Dynamic response for thermal control and measurement and fast radiation thermometry

A preliminary evaluation was made by ORNL of a two-color ratio pyrometer (TCRP) for temperature control in the Modular Electromagnetic Levitation (MEL) experiment. A discussion was presented by Eric Spjut at the 1987 NASA Non-Contact Temperature Measurement Workshop (NASA Conf. Publ. 2503, pp. 182-213) in which he described the non-linear characteristics of the time response of TCPs. Researchers replicated his model and results and note that the non-linear response behavior is minimized for small temperature steps at high temperatures. They then used the predicted response in a model for a proportional or integral feedback controller and predicted the control characteristics for heating and cooling a 5-mm diameter sphere of niobium at high (1500 to 2750 K) temperatures. The analysis shows that for a slow (25-ms) time response for a commercial RCRP, overshoots of several hundred kelvins will result from a 100-K decrease in the setpoint, and temperature tracking errors of 14 to 45 K will occur for control temperature ramps of 1000K/s. For a fast (greater than 0.1 ms) time response, the overshoot and ramp response errors are largely eliminated

A Bibliography of the Rhizocephala (Crustacea: Cirripedia)

A bibliography of parasitic barnacles of the suborder Rhizocephala, including 490 titles, is presented. Scientific works from 1787 to present are listed

Procedures for Eradication of Hydrozoan Pests in Closed-System Mysid Culture

An unidentified species of hydrozoan in the family Eirenidae was inadvertently transported to the Laboratory with a stock of Mysidopsis bahia. The hydrozoan competed for food, ate the young mysids, and subsequently reproduced extensively. Hermit crabs provided minimal control. A detailed transfer procedure for the mysids eliminated the hydrozoans from cultures; hydrozoans were eradicated from tanks after removal of mysids by using 1:1200 formalin, hot water, and Clorox

Procedures for Eradication of Hydrozoan Pests in Closed-System Mysid Culture

An unidentified species of hydrozoan in the family Eirenidae was inadvertently transported to the Laboratory with a stock of Mysidopsis bahia. The hydrozoan competed for food, ate the young mysids, and subsequently reproduced extensively. Hermit crabs provided minimal control. A detailed transfer procedure for the mysids eliminated the hydrozoans from cultures; hydrozoans were eradicated from tanks after removal of mysids by using 1:1200 formalin, hot water, and Clorox

Paradoxical perception of surfaces in the Shepard tabletop illusion

The Shepard tabletop illusion, consisting of different perspective embeddings of two identical parallelograms as tabletops, affords a profound difference in their perceived surface shapes. My analysis reveals three further paradoxical aspects of this illusion, in addition to its susceptibility to the ‘inverse perspective illusion’ of the implied orthographic perspective of the table images. These novel aspects of the illusion are: a paradoxical slant of the tabletops, a paradoxical lack of perceived depth, and a paradoxical distortion of the length of the rear legs. The construction of the illusion resembles scenes found in ancient Chinese scroll paintings, and an analysis of the source of the third effect shows that the interpretation in terms of surfaces can account for the difference in treatment of the filled-in versus open forms in the Chinese painting from more than 1000 years ago

Graphene field-effect transistors based on boron nitride gate dielectrics

Graphene field-effect transistors are fabricated utilizing single-crystal hexagonal boron nitride (h-BN), an insulating isomorph of graphene, as the gate dielectric. The devices exhibit mobility values exceeding 10,000 cm2/V-sec and current saturation down to 500 nm channel lengths with intrinsic transconductance values above 400 mS/mm. The work demonstrates the favorable properties of using h-BN as a gate dielectric for graphene FETs.Comment: 4 pages, 8 figure

Defined contribution pension plans : can the real estate industry tap this growing pool of capital?

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1997 [first author]; and, Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1996 [second author].Includes bibliographical references.by Robert L. Johnson, Jr. & Peter R. Shepard.M.S

Breast carcinoma cells re-express E-cadherin during mesenchymal to epithelial reverting transition

<p>Abstract</p> <p>Background</p> <p>Epithelial to mesenchymal transition (EMT), implicated as a mechanism for tumor dissemination, is marked by loss of E-cadherin, disruption of cell adhesion, and induction of cell motility and invasion. In most intraductal breast carcinomas E-cadherin is regulated epigenetically via methylation of the promoter. E-cadherin expression is therefore dynamic and open to modulation by the microenvironment. In addition, it has been observed that metastatic foci commonly appear more differentiated than the primary tumor, suggesting that cancer cells may further undergo a mesenchymal to epithelial reverting transition (MErT) in the secondary organ environment following the EMT that allows for escape.</p> <p>Results</p> <p>We first examined E-cadherin expression in primary breast tumors and their corresponding metastases to liver, lung and brain and discovered that 62% (10/16) of cases showed increased E-cadherin expression in the metastases compared to the primaries. These observations led to the question of whether the positive metastatic foci arose from expansion of E-cadherin-positive cells or from MErT of originally E-cadherin-negative disseminated cells. Thus, we aimed to determine whether it was possible for the mesenchymal-like MDA-MB-231 breast cancer cells to undergo an MErT through the re-expression of E-cadherin, either through exogenous introduction or induction by the microenvironment. Ectopic expression of full-length E-cadherin in MDA-MB-231 cells resulted in a morphological and functional reversion of the epithelial phenotype, with even just the cytosolic domain of E-cadherin yielding a partial phenotype. Introduction of MDA-MB-231 cells or primary explants into a secondary organ environment simulated by a hepatocyte coculture system induced E-cadherin re-expression through passive loss of methylation of the promoter. Furthermore, detection of E-cadherin-positive metastatic foci following the spontaneous metastasis of MDA-MB-231 cells injected into the mammary fat pad of mice suggests that this re-expression is functional.</p> <p>Conclusions</p> <p>Our clinical observations and experimental data indicate that the secondary organ microenvironment can induce the re-expression of E-cadherin and consequently MErT. This phenotypic change is reflected in altered cell behavior and thus may be a critical step in cell survival at metastatic sites.</p