202 research outputs found
Artificial Intelligence in Armed Forces: An Analysis
Today is the age of the Fourth Industrial Revolution. The current period of rapid, simultaneous, and systemic transformations driven by advances in science is reshaping industries, blurring geographical boundaries, challenging existing regulatory frameworks, and even redefining what it means to be human. Artificial Intelligence (AI) is the software engine that drives the Fourth Industrial Revolution. AI is creating targeted marketing, safer travel through self-driving cars, smarter weapons, and new efficiencies in manufacturing processes, supply chain management, and agricultural production. It holds the promise of solving some of the most pressing issues facing society but also presents challenges such as inscrutable “black box” algorithms, unethical use of data, and potential job displacement
Phase transitions in neutron star and magnetars and their connection with high energetic bursts in astrophysics
The phase transition from normal hadronic matter to quark matter in neutron
stars (NS) could give rise to several interesting phenomena. Compact stars can
have such exotic states up to their surface (called strange stars (SS)) or they
can have quark core surrounded by hadronic matter, known as hybrid stars (HS).
As the state of matter of the resultant SS/HS is different from the initial
hadronic matter, their masses also differ. Therefore, such conversion leads to
huge energy release, sometimes of the order of ergs. In the present
work we study the qualitative energy released by such conversion. Recent
observations reveal huge surface magnetic field in certain stars, termed
magnetars. Such huge magnetic fields can modify the equations of state (EOS) of
the matter describing the star. Therefore, the mass of magnetars are different
from normal NS. The energy released during the conversion process from neutron
magnetar (NM) to strange magnetar/hybrid magnetar (SS/HS) is different from
normal NS to SS/HS conversion. In this work we calculate the energy release
during the phase transition in magnetars. The energy released during NS to
SS/HS conversion exceeds the energy released during NM to SM/HM conversion. The
energy released during the conversion of NS to SS is always of the order of
ergs. The amount of energy released during such conversion can only
be compared to the energy observed during the gamma ray bursts (GRB). The
energy liberated during NM to HM conversion is few times lesser, and is not
likely to power GRB at cosmological distances. However, the magnetars are more
likely to lose their energy from the magnetic poles and can produce giant
flares, which are usually associated with magnetars.Comment: 14 pages, 4 figures, 4 table
Status of DDT and pyrethroid resistance in Indian aedes Albopictus and absence of knockdown resistance (kdr) mutation
Background & objectives: Aedes albopictus is one of the vectors for dengue and chikungunya and emergence of pyrethroid resistance in this species could be of a major concern in controlling the vector. This study reports insecticide susceptibility status of Ae. albopictus to DDT and pyrethroids in some Indian populations and status of presence of knockdown resistance (kdr) mutations. Methods: Three to four day old adult female Ae. albopictus collected from Delhi, Gurgaon (Haryana), Hardwar (Uttarakhand), Guwahati (Assam) and Kottayam (Kerala) were bio-assayed with DDT (4), permethrin (0.75) and deltamethrin (0.05) impregnated papers using WHO standard susceptibility test kit. Mosquitoes were PCRgenotyped for F1534C kdr-mutation in the voltage-gated sodium channel (VGSC) gene. DDT and pyrethroid resistant individuals were sequenced for partial domain II, III and IV of VGSC targeting residues S989, I1011, V1016, F1534 and D1794 where kdr mutations are reported in Ae. aegypti. Results: Adult bioassays revealed varying degree of resistance against DDT among five populations of Ae. albopictus with corrected mortalities ranging between 61 and 92. Kerala and Delhi populations showed incipient resistance against permethrin and deltamethrin respectively. All other populations were susceptible for both the synthetic pyrethroids. None of the kdr mutations was detected in any of DDT, deltamethrin and permethrin resistant individuals. Interpretation & conclusion: Ae. albopictus has developed resistance against DDT and there is emergence of incipient resistance against pyrethroids in some populations. So far, there is no evidence of presence of knockdown resistance (kdr) mutation in Ae. albopictus. © 2015, Malaria Research Center. All right reserved
Aspects of topology of condensates and knotted solitons in condensed matter systems
The knotted solitons introduced by Faddeev and Niemi is presently a subject
of great interest in particle and mathematical physics. In this paper we give a
condensed matter interpretation of the recent results of Faddeev and Niemi.Comment: v2: Added a reference to the paper E. Babaev, L.D. Faddeev and A.J.
