Partial data inverse problems for the Hodge Laplacian

We prove uniqueness results for a Calderon type inverse problem for the Hodge Laplacian acting on graded forms on certain manifolds in three dimensions. In particular, we show that partial measurements of the relative-to-absolute or absolute-to-relative boundary value maps uniquely determine a zeroth order potential. The method is based on Carleman estimates for the Hodge Laplacian with relative or absolute boundary conditions, and on the construction of complex geometric optics solutions which reduce the Calderon type problem to a tensor tomography problem for 2-tensors. The arguments in this paper allow to establish partial data results for elliptic systems that generalize the scalar results due to Kenig-Sjostrand-Uhlmann.Comment: 54 pages, updated versio

A method for the determination of trace metals in carbon by atomic absorption spectroscopy

The object of this research was to develop an accurate, rapid and economical method for determining trace amounts of metals in carbons, especially in activated carbons designed as gas adsorbents. More specifically, the investigation was directed primarily to the determination of K, Ca, and Fe in Carbon

What prospective young workers should know about labor relations, according to the views of selected labor leaders

Thesis (M.A.)--Boston University, 1949. This item was digitized by the Internet Archive

Study of the certification of secondary school principals in the United States

Thesis (M.A.)--Boston University This item was digitized by the Internet Archive

Whenever one surface is moved over another there is always friction which always results in the transformation of some of the mechanical energy of the moving object into heat energy and in the wearing away of some of each surface.

Thesis (Ed.M.)--Boston Universit

What prospective young workers should know about labor relations, according to the views of selected labor leaders

Thesis (M.A.)--Boston University, 1949. This item was digitized by the Internet Archive

You Asked Us, Gal

Men don\u27t like to look a gift horse in the mouth, but then...... You asked us about Christmas presents

On the acquisition of either and too

This paper presents an experimental investigation of how English-learning children acquire the additive discourse particles either and too. In the target grammar these items exhibit near-complementary distribution conditioned on the polarity of their host sentence. The path leading to that grammar appears to be rather intricate. We present comprehension data showing that for an extended period of time (3–5 ya) learners find both items acceptable in both polarity environments, exhibiting only a weak adult-like tendency of preferring either in negative and too in positive sentences. At 6 ya, their grammar appears categorical wrt. either in that they no longer tolerate it in positive sentences while still exhibiting only a weak dispreference for too in negative environments. These findings are even more striking in the context of production data. We find that child-directed speech is essentially categorical, providing unambiguous evidence for the adult grammar. Moreover, we find essentially categorical, adult-like use of either and too in child production from the earliest stage of development. These observations raise a number of challenges for theories of either and too and for approaches to learning focus particles more generally. Perhaps most strikingly, the protracted insensitivity of the learner's grammar to accumulation of unambiguous evidence constitutes a novel argument from the abundance of evidence for encapsulated learning