378 research outputs found
Pulse propagation in the pulmonary and systemic arteries
The one-dimensional model of Olufsen (2000) [*] for blood flow in the systemic arteries has been extended and built upon in a number of ways. Firstly, it has been applied to hypotheses of diseases of the systemic circulation, and that of the microcirculation. With a view to better understanding the microcirculation (the smallest vessels of the systemic circulation) and its diseases, the model has been extended to provide predictions of the propagating pressure pulse and flow rate in small arteries.
Secondly, Olufsen’s model has been used as a base upon which to build a model of the pulmonary circulation, incorporating both the pulmonary arterial and venous circulations, with detailed simulations of pressure and flow predicted in the large pulmonary arteries and large pulmonary veins. To this end, a new model has been eveloped to describe a connected network of small arteries and small veins, replacing the small arterial model used as an outflow condition in the original model. A new outflow condition to describe the return of blood from the pulmonary venous system to the left atrium of the heart has also been implemented.
Finally, this new pulmonary model has been applied to various hypotheses as to the causes of diseases and disorders of the pulmonary circulation, providing predictions of pressure and flow in the large pulmonary arteries and veins in both normal and abnormal circumstances, and showing agreement with clinical observations.
[*] M.S. Olufsen at al. Numerical simulation and experimental validation of blood flow in arteries with structured-tree outflow conditions. Ann Biomed Eng, 28:1281–1299, 2000
DETERMINATION OF INTERSTITIAL SOLID-SOLUBILITY LIMIT IN TANTALUM AND IDENTIFICATION OF THE PRECIPITATE PHASES
Solid-solubility limits at 1500, 1000, snd 500/sup o/C for carbon, nitrogen, and oxygen in high-punity tantalum were determined by x-ray lattice- parameter methods. For carbon, the solubility was found to be 0.17 at. % at 1500/sup o/C and less than 0.07 at. % at l00/sup o/C. A nitrogen solubility of 3.70 at. % at l500/sup o/C decreased linearly with temperature to 2.75 at. % at 1000/sup o/C and 1.8 at. % at 500/sup o/C. In the case of oxygen, the solubility was found to be 3.65 at. % at 1500/sup o/C, 1.95 at. % at l0O0/sup o/ C, and 2.5 at. % at 500/sup o/C. The phases Ta/sub 2/, the lowtemperature modificstion of Ta/sub 2/O/sub 5/, and Ta/sub x/N of unknown coznposition hut which has a superlattice structure based upon the oniginsl body-centered-cubic tantalum lattice were identified is the initisl precipitates in the respective systems. (auth
X-ray Periodicity in AGN
Significant (marginal) detections of periodic signals have been recently
reported in 3 (4) Active Galactic Nuclei. Three of the detections were obtained
from long EUVE light curves of moderate-luminosity Seyfert galaxies; the fourth
was discovered in Chandra data from the low-luminosity Seyfert 1 galaxy NGC
4395. When compared with Cyg X-1, I find that the period is related to the
luminosity as rather than the expected one-to-one
relationship. This result might be explained if the QPO is associated with the
inner edge of the optically thick accretion disk, and the inner edge radius
depends on the source luminosity (or black hole mass). A discussion of
uncertainties in the period detection methodology is also discussed.Comment: To appear in From X-ray Binaries to Quasars: Black Hole Accretion on
All Mass Scales, eds. T. J. Maccarone, R. P. Fender, and L. C. Ho (Dordrecht:
Kluwer
United classification of cosmic gamma-ray bursts and their counterparts
United classification of gamma-ray bursts and their counterparts is
established on the basis of measured characteristics: photon energy E and
emission duration T. The founded interrelation between the mentioned
characteristics of events consists in that, as the energy increases, the
duration decreases (and vice versa). The given interrelation reflects the
nature of the phenomenon and forms the E-T diagram, which represents a natural
classification of all observed events in the energy range from 10E9 to 10E-6 eV
and in the corresponding interval of durations from about 10E-2 up to 10E8 s.
