Howard Jacobowitz

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Geometric sensitivity for single photon emission computerized tomography (SPECT) is given by a double integral over the detection plane. It would be useful to be able to explicitly evaluate this quantity. This paper shows that the inner integral can be evaluated in the situation where there is no gamma ray penetration of the material surrounding the pinhole(More)
This paper studies a generic class of sub-bundles of the complexified tangent bundle. Involutive, generic structures always exist and have Levi forms with only simple zeroes. For a compact, orientable three-manifold the Chern class of the sub-bundle is mod 2 equivalent to the Poincaré dual of the characteristic set of the associated system of linear partial(More)
We study the interrelation among pseudohermitian and Lorentzian geometry as prompted by the existence of the Fefferman metric. Specifically for any nondegenerate CR manifold M we build its b-boundary Ṁ . This arises as a S quotient of the bboundary of the (total space of the canonical circle bundle over M endowed with the) Fefferman metric. Points of Ṁ are(More)
We consider a first order linear partial differential operator of principal type on a closed connected orientable two-dimensional manifold sending sections of one complex line bundle to sections of another. We prove that the assumption of global hypoellipticity of the operator implies a relation between the degrees of the line bundles and the Euler(More)
1480 NOTICES OF THE AMS VOLUME 42, NUMBER 12 T he theory of functions (what we now call the theory of functions of a complex variable) was one of the great achievements of nineteenth century mathematics. Its beauty and range of applications were immense and immediate. The desire to generalize to higher dimensions must have been correspondingly irresistible.(More)
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