Bimodal Research Articles

Cloud Characteristics in South China Using Ka-Band Millimeter Cloud Radar Datasets

In this study, we investigate the seasonal and diurnal variations in cloud occurrence frequency, as well as cloud vertical structure (CVS) characteristics under different seasons and precipitation intensities over the Guangzhou region in South China, based on the analysis of millimeter-wave cloud radar (MMCR) and ground automatic weather station rainfall observations from May 2019 to August 2021. The results showed that the occurrence frequency of clouds exhibits a bimodal distribution throughout the year, with peaks in March to June and October, reaching its highest occurrence in May at approximately 80% and its lowest from December to February at around 40%. Additionally, there are distinct diurnal variations in occurrence frequency, with the lowest rates occurring around 0005 LST, rapidly increasing after 0006 LST, and peaking during the afternoon to evening hours. Cloud top height (CTH) shows bimodal distributions during the pre-flood and post-flood seasons. The most frequently occurring range of CTH during the pre-flood season is below 3 km, accounting for approximately 43%, while during the post-flood season, it ranges from 11 to 14 km, constituting about 37%. For precipitation clouds, CTH can extend beyond 12 km, with the radar reflectivity decreasing gradually with increasing height. The highest frequencies of radar echoes are observed below 2 km and between 4 and 7 km, exhibiting clear diurnal variations, with echoes mainly below 2 km and between 4 to 6 km during the early morning, intensifying and shifting to higher altitudes during the day and reaching their maximum below 4 km during the afternoon to nighttime hours, while both the frequency and intensity increase in the height range of 4 to 12 km. Vertical profiles of radar reflectivity and cloud ice/liquid water content (IWC/LWC) exhibit similar trends under different precipitation intensities. The main differences are observed below 4 km, where both radar reflectivity and IWC/LWC generally increase with increasing precipitation intensity. These findings contribute to a better understanding of cloud characteristics in the South China region, enhance the accuracy of model simulations, and provide a scientific basis for accurate forecasting and warning of meteorological disasters.

Two Ubiquitous Radiative States Observed across the High Latitudes

Abstract Previous studies have shown the Arctic exhibits two preferred radiative states, one that is regarded as “radiatively opaque” and the other as “radiatively clear”; this presents as bimodality in the surface longwave flux distributions. How frequently these two states occur and what causes them to persist has significant implications for the polar climate. Furthermore, in the presence of multimodality, evaluating models based solely on their ability to resolve the mean and variance of a distribution can lead to a poor representation of the physical evolution of our climate. This study takes a holistic view of this bimodal behavior, seeking to understand to what degree the high latitudes of both hemispheres reside in distinct radiative states. Even when separated into climatologically distinct subregions, many polar regions exhibit bimodality in their longwave flux distributions not observed at lower latitudes, suggesting that the existence of these two states is both common in and unique to polar regions. Bimodality arises due to a tendency for the atmosphere to alternate between transmissive or opaque clouds, with surface longwave radiative effects of approximately 0 and 75 W m−2 (relative to clear-sky values), respectively. Clouds need not contain liquid to lead to the opaque state, as is typically assumed. The presence of solely ice clouds can cause bimodality to arise in downwelling longwave flux distributions. While some regions do not explicitly exhibit multimodal surface longwave radiation distributions, it is found that similar cloud states exist but in disproportionate frequencies. Significance Statement Radiation plays an important role in shaping the Arctic and Antarctic climates. Several Arctic expeditions have found that certain regions flip between having a very large energy deficit (“transmissive”) to relatively small energy deficit (“opaque”). The former allows for surface cooling and promotes the formation of ice, while the latter hinders such behavior. This study utilizes satellite observations to understand if this behavior is consistent across the Arctic and Antarctic. Understanding the frequencies of these two states is increasingly important within the context of our rapidly changing climate, and by uncovering the fundamental processes which lead to them, we may be able to model how they will change in the future.

