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1.
Nature ; 569(7757): E9, 2019 May.
Artículo en Inglés | MEDLINE | ID: mdl-31073227

RESUMEN

Change history: In this Letter, the y-axis values in Fig. 3f should go from 4 to -8 (rather than from 4 to -4), the y-axis values in Fig. 3h should appear next to the major tick marks (rather than the minor ticks), and in Fig. 1b, the arrows at the top and bottom of the electron-scale current sheet were going in the wrong direction; these errors have been corrected online.

2.
Nature ; 557(7704): 202-206, 2018 05.
Artículo en Inglés | MEDLINE | ID: mdl-29743689

RESUMEN

Magnetic reconnection in current sheets is a magnetic-to-particle energy conversion process that is fundamental to many space and laboratory plasma systems. In the standard model of reconnection, this process occurs in a minuscule electron-scale diffusion region1,2. On larger scales, ions couple to the newly reconnected magnetic-field lines and are ejected away from the diffusion region in the form of bi-directional ion jets at the ion Alfvén speed3-5. Much of the energy conversion occurs in spatially extended ion exhausts downstream of the diffusion region 6 . In turbulent plasmas, which contain a large number of small-scale current sheets, reconnection has long been suggested to have a major role in the dissipation of turbulent energy at kinetic scales7-11. However, evidence for reconnection plasma jetting in small-scale turbulent plasmas has so far been lacking. Here we report observations made in Earth's turbulent magnetosheath region (downstream of the bow shock) of an electron-scale current sheet in which diverging bi-directional super-ion-Alfvénic electron jets, parallel electric fields and enhanced magnetic-to-particle energy conversion were detected. Contrary to the standard model of reconnection, the thin reconnecting current sheet was not embedded in a wider ion-scale current layer and no ion jets were detected. Observations of this and other similar, but unidirectional, electron jet events without signatures of ion reconnection reveal a form of reconnection that can drive turbulent energy transfer and dissipation in electron-scale current sheets without ion coupling.

3.
Ultrasound Obstet Gynecol ; 58(3): 457-468, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-33314410

RESUMEN

OBJECTIVE: To evaluate the ability of demographic and sonographic variables and the Proactive Molecular Risk Classifier for Endometrial cancer (ProMisE) classification to predict preoperatively tumor recurrence or progression in women with endometrial cancer. METHODS: The study included 339 women with histologically confirmed endometrial cancer who underwent expert transvaginal ultrasound in a single center before surgery as part of the prospective International Endometrial Tumor Analysis 4 study or who were evaluated using the same protocol. The tumors were classified according to histotype, FIGO (International Federation of Gynecology and Obstetrics) grade and FIGO stage. In addition, molecular analysis was performed for classification into the four ProMisE subtypes: polymerase-ϵ exonuclease domain mutations (POLE EDM), mismatch repair proteins deficiency (MMR-D), protein 53 wild type (p53 wt) and protein 53 abnormal (p53 abn). Demographic and preoperative sonographic characteristics, tumor recurrence or progression and survival were compared between the ProMisE subgroups. Cox regression analysis was used to identify prognostic factors associated with recurrence or progression, using univariable models to study crude associations and multivariable models to study adjusted associations. Logistic regression and receiver-operating-characteristics (ROC)-curve analysis were used to assess the predictive ability of the preoperative prognostic factors regarding recurrence or progression of cancer within 3 years after surgery, and to compare their predictive ability to that of the European Society for Medical Oncology (ESMO) preoperative (based on depth of myometrial invasion, histotype and grade) and postoperative (based on histotype, grade, surgical stage and lymphovascular space invasion) risk classifications. In a separate subanalysis, cases were stratified according to ProMisE p53 abn status (present vs absent) and sonographic tumor size (anteroposterior (AP) diameter < 2 cm vs ≥ 2 cm). RESULTS: Median follow-up time from surgery was 58 months (interquartile range, 48-71 months; range, 0-102 months). Recurrence or progression of cancer occurred in 51/339 (15%) women, comprising 14% of those with MMR-D, 8% of those with POLE EDM, 9% of those with p53 wt and 45% of those with p53 abn ProMisE subtype. On multivariable analysis, age, waist circumference, ProMisE subtype and tumor extension and AP diameter on ultrasound were associated with tumor recurrence or progression. A multivariable model comprising ProMisE subtype, age, waist circumference and sonographic tumor extension and size (area under the ROC curve (AUC), 0.89 (95% CI, 0.85-0.93)) had comparable ability to predict tumor recurrence/progression to that of a multivariable model comprising histotype, grade, age, waist circumference and sonographic tumor extension and size (AUC, 0.88 (95% CI, 0.83-0.92)), and better predictive ability than both the preoperative (AUC, 0.74 (95% CI, 0.67-0.82); P < 0.01) and postoperative (AUC, 0.79 (95% CI, 0.72-0.86); P < 0.01) ESMO risk classifications. Women with a combination of non-p53 abn subtype and tumor size < 2 cm (164/339 (48%)) had a very low risk (1.8%) of tumor recurrence or progression. CONCLUSIONS: The combination of demographic characteristics, sonographic findings and ProMisE subtype had better preoperative predictive ability for tumor recurrence or progression than did the ESMO classification, supporting their use in the preoperative risk stratification of women with endometrial cancer. The combination of p53 status with ultrasound tumor size has the potential to identify preoperatively a large group of women with a very low risk of recurrence or progression. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology. - Legal Statement: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.


