12,496 research outputs found
Paradigms for Parameterized Enumeration
The aim of the paper is to examine the computational complexity and
algorithmics of enumeration, the task to output all solutions of a given
problem, from the point of view of parameterized complexity. First we define
formally different notions of efficient enumeration in the context of
parameterized complexity. Second we show how different algorithmic paradigms
can be used in order to get parameter-efficient enumeration algorithms in a
number of examples. These paradigms use well-known principles from the design
of parameterized decision as well as enumeration techniques, like for instance
kernelization and self-reducibility. The concept of kernelization, in
particular, leads to a characterization of fixed-parameter tractable
enumeration problems.Comment: Accepted for MFCS 2013; long version of the pape
Fixed-parameter tractability of multicut parameterized by the size of the cutset
Given an undirected graph , a collection of
pairs of vertices, and an integer , the Edge Multicut problem ask if there
is a set of at most edges such that the removal of disconnects
every from the corresponding . Vertex Multicut is the analogous
problem where is a set of at most vertices. Our main result is that
both problems can be solved in time , i.e.,
fixed-parameter tractable parameterized by the size of the cutset in the
solution. By contrast, it is unlikely that an algorithm with running time of
the form exists for the directed version of the problem, as
we show it to be W[1]-hard parameterized by the size of the cutset
Comparison of effectiveness of heat and cold shocks applied in the induction of gynogenesis in Clarias gariepinus (Burchell)
An experiment was conducted to optimize the procedure of gynogenesis in African catfish, Clarias gariepinus by suppressing meiotic and mitotic cell divisions in fertilized eggs. Gynogensis was conducted by fertilizing normal eggs with UV-irradiated sperm followed by either heat or cold shocking Irradiation of spermatozoa was given for a duration of 1 min and the eggs were fertilized in vitro. Cold shock at a temperature of
3± 1°C for a duration of 30 and 60 min and heat shock at a temperature of 39± 1°C for a duration of 1 and 2 min was applied to induce diploidy. Higher percentage of hatching (68.66) was observed for meiotic gynogens at a shock temperature of 39± 1°C for a duration of 1 min, 5 min after fertilization (af). Higher percentage of mitotic gynogenetic induction (15.33) was observed at a temperature shock of 39± 1°C for a duration of 1 min, 30 min af
Time-reversible Born-Oppenheimer molecular dynamics
We present a time-reversible Born-Oppenheimer molecular dynamics scheme,
based on self-consistent Hartree-Fock or density functional theory, where both
the nuclear and the electronic degrees of freedom are propagated in time. We
show how a time-reversible adiabatic propagation of the electronic degrees of
freedom is possible despite the non-linearity and incompleteness of the
self-consistent field procedure. Time-reversal symmetry excludes a systematic
long-term energy drift for a microcanonical ensemble and the number of
self-consistency cycles can be kept low (often only 2-4 cycles per nuclear time
step) thanks to a good initial guess given by the adiabatic propagation of the
electronic degrees of freedom. The time-reversible Born-Oppenheimer molecular
dynamics scheme therefore combines a low computational cost with a physically
correct time-reversible representation of the dynamics, which preserves a
detailed balance between propagation forwards and backwards in time.Comment: 4 pages, 4 figure
Wavefunction extended Lagrangian Born-Oppenheimer molecular dynamics
Extended Lagrangian Born-Oppenheimer molecular dynamics [Niklasson, Phys.
Rev. Lett. 100 123004 (2008)] has been generalized to the propagation of the
electronic wavefunctions. The technique allows highly efficient first
principles molecular dynamics simulations using plane wave pseudopotential
electronic structure methods that are stable and energy conserving also under
incomplete and approximate self-consistency convergence. An implementation of
the method within the planewave basis set is presented and the accuracy and
efficiency is demonstrated both for semi-conductor and metallic materials.Comment: 6 pages, 3 figure
Hybridization between Indian catfish, ♀Heteropneustes fossilis (Bloch) and Asian catfish, Clarias batrachus ♂ (Linn.)
Success has been achieved in intergeneric hybridization between two air breathing catfishes by crossing Indian catfish, Heteropneustes fossilis (Bloch) and Asian catfish, Clarias batrachus (Linn.) by in vitro fertilization technique. Four experimental trials were attempted and the highest fertilization (55.44%) and hatching (50.49%) rates were observed in the experiment IV. After 90 days of rearing, the growth rate of hybrids (65.3 ± 0.78 mm) was found to be higher than H. fossilis (55.2 ± 3.76 mm) and less than the C. batrachus (75.7 ± 0.9 mm). The survival rate of hybrids (24.75%) was observed to be less than H. fossilis (75.70%) and C. batrachus (73.13%). The karyological examination revealed that the hybrids possessed intermediate chromosomes (2n=53) between H. fossilis (2n=56) and C. batrachus (2n=50). Morphologically, the hybrids resembled one of the parent’s C. batrachus and the dorsal fin was found almost in confluent with the tail fin.Keywords: Heteropneustes fossilis, Clarias batrachus, intergeneric hybridization, chromosomes, in vitro fertilizationAfrican Journal of Biotechnology Vol. 12(9), pp. 976-98
Chromosomal locations of twelve isozyme loci in Pisum sativum
Approximate chromosomal locations of 12 loci specifying electrophoretic enzyme variants are described in the garden pea (Pisum sativum L.). The enzyme loci are distributed on five of the seven chromosomes. The position of the loci on chromosomes 2 and 3 are such that most of the known markers on these chromosomes will exhibit linkage with at least one of the isozyme loci. Several of the loci studied code for enzymes that have isozymic counterparts in other compartments of the cell. In order to distinguish among the genes coding these isozymes we have added a suffix to the locus designation corresponding to the intracellular location of its produc
Dmitri Shalin Interview with Gary T. Marx about Erving Goffman entitled Marx-Shalin Exchange on the Goffman Project
The following email exchange between Dmitri Shalin and Gary T. Marx, Professor Emeritus of sociology, Massachusetts Institute of Technology, took place between August 27, 2008, and October 16, 2008. The exchange was occasioned by Shalin’s paper “Goffman’s Biography and Interaction Order: A Study in Biocritical Hermeneutics.” The original text is in black, Marx’s comments are marked red, and Shalin’s response is in blue
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