3,682 research outputs found
Method of characteristics and solution of DGLAP evolution equation in leading order (LO) and next to leading order (NLO) at small-x
In this paper the singlet and non-singlet structure functions have been
obtained by solving Dokshitzer, Gribove, Lipatov, Alterelli, Parisi (DGLAP)
evolution equations in leading order (LO) and next to leading order (NLO) at
the small x limit. Here we have used a Taylor Series expansion and then the
method of characteristics to solve the evolution equations. We have also
calculated t and x-evolutions of deuteron structure function and the results
are compared with the New Muon Collaboration (NMC) data.Comment: 16 pages including 7 figure
Plasmons in coupled bilayer structures
We calculate the collective charge density excitation dispersion and spectral
weight in bilayer semiconductor structures {\it including effects of interlayer
tunneling}. The out-of-phase plasmon mode (the ``acoustic'' plasmon) develops a
long wavelength gap in the presence of tunneling with the gap being
proportional to the square root (linear power) of the tunneling amplitude in
the weak (strong) tunneling limit. The in-phase plasmon mode is qualitatively
unaffected by tunneling. The predicted plasmon gap should be a useful tool for
studying many-body effects.Comment: 10 pages, 6 figures. to appear in Phys. Rev. Let
Dissipationless transport in low density bilayer systems
In a bilayer electronic system the layer index may be viewed as the
z-component of an isospin-1/2. An XY isospin-ordered ferromagnetic phase was
observed in quantum Hall systems and is predicted to exist at zero magnetic
field at low density. This phase is a superfluid for opposite currents in the
two layers. At B=0 the system is gapless but superfluidity is not destroyed by
weak disorder. In the quantum Hall case, weak disorder generates a random gauge
field which probably does not destroy superfluidity. Experimental signatures
include Coulomb drag and collective mode measurements.Comment: 4 pages, no figures, submitted to Phys. Rev. Let
Methods for the estimation of pyrazinamide and pyrazinoic acid in body fluids
zinoic
acid in urine using an anion-exchange resin (Dowex-1) have been described.
Recoveries were quantitative, and the sensitivity was 5 μg/ml for ail 3 estimations.
In serum, pyrazinoic acid at a concentration of 50 μg/ml did not interfere with the
estimation of pyrazinamide. In urine, pyrazinamide and pyrazinoic acid could
be separated from each other and estimated even when the 2 compounds were
present together at concentrations of 2000 μg/ml each
Climate Resilient Agriculture Experiences from NICRA Implementation in North Bank Plains Zone of Assam
Not AvailableClimate change impacts on agriculture are being witnessed all over the world, but
countries like India are more vulnerable in view of the huge population dependent on
agriculture, excessive pressure on natural resources and poor coping mechanisms. The
warming trend in India over the past 100 years has indicated an increase of 0.60°C. The
projected impacts are likely to further aggravate field fluctuations of many crops thus
impacting food security. There are already evidences of negative impacts on yield of wheat
and paddy in parts of India due to increased temperature, water stress and reduction in
number of rainy days. Increased abnormalities in amount and distribution of rainfall has also
been observed in North Bank Plains Zone (NBPZ) of Assam along with increase in numbers
of wet spell driven flash floods and seasonal droughts in recent years.
Planned adaption is essential to increase the resilience of agricultural production to
climate change. Several improved agricultural practices evolved over time for diverse agroecological
regions in India have potential to enhance climate change adaptation, if deployed
prudently. Management practices that increase agricultural production under adverse climatic
conditions also tend to support climate change adaptation because they increase resilience
and reduce yield variability under variable climate and extreme events.
Keeping this in view, National Innovations on Climate Resilient Agriculture was
implemented under All India Coordinated Research Project for Dryland Agriculture,
Biswanath Chariali centre on 2011in two selected villages of North Lakhimpur, Chamua and
Ganakdoloni. The main aim of the project is to enhance resilience of Indian agriculture to
climate change and climate variability through strategic research and technology
demonstration.
