Studies on plasma treatment and priming of seeds of bell pepper (Capsicum annuum L.)

The present investigation was carried out at Dr. Y.S. Parmar University of Horticulture and Forestry, Nauni, Solan during the year 2014 -2015 to study the “Effect of cold plasma treatment and priming on bell pepper (Capsicum annuum L. cultivar California Wonder) for seed germination and seedling vigour. The seeds were ex-posed to various durations of oxygen plasma treatment using glow discharge technique at FCIPT, Institute for Plas-ma Research, Gandhinagar, Gujarat, India. Seeds were pre-treated with power of 100 W for treatment durations of 0, 3, 6, 9, 12, 15 minutes for 0, 4, 8 and 12 month durations. The changes in surface morphology of plasma treated seeds were studied by Scanning Electron Microscopy (SEM) and Contact Angle Goniometer. Along with plasma treatment, seeds were also treated with standard priming method i.e osmoprimng for comparison. Results showed that plasma treatment alone as well as in combination with osmoprimng up to 6 minutes duration had positive effects on seed germination and seedling vigour. Germination and vigour indices significantly increased by 21.75% and 90.71% respectively. Characteristics of germination percentage, speed of germination, seedling vigour index-I & II, significantly increased by 13.92%, 1.39 cm, 0.38 mg, 322.07 respectively, compared with control. And it was found that immediately after plasma exposure the germination (84.41%) and vigour (228.50) was highest and it was reduced to (73.54%) and (174.27) after 12 months of storage. These results indicated that cold plasma treatment might promote the growth and modify the speed of germination i.e. higher speed of germination was observed in seeds exposed to plasma treat-ment for 6 minutes (59.82%), whereas, lowest germination speed (40.76%) was observed in untreated control

Is it safe to vaccinate children against varicella while they're in close contact with a pregnant woman?

All healthy children without evidence of immunity to varicella who are living in a household with a susceptible pregnant woman should be vaccinated (strength of recommendation [SOR]: C, expert opinion). The risk of transmission of vaccine virus to household contacts is very low (SOR: B, observational studies). Transmission is higher, but still rare, among contacts of immunocompromised vaccinees (SOR: B, observational studies). Varicella infection has not been reported in unborn babies of women who had contact with a recently vaccinated person

The Immirzi Parameter as an Instanton Angle

The Barbero-Immirzi parameter is a one parameter quantization ambiguity underpinning the loop approach to quantum gravity that bears tantalizing similarities to the theta parameter of gauge theories such as Yang-Mills and QCD. Despite the apparent semblance, the Barbero-Immirzi field has resisted a direct topological interpretation along the same lines as the theta-parameter. Here we offer such an interpretation. Our approach begins from the perspective of Einstein-Cartan gravity as the symmetry broken phase of a de Sitter gauge theory. From this angle, just as in ordinary gauge theories, a theta-term emerges from the requirement that the vacuum is stable against quantum mechanical tunneling. The Immirzi parameter is then identified as a combination of Newton's constant, the cosmological constant, and the theta-parameter.Comment: 24 page

Local Void vs Dark Energy: Confrontation with WMAP and Type Ia Supernovae

It is now a known fact that if we happen to be living in the middle of a large underdense region, then we will observe an "apparent acceleration", even when any form of dark energy is absent. In this paper, we present a "Minimal Void" scenario, i.e. a "void" with minimal underdensity contrast (of about -0.4) and radius (~ 200-250 Mpc/h) that can, not only explain the supernovae data, but also be consistent with the 3-yr WMAP data. We also discuss consistency of our model with various other measurements such as Big Bang Nucleosynthesis, Baryon Acoustic Oscillations and local measurements of the Hubble parameter, and also point out possible observable signatures.Comment: Minor numerical errors and typos corrected, references adde

An inhomogeneous universe with thick shells and without cosmological constant

We build an exact inhomogeneous universe composed of a central flat Friedmann zone up to a small redshift $z_1$, a thick shell made of anisotropic matter, an hyperbolic Friedmann metric up to the scale where dimming galaxies are observed ($z\simeq 1.7$) that can be matched to a hyperbolic Lema\^{i}tre-Tolman-Bondi spacetime to best fit the WMAP data at early epochs. We construct a general framework which permits us to consider a non-uniform clock rate for the universe. As a result, both for a uniform time and a uniform Hubble flow, the deceleration parameter extrapolated by the central observer is always positive. Nevertheless, by taking a non-uniform Hubble flow, it is possible to obtain a negative central deceleration parameter, that, with certain parameter choices, can be made the one observed currently. Finally, it is conjectured a possible physical mechanism to justify a non-uniform time flow.Comment: Version published in Class. Quantum gra

"Swiss-Cheese" Inhomogeneous Cosmology & the Dark Energy Problem

We study an exact swiss-cheese model of the Universe, where inhomogeneous LTB patches are embedded in a flat FLRW background, in order to see how observations of distant sources are affected. We find negligible integrated effect, suppressed by (L/R_{H})^3 (where L is the size of one patch, and R_{H} is the Hubble radius), both perturbatively and non-perturbatively. We disentangle this effect from the Doppler term (which is much larger and has been used recently \cite{BMN} to try to fit the SN curve without dark energy) by making contact with cosmological perturbation theory.Comment: 35 pages, 6 figure

LTB solutions in Newtonian gauge: from strong to weak fields

Lemaitre-Tolman-Bondi (LTB) solutions are used frequently to describe the collapse or expansion of spherically symmetric inhomogeneous mass distributions in the Universe. These exact solutions are obtained in the synchronous gauge where nonlinear dynamics (with respect to the FLRW background) induce large deviations from the FLRW metric. In this paper we show explicitly that this is a gauge artefact (for realistic sub-horizon inhomogeneities). We write down the nonlinear gauge transformation from synchronous to Newtonian gauge for a general LTB solution using the fact that the peculiar velocities are small. In the latter gauge we recover the solution in the form of a weakly perturbed FLRW metric that is assumed in standard cosmology. Furthermore we show how to obtain the LTB solutions directly in Newtonian gauge and illustrate how the Newtonian approximation remains valid in the nonlinear regime where cosmological perturbation theory breaks down. Finally we discuss the implications of our results for the backreaction scenario.Comment: 17 page