172 research outputs found
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Role for polo-like kinase 4 in mediation of cytokinesis.
The mitotic protein polo-like kinase 4 (PLK4) plays a critical role in centrosome duplication for cell division. By using immunofluorescence, we confirm that PLK4 is localized to centrosomes. In addition, we find that phospho-PLK4 (pPLK4) is cleaved and distributed to kinetochores (metaphase and anaphase), spindle midzone/cleavage furrow (anaphase and telophase), and midbody (cytokinesis) during cell division in immortalized epithelial cells as well as breast, ovarian, and colorectal cancer cells. The distribution of pPLK4 midzone/cleavage furrow and midbody positions pPLK4 to play a functional role in cytokinesis. Indeed, we found that inhibition of PLK4 kinase activity with a small-molecule inhibitor, CFI-400945, prevents translocation to the spindle midzone/cleavage furrow and prevents cellular abscission, leading to the generation of cells with polyploidy, increased numbers of duplicated centrosomes, and vulnerability to anaphase or mitotic catastrophe. The regulatory role of PLK4 in cytokinesis makes it a potential target for therapeutic intervention in appropriately selected cancers
The objectness of everyday life: disburdenment or engagement?
The article grew out of a conference paper, ‘The objectness of everyday life: engagement and disburdenment’, Material Geographies, UCL, September 2002. An expanded version of the paper was included in a special themed section of an issue of Geoforum. The paper intervenes into contemporary philosophical scholarship on the nature of use-value, usability, design and ethics. The article has been directly engaged with in an academic journal; Christensen, Carleton B. (2005) ‘The Material Basis of Everyday Rationality: transformation by design or education?’, Design Philosophy Papers No.4,)
Absolute identification by relative judgment
In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative relative judgment model (RJM) in which the elemental perceptual units are representations of the differences between current and previous stimuli. These differences are used, together with the previous feedback, to respond. Without using long-term representations of absolute magnitudes, the RJM accounts for (a) information transmission limits, (b) bowed serial position effects, and (c) sequential effects, where responses are biased toward immediately preceding stimuli but away from more distant stimuli (assimilation and contrast)
Cosmology with Photometric Surveys of Type Ia Supernovae
We discuss the extent to which photometric measurements alone can be used to
identify Type Ia supernovae (SNIa) and to determine redshift and other
parameters of interest for cosmological studies. We fit the light curve data of
the type expected from a survey such as the one planned with Large Synoptic
Survey Telescope (LSST) and also to remove the contamination from the
core-collapse supernovae to SNIa samples. We generate 1000 SNIa mock flux data
for each of the LSST filters based on existing design parameters, then use a
Markov Chain Monte-Carlo (MCMC) analysis to fit for the redshift, apparent
magnitude, stretch factor and the phase of the SNIa. We find that the model
fitting works adequately well when the true SNe redshift is below 0.5, while at
the accuracy of the photometric data is almost comparable with
spectroscopic measurements of the same sample. We discuss the contamination of
Type Ib/c (SNIb/c) and Type II supernova (SNII) on the SNIa data set. We find
it is easy to distinguish the SNII through the large mismatch when
fitting to photometric data with Ia light curves. This is not the case for
SNIb/c. We implement a statistical method based on the Bayesian estimation in
order to statistically reduce the contamination from SNIb/c for cosmological
parameter measurements from the whole SNe sample. The proposed statistical
method also evaluate the fraction of the SNIa in the total SNe data set, which
provides a valuable guide to establish the degree of contamination.Comment: 9 pages, 10 figures, published in Ap
SLHAplus: a library for implementing extensions of the standard model
We provide a library to facilitate the implementation of new models in codes
such as matrix element and event generators or codes for computing dark matter
observables. The library contains a SLHA reader routine as well as
diagonalisation routines. This library is available in CalcHEP and micrOMEGAs.
The implementation of models based on this library is supported by LanHEP and
FeynRules.Comment: 18 pages, typos corrected, new paragraph in section
CalcHEP 3.4 for collider physics within and beyond the Standard Model
We present version 3.4 of the CalcHEP software package which is designed for
effective evaluation and simulation of high energy physics collider processes
at parton level.