In this bulletin the authors have penned down the experiences gained from
implementation of NICRA in NBPZ of Assam. It is hoped that the bulletin will be able to
serve the purposes towards achieving its objectives and act as a benchmark study for the
entire area. It is expected that the information contained in this bulletin will be exploited by
the scientist of different disciplines and extension officials for making rational
recommendation.
The authors will remain ever grateful to Project Coordinator, (AICRPDA), CRIDA,
Hyderabad and Director of Research (Agri), AAU for their guidance, encouragement and
sincere support. The authors extend thankfulness to the fellow Scientists, Research
Associates and other technical staff for their cooperation and help. The authors express their
thankfulness to Sharada Offset, Biswanath Chariali for printing the report.Not Availabl
Hall state quantization in a rotating frame
We derive electromagnetomotive force fields for charged particles moving in a
rotating Hall sample, satisfying a twofold U(1) gauge invariance principle. It
is then argued that the phase coherence property of quantization of the line
integral of total collective particle momentum into multiples of Planck's
quantum of action is solely responsible for quantization in the Hall state. As
a consequence, the height of the Hall quantization steps should remain
invariant in a rapidly rotating Hall probe. Quantum Hall particle
conductivities do not depend on charge and mass of the electron, and are
quantized in units of the inverse of Planck's action quantum.Comment: 6 pages, accepted for publication in Europhysics Letter
Possible evidence of non-Fermi liquid behavior from quasi-one-dimensional indium nanowires
We report possible evidence of non-Fermi liquid (NFL) observed at room
temperature from the quasi one-dimensional (1D) indium (In) nanowires
self-assembled on Si(111)-77 surface. Using high-resolution
electron-energy-loss spectroscopy, we have measured energy and width
dispersions of a low energy intrasubband plasmon excitation in the In
nanowires. We observe the energy-momentum dispersion (q) in the low q
limit exactly as predicted by both NFL theory and the
random-phase-approximation. The unusual non-analytic width dispersion measured with an exponent =1.400.24, however,
is understood only by the NFL theory. Such an abnormal width dispersion of low
energy excitations may probe the NFL feature of a non-ideal 1D interacting
electron system despite the significantly suppressed spin-charge separation
(40 meV).Comment: 11 pages and 4 figure
Quantum-Classical Crossover and Apparent Metal-Insulator Transition in a Weakly Interacting 2D Fermi Liquid
We report the observation of a parallel magnetic field induced
metal-insulator transition (MIT) in a high-mobility two-dimensional electron
gas (2DEG) for which spin and localization physics most likely play no major
role. The high-mobility metallic phase at low field is consistent with the
established Fermi liquid transport theory including phonon scattering, whereas
the insulating phase at higher field shows a large negative temperature
dependence at resistances much smaller than the quantum of resistance, .
We argue that this observation is a direct manifestation of a quantum-classical
crossover arising predominantly from the magneto-orbital coupling between the
finite width of the 2DEG and the in-plane magnetic field.Comment: 4 pages, 2 figure
Generalized survival in equilibrium step fluctuations
We investigate the dynamics of a generalized survival probability
defined with respect to an arbitrary reference level (rather than the
average) in equilibrium step fluctuations. The exponential decay at large time
scales of the generalized survival probability is numerically analyzed.
is shown to exhibit simple scaling behavior as a function of
system-size , sampling time , and the reference level . The
generalized survival time scale, , associated with is shown
to decay exponentially as a function of .Comment: 4 pages, 2 figure
Contrasting Behavior of the 5/2 and 7/3 Fractional Quantum Hall Effect in a Tilted Field
Using a tilted field geometry, the effect of an in-plane magnetic field on
the even denominator nu = 5/2 fractional quantum Hall state is studied. The
energy gap of the nu = 5/2 state is found to collapse linearly with the
in-plane magnetic field above ~0.5 T. In contrast, a strong enhancement of the
gap is observed for the nu = 7/3 state. The radically distinct tilted-field
behaviour between the two states is discussed in terms of Zeeman and
magneto-orbital coupling within the context of the proposed Moore-Read pfaffian
wavefunction for the 5/2 fractional quantum Hall effect
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