Browse Articles

Study on spatial turning maneuver of underwater towed system for submersibles

Learning predictive signals within a local recurrent circuit

The predictive coding hypothesis proposes that top–down predictions are compared with incoming bottom–up sensory information, with prediction errors signaling the discrepancies between these inputs. While this hypothesis explains the presence of prediction errors, recent experimental studies suggest that prediction error signals can emerge within a local circuit, that is, from bottom–up sensory input alone. In this paper, we test whether local circuits alone can generate predictive signals by training a recurrent spiking network using local plasticity rules. Our network model replicates experimentally observed features of prediction errors, such as biphasic neural activity patterns and context dependency. Our findings shed light on how synaptic plasticity can shape prediction errors and enable the acquisition and updating of an internal model of sensory input within a recurrent neural network.

A robust single-antenna GNSS/MEMS fusion structure for reliable attitude determination in challenged environments

Cosmic ray–driven electron-induced reaction theory quantifies spatiotemporal variations in lower-stratospheric ozone and temperature

Cosmic rays (CRs) play an important role in affecting planetary and interstellar climate and environment. Here, we apply the CR–driven electron-induced reaction (CRE) theory of ozone depletion to obtain a quantitative understanding of spatiotemporal variations in Earth’s lower-stratospheric ozone (LSO) and temperature, which provide fingerprints for the mechanisms of ozone depletion and examine the impact of nonhalogen greenhouse gases on the ozone layer. We first show from observations that both LSO and temperature display pronounced 11-y cyclic variations over Antarctica and mid-latitudes, while weak (no apparent) cyclic variations over the tropics. These observations are consistent with the prediction by the CRE theory. Second, our no-parameter CRE theoretical calculations give the vertical profile of ozone loss in perfect agreement with observations at the Antarctic Syowa station and reproduce well the time-series variations of both LSO and temperature in the polar, mid-latitude, and tropical regions, including the previously reported large ozone depletion in the lower stratosphere over the tropics. The results also demonstrate that both LSO and temperature are controlled by CRs and ozone-depleting substances (ODSs) only. Moreover, CRE calculations exhibit complex phenomena in future trends of LSO and temperature, which are strongly affected by the future trend of CR fluxes. The latter might even lead to almost no recovery of the ozone hole over Antarctica and no returning to the 1980 level over the tropics by 2100. This study greatly improves quantitative understanding of ozone depletion and climate in the global lower stratosphere and offers predictions on future trends.

Centrifuge-free cell radiolabeling using acoustophoresis

Abstract Tracking ex vivo radiolabeled cells using radionuclide imaging such as positron emission tomography is an emerging method for evaluating cell-based therapies. Traditional radiolabeling requires a centrifuge in multiple steps to optimize labeling and remove unbound radiotracers. With the goal of automating the radiolabeling procedure, we explored an acoustophoresis-based approach for radiolabeling cells, eliminating the need of using a centrifuge, simplifying the design of this future device. The AcouWash 2 (AcouSort AB, Lund, Sweden), an acoustophoresis based cell washing device, was evaluated for its ability to label EL4 murine T lymphoblasts with zirconium-89 (89Zr)-oxine without centrifugation. The AcouWash 2 successfully replaced the culture medium with a protein-free buffer, as required for 89Zr-oxine cell labeling. Additionally, it was able to concentrate EL4 cells by a factor of 5.6 ± 0.4, achieving or exceeding the optimal labeling cell density. After cell incubation with 89Zr-oxine, AcouWash 2 exchanged the incubation solution with a solution for infusion, removing unbound 89Zr-oxine. These steps eliminated the need for centrifugation at each stage of the labeling procedure. The resulting radiolabeled EL4 cells exhibited labeling metrics, specific activity, percent labeling efficiency, percent free 89Zr-oxine in the suspension buffer and cell viability, comparable to those obtained from conventional centrifuge-based method. Our results demonstrate that the radiolabeling can be performed entirely using acoustophoresis, which paves the way for developing a fully automated radiolabeling device based on acoustophoresis technology.

