611 research outputs found
Inferring land use from mobile phone activity
Understanding the spatiotemporal distribution of people within a city is
crucial to many planning applications. Obtaining data to create required
knowledge, currently involves costly survey methods. At the same time
ubiquitous mobile sensors from personal GPS devices to mobile phones are
collecting massive amounts of data on urban systems. The locations,
communications, and activities of millions of people are recorded and stored by
new information technologies. This work utilizes novel dynamic data, generated
by mobile phone users, to measure spatiotemporal changes in population. In the
process, we identify the relationship between land use and dynamic population
over the course of a typical week. A machine learning classification algorithm
is used to identify clusters of locations with similar zoned uses and mobile
phone activity patterns. It is shown that the mobile phone data is capable of
delivering useful information on actual land use that supplements zoning
regulations.Comment: To be presented at ACM UrbComp201
Light-regulated interactions with SPA proteins underlie cryptochrome-mediated gene expression.
Cryptochromes are a class of photosensory receptors that control important processes in animals and plants primarily by regulating gene expression. How photon absorption by cryptochromes leads to changes in gene expression has remained largely elusive. Three recent studies, including Lian and colleagues (pp. 1023-1028) and Liu and colleagues (pp. 1029-1034) in this issue of Genes & Development, demonstrate that the interaction of light-activated Arabidopsis cryptochromes with a class of regulatory components of E3 ubiquitin ligase complexes leads to environmentally controlled abundance of transcriptional regulators
Can conventional forces really explain the anomalous acceleration of Pioneer 10/11 ?
A conventional explanation of the correlation between the Pioneer 10/11
anomalous acceleration and spin-rate change is given. First, the rotational
Doppler shift analysis is improved. Finally, a relation between the radio beam
reaction force and the spin-rate change is established. Computations are found
in good agreement with observational data. The relevance of our result to the
main Pioneer 10/11 anomalous acceleration is emphasized. Our analysis leads us
to conclude that the latter may not be merely artificial.Comment: 9 pages, no figur
UVR8-mediated inhibition of shade avoidance involves HFR1 stabilization in Arabidopsis.
Sun-loving plants perceive the proximity of potential light-competing neighboring plants as a reduction in the red:far-red ratio (R:FR), which elicits a suite of responses called the "shade avoidance syndrome" (SAS). Changes in R:FR are primarily perceived by phytochrome B (phyB), whereas UV-B perceived by UV RESISTANCE LOCUS 8 (UVR8) elicits opposing responses to provide a counterbalance to SAS, including reduced shade-induced hypocotyl and petiole elongation. Here we show at the genome-wide level that UVR8 broadly suppresses shade-induced gene expression. A subset of this gene regulation is dependent on the UVR8-stabilized atypical bHLH transcription regulator LONG HYPOCOTYL IN FAR-RED 1 (HFR1), which functions in part redundantly with PHYTOCHROME INTERACTING FACTOR 3-LIKE 1 (PIL1). In parallel, UVR8 signaling decreases protein levels of the key positive regulators of SAS, namely the bHLH transcription factors PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PIF5, in a COP1-dependent but HFR1-independent manner. We propose that UV-B antagonizes SAS via two mechanisms: degradation of PIF4 and PIF5, and HFR1- and PIL1-mediated inhibition of PIF4 and PIF5 function. This work highlights the importance of typical and atypical bHLH transcription regulators for the integration of light signals from different photoreceptors and provides further mechanistic insight into the crosstalk of UVR8 signaling and SAS
A comparative study of deconvolution techniques for quantum-gas microscope images
Quantum-gas microscopes are used to study ultracold atoms in optical lattices
at the single particle level. In these system atoms are localised on lattice
sites with separations close to or below the diffraction limit. To determine
the lattice occupation with high fidelity, a deconvolution of the images is
often required. We compare three different techniques, a local iterative
deconvolution algorithm, Wiener deconvolution and the Lucy-Richardson
algorithm, using simulated microscope images. We investigate how the
reconstruction fidelity scales with varying signal-to-noise ratio, lattice
filling fraction, varying fluorescence levels per atom, and imaging resolution.
The results of this study identify the limits of singe-atom detection and
provide quantitative fidelities which are applicable for different atomic
species and quantum-gas microscope setups
From a Lose–Lose to a Win–Win Situation: User-Friendly Biomass Models for Acacia longifolia to Aid Research, Management and Valorisation
Woody invasive species pose a big threat to ecosystems worldwide. Among them, Acacia
longifolia is especially aggressive, fundamentally changing ecosystem structure through massive
biomass input. This biomass is rarely harvested for usage; thus, these plants constitute a nuisance
for stakeholders who invest time and money for control without monetary return. Simultaneously,
there is an increased effort to valorise its biomass, e.g., for compost, growth substrate or as biofuel.
However, to incentivise A. longifolia harvest and usage, stakeholders need to be able to estimate
what can be obtained from management actions. Thus, the total biomass and its quality (C/N ratio)
need to be predicted to perform cost–benefit analyses for usage and determine the level of invasion
that has already occurred. Here, we report allometric biomass models for major biomass pools, as
well as give an overview of biomass quality. Subsequently, we derive a simplified volume-based
model (BM ~ 6.297 + 0.982 × Vol; BM = total dry biomass and Vol = plant volume), which can be
applied to remote sensing data or with in situ manual measurements. This toolkit will help local
stakeholders, forest managers or municipalities to predict the impact and valorisation potential of
this invasive species and could ultimately encourage its management.info:eu-repo/semantics/publishedVersio
Topological Origin of Fracture Toughening in Complex Solids: the Viewpoint of Rigidity Theory
In order to design tougher materials, it is crucial to understand the
relationship between their composition and their resistance to fracture. To
this end, we investigate the fracture toughness of usual sodium silicate
glasses (NS) and complex calcium--silicate--hydrates (CSH), the binding phase
of cement. Their atomistic structure is described in the framework of the
topological constraints theory, or rigidity theory. We report an analogous
rigidity transition, driven by pressure in NS and by composition in CSH.
Relying both on simulated and available experimental results, we show that
optimally constrained isostatic systems show improved fracture toughness. The
flexible to stressed--rigid transition is shown to be correlated to a
ductile-to-brittle transition, with a local minimum of the brittleness for
isostatic system. This fracture toughening arises from a reversible molecular
network, allowing optimal stress relaxation and crack blunting behaviors. This
opens the way to the discovery of high-performance materials, designed at the
molecular scale
Exploring Change in Neanderthal Behavioural Complexity: An Innovative Approach to the Study of Neanderthal Behaviour
Diachronic approaches provide potential for a more sophisticated framework within which to examine change in Neanderthal behavioural complexity using archaeological proxies such as symbolic artefacts, faunal assemblages and technology. Analysis of the temporal appearance and distribution of such artefacts and assemblages provide the basis for identifying changes in Neanderthal behavioural complexity in terms of symbolism, faunal extraction and technology respectively. Although changes in technology and faunal extraction were examined in the wider study, only the results of the symbolic study are presented below to illustrate the potential of the approach
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