Feedback Factor Research Articles

Utilizing four-node tetrahedra-shaped Hopfield neural network configurations in the local magnetization assessment of 3d objects exhibiting hysteresis

There is no doubt that the accurate assessment of local magnetization in three-dimensional objects exhibiting hysteresis is crucial to accurate performance estimation of a variety of electromagnetic devices. Recently, it has been demonstrated that a Stoner-Wohlfarth-like elementary hysteresis operator may be constructed using two-node Hopfield neural network (HNN) having internal positive feedback. Based upon the previously mentioned approach, this paper presents a methodology using which local magnetization in 3D objects exhibiting hysteresis may be assessed. The approach utilizes a four-node tetrahedron-shaped HNN with activation functions constructed using a weighted superposition of a step and sigmoidal functions in accordance with the M − H curve of the material under consideration. In this approach, the internal feedback factors between the different nodes for any tetrahedron are dependent on its geometrical configuration. Hence, shape configuration effects on the magnetization patterns of any three-dimensional object approximated by an ensemble of tetrahedra are implicitly taken into consideration. To demonstrate the applicability of the proposed approach, computations were carried out for different three-dimensional magnetized bodies having different M − H curves. Theoretical and computational details of the approach are given in the paper.

University Students’ Perspectives on Open and Distance Learning (ODL) Implementation Amidst COVID-19

Open and Distance Learning (ODL) has been implemented in universities around the world since decades ago. With COVID-19 pandemic, its implementation has been accelerated globally at an unprecedented speed and haste. Thus, the aim of this paper is to investigate the university students’ perspectives on ODL amidst COVID-19. By using the convenient sampling method, a total of 608 diploma and degree students throughout Malaysia have participated and shared their feedback on ODL implementation. The collected data covered their general feedback and what they enjoyed the most about ODL. Moreover, their recommendations on ODL implementation were analyzed by categorising the responses into different themes. The demographic data was summarized using descriptive analysis. A comparison between the diploma and the degree students’ perspectives is also discussed in the paper. The findings show that most students have positive perceptions on ODL implementation, where positive feedback and fun factors are highlighted by the respondents. Some students indicated that ODL should not be continued in the future semester, due to problems such as poor internet connection, budget constraints and time management issues. Recommendations on improvements for better ODL implementations in the near future are also provided. This study contributes to more effective ODL management by presenting the learners’ perspectives
 
 Keywords: Open and Distance Learning (ODL), Online Learning Platforms, Technology, Teaching and Learning, University Students

Lrp4 in hippocampal astrocytes serves as a negative feedback factor in seizures

BackgroundEpilepsy is characterized by the typical symptom of seizure, and anti-seizure medications are the main therapeutic method in clinical, but the effects of these therapy have not been satisfactory. To find a better treatment, it makes sense to further explore the regulatory mechanisms of seizures at genetic level. Lrp4 regionally expresses in mice hippocampus where is key to limbic epileptogenesis. It is well known that neurons release a high level of glutamate during seizures, and it has been reported that Lrp4 in astrocytes down-regulates glutamate released from neurons. However, it is still unclear whether there is a relationship between Lrp4 expression level and seizures, and whether Lrp4 plays a role in seizures.ResultsWe found that seizures induced by pilocarpine decreased Lrp4 expression level and increased miR-351-5p expression level in mice hippocampus. Glutamate reduced Lrp4 expression and enhanced miR-351-5p expression in cultured hippocampal astrocytes, and these effects can be partially attenuated by AP5. Furthermore, miR-351-5p inhibitor lessened the reduction of Lrp4 expression in glutamate treated hippocampal astrocytes. Local reduction of Lrp4 in hippocampus by sh Lrp4 lentivirus injection in hippocampus increased the threshold of seizures in pilocarpine or pentylenetetrazol (PTZ) injected mice.ConclusionsThese results indicated that high released glutamate induced by seizures down-regulated astrocytic Lrp4 through increasing miR-351-5p in hippocampal astrocytes via activating astrocytic NMDA receptor, and locally reduction of Lrp4 in hippocampus increased the threshold of seizures. Lrp4 in hippocampal astrocytes appears to serve as a negative feedback factor in seizures. This provides a new potential therapeutic target for seizures regulation.

