Preferred Direction Research Articles

Rhesus monkeys learn to control a directional-key inspired brain machine interface via bio-feedback.

Brain machine interfaces (BMI) connect brains directly to the outside world, bypassing natural neural systems and actuators. Neuronal-activity-to-motion transformation algorithms allow applications such as control of prosthetics or computer cursors. These algorithms lie within a spectrum between bio-mimetic control and bio-feedback control. The bio-mimetic approach relies on increasingly complex algorithms to decode neural activity by mimicking the natural neural system and actuator relationship while focusing on machine learning: the supervised fitting of decoder parameters. On the other hand, the bio-feedback approach uses simple algorithms and relies primarily on user learning, which may take some time, but can facilitate control of novel, non-biological appendages. An increasing amount of work has focused on the arguably more successful bio-mimetic approach. However, as chronic recordings have become more accessible and utilization of novel appendages such as computer cursors have become more universal, users can more easily spend time learning in a bio-feedback control paradigm. We believe a simple approach which leverages user learning and few assumptions will provide users with good control ability. To test the feasibility of this idea, we implemented a simple firing-rate-to-motion correspondence rule, assigned groups of neurons to virtual "directional keys" for control of a 2D cursor. Though not strictly required, to facilitate initial control, we selected neurons with similar preferred directions for each group. The groups of neurons were kept the same across multiple recording sessions to allow learning. Two Rhesus monkeys used this BMI to perform a center-out cursor movement task. After about a week of training, monkeys performed the task better and neuronal signal patterns changed on a group basis, indicating learning. While our experiments did not compare this bio-feedback BMI to bio-mimetic BMIs, the results demonstrate the feasibility of our control paradigm and paves the way for further research in multi-dimensional bio-feedback BMIs.

Weld appearance, microstructure evolution and microhardness of welded joint in the TC4 additive manufactured component TIG welding

In this work, TC4 titanium alloy CMT additive thin-walled components is selected as base metal to study the weld formation, microstructure evolution, and microhardness of TIG welded joint. The results showed that the thin-walled components could obtain a good formation after TIG welding. The weld seam was mainly consisted of equiaxed and columnar of β grain. The maximum texture intensity of β phase in the weld surface was only 10.746. Therefore, there was no obvious preferred growth direction in the weld seam. The heat affected bands (HAB) in the zone of weld seam was disappeared due to the base metal no undergone multiple heating cycles after melting. In the weld cross-section and weld surface, the average hardness of base metal is about 334.5 HV and 358.8 HV, respectively. The hardness of weld seam was greater than that of the base metal. The hardness of weld surface was greater than that of weld cross-section. The change of hardness of welded joint was mainly caused by β grain size and α phase.

Comparison of head direction cell firing characteristics across thalamo-parahippocampal circuitry.

Head direction (HD) cells, which fire persistently when an animal's head is pointed in a particular direction, are widely thought to underlie an animal's sense of spatial orientation and have been identified in several limbic brain regions. Robust HD cell firing is observed throughout the thalamo-parahippocampal system, although recent studies report that parahippocampal HD cells exhibit distinct firing properties, including conjunctive aspects with other spatial parameters, which suggest they play a specialized role in spatial processing. Few studies, however, have quantified these apparent differences. Here, we performed a comparative assessment of HD cell firing characteristics across the anterior dorsal thalamus (ADN), postsubiculum (PoS), parasubiculum (PaS), medial entorhinal (MEC), and postrhinal (POR) cortices. We report that HD cells with a high degree of directional specificity were observed in all five brain regions, but ADN HD cells display greater sharpness and stability in their preferred directions, and greater anticipation of future headings compared to parahippocampal regions. Additional analysis indicated that POR HD cells were more coarsely modulated by other spatial parameters compared to PoS, PaS, and MEC. Finally, our analyses indicated that the sharpness of HD tuning decreased as a function of laminar position and conjunctive coding within the PoS, PaS, and MEC, with cells in the superficial layers along with conjunctive firing properties showing less robust directional tuning. The results are discussed in relation to theories of functional organization of HD cell tuning in thalamo-parahippocampal circuitry.

