Small-scale Events Research Articles

Gender Bias in Residents’ Perceptions and Support of Rally Event Tourism: The Sierra Morena Rally of Córdoba, Spain

Motorsports have become a tourism resource for certain territories. Knowledge about the perception of impact and the support residents provide for their celebration contributes to ensuring their long-term success. The academic literature has so far focused on large-scale events, leaving a gap in knowledge regarding small-scale events. This study addresses the case of the Sierra Morena Rally in Córdoba, Spain. It is based on the principles of Social Exchange Theory (SET) and Social Representation Theory (SRT) to explore a gender bias in the perception of impact and support for the event. Using a sample of 753 residents, an Exploratory Factor Analysis is conducted, and Mann–Whitney U and Hedges’ G statistics are applied. The results confirm the existence of a gender bias in perception, which is discussed in the context of previous case studies.

Association between the number of individuals injured in a traumatic event and posttraumatic stress disorder among hospitalized trauma patients.

Posttraumatic stress disorder (PTSD) often occurs following mass casualty events, yet the connection between the number of individuals injured in an event and PTSD risk in smaller-scale events (i.e., involving one or several injured persons)remains unclear. We conducted a registries-based study cross-referencing three databases across the continuum of care for military trauma patients hospitalized for traumatic injuries. The study population was categorized into three groups based on the number of injured individuals involved (i.e., single injured person, two to four [2-4] injured people, and five or more [≥ 5] injured people), and PTSD prevalence was assessed using long-term disability claim diagnoses. Overall, 4,030 military personnel were included (age at injury: Mdn = 20 years), and 18.3% were subsequently diagnosed with PTSD, with the highest prevalence in events involving ≥ 5 injured individuals (35.8%). Regression analyses adjusted for potential confounders revealed that being injured in an event with 2-4 injured persons, OR = 1.68, 95% CI [1.31, 2.15], or ≥ 5 injured persons, OR = 2.36, 95% CI [1.79, 3.13], was associated with increased odds of developing PTSD compared to being the sole injured person. The findings suggest a direct association between the number of injured individuals in an event and PTSD prevalence among traumatic injury survivors. The results underscore the importance of early diagnosis and interventions to prevent PTSD in individuals injured in multicasualty and mass casualty events.

Widespread mutagenesis and chromosomal instability shape somatic genomes in systemic sclerosis

Systemic sclerosis is a connective tissue disorder characterized by excessive fibrosis that primarily affects women, and can present as a multisystem pathology. Roughly 4-22% of patients with systemic sclerosis develop cancer, which drastically worsens prognosis. However, the mechanisms underlying systemic sclerosis initiation, propagation, and cancer development are poorly understood. We hypothesize that the inflammation and immune response associated with systemic sclerosis can trigger DNA damage, leading to elevated somatic mutagenesis, a hallmark of pre-cancerous tissues. To test our hypothesis, we culture clonal lineages of fibroblasts from the lung tissues of controls and systemic sclerosis patients and compare their mutation burdens and spectra. We find an overall increase in all major mutation types in systemic sclerosis samples compared to control lung samples, from small-scale events such as single base substitutions and insertions/deletions, to chromosome-level changes, including copy-number changes and structural variants. In the genomes of patients with systemic sclerosis, we find evidence of somatic hypermutation or kategis (typically only seen in cancer genomes), we identify mutation signatures closely resembling the error-prone translesion polymerase Polη activity, and observe an activation-induced deaminase-like mutation signature, which overlaps with genomic regions displaying kataegis.

Different manifestations of a loop-like transient brightening in solar atmospheres

