Algunos aspectos dinámicos en un modelo bioeconómico

Se estudian en este trabajo algunos aspectos relevantes de la teoría de Sistemas Dinámicos aplicados a un modelo de competición interespecies. Se trata de un estudio cualitativo en el cual, en función de los parámetros del sistema, se analizan los cambios en el número y/o estabilidad de los puntos de equilibrio del sistema. Todo ello con el objetivo de establecer los tipos de bifurcaciones que pueden presentarse en el modelo

Análisis de la estabilidad y de bifurcaciones en un modelo dinámico aplicado a la gestión de una pesquería

Estudiamos en esta comunicación la estabilidad de las soluciones de equilibrio del sistema dinámico resultante de aplicar el Principio del Máximo de Pontryagin a un modelo de control óptimo para la gestión de una pesquería. Veremos cómo puede hablarse en un modelo de este tipo de la estabilidad condicional del punto de silla. Considerando la tasa de descuento social como parámetro del sistema, se analizan las bifurcaciones locales de codimensión uno, es decir, los cambios en la estabilidad de los equilibrios y/o la aparición de nuevos equilibrios u órbitas cerradas al considerar pequeñas variaciones de dicho parámetro. En este contexto, usamos el Teorema de Bifurcación de Hopf para establecer la existencia, bajo determinadas hipótesis, de trayectorias oscilatorias de tipo ciclo límit

Bifurcaciones de Hopf y ciclos límites en un modelo de control óptimo aplicado a la pesquería de chamelea gallina del litoral Suratlántico español

Este trabajo pretende ampliar el presentado en el IV Encuentro de Economía Aplicada (Reus, 2001) que, bajo el título Análisis de la estabilidad y de bifurcaciones en un modelo dinámico aplicado a la gestión de una pesquería, presentaba un modelo de control óptimo caracterizado por la tradicional presencia de un punto de silla y por la existencia de trayectorias cerradas de tipo ciclo límite para los valores de la tasa de descuento social que verificaran las hipótesis del teorema de bifurcación de Hopf. La aplicación de los resultados obtenidos a nivel teórico al caso de la pesquería de chamelea gallina de la región Suratlántica Española evidenció que tales trayectorias cerradas aparecían en un entorno de un equilibrio estacionario no factible en un caso real, pues el correspondiente nivel de biomasa era negativo. Dada la evolución histórica de la citada pesquería, se ha considerado la situación de la misma en la década de los años 60, a principios de la cual existían unos stocks de chirla apenas explotados, lo que nos ha llevado a formular el mismo problema de control empleando una tasa de capturas distinta de la habitual del modelo de Schaefer que habíamos usado en el primer trabajo. Mediante la aplicación del teorema de bifurcación de Hopf se establece así la presencia de ciclos límites en el sistema dinámico resultante de aplicar el principio del máximo de Pontryagin a este nuevo problema de contro

Correlational analysis and predictive validity of psychological constructs related with pain in fibromyalgia

