In this paper we give a geometric characterization of the cones of toric varieties that are complete intersections. In particular, we prove that the class of complete intersection cones is the smallest class of cones which is closed under direct sum and contains all simplex cones. Further, we show that the number of the extreme rays of such a cone, which is less than or equal to 2n − 2, is exac...

PURPOSE To determine the visual pigment content of the rods and cones of the guinea pig (Cavia porcellus) and to quantify the level of coexpression of pigments within individual cones. METHODS Microspectrophotometry was used to measure the absorbance spectrum of visual pigments in individual rods and cones from three retinal regions: dorsal, ventral, and a subequatorial transition zone. Parti...

Spectral sensitivities of photoreceptors in the turtle (Geoclemys) retina were studied by intracellular recording, and each cell was filled with Lucifer yellow (LY). Photoreceptors were classified into seven morphological types: rod, four types of single cones, and two members of a double cone. Single cones contained one of four different oil droplets: red, pale-green, orange, and clear. Double...

We explicitly calculate characteristic functions of cones of generalized polynomials corresponding to Chebyshev systems on intervals of the real line and the circle. Thus, in principle, we calculate homogeneous self-concordant barriers for this class of cones. This class includes almost all "cones of squares" considered in 5]. Our construction, however, does not use this structure and is applic...

We show that closed convex cones, having bounded order intervals (in particular weakly complete proper convex cones) in conuclear spaces, are generated by their extreme rays. An analogue of Choquet's theorem is obtained for these cones, as well as for the conuclear cones deened in this article. Well-capped cones are conuclear. The main tool is Choquet's notion of conical measure, of which we pr...

• unify, and generalize seemingly disparate, classical sufficient conditions: polyhedrality of the cone, and “Slater” type conditions; • are necessary and sufficient, when the dual cone belongs to a class, that we call nice cones. Nice cones subsume all cones amenable to treatment by efficient optimization algorithms: for instance, polyhedral, semidefinite, and p-cones. • provide similarly attr...

In the tiger salamander retina, visual signals are transmitted to the inner retina via six morphologically distinct types of photoreceptors: large/small rods, large/small single cones, and double cones composed of principal and accessory members. The objective of this study was to determine the morphology of these photoreceptors and their synaptic interconnection with bipolar cells and horizont...

We have labeled the growth cones of retinal ganglion cell axons with HRP in intact mouse embryos. This has allowed us to visualize growth cone morphology during outgrowth along an entire CNS pathway from origin to target; to ask whether growth cone forms, and thus behaviors, differ at various points along the pathway; and to study the relationships of growth cones with the cellular environment....

We have previously used retinal and sympathetic explants to show that growth cones recognize and retract from specific neurites in culture (Kapfhammer et al., 1986). In an effort to determine the generality of this phenomenon and to see how many different neurite labels can be detected by it, we have studied interactions between individual growth cones and neurites extending from a variety of n...