Seaberg, Stanley

    The rationale behind this book of five suggested or sample comparative units contains several elements: 1) an interdisciplinary social science approach to studying the American past, present, and future; and 2) a view of our country's history in terms of a world setting and in the light on contemporary concerns. The global comparative method…

  13. Comparative Environmental Threat Analysis: Three Case Studies.

    ERIC Educational Resources Information Center

    Latour, J. B.; Reiling, R.

    1994-01-01

    Reviews how carrying capacity for different environmental problems is operationalized. Discusses whether it is possible to compare threats, using the exceeding of carrying capacity as a yardstick. Points out problems in comparative threat analysis using three case studies: threats to European groundwater resources, threats to ecosystems in Europe,…

  14. Fractional calculus in viscoelasticity: An experimental study

    NASA Astrophysics Data System (ADS)

    Meral, F. C.; Royston, T. J.; Magin, R.

    2010-04-01

    Viscoelastic properties of soft biological tissues provide information that may be useful in medical diagnosis. Noninvasive elasticity imaging techniques, such as Magnetic Resonance Elastography (MRE), reconstruct viscoelastic material properties from dynamic displacement images. The reconstruction algorithms employed in these techniques assume a certain viscoelastic material model and the results are sensitive to the model chosen. Developing a better model for the viscoelasticity of soft tissue-like materials could improve the diagnostic capability of MRE. The well known "integer derivative" viscoelastic models of Voigt and Kelvin, and variations of them, cannot represent the more complicated rate dependency of material behavior of biological tissues over a broad spectral range. Recently the "fractional derivative" models have been investigated by a number of researchers. Fractional order models approximate the viscoelastic material behavior of materials through the corresponding fractional differential equations. This paper focuses on the tissue mimicking materials CF-11 and gelatin, and compares fractional and integer order models to describe their behavior under harmonic mechanical loading. Specifically, Rayleigh (surface) waves on CF-11 and gelatin phantoms are studied, experimentally and theoretically, in order to develop an independent test bed for assessing viscoelastic material models that will ultimately be used in MRE reconstruction algorithms.

  15. Experimental Study on Revetec Engine Cam Performance

    NASA Astrophysics Data System (ADS)

    Mohyeldin Gasim, Maisara; Giok Chui, Lee; Anwar, Khirul Azhar bin

    2012-09-01

    In Revetec engine (three-lobed) cam replaces the crankshaft to convert the reciprocating motion of the engine piston, to a rotating motion in the drive line. Since the cam controls the piston movement, the cam profile has a great effect on engine performance. In this paper an experimental study was done to a (three- lobed) cam with Cycloidal motion profile but with different ratios between the base circle radius of the cam and the radius of the roller follower. DEWESoft was used to find the displacement and the vibration of the piston, and compare the actual results from the test with the theoretical results from the cam profile equation. The results showed that there is a periods of miss contact between the follower and the cam when the ratio between the base circle radius of the cam and the radius of the roller follower is less than a certain value, and also increasing of vibration. The suggested ratio between the cam and follower radius is to be more than 2:1.

  16. Efficiency study comparing two helicopter planetary reduction stages

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.; Handschuh, Robert F.

    1990-01-01

    A study was conducted to compare the efficiency of two helicopter transmission planetary reduction stages. Experimental measurements and analytical predictions were made. The analysis predicted and experiments verified that one planetary stage was a more efficient design due to the type of planet bearing used in the stage. The effects of torque, speed, lubricant type, and lubricant temperature on planetary efficiency are discussed.

  17. Experimental design of a waste glass study

    SciTech Connect

    Piepel, G.F.; Redgate, P.E.; Hrma, P.

    1995-04-01

    A Composition Variation Study (CVS) is being performed to support a future high-level waste glass plant at Hanford. A total of 147 glasses, covering a broad region of compositions melting at approximately 1150{degrees}C, were tested in five statistically designed experimental phases. This paper focuses on the goals, strategies, and techniques used in designing the five phases. The overall strategy was to investigate glass compositions on the boundary and interior of an experimental region defined by single- component, multiple-component, and property constraints. Statistical optimal experimental design techniques were used to cover various subregions of the experimental region in each phase. Empirical mixture models for glass properties (as functions of glass composition) from previous phases wee used in designing subsequent CVS phases.

  18. Experimental and Modeling Studies of Massif Anorthosites

    NASA Technical Reports Server (NTRS)

    Longhi, John

    1999-01-01

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

  19. Experimental study of burnout in channels with twisted fuel rods

    NASA Astrophysics Data System (ADS)

    Bol'Shakov, V. V.; Bashkirtsev, S. M.; Kobzar', L. L.; Morozov, A. G.

    2007-05-01

    The results of experimental studies of pressure drop and critical heat flux in the models of fuel assemblies (FAs) with fuel rod simulators twisted relative to the longitudinal axis and a three-ray cross section are considered. The experimental data are compared to the results obtained with the use of techniques adopted for design calculations with fuel rod bundles of type-VVER reactors.

  20. [Comparative efficacy of albendazole and mebendazole oily suspensions in albino mice with experimental larval alveococcosis].

    PubMed

    Kovalenko, F P; Kukhaleva, I V; Shkoliar, N A; Legon'kov, Iu A

    2013-01-01

    The comparative efficacy of albendazole and mebendazole oily suspensions (AOS and MOS) was studied in an experimental model of experimental larval alveococcosis in albino mice. The animals were intragastrically injected with the agents once daily for 40 days on day 35 after intraperitoneal inoculation with E. multilocularis acephalocysts. They were dissected 29 days after treatment termination (103 days following inoculation) and the rate of infestation and viability and the degree of maturity of developed alveococcosis larvocysts (AL) were determined. The AOS and MOS efficiency estimated by the mean mass of AL per animal was 83.3 and 98.1%, respectively; whereas the similar indicator calculated by one largest AL weight per animal found among all the animals in the compared groups was equal to 57.7 and 96.9%, respectively. Under the equal conditions of solubilization in vegetable oil, the biological activity and bioavailability of mebendazole were shown to increase to a much greater extent than those of albendazole. The findings suggest that the use of mebendazole is promising for designing new vegetable oil-based formulations of the agent. PMID:24003516

  1. Experimental Approaches to Studying Biological Electron Transfer.

    ERIC Educational Resources Information Center

    Scott, Robert A.; And Others

    1985-01-01

    Provides an overview on biological electron-transfer reactions, summarizing what is known about how distance, spatial organization, medium, and other factors affect electron transfer. Experimental approaches, including studies of bimolecular electron transfer reactions (electrostatic effects and precursor complexes), are considered. (JN)

  2. Experimental Studies on Biosensing by SPR

    NASA Astrophysics Data System (ADS)

    Sun, Xiaochun; Shiokawa, Showko; Matsui, Yosikazu

    1989-09-01

    Biosensing using surface plasmon resonance is experimentally studied. The results obtained by detecting the bioresponse of the α-Feto protein system and cyclic experiments show that this technique has potential application in the field of biosensing. The effects of an organic layer on detecting sensitivity and restoration of sensors are also discussed.

  3. Numerical and experimental study of shock-driven cavity collapse

    NASA Astrophysics Data System (ADS)

    Betney, M. R.; Anderson, P. A.; Doyle, H.; Tully, B.; Hawker, N. A.; Ventikos, Y.

    2015-12-01

    A study is presented of the interaction of a shock wave with gas cavities cast in a hydrogel. Simulations are conducted using a front-tracking approach, whereby Lagrangian hypersurfaces are used to model the interface between materials. These ‘fronts’ are overlaid on an Eulerian grid which is used to model the bulk flow. Results are compared to an experimental investigation, in which a light gas gun is used to create ∼600 MPa shock waves in hydrogel blocks, within which air cavities have been cast. Experimental results are presented, including temporally resolved measurements of light emission. Comparison between experimental and simulated results shows good agreement.

  4. Experimental and simulation studies of alignment marks

    NASA Astrophysics Data System (ADS)

    Wong, Alfred K. K.; Doi, Takeshi; Dunn, Diana D.; Neureuther, Andrew R.

    1991-07-01

    The roles of alignment mark structure, geometry, film materials and scanned illumination image on dark-field alignment signal quality are investigated through simulation interpreted experiments. The illumination of the alignment system consists of a low numerical aperture 1.0 micrometers image of a slit at 488.0 and 514.5 nm which is scanned across the alignment mark. The light scattered into a dark-band protected cone is collected. The structures consist of 0.5 to 1.2 micrometers wide features including trenches in silicon coated with 1.34 micrometers of photoresist, and trenches in nitride coated silicon with 1.00 micrometers of photoresist. For simulation, the illumination image is calculated using SAMPLE and input to a massively parallel finite-difference time-domain scattering analysis program called TEMPEST at various lateral shifts to simulate scanning. The diffracted orders output from TEMPEST are used to calculate total diffracted energy in various angular bands and to view dark field instantaneous images. Studied of depth, width, thin-film stack and coating thickness are used to identify key phenomena such as the role of interference between reflection from the alignment mark and substrate surfaces. Simulations are used to interpret the experimental observations and provide guidelines for topography control, and illumination and collection optics. The alignment signal is shown to be a strong function of trench depth, and only a weak function of trench width. An order of magnitude signal strength reduction occurs when the effective optical depth of the trench is a multiple of (lambda) resist/2 compared to the surrounding area.

  5. Species comparative studies and cognitive development.

    PubMed

    Gómez, Juan-Carlos

    2005-03-01

    The comparative study of infant development and animal cognition brings to cognitive science the promise of insights into the nature and origins of cognitive skills. In this article, I review a recent wave of comparative studies conducted with similar methodologies and similar theoretical frameworks on how two core components of human cognition--object permanence and gaze following--develop in different species. These comparative findings call for an integration of current competing accounts of developmental change. They further suggest that evolution has produced developmental devices capable at the same time of preserving core adaptive components, and opening themselves up to further adaptive change, not only in interaction with the external environment, but also in interaction with other co-developing cognitive systems. PMID:15737820

  6. A comparative study between shielded and open coplanar waveguide discontinuities

    NASA Technical Reports Server (NTRS)

    Dib, Nihad I.; Harokopus, W. P., Jr.; Ponchak, G. E.; Katehi, L. P. B.

    1993-01-01

    A comparative study between open and shielded coplanar waveguide (CPW) discontinuities is presented. The space domain integral equation method is used to characterize several discontinuities such as the open-end CPW and CPW series stubs. Two different geometries of CPW series stubs (straight and bent stubs) are compared with respect to resonant frequency and radiation loss. In addition, the encountered radiation loss due to different CPW shunt stubs is evaluated experimentally. The notion of forced radiation simulation is presented, and the results of such a simulation are compared to the actual radiation loss obtained rigorously. It is shown that such a simulation cannot give reliable results concerning radiation loss from printed circuits.

  7. A Comparative Study of Sparse Associative Memories

    NASA Astrophysics Data System (ADS)

    Gripon, Vincent; Heusel, Judith; Löwe, Matthias; Vermet, Franck

    2016-05-01

    We study various models of associative memories with sparse information, i.e. a pattern to be stored is a random string of 0s and 1s with about log N 1s, only. We compare different synaptic weights, architectures and retrieval mechanisms to shed light on the influence of the various parameters on the storage capacity.

  8. The Student Teaching Experience: A Comparative Study.

    ERIC Educational Resources Information Center

    Butler, Judy D.

    This paper describes a 1996 study that compared the student teaching experiences of a traditional and a nontraditional student to ascertain what differences in their experiences might imply about teacher preparation. The two students kept journals that could be written in at any time of the day. They recorded their impressions of their situation…

  9. A Comparative Study of Sparse Associative Memories

    NASA Astrophysics Data System (ADS)

    Gripon, Vincent; Heusel, Judith; Löwe, Matthias; Vermet, Franck

    2016-07-01

    We study various models of associative memories with sparse information, i.e. a pattern to be stored is a random string of 0s and 1s with about log N 1s, only. We compare different synaptic weights, architectures and retrieval mechanisms to shed light on the influence of the various parameters on the storage capacity.

  10. Experimental and computational study of thaumasite structure

    SciTech Connect

    Scholtzová, Eva; Kucková, Lenka; Kožíšek, Jozef; Pálková, Helena; Tunega, Daniel

    2014-05-01

    The structure of thaumasite has been studied experimentally by means of a single crystal X-ray diffraction and FTIR methods, and theoretically using density functional theory (DFT) method. Very good agreement was achieved between calculated and experimental structural parameters. In addition, calculations offered the refinement of the positions of the hydrogen atoms. The detailed analysis of the hydrogen bonds existing in the thaumasite structure has been performed. Several types of hydrogen bonds have been classified. The water molecules coordinating Ca{sup 2+} cation act as proton donors in moderate O-H···O hydrogen bonds formed with CO₃⁻²and SO₄⁻² anions. The multiple O-H···O hydrogen bonds exist among water molecules themselves. Finally, relatively weak hydrogen bonds form water molecules with the OH groups from the coordination sphere of the Si(OH)₆⁻² anion. Further, calculated vibrational spectrum allowed complete assignment of all vibrational modes which are not available from the experimental spectrum that has a complex structure with overlapped bands, especially below 1500 cm⁻¹. Highlights: • The thaumasite structure was studied experimentally and using DFT method. • We used DFT method for the refinement of the positions of hydrogen atoms. • A detailed analysis of the hydrogen bonds was done. • A complete assignment of all bands to particular types of vibrations was done.

  11. Comparative evaluation of serum, FTA filter-dried blood and oral fluid as sample material for PRRSV diagnostics by RT-qPCR in a small-scale experimental study.

