bluuebunny/crossref_metadata_2025 huggingface dataset:
A systematic review and meta-analysis of tau phosphorylation in mouse models of familial Alzheimer’s disease
Authors: Kourti Malamati , Metaxas Athanasios
Published: October 2023

Background

Transgenic models of familial Alzheimer’s disease (AD) serve as valuable tools for probing the molecular mechanisms associated with amyloid-beta (Aβ)-induced pathology. Here, we sought to evaluate the levels of phosphorylated tau (p-tau) protein, and explore potential age-related variations in the hyperphosphorylation of tau, in mouse models of cerebral amyloidosis.

Methods

The PubMed and Scopus databases were searched for studies measuring soluble p-tau in 5xFAD,APPswe/PSEN1de9, J20 and APP23 mice. Data were extracted and analyzed using standardized procedures.

Results

For the 5xFAD model, the search yielded 36 studies eligible for meta-analysis. Levels of p-tau were higher in 5xFAD mice relative to control, a difference that was evident in both the carboxy-terminal (CT) and proline-rich (PR) domains of tau. Age negatively moderated the effects of genotype on CT domain phosphorylated tau, particularly in studies using hybrid mice, female mice, and preparations from the cortex. For theAPPswe/PSEN1de9model, the search yielded 27 studies. Analysis showed tau hyperphosphorylation in transgenic vs. control animals, evident in both the CT and PR regions of tau. Age positively moderated the effects of genotype on PR domain phosphorylated tau in the cortex ofAPPswe/PSEN1de9mice. A meta-analysis was not performed for the J20 and APP23 models, due to the limited number of studies measuring p-tau levels in these mice (<10 studies).

Conclusions

Although tau is hyperphosphorylated in both 5xFAD andAPPswe/PSEN1de9mice, the effects of ageing on p-tau are contingent upon the mouse model being examined. These observations emphasize the importance of tailoring model selection to the appropriate disease stage when assessing the relationship between Aβ and tau, and suggest that there are optimal intervention points for the administration of both anti-amyloid and anti-tau therapies.
Regulation of pupil size in natural vision across the human lifespan
Authors: Lazar Rafael , Degen Josefine , Fiechter Ann-Sophie , Monticelli Aurora , Spitschan Manuel
Published: October 2023

Vision is mediated by light passing through the aperture of the eye, the pupil, which changes in diameter from ~2 to ~8 mm from the brightest to the darkest illumination. In addition, with age, mean pupil size declines. In laboratory experiments, factors affecting pupil size can be experimentally controlled or held constant, but how the pupil reflects changes in retinal input from the visual environment under natural viewing conditions is not clear. Here, we address this question in a field experiment (N=83, 43 female, age: 18-87 years) using a custom-made wearable video-based eye tracker with a spectroradiometer measuring spectral irradiance in the approximate corneal plane. Participants moved in and between indoor and outdoor environments varying in spectrum and engaged in a range of everyday tasks. Our real-world data confirm that light-adapted pupil size is determined by light intensity, with clear superiority of melanopic over photopic units, and that it decreases with increasing age, yielding steeper slopes at lower light levels. We find no indication that sex, iris colour or reported caffeine consumption affect pupil size. Taken together, the data provide strong evidence for considering age in personalised lighting solutions and for using melanopsin-weighted light measures to assess real-world lighting conditions.
Fluorescence dynamics of lysosomal-related organelle flashing in the intestinal cells ofCaenorhabditis elegans
Authors: Tan Chieh-Hsiang , Ding Keke , Zhang Mark G. , Sternberg Paul W.
Published: October 2023

The biological roles of the autofluorescent lysosome-related organelles (“gut granules”) in the intestinal cells of many nematodes, includingCaenorhabditis elegans, have been shown to play an important role in metabolic and signaling processes, but they have not been fully characterized. We report here a previously undescribed phenomenon in which the autofluorescence of these granules increased and then decreased in a rapid and dynamic manner that may be associated with nutrient availability. We observed that two distinct types of fluorophores are likely present in the gut granules. One displays a “flashing” phenomenon, in which fluorescence decrease is preceded by a sharp increase in fluorescence intensity that expands into the surrounding area, while the other simply decreases in intensity. Gut granule flashing was observed in the different life stages ofC. elegansand was also observed inSteinernema hermaphroditum, an evolutionarily distant nematode. We hypothesize that the “flashing” fluorophore is pH-sensitive, and the fluorescence intensity change results from the fluorophore being released from the lysosome-related organelles into the relatively higher pH environment of the cytosol. The visually spectacular dynamic fluorescence phenomenon we describe might provide a handle on the biochemistry and genetics of these lysosome-related organelles.
Mating-induced ecdysone in the testis disrupts soma-germline contacts and stem cell cytokinesis
Authors: Roach Tiffany V. , Lenhart Kari F.
Published: October 2023

Germline maintenance relies on adult stem cells to continually replenish lost gametes over a lifetime and respond to external cues altering the demands on the tissue. Mating worsens germline homeostasis over time, yet a negative impact on stem cell behavior has not been explored. Using extended live imaging of theDrosophilatestis stem cell niche, we find that short periods of mating in young males disrupts cytokinesis in germline stem cells (GSCs). This defect leads to failure of abscission, preventing release of differentiating cells from the niche. We find that GSC abscission failure is caused by increased ecdysone hormone signaling induced upon mating, which leads to disrupted somatic encystment of the germline. Abscission failure is rescued by isolating males from females but recurs with resumption of mating. Importantly, reiterative mating also leads to increased GSC loss, requiring increased restoration of stem cells via symmetric renewal and de-differentiation. Together, these results suggest a model whereby acute mating results in hormonal changes that negatively impact GSC cytokinesis but preserves the stem cell population.

