Partition Values Research Articles

Use of ST/HR hysteresis decreases false positive rate in exercise electrocardiography test of middle-aged asymptomatic women

BackgroundExercise electrocardiography (ECG) is a common diagnostic and prognostic method for the detection of coronary artery disease (CAD). However, its accuracy in asymptomatic women has not been comprehensively investigated and the diagnostic criteria may require refinements. This study evaluated the performance of ECG-derived ST/HR-index, ST/HR hysteresis and ST-segment depression parameters among asymptomatic middle-aged women. Methods108 women (mean age 56 ± 4 years) performed exercise ECG test on treadmill until exhaustion three times within a nine-month period. False-positive rates of maximum ST/HR-index, ST/HR hysteresis, and ST-segment depression values measured from 12 leads at peak exercise and after one-minute recovery were evaluated with recommended diagnostic partition values. Repeatability was assessed with intraclass correlation (ICC) and Bland-Altman plot analysis. ResultsFalse-positive rate was lower for all variables when a two‑lead configuration was used instead of a single‑lead configuration. Using a two‑lead configuration, ST/HR hysteresis (0–1.9 %) and ST-segment depression after one-minute recovery (0–2.8 %) had lower false-positive rates compared to ST/HR index (3.7–20.4 %) and ST-segment depression at peak exercise (9.3–27.8 %). ICC values indicated moderate repeatability for ST/HR hysteresis while ST/HR index, ST-segment at peak exercise, and ST-segment after one-minute recovery had moderate-to-good repeatability. Bland-Altman analysis indicated poor repeatability for all evaluated ECG variables. ConclusionIn asymptomatic middle-aged women, practitioners should prefer the use of ST/HR hysteresis and ST-segment after one-minute recovery over the conventional ST-segment depression at peak exercise or ST/HR index, and evaluate the ECG data from a two‑lead configuration instead of single‑lead.

Heat partition evaluation during dry drilling of thick CFRP laminates with polycrystalline diamond drills

Since various material properties of carbon fiber-reinforced polymer (CFRP) are temperature dependent, dry drilling of CFRP is a delicate process. Thermal damage can be caused by a rise in temperature during drilling due to a large portion of heat being transferred into the material. Heat partition is used to quantify this, which represents the percentage of total heat being dissipated into the constituent objects during a machining operation. Drill margin and contact conditions at the tool-workpiece interface significantly affect the drilling of CFRP material. Drilling experiments were performed to measure thrust force, torque, and temperatures for five different sets of feed rates and rotational speeds. This study proposes a method for calculating heat partition values during CFRP drilling by developing a finite element-based thermal model. The FE model employs a Gaussian distributed ring-type heat flux that is a function of the equivalent contact length at the interface between the drill and the material surface and the geometry of the workpiece which operates as a moving heat source, emulating the progress of the drill through the CFRP laminate. The tool implements heat fluxes that use characteristic time-point-based step functions to represent the temperature on the drill as it advances through the workpiece during machining. The temperature profiles obtained from the FE analysis and the experiments for the workpiece and tool were subsequently matched iteratively to determine the corresponding heat partition value.

The utility of home blood pressure load in predicting average self-measured blood pressure.

Average values for self-measured blood pressure (SMBP) more accurately reflect a patient's risk of cardiovascular disease than do office measurements. Oftentimes, however, patients provide lists of individual home blood pressure (BP) measurements, and average values cannot be computed within the time constraints of a clinic visit. In contrast, the home BP load - defined as the proportion of BP values greater than a partition value (e.g., 130 mmHg) - can be easily calculated. We examined the utility of the BP load in predicting the mean SMBP and confirming elevated SMBP. Four hundred twenty untreated adults at least 30 years of age acquired SMBP data twice in the morning and twice in the evening over 10 days. The 'true' SMBP was defined as the mean of these 40 determinations. Using all 10 days of BP data and a systolic BP threshold of 130 mmHg, the average SMBP associated with a home BP load of 0.50 was 130 mmHg, with a 95% prediction interval of 126-133 mmHg. True systolic SMBP was approximately 6 mmHg lower and higher at home BP loads of 0.25 and 0.75, respectively. There was a 90% probability that the true systolic SMBP was greater than 130 mmHg if the systolic home BP load was at least 0.60. Corresponding values for 3 days and 1 day of SMBP were at least 0.68 and at least 0.84, respectively. Our analysis demonstrates that the home BP load can be used to estimate the average BP acquired on home monitoring and confirm elevated SMBP.