    PubMed

    Steinrigl, Adolf; Revilla-Fernández, Sandra; Wodak, Eveline; Schmoll, Friedrich; Sattler, Tatjana

    2014-01-01

    Recently, research into alternative sample materials, such as oral fluid or filter-dried blood has been intensified, in order to facilitate cost-effective and animal-friendly sampling of individuals or groups of pigs for diagnostic purposes. The objective of this study was to compare the sensitivity of porcine reproductive and respiratory syndrome virus (PRRSV)-RNA detection by reverse transcription quantitative real-time PCR (RT-qPCR) in serum, FTA filter-dried blood and oral fluid sampled from individual pigs. Ten PRRSV negative pigs were injected with an EU-type PRRSV live vaccine. Blood and oral fluid samples were taken from each pig before, and 4, 7, 14 and 21 days after vaccination. All samples were then analyzed by PRRSV RT-qPCR. In serum, eight often pigs tested RT-qPCR positive at different time points post infection. Absolute quantification showed low serum PRRSV-RNA loads in most samples. In comparison to serum, sensitivity of PRRSV-RNA detection was strongly reduced in matched FTA filter-dried blood and in oral fluid from the same pigs. These results indicate that with low PRRSV-RNA loads the diagnostic sensitivity of PRRSV-RNA detection by RT-qPCR achieved with serum is currently unmatched by either FTA filter-dried blood or oral fluid. PMID:24881272

  12. Retrievable IVC Square Stent Filter: Experimental Study

    SciTech Connect

    Pavcnik, Dusan; Uchida, Barry T.; Keller, Frederick S.; Corless, Christopher L.; Roesch, Josef

    1999-05-15

    Purpose: In vitro and in vivo evaluation of a new retrievable, home-made, inferior vena cava (IVC) Square stent filter (SSF) with two trapping levels. Methods: In vitro, the SSF was compared in a flow model with the stainless steel Greenfield filter (SGF) for emboli- trapping efficiency by serially passing 300 emboli of 3 and 6 mm in diameter and 15-30 mm in length in each type of filter. Nine swine were used for the in vivo testing of the SSF for deployment and retrievability, emboli-trapping efficiency, stability, and self-centering ability and two were used (total of 11 swine) for testing repositioning and retrievability of the SSF at 2 weeks and for gross and histologic IVC changes at 2 months. Results: In vitro, the SSF and SGF had similar efficiency in trapping large emboli but the SSF had significantly better efficiency than the SGF for trapping all sizes of emboli (91.7% vs 81%), medium size emboli (93% vs 80%), and small emboli (86% vs 69%). Efficiency decreased in both filters from the first to the fifth embolus in each series but was still significantly better for the SSF. With the SSF, 89% of emboli were caught at the primary and 11% at the secondary filtration level. In the nine animals used for acute studies, the SSF was easily placed in all 27 attempts, assumed a central position 26 times, and was easily retrieved in 21 of 22 attempts. One tilted filter needed additional manipulation for retrieval. During emboli injection in five swine, the SSF had 97.2% emboli-trapping efficiency and demonstrated good stability. In the two animals used for longer-term evaluation, the filters were easily retrieved 2 weeks after implantation. Histologic evaluation at 2 months showed neointimal proliferation around the SSF wires in contact with the IVC wall, which was otherwise normal. Conclusion: The SSF is a promising filter. It is easy to place and retrieve, is stable after placement, and has high efficiency for trapping emboli. Promising results justify further

  13. Comparative study of water reactivity with Mo{sub 2}O{sub y}{sup −} and W{sub 2}O{sub y}{sup −} clusters: A combined experimental and theoretical investigation

    SciTech Connect

    Ray, Manisha; Waller, Sarah E.; Saha, Arjun; Raghavachari, Krishnan; Jarrold, Caroline Chick

    2014-09-14

    A computational investigation of the Mo{sub 2}O{sub y}{sup −} + H{sub 2}O (y = 4, 5) reactions as well as a photoelectron spectroscopic probe of the deuterated Mo{sub 2}O{sub 6}D{sub 2}{sup −} product have been carried out to understand a puzzling question from a previous study: Why is the rate constant determined for the Mo{sub 2}O{sub 5}{sup −} + H{sub 2}O/D{sub 2}O reaction, the terminal reaction in the sequential oxidation of Mo{sub 2}O{sub y}{sup −} by water, higher than the W{sub 2}O{sub 5}{sup −} + H{sub 2}O/D{sub 2}O reaction? This disparity was intriguing because W{sub 3}O{sub y}{sup −} clusters were found to be more reactive toward water than their Mo{sub 3}O{sub y}{sup −} analogs. A comparison of molecular structures reveals that the lowest energy structure of Mo{sub 2}O{sub 5}{sup −} provides a less hindered water addition site than the W{sub 2}O{sub 5}{sup −} ground state structure. Several modes of water addition to the most stable molecular and electronic structures of Mo{sub 2}O{sub 4}{sup −} and Mo{sub 2}O{sub 5}{sup −} were explored computationally. The various modes are discussed and compared with previous computational studies on W{sub 2}O{sub y}{sup −} + H{sub 2}O reactions. Calculated free energy reaction profiles show lower barriers for the initial Mo{sub 2}O{sub y}{sup −} + H{sub 2}O addition, consistent with the higher observed rate constant. The terminal Mo{sub 2}O{sub y}{sup −} sequential oxidation product predicted computationally was verified by the anion photoelectron spectrum of Mo{sub 2}O{sub 6}D{sub 2}{sup −}. Based on the computational results, this anion is a trapped dihydroxide intermediate in the Mo{sub 2}O{sub 5}{sup −} + H{sub 2}O/D{sub 2}O → Mo{sub 2}O{sub 6}{sup −} + H{sub 2}/D{sub 2} reaction.

  14. [Experimental study of pinostrobine oxime biotransformation].

    PubMed

    Sariev, A K; Abaimov, D A; Tankevich, M V; Prokhorov, D I; Adekenov, S M; Arystan, L I; Seĭfulla, R D

    2014-01-01

    We have experimentally studied pathways of elimination of an oximized derivative of phytoflavonoid pinostrobine by HPLC/mass spectrometry. Four potential metabolites of pinostrobine oxime have been found and there was an attempt to determine their molecular structures on the basis of their fragmentation under positive electrospray ionization conditions. It is established that pinostrobine oxime is removed from the organism mainly unchanged and also in the form of glucuronated derivative. PMID:25335390

  15. In vitro assessment of solvent evaporation from commercial adhesive systems compared to experimental systems.

    PubMed

    Nihi, Fabio Mitugui; Fabre, Hebert Samuel Carafa; Garcia, Georges; Fernandes, Karen Barros Parron; Ferreira, Flaviana Bombarda de Andrade; Wang, Linda

    2009-01-01

    Solvents should be properly evaporated after application to dental substrates. The aim of this study was to assess the evaporation of commercial, experimental and neat solvents. The tested null hypotheses were that there are no differences in solvent evaporation regardless of its formulation and over time. Evaporation from commercial adhesive systems (Scotchbond Multipurpose Primer, Scotchbond Multipurpose Adhesive, Prime & Bond NT, Multi Bond, Excite, Single Bond 2, Adhese Primer, Adhese Bond, Xeno III A and Xeno III B) and experimental primers (35% HEMA plus 65% acetone or ethanol or water v/v) were compared to neat solvents (acetone, ethanol and water). Samples (10 microL) of these products were dripped into glass containers placed on a digital precision balance. Evaporation was assessed at 0, 5, 10, 15, 30, 60, 120, 300 and 600 s times to calculate mass loss. Data were analyzed statistically by ANOVA and Bonferroni's correction (a=0.05). Acetone-based products exhibited a remarkable capacity to evaporate spontaneously over time. Neat acetone evaporated significantly more than the HEMA-mixtures and the commercial formulations (p<0.05). The incorporation of monomers and other ingredients in the commercial formulations seem to reduce the evaporation capacity. Solvent evaporation was time and material-dependent. PMID:20126908

  16. Comparative study of turbulence models in predicting hypersonic inlet flows

    NASA Technical Reports Server (NTRS)

    Kapoor, Kamlesh; Anderson, Bernhard H.; Shaw, Robert J.

    1992-01-01

    A numerical study was conducted to analyze the performance of different turbulence models when applied to the hypersonic NASA P8 inlet. Computational results from the PARC2D code, which solves the full two-dimensional Reynolds-averaged Navier-Stokes equation, were compared with experimental data. The zero-equation models considered for the study were the Baldwin-Lomax model, the Thomas model, and a combination of the Baldwin-Lomax and Thomas models; the two-equation models considered were the Chien model, the Speziale model (both low Reynolds number), and the Launder and Spalding model (high Reynolds number). The Thomas model performed best among the zero-equation models, and predicted good pressure distributions. The Chien and Speziale models compared very well with the experimental data, and performed better than the Thomas model near the walls.

  17. Comparative study of turbulence models in predicting hypersonic inlet flows

    NASA Technical Reports Server (NTRS)

    Kapoor, Kamlesh; Anderson, Bernhard H.; Shaw, Robert J.

    1992-01-01

    A numerical study was conducted to analyze the performance of different turbulence models when applied to the hypersonic NASA P8 inlet. Computational results from the PARC2D code, which solves the full two-dimensional Reynolds-averaged Navier-Stokes equation, were compared with experimental data. The zero-equation models considered for the study were the Baldwin-Lomax model, the Thomas model, and a combination of the Baldwin-Lomax and Thomas models; the two-equation models considered were the Chien model, the Speziale model (both low Reynolds number), and the Launder and Spalding model (high Reynolds number). The Thomas model performed best among the zero-equation models, and predicted good pressure distributions. The Chien and Speziale models compared wery well with the experimental data, and performed better than the Thomas model near the walls.

  18. Experimental study of the chaotic waterwheel

    NASA Astrophysics Data System (ADS)

    Rutherford, George; Erxleben, Amy; Rosa, Epaminondas, Jr.

    2007-03-01

    The chaotic waterwheel is often given as an example of a mechanical system that can exhibit chaotic behavior. Its early demonstration by Malkus and the realization that it can be modeled by the Lorenz equations has secured it a prominent place in almost every general presentation of chaos. It seems quite surprising, then, that no experimental investigations of this textbook system have ever been published. To fill this historic gap, and to initiate an experimental study of this incredibly rich dynamic system, our lab has constructed a research-grade waterwheel consisting of a vacuum-formed polycarbonate frame in which 36 cylindrical cells are mounted on an 18 inch diameter. The wheel and its axis can be tilted, and water is fed into the top of the wheel and drains out through thin tubes at the bottom of each cell. An aluminum skirt at the wheel's periphery passes through a variable gap magnet to provide magnetic braking. Angular time series data are collected with an absolute rotary encoder. The data are smoothed and angular velocity and acceleration are calculated via fast fourier transforms. The data show quasi-uniform rotation as well as periodic and chaotic motion and agree fairly well with computer simulations of the idealized wheel equations. We will discuss differences between the experimental data and the simulation predictions as well as plans for future studies.

  19. Experimental Study of Athermal Elastic Network Mechanics

    NASA Astrophysics Data System (ADS)

    Michel, Jonathan; Yunker, Peter

    Recently, significant theoretical effort has been directed towards understanding the mechanics of networks. Elastic networks are of inherent fundamental interest and serve as useful analogs for describing other physical systems. Recent applications include modeling of collagen and descriptions of jamming in granular media and glass formation. I propose to discuss ongoing experimental efforts to study mechanical properties of elastic networks, such as Young's modulus and ultimate strength, in the athermal limit. I will begin with the simple case of regular, isostatic crystalline lattices and proceed to studies of random, connected elastic networks of varying bond number for a given number of lattice sites, including both isostatic and sub-isostatic networks.

  20. A Comparative Study of Heat Transfer in Metallic Materials

    NASA Astrophysics Data System (ADS)

    Pǎucǎ, Adina; Hepuţ, Teodor; Pinca-Bretotean, Camelia; Stoica, Diana

    2011-09-01

    Rolling of metallic materials with heat transfer occurs as a result of interaction between the workpiece and the rolling cylinders incandescent. Heat transferred by diffusion into the cylinders generates variable temperature fields. These fields produce variable temperature thermal stress in each rotation cycle of rolling cylinders. This paper aims at mathematical modeling of variable temperature fields, using Matlab. These diagrams obtained are compared with those obtained following experimental study of the thermal lamination cylinders for 5 states isochronous temperature.

  1. Experimental and theoretical study of ornidazole

    NASA Astrophysics Data System (ADS)

    Rajesh, P.; Gunasekaran, S.; Gnanasambandan, T.; Seshadri, S.

    2016-01-01

    The Fourier transform infrared (FT-IR) and the Fourier transform Raman (FT-Raman) spectra of the title molecule in solid phase were recorded in the region 4000-400 cm- 1 and 4000-100 cm- 1 respectively. The geometrical parameters and energies were investigated with the help of Density Functional Theory (DFT) employing B3LYP method and 6-31G (d, p) basis set. The analysis was supported by electrostatic potential maps and calculation of HOMO-LUMO. UV, FT-IR and FT-Raman spectra of ornidazole were calculated and compared with experimental results. Thermodynamic properties like entropy, heat capacity, have been calculated for the molecule. The predicted first hyperpolarizability also shows that the molecule might have a reasonably good non-linear optical (NLO) behavior. The intramolecular contacts have been interpreted using natural bond orbital (NBO) and natural localized molecular orbital (NLMO) analysis.

