Critical Value Research Articles

A Study on the Establishment of Alternative Verification Standard of Ballistic Ttest for Armored Steel Arc Welding Procedure

The final goal of this study is to secure the basis for establishing a domestic test standard such that the H-plate ballistic test for weld verification required by TACOM Drawing 12479550 can be replaced with the Charpy impact test. The core of this study is to prove the correlation between the ballistic test and the impact test. As a result of ballistic test specimens manufactured with various welding parameters, the generated crack length showed a correlation of approximately 78% with impact toughness. In addition, cracks occurred at the weld toe and propagated along the fusion line irrespective of any variables. Therefore, the notch location of the impact test specimen was determined by the fusion line. Moreover, experiments proved that impact toughness did not change significantly when changing non-essential welding variables. The impact toughness of the fusion line critical values of MIL-A-12560 and MIL-A-46100 materials used in this study were 50 J and 22 J, respectively. This value exceeded the impact toughness management standard for the base material. Therefore, the passing threshold value was ultimately determined to be above the impact toughness threshold of the base material.

Shelf Life and Functional Quality of Almond Bagasse Powders as Influenced by Dehydration and Storing Conditions.

Almond bagasse resulting after the production of almond-based drinks represents a promising by-product with potential for use as a functional ingredient. To facilitate its utilization, the stability of this material can be achieved through dehydration processes such as hot air drying or freeze-drying. Nevertheless, owing to its high fat content, almond bagasse is prone to lipid oxidation, which could result in undesirable quality. Therefore, the objective of this work was to assess the impact of dehydration (by hot air drying at 60 and 70 °C and by freeze-drying) and storage (at room temperature and in accelerated conditions) on the functional quality and stability of almond bagasse powder. Throughout the dehydration process, it was observed that antioxidant compounds were preserved without significant differences among dehydration treatments. These compounds increased over the storage period, especially in the samples treated with hot air. Regarding antiradical capacity, the hot-air-dried samples showed higher values than the freeze-dried ones, although in all cases, it increased during storage. For total phenols in samples air-dried at 70 °C, increases of more than 50% were observed. The acidity and peroxide index were increased in the extended storage period, although they did not reach critical values. Samples stored for 180 days showed peroxide values ranging from 10 to 12.8 meq O2/kg dry matter for samples stored at room temperature and from 14.7 to 23 meq O2/kg dry matter for samples subjected to accelerated storage.

Study on the dynamic thermal response of phase change material integrated wall under indoor-outdoor dual thermal disturbances

The study mainly explored the dynamic thermal response of phase change material integrated wall (PCMW) under indoor-outdoor dual thermal disturbances (IODTD). A dual wave thermal disturbance dynamic boundary condition was proposed for PCMW based on the outdoor meteorological data and typical solar energy building analytical models of Lhasa, Yinchuan and Xi'an in China. The influence of different construction modes on the thermal performance of PCMW was numerically investigated by the sensible heat capacity method under IODTD. Then determined the crucial thermophysical parameters of PCM and analyzed the variation characteristics of temperature and heat flux fields of PCMW. The heat transfer frequency responses of different walls to outdoor thermal disturbances were calculated by the harmonic response method. The results indicated that the optimal location of PCM was on the interior side of the wall, and the critical values of phase change temperature and latent heat were 16 °C and 120 kJ/kg, respectively. It presented the maximum temperature and heat flux were 10 % and 36.2 % greater than ordinary walls (OW). Compared with OW, the attenuation and delay time of PCMW on outdoor sol-air temperature wave performed significantly, which plotted a higher decrement factor and longer time lag under external disturbances of different orders.

