Physical Processes Research Articles

Calculation Method for Particle Self-Regulation Servo Based on Discrete Element Method

Particle Flow Code, as noncontinuous media calculation software, has found extensive applications in geotechnical engineering research. To simulate real physical processes, the commonly utilized servo-computing methods involve adjusting the boundaries to modify the model’s stress state. However, this approach alters the model’s initial boundaries, thereby compromising computational accuracy. Addressing this issue, this paper introduces a particle self-regulation servo-computing method. This method controls the internal particle self-adjustment and completes the servo through error analysis. On the basis of the error analysis of the average stress within the particle system and the servo stress during the iterative process, the method automatically calculates the change in particle size within the system, achieving rapid convergence to servo stress tolerance after finite number of iterations. Validation through uniaxial compression tests and complex slope cases indicates that this particle self-regulation servo method yields an error of less than 5% compared with conventional rigid servo methods. That is, it accurately achieves numerical simulation state control without altering the outer contours of the boundary model. The proposed computational method is applicable to servo calculations for irregular models in two or three dimensions, providing a viable approach for stress control in models under complex conditions.

Spectroscopic Phenological Characterization of Mangrove Communities

Spaceborne spectroscopic imaging offers the potential to improve our understanding of biodiversity and ecosystem services, particularly for challenging and rich environments like mangroves. Understanding the signals present in large volumes of high-dimensional spectroscopic observations of vegetation communities requires the characterization of seasonal phenology and response to environmental conditions. This analysis leverages both spectroscopic and phenological information to characterize vegetation communities in the Sundarban riverine mangrove forest of the Ganges–Brahmaputra delta. Parallel analyses of surface reflectance spectra from NASA’s EMIT imaging spectrometer and MODIS vegetation abundance time series (2000–2022) reveal the spectroscopic and phenological diversity of the Sundarban mangrove communities. A comparison of spectral and temporal feature spaces rendered with low-order principal components and 3D embeddings from Uniform Manifold Approximation and Projection (UMAP) reveals similar structures with multiple spectral and temporal endmembers and multiple internal amplitude continua for both EMIT reflectance and MODIS Enhanced Vegetation Index (EVI) phenology. The spectral and temporal feature spaces of the Sundarban represent independent observations sharing a common structure that is driven by the physical processes controlling tree canopy spectral properties and their temporal evolution. Spectral and phenological endmembers reside at the peripheries of the mangrove forest with multiple outward gradients in amplitude of reflectance and phenology within the forest. Longitudinal gradients of both phenology and reflectance amplitude coincide with LiDAR-derived gradients in tree canopy height and sub-canopy ground elevation, suggesting the influence of surface hydrology and sediment deposition. RGB composite maps of both linear (PC) and nonlinear (UMAP) 3D feature spaces reveal a strong contrast between the phenological and spectroscopic diversity of the eastern Sundarban and the less diverse western Sundarban.

Kilometer-scale ocean processes behind the variability of the Island Mass Effect in the Maldives

The Island Mass Effect (IME) around the Maldives is responsible for intense blooms with distinct seasonal patterns. These blooms sustain the fishing industry of the archipelagic nation, a vital source of income that occupies about 30% of the population. Through high resolution ocean simulations, we explore the physical processes responsible for the increased productivity and its observed variability, and their sensitivity to changes in land distribution. Year-round the frictional break of the currents in the presence of shallow bathymetry produces a strong vertical shear in the flow that favors vertical mixing, independently of the currents direction. The impact of this mixing is visible at the ocean surface during March and April, when the mixed-layer is shallow and the ocean currents are generally weak. A different mechanism than observed in spring modulates the IME during the monsoon seasons, in both winter and summer, when the zonal currents forced by the strong winds cross the archipelago: the flow accelerates while squeezing between the atolls, giving rise to intense wakes, and strong upwelling originates in the lees in response to the kilometer-scale flow divergence. This upwelling creates an asymmetric cooling signal in the lee of the islands and obfuscates the effects of the enhanced vertical mixing. The land reclamation efforts being planned on some of the islands may undercut the upwelling that drives the blooms during the monsoon seasons.

Histo-pillar strip for optimal histogel block construction and biomarker analysis in 3D-lung cancer patient-derived organoids.

