72 research outputs found
Hybrid Embryo Rescue: A Non-Conventional Breeding Strategy in Horticultural Crops
Production of interspecific and intergeneric hybrids is useful for transfer of desirable genes from wild species into cultivated species. In many instances, progeny from wide crosses is difficult to produce owing to several barriers. Post-zygotic barriers such as endosperm abortion and, at later stages, embryo degeneration are of common occurrence, leading to low fertility; but these have been overcome through the use of embryo rescue and several hybrids have been developed. This approach is especially useful in horticultural crops, more so in fruit crops. In our laboratory, we have developed protocols for hybrid embryo rescue in several top-of-the-line fruit crops that suffer from an inability to cross naturally (e.g., distant crosses, use of seedless parent/s) or instances where initial fruit drop is very high. Thus, interspecific, intergeneric and intervarietal hybrids have been generated in mango, banana, seedless grape, papaya and seedless citrus using embryo rescue. Culture of embryos has also been demonstrated in rose, capsicum, hot pepper, onion and tomato. Among the very important strategies under non-GM biotechnologies figure techniques of hybrid embryo rescue, and related applications like ovule/ovary/placental cultures through sequential embryo culture. Embryo culture applied to practical problems is a tissue culture technique that has proven to be of greatest value to breeders
Benchmarking a Novel Efficient Numerical Method for Localized 1D Fermi-Hubbard Systems on a Quantum Simulator
Quantum simulators have made a remarkable progress towards exploring the
dynamics of many-body systems, many of which offer a formidable challenge to
both theoretical and numerical methods. While state-of-the-art quantum
simulators are in principle able to simulate quantum dynamics well outside the
domain of classical computers, they are noisy and limited in the variability of
the initial state of the dynamics and the observables that can be measured.
Despite these limitations, here we show that such a quantum simulator can be
used to in-effect solve for the dynamics of a many-body system. We develop an
efficient numerical technique that facilitates classical simulations in regimes
not accessible to exact calculations or other established numerical techniques.
The method is based on approximations that are well suited to describe
localized one-dimensional Fermi-Hubbard systems. Since this new method does not
have an error estimate and the approximations do not hold in general, we use a
neutral-atom Fermi-Hubbard quantum simulator with
lattice sites to benchmark its performance in terms of accuracy and convergence
for evolution times up to tunnelling times. We then use these
approximations in order to derive a simple prediction of the behaviour of
interacting Bloch oscillations for spin-imbalanced Fermi-Hubbard systems, which
we show to be in quantitative agreement with experimental results. Finally, we
demonstrate that the convergence of our method is the slowest when the
entanglement depth developed in the many-body system we consider is neither too
small nor too large. This represents a promising regime for near-term
applications of quantum simulators.Comment: 24 pages, 10 figure
Present status and future scope for fish production in cages and enclosures in India
The paper highlights the role of intensive fish husbandry system in cages and
enclosures in the overall fisheries development of the country. This system of fish culture
in widely dispersed aquatic ecosystems in India has yielded stimulating results, though there
are some immediate constraints. The pressing problems of cage size, shape and material,
diseases and parasites, and location of operational sites have been discussed. Such intensive
culture systems have numerous advantages over the traditional pond culture.
It 15 conduded that cage and enclosure culture of fifish and shellfish will ultimately
carve its niche in the streams, rivers, canals, heels, lakes, reservoirs, estuaries, lagoons, bays
and coastal areas of the country
Observing non-ergodicity due to kinetic constraints in tilted Fermi-Hubbard chains
The thermalization of isolated quantum many-body systems is deeply related to
fundamental questions of quantum information theory. While integrable or
many-body localized systems display non-ergodic behavior due to extensively
many conserved quantities, recent theoretical studies have identified a rich
variety of more exotic phenomena in between these two extreme limits. The
tilted one-dimensional Fermi-Hubbard model, which is readily accessible in
experiments with ultracold atoms, emerged as an intriguing playground to study
non-ergodic behavior in a clean disorder-free system. While non-ergodic
behavior was established theoretically in certain limiting cases, there is no
complete understanding of the complex thermalization properties of this model.
