Importance of laboratory-raised snails in helminthology with life history notes on Gyraulus parvus

http://deepblue.lib.umich.edu/bitstream/2027.42/56665/1/OP226.pd

Women community college presidents in the Midwest: experiences in leading their campuses

2011 Summer.Includes bibliographical references.This phenomenological study has examined the lived experiences of 14 women community college presidents in the Midwest. As community colleges face extraordinary challenges, leaders will be required to be innovative, creative, and responsive to the changing environments. With the impending turnover of community college presidencies by 2016 and the potential for women to assume those leadership positions, an understanding of their day-to-day experiences will prove valuable to prepare the next generation of women leaders. From the in-depth analysis of face-to-face interviews with study participants, four themes have emerged: Influences to the Presidency, Determination and Perseverance, Sense of Progress and Success, and Advice for Future Women Leaders. Broader interpretation of these themes has identified the unintentional nature of the participants' pathways to their presidencies, the impact that mentors or colleagues had on their professional development and decisions, and the self-actualization that occurred to help them realize they could be a successful president. As the presidents discussed the challenges they faced, which included leadership vacuums, gender issues, facility and financial issues, and the balance between personal and professional responsibilities, their determination and sheer will to move forward and be successful was apparent. They identified progress and success in both tangible and intangible ways. Much of the progress was dependent on their leadership skills and styles. As these presidents offered advice for future women leaders, modeling integrity, honesty, and ethics were at the forefront of all the discussions. They believed strongly that women leaders must be self-confident and utilize innate skills and strengths to create change. Their working relationship with the board and internal campus community were key factors in institutional stability and positive progress. The presidents viewed themselves as change agents for higher education. Relating the various themes to the research questions and current literature identified opportunities for further discussion. Within the four overarching themes, participants discussed the need for women leaders to have doctoral degrees, professional-development opportunities, mentors, job-shadowing, and broad-based exposure to all types of learning opportunities in order to develop needed leadership skills. Further studies are encouraged to discern how to best acquire and develop necessary leadership skills, the presidents' perceptions of preparedness for leadership, the impact of mentoring of professional development, and the correlation between leadership success and the doctoral degree area of study. Additionally, researchers could study the strengths and weaknesses of internal versus external leadership-development programs, the retention of aspiring women leaders based on leadership development programs, and the impact on institutions of the presence or absence of succession planning. Gender issues should continue to be studied as well to discern how barriers to women might be diminished

Dorsal hindbrain ablation results in rerouting of neural crest migration and changes in gene expression, but normal hyoid development

Our previous studies have shown that hindbrain neural tube cells can regulate to form neural crest cells for a limited time after neural fold removal (Scherson, T., Serbedzija, G., Fraser, S. E. and Bronner-Fraser, M. (1993). Development 188, 1049-1061; Sechrist, J., Nieto, M. A., Zamanian, R. T. and Bronner-Fraser, M. (1995). Development 121, 4103-4115). In the present study, we ablated the dorsal hindbrain at later stages to examine possible alterations in migratory behavior and/or gene expression in neural crest populations rostral and caudal to the operated region. The results were compared with those obtained by misdirecting neural crest cells via rhombomere rotation. Following surgical ablation of dorsal r5 and r6 prior to the 10 somite stage, r4 neural crest cells migrate along normal pathways toward the second branchial arch. Similarly, r7 neural crest cells migrate primarily to the fourth branchial arch. When analogous ablations are performed at the 10- 12 somite stage, however, a marked increase in the numbers of DiI/Hoxa-3-positive cells from r7 are observed within the third branchial arch. In addition, some DiI-labeled r4 cells migrate into the depleted hindbrain region and the third branchial arch. During their migration, a subset of these r4 cells up-regulate Hoxa-3, a transcript they do not normally express. Krox20 transcript levels were augmented after ablation in a population of neural crest cells migrating from r4, caudal r3 and rostral r3. Long-term survivors of bilateral ablations possess normal neural crest-derived cartilage of the hyoid complex, suggesting that misrouted r4 and r7 cells contribute to cranial derivatives appropriate for their new location. In contrast, misdirecting of the neural crest by rostrocaudal rotation of r4 through r6 results in a reduction of Hoxa-3 expression in the third branchial arch and corresponding deficits in third arch-derived structures of the hyoid apparatus. These results demonstrate that neural crest/tube progenitors in the hindbrain can compensate by altering migratory trajectories and patterns of gene expression when the adjacent neural crest is removed, but fail to compensate appropriately when the existing neural crest is misrouted by neural tube rotation

KH 15D: A Spectroscopic Binary

We present the results of a high-resolution spectroscopic monitoring program of the eclipsing pre-main-sequence star KH 15D that reveal it to be a single-line spectroscopic binary. We find that the best-fit Keplerian model has a period P = 48.38 days, which is nearly identical to the photometric period. Thus, we find the best explanation for the periodic dimming of KH 15D is that the binary motion carries the currently visible star alternately above and below the edge of an obscuring cloud. The data are consistent with the models involving an inclined circumstellar disk, as recently proposed by Winn et al. (2004) and Chiang & Murray-Clay (2004). We show that the mass ratio expected from models of PMS evolution, together with the mass constraints for the visible star, restrict the orbital eccentricity to 0.68 < e < 0.80 and the mass function to 0.125 < Fm < 0.5 Msun.Comment: 8 pages, 4 figures, 3 tables, accepted for publication in September AJ. Discussion of rotational velocity deferred to Hamilton, et al. (2004, in prep). Previously reported vsini value in error; Replaced Table 3 with new Figure 3; Added new Table 2 showing individual radial velocities w.r.t. each reference star; Fixed typo in Figure

The Magnetic Fields of Classical T Tauri Stars

We report new magnetic field measurements for 14 classical T Tauri stars (CTTSs). We combine these data with one previous field determination in order to compare our observed field strengths with the field strengths predicted by magnetospheric accretion models. We use literature data on the stellar mass, radius, rotation period, and disk accretion rate to predict the field strength that should be present on each of our stars according to these magnetospheric accretion models. We show that our measured field values do not correlate with the field strengths predicted by simple magnetospheric accretion theory. We also use our field strength measurements and literature X-ray luminosity data to test a recent relationship expressing X-ray luminosity as a function of surface magnetic flux derived from various solar feature and main sequence star measurements. We find that the T Tauri stars we have observed have weaker than expected X-ray emission by over an order of magnitude on average using this relationship. We suggest the cause for this is actually a result of the very strong fields on these stars which decreases the efficiency with which gas motions in the photosphere can tangle magnetic flux tubes in the corona.Comment: 25 pages, 5 figure