5,238 research outputs found
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Cancer cell lines show high heritability for motility but not generation time
Tumour evolution depends on heritable differences between cells in traits affecting cell survival or replication. It is well established that cancer cells are genetically and phenotypically heterogeneous; however, the extent to which this phenotypic variation is heritable is far less well explored. Here, we estimate the broad-sense heritability (H2) of two cell traits related to cancer hallmarks––cell motility and generation time––within populations of four cancer cell lines in vitro and find that motility is strongly heritable. This heritability is stable across multiple cell generations, with heritability values at the high end of those measured for a range of traits in natural populations of animals or plants. These findings confirm a central assumption of cancer evolution, provide a first quantification of the evolvability of key traits in cancer cells and indicate that there is ample raw material for experimental evolution in cancer cell lines. Generation time, a trait directly affecting cell fitness, shows substantially lower values of heritability than cell speed, consistent with its having been under directional selection removing heritable variation
Probing Quintessence using BAO imprint on the cross-correlation of weak lensing and post-reionization HI 21 cm signal
In this work we investigate the possibility of constraining a thawing
Quintessence scalar field model for dark energy. We propose using the imprint
of baryon acoustic oscillation (BAO) on the cross-correlation of
post-reionization 21-cm signal and galaxy weak lensing convergence field to
tomographically measure the angular diameter distance and the Hubble
parameter . The projected errors in these quantities are then used to
constrain the Quintessence model parameters. We find that independent hrs
radio interferometric observation at four observing frequencies MHz,
MHz, MHz and MHz with a SKA-1-Mid like radio telescope in
cross-correlation with a deep weak lensing survey covering half the sky may
measure the binned and at a few percent level of sensitivity. The
Monte Carlo analysis for a power law thawing Quintessence model gives the
marginalized bounds on the initial slope ,dark energy
density parameter and the shape of the potential at
8.63%, 10.08% and 9.75% respectively. The constraints improve to 7.66%, 4.39%
and 5.86% respectively when a joint analysis with SN and other probes is
performed.Comment: 10 Pages, 7 figure
Demographics and clinical outcomes of stent restenosis following PCI from a tertiary care referral institute in South India
Expectation of forward-backward rapidity correlations in collisions at the LHC energies
Forward-backward correlation strength () as a function of pesudorapidity
intervals for experimental data from non-singly diffractive
collisions are compared to PYTHIA and PHOJET model calculations. The
correlations are discussed as a function of rapidity window ()
symmetric about the central rapidity as well as rapidity window separated by a
gap () between forward and backward regions. While the correlations
are observed to be independent of , it is found to decrease with
increase in . This reflects the role of short range correlations
and justifies the use of to obtain the accurate information about
the physics of interest, the long range correlations. The experimental
value shows a linear dependence on with the maximum value of
unity being reached at = 16 TeV, beyond the top LHC energy. However
calculations from the PYTHIA and PHOJET models indicate a deviation from linear
dependence on and saturation in the values being reached
beyond = 1.8 TeV. Such a saturation in correlation values could have
interesting physical interpretations related to clan structures in particle
production. Strong forward-backward correlations are associated with cluster
production in the collisions. The average number of charged particles to which
the clusters fragments, called the cluster size, are found to also increase
linearly with for both data and the models studied. The rate of
increase in cluster size vs. from models studied are larger
compared to those from the data and higher for PHOJET compared to PYTHIA. Our
study indicates that the forward-backward measurements will provide a clear
distinguishing observable for the models studied at LHC energies.Comment: 15 pages, 14 Figures, accepted for publication in International
Journal of Modern Physics
Post-reionization HI 21-cm signal: A probe of negative cosmological constant
In this study, we investigate a cosmological model involving a negative
cosmological constant (AdS vacua in the dark energy sector). We consider a
quintessence field on top of a negative cosmological constant and study its
impact on cosmological evolution and structure formation. We use the power
spectrum of the redshifted HI 21 cm brightness temperature maps from the
post-reionization epoch as a cosmological probe. The signature of baryon
acoustic oscillations (BAO) on the multipoles of the power spectrum is used to
extract measurements of the angular diameter distance and the Hubble
parameter . The projected errors on these are then subsequently employed
to forecast the constraints on the model parameters () using Markov Chain Monte Carlo techniques. We find that a negative
cosmological constant with a phantom dark energy equation of state (EoS) and a
higher value of is viable from BAO distance measurements data derived
from galaxy samples. We also find that BAO imprints on the 21cm power spectrum
obtained from a futuristic SKA-mid like experiment yield a error on
a negative cosmological constant and the quintessence dark energy EoS
parameters to be and
, respectively,
which is competitive with other probes reported in the literature.Comment: 14 pages, 14 figures, comments are welcom
Intensity mapping of post-reionization 21-cm signal and its cross-correlations as a probe of gravity
We propose the intensity mapping of the redshifted HI 21-cm signal from the
post-reionization epoch as a cosmological probe of gravity. We consider
