Applicable Method Research Articles

Large-ensemble Monte Carlo: a researcher’s guide to better climate trend uncertainties

Abstract Internal climate variability (ICV) often violates the assumptions of statistical methods, and the climate research community does not have an established approach for addressing resulting biases. Here we argue for a technique we call climate model Large-Ensemble Monte-Carlo (LENS-MC) to inform the selection of statistical methods for real-world application. Until now, scientists have often made best efforts to select methods based on assumptions about the mathematical properties of ICV. LENS-MC relaxes these assumptions and justifies method selection, potentially for a wide range of statistical analyses. We demonstrate LENS-MC using a case study of statistical errors in 20 year trends in global temperature and top-of-atmosphere flux series, comparing results with standard ordinary least squares (OLS). OLS commonly underestimates trend uncertainties, resulting in a higher likelihood of falsely reporting statistically significant trends or changes in trends, for example reporting p < 0.05 in 20 year temperature trends when the statistics are actually equivalent to p < 0.56. LENS-MC tests result in the selection of methods that almost eliminate the low bias in OLS trend standard errors. Using the suggested methods, researchers are less likely to mistakenly report significant trends, and LENS-MC could be widely applied to statistical climate analysis for which model output is available, provided that model ICV displays similar statistical structure, such as in autocorrelation, to observed ICV.

Additive inclusion in plastic life cycle assessments, part II: Review of additive inventory data trends and availability

AbstractPlastic additives are as essential as polymers to the production and performance of plastic materials. Additive content can vary in composition and functionality depending on the product, producer, application, and production method. Such variation may be a barrier to achieving high‐quality recycling and planning for plastic circular economy futures. Yet, as found in Part I, although there is increasing awareness of the importance of additives in plastics, they are often poorly disclosed or only briefly discussed in life cycle assessments (LCAs). In part II, we focus on the inclusion of additives in plastic processes in the database most used in plastic LCAs to date (Ecoinvent) and find that additives have historically been omitted from plastic granulate data and in production processes in the evaluated database. Thus, many practitioners will need to separately include additives in their models of plastic life cycles. To support practitioners in this endeavor, we then assess the availability of the 13,587 additives identified in the recent UN Chemicals in Plastics Report across the three major LCI databases (CarbonMinds, Ecoinvent, and LCA for Experts [GaBi]). We find that databases currently cover only 1,209 of these additives. Moreover, we assert that transparency regarding additive inclusion in plastics datasets, availability of additive datasets, and additive data completeness are major barriers to additive inclusion in plastic LCAs. Thus, we recommend focusing on the development of additive datasets, and we provide a tool for the identification of additive dataset availability and data gaps to improve the quality of plastic LCAs.

Seed- and Foliar-Applied Iron Chelate Improves Performance, Physiological, and Biochemical Aspects of Black Cumin (Nigella sative) under Semi-Arid Conditions

The cultivation of medicinal plants plays a crucial role in promoting human health benefits. However, the production of these plants can be affected by drought conditions. This research aimed to investigate the impact of differing water status (non-drought and drought during the flowering to harvest stage) and various iron treatments on the performance of black cumin. The iron treatments included no iron as the control (nFe), no iron with seed hydro-priming (nFe + P), seed iron priming (pFe), seed iron priming with iron foliar spraying (pFe + sFe), and double iron foliar spraying (sFe + sFe). The purpose of these treatments was to assess the effect of iron application methods on plant response under different water conditions. The findings revealed that drought significantly reduced the levels of Chla (15%) and RWC (5.9%), plant height (7%), follicle number (16.7%), seed number (4.6%), 1000-seed weight (3.2%), and seed yield (30.1%). Additionally, drought increased the proline content (90.9%), electrolyte leakage (9.2%), and MDA levels (23.9%). Interestingly, applying iron amendments reduced electrolyte leakage and increased seed yield under both water conditions. The drought-induced increase in proline content was more pronounced in the nFe treatment than in the other treatments. The amount of MDA in the nFe and nFe + P treatments was significantly higher under drought conditions compared to non-drought conditions. In conclusion, the addition of iron amendments helps black cumin plants recover from the effects of drought and reduces damage to seed growth. This means that using both seed iron priming and iron foliar spraying can significantly improve yields. Alternatively, focusing on either seed iron priming or double iron foliar spraying can also boost black cumin production compared to not using iron amendments.

