Pediatric thyroid nodules: predictors of malignancy

Introducción: La caracterización de los nódulos tiroideos en pediatría no ha sido aún bien comunicada. El riesgo de malignidad es mayor que en adultos por lo que requieren una evaluación exhaustiva. Objetivo: caracterizar una cohorte de pacientes pediátricos con nódulos tiroideos e identificar predictores de malignidad. Pacientes y métodos: se analizaron los hallazgos demográficos, clínicos, bioquímicos, ecográficos y citológicos de una cohorte prospectiva de 106 pacientes 2,5mU/l, nódulo sólido, márgenes irregulares, microcalcificaciones y adenopatías cervicales patológicas. Un resultado citológico Bethesda V/VI tuvo un valor predictivo (VP) positivo de 87,5% y VP negativo de 96,4%. Conclusiones: El nódulo tiroideo en pediatría es más frecuentemente maligno. La evaluación sistemática permitió identificar ciertos hallazgos clínicos, bioquímicos, ecográficos y citológicos predictores de malignidad que deben ser considerados al decidir el enfoque diagnóstico.Introduction: Published data on pediatric thyroid nodule´s characterization is scarce. With higher risk of malignancy than in adults, they require an exhaustive diagnostic work-up. Objective: To characterize a pediatric cohort with thyroid nodules to identify predictors of malignancy. Patients and methods: Demographic, clinical, biochemical, ultrasonographical and cytological data were analyzed prospectively in 106 patients 2.5mU/l, solid nodules, irregular margins, microcalcifications and pathologic adenopathies. Cytological results Bethesda V/VI showed positive and negative predictive values of 87.5% and 96.4% respectively. Conclusions: Pediatric thyroid nodules are more frequently malignant. The systematic evaluation of our cohort allowed the identification of clinical, biochemical ultrasonographical and cytological predictors of malignancy that have to be considered when deciding the diagnostic approach.Fil: Papendieck, Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Gobierno de la Ciudad de Buenos Aires. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Fundación de Endocrinología Infantil. Centro de Investigaciones Endocrinológicas "Dr. César Bergada"; ArgentinaFil: Venara, Marcela Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Gobierno de la Ciudad de Buenos Aires. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Fundación de Endocrinología Infantil. Centro de Investigaciones Endocrinológicas "Dr. César Bergada"; ArgentinaFil: Elias, Eugenia. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Cozzani, Hugo. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Mateos, Fernanda. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez";; ArgentinaFil: Maglio, Silvana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Calcagno, María Luján. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Gruñeiro Papendieck, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Gobierno de la Ciudad de Buenos Aires. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Fundación de Endocrinología Infantil. Centro de Investigaciones Endocrinológicas "Dr. César Bergada"; ArgentinaFil: Bergadá, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Gobierno de la Ciudad de Buenos Aires. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Fundación de Endocrinología Infantil. Centro de Investigaciones Endocrinológicas "Dr. César Bergada"; ArgentinaFil: Chiesa, Ana Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Gobierno de la Ciudad de Buenos Aires. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Fundación de Endocrinología Infantil. Centro de Investigaciones Endocrinológicas "Dr. César Bergada"; Argentin

Investigaciones en ciencias humanas y sociales : del ABC disciplinar a la reflexión metodológica

Diversidad de objetos, variedad de enfoques, prácticas disciplinares y multidisciplinares, y ejemplos de ejecución de proyectos de investigación y desarrollo son los rasgos distintivos de los siete capítulos que integran esta obra. En ellos se recoge el material desplegado en los Seminarios-Talleres de Metodología de la Investigación en Humanidades que se realizaron en el marco de las V Jornadas de Investigación de la Facultad de Filosofía y Letras de la Universidad Nacional de Cuyo en setiembre de 2004: estudios sobre procesos sociales, cuestiones educativas, geográficas, históricas, lingüísticas y literarias. Algunos capítulos han mantenido el estilo y formato característicos del contexto de los seminarios-talleres, a veces con ligeras modificaciones; otros han sido enteramente reescritos para la convocatoria de esta publicación. Este libro refleja entonces abordajes disciplinares y pluridisciplinares diversos a problemáticas igualmente variadas. Por tratarse de propuestas orientadas a y/o basadas en seminarios-talleres, está claro que los autores involucrados no pueden abarcar todos los aspectos de los objetos de estudio respectivos. Sin embargo, la idea es al menos brindar algún punto de vista sobre el estadio de desarrollo de algunas de las investigaciones actualmente en ejecución en nuestra Facultad

