Well-defined Direction Research Articles

Charged current weak production of Δ(1232) induced by electrons and positrons

The charged current weak production of Δ(1232) from the free proton target induced by the electron/positron in the intermediate energy range corresponding to the beam energy available at JLab and Mainz, has been studied. The results for the differential scattering cross section dσdQ2, the angular distribution dσdΩΔ, and the total scattering cross section σ(Ee) for both the electron and positron induced processes are presented, for the various energies in the range of 0.5–4 GeV. The cross section σ(Ee) is found to be of the order of 10−39 cm2 for the electron/positron energies in the few GeV range. The availability of electron/positron beams having well-defined energy and direction with very high luminosity of the order of 1038–1039 cm−2 sec−1, makes it possible to observe the weak charged current production of Δ(1232) and determine the axial vector form factors CiA(Q2);(i=3–5). The sensitivity of the differential cross section dσdQ2 to the subdominant form factors C3A(Q2) and C4A(Q2) is found to be strong enough, especially in the low Q2 region, which can be used to determine them phenomenologically and to test the various theoretical models proposed to calculate them. Published by the American Physical Society 2024

Chimera states and information transfer in interacting populations of map-based neurons

We investigate the synchronization behavior and the emergence of chimera states in a system of two interacting populations of maps possessing chaotic neural-like dynamics. We characterize four collective states on the space of coupling parameters of the system: complete synchronization, generalized synchronization, chimera states, and incoherence. We quantify the information exchange between the two neuron populations in chimera states. We have found a well-defined direction of the flow of information in chimera states, from the desynchronized population to the synchronized one. The incoherent population functions as a driver of the coherent neuron population in a chimera state. This feature is independent of the population sizes or population partitions. Our results yield insight into the communication mechanisms arising in brain processes such as unihemispheric sleep and epileptic seizures that have been associated to chimera states.

Nonreciprocal feedback induces migrating oblique and horizontal banded vegetation patterns in hyperarid landscapes

In hyperarid environments, vegetation is highly fragmented, with plant populations exhibiting non-random biphasic structures where regions of high biomass density are separated by bare soil. In the Atacama Desert of northern Chile, rainfall is virtually nonexistent, but fog pushed in from the interior sustains patches of vegetation in a barren environment. Tillandsia landbeckii, a plant with no functional roots, survives entirely on fog corridors as a water source. Their origin is attributed to interaction feedback among the ecosystem agents, which have different spatial scales, ultimately generating banded patterns as a self-organising response to resource scarcity. The interaction feedback between the plants can be nonreciprocal due to the fact that the fog flows in a well-defined direction. Using remote sensing analysis and mathematical modelling, we characterise the orientation angle of banded vegetation patterns with respect to fog direction and topographic slope gradient. We show that banded vegetation patterns can be either oblique or horizontal to the fog flow rather than topography. The initial and boundary conditions determine the type of the pattern. The bifurcation diagram for both patterns is established. The theoretical predictions are in agreement with observations from remote sensing image analysis.

Adenosine Stimulates Beating of Neonatal Brain-Derived Cilia through Adenosine A2B Receptor on the Cilia and Activation of Protein Kinase A Pathway.

Motile cilia in the ependymal cells that line the brain ventricles play pivotal roles in cerebrospinal fluid (CSF) flow in well-defined directions. However, the substances and pathways which regulate their beating have not been well studied. Here, we used primary cultured cells derived from neonatal mouse brain that possess motile cilia and found that adenosine (ADO) stimulates ciliary beating by increasing the ciliary beat frequency (CBF) in a concentration-dependent manner, with the ED50 value being 5 µM. Ciliary beating stimulated by ADO was inhibited by A2B receptor (A2BR) antagonist MRS1754 without any inhibition by antagonists of other ADO receptor subtypes. The expression of A2BR on the cilia was also confirmed by immunofluorescence. The values of CBF were also increased by forskolin, which is an activator of adenylate cyclase, whereas they were not further increased by the addition of ADO. Furthermore, ciliary beating was not stimulated by ADO in the presence of a protein kinase A (PKA) inhibitors. These results altogether suggest that ADO stimulates ciliary beating through A2BR on the cilia, and activation of PKA.