Steering droplets on substrates with plane-wave wettability patterns and deformations.

Motivated by strategies for targeted microfluidic transport of droplets, we investigate how sessile droplets can be steered toward a preferred direction using travelling waves in substrate wettability or deformations of the substrate. To perform our numerical study, we implement the boundary-element method to solve the governing Stokes equations for the fluid flow field inside the moving droplet. In both cases we find two distinct modes of droplet motion. For small wave speed the droplet surfs with a constant velocity on the wave, while beyond a critical wave speed a periodic wobbling motion occurs, the period of which diverges at the transition. These observation can be rationalized by the nonuniform oscillator model and the transition described by a SNIPER bifurcation. For the travelling waves in wettability the mean droplet velocity in the wobbling state decays with the inverse wave speed. In contrast, for travelling-wave deformations of the substrate it is proportional to the wave speed at large speed values since the droplet always has to move up and down. To rationalize this behavior, the nonuniform oscillator model has to be extended. Since the critical wave speed of the bifurcation depends on the droplet radius, this dependence can be used to sort droplets by size.

Visualizing the Movement of the Celtic Stone as High School Students Activity

The Celtic Stone (also known as a rattleback) is a semi-ellipsoidal shaped solid object which when spun rotates on its axis in a preferred direction. If spun in the opposite direction, it goes to the stop and reverses its spin to the preferred direction. As the movement of the stone is multidirectional it is a challenge to perform quantitative measurements of its motion characteristics. The work presents the experimental set-up and the procedure for collecting date of a rattleback motion as the high school students activity. Proposals for specific student actions and their benefits for learning were described in connection with the results obtained. Some preliminary results of video measurements performed with a specific metal rattleback and meant to visualize its motion are reported. Attempts to compare the results with predictions based on the numerical model of the situation are undertaken. The advantages and disadvantages of the measurement system are presented and discussed.

Testing the cosmological principle with the Pantheon+ sample and the region-fitting method

The cosmological principle is fundamental to the standard cosmological model. It assumes that the Universe is homogeneous and isotropic on very large scales. As the basic assumption, it must stand the test of various observations. In this work, we investigated the properties of the Pantheon+ sample, including redshift distribution and position distribution, and we give its constraint on the flat ΛCDM model: Ωm = 0.36 ± 0.02 and H0 = 72.83 ± 0.23 km s−1 Mpc−1. Then, using the region fitting (RF) method, we mapped the all-sky distribution of cosmological parameters (Ωm and H0) and find that the distribution significantly deviates from isotropy. A local matter underdensity region exists toward (308.4°−48.7+47.6, −18.2°−28.8+21.1) as well as a preferred direction of the cosmic anisotropy (313.4°−18.2+19.6, −16.8°−10.7+11.1) in galactic coordinates. Similar directions may imply that local matter density might be responsible for the anisotropy of the accelerated expansion of the Universe. Results of statistical isotropy analyses including Isotropy and Isotropy with real-data positions (RP) show high confidence levels. For the local matter underdensity, the statistical significances are 2.78σ (isotropy) and 2.34σ (isotropy RP). For the cosmic anisotropy, the statistical significances are 3.96σ (isotropy) and 3.15σ (isotropy RP). The comparison of these two kinds of statistical isotropy analyses suggests that inhomogeneous spatial distribution of real sample can increase the deviation from isotropy. The similar results and findings are also found from reanalyses of the low-redshift sample (lp+) and the lower screening angle (θmax = 60°), but with a slight decrease in statistical significance. Overall, our results provide clear indications for a possible cosmic anisotropy. This possibility must be taken seriously. Further testing is needed to better understand this signal.

