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Search for supersymmetry in final states with photons and missing transverse momentum in proton-proton collisions at 13 TeV
No full textResults are reported of a search for supersymmetry in final states with photons and missing transverse momentum in proton-proton collisions at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb(-1) collected at a center-of-mass energy of 13 TeV using the CMS detector. The results are interpreted in the context of models of gauge-mediated supersymmetry breaking. Production cross section limits are set on gluino and squark pair production in this framework. Gluino masses below 1.86 TeV and squark masses below 1.59 TeV are excluded at 95% confidence level
An unconstrained ellipse fitting technique and application to optic cup segmentation
No full textWe present a novel method for fitting an ellipse to scattered data based on least-squares minimization. The new technique has several advantages over the standard ellipse fitting techniques. For one, it is constraint-free and computationally inexpensive thus making it easy to implement. Also, despite the absence of constraints, execution of the model always results in an ellipse fit. Additionally, the model results in a singular solution for a given set of datapoints. The proposed model is compared with standard techniques and shown to have the ability to fit an accurate ellipse even when other methods either fail to be ellipse-specific or take up excessive computation time for execution. An application to the problem of segmentation of the optic cup in retinal fundus images, is also presented. Experimental validation and performance comparisons show that the proposed technique is competitive with the state-of-the-art methods. © 2018 IEEE
Studies on High Voltage Composite Insulators under very low Temperature
No full textWith the advancement in material engineering new insulation materials have been developed with enhanced insulating properties and these materials have certain advantages over glass and porcelain insulators in terms of field performance. Since last decade there is an increase in demand of installing polymer/composite insulator as a preferable choice. These have promising features for high voltage transmission and distribution applications. However, long-term environmental and electric stresses could cause surface degradation and in due course reduce the insulation strength of insulators. In the present work, an attempt is made to study the effect of multiple stresses (humidity, low temperature, UV and electric stress) on the composite insulators. The experimental chamber of 2.5 x 2.5 x 2.5 ft is suitably fabricated for the experiment. The leakage current is regularly monitored over the experimental duration of 1000 hours. The surface morphological studies using Fourier transform infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), Wettability Class (WC) measurements and performance of tensile strength of the samples are conducted on the samples before and after experimentation. © 2018 IEEE
On the origin of a remarkable increase in the strength and stability of an Al rich Al-Ni eutectic alloy by Zr addition
No full textThe effect of Zr addition to Al rich binary α-Al - Al 3 Ni eutectic cast alloy (Al-3.1 at. Ni) in enhancing the microstructural stability and strength at high temperature is demonstrated. On subsequent heat treatment after casting, nanometric coherent L1 2 ordered Al 3 Zr precipitates form inside the α-Al that strengthen the alloy. Additionally, remarkable stability of eutectic microstructure was observed even after 100 h of annealing at 400 °C. The synergetic effect of the strengthening of the α-Al matrix by coherent Al 3 Zr precipitates and the low coarsening rate of the Al 3 Ni rods results in a significant increase in high temperature hardness and yield strength of the alloy. The tensile yield strength of the annealed Al-3.1Ni-0.15Zr alloy (400 °C, 10 h) tested at 250 °C is found to be 185 ± 10 MPa, which is 1.5 times higher than the corresponding binary Al-3.1Ni alloy. The experimentally determined average rod size (radius) during annealing at 400 °C follows the classical matrix diffusion controlled LSW-based coarsening model for both binary Al-3.1Ni and ternary Al-3.1Ni-0.15Zr alloys. The calculated coarsening rate constant values based on modified LSW coarsening model are 10.3 and 4.1 nm 3 /s for Al-3.1Ni and Al-3.1Ni-0.15Zr alloys, respectively. Atom probe tomographic (APT) investigations of the heat-treated ternary alloy unambiguously reveal segregation of Zr solute at the αAl/Al 3 Ni interface in addition to the presence of the strengthening Al 3 Zr ordered precipitates in the α-Al matrix. The segregation hinders the interdiffusion of Al and Ni in the eutectic and, thereby, increasing the stability of the eutectic phase at high temperature
Selective photodissociation of highly photoactive Bis-2-benzylidenemalononitrile in solution
No full textPhotophysical study of highly photoactive bis(-2)-benzylidenemalononitrile (BBM) has been investigated in solution using UV-vis, fluorescence and NMR spectroscopic techniques. The seletive photodissociation can be attributed to the presence of highly polarized C=C bond, attached to dicyno groups (CN). Nevertheless, the observed photodissociation of BBM is highly solvent specific and temperature sensitive. The product A (2-(4-formylbenzylidene)malononitrile), formed by the selective photodissociation of BBM under UV irradiation has been isolated and identified by NMR studies. The photodissociation followed the pseudo 1st order kinetics with a rate constant (k) 10(-3).10(-4).s(-1). Moreover the mechanistic study of selective photodissociation of bis(-2)-benzylidenemalononitrile (BBM) has been investigated and found to follow the dipolar mechanism path during photochemical reaction
DNA Translocation through Hybrid Bilayer Nanopores
