717 research outputs found

    Solar Stereoscopy with STEREO/EUVI A and B spacecraft from small (6 deg) to large (170 deg) spacecraft separation angles

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    We performed for the first time stereoscopic triangulation of coronal loops in active regions over the entire range of spacecraft separation angles (αsep≈6∘,43∘,89∘,127∘\alpha_{sep}\approx 6^\circ, 43^\circ, 89^\circ, 127^\circ, and 170∘170^\circ). The accuracy of stereoscopic correlation depends mostly on the viewing angle with respect to the solar surface for each spacecraft, which affects the stereoscopic correspondence identification of loops in image pairs. From a simple theoretical model we predict an optimum range of αsep≈22∘−125∘\alpha_{sep} \approx 22^\circ-125^\circ, which is also experimentally confirmed. The best accuracy is generally obtained when an active region passes the central meridian (viewed from Earth), which yields a symmetric view for both STEREO spacecraft and causes minimum horizontal foreshortening. For the extended angular range of αsep≈6∘−127∘\alpha_{sep}\approx 6^\circ-127^{\circ} we find a mean 3D misalignment angle of μPF≈21∘−39∘\mu_{PF} \approx 21^\circ-39^\circ of stereoscopically triangulated loops with magnetic potential field models, and μFFF≈15∘−21∘\mu_{FFF} \approx 15^\circ-21^\circ for a force-free field model, which is partly caused by stereoscopic uncertainties μSE≈9∘\mu_{SE} \approx 9^\circ. We predict optimum conditions for solar stereoscopy during the time intervals of 2012--2014, 2016--2017, and 2021--2023.Comment: Solar Physics, (in press), 22 pages, 9 figure

    A Nonlinear Force-Free Magnetic Field Approximation Suitable for Fast Forward-Fitting to Coronal Loops. II. Numeric Code and Tests

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    Based on a second-order approximation of nonlinear force-free magnetic field solutions in terms of uniformly twisted field lines derived in Paper I, we develop here a numeric code that is capable to forward-fit such analytical solutions to arbitrary magnetogram (or vector magnetograph) data combined with (stereoscopically triangulated) coronal loop 3D coordinates. We test the code here by forward-fitting to six potential field and six nonpotential field cases simulated with our analytical model, as well as by forward-fitting to an exactly force-free solution of the Low and Lou (1990) model. The forward-fitting tests demonstrate: (i) a satisfactory convergence behavior (with typical misalignment angles of μ≈1∘−10∘\mu \approx 1^\circ-10^\circ), (ii) relatively fast computation times (from seconds to a few minutes), and (iii) the high fidelity of retrieved force-free α\alpha-parameters (αfit/αmodel≈0.9−1.0\alpha_{\rm fit}/\alpha_{\rm model} \approx 0.9-1.0 for simulations and αfit/αmodel≈0.7±0.3\alpha_{\rm fit}/\alpha_{\rm model} \approx 0.7\pm0.3 for the Low and Lou model). The salient feature of this numeric code is the relatively fast computation of a quasi-forcefree magnetic field, which closely matches the geometry of coronal loops in active regions, and complements the existing {\sl nonlinear force-free field (NLFFF)} codes based on photospheric magnetograms without coronal constraints.Comment: Solar PHysics, (in press), 25 pages, 11 figure

    A Nonlinear Force-Free Magnetic Field Approximation Suitable for Fast Forward-Fitting to Coronal Loops. I. Theory

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    We derive an analytical approximation of nonlinear force-free magnetic field solutions (NLFFF) that can efficiently be used for fast forward-fitting to solar magnetic data, constrained either by observed line-of-sight magnetograms and stereoscopically triangulated coronal loops, or by 3D vector-magnetograph data. The derived NLFFF solutions provide the magnetic field components Bx(x)B_x({\bf x}), By(x)B_y({\bf x}), Bz(x)B_z({\bf x}), the force-free parameter α(x)\alpha({\bf x}), the electric current density j(x){\bf j}({\bf x}), and are accurate to second-order (of the nonlinear force-free α\alpha-parameter). The explicit expressions of a force-free field can easily be applied to modeling or forward-fitting of many coronal phenomena.Comment: Solar Physics (in press), 26 pages, 11 figure

