Split Function Research Articles

Hypergraphs with edge-dependent vertex weights: p-Laplacians and spectral clustering.

We study p-Laplacians and spectral clustering for a recently proposed hypergraph model that incorporates edge-dependent vertex weights (EDVW). These weights can reflect different importance of vertices within a hyperedge, thus conferring the hypergraph model higher expressivity and flexibility. By constructing submodular EDVW-based splitting functions, we convert hypergraphs with EDVW into submodular hypergraphs for which the spectral theory is better developed. In this way, existing concepts and theorems such as p-Laplacians and Cheeger inequalities proposed under the submodular hypergraph setting can be directly extended to hypergraphs with EDVW. For submodular hypergraphs with EDVW-based splitting functions, we propose an efficient algorithm to compute the eigenvector associated with the second smallest eigenvalue of the hypergraph 1-Laplacian. We then utilize this eigenvector to cluster the vertices, achieving higher clustering accuracy than traditional spectral clustering based on the 2-Laplacian. More broadly, the proposed algorithm works for all submodular hypergraphs that are graph reducible. Numerical experiments using real-world data demonstrate the effectiveness of combining spectral clustering based on the 1-Laplacian and EDVW.

Accuracy of fully automated, AI-generated models compared with validated clinical model to predict post-operative glomerular filtration rate after renal surgery.

693 Background: The American Urologic Association (AUA) recommends estimation of the postoperative glomerular filtration rate (GFR) in patients with a renal mass to help decide between partial nephrectomy (PN) or radical nephrectomy (RN). If postoperative GFR<45 mL/min/1.73m2, a PN should be prioritized. Most existing methods to predict postoperative GFR are rarely implemented in the clinical setting due to complexity. Previously validated models based on clinical equations or kidney volumes from hand-segmented or semi-automated segmentations are quite accurate but have seen limited uptake in clinical practice. We hypothesize that we could develop an artificial intelligence (AI)-GFR prediction that would be calculated automatically on a preoperative computed tomography (CT) scan and predict a postoperative GFR as accurately as a validated clinical model. Methods: 300 patients undergoing PN or RN for renal tumor from the 2021Kidney and Kidney Tumor Segmentation Challenge(KiTS21) were analyzed. We excluded 7 patients having bilateral tumors. Preoperative GFR was the closest recorded value preoperatively and postoperative GFR≥90 days postoperatively. Split-renal-function (SRF) was determined in a fully automated way from preoperative imaging and our previously developed deep learning segmentation model. We programmed the algorithm to estimate postoperative GFR as 1.24×preoperative GFR×contralateral SRF for RN; and as 89% of the preoperative GFR for PN. We compared AI-predicted GFR to a validated clinical model (GFR=35+preoperative GFR(x0.65)-18(if radical nephrectomy)-age(x0.25)+3(if tumor size >7 cm)-2 (if diabetes)). We compared the AI and clinical model estimations of GFR to the measured postoperative GFR using correlation coefficients (R) and compared the ability of AI models to predict a postoperative GFR<45 using logistic regression and AUCs. Results: In 293 patients, the median age was 60 years ((IQR) 51-68), 40.6% were female, and 62.1% had PN. The median tumor size was 4.2 (2.6-6.1), and 91.8% of the tumors were malignant, of which 35.1% were high-grade, 25.6% were high-stage, and 21.8% had necrosis. The median R.E.N.A.L. nephrometry score was 8 (7-9). When comparing measured postoperative GFR, the correlation coefficients were 0.75 and 0.77 for the AI model and clinical models, respectively. For the prediction of a postoperative GFR< 45 ml/min/1.73m2, the AI and clinical models performed similarly (AUC of 0.89 and 0.9, respectively). Conclusions: Our study demonstrates the feasibility of a fully automated prediction of postoperative GFR based on CT imaging and baseline GFR with comparable predictive accuracy to existing validated clinical prediction models. These AI-generated predictions can be implemented for decision-making, with no clinical details, clinician time, or measurements needed.

Management dilemma in pelvi-ureteric junction obstruction: is transit time the answer?

