Analytical prediction of the spin stabilized satellite's attitude using the solar radiation torque

The aim of this paper is to present an analytical solution for the spin motion equations of spin-stabilized satellite considering only the influence of solar radiation torque. The theory uses a cylindrical satellite on a circular orbit and considers that the satellite is always illuminated. The average components of this torque were determined over an orbital period. These components are substituted in the spin motion equations in order to get an analytical solution for the right ascension and declination of the satellite spin axis. The time evolution for the pointing deviation of the spin axis was also analyzed. These solutions were numerically implemented and compared with real data of the Brazilian Satellite of Data Collection - SCD1 an SCD2. The results show that the theory has consistency and can be applied to predict the spin motion of spin-stabilized artificial satellites.

Perception and Attitude About Systemic Health and Periodontal Disease Among Dentistry Undergraduates

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Adaptação transcultural do formulário POLST: Physician Orders for Life-Sustaining Treatment

Pós-graduação em Saúde Coletiva - FMB

Association between education in EOL care and variability in EOL practice: a survey of ICU physicians

This study investigated the association between physician education in EOL and variability in EOL practice, as well as the differences between beliefs and practices regarding EOL in the ICU. Physicians from 11 ICUs at a university hospital completed a survey presenting a patient in a vegetative state with no family or advance directives. Questions addressed approaches to EOL care, as well physicians' personal, professional and EOL educational characteristics. The response rate was 89%, with 105 questionnaires analyzed. Mean age was 38 +/- A 8 years, with a mean of 14 +/- A 7 years since graduation. Physicians who did not apply do-not-resuscitate (DNR) orders were less likely to have attended EOL classes than those who applied written DNR orders [0/7 vs. 31/47, OR = 0.549 (0.356-0.848), P = 0.001]. Physicians who involved nurses in the decision-making process were more likely to be ICU specialists [17/22 vs. 46/83, OR = 4.1959 (1.271-13.845), P = 0.013] than physicians who made such decisions among themselves or referred to ethical or judicial committees. Physicians who would apply "full code" had less often read about EOL [3/22 vs. 11/20, OR = 0.0939 (0.012-0.710), P = 0.012] and had less interest in discussing EOL [17/22 vs. 20/20, OR = 0.210 (0.122-0.361), P < 0.001], than physicians who would withdraw life-sustaining therapies. Forty-four percent of respondents would not do what they believed was best for their patient, with 98% of them believing a less aggressive attitude preferable. Legal concerns were the leading cause for this dichotomy. Physician education about EOL is associated with variability in EOL decisions in the ICU. Moreover, actual practice may differ from what physicians believe is best for the patient.

US Food and Drug Administration approval of generic versions of complex biologics: implications for the practicing physician using low molecular weight heparins

Low-molecular-weight heparins (LMWHs) have shown equivalent or superior efficacy and safety to unfractionated heparin as antithrombotic therapy for patients with acute coronary syndromes. Each approved LMWH is a pleotropic biological agent with a unique chemical, biochemical, biophysical and biological profile and displays different pharmacodynamic and pharmacokinetic profiles. As a result, LMWHs are neither equipotent in preclinical assays nor equivalent in terms of their clinical efficacy and safety. Previously, the US Food and Drug Administration (FDA) cautioned against using various LMWHs interchangeably, however recently, the FDA approved generic versions of LMWH that have not been tested in large clinical trials. This paper highlights the bio-chemical and pharmacological differences between the LMWH preparations that may result in different clinical outcomes, and also reviews the implications and challenges physicians face when generic versions of the original/innovator agents are approved for clinical use.

Fault detection, diagnosis and active fault tolerant control for a satellite attitude control system

Modern control systems are becoming more and more complex and control algorithms more and more sophisticated. Consequently, Fault Detection and Diagnosis (FDD) and Fault Tolerant Control (FTC) have gained central importance over the past decades, due to the increasing requirements of availability, cost efficiency, reliability and operating safety. This thesis deals with the FDD and FTC problems in a spacecraft Attitude Determination and Control System (ADCS). Firstly, the detailed nonlinear models of the spacecraft attitude dynamics and kinematics are described, along with the dynamic models of the actuators and main external disturbance sources. The considered ADCS is composed of an array of four redundant reaction wheels. A set of sensors provides satellite angular velocity, attitude and flywheel spin rate information. Then, general overviews of the Fault Detection and Isolation (FDI), Fault Estimation (FE) and Fault Tolerant Control (FTC) problems are presented, and the design and implementation of a novel diagnosis system is described. The system consists of a FDI module composed of properly organized model-based residual filters, exploiting the available input and output information for the detection and localization of an occurred fault. A proper fault mapping procedure and the nonlinear geometric approach are exploited to design residual filters explicitly decoupled from the external aerodynamic disturbance and sensitive to specific sets of faults. The subsequent use of suitable adaptive FE algorithms, based on the exploitation of radial basis function neural networks, allows to obtain accurate fault estimations. Finally, this estimation is actively exploited in a FTC scheme to achieve a suitable fault accommodation and guarantee the desired control performances. A standard sliding mode controller is implemented for attitude stabilization and control. Several simulation results are given to highlight the performances of the overall designed system in case of different types of faults affecting the ADCS actuators and sensors.

Magnetic actuators for nanosatellite attitude control

The research and the activities presented in the following thesis report have been led at the California Polytechnic State University (US) under the supervision of Prof. Jordi Puig Suari. The objective of the research has been the study of magnetic actuators for nanosatellite attitude control, called magnetorquer. Theese actuators are generally divided in three different kinds: air core torquer, embedded coil and torquerod. In a first phase of the activity, each technology has been analyzed, defining advantages and disadvantages, determining manufacturing procedures and creating mathematical model and designing equation. Dimensioning tools have been then implemented in numerical software to create an instrument that permits to determine the optimal configuration for defined requirements and constraints. In a second phase of the activities the models created have been validated exploiting prototypes and proper instruments for measurements. The instruments and the material exploited for experiments and prototyping have been provided by the PolySat and CubeSat laboratories. The results obtained led to the definition of a complete designing tool and procedure for nanosatellite magnetic actuators, introducing a cost analysis for each kind of solution. The models and the tools have been maintained fully parametric in order to offer a universal re-scalable instrument for satellite of different dimension class.

Physician speciality and pain reduction in patients with depressive symptoms under treatment with venlafaxine

Excessive pain perception may lead to unnecessary diagnostic testing or invasive procedures resulting in iatrogenic complications and prolonged disability. Naturalistic studies on patients with chronic pain and depressive symptoms investigating the impact of medical speciality on treatment outcome in a primary care setting are lacking.