Temperature Intermittent Structures in the Fast Solar Wind

In the solar wind turbulence, proton temperature fluctuations are highly intermittent, especially at small scales in the inertial range. This phenomenon may contain information about solar wind intermittent heating. However, the physical nature of the temperature intermittency is not yet clear. Based on the measurements from Solar Orbiter between 2020 September and 2022 September, we identify 185 temperature intermittent structures at the scale of 24 s with well-defined minimum variance direction in the fast solar wind and study the nature and kinetic effects of them. According to the variations of proton temperature, the intermittent structures are classified into four types, including temperature bump, step, dip, and chain. When considering the magnetic field configuration together with other plasma properties, we find that, among the bump cases, 46 of them are linear magnetic holes (LMHs) that are mainly related to mirror-mode (MM) instability, and 43 of them are current sheets (CSs) with local temperature enhancement. The step cases are found to be associated with shock-like structures (13 cases) and tangential discontinuities (eight cases) that separate two different parcels of plasma. For the dip cases, 21 of them could be associated with the MM instability, and the rest of the 16 ones may prefer soliton scenario. The 38 chain cases are identified as compressive vortex-like structures and a mixture of LMHs and CSs. These results will help to further understand the intermittent dissipation process in the solar wind turbulence.

„Mira circa nos” — kanonizacja Franciszka czy Zakonu?

In the papal letter “Mira circa nos”, published on the occasion of the canonization of Francis of Assisi in July 1226, Gregory IX, using many references to biblical figures and events, presented to the believers some selected elements of his spiritual profile. These elements not only provided insight into the profile of the new saint but, also by referring to the community of Friars Minor he had founded, marked out for them a well-defined direction of activity in the Church. This article analyzes and describes two very characteristic biblical references by means of which Gregory IX presents St. Francis as a zealous preacher, reformer and apostle sent by God to work in the Church, leading others along the path of salvation. The references to the workers of the eleventh hour from Jesus’ parable and to the biblical sisters Rachel and Leah to strongly emphasize the value and need of apostolic life, read in the context of the Church’s ongoing reform and the texts of earlier authors, show a clear trace of the Holy See’s policy toward the order founded by Francis.

Self-Propulsion by Directed Explosive Emulsification.

An active droplet system, programmed to repeatedly move autonomously at a specific velocity in a well-defined direction, is demonstrated. Coulombic energy is stored in oversaturated interfacial assemblies of charged nanoparticle-surfactants by an applied DC electric field and can be released on demand. Spontaneous emulsification is suppressed by an increase in the stiffness of the oversaturated assemblies. Rapidly removing the field releases the stored energy in an explosive event that propels the droplet, where thousands of charged microdroplets are ballistically ejected from the surface of the parent droplet. The ejection is made directional by a symmetry breaking of the interfacial assembly, and the combined interaction force of the microdroplet plume on one side of the droplet propels the droplet distances tens of times its size, making the droplet active. The propulsion is autonomous, repeatable, and agnostic to the chemical composition of the nanoparticles. The symmetry-breaking in the nanoparticle assembly controls the microdroplet velocity and direction of propulsion. This mechanism of droplet propulsion will advance soft micro-robotics, establishes a new type of active matter, and introduces new vehicles for compartmentalized delivery.

Symmetry breaking at a topological phase transition

Spontaneous symmetry breaking is a foundational concept in physics. In condensed matter, it characterizes conventional continuous phase transitions but is absent at topological phase transitions such as the Berezinskii–Kosterlitz–Thouless (BKT) transition—as in the BKT case the expected norm (i.e., the magnitude) of the U(1) order parameter vanishes in the thermodynamic limit at all nonzero temperatures. Phenomena consistent with low-temperature broken symmetry have been observed, however, in many different BKT experiments. Examples include recent experiments on superconducting films and the seminal work on two-dimensional arrays of Josephson junctions. While the inaccessibility of the above thermodynamic limit partially explains this paradox in finite systems, the full dynamical framework of symmetry breaking at the BKT transition remains unresolved. Here we provide this by introducing the broader concept of . This encompasses both spontaneous symmetry breaking and the BKT case by allowing the expected norm of the order parameter to go to zero in the thermodynamic limit, provided its directional phase fluctuations are asymptotically smaller. We demonstrate this asymptotically slow directional mixing in the low-temperature BKT phase. This explicitly shows that the order parameter arbitrarily chooses some well-defined direction in the thermodynamic limit, predicting negligible phase fluctuations compared to the expected norm in arbitrarily large experimental BKT systems. Our results provide a model for directional mixing timescales across the diverse array of experimental BKT systems. We suggest various experiments. Published by the American Physical Society 2024

Ring-shaped nanomotors of heterojuncted carbon boron-nitride nanotubes

Constructing a nanomotor, especially one with simple configurations and good performance, plays a crucial role in the field of nanotechnology. Here, we present a prototype design of a ring-shaped nanomotor with carbon boron-nitride heterojunction nanotubes as the stator. Molecular dynamics simulations show that, when thermal gradients are applied on the stator, an inner carbon nanotube, or contented water, can be driven to move inside the stator with well-defined directions and speeds. The driving mechanism is attributed to the asymmetric thermophoretic force due to asymmetric configurations of the stator, which is further confirmed by an analytical model. This work presents a primary study on ring-shaped nanomotors and may have a great potential in nanomachines including nanogenerators.