Effect of waste dumpsite on the surface and groundwater supplies using water quality index in Afikpo south local government area, Ebonyi state

The research examined the effect of waste dumpsite on the surface and groundwater supplies using water quality index (WQI) in Afikpo South Local Government Area of Ebonyi State. Fifteen samples were drawn from fifteen locations. The samples were analyzed using standard methods. The results of the analyses were compared with the World Health Organization (WHO) drinking water standard. The WQI of the water samples were calculated and compared with the classification of water quality status. The results showed that the pH of the water samples ranged 4.6±0.047 – 6.70±0.090, EC 7.26±1.63 – 2450±4.32, Turbidity 0.50±0.082 – 2.00±0.094, TDS 23.10±0.047 - 1830±17.00, Alkalinity 45±0.47 - 2080±4.71, Total Hardness 4±0.47 – 170±0.94, DO 5.07±0.012 – 7.72±0.016, BOD 0.4±0.047 – 12.8±0.082, NO3 - 1.14±0.009 – 32.69±0.047 and 0.09±0.00 – 15.6±0.028. The results showed that the pH, Turbidity, Total Hardness, NO3 - were all below the WHO drinking water standard. All the locations of the water samples showed some levels of acidity. Apart from location MB that recorded high levels of TDS and Alkalinity every other location was below the WHO permissible limit of drinking water standard. The results of the analysis also revealed that the WQI value of the water was 57.92 and this was below the critical value of 100. From the findings, all the water samples need to be treated with alkali to reduce the low pH while the water samples generally need to be given comprehensive treatment before usage.

Analysis of the Effect of an Open Hole on the Buckling of a Compressed Composite Plate.

This paper investigates the effect of an open hole on the stability of a compressed laminated composite plate. The study was carried out in two ways: using experimental tests and numerical analysis. As a result of the experiment, the buckling form and path of the plate were recorded. The form of buckling was determined using the ARAMIS non-contact measurement system. The critical load value was determined from the working path using the approximation method. The experimental results were verified by numerical analysis based on the finite element method. FEM investigations were carried out in terms of a linear eigenproblem analysis. This allowed the bifurcation load and the corresponding buckling form of the numerical model of the plate to be determined. Investigating the effect of the hole in the compressed plate at a critical state showed high agreement between the proposed test methods. No clear effect of the hole size on the buckling of the plate was observed. In contrast, a clear effect of the hole on the critical load value was determined. The maximum decrease in the critical load value was 14%. The same decrease was observed for the stiffness of the post-critical characteristics. It was shown that the [45|-45|90|0]s composite plate had more than three times lower strength compared to [0|-45|45|90]s and [0|90|0|90]s. The novelty of this article is the development of a research methodology based on new interdisciplinary research methods for describing the influence of the central hole on the stability of compressed composite plates. The ABAQUS system was used for the numerical analysis.

Endocrine disrupting chemicals in Italian drinking water systems: Insights from a three-year investigation combining chemical and effect-based tools

Drinking water quality can be compromised by endocrine-disrupting chemicals (EDCs). Three phenolic compounds [bisphenol A (BPA), nonylphenol (NP), and 4-octylphenol (OP)] and three hormones [17β-estradiol (E2), estrone (E1), and 17α-ethinylestradiol (EE2)] were analyzed as EDCs potentially occurring in source and drinking water from three full-scale drinking water treatment plants (DWTPs) in the Romagna area (Italy) by a combined approach of HPLC-MS/MS target analysis and effect-based tests for estrogenicity and genotoxicity. The EDC removal efficiency was evaluated at different steps along the treatment process in the most advanced DWTP. NP prevailed in all samples, followed by BPA. Sporadic contamination by OP and E1/E2 appeared only in the source waters; EE2 was never detected. No estrogenic or genotoxic activity was found, except for two samples showing estrogenicity well below the effect-based trigger value suggested for drinking water safety (0.9 ng/L EEQ). BPA and NP levels were largely below the threshold value; however, increases were observed after the intermediate steps of the treatment chain. The good quality of the water relied on the last step, i.e. the activated carbon filtration. DWTPs may represent an extra source of EDCs and monitoring chemical occurrence at all steps of the process is advisable to improve efficiency.

Surface Degradation of Ion-releasing Restorative Materials With Cariogenic Challenge.

