Peritoneal Dialysis Associated Peritonitis Rate – Validation of a Simplified Formula

Peritonitis is the most important therapy-related complication of peritoneal dialysis (PD). Unfortunately, many PD centers around the world do not accurately record peritonitis rate, mainly because they cannot ascertain PD patient time-at-risk from “patient flow” data - that is, calculating PD patient-days from dates when patients start and finish PD. We propose a simplified method of calculating PD peritonitis rate using PD patient time-at-risk from “patient stock” data - - that is, calculating PD patient-days from the number of prevalent PD patients at the center at the start of the year and the corresponding number at the end. We compared gold-standard measurements of annual PD peritonitis rates with simplified ones in the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) / New Zealand (NZ) PD Registry, and Le Registre de Dialyse Péritonéale de Langue Française et hémodialyse à domicile (the RDPLF). A total of 268 centers from 9 countries with 4311 center-years and 110,185 patient-years of follow-up were modelled. Overall agreement was excellent with a concordance correlation coefficient of 0.978 (95% confidence interval [CI] 0.975-0.980) in ANZDATA / NZ PD Registry, and 0.978 (0.977-0.980) in the RDPLF. There was statistically significant lower agreement for smaller centers in the registries at 0.972 (0.966-0.976) and 0.973 (0.970-0.976) respectively, although the performance of the simplified formula remains clinically sound in even these centers. The simplified method of calculating PD peritonitis rate is accurate, and will allow more centers around the world to measure, report, and work on reducing PD peritonitis rates.

Numerical Investigation of Residual Displacement of Rocking Self-Centering Columns Under Cyclic Loading

Well-designed rocking self-centering (RSC) columns are capable of achieving small residual displacement. However, few studies conducted the quantitative analysis for the residual displacement of RSC columns. The residual displacement is the product of the struggle between the self-centering (SC) capacity and the energy dissipation (ED) capacity. In this study, a SC factor and an ED parameter were defined to reflect the SC and ED capacity of the RSC column, respectively. The influence of eight common design parameters on the SC factor and the ED parameter was explored using factorial analysis. Parametric analysis was performed to investigate the tendency of the SC factor and the ED parameter with the increase of maximum drift. According to the results of the parametric analysis, the effect of the SC factor and the ED parameter on the distribution of the residual drift was researched statistically. A simplified formula was proposed to calculate the upper limit of the residual drift. What is more, a set of predictive regression formulas was established to estimate the actual residual drift, these regression formulas have an applicable condition that the ED parameter should be larger than 0.75. When the ED parameter was less than 0.75, the residual drift is approximate to zero.

Analysis of the Shear Capacity of Ultrahigh Performance Concrete Beams Based on the Modified Compression Field Theory

An analysis model of the shear capacity of prestressed ultrahigh performance concrete (UHPC) beams under the combined action of bending and shearing was established in this paper based on the modified compression field theory and by considering the unique material constitutive relation of UHPC. Shear tests were performed using three prestressed UHPC-T beams with different shear-span ratios to verify the correctness of the model. The results showed that the shear-span ratio greatly influenced the shear capacity and failure modes of UHPC-T beams. Upon increasing the shear-span ratio, the failure modes of the three beams were inclined compression failure, shear compression failure, and diagonal tension failure, successively. When the shear-span ratio changed from 1.04 to 2.12, the shear bearing capacity decreased greatly; however, when the shear-span ratio changed from 2.12 to 3.19, the decrease of the shear bearing capacity was very small. In addition, the MCFT analysis model was used to analyze the experimental data, and the predicted results were in good agreement, which proved the applicability of the model. Finally, according to the existing shear test results of UHPC beams and based on the main influencing factors, a simplified formula for predicting the shear capacity of UHPC beams was obtained by fitting. Comparing the MCFT model with the results of other pieces of literature, this formula accurately predicted the shear capacity of UHPC beams. The MCFT model and the simplified formula presented in this paper provide a powerful tool for predicting the shear performance of UHPC-T beams, which will contribute to the design and analysis of UHPC-T beams.

A simplified formula for determination of relative pressure in the precision forging of spur gears

In this study, the relative forging pressures of spur gears were evaluated. The precision forging of spur gears was analyzed by using the upper bound method considering corner filling and bulging effect. Numerical and experimental studies were performed to investigate the effects of various parameters, such as the number of teeth, modules, facewidth, bore diameter, and friction factor on the relative forging pressure of spur gears. The results were compared with the previous studies and a simplified formula was suggested to predict the relative pressure of precision forging of spur gears. The predicted relative forging pressures obtained by the suggested formula are shown much closer to the experimental results for the complete filling of the die cavity.

POS0825 DEVELOPMENT OF A NEW AND SIMPLIFIED FORMULA TO PREDICT MORTALITY IN PATIENTS WITH ANCA-ASSOCIATED VASCULITIS ADMITTED TO THE INTENSIVE CARE UNIT