Small-scale transient brightenings that are the consequence of magnetic reconnection play pivotal roles in the heating process of solar atmospheres. These phenomena contain key information about the dynamic evolution of the solar magnetic field. The fine-scale structures triggered by instabilities in these brightenings are intimately connected with the release of magnetic energy. To better understand the conversion and release of magnetic energy in small-scale heating events, we investigated the thermal-dynamical behaviors of a loop-like transient brightening (LTB) with plasma blobs. We used the spectroscopic and slit-jaw imaging observations taken from the Interface Region Imaging Spectrograph and the extreme-ultraviolet images taken from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to analyze the plasma properties of an LTB that occurred on February 28, 2014. The space-time maps were created to present the spatial evolution of the LTB, and the light curves were calculated to illustrate the heating process. Additionally, we employed the differential emission measure (DEM) method to compute the temperature and emission measure of the LTB. In order to investigate the plasma motion along the line-of-sight direction, a double-Gaussian function was used to fit the Si IV spectral profiles. The spectrum and DEM analysis indicate that the LTB was constituted by multithermal plasma with temperatures reaching up to $5.4 $ K. The space-time maps of the emission and the Gaussian-fitting results of the Si IV line demonstrate that the LTB not only exhibited bidirectional flows, but was also twisted. Several plasma blobs were identified in the spine of the LTB, suggesting the potential presence of a tearing-mode instability. The low-temperature bands peaked approximately one minute prior to the high-temperature bands, suggesting the occurrence of a heating process driven by magnetic reconnection. The appearance of plasma blobs closely coincided with the sudden increase in the velocity and the quick rise of light curves, providing evidence that plasma blobs facilitate the release of magnetic energy during solar activity. Based on these findings, we speculate that the LTB was a complex structure that occurred in the upper chromosphere-transition region. These results clearly demonstrate that plasma blobs are important for the conversion and release processes of magnetic energy.

Genome-Wide Characterization of Alfin-like Genes in Brassica napus and Functional Analyses of BnaAL02 and BnaAL28 in Response to Nitrogen and Phosphorus Deficiency.

Alfin-like proteins (ALs) form a plant-specific transcription factor (TF) gene family involved in the regulation of plant growth and development, and abiotic stress response. In this study, 30 ALs were identified in Brassica napus ecotype 'Zhongshuang 11' genome (BnaALs), and unevenly distributed on 15 chromosomes. Structural characteristic analysis showed that all of the BnaALs contained two highly conserved domains: the N terminal DUF3594 domain and the C-terminal PHD-finger domain. The BnaALs were classified into four groups (Group I-IV), supported by conserved intron-exon and protein motif structures in each group. The allopolyploid event between B. oleracea and B. rapa ancestors and the small-scale duplication events in B. napus both contributed to the large BnaALs expansion. The promoter regions of BnaALs contained multiple abiotic stress cis-elements. The BnaALs in I-IV groups were mainly expressed in cotyledon, petal, root, silique, and seed tissues, and the duplicated gene pairs shared highly similar expression patterns. RNA-seq and RT-qPCR analysis showed that BnaALs were obviously induced by low nitrogen (LN) and low phosphorus (LP) treatments in roots. Overexpressing BnaAL02 and BnaAL28 in Arabidopsis demonstrated their functions in response to LN and LP stresses. BnaAL28 enhanced primary roots' (PRs) length and lateral roots' (LRs) number under LP and LN conditions, where BnaAL02 can inhibit LR numbers under the two conditions. They can promote root hair (RH) elongation under LP conditions; however, they suppressed RH elongation under LN conditions. Our result provides new insight into the functional dissection of this family in response to nutrient stresses in plants.

Transition region response to quiet-Sun Ellerman bombs

Context. Quiet-Sun Ellerman bombs (QSEBs) are key indicators of small-scale photospheric magnetic reconnection events. Recent high-resolution observations have shown that they are ubiquitous and that large numbers of QSEBs can be found in the quiet Sun. Aims. We aim to understand the impact of QSEBs on the upper solar atmosphere by analyzing their spatial and temporal relationship with the UV brightenings observed in transition region diagnostics. Methods. We analyzed high-resolution Hβ observations from the Swedish 1-m Solar Telescope and utilized k-means clustering to detect 1423 QSEBs in a 51 min time series. We used coordinated and co-aligned observations from the Interface Region Imaging Spectrograph (IRIS) to search for corresponding signatures in the 1400 Å slit-jaw image (SJI) channel and in the Si IV 1394 Å and Mg II 2798.8 Å triplet spectral lines. We identified UV brightenings from SJI 1400 using a threshold of 5σ above the median background. Results. We focused on 453 long-lived QSEBs (> 1 min) and found 67 cases of UV brightenings from SJI 1400 occurring near the QSEBs, both temporally and spatially. Temporal analysis of these events indicates that QSEBs start before UV brightenings in 57% of cases, while UV brightenings lead in 36% of instances. The majority of the UV brightenings occur within 1000 km of the QSEBs in the direction of the solar limb. We also identify 21 QSEBs covered by the IRIS slit, four of which show emissions in the Si IV 1394 Å and/or Mg II 2798.8 Å triplet lines, at distances within 500 km of the QSEBs in the limb direction. Conclusions. We conclude that a small fraction (15%) of the long-lived QSEBs contribute to the localized heating observable in transition region diagnostics, indicating they play a minimal role in the global heating of the upper solar atmosphere.

