170 research outputs found
What can the SNO Neutral Current Rate teach us about the Solar Neutrino Anomaly
We investigate how the anticipated neutral current rate from will
sharpen our understanding of the solar neutrino anomaly. Quantitative analyses
are performed with representative values of this rate in the expected range of
. This would provide a signal for transition
into a state containing an active neutrino component. Assuming this state to be
purely active one can estimate both the neutrino flux and the
survival probability to a much higher precision than currently possible.
Finally the measured value of the rate will have profound implications for
the mass and mixing parameters of the solar neutrino oscillation solution.Comment: Brief discussion on the first NC result from SNO added; final version
to be published in the MPL
Evidence of a Sub-Saturn around EPIC~211945201
We report here strong evidence for a sub-Saturn around EPIC~211945201 and
confirm its planetary nature. EPIC~211945201b was found to be a planetary
candidate from {\it K2} photometry in Campaigns 5 \& 16, transiting a bright
star (, G0 spectral type) in a 19.492 day orbit. However,
the photometric data combined with false positive probability calculations
using VESPA was not sufficient to confirm the planetary scenario. Here we
present high-resolution spectroscopic follow-up of the target using the PARAS
spectrograph (19 radial velocity observations) over a time-baseline of 420
days. We conclusively rule out the possibility of an eclipsing binary system
and confirm the 2- detection of a sub-Saturn planet. The confirmed
planet has a radius of 6.12, and a mass of
~. We also place an upper limit on the mass
(within the 3- confidence interval) at 42~ above the
nominal value. This results in the Saturn-like density of
g~cm. Based on the mass and radius, we provide a
preliminary model-dependent estimate that the heavy element content is 60-70 \%
of the total mass. This detection is important as it adds to a sparse catalog
of confirmed exoplanets with masses between 10-70 and radii
between 4-8 , whose masses and radii are measured to a precision of
50\% or better (only 23 including this work).Comment: Accepted for publication in The Astronomical Journal, 17 pages, 8
figure
PARAS-2 precision radial velocimeter: optical and mechanical design of a fiber-fed high resolution spectrograph under vacuum and temperature control
We present here the optical and mechanical design of a fiber-fed High-resolution spectrograph at resolution (R) = 100,000 which will be under vacuum (0.001 to 0.005 mbar) and temperature controlled environment at 25C ± 0.001C. The spectrograph will be attached to our upcoming new PRL 2.5m aperture telescope at Gurushikar, Mount Abu, Rajasthan, India. The spectrograph is named PARAS-2 after the successful operation of PARAS (PARAS-1) with our existing 1.2m aperture telescope at Gurushikar, Mount Abu since 2012 summer. The spectrograph (PARAS-2) will be operating in the range of 380nm to 690nm wavelength in a single shot using Grism as a Cross Disperser, R4 Echelle at blaze angle of 76degrees, and pupil diameter of 200 mm. We will use a combination of octagonal and circular fibers along with double scrambler and simultaneous calibration for getting down to the RV precision of 50cm/s or better (< 50cm/s). Minimum 30% time will be reserved for exoplanet work with the spectrograph on the 2.5m telescope when it becomes operational in early 2020. The overall efficiency of the whole spectrograph (Echelle, M1, M2, FM, Grism, Camera lens system, Dewar window) excluding fiber is expected to be 22.5% - 28% and 4% - 8% including optical fiber, telescope and fibertelescope interface losses
Antimagnetic rotation and sudden change of electric quadrupole transition strength in 143Eu
Lifetimes of the states in the quadrupole structure in 143Eu have been
measured using the Doppler shift attenuation method as well as parity of the
states in the sequence has been firmly identified from polarization measurement
using the Indian National Gamma Array. The decreasing trends of the deduced
quadrupole transition strength B(E2) with spin, along with increasing J (2)
/B(E2) values before band crossing, conclusively establish the origin of these
states as arising out of antimagnetic rotation. The abrupt increase in the
B(E2) values after the band crossing in the quadrupole band, a novel feature
observed in the present experiment, may indicates the crossing of different
shears configurations resulting in re-opening of shears structure. The results
are well reproduced by numerical calculation within the framework of
semi-classical geometric model.Comment: 6 pages, 4 postscript figure
Patient-specific finite element analysis of human corneal lenticules: An experimental and numerical study.