Graphical Abstract
Revealing the spatial pattern of brain hemodynamic sensitivity to healthy aging through sparse DCM
Authors: Baron Giorgia , Silvestri Erica , Benozzo Danilo , Chiuso Alessandro , Bertoldo Alessandra
Published: October 2023

Age-related changes in the BOLD response could reflect neuro-vascular coupling modifications rather than simply impairments in neural functioning. In this study, we propose the use of a generative dynamic causal model (DCM) to decouple neuronal and vascular factors in the BOLD signal, with the aim of characterizing the whole-brain spatial pattern of hemodynamic sensitivity to healthy aging, as well as to test the role of hemodynamic features as independent predictors in an age-classification model.In this view, DCM was applied to the resting-state fMRI data of a cohort of 126 healthy individuals in a wide age range, providing reliable estimates of the hemodynamic response function (HRF) for each subject and each region of interest. Then, some features characterizing each HRF curve were extracted and used to fit a multivariate logistic regression model to predict the age class of each individual. Ultimately, we tested the final predictive model on an independent dataset of 338 healthy subjects selected from the Human Connectome Project Aging (HCP-A) and Development (HCP-D) cohorts. Our results entail the spatial heterogeneity of the age effects on the hemodynamic component, since its impact resulted to be strongly region- and population-specific, discouraging any space-invariant corrective procedures that attempt to correct for vascular factors when carrying out functional studies involving groups with different ages. Moreover, we demonstrated that a strong interaction exists between some specific hemodynamic features and age, further supporting the essential role of the hemodynamic factor as independent predictor of biological aging, rather than a simple confounding variable.

Significance statement

By inferring region-wise hemodynamic profiles at the individual level, this is the first study providing an exhaustive whole-brain characterization of the hemodynamic sensitivity to healthy aging, reporting further evidence of the vascular changes across the adult lifespan. Using a predictive framework, we analysed the statistical influence of advancing age on individual regional hemodynamic attributes, offering a quantitative evaluation of the diverse hemodynamic bias across different brain regions. We unveiled a specific set of hemodynamic predictors to discriminate young from elderly people, mainly describing vascular properties of right-hemispheric areas. This suggests the asymmetric nature of vascular degeneration processes affecting the human brain at the latest stage of life, other than a potential biomarker that could be relevant for brain-age prediction.
Human motor unit discharge patterns reveal differences in neuromodulatory and inhibitory drive to motoneurons across contraction levels
Authors: Škarabot Jakob , Beauchamp James A , Pearcey Gregory EP
Published: October 2023

All motor commands converge onto motor units (MUs), which transduce the signals into mechanical actions of muscle fibres. This process is highly non-linear due to combinations of ionotropic (excitatory/inhibitory) and metabotropic (neuromodulatory) inputs. Neuromodulatory inputs facilitate dendritic persistent inward currents, which introduce non-linearities in MU discharge patterns and provide insights into the structure of motor commands. Here, we investigated the relative contribution of neuromodulation and the pattern of inhibition to modulate human MU discharge patterns with contraction forces up to 70% maximum. Leveraging MU discharge patterns identified from three human muscles (tibialis anterior – TA, and vastus lateralis and medialis), we show that with increased contraction force, the onset-offset discharge rate hysteresis (ΔF) increased whilst ascending MU discharge patterns become more linear, with lower slopes. In a follow-up experiment, we demonstrated that the observations of increased ΔF and more linear ascending MU discharge patterns with greater contraction force are maintained even when accounting for contraction duration and rate of force increase. We then reverse-engineered TA MU discharge patterns using highly realistic in silico motoneuron pools to substantiate the inferred physiological mechanisms from human recordings. We demonstrate a sharply restricted solution space, whereby the contraction force-induced changes in experimentally obtained MU discharge patterns can only be recreated with increased neuromodulation and a more reciprocal (i.e. push-pull) inhibitory pattern. In summary, our experimental and computational data suggest that neuromodulation and inhibitory patterns are uniquely shaped to generate discharge patterns that support force increases across a large proportion of the motor pool’s recruitment range.