Structural state governs the mechanism of shear-band propagation in metallic glasses

Shear bands (SBs) play a critical role in determining the mechanical behavior of metallic glasses (MGs). However, the rapid dynamics and highly localized nature of SB propagation present significant challenges for direct observation of their atomistic mechanisms using experimental techniques. In this study, we employ hybrid molecular dynamics/Monte Carlo simulations to investigate the atomic-scale mechanisms of SB propagation in Mg 65 Cu 25 Y 10 MGs, prepared using cooling rates as slow as 10 4 K s −1 —comparable to experimental casting conditions and significantly slower than the 10 10 K s −1 rates previously employed in atomistic simulations. Our results reveal a qualitative shift in SB propagation mechanisms as the structural state evolves with decreasing cooling rates. In hyperquenched MGs, SB propagation occurs intermittently, characterized by a “stop-and-go” motion driven by sequential activation and coalescence of multiple shear transformation zones (STZs) separated by vortex-like fields. In contrast, slowly cooled MGs exhibit continuous and rapid SB propagation, mediated by localized shear softening and the formation of large vortex fields, indicative of a more collective structural response. This transition arises from significant differences in the number density and spatial distribution of activated STZs across different structural states. These findings provide insights into the microscopic dynamics of SB initiation and propagation in MGs, highlighting how the structural state can be strategically tuned to control SB behavior. This opens up different opportunities for optimizing the mechanical performance of MGs for targeted engineering applications.

In vitro susceptibility testing of Trichomonas gallinae strains to proton pump inhibitors and nitroimidazoles

Abstract Trichomonas gallinae is a unicellular obligate parasite predominantly spread among Columbiformes through the sharing of feeding and drinking stations, as well as during the feeding of squabs with crop milk. It primarily causes lesions in the pharynx and esophagus, impairing the birds’ ability to eat, drink, and even breathe, thus it is potentially fatal for infected birds. Currently, five nitroimidazole derivatives are available for treatment, which, however, are prohibited for use in food-producing livestock. The aim of this study is to explore alternative treatment options against Trichomonas gallinae . Parasites were collected from urban pigeons using a sterile swab from the trachea. The number of live trophozoites (per mL) was determined using a Burker chamber. Subsequently, they were treated with solutions of pantoprazole, rabeprazole dissolved in distilled water, and omeprazole, esomeprazole, and lansoprazole dissolved in ethanol. Omeprazole was found to be the most effective, achieving complete eradication at a concentration of 250 µg/mL, whereas pantoprazole and esomeprazole required a concentration of 1000 µg/mL to achieve the same result. Rabeprazole and lansoprazole were significantly less effective, requiring a concentrations of 2000 µg/mL and 4000 µg/mL for complete eradication, respectively. Overall, our findings suggest that proton pump inhibitors may serve as viable alternative treatment options for Trichomonas gallinae infection. The development of benzimidazole-structured compounds appears promising for the future creation and testing of new, alternative, and safer agents.

Macroevolutionary changes in natural selection on codon usage reflect evolution of the tRNA pool across a budding yeast subphylum

Across taxonomical domains, synonymous codons of an amino acid are found to be used at unequal frequencies within genomes. This codon usage bias (CUB) is highly variable across species. Genome-wide CUB reflects a balance between adaptive and nonadaptive microevolutionary processes within a species. Variation in microevolutionary processes results in across-species variation in CUB. As CUB is tightly linked to important molecular and biophysical processes, it is critical to understand how changes to these processes are linked to changes in microevolutionary processes. We employed a population genetics model to quantify natural selection and mutation biases on a per-codon basis across the Saccharomycotina budding yeast subphylum. We find that the strength of natural selection and mutation biases varied significantly between closely related yeasts. Across-species variation in natural selection reflected the evolution of tRNA gene copy number (tGCN). Additionally, we find that changes to tRNA modification expression can contribute to changes in natural selection across species independent of changes to tGCN. Both lines of evidence support the link between the evolution of the tRNA pool and natural selection in codon usage through changes in the translation efficiency of a codon. Furthermore, we show that changes to tGCN often reflected changes in genome-wide GC%, suggesting changes in the tRNA pool reflect changes in mutation biases. Our work establishes how changes in microevolutionary processes impact changes in molecular mechanisms, ultimately shaping the macroevolutionary variation of a trait.