Niemi cond-mat/0106152 where an exact equivalence was shown between the
two-condensate Ginzburg-Landau model and a version of Faddeev model.
Miscelaneous links related to knotted solitons are available at the author
homepage at http://www.teorfys.uu.se/PEOPLE/egor/ . Animations of knotted
solitons by Hietarinta and Salo are available at
http://users.utu.fi/h/hietarin/knots/c45_p2.mp
Effects of hole stress concentration and its mitigation on the tensile strength of sheet moulding compound (SMC-R50) composites
The hole stress concentration effects on the tensile strength of SMC-R50 sheet moulding compound composites were studied with consideration being given to both centric and eccentric hole locations. It is shown that the tensile strength of the R50 material is improved by applying a transverse normal pressure around the hole boundary. A few preliminary experiments indicate that the fatigue life of the R50 material can also be improved by a similar technique of applying a transverse normal pressure around an open hole.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27247/1/0000254.pd
Spin tunnelling in mesoscopic systems
We study spin tunnelling in molecular magnets as an instance of a mesoscopic
phenomenon, with special emphasis on the molecule Fe8. We show that the tunnel
splitting between various pairs of Zeeman levels in this molecule oscillates as
a function of applied magnetic field, vanishing completely at special points in
the space of magnetic fields, known as diabolical points. This phenomena is
explained in terms of two approaches, one based on spin-coherent-state path
integrals, and the other on a generalization of the phase integral (or WKB)
method to difference equations. Explicit formulas for the diabolical points are
obtained for a model Hamiltonian.Comment: 13 pages, 5 figures, uses Pramana style files; conference proceedings
articl
Constructing Exactly Solvable Pseudo-hermitian Many-particle Quantum Systems by Isospectral Deformation
A class of non-Dirac-hermitian many-particle quantum systems admitting
entirely real spectra and unitary time-evolution is presented. These quantum
models are isospectral with Dirac-hermitian systems and are exactly solvable.
The general method involves a realization of the basic canonical commutation
relations defining the quantum system in terms of operators those are hermitian
with respect to a pre-determined positive definite metric in the Hilbert space.
Appropriate combinations of these operators result in a large number of
pseudo-hermitian quantum systems admitting entirely real spectra and unitary
time evolution. Examples of a pseudo-hermitian rational Calogero model and XXZ
spin-chain are considered.Comment: To appear in the Special Issue PHHQP 2010, International Journal of
Theoretical Physics; 16 pages, LateX, no figur
Inequivalent quantization of the rational Calogero model with a Coulomb type interaction
We consider the inequivalent quantizations of a -body rational Calogero
model with a Coulomb type interaction. It is shown that for certain range of
the coupling constants, this system admits a one-parameter family of
self-adjoint extensions. We analyze both the bound and scattering state sectors
and find novel solutions of this model. We also find the ladder operators for
this system, with which the previously known solutions can be constructed.Comment: 15 pages, 3 figures, revtex4, typos corrected, to appear in EPJ
A Unified Algebraic Approach to Few and Many-Body Correlated Systems
The present article is an extended version of the paper {\it Phys. Rev.} {\bf
B 59}, R2490 (1999), where, we have established the equivalence of the
Calogero-Sutherland model to decoupled oscillators. Here, we first employ the
same approach for finding the eigenstates of a large class of Hamiltonians,
dealing with correlated systems. A number of few and many-body interacting
models are studied and the relationship between their respective Hilbert
spaces, with that of oscillators, is found. This connection is then used to
obtain the spectrum generating algebras for these systems and make an algebraic
statement about correlated systems. The procedure to generate new solvable
interacting models is outlined. We then point out the inadequacies of the
present technique and make use of a novel method for solving linear
differential equations to diagonalize the Sutherland model and establish a
precise connection between this correlated system's wave functions, with those
of the free particles on a circle. In the process, we obtain a new expression
for the Jack polynomials. In two dimensions, we analyze the Hamiltonian having
Laughlin wave function as the ground-state and point out the natural emergence
of the underlying linear symmetry in this approach.Comment: 18 pages, Revtex format, To appear in Physical Review
- …