Diurnal-scale signatures of monsoon rainfall over the Indian region from TRMM satellite observations

One of the most important modes of summer season precipitation variability over the Indian region, the diurnal cycle, is studied using the Tropical Rainfall Measuring Mission 3-hourly, 0.25 degrees x 0.25 degrees 3B42 rainfall product for nine years (1999-2007). Most previous studies have provided an analysis of a single year or a few years of satellite-or station-based rainfall data. Our study aims to systematically analyze the statistical characteristics of the diurnal-scale signature of rainfall over the Indian and surrounding regions. Using harmonic analysis, we extract the signal corresponding to diurnal and subdiurnal variability. Subsequently, the 3-hourly time period or the octet of rainfall peak for this filtered signal, referred to as the ``peak octet,'' is estimated, with care taken to eliminate spurious peaks arising out of Gibbs oscillations. Our analysis suggests that over the Bay of Bengal, there are three distinct modes of the peak octet of diurnal rainfall corresponding to 1130, 1430, and 1730 Indian standard time (IST), from the north central to south bay. This finding could be seen to be consistent with southward propagation of the diurnal rainfall pattern reported by earlier studies. Over the Arabian Sea, there is a spatially coherent pattern in the mode of the peak octet (1430 IST), in a region where it rains for more than 30% of the time. In the equatorial Indian Ocean, while most of the western part shows a late night/early morning peak, the eastern part does not show a spatially coherent pattern in the mode of the peak octet owing to the occurrence of a ual maxima (early morng and early/late afternoon). The imalayan foothills were found to have a mode of peak octet corresponding to 0230 IST, whereas over the Burmese mountains and the Western Ghats (west coast of India) the rainfall peaks during late afternoon/early evening (1430-1730 IST). This implies that the phase of the diurnal cycle over inland orography (e. g., Himalayas) is significantly different from coastal orography (e. g., Western Ghats). We also find that over the Gangetic plains, the peak octet is around 1430 IST, a few hours earlier compared to the typical early evening maxima over land.

Functional and regulatory characteristics of eukaryotic type II DNA topoisomerase

DNA topoisomerases are ubiquitous nuclear enzymes that govern the topological interconversions of DNA by transiently breaking/rejoining the phosphodiester backbone of one (type I) or both (type II) strands of the double helix. Consistent with these functions, topoisomerases play key roles in many aspects of DNA metabolism. Type II DNA topoisomerase (topo II) is vital for various nuclear processes, including DNA replication, chromosome segregation, and maintenance of chromosome structure. Topo II expression is regulated at multiple stages, including transcriptional, posttranscriptional, and posttranslational levels, by a multitude of signaling factors. Topo II is also the cellular target for a variety of clinically relevant anti-tumor drugs. Despite significant progress in our understanding of the role of topo II in diverse nuclear processes, several important aspects of topo II function, expression, and regulation are poorly understood. We have focused this review specifically on eukaryotic DNA topoisomerase II, with an emphasis on functional and regulatory characteristics.

