Positive Load Research Articles

Factors associated with cytomegalovirus infection in antineutrophil cytoplasmic antibody-associated vasculitis: Anarrative review.

Patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV) are vulnerable to opportunistic infections, including cytomegalovirus (CMV) infection. This narrative review aims to identify factors associated with CMV infection in patients with AAV. The literature review was conducted on Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane, PubMed, Scopus, and Web of Science. The start date of the literature search was unrestricted and the end date was February 2022. CMV infection was defined as (a) CMV pp65 antigenemia or positive CMV DNA viral load by polymerase chain reaction or CMV detection on histological specimens, with associated signs and symptoms compatible with CMV infection; (b) presence of CMV clinical syndrome (defined as presence of compatible symptoms and signs and documentation of CMV by biopsy by virus isolation, rapid culture, immunohistochemistry, or DNA in biopsy material as defined by the CMV Drug Development Forum); and (c) CMV infection as coded by the International Statistical Classification of Diseases and Related Health Problems, 10th revision with at least one prescription for CMV treatment. We identified 4505 articles, of which three (2327 patients with AAV) were included. All studies were retrospective and only one of the three studies included only patients with AAV. Low or decreasing lymphocyte counts and higher prednisolone usage were associated with CMV infection in patients with AAV. Patients with AAV with lymphopenia and on high doses of prednisolone should be monitored closely for signs and symptoms of CMV infection, and might benefit from CMV prophylaxis. Prospective studies are urgently needed to better identify causes of CMV infections in patients with AAV.

Total Joint Arthroplasty Should Not Be Delayed in Hepatitis C Patients After Successful Treatment Achieving a Sustained Viral Load

BackgroundPreoperative treatment recommendations and optimal time to perform total joint arthroplasty (TJA) in patients with hepatitis C virus after treatment completion for achieving best outcomes have not been elucidated. We aim to determine (1) if undetectable viral load (UVL) prior to TJA leads to decreased postoperative complication rates, specifically periprosthetic joint infection (PJI), and (2) if delaying TJA after treatment completion has benefit in decreasing PJI. MethodsA retrospective review of all hepatitis C virus patients undergoing TJA at 3 academic tertiary care centers was conducted. A total of 270 TJAs performed from 2005 to 2019 were included, 125 with positive viral load at the time of surgery. The duration from completion of treatment regimen to TJA was recorded for the UVL cohort. The primary study outcome was PJI at 1-year follow-up. Secondary outcomes included in-hospital complications, mechanical revision TJA rates, and optimal time to TJA upon completion of treatment. ResultsPatients with positive viral load at the time of TJA had longer length of stay (3.9 vs 2.9 days, P < .0001) and a higher PJI rate at 1 year postoperatively (9% vs 2%, P = .02) than UVL patients. There was no difference of in-hospital complications or revision rates for mechanical etiologies. Delaying TJA after achieving a sustained virologic response did not impact PJI rates. ConclusionsSustained UVL prior to TJA is critical to minimize PJI irrespective of the treatment regimen utilized. Surgery can be performed with lower complication rates any time after achieving sustained virologic response. Level of EvidenceLevel III, prognostic retrospective cohort study.

The effects of mood induction and situational-emotional load on false memory based on misinformation paradigm with emphasis on controlling emotional bias, attention, working memory and emotional factors

Introduction: According to previous research, an individual’s mood affects selective attention and false memory, but the answer to the question of which type of mood (negative or positive) and emotional situation (negative or positive) creates the highest false memory requires further research. Aim: The present study was conducted to determine the extent and manner of the effect of mood induction and situational-emotional load on false memory based on the misinformation paradigm with emphasis on controlling cognitive and emotional factors. Method: The research was conducted with a quasi-experimental block design. Of the students of Kurdistan University in the academic year 2018-2019, 90 subjects (45 girls; age range= 18-33 years) were selected by the recall and voluntary method. The Stroop cognitive assignments, point scanning, n-back and misinformation paradigm, as well as the Depression Anxiety Stress Scale (DASS-21) and the Positive and Negative Affect Schedule (PANAS), were used to collect the data. Data were analyzed using SPSS-24 through one-way and two-way Kruskal-Wallis and U-Mann-Whitney methods. Results: Negative emotional load of the task caused the highest amount of false memory (p=0.001) and the positive emotional load and the lack of emotional load caused the lowest amount of false memory (p=0.001). The type of mood induction did not affect the amount of false memory (p=0.578). The highest false memory was created in association with negative mood induction and negative emotional load of the task and the lowest false memory was created in association with positive mood induction and the task without emotional load (p=0.019). Conclusion: This study shows that the effect of the emotional load of the task on creating false memory is greater than mood induction. It is suggested that in future research, the effects of the emotional load of the task and mood induction on false memory (in two stages of decoding and retrieval) at different arousal levels should be investigated. In addition, the findings of this study should be reviewed to determine the applicability in judicial and clinical settings as well.

