Standard (level one) heterotic string models with standard model gauge group predict the unification of SU(3) and SU(2) gauge couplings whereas the U(1) factor is unified modulo an unknown normalization factor k1. On the other hand the unification mass is known. I argue that this situation is quite analogous (though opposite) to that in SUSYGUTs in which the U(1) normalization is known (k1 = 5/...

The benefits of bioluminescence for nonsymbiotic marine bacteria have not been elucidated fully. One of the most commonly cited explanations, proposed more than 30 y ago, is that bioluminescence augments the propagation and dispersal of bacteria by attracting fish to consume the luminous material. This hypothesis, based mostly on the prevalence of luminous bacteria in fish guts, has not been te...

We all have bacteria in our guts, and so do all animals, including birds. These bacteria are good for us in many ways and help to digest the food we eat. We often see similar groups of bacteria in the guts of animals that are related to each other. But it is not clear why this is. It could be because similar animals eat similar foods, or maybe because of other similarities between the related a...

Recently, new possibilities of Grand Unified Theories (GUTs) in the context of higher dimensional field theories have extensively been explored to avoid common problems of four-dimensional GUTs. The GUT symmetry breaking scale is naturally given by the inverse length of the extra dimensions, but the origin of the weak scale is still a mystery. In this paper, we propose a higher dimensional scen...

Gauge-Yukawa Unification (GYU) is a renormalization group invariant functional relation among gauge and Yukawa couplings which holds beyond the unification point in Grand Unified Theories (GUTs). We present here various models where GYU is obtained by requiring the principles of finiteness and reduction of couplings. We examine the consequences of these requirements for the low energy parameter...

Two groups have shown that, as in macaques infected with simian immunodeficiency virus (SIV), intestinal CD4(+) T cells are selectively and rapidly depleted in the intestine of HIV-infected patients. Depletion of intestinal CD4(+) T cells occurred at all stages of infection regardless of highly active antiretroviral therapy (HAART). Here we discuss the important implications of these papers for...