Academic excellence as a determinant of self-confidence among graduates of ODL programs

PurposeThis study envisioned plausible influential factors on service quality and academic excellence relatable to graduate self-confidence in an open distance learning (ODL) outlook. The objective was to expose the moderating role of academic excellence (graduate satisfaction) between service quality and self-confidence (engagement, achievement, loyalty and opportunity, EALO). It was also of interest to explore how, in what routines factors involved interrelated.Design/methodology/approachThis study utilized exploratory design. Qualitatively, service quality included acclimation, advising, module, tutorial, assessment, feedback and referral factors. Service quality led to academic excellence (GPA, study length, relevance and recognition). Besides, academic excellence influenced self-confidence. Quantitatively, service quality, academic excellence and self-confidence were the independent, moderating and dependent variables. Respondents were randomly selected through a survey of eligible Universitas Terbuka alumni.Findings11 hypotheses were assessed under structural-equation modeling (SEM). Responses from 122 out of 500 graduates were completed. Eight hypotheses were validated by the analysis. The tutorial was the most influential factor followed by module, assessment and acclimation; advising, feedback and referral were excluded. Academic excellence also led to self-confidence. The study was able to visualize a substantial role of academic excellence in moderating service quality to EALO. Besides, important-performance analysis and customer-satisfaction index (IPA-CSI) recognized 21 out of 32 attributes as the pillars of academic excellence.Originality/valueThree of the hypotheses were invalidated by the quantitative analysis. Further inquiry with much broader coverage is then required to diminish the variance to finally find the ideal framework.

An evolution of Colpitts VCO for simultaneous optimization of phase noise and FoM in GaAs technologies

This paper presents a novel co-optimization configuration to simultaneously improve phase noise and FoM in order to solve the long-existing issue of excellent phase noise and mediocre FoM in the light of GaAs technologies. Considering traditional GaAs based Colpitts/class-C VCOs, a first step is taken with the introduction of noise shifting structure while a second step is carried out with the presentation of Darlington pair. Afterwards, a detailed outline of pros and cons of five VCO topologies, including Colpitts/class-C/noise shifting (NS) Colpitts/noise shifting class-C/noise shifting Darlington-based (NSDB) class-C VCO, is given in theory and in practice while respective start-up conditions and capacitive feedback factors are derived mathematically. It can be found that iterative phase noise and FoM improvement is achieved in GaAs based VCOs above in a gradual manner. Furthermore, the output power is stabilized with a simple trick of two-stage Darlington-based topology and thus, the power-hungry buffer is avoided. Ultimately, three VCOs out of the five are fabricated in GaAs technologies while their specifications are thoroughly compared with previous research. The fabricated Colpitts VCO demonstrates a frequency tuning range of 3.59–3.69 GHz with a current consumption of 11.2 mA@5 V supply, a phase noise of − 130.1 to − 129.1 dBc/Hz at 1 MHz offset from the carrier and the output power is around − 5 to − 5.1 dBm. The fabricated noise shifting Colpitts VCO demonstrates a frequency tuning range of 3.58–3.67 GHz with a current consumption of 10.8 mA@5 V supply, a phase noise of − 132.4 to − 130.2 dBc/Hz at 1 MHz offset from the carrier and the output power is around − 2.5 to − 3.5 dBm. The fabricated Darlington-based class-C VCO demonstrates a frequency tuning range of 2.76–2.91 GHz with a current consumption of 9.5 mA@5 V supply, a phase noise of − 138.6 to − 135.9 dBc/Hz at 1 MHz offset from the carrier and the output power is around − 3.06 to − 4.18 dBm. To the best of the authors’ expertise, the proposed Darlington-based class-C VCO achieves both exceptional phase noise and FoM, which far outweigh that of existing GaAs ones.

