2,675 research outputs found
Gravitational lens candidates in the E-CDFS
We report ten lens candidates in the E-CDFS from the GEMS survey. Nine of the
systems are new detections and only one of the candidates is a known lens
system. For the most promising five systems including the known lens system, we
present results from preliminary lens mass modelling, which tests if the
candidates are plausible lens systems. Photometric redshifts of the candidate
lens galaxies are obtained from the COMBO-17 galaxy catalog. Stellar masses of
the candidate lens galaxies within the Einstein radius are obtained by using
the -band luminosity and the color-based stellar mass-to-light ratios.
As expected, the lensing masses are found to be larger than the stellar masses
of the candidate lens galaxies. These candidates have similar dark matter
fractions as compared to lenses in SLACS and COSMOS. They also roughly follow
the halo mass-stellar mass relation predicted by the subhalo abundance matching
technique. One of the candidate lens galaxies qualifies as a LIRG and may not
be a true lens because the arc-like feature in the system is likely to be an
active region of star formation in the candidate lens galaxy. Amongst the five
best candidates, one is a confirmed lens system, one is a likely lens system,
two are less likely to be lenses and the status of one of the candidates is
ambiguous. Spectroscopic follow-up of these systems is still required to
confirm lensing and/or for more accurate determination of the lens masses and
mass density profiles.Comment: 12 pages, 5 figures, 3 tables, ApJ accepte
Using simulation to estimate the power of a badger vaccine trial
The aim of this study was to estimate the power of a badger vaccine field trial using simulation techniques. The effects of sample size, sensitivity and specificity of the diagnostic test, transmission rate between unvaccinated badgers, Vaccine Efficacy for Susceptibility (VES) and Vaccine Efficacy for Infectiousness (VEI) on study power were determined. The most striking result was the large effect of the specificity of the diagnostic test on study power. Sample size had a small effect on power. Study power increased with increasing transmission rate between non-vaccinated badgers. Changes in VES had a higher impact on power than changes in VEI. In summary, study power in group randomized trials depends not only on sample size but on many other parameters. In the current vaccine trial, power was highly dependent on the specificity of the diagnostic test. Therefore, it is critical that the diagnostic test used in the badger vaccine trial is optimized to maximise test specificity
Gravitational lens modelling in a citizen science context
We develop a method to enable collaborative modelling of gravitational lenses
and lens candidates, that could be used by non-professional lens enthusiasts.
It uses an existing free-form modelling program (glass), but enables the input
to this code to be provided in a novel way, via a user-generated diagram that
is essentially a sketch of an arrival-time surface. We report on an
implementation of this method, SpaghettiLens, which has been tested in a
modelling challenge using 29 simulated lenses drawn from a larger set created
for the Space Warps citizen science strong lens search. We find that volunteers
from this online community asserted the image parities and time ordering
consistently in some lenses, but made errors in other lenses depending on the
image morphology. While errors in image parity and time ordering lead to large
errors in the mass distribution, the enclosed mass was found to be more robust:
the model-derived Einstein radii found by the volunteers were consistent with
those produced by one of the professional team, suggesting that given the
appropriate tools, gravitational lens modelling is a data analysis activity
that can be crowd-sourced to good effect. Ideas for improvement are discussed,
these include (a) overcoming the tendency of the models to be shallower than
the correct answer in test cases, leading to systematic overestimation of the
Einstein radius by 10 per cent at present, and (b) detailed modelling of arcs.Comment: 10 pages, 12 figure
Modelling and Simulation of IDMA-OFDM for Underwater Acoustic Communication
The Ocean exhibits phenomenon of changing acoustic signal transmission due to its non-stationary nature. Water columns in between transmitter and receiver are not fixed at any point of time. Thus, designing of a wireless communication systems for underwater applications becomes significantly challenging. The speed of sound in water is 1500 m/s which introduces large delay spread in acoustic signal due to multipath phenomenon. The large time delay causes Inter-symbol Interference; this ISI degrades the performance of many receivers. However orthogonal frequency division multiplexing is multi-tone modulation reduces long time delay spreads of acoustic channels. The interleave division multiple access distinguishes each user with the unique random interleaver code. The IDMA-OFDM is superior design for reducing error bursts in multi-access underwater applications. A Simulink based simulation modell of IDMA-OFDM system has been discussed in this paper. Satisfactory performance of the implementation was observed through analysis of BER with respect to SNR. The results have been concluded by comparing simulated data in BER tool of Simulink.Defence Science Journal, Vol. 65, No. 4, July 2015, pp. 307-311, DOI: http://dx.doi.org/10.14429/dsj.65.860
Knowing Values and Public Inspection
We present a basic dynamic epistemic logic of "knowing the value". Analogous
to public announcement in standard DEL, we study "public inspection", a new
dynamic operator which updates the agents' knowledge about the values of
constants. We provide a sound and strongly complete axiomatization for the
single and multi-agent case, making use of the well-known Armstrong axioms for
dependencies in databases
STUDY OF RACHANA SHARIR DESCRIBED IN LAGHUTRAYEE IN COMPARISON WITH BRIHATRAYEE
Sharir Rachana and Kriya is essential for the knowledge of Chikitsa, Shalya and Shalakya. Depending upon the availability and complete knowledge of Ashtang Ayurveda the trio of creations of Acharya Susruta, Charaka and Vagbhata is regarded as Brihatrayee. Later on the other trio of Madhava Nidan, Bhavaprakash, Sharangadhara Samhita reffered as Laghutrayee. The knowledge of Sharir and medicine available in Brihatrayee; So, Ayurvedic terminologies explaining the Sharir aspects in Samhitas are many times mentioned by comparing it with the objects commonly seen in day-to-day life. This concept of comparison may be classified on Rachnatmaka groups.
This concept helps in knowing, understanding, learning and memorizing the important features in Rachana Sharir, as a whole. Acharyas has thus greatly contributed to the Vaidyas in studying the Sharir in the language of the layman.
Sharir stands for bodily, anything related to body. It is defined by Brihatrayee Acharyas as per their ideologies. Sharirvichaya is a detailed knowledge of Sharir Anga Pratyanga which is useful for Sharir Svasthya as well as Chikitsa. All the Acharyas consider Shadangas according to their different point of view
Heavy Metals (Cd, Cu and As) Accumulation by Aquatic Plant along with Gomti River, Lucknow (U. P.)
The aquatic plants have a great importance to the removal of heavy metals from the contaminated river water. In this study the heavy metals (Cd, Cu and As) were evaluated in aquatic plants like Ranunculus sceleratus, Hydrilla virticillata, Botumusumbelatus and Sagittaria japonica collected from the 15 sites along with Gomti river, Lucknow (U. P.), Heavy metals enters into the river through the discharge of domestic sewage, industrial effluents, municipal waste water etc., The concentration of Cu was found maximum followed by Cd and least was As for all selected plants at all sites. The highest accumulation of Arsenic, Cadmium and Copper was found in Hydrilla virticillata (0.172±0.005 μg g−1 DW), Sagittaria japonica(1.62±0.02 μg g−1 DW) and Botumus umbelatus (2.08±0.07 μg g−1 DW) respectively. However, the lowest concentration of all these heavy metals was observed in Ranunculus scleratus sp. The results of this study to give the information in relation to aquatic plants growing in polluted water, which accumulates heavy metals. These findings provide are an opportunity for the removal of toxic heavy metals from the use of aquatic plants in phytoremediation and treating water bodies
- …