Reverse remodeling and the mechanism of mitral regurgitation improvement in patients with dilated cardiomyopathy

Background: Functional mitral regurgitation (MR) is a common finding in dilated cardiomyopathy. Left ventricular (LV) reverse remodeling with LV size reduction and improvement in LV function is a well recognized phenomenon. We aimed to evaluate the impact of LV remodeling on the mechanism leading to functional MR. Methods: Among 188 patients with non-ischemic dilated cardiomyopathy, 10 patients significantly improved their LV function, reduced LV size and MR severity during follow-up (RRMR). A comparison was made between their baseline and follow-up echocardiographic examinations and to a matched-control group of patients who did not improve (no RRMR). LV and left atrium (LA) dimensions and volumes, LV mass (LVM), LV ejection fraction (LVEF) (Simpsons), sphericity index (SI), mitral valve tenting area (TA) coaptation distance (CD), effective regurgitant orifice (ERO), and regurgitant volume were calculated. Multivariable analysis was performed in order to evaluate which echocardiographic parameters related to MR improvement in reverse remodeling. Results: LV and LA dimensions and volumes, LVM, SI, TA, CD, ERO and right ventricle, in the RRMR group significantly decreased at follow-up (p < 0.04 for all). When compared to no RRMR, despite a similar ERO (0.2 ± 0.05 vs. 0.2 ± 0.08, p = 0.13) and a larger regurgitant volume (38 ± 9 vs. 29 ± 8 mL, p = 0.05) and despite similar clinical characteristics and medical treatment we found significantly higher LVEF, smaller LV dimensions and volumes, smaller LVM and SI in the RRMR group (p < 0.05 for all). On multivariable analysis the SI was the sole predictor of RRMR (p = 0.04, OR = 0.76, CI 0.58–0.99). Conclusions: Reverse remodeling characterized by improvement in LV function, reduction in LV size and an associated reduction in MR severity is related to LV SI at baseline.

Pseudo-discordance mimicking low-flow low-gradient aortic stenosis in transcatheter aortic valve replacement patients with severe symptomatic aortic stenosis

Background: While the combination of a small aortic valve area (AVA) and low mean gradient is frequently labeled ‘low-flow low-gradient aortic stenosis (AS)’, there are two potential causes for this finding: underestimation of mean gradient and underestimation of AVA. Methods: In order to investigate the prevalence and causes of discordant echocardiographic findings in symptomatic patients with AS and normal left ventricular (LV) function, we evaluated 72 symptomatic patients with AS and normal LV function by comparing Doppler, invasive, computed tomography (CT) LV outflow tract (LVOT) area, and calcium score (CaSc). Results: Thirty-six patients had discordant echocardiographic findings (mean gradient < 40 mmHg, AV area ≤ 1 cm2). Of those, 19 had discordant invasive measurements (true discordant [TD]) and 17 concordant (false discordant [FD]): In 12 of the FD the mean gradient was > 30 mmHg; technical pitfalls were found in 10 patients (no reliable right parasternal Doppler in 6). LVOT area by echocardiography or CT could not differentiate between concordants and discordants nor between TD and FD (p = NS). CaSc was similar in concordants and FD (p = 0.3), and it was higher in true concordants than in TD (p = 0.005). CaSc positive predictive value for the correct diagnosis of severe AS was 95% for concordants and 93% for discordants. Conclusions: Discordant echocardiographic findings are commonly found in patients with symptomatic AS. Underestimation of the true mean gradient due to technical difficulties is an important cause of these discrepant findings. LVOT area by echocardiography or CT cannot differentiate between TD and FD. In the absence of a reliable and compete multi-window Doppler evaluation, patients should undergo CaSc assessment

Linear square-mass trajectories of radially and orbitally excited hadrons in holographic QCD

