142 research outputs found
The Period Changes of the Cepheid RT Aurigae
Observations of the light curve for the 3.7-day Cepheid RT Aur both before
and since 1980 indicate that the variable is undergoing an overall period
increase, amounting to +0.082 +-0.012 s/yr, rather than a period decrease, as
implied by all observations prior to 1980. Superposed on the star's O-C
variations is a sinusoidal trend that cannot be attributed to random
fluctuations in pulsation period. Rather, it appears to arise from light travel
time effects in a binary system. The derived orbital period for the system is P
= 26,429 +-89 days (72.36 +-0.24 years). The inferred orbital parameters from
the O-C residuals differ from those indicated by existing radial velocity data.
The latter imply the most reasonable results, namely a1 sin i = 9.09 (+-1.81) x
10^8 km and a minimum secondary mass of M2 = 1.15 +-0.25 Msun. Continued
monitoring of the brightness and radial velocity changes in the Cepheid are
necessary to confirm the long-term trend and to provide data for a proper
spectroscopic solution to the orbit.Comment: Accepted for publication in PASP (November 2007
Spontaneous dural tear leading to intracranial hypotension and tonsillar herniation in Marfan syndrome: a case report
<p>Abstract</p> <p>Background</p> <p>We describe the case of a 38 year old male with Marfan syndrome who presented with orthostatic headaches and seizures.</p> <p>Case Presentation</p> <p>The patient was diagnosed with Spontaneous Intracranial Hypotension secondary to CSF leaks, objectively demonstrated by MR Myelogram with intrathecal contrast. Epidural autologus blood patch was administered at the leakage site leading to significant improvement.</p> <p>Conclusion</p> <p>Our literature search shows that this is the second reported case of a Marfan patient presenting with symptomatic spontaneous CSF leaks along with tonsillar herniation.</p
Data Fusion and Fuzzy Spatial Relationships for Locating Deep Brain Stimulation Targets in Magnetic Resonance Images
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