2,799 research outputs found
Spectral signatures of photosynthesis II: coevolution with other stars and the atmosphere on extrasolar worlds
As photosynthesis on Earth produces the primary signatures of life that can
be detected astronomically at the global scale, a strong focus of the search
for extrasolar life will be photosynthesis, particularly photosynthesis that
has evolved with a different parent star. We take planetary atmospheric
compositions simulated by Segura, et al. (2003, 2005) for Earth-like planets
around observed F2V and K2V stars, modeled M1V and M5V stars, and around the
active M4.5V star AD Leo; our scenarios use Earth's atmospheric composition as
well as very low O2 content in case anoxygenic photosynthesis dominates. We
calculate the incident spectral photon flux densities at the surface of the
planet and under water. We identify bands of available photosynthetically
relevant radiation and find that photosynthetic pigments on planets around F2V
stars may peak in absorbance in the blue, K2V in the red-orange, and M stars in
the NIR, in bands at 0.93-1.1 microns, 1.1-1.4 microns, 1.5-1.8 microns, and
1.8-2.5 microns. In addition, we calculate wavelength restrictions for
underwater organisms and depths of water at which they would be protected from
UV flares in the early life of M stars. We estimate the potential productivity
for both surface and underwater photosynthesis, for both oxygenic and
anoxygenic photosynthesis, and for hypothetical photosynthesis in which longer
wavelength, multi-photosystem series are used.Comment: 59 pages, 4 figures, 4 tables, forthcoming in Astrobiology ~March
200
GSH23.0-0.7+117, a neutral hydrogen shell in the inner Galaxy
GSH23.0-0.7+117 is a well-defined neutral hydrogen shell discovered in the
VLA Galactic Plane Survey (VGPS). Only the blueshifted side of the shell was
detected. The expansion velocity and systemic velocity were determined through
the systematic behavior of the HI emission with velocity. The center of the
shell is at (l,b,v)=(23.05,-0.77,+117 km/s). The angular radius of the shell is
6.8', or 15 pc at a distance of 7.8 kpc. The HI mass divided by the volume of
the half-shell implies an average density n_H = 11 +/- 4 cm^{-3} for the medium
in which the shell expanded. The estimated age of GSH23.0-0.7+117 is 1 Myr,
with an upper limit of 2 Myr. The modest expansion energy of 2 * 10^{48} erg
can be provided by the stellar wind of a single O4 to O8 star over the age of
the shell. The 3 sigma upper limit to the 1.4 GHz continuum flux density
(S_{1.4} < 248 mJy) is used to derive an upper limit to the Lyman continuum
luminosity generated inside the shell. This upper limit implies a maximum of
one O9 star (O8 to O9.5 taking into account the error in the distance) inside
the HI shell, unless most of the incident ionizing flux leaks through the HI
shell. To allow this, the shell should be fragmented on scales smaller than the
beam (2.3 pc). If the stellar wind bubble is not adiabatic, or the bubble has
burst (as suggested by the HI channel maps), agreement between the energy and
ionization requirements is even less likely. The limit set by the non-detection
in the continuum provides a significant challenge for the interpretation of
GSH23.0-0.7+117 as a stellar wind bubble. A similar analysis may be applicable
to other Galactic HI shells that have not been detected in the continuum.Comment: 18 pages, 6 figures. Figures 1 and 4 separately in GIF format.