Limit load space of rigid strip footing on cohesive-frictional soil subjected to eccentrically inclined loads

In geotechnical engineering, the stability of strip footings under eccentrically inclined coupled loads is a major concern. The objective of this paper was to estimate the ultimate bearing capacity of a rigid strip footing, subjected to eccentrically inclined loads resting on cohesive-frictional soil, using the rigid plastic finite element method (RPFEM). In the numerical analysis, an interface element was introduced to properly evaluate the interaction between the footing base and the soil. The footing base was assumed to be rigid and rough, as it most often is in reality. Focus was placed on the effect of the soil properties (cohesive strength c, internal friction angle ϕ, and unit self-weight γ) and footing width B on the loading planes of the V-H-M limit load space (vertical load-horizontal load-moment) in order to consider the uniqueness of this limit load space. In particular, the effect of the two directions of the horizontal load, namely, positive and negative horizontal loads, on the V-H-M limit load space was clarified. The numerical results of the RPFEM showed that the negative horizontal load had a positive effect on supporting a higher bearing capacity than the positive horizontal load in the presence of a small eccentricity length. However, the results also showed a negligible effect on the bearing capacity for both directions of the horizontal load in the presence of a large eccentricity length. New equations were proposed to determine the V-H-M limit load space, predicted as functions of c/γB and ϕ, by taking into account the direction of the horizontal load. The applicability of the V-H-M limit load space was widely examined for several loading paths with different prescribed loads for V, H, and M. Consequently, the limit load space of the strip footing was clearly found to be unique for each value of c/γB and ϕ.

“Western” and “prudent” dietary patterns are associated with breast cancer among Mexican pre- and postmenopausal women

Breast cancer (BC) is the leading cancer worldwide among women. “Prudent” dietary patterns have been consistently and negatively associated with the risk of BC. However, prospective studies have shown a positive association between “Western” dietary patterns and the risk of BC, but only among postmenopausal women. In this regard, evidence from Latin America is scarce. Our aim was to assess the hypothesis that 2 dietary patterns (Western or prudent) were contrastingly associated with BC in pre- and postmenopausal women from Northern Mexico. We recruited 1045 BC incident cases and 1030 age matched (±5 years) population controls. Sociodemographic, reproductive, and dietary characteristics were obtained by direct interviews. We used a semiquantitative food frequency questionnaire to obtain information about diet 1 year before diagnosis for cases and 1 year before the interview for controls. Dietary patterns were identified through factor analysis. A Western-like pattern, which was mainly determined by positive loads in red and processed meats and foods rich in fats and sugars, was positively associated with BC both in pre- (odds ratio [OR] =23.47; 95% CI, 14.01-36.96) and in postmenopausal women (OR = 18.85; 95% CI, 13.74-25.87). In contrast, a prudent-like pattern, which was characterized by positive loads of vegetables, legumes, and corn, was negatively associated with pre- (OR = 0.35; 95% CI, 0.26-0.49) and postmenopausal BC (OR = 0.25; 95% CI, 0.19-0.32). Our results show the importance of dietary patterns in BC development regardless of menopausal status.