  2. Doxofylline and Theophylline: A Comparative Clinical Study

    PubMed Central

    Akram, MD Faiz; Nasiruddin, Mohammad; Ahmad, Zuber; Ali Khan, Rahat

    2012-01-01

    Objectives COPD is one of the major public health problems worldwide. Theophylline has been used in the treatment of COPD for decades. Doxofylline a new theophylline congener has been claimed to have better safety profile. The study was undertaken to compare theophylline and doxophylline at doses recommended and commonly used in clinical practice. Methods The study was conducted in patients of COPD in TB chest department of a medical college hospital. It was randomized, prospective and open label. A total of 154 patients were divided in two group .Group I was administered 400 mg theophylline SR once daily and group II was administered doxofylline 400 mg twice a day orally. Spirometric variables symptom score, and adverse effects were recorded on day 0, 7 and 21 of therapy. Data were compared and analysed using SPSS version 16. Results Results of the study showed that there was no statistically significant difference with respect to spirometric variables and symptom score in the two groups and there was no significant difference in two groups with respect to side effects (p>0.05). Conclusions It is concluded that doxophylline has no advantage over theophylline in terms of either efficacy or safety on the doses commonly used in current clinical practice. PMID:23373027

  3. Comparative study of INPIStron and spark gap

    NASA Technical Reports Server (NTRS)

    Han, Kwang S.; Lee, Ja H.

    1993-01-01

    An inverse pinch plasma switch, INPIStron, was studied in comparison to a conventional spark gap. The INPIStron is under development for high power switching applications. The INPIStron has an inverse pinch dynamics, opposed to Z-pinch dynamics in the spark gap. The electrical, plasma dynamics and radiative properties of the closing plasmas have been studied. Recently the high-voltage pulse transfer capabilities or both the INPIStron and the spark gap were also compared. The INPIStron with a low impedance Z = 9 ohms transfers 87 percent of an input pulse with a halfwidth of 2 mu s. For the same input pulse the spark gap of Z = 100 ohms transfers 68 percent. Fast framing and streak photography, taken with an TRW image converter camera, was used to observe the discharge uniformity and closing plasma speed in both switches. In order to assess the effects of closing plasmas on erosion of electrode material, emission spectra of two switches were studied with a spectrometer-optical multi channel analyzer (OMA) system. The typical emission spectra of the closing plasmas in the INPIStron and the spark gap showed that there were comparatively weak carbon line emission in 658.7 nm and copper (electrode material) line emissions in the INPIStron, indicating low erosion of materials in the INPIStron.

  4. EFQPSK Versus CERN: A Comparative Study

    NASA Technical Reports Server (NTRS)

    Borah, Deva K.; Horan, Stephen

    2001-01-01

    This report presents a comparative study on Enhanced Feher's Quadrature Phase Shift Keying (EFQPSK) and Constrained Envelope Root Nyquist (CERN) techniques. These two techniques have been developed in recent times to provide high spectral and power efficiencies under nonlinear amplifier environment. The purpose of this study is to gain insights into these techniques and to help system planners and designers with an appropriate set of guidelines for using these techniques. The comparative study presented in this report relies on effective simulation models and procedures. Therefore, a significant part of this report is devoted to understanding the mathematical and simulation models of the techniques and their set-up procedures. In particular, mathematical models of EFQPSK and CERN, effects of the sampling rate in discrete time signal representation, and modeling of nonlinear amplifiers and predistorters have been considered in detail. The results of this study show that both EFQPSK and CERN signals provide spectrally efficient communications compared to filtered conventional linear modulation techniques when a nonlinear power amplifier is used. However, there are important differences. The spectral efficiency of CERN signals, with a small amount of input backoff, is significantly better than that of EFQPSK signals if the nonlinear amplifier is an ideal clipper. However, to achieve such spectral efficiencies with a practical nonlinear amplifier, CERN processing requires a predistorter which effectively translates the amplifier's characteristics close to those of an ideal clipper. Thus, the spectral performance of CERN signals strongly depends on the predistorter. EFQPSK signals, on the other hand, do not need such predistorters since their spectra are almost unaffected by the nonlinear amplifier, Ibis report discusses several receiver structures for EFQPSK signals. It is observed that optimal receiver structures can be realized for both coded and uncoded EFQPSK

  5. A Comparative Study of Mammalian Diversification Pattern

    PubMed Central

    Yu, Wenhua; Xu, Junxiao; Wu, Yi; Yang, Guang

    2012-01-01

    Although mammals have long been regarded as a successful radiation, the diversification pattern among the clades is still poorly known. Higher-level phylogenies are conflicting and comprehensive comparative analyses are still lacking. Using a recently published supermatrix encompassing nearly all extant mammalian families and a novel comparative likelihood approach (MEDUSA), the diversification pattern of mammalian groups was examined. Both order- and family-level phylogenetic analyses revealed the rapid radiation of Boreoeutheria and Euaustralidelphia in the early mammalian history. The observation of a diversification burst within Boreoeutheria at approximately 100 My supports the Long Fuse model in elucidating placental diversification progress, and the rapid radiation of Euaustralidelphia suggests an important role of biogeographic dispersal events in triggering early Australian marsupial rapid radiation. Diversification analyses based on family-level diversity tree revealed seven additional clades with exceptional diversification rate shifts, six of which represent accelerations in net diversification rate as compared to the background pattern. The shifts gave origin to the clades Muridae+Cricetidae, Bovidae+Moschidae+Cervidae, Simiiformes, Echimyidae, Odontoceti (excluding Physeteridae+Kogiidae+Platanistidae), Macropodidae, and Vespertilionidae. Moderate to high extinction rates from background and boreoeutherian diversification patterns indicate the important role of turnovers in shaping the heterogeneous taxonomic richness observed among extant mammalian groups. Furthermore, the present results emphasize the key role of extinction on erasing unusual diversification signals, and suggest that further studies are needed to clarify the historical radiation of some mammalian groups for which MEDUSA did not detect exceptional diversification rates. PMID:22457604

  6. Comparative Study of Vented vs. Unvented Crawlspaces

    SciTech Connect

    Biswas, Kaushik; Christian, Jeffrey E; Gehl, Anthony C

    2011-10-01

    There has been a significant amount of research in the area of building energy efficiency and durability. However, well-documented quantitative information on the impact of crawlspaces on the performance of residential structures is lacking. The objective of this study was to evaluate and compare the effects of two crawlspace strategies on the whole-house performance of a pair of houses in a mixed humid climate. These houses were built with advanced envelope systems to provide energy savings of 50% or more compared to traditional 2010 new construction. One crawlspace contains insulated walls and is sealed and semi-conditioned. The other is a traditional vented crawlspace with insulation in the crawlspace ceiling. The vented (traditional) crawlspace contains fiberglass batts installed in the floor chase cavities above the crawl, while the sealed and insulated crawlspace contains foil-faced polyisocyanurate foam insulation on the interior side of the masonry walls. Various sensors to measure temperatures, heat flux through crawlspace walls and ceiling, and relative humidity were installed in the two crawlspaces. Data from these sensors have been analyzed to compare the performance of the two crawlspace designs. The analysis results indicated that the sealed and insulated crawlspace design is better than the traditional vented crawlspace in the mixed humid climate.

  7. The experimental study on heat rejection equipment

    NASA Astrophysics Data System (ADS)

    Nakagawa, Toshihiko; Atsumi, Masahiro; Tokue, Rinzo

    1992-07-01

    This paper describes the concept study and the experimental work for development of the advanced style expendable heat rejection device. Emphasis is laid on minimizing the hardware weight and using innocuous coolant. Empirical heat transfer characteristics of water spray cooling were obtained and applied to the mathematical model to evaluate the performance. Besides the development of spray nozzle, prototype model of 4 kW class evaporator was fabricated and tested. Heat rejection rate of 3.2-4.5 kW was attained at both (high/low altitude) modes of operation, and feasibility of this heat rejection device was assured.

  8. Experimental Study of Nucleon Structure and QCD

    SciTech Connect

    Jian-Ping Chen

    2012-03-01

    Overview of Experimental Study of Nucleon Structure and QCD, with focus on the spin structure. Nucleon (spin) Structure provides valuable information on QCD dynamics. A decade of experiments from JLab yields these exciting results: (1) valence spin structure, duality; (2) spin sum rules and polarizabilities; (3) precision measurements of g{sub 2} - high-twist; and (4) first neutron transverse spin results - Collins/Sivers/A{sub LT}. There is a bright future as the 12 GeV Upgrade will greatly enhance our capability: (1) Precision determination of the valence quark spin structure flavor separation; and (2) Precision extraction of transversity/tensor charge/TMDs.

  9. Sequential Experimentation: Comparing Stochastic Approximation Methods Which Find the "Right" Value of the Independent Variable.

    ERIC Educational Resources Information Center

    Hummel, Thomas J.; Johnston, Charles B.

    This research investigates stochastic approximation procedures of the Robbins-Monro type. Following a brief introduction to sequential experimentation, attention is focused on formal methods for selecting successive values of a single independent variable. Empirical results obtained through computer simulation are used to compare several formal…

  10. Comparative study of heart sound localization algorithms

    NASA Astrophysics Data System (ADS)

    Moukadem, A.; Dieterlen, A.; Hueber, N.; Brandt, C.; Raymond, P.

    2011-05-01

    The purpose of this document is to present a comparative study of five algorithms of heart sound localization, one of which, is a method based on radial basis function networks applied in a novel approach. The advantages and disadvantages of each method are evaluated according to a data base of 50 subjects in which there are 25 healthy subjects selected from the University Hospital of Strasbourg (HUS) and from theMARS500 project (Moscow) and 25 subjects with cardiac pathologies selected from the HUS. This study is made under the control of an experienced cardiologist. The performance of each method is evaluated by calculating the area under a receiver operating curve (AUC) and the robustness is shown against different levels of additive white Gaussian noise.

  11. Intraosseous and intravenous administration of antibiotics yields comparable plasma concentrations during experimental septic shock

    PubMed Central

    Strandberg, G; Larsson, A; Lipcsey, M; Michalek, J; Eriksson, M

    2015-01-01

    Background We aimed to investigate whether comparable antibiotic concentrations could be reached with intraosseous and intravenous administration during septic shock. Methods In this randomized, prospective experimental study conducted at an animal research laboratory at the University Hospital of Uppsala, eight anesthetized pigs, weighing 21.2 to 29.1 kg (mean: 25.2 ± 2.3 kg), received endotoxin infusion at 4 μg/kg/h for 6 h. At the onset of clinical shock, alternatively after 3 h of endotoxemia, they received 75 mg/kg of cefotaxime and 7 mg/kg of gentamicin either in a proximal tibial intraosseous catheter or in a peripheral intravenous catheter. Mixed venous samples were taken after 5, 15, 30, 60, 120 and 180 min and analyzed for antibiotic concentrations. Results For both antibiotics, plasma concentrations after intraosseous and intravenous administration followed similar curves throughout the observation period, and peak concentrations were comparable. Mean concentration area under the curve (AUC mg × h/l) for cefotaxime was 108.1 ± 19.5 after intraosseous and 116.5 ± 11.1 after intravenous administration; ratio 0.93, (95% CI 0.71–1.19). Mean AUC for gentamicin was 28.1 ± 6.8 for intraosseous and 32.2 ± 3.5 for intravenous administration; ratio 0.87 (95% CI 0.62–1.19). Conclusions In this porcine septic shock model, intraosseous and intravenous administration of gentamicin and cefotaxime yielded comparable concentrations. In an emergency, intraosseous administration of these antibiotics may be considered in severe infections when venous access is difficult. PMID:25557933

  12. Experimental Study of Top Heat Mode Thermosyphon

    NASA Astrophysics Data System (ADS)

    Hirashima, Masao; Kimura, Kenichiro; Utsumi, Yoichi; Kimura, Kenichi; Negishi, Kanji

    The purpose of this study is to develop the top heat mode thermosyphon that is very attractive means, for example, to accumulate directly the summer solar energy into the underground soil for the winter season. In this case, it can exclude the complex piping and mechanical pump to circulate the hot water absorbed the solar energy through the piping system buried in the soil layer. The several ideas concerning the top heat thermosyphon had been proposed, however, there were few reports on the definite experiments. The authors have carried out the experimental study of the top heat mode thermosyphon, with a simple lifting pipe, which could draw the working liquid from the under condenser to the upper evaporator section. The improvement of the main construction parts such as evaporator, lifting pipe, liquid reservoir trap and vapour nozzle have been performed in the present experiment in order to obtain the optimum operation range.

  13. Experimental studies on coaxial vortex loops

    NASA Astrophysics Data System (ADS)

    Mariani, R.; Kontis, K.

    2010-12-01

    An experimental study has been conducted on the formation and propagation of coaxial vortex loops using a shock tube facility. The study aimed at evaluating the flow characteristics of pairs of corotating vortex rings that generate the leapfrogging phenomenon. The driver and driven gas of the shock tube were air. Three driver pressures were used (4, 8, and 12 bars) with the driven gas being at ambient conditions. The Mach numbers of the shock wave generated inside the shock tube were 1.34, 1.54, and 1.66, respectively. The sudden expansion present at the diaphragm location effectively decreased the Mach number value of the traveling shock wave. Results showed that a pair of vortex rings staggered with respect to time and with the same direction rotation lead to leapfrogging. Results also indicated that the number of leapfrogging occurrences is related to the Reynolds number of the vortex ring pairs with a decrease in leapfrogs at higher Reynolds numbers.

