1,002 research outputs found
More on the Narrowing of Impact Broadened Radio Recombination Lines at High Principal Quantum Number
Recently Alexander and Gulyaev have suggested that the apparent decrease in
impact broadening of radio recombination lines seen at high principal quantum
number n may be a product of the data reduction process, possibly resulting
from the presence of noise on the telescope spectra that is not present on the
calculated comparison spectra. This is an interesting proposal. However, there
are serious problems with their analysis that need to be pointed out. Perhaps
the most important of these is the fact that for principal quantum numbers
below n = 200, where the widths are not in question, their processed generated
profile widths do not fit the widths of the processed lines obtained at the
telescope. After processing, the halfwidths of the generated and telescope
profiles must agree below n = 200 if we are to believe that the processed
generated linewidths above n = 200 are meaningful. Theirs do not. Furthermore,
we find that after applying the linewidth reduction factors found by Alexander
and Gulyaev for their noise added profiles to our generated profiles to
simulate their noise adding effect, the processed widths we obtain still do not
come close to explaining the narrowing seen in the telescope lines for n values
in the range 200 < n < 250. It is concluded that what is needed to solve this
mystery is a completely new approach using a different observing technique
instead of simply a further manipulation of the frequency-switched data.Comment: Six pages with 4 figures. Accepted for publication in Astrophysics
and Space Scienc
Sensitive Observations of Radio Recombination Lines in Orion and W51: The Data and Detection of Systematic Recombination Line Blueshifts Proportional to Impact Broadening
Sensitive spectral observations made in two frequency bands near 6.0 and 17.6
GHz are described for Orion and W51. Using frequency switching we were able to
achieve a dynamic range in excess of 10,000 without fitting sinusoidal or
polynomial baselines. This enabled us to detect lines as weak as T\Delta n$ as
high as 25 have been detected in Orion. In the Orion data, where the lines are
stronger, we have also detected a systematic shift in the line center
frequencies proportional to linewidth that cannot be explained by normal
optical depth effects.Comment: 22 pages, 13 figures. Accepted for publication in Astrophysics and
Space Scienc
Arachidonic acid, arachidonic/eicosapentaenoic acid ratio, stearidonic acid and eicosanoids are involved in dietary-induced albinism in Senegal sole (Solea senegalensis)
Senegal sole larvae were fed live prey enriched with different amounts of arachidonic acid (ARA, 20:4n-6) and eicosapentaenoic acid (EPA, 20:5n-3) to re-evaluate the effect of these two fatty acids on flatfish pigmentation. Echium oil, a plant derived oil rich in gamma-linolenic acid (GLA, 18:3n-6) and stearidonic acid (SDA, 18:4n-3) was also used as a component of one of the enrichment emulsions. Although ARA content did not have any effect on growth there was a clear influence on pigmentation that correlated clearly with prostaglandin production. Inclusion of Echium oil, on the contrary, exerted a positive effect on pigmentation rate even though dietary ARA levels were as high as in the other emulsions. The relationships between dietary ARA levels and dietary ARA/EPA ratio, prostaglandin production and pigmentation are discussed
Project Status Report: Ecology and Environment Project
We present here the extended outline and copies of the illustrations used in the Status Report of the IIASA Ecology and Environment Project, presented at Schloss Laxenburg on 21 June 1974.
Section 1., "General Review", is covered in the outline. Section 2., "A Case Study of Ecosystem Management", is the subject of a major monograph now in preparation. Section 3., on Selected Conceptual Developments, is in part documented in IIASA Research Reports RR-73-3 and RR-74-3
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Neoclassical Tearing Modes in Tokamak Fusion Test Reactor Experiments Part 1. Measurements of Magnetic Islands and Delta Prime.
Tearing-type modes are observed in most high-confinement operation regimes in TFTR. Three different methods are used to measure the magnetic island widths: external magnetic coils, internal temperature fluctuation from the electron cyclotron emission (ECE) diagnostic, and an experiment where the plasma major radius is rapidly shifted ("Jog" experiments). A good agreement between the three methods is observed. Numerical and analytic calculations of delta prime (the tearing instability index) are compared with an experimental measurement of delta prime using the tearing-mode eigenfunction mapped from the jog data. The obtained negative delta prime indicates that the observed tearing modes cannot be explained by the classical current-gradient-driven tearing theory
Standard Model CP-violation and Baryon asymmetry
Simply based on CP arguments, we argue against a Standard Model explanation
of the baryon asymmetry of the universe in the presence of a first order phase
transition. A CP-asymmetry is found in the reflection coefficients of quarks
hitting the phase boundary created during the electroweak transition. The
problem is analyzed both in an academic zero temperature case and in the
realistic finite temperature one. The building blocks are similar in both
cases: Kobayashi-Maskawa CP-violation, CP-even phases in the reflection
coefficients of quarks, and physical transitions due to fermion self-energies.
In both cases an effect is present at order in rate. A standard
GIM behaviour is found as intuitively expected. In the finite temperature case,
a crucial role is played by the damping rate of quasi-particles in a hot
plasma, which is a relevant scale together with and the temperature. The
effect is many orders of magnitude below what observation requires, and
indicates that non standard physics is indeed needed in the cosmological
scenario.Comment: 15p, LaTeX (3figs incl.), CERN 93/7081,LPTHE
Orsay-93/48,HUTP-93/A036,HD-THEP-93-4
Bell inequalities and entanglement in solid state devices
Bell-inequality checks constitute a probe of entanglement -- given a source
of entangled particles, their violation are a signature of the non-local nature
of quantum mechanics. Here, we study a solid state device producing pairs of
entangled electrons, a superconductor emitting Cooper pairs properly split into
the two arms of a normal-metallic fork with the help of appropriate filters. We
formulate Bell-type inequalities in terms of current-current cross-correlators,
the natural quantities measured in mesoscopic physics; their violation provides
evidence that this device indeed is a source of entangled electrons.Comment: 4 pages, 1 figur
Evidence that the Bursting Component of the X-ray Radiation From 3C 111 Originates in the PC-Scale Jet
Evidence is presented indicating that the bursting component of the X-ray
radiation detected in the nuclear region of the active radio galaxy 3C 111
comes from the blobs ejected in the pc-scale jet and not from the accretion
disc. After each new outburst the radio flux density associated with it
increases to a peak in ~1 year and then subsides over a period of 1-2 years
with the flux falling off exponentially as the blob moves outward and
dissipates. Similar peaks (bursts) are seen in the X-ray light curve and a
cross-correlation between the two shows a very high correlation with the X-ray
peaks leading the radio peaks by ~100 days. A second cross-correlation, this
time between the radio event start times and the X-ray light curve, also shows
a significant correlation. When this is taken together with the long (~1 yr)
delay between the start of each ejection event and its associated X-ray peak it
indicates that this bursting component of the X-ray flux must be associated
with the ejected blobs in the pc-scale jet and not with the accretion disc.
Because X-ray telescopes do not have the resolution required to resolve the
accretion disc area from the pc-scale jet, this paper is the first to present
observational evidence that can pinpoint the point of origin of at least those
long-timescale X-ray bursts with durations of 1-3 yrs.Comment: 11 pages, 8 Figures. Accepted for publication in Astrophysics and
Space Scienc
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