In situ evidence of firehose instability in multiple magnetic reconnection

International audience<p>Energy conversion via reconnecting current sheets is common in space and astrophysical plasma. Frequently, current sheets disrupt at multiple reconnection sites, leading to the formation of plasmoid structures between the sites, which might affect energy conversion. We present in situ observations of multiple reconnection in the Earth’s magnetotail. The observed highly accelerated proton beams parallel to magnetic field and the ion-scale wave-like fluctuations of the whistler type imply the development of firehose instability between two active reconnection sites. The linear wave dispersion relation estimated for the measured plasma parameters, indicates a positive growth rate of the firehose-related electromagnetic fluctuations. The detailed time-space evolution of the plasmoid is obtained by reconstruction of observations with the 2.5D implicit particle-in-cell simulations. In course of time, plasma on the periphery of the plasmoid becomes anisotropic and as it overcomes the firehose marginal stability threshold, the corresponding magnetic field fluctuations arise. The results of observations and simulations suggest that the firehose instability operating between reconnection sites, converts plasma energy of the proton temperature anisotropy to the energy of magnetic field fluctuations, counteracting with the conversion of magnetic energy to the energy of plasma in reconnection sites.</p&gt

Fire hose instability observed between the reconnection sites in the Earth's magnetotail

International audienc

La reconnexion magnétique vue par la mission MMS

International audienc

In situ evidence of firehose instability in multiple reconnection

Energy conversion via reconnecting current sheets is common in space and astrophysical plasmas. Frequently, current sheets disrupt at multiple reconnection sites, leading to the formation of plasmoid structures between sites, which might affect energy conversion. We present in situ evidence of the firehose instability in multiple reconnection in the Earth's magnetotail. The observed proton beams accelerated in the direction parallel to magnetic field and ion-scale fluctuations of whistler type imply the development of firehose instability between two active reconnection sites. The linear wave dispersion relation, estimated for the measured plasma parameters, indicates a positive growth rate of firehose-related electromagnetic fluctuations. Simulations of temporal evolution of the observed multiple reconnection by using a 2.5D implicit particle-in-cell code show that, as the plasmoid formed between two reconnection sites evolves, the plasma at its edge becomes anisotropic and overcomes the firehose marginal stability threshold, leading to the generation of magnetic field fluctuations. The combined results of observations and simulations suggest that the firehose instability, operating between reconnection sites, converts plasma kinetic energy into energy of magnetic field fluctuations, counteracting the conversion of magnetic energy into plasma energy occurring at reconnection sites. This suggests that magnetic energy conversion in multiple reconnection can be less efficient than in the case of the single-site reconnection

Evaluation of the generalized Ohm's law at the subsolar magnetopause diffusion region with MMS data

International audienceMagnetic reconnection is a fundamental process occurring in thin current sheets where a change in the magnetic field topology leads to fast magnetic energy conversion into energy of charged particles. A key yet poorly understood aspect is how the reconnection electric field is sustained in the diffusion region by the different terms in the generalized Ohm's law. In particular, the role of the pressure and inertia terms is not yet fully understood as well as the importance of the anomalous resistivity term and its source. Simulations have provided some estimations of the different terms; however direct observations have been scarce so far. The four-spacecraft Magnetospheric Multiscale Mission (NASA/MMS) allows, for the first time, the full evaluation of the generalized Ohm's law in the diffusion region. Here we present MMS observations at a few subsolar diffusion region crossings on October,3 rd 2015 where MMS spacecraft were separated by 25 km. We compare the measured electric field with the electric field due to both kinetic effects (electron pressure tensor, electron inertia terms) and to anomalous resistivity associated to different wave modes. The electric field is balanced by the Hall term at ion scales as expected. At smaller scales, preliminary results indicate that the electric field is mainly balanced by the divergence of the electron pressure tensor, although the contribution of anomalous resistivity is not negligible

