Development of the moss Pogonatum urnigerum (Hedw.) P. Beauv. under in vitro culture conditions

Pogonatum urnigerum (Polytrichaceae) in vitro culture was established from spores collected in nature. Both protonema and gametophore stages of gametophyte development were obtained. Also, a stable callus culture was established using hormone-free nutrient medium. The best nutrient medium for development was half-strength Murashige-Skoog medium supplemented with 1.5% sucrose. Auxin treatment enabled some gametophores to develop, but prolonged treatment induced early senescence. Tissues grown on cytokinin did not produce any gametophytes and did not survive prolonged treatment.Sterilna kultura mahovine Pogonatum urnigerum (Polytrichaceae) uspostavljena je iz spora sakupljenih u prirodi. Gajenjem na hranljivoj podlozi bez biljnih hormona iz spora su se razvile protoneme i gametofiti. Uspostavljena je i stabilna kultura kalusa. Ustanovljeno je da je za gajenje ove vrste najbolja hranljiva podloga koja sadrži smanjenu koncentraciju soli i vitamina po Murashige-Skoog-u i 1.5% saharozu. Tretman auksinom nije pospešio razviće gametofita, dok je produženi tretman doveo do postepenog odumiranja protoneme. Tkiva gajena na podlozi koja je sadržala citokinine uopšte nisu produkovala gametofite i nisu preživela produženi tretman ovim hormonom. Ovaj rad predstavlja prvu studiju razvića vrste Pogonatum urnigerum u in vitro kulturi.nul

Isokinetic Testing: Sensitivity of the Force-Velocity Relationship Assessed through the Two-Point Method to Discriminate between Muscle Groups and Participants' Physical Activity Levels

Background: Isokinetic testing has been routinely used to assess the capacities of individual muscle groups. In this study we aimed to evaluate the sensitivity of the force-point (F-v) relationship assessed through the two-point method to discriminate between antagonist muscle groups and males with different physical activity levels. Methods: The concentric force output of the knee, hip, elbow, and shoulder flexors and extensors of 27 active and 13 non-active men was recorded at 60 and 180 degrees/s to determine the F-v relationship parameters (maximum force [F-0], maximum velocity [v(0)], and maximum power [P-max]). Results: F-0 and P-max were higher for knee extensors (effect size [ES] = 1.97 and 0.57, respectively), hip extensors (ES = 2.52 and 0.77, respectively), and shoulder flexors (ES = 1.67 and 0.83, respectively) compared to their antagonist muscles, while v(0) was higher for knee flexors compared to knee extensors (ES = 0.59). Active males revealed higher F-0 for knee extensors (ES = 0.72) and knee flexors (ES = 0.83) and higher P-max for knee flexors (ES = 0.70), elbow extensors (ES = 0.83) and shoulder extensors (ES = 0.36). Conclusions: The sensitivity of the two-point method for testing the maximal mechanical capacities was high for the knee, moderate for the hip and shoulder, and low for the elbow joint

Degenerate Domain Wall Solutions in Supersymmetric Theories

A family of degenerate domain wall configurations, partially preserving supersymmetry, is discussed in a generalized Wess-Zumino model with two scalar superfields. We establish some general features inherent to the models with continuously degenerate domain walls. For instance, for purely real trajectories additional "integrals of motion" exist. The solution for the profile of the scalar fields for any wall belonging to the family is found in quadratures for arbitrary ratio of the coupling constants. For a special value of this ratio the solution family is obtained explicitly in terms of elementary functions. We also discuss the threshold amplitudes for multiparticle production generated by these solutions. New unexpected nullifications of the threshold amplitudes are found.Comment: 21 pages, LaTeX, 3 figures using epsf.st

Coupling native page/activity-staining with SDS-PAGE/immunodetection for the analysis of glutamine synthetase isoforms in spinach

Glutamine synthetase (GS) is a key nitrogen-assimilating enzyme in plants and a target for the broad-spectrum herbicide glufosinate. Understanding its kinetic and structural properties is of major agricultural importance. Spinach (Spinacia oleracea) is classified as a plant expressing only chloroplastic GS activity. We have analyzed soluble proteins in the spinach by coupling native polyacrylamide gel electrophoresis (PAGE)-activity detection, based on phosphate precipitation, with SDS-PAGE/immunoblotting. One cytosolic (GS1) isoform from the roots and two chloroplastic (GS2) isoforms expressed in leaves were resolved by native PAGE. The identity of the obtained bands was established by the application of GS-specific inhibitors, L-methionine sulfoximine and glufosinate. Examination by sodium dodecyl sulfate (SDS)-PAGE/ Western analysis with anti-GS antibodies, confirmed the identity of the active bands and revealed that both chloroplastic isoforms are composed of 44 kDa subunits, while the cytosolic isoform consists of 40 kDa subunits. The presence of more GS2 isozymes than encoded in the spinach genome is discussed in terms of posttranslational modifications.Projekat ministarstva br. ON17302

Coupling native page/activity-staining with SDS-PAGE/immunodetection for the analysis of glutamine synthetase isoforms in spinach