Temperature Field Characteristics of Limited Slip Clutch under Various Condition Parameters

The temperature field of limited slip clutch (LSC) seriously interferes with torque transmission. In this paper, the attribute of dynamic partition of slip heat flux is considered. A calculation model of temperature field is also established by combining the proposed new method of fluid-solid equivalent convective heat transfer. The simulation and experiment of different relative speed, lubricant flow, and temperature are carried out. Furthermore, the comprehensive evaluation index of average temperature growth ratio and maximum radial temperature difference is proposed. The results show that the deviations of temperature rising rate and average temperature are not more than 0.2 °C/s and 6 °C, respectively. Heat flux partition value of separator plate increases approximately proportionally with relative speed. Changing relative speed from 40 r/min to 80 r/min, average temperature growth rate and maximum radial temperature difference of separator plate increase by 0.35 °C/s and 2.08 °C, respectively. On the contrary, increasing lubricant flow or reducing lubricant temperature weakens actual heat flux input of clutch. From 3 L/min to 10.5 L/min about lubricant flow, the average temperature growth rate and maximum radial temperature difference caused by higher relative speed are reduced by 0.32 and 2.71 °C, respectively. However, when lubricant temperature is adjusted from 65 °C to 30 °C, average temperature growth rate is reduced by 0.51 and the variation of maximum radial temperature difference does not exceed 0.32 °C. The research can accurately simulate actual energy flow at friction pair interface and assist in exploring the influence of condition parameters on temperature field.

Assessing the suitability of leachability-based screening levels for per- and polyfluoroalkyl substances (PFAS) risk assessment

In recent years, soil screening levels have been adopted by regulatory agencies for certain per- and polyfluoroalkyl substances (PFAS) to assess the risk of groundwater contamination through leaching. These soil screening levels, determined using an established equilibrium-based partitioning equation, have high variability among regulatory groups largely attributed to the diverse reported partitioning coefficients in the literature. This variability between reported partitioning coefficients, and subsequently soil screening levels, is due to the complex leaching behavior of PFAS not being predicted well by the standard equilibrium-based model. This has led one regulatory group to require batch leaching to assess risk rather than setting default soil screening levels based on partitioning equations. In this work, we conducted leaching experiments on five field-sampled soils impacted by aqueous film-forming foams (AFFF), following Leaching Environmental Assessment Framework (LEAF) Method 1316 and compared the results to expected leaching utilizing an equilibrium-based partitioning equation commonly employed by regulatory agencies to establish soil screening levels. Our analysis found among the six PFAS detected in the soils, which have regulatory leaching thresholds established, the partitioning values assumed by the U.S. EPA exhibited the highest accuracy in predicting leachate concentrations. These partitioning values predicted actual leaching within a ± 20 % margin of error for approximately 50 % of sample points, highlighting limitations in relying solely on equilibrium-based partitioning values as predictors of leaching behavior. This discrepancy between predicted and actual leaching has implications for site managers and regulatory entities overseeing PFAS-contaminated sites, suggesting that soil screening level determinations for PFAS might need to be revised to account for the unique transport characteristics of PFAS.

Reconsidering the Price equation: Benchmarking the analytical power of additive partitioning in ecology

The Price approach allows the partitioning of composite variables into a set of additive components and has become an important tool in evolutionary and ecological research. However, because such components are not mutually independent and might be constrained by the inherent data structure, comparing and interpreting Price partitions among different datasets is not straightforward and has contributed to controversy in ecology.Here we discuss and develop null model approaches that might be used as statistical standards to normalise partition values and reduce collinearity between partitions. We use a simulation approach to estimate Price partitions of artificial data and their randomisations. Using structural equation modelling we then reveal the degree of collinearity between raw and standardised partitions.We first demonstrate that the degree of collinearity between partitions strongly depends on the data structure and then provide a general framework for null model selection. Null models that require limited additional information on the possible distribution of species richness and abundance perform best. These null models consistently reduce, but do not fully eliminate, collinearity between partitions. They assign separate type I and II error levels to each partition that differed among partitions.We argue in favour of null models that strike a balance between information need (simplicity) and complexity of additional information, but we discourage the use of simple permutation approaches that have been successful for analysing other biodiversity measures such as species richness. We highlight that the interpretation of additive partitions of complex ecological data will benefit from analyses of the dependence among partitions.

