Estimation of elastic and viscous properties of the left ventricle based on annulus plane harmonic behavior

Assessment of left ventricular (LV) function with an emphasis on contractility has been a challenge in cardiac mechanics during the recent decades. The LV function is usually described by the LV pressurevolume (P-V) diagram. The standard P-V diagrams are easy to interpret but difficult to obtain and require invasive instrumentation for measuring the corresponding volume and pressure data. In the present study, we introduce a technique that can estimate the viscoelastic properties of the LV based on harmonic behavior of the ventricular chamber and it can be applied non-invasively as well. The estimation technique is based on modeling the actual long axis displacement of the mitral annulus plane toward the cardiac base as a linear damped oscillator with time-varying coefficients. The time-varying parameters of the model were estimated by a standard Recursive Linear Least Squares (RLLS) technique. LV stiffness at end-systole and end diastole was in the range of 61.86-136.00 dyne/g.cm and 1.25-21.02 dyne/g.cm, respectively. The only input used in this model was the long axis displacement of the annulus plane, which can also be obtained non-invasively using tissue Doppler or MR imaging

“WELL, I’VE WHISPERED ‘RACISM’ IN A POST-RACIAL WORLD”: SATIRE AND THE ABSURDITY OF “POST-RACIAL” AMERICA

The purpose of this thesis project is to look at the works of contemporary African American satirists as they confront post-racial ideology. In looking at the works of Jordan Peele, Paul Beatty, Mat Johnson, and Boots Riley, thematic threads emerge to form a portrait of dire unrest amongst those non-white identities living in an allegedly post-racial world. Before analyzing the works, I first contextualize the thesis with a brief discussion of satire as a literary genre and African American satire as a literary subgenre, as well as address the emergence of post-racial ideology during the tenure of Barack Obama as President of the United States. I then examine the ways in which Peele’s film Get Out, Beatty’s novel The Sellout, Johnson’s novel Pym, and Riley’s film Sorry to Bother You attack a variety of satirical targets that all relate to the falsehoods of post-racialism. In the first chapter, I analyze the ways in which Get Out and The Sellout address the covert nature of white supremacy in contemporary America. The second chapter covers all four artists’ satirical visions of the ways American slavery still haunts and informs our national consciousness. In the final chapter, I address the efforts of Beatty, Johnson, and Riley to foster a greater understanding of the post-racial conditions that force the act of “selling out” racial identity in service of survival. While rich in their complexities and nuances, the four artists do not offer clear answers to the problems that continue to plague non-white identity in America. However, their collective efforts to expose the lies of post-racial ideology encourage an important conversation about how goals of racial equity and acceptance might be achieved. Together, Peele, Beatty, v Johnson, and Riley indict systemic oppression and create a historical snapshot of a vitally important period in America’s continued struggles with race

Living Lawn Ornaments: Middle Class Status Anxiety in George Saunders’s “The Semplica Girl Diaries”

This paper offers an analysis of writer George Saunders’s satirical short story “The Semplica Girl Diaries.” I argue that by situating the story in the historic context of the fallout from the 2008 financial crisis, Saunders’s story not only examines middle class status anxiety, but also acts as a reflective lens for the upper class readers of the story’s original publisher: The New Yorker. I first provide a brief discussion of the economic situation faced by middle class America between 2008 and 2013. I then provide an analysis of the fears of middle class American citizens by examining the story’s narrator’s preoccupation with social status and the subsequent lack of self worth and satisfaction he finds while seeking a facade of wealth. Throughout this section, I look to sociological and economic research to provide a basis for examining the effects of class anxiety and America’s focus on class. I then move to examine the story’s format–a first person narrative written as a diary–and its effect on how readers empathize with the story’s narrator and eventually judge his decision to use human beings as a signifier of the social status. Saunders’s use of a satirical turn in the story challenges readers’ complacency with the narrator’s actions and motives, and in turn asks them to examine their own perceptions of status. I conclude with the idea that Saunders pushes the economically safe reading base that was first exposed to this story in The New Yorker to consider their own notions of class, the lengths to which their fellow citizens might go in order to breach the upper class, and their sense of superiority

Assessment of myocardial injury after reperfused infarction by T1ρ cardiovascular magnetic resonance.

