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Performance Analysis of the LDPC‐Coded Hybrid L QAM‐MPPM for UWOC Systems
Full text linkThis paper proposes a hybrid optical modulation scheme that integrates spectrally efficient quadrature amplitude modulation (QAM) and power‐efficient multipulse pulse position modulation (MPPM) for underwater wireless optical communication (UWOC) to achieve high spectral and energy efficiencies and combines it with LDPC codes to mitigate the adverse effects imposed by the underwater turbulence channel. Considering the effect of both direct‐current (DC) bias level and modulation index on signal‐to‐noise ratio (SNR), for the first time, an approximate closed‐form bit error rate (BER) expression for the hybrid L‐QAM‐MPPM UWOC system over turbulence channels is derived and verified using Monte Carlo (MC) simulations. Subsequently, comparisons among the hybrid L‐QAM‐MPPM, conventional MPPM and QAM systems with comparable spectral efficiency for exponentiated Weibull (EW)‐modelled turbulence channel indicate that hybrid modulation offers resilience to turbulence, although the BER in the additive white Gaussian noise (AWGN)‐only channel is higher. Finally, the effectiveness of LDPC codes in improving the performance of hybrid modulations is discussed, with coded 128‐QAM‐(12, 2) MPPM offering ∼6.5 and 5.8 dB code gains at a BER of 10 − 4 in strong and moderate turbulence, respectively. These results demonstrate the promise of hybrid modulation with LDPC as a robust and efficient modulation scheme for UWOC systems
Tunable optical lattices for the creation of matter-wave lattice solitons
Full text linkWe present experimental techniques that employ an optical accordion lattice with dynamically tunable spacing to create and study bright matter-wave solitons in optical lattices. The system allows precise control of lattice parameters over a wide range of lattice spacings and depths. We detail calibration methods for the lattice parameters which are adjusted to the varying lattice spacing, and we demonstrate site-resolved atom number preparation via microwave addressing. Lattice solitons are generated through rapid quenches of the atomic interaction strength and the external trapping potential. We systematically optimize the quench parameters, such as duration and final scattering length, to maximize soliton stability. Our results provide insight into nonlinear matter-wave dynamics in discretized systems and establish a versatile platform for the controlled study of lattice solitons
Institutions under pressure : the effect of community groups on forest preservation after a natural disaster
No full textWe analyse the resilience of community-based institutions to large shocks. Our case study is on forest user groups in Nepal in the aftermath of the 2015 earthquake. We combine remote sensing data with detailed administrative data on forest user groups and exploit spatial variation in the intensity of the earthquake. Using a triple difference strategy, we show that the earthquake-induced increase in deforestation is significantly lower in locations with a higher share of forest covered by forest user groups. Thus, these institutions lead to more sustainable use of forests when they are under pressure. Regarding potential mechanisms, survey data suggest that social capital plays a role for the positive effects of forest user groups. More generally, our findings show that shifting governance of local resources to community-based institutions can be an effective policy in times of increased pressure on natural resources
Cognitive and motor behaviors in Alzheimer's, Parkinson's, and healthy individuals during the ViewMind 3-D Task
Full text linkBackground: Oculomotor behaviors linked to cognitive performance can differentiate between the trajectories of neurodegeneration (ND) that lead to Alzheimer's disease (AD) (Fernández (Fernandez et al., 2022) or Parkinson's Disease (PD) (Mosimann et al., 2005). We investigated whether ViewMind technology, which combines Virtual Reality, Hand Movement Sensors (HMS), eye tracking (ET) and 3D Spheres Touching Task (3DT) identifies different cognitive and motor behaviors among symptomatic (AD) and asymptomatic carriers (ASYMPTAD) of the mutation E280A-PSEN1 from Antioquia, Colombia, PD patients (without and with MCI – PDMCI), and Controls (HC). Methods: We recruited 76 ASYMPTAD (age 32.5±8.1), 16 AD (age 66.6±8.5), 45 PD (age 64.5±9.4, 10 PDMCI (age 68.2±9.8) and 62 HC (age 34±10.2). All performed standard neuropsychological tests and the 3DT. The task assesses the ability to detect 3D visual targets (i.e., visual accuracy and reaction time), to track these targets as they move from the background to the subject (i.e., tracking accuracy), and hand movement initiation towards targets (i.e., hand accuracy and reaction time). Results: Tracking accuracy, hand reaction time, and visual reaction time as a function of the number of touched targets were more affected in AD, PD, and PDMCI patients when compared to ASYMPTAD and HC. ASYMPTAD and HC reached the most significant number of targets. Mean tracking accuracy followed the pattern PDMCI > PD > AD > HC & ASYMPTAD (p AD > PD > HC & ASYMPTAD (p PDMCI > PD > HC & ASYMPTAD (p = 0.006). Conclusion: ViewMind's 3DT identifies cognitive and motor profiles across neurodegenerative diseases. Impairments were apparent in and discriminable between clinical groups with (PD) or without (AD) predominant movement disorders and lacking in non-clinical samples (HC & ASYMPTAD). Available assessments cannot identify the interplay of motor and cognitive control during ongoing ecologically valid tasks. This highlights the role of this novel technology in refining theories and applications of visual-motor integration tasks in ND diseases