Influence of Jets on [O iii] Extensions in Green Pea/Bean Galaxies

We present a study investigating the influence of jets on galaxies exhibiting strong [O iii]λ5007 emission, known as Green Peas and Green Beans. Our sample comprised 12 nearby sources (z ∼ 0.04–0.1, six with jets and six without jets) with high [O iii] luminosity (L ∼ 1040 erg s−1), selected from a radio-selected galaxy sample observed with the Sloan Digital Sky Survey and Radio Sky at Twenty-centimeters survey. We perform Large Binocular Telescope–Multi-Object Double Spectrograph long-slit spectroscopy at two position angles for each galaxy: one aligned with the jet direction and another perpendicular to it. By tracing the [O iii] emission along these slits, we aimed to assess the extension of the narrow line region and examine the impact of jets. Surprisingly, our analysis revealed no preferred direction for the extension of the [O iii] emission, indicating that jets have a limited influence on the extended emission line regions (EELRs). This also suggests the possibility of missed detection of conical-shaped EELRs aligned with the jets, attributable to our slit orientations. Furthermore, we compared the extension of [O ii] emission, which traces star-forming regions, with that of [O iii]. We observed a significant difference, with [O ii] exhibiting a considerably greater extension along the galactic plane. This suggests a stronger association of [O ii] emission with stellar processes.

Analysis of Karst Surface Anisotropy Using Directional Semivariograms, Slovenia

AbstractThe paper presents a study of the anisotropic properties of the karst surface through the use of semivariograms. Karst is formed by hydrogeological and tectonic deformations that determine the surface and subsurface characteristics of the area. Among the most prominent surface features are dolines, which generally form in a linear direction. Semivariograms can be used to determine both the preferred direction of anisotropy and the degree of anisotropy. The surface exhibits the greatest elevation variability in the direction of the most diverse terrain, corresponding to dolines. The results, based on the eight karst areas studied, show that it is possible to detect and, more importantly, quantify anisotropy in all karst areas, although in some cases it is impossible or difficult to detect visually. The directions of the semivariograms agree very well with those obtained from the visual inspection of the maps, as well as with the orientations of the main faults. The method is therefore very useful for quantitative determination of anisotropy and its interpretation could be greatly improved by using the detailed structural geological maps of the karst.

Effect of Manganese Doping in SnO2 Thin Films and its NO2 Gas Sensing Performance

By using an automated nebulizer spray pyrolysis technique with varied concentrations of manganese chloride (0 - 3%) in the spray solution of tin chloride, thin films of pure and manganese-doped tin oxides (Mn-SnO2) were deposited. X-ray diffraction investigations indicated that 2% Manganese chloride concentration in the spray solution promoted development along (200) and (220) directions. The preferred growth direction in the (200) and (220) planes decreased with increasing manganese chloride doping concentration (2-3%) in the solution. The surface morphology of the films had changed as a result of adding Manganese as a dopant. Compositional analysis was carried out using EDAX. From UV-Vis spectroscopy, the optical properties of the SnO2 and Mn-SnO2 thin film were observed; the maximum optical absorbance was in the wavelength range of 300 - 400 nm. The concentration of Mn in the films affected the intensity of the photoluminescence emission peak detected at 347 and 392 nm for pure SnO2 and Mn-SnO2 films, respectively. The gas sensing performance of the films was examined by dynamic method against NO2 gas, at an operating temperature of 250 °C and 400 ppm gas concentration. Mn-SnO2 films achieved quick response and recovery times of 17 s and 34 s.

Insights into the stable preferred growth direction of rods in the colony of Al2O3/ZrO2 (Y2O3) eutectics

The Al2O3/ZrO2 (Y2O3) eutectics were prepared by the melt-grown and seeding melt-grown methods, two non-directional solidification methods. We identify the three-dimensional morphology and crystallographic orientations of the Al2O3/ZrO2 (Y2O3) eutectics using the focused ion beam milling with electron backscattered diffraction and the transmission electron microscopy. The results show that in the colony, there are three parts of the ZrO2 (Y2O3) phase composed of interconnected three-level rods. The crystallographic orientation of the colony axis is variable, but the growth directions of the rods show a commonality, <2̅ 0 2 1>A, in the Al2O3/ ZrO2 (Y2O3) eutectics, which has been also clarified by the interface structure analysis. The analysis of the preferred growth orientation not only enlightens the growth mechanism of Al2O3/ZrO2 (Y2O3) eutectics but also provides a method for the design of novel eutectics.