This study examined the influence of cariogenic environments on the surface roughness of ion-releasing restorative materials (IRMs). Custom-made stainless steel molds with holes of 5 mm × 2mm were used to fabricate 60 disc-shaped specimens of each of the following materials: Activa Bioactive (AV), Beautifil Bulk Restorative (BB), Cention N (Bulk-fill) (CN), and Filtek Z350XT (FZ) (Control). Baseline surface roughness (Ra) measurements were obtained using an optical 3D measurement machine (Alicona Imaging GmbH, Graz, Austria). The specimens were then randomly divided into five subgroups (n=12) and exposed to 10 ml of the following mediums at 37°C: distilled water (DW), demineralization solution (DM), remineralization solution (RM), pH cycling (PC) and air (AR) (control). Ra measurements were again recorded after one week and one month, followed by statistical evaluations with two-way analysis of variance (ANOVA) to determine interactions between materials and mediums. One-way ANOVA and post hoc Games Howell tests were performed for intergroup comparisons at a significance level of 0.05. Mean Ra values ranged from 0.085 ± 0.004 (µm) to 0.198 ± 0.001 µm for the various material-medium combinations. All IRMs showed significant differences in Ra values after exposure to the aqueous mediums. The smoothest surfaces were observed in the AR for all materials. When comparing materials, AV presented the roughest surfaces for all mediums. All IRM materials showed increased surface roughness over time in all cariogenic environments but were below the threshold value for bacterial adhesion, except for AV 1-month post immersion with pH cycling. Therefore, besides AV, the surface roughness of IRMs did not deteriorate to an extent that it is clinically relevant.

Analisa Kebisingan Pada Alat Berat Wheel Loader Wa-350 Berdasarkan Perbandingan Jarak 50, 100, 150 Cm Dan Kapasitas

Wheel loader is a tool that facilitates work by using hydraulic energy. Wheel loader testing is carried out by looking for noise data arising in the combustion chamber. There are several stages that must be done, namely the first step is to prepare a sound level meter as a noise detection device for heavy equipment, wheel loader, then take measurements with several variations in the distance between the combustion chamber and the sound level meter. In the next step we can find out the noise level read at the sound level meter with ideal, medium, and maximum rotation on the WA-350 wheel loader. So that the Noise Threshold Value according to Permenaker No. per-51 / MEN / 1999, ACGIH, 2008 and SNI 16-7063-2004 is 85 dB. So the noise produced by the Wheel Loader above the NAB Permenaker 104.7dB can cause tingling, unwell, hearing saturation, stomach pain, and circulatory problems. It is recommended that workers are required to use earmuffs or ear muffs.

Diagnostic utility of point-of-care ultrasound and optical coherence tomography for papilloedema in children: a prospective pilot study

Background/AimsPapilloedema is an important sign of serious neurological disease, but it can be difficult to detect on funduscopy. The purpose of this study was to determine the diagnostic accuracy of...

Derivation and validation of a quantitative risk prediction model for weaning and extubation in neurocritical patients.

Patients with severe neurological conditions are at high risk during withdrawal and extubation, so it is important to establish a model that can quantitatively predict the risk of this procedure. By analyzing the data of patients with traumatic brain injury and tracheal intubation in the ICU of the affiliated hospital of Hangzhou Normal University, a total of 200 patients were included, of which 140 were in the modeling group and 60 were in the validation group. Through binary logistic regression analysis, 8 independent risk factors closely related to the success of extubation were screened out, including age ≥ 65 years old, APACHE II score ≥ 15 points, combined chronic pulmonary disease, GCS score < 8 points, oxygenation index <300, cough reflex, sputum suction frequency, and swallowing function. Based on these factors, a risk prediction scoring model for extubation was constructed with a critical value of 18 points. The AUC of the model was 0.832, the overall prediction accuracy was 81.5%, the specificity was 81.6%, and the sensitivity was 84.1%. The data of the validation group showed that the AUC of the model was 0.763, the overall prediction accuracy was 79.8%, the specificity was 84.8%, and the sensitivity was 64.0%. These results suggest that the extubation risk prediction model constructed through quantitative scoring has good predictive accuracy and can provide a scientific basis for clinical practice, helping to assess and predict extubation risk, thereby improving the success rate of extubation and improving patient prognosis.

