Application of Fiber Ring for Protection of Passive Optical Infrastructure

Today, passive optical networks (PONs) are mostly used as modern high-speed access networks for various applications. However, there are also several specific applications, such as in business, office, army or science sector, which require a complex protection and backup system against failures and malfunctions. Typically, tree or star topologies are used for passive optical networks PONs. These topologies are vulnerable mainly against the failures of central optical line termination (OLT) unit. This paper presents an innovative method for protecting PONs by using ring topologies, especially the OLT unit. The method is described in the article, and an elementary mathematical model for calculations of asymmetric passive optical splitters together with an example is included as well

Modeling of Transmission Functions and Crosstalk in Metallic Cables for Implementation of MIMO Concept

The new promising wireless networks based on multi-carrier modulations (MCM) and multiple-input multiple-output concept (MIMO) will soon offer high-speed digital connections. Their access points are mostly connected by fixed metallic lines to core data and telecommunication networks. That is why it will also be necessary to increase the transmission speed and overall performance of these fixed access networks adequately in order to meet the expected requirements of wireless connections. It would be possible to use VDSL2 digital subscriber lines and implement MIMO concept into the existing metallic networks for this purpose, but before that it will be necessary to solve several problems first. The transmission capacity of present VDSL2 digital lines is limited mainly by crosstalk occurring in metallic cables. This paper describes a new method for modeling of transmission functions and crosstalk in multi-pair and multi-quad metallic cables including its mathematical implementation, and it also gives an example of results obtained so far. The presented model is based on statistical evaluations of measured values, generation of pseudo-random components of frequency response and subsequent filtration process

Variation in use of surveillance colonoscopy among colorectal cancer survivors in the United States

<p>Abstract</p> <p>Background</p> <p>Clinical practice guidelines recommend colonoscopies at regular intervals for colorectal cancer (CRC) survivors. Using data from a large, multi-regional, population-based cohort, we describe the rate of surveillance colonoscopy and its association with geographic, sociodemographic, clinical, and health services characteristics.</p> <p>Methods</p> <p>We studied CRC survivors enrolled in the Cancer Care Outcomes Research and Surveillance (CanCORS) study. Eligible survivors were diagnosed between 2003 and 2005, had curative surgery for CRC, and were alive without recurrences 14 months after surgery with curative intent. Data came from patient interviews and medical record abstraction. We used a multivariate logit model to identify predictors of colonoscopy use.</p> <p>Results</p> <p>Despite guidelines recommending surveillance, only 49% of the 1423 eligible survivors received a colonoscopy within 14 months after surgery. We observed large regional differences (38% to 57%) across regions. Survivors who received screening colonoscopy were more likely to: have colon cancer than rectal cancer (OR = 1.41, 95% CI: 1.05-1.90); have visited a primary care physician (OR = 1.44, 95% CI: 1.14-1.82); and received adjuvant chemotherapy (OR = 1.75, 95% CI: 1.27-2.41). Compared to survivors with no comorbidities, survivors with moderate or severe comorbidities were less likely to receive surveillance colonoscopy (OR = 0.69, 95% CI: 0.49-0.98 and OR = 0.44, 95% CI: 0.29-0.66, respectively).</p> <p>Conclusions</p> <p>Despite guidelines, more than half of CRC survivors did not receive surveillance colonoscopy within 14 months of surgery, with substantial variation by site of care. The association of primary care visits and adjuvant chemotherapy use suggests that access to care following surgery affects cancer surveillance.</p

Factors associated with adherence to chemotherapy guidelines in patients with non-small cell lung cancer

Evidence-based guidelines recommend chemotherapy for medically fit patients with stage II–IV non-small cell lung cancer (NSCLC). Adherence to chemotherapy guidelines has rarely been studied among large populations, mainly because performance status (PS), a key component in assessing chemotherapy appropriateness, is missing from claims-based datasets. Among a large cohort of patients with known PS, we describe first line chemotherapy use relative to guideline recommendations and identify patient factors associated with guideline concordant use

Survival among non-small cell lung cancer patients with poor performance status after first line chemotherapy

