70 research outputs found
Immediate and short-term clinical outcome of primary PCI at startup tertiary care cardiac hospital in Uttarakhand
Superconducting properties and Hall Effect of epitaxial NbN thin films
We have measured the magnetotransport properties and Hall effect of a series
of epitaxial NbN films grown on (100) oriented single crystalline MgO substrate
under different conditions using reactive magnetron sputtering. Hall effect
measurements reveal that the carrier density in NbN thin films is sensitive to
the growth condition. The carrier density increases by a factor of 3 between
the film with highest normal state resistivity (rho_n~3.83micro-Ohm-m) and
lowest transition temperature (Tc~9.99K) and the film with lowest normal state
resistivity (rho_n~0.94micro-Ohm-m) and highest transition temperature
(Tc~16.11K) while the mobility of carriers does not change significantly except
for the most resistive films. Our results show that the Tc of NbN is governed
primarily by the carrier density rather than disorder scattering. By varying
the carrier concentration during growth we can vary the effective disorder
(kF_l) from the moderately clean limit to the dirty limit which makes this
system ideal to study the interplay of carrier density and disorder on the
superconducting properties of an s-wave superconductor.Comment: ps files with figures (accepted for publication in Phys. Rev. B
Penetration depth and tunneling studies in very thin epitaxial NbN films
We investigate evolution of the magnetic penetration depth and
superconducting energy gap in epitaxial NbN films using a low frequency mutual
inductance technique and tunneling spectroscopy using a low temperature
scanning tunneling microscope (STM). The superconducting transition temperature
(Tc) for films grown under optimal growth conditions decreases monotonically
from 15.87K to 9.16K as the film thickness is decreased from 50nm to 3nm. With
decrease in film thickness delta(0) monotonically decreases, whereas lambda(0)
monotonically increases. We observe that Tc, lambda(o) and delta(0) are well
described by Bardeen-Cooper-Schrieffer (BCS) theory in all films other than the
two thinnest ones where we see evidence of the Kosterlitz-Thouless-Berezinski
(KTB) transition close to Tc.Comment: Modified version with extensive analysis of the KTB transition. One
new author adde
Phase diagram of a strongly disordered s-wave superconductor, NbN, close to the metal-insulator transition
We present a phase diagram as a function of disorder in three-dimensional NbN
thin films, as the system enters the critical disorder for the destruction of
the superconducting state. The superconducting state is investigated using a
combination of magnetotransport and tunneling spectroscopy measurements. Our
studies reveal 3 different disorder regimes. At low disorder the (k_{F}l~10-4),
the system follows the mean field Bardeen-Cooper-Schrieffer behavior where the
superconducting energy gap vanishes at the temperature where electrical
resistance appears. For stronger disorder (k_{F}l<4) a "pseudogap" state
emerges where a gap in the electronic spectrum persists up to temperatures much
higher than Tc, suggesting that Cooper pairs continue to exist in the system
even after the zero resistance state is destroyed. Finally, very strongly
disordered samples (k_{F}l<1) exhibit a pronounced magnetoresistance peak at
low temperatures, suggesting that localized Cooper pairs continue to survive in
the system even after the global superconducting ground state is completely
destroyed.Comment: pdf file with figures (Modified Version
Tunneling studies in a homogeneously disordered s-wave superconductor: NbN
We report the evolution of superconducting properties as a function of
disorder in homogeneously disordered epitaxial NbN thin films grown on (100)
MgO substrates, studied through a combination of electrical transport, Hall
Effect and tunneling measurements. The thickness of all our films are >50nm
much larger than the coherence length ~5nm. The effective disorder in different
films encompasses a large range, with the Ioffe-Regel parameter varying in the
range kFl~1.38-8.77. Tunneling measurements on films with different disorder
reveals that for films with large disorder the bulk superconducting transition
temperature (Tc) is not associated with a vanishing of the superconducting