This study proposed an optimized histogel construction method for histological analysis by applying lung cancer patient-derived organoids (PDOs) to the developed histo-pillar strip. Previously, there is the cultured PDOs damage problem during the histogel construction due to forced detachment of the matrigel spots from the 96-well plate bottom. To address this issue, we cultured PDO on the proposed Histo-pillar strips and then immersed them in 4% paraformaldehyde fixation solution to self-isolate PDO without damage. The 4 μL patient-derived cell (PDC)/Matrigel mixtures were dispensed on the surface of a U-shaped histo-pillar strip, and the PDCs were aggregated by gravity and cultured into PDOs. Cultured PDOs were self-detached by simply immersing them in a paraformaldehyde fixing solution without physical processing, showing about two times higher cell recovery rate than conventional method. In addition, we proposed a method for embedding PDOs under conditions where the histogel temperature was maintained such that the histogel did not harden, thereby improving the problem of damaging the histogel block in the conventional sandwich histogel construction method. We performed histological and genotyping analyses using tumor tissues and PDOs from two patients with lung adenocarcinoma. Therefore, the PDO culture and improved histogel block construction method using the histo-pillar strip proposed in this study can be employed as useful tools for the histological analysis of a limited number of PDCs.

Abdominal imaging in precocious puberty in girls: can imaging determine onset of puberty?

Precocious puberty in girls is defined by the appearance of secondary sex characteristics before the age of 8 years. Precocious puberty is either peripheral or central. In most cases, the cause of central precocious puberty is unknown. Rapidly progressive forms of central precocious puberty may benefit from puberty suppression to prevent compromised final height and psychosocial problems related to the physical changes. Idiopathic central precocious puberty in girls can be a challenging diagnosis. Clinical examination, evaluation of growth charts, bone age, and hormonal tests are part of the workup. The role of pelvic ultrasound to evaluate pubertal features of the internal genitalia in this context is controversial. In this paper, we havereviewed the literature to find the scientific bases for several proposed ultrasound parameters and cutoff values for the determination of onset of puberty in girls with suspected central precocious puberty. There are no reliable cutoffs for the measurements of uterus and ovaries for the diagnosis of central precocious puberty and there is overlap in the appearance of the organs in both prepubertal and pubertal girls. The interpretation of the findings on pelvic ultrasound must be done with caution and always in close communication with the referring clinicians.

Covalent surface modification of single-layer graphene-like BC6N nanosheets with reactive nitrenes for selective ammonia sensing via DFT modeling

Novel graphene-like nanomaterials with a non-zero bandgap are important for the design of gas sensors. The selectivity toward specific targets can be tuned by introducing appropriate functional groups on their surfaces. In this study, we use first-principles simulations, in the form of density functional theory (DFT), to investigate the covalent functionalization of a single-layer graphitized BC6N with azides to yield aziridine-functionalized adducts and explore their possible use to realize ammonia sensors. First, we determine the most favorable sites for physical adsorption and chemical reaction of methylnitrene, arising from the decomposition of methylazide, onto a BC6N monolayer. Then, we examine the thermodynamics of the [1 + 2]–cycloaddition reaction of various phenylnitrenes and perfluorinated phenylnitrenes para-substituted with (R = CO2H, SO3H) groups, demonstrating favorable energetics. We also monitor the effect of the functionalization on the electronic properties of the nanosheets via density of states and band structure analyses. Finally, we test four dBC6N to gBC6N substrates in the sensing of ammonia. We show that, thanks to their hydrogen bonding capabilities, the functionalized BC6N can selectively detect ammonia, with interaction energies varying from −0.54 eV to −1.37 eV, even in presence of competing gas such as CO2 and H2O, as also confirmed by analyzing the change in the electronic properties and the values of recovery times near ambient temperature. Importantly, we model the conductance of a selected substrate alone and in presence of NH3 to determine its effect on the integrated current, showing that humidity and coverage conditions should be properly tuned to use HO2C-functionalized BC6N-based nanomaterials to develop selective gas sensors for ammonia.