Pore pressure prediction based on rock physics theory and its application in seismic inversion

Formation overpressure seriously affects drilling and downhole operation. Accurate prediction on the formation pore pressure can not only reduce the probability of drilling accidents, but also quantitatively evaluate the original formation pressure of underground pore space, which provides an important reference for site selection of carbon sink projects using underground space resources such as CO2 geological storage. It is therefore necessary to set up a widely applicable method that is based on rock physics theory and conforms to the characteristics of rock mechanics and fluid mechanic. This method is suitable for both logging prediction and seismic inversion of pore pressure. The traditional method of predicting pore pressure based on P-wave velocity has multiple solutions, and the prediction based on S-wave velocity which is not sensitive to fluid has new significance. Based on the Hertz-Mindlin petrophysical model that considering pressure variation and the Gassmann fluid substitution equation that addresses the change in fluid saturation, this paper firstly derived rock physical formulas for predicting pore pressure in logging, and then derived the intrinsic power function relationship between the effective pressure (Pe) and S-wave velocity (Vs) as well as S-wave impedance (Is). Based on this, a set of geophysical methods integrating S-wave velocity prediction, pore pressure prediction in well and seismic inversion is finally established. The efficacy of this method has been well validated, with an average error of 2.35% in S-wave velocities prediction, 4.5% in single-well pore pressure prediction. The results of seismic inversion of pore pressure are consistent with the phenomenon of overpressure development in actual working area. This method can be further extended to other areas, providing invaluable reference for underground operation such as oil and gas exploration and CO2 geological storage.

Development of a holistic framework for the description and characterization of company-individual Manufacturing Change Management processes

AbstractIn today’s manufacturing industry, companies operate in a complex and rapidly changing environment, resulting in an increasing number and variety of Manufacturing Changes (MCs). To ensure long-term competitiveness, companies must respond quickly, flexibly, and effectively to various types of MCs. While many companies have established processes to manage MCs, these processes often lack flexibility and a comprehensive methodological and digital support. Existing approaches to support these processes are often generic and difficult to transfer to a company’s unique Manufacturing Change Management (MCM) process. For this purpose, a framework and an associated application method have been developed in which MCM processes are abstracted and mathematically modeled using descriptive and characterizing attributes. To achieve a comprehensive view of the processes, the holistic framework intends to model people’s activities involved in the process, process steps, and the occurrence of information inside the process. The framework was developed through a three-phase approach, with attributes derived from the literature, case studies, and expert interviews. The framework and the associated application method were tested in a first industrial use case. In conclusion, the framework developed in this contribution supports practitioners and researchers to consistently describe and to flexibly adapt generally valid theoretical and practical approaches to company-individual MCM processes.

Comparing mini-disk infiltrometer, BEST method and soil core estimates of hydraulic conductivity of a sandy-loam soil