Affective-reflective pedagogy in the educational process of teaching theoretical disciplines for PETE students : the Ukrainian case
Full text linkBackground The combination of the less common affective approach with the well-known reflective learning in the process of Physical Education Teachers Education (PETE) seems to be a quite acceptable step, both theoretically and practically, to bring the educational process to a more holistic level of functioning, where the motives, interests, and emotional state of students are seriously considered. Purpose The aim of this article is to present the experience of re-professionalising of a teacher of pedagogy to improve the teaching of theoretical disciplines in the PETE programme for Ukrainian students and to outline the idea of affective-reflective pedagogy. Methods This study used a methodological approach – practitioner inquiry, which is aimed at professional development of teacher and improvement of his own practice, as well as the inclusion of reflections and voices of students, which ultimately allowed to present the feasibility of the idea of affective-reflective pedagogy because of combining the affective domain with reflective practices. Results Two themes were developed: 1) rationale for the re-professionalisation of teacher of theoretical disciplines in the PETE programme for Ukrainian students, and 2) evidence of the impact of improved teaching methods for theoretical disciplines on the self-awareness of Ukrainian PETE students as future teachers and their teaching methods. The data obtained during this study from the students indicate that the classes had a strong impact on their affective domain. Some students admitted that the classes allowed them to start living more consciously, learn to truly feel and experience, better understand themselves, experiment with hidden influences, reflect and change, as well as become more flexible in finding result-oriented compromises. Conclusion The example of affective-reflective teaching of a pedagogy course proves that reliance on the affective domain in a reflective environment can influence students' consciousness, evoke in them an inner desire to be active in class and practice transferring the experience of the affective-reflective approach gained in class to their extracurricular life. Impact Statement Affective-reflective pedagogy is an innovative approach that combines the affective domain with reflective practices to organise a successful educational process for PETE students. Tested with Ukrainian PETE students, affective-reflective pedagogy removes the obstacles that have arisen during the traditional teaching of theoretical disciplines
From scenario thinking to scenario doing : strategic management as wayfinding
No full textThis paper blends the ingredients of practice-oriented theorizing, scenarios, and dynamic capability to propose wayfinding as an alternative to strategic management as planning. It will augment the notion of “scenario thinking” by placing it within the “scenario doing” of participating in developmental trajectories by which a firm evolves into the future. Wayfinding is presented as being done by way of practical coping, conscious reflecting, or practical solutioning. A firm engaging in practical coping utilizes practical intelligibility—an understanding or “knowhow” and “know why“ of how to enact practices—to generate a ‘business-as-usual’ trajectory that is reflected in a baseline scenario: a cognitive and discursive representation of how this trajectory moves the firm into the future. A firm experiences a breakdown IN practical coping when a lack of practical intelligibility makes a firm unable to participate in the ‘business-as-usual’ trajectory. Scenario thinking then has to take on the form of conscious reflecting to identify which additional practical intelligibility the firm needs to draw in to restore a firm's practical coping. Practical solutioning deals with a breakdown OF practical coping when practical intelligibility is non-existent and is to be newly created. Scenario thinking thus becomes speculative imagination to develop new practical intelligibility. Dynamic capability then is elaborated as a firm's ability to participate in ongoing developmental trajectories by way of practical coping, conscious reflecting, and practical solutioning. The argumentation is illustrated with the case of how MP3 became part of the recorded music field
Towards a calibration methodology for an in-series phased array ultrasonic inspection of weld cladding at elevated temperatures
Full text linkIn the early 21st century, rising manufacturing costs have incentivised industries to seek innovative solutions for producing high-integrity components more efficiently. One effective strategy is to perform quality inspections, such as Non-Destructive Testing (NDT), during production or in-process, rather than at the end of the process. This approach minimises rework, enhances schedule reliability, and boosts manufacturing throughput. Welding is a commonly used process in the fabrication of high-value and safety components, including nuclear pressure vessels, which are often clad with corrosion-resistant alloys. This cladding provides superior metallurgical properties on the surface while allowing the use of a more cost-effective base material, ultimately reducing overall production costs. Traditional code-compliant ultrasonic inspection methodology requires the calibration of the inspection parameters to known reference reflectors prior to and post inspection within a ± 14 °C tolerance, preventing the accurate inspection of weld cladding methods during manufacture, when temperature variance can often exceed this range. Until now, in-process inspection has not been applied to weld cladding applications with a defined link to a calibration standard. This paper presents a novel approach to optimising ultrasonic in-process inspections by means of compensation strategies to mitigate the negative effects of elevated temperatures and their influence on material velocity and attenuation, manifesting as variation in reference reflector amplitude and sizing. The approach herein demonstrated the ability to effectively compensate for ultrasonic calibration parameters required for the inspection of an Inconel EN82H cladding over a steel substrate
