P-POSSUM - Preditor de mortalidade e morbilidade em cistectomias radicais?

Introdução: A predição do risco pré-operatório pode ser um dado útil na tomada da decisão cirúrgica. O P-POSSUM (Portsmouth POSSUM - Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity) é um sistema baseado em variáveis fisiológicas e cirúrgicas, validado para cirurgia geral, que estima a mortalidade e morbilidade de cada doente aos 30 dias após a cirurgia (1). Em grandes séries de doentes submetidos a cistectomia radical estão descritas taxas de 2,5 e 28%, respetivamente (2). Pretendeu-se avaliar a aplicabilidade deste sistema em doentes submetidos a cistectomia radical num hospital central. Métodologia: Foi realizada uma análise retrospetiva, através da consulta dos registos electrónicos, dos parâmetros fisiológicos, cirúrgicos, morbilidade e mortalidade aos 30 dias de todos os doentes submetidos a cistectomia radical eletiva num hospital central, durante um ano. Foi aplicado o sistema P-POSSUM e calculadas as razões observada/prevista para morbilidade e mortalidade aos 30 dias. Resultados: Foram incluídos 28 doentes, com idade média de 70 anos, 78.6% do sexo masculino. Ocorreram 2 mortes (7.1%) e 14 doentes (50%) tiveram pelo menos uma complicação no pós-operatório. As complicações mais frequentes foram hemorragia, deiscência de anastomoses e infeção da ferida cirúrgica. A mortalidade prevista pela aplicação do sistema P-POSSUM foi de 9.2% e a morbilidade média prevista foi de 71.4%. As razões observada/prevista para a mortalidade e a morbilidade foram, respetivamente, 0.77 e 0.7. Discussão e Conclusões: Na amostra populacional estudada, o sistema P-POSSUM revelou-se um excelente preditor da morbilidade e da mortalidade associada a cistectomias radicais. Embora pareça sobrestimar os seus valores, estes resultados coincidem com os apresentados em estudos recentemente publicados. As complicações pós-cirúrgicas mais frequentes estão de acordo com o descrito na literatura até à data. Assim, o sistema P-Possum poderá ser um instrumento útil na predição de risco cirúrgico durante a avaliação individual de doentes propostos para cistectomia radical

Role of mixed permutation symmetry sectors in the thermodynamic limit of critical three-level Lipkin-Meshkov-Glick atom models

We introduce the notion of Mixed Symmetry Quantum Phase Transition (MSQPT) as singularities in the transformation of the lowest-energy state properties of a system of identical particles inside each permutation symmetry sector $\mu$, when some Hamiltonian control parameters $\lambda$ are varied. We use a three-level Lipkin-Meshkov-Glick (LMG) model, with $U(3)$ dynamical symmetry, to exemplify our construction. After reviewing the construction of $U(3)$ unirreps using Young tableaux and Gelfand basis, we firstly study the case of a finite number $N$ of three-level atoms, showing that some precursors (fidelity-susceptibility, level population, etc.) of MSQPTs appear in all permutation symmetry sectors. Using coherent (quasi-classical) states of $U(3)$ as variational states, we compute the lowest-energy density for each sector $\mu$ in the thermodynamic $N\to\infty$ limit. Extending the control parameter space by $\mu$, the phase diagram exhibits four distinct quantum phases in the $\lambda$-$\mu$ plane that coexist at a quadruple point. The ground state of the whole system belongs to the fully symmetric sector $\mu=1$ and shows a four-fold degeneracy, due to the spontaneous breakdown of the parity symmetry of the Hamiltonian. The restoration of this discrete symmetry leads to the formation of four-component Schr\"odinger cat states.Comment: 15 pages, 9 figure

Higher-U(2,2)-spin fields and higher-dimensional W-gravities: quantum AdS space and radiation phenomena

A physical and geometrical interpretation of previously introduced tensor operator algebras of U(2,2) in terms of algebras of higher-conformal-spin quantum fields on the anti-de Sitter space AdS_5 is provided. These are higher-dimensional W-like algebras and constitute a potential gauge guide principle towards the formulation of induced conformal gravities (Wess-Zumino-Witten-like models) in realistic dimensions. Some remarks on quantum (Moyal) deformations are given and potentially tractable versions of noncommutative AdS spaces are also sketched. The role of conformal symmetry in the microscopic description of Unruh and Hawking's radiation effects is discussed.Comment: LaTeX, 30 pages, 2 figures, final version to appear in Class. and Quant. Gra

Sampling Theorem and Discrete Fourier Transform on the Riemann Sphere

Using coherent-state techniques, we prove a sampling theorem for Majorana's (holomorphic) functions on the Riemann sphere and we provide an exact reconstruction formula as a convolution product of $N$ samples and a given reconstruction kernel (a sinc-type function). We also discuss the effect of over- and under-sampling. Sample points are roots of unity, a fact which allows explicit inversion formulas for resolution and overlapping kernel operators through the theory of Circulant Matrices and Rectangular Fourier Matrices. The case of band-limited functions on the Riemann sphere, with spins up to $J$, is also considered. The connection with the standard Euler angle picture, in terms of spherical harmonics, is established through a discrete Bargmann transform.Comment: 26 latex pages. Final version published in J. Fourier Anal. App

Signatures of topological phase transitions in higher Landau levels of HgTe/CdTe quantum wells from an information theory perspective

We analyze the structure of low energy Hamiltonian eigenstates in zincblende heterostructures (like HgTe/CdTe quantum wells) near the gamma point, under magnetic fields, to characterize topological phase transitions (TPT) under an information-theoretic perspective. Using information markers like entanglement, quantum fluctuations, fidelity susceptibility, participation ration, area in phase space, etc., we realize that higher Landau levels (LL) feel the topological phase transition slightly displaced with regard to the edge state, thus leading to the concept of ‘‘higher Landau level |n| > 0 TPT’’, as ‘‘echoes’’ of the standard edge state n = 0 TPT. We compute the critical magnetic field and the critical HgTe layer thickness at which these information measures of higher Landau levels undergo a structural change.PGC2018-097831-B-I00UHU-1262561 and FQM-381Universidad de Granada / CBU