Pelvi-ureteric junction obstruction (PUJO) is the leading cause for hydronephrosis in children. Diuretic renography used in the pre- and post-operative evaluation of pyeloplasty may not be reliable in predicting the outcome. A prospective study was conducted from October 2018 to November 2020, including all children with unilateral PUJO undergoing Pyeloplasty. Renal diuretic renography scans done in the pre and post operative periods were assessed for transit time. The time taken for the isotope to reach the renal pelvis was noted by a single observer as the transit time, from the dynamic frames of the diuretic renogram. Of the 65 children, 74% were boys. The transit time (median) in the preoperative renography was 10min, whereas the same was 4min 45s in the postoperative period, the decrease was statistically significant. On evaluation of transit time with ROC (receiver operating characteristics) curve, a cut-off of 4min and 25s was arrived at, which could identify the delayed drainage reliably. Improvement in transit time is a reliable predictor of renal function improvement after pyeloplasty, comparing favorably in relation to split renal function.

Estimation of differential renal function on routine abdominal imaging employing compressed-sensed contrast-enhanced MR: a feasibility study referenced against dynamic renal scintigraphy in patients with deteriorating renal retention parameters

PurposeTo assess whether high temporal/spatial resolution GRASP MRI acquired during routine clinical imaging can identify several degrees of renal function impairment referenced against renal dynamic scintigraphy.MethodsThis retrospective study consists of method development and method verification parts. During method development, patients subject to renal imaging using gadoterate meglumine and GRASP post-contrast MRI technique (TR/TE 3.3/1.6 ms; FoV320 × 320 mm; FA12°; Voxel1.1 × 1.1x2.5 mm) were matched into four equally-sized renal function groups (no-mild-moderate-severe impairment) according to their laboratory-determined estimated glomerular filtration rates (eGFR); 60|120 patients|kidneys were included. Regions-of-interest (ROIs) were placed on cortices, medullary pyramids and collecting systems of bilateral kidneys. Cortical perfusion, tubular concentration and collecting system excretion were determined as TimeCortex=Pyramid(sec), SlopeTubuli (sec−1), and TimeCollecting System (sec), respectively, and were measured by a combination of extraction of time intensity curves and respective quantitative parameters. For method verification, patients subject to GRASP MRI and renal dynamic scintigraphy (99mTc-MAG3, 100 MBq/patient) were matched into three renal function groups (no-mild/moderate-severe impairment). Split renal function parameters post 1.5–2.5 min as well as MAG3 TER were correlated with time intensity parameters retrieved using GRASP technique; 15|30 patients|kidneys were included.ResultsMethod development showed differing values for TimeCortex=Pyramid(71|75|93|122 s), SlopeTubuli(2.6|2.1|1.3|0.5 s−1) and TimeCollecting System(90|111|129|139 s) for the four renal function groups with partial significant tendencies (several p-values < 0.001). In method verification, 29/30 kidneys (96.7%) were assigned to the correct renal function group.ConclusionHigh temporal and spatial resolution GRASP MR imaging allows to identify several degrees of renal function impairment using routine clinical imaging with a high degree of accuracy.

Predicting new baseline glomerular filtration rate (NBGFR) after donor nephrectomy: Validation of a split renal function (SRF) based formula

Predicting new baseline glomerular filtration rate (NBGFR) after donor nephrectomy: Validation of a split renal function (SRF) based formula

Comparación entre el efecto de la nefrolitotomía percutánea miniaturizada vs. convencional en la función renal evaluada mediante gammagrafía renal con DMSA

Introduction and ObjectivesWe aimed to present a clinical study that compares standard and miniaturized percutaneous nephrolithotomy (PNL) effects on kidney function with scintigraphic imaging in primary kidney stone patients. Materials and MethodsOne hundred four patients were included in this prospective study between May 2014 and February 2017. Eligible patients were divided into two groups miniaturized PNL (mPNL) and standard PNL (sPNL) with matched-pair analysis (1:1 scenario). Technetium-99m Dimercaptosuccinic Acid cortical scintigraphy imaging was performed before and after the operation. ResultsThere were no differences between the two groups in terms of success rate (mPNL(63.5%) vs. sPNL(71.2%), p=0.403), serum creatinine, glomerular filtration rate, split renal functions pre- and postoperatively (p≥0.05). There was no relationship between the type of operation and new scar formation (p=0.780). The rates of serious complication (grades 3 and 4 according to modified Clavien-Dindo Classification) were higher in sPNL (p=0.034). Stone burden, duration of operation, hemoglobin drop, multiple access, blood transfusion, and angioembolization were higher in patients with scarred kidneys (p<0.001, p=0.008, p=0.004, p<0.001, p=0.003, p=0.001, respectively). In multivariate analysis, only multiple access was found statistically significant for predicting new scar formation (p<0.001, OR:24.28). ConclusionsMiniaturized and standard PNL are reliable and successful operations for treating large kidney stones. No significant difference was found between the operation types regarding a decrease in renal function.