Glutamine synthetase (GS) is a key nitrogen-assimilating enzyme in plants and a target for the broad-spectrum herbicide glufosinate. Understanding its kinetic and structural properties is of major agricultural importance. Spinach (Spinacia oleracea) is classified as a plant expressing only chloroplastic GS activity. We have analyzed soluble proteins in the spinach by coupling native polyacrylamide gel electrophoresis (PAGE)-activity detection, based on phosphate precipitation, with SDS-PAGE/immunoblotting. One cytosolic (GS1) isoform from the roots and two chloroplastic (GS2) isoforms expressed in leaves were resolved by native PAGE. The identity of the obtained bands was established by the application of GS-specific inhibitors, L-methionine sulfoximine and glufosinate. Examination by sodium dodecyl sulfate (SDS)-PAGE/ Western analysis with anti-GS antibodies, confirmed the identity of the active bands and revealed that both chloroplastic isoforms are composed of 44 kDa subunits, while the cytosolic isoform consists of 40 kDa subunits. The presence of more GS2 isozymes than encoded in the spinach genome is discussed in terms of posttranslational modifications.Projekat ministarstva br. ON17302

Analytic and "frozen" QCD coupling constants up to NNLO from DIS data

Deep inelastic scattering data on the F_2 structure function provided by the BCDMS, SLAC and NMC collaborations are analyzed in the non-singlet approximation with the analytic and "frozen" modifications of the strong coupling constant featuring no unphysical singularity (the Landau pole). Improvement of agreement between theory and experiment, with respect to the case of the standard perturbative definition of alpha_s considered recently, is observed and the behavior of the higher twist terms in the next-to-next-to-leading-order is found to be confirming earlier studies on the subject.Comment: 22 pp, 8 fig

Planck scale effects in neutrino physics

We study the phenomenology and cosmology of the Majoron (flavon) models of three active and one inert neutrino paying special attention to the possible (almost) conserved generalization of the Zeldovich-Konopinski-Mahmoud lepton charge. Using Planck scale physics effects which provide the breaking of the lepton charge, we show how in this picture one can incorporate the solutions to some of the central issues in neutrino physics such as the solar and atmospheric neutrino puzzles, dark matter and a 17 keV neutrino. These gravitational effects induce tiny Majorana mass terms for neutrinos and considerable masses for flavons. The cosmological demand for the sufficiently fast decay of flavons implies a lower limit on the electron neutrino mass in the range of 0.1-1 eV.Comment: 24 pages, 1 figure (not included but available upon request), LaTex, IC/92/196, SISSA-140/92/EP, LMU-09/9

Neutrino - Modulino Mixing

We suggest the existence of a light singlet fermion, $S$, which interacts with observable matter only via a Planck mass suppressed interaction: $\sim m_{3/2}/M_P$, where $m_{3/2}$ is the supergravity gravitino mass. If the mass of the singlet equals $\sim m_{3/2}^2/M_P$, then $\nu_e \to S$ resonance conversion solves the solar neutrino problem or leads to observable effects. The $\nu S$-mixing changes supernova neutrino fluxes and has an impact on the primordial nucleosynthesis. The singlet $S$ can originate as the supersymmetric partner of the moduli fields in supergravity or low energy effective theory steaming from superstrings. The $\nu S$-mixing may be accompanied by observable R-parity breaking effects.Comment: Text compressed to 4 pages and references added. Version to appear in Phys. Rev. Let

The Influence of corona on the lightninig surge propagation along transmission lines

Corona is the partial discharge that occurs around the wires and edges in inhomogeneous electric field. Minimum intensity of the electric field for the impact ionization of the gas is around 2.6 MV/m in dry air. In power systems, the corona is the unwanted effect caused by overvoltages. In this study the propagation of the overvoltage wave due to negative lightning along the transmission line is numerically simulated. The effect of the corona is modelled by the drift-diffusion-reaction equations for the electrons, the positive and the negative ions

Tesla’s high voltage and high frequency generators with oscillatory circuits

The principles that represent the basics of the work of the high voltage and high frequency generator with oscillating circuits will be discussed. Until 1891, Tesla made and used mechanical generators with a large number of extruded poles for the frequencies up to about 20 kHz. The first electric generators based on a new principle of a weakly coupled oscillatory circuits he used for the wireless signal transmission, for the study of the discharges in vacuum tubes, the wireless energy transmission, for the production of the cathode rays, that is x-rays and other experiments. Aiming to transfer the signals and the energy to any point of the surface of the Earth, in the late of 19th century, he had discovered and later patented a new type of high frequency generator called a magnifying transmitter. He used it to examine the propagation of electromagnetic waves over the surface of the Earth in experiments in Colorado Springs in the period 1899-1900. Tesla observed the formation of standing electromagnetic waves on the surface of the Earth by measuring radiated electric field from distant lightning thunderstorm. He got the idea to generate the similar radiation to produce the standing waves. On the one hand, signal transmission, i.e. communication at great distances would be possible and on the other hand, with more powerful and with at least three magnifying transmitters the wireless transmission of energy without conductors at any point of the Earth surface could also be achieved. The discovery of the standing waves on the surface of the Earth and the invention of the magnifying transmitter he claimed his greatest inventions. Less than two years later, at the end of 1901, he designed and started to build a much stronger magnifying transmitter on Long Island near New York City (the Wardenclyffe tower) wishing to become a world telecommunication center. During the tower construction, he elaborated the plans for an even stronger transmitter based on new principles. Due to lack of the funds Tesla was forced to sell or to return the devices and apparatus, he gathered in the Wardenclyffe tower facility, which intended to use to operate the tower. He left the tower in 1907 and since then he was mainly engaged in inventions that were not directly related to the electrical engineering. The unfinished magnifying transmitter on Long Island was demolished in June 1917 by the American government