<p>Abstract</p> <p>Background</p> <p>Fibromyalgia (FM) is a prevalent and disabling disorder characterized by a history of widespread pain for at least three months. Pain is considered a complex experience in which affective and cognitive aspects are crucial for prognosis. The aim of this study is to assess the importance of pain-related psychological constructs on function and pain in patients with FM.</p> <p>Methods</p> <p>Design</p> <p>Multicentric, naturalistic, one-year follow-up study.</p> <p><it>Setting and study sample</it>. Patients will be recruited from primary care health centres in the region of Aragon, Spain. Patients considered for inclusion are those aged 18-65 years, able to understand Spanish, who fulfil criteria for primary FM according to the American College of Rheumatology, with no previous psychological treatment.</p> <p>Measurements</p> <p>The variables measured will be the following: main variables (pain assessed with a visual analogue scale and with sphygmomanometer and general function assessed with Fibromyalgia Impact Questionnaire, and), psychological constructs (pain catastrophizing, pain acceptance, mental defeat, psychological inflexibility, perceived injustice, mindfulness, and positive and negative affect), and secondary variables (sociodemographic variables, anxiety and depression assessed with Hospital Anxiety and Depression Scale, and psychiatric interview assessed with MINI). Assessments will be carried at baseline and at one-year follow-up.</p> <p>Main outcome</p> <p>Pain Visual Analogue Scale.</p> <p>Analysis</p> <p>The existence of differences in socio-demographic, main outcome and other variables regarding pain-related psychological constructs will be analysed using Chi Square test for qualitative variables, or Student <it>t </it>test or variance analysis, respectively, for variables fulfilling the normality hypothesis. To assess the predictive value of pain-related psychological construct on main outcome variables at one-year follow-up, use will be made of a logistic regression analysis adjusted for socio-demographic and clinical variables. A Spearman Rho non-parametric correlation matrix will be developed to determine possible overlapping between pain-related psychological constructs.</p> <p>Discussion</p> <p>In recent years, the relevance of cognitive and affective aspects for the treatment of chronic pain, not only in FM but also in other chronic pain diseases, has been widely acknowledged. However, the relative importance of these psychological constructs, the relationship and possible overlapping between them, or the exact meaning of them in pain are not enough known.</p

Effectiveness of the psychological and pharmacological treatment of catastrophization in patients with fibromyalgia: a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Fibromyalgia is a prevalent and disabling disorder characterized by widespread pain and other symptoms such as insomnia, fatigue or depression. Catastrophization is considered a key clinical symptom in fibromyalgia; however, there are no studies on the pharmacological or psychological treatment of catastrophizing. The general aim of this study is to assess the effectiveness of cognitive-behaviour therapy and recommended pharmacological treatment for fibromyalgia (pregabalin, with duloxetine added where there is a comorbid depression), compared with usual treatment at primary care level.</p> <p>Method/design</p> <p><it>Design</it>: A multi-centre, randomized controlled trial involving three groups: the control group, consisting of usual treatment at primary care level, and two intervention groups, one consisting of cognitive-behaviour therapy, and the other consisting of the recommended pharmacological treatment for fibromyalgia.</p> <p><it>Setting</it>: 29 primary care health centres in the city of Zaragoza, Spain.</p> <p><it>Sample</it>: 180 patients, aged 18–65 years, able to understand and read Spanish, who fulfil criteria for primary fibromyalgia, with no previous psychological treatment, and no pharmacological treatment or their acceptance to discontinue it two weeks before the onset of the study.</p> <p><it>Intervention</it>: Psychological treatment is based on the manualized protocol developed by Prof. Escobar et al, from the University of New Jersey, for the treatment of somatoform disorders, which has been adapted by our group for the treatment of fibromyalgia. It includes 10 weekly sessions of cognitive-behaviour therapy. Pharmacological therapy consists of the recommended pharmacological treatment for fibromyalgia: pregabalin (300–600 mg/day), with duloxetine (60–120 mg/day) added where there is a comorbid depression).</p> <p><it>Measurements</it>: The following socio-demographic data will be collected: sex, age, marital status, education, occupation and social class. The diagnosis of psychiatric disorders will be made with the Structured Polyvalent Psychiatric Interview. Other instruments to be administered are the Pain Catastrophizing Scale, the Hamilton tests for Anxiety and for Depression, the Fibromyalgia Impact Questionnaire (FIQ), the EuroQuol-5 domains (EQ-5D), and the use of health and social services (CSRI). Assessments will be carried out at baseline, 1, 3, and 6 months.</p> <p><it>Main variable</it>: Pain catastrophizing.</p> <p><it>Analysis</it>: The analysis will be per intent to treat. We will use the general linear models of the SPSS version 15 statistical package, to analyse the effect of the treatment on the result variable (pain catastrophizing).</p> <p>Discussion</p> <p>It is necessary to assess the effectiveness of pharmacological and psychological treatments for pain catastrophizing in fibromyalgia. This randomized clinical trial will determine whether both treatments are effective for this important prognostic variable in patients with fibromyalgia.</p> <p>Trial registration</p> <p>Current Controlled Trials ISRCTN10804772</p

