Stripe order enhanced superconductivity in the Hubbard model.

Unidirectional ("stripe") charge density wave order has now been established as a ubiquitous feature in the phase diagram of the cuprate high-temperature superconductors, where it generally competes with superconductivity. Nonetheless, on theoretical grounds it has been conjectured that stripe order (or other forms of "optimal" inhomogeneity) may play an essential positive role in the mechanism of high-temperature superconductivity. Here, we report density matrix renormalization group studies of the Hubbard model on long four- and six-leg cylinders, where the hopping matrix elements transverse to the long direction are periodically modulated-mimicking the effect of putative period 2 stripe order. We find that even modest amplitude modulations can enhance the long-distance superconducting correlations by many orders of magnitude and drive the system into a phase with a substantial spin gap and superconducting quasi-long-range order with a Luttinger exponent, [Formula: see text].

Coherent emission from surface Josephson plasmons in striped cuprates.

The interplay between charge order and superconductivity remains one of the central themes of research in quantum materials. In the case of cuprates, the coupling between striped charge fluctuations and local electromagnetic fields is especially important, as it affects transport properties, coherence, and dimensionality of superconducting correlations. Here, we study the emission of coherent terahertz radiation in single-layer cuprates of the La2-xBaxCuO4 family, for which this effect is expected to be forbidden by symmetry. We find that emission vanishes for compounds in which the stripes are quasi-static but is activated when c-axis inversion symmetry is broken by incommensurate or fluctuating charge stripes, such as in La1.905Ba0.095CuO4 and in La1.845Ba0.155CuO4. In this case, terahertz radiation is emitted by surface Josephson plasmons, which are generally dark modes, but couple to free space electromagnetic radiation because of the stripe modulation.

Hydrogen-Driven Low-Temperature Topotactic Transition in Nanocomb Cobaltite for Ultralow Power Ionic-Magnetic Coupled Applications.

We reversibly control ferromagnetic-antiferromagnetic ordering in an insulating ground state by annealing tensile-strained LaCoO3 films in hydrogen. This ionic-magnetic coupling occurs due to the hydrogen-driven topotactic transition between perovskite LaCoO3 and brownmillerite La2Co2O5 at a lower temperature (125-200 °C) and within a shorter time (3-10 min) than the oxygen-driven effect (500 °C, tens of hours). The X-ray and optical spectroscopic analyses reveal that the transition results from hydrogen-driven filling of correlated electrons in the Co 3d-orbitals, which successively releases oxygen by destabilizing the CoO6 octahedra into CoO4 tetrahedra. The transition is accelerated by surface exchange, diffusion of hydrogen in and oxygen out through atomically ordered oxygen vacancy "nanocomb" stripes in the tensile-strained LaCoO3 films. Our ionic-magnetic coupling with fast operation, good reproducibility, and long-term stability is a proof-of-principle demonstration of high-performance ultralow power magnetic switching devices for sensors, energy, and artificial intelligence applications, which are keys for attaining carbon neutrality.

Adsorption on a Spherical Colloidal Particle from a Mixture of Nanoparticles with Competing Interactions.

Adsorption of nanoparticles on a spherical colloidal particle is studied by molecular dynamics simulations. We consider a generic model for a mixture of nanoparticles with energetically favored self-assembly into alternating layers of the two components. When both components are attracted to the colloidal particle, the adsorbed nanoparticles self-assemble either into alternating parallel tori and clusters at the two poles of the colloidal particle, or into alternating spirals wrapped around the spherical surface. The long-lived metastable states obtained in simulations follow from the spherical shape of the adsorbing surface and the requirement that the neighboring chains of the nanoparticles are composed of different components. A geometrical construction leading to all such patterns is presented. When the second component particles are repelled from the colloidal particle and the attraction of the first component is strong, the attracted particles form a monolayer at the surface of the colloidal particle that screens the repulsion of the second component. The subsequent adsorbed alternating spherical layers of the two components form together a thick shell. This structure leads to the adsorption that is larger than in the case of the same attraction of the two components to the colloidal particle.

