7,387 research outputs found
Assistance to farmer-managed irrigation system: Experiences from Nepal - Papers presented in the seminar on "Improving Farmer Managed Irrigation Systems: Experiences of different agencies and organizations" held on 27 June 1990
Farmer managed irrigation systems / Governmental interrelations / Development aid / Nepal
Biodesulfurization of dibenzothiophene by Shewanella putrefaciens NCIMB 8768
The desulfurization ability of Shewanella putrefaciens strain NCIMB 8768 was
studied and its activity profile was compared with the widely studied strain
Rhodococcus erythropolis strain IGTS8. Dibenzothiophene (DBT) is a recalcitrant
thiophenic component of fossil fuels especially among diesel blend stocks. DBT
in basic salt medium (BSM) at a final concentration of 0.3, 0.6 and 0.9 mM was
supplied to the microbes as the sole sulfur source. Experimental results showed
that S. putrefaciens, similar to other biodesulfurization organisms, converted
DBT to the end product 2-hydroxybiphenyl (HBP), as detected by the Gibbs assay
and HPLC. Cells cultivated in medium containing 0.3 mM of DBT showed the highest
desulfurization activity, with a maximum specific production rate 43.5 mmol/L of
HBP
A new class of two-channel biorthogonal filter banks and wavelet bases
We propose a novel framework for a new class of two-channel biorthogonal filter banks. The framework covers two useful subclasses: i) causal stable IIR filter banks. ii) linear phase FIR filter banks. There exists a very efficient structurally perfect reconstruction implementation for such a class. Filter banks of high frequency selectivity can be achieved by using the proposed framework with low complexity. The properties of such a class are discussed in detail. The design of the analysis/synthesis systems reduces to the design of a single transfer function. Very simple design methods are given both for FIR and IIR cases. Zeros of arbitrary multiplicity at aliasing frequency can be easily imposed, for the purpose of generating wavelets with regularity property. In the IIR case, two new classes of IIR maximally flat filters different from Butterworth filters are introduced. The filter coefficients are given in closed form. The wavelet bases corresponding to the biorthogonal systems are generated. the authors also provide a novel mapping of the proposed 1-D framework into 2-D. The mapping preserves the following: i) perfect reconstruction; ii) stability in the IIR case; iii) linear phase in the FIR case; iv) zeros at aliasing frequency; v) frequency characteristic of the filters
On the one-loop correction of "phi^4" theory in higher dimensions
We have considered phi^4 theory in higher dimensions. Using functional
diagrammatic approach, we computed the one-loop correction to effective
potential of the scalar field in five dimensions. It is shown that phi^4 theory
can be regularised in five dimensions. Temperature dependent one-loop
correction and critical temperature T_c are computed and T_c depends on the
fundamental scale M of the theory. A brief discussion of symmetry restoration
is also presented. The nature of phase transitions is examined and is of second
orderComment: 8 pages, 5 figures. To appear in IJMP
Improved Detection Rates for Close Binaries Via Astrometric Observations of Gravitational Microlensing Events
In addition to constructing a Galactic matter mass function free from the
bias induced by the hydrogen-burning limit, gravitational microlensing allows
one to construct a mass function which is less affected by the problem of
unresolved binaries (Gaudi & Gould). However, even with the method of
microlensing, the photometric detection of binaries is limited to binary
systems with relatively large separations of of their combined
Einstein ring radius, and thus the mass function is still not totally free from
the problem of unresolved binaries. In this paper, we show that by detecting
distortions of the astrometric ellipse of a microlensing event with high
precision instruments such as the {\it Space Interferometry Mission}, one can
detect close binaries at a much higher rate than by the photometric method. We
find that by astrometrically observing microlensing events, of
binaries with separations of can be detected with the detection
threshold of 3%. The proposed astrometric method is especially efficient at
detecting very close binaries. With a detection threshold of 3% and a rate of
10%, one can astrometrically detect binaries with separations down to .Comment: total 14 pages, including 5 Figures and no Table (For figure 1,
please send a request mail to [email protected]), accepted to
ApJ (Vol 525, 000), updated versio
Microlensing Surveys of M31 in the Wide Field Imaging Era
The Andromeda Galaxy (M31) is the closest large galaxy to the Milky Way, thus
it is an important laboratory for studying massive dark objects in galactic
halos (MACHOs) by gravitational microlensing. Such studies strongly complement
the studies of the Milky Way halo using the the Large and Small Magellanic
Clouds. We consider the possibilities for microlensing surveys of M31 using the
next generation of wide field imaging telescopes with fields of view in the
square degree range. We consider proposals for such imagers both on the ground
and in space. For concreteness, we specialize to the SNAP proposal for a space
telescope and the LSST proposal for a ground based telescope. We find that a
modest space-based survey of 50 visits of one hour each is considerably better
than current ground based surveys covering 5 years. Crucially, systematic
effects can be considerably better controlled with a space telescope because of
both the infrared sensitivity and the angular resolution. To be competitive, 8
meter class wide-field ground based imagers must take exposures of several
hundred seconds with several day cadence.Comment: 10 pages, 4 figures, 2 table
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The autoepitope of the 74-kD mitochondrial autoantigen of primary biliary cirrhosis corresponds to the functional site of dihydrolipoamide acetyltransferase.
Autoantibodies to mitochondrial antigens are characteristic of the autoimmune liver disease primary biliary cirrhosis (PBC), but the precise antigenic determinants recognized by these antibodies have not been defined. Recently, our laboratory identified a 1,370-bp rat liver cDNA clone that coded for a polypeptide recognized specifically by sera from patients with PBC but not by sera from patients with other forms of liver disease. This recombinant protein was identified as the 74-kD M2 mitochondrial inner membrane autoantigen, now known to be dihydrolipoamide acetyltransferase. In the present study, we have identified a 603-bp fragment that codes for a polypeptide containing all of the autoreactivity of the original clone. In addition, based on hydrophobicity/hydrophilicity plots of the amino acid sequence of this polypeptide segment, several peptides were synthesized and tested for reactivity by an inhibition assay using sera from patients with PBC. One peptide, defined by the amino acids AEIETDKATIGFEVQEEGYL, absorbed serum reactivity to the protein product of the original clone. Of particular interest was the finding that this peptide contains the lipoic acid binding site KATIGF of the dihydrolipoamide acetyltransferase found in the inner mitochondrial membrane. Thus, it appears that for this autoantigen, the target of the autoantibodies corresponds to a functional site of the dihydrolipoamide acetyltransferase
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