2,085 research outputs found

    Effect of industrial wastewater ontotal protein and the peroxidase activity in plants

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    The aim of this study is to investigate the effects of industrial wastewaters on protein and the peroxidase activity in Lycopersicon esculentum Mill., Capsicum annuum L., Phaseolus vulgaris L. and Vicia faba L. Industrial wastewaters were taken from Dardanel Fisheries Company, Tekel alcoholicdrinks companies’ wastewater treatment plants and from one station which is located in the middle of the Sarýçay River. Wastewaters were applied to 6 weeks old plants with directly irrigation water. Physiological changes in the plants were observed by the means of measuring the protein and enzyme activity. The largest increase in protein was observed as 190.9 and 136.3% in V. faba treated with Sarýçay River water and Tekel wastewater, respectively. In P. vulgaris which was treated with Dardanelwastewater, the total protein amount increased by 84% compared to control plants. After the wastewater treatment, the peroxidase activity decreased in all plants. The largest peroxidase decrease was 80% in L. esculentum treated with Tekel wastewater. In P. vulgaris, peroxidase decreased by 59 and 51% when treated with Dardanel wastewater and Sarýçay River water, respectively. It was concluded that the increase in total protein amount and the decrease in peroxidase activity demonstrated theindustrial wastewater’s blocking effects on plants defense systems

    Ola Bratteli and his diagrams

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    This article discusses the life and work of Professor Ola Bratteli (1946--2015). Family, fellow students, his advisor, colleagues and coworkers review aspects of his life and his outstanding mathematical accomplishments.Comment: 18 pages, 15 figure

    Quasinormal ringing of acoustic black holes in Laval nozzles: Numerical simulations

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    Quasinormal ringing of acoustic black holes in Laval nozzles is discussed. The equation for sounds in a transonic flow is written into a Schr\"{o}dinger-type equation with a potential barrier, and the quasinormal frequencies are calculated semianalytically. From the results of numerical simulations, it is shown that the quasinormal modes are actually excited when the transonic flow is formed or slightly perturbed, as well as in the real black hole case. In an actual experiment, however, the purely-outgoing boundary condition will not be satisfied at late times due to the wave reflection at the end of the apparatus, and a late-time ringing will be expressed as a superposition of "boxed" quasinormal modes. It is shown that the late-time ringing damps more slowly than the ordinary quasinormal ringing, while its central frequency is not greatly different from that of the ordinary one. Using this fact, an efficient way for experimentally detecting the quasinormal ringing of an acoustic black hole is discussed.Comment: 9 pages, 8 figures, accepted for publication in Physical Review

    Electronic Structures of N-doped Graphene with Native Point Defects

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    Nitrogen doping in graphene has important implications in graphene-based devices and catalysts. We have performed the density functional theory calculations to study the electronic structures of N-doped graphene with vacancies and Stone-Wales defect. Our results show that monovacancies in graphene act as hole dopants and that two substitutional N dopants are needed to compensate for the hole introduced by a monovacancy. On the other hand, divacancy does not produce any free carriers. Interestingly, a single N dopant at divacancy acts as an acceptor rather than a donor. The interference between native point defect and N dopant strongly modifies the role of N doping regarding the free carrier production in the bulk pi bands. For some of the defects and N dopant-defect complexes, localized defect pi states are partially occupied. Discussion on the possibility of spin polarization in such cases is given. We also present qualitative arguments on the electronic structures based on the local bond picture. We have analyzed the 1s-related x-ray photoemission and adsorption spectroscopy spectra of N dopants at vacancies and Stone-Wales defect in connection with the experimental ones. We also discuss characteristic scanning tunneling microscope (STM) images originating from the electronic and structural modifications by the N dopant-defect complexes. STM imaging for small negative bias voltage will provide important information about possible active sites for oxygen reduction reaction.Comment: 40 pages, 2 tables, 16 figures. The analysis of Clar sextets is added. This version is published on PHYSICAL REVIEW B 87, 165401(2013

    Study of Scattered Light from Known Debris Disks

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    Using the Spitzer Space Telescope, a group of edge on debris disks, surrounding main-sequence shell stars have been discovered in the infrared. These disks are of high interest because they not only have dust, but an observed amount of circumstellar gas. HD158352 was an ideal target to try and image the disk because it was one of the closest stars in this group. Using the Hubble Space Telescope's Space Telescope Imaging Spectrograph (STIS), we attempted to take a direct image of the light scattered from the known disk in a broad optical bandpass. Studying these particular type of disks in high detail will allow us to learn more about gas-dust interactions. In particular, this will allow us to learn how the circumstellar gas evolves during the planet-forming phase. Even though it was predicted that the disk should have a magnitude of 20.5 at 3", no disk was seen in any of the optical images. This suggests that the parameters used to predict the brightness of the disk are not what we first anticipated and adjustments to the model must be performed. We also present the blue visible light spectrum of the scattered light from the debris disk surrounding Beta Pictoris. We are analyzing archival observations taken by Heap, using Hubble Space Telescope's STIS instrument. A long slit with a bar was used to occult Beta Pictoris as well as the PSF star. This was done because it is necessary to subtract a PSF observed the same way at the target to detect the disk. It appears that we have detected light from the disk but the work was in progress at the time of the abstract deadline

