Modulator Of Activity Research Articles

Pan-cancer secreted proteome and skeletal muscle regulation: insight from a proteogenomic data-driven knowledge base.

Large-scale, pan-cancer analysis is enabled by data driven knowledge bases that link tumor molecular profiles with phenotypes. A debilitating cancer-related phenotype is skeletal muscle loss, or cachexia, which occurs partly from tumor products secreted into circulation. Using the LinkedOmicsKB knowledge base assembled from the Clinical Proteomics Tumor Analysis Consortium proteogenomic analysis, along with catalogs of human secretome proteins, ligand-receptor pairs and molecular signatures, we sought to identify candidate pan-cancer proteins secreted to blood that could regulate skeletal muscle phenotypes in multiple solid cancers. Tumor proteins having significant pan-cancer associations with muscle were referenced against secretome proteins secreted to blood from the Human Protein Atlas, then verified as increased in paired tumor vs. normal tissues in pan-cancer manner. This workflow revealed seven secreted proteins from cancers afflicting kidneys, head and neck, lungs and pancreas that classified as protein-binding activity modulator, extracellular matrix protein or intercellular signaling molecule. Concordance of these biomarkers with validated molecular signatures of cachexia and senescence supported relevance to muscle and cachexia disease biology, and high tumor expression of the biomarker set associated with lower overall survival. In this article, we discuss avenues by which skeletal muscle and cachexia may be regulated by these candidate pan-cancer proteins secreted to blood, and conceptualize a strategy that considers them collectively as a biomarker signature with potential for refinement by data analytics and radiogenomics for predictive testing of future risk in a non-invasive, blood-based panel amenable to broad uptake and early management.

Research on Small-Target Detection of Flax Pests and Diseases in Natural Environment by Integrating Similarity-Aware Activation Module and Bidirectional Feature Pyramid Network Module Features

In the detection of the pests and diseases of flax, early wilt disease is elusive, yellow leaf disease symptoms are easily confusing, and pest detection is hampered by issues such as diversity in species, difficulty in detection, and technological bottlenecks, posing significant challenges to detection efforts. To address these issues, this paper proposes a flax pest and disease detection method based on an improved YOLOv8n model. To enhance the detection accuracy and generalization capability of the model, this paper first employs the Albumentations library for data augmentation, which strengthens the model’s adaptability to complex environments by enriching the diversity of training samples. Secondly, in terms of model architecture, a Bidirectional Feature Pyramid Network (BiFPN) module is introduced to replace the original feature extraction network. Through bidirectional multi-scale feature fusion, the model’s ability to distinguish pests and diseases with similar features and large scale differences is effectively improved. Meanwhile, the integration of the SimAM attention mechanism enables the model to learn information from three-dimensional channels, enhancing its perception of pest and disease features. Additionally, this paper adopts the EIOU loss function to further optimize the model’s bounding box regression, reducing the distortion of bounding boxes caused by high sample variability. The experimental results demonstrate that the improved model achieves a significant detection performance on the flax pest and disease dataset, with notable improvements in the detection accuracy and mean average precision compared to the original YOLOv8n model. Finally, this paper proposes a YOLOv8n model with a four-headed detection design, which significantly enhances the detection capability for small targets such as pests and diseases with a size of 4 × 4 pixels or larger by introducing new detection heads and optimizing feature extraction. This method not only improves the detection accuracy for flax pests and diseases but also maintains a high computational efficiency, providing effective technical support for the rapid and precise detection of flax pests and diseases and possessing an important practical application value.