Multiple channelling single-photon emission with scattering holography designed metasurfaces

Channelling single-photon emission in multiple well-defined directions and simultaneously controlling its polarization characteristics is highly desirable for numerous quantum technology applications. We show that this can be achieved by using quantum emitters (QEs) nonradiatively coupled to surface plasmon polaritons (SPPs), which are scattered into outgoing free-propagating waves by appropriately designed metasurfaces. The QE-coupled metasurface design is based on the scattering holography approach with radially diverging SPPs as reference waves. Using holographic metasurfaces fabricated around nanodiamonds with single Ge vacancy centres, we experimentally demonstrate on-chip integrated efficient generation of two well-collimated single-photon beams propagating along different 15° off-normal directions with orthogonal linear polarizations.

Double Cation-π Directed Two-Dimensional Metallacycle-Based Hierarchical Self-Assemblies for Dual-Mode Catalysis.

Hierarchical self-assembly of Pt(II) metallacycles for the construction of functional materials has received considerable research interest, owing to their potential to meet increasing complexity and functionality demands while being based on well-defined scaffolds. However, the fabrication of long-range-ordered Pt(II) metallacycle-based two-dimensional hierarchical self-assemblies (2D HSAs) remains a challenge, primarily because of the limitations of conventional orthogonal noncovalent interaction (NCI) motifs and the intrinsic characteristics of Pt(II) metallacycles, making the delicate self-assembly processes difficult to control. Herein, we prepare well-regulated Pt(II)-metallacycle-based 2D HSAs through a directed strategy involving double cation-π interactions derived from C3-symmetric hexagonal Pt(II) metallacycles and C2-symmetric sodium phenate monomers. Spatially confined arrays of planar Pt(II) metallacycles and the selective growth of self-assemblies at desired locations are achieved by employing strong cation-π driving forces with well-defined directionality as the second orthogonal NCI, realizing the bottom-up, three-stage construction of Pt(II)-metallacycle-based 2D HSAs. The resultant 2D HSAs are applied as dual-mode catalysis platforms, which are loaded with two different nanocatalysts, one promoting catalytic oxidation and the other promoting photocatalytic reduction.

Inverted Sedimentation of Active Particles in Unbiased ac Fields.

Gaining control over the motion of active particles is crucial for applications ranging from targeted cargo delivery to nanomedicine. While much progress has been made recently to control active motion based on external forces, flows, or gradients in concentration or light intensity, which all have a well-defined direction or bias, little is known about how to steer active particles in situations where no permanent bias can be realized. Here, we show that ac fields with a vanishing time average provide an alternative route to steering active particles. We exemplify this route for inertial active particles in a gravitational field, observing that a substantial fraction of them persistently travels in the upward direction upon switching on the ac field, resulting in an inverted sedimentation profile at the top wall of a confining container. Our results offer a generic control principle that could be used in the future to steer active motion, direct collective behaviors, and purify mixtures.

Highly directional single-photon source

Abstract Single-photon emitters are a pivotal element in quantum technologies, but the generation of single photons along well-defined directions generally involves sophisticated configurations. Here, we propose a photon source capable of generating single photons with high efficiency along guided modes. Specifically, we consider a quantum emitter placed in a periodically patterned linear waveguide. The latter is designed to host a single guided mode over the spectral range of interest and display a divergence in the photonic density of states at an emission wavelength close to the period. Photons are preferentially emitted along the waveguide near that spectral region. We predict that nearly all of the emission can be made to occur along the waveguide with a reduction in the temporal uncertainty by two orders of magnitude. Our study opens a conceptually new direction in the production of single photons with a high degree of directionality and reduced temporal uncertainty.

Ballistic transport of a polariton ring condensate with spin precession

It is now routine to make Bose-Einstein condensates of polaritons with long enough lifetime and low enough disorder to travel ballistically for hundreds of microns in quasi-one-dimensional (1D) wires. We present observations of a nonequilibrium polariton condensate injected at one point in a quasi-1D ring, with a well-defined initial velocity and direction. A clear precession of the circular polarization is seen, which arises from an effective spin-orbit-coupling term in the Hamiltonian. Our theoretical model accurately predicts the experimentally observed behavior and shows that ``zitterbewegung'' behavior plays a role in the motion of the polaritons.