Asunto(s)
Neoplasias Endometriales/clasificación , Neoplasias Endometriales/genética , Tipificación Molecular/estadística & datos numéricos , Recurrencia Local de Neoplasia/genética , Ultrasonografía/estadística & datos numéricos , Anciano , Progresión de la Enfermedad , Neoplasias Endometriales/cirugía , Femenino , Humanos , Modelos Logísticos , Persona de Mediana Edad , Tipificación Molecular/métodos , Valor Predictivo de las Pruebas , Periodo Preoperatorio , Estudios Prospectivos , Curva ROC , Medición de Riesgo , Vagina/diagnóstico por imagen
4.
Phys Rev Lett ; 124(6): 065101, 2020 Feb 14.
Artículo en Inglés | MEDLINE | ID: mdl-32109113

RESUMEN

The first-order Fermi acceleration of electrons requires an injection of electrons into a mildly relativistic energy range. However, the mechanism of injection has remained a puzzle both in theory and observation. We present direct evidence for a novel stochastic shock drift acceleration theory for the injection obtained with Magnetospheric Multiscale observations at the Earth's bow shock. The theoretical model can explain electron acceleration to mildly relativistic energies at high-speed astrophysical shocks, which may provide a solution to the long-standing issue of electron injection.

5.
Phys Rev Lett ; 125(26): 265102, 2020 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-33449730

RESUMEN

Magnetic reconnection is of fundamental importance to plasmas because of its role in releasing and repartitioning stored magnetic energy. Previous results suggest that this energy is predominantly released as ion enthalpy flux along the reconnection outflow. Using Magnetospheric Multiscale data we find the existence of very significant electron energy flux densities in the vicinity of the magnetopause electron dissipation region, orthogonal to the ion energy outflow. These may significantly impact models of electron transport, wave generation, and particle acceleration.

6.
Phys Rev Lett ; 125(2): 025103, 2020 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-32701350

RESUMEN

We report measurements of lower-hybrid drift waves driving electron heating and vortical flows in an electron-scale reconnection layer under a guide field. Electrons accelerated by the electrostatic potential of the waves exhibit perpendicular and nongyrotropic heating. The vortical flows generate magnetic field perturbations comparable to the guide field magnitude. The measurements reveal a new regime of electron-wave interaction and how this interaction modifies the electron dynamics in the reconnection layer.