All-optical perception based on partially coherent optical neural networks

In the field of image processing, optical neural networks offer advantages such as high speed, high throughput, and low energy consumption. However, most existing coherent optical neural networks (CONN) rely on coherent light sources to establish transmission models. The use of laser inputs and electro-optic modulation devices at the front end of these neural networks diminishes their computational capability and energy efficiency, thereby limiting their practical applications in object detection tasks. This paper proposes a partially coherent optical neural network (PCONN) transmission model based on mutual intensity modulation. This model does not depend on coherent light source inputs or active electro-optic modulation devices, allowing it to directly compute and infer using natural light after simple filtering, thus achieving full optical perception from light signal acquisition to computation and inference. Simulation results indicate that the model achieves a highest classification accuracy of 96.80% and 86.77% on the MNIST and Fashion-MNIST datasets, respectively. In a binary classification simulation test based on the ISDD segmentation dataset, the model attained an accuracy of 94.69%. It is estimated that this system’s computational inference speed for object detection tasks is 100 times faster than that of traditional CONN, with energy efficiency approximately 50 times greater. In summary, our proposed PCONN model addresses the limitations of conventional optical neural networks in coherent light environments and is anticipated to find applications in practical object detection scenarios.

Girolline is a sequence context-selective modulator of eIF5A activity

Natural products have a long history of providing probes into protein biosynthesis, with many of these compounds serving as therapeutics. The marine natural product girolline has been described as an inhibitor of protein synthesis. Its precise mechanism of action, however, has remained unknown. The data we present here suggests that girolline is a sequence-selective modulator of translation factor eIF5A. Girolline interferes with ribosome-eIF5A interaction and induces ribosome stalling where translational progress is impeded, including on AAA-encoded lysine. Our data furthermore indicate that eIF5A plays a physiological role in ribosome-associated quality control and in maintaining the efficiency of translational progress. Girolline helped to deepen our understanding of the interplay between protein production and quality control in a physiological setting and offers a potent chemical tool to selectively modulate gene expression.

Characterization and modulation of human insulin degrading enzyme conformational dynamics to control enzyme activity.

Insulin degrading enzyme (IDE) is a dimeric 110 kDa M16A zinc metalloprotease that degrades amyloidogenic peptides diverse in shape and sequence, including insulin, amylin, and amyloid-β, to prevent toxic amyloid fibril formation. IDE has a hollow catalytic chamber formed by four homologous subdomains organized into two ~55 kDa N- and C- domains (IDE-N and IDE-C, respectively), in which peptides bind, unfold, and are repositioned for proteolysis. IDE is known to transition between a closed state, poised for catalysis, and an open state, able to release cleavage products and bind new substrate. Here, we present five cryoEM structures of the IDE dimer at 3.0-4.1 Å resolution, obtained in the presence of a sub-saturating concentration of insulin. Analysis of the heterogeneity within the particle populations comprising these structures combined with all-atom molecular dynamics (MD) simulations permitted a comprehensive characterization of IDE conformational dynamics. Our analysis identified the structural basis and key residues for these dynamics that were not revealed by IDE static structures. Notably arginine-668 serves as a molecular latch mediating the open-close transition and facilitates key protein motions through charge-swapping interactions at the IDE-N/C interface. Our size-exclusion chromatography-coupled small-angle X-ray scattering and enzymatic assays of an arginine-668 to alanine mutant indicate a profound alteration of conformational dynamics and catalytic activity. Taken together, this work highlights the power of integrating experimental and computational methodologies to understand protein dynamics, offers the molecular basis of unfoldase activity of IDE, and provides a new path forward towards the development of substrate-specific modulators of IDE activity.

Biologically-targeted discovery-replication scan identifies G×G interaction in relation to risk of Barrett's esophagus and esophageal adenocarcinoma.