Background:ANCA-associated vasculitis (AAV) can present with a wide range of symptoms, including acute kidney injury (AKI) requiring renal replacement therapy or diffuse alveolar hemorrhage (1). These two manifestations often require admission to an intensive care unit (ICU) and are associated with increased mortality. To predict ICU mortality, the Simplified Acute Physiology Score version 2 (SAPS2) is often used but has not been formally tested in AAV patients (2). In addition, it is cumbersome to assess.Objectives:To develop a novel, simplified formula to predict ICU mortality in an AAV ICU population from an academic tertiary care center.Methods:We retrospectively recorded clinical and laboratory parameters in patients admitted to our ICU from 2000-2018. We performed risk factor analysis using univariate and multivariate logistic regression. In the multivariate case we applied the least absolute shrinkage and selection operator (lasso) method for variable selection. We considered average marginal effects and partial dependence plots in order to describe the influence of various independent variables on the probability of death more specifically. We evaluated our new score by comparing the corresponding area under the curve (AUC) to the AUC corresponding to the established SAPS2 score.Results:We analyzed 58 patients with AAV (39 granulomatosis with polyangiitis, 19 with microscopic polyangiitis) with a mean age of 74±14 (GPA) and 73±12 (MPA). 19/39 (48.7%) of GPA and 9/19 (47.4%) were female. Reasons for admission included disease manifestations or infectious complications from treatment (e. g. pneumonia, urinary tract infection). In total, 13/58 (22.4%) patients died throughout the study (10 GPA, 3 MPA patients). Using a cut-off threshold of 40 for SAPS2, sensitivity and specificity for mortality were 0.92 and 0.60, respectively. Confidence interval for the AUC was [0.68,0.95]. In the fitted multivariate logistic regression model, lasso was applied for variable selection. The identified variables included: disease duration, pH, procalcitonin, hemoglobin, leukocytes on admission, coronary heart disease, and pneumonia on admission. The estimated mortality is given by the formula ƒ(β0 + β1χ1 + …+ β7χ7), where ƒ(u)=1/(1+exp(−u)). Table 1 shows the estimated mortality for various values of the new score.Table 1.Example scores predicting mortality using the novel formula.ScorePredicted mortality-2.20.1-1.10.2500.51.10.752.20.9Testing if the AUC corresponding to the new model is significantly larger than the one corresponding to the SAPS2 score as independent variable resulted in p-value of 0.037. To identify possible overfitting, a 5-fold cross validation was performed. This resulted in a CI for the AUC of [0.64,0.96], suggesting that the new score allows for simpler prediction of mortality.Conclusion:We developed a novel formula corresponding to a score which is able to simpler predict mortality in patients with AAV admitted to the ICU. We will test our formula in the available ICU database MIMIC III, which comprises a large dataset of ICU patients.References:[1]Kitching AR, Anders H-J, Basu N, Brouwer E, Gordon J, Jayne DR, et al. ANCA-associated vasculitis. Nature Reviews Disease Primers. 2020 Aug 27;6(1):1–27.[2]Le Gall JR, Lemeshow S, Saulnier F. A new Simplified Acute Physiology Score (SAPS II) based on a European/North American multicenter study. JAMA. 1993 Dec 22;270(24):2957–63.Disclosure of Interests:PETER KORSTEN Speakers bureau: Chugai, Boehringer-Ingelheim, Sanofi Aventis, Abbvie, GSK, Novartis, Consultant of: Lilly, Gilead, Abbvie, Boehringer-Ingelheim, GSK, Novartis, Grant/research support from: GSK, Fabian Kück: None declared, Karaine Tejiozem Donfack: None declared, Radovan Vasko: None declared, Andreas Lena: None declared, Björn Tampe: None declared

Cesiokenopyrochlore, the First Natural Niobate with an Inverse Pyrochlore Structure

Cesiokenopyrochlore is a new mineral belonging to the pyrochlore group. It was discovered in a specimen of granitic pegmatite collected at Tetezantsio, Betafo region, Madagascar. The mineral forms rough equant crystals up to 0.05 mm in size intergrown with béhierite and rynersonite. Cesiokenopyrochlore is light-brown, translucent, with resinous luster. Dcalc. = 5.984 g/cm3. In reflected light it is light gray, isotropic, with strong light-brown internal reflections. The crystal structure was refined to R1 = 0.0212. The mineral is cubic, , a = 10.444(1) Å, V = 1139.5(2) Å3, and Z = 8. The strongest lines of the powder X-ray diffraction pattern [d, Å, (I, %) (hkl)] are: 6.03 (37) (111), 3.70 (9) (220), 3.15 (100) (311), 3.02 (36) (222), 2.012 (17) (511, 333), 1.848 (19) (440), 1.576 (11) (622). The chemical composition is (wt.%; electron microprobe): Cs2O 22.66, Na2O 1.74, CaO 0.64, Nb2O5 20.87, Ta2O5 21.27, WO3 30.67, H2O (calc) 0.12, total 97.97. The empirical formula of the holotype specimen calculated on the basis of (Nb+Ta+W) = 2 apfu and (O+OH) = 6 apfu and written according to the pyrochlore-supergroup nomenclature is Na0.29Ca0.06(Nb0.81W0.69Ta0.50)Σ2[O5.93(OH)0.07]Σ6Cs0.83. The simplified formula of the holotype specimen is □2(Nb,W,Ta)Σ2O6Cs. Cesiokenopyrochlore is the first natural niobate to adopt the inverse pyrochlore structure.

Crystal structure and indicatopy significance of odikhinchaite from the Khibiny alkaline complex

Odikhinchaite, a Sr-Mn-Nb-CO3-dominant eudialyte-group mineral from the Khibiny alkaline complex has been investigated using the methods of electron probe microanalysis, X-ray diffraction, infrared and Mössbauer spectroscopy. The crystal structure was refined to R = 3.4 % in the anisotropic approximation of atomic displacements using 3815 independent reflections with F > 3(F). The unit-cell parameters are: a = 14.2709(1), c = 30.023(1) Å, V = 5295.33(7) Å3; the space group is R3m. The simplified formula of the mineral is (Z = 3): Na11Sr3(Mn2+,Fe2+,Fe3+)Ca6Zr3Nb[Si25O72(OH)](CO3)Cl(OH,O)4. The studied sample is the second find of this rare mineral worldwide, represented by a variety with high Fe content in the M2 micro-region, belonging to the taseqite — odikhinchaite solid-solution series. The significance of odikhinchaite as an indicator of a stage corresponding to maximum Sr activity in specific ultraagpaitic pegmatites is discussed.