Metallic Hydrogen: The Most Powerful Rocket Fuel Yet To Exist

Wigner and Huntington first predicted that pressures of order 25 GPa were required for the transition of solid molecular hydrogen to the atomic metallic phase. Later it was predicted that metallic hydrogen might be a metastable material so that it remains metallic when pressure is released. Experimental pressures achieved on hydrogen have been more than an order of magnitude higher than the predicted transition pressure and yet it remains an insulator. We discuss the applications of metastable metallic hydrogen to rocketry. Metastable metallic hydrogen would be a very light-weight, low volume, powerful rocket propellant. One of the characteristics of a propellant is its specific impulse, $I_{sp}$. Liquid (molecular) hydrogen-oxygen used in modern rockets has an Isp of $\sim460s$; metallic hydrogen has a theoretical $I_{sp}$ of 1700s! Detailed analysis shows that such a fuel would allow single-stage rockets to enter into orbit or carry economical payloads to the moon. If pure metallic hydrogen is used as a propellant, the reaction chamber temperature is calculated to be greater than 6000 K, too high for currently known rocket engine materials. By diluting metallic hydrogen with liquid hydrogen or water, the reaction temperature can be reduced, yet there is still a significant performance improvement for the diluted mixture.Physic

Cerebral Venous Thrombosis: A Clinical Overview

Cerebral venous thrombosis (CVT) is a less common cause of stroke that is an often under recognized entity in clinical practice. The goal of this chapter will be to provide clinicians with the knowledge to succinctly recognize the various presentations of CVT, emphasizing rapid diagnosis and the potential treatments necessary to produce optimal clinical outcomes. Detailed descriptions of the relevant anatomy and associated clinical syndromes will be discussed. Detailed sections regarding CVT epidemiology, pathophysiology, etiology, diagnosis and treatment will be provided. Prognosis and long-term follow-up will also be discussed. Relevant literature will be cited and clinical trials across the spectrum of CVT will be highlighted

Large Artery Occlusive Disease

Extracranial and intracranial large artery atherosclerosis is often identified as a potential etiologic cause for ischemic stroke and transient ischemic attack (TIA). Given the high prevalence of large artery atherosclerosis in the general population, optimally treating each patient to minimize future stroke risk is paramount. To optimally define treatment, as based upon the individual patient’s history, examination, and anatomical imaging findings, clinicians can compartmentalize this disease entity into four distinct clinical scenarios: 1(a) asymptomatic and 1(b) symptomatic extracranial carotid stenosis, (2) intracranial atherosclerosis, and (3) atherosclerotic vertebrobasilar disease. In this chapter, we work to provide a framework for clinicians evaluating and treating such patients

The New Vulnerability Of Higher Education

Shifts in attitudes toward the academy is a product of changes in the American political economy, especially the rapid expansion of the white-collar sector and corporate takeover, and social movements of the post-war era in which people previously without power began to assert themselves

The Journal of the Center for Interdisciplinary Teaching and Learning

IMPACT: The Journal of the Center for Interdisciplinary Teaching & Learning is a peer-reviewed, biannual online journal that publishes scholarly and creative non-fiction essays about the theory, practice and assessment of interdisciplinary education. Impact is produced by the Center for Interdisciplinary Teaching & Learning at the College of General Studies, Boston University (www.bu.edu/cgs/citl).In this issue, podcasts are looked at as a pedagogical game changer. Using the award-wining podcast Serial as their catalyst, this issue's essayists look at podcast's emerging role in higher education, how multimodal learning can help students find their voices, the podcast's place in the curriculum at a criminal justice college, and how podcasts can inspire students to reflectively assess their own writing. Our reviewers take a critical look at the podcasts Welcome to Night Vale and Revisionist History

An Exploration Perspective of Beamed Energy Propulsion

The Vision for Exploration is currently focused on flying the Space Shuttle safely to complete our Space Station obligations, retiring the Shuttle in 2010, then returning humans to the Moon and learning how to proceed to Mars and beyond. The NASA budget still includes funds for science and aeronautics but the primary focus is on human exploration. Fiscal constraints have led to pursuing exploration vehicles that use heritage hardware, particularly existing boosters and engines, with the minimum modifications necessary to satisfy mission requirements. So, pursuit of immature technologies is not currently affordable by NASA. Beamed energy is one example of an immature technology, from a human exploration perspective, that may eventually provide significant benefits for human exploration of space, but likely not in the near future. Looking to the more distant future, this paper will examine some of the criteria that must be achieved by beamed energy propulsion to eventually contribute to human exploration of the solar system. The analysis focuses on some of the implications of increasing the payload fraction of a launch vehicle, with a quick look at trans-lunar injection. As one would expect, there is potential for benefit, and there are concerns. The analysis concludes with an assessment of the Technology Readiness Level (TRL) for some beamed energy propulsion components, indicating that TRL 2 is close to being completed

Luminescence complementation technology for the identification of MYC:TRRAP inhibitors

Mechanism-based targeted therapies have exhibited remarkable success in treating otherwise untreatable or unresectable cancers. Novel targeted therapies that correct dysregulated transcriptional programs in cancer are an unmet medical need. The transcription factor MYC is the most frequently amplified gene in human cancer and is overexpressed because of mutations in an array of oncogenic signaling pathways. The fact that many cancer cells cannot survive without MYC - a phenomenon termed MYC addiction - provides a compelling case for the development of MYC-specific targeted therapies. We propose a new strategy to inhibit MYC function by disrupting its essential interaction with TRRAP using small molecules. To achieve our goal, we developed a platform using luminescence complementation for identifying small molecules as inhibitors of the MYC:TRRAP interaction. Here we present validation of this assay by measuring the disruption of TRRAP binding caused by substitutions to the invariant and essential MYC homology 2 region of MYC