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Measurements of tt differential cross sections in proton-proton collisions at √s = 13 TeV using events containing two leptons
No full textMeasurements of differential top quark pair tt cross sections using events produced in proton-proton collisions at a centre-of-mass energy of 13 TeV containing two oppositely charged leptons are presented. The data were recorded by the CMS experiment at the CERN LHC in 2016 and correspond to an integrated luminosity of 35.9 fb−1. The differential cross sections are presented as functions of kinematic observables of the top quarks and their decay products, the tt system, and the total number of jets in the event. The differential cross sections are defined both with particle-level objects in a fiducial phase space close to that of the detector acceptance and with parton-level top quarks in the full phase space. All results are compared with standard model predictions from Monte Carlo simulations with next-to-leading-order (NLO) accuracy in quantum chromodynamics
(QCD) at matrix-element level interfaced to parton-shower simulations. Where possible, parton level results are compared to calculations with beyond-NLO precision in QCD. Significant disagreement is observed between data and all predictions for several observables. The measurements are used to constrain the top quark chromomagnetic dipole moment in an effective field theory framework at NLO in QCD and to extract tt and leptonic charge asymmetries
Transparent on-waveguide electrical interconnects in SiN-photonic platform
No full textWe demonstrate transparent in-contact electrical interconnects over SiN micro-ring resonators using metallic carbon nano-tubes (CNTs). Self-assembled stripes of metallic CNTs are directly in contact with the waveguide operating around 1550nm wavelength. The absorption by the CNTs around 1550nm is negligible for a coverage of about 2 of the micro-ring. The optical performance of the resonator is unaffected till a current density of 35μA�μm. Semi-conducting CNTs with a similar coverage also have negligible absorption around 1550nm. These metallic and semi-conducting CNTs hold promise for the implementation of transparent electronic circuits over SiN-photonic platform. © 2019 Elsevier B.V
Molecular cartography of leaf development - role of transcription factors
No full textOrgan elaboration in plants occurs almost exclusively by an increase in cell number and size. Leaves, the planar lateral appendages of plants, are no exception. Forward and reverse genetic approaches have identified several genes whose role in leaf morphogenesis has been inferred from their primary effect on cell number and size, thereby distinguishing them as either promoters or inhibitors of cell proliferation and expansion. While such classification is useful in studying size control, a similar link between genes and shape generation is poorly understood. Computational modelling can provide a conceptual framework to re-evaluate the known genetic information and assign specific morphogenetic roles to the transcription factor-encoding genes. Here we discuss recent advances in our understanding of the roles of transcription factors in the planar growth of leaf lamina in two orthogonal dimensions
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
Turbulent power spectrum in warm and cold neutral medium using the Galactic HI 21 cm emission
No full textSmall-scale fluctuations of different tracers of the interstellar medium can be used to study the nature of turbulence in astrophysical scales. Of these, the `continuum' emission traces the fluctuations integrated along the line of sight whereas, the spectral line tracers give the information along different velocity channels as well. Recently, Miville-Deschenes et al. have measured the intensity fluctuation power spectrum of the continuum dust emission, and found a power-law behaviour with a power-law index of -2.9 +/- 0.1 for a region of our Galaxy. Here, we study the same region using high-velocity resolution 21-cm emission from the diffuse neutral medium, and estimate the power spectrum at different spectral channels. The measured 21-cm power spectrum also follows a power law, however, we see a significant variation in the power-law index with velocity. The value of the power-law index estimated from the integrated map for different components are quite different which is indicative of the different nature of turbulence depending on temperature, density, and ionization fraction. We also measure the power spectra after smoothing the 21 cm emission to velocity resolution ranging from 1.03 to 13.39 km s(-1), but the power spectrum remains unchanged within the error bar. This indicates that the observed fluctuations are dominantly due to density fluctuations, and we can only constrain the power-law index of velocity structure function of 0.0 +/- 1.1 which is consistent with the predicted Kolmogorov turbulence (gamma = 2/3) and also with a shock-dominated medium (gamma = 1.0)
Quasi-Optimality of Adaptive Mixed FEMs for Non-selfadjoint Indefinite Second-Order Linear Elliptic Problems