  14. A comparative study on monitored anesthesia care

    PubMed Central

    Sen, Jayashree; Sen, Bitan

    2014-01-01

    Aim: The aim of this study is to compare the effectiveness, hemodynamic changes and duration of sedation and analgesia between combinations of fortwin-phenergan-midazolam (FPM) and ketamine - midazolam (KM) along with local anesthesia for the surgeries done under the umbrella of monitored anesthesia care. Materials and Methods: A total of 50 patients undergoing surgeries as tympanoplasty, septoplasty, lip repair, dacrocystectomy and cataract under local anesthesia, randomly received either intravenous (IV) fortwin 0.3 mg/kg over 1 min followed by IV midazolam 0.04 mg/kg plus IV phenergan 12.5 mg (Group FPM) or IV ketamine 0.3 mg/kg over 1 min plus IV midazolam 0.04 mg/kg (Group KM). Sedation was titrated to Ramsay sedation score (RSS) of 3. Patients’ mean arterial pressure (MAP), heart rate (HR), saturation peripheral pulse, duration of sedation and need for intraoperative rescue sedation/analgesic were recorded and compared. Satisfaction of patients (using a 1-7 point Likert verbal rating scale) and readiness for discharge towards (time to Aldrete score of 10) were also determined. Result: Group KM had significant rise in HR (20-25%) and MAP (25-30%) from 30 min after the bolus dose given until the end of the surgery in contrast to Group FPM. The target sedation level (RSS ≥ 3) was higher in Group FPM (n = 23 [92%]) as compared with Group KM (n = 12 [48%]). Time until need for rescue sedation was 66.96 ± 17.19 min in FPM and 32.80 ± 8.90 min in KM group. The patient satisfaction (Likert scale) is more with the FPM group (6.12 ± 0.83 vs. 4.40 ± 1.20). Conclusion: We found that the combination of FPM is superior to the KM combination as per the hemodynamic changes, duration of analgesia, patients’ satisfaction and efficacy of the drugs are concerned. PMID:25886327

  15. Computational and experimental study of laminar flames

    SciTech Connect

    Smooke, Mitchell

    2015-05-29

    During the past three years, our research has centered on an investigation of the effects of complex chemistry and detailed transport on the structure and extinction of hydrocarbon flames in coflowing axisymmetric configurations. We have pursued both computational and experimental aspects of the research in parallel on both steady-state and time-dependent systems. The computational work has focused on the application of accurate and efficient numerical methods for the solution of the steady-state and time-dependent boundary value problems describing the various reacting systems. Detailed experimental measurements were performed on axisymmetric coflow flames using two-dimensional imaging techniques. Previously, spontaneous Raman scattering, chemiluminescence, and laser-induced fluorescence were used to measure the temperature, major and minor species profiles. Particle image velocimetry (PIV) has been used to investigate velocity distributions and for calibration of time-varying flames. Laser-induced incandescence (LII) with an extinction calibration was used to determine soot volume fractions, while soot surface temperatures were measured with three-color optical pyrometry using a color digital camera. A blackbody calibration of the camera allows for determination of soot volume fraction as well, which can be compared with the LII measurements. More recently, we have concentrated on a detailed characterization of soot using a variety of techniques including time-resolved LII (TiRe-LII) for soot primary particles sizes, multi-angle light scattering (MALS) for soot radius of gyration, and spectrally-resolved line of sight attenuation (spec-LOSA). Combining the information from all of these soot measurements can be used to determine the soot optical properties, which are observed to vary significantly depending on spatial location and fuel dilution. Our goal has been to obtain a more fundamental understanding of the important fluid dynamic and chemical interactions in

  16. Water Ice in Comets: A Comparative Study

    NASA Astrophysics Data System (ADS)

    Protopapa, Silvia; Sunshine, J.; Feaga, L. M.; Kelley, M. S.; A'Hearn, M. F.; Farnham, T.; DIXI Team

    2013-06-01

    Processes involving the sublimation of volatiles dominate cometary activity and drive the release of ancient material from within the nucleus into the coma. As comets are kept cold for most of their history, they contain the least processed primordial materials that accumulated into the giant planets. In addition, comets may have delivered their ices and organics to the primitive Earth. The Deep Impact eXtended Investigation (DIXI) to comet Hartley 2 revealed a highly active comet with bright icy-rich jets. We present a detailed characterization of the composition and texture of the ices and refractories in the inner-most coma of Hartley 2, closer than a few kilometers from the surface. This analysis is conducted using laboratory measurements of optical constants of cometary analog materials. We also discuss the implications of these findings on the accretion process that led to the formation of cometary nuclei and therefore of planets. The physical makeup of the ice grains in comet Hartley 2 is compared with that of water ice in the interior, surface, and coma of other comets (e.g., 9P/Tempel 1, C/2002 T7 (LINEAR), 17P/Holmes). Through this comparative study, we investigate how ice is redistributed from the interior to the surface and ultimately into the coma of comets.

  17. Comparative Cognitive Task Analyses of Experimental Science and Instructional Laboratory Courses

    NASA Astrophysics Data System (ADS)

    Wieman, Carl

    2015-09-01

    Undergraduate instructional labs in physics generate intense opinions. Their advocates are passionate as to their importance for teaching physics as an experimental activity and providing "hands-on" learning experiences, while their detractors (often but not entirely students) offer harsh criticisms that they are pointless, confusing and unsatisfying, and "cookbook." Here, both to help understand the reason for such discrepant views and to aid in the design of instructional lab courses, I compare the mental tasks or types of thinking ("cognitive task analysis") associated with a physicist doing tabletop experimental research with the cognitive tasks of students in an introductory physics instructional lab involving traditional verification/confirmation exercises.

  18. Comparative Study of Airfoil Flow Separation Criteria

    NASA Astrophysics Data System (ADS)

    Laws, Nick; Kahouli, Waad; Epps, Brenden

    2015-11-01

    Airfoil flow separation impacts a multitude of applications including turbomachinery, wind turbines, and bio-inspired micro-aerial vehicles. In order to achieve maximum performance, some devices operate near the edge of flow separation, and others use dynamic flow separation advantageously. Numerous criteria exist for predicting the onset of airfoil flow separation. This talk presents a comparative study of a number of such criteria, with emphasis paid to speed and accuracy of the calculations. We evaluate the criteria using a two-dimensional unsteady vortex lattice method, which allows for rapid analysis (on the order of seconds instead of days for a full Navier-Stokes solution) and design of optimal airfoil geometry and kinematics. Furthermore, dynamic analyses permit evaluation of dynamic stall conditions for enhanced lift via leading edge vortex shedding, commonly present in small flapping-wing flyers such as the bumblebee and hummingbird.

  19. Comparative microscopy study of Vibrio cholerae flagella

    NASA Astrophysics Data System (ADS)

    Konnov, Nikolai P.; Baiburin, Vil B.; Zadnova, Svetlana P.; Volkov, Uryi P.

    1999-06-01

    A fine structure of bacteria flagella is an important problem of molecular cell biology. Bacteria flagella are the self-assembled structures that allow to use the flagellum protein in a number of biotechnological applications. However, at present, there is a little information about high resolution scanning probe microscopy study of flagellum structure, in particular, about investigation of Vibrio cholerae flagella. In our lab have been carried out the high resolution comparative investigation of V. cholerae flagella by means of various microscopes: tunneling (STM), scanning force (SFM) and electron transmission. As a scanning probe microscope is used designed in our lab versatile SPM with replaceable measuring heads. Bacteria were grown, fixed and treated according to the conventional techniques. For STM investigations samples were covered with Pt/Ir thin films by rotated vacuum evaporation, in SFM investigations were used uncovered samples. Electron microscopy of the negatively stained bacteria was used as a test procedure.

  20. Supracostal percutaneous nephrolithotomy: A prospective comparative study

    PubMed Central

    Sinha, Maneesh; Krishnappa, Pramod; Subudhi, Santosh Kumar; Krishnamoorthy, Venkatesh

    2016-01-01

    Introduction: A widely prevalent fear of thoracic complications with the supracostal approach has led to its underutilization in percutaneous nephrolithotomy (PCNL). We frequently use the supracostal approach and compared the efficacy and thoracic complications of infracostal, supra 12th, and supra 11th punctures. Materials and Methods: This was a prospective study of patients who underwent PCNL between January 2005 and December 2012. The patients were divided into three groups based on the access: infracostal, supra 12th (between the 11th and 12th ribs) and supra 11th (between the 10th and 11th ribs). Clearance rates, fall in hemoglobin levels, transfusion rates, perioperative analgesic requirements, hospital stay and thoracic complications were compared. Results: Seven hundred patients were included for analysis. There were 179 (25.5%) patients in the supra 11th group, 187 (26.7%) patients in the supra 12th group and 334 (47.8%) patients in the infracostal group. The overall clearance rate was 78% with no difference in the three groups. The postoperative analgesic requirements were significantly higher in the supracostal groups and showed a graded increase from infracostal to supra 12th to supra 11th. During the study period, only 2 patients required angioembolization (0.3%) and none required open exploration. The number of patients requiring intercostal chest drain insertion was extremely low, at 1.6% and 2.2% in the supra 12th and supra 11th groups, respectively. Conclusions: Our results confirm the feasibility of the supracostal approach including punctures above the 11th rib, albeit at the cost of an increase in thoracic complications. Staying in the line of the calyx has helped us to minimize the most dreaded complication of bleeding requiring angioembolization. PMID:26941494

  1. [Chemoprophylaxis of secondary peritoneal hydatidosis. Experimental study].

    PubMed

    Errasti Alustiza, J; Arévalo Alonso, J M; Ortiz Tudanca, J; Rebollar Saenz, J; Martínez Blázquez, C; Vítores López, J M

    1993-09-01

    We have studied the effectiveness of pharmacologic prophylaxis of experimental peritoneal hydatidosis. Mice (n = 140, divided in ten groups) suffered intraperitoneal contamination with protoscoleces of E. granulosus from sheep. Each group received different treatment (mebendazole, praziquantel, or both), in three different schedules (during 3 days before contamination, during 7 days after contamination, or both before and after Mebendazole 150 mg/kg-day), praziquantel (25 mg/kg-day) were given in three daily doses. Mice were sacrificed six months later and the number and type of existing peritoneal cysts was recorded. Prophylaxis prior to contamination was shown ineffective. Early treatment greatly decreased the severity of the peritoneal hydatidosis. The administration of the drug before and after contamination, did not improve the results obtained when the drug was given after contamination. Both mebendazole and praziquantel were effective, though the former obtained better results. The association of both drugs does not improve the results obtained with mebendazole alone. These experimental results recommend the early use of mebendazol or praziquantel after open surgery for hydatidosis, in order to prevent the occurrence of secondary peritoneal hydatidosis. PMID:8217380

  2. Experimental and theoretical studies in nonlinear aeroelasticity

    NASA Astrophysics Data System (ADS)

    Attar, Peter Joseph

    Experimental and theoretical studies are conducted in the field of nonlinear aeroelasticity. Specifically two aeroelastic configurations, a flapping flag and a delta wing, are investigated and correlations between theory and experiment are presented. Two nonlinear structural theories are used to describe the structural behavior of the two models which are studied. The delta wing structural behavior is modeled using the nonlinear plate theory of von Karman. The nonlinearity in this model is due to the coupling between the out-of-plane and in-plane deflections and the model allows for moderately large out-of-plane plate deflections. The flapping flag structural model is a nonlinear beam theory which includes nonlinearities due to both large curvature and inertia. The axial deflection in this model is related to the out-of-plane deflection using an axially inextensible theory. The aerodynamic theory used is potential flow theory, which is applicable to low speed flows. The equation which describes potential flow is the Laplace equation, which is a linear partial differential equation. The Laplace equation is solved using a vortex lattice method. Aeroelastic solutions are found using both the classic small disturbance linearized fluid-structure interface boundary condition and the exact nonlinear boundary condition. The aeroelastic model which includes the nonlinear boundary conditions also includes a free wake solution. Several reduced order methods are explored. Normal mode solutions, both for the structural and aerodynamic models, are studied along with a proper orthogonal decomposition model for the aerodynamic flow. A brief description of a parallel implementation of the aeroelastic simulation code is also given and the parallel speedup is shown to be nearly linear for a certain class of problems. Correlation between theory and experiment is presented for both the delta wing and flapping flag model. Several steady angle of attack cases were investigated for the

  3. Comparing comparators: a look at control arms in kidney cancer studies over the years.

    PubMed

    Bracarda, S; Porta, C; Sisani, M; Marrocolo, F; Paglino, C; Hamzaj, A; D Buono, S; Sternberg, C N

    2015-01-01

    In the past decade, an increasing number of frequently positive randomised clinical trials have been completed, allowing new consideration of the present therapeutic armamentarium for advanced renal cell carcinoma. These studies were predominantly designed to compare the experimental drugs with 1 of 2 active control arms: interferon alpha-2a or sorafenib. Different from expectations, the final results of some of these studies were not in line with the predictions, and the reasons have not been fully investigated. Consequently, there is a great need for careful analysis of the studies carried out so far, chiefly the role and validity of the control arms. In this regard, the examination of patient baseline characteristics and other factors of potential interest seems fundamental for a correct analysis of the results of these trials and consequent optimal use of the available targeted agents. PMID:25375270

  4. Free will and consciousness: experimental studies.

    PubMed

    Shepherd, Joshua

    2012-06-01

    What are the folk-conceptual connections between free will and consciousness? In this paper I present results which indicate that consciousness plays central roles in folk conceptions of free will. When conscious states cause behavior, people tend to judge that the agent acted freely. And when unconscious states cause behavior, people tend to judge that the agent did not act freely. Further, these studies contribute to recent experimental work on folk philosophical affiliation, which analyzes folk responses to determine whether folk views are consistent with the view that free will and determinism are incompatible (incompatibilism) or with the opposite view (compatibilism). Conscious causation of behavior tends to elicit pro-free will judgments, even when the causation takes place deterministically. Thus, when controlling for consciousness, many folk seem to be compatibilists. However, participants who disagree with the deterministic or cognitive scientific descriptions given of human behavior tend to give incompatibilist responses. PMID:22480780

  5. Experimental study of crossing angle collision

    SciTech Connect

    Chen, T.; Rice, D.; Rubin, D.; Sagan, D.; Tigner, M.