The proposed classification results in the consequences, which are principal
for the theory and practical study of the phenomenon.Comment: Keywords Gamma rays: burst
Augmented Reality in Astrophysics
Augmented Reality consists of merging live images with virtual layers of
information. The rapid growth in the popularity of smartphones and tablets over
recent years has provided a large base of potential users of Augmented Reality
technology, and virtual layers of information can now be attached to a wide
variety of physical objects. In this article, we explore the potential of
Augmented Reality for astrophysical research with two distinct experiments: (1)
Augmented Posters and (2) Augmented Articles. We demonstrate that the emerging
technology of Augmented Reality can already be used and implemented without
expert knowledge using currently available apps. Our experiments highlight the
potential of Augmented Reality to improve the communication of scientific
results in the field of astrophysics. We also present feedback gathered from
the Australian astrophysics community that reveals evidence of some interest in
this technology by astronomers who experimented with Augmented Posters. In
addition, we discuss possible future trends for Augmented Reality applications
in astrophysics, and explore the current limitations associated with the
technology. This Augmented Article, the first of its kind, is designed to allow
the reader to directly experiment with this technology.Comment: 15 pages, 11 figures. Accepted for publication in Ap&SS. The final
publication will be available at link.springer.co
BICCO-Net II. Final report to the Biological Impacts of Climate Change Observation Network (BICCO-Net) Steering Group
• BICCO-Net Phase II presents the most comprehensive single assessment of climate change impacts on UK biodiversity to date.
• The results provide a valuable resource for the CCRA 2018, future LWEC report cards, the National Adaptation Programme and other policy-relevant initiatives linked to climate change impacts on biodiversity
Situationally edited empathy: an effect of socio-economic structure on individual choice
Criminological theory still operates with deficient models of the offender as agent, and of social influences on the agent’s decision-making process. This paper takes one ‘emotion’, empathy, which is theoretically of considerable importance in influencing the choices made by agents; particularly those involving criminal or otherwise harmful action. Using a framework not of rational action, but of ‘rationalised action’, the paper considers some of the effects on individual psychology of social, economic, political and cultural structure. It is suggested that the climate-setting effects of these structures promote normative definitions of social situations which allow unempathic, harmful action to be rationalised through the situational editing of empathy. The ‘crime is normal’ argument can therefore be extended to include the recognition that the uncompassionate state of mind of the criminal actor is a reflection of the self-interested values which govern non-criminal action in wider society
Enhanced delivery and detection of terahertz frequency radiation from a quantum cascade laser within dilution refrigerator
We report on significant enhancements to the integration of terahertz (THz) quantum cascade lasers (QCL) and THz detection with a two-dimensional electron gas (2DEG) within a dilution refrigerator obtained by the inclusion of a multi-mesh 6 THz low-pass filter to block IR radiation, a Winston cone to focus light output, and gating the 2DEG for optimised sensitivity. We show that these improvements allow us to obtain a > 2.5 times reduced sample electron temperature (160 mK compared with 430 mK previously), during cyclotron resonance (CR) measurements of a 2DEG under QCL illumination. This opens up a route to performing sub-100 mK experiments using excitation by THz QCLs
Dietary sugar/starches intake and Barrett’s esophagus: a pooled analysis
Barrett’s esophagus (BE) is the key precursor lesion of esophageal adenocarcinoma, a lethal cancer that has increased rapidly in westernized countries over the past four decades. Dietary sugar intake has also been increasing over time, and may be associated with these tumors by promoting hyperinsulinemia. The study goal was to examine multiple measures of sugar/starches intake in association with BE. This pooled analysis included 472 BE cases and 492 controls from two similarly conducted case–control studies in the United States. Dietary intake data, collected by study-specific food frequency questionnaires, were harmonized across studies by linking with the University of Minnesota Nutrient Database, and pooled based on study-specific quartiles. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for age, sex, race, total energy intake, study indicator, body mass index, frequency of gastro-esophageal reflux, and fruit/vegetable intake. In both studies, intake of sucrose (cases vs. controls, g/day: 36.07 vs. 33.51; 36.80 vs. 35.06, respectively) and added sugar (46.15 vs. 41.01; 44.18 vs. 40.68, respectively) were higher in cases than controls. BE risk was increased 79% and 71%, respectively, for associations comparing the fourth to the first quartile of intake of sucrose (ORQ4vs.Q1 = 1.79, 95% CI = 1.07–3.02, Ptrend = 0.01) and added sugar (ORQ4vs.Q1 = 1.71, 95% CI = 1.05–2.80, Ptrend = 0.15). Intake of sweetened desserts/beverages was associated with 71% increase in BE risk (ORQ4vs.Q1 = 1.71, 95% CI = 1.07–2.73, Ptrend = 0.04). Limiting dietary intake of foods and beverages that are high in added sugar, especially refined table sugar, may reduce the risk of developing BE
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