Surgical management of aortic root disease in Marfan syndrome and other congenital disorders associated with aortic root aneurysms

Elective root replacement in Marfan syndrome has improved life expectancy in affected patients. Three forms of surgery are now available: total root replacement (TRR) with a valved conduit, valve sparing root replacement (VSRR) and personalised external aortic root support (PEARS) with a macroporous mesh sleeve. TRR can be performed irrespective of aortic dimensions and a mechanical replacement valve is a secure and near certain means of correcting aortic valve regurgitation but has thromboembolic and bleeding risks. VSRR offers freedom from anticoagulation and attendant risks of bleeding but reoperation for aortic regurgitation runs at 1.3% per annum. A prospective multi-institutional study has found this to be an underestimate of the true rate of valve-related adverse events. PEARS conserves the aortic root anatomy and optimises the chance of maintaining valve function but average follow-up is under 5 years and so the long-term results are yet to be determined. Patients are on average in their 30s and so the cumulative lifetime need for reoperation, and of any valve-related complications, are consequently substantial. With lowering surgical risk of prophylactic root replacement, the threshold for intervention has reduced progressively over 30 years to 4.5 cm and so an increasing number of patients who are not destined to have a dissection are now having root replacement. In evaluation of these three forms of surgery, the number needed to treat to prevent dissection and the balance of net benefit and harm in future patients must be considered

Matrix effects in ion-induced emission as observed in Ne collisions with Cu-Mg and Cu-Al alloys

Ion induced Auger electron emission is used to study the surfaces of Al, Mg, Cu - 10 at. % Al, Cu - 19.6 at. % Al, and Cu - 7.4 at. % Mg. A neon (Ne) ion beam whose energy is varied from 0.5 to 3 keV is directed at the surface. Excitation of the lighter Ne occurs by the promotion mechanism of Barat and Lichten in asymmetric collisions with Al or Mg atoms. Two principal Auger peaks are observed in the Ne spectrum: one at 22 eV and one at 25 eV. Strong matrix effects are observed in the alloys as a function of energy in which the population of the second peak is greatly enhanced relative to the first over the pure materials. For the pure material over this energy range this ratio is 1.0. For the alloys it can rise to the electronic structure of alloys and to other surface tools such as secondary ion mass spectroscopy

Thickness of the rim of an expanding lamella near the splash threshold

The evolution of the ejected liquid sheet, or lamella, created after impact of a liquid drop onto a solid surface is studied using high-speed video in order to observe the detailed time evolution of the thickness of the rim of the lamella. Since it has been suggested that splashing behavior is set at very early times after impact, we study early times up to D-0/U-0, where D-0 and U-0 are the diameter and speed of the impacting drop, respectively, for different liquid viscosities and impact speeds below the splashing threshold. Within the regime of our experiments, our results are not consistent with the idea that the lamella rim grows similar to the boundary layer thickness. Rather, we find that the rim thickness is always much larger than the boundary layer thickness, and that the rim thickness decreases with increasing impact speed. For lower impact speeds, the increase in the rim thickness is consistent with a root t response over the limited time range available, but the dependence is not simply proportional to root nu, where nu is the kinematic viscosity, and there is a strong dependence of the rim thickness on the impact speed U-0. Scaling of the rim height using a balance of inertial and surface tension forces provides some collapse of the data at lower impact speeds. We also observe an unusual plateau behavior in thickness versus time at higher impact speeds as we approach the splash threshold. (C) 2010 American Institute of Physics. [doi:10.1063/1.3313360

The KELT-South Telescope

The Kilodegree Extremely Little Telescope (KELT) project is a survey for new transiting planets around bright stars. KELT-South is a small-aperture, wide-field automated telescope located at Sutherland, South Africa. The telescope surveys a set of 26 degree by 26 degree fields around the southern sky, and targets stars in the range of 8 < V < 10 mag, searching for transits by Hot Jupiters. This paper describes the KELT-South system hardware and software and discusses the quality of the observations. We show that KELT-South is able to achieve the necessary photometric precision to detect transits of Hot Jupiters around solar-type main-sequence stars.Comment: 26 pages, 13 figure