Nonlinear Modeling and Stability of a Doubly-Fed Variable Speed Pumped Storage Power Station with Surge Tank Considering Nonlinear Pump Turbine Characteristics

This paper investigates the nonlinear modeling and stability of a doubly-fed variable speed pumped storage power station (DFVSPSPS). Firstly, the mathematical model of DFVSPSPS with surge tank considering nonlinear pump turbine characteristics was derived and established. Then, Hopf bifurcation analysis of DFVSPSPS was performed. The stable region was identified and verified by example analysis. Moreover, the effect mechanism of nonlinear pump turbine characteristics on the stability of DFVSPSPS was explored. Finally, the influence of factors on the stability and dynamic response of DFVSPSPS was studied. The results indicate that the emerged Hopf bifurcation of DFVSPSPS is supercritical and the region on the low side of the bifurcation line is the stable region. Nonlinear head characteristics have a significant influence on the stability and dynamic response of DFVSPSPS. Nonlinear speed characteristics have an obvious effect on the stability and dynamic response of DFVSPSPS only under positive load disturbance and unstable surge tank. Nonlinear head characteristics are unfavorable for the stability of DFVSPSPS under positive load disturbance and favorable under negative load disturbance. A smaller flow inertia of penstock, a smaller head loss of penstock and a greater unit inertia time constant are favorable for the stability of DFVSPSPS. The stable region under the positive disturbance of active power is larger than that under the negative disturbance of active power. The time constant of the surge tank presents a saturation characteristic on the stability of DFVSPSPS.

Rituximab as induction therapy in pediatric kidney transplantation: A single-center experience in four patients.

The anti-CD20 rituximab is often used in the treatment of children with steroid-resistant nephrotic syndrome or EBV-induced post-transplant lymphoproliferative disorder. This single-center series reports the use of rituximab as induction therapy in pediatric kidney transplantation. Four children who received rituximab as induction therapy for kidney transplantation since 2016 were retrospectively analyzed. Clinical and laboratory data were extracted from medical records. The patients (2 boys and 2 girls) were aged from 6.1 to 11.9 years and were treated with rituximab on the day of the transplantation procedure; all the transplants came from deceased donors. In all patients, rituximab was used because of positive EBV viral loads before kidney transplantation. Viral loads remained undetectable for the first 6 months after the transplantation procedure and remained below the 4.5 log threshold thereafter. After a median follow-up of 2.3 years, none of the patients displayed rejection or de novo donor-specific antibodies; the glomerular filtration rate remained above 70 ml/min/1.73 m2 . No post-transplant lymphoproliferative disorder was observed. The results suggest that rituximab can be used as induction therapy to prevent EBV replication and its complications in case of positive viral load prior to kidney transplantation.

AN ARTIFICIAL INTELLIGENCE-BASED SOLUTION FOR THE CLASSIFICATION OF OAK DECLINE POTENTIAL

Abstract. Oak decline is a complex phenomenon. The classification of oak decline potential could be a valuable tool for forest management. This paper identified seven factors that influence oak decline: height, slope, aspect, temperature, perception, soil type, and aerosol. Then, factor analysis is used to determine factors that should be included in oak decline potential classification and reduce data complexity.As a result, five components explaining 92.49% of total variance are selected. The first component explains 40.34% of the variance, and three factors, including perception with positive and temperature and aerosol with negative load, have contributed to its construction. The second component is composed of a positive load of aspect, and soil type explains 14.89% of the variance. By explaining 14.10% of the variance, the third component consists of soil type and aspect with positive and negative loads, respectively. Slop and height have a positive load in constructing the fourth and fifth components.Five extracted components are used as input sets of PNN, MLC and SVM methods. 80% of samples are used for training methods, and 20% are used for testing purposes. Results are compared based on the overall accuracy of the methods.These components are used as an input set of three classification methods, including Probabilistic Neural Network (PNN), Maximum Likelihood Classification (MLC) and a Support Vector Machine (SVM). Based on the results, the SVM, with an overall accuracy of 0.87%, has proved its capability in oak decline potential classification.

Quantitative real-time PCR for the analysis of viral load among Hepatitis C Virus positive patients attending the medical Out Patient Department at a north Indian tertiary care centre

The present study aimed towards the determination of seroprevalence and viral load among hepatitis C virus (HCV) patients attending the Medicine Out Patient Department (OPD) of Government Medical College (GMC), Jammu over a period of two years and five months i.e. from May 2016 to September 2018. About 16315 patients were screened for anti-HCV antibodies using third-generation ELISA, among which 142 were reported to be positive amounting to seropositivity of 0.8%. Viral RNA was extracted and quantified from the positive samples and viral load analysis was done. The viral RNA was detected in 37 patients stating an active infection in 26% of positive patients. Among the 37 HCV RNA positive patients, the average age was reported to be 44 years with male preponderance (2.4:1). 23 patients were categorised under high viral load while 14 under low viral load. The major cause of HCV transmission appeared to be surgery and intravenous drug use (IVDU).

