905 research outputs found
Variability and polarization in the inner jet of 3C395
We present new results on the parsec-scale jet of the quasar 3C395, derived
from VLBI polarization sensitive observations made in 1995.91 and 1998.50 at
8.4, 15.4 and 22.2 GHz. The observations show a complex one-sided jet extending
up to 20 mas, with a projected magnetic field essentially aligned with the
radio jet. The emission is strongly dominated, in total intensity and
polarization, by the core and the inner jet region (of ~3 mas length). We have
studied the details of this dominant region finding clear structural variations
during this ~2.5 years period, in contrast with the apparent quietness of the
jet structure inferred from lower resolution VLBI observations. We observe the
ejection of a new component from the core and variations in the degree of
polarization of the inner jet components. We estimate a high Faraday Rotation
Measure close to the core, with a strong decrease along the inner jet.Comment: 7 pages, 4 figures, A&A in pres
VLBI observation of giant radio galaxy J1313+696 at 2.3/8.4 GHz
We report the result of VLBI observation of the giant radio galaxy J1313+696
(4C +69.15) at 2.3/8.4 GHz, only the core component of the giant radio galaxy
was detected in the VLBI observation at the dual frequencies. The result shows
a steep spectrum core with () between
2.3 GHz and 8.4 GHz. The steep spectrum core may be a sign of renewed activity.
Considering also the upper limit flux density of 2.0 mJy at 0.6 GHz from Konar
et al. 2004 the core has a GHz-peaked spectrum, implying that the core is
compact and absorbed. Further high resolution VLBI observations are needed to
identify if the steep spectrum core is consisting of a core and steep spectrum
jet.Comment: 3 pages, 3 figure
Yield and quality of ginger (Zingiber officinale Rosc.) varieties grown in Assam
Twenty indigenous and exotic varieties of ginger were evaluated for yield and quality. Significant variations in yield were observed among the varieties. Nadia yielded the highest (67.0 q/ha-fresh ginger) followed by Chekerella (57.0 qlha). Growth attributes like leaves per clump, tillers per clump and shoot height were positively correlated with yield. Moran, Jorhat hard, Thinladium and Wynad were fibrous. Moran and Jorhat hard yielded higher volatile oil and acetone extract. The fibrous varieties Moran and Jorhat hard were suitable for extraction of oleoresin and volatile oil.
 
Yield and quality of ginger (Zingiber officinale Rosc.) varieties grown in Assam
Twenty indigenous and exotic varieties of ginger were evaluated for yield and quality. Significant variations in yield were observed among the varieties. Nadia yielded the highest (67.0 q/ha-fresh ginger) followed by Chekerella (57.0 qlha). Growth attributes like leaves per clump, tillers per clump and shoot height were positively correlated with yield. Moran, Jorhat hard, Thinladium and Wynad were fibrous. Moran and Jorhat hard yielded higher volatile oil and acetone extract. The fibrous varieties Moran and Jorhat hard were suitable for extraction of oleoresin and volatile oil.
 
Time Domain Regional Discriminants
The time and frequency domains are equivalent displays of seismic trace, information, though
some qualities of the signal are more easily observed in one domain than the other. The relative
frequency excitation of Lg, for instance, is most easily viewed in the frequency domain, but such
waveform qualities as the sequence in which pulses arrive in the wave train or the sharpness of
pulse onset are most easily studied in the time domain (Murphy and Bennett, 1982, Blandford,
1981). Because of the tremendous complexity of high frequency regional data, most attempts at
using it for discrimination purposes have involved analysis of the frequency content of the various
arrivals either through transforming selected windows or through multiple bandpass filtering. We
report here on our initial attempts to explore the alternative and to discriminate events using those
waveform characteristics most easily observed in the time domain.
A second advantage of time domain analysis approaches is that they permit a deeper insight
into the physical processes creating a seismic signal's character. For this reason, they can be more
e3silv used to evaluate the transportabilty of a discriminant to varying geophysical and tectonic
regimes. This is an especially important feature in the development of regional discriminants. The
most prominent and successful spectral regional discriminants have been empirically developed.
This means that they must be redeveloped and reverified in each new area. As we shall show in
the following, through rigorous time domain analysis such features as regional depth phases can
be identified and used to discriminate. Discriminants based on such simple physical features as
source depth should be transportable anywhere.
