3,694 research outputs found
Prospectus, February 11, 1972
FAREWELL DR. JAMES; Black History Week; Parkland Has Five In County Board Primary; A.A.U.W. Presents Scholarships; Parkland Students Provide Leadership In Community Scouting Program; Technical-Physics Workshop at Parkland; New Refund Policy Not Effective Until Fall \u2772; The Editor\u27s View: Boy, Am I Mad!; Letters to the Editor; Illinois Grant; What\u27s Going On; Counselor\u27s Corner: ISU Admissions, Open House at U of I College of Pharmacy, U of I Colleges Hold Visitation; 1971-72 Directory; Parkland Notices: Baha\u27i Invite, Smog Clinic, Nursing Students!, McKendree College; Hell Fire.....And Snow Storm!; Kevin On Environment; Orpheus Reborn: My Mirror, A Castle; Mrs. Brotherson Speaks; What They\u27re Reading On Campuses; Reflections; Fear of Night And a Graveyard; Special Appointments For Veterans; Black Genesis; Live! Vida!; Kankakee Gets MOCKed; hart Beat; Cobra Basketball Record; IM Basketball Standings; Parkland Roars Past Wabash 117-87; Cobras Bomb Joliet; Wrestlers (5-5) Pin Millikenhttps://spark.parkland.edu/prospectus_1972/1011/thumbnail.jp
Quantification of hemodynamic changes induced by virtual placement of multiple stents across a wide -necked Basilar trunk aneurysm
OBJECTIVE: The porous intravascular stents that are currently available may not cause
complete aneurysm thrombosis and may therefore fail to provide durable protection
against aneurysm rupture when used as a sole treatment modality. The goal of this study
was to quantify the effects of porous stents on aneurysm hemodynamics using computational fluid dynamics.
METHODS: The geometry of a wide-necked saccular basilar trunk aneurysm was reconstructed from a patient’s computed tomographic angiography images. Three commercial stents (Neuroform2; Boston Scientific/Target, San Leandro, CA; Wingspan; Boston
Scientific, Fremont, CA; and Vision; Guidant Corp., Santa Clara, CA) were modeled.
Various combinations of one to three stents were virtually conformed to fit into the vessel lumen and placed across the aneurysm orifice. An unstented aneurysm served as a
control. Computational fluid dynamics analysis was performed to calculate the hemodynamic parameters considered important in aneurysm pathogenesis and thrombosis
for each of the models.
RESULTS: The complex flow pattern observed in the unstented aneurysm was suppressed by stenting. Stent placement lowered the wall shear stress in the aneurysm,
and this effect was increased by additional stent deployment. Turnover time was moderately increased after single- and double-stent placement and markedly increased after
three stents were placed. The influence of stent design on hemodynamic parameters
was more significant in double-stented models than in other models.
CONCLUSION: Aneurysm hemodynamic parameters were significantly modified
by placement of multiple stents. Because the associated modifications may be helpful as well as harmful in terms of rupture risk, use of this technique requires careful
consideration
Handedness Influences Intermanual Transfer in Chimpanzees (\u3cem\u3ePan troglodytes\u3c/em\u3e) But Not Rhesus Monkeys (\u3cem\u3eMacaca mulatta\u3c/em\u3e)
Intermanual transfer refers to an effect whereby training one hand to perform a motor task improves performance in the opposite untrained hand. We tested the hypothesis that handedness facilitates intermanual transfer in two nonhuman primate species: rhesus monkeys (N = 13) and chimpanzees (N = 52). Subjects were grouped into one of four conditions: (1) left-handers trained with the left (dominant) hand; (2) left-handers trained with the right (non-dominant) hand; (3) right-handers trained with the left (non-dominant) hand; and (4) right-handers trained with the right (dominant) hand. Intermanual transfer was measured using a task where subjects removed a Life Savers® candy (monkeys) or a washer (chimpanzees) from metal shapes. Transfer was measured with latency by comparing the average time taken to solve the task in the first session with the trained hand compared to the first session with the untrained hand. Hypotheses and predictions were derived from three models of transfer: access: benefit training with non-dominant hand; proficiency: benefit training with dominant hand; and cross-activation: benefit irrespective of trained hand. Intermanual transfer (i.e., shorter latency in untrained hand) occurred regardless of whether monkeys trained with the dominant hand or non-dominant hand, supporting the cross-activation model. However, transfer was only observed in chimpanzees that trained with the dominant hand. When handedness groups were examined separately, the transfer effect was only significant for right-handed chimpanzees, partially supporting the proficiency model. Findings may be related to neurophysiological differences in motor control as well as differences in handedness patterning between rhesus monkeys and chimpanzees
Dual black holes in merger remnants. I: linking accretion to dynamics
We study the orbital evolution and accretion history of massive black hole
(MBH) pairs in rotationally supported circumnuclear discs up to the point where
MBHs form binary systems. Our simulations have high resolution in mass and
space which, for the first time, makes it feasible to follow the orbital decay
of a MBH either counter- or co-rotating with respect to the circumnuclear disc.
