simulation model

We report on an optical amplification and energy threshold of the two most prominent emission lines, 391.4 and 427.8 nm, of the cavity-less lasing of nitrogen ions pumped by femtosecond laser pulses. It was found that the two transitions both show optical amplification under a low gas pressure condition, while the 391.4 nm emission is barely amplified under high gas pressure. Moreover, the 427.8 nm emission presents a significant lower pump laser energy threshold and a larger gain factor than the 391...

As a complex anisotropic medium, variation in birefringence within biological tissues is closely associated with numerous physiological behaviors and phenomena. In this Letter, we propose a polarization feature fusion method and corresponding polarimetric parameters, which exhibit excellent performance of capturing the birefringence dynamic variation process in complex anisotropic media. By employing the feature fusion method, we combine and transform polarization basis parameters (PBPs) to derive fused polarization feature parameters (FPPs) with explicit expressions...

PURPOSE/AIM: Robotic-assisted techniques have the potential to revolutionize dental implantology by offering enhanced precision, accuracy, and clinical outcomes compared to computer-assisted implant placement techniques. This study aimed to evaluate the accuracy of dental implant placement using robot-assisted implant surgery in vitro settings. METHODS: An unrestricted search of indexed databases along with a manual search was performed up to March 2024. In vitro, studies comparing the positioning accuracy of robotic systems in dental implant placement of planned pre-operative coordinates and postoperative outcomes in phantom and simulated models were included...

Marine and terrestrial biogeochemical models are key components of the Earth System Models (ESMs) used to project future environmental changes. However, their slow adjustment time also hinders effective use of ESMs because of the enormous computational resources required to integrate them to a pre-industrial equilibrium. Here, a solution to this "spin-up" problem based on "sequence acceleration", is shown to accelerate equilibration of state-of-the-art marine biogeochemical models by over an order of magnitude...

Probabilistic seismic hazard assessments (PSHAs) provide the scientific basis for building codes to reduce damage from earthquakes. Despite their substantial impact, little is known about how well PSHA predicts actual shaking. Recent PSHA for California, Japan, Italy, Nepal, and France appear to consistently overpredict historically observed earthquake shaking intensities. Numerical simulations show that observed shaking is equally likely to be above or below predictions. This result from independently developed models and datasets in different countries and tectonic settings indicates possible systematic bias in the hazard models, the observations, or both...

How breathing is generated by the preBötzinger complex (preBötC) remains divided between two ideological frameworks, and a persistent sodium current (INaP ) lies at the heart of this debate. Although INaP is widely expressed, the pacemaker hypothesis considers it essential because it endows a small subset of neurons with intrinsic bursting or "pacemaker" activity. In contrast, burstlet theory considers INaP dispensable because rhythm emerges from "preinspiratory" spiking activity driven by feed-forward network interactions...

BACKGROUND: Low hip bone mineral density (BMD) in patients who undergo total hip arthroplasty (THA) increases the risk of periprosthetic fractures, implant instability, and other complications. Recently, emphasis has been placed on bone health optimization: treating low BMD prior to a planned orthopaedic implant procedure in an effort to normalize BMD and reduce the potential risk of future complications. Abaloparatide is a U.S. Food and Drug Administration-approved osteoanabolic agent for men and postmenopausal women with osteoporosis and a candidate drug for bone health optimization that, in addition to benefits at the spine, increases hip BMD and reduces nonvertebral fracture risk...

Histograms are frequently used to perform a preliminary study of data, such as finding outliers and determining the distribution's shape. It is common knowledge that choosing an appropriate number of bins is crucial to revealing the right information. It's also well known that using bins of different widths, which called unequal bin width, is preferable to using bins of equal width if the bin width is selected carefully. However this is a much difficult issue. In this research, a novel approach to AIC for histograms with unequal bin widths was proposed...

Stomata are pores on plant aerial surfaces, each bordered by a pair of guard cells. They control gas exchange vital for plant survival. Understanding how guard cells respond to environmental signals such as atmospheric carbon dioxide (CO2) levels is not only insightful to fundamental biology but also relevant to real-world issues of crop productivity under global climate change. In the past decade, multiple important signaling elements for stomatal closure induced by elevated CO2 have been identified. Yet, there is no comprehensive understanding of high CO2-induced stomatal closure...

Intermittent oil-water wetting can have a significant effect on the internal corrosion of steel pipelines. This paper presents a combined experimental and molecular modeling study of several influential factors on the surface properties and corrosion behavior of mild steel in CO2 environments. The influence of different model oils (LVT-200 and Aromatic-200) and select surface-active compounds (myristic acid, cyclohexane butyric acid, and oleic acid) on the corrosion behavior of carbon steel during intermittent oil-water wetting was determined by measuring the corrosion rate after intermittent wetting cycles...