Hydrometeorological sensitivities of net ecosystem carbon dioxide and methane exchange of an Amazonian palm swamp peatland

Tropical peatlands are a major, but understudied, biophysical feedback factor on the atmospheric greenhouse effect. The largest expanses of tropical peatlands are located in lowland areas of Southeast Asia and the Amazon basin. The Loreto Region of Amazonian Peru contains ~63,000 km2 of peatlands. However, little is known about the biogeochemistry of these peatlands, and in particular, the cycling of carbon dioxide (CO2) and methane (CH4), and their responses to hydrometeorological forcings. To address these knowledge gaps, we established an eddy covariance (EC) flux tower in a natural palm (Mauritia flexuosa L.f.) swamp peatland near Iquitos, Peru. Here, we report ecosystem-scale CO2 and CH4 flux observations for this Amazonian palm swamp peatland over a two-year period in relation to hydrometeorological forcings. Seasonal and short-term variations in hydrometeorological forcing had a strong effect on CO2 and CH4 fluxes. High air temperature and vapor pressure deficit (VPD) exerted an important limitation on photosynthesis during the dry season, while latent heat flux appeared to be insensitive to these climate drivers. Evidence from light-response analyses and flux partitioning support that photosynthetic activity was downregulated during dry conditions, while ecosystem respiration (RE) was either inhibited or enhanced depending on water table position. The cumulative net ecosystem CO2 exchange indicated that the peatland was a significant CO2 sink ranging from −465 (−279 to −651) g C m−2 y−1 in 2018 to −462 (−277 to −647) g C m−2 y−1 in 2019. The forest was a CH4 source of 22 (20 to 24) g C m−2 y−1, similar in magnitude to other tropical peatlands and larger than boreal and arctic peatlands. Thus, the annual carbon budget of this Amazonian palm swamp peatland appears to be a major carbon sink under current hydrometeorological conditions.

An Integrated View of Information Feedback, Game Quality, and Autonomous Motivation for Evaluating Game-Based Learning Effectiveness

Critical factors that influence the value of digital game-based learning (DGBL) for enhancing learning effectiveness remain debatable. Based on the self-determination theory (SDT), people can be autonomously motivated to adopt DGBL to enhance learning effectiveness if their basic psychological needs are satisfied. Additionally, studies that simultaneously examine the effects of two critical factors of information feedback and game quality on students’ autonomous motivation and learning effectiveness in DGBL contexts are missing in the literature. This study integrates information feedback, game quality, and SDT to develop a research model for comprehending the effectiveness of DGBL systems. Data collected from 383 respondents was analyzed to validate our research model. The results showed that information feedback, game quality, and autonomous motivation significantly influenced students’ learning effectiveness and their continuance intention to use DGBL systems. Additionally, autonomous motivation indirectly influenced continuance intention via learning effectiveness. Implications for theory and for practice are discussed accordingly.

Cell fate determined by the activation balance between PKR and SPHK1

Double-stranded RNA (dsRNA)-dependent protein kinase R (PKR) activation via autophosphorylation is the central cellular response to stress that promotes cell death or apoptosis. However, the key factors and mechanisms behind the simultaneous activation of pro-survival signaling pathways remain unknown. We have discovered a novel regulatory mechanism for the maintenance of cellular homeostasis that relies on the phosphorylation interplay between sphingosine kinase 1 (SPHK1) and PKR during exogenous stress. We identified SPHK1 as a previously unrecognized PKR substrate. Phosphorylated SPHK1, a central kinase, mediates the activation of PKR-induced pro-survival pathways by the S1P/S1PR1/MAPKs/IKKα signal axis, and antagonizes PKR-mediated endoplasmic reticulum (ER) stress signal transduction under stress conditions. Otherwise, phosphorylated SPHK1 also acts as the negative feedback factor, preferentially binding to the latent form of PKR at the C-terminal kinase motif, inhibiting the homodimerization of PKR, suppressing PKR autophosphorylation, and reducing the signaling strength for cell death and apoptosis. Our results suggest that the balance of the activation levels between PKR and SPHK1, a probable hallmark of homeostasis maintenance, determines cell fate during cellular stress response.

