2,015 research outputs found
Precision stellar radial velocity measurements with FIDEOS at the ESO 1-m telescope of La Silla
We present results from the commissioning and early science programs of
FIDEOS, the new high-resolution echelle spectrograph developed at the Centre of
Astro Engineering of Pontificia Universidad Catolica de Chile, and recently
installed at the ESO 1m telescope of La Silla. The instrument provides spectral
resolution R = 43,000 in the visible spectral range 420-800 nm, reaching a
limiting magnitude of 11 in V band. Precision in the measurement of radial
velocity is guaranteed by light feeding with an octagonal optical fibre,
suitable mechanical isolation, thermal stabilisation, and simultaneous
wavelength calibration. Currently the instrument reaches radial velocity
stability of = 8 m/s over several consecutive nights of observation
Mexican Trypanosoma cruzi T. cruzi I Strains with Different Degrees of Virulence Induce Diverse Humoral and Cellular Immune Responses in a Murine Experimental Infection Model
It is has been shown that the majority of T. cruzi strains isolated from Mexico belong to the T. cruzi I (TCI). The immune response produced in response to Mexican T. cruzi I strains has not been well characterized. In this study, two Mexican T. cruzi I strains were used to infect Balb/c mice. The Queretaro (TBAR/MX/0000/Queretaro)(Qro) strain resulted in 100% mortality. In contrast, no mortality was observed in mice infected with the Ninoa (MHOM/MX/1994/Ninoa) strain. Both strains produced extended lymphocyte infiltrates in cardiac tissue. Ninoa infection induced a diverse humoral response with a higher variety of immunoglobulin isotypes than were found in Qro-infected mice. Also, a stronger inflammatory TH1 response, represented by IL-12p40, IFNγ, RANTES, MIG, MIP-1β, and MCP-1 production was observed in Qro-infected mice when compared with Ninoa-infected mice. We propose that an exacerbated TH1 immune response is a likely cause of pathological damage observed in cardiac tissue and the primary cause of death in Qro-infected mice
Elongation and fluctuations of semi-flexible polymers in a nematic solvent
We directly visualize single polymers with persistence lengths ranging from
to 16 m, dissolved in the nematic phase of rod-like {\it fd}
virus. Polymers with sufficiently large persistence length undergo a coil-rod
transition at the isotropic-nematic transition of the background solvent. We
quantitatively analyze the transverse fluctuations of semi-flexible polymers
and show that at long wavelengths they are driven by the fluctuating nematic
background. We extract both the Odijk deflection length and the elastic
constant of the background nematic phase from the data.Comment: 4 pages, 4 figures, submitted to PR
Higgs and SUSY searches at future colliders
In this talk, I discuss some aspects of Higgs searches at future colliders,
particularly comparing and contrasting the capabilities of LHC and Next Linear
Collider (NLC), including the aspects of Higgs searches in supersymmetric
theories. After this, I will discuss how the search and study of sparticles
other than the Higgs can give information about the parameters of the Minimal
Supersymmetric Standard Model (MSSM).Comment: 20 pages, 12 figures, laTeX, requires pramana.sty,ias.sty added. In
the Proceedings of XII DAE symposium, Chandigarh, December 199
The Mass-Radius Relationship for Very Low Mass Stars: Four New Discoveries from the HATSouth Survey
We report the discovery of four transiting F-M binary systems with companions
between 0.1-0.2 Msun in mass by the HATSouth survey. These systems have been
characterised via a global analysis of the HATSouth discovery data, combined
with high-resolution radial velocities and accurate transit photometry
observations. We determined the masses and radii of the component stars using a
combination of two methods: isochrone fitting of spectroscopic primary star
parameters, and equating spectroscopic primary star rotation velocity with
spin-orbit synchronisation. These new very low mass companions are HATS550-016B
(0.110 -0.006/+0.005 Msun, 0.147 -0.004/+0.003 Rsun), HATS551-019B (0.17
-0.01/+0.01 Msun, 0.18 -0.01/+0.01 Rsun), HATS551-021B (0.132 -0.005/+0.014
Msun, 0.154 -0.008/+0.006 Rsun), HATS553-001B (0.20 -0.02/+0.01 Msun, 0.22
-0.01/+0.01 Rsun). We examine our sample in the context of the radius anomaly
for fully-convective low mass stars. Combining our sample with the 13 other
well-studied very low mass stars, we find a tentative 5% systematic deviation
between the measured radii and theoretical isochrone models.Comment: 17 pages, 8 figures, accepted for publication in MNRA
HATS-9b and HATS-10b: Two Compact Hot Jupiters in Field 7 of the K2 Mission
