You et al. show that size-dependent proteomic remodeling originates at the transcriptomic level. Protein and mRNA turnover contribute minimally to the proteomes of large cells, implicating transcription as the primary driver of size-dependent gene expression. Moreover, mRNA synthesis scales with size through a proportional increase in burst length.
MIT researchers have demonstrated a low-cost design of specialized electronic nozzles, called triaxial electrospray emitters, that could be used to manufacture time-release drug-delivery particles or self-healing materials efficiently and at scale.
Triaxial electrospray emitters use electricity to precisely dispense three liquids from microscopic nozzles to generate a steady stream with three distinct fluid layers. The liquid forms multilayered droplets, which can solidify into layered microparticles.
For instance, an array of triaxial electrospray emitters can be used to make three-layer drug-delivery nanoparticles. The outer layer might slowly erode in the stomach, revealing a second material that controls the release of a core material, which delivers medicine to a specific area of the intestines.
A model that captures how crater-forming impacts redistribute lunar dirt will help researchers read the cosmic timeline found in samples returned from the Moon.
The Moon’s soil preserves signatures of the solar wind, cosmic rays, and episodic stellar events, but frequent meteorite strikes scramble what would otherwise be a neatly layered record of cosmic history. Researchers have now developed a mathematical model that accounts for this scrambling effect in lunar soil [1]. The model can predict the depths and concentrations of radioactive isotopes originating from astrophysical events hundreds of light-years away. It provides a guide for future lunar sampling missions that will search for evidence of specific events in our Solar System’s history.
Samples returned from the Apollo missions suggest that irradiation and the solar wind alter the lunar surface soil’s chemistry and physical appearance as it ages. In addition, nearby supernovae emit radioactive isotopes, including short-lived ones such as iron-60. Meanwhile, meteorite impacts mix all this surface material and gradually transport it deep into the soil or upward from below in a process known as impact gardening. But models of this transport often fail to capture key features observed in the Apollo samples. For example, analysis of core samples (long, vertical cylinders of soil) suggest that, in some cases, the concentrations of certain isotopes have much steeper depth dependence than models predict.
Often, humans and other animals seek information that can help them complete tasks and attain desired rewards. In some cases, however, they seek information driven simply by curiosity and a desire to obtain knowledge for its own sake, even if it does not lead to external rewards.
Researchers at Columbia University, Harvard Medical School and Johns Hopkins University recently created a new experimental paradigm for studying the neural processes associated with curiosity and the desire for knowledge in mice. This paradigm, outlined in a paper in Nature Neuroscience, allowed them to gain new insights into how the brain represents the value of information regardless of physical rewards.
“We wanted to understand the neural basis of our desire for knowledge—why we read books, explore, and have such a strong drive to find things out,” Jennifer J. Bussell, first author of the paper, told Medical Xpress. “Earlier experiments had suggested that the brain responds to information as if it is a reward, to such an extent that even the exact same neurons in the brain’s reward centers respond to predictions of juice and information.”
When one mentions “waves,” we immediately think of a perturbation that propagates. This applies to waves on the shore, sound waves in the air or electromagnetic waves that we use to transmit information via optical fibers. The same idea of propagating perturbations applies to gravitational waves (GWs), which entered the mainstream media a decade ago after their first direct detection. These are perturbations of the elastic fabric that we are all embedded in, called spacetime.
It is as if waves do not like to stay still; on the contrary, they really like to move from the moment they are created. However, there are some instances in which perturbations remain spatially localized, ignoring their propagating counterparts entirely, even when sharing the same space. These forever localized perturbations are called BICs (from bound states in the continuum). I discuss these in a new article published in Physica Scripta.
Basic biology courses teach that cells contain organelles—such as the nucleus, mitochondria and Golgi apparatus—set apart by lipid membranes to get things done. Recent cell biology research has revealed another organizational principle at work in cells across all orders of biology.
“Proteins and nucleic acids spontaneously organize themselves into blobs called condensates,” said Eric Dufresne, professor of physics in the College of Arts and Sciences and of materials science and engineering at Cornell Duffield College of Engineering, who is working to understand how condensates work.
Droplet-like condensates form and dissolve as cells need them, bringing selected proteins, RNA and other molecules together to coordinate biochemical reactions, said Takumi Matsuzawa, a postdoctoral researcher in physics. “Their timely formation and dissolution are essential for normal cellular function, and disruptions to this process have been linked to neurodegenerative diseases,” including Alzheimer’s and Parkinson’s.
Astronomers have proposed a new explanation for the mysterious Cygnus Bubble, a vast cloud of ultra-high-energy gamma rays stretching thousands of light-years across the sky. While the bubble has generally been linked to the Cygnus X star-forming region, the new study argues that a microquasar more naturally explains its highest-energy emission. The results were published in a paper in The Astrophysical Journal Letters on July 21.
For years, astronomers have puzzled over the sources of the highest-energy cosmic rays in our galaxy—particles accelerated to a quadrillion electron volts, or a petaelectronvolt (PeV; that’s 15 zeros after 1). These sources are called Galactic PeVatrons, and they are notoriously hard to pin down. In principle, all kinds of astrophysical objects violent enough to accelerate particles to extreme energies could be PeVatrons: supernova remnants, pulsar wind nebulae, star clusters or binary star systems.
The accelerated particles travel outward and light up with ultra-high-energy gamma rays wherever they eventually slam into ambient gas, sometimes hundreds to thousands of light-years from their true source. One of the most striking gamma-ray structures in the sky, the “Cygnus Bubble,” has long been attributed to a nearby cluster of massive, young stars in the Cygnus X star-forming region, some 4,600 light-years away.
Latin squares are arrangements of symbols in a grid in which every symbol appears exactly once in each row and column. These symbol arrangements, which were first studied more than three centuries ago, are now widely used to optimize experimental designs and develop secure cryptographic systems, puzzles or other complex combinatorial structures.
In 1782, the Swiss mathematician Leonhard Euler devised a renowned mathematical problem based on Latin squares, known as the 36 officers problem. This problem entails arranging 36 officers from six regiments and six ranks in a 6-by-6 square grid, ensuring that every row and column contains one officer from each regiment and each rank.
In the centuries after Euler introduced this problem, mathematicians showed that it could not be solved using classical approaches. More recently, theorists introduced quantum versions of this problem, replacing the individual symbols in ordinary Latin squares with mathematical descriptions of possible quantum system states.
A new pathway has opened for controlling the rotation direction of light simply by changing how molecules are arranged, without having to synthesize complex new materials. Circularly polarized light is a special form of light that travels while rotating like a pinwheel to the left or right. Because different rotation directions can carry different information, it is drawing attention as a key light source for next-generation displays, optical communications and security technologies.
KAIST researchers have developed a platform technology that arranges symmetric molecules into “microscopic pinwheels,” enabling circularly polarized light with a desired rotation direction. The research results were published in the Nature Communications.