3,988 research outputs found
Pion Photoproduction Amplitude Relations in the 1/N_c Expansion
We derive expressions for pion photoproduction amplitudes in the 1/N_c
expansion of QCD, and obtain linear relations directly from this expansion that
relate electromagnetic multipole amplitudes at all energies. The leading-order
relations in 1/N_c compare favorably with available data, while the
next-to-leading order relations seem to provide only a small improvement.
However, when resonance parameters are compared directly, the agreement at
O(1/N_c) or O(1/N_c^2) is impressive.Comment: 19 pages, ReVTeX, 50 eps files combine into 5 compound figure
Time Averaged Quantum Dynamics and the Validity of the Effective Hamiltonian Model
We develop a technique for finding the dynamical evolution in time of an
averaged density matrix. The result is an equation of evolution that includes
an Effective Hamiltonian, as well as decoherence terms in Lindblad form.
Applying the general equation to harmonic Hamiltonians, we confirm a previous
formula for the Effective Hamiltonian together with a new decoherence term
which should in general be included, and whose vanishing provides the criteria
for validity of the Effective Hamiltonian approach. Finally, we apply the
theory to examples of the AC Stark Shift and Three- Level Raman Transitions,
recovering a new decoherence effect in the latter.Comment: 7 pages, 2 figure
The State of the Parties 2018 (Eight Edition)
The State of the Parties 2018 brings together leading scholars of parties, elections, and interest groups to provide an indispensable overview of American political parties today. The 2016 presidential election was extraordinary, especially the unexpected nomination and election of Donald Trump to the White House. What role did political parties play in these events? How did the party organizations fare? What are the implications for the future? Scholars and practitioners from throughout the United States explore the current state of American party organizations, constituencies and resources at the national, state and local level.https://ideaexchange.uakron.edu/state_of_the_parties8/1000/thumbnail.jp
The State of the Parties (Seventh Edition)
Continuing a three-decade tradition, The State of the Parties 7th edition brings together leading experts to evaluate change and continuity in American electoral politics. Political parties in America have never been more contentious and divided than they are right now. Even splits within the parties themselves have the power to elevate relatively unknown candidates to power and topple established incumbents. With sections devoted to polarization and the electorate, polarization and political elites, tea party politics, super PACS, and partisan resources and partisan activities, the contributors survey the American political landscape. They pay special attention to polarization between and within the parties in the aftermath of the 2012 election, demographic changes to America\u27s political parties, the effects of new media and campaign finance laws on national and local electoral results, the Tea Party\u27s rise and, as always, the implications of all these factors on future policymaking and electoral prospects. The State of the Parties 7th edition offers an indispensable guide to American politics for scholars, students, and practitioners.https://ideaexchange.uakron.edu/state_of_the_parties7/1000/thumbnail.jp
Fungicidal preparations from Inula viscose
Inula viscosa is a perennial plant native to the Mediterranean Basin. Extracts made from the shoots of this plant exhibited a strong fungicidal activity in vitro and in vivo. TLC analyses revealed at least 7 fungicidal compounds. Most are lipophilic. When such extracts were sprayed on the leaf surface of crop plants they effectively controlled downy mildew in grape, cucumber and tabacco; late blight in potato and tomato; gray mold in cucumber and tomato; and, powdery mildew in cucurbits and cereals. Field experiments conducted with grape vine resulted in effective control of Plasmopara viticola. The data suggest that Inula viscosa is a useful source of herbal fungicidal preparations for agricultural use
Chiral Corrections to Lattice Calculations of Charge Radii
Logarithmic divergences in pion and proton charge radii associated with
chiral loops are investigated to assess systematic uncertainties in current
lattice determinations of charge radii. The chiral corrections offer a possible
solution to the long standing problem of why present lattice calculations yield
proton and pion radii which are similar in size.Comment: PostScript file only. Ten pages. Figures included. U. of MD Preprint
#92-19
Keeping Secrets: Multi-objective Genetic Improvement for Detecting and Reducing Information Leakage
Information leaks in software can unintentionally reveal private
data, yet they are hard to detect and fix. Although several methods
have been proposed to detect leakage, such as static verificationbased approaches, they require specialist knowledge, and are timeconsuming. Recently, HyperGI introduced a dynamic, hypertestbased approach that detects and produces potential fixes for information leakage. Its fitness function tries to balance information
leakage and program correctness, but as the authors of that work
point out, there may be a tradeoff between keeping program semantics and reducing information leakage.
In this work we ask if it is possible to automatically detect and
repair information leakage in more realistic programs without requiring specialist knowledge. Our approach, called LeakReducer explicitly encodes the tradeoff between program correctness and
information leakage as a multi-objective optimisation problem. We
apply LeakReducer to a set of leaky programs including the well
known Heartbleed bug. It is comparable with HyperGI on their toy
applications. In addition, we demonstrate it can find and reduce
leakage in real applications and we see diverse solutions on our
Pareto front. Upon investigation we find that having a Pareto front
helps with some types of information leakage, but not all
Environmental Correlates of Nesting Success in Red-Shouldered Hawks
We evaluated the influence of weather on reproduction of the Red-shouldered Hawk (Buteo lineatus) in an agricultural landscape in south-central Florida where we found relatively high densities of successfully nesting hawks. We used a generalized linear modeling approach within an information-theoretic framework to examine the influence of total rainfall, rainfall frequency, and temperature on the timing of nesting, nesting success, and productivity of hawks during 1995-2000. The best models indicated an influence of rainfall frequency and laying period on hawk reproduction. During years with less frequent rainfall in the summer and fall months prior to the beginning of the breeding season, fewer pairs attempted to nest, and hawks nested later and had smaller clutch sizes and lower productivity. Hawks that nested later in the breeding season had lower hatching success and lower overall nest success. Although Red-shouldered Hawks are generally reported to inhabit forested landscapes throughout their range, a common feature seems to be a dependence on wetlands and riparian habitat for foraging. We propose that the proportion of wetlands throughout the landscape is a unique aspect of south-central Florida that may allow for persistence of unusually high numbers of hawks
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