Case of the Month from the Peter MacCallum Cancer Centre, Melbourne, Australia: combination of stereotactic ablative body radiotherapy and radical nephrectomy for synchronous bilateral primary renal cell carcinoma.

Case of the Month from the Peter MacCallum Cancer Centre, Melbourne, Australia: combination of stereotactic ablative body radiotherapy and radical nephrectomy for synchronous bilateral primary renal cell carcinoma.

Teflon Injections (STING) Mimicking Distal Ureteric Stones

This case report highlights the potential diagnostic pitfalls associated with subureteral transurethral injection (STING) of non-biodegradable materials like Teflon, which has been utilised for endoscopic correction of vesicoureteral reflux (VUR). A 27-year-old female with a history of VUR presented with left-sided loin pain, vomiting, and dysuria, which were initially thought to be due to distal ureteric stones. However, noncontrast computed tomography (CT) revealed the presence of calcific densities in the region of the distal ureter and vesicoureteric junction (VUJ) bilaterally, likely as a sequelae of previous Teflon injection treatment. A conservative management approach was undertaken, and follow-up evaluations, including MAG3 renograms, showed normal drainage and stable split renal function. This case emphasises the importance of a comprehensive medical history and vigilance in avoiding unnecessary imaging or surgical interventions for patients with a previous history of STING.

Anisotropic structure of the Australian continent

The Australian continent preserves some of the oldest lithosphere on Earth in the Yilgarn, Pilbara, and Gawler Cratons. In this study we present shear wave splitting and Ps receiver function results at long running stations across the continent. We use these results to constrain the seismic anisotropic structure of Australia’s cratons and younger Phanerozoic Orogens. For shear wave splitting analysis, we utilize SKS and SKKS phases at 35 broadband stations. For Ps receiver function analysis, which we use to image horizontal boundaries in anisotropy, we utilize 14 stations. Shear wave splitting results at most stations show strong variations in both orientation of the fast direction and delay time as a function of backazimuth, an indication that multiple layers of anisotropy are present. In general, observed fast directions do not appear to be the result of plate motion alone, nor do they typically follow the strike of major tectonic/geologic features at the surface, although we do point out several possible exceptions. Our Ps receiver function results show significant variations in the amplitude and polarity of receiver functions with backazimuth at most stations across Australia. In general, our results do not show evidence for distinctive boundaries in seismic anisotropy, but instead suggest heterogenous anisotropic structure potentially related to previously imaged mid-lithospheric discontinuities. Comparison of Ps receiver function and shear wave splitting results indicates the presence of laterally variable and vertically layered anisotropy within both the thicker cratonic lithosphere to the west, as well as the Phanerozoic east. Such complex seismic anisotropy and seismic layering within the lithosphere suggests that anisotropic fabrics may be preserved for billions of years and record ancient events linked to the formation, stabilization, and evolution of cratonic lithosphere in deep time.

Outcome of Dismembered Pyeloplasty in Children with Unilateral Pelviureteric Junction Obstruction: A Retrospective Observational Study

