Lower Branch Research Articles

Bifurcation boundaries analysis of the thin-walled internal resonance energy harvester

The dynamic instability of the thin-walled 1: 2 internal resonant piezoelectric vibration energy harvester is investigated. Previously work (Nie et al., 2019) derived the nonlinear electromechanical-coupled governing equations and validated them experimentally. The modulation equations are performed by the method of multiple scales. The system stability is obtained from the eigenvalues of the Jacobi matrix. Then, three types of bifurcation boundaries of the system are determined analytically and simulated numerically via Routh–Hurwitz criterion. Results show that internal resonance complicates the dynamic properties of the bifurcation region. For a large external excitation, new saddle node bifurcation regions appear in the stability diagram. Moreover, the new saddle node and Hopf bifurcation regions may intertwine. Furthermore, as the acceleration excitation increases, the system can be observed to transition to stable–unstable–stable states. The system’s high and low branch responses are fed back by the system’s large and small initial conditions. The system’s periodic and quasi-periodic motions are characterized by time response, FFT, phase trajectory, and Poincaré map. The study of the stability boundary of the piezoelectric energy harvester contributes to the harvesting of energy from ambient vibrations over a broader frequency range.

Bistability-assisted mechanical squeezing and entanglement

Based on a scheme proposed to experience the dynamical Casimir effect in optomechanical systems, we show how to squeeze mechanical motion and entangle the optical field with mechanical motion in an optomechanical system containing a parametric amplification. The scheme is based on optical bistability which emerges in the system for a strong enough driving field. By considering the steady state’s lower branch of the bistability, the system shows weak entanglement and almost no mechanical squeezing. When the steady state is on the upper branch of the bistable shape, both squeezing and entanglement are greatly enhanced. Specifically, the entanglement shows three degrees of magnitude enhancement. However, this giant entanglement is fragile against decoherence and thermal fluctuation. Regarding the mechanical squeezing, it reaches the standard quantum limit (SQL) in the upper branch of the bistability. Our proposal provides a way to improve quantum effects in optomechanical systems by taking advantage of nonlinearities. This scheme can be realized in similar systems such as superconducting microwave, and hybrid optomechanical systems.

Corneal Sensitivity and Neuropathy in Patients With Ocular Graft-Versus-Host Disease.

To assess corneal sensitivity changes in patients with ocular graft-versus-host disease using a non-contact and Cochet-Bonnet esthesiometer. In addition, we evaluate the association between corneal sensitivity and subbasal nerve changes and epitheliopathy in these patients. In this retrospective study, the clinical data and images were evaluated for 36 patients (19 female, 17 male) who fulfilled the inclusion criteria. The analyzed data included demographic and ocular surface parameters, including best-corrected visual acuity, corneal sensitivity with non-contact (mbar) and Cochet-Bonnet (cm) esthesiometer, corneal fluorescein staining (CFS) and symptoms scores, tear volume (Schirmer-I test, mm/5'), and subbasal nerve density (μm/mm2; assessed with in vivo confocal microscopy). The mean age of the study cohort was 59.9 ± 10.5 years. The mean corneal sensitivity assessed by Cochet-Bonnet and non-contact esthesiometer was 5.9 ± 0.3 cm and 7.3 ± 2.0 mbar, respectively. The ocular surface parameters included a corneal fluorescein staining (CFS) score, as per the National Eye Institute grading scheme, of 6.9 ± 3.5, and a Schirmer-I test result of 7.5 ± 6.2 mm/5 minutes.. Total corneal subbasal nerve density was inversely associated with CFS scores (r = -0.74; P < 0.001). Moreover, similar correlations between CFS scores and main trunk (r = -0.62; P < 0.001) and branch (r = -0.59; P < 0.001) nerve densities were observed. A significant correlation was found between reduced corneal sensitivity and higher CFS scores (r = 0.66; P < 0.001). Higher pressures were correlated with lower total (r = -0.83; P < 0.001), main trunk (r = -0.62; P < 0.001), and branch (r = -0.72; P < 0.001) nerve densities. The univariate analysis showed that corneal sensitivity loss (assessed with non-contact esthesiometer) was correlated with advanced age of the patients (P = 0.049) and inversely associated with total (P < 0.001), main trunk (P < 0.001), and branch (P < 0.001) nerve densities. In addition, sensitivity loss was inversely associated with punctal occlusion (cauterization (P = 0.001) or plug placement (P < 0.001). The multivariate analysis adjusted for age and punctal occlusion confirmed the associations in the univariate analysis. In this study, we observed that corneal sensitivity loss was associated with reduced main trunk, branch, and total nerve density in patients with ocular graft-versus-host disease. In addition, a significant correlation was observed between reduced corneal nerve density, corneal sensitivity, and severity of epitheliopathy.