Significance statement

How the structure of motor commands is modified to scale motor output is largely speculative despite its critical role in the neural control of movement. Here, we demonstrate that human motor unit discharge patterns become more linear and exhibit greater discharge rate hysteresis with greater contraction force. These experimentally observed patterns can only be replicated in silico with biophysical models of spinal motoneurons by increasing neuromodulation and shifting inhibitory commands to be more reciprocal to excitation (i.e., push-pull excitation-inhibition synaptic control). Collectively, these results suggest that the structure of motor commands is uniquely orchestrated to support increases in contraction force.
Neural correlates of crowding in macaque area V4
Authors: Kim Taekjun , Pasupathy Anitha
Published: October 2023

Visual crowding refers to the phenomenon where a target object that is easily identifiable in isolation becomes difficult to recognize when surrounded by other stimuli (distractors). Extensive psychophysical studies support two alternative possibilities for the underlying mechanisms. One hypothesis suggests that crowding results from the loss of visual information due to pooled encoding of multiple nearby stimuli in the mid-level processing stages along the ventral visual pathway. Alternatively, crowding may arise from limited resolution in decoding object information during recognition and the encoded information may remain inaccessible unless it is salient. To rigorously test these alternatives, we studied the responses of single neurons in macaque area V4, an intermediate stage of the ventral, object-processing pathway, to parametrically designed crowded displays and their texture-statistics matched metameric counterparts. Our investigations reveal striking parallels between how crowding parameters, e.g., number, distance, and position of distractors, influence human psychophysical performance and V4 shape selectivity. Importantly, we found that enhancing the salience of a target stimulus could reverse crowding effects even in highly cluttered scenes and such reversals could be protracted reflecting a dynamical process. Overall, we conclude that a pooled encoding of nearby stimuli cannot explain the observed responses and we propose an alternative model where V4 neurons preferentially encode salient stimuli in crowded displays.

Significance Statement

Psychophysicists have long studied the phenomena of visual crowding, but the underlying neural mechanisms are unknown. Our results reveal striking correlations between the responses of neurons in mid-level visual cortical area V4 and psychophysical demonstrations, revealing that crowding is influenced not only by the number and spatial arrangement of distractors but also by the similarity of features between target and distractors, as well as among the distractors themselves. Overall, our studies provide strong evidence that the visual system uses strategies to preferentially encode salient features in a visual scene presumably to process visual information efficiently. When multiple nearby stimuli are equally salient, the phenomenon of crowding ensues.
Accelerated Aging after Traumatic Brain Injury: an ENIGMA Multi-Cohort Mega-Analysis
Authors: Dennis Emily L , Vervoordt Samantha , Adamson Maheen M , Amiri Houshang , Bigler Erin D , Caeyenberghs Karen , Cole James H , Dams-O’Connor Kristen , Deutscher Evelyn M , Dobryakova Ekaterina , Genova Helen M , Grafman Jordan H , Håberg Asta K , Hollstrøm Torgeir , Irimia Andrei , Koliatsos Vassilis E , Lindsey Hannah M , Livny Abigail , Menon David K , Merkley Tricia L , Mohamed Abdalla Z , Mondello Stefania , Monti Martin M , Newcome Virginia FJ , Newsome Mary R , Ponsford Jennie , Rabinowitz Amanda , Smevik Hanne , Spitz Gershon , Vankatesan Umesh M , Westlye Lars T , Zafonte Ross , Thompson Paul M , Wilde Elisabeth A , Olsen Alexander , Hillary Frank G
Published: October 2023

Objective

The long-term consequences of traumatic brain injury (TBI) on brain structure remain uncertain. In light of current evidence that even a single significant brain injury event increases the risk of dementia, brain-age estimation could provide a novel and efficient indexing of the long-term consequences of TBI. Brain-age procedures use predictive modeling to calculate brain-age scores for an individual using MRI data. Complicated mild, moderate and severe TBI (cmsTBI) is associated with a higher predicted (brain) age difference (PAD), but the progression of PAD over time remains unclear. Here we sought to examine whether PAD increases as a function of time since injury (TSI).

Methods

As part of the ENIGMA Adult Moderate and Severe (AMS)-TBI working group, we examine the largest TBI sample to date (n=343), along with controls, for a total sample size of 540, to reproduce and extend prior findings in the study of TBI brain age. T1w-MRI data were aggregated across 7 cohorts and brain age was established using a similar brain age algorithm to prior work in TBI.

Results

Findings show that PAD widens with longer TSI, and there was evidence for differences between sexes in PAD, with men showing more advanced brain age. We did not find evidence supporting a link between PAD and cognitive performance.

Interpretation

This work provides evidence that changes in brain structure after cmsTBI are dynamic, with an initial period of change, followed by relative stability, eventually leading to further changes in the decades after a single cmsTBI.
Mining the Health Disparities and Minority Health Bibliome: A Computational Scoping Review and Gap Analysis of 200,000+ Articles
Authors: Reyes Nieva Harry , Bakken Suzanne , Elhadad Noémie
Published: October 2023

