88 research outputs found

    Drift-induced deceleration of Solar Energetic Particles

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    We investigate the deceleration of Solar Energetic Particles (SEPs) during their propagation from the Sun through interplanetary space, in the presence of weak to strong scattering in a Parker spiral configuration, using relativistic full orbit test particle simulations. The calculations retain all three spatial variables describing particles’ trajectories, allowing to model any transport across the magnetic field. Large energy change is shown to occur for protons, due to the combined effect of standard adiabatic deceleration and a significant contribution from particle drift in the direction opposite to that of the solar wind electric field. The latter drift-induced deceleration is found to have a stronger effect for SEP energies than for galactic cosmic rays. The kinetic energy of protons injected at 1 MeV is found to be reduced by between 35 and 90% after four days, and for protons injected at 100 MeV by between 20 and 55%. The overall degree of deceleration is a weak function of the scattering mean free path, showing that, although adiabatic deceleration plays a role, a large contribution is due to particle drift. Current SEP transport models are found to account for drift-induced deceleration in an approximate way and their accuracy will need to be assessed in future work

    Solar Particle Radiation Storms Forecasting and Analysis: The HESPERIA HORIZON 2020 Project and Beyond

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    While it is believed that the acceleration of Solar Energetic Particles (SEPs) is powered by the release of magnetic energy at the Sun, the nature, and location of the acceleration are uncertain, i.e. the origin of the highest energy particles is heavily debated. Information about the highest energy SEPs relies on observations by ground-based Neutron Monitors (NMs). SEPs with energies above 500 MeV entering the Earth’s atmosphere will lead to an increase of the intensities recorded by NMs on the ground, also known as Ground Level Event or Ground Level Enhancement (GLE). A Fokker-Planck equation well describes the interplanetary transport of near relativistic electrons and protons. An NM is an integral counter defined by its yield function. From the observations of the NM network, the additional solar cosmic ray characteristics (intensity, spectrum, and anisotropy) in the energy range ≳ ≳ 500 MeV can be assessed. If the interplanetary magnetic field outside the Earth magnetosphere is known (see Sect. 10.3.2) a computation chain can be set up in order to calculate the count rate increase of an NM for a delta injection at the Sun along the magnetic field line that connects the Sun with the Earth (Sect. 10.3.3). By this computations, we define a set of Green’s functions that can be fitted to an observed GLE to determine the injection time profile. If the latter is compared to remote sensing measurements like radio observations conclusions of the most probable acceleration process can be drawn.</p

    Heliospheric Transport of Neutron-Decay Protons

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    We report on new simulations of the transport of energetic protons originating from the decay of energetic neutrons produced in solar flares. Because the neutrons are fast-moving but insensitive to the solar wind magnetic field, the decay protons are produced over a wide region of space, and they should be detectable by current instruments over a broad range of longitudes for many hours after a sufficiently large gamma-ray flare. Spacecraft closer to the Sun are expected to see orders-of magnitude higher intensities than those at the Earth-Sun distance. The current solar cycle should present an excellent opportunity to observe neutron-decay protons with multiple spacecraft over different heliographic longitudes and distances from the Sun.Comment: 12 pages, 4 figures, to be published in special issue of Solar Physic

    Comprehensive Characterization of Solar Eruptions with Remote and In-Situ Observations, and Modeling: The Major Solar Events on 4 November 2015

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    Solar energetic particles (SEPs) are an important product of solar activity. They are connected to solar active regions and flares, coronal mass ejections (CMEs), EUV waves, shocks, Type II and III radio emissions, and X-ray bursts. These phenomena are major probes of the partition of energy in solar eruptions, as well as for the organization, dynamics, and relaxation of coronal and interplanetary magnetic fields. Many of these phenomena cause terrestrial space weather, posing multiple hazards for humans and their technology from space to the ground. Since particular flares, shocks, CMEs, and EUV waves produce SEP events but others do not, since propagation effects from the low corona to 1 AU appear important for some events but not others, and since Type II and III radio emissions and X-ray bursts are sometimes produced by energetic particles leaving these acceleration sites, it is necessary to study the whole system with a multi-frequency and multi-instrument perspective that combines both in-situ and remote observations with detailed modeling of phenomena. This article demonstrates this comprehensive approach and shows its necessity by analyzing a trio of unusual and striking solar eruptions, radio and X-ray bursts, and SEP events that occurred on 4 November 2015. These events show both strong similarities and differences from standard events and each other, despite having very similar interplanetary conditions and only two flare sites and CME genesis regions. They are therefore major targets for further in-depth observational studies, and for testing both existing and new theories and models. We present the complete suite of relevant observations, complement them with initial modeling results for the SEPs and interplanetary magnetic connectivity, and develop a plausible scenario for the eruptions. Perhaps controversially, the SEPs appear to be reasonably modelled and evidence points to significant non-Parker magnetic fields. Based on the very limited modeling available, we identify the aspects that are and are not understood, and we discuss ideas that may lead to improved understanding of the SEP, radio, and space-weather events