The role of sports on destination branding: A bibliometric study

The role of sports in place branding is growing interest in literature. To orientate future research on this topic, the present paper aims: (a) to measure the visibility and impact of the scientific production on the topic, and (b) to identify the scientific structure by research themes, as well as its evolution in two different periods. To this end, 135 papers linking sports with a destination image were retrieved from the Web of Science. Two periods were compared (2003–2012; 2013–2022). Our results show future research opportunities for (a) new small-scale sporting events beyond big mega-events; (b) residents’ perspective beyond tourists’ approach, (c) sports focused on minority audiences beyond football and the Olympics, (d) studies focused on European countries, beyond Brazil, China, USA and Israel; (e) a higher focused on sports teams and clubs beyond sports events; and (f) attention to public administrations responsibilities beyond private companies.

Direct observational evidence of strong CO2 uptake in the Southern Ocean.

The Southern Ocean is the primary region for the uptake of anthropogenic carbon dioxide (CO2) and is, therefore, crucial for Earth's climate. However, the Southern Ocean CO2 flux estimates reveal substantial uncertainties and lack direct validation. Using seven independent and directly measured air-sea CO2 flux datasets, we identify a 25% stronger CO2 uptake in the Southern Ocean than shipboard dataset-based flux estimates. Accounting for upper ocean temperature gradients and insufficient temporal resolution of flux products can bridge this flux gap. The gas transfer velocity parameterization is not the main reason for the flux disagreement. The profiling float data-based flux products and biogeochemistry models considerably underestimate the observed CO2 uptake, which may be due to the lack of representation of small-scale high-flux events. Our study suggests that the Southern Ocean may take up more CO2 than previously recognized, and that temperature corrections should be considered, and a higher resolution is needed in data-based bulk flux estimates.

Detecting abnormal small-scale events by nacelle lidar at the AD8-180 prototype turbine

Identifying anomalous wind events that lead to high aerodynamic loads is essential for mitigating extreme loading on wind turbines. Building upon a recently published method, we herein introduce an extended methodology for early small-scale abnormal wind event detection employing a pulsed nacelle-lidar, potentially triggering preemptive control actions within the wind turbine system. The extended method integrates the consideration of multiple measurement ranges within the induction zone and the evaluation of a horizontally asymmetric wind detection parametrized through a difference in lidar line-of-sight (LoS) measurements. A comparative assessment of various detection algorithms is conducted, leading to the identification of optimal parameter configurations and an evaluation of their reliability. With the proposed methodology, the false positive rate can be reduced with respect to the original methodology, although not all extreme loading events are detected.

Dynamic near-seafloor sediment transport in Kaikōura Canyon following a large canyon-flushing event

ABSTRACT Submarine canyons are important deep-sea environments and conduits for transferring and accumulating sediment and organic matter and pollutants. Recent advances in observing, sampling, and analyzing modern canyon sediment transport systems illustrate near-seafloor dynamics and highlight the potential roles of submarine canyons in transporting and storing organic carbon, nutrients, and contaminants in the deep sea, with implications for deep-sea ecosystems and global carbon budgets. Kaikōura Canyon, offshore northeastern Te Waipounamu South Island, Aotearoa New Zealand, is a benthic biomass hotspot that experienced an earthquake-triggered, canyon-flushing event in 2016. On return to the canyon in October 2020, benthic landers, with sediment traps at 2 m above the seafloor, were deployed along the canyon axis in ∼ 900–1500 m water depths for a period of three weeks. These instrumented platforms provide a detailed view of near-seafloor sediment and organic-carbon transport between canyon-flushing events, showing that the canyon environment hosts dynamic physical processes and short-term sediment fluxes and transport. Variations in sediment and organic carbon flux down-canyon and over time include small-scale sediment transport events, some of which are interpreted as turbidity currents, occurring on much shorter timescales than earthquake recurrence. We compare Kaikōura Canyon results with other longshore-fed, shelf-incised global submarine canyons and deep-ocean sites, revealing differences and likely multiple controlling factors for near-seafloor sediment flux. This Kaikōura Canyon high-resolution, benthic lander timeseries dataset highlights the complexity of submarine canyons and their role in organic carbon flux to the deep ocean, even under high present-day sea-level conditions. Evolving insights underscore the need for more observational data and samples to further quantify submarine canyon sediment and organic-carbon transport and contribute to global evaluations of deep-sea canyon distributary systems.