Impacts of altitude on plant green leaf, fresh litter, and soil stoichiometry in subtropical forests

BackgroundEcological stoichiometric characteristics of carbon (C), nitrogen (N), phosphorus (P), and potassium (K) serve as crucial indicators of nutrient cycling and limitation in terrestrial ecosystems. However, our current understanding of stoichiometric characteristics in subtropical forests and their response to different climate conditions is still limited.MethodsWe selected six altitudes ranging from 700 m to 1,200 m to simulate different climate conditions of an evergreen broadleaf forest in Wuyi Mountain, Fujian Province, China. We investigated C, N, P, and K stoichiometry and homeostasis in the green leaves, newly senesced leaf litter (fresh litter), and soil of this forest.ResultsLeaf P and K levels showed a decline with increasing altitude. Notably, the stoichiometric ratios in different components exhibited a bimodal distribution along the altitudinal gradient. Additionally, a decline trend of N resorption efficiencies was observed as altitude increased. Moreover, weak homeostasis was observed in P and K in green leaves. These findings highlighted the significant impact of altitude on the stoichiometry in evergreen broadleaf forest. This study also contributed to our understanding of the nutrient cycling mechanism and plant growth strategies of evergreen forests under different climate conditions.

Freshwater trematodes differ from marine trematodes in patterns connected with division of labor.

Prior research suggests that trematode rediae, a developmental stage of trematode parasites that reproduce clonally within a snail host, show evidence of division of labor (DOL). Single-species infections often have two morphologically distinct groups: small rediae, the 'soldiers', are active, aggressive, and do not appear to reproduce; large rediae, the 'reproductives', are larger, sluggish, and full of offspring. Most data supporting DOL come from trematodes infecting marine snails, while data from freshwater trematodes are more limited and generally do not supported DOL. The shorter lifespan typical of freshwater snails may partially explain this difference: defending a short-lived host at the expense of reproduction likely provides few advantages. Here, we present data from sixty-one colonies spanning twenty species of freshwater trematode exploring morphological and behavioral patterns commonly reported from marine trematodes believed to have DOL. Trematode rediae were obtained from sixty-one infected snails collected in central Vermont, USA. A portion of the COI gene was sequenced to make tentative species identifications ('COI species'). Samples of rediae were photographed, observed, and measured to look for DOL-associated patterns including a bimodal size distribution, absence of embryos in small rediae, and pronounced appendages and enlarged pharynges (mouthparts) in small rediae. Additional rediae were used to compare activity levels and likelihood to attack heterospecific trematodes in large vs. small rediae. Many of the tests for DOL-associated patterns showed mixed results, even among colonies of the same COI species. However, we note a few consistent patterns. First, small rediae of most colonies appeared capable of reproduction, and we saw no indication (admittedly based on a small sample size and possibly insufficient attack trial methodology) that small rediae were more active or aggressive. This differs from patterns reported from most marine trematodes. Second, the small rediae of most colonies had larger pharynges relative to their body size than large rediae, consistent with marine trematodes. We also observed that colonies of three sampled COI species appear to produce a group of large rediae that have distinctly large pharynges. We conclude that these freshwater species likely do not have a group of specialized non-reproductive soldiers because small rediae of at least some colonies in almost every species do appear to produce embryos. We cannot rule out the possibility that small rediae act as a temporary soldier caste. We are intrigued by the presence of rediae with enlarged pharynges in some species and propose that they may serve an adaptive role, possibly similar to the defensive role of small 'soldier' rediae of marine trematodes. Large-pharynx rediae have been documented in other species previously, and we encourage future efforts to study these large-pharynx rediae.

Origin of a polymict, mega‐clast‐bearing impact breccia in the crater floor of Wetumpka Impact Structure, Elmore County, Alabama: Insights from surface outcrops and a drill core

ABSTRACTWetumpka impact structure is a Late Cretaceous, marine‐target impact crater of about 5 km diameter. The apparent crater rim is mostly made of crystalline local basement, and the apparent crater floor consists of a mixed sediments of target lithology. These sediments are the provenance of the crater‐filling impactite sands, overlying trans‐crater slide unit, and the capping polymict impact breccia deposit, often referred to by previous workers as “central polymict breccia.” The unit has been known to contain elongated mega‐clasts of up to tens of meters in size. This study attempted to understand the mode of emplacement of this polymict breccia, which occurs in some places on the apparent crater floor and resembles a polymict proximal ejecta deposit. This work also reports the first documentation of rare, potential impact spherules in the polymict impact breccia, interpreted to be a part of distal ejecta. The presence of large, decimeter‐sized clasts in the breccia can be best explained by the movement of overturned rim flap forming part of proximal ejecta from the crater rim to the apparent crater floor during early modification stage of impact cratering. Our work highlights the bimodal clast size distribution of the polymict breccia, and so we propose that the term “mega‐clast‐bearing impact breccia” be used for this unit. We attribute a generally steep orientation of the decameter sized clasts to primary imbrication during emplacement. The emplacement of this breccia is interpreted as associated with the ejecta emplacement process that occurred before the return of marine resurge.