The number of elective refractive surgeries is constantly increasing due to the drastic increase in myopia prevalence. Since corneal biomechanics are critical to human vision, accurate modeling is essential to improve surgical planning and optimize the results of laser vision correction. In this study, we present a numerical model of the anterior cornea of young patients who are candidates for laser vision correction. Model parameters were determined from uniaxial tests performed on lenticules of patients undergoing refractive surgery by means of lenticule extraction, using patient-specific models of the lenticules. The models also took into account the known orientation of collagen fibers in the tissue, which have an isotropic distribution in the corneal plane, while they are aligned along the corneal curvature and have a low dispersion outside the corneal plane. The model was able to reproduce the experimental data well with only three parameters. These parameters, determined using a realistic fiber distribution, yielded lower values than those reported in the literature. Accurate characterization and modeling of the cornea of young patients is essential to study better refractive surgery for the population undergoing these treatments, to develop in silico models that take corneal biomechanics into account when planning refractive surgery, and to provide a basis for improving visual outcomes in the rapidly growing population undergoing these treatments
Quasi 1D Nanobelts from the Sustainable Liquid Exfoliation of Terrestrial Minerals for Future Martian based Electronics
The sky is the limit with regards to the societal impact nanomaterials can
have on our lives. However, in this study we show that their potential is out
of this world. The planet Mars has an abundant source of calcium sulfate
minerals and in our work, we show that these deposits can be the basis of
transformative nanomaterials to potentially support future space endeavors.
Through a scalable eco-friendly liquid processing technique performed on two
common terrestrial gypsum, our simple method presented a cost-efficient
procedure to yield the commercially valuable intermediate phase of gypsum,
known as bassanite. Through the liquid exfoliation of bassanite powders,
suspensions of large aspect ratio anhydrite nanobelts with long-term stability
were characterized through scanning electron microscopy and Raman spectroscopy.
Transmission electron microscopy showed nanobelts to have a mesocrystal
structure, with distinct nanoparticle constituents making up the lattice.
Unexpectedly, anhydrite nanobelts had remarkable electronic properties, namely
a bandgap that was easily tuned between semiconducting (~2.2 eV) and insulating
(~4 eV) behaviors through dimensional control measured via atomic force
microscopy. To demonstrate the application potential of our nanobelts;
optoelectronic, electrochemical and nanocomposite measurements were made. For
the hydrogen evolution reaction and mechanical reinforcement, selenite-based
anhydrite nanobelts displayed superlative performances
Quasiâ1d Anhydrite nanobelts from the sustainable liquid exfoliation of terrestrial gypsum for future martian-based electronics
The sky is the limit with regards to the societal impact nanomaterials can have on the lives. However, in this study, it is shown that their potential is out of this world. The planet Mars has an abundant source of calcium sulfate minerals and in this work, it is shown that these deposits can be the basis of transformative nanomaterials to potentially support future space endeavors. Vitally, the methods applied are low cost and require no specialized instruments of great expertise, strengthening the potential involvement of nanotechnology in sustaining Martian inhabitation. Through a scalable ecoâfriendly liquid processing technique performed on two common terrestrial gypsum, this simple method presented a costâefficient procedure to yield suspensions of large aspect ratio anhydrite nanobelts with longâterm stability that are characterized through scanning electron microscopy and Raman spectroscopy. Transmission electron microscopy shows nanobelts to have a mesocrystal structure, with distinct nanoparticle constituents making up the lattice. Unexpectedly, anhydrite nanobelts have remarkable electronic properties, namely a bandgap that is easily tuned between semiconducting (â2.2Â eV) and insulating (â4Â eV) behaviors through dimensional control measured via atomic force microscopy. To demonstrate the application potential of the nanobelts; optoelectronic, electrochemical, and nanocomposite measurements are made
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