No full textThe well-posedness and the a priori and a posteriori error analysis of the lowest-order Raviart-Thomas mixed finite element method (MFEM) has been established for non-selfadjoint indefinite second-order linear elliptic problems recently in an article by Carstensen, Dond, Nataraj and Pani (Numer. Math., 2016). The associated adaptive mesh-refinement strategy faces the difficulty of the flux error control in H(div, Omega) and so involves a data-approximation error parallel to f - Pi(0)f parallel to in the L-2 norm of the right-hand side f and its piecewise constant approximation Pi(0)f. The separate marking strategy has recently been suggested with a split of a Dorfler marking for the remaining error estimator and an optimal data approximation strategy for the appropriate treatment of parallel to f -Pi(0)f parallel to(L)2((Omega)). The resulting strategy presented in this paper utilizes the abstract algorithm and convergence analysis of Carstensen and Rabus (SINUM, 2017) and generalizes it to general second-order elliptic linear PDEs. The argument for the treatment of the piecewise constant displacement approximation u(RT) is its supercloseness to the piecewise constant approximation Pi(0u) of the exact displacement u. The overall convergence analysis then indeed follows the axioms of adaptivity for separate marking. Some results on mixed and nonconforming finite element approximations on the multiply connected polygonal 2D Lipschitz domain are of general interest
Studying the rigidity of red blood cells induced by Plasmodium falciparum infection
No full textWe study the effect of different chemical moieties on the rigidity of red blood cells (RBCs) induced by Plasmodium falciparum infection, and the bystander effect previously found. The infected cells are obtained from a culture of parasite-infected RBCs grown in the laboratory. The rigidity of RBCs is measured by looking at the Brownian fluctuations of individual cells in an optical-tweezers trap. The results point towards increased intracellular cyclic adenosine monophosphate (cAMP) levels as being responsible for the increase in rigidity
On the convolution of Mittag-Leffler distributions and its applications to fractional point processes
No full textWe obtain the distribution of the sum of independent Mittag-Leffler (ML) random variables which are not necessarily identically distributed. Firstly we discuss the corresponding known result for independent and identically distributed ML random variables which follows as a special case of our result. Some applications of the obtained result to fractional point processes are also discussed
Topological insulator n-p-n junctions in a magnetic field
No full textElectrical transport in three dimensional topological insulators (TIs) occurs through spin-momentum locked topological surface states that enclose an insulating bulk. In the presence of a magnetic field, surface states get quantized into Landau levels giving rise to chiral edge states that are naturally spin-polarized due to spin momentum locking. It has been proposed that p-n junctions of TIs exposed to external magnetic fields can manifest unique spin dependent effects, apart from forming basic building blocks for highly functional spintronic devices. Here, for the first time we study electrostatically defined n-p-n junctions of dual-gated devices of the three dimensional topological insulator BiSbTe1.25Se1.75 in the presence of a strong magnetic field, revealing striking signatures of suppressed or enhanced electrical transport depending upon the chirality of quantum Hall edge states created at the n-p and p-n junction interfaces. Theoretical modeling combining the electrostatics of the dual gated TI n-p-n junction with the Landauer Buttiker formalism for transport through a network of chiral edge states explains our experimental data. Our work not only opens up a route towards exotic spintronic devices but also provides a test bed for investigating the unique signatures of quantum Hall effects in topological insulators
Structural and functional insights into phosphomannose isomerase: the role of zinc and catalytic residues
No full textPhosphomannose isomerase (PMI) is a housekeeping enzyme that is found in organisms ranging from bacteria to fungi to mammals and is important for cell-wall synthesis, viability and signalling. PMI is a zinc-dependent enzyme that catalyses the reversible isomerization between mannose 6-phosphate (M6P) and fructose 6-phosphate (F6P), presumably via the formation of a cis-enediol intermediate. The reaction is hypothesized to involve ring opening of M6P, the transfer of a proton from the C2 atom to the C1 atom and between the O1 and O2 atoms of the substrate, followed by ring closure resulting in the product F6P. Several attempts have been made to decipher the role of zinc ions and various residues in the catalytic function of PMI. However, there is no consensus on the catalytic base and the mechanism of the reaction catalyzed by the enzyme. In the present study, based on the structure of PMI from Salmonella typhimurium, site-directed mutagenesis targeting residues close to the bound metal ion and activity studies on the mutants, zinc ions were shown to be crucial for substrate binding. These studies also suggest Lys86 as the most probable catalytic base abstracting the proton in the isomerization reaction. Plausible roles for the highly conserved residues Lys132 and Arg274 could also be discerned based on comparison of the crystal structures of wild-type and mutant PMIs. PMIs from prokaryotes possess a low sequence identity to the human enzyme, ranging between 30% and 40%. Since PMI is important for the virulence of many pathogenic organisms, the identification of catalytically important residues will facilitate its use as a potential antimicrobial drug target