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A Fano variety is a projective variety whose anticanonical class is ample. A 2-dimensional Fano variety is called a Del Pezzo surface. In higher dimensions, attention originally centered on smooth Fano 3-folds, but singular Fano varieties are also of considerable interest in connection with the minimal model program. The existence of Kähler-Einstein metrics on Fano varieties has also been explored, see [Bourguignon97] for a summary of the main results. Here again the smooth case is of primary interest, but Fano varieties with quotient singularities and their orbifold metrics have also been studied.In any given dimension there are only finitely many families of smooth Fano varieties [Campana91, Nadel91, KoMiMo92], but very little is known about them in dimensions 4 and up. By allowing singularities, infinitely many families appear and their distribution is very poorly understood.A natural experimental testing ground is given by hypersurfaces and complete intersections in weighted projective spaces. These can be written down rather explicitly, but they still provide many more examples than ordinary projective spaces. Experimental lists of certain 3-dimensional complete intersections were compiled by [Fletcher89]. In connection with Kähler-Einstein metrics, the 2-dimensional cases were first investigated in [Demailly-Kollár99] and later in .It is also of interest to study Calabi-Yau hypersurfaces and hypersurfaces of general type in weighted projective spaces. [Fletcher89] contains some lists with terminal singularities.The aim of this paper is threefold. First, we determine the complete list of anticanonically embedded quasi smooth Fano hypersurfaces in weighted projective 4-spaces. There are 48 infinite series and 4442 sporadic examples (7). As a consequence we obtain that the Reid-Fletcher list (cf. [Fletcher89, II.6.6]) of 95 types of anticanonically embedded quasi smooth terminal Fano threefolds in weighted projective 4-spaces is complete (11).Second, we prove that many of these Fano hypersurfaces admit a Kähler-Einstein metric (15). We also study the nonexistence of tigers on these Fano 3-folds (in the colorful terminology of ).

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Pharmacologic profiling of serotonin (5HT) receptors of bovine lateral saphenous vein has shown that cattle grazing endophyte-infected (Neotyphodium coenophialum) tall fescue (Lolium arundinaceum) have altered responses to ergovaline, 5HT, 5HT2A, and 5HT7 agonists. To determine if 5HT receptor activity of tall fescue alkaloids is affected by grazing endophyte-free (EF), wild-type [Kentucky-31 (KY31)], novel endophyte AR542-infected (MAXQ), or novel endophyte AR584-infected (AR584) tall fescue, contractile responses of lateral saphenous veins biopsied from cattle grazing these different fescue-endophyte combinations were evaluated in presence or absence of antagonists for 5HT2A (ketanserin) or 5HT7 (SB-269970) receptors. Biopsies were conducted over 2 yr on 35 mixed-breed steers (361.5 ± 6.3 kg) grazing EF (n = 12), KY31 (n = 12), MAXQ (n = 6), or AR584 (n = 5) pasture treatments (3 ha) between 84 and 98 d (Yr 1) or 108 to 124 d (Yr 2). Segments (2 to 3 cm) of vein were surgically biopsied, sliced into 2- to 3-mm cross-sections, and suspended in a myograph chamber containing 5 mL of oxygenated Krebs-Henseleit buffer (95% O2/5% CO2; pH = 7.4; 37°C). Veins were exposed to increasing concentrations of 5HT, ergovaline, and ergovaline + 1 × 10(-5) M ketanserin or + 1 × 10(-6) M SB-269970 in Yr 1. In Yr 2, ergotamine and ergocornine were evaluated in presence or absence of 1 × 10(-5) M ketanserin. Contractile response data were normalized to a reference addition of 1 × 10(-4) M norepinephrine. In Yr 1, contractile response to 5HT and ergovaline were least (P < 0.05) in KY31 pastures and the presence of ketanserin greatly reduced (P < 0.05) the response to ergovaline in all pastures. However, presence of SB-269970 did not (P = 0.91) alter contractile response to ergovaline. In Yr 2, there was no difference in contractile response to ergotamine (P = 0.13) or ergocornine (P = 0.99) across pasture treatments, but ketanserin reduced (P < 0.05) the contractile response to both alkaloids. The 5HT2A receptor is involved in alkaloid-induced vascular contraction and alkaloid binding may be affected by exposure to different endophyte-fescue combinations.