Saturated, Ks, and near-saturated, K, soil hydraulic conductivity control many hydrological processes but they are difficult to measure. Comparing methods to determine Ks and K is a means to establish how and why these soil hydrodynamic properties vary with the applied method. A comparison was established between the Ks and K values of a sandy-loam soil obtained, in the field, with the BEST (Beerkan Estimation of Soil Transfer parameters) method of soil hydraulic characterization and an unconfined MDI (mini-disk infiltrometer) experiment and, in the laboratory, with a confined MDI experiment and the CHP (constant-head permeameter) method. Using for the BEST calculations the soil porosity instead of the saturated soil water content yielded 1.4–1.1 times higher estimates of Ks and K, depending on the pressure head, and differences decreased in more unsaturated soil conditions. The confined MDI experiment yielded 22 % - 77 % higher K values than the unconfined MDI experiment, depending on the established pressure head, h0, and differences were not significant for h0 = −1 cm. In the close to saturation region, the soil hydraulic conductivity function predicted with BEST did not generally agree well with the Ks and K values obtained in the laboratory by a direct application of the Darcy’s law. In particular, BEST yielded a 5.6 times smaller Ks value than the CHP method and up to an 8.1 times higher K value than the MDI. Overall, i) the two application methods of the MDI yielded relatively similar results, especially close to saturation, and ii) there was not a satisfactory agreement between the field (BEST) and the laboratory (MDI plus CHP) determination of soil hydraulic conductivity close to saturation, unless a comparison was made with the same soil water content. The detected differences were probably attributable to soil spatial variability, overestimation of Ks in the laboratory due to preferential flow phenomena, underestimation of Ks in the field due to air entrapment in the soil and infiltration surface disturbance, inability of BEST to describe the actual soil hydraulic conductivity function at the sampled field site. Testing BEST predictions of Ks and K in other soils appears advisable and combining the MDI and CHP methods appears a rather simple means to make these checks. These additional investigations could improve interpretation of the differences between methods, which is an important step for properly selecting a method yielding Ks and K data appropriate for an intended use.

Exploring the effectiveness of doxycycline in restorative dentistry: a systematic review of in vitro studies.

This systematic review evaluated the efficacy of doxycycline in MMP inhibition, its antibacterial action, and other properties relevant to dental materials testing. The study protocol was registered at the Open Science Framework ( https://doi.org/10.17605/OSF.IO/ZVK2T ). Reporting was based on PRISMA statement. The search was carried out in the databases: PubMed, Scopus, Web of Science, Embase, Lilacs, and Google Scholar. Articles were restricted to Portuguese, English, and Spanish, with no date limit. In vitro studies were selected based on the following outcomes: DOX antibacterial and anti-metalloproteinase activity and its influence in physico-chemical properties. Two researchers independently selected the articles and collected the data. Of 1507 documents, 82 were fully evaluated and 21 were included. Different forms of doxycycline incorporation were found, both as free form and incorporated into carrier agents. The drug was tested as primers, incorporated in adhesive or glass ionomer cement. No studies were found that evaluated its incorporation in resin composite or resin cement. The results confirmed the therapeutic properties of the medication, with more significant results when incorporated in an adhesive. However, although promising, the use of this substance requires standardization in application methods and adopted concentrations, allowing for more direct comparisons between studies. Furthermore, long-term studies are interesting to conduct, ensuring biocompatibility and complete understanding of long-term effects on dental materials.

Thermodynamic Consideration of the Direct Removal of Oxygen from Titanium by Utilizing Metallothermic Reduction of Rare Earth Metal Halides

As the demand for titanium (Ti) continues to grow, so too does the use of Ti scrap, underscoring the need for innovative techniques for the efficient removal of oxygen (O) impurities from Ti scrap. Despite the immense challenge of directly removing oxygen from Ti–O solid solutions and the current lack of industrially applicable deoxidation methods, the current work explores a groundbreaking approach to address this issue. The thermodynamic analysis of a new technique for eliminating oxygen dissolved in solid Ti was conducted, leveraging the deoxidation properties of rare earth metals (REMs) such as Sc, Y, and La. This cutting-edge method relies on the in-situ production of REMs through the metallothermic reduction of REM halides. It was shown that Sc or Y metal can be synthesized via the reduction of ScCl3 by Mg or YCl3 by Li or Na, respectively. Ti with oxygen concentrations below 100 mass ppm can be obtained by leveraging the deoxidation properties of the Sc and Y metals produced in situ during the metallothermic reduction process, which contribute to deoxidation through their subsequent oxychloride-forming reactions. Employing REM halides in tandem with Li, Na, and Mg enables the efficient removal of oxygen impurities from Ti, even though these reactive metals have only weak deoxidation properties for Ti on their own. Remarkably, the proposed technique achieves oxygen concentrations significantly lower than those obtained using Ca metal as a deoxidant. In the future, this pioneering deoxidation method could be used to reduce CO2 emissions and energy consumption during Ti production while promoting resource circulation as a key technology for Ti recycling.