A comprehensive understanding of the full volatility spectrum of organic oxidation products from the benzene series precursors is important to quantify the air quality and climate effects of secondary organic aerosol (SOA) and new particle formation (NPF). However, current models fail to capture the full volatility spectrum due to the absence of important reaction pathways. Here, we develop a novel unified model framework, the integrated two-dimensional volatility basis set (I2D-VBS), to simulate the full volatility spectrum of products from benzene series precursors by simultaneously representing first-generational oxidation, multigenerational aging, autoxidation, dimerization, nitrate formation, etc...

CONTEXT: Density functional theory (DFT) calculations are carried out on pure and doped rutile TiO <mml:math xmlns:mml="https://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow/> <mml:mn>2</mml:mn></mml:msub> </mml:math> . The bandgap (E <mml:math xmlns:mml="https://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow/> <mml:mi>g</mml:mi></mml:msub> </mml:math> ) for pristine, S-doped, Fe-doped, and Fe/S co-doped materials is direct, with values of 2...

Cognitive diagnosis is a crucial element of intelligent education that aims to assess the proficiency of specific skills or traits in students at a refined level and provide insights into their strengths and weaknesses for personalized learning. Researchers have developed numerous cognitive diagnostic models. However, previous studies indicate that diagnostic accuracy can be significantly influenced by the appropriateness of the model and the sample size. Thus, designing a general model that can adapt to different assumptions and sample sizes remains a considerable challenge...

Most water-borne disease models ignore the advection of water flows in order to simplify the mathematical analysis and numerical computation. However, advection can play an important role in determining the disease transmission dynamics. In this paper, we investigate the long-term dynamics of a periodic reaction-advection-diffusion schistosomiasis model and explore the joint impact of advection, seasonality and spatial heterogeneity on the transmission of the disease. We derive the basic reproduction number <mml:math xmlns:mml="https://www...

PURPOSE: Elevated intraocular pressure (IOP) is thought to cause lamina cribrosa (LC) blood vessel distortions and potentially collapse, adversely affecting LC hemodynamics, reducing oxygenation, and triggering, or contributing to, glaucomatous neuropathy. We assessed the robustness of LC perfusion and oxygenation to vessel collapses. METHODS: From histology, we reconstructed three-dimensional eye-specific LC vessel networks of two healthy monkey eyes. We used numerical simulations to estimate LC perfusion and from this the oxygenation...

BACKGROUND AND OBJECTIVES: The influence of the intracranial pressure field must be discussed with the development of a single-element transducer for low-intensity transcranial focused ultrasound because the skull plays a significant role in blocking and dispersing ultrasound wave propagation. Ultrasound propagation is mainly affected by the structure and acoustic properties of the skull; thus, we aimed to investigate the impact of simplifying the acoustic properties of the skull on the simulation of the transcranial pressure field to present guidance for efficient skull modeling in full-wave simulations...

It is critical to understand the impact of significant physiological changes during pregnancy on the extent of maternal and fetal drug exposure. Fostemsavir (FTR) is a prodrug of temsavir (TMR) and is approved in combination with other antiretrovirals for multi-drug-resistant human immunodeficiency virus (HIV) infections. This physiologically based pharmacokinetic model (PBPK) study was used to estimate TMR PK in pregnant populations during each trimester of pregnancy to inform FTR dosing. A PBPK model was developed and validated for TMR using PK data collected following intravenous TMR and oral FTR dosing (immediate-release and extended-release tablets) in healthy volunteers...

BACKGROUND: Aspirin, an effective, low-cost pharmaceutical, can significantly reduce mortality if used promptly after acute myocardial infarction (AMI). However, many AMI survivors do not receive aspirin within a few hours of symptom onset. Our aim was to quantify the mortality benefit of self-administering aspirin at chest pain onset, considering the increased risk of bleeding and costs associated with widespread use. METHODS AND RESULTS: We developed a population simulation model to determine the impact of self-administering 325 mg aspirin within 4 hours of severe chest pain onset...

Despite being among the most common medical procedures, needle insertions suffer from a high error rate. Impedance measurements using electrode-equipped needles offer promise for improved tissue targeting and reduced errors. Impedance visualization usually requires an extensive pre-measured impedance dataset for tissue differentiation and knowledge of the electric fields contributing to the resulting impedances. This work presents two finite element simulation approaches for both problems. The first approach describes the generation of a multitude of impedances with Monte Carlo simulations for both, homogeneous and inhomogeneous tissue to circumvent the need to rely on previously measured data...

OBJECTIVE: Designing physiologically adequate microvascular trees is of crucial relevance for bioengineering functional tissues and organs. Yet, currently available methods are poorly suited to replicate the morphological and topological heterogeneity of real microvascular trees because the parameters used to control tree generation are too simplistic to mimic results of the complex angiogenetic and structural adaptation processes in vivo. METHODS: We propose a method to overcome this limitation by integrating a conditional deep convolutional generative adversarial network (cDCGAN) with a local fractal dimension-oriented constrained constructive optimization (LFDO-CCO) strategy...