Accepted for publication in Astrophysical Journa
Exploring the Design Space for Body Transformation Wearables to Support Physical Activity through Sensitizing and Bodystorming
Negative or disturbed body perceptions are often interwoven with people's physical inactivity. While wearables can support body perception changes (body transformation), the design space of body transformation wearables supporting physical activity remains narrow. To expand this design space, we conducted an embodied co-design workshop with users. Using conceptual and tangible sensitizing tools, we explored/reflected on bodily sensations at three moments of movement execution (before/during/after). Conceptual tools were used to evoke/reflect/capture past lived experiences, while tangible tools were used as ideation probes for sensory bodystorming. Two design concepts emerged, reflecting diverging approaches to body transformation wearables: one focused on reminders and movement correction; the other on sensory augmentation and facilitation. We reflect on how each facilitates useful representations of body sensations during movement, and present methodological recommendations for designing technology for sensory augmentation in this area. Finally, we propose a preliminary prototype based on our design concepts and discuss future steps
Intravenous single dose of tranexamic acid safely reduces blood loss and the need for transfusion in elderly patients with hip fracture. A randomized double-blinded controlled trial at 1-year follow-up
Background: A hip fracture usually presents significant blood loss in the perioperative period, with a transfusion rate of 20-60%. In order to reduce the complications associated with this procedure, the administration of Tranexamic Acid (TXA) has been implemented in the treatment of perioperative anemia. The objectives were to evaluate the effectiveness and safety of a single dose of intravenous Tranexamic Acid (TXA) in reducing perioperative blood loss and the requirement for transfusion in elderly patients undergoing hip fracture surgery within one postoperative year. Methods: A double-blind randomized controlled trial was conducted on 129 patients with hip fractures. After randomization, at the start of the surgery, 65 patients received a single dose of 1 gram of intravenous TXA (TXA group), and 64 received a placebo (placebo group). The primary effectiveness outcomes were the total blood loss and transfusion rate. The primary safety outcome was the rate of thromboembolic events. Data on surgical or medical infection, readmission and death were also collected. Results: The TXA group had a significant decrease in blood loss (p = 0.006) and requirement for transfusion (p < 0.001) compared with the placebo group. Likewise, there were no thromboembolic events in the TXA group and seven in the placebo group (p = 0.006). Mortality within 1-year postoperatively was not significantly different (p = 0.115). Conclusion: Using a single dose of intravenous TXA at the start of the surgery significantly reduces blood loss and the requirement for transfusion without increasing the risk of thromboembolic events or mortality within 1-year postoperatively in patients with hip fracture undergoing surgery. Registration number: NCT03211286. https://clinicaltrials.gov/ct2/show/NCT03211286. Level of evidence: I
AI-driven web API testing
Testing of web APIs is nowadays more critical than ever before,
as they are the current standard for software integration. A bug
in an organization’s web API could have a huge impact both in ternally (services relying on that API) and externally (third-party
applications and end users). Most existing tools and testing ap proaches require writing tests or instrumenting the system under
test (SUT). The main aim of this dissertation is to take web API
testing to an unprecedented level of automation and thoroughness.
To this end, we plan to apply artificial intelligence (AI) techniques
for the autonomous detection of software failures. Specifically, the
idea is to develop intelligent programs (we call them “bots”) ca pable of generating hundreds, thousands or even millions of test
inputs and to evaluate whether the test outputs are correct based
on: 1) patterns learned from previous executions of the SUT; and 2)
knowledge gained from analyzing thousands of similar programs.
Evaluation results of our initial prototype are promising, with bugs
being automatically detected in some real-world APIs.Ministerio de Economía y Competitividad BELI (TIN2015-70560-R)Ministerio de Ciencia, Innovación y Universidades RTI2018-101204-B-C21 (HORATIO)Ministerio de Educación, Cultura y Deporte FPU17/0407
Portable point-of-use photoelectrocatalytic device provides rapid water disinfection
