Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Más filtros












Base de datos
Intervalo de año de publicación
1.
Sci Rep ; 14(1): 13876, 2024 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-38880865

RESUMEN

This study presents a new mathematical framework for analyzing the behavior of semiconductor elastic materials subjected to an external magnetic field. The framework encompasses the interaction between plasma, thermal, and elastic waves. A novel, fully coupled mathematical model that describes the plasma thermoelastic behavior of semiconductor materials is derived. Our new model is applied to obtain the solution to Danilovskaya's problem, which is formed from an isotropic homogeneous semiconductor material. The Laplace transform is utilized to get the solution in the frequency domain using a direct approach. Numerical methods are employed to calculate the inverse Laplace transform, enabling the determination of the solution in the physical domain. Graphical representations are utilized to depict the numerical outcomes of many physical fields, including temperature, stress, displacement, chemical potential, carrier density, and current carrier distributions. These representations are generated for different values of time and depth of the semiconductor material. Ultimately, we receive a comparison between our model and several earlier fundamental models, which is then graphically represented.

2.
J Comput Biol ; 31(8): 727-741, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38923891

RESUMEN

While the world recovers from the COVID-19 pandemic, another outbreak of contagious disease remains the most likely future risk to public safety. Now is therefore the time to equip health authorities with effective tools to ensure they are operationally prepared for future events. We propose a direct approach to obtain reliable nearly instantaneous time-varying reproduction numbers for contagious diseases, using only the number of infected individuals as input and utilising the dynamics of the susceptible-infected-recovered (SIR) model. Our approach is based on a multivariate nonlinear regression model simultaneously assessing parameters describing the transmission and recovery rate as a function of the SIR model. Shortly after start of a pandemic, our approach enables estimation of daily reproduction numbers. It avoids numerous sources of additional variation and provides a generic tool for monitoring the instantaneous reproduction numbers. We use Norwegian COVID-19 data as case study and demonstrate that our results are well aligned with changes in the number of infected individuals and the change points following policy interventions. Our estimated reproduction numbers are notably less volatile, provide more credible short-time predictions for the number of infected individuals, and are thus clearly favorable compared with the results obtained by two other popular approaches used for monitoring a pandemic. The proposed approach contributes to increased preparedness to future pandemics of contagious diseases, as it can be used as a simple yet powerful tool to monitor the pandemics, provide short-term predictions, and thus support decision making regarding timely and targeted control measures.


Asunto(s)
Número Básico de Reproducción , COVID-19 , Dinámicas no Lineales , Pandemias , SARS-CoV-2 , Humanos , COVID-19/epidemiología , COVID-19/transmisión , COVID-19/prevención & control , COVID-19/virología , Número Básico de Reproducción/estadística & datos numéricos , Noruega/epidemiología , Análisis de Regresión
3.
Molecules ; 29(6)2024 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-38542892

RESUMEN

The selection of a "perfect tool" for the theoretical determination of acid-base dissociation constants (Ka) is still puzzling. Recently, we developed a user-friendly model exploiting CAM-B3LYP for determining pKa with impressive reliability. Herein, a new challenge is faced, examining a panel of functionals belonging to different rungs of the "Jacob's ladder" organization, which classifies functionals according to their level of theory. Specifically, meta-generalized gradient approximations (GGAs), hybrid-GGAs, and the more complex range-separated hybrid (RSH)-GGAs were investigated in predicting the pKa of differently substituted carboxylic acids. Therefore, CAM-B3LYP, WB97XD, B3PW91, PBE1PBE, PBEPBE and TPSSTPSS were used, with 6-311G+(d,p) as the basis set and the solvation model based on density (SMD). CAM-B3LYP showed the lowest mean absolute error value (MAE = 0.23) with relatively high processing time. PBE1PBE and B3PW91 provided satisfactory predictions (MAE = 0.34 and 0.38, respectively) with moderate computational time cost, while PBEPBE, TPSSTPSS and WB97XD led to unreliable results (MAE > 1). These findings validate the reliability of our model in predicting carboxylic acids pKa, with MAE well below 0.5 units, using a simplistic theoretical level and a low-cost computational approach.

4.
Pract Lab Med ; 39: e00382, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38463194

RESUMEN

Objectives: The direct approach for determining reference intervals (RIs) is not always practical. This study aimed to generate evidence that a real-world data (RWD) approach could be applied to transfer free thyroxine RIs determined in one population to a second population, presenting an alternative to performing multiple RI determinations. Design and methods: Two datasets (US, n = 10,000; Europe, n = 10,000) were created from existing RWD. Descriptive statistics, density plots and cumulative distributions were produced for each data set and comparisons made. Cumulative probabilities at the lower and upper limits of the RIs were identified using an empirical cumulative distribution function. According to these probabilities, estimated percentiles for each dataset and estimated differences between the two sets of percentiles were obtained by case resampling bootstrapping. The estimated differences were then evaluated against a pre-determined acceptance criterion of ≤7.8% (inter-individual biological variability). The direct approach was used to validate the RWD approach. Results: The RWD approach provided similar descriptive statistics for both populations (mean: US = 16.1 pmol/L, Europe = 16.4 pmol/L; median: US = 15.4 pmol/L, Europe = 15.8 pmol/L). Differences between the estimated percentiles at the upper and lower limits of the RIs fulfilled the pre-determined acceptance criterion and the density plots and cumulative distributions demonstrated population homogeneity. Similar RI distributions were observed using the direct approach. Conclusions: This study provides evidence that a RWD approach can be used to transfer RIs determined in one population to another.

