28579 research outputs found
Sort by
On the behavior of Linear Dependence, Smaller, and Generalized Alignment Indices in discrete and continuous chaotic systems
No full textThe discrimination between order and chaos in dynamical systems remains a central problem in the field. Among the most widely used indicators are the Smaller Alignment Index (SALI), the Generalized Alignment Index (GALI), and the Linear Dependence Index (LDI), all of which exploit the evolution of deviation vectors to distinguish regular from chaotic motion. In this paper, we first show analytically, and confirm numerically, that the decay rates of LDI for chaotic orbits in both discrete- and continuous-time systems are the same with those of GALI reported in the literature. Our derivations, however, are more accessible, relying on the Singular Value Decomposition rather than the wedge-product formulation of GALI, which involves volumes of higher-dimensional parallelepipeds. We then derive the analytical expression for the decay rate of SALI in chaotic maps, demonstrating that it depends on the difference of the two largest Lyapunov exponents, as previously established for continuous-time systems. Crucially, we show analytically that the second Lyapunov exponent must always be considered, independent of its sign, in order to capture correctly the decay of SALI. This contrasts with existing results for continuous systems, where the second exponent is greater or equal than zero for chaotic orbits. Our analytical and numerical findings, therefore, extend the SALI decay rate formula to both continuous- and discrete-time systems. Finally, we confirm numerically that the decay rate of the SALI for chaotic maps is accurately described by our formula, which incorporates the two largest Lyapunov exponents, regardless of whether the second exponent is positive, zero, or negative
A Fully Unsupervised Online Classification Algorithm for Event-Related Potential based Brain-Computer Interfaces
Full text linkObjective: Brain-computer interfaces (BCIs) based on event-related potentials (ERPs) are among the most accurate and reliable BCIs. However, current mainstream classification algorithms struggle to eliminate the need for calibration and rely on expensive labeled data, limiting the practical usability of ERP based BCIs. The development of fully unsupervised algorithms is essential for the advancement of practical applications of BCI systems. Methods: In this study, we propose a novel unsupervised classification method called sliding-window distribution distance maximization (sDDM). This algorithm utilizes sliding windows to highlight important temporal features and transforms the metric of inter-class differences from absolute distances to relative distribution distances in Mahalanobis space, while incorporating information on target event similarity from the BCI paradigm. Additionally, our proposed spatial dimensionality reduction strategy ensures smaller spatial dimensions and more prominent spatial features. Results: We compare our proposed method to other state of-the-art unsupervised classification methods and evaluate it offline on our self-collected dataset, a public dataset recorded during the use of a P300 Speller by patients with ALS, and the BCI Competition III Dataset II. Our results demonstrate that our proposed method achieves the best spelling accuracy across all datasets, surpassing other unsupervised algorithms. We further explore its improvement effectiveness through ablation experiments. Conclusion: Our proposed method enhances the performance of unsupervised classification in ERP-based BCIs
Unravelling the interplay between institutional logics, organizational identity, and the embeddedness of MNE subsidiaries in host countries
Full text linkAmid growing scholarly interest in institutional perspectives on MNE subsidiary embeddedness, this study develops a theoretical framework to explain how longstanding MNE subsidiaries navigate competing institutional logics by constructing organizational identities to develop embeddedness strategies in host-country contexts. Drawing on a qualitative case study of a Chinese MNE subsidiary in Ghana, we identify three embeddedness strategies – active engagement, pronounced resistance, and deliberate avoidance – that reflect subsidiaries' ability, willingness and constraints in responding to competing institutional logics. The study contributes to current literature by highlighting how organizational identity serves as a strategic lens for aligning or preserving selected organizational identities and shaping the strategic choices of embeddedness pathways. In particular, we highlight the agentic capabilities of subsidiary managers who, by acknowledging the inevitability of institutional constraints arising from competing institutional logics, adaptively mobilize alternative embeddedness strategies to mitigate and bypass potential institutional frictions
Arterial stiffness adaptations to chronic resistance and aerobic exercise: a systematic review of exercise modalities
Full text linkBackground: Arterial stiffness is a strong predictor of cardiovascular morbidity
and mortality, especially in older adults. Despite exercise being shown to
positively influence arterial health, the relative effectiveness of various exercise
modalities remains unclear.