Without comprehensive examination of available literature on health disparities and minority health (HDMH), the field is left vulnerable to disproportionately focus on specific populations or conditions, curtailing our ability to fully advance health equity. Using scalable open-source methods, we conducted a computational scoping review of more than 200,000 articles to investigate major populations, conditions, and themes in the literature as well as notable gaps. We also compared trends in studied conditions to their relative prevalence in the general population using insurance claims (42MM Americans). HDMH publications represent 1% of articles in MEDLINE. Most studies are observational in nature, though randomized trial reporting has increased five-fold in the last twenty years. Half of all HDMH articles concentrate on only three disease groups (cancer, mental health, endocrine/metabolic disorders), while hearing, vision, and skin-related conditions are among the least well represented despite substantial prevalence. To support further investigation, we also present HDMH Monitor, an interactive dashboard and repository generated from the HDMH bibliome.
Investigation of the genetic aetiology of Lewy body diseases with and without dementia
Authors: Wu Lesley , Real Raquel , Martinez Alejandro , Chia Ruth , Lawton Michael A , Shoai Maryam , Bresner Catherine , Hubbard Leon , Blauwendraat Cornelis , Singleton Andrew B , Ryten Mina , Scholz Sonja W. , Traynor Bryan J , Williams Nigel , Hu Michele T M , Ben-Shlomo Yoav , Grosset Donald G , Hardy John , Morris Huw R ,   International LBD Genomic Consortium
Published: October 2023

Up to 80% of Parkinson’s disease patients develop dementia, but time to dementia varies widely from motor symptom onset. Dementia with Lewy bodies presents with clinical features similar to Parkinson’s disease dementia, but cognitive impairment precedes or coincides with motor onset. It remains controversial whether dementia with Lewy bodies and Parkinson’s disease dementia are distinct conditions or represent part of a disease spectrum. The biological mechanisms underlying disease heterogeneity, in particular the development of dementia, remain poorly understood, but will likely be key to understanding disease pathways and ultimately therapy development. Previous genome-wide association studies in Parkinson’s disease and dementia with Lewy bodies/Parkinson’s disease dementia have identified risk loci differentiating patients from controls. We collated data for 7,804 patients of European ancestry from Tracking Parkinson’s (PRoBaND), The Oxford Discovery Cohort, and AMP-PD. We conducted a discrete phenotype genome-wide association studies comparing Lewy body diseases with and without dementia to decode disease heterogeneity by investigating the genetic drivers of dementia in Lewy body diseases. We found that risk alleles rs429358 taggingAPOEe4and rs7668531 near theMMRN1and SNCA-AS1 genes, increase the odds of developing dementia and that an intronic variant rs17442721 taggingLRRK2G2019S, on chromosome 12 is protective against dementia. These results should be validated in autopsy confirmed cases in future studies.
The unique face of anxious depression: Increased sustained threat circuitry response during fear acquisition
Authors: Poplin Tate , Ironside Maria , Kuplicki Rayus , Aupperle Robin L. , Guinjoan Salvador M. , Khalsa Sahib S. , Stewart Jennifer L. , Victor Teresa A. , Paulus Martin P. , Kirlic Namik
Published: October 2023

Background

Sensitivity to threat with dysregulation of fear learning is thought to contribute to the development of psychiatric disorders, including anxiety disorders (AD) and major depressive disorder (MDD). However, fewer studies have examined fear learning in MDD than in AD. Nearly half of individuals with MDD have an AD and the comorbid diagnosis has worse outcomes. The current study used propensity matching to examine the hypothesis that AD+MDD shows greater neural correlates of fear learning than MDD, suggesting that the co-occurrence of AD+MDD is exemplified by exaggerated defense related processes.

Methods

195 individuals with MDD (N = 65) or AD+MDD (N=130) were recruited from the community and completed multi-level assessments, including a Pavlovian fear learning task during functional imaging.

Results

MDD and AD+MDD showed significantly different patterns of activation for [CSplus– CSminus] in the medial amygdala (ηp2=0.009), anterior insula (ηp2=0.01), dorsolateral prefrontal cortex (ηp2=0.002), dorsal anterior cingulate cortex (ηp2=0.01), mid-cingulate cortex (ηp2=0.01) and posterior cingulate cortex (ηp2=0.02). These differences were driven by greater activation to the CS+ in late conditioning phases in ADD+MDD relative to MDD.

Conclusions

AD+MDD showed a pattern of increased sustained activation in regions identified with fear learning. Effects were consistently driven by the threat condition, further suggesting fear signaling as the emergent target process. Differences emerged in regions associated with salience processing, attentional orienting/conflict, and self-relevant processing. These findings help to elucidate the fear signaling mechanisms involved in the pathophysiology of comorbid anxiety and depression, thereby highlighting promising treatment targets for this prevalent treatment group.
Multiformity of extracellular microelectrode recordings from Aδ neurons in the dorsal root ganglia: A computational modeling study
Authors: Madden Lauren R. , Graham Robert D. , Lempka Scott F. , Bruns Tim M.
Published: October 2023