In this work, we experimentally study the relaxation of an initial
charge-density wave and find a remarkably long-lived initial-state memory over
a wide range of parameters. Our observations are well reproduced by numerical
simulations of a clean system. Using analytical calculations we further provide
a detailed microscopic understanding of this behavior, which can be attributed
to emergent kinetic constraints.Comment: accepted in Nature Communication
Mixed matrix PVDF membranes with in-situ synthesized PAMAM dendrimer- like particles: A new class of sorbents for Cu(II) recovery from aqueous solutions by ultrafiltration
A one-pot method for the preparation of a new family of mixed matrix polyvinylidene fluoride (PVDF) membranes with in-situ synthesized poly(amidoamine) [PAMAM] particles is described. The key feature of this membrane preparation method is the in-situ synthesis of PAMAM dendrimer-like particles in the dope solutions prior to membrane casting using low-generation dendrimers with terminal primary amine groups (G0 and G1-NH2) as precursors and epichlorohydrin (ECH) as cross-linker. By using a combined thermally induced phase separation (TIPS) and non-solvent induced phase separation (NIPS) casting process, a new family of asymmetric PVDF ultrafiltration membranes with (i) neutral and hydrophilic surface layers of average pore diameters of 22−45 nm, (ii) high loadings (∼48 wt %) of dendrimer-like PAMAM particles with average diameters of ∼1.3−2.4 μm, and (iii) matrices with sponge-like microstructures characteristic of membranes with strong mechanical integrity were successfully prepared. Preliminary experiments show that these new mixed matrix PVDF membranes can serve as reusable high capacity sorbents for Cu(II) recovery from aqueous solutions by ultrafiltration
Studies on Tensile Characteristics of Kevlar/Jute/ Syntactic Foam Hybrid Sandwich Composites
In this study, a structured approach combining Taguchi experimental design and analysis of variance (ANOVA) is used to investigate the effects of skin material choice, material density, and percentage of reinforcement on the tensile properties of Kelvar/jute/synthetic foam hybrid sandwich composites. By deliberately changing these variables and examining how they affect tensile strength, modulus, and other important qualities, the goal is to maximize the mechanical performance of these composites. This work gives helpful insights into the interaction of these variables and their contribution to the overall tensile behavior of the composites through a series of carefully planned experiments and statistical studies. While ANOVA aids in quantifying the importance of individual components and interactions, the Taguchi approach makes it easier to identify the ideal parameter values. Making a substantial addition to the field of materials science and engineering, this combined method provides a solid framework for improving the design and engineering of lightweight, high-strength sandwich composites with customized features
Uncomputably noisy ergodic limits
V'yugin has shown that there are a computable shift-invariant measure on
Cantor space and a simple function f such that there is no computable bound on
the rate of convergence of the ergodic averages A_n f. Here it is shown that in
fact one can construct an example with the property that there is no computable
bound on the complexity of the limit; that is, there is no computable bound on
how complex a simple function needs to be to approximate the limit to within a
given epsilon
Isotopic dependence of the giant monopole resonance in the even-A ^{112-124}Sn isotopes and the asymmetry term in nuclear incompressibility
The strength distributions of the giant monopole resonance (GMR) have been
measured in the even-A Sn isotopes (A=112--124) with inelastic scattering of
400-MeV particles in the angular range
--. We find that the experimentally-observed GMR energies
of the Sn isotopes are lower than the values predicted by theoretical
calculations that reproduce the GMR energies in Pb and Zr very
well. From the GMR data, a value of MeV is obtained
for the asymmetry-term in the nuclear incompressibility.Comment: Submitted to Physical Review Letters. 10 pages; 4 figure
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