Shift in the quantitative relationship between sedimentary records and catchment floods influenced by dam construction

Interpretation of sedimentary records is a crucial method for studying paleo-floods. However, the response intensity of sedimentary records to floods may be altered by reservoir storage. Therefore, depicting flood intensity in sedimentary records and alterations in the response relationship is the primary challenge in paleo-flood reconstruction. This study used the Yalu River catchment–estuary–coast as the research area and quantitatively reconstructed the response relationship between sediment grain size composition and flood intensity. This was conducted through a combination of forward simulation of the HYDROTREND hydrological model and reconstruction of sedimentary records, as well as evaluating the impact of reservoir regulation on the quantitative relationship. The findings showed that the lower Yalu River channel and tidal flat were both efficient at preserving flood records. However, there were significant differences in the response of different geomorphic units to floods. The river channel showed a significant increase in the coarse-sensitive component, whereas the tidal flat exhibited a substantial increase in the fine-sensitive component. Further study showed that there was a significant logarithmic relationship between the content of the fine-sensitive fraction and flood intensity. The sensitivity of the fine-sensitive fraction towards small floods was much higher than that toward extreme floods. In addition, reservoir construction caused a significant shift in the relationship between flood intensity and flood-related sensitive sediment fractions. Consequently, the reconstructed flood intensities of the pre-dam construction showed diverse levels of magnification based on the quantitative relationship between the sedimentary record and flood intensity of the post-dam. Meanwhile, this shift led to an increase in flood intensity corresponding to the critical value of the flood record that could be detected: from floods with a return period exceeding two years before dam construction to floods with a return period exceeding five years after dam construction. This study has quantitatively reconstructed the relationship between sediment grain size fractions and flood intensity and assessed the impact of reservoir construction on the quantitative relationship. It has also provided new ideas for more accurate reconstruction of paleo-flood intensity changes in the future.

COVID-19 and multiple sclerosis: is there a connection?

Multiple sclerosis (MS) is a chronic immune-mediated disease of the central nervous system, which is based on inflammatory demyelination and neurodegeneration. Over the course of the COVID-19 pandemic, there has been a perception that the virus has an effect on the course of immune processes. The questions of whether the frequency of autoimmune diseases, including the nervous system, and their course has changed have been discussed. Aim of the study was to assess the clinical and epidemiological characteristics of MS during the COVID-19 pandemic from 01.01.2020 to 01.01.2023 in Novosibirsk. In the course of our work, we studied the incidence of MS and the features of the clinical picture of the debut of MS associated with COVID-19 infection. Material and methods. The study included 628 patients with MS living in Novosibirsk with the onset of the disease in the period before the pandemic from 01.01.2017 to 12/31/2019 (341 patients) and during the pandemic from 01.01.2020 to 01.1.2023 (287 patients). Results. The incidence rates of MS in Novosibirsk were calculated, it was 7.1 7.6 6.4 7.38 6.92 and 3.2 per 100 thousand population in 2017, 2018, 2019, 2020, 2021 and 2020, respectively. The average incidence of MS in the study period before the pandemic was 7.03 per 100 thousand population, during the pandemic – 5.83 per 100 thousand population (critical value of the Student’s t-test = 1.972, with a significance level of a = 0.05). When analyzing the association of clinical manifestations of the onset of MS with COVID-19, it was found that coordination disorders were observed in patients with moderate infection more often than in patients with mild infection (p &lt; 0.05; odds ratio 0.410, 95% confidence interval 0.162–1.035). No statistically significant correlation of clinical manifestations with the severity of infection was shown for patients with primary progressive MS, however, the predominance of the multi-focal nature of disease after a more severe course of COVID-19 was noted (40 %). After the first clinical demyelinating episode in the group of patients with relapsing-remitting MS, the chances of complete recovery in patients with mild infection are 2.8 times higher than in patients with moderate infection (p &lt; 0.05). Conclusions. Thus, as a result of the conducted study, the effect of COVID-19 on the change in the incidence of MS was not revealed. In the process of analyzing the clinical features of MS during the pandemic, it was found that COVID-19 infection can contribute to an unfavorable course of MS with worse recovery of neurological deficits after episodes of exacerbations, which leads to the accumulation of disability of patients.

