933 research outputs found
Significance of the pericardium in human subjects: Effects on left ventricular volume, pressure and ejection
To assess the effect of the pericardium, left ventricular systolic function and diastolic compliance were studied in 15 patients before and after pericardiotomy during coronary artery surgery. Using first pass radionuclide angiography, curves for left ventricular systolic function (stroke work versus end-diastolic volume) and a measure of diastolic compliance (pulmonary capillary wedge pressure versus end-diastolic volume) were generated by changing body position to alter venous return. Left ventricular end-diastolic volume ranged from 41 to 111 ml/m2and pulmonary capillary wedge pressure from 0 to 24 mm Hg.No significant changes were found in blood pressure (150/83 to 148/82 mm Hg), heart rate (66.7 to 67.1 beats/min), cardiac index (2.38 to 2.41 liters/min per m2), ejection fraction (0.56 to 0.54), end-systolic volume index (31.4 to 32.2 ml/m2), end-diastolic volume index (65.9 to 69.5 ml/m2) or pulmonary capillary wedge pressure (7.5 to 7.3 mm Hg). The pericardium did not affect the curves relating stroke work and end-diastolic volume or those relating pulmonary capillary wedge pressure and end-diastolic volume. Thus, when filling pressure and volume are normal or only moderately elevated, the pericardium does not appear to affect left ventricular systolic function or diastolic compliance in patients
Dimming the Lights: 2D Simulations of Deflagrations of Hybrid C/O/Ne White Dwarfs using FLASH
The dimmest and most numerous outlier of the Type Ia supernova population,
Type Iax events, is increasingly being found in the results of observational
campaigns. There is currently no single accepted model to describe these
events. This 2D study explores the viability of modeling Type Iax events as a
hybrid C/O/Ne white dwarf progenitor undergoing a deflagration using the
multi-physics software FLASH. This hybrid was created using the stellar
evolution code MESA, and its C-depleted core and mixed structure have
demonstrated lower yields than traditional C/O progenitors in previous
deflagration-to-detonation studies. To generate a sample, 30 "realizations" of
this simulation were performed, the only difference being the shape of the
initial matchhead used to start the deflagration. As consistent with earlier
work, these realizations produce the familiar hot dense bound remnant
surrounded by sparse ejecta. Our results indicate the majority of the star
remains unburned (~70%) and bound (>90%). Our realizations produce total ejecta
yields on the order of 10 - 10 solar masses, ejected Ni
yields on the order of 10 - 10 solar masses, and ejecta kinetic
energies on the order of 10 - 10 ergs. Compared to yields
inferred from recent observations of the dimmest Type Iax events - SN 2007qd,
SN 2008ha, SN 2010ae, SN 2019gsc, SN 2019muj, SN 2020kyg, and SN 2021fcg - our
simulation produces comparable Ni yields, but too-small total yields and
kinetic energies. Reignition of the remnant is also seen in some realizations.Comment: 43 pages, 15 figures, 4 tables. To be published in Ap
Effects of traumatic brain injury on cognitive functioning and cerebral metabolites in HIV-infected individuals.
We explored the possible augmenting effect of traumatic brain injury (TBI) history on HIV (human immunodeficiency virus) associated neurocognitive complications. HIV-infected participants with self-reported history of definite TBI were compared to HIV patients without TBI history. Groups were equated for relevant demographic and HIV-associated characteristics. The TBI group evidenced significantly greater deficits in executive functioning and working memory. N-acetylaspartate, a putative marker of neuronal integrity, was significantly lower in the frontal gray matter and basal ganglia brain regions of the TBI group. Together, these results suggest an additional brain impact of TBI over that from HIV alone. One clinical implication is that HIV patients with TBI history may need to be monitored more closely for increased risk of HIV-associated neurocognitive disorder signs or symptoms
Incorporating Concepts of Nanotechnology into the Materials Science and Engineering Classroom and Laboratory
The National Science Foundation-supported Materials Research Science and Engineering Center (MRSEC) on Nanostructured Materials and Interfaces at the University of Wisconsin – Madison has an extensive and highly successful education and outreach effort. One theme of this effort is the development of instructional materials based on cutting-edge research in nanoscale science and engineering. Nanotechnology examples, such as light emitting diodes (LEDs), shape memory alloys, amorphous metals, and ferrofluids, illustrate interdisciplinary research that provides connections among materials science, chemistry, physics, and engineering. They also highlight the tools of nanotechnology, such as scanning probe microscopy, electron microscopy, self-assembly, x-ray diffraction, and chemical vapor deposition, associated with the preparation and characterization of nanostructured materials. These and other nanotechnology concepts are illustrated with video demonstrations in a web-based resource called the Nanoworld Cineplex, which contains movies of experiments and demonstrations that can be brought into the classroom. Numerous experiments are also available in the Nanotechnology Lab Manual, which can be used as either a virtual laboratory or as a web-based video lab manual. These resources for using nanotechnology to teach fundamental materials science and engineering principles are available at
Analysis of retinoids by high-performance liquid chromatography using programmed gradient separation
