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The one-cent magenta : inside the quest to own the most valuable stamp in the world
\"When it was issued in 1856, it cost a penny. In 2014, this tiny square of faded red paper sold at Sotheby's for nearly $9.5 million, the largest amount ever paid for a postage stamp at auction. Through the stories of the eccentric characters who have bought, owned, and sold the one-cent magenta in the years in between, James Barron delivers a fascinating tale of global history and immense wealth, and of the human desire to collect\"-- Provided by publisher.
Book
First results of a magnetic survey of classical Cepheids
We report recent ESPaDOnS and HARPSpol spectropolarimetric observations from our ongoing magnetic survey of the brightest twenty-five classical Cepheids. Stokes V magnetic signatures are detected in eight of fifteen targets observed to date. The Stokes V profiles show a diversity of morphologies with weak associated longitudinal field measurements of order 1 G. Many of the Stokes V profiles are difficult to interpret in the context of the normal Zeeman effect. They consist of approximately unipolar single or double lobe(s) of positive or negative circular polarization. We hypothesize that these unusual signatures are due to the Zeeman effect modified by atmospheric velocity or magnetic field gradients. In contrast, the Stokes V profiles of Polaris and MY Pup appear qualitatively similar to the complex magnetic signatures of non-pulsating cool supergiants, possibly due to the low pulsation amplitudes of these two stars.
Journal Article
Analysis of potential factors allowing coexistence in a sexual/asexual minnow complex
The northern redbelly dace (Chrosomus eos) and the finescale dace (C. neogaeus) have hybridized to produce an all-female, asexual hybrid (C. eos-neogaeus) that reproduces by sperm-limited parthenogenesis (gynogenesis). However, in this system, gynogenesis is not 100 % efficient; triploid females are occasionally formed which reproduce as sexuals, producing nuclear males and females of the paternal species (generally C. eos). Thus, the asexual lineage continually produces occasional males that can serve as a sperm source. Because (almost) all hybrid offspring are females, the hybrid population has the potential to grow more quickly and even outcompete the sexuals, thus eliminating their own sperm source. The current research uses behavioral testing, ovarian analyses, and modeling to examine three hypotheses for the maintenance of the sexual/asexual complex: male discrimination against hybrid females, fecundity differences between sexual and asexual females, and production of nuclear male sexuals from the asexual lineage. Results suggest that males do not discriminate against asexual females, and that both sexual and asexual females have similar fecundities, eliminating these hypotheses as potential coexistence mechanisms. However, computer simulations of population growth support the hypothesis that occasional triploidy within the hybrid population supplies enough breeding males to maintain the sexual/asexual complex.
Journal Article
Is it time to change? Portable echocardiography demonstrates high prevalence of abnormalities in self-presenting members of a rural community in Kyrgyzstan
Objectives
Cardiovascular disease accounts for 42% of male and 51% of female mortality within Europe. Kyrgyzstan, population of almost 6 million, has amongst the highest rates within Europe, second only to Uzbekistan for female cardiovascular disease mortality (588 per 100,000). We attempted to identify established cardiovascular disease prevalence within a rural community in Kyrgyzstan using portable echocardiography.
Design
Free open access echocardiography (VIVID-I, GE, USA) was offered to all adults in Batken district. Routine echocardiographic views were obtained and analysis performed using EchoPac Clinical Workstation (GE, USA). Mild valvular regurgitation, mild LV hypertrophy, patent foramen ovales and mild atrial enlargement were considered mild abnormalities; compensated ischaemic or valvular heart disease – moderate abnormalities, and decompensated congenital, ischaemic or valvular disease – severe abnormalities.
Results
One hundred and twenty five adults (48 male, 77 female), mean age 53 ± 16 years, underwent echocardiography. Only 16% of participants had no significant abnormality, 46% had mild disease, 25% moderate, compensated disease and 13% had severe disease. Nine percent had congenital heart disease including one tetralogy of Fallot and one Ebstein’s anomaly. Average LV function was normal, however, 19 participants had EF < 50%. Forty percent of participants had a new diagnosis warranting formal follow-up, 12% a new diagnosis of heart failure.
Conclusion
Using portable echocardiography, we identify a higher than reported prevalence of cardiovascular disease in rural Kyrgyzstan. Absence of portable tools and specialists for early diagnosis might lead to presentation in an advanced stage of disease when little can be done to improve mortality. Embracing remote access diagnostics is essential for disease identification within rural communities.
Journal Article
Midterm and First-Exam Grades Predict Final Grades in Biology Courses
Students routinely ignore negative feedback regarding their performances early in college science courses. In this study we analyzed the extent to which two standard forms of feedback, midterm and first-exam grades, correlated with final grades in several biology courses. The courses ranged from an introductory course for nonmajors to upper division, majors-only courses. Data were collected at two different types of institutions: a small liberal arts college and a regional state university. In all cases analyzed, midterm and firstexam grades strongly predicted final grades: Grades often did not change throughout the semester, changes that did occur were minimal, and early grades and final grades were strongly correlated. Midterm and final grades were also strongly correlated in a variety of other academic disciplines at the liberal arts college, including the humanities, the social sciences, and the fine arts. These data may help instructors more clearly communicate to students the importance of doing well early in a course and setting good academic habits early in the semester.
Journal Article
A Systematic Study of the TESS Photometry of the Magnetic O-Type Stars
Large spectropolarimetric surveys have revealed that a relatively rare sub-population (<10%) of massive O-type stars possess detectable photospheric magnetic fields. There are many open questions surrounding the magnetic fields of O-type stars, including their origin, impact on stellar evolutionary paths and role in observed O star spectral and photometric variability. However, the small number of known magnetic O stars has significantly hindered our understanding of their global properties. Only eleven Galactic magnetic O stars have been confirmed, and another six magnetic candidates have been identified in the Magellanic Clouds. Recent high-precision photometry obtained by the Transiting Exoplanet Survey Satellite (TESS) is providing significant advancements to the fields of massive star magnetism and asteroseismology. Diverse variability has been seen in the TESS light curves of O-type stars, offering an unprecedented opportunity to study their physical properties. We have performed a systematic analysis of the TESS light curves of the known magnetic O stars and extra-galactic magnetic candidates to characterize their variability and search for signatures of rotational modulation due to co-rotating magnetospheres. We perform custom light curve extractions in order to investigate systematics related to the detrending process and search for contaminating signals from blended sources. We detect a variety of signals in the TESS light curves of the Galactic magnetic O stars, including rotational modulation, stochastic low-frequencies and possible coherent low-frequency pulsations. We detect rotational modulation in two of the extra-Galactic magnetic candidates. These results have important implications for understanding the origins of O star photometric variability and will help inform future searches for new magnetic O star candidates using TESS photometry.
Dissertation
Reproductive Traits in the Northern Scorpion (Paruroctonus boreus)
Despite its large geographic range, little is known about reproductive traits in the northern scorpion (Paruroctonus boreus). We analyzed reproductive traits for 36 females from a population near Billings, Montana. All data were collected within a single year. Litter size, offspring mass, total litter mass (TLM), and relative litter mass (RLM) were within the ranges of values reported for other species in the Vaejovidae. Female size (length or mass) was not correlated with any reproductive trait. Litter size and offspring mass were each positively correlated with RLM, suggesting that females investing relatively larger amounts of energy in reproduction increase both size and number of offspring. Finally, the within-litter coefficient of variation in offspring mass was negatively correlated with RLM, TLM, and mean offspring mass, suggesting that females investing more energy in reproduction produce more-uniformly sized offspring, an observation that appears common in scorpions.
Journal Article