Seismic Performance Assessment of Deteriorated Two-Span Reinforced Concrete Bridges

This paper presents a nonlinear analysis procedure for the seismic performance assessment of deteriorated reinforced concrete bridges using a modified damage index. A finite-element analysis program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), is used to analyze deteriorated two-span simply supported reinforced concrete bridges. The new nonlinear material models for deteriorated reinforced concrete behaviors were proposed, considering corrosion effects as shown in a reduction in reinforcement section and bond strength. A modified damage index aims to quantify the seismic performance level in deteriorated reinforced concrete bridges. Several parameters of two-span simply supported deteriorated reinforced concrete bridge have been studied to determine the seismic performance levels. The newly developed analytical method for assessing the seismic performance of deteriorated reinforced concrete bridges is verified by comparison with the experimental and analytical parameter results.

Childhood Systemic Lupus Erythematosus: Presentation, management and long-term outcomes in an Australian cohort

Objectives Systemic Lupus Erythematosus (SLE) is a serious autoimmune disease often resulting in major end-organ damage and increased mortality. Currently, no data exists focussing on the presentation, long-term management and progression of SLE in the Australian paediatric population. We conducted the first Australian longitudinal review of childhood SLE, focussing on response to treatment and outcomes. Methods Detailed clinical and laboratory data of 42 children diagnosed with SLE before 16 years from 1998 to 2018 resident in Western Australia was collected. Data was collected at diagnosis and key clinical review time points and compared using the Systemic Lupus Collaborating Clinics (SLICC) and Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) criteria. End organ damage was assessed against Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI). Incidence rates of disease complications and end organ damage were determined. Results Of the 42 children, 88% were female with average age at diagnosis of 12.5 years. Indigenous Australians were over represented with an incidence rate 18-fold higher than non-Indigenous, although most children were Caucasian, reflecting the demographics of the Australian population. Median duration of follow-up was 4.25 years. On final review, 28.6% had developed cumulative organ damage as described by the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (incidence rate: 0.08/PY (95% CI 0.04–0.14)), and one child died. Twenty-nine children had renal involvement (incidence rate: 0.38/PY (95% CI 0.26–0.56)). Of the 27 patients with biopsy proven lupus nephritis, 70% had Class III or IV disease. Average length of prednisolone use from diagnosis was 32.5 months. Hydroxychloroquine ( n = 36) and mycophenolate mofetil ( n =21) were the most widely used steroid sparing agents. 61.9% received rituximab and/or cyclophosphamide. Conclusion This is the first longitudinal retrospective review of Australian children with SLE, with a markedly higher incidence in Indigenous children. Although improving, rates of end organ complications remain high, similar to international cohort outcomes. Longitudinal multi-centre research is crucial to elucidate risk factors for poor outcomes, and identifying those warranting early more aggressive therapy.

Predictors of admission to intensive care unit among systemic lupus erythematosus patients: prospective study

Background Through the disease course, different prognostic factors have been addressed in patients with SLE admitted to intensive care unit. For instance, higher disease activity on admission, recent immunosuppressive therapy, infections, renal disease, and central nervous system involvement, all had negative effects on the outcome of the disease. It is still a clinical challenge for the physicians to manage this disease which has many aspects regarding its pathogenesis, clinical presentation, and its outcome remains to be explained. The aim of our study was determining the course, outcome, and determinants of admission to intensive care unit in patients with systemic lupus erythematosus. Results Patients with systemic lupus erythematosus admitted to the intensive care unit in the study sample was 21.4%, and the death rate among them is 18.2%. In our study, the main causes of intensive care admission were cardiovascular causes followed by renal failure then infections. Holding the other covariates constant, a higher value of CRP, SLEDAI, and damage index value is associated with intensive care admission among lupus patients. Conclusion Our study showed that systemic lupus erythematosus patients with a higher value of CRP, SLEDAI, and damage index value were liable for intensive care unit admission. Good control of disease activity of SLE which in turn reduces damage of different body systems is mandatory. Periodic screening for functions of renal and cardiac systems is of great value. Proper screening and prophylaxis is recommended against variable causes of infections. Rheumatologists should be careful in controlling SLE active disease and to balance the doses of immunosuppressive especially in the presence of infection. They should focus the research on finding more accurate infection predictive index parameters to early predict the onset of infection.

