A US military jet has crashed into the North Sea off the coast of Yorkshire.
A major operation is underway after the F-15 fighter jet came down near Flamborough Head in East Yorkshire, south of Scarborough. The pilot is yet to be found.
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Quantum key distribution (QKD)1,2,3 is a theoretically secure way of sharing secret keys between remote users. It has been demonstrated in a laboratory over a coiled optical fibre up to 404 kilometres long4,5,6,7. In the field, point-to-point QKD has been achieved from a satellite to a ground station up to 1,200 kilometres away8,9,10. However, real-world QKD-based cryptography targets physically separated users on the Earth, for which the maximum distance has been about 100 kilometres11,12. The use of trusted relays can extend these distances from across a typical metropolitan area13,14,15,16 to intercity17 and even intercontinental distances18. However, relays pose security risks, which can be avoided by using entanglement-based QKD, which has inherent source-independent security19,20. Long-distance entanglement distribution can be realized using quantum repeaters21, but the related technology is still immature for practical implementations22. The obvious alternative for extending the range of quantum communication without compromising its security is satellite-based QKD, but so far satellite-based entanglement distribution has not been efficient23 enough to support QKD. Here we demonstrate entanglement-based QKD between two ground stations separated by 1,120 kilometres at a finite secret-key rate of 0.12 bits per second, without the need for trusted relays. Entangled photon pairs were distributed via two bidirectional downlinks from the Micius satellite to two ground observatories in Delingha and Nanshan in China. The development of a high-efficiency telescope and follow-up optics crucially improved the link efficiency. The generated keys are secure for realistic devices, because our ground receivers were carefully designed to guarantee fair sampling and immunity to all known side channels24,25. Our method not only increases the secure distance on the ground tenfold but also increases the practical security of QKD to an unprecedented level.
To create large quantum networks, researchers will first need to develop efficient quantum repeaters. A key component of these repeaters are quantum memories, which are the quantum-mechanical equivalents of more conventional computer memories, such as random-access memories (RAM).
Ideally, a quantum memory should be able to retain information for substantial periods of time, store true quantum states, read out data efficiently and operate at low-loss telecommunication wavelengths. While research teams have made great progress in the development of quantum memories, no solution proposed so far has been able to meet all of these requirements simultaneously.
With this in mind, researchers at Delft University of Technology (TU Delft) set out to develop a new mechanical quantum memory with sufficiently long storage times, a high readout efficiency, and the ability to operate at telecom wavelengths. The memory they devised, presented in a paper published in Nature Physics, could ultimately enable the practical implementation of mechanical systems with quantum effects developed in their previous works.
For the first time, a complete time-calibrated phylogeny for a large group of invertebrates is published for an entire continent.
In a recent research paper in the open-access, peer-reviewed academic journal ZooKeys, a German-Swedish team of scientists provide a diagrammatic hypothesis of the relationships and evolutionary history for all 496 European species of butterflies currently in existence. Their study provides an important tool for evolutionary and ecological research, meant for the use of insect and ecosystem conservation.
In order to analyse the ancestral relationships and history of evolutionary divergence of all European butterflies currently inhabiting the Old continent, the team led by Martin Wiemers—affiliated with both the Senckenberg German Entomological Institute and the Helmholtz Centre for Environmental Research—UFZ, mainly used molecular data from already published sources available from NCBI GenBank, but also contributed many new sequences, some from very local endemics for which no molecular data had previously been available.
In 2005, University of California, Berkeley, researchers made the surprising discovery that making conjoined twins out of young and old mice—such that they share blood and organs—can rejuvenate tissues and reverse the signs of aging in the old mice. The finding sparked a flurry of research into whether a youngster’s blood might contain special proteins or molecules that could serve as a “fountain of youth” for mice and humans alike.
But a new study by the same team shows that similar age-reversing effects can be achieved by simply diluting the blood plasma of old mice—no young blood needed.
In the study, the team found that replacing half of the blood plasma of old mice with a mixture of saline and albumin—where the albumin simply replaces protein that was lost when the original blood plasma was removed—has the same or stronger rejuvenation effects on the brain, liver and muscle than pairing with young mice or young blood exchange. Performing the same procedure on young mice had no detrimental effects on their health.
Why does this happen?
To put things as simply as possible, the root cause of all aging is a loss of energy on the cellular level, and there are basically two major theories for why this occurs. One says cellular energy decline is the result of accumulated cellular and mitochondrial damage. In other words, it’s the result of wear and tear on a cellular level. The other theory speculates that it is the result of genetic programming, with some genes getting overexpressed while others get underexpressed as we age.
These two theories of cellular energy decline aren’t in competition with one another. They just look at the problem from two different vantage points. The reality is these “causes” are interrelated. Gene overexpression and underexpression can cause cellular damage. Cellular damage can impair gene expressions.
In July of 2015, the New Horizons spacecraft made history when it became the first robotic explorer to conduct a flyby of Pluto. This was followed by another first, when the NASA mission conducted the first flyby of a Kuiper Belt Object (KBO) on December 31st, 2018 – which has since been named Arrokoth. Now, on the edge of the Solar System, New Horizons is still yielding some groundbreaking views of the cosmos.
For example, we here on Earth are used to thinking that the positions of the stars are “fixed”. In a sense, they are, since their positions and motions are relatively uniform when seen from our perspective. But a recent experiment conducted by the New Horizons team shows how familiar stars like Proxima Centauri and Wolf 359 (two of the closest stars in our neighbors) look different when viewed from the edge of the Solar System.
Located in the constellation Leo, Wolf 359 is an M-type (red dwarf) star that is roughly 7.9 light-years from Earth. It can be found close to the same path the Sun follows through the sky (the ecliptic), but can only be seen with a telescope. And if you’re a Trekkie, you might recognize the name since it was where that major battle with the Borg took place (don’t act like you don’t know!)
A black hole, at least in our current understanding, is characterized by having “no hair,” that is, it is so simple that it can be completely described by just three parameters, its mass, its spin and its electric charge. Even though it may have formed out of a complex mix of matter and energy, all other details are lost when the black hole forms. Its powerful gravitational field creates a surrounding surface, a “horizon,” and anything that crosses that horizon (even light) cannot escape. Hence the singularity appears black, and any details about the infalling material are also lost and digested into the three knowable parameters.
Astronomers are able to measure the masses of black holes in a relatively straightforward way: watching how matter moves in their vicinity (including other black holes), affected by the gravitational field. The charges of black holes are thought to be insignificant since positive and negative infalling charges are typically comparable in number. The spins of black holes are more difficult to determine, and both rely on interpreting the X-ray emission from the hot inner edge of the accretion disk around the black hole. One method models the shape of the X-ray continuum, and it relies on good estimates of the mass, distance, and viewing angle. The other models the X-ray spectrum, including observed atomic emission lines that are often seen in reflection from the hot gas. It does not depend on knowing as many other parameters. The two methods have in general yielded comparable results.
CfA astronomer James Steiner and his colleagues reanalyzed seven sets of spectra obtained by the Rossi X-ray Timing Explorer of an outburst from a stellar-mass black hole in our galaxy called 4U1543-47. Previous attempts to estimate the spin of the object using the continuum method resulted in disagreements between papers that were considerably larger than the formal uncertainties (the papers assumed a mass of 9.4 solar-masses and a distance of 24.7 thousand light-years). Using careful refitting of the spectra and updated modeling algorithms, the scientists report a spin intermediate in size to the previous ones, moderate in magnitude, and established at a 90% confidence level. Since there have been only a few dozen well confirmed black hole spins measured to date, the new result is an important addition.