Microelectrodes serve as a fundamental tool in electrophysiology research throughout the nervous system, providing a means of exploring neural function with a high resolution of neural firing information. We constructed a hybrid computational model using the finite element method and multi-compartment cable models to explore factors that contribute to extracellular voltage waveforms that are produced by sensory pseudounipolar neurons — specifically, smaller A-type neurons — and that are recorded by microelectrodes in dorsal root ganglia. The finite element method model included a dorsal root ganglion, surrounding tissues, and a planar microelectrode array. We built a multi-compartment neuron model with multiple trajectories of the glomerular initial segment found in many A-type sensory neurons. Our model replicated both the somatic intracellular voltage profile of Aδ low-threshold mechanoreceptor neurons and the unique extracellular voltage waveform shapes that are observed in experimental settings. Results from this model indicated that tortuous glomerular initial segment geometries can introduce distinct multiphasic properties into a neuron’s recorded waveform. Our model also demonstrated how recording location relative to specific microanatomical components of these neurons, and recording distance from these components, can contribute to additional changes in the multiphasic characteristics and peak-to-peak voltage amplitude of the waveform. This knowledge may provide context for research employing microelectrode recordings of pseudounipolar neurons in sensory ganglia, including functional mapping and closed-loop neuromodulation. Further, our simulations gave insight into the neurophysiology of pseudounipolar neurons by demonstrating how the glomerular initial segment aids in increasing the resistance of the stem axon and mitigating rebounding somatic action potentials.
Cryo-EM structure of the CDK2-cyclin A-CDC25A Complex
Authors: Rowland Rhianna J. , Korolchuk Svitlana , Salamina Marco , Ault James R. , Hart Sam , Turkenburg Johan P. , Blaza James N. , Noble Martin E.M. , Endicott Jane A.
Published: October 2023

The cell division cycle 25 phosphatases CDC25A, B and C regulate cell cycle transitions by dephosphorylating residues in the conserved glycine-rich motif of cyclin-dependent protein kinases (CDKs) to activate CDK activity. Here, we present the cryogenic-electron microscopy (cryo-EM) structure of CDK2-cyclin A in complex with CDC25A at 2.91 Å resolution, providing a detailed structural analysis of the overall complex architecture and key protein-protein interactions that underpin this 86 kDa complex. We further reveal an unanticipated CDC25A C-terminal helix that is critical for complex formation. Sequence conservation analysis suggests CDK1/2-cyclin A, CDK1-cyclin B and CDK2/3-cyclin E are suitable binding partners for CDC25A, whilst CDK4/6-cyclin D complexes appear unlikely substrates. A comparative structural analysis of CDK-containing complexes also confirms the functional importance of the conserved CDK1/2 GDSEID motif. This structure improves our understanding of the roles of CDC25 phosphatases in CDK regulation and may inform the development of CDC25- targeting anticancer strategies.
Diet composition and sterilization modifies intestinal microbiome diversity and burden of Theiler’s virus infection-induced acute seizures
Authors: Zierath Dannielle K. , Davidson Stephanie , Manoukian Jonathan , White H. Steve , Meeker Stacey , Ericsson Aaron , Barker-Haliski Melissa
Published: October 2023

Objective

Central nervous system infection with Theiler’s murine encephalomyelitis virus (TMEV) in C57BL/6J mice can model acquired epileptogenesis. Diet alters the acute seizure incidence in TMEV-infected mice; yet it is unclear whether intestinal dysbiosis may also impact acute or chronic behavioral comorbidities. This study thus assessed the impact of diet sterilization in a specific pathogen-free vivarium on acute seizure presentation, the composition of the gut microbiome, and chronic behavioral comorbidities of epilepsy.

Methods

Baseline fecal samples were collected from male C57BL/6J mice (4-5 weeks-old; Jackson Labs) upon arrival. Mice were randomized to either autoclaved (AC) or irradiated (IR) diet (Prolab RMH 3000 – UU diets) or IR (Picolab 5053 – UW IR diet). Mice then underwent intracerebral TMEV or PBS injection three days later. Fecal samples were collected from a subset of mice at infection (Day 0) and Day 7 post-infection. Epilepsy-related working memory deficits and seizure threshold were assessed 6 weeks post-infection. Gut microbiome diversity was determined by 16S rRNA amplicon sequencing of fecal samples.

Results

TMEV-infected mice displayed acute handling-induced seizures, regardless of diet: 28/57 UW IR (49.1%), 30/41 UU IR (73.2%), and 47/77 UU AC (61%) mice displayed seizures. The number of observed seizures significantly differed: UW IR mice had 2.2±2.8 seizures (mean±standard deviation), UU IR mice had 3.5±2.9 seizures, and UU AC mice had 4.4±3.8 seizures during the 7-day monitoring period. The composition of the gut microbiome significantly differed in TMEV-infected mice fed the UU AC diet, with most measured differences occurring in Gram-positive bacteria. TMEV-infected mice fed the UU AC diet displayed worsened chronic working memory.

