Matching matched filtering with deep networks in gravitational-wave astronomy

We report on the construction of a deep convolutional neural network that can reproduce the sensitivity of a matched-filtering search for binary black hole gravitational-wave signals. The standard method for the detection of well modeled transient gravitational-wave signals is matched filtering. However, the computational cost of such searches in low latency will grow dramatically as the low frequency sensitivity of gravitational-wave detectors improves. Convolutional neural networks provide a highly computationally efficient method for signal identification in which the majority of calculations are performed prior to data taking during a training process. We use only whitened time series of measured gravitational-wave strain as an input, and we train and test on simulated binary black hole signals in synthetic Gaussian noise representative of Advanced LIGO sensitivity. We show that our network can classify signal from noise with a performance that emulates that of match filtering applied to the same datasets when considering the sensitivity defined by Reciever-Operator characteristics.Comment: 5 pages, 3 figures, submitted to PR

Modeling and Tracking Degradation in Electronic Components

This dissertation develops models for electrical components that are useful for describing or predicting their behavior in certain applications. The three models presented are physics-based models that not only describe the behavior, but provide valuable insight as to how the component design relates to the electrical behavior. In the first chapter of this dissertation, ringing in a power inverter circuit is analyzed and used to track degradation that occurs to the inverter transistors. This is accomplished via the Matrix Pencil Method, which extracts frequency and damping information from the complex poles of a system response. A shift in the pole location of a system response is indicative of transistor degradation. The second chapter explores modeling multi-layer ceramic capacitors (MLCCs). A simple, accurate model is developed which is based on the physical construction of the capacitor. This model utilizes frequency-dependent resistance terms and mutual inductance to model the frequency-dependent behavior of the capacitor impedance and equivalent series resistance (ESR). The final chapter studies the contribution of non-linear behavior of MLCCs to the ESR of the capacitor. MLCCs are known to exhibit non-linear behavior in which their capacitance varies with the applied voltage. This causes distortion in the time domain and harmonics in the frequency domain. Power is shifted from the fundamental frequency to harmonics of the fundamental frequency, which will appear as a loss at the fundamental under most circumstances. In some cases, the apparent loss at the fundamental may be comparable to the ESR of the capacitor

Comparison of Estimated Glomerular Filtration Rate Using Five Equations to Predict Acute Kidney Injury Following Total Joint Arthroplasty

Introduction: Primary total joint arthroplasty (TJA) is one of the most common procedures in the United States, and as the incidence of this surgery increases, identifying methods for improving outcomes and reducing complications is essential. Acute kidney injury (AKI) following TJA is a potential source of morbidity and mortality. Estimated glomerular filtration rate (eGFR) is used as an indicator of renal function. Several equations are commonly used to calculate eGFR. The purpose of this study was 1) to evaluate the agreement between five equations in calculating eGFR, and 2) to confirm which equation can best predict AKI in patients undergoing TJA. Methods: 497,261 cases of TJA were queried from the National Surgical Quality Improvement Program (NSQIP) from 2012 to 2019. Preoperative eGFR was calculated using the Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD) II, re-expressed MDRD II, Chronic Kidney Disease Epidemiology Collaboration, and Mayo quadratic (Mayo) equations. The primary outcome measure was acute kidney injury (AKI). These cohorts were compared based on demographic and preoperative factors. Multivariate regression analysis was used to evaluate independent associations between preoperative eGFR and postoperative renal outcomes. Results: Seven hundred seventy-seven (0.16%) patients experienced AKI after TJA. The Cockcroft-Gault equation yielded the highest mean eGFR (98.6 ± 32.7), while the Re-expressed MDRD II equation yielded the lowest mean eGFR (75.1 ± 28.8). Multivariate regression analysis showed that a decrease in preoperative eGFR was independently associated with an increased risk of postoperative AKI in all five equations. The Akaike information criterion (AIC) was the lowest in the Mayo equation (6546). Conclusions: Preoperative decrease in eGFR in all five equations was independently associated with increased risk of postoperative AKI. The Mayo equation had the highest predictive ability of acquiring postoperative AKI following TJA

Not All Patients Need Supervised Physical Therapy After Primary Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.