Sport tourist perceptions of destination image and revisit intentions: An adaption of Mehrabian-Russell's environmental psychology model

In environmental psychology literature, an individual's perception of the surroundings leads to subsequent behaviors. In this regard, small-scale sport events (SSE) have been used as a marketing tool for tourism development. However, how SSEs are leveraged to improve destination image (DI) for tourists has not been fully understood. Building on Mehrabian-Russell's environmental psychology model, this study examined the relationship between the SSE environmental stimuli and revisit intentions through the sequential mediation of cognitive and affective DI. Data from the 423 respondents were collected from 2023 Wuxi Marathon held in Wuxi, China. Structural equation modeling was employed to analyze the hypothesized framework. The results indicated that the SSE environmental stimuli were positively associated with both cognitive and affective DI, which were positively correlated with revisit intentions. The applicability of the serial mediation of cognitive and affective DI within the relationship was confirmed. This study contributes to the sport and tourism literature by extending the applicability of Mehrabian and Russell's model to SSE settings and identifying the serial mediating effects of cognitive and affective DI.

MUSE observations of small-scale heating events

ABSTRACT Constraining the processes that drive coronal heating from observations is a difficult task due to the complexity of the solar atmosphere. As upcoming missions such as the Multi-slit Solar Explorer (MUSE) will provide coronal observations with unprecedented spatial and temporal resolution, numerical simulations are becoming increasingly realistic. Despite the availability of synthetic observations from numerical models, line-of-sight effects and the complexity of the magnetic topology in a realistic set-up still complicate the prediction of signatures for specific heating processes. 3D magnetohydrodynamic (MHD) simulations have shown that a significant part of the Poynting flux injected into the solar atmosphere is carried by small-scale motions, such as vortices driven by rotational flows inside intergranular lanes. MHD waves excited by these vortices have been suggested to play an important role in the energy transfer between different atmospheric layers. Using synthetic spectroscopic data generated from a coronal loop model incorporating realistic driving by magnetoconvection, we study whether signatures of energy transport by vortices and eventual dissipation can be identified with future missions such as MUSE.

Small-scale magnetic flux emergence preceding a chain of energetic solar atmospheric events

Advancements in instrumentation have revealed a multitude of small-scale extreme-ultraviolet (EUV) events in the solar atmosphere and considerable effort is currently undergoing to unravel them. Our aim is to employ high-resolution and high-sensitivity magnetograms to gain a detailed understanding of the magnetic origin of such phenomena. We used coordinated observations from the Swedish 1-m Solar Telescope (SST), the Interface Region Imaging Spectrograph ( and the Solar Dynamics Observatory ( to analyze an ephemeral magnetic flux emergence episode and the following chain of small-scale energetic events. These unique observations clearly link these phenomena together. The high-resolution (0 $) magnetograms obtained with SST/CRISP allowed us to reliably measure the magnetic field at the photosphere and to detect the emerging bipole that caused the subsequent eruptive atmospheric events. Notably, this small-scale emergence episode remains indiscernible in the lower resolution SDO/HMI magnetograms (0 $). We report the appearance of a dark bubble in related to the emerging bipole, a sign of the canonical expanding magnetic dome predicted in flux emergence simulations. Evidence of reconnection are also found, first through an Ellerman bomb and later by the launch of a surge next to a UV burst. The UV burst exhibits a weak EUV counterpart in the coronal SDO/AIA channels. By calculating the differential emission measure (DEM), its plasma is shown to reach a temperature beyond 1 MK and to have densities between the upper chromosphere and transition region. Our study showcases the importance of high-resolution magnetograms in revealing the mechanisms that trigger phenomena such as EBs, UV bursts, and surges. This could hold implications for small-scale events similar to those recently reported in the EUV using Solar Orbiter. The finding of temperatures beyond 1 MK in the UV burst plasma strongly suggests that we are examining analogous features. Therefore, we recommend caution when drawing conclusions from full-disk magnetograms that lack the necessary resolution to reveal their true magnetic origin.

Crisis Management Response Strategies of Small-Scale Sport Event Organizations to the Effects of the COVID-19 Pandemic

This study explores the strategies utilized by small-scale sport event organizations to respond to the effects of the COVID-19 pandemic. In doing so, it helps inform future crisis management preparedness in small-scale sport event organizations. Using semi-structured interviews, the crisis management experiences of eight participants from six small-scale UK-based sport event organizations were scrutinized. The interviews focused on a holistic understanding of their pre-, during, and post-pandemic experiences. Three key themes emerged from the data. They were (i) the diversification of revenue streams and reduction of costs; (ii) ensuring a customer centric approach; and (iii) the importance of fostering entrepreneurial and innovative characteristics. The study proposes a framework of effective crisis response strategies to help inform small-scale sport event organizations to better plan, prepare, and prevent future crises. Through the theoretical lens of resilience studies, it advances knowledge on the COVID-19 experiences of small-scale organizations in the events industry.