Significance

Intestinal dysbiosis evokes stark differences in acute seizure presentation in the TMEV model and vastly influences the trajectory of post-TMEV infection-induced behavioral comorbidities of epilepsy. Our study reveals a novel disease-modifying contribution of intestinal bacterial species after TMEV-induced acute seizures.
Zigzag materials: Selective interchain couplings control the coexistence of one-dimensional physics and deviations from it
Authors: Carmelo J. M. P. , Sacramento P. D. , Stauber T. , Campbell D. K.
Published: October 2023

The coexistence in the low-temperature spin-conducting phases of the zigzag materials BaCo2V2O8 and SrCo2V2O8 of one-dimensional (1D) physics with important deviations from it is not well understood. The studies of this paper account for an important selection rule that follows from interchain spin states being coupled more strongly within the spin dynamical structure factor of such zigzag materials whenever they are connected by a specific symmetry operation of the underlying lattice. In the case of excited states, this symmetry operation is only a symmetry in spin space if no electronic spin flip is performed within the generation of such states. The corresponding selective interchain couplings both protect the 1D physics and are behind important deviations from it concerning the enhancement of the spectral-weight intensity of Szz(k,ω). Strong evidence is provided that this justifies, beyond interchain mean-field theory and in contrast to 1D physics, the experimental low-energy dominance in both zigzag materials of the longitudinal nuclear magnetic resonance relaxation rate term 1/T1∥ for the whole magnetic field interval of the spin-conducting phases. To further understand the role of selective interchain couplings concerning their contradictory effects in protecting the 1D physics and controlling deviations from it, the physical-spins scattering processes behind the experimentally observed sharp peaks in the dynamic structure factor components are investigated. Indeed, the experimentally observed Bethe strings in S+−(k,ω) cannot be expressed in terms of configurations of usual spinons. We find that the line shape at and near the sharp peaks of the spin dynamic structure factor experimentally observed in BaCo2V2O8 and SrCo2V2O8 is fully controlled by unbound-unbound and unbound-bound scattering of singlet pairs of physical spins 1/2. Our results on both the role of selective interchain couplings in protecting the 1D physics and being behind deviations from it and on the dynamical properties being controlled by scattering of singlet pairs of physical spins 1/2 open the door to a key advance in the understanding of the physics of the spin chains in BaCo2V2O8 and SrCo2V2O8.

Published by the American Physical Society
2023
Correction and integration of solid-angle data from the azimuthally resolving 2D detector at ID06-LVP, ESRF
Authors: Crichton Wilson A. , Kieffer Jérôme , Wattecamps Pierre , Valls Valentin , Berruyer Gilles , Ruat Marie , Favre-Nicolin Vincent
Published: October 2023

The unique diffraction geometry of ESRF beamline ID06-LVP offers continuous static 2D or azimuthally resolving data collections over all accessible solid angles available to the tooling geometry. The system is built around a rotating custom-built Pilatus3 CdTe 900k-W detector from Dectris, in a configuration equivalent to three butted 300k devices. As a non-standard geometry, here the method of alignment, correction and subsequent integration for any data collected over all solid angles accessible, or over any azimuthal range contained therein, are provided and illustrated by parameterizing and extending existing pyFAI routines. At 1° integrated intervals, and typical distances (2.0 m), the system covers an area of near 2.5 m2 (100 Mpx square equivalent), to 0.65 Å resolution, at 53 keV from a total dataset of some 312 Mpx. Standard FWHMs of SRM660a LaB6 vary from 0.005° to 0.01°, depending on beam size, energy and sample dimensions, and are sampled at an elevated rate. The azimuthal range per static frame ranges from <20° to ∼1° over the full range of the detector surface. A full 2θ–intensity data collection at static azimuth takes 1–3 s typically, and can be reduced to ms−1 rates for measurements requiring time-rate determination. A full solid-angle collection can be completed in a minute. Sample detector distances are accessible from 1.6 m to 4.0 m.
Innovation in the tourism sector, organizational learning and performance
Authors: Galarza Iván Santiago , León-Carlosama Rocío Guadalupe , Cevallos-Pineda Alba Grisela , Martínez-Gómez Mónica
Published: October 2023

Purpose

The purpose of this research paper is to establish the impact of process and service innovation on non-financial and financial performance in the tourism sector, as well as to explain the mediating role of organizational learning.

Design/methodology/approach

A quantitative approach was used, based on partial least squares–structural equation modeling (PLS-SEM), Smart PLS 4.0 software. The sample consisted of 426 establishments in the tourism sector in Zone I, Ecuador. Online surveys were employed to collect data, yielding 118 responses, to assess the impact of innovation on business performance from 2020 to 2022.

Findings

Process and service innovation positively and significantly affect non-financial and financial performance, respectively. Organizational learning mediates the relationship between process innovation and disservice. The relationship between non-financial and financial performance could not be confirmed. The model explains 53.10% of non-financial performance and 26.10% of financial performance.

Originality/value

The relationship between innovation and performance in the tourism sector has been studied in several developed economies, while little has been studied in developing countries. This work contributes to an empirical discussion including a mediating variable in the innovation–performance relationship in the Latin American context.
Crowding-based multi-objective artificial gorilla troops optimizer for brushless direct current motor design optimization
Authors: Bensoltane Hadjaissa , Belli Zoubida
Published: October 2023

Purpose

This paper aims to present a novel multi-objective version of the Gorilla Troops optimizer (GTO), based on crowding distance, to achieve the optimal design of a brushless direct current motor.