Применение машинного обучения и интеллектуального анализа данных в автоматизированной системе неразрушающего вихретокового контроля поверхностного слоя деталей подшипников

Changing the properties of the material during physical and mechanical processing can significantly reduce the working life of the manufactured product, therefore it is important to control the quality of the surface layer of the parts. To solve this problem, non-destructive testing techniques such as etching, visual, capillary, magnetic powder, ultrasonic, vibration, eddy current methods are used at bearing enterprises. The article discusses the physical foundations of the presented techniques and provides their comparative analysis. Machine vision and digital signal processing approaches can be used to automate the processing of the results of non-destructive testing of the surface layer of bearing parts within the framework of the Industry 4.0 concept. From the point of view of productivity and the possibility of integration into the production system, the eddy current method is the most promising, the result of surface control in this way is an array of digital values. The development of modern methods of information analysis makes it possible to efficiently process a large amount of data, and machine learning makes it possible to solve problems of classification, regression, etc. This article provides methodological support for the development and application of an automated eddy current control system using machine learning and data mining methods. The works of scientists devoted to the processing of the results of the shock control of various objects, including bearing parts, are considered, it is noted that previously attention had not been paid to the issue of a reasonable choice of a machine learning model for recognizing defects on the surface of parts. The possibility of using the median polishing method to transform the eddy current signal is shown. The development and implementation of a bearing defect recognition system based on the methodological support presented in this paper can significantly improve the efficiency of product quality control and optimize the technological process.

General practitioner and practice nurses perspectives on implementation of the 75+ health assessment: Implications for dementia care and well-being.

The uptake of the health assessment for persons aged 75 years and older (75 + HA) remains low. Repeat assessments provide an opportunity to identify areas of change in cognitive function which may mark the onset of dementia. We aimed to explore general practitioner (GP) and practice nurse experiences of implementing the 75 + HA with a focus on clinical considerations for dementia care. An interpretative qualitative study involving interviews with 15 GPs (female = 11, male = 4) and 5 practice nurses (all female). Data were analysed using an inductive thematic approach. The majority of GPs (n = 11) worked in metropolitan settings and four GPs worked in regional settings across NSW. All participants worked in separate clinics, except for two GPs and one practice nurse who worked within the same metropolitan clinic. Distinct themes emerged regarding participants experiences of implementing the 75 + HA for patients with dementia: (1) negotiating aged care is complex and facilitated by a comprehensive assessment; (2) implementing work practices that support the 75 + HA in patients with cognitive decline; and (3) variations in follow up of findings and implications for care. The 75 + HA provides an opportunity for monitoring and acting on emergent physical and cognitive health changes. Increased engagement and support towards implementing the 75 + HA, particularly in the context of dementia, may facilitate the instigation of interventions. While some participants in this study were confident with identifying and managing cognitive decline, the majority relied on geriatricians to confirm dementia diagnosis and refer to community support services. We suggest the need for greater initiatives and clinical guidelines to assist GPs in the identification and management of cognitive decline. From a nursing perspective, this study highlights the valuable role of nurses towards assessment and management of issues raised in the health assessment for persons aged 75 years and older. However, more resources are needed to enable nurse time for adequate follow-up care.

Finding Passive Galaxies in H i-MaNGA: The Impact of Star Formation Rate Indicator

H i-rich galaxies typically have high star formation rates (SFRs), but there exist interesting H i-rich and low star-forming galaxies. Previous work on a sample of these galaxies identified from H i-Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) (H i follow-up to the MaNGA survey) using an infrared indicator of specific-SFR (sSFR; namely W2 − W3 < 2) could find no single physical process to explain their unusual behavior. The method by which galaxies are identified as low sSFR may be important in this conclusion. In this Research Note, we explore how an H i-rich, low sSFR sample of H i-MaNGA galaxies differs using Hα, single stellar population, and ultraviolet estimators of SFR. We find that samples are statistically similar to each other so long as W2 − W3 < 2 is interpreted as corresponding to sSFR < 10−11.15 yr−1.