Diagnosis of internal cracks in concrete using vibro-acoustic modulation and machine learning

This paper investigates the utility of physics-informed machine learning models for vibro-acoustic modulation (VAM)–based damage localization in concrete structures. Vibro-acoustic modulation is a nonlinear dynamics-based non-destructive testing method, which was initially developed to perform damage detection and later extended to accomplish damage localization. The VAM-based damage (hidden crack) diagnosis is performed by analyzing the damage index pattern on the surface of the component to arrive at the size and location of the hidden damage. Past investigations have employed heuristically selected damage index thresholds as well as computationally expensive Bayesian estimation methods for VAM-based damage localization in two (surface) dimensions. Compared to these studies, the proposed methodology automates the threshold selection (algorithmic instead of heuristic), increases the speed of the probabilistic damage diagnosis process, and enables the estimation of damage depth. We generate training data (damage index) for the machine learning models using the pertinent nonlinear dynamics (finite element) models using different combinations of test parameters. The (supervised) machine learning models are thus informed by computational physics models. These include two types of artificial neural network (ANN) models: classification models that identify whether a sensor location is damaged or not and regression models that enable Bayesian estimation to obtain the posterior probability distribution of damage location and size. The accuracy of machine learning-based diagnosis is evaluated using both numerical and laboratory experiments. The proposed physics-informed machine learning models for VAM-based damage diagnosis are able to achieve an accuracy of about 60–64% in the validation experiments, indicating the potential of these methods for internal crack detection. The results show that for complex (nonlinear dynamics-driven) diagnostic methods, damage index patterns learned from physics models could be successfully used for damage detection as well as localization.

Metabolic syndrome predicts new damage in systemic lupus erythematosus patients: Data from the Almenara Lupus Cohort

Objectives This study aims to determine whether the MetS predicts damage accrual in SLE patients. Methods This longitudinal study was conducted in a cohort of consecutive SLE patients seen since 2012 at one single Peruvian institution. Patients had a baseline visit and then follow-up visits every 6 months. Patients with ≥ 2 visits were included. Evaluations included interview, medical records review, physical examination, and laboratory tests. Damage accrual was ascertained with the SLICC/ACR damage index (SDI) and disease activity with the SLEDAI-2K. Univariable and multivariable Cox-regression survival models were carried out to determine the risk of developing new damage. The multivariable model was adjusted for age at diagnosis; disease duration; socioeconomic status; SLEDAI; baseline SDI; the Charlson Comorbidity Index; daily dose; and time of exposure of prednisone (PDN), antimalarials, and immunosuppressive drugs. Results Two hundred and forty-nine patients were evaluated; 232 of them were women (93.2%). Their mean (SD) age at diagnosis was 35.8 (13.1) years; nearly all patients were Mestizo. Disease duration was 7.4 (6.6) years. The SLEDAI-2K was 5.2 (4.3) and the SDI, 0.9 (1.3). One hundred and eight patients (43.4%) had MetS at baseline. During follow-up, 116 (46.6%) patients accrued at least one new point in the SDI damage index. In multivariable analyses, the presence of MetS was a predictor of the development of new damage (HR: 1.54 (1.05–2.26); p < 0.029). Conclusions The presence of MetS predicts the development of new damage in SLE patients, despite other well-known risk factors for such occurrence.

Damage detection in bridges under moving loads based on subspace projection residuals

This paper proposes a data-driven method using subspace projection residual of the responses to identify the damage locations in bridges subjected to moving loads. In this method, a moving window with a certain length determined by the sampling frequency and the fundamental frequency of the measured responses is used to cut out the acceleration responses of the bridge subjected to a moving vehicle. The characteristic subspaces of the windowed signals are subsequently extracted to calculate the local damage index using the subspace projection residual. When the window moves to the damage location, the orthogonality between the active subspace of the damaged state and the null subspace of the healthy state is invalid, which leads to a relatively large projection residual that can be used to localize the damage. To improve the reliability of the proposed approach, a one-side upper confidence limit is introduced. A simply supported beam bridge subjected to a moving mass is simulated to verify the effectiveness of the proposed method. Numerical results indicate that the proposed approach can accurately localize the single and multiple damages, even when the responses are smeared with a significant noise. Experimental tests conducted on a steel beam bridge model also demonstrate the performance and accuracy of the proposed approach. The results demonstrate that the proposed method can localize the damage even with a small number of sensors, indicating the method has a good and promising performance for practical engineering applications.

