2,395 research outputs found
Studies of charmed baryons at LHCb
We report a search for the doubly charmed baryon through the
decay , using a data sample
corresponding to an integrated luminosity of of
collisions at . In the mass range
3300-3800 no significant signal is observed. Upper limits
at confidence level are set on , the ratio of the production cross
section of the times the relevant branching fraction over the
cross section, as a function of the mass and
lifetime. The largest upper limits on over the investigated mass range are
for a lifetime of and
for a lifetime of .Comment: Article to appear in the proceedings of The 6th International
Workshop on Charm Physics (CHARM 2013
Characterising sand and gravel deposits using electrical resistivity tomography (ERT) : case histories from England and Wales
Electrical Resistivity Tomography (ERT) is a rapidly developing geophysical imaging technique that is now widely
used to visualise subsurface geological structure, groundwater and lithological variations. It is being increasingly used
in environmental and engineering site investigations, but despite its suitability and potential benefits, ERT has yet to
be routinely applied by the minerals industry to sand and gravel deposit assessment and quarry planning. The
principal advantages of ERT for this application are that it is a cost-effective non-invasive method, which can provide
2D or 3D spatial models of the subsurface throughout the full region of interest. This complements intrusive sampling
methods, which typically provide information only at discrete locations. Provided that suitable resistivity contrasts are
present, ERT has the potential to reveal mineral and overburden thickness and quality variations within the body of
the deposit.
Here we present a number of case studies from the UK illustrating the use of 2D and 3D ERT for sand and gravel
deposit investigation in a variety of geological settings. We use these case studies to evaluate the performance of ERT,
and to illustrate good practice in the application of ERT to deposit investigation. We propose an integrated approach
to site investigation and quarry planning incorporating both conventional intrusive methods and ERT
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An Unruptured Anterior Communicating Artery Aneurysm with Bilateral Infraoptic Anterior Cerebral Arteries. Case Report and Review of the Literature
Variations of the anterior cerebral artery-anterior communicating artery complex are commonly identified in aneurysm surgery. An infraoptic course of the anterior cerebral artery is exceedingly rare. Robison first described this anomaly from an anatomic dissection in 1959. A unilateral anomalous infraoptic anterior cerebral artery is more common than anomalies of bilateral infraoptic anterior cerebral arteries. We present the case of an unruptured aneurysm at the anterior communicating artery in a patient with bilateral infraoptic anterior cerebral arteries, identified by computed tomography angiography and verified during surgery. Implications for aneurysm formation and surgical treatment are discussed
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Is There a Role for Treating Inflammation in Moyamoya Disease?: A Review of Histopathology, Genetics, and Signaling Cascades
Moyamoya disease is a slowly progressing steno-occlusive condition affecting the cerebrovasculature. Affecting the terminal internal carotid arteries (ICA) and there branches, bilaterally, a resulting in a fine vascular network in the base of the brain to allow for compensation of the stenosed vessels. While there is obvious evidence of the involvement of inflammatory proteins in the condition, this has historically not been acknowledged as a causal factor. Here we describe the fundamental histopathology, genetics, and signaling cascades involved in moyamoya and debate whether these factors can be linked as causal factor for the condition or whether they are simply a secondary result of the ischemia described in the condition. A particular focus has been placed on the multitude of signaling cascades linked to the condition as these are viewed as having the greatest therapeutic potential. As such we hope to draw some novel insight into potential diagnostic and therapeutic inflammatory targets in the condition
Seismic topographic scattering in the context of GW detector site selection
In this paper, we present a calculation of seismic scattering from irregular
surface topography in the Born approximation. Based on US-wide topographic
data, we investigate topographic scattering at specific sites to demonstrate
its impact on Newtonian-noise estimation and subtraction for future
gravitational-wave detectors. We find that topographic scattering at a
comparatively flat site in Oregon would not pose any problems, whereas
scattering at a second site in Montana leads to significant broadening of wave
amplitudes in wavenumber space that would make Newtonian-noise subtraction very
challenging. Therefore, it is shown that topographic scattering should be
included as criterion in the site-selection process of future low-frequency
gravitational-wave detectors.Comment: 16 pages, 7 figure
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Intra-arterial Onyx Embolization of Vertebral Body Lesions
While Onyx embolization of cerebrospinal arteriovenous shunts is well-established, clinical researchers continue to broaden applications to other vascular lesions of the neuraxis. This report illustrates the application of Onyx (eV3, Plymouth, MN) embolization to vertebral body lesions, specifically, a vertebral hemangioma and renal cell carcinoma vertebral body metastatic lesion
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Middle Meningeal Artery Arising from the Basilar Artery
Various anomalies for the origin of the middle meningeal artery (MMA) have been described in the literature. However, origin of the MMA from the basilar trunk is an extremely rare variant. We report on a 54-year-old female who presented with frequent headaches; magnetic resonance imaging showed a right parietal meningioma. The abnormal origin of the middle meningeal artery from the basilar artery was diagnosed by angiography performed for preoperative embolization of the tumor. We report on the case with a review of the embryologic basis, possible explanations for this aberrant origin, and its clinical implications
Fourier, Gauss, Fraunhofer, Porod and the Shape from Moments Problem
We show how the Fourier transform of a shape in any number of dimensions can
be simplified using Gauss's law and evaluated explicitly for polygons in two
dimensions, polyhedra three dimensions, etc. We also show how this combination
of Fourier and Gauss can be related to numerous classical problems in physics
and mathematics. Examples include Fraunhofer diffraction patterns, Porods law,
Hopfs Umlaufsatz, the isoperimetric inequality and Didos problem. We also use
this approach to provide an alternative derivation of Davis's extension of the
Motzkin-Schoenberg formula to polygons in the complex plane.Comment: 21 pages, no figure
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Glioblastoma Mimicking an Arteriovenous Malformation
Abnormal cerebral vasculature can be a manifestation of a vascular malformation or a neoplastic process. We report the case of a patient with angiography-negative subarachnoid hemorrhage (SAH) who re-presented 3 years later with a large intraparenchymal hemorrhage. Although imaging following the intraparenchymal hemorrhage was suggestive of arteriovenous malformation, the patient was ultimately found to have an extensive glioblastoma associated with abnormal tumor vasculature. The case emphasizes the need for magnetic resonance imaging to investigate angiography-negative SAH in suspicious cases to rule out occult etiologies, such as neoplasm. We also discuss diagnostic pitfalls when brain tumors are associated with hemorrhage and abnormal vasculature
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