Intratumoral expression of IL-12 and CD40 ligand (CD154) from plasmids generates antitumor responses that eliminate tumoral T regs

The highly conserved C-terminal end segment of troponin T binds tropomyosin and actin to function in modulating contractile kinetics

The troponin (Tn) complex plays a central role in regulating striated muscle contraction and relaxation. Troponin T (TnT) and troponin I (TnI) are two of the three subunits of Tn, which have evolved from a TnI-like ancestor gene. Proteolytic removal of the evolutionarily added N-terminal variable region of cardiac TnT, as occurs in acute ventricular contractility-afterload mismatch, brings back a TnI-like molecular conformation and function to reduce ventricular systolic velocity, elongates ejection time, and sustains stroke volume. Investigating the underlying mechanism found in addition to the two previously known tropomyosin (Tm)-binding sites another Tm-binding site in the highly conserved C-terminal end segment of TnT, which is also an F-actin binding site. Its functionality is retained in the form of free peptide with an effect on cardiac muscle contractile kinetics. Hypertrophic cardiomyopathy mutations in this segment significantly decrease Tm-binding affinity. The finding of a third Tm-binding site and localizing the actin-binding site of TnT revise our understanding of the dynamic interactions between Tn and actin thin filament with physiological and pathophysiological implications.

A prospective study on the role of non-invasive tests in the evaluation of diabetes mellitus associated steatotic liver disease

Onset of cavitation and vapor bubble development over hydrophilic and hydrophobic surfaces

Cavitation, the formation of vapor bubbles as the liquid pressure is reduced below the saturated vapor pressure, often requires a substantial negative relative pressure in a pure liquid. Classical nucleation theory (CNT) provides an estimate for the rate of cavitation but there is often a disconnect between the predictions at the molecular scale compared to observations at the macroscale. We report on mesoscale simulations of cavitation based on many-body dissipative particle dynamics (mDPD), a coarse-grained molecular dynamics (MD), which bridges the two scales. A liquid layer is confined between smooth planar walls at a constant temperature, while the pressure is reduced slowly by expanding the wall-bounded domain. The wetting properties of the liquid are determined by the parameters of the interaction potentials. With hydrophilic walls, homogeneous nucleation is observed in the liquid bulk. As a bubble forms and grows, it creates a strong pressure pulse and oscillations that cause other bubbles that may have formed slightly later to collapse. For a nearly neutral wall with a contact angle close to 90 ° , heterogeneous nucleation occurs at the walls at a smaller negative pressure and generates weaker pressure oscillations. With hydrophobic walls or seed particles, heterogeneous nucleation readily occurs, where fluctuations and the merger of transient surface bubbles are significant.

High-resolution fecal pharmacokinetic modeling in mice with orally administered antibiotics

Comparing conventional and alternative mechanisms of discovering and accessing the scientific literature

This study compares the bibliographic and full-text coverage of 15 conventional and alternative discovery/access mechanisms: two multidisciplinary library databases (Scopus and the Web of Science Core Collection), five single-subject databases, the integrated library search (ILS) mechanism of Manhattan University, a scholarly search engine (Google Scholar), two web-based scholarly databases (Dimensions and OpenAlex), two academic social networks (Academia.edu and ResearchGate), and two pirate sites (Anna’s Archive and Sci-Hub). The analysis is based on known-item searches for 875 target documents in chemistry, materials science, cardiology, public health, economics, education, and psychology. Overall, Google Scholar, OpenAlex, and the ILS are the most comprehensive sources of bibliographic records. Google Scholar’s coverage rate is higher than that of all the Manhattan University databases combined, and Scopus—the most comprehensive multidisciplinary library database—has a lower bibliographic coverage rate than Google Scholar, both of the web-based scholarly databases, one of the two ASNs, and one of the two pirate sites. In terms of full-text coverage, the best multidisciplinary options are the ILS, Google Scholar, and the two pirate sites. Although several of the alternative discovery/access mechanisms are deficient in terms of their user interfaces, search capabilities, and metadata, they nonetheless provide excellent bibliographic and full-text coverage of the scholarly literature. In contrast, many single-subject library databases provide very incomplete coverage of their own subject areas. These findings have implications for scholars and students as well as system-wide implications for the use, development, and evaluation of information resources.

Data-driven nutritional assessment of urban food landscapes: insights from Boston, London, and Dubai

Comparison of sensitivity of rhesus and cynomolgus macaque for acute radiation effects

Abstract Radiation medical countermeasure development under the United States Food and Drug Administration Animal Rule needs validated large animal models of acute radiation syndrome. Such a well-established large animal model is the rhesus nonhuman primate. The potential use of the rhesus for other high priority areas and limited supply of such animals emphasizes the need to validate other large animal models, in particular other macaque models, in order to compensate for the lack of rhesus macaques for radiation countermeasure development. Based on existing data, cynomolgus macaques, Macaca fascicularis , are a viable alternative, but need further characterization. Reliance on such animal models requires that the models are well validated. Data gathered from rhesus and cynomolgus macaques under the same experimental conditions are not available; therefore, the authors compared and contrasted here the radiosensitivity of both macaques receiving same levels of clinical support and exposed to same doses of total-body gamma-radiation, and at same dose rates using same radiation source. Under matched experimental conditions, significant differences between acutely irradiated rhesus and cynomolgus macaques relative to the rates of survival and blood cell changes were observed. The presented data demonstrate that the cynomolgus macaque is more sensitive to ionizing radiation exposure. Overall, data supports the concept that the cynomolgus macaque is a viable, potentially useful alternative large animal model for the evaluation of radiation medical countermeasures. For comparative purposes however, additional studies with both macaques under identical experimental conditions, such as levels of clinical support and different radiation qualities with males and females ran concurrently in future will be critically important.