Radiation and Dust Sensor for Mars Environmental Dynamic Analyzer Onboard M2020 Rover

32 pags., 26 figs., 3 tabs. -- This article belongs to the Section Remote SensorsThe Radiation and Dust Sensor is one of six sensors of the Mars Environmental Dynamics Analyzer onboard the Perseverance rover from the Mars 2020 NASA mission. Its primary goal is to characterize the airbone dust in the Mars atmosphere, inferring its concentration, shape and optical properties. Thanks to its geometry, the sensor will be capable of studying dust-lifting processes with a high temporal resolution and high spatial coverage. Thanks to its multiwavelength design, it will characterize the solar spectrum from Mars' surface. The present work describes the sensor design from the scientific and technical requirements, the qualification processes to demonstrate its endurance on Mars' surface, the calibration activities to demonstrate its performance, and its validation campaign in a representative Mars analog. As a result of this process, we obtained a very compact sensor, fully digital, with a mass below 1 kg and exceptional power consumption and data budget features.This work has been funded with the help of the Spanish National Research, Development and Innovation Program, through the grants RTI2018-099825-B-C31, ESP2016-80320-C2-1-R and ESP2014-54256-C4-3-R. DT acknowledges the financial support from the Comunidad de Madrid for an “Atracción de Talento Investigador” grant (2018-T2/TIC10500). ASL is supported by Grant PID2019-109467GB-I00 funded by MCIN/AEI/10.13039/501100011033/ and by Grupos Gobierno Vasco IT1366-19. The US co-authors performed their work under sponsorship from NASA’s Mars 2020 project, from the Game Changing Development program within the Space Technology Mission Directorate, and from the Human Exploration and Operations Directorate.Peer reviewe

Magnetic equilibrium design for the SMART tokamak

Article number 112706The SMall Aspect Ratio Tokamak (SMART) device is a new compact (plasma major radius Rgeo≥0.40 m, minor radius a≥0.20 m, aspect ratio A≥1.7) spherical tokamak, currently in development at the University of Seville. The SMART device has been designed to achieve a magnetic field at the plasma center of up to Bϕ=1.0 T with plasma currents up to Ip=500 kA and a pulse length up to τft=500 ms. A wide range of plasma shaping configurations are envisaged, including triangularities between −0.50≤δ≤0.50 and elongations of κ≤2.25. Control of plasma shaping is achieved through four axially variable poloidal field coils (PF), and four fixed divertor (Div) coils, nominally allowing operation in lower-single null, upper-single null and double-null configurations. This work examines phase 2 of the SMART device, presenting a baseline reference equilibrium and two highly-shaped triangular equilibria. The relevant PF and Div coil current waveforms are also presented. Equilibria are obtained via an axisymmetric Grad-Shafranov force balance solver (Fiesta), in combination with a circuit equation rigid current displacement model (RZIp) to obtain time-resolved vessel and plasma currents.Feder (UE) US-15570Feder (UE) IE17-5670Horizonte 2020 (Unión Europea) 80516

Impact of renin-angiotensin system inhibitors on clinical outcomes and ventricular remodelling after transcatheter aortic valve implantation: rationale and design of the RASTAVI randomised multicentre study.

Transcatheter aortic valve implantation (TAVI) as a treatment in severe aortic stenosis (AS) is an excellent alternative to conventional surgical replacement. However, long-term outcomes are not benign. Renin-angiotensin system (RAS) blockade has shown benefit in terms of adverse remodelling in severe AS and after surgical replacement. The RAS blockade after TAVI (RASTAVI) trial aims to detect if there is a benefit in clinical outcomes and ventricular remodelling with this therapeutic strategy following the TAVI procedure. The study has been designed as a randomised 1:1 open-label study that will be undertaken in 8 centres including 336 TAVI recipients. All patients will receive the standard treatment. The active treatment group will receive ramipril as well. Randomisation will be done before discharge, after signing informed consent. All patients will be followed up for 3 years. A cardiac magnetic resonance will be performed initially and at 1 year to assess ventricular remodelling, defined as ventricular dimensions, ejection fraction, ventricular mass and fibrosis. Recorded events will include cardiac death, admission due to heart failure and stroke. The RASTAVI Study will improve the management of patients after TAVI and may help to increase their quality of life, reduce readmissions and improve long-term survival in this scenario. All authors and local ethics committees have approved the study design. All patients will provide informed consent. Results will be published irrespective of whether the findings are positive or negative. NCT03201185