The main features of CalcHEP are the computation of Feynman diagrams,
integration over multi-particle phase space and event simulation at parton
level. The principle attractive key-points along these lines are that it has:
a) an easy startup even for those who are not familiar with CalcHEP; b) a
friendly and convenient graphical user interface; c) the option for a user to
easily modify a model or introduce a new model by either using the graphical
interface or by using an external package with the possibility of cross
checking the results in different gauges; d) a batch interface which allows to
perform very complicated and tedious calculations connecting production and
decay modes for processes with many particles in the final state.
With this features set, CalcHEP can efficiently perform calculations with a
high level of automation from a theory in the form of a Lagrangian down to
phenomenology in the form of cross sections, parton level event simulation and
various kinematical distributions.
In this paper we report on the new features of CalcHEP 3.4 which improves the
power of our package to be an effective tool for the study of modern collider
phenomenology.Comment: 82 pages, elsarticle LaTeX, 7 Figures. Changes from v1: 1) updated
reference list and Acknowledgments; 2) 2->1 processes added to CalcHEP; 3)
particles decay (i.e. Higgs boson) into virtual W/Z decays added together
with comparison to results from Hdecay package; 4) added interface with Root
packag
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SCOPE New Photographic Practices
The photographic practices brought together for this exhibition and publication provide a broad scope of how photographic and lens based media may be used in order to have a visceral and conceptual impact. The methods on show demonstrate the way that artists might pick and choose from the approaches, processes and debates that have arisen through the medium’s history. This collection of work features film, video and photography that demand a renegotiation of the relationship between camera, subject and viewer.
Visual Art Centre Gallery, Tsinghua University, Beijing, Chin
1988: Abilene Christian College Bible Lectures - Full Text
MISSIONS IN CRISIS: CHALLENGE AND OPPORTUNITY
Being the Abilene Christian University Annual Bible Lectures 1988
Published by ACU PRESS
1634 Campus Court Abilene, Texas 7960
1989: Abilene Christian College Bible Lectures - Full Text
CHRIST AND CULTURE: The Problem of Secularism
Being the Abilene Christian University Annual Bible Lectures 1989
Published by ACU PRESS
1634 Campus Court Abilene, Texas 7960
Planetary Construction Zones in Occultation: Discovery of an Extrasolar Ring System Transiting a Young Sun-like Star and Future Prospects for Detecting Eclipses by Circumsecondary and Circumplanetary Disks
The large relative sizes of circumstellar and circumplanetary
disks imply that they might be seen in eclipse in stellar light curves. We
estimate that a survey of ~10^4 young (~10 Myr old) post-accretion pre-MS stars
monitored for ~10 years should yield at least a few deep eclipses from
circumplanetary disks and disks surrounding low mass companion stars. We
present photometric and spectroscopic data for a pre-MS K5 star (1SWASP
J140747.93-394542.6), a newly discovered ~0.9 Msun member of the ~16 Myr-old
Upper Cen-Lup subgroup of Sco-Cen at a kinematic distance of 128 pc. SuperWASP
and ASAS light curves for this star show a remarkably long, deep, and complex
eclipse event centered on 29 April 2007. At least 5 multi-day dimming events of
>0.5 mag are identified, with a >3.3 mag deep eclipse bracketed by two pairs of
~1 mag eclipses symmetrically occurring +-12 days and +-26 days before and
after. Hence, significant dimming of the star was taking place on and off over
at least a ~54 day period in 2007, and a strong >1 mag dimming event occurred
over a ~12 day span. We place a firm lower limit on the period of 850 days
(i.e. the orbital radius of the eclipser must be >1.7 AU and orbital velocity
must be <22 km/s). The shape of the light curve is similar to the lop-sided
eclipses of the Be star EE Cep. We suspect that this new star is being eclipsed
by a low-mass object orbited by a dense inner disk, girded by at least 3 dusty
rings of lower optical depth. Between these rings are at least two annuli of
near-zero optical depth (i.e. gaps), possibly cleared out by planets or moons,
depending on the nature of the secondary. For possible periods in the range
2.33-200 yr, the estimated total ring mass is ~8-0.4 Mmoon (if the rings have
optical opacity similar to Saturn's rings), and the edge of the outermost
detected ring has orbital radius ~0.4-0.09 AU.Comment: Astronomical Journal, in press, 13 figure
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