Geodesics in minimal surfaces Riveros, Carlos M. C.; Corro, Armando M. V.
Mathematical Notes,
03/2017, Letnik:
101, Številka:
3-4
Journal Article
Recenzirano
—In this paper, we consider connected minimal surfaces in R
3
with isothermal coordinates and with a family of geodesic coordinates curves, these surfaces will be called
GICM-surfaces
. We give a ...classification of the GICM-surfaces. This class of minimal surfaces includes the catenoid, the helicoid and Enneper’s surface. Also, we show that one family of this class of minimal surfaces has at least one closed geodesic and one 1-periodic family of this class has finite total curvature. As application we show other characterization of catenoid and helicoid. Finally, we show that the class of GICM-surfaces coincides with the class of minimal surfaces whose the geodesic curvature
k
g
1
and
k
g
2
of the coordinates curves satisfy
αk
g
1
+
βk
g
2
= 0, α, β ∈ R.
The one-body reduced density matrix γ plays a fundamental role in describing and predicting quantum features of bosonic systems, such as Bose-Einstein condensation. The recently proposed reduced ...density matrix functional theory for bosonic ground states establishes the existence of a universal functional Fγ that recovers quantum correlations exactly. Based on a decomposition of γ, we have developed a method to design reliable approximations for such universal functionals: Our results suggest that for translational invariant systems the constrained search approach of functional theories can be transformed into an unconstrained problem through a parametrization of a Euclidian space. This simplification of the search approach allows us to use standard machine learning methods to perform a quite efficient computation of both Fγ and its functional derivative. For the Bose-Hubbard model, we present a comparison between our approach and the quantum Monte Carlo method.
Surgical patients can be discharged to a variety of facilities which vary widely in intensity of care. Postoperative readmissions have been found to be more strongly associated with post-discharge ...events than pre-discharge complications, indicating the importance of discharge destination. We sought to evaluate the association between discharge destination and 30-day outcomes. A retrospective cohort study was conducted using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. Patients were dichotomized based on discharge destination: home versus non-home. The main outcome of interest was 30-day unplanned readmission. The secondary outcomes included post-discharge pulmonary, infectious, thromboembolic, and bleeding complications, as well as death. In this cohort study of over 1.5 million patients undergoing common surgical procedures across eight surgical specialties, we found non-home discharge to be associated with adverse 30-day post-operative outcomes, namely, unplanned readmissions, post-discharge pulmonary, infectious, thromboembolic, and bleeding complications, as well as death. Non-home discharge is associated with worse 30-day outcomes among patients undergoing common surgical procedures. Patients and caregivers should be counseled regarding discharge destination, as non-home discharge is associated with adverse post-operative outcomes.
Retrograde ureteroscopy with holmium laser lithotripsy (HLL) is a standard treatment for urolithiasis. Moses technology has been shown to improve fragmentation efficiency in vitro; however, it is ...still unclear how it performs clinically compared to standard HLL. We performed a systematic review and meta-analysis evaluating the differences in efficiency and outcomes between Moses mode and standard HLL.
We searched the MEDLINE, EMBASE, and CENTRAL databases for randomized clinical trials and cohort studies comparing Moses mode and standard HLL in adults with urolithiasis. Outcomes of interest included operative (operation, fragmentation, and lasing times; total energy used; and ablation speed) and perioperative parameters (stone-free rate and overall complication rate).
The search identified six studies eligible for analysis. Compared to standard HLL, Moses was associated with significantly shorter average lasing time (mean difference MD -0.95, 95% confidence interval CI -1.22 to -0.69 minutes), faster stone ablation speed (MD 30.45, 95% CI 11.56-49.33 mm
/min), and higher energy used (MD 1.04, 95% CI 0.33-1.76 kJ). Moses and standard HLL were not significantly different in terms of operation (MD -9.89, 95% CI -25.14 to 5.37 minutes) and fragmentation times (MD -1.71, 95% CI -11.81 to 8.38 minutes), as well as stone-free (odds ratio OR 1.04, 95% CI 0.73-1.49) and overall complication rates (OR 0.68, 95% CI 0.39-1.17).
While perioperative outcomes were equivalent between Moses and standard HLL, Moses was associated with faster lasing time and stone ablation speeds at the expense of higher energy usage.
Congruencias de esferas geodésicas em H3 e S3 S. Reyes, Edwin; C. Riveros, Carlos
Selecciones matemáticas : revista científica del Departamento Académico de Matemáticas,
12/2018, Letnik:
5, Številka:
2
Journal Article
Recenzirano
Odprti dostop
In 2, was obtained a characterization of the surfaces in R3 which are envelopes of a sphere congruence in R3, in which the other envelope is in R2. In this paper, we characterize the surfaces of H3 ...and S3 which are envelopes of a congruence of geodesic spheres in H3 and S3, respectively, in which the other envelope is contained in H2 H3and S2 S3. We show that this characterization allows locally to obtain a parameterization of the surfaces contained in H3 and S3, this characterization extends the result obtained in 2. Moreover, we provide sufficient conditions for these surfaces to be locally associated by a transformation of Ribaucour. Also, we present families of surfaces parameterized by lines of curvature in H3 and S3, which depend on a function of two variables which is solution of a differential equation. Finally, we characterize the surfaces of the spherical type in H3 and S3, as the surfaces where its radius function is the solution of the Helmholtz equation.