Inherited genetics represents an important contributor to risk of esophageal adenocarcinoma (EAC), and its precursor Barrett's esophagus (BE). Genome-wide association studies have identified ∼30 susceptibility variants for BE/EAC, yet genetic interactions remain unexamined. To address challenges in large-scale G×G scans, we combined knowledge-guided filtering and machine learning approaches, focusing on genes with (A) known/plausible links to BE/EAC pathogenesis (n=493) or (B) prior evidence of biological interactions (n=4,196). ∼75 x 106 SNP×SNP interactions were screened via hierarchical group lasso (glinternet) using BEACON GWAS data. The top ∼2000 interactions retained in each scan were prioritized using P values from single logistic models. Identical scans were repeated among males only (78%), with two independent GWAS datasets used for replication. In overall and male-specific primary replications, 11 of 187 and 20 of 191 interactions satisfied P<0.05, respectively. The strongest evidence for secondary replication was for rs17744726×rs3217992 among males, with consistent directionality across all cohorts (Pmeta=2.19×10-8); rs3217992 "T" was associated with reduced risk only in individuals homozygous for rs17744726 "G". Rs3217992 maps to the CDKN2B 3'UTR and reportedly disrupts microRNA-mediated repression. Rs17744726 maps to an intronic enhancer region in BLK. Through in-silico prioritization and experimental validation, we identified a nearby proxy variant (rs4841556) as a functional modulator of enhancer activity. Enhancer-gene mapping and eQTLs implicated BLK and FAM167A as targets. The first systematic G×G investigation in BE/EAC, this study uncovers differential risk associations for CDKN2B variation by BLK genotype, suggesting novel biological dependency between two risk loci encoding key mediators of tumor suppression and inflammation.

Truncated TrkB: The predominant TrkB Isoform in Nociceptors.

Truncated TrkB (TrkBT1), traditionally considered a dominant-negative regulator of full-length TrkB (TrkBTK+), remains poorly understood in peripheral sensory neurons, particularly nociceptors. Furthermore, sensory neuronal TrkB expression and function has been traditionally associated with non-nociceptive neurons, particularly Aδ low-threshold mechanoreceptors. This study challenges prevailing assumptions by demonstrating that TrkBT1 is the predominant TrkB isoform expressed in sensory neurons and plays a functional role in modulating neuronal activity. We demonstrate that TrkBT1 is the predominant isoform expressed in nociceptors, identified by markers such as TRPV1, TRPA1, TRPM8 and 5HT3A, as well as non-nociceptors, while the full-length isoform (TrkBTK+) is restricted to non-nociceptive subpopulation. Functionally, we show that acute application of BDNF induces modest calcium influx in nociceptors and prolonged BDNF exposure significantly potentiates capsaicin-induced calcium influx, an effect blocked by the TrkB-specific antagonist ANA12. Additionally, BDNF also promotes the survival of both nociceptive and non-nociceptive neurons in culture, an effect dependent on TrkBT1 activity. Our data also reveal that ANA12 inhibits BDNF-mediated neuronal sensitization and survival in a concentration-dependent manner, implicating distinct TrkBT1 signaling pathways in these processes. Collectively, our findings redefine TrkBT1 as a functional modulator of nociceptor activity rather than a passive regulator of full-length TrkB. By uncovering its dual roles in nociceptor sensitization and survival, this study provides new insights into the molecular mechanisms of BDNF/TrkB signaling in pain. Future work evaluating the role of TrkBT1 in sensory biology could offer new perspectives on how this receptor contributes to neuronal function and plasticity during chronic pain conditions.

Multiple Binding Modes of Inhibitors to Human Carbonic Anhydrases: An Update on the Design of Isoform-Specific Modulators of Activity.

Human carbonic anhydrases (hCAs) are widespread zinc enzymes that catalyze the hydration of CO2 to bicarbonate and a proton. Currently, 15 isoforms have been identified, of which only 12 are catalytically active. Given their involvement in numerous physiological and pathological processes, hCAs are recognized therapeutic targets for the development of inhibitors with biomedical applications. However, despite massive development efforts, very few of the presently available hCA inhibitors show selectivity for a specific isoform. X-ray crystallography is a very useful tool for the rational drug design of enzyme inhibitors. In 2012 we published in Chemical Reviews a highly cited review on hCA family (Alterio, V. et al. Chem Rev. 2012, 112, 4421-4468), analyzing about 300 crystallographic structures of hCA/inhibitor complexes and describing the different CA inhibition mechanisms existing up to that date. However, in the period 2012-2023, almost 700 new hCA/inhibitor complex structures have been deposited in the PDB and a large number of new inhibitor classes have been discovered. Based on these considerations, the aim of this Review is to give a comprehensive update of the structural aspects of hCA/inhibitor interactions covering the period 2012-2023 and to recapitulate how this information can be used for the rational design of more selective versions of such inhibitors.