    1993-05-01

    The non-linear coupling due to the beam-beam interaction with crossing angle has been studied. The major effect of a small ({approximately}12mrad) crossing angle is to excite 5Q{sub x}{plus_minus}Q{sub s}=integer coupling resonance family on large amplitude particles, which results in bad lifetime. On the CESR, a small crossing angle ({approximately}2.4mr) was created at the IP and a reasonable beam-beam tune-shift was achieved. The decay rate of the beam is measured as a function of horizontal tune with and without crossing angle. The theoretical analysis, simulation and experimental measurements have a good agreement. The resonance strength as a function of crossing angle is also measured.

  6. Experimental Studies in Helicopter Vertical Climb Performance

    NASA Technical Reports Server (NTRS)

    McKillip, Robert M., Jr.

    1996-01-01

    Data and analysis from an experimental program to measure vertical climb performance on an eight-foot model rotor are presented. The rotor testing was performed using a unique moving-model facility capable of accurately simulating the flow conditions during axial flight, and was conducted from July 9, 1992 to July 16, 1992 at the Dynamic Model Track, or 'Long Track,' just prior to its demolition in August of 1992. Data collected during this brief test program included force and moment time histories from a sting-mounted strain gauge balance, support carriage velocity, and rotor rpm pulses. In addition, limited video footage (of marginal use) was recorded from smoke flow studies for both simulated vertical climb and descent trajectories. Analytical comparisons with these data include a series of progressively more detailed calculations ranging from simple momentum theory, a prescribed wake method, and a free-wake prediction.

  7. Comparative study of pressure-flow parameters.

    PubMed

    Eri, Lars M; Wessel, Nicolai; Tysland, Ole; Berge, Viktor

    2002-01-01

    Methods for quantification of bladder outlet obstruction (BOO) are still controversial. Parameters such as detrusor opening pressure (p(det.open)), maximum detrusor pressure (p(det.max)), minimum voiding pressure (p(det.min.void)), and detrusor pressure at maximum flow rate (P(det.Qmax)) separate obstructed from nonobstructed patients to some extent, but two nomograms, the Abrams-Griffiths nomogram and the linearized passive urethral resistance relation (LinPURR), are more accepted for this purpose, along with the urethral resistance algorithm. In this retrospective, methodologic study, we evaluated the properties of these parameters with regard to test-retest reproducibility and ability to detect a moderate (pharmacologic) and a pronounced (surgical) relief of bladder outlet obstruction. We studied the pressure-flow charts of 42 patients who underwent 24 weeks of androgen suppressive therapy, 42 corresponding patients who received placebo, and 30 patients who had prostate surgery. The patients performed repeat void pressure-flow examinations before and after treatment or placebo. The various parameters were compared. Among the bladder pressure parameters, P(det.Qmax) seemed to have some advantages, supporting the belief that it is the most relevant detrusor pressure parameter to include in nomograms to quantify BOO. In assessment of a large decrease in urethral resistance, such as after TURp, resistance parameters that are based on maximum flow rate as well as detrusor pressure are preferable. PMID:11948710

  8. A comparative study of depot injection techniques.

    PubMed

    Quartermaine, S; Taylor, R

    Depot injections of long-acting neuroleptic drugs, by maintaining a consistent drug regime, together with regular contact with health-care professionals, are an important factor in helping psychiatric patients who live in the community. As these injections are administered over a long period--often for years--it is important that care is taken to minimise discomfort and to reduce the incidence of problems at the injection site. Seepage of even small amounts of the medication will result in an inaccurate dose being absorbed and, owing to the irritant nature of many of these drugs, leakage into subcutaneous tissue and on to the skin surface can cause pain, irritation and lesions. This study was set up to compare two techniques of administering deep intramuscular injections to determine which best fulfilled the criteria of preventing seepage while causing as little discomfort as possible. The two methods used were the Z-track, which is standard practice in the UK, and the air bubble, which is widely taught and used in Canada and the USA. The study showed the air-bubble method to be significantly more effective at controlling seepage than the Z-track. PMID:7644369

  9. Experimental study of low Reynolds number nozzles

    NASA Technical Reports Server (NTRS)

    Grisnik, Stanley P.; Smith, Tamara A.; Saltz, Larry E.

    1987-01-01

    High-performance electrothermal thrusters operate in a low nozzle-throat Reynolds number regime. Under these conditions, the flow boundary layer occupies a large volume inside the nozzle, contributing to large viscous losses. Four nozzles (conical, bell, trumpet, and modified trumpet) and a sharp-edged orifice were evaluated over a Reynolds number range of 500 to 9000 with unheated nitrogen and hydrogen. The nozzles showed significant decreases in specific impulse efficiency with decreasing Reynolds number. At Reynolds numbers less than 1000, all four nozzles were probably filled with a large boundary layer. The discharge coefficient decreased with Reynolds number in the same manner as the specific impulse efficiency. The bell and modified trumpet nozzles had discharge coefficients 4 to 8 percent higher than those of the cone or trumpet nozzles. The Two-Dimensional Kinetics (TDK) nozzle analysis computer program was used to predict nozzle performance. The results were then compared to the experimental results in order to determine the accuracy of the program within this flow regime.

  10. Experimental study of asymmetric heart valve prototype

    NASA Astrophysics Data System (ADS)

    Vukicevic, M.; Fortini, S.; Querzoli, G.; Cenedese, A.; Pedrizzetti, G.

    2011-11-01

    The mechanical heart valves (MHVs) are extremely important medical devices, commonly used for diseased heart valves replacement. Despite the long term of use and constant design refinement, the MHVs are very far from ideal and their performance is very diverse from that of the native ones. It has been approved that small variations in geometry of valvular leaflets influence the significant change in the intraventricular vortical flow, known as one of the most important factors for the overall functionality of the heart. We have experimentally examined the home-made heart valve prototypes, exclusively modeled for the mitral valve replacement. The performance and energetic properties of the prototypes have been compared with those in the presence of standard MHVs. The analysis was based on the testing of intraventricular fluid dynamics, usually missing criteria for the quality of the valve performance. It has been shown that the asymmetric prototype, with unequal leaflets and D-shaped orifice produces flow patterns and energetic properties close to those found in the healthy subjects. Thus, the break of symmetry in the standard bi-leaflet MHV prosthesis, at least from the fluid dynamics point of view, is worthwhile to be considered for the design of MHVs for the mitral valve replacement.

  11. Experimental study of solar simulator mirror cryocontamination

    NASA Technical Reports Server (NTRS)

    Galjaev, V. L.; Makarov, A. A.; Afanassiev, N. A.

    1994-01-01

    The background and tasks formulation of the study of Solar Simulator collimation mirror cryocontamination in Large Thermal Vacuum Facility are outlined, research methods and experiment procedures are described, experimental relationships obtained are analyzed and practical recommendations are given. The accepted procedure of thermal vacuum tests as a rule defines the sequence of operations for verifying the spacecraft under test without taking into account measures for preventing Solar Simulator collimation mirror contamination and degradation. On the other hand, evacuation procedures is defined for conditions of achieving the required vacuum in the shortest possible time with using the available evacuation equipment at a regime close to the optimum one. Similarly, cryopanel cooling down cyclogram and test object preparation process are not analyzed from the viewpoint of ways of reducing environmental detrimental effects on thermal vacuum facility contamination-sensitive systems. Solar Simulator mirror contamination and its reflective characteristics change results in degradation of solar flux parameters and reduction of simulator continuous operation time. Methods of consideration of optical effects due to mirror surface contamination are actually missing. The effects themselves are not quite understood and data cited in literature as a rule, were obtained under conditions different from real thermal vacuum facility and therefore should be subjected to additional experimental verification. Only in the last few years contamination effect on optical surfaces degradation has been considered with using empirical relations. Mirror reflective properties degradation leads to the increase of Solar Simulator errors. This ultimately has an adverse effect on S/C ground development, schedule and cost of thermal vacuum tests. Besides, the mirror maintenance in operable state becomes more expensive. The present paper is dedicated to the study of Solar Simulator collimation

  12. Towards better modeling of chitosan nanoparticles production: screening different factors and comparing two experimental designs.

    PubMed

    Abdel-Hafez, Salma M; Hathout, Rania M; Sammour, Omaima A

    2014-03-01

    The aim of this study is to utilize statistical designs and mathematical modeling to end the continuous debate about the different variables that influence the production of nanoparticles using the ionic gelation method between the biopolymer chitosan (CS) and tripolyphosphate (TPP) ion. Preliminary experiments were adopted to extract the optimum conditions for the nanoparticles preparation and model construction. Critical process parameters were screened using the one-factor-at-a-time (OFAT) approach to select optimum experimental regions. Finally, these factors were optimized using two different methods of response surface modeling; the Box-Behnken and the D-optimal. The significant models showed excellent fitting of the data. The two methods were validated using a set of check points and were subsequently compared. Good agreement between actual and predicted values was obtained though the D-optimal model was more successful in predicting the particle size of the prepared nanoparticles with percentage bias as small as 1.49%. Nanoparticles were produced with diameters ranging from 52.21 nm to 400.30 nm, particle polydispersity from 0.06 to 0.40 and suitable morphology. This work provides an overview on the production of chitosan nanoparticles with desirable size enabling their successful use in drugs delivery and targeting or in any nanotechnology or interfacial application. PMID:24355618

  13. Experimental and numerical study on condensation in transonic steam flow

    NASA Astrophysics Data System (ADS)

    Majkut, Mirosław; Dykas, Sławomir; Strozik, Michał; Smołka, Krystian

    2015-09-01

    The present paper describes an experimental and numerical study of steam condensing flow in a linear cascade of turbine stator blades. The experimental research was performed on the facility of a small scale steam power plant located at Silesian University of Technology in Gliwice, Poland. The test rig of the facility allows us to perform the tests of steam transonic flows for the conditions corresponding to these which prevail in the low-pressure (LP) condensing steam turbine stages. The experimental data of steam condensing flow through the blade-to- blade stator channel were compared with numerical results obtained using the in-house CFD numerical code TraCoFlow. Obtained results confirmed a good quality of the performed experiment and numerical calculations.

  14. Mechanical properties of jennite: A theoretical and experimental study

    SciTech Connect

    Moon, Juhyuk; Yoon, Seyoon; Monteiro, Paulo J.M.

    2015-05-15

    The objective of this study is to determine the mechanical properties of jennite. To date, several hypotheses have been proposed to predict the structural properties of jennite. For the first time as reported herein, the isothermal bulk modulus of jennite was measured experimentally. Synchrotron-based high-pressure x-ray diffraction experiments were performed to observe the variation of lattice parameters under pressure. First-principles calculations were applied to compare with the experimental results and predict additional structural properties. Accurately measured isothermal bulk modulus herein (K{sub 0} = 64(2) GPa) and the statistical assessment on experimental and theoretical results suggest reliable mechanical properties of shear and Young's modulus, Poisson's ratio, and elastic tensor coefficients. Determination of these fundamental structural properties is the first step toward greater understanding of calcium–silicate–hydrate, as well as provides a sound foundation for forthcoming atomic level simulations.

  15. Experimental Study of RF Pulsed Heating

    SciTech Connect

    Laurent, Lisa; Tantawi, Sami; Dolgashev, Valery; Nantista, Christopher; Higashi, Yasuo; Aicheler, Markus; Heikkinen, Samuli; Wuensch, Walter; /CERN

    2011-11-04

    Cyclic thermal stresses produced by rf pulsed heating can be the limiting factor on the attainable reliable gradients for room temperature linear accelerators. This is especially true for structures that have complicated features for wakefield damping. These limits could be pushed higher by using special types of copper, copper alloys, or other conducting metals in constructing partial or complete accelerator structures. Here we present an experimental study aimed at determining the potential of these materials for tolerating cyclic thermal fatigue due to rf magnetic fields. A special cavity that has no electric field on the surface was employed in these studies. The cavity shape concentrates the magnetic field on one flat surface where the test material is placed. The materials tested in this study have included oxygen free electronic grade copper, copper zirconium, copper chromium, hot isostatically pressed copper, single crystal copper, electroplated copper, Glidcop(reg. sign), copper silver, and silver plated copper. The samples were exposed to different machining and heat treatment processes prior to rf processing. Each sample was tested to a peak pulsed heating temperature of approximately 110 C and remained at this temperature for approximately 10 x 10{sup 6} rf pulses. In general, the results showed the possibility of pushing the gradient limits due to pulsed heating fatigue by the use of copper zirconium and copper chromium alloys.

