2,961 research outputs found
Temperatures and metallicities of M giants in the galactic Bulge from low-resolution K-band spectra
With the existing and upcoming large multi-fibre low-resolution
spectrographs, the question arises how precise stellar parameters such as Teff
and [Fe/H] can be obtained from low-resolution K-band spectra with respect to
traditional photometric temperature measurements. Until now, most of the
effective temperatures in galactic Bulge studies come directly from photometric
techniques. Uncertainties in interstellar reddening and in the assumed
extinction law could lead to large systematic errors. We aim to obtain and
calibrate the relation between Teff and the first overtone bands
for M giants in the galactic Bulge covering a wide range in metallicity. We use
low-resolution spectra for 20 M giants with well-studied parameters from
photometric measurements covering the temperature range 3200 < Teff < 4500 K
and a metallicity range from 0.5 dex down to -1.2 dex and study the behaviour
of Teff and [Fe/H] on the spectral indices. We find a tight relation between
Teff and the band with a dispersion of 95 K as well as
between Teff and the with a dispersion of 120 K. We do not
find any dependence of these relations on the metallicity of the star, making
them relation attractive for galactic Bulge studies. This relation is also not
sensitive to the spectral resolution allowing to apply this relation in a more
general way.
We also found a correlation between the combination of the NaI, CaI and the
band with the metallicity of the star. However this relation is
only valid for sub-solar metallicities. We show that low-resolution spectra
provide a powerful tool to obtain effective temperatures of M giants. We show
that this relation does not depend on the metallicity of the star within the
investigated range and is also applicable to different spectral resolution.Comment: 6 pages, accepted for publication in Astronomy&Astrophysic
M Giants with IGRINS II. Chemical Evolution of Fluorine at High Metallicities
The origin and evolution of fluorine in the Milky Way galaxy is still in
debate. In particular, the increase of the [F/Fe] in metal-rich stars found
from near-IR HF-lines is challenging to explain theoretically. We determine the
fluorine abundances from 50 M giants in the solar neighbourhood spanning a
broad range of metallicities (-0.9<[Fe/H]<0.25 dex). These stars are cool
enough to have an array of HF lines in the K band. We observed the stars with
the IGRINS and investigate each of ten HF molecular lines in detail. Based on a
detailed line-by-line analysis of ten HF lines, we find that the R19, R18 and
R16 lines should primarily be used for abundance analysis. The R15, R14 and R13
lines can also be used, but the trends based on these lines show increasing
dependencies with the stellar parameters. The strongest HF lines, namely R12,
R11, R9 and R7 should be avoided since the abundances from them show
significant trends with the stellar parameters, and a high sensitivity to
variations in the microturbulence, especially for coolest metal-rich stars.
This leads to a huge scatter and high fluorine abundances for supersolar
metallicity stars, not seen in the trends from the weaker lines for the same
stars. When estimating the final mean fluorine abundance trend versus
metallicity, we neglect the fluorine abundances from the four strongest lines
(R7, R9, R11 and R12) for all stars and use only those derived from R16, R18,
and R19 for the coolest metal-rich stars. We confirm the flat trend of [F/Fe]
found in other studies in the metallicity range of -1.0<[Fe/H]<0.0. We also
find a slight enhancement at supersolar metallicities (0<[Fe/H]<0.15) but we
cannot confirm the upward trend seen at [Fe/H]>0.25. We need more observations
of M giants at super solar metallicities with a spectrometer like IGRINS to
confirm if the metal-rich fluorine abundance upturn is real or not.Comment: 11 pages, 6 figures, Accepted for publication in A&
Generation of Test Vectors for Sequential Cell Verification
For Application Specific Integrated Circuits (ASIC) and System-on-Chip (SOC) designs, Cell - Based Design (CBD) is the most prevalent practice as it guarantees a shorter design cycle, minimizes errors and is easier to maintain. In modern ASIC design, standard cell methodology is practiced with sizable libraries of cells, each containing multiple implementations of the same logic functionality, in order to give the designer differing options based on area, speed or power consumption. For such library cells, thorough verification of functionality and timing is crucial for the overall success of the chip, as even a small error can prove fatal due to the repeated use of the cell in the design. Both formal and simulation based methods are being used in the industry for cell verification. We propose a method using the latter approach that generates an optimized set of test vectors for verification of sequential cells, which are guaranteed to give complete Single Input Change transition coverage with minimal redundancy. Knowledge of the cell functionality by means of the State Table is the only prerequisite of this procedure
Innovative exploitation of deepsea crustaceans along the Kerala coast
Exploratory surveys carried out since 1965
by fishing vessels belonging to different
governmental agencies have revealed the
occurrence of commercially Important deep sea
crustaceans in trawlable concentration along
the south-west coast of India
The "karikkadi" fishery of Kerala