Pharmacist-led drug therapy management for hepatitis C at a federally qualified health care center

BackgroundChronic hepatitis C (HCV) infection is challenging to address in patients with barriers to accessing care, including those from underserved populations. Linking at-risk patients through the HCV cascade of care can address such disparities by leveraging existing patient–provider relationships to identify and treat HCV. Pharmacists are ideal clinical team members to provide direct-acting antiviral (DAA) management, given their expertise in pharmacotherapy and medication access. However, literature describing pharmacist-led DAA management at federally qualified health centers (FQHCs) is limited. Objective(s)To describe HCV screening, DAA prescribing and treatment initiation, post-treatment sustained virologic response (SVR) assessment, and treatment outcomes in an FQHC with pharmacist-led DAA management. MethodsThis study describes HCV screening rates in adults with select HCV risk factors receiving primary care at a Midwest FQHC over a 4-year period. In patients with a detectible HCV viral load, DAA prescription orders for patients referred to pharmacist-led DAA management was evaluated in comparison with usual care. Treatment completion and SVR results were assessed in patients referred to pharmacists. ResultsHCV screening in patients with identifiable risk factors increased from 8.0% to 67.5% over 4 years, driven by a clinical reminder for HCV screening in the birth year cohort. Of patients with positive HCV viral load results, 9.9% in the usual care group received an order for DAA therapy versus 57.1% (P < 0.001) in the pharmacist-led DAA management group. Of 162 patients referred to pharmacist-led DAA management, 61 (37.7%) initiated therapy. Of patients who initiated treatment, 57 (94.7%) had post-treatment viral load testing, with 46 (80.7% of treated patients) having SVR results and 45 (97.8% of SVR tested patients) testing negative. No usual care patients had subsequent negative HCV viral load results. ConclusionPharmacist-led DAA management is an effective intervention to improve the treatment of patients with HCV in the FQHC setting.

Implications of ΔK‐Rratio in vacuum

AbstractIn this article we discuss the high vacuum implications on the role of positive load ratios (R = Pmin/Pmax) on the threshold ΔKthand fatigue crack growth (FCG) behavior in commercial alloys. It is experimentally observed that the ΔKthis independent ofRin vacuum. Also, for a given applied ΔK, FCG rate is weakly dependent ofRover the entire range of crack growth rates for several alloys. In addition, limited data on both short and long crack FCG in vacuum results fall within the same experimental scatter suggesting that a typical small crack FCG effect observed in lab air was insignificant or diminished in vacuum. A marginalR‐ratio effects on ΔKthin vacuum are seen for materials with different microstructures, yield strengths, elastic modulus, work hardening properties, and slip modes. The provided analysis and examples seem to imply that FCG in vacuum be primarily dependent on applied ΔK that comes from mechanical driving force. Possible mechanistic explanations are given.

The Diagnostic Dilemma of a Nodule Appearing as a Mass

<h3>Introduction</h3> Posttransplant lymphoproliferative disorder (PTLD) after lung transplantation (LT) occurs due to immunosuppressant therapy that limits antiviral host immunity and permits Epstein-Barr viral (EBV) replication and transformation of B cells. <h3>Case Report</h3> We present the case of a 61-year-old man with history of bone marrow transplant (08/2009) for non-Hodgkin's lymphoma and bilateral LT (04/2021) for idiopathic pulmonary fibrosis - EBV status: D+/R+. The transplant was complicated by prolonged duration of ECMO and a lengthy post-LT hospital stay for renal failure, significant deconditioning, and acute on chronic respiratory failure requiring tracheostomy and fiberoptic bronchoscopic airway stent placement to limit atelectasis. He also required a muscle flap for right bronchial anastomotic dehiscence in this time course. After 4 months, he was finally discharged to home with tracheostomy in place, requiring oxygen supplementation based only on physical demands. On his return to clinic, an inspection bronchoscopy was performed to assess the airway stent, which was found to have purulent secretions concerning for infection. Bronchoalveolar lavage was positive for pan-sensitive <i>Pseudomonas</i> requiring intravenous antibiotic therapy. At the same time, a chest CT revealed multiple pulmonary nodules in the right lung base, the largest measuring 2.8 cm in diameter. A CT-guided biopsy confirmed EBV-positive polymorphic PTLD. Immunostaining yielded positive results for CD20, CD138, CD79a, MUM1, and EBV-encoded RNAs (EBER) (<b>Figure 1</b>). Notably, this patient never had a positive EBV-viral load. Given his undetectable EBV levels, a decision was made to reduce immunosuppression and follow imaging and blood counts as appropriate. <h3>Summary</h3> EBV-positive PTLD with negative EBV viremia is an unusual combination in an EBV-seropositive recipient with donor non-mismatch. The patient's tenuous respiratory status requiring intensive corticotherapy likely contributed significant risk for PTLD in this case.