Distinct mechanisms drive divergent phenotypes in hypertrophic and dilated cardiomyopathy associated TPM1 variants.

Hypertrophic and dilated cardiomyopathies (HCM and DCM, respectively) are inherited disorders that may be caused by mutations to the same sarcomeric protein but have completely different clinical phenotypes. The precise mechanisms by which point mutations within the same gene bring about phenotypic diversity remain unclear. Our objective has been to develop a mechanistic explanation of diverging phenotypes in two TPM1 mutations, E62Q (HCM) and E54K (DCM). Drawing on data from the literature and experiments with stem cell-derived cardiomyocytes expressing the TPM1 mutations of interest, we constructed computational simulations that provide plausible explanations of the distinct muscle contractility caused by each variant. In E62Q, increased calcium sensitivity and hypercontractility was explained most accurately by a reduction in effective molecular stiffness of tropomyosin and alterations in its interactions with the actin thin filament that favor the 'closed' regulatory state. By contrast, the E54K mutation appeared to act via long-range allosteric interactions to increase the association rate of the C-terminal troponin I mobile domain to tropomyosin/actin. These mutation-linked molecular events produced diverging alterations in gene expression that can be observed in human engineered heart tissues. Modulators of myosin activity confirmed our proposed mechanisms by rescuing normal contractile behavior in accordance with predictions.

Kanamycin and G-Quadruplexes: An Exploration of Binding Interactions.

G-quadruplexes (G4s) are distinctive four-stranded nucleic acid structures formed by guanine-rich sequences, making them attractive targets for drug repurposing efforts. Modulating their stability and function holds promise for treating diseases like cancer. To identify potential drug candidates capable of interacting with these complex DNA formations, docking studies and molecular dynamics (MDs) simulations were conducted. Our analysis revealed kanamycin's ability to bind to various G4 structures, offering valuable insights into its potential as a modulator of G4 activity. Kanamycin exhibited favorable interactions with both parallel and hybrid G4 topologies in human structures, suggesting a broader mechanism of action for aminoglycosides. These findings may also shed light on aminoglycoside-associated toxicities, indicating that their effects might extend to binding non-ribosomal RNA structures. In summary, this research highlights kanamycin's potential as a promising tool for influencing G4 dynamics, paving the way for innovative therapeutic strategies targeting G4-related pathways.

Transcriptomic profiling of "brain-eating amoeba" Naegleria fowleri infection in mice: the host and the protozoa perspectives.

The free-living amoeba Naegleria fowleri (NF) causes a rare but lethal parasitic meningoencephalitis (PAM) in humans. Currently, this disease lacks effective treatments and the specific molecular mechanisms that govern NF pathogenesis and host brain response remain unknown. To address some of these issues, we sought to explore naturally existing virulence diversity within environmental NF isolates. Herein, we purified two new NF environmental isolates (NF45 and NF1) and tested their in vivo virulence using experimental infection in mice. We found that NF45 was highly virulent (NF45_HV) compared with NF1 (low virulence, NF1_LV), based on in vivo amoeba growth kinetics and mouse survival. To identify underlying differences, we conducted RNA-seq and bioinformatics analyses from the infected mouse brains. Our results showed that NF1_LV and NF45_HV modulated the expression of their genes during mouse brain infection. Differentially expressed genes (DEGs) in NF1_LV were mostly involved in Translational protein, Protein-binding activity modulator, Protein modifying enzyme, while DEGs in NF45_HV were related to DNA metabolism, Cytoskeletal protein, Protein-binding activity modulator. Proteases (namely the virulence factor Cathepsin B) were upregulated in NF1_LV, while downregulated in NF45_HV. When analyzing the host response against infection by these two NF strains, enrichment analyses uncovered genes and mechanisms related to the host immune responses and nervous systems. We detected more DEGs in NF1_LV infected mice compared to NF45_HV, related to blood brain barrier leakage, immune cell recruitment, cytokine production (including IL-6, IFN-Ɣ and TNFα), inflammation of astrocytes and microglia, and oligodendrocyte and neurons degeneration. Increased expression of neuromotor-related genes such as Adam22, Cacnb4 and Zic1 (activated by NF1_LV infection) and ChAt (activated by NF45_LV infection) could explain PAM symptoms such as muscle weakness and seizures. Globally, our results showed that NF isolated from the environment can have different levels of virulence and differentially modulate their gene expression during brain infection. We also provided, for the first time, a comprehensive information for the molecular mechanisms of neuro-immune and host-pathogen interactions during PAM disease. As the host and the protozoa are strongly implicated in PAM lethality, new therapies targeting both the parasite, and the host should be considered to treat PAM infection.