Introduction: Anderson-Hynes (AH) dismembered pyeloplasty is the standard procedure performed for the management of Pelviureteric Junction Obstruction (PUJO). Ultrasonography (USG) and diuretic renography are of great importance for the diagnosis and follow-up of PUJO. Aim: To evaluate the morphological and functional outcomes of open dismembered pyeloplasty in children with unilateral PUJO and to find the correlation between functional and morphological outcomes. Materials and Methods: A retrospective observational study was conducted, assessing the clinical charts of 200 children under 10 years of age with congenital PUJO who underwent open AH dismembered pyeloplasty in the Department of Paediatric Surgery at a teritary teaching Institute, Government medical college, Thiruvananthapuram, Kerala, India from from June 2015 to June 2020. The preoperative radiological assessment included renal USG and diuretic renography for all patients. Morphological and functional surgical outcomes were measured one year after surgery. The morphologic parameters analysed were the Anteroposterior Diameter (APD) of the pelvis and Parenchymal Thickness (PT). The functional outcome was assessed by improvements in Glomerular Filtration Rate (GFR), Split Renal Function (SRF), and drainage curve. Success was defined as improvement in function and morphology in followup USG and renogram after one year of surgery. Paired t-test was applied for statistical analysis using Statistical Package for the Social Sciences (SPSS) software version 23.0. Results: Among the total 200 patients,180 (90%) cases demonstrated improved renal function after pyeloplasty. Among the total 200 cases, males were 120 (60%) and females were 80 (40%). Morphologic outcome improved in 188 out of 200 (94%) cases. The overall outcome was good in 168 out of 200 (84%) patients. The results showed a moderate negative correlation for APD with respect to SRF (r=-0.677, p-value=0.01) and GFR (r=- 0.430, p-value=0.01), whereas a moderate positive correlation was observed between SRF and GFR (r=0.423, p-value=0.01). Conclusion: AH dismembered pyeloplasty is an effective treatment for PUJO in children, not only relieving obstruction but also improving renal function. The present study recommends considering both morphologic and functional parameters to assess the success of the surgery.

99mTc-DTPA Renal Dynamic Imaging for Evaluating the Function of Duplex Kidneys in Adult Patients.

This study aimed to explore technetium-99m-diethylenetriaminepentaacetic acid (99mTc-DTPA) renal dynamic imaging to evaluate duplex kidney function in adult patients. We retrospectively analyzed the clinical data of 25 patients with duplex kidneys who underwent 99mTc-DTPA renal dynamic imaging between June 2011 and March 2023 at our hospital. Patients in the duplex kidney group (n = 25) were divided into renogram normal (n = 9) and abnormal (n = 16) groups according to the imaging data. Additionally, normal patients were selected as the control group (n = 25). After imaging, the region of interest of the kidneys was delineated, and renography was performed. Renography can provide renal function parameters, including glomerular filtration rate (GFR), Tmax, T1/2, renal clearance, and the GFR ratio of the duplex renal segment (upper renal moiety). Compared with the control group, the serum creatinine level in the duplex kidney group was higher (p = 0.025), GFR was lower (p = 0.001), and patients with impaired renal function were mainly in the abnormal renography group (p = 0.001). In the duplex kidney group, the GFR (p = 0.026) and renal clearance (p = 0.006) of the affected kidneys were lower than those of the contralateral kidneys, and Tmax (p = 0.025) was higher than that of the contralateral kidneys. There were no differences in renal function indicators of duplex renal segments with different GFR ratios. However, when the GFR ratio exceeded 50%, the renal function tended to decline. 99mTc-DTPA renal dynamic imaging was found useful to evaluate the total renal function, split renal function, and upper urinary tract patency in patients with duplex kidneys. Patients with abnormal renography results had worse renal function, and those with poor renal clearance in the affected renal moiety required surgical treatment.

Tc-99m DMSA SPECT for Follow-Up of Non-Operative Treatments in Renal Injuries: A Prospective Single-Center Study.

The assessment of cortical integrity following renal injuries with planar Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy depends on measuring relatively decreased cortical uptake (i.e., split renal function [SRF]). We analyzed the additive values of the volumetric and quantitative analyses of the residual cortical integrity using single-photon emission computed tomography (SPECT) compared to the planar scintigraphy. This prospective study included 47 patients (male:female, 32:15; age, 47 ± 22 years) who had non-operatively managed renal injuries and underwent DMSA planar and SPECT imaging 3-6 months after the index injury. In addition to planar SRF, SPECT SRF, cortical volume, and absolute cortical uptake were measured for the injured kidney and both kidneys together. The correlations of planar SRF with SPECT SRF and those of SRF with volumetric/quantitative parameters obtained with SPECT were analyzed. The association of SPECT parameters with renal function, grades of renal injuries, and the risk of renal failure was also analyzed. SPECT SRF was significantly lower than planar SRF, with particularly higher biases in severe renal injuries. Planar and SPECT SRF (dichotomized with a cutoff of 45%) showed 19%-36% of discrepancies with volumetric and quantitative DMSA indices (when dichotomized as either high or low). Absolute cortical uptake of the injured kidney best correlated with glomerular filtration rate (GFR) at follow-up (ρ = 0.687, P < 0.001) with significant stepwise decreases by GFR strata (90 and 60 mL/min/1.73 m²). Total renal cortical uptake was significantly lower in patients with moderate-to-high risk of renal failure than those with low risk. However, SRF did not reflect GFR decrease below 60 mL/min/1.73 m² or the risk of renal failure, regardless of planar or SPECT (count- or volume-based SRF) imaging. Quantitative measurements of renal cortical integrity assessed with DMSA SPECT can provide more clinically relevant and comprehensive information than planar imaging or SRF alone.