LGBTQI Sexual Well-Being and Embodiment After Cancer: A Mixed-Methods Study

ABSTRACT This study examined lesbian, gay, bisexual, transgender, queer and intersex (LGBTQI) cancer patients’ sexual well-being post-cancer, and the associations between sexual well-being and social support, physical concerns, distress, quality of life (QOL), and coping. We used a mixed-methods approach, including 430 surveys and 103 interviews, representing a range of tumor types, sexual and gender identities, age groups, and intersex status. The findings indicated that LGBTQI people with cancer experience declines in sexual well-being following cancer, which are associated with reduced QOL, greater physical concerns, and lower social support. The perceived helpfulness of coping mechanisms was associated with greater sexual well-being across genders, with cisgender men reporting the sharpest declines in sexual well-being and highest use of coping mechanisms. Across all groups, searching for information online was the most frequently used coping mechanism, with support groups and counseling the most under-utilized. Qualitative findings facilitated interpretation of these results, providing examples of ways in which cancer impacted sexual well-being and how physical changes influence sexual embodiment or desire to engage in sex. Concerns about reduced sexual desire and activity, associated with changes to breasts, vulva, vagina, penis, erectile dysfunction, incontinence, scarring, and stoma, reflect previous findings in the non-LGBTQI cancer population. Unique to this population are the impact of physical changes on LGBTQI embodiment, including disruption to sexual and gender identities, and feelings of disconnection from queer communities. Addressing LGBTQI sexual well-being within oncology healthcare is a matter of sexual and reproductive justice, for a population whose needs are often overlooked within cancer care.

Comparative Study of the Foaming Behavior of Ethylene–Vinyl Acetate Copolymer Foams Fabricated Using Chemical and Physical Foaming Processes

Comparative Study of the Foaming Behavior of Ethylene–Vinyl Acetate Copolymer Foams Fabricated Using Chemical and Physical Foaming Processes

Revealing the mechanism of subsynchronous torsional interaction caused by LCC-HVDC from the perspective of vector synchronization

Line-commutated converter-based high voltage direct current transmission (LCC-HVDC) has been widely applied worldwide due to its great advantages in realizing long-distance and large-capacity power transmission. However, it may also lead to instability problems, including subsynchronous torsional interaction (SSTI). This destructive phenomenon greatly threatens the safe and stable operation of power systems and has been widely concerned since the 1970 s. Existing literature has found that SSTI is caused by DC current control of rectifier station. However, the physical mechanism of this phenomenon has not been clarified clearly, which hampers further understanding of how negative damping is generated and whether it is evitable. To fill this gap, the physical process of SSTI caused by LCC-HVDC is clarified through the perspective of vector synchronization. Based on this, the negative damping mechanism is revealed. The influence of control on damping is also studied with the contribution of different control loops quantified. All results are verified through time-domain simulations and damping torque analysis.

Investigation on methane hydrate formation behaviors in deep-sea methane seepage environments

Deep-sea cold seep is a natural phenomenon where methane leaks from the sea floor. Methane can be partially conversed through physical, chemical, and biological processes, but the excess methane that remains uncaptured escapes into the atmosphere and contributes to the greenhouse effect. Physical carbon sequestration via hydrate formation is a fast and high-energy density type of carbon sequestration; however, it has been largely overlooked. This study investigated hydrate formation in authigenic carbonate rocks through deep-sea geological surveys in cold seeps in the South China Sea. Investigations have shown that authigenic carbonate rocks can sequester carbon by blocking the methane plume from the seepage vents. This perspective provides a new physical carbon sequestration mode of carbonate rocks by observing the artificial collection of methane plumes in deep-sea seepage areas. The mode was simplified into two steps including the formation of a thin layer of planar hydrate film on carbonate rocks and a thick layer of hydrate through the stacking of bubbles under the thin film. Salinity, a key distinction between seawater and freshwater, was further investigated for its impact on the carbon sequestration mechanism. Results showed that saline ions in seawater had little impact on the thickening rate of the planar hydrate film but reduced the lateral growth rate of hydrates on the bubble by 60%. This reduction in the lateral growth rate greatly facilitated the three-dimensional growth, increased the hydrate thickness on the bubble, and improved the carbon sequestration efficiency. Hydrate formation on the exposed carbonate rock can effectively impede methane plume migration into upper water and atmosphere, mitigate the greenhouse effect, and present a promising strategy for carbon sequestration in deep-sea methane seepage areas.

