4,142 research outputs found
Acute complete heart block in dogs
A study has been conducted immediately and up to 18 days after the surgical production of complete heart block in dogs. Immediately after surgery cardiac output, coronary flow, and mean arterial pressure were reduced in rough proportion to the degree of bradycardia. In time, these measures began to return toward preoperative levels. Paralleling the diminished left ventricular work was a diminished left ventricular oxygen consumption with little consequent change in myocardial efficiency. Small rises were detected in central venous pressure. At autopsy, the only unequivocal abnormality was myocardial hypertrophy which became measurable between 2 and 18 days after operation
On the changes in the physical properties of the ionized region around the Weigelt structures in Eta Carinae over the 5.54-yr spectroscopic cycle
We present HST/STIS observations and analysis of two prominent nebular
structures around the central source of Eta Carinae, the knots C and D. The
former is brighter than the latter for emission lines from intermediate or high
ionization potential ions. The brightness of lines from intermediate and high
ionization potential ions significantly decreases at phases around periastron.
We do not see conspicuous changes in the brightness of lines from low
ionization potential (<13.6 eV) that the total extinction towards the Weigelt
structures is that the total extinction towards the Weigelt structures is AsubV
=2/0. that the total extinction towards the Weigelt structures is AV = 2.0.
Weigelt C and D are characterized by an electron density of that the total
extinction towards the Weigelt structures is AV = 2.0. Weigelt C and D are
characterized by an electron density of 10exp6.9 cm-3 that does not
significantly change throughout the orbital cycle. The electron temperature
varies from 5500 K (around periastron) to 7200 K (around apastron). The
relative changes in the brightness of He I lines are well reproduced by the
variations in the electron temperature alone. We found that, at phases around
periastron, the electron temperature seems to be higher for Weigelt C than that
of D. The Weigelt structures are located close to the Homunculus equatorial
plane, at a distance of about 1240 AU from the central source. From the
analysis of proper motion and age, the Weigelt complex can be associated with
the equatorial structure called the Butterfly Nebula surrounding the central
binary system.Comment: 19 pages, 18 figure
aristotle's demonstrative logic
Demonstrative logic, the study of demonstration as opposed to persuasion, is the subject of Aristotle's two-volume Analytics. Many examples are geometrical. Demonstration produces knowledge (of the truth of propositions). Persuasion merely produces opinion. Aristotle presented a general truth-and-consequence conception of demonstration meant to apply to all demonstrations. According to him, a demonstration, which normally proves a conclusion not previously known to be true, is an extended argumentation beginning with premises known to be truths and containing a chain of reasoning showing by deductively evident steps that its conclusion is a consequence of its premises. In particular, a demonstration is a deduction whose premises are known to be true. Aristotle's general theory of demonstration required a prior general theory of deduction presented in the Prior Analytics. His general immediate-deduction-chaining conception of deduction was meant to apply to all deductions. According to him, any deduction that is not immediately evident is an extended argumentation that involves a chaining of intermediate immediately evident steps that shows its final conclusion to follow logically from its premises. To illustrate his general theory of deduction, he presented an ingeniously simple and mathematically precise special case traditionally known as the categorical syllogisti
A systematic review of evidence on the impacts of joint decision-making on community wellbeing - PROTOCOL
First detection of phase-dependent colliding wind X-ray emission outside the Milky Way
After having reported the detection of X-rays emitted by the peculiar system
HD5980, we assess here the origin of this high-energy emission from additional
X-ray observations obtained with XMM-Newton. This research provides the first
detection of apparently periodic X-ray emission from hot gas produced by the
collision of winds in an evolved massive binary outside the Milky Way. It also
provides the first X-ray monitoring of a Luminous Blue Variable only years
after its eruption and shows that the dominant source of the X-rays is not
associated with the ejecta.Comment: 13 pages, 3 figures and 1 table, accepted for publication in ApJ
(letters
Discovery of CH and OH in the -513 km s-1 Ejecta of Eta Carinae
The very massive star, Eta Carinae, is enshrouded in an unusual complex of
stellar ejecta, which is highly depleted in C and O, and enriched in He and N.
This circumstellar gas gives rise to distinct absorption components
corresponding to at least 20 different velocities along the line-of-sight. The
velocity component at -513 kms-1 exhibits very low ionization with
predominantly neutral species of iron-peak elements. Our statistical
equilibrium/photoionization modeling indicates that the low temperature (T =
760 K) and high density (n_H=10^7 cm^-3) of the -513 kms-1 component is
conducive to molecule formation including those with the elements C and O.