Differentiated thyroid cancer in children:prevalence predictors in a large cohort with thyroid nodules followed prospectively

We retrospectively analyzed the findings of a prospective cohort of 75 children referred for thyroid nodules between2008 and 2013. Prevalence of papillary differentiated thyroid carcinoma was 18.7%. Thyrotropin >2.5 mIU/L, multinodulargoiter, solid nodules, irregular margins, and pathologic lymphadenopathies were identified as independent predictors of malignancyFil: Papendieck, Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas; ArgentinaFil: Gruñeiro, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas; ArgentinaFil: Venara, Marcela Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas; ArgentinaFil: Acha, Oscar. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutierrez"; ArgentinaFil: Cozzani, Hugo. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutierrez"; ArgentinaFil: Mateos, Fernando. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutierrez"; ArgentinaFil: Maglio, Silvana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutierrez"; ArgentinaFil: Calcagno, María Lujan. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Bergada, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas; ArgentinaFil: Chiesa, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas; Argentin

In situ spacecraft observations of structured electron diffusion regions during magnetic reconnection

International audience<p>Magnetic reconnection is a fundamental energy conversion process in plasmas. It occurs in thin current sheets, where a change in the magnetic field topology leads to rapid heating of plasma, plasma bulk acceleration and acceleration of plasma particles. To allow for magnetic field reconfiguration, both ions and electrons must be demagnetized. The ion and electron demagnetization  take place in the ion and electron diffusion regions respectively, in both cases at kinetic scales. For the first time, Magnetospheric Multiscale (MMS) spacecraft observations, at inter-spacecraft separation comparable to the electron inertial length, allow for a multi-point analysis of the electron diffusion region (EDR). A key question is whether the EDR has a homogeneous or patchy structure. </p><p>Here we report MMS observations at the magnetopause providing evidence of inhomogeneous current densities and energy conversion over a few (∼ 3 d<sub>e</sub>) electron inertial lengths suggesting that the EDR can be structured at electron scales. In particular, the energy conversion is patchy and changing sign in the vicinity of the reconnection site implying that the EDR comprises regions where energy is transferred from the field to the plasma and regions with the opposite energy transition, which is unexpected during reconnection. The origin of the patchy energy conversion appears to be connected to the large v<sub>e,N</sub> ∼ v<sub>e,M</sub> directed from the magnetosphere to magnetosheath. These observations are consistent with recent high-resolution and low-noise kinetic simulations of asymmetric reconnection. Patchy energy conversion is observed also in an EDR at the magnetotail, where the inter-spacecraft separation was ∼ 1 d<sub>e</sub>. Electric field measurements are different among the spacecraft suggesting inhomogeneities at the electron scale. However, in this case the current density appear homogeneous in the EDR suggesting that the structuring may be sourced from a different kind of electron dynamics in the magnetotail.</p&gt

Fire Hose Instability in the Multiple Magnetic Reconnection

International audienceWe present observations of multiple reconnection in the Earth's magnetotail. In particular, we observe an ion temperature anisotropy characterized by large temperature along the magnetic field, between the two active X-lines. The anisotropy is associated with right-hand polarized waves at frequencies lower than the ion cyclotron frequency and propagating obliquely to the background magnetic field. We show that the observed anisotropy and the wave properties are consistent with linear kinetic theory of fire hose instability. The observations are in agreement with the particle-in-cell simulations of multiple reconnection. The results suggest that the fire hose instability can develop during multiple reconnection as a consequence of the ion parallel anisotropy that is produced by counter-streaming ions trapped between the X-lines