The analysis of a column of the Tomb 7 colonnade at the Tombs of the Kings archeological site : A comparative evaluation of scan-to-FEM methodologies
Full text linkThis research investigates the colonnade of Tomb 7 at the UNESCO World Heritage site of the Tombs of the Kings in Paphos, Cyprus. Specifically, a multi-drum column located at the south-east corner of the tomb is examined from both geometric and structural perspectives. Being the only standing element to support the entablature on that side of the tomb, the column is crucial for maintaining the structural stability of the monument. Numerical structural analyses are performed on the column via the finite element method (FEM), supported by close-range recording techniques—particularly terrestrial laser scanning (TLS)—to generate finite element (FE) models. Several modelling strategies capable of converting point cloud data into reliable structural models are developed and compared with the aim of identifying the most effective and cost-efficient approach. Each method is analyzed in detail to evaluate its workflow, assumptions, strengths, and limitations in the context of heritage structures with complex irregular geometries. Linear static and dynamic analyses are performed on five different FE models to assess the column’s mechanical response and to understand how differences in geometric representation affect the structural behaviour. The results indicate that all approaches adequately capture the general structural response. The comparison of the different modelling strategies highlights the trade-offs between geometric accuracy, computational efficiency, and practical usability. These outcomes indicate the potential and the current limitations of exploiting point cloud data for structural analysis and contribute to the development of more robust and accurate scan-to-FEM methodologies for the conservation and assessment of cultural heritage structures
Suppressing leakage and maintaining robustness in transmon qubits : Signatures of a trade-off relation
Full text linkWe study the problem of optimally generating quantum gates in a logical subspace embedded in a larger Hilbert space, where the dynamics is also affected by unknown static imperfections. This general problem is widespread across various emergent quantum technology architectures. We derive the fidelity susceptibility in the computational subspace as a measure of robustness to perturbations, and define a cost function that quantifies leakage out of the subspace. We tackle both effects using a two-stage optimization where two cost functions are minimized in series. Specifically, we apply this framework to the generation of single-qubit gates in a superconducting transmon system, and find high-fidelity solutions robust to detuning and amplitude errors across various parameter regimes. We also show control pulses which maximize fidelity while minimizing leakage at all times during the evolution. However, finding control solutions that address both effects simultaneously is shown to be much more challenging, indicating the presence of a trade-off relation
Towards autonomous optical camera communications : Light source localisation using deep learning
Full text linkThis research significantly improves the link reliability and robustness of optical camera communications (OCC) by leveraging deep learning for light source modulation filtering, reflection filtering, and precise light source localisation. By using image sensors as receivers in OCC, data transmission is not only enabled, but other applications are also facilitated, such as detecting objects and humans, making OCC highly attractive in healthcare, intelligent transport systems, and indoor positioning. However, the position of the desired signal in the received image frame must be tracked in dynamic scenarios (i.e., nonstationary applications), in order to maintain the communication link. Moreover, as sixth-generation (6G) wireless networks envision highly autonomous systems that rely on seamless integration of communication and sensing, deep learning is key to enabling robust and adaptive light source localisation and sensing in OCC, which enables vision-based autonomy in dynamic environments. It should be noted that a deep learning-based approach provides more accuracy even when there are multiple noise sources in the environment, reflections, and complex backgrounds, and under mobility conditions, in which traditional light source detection/tracking methods are not effective. Hence this study investigates the use of a deep learning-based approach by analysing the detection accuracy under different configurations and unseen images. The results obtained demonstrate consistently high detection performance with average precision (at an intersection-over-union threshold of 0.70 of 0.84 to 0.97. These results pave the way for autonomous receivers that will be able to select signals intelligently and decode them
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