Medium-modifications of g → cc splitting

We study medium-modifications of the gluon splitting into a quark and anti-quark pair. Applying the Baier-Dokshitzer-Mueller-Peigné-Schiff and Zakharov (BDMPS-Z) formalism, we derive a path-integral formula for the in-medium g → qq¯ splitting function in the close-to-eikonal limit. Our analysis shows that there are two qualitatively different medium effects: transverse momentum broadening of qq¯ pairs and enhanced production of such pairs. We note that both effects are numerically sizeable if the average momentum transfer from the medium to the parton is at the quark mass scale. In ultra-relativistic heavy-ion collisions, this condition is realized by charm quarks, therefore we focus our numerical analysis on the medium-modifications of g → cc¯ splitting.

Terahertz multibeam modulation reflection-coded metasurface

Most of reported coding metasurfaces only use phase encoding or amplitude encoding to regulate electromagnetic waves, which limits the flexibility of terahertz wave regulation. In this work, a metasurface element structure is proposed. The metasurface element is composed of three layers, i.e. metal pattern structure layer, intermediate medium layer, and metal base layer. According to the geometric phase principle, the phase coverage in the 2π range can be achieved by rotating the metal pattern structure layer under the incidence of the circular-polarized terahertz wave. The metasurface element structure is arranged reasonably by using the phase coding, and the 1-bit and 2-bit phase coding metasurface are designed. First of all, the coding metasurface with interlacing “0” and “1” is designed to generate a double beam reflection under the vertical incidence of circular polarized terahertz waves, while the two-dimensional checkerboard coding metasurface with “0” and “1” generates a symmetrical four-beam reflection. In addition, the metasurface is designed to deflect the reflected beam, and the coding period is changed to design the metasurface to deflect the reflected beam to the specified angle, showing good flexibility. Finally, the convolutional operation is introduced to flexibly regulate the circular polarized beam, and the functions of beam splitting and reflection beam deflection are obtained. The amplitude coded metasurface is designed under theincidence of the online polarized terahertz wave, and the near-field imaging effect can be realized by the amplitude differentiation of polarization reflection. The designed amplitude coded metasurface realizes the function of imaging in space, presenting the designed “CJLU” pattern, which has different imaging effects at different observation locations. When the observation plane distance is 80 μm at the observation frequency of 1.22 THz, the near-field imaging effect is best. In conclusion, we propose a terahertz multibeam modulation reflection-coded metasurface, which combines geometric phase and amplitude variation to achieve different terahertz wave modulation functions under different polarization incident terahertz waves. The results from the simulated near-field radiation model and the far-field radiation model are both in agreement with the theoretical calculation predictions. The designed metasurface provides a degree of freedom method for terahertz wave polarization and phase manipulation, which greatly improves the efficiency of terahertz wave manipulation and has potential applications in terahertz systems.

The application of artificial technology in pediatric pyeloplasty the efficacy analysis of robotic-assisted laparoscopic pyeloplasty in the treatment of ureteropelvic junction obstruction.

