2,042 research outputs found
Testing the Empirical Shock Arrival Model using Quadrature Observations
The empirical shock arrival (ESA) model was developed based on quadrature
data from Helios (in-situ) and P-78 (remote-sensing) to predict the Sun-Earth
travel time of coronal mass ejections (CMEs) [Gopalswamy et al. 2005a]. The ESA
model requires earthward CME speed as input, which is not directly measurable
from coronagraphs along the Sun-Earth line. The Solar Terrestrial Relations
Observatory (STEREO) and the Solar and Heliospheric Observatory (SOHO) were in
quadrature during 2010 - 2012, so the speeds of Earth-directed CMEs were
observed with minimal projection effects. We identified a set of 20 full halo
CMEs in the field of view of SOHO that were also observed in quadrature by
STEREO. We used the earthward speed from STEREO measurements as input to the
ESA model and compared the resulting travel times with the observed ones from
L1 monitors. We find that the model predicts the CME travel time within about
7.3 hours, which is similar to the predictions by the ENLIL model. We also find
that CME-CME and CME-coronal hole interaction can lead to large deviations from
model predictions.Comment: 17 pages, 4 figures, 3 table
Regional similarities in the distributions of well yield from crystalline rocks in Fennoscandia
Well yields from Precambrian and Palaeozoic bedrock in Norway, Sweden and Finland exhibit very
similar and approximately log-normal distributions: all three data sets exhibit a median yield of
600–700 L hr-1, despite the differences in climate and lithology. This similarity is tentatively reflected
on a larger geographical scale by a meta-analysis of the international data sets on crystalline rock aquifers from other recently glaciated areas (i.e., without a thick regolith of weathered rock). An heuristic treatment of the Fennoscandian data sets suggests that this median yield is consistent with the following bulk properties of shallow (to c. 70–80 m depth) crystalline bedrock: transmissivity of
0.56 ± 0.30 m2 d-1 (6.4 ± 3.4 x 10-6 m2 s-1) and hydraulic conductivity of around 1.1 (± 0.6) x 10-7 m s-1
A Hierarchical Relationship between the Fluence Spectra and CME Kinematics in Large Solar Energetic Particle Events: A Radio Perspective
We report on further evidence that solar energetic particles are organized by
the kinematic properties of coronal mass ejections (CMEs)[1]. In particular, we
focus on the starting frequency of type II bursts, which is related to the
distance from the Sun where the radio emission starts. We find that the three
groups of solar energetic particle (SEP) events known to have distinct values
of CME initial acceleration, also have distinct average starting frequencies of
the associated type II bursts. SEP events with ground level enhancement (GLE)
have the highest starting frequency (107 MHz), while those associated with
filament eruption (FE) in quiescent regions have the lowest starting frequency
(22 MHz); regular SEP events have intermediate starting frequency (81 MHz).
Taking the onset time of type II bursts as the time of shock formation, we
determine the shock formation heights measured from the Sun center. We find
that the shocks form on average closest to the Sun (1.51 Rs) in GLE events,
farthest from the Sun in FE SEP events (5.38 Rs), and at intermediate distances
in regular SEP events (1.72 Rs). Finally, we present the results of a case
study of a CME with high initial acceleration (~3 km s^-2) and a type II radio
burst with high starting frequency (~200 MHz) but associated with a minor SEP
event. We find that the relation between the fluence spectral index and CME
initial acceleration continues to hold even for this minor SEP event.Comment: 11 pages, 7 figures, 1 table, to appear in Journal of Physics:
Conference Series (JPCS), Proceedings of the 16th Annual International
Astrophysics Conference held in Santa Fe, NM, 201
The Peculiar Behavior of Halo Coronal Mass Ejections in Solar Cycle 24
We report on a remarkable finding that the halo coronal mass ejections (CMEs)
in cycle 24 are more abundant than in cycle 23, although the sunspot number in
cycle 24 has dropped by about 40%. We also find that the distribution of
halo-CME source locations is different in cycle 24: the longitude distribution
of halos is much flatter with the number of halos originating at central
meridian distance >/=60 degrees twice as large as that in cycle 23. On the
other hand, the average speed and the associated soft X-ray flare size are the
same in the two cycles, suggesting that the ambient medium into which the CMEs
are ejected is significantly different. We suggest that both the higher
abundance and larger central meridian longitudes of halo CMEs can be explained
as a consequence of the diminished total pressure in the heliosphere in cycle
24 (Gopalswamy et al. 2014). The reduced total pressure allows CMEs expand more
than usual making them appear as halos.Comment: 12 pages, 5 figures, accepted for publication in the Astrophysical
Journal Letters, April 7, 201
Paternity, erectile function, and health-related quality of life in patients operated for pediatric testicular torsion
Introduction Spermatic cord torsion (SCT) may lead to organ loss and can potentially influence fertility. Long-term effects of SCT are not fully investigated. Objective The purpose was to evaluate paternity rates in adults who have had SCT in childhood and to compare the results to those of a control population. The secondary purposes were to compare paternity rates after testis-preserving surgery with those after orchiectomy and to evaluate erectile function and health-related quality of life (HRQoL). Study design Questionnaires concerning paternity, erectile function (International Index of Erectile Function [IIEF]-5 questionnaire), and HRQoL (15D questionnaire) were mailed to 74 men who had been treated for SCT and to 92 controls treated for testicular appendage torsion in 1977-1995 and who were currently older than 30 years. Results Thirty-five of the 74 (47%) patients with SCT and 58 of the 92 (63%) controls responded. A same-aged control was selected for each patient with SCT. The median age at investigation was 41 (interquatile range [IQR]: 36 to 46) years in the SCT group and 41 (IQR: 38 to 46) years in the control group (p = 0.81). The paternity rate was 23 of 35 (66%) in the SCT group and 26 of 34 (76%) in the control group (p = 0.43). Nine percent of patients and controls suffered from infertility. Of the 30- to 50-year-old patients with SCT, 9 of 16 (56%) had children after orchiectomy, and 13 of 16 (81%), after detorsion (p = 0.25). Significant or moderate erectile dysfunction (IIEF-5 total score Discussion Paternity, erectile function, or HRQoL was not impaired in the general level in the patients with SCT in comparison with controls. Both the modes of treatment, orchiectomy or detorsion, had no significant impact on the results. However, the results cannot be generalized to the individual level. The limitations were a small sample size and inability to investigate maternal factors to the paternity. However, the results are encouraging for the patients and families. Conclusion Paternity rate and HRQoL were similar in patients with SCT and controls. The type of surgery (orchiectomy vs. detorsion) did not affect paternity rates statistically. Moderate or significant erectile dysfunction was rare in both groups.Peer reviewe
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