2,097 research outputs found
Street Art as an Expression of Post-Modern Consciousness
This paper explores the development and expression of street art from the end of the twentieth century to the present day. I examine the street art’s use and definition of public space and how it challenges the prevailing paradigm on property and ownership. I explore the way that street art uses the language of advertising to reach the largest amount of people, while speaking out against all that consumerism stands for. I discuss how in braking down the boundaries between high art and low, and using images from every source imaginable, street speaks to the post-modern projects desire to see beyond disciplines and deny all hierarchies. I delve into the work of fames street artist Swoon and her art collective Toyshop and see how street art is seeking to facilitate a change in consciousness from a fixed and static way of seeing reality, to an organic and flowing mode of being
Chemical Inhibitors of the Calcium Entry Channel TRPV6
ABSTRACT: Purpose: Calcium entry channels in the plasma membrane are thought to play a major role in maintaining cellular Ca2+ levels, crucial for growth and survival of normal and cancer cells. The calcium-selective channel TRPV6 is expressed in prostate, breast, and other cancer cells. Its expression coincides with cancer progression, suggesting that it drives cancer cell growth. However, no specific inhibitors for TRPV6 have been identified thus far. Methods: To develop specific TRPV6 inhibitors, we synthesized molecules based on the lead compound TH-1177, reported to inhibit calcium entry channels in prostate cancer cells in vitro and in vivo. Results: We found that one of our compounds (#03) selectively inhibited TRPV6 over five times better than TRPV5, whereas TH-1177 and the other synthesized compounds preferentially inhibited TRPV5. The IC50 value for growth inhibition by blocking endogenous Ca2+ entry channels in the LNCaP human prostate cancer cell line was 0.44 ± 0.07μM compared to TH-1177 (50 ± 0.4μM). Conclusions: These results suggest that compound #03 is a relatively selective and potent inhibitor for TRPV6 and that it is an interesting lead compound for the treatment of prostate cancer and other cancers of epithelial origi
Heuristic-based Incremental Probabilistic Roadmap for Efficient UAV Exploration in Dynamic Environments
Autonomous exploration in dynamic environments necessitates a planner that
can proactively respond to changes and make efficient and safe decisions for
robots. Although plenty of sampling-based works have shown success in exploring
static environments, their inherent sampling randomness and limited utilization
of previous samples often result in sub-optimal exploration efficiency.
Additionally, most of these methods struggle with efficient replanning and
collision avoidance in dynamic settings. To overcome these limitations, we
propose the Heuristic-based Incremental Probabilistic Roadmap Exploration
(HIRE) planner for UAVs exploring dynamic environments. The proposed planner
adopts an incremental sampling strategy based on the probabilistic roadmap
constructed by heuristic sampling toward the unexplored region next to the free
space, defined as the heuristic frontier regions. The heuristic frontier
regions are detected by applying a lightweight vision-based method to the
different levels of the occupancy map. Moreover, our dynamic module ensures
that the planner dynamically updates roadmap information based on the
environment changes and avoids dynamic obstacles. Simulation and physical
experiments prove that our planner can efficiently and safely explore dynamic
environments
Molecular Response in One-Photon Absorption via Natural Thermal Light vs Pulsed Laser Excitation
Photoinduced biological processes occur via one photon absorption in natural
light, which is weak, CW and incoherent, but are often studied in the
laboratory using pulsed coherent light. Here we compare the response of a
molecule to these two very different sources within a quantized radiation field
picture. The latter is shown to induce coherent time evolution in the molecule,
whereas the former does not. As a result, the coherent time dependence observed
in the laboratory experiments will not be relevant to the natural biological
process. Emphasis is placed on resolving confusions regarding this issue that
are shown to arise from aspects of quantum measurement and from a lack of
appreciation of the proper description of the absorbed photon.Comment: Revised (now published) manuscript: Replaces ArXiv:1109.002
Low computational-cost detection and tracking of dynamic obstacles for mobile robots with RGB-D cameras
Deploying autonomous robots in crowded indoor environments usually requires
them to have accurate dynamic obstacle perception. Although plenty of previous
works in the autonomous driving field have investigated the 3D object detection
problem, the usage of dense point clouds from a heavy LiDAR and their high
computation cost for learning-based data processing make those methods not
applicable to small robots, such as vision-based UAVs with small onboard
computers. To address this issue, we propose a lightweight 3D dynamic obstacle
detection and tracking (DODT) method based on an RGB-D camera, which is
designed for low-power robots with limited computing power. Our method adopts a
novel ensemble detection strategy, combining multiple computationally efficient
but low-accuracy detectors to achieve real-time high-accuracy obstacle
detection. Besides, we introduce a new feature-based data association method to
prevent mismatches and use the Kalman filter with the constant acceleration
model to track detected obstacles. In addition, our system includes an optional
and auxiliary learning-based module to enhance the obstacle detection range and
dynamic obstacle identification. The users can determine whether or not to run
this module based on the available computation resources. The proposed method
is implemented in a small quadcopter, and the experiments prove that the
algorithm can make the robot detect dynamic obstacles and navigate dynamic
environments safely.Comment: 8 pages, 12 figures, 2 table
Categorization of species as native or nonnative using DNA sequence signatures without a complete reference library.
