1,595 research outputs found
Interoperability in the GENESIS 3.0 Software Federation : the NEURON Simulator as an Example
Š 2013 Cornelis et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Poster presented at CNS 2013Non peer reviewe
The transport of nutrient-rich Indian Ocean water through the Red Sea and into coastal reef systems
Driven by upwelling-favorable monsoon winds, nutrient-rich Gulf of Aden Intermediate Water (GAIW) enters the Red Sea from the Indian Ocean each summer. Hydrographic and velocity data acquired in autumn 2011 provide the first indication that GAIW is carried rapidly northward along the eastern Red Sea margin in a well-defined subsurface current with speeds \u3e30 cm sâ1. The nutrient-rich (NO2 + NO3 concentrations up to 17 Îźmol lâ1) GAIW overlaps the euphotic zone and appears to fuel enhanced productivity over depths of 35â67 m. GAIW is broadly distributed through the Red Sea, extending northward along the eastern Red Sea boundary to âź24°N and carried across the Red Sea in the circulation of a basin-scale eddy. Of particular significance is the observed incursion of GAIW into coastal areas with dense coral formations, suggesting that GAIW could be an important source of new nutrients to coral reef ecosystems of the Red Sea
Non-Motor Symptoms and Associated Factors in Parkinsonâs Disease Patients in Addis Ababa, Ethiopia: A Multicenter Cross-Sectional Study
BACKGROUND: Non-motor symptoms (NMSs) of Parkinsonâs disease (PD) were often overlooked and less studied. Little is known about NMSs in Ethiopia. The aim of the study was to determine the prevalence of NMSs and associated factors.METHODS: A multi-center cross-sectional observational study was conducted. NMS questionnaire was used to screen for the NMSs. Both descriptive and analytical statistics were used to analyze the data.RESULTS: Total of 123 PD patients with median of 4 years were investigated. The mean age of PD patients was 62.9 years. The mean age of PD onset was 58.3 years. In 23.6% the age of onset was below age 50. Males accounted 72.4%. Majority of the patients were on Levodopa alone and 31.7% were on levodopa plus trihexyphenidyl. Longer duration of illness was associated with frequent occurrence of NMSs. Constipation was the commonest NMS (78%), followed by urinary urgency (67.5%) and nocturia (63.4%). An unexplained pain was reported by 45.5%, cognitive impairment (45.5%), and sleep disturbance was reported by 45.5% of the study participants. Neurophysciatric symptoms were reported by small proportion of the patients. Lower monthly earning was associated with swallowing problem, unexplained weight change, and lighheadness.CONCLUSION: The prevalence of NMS was high among PD patients in Ethiopia. Constipation was the commonest NMS. Longer duration of illness was associated with frequent occurrence of NMSs. Lower monthly earning was associated with swallowing problem, unexplained weight change, and lighheadness
Hierarchical galaxy formation and substructure in the Galaxy's stellar halo
We develop an explicit model for the formation of the stellar halo from
tidally disrupted, accreted dwarf satellites in the cold dark matter (CDM)
framework, focusing on predictions testable with the Sloan Digital Sky Survey
(SDSS) and other wide-field surveys. Subhalo accretion and orbital evolution
are calculated using a semi-analytic approach within the Press-Schechter
formalism. Motivated by our previous work, we assume that low-mass subhalos (v
< 30 km/s) can form significant populations of stars only if they accreted a
substantial fraction of their mass before the epoch of reionization. With this
assumption, the model reproduces the observed velocity function of galactic
satellites in the Local Group, solving the ``dwarf satellite problem'' without
modifying the popular LCDM cosmology. The disrupted satellites yield a stellar
distribution with a total mass and radial density profile consistent with those
observed for the Milky Way stellar halo. Most significantly, the model predicts
the presence of many large-scale, coherent substructures in the outer halo.
These substructures are remnants of individual, tidally disrupted dwarf
satellite galaxies. Substructure is more pronounced at large galactocentric
radii because of the smaller number density of tidal streams and the longer
orbital times. This model provides a natural explanation for the coherent
structures in the outer stellar halo found in the SDSS commissioning data, and
it predicts that many more such structures should be found as the survey covers
more of the sky. The detection (or non-detection) and characterization of such
structures could eventually test variants of the CDM scenario, especially those
that aim to solve the dwarf satellite problem by enhancing satellite
disruption.Comment: 12 pages, 8 figures, Submitted to Ap
Radio and Millimeter Monitoring of Sgr A*: Spectrum, Variability, and Constraints on the G2 Encounter
We report new observations with the Very Large Array, Atacama Large
Millimeter Array, and Submillimeter Array at frequencies from 1.0 to 355 GHz of
the Galactic Center black hole, Sagittarius A*. These observations were
conducted between October 2012 and November 2014. While we see variability over
the whole spectrum with an amplitude as large as a factor of 2 at millimeter
wavelengths, we find no evidence for a change in the mean flux density or
spectrum of Sgr A* that can be attributed to interaction with the G2 source.
The absence of a bow shock at low frequencies is consistent with a
cross-sectional area for G2 that is less than cm. This
result fits with several model predictions including a magnetically arrested
cloud, a pressure-confined stellar wind, and a stellar photosphere of a binary
merger. There is no evidence for enhanced accretion onto the black hole driving
greater jet and/or accretion flow emission. Finally, we measure the millimeter
wavelength spectral index of Sgr A* to be flat; combined with previous
measurements, this suggests that there is no spectral break between 230 and 690
GHz. The emission region is thus likely in a transition between optically thick
and thin at these frequencies and requires a mix of lepton distributions with
varying temperatures consistent with stratification.Comment: Accepted for publication in Ap
On the Origins of Starburst and Post-Starburst Galaxies in Nearby Clusters
HST WFPC2 images in B (F450W) and I (F814W) have been obtained for three
starburst (SB) and two post-starburst (PSB) galaxies in the Coma cluster, and
for three such galaxies in the cluster DC2048-52. V (F555W) and I images for an
additional PSB galaxy in Coma have been extracted from the archive. Seven of
these galaxies were previously classified as E/S0 on the basis of ground-based
images, one as Sa, and the other as an irregular.
The HST images reveal these SB/PSB galaxies to be heterogeneous in
morphology. Nevertheless a common theme is that many of them, especially the SB
galaxies, tend to have centralized spiral structure that appears simply as a
bright ``bulge''on ground-based images. In addition, while some PSB galaxies
exhibit distinct spiral structure, on the whole they have smoother morphologies
than the SB galaxies. The morphologies and luminosity profiles are generally
consistent with substantial starbursts in the form of centralized spiral
structure (the SB galaxies) which fade into smoother morphologies (the PSB
galaxies), with lingering spectroscopic evidence for past central starbursts.
An important point is that the PSB galaxies retain disks, i.e, they have not
evolved into spheroidal systems.Comment: 32 pages, 10 figures including 3 jpg images. To appear in the January
1999 Astronomical Journa
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