3,402 research outputs found
U.S. East Coast Trough Indices at 500 hPa and New England Winter Climate Variability
Using monthly gridded 500-hPa data, two synoptic indices are defined to better understand the principle mechanisms controlling intraseasonal to multiannual winter climate variability in NewEngland (NE). The âtrough axis indexâ (TAI) is created to quantify the mean longitudinal position of the common East Coast pressure trough, and the âtrough intensity indexâ (TII) is calculated to estimate the relative amplitude of this trough at 42.5°N. The TAI and TII are then compared with records for NE regional winter precipitation, temperature, and snowfall with the goal of understanding physical mechanisms linking NE winter climate with regional sea surface temperatures (SST), the North Atlantic Oscillation (NAO), and the PacificâNorth American (PNA) teleconnection pattern. The TAI correlates most significantly with winter precipitation at inland sites, such that a western (eastern)trough axis position is associated with greater (lower) average monthly precipitation. Also, significant correlations between the TAI and both NE regional SSTs and the NAO suggest that longitudinal shifting of the trough is one possible mechanism linking the North Atlantic with NE regional winterclimate variability. The NE winter temperature is significantly correlated with the TII, regional SSTs, and the NAO. While the PNA also correlates with the TII, NE winter climate variables are apparently unrelated to the PNA index
Student Life Transformed: A Post-World War Two Institutional Case Study of St. Francis Xavier University
This paper is an institutional case study of how post-World War II social trends reconfigured Canadian universities and colleges and thus substantially altered the undergraduate experience. The study focuses on the church-related college of St. Francis Xavier University in Antigonish, Nova Scotia. By marshalling a combination of salient documentary, oral, survey, and statistical evidence, the author concludes that critical processes, such as rising enrolments, physical plant expansion, faculty laicization, the campaign for student power, and gradual integration of the sexes transformed key dimensions of student life. Pronounced changes occurred in the sociology of residence life, in student attitudes to institutional authority, in student-faculty relations, in institutional decision-making processes, in gender relations, in program offerings and curricular regulations, in rules governing student social life, and in the role of religion. Consequently, the student who enrolled after the 1960s entered a markedly different institution than the student's predecessor who had been admitted as an undergraduate before 1945. The research demonstrates the value of the close analysis of student life at the local institutional level in the post-war era for understanding the contours of the contemporary undergraduate experience.Cette Ă©tude traite de l'impact de la sociĂ©tĂ© canadienne de l'aprĂšs- Seconde Guerre mondiale sur les Ă©tudiantes et Ă©tudiants de l'UniversitĂ© St. Francis Xavier, une fondation religieuse situĂ©e Ă Antigonish, en Nouvelle-Ecosse. Cet article montre, Ă l'aide de statistiques, d'interviews, et de documents d'archives, de quelles façons l'ajout de nouveaux Ă©difices, le processus de sĂ©cularisation du personnel enseignant, la croissance dĂ©mographique du corps Ă©tudiant et sa quĂȘte d'un certain pouvoir ont transformĂ© en profondeur l'essence mĂȘme de l'expĂ©rience universitaire. Les Ă©tudiantes et Ă©tudiants ont alors envisagĂ© sous un oeil tout autre leurs relations avec les autoritĂ©s de l'institution, leurs professeurs, leurs camarades de sexe opposĂ©, de mĂȘme que leur vie en rĂ©sidence, leurs choix de programmes scolaires et la place de la religion dans leur vie. En consĂ©quence, l'Ă©tudiante ou l'Ă©tudiant qui dĂ©bute ses Ă©tudes au dĂ©but des annĂ©es soixante-dix entre Ă une universitĂ© qui ne ressemble guĂšre Ă celle de l'annĂ©e 1945. Une Ă©tude dĂ©taillĂ©e de la vie Ă©tudiante rĂ©vĂšle ainsi les contours de l'expĂ©rience universitaire au premier cycle
Graduate Sessions 9: Keller Easterling
Keller Easterling is an architect, professor, urbanist, and writer whose books Enduring Innocence: Global Architecture and Its Political Masquerades and Organization Space: Landscapes, Highways and Houses in America offer original and provocative conflations of spatial theory and contemporary design
A search for starlight reflected from HD 75289 b
We have used a doppler tomographic analysis to conduct a deep search for the
starlight reflected from the planetary companion to HD 75289. In 4 nights on
VLT2/UVES in January 2003, we obtained 684 high resolution echelle spectra with
a total integration time of 26 hours. We establish an upper limit on the
planet's geometric albedo p < 0.12 (to the 99.9% significance level) at the
most probable orbital inclination i ~ 60 degrees, assuming a grey albedo, a
Venus-like phase function and a planetary radius R_p = 1.6 R_Jup. We are able
to rule out some combinations of the predicted planetary radius and atmospheric
albedo models with high, reflective cloud decks.Comment: 5 pages, 5 figures, MNRAS accepted 12 Oct 200