  16. Periodontal files--a comparative study.

    PubMed

    Pasquini, R; Clark, S M; Baradaran, S; Adams, D F

    1995-12-01

    Periodontal files are used by many dentists for instrumentation of root surfaces as a part of periodontal treatment. The purposes of this study were: 1) to examine, evaluate, and compare several periodontal files in 3 different conditions: new, used, and used/sharpened and 2) to evaluate the efficacy of 5 sharpening devices. The main characteristics observed included: the number, shape, and interval of blades; the active, rake, and lip angles; changes induced by wear; the influence of sharpening; and the type of metal surfaces comprising the blades. There was a wide range of active angles on each individual file, from a high of 75 degrees to a low of 51 degrees. The range of active angles for all blades on all new files was even greater, from a high of 87 degrees to a low of 30 degrees. Wear, observed on some but not all blades, was not extensive and appeared either as abrasion or, occasionally, as fracture of the blade edge. Sharpness scores (5 = sharpest and 1 = dullest) for new file blades were also extremely variable and spanned the full range of values, with a majority of blades scoring 3.5 and below. Attempts to sharpen files with several devices produced inconsistent results. All 5 sharpening devices had significant shortcomings. It was concluded that the extreme ranges both in active angles and in sharpness scores probably have a significant influence on effectiveness of root instrumentation. PMID:8683416

  17. Assays for mammalian tyrosinase: a comparative study

    SciTech Connect

    Jara, J.R.; Solano, F.; Lozano, J.A.

    1988-01-01

    This work describes a comparative study of the tyrosinase activity determined using three methods which are the most extensively employed; two radiometric assays using L-tyrosine as substrate (tyrosine hydroxylase and melanin formation activities) and one spectrophotometric assay using L-dopa (dopa oxidase activity). The three methods were simultaneously employed to measure the activities of the soluble, melanosomal, and microsomal tyrosinase isozymes from Harding-Passey mouse melanoma through their purification processes. The aim of this study was to find any correlation among the tyrosinase activities measured by the three different assays and to determine whether that correlation varied with the isozyme and its degree of purification. The results show that mammalian tyrosinase has a greater turnover number for L-dopa than for L-tyrosine. Thus, enzyme activity, expressed as mumol of substrate transformed per min, is higher in assays using L-dopa as substrate than those using L-tyrosine. Moreover, the percentage of hydroxylated L-tyrosine that is converted into melanin is low and is affected by several factors, apparently decreasing the tyrosinase activity measured by the melanin formation assay. Bearing these considerations in mind, average interassay factors are proposed. Their values are 10 to transform melanin formation into tyrosine hydroxylase activity, 100 to transform tyrosine hydroxylase into dopa oxidase activity, and 1,000 to transform melanin formation into dopa oxidase activity. Variations in these values due to the presence in the tyrosinase preparations of either inhibitors or regulatory factors in melanogenesis independent of tyrosinase are also discussed.

  18. Experimental study of ocean-atmosphere exchanges

    SciTech Connect

    Eymard, L.; Weill, A.; Planton, S.

    1994-12-31

    The SOFIA/ASTEX and SEMAPHORE campaigns were performed over open ocean, near the Azores, to study the ocean-atmosphere exchanges at the local and meso-scales, with a particular insight to the spatial variability of fluxes and related processes. In both cases, the experimental strategy involved two research aircraft and an oceanographic vessel, as well as surface buoys. SOFIA/ASTEX was more particularly devoted to the study of boundary layer and cloud properties, including microphysical and radiative aspects, in the framework of the international campaign ASTEX. SEMAPHORE was aimed at the analysis of surface fluxes and interactions with the upper ocean at the mesoscale. It included an important network of ocean circulation and thermal properties, from ships, current meter moorings, current drifters, and drifting buoys. The thermal front associated with the Azores current is an important feature of the ocean circulation and was particularly investigated. The analysis of data from meteorological satellites is also an important aspect of the two campaigns.

  19. Experimental Study of Lift-Generated Vortices

    NASA Technical Reports Server (NTRS)

    Rossow, Vernon J.; Nixon, David (Technical Monitor)

    1998-01-01

    The flow fields of vortices, whether bouyancy-driven or lift-generated, are fascinating fluid-dynamic phenomena which often possess intense swirl velocities and complex time-dependent behavior. As part of the on-going study of vortex behavior, this paper presents a historical overview of the research conducted on the structure and modification of the vortices generated by the lifting surfaces of subsonic transport aircraft. It is pointed out that the characteristics of lift-generated vortices are related to the aerodynamic shapes that produce them and that various arrangements of surfaces can be used to produce different vortex structures. The primary purpose of the research to be described is to find a way to reduce the hazard potential of lift-generated vortices shed by subsonic transport aircraft in the vicinity of airports during landing and takeoff operations. It is stressed that lift-generated vortex wakes are so complex that progress towards a solution requires application of a combined theoretical and experimental research program because either alone often leads to incorrect conclusions. It is concluded that a satisfactory aerodynamic solution to the wake-vortex problem at airports has not yet been found but a reduction in the impact of the wake-vortex hazard on airport capacity may become available in the foreseeable future through wake-vortex avoidance concepts currently under study. The material to be presented in this overview is drawn from aerospace journals that are available publicly.

  20. Theoretical and Experimental Studies of Radiative Shocks

    NASA Astrophysics Data System (ADS)

    Michaut, C.; Vinci, T.; Boireau, L.; Koenig, M.; Bouquet, S.; Benuzzi-Mounaix, A.; Osaki, N.; Herpe, G.; Falize, E.; Loupias, B.; Atzeni, S.

    2007-01-01

    This paper deals with the radiative shock from both theoretical and numerical points of view. It is based on the whole experimental results obtained at Laboratoire d'Utilisation des Lasers Intenses (LULI, École Polytechnique). Radiative shocks are high-Mach number shocks with a strong coupling between radiation and hydrodynamics which leads to a structure governed by a radiative precursor. These shocks are involved in various astrophysical systems: stellar accretion shocks, pulsating stars, interaction between supernovae and the interstellar medium. In laboratory, these radiative shocks are generated using high power lasers. New diagnostics have been implemented to study the geometrical shape of the shock and the front shock density. Data were obtained varying initial conditions for different laser intensities and temperature. The modeling of these phenomena is mainly performed through numerical simulations (1D and 2D) and analytical studies. We exhibit results obtained from several radiative hydrodynamics codes. As a result, it is possible to discuss about the influence of the geometry and physical parameters introduced in the 1D and 2D models.

  1. Experimental and numerical study of open-air active cooling

    NASA Astrophysics Data System (ADS)

    Al-Fifi, Salman Amsari

    The topic of my thesis is Experimental and Numerical Study of Open Air Active Cooling. The present research is intended to investigate experimentally and Numerically the effectiveness of cooling large open areas like stadiums, shopping malls, national gardens, amusement parks, zoos, transportation facilities and government facilities or even in buildings outdoor gardens and patios. Our cooling systems are simple cooling fans with different diameters and a mist system. This type of cooling systems has been chosen among the others to guarantee less energy consumption, which will make it the most favorable and applicable for cooling such places mentioned above. In the experiments, the main focus is to study the temperature domain as a function of different fan diameters aerodynamically similar in different heights till we come up with an empirical relationship that can determine the temperature domain for different fan diameters and for different heights of these fans. The experimental part has two stages. The first stage is devoted to investigate the maximum range of airspeed and profile for three different fan diameters and for different heights without mist, while the second stage is devoted to investigate the maximum range of temperature and profile for the three different diameter fans and for different heights with mist. The computational study is devoted to built an experimentally verified mathematical model to be used in the design and optimization of water mist cooling systems, and to compare the mathematical results to the experimental results and to get an insight of how to apply such evaporative mist cooling for different places for different conditions. In this study, numerical solution is presented based on experimental conditions, such dry bulb temperature, wet bulb temperature, relative humidity, operating pressure and fan airspeed. In the computational study, all experimental conditions are kept the same for the three fans except the fan airspeed

  2. Comparative study of minutiae selection algorithms for ISO fingerprint templates

    NASA Astrophysics Data System (ADS)

    Vibert, B.; Charrier, C.; Le Bars, J.-M.; Rosenberger, C.

    2015-03-01

    We address the selection of fingerprint minutiae given a fingerprint ISO template. Minutiae selection plays a very important role when a secure element (i.e. a smart-card) is used. Because of the limited capability of computation and memory, the number of minutiae of a stored reference in the secure element is limited. We propose in this paper a comparative study of 6 minutiae selection methods including 2 methods from the literature and 1 like reference (No Selection). Experimental results on 3 fingerprint databases from the Fingerprint Verification Competition show their relative efficiency in terms of performance and computation time.

  3. Theoretical and experimental studies of baroclinic processes

    NASA Technical Reports Server (NTRS)

    Miller, Tim; Leslie, Fred W.; Chou, Shih-Hung; Reynolds, Nathaniel; Lu, H.-I.; Butler, Karen

    1990-01-01

    The geophysical fluid flow simulation code, GEOSIM, is being used to study the phenomenon of vacillation in the baroclinic annulus. Having verified that the code predicts vacillation for the same points as the experiments, the work is aiming toward explaining the mechanics of vacillation and pointing out some of the sensitivities of the results to the numerical method. Researchers are finding that there is a structural change associated with amplitude vacillation, where the structural changes are in the vertical. The results disagree with the premise of Lindzen et al, that the vacillation is due to constructive and destructive interference of neutral modes with different phase speeds. The researchers are continuing to study the Spacelab 3 Geophysical Fluid Flow Cell (GFFC) results with horizontal temperature gradients and heating from below. GEOSIM has been used to compute a wide range of cases, and these are being compared with the observations. The computations and observations compare well, and the model is being used to extend the results beyond cases studied in the experiments and to study the mechanics and predictability of the flows. The study of fully nonlinear baroclinic instability using the GFFC apparatus is proceeding with the numerical code. While the first instability that occurs is of planetary scale, secondary instabilities consisting of small-scale, penetrative convection occurs where cold fluid flows over a warm surface. The simultaneous modeling of the planetary scale and the convective scale is possible because of the nonhydrostatic formulation of the model. Some of these results have been animated on the Stardent computer, which shows the explosive nature of the small-scale convection.

  4. Experimental Study of Gas Hydrate Dynamics

    NASA Astrophysics Data System (ADS)

    Fandino, O.; Ruffine, L.

    2011-12-01

    Important quantities of methane and other gases are trapped below the seafloor and in the permafrost by an ice-like solid, called gas hydrates or clathrate hydrates. The latter is formed when water is mixing with different gases at high pressures and low temperatures. Due to a their possible use as a source of energy [1] or the problematic related to flow assurance failure in pipelines [2] the understanding of their processes of formation/destabilisation of these structures becomes a goal for many laboratories research as well as industries. In this work we present an experimental study on the stochastic behaviour of hydrate formation from a bulk phase. The method used here for the experiments was to repeat several time the same hydrate formation procedure and to notice the different from one experiment to another. A variable-volume type high-pressure apparatus with two sapphire windows was used. This device, already presented by Ruffine et al.[3], allows us to perform both kinetics and phase equilibrium measurements. Three initial pressure conditions were considered here, 5.0 MPa, 7.5 MPa and 10.0 MPa. Hydrates have been formed, then allowed to dissociate by stepwise heating. The memory effect has also been investigated after complete dissociation. It turned out that, although the thermodynamics conditions of formation and/or destabilization were reproducible. An attempt to determine the influence of pressure on the nucleation induction time will be discussed. References 1. Sum, A. K.; Koh, C. A.; Sloan, E. D., Clathrate Hydrates: From Laboratory Science to Engineering Practice. Industrial & Engineering Chemistry Research 2009, 48, 7457-7465. 2. Sloan, E. D., A changing hydrate paradigm-from apprehension to avoidance to risk management. Fluid Phase Equilibria 2005, 228, 67-74. 3. Ruffine, L.; Donval, J. P.; Charlou, J. L.; Cremière, A.; Zehnder, B. H., Experimental study of gas hydrate formation and destabilisation using a novel high-pressure apparatus. Marine

  5. Theoretical and experimental studies on the foundation theoretical and experimental studies on the foundation of mesomechanics

    NASA Astrophysics Data System (ADS)

    Chudnovsky, A.; Wu, S.

    1992-06-01

    The report summarizes a closely coupled experimental and theoretical investigation of various stages of Fracture Process: (1) accumulation of 'damage' on submicroscopical and microscopical scales leading to crack initiation; (2) slow (subcritical) crack growth and an evolution of the damage zone; (3) transition to dynamic crack growth and the catastrophic failure. The experimental part of the program is focused on the observation and quantitative characterization of damage preceding and accompanying crack initiation and growth. A special experimental setup for studying the fracture process under variable stress field is reported in Chapter 2. A leading role of crack-damage interaction in fracture process is well documented. A new formalism for solution of crack-microcrack array interaction problem and its successful implementation in the evaluation of crack layer driving forces is presented in Chapter 3. A new model of the process zone, which generalizes the well-known Dagdale-Barenblatt model is presented in Chapter 4. A new measure for material toughness and the prediction of R-curve behavior illustrate the practical application of our model. Experimental examinations of our model under various test conditions are reported in Chapters 4, 5 and 6. The development of the constitutive equations for Crack Layer evolution and their experimental examinations under stress relaxation, fatigue and creep conditions are reported in Chapters 5 and 6. An accelerated test procedure and the formulation of crack layer instability criteria as a substitution for the conventional fracture toughness parameters are also discussed in Chapter 6.

  6. Comparative Study of Two Automatic Registration Algorithms

    NASA Astrophysics Data System (ADS)

    Grant, D.; Bethel, J.; Crawford, M.