Application framework and model of Jingjin therapy in rehabilitation medicine

The Jingjin therapy and rehabilitation medicine share commonalities and complement each other. The application of Jingjin therapy from a rehabilitation perspective can broaden the development path of traditional Chinese medicine (TCM) rehabilitation. This paper, based on relevant literature and research findings, elaborates on the connection between Jingjin syndrome differentiation acupuncture and rehabilitation assessment and treatment. It discusses the application framework of Jingjin's preventive treatment theory in disease prevention and rehabilitation, and forecasts the research model of Jingjin rehabilitation medicine from an integrative perspective of Chinese and western medicine. This study aims to improve the rehabilitation application thinking of Jingjin therapy and enrich the application methods and treatment approaches of TCM rehabilitation medicine.

Survey of Applicable Methods for Determining Viscoelastic Effects in Ferroelectric and Antiferroelectric Chiral Liquid Crystals.

Viscosity, elasticity, and viscoelastic properties are one of the most fundamental properties of liquid crystalline materials; the main problem in determining these properties is the multitude of physical parameters needed to determine the values of elasticity and viscosity constants. In this paper, a number of different measurement methods for the complete characterization of viscoelastic properties for smectic liquid crystalline materials and their mixtures are analyzed, both theoretically and experimentally. The way in which viscoelastic material constants are determined depends mainly on the application/purpose of the materials under study. The subject of this work was to review the methods used to determine viscoelastic effects in ferroelectric and antiferroelectric chiral liquid crystals, their mixtures, composite materials, and even in dielectric systems, which would bear the hallmark of a universal method allowing the application of sufficiently low electric fields. In the case of chiral liquid crystals with ferroelectric and antiferroelectric phases and their subphases, the following assumption applies: fulfilment of Hooke's law (in the case of elastic coefficients) and preservation of laminar flow (in the case of viscosity coefficients).

Synergistic effects of soil and foliar nano-biochar on growth, nitrogen metabolism and mineral uptake in wheat varieties

Soil amendment and foliar application of nanobiochar (NBC: a unique nanomaterial) may enhance soil fertility which ensures that nutrients are available to plants, and increase crop production because it is a suitable source of macro- and micronutrients. From this study, NBC induced modification in two wheat varieties (Akbar, Zincol) yield, growth, physio-biochemical and ionic profiles have been studied. The soil application of nanobiochar was applied in four concentrations [control (0 %), S1 (1 %), S3 (3 %), and S5 (5 %)] at the sowing stage while after 30 days of germination, the foliar application of same NBC concentrations with surfactant (0.1 % Tween-20) was applied in the pots. Each treatment has three replications and experiment was arranged in a completely randomized design (CRD). Results indicated that growth attributes, physio-biochemical parameters and ion contents were significantly increased in both varieties than their respective controls with Akbar variety exhibiting better improvement in Akbar. However, the application of NBC increased the plant height, shoot–root dry biomass and shoot length at the S3F3 level (NBC in soil 5 % + NBC as foliar 3 %) while root length, plant and shoot fresh weight at the S5F5 level (NBC in soil 5 % + NBC as foliar 5 %) root fresh weight and plant dry weight S3F1 level (NBC in soil 3 % + NBC as foliar 1 %), leaf area at S3F3 level (NBC in soil 3 % + NBC as foliar 3 %), number of tillers at S1F5 level (NBC in soil 1 % + NBC as foliar 5 %). On the other hand, both methods of NBC applications significantly enhanced the photosynthetic pigments in both varieties but the Zincol variety showed the highest rate of pigments. Moreover, both applications of NBC significantly affect the primary metabolites (total soluble sugar, protein, and free amino acids), secondary metabolites (phenolic and flavonoid content), antioxidants (Catalase and peroxidase) and nitrogen metabolic enzyme (Nitrite and Nitrate) of both varieties with comparatively higher rate in the Akbar variety. In conclusion, these results showed that the combined applications of NBC as soil and foliar form could be used as a suitable source of fertilizer because of its beneficial effects and high nutritional content.