Fast quantitative analysis of high density polyethylene using adiabatic-refocused INEPT spectroscopy

Quantitative 13C NMR serves as a potent tool for determining the microstructure of polyolefin, but it generally requires long experiment times to achieve reliable quantification, for its low natural abundance and sensitivity. We utilized refocused insensitive nuclei enhanced by polarization transfer (RINEPT) here to characterize high-density polyethylene (HDPE) with very low branch contents. Compared with the standard quantitative experiment, this approach drastically reduces the experiment time from more than 20 h to several minutes, and boosts the signal to noise ratio by fivefold per unit of time. We have effectively applied this optimized method to determine short chain branching (SCB) in HDPE with various comonomer incorporations. Using 5 mm prodigy cryoprobe can further reduce the experiment time to approximately one-tenth that obtained by conventional probes. It means the total experiment time saved could be up to 225 times. We have quantified an SCB concentration of 7 branches per 10000 CH2 in just 2 h. Furthermore, our results demonstrated excellent concordance between RINEPT and traditional 13C NMR techniques in quantifying the branch content of HDPE, thereby validating the reliability of this method.

Large-eddy simulation of vortex-induced vibration of a circular cylinder at Reynolds number 10 000

The canonical scenario of cross-flow vortex-induced vibration (VIV) of a circular cylinder in the turbulent regime, which has been studied by several physical experiments in the literature, is reexamined in this study through high-fidelity large-eddy simulations (LES) at a Reynolds number 104. The VIV response (including vibration amplitude and frequency) and hydrodynamic coefficients predicted by the present LES agree with the experimental results better than previous numerical attempts. In addition, several phenomena reported by previous experimental studies are confirmed numerically for the first time. After validating against the experiments, new VIV characteristics and physical mechanisms are explored with confidence. First, a collective analysis on the frequency spectra of the displacement, lift, and velocity signals provides a complete picture of the frequency response of the system. In contrast, the use of a single signal may miss certain aspects of the frequency response, so that caution should be exercised. Second, spanwise correlation of primary vortex shedding is examined, where relatively low correlations in the upper and lower branches are likely because the vortex shedding patterns involve complex vortex generation and interaction. Third, the effect of mass ratio (m*) of the cylinder on the VIV response is analyzed with a range of m* (=1.4–3.4) relevant to cylindrical structures used in offshore engineering (such as subsea pipelines). The variations in the amplitude response, frequency response, and hydrodynamic coefficients with m* and reduced velocity are examined in detail. The present results suggest that a lighter pipeline is more susceptible to the onset of VIV.

Outcomes using inverted iliac limb bifurcate components in fenestrated/branched endografting