Predicting critical illness on initial diagnosis of COVID-19 based on easily obtained clinical variables: development and validation of the PRIORITY model

Objectives: We aimed to develop and validate a prediction model, based on clinical history and examination findings on initial diagnosis of coronavirus disease 2019 (COVID-19), to identify patients at risk of critical outcomes. Methods: We used data from the SEMI-COVID-19 Registry, a cohort of consecutive patients hospitalized for COVID-19 from 132 centres in Spain (23rd March to 21st May 2020). For the development cohort, tertiary referral hospitals were selected, while the validation cohort included smaller hospitals. The primary outcome was a composite of in-hospital death, mechanical ventilation, or admission to intensive care unit. Clinical signs and symptoms, demographics, and medical history ascertained at presentation were screened using least absolute shrinkage and selection operator, and logistic regression was used to construct the predictive model. Results: There were 10 433 patients, 7850 in the development cohort (primary outcome 25.1%, 1967/7850) and 2583 in the validation cohort (outcome 27.0%, 698/2583). The PRIORITY model included: age, dependency, cardiovascular disease, chronic kidney disease, dyspnoea, tachypnoea, confusion, systolic blood pressure, and SpO2 ≤93% or oxygen requirement. The model showed high discrimination for critical illness in both the development (C-statistic 0.823; 95% confidence interval (CI) 0.813, 0.834) and validation (C-statistic 0.794; 95%CI 0.775, 0.813) cohorts. A freely available web-based calculator was developed based on this model (https://www.evidencio.com/models/show/2344). Conclusions: The PRIORITY model, based on easily obtained clinical information, had good discrimination and generalizability for identifying COVID-19 patients at risk of critical outcomes

Expectations, experiences and attitudes of patients and primary care health professionals regarding online psychotherapeutic interventions for depression: protocol for a qualitative study

BACKGROUND: In the year 2020, depression will cause the second highest amount of disability worldwide. One quarter of the population will suffer from depression symptoms at some point in their lives. Mental health services in Western countries are overburdened. Therefore, cost-effective interventions that do not involve mental health services, such as online psychotherapy programs, have been proposed. These programs demonstrate satisfactory outcomes, but the completion rate for patients is low. Health professionals' attitudes towards this type of psychotherapy are more negative than the attitudes of depressed patients themselves. The aim of this study is to describe the profile of depressed patients who would benefit most from online psychotherapy and to identify expectations, experiences, and attitudes about online psychotherapy among both patients and health professionals that can facilitate or hinder its effects. METHODS: A parallel qualitative design will be used in a randomised controlled trial on the efficiency of online psychotherapeutic treatment for depression. Through interviews and focus groups, the experiences of treated patients, their reasons for abandoning the program, the expectations of untreated patients, and the attitudes of health professionals will be examined. Questions will be asked about training in new technologies, opinions of online psychotherapy, adjustment to therapy within the daily routine, the virtual and anonymous relationship with the therapist, the process of online communication, information necessary to make progress in therapy, process of working with the program, motivations and attitudes about treatment, expected consequences, normalisation of this type of therapy in primary care, changes in the physician-patient relationship, and resources and risks. A thematic content analysis from the grounded theory for interviews and an analysis of the discursive positions of participants based on the sociological model for focus groups will be performed. DISCUSSION: Knowledge of the expectations, experiences, and attitudes of both patients and medical personnel regarding online interventions for depression can facilitate the implementation of this new psychotherapeutic tool. This qualitative investigation will provide thorough knowledge of the perceptions, beliefs, and values of patients and clinicians, which will be very useful for understanding how to implement this intervention method for depression