Performance status (PS) is a commonly used factor in determining the appropriateness for chemotherapy of patients with non-small cell lung cancer (NSCLC). The prevalence of poor PS and impact of chemotherapy on survival among NSCLC patients has not been studied in community populations

A personalized Uncertainty Quantification framework for patient survival models: estimating individual uncertainty of patients with metastatic brain tumors in the absence of ground truth

TodevelopanovelUncertaintyQuantification (UQ) framework to estimate the uncertainty of patient survival models in the absence of ground truth, we developed and evaluated our approach based on a dataset of 1383 patients treated with stereotactic radiosurgery (SRS) for brain metastases between January 2015 and December 2020. Our motivating hypothesis is that a time-to-event prediction of a test patient on inference is more certain given a higher feature-space-similarity to patients in the training set. Therefore, the uncertainty for a particular patient-of-interest is represented by the concordance index between a patient similarity rank and a prediction similarity rank. Model uncertainty was defined as the increased percentage of the max uncertainty-constrained-AUC compared to the model AUC. We evaluated our method on multiple clinically-relevant endpoints, including time to intracranial progression (ICP), progression-free survival (PFS) after SRS, overall survival (OS), and time to ICP and/or death (ICPD), on a variety of both statistical and non-statistical models, including CoxPH, conditional survival forest (CSF), and neural multi-task linear regression (NMTLR). Our results show that all models had the lowest uncertainty on ICP (2.21%) and the highest uncertainty (17.28%) on ICPD. OS models demonstrated high variation in uncertainty performance, where NMTLR had the lowest uncertainty(1.96%)and CSF had the highest uncertainty (14.29%). In conclusion, our method can estimate the uncertainty of individual patient survival modeling results. As expected, our data empirically demonstrate that as model uncertainty measured via our technique increases, the similarity between a feature-space and its predicted outcome decreases

Cálculo de la performance de los paneles solares de un módulo propulsor para microsatélites

En el marco del estudio de factibilidad de un módulo propulsor para microsatélites, se efectuó el cálculo de la performance de los paneles solares que lo equipan, con el objetivo de averiguar si producen energía eléctrica suficiente para presurizar el combustible del motor del módulo (motor cohete híbrido inverso). La metodología propuesta incluye la simulación en órbita de las radiaciones exteriores más importantes y el cómputo de los flujos térmicos y las potencias eléctricas disponibles; esto sobre una de las órbitas LEO del lanzador Titan III y para distintos perfiles de vuelo. Como resultados tenemos las funciones flujo térmico – tiempo, potencia eléctrica disponible – tiempo y el valor de la energía eléctrica generada para cada perfil de vuelo. Se concluye, para todos los perfiles de vuelo, que es factible realizar la presurización del combustible mediante el sistema propuesto.For the feasibility study of a microsatellite propulsion module equiped with an inverse hybrid rocket motor, performance of its solar panels was calculated. Main goal is to be sure that available in orbit solar energy colected by the panels is enought to pressurize the fuel for the rocket motor operation. Methodology for this work consists in fly simulation of microsatellite lanched by Titan III; in orbit radiation on satellite panel calculation taking into account different fly profiles; in-orbit radiation flows calculation; time history of available electrical power definition and integration for comparison with required enthalpy for fuel pressurization. Main conclusion is the feasibility of a solar powered fuel feed system, for a small inverse hybrid rocket motor for microsatellite propulsive module.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Presurización en órbita del combustible de un motor híbrido para microsatélite mediante energía solar