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24984/1/0000411.pd
Dall’Europa a Milano, da Milano all’Europa : a 250 anni da "Dei delitti e delle pene"
In occasione dei 250 anni dalla pubblicazione del trattato "Dei delitti e delle pene" , l'articolo ricostruisce alcuni momenti della vita dell'Accademia dei Pugni, anche in rapporto alle fasi di elaborazione del libro di Cesare Beccaria. Si propongono inoltre considerazioni sulla circolazione dell'opera e in particolare sulla diffusione che in Europa hanno avuto il trattato e, di conseguenza, le soluzioni espressive di quella prosa argomentativa
Seeing the way: visual sociology and the distance runner's perspective
Employing visual and autoethnographic data from a two‐year research project on distance runners, this article seeks to examine the activity of seeing in relation to the activity of distance running. One of its methodological aims is to develop the linkage between visual and autoethnographic data in combining an observation‐based narrative and sociological analysis with photographs. This combination aims to convey to the reader not only some of the specific subcultural knowledge and particular ways of seeing, but also something of the runner's embodied feelings and experience of momentum en route. Via the combination of narrative and photographs we seek a more effective way of communicating just how distance runners see and experience their training terrain. The importance of subjecting mundane everyday practices to detailed sociological analysis has been highlighted by many sociologists, including those of an ethnomethodological perspective. Indeed, without the competence of social actors in accomplishing these mundane, routine understandings and practices, it is argued, there would in fact be no social order
A dual-chamber method for quantifying the effects of atmospheric perturbations on secondary organic aerosol formation from biomass burning emissions
Biomass burning (BB) is a major source of atmospheric pollutants. Field and laboratory studies indicate that secondary organic aerosol (SOA) formation from BB emissions is highly variable. We investigated sources of this variability using a novel dual-smog-chamber method that directly compares the SOA formation from the same BB emissions under two different atmospheric conditions. During each experiment, we filled two identical Teflon smog chambers simultaneously with BB emissions from the same fire. We then perturbed the smoke with UV lights, UV lights plus nitrous acid (HONO), or dark ozone in one or both chambers. These perturbations caused SOA formation in nearly every experiment with an average organic aerosol (OA) mass enhancement ratio of 1.78 ± 0.91 (mean ± 1σ). However, the effects of the perturbations were highly variable ranging with OA mass enhancement ratios ranging from 0.7 (30% loss of OA mass) to 4.4 across the set of perturbation experiments. There was no apparent relationship between OA enhancement and perturbation type, fuel type, and modified combustion efficiency. To better isolate the effects of different perturbations, we report dual-chamber enhancement (DUCE), which is the quantity of the effects of a perturbation relative to a reference condition. DUCE values were also highly variable, even for the same perturbation and fuel type. Gas measurements indicate substantial burn-to-burn variability in the magnitude and composition of SOA precursor emissions, even in repeated burns of the same fuel under nominally identical conditions. Therefore, the effects of different atmospheric perturbations on SOA formation from BB emissions appear to be less important than burn-to-burn variability
First-year Sloan Digital Sky Survey-II (SDSS-II) Supernova Results: Hubble Diagram and Cosmological Parameters
We present measurements of the Hubble diagram for 103 Type Ia supernovae
(SNe) with redshifts 0.04 < z < 0.42, discovered during the first season (Fall
2005) of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. These data
fill in the redshift "desert" between low- and high-redshift SN Ia surveys. We
combine the SDSS-II measurements with new distance estimates for published SN
data from the ESSENCE survey, the Supernova Legacy Survey, the Hubble Space
Telescope, and a compilation of nearby SN Ia measurements. Combining the SN
Hubble diagram with measurements of Baryon Acoustic Oscillations from the SDSS
Luminous Red Galaxy sample and with CMB temperature anisotropy measurements
from WMAP, we estimate the cosmological parameters w and Omega_M, assuming a
spatially flat cosmological model (FwCDM) with constant dark energy equation of
state parameter, w. For the FwCDM model and the combined sample of 288 SNe Ia,
we find w = -0.76 +- 0.07(stat) +- 0.11(syst), Omega_M = 0.306 +- 0.019(stat)
+- 0.023(syst) using MLCS2k2 and w = -0.96 +- 0.06(stat) +- 0.12(syst), Omega_M
= 0.265 +- 0.016(stat) +- 0.025(syst) using the SALT-II fitter. We trace the
discrepancy between these results to a difference in the rest-frame UV model
combined with a different luminosity correction from color variations; these
differences mostly affect the distance estimates for the SNLS and HST
supernovae. We present detailed discussions of systematic errors for both
light-curve methods and find that they both show data-model discrepancies in
rest-frame -band. For the SALT-II approach, we also see strong evidence for
redshift-dependence of the color-luminosity parameter (beta). Restricting the
analysis to the 136 SNe Ia in the Nearby+SDSS-II samples, we find much better
agreement between the two analysis methods but with larger uncertainties.Comment: Accepted for publication by ApJ
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