7.
Ultrasound Obstet Gynecol ; 55(1): 115-124, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31225683

RESUMEN

OBJECTIVES: To compare the performance of ultrasound measurements and subjective ultrasound assessment (SA) in detecting deep myometrial invasion (MI) and cervical stromal invasion (CSI) in women with endometrial cancer, overall and according to whether they had low- or high-grade disease separately, and to validate published measurement cut-offs and prediction models to identify MI, CSI and high-risk disease (Grade-3 endometrioid or non-endometrioid cancer and/or deep MI and/or CSI). METHODS: The study comprised 1538 patients with endometrial cancer from the International Endometrial Tumor Analysis (IETA)-4 prospective multicenter study, who underwent standardized expert transvaginal ultrasound examination. SA and ultrasound measurements were used to predict deep MI and CSI. We assessed the diagnostic accuracy of the tumor/uterine anteroposterior (AP) diameter ratio for detecting deep MI and that of the distance from the lower margin of the tumor to the outer cervical os (Dist-OCO) for detecting CSI. We also validated two two-step strategies for the prediction of high-risk cancer; in the first step, biopsy-confirmed Grade-3 endometrioid or mucinous or non-endometrioid cancers were classified as high-risk cancer, while the second step encompassed the application of a mathematical model to classify the remaining tumors. The 'subjective prediction model' included biopsy grade (Grade 1 vs Grade 2) and subjective assessment of deep MI or CSI (presence or absence) as variables, while the 'objective prediction model' included biopsy grade (Grade 1 vs Grade 2) and minimal tumor-free margin. The predictive performance of the two two-step strategies was compared with that of simply classifying patients as high risk if either deep MI or CSI was suspected based on SA or if biopsy showed Grade-3 endometrioid or mucinous or non-endometrioid histotype (i.e. combining SA with biopsy grade). Histological assessment from hysterectomy was considered the reference standard. RESULTS: In 1275 patients with measurable lesions, the sensitivity and specificity of SA for detecting deep MI was 70% and 80%, respectively, in patients with a Grade-1 or -2 endometrioid or mucinous tumor vs 76% and 64% in patients with a Grade-3 endometrioid or mucinous or a non-endometrioid tumor. The corresponding values for the detection of CSI were 51% and 94% vs 50% and 91%. Tumor AP diameter and tumor/uterine AP diameter ratio showed the best performance for predicting deep MI (area under the receiver-operating characteristics curve (AUC) of 0.76 and 0.77, respectively), and Dist-OCO had the best performance for predicting CSI (AUC, 0.72). The proportion of patients classified correctly as having high-risk cancer was 80% when simply combining SA with biopsy grade vs 80% and 74% when using the subjective and objective two-step strategies, respectively. The subjective and objective models had an AUC of 0.76 and 0.75, respectively, when applied to Grade-1 and -2 endometrioid tumors. CONCLUSIONS: In the hands of experienced ultrasound examiners, SA was superior to ultrasound measurements for the prediction of deep MI and CSI of endometrial cancer, especially in patients with a Grade-1 or -2 tumor. The mathematical models for the prediction of high-risk cancer performed as expected. The best strategies for predicting high-risk endometrial cancer were combining SA with biopsy grade and the subjective two-step strategy, both having an accuracy of 80%. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.


Asunto(s)
Neoplasias Endometriales/diagnóstico por imagen , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias Endometriales/patología , Europa (Continente) , Femenino , Humanos , Persona de Mediana Edad , Invasividad Neoplásica , Estadificación de Neoplasias , Estudios Prospectivos , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Ultrasonografía
8.
Ultrasound Obstet Gynecol ; 56(3): 443-452, 2020 09.
Artículo en Inglés | MEDLINE | ID: mdl-31840873

