The morphological, physiological, and nutritional characteristics and the deoxyribonucleic acid (DNA) base compositions of 39 strains of SpirilZum (including the available type strains) were determined. A uniform methodology provided a basis for comparison of the strains. The results, together with previous serological data and with previous results for two strains of Spirillum volutans, indicate that the present genus Spirillum should be divided into three genera, with the original name being restricted to obligately microaerophilic freshwater forms having a large cell diameter and a DNA base composition of 36 to 38 mol % guanine + cytosine (G + C). This genus would contain at present only one species, the type species, S . uolutans. The generic name Aquaspirillum is proposed for the aerobic, freshwater forms having a DNA base composition of 49 to 65 mol % G + C. Although Spirillum Ehrenberg 1832 is one of significance, except for Spirillum minor, the the oldest bacterial generic names and although causative agent of one of the forms of rat-bite spirilla are widespread in freshwater and marine fever in man (3, 8, 29); (ii) difficulty of environments, characterization of this group isolation (7,28,45,49); and (iii) past has not been extensive. This may be attributed difficulties in preservation of cultures, with t o the following factors: (i) lack of medical only continual transfer, the recently developed Contribution no. 3032 of the Woods Hole Oceanographic Institution, Woods Hole, Mass.

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This paper reports the findings of a case study in which audio feedback replaced text-based feedback in asynchronous courses. Previous research has demonstrated that participants in online courses can build effective learning communities through text-based communication alone. Similarly, it has been demonstrated that instructors for online courses can adequately project immediacy behaviors using text-based communication. However, we believed that the inclusion of an auditory element might strengthen both the sense of community and the instructor’s ability to affect more personalized communication with students. Over the course of one semester, students in this study received a mixture of asynchronous audio and text-based feedback. Our findings revealed extremely high student satisfaction with embedded asynchronous audio feedback as compared to asynchronous text only feedback. Four themes, which accounted for this preference, were culled out in an iterative, inductive analysis of interview data: 1. Audio feedback was perceived to be more effective than text-based feedback for conveying nuance; 2. Audio feedback was associated with feelings of increased involvement and enhanced learning community interactions; 3. Audio feedback was associated with increased retention of content; and 4. Audio feedback was associated with the perception that the instructor cared more about the student. Document analysis revealed that students were three times more likely to apply content for which audio commenting wasprovided in class projects than was the case for content for which text-based commenting was provided. Audio commenting was also found to significantly increase the level at which students applied such content. Implications of this case study and directions for future research are addressed in the discussion and conclusions section of this paper.

Their analysis demonstrates many instances where the c-view image quality differs from FFDM. Compared to FFDM, c-view offers a better depiction of objects of certain size and contrast, but provides poorer overall resolution and noise properties. Based on these findings, the utilization of c-view images in the clinical setting requires careful consideration, especially if considering the discontinuation of FFDM imaging. Not explicitly explored in this study is how the combination of DBT + c-view performs relative to DBT + FFDM or FFDM alone.

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Purpose: To create a database of highly realistic and anatomically variable 3D virtual breast phantoms based on dedicated breast computed tomography (bCT) data. Methods: A tissue classification and segmentation algorithm was used to create realistic and detailed 3D computational breast phantoms based on 230+ dedicated bCT datasets from normal human subjects. The breast volume was identified using a coarse three-class fuzzy C-means segmentation algorithm which accounted for and removed motion blur at the breast periphery. Noise in the bCT data was reduced through application of a postreconstruction 3D bilateral filter. A 3D adipose nonuniformity (bias field) correction was then applied followed by glandular segmentation using a 3D bias-corrected fuzzy C-means algorithm. Multiple tissue classes were defined including skin, adipose, and several fractional glandular densities. Following segmentation, a skin mask was produced which preserved the interdigitated skin, adipose, and glandular boundaries of the skin interior. Finally, surface modeling was used to produce digital phantoms with methods complementary to the XCAT suite of digital human phantoms. Results: After rejecting some datasets due to artifacts, 224 virtual breast phantoms were created which emulate the complex breast parenchyma of actual human subjects. The volume breast density (with skin) ranged from 5.5% to 66.3% with a mean value of 25.3% ± 13.2%. Breast volumes ranged from 25.0 to 2099.6 ml with a mean value of 716.3 ± 386.5 ml. Three breast phantoms were selected for imaging with digital compression (using finite element modeling) and simple ray-tracing, and the results show promise in their potential to produce realistic simulated mammograms. Conclusions: This work provides a new population of 224 breast phantoms based on in vivo bCT data for imaging research. Compared to previous studies based on only a few prototype cases, this dataset provides a rich source of new cases spanning a wide range of breast types, volumes, densities, and parenchymal patterns.

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