Lattice Model Results for Pattern Formation in a Mixture with Competing Interactions.

A monolayer consisting of two types of particles, with energetically favored alternating stripes of the two components, is studied by Monte Carlo simulations and within a mesoscopic theory. We consider a triangular lattice model and assume short-range attraction and long-range repulsion between particles of the same kind, as well as short-range repulsion and long-range attraction for the cross-interaction. The structural evolution of the model upon increasing temperature is studied for equal chemical potentials of the two species. We determine the structure factor, the chemical potential-density isotherms, the specific heat, and the compressibility, and show how these thermodynamic functions are associated with the spontaneous formation of stripes with varying degrees of order.

Pathogenesis of wild-type- and vaccine-based recombinant peste des petits ruminants virus (PPRV) expressing EGFP in experimentally infected domestic goats.

Peste des petits ruminants virus (PPRV) is a highly contagious morbillivirus related to measles and canine distemper virus, mostly affecting small ruminants. The corresponding PPR disease has a high clinical impact in goats and is characterized by fever, oral and nasal erosions, diarrhoea and pneumonia. In addition, massive infection of lymphoid tissues causes lymphopaenia and immune suppression. This results in increased susceptibility to secondary bacterial infections, explaining the observed high mortality in some outbreaks. We studied the pathogenesis of PPR by experimental inoculation of Dutch domestic goats with a recombinant virulent PPRV strain modified to express EGFP and compared it to an EGFP-expressing vaccine strain of PPRV. After intratracheal inoculation with virulent PPRV, animals developed fever, viraemia and leucopaenia, and shed virus from the respiratory and gastro-intestinal tracts. Macroscopic evaluation of fluorescence at the peak of infection 7 days post-inoculation (dpi) showed prominent PPRV infection of the respiratory tract, lymphoid tissues, gastro-intestinal tract, mucosae and skin. Flow cytometry of PBMCs collected over time demonstrated a cell-associated viraemia mediated by infected lymphocytes. At 14 dpi, pathognomonic zebra stripes were detected in the mucosa of the large intestine. In contrast, vaccine strain-inoculated goats remained largely macroscopically fluorescence negative and did not present clinical signs. A low-level viraemia was detected by flow cytometry, but at necropsy no histological lesions were observed. Animals from both groups seroconverted as early as 7 dpi and sera efficiently neutralized virulent PPRV in vitro. Combined, this work presents a study of the pathogenesis of wild type- and vaccine-based PPRV in its natural host. This study shows the strength of recombinant EGFP-expressing viruses in fluorescence-guided pathogenesis studies.

Why don't horseflies land on zebras?

Stripes deter horseflies (tabanids) from landing on zebras and, while several mechanisms have been proposed, these hypotheses have yet to be tested satisfactorily. Here, we investigated three possible visual mechanisms that could impede successful tabanid landings (aliasing, contrast and polarization) but additionally explored pattern element size employing video footage of horseflies around differently patterned coats placed on domestic horses. We found that horseflies are averse to landing on highly but not on lightly contrasting stripes printed on horse coats. We could find no evidence for horseflies being attracted to coats that better reflected polarized light. Horseflies were somewhat less attracted to regular than to irregular check patterns, but this effect was not large enough to support the hypothesis of disrupting optic flow through aliasing. More likely it is due to attraction towards larger dark patches present in the irregular check patterns, an idea bolstered by comparing landings to the size of dark patterns present on the different coats. Our working hypothesis for the principal anti-parasite features of zebra pelage are that their stripes are sharply outlined and thin because these features specifically eliminate the occurrence of large monochrome dark patches that are highly attractive to horseflies at close distances.

The development of a home-based technology to improve gait in people with Parkinson's disease: a feasibility study.

