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Cortical tethering of mitochondria by the anchor protein Mcp5 enables uniparental inheritance
No full textDuring sexual reproduction in eukaryotes, processes such as active degradation and dilution of paternal mitochondria ensure maternal mitochondrial inheritance. In the isogamous organism fission yeast, we employed high-resolution fluorescence microscopy to visualize mitochondrial inheritance during meiosis by differentially labeling mitochondria of the two parental cells. Remarkably, mitochondria, and thereby mitochondrial DNA from the parental cells, did not mix upon zygote formation but remained segregated at the poles by attaching to clusters of the anchor protein Mcp5 via its coiled-coil domain. We observed that this tethering of parental mitochondria to the poles results in uniparental inheritance of mitochondria, wherein two of the four spores formed subsequently contained mitochondria from one parent and the other spores contained mitochondria from the other parent. Further, the presence of dynein on an Mcp5 cluster precluded the attachment of mitochondria to the same cluster. Taken together, we reveal a distinct mechanism that achieves uniparental inheritance by segregation of parental mitochondria
Asymptotically flat vacuum solution in modified theory of Einstein's gravity
No full textA number of recent observations have suggested that the Einstein's theory of general relativity may not be the ultimate theory of gravity. The f(R) gravity model with R being the scalar curvature turns out to be one of the best bet to surpass the general relativity which explains a number of phenomena where Einstein's theory of gravity fails. In the f(R) gravity, behaviour of the spacetime is modified as compared to that of given by the Einstein's theory of general relativity. This theory has already been explored for understanding various compact objects such as neutron stars, white dwarfs etc. and also describing evolution of the universe. Although researchers have already found the vacuum spacetime solutions for the f(R) gravity, yet there is a caveat that the metric does have some diverging terms and hence these solutions are not asymptotically flat. We show that it is possible to have asymptotically flat spherically symmetric vacuum solution for the f(R) gravity, which is different from the Schwarzschild solution. We use this solution for explaining various bound orbits around the black hole and eventually, as an immediate application, in the spherical accretion flow around it
A Fast Polynomial Chaos Expansion for Uncertainty Quantification in Stochastic Electromagnetic Problems
No full textVariations in material properties, boundary conditions, or the geometry can be expected in most electromagnetic problems. When these uncertainties in different regions of the model space are considered simultaneously, the stochastic dimensionality and the computational cost increase. Hence, uncertainty quantification in such problems is seldom attempted even though its quantification leads to a robust model. In this letter, a nonintrusive least square polynomial chaos expansion method is employed to quantify uncertainty due to stochastic variation of material properties. Using this method, the deviation from the mean performance for the transmission coefficient is obtained across the operational frequency range. The results compare well with Monte Carlo method and require just 1 & x0025; of its total computational time
AstroSat view of MAXI J1535-571: broad-band spectro-temporal features
No full textWe present the results of Target of Opportunity (ToO) observations made with AstroSat of the newly discovered black hole binary MAXI J1535-571. We detect prominent C-type quasi-periodic oscillations (QPOs) of frequencies varying from 1.85 to 2.88 Hz, along with distinct harmonics in all the AstroSat observations. We note that while the fundamental QPO is seen in the 3-50 keV energy band, the harmonic is not significant above similar to 35 keV. The AstroSat observations were made in the hard intermediate state, as seen from state transitions observed by MAXI and Swift. We attempt spectral modelling of the broad-band data (0.7-80 keV) provided by AstroSat using phenomenological and physical models. The spectral modelling using nthComp gives a photon index in the range 2.18-2.37 and electron temperature ranging from 21 to 63 keV. The seed photon temperature is within 0.19 to 0.29 keV. The high flux in 0.3-80 keV band corresponds to a luminosity varying from 0.7 to 1.07 L-Edd assuming the source to be at a distance of 8 kpc and hosting a black hole with a mass of 6 M-circle dot. The physical model based on the two-component accretion flow gives disc accretion rates as high as similar to 1 (m) over dot(Edd) and halo rate similar to 0.2 (m) over dot(Edd), respectively. The near-Eddington accretion rate seems to be the main reason for the unprecedented high flux observed from this source. The two-component spectral fitting of AstroSat data also provides an estimate of a black hole mass between 5.14 and 7.83 M-circle dot
A study of Kepler supernova remnant: angular power spectrum estimation from radio frequency data
No full textSupernova remnants (SNRs) have a variety of overall morphology as well as rich structures over a wide range of scales. Quantitative study of these structures can potentially reveal fluctuations of density and magnetic field originating from the interaction with ambient medium and turbulence in the expanding ejecta. We have used 1.5 GHz (L band) and 5 GHz (C band) VLA data to estimate the angular power spectrum C-l of the synchrotron emission fluctuations of the Kepler SNR. This is done using the novel, visibility-based, Tapered Gridded Estimator of C-l. We have found that, for l = (1.9-6.9) x 10(4), the power spectrum is a broken power law with a break at l = 3.3 x 10(4), and power-law index of -2.84 +/- 0.07 and -4.39 +/- 0.04 before and after the break, respectively. The slope -2.84 is consistent with 2D Kolmogorov turbulence and earlier measurements for the Tycho SNR. We interpret the break to be related to the shell thickness of the SNR (0.35 pc) which approximately matches l = 3.3 x 10(4) (i.e. 0.48 pc). However, for l > 6.9 x 10(4), the estimated C-l of L band is likely to have dominant contribution from the foregrounds while for C band the power-law slope -3.07 +/- 0.02 is roughly consistent with 3D Kolmogorov turbulence like that observed at large l for Cas A and Crab SNRs
