1,078 research outputs found
Interactive flight control system analysis program
A summary of the development, use, and documentation of the interactive software (DIGIKON IV) for flight control system analyses is presented. A list of recommendations for future development is also included
Virtual water trade and development in Africa
A debate has long existed on the relationships between human population, natural resources, and development. Recent research has expanded this debate to include the impacts of trade; specifically, virtual water trade, or the water footprint of traded commodities. We conduct an empirical analysis of the relationships between virtual water trade, population, and development in Africa. We find that increases in virtual water imports do not lead to increases in population growth nor do they diminish human welfare. We establish a new index of virtual water trade openness and show that levels of undernourishment tend to fall with increased values of virtual water trade openness. Countries with small dam storage capacity obtain a higher fraction of their agricultural water requirements from external sources, which may indicate implicit "infrastructure sharing" across nations. Globally, increased crop exports tend to correlate with increased crop water use efficiency, though this relationship does not hold for Africa. However, internal African trade is much more efficient in terms of embodied water resources than any other region in the world. Thus, internal African trade patterns may be compensating for poor internal production systems
Looking for a heavy wino LSP in collider and dark matter experiments
We investigate the phenomenology of a wino LSP as obtained in AMSB and some
string models. The WMAP constraint on the DM relic density implies a wino LSP
mass of 2.0-2.3 TeV. We find a viable signature for such a heavy wino at CLIC,
operating at its highest CM energy of 5 TeV. One also expects a viable
monochromatic -ray signal from its pair-annihilation at the galactic
centre at least for cuspy DM halo profiles.Comment: A discussion on non-perturbative effects on annihilation cross
section of TeV scale wino LSP added. Version to appear in Phys. Rev. D
A multifrequency study of the large radio galaxies 3C46 and 3C452
We present low-frequency observations starting from ~150 MHz with the Giant
Metrewave Radio Telescope (GMRT), and high-frequency observations with the Very
Large Array (VLA) of two large radio galaxies 3C46 and 3C452. These
observations were made with the objectives of estimating their spectral ages
and examining any evidence of diffuse extended emission at low radio
frequencies due to an earlier cycle of activity. While no evidence of extended
emission due to an earlier cycle of activity has been found, the spectral ages
have been estimated to be ~15 and 27 Myr for the oldest relativistic plasma
seen in the regions close to the cores for 3C46 and 3C452 respectively. The
spectra in the vicinity of the hotspots are consistent with a straight spectrum
with injection spectral indices of ~1.0 and 0.78 respectively, somewhat steeper
than theoretical expectations.Comment: Accepted for publication in MNRAS, 10 pages, 8 figures and 4 table
The Dynamics of Radio Galaxies and Double-Double Radio Galaxies
Relativistic and magnetised plasma ejected by radio loud AGNs through jets
form the diffuse lobes of radio galaxies. The radiating particles
(electron/electron-positron) in lobes emit in radio via the synchrotron process
and X-ray via inverse-Compton scattering of cosmic microwave background
photons. The thermal environment around radio galaxies emits X-rays via the
thermal bremsstrahlung process. By combining information from these processes
we can measure physical conditions in and around the radio lobes and thus study
the dynamics of radio galaxies, including double-double radio galaxies.Comment: 11 pages, 4 figures, Diffuse Radio Plasma Conference proceedings
(held in Raman Research Institute, Bangalore, India
Rejuvenated radio galaxies J0041+3224 and J1835+6204 : how long can the quiescent phase of nuclear activity last?
We present radio observations of two well-known doubledouble radio galaxies, J0041+3224 and J1835+6204, at frequencies ranging from 150 to 8460 MHz, using both the Giant Metrewave Radio Telescope and the Very Large Array. These observations, over a large radio frequency range, enable us to determine the spectra of the inner and outer lobes. Our detailed spectral ageing analysis of their inner and outer lobes demonstrates that the outer doubles of doubledouble radio galaxies are created by the previous cycle of activity, while the inner doubles are due to the present cycle of activity. The (core subtracted) spectra of the inner doubles of both sources are power laws over a large frequency range. We found that the duration of the quiescent phase of J0041+3224 is between 4 and 28 per cent of the active phase of the previous activity. The outer north-western lobe of J1835+6204 has a compact hotspot and the regions of both the outer hotspots have close to power-law (rather than curved) spectra, which indicates that the outer lobes are still fed by jet material ejected in the previous episode just before the central engine stopped powering the jet. We estimate that the duration of the quiescent phase of J1835+6204 is ?5 per cent of the duration of the active phase of the previous activity. Therefore, we conclude that the duration of the quiescent phase can be as short as a few per cent of the active phase in radio galaxies of this type.Peer reviewe
Effects of different levels of dietary nucleotide on growth performance, survival and liver enzyme activity of Caspian salmon (Salmo trutta caspius Kessler, 1877) juveniles
Caspian salmon (Salmo trutta caspius) juveniles were fed with dietary nucleotide levels of 0, 0.15, 0.25, 0.35 and 0.5% to investigate their effects on growth performance, survival rate and liver enzymes. Juveniles with an initial average weight of 12.26±0.001g were fed with the experimental diets for 60 days. The trial was carried out in 300 liter tanks each containing 35 fish which were fed with five meals a day at the rate of 34•5% of body weight. Statistical analysis was performed using One-way ANOVA. Results of the study showed that the addition of dietary nucleotide led to significant increase of body weight gain (BW), weight increase percentage (BWI), specific growth rate (SGR), protein efficiency ratio (PER), protein productive value (PPV) and feed intake but significant decrease of food conversion ratio (FCR) as compared to the control treatment (P0.05). The best value of growth improvement indices was observed at the dietary level of 0.25% nucleotide. Liver enzymes including AST, ALT and LDH at the level of 0.35% and ALP at the level of 0.25% were significantly lower than control treatment (P<0.05). Our results also indicated that dietary nucleotide can have positive effects on growth performance and would decrease liver demolition
A multifrequency study of giant radio sources I. Low-frequency Giant Metrewave Radio Telescope observations of selected sources
We present low-frequency observations with the Giant Metrewave Radio
Telescope (GMRT) of a sample of giant radio sources (GRSs), and high-frequency
observations of three of these sources with the Very Large Array (VLA). From
multifrequency observations of the lobes we estimate the magnetic field
strengths using three different approaches, and show that these differ at most
by a factor of 3. For these large radio sources the inverse-Compton
losses usually dominate over synchrotron losses when estimates of the classical
minimum energy magnetic field are used, consistent with earlier studies.
However, this is often not true if the magnetic fields are close to the values
estimated using the formalism of Beck & Krause. We also examine the spectral
indices of the cores and any evidence of recurrent activity in these sources.
We probe the environment using the symmetry parameters of these sources and
suggest that their environments are often asymmetric on scales of 1 Mpc,
consistent with earlier studies.Comment: 14 pages, 5 figures, 6 tables, one appendix; accepted for publication
in MNRA
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