No full textPore functionalization has been explored by several groups as a strategy to control DNA translocation through solid-state nanopores. Here we present a hybrid nanopore system consisting of single-layer graphene and a DNA origami layer to achieve base-selective control of DNA translocation rate through aligned nanopores of the two layers. This is achieved by incorporating unpaired dangling bases called overhangs to the origami near the pore region. Molecular dynamics simulations were used to optimize the design of the origami nanopore and the overhangs. Specifically, we considered the influence of the number and spatial distribution of overhangs on translocation times. The simulations revealed that specific interactions between the overhangs and the translocating single-stranded DNA resulted in base-specific residence times
Structural biology of plant lectins and macromolecular crystallography in India
No full textEarnest attempts at initiating macromolecular crystallography, which is central to modern biology, started in India in the 1970s. The most important component of the efforts was on plant lectins. The lectin programme was continuously and almost exclusively supported by the Department of Science and Technology, Government of India. Lectins are quintessential carbohydrate-binding proteins and have acquired considerable importance in relation to biological recognition at cell surface. The plant lectin programme at Bengaluru spanned 40 years and was instrumental in making significant contributions to glycobiology. The work has also produced important results pertaining to protein folding, quaternary association and strategies for generating ligand specificities. The role of the lectin programme in mentoring scientists has been important and many of the senior macromolecular crystallographers in the country were initially trained under this programme. Studies on plant lectins led to those on mycobacterial and archeal lectins. The lectin work has also served as a springboard for the initiation of several other long-range programmes which, in addition to yielding important results, have also helped in training scientists, many of whom are again leaders of structural biology in India. Perhaps, majority of macromolecular crystallographers in India are those who have been trained at Bengaluru and their descendants. Particularly in recent years, there has been an influx of scientists trained in other centres, who have added vibrance to the macromolecular crystallography community. The community is now reasonably coherent, with constructive interactions among its members, and with several common programmes and shared facilities
Nuclear targeting terpyridine iron(II) complexes for cellular imaging and remarkable photocytotoxicity (vol 116, pg 77, 2012)
No full textLong term observations on stable isotope ratios in rainwater samples from twin stations over Southern India; identifying the role of amount effect, moisture source and rainout during the dual monsoons
No full textThe dominant factor that controls the rainwater isotope ratios in the tropics is believed to be the local or instantaneous rainfall amount. This notion was challenged in several recent observations indicating that the stable ratios in rainwater are controlled by other factors such as source water composition and intensity of convective activity. Since amount effect is the basis for paleoclimate reconstruction of rainfall it is important to develop comprehensive knowledge about it at different time scales. Here we investigated the relationship of rainwater O-18 with the local or instantaneous rainfall amount at different time scales at two Indian stations, Thiruvananthapuram (TRV) and Bangalore (BLR), for four years covering the dual monsoon systems Indian Summer Monsoon (ISM) and Northeast Monsoon (NEM)]. It was observed that the seasonal variations are more pronounced over BLR due to its continental location in the central Southern peninsular India, compared to TRV which is a coastal station. Isotopically enriched samples were found during seasonal high temperature and low relative humidity at the respective stations. The intra-event observations indicated that the amount effect' at the intra-event scale was significant due to post-condensation evaporation, which was supported by low d-excess values and its inverse correlation with rainfall amount. The correlation between event based O-18 and local rainfall amount for both the stations was weak (r=0.2 and 0.3) whereas the isotopic signature was sensitive to the convective activity during the monsoon period. Significant negative spatio-temporal correlations of O-18 over the moisture convergence regions were obtained with proxies of convective activity over parts of the Arabian Sea as well as over the regions of moisture pathways associated with synoptic scale disturbances from the Bay of Bengal. We observed that the correlation pattern varies with the seasonal changes of moisture source and transport pathways during the periods of ISM and NEM
Null model exhibiting synchronized dynamics in uncoupled oscillators
No full textThe phenomenon of phase synchronization of oscillatory systems, arising out of feedback coupling is ubiquitous across physics and biology. In noisy, complex systems, one generally observes transient epochs of synchronization followed by nonsynchronous dynamics. How does one guarantee that the observed transient epochs of synchronization are arising from an underlying feedback mechanism and not from some peculiar statistical properties of the system? This question is particularly important for complex biological systems, where the search for a nonexistent feedback mechanism may turn out to be an enormous waste of resources. In this article, we propose a null model for synchronization, motivated by expectations on the dynamical behavior of biological systems, to provide a quantitative measure of the confidence with which one can infer the existence of a feedback mechanism based on observation of transient synchronized behavior. We demonstrate the application of our null model to the phenomenon of gait synchronization in free-swimming nematodes, Caenorhabditis elegans