152 research outputs found
Sequence of penalties method to study excited states using VQE
We propose an extension of the Variational Quantum Eigensolver (VQE) that
leads to more accurate energy estimations and can be used to study excited
states. The method is based on the introduction of a sequence of increasing
penalties in the cost function. This approach does not require circuit
modifications and thus can be applied with no additional depth cost. Through
numerical simulations, we show that we are able to produce variational states
with desired physical properties, such as total spin and charge. We assess its
performance both on classical simulators and on currently available quantum
devices, calculating the potential energy curves of small molecular systems in
different physical configurations. Finally, we compare our method to the
original VQE and to another extension, obtaining a better agreement with exact
simulations for both energy and targeted physical quantities.Comment: 11 pages, 9 figures, accepted in IOP Quantum Science and Technolog
Leiomyosarcoma of the inferior vena cava in a patient with Budd-Chiari syndrome.
A 65-year-old man with no history of cardiovascular disease was admitted because of abdominal pain, nausea and lower limb edema. At clinical examination he presented hepatomegaly, ascites and laboratory evidence of liver failure. The echocardiogram (Figure 1A) showed preserved biventricular function, but a large irregular mass was visible in the right atrium (arrow; Supplementary data, Movie 1 and 2). Computed tomography (Figure 1B) showed patchy contrast uptake and positron emission tomography (Figure 1C) showed pathological uptake of 18-fluoro-deoxyglucose in the mass (arrow), extending along the inferior vena cava (arrowheads), suggesting a neoplastic nature. At cardiovascular magnetic resonance (Figure 1D and E; Supplementary data, Movie 3 and 4) the mass involved the right atrium (arrow) and extended into the inferior vena cava (arrowheads); moreover, it presented irregular contours and signal characteristics typical of a neoplastic mass
Restrictive cardiomyopathy: definition and diagnosis
Restrictive cardiomyopathy (RCM) is a heterogeneous group of diseases characterized by restrictive left ventricular pathophysiology, i.e. a rapid rise in ventricular pressure with only small increases in filling volume due to increased myocardial stiffness. More precisely, the defining feature of RCM is the coexistence of persistent restrictive pathophysiology, diastolic dysfunction, non-dilated ventricles, and atrial dilatation, regardless of ventricular wall thickness and systolic function. Beyond this shared haemodynamic hallmark, the phenotypic spectrum of RCM is wide. The disorders manifesting as RCM may be classified according to four main disease mechanisms: (i) interstitial fibrosis and intrinsic myocardial dysfunction, (ii) infiltration of extracellular spaces, (iii) accumulation of storage material within cardiomyocytes, or (iv) endomyocardial fibrosis. Many disorders do not show restrictive pathophysiology throughout their natural history, but only at an initial stage (with an evolution towards a hypokinetic and dilated phenotype) or at a terminal stage (often progressing from a hypertrophic phenotype). Furthermore, elements of both hypertrophic and restrictive phenotypes may coexist in some patients, making the classification challenge. Restrictive pathophysiology can be demonstrated by cardiac catheterization or Doppler echocardiography. The specific conditions may usually be diagnosed based on clinical data, 12-lead electrocardiogram, echocardiography, nuclear medicine, or cardiovascular magnetic resonance, but further investigations may be needed, up to endomyocardial biopsy and genetic evaluation. The spectrum of therapies is also wide and heterogeneous, but disease-modifying treatments are available only for cardiac amyloidosis and, partially, for iron overload cardiomyopathy
Myocardial fibrosis as a key determinant of left ventricular remodeling in idiopathic dilated cardiomyopathy: a contrast-enhanced cardiovascular magnetic study
In idiopathic dilated cardiomyopathy, there are scarce data on the influence of late gadolinium enhancement (LGE) assessed by cardiovascular magnetic resonance on left ventricular (LV) remodeling
What Is Hidden Behind Inferior Negative T Waves: Multiple Cardiac Glomangiomas
Abstract Negative T waves in the inferior leads in an asymptomatic 17-year-old female patient prompted a diagnostic evaluation disclosing the presence of multiple cardiac glomangiomas. The combination of different imaging modalities (echocardiography, magnetic resonance, and positron emission tomography/computed tomography) and myocardial biopsy was crucial to establishing the correct diagnosis. (Level of Difficulty: Advanced.
Electrocardiographic abnormalities in patients with cardiomyopathies
Abnormalities in impulse generation and transmission are among the first signs of cardiac remodeling in cardiomyopathies. Accordingly, 12-lead electrocardiogram (ECG) of patients with cardiomyopathies may show multiple abnormalities. Some findings are suggestive of specific disorders, such as the discrepancy between QRS voltages and left ventricular (LV) mass for cardiac amyloidosis or the inverted T waves in the right precordial leads for arrhythmogenic cardiomyopathy. Other findings are less sensitive and/or specific, but may orient toward a specific diagnosis in a patient with a specific phenotype, such as an increased LV wall thickness or a dilated LV. A “cardiomyopathy-oriented” mindset to ECG reading is important to detect the possible signs of an underlying cardiomyopathy and to interpret correctly the meaning of these alterations, which differs in patients with cardiomyopathies or other conditions
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