Validating IMERG data for diurnal rainfall analysis across the Indonesian maritime continent using gauge observations

The availability of surface rainfall data with high spatial-temporal resolution is needed to understand the diurnal rainfall characteristics in the Indonesian Maritime Continent (IMC) to improve the accuracy of weather and climate models in this region. This study validates the accuracy of the Final Run product of IMERG data version 06B (V06B) and version 07A (V07A), which have a resolution of 0.1°–30 min for diurnal rainfall analysis over IMC. Validation was conducted for precipitation amount (PA), precipitation frequency (PF), and precipitation intensity (PI), by recording 302 automatic rain gauges (RG) every 10 min from January 2014 to September 2021. IMERG V06B and V07A perform well in observing diurnal PA and PF but struggle in observing diurnal PI compared to RG observations. This has been determined by the correlation coefficient (CC) values of IMERG V06B (V07) data, which are 0.76 (0.72) for PA, 0.77 (0.76) for PF, and 0.21 (0.13) for PI. The IMERG data align to an extent with RG observations for the PA value, having a small relative bias (RB). The results also display a systematic PF and PI values error. The high false alarm ratio (FAR) of IMERG data suggests rain detection errors, leading to overestimated PF values. Additionally, the underestimation of PI values is due to the limitation of IMERG data in observing extreme and small-scale rain events. About 86.10% (78.14%) and 81.45% (81.78) of IMERG V06B (IMERG V07A) data show a peak time difference of <3h for PA and PF when compared with RG observations. Overall, IMERG V06B performs better than V07, possibly due to inaccurate orbits of GPROF data, removal of SAPHIR satellite observations, and inter-calibration issues with CORRA and GPCP data. Continuous monitoring and data improvements are necessary to improve the accuracy and reliability of IMERG data in detecting diurnal rainfall patterns in the IMC region.

Assessing the impact and resilience of the community in the aftermath of a small-scale tornado: A field survey-based analysis

Extreme weather can lead to the formation of small-scale tornadoes. Tornadoes are generated by cumulonimbus clouds resulting from convection or orographic lifting of an unstable air mass interacting with a relatively warm air mass within a frontal boundary. The village of Donohudan experienced a small-scale tornado event that resulted in damage to buildings, yards, power infrastructure, and injuries to individuals. This was the first time the community faced a small-scale tornado event, leading to a lack of understanding in handling the aftermath. The aim of this research is to analyze the impact of and resilience to small-scale tornadoes among the population. The research methodology involves field surveys to determine the extent of damage based on the Beaufort scale. The Connor Davidson Resilience Scale (CD-RISC) is employed as a measurement criterion to assess community resilience. The predominant damages were light structural damages and flying roofs caused by the small-scale tornado. Donohudan village demonstrated a moderate level of resilience to small-scale tornadoes, influenced by factors such as flexibility in adapting to changes and challenges, support from family and social networks, spiritual influence, and having a goal-oriented life.

Persistent Homology Analysis for Solar Magnetograms

Understanding the magnetic fields of the Sun is essential for unraveling the underlying mechanisms driving solar activity. Integrating topological data analysis techniques into these investigations can provide valuable insights into the intricate structures of magnetic fields, enhancing our comprehension of solar activity and its implications. In this study, we explore what persistent homology can offer in the analysis of solar magnetograms, with the objective of introducing a novel tool that will serve as the foundation for further studies of magnetic structures at the solar surface. By combining various filtration methods of the persistent homology analysis, we conduct an analysis of solar magnetograms that captures the broad magnetic scene, involving a mixture of positive and negative polarities. This analysis is applied to observations of both quiet-Sun and active regions, taken with the Hinode/Solar Optical Telescope and SDO/Helioseismic and Magnetic Imager, respectively. Our primary focus is on analyzing the properties of the spatial structures and features of the magnetic fields identified through these techniques. The results show that persistent diagrams can encode the spatial structural complexity of the magnetic flux of active regions by identifying the isolated, connected, and interacting features. They facilitate the classification of active regions based on their morphology and the detection and quantification of interacting structures of opposing polarities, such as δ spots. The small-scale events in the quiet Sun, such as magnetic flux cancellation and emergence, are also revealed in persistent diagrams and can be studied by observing the evolution of the plots and tracking the relevant features.

