INTRODUCTION: Nearly 75% of breast reconstruction procedures performed by ASPS members in 2015 involved tissue expanders. Despite the advantages of expander-based reconstruction, complications are common and can require early removal of the tissue expander. Patient preference and oncologic factors may also prompt unanticipated removal of the tissue expander. We present our experience with tissu...

The effect of the internal heat exchanger (IHE) on the performance of the transcritical carbon dioxide refrigeration cycle with an expander is analyzed theoretically on the basis of the first and second laws of thermodynamics. The possible parameters affecting system efficiency such as heat rejection pressure, gas cooler outlet temperature, evaporating temperature, expander isentropic efficienc...

A new type of expander-compressor system called Cross Vane expander-compressor (CVEC) was introduced. This device replaces the expansion valve and compressor in conventional refrigeration systems to reduce the energy consumption and improve the coefficient of performance (COP) of the system. As opposed to many expander-compressor systems in the literature, whereby a separated expander is couple...

BACKGROUND To define the dosimetric coverage of level I/II axillary volumes and the lung volume irradiated in postmastectomy radiotherapy (PMRT) following tissue expander placement. METHODS AND MATERIALS Twenty-three patients were identified who had undergone postmastectomy radiotherapy with tangent only fields. All patients had pre-radiation tissue expander placement and expansion. Thirteen ...

A common sequence for performing staged tissue expander breast reconstruction is to immediately insert a tissue expander, complete expansion before radiotherapy, and then perform the definitive reconstruction after radiotherapy is complete. This study evaluates the outcomes of this treatment regimen in 237 patients over a 10-year period at Northwestern Memorial Hospital. Overall, 62% of the pat...

We present new infinite families of expander graphs of vertex degree 4, which is the minimal possible degree for Cayley graph expanders. Our first family defines a tower of coverings (with covering indices equals 2) and our second family is given as Cayley graphs of finite groups with very short presentations with only 2 generators and 4 relations. Both families are based on particular finite q...

The explicit construction of infinite families of d-regular graphs which are Ramanujan is known only in the case d 1 is a prime power. In this paper, we consider the case when d 1 is not a prime power. The main result is that by perturbing known Ramanujan graphs and using results about gaps between consecutive primes, we are able to construct infinite families of ‘‘almost’’ Ramanujan graphs for...

We derive a new upper bound for the diameter of a k-regular graphG as a function of the eigenvalues of the adjacency matrix. Namely, supposethe adjacency matrix of G has eigenvalues AI , A2 .••.• An with lAd:::: IA21 ::::... :::: IAnl where AI = k, A = IA21. Then the diameter D(G) must satisfy D(G) :::; rlog(n 1)f1og(k/A)l. We wilJ consider families of graphs whose eigenvalues can b...

We consider the standard semi-direct product AoB of finite groups A,B. We show that with certain choices of generators for these three groups, the Cayley graph of A o B is (essentially) the zigzag product of the Cayley graphs of A and B. Thus, using the results of [RVW00], the new Cayley graph is an expander if and only if its two components are. We develop some general ways of using this const...