BackgroundThe use of standard bifurcate pieces in fenestrated/branched endovascular aortic repair (F/BEVAR) requires adequate length from the lowest branch or fenestration to the aortic bifurcation. In patients with prior aortic surgery, the aortic bifurcation is often artificially established in a more proximal position, compromising the infrarenal length, which hinders the placement of a standard bifurcate component below the fenestrated/branched component. Short bifurcate bodies using an inverted contralateral limb have been purpose-built to address this challenge. However, reported outcomes for this device remain limited, with specific concerns about the durability of the inverted iliac limb sealing region. We sought to evaluate outcomes of F/BEVAR using an investigational inverted iliac limb bifurcate, manufactured by Cook Medical. MethodsThis study was a retrospective review of prospectively maintained data from the US-Aortic Research Consortium from 2005 to 2022. Patients were included if they underwent F/BEVAR for thoracoabdominal or complex abdominal aortic aneurysms. Patients were excluded if they did not have a bifurcate device placed. Patients were then compared based on the use of an inverted iliac limb or standard bifurcate component. The primary outcome for this study was technical success. Secondary outcomes included 30-day mortality, freedom from ischemic leg complications, freedom from type I endoleaks (TIELs), freedom from type II endoleaks (TIIELs), freedom from type III endoleaks (TIIIELs), and graft component separations. ResultsA total of 1944 patients met study criteria with 442 (22.8%) inverted iliac limb bifurcates and 1502 (77.2%) standard bifurcates. Patients who received inverted iliac limbs were more likely to have had prior aortic surgery (63.8% vs 28.5%; P < .001). Patients receiving inverted iliac limbs had longer procedure times (265 minutes; interquartile range [IQR], 201-342 minutes vs 241 minutes; IQR, 186-313 minutes; P < .001), more contrast use (89 mL [IQR, 55-135 mL] vs 109 mL [IQR, 75-156 mL]; P < .001), and higher estimated blood loss (250 mL [IQR, 150-500 mL] vs 250 mL [IQR, 110-400 mL]; P = .042). There were no differences in rates of technical success (97.3% vs 96.1%; P = .310), rates of endoleaks upon completion of the case (18.0% vs 21.4%; P = .123), or 30-day mortality rates (1.8% vs 2.5%; P = .466) between patients receiving inverted iliac limb and standard bifurcated components. There were no differences in cumulative survival, freedom from limb ischemia, freedom from aneurysm rupture, and freedom from TIIIELs over the course of 5 years between patients receiving inverted bifurcates and standard bifurcated components. Patients with inverted iliac limb bifurcate components had decreased freedom from reinterventions, TIELs, and TIIELs. After adjustment for potential confounders, the use of an inverted iliac limb was not associated with reinterventions (hazard ratio,1.044; 95% confidence interval, 0.849-1.285; P = .682). There was a total of 2 component separations (0.1%) of the bifurcate component from the fenestrated/branched component over the study period, both of which occurred in the standard bifurcate components. ConclusionsThe use of investigational inverted iliac limb bifurcate components is a safe option with favorable mid-term outcomes in patients who are not anatomical candidates for standard bifurcate components. Patients undergoing investigational inverted iliac limb bifurcate component implantation had decreased freedom from reinterventions, which likely corresponds with the complexity of repair associated with them.

Restoration of respiration in high cervical spinal cord injury via phrenic nerve reinnervation: illustrative case.

Traumatic high cervical spinal cord injury (SCI) can result in a devastating loss of functional respiration, leaving patients permanently dependent on mechanical ventilation. Nerve transfer is a promising reinnervation strategy that has the potential to restore connectivity in paralyzed distal muscles. The spinal accessory nerve (SAN) remains functional in most cases after high cervical SCI and can serve as a donor to reinnervate the phrenic nerve (PN), thereby improving diaphragmatic function. Information regarding thorough physical, electrodiagnostic, and pulmonary assessments to establish candidacy for nerve transfer, as well as the surgical procedure, was summarized with an illustrative case. The patient demonstrated improvement in pulmonary function testing but did not achieve independent respiration. A systematic literature review identified 3 studies with 9 additional patients who had undergone SAN-to-PN transfer. The nerve transfer meaningfully restored diaphragmatic function, improving pulmonary function tests and reducing ventilator dependency. Respiratory dependency significantly impacts the quality of life of patients with a high cervical SCI. The use of the lower SAN motor branch for PN transfer is safe and does not result in a meaningful downgrade in trapezius function. Outcomes following this procedure are promising but heterogeneous, indicating a need for significant innovation and improvement for future therapies. https://thejns.org/doi/10.3171/CASE24236.

Application of Open Panicle Traits in Improving the Filling Characteristics at the Base of Indica Rice Panicles.

Panicle-type structure is an important factor affecting rice yield, and an excellent panicle type has become a key indicator in rice breeding. In this study, the indica rice variety R766, which has an open panicle type, was obtained through natural mutation and hybrid selection. Through analyzing differences in panicle structure, panicle yield, and chemical composition between open panicle rice R766 and conventional panicle rice R2928, we found that the angles of the middle and lower branches in R766 were 186.99% and 135.93% greater than those in R2928, respectively. By comparing the grain-filling characteristics of different panicle positions in the two rice varieties, we found that the grain filling at the middle and lower panicle positions of R2928 was significantly lower, accompanied by an increase in the percentage of empty spikelets. However, in R766, the grain-filling rates in the middle and lower panicle positions were consistent with those in the upper panicle position, with significantly higher rates of grain filling and grain plumpness in the middle and lower panicle positions than in R2928. The empty grain rate at the lower panicle position of R766 was 15.25% lower than that of R2928, and the grain filling was 24.75% higher than that of R2928. Additionally, the variation in the 1000-grain weight of grains at different panicle positions in R766 was relatively small, with decreases of 1.55% and 0.38% in the middle and lower panicle positions, respectively, compared with the upper position, whereas R2928 showed decreases of 5.99% and 7.12% in the 1000-grain weight of grains at the middle and lower panicle positions, respectively, compared with the upper position. The cellulose content in the stems of R766 was 7.51% higher than that of R2928, with no significant difference in the cellulose content in the panicle axis and primary branches compared to R2928. The lignin content of the panicle axis in R766 was 8.03% higher than that in R2928, whereas there was no significant difference between the lignin content of the stems and primary branches. This preliminary study revealed the open panicle characteristics of R766 and the reasons for its high basal grain setting rate. This study provides a reference for promoting this open panicle-type indica rice variety to improve yield and disease resistance in environments with high humidity and low sunlight levels.