    2013-10-01

    The Iterative Closest Point (ICP) algorithm is prevalent for the automatic fine registration of overlapping pairs of terrestrial laser scanning (TLS) data. This method along with its vast number of variants, obtains the least squares parameters that are necessary to align the TLS data by minimizing some distance metric between the scans. The ICP algorithm uses a "model-data" concept in which the scans obtain differential treatment in the registration process depending on whether they were assigned to be the "model" or "data". For each of the "data" points, corresponding points from the "model" are sought. Another concept of "symmetric correspondence" was proposed in the Point-to-Plane (P2P) algorithm, where both scans are treated equally in the registration process. The P2P method establishes correspondences on both scans and minimizes the point-to-plane distances between the scans by simultaneously considering the stochastic properties of both scans. This paper studies both the ICP and P2P algorithms in terms of their consistency in registration parameters for pairs of TLS data. The question being investigated in this paper is, should scan A be registered to scan B, will the parameters be the same if scan B were registered to scan A? Experiments were conducted with eight pairs of real TLS data which were registered by the two algorithms in the forward (scan A to scan B) and backward (scan B to scan A) modes and the results were compared. The P2P algorithm was found to be more consistent than the ICP algorithm. The differences in registration accuracy between the forward and backward modes were negligible when using the P2P algorithm (mean difference of 0.03 mm). However, the ICP had a mean difference of 4.26 mm. Each scan was also transformed by the forward and backward parameters of the two algorithms and the misclosure computed. The mean misclosure for the P2P algorithm was 0.80 mm while that for the ICP algorithm was 5.39 mm. The conclusion from this study is

  7. Experimental Study of Olivine-rich Troctolites

    NASA Astrophysics Data System (ADS)

    Mu, S.; Faul, U.

    2014-12-01

    This experimental study is designed to complement field observations of olivine-rich troctolites in ophiolites and from mid-ocean ridges. The olivine-rich troctolites are characterized by high volume proportion of olivine with interstitial plagioclase and clinopyroxene. Typically the clinopyroxene occurs in the form of few large, poikilitic grains. The primary purpose of this study is to investigate the effects of cooling process on the geometry of the interstitial phases (clinopyroxene and plagioclase). Experiments are conducted in a piston cylinder apparatus by first annealing olivine plus a basaltic melt with a composition designed to be in equilibrium with four phases at ~ 1 GPa and 1250ºC. Initially, we anneal the olivine-basalt aggregates at 1350 °C and 0.7 GPa for one week to produce a steady state microstructure. At this temperature only olivine and minor opx are present as crystalline phases. We then cool the samples over two weeks below their solidus temperature, following different protocols. The post-run samples are sectioned, polished, and imaged at high resolution and analyzed by using a field emission SEM. Initial observations show that under certain conditions clinopyroxene nucleates distributed throughout the aggregate at many sites, forming relatively small, rounded to near euhedral grains. Under certain conditions few cpx grains nucleate and grow with a poikilitic shape, partially or fully enclosing olivine grains, as is observed in natural samples. As for partially molten aggregates quenched form the annealing temperature, the microstructure will be characterized by tracing phase boundaries on screen by using ImageJ software. The geometry of the interstitial phases will be quantified by determining the grain boundary wetness, in this case the ratio of the length of polyphase to single phase (olivine-olivine) boundaries. Compositional data will also be used to study the change in major element compositions before and after the cooling process.

  8. Pore water pressure variations in Subpermafrost groundwater : Numerical modeling compared with experimental modeling

    NASA Astrophysics Data System (ADS)

    Rivière, Agnès.; Goncalves, Julio; Jost, Anne; Font, Marianne

    2010-05-01

    Development and degradation of permafrost directly affect numerous hydrogeological processes such as thermal regime, exchange between river and groundwater, groundwater flows patterns and groundwater recharge (Michel, 1994). Groundwater in permafrost area is subdivided into two zones: suprapermafrost and subpermafrost which are separated by permafrost. As a result of the volumetric expansion of water upon freezing and assuming ice lenses and frost heave do not form freezing in a saturated aquifer, the progressive formation of permafrost leads to the pressurization of the subpermafrost groundwater (Wang, 2006). Therefore disappearance or aggradation of permafrost modifies the confined or unconfined state of subpermafrost groundwater. Our study focuses on modifications of pore water pressure of subpermafrost groundwater which could appear during thawing and freezing of soil. Numerical simulation allows elucidation of some of these processes. Our numerical model accounts for phase changes for coupled heat transport and variably saturated flow involving cycles of freezing and thawing. The flow model is a combination of a one-dimensional channel flow model which uses Manning-Strickler equation and a two-dimensional vertically groundwater flow model using Richards equation. Numerical simulation of heat transport consisted in a two dimensional model accounting for the effects of latent heat of phase change of water associated with melting/freezing cycles which incorporated the advection-diffusion equation describing heat-transfer in porous media. The change of hydraulic conductivity and thermal conductivity are considered by our numerical model. The model was evaluated by comparing predictions with data from laboratory freezing experiments. Experimental design was undertaken at the Laboratory M2C (Univesité de Caen-Basse Normandie, CNRS, France). The device consisted of a Plexiglas box insulated on all sides except on the top. Precipitation and ambient temperature are

  9. Experimental studies of gravity with slow neutrons

    NASA Astrophysics Data System (ADS)

    Kitaguchi, Masaaki; Ichikawa, Go; Hirota, Katsuya; Shimizu, Hirohiko; Sumi, Naoyuki; Matsumoto, Satoru; Yoshioka, Tamaki; Shima, Tatsushi; Mishima, Kenji; Ino, Takashi; Seki, Yoshichika

    2014-09-01

    Neutron is a chargeless massive particle with the lifetime in the macroscopic range, which is suitable for precision measurement of the small influence of new physics including gravity. We have started the experimental studies of the gravity with slow neutrons in order to search non-Newtonian effect at the short range which is lead by the existence of extra-dimension of the space. Combination of the pulsed neutrons provided by J-PARC and the advanced optical devices enables us to perform new types of high precision measurements. Neutron scattering with noble gas target enables us to measure the interaction at the range of the order of 1 nm. The apparatus was installed into beamline NOP and commissioning has been started. Neutron interferometer has the advantage to measure the gravitational potential precisely. We are developing the large-scale interferometer using long-wavelength neutrons, which is realized by using multilayer mirrors. Ultra-cold neutrons in a small cavity can be bound to the discrete energy eigenstates by Earth's gravitational field. We are discussing the direct measurement of the spatial localization of the neutrons with high resolution detectors, for example, CCD and nuclear emulation.

  10. The experimental studies of thermoacoustic cooler.

    PubMed

    Sakamoto, Shin-ichi; Watanabe, Yoshiaki

    2004-04-01

    The experimental studies of thermoacoustic cooler consisting of acoustic loop-tube were carried out. The loop-tube was filled with the mixture of air and helium gas or air at atmospheric pressure. The dimensions of the loop-tube were 3.3 m of length, 44 mm of inner diameter and 4 mm of thickness. A pair of stacks (stack 1 and stack 2) which were sandwiched between two heat exchangers was placed symmetrically in the loop-tube. Stack 1 was employed as a prime mover and stack 2 as a heat pump. The self-sustained sound generated by the thermoacoustic effect and the cooling phenomena at the stack 2 were observed. The distribution of the sound pressures and the waveforms in the loop-tube were measured, and the frequency component of the self-sustained sound was investigated at the starting phase. The fundamental frequency component was confirmed and it was developing as the sound pressure increasing. The higher harmonics frequency components were generated and they were also developing. PMID:15047261

  11. Phosphatic fertiliser poisoning of sheep: experimental studies.

    PubMed

    O'Hara, P J; McCausland, I P; Coup, M R

    1982-11-01

    The toxicity of serpentine phosphate and superphosphate for non-pregnant dry ewes, pregnant ewes and lactating ewes was investigated by oral dosing. An attempt was made to reproduce a natural episode of poisoning by exposing pregnant and lactating ewes to topdressed pasture. A total dose in the range of 1200 to 1800 g of serpentine phosphate was required to kill two ewes and it was concluded that natural episodes of poisoning with this material are unlikely. The toxic process was similar to that caused by superphosphate. The LD50 of superphosphate was estimated to be in the range of 5 to 6 g/kg and a dose in the range of 200 to 300 g was sufficient to kill most sheep. The apparently greater susceptibility of pregnant and lactating sheep to poisoning suggested by the study of natural outbreaks was not demonstrated in these experiments, but the numbers of experimental animals may have been too small to detect differing susceptibility. The clinical disease resembled that seen in natural episodes; anorexia, diarrhoea, progressive depression and death in a period of 5 to 8 days after the start of dosing. Sublethal doses produced a transient diarrhoea and, in two sheep, a severe wool-break. The principal biochemical changes were hyperphosphataemia and evidence of renal failure (oliguria, uraemia, azotaemia). Gross lesions were not consistently present but included abomasal ulceration and renal cortical swelling and pallor. The histopathological evidence of renal tubular obstruction by flocculant eosinophilic casts was characteristic. PMID:16030836

  12. Experimental study of finite Larmor radius effects

    SciTech Connect

    Struve, K.W.

    1980-08-01

    Linear Z-pinches in Ar, Kr, Xe, N/sub 2/, and He are experimentally studied in regimes where strong finite Larmor radius effects could provide a significant stabilizing effect. Scaling arguments show that for deuterium such a pinch has an electron line density of order 2 x 10/sup 15//cm. For higher Z plasmas a higher line density is allowed, the exact value of which depends on the average ion charge. The pinch is formed by puffing gas axially through the cathode towards the anode of an evacuated pinch chamber. When the gas reaches the anode, the pinch bank is fired. The pinch current rises in 2 to 3 ..mu..sec to a maximum of 100 to 200 kA. The pinch bank capacitance is 900 ..mu..F, and the external inductance is 100 nH. Additionally, the bank is fused to increase dI/dt. The primary diagnostics are a framing camera, a spatially resolved Mach-Zehnder interferometer, and X-ray absorption.

  13. Experimental studies of gas-aerosol reactions

    NASA Astrophysics Data System (ADS)

    Gupta, Anand

    1991-05-01

    The aqueous phase oxidation of SO2 by H2O2 is believed to the principle mechanism for atmospheric sulfate formation in cloud droplets. However, no studies in noncloud aerosol systems have been reported. The objective is to quantify the importance of the noncloud liquid phase reactions of SO2 by H2O2 in the atmosphere. Growth rates of submicron droplets exposed to SO2 and H2O2 were measured using the tandem differential mobility analyzer (TDMA) technique (Rader and McMurry, 1986). The technique uses differential mobility analyzers (DMA's) to generate monodisperse particles and to measure particle size after the reaction. To facilitate submicron monodisperse droplet production with the DMA, a low-ion-concentration charter capable of generating singly charged particles up to 1.0 microns was developed and experimentally evaluated. The experiments were performed using dry and deliquesced (NH4)2SO4 particles with SO2 and H2O2 concentrations from 0-860 ppb and 0-150 ppb, respectively. No growth was observed for dry particles. For droplets greater than or equal to 0.3 microns, the fractional diameter growth was independent of particle size and for droplets less than or equal to 0.2 microns, it decreased as particle size decreased. The observed decrease is due to NH3 evaporation. As ammonia evaporates, droplet pH decreases causing the oxidation rate to decrease, leading to a lower growth rate. To predict the size-dependent growth rates, a theoretical model was developed using solution thermodynamics, gas/particle equilibrium, and chemical kinetics. The experimental and theoretical results are in reasonable agreement. For dry (NH4)2SO4 particles exposed to SO2, H2O2, NH3, and H2O vapor, surface reaction-controlled growth was observed. Particle growth was very sensitive to particle composition. No growth was observed for Polystyrene latex particles, whereas (NH4)2SO4 particles doped with catalysts (Fe(2+), Fe(3+), Mn(2+) and Cu(2+)) in a molar ratio of 1:500 grew slower than

  14. Analytical Bistatic k Space Images Compared to Experimental Swept Frequency EAR Images

    NASA Technical Reports Server (NTRS)

    Shaeffer, John; Cooper, Brett; Hom, Kam

    2004-01-01

    A case study of flat plate scattering images obtained by the analytical bistatic k space and experimental swept frequency ISAR methods is presented. The key advantage of the bistatic k space image is that a single excitation is required, i.e., one frequency I one angle. This means that prediction approaches such as MOM only need to compute one solution at a single frequency. Bistatic image Fourier transform data are obtained by computing the scattered field at various bistatic positions about the body in k space. Experimental image Fourier transform data are obtained from the measured response to a bandwidth of frequencies over a target rotation range.

  15. Experimental Study of Lunar and SNC Magmas

    NASA Technical Reports Server (NTRS)

    Rutherford, Malcolm J.

    1998-01-01

    The research described in this progress report involved the study of petrological, geochemical and volcanic processes that occur on the Moon and the SNC parent body, generally accepted to be Mars. The link between these studies is that they focus on two terrestrial-type parent bodies somewhat smaller than earth, and the fact that they focus on the role of volatiles in magmatic processes and on processes of magma evolution on these planets. The work on the lunar volcanic glasses has resulted in some exciting new discoveries over the years of this grant. We discovered small metal blebs initially in the Al5 green glass, and determined the significant importance of this metal in fixing the oxidation state of the parent magma (Fogel and Rutherford, 1995). More recently, we discovered a variety of metal blebs in the Al7 orange glass. Some of these Fe-Ni metal blebs were in the glass; others were in olivine phenocrysts. The importance of these metal spheres is that they fix the oxidation state of the parent magma during the eruption, and also indicate changes during the eruption (Weitz et al., 1997) They also yield important information about the composition of the gas phase present, the gas which drove the lunar fire-fountaining. One of the more exciting and controversial findings in our research over the past year has been the possible fractionation of H from D during shock (experimental) of hornblende bearing samples (Minitti et al., 1997). This research is directed at explaining some of the low H2O and high D/H observed in hydrous phases in the SNC meteorites.