BACKGROUND: People with Parkinson's disease (PwP) may experience gait impairment and freezing of gait (FOG), a major cause of falls. External cueing, including visual (e.g., spaced lines on the floor) and auditory (e.g., rhythmic metronome beats) stimuli, are considered effective in alleviating mobility deficits and FOG. Currently, there is a need for a technology that delivers automatic, individually adjusted cues in the homes of PwP. The aims of this feasibility study were to describe the first step toward the development of a home-based technology that delivers external cues, test its effect on gait, and assess user experience. METHODS: Iterative system development was performed by our multidisciplinary team. The system was designed to deliver visual and auditory cues: light stripes projected on the floor and metronome beats, separately. Initial testing was performed using the feedback of five healthy elderly individuals on the cues' clarity (clear visibility of the light stripes and the sound of metronome beats) and discomfort experienced. A pilot study was subsequently conducted in the homes of 15 PwP with daily FOG. We measured participants' walking under three conditions: baseline (with no cues), walking with light stripes, and walking to metronome beats. Outcome measures included step length and step time. User experience was also captured in semi-structured interviews. RESULTS: Repeated-measures ANOVA of gait assessment in PwP revealed that light stripes significantly improved step length (p = 0.009) and step time (p = 0.019) of PwP. No significant changes were measured in the metronome condition. PwP reported that both cueing modalities improved their gait, confidence, and stability. Most PwP did not report any discomfort in either modality and expressed a desire to have such a technology in their homes. The metronome was preferred by the majority of participants. CONCLUSIONS: This feasibility study demonstrated the usability and potential effect of a novel cueing technology on gait, and represents an important first step toward the development of a technology aimed to prevent FOG by delivering individually adjusted cues automatically. A further full-scale study is needed. Trial registration This study was registered in ClinicalTrials.gov at 1/2/2022 NCT05211687.

Competing stripe and magnetic phases in the cuprates from first principles.

Realistic description of competing phases in complex quantum materials has proven extremely challenging. For example, much of the existing density-functional-theory-based first-principles framework fails in the cuprate superconductors. Various many-body approaches involve generic model Hamiltonians and do not account for the interplay between the spin, charge, and lattice degrees of freedom. Here, by deploying the recently constructed strongly constrained and appropriately normed (SCAN) density functional, we show how the landscape of competing stripe and magnetic phases can be addressed on a first-principles basis both in the parent insulator YBa2Cu3O6 and the near-optimally doped YBa2Cu3O7 as archetype cuprate compounds. In YBa2Cu3O7, we find many stripe phases that are nearly degenerate with the ground state and may give rise to the pseudogap state from which the high-temperature superconducting state emerges. We invoke no free parameters such as the Hubbard U, which has been the basis of much of the existing cuprate literature. Lattice degrees of freedom are found to be crucially important in stabilizing the various phases.

Hall Effect Anisotropy in the Paramagnetic Phase of Ho0.8Lu0.2B12 Induced by Dynamic Charge Stripes.

A detailed study of charge transport in the paramagnetic phase of the cage-cluster dodecaboride Ho0.8Lu0.2B12 with an instability both of the fcc lattice (cooperative Jahn−Teller effect) and the electronic structure (dynamic charge stripes) was carried out at temperatures 1.9−300 K in magnetic fields up to 80 kOe. Four mono-domain single crystals of Ho0.8Lu0.2B12 samples with different crystal axis orientation were investigated in order to establish the singularities of Hall effect, which develop due to (i) the electronic phase separation (stripes) and (ii) formation of the disordered cage-glass state below T*~60 K. It was demonstrated that a considerable intrinsic anisotropic positive component ρanxy appears at low temperatures in addition to the ordinary negative Hall resistivity contribution in magnetic fields above 40 kOe applied along the [001] and [110] axes. A relation between anomalous components of the resistivity tensor ρanxy~ρanxx1.7 was found for H||[001] below T*~60 K, and a power law ρanxy~ρanxx0.83 for the orientation H||[110] at temperatures T < TS~15 K. It is argued that below characteristic temperature TS~15 K the anomalous odd ρanxy(T) and even ρanxx(T) parts of the resistivity tensor may be interpreted in terms of formation of long chains in the filamentary structure of fluctuating charges (stripes). We assume that these ρanxy(H||[001]) and ρanxy(H||[110]) components represent the intrinsic (Berry phase contribution) and extrinsic (skew scattering) mechanism, respectively. Apart from them, an additional ferromagnetic contribution to both isotropic and anisotropic components in the Hall signal was registered and attributed to the effect of magnetic polarization of 5d states (ferromagnetic nano-domains) in the conduction band of Ho0.8Lu0.2B12.