RESUMEN

OBJECTIVE: To develop a preoperative risk model, using endometrial biopsy results and clinical and ultrasound variables, to predict the individual risk of lymph-node metastases in women with endometrial cancer. METHODS: A mixed-effects logistic regression model for prediction of lymph-node metastases was developed in 1501 prospectively included women with endometrial cancer undergoing transvaginal ultrasound examination before surgery, from 16 European centers. Missing data, including missing lymph-node status, were imputed. Discrimination, calibration and clinical utility of the model were evaluated using leave-center-out cross validation. The predictive performance of the model was compared with that of risk classification from endometrial biopsy alone (high-risk defined as endometrioid cancer Grade 3/non-endometrioid cancer) or combined endometrial biopsy and ultrasound (high-risk defined as endometrioid cancer Grade 3/non-endometrioid cancer/deep myometrial invasion/cervical stromal invasion/extrauterine spread). RESULTS: Lymphadenectomy was performed in 691 women, of whom 127 had lymph-node metastases. The model for prediction of lymph-node metastases included the predictors age, duration of abnormal bleeding, endometrial biopsy result, tumor extension and tumor size according to ultrasound and undefined tumor with an unmeasurable endometrium. The model's area under the curve was 0.73 (95% CI, 0.68-0.78), the calibration slope was 1.06 (95% CI, 0.79-1.34) and the calibration intercept was 0.06 (95% CI, -0.15 to 0.27). Using a risk threshold for lymph-node metastases of 5% compared with 20%, the model had, respectively, a sensitivity of 98% vs 48% and specificity of 11% vs 80%. The model had higher sensitivity and specificity than did classification as high-risk, according to endometrial biopsy alone (50% vs 35% and 80% vs 77%, respectively) or combined endometrial biopsy and ultrasound (80% vs 75% and 53% vs 52%, respectively). The model's clinical utility was higher than that of endometrial biopsy alone or combined endometrial biopsy and ultrasound at any given risk threshold. CONCLUSIONS: Based on endometrial biopsy results and clinical and ultrasound characteristics, the individual risk of lymph-node metastases in women with endometrial cancer can be estimated reliably before surgery. The model is superior to risk classification by endometrial biopsy alone or in combination with ultrasound. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.


Asunto(s)
Carcinoma Endometrioide/diagnóstico por imagen , Neoplasias Endometriales/diagnóstico por imagen , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma Endometrioide/secundario , Estudios de Cohortes , Neoplasias Endometriales/patología , Femenino , Humanos , Modelos Lineales , Ganglios Linfáticos , Metástasis Linfática , Persona de Mediana Edad , Estadificación de Neoplasias , Estudios Prospectivos , Factores de Riesgo , Sensibilidad y Especificidad , Ultrasonografía
9.
BJOG ; 126(13): 1577-1586, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31483935

RESUMEN

OBJECTIVE: To estimate incidence, trends over time, and risk factors for massive blood transfusions in obstetric patients. A secondary aim was to evaluate transfusion ratios in relation to massive transfusion. DESIGN: Population-based cohort. SETTING: Five hospitals, in the Stockholm County, Sweden, from 1990 to 2011. POPULATION: All women that gave birth in Stockholm county, Sweden, and who received blood transfusions postpartum between 1990 and 2011. METHODS: Data on pregnancies and deliveries from the Swedish National Medical Birth Registry was cross-linked to the Stockholm transfusion database. Massive blood transfusion was defined as the transfusion of ≥10 units of red blood cells from partus through the next day. MAIN OUTCOME MEASURES: Main primary outcome was massive blood transfusion postpartum. RESULTS: Our cohort comprised 517 874 deliveries. Massive blood transfusion occurred in 277 women, for an incidence of 5.3 per 10 000 deliveries, and increased by 30% (P < 0.001) between the first and the second half of the study period. Major risk factors apparent before delivery were abnormal placentation (odds ratio [OR] 41; 95% CI 29.3-58.1), pre-eclampsia/placental abruption (OR 4; 95% CI 2.8-5.6), and previous caesarean delivery (OR 4; 95% CI 3.1-6.0). Risk factors at time of delivery were uterine rupture, atonic uterus, and caesarean delivery (OR 38, 17, and 3, respectively). CONCLUSION: We found an increasing trend in the postpartum rate of massive transfusion. Women with abnormal placentation were found to have the highest increased risk. Improved antenatal awareness of these women at risk might improve management and reduce the rate of massive transfusion. TWEETABLE ABSTRACT: Risk of massive blood transfusion in obstetric patients increases with placental complications and prior caesarean section.