Para el estudio de factibilidad del uso de propulsión híbrida inversa en microsatélites, se implementó un modelo matemático de presurización de combustible, utilizando energía solar. El objetivo del trabajo fue calcular las órbitas necesarias para presurizar el combustible e investigar parámetros de diseño. La metodología consistió en la elaboración de un modelo matemático de un sistema de presurización de combustible líquido, mediante energía solar. Luego se confeccionaron curvas de vaporización para el n-butano. Usando estos elementos, y el estudio de energía disponible para una órbita seleccionada, contemplando distintos perfiles de vuelo, se efectuó el cálculo de órbitas necesarias para su correcto funcionamiento. Se obtuvieron resultados para un rendimiento del sub-sistema de calefactores de 0,6. Se presenta el esquema del sistema de presurización y los resultados parametrizados de los cálculos. Se concluyó que este sistema es sencillo, confiable y se adapta a pequeños motores.For the study of feasibility on the use of hybrid inverse propulsion for microsatellites, a mathematical model of pressurization of fuel in orbit using solar power was formulated. The main goal of this work is to estimate the number of orbits needed for to pressurize the fuel, considering realistic conditions. The methodology consists in formulating a parametric mathematical model of steam production system using solar energy. A fuel vaporization model was implemented. Taking into account the available energy in orbit and the different fly profiles sun results, were obtained and discused, arriving to the main conclusion which indicates the factibility of this pressurization system. Details of the thermal mathematical model, and the fuel feed system for this hybrid motor are presented with the parametric results of the calculation. It was concluded that this system is simple and reliable and well adapted for small rocket motors.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Presurización en órbita del combustible de un motor híbrido para microsatélite mediante energía solar

Para el estudio de factibilidad del uso de propulsión híbrida inversa en microsatélites, se implementó un modelo matemático de presurización de combustible, utilizando energía solar. El objetivo del trabajo fue calcular las órbitas necesarias para presurizar el combustible e investigar parámetros de diseño. La metodología consistió en la elaboración de un modelo matemático de un sistema de presurización de combustible líquido, mediante energía solar. Luego se confeccionaron curvas de vaporización para el n-butano. Usando estos elementos, y el estudio de energía disponible para una órbita seleccionada, contemplando distintos perfiles de vuelo, se efectuó el cálculo de órbitas necesarias para su correcto funcionamiento. Se obtuvieron resultados para un rendimiento del sub-sistema de calefactores de 0,6. Se presenta el esquema del sistema de presurización y los resultados parametrizados de los cálculos. Se concluyó que este sistema es sencillo, confiable y se adapta a pequeños motores.For the study of feasibility on the use of hybrid inverse propulsion for microsatellites, a mathematical model of pressurization of fuel in orbit using solar power was formulated. The main goal of this work is to estimate the number of orbits needed for to pressurize the fuel, considering realistic conditions. The methodology consists in formulating a parametric mathematical model of steam production system using solar energy. A fuel vaporization model was implemented. Taking into account the available energy in orbit and the different fly profiles sun results, were obtained and discused, arriving to the main conclusion which indicates the factibility of this pressurization system. Details of the thermal mathematical model, and the fuel feed system for this hybrid motor are presented with the parametric results of the calculation. It was concluded that this system is simple and reliable and well adapted for small rocket motors.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Cálculo de la performance de los paneles solares de un módulo propulsor para microsatélites

En el marco del estudio de factibilidad de un módulo propulsor para microsatélites, se efectuó el cálculo de la performance de los paneles solares que lo equipan, con el objetivo de averiguar si producen energía eléctrica suficiente para presurizar el combustible del motor del módulo (motor cohete híbrido inverso). La metodología propuesta incluye la simulación en órbita de las radiaciones exteriores más importantes y el cómputo de los flujos térmicos y las potencias eléctricas disponibles; esto sobre una de las órbitas LEO del lanzador Titan III y para distintos perfiles de vuelo. Como resultados tenemos las funciones flujo térmico – tiempo, potencia eléctrica disponible – tiempo y el valor de la energía eléctrica generada para cada perfil de vuelo. Se concluye, para todos los perfiles de vuelo, que es factible realizar la presurización del combustible mediante el sistema propuesto.For the feasibility study of a microsatellite propulsion module equiped with an inverse hybrid rocket motor, performance of its solar panels was calculated. Main goal is to be sure that available in orbit solar energy colected by the panels is enought to pressurize the fuel for the rocket motor operation. Methodology for this work consists in fly simulation of microsatellite lanched by Titan III; in orbit radiation on satellite panel calculation taking into account different fly profiles; in-orbit radiation flows calculation; time history of available electrical power definition and integration for comparison with required enthalpy for fuel pressurization. Main conclusion is the feasibility of a solar powered fuel feed system, for a small inverse hybrid rocket motor for microsatellite propulsive module.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES