Predictions of SUSY Masses in the Minimal SUSY GUT

The MSSM distinguishes itself from other GUT's by a successful prediction of many unrelated phenomena with a minimum number of parameters. Among them: a) Unification of the couplings constants; b)Unification of the masses; c) Proton decay; d) Electroweak symmetry breaking. A combined fit of the free parameters in the MSSM to these low energy constraints shows that the MSSM model can satisfy these constraints simultaneously. From the fitted parameters the masses of the as yet unobserved superpartners of the SM particles are predicted. The 2nd order QCD coupling constant is required to be between 0.108 and 0.132. It is shown that a top mass of $174\pm16$ GeV, as suggested recently by the CDF Collaboration, constrains the mixing angle between the Higgs doublets in the MSSM to: 1.2<\tb<5.5 at the 90% C.L.. The most probable value corresponds to \tb = 1.56, which leads to a stop mass below the top mass. In this case the stop production in $p\bar{p}$ collisions would contribute to the top signature. This could be an explanation for the large effective $t\bar{t}$ cross section observed by CDF.Comment: latex + eps fig IEKP-KA/94-0

Resilience of a semi-deciduous shrub, Cistus salvifolius, to severe summer drought and heat stress

Shrubs often form the understorey in Mediterranean oak woodlands. These shrubs are exposed to recurrent water deficits, but how they will respond to predicted future exacerbation of drought is not yet understood. The ecophysiology of the shrub Cistus salvifolius L. was studied over the summer of 2005, which was during a heat-wave superimposed on the most severe drought in the Iberian Peninsula in the last 140 years. Branch water potential fell drastically during the summer, accompanied by stomatal closure and downregulation of PSII, with a concomitant loss of chlorophyll in the leaves. A parallel increase in the ratio of light-dissipating to light-capturing pigments and the proportion of xanthophyll cycle pigments in the de-epoxidated state, along with alterations in the structure of the light harvesting complex, may have reduced the potential for damage to leaves. Substantial increases in leaf tocopherol content during high radiation may have reduced damage from free radicals. Following autumn rains, leaves of the same shrubs showed physiological recovery, indicating the resilience of this Mediterranean species, for which an extremely dry hydrological year with 45% less rainfall than average, did not prevent healthy leaf functioning in response to renewed soil moisture availability.Peer Reviewe