155 research outputs found
The quest for the solar g modes
Solar gravity modes (or g modes) -- oscillations of the solar interior for
which buoyancy acts as the restoring force -- have the potential to provide
unprecedented inference on the structure and dynamics of the solar core,
inference that is not possible with the well observed acoustic modes (or p
modes). The high amplitude of the g-mode eigenfunctions in the core and the
evanesence of the modes in the convection zone make the modes particularly
sensitive to the physical and dynamical conditions in the core. Owing to the
existence of the convection zone, the g modes have very low amplitudes at
photospheric levels, which makes the modes extremely hard to detect. In this
paper, we review the current state of play regarding attempts to detect g
modes. We review the theory of g modes, including theoretical estimation of the
g-mode frequencies, amplitudes and damping rates. Then we go on to discuss the
techniques that have been used to try to detect g modes. We review results in
the literature, and finish by looking to the future, and the potential advances
that can be made -- from both data and data-analysis perspectives -- to give
unambiguous detections of individual g modes. The review ends by concluding
that, at the time of writing, there is indeed a consensus amongst the authors
that there is currently no undisputed detection of solar g modes.Comment: 71 pages, 18 figures, accepted by Astronomy and Astrophysics Revie
Triorchidism at orchidopexy: a case report
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
The surged faradic stimulation to the pelvic floor muscles as an adjunct to the medical management in children with rectal prolapse
<p>Abstract</p> <p>Background</p> <p>To assess the role of the surged faradic stimulation to the pelvic floor muscles as an adjunct to the conservative management in the children of idiopathic rectal prolapse</p> <p>Methods</p> <p><it>Study design</it>: Prospective</p> <p><it>Setting</it>: Pediatric Surgery Department, Pt BD Sharma, Post Graduate Institute of Medical Sciences, Rohtak</p> <p><it>Subjects</it>: 47 consecutive children with idiopathic rectal prolapse attending the Pediatric Surgery out patient department from July 2005 to June 2006</p> <p><it>Methodology</it>: The information pertaining to duration and the extent of rectal prolapse, predisposing or associated medical conditions, results of local clinical examination were noted. Surged faradic stimulation using modified intraluminal rectal probe, was given on the alternate days. The conventional conservative medical management was also continued. The extent of relief and the number of the sittings of faradic stimulation required were noted at various stages of follow-ups</p> <p><it>Statistical Methods</it>: Mean values between those completely cured and others; poor responders and others were compared with t-test and proportions were compared with Chi square test. The p-value < 0.05 was considered statistically significant.</p> <p>Results</p> <p>The mean number of sittings in the completely cured group (n = <b>28</b>(64%)) was (12.4 ± 7.8) and was comparable with very poor responder (n = 6(13%). There was higher percentage of relief (76%) at the first follow up (at 15 days) in completely cured Vs other (37%) and also the poor responders showed (20%) Vs other (68%) and was statistically significant.</p> <p>Conclusion</p> <p>With use of faradic stimulation, even the long-standing rectal prolapse can be fully cured. The follow up visit at 2 weeks is very important to gauge the likely success of this modality in treatment of the patients with rectal prolapse. Those showing poor response at this stage may require alternative treatment or take a long time to get cured</p
On the centenary of the birth of Francis H. C. Crick – from physics to genetics and neuroscience
Computational Fluid Dynamics Applications to MAVs
Micro air Vehicles (MAVs) are unmanned autonomous flying machines with a linear dimension of about 15 cm gross take off weight approximately 100 g and expected loiter time of the order of about 60 minutes. The requirements of any MAV are its ability to loiter for a long duration and also to effectively maneuver in space overland, in buildings and other confined areas
Serotonin induces long-term depression at corticostriatal synapses.
The striatum has important roles in motor control and action learning and, like many brain regions, receives multiple monoaminergic inputs. We have examined serotonergic modulation of rat and mouse corticostriatal neurotransmission and find that serotonin (5-HT) activates 5-HT1b receptors resulting in a long-term depression (LTD) of glutamate release and striatal output that we have termed 5-HT-LTD. 5-HT-LTD is presynaptically mediated, cAMP pathway-dependent, and inducible by endogenous striatal 5-HT, as revealed by application of a selective 5-HT reuptake inhibitor (SSRI). 5-HT-LTD is mutually occlusive with dopamine/endocannabinoid-dependent LTD, suggesting that these two forms of LTD act on the same corticostriatal terminals. Thus, serotonergic and dopaminergic mechanisms exist that may interact to persistently sculpt corticostriatal circuits, potentially influencing action learning and striatal-based disorders
Ensemble encoding of action speed by striatal fast-spiking interneurons
Striatal fast-spiking interneurons (FSIs) potently inhibit the output neurons of the striatum and, as such, powerfully modulate action learning. Through electrical synaptic coupling, FSIs are theorized to temporally coordinate their activity. This has important implications for their ability to temporally summate inhibition on downstream striatal projection neurons. While some in vivo single-unit electrophysiological recordings of putative FSIs support coordinated firing, others do not. Moreover, it is unclear as to what aspect of action FSIs encode. To address this, we used in vivo calcium imaging of genetically identified FSIs in freely moving mice and applied machine learning analyses to decipher the relationship between FSI activity and movement. We report that FSIs exhibit ensemble activity that encodes the speed of action sub-components, including ambulation and head movements. These results suggest FSI population dynamics fit within a Hebbian model for ensemble inhibition of striatal output guiding action
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