A team of researchers affiliated with multiple institutions in the U.K. has discovered how cells are able to travel so accurately through the human body. In their paper published in the journal Science, the group describes a theory they developed to explain cell orienteering and how they tested it using mazes.

When the body is injured, such as being poked with a needle, the immune system responds by sending white blood cells to kill any bacteria that might be trying to enter through the wound. But how do the cells know how to find the wound? Prior research has shown that cells use chemicals in the body known as chemoattractants to navigate short distances. White blood cells can sense and move toward them — but it only works for short distances. In this new effort, the researchers found that cells can use such chemoattractants in a different way to navigate longer and more complicated pathways.

The researchers theorized that certain cells navigate by breaking down chemoattractants that are close to them. They then sense the degree to which the chemoattractants are replenished, and most importantly, in which direction. By noting the position of the new chemoattractants, they are able to move toward their desired destination. As an example, a white blood cell working its way to a wound upon finding a fork in the road would choose the path with the most or newest chemoattractants after it breaks them down in both directions.

To test their theory, the researchers first created computer models to test its soundness. Doing so convinced them they were on the right track. Next, they etched a host of tiny mazes onto silicon chips, added chemoattractants and then dropped in soil amoebae that are known to navigate. They then watched as the amoebae broke down the chemoattractants they found in their path and then continued on their way in the direction in which new chemoattractants were filling in for the old. They found that the amoebae were very good at finding their way to destinations on relatively simple mazes, but were less skilled in those that were more complicated and had long dead ends. Still, nearly half of those tested managed to find their way through. The researchers suggest the accuracy declines as more time is taken to parse a maze. Those cells at the tail end of a group find all the chemoattractants have already been broken down by those ahead of them, and thus have nothing to use as a guide.

If a tree falls in a forest and no one is there to hear it, does it make a sound? Perhaps not, some say.

And if someone is there to hear it? If you think that means it obviously did make a sound, you might need to revise that opinion.

We have found a new paradox in quantum mechanics - one of our two most fundamental scientific theories, together with Einstein's theory of relativity - that throws doubt on some common-sense ideas about physical reality.

Quantum mechanics vs common sense

Take a look at these three statements:

1. When someone observes an event happening, it really happened.
2. It is possible to make free choices, or at least, statistically random choices.
3. A choice made in one place can't instantly affect a distant event. (Physicists call this "locality".)

These are all intuitive ideas, and widely believed even by physicists. But our research, published in Nature Physics, shows they cannot all be true - or quantum mechanics itself must break down at some level.

This is the strongest result yet in a long series of discoveries in quantum mechanics that have upended our ideas about reality. To understand why it's so important, let's look at this history.

Your life's memories could, in principle, be stored in the universe's structure.

Christof Koch, a leading researcher on consciousness and the human brain, has famously called the brain "the most complex object in the known universe." It's not hard to see why this might be true. With a hundred billion neurons and a hundred trillion connections, the brain is a dizzyingly complex object.

But there are plenty of other complicated objects in the universe. For example, galaxies can group into enormous structures (called clusters, superclusters, and filaments) that stretch for hundreds of millions of light-years. The boundary between these structures and neighboring stretches of empty space called cosmic voids can be extremely complex.1 Gravity accelerates matter at these boundaries to speeds of thousands of kilometers per second, creating shock waves and turbulence in intergalactic gases. We have predicted that the void-filament boundary is one of the most complex volumes of the universe, as measured by the number of bits of information it takes to describe it.

This got us to thinking: Is it more complex than the brain?

Reduced resilience of plant biomes in North America could be setting the stage for the kind of mass extinctions not seen since the retreat of glaciers and arrival of humans about 13,000 years ago, cautions a new study published August 20 in the journal Global Change Biology.

The warning comes from a study of 14,189 fossil pollen samples taken from 358 locations across the continent. Researchers at the Georgia Institute of Technology used data from the samples to determine landscape resilience, including how long specific landscapes such as forests and grasslands existed — a factor known as residence time — and how well they rebounded following perturbations such as forest fires — a factor termed recovery.

Authors Yue Wang, Benjamin Shipley, Daniel Lauer, Roseann Pineau and Jenny McGuire wrote:

"Our work indicates that landscapes today are once again exhibiting low resilience, foreboding potential extinctions to come. Conservation strategies focused on improving both landscape and ecosystem resilience by increasing local connectivity and targeting regions with high richness and diverse landforms can mitigate these extinction risks."

The research, supported by the National Science Foundation, is believed to be the first to quantify biome residence and recovery time over an extended period of time. The researchers studied 12 major plant biomes in North America over the past 20,000 years using pollen data from the Neotoma Paleoecology Database.

