14,390 research outputs found
The mechanical properties of inconel 718 sheet alloy at 800 deg, 1000 deg, and 1200 deg f
Mechanical properties of Inconel sheet superalloy at very high temperatures for supersonic transpor
The Close Binary Fraction of Dwarf M Stars
We describe a search for close spectroscopic dwarf M star binaries using data from the Sloan Digital Sky Survey to address the question of the rate of occurrence of multiplicity in M dwarfs. We use a template-fitting technique to measure radial velocities from 145,888 individual spectra obtained for a magnitude-limited sample of 39,543 M dwarfs. Typically, the three or four spectra observed for each star are separated in time by less than four hours, but for ~17% of the stars, the individual observations span more than two days. In these cases we are sensitive to large-amplitude radial velocity variations on timescales comparable to the separation between the observations. We use a control sample of objects having observations taken within a four-hour period to make an empirical estimate of the underlying radial velocity error distribution and simulate our detection efficiency for a wide range of binary star systems. We find the frequency of binaries among the dwarf M stars with a < 0.4 AU to be 3%-4%. Comparison with other samples of binary stars demonstrates that the close binary fraction, like the total binary fraction, is an increasing function of primary mass
Irish National Income in 1911 and its Context. ESRI Working Paper No. 63, October 1995
No Abstrac
The unusual distribution of molecular gas and star formation in Arp 140
We investigate the atomic and molecular interstellar medium and star
formation of NGC 275, the late-type spiral galaxy in Arp 140, which is
interacting with NGC 274, an early-type system. The atomic gas (HI)
observations reveal a tidal tail from NGC 275 which extends many optical radii
beyond the interacting pair. The HI morphology implies a prograde encounter
between the galaxy pair approximately 1.5 x 10**8 years ago. The Halpha
emission from NGC 275 indicates clumpy irregular star-formation, clumpiness
which is mirrored by the underlying mass distribution as traced by the Ks-band
emission. The molecular gas distribution is striking in its anti-correlation
with the {HII regions. Despite the evolved nature of NGC 275's interaction and
its barred potential, neither the molecular gas nor the star formation are
centrally concentrated. We suggest that this structure results from stochastic
star formation leading to preferential consumption of the gas in certain
regions of the galaxy. In contrast to the often assumed picture of interacting
galaxies, NGC 275, which appears to be close to merger, does not display
enhanced or centrally concentrated star formation. If the eventual merger is to
lead to a significant burst of star formation it must be preceded by a
significant conversion of atomic to molecular gas as at the current rate of
star formation all the molecular gas will be exhausted by the time the merger
is complete.Comment: 13 paper, accepted my Monthly Notices of the Royal Astronomical
Societ
A question of time or a question of theology: a study of the Easter controversy in the insular church
Time and theology are the twin pillars on which this thesis rests. It will explore how different scriptural interpretations led to theological and computistical differences between the Insular and continental/Roman churches. The Insular Church believed in and strictly adhered to the tradition passed on to them by their "fathers". What were the origins of these traditions and the theology that formed them? To apprehend Easter controversies, whether it is the early Quartodeciman controversy or the controversy in the Insular Church, an understanding of how biblical exegesis and different theological perspectives shaped the minds and hearts of those involved, is necessary. The Exodus story as portrayed in the Old Testament formed the basis for a theological interpretation of the Christian Passover, inheriting from Judaism a rich heritage of images and symbols used and developed in early paschal homilies. To gain insight into this particular theology the writings of those directly involved in the Insular controversy will be explored.
Medieval monasteries distinguished between festal time and ordinary time. It is against this sense of "festalism" and the passionate need to get it right that the dating of Easter is argued. The discussion hinges on a fixed point of reference for the Easter full moon. The cultural sensitivies of the time must be taken into account. To celebrate "out" of time was to break the unity of the Church. More importantly, it raised the question of one's eternal salvation. Monastic life, which strongly influenced the early Irish Church was in a very real sense caught up in the great "drama" enacted between heaven and hell in which the cycle of the Christian year was a vital weapon. To date scholarly research has approached this topic from a medieval historical perspective. It has, however, never been approached from a purely theological stance. Questions regarding the Insular 84-year cycle have occupied scholars over the past one hundred years or so. A review of the literature reveals an advance in understanding the techniques of the computus of the Insular church. The work of Dáibhà Ó CróinÃn is well documented and his findings have considerably enriched the body of knowledge on this question. The discovery in Padua of a latercus provided for the first time an example of an Irish computus. Accompanying this text was the text of the Paschal Canon of Anatolius: this text is essential to an understanding of the Insular computus. Anatolius' contribution was not simply technical but he provides valuable insight into the cosmological considerations behind a theological understanding of the Easter feast as a feast of light
Prolonging assembly through dissociation:A self assembly paradigm in microtubules
We study a one-dimensional model of microtubule assembly/disassembly in which
GTP bound to tubulins within the microtubule undergoes stochastic hydrolysis.
In contrast to models that only consider a cap of GTP-bound tubulin, stochastic
hydrolysis allows GTP-bound tubulin remnants to exist within the microtubule.
We find that these buried GTP remnants enable an alternative mechanism of
recovery from shrinkage, and enhances fluctuations of filament lengths. Under
conditions for which this alternative mechanism dominates, an increasing
depolymerization rate leads to a decrease in dissociation rate and thus a net
increase in assembly.Comment: accepted for publication in Physical Review
The growth of the Roman Catholic training colleges for women in England during the nineteenth and twentieth centuries
This account of the establishment and growth of the Catholic Women's Training Colleges in England has been written to illustrate the efforts of the small and poor Catholic community, beset by- innumerable and apparently unsurmountable problems, to provide women teachers for the schools, which after the establishment of the Catholic Poor School Committee in 1847, they struggled to establish and maintain. The earlier years have been treated in more detail because it was an heroic age of experiment in unfamiliar circumstances, when it was vital for the Catholic Colleges to establish their reputation in the eyes, not only of the Catholic community, but still more in those of the Committee of Council from whom so much of their income came. For the very existence of the Catholic schools depended on the supply of well trained and devoted teachers. There is also for the nineteenth century much first hand material, not hitherto published, in the Reports of the Catholic Poop School Committee, in the Reports of the Committee of Councils and at Mount Pleasant Training College, Liverpool and for the short lived college at the Holy Child Convent, Mayfield, Sussex. The developments of the present century are covered in less detail since by the end of the nineteenth century, the colleges had become part of the established provision for teacher training in this country and the pattern, once laid down was followed in great measure by succeeding foundations, though the history of each college has of course its special fascination and its distinctive features. With the coming of the Three Year Course and the opening of new colleges planned for the early sixties, we may be on the eve of a new heroic age, but that is another story
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