Pulmonary Venous Index as Additional Diagnostic Criteria for Fontan Palliation

Backgroud. The results of the Fontan operation, depending on the anatomy of the pulmonary arteries, have been studied quite well. Various indices have been proposed to assess the degree of hypoplasia of the pulmonary arterial bed (Nakata, Reddy, and McGoon indexes). At the same time, an obstruction of pulmonary venous blood return may be considered as a contraindication to Fontan operation. Aim of the Study. To present an optimal method for pulmonary venous index (PVI) calculation based on computed tomography angiography (CTA) enhancement of the heart data in patients with a functional single ventricle. Materials and Methods. 63 patients with a functional single ventricle (SV) underwent CTА (Philips, Brilliance iCT) before the Fontan operation. Axial sections were reconstructed to a thickness of 0.75–3 mm using soft tissue and lung filters, followed by postprocessing of the data (Horos and OsiriX software) and construction of multiplanar and 3D images. The diagnoses were presented by various types of SV of the heart. The age of the patients ranged from 3 to 30 years (median 7 years). Comparison of PVI was carried out in patients of two groups: those who survived the intervention (n = 55 patients) and those who died (n = 8). The evaluation of the pulmonary veins (PV) and the calculation of the pulmonary venous index (PVI) were carried out based on the measurement of each pulmonary vein at 2 levels (at the level of the orifices and bifurcation). The calculation of the PVI was carried out according to the formula: the sum of the cross-sectional area of the main pulmonary veins, related to the body surface area. 3 variants of PVI calculation were compared: taking into account the values of the PV areas at the level of the orifices, the bifurcation, and the sum of the minimum areas of each of the PVs. Results. In the group of survived patients, the median PVI at the level of the PV orifices was 292 mm/m2, and in the group of deceased, it was 242 mm/m2p=0.0326; at the level of PV bifurcation in the group of survivors, it was 299 mm/m2, and in the group of dead patients, it was 281 mm/m2p=0.0776; the minimum PVI was 257 mm/m2 in the survivor group and 218 mm/m2 in the deceased group p=0.006. An ROC analysis performed to determine the critical value of the minimum PVI affecting survival after Fontan operation revealed that PVI measured taking into account the minimum dimensions of the areas of the PV is a significant risk factor for death after Fontan operation p=0.00015, with its value (cutoff) &lt;233.5 mm2/m2. Conclusion. The value of the minimum PVI can be an important morphological indicator of the state of PV blood return and serve as an additional criterion in determining indications for the Fontan operation.

Mechanical properties of Q355 hot-rolled steel during the entire fire process

This study conducts steady-state tests to comprehensively examines the mechanical properties of Q355 hot-rolled steel throughout the entire fire process, including the cooling stage. Results show that the mechanical properties at the fire-cooling stage are influenced by both the peak heating temperature (Tp) and the tensile test temperature (Tt). Within a specific threshold value of Tp, the mechanical properties at the cooling stage of fire resemble those observed in the heating stage. However, when Tp surpasses this threshold value, notable disparities emerge between the mechanical properties of steel at the cooling and heating stages. The threshold temperatures for elastic modulus, ultimate strength, and ultimate strain are all 600 °C, while that for the yield strength f0.2 is 400 °C. A cooling stage influence coefficient is used to quantitatively portray the variance in mechanical properties between the cooling and heating stages of fire. Calculation formulas for the fire cooling stage influence coefficients were provided for the elastic modulus, yield strength f0.2, ultimate strength, and ultimate strain, respectively. Finally, a constitutive model for the entire fire process of Q355 steel was established.

