A compact density condensation around L1551-IRS 5: 2.7mm continuum observations with 4" resolution

The dark cloud L1551 contains the best known examples of bipolar molecular outflow. Such outflows are assumed to be driven by winds from young stars embedded in a cloud but the mechanism for collimation of the outflows is still in doubt, though it has been much debated. Among the possibilities put forth to date are intrinsically anisotropic stellar winds, isotropic stellar winds collimated by interstellar toroidal shaped clouds on the order of 10(17) cm in size, or circumstellar disks of order 10(15) cm in size. Because the outflow in L1551 as revealed by the Very Large Array (VLA) cm continuum observations is collimated even at the arc second level it seems as though the stellar wind powering the outflow must either be initially anisotropic or be collimated by something very close to the star, such as a circumstellar disk. We have observed L1551 in the continuum at 2.7 mm with the OVRO millimeter-wave interferometer in the winter of 1983-4 and again, more extensively, in 1985-6. The resulting map shows for the first time direct evidence for a density condensation capable of collimating an initially isotropic flow from IRS 5. This map made from data taken in 1985-6 with projected baselines up to 100 m in length (37k lambda). It has been cleaned and reconstructed with a 4'' gaussian beam. It shows a nearly unresolved source with a suggestion of extension at the 3'' level (assuming a gaussian source shape). The integrated flux density in this map is 170 mJy. A composite spectrum of L1551 is presented which shows that the flux at 2.7 mm is due to the thermal radiation from dust that is also seen at shorter wavelengths. Very little of it can be due to the continuation of the nearly flat cm wavelength spectrum which is assumed to be from thermal bremsstrahlung radiation. The map and spectrum provide strong constraints on the size, temperature, and optical depth of the density condensation surrounding IRS 5

Development of carbon dioxide laser doppler instrumentation detection of clear air turbulence

The analytical, experimental, and developmental aspects of an airborne, pulsed, carbon dioxide laser-optical radar system are described. The laser detects clear air turbulence and performs Doppler measurements of this air-motion phenomenon. Conclusions and recommendations arising from the development of the laser system are presented

Differential Assessment and the Preservation of Open Space

In order to set the stage for the analysis which follows, it is necessary to review the basic contextual framework in which differential assessment operates. Farmers are producers of two entirely different classes of goods for two different markets: agricultural commodities and development sites. The common factor joining these two markets is the farmer\u27s land. When used for the production of agricultural commodities, land has a value which is related to its capitalized economic rent as a factor of production. Its economic rent is determined by such factors as soil quality, topography, distance from the market, access to transportation facilities, level of management including drainage, crop rotation and soil conservation practices, general conditions in local, regional, national and international commodity markets, natural conditions such as drought, and so on. The rate at which economic rent is capitalized is a function of property taxes, capitalization rates of competing investment, and investors\u27 expectations concerning appreciation in land values

Splendors of the Serenissima in a Digital Age: The Master of the Murano Gradual Reconsidered

The Master of the Murano Gradual is one of the most enigmatic illuminators working in early fifteenth-century Venice. The eponymous choir books were commissioned by the Camaldolese monastery of San Mattia a Murano and today comprise a single intact volume in the Kupferstichkabinett in Berlin (MS 78 F.1) and about fifty historiated initials dispersed in twenty-five public and private collections in Europe and the United States. The fragmentary nature of the overall corpus is a central challenge to studying the artist and to understanding the contours of the workshop. This article provides a reassessment of the corpus of work attributed to the Murano Master—including an appendix with provenances of the whereabouts of the series—and makes a case for future collaborations that can build upon digitization efforts that make the fragments available online and upon recent technical analysis into the pigments used by the illuminators. The methodological approach of the authors has been twofold. Firstly, to study each of the fragments and manuscripts in person, and to locate digital assets for as many works as possible with the aim of creating an eventual website or online repository for scholars to consult. Secondly, to investigate codicological features of the individual fragments that have been hitherto overlooked, including the measurement of musical stave heights or blind-ruled lines for song, and the possible relationship between decorated and filigree letters to over one-hundred cuttings with decorated letters that have also been associated with the San Mattia series. Finally, the study also clarifies the dating of the Murano choir books, which were most likely produced in the 1420s

Neurodegeneration: Paying It Off with Sleep

SummaryA new study in fruit flies suggests modulation of neural activity links sleep and Alzheimer’s disease. Both sleep loss and amyloid beta increase neural excitability, which reinforces the accumulation of amyloid beta and shortens lifespan

The development of thirty self-administering and self-scoring elaborative thinking exercises

Thesis (Ed.M.)--Boston Universit