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BACKGROUND The use of electronic clinical decision support (CDS) systems for pediatric critical care trials is rare. We sought to describe in detail the use of a CDS tool (Children's Hospital Euglycemia for Kids Spreadsheet [CHECKS]), for the management of hyperglycemia during the 32 multicenter Heart And Lung Failure-Pediatric Insulin Titration trial. RESEARCH QUESTION In critically ill pediatric patients who were treated with CHECKS, how was user compliance associated with outcomes; and what patient and clinician factors might account for the observed differences in CHECKS compliance? STUDY DESIGN AND METHODS During an observational retrospective study of compliance with a CDS tool used during a prospective randomized controlled trial, we compared patients with high and low CHECKS compliance. We investigated the association between compliance and blood glucose metrics. We describe CHECKS and use a computer interface analysis framework (the user, function, representation, and task analysis framework) to categorize user interactions. We discuss implications for future randomized controlled trials. RESULTS Over a 4.5-year period, 658 of 698 children were treated with the CHECKS protocol for ≥24 hours with a median of 119 recommendations per patient. Compliance per patient was high (median, 99.5%), with only 30 patients having low compliance (

Objectives We explored the age-dependent heterogeneity in the efficacy of prophylaxis with enoxaparin against central venous catheter-associated deep venous thrombosis in critically ill children. Design Post hoc analysis of a Bayesian phase 2b randomized clinical trial. Setting Seven PICUs. Patients Children less than 18 years old with newly inserted central venous catheter. Interventions Enoxaparin started less than 24 hours after insertion of central venous catheter and adjusted to anti-Xa level of 0.2-0.5 international units/mL versus usual care. Measurements and main results Of 51 children randomized, 24 were infants less than 1 year old. Risk ratios of central venous catheter-associated deep venous thrombosis with prophylaxis with enoxaparin were 0.98 (95% credible interval, 0.37-2.44) in infants and 0.24 (95% credible interval, 0.04-0.82) in older children greater than or equal to 1 year old. Infants and older children achieved anti-Xa level greater than or equal to 0.2 international units/mL at comparable times. While central venous catheter was in situ, endogenous thrombin potential, a measure of thrombin generation, was 223.21 nM.min (95% CI, 8.78-437.64 nM.min) lower in infants. Factor VIII activity, a driver of thrombin generation, was also lower in infants by 45.1% (95% CI, 15.7-74.4%). Median minimum platelet count while central venous catheter was in situ was higher in infants by 39 × 103/mm3 (interquartile range, 17-61 × 103/mm3). Central venous catheter:vein ratio was not statistically different. Prophylaxis with enoxaparin was less efficacious against central venous catheter-associated deep venous thrombosis at lower factor VIII activity and at higher platelet count. Conclusions The relatively lesser contribution of thrombin generation on central venous catheter-associated thrombus formation in critically ill infants potentially explains the age-dependent heterogeneity in the efficacy of prophylaxis with enoxaparin.

Objectives We obtained preliminary evidence on the efficacy of early prophylaxis on the risk of central venous catheter-associated deep venous thrombosis and its effect on thrombin generation in critically ill children. Design Bayesian phase 2b randomized clinical trial. Setting Seven PICUs. Patients Children less than 18 years old with a newly inserted central venous catheter and at low risk of bleeding. Intervention Enoxaparin adjusted to anti-Xa level of 0.2-0.5 international units/mL started at less than 24 hours after insertion of central venous catheter (enoxaparin arm) versus usual care without placebo (usual care arm). Measurements and main results At the interim analysis, the proportion of central venous catheter-associated deep venous thrombosis on ultrasonography in the usual care arm, which was 54.2% of 24 children, was significantly higher than that previously reported. This resulted in misspecification of the preapproved Bayesian analysis, reversal of direction of treatment effect, and early termination of the randomized clinical trial. Nevertheless, with 30.4% of 23 children with central venous catheter-associated deep venous thrombosis on ultrasonography in the enoxaparin arm, risk ratio of central venous catheter-associated deep venous thrombosis was 0.55 (95% credible interval, 0.24-1.11). Including children without ultrasonography, clinically relevant central venous catheter-associated deep venous thrombosis developed in one of 27 children (3.7%) in the enoxaparin arm and seven of 24 (29.2%) in the usual care arm (p = 0.02). Clinically relevant bleeding developed in one child randomized to the enoxaparin arm. Response profile of endogenous thrombin potential, a measure of thrombin generation, was not statistically different between trial arms. Conclusions These findings suggest the efficacy and safety of early prophylaxis that should be validated in a pivotal randomized clinical trial.

Previous studies report worse short-term outcomes with hypoglycemia in critically ill children. These studies relied on intermittent blood glucose measurements, which may have introduced detection bias. We analyzed data from the Heart And Lung Failure-Pediatric INsulin Titration trial to determine the association of hypoglycemia with adverse short-term outcomes in critically ill children.Nested case-control study.Thirty-five PICUs. A computerized algorithm that guided the timing of blood glucose measurements and titration of insulin infusion, continuous glucose monitors, and standardized glucose infusion rates were used to minimize hypoglycemia.Nondiabetic children with cardiovascular and/or respiratory failure and hyperglycemia. Cases were children with any hypoglycemia (blood glucose60 mg/dL), whereas controls were children without hypoglycemia. Each case was matched with