the Hu-Sawicki class of gravity models characterized by a single
parameter . The modification to gravity affects the
post-reionization -cm power spectrum through the change in the growth rate
of density fluctuations. We find that a radio interferometric observation with
a SKA1-Mid like radio telescope in both auto-correlation and cross-correlation
with galaxy weak-lensing and Ly- forest may distinguish models
from cosmology at a precision which is competitive with other probes of
gravity.Comment: Accepted for publication in Journal of Astrophysics and Astronomy SKA
special issu
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Resource competition promotes tumour expansion in experimentally evolved cancer
Tumour progression involves a series of phenotypic changes to cancer cells, each of which presents therapeutic targets. Here, using techniques adapted from microbial experimental evolution, we investigate the evolution of tumour spreading - a precursor for metastasis and tissue invasion - in environments with varied resource supply. Evolutionary theory predicts that competition for resources within a population will select for individuals to move away from a natal site (i.e. disperse), facilitating the colonisation of unexploited resources and decreasing competition between kin. After approximately 100 generations in environments with low resource supply, we find that MCF7 breast cancer spheroids (small in vitro tumours) show increased spreading. Conversely, spreading slows compared to the ancestor where resource supply is high. Common garden experiments confirm that the evolutionary responses differ between selection lines; with lines evolved under low resource supply showing phenotypic plasticity in spheroid spreading rate. These differences in spreading behaviour between selection lines are heritable (stable across multiple generations), and show that the divergently evolved lines differ in their response to resource supply. We observe dispersal-like behaviour and an increased sensitivity to resource availability in our selection lines, which may be a response to selection, or alternatively may be due to epigenetic changes, provoked by prolonged resource limitation, that have persisted across many cell generations. Different clinical strategies may be needed depending on whether or not tumour progression is due to natural selection. This study highlights the effectiveness of experimental evolution approaches in cancer cell populations and demonstrates how simple model systems might enable us to observe and measure key selective drivers of clinically important traits
Reproductive biology and diet of the grey sharpnose shark Rhizoprionodon oligolinx Springer, 1964 (Chondrichthyes: Carcharhinidae) from the north-eastern Arabian Sea
Information on reproductive biology is presented for the grey sharpnose shark Rhizoprionodon oligolinx Springer, 1964 (Chondrichthyes: Carcharhiniformes), collected off the north-west coast of India in the Arabian Sea. A total of 711 individuals, of 27.0 to 93.0 cm total length (TL), 180 to 2600 g total weight (TW) were used for the study. The length-weight relationships were significantly different between the sexes. The size-at-maturity (Lm50) for females and males was estimated to be 62.3 and 59.5 cm TL respectively. Number of embryos ranged from 1 to 7 and the size at birth was estimated between 25 to 30 cm TL. Overall sex ratio favoured the females slightly at the rate of 1.27:1. There was significant positive correlation between maternal TL and number of embryos (p<0.001). Dietary analysis of stomach contents (%IRI) revealed that R. oligolinx feeds primarily on teleosts (95.5%), cephalopods (3.2%) and crustaceans (1.2%). This study presents the first detailed biological observation on size, sex composition, size-at-maturity (Lm50) and length-weight relationship of
R. oligolinx from the northern Arabian Sea
Population dynamics and stock assessment of grey sharpnose shark Rhizoprionodon oligolinx Springer, 1964 (Chondrichthyes: Carcharhinidae) from the north-west coast of India
The life history and exploitation parameters of Rhizoprionodon oligolinx Springer, 1964 were assessed using commercial landing data of 2012-2015 from Mumbai waters of India to understand the population dynamics and stock status of the species. The average annual landing of the species was estimated to be 383 t, which formed about 9.1% of the total shark landings of Maharashtra. L∞, K and t0 estimated were 97.1 cm, 0.47 yr-1 and -0.79 yr respectively. Total mortality (Z), fishing mortality (F) and natural mortality (M) rates were estimated as 2.16 yr-1, 1.48 yr-1 and 0.69 yr-1 respectively. The length at capture (L50), length at female maturity (Lm50) and male maturity (Lm50) were estimated as 49.7, 62.3 and 59.5 cm respectively, which indicated that most of the sharks entered peak phase of exploitation before attaining sexual maturity. Length-weight relationship indicated allometric growth (b>3) for the species. The species was found to be a continuous breeder and showed peak recruitment during April. The current exploitation rate (Ecur) was found to be 0.68, which is lower than Emax estimated for the species using Beverton and Holt yield per recruit analysis. Thompson and Bell prediction model showed that at current exploitation level, the biomass (B) has reduced to 32% of virgin biomass (B0) where as, the spawning stock biomass (SSB) has reduced to 16% of the virgin spawning stock biomass (SSB0). Hence the exploitation level for the species should be reduced by 40% that will ensure the availability of SSB at a relatively safer 30% level to rebuild the stock for long term sustainability of the resource
Topological Homogeneity for Electron Microscopy Images
In this paper, the concept of homogeneity is defined, from a
topological perspective, in order to analyze how uniform is the material
composition in 2D electron microscopy images. Topological multiresolution
parameters are taken into account to obtain better results than
classical techniques.Ministerio de Economía y Competitividad MTM2016-81030-PMinisterio de Economía y Competitividad TEC2012-37868-C04-0
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