235 research outputs found
Single beat determination of intraventricular systolic dyssynchrony in paitents with atrial fibrillation and systolic dysfunction
Background:: Atrial fibrillation (AF) is the most common clinically significant cardiac arrhythmia. However, diagnosis of intraventricular dyssynchrony in patients with AF is difficult due to beat-to-beat variation. Additionally, evaluation of mechanical dyssynchrony in the traditional method is based on average of 5 to 10 beats, which is exhausting and time consuming. Single-beat evaluation of a beat with equal subsequent cardiac cycles has been proposed as an accurate method in patients with AF.
Objectives:: We proposed to evaluate intraventricular mechanical dyssynchrony by measuring time-to-peak systolic velocity between basolateral and basoseptal segments (septum to lateral wall delay) using Tissue Doppler Study (TDI) by two different methods.
Materials and Methods:: 31 patient (68 ± 10.3 years) with heart failure (EF < 35%) and AF rhythm, R-R cycle length more than 500 msec were evaluated. We found a target beat in which preceding R-R (R-R1) to pre-preceding R-R (R-R2) ratio was 1(RR1/RR2 = 1) then measured the intraventricular dyssynchrony in that cycle. Intraventricular dyssynchrony was also determined and averaged for 8 consecutive cardiac cycles. The values at RR1/RR2 = 1 were compared with the average of intraventricular dyssynchrony in eight cycles and the relationship between dyssynchrony were evaluated by paired T-test, linear Pearson correlation (r2), linear regression analysis.
Results:: The average of dyssynchrony in eight cycles showed a positive correlation with dyssynchrony in target beat RR1/RR2 = 1. Average of dyssynchrony in target beat was 46.77 msec, and average of 8 cycle was = 47.701, (P value = 0.776, Pearson linear correlation 0.769).
Conclusions:: Measurement of intraventricular dyssynchromy in basoseptal and basolateral segments in AF and heart failure patients in a single beat with RR1/RR2 = 1 , were very similar to the average value of eight cardiac cycle
Helicity and spin conservation in Maxwell theory and Linearized Gravity
A duality symmetric formulation of linearized gravity has been introduced by Barnett and used to show the conservation of helicity. However, the relation between helicity and spin as well as the separate conservation of the spin and orbital parts of angular momentum, which is known to hold in Maxwell theory, was not considered. These conservation laws are known to follow from the conservation of the so-called helicity array, an analog of the zilch tensor, which includes helicity, spin, and spin-flux or infra-zilch. In the present paper we prove the conservation of spin and orbital angular momentum for linearized gravity on Minkowski space, and construct the analog of the helicity array for linearized gravity
Of Gods and Man: The Biocognitive Turn in Religious Studies
This thesis surveys and analyzes the biocognitive turn in Religious Studies over the last decade, which is characterized by a rise in cognitive and evolutionary accounts of religious beliefs and practices. Using Michel Foucault's archaeological method, I analyze three key discourses--evolutionary and cognitive explanations of religion, sui generis defenses of religion as irreducible by science, and inaugural projects for streamlining Religious Studies--with attention to how they mobilize a set of shared intellectual categories and presuppositions. Central to all of these biocognitive discourses, I argue, is Foucault's analytic of finitude, or the epistemological framing of Man as both an object of knowledge and a subject who knows.Master of Art
Helicity, Spin, and Infra-zilch of Light: a Lorentz Covariant Formulation
The spin part of angular momentum of the electromagnetic field is known since the 1990's to be a separately conserved quantity. Cameron et al. introduced the helicity array, a non-covariant analog of Lipkin's zilch tensor, which expresses the hierarchy of conservation laws including helicity, spin, as well as the spin-flux or infra-zilch. In this paper, a novel conserved Lorentz covariant tensor, termed the helicity tensor, is introduced. The conservation laws arising from the helicity array can be obtained from the helicity tensor. The Lorentz covariance of the helicity tensor is in contrast to previous formulations of the helicity hierarchy of conservation laws, which required the non-Lorentz covariant transverse gauge. The helicity tensor is shown to arise as a Noether current for a variational symmetry of a duality-symmetric Lagrangian for Maxwell theory
Energy, exergy, and economic evaluation of integrated waste incineration facility with a thermal power plant
Increased waste production and poor waste management have created severe negative environmental impacts. Waste incineration is a way to produce energy and decreases environmental impacts; however, this technique cannot be considered independently as a source of power generation because of its low performance. This study aims to evaluate the integration of a waste incineration system with a natural gas-fired power plant in terms of energy, exergy, and economic points. As a result of the proposed configurations, in addition to promoting efficiency and net power production, some equipment is removed from power plants. Efforts are made to increase the accuracy of simulation results by paying attention to the combustion process in boilers and predicting the actual working condition of feed water heaters. Results showed that the hybrid scheme improves electricity generation by up to 2.87 MW and boosts energy, and exergy efficiency by up to 0.32%, and 0.3%, respectively
Religion Made Flesh: Modernity, Ideology, and the New Sciences of the Brain
Since the turn of the twenty-first century, the human brain has become a unique and popular explanatory object. Drawing on concepts from the recent boom of the neurosciences, scholars and popular writers have sought to explain various cultural phenomena—including gender, politics, and religion—as the products of underlying cognitive processes. The human brain represents a unique rhetorical device because it serves as a bridge, in such explanations, between human culture and the seemingly objective laws of nature. This dissertation analyzes brain-based explanations of religion, with a focus on the recent research program known as the cognitive science of religion. It frames the cognitive science of religion as the most recent in a series of historical attempts to essentialize religion, or explain the fundamental truth of religion by identifying a single element that transcends the local specificities of language, culture, and history. Through a series of close readings, this dissertation demonstrates how cognitive theories of religion posit a cognitive fundament where the absolute truth of religion might reside. The central argument of the dissertation is that it is categorically impossible to essentialize religion as an inherently cognitive phenomenon. This dissertation responds to contemporary reformers of religious studies including Ann Taves, Edward Slingerland, and Robert McCauley. Drawing on concepts including neuroplasticity, morphospace, and dynamic systems theory, it argues for a pluralistic epistemological approach to the study of religion.Doctor of Philosoph
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