Design/methodology/approach

In the proposed algorithm, the crowding distance technique was integrated into the GTO to perform the leader selection and also for the external archive refinement from extra non-dominated solutions. Furthermore, with a view to improving the diversity of non-dominated solutions in the external archive, mutation operator was used. For constrained problems, an efficient strategy was adopted. The proposed algorithm is referred to as CD-MOGTO.

Findings

To validate the effectiveness of the proposed approach, it was initially tested on three constrained multi-objective problems; thereafter, it was applied to optimize the design variables of brushless direct current motor to concurrently fulfill six inequality constraints, maximize efficiency and minimize total mass.

Originality/value

The results revealed the high potential of the proposed algorithm over different recognized algorithms in solving constrained multi-objective issues and the brushless direct current motors.
Why is a modest gentleman cruel and ruthless? A study on the dark side effect of humble leadership – from the perspective of low-status compensation theory
Authors: Chen Hao , Jiang Jianming , Wang Liang , Zhang Zihan , Bao Jiaying
Published: October 2023

Purpose

The purpose of this study is to reveal the mechanism of humble leadership inducing abusive supervision from the low-status compensation perspective, examining the mediation role of leader perceived thread to status. Besides, the moderation effect of regulatory focus on the mediation path is discussed.

Design/methodology/approach

This study conducted a three-wave longitudinal survey. The data was collected from 438 leaders and their employees in five Chinese enterprises. This study used Mplus 7.4 and adopted a bootstrapping technique for data analysis.

Findings

Humble leadership has a positive effect on leader perceived threat to status. Leader perceived threat to status plays a mediation role between humble leadership and leader abusive supervision. Leader regulatory focus is the “gate valve” that humble leadership fosters leader abusive supervision. That is, when the leader promotion focus is high, leader perceived threat to status bred by humble leadership is low, resulting in less abusive supervision. When the leader prevention focus is high, humble leadership brings relatively more abusive supervision through perceived threat to status.

Originality/value

This study explores why humble leadership breeds abusive supervision behaviors and reveals the mechanism behind the negative effect of humble leadership based on low-status compensation theory. This study not only promotes the continuous development of the field of humble leadership research through empirical research but also provides guidance for effectively suppressing the negative effects of humble leadership, promoting strengths and avoiding weaknesses and suppressing inappropriate management behaviors in management practice.
The dynamic effect of public debt on economic growth in the era of Macroprudential policy regime: a Bayesian approach
Authors: Ngcobo Thembeka Sibahle , Zungu Lindokuhle Talent , Nkomo Nomusa Yolanda
Published: October 2023

Purpose

This study aims to test the dynamic impact of public debt and economic growth on newly democratized African countries (South Africa and Namibia) and compare the findings with those of newly democratized European countries (Germany and Ukraine) during the period 1990–2022.

Design/methodology/approach

The methodology involves three stages: identifying the appropriate transition variable, assessing the linearity between public debt and economic growth and selecting the order m of the transition function. The linearity test helps identify the nature of relationships between public debt and economic growth. The wild cluster bootstrap-Lagrange Multiplier test is used to evaluate the model’s appropriateness. All these tests would be executed using the Lagrange Multiplier type of test.

Findings

The results signify the policy switch, as the authors find that the relationship between public debt and economic growth is characterized by two transitions that symbolize that the current stage of the relationship is beyond the U-shape; however, an S-shape. The results show that for newly democratized African countries, the threshold during the first waves was 50% of GDP, represented by a U-shape, which then transits to an inverted U-shape with a threshold of 65% of GDP. Then, for the European case, it was 60% of GDP, which is now 72% of GDP.

Originality/value

The findings suggest that an escalating level of public debt has a negative impact on economic growth; therefore, it is important to implement fiscal discipline, prioritize government spending and reduce reliance on debt financing. This can be achieved by focusing on revenue generation, implementing effective taxation policies, reducing wasteful expenditures and promoting investment and productivity-enhancing measures.
Curating pasts: musealization and tourism in Chinese cities
Authors: Luo Wenhong , Graburn Nelson
Published: October 2023

Purpose

China has been going through a “museum boom” paralleling the domestic tourism boom since 2000; such growth changed the cultural landscape; museums became a vital characteristic of some Chinese cities for both residents and tourists. Encouraged by this growth, the more ambitious “All-for-one Museum (全域博物馆)” was proposed. The physical boundary between museums and living spaces is infinite ambiguity, challenging the idea of museums as “heterotopias.” This study aims to explore the musealization of urban spaces in the context of anthropology and museology, scrutinizing the cultural-political intentions and meanings of these developments, and seeks to ignite further investigation into the reconstruction of historical imaginaries for tourists and urban populations across related disciplines.

Design/methodology/approach

This paper examines two cases in Chinese metropolises, Beijing and Shanghai, to illustrate this development of musealization, that is, how the cities actively leverage museological values and methods to connect with their past. In the Beijing case, the authors explore how the local government is leading the effort to musealize the city; in the Shanghai case, they will see how tourists, especially dweller-tourists, navigate through a curated past story in the city and connect their own experience, memory and identity with the place.