An injectable fibronectin3-alginate hydrogel driven by dynamic dissolving equilibrium for irregular wound repair

Managing irregular wounds with varying depths presents a challenge due to the limited effectiveness of traditional dressings in promoting wound healing. Injectable hydrogels represent a promising approach for managing irregular wounds with varying depths. However, many existing hydrogels are limited by poor biocompatibility and a lack of active ingredients, which significantly undermines their effectiveness in promoting wound healing. In this study, an injectable alginate hydrogel incorporating Fibronectin3 (FN3) as the active component was developed through the modulation of Ca2+ balance and a gradual physical crosslinking process, enabling administration with a 30 G needle. This gel demonstrates remarkable self-healing properties, capable of withstanding 1500 % strain, and exhibits high biocompatibility. Moreover, blood clotting tests demonstrate a lower clotting index than gauze. Additionally, the cell scratch test shows the positive biological activity of the gel and its potential to enhance the migration of L-929 calls. Experiments on full-thickness wounds in mice significantly confirm that gels containing FN3 can effectively accelerate wound healing. In conclusion, this study presents a simple method utilizing the solvation equilibrium of Ca2+ for creating injectable hydrogels with exceptional wound repair properties, thereby indicating their promise as wound dressings in clinical applications.

The Role of Sports in Preventing and Overcoming Problems During the Transition Period Case Study of Adolescents in Indonesia: Descriptive Study

This qualitative descriptive study explores the potential of sports activities in overcoming the challenges faced in the transition phase of adolescence. The literature highlights the values ​​and role of sport in this critical time. Adolescence is a time of significant physical, emotional, and social change as individuals navigate the transition from childhood to adulthood. It is a period marked by the search for self-identity, the development of independence, and the exploration of various roles. Globalization is increasingly impacting teenagers, giving them access to a wealth of information and cultural influences from around the world. This exposure can shape their thinking, interactions, and consumption habits. Exercise has been shown to be beneficial during this time of transition, helping teens manage stress, improving their overall health, increasing self-esteem, and improving social skills. Additionally, participation in sports can foster discipline, teamwork, and leadership qualities. Therefore, sport is considered an important component of interventions aimed at overcoming challenges during adolescence.

Pengaruh Pendidikan Kesehatan Tentang Tanda Bahaya Kehamilan Pada Ibu Hamil Dengan Resiko Tinggi

Pregnancy is a normal and natural process in a woman where physical, psychological and social changes occur during pregnancy. Knowledge of pregnancy danger signs is important for the community, especially pregnant women with high risk, because if the danger signs are known early, the handling will be faster. The purpose of this study was to determine the difference in the level of knowledge of pregnant women with high risk about pregnancy danger signs before and after being given counseling at the Mejayan Health Center, Madiun Regency. This type of research is Quasy Experimental with the One Group Pre-Test-Post-Test approach. The respondents used were 17 with total sampling. The instrument used was a questionnaire that had been tested for validity. Data analysis used a paired t-test. The conclusion from the results of the data analysis obtained a p value = 0.000 which stated that there was a significant difference in the knowledge of pregnant women before and after being given health counseling about the dangers of pregnancy using leaflets and videos. It is hoped that these suggestions can be input for pregnant women to be more active in seeking information and for health workers to be more active in providing health counseling and facilitating pregnant women regarding pregnancy danger signs.

Understanding Electrophoresis and Electroosmosis in Nanopore Sensing with the Help of the Nanopore Electro-Osmotic Trap.

Nanopore technology is widely used for sequencing DNA, RNA, and peptides with single-molecule resolution, for fingerprinting single proteins, and for detecting metabolites. However, the molecular driving forces controlling the analyte capture, its residence time, and its escape have remained incompletely understood. The recently developed Nanopore Electro-Osmotic trap (NEOtrap) is well fit to study these basic physical processes in nanopore sensing, as it reveals previously missed events. Here, we use the NEOtrap to quantitate the electro-osmotic and electrophoretic forces that act on proteins inside the nanopore. We establish a physical model to describe the capture and escape processes, including the trapping energy potential. We verified the model with experimental data on CRISPR dCas9-RNA-DNA complexes, where we systematically screened crucial modeling parameters such as the size and net charge of the complex. Tuning the balance between electrophoretic and electro-osmotic forces in this way, we compare the trends in the kinetic parameters with our theoretical models. The result is a comprehensive picture of the major physical processes in nanopore trapping, which helps to guide the experiment design and signal interpretation in nanopore experiments.