We consider a new approach towards constructing approximate holographic duals of QCD from experimental hadron properties. This framework allows us to derive a gravity dual which reproduces the empirically found linear square-mass trajectories of universal slope for radially and orbitally excited hadrons. Conformal symmetry breaking in the bulk is exclusively due to infrared deformations of the anti-de Sitter metric and governed by one free mass scale proportional to Lambda_QCD. The resulting background geometry exhibits dual signatures of confinement and provides the first examples of holographically generated linear trajectories in the baryon sector. The predictions for the light hadron spectrum include new relations between trajectory slopes and ground state masses and are in good overall agreement with experiment.Comment: 33 pages, 5 figures, updated to the extended version published in JHEP, vector meson bulk potential and metric corrected, comments and references added, phenomenology and conclusions unchange

Herding Cats: Modelling, Simulation, Testing, and Data Mining for Weak Memory

We propose an axiomatic generic framework for modelling weak memory. We show how to instantiate this framework for SC, TSO, C++ restricted to release-acquire atomics, and Power. For Power, we compare our model to a preceding operational model in which we found a flaw. To do so, we define an operational model that we show equivalent to our axiomatic model. We also propose a model for ARM. Our testing on this architecture revealed a behaviour later acknowl-edged as a bug by ARM, and more recently 31 additional anomalies. We offer a new simulation tool, called herd, which allows the user to specify the model of his choice in a concise way. Given a specification of a model, the tool becomes a simulator for that model. The tool relies on an axiomatic description; this choice allows us to outperform all previous simulation tools. Additionally, we confirm that verification time is vastly improved, in the case of bounded model checking. Finally, we put our models in perspective, in the light of empirical data obtained by analysing the C and C++ code of a Debian Linux distribution. We present our new analysis tool, called mole, which explores a piece of code to find the weak memory idioms that it uses

Update of D3/D7-Brane Inflation on K3 x T^2/Z_2

We update the D3/D7-brane inflation model on K3 x T^2/Z_2 with branes and fluxes. For this purpose, we study the low energy theory including g_s corrections to the gaugino condensate superpotential that stabilizes the K3 volume modulus. The gauge kinetic function is verified to become holomorphic when the original N=2 supersymmetry is spontaneously broken to N=1 by bulk fluxes. From the underlying classical N=2 supergravity, the theory inherits a shift symmetry which provides the inflaton with a naturally flat potential. We analyze the fate of this shift symmetry after the inclusion of quantum corrections. The field range of the inflaton is found to depend significantly on the complex structure of the torus but is independent of its volume. This allows for a large kinematical field range for the inflaton. Furthermore, we show that the D3/D7 model may lead to a realization of the recent CMB fit by Hindmarsh et al. with an 11% contribution from cosmic strings and a spectral index close to n_s=1. On the other hand, by a slight change of the parameters of the model one can strongly suppress the cosmic string contribution and reduce the spectral index n_s to fit the WMAP5 data in the absence of cosmic strings. We also demonstrate that the inclusion of quantum corrections allows for a regime of eternal D3/D7 inflation.Comment: LaTeX2e, 55 pages + appendices, 8 figures; v3: added appendix F and a note at the end of the conclusions in order to clarify the relation of our results to the recent work by Burgess et al. (arXiv:0811.1503

Glueballs vs. Gluinoballs: Fluctuation Spectra in Non-AdS/Non-CFT

Building on earlier results on holographic bulk dynamics in confining gauge theories, we compute the spin-0 and spin-2 spectra of gauge theories dual to the non-singular Maldacena-Nunez and Klebanov-Strassler supergravity backgrounds. We construct and apply a numerical recipe for computing mass spectra from certain determinants. In the Klebanov-Strassler case, states containing the glueball and gluinoball obey "quadratic confinement", i.e. their mass-squareds depend on consecutive number as m^2 ~ n^2 for large n, with a universal proportionality constant. The hardwall approximation appears to work poorly when compared to the unique spectra we find in the full theory with a smooth cap-off in the infrared.Comment: 50 pages, 6 figures. v2: corrected typos, added reference