Although postoperative physical therapy (PT) has long been considered essential to successful total knee arthroplasty (TKA) recovery, recent literature has suggested that unsupervised home exercise regimens may offer similar benefits to formal supervised sessions. We aimed to compare objectively measured physical function and subjective patient-reported outcomes (PROs) between primary TKA patients who received formal supervised physical therapy sessions and those who received unsupervised home exercise regimens after discharge. Six electronic databases were queried to identify randomized controlled trials comparing supervised physical therapy to unsupervised home exercise regimens in primary TKA patients after discharge. Outcomes of interest included change from baseline in objective measures (knee flexion range of motion (ROM), lower extremity strength, and aerobic capacity) and PROs (physical function and quality of life scores). These outcomes were subdivided into short-term (surgery; closest data point to three months is used if multiple measurements were made in this time period) and long-term (≥6 months from surgery; closest data point to 12 months is used if multiple measurements were made in this time period) assessments. A total of 1,884 cases performed in 11 studies were included in this review. There were no significant differences between cohorts with regard to short-term knee flexion ROM (p = 0.7), lower extremity strength (p = 0.6), or patient-reported quality of life (p = 0.5), as well as long-term knee flexion ROM (p = 0.7), patient-reported quality of life (p = 0.2), or patient-reported physical outcome scores (p = 0.3). A small difference in short-term patient-reported physical outcomes was observed in favor of the supervised cohort (standardized mean difference (SMD): 0.3 (95% confidence interval (CI): 0.01, 0.6); I2 = 82%; p = 0.04). Formal supervised physical therapy regimens do not confer clinically significant benefits over unsupervised home exercise regimens following primary TKA. The routine use of supervised physical therapy after discharge may not be warranted. Further study is needed to determine the subset of patients that may benefit from supervised care

Topological network alignment uncovers biological function and phylogeny

Sequence comparison and alignment has had an enormous impact on our understanding of evolution, biology, and disease. Comparison and alignment of biological networks will likely have a similar impact. Existing network alignments use information external to the networks, such as sequence, because no good algorithm for purely topological alignment has yet been devised. In this paper, we present a novel algorithm based solely on network topology, that can be used to align any two networks. We apply it to biological networks to produce by far the most complete topological alignments of biological networks to date. We demonstrate that both species phylogeny and detailed biological function of individual proteins can be extracted from our alignments. Topology-based alignments have the potential to provide a completely new, independent source of phylogenetic information. Our alignment of the protein-protein interaction networks of two very different species--yeast and human--indicate that even distant species share a surprising amount of network topology with each other, suggesting broad similarities in internal cellular wiring across all life on Earth.Comment: Algorithm explained in more details. Additional analysis adde

Predictive Factors and Outcomes in Patients With Severe Postoperative Anemia Following Total Joint Arthroplasty