New genetic diagnostic approaches have greatly aided efforts to document global biodiversity and improve biosecurity. This is especially true for organismal groups in which species diversity has been underestimated historically due to difficulties associated with sampling, the lack of clear morphological characteristics, and/or limited availability of taxonomic expertise. Among these methods, DNA sequence barcoding (also known as "DNA barcoding") and by extension, meta-barcoding for biological communities, has emerged as one of the most frequently utilized methods for DNA-based species identifications. Unfortunately, the use of DNA barcoding is limited by the availability of complete reference libraries (i.e., a collection of DNA sequences from morphologically identified species), and by the fact that the vast majority of species do not have sequences present in reference databases. Such conditions are critical especially in tropical locations that are simultaneously biodiversity rich and suffer from a lack of exploration and DNA characterization by trained taxonomic specialists. To facilitate efforts to document biodiversity in regions lacking complete reference libraries, we developed a novel statistical approach that categorizes unidentified species as being either likely native or likely nonnative based solely on measures of nucleotide diversity. We demonstrate the utility of this approach by categorizing a large sample of specimens of terrestrial insects and spiders (collected as part of the Moorea BioCode project) using a generalized linear mixed model (GLMM). Using a training data set of known endemic (n = 45) and known introduced species (n = 102), we then estimated the likely native/nonnative status for 4,663 specimens representing an estimated 1,288 species (412 identified species), including both those specimens that were either unidentified or whose endemic/introduced status was uncertain. Using this approach, we were able to increase the number of categorized specimens by a factor of 4.4 (from 794 to 3,497), and the number of categorized species by a factor of 4.8 from (147 to 707) at a rate much greater than chance (77.6% accuracy). The study identifies phylogenetic signatures of both native and nonnative species and suggests several practical applications for this approach including monitoring biodiversity and facilitating biosecurity
Retrospective Search for Strongly Lensed Supernovae in the DESI Legacy Imaging Surveys
The introduction of deep wide-field surveys in recent years and the adoption
of machine learning techniques have led to the discoveries of
strong gravitational lensing systems and candidates.
However, the discovery of multiply lensed transients remains a rarity. Lensed
transients and especially lensed supernovae are invaluable tools to cosmology
as they allow us to constrain cosmological parameters via lens modeling and the
measurements of their time delays. In this paper, we develop a pipeline to
perform a targeted lensed transient search. We apply this pipeline to 5807
strong lenses and candidates, identified in the literature, in the DESI Legacy
Imaging Surveys Data Release 9 (DR9) footprint. For each system, we analyze
every exposure in all observed bands (DECam , , and ). Our pipeline
finds, groups, and ranks detections that are in sufficient proximity temporally
and spatially. After the first round of inspection, for promising candidate
systems, we further examine the newly available DR10 data (with additional
and bands). Here we present our targeted lensed supernova search
pipeline and seven new lensed supernova candidates, including a very likely
lensed supernova probably a Type Ia in a system with an Einstein radius
of .Comment: 53 pages, 50 figures, 3 table
A vision-based autonomous UAV inspection framework for unknown tunnel construction sites with dynamic obstacles
Tunnel construction using the drill-and-blast method requires the 3D
measurement of the excavation front to evaluate underbreak locations.
Considering the inspection and measurement task's safety, cost, and efficiency,
deploying lightweight autonomous robots, such as unmanned aerial vehicles
(UAV), becomes more necessary and popular. Most of the previous works use a
prior map for inspection viewpoint determination and do not consider dynamic
obstacles. To maximally increase the level of autonomy, this paper proposes a
vision-based UAV inspection framework for dynamic tunnel environments without
using a prior map. Our approach utilizes a hierarchical planning scheme,
decomposing the inspection problem into different levels. The high-level
decision maker first determines the task for the robot and generates the target
point. Then, the mid-level path planner finds the waypoint path and optimizes
the collision-free static trajectory. Finally, the static trajectory will be
fed into the low-level local planner to avoid dynamic obstacles and navigate to
the target point. Besides, our framework contains a novel dynamic map module
that can simultaneously track dynamic obstacles and represent static obstacles
based on an RGB-D camera. After inspection, the Structure-from-Motion (SfM)
pipeline is applied to generate the 3D shape of the target. To our best
knowledge, this is the first time autonomous inspection has been realized in
unknown and dynamic tunnel environments. Our flight experiments in a real
tunnel prove that our method can autonomously inspect the tunnel excavation
front surface.Comment: 8 pages, 8 figure
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