Parapenaeopsis stylifera, (called 'Karikkadi Chemmeen' ) is the most important species of prawn contributing to the commercial fishery of Kerala coast. An experimental shrimp trawling conducted for a period of two years has shown that during the non-monsoon period (September/October to May) most of the shrimp stocks occupy the coastal waters within the 20 m depth contour. With the commencement of southwest monsoon and the consequent changes in the environmental conditions, the prawns leave the inshore areas in large numbers to the deeper zones. The wide annual fluctuations observed at important centres, the occurrence of juvenile prawns in large quantities noticed quite often in the fishery, call for proper management and conservation measures
Observations on the prawn fishery off Sakthikulangara in the light of monsoon trawling ban
Sakthikulangara is the most important prawn landing center in Kerala. Study on the prawn fishery exploited by shrimp trawlers for a period of 15 years during 1986-200b at rnis centre indicated a decline in the landings in the first five year period followed by improved fishery between 1991 and 1995. However, decline in catch and catch rate was registered in the next 5 years. Contribution of Sakthikulangara to the Kerala prawn fishery declined from 51% in seventies to 30% in eighties and 24% in nineties. 'Karikkadi' (Parapenaeopsis stylifera) contributed
to 68% of the average annual production during 1986 - 2000. Extension of trawling to middle shelf waters and introduction of night trawling transformed the complexion of prawn fishery in the nineties with the addition of nonconventional species such as Trachypenaeus curuirostris,
Solenocera choprai and Penaeus canaliculatus. Analysis of data on prawn fishery at Sakthikulangara for a period of 20 years (1981-2000) to study the impact of ban on monsoon trawling has indicated that trawling ban for a short duration of 45 days in the first half of the season is
advantageous to the 'Karikkadi' fishery
Is the deep sea prawn fishery of Kerala sustainable?
The enterprising small and medium
shrimp trawler operators of Kerala ventured
into deep sea fishing for the first time in
November 1999 defying the longheld concept
that deep sea prawn resources could be
harvested only by means of large trawlers.
This endeavour proved successful with the
realisation of 25,647 t of deep sea prawns in
the first fishing season lasting between
November '99 and May 2000
Consultancy services in marine fisheries- A profile of technologies and experts
The ICAR system currently needs very effective
partnership between the researchers and the
user groups. The Central Marine Fisheries
Research Institute, a premier Institute under the ICAR,
has taken effective steps to introduce the services and
technologies in the marine fisheries sector, achieved
over the last 50 years R & D activities. With a viev/
to institutionalising transfer of technologies, the institute
has constituted a Consultancy Processing Cell (CPC) in
1997 for effectively serving the needs of our clients,
through the short term and long term trainings,
consultancies, contract services and contract research
Larval development of Metapenaeus moyebi (Kishinouye) reared in the laboratory
The complete larval development of Metapenaeus moyebi was studied by rearing them in the
CMFRI laboratory at Karwar. The viable eggs take 8i to 10 hours to hatch out and the duration
of nauplius stage ranges between 37 and 44 hours. The protozoea transforms into mysis after 5 to
5i days. The mysis stage lasts for 91/2 to lO1/2 days. Complete larval development from egg to postlarva
I takes 16-181 days. There are 6 nauplius sub-stages, 3 protozoea substages, 3 mysis substages
and 1 intermediate stage during the course of development. The detailed structure of the larval
substages is described and illustrated in this paper
Detailed abundance trends in the inner Galactic bulge
In this paper, we aim to derive high-precision alpha-element abundances using
CRIRES high-resolution IR spectra of 72 cool M giants of the inner Galactic
bulge. Silicon, magnesium, and calcium abundances were determined by fitting a
synthetic spectrum for each star. We also incorporated recent theoretical data
into our spectroscopic analysis (i.e. updated K-band line list, better
broadening parameter estimation, non-local thermodynamic equilibrium (NLTE)
corrections). We compare these inner bulge alpha abundance trends with those of
solar neighbourhood stars observed with IGRINS using the same line list and
analysis technique; we also compare our sample to APOGEE DR17 abundances for
inner bulge stars. We investigate bulge membership using spectro-photometric
distances and orbital simulations. We construct a chemical-evolution model that
fits our metallicity distribution function (MDF) and our alpha-element trends.
Among our 72 stars, we find four that are not bulge members. [Si/Fe] and
[Mg/Fe] versus [Fe/H] trends show a typical thick disc alpha-element behaviour,
except that we do not see any plateau at supersolar metallicities as seen in
other works. The NLTE analysis lowers [Mg/Fe] typically by 0.1 dex,
resulting in a noticeably lower trend of [Mg/Fe] versus [Fe/H]. The derived
[Ca/Fe] versus [Fe/H] trend has a larger scatter than those for Si and Mg, but
is in excellent agreement with local thin and thick disc trends. With our
updated analysis, we constructed one of the most detailed studies of the alpha
abundance trends of cool M giants in the inner Galactic bulge. We modelled
these abundances by adopting a two-infall chemical-evolution model with two
distinct gas-infall episodes with timescales of 0.4 Gyr and 2 Gyr,
respectively. Based on a very meticulous spectral analysis, we have constructed
detailed and precise chemical abundances of Mg, Si, and Ca for cool M giants.Comment: 19 pages, 11 figure
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