Ionization effects due to solar flare on terrestrial ionosphere

Sudden frequency deviation ionospheric disturbances related to the flares of May 18 and 19, 1973 were observed from the NASA/MSFC high frequency Doppler sounder array system in Huntsville, Alabama. The results are compared with those observed at Table Mountain near Boulder, Colorado and at the University of Hawaii

Valley filter in strain engineered graphene

We propose a simple, yet highly efficient and robust device for producing valley polarized current in graphene. The device comprises of two distinct components; a region of uniform uniaxial strain, adjacent to an out-of-plane magnetic barrier configuration formed by patterned ferromagnetic gates. We show that when the amount of strain, magnetic field strength, and Fermi level are properly tuned, the output current can be made to consist of only a single valley contribution. Perfect valley filtering is achievable within experimentally accessible parameters.Comment: 4 pages, 3 figures; minor corrections, updated Figs. 2 and 3, added reference

Risk Quotient of Airborne Paraquat Exposure Among Workers in Palm Oil Plantation

Paraquat is the herbicide widely used at palm oil plantations, although usage it in some countries has been banned and restricted. Paraquat spraying was not appropriate procedure could be polluted the environment and lead to health disorders workers. Paraquat could enter the body through inhalation, dermal and ingestion, one of frequent routes through inhalation during spraying weeds in plantation areas. This study aimed was to analyze potential inhalation dose and Risk Quotient to workers at palm oil plantation. This research was a descriptive study with cross sectional design and analysis of environmental health risk methods. Airborne Paraquat residue was collected from 8 workers with occupational activity as a supervisor and sprayer. Airborne Paraquat residue was measured for 25 minutes during spraying by using personal air sampler at worker's breathing zone. Airborne Paraquat residue was detected by High Performance Liquid Chromatography (HPLC) with NIOSH 5003 methods. The average of airborne Paraquat residue was 0.0125 mg/m3, it values was less than the Threshold Limit Value (0.05 mg/m3) of American Conference of Government Industrial Hygienists, but the average of potential inhalation dose was 0.001 mg/kg/day for worker's weight 55 kg, it was value higher than Acceptable Operator Exposure Limit (0.0005 mg/kg/day) and the calculation of Risk Quotient (RQ) was more than 1, it conditions was unacceptable for workers. Although, airborne Paraquat residue were safe, but potential inhalation dose and Risk Quotient (RQ) were unsafe for workers, cause it can be lead to lung function disorders. Therefore, for further studies it was necessary to assess the lung function of workers and the use of personal protective equipment must be completely and standard

Observations of HONO by laser-induced fluorescence at the South Pole during ANTCI 2003

Observations of nitrous acid (HONO) by laser-induced fluorescence (LIF) at the South Pole taken during the Antarctic Troposphere Chemistry Investigation (ANTCI), which took place over the time period of Nov. 15, 2003 to Jan. 4, 2004, are presented here. The median observed mixing ratio of HONO 10 m above the snow was 5.8 pptv (mean value 6.3 pptv) with a maximum of 18.2 pptv on Nov 30th, Dec 1st, 3rd, 15th, 17th, 21st, 22nd, 25th, 27th and 28th. The measurement uncertainty is ±35%. The LIF HONO observations are compared to concurrent HONO observations performed by mist chamber/ion chromatography (MC/IC). The HONO levels reported by MC/IC are about 7.2 ± 2.3 times higher than those reported by LIF. Citation: Liao, W., A. T. Case, J. Mastromarino, D. Tan, and J. E. Dibb (2006), Observations of HONO by laser-induced fluorescence at the South Pole during ANTCI 2003, Geophys. Res. Lett., 33, L09810, doi:10.1029/2005GL025470

Semi-classical States in Homogeneous Loop Quantum Cosmology

Semi-classical states in homogeneous loop quantum cosmology (LQC) are constructed by two different ways. In the first approach, we firstly construct an exponentiated annihilation operator. Then a kind of semi-classical (coherent) state is obtained by solving the eigen-equation of that operator. Moreover, we use these coherent states to analyze the semi-classical limit of the quantum dynamics. It turns out that the Hamiltonian constraint operator employed currently in homogeneous LQC has correct classical limit with respect to the coherent states. In the second approach, the other kind of semi-classical state is derived from the mathematical construction of coherent states for compact Lie groups due to Hall.Comment: 13 pages, submitted to CQ