1,901 research outputs found
On the Cosmic Nuclear Cycle and the Similarity of Nuclei and Stars
Repulsive interactions between neutrons in compact stellar cores cause
luminosity and a steady outflow of hydrogen from stellar surfaces. Neutron
repulsion in more massive compact objects made by gravitational collapse
produces violent, energetic, cosmological events (quasars, gamma ray bursts,
and active galactic centers) that had been attributed to black holes before
neutron repulsion was recognized. Rather than evolving in one direction by
fusion, nuclear matter on the cosmological scale cycles between fusion,
gravitational collapse, and dissociation (including neutron-emission). This
cycle involves neither the production of matter in an initial Big Bang nor the
disappearance of matter into black holes. The similarity Bohr noted between
atomic and planetary structures extends to a similarity between nuclear and
stellar structures.Comment: 21 pages, 4 figure
Observational confirmation of the Sun's CNO cycle
Gamma rays from a solar flare in Active Region 10039 on 23 July 2002 with the
RHESSI spacecraft spectrometer indicate that the CNO cycle occurs at the solar
surface, in electrical discharges along closed magnetic loops. At the two feet
of the loop, H ions are accelerated to energy levels that surpass Coulomb
barriers for the C-12[H-1, gamma]N-13 and N-14[H-1, gamma]O-15 reactions. First
x-rays appear along the discharge path. Next annihilation of positrons from
N-13 and O-15 [half-life = 10 m and 2 m] produce bright spots of 0.511 MeV
gammas at the loop feet. As C-13 increases from positron decay of N-13, the
C-13[He-4, n]O-16 reaction produces neutrons and then the 2.2 MeV emission line
appears from n-capture on H-1. These results suggest that the CNO cycle changed
the N-15/N-14 ratio in the solar wind and at the solar surface over geologic
time, and this ratio may contain an important historical record of climate
changes related to sunspot activity.Comment: 9 pages, 21 references, 2 figures show x-rays and gamma-rays from
nuclear reactions in a solar-flare-induced electrical discharge. Replaced to
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Improving WebIDE through Delightful Design and Gamification
WebIDE is a web-based online learning environment. WebIDE has been used
successfully to teach CS0 and CS1 students Java and C concepts and software
engineering best practices, specically Test Driven Development. Previous Web-
IDE development has concentrated on developing functionality. The main goal
of this eort is to improve two non-functional aspects of WebIDE. The rst is to
design a more delightful user interface. The second is to add a scoring mecha-
nism that encourages students to develop best practices. The scoring mechanism
rewards students who answer the question correctly on the rst attempt, dis-
couraging them from spamming the answer button. Our objective is to motivate
the students to think before answering. The innovations are evaluated through
a semi-controlled experiment that was conducted during the Fall quarter of 2012
at Cal Poly
Functionalization of pyridines and other azines via phosphorus ligand-coupling reactions
2019 Fall.Includes bibliographical references.Nitrogen heterocycles are ubiquitous in pharmaceutical compounds with pyridine being one of the most frequently occurring examples. The discovery and development of new drugs rely heavily on our ability to modify these commonly occurring structures. The functionalization of pyridine has a long history but despite this, there remain some deficiencies in this area of synthesis. Reactions which expand upon the known methodologies are of tremendous value to medicinal chemists who frequently work with pyridines and similar azines. Chapter one will cover the relevance of pyridines in pharmaceuticals and will explain how structural features contribute to their presence in drugs. Conventional and newer methods to functionalize pyridine are also addressed. Chapter two will describe the work of the McNally lab in the development of heterocyclic phosphonium salts as reagents to selectively functionalize pyridines. An application of these salts is as precursors to form C−O bonds from alkoxide nucleophiles. Chapter three presents the development of a strategy to construct bis-heterobiaryls using phosphorus ligand-coupling. This method offers an alternative to the widely used metal-catalyzed approaches which often struggle in the synthesis of bis-heterobiaryls. Lastly, chapter four will expand upon this work showing a new approach to prepare bis-heterobiaryls using heteroaryl halides. This route enables easy access to 2,2'-bipyridines which are difficult to synthesize using conventional methods
Literacy, Poverty, and Brain Development: Toward a New, Place-Based Educational Intervention
This paper provides an overview of emerging research focused on how living in an area of concentrated poverty can impact brain development and explores some possible applications of this research to education policy. One of the key findings is that state and federal policy-makers may need to adopt programs that integrate educational policy with housing and planning policy in order to protect and fulfill each child\u27s educational rights. In order to impress upon readers the scale of the nation\u27s current educational failures and the need for a significant change in policy, this paper first addresses adult illiteracy in the United States. After defining functional illiteracy according to metrics derived from the National Adult Literacy Survey, this paper then explores the various ways in which high rates of functional illiteracy negatively impact our society. The negative effects of living in an area of concentrated poverty, which correlates with functional illiteracy, and the difficulty inherent in escaping such areas of concentrated poverty are also briefly examined. The paper then proceeds to discuss the evolution of educational rights, and how federal and state courts have interpreted state obligations to provide a fair, equal, and meaningful opportunity to a sound basic education. The paper also examines the effectiveness of various remedies instituted as a result of successful education litigation. This discussion aims to establish not only the existence of educational rights, but also the inadequacy of previous efforts to implement and enforce such rights. The key problem identified in the paper is that previous approaches to effectuate educational rights, including court-ordered remedies, have failed to account for circumstantial factors relating to the socio-economic conditions within particular school districts. Finally, the paper provides an overview of emerging neuroscience research related to cognitive development and socioeconomic status, which illustrates how the circumstances in which a child is raised can significantly inhibit that child\u27s educational opportunities. While the field of neuroscience has only just begun to investigate the effects of socioeconomic status, including both family and community wealth, on brain development and function, preliminary studies indicate a correlation between socioeconomic status and some aspects of brain development which may have an impact on student performance in typical school settings
An evaluation of interactive test-driven labs with webIDE in CS0
WebIDE is a framework that enables instructors to develop and deliver online lab content with interactive feedback. The ability to create lock-step labs enables the instructor to guide students through learning experiences, demonstrating mastery as they proceed. Feedback is provided through automated evaluators that vary from simple regular expression evaluation to syntactic parsers to applications that compile and run programs and unit tests. This paper describes WebIDE and its use in a CS0 course that taught introductory Java and Android programming using a test-driven learning approach. We report results from a controlled experiment that compared the use of dynamic WebIDE labs with more traditional static programming labs. Despite weaker performance on pre-study assessments, students who used WebIDE performed two to twelve percent better on all assessments than the students who used traditional labs. In addition, WebIDE students were consistently more positive about their experience in CS0
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