Portable water purification devices are needed to provide safe drinking water in rural communities, developing communities with low quality centralized water distribution, and military or recreational applications. Filtration, ultraviolet light, or chemical additives provide a spectrum of alternatives to remove pathogens from water. For the first time, we design, fabricate and demonstrate the performance of a small portable photoelectric point-of-use device, and document its performance on pathogen inactivation. The device utilizes a commercial teacup from which TiO2 nanotube photoanodes were produced in-situ and, with a small rechargeable battery powered 365 nm light emitting diode, was able to achieve 5-log inactivation of Escherichia coli in 10 s and 2.6-log of Legionella in 60 s of treatment in model water samples. Treatment of natural water achieved a 1-log bacteria inactivation after 30 s due to matrix effects. The electro-photocatalytic disinfection reactor in a kup (e-DRINK) can provide a feasible and affordable solution to ensure access to clean water. More broadly, this work demonstrates the potential for illumination to improve the efficiency of electrocatalytic surfaces
Silibinin suppresses EMT-driven erlotinib resistance by reversing the high miR-21/low miR-200c signature in vivo
The flavolignan silibinin was studied for its ability to restore drug sensitivity to EGFR-mutant NSCLC xenografts with epithelial-to-mesenchymal transition (EMT)-driven resistance to erlotinib. As a single agent, silibinin significantly decreased the tumor volumes of erlotinib-refractory NSCLC xenografts by approximately 50%. Furthermore, the complete abrogation of tumor growth was observed with the co-treatment of erlotinib and silibinin. Silibinin fully reversed the EMT-related high miR-21/low miR-200c microRNA signature and repressed the mesenchymal markers SNAIL, ZEB, and N-cadherin observed in erlotinib-refractory tumors. Silibinin was sufficient to fully activate a reciprocal mesenchymal-to-epithelial transition (MET) in erlotinib-refractory cells and prevent the highly migratogenic phenotype of erlotinib-resistant NSCLC cells. Given that the various mechanisms of resistance to erlotinib result from EMT, regardless of the EGFR mutation status, a water-soluble, silibinin-rich milk thistle extract might be a suitable candidate therapy for upcoming clinical trials aimed at preventing or reversing NSCLC progression following erlotinib treatment
Extra Virgin Olive Oil Contains a Phenolic Inhibitor of the Histone Demethylase LSD1/KDM1A
The lysine-specific histone demethylase 1A (LSD1) also known as lysine (K)-specific
demethylase 1A (KDM1A) is a central epigenetic regulator of metabolic reprogramming in
obesity-associated diseases, neurological disorders, and cancer. Here, we evaluated the ability
of oleacein, a biophenol secoiridoid naturally present in extra virgin olive oil (EVOO), to target
LSD1. Molecular docking and dynamic simulation approaches revealed that oleacein could target
the binding site of the LSD1 cofactor flavin adenosine dinucleotide with high affinity and at low
concentrations. At higher concentrations, oleacein was predicted to target the interaction of LSD1
with histone H3 and the LSD1 co-repressor (RCOR1/CoREST), likely disturbing the anchorage of
LSD1 to chromatin. AlphaScreen-based in vitro assays confirmed the ability of oleacein to act as
a direct inhibitor of recombinant LSD1, with an IC50 as low as 2.5 umol/L. Further, oleacein fully
suppressed the expression of the transcription factor SOX2 (SEX determining Region Y-box 2) in cancer
stem-like and induced pluripotent stem (iPS) cells, which specifically occurs under the control of an
LSD1-targeted distal enhancer. Conversely, oleacein failed to modify ectopic SOX2 overexpression
driven by a constitutive promoter. Overall, our findings provide the first evidence that EVOO contains
a naturally occurring phenolic inhibitor of LSD1, and support the use of oleacein as a template to
design new secoiridoid-based LSD1 inhibitors.Work in the Menendez laboratory is supported by the Spanish Ministry of Science and Innovation
(Grant SAF2016-80639-P, Plan Nacional de l+D+I, founded by the European Regional Development Fund, Spain)
and by an unrestricted research grant from the Fundació Oncolliga Girona (Lliga catalana d’ajuda al malalt de
càncer, Girona). The Spanish Ministry of Economy and Competitiveness (MINECO, Project RTI2018-096724-B-C21)
and the Generalitat Valenciana (PROMETEO/2016/006) supports work in the Encinar laborator
Cognitive impairment induced by delta9-tetrahydrocannabinol occurs through heteromers between cannabinoid CB1 and serotonin 5-HT2A receptors
Delta-9-tetrahydrocannabinol (THC), the main psychoactive compound of marijuana, induces numerous undesirable effects, including memory impairments, anxiety, and dependence. Conversely, THC also has potentially therapeutic effects, including analgesia, muscle relaxation, and neuroprotection. However, the mechanisms that dissociate these responses are still not known. Using mice lacking the serotonin receptor 5-HT2A, we revealed that the analgesic and amnesic effects of THC are independent of each other: while amnesia induced by THC disappears in the mutant mice, THC can still promote analgesia in these animals. In subsequent molecular studies, we showed that in specific brain regions involved in memory formation, the receptors for THC and the 5-HT2A receptors work together by physically interacting with each other. Experimentally interfering with this interaction prevented the memory deficits induced by THC, but not its analgesic properties. Our results highlight a novel mechanism by which the beneficial analgesic properties of THC can be dissociated from its cognitive side effects
- …