In work recently completed under the treaty verification program, we have proved that such
time domain discriminants do exist. In analyzing a test discrimination data set from the western
U. S., we have discovered that the onset of P_n is always very similar for explosions and that few
earthquakes have this unique waveform character. This information can be constructed into a
simple discrimination scheme by testing the correlation of observed P_n waveform onsets with
average waveforms observed from explosions. High correlations indicate explosions and low
correlations earthquakes. We have also discovered that the regional phase P_g is actually composed of a sequence of sub-arrivals which correspond to successively higher orders of reverberation in
the crust. In realistic crust models, the depth phases play an important role in the waveshapes of
these sub-arrivals. By selecting an appropriate frequency band to analyze, we have been able to
accurately model this type of data from explosions in the western United States. Over the very
relevant regional distance ranges of 200 to 600 km, it appears that a discrimination procedure very
similar to the one which is known to work for P_n will also be effective for P_g. We are investigating
whether similar discriminants can be constructed based on the phases S_n and S_g in areas where
those phases are prominent arrivals
Nuclear spirals as feeding channels to the Supermassive Black Hole: the case of the galaxy NGC 6951
We report the discovery of gas streaming motions along nuclear spiral arms
towards the LINER nucleus of the galaxy NGC 6951. The observations, obtained
using the GMOS integral field spectrograph on the Gemini North telescope,
yielded maps of the flux distributions and gas kinematics in the Halpha,
[NII]6584 and [SII]6717,31 emission lines of the inner 7x5 arcsec^2 of the
galaxy. This region includes a circumnuclear star-forming ring with radius
500pc, a nuclear spiral inside the ring and the LINER nucleus. The kinematics
of the ionized gas is dominated by rotation, but subtraction of a kinematic
model of a rotating exponential disk reveals deviations from circular rotation
within the nuclear ring which can be attributed to (1) streaming motions along
the nuclear spiral arms and (2) a bipolar outflow which seems to be associated
to a nuclear jet. On the basis of the observed streaming velocities and
geometry of the spiral arms we estimate a mass inflow rate of ionized gas of
3x10^(-4) Msun/yr, which is of the order of the accretion rate necessary to
power the LINER nucleus of NGC 6951. Similar streaming motions towards the
nucleus of another galaxy with LINER nucleus -- NGC 1097 -- have been reported
by our group in a previous paper. Taken together, these results support a
scenario in which nuclear spirals are channels through which matter is
transferred from galactic scales to the nuclear region to feed the supermassive
black hole.Comment: 25 pages, 6 eps figures, accepted for publication in Ap
Time Domain Regional Discriminants
The time and frequency domains are equivalent displays of seismic trace, information, though
some qualities of the signal are more easily observed in one domain than the other. The relative
frequency excitation of Lg, for instance, is most easily viewed in the frequency domain, but such
waveform qualities as the sequence in which pulses arrive in the wave train or the sharpness of
pulse onset are most easily studied in the time domain (Murphy and Bennett, 1982, Blandford,
1981). Because of the tremendous complexity of high frequency regional data, most attempts at
using it for discrimination purposes have involved analysis of the frequency content of the various
arrivals either through transforming selected windows or through multiple bandpass filtering. We
report here on our initial attempts to explore the alternative and to discriminate events using those
waveform characteristics most easily observed in the time domain.
A second advantage of time domain analysis approaches is that they permit a deeper insight
into the physical processes creating a seismic signal's character. For this reason, they can be more
e3silv used to evaluate the transportabilty of a discriminant to varying geophysical and tectonic
regimes. This is an especially important feature in the development of regional discriminants. The
most prominent and successful spectral regional discriminants have been empirically developed.
This means that they must be redeveloped and reverified in each new area. As we shall show in
the following, through rigorous time domain analysis such features as regional depth phases can
be identified and used to discriminate. Discriminants based on such simple physical features as
source depth should be transportable anywhere.
In work recently completed under the treaty verification program, we have proved that such
time domain discriminants do exist. In analyzing a test discrimination data set from the western
U. S., we have discovered that the onset of P_n is always very similar for explosions and that few
earthquakes have this unique waveform character. This information can be constructed into a
simple discrimination scheme by testing the correlation of observed P_n waveform onsets with
average waveforms observed from explosions. High correlations indicate explosions and low
correlations earthquakes. We have also discovered that the regional phase P_g is actually composed of a sequence of sub-arrivals which correspond to successively higher orders of reverberation in
the crust. In realistic crust models, the depth phases play an important role in the waveshapes of
these sub-arrivals. By selecting an appropriate frequency band to analyze, we have been able to
accurately model this type of data from explosions in the western United States. Over the very
relevant regional distance ranges of 200 to 600 km, it appears that a discrimination procedure very
similar to the one which is known to work for P_n will also be effective for P_g. We are investigating
whether similar discriminants can be constructed based on the phases S_n and S_g in areas where
those phases are prominent arrivals
Antioxidant activity, phenol and flavonoid content of A.racemosus Willd. a medicinal plant grown using different organic manures
ABSTRACT Antioxidant activity, phenol and flavonoid content were determined in the ethanol extract of roots of Asparagus racemosus grown under organic regime in the Experimental Garden of the Life Sciences Department, Dibrugarh University, Assam, during three consecutive years 2007 to 2010. Organic regimes were provided by treating the soil with bulky organic manures-cowdung, compost, and vermicompost without using mineral or chemical fertilizer. The roots were harvested from 18 months old plants and subjected to estimation of phenol and flavonoid content, and for antioxidant activities. Total phenol and flavonoid content and DPPH radical scavenging activity of the extracts were spectrophotometrically determined. Catechol, Quercetin, and ascorbic acid were taken as standard in case of phenol, flavonoid content and antioxidant activity respectively. The total phenol and total flavonoid content was highest in the plants from vermicompost treated soil. The DPPH radical scavenging activity was highest in the plants from compost treated soil. There observed a relationship between phenol and flavonoid content but failed to show relationship between phenolic content and antioxidant activity of the ethanol extracts of the plants grown in different organic regimes. Effect of growing conditions on production of secondary metabolites by medicinal plants has been revealed by the present study
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