Observation of inter-grain Josephson effects in Y-Ba-Cu-O samples

Josephson effects have been observed in bulk samples of Y-Ba-Cu-O. The magnitude of the zero-voltage current is found to change systematically with externally applied small magnetic fields of a few mG. It is also found to vary when samples are irradiated with microwaves. These observations suggest the presence of inter-grain Josephson junctions.     

Reconstitution of Nucleosome Demethylation and Catalytic Properties of a Jumonji Histone Demethylase

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Highlights? Catalytic domain of JMJD2A (cJMJD2A) removes methyl marks in a distributive manner ? Homogeneously methylated nucleosomes were used as substrates ? Quantitative assay for nucleosome demethylation has been developed     

Cosmologies with variable gravitational constant

In 1937 Dirac presented an argument, based on the socalled large dimensionless numbers, which led him to the conclusion that the Newtonian gravitational constantG changes with epoch. Towards the end of the last century Ernst Mach had given plausible arguments to link the property of inertia of matter to the large scale structure of the universe. Mach's principle also leads to cosmological models with a variable gravitational constant. Three cosmologies which predict a variableG are discussed in this paper both from theoretical and observational points of view.     

Exchange interactions and electron pairing in superconductors — Relevance of recent experiments

The conduction electron spin resonance (CESR) studies of A-15 superconductors carried out by the authors are compared with the CESR results of Al and the measurements of the nuclear spin echo of ¹¹B in Y Rh₄B₄ and Y_1?xEr_x Rh₄B₄ observed by others. The data is discussed in the perspective and it shown that there is an overwhelming case for the conducting state to arise through exchange interactions present in the conduction band, in confirmity with the authors' earlier contentions.     

Astrophysical applications of the gravitational searchlight

The astrophysical consequences of the blue-shifted radiation emitted in the forward direction by a source moving in an equatorial orbit with radius slightly in excess of 1.5 times the Schwarzschild radius of a highly collapsed central object are examined with special reference to quasistellar objects.     

Ordering of Nb3Sn layer formed in the bronze process - I

A study of ordering of superconducting Nb₃Sn layers formed in the bronze process has been attempted for the first time. The multifilamentary composites containing 10,000 niobium filaments embedded in a bronze matrix have been diffusion reacted at various temperature for short durations of a few minutes, and the resulting changes in T_c are systematically analysed. The data are discussed in terms of a reordering kinetics model and the values of various activation energies determined are found to be consistent.     

Study of inverse a.c. Josephson effect in Y–Ba–Cu–O and Y–8a–Sr–Cu–O

Microwave induced d.c. voltage due to inverse a.c. Josephson effect has been observed across bulk samples of Y-Ba-Cu-O and Y-Ba-Sr-Cu-O. The d.c. voltage is found to vary with microwave power, frequency and also with small external magnetic fields. Although the resistivity curve of Y-Ba-Cu-O does not show any appreciable resistance drop around 230 K, the microwave induced d.c. voltage due to the inverse a.c. Josephson effect has been found to exist upto 230 K. The resistivity behaviour of Y-Ba-Sr-Cu-O shows a sharp resistivity drop above 230 K. In this sample the inverse Josephson effect is found to exist upto +26 °C, indicating the presence of a phase having a superconducting onset around this temperature.     

On orders Solely of Abelian Groups II

Let C'(x) denote the number of integers n x such that thereis no non-abelian group of order n, but there exists a non-cyclicgroup of order n. Here it is shown that C' (x) , x , where denotes Euler's constant.