    Patterns of Maternal Distress from Pregnancy Through Childhood Predict Psychopathology During Early Adolescence

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    Capitalizing on a longitudinal cohort followed from gestation through adolescence (201 mother–child dyads), we investigate the contributions of severity and stability of both maternal depressive and perceived stress symptoms to adolescent psychopathology. Maternal depressive and perceived stress trajectories from pregnancy through adolescence were identified with latent class growth analyses, and associations with adolescent internalizing and externalizing symptoms were examined. For both depression and stress, the most common trajectory group comprised mothers displaying stable and low symptom levels over time, and adolescents of these mothers had the fewest internalizing and externalizing symptoms. Maternal membership to one or more aberrant trajectory groups predicted higher levels of internalizing and externalizing symptoms, determined by both maternal and adolescent self-report. This study indicates that profiles of multiple indicators of maternal psychopathology assessed across childhood, beginning prenatally, can provide critical additional insight into child psychopathology risk

    Maternal Prenatal Cortisol Programs the Infant Hypothalamic–Pituitary–Adrenal Axis

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    One of the key proposed agents of fetal programming is exposure to maternal glucocorticoids. Experimental animal studies provide evidence that prenatal exposure to elevated maternal glucocorticoids has consequences for hypothalamic–pituitary–adrenal (HPA) axis functioning in the offspring. There are very few direct tests of maternal glucocorticoids, such as cortisol, during human pregnancy and associations with infant cortisol reactivity. The current study examined the link between maternal prenatal cortisol trajectories and infant cortisol reactivity to the pain of inoculation in a sample of 152 mother-infant (47.4% girls) pairs. The results from the current study provide insight into fetal programming of the infant HPA axis, demonstrating that elevated prenatal maternal cortisol is associated with a larger infant cortisol response to challenge at both 6 and 12 months of age

    Development of Fetal Movement Between 26 and 36 Weeks’ Gestation in Response to Vibroacoustic Stimulation

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    BACKGROUND: Ultrasound observation of fetal movement has documented general trends in motor development and fetal age when motor response to stimulation is observed. Evaluation of fetal movement quality, in addition to specific motor activity, may improve documentation of motor development and highlight specific motor responses to stimulation. AIM: The aim of this investigation was to assess fetal movement at 26 and 36-weeks gestation during three conditions (baseline, immediate response to vibro-acoustic stimulation (VAS), and post-response). DESIGN: A prospective, longitudinal design was utilized. SUBJECTS: Twelve normally developing fetuses, eight females and four males, were examined with continuous ultrasound imaging. OUTCOME MEASURES: The fetal neurobehavioral coding system (FENS) was used to evaluate the quality of motor activity during 10-s epochs over the three conditions. RESULTS: Seventy-five percent of the fetuses at the 26-week assessment and 100% of the fetuses at the 36-week assessment responded with movement immediately following stimulation. Significant differences in head, fetal breathing, general, limb, and mouthing movements were detected between the 26 and 36-week assessments. Movement differences between conditions were detected in head, fetal breathing, limb, and mouthing movements. CONCLUSION: Smoother and more complex movement was observed with fetal maturation. Following VAS stimulation, an immediate increase of large, jerky movements suggests instability in fetal capabilities. Fetal movement quality changes over gestation may reflect sensorimotor synaptogenesis in the central nervous system, while observation of immature movement patterns following VAS stimulation may reflect movement pattern instability

    Temperament Factors and Dimensional, Latent Bifactor Models of child psychopathology: Transdiagnostic and Specific Associations in Two Youth Samples