Creating Instagram Feeds as Arts and Culture Weeks Promotional Media with Canva Application and EPIC Method

This study aimed to develop an engaging Instagram feed design to enhance visitor participation at the Cultural Arts Week event. The research employed a case study method with a qualitative approach. The sample consisted of 16 respondents, including the chief executive of Cultural Arts Week, 2 computer experts, 2 graphic design experts, and 11 visitors to the event, all of whom were students at the IPB Vocational School. The effectiveness of the design was assessed using the EPIC method, which evaluates Empathy, Persuasion, Impact, and Communication. The results indicated a score of 4.25 for Empathy, 4.1 for Persuasion, 4.12 for Impact, and 4.27 for Communication, yielding an overall EPIC Rate of 4.18.

Pengaruh Faktor Emosional dan Faktor Rasional Terhadap Keputusan Pedagang dalam Menggunakan Jasa Perbankan Syariah: Studi Kasus pada Pedagang Kecamatan Serbajadi Kabupaten Serdang Bedagai

The purpose of this study is to identify emotional factors and rational factors of traders in Serbajadi District, Serdang Bedagai Regency when making decisions in using Islamic Banking services. This study used a quantitative approach with the distribution of questionnaires. The sample was randomly selected using proportional random sampling method and Slovin algorithm with a total of 88 traders. The data obtained were processed using the SPSS 27 application and multiple linear regression analysis methods used. The results obtained partially, the emotional factor variable (X1) has a negative and significant effect on the decision of Traders (Y) in using Islamic banking services. And the rational factor variable (X2) has an influence and is significant on the decision of traders (Y) in using Islamic banking services. Simultaneously, emotional factors (X1) and rational factors (X2) influenced traders' decisions (Y) in using Islamic banking services, amounting to 58.8% and other factors not included in the research model impacted the remaining 41.2%.

Current Collector Primers with Improved Physical and Electrochemical Properties

Lithium-ion batteries are the dominant technology for powering the growing markets of electric vehicles, consumer electronics, and grid storage. However, to meet the increasing demands for higher energy density, faster charging, lower cost, and longer cycle life, continued research of new materials and designs are required. One of the key components that affects the performance and durability of lithium-ion batteries is the current collector, which provides a conductive substrate for active materials. The interfacial conductivity, adhesion, and corrosion resistance of these foils is largely dictated by their native oxide surface layer. To improve any of these features, specialized primers may be applied prior to electrode manufacturing, presenting a unique electrode/active material interface. For instance, carbon-coatings may be applied to aluminum to improve the conductivity and adhesion of lithium iron phosphate (LFP) formulations. These carbon coatings are limited in their cost, thickness, and performance, particularly in next generation cell designs and application methods. PPG is exploring novel current collector coating technologies addressing the physical, electrochemical, and stability requirements of these chemistries and manufacturing process. In this presentation, we will elaborate on coatings development and the effect that novel primer layers have on mechanical properties and single-layer pouch cell cycle life.

Bee-Inspired Healing: Apitherapy in Veterinary Medicine for Maintenance and Improvement Animal Health and Well-Being.