Asunto(s)
Transfusión Sanguínea , Cesárea/estadística & datos numéricos , Parto Obstétrico/estadística & datos numéricos , Hemorragia Posparto/epidemiología , Desprendimiento Prematuro de la Placenta/epidemiología , Adulto , Transfusión Sanguínea/estadística & datos numéricos , Cesárea/efectos adversos , Parto Obstétrico/efectos adversos , Femenino , Encuestas Epidemiológicas , Humanos , Histerectomía/estadística & datos numéricos , Incidencia , Placenta Accreta/epidemiología , Hemorragia Posparto/etiología , Hemorragia Posparto/terapia , Embarazo , Factores de Riesgo , Suecia/epidemiología , Inercia Uterina/epidemiología , Inercia Uterina/terapia
10.
BJOG ; 126(3): 370-381, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-29727918

RESUMEN

OBJECTIVE: International comparison of complete uterine rupture. DESIGN: Descriptive multi-country population-based study. SETTING: International. POPULATION: International Network of Obstetric Survey Systems (INOSS). METHODS: We merged individual data, collected prospectively in nine population-based studies, of women with complete uterine rupture, defined as complete disruption of the uterine muscle and the uterine serosa, regardless of symptoms and rupture of fetal membranes. MAIN OUTCOME MEASURES: Prevalence of complete uterine rupture, regional variation and correlation with rates of caesarean section (CS) and trial of labour after CS (TOLAC). Severe maternal and perinatal morbidity and mortality. RESULTS: We identified 864 complete uterine ruptures in 2 625 017 deliveries. Overall prevalence was 3.3 (95% CI 3.1-3.5) per 10 000 deliveries, 22 (95% CI 21-24) in women with and 0.6 (95% CI 0.5-0.7) in women without previous CS. Prevalence in women with previous CS was negatively correlated with previous CS rate (ρ = -0.917) and positively correlated with TOLAC rate of the background population (ρ = 0.600). Uterine rupture resulted in peripartum hysterectomy in 87 of 864 women (10%, 95% CI 8-12%) and in a perinatal death in 116 of 874 infants (13.3%, 95% CI 11.2-15.7) whose mother had uterine rupture. Overall rate of neonatal asphyxia was 28% in neonates who survived. CONCLUSIONS: Higher prevalence of complete uterine ruptures per TOLAC was observed in countries with low previous CS and high TOLAC rates. Rates of hysterectomy and perinatal death are about 10% following complete uterine rupture, but in women undergoing TOLAC the rates are extremely low (only 2.2 and 3.2 per 10 000 TOLACs, respectively.) TWEETABLE ABSTRACT: Prevalence of complete uterine rupture is higher in countries with low previous CS and high TOLAC rates.


Asunto(s)
Asfixia Neonatal/epidemiología , Cesárea Repetida/estadística & datos numéricos , Histerectomía/estadística & datos numéricos , Muerte Materna , Muerte Perinatal , Esfuerzo de Parto , Rotura Uterina/epidemiología , Cesárea/estadística & datos numéricos , Femenino , Humanos , Recién Nacido , Embarazo , Prevalencia , Encuestas y Cuestionarios , Parto Vaginal Después de Cesárea
11.
Geophys Res Lett ; 46(11): 5707-5716, 2019 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-31423036

RESUMEN

Electromagnetic ion cyclotron (EMIC) waves at large L shells were observed away from the magnetic equator by the Magnetospheric MultiScale (MMS) mission nearly continuously for over four hours on 28 October 2015. During this event, the wave Poynting vector direction systematically changed from parallel to the magnetic field (toward the equator), to bidirectional, to antiparallel (away from the equator). These changes coincide with the shift in the location of the minimum in the magnetic field in the southern hemisphere from poleward to equatorward of MMS. The local plasma conditions measured with the EMIC waves also suggest that the outer magnetospheric region sampled during this event was generally unstable to EMIC wave growth. Together, these observations indicate that the bidirectionally propagating wave packets were not a result of reflection at high latitudes but that MMS passed through an off-equator EMIC wave source region associated with the local minimum in the magnetic field.

