1,912 research outputs found
Designing fuzzy rule based classifier using self-organizing feature map for analysis of multispectral satellite images
We propose a novel scheme for designing fuzzy rule based classifier. An SOFM
based method is used for generating a set of prototypes which is used to
generate a set of fuzzy rules. Each rule represents a region in the feature
space that we call the context of the rule. The rules are tuned with respect to
their context. We justified that the reasoning scheme may be different in
different context leading to context sensitive inferencing. To realize context
sensitive inferencing we used a softmin operator with a tunable parameter. The
proposed scheme is tested on several multispectral satellite image data sets
and the performance is found to be much better than the results reported in the
literature.Comment: 23 pages, 7 figure
Beneficiation of raw materials and utilisation of fines and slags
Production of ferro-alloy on tonnage scale started in India with manganese and silicon alloys in mid-fifties This was followed by ferrochrome in late sixties. In course of time, the production capacities for these alloys have increased appreciably. A large unit for the manufac-ture of charge-chrome has been commissioned recently in 1983 and another unit under construction at present is scheduled to be commissioned in early 1985
Ultraviolet emission lines of Si II in quasars --- investigating the "Si II disaster"
The observed line intensity ratios of the Si II 1263 and 1307 \AA\ multiplets
to that of Si II 1814\,\AA\ in the broad line region of quasars are both an
order of magnitude larger than the theoretical values. This was first pointed
out by Baldwin et al. (1996), who termed it the "Si II disaster", and it has
remained unresolved. We investigate the problem in the light of newly-published
atomic data for Si II. Specifically, we perform broad line region calculations
using several different atomic datasets within the CLOUDY modeling code under
optically thick quasar cloud conditions. In addition, we test for selective
pumping by the source photons or intrinsic galactic reddening as possible
causes for the discrepancy, and also consider blending with other species.
However, we find that none of the options investigated resolves the Si II
disaster, with the potential exception of microturbulent velocity broadening
and line blending. We find that a larger microturbulent velocity () may solve the Si II disaster through continuum pumping and other
effects. The CLOUDY models indicate strong blending of the Si II 1307 \AA\
multiplet with emission lines of O I, although the predicted degree of blending
is incompatible with the observed 1263/1307 intensity ratios. Clearly, more
work is required on the quasar modelling of not just the Si II lines but also
nearby transitions (in particular those of O I) to fully investigate if
blending may be responsible for the Si II disaster.Comment: Accepted for publication in Ap
Population Genetic Structuring in Opisthorchis viverrini over Various Spatial Scales in Thailand and Lao PDR
Khon Kaen Province in northeast Thailand is known as a hot spot for opisthorchiasis in Southeast Asia. Preliminary allozyme and mitochondrial DNA haplotype data from within one endemic district in this Province (Ban Phai), indicated substantial genetic variability within Opisthorchis viverrini. Here, we used microsatellite DNA analyses to examine the genetic diversity and population structure of O. viverrini from four geographically close localities in Khon Kaen Province. Genotyping based on 12 microsatellite loci yielded a mean number of alleles per locus that ranged from 2.83 to 3.7 with an expected heterozygosity in Hardy-Weinberg equilibrium of 0.44-0.56. Assessment of population structure by pairwise F(ST) analysis showed inter-population differentiation (P<0.05) which indicates population substructuring between these localities. Unique alleles were found in three of four localities with the highest number observed per locality being three. Our results highlight the existence of genetic diversity and population substructuring in O. viverrini over a small spatial scale which is similar to that found at a larger scale. This provides the basis for the investigation of the role of parasite genetic diversity and differentiation in transmission dynamics and control of O. viverrini
Examination of the efficacies of some sampling procedures in the estimation of fish landings
The lower region of the Hooghly•Matlah estuarine system is characterized by the
presence of a number of fish landing points or centres from where the assembled fish are
transported to markets for sale and which between them receive practically the entire
. produce from this region, except for some quantity in winter which are first dried close to
the fishing grounds before being directly despatched to the marketing centres
Experimental Realization of an Exact Solution to the Vlasov Equations for an Expanding Plasma
We study the expansion of ultracold neutral plasmas in the regime in which
inelastic collisions are negligible. The plasma expands due to the thermal
pressure of the electrons, and for an initial spherically symmetric Gaussian
density profle, the expansion is self-similar. Measurements of the plasma size
and ion kinetic energy using fluorescence imaging and spectroscopy show that
the expansion follows an analytic solution of the Vlasov equations for an
adiabatically expanding plasma.Comment: 4 pages, 4 figure
Electron Temperature Evolution in Expanding Ultracold Neutral Plasmas