Fast estimation method of feedback factor based on the derivative of the self-mixing signal.

The self-mixing (SM) technique has been a promising optical measurement technique for a few decades. The estimation of the optical feedback factor C is the key to SM displacement measurement with a better resolution than half a wavelength. But this estimation is extremely complex and tricky, and thus leads to its time-consuming nature, which is one of the important causes that increases the cost and labor for the development of a self-mixing sensor. There have been many methods reported for the C estimation, but they are very time consuming, very sensitive to noise, or can only work in a certain feedback regime. This paper presents a novel approach to the C estimation, which is straightforward and can work for all feedback regimes including weak, moderate, and strong. The estimation precision of the proposed method is not only comparable to that of the data fitting technique but also much simpler.

Health Self-Management Applications in the Work Environment: The Effects on Employee Autonomy.

Organizations increasingly use Health Self-Management Applications (HSMAs) that provide feedback information on health-related behaviors to their employees so that they can self-regulate a healthy lifestyle. Building upon Self-Determination Theory, this paper empirically investigates the basic assumption of HSMAs that their self-management feature provides employees with autonomy to self-regulate their health-related behavior. The two-phase experimental study contained a 4-weeks HSMA intervention in a healthcare work environment with a feedback factor (performance vs. developmental) and pretest and posttest measurements of participants' perceived autonomy. Following the experiment, interviews were conducted with users to gain an in-depth understanding of the moderating roles of feedback and BMI (a proxy for health) in the effects of HSMA on perceived autonomy. Findings reveal that the use of an HSMA does not significantly increase perceived autonomy, and may even reduce it under certain conditions. Providing additional developmental feedback generated more positive results than performance feedback alone. Employees with higher BMI perceived a greater loss of autonomy than employees with lower BMI. The reason for this is that higher-BMI employees felt external norms and standards for healthy behavior as more salient and experienced more negative emotions when those norms are not met, thereby making them more aware of their limitations in the pursuit of health goals.

Symmetry breaking-induced state-dependent aging and chimera-like death state

Aging transition refers to the manifestation of the homogeneous steady state beyond a critical ratio of the inactive oscillators in a network of active and inactive oscillators. In contrast, symmetry breaking in coupled dynamical systems always results in heterogeneous states. In this work, surprisingly, we find that the symmetry breaking coupling facilitates the onset of the homogeneous steady state among the population at the critical proportion of the inactive oscillators despite the presence of a large number of the active oscillators. Further, increase in the natural frequency of the oscillation and the number of the inactive oscillators are conducive to the onset of the aging transition. Interestingly, chimera-like death state is observed in the study related to the aging transition for the first time in the literature in addition to the actual chimera death states among the active oscillator for the random initial conditions. The critical curves corresponding to the stability of the aging transition and the chimera-like death states are deduced, which agrees perfectly with the simulation results. Even a feeble decrease in the feedback factor in the coupling destabilizes the stable aging state thereby facilitating the oscillatory state in the entire parameter space despite the presence of a large proportion of the inactive oscillators increasing the robustness of the network against disorders.

