9,976 research outputs found
Period-Color and Amplitude-Color Relations in Classical Cepheid Variables - VI. New Challenges for Pulsation Models
We present multiphase Period-Color/Amplitude-Color/Period-Luminosity
relations using OGLE III and Galactic Cepheid data and compare with state of
the art theoretical pulsation models. Using this new way to compare models and
observations, we find convincing evidence that both Period-Color and
Period-Luminosity Relations as a function of phase are dynamic and highly
nonlinear at certain pulsation phases. We extend this to a multiphase Wesenheit
function and find the same result. Hence our results cannot be due to reddening
errors. We present statistical tests and the urls of movies depicting the
Period-Color/Period Luminosity and Wesenheit relations as a function of phase
for the LMC OGLE III Cepheid data: these tests and movies clearly demonstrate
nonlinearity as a function of phase and offer a new window toward a deeper
understanding of stellar pulsation. When comparing with models, we find that
the models also predict this nonlinearity in both Period-Color and
Period-Luminosity planes. The models with (Z=0.004, Y=0.25) fare better in
mimicking the LMC Cepheid relations, particularly at longer periods, though the
models predict systematically higher amplitudes than the observations
Options for basing Dietary Reference Intakes (DRIs) on chronic disease endpoints: report from a joint US-/Canadian-sponsored working group.
Dietary Reference Intakes (DRIs) are used in Canada and the United States in planning and assessing diets of apparently healthy individuals and population groups. The approaches used to establish DRIs on the basis of classical nutrient deficiencies and/or toxicities have worked well. However, it has proved to be more challenging to base DRI values on chronic disease endpoints; deviations from the traditional framework were often required, and in some cases, DRI values were not established for intakes that affected chronic disease outcomes despite evidence that supported a relation. The increasing proportions of elderly citizens, the growing prevalence of chronic diseases, and the persistently high prevalence of overweight and obesity, which predispose to chronic disease, highlight the importance of understanding the impact of nutrition on chronic disease prevention and control. A multidisciplinary working group sponsored by the Canadian and US government DRI steering committees met from November 2014 to April 2016 to identify options for addressing key scientific challenges encountered in the use of chronic disease endpoints to establish reference values. The working group focused on 3 key questions: 1) What are the important evidentiary challenges for selecting and using chronic disease endpoints in future DRI reviews, 2) what intake-response models can future DRI committees consider when using chronic disease endpoints, and 3) what are the arguments for and against continuing to include chronic disease endpoints in future DRI reviews? This report outlines the range of options identified by the working group for answering these key questions, as well as the strengths and weaknesses of each option
About Norms and Causes
Knowing the norms of a domain is crucial, but there exist no repository of
norms. We propose a method to extract them from texts: texts generally do not
describe a norm, but rather how a state-of-affairs differs from it. Answers
concerning the cause of the state-of-affairs described often reveal the
implicit norm. We apply this idea to the domain of driving, and validate it by
designing algorithms that identify, in a text, the "basic" norms to which it
refers implicitly
Effect of the orientational relaxation on the collective motion of patterns formed by self-propelled particles
We investigate the collective behavior of self-propelled particles (SPPs)
undergoing competitive processes of pattern formation and rotational relaxation
of their self-propulsion velocities. In full accordance with previous work, we
observe transitions between different steady states of the SPPs caused by the
intricate interplay among the involved effects of pattern formation,
orientational order, and coupling between the SPP density and orientation
fields. Based on rigorous analytical and numerical calculations, we prove that
the rate of the orientational relaxation of the SPP velocity field is the main
factor determining the steady states of the SPP system. Further, we determine
the boundaries between domains in the parameter plane that delineate
qualitatively different resting and moving states. In addition, we analytically
calculate the collective velocity of the SPPs and show that it
perfectly agrees with our numerical results. We quantitatively demonstrate that
does not vanish upon approaching the transition boundary between the
moving pattern and homogeneous steady states.Comment: 3 Figure
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