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    Common emotional and behavioral symptoms co-occur and are associated with core temperament factors. This study investigated links between temperament and dimensional, latent psychopathology factors, including a general common psychopathology factor (p factor) and specific latent internalizing and externalizing liabilities, as captured by a bifactor model, in two independent samples of youth. Specifically, we tested the hypothesis that temperament factors of negative affectivity (NA), positive affectivity (PA), and effortful control (EC) could serve as both transdiagnostic and specific risks in relation to recent bifactor models of child psychopathology. Sample 1 included 571 youth (average age 13.6, SD = 2.37, range 9.3–17.5) with both youth and parent report. Sample 2 included 554 preadolescent children (average age 7.7, SD = 1.35, range = 5–11 years) with parent report. Structural equation modeling showed that the latent bifactor models fit in both samples. Replicated in both samples, the p factor was associated with lower EC and higher NA (transdiagnostic risks). Several specific risks replicated in both samples after controlling for co-occurring symptoms via the p factor: internalizing was associated with higher NA and lower PA, lower EC related to externalizing problems

    Maternal Depressive Symptoms Predict General Liability in Child Psychopathology

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    Objective: The current study examines how maternal depressive symptoms relate to child psychopathology when structured via the latent bifactor model of psychopathology, a new organizational structure of psychopathological symptoms consisting of a general common psychopathology factor (p-factor) and internalizing- and externalizing-specific risk. Method: Maternal report of depressive symptoms (Beck Depression Inventory – II) and child psychopathological symptoms (Child Behavior Checklist and Children’s Behavior Questionnaire) were provided by 554 mother-child pairs. Children in the sample were 7.7 years old on average (SD = 1.35, range = 5–11 years), and were 49.8% female, 46% Latinx, and 67% White, 6% Black, 5% Asian/Pacific Islander, and 21% multiracial. Results: Maternal depressive symptoms were positively associated with the child p-factor but not with the internalizing- or externalizing-specific factors. We did not find evidence of sex/gender or race/ethnicity moderation when using latent factors of psychopathology. Consistent with past research, maternal depressive symptoms were positively associated with internalizing and externalizing composite scores on the Child Behavior Checklist. Conclusions: Findings suggest that maternal depressive symptoms are associated with transdiagnostic risk for broad child psychopathology (p-factor). Whereas the traditional Achenbach-style approach of psychopathological assessment suggests that maternal depressive symptoms are associated with both child internalizing and externalizing problems, the latent bifactor model suggests that these associations may be accounted for by risk pathways related to the p-factor rather than internalizing or externalizing specific risk. We discuss clinical and research implications of using a latent bifactor structure of psychopathology to understand how maternal depression may impact children’s mental health

    Infant Hedonic/Anhedonic Processing Index (HAPI-Infant): Assessing Infant Anhedonia and Its Prospective Association with Adolescent Depressive Symptoms

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    Background Anhedonia, an impairment in the motivation for or experience of pleasure, is a well-established transdiagnostic harbinger and core symptom of mental illness. Given increasing recognition of early life origins of mental illness, we posit that anhedonia should, and could, be recognized earlier if appropriate tools were available. However, reliable diagnostic instruments prior to childhood do not currently exist. Methods We developed an assessment instrument for anhedonia/reward processing in infancy, the Infant Hedonic/Anhedonic Processing Index (HAPI-Infant). Exploratory factor and psychometric analyses were conducted using data from 6- and 12-month-old infants from two cohorts (N = 188, N = 212). Then, associations were assessed between infant anhedonia and adolescent self-report of depressive symptoms. Results The HAPI-Infant (47-items), exhibited excellent psychometric properties. Higher anhedonia scores at 6 (r = 0.23, p \u3c .01) and 12 months (r = 0.19, p \u3c .05) predicted elevated adolescent depressive symptoms, and these associations were stronger than for established infant risk indicators such as negative affectivity. Subsequent analyses supported the validity of short (27-item) and very short (12-item) versions of this measure. Limitations The primary limitations of this study are that the HAPI-Infant awaits additional tests of generalizability and of its ability to predict clinical diagnosis of depression. Conclusions The HAPI-Infant is a novel, psychometrically strong diagnostic tool suitable for recognizing anhedonia during the first year of life with strong predictive value for later depressive symptoms. In view of the emerging recognition of increasing prevalence of affective disorders in children and adolescents, the importance of the HAPI-Infant in diagnosing anhedonia is encouraging. Early recognition of anhedonia could target high-risk individuals for intervention and perhaps prevention of mental health disorders
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