5.
Molecules ; 27(23)2022 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-36500683

RESUMEN

Computational chemistry is a valuable tool, as it allows for in silico prediction of key parameters of novel compounds, such as pKa. In the framework of computational pKa determination, the literature offers several approaches based on different level of theories, functionals and continuum solvation models. However, correction factors are often used to provide reliable models that adequately predict pKa. In this work, an accurate protocol based on a direct approach is proposed for computing phenols pKa. Importantly, this methodology does not require the use of correction factors or mathematical fitting, making it highly practical, easy to use and fast. Above all, DFT calculations performed in the presence two explicit water molecules using CAM-B3LYP functional with 6-311G+dp basis set and a solvation model based on density (SMD) led to accurate pKa values. In particular, calculations performed on a series of 13 differently substituted phenols provided reliable results, with a mean absolute error of 0.3. Furthermore, the model achieves accurate results with -CN and -NO2 substituents, which are usually excluded from computational pKa studies, enabling easy and reliable pKa determination in a wide range of phenols.


Asunto(s)
Fenoles , Agua , Termodinámica , Agua/química , Fenoles/química , Teoría Funcional de la Densidad
6.
J Gastrointest Surg ; 25(9): 2358-2367, 2021 09.
Artículo en Inglés | MEDLINE | ID: mdl-33403562

RESUMEN

BACKGROUND: Previous studies have shown that curative resection (R0 resection) was among the most crucial factors for the long-term survival of patients with PHCC. To achieve R0 resection, we performed the transhepatic direct approach and resection on the limits of division of the hepatic ducts. Although a recent report showed that the resection margin (RM) status impacted PHCC patients' survival, it is still unclear whether RM is an important clinical factor. OBJECTIVE: To describe a technique of transhepatic direct approach and resection on the limit of division of hepatic ducts, investigate its short-term surgical outcome, and validate whether the radial margin (RM) would have a clinical impact on long-term survival of perihilar cholangiocarcinoma (PHCC) patients. METHODS: Consecutive PHCC patients (n = 211) who had undergone major hepatectomy with extrahepatic bile duct resection, without pancreaticoduodenectomy, in our department were retrospectively evaluated. RESULTS: R0 resection rate was 92% and 86% for invasive cancer-free and both invasive cancer-free and high-grade dysplasia-free resection, respectively. Overall 5-year survival rate was 46.9%. Univariate analysis showed that preoperative serum carcinoembryonic antigen level (> 7.0 mg/dl), pathological lymph node metastasis, and portal vein invasion were independent risk factors, but R status on both resection margin and bile duct margin was not an independent risk factor for survival. CONCLUSION: The transhepatic direct approach to the limits of division of the bile ducts leads to the highest R0 resection rate in the horizontal margin of PHCC. Further examination will be needed to determine the adjuvant therapy for PHCC to improve patient survival.


Asunto(s)
Neoplasias de los Conductos Biliares , Colangiocarcinoma , Tumor de Klatskin , Neoplasias de los Conductos Biliares/cirugía , Colangiocarcinoma/cirugía , Hepatectomía , Conducto Hepático Común/cirugía , Humanos , Tumor de Klatskin/cirugía , Estudios Retrospectivos , Resultado del Tratamiento
7.
Interv Radiol (Higashimatsuyama) ; 5(1): 1-9, 2020 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-36284832

RESUMEN

PURPOSE: To elucidate the safety and efficacy of embolization using N-butyl cyanoacrylate (NBCA) for endoleaks after abdominal/thoracic endovascular aortic repair (EVAR/TEVAR) via a direct percutaneous approach versus a transarterial approach. MATERIALS AND METHODS: The retrospective design of the study was approved by the institutional ethics committee, and the requirement for informed written consent was waived. Sixteen patients underwent embolization for endoleaks after EVAR/TEVAR, which was diagnosed as type II, from March 2010 to December 2013 at our institution. The number of embolization sessions was 21. A direct percutaneous approach was used in 10 sessions, and a transarterial approach was used in 11 sessions. There were 11 and 15 embolic sites for the two approaches, respectively. The procedure time, amount of contrast media used, therapeutic effect, and complications were evaluated. RESULTS: The mean procedure time (per embolic site) was 100 min (53-170) in the direct percutaneous approach, which was significantly shorter than the 191 min (76-275) in the transarterial approach. The mean amount of contrast media used during the procedure (per embolic site) was 12.8 ml (3-25) by the direct percutaneous approach, which was significantly lesser than the 71.8 ml (30-180) in the transarterial approach. Local control of the embolic site and interval increase in the size of aneurysm after embolization were not significantly different between the two approaches. In one case each, mesenteric hematoma and migration of the embolic agent occurred with a direct percutaneous approach, and a small arterial injury occurred with the transarterial approach; aneurysmal rupture/perianeurysmal hematoma and neurological dysfunction were not observed. CONCLUSION: A direct percutaneous approach is a feasible procedure for embolization of endoleaks after EVAR/TEVAR.