12.
Phys Rev Lett ; 120(22): 225101, 2018 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-29906189

RESUMEN

Electron heating at Earth's quasiperpendicular bow shock has been surmised to be due to the combined effects of a quasistatic electric potential and scattering through wave-particle interaction. Here we report the observation of electron distribution functions indicating a new electron heating process occurring at the leading edge of the shock front. Incident solar wind electrons are accelerated parallel to the magnetic field toward downstream, reaching an electron-ion relative drift speed exceeding the electron thermal speed. The bulk acceleration is associated with an electric field pulse embedded in a whistler-mode wave. The high electron-ion relative drift is relaxed primarily through a nonlinear current-driven instability. The relaxed distributions contain a beam traveling toward the shock as a remnant of the accelerated electrons. Similar distribution functions prevail throughout the shock transition layer, suggesting that the observed acceleration and thermalization is essential to the cross-shock electron heating.

13.
Geophys Res Lett ; 45(10): 4569-4577, 2018 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-31031447

RESUMEN

Magnetospheric Multiscale observations are used to probe the structure and temperature profile of a guide field reconnection exhaust ~100 ion inertial lengths downstream from the X-line in the Earth's magnetosheath. Asymmetric Hall electric and magnetic field signatures were detected, together with a density cavity confined near 1 edge of the exhaust and containing electron flow toward the X-line. Electron holes were also detected both on the cavity edge and at the Hall magnetic field reversal. Predominantly parallel ion and electron heating was observed in the main exhaust, but within the cavity, electron cooling and enhanced parallel ion heating were found. This is explained in terms of the parallel electric field, which inhibits electron mixing within the cavity on newly reconnected field lines but accelerates ions. Consequently, guide field reconnection causes inhomogeneous changes in ion and electron temperature across the exhaust.

14.
Ultrasound Obstet Gynecol ; 51(6): 818-828, 2018 06.
Artículo en Inglés | MEDLINE | ID: mdl-28944985

RESUMEN

OBJECTIVE: To describe the sonographic features of endometrial cancer in relation to tumor stage, grade and histological type, using the International Endometrial Tumor Analysis (IETA) terminology. METHODS: This was a prospective multicenter study of 1714 women with biopsy-confirmed endometrial cancer undergoing standardized transvaginal grayscale and Doppler ultrasound examination according to the IETA study protocol, by experienced ultrasound examiners using high-end ultrasound equipment. Clinical and sonographic data were entered into a web-based database. We assessed how strongly sonographic characteristics, according to IETA, were associated with outcome at hysterectomy, i.e. tumor stage, grade and histological type, using univariable logistic regression and the c-statistic. RESULTS: In total, 1538 women were included in the final analysis. Median age was 65 (range, 27-98) years, median body mass index was 28.4 (range 16-67) kg/m2 , 1377 (89.5%) women were postmenopausal and 1296 (84.3%) reported abnormal vaginal bleeding. Grayscale and color Doppler features varied according to grade and stage of tumor. High-risk tumors, compared with low-risk tumors, were less likely to have regular endometrial-myometrial junction (difference of -23%; 95% CI, -27 to -18%), were larger (mean endometrial thickness; difference of +9%; 95% CI, +8 to +11%), and were more likely to have non-uniform echogenicity (difference of +7%; 95% CI, +1 to +13%), a multiple, multifocal vessel pattern (difference of +21%; 95% CI, +16 to +26%) and a moderate or high color score (difference of +22%; 95% CI, +18 to +27%). CONCLUSION: Grayscale and color Doppler sonographic features are associated with grade and stage of tumor, and differ between high- and low-risk endometrial cancer. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.