We show that a moving MBH on an initially counter-rotating orbit experiences an
"orbital angular momentum flip" due to the gas-dynamical friction, i.e., it
starts to corotate with the disc before a MBH binary forms. We stress that this
effect can only be captured in very high resolution simulations. Given the
extremely large number of gas particles used, the dynamical range is
sufficiently large to resolve the Bondi-Hoyle-Lyttleton radii of individual
MBHs. As a consequence, we are able to link the accretion processes to the
orbital evolution of the MBH pairs. We predict that the accretion rate is
significantly suppressed and extremely variable when the MBH is moving on a
retrograde orbit. It is only after the orbital angular momentum flip has taken
place that the secondary rapidly "lights up" at which point both MBHs can
accrete near the Eddington rate for a few Myr. The separation of the double
nucleus is expected to be around ~10 pc at this stage. We show that the
accretion rate can be highly variable also when the MBH is co-rotating with the
disc (albeit to a lesser extent) provided that its orbit is eccentric. Our
results have significant consequences for the expected number of observable
double AGNs at separations of <100 pc.Comment: 8 pages, 4 figures, revised version accepted to MNRA
Morphology parameters for intracranial aneurysm rupture risk assessment
OBJECTIVE—The aim of this study is to identify image-based morphological parameters that
correlate with human intracranial aneurysm (IA) rupture.
METHODS—For 45 patients with terminal or sidewall saccular IAs (25 unruptured, 20 ruptured),
three-dimensional geometries were evaluated for a range of morphological parameters. In addition
to five previously studied parameters (aspect ratio, aneurysm size, ellipticity index, nonsphericity
index, and undulation index), we defined three novel parameters incorporating the parent vessel
geometry (vessel angle, aneurysm [inclination] angle, and [aneurysm-to-vessel] size ratio) and
explored their correlation with aneurysm rupture. Parameters were analyzed with a two-tailed
independent Student's t test for significance; significant parameters (P < 0.05) were further examined
by multivariate logistic regression analysis. Additionally, receiver operating characteristic analyses
were performed on each parameter.
RESULTS—Statistically significant differences were found between mean values in ruptured and
unruptured groups for size ratio, undulation index, nonsphericity index, ellipticity index, aneurysm
angle, and aspect ratio. Logistic regression analysis further revealed that size ratio (odds ratio, 1.41;
95% confidence interval, 1.03−1.92) and undulation index (odds ratio, 1.51; 95% confidence interval,
1.08−2.11) had the strongest independent correlation with ruptured IA. From the receiver operating
characteristic analysis, size ratio and aneurysm angle had the highest area under the curve values of
0.83 and 0.85, respectively.
CONCLUSION—Size ratio and aneurysm angle are promising new morphological metrics for IA
rupture risk assessment. Because these parameters account for vessel geometry, they may bridge the
gap between morphological studies and more qualitative location-based studies
Molecular Gas in Redshift 6 Quasar Host Galaxies
We report our new observations of redshifted carbon monoxide emission from
six z~6 quasars, using the PdBI. CO (6-5) or (5-4) line emission was detected
in all six sources. Together with two other previous CO detections, these
observations provide unique constraints on the molecular gas emission
properties in these quasar systems close to the end of the cosmic reionization.
