Search

Takeshi Yokoo,1 Amish D Patel,1 Naama Lev-Cohain,1 Amit G Singal,2 Adam C Yopp,3 Ivan Pedrosa1 1Department of Radiology, 2Department of Internal Medicine, 3Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX, USA Background: Extrahepatic metastases have important implications in the clinical management of hepatocellular carcinoma (HCC). The purpose of this study was to validate tumor staging parameters and serum AFP as risk factors of HCC metastasis.Patients and methods: In this retrospective case–control study, patients with a new diagnosis of HCC (N=236), median age 57 years (range 28–89 years), and male-to-female ratio of 183/53 were divided into a “no-met” group (N=101) without extrahepatic metastasis or a “met” group with extrahepatic metastases (N=135). Metastasis risk factors based on tumor staging parameters (size, number, infiltration, and vascular invasion) and serum AFP level were calculated as odds ratio (OR). Sensitivities of the risk factors as metastasis screening tests were also calculated.Results: AFP >400 mg/mL, index tumor size >5 cm, and vascular invasion individually had strong association with metastasis, with OR (95% confidence interval) of 11.5 (5.9–22.1), 17.7 (9.0–34.8), and 18.9 (8.2–43.9), respectively, but with moderate sensitivities as metastasis screening tests, with 71.9% (65.7–77.3), 75.6% (69.6–80.7), and 58.5% (52.1–64.7), respectively. Composite multiparametric criteria, eg, a logical union of 1) tumor size outside of Milan criteria, 2) AFP threshold >35 mg/mL, and 3) vascular invasion, had excellent OR up to 55.6 (13.0–237.1) with screening sensitivity 98.5% (95.8–99.6).Conclusion: Serum AFP, tumor size, and vascular invasion are strongly associated with extrahepatic metastasis of HCC, especially when combined into a multiparametric metastasis prediction criterion. Keywords: hepatocellular carcinoma, risk factor, α-fetoprotein, stage, metastasis

In this work we present a simple and elegant approach to study the adiabatic and nonadiabatic evolution of a generalized damped harmonic oscillator which is described by the generalized Caldirola–Kanai Hamiltonian, in both classical and quantum contexts. Based on time-dependent dynamical invariants, we find that the geometric phase acquired when the damped oscillator evolves adiabatically in time provides a direct connection between the classical Hannay's angle and the quantum Berry's phase. In addition, we solve the time-dependent Schrödinger equation for this system and calculate various quantum properties of the damped generalized harmonic one, such as coherent states, expectation values of the position and momentum operators, their quantum fluctuations and the associated uncertainty product. [ABSTRACT FROM AUTHOR]

In this work, we analyze the quantum dynamics of a generalized pendulum with a time-varying mass increasing exponentially and constant gravitation. By using Lewis–Riesenfeld invariant approach and Fock states, we solve the time-dependent Schrödinger equation for this system and write its solutions in terms of solutions of the Milne–Pinney equation. We also construct coherent states for the quantized pendulum and use both Fock and coherent states to investigate some important physical proprieties of the quantized pendulum such as eigenvalues of the angular displacement and momentum, their quantum variances as well as the respective uncertainty principle. Finally, we derive the geometric, dynamical and Berry phases for the time-dependent generalized pendulum. [ABSTRACT FROM AUTHOR]

We discuss the quantum theory of an harmonic oscillator with time-dependent mass and frequency submitted to action of a complex time-dependent linear potential with 𝒫 𝒯 symmetry. Combining the Lewis and Riesenfeld approach to time-dependent non-Hermitian Hamiltonians having 𝒫 𝒯 symmetry and linear invariants, we solve the time-dependent Schrödinger equation for this problem and use the corresponding quantum states to construct a Gaussian wave packet solution. We show that the shape of this wave packet does not depend on the driving force. Afterwards, using this wave packet state, we calculate the expectation values of the position and momentum, their fluctuations and the associated uncertainty product. We find that these expectation values are complex numbers and as a consequence the position and momentum operators are not physical observables and the uncertainty product is physically unacceptable. [ABSTRACT FROM AUTHOR]

In this work, we solve the time-independent Schrödinger equation for a Landau system modulated by a non-Hermitian Hamiltonian. The system consists of a spinless particle in a uniform magnetic field submitted to action of a non- 𝒫 𝒯 symmetric complex potential. Although the Hamiltonian is neither Hermitian nor 𝒫 𝒯 -symmetric, we find that the Landau problem under study exhibits an entirely real energy spectrum. [ABSTRACT FROM AUTHOR]