Background: Perioperative allogenic blood transfusions (ABT) have demonstrated associations with poor outcomes and increased complication rates following total joint arthroplasty (TJA). Recent strides in blood conservation methods have been made, including multimodal blood management, tranexamic acid (TXA) use, and restrictive transfusion strategies in order to reduce risk associated with transfusion. While the literature on transfusions and outcomes is extensive, the consequences of low postoperative hemoglobin is less well defined. This study aimed to identify factors and consequences associated with severe anemia (hemoglobin \u3c8g/dL) following primary TJA. Methods: A retrospective review was conducted of all the elective primary TJA at a single tertiary care medical center from January 2017 to December 2018. One thousand six hundred and thirty-five cases were stratified based on the development of severe postoperative anemia, and compared based on patient preoperative hemoglobin, comorbidities, demographics, intraoperative variables, and postoperative outcomes. Logistic regression was used to identify independent predictors of severe postoperative anemia. Results: Surgical duration (per 30 minute increase) (OR, 2.03; 95% CI, 1.59-2.58), preoperative hemoglobin (per 1g/dL decrease) (odds ratio [OR], 2.96; 95% confidence interval [CI], 2.38-6.38), and THA vs. TKA (OR, 2.06; 95% CI 1.26-3.37) were independently associated with severe postoperative anemia. Use of TXA (OR, 0.42; 0.20-0.85), and body mass index (per 1kg/m2 increase) (OR, 0.90; 95% CI, 0.86-0.95) were protective against it. Severe postoperative anemia was associated with acute kidney injury (AKI), longer length of stay (LOS), and 90-day emergency department visits/readmissions. Conclusions: Longer duration of surgery, lower preoperative hemoglobin, and THA are all associated with severe postoperative anemia, and lead to complications of AKI, increased LOS, and higher readmission rates. As the incidence of fast-track TJA and outpatient surgery steadily increase, reducing the extent of postoperative anemia is essential for patient outcomes

A Weakly nonlinear theory for spiral density waves excited by accretion disc turbulence

We develop an analytic theory to describe spiral density waves propagating in a shearing disc in the weakly nonlinear regime. Such waves are generically found to be excited in simulations of turbulent accretion disks, in particular if said turbulence arises from the magneto-rotational instability (MRI). We derive a modified Burgers equation governing their dynamics, which includes the effects of nonlinear steepening, dispersion, and a bulk viscosity to support shocks. We solve this equation approximately to obtain nonlinear sawtooth solutions that are asymptotically valid at late times. In this limit, the presence of shocks is found to cause the wave amplitude to decrease with time as 1/t^2. The validity of the analytic description is confirmed by direct numerical solution of the full nonlinear equations of motion. The asymptotic forms of the wave profiles of the state variables are also found to occur in MRI simulations indicating that dissipation due to shocks plays a significant role apart from any effects arising from direct coupling to the turbulence

Unsupervised Home Exercises Versus Formal Physical Therapy After Primary Total Hip Arthroplasty: A Systematic Review

Historically, postoperative exercise and physical therapy (PT) have been viewed as crucial to a successful outcome following primary total hip arthroplasty (THA). This systematic review and meta-analysis aimed to assess differences in both short- and long-term objective and self-reported measures between primary THA patients with formal supervised physical therapy versus unsupervised home exercises after discharge. A search was conducted of six electronic databases from inception to December 14, 2020, for randomized controlled trials (RCTs) comparing changes from baseline in lower extremity strength (LES), aerobic capacity, and self-reported physical function and quality of life (QoL) between supervised and unsupervised physical therapy/exercise regimens following primary THA. Outcomes were separated into short-term (surgery, closest to 3 months) and long-term (≥6 months from surgery, closest to 12 months) measures. Meta-analyses were performed when possible and reported in standardized mean differences (SMDs) with 95% confidence intervals (CI). Seven studies (N=398) were included for review. No significant differences were observed with regard to lower extremity strength (p=0.85), aerobic capacity (p=0.98), or short-term quality of life scores (p=0.18). Although patients in supervised physical therapy demonstrated improved short-term self-reported outcomes compared to those performing unsupervised exercises, this was represented by a small effect size (SMD 0.23 [95% CI, 0.02-0.44]; p=0.04). No differences were observed between groups regarding long-term lower extremity strength (p=0.24), physical outcome scores (p=0.37), or quality of life (p=0.14). The routine use of supervised physical therapy may not provide any clinically significant benefit over unsupervised exercises following primary THA. These results suggest that providers should reconsider the routine use of supervised physical therapy after discharge

Radioiodination of sulfhydryl-sensitive proteins

A new procedure is described for the radioiodination of proteins with sulfhydryl groups essential for their biological activity. Aniline is iodinated with 125I-labeled sodium iodide in the presence of chloramine-T, the product separated by solvent extraction, diazotized and coupled to protein.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22016/1/0000432.pd