Lifeboat Foundation

Modern medicine forces bacteria to adapt: in response to antibiotic treatment, they either increase their fitness or die out. Whether a bacterial population survives or not depends on a combination of its genetics and environment—the antibiotic concentration—at a given moment. Now Suman Das of the University of Cologne, Germany, and colleagues simulate the effect on adaptation of an environment that is constantly changing [1]. Using a model that describes how slow-moving disordered systems respond to external forces, the researchers find that microbe evolution in changing drug concentrations exhibits hysteresis and memory formation. They use analytical methods and numerical simulations to connect these statistical physics concepts to bacterial drug resistance.

The team’s model examines changes in a bacterial population’s genetic sequences. By combining data on bacterial growth rates with statistical tools, the researchers describe how the bacterial genome can store information about both present and past drug concentrations. Their simulations start with a genetic sequence optimized for a certain antibiotic concentration. They then track how the sequence mutates when the concentration shifts to another value. When the concentration increases and then reduces to a lower value, the genetic route taken on the downward path depends on the changes on the upward path. How different the mutation routes are depends on the rate of concentration change.

The researchers find that this behavior mimics that of disordered systems driven by external forces, such as ferromagnetic materials subjected to magnetic fields or amorphous materials subjected to a shearing force. They say that while their approach focuses on the evolution of drug resistance, the framework can be adapted to other problems in evolutionary biology that involve changing environmental parameters.

Researchers produce analogues of hard-to-study quantum phenomena in a gas of strontium atoms near absolute zero.

Recently, researchers have begun using ultracold atomic gases to simulate phenomena that are difficult to study in their natural environments. Using electromagnetic fields, for example, they can orchestrate interatomic interactions that are analogous to interactions in condensed-matter systems, which they can then study with greater experimental control than the real examples allow. Now David Wilkowski of Nanyang Technological University in Singapore and colleagues use an ultracold atomic gas to simulate a condensed-matter system’s spin dynamics [1].

Wilkowski’s team cools a gas of strontium-87 atoms to 30 nK. Then, using three convergent laser beams, they drive the gas through various transitions until the atoms populate two so-called dark states, in which quantum mechanics forbids the atoms from undergoing spontaneous emission.

Researchers have demonstrated that a solid can exhibit an enhanced nonlinear optical phenomenon usually seen only in cold atomic gases.

Among the benefits brought about by the invention of the laser in the 1960s is the ability to generate light at an intensity great enough to produce nonlinear optical effects. Such nonlinear effects have entered daily use in applications that include infrared-to-visible-light wavelength conversion (in a green laser pointer, for example) and two-photon excitation (in fluorescence microscopes for observing biological living tissue). Now Corentin Morin of the École Normale Supérieure in Paris and colleagues address a third-order nonlinear process called the Kerr effect, which manifests as a change in a material’s refractive index when it is illuminated with light of different intensities [1]. The researchers demonstrate a giant Kerr nonlinearity in a solid, a state of matter that has, until now, exhibited only a weak Kerr effect. The result implies the possibility of scalable nonlinear quantum optics without the need of cold atoms in high vacuum.

The key to the discovery by Morin and colleagues is a quasiparticle called a Rydberg exciton, the understanding of which rests on two concepts. The first concept is the Rydberg series, which is the discrete energy-level structure available to an atom’s outermost electron, and which is indexed by the principal quantum number n. A high-lying Rydberg state has a large n and exhibits properties such as a large electron orbital radius, a long lifetime, and a large dipole moment, all of which are missing in the ground state. The second concept is a hydrogen-atom-like quasiparticle called an exciton—a negatively charged electron, photoexcited across a semiconductor’s band gap, Coulomb-bound to a positively charged hole left in the valence band.

Ancient Palmyra has gripped public imagination since its picturesque ruins were “rediscovered” in the seventeenth century by western travelers. The most legendary story of ancient Palmyra is that of Queen Zenobia, who was ruling over a thriving city in the Syrian Desert and dared to challenge the Roman Empire, but ultimately was defeated.

Her kingdom was subjugated, and the city was reduced to a small settlement without any wide-ranging importance. This has only recently been overshadowed by the catastrophic events of the Syrian Civil War that saw the archaeological site and the museum plundered and many monuments destroyed.

The technology, which has been tested in the lab, could ultimately be used for manufacturing and building in difficult-to-access or dangerous locations such as tall buildings or help with post-disaster relief construction, say the researchers.

3D printing is gaining momentum in the construction industry. Both on-site and in the factory, static and mobile robots print materials for use in construction projects, such as steel and concrete structures.

Continue reading “3D-printed drones work like bees to build and repair structures while flying” »

A study led by Durham University’s Fetal and Neonatal Research Lab, UK, took 4D ultrasound scans of 100 pregnant women to see how their unborn babies responded after being exposed to flavors from foods eaten by their mothers.

Researchers looked at how the fetuses reacted to either carrot or kale flavors just a short time after the flavors had been ingested by the mothers.

Fetuses exposed to carrot showed more “laughter-face” responses while those exposed to kale showed more “cry-face” responses.

From the same mind whose research propelled the notion that “sitting too much is not the same as exercising too little,” comes a groundbreaking discovery set to turn a sedentary lifestyle on its ear: The soleus muscle in the calf, though only 1% of your body weight, can do big things to improve the metabolic health in the rest of your body if activated correctly.

And Marc Hamilton, professor of Health and Human Performance at the University of Houston, has discovered such an approach for optimal activation—he’s pioneering the “soleus pushup” (SPU) which effectively elevates muscle metabolism for hours, even while one is sitting. The soleus, one of 600 muscles in the human body, is a posterior leg muscle that runs from just below the knee to the heel.

Continue reading “Researcher discovers a muscle that can promote glucose and fat burning to fuel metabolism for hours while sitting” »

Researchers investigated the polarization-dependence of the force exerted by circularly polarized light (CPL) by performing optical trapping of chiral nanoparticles. They found that left-and right-handed CPL exerted different strengths of the optical gradient force on the nanoparticles, and the D-and L-form particles are subject to different gradient force by CPL. The present results suggest that separation of materials according to their handedness of chirality can be realized by the optical force.

Chirality is the property that the structure is not superimposable on its mirrored image. Chiral materials exhibit the characteristic feature that they respond differently to left-and right-circularly polarized light. When matter is irradiated with strong laser light, optical force is exerted on it. It has been expected theoretically that the optical force exerted on chiral materials by left-and right-circularly polarized light would also be different.

Continue reading “Differentiating right- and left-handed particles using the force exerted” »

Florida’s “silent” flying dish-rack, powered by ionic propulsion, is on track for commercial rollout in 2024, according to Undefined Technologies, which has released new outdoor flight test video. We remain curious, but unconvinced it’ll be viable.

The “Silent Ventus” drone doesn’t use propellers to fly. Instead, its entire broad structure creates two stacked grids of electrodes, designed to create high-voltage electric fields that can ionize the oxygen and nitrogen molecules in the air, freeing electrons to give them a positive charge, and then propelling these downward to create an “ionic wind” that can produce thrust.

Continue reading “Undefined claims 4.5-min flight for its ‘silent’ ion-propulsion drone” »