A Tale of Two Peas in a Pod: The Kepler-323 and Kepler-104 Systems

In order to understand the relationship between planet multiplicity, mass, and composition, we present newly measured masses of five planets in two planetary systems: Kepler-323 and Kepler-104. We used the HIRES instrument at the W.M. Keck Observatory to collect 79 new radial velocity (RV) measurements for Kepler-323, which we combined with 48 literature RVs from TNG/HARPS-N. We also conducted a reanalysis of the Kepler-104 system, using 44 previously published RV measurements. Kepler-323 b and c have masses of 2.0−1.1+1.2 M ⊕ and 6.5±1.6 M ⊕, respectively, whereas the three Kepler-104 planets are more massive (10.0±2.8 M ⊕, 7.1−3.5+3.8 M ⊕, and 5.5−3.5+4.6 M ⊕ for planets b, c, and d, respectively). The Kepler-104 planets have densities consistent with rocky cores overlaid with gaseous envelopes ( 4.1−1.1+1.2 g cc−1, 2.9−1.5+1.7 g cc−1, and 1.6−1.1+1.5 g cc−1 respectively), whereas the Kepler-323 planets are consistent with having rocky compositions ( 4.5−2.4+2.8 g cc−1 and 9.9−2.5+2.7 g cc−1). The Kepler-104 system has among the lowest values for gap complexity ( C = 0.004) and mass partitioning ( Q = 0.03); whereas, the Kepler-323 planets have a mass partitioning similar to that of the Inner Solar System ( Q = 0.28 and Q = 0.24, respectively). For both exoplanet systems, the uncertainty in the mass partitioning is affected equally by (1) individual mass errors of the planets and (2) the possible existence of undetected low-mass planets, meaning that both improved mass characterization and improved sensitivity to low-mass planets in these systems would better elucidate the mass distribution among the planets.

Partition of humic acids using alkaline aqueous two‐phase systems constituted of alcohol and hydroxides

AbstractBACKGROUNDHumic acids (HAs) are macromolecules classified within the group of humic substances that are mainly related to the agricultural and environmental sectors, but they have attracted interest from the medicine, pharmaceutical and cosmetic industries. However, these latter sectors depend on developing extraction and purification technologies for adequate use. Thus, this paper aims to study the partitioning and recovery of HA using alkaline two‐phase aqueous systems (ATPSs) based on alkali metal‐based hydroxides and alcohols. Initially, the influence of alcohols (methanol, ethanol, 1‐propanol, and 2‐propanol) and hydroxides [sodium (NaOH), potassium (KOH) and lithium (LiOH)] in the phase diagrams construction was addressed.RESULTSThe phase formation is correlated to an increase in the hydrophobicity of alcohols and hydroxides, which allows for the enlargement of the biphasic region. In the proposed systems, HA is always partitioned to the hydroxide‐rich phase. Increasing the hydrophobicity of the alcohol favors the migration of HA to the opposite phase, while increasing the hydrophilicity of the hydroxides leads to better partition and recovery values. It was observed that increasing TLL favors the recovery of HA. Furthermore, there was a decrease in alcohol concentration in the hydroxide‐rich phase with an increase in the alkyl chain and TLL, improving the recovery. Finally, the best reached‐recovery value was 98.18 ± 0.41% (KHA = 0.038 ± 0.02) for ATPS formed by 1‐propanol + NaOH with TLL ≈ 55 at 298 K.CONCLUSIONSAlkaline systems can be a novel route for recovering humic substances from the environment. © 2024 Society of Chemical Industry (SCI).

Membrane Partitioning of TEMPO Discriminates Human Lung Cancer from Neighboring Normal Cells.