X-ray Emission From Nearby M-dwarfs: the Super-saturation Phenomenon
A rotation rate and X-ray luminosity analysis is presented for rapidly
rotating single and binary M-dwarf systems. X-ray luminosities for the majority
of both single & binary M-dwarf systems with periods below days
(equatorial velocities, V 6 km~s) are consistent with the
current rotation-activity paradigm, and appear to saturate at about
of the stellar bolometric luminosity. The single M-dwarf data show tentative
evidence for the super-saturation phenomenon observed in some ultra-fast
rotating ( 100 km~s) G & K-dwarfs in the IC 2391, IC 2602 and Alpha
Persei clusters. The IC 2391 M star VXR60b is the least X-ray active and most
rapidly rotating of the short period (P 2 days) stars considered
herein, with a period of 0.212 days and an X-ray activity level about 1.5 sigma
below the mean X-ray emission level for most of the single M-dwarf sample. For
this star, and possibly one other, we cautiously believe that we have
identified the first evidence of super-saturation in M-dwarfs. If we are wrong,
we demonstrate that only M-dwarfs rotating close to their break up velocities
are likely to exhibit the super-saturation effect at X-ray wavelengths.Comment: 12 pages, 4 figures, accepted by MNRA
Assessment of the Geometric Interaction Between the Lotus Transcatheter Aortic Valve Prosthesis and the Native Ventricular Aortic Interface by 320-Multidetector Computed Tomography
AbstractObjectivesThis study sought to assess the geometric interaction between the Lotus Valve System transcatheter aortic prosthesis (Boston Scientific, Natick, Massachusetts) and the native aortoventricular interface using multidetector computed tomography (MDCT).BackgroundThe interaction between transcatheter aortic valve prostheses and native anatomy is variable, although potentially predictable. The Lotus transcatheter device uses a novel mechanical means of expansion, the effect of which on native anatomic geometry has not previously been described.MethodsForty patients treated with the Lotus prosthesis were enrolled. The patients underwent 320-MDCT imaging before and after implantation. Prosthesis dimensions and relevant interaction parameters, including circularity and expansion, were assessed. The degree of paraprosthetic regurgitation (PAR) and prosthesis gradient were measured by transthoracic echocardiography at the same time points.ResultsThe mean baseline annular eccentricity index (EI) was 0.21 ± 0.06 and left ventricular outflow tract EI was 0.31 ± 0.09. The deployed prostheses had high rates of circularity with a mean EI across all device segments of 0.06 ± 0.04. In noncircular device deployment, an EI >0.1 was identified in 25% of prostheses and was associated with greater native annular eccentricity at baseline compared with circular devices (0.24 ± 0.04 vs. 0.19 ± 0.06; p = 0.01). The median percent of expansion was 97.5 ± 3.8% in the inflow portion of the prosthesis. Twenty-five percent of prostheses were <90% expanded in at least 1 segment with a numerical, but not statistically significant, association between oversizing and underexpansion. No correlation was found between device underexpansion and the mean transprosthesis gradient or between noncircularity and PAR.ConclusionsThe Lotus prosthesis results in nearly full device expansion and circularization of the native basal plane. Awareness of the anatomic interaction between this unique device and the native architecture may help in the formulation of appropriate device-specific sizing algorithms
Porcine vas deferens luminal pH is acutely increased by systemic xylazine administration
Data are accumulating to demonstrate that pH regulation in the male reproductive tract has a vital role in modulating sperm cell fertilizing capacity and, therefore, male fertility. Bicarbonate uptake by sperm cells is required for the achievement of motility levels required for fertilization. Vas deferens epithelial cells can carry out measurable bicarbonate secretion, but the available literature to date reports that the vas deferens luminal content is typically acidic. This study aimed to determine pH in the boar vas deferens lumen and whether modulatory mechanisms exist for regulation of pH in this compartment of the male reproductive tract. A fiber-optic pH probe was used to assess pH in the vas deferens of anesthetized adult boars. The mean pH, derived from multiple measurements at variable positions along the vas deferens lumen, was 7.39 ± 0.09. Furthermore, administration of xylazine, an alpha-2 adrenergic receptor agonist, rapidly (< 10 min) alkalinized the vas deferens lumen in most cases. Since the duct was transected proximal to the site of measurements, the observations rule out the possibility that alkalinization resulted from secretion in more proximal portions of the duct. These results indicate that the boar vas deferens lumen can be alkaline, and suggest that porcine vas deferens epithelia increase net bicarbonate secretion in vivo, following systemic alpha-2 adrenergic stimulation. This secretory response greatly changes the luminal environment to which sperm cells are exposed, which will initiate or enhance motility, and is expected to modulate male fertility
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