Deterioration of volcanic tuffs from rock dwellings in Brhlovce (Slovakia) induced by freeze-thaw cycling studied by non-destructive tests and µCT visualization

The aim of this paper is to evaluate the effect of freeze-thaw-induced weathering of volcanic tuffs from the rock dwellings in the village of Brhlovce (Slovakia) based on a non-destructive and experimental study of tuff pore space properties. Traditional techniques for characterization of the porosity and pore size distribution and new experimental techniques like spontaneous imbibition (pore interconnection) or indicative rock pore structure method (pore size distribution) were compared with pore network models acquired by X-ray computed microtomography before and after freeze-thaw cycling in a custom-built thermodilatometer VLAP04. The results offer insight into how frost weathering altered the pore network of volcanic tuffs. Brhlovce tuffs are highly susceptible to frost damage due to their high porosity, pore interconnectivity, and bimodal pore size distribution pattern, where nanometric-sized micropores predominate over larger micrometric-sized capillary pores. Poromechanical principles were applied to confirm that ice crystallization initiates in well-connected micropores with a corresponding crystallization pressure below 10 MPa. After undergoing 100 freeze-thaw cycles with temperature oscillations ranging from − 10 to 10 °C, there was a significant increase in total porosity, pore interconnectivity, and rock permeability. Additionally, the pore size distribution was altered. These parameters influence the transport of fluids and the moisture regime in rock masses, which can serve as a precursor to physical and chemical weathering processes

Investigating direct current potentials that affect native protein conformation during trapped ion mobility spectrometry-mass spectrometry.

Trapped ion mobility spectrometry-time-of-flight mass spectrometry (TIMS-TOFMS) has emerged as a tool to study protein conformational states. In TIMS, gas-phase ions are guided across the IM stages by applying direct current (DC) potentials (D1-6), which, however, might induce changes in protein structures through collisional activation. To define conditions for native protein analysis, we evaluated the influence of these DC potentials using the metalloenzyme bovine carbonic anhydrase (BCA) as primary test compound. The variation of DC potentials did not change BCA-ion charge and heme content but affected (relative) charge-state intensities and adduct retention. Constructed extracted-ion mobilograms and corresponding collisional cross-section (CCS) profiles gave useful insights in (alterations of) protein conformational state. For BCA, the D3 and D6 potential (which are applied between the deflection transfer and funnel 1 [F1] and the accumulation exit and the start of the ramp, respectively) had most profound effects, showing multimodal CCS distributions at higher potentials indicating gradual unfolding. The other DC potentials only marginally altered the CCS profiles of BCA. To allow for more general conclusions, five additional proteins of diverse molecular weight and conformational stability were analyzed, and for the main protein charge states, CCS profiles were constructed. Principal component analysis (PCA) of the obtained data showed that D1 and D3 exhibit the highest degree of correlation with the ratio of folded and unfolded protein (F/U) as extracted from the mobilograms obtained per set D potential. The correlation of D6 with F/U and protein charge were similar, and D2, D4, and D5 showed an inverse correlation with F/U but were correlated with protein charge. Although DC boundary values for induced conformational changes appeared protein dependent, a set of DC values could be determined, which assured native analysis of most proteins.

Characterization of stratospheric particle size distribution uncertainties using SAGE II and SAGE III/ISS extinction spectra

Abstract. A new algorithm was developed to infer particle size distribution parameters from the Stratospheric Aerosol and Gas Experiment II (SAGE II) and SAGE III on the International Space Station (SAGE III/ISS) extinction spectra using a lookup table (LUT) approach. Here, the SAGE-based extinction ratios were matched to LUT values, and, using these matches, weighted statistics were calculated to infer the median particle size distribution values and higher-moment parameters as well as quantify the uncertainty in these estimates. This was carried out by solving for both single-mode and bimodal lognormal distributions. The work presented herein falls under two general headings: (1) a theoretical study was carried out to determine the accuracy of this methodology, and (2) the solution algorithm was applied to the SAGE II and SAGE III/ISS records with a brief case study analysis of the 2022 Hunga Tonga eruption. This methodology was demonstrated to be ≈ 25 % accurate for mode radius and has a minor dependence on particle composition. While bimodal solutions were obtained from this algorithm, we provide a conclusive demonstration of how and why these estimates are inherently unstable using SAGE III/ISS extinction spectra alone. Finally, we demonstrated how the Hunga Tonga aerosol plume evolved in regard to both size and transport over 18 months after the 2022 Hunga Tonga eruption. The particle size distribution (PSD) estimates, higher-moment parameters, and uncertainties are new products within the SAGE III/ISS Level 2 (L2) products, are currently available for download, and will be merged into the main SAGE III/ISS release products in a subsequent L2 release.