The plasma membranes of normal and cancer cells of the lung, breast, and colon tissues show considerably different lipid compositions that greatly influence their physicochemical properties. Partitioning of the spin probe 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) into the membranes of human lung normal and carcinoma cells was assessed by EPR spectroscopy to estimate the impact of the lipid compositions. The goal was to reveal potential strategies for cancer therapy attributable to the membrane properties. The study was conducted at pH values of 7.3 and 6.2, relevant to the microenvironments of normal and cancer cells, respectively. The TEMPO partitioning was examined in the temperature interval of 283-317K to reveal the efficacy of local hyperthermia used in chemotherapy. Results indicate that the TEMPO partitioning coefficient for the membranes of human lung carcinoma cells is significantly higher compared with that of neighboring normal cells. Increased partition coefficients were observed at relatively higher temperatures in both normal and cancer cells. However, compared to the normal cells, the cancer cells demonstrated higher partition coefficients in the studied temperature range. The data obtained with C12SL (spin-labeled analog of lauric acid) indicate that increased membrane dynamics of the cancer cells is a possible mechanism for enhanced partitioning of TEMPO. Free energy values for partitioning estimated for pH values of 6.2 and 7.3 show that TEMPO partitioning requires 30% less energy in the cancer cells at pH 7.3. TEMPO and its derivatives have previously been considered as theranostic agents in cancer research. Data suggest that TEMPO derivatives could be used to test if complementary alkalization therapy is effective for cancer patients receiving standard chemotherapy with local hyperthermia.

Minor effect of wind exposure and littoral slope on macrophyte characteristics in non-impacted lowland lakes of Poland.

Aquatic vegetation is a reliable indicator of the ecological condition of surface waters. Abundance, composition and spatial structure of aquatic communities are shaped by an array of factors, which include both natural abiotic features of an ecosystem and external influences. We investigated whether the physical features, i.e., wind exposure and slope of the lake basin, have a significant impact on the taxonomic composition and spatial structure of macrophyte communities from non-impacted, highly alkaline, lowland lakes of the European plains (Poland). We further examined whether these features can affect the classification of the ecological status of lakes assessed in accordance with the Water Framework Directive requirements. Morphological, botanical and physicochemical data from 260 transects in 16 non-disturbed lakes of Polish lowlands surveyed in the years 2011-2016 were analysed. For each transect, littoral slope and wind exposure were calculated. Additionally, the total phosphorus concentration was used as a proxy of water trophy. The relationships between environmental variables and macrophyte indices as well as the syntaxonomic composition of aquatic and rush vegetation (dependent variables) were analysed using multidimensional ordination techniques (redundancy analysis, variation partitioning and indicator values), correlation and regression analysis. Among the three analysed environmental factors (littoral slope, wind exposure and water trophy), in almost all cases the latter explained the highest variance in the macrophyte community, while the contribution of the first two was at most moderate, weak or usually statistically insignificant. However, lakes with steeper slopes were more frequently inhabited by stoneworts and had better ecological status than those with a gentle littoral shape. This may be attributed to the links between lake morphometry and rate of eutrophication, with deep lakes supporting more effective dilution of substances. Furthermore, lower light requirements of charophytes than of higher plants and the capacity to growth in unstable sediments facilitate charophyte establishment in deeper and steeper parts of the littoral over higher plants. Our findings suggest that in lowland lakes with relatively small areas, moderate depths and low wind exposure typical of European plains, slopes and weaving do not hamper vegetation development and do not negatively affect the macrophyte assessment of ecological status. In such ecosystems, eutrophication seems to be a more important factor determining aquatic vegetation than physical features.

Toward Data Integrity Attacks Against Distributed Dynamic State Estimation in Smart Grid

With the continuous expansion of the power grid nodes scale, traditional centralized state estimation method shows certain limitations in estimation efficiency and accuracy. Recently, some power grids adopt a distributed state estimation method, in which each partition independently estimates the partial state information by partitioning the entire power system. However, the deviation of the state estimation in certain partition will result in the deviation of the estimation results in the entire power grid system. In this paper, we propose the attack strategy against the distributed state estimation in smart grids from two perspectives, i.e. the attack against local physical measurement value of the power system partition and the attack against the measurement value of coordination center. Moreover, the theoretical analysis of the state estimation deviation caused by the proposed data integrity attack and the propagation processes of proposed attack vectors in measurement calculations are formalized. The effectiveness of the proposed attack strategy is verified in the IEEE-30 bus and IEEE-118 bus systems. Simulation results show that attacking against a certain partition of a distributed system can indirectly affect the state estimation results of other partitions and attacking against the measurement value of coordination center can directly threaten the state estimation results of the entire power grid. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This paper proposes two attack strategies against the distributed state estimation of power grid from two perspectives, i.e. the attack against local physical measurement value of the power system partition and the attack against the measurement value of coordination center. Most of the previous works fail to formalize the state estimation deviation of both partial and entire state estimation results of power grid after the attacker launches the attack against the distributed state estimation. We formalize the state estimation deviation caused by the proposed data integrity attack and the propagation processes of proposed attack vectors in measurement calculations. The effectiveness of the proposed attack strategy against the state estimation of power grid is verified in the IEEE-30 bus and IEEE-118 bus systems. Simulation results show that attacking against a certain partition of power grid can indirectly cause the deviation in the state estimation results of entire power grid and attacking against the measurement value of the coordination center can directly threaten the state estimation results of the entire power grid. In conclusion, the proposed attack strategies are helpful for the research community to design detection strategies in a targeted manner and can be conveniently applied to the real-world security management system of smart grid.

