1,619 research outputs found

    Is HE 0436-4717 Anemic? A deep look at a bare Seyfert 1 galaxy

    Get PDF
    A multi-epoch, multi-instrument analysis of the Seyfert 1 galaxy HE 0436-4717 is conducted using optical to X-ray data from XMM-Newton and Swift (including the BAT). Fitting of the UV-to-X-ray spectral energy distribution shows little evidence of extinction and the X-ray spectral analysis does not confirm previous reports of deep absorption edges from OVIII. HE 0436-4717 is a "bare" Seyfert with negligible line-of-sight absorption making it ideal to study the central X-ray emitting region. Three scenarios were considered to describe the X-ray data: partial covering absorption, blurred reflection, and soft Comptonization. All three interpretations describe the 0.5-10.0 keV spectra well. Extrapolating the models to 100 keV results in poorer fits for the the partial covering model. When also considering the rapid variability during one of the XMM-Newton observations, the blurred reflection model appears to describe all the observations in the most self-consistent manner. If adopted, the blurred reflection model requires a very low iron abundance in HE 0436-4717. We consider the possibilities that this is an artifact of the fitting process, but it appears possible that it is intrinsic to the object.Comment: 7 tables, 11 figures, 16 pages; accepted for publication in MNRAS 17 Feb. 201

    Electrolytic preparation of magnesium perchlorate

    Get PDF
    The electrochemical preparation of magnesium perchlorate from magnesium chlorate employing a platinum anode and a rotating stainless steel cathode is described. The effect of electrolyte con,=en-tration, cathode and anode current densities, pH and temperature of the electrolyte and cathode rotation on current efficiency for the preparation of magnesium perchlorate was studied. A maximum curren t efficiency of 65-72% was achieved. Based on the results obtained on the laboratory scale, a 100A cell was designed, fabricated and operated

    Circularly Polarised Hexagonal Patch Antenna With Polygonal Slot for RFID Applications

    Get PDF
    A compact single feed circularly polarized microstrip patch antenna for RFID applications is proposed. Antenna geometry includes a regular hexagon shaped patch with a polygonal slot embedded at the centre. The slot accounts for circular polarization and an area reduction of 22.5 %. It is fabricated on FR4 substrate with dielectric constant 4.4 and size 50 mm x 50 mm x 1.6 mm. The measured results include 10dB impedance bandwidth of 5.5 % at the center frequency of 2.42 GHz, a return loss of 32 dB, minimum axial ratio of 1.82 dB, axial ratio bandwidth of 7.5%, gain of 4.9 dBi with a broadside radiation characteristic for the RHCP antenna. These results are well in tune with the simulated results and the proposed design is suitable for RFID reader antenna applications

    Grating-based Dipole Antenna Configuration for High Gain Directional Radiation characteristics

    Get PDF
    The experimental and simulation studies of the radiation performance enhancement of a dipole antenna using metal strip grating are presented in this paper. The subwavelength imaging configuration of the metal strip grating is utilized for enhancing the radiation performance of a dipole antenna working in the S-band. The resultant design shows a gain of 9 dBi and front to back ratio of the design is found to be -23 dB at resonance. The coupling between electric and magnetic resonances provides the necessary impedance matching performance when the antenna is brought in the vicinity of the grating

    Grating-based Dipole Antenna Configuration for High Gain Directional Radiation characteristics

    Get PDF
    The experimental and simulation studies of the radiation performance enhancement of a dipole antenna using metal strip grating are presented in this paper. The subwavelength imaging configuration of the metal strip grating is utilized for enhancing the radiation performance of a dipole antenna working in the S-band. The resultant design shows a gain of 9 dBi and front to back ratio of the design is found to be -23 dB at resonance. The coupling between electric and magnetic resonances provides the necessary impedance matching performance when the antenna is brought in the vicinity of the grating

    Cisgenics and intragenics: boon or bane for crop improvement

    Get PDF
    Recent advances in molecular biology and genetic engineering have made it possible to increase agricultural yields when compared to conventional methods. However, lots of challenges are to be addressed due to changing climatic conditions. Although genetically modified organisms (GMOs) have proven their potential in a few crops, but needs to be explored in majority of the field/vegetable crops to overcome food and nutritional security in view of alarming population explosion. In spite of advantages from GMO crops due to the presence of foreign DNA, queries regarding their safety, environmental dangers and health effects needs to be addressed. One of the major environmental issues concerning transgenic crops is the mixing of genetic components across species that cannot hybridize naturally. Due to these limitations, new revolutionary technologies have been developed, such as intragenesis and cisgenesis for the transformation and development of superior plants. While cisgenesis entails genetic modification employing a complete copy of natural genes with their native regulatory components that only belong to sexually compatible species, intragenesis refers to the transfer of unique combinations of genes and regulatory sequence inside the same species. In cisgenesis, the donor genes are the same genes employed in conventional breeding. The two benefits of cisgenics are avoiding linkage drag and making greater use of existing gene alleles. This method significantly shortens the time it takes to breed plants by combining conventional methods with cutting-edge biotechnological tools. Because of this, plant genomes can be altered without causing drastic changes to the whole plant population and the environmental effects of cisgenic plants cannot be compared to those of transgenics. Transgenesis and cisgenesis share the same transformation methods; hence, cisgenic, intragenic and transgenic plants produced through random insertion do not pose any distinct risks with regard to host genome modifications. In contrast, using new genome techniques lessens the dangers related to potential unintentional changes to the host DNA. The use of cisgenesis and intragenesis as alternatives to transgenesis has been restricted to a small number of species due to incomplete understanding of the required regulatory sequences

    Finite Schur filtration dimension for modules over an algebra with Schur filtration

    Full text link
    Let G be GL_N or SL_N as reductive linear algebraic group over a field k of positive characteristic p. We prove several results that were previously established only when N 2^N. Let G act rationally on a finitely generated commutative k-algebra A. Assume that A as a G-module has a good filtration or a Schur filtration. Let M be a noetherian A-module with compatible G action. Then M has finite good/Schur filtration dimension, so that there are at most finitely many nonzero H^i(G,M). Moreover these H^i(G,M) are noetherian modules over the ring of invariants A^G. Our main tool is a resolution involving Schur functors of the ideal of the diagonal in a product of Grassmannians.Comment: 22 pages; final versio
    corecore