This review aims to present current knowledge on the effects of honey bee products on animals based on in vivo studies, focusing on their application in clinical veterinary practice. Honey's best-proven effectiveness is in treating wounds, including those infected with antibiotic-resistant microorganisms, as evidenced in horses, cats, dogs, mice, and rats. Propolis manifested a healing effect in numerous inflammatory and painful conditions in mice, rats, dogs, and pigs and also helped in oncological cases in mice and rats. Bee venom is best known for its effectiveness in treating neuropathy and arthritis, as shown in dogs, mice, and rats. Besides, bee venom improved reproductive performance, immune response, and general health in rabbits, chickens, and pigs. Pollen was effective in stimulating growth and improving intestinal microflora in chickens. Royal jelly might be used in the management of animal reproduction due to its efficiency in improving fertility, as shown in rats, rabbits, and mice. Drone larvae are primarily valued for their androgenic effects and stimulation of reproductive function, as evidenced in sheep, chickens, pigs, and rats. Further research is warranted to determine the dose and method of application of honey bee products in animals.

Monitoring the Corrosion Resistance of Cold-Spray Coatings with Membrane-Based Sensors

Ensuring the management of gas transportation infrastructure requires the monitoring of internal corrosion within pipelines. The utilization of membrane-based electrochemical sensors is a promising advancement in corrosion risk monitoring. These sensors demonstrate an ability to operate within humidified gas environments, previously inaccessible to conventional electrochemical monitoring methods. Simultaneously, ongoing research is delving into novel sacrificial coatings and application methods to prolong the lifespan of existing pipeline structures and minimize associated repair costs. In this context, we broaden the application of membrane-based electrochemical sensors to investigate the response of electrodes equipped with cold-spray coatings. This examination encompasses a range of fluids exhibiting varying levels of corrosivity pertinent to natural gas pipelines. Multiple sensors with 316 stainless steel working electrodes were coated with cold spray sacrificial coating then exposed to humidified gases with differing relative humidities (RH) (5 %, 50 %, and 95 %) and condensed phases with differing salt content (deionized water and 0.1 mol kg-1 NaCl solution). Three electrochemical techniques (potentiometry, impedance spectroscopy and potentiodynamic scans) were used to monitor the corrosive environment and probe the extent of coating coverage. For the conditions studied, impedance values were extremely sensitive to changes in water content through changes in the membrane resistance (from ~1 kΩ in deionized water to ~5 MΩ with 5 % RH). Polarization resistances (Rp) consistently decreased with increasing corrosivity (~3 kΩ in deionized water to 15 GΩ with 5 % RH). Scanning electron microscopy and energy dispersive X-ray spectroscopy were used to identify the extent to which corrosion products permeated the membrane after major corrosion events.

Nuclear spin polarization of lactic acid via exchange of parahydrogen-polarized protons

Hyperpolarization has become a powerful tool to enhance the sensitivity of magnetic resonance. A universal tool to hyperpolarize small molecules in solution, however, has not yet emerged. Transferring hyperpolarized, labile protons between molecules is a promising approach towards this end. Therefore, hydrogenative parahydrogen-induced polarization (PHIP) was recently proposed as a source to polarize exchanging protons (PHIP-X). Here, we identified four key components that govern PHIP-X: adding the spin order, polarizing the labile proton, proton exchange, and polarization of the target nucleus. We investigated the last two steps experimentally and using simulations. We found optimal exchange rates and field cycling methods to polarize the target molecules. We also investigated the influence of spin relaxation of exchanging protons on the target polarization. It was found experimentally that transferring the polarization from protons directly bound to the target X-nucleus (here 13C) of lactate and methanol using a pulse sequence was more efficient than applying a corresponding sequence to the labile proton. Furthermore, varying the concentrations of the transfer and target molecules yielded a distinct maximum 13C polarization. We believe this work will further help to understand and optimize PHIP-X towards a broadly applicable hyperpolarization method.

A New Generalization of the Inverse Generalized Weibull Distribution with Different Methods of Estimation and Applications in Medicine and Engineering

Limitations inherent to existing statistical distributions in capturing the complexities of real-world data often necessitate the development of novel models. This paper introduces the new exponential generalized inverse generalized Weibull (NEGIGW) distribution. The NEGIGW distribution boasts significant flexibility with symmetrical and asymmetrical shapes, allowing its hazard rate function to be adapted to many failure patterns observed in various fields such as medicine, biology, and engineering. Some statistical properties of the NEGIGW distribution, such as moments, quantile function, and Renyi entropy, are studied. Three methods are used for parameter estimation, including maximum likelihood, maximum product of spacing, and percentile methods. The performance of the estimation methods is evaluated via Monte Carlo simulations. The NEGIGW distribution excels in its ability to fit real-world data accurately. Five medical and engineering datasets are applied to demonstrate the superior fit of NEGIGW distribution compared to competing models. This compelling evidence suggests that the NEGIGW distribution is promising for lifetime data analysis and reliability assessments across different disciplines.