Asunto(s)
Neoplasias Endometriales/diagnóstico por imagen , Clasificación del Tumor , Ultrasonografía Doppler en Color/normas , Adulto , Anciano , Anciano de 80 o más Años , Conferencias de Consenso como Asunto , Estudios Transversales , Neoplasias Endometriales/clasificación , Neoplasias Endometriales/patología , Femenino , Humanos , Persona de Mediana Edad , Estudios Prospectivos , Reproducibilidad de los Resultados , Terminología como Asunto
15.
Phys Rev Lett ; 118(26): 265101, 2017 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-28707935

RESUMEN

We report observations from the Magnetospheric Multiscale (MMS) satellites of the electron jet in a symmetric magnetic reconnection event with moderate guide field. All four spacecraft sampled the ion diffusion region and observed the electron exhaust. The observations suggest that the presence of the guide field leads to an asymmetric Hall field, which results in an electron jet skewed towards the separatrix with a nonzero component along the magnetic field. The jet appears in conjunction with a spatially and temporally persistent parallel electric field ranging from -3 to -5 mV/m, which led to dissipation on the order of 8 nW/m^{3}. The parallel electric field heats electrons that drift through it, and is associated with a streaming instability and electron phase space holes.

16.
Phys Rev Lett ; 119(2): 025101, 2017 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-28753352

RESUMEN

During a magnetopause crossing the Magnetospheric Multiscale spacecraft encountered an electron diffusion region (EDR) of asymmetric reconnection. The EDR is characterized by agyrotropic beam and crescent electron distributions perpendicular to the magnetic field. Intense upper-hybrid (UH) waves are found at the boundary between the EDR and magnetosheath inflow region. The UH waves are generated by the agyrotropic electron beams. The UH waves are sufficiently large to contribute to electron diffusion and scattering, and are a potential source of radio emission near the EDR. These results provide observational evidence of wave-particle interactions at an EDR, and suggest that waves play an important role in determining the electron dynamics.

17.
Phys Rev Lett ; 119(5): 055101, 2017 Aug 04.
Artículo en Inglés | MEDLINE | ID: mdl-28949734

RESUMEN

We report unambiguous in situ observation of the coalescence of macroscopic flux ropes by the magnetospheric multiscale (MMS) mission. Two coalescing flux ropes with sizes of ∼1 R_{E} were identified at the subsolar magnetopause by the occurrence of an asymmetric quadrupolar signature in the normal component of the magnetic field measured by the MMS spacecraft. An electron diffusion region (EDR) with a width of four local electron inertial lengths was embedded within the merging current sheet. The EDR was characterized by an intense parallel electric field, significant energy dissipation, and suprathermal electrons. Although the electrons were organized by a large guide field, the small observed electron pressure nongyrotropy may be sufficient to support a significant fraction of the parallel electric field within the EDR. Since the flux ropes are observed in the exhaust region, we suggest that secondary EDRs are formed further downstream of the primary reconnection line between the magnetosheath and magnetospheric fields.

