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Mar 13, 2021
When Will SpaceXâs Starman Return To Earth?
Posted by Alberto Lao in category: space travel
SpaceX sent Starman into space on a Falcon Heavy 3 years ago! But will he ever return to Earth?
Mar 13, 2021
Scientists discovered a protein responsible for aging in stem cells
Posted by Edward Futurem in categories: biotech/medical, life extension
Mar 13, 2021
Scientists unlock mysteries of worldâs oldest âcomputerâ
Posted by Muhammad Furqan in category: computing
The 2000-year-old mechanism has baffled experts since it was discovered on a shipwreck in 1901.
Mar 13, 2021
Waymo study claims robot drivers would prevent many fatal crashes
Posted by Kelvin Dafiaghor in categories: robotics/AI, transportation
Mar 13, 2021
CRISPR screen unveils new clues to the cause of uncontrolled cell division in cancer
Posted by Paul Battista in categories: bioengineering, biotech/medical, genetics
Most cancers are driven by continuous cell division, the cause of which is largely a mystery. Scientists at Vanderbilt University have discovered a genetic switch that seems to touch off that abnormal proliferation of cellsâand they did it with the gene editing system CRISPR.
Using a genomewide CRISPR screen, the Vanderbilt team discovered that deleting a protein made by the gene TRAF3 causes cells to proliferate without stopping, even after they reach a certain density that would normally signal them to stop dividing. Because TRAF3 has not been linked to cancer before, the finding could offer key insights into the development of some cancers, the researchers reported in the journal eLife.
The team started with 40 million epithelial cells, using CRISPR to select cells that kept dividing uncontrollably. They were surprised to discover that a loss of TRAF3 activates signaling that in turn drives cell proliferation. TRAF3 normally activates immunity and had not been linked to uncontrolled cell growth before, they said.
Mar 12, 2021
Stringent Limit on Primordial Magnetic Fields from the Cosmic Microwave Background Radiation
Posted by SaĂșl Morales RodriguĂ©z in category: satellites
Primordial magnetic fields (PMFs), being present before the epoch of cosmic recombination, induce small-scale baryonic density fluctuations. These inhomogeneities lead to an inhomogeneous recombination process that alters the peaks and heights of the large-scale anisotropies of the cosmic microwave background (CMB) radiation. Utilizing numerical compressible MHD calculations and a Monte Carlo Markov chain analysis, which compares calculated CMB anisotropies with those observed by the WMAP and Planck satellites, we derive limits on the magnitude of putative PMFs. We find that the total remaining present day field, integrated over all scales, cannot exceed 47 pG for scale-invariant PMFs and 8.9 pG for PMFs with a violet Batchelor spectrum at 95% confidence level.
Mar 12, 2021
Photosynthesis tunes quantum-mechanical mixing of electronic and vibrational states to steer exciton energy transfer
Posted by SaĂșl Morales RodriguĂ©z in categories: biological, evolution, quantum physics
Photosynthetic light-harvesting antennae transfer energy toward reaction centers with high efficiency, but in high light or oxidative environments, the antennae divert energy to protect the photosynthetic apparatus. For a decade, quantum effects driven by vibronic coupling, where electronic and vibrational states couple, have been suggested to explain the energy transfer efficiency, but questions remain whether quantum effects are merely consequences of molecular systems. Here, we show evidence that biology tunes interpigment vibronic coupling, indicating that the quantum mechanism is operative in the efficient transfer regime and exploited by evolution for photoprotection. Specifically, the FennaâMatthewsâOlson complex uses redox-active cysteine residues to tune the resonance between its excitons and a pigment vibration to steer excess excitation toward a quenching site.
Photosynthetic species evolved to protect their light-harvesting apparatus from photoxidative damage driven by intracellular redox conditions or environmental conditions. The FennaâMatthewsâOlson (FMO) pigmentâprotein complex from green sulfur bacteria exhibits redox-dependent quenching behavior partially due to two internal cysteine residues. Here, we show evidence that a photosynthetic complex exploits the quantum mechanics of vibronic mixing to activate an oxidative photoprotective mechanism. We use two-dimensional electronic spectroscopy (2DES) to capture energy transfer dynamics in wild-type and cysteine-deficient FMO mutant proteins under both reducing and oxidizing conditions. Under reducing conditions, we find equal energy transfer through the exciton 4â1 and 4â2â1 pathways because the exciton 4â1 energy gap is vibronically coupled with a bacteriochlorophyll-a vibrational mode.
