74,220 research outputs found
Low-Temperature Expansions and Correlation Functions of the Z_3-Chiral Potts Model
Using perturbative methods we derive new results for the spectrum and
correlation functions of the general Z_3-chiral Potts quantum chain in the
massive low-temperature phase. Explicit calculations of the ground state energy
and the first excitations in the zero momentum sector give excellent
approximations and confirm the general statement that the spectrum in the
low-temperature phase of general Z_n-spin quantum chains is identical to one in
the high-temperature phase where the role of charge and boundary conditions are
interchanged. Using a perturbative expansion of the ground state for the Z_3
model we are able to gain some insight in correlation functions. We argue that
they might be oscillating and give estimates for the oscillation length as well
as the correlation length.Comment: 17 pages (Plain TeX), BONN-HE-93-1
TESS unveils the phase curve of WASP-33b. Characterization of the planetary atmosphere and the pulsations from the star
We present the detection and characterization of the full-orbit phase curve
and secondary eclipse of the ultra-hot Jupiter WASP-33b at optical wavelengths,
along with the pulsation spectrum of the host star. We analyzed data collected
by the Transiting Exoplanet Survey Satellite (TESS) in sector 18. WASP-33b
belongs to a very short list of highly irradiated exoplanets that were
discovered from the ground and were later visited by TESS. The host star of
WASP-33b is of delta Scuti-type and shows nonradial pulsations in the
millimagnitude regime, with periods comparable to the period of the primary
transit. These completely deform the photometric light curve, which hinders our
interpretations. By carrying out a detailed determination of the pulsation
spectrum of the host star, we find 29 pulsation frequencies with a
signal-to-noise ratio higher than 4. After cleaning the light curve from the
stellar pulsations, we confidently report a secondary eclipse depth of 305.8
+/- 35.5 parts-per-million (ppm), along with an amplitude of the phase curve of
100.4 +/- 13.1 ppm and a corresponding westward offset between the region of
maximum brightness and the substellar point of 28.7 +/- 7.1 degrees, making
WASP-33b one of the few planets with such an offset found so far. Our derived
Bond albedo, A_B = 0.369 +/- 0.050, and heat recirculation efficiency, epsilon
= 0.189 +/- 0.014, confirm again that he behavior of WASP-33b is similar to
that of other hot Jupiters, despite the high irradiation received from its host
star. By connecting the amplitude of the phase curve to the primary transit and
depths of the secondary eclipse, we determine that the day- and nightside
brightness temperatures of WASP-33b are 3014 +/- 60 K and 1605 +/- 45 K,
respectively. From the detection of photometric variations due to gravitational
interactions, we estimate a planet mass of M_P = 2.81 +/- 0.53 M$_J.Comment: 19 pages, 15 figure
Intensity-intensity correlations as a probe of interferences - under conditions of none in the intensity
The different behaviour of first order interferences and second order
correlations are investigated for the case of two coherently excited atoms. For
intensity measurements this problem is equivalent to Young's double slit
experiment and was investigated in an experiment by Eichmann et al. [Phys. Rev.
Lett. 70, 2359 (1993)] and later analyzed in detail by Itano et al. [Phys. Rev.
A 57, 4176 (1998)]. Our results show that in cases where the intensity
interferences disappear the intensity-intensity correlations can display an
interference pattern with a visibility of up to 100%. The contrast depends on
the polarization selected for the detection and is independent of the strength
of the driving field. The nonclassical nature of the calculated
intensity-intensity correlations is also discussed.Comment: 14 pages, 2 figure
Dibenzo[a,g]quinolizin-8-ones: synthesis, estrogen receptor affinities, and cytostatic activity
A number of acetoxy-substituted dibenzo[a,g]quinolizin-8-ones were
synthesized by the reaction of 1-oxoisoquinolines with substituted homophthalic acid
anhydride. All of the derivatives with acetoxy groups in positions 3 and 10 bind to the
estrogen receptor. Relative binding affinities (RBA) ranged from 1.8 to 5.6 (estradiol:
RBA = 100) when the substituent at C-6 was a short alkyl group. Introduction of
additional oxygen functions in the 2- and/or 11-position decreased binding affinities.
Analyses of the enantiomers of 6-methyl (6b) and 6-ethyl (6c) derivatives revealed that
the receptor binding is mainly due to one optical isomer (e.g. (-)-6b, 9.9; (+)-6b, 0.6).
In hormone-sensitive human MCF-7 breast cancer cells, compounds with one acetoxy
group in each aromatic ring strongly inhibited cellular growth. Despite marked differences
in receptor affinity, the enantiomers displayed similar activities in this cell
culture. In hormone-independent MDA-MB 231 mammary tumor cells, only a weak
cytostatic effect was recorded at 10-5 M. In the immature mouse uterine weight test,
minimal estrogenic activity was observed. At higher doses, a significant anti-estrogenic
effect became evident. It is assumed that the estrogen antagonism is responsible for
the specific cytostatic effect in MCF-7 breast cancer cells
First Law of Black Saturn Thermodynamics
The physical version and equilibrium state version of the first law of
thermodynamics for a black object consisting of n-dimensional charged
stationary axisymmetric black hole surrounded by black rings, the so-called
black Saturn was derived. The general setting for our derivation is
n-dimensional dilaton gravity with p + 1 strength form fields.Comment: 9 pages, RevTex, to be published in Phys.Rev.D1
Investigation on the influence of nematophagous fungi as feed additive on nematode infection risk of sheep and goats on pasture
Gastrointestinal nematodes in small ruminants cause high economic losses. Thus on most farms anthelmintic treatment is required. In response to increasing problems with anthelmintic resistance, biological control, for example the use of nematophagous fungi, has received significant attention. The aim of this study was to investigate the effect of Duddingtonia flagrans orally applied to small ruminants on natural infection with gastrointestinal nematodes in a field study in Northern Germany.
20 goats and 20 sheep were fed daily for 3 months with 5x105 spores of D. flagrans per kg bodyweight. Differences in body weight, faecal egg count and larval development in faeces and on pasture in comparison with same-sized control groups were analysed. After 3 months the control goats showed significantly higher mean faecal egg count than the fungus-fed group. No significant difference was found between the two sheep groups. The maximum in larval reduction in faeces was 81.3 % in the sheep groups and 67.9 % in the goat groups (not significant). At the end of the study the body weight gain in the fungus-treated groups was 1.7 kg higher in goats and 0.7 kg higher in sheep than in the control groups (not significant). Regarding the first-year-grazing goats only, the bodyweights revealed significant differences (p<0.05). No statistically significant differences were observed in pasture larval counts.
In the study presented here, no clear effect of fungus could be observed. A modified feeding regimen, perhaps with permanent release boluses or feed blocks, may improve the efficacy. Furthermore, it seems that climatic conditions during the study period could have influenced the results and displayed how sensitive the fungus application may be on such parameters
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