1,531 research outputs found
Magnus Force in High Temperature Superconductivity and Berry Phase
In the topological framework of high temperature superconductivity we have
discussed the Magnus force acting on its vortices
Effect of Edge Roughness on Electronic Transport in Graphene Nanoribbon Channel Metal Oxide Semiconductor Field-Effect Transistors
Results of quantum mechanical simulations of the influence of edge disorder
on transport in graphene nanoribbon metal oxide semiconductor field-effect
transistors (MOSFETs) are reported. The addition of edge disorder significantly
reduces ON-state currents and increases OFF-state currents, and introduces wide
variability across devices. These effects decrease as ribbon widths increase
and as edges become smoother. However the bandgap decreases with increasing
width, thereby increasing the band-to-band tunneling mediated subthreshold
leakage current even with perfect nanoribbons. These results suggest that
without atomically precise edge control during fabrication, MOSFET performance
gains through use of graphene will be difficult to achieve.Comment: 8 pages, 5 figure
Calibration of a solid state nuclear track detector (SSNTD) with high detection threshold to search for rare events in cosmic rays
We have investigated a commercially available polymer for its suitability as
a solid state nuclear track detector (SSNTD). We identified that polymer to be
polyethylene terephthalate (PET) and found that it has a higher detection
threshold compared to many other widely used SSNTDs which makes this detector
particularly suitable for rare event search in cosmic rays as it eliminates the
dominant low Z background. Systematic studies were carried out to determine its
charge response which is essential before any new material can be used as an
SSNTD. In this paper we describe the charge response of PET to 129Xe, 78Kr and
49Ti ions from the REX-ISOLDE facility at CERN, present the calibration curve
for PET and characterize it as a nuclear track detector
To study the oxidative stress induced by lindane in epileptic rats brains and their modulation by neurosteroids
Background: Lindane is pesticide has been shown to affect the nervous system adversely. Previous work has shown that lindane is proconvulsant and neurosteroids (NS) has been shown to be neuroprotective against lindane-induced convulsions. As the mechanisms of lindane in epileptogenesis is not completely understood. The present study was designed to investigate the oxidative stress parameters of lindane toxicity in epileptogenesis and their modulation by NS like allopregnanolone (AP), and 4ʹ-chlorodiazepam (4ʹ-CD) in pentylenetetrazole (PTZ) kindling methods.Methods: Kindling was induced by injecting PTZ (30 mg/kg; s.c.) on alternate days i.e., 3 times in a week. Lindane was also administered (15 mg/kg p.o) on alternate days for 6 weeks. AP (2.5 mg/kg, intaperitoneal [i.p.]) and 4ʹ-CD (0.5 mg/kg, i.p.) single dose was given in kindled rats before lindane.Results: Following per oral administration of lindane for 6 weeks produced significant oxidative stress in epileptic brain. There was an increase in brain malondialdehyde (MDA) level and decrease in reduced glutathione (GSH) levels. AP (2.5 mg/kg, i.p.) and 4ʹ-CD (0.5 mg/kg, i.p.) single dose administration were not able to reverse the effect of chronic exposure of lindane.Conclusion: The result of the present study provides evidence that oxidative stress produced in the brain after chronic exposure of lindane may be the mechanism of epileptogenesis. Though NS have been shown to be neuroprotective, but they failed to reverse chronic oxidative stress produced by lindane. Further studies are required to demonstrate interaction of NS with lindane in oxidative stress
High Superconductivity, Skyrmions and the Berry Phase
It is here pointed out that the antiferromagnetic spin fluctuation may be
associated with a gauge field which gives rise to the antiferromagnetic ground
state chirality. This is associated with the chiral anomaly and Berry phase
when we consider the two dimensional spin system on the surface of a 3D sphere
with a monopole at the centre. This realizes the RVB state where spinons and
holons can be understood as chargeless spins and spinless holes attached with
magnetic flux. The attachment of the magnetic flux of the charge carrier
suggest, that this may be viewed as a skyrmion. The interaction of a massless
fermion representing a neutral spin with a gauge field along with the
interaction of a spinless hole with the gauge field enhances the
antiferromagnetic correlation along with the pseudogap at the underdoped
region. As the doping increases the antiferromagnetic long range order
disappears for the critical doping parameter . In this framework,
the superconducting pairing may be viewed as caused by skyrmion-skyrmion bound
states.Comment: 10 pages, accepted in Phys. Rev.
Characterization of fragment emission in ^{20}Ne (7 - 10 MeV/nucleon) + ^{12}C reactions
The inclusive energy distributions of the complex fragments (3 Z
7) emitted from the bombardment of ^{12}C by ^{20}Ne beams with incident
energies between 145 and 200 MeV have been measured in the angular range
10 50^{o}. Damped fragment yields in all the cases
have been found to be the characteristic of emission from fully energy
equilibrated composites. The binary fragment yields are compared with the
standard statistical model predictions. Enhanced yields of entrance channel
fragments (5 Z 7) indicate the survival of orbiting-like process
in ^{20}Ne + ^{12}C system at these energies.Comment: 18 pages, 13 figure
Survival of orbiting in Ne (7 - 10 MeV/nucleon) + C reactions
The inclusive energy distributions of fragments with Z 3 emitted from
the bombardment of C by Ne beams with incident energies between
145 and 200 MeV have been measured in the angular range
10 - 50. Damped fragment yields in all cases have been found to
be characteristic of emission from fully energy equilibrated composites; for B,
C fragments, average Q-values, , were independent of the centre of mass
emission angle (), and the angular distributions followed
1/sin like variation, signifying long life times of the
emitting di-nuclear systems. Total yields of these fragments have been found to
be much larger compared to the standard statistical model predictions of the
same. This may be indicative of the survival of orbiting like process in
C + Ne system at these energies.Comment: 7 pages, 5 figures, accepted for publication in Phys. Rev. C (Rapid
Communication
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