To investigate the clinical effect of the da Vinci robotic-assisted laparoscopic pyeloureteroplasty (RALP) in treating pediatric ureteropelvic junction obstruction (UPJO). We retrospectively analyzed clinical data from 32 children with UPJO who suffered from RALP in our hospital from October 2020 to February 2023, compared with those treated with common laparoscopy at the same time. After the establishment of the robotic arm, a mesenteric approach was performed after entering the abdominal cavity to focus on the lesion site. The dilated renal pelvis was then cut and the stenotic ureter was removed; the anastomosis and the incision were sutured by layer. A total of 62 children (44 boys and 20 girls) with a median age of 14 months (ranging from 3 to 38 months) were included. All 62 cases had hydronephrosis caused by unilateral UPJO, and the surgery was successfully completed without conversion to open. All intraoperative blood losses amounted to less than 10 ml. In the RALP group, the average operative duration was 131.28 min (ranging from 108 to 180 min). The average catheter time was 3.66 days (ranging from 2 to 7 days). The average hematuria time was 3.84 days (ranging from 2 to 6 days). The average postoperative hospital stay was 7.8 days (ranging from 6 to 12 days). The average hospitalization costs were 59,048.31 yuan (ranging from 50,484 to 69,977 yuan). The double-J tube was removed 1 month after surgery. Only one patient suffered from complications, developing a urinary tract infection 4 weeks after surgery, and was cured with the administration of oral cefaclor anti-inflammatory drugs for 3 days. All patients were followed up for 2-28 months, with a median follow-up time of 12 months. The thickness of the renal cortex was increased after surgery [(1.95 ± 0.24) vs. (4.82 ± 0.50)] cm, and the isotope renograms revealed a definite recovery of the split renal function [(28.32 ± 1.95) vs. (37.01 ± 2.71)]%. The robotic-assisted laparoscopic pyeloureteroplasty (RALP) in the treatment of children with upper ureteral obstruction has overall clinical efficiency. With technological advancements and an increased number of experienced surgeons, robotic surgery may become a new trend in surgery.

An Innovative Miniaturized Cell Imaging System Based on Integrated Coaxial Dual Optical Path Structure and Microfluidic Fixed Frequency Sample Loading Strategy

On-site rapid detection of cells is especially of concern for many fields, image-based detection results can directly reflect the multi-dimensional information such as cell contour and aggregation state. This article proposes an innovative miniaturized cell imaging system based on integrated coaxial dual optical path structure and microfluidic fixed frequency sample loading strategy, which performs synchronous imaging of bright field mode and fluorescence field mode on cells. The bright field optical path and fluorescence field optical path are integrated into the coaxial dual optical path structure based on the dichroic mirror with splitting and steering functions. The movement of the shutter’s curtain is controlled by a micro-motor, so that the plane mirrors fixed on the curtain with different light angle can be switched to the optical axis, and the fast switching of the bright field optical path and the fluorescence field optical path can be implemented. A drawer-type filter module can be pulled out of the coaxial dual optical path structure, the emission filter and the dichroic mirror in this module can be replaced according to the fluorescence emission peak of the sample to be tested, thereby expanding the detectable cell types of this system. In addition, based on the force analysis and calculation of the fluid, a fixed frequency was obtained to drive the sample loading. The accumulated kinetic energy of the fluid during this period can be offset by the closing of the pinch valve, and the flow rate of the sample in the imaging field can be rapidly reduced to close to zero to avoid the tailing effect in the image. It is experimentally confirmed that the detection accuracy of this system, the registration matching accuracy of cells and fluorescent dots, the cell survival rate, and the detection sensitivity of cell viability. This system balances the tradeoff between portability, flux and accuracy, offers more functionality in terms of technology and application for on-site cell detection.

Effects Of Pyeloplasty in Infants with Failing Kidneys Over the Long Term

Objective: The most typical type of obstruction in the upper urinary tract is ureteropelvic junction obstruction or UPJO. The objective of this study was to assess the effectiveness and long-term results of pyeloplasty in children with poorly functioning kidneys. Method: Patients who underwent pyeloplasty at Department of Urology, Rajendra Institute of Medical Science, Ranchi for last twelve years were the subject of a retrospective data study. Postoperative outcome was the parameter under study. Success was measured by either symptom improvement or better drainage on postoperative Tc-99m DTPA renography, which was performed after two months and then yearly after that. Results: 60 individuals were enrolled in the study, with a mean age of 8.5 years (3 months to 12 years), a male-to-female ratio of 2:1, and poor function on the isotope renogram (31%). The ratio of left to right sides was 1.2:1. All patients had dismembered pyeloplasty procedures. 37 patients (66.8%) underwent laparoscopic pyeloplasty, whereas 23 (33.2%) underwent open surgery. 35 patients had follow-up renograms available; of these, 30 showed improved drainage and no further decline in renal function, while 5 displayed an obstructed pattern; of these, 3 patients had noticeably worsened split function, and the other two underwent a second open pyeloplasty. A mean follow-up of 21.5 months revealed a 91% overall success rate. Conclusion: In the pediatric age group, pyeloplasty provides satisfactory intermediate results in kidneys with inadequate function.