A cosmic dance between two merging galaxies, each one containing a supermassive black hole that's rapidly feeding on so much material it creates a phenomenon known as a quasar, is a rare find.

Astronomers have discovered several pairs of such merging galaxies, or luminous "dual" quasars, using three Maunakea Observatories in Hawaii — Subaru Telescope, W. M. Keck Observatory, and Gemini Observatory. These dual quasars are so rare, a research team led by the Kavli Institute for the Physics and Mathematics of the Universe at the University of Tokyo estimates only 0.3% of all known quasars have two supermassive black holes that are on a collision course with each other.

The study published today in the August 26, 2020 issue of The Astrophysical Journal.

"In spite of their rarity, they represent an important stage in the evolution of galaxies, where the central giant is awakened, gaining mass, and potentially impacting the growth of its host galaxy," said Shenli Tang, a graduate student at the University of Tokyo and co-author of the study.

The American Academy of Sleep Medicine, a U.S. organisation representing sleep scientists and clinicians, has called for the eradication of the century-long practice of daylight saving time, in which clocks are moved an hour forward in the spring and returned back an hour in the winter. The twice-a-year transition, they argue, not only inconveniences everyone but also increases the risk of various health problems and motor vehicle accidents.

The organisation isn't the first group of scientists to rage against the tradition. Indeed, a growing number of studies over the years have found that the time shift can have modest but real negative effects on everything from sleep quality to the risk of heart attack and stroke. Just this January, for instance, a study found that the first week of daylight saving time in the spring was associated with a greater number of fatal car crashes; it also estimated that getting rid of it would have prevented more than 600 deadly accidents over a 22-year span.

"An abundance of accumulated evidence indicates that the acute transition from standard time to daylight saving time incurs significant public health and safety risks, including increased risk of adverse cardiovascular events, mood disorders, and motor vehicle crashes," the AASM notes in its statement, published Wednesday in the Journal of Clinical Sleep Medicine, which is run by the AASM.

Amazon's new fitness tracker 'Halo' takes technological intrusion to new levels, scanning the user's body and tracking the emotions in their voice. Even mainstream media coverage says the tech's privacy implications are troubling.

Like most fitness trackers, the retail behemoth's new wearable Halo monitors cardio activity, motion and sleep. Unlike most trackers, it also records body fat and voice tone - in ways that some users might find uncomfortably intrusive.

Not only can the device track your current body fat percentage (with the help of machine learning, no less!) by working with your smartphone's camera (red alert!) to photograph you in your underwear - it can show you your ideal self using a slider that fattens and slims the 3D model it creates. Endless hours of crushing inadequacy are at your fingertips! Amazon told the Verge it has built-in safeguards against encouraging eating disorders, explaining the slider doesn't dip below "dangerously low" levels of body fat and can't be used by customers under 18.

A widely circulated scientific study reported that Covid-19 causes long-term heart problems. Its authors have been forced to issue major corrections after they wildly miscalculated the risk, but the damage has already been done.

The scientific establishment wields a lot of power these days. The emergence of the novel coronavirus has elevated many career scientists and academics to positions of great influence, acting as advisors and commissars to governments on all things Covid-related. Which, it turns out, is everything. That is why it is so important that they conduct rational, unbiased research, and analyse all findings with great scepticism, taking nothing for granted.

New scientific paper demonstrates need for process-based risk assessment

A new scientific paper published in the journal Environmental Sciences Europe gives an overview of the risks associated with gene-editing procedures (new genetic engineering) for plants and animals. The risks are not restricted to the wide range of unintended effects that can be triggered by the process of gene editing. There are also risks associated with the intended biological characteristics generated through gene editing.

Gene-editing techniques, in particular those using the CRISPR/Cas "gene scissors", increase the possibilities and speed with which the genomes of plants and animals can be altered. It does not matter whether additional genes are introduced into the genome or not. Small genetic modifications are often performed in combination and can cause significant changes in metabolic pathways and plant composition. The study concludes that the novel, intended properties must be thoroughly tested, even if no additional genes are inserted.

The centre of the Milky Way is glowing. Yes, there's a big chonkin' black hole there, and it's a very energetic region, but there's an additional high-energy, gamma-ray glow, above and beyond the activity we know about, and it's something that's yet to be explained.

This glow is called the Galactic Center GeV Excess (GCE), and astronomers have been trying to figure it out for years. One hotly debated explanation is that the glow might theoretically be produced by the annihilation of dark matter - but new research is a nail in that idea's coffin.

In a series of exhaustive models that include recent developments in simulating the galactic bulge and other sources of gamma-ray emission in the galactic centre, a team of astrophysicists have ruled out dark matter annihilation as the source of the glow.

This finding, the team says, gives dark matter less room to hide - placing stronger constraints on its properties that could aid in future searches.