Hepatitis B vertical transfer and its risk factors in pregnant women in the eastern part of Iran

One of the main causes of chronic hepatitis is mother to child transfer which is also known as vertical transfer (VT). Although there are several studies regarding the VT mechanism and its risk factors, none of these studies succeeded in explaining this process, completely. We conducted this study aiming at investigating VT mechanism and risk factors in this region. The present study was a descriptive-analytic cross-sectional study on HBS Ag positive pregnant women, which was conducted from March 2018 to March 2020 in Amir-Al-Momenin Hospital in Zabol, Sistan-and-Baluchestan province, Iran. In this study all samples were tested for HBV markers (HBsAg, anti-HBs, HBeAg, anti-HBe, anti-HBc, and HBV-DNA) and anti-HCV by enzyme-linked im­munosorbent assay (ELISA). All statistical analyzes were performed using SPSS version 22 software. Totally 43 infants of HBS antigen positive mothers were investigated. HBe antibody and HBe antigen were found in 25 (62.5%) and 2 (5%) of mothers, respectively. There was no significant difference between the newborns with and without hepatitis B infection regarding maternal age (p=0.216), duration of the infection in mother (p=0.892), AST (0.779), AL (0.449) and ALP (0.065). Mothers with positive viral load during pregnancy delivered newborns with positive HBS antigen much more than mothers with negative HBS antigen. However, this difference was not statistically significant (p=0.642). Although positive viral load was more common in neonates delivered from positive viral load mothers, the observed difference was also remained non-significant (p=0.978). Our study provided evidences regarding that demo­graphic, immunologic and clinical characteristics of mothers with hepatitis B infection did not play considerable role in the vertical transmission of the infection to the newborns as well as the severity of the following infection. We also sug­gested the possibility of placenta acting as a source of infection in VT. Further longitudinal studies with larger sample sizes are needed to show the exact predictors of transmission of the infection from infected mothers to their children.

Wind Loads on Solar Panels Mounted on Facade of High-Rise Residential Building

Wind effects on solar panels mounted on façade of high-rise residential building are studied through wind tunnel test. The model with scale ratio of 1:80 is adopted. Results show that the top floor panel is dominated by the upward negative wind load, and the panel at the mid height floor suffers the downward positive wind load, when the panels are mounted on the windward face. The influence of different inclination angles on force coefficient of the panel is also studied. It is found that positive peak force coefficient increases with the increase of panel’s inclination angle, most unfavorable extreme wind suction decreases with increase of panel’s inclination angle. Results show that the location of panels has significant effect on the design wind load. The peak force coefficient values of [Formula: see text] and [Formula: see text] can be used as the recommended values for design wind coefficients of the top floor panels. Peak force coefficient values of [Formula: see text] and [Formula: see text] can be used as the recommended values for design wind coefficients of the mid floor panels. The correlations between wind loads on different panels are also examined to check the flow mechanism around the panel. Different trends can be clearly checked from the results for different incident wind directions, suggesting the complex flow condition near panels. The greater the panel inclination is, the higher the correlation of net force coefficient between two adjacent panels is.

