Observation of modulation instability in a nonlinear magnetoinductive waveguide

We report numerical and experimental investigations into modulation instability in a nonlinear magnetoinductive waveguide. By numerical simulation we find that modulation instability occurs in an electrical circuit model of a magnetoinductive waveguide with third-order nonlinearity. We fabricate the nonlinear magnetoinductive waveguide for microwaves using varactor-loaded split-ring resonators and observe the generation of modulation instability in the waveguide. The condition for generating modulation instability in the experiment roughly agrees with that in the numerical analysis.Comment: 7 pages, 11 figure

Enhancement of second harmonic generation in a doubly resonant metamaterial

We investigate second harmonic (SH) generation in a doubly resonant metamaterial. We show that SH generation can be enhanced when the resonant condition is satisfied for the SH frequency as well as for the fundamental frequency. A unit cell of the doubly resonant metamaterial consists of two coupled resonators, one of which resonates at the fundamental frequency, whereas the other resonates around the SH frequency. We observe that the SH generation in the doubly resonant metamaterial is 4.6 times as large as that in a singly resonant metamaterial.Comment: 4 pages, 4 figure

Detection of Molecular Clouds in the Interarm of the Flocculent Galaxy NGC 5055

We present high-resolution (~ 4") 12CO (J = 1 - 0) mapping observations with high - velocity resolution (~ 2.6 km s^{-1}) toward the disk of flocculent galaxy NGC 5055, using the Nobeyama Millimeter Array in order to study the physical properties of the molecular clouds in the arm and the interarm. The obtained map shows clumpy structures. Although these are mainly distributed along a spiral arm seen in near-infrared observations, some clouds are located far from the arm, namely in the interarm. These clouds in both the arm and the interarm have a typical size and mass of a few 100 pc and a few 10^6 Mo, respectively. These correspond to the largest Giant Molecular Cloud (GMC) in our Galaxy, and are slightly smaller than Giant Molecular Associations (GMAs) in the grand design spiral M 51. Their CO flux-based masses show good agreement with their virial masses. A size - velocity dispersion relation is also plotted on an extension of the relation for the Galactic GMCs. These facts suggest that the properties of these clouds are similar to that of the Galactic GMCs. We also found no clear systematic offset between the molecular gas and HII regions unlike M 51. This fact and no existense of GMAs suggest the view that, in NGC 5055, cloud formation and following star formation in both the arm and the interarm are due to enhancement of gas by local fluctuation. On the other hand, in grand design spiral galaxies, such as M 51, GMA formations may occur only in the arm due to a strong density wave also enhanced star formation in GMA formation may also occur. These may control the optical morphology of spiral arms in spiral galaxies.Comment: 16 pages, 8 figure

Nitrogen Fixation and Translocation in Sugarcane

World sugarcane production is increasing rapidly as a biofuel. In some areas in Brazil, sugarcane has been grown continually over very long periods without N fertiliser inputs. Therefore, the occurrence of N fixation has been suspected. However, quantitative studies seeking to identify the N~2~ fixation sites in the plant and to record the translocation of fixed N around the plant have not yet established. A ^15^N~2~ gas tracer experiment was conducted using young sugarcane plants to investigate the sites of N~2~ fixation and also to explore the possibility of translocation of the fixed N among the plant's major organs. Young sugarcane plants (_Saccharum officinarum_ L.) about 40 cm high and some 14 days after sprouting from a stem cutting were exposed to ^15^N~2~ labeled air in a 500 mL plastic cylinder for 7 days. Following the 7-day ^15^N~2~ feeding, some plants were potted and grown on in normal air for a further chase period. The incorporation of ^15^N into the shoot, roots, and stem cutting was analysed at day-3, and day-7 of the labeling period and at day-14, and day-21 during the chase period. After 3 days of ^15^N~2~ feeding, the % of N derived from the ^15^N labeled air in the shoot, roots and stem cutting were 0.027%, 2.22% and 0.271%, respectively. The roots showed the highest N fixing activity followed by the stem cutting, while the incorporation of ^15^N into the shoot was very low. After 21 days about a half of the N originating in the stem cutting had been transported to the shoot and the roots. However, the ^15^N fixed either in the roots or in the stem cutting remained in the original parts and was not appreciably transported to the shoot