Sexual Differentiation of the Surge Mode of Gonadotropin Secretion: Prenatal Androgens Abolish the Gonadotropin‐Releasing Hormone Surge in the Sheep

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106142/1/j.1365-2826.1996.tb00698.x.pd

Synthesis of C(3) Benzofuran-Derived Bisaryl Quaternary Centers: Approaches to Diazonamide A

Two complementary strategies for the synthesis of the diazonamide A bisaryl quaternary center are described. The first strategy relies upon an extremely facile tandem cyclopropanation/ring-opening sequence, which has proven amenable to chiral catalysis to provide enantioenriched material. The second strategy relies upon a more concise alkylation route ideal for material advancement

Entrainment of the Melatonin Rhythms in Early Postnatal Lambs and Their Mothers

Although the developing sheep can produce an appropriately timed melatonin rhythm as early as 1 week after birth, it is not known whether the lamb is able to adjust its melatonin rhythm to a change in daylength. The ability of the young lamb to entrain its pattern of melatonin secretion to a new photoperiod was determined in the present study. Eight female lambs and their mothers were raised in long days (LD 16:8) beginning 2 weeks post partum. At 7 weeks of age, the time of lights-off was advanced 8 hr, the short-day photoperiod then being LD 8:16; the time of lights-on remained unchanged. Concentrations of melatonin were measured in blood samples collected hourly on days - 1, 0, 2, 4, 6, and 13 relative to the light change. On day 0, all mothers and daughters had advanced the onset of melatonin secretion by at least 1 hr, and by day 13, 12 of 16 had completely entrained to the new photoperiod. The rate of entrainment among individuals varied; the mean rate for lambs and mothers did not differ. This study provides evidence that the melatonin-rhythm-generating system matures shortly after birth.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68290/2/10.1177_074873048900400405.pd

Three femoral stem designs without corrosion: A review of 2095 stems

© 2020 Naudie et al. Introduction: Corrosion at the head–neck interface of modular components in total hip arthroplasty (THA) has been reported as a cause of failure of modern total hip replacement implants. While this method of failure has been well described, it remains poorly understood. The purpose of this study is to review the three most commonly used uncemented femoral stems at our institution over the last fifteen years and to correlate any established risk factors with rates of revision, particularly corrosion. Methods: We reviewed 2095 patients from March 2000 to September 2015 who underwent total hip arthroplasty with one of three uncemented femoral stem designs. All stems were made of a Ti6Al4V alloy with a 12/14 taper design. We included only those stems coupled with a CoCr head and a highly crosslinked polyethylene liner. We evaluated age, gender, body mass index (BMI), femoral head size, head length, neck angle and offset and correlated these to the incidence of all cause revision, as well as revision excluding infection. Results: There were no recognized corrosion-related revisions identified. There was no association between age, BMI, gender, head length, neck angle and offset to all cause revision or revision with infection excluded (p\u3e0.05). Femoral head size less than 32mm was associated with higher all cause revision rates (OR 4.60 (95% CI 1.8, 11.8)) and when excluding infection as a reason for revision (OR 4.94 (95% CI 1.7, 14.41)). Conclusion: Over the last fifteen years, we have not identified any cases of corrosion with the three most commonly used femoral stems used at out institution. While we acknowledge that no femoral stem is immune to corrosion, certain femoral stem designs may be uniquely resistant to this mode of failure. Level of Evidence: III

Causes of Uprooting and Breakage of Specimen Giant Sequoia Trees

A study of the causes of uprooting and stem failure in old-growth giant sequoia (Sequoia gigantea [Lindl.] Decne) indicated many factors, depending upon the type of failure (by root, stem, or earth). Advanced decay and fire scars were the most frequently associated with failure. In 21 of 33 study trees, one-third or more of the roots were judged too decayed to provide support. Twenty-seven study trees possessed basal fire scars, and 26 fell toward the scarred side. Nine Basidiomycetes, including Fomes annosus, Poria albipellucida, Poria incrassata, and Armillaria mellea, were associated with decayed wood. Carpenter ants were found in or adjacent to the failure zone of nearly half of the study trees. Physical disturbances (e.g., roads, trails, streams) were associated with 22 tree failures, but their role in initiating requires further investigating

Type II Supernovae as Probes of Cosmology

- Constraining the cosmological parameters and understanding Dark Energy have tremendous implications for the nature of the Universe and its physical laws. - The pervasive limit of systematic uncertainties reached by cosmography based on Cepheids and Type Ia supernovae (SNe Ia) warrants a search for complementary approaches. - Type II SNe have been shown to offer such a path. Their distances can be well constrained by luminosity-based or geometric methods. Competing, complementary, and concerted efforts are underway, to explore and exploit those objects that are extremely well matched to next generation facilities. Spectroscopic follow-up will be enabled by space- based and 20-40 meter class telescopes. - Some systematic uncertainties of Type II SNe, such as reddening by dust and metallicity effects, are bound to be different from those of SNe Ia. Their stellar progenitors are known, promising better leverage on cosmic evolution. In addition, their rate - which closely tracks the ongoing star formation rate - is expected to rise significantly with look- back time, ensuring an adequate supply of distant examples. - These data will competitively constrain the dark energy equation of state, allow the determination of the Hubble constant to 5%, and promote our understanding of the processes involved in the last dramatic phases of massive stellar evolution.Comment: Science white paper, submitted to the Decadal committee Astro201