A New Shear Strength Model with Structural Damage for Red Clay in the Qinghai-Tibetan Plateau

Under the background of climate warming in the Qinghai-Tibetan Plateau (QTP), frequent freeze–thaw cycling (FTC) brings about great geological disasters such as subgrade failure, landslides, and mudslides, which is closely related to the strength reduction caused by the structural damage of soils. In this study, to explore the association between macro shear strength and microstructure evolution of soils subjected to FTC, the red clay distributed widely in the QTP was chosen and used to conduct a series of triaxial shear and nuclear magnetic resonance (NMR) tests in the range of 1 to 7 FTCs. Triaxial shear test results reveal that the shear strength reduction of specimens mainly occurs within five FTCs, and the trend of peak deviator stress with increasing FTCs can be described in three stages: rapid descent (FTCs less than three), slow descent (FTCs between three and five), and stabilization (FTCs greater than five). NMR tests show that the T2 spectrum curves exhibit a distinct bimodal distribution characteristic, corresponding to macropores and micropores. Part of the micropores gradually develop into macropores with increasing FTCs, especially within five FTCs. The increase in macropores proportion leads to a loose soil structure, which is consistent with the deterioration of the shear strength of specimens. Finally, based on the experimental results and classical Mohr–Coulomb theory, a new shear strength model with structural damage for red clay has been proposed by introducing a damage factor expressed by T2 spectral area.

EBSD characterization of graphene nano sheet reinforced Sn–Ag solder alloy composites

This research explores the effects of incorporating Graphene Nano Sheets (GNS) on the microstructural characteristics and mechanical behavior of Sn–Ag solder alloys. The research was driven by the need for environmentally friendly, lead-free solder alloys with enhanced mechanical and thermal properties. The methodology involved incorporating graphene into the Sn–Ag alloy through stir casting, followed by a series of surface preparation techniques. The composite samples were then examined using EBSD to analyze crystallographic orientations and SEM/EDS for surface morphology and elemental composition. XRD provided insights into phase transformations and structural changes. Key findings reveal that the addition of GNS significantly refines the grain structure of the Sn–Ag alloy, leading to a bimodal grain size distribution. This refinement is attributed to the role of GNS as a nucleation site during solidification. Moreover, the study demonstrates a pronounced alteration in the texture of the material, with an increase in low-angle grain boundaries post-GNS addition. This texture change is indicative of enhanced mechanical properties. The results also show a shift in the orientation distribution function (ODF), suggesting a stronger crystallographic orientation due to GNS. These findings suggest that GNS incorporation could lead to improved mechanical and thermal properties in Sn–Ag solder, making them suitable for high-performance electronic applications. The study concludes that GNS not only serves as an effective reinforcement in Sn–Ag solder alloys but also significantly alters their microstructural and textural characteristics, contributing to the alloy's potential application in environmentally conscious electronic manufacturing.

Synthesis and Characterization of Enhanced Proton-Conducting Nafion<sup>® </sup>117- Silica Composite Membranes for Fuel Cell Applications