Elderly patients with stage II gastric cancer do not benefit from adjuvant chemotherapy

BackgroundWith the aging of the population, the burden of elderly gastric cancer (EGC) increases worldwide. However, there is no consensus on the definition of EGC and the efficacy of adjuvant chemotherapy in patients with stage II EGC. Here, we investigated the effectiveness of adjuvant chemotherapy in defined EGC patients.MethodsWe enrolled 5762 gastric cancer patients of three independent cohorts from the Sixth Affiliated Hospital of Sun Yat-sen University (local), the Surveillance, Epidemiology, and End Results (SEER), and the Asian Cancer Research Group (ACRG). The optimal age cutoff for EGC was determined using the K-adaptive partitioning algorithm. The defined EGC group and the efficacy of adjuvant chemotherapy for them were confirmed by Cox regression and Kaplan–Meier survival analyses. Furthermore, gene set variation analyses (GSVA) were performed to reveal pathway enrichment between groups.ResultsThe optimal age partition value for EGC patients was 75. In the local, SEER, and ACRG cohorts, the EGC group exhibited significantly worse overall survival and cancer-specific survival than the non-EGC group (P < 0.05) and was an independent risk factor. Stratified analyses based on chemotherapy showed that EGC patients derived little benefit from adjuvant chemotherapy. Furthermore, GSVA analysis revealed the activation of DNA repair-related pathways and downregulation of the p53 pathway, which may partially contribute to the observed findings.ConclusionIn this retrospective, international multi-center study, 75 years old was identified as the optimal age cutoff for EGC definition, and adjuvant chemotherapy proved to be unbeneficial for stage II EGC patients.

Thermodynamic modelling of the partitioning of lysozyme in aqueous two-phase systems composed of polyethylene glycol and salt at different temperatures

Knowledge about the interactions during the protein transfer is necessary to optimize the application of aqueous two-phase systems (ATPS) in purification processes. Theoretical knowledge combined with modelling and simulation can help to select the systems with the best partition values. Therefore, this study aimed to determine new interaction parameters through the contribution groups of lysozyme, using UNIFAC (Universal Functional Activity Coefficient) modelling. First, the partition of lysozyme was carried out, and the polymer molar mass (4000 or 6000), and the effects of the type of salt (Na2SO4 or Na3C6H5O7), the overall composition of the system (3 mooring lines), and temperature T = (293.15, 298.15, 303.15 and 308.15) K were evaluated. The results showed that lysozyme had a preference for the bottom phase of the ATPS system, the increase in the overall composition led to a tendency of increasing the partition coefficient (Kp), and the systems made up of higher molar mass polymers exhibited a bottom Kp value. The results of the thermodynamic parameters showed that the transfer of lysozyme in the phases was governed by entropy contribution. New interaction parameters of the contribution groups of lysozyme in the system phases were estimated. The UNIFAC model showed low deviation values. Therefore, the present results allow estimating new partitioning data for proteins presenting the same contribution groups, which can reduce the number of experiments and optimize the partitioning process.