We report the discovery of two transiting extrasolar planets by the HATSouth
survey. HATS-9b orbits an old (10.8 1.5 Gyr) V=13.3 G dwarf star, with a
period P = 1.9153 d. The host star has a mass of 1.03 M, radius of
1.503 R and effective temperature 5366 70 K. The planetary
companion has a mass of 0.837 M, and radius of 1.065 R yielding a mean
density of 0.85 g cm . HATS-10b orbits a V=13.1 G dwarf star, with a
period P = 3.3128 d. The host star has a mass of 1.1 M, radius of 1.11
R and effective temperature 5880 120 K. The planetary companion
has a mass of 0.53 M, and radius of 0.97 R yielding a mean density of
0.7 g cm . Both planets are compact in comparison with planets receiving
similar irradiation from their host stars, and lie in the nominal coordinates
of Field 7 of K2 but only HATS-9b falls on working silicon. Future
characterisation of HATS-9b with the exquisite photometric precision of the
Kepler telescope may provide measurements of its reflected light signature.Comment: 15 pages, 10 figures, accepted for publication in A
HATS-7b: A Hot Super Neptune Transiting a Quiet K Dwarf Star
IW ../submit_V2/abstract.txt ( Row 1 Col 1 6:48 Ctrl-K H for help We report
the discovery by the HATSouth network of HATS-7b, a transiting Super-Neptune
with a mass of 0.120+/-0.012MJ, a radius of 0.563+/-(0.046,0.034)RJ, and an
orbital period of 3.1853days. The host star is a moderately bright
(V=13.340+/-0.010mag, K_S=10.976+/-0.026mag) K dwarf star with a mass of
0.849+/-0.027Msun , a radius of 0.815+/-(0.049,-0.035)Rsun, and a metallicity
of [Fe/H]=+0.250+/-0.080. The star is photometrically quiet to within the
precision of the HATSouth measurements and has low RV jitter. HATS-7b is the
second smallest radius planet discovered by a wide-field ground-based transit
survey, and one of only a handful of Neptune-size planets with mass and radius
determined to 10% precision. Theoretical modeling of HATS-7b yields a
hydrogen-helium fraction of 18+/-4% (rock-iron core and H2-He envelope), or
9+/-4% (ice core and H2-He envelope), i.e.it has a composition broadly similar
to that of Uranus and Neptune, and very different from that of Saturn, which
has 75% of its mass in H2-He. Based on a sample of transiting exoplanets with
accurately (<20%) determined parameters, we establish approximate power-law
relations for the envelopes of the mass-density distribution of exoplanets.
HATS-7b, which, together with the recently discovered HATS-8b, is one of the
first two transiting super-Neptunes discovered in the Southern sky, is a prime
target for additional follow-up observations with Southern hemisphere
facilities to characterize the atmospheres of Super-Neptunes (which we define
as objects with mass greater than that of Neptune, and smaller than halfway
between that of Neptune and Saturn, i.e. 0.054 MJ<Mp<0.18 MJ).Comment: 11 pages, accepted for publication by Ap
HATS-8b: A Low-Density Transiting Super-Neptune
HATS-8b is a low density transiting super-Neptune discovered as part of the
HATSouth project. The planet orbits its solar-like G dwarf host (V=14.03
0.10 and T =5679 50 K) with a period of 3.5839 d. HATS-8b is the
third lowest mass transiting exoplanet to be discovered from a wide-field
ground based search, and with a mass of 0.138 0.019 M it is
approximately half-way between the masses of Neptune and Saturn. However
HATS-8b has a radius of 0.873 (+0.123,-0.075) R, resulting in a bulk
density of just 0.259 0.091 g.cm. The metallicity of the host star
is super-Solar ([Fe/H]=0.210 0.080), arguing against the idea that low
density exoplanets form from metal-poor environments. The low density and large
radius of HATS-8b results in an atmospheric scale height of almost 1000 km, and
in addition to this there is an excellent reference star of near equal
magnitude at just 19 arcsecond separation on the sky. These factors make
HATS-8b an exciting target for future atmospheric characterization studies,
particularly for long-slit transmission spectroscopy.Comment: 11 pages, 7 figures, accepted for publication in A
Mixing of the CP Even and the CP Odd Higgs Bosons and the EDM Constraints
The mixing among the CP even and the CP odd neutral Higgs bosons of MSSM by
one loop induced effects in the presence of CP phases is investigated using
three different mechanisms to satisfy the EDM constraints, i.e., a fine tuning
of phases, a heavy sparticle spectrum, and the cancellation mechanism. It is
shown that if a mixing effect among the CP even and the CP odd Higgs bosons is
observed experimentally, then it is only the cancellation mechanism that can
survive under the naturalness constraint.Comment: 14 pages, Latex and 4figures. A new paragraph is added and few more
references. One figure is modified. To appear in Phys. Rev.
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