A unified regularized variational cohesive fracture theory with directional energy decomposition

In this paper, the cohesive fracture is revisited as an energy minimization problem. The energy functional is rigorously derived based on a pair of integral transformations and a novel directional energy decomposition method. The resulting description of the regularized crack is perfectly suitable for cohesive fracture. A well-defined crack direction is associated with each material point. The resulting constitutive relation shows that a damage-induced material orthotropy within the regularized crack is introduced in this theory, which is suitable for cohesive fracture. The proposed method can implement an arbitrarily given mixed-mode cohesive law. The tensile and shear fracture modes are covered in a unified manner and controlled by the tensile-to-shear strength ratio. These theoretical results are presented with detailed proofs and verified numerically by some representative examples involving tension, shear, and compression.

Methods and stages of creation and practical use of red white-belt meat pigs

It is known that the peoples of different countries and continents have always sought knowledge, enrichment of their culture and improving living standards. But no matter how the world is broken, no matter how the system is built - food has been and will always remain the first ingredient of independence and development of any state.
 And if there are alternative solutions in overcoming other topical and economically important problems, there are no alternative ones in the implementation of food issues. Almost everyone knows that one of the main indicators of human quality is the use of animal protein. In the developed countries of the world it is consumed on average per capita in the range of 52-56 g per day, which is good, but below the scientifically sound dietary norms. As for developing countries, this figure is 12-16 g, that is 4-5 times less than the norm. According to statistics, in recent years the world has produced approximately 342 million tons of meat annually, of which about 36.4% was poultry, 35.2% - pork, 21.8% - beef, 4.4 % - lamb and goat and 2, 2% for other species. According to experts, pork will remain in the lead. And why is this so? But thanks to the extremely important biological and economic characteristics of pigs: multiplicity, precocity, omnivorous, economical use of feed, unpretentiousness to the conditions of detention, as well as the ability to cook pork many different delicious dishes. [1]. In Ukraine, pig farming has long been considered, so to speak, a national branch of agricultural production and has almost never been unprofitable for a caring owner. There was a time when pork accounted for 58.7 percent of total meat production. Long-term observations record periods of intensive development of pig breeding and its catastrophic decline. And yet, despite periodic economic cataclysms, focused research on the theory and practice of the industry continued, and the painstaking long-term work of pig scientists and practitioners, as a rule, ended with the latest advances. Long-term observations record periods of intensive development of pig breeding and its catastrophic decline. And yet, despite periodic economic cataclysms, focused research on the theory and practice of the industry continued, and the painstaking long-term work of pig scientists and practitioners, as a rule, ended with the latest advances.
 In order to maintain this fact, we recall that in all farms of Ukraine in 1913 there were 8.5 million pigs; in 1940–9.2; in 1944–2.9; in 1950 –7.0; in 1971–21.4 million heads, it should be added that in 1989 the country produced 1,576,000 tons of pork at slaughter weight, or 31 kg per capita, which fully complied with existing scientifically sound medical standards of human nutrition. [3]. Unfortunately, it should also be noted that at the beginning of 2022 the number of pigs in the country does not exceed 8 million.
 It is known that the direction of pig productivity is determined by the social order in the period of creation of breeds, as well as the place of their use in regional breeding systems. Thus, the breeds that were bred in our country in the 40-60 years of the last century, were characterized mainly by a well-defined sebaceous direction of productivity. This can be confirmed by the creation of Ukrainian steppe white, Myrhorod and Ukrainian steppe speckled rocks. In the following decades, with the increase in demand for pork, the improvement of previously created breeds was carried out in the direction of improving the meat of carcasses, reducing the fattening period and reducing costs per unit of growth without deteriorating pork quality. [2]. Due to the lack of domestic meat genotypes, a special role in crossbreeding and hybridization was given to the breeds of Landrace, Pietren, Duroc, Wales and Hampshire imported from abroad. However, imported breeds, firstly, were unable to meet the high needs of our pigs in high-quality meat boar herds and, secondly, the efficiency of importing breeding stock was low due to its slow adaptation to different climatic conditions. and economic features of our then very large state. Therefore, it is expedient to breed new domestic genotypes of pigs, which would meet the demand of mass pig breeding in the meat population and reduce the pressure of imports on the domestic market of breeding pigs.
 In accordance with the above, in the eighties of the last century Poltava Research Institute of Pig breeding began work to create a new genotype (breed) of pigs, which would be characterized by good reproductive ability, high fattening and meat qualities, and which could be used as a parent shape in combination with existing breeds and their mixtures. The work to create a new parent breed was relevant and had economic significance. [3].

