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Quantifying nuclear wide chromatin compaction by phasor analysis of histone Förster resonance energy transfer (FRET) in frequency domain fluorescence lifetime imaging microscopy (FLIM) data.
The nanometer spacing between nucleosomes throughout global chromatin organisation modulates local DNA template access, and through continuous dynamic rearrangements, regulates genome function [1]. However, given that nucleosome packaging occurs on a spatial scale well below the diffraction limit, real time observation of chromatin structure in live cells by optical microscopy has proved technically difficult, despite recent advances in live cell super resolution imaging [2]. One alternative solution to quantify chromatin structure in a living cell at the level of nucleosome proximity is to measure and spatially map Förster resonance energy transfer (FRET) between fluorescently labelled histones - the core protein of a nucleosome [3]. In recent work we established that the phasor approach to fluorescence lifetime imaging microscopy (FLIM) is a robust method for the detection of histone FRET which can quantify nuclear wide chromatin compaction in the presence of cellular autofluorescence [4]. Here we share FLIM data recording histone FRET in live cells co-expressing H2B-eGFP and H2B-mCherry. The data was acquired in the frequency domain [5] and processed by the phasor approach to lifetime analysis [6]. The data can be valuable to researchers interested in using the histone FRET assay since it highlights the impact of cellular autofluorescence and acceptor-donor ratio on quantifying chromatin compaction. The data is related to the research article "Phasor histone FLIM-FRET microscopy quantifies spatiotemporal rearrangement of chromatin architecture during the DNA damage response" [4]
Mapping solar array location, size, and capacity using deep learning and overhead imagery
The effective integration of distributed solar photovoltaic (PV) arrays into
existing power grids will require access to high quality data; the location,
power capacity, and energy generation of individual solar PV installations.
Unfortunately, existing methods for obtaining this data are limited in their
spatial resolution and completeness. We propose a general framework for
accurately and cheaply mapping individual PV arrays, and their capacities, over
large geographic areas. At the core of this approach is a deep learning
algorithm called SolarMapper - which we make publicly available - that can
automatically map PV arrays in high resolution overhead imagery. We estimate
the performance of SolarMapper on a large dataset of overhead imagery across
three US cities in California. We also describe a procedure for deploying
SolarMapper to new geographic regions, so that it can be utilized by others. We
demonstrate the effectiveness of the proposed deployment procedure by using it
to map solar arrays across the entire US state of Connecticut (CT). Using these
results, we demonstrate that we achieve highly accurate estimates of total
installed PV capacity within each of CT's 168 municipal regions
Microlensing and the Stellar Mass Function
Traditional approaches to measuring the stellar mass function (MF) are
fundamentally limited because objects are detected based on their luminosity,
not their mass. These methods are thereby restricted to luminous and relatively
nearby stellar populations. Gravitational microlensing promises to
revolutionize our understanding of the MF. It is already technologically
feasible to measure the MFs of the Galactic disk and Galactic bulge as
functions of position, although the actual execution of this program requires
aggressive ground-based observations including infrared interferometry, as well
as the launching of a small satellite telescope. Rapid developments in
microlensing, including the new technique of ``pixel lensing'' of unresolved
stars, will allow one to probe the MF and luminosity function of nearby
galaxies. Such observations of M31 are already underway, and pixel-lensing
observations of M87 with the {\it Hubble Space Telescope} would permit
detection of dark intra-cluster objects in Virgo. Microlensing techniques can
also be applied to investigate the star-formation history of the universe and
to search for planets with masses as small as the Earth's. Based on an invited
talk at the January 1996 AAS meeting in San Antonio. PASP (June 1996) in press,
(c) ASP, reproduced with permission.Comment: 31 pages with 7 embedded figures. PASP (June 1996) in press, (c) ASP,
reproduced with permissio
A Neural System for Automated CCTV Surveillance
This paper overviews a new system, the “Owens
Tracker,” for automated identification of suspicious
pedestrian activity in a car-park.
Centralized CCTV systems relay multiple video streams
to a central point for monitoring by an operator. The
operator receives a continuous stream of information,
mostly related to normal activity, making it difficult to
maintain concentration at a sufficiently high level.
While it is difficult to place quantitative boundaries on
the number of scenes and time period over which
effective monitoring can be performed, Wallace and
Diffley [1] give some guidance, based on empirical and
anecdotal evidence, suggesting that the number of
cameras monitored by an operator be no greater than 16,
and that the period of effective monitoring may be as
low as 30 minutes before recuperation is required.
An intelligent video surveillance system should
therefore act as a filter, censuring inactive scenes and
scenes showing normal activity. By presenting the
operator only with unusual activity his/her attention is
effectively focussed, and the ratio of cameras to
operators can be increased.
The Owens Tracker learns to recognize environmentspecific
normal behaviour, and refers sequences of
unusual behaviour for operator attention. The system
was developed using standard low-resolution CCTV
cameras operating in the car-parks of Doxford Park
Industrial Estate (Sunderland, Tyne and Wear), and
targets unusual pedestrian behaviour.
The modus operandi of the system is to highlight
excursions from a learned model of normal behaviour in
the monitored scene. The system tracks objects and
extracts their centroids; behaviour is defined as the
trajectory traced by an object centroid; normality as the
trajectories typically encountered in the scene. The
essential stages in the system are: segmentation of
objects of interest; disambiguation and tracking of
multiple contacts, including the handling of occlusion
and noise, and successful tracking of objects that
“merge” during motion; identification of unusual
trajectories. These three stages are discussed in more
detail in the following sections, and the system
performance is then evaluated
A Star-Forming Shock Front in Radio Galaxy 4C+41.17 Resolved with Laser-Assisted Adaptive Optics Spectroscopy
Near-infrared integral-field spectroscopy of redshifted [O III], H-beta and
optical continuum emission from z=3.8 radio galaxy 4C+41.17 is presented,
obtained with the laser-guide-star adaptive optics facility on the Gemini North
telescope. Employing a specialized dithering technique, a spatial resolution of
0.10 arcsec or 0.7 kpc is achieved in each spectral element, with velocity
resolution of ~70 km/s. Spectra similar to local starbursts are found for
bright knots coincident in archival Hubble Space Telescope (HST)
restframe-ultraviolet images, which also allows a key line diagnostic to be
mapped together with new kinematic information. There emerges a clearer picture
of the nebular emission associated with the jet in 8.3 GHz and 15 GHz Very
Large Array maps, closely tied to a Ly-alpha-bright shell-shaped structure seen
with HST. This supports a previous interpretation of that arc tracing a bow
shock, inducing 10^10-11 M_solar star-formation regions that comprise the
clumpy broadband optical/ultraviolet morphology near the core.Comment: 10 pages, 6 figures, accepted for publication in A
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