    Wnt receptors, bone mass, and fractures: gene-wide association analysis of LRP5 and LRP6 polymorphisms with replication

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    Objectives. Genes explaining the susceptibility to osteoporosis have not been fully elucidated. Our objective was to explore the association of polymorphisms capturing common variations of the lipoprotein receptor related protein (LRP) 5 and 6 genes, encoding two Wnt receptors, with femoral neck bone mineral density (BMD) and osteoporotic fractures of the spine and the hip. Design. Cross-sectional, case-control and replication genetic association study. Methods. Thirty nine tagging and functional single nucleotide polymorphisms (SNP) were analyzed in a group of 1043 postmenopausal women and 394 women with hip fractures. The results were replicated in a different group of 342 women. Results. Three SNPs of the LRP6 gene were associated with BMD (nominal uncorrected pvalues< 0.05) in the discovery cohort. One showed a significant association after multiple test correction; two of them were also associated in the replication cohort, with a combined standardized mean difference of 0.51 (p=0.009) and 0.65 (p<0.0001) across rs11054704 and rs2302685 genotypes. In the discovery cohort, several LRP5 SNPs were associated with vertebral fractures (odds ratio 0.67; p=0.01), with hip fractures (unadjusted odds ratios between 0.59 and 1.21, p=0.005-0.033, but not significant after multiple test- or age-adjustment), and with height and the projected femoral neck area, but not with BMD. Transcripts of LRP5 and LRP6 were similarly abundant in bone samples. Conclusions. In this study we found common polymorphisms of LRP5 associated with osteoporotic fractures, and polymorphisms of the LRP6 gene associated with BMD, thus suggesting them as likely candidates to contribute explaining the hereditary influence on osteoporosis

    Periodontal disease and some adverse perinatal outcomes in a cohort of low risk pregnant women

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    Objective: To evaluate the association of periodontal disease (PD) in pregnancy with some adverse perinatal outcomes. Method: This cohort study included 327 pregnant women divided in groups with or without PD. Indexes of plaque and gingival bleeding on probing, probing pocket depth, clinical attachment level and gingival recession were evaluated at one periodontal examination below 32 weeks of gestation. The rates of preterm birth (PTB), low birth weight (LBW), small for gestational age (SGA) neonates and prelabor rupture of membranes (PROM) were evaluated using Risk Ratios (95%CI) and Population Attributable Risk Fractions. Results: PD was associated with a higher risk of PTB (RRadj. 3.47 95% CI 1.62-7.43), LBW (RRadj. 2.93 95% CI 1.36-6.34) and PROM (RRadj. 2.48 95% CI 1.35-4.56), but not with SGA neonates (RR 2.38 95% CI 0.93 - 6.10). Conclusions: PD was a risk factor for PT, LBW and PROM among Brazilian low risk pregnant women

    Depression in Primary care: Interpersonal Counseling vs Selective serotonin reuptake inhibitors. The DEPICS Study. A multicenter randomized controlled trial. Rationale and design