Em 2, foi obtida uma caracterização das superfícies em R3 que são envelopes de uma congruência de esferas em R3, na qual o outro envelope está em R2. Neste artigo, caracterizamos as superfícies de H3 e S3 que são envelopes de uma congruência de esferas geodésicas em H3 e S3, respectivamente, na qual o outro envelope está contido em H2 H3 e S2 S3. Mostramos que esta caracterização permite obter localmente uma parametrização das superfícies contidas em H3 e S3, esta caracterização estende o resultado obtido em 2. Além disso, damos condições suficientes para que estas superficies estejam associadas localmente por uma transformação de Ribaucour. Também, apresentamos famílias de superfícies parametrizadas por linhas de curvatura H3 e S3, que dependem unicamente de uma função de duas variavéis, a qual é solução de uma equação diferencial. Finalmente, caracterizamos as superfícies de tipo esférico em H3 e S3, como as superfícies onde sua função raio é solução da equação de Helmholtz.
Quantum Fisher information (QFI) is a central concept in quantum sciences used to quantify the ultimate precision limit of parameter estimation, detect quantum phase transitions, witness genuine ...multipartite entanglement, or probe nonlocality. Despite this widespread range of applications, computing the QFI value of quantum many-body systems is, in general, a very demanding task. Here we combine ideas from functional theories and quantum information to develop a functional framework for the QFI of fermionic and bosonic ground states. By relying upon the constrained-search approach, we demonstrate that the QFI matrix terms can universally be determined by the one-body reduced density matrix (1-RDM), thus avoiding the use of exponentially large wave functions. Furthermore, we show that QFI functionals can be determined from the universal 1-RDM functional by calculating its derivatives with respect to the coupling strengths, thus becoming the generating functional of the QFI. We showcase our approach with the Bose-Hubbard model and present exact analytical and numerical QFI functionals. Our results provide the first connection between the one-body reduced density matrix functional theory and the quantum Fisher information.
Objetivo: Las condiciones topográficas y altas especificaciones técnicas de los recientes proyectos de infraestructura vial ejecutados por el gobierno colombiano ha impulsado la construcción de ...numerosos puentes segmentales. La Norma Colombiana de Diseño de Puentes – LRFD – CCP 14 no establece criterios específicos para la evaluación de puentes nuevos que permitan la evaluación estructural. Con el objetivo de fomentar la implementación de pruebas dinámicas en puentes segmentales se presenta un estudio de identificación de parámetros influyentes en la caracterización dinámica usando vibración forzada. Metodología: Con base en los parámetros identificados, se ejecutó un conjunto de simulaciones numéricas usando herramientas computacionales específicamente en análisis de historia tiempo para análisis de aceleraciones producto de circulación de vehículos pesados a distintas velocidades. Resultados: Se desarrolló un enfoque analítico para selección de velocidades de circulación para distintos tipos de vehículos de prueba. Conclusiones: lo que permite obtener un conjunto de variables óptimas como velocidad, peso, posición de impacto y frenado para la ejecución de pruebas de vibración forzada que permitan complementar los resultados que se obtienen de pruebas de vibración ambiental.
In this paper we study Dupin hypersurfaces in \mathbb R^4
parametrized by lines of curvature, with three distinct principal
curvatures and m_{jik}= 0. We characterize locally a generic family
of such ...hypersurfaces in terms of the principal curvatures and three
vector valued functions of one variable, which are invariant under
inversions and homotheties.
Objective: We sought to examine whether the outcomes of patients who receive a surgical procedure on Friday the 13th differ from patients who receive surgery on flanking Fridays. Background: Numerous ...studies have demonstrated that increased anxiety from the provider or patient around the time of surgery can lead to worse outcomes. Superstitious patients often express significant concern and anxiety when undergoing a surgical procedure on Friday the 13th. Methods: A retrospective, population-based cohort study of 19,747 adults undergoing 1 of 25 common surgical procedures on Friday the 13th or flanking control Fridays (Friday the 6th and Friday the 20th) between January 1, 2007, and December 31, 2019, with 1 year of follow-up. The main outcomes included death, readmission, and complications at 30 days (short-term), 90 days (intermediate-term), and 1 year (long-term). Results: A total of 7,349 (37.2%) underwent surgery on Friday the 13th, and 12,398 (62.8%) underwent surgery on a flanking Friday during the study period. Patient characteristics were similar between the 2 groups. We found no evidence that patients receiving surgery on Friday the 13th group were more likely to experience the composite primary outcome at 30 days adjusted odds ratio (aOR) = 1.02 (95% CI = 0.94–1.09), 90 days aOR = 0.97 (95% CI = 0.90–1.04), and 1 year aOR = 0.99 (95% CI = 0.94–1.04) after surgery. Conclusion: Patients receiving surgery on Friday the 13th do not appear to fare worse than those treated on ordinary Fridays with respect to the composite outcome.
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