Strengthening of the adhesive bond using a mixture of adhesives between dissimilar adherends in a single lap joint
No full textAdhesive bonding is the best alternative to riveting in aircraft structures but the strength of the adhesive bonded joint is low and is limited by strength of adhesive. Strengthening of adhesive bonding is an important requirement. In this work, an attempt has been made to strengthen the adhesive bonding by mixing different quantities of brittle adhesive in the ductile adhesive and vice-versa. Two different adhesives, one brittle (AV138) and another ductile (Araldite-2015) adhesive have been considered. Initially single lap joint has been constructed between the CFRP and aluminium with individual adhesives, then the mixture of adhesives have been used in the bonded region in varied proportions. The X-ray radiography and ultrasonic testing have been performed to check the quality of bonding. Uniaxial tensile tests have been conducted on the lap joints along with Digital Image Correlations (DIC) to obtain the individual and mixed adhesive bond strength. The failure patterns have been identified using optical and scanning electron microscope. These studies indicate that strengthening of the adhesive bonding achieved by mixing of two adhesives and highest bond strength obtained when the mixture of AV138 and Araldite-2015 adhesives are used in equal proportions
Composite Higgs and Dark Matter model in SU(6)/SO(6)
No full textWe consider a realisation of composite Higgs models in the context of SU(6)/SO(6) symmetry, which features a custodial bi-triplet, two Higgs doublets and dark matter candidates. This model can arise from an underlying gauge-fermion theory. The general vacuum structure is explored using the top partial compositeness to generate a special vacuum characterised by a single angle aligned with the first Higgs doublet. We present the CP and Dark Matter Z(2) parity in two different pNGB bases and analyse the spectra in the absence of tadpoles and tachyons. For the phenomenology, we discuss the constraints from electroweak precision tests and from a potentially light CP-odd singlet (other than the Dark Matter) in the model
Creep of Metallic Materials in Bending
No full textThe creep behavior of metallic materials in bending has received limited attention because of the complexity of the stress state and the nontrivial correlation with an equivalent uniaxially deformed state. Furthermore, conventional creep testing methods, i.e., under uniaxial tension and compression, which have a constant stress state during creep and well-established data interpretation protocols, are adequate for studying the creep properties of most materials. Hence, the creep properties of metallic systems have rarely been evaluated in bending. Currently, there is an increase in the demand for testing in-service components and materials having microstructures on small length scales (e.g., a few tens to hundreds of micrometers). In this situation, the material for testing is often in short supply and the dimensions of the relevant samples are very small, thus limiting the feasibility of uniaxial tests. This warrants development of alternate testing techniques, such as indentation and bending, that are ideally suited for testing small-volume samples. In particular, cantilever bending is quite attractive given the possibility of obtaining multiple data points covering a range of stresses from a single sample and the ease of sample fabrication, alignment, and gripping while testing at a small length scale. In addition, the mechanics of power-law creep in bending is well understood and developed. We present herein a review of seminal literature on power-law creep in bending, a topic which has been investigated for almost 90 years now, and an outlook on adopting bending of cantilevers as a mainstream methodology for characterizing the creep behavior of metallic systems
Regionalization of evapotranspiration using fuzzy dynamic clustering approach. Part 1: Formation of regions in India
No full textDelineation of homogeneous reference evapotranspiration (ET0) regions is essential for different applications in hydro-meteorology. In conventional regionalization approaches, lumped (time-invariant) statistics such as mean, median or interquartile range of different hydrometeorological variables are often considered as attributes to delineate regions. Information on temporal dynamics of those variables is not utilized (as it is lost in lumped statistics), which if accounted could yield better regions. To address this, a new regionalization approach is presented in fuzzy framework in this Part 1 of a two-part series. In the proposed approach, information on temporal dynamics of predictor climate variables influencing ET0 is used for regionalization, and the delineated regions are subsequently validated for homogeneity using the predictand (ET0) related information. Effectiveness of the approach is demonstrated through a case study on India, which yielded 18 regions. They are shown to be statistically more homogeneous in ET0 when compared to the existing agro-ecological zones and regions formed using global fuzzy c-means clustering method. The homogeneous ET0 regions were found to be different from homogeneous actual evapotranspiration (ETa) regions delineated over India using the fuzzy dynamic clustering approach. Various applications of the homogeneous ET0 regions formed using the proposed approach are presented in Part 2 of this series