We have used the free expansion of ultracold neutral plasmas as a
time-resolved probe of electron temperature. A combination of experimental
measurements of the ion expansion velocity and numerical simulations
characterize the crossover from an elastic-collision regime at low initial
Gamma_e, which is dominated by adiabatic cooling of the electrons, to the
regime of high Gamma_e in which inelastic processes drastically heat the
electrons. We identify the time scales and relative contributions of various
processes, and experimentally show the importance of radiative decay and
disorder-induced electron heating for the first time in ultracold neutral
plasmas
Inositol phosphate kinases in the eukaryote landscape
Inositol phosphate encompasses a large multifaceted family of signalling molecules that originate from the combinatorial attachment of phosphate groups to the inositol ring. To date, four distinct inositol kinases have been identified, namely, IPK, ITPK, IPPK (IP5-2K), and PPIP5K. Although, ITPKs have recently been identified in archaea, eukaryotes have taken advantage of these enzymes to create a sophisticated signalling network based on inositol phosphates. However, it remains largely elusive what fundamental biochemical principles control the signalling cascade. Here, we present an evolutionary approach to understand the development of the 'inositol phosphate code' in eukaryotes. Distribution analyses of these four inositol kinase groups throughout the eukaryotic landscape reveal the loss of either ITPK, or of PPIP5K proteins in several species. Surprisingly, the loss of IPPK, an enzyme thought to catalyse the rate limiting step of IP6 (phytic acid) synthesis, was also recorded. Furthermore, this study highlights a noteworthy difference between animal (metazoan) and plant (archaeplastida) lineages. While metazoan appears to have a substantial amplification of IPK enzymes, archaeplastida genomes show a considerable increase in ITPK members. Differential evolution of IPK and ITPK between plant and animal lineage is likely reflective of converging functional adaptation of these two types of inositol kinases. Since, the IPK family comprises three sub-types IPMK, IP6K, and IP3-3K each with dedicated enzymatic specificity in metazoan, we propose that the amplified ITPK group in plant could be classified in sub-types with distinct enzymology
Using Absorption Imaging to Study Ion Dynamics in an Ultracold Neutral Plasma
We report optical absorption imaging of ultracold neutral plasmas.Images are
used to measure the ion absorption spectrum, which is Doppler-broadened.
Through the spectral width, we monitor ion equilibration in the first 250ns
after plasma formation. The equilibration leaves ions on the border between the
weakly coupled gaseous and strongly coupled liquid states. On a longer
timescale of microseconds, we observe radial acceleration of ions resulting
from pressure exerted by the trapped electron gas.Comment: 4 pages, 4 figure
Functional characterization of the Saccharomyces cerevisiae protein Chl1 reveals the role of sister chromatid cohesion in the maintenance of spindle length during S-phase arrest
BACKGROUND: Metaphase cells have short spindles for efficient bi-orientation of chromosomes. The cohesin proteins hold sister chromatids together, creating Sister Chromatid Cohesion (SCC) that helps in the maintenance of short spindle lengths in metaphase. The budding yeast protein Chl1p, which has human homologs, is required for DNA damage repair, recombination, transcriptional silencing and aging. This protein is also needed to establish SCC between sister chromatids in S-phase.
RESULTS: In the present study we have further characterized Chl1p for its role in the yeast Saccharomyces cerevisiae when cells are under replication stress. We show that when DNA replication is arrested by hydroxyurea (HU), the chl1 mutation causes growth deficiency and a mild loss in cell viability. Although both mutant and wild-type cells remained arrested with undivided nuclei, mutant cells had mitotic spindles, which were about 60-80% longer than wild-type spindles. Spindle extension occurred in S-phase in the presence of an active S-phase checkpoint pathway. Further, the chl1 mutant did not show any kinetochore-related defect that could have caused spindle extension. These cells were affected in the retention of SCC in that they had only about one-fourth of the normal levels of the cohesin subunit Scc1p at centromeres, which was sufficient to bi-orient the chromosomes. The mutant cells showed defects in SCC, both during its establishment in S-phase and in its maintenance in G2. Mutants with partial and pericentromeric cohesion defects also showed spindle elongation when arrested in S-phase by HU.
CONCLUSIONS: Our work shows that Chl1p is required for normal growth and cell viability in the presence of the replication block caused by HU. The absence of this protein does not, however, compromize the replication checkpoint pathway. Even though the chl1 mutation gives synthetic lethal interactions with kinetochore mutations, its absence does not affect kinetochore function; kinetochore-microtubule interactions remain unperturbed. Further, chl1 cells were found to lose SCC at centromeres in both S- and G2 phases, showing the requirement of Chl1p for the maintenance of cohesion in G2 phase of these cells. This work documents for the first time that SCC is an important determinant of spindle size in the yeast Saccharomyces cerevisiae when genotoxic agents cause S-phase arrest of cells
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