Exercise in hispanic patients with diabetes

BACKGROUND - Obesity and physical inactivity are major risk factors in the development and progression of type 2 diabetes mellitus. Hispanic patients face barriers with language and culture in dealing with diabetes. At a Utah Community Health Center (CHC), patients needed a successful way to overcome these barriers in order to implement an exercise routine. METHODS - We prepared a Spanish language exercise DVD and distributed it free of charge to 40 overweight Hispanic patients with diabetes. Patients were given the exercise DVD as a part of a nutrition and exercise program in a 6-week study. Patients were contacted by telephone after 1 to 3 weeks to determine whether they were using the DVD. After 5-8 weeks the patients returned to clinic to be re-weighed. Patients were asked how often and how long they exercised and whether they found the Spanish language exercise DVD was helpful. RESULTS -Forty patients were evaluated. Six patients were lost to follow-up due to lost DVD, broken DVD player, or disconnected phone number. Thirty-four patients were included in the analysis. Thirteen patients showed an increase in the frequency of physical activity, 6 patients had a decrease, and 15 patients had no change in the frequency of physical activity. Fourteen patients showed an increase in the amount of time dedicated to physical activity, 2 patients showed a decrease. Eighteen patients did not change the time dedicated to physical activity and 25 patients showed a reduction in weight from baseline. CONCLUSION - Use of a Spanish language exercise DVD in a Hispanic population moderately improves frequency of physical activity, time dedicated to physical activity, and weight control

Trans Stories, Trans Voices: How the Internet Empowers Transgender Creators to Have Agency in Trans Fiction

Although many advocates believe that the increased representation of transgender people in mainstream fiction will lead to more understanding for the transgender community, many transgender scholars (Page, Richards) are critical of representation that is created without any involvement of actual transgender people. Some fear that the more radical perspectives of trans lives are being erased and replaced with a homogenous idea of the kinds of trans people who are “acceptable” (cárdenas). To avoid this homogeneity, it is important to allow for a multiplicity of trans perspectives and empower transgender people to have agency over their own narratives. The goal of this project is to highlight how trans agency in story telling can benefit trans fiction and take it beyond simply providing a “trans 101” for cisgender audiences. It will also address how the internet has benefitted trans creators by providing a platform for a variety of trans voices to share their stories. By analyzing fiction that centers on transgender experience and is created by transgender people, this thesis will explore the topics and issues addressed in trans stories and the diversity in the perspectives shown. Internet-based fiction such as webcomics and web series will be examined, as well as a trans authored anthology that was funded online. Examining these stories may show us what we are missing by relying on the current homogenous mainstream representation and open our eyes to the importance of empowering transgender people to tell their own diverse, radical stories

Time-reversal in dynamically-tuned zero-gap periodic systems

We show that short pulses propagating in zero-gap periodic systems can be reversed with 100% efficiency by using weak non-adiabatic tuning of the wave velocity at time-scales that can be much slower than the period. Unlike previous schemes, we demonstrate reversal of {\em broadband} (few cycle) pulses with simple structures. Our scheme may thus open the way to time-reversal in a variety of systems for which it was not accessible before.Comment: Accepted for publication in Phys. Rev. Letter

Upper-division Student Understanding of Coulomb's Law: Difficulties with Continuous Charge Distributions

Utilizing the integral expression of Coulomb's Law to determine the electric potential from a continuous charge distribution is a canonical exercise in Electricity and Magnetism (E&M). In this study, we use both think-aloud interviews and responses to traditional exam questions to investigate student difficulties with this topic at the upper-division level. Leveraging a theoretical framework for the use of mathematics in physics, we discuss how students activate, construct, execute and reflect on the integral form of Coulomb's Law when solving problems with continuous charge distributions. We present evidence that junior-level E&M students have difficulty mapping physical systems onto the mathematical expression for the Coulomb potential. Common challenges include difficulty expressing the difference vector in appropriate coordinates as well as determining expressions for the differential charge element and limits of integration for a specific charge distribution. We discuss possible implications of these findings for future research directions and instructional strategies.Comment: 5 pages, 1 figure, 2 tables, accepted to 2012 PERC Proceeding

ACER: A Framework on the Use of Mathematics in Upper-division Physics

At the University of Colorado Boulder, as part of our broader efforts to transform middle- and upper-division physics courses, we research students' difficulties with particular concepts, methods, and tools in classical mechanics, electromagnetism, and quantum mechanics. Unsurprisingly, a number of difficulties are related to students' use of mathematical tools (e.g., approximation methods). Previous work has documented a number of challenges that students must overcome to use mathematical tools fluently in introductory physics (e.g., mapping meaning onto mathematical symbols). We have developed a theoretical framework to facilitate connecting students' difficulties to challenges with specific mathematical and physical concepts. In this paper, we motivate the need for this framework and demonstrate its utility for both researchers and course instructors by applying it to frame results from interview data on students' use of Taylor approximations.Comment: 10 pages, 1 figures, 2 tables, accepted to the 2012 PERC Proceeding