  16. Experimental Vibration Study on the Healthy and Delaminated Composite Plates

    NASA Astrophysics Data System (ADS)

    Ullah, Israr; Sinha, Jyoti K.

    2011-07-01

    Vibration based damage, in particular delamination detection, in the composite structures is an active research area. The present study is also on the dynamics of the composite plates with and without delamination based on the experimental study. The test plate made of E-glass fibre and epoxy resins has been used here. A piezo-electric shaker has been used to excite the composite plate and the acceleration responses were measured using the number of accelerometers. The dynamics of the delaminated composite plates were then compared with a healthy composite plate when the vibration experiments have been conducted at the lower modes. The paper will discuss the observations made on the measured vibration responses from both the healthy and the delaminated plates and the possibility of the delamination detection from the experimental vibration data.

  17. Experimental and computational studies of nanofluids

    NASA Astrophysics Data System (ADS)

    Vajjha, Ravikanth S.

    The goals of this dissertation were (i) to experimentally investigate the fluid dynamic and heat transfer performance of nanofluids in a circular tube, (ii) to study the influence of temperature and particle volumetric concentration of nanofluids on thermophysical properties, heat transfer and pumping power, (iii) to measure the rheological properties of various nanofluids and (iv) to investigate using a computational fluid dynamic (CFD) technique the performance of nanofluids in the flat tube of a radiator. Nanofluids are a new class of fluids prepared by dispersing nanoparticles with average sizes of less than 100 nm in traditional heat transfer fluids such as water, oil, ethylene glycol and propylene glycol. In cold regions of the world, the choice of base fluid for heat transfer applications is an ethylene glycol or propylene glycol mixed with water in different proportions. In the present research, a 60% ethylene glycol (EG) or propylene glycol (PG) and 40% water (W) by mass fluid mixture (60:40 EG/W or 60:40 PG/W) was used as a base fluid, which provides freeze protection to a very low level of temperature. Experiments were conducted to measure the convective heat transfer coefficient and pressure loss of nanofluids flowing in a circular tube in the fully developed turbulent regime. The experimental measurements were carried out for aluminum oxide (Al2O3), copper oxide (CuO) and silicon dioxide (SiO2) nanoparticles dispersed in 60:40 EG/W base fluid. Experiments revealed that the heat transfer coefficient of nanofluids showed an increase with the particle volumetric concentration. Pressure loss was also observed to increase with the nanoparticle volumetric concentration. New correlations for the Nusselt number and the friction factor were developed. The effects of temperature and particle volumetric concentration on different thermophysical properties (e.g. viscosity, thermal conductivity, specific heat and density) and subsequently on the Prandtl number

  18. Evapotranspiration studies for protective barriers: Experimental plans

    SciTech Connect

    Link, S.O.; Waugh, W.J.

    1989-11-01

    This document describes a general theory and experimental plans for predicting evapotranspiration in support of the Protective Barrier Program. Evapotranspiration is the combined loss of water from plants and soil surfaces to the atmosphere. 45 refs., 1 fig., 4 tabs.

  19. A COMPARATIVE STUDY OF VIDEO TAPE RECORDINGS.

    ERIC Educational Resources Information Center

    WIENS, JACOB H.

    THE COMPARATIVE EFFECTIVENESS OF PRESENTLY AVAILABLE VIDEO TAPE MACHINES IS REPORTED, FOR THE CONVENIENCE OF SCHOOL ADMINISTRATORS PLANNING TO USE SUCH EQUIPMENT IN EDUCATIONAL PROGRAMS. TESTS WERE CONDUCTED AT THE WIENS ELECTRONIC LABORATORIES. MACHINE BRANDS TESTED WERE AMPEX, CONCORD, MACHTRONICS, PRECISION, RCA, SONY, AND WOLLENSAK. A DETAILED…

  20. Flip This Classroom: A Comparative Study

    ERIC Educational Resources Information Center

    Unruh, Tiffany; Peters, Michelle L.; Willis, Jana

    2016-01-01

    The purpose of this research was to compare the beliefs and attitudes of teachers using the flipped versus the traditional class model. Survey and interview data were collected from a matched sample of in-service teachers representing both models from a large suburban southeastern Texas school district. The Attitude Towards Technology Scale, the…

  1. Counseling in Costa Rica: A Comparative Study

    ERIC Educational Resources Information Center

    Collier, Crystal

    2013-01-01

    With one of the world's most comprehensive universal healthcare systems, medical tourism in Costa Rica has increased significantly over the past few decades. American tourists save up to 80% of comparative costs for procedures, from heart surgery to root canal treatment. Although many Costa Rican healthcare professionals receive training in North…

  2. Experimental and computational studies of nanofluids

    NASA Astrophysics Data System (ADS)

    Vajjha, Ravikanth S.

    The goals of this dissertation were (i) to experimentally investigate the fluid dynamic and heat transfer performance of nanofluids in a circular tube, (ii) to study the influence of temperature and particle volumetric concentration of nanofluids on thermophysical properties, heat transfer and pumping power, (iii) to measure the rheological properties of various nanofluids and (iv) to investigate using a computational fluid dynamic (CFD) technique the performance of nanofluids in the flat tube of a radiator. Nanofluids are a new class of fluids prepared by dispersing nanoparticles with average sizes of less than 100 nm in traditional heat transfer fluids such as water, oil, ethylene glycol and propylene glycol. In cold regions of the world, the choice of base fluid for heat transfer applications is an ethylene glycol or propylene glycol mixed with water in different proportions. In the present research, a 60% ethylene glycol (EG) or propylene glycol (PG) and 40% water (W) by mass fluid mixture (60:40 EG/W or 60:40 PG/W) was used as a base fluid, which provides freeze protection to a very low level of temperature. Experiments were conducted to measure the convective heat transfer coefficient and pressure loss of nanofluids flowing in a circular tube in the fully developed turbulent regime. The experimental measurements were carried out for aluminum oxide (Al2O3), copper oxide (CuO) and silicon dioxide (SiO2) nanoparticles dispersed in 60:40 EG/W base fluid. Experiments revealed that the heat transfer coefficient of nanofluids showed an increase with the particle volumetric concentration. Pressure loss was also observed to increase with the nanoparticle volumetric concentration. New correlations for the Nusselt number and the friction factor were developed. The effects of temperature and particle volumetric concentration on different thermophysical properties (e.g. viscosity, thermal conductivity, specific heat and density) and subsequently on the Prandtl number

  3. Industrial Noise and Tooth Wear - Experimental Study

    PubMed Central

    Cavacas, Maria Alzira; Tavares, Vitor; Borrecho, Gonçalo; Oliveira, Maria João; Oliveira, Pedro; Brito, José; Águas, Artur; dos Santos, José Martins

    2015-01-01

    Tooth wear is a complex multifactorial process that involves the loss of hard dental tissue. Parafunctional habits have been mentioned as a self-destructive process caused by stress, which results in hyperactivity of masticatory muscles. Stress manifests itself through teeth grinding, leading to progressive teeth wear. The effects of continuous exposure to industrial noise, a “stressor” agent, cannot be ignored and its effects on the teeth must be evaluated. Aims: The aim of this study was to ascertain the effects of industrial noise on dental wear over time, by identifying and quantifying crown area loss. Material and Methods: 39 Wistar rats were used. Thirty rats were divided in 3 experimental groups of 10 animals each. Animals were exposed to industrial noise, rich in LFN components, for 1, 4 and 7 months, with an average weekly exposure of 40 hours (8h/day, 5 days/week with the weekends in silence). The remaining 9 animals were kept in silence. The areas of the three main cusps of the molars were measured under light microscopy. Statistical analysis used: A two-way ANOVA model was applied at significance level of 5%. Results: The average area of the molar cusps was significantly different between exposed and non-exposed animals. The most remarkable differences occurred between month 1 and 4. The total crown loss from month 1 to month 7 was 17.3% in the control group, and 46.5% in the exposed group, and the differences between these variations were significant (p<0.001). Conclusions: Our data suggest that industrial noise is an important factor in the pathogenesis of tooth wear. PMID:25798052

  4. Bacterial contamination control mats: a comparative study.

    PubMed Central

    Meddick, H. M.

    1977-01-01

    The ability of six different types of contamination control mats currently in use at the entrances to theatre suites and other clean areas to remove bacteria-carrying particles from theatre trolley wheeels was compared. Marked differences in the effectiveness of this property were obtained; and all mats showed some disadvantages. Modification of one of the mats has resulted in improved efficiency under working conditions. Images Plate 1 PMID:267665

  5. Biomass thermochemical gasification: Experimental studies and modeling

    NASA Astrophysics Data System (ADS)

    Kumar, Ajay

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

  6. Computatonal and experimental study of laminar flames

    SciTech Connect

    Smooke, M.D.; Long, M.B.

    1993-12-01

    This research has centered on an investigation of the effects of complex chemistry and detailed transport on the structure and extinction of hydrocarbon flames in counterflow, cylindrical and coflowing axisymmetric configurations. The authors have pursued both computational and experimental aspects of the research in parallel. The computational work has focused on the application of accurate and efficient numerical methods for the solution of the one and two-dimensional nonlinear boundary value problems describing the various reacting systems. Detailed experimental measurements were performed on axisymmetric coflow flames using two-dimensional imaging techniques. In particular, spontaneous Raman scattering and laser induced fluorescence were used to measure the temperature, major and minor species profiles.

  7. Experimental study of uncentralized squeeze film dampers

    NASA Technical Reports Server (NTRS)

    Quinn, R. D.

    1983-01-01

    The vibration response of a rotor system supported by a squeeze film damper (SFD) was experimentally investigated in order to provide experimental data in support of the Rotor/Stator Interactive Finite Element theoretical development. Part of the investigation required the designing and building of a rotor/SFD system that could operate with or without end seals in order to accommodate different SFD lengths. SFD variables investigated included clearance, eccentricity mass, fluid pressure, and viscosity and temperature. The results show inlet pressure, viscosity and clearance have significant influence on the damper performance and accompanying rotor response.

  8. Comparative transport studies of ``1212'' superconductors

    SciTech Connect

    GAPUD,ALBERT; WU,JUDY; YAN,SHAOLIN; XIE,YI-YUAN; KANG,BYEONGWON; SIEGAL,MICHAEL P.; OVERMYER,DONALD L.

    2000-05-17

    HgBa{sub 2}CaCu{sub 2}O{sub 6+{delta}} (Hg-1212) thin films were fabricated by exchanging the TI cations in TlBa{sub 2}CaCu{sub 2}O{sub 7-{delta}} (Tl-1212) thin films with Hg cations, causing a 30-K increase in Tc. To determine how this exchange effects such a Tc increase, the irreversibility lines, temperature dependence of critical current density, and temperature dependence of Hall angle of Hg-1212 and T1-1212 thin films were measured and then compared. The results strongly suggest that the Tc shift is caused by a doubling of charge carrier density.

  9. Comparative study of some new EPR dosimeters

    NASA Astrophysics Data System (ADS)

    Alzimami, K. S.; Maghraby, Ahmed M.; Bradley, D. A.

    2014-02-01

    Investigations have been made of four new radiation dosimetry EPR candidates from the same family of materials: sulfamic acid, sulfanillic acid, homotaurine, and taurine. Mass energy attenuation coefficients, mass stopping power values and the time dependence of the radiation induced radicals are compared. Also investigated are the microwave saturation behavior and the effect of applied modulation amplitude on both peak-to-peak line width (WPP) and peak-to-peak signal height (HPP). The dosimeters are characterized by simple spectra and stable radiation-induced radicals over reasonable durations, especially in taurine dosimeters. Sulfamic acid dosimeters possessed the highest sensitivity followed by taurine and homotaurine and sulfanillic.

  10. COMPARATIVE STUDIES OF HERPETOMONADS AND LEISHMANIAS

    PubMed Central

    Noguchi, Hideyo; Tilden, Evelyn B.

    1926-01-01

    obtained in culture, all the strains grow well on leptospira medium, as well as on blood slants. Growth takes place both at 26°C. and at 37°. The morphology of the organisms is considerably modified by cultivation. This is especially true of the plant flagellates. In the latex they have ribbon-like bodies, often twisted, and comparatively short flagella; the protoplasm is clear, almost hyaline. The flagellates seen in the gut and feces of insects are usually large, slender organisms, with flagella as long as or even longer than the body, which contains numerous volutin granules in the cytoplasm. In cultures under parallel conditions the flagellates from both these sources become shorter and thicker, the plant forms no longer appear flat and ribbon-like, and in general the organisms approach one another in morphological features. Even in the case of the least modified insect flagellates, i.e. those from flies, there is never exact correspondence between the natural and the cultivated forms. The morphological features of the cultivated flagellates vary according to the medium on which the organisms are grown and the age of the culture. The flagellates grown on the surface of blood slants are pyriform, with truncated anterior portion, and short flagellum; in the condensation water, however, the individuals are elongated and have long active flagella. On the leptospira medium the slender active forms with long flagella predominate. In the presence of fermentable carbohydrate, or in medium containing considerable acid, peculiar bifurcated or multifurcated individuals are seen. Similar forms have been seen under natural conditions. Cultures of Leishmania behave in the same way under the conditions described. There is a striking difference in rapidity of growth between the organisms isolated by us and the leishmanias, H. ctenocephali, and T. rotatorium. While the stock cultures of the group first mentioned multiply rapidly at 37°C., growth becoming visible within 24 hours, the