BackgroundThe evolution of T1ρ and of other endogenous contrast methods (T2, T1) in the first month after reperfused myocardial infarction (MI) is uncertain. We conducted a study of reperfused MI in pigs to serially monitor T1ρ, T2 and T1 relaxation, scar size and transmurality at 1 and 4 weeks post-MI.MethodsTen Yorkshire swine underwent 90 min of occlusion of the circumflex artery and reperfusion. T1ρ, T2 and native T1 maps and late gadolinium enhanced (LGE) cardiovascular magnetic resonance (CMR) data were collected at 1 week (n = 10) and 4 weeks (n = 5). Semi-automatic FWHM (full width half maximum) thresholding was used to assess scar size and transmurality and compared to histology. Relaxation times and contrast-to-noise ratio were compared in healthy and remote myocardium at 1 and 4 weeks. Linear regression and Bland-Altman was performed to compare infarct size and transmurality.ResultsRelaxation time differences between infarcted and remote myocardial tissue were ∆T1 (infarct-remote) = 421.3 ± 108.8 (1 week) and 480.0 ± 33.2 ms (4 week), ∆T1ρ = 68.1 ± 11.6 and 74.3 ± 14.2, and ∆T2 = 51.0 ± 10.1 and 59.2 ± 11.4 ms. Contrast-to-noise ratio was CNRT1 = 7.0 ± 3.5 (1 week) and 6.9 ± 2.4 (4 week), CNRT1ρ = 12.0 ± 6.2 and 12.3 ± 3.2, and CNRT2 = 8.0 ± 3.6 and 10.3 ± 5.8. Infarct size was not significantly different for T1ρ, T1 and T2 compared to LGE (p = 0.14) and significantly decreased from 1 to 4 weeks (p < 0.01). Individual infarct size changes were ∆T1ρ = -3.8%, ∆T1 = -3.5% and ∆LGE = -2.8% from 1 - 4 weeks, but there was no observed change in infarct size for T2 or histologically.ConclusionsT1ρ was highly correlated with alterations left ventricle (LV) pathology at 1 and 4 weeks post-MI and therefore it may be a useful method endogenous contrast imaging of infarction

Patient-specific CFD simulation of intraventricular haemodynamics based on 3D ultrasound imaging

Background: The goal of this paper is to present a computational fluid dynamic (CFD) model with moving boundaries to study the intraventricular flows in a patient-specific framework. Starting from the segmentation of real-time transesophageal echocardiographic images, a CFD model including the complete left ventricle and the moving 3D mitral valve was realized. Their motion, known as a function of time from the segmented ultrasound images, was imposed as a boundary condition in an Arbitrary Lagrangian-Eulerian framework. Results: The model allowed for a realistic description of the displacement of the structures of interest and for an effective analysis of the intraventricular flows throughout the cardiac cycle. The model provides detailed intraventricular flow features, and highlights the importance of the 3D valve apparatus for the vortex dynamics and apical flow. Conclusions: The proposed method could describe the haemodynamics of the left ventricle during the cardiac cycle. The methodology might therefore be of particular importance in patient treatment planning to assess the impact of mitral valve treatment on intraventricular flow dynamics

User-initialized active contour segmentation and golden-angle real-time cardiovascular magnetic resonance enable accurate assessment of LV function in patients with sinus rhythm and arrhythmias.

BackgroundData obtained during arrhythmia is retained in real-time cardiovascular magnetic resonance (rt-CMR), but there is limited and inconsistent evidence to show that rt-CMR can accurately assess beat-to-beat variation in left ventricular (LV) function or during an arrhythmia.MethodsMulti-slice, short axis cine and real-time golden-angle radial CMR data was collected in 22 clinical patients (18 in sinus rhythm and 4 patients with arrhythmia). A user-initialized active contour segmentation (ACS) software was validated via comparison to manual segmentation on clinically accepted software. For each image in the 2D acquisitions, slice volume was calculated and global LV volumes were estimated via summation across the LV using multiple slices. Real-time imaging data was reconstructed using different image exposure times and frame rates to evaluate the effect of temporal resolution on measured function in each slice via ACS. Finally, global volumetric function of ectopic and non-ectopic beats was measured using ACS in patients with arrhythmias.ResultsACS provides global LV volume measurements that are not significantly different from manual quantification of retrospectively gated cine images in sinus rhythm patients. With an exposure time of 95.2 ms and a frame rate of > 89 frames per second, golden-angle real-time imaging accurately captures hemodynamic function over a range of patient heart rates. In four patients with frequent ectopic contractions, initial quantification of the impact of ectopic beats on hemodynamic function was demonstrated.ConclusionUser-initialized active contours and golden-angle real-time radial CMR can be used to determine time-varying LV function in patients. These methods will be very useful for the assessment of LV function in patients with frequent arrhythmias

Succession Planning in Ghana’s Nascent Technical Universities: The Case of Cape Coast Technical University

This paper investigated on succession planning in Ghana’s Technical Universities with the Cape Coast Technical University as a case. In this study, the researchers interviewed nine purposively sampled senior managerial and administrative personnel. The interview transcripts were content-analysed using the Taguette computer-aided qualitative data analysis software. The study uncovered that the CCTU has neither a succession policy nor a formal arrangement for training and mentoring personnel to fill leadership roles. Personnel interviewed demonstrated a positive perception of succession planning even though it was based on basic knowledge of the concept. Further, interviewees expressed a desire to see succession planning given a try at the CCTU.  However, they wanted such a program to be transparent, inclusive, and coherent. They also would like to see any such policy have adequate top-level backing. The challenges to a potential succession planning policy included the risk of it being abused as a tool for cronyism, the risk of people selected and sponsored under the policy leaving the organization and the risk of it only existing on paper without full implementation The authors recommend that the dominant coalition at CCTU should study feasibility of formal succession planning and formulate a unique solution that is based in local context. They also recommend that researchers expand on this study across HEIs in Ghana. Finally, the researchers recommend that it would be insightful to examine the prevalence and nature of succession planning in various Ghanaian organizations. Such research may uncover practices and leadership development philosophies that are rooted in Ghanaian culture and which may be further developed