Binding and regulatory properties of phosphofructokinase from swine kidney

The influence of fructose 2,6-bisphosphate on the activation of purified swine kidney phosphofructokinase as a function of the concentration of fructose 6P, ATP and citrate was investigated. The purified enzyme was nearly completely inhibited in the presence of 2 mM ATP. The addition of 20 nM fructose 2,6-P2 reversed the inhibition and restored more than 80% of the activity. In the absence of fructose 2,6-P2 the reaction showed a sigmoidal dependence on fructose-6-phosphate. The addition of 10 nM fructose 2,6-bisphosphate decreased the K0.5 for fructose 6-phosphate from 3 mM to 0.4 mM in the presence of 1.5 mM ATP. These results clearly show that fructose 2,6-bisphosphate increases the affinity of the enzyme for fructose 6-phosphate and decreases the inhibitory effect of ATP. The extent of inhibition by citrate was also significantly decreased in the presence of fructose 2,6-phosphate. The influence of various effectors of phosphofructokinase on the binding of ATP and fructose 6-P to the enzyme was examined in gel filtration studies. It was found that kidney phosphofructokinase binds 5.6 moles of fructose 6-P per mole of enzyme, which corresponds to about one site per subunit of tetrameric enzyme. The KD for fructose 6-P was 13 microM and in the presence of 0.5 mM ATP it increased to 27 microM. The addition of 0.3 mM citrate also increased the KD for fructose 6-P to about 40 microM. AMP, 10 microM, decreased the KD to 5 microM and the addition of fructose 2,6-phosphate decreased the KD for fructose 6-P to 0.9 microM. The addition of these compounds did not effect the maximal amount of fructose 6-P bound to the enzyme, which indicated that the binding site for these compounds might be near, but was not identical to the fructose 6-P binding site. The enzyme bound a maximum of about 12.5 moles of ATP per mole, which corresponds to 3 moles per subunit. The KD of the site with the highest affinity for ATP was 4 microM, and it increased to 15 microM in the presence of fructose 2,6-bisphosphate. The addition of 50 microM fructose 1,6-bisphosphate increased the KD for ATP to 5.9 microM. AMP increased the KD to 5.9 microM whereas 0.3 mM citrate decreased the KD for ATP to about 2 microM.(ABSTRACT TRUNCATED AT 400 WORDS).

Three-User Cognitive Channels with Cumulative Message Sharing: An Achievable Rate Region

In this paper, an achievable rate region for the three-user discrete memoryless interference channel with asymmetric transmitter cooperation is derived. The three-user channel facilitates different ways of message sharing between the transmitters. We introduce a manner of noncausal (genie aided) unidirectional message-sharing, which we term cumulative message sharing. We consider receivers with predetermined decoding capabilities, and define a cognitive interference channel. We then derive an achievable rate region for this channel by employing a coding scheme which is a combination of superposition and Gel'fand-Pinsker coding techniques.

Analysis of stability of earthen dams in kachchh region, Gujarat, India

The Kachchh region of Gujarat, India bore the brunt of a disastrous earthquake of magnitude M-w=7.6 that occurred on January 26, 2001. The major cause of failure of various structures including earthen dams was noted to be the presence of liquefiable alluvium in the foundation soil. Results of back-analysis of failures of Chang, Tappar, Kaswati and Rudramata earth dams using pseudo-static limit equilibrium approach presented in this paper confirm that the presence of liquefiable layer contributed to lesser factors of safety leading to a base type of failure that was also observed in the field. Following the earthquake, earth dams have been rehabilitated by the concerned authority and it is imperative that the reconstructed sections of earth dams be reanalyzed. It is also increasingly realized that risk assessment of dams in view of the large-scale investment made and probabilistic analysis is necessary. In this study, it is demonstrated that the probabilistic approach when used in conjunction with deterministic approach helps in providing a rational solution for quantification of safety of the dam and in the estimation of risk associated with the dam construction. (C) 2007 Elsevier B.V. All rights reserved.

Mapping of Average Shear Wave Velocity for Bangalore Region: A Case Study

Mapping the shear wave velocity profile is an important part in seismic hazard and microzonation studies. The shear wave velocity of soil in the city of Bangalore was mapped using the Multichannel Analysis of Surface Wave (MASW) technique. An empirical relationship was found between the Standard Penetration Test (SPT) corrected N value ((N1)60cs) and measured shear wave velocity (Vs). The survey points were selected in such a way that the results represent the entire Bangalore region, covering an area of 220 km2. Fifty-eight 1-D and 20 2-D MASW surveys were performed and their velocity profiles determined. The average shear wave velocity of Bangalore soils was evaluated for depths of 5 m, 10 m, 15 m, 20 m, 25 m and 30 m. The sub-soil classification was made for seismic local site effect evaluation based on average shear wave velocity of 30-m depth (Vs30) of sites using the National Earthquake Hazards Reduction Program (NEHRP) and International Building Code (IBC) classification. Mapping clearly indicates that the depth of soil obtained from MASW closely matches with the soil layers identified in SPT bore holes. Estimation of local site effects for an earthquake requires knowledge of the dynamic properties of soil, which is usually expressed in terms of shear wave velocity. Hence, to make use of abundant SPT data available on many geotechnical projects in Bangalore, an attempt was made to develop a relationship between Vs (m/s) and (N1)60cs. The measured shear wave velocity at 38 locations close to SPT boreholes was used to generate the correlation between the corrected N values and shear wave velocity. A power fit model correlation was developed with a regression coefficient (R2) of 0.84. This relationship between shear wave velocity and corrected SPT N values correlates well with the Japan Road Association equations.