MINDS OF THE FUTURE: ENTREPRENEURIAL, INNOVATIVE AND TECHNOLOGICAL EDUCATION

This article presents partial results of a Brazilian entrepreneurial education project named Minds of the Future. This project is aimed at low-income high school students from public schools in the city of Juiz de Fora, Minas Gerais State, Brazil. Developed through a collaboration between Federal University of Juiz de Fora and Minas Gerais Education Department, the project aims to contribute for a transformative education, focused on training young people to cope with new life realities, social relationships, and work through the stimulation of critical, creative, technological and entrepreneurial thinking. This project is justified both by the need for young people's engagement in the rapid advances in systems and data automation and by the educational reality of the country, which has a high dropout rate during the transition between elementary and high school.The proposed approach to knowledge transfer and sharing is STEAM. In the first stage, Lego® Education robotics materials were used, which combine Lego® construction elements and intuitive programming language in a 12-hour module of lessons and playful activities offered to 135 students distributed in eight classes during 2024. This and other modules involving 3D modeling, soft skills, financial education and sustainable development will be offered in the second semester of 2024. The project includes professors from different areas and 14 scholarship holders from different undergraduate courses at the Federal University of Juiz de Fora - physics, engineering, computer science, business administration, accounting, law, nutrition and pedagogy - who acted as facilitators during the classes and activities developed. To evaluate the results of this initial experience with the application of the Lego programming and robotics module, a qualitative and quantitative research was conducted. Questionnaires with objective questions were administered to the students via Google Forms at the beginning of the first class and at the end of the last class of the module. Additionally, questionnaires with both objective and open-ended questions were given to the project scholarship holders. Minds of the Future project demonstrated significant positive impacts both among the students and the participating scholarship holders perceptions and skills. The results indicate improvements in various dimensions, from the relationship with teachers to the development of technical skills and increased interest in technology and innovation.

Dantrolene inhibition of ryanodine receptor 1 carrying the severe malignant hyperthermia mutation Y522S visualized by cryo-EM.

Mutations in the skeletal isoform of the ryanodine receptor 1 (RyR1) pose grave risks during anesthesia or treatment with succinylcholine muscle relaxants. These can trigger a potentially lethal malignant hyperthermia (MH) episode via intracellular calcium increase mainly from RyR1 channel leakage. Dantrolene is the only known treatment option to prevent death. The main target of dantrolene is RyR1; however, little is known about the mechanism of inhibition. Cryoelectron microscopy (cryo-EM) structures of dantrolene bound to the severe MH Y522S RyR1 mutant in the closed and open states at 2.5-3.3Å resolution revealed that the drug binds to the channel's cytoplasmic assembly, far from the ion gate, interacting with residues W882, W996, and R1000 in the P1 domain. The finding was validated by Ca2+ imaging and [3H]ryanodine binding in wild-type (WT) and alanine mutants. Dantrolene reduced channel opening probability by restricting the central activation module, "cooling down" the primed conformation caused by the mutation.

