Evidence that widespread star formation may be underway in G0.253+016, "The Brick"

Image cubes of differential column density as a function of dust temperature are constructed for Galactic Centre molecular cloud G0.253+0.016 ("The Brick") using the recently described PPMAP procedure. The input data consist of continuum images from the Herschel Space Telescope in the wavelength range 70-500 $\mu$m, supplemented by previously published interferometric data at 1.3 mm wavelength. While the bulk of the dust in the molecular cloud is consistent with being heated externally by the local interstellar radiation field, our image cube shows the presence, near one edge of the cloud, of a filamentary structure whose temperature profile suggests internal heating. The structure appears as a cool ($\sim 14$ K) tadpole-like feature, $\sim 6$ pc in length, in which is embedded a thin spine of much hotter ($\sim$ 40-50 K) material. We interpret these findings in terms of a cool filament whose hot central region is undergoing gravitational collapse and fragmentation to form a line of protostars. If confirmed, this would represent the first evidence of widespread star formation having started within this cloud.Comment: 5 pages, 4 figures; accepted for publication in MNRAS Letter

Riparian vegetation classification from airborne laser scanning data with an emphasis on cottonwood trees

The high point density of airborne laser mapping systems enables achieving a detailed description of geographic objects and the terrain. Growing experience indicates, however, that extracting useful information directly from the data can be difficult. In this study, small-footprint lidar data were used to differentiate between young, mature, and old cottonwood trees in the San Pedro River Basin near Benson, Arizona, USA. The lidar data were acquired in June 2003, using the Optech Incorporated ALTM 1233 (Optech Incorporated, Toronto, Ont.), during flyovers conducted at an altitude of 750 m. The lidar data were preprocessed to create a two-band image of the study site: a high-accuracy canopy altitude model band, and a near-infrared intensity band. These lidar-derived images provided the basis for supervised classification of cottonwood age categories, using a maximum likelihood algorithm. The results of classification illustrate the potential of airborne lidar data to differentiate age classes of cottonwood trees for riparian areas quickly and accurately. © 2006, Taylor & Francis Group, LLC. All rights reserved

School Finance Systems and Their Responsiveness to Performance Pressures: A Case Study of Texas

Details the mechanisms of and influences on the state's school finance system, changes caused by increased performance pressures, local officials' ability to allocate resources as deemed appropriate, and obstacles to linking resources to student learning

School Finance Systems and Their Responsiveness to Performance Pressures: A Case Study of North Carolina

Details the mechanisms of and influences on the state's school finance system, changes caused by increased performance pressures, local officials' views on alternative allocation of resources, and obstacles to linking resources to student learning

Detailed gravimetric geoid confirmation of short wavelength features of sea surface topography detected by the Skylab S-193 altimeter in the Atlantic Ocean

A detailed gravimetric geoid was computed for the Northwest Atlantic Ocean and Caribbean Sea area in support of the calibration and evaluation of the GEOS-C altimeter. This geoid, computed on a 15 ft. x 15 ft. grid was based upon a combination of surface gravity data with the GSFC GEM-6 satellite derived gravity data. A comparison of this gravimetric geoid with 10 passes of SKYLAB altimeter data is presented. The agreement of the two data types is quite good with the differences generally less than 2 meters. Sea surface manifestations of numerous short wavelength (approximately 100 km) oceanographic features are now indicated in the gravimetric geoid and are also confirmed by the altimetry data

Geologic applications of thermal inertia image using HCMM data

The author has identified the following significant results. Comparison of a simulated HCMM image of the Pisgah Crater, California test site obtained from aircraft data with an image generated from the preliminary satellite data tape of the area indicates that the HCMM satellite data appears much as predicted by the simulation

First Lunar Occultation Results from the 2.4 m Thai National Telescope equipped with ULTRASPEC

The recently inaugurated 2.4\,m Thai National Telescope (TNT) is equipped, among other instruments, with the ULTRASPEC low-noise, frame-transfer EMCCD camera. At the end of its first official observing season, we report on the use of this facility to record high time resolution imaging using small detector subarrays with sampling as fast as several $10^2$\,Hz. In particular, we have recorded lunar occultations of several stars which represent the first contribution to this area of research made from South-East Asia with a telescope of this class. Among the results, we discuss an accurate measurement of $\alpha$~Cnc, which has been reported previously as a suspected close binary. Attempts to resolve this star by several authors have so far met with a lack of unambiguous confirmation. With our observation we are able to place stringent limits on the projected angular separation (<0\farcs003) and brightness ($\Delta{\rm m} > 5$) of a putative companion. We also present a measurement of the binary {HR~7072}, which extends considerably the time coverage available for its yet undetermined orbit. We discuss our precise determination of the flux ratio and projected separation in the context of other available data. We conclude by providing an estimate of the performance of ULTRASPEC at TNT for lunar occultation work. This facility can help to extend the lunar occultation technique in a geographical area where no comparable resources were available until now.Comment: Accepted for publication in Astronomical Journa

The Grassmannian Sigma Model in SU(2) Yang-Mills Theory

Spin-charge separation in pure SU(2) Yang-Mills theory was recently found to involve the dynamics of an O(3) non-linear sigma model and, seemingly, a Grassmannian non-linear sigma model. In this article we explicitly construct the Grassmannian sigma model of the form appearing in the the spin-charge separated SU(2) theory through a quaternionic decomposition of the manifold, thus verifying its relevance in this context. The coupling between this model and the O(3) non-linear sigma model is further commented upon.Comment: 11 pages, undergraduate research project; version published in J. Phys.

Development of colon cancer after liver transplantation for primary sclerosing cholangitis associated with ulcerative colitis

Between February 26, 1981, and July 30, 1987, 36 patients underwent orthotopic liver transplantation for primary sclerosing cholangitis associated with ulcerative colitis. Three of the 36 recipients died within 3 mo because of graft nonfunction or surgical complications. The other 33 (92%) lived for at least 1 yr. Two of the 33 died after 12 and 14 mo, respectively, of recurrent cholangiocarcinoma that was not diagnosed before transplantation. Four other patients died of recurrent liver failure (three cases) or immunoblastic sarcoma (one case) after 14, 21, 36 and 44 mo. Twenty‐seven (75%) of the patients are still alive 23 to 81 mo after transplantation. Two patients have been diagnosed as having colorectal cancer 11 and 21 mo respectively, after transplantation, for an overall incidence of 5.6% (2 of 36) and a corrected incidence of 6.5% (2 of 31) if the three early deaths and two later deaths caused by cholangiocarcinomas are excluded. It is not known whether colorectal malignancies were present but undetected at the time of transplantation or whether they developed afterward. It is clear that patients who undergo liver transplantation for primary sclerosing cholangitis associated with ulcerative colitis should have careful follow‐up of the colon, including colonoscopy and multiple biopsies of the colorectal mucosa. Whether proctocolectomy should be considered prophylactically after liver transplantation is an unresolved issue.(HEPATOLOGY 1990;11:477–480.) Copyright © 1990 American Association for the Study of Liver Disease