    UNDERSTANDING ELITE SPRINT START PERFORMANCE THROUGH AN ANALYSIS OF JOINT KINEMATICS

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    This study aimed to investigate how leg kinematics contribute to the performance, in terms of external horizontal power production, of three elite sprinters during the block and first step phases of a sprint. The highest block phase power was produced by sprinter B, who exhibited the greatest hip extension, particularly at the rear leg. Sprinter A achieved a higher horizontal block exit velocity, however, this appeared to be due to a longer push duration rather than greater average force production. The highest horizontal power during the first stance was again produced by sprinter B, who exhibited the greatest total stance leg joint extension. The other two sprinters exhibited similar leg extension to each other. However, sprinter A was able to generate greater horizontal power, which may have been due to his centre of mass being further in front of his foot at touchdown

    High Ratio of 44Ti/56Ni in Cas A and Axisymmetric Collapse-Driven Supernova Explosion

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    The large abundance ratio of 44Ti/56Ni^{44}Ti/^{56}Ni in Cas A is puzzling. In fact, the ratio seems to be larger than the theoretical constraint derived by Woosley & Hoffman (1991). However, this constraint is obtained on the assumption that the explosion is spherically symmetric, whereas Cas A is famous for the asymmetric form of the remnant. Recently, Nagataki et al. (1997) calculated the explosive nucleosynthesis of axisymmetrically deformed collapse-driven supernova. They reported that the ratio of 44Ti/56Ni^{44}Ti/^{56}Ni was enhanced by the stronger alpha-rich freezeout in the polar region. In this paper, we apply these results to Cas A and examine whether this effect can explain the large amount of 44Ti^{44}Ti and the large ratio of 44Ti/56Ni^{44}Ti/^{56}Ni. We demonstrate that the conventional spherically symmetric explosion model can not explain the 44^{44}Ti mass produced in Cas A if its lifetime is shorter than ∼\sim 80 years and the intervening space is transparent to the gamma-ray line from the decay of 44^{44}Ti. On the other hand, we show the axisymmetric explosion models can solve the problem. We expect the same effect from a three dimensionally asymmetric explosion, since the stronger alpha-rich freezeout will also occur in that case in the region where the larger energy is deposited.Comment: 10 pages, LaTeX text and 3 postscript figure

    Measurement Error in Estimates of Sprint Velocity from a Laser Displacement Measurement Device

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    This study aimed to determine the measurement error associated with estimates of velocity from a laser-based device during different phases of a maximal athletic sprint. Laser-based displacement data were obtained from 10 sprinters completing a total of 89 sprints and were fitted with a fifth-order polynomial function which was differentiated to obtain instantaneous velocity data. These velocity estimates were compared against criterion high-speed video velocities at either 1, 5, 10, 30 or 50 m using a Bland-Altman analysis to assess bias and random error. Bias was highest at 1 m (+ 0.41 m/s) and tended to decrease as the measurement distance increased, with values less than + 0.10 m/s at 30 and 50 m. Random error was more consistent between distances, and reached a minimum value (±0.11 m/s) at 10 m. Laser devices offer a potentially useful time-efficient tool for assessing between-subject or between-session performance from the mid-acceleration and maximum velocity phases (i. e., at 10 m and beyond), although only differences exceeding 0.22-0.30 m/s should be considered genuine. However, laser data should not be used during the first 5 m of a sprint, and are likely of limited use for assessing within-subject variation in performance during a single session

    Modeling the stance leg in two-dimensional analyses of sprinting:Inclusion of the MTP joint affects joint kinetics

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    Two-dimensional analyses of sprint kinetics are commonly undertaken but often ignore the metatarsalphalangeal (MTP) joint and model the foot as a single segment. Due to the linked-segment nature of inverse dynamics analyses, the aim of this study was to investigate the effect of ignoring the MTP joint on the calculated joint kinetics at the other stance leg joints during sprinting. High-speed video and force platform data were collected from four to five trials for each of three international athletes. Resultant joint moments, powers, and net work at the stance leg joints during the first stance phase after block clearance were calculated using three different foot models. By ignoring the MTP joint, peak extensor moments at the ankle, knee, and hip were on average 35% higher (p .05), respectively, than those calculated with the MTP joint included. Peak ankle and knee joint powers and net work at all joints were also significantly (p < .05) different. By ignoring a genuine MTP joint plantar flexor moment, artificially high peak ankle joint moments are calculated, and these also affect the calculated joint kinetics at the knee
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