Dual-band circular dichroism in chiral metamaterial absorber based on vanadium dioxide

Abstract Chiral metamaterial absorbers are instrumental in a wide array of applications, encompassing multifaceted optoelectronic devices, information-encrypting metamaterials, and thermal-controlled imaging and detection systems. In this study, we showcase a Ꞩ-shaped chiral metamaterial integrated with a vanadium dioxide substrate, which enables dynamic tuning of terahertz (THz) dual-band circular dichroism (CD). This absorber boasts spin-selective absorption, stemming from the selective excitation of the plasmon polaron mode on its horizontal microrod. Notably, right-handed circularly polarized light (CPL) experiences near-perfect absorption at resonance, whereas left-handed circular polarization is absorbed to a much lesser degree, yielding pronounced CD. This exceptional chiral selectivity facilitates dual-band CD effects, with peak values reaching 0.814 and 0.784. Furthermore, by manipulating the conductivity of vanadium dioxide, we can dynamically adjust both the CD and absorption peaks of the chiral metamaterial. The maximum modulation depth of the CD response can attain values as high as 0.807 and 0.776. Our work presents a novel design strategy for the active control and modulation of CPL, thereby expanding the horizons of metamaterial absorber applications within the THz spectrum.

Mitigating Winner-Take-All Resource Competition through Antithetic Control Mechanism.

Competition among genes for limited transcriptional and translational resources impairs the functionality and modularity of synthetic gene circuits. Traditional control mechanisms, such as feedforward and negative feedback loops, have been proposed to alleviate these challenges, but they often focus on individual modules or inadvertently increase the burden on the system. In this study, we introduce three novel multimodule control strategies─local regulation, global regulation, and negatively competitive regulation (NCR)─that employ an antithetic regulatory mechanism to mitigate resource competition. Our systematic analysis reveals that while all three control mechanisms can alleviate resource competition to some extent, the NCR controller consistently outperforms both the global and local controllers. This superior performance stems from the unique architecture of the NCR controller, which is independent of specific parameter choices. Notably, the NCR controller not only facilitates the activation of less active modules through cross-activation mechanisms but also effectively utilizes the resource consumption within the controller itself. These findings emphasize the critical role of carefully designing the topology of multimodule controllers to ensure robust performance.

How does group availability affect distributional equity of outdoor physical activity facilities? Evidence from Nanjing, China

ABSTRACT Most studies have measured the distributional equity of outdoor physical activity facilities (OPAFs) considering the unified accessible quantity and ignored the disparity of group availability. This study adopts a multidimensional approach to measure the distributional equity of OPAFs from the levels of city and residential units. Considering the old city of Nanjing as a sample, we first categorised the existing OPAFs into equipped sites, multifunctional sites, and trails and quantified the size and composition of three age groups in each residential unit. Second, we modularised OPAFs’ services through which each service type corresponds to one physical activity (PA) module and identified each module’s available groups. Third, we adopted accessibility, diversity, and supply-demand structure consistency (SDSC) to measure the distributional equity of OPAFs at two levels. The results showed that at the city level, the gap in the diversity of the modules between Group C (60 years old and above) and Groups A (15–59 years old) and B (60 years old and above) was more significant than that of accessible quantity, while the mean SDSC for Group C was much higher than those for Groups A and B. At the unit level, the differences in OPAFs’ group availability generated more significant differences in distributing diversity and SDSC than in the distribution of accessibility. Compared to traditional assessments, this tool integrates the disparity of OPAFs’ availability among different groups into the equity measurement, which can enhance the analytical precision and granularity and provide tailored OPAF optimisation strategies.

A Competition-Based Strategy for the Isolation of an Anti-Idiotypic Blocking Module and Fine-Tuning for Conditional Activation of a Therapeutic Antibody.