Audio-Based Vehicle Detection System: Enhancing Safety for Bicycle Riders

To enhance the safety of bicycle riders an android mobile application was developed that utilizes real-time audio analysis to detect approaching vehicles and alert the riders when there is a safety issue. The application employs a CNN lite model to detect the presence of the vehicle. The CNN model was trained on a dataset of 0.5-second audio clips of vehicle and non-vehicle sounds. The root mean square value of the audio clip is calculated to figure out the approaching vehicles. Based on the model prediction and the root mean square value of amplitude, the application issues alerts to the user. Three alert levels are defined, ranging from level one for low amplitude to level three for high amplitude. The alert types are audio, visual and vibration. Users can customize and adjust the alert types and threshold values within the predetermined range according to their preferences. The evaluation of the model revealed favourable results, as indicated by low loss and high recall and precision metrics, affirming the efficacy of the model for accurately detecting vehicles. The ability of the model to proactively detect and alert bicycle riders of incoming vehicles, enable the users to take timely actions to prevent potential hazards and positions the application as a crucial and effective lifesaving tool.

New candidate SNPs for genetic association with Alzheimer's disease: a linkage disequilibrium analysis for the FCGRIIB and PILRA genes.

Two new SNPs have been recently associated to Alzheimer's disease in African American populations: FCGRIIB rs1050501 C/T, and PILRA rs1859788 A/G. The risk of Alzheimer's disease in FCGRIIB C and PILRA A allele carriers is three times higher than in non-carriers. However, the association between these and other single nucleotide polymorphisms (SNPs) has not been assessed. Linkage disequilibrium analysis, with r= 0.8 as a threshold value, was used to impute new candidate SNPs, on genomic data from both genes in 26 populations worldwide (n= 2504) from the 1000Genomes database. Four SNPs (rs13376485, rs3767640, rs3767639 and rs3767641) were linked to rs1050501 and one (rs2405442) to rs1859788 in the whole sample. Five novel SNPs could be associated with Alzheimer's disease susceptibility and play a causal role, even if none of them are exon variants since their potential roles in the regulation of gene expression.

A non-stationary transformer-based remaining useful life prediction method for proton exchange membrane fuel cells

The remaining useful life (RUL) is one of the critical factors for proton exchange membrane fuel cells (PEMFCs), as it is hindering the commercialization of PEMFCs in various fields. In this research, a novel deep learning (DL) algorithm, i.e. the Non-stationary Transformer is newly applied to the RUL prediction of a PEMFC stack. For better prediction accuracy, the discrete wavelet transform (DWT) is utilized to denoise the original data before the normalization process. Prediction results of the proposed Non-stationary Transformer-based PEMFC RUL prediction method are analyzed under different lengths of training datasets, under different time steps ahead prediction, and for different PEMFC End of Life (EoL) threshold values and compared to those of other DL-based prediction methods including the long short-term memory (LSTM)-based and echo state network (ESN)-based methods. Results show that the proposed method outperforms the LSTM-based and ESN-based methods for all different cases studied in this research.

Dual solutions of Darcy-Forchheimer radiative-convective magneto-nanofluid flow over an exponentially stretching/shrinking surface: Stability and entropy generation analysis

A numerical investigation was conducted to examine the existence of dual solutions over exponentially stretching or shrinking permeable surfaces. The study aimed to analyze the impact of thermal and second-order velocity slip on magnetohydrodynamic (MHD) mixed convective radiative nanofluid flow within a Darcy-Forchheimer porous medium while considering heat generation. Two distinct types of nanofluids, namely Cu-water and TiO 2/water, were employed in the investigation. To address the nonlinear partial differential equations (PDEs), similarity transformations were utilized to transform them into a system of ordinary differential equations (ODEs). The resulting coupled higher-order nonlinear ODEs were then solved using a MATLAB-based boundary value algorithm known as bvp4c. Two distinct solutions are observed within a restricted range of the stretching/shrinking parameter ξ ( ξ > ξ c ) and suction parameter S ( S > S c ), terminating respectively at ξ = ξ c or S = S c . The critical values are identified as ξ c = − 1.1952 ( Cu − water ) , − 0.9304 ( Ti O 2 − water ) and S c = 1.6437 ( Cu − water ) , 1.8900 ( Ti O 2 − water ) , maintaining the fixed values of the remaining physical parameters. Notably, the critical value for Cu-water is lower than that of TiO 2-water. Moreover, in both solution branches, the range of skin-friction coefficient and local Nusselt number for Cu-water surpasses that of TiO 2-water. An evaluation of the temporal stability of these solutions reveals that only the first solution remains stable. This is supported by the positivity of the smallest eigenvalues ( γ 1 > 0 ), indicating stability. Conversely, for the second solution, the smallest eigenvalues ( γ 1 < 0 ) are negative, signifying its instability. Also, Cu-water nanofluid exhibits higher fluid velocity and lower fluid temperature than TiO 2-water nanofluid for stable solutions and the opposite behavior for unstable solution branches. Significantly, within the initial solution branch, there is an escalation in velocity profiles attributed to the magnetic parameter, Grashof number, porous parameter, and first- and second-order velocity slip parameter. Conversely, a decrease is observed for the Forchheimer number, while the opposite holds true for the second solution branch. For both solution branches, the temperature profiles experience a reduction due to thermal slip and stretching/shrinking parameters, whereas enhancements are noted for thermal radiation and heat generation parameters. Furthermore, an increase in the suction parameter leads to elevated skin friction coefficient and local Nusselt number in the first stable solution, thereby promptly improving heat transfer efficiency. Moreover, improvements in entropy generation arise from factors such as thermal radiation, magnetic field, and nanoparticle solid volume fraction, presenting opportunities to optimize heat transmission in cooling and heating systems.

