نتایج جستجو برای: attenuation relationships

تعداد نتایج: 275770  

2014
Jing Peng Ashish Agarwal Kartik Hosanagar Raghuram Iyengar

Social advertising holds the potential to reshape the traditional advertising industry. Understanding what leads to effective social contagion at the dyadic level lies at the core of cost-effective social advertising strategies. This paper is the first attempt to comprehensively study the effect of dyadic network relationship on social contagion in directed networks. This paper reveals several ...

Journal: :Journal of adolescence 2015
Agueda Parra Alfredo Oliva Inmaculada Sánchez-Queija

The main objective of this study was to learn whether emotional autonomy is truly part of a developmental stage for Spanish adolescents and young adults or if it is an indicator of difficult family relationships. Using a longitudinal design, a sample of ninety young people was followed for ten years, from their initial adolescence until their first years of adulthood. At four observation points...

Abbas Takavar Davood Beiki, Mehdi Sohrabi Mohammad Eftekhari, Mohsen Saghari N Mostaghim

SPECT detects γ-rays from administered radiopharmaceutical within the patient body. γ-rays pass through different tissues before reaching detectors and are attenuated. Attenuation can cause artifacts; therefore different methods are used to minimize attenuation effects. In our study efficacy of Chang method was evaluated for attenuation purpose, using a custom made heart phantom. Due to d...

Maryam Naji Mehdi Momennezhad, Mohsen Hajizadeh Seyed Rasoul Zakavi,

  Introduction: Attenuation correction is a useful process for improving myocardial perfusion SPECT and is dependent on activity and distribution of attenuation coefficients in the body (attenuation map). Attenuation artifacts are a common problem in myocardial perfusion SPECT. The aim of this study was to compare the effect of attenuation correction using different a...

Journal: :Synthese 2009
John Matthewson Michael Weisberg

Despite their best efforts, scientists may be unable to construct models that simultaneously exemplify every theoretical virtue. One explanation for this is the existence of tradeoffs: relationships of attenuation that constrain the extent to which models can have such desirable qualities. In this paper, we characterize three types of tradeoffs theorists may confront. These characterizations ar...

1998
A. Selamet V. Easwaran J. M. Novak R. A. Kach

Acoustic wave propagation and attenuation in catalytic converters are investigated in the present study. The relationships for wave propagation in a catalytic monolith are derived first and then coupled to the wave propagation in tapered ducts which are commonly placed at either end of the monolith. Analytical and finite element approaches are used to solve the resulting coupled system of equat...

Journal: :Computers & Mathematics with Applications 2013
Sverre Holm Sven Peter Näsholm Fabrice Prieur Ralph Sinkus

It is argued that fractional acoustic wave equations come in two kinds. The first kind is constructed ad hoc to have loss operators that fit power law measurements. The second kind is more fundamental as they in addition are based on underlying physical equations. Here that means constitutive equations. These equations are the fractional Kelvin‐Voigt and the more general fractional Zener stress...

2011
Paul Withers

[1] We investigate the ionospheric conditions required to explain Mars Express Mars Advanced Radar for Subsurface and Ionosphere Sounding topside radar sounder observations of ionospheric attenuation in excess of 13 dB at 5 MHz during solar energetic particle events. We develop theoretical expressions for the attenuation caused by a layer of ionospheric plasma in cases of high, intermediate, an...

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