Critical factors in achieving fine-scale functional MRI: Removing sources of inadvertent spatial smoothing.

Ultra-high Field (≥7T) functional magnetic resonance imaging (UHF-fMRI) provides opportunities to resolve fine-scale features of functional architecture such as cerebral cortical columns and layers, in vivo. While the nominal resolution of modern fMRI acquisitions may appear to be sufficient to resolve these features, several common data preprocessing steps can introduce unwanted spatial blurring, especially those that require interpolation of the data. These resolution losses can impede the detection of the fine-scale features of interest. To examine quantitatively and systematically the sources of spatial resolution losses occurring during preprocessing, we used synthetic fMRI data and real fMRI data from the human visual cortex-the spatially interdigitated human V2 "thin" and "thick" stripes. The pattern of these cortical columns lies along the cortical surface and thus can be best appreciated using surface-based fMRI analysis. We used this as a testbed for evaluating strategies that can reduce spatial blurring of fMRI data. Our results show that resolution losses can be mitigated at multiple points in preprocessing pathway. We show that unwanted blur is introduced at each step of volume transformation and surface projection, and can be ameliorated by replacing multi-step transformations with equivalent single-step transformations. Surprisingly, the simple approaches of volume upsampling and of cortical mesh refinement also helped to reduce resolution losses caused by interpolation. Volume upsampling also serves to improve motion estimation accuracy, which helps to reduce blur. Moreover, we demonstrate that the level of spatial blurring is nonuniform over the brain-knowledge which is critical for interpreting data in high-resolution fMRI studies. Importantly, our study provides recommendations for reducing unwanted blurring during preprocessing as well as methods that enable quantitative comparisons between preprocessing strategies. These findings highlight several underappreciated sources of a spatial blur. Individually, the factors that contribute to spatial blur may appear to be minor, but in combination, the cumulative effects can hinder the interpretation of fine-scale fMRI and the detectability of these fine-scale features of functional architecture.

Long anterior lens zonules with retinal stripes: a case report.

BACKGROUND: Long anterior lens zonules (LAZs) is a rare disease that was mostly conducted among African Americans. Through the observation of a Chinese patient, we discoverd that the disease may show different characteristics in Asians. CASE PRESENTATION: A patient with vision loss due to a macular hole was found to have several special clinical signs during vitrectomy combined with phacoemulsification and intraocular lens implantation surgery in our hospital, including radially oriented lines on the anterior capsule with pigment, a shallow anterior chamber, slightly high intraocular pressure, and radial retinal stripes in the peripheral retina. Finally, he was diagnosed with long anterior lens zonule syndrome. CONCLUSION: Clinicians need to pay more attention to the rare disease LAZs. It is important to tear the appropriate size of the anterior capsule so as to avoid radial capsular tearing and intraocular lens dislocation.

["Lines and stripes" in chest x-ray]. / "Lines und stripes" in der Thorax-Übersichtsaufnahme.

CLINICAL ISSUE: Chest x­ray is a projection technique which reduces a three-dimensional body to a two-dimensional image. Inevitably, this leads to loss of information. Hence, it is much more difficult to determine anatomy and pathology in chest ray than in computed tomography. PERFORMANCE: The so-called "lines and stripes" are prominent landmarks. Knowledge of these lines and stripes eases interpretation of chest x­rays. ACHIEVEMENTS: This review describes anatomy and normal morphology of all relevant lines and stripes and gives differential diagnoses in case of pathologic morphology.

Of bars and stripes: A Malawi cichlid hybrid cross provides insights into genetic modularity and evolution of modifier loci underlying colour pattern diversification.