Dark State Concentration Dependent Emission and Dynamics of CdSe Nanoplatelet Exciton-Polaritons.

The recent surge of interest in polaritons has prompted fundamental questions about the role of dark states in strong light-matter coupling phenomena. Here, we systematically vary the relative number of dark states by controlling the number of stacked CdSe nanoplatelets confined in a Fabry-Pérot cavity. We find the emission spectrum to change significantly with an increasing number of nanoplatelets, with a gradual shift of the dominant emission intensity from the lower polariton branch to a manifold of dark states. Through accompanying calculations based on a kinetic model, this shift is rationalized by an entropic trapping of excitations by the dark state manifold, while a weak dark state dispersion due to local disorder explains their nonzero emission. Our results point toward the relevance of the dark state concentration to the optical and dynamical properties of cavity-embedded quantum emitters with ramifications for Bose-Einstein condensate formation, polariton lasing, polariton-based quantum transduction schemes, and polariton chemistry.

Accumulation of airborne microplastics on leaves of different tree species in the urban environment

Microplastics (MPs) are omnipresent in the environment and they are linked to ecosystem and human health problems. The atmospheric transport of MPs and the role of tree leaves in MP atmospheric deposition has not been adequately studied. MP concentrations on the leaves of different tree species in urban regions of the Netherlands and Portugal, along with related MP deposition, were investigated in this study. We collected leaves from cedar, eucalyptus, oak, pine and willow trees, together with monthly deposition of particles under the trees and in the open space in Coimbra (Portugal). In Wageningen (the Netherlands), we collected leaves from a fir and a holly tree at different heights above the ground and with dry and wet weather conditions. MPs were extracted through density separation and quantified under a microscope. Polymer types were identified using μ-FTIR. The results showed a higher number of MP particles on the needle-shaped leaves from fir (2.52 ± 2.14 particles·cm−2) and pine (0.5 ± 0.13 particles·cm−2) and significantly lower numbers of MPs per cm2 of leaf area on the bigger leaves from eucalyptus (0.038 ± 0.003 particles·cm−2) and cedar (0.037 ± 0.002 particles·cm−2). All tree leaves seemed to filter airborne MPs, especially the smallest particles. A non-significantly higher number of particles on leaves was detected on lower tree branches and after dry periods. The deposition of MPs under trees was generally higher than in the open space. Our results indicated that part of the MPs retained by the tree leaves floats down to lower branches and to the soil surface. We also saw that different tree species had different capacities to retain particles on their leaves over time. To control the transport of MPs through the atmosphere, it is essential to consider the role of different vegetation types in filtering small particles, especially in cities.

Investigation of nano-confinement effects on asphaltenic crude oil phase behavior in tight and shale reservoirs: Modeling using CPA-EOS

As a result of strong molecule–molecule and molecule–wall interactions, phase behavior in confined fluids differs significantly from that in bulk fluids. Asphaltene precipitation is a challenging issue for both conventional and unconventional (nano-scale) porous media. In this study, a new model based on cubic-plus-association equation of state (CPA-EOS) was developed for studying phase behavior of asphaltenic crude oil and asphaltene precipitation in nanoporous media. The developed model considers confinement phenomena including shift in the critical properties of components, high capillary pressure, and adsorption/desorption of fluid components on rock surface. For this purpose, necessary modifications were performed on both the EOS and phase equilibria calculations. The developed model was then used to analyze two-phase (vapor–liquid) and three-phase (vapor–liquid–asphaltene) behavior in confined systems. Results demonstrated that confinement phenomena shrink the two-phase envelope and shift the critical point of the mixture. It is also shown that instability of asphaltene in the solution is higher in nanoporous media and increases with reducing pore size. Therefore, the amount of precipitated asphaltene in nanoporous media is higher than that in conventional systems. As adsorption of components with higher molecular weights is more than that of low-molecular weight compounds, the crude oil sample is enriched with lighter components and hence, due to adsorption, bubble point pressure increases, upper branch of dew point curve shifts downward and its lower branch shifts upward, and asphaltene instability increases. Neglecting confinement phenomena results in overestimation or underestimation of saturation pressures as well as asphaltene upper and lower onset points and the proposed model can be of high importance in predicting the extent of asphaltene precipitation during natural depletion or solvent injection in tight oil reservoirs.