Phase-field simulation for anisotropic dendrite growth in Mg-3wt.%Zn alloy

The anisotropy interfacial energy changes the growth tendency of dendrites in different directions during solidification, when the growth tendency in a specific direction appears or disappears, the transition of dendrite orientation will happen. In this study, three-dimensional simulations of anisotropic α‐Mg dendrite were conducted by changing the anisotropic interface energy in the phase field model. The variation in the preferred growth direction of equiaxed dendrite in α‐Mg was analyzed by controlling the anisotropic function of the interfaces. The changes in the growth direction of dendrites on different dendrite planes and the distribution of solute were investigated. The dendrites of α‐Mg equiaxed crystals mainly grow in ⟨112‾0⟩ and ⟨112‾3⟩ directions, and the transition of dendrite orientation depends on ⟨112‾0⟩ direction. When ⟨112‾0⟩ direction branching disappears, α‐Mg dendrite is transformed from 18 branches to 12 branches. The solute distribution at the front of the dendrite boundary changes significantly with the growth trend. Differences in the degree of solute distribution affect the solid-liquid interface and change the microstructure of the material.

Constitutive relations for anisotropic porous solids undergoing small strains whose material moduli depend on the density and the pressure

Recently, Arumugam et al. (2023) developed a constitutive relation for the response of isotropic inhomogeneous compressible elastic solids in order to describe the response of the trabecular bone. Since porous solids such as bones, cement concrete, rocks, metallic alloys, etc., are anisotropic, in this short note we develop a constitutive relation for such bodies that exhibit transverse isotropy and also having two preferred directions of symmetry. Another characteristic of bones is that they exhibit different response characteristics in tension and compression, and hence any constitutive relation that is developed has to be capable of describing this. Also, the material moduli depend on both the density and the mean value of the stress (mechanical pressure), as is to be expected in a porous solid. In the constitutive relation that is developed in this paper, though the stress and the linearized strain appear linearly in the constitutive relation, the relationship is nonlinear. We also derive the response of such solids when undergoing uniaxial extension and compression, simple shear and torsion.

Is it possible to speak about the two-dimensional nature of the dielectric properties of layered perovskite-like compounds of the family of Aurivillius–Smolensky phases?

Two-dimensionality of the properties of a volumetric object may be defined by its anisotropy. Perovskite-like compounds of the family of Aurivillius–Smolensky phases (ASPs) have exactly this property. By studying perovskite-like compounds of the family of Aurivillius–Smolensky phases and the changes in the volume of the crystal lattice, occurring in them, namely the increase or decrease in the phase transition temperature (Curie temperature), the preferred direction of grain growth with an increase in the sintering temperature and, as a consequence, the increase in the relative permittivity, the main factor in all cases is the change in the linear parameters a and b, lying in the plane perpendicular to the c-axis.

Propagating population activity patterns during spontaneous slow waves in the thalamus of rodents