Nafion®/silica nanocomposite membranes were prepared by impregnation method from Nafion® 117 and sol-gel pre-synthesized n-octadecyl-trimethoxy silane (C18TMS) coated silica nanoparticles. The scanning electron microscope (SEM) of pristine silica particles displayed monodispersed nanospheres with diameters ranging from 150-350 nm; while Brunauer-Emmett-Teller (BET) analysis presented 760 m2/g BET surface area, a micropore-mesopore bimodal distribution of micropore systems with respective pore volume at 14.6 Å and 17.0 Å (2.01 x 10-3 cm3/g.Å), as well as the prolific mesopores centered at 29.5 Å (5.64 x 10-2 cm3/g.Å). Characterization of Nafion® 117 based membranes on SEM, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and x-ray diffraction (XRD), and tensile stress exhibited varying surface morphology with silica loadings, structural interaction between membrane support and the ion exchanger, thermal stabilities (up to 330 °C), crystalline nature, and reasonable mechanical stability of nanocomposite membranes. The maximum water uptake (44.8 %) and proton conductivity of (1.14 x10-2 S/cm) were obtained on low Nafion®/SiO2 (5%) loaded membrane. While both composite membranes displayed the improved reduction in methanol permeability, 2.43x10-07 cm2/s at 80 °C was obtained with high Nafion®/SiO2 (10%) loading. Improved water uptake and proton conductivity substantiate the high ion exchange capacity (IEC) of 1.81 meq.g-1 when compared to IEC of 0.93 meq.g-1 [pristine Nafion®] and 1.46 meq.g-1 [Nafion®/SiO2 (10%)]. The increase in IEC value may be due to the high acid functionalization of additional sulfonic acid groups surrounded by hydrophilic segments of nanosilica, which improves the properties of the membrane. The high proton conductivity coupled with great water retention capabilities indicated that the Nafion®/SiO2 nanocomposite membranes could be utilized as proton exchange membranes for medium temperature methanol fuel cells. Keywords: Fuel cells; nanocomposite membrane; SiO2 nanofillers; methanol permeability; ion exchange capacity

Sensitivity Analysis of the Square Cup Forming Process Using PAWN and Sobol Indices

This study investigates the sensitivity of the square cup forming process. It analyses how the uncertainties in the material properties, friction and process conditions affect the results of the square cup, such as equivalent plastic strain, geometry change, thickness reduction, punch force and springback. The cup flange and the die curvature region are identified as highly affected areas, while the cup bottom is least affected by the uncertainties. Two sensitivity analysis techniques, PAWN and Sobol indices, are compared. In particular, the study shows that PAWN indices require a significantly smaller number of simulations than Sobol indices, making them a more efficient choice for sensitivity analysis. While both PAWN and Sobol indices generally give comparable results, discrepancies arise in the analysis of springback, where PAWN indices show superior accuracy, particularly when dealing with multimodal distributions. This observation highlights the importance of selecting the appropriate sensitivity analysis method based on the nature of the data being analysed. These results provide insights for optimizing stamping processes to reduce production time and costs.

Tight Lower Bound on Differential Entropy for Mixed Gaussian Distributions

In this paper, a tight lower bound for the differential entropy of the Gaussian mixture model is presented. First, the probability model of mixed Gaussian distribution that is created by mixing both discrete and continuous random variables is investigated in order to represent symmetric bimodal Gaussian distribution using the hyperbolic cosine function, on which a tighter upper bound is set. Then, this tight upper bound is used to derive a tight lower bound for the differential entropy of the Gaussian mixture model introduced. The proposed lower bound allows to maintain its tightness over the entire range of the model's parameters and shows more tightness when compared with other bounds that lose their tightness over certain parameter ranges. The presented results are then extended to introduce a more general tight lower bound for asymmetric bimodal Gaussian distribution, in which the two modes have a symmetric mean but differ in terms of their weights.

Relative Entropy Gradient Sampler for Unnormalized Distribution

We propose a relative entropy gradient sampler (REGS) for sampling from unnormalized distributions. REGS is a particle method that seeks a sequence of simple nonlinear transforms iteratively pushing the initial samples from a reference distribution into the samples from an unnormalized target distribution. To determine the nonlinear transforms at each iteration, we consider the Wasserstein gradient flow of relative entropy. This gradient flow determines a path of probability distributions that interpolates the reference distribution and the target distribution. It is characterized by an ordinary differential equation (ODE) system with velocity fields depending on the density ratios of the density of evolving particles and the unnormalized target density. To sample with REGS, we need to estimate the density ratios and simulate the ODE system with particle evolution. We propose a novel nonparametric approach to estimating the logarithmic density ratio using neural networks. Extensive simulation studies on challenging multimodal 1D and 2D mixture distributions and Bayesian logistic regression on real datasets demonstrate that REGS has reasonable performance compared with popular samplers based on Wasserstein gradient flows.