High-speed joint estimation of for strong feedback regime with fringe loss

A self-mixing (SM) displacement sensor is very simple and economic in hardware. In order to improve the resolution of the displacement measurement, the optical feedback factor C must be estimated for the phase unwrapping method (PUM). In particular, when the SM sensor operates in a wide range of the C value including the strong feedback regime with fringe loss, the C estimation is necessary even for any consecutive samples based unwrapping (CSU) method or fringe counting method, which does not intrinsically require the C estimation. It is because each fringe of self-mixing signals (SMSs) in such a case does not correspond to the half of the emission wavelength of the laser. The paper proposes a method of the high speed joint estimation of the optical feedback factor and the linewidth enhancement factor in the case of the strong feedback regime with fringe loss, i.e., when C>7.8. Incorporation of the presented approach with those reported by Ri et al. (2020) and Kim (2020) which have presented the immediate C estimation method in a weak regime and a moderate or strong regime without fringe loss, respectively, will give an effective tool to develop a low-cost real-time SM displacement sensor with a better resolution than half-wavelength.

The contextual effect of completion on the effectiveness of performance feedback

This study investigates the varying effect of performance feedback on performance, depending on the task context. Specifically, we analyze the state of completion (of a product or process) as an essential dimension of the task context. Using a laboratory experiment, we predict and find that performance is lower under completion than under non-completion. Further, we predict and find that the effect of performance feedback on performance differs depending on the state of completion. Specifically, performance feedback increases performance under completion. However, on average, performance feedback is ineffective for non-completion. Our results extend research on the interplay between feedback and contextual factors within firms by providing initial evidence of the impact of the state of completion. In addition, our study has important implications for performance feedback design choices.

Factors Influencing the Use of Mobile Learning in Learning at Jordanian Universities from the Point of View of Experts and Students

This Study Aimed to Identify Factors Influencing the Use of Mobile Learning in Instructional in Jordanian Universities from the Point of View of Experts and Students. The Study Followed the Qualitative Curriculum as Required by the Nature of the Study, the Number of Study Members (19) Faculty Members and (25) Students of Bachelor's and Graduate Students from Public and Private Universities for the Academic Year (2019-2018), the Interview Questions were Built to Reveal Obstacles Faced by Jordanian Universities in the Use of Mobile learning in Instructional. The Results of the Study Revealed that the Opening of a Wide Area of Interaction, Participation, Opinion, Feedback, and Faculty Factor in Terms of Directions, and Training Received the Highest Percentage of Factors Influencing the Use of Mobile Learning from the Point of View of Experts, as it Turns out that the Containment of Mobile Learning Devices For a Clear Learning System, the Educational Services Provided such as Content Delivery, Message Sharing, Ideas and Tasks have the Highest Percentage of Factors Influencing the Use of Mobile Learning from the Student's Point of View. The Study also Concluded with the Following Recommendation: to Introduce the Factors Influencing the Use of Mobile Learning in Instructional in Jordanian Universities and to Study them well, to Take into Account them When Using Mobile Learning in Universities. Key Words : Factors Influencing, Mobile Learning, Experts, Jordanian Universities. DOI : 10.7176/JEP/11-16-15 Publication date : June 30th 2020

The Effectiveness of Direct and Indirect Feedback on Learners’ Writing Performance across Different Gender and Cultural Background

The study investigated whether there is any interaction effect or not among gender, learners’ cultural background and types of feedback factors in the population mean of writing accuracy. The 111 participants were the L2 writing learners of the third semester students of English study program of IAIN Palangka Raya. The participants were clustered into three groups consisting of two experimental classes: the first treatment class treated using Direct Feedback (n=38), the second treatment classtreated using Indirect Feedback (n=37), and one control class did got give feedback (n=36). The data were analyzed using a three way ANOVA. The findings revealed that there was a statistically different effect for the types of feedback (F= 100.857, p= 0.000) and gender (F= 26.688; p=0.000) on the learners’ writing accuracy. However, the learners’ cultural background (F= 0.347; p=0.708) did not give effect on the learners’ writing accuracy. On the contrary, the interaction between: gender and types of feedback (F=2.793, p= 0.066)gender and cultural background (F=0.183, p= 0.833); cultural background and types of feedback (F=0.314, p= 0.868); and among gender, cultural background and types of feedback (F=0.807, p= 0.524) did not give significant effect on the learners’ writing accuracy.The findings strengthened the knowledge body by giving a recommendation on how different types of feedback could have different purposes.

