Williams College

About: Williams College is a education organization based out in Williamstown, Massachusetts, United States. It is known for research contribution in the topics: Population & Politics. The organization has 2257 authors who have published 5015 publications receiving 213160 citations. The organization is also known as: Williams.

Increased mesolimbic dopamine binding following chronic haloperidol treatment.

Abstract: It is well documented that chronic neuroleptic treatment creates a dopamine receptor supersensitivity in the striatum. The present study examined the effect of chronic neuroleptic treatment on mesolimbic dopamine receptor binding. Rats received either 0.5mg/kg of haloperidol, 50mg/kg of sodium phenobarbital, or 0.9% saline daily for 21 days. One week following the last injection, the rats were sacrificed and the septi were removed for the 3H-dopamine binding assay. Haloperidol treatment resulted in a 52% increase in 3H-dopamine binding in the septum, whereas phenobarbital treatment caused no significant change.

Morphology and composition of the helix nebula

Abstract: We present new narrowband filter imagery in Hα and [N II] λ6584, along with UV and optical spectrophotometry measurements from 1200 to 9600 A of NGC 7293, the Helix Nebula, a nearby, photogenic planetary nebula of large diameter and low surface brightness. Detailed models of the observable ionized nebula support the recent claim that the Helix is actually a flattened disk whose thickness is roughly one-third its diameter, with an inner region containing hot, highly ionized gas that is generally invisible in narrowband images. The outer visible ring structure is of lower ionization and temperature and is brighter because of a thickening in the disk. We also confirm a central star effective temperature and luminosity of 120,000 K and 100 L☉, and we estimate a lower limit to the nebular mass to be 0.30 M☉. Abundance measurements indicate the following values: He/H=0.12 (± 0.017), O/H=4.60×10-4 (± 0.18), C/O=0.87 (± 0.12), N/O=0.54 (± 0.14), Ne/O=0.33 (± 0.04), S/O=3.22 × 10-3 (± 0.26), and Ar/O=6.74 × 10-3 (± 0.76). Our carbon abundance measurements represent the first of their kind for the Helix Nebula. The S/O ratio that we derive is anomalously low; such values are found in only a few other planetary nebulae. The central star properties, the supersolar values of He/H and N/O, and a solar level of C/O are consistent with a 6.5 M☉ progenitor that underwent three phases of dredge-up and hot bottom burning before forming the planetary nebula.