Complementary results are also presented for low-J CO lines observed at the GBT
and the VLA, and dust continuum from five of these sources with the SHARC-II
bolometer camera at the CSO. We then present a study of the molecular gas
properties in our combined sample of eight CO-detected quasars at z~6. The
detections of high-order CO line emission in these objects indicates the
presence of highly excited molecular gas, with estimated masses on the order of
10^10 M_sun within the quasar host galaxies. No significant difference is found
in the gas mass and CO line width distributions between our z~6 quasars and
samples of CO-detected quasars and submillimeter galaxies.
Most of the CO-detected quasars at z~6 follow the far infrared-CO luminosity
relationship defined by actively star-forming galaxies at low and high
redshifts. This suggests that ongoing star formation in their hosts contributes
significantly to the dust heating at FIR wavelengths. The result is consistent
with the picture of galaxy formation co-eval with supermassive black hole
(SMBH) accretion in the earliest quasar-host systems. We investigate the black
hole--bulge relationships of our quasar sample, using the CO dynamics as a
tracer for the dynamical mass of the quasar host. The results place important
constraints on the formation and evolution of the most massive SMBH-spheroidal
host systems at the highest redshift.Comment: 34 pages, 8 figures, accepted for publication in Ap
Sedimentation in an artificial lake -Lake Matahina, Bay of Plenty
Lake Matahina, an 8 km long hydroelectric storage reservoir, is a small (2.5 km2), 50 m deep, warm monomictic, gorge-type lake whose internal circulation is controlled by the inflowing Rangitaiki River which drains a greywacke and acid volcanic catchment. Three major proximal to distal subenvironments are defined for the lake on the basis of surficial sediment character and dominant depositional process: (a) fluvial-glassy, quartzofeld-spathic, and lithic gravel-sand mixtures deposited from contact and saltation loads in less than 3 m depth; (b) (pro-)deltaic-quartzofeldspathic and glassy sand-silt mixtures deposited from graded and uniform suspension loads in 3-20 m depth; and (c) basinal-diatomaceous, argillaceous, and glassy silt-clay mixtures deposited from uniform and pelagic suspension loads in 20-50 m depth. The delta face has been prograding into the lake at a rate of 35-40 m/year and vertical accretion rates in pro-delta areas are 15-20 cm/year. Basinal deposits are fed mainly from river plume dispersion involving overflows, interflows, and underflows, and by pelagic settling, and sedimentation rates behind the dam have averaged about 2 cm/year. Occasional fine sand layers in muds of basinal cores attest to density currents or underflows generated during river flooding flowing the length of the lake along a sublacustrine channel marking the position of the now submerged channel of the Rangitaiki River
Recommended from our members
High-speed photodetector for plasma diagnostics
Recent progress in four different classes of high-speed photodetectors are reviewed with emphasis on parameters of importance in plasma diagnostics. Two types of biplanar vacuum photodiodes are compared, the ITT F4014 and the Hamamatsu 1328. A conventional photomultiplier, the nine-stage Hamamatsu R928, has been modified to improve its bandwidth. Microchannel plate photomultipliers from two vendors have been studied. Data for the ITT F4126X, ITT F4141, Varian VPM-173, VPM-221, and VPM-225 are summarized. A hybrid photomultiplier using a PIN diode for a gain element has also been investigated. The various tubes and types provide very different limitations on system performance
Are chimpanzees really so poor at understanding imperative pointing? Some new data and an alternative view of canine and ape social cognition
There is considerable interest in comparative research on different species’ abilities to respond to human communicative cues such as gaze and pointing. It has been reported that some canines perform significantly better than monkeys and apes on tasks requiring the comprehension of either declarative or imperative pointing and these differences have been attributed to domestication in dogs. Here we tested a sample of chimpanzees on a task requiring comprehension of an imperative request and show that, though there are considerable individual differences, the performance by the apes rival those reported in pet dogs. We suggest that small differences in methodology can have a pronounced influence on performance on these types of tasks. We further suggest that basic differences in subject sampling, subject recruitment and rearing experiences have resulted in a skewed representation of canine abilities compared to those of monkeys and apes
- …