18.
J Endocrinol Invest ; 40(10): 1049-1059, 2017 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-28555324

RESUMEN

Gestational diabetes mellitus (GDM), defined as any glucose intolerance with the onset or first recognition during pregnancy, is characterized by rising incidence, fostered by the worldwide increase of pathological nutritional status from young age. Clinical research has intended to identify potential risk factors, suggested improvements in screening strategies, and recommended the combination between promotion of an appropriate lifestyle before and during pregnancy and selected therapeutic approaches. Preventing pathological hyperglycemia could have several benefits, ranging from clinical side (reduction in the risk of adverse perinatal and long-term sequelae) to financial side (cost reduction to healthcare systems). Among risk factors recognized, deficiency in 25-hydroxyvitamin D [25(OH)D], already acknowledged as involved in calcium homeostasis, pathogenesis of cardiovascular, oncological, infective and immunity diseases, could predispose to the development of both type 1 and 2 diabetes, modifying the activity of pancreatic ß-cells vitamin D (VD) receptor. In pregnant women, lower 25(OH)D concentrations have been suggested to present an inverse association with maternal glycaemia, insulin resistance, and increased risk of GDM. In spite of growing body of evidence, there is not full agreement on the therapeutic association between GDM based on VD deficiency and 25(OH)D supplementation. In the attempt to bring up-to-date the role of low VD levels on subsequent development of GDM, this narrative review, based on medium-high-quality randomized clinical trials, systematic reviews, and meta-analysis published in last decade, has a twofold purpose: firstly, to elucidate the relationship between maternal VD status and GDM; and secondly, to illuminate the impact of VD supplementation on GDM onset.


Asunto(s)
Biomarcadores/sangre , Diabetes Gestacional/diagnóstico , Diabetes Gestacional/etiología , Deficiencia de Vitamina D/complicaciones , Vitamina D/sangre , Vitaminas/sangre , Diabetes Gestacional/sangre , Femenino , Humanos , Embarazo , Factores de Riesgo
19.
J Intern Med ; 280(4): 375-87, 2016 10.
Artículo en Inglés | MEDLINE | ID: mdl-26992108

RESUMEN

OBJECTIVE: Women with active sunlight exposure habits experience a lower mortality rate than women who avoid sun exposure; however, they are at an increased risk of skin cancer. We aimed to explore the differences in main causes of death according to sun exposure. METHODS: We assessed the differences in sun exposure as a risk factor for all-cause mortality in a competing risk scenario for 29 518 Swedish women in a prospective 20-year follow-up of the Melanoma in Southern Sweden (MISS) cohort. Women were recruited from 1990 to 1992 (aged 25-64 years at the start of the study). We obtained detailed information at baseline on sun exposure habits and potential confounders. The data were analysed using modern survival statistics. RESULTS: Women with active sun exposure habits were mainly at a lower risk of cardiovascular disease (CVD) and noncancer/non-CVD death as compared to those who avoided sun exposure. As a result of their increased survival, the relative contribution of cancer death increased in these women. Nonsmokers who avoided sun exposure had a life expectancy similar to smokers in the highest sun exposure group, indicating that avoidance of sun exposure is a risk factor for death of a similar magnitude as smoking. Compared to the highest sun exposure group, life expectancy of avoiders of sun exposure was reduced by 0.6-2.1 years. CONCLUSION: The longer life expectancy amongst women with active sun exposure habits was related to a decrease in CVD and noncancer/non-CVD mortality, causing the relative contribution of death due to cancer to increase.


Asunto(s)
Causas de Muerte , Luz Solar , Adulto , Enfermedades Cardiovasculares/mortalidad , Exposición a Riesgos Ambientales/efectos adversos , Femenino , Estudios de Seguimiento , Humanos , Esperanza de Vida , Melanoma/prevención & control , Persona de Mediana Edad , Neoplasias/mortalidad , Factores de Riesgo , Neoplasias Cutáneas/prevención & control , Luz Solar/efectos adversos , Suecia
20.
Phys Rev Lett ; 117(16): 165101, 2016 Oct 14.
Artículo en Inglés | MEDLINE | ID: mdl-27792387

RESUMEN

Collisionless shock nonstationarity arising from microscale physics influences shock structure and particle acceleration mechanisms. Nonstationarity has been difficult to quantify due to the small spatial and temporal scales. We use the closely spaced (subgyroscale), high-time-resolution measurements from one rapid crossing of Earth's quasiperpendicular bow shock by the Magnetospheric Multiscale (MMS) spacecraft to compare competing nonstationarity processes. Using MMS's high-cadence kinetic plasma measurements, we show that the shock exhibits nonstationarity in the form of ripples.

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