Total cross-section at LHC from minijets and soft gluon resummation in the infrared region

A model for total cross-sections incorporating QCD jet cross-sections and soft gluon resummation is described and compared with present data on pp and pp cross-sections. Predictions for LHC are presented for different parameter sets. It is shown that they differ according to the small x-behaviour of available parton density functions.

Stereoselective Synthesis of C1-C18 Region of Palmerolide A from Tartaric Acid

A stereoselective synthesis of the C1-C18 region of marine natural product palmerolide A from chiral pool tartaric acid is presented. The key synthetic sequence includes the elaboration of a gamma-oxo-amide derived from tartaric acid and alkene formation involving Boord type fragmentation.

Topography of the combining region of a Thomsen-Friedenreich-antigen-specific lectin jacalin (Artocarpus integrifolia agglutinin). A thermodynamic and circular-dichroism spectroscopic study

Thermodynamic analysis of carbohydrate binding by Artocarpus integrifolia (jackfruit) agglutinin (jacalin) shows that, among monosaccharides, Me alpha GalNAc (methyl-alpha-N-acetylgalactosamine) is the strongest binding ligand. Despite its strong affinity for Me alpha GalNAc and Me alpha Gal, the lectin binds very poorly when Gal and GalNAc are in alpha-linkage with other sugars such as in A- and B-blood-group trisaccharides, Gal alpha 1-3Gal and Gal alpha 1-4Gal. These binding properties are explained by considering the thermodynamic parameters in conjunction with the minimum energy conformations of these sugars. It binds to Gal beta 1-3GalNAc alpha Me with 2800-fold stronger affinity over Gal beta 1-3GalNAc beta Me. It does not bind to asialo-GM1 (monosialoganglioside) oligosaccharide. Moreover, it binds to Gal beta 1-3GalNAc alpha Ser, the authentic T (Thomsen-Friedenreich)-antigen, with about 2.5-fold greater affinity as compared with Gal beta 1-3GalNAc. Asialoglycophorin A was found to be about 169,333 times stronger an inhibitor than Gal beta 1-3GalNAc. The present study thus reveals the exquisite specificity of A. integrifolia lectin for the T-antigen. Appreciable binding of disaccharides Glc beta 1-3GalNAc and GlcNAc beta 1-3Gal and the very poor binding of beta-linked disaccharides, which instead of Gal and GalNAc contain other sugars at the reducing end, underscore the important contribution made by Gal and GalNAc at the reducing end for recognition by the lectin. The ligand-structure-dependent alterations of the c.d. spectrum in the tertiary structural region of the protein allows the placement of various sugar units in the combining region of the lectin. These studies suggest that the primary subsite (subsite A) can accommodate only Gal or GalNAc or alpha-linked Gal or GalNAc, whereas the secondary subsite (subsite B) can associate either with GalNAc beta Me or Gal beta Me. Considering these factors a likely arrangement for various disaccharides in the binding site of the lectin is proposed. Its exquisite specificity for the authentic T-antigen, Gal beta 1-3GalNAc alpha Ser, together with its virtual non-binding to A- and B-blood-group antigens, Gal beta 1-3GalNAc beta Me and asialo-GM1 should make A. integrifolia lectin a valuable probe for monitoring the expression of T-antigen on cell surfaces.