energy gap, but rather a large broadening of the superconducting density of
states. Our results provide strong evidence of the loss of superconductivity
via phase-fluctuations in a disordered s-wave superconductor.Comment: pdf file including figure
Phase diagram and upper critical field of homogenously disordered epitaxial 3-dimensional NbN films
We report the evolution of superconducting properties with disorder, in
3-dimensional homogeneously disordered epitaxial NbN thin films. The effective
disorder in NbN is controlled from moderately clean limit down to Anderson
metal-insulator transition by changing the deposition conditions. We propose a
phase diagram for NbN in temperature-disorder plane. With increasing disorder
we observe that as kFl-->1 the superconducting transition temperature (Tc) and
minimum conductivity (sigma_0) go to zero. The phase diagram shows that in
homogeneously disordered 3-D NbN films, the metal-insulator transition and the
superconductor-insulator transition occur at a single quantum critical point at
kFl~1.Comment: To appear in Journal of Superconductivity and Novel Magnetism
(ICSM2010 proceedings
Samarium-153 ethylenediamine tetramethylene phosphonate therapy for bone pain palliation in skeletal metastases
BACKGROUND: Systemic therapy with radionuclides may be used for the
treatment of patients with painful skeletal metastases owing to its
efficacy, low cost and low toxicity. Imported radionuclides for pain
palliation, like Strontium-89 are expensive; particularly for
developing countries. In the Indian scenario, Samarium-153 (Sm-153) is
produced in our own reactors and as a result, it is readily available
and economical. AIM: We undertook this study to determine the
efficacy and toxicity of single-dose Sm-153 ethylenediamine
tetramethylene phosphonate as a palliative treatment for painful
skeletal metastases. MATERIALS AND METHODS: Eightysix patients with
painful skeletal metastases from various primaries, were treated with
Sm-153 EDTMP at a dose of 37 MBq/kg. The effects were evaluated
according to change in visual analogue pain score, analgesic
consumption, Karnofsky performance score, mobility score and blood
count tests, conducted regularly for 16 weeks. STATISTICS: Repeated
measures analysis. RESULTS: The overall response rates were 73%, while
complete response was seen in 12.4%. Reduction in analgesic consumption
with improvement in Karnofsky performance score and mobility score, was
seen in all responders. Response rates were 80.3 and 80.5% in breast
and prostate cancer, respectively. One case, each of Wilms tumor,
ovarian cancer, germ cell tumor testis, multiple myeloma, primitive
neuroectodermal tumor and oesophageal cancer, did not respond to
therapy. No serious side-effects were noted, except for fall in white
blood cell, platelet and haemoglobin counts, which gradually returned
to normal levels by six-eight weeks. CONCLUSION: Sm-153 EDTMP
provided effective palliation in 73% patients with painful bone
metastases: the major toxicity was temporary myelosuppression
Temperature dependence of resistivity and Hall-coefficient in a strongly disordered metal: NbN
We report the temperature dependence of resistivity (rho) and Hall
coefficient (R_H) in the normal state of homogeneously disordered epitaxial NbN
thin films with kFl~3.27-10.12. The superconducting transition temperature (Tc)
of these films varies from 8.13K to 16.8K. While our least disordered film
displays usual metallic behavior, for all the films with kFl<8.13, both and are
negative up to 300K. We observe that R_H(T) varies linearly with rho(T) for all
the films. Measurements performed on a 2nm thick Be film shows similar behavior
>. This behavior is inconsistent with existing theories of localization and e-e
interactions in a disordered metal.Comment: pdf file with figure
A bibliography of parasites and diseases of marine and freshwater fishes of India
With the increasing demand for fish as human food, aquaculture both in freshwater
and salt water is rapidly developing over the world. In the developing countries,
fishes are being raised as food. In many countries fish farming is a very important
economic activity. The most recent branch, mariculture, has shown advances in
raising fishes in brackish, estuarine and bay waters, in which marine, anadromous and
catadromous fishes have successfully been grown and maintained
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