8.
Sensors (Basel) ; 19(10)2019 May 16.
Artículo en Inglés | MEDLINE | ID: mdl-31100933

RESUMEN

Owing to the nonlinearity in visual-inertial state estimation, sufficiently accurate initial states, especially the spatial and temporal parameters between IMU (Inertial Measurement Unit) and camera, should be provided to avoid divergence. Moreover, these parameters are required to be calibrated online since they are likely to vary once the mechanical configuration slightly changes. Recently, direct approaches have gained popularity for their better performance than feature-based approaches in little-texture or low-illumination environments, taking advantage of tracking pixels directly. Based on these considerations, we perform a direct version of monocular VIO (Visual-inertial Odometry), and propose a novel approach to initialize the spatial-temporal parameters and estimate them with all other variables of interest (IMU pose, point inverse depth, etc.). We highlight that our approach is able to perform robust and accurate initialization and online calibration for the spatial and temporal parameters without utilizing any prior information, and also achieves high-precision estimates even when large temporal offset occurs. The performance of the proposed approach was verified through the public UAV (Unmanned Aerial Vehicle) dataset.

9.
Fam Cancer ; 18(1): 43-51, 2019 01.
Artículo en Inglés | MEDLINE | ID: mdl-29651783

RESUMEN

Dissemination of information on a genetically increased risk should according to guidelines primarily be family-mediated. Incomplete and incorrect information spread has, however, been documented and implies missed possibilities for prevention. In Denmark, the national HNPCC register has been granted an exception to send unsolicited letters with information on hereditary colorectal cancer and an invitation to genetic counseling to members of families with familial and hereditary colorectal cancer. To evaluate this approach, we investigated reactions and attitudes to unsolicited letters in 708 members of families with genetic predisposition and in 1600 individuals from the general population. Support for information letters was expressed by 78% of the family members and by 82% of the general population. Regarding route of information, 90% of family members preferred a letter to no information, 66% preferred information from the hospital rather than from family members and 40% preferred to obtain information from a close family member. Our results suggest that use of unsolicited information letters from the health care system may be a feasible and highly acceptable strategy to disseminate information to families at high risk of colorectal cancer.


Asunto(s)
Actitud Frente a la Salud , Neoplasias Colorrectales Hereditarias sin Poliposis/diagnóstico , Asesoramiento Genético/organización & administración , Difusión de la Información/métodos , Sistema de Registros/normas , Adulto , Anciano , Neoplasias Colorrectales Hereditarias sin Poliposis/epidemiología , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/prevención & control , Dinamarca/epidemiología , Detección Precoz del Cáncer , Familia , Estudios de Factibilidad , Femenino , Asesoramiento Genético/normas , Predisposición Genética a la Enfermedad , Pruebas Genéticas , Humanos , Masculino , Persona de Mediana Edad , Educación del Paciente como Asunto , Proyectos Piloto , Servicios Postales , Guías de Práctica Clínica como Asunto , Factores de Riesgo
10.
Australas Phys Eng Sci Med ; 38(4): 695-707, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26206398

RESUMEN

The fracture of the distal ulna and radius is a kind of fracture that results in high morbidity and occurrence rate and contributes to about one-sixth of the entire body's fracture. In this study, we implemented the improved palmar wrist surgery by a volar wrist dual channel approach. Between 2011 and 2014, we have treated 67 distal radius fracture patients. We divided them into two parts randomly, and treat them by the Carpometacarpal direct approach solution and dual wrist palmar surgical approach solution respectively. After the surgery, the differences in the incidence of median nerve irritation are significant (P < 0.01). With reference to the exposure time of fracture, the operation time and the pronator quadratus muscle repair rate, we find that the exposure time of fracture and the operation time in the dual wrist palmar surgical approach solution are much less than that as compared to the Carpometacarpal direct approach solution (P < 0.01). The improved dual wrist palmar surgical approach can lead to a successful treatment of the distal radius fractures volar distal radial ulnar by reducing the blind exposure problem. As such, the surgeon can complete treatment of fractures of the region under direct vision during operation. Furthermore, reducing the median nerve in the carpal tunnel and the structure of the stretch can decrease the incidence of postoperative complications. Postoperative X-ray diagnosis is then performed to examine the patients' recovery and assist in clinical follow-up. Our study proves that the volar wrist dual channel approach can be successfully achieved by a surface incision surgical implementation of the dual channel, and gives rise to a minimally invasive operation.


Asunto(s)
Fijación Interna de Fracturas/métodos , Fracturas del Radio/diagnóstico por imagen , Fracturas del Radio/cirugía , Fracturas del Cúbito/diagnóstico por imagen , Fracturas del Cúbito/cirugía , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Periodo Posoperatorio , Radiografía , Adulto Joven
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...