Objectives: This systematic review aimed to examine the effects of resistance
training (RT), aerobic training (AER), and concurrent aerobic plus resistance
training (CON) on arterial stiffness in older adults, a recognised modifiable and
independent cardiovascular risk factor.
Methods: A comprehensive search of Medline (EBSCO), EMBASE, the Cochrane
Database of Systematic Reviews, and clinicaltrials.gov was conducted. The
robust search strategy, which also included systematic reviews being handsearched
for relevant articles and a forward and backwards citation search
on the included articles, was employed to reduce the risk of selection and
publication biases. Studies included in the review assessed arterial stiffness using
pulse wave velocity (PWV) and focused on individuals aged 60 years and above
who participated in a chronic (≥ 8 weeks) structured exercise intervention (RT,
AER, or CON). Only randomised controlled trials were included. Sixteen studies
met the inclusion criteria, and their methodological quality was evaluated using
the PEDro scale.
Results: The findings indicated that resistance training generally had a neutral
effect (mean difference, MD: 0.06 m/s. SD: ±0.45) on arterial stiffness, whilst
aerobic training produced modest improvements (MD: −0.62 m/s, SD: ±0.51).
Notably, concurrent training consistently reduced arterial stiffness across
diverse older adult(s) populations (MD: −0.85 m/s, SD: ±0.63).
Conclusion: Combined aerobic and resistance training is the most effective
non-pharmacological strategy for reducing arterial stiffness in older adults. This
approach may offer essential benefits for cardiovascular health and healthy ageing. Further long-term studies are needed to explore the mechanisms involved and to inform tailored exercise interventions in geriatric populations
Developing Indian Pasts? The Archaeological Survey of India, 'Postcolonial' Archaeology, and Technical Assistance in Nepal
Full text linkThis article examines archaeological assistance provided to Nepal by the Archaeological Survey of India as part of India’s aid efforts there in the 1960s. It demonstrates how that work, which endeavored to show long-standing Indian-Nepali connections and strengthen the two countries’ contemporary relationship, sat within a complex set of threads tying it to wider interest in the regional past of post-Partition India. Those threads were filtered through the British Raj, European Orientalism, and local responses to it; they were also connected to post-Partition India’s attempts to assert its regional power and the archaeological theorization and materialization of an ‘Indian’ identity. The Indian bureaucracy that helped to link India and Nepal both powered this Indian archaeological work abroad and, at times, proved its undoing. Observing this messy nexus of paperwork and archaeological practice, the article argues for further investigation of the movement and circulation of archaeological knowledge in this critical period in global history: an investigation that will reveal both a more complex picture of how that knowledge has operated ‘in transit’, while deepening understanding of archaeology’s messy coloniality at a time when ethical questions relating to the discipline have come to the fore
How do child & adolescent psychotherapists work with the erotic transference with adolescents?
