Feasibility of cardiac cryoablation using a transvenous steerable electrode catheter

BACKGROUND AND PURPOSE: Accurate contouring of the clinical target volume (CTV) is a fundamental prerequisite for successful conformal radiotherapy of prostate cancer. The purpose of this study was to investigate intra- and inter-observer variability in contouring prostate (P) and seminal vesicles (SV) and its impact on conformal treatment planning in our working conditions. MATERIALS AND METHODS: Inter-observer variability was investigated by asking five well-trained radiotherapists of contouring on CT images the P and the SV of six supine-positioned patients previously treated with conformal techniques. Short-term intra-observer variability was assessed by asking the radiotherapists to contour the P and SV of one patient for a second time, just after the first contouring. The differences among the inserted volumes were considered for both intra- and inter-observer variability. Regarding intra-observer variability, the differences between the two inserted contours were estimated by taking the relative differences in correspondence to the CT slices on BEV plots (antero-posterior and left-right beams). Concerning inter-observer variability, the distances between the internal and external envelopes of the inserted contours (named projected diagnostic uncertainties or PDUs) and the distances from the mean inserted contours (named mean contour distances or MCDs) were measured from BEV plots (i.e. parallel to the CT slices). RESULTS: Intra-observer variability was relatively small (the average percentage variation of the volume was approximately 5%; SD of the differences measured on BEV plots within 1.8 mm). Concerning inter-observer variability, the percentage SD of the inserted volumes ranged from 10 to 18%. Differences equal to 1 cm in the cranio-caudal extension of P + SV were found in four out of six patients. The largest inter-observer variability was found when considering the anterior margin in the left-right beam of P top (MCD = 7.1 mm, 1 SD). Relatively high values for MCDs were also found for P bottom, for the posterior and lateral margins of P top (2.6 and 3.1 mm, respectively, I SD) and for the anterior margin of SV (2.8 mm, 1 SD). Relatively small values were found for P central (from 1.4 to 2.0 mm, 1 SD) and the posterior margin of SV (1.5 mm, 1 SD). CONCLUSIONS: The application of larger margins taking inter-observer variability into account should be taken into consideration for the anterior and the lateral margins of SV and P top and for the lateral margin of P. The impact of short-term intra-observer variability does not seem to be relevant.     

Structural effects of the binding of GTP to the wild-type and oncogenic forms of the ras-gene-encoded p21 proteins

Molecular dynamics calculations have been performed to determine the average structures of ras-gene-encoded p21 proteins bound to GTP, i.e., the normal (wild-type) protein and two oncogenic forms of this protein, the Val 12- and Leu 61-p21 proteins. We find that the average structures for all of these proteins exhibit low coordinate fluctuations (which are highest for the normal protein), indicating convergence to specific structures. From previous dynamics calculations of the average structures of these proteins bound to GDP, major regional differences were found among these proteins [Monaco et al. (1995), J. Protein Chem., in press]. We now find that the average structures of the oncogenic proteins are more similar to one another when the proteins are bound to GTP than when they are bound to GDP [Monaco et al. (1995), J. Protein Chem., in press]. However, they still differ in structure at specific amino acid residues rather than in whole regions, in contradistinction to the results found for the p21-GDP complexes. Two exceptions are the regions 25-32, in an alpha-helical region, and 97-110. The two oncogenic (Val 12- and Leu 61-) proteins have similar structures which differ significantly in the region of residues 97-110. This region has recently been identified as being critical in the interaction of p21 with kinase target proteins. The differences in structure between the oncogenic proteins suggest the existence of more than one oncogenic form of the p21 protein that can activate different signaling pathways.     

Microwave and far-infrared propagation in conductive microstructured composites

In a recent publication [T.E. Huber, L. Luo, Appl. Phys. Lett. 70 (1997) 2502.] we discussed a structural enhancement of the electromagnetic transmission in composites. We showed that densely packed arrays (76% volume fraction) of 10 μm diameter parallel indium wires exhibit an enhanced transmission, of 10³, relative to an indium foil of equal thickness for far-infrared (10 cm⁻¹ < k < 80 cm⁻¹) propagating along the wire length. The absorption increases as k^{0.45 ± 0.07} and is explained by the dynamic Maxwell-Gannett model, which includes eddy current dissipation. It is of considerable practical interest to extend the range of application of these composite properties to the microwave domain. Here we will discuss recent measurements of the transmission of microwaves in wire array composites in the 8–12 GHz frequency range.     

Emission characteristics of some dilute tungsten alloys

The effective work functions of nine tungsten-base alloys were measured. The second constituents were: 1) 5 pct Re, 2) 15 pct Re, 3) 2.5 pct Os, 4) 5 pct Os, 5) 1 pct Ir, 6) 2 pct Ir, 7) 5 pct Ta, 8) 10 pct Ta, and 9) 26 pct Ta. Work functions were determined from vacuum emission vehicle and thermionic emission microscope measurements. Mosaics of each surface were produced from the microscope which show the grain structure of the alloys and some anomalous emission areas. Some exceptionally high bare work functions were observed from samples with small alloy additions. For example, the work function of W1 pct Ir was 5.3 eV. DEAN LEO JACOBSON, formerly Section Manager, Electro-Optical Systems, Division of Xerox Corp., Pasadena, Calif.     

Phenomenal, ideal, and projected conceptions of self.

The relationship between the phenomenal, ideal, and projected self concepts in normal, neurotic, and paranoid schizophrenic Ss is investigated by comparing a self rating of present personal characteristics (phenomenal self) and ideal personal characteristics (ideal self) with the TAT hero characteristics of each S based on five TAT stories (projective self). The results indicate that normals have positive attitudes towards the self on a realistic basis. The paranoid schizophrenic group revealed positive self attitudes which were reflective of self enhancing defenses and were based on unrealistic self appraisal. The neurotic group maintained negative self attitudes based on a realistic perception of disturbances within the self. (PsycINFO Database Record (c) 2010 APA, all rights reserved)