Forest floor and Na azide effect on elements in leachate from contrasting New Hampshire and Virginia forest soils

AbstractAs northeastern forests experience increased temperatures and fluctuations in precipitation patterns, montane soils will lose forest floor (Oi, Oe, Oa horizons) formation and their associated ecosystem services. Here, we conducted comparative laboratory soil column experiments to examine the effects of forest floor on sourcing and weathering of macroelements (Al, Si), macronutrients (Ca, Mg, P), and micronutrients (Cu and Zn) from two contrasting soils: a supraglacial‐till Inceptisol (Mt. Moosilauke, NH) and colluvium Ultisol (Lesesne State Forest, VA). Forest floor addition caused a significant increase in the leaching of Ca, Mg, and Mn in the two soils. The forest floor only control leachate indicates the two mineral soils were net accumulators of Al, Si, P, Cu, and Zn from the forest floor. Using partition coefficient, Kd, values, leachate Ca and Mg could be sourced directly from the forest floor traversing the soil column. We aimed to assess the biotic influence on element release from soil using a Na azide treatment to suppress microbial activities. Under Na azide treatments, Al, Ca, Mg, Mn, and Cu leachate decreased significantly for both soils, but Na azide also did not affect or increased leachate Si, P, Cu, and Zn for the Lesesne soil. We attribute the effects from Na azide to changes in pH, dissolved organic carbon, and oxidation‐reduction potential as opposed to suppression of microbes. Thus, our results suggest that the loss of the forest floor will reduce the storage of nutrients in the mineral soil, even across varying parent materials.

Underwater polarization image restoration based on a partition method

The quality of underwater polarization imaging is mainly affected by the polarization properties of the target and impurity particles. Traditional methods often assume uniform polarization characteristics of the target, which make it difficult to address the restoration issues of complex targets. In response, a partition-based method for recovering underwater polarization images is proposed. The method involves pre-processing the image using the Gaussian curvature filtering algorithm, partitioning the image based on polarization information. In addition, a joint image evaluation method is used to achieve restoration of complex polarized characteristic targets. The method estimates the value of the reflected light polarization of one partition to estimate the value of the next partition and links the polarization values of each partition. Our approach achieves clear restoration results for multiple targets or complex structural objects underwater. Achieving significant improvement in image quality in multi-target underwater scenes, our method is highly effective for complex underwater environments. Experimental results show that our method, when compared with three other newer methods on multiple images of different targets and under varying scattering conditions, achieves an average increase of 617% in the standard deviation image evaluation index and a 61% optimization in the natural image quality evaluator index. Furthermore, our method is robust for different degrees of water turbidity.

Adaptive differential evolution algorithm with a pheromone-based learning strategy for global continuous optimization

Abstract Differential evolution algorithm (DE) is a well-known population-based method for solving continuous optimization problems. It has a simple structure and is easy to adapt to a wide range of applications. However, with suitable population sizes, its performance depends on the two main control parameters: scaling factor (F ) and crossover rate (CR). The classical DE method can achieve high performance by a time-consuming tunning process or a sophisticated adaptive control implementation. We propose in this paper an adaptive differential evolution algorithm with a pheromone-based learning strategy (ADE-PS) inspired by ant colony optimization (ACO). The ADE-PS embeds a pheromone-based mechanism that manages the probabilities associated with the partition values of F and CR. It also introduces a resetting strategy to reset the pheromone at a specific time to unlearn and relearn the progressing search. The preliminary experiments find a suitable number of subintervals (ns) for partitioning the control parameter ranges and the reset period (rs) for resetting the pheromone. Then the comparison experiments evaluate ADE-PS using the suitable ns and rs against some adaptive DE methods in the literature. The results show that ADE-PS is more reliable and outperforms several well-known methods in the literature.

Automatic Inhomogeneous Background Correction for Spatial Target Detection Image Based on Partition Processing

High-resolution imaging with wide field of view (FoV) ground-based telescopes is often affected by skylight background and noise due to the detector, resulting in an inhomogeneous background. In this paper, we propose an improved method for spatial image non-uniformity correction based on partition processing. First, an evaluation metric is introduced to evaluate the partition size and automatically iterate a suitable partition value for different scenarios based on the different operating conditions of the telescope. Then, we iteratively calculate the mean and variance in each partitioned region to extract the background of each partitioned region. Finally, after applying bilinear interpolation to the background extracted from each region, the inhomogeneous background is obtained and removed from the original image. The experiments on the simulated and real images show that the proposed method can effectively remove the inhomogeneous background of spatial images and meet the requirements of the real-time processing of high-resolution images under long exposure conditions.

Predicting Concentration- and Ionic-Strength-Dependent Air-Water Interfacial Partitioning Parameters of PFASs Using Quantitative Structure-Property Relationships (QSPRs).