Holographic thermodynamics of a charged AdS black holes with global monopole

Abstract By regarding the Newton constant GN and cosmological constant Λ as variables, we in this paper study the thermodynamics and phase transition of Reissner-Nordström anti-de Sitter (RN-AdS) black hole with global monopole in the framework of AdS/CFT correspondence. It is found that there are interesting critical phenomena and phase behaviors in the (grand) canonical ensembles of fixed (Q, V, C), (Φ, V, C) and (Q, V, μ). When the other parameters are fixed, the free energy increases with the global monopole increases. In (Q, V, C) ensemble, the range of unstable region increases with the increase of global monopole. In (Φ, V, C) ensemble, when Φ&lt;Φc, the free energy appears two branches, the upper and lower branches correspond to low entropy and high entropy respectively. When (Q, V, μ) is fixed, a new zero-order phase transition occurs in the high-entropy phase and the low-entropy phase at certain μ-dependent temperatures. When μ increases to a certain value, this zero-order phase transition disappears. This certain value is positively related to the magnitude of the global monopole. Finally, we find that p-V criticality does not appear with the change of global monopole. Therefore, it is important to note that the CFT states of charged black holes with global monopole do not correspond to Van der Waals fluids. Finally, we find that charged black holes with global monopoles can better reflect thermodynamic phase transitions and critical phenomena under the AdS/CFT correspondence. By adjusting the change of the global monopole, the thermodynamic phase transition will also change.

Lattice Dynamics of Quasi-2D Perovskites from First Principles.

We present the vibrational properties and phonon dispersion for quasi-2D hybrid organic-inorganic perovskites (BA)2CsPb2I7, (HA)2CsPb2I7, (BA)2(MA)Pb2I7, and (HA)2(MA)Pb2I7 calculated from first principles. Given the highly complex nature of these compounds, we first perform careful benchmarking and convergence testing to identify suitable parameters to describe their structural features and vibrational properties. We find that the inclusion of van der Waals corrections on top of generalized gradient approximation (GGA) exchange-correlation functionals provides the best agreement for the equilibrium structure relative to experimental data. We also investigate the impact of the molecular orientation on the equilibrium structure of these layered perovskite systems. Our results suggest ground state ferroelectric alignment of molecular dipoles in the out-of-plane direction is unlikely and support the assignment of the centrosymmetric space group for the low-temperature phase of (HA)2(MA)Pb2I7. Finally, we compute vibrational properties under the harmonic approximation. We find that stringent energy cut-offs are required to obtain well-converged phonon properties, and once converged, the harmonic approximation can capture key physics for such a large, hybrid inorganic-organic system with vastly different atom types, masses, and interatomic interactions. We discuss the obtained phonon modes and dispersion behavior in the context of known properties for bulk 3D perovskites and ligand molecular crystals. While many vibrational properties are inherited from the parent systems, we also observe unique coupled vibrations that cannot be associated with vibrations of the pure constituent perovskite and ligand subphases. Energy dispersion of the low energy phonon branches primarily occurs in the in-plane direction and within the perovskite subphase and arises from bending and breathing modes of the equatorial Pb-I network within the perovskite octahedral plane. The analysis herein provides the foundation for future investigations on this class of materials, such as exciton-phonon coupling, phase transitions, and general temperature-dependent properties.