Examination of echelle spectra obtained with the Space Telescope Imaging
Spectrograph (STIS) aboard the confirms the model's predictions. The molecules,
H_2, CH, and most likely OH, have been identified in the -513 kms-1 absorption
spectrum. This paper presents the analysis of the HST/STIS spectra with the
deduced column densities for CH, OH and C I, and upper limit for CO. It is
quite extraordinary to see molecular species in a cool environment at such a
high velocity. The sharp molecular and ionic absorptions in this extensively
CNO- processed material offers us a unique environment for studying the
chemistry, dust formation processes, and nucleosynthesis in the ejected layers
of a highly evolved massive star.Comment: tentatively scheduled for the ApJ 1 September 2005, v630, 1 issu
PD-L1 is not constitutively expressed on tasmanian devil facial tumor cells but is strongly upregulated in response to IFN-gamma and can be expressed in the tumor microenvironment
The devil facial tumor disease (DFTD) is caused by clonal transmissible cancers that have led to a catastrophic decline in the wild Tasmanian devil (Sarcophilus harrisii) population. The first transmissible tumor, now termed devil facial tumor 1 (DFT1), was first discovered in 1996 and has been continually transmitted to new hosts for at least 20 years. In 2015, a second transmissible cancer [devil facial tumor 2 (DFT2)] was discovered in wild devils, and the DFT2 is genetically distinct and independent from the DFT1. Despite the estimated 136,559 base pair substitutions and 14,647 insertions/deletions in the DFT1 genome as compared to two normal devil reference genomes, the allograft tumors are not rejected by the host immune system. Additionally, genome sequencing of two sub-strains of DFT1 detected greater than 15,000 single-base substitutions that were found in only one of the DFT1 sub-strains, demonstrating the transmissible tumors are evolving and that generation of neoantigens is likely ongoing. Recent evidence in human clinical trials suggests that blocking PD-1:PD-L1 interactions promotes antitumor immune responses and is most effective in cancers with a high number of mutations. We hypothesized that DFTD cells could exploit the PD-1:PD-L1 inhibitory pathway to evade antitumor immune responses. We developed recombinant proteins and monoclonal antibodies (mAbs) to provide the first demonstration that PD-1 binds to both PD-L1 and PD-L2 in a non-placental mammal and show that PD-L1 is upregulated in DFTD cells in response to IFN-γ. Immunohistochemistry showed that PD-L1 is rarely expressed in primary tumor masses, but low numbers of PD-L1+ non-tumor cells were detected in the microenvironment of several metastatic tumors. Importantly, in vitro testing suggests that PD-1 binding to PD-L1 and PD-L2 can be blocked by mAbs, which could be critical to understanding how the DFT allografts evade the immune system.Andrew S. Flies, A. Bruce Lyons, Lynn M. Corcoran, Anthony T. Papenfuss, James M. Murphy, Graeme W. Knowles, Gregory M. Woods and John D. Haybal
Density of states of a type-II superconductor in a high magnetic field: Impurity effects
We have calculated the density of states of a dirty but
homogeneous superconductor in a high magnetic field. We assume a dilute
concentration of scalar impurities and find how behaves as one
crosses from the weak scattering to the strong scattering limit. At low
energies, for small values of the impurity
concentration and scattering strength. When the disorder becomes stronger than
some critical value, a finite density of states is created at the Fermi
surface. These results are a consequence of the gapless nature of the
quasiparticle excitation spectrum in a high magnetic field.Comment: 20 pages in RevTeX, 4 figures, to appear in Phys. Rev. B (July 1,
1997
Detection of Gamma-ray Emission from the Eta-Carinae Region
We present the results of extensive observations by the gamma-ray AGILE
satellite of the Galactic region hosting the Carina nebula and the remarkable
colliding wind binary Eta Carinae (Eta Car) during the period 2007 July to 2009
January. We detect a gamma-ray source (1AGL J1043-5931) consistent with the
position of Eta Car. If 1AGL J1043-5931 is associated with the Eta Car system
our data provide the long sought first detection above 100 MeV of a colliding
wind binary. The average gamma-ray flux above 100 MeV and integrated over the
pre-periastron period 2007 July to 2008 October is F = (37 +/- 5) x 10-8 ph
cm-2 s-1 corresponding to an average gamma-ray luminosity of L = 3.4 x 10^34
erg s-1 for a distance of 2.3 kpc. We also report a 2-day gamma-ray flaring
episode of 1AGL J1043-5931 on 2008 Oct. 11-13 possibly related to a transient
acceleration and radiation episode of the strongly variable shock in the
system.Comment: 5 pages, 4 figure, accepted for publication in ApJ Letter
Coherence in the Quasi-Particle 'Scattering' by the Vortex Lattice in Pure Type-II Superconductors
The effect of quasi-particle (QP) 'scattering' by the vortex lattice on the
de-Haas van-Alphen oscillations in a pure type-II superconductor is
investigated within mean field,asymptotic perturbation theory. Using a 2D
electron gas model it is shown that, due to a strict phase coherence in the
many-particle correlation functions, the 'scattering' effect in the asymptotic
limit () is much weaker than what is predicted
by the random vortex lattice model proposed by Maki and Stephen, which destroys
this coherence . The coherent many particle configuration is a collinear array
of many particle coordinates, localized within a spatial region with size of
the order of the magnetic length. The amplitude of the magnetization
oscillations is sharply damped just below because of strong
out of phase magnetic oscillations in the superconducting
condensation energy ,which tend to cancel the normal electron oscillations.
Within the ideal 2D model used it is found, however, that because of the
relative smallness of the quartic and higher order terms in the expansion, the
oscillations amplitude at lower fields does not really damp to zero, but only
reverses sign and remains virtually undamped well below . This
conclusion may be changed if disorder in the vortex lattice, or vortex lines
motion will be taken into account. The reduced QP 'scattering' effect may be
responsible for the apparent crossover from a strong damping of the dHvA
oscillations just below to a weaker damping at lower fields observed
experimentally in several 3D superconductors.Comment: 26 pages, Revtex no Figure
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