Signal peptide–independent secretion of keratin-19 by pancreatic cancer cells

The exclusion of T cells causes immune escape of pancreatic ductal adenocarcinoma (PDA). T cell exclusion is mediated by the interaction between CXCR4 on T cells and its ligand, CXCL12, which is complexed to keratin-19 (KRT19) on the surface of PDA cells. KRT19 secretion by PDA cells is essential to this process but is unusual because KRT19 lacks an endoplasmic reticulum (ER)-directing signal peptide (SP). By using biotinylation by an ER-restricted TurboID system and a split-GFP assay in PDA cells, we demonstrate that KRT19 enters the ER via its “head” domain. Additionally, KRT19 is shown to interact with the signal recognition particle and its secretion is sensitive to canonical protein secretion inhibitors. In vivo, mouse tumors formed with ER-TurboID-expressing PDA cells contain biotinylated KRT19. In contrast, keratin-8 (KRT8), which colocalizes with KRT19 on the surface of PDA cells, does not enter the ER. Rather, KRT8 is externalized via secretory autophagy possibly in a complex with KRT19. Thus, despite lacking a classical SP, PDA cells secrete KRT19 to capture CXCL12 and protect against immune attack.

Dietary ecology of the endangered seahorse Hippocampus haema unveiled through stable isotope analysis

The sediment transport mechanics driving lateral accretion in muddy meanders

The discovery of paleo-meanders on Mars and debates about the occurrence of meandering on prevegetation early Earth have stimulated field studies of channel morphology and deposit stratigraphy in arid environments. They show that mud can provide the cohesive strength to retard outer bank erosion, enabling inner bank lateral accretion (including mud deposition) to keep pace and thus sustain meandering. The process by which mud is deposited in the lateral accretion deposits, however, is poorly known. Building on previous fieldwork in the muddy meandering Quinn River, we use Delft3D and the Partheniades–Krone model for cohesive sediment transport to predict erosion and deposition patterns in a 2,300 m long reach. While flocculation of mud increases the settling velocity and hence the likelihood of deposition, the standard metric for distinguishing washload from suspended load, (i.e. settling velocity to shear velocity ratio), does not indicate relative deposition rate. Mud deposition is driven by the product of settling velocity times basal concentration: w s c b . Relatively low w s but high c b can induce deposition. We show that with sufficiently high basal concentrations, significant net lateral accretion deposition occurs in areas where elevated flocculation settling velocities are > 100 times lower than the local shear velocity. Observed grain size distributions of lateral accretion deposits are predicted. Just by introducing a period of elevated mud load with no change in discharge creates a distinct muddy interbed. Our model points to multiple ways lateral accretion deposits can vary sedimentologically, including creating mud-sand couplets, and lead to single thread, active meandering channels in muddy rivers.

A novel vascular stent and insert concept to improve hemodynamics and support vascular health

Abstract Obstruction of vessels is one of the most common health issues in the world and various methods of treatments have been offered, including medication therapy, stenting, and bypass surgery. However, recurrence of blockage is a major issue facing patients. The present work assesses the performance of a new innovative design of stents featuring two spirals, called ‘inserts’, which will create a rotating flow inside the vessel. Three different cases of artery and bypass configurations were studied and the results showed that the stent and inserts increased the axial and secondary velocity significantly. At a plane located 1 mm after anastomosis and at t = 0.25 s, the axial velocity was 23% higher for a case with stent and insert compared to the baseline configuration i.e., without stent/insert. In addition, it was found that the presence of the insert increases the wall shear stress (WSS). The maximum WSS among the three cases reached 113 Pa, which was 94% higher than the baseline case. The findings highlight the potential of the proposed stent/insert design in improving the hemodynamic parameters in the graft, anastomosis region, and the host artery, which in turn, could enhance the patency and longevity of the bypass graft.