A Modified Darlington-Based Class-C VCO With Simultaneous Optimization of Phase Noise/FoM in GaAs Technology

This letter presents a modified Darlington-based (DB) class-C voltage-controlled oscillator (VCO) topology which achieves a cooptimization of phase noise and figure of merit (FoM) in GaAs technology. Both the Darlington pair and noise shifting techniques are introduced to improve the phase noise in class-C VCOs. Balanced and differential architectures are used to absorb the strength of both the Colpitts and class-C VCO topology with a simple trick of two cascaded stages in the VCO core, which elevates the VCO driving capability with no degradation of power efficiency. In addition, the startup conditions and capacitive feedback factors are derived and compared in both mathematical and simulation manners, which proves the superiority of the topology. The proposed VCO is fabricated in a GaAs bipolar high electron mobility transistor (BiHEMT) technology which demonstrates a frequency range of 2.76–2.91 GHz with a current consumption of 9.5 mA at 5 V supply, a phase noise of −138.6 to −135.9 dBc/Hz at 1 MHz offset from the carrier, an output power of −3.06 to −4.18 dBm, and a peak FoM of −191.2 dBc/Hz at 1 MHz offset. To the best of the authors’ expertise, the proposed DB class-C VCO achieves both exceptional phase noise and FoM, which far outweigh that of the existing GaAs.

Mentor Teachers' Mentoring Practices in Science Teaching: Views of Pre-service Early Childhood Teachers

Practical experiences in teaching settings are an important component of pre-service teacher education programs. Pre-service teachers advance what they learn and improve their science teaching (ST) skills as well as other subjects in early childhood education for the period of teaching practices. In addition, teaching science in early childhood education requires more practices for improving teaching skills. Mentor teacher (classroom teacher) is valuable as well as professors in teacher education programs to pre-service teachers while teaching science. The purpose of this study is to reveal mentor teachers’ mentoring practices in ST according to pre-service early childhood teachers’ views. The method employed method was descriptive study. The sample is composed of 96 pre-service early childhood teachers and their mentors (N=41). Data were collecting within MEST survey. The results showed that most of the pre-service teachers reported their mentor teachers demonstrated less mentoring practices on the system requirement about ST. The pre-service teachers also pointed out that their mentor teachers mostly showed mentoring practices on personal attributes, pedagogical knowledge, modeling, and feedback factors. Knowing and 7understanding the mentoring skills of early childhood teachers in system requirement, pedagogical knowledge, modeling, giving feedback, and personal attributes would have an important growing on preservice early childhood teachers science teaching skills. That will be helpful for shaping new teaching practices and field experiences in different majors for improving teachers teaching skills.

Immediate estimation of feedback factor and linewidth enhancement factor from measured self-mixing signals under moderate or strong regime

The estimation of self-mixing interferometry (SMI) parameters such as optical feedback factor C and linewidth enhancement factor is essential to self-mixing (SM) displacement sensors with sub-wavelength resolution. We propose a new method, which is a very simple and fast method to estimate C and when C > 1 based on an analysis of self-mixing signals (SMSs) in a laser diode. The proposed method is extremely simple, because it takes advantage of analytic relations which enable one to obtain C and from the simple algebraic operations of the data from SMSs. The simplicity of the method is a great help to developing a compact and low-cost self-mixing (SM) displacement sensor with sub-wavelength resolution which cannot ensure complex operation such as optimization. And the proposed method is highly effective in developing real-time and fast algorithm for the C estimation. This method is applicable when the sensor operates under a moderate or strong feedback regime. The estimation accuracy of C and are comparable to the results of Yu et al 2004 IEEE Photon. Technol. Lett. 16 990–2; Zabit 2010 PhD Thesis Toulouse; and Fan 2011 MS Thesis University of Wollongong, respectively, and the estimation time of the C parameter is over 30 times faster than Zabit and Fan.

