4,443 research outputs found
On long-wavelength magnetic anomalies over Indian region
A data set composed of vector magnetic measurements obtained by MAGSAT and very accurate altitude determinations made using Sun sensors and star cameras was used to obtain data for very quiet days over the Indian region at 10 S to 40 N and 60 E to 110 E in an effort to determine the validity of quantitative estimates made from aeromagnetic data obtained by removing the core field. To further account for the external effects, the ring current contributions estimated using both X and Z variations were subtracted from the observed values. Before this, the core contribution was eliminated through a spherical harmonic expansion with terms up to N=13. Analysis of the residual measurements using Fast Fourier techniques indicates that the anomalies contain substantial power for wavelengths of about 1500 kms. Because the ring current effect has a spatial structure of this dimension over India, efforts are being made to exactly eliminate these two interfering effects from the data
Extrahepatic undifferentiated embryonal sarcoma, cytology as an accurate method for early diagnosis: an extremely rare case report in an Indian child
Undifferentiated embryonal sarcoma has been described in the liver, a rare malignant mesenchymal neoplasm, that occurs primarily in children and teenagers. Approximately 260 cases have been reported arising in the liver since 1978 when this disease was first described. Its pathogenesis is still obscure. Authors presented a case of extrahepatic undifferentiated embryonal sarcoma in a 9-year-old female presenting with upper abdominal dull pain. Ultrasound and CT Scan showed normal liver architecture, with liver pushed upwards due to compression by tumor arising in the retroperitoneum. To the best of our knowledge, this is first case of extrahepatic undifferentiated embryonal sarcoma diagnosed on cytomorphology and confirmed by histopathology and immunohistochemistry markers
Birefringence analysis of multilayer leaky cladding optical fibre
We analyse a multilayer leaky cladding (MLC) fibre using the finite element
method and study the effect of the MLC on the bending loss and birefringence of
two types of structures: (i) a circular core large-mode-area structure and (ii)
an elliptical-small-core structure. In a large-mode-area structure, we verify
that the multilayer leaky cladding strongly discriminates against higher order
modes to achieve single-mode operation, the fibre shows negligible
birefringence, and the bending loss of the fibre is low for bending radii
larger than 10 cm. In the elliptical-small-core structure we show that the MLC
reduces the birefringence of the fibre. This prevents the structure from
becoming birefringent in case of any departures from circular geometry. The
study should be useful in the designs of MLC fibres for various applications
including high power amplifiers, gain flattening of fibre amplifiers and
dispersion compensation.Comment: 18 page
TSUNAMIGENIC SOURCES IN THE INDIAN OCEAN
Based on an assessment of the repeat periods of great earthquakes from past seismicity, convergence rates and paleoseismological results, possible future source zones of tsunami generating earthquakes in the Indian Ocean (possible seismic gap areas) are identified along subduction zones and zones of compression. Central Sumatra, Java, Makran coast, Indus Delta, Kutch-Saurashtra, Bangladesh and southern Myanmar are identified as possible source zones of earthquakes in near future which might cause tsunamis in the Indian Ocean, and in particular, that could affect India. The Sunda Arc (covering Sumatra and Java) subduction zone, situated on the eastern side of the Indian Ocean, is one of the most active plate margins in the world that generates frequent great earthquakes, volcanic eruptions and tsunamis. The Andaman- Nicobar group of islands is also a seismically active zone that generates frequent earthquakes. However, northern Sumatra and Andaman-Nicobar regions are assessed to be probably free from great earthquakes (M!8.0) for a few decades due to occurrence of 2004 Mw 9.3 and 2005 Mw 8.7 earthquakes. The Krakatau volcanic eruptions have caused large tsunamis in the past. This volcano and a few others situated on the ocean bed can cause large tsunamis in the future. List of past tsunamis generated due to earthquakes/volcanic eruptions that affected the Indian region and vicinity in the Indian Ocean are also presented
Substituted Thiobiurets as Corrosion Inhibitors for Mild Steel in L.ON Sulphuric Acid
Corrosion inhibition studies of mild steel in 1.ON sulphuric acid have been performed at 25°C using substituted thiobiurets as inhibitors. All the inhibit-
ors were found to inhibit the process by getting adsorbed on the metal surface. A comparative account of inhibition
efficiencies of different compounds has been given consi-dering their size and probable sites through which adsor-ption can take place. Among the studied thiobiurets
methoxyphenyl derivative behaved as the best corrosion inhibitor followed by mefhylphenyl-, phenyl- and chlorophenyl-derivatives
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