Bursting-process modulation in a turbulent boundary layer via the natural visibility graph method

This study proposes a new method for detecting bursting events based on a natural visibility graph and reveals the amplitude modulation of the large-scale to small-scale bursting processes. Through hot-wire measurements of the turbulent boundary layer, velocity signal sequences with different normal heights are obtained. First, a natural visibility graph method is used to map the velocity signal into a visibility network to obtain a time series of the network degree centrality. Next, a statistical analysis of the degree centrality shows that it can reflect hidden structural characteristics. Moreover, the degree centrality signals have a comparable spatial/temporal scale to the Taylor microscale, which indicates that the degree centrality could provide a potential method to characterize the instantaneous wavenumber/frequency information of small-scales. Then, a new method for detecting bursting events is provided based on the degree centrality values. Characterizations of small-scale bursting events are investigated, providing results for the amplitude modulation between large-scale and small-scale bursting processes. These results show that, in the near-wall region, an increase in amplitudes of a small-scale bursting process is induced for intervals of positive large-scale fluctuations and vice versa for negative large-scale fluctuations. The outer zone shows opposite. The phenomenon of temporal shifting of the amplitude modulation is then investigated and shows that the high-speed large-scales lag behind the small-scale bursting process in the near-wall region, while the outer region shows the opposite. The distance of the small-scale bursting processes leading to the large-scales in the near-wall space is log-linear with the wall-normal height.

Microallopatric speciation in the relict dung beetle genus Grebennikovius (Coleoptera: Scarabaeidae) in the Eastern Arc Mountains

Abstract The Eastern Arc Mountains (EAMs) in Tanzania and Kenya are renowned for their exceptional species endemism often restricted to isolated mountain blocks. Forest fragmentation during the Pliocene–Pleistocene played a significant role in shaping the EAMs’ biodiversity by facilitating allopatric speciation between different mountains. However, only a few studies focused on species diversification within the same mountain block. In this article, we investigated the taxonomy and evolution of the dung beetle genus Grebennikovius, endemic to the Uluguru Mountains. Our goal was to unravel factors promoting allopatric speciation within a confined geographic area like the Ulugurus. We used an integrative taxonomic approach, combining phenotypic data and COI barcodes to delimit species and reconstructed a timetree of the genus. Molecular and morphological evidence consistently recovered 4 distinct Grebennikovius species, of which 3 are new to science: G. armiger n. sp., G. basilewskyi (Balthasar, 1960), G. lupanganus n. sp., and G. pafelo n. sp. Grebennikovius represents a rare case of microallopatry, with all species occurring in close proximity within different regions of the limited Uluguru forest (∼230 km2). We infer that speciation was driven by the interplay between climate fluctuations during the Miocene and mid-Pleistocene, Uluguru topography, and the stability of rainforest ecological conditions. The latter factor probably favored the loss of wings and a specialization for Uluguru microhabitats, reinforcing population isolation and divergence. This study highlights a unique instance of diversification resulting from small-scale speciation events, providing valuable insights into the evolution of Eastern African rainforest arthropods and underscoring the importance of microhabitats conservation.

Complex patterning in jerky flow from time series analysis and numerical simulation

The paper is a tribute to Ladislas P Kubin’s long-standing work on the collective behavior of dislocations in jerky flow. In a first part, it reviews his contributions to the statistical, dynamical and multifractal analyses carried out on stress-time series recorded from both single crystals and polycrystalline samples of dilute alloys subjected to tensile tests at constant strain rate. Various spatio-temporal dynamical regimes were found as the applied strain rate was varied. Type C static bands were associated with quasi-random collective behavior, the hopping type B and propagating type A bands could be shown to correspond to chaotic and self-organized critical dynamics, respectively. The crossover between the A and B regimes was characterized by a large spread in the multifractal spectrum of stress drops, associated with heterogeneity of the dynamics. In a second part, the paper reviews the nonlocal models Ladislas inspired to interpret these results from numerical solutions of the boundary value problem, on the basis of dynamic strain aging, the incompatibility stresses associated with dislocations, their plastic relaxation and the spatial couplings they inherently involve. Eventual developments of this research, rooted in the same ideas, on the statistical and multifractal analyses of the accompanying acoustic emission are reviewed and discussed in terms of the synchronization of small-scale plastic events.