Stability for discrete time waveform relaxation methods based on Euler schemes

&lt;abstract&gt;&lt;p&gt;Stability properties of discrete time waveform relaxation (DWR) methods based on Euler schemes are analyzed by applying them to two dissipative systems. Some sufficient conditions for stability of the considered methods are obtained; at the same time two examples of instability are given. To investigate the influence of the splitting functions and underlying numerical methods on stability of DWR methods, DWR methods based on different splittings and different numerical schemes are considered. The obtained results show that the stabilities of waveform relaxation methods based on an implicit Euler scheme are better than those based on explicit Euler scheme, and that the stabilities of waveform relaxation methods based on the classical splittings such as Gauss-Jacobi and Gauss-Seidel splittings are worse than those based on the eigenvalue splitting presented in this paper. Finally, numerical examples that confirm the theoretical results are presented.&lt;/p&gt;&lt;/abstract&gt;

CT volumetry performs better than nuclear renography in predicting estimated renal function one year after living donation

The evaluation of split renal function (SRF) is a critical issue in living kidney donations and can be evaluated using nuclear renography (NR) or computerized tomography (CT), with unclear comparative advantages. We conducted this retrospective study in 193 donors to examine the correlation of SRF assessed by NR and CT volumetry and compared their ability to predict remaining donor renal function at 1 year, through multiple approaches. A weak correlation between imaging techniques for evaluating the percentage of the remaining kidney volume was found in the global cohort, with an R2 = 0.15. However, the Bland–Altman plot showed an acceptable agreement (95% of the difference between techniques falling within − 8.51 to 6.11%). The predicted and observed eGFR one year after donation were calculated using the CKD-EPI, and CG/BSA equations. CT volume showed a better correlation than NR for both formulas (adjusted R2 of 0.42. and 0.61 vs 0.37 and 0.61 for CKD-EPI and CG/ BSA equations, respectively). In non-nested modeling tests, CT volumetry was significantly superior to NR for both equations. CT volumetry performed better than NR in predicting the estimated renal function of living donors at 1-year, independently from the eGFR equation.

Constraining 3-D variations in mantle attenuation using normal modes: forward modelling and sensitivity tests

SUMMARY Robust estimates of the Earth’s temperature, composition and partial melt are difficult to obtain from seismic tomography models based only on wave velocities. Seismic attenuation is able to add crucial additional information and allows us to constrain 3-D variations in temperature as well as answer fundamental questions regarding the presence of water and partial melt within the mantle. A major problem with measuring attenuation is that scattering and focusing effects need to be included in order to distinguish between intrinsic attenuation (transformation of energy to heat) and scattering (redistribution of energy). Here, we will use whole Earth oscillations or normal modes, exploiting the fact that small scale scattering becomes less important at longer periods. In addition, focussing is implicitly included by simultaneously measuring the elastic and anelastic splitting function of a given normal mode. Normal mode data has rarely been used before to constrain 3-D variations in attenuation, hence we first need to assess the feasibility of using whole Earth oscillations to image 3-D variations in attenuation in Earth’s upper and lower mantle. Here, we use simple models in forward calculations to evaluate the sensitivity of normal modes to 3-D attenuation variations, and find observable differences in normal mode spectra when 3-D variations in mantle attenuation are included. We also test if 3-D attenuation variations can be recovered using splitting function measurements for synthetic normal mode spectra and investigate potential problems with unaccounted earthquake magnitude variations, noise and wide-band cross-coupling between modes. We find that we are able to recover input synthetic anelastic splitting functions, even when they are an order of magnitude smaller than the elastic splitting functions. Biases in the earthquake seismic moment solutions may lead to ‘ghost’ anelastic splitting functions being recovered, especially for high degree structure. However, this ‘ghost’ signal is only relevant if the size of the input anelastic splitting function is 50 per cent smaller than the scaled amplitude signal of expected upper mantle attenuation. Random noise and normal mode coupling also lead to spurious effects in the anelastic splitting functions. However, they manly affect high degree anelastic structure in a non-branch consistent manner. Thus, we are able to robustly recover low anelastic degree structure (smax ≤ 4) in all tested cases.