Thermoelectrics (TE) are solid state systems which convert heat toelectricity or do active cooling by passing a current through it. They canbe used for power generation or cooling devices. Although TE have been around for more than 100 years they are not widely used because of theirlow efficiency. The efficiency of a TE is determined by a dimensionlessfactor ZT called the figure of merit which depends on both electronic andphononic properties of the solid. Due to competing physical effects it hasbeen very difficult to make ZT much larger than 1. However, in recentyears several theoretical ideas (electron crystal phonon glass, transportin reduced dimensionality, dissipation-less energy transport throughenergy filtering etc ) have been proposed to increase ZT beyond 1. Severalof these ideas have been implemented in designing novel materials and someof these show a ZT value ~2. These concepts and how they operate in thesematerials will be discussed. Conditions for dissipation-less energytransport which occurs in a perfect thermoelectric will be explained.Attempts to design such materials will be described.* Work partly supported by a ONR-MURI grant.

Physicists and chemists have been interested in devising materials and methods to induce ferromagentic order in several oxides. Such studies provide an understanding of the fundamental mechanisms involved. In addition, these materials are candidates for potential applications in magnetic memories, sensors etc. Typical examples are ferrites and garnets. However there are other oxides which show novel properties. In this talk, I will describe three such classes of materials – double layer spin cluster glass manganites that exhibit a resistance drop of 1 million in moderate fields but at low temperatures, frustrated pyrochlores where ferromagentic order is induced by proper selection of substitution and undoped indium oxide in which charge carriers seem to be spin polarized.

Our understanding of orgin of the universe is mainly in frame work of Big-Bang models. Stringent constraints on these models come from light element abundances and thermal evolution of cosmic microwave background. Development of structures in the Universe very much depends on the mass density of different components and their redshift evolution.Development of fundamental physics relies on the constancy of various fundamental quantities such as the fine structure constant. Detecting or constraining the possible time variations of these fundamental physical quantities is an important step toward a complete understanding of basic physics.High quality absorption lines seen in the spectra of distant QSOs allow one to address all the above listed issues. In this talkwe will present the overview of the approach and highlightsome very recent results based on observations taken with VeryLarge Telescope (VLT) in Chile and Giant meterwave radio telescopenear Pune.

We review the long-standing arguments in favor of stable exotic mesons with two heavy quarks and two light antiquarks. For a flavor independent interaction, as suggested by QCD, this mass configuration is favored as compared to equal-mass or hidden-charm configurations, in complete analogy with the pattern observed in atomic physics when the hydrogen molecule is compared to the positronium molecule or to the hydrogen-antihydrogen system.We then present the results of a recent model calculation, inspired by the strong coupling limit of QCD: the linear potential for a quark-antiquark pair in mesons is generalized as a Y-shape interaction for baryons and a Steiner tree for tetraquarks. The four-body problem is then solved by an accurate variational method. An analytic upper bound is also obtained, which confirms the numerical results in the limit of large values for the quark mass ratio.