Nonequilibrium statistical mechanics of money/energy exchange models

Many-body dynamical models in which Boltzmann statistics can be derived directly from the underlying dynamical laws without invoking the fundamental postulates of statistical mechanics are scarce. Interestingly, one such model is found in econophysics and in chemistry classrooms: the money game, in which players exchange money randomly in a process that resembles elastic intermolecular collisions in a gas, giving rise to the Boltzmann distribution of money owned by each player. Although this model offers a pedagogical example that demonstrates the origins of Boltzmann statistics, such demonstrations usually rely on computer simulations. In fact, a proof of the exponential steady-state distribution in this model has only become available in recent years. Here, we study this random money/energy exchange model and its extensions using a simple mean-field-type approach that examines the properties of the one-dimensional random walk performed by one of its participants. We give a simple derivation of the Boltzmann steady-state distribution in this model. Breaking the time-reversal symmetry of the game by modifying its rules results in non-Boltzmann steady-state statistics. In particular, introducing ‘unfair’ exchange rules in which a poorer player is more likely to give money to a richer player than to receive money from that richer player, results in an analytically provable Pareto-type power-law distribution of the money in the limit where the number of players is infinite, with a finite fraction of players in the ‘ground state’ (i.e. with zero money). For a finite number of players, however, the game may give rise to a bimodal distribution of money and to bistable dynamics, in which a participant’s wealth jumps between poor and rich states. The latter corresponds to a scenario where the player accumulates nearly all the available money in the game. The time evolution of a player’s wealth in this case can be thought of as a ‘chemical reaction’, where a transition between ‘reactants’ (rich state) and ‘products’ (poor state) involves crossing a large free energy barrier. We thus analyze the trajectories generated from the game using ideas from the theory of transition paths and highlight non-Markovian effects in the barrier crossing dynamics.

The influence patterns of carbon flux in different climatic zones in China --Based on the complex network approach

Abstract Research on ecosystem carbon flux can provide important methodological and strategic support for climate change mitigation. The existing studies focus on the calculation of carbon flux, ignoring the intertwined effects between regions. The quantification and analysis of the interaction patterns of carbon flux is crucial for understanding the global carbon cycle process, forecasting and coping with climate change. In this study, carbon flux network model sequences are established based on complex network theory using carbon flux data spanning from December 1, 2005, to November 30, 2020. The time delay effect is introduced to accurately quantify the influence patterns of carbon flux within climate zones across China. The findings indicate that the probability distribution function of the link weights during the various seasons of each year exhibits a bimodal distribution with distinct positive and negative components. The delay probability distribution function reveals the significant impact of delay effects, which are especially pronounced and mostly significant long-term lag effects in nodes with negative weights. Further, the results of the interactions of carbon flux among climate zones demonstrate that changes in carbon flux in the plateau and southern temperate regions have either positive or negative impacts on other climate zones. Therefore, controlling carbon flux changes in these climatic zones can effectively optimize the distribution of carbon flux. The modeling framework and results presented in this paper provide useful insights for the regulation and distribution optimization of carbon flux in China.

Synergistic inhibition of methane/air explosions by NaHCO3 particles with a bimodal size distribution

To reveal the inhibitory effect of stoichiometric methane/air explosions, NaHCO3 with a bimodal distribution were selected as inhibitors. A 5 L vertical transparent duct was used. All the results revealed that Blend82, whose mass fraction contained 80% OP500–600 and 20% OP200–220 NaHCO3, exhibited the optimal inhibitory effect. For the bimodal distribution of NaHCO3, assessing the inhibitory effect solely on the basis of a single particle size parameter is unreliable. Synergistic effects between particles of different sizes should be considered when the interaction index IS < 1. Multiple size classes of bimodal NaHCO3 were proposed for use in response surface methodology to predict the inhibitory effect of methane/air flames. Furthermore, we employed a detailed chemical kinetic model to quantify the endothermic and chemical effects of NaHCO3 on the laminar burning velocity of methane/air flames and established a good relationship between the explosion parameters and laminar flame properties.