The Effect of External Attentional Focus and Self-Controlled Feedback on Motor Learning in Older Adults

Abstract Introduction. External focus instruction and self-controlled feedback have beneficial effects on motor learning. The purpose of the present study was to investigate the benefits of combined effects of external focus instruction and self-controlled feedback on balance performance in older adults. Material and Methods. Forty older adults (mean age: 63.21 ± 3.6 years; all female) were selected and randomly divided into 4 groups: self-controlled feedback, external attention, external attention/self-controlled feedback and control group. The task of standing on the platform of the stabilometer device and trying to keep the platform horizontally as much as possible was performed in each 30-sec. trial. The participants of self-controlled group received feedback on the timing of balance after the trials. In the external focus of attention, participants noticed the signs that were located horizontally ahead of their feet. The test was conducted in two sessions. In the acquisition phase, 10 trials of 30 seconds were performed and the retention test was completed 24 hours later as 5 trials of 30 seconds. Results. The results of mixed ANOVA on time data as an indicator of balance in the acquisition phase showed that the mixed group of external focus of attention and self-controlled feedback had better performance than the other groups (p = 0.004). In the retention test, the results of mixed ANOVA showed that the participants in the combined group of external focus and self-controlled feedback had better performance than the other groups (p = 0.006). The external focus of attention and self-controlled feedback performed similarly, and both were superior to the control group (p < 0.05). Conclusions. The results of this study, supporting the OPTIMAL theory of motor learning in the elderly, showed that the combination of two factors of external focus and self-controlled feedback has a double advantage over the presence of each of the factors. Therefore, it is suggested that the combinations of external focus instructions and self-controlled feedback should be used to improve performance and motor learning in the classes of practical and clinical rehabilitation fields.

Particle acceleration in coalescent and squashed magnetic islands

Aims.Particles are known to have efficient acceleration in reconnecting current sheets with multiple magnetic islands that are formed during a reconnection process. Using the test-particle approach, the recent investigation of particle dynamics in 3D magnetic islands, or current sheets with multiple X- and O-null points revealed that the particle energy gains are higher in squashed magnetic islands than in coalescent ones. However, this approach did not factor in the ambient plasma feedback to the presence of accelerated particles, which affects their distributions within the acceleration region.Methods.In the current paper, we use the particle-in-cell (PIC) approach to investigate further particle acceleration in 3D Harris-type reconnecting current sheets with coalescent (merging) and squashed (contracting) magnetic islands with different magnetic field topologies, ambient densities ranging between 108 − 1012m−3, proton-to-electron mass ratios, and island aspect ratios.Results.In current sheets with single or multiple X-nullpoints, accelerated particles of opposite charges are separated and ejected into the opposite semiplanes from the current sheet midplane, generating a strong polarisation electric field across a current sheet. Particles of the same charge form two populations: transit and bounced particles, each with very different energy and asymmetric pitch-angle distributions, which can be distinguished from observations. In some cases, the difference in energy gains by transit and bounced particles leads to turbulence generated by Buneman instability. In magnetic island topology, the different reconnection electric fields in squashed and coalescent islands impose different particle drift motions. This makes particle acceleration more efficient in squashed magnetic islands than in coalescent ones. The spectral indices of electron energy spectra are ∼ − 4.2 for coalescent and ∼ − 4.0 for squashed islands, which are lower than reported from the test-particle approach. The particles accelerated in magnetic islands are found trapped in the midplane of squashed islands, and shifted as clouds towards the X-nullpoints in coalescent ones.Conclusions.In reconnecting current sheets with multiple X- and O-nullpoints, particles are found accelerated on a much shorter spatial scale and gaining higher energies than near a single X-nullpoint. The distinct density and pitch-angle distributions of particles with high and low energy detected with the PIC approach can help to distinguish the observational features of accelerated particles.