The masking of therapeutic antibodies by the installation of a blocking module that can be removed under certain physiological conditions, is becoming increasingly important to improve their safety and toxicity profile. To gain access to such masking units, we used chicken immunization in combination with yeast surface display and a competition-based FACS screening campaign to obtain anti-idiotypic single-chain Fv (scFv) fragments. This approach promotes the identification of functional masking units, since specificity and high affinity do not necessarily guarantee a paratope blocking effect. This strategy was used to isolate a scFv masking unit for the therapeutic antibody 6G11 (BI-1206), which is currently in clinical trials for the treatment of B-cell lymphoma to block the inhibitory Fcγ receptor IIB (CD32b). N-terminal fusion of the anti-idiotypic scFv to the 6G11 light chain successfully abolished binding to FcγRIIB in vitro. For conditional activation, a cleavable linker for the tumor-associated protease MMP-9 was implemented. To improve demasking efficiency, the affinity of the scFv mask was attenuated through rational design. The substitution of one key amino acid in the masking scFv reduced the affinity toward the 6G11 paratope by factor 10 but still mediated 9800-fold blocking of receptor binding. Proteolytic demasking allowed full recovery of therapeutic antibody function in vitro, supporting the concept of conditional antibody activation using this anti-idiotypic binding module.

Enhancing power quality in wireless DC power supplies through active power filtering: A computer simulation approach

This paper presents a computer simulation model for a high-power factor wireless DC power supply system, integrating an active power filter (APF) at the rectifier stage on the transmitter side using a rectifier boost technique. The APF, employing a MOSFET switch regulated by active pulse width modulation (APWM) within a current control loop, addresses pulsating and distorted AC supply currents caused by non-linear loads. A robust closed-loop control mechanism, including a subtractor circuit, proportional-integral (PI) controller, and comparator, ensures the generation of a continuous sinusoidal waveform synchronized with the supply voltage. The model utilizes a high-frequency inverter to convert DC to AC, which is then wirelessly transmitted via wireless power transfer (WPT) technology and converted back to DC by a high-frequency rectifier. MATLAB/Simulink simulation results show a significant reduction in total harmonic distortion (THD) of the AC supply current, complying with IEEE 519 standards. Selected results are presented to verify the proposed method's effectiveness in reducing harmonic distortions and enhancing power quality. This study highlights the advantages of WPT in scenarios where traditional wired connections are impractical and underscores the potential of this system for real-world applications, particularly in developing high-power factor wireless DC power supply systems.

Optimal drag-based collision avoidance: Balancing miss distance and orbital decay

The increasing number of objects in Low Earth Orbit makes active collision avoidance imperative for satellites operating in this region. For satellites non equipped with propulsion systems, the collision risk can be mitigated by exploiting the active modulation of aerodynamic forces through the ballistic coefficient. This article proposes a novel and high-fidelity optimal control approach for collision avoidance via aerodynamic drag modulation for an unpropelled SmallSat. Central to this approach is a cost function that jointly maximizes the miss distance while minimizing orbital decay during the maneuver. Moreover, the proposed approach has been rigorously tested through its application to the real-world scenario of the SOURCE satellite, slated for launch in 2025. For the satellite under investigation and a maneuver altitude of 350km, an in-track separation distance of around 22km can be accomplished within a warning time of 24h, which is large enough to conclude that the collision was successfully avoided. As a downside, however, this results in an additional loss in the semi-major axis of 165m and thus a reduced lifetime of the satellite. This balance between separation distance and additional loss in altitude can be flexibly adjusted by the user, which is demonstrated extensively in the article by means of a parameter study. Compared to the widespread use of chemical propulsion systems, this strategy naturally demands longer warning times due to the significantly lower available forces, and also radial offsets to the potential collision object cannot be in this case. Nevertheless, it offers a very promising alternative for active collision avoidance, especially for low-altitude applications.

Modulated ultrasound speakers – A common framework for analyzing air pump speakers

In this article we describe a new approach to sound generation based on active modulation of ultrasound. Active modulation of ultrasound provides an alternative to dynamic drivers and enables to reduce the size and volume of speakers. This feat in apparent contradiction to basic acoustics. In the article we provide for the first time an explanation of the underlying physics of modulated ultrasound speakers using a holistic lumped element model. Using the model, we explore different archiectures and highlight an archicture providing maximal sound pressure level for a given membrane area and displacement. Devices implementing the architecture were fabricated using MEMS technology. The sound pressure level response of the fabricated devices is compared to simulations highlighting the unique properties of the modulated ultrasound speakers.