Implication of plasma gelsolin in systemic lupus erythematosus patients

Background Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder with more than one organ involvement. Kidney is the foremost commonly affected one. Gelsolin is a protein that induces depolymerization of actin filaments thus preventing downstream stimulation of inflammatory reactions. The aim of this work was to detect the relation of plasma gelsolin to SLE disease activity and severity indices in order to find out if plasma gelsolin could be used as a biomarker of the disease. This study was conducted on 50 SLE female patients and 30 matched control. SLE disease activity Index (SLEDAI) and SLE damage index (SDI) were assessed. All lupus nephritis (LN) patients were subjected to an ultrasound-guided kidney biopsy. Plasma gelsolin level was measured. Results The mean age of the patients was 38.5 ± 6.3 years (26–51 years) with median disease duration of 5 (3–9.3) years. Eighteen patients had LN, 11 had cardiac manifestations and 12 had chest manifestations. The mean SLEDAI was 13.1 ± 4.5 (4–22) and the median SDI was 2 (1–3). Plasma gelsolin level was significantly lower in SLE patients (74.9 mg/l; 57.5–98.8 mg/l) compared to control (801.5 mg/l; 225–1008.3 mg/l) (p < 0.001). There were significant negative correlations of gelsolin levels with anti-ds DNA (r = − 0.63, p < 0.001), SLEDAI (r = − 0.79, p < 0.001), and SDI (r = − 0.74, p = 0.001). Plasma gelsolin level was significantly lower in SLE patients with high/very high activity grades compared to those with low and moderate (p = 0.007 and p < 0.001 respectively). A gelsolin level of ≤ 78.95 mg/l significantly predicted renal affection (p < 0.001), with a sensitivity of 100%, specificity 71.9%, and a positive predictive value 66.7%. Conclusion A decreased gelsolin level is associated with disease activity in SLE patients. Plasma gelsolin was well related to disease activity and severity with a high predictive value for renal affection comparable to anti-ds DNA titre. Plasma gelsolin is a potentially important predictive biomarker for SLE and LN.

Damage detection based on output-only measurements using cepstrum analysis and a baseline-free frequency response function curvature method

Low-severity multiple damage detection relies on sensing minute deviations in the vibrational or dynamical characteristics of the structure. The problem becomes complicated when the reference vibrational profile of the healthy structure and corresponding input excitation, is unavailable as frequently experienced in real-life scenarios. Detection methods that require neither undamaged vibrational profile (baseline-free) nor excitation information (output-only) constitute state-of-art in structural health monitoring. Unfortunately, their efficacy is ultimately limited by non-ideal input excitation masking crucial attributes of system response such as resonant frequency peaks beyond first (few) natural frequency(ies) which can better resolve the issue of multiple damage detection. This study presents an improved frequency response function curvature method which is both baseline-free and output-only. It employs the cepstrum technique to eliminate [Formula: see text] decay of higher resonance peaks caused by the temporal spread of real impulse excitation. Long-pass liftering screens out the bulk of low-frequency sensor noise along with the excitation. With more visible resonant peaks, the cepstrum purified frequency response functions (regenerated frequency response functions) register finer deviation from an estimated baseline frequency response function and yield an accurate damage index profile. The simulation and experimental results on the beam show that the proposed method can successfully locate multiple damages of severity as low as 5%.

Reduced expression of hematopoietic progenitor kinase 1 in T follicular helper cells causes autoimmunity of systemic lupus erythematosus

Backgroud T follicular helper (Tfh) cells have been discovered to be the main CD4+ T cells assisting B cells to produce antibody. They are over activated in patients with systemic lupus erythematosus (SLE) and consequently lead to excessive immunity. Hematopoietic progenitor kinase 1 (HPK1) negatively regulates T cell-mediated immune responses and TCR signal. This study aimed to investigate the roles of HPK1 in SLE Tfh cells. Methods HPK1 mRNA and protein levels in Tfh cells were measured by real-time quantitative PCR and western blot analysis, respectively. The production of IL-21, B cell−activating factor (BAFF), interferon γ (IFNγ), IL-17A, IgM, IgG1, IgG2, and IgG3 were analyzed using enzyme linked immunosorbent assay. Tfh cells proliferation was evaluated with 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results HPK1 mRNA and protein levels were significantly reduced in SLE Tfh cells, and negatively correlated with SLE disease activity index (SLEDAI) and Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) Damage Index for SLE (SDI). Knocking down HPK1 with siRNA in normal Tfh cells greatly elevated Tfh cells proliferation and secretions of IL-21, BAFF, IFNγ, IgG1, IgG2, and IgG3. There were no marked alterations in IL-17A and IgM productions. The opposite effects were observed in SLE Tfh cells transfected with HPK1 overexpressing plasmid: Tfh cells proliferation and productions of IL-21, BAFF, IFNγ, IgG1, IgG2, and IgG3 were all alleviated. And there were no significant changes in IL-17A and IgM levels. Conclusion Our results suggest for the first time that inhibited expression of HPK1 in SLE Tfh cells leading to Tfh cells overactivation and B cells overstimulation, subsequently, the onset and progression of SLE.