Impact of the hot inner crust on compact stars at finite temperature

We conducted a study on the thermal properties of stellar matter with the nuclear energy density functional BCPM. This functional is based on microscopic Brueckner–Hartree–Fock calculations and has demonstrated success in describing cold neutron stars. To enhance its applicability in astrophysics, we extended the BCPM equation of state to finite temperature for β-stable neutrino-free matter, taking into consideration the hot inner crust. Such an equation of state holds significant importance for hot compact objects, particularly those resulting from a binary neutron star merger event. Our exploration has shown that with increasing temperature, there is a fast decrease in the crust-core transition density, suggesting that for hot stars it is not realistic to assume a fixed value of this density. The microscopic calculations also reveal that the presence of nuclear clusters persists up to T = 7.21 MeV, identified as the limiting temperature of the crust. Above this threshold, the manifestation of clusters is not anticipated. Below this temperature, clusters within the inner crust are surrounded by uniform matter with varying densities, allowing for the distinction between the upper and lower transition density branches. Moreover, we computed mass–radius relations of neutron stars, assuming an isothermal profile for β-stable neutron star matter at various temperature values. Our findings highlight the significant influence of the hot inner crust on the mass–radius relationship, leading to the formation of larger and more inflated neutron stars. Consequently, under our prescription, the final outcome is a unified equation of state at finite temperature.

Spin orbit coupling enhanced thermionic cooling in two-dimensional semiconductor structures

We theoretically investigate the effect of Rashba spin–orbit coupling (RSO) on thermionics properties of two-dimensional semiconductor. Due to the hybridization of parabolic and linear energy dispersion, the thermal energy equipartition is modified. The thermionic emission from the lower spin branch is enhanced and that from the upper spin branch is reduced. For a double quantum well cooling structure under lower doping, the net heat transported through the structure is enhanced by RSO. The coefficient of performance (COP) is improved by about 20% in the low bias regime and around 3% in the high bias regime. Since the RSO can be further tuned by an applied field, the COP can be further optimized.

Numerical simulation of flow around two side-by-side elliptic cylinders at different Reynolds numbers

The study of the flow around the parallel elliptic cylinder is important to the analysis of the shedding vortex, lift, and drag characteristics in practical engineering, while relevant research is limited. In this paper, the flow around two side-by-side elliptic cylinders at different Reynolds numbers (Re=100,3900,105) is numerically simulated, and the flow characteristics at different gap-ratios and aspect-ratios are analyzed. By comparing the shedding characteristics of the vortexes and the lift (C_(L,AMP) and C _L)and drag (C _D) characteristics of the structure, we found that the vortex appears as a single elliptic cylinder at different Reynolds numbers and when G is small. Then, with the increase of gap-ratio G, vortexes gradually occur at the gap. Furthermore, C _D, C_(L,AMP)and C _L show a decreasing trend. With the increase of aspect-ratio A, the size of the vortices in the upper and lower branches decreases at different Reynolds numbers, while the vortexes in the middle branch show different characteristics at different Reynolds numbers.C _Ddecreases at different Reynolds numbers as A increases. At Re=100, with the increase of A, C_(L,AMP) decreases, while C _L increases. At Re=3900 and Re=105, The curves of C_(L,AMP) and C _Lshow fluctuations.

Automatic segmentation of spine x-ray images based on multiscale feature enhancement network.

Automatic segmentation of vertebrae in spinal x-ray images is crucial for clinical diagnosis, case analysis, and surgical planning of spinal lesions. However, due to the inherent characteristics of x-ray images, including low contrast, high noise, and uneven grey scale, it remains a critical and challenging problem in computer-aided spine image analysis and disease diagnosis applications. In this paper, a Multiscale Feature Enhancement Network (MFENet), is proposed for segmenting whole spinal x-ray images, to aid doctors in diagnosing spinal-related diseases. To enhance feature extraction, the network incorporates a Dual-branch Feature Extraction Module (DFEM) and a Semantic Aggregation Module (SAM). The DFEM has a parallel dual-branch structure. The upper branch utilizes multiscale convolutional kernels to extract features from images. Employing convolutional kernels of different sizes helps capture details and structural information at different scales. The lower branch incorporates attention mechanisms to further optimize feature representation. By modeling the feature maps spatially and across channels, the network becomes more focused on key feature regions and suppresses task-irrelevant information. The SAM leverages contextual semantic information to compensate for details lost during pooling and convolution operations. It integrates high-level feature information from different scales to reduce segmentation result discontinuity. In addition, a hybrid loss function is employed to enhance the network's feature extraction capability. In this study, we conducted a multitude of experiments utilizing dataset provided by the Spine Surgery Department of Henan Provincial People's Hospital. The experimental results indicate that our proposed MFENet demonstrates superior segmentation performance in spinal segmentation on x-ray images compared to other advanced methods, achieving 92.61±0.431 for MIoU, 92.42±0.329 for DSC, and 99.51±0.037 for Global_accuracy. Our model is able to more effectively learn and extract global contextual semantic information, significantly improving spinal segmentation performance, further aiding doctors in analyzing patient conditions.