Slow waves (SWs) represent the most prominent electrophysiological events in the thalamocortical system under anesthesia and during deep sleep. Recent studies have revealed that SWs have complex spatiotemporal dynamics and propagate across neocortical regions. However, it is still unclear whether neuronal activity in the thalamus exhibits similar propagation properties during SWs. Here, we report propagating population activity in the thalamus of ketamine/xylazine-anesthetized rats and mice visualized by high-density silicon probe recordings. In both rodent species, propagation of spontaneous thalamic activity during up-states was most frequently observed in dorsal thalamic nuclei such as the higher order posterior (Po), lateral posterior (LP) or laterodorsal (LD) nuclei. The preferred direction of thalamic activity spreading was along the dorsoventral axis, with over half of the up-states exhibiting a gradual propagation in the ventral-to-dorsal direction. Furthermore, simultaneous neocortical and thalamic recordings collected under anesthesia demonstrated that there is a weak but noticeable interrelation between propagation patterns observed during cortical up-states and those displayed by thalamic population activity. In addition, using chronically implanted silicon probes, we detected propagating activity patterns in the thalamus of naturally sleeping rats during slow-wave sleep. However, in comparison to propagating up-states observed under anesthesia, these propagating patterns were characterized by a reduced rate of occurrence and a faster propagation speed. Our findings suggest that the propagation of spontaneous population activity is an intrinsic property of the thalamocortical network during synchronized brain states such as deep sleep or anesthesia. Additionally, our data implies that the neocortex may have partial control over the formation of propagation patterns within the dorsal thalamus under anesthesia.

In-car speech enhancement based on source separation technique

This work addresses the solution of localizing and enhancing hands-free speech inside the car environment. Cars have different types of sounds from outside, co-passengers dialogue and noise. To provide better-quality speech, a microphone array-based beamforming technique is used. This research work proposes the method for selected source localization, source separation, and enhancement. An estimation of the direction of arrival (DOA) to localize the signal direction and preferred direction is selected for speech enhancement. The spiral and sine-cosine algorithm (SSCA) algorithm is combined with an adaptive least mean square to adapt the system for different environments. The algorithm is implemented in hardware and tested in a real-time car environment. The results showed significant improvement in signal-to-noise ratio (SNR) of 5.2 dB and perceptual evaluation of speech quality (PESQ) of 2.3. Finally, the model is fine-tuned for the car to get better quality. The proposed technique is efficient, and results are compared with existing methods.

Vapor-to-glass preparation of biaxially aligned organic semiconductors.

Physical vapor deposition (PVD) provides a route to prepare highly stable and anisotropic organic glasses that are utilized in multi-layer structures such as organic light-emitting devices. While previous work has demonstrated that anisotropic glasses with uniaxial symmetry can be prepared by PVD, here, we prepare biaxially aligned glasses in which molecular orientation has a preferred in-plane direction. With the collective effect of the surface equilibration mechanism and template growth on an aligned substrate, macroscopic biaxial alignment is achieved in depositions as much as 180K below the clearing point TLC-iso (and 50K below the glass transition temperature Tg) with single-component disk-like (phenanthroperylene ester) and rod-like (itraconazole) mesogens. The preparation of biaxially aligned organic semiconductors adds a new dimension of structural control for vapor-deposited glasses and may enable polarized emission and in-plane control of charge mobility.

Sustainable synthesis of nano CuO from electronic waste (E-waste) cable: Evaluation of crystallite size via Scherrer equation, Williamson-Hall plot, Halder- Wagner model, Monshi-Scherrer model, size-strain plot

Electronic waste (E-waste) is going to be one of the most hazardous materials for a sustainable environment in the technologically advanced era. In this research, waste electric cable was taken for efficient production of CuO using an easy and simple way. The synthesized product, CuO, was confirmed by the X-ray diffraction (XRD) data, and optical bandgap energy was also estimated. Various crystallographic parameters such as lattice parameters, the volume of unit cell, relative intensity, and preference growth were estimated from XRD data. Scherrer equation, Williamson-Hall plot (Uniform Deformation Model (UDM), Uniform Stress Deformation Model (USDM), Uniform Deformation Energy Density Model (UDEDM)), Halder-Wagner Model, Monshi-Scherrer Model, and Size- Strain plot were employed to calculate crystallite size and few models also exerted stress, strain and energy density. The estimated range of crystallite size was from 7 to 14 nm, strain from 5 × 10−4 to 1.5 × 10−3, stress of 1.0487 GPa, and energy density of 8.12 × 10−4 GPa using different model equations. The preference growth indicated that the (2 0 0) plane is the preferred direction for the synthesized conditions. FTIR spectrum and optical bandgap energy were also estimated for the synthesized products. The Rietveld refinement indicated that the synthesized product contained 99.524 % tenorite (CuO), and 0.476 % Cu2O phases.