Understanding the origins of phenotypic diversity among closely related species remains an important largely unsolved question in evolutionary biology. With over 800 species, Lake Malawi haplochromine cichlid fishes are a prominent example of extremely fast evolution of diversity including variation in colouration. Previously, a single major effect gene, agrp2 (asip2b), has been linked to evolutionary losses and gains of horizontal stripe patterns in cichlids, but it remains unknown what causes more fine-scale variation in the number and continuity of the stripes. Also, the genetic basis of the most common colour pattern in African cichlids, vertical bars, and potential interactions between the two colour patterns remain unknown. Based on a hybrid cross of the horizontally striped Lake Malawi cichlid Pseudotropheus cyaneorhabdos and the vertically barred species Chindongo demasoni we investigated the genetic basis of both colour patterns. The distribution of phenotypes in the F2  generation of the cross indicates that horizontal stripes and vertical bars are independently inherited patterns that are caused by two sets of genetic modules. While horizontal stripes are largely controlled by few major effect loci, vertical bars are a highly polygenic trait. Horizontal stripes show substantial variation in the F2  generation that, interestingly, resemble naturally occurring phenotypes found in other Lake Malawi cichlid species. Quantitative trait loci (QTL) mapping of this cross reveals known (agrp2) and unknown loci underlying horizontal stripe patterns. These findings provide novel insights into the incremental fine-tuning of an adaptive trait that diversified through the evolution of additional modifier loci.

Helmholtz Versus Haute Couture: How Horizontal Stripes and Dark Clothes Make You Look Thinner.

In Helmholtz's illusion, a square with horizontal stripes appears taller than an identical square with vertical stripes. This effect has also been observed in experiments with human stimuli, where a human figure wearing a dress with horizontal stripes appears thinner than a drawing clad in vertical stripes. These findings do not agree with the common belief that clothes with horizontal stripes make someone appear wider, neither do they disentangle whether the horizontal or vertical stripes account for the thinning effect. In the present study, we focused on the effect of horizontal stripes in clothes comparing horizontal stripes against no-stripes (not against vertical; Experiments 1 and 2), using photos of a real-life female model, and controlling for the average luminance of the stripes (Experiment 2). Results showed that horizontal stripes and lower luminance have-independently-a small-to-moderate thinning effect on the perceived size of the body, and the effect is larger when the two variables are combined. In Experiment 3, we further show that the thinning effect due to the luminance of the dress is enhanced when the general background gets darker.

Zebra stripes, tabanid biting flies and the aperture effect.

Of all hypotheses advanced for why zebras have stripes, avoidance of biting fly attack receives by far the most support, yet the mechanisms by which stripes thwart landings are not yet understood. A logical and popular hypothesis is that stripes interfere with optic flow patterns needed by flying insects to execute controlled landings. This could occur through disrupting the radial symmetry of optic flow via the aperture effect (i.e. generation of false motion cues by straight edges), or through spatio-temporal aliasing (i.e. misregistration of repeated features) of evenly spaced stripes. By recording and reconstructing tabanid fly behaviour around horses wearing differently patterned rugs, we could tease out these hypotheses using realistic target stimuli. We found that flies avoided landing on, flew faster near, and did not approach as close to striped and checked rugs compared to grey. Our observations that flies avoided checked patterns in a similar way to stripes refutes the hypothesis that stripes disrupt optic flow via the aperture effect, which critically demands parallel striped patterns. Our data narrow the menu of fly-equid visual interactions that form the basis for the extraordinary colouration of zebras.

Contrasting stripes are a widespread feature of group living in birds, mammals and fishes.