Design and modeling of hardware-in-loop test bench for hydraulic excavator based on dynamic load emulation

Hardware-In-Loop (HIL) testing is an effective means to improve the development process of construction machinery. This paper presents a HIL test bench for hydraulic excavator based on dynamic load emulation. The critical technology of HIL test bench is the ability to emulate realistic load. Therefore, a digging load emulating model is established and implemented in real-time environment. To improve the load emulating accuracy, the soil-bucket interaction model is calibrated based on the coupling of the discrete element method (DEM) and multibody dynamics (MBD). The experimental scheme under positive and negative load working conditions is designed to correct the testing error. The performance of the HIL test bench is evaluated from multiple perspectives of load emulating accuracy, system power flow and fuel consumption. Compared with actual excavation tests, the testing error of the proposed HIL test bench is no more than 12%.

Secondary Immunosuppression in Pediatric Kidney Transplant Recipients.

Currentimmunosuppressive treatments for kidney transplant recipients have improved graft viability at the expense of impaired immune surveillance. The tools for monitoring immune status in pediatric kidney transplant recipients have not been widely investigated. Better knowledge could help recognize over immunosuppression and allow implementation of individualized preventive strategies. This retrospective and observational study included 28 pediatric kidney transplant recipients treated at a tertiary hospital. We measured peripheral blood lymphocyte subpopulations, immunoglobulins, immunosuppressivedrug levels, and viral loads. Reference analytical values for different age ranges were used to determine immune status. We recorded overall hospitalizations due to opportunistic infections and positive viral loads posttransplant. We found hypogammaglobulinemia and lymphopenia in 19% and 41% of the patients, respectively. Peripheral blood lymphocyte subpopulations were below normal limits in one-third of the sample. These parameters were not related to the current number or plasma levels of immunosuppressive drugs. During follow-up, cytomegalovirus, Epstein-Barr virus, and BK virus viremias were detected in 60.7% of the patients. Admissions due to opportunistic infections happened in 57.1%, mainly related to severe viral disease (30%) or gastrointestinal infections (26.7%). Most occurred in younger transplant recipients and during the first 2 years posttransplant (73.3%). We found no significant relation between peripheral blood lymphocyte subpopulations and hospital admissions for opportunistic infections or positive viral loads during follow-up. Recurrent hospitalizations for opportunistic infections and analytical disorders in the immune system suggested that secondary immunosuppression in pediatric kidney transplant recipients was frequent. Immunosuppression was not directly related to plasma drug levels or the number of immunosuppressive drugs. Thus, immune monitoring might be helpful in combination with immunosuppressant levels to assess immunosuppression status and to establish individualized preventive measures.

Integration of Renewable Based Distributed Generation for Distribution Network Expansion Planning

Electrical energy is critical to a country’s socioeconomic progress. Distribution system expansion planning addresses the services that must be installed for the distribution networks to meet the expected load need, while also meeting different operational and technical limitations. The incorporation of distributed generation sources (DGs) alters the operating characteristics of modern power systems, resulting in major economic and technical benefits, such as simplified distribution network expansion planning, lower power losses, and improved voltage profile. Thus, in this study, an analytical method is used to design the expansion planning of the Addis North distribution network considering the integration of optimal sizes of distributed generations for the projected demand growths. To evaluate the capability of the existing Addis North distribution network and its capability to supply reliable power considering future expansion, the load demand forecast for the years 2020–2030 is done using the least square method. The performance evaluation of the existing and the upgraded network considering the existing and forecasted load demand for the years 2030 is done using ETAP software. Accordingly, the results revealed that the existing networks cannot meet the existing load demand of the town, with major problems of increased power loss and a reduced voltage profile. To mitigate this problem, the Addis North feeder-1 distribution network is upgraded and for each study case, the balanced and positive sequence load flow analysis was executed and the maximum total real and reactive power losses were found at bus 29. The result shows that the upgraded network of bus 29 was the optimal location of DG and its size was 9.93 MW. After the optimal size of DG was placed at this bus, the real and reactive power losses of the upgraded networks were 0.2939 MW and 0.219 MVAr, respectively. At bus 29 the maximum power losses reduction and voltage profile improvements were found. The active and reactive power losses were minimized by 21.285% and 19.633% respectively and the voltage profiles were improved by 8.78%. Thus, in the predicted year 2030, DG power sources could cover 61.12% of the feeder-1 power requirements.

Investigations on fatigue properties of red sandstone under positive and negative pure bending loads

Brittle materials such as rock and concrete may be subjected to positive and negative cyclic loading effects such as earthquakes and construction disturbances, and bending damage is one of the most likely forms of damage. A four-point bending fixture was designed to conduct fatigue tests with positive and negative stress ratios under pure bending to investigate the influence of cyclic loading on the form and mechanism of damage. The fracture energy calculation equation based on crack mouth opening displacement (CMOD) was derived, and the fracture criterion based on fracture toughness and fracture energy was established, which was in good agreement with the experimental results. Under the pure bending fatigue load, the hysteresis loop of the P-CMOD curve shows a loose-dense-loose law, and the damage curve can be divided into three stages of initial, stable, and accelerated law. Stress level and stress ratio are two main factors affecting fatigue life. The fatigue life of negative stress ratios is greater than that of positive stress ratios because there is a crack closure process in negative stress ratios, which affects the fatigue life. The final damage occurs for positive stress ratio specimens when the fatigue dissipation energy is greater than the static fracture energy. Static CMOD starting and final values were introduced to define the fatigue damage variables, and a damage evolution model was established better to simulate the evolution with positive and negative stress ratios.

Stability of cruciform specimens for fracture tests under compression

Cruciform specimens have been developed in the last decades in order to evaluate the fatigue and fracture material behaviour under biaxial stress fields. These evaluations have been generally conducted under positive load ratios, so as to prevent the potential buckling of these generally thin specimens.This paper reports a numerical investigation on the stability of two cruciform specimens in order to provide useful information for the design of biaxial fracture tests under both tension and compression. Two cruciform geometries were selected among those widely accepted in literature and slightly modified so as to apply equal boundary conditions. FEM simulations were performed under tensile and compressive loading conditions by considering geometric imperfections based on the superposition of the buckling modes. Results were cross-compared in terms of stress fields, load–displacement curves, stress intensity factors and critical loads along crack propagation. Guidelines of general validity were derived.

Analysis on influencing factors of HBV intrauterine transmission based on integration of decision tree model and logistic regression model

Objective: To investigate the influencing factors of HBV intrauterine transmission and their interaction effects by integrating logistic regression model and Chi-squared automatic interaction detector (CHAID) decision tree model. Methods: A total of 689 pairs of HBsAg-positive mothers and their neonates in the obstetrics department of the Third People's Hospital of Taiyuan from 2007 to 2013 were enrolled, and the basic information of mothers and their neonates were obtained by questionnaire survey and medical record review, such as the general demographic characteristics, gestational week and delivery mode. HBV DNA and HBV serological markers of the mothers and newborns were detected by fluorescence quantitative PCR and electrochemiluminescence immunoassay respectively. The CHAID decision tree model and unconditional logistic regression analysis were used to explore the factors influencing HBV intrauterine transmission in neonates of HBsAg-positive mothers. Results: Among the 689 neonates, the incidence of HBV intrauterine transmission was 11.47% (79/689). After adjusted for confounding factors, the first and second logistic multivariate analysis showed that cesarean delivery was a protective factor for HBV intrauterine transmission (OR=0.25, 95%CI: 0.14-0.43; OR=0.27, 95%CI: 0.15-0.46); both models indicated that maternal HBeAg positivity and HBV DNA load ≥2×105 IU/ml before delivery were risk factors of HBV intrauterine transmission (OR=3.89, 95%CI: 2.32-6.51; OR=3.48, 95%CI: 2.12-5.71), respectively. The CHAID decision tree model screened three significant factors influencing HBV intrauterine transmission, the most significant one was maternal HBeAg status, followed by delivery mode and maternal HBV DNA load. There were interactions between maternal HBeAg status and delivery modes, as well as delivery mode and maternal HBV DNA load before delivery. The rate of HBV intrauterine transmission in newborns of HBeAg-positive mothers by vaginal delivery increased from 19.08% to 29.37%; among HBeAg-positive mothers with HBV DNA ≥2×105 IU/ml, the rate of HBV intrauterine transmission increased to 33.33% in the newborns by vaginal delivery. Conclusions: Maternal HBeAg positivity,maternal HBV DNA ≥2×105 IU/ml and vaginal delivery could be risk factors for HBV intrauterine transmission in newborns. Interaction effects were found between maternal HBeAg positivity and vaginal delivery, as well as vaginal delivery and high maternal HBV DNA load. Logistic regression model and the CHAID decision tree model can be used in conjunction to identify the high-risk populations and develop preventive strategies accurately.