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    <p>Abstract</p> <p>Background</p> <p>Depression is a frequently observed and disabling condition in primary care, mainly treated by Primary Care Physicians with antidepressant drugs. Psychological interventions are recommended as first-line treatment by the most authoritative international guidelines but few evidences are available on their efficacy and effectiveness for mild depression.</p> <p>Methods/Design</p> <p>This multi-center randomized controlled trial was conducted in 9 Italian centres with the aim to compare the efficacy of Inter-Personal Counseling, a brief structured psychological intervention, to that of Selective Serotonin Reuptake Inhibitors. Patients with depressive symptoms referred by Primary Care Physicians to psychiatric consultation-liaison services were eligible for the study if they met the DSM-IV criteria for major depression, had a score ≥13 on the 21-item Hamilton Depression Rating Scale, and were at their first or second depressive episode. The primary outcome was remission of depressive symptoms at 2-months, defined as a HDRS score ≤ 7. Secondary outcome measures were improvement in global functioning and recurrence of depressive symptoms at 12-months. Patients who did not respond to Inter-Personal Counseling or Selective Serotonin Reuptake Inhibitors at 2-months received augmentation with the other treatment.</p> <p>Discussion</p> <p>This trial addresses some of the shortcomings of existing trials targeting major depression in primary care by evaluating the comparative efficacy of a brief psychological intervention that could be easily disseminated, by including a sample of patients with mild/moderate depression and by using different outcome measures.</p> <p>Trial registration</p> <p>Australian New Zealand Clinical Trials Registry ACTRN12608000479303</p

    Mental Health in university students in social isolation during the COVID-19 Pandemic. Arequipa, Peru.

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    Introducción: La Pandemia COVID-19, ha tenido impactos negativos en la salud física y mental de las personas, así como las medidas adoptadas por los gobiernos, para prevenir el contagio masivo de la población como el confinamiento, el aislamiento social, el trabajo y educación virtual. Dentro de los afectados por estos cambios, se encontrarían los estudiantes universitarios del área de la salud, que además de estudiar en estas condiciones de pandemia, no han podido hacer sus prácticas de los servicios de salud. Esta situación de exposición al aislamiento, podría afectar la salud mental de los jóvenes estudiantes universitarios. &nbsp;Objetivo: determinar los niveles de depresión, ansiedad y estrés en estudiantes universitarios y su relación con variables sociodemográficas y las características del aislamiento social durante la Pandemia COVID-19.. Métodos:&nbsp;&nbsp;Se realizó un estudio descriptivo, observacional, de corte transversal y cuantitativo, con una muestra de 818 estudiantes universitarios de facultades de ciencias de la salud, mediante el cuestionario autoadministrado DASS-21. Resultados:&nbsp; Los principales hallazgos fueron: una mayor prevalencia en niveles altos (severos y extremadamente severos) en la ansiedad, alcanzado casi a 4 de cada 10 de los evaluados; por otro lado, en depresión y el estrés, 2 de cada 10 de los evaluados, se encontraron en los niveles mencionados. En relación con las variables sociodemográficas, las relacionadas con el COVID-19 y aislamiento social, se hallaron diferencias estadísticamente significativas con el género (mujeres &gt; varones), el haber tenido COVID-19 (Si &gt; No) y vivir con familiares como antes de la pandemia (Si &gt; No) obtuvieron en promedio mayores puntajes en depresión, ansiedad y estrés. Conclusión:&nbsp;Los estudiantes que presentaron mayor depresión, ansiedad y estrés con una diferencia significativa fueron de&nbsp;género femenino, con antecedentes de haber tenido Covid-19, menor contacto con famiiares y haber cumplido con aislamiento social totalAbstractIntroduction: The COVID-19 Pandemic has had negative impacts on the physical and mental health of people, as well as the measures adopted by governments to prevent the massive contagion of the population, such as confinement, social isolation, virtual work, and virtual education. Among those affected by these changes would be university students in the health area who, in addition to studying in these pandemic conditions, have been unable to do their health service practices. This situation of exposure to isolation could affect the mental health of young university students. Objective: To determine the levels of depression, anxiety, and stress in university students, their relationship with sociodemographic variables, and the characteristics of social isolation during the COVID-19 Pandemic. Methods: A descriptive, observational, cross-sectional, and quantitative study was carried out with a sample of 818 university students from health sciences faculties using the DASS-21 self-administered questionnaire. Results: The main findings were a higher prevalence of high levels (severe and highly severe) in anxiety, reaching almost 4 out of 10 of those evaluated; On the other hand, in depression and stress, 2 out of 10 of those evaluated were found at the mentioned levels. Concerning the sociodemographic variables, those related to COVID-19 and social isolation, statistically significant differences were found with gender (women &gt; men), having had COVID-19 (Yes &gt; No), and living with relatives as before. On average, the pandemic (Yes &gt; No) obtained higher scores in depression, anxiety, and stress. Conclusion: The students who presented greater depression, anxiety, and stress with a significant difference were female, with a history of having had Covid-19, less contact with family members, and having complied with total social isolation &nbsp
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