Grouping is a widespread form of predator defence, with individuals in groups often performing evasive collective movements in response to attack by predators. Individuals in these groups use behavioural rules to coordinate their movements, with visual cues about neighbours' positions and orientations often informing movement decisions. Although the exact visual cues individuals use to coordinate their movements with neighbours have not yet been decoded, some studies have suggested that stripes, lines, or other body patterns may act as conspicuous conveyors of movement information that could promote coordinated group movement, or promote dazzle camouflage, thereby confusing predators. We used phylogenetic logistic regressions to test whether the contrasting achromatic stripes present in four different taxa vulnerable to predation, including species within two orders of birds (Anseriformes and Charadriiformes), a suborder of Artiodactyla (the ruminants), and several orders of marine fishes (predominantly Perciformes) were associated with group living. Contrasting patterns were significantly more prevalent in social species, and tended to be absent in solitary species or species less vulnerable to predation. We suggest that stripes taking the form of light-coloured lines on dark backgrounds, or vice versa, provide a widespread mechanism across taxa that either serves to inform conspecifics of neighbours' movements, or to confuse predators, when moving in groups. Because detection and processing of patterns and of motion in the visual channel is essentially colour-blind, diverse animal taxa with widely different vision systems (including mono-, di-, tri-, and tetrachromats) appear to have converged on a similar use of achromatic patterns, as would be expected given signal-detection theory. This hypothesis would explain the convergent evolution of conspicuous achromatic patterns as an antipredator mechanism in numerous vertebrate species.

High-temperature charge density wave correlations in La1.875Ba0.125CuO4 without spin-charge locking.

Although all superconducting cuprates display charge-ordering tendencies, their low-temperature properties are distinct, impeding efforts to understand the phenomena within a single conceptual framework. While some systems exhibit stripes of charge and spin, with a locked periodicity, others host charge density waves (CDWs) without any obviously related spin order. Here we use resonant inelastic X-ray scattering to follow the evolution of charge correlations in the canonical stripe-ordered cuprate La1.875Ba0.125CuO4 across its ordering transition. We find that high-temperature charge correlations are unlocked from the wavevector of the spin correlations, signaling analogies to CDW phases in various other cuprates. This indicates that stripe order at low temperatures is stabilized by the coupling of otherwise independent charge and spin density waves, with important implications for the relation between charge and spin correlations in the cuprates.

Spatial structure of neuronal receptive field in awake monkey secondary visual cortex (V2).

Visual processing depends critically on the receptive field (RF) properties of visual neurons. However, comprehensive characterization of RFs beyond the primary visual cortex (V1) remains a challenge. Here we report fine RF structures in secondary visual cortex (V2) of awake macaque monkeys, identified through a projection pursuit regression analysis of neuronal responses to natural images. We found that V2 RFs could be broadly classified as V1-like (typical Gabor-shaped subunits), ultralong (subunits with high aspect ratios), or complex-shaped (subunits with multiple oriented components). Furthermore, single-unit recordings from functional domains identified by intrinsic optical imaging showed that neurons with ultralong RFs were primarily localized within pale stripes, whereas neurons with complex-shaped RFs were more concentrated in thin stripes. Thus, by combining single-unit recording with optical imaging and a computational approach, we identified RF subunits underlying spatial feature selectivity of V2 neurons and demonstrated the functional organization of these RF properties.

The Ferdinando Rossi Memorial Lecture: Zones and Stripes-Pattern Formation in the Cerebellum.

The cerebellum has a complex architecture-highly reproducible and conserved through evolution. Cerebellar architecture is organized around the Purkinje cell. Purkinje cells in the mouse cerebellum come in many different subtypes, identifiable by expression markers, sensitivity to mutation, etc. These are organized first into five "transverse zones," each of which is further subdivided into dozens of reproducible "stripes." This arrangement serves as the scaffolding to organize afferent topography and restrict the distribution of excitatory and inhibitory interneurons. This brief review will survey some of the mechanisms that lead to the formation of this elaborate pattern during cerebellar development. Pattern formation in the cerebellar cortex is a multistage process that begins early in development with the generation of the various Purkinje cell subtypes, and matures through the dispersal of Purkinje cell clusters into stripes. Two developmental processes will be discussed in particular: the mechanisms that lead to Purkinje cell subtype specification (i.e., how different kinds of Purkinje cells are made) and the role played by Purkinje cell migration in pattern formation (i.e., how these Purkinje cell subtypes end up in a reproducible array of stripes).