Air-water interfacial retention of poly- and perfluoroalkyl substances (PFASs) is increasingly recognized as an important environmental process. Herein, column transport experiments were used to measure air-water interfacial partitioning values for several perfluoroalkyl ethers and for PFASs derived from aqueous film-forming foam, while batch experiments were used to determine equilibrium Kia data for compounds exhibiting evidence of rate-limited partitioning. Experimental results suggest a Freundlich isotherm best describes PFAS air-water partitioning at environmentally relevant concentrations (101-106 ng/L). A multiparameter regression analysis for Kia prediction was performed for the 15 PFASs for which equilibrium Kia values were determined, assessing 246 possible combinations of 8 physicochemical and system properties. Quantitative structure-property relationships (QSPRs) based on three to four parameters provided predictions of high accuracy without model overparameterization. Two QSPRs (R2 values of 0.92 and 0.83) were developed using an assumed average Freundlich n value of 0.65 and validated across a range of relevant concentrations for perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and hexafluoropropylene oxide-dimer acid (i.e., GenX). A mass action model was further modified to account for the changing ionic strength on PFAS air-water interfacial sorption. The final result was two distinct QSPRs for estimating PFAS air-water interfacial partitioning across a range of aqueous concentrations and ionic strengths.

In Silico Prediction of Stratum Corneum Partition Coefficients via COSMOmic and Molecular Dynamics Simulations.

Stratum corneum (SC) is the main barrier of human skin where the inter-corneocytes lipids provide the main pathway for transdermal permeation of functional actives of skin care and health. Molecular dynamics (MD) has been increasingly used to simulate the SC lipid bilayer structure so that the barrier property and its affecting factors can be elucidated. Among reported MD simulation studies, solute partition in the SC lipids, an important parameter affecting SC permeability, has received limited attention. In this work, we combine MD simulation with COSMOmic to predict the partition coefficients of dermatologically relevant solutes in SC lipid bilayer. Firstly, we run MD simulations to obtain equilibrated SC lipid bilayers with different lipid types, compositions, and structures. Then, the simulated SC lipid bilayer structures are fed to COSMOmic to calculate the partition coefficients of the solutes. The results show that lipid types and bilayer geometries play a minor role in the predicted partition coefficients. For the more lipophilic solutes, the predicted results of solute partition in SC lipid bilayers agree well with reported experimental values of solute partition in extracted SC lipids. For the more hydrophilic molecules, there is a systematical underprediction. Nevertheless, the MD/COSMOmic approach correctly reproduces the phenomenological correlation between the SC lipid/water partition coefficients and the octanol/water partition coefficients. Overall, the results show that the MD/COSMOmic approach is a fast and valid method for predicting solute partitioning into SC lipids and hence supporting the assessment of percutaneous absorption of skin care ingredients, dermatological drugs as well as environmental pollutants.

On certain McKay numbers of symmetric groups

For primes $$\ell $$ and nonnegative integers a, we study the partition functions $$\begin{aligned} p_\ell (a;n):= \#\{\lambda \vdash n : \textrm{ord}_\ell (H(\lambda ))=a\}, \end{aligned}$$ where $$H(\lambda )$$ denotes the product of hook lengths of a partition $$\lambda $$ . These partition values arise as the McKay numbers $$m_\ell (\textrm{ord}_\ell (n!) - a; S_n)$$ in the representation theory of the symmetric group. We determine the generating functions for $$p_\ell (a;n)$$ in terms of $$p_\ell (0;n)$$ and specializations of specific D’Arcais polynomials. For $$\ell = 2$$ and 3, we give an exact formula for the $$p_\ell (a;n)$$ and prove that these values are zero for almost all n. For larger primes $$\ell $$ , the $$p_\ell (a;n)$$ are positive for sufficiently large n. Despite this positivity, we prove that $$p_\ell (a;n)$$ is almost always divisible by m for any integer m. Furthermore, with these results we prove several Ramanujan-type congruences. These include the congruences $$\begin{aligned}p_\ell (a;\ell ^k n - \delta (a,\ell )) \equiv 0 \,\,(\textrm{mod}\,\,{\ell ^{k+1}}), \end{aligned}$$ for $$0<a< \ell $$ , where $$\ell = 5, 7, 11$$ and $$\delta (a,\ell ) := (\ell ^2 - 1)/24 + a\ell $$ , which answer a question of Ono.