Findings

The all-for-one museum creates a museal layer projected onto the bigger urban space, even though the authenticity of the “past” is challenged by the modernization development of the city. The authors also find out that for some tourists (especially dweller-tourists), an existential sense of authenticity plays a more significant role as they not only seek to sightsee the past of the city but also to take part in its creation.

Originality/value

This paper discusses two kinds of musealization in cosmopolitan cities of Beijing and Shanghai: top-down and bottom-up. It approaches questions about the musealization of urban spaces from the perspectives of anthropology and museology, and discusses musealization in the specific historical context of China’s modernization process.
The effect of wine tourism on the sustainable performance of Spanish wineries: a structural equation model analysis
Authors: Martínez-Falcó Javier , Marco-Lajara Bartolomé , Zaragoza-Sáez Patrocinio , Sánchez-García Eduardo
Published: October 2023

Purpose

The purpose of this study is to analyze the effect of wine tourism on the economic, social and environmental performance, i.e. the sustainable performance, of Spanish wineries. In addition, age, size and membership in the protected designation of origin are introduced as control variables to increase the precision of the cause-effect relationships analyzed.

Design/methodology/approach

A conceptual model is proposed, which is tested by means of structural equation modeling based on data from a survey of 202 Spanish wineries.

Findings

The results indicate the existence of a positive and significant link between wine tourism activities and the three performance typologies analyzed in the Spanish wine context.

Originality/value

The study contributes to the academic literature on wine tourism in a remarkable way, as, to the best of the authors’ knowledge, there is no previous literature that has addressed the effect of wine tourism on the sustainable performance of Spanish wineries, making the study useful for both academics and wine professionals who are considering the implementation or development of this typology of tourism in their facilities.
Juror decision-making within domestic sex trafficking cases: do pre-trial attitudes, gender, culture and right-wing authoritarianism predict believability assessments?
Authors: Stevens Kay Lynn , Mojtahedi Dara , Austin Adam
Published: October 2023

Purpose

This study aims to examine whether country of residence, sex trafficking attitudes, complainant gender, juror gender and right-wing authoritarianism (RWA) influenced juror decision-making within a sex trafficking case.

Design/methodology/approach

Jury-eligible participants from the USA and the UK participated in an online juror experiment in which an independent group design was used to manipulate the complainant’s gender. Participants completed the juror decision scale, the sex trafficking attitudes scale and the RWA scale.

Findings

Sex trafficking attitudes predicted the believability of both the defendant and complainant. Greater negative beliefs about victims predicted greater defendant believability and lower complainant believability. US jurors reported greater believability of both the complainant and defendant, and RWA was associated with greater defendant believability. However, none of the other factors, including complainant and juror gender, predicted participants’ verdicts. The findings suggest juror verdicts in sex trafficking cases may be less influenced by extra-legal factors, although further research is needed, especially with a more ambiguous case.

Originality/value

This is one of the few cross-cultural comparison studies in the area of jury decision-making, specifically regarding sex trafficking cases. The findings indicated that US participants held more problematic attitudes about sex trafficking than their UK counterparts, although all participants held problematic attitudes about sex trafficking. However, those attitudes did not affect verdict formation about either a male or female complainant. Participants who were more knowledgeable about sex trafficking reported greater complainant believability, suggesting that educational interventions may provide greater support for victims in court.
Determinants, processes, and impacts of indigenous entrepreneurship: a systematic literature review
Authors: AlMehrzi Aaesha Ahmed , Tipu Syed Awais , Sarker Abu Elias
Published: October 2023

Purpose

This paper aims to provide a systematic review of the academic literature on the determinants, processes and impacts of indigenous entrepreneurship (IE), highlights its contribution to current knowledge and identifies research gaps to guide future research.

Design/methodology/approach

Databases used in this study included Scopus, ABI, Business Source Complete, ProQuest and Emerald Insight. In total, 84 articles were included in the review.

Findings

The findings revealed that 33 studies were qualitative, 12 used a survey-based approach, 25 were conceptual and 14 used mixed approaches. The focus on theory-building research underlines the fact that more theory-testing research is needed in the future. In total, 38 studies were conducted in developed countries and 43 in developing countries. The findings indicated that IE was driven by many determinants such as family and clan ties, patriarchy and social stratification, government support and conducive entrepreneurial ecosystems. Processes related to policies, IE development programs, partnerships, expenditure mechanisms, equitable distribution of benefits and resource mobilization. The outcomes of IE included economic development, sustainability, increased indigenous economic participation, enhanced quality of life, self-determination and preserving cultural heritage.

Research limitations/implications

The current paper has some limitations. Firstly, it focuses only on academic journals and excludes conferences, books and working papers. Secondly, it includes only English language academic articles. However, while the current systematic literature review (SLR) has these limitations, it presents a thorough view of the determinants, processes and impacts of IE. Future studies may consider other sources beyond academic journals and also include non-English publications, and this approach may identify interesting areas for future research.

Originality/value

Existing reviews of IE take a narrow perspective and fail to present a comprehensive view of the IE phenomenon. The current study aims to fill this gap in the literature and provides a SLR pertaining to IE’s determinants, processes and impacts. The review is both timely and relevant because it identifies gaps and serves as a springboard to guide future research.