364 Traumatic Dens Fracture Patients Comprise Distinct Subpopulations Distinguished by Differences in Age, Sex, and Injury Mechanism and Severity

INTRODUCTION: Dens fractures are an increasingly common cervical fractures, yet their epidemiology and its implications remain under-examined. METHODS: We retrospectively analyzed all traumatic dens fracture patients managed at our institution over a ten year period with respect to demographic, clinical, and outcomes data. Patient subsets were compared across these parameters. RESULTS: 303 traumatic dens fracture patients were identified, who showed a bimodal age distribution with strong goodness of fit centered at age 22.3 ± 5.7 (R = 0.8781) and at 77.7 ± 13.9 (R = 0.9686). A population pyramid demonstrated a bimodal distribution among male patients, but not among female patients, which was confirmed with a strong goodness of fit for two distinct male patient subpopulations age &lt;35 (R = 0.9791) and age =35 (R = 0.8843), but a weak fit for a second female subpopulation age &lt;35 (24.5 ± 14.2, R = 0.5957). Patients age &lt;35 were more likely to be male (82.4% vs. 46.9%, OR = 5.29 [1.54, 17.57], p = 0.0052). Moreover, patients age &lt;35 were more likely to have MVC as their mechanism of injury (64.7% vs. 14.1%, OR = 11.18 [3.77, 31.77], p &lt; 0.0001), were more likely to have a severe trauma injury severity score (17.6% vs. 2.9%, OR = 7.23 [1.88, 28.88], p = 0.0198). There was no difference with respect to underlying fracture morphology, likelihood of undergoing surgery, having concomitant atlas or subaxial fractures, or Nurick scores at presentation. Patients age &lt;35 were less likely to have fracture nonunion at follow (18.2% vs. 53.7%, OR = 0.19 [0.041, 0.76], p = 0.0288). CONCLUSIONS: The dens fracture patient population comprises two subpopulations, distinguished by differences in age, sex, and injury mechanism and severity, with male dens fracture patients demonstrating a bimodal age distribution. While young patients were more likely to high-energy injury mechanisms leading severe trauma, they were less likely to have fracture nonunion at follow up.

Consumer perception of Cheddar cheese color

The color of Cheddar cheese in the US is influenced by many factors, primarily the amount of annatto added as a colorant. The US FDA is currently reviewing its definition of the term "natural" on food labels, which may result in the use of colorants being restricted in natural cheeses. The objective of this study was to evaluate how consumers perceive Cheddar cheese color to better understand how changes to legislation surrounding colorants in natural Cheddar cheese may affect consumption. We were also interested in determining if a relationship exists between color and other perceived characteristics of Cheddar cheese. Two online surveys on Cheddar cheese color and flavor attributes (n = 1226 and n = 1183, respectively) were conducted, followed by a consumer acceptance test on 6 commercially available Cheddar cheeses (n = 196). Overall, consumers preferred light orange color in Cheddar cheese over dark orange or white Cheddar cheese, but segmentation was observed for Cheddar color preference. Light orange Cheddar and white Cheddar were perceived as approximately equal in terms of "naturalness." White and light orange Cheddars were perceived as more natural than dark orange Cheddars conceptually and in consumer acceptance testing. White Cheddar was considered most natural by 50.3% of n = 1283 survey participants and 43.4% of n = 196 consumer acceptance test participants, while light orange Cheddar was perceived as most natural by 40.6% and 45.9% of these groups respectively. A bimodal distribution was observed in both the online survey and in consumer acceptance testing for "naturalness" of Cheddar cheese color, with a subset of consumers (31.4% of n = 1183 survey participants and 30.6% of n = 196 consumer testing participants) indicating that white Cheddar was the least natural option. Consumers associated orange color in Cheddar cheese with more "sharp" flavor both in an online survey format and consumer acceptance testing.

Effects of ferrite and graphite phases on scratch characteristics of nodular cast iron

In this work, we conduct micro-scratch tests of nodular cast iron with Vickers indenter under constant normal load and investigate the effects of individual phases (i.e., ferrite and graphite phases) on the scratch characteristics of nodular cast iron. Using a bimodal Gaussian model to fit the experimental data of penetration depth, residual depth, elastic recovery rate, and scratch hardness, we calculate the contribution percentages of individual phases to scratch variables. The scratch variables are independent of the scratch speed used in this work, while the penetration depth increases linearly with increasing the normal load. There exists a large difference between the contribution percentages and the volume fractions calculated from SEM images and XRD pattern. Such a large difference suggests that the bimodal Gaussian distribution analysis does not include the effect of the interaction between two phases on the scratch characteristics of dual-phase materials with significantly distinct mechanical properties and geometrical dimensions. A more refined method taking into account the interaction between two phases needs to be developed for the analysis of the scratch characteristics of dual-phase materials.