Novel Method to Measure Volumes of Retinal Specific Entities.

Objectives: The aim of this study is to describe and validate an optical-coherence-tomography (OCT)-based method to easily calculate specific volumes, addressing the limitations of current OCT software in automating volumetric analysis for specific entities in retinal pathologies. Methods: After manually drawing the specific entity on linear OCT scans using the calliper function and automated measurement of its area, the following formula was used for volumetric calculation: Volume [mm3] = ∑area [mm2] × OCT-scan distance [mm]. Retinal volume (RV) was measured by two independent observers in eyes with a normal foveal profile (NFP) and was compared with the automated measurements performed by the OCT software (Engineering GmbH, Heidelberg, Germany); the same process was repeated for the volume of the foveal cavity (FC) or foveoschisis (FS) in eyes with lamellar macular holes (LMHs). Power calculations were conducted to ensure adequate sample size. The measurements were re-acquired after six weeks. Intra- and inter-observer variability as well as comparison to automated RV calculations were analysed. Results: This study included a total of 62 eyes divided into two groups: the NFP (30 eyes) and LMH (32 eyes) groups. The Bland-Altman plots showed a high degree of agreement in both groups for inter-observer and intra-observer agreement. In addition, in the NFP group, a high degree of agreement was demonstrated between human observers and the OCT software (Spectralis). Conclusions: An easy, reliable, and widely applicable method to calculate volumes is described and validated in this paper, showing excellent inter- and intra-observer agreement, which can be applied to any entity requiring a specific study in the context of retinal pathologies.

Exploring bone density analysis on routine CT scans as a tool for opportunistic osteoporosis screening

The primary aim of this study was to evaluate computed tomography (CT)-based bone density analysis at the level of thoracic vertebra 12 (Th12) as a screening method for decreased bone density in patients admitted to the intensive care unit (ICU). Interobserver variability was analyzed. Secondary aims were to assess the prevalence of CT-based low bone density upon ICU admission in a cohort of COVID-19 patients and to assess the potential effect of long-term ICU stay on bone density in these patients. Retrospective single-center cohort study. ICU of the Leiden University Medical Center (LUMC), the Netherlands. Patients admitted to the ICU of the LUMC between March 1st, 2020 and February 1st, 2022 with a diagnosis of COVID-19, and a length of ICU stay of ≥ 21 days. In the included patients both baseline chest CT scans (obtained upon ICU admission) and follow-up chest CT scans (obtained ≥ 21 days after ICU admission) were available for analysis. A total of 118 CT scans in 38 patients were analyzed. There was a good interobserver variability, with an overall mean absolute difference (between measurements of three observers) of 9.7 Hounsfield Units (HU) and an intraclass correlation coefficient (ICC) of 0.93 (95% CI 0.88–0.96). The effect of intravenous contrast administration on bone density measurements was small (+ 7.5 HU (95% CI 3.4–11.5 HU)) higher in contrast enhanced CT images compared to non contrast enhanced CT images). Thirty-seven percent of patients had a bone density < 140 HU, suggestive of osteoporosis. No significant difference was found between bone density upon ICU admission and bone density at follow-up (≥ 21 days after ICU admission). Vertebral CT-based bone density analysis using routine CT scans is an easily applicable method to identify ICU patients with decreased bone density, which could enable enrollment in osteoporosis prevention programs. A high prevalence of low bone density was found in our cohort of ICU patients. There were no changes observed in bone density between baseline and follow-up measurements.