Transverse spin and the hidden vorticity of propagating light fields.

Spatially inhomogeneous fields of electromagnetic guided modes exhibit a complex of extraordinary dynamical properties such as polarization-dependent transverse momentum, helicity-independent transverse spin, spin-associated non-reciprocity and unidirectional propagation, etc. Recently, the remarkable relationship has been established between the spin and propagation features of such fields, expressed through the spin-momentum equations [Proc. Natl. Acad. Sci. USA118, e2018816118 (2021) PNASA60027-842410.1073/pnas.2018816118] connecting the wave spin with the curl of momentum. Here, the meaning, limitations, and specific forms of this correspondence are further investigated, involving physically transparent and consistent examples of paraxial light fields, plane-wave superpositions, and evanescent waves. The conclusion is inferred that the spin-momentum equation is an attribute of guided waves with a well-defined direction of propagation, and it unites the helicity-independent "extraordinary" transverse spin with the spatially inhomogeneous longitudinal field momentum (energy flow) density. Physical analogies with the layered hydrodynamic flows and possible generalizations for other wave fields are discussed. The results can be useful in optical trapping, manipulation, and data processing techniques.

Mechanical attributes and wave propagation characteristics of TPMS lattice structures

The current work investigates the mechanical properties and wave propagation characteristics of sheet and solid type triply periodic minimal surface structures (TPMSs), including the gyroid, primitive, diamond, and IWP lattices over a broad range of relative density values. Their effective Young's and shear moduli, as well as their Poisson's ratio are characterized for relative densities in the range 0.15–0.6. It is found that higher-order polynomial expressions can robustly capture the entire metamaterial design space for both sheet and solid-type structures, with the mechanical performance of solid-type TPMS lattices to substantially differ from the corresponding sheet-type designs. The numerical results are experimentally verified using 3D-printed TPMS specimens. The static attributes are thereafter used to investigate the effect of the relative density and propagating direction on the long-wavelength wave characteristics of sheet and solid type TPMS lattices. It is found that the shear and longitudinal phase velocities differ the most and least in well-defined propagation directions with an in-plane angular difference of 45° for both sheet and solid-type TPMS lattices. Moreover, the primitive-type TPMS lattices are found to exhibit the highest anisotropy among the considered structures.

Light-driven microdrones.

When photons interact with matter, forces and torques occur due to the transfer of linear and angular momentum, respectively. The resulting accelerations are small for macroscopic objects but become substantial for microscopic objects with small masses and moments of inertia, rendering photon recoil very attractive to propel micro- and nano-objects. However, until now, using light to control object motion in two or three dimensions in all three or six degrees of freedom has remained an unsolved challenge. Here we demonstrate light-driven microdrones (size roughly 2 μm and mass roughly 2 pg) in an aqueous environment that can be manoeuvred in two dimensions in all three independent degrees of freedom (two translational and one rotational) using two overlapping unfocused light fields of 830 and 980 nm wavelength. To actuate the microdrones independent of their orientation, we use up to four individually addressable chiral plasmonic nanoantennas acting as nanomotors that resonantly scatter the circular polarization components of the driving light into well-defined directions. The microdrones are manoeuvred by only adjusting the optical power for each motor (the power of each circular polarization component of each wavelength). The actuation concept is therefore similar to that of macroscopic multirotor drones. As a result, we demonstrate manual steering of the microdrones along complex paths. Since all degrees of freedom can be addressed independently and directly, feedback control loops may be used to counteract Brownian motion. We posit that the microdrones can find applications in transport and release of cargos, nanomanipulation, and local probing and sensing of nano and mesoscale objects.

Modification of monolayer 1T-VSe2 by selective deposition of vanadium and tellurium

Hetero-structures of transition metal dichalcogenide (TMD) layers offer vast possibilities of new materials properties. The growth behaviors of such TMD hetero-structures can be complex. In this study, we report the structure modification of a VSe2 monolayer by the molecular beam deposition of Te, V, or both. With a typical growth temperature of 300 °C and a nominal flux rate, we found that Te deposition leaves the VSe2 intact. Vanadium deposition, in contrast, leads to small clusters ordered in stripes along well-defined directions. The charge density wave symmetry of monolayer VSe2 surprisingly changes in small regions enclosed by such vanadium stripes. With V and Te co-deposition, a dramatic change of the monolayer surface structure to a (2 × 1) ordered phase is observed. This study illustrates the unexpected complexities involved in preparing even a simple bilayer TMD hetero-structure, such as VTe2/VSe2.