Full text linkAdolescence is a period of profound psychological and physical transformation, during which early feelings, desires, and conflicts are reactivated. Sexuality plays a central role in this developmental phase, and the emergence of sexual and erotic feelings can be particularly unsettling when they arise within the therapeutic relationship. The phenomenon of erotic transference, the displacement of unconscious sexual and loving feelings onto the therapist, poses distinctive clinical and ethical challenges, yet remains underexplored within child and adolescent psychotherapy (Jackson, 2017; Lena, 2017; Brady, 2018; Davids, 2022). This qualitative study explores how Child and Adolescent Psychotherapists (CAPTs) understand and work with erotic transference in adolescent psychotherapy, the risks and opportunities it presents, and the reasons it continues to be a comparatively under-addressed topic within the profession. Semi-structured interviews were conducted with six qualified CAPTs trained within a Kleinian or post-Kleinian framework. Interviews were transcribed verbatim and analysed using Reflexive Thematic Analysis (Braun & Clarke, 2006, 2019, 2022). Five overarching themes were identified, including one with subthemes. Findings highlight the importance of recognising and giving meaning to sexuality within therapeutic work, attuning to the adolescent’s developmental stage, and maintaining a reflective stance on the therapist’s own countertransference. The study also underscores the personal, institutional, and cultural resistances that can inhibit open engagement with erotic material. Avoidance of these dynamics risks reinforcing shame and limiting the adolescent’s capacity for integration and relational development. The research calls for greater openness and reflection on erotic transference within training, supervision, and clinical discourse, emphasising its developmental and therapeutic significance when handled ethically and thoughtfully. Implications for clinical practice, training, and future research are discussed
Spam Call Detection with Hybrid Call ID Spoofing Detection and Cryptographic User Authentication
Full text linkCaller ID spoofing (CIS) remains a major challenge in combating spam calls, as attackers can generate spam even with seemingly legitimate identifiers. Existing CIS detection (CISD) approaches, whether network-based or device-based, suffer a high false positive ratio and are limited in scalability and effectiveness. This paper proposes a comprehensive spam call detection framework that combines CISD with cryptographic user authentication (UA) to ensure secure verification of authorized callers. We introduce a hybrid CISD method, integrating network- and device-based approaches to exploit their complementarity, and a SMS-based CISD method, SMSpoof. We design a novel receiver-initiated UA scheme, ReCall, which leverages a UA server to validate caller identity and securely bind users to call IDs. By employing CISD and ReCall jointly, the framework achieves both higher detection accuracy and efficiency. Experimental results demonstrate the feasibility and effectiveness of the proposed approach, showing significant improvements in spam detection, communication overhead, and computational efficiency
Extensive photophysiological variation in wild barley is linked to environmental origin.
Full text linkIntraspecific variation between crop wild relatives (CWRs) represents a source of untapped genetic diversity for crop improvement. At the same time, improving photosynthesis in crops has the potential to enhance yield. Thus, exploring variation for photophysiology within CWRs is an important, yet underexplored, research area. We describe a common garden experiment where 320 wild barley accessions were grown across two seasons. A photophysiology phenotyping pipeline was employed to quantify > 30 traits within this diversity panel. Population genetics, genome-wide association analyses (GWAS) and deep phenotyping were performed to address local adaptation hypotheses. Heritable variation was detected across this photophysiological spectrum, with genotype-by-environment (G × E) interactions being prevalent. Evidence for local adaptation was observed in the form of subpopulation differences, signals of selection and allele frequency variation associated with markers identified via GWAS. Phenotyping of representative accessions across distinct water availabilities highlighted a role for stomatal conductance (gs) in adaptation to dry environments. We identified substantial variation in key photosynthesis-associated traits in a CWR closely related to barley, an economically important crop species. Our results demonstrate that this variation is partially due to local adaptation, where plasticity in gs appears important for maintaining photosynthesis and biomass accumulation in water-restricted conditions
Skill formation and the trouble with child noncognitive skill measures
No full textThis paper develops a framework to address issues of contamination in parent-reported measures of child noncognitive skills. We estimate a dynamic model in which child and parental skills evolve jointly and leverage information provided by teachers and interviewers to deal with contamination of parent-reported measures. The model also allows us to examine the relative importance of mothers and fathers in the evolution of child skills. Our findings reveal that ignoring contamination significantly underestimates the role of maternal non-cognitive skills in the evolution of child noncognitive skills. Additionally, we find evidence of stronger feedback effects from child skills to mothers than fathers. Simulation exercises demonstrate how contamination can distort evaluations of early childhood policies, underscoring the importance of robust measurement approaches