We discuss the problem of a mesoscopic LC circuit with a negative inductance ruled by a time-dependent Hermitian Hamiltonian. Classically, we find unusual expressions for the Faraday's law and for the inductance of a solenoid. Quantum mechanically, we solve exactly the time-dependent Schrödinger equation through the Lewis and Riesenfeld invariant operator method and construct Gaussian wave packet solutions for this time-dependent LC circuit. We also evaluate the expectation values of the charge and the magnetic flux in these Gaussian states, their quantum fluctuations and the corresponding uncertainty product. [ABSTRACT FROM AUTHOR]

In this paper, we study the coherent states of Landau-Aharonov-Casher (LAC) levels. These LAC levels are an analogue of the Landau quantization for neutral particles. Afterwards, we investigate some properties of the coherent states, evaluate the uncertainty product and derive the wave functions for our problem. We also discuss the coherent states for the Landau-He-McKellar-Wilkens (LHMW) levels by using the Maxwell duality. [ABSTRACT FROM AUTHOR]

In this paper, we study the generalized harmonic oscillator with arbitrary time-dependent mass and frequency subjected to a linear velocity-dependent frictional force from classical and quantum points of view. We obtain the solution of the classical equation of motion of this system for some particular cases and derive an equation of motion that describes three different systems. Furthermore, with the help of the quantum invariant method and using quadratic invariants we solve analytically and exactly the time-dependent Schrödinger equation for this system. Afterwards, we construct coherent states for the quantized system and employ them to investigate some of the system's quantum properties such as quantum fluctuations of the coordinate and the momentum as well as the corresponding uncertainty product. In addition, we derive the geometric, dynamical and Berry phases for this nonstationary system. Finally, we evaluate the dynamical and Berry phases for three special cases and surprisingly find identical expressions for the dynamical phase and the same formulae for the Berry's phase. [ABSTRACT FROM AUTHOR]

In this paper, we use Hermitian linear invariants and the Lewis and Riesenfeld invariant method to obtain the general solution of the Schrödinger equation for a mesoscopic RLC circuit with time-dependent resistance, inductance, capacitance and a power source and represent it in terms of an arbitrary weight function. In addition, we construct Gaussian wave packet solutions for this electromagnetic oscillation circuit and employ them to calculate the quantum fluctuations of the charge and the magnetic flux as well as the associated uncertainty product. We also show that the width of the Gaussian packet and the fluctuations do not depend on the external power. [ABSTRACT FROM AUTHOR]

Objectives: To assess the value of dynamic contrast-enhanced (DCE) combined with T2-weighted (T2W) endorectal coil (ERC) magnetic resonance imaging (MRI) at 3 T for determining extracapsular extension (ECE) of prostate cancer.Methods: In this IRB-approved study, ERC 3-T MRI of the prostate was performed in 108 patients before radical prostatectomy. T2W fast spin-echo and DCE 3D gradient echo images were acquired. The interpretations of readers with varied experience were analysed. MRI-based staging results were compared with radical prostatectomy histology. Descriptive statistics were generated for prediction of ECE and staging accuracies were determined by the area under the receiver-operating characteristic curve.Results: The overall sensitivity, specificity, positive predictive value and negative predictive value for ECE were 75 %, 92 %, 79 % and 91 %, respectively. Diagnostic accuracy for staging was 86 %, 80 % and 91 % for all readers, experienced and less experienced readers, respectively.Conclusions: ERC 3-T MRI of the prostate combining DCE and T2W imaging is an accurate pretherapeutic staging tool for assessment of ECE in clinical practice across varying levels of reader experience.Key Points: • Endorectal coil (ERC) magnetic resonance imaging is widely used for imaging prostatic disease. • ERC 3-T MRI is reasonably accurate for local prostate cancer staging. • High diagnostic accuracy is achievable across different levels of reader experience. • MRI facilitates therapeutic decisions in patients with prostate cancer. [ABSTRACT FROM AUTHOR]

In this work, we investigate the quantum effects of relic gravitons from a Schrödinger-picture point of view. By considering the gravity-wave equations in the Friedmann–Robertson–Walker cosmological background, we reduce the problem to that of a generalized time-dependent harmonic oscillator and find the corresponding exact analytic wave functions with the help of the dynamical invariant operator method. Afterward, we derive the geometric phases and squeezed quantum states for this system. We also evaluate the quantum fluctuations and the uncertainty product for each mode of the quantized field. [ABSTRACT FROM AUTHOR]

In this work, we study quantum effects of a massive scalar field in the de Sitter spacetime. We reduce the problem to that of a time-dependent harmonic oscillator and use exact linear invariants and the dynamic invariant method to derive the corresponding Schrödinger states in terms of solutions of a second order ordinary differential equation. Afterwards, we construct Gaussian wave packet states and calculate the quantum dispersions as well as the quantum correlations for each mode of the quantized scalar field. It is further shown that the center of the Gaussian wave packet remains trapped in the origin. [ABSTRACT FROM AUTHOR]