On the energetic particle-induced geodesic acoustic modes with finite-orbit-width effects

This study presents an analytical investigation of energetic particle-induced geodesic acoustic modes (EGAMs) within a gyro-kinetic model, incorporating finite-orbit-width (FOW) effects up to the second order. The inclusion of second-order FOW effects introduces two distinct types of energetic particle-wave resonances, occurring at ω=ωth and ω=2ωth , respectively, where ωth denotes the transit frequency of energetic particles (EPs). It is found that two unstable EGAM branches coexist: a low frequency branch (LFB) characterized by 0<ωLFB<ωt,maxh , and a high frequency branch (HFB) marked by ωt,maxh<ωHFB<2ωt,maxh . The instability of LFB primarily arises from the resonance ω=ωth , mainly introduced by first-order FOW effects. As a result, the instability of LFB always exists regardless of the presence or absence of second-order FOW effects, and is barely modified by these effects. In contrast, the instability of HFB is exclusively attributed to the resonance ω=2ωth induced by second-order FOW effects. Consequently, the HFB exhibits instability in the presence of these effects.

Computed tomography mucus plugs and airway tree structure in patients with chronic obstructive pulmonary disease: Associations with airflow limitation, health-related independence and mortality.

Mucus plugs and underlying airway tree structure can affect airflow limitation and prognosis in patients with chronic obstructive pulmonary disease (COPD), but their relative roles are unclear. This study used two COPD cohorts to examine whether mucus plugs on computed tomography (CT) were associated with airflow limitation and clinical outcomes independent of other airway structural changes and emphysema. Based on visual CT assessment, patients with mucus plugs in 0, 1-2 and ≥3 lung segments were assigned to no-, low- and high-mucus groups. Loss of health-related independence and mortality were prospectively recorded for 3 and 10 years in the Kyoto-Himeji and Hokkaido cohorts, respectively. The percentages of the wall area of the central airways (WA%), total airway count (TAC) and emphysema were quantified on CT. Of 199 and 96 patients in the Kyoto-Himeji and Hokkaido cohorts, 34% and 30%, respectively, had high mucus scores. In both cohorts, TAC was lower in the high-mucus group than in the no-mucus group, whereas their emphysema severity did not differ. High mucus score and low TAC were independently associated with airflow limitation after adjustment for WA% and emphysema. In multivariable models adjusted for WA% and emphysema, TAC, rather than mucus score, was associated with a greater rate of loss of independence, whereas high mucus score, rather than TAC, was associated with increased mortality. Mucus plugs and lower airway branch count on CT had distinct roles in airflow limitation, health-related independence and mortality in patients with COPD.

Viscous fluid flow and heat transfer past a permeable wall jet with convective boundary conditions

PurposeThe steady laminar wall jet flow over a stretching/shrinking surface in the presence of lateral suction or injection with a convective boundary condition is considered.Design/methodology/approachThe partial differential equations for mass, momentum and energy conservation are changed to the system of ordinary differential equations through similarity solution transformations. Solutions, both numerical and asymptotic, to these similarity equations are found in some new ranges of parameters in the governing equations.FindingsThe equations are solved both asymptotically and numerically for a range of the transpiration parameter S and the flow parameter λ given in Mahros et al. (2023), thus greatly extending the range of these previous solutions. Asymptotic solutions for both large and small values of the Prandtl number σ are derived, showing good agreement with additional numerical integrations. It should be noted that in Mahros et al. (2023), only the case when σ=1 was treated. A solution for large λ when S=1 is obtained, showing a different asymptotic form to the case when S>0 in Mahros et al. (2023). Multiple solutions were seen by them for S<0 and the nature of the lower solution branch as S→0 from below is discussed. The question as to whether the lower branch solutions join as λ>0 when S<0 is resolved through obtaining an asymptotic solution λ small.Originality/valueThe accuracy of the solutions has been checked through a detailed comparison between the solutions obtained numerically and analytically, where excellent agreement has been found. This study is important for scientists working in the area of jet flows to become familiar with the flow properties and behaviour of jets.