Backward fast electrons supported by ionization wave passing through the grid cathode

In this paper, the effect of appearance of fast electrons behind the grid cathode in the direction reverse to the anode is studied computationally. Fast electrons are observed within 0.5 ns after application of a short voltage pulse. The results obtained confirm the possibility of generation of backward fast electrons (some of them are in a runaway mode) and explain the main trends of this process. It is shown that backward fast electrons are supported by the ionization wave (IW). The IW evolution proceeds via two phases. During the first phase, first fast electrons are observed moving toward the anode. Then, multiple individual IWs starting from each individual cathode wire are formed in the anode–cathode gap. The duration of this stage is 0.3 ns and corresponds to the pulse rise time. At the second phase, the separate individual IWs merge in a single flat ionization wave. The IW penetrates through the cathode wires and propagates in the direction reverse to the anode. The preferred direction of fast electrons propagation also reverses. Now, the trajectories of fast electrons are mainly directed away from the anode. The duration of the recorded flux of fast electrons is of the order of a few picoseconds. This time interval correlates with the available experimental data.

Boundary management preferences from a gender and cross-cultural perspective

Although work is increasingly globalized and mediated by technology, little research has accumulated on the role of culture in shaping individuals' preferences regarding the segmentation or integration of their work and family roles. This study examines the relationships between gender egalitarianism (the extent a culture has a fluid understanding of gender roles and promotes gender equality), gender, and boundary management preferences across 27 countries/territories. Based on a sample of 9362 employees, we found that the pattern of the relationship between gender egalitarianism and boundary management depends on the direction of segmentation preferences. Individuals from more gender egalitarian societies reported lower preferences to segment family-from-work (i.e., protect the work role from the family role); however, gender egalitarianism was not directly associated with preferences to segment work-from-family. Moreover, gender was associated with both boundary management directions such that women preferred to segment family-from-work and work-from-family more so than did men. As theorized, we found gender egalitarianism moderated the relationship between gender and segmentation preferences such that women's desire to protect family from work was stronger in lower (vs. higher) gender egalitarianism cultures. Contrary to expectations, women reported a greater preference to protect work from family than men regardless of gender egalitarianism. Implications for boundary management theory and the cross-national work-family literature are discussed.

Characterizing the Directionality of Gravitational Wave Emission from Matter Motions within Core-collapse Supernovae

We analyze the directional dependence of the gravitational wave (GW) emission from 15 3D neutrino radiation hydrodynamic simulations of core-collapse supernovae (CCSNe). Using spin weighted spherical harmonics, we develop a new analytic technique to quantify the evolution of the distribution of GW emission over all angles. We construct a physics-informed toy model that can be used to approximate GW distributions for general ellipsoid-like systems, and use it to provide closed form expressions for the distribution of GWs for different CCSN phases. Using these toy models, we approximate the protoneutron star (PNS) dynamics during multiple CCSN stages and obtain similar GW distributions to simulation outputs. When considering all viewing angles, we apply this new technique to quantify the evolution of preferred directions of GW emission. For nonrotating cases, this dominant viewing angle drifts isotropically throughout the supernova, set by the dynamical timescale of the PNS. For rotating cases, during core bounce and the following tens of milliseconds, the strongest GW signal is observed along the equator. During the accretion phase, comparable—if not stronger—GW amplitudes are generated along the axis of rotation, which can be enhanced by the low T/∣W∣ instability. We show two dominant factors influencing the directionality of GW emission are the degree of initial rotation and explosion morphology. Lastly, looking forward, we note the sensitive interplay between GW detector site and supernova orientation, along with its effect on detecting individual polarization modes.