Metamaterial With Local Resonators Coupled by Negative Stiffness Springs for Enhanced Vibration Suppression

In recent years, metamaterials for the applications in low-frequency vibration suppression and noise reduction have attracted numerous research interests. This paper proposes a metamaterial system with local resonators from adjunct unit cells coupled by negative stiffness springs. Frist, a lumped parameter model of the system is developed, and a stability criterion is derived. The band structure of the infinite lattice model is calculated. The result reveals the appearance of extra band gaps in the proposed metamaterial. A parametric study shows that the first extra band gap can be tuned to ultralow frequency by controlling the negative stiffness of the coupling springs. A transmittance analysis of the finite lattice model verifies the predictions obtained from the band structure analysis. Subsequently, the work is extended to a distributed parameter metamaterial beam model with the proposed configuration of coupled local resonators. The stability analysis shows that the infinitely long metamaterial beam becomes unstable as long as the stiffness of the coupling spring becomes negative. For the finitely long metamaterial beam, the stability could be achieved for negative coupling springs of given stiffnesses. The effects of the number of cells and the lattice constant on the system stability are investigated. The transmittance of the finitely long metamaterial beam is calculated. The result shows that due to the restriction on the tunability of negative stiffness for the proposed metamaterial beam, a quasistatic vibration suppression region can only be achieved when the number of cells is small.

MIMO Channel Research and Hardware Implementation

The MIMO technology, namely through many antenna clear signal transmission and the receive, in does not increase the extra band width under the premise, enhanced the channel capacity greatly. Understood the MIMO channel the characteristic, studies the channel modelling method, unified the FPGA parallel characteristic, the design has manufactured one kind based on XILINX FPGA the platform MIMO channel analog meter, through the massive test confirmation, and did with the theoretically simulation performance compares, has confirmed the accuracy.

Influence of IAA, kinetin and ABA on ribonuclease activity in the embryonal roots of two barley (Hordeum vulgare L.) cultivars

IAA, kinetin and ABA in a concentration of 10^-7M did not cause major changes in the activity of ribonuclease in both cultivars. IAA and kinetin in a concentration of 10^-5M lowered the activity of the tested enzyme, more in the 'Union' than in the 'Lubuski' cultivar. ABA in a concentration of 10^-5M did not change the activity of ribonuclease in both cultivars. It caused, however, the appearance of an extra band with ribonuclease activity on the polyacrylamide gel in both cultivars.

Two Nonsense Mutations of PAX6 in Two Japanese Aniridia Families: Case Report and Review of the Literature

Purpose To identify PAX6 mutations in patients from four Japanese families with aniridia. Methods Polymerase chain reaction (PCR)-single stand conformational polymorphism (SSCP) analysis (SSCA) was performed in probands of the families, and restriction analysis using MaeIII or AvaI was carried out in other affected family members. Results PCR-SSCA demonstrated in the proband from one family an extra-band in the PCR product for PAX6 exon 8. Base sequence analysis revealed that the patient is a heterozygote for a C to T transition mutation at codon 203. DNAs from the patient and another affected member in the same family were cut with MaeIII into two fragments, while non-affected members in the family showed only one MaeIII fragment, the result confirmed the mutation. In another family, PCR-SSCA revealed an extra-band in the PCR product for exon 9. Sequencing detected a C→T substitution at codon 240 in the patient, the mutation resulted in loss of an AvaI site. AvaI cleavage analysis confirmed the mutation in the patient. The two transition mutations observed in the two families also predict the conversion of arginine to a stop codon (R203X and R240X, respectively) around the homeodomain (HD), leading to the truncation of the PAX6 protein within its glycine-rich region. No abnormal SSCP bands or abnormal restriction fragments were detected in patients from the other two families. Conclusions The two mutations sites identified in the two families, one at codon 203 and the other at codon 240, are those most frequently observed among 118 previously reported PAX6 mutations. This indicates that the two mutations are two hot-spots in the gene.