Influencing Factors of Constipation in Elderly Patients With Intracerebral Hemorrhage: Implication for Clinical Care.

Background: Constipation is common in elderly inpatients with intracerebral hemorrhage. This study aimed to construct a model for predicting the risk of constipation in elderly inpatients with intracerebral hemorrhage and to provide reference for formulating targeted intervention measures. Methods: Elderly patients with intracerebral hemorrhage who were treated in the department of Neurosurgery of a third-class hospital in Suzhou from January 2018 to September 2023 were included. Clinical data of patients with and without constipation were compared. Logistic regression analysis was used to explore the influencing factors of constipation in elderly patients with intracerebral hemorrhage, and R software was used to construct a line chart model to verify its predictive effect. Results: A total of 504 elderly patients with intracerebral hemorrhage were included. The incidence of constipation in elderly patients with cerebral hemorrhage was 63.9%. Logistic regression analysis showed that GCS score (OR = 1.094, 95%CI: 1.019∼1.174), hypertension (OR = 2.911, 95%CI: 1.797∼4.715), use of dehydrating agent (OR = 3.794, 95%CI: 2.337∼6.158), surgical treatment (OR = 3.986, 95%CI: 2.339∼6.793), use of sedative drugs (OR = 4.212, 95%CI:2.386-7.435), and limb paralysis (OR = 6.313, 95%CI:3.689∼10.803) were the independent risk factors for constipation in elderly patients with intracerebral hemorrhage. The area under the ROC curve of the prediction model was 0.872 (95%CI: 0.8401∼0.9033), the best critical value was 0.705, the sensitivity was 0.748, and the specificity was 0.857. Conclusion: The constipation risk prediction model of elderly patients with cerebral hemorrhage has good differentiation and calibration, which is helpful for health care providers to identify the risk of constipation in elderly patients with intracerebral hemorrhage.

Chaotic Dynamics of a Duffing Oscillator Subjected to External and Nonlinear Parametric Excitations With Delayed Feedbacks

Abstract Duffing oscillator with delayed feedback is widely used in engineering. Chaos in such system plays an important role in the dynamic response of the system, which may lead to the collapse of the system. Therefore, it is necessary and significant to study the chaotic dynamical behaviors of such systems. Chaotic dynamics of the Duffing oscillator subjected to periodic external and nonlinear parameter excitations with delayed feedback are investigated both analytically and numerically in this paper. With the Melnikov method, the critical value of chaos arising from heteroclinic intersection is derived analytically. The feature of the critical curves separating chaotic and nonchaotic regions on the excitation frequency and the time delay is investigated analytically in detail. Under the corresponding system parameters, the monotonicity of the critical value to the excitation frequency, displacement time delay, and velocity time delay is obtained rigorously. The chaos threshold obtained by the analytical method is verified by numerical simulations.