Sufficiency of near-surface water ice as a driver of dust activity on comets. Rethinking the old enigma

Nearly all contemporary theoretical research on cometary dust activity relies on models depicting heat transfer and sublimation products within the near-surface porous layer. Gas flow exerts a pressure drag to the crust agglomerates, counteracting weak gravity and the tensile strength of that layer. Our interpretation of data from the Rosetta mission, and our broader comprehension of cometary activity, hinges significantly on the study of this process. We investigate the role played by the structure of the near-surface porous layer and its associated resistance to gas flow, tensile strength, pressure distribution, and other characteristics in the scenario of the potential release of dust agglomerates and the resulting dust activity. We employ a thermophysical model that factors in the microstructure of this layer and radiative heat conductivity. We consider gas flow in both the Knudsen and transition regimes. To accomplish this, we use methods such as test-particles Monte Carlo, direct-simulation Monte Carlo, and transmission probability. Our study encompasses a broad spectrum of dust-particle sizes. We evaluated the permeability of a dust layer composed of porous aggregates in the submillimetre and millimetre ranges. We carried out comparisons among various models that describe gas diffusion in a porous dust layer. For both the transition and Knudsen regimes, we obtained pressure profiles within a non-isothermal layer. We discuss how the gaps in our understanding of the structure and composition could impact tensile strength estimates. We demonstrate that for particles in the millimetre range, the lifting force of the sublimation products of water ice is adequate to remove the layer. This scenario remains feasible even for particles on the scale of hundreds of microns. This finding is crucial as the sublimation of water ice continues to be the most probable mechanism for dust removal. This study partially overturns the previously held, pessimistic view regarding the possibility of dust removal via water sublimation. We demonstrate that a more precise consideration of various physical processes allows elevation of the matter of dust activity to a practical plane, necessitating a fresh quantitative analysis.

Refinement of Global Coronal and Interplanetary Magnetic Field Extrapolations Constrained by Remote-sensing and In Situ Observations at the Solar Minimum

Solar magnetic fields are closely related to various physical phenomena on the Sun, which can be extrapolated with different models from photospheric magnetograms. However, the open flux problem (OFP), the underestimation of the magnetic field derived from the extrapolated model, is still unsolved. To minimize the impact of the OFP, we propose three evaluation parameters to quantitatively evaluate magnetic field models and determine the optimal free parameters in the models by constraining the coronal magnetic fields and the interplanetary magnetic fields (IMFs) with real observations. Although the OFP still exists, we find that magnetic field lines traced from the coronal models effectively capture the intricate topological configurations observed in the corona, including streamers and plumes. The OFP is lessened by using the Helioseismic and Magnetic Imager synoptic map instead of the Global Oscillation Network Group daily synoptic maps, and the potential field source surface + potential field current sheet (PFSS+PFCS) model instead of the current sheet source surface (CSSS) model. For Carrington Rotation 2231 at the solar minimum, we suggest that the optimal parameters for the PFSS+PFCS model are R ss = 2.2–2.5 R ☉ and R scs = 10.5–14.0 R ☉, as well as for the CSSS model, are R cs = 2.0–2.4 R ☉, R ss = 11.0–14.7 R ☉, and a = 1.0 R ☉. Despite the IMFs at 1 au being consistent with the measurements by artificially increasing the polar magnetic fields, the IMFs near the Sun are still underestimated. The OFP might be advanced by improving the accuracy of both the weak magnetic fields and polar magnetic fields, especially considering magnetic activities arising from interplanetary physical processes.

On the Intermittency of Hot Plasma Loops in the Solar Corona

A recent analysis has suggested that the heating of plasma loops in the solar corona depends not just on the Poynting flux but also on processes yet to be identified. This discovery reflects and refines earlier questions such as, Why and how are entire hydromagnetic structures only intermittently loaded with bright coronal plasma? The present work scrutinizes more chromospheric and coronal data, with the aim of finding reproducible observational constraints on coronal heating mechanisms. Six independent scans of chromospheric active-region magnetic fields are investigated and correlated to overlying hot plasma loops. For the first time, the footpoints of over 30 bright plasma loops are thus related to scalar proxies for the Poynting fluxes measured from the upper chromosphere. Although imperfect, the proxies all indicate a general lack of correlation between footpoint Poynting flux and loop brightness. Our findings consolidate the claim that unobserved physical processes are at work, which govern the heating of long-lived coronal loops.