Characterization of the human SLC22A18 gene promoter and its regulation by the transcription factor Sp1

SLC22A18, a poly-specific organic cation transporter, is paternally imprinted in humans and mice. It shows loss-of-heterozygosity in childhood and adult tumors, and gain-of-imprinting in hepatocarcinomas and breast cancers. Despite the importance of this gene, its transcriptional regulation has not been studied, and the promoter has not yet been characterized. We therefore set out to identify the potential cis-regulatory elements including the promoter of this gene. The luciferase reporter assay in human cells indicated that a region from -120 by to +78 by is required for the core promoter activity. No consensus TATA or CHAT boxes were found in this region, but two Sp1 binding sites were conserved in human, chimpanzee, mouse and rat. Mutational analysis of the two Sp1 sites suggested their requirement for the promoter activity. Chromatin-immunoprecipitation showed binding of Sp1 to the promoter region in vivo. Overexpression of Sp1 in Drosophila Sp1-null SL2 cells suggested that Sp1 is the transactivator of the promoter. The human core promoter was functional in mouse 3T3 and monkey COS7 cells. We found a CpG island which spanned the core promoter and exon 1. COBRA technique did not reveal promoter methylation in 10 normal oral tissues, 14 oral tumors, and two human cell lines HuH7 and A549. This study provides the first insight into the mechanism that controls expression of this imprinted tumor suppressor gene. A COBRA-based assay has been developed to look for promoter methylation in different cancers. The present data will help to understand the regulation of this gene and its role in tumorigenesis. (C) 2008 Elsevier B.V. All rights reserved.

Characterization of the human SLC22A18 gene promoter and its regulation by the transcription factor Sp1

SLC22A18, a poly-specific organic cation transporter, is paternally imprinted in humans and mice. It shows loss-of-heterozygosity in childhood and adult tumors, and gain-of-imprinting in hepatocarcinomas and breast cancers. Despite the importance of this gene, its transcriptional regulation has not been studied, and the promoter has not yet been characterized. We therefore set out to identify the potential cis-regulatory elements including the promoter of this gene. The luciferase reporter assay in human cells indicated that a region from -120 by to +78 by is required for the core promoter activity. No consensus TATA or CHAT boxes were found in this region, but two Sp1 binding sites were conserved in human, chimpanzee, mouse and rat. Mutational analysis of the two Sp1 sites suggested their requirement for the promoter activity. Chromatin-immunoprecipitation showed binding of Sp1 to the promoter region in vivo. Overexpression of Sp1 in Drosophila Sp1-null SL2 cells suggested that Sp1 is the transactivator of the promoter. The human core promoter was functional in mouse 3T3 and monkey COS7 cells. We found a CpG island which spanned the core promoter and exon 1. COBRA technique did not reveal promoter methylation in 10 normal oral tissues, 14 oral tumors, and two human cell lines HuH7 and A549. This study provides the first insight into the mechanism that controls expression of this imprinted tumor suppressor gene. A COBRA-based assay has been developed to look for promoter methylation in different cancers. The present data will help to understand the regulation of this gene and its role in tumorigenesis. (C) 2008 Elsevier B.V. All rights reserved.

Reactive characteristics of narrow germanium p-n junctions in the breakdown region

An inductive behaviour observed in germanium p-n junctions in the breakdown region is reported.

Reverse bias capacitance measurements on copper-doped germanium p-n junctions in the breakdown region

Results of measurements at a high frequency on reverse bias capacitance of copper-doped germanium junctions are reported. Phenomenal increase in capacitance is found in the breakdown region, particularly at low temperatures.

Compressible axially symmetric laminar boundary layer flow in the stagnation region of a blunt body in the presence of magnetic field

In this paper, the steady laminar viscous hypersonic flow of an electrically conducting fluid in the region of the stagnation point of an insulating blunt body in the presence of a radial magnetic field is studied by similarity solution approach, taking into account the variation of the product of density and viscosity across the boundary layer. The two coupled non-linear ordinary differential equations are solved simultaneously using Runge-Kutta-Gill method. It has been found that the effect of the variation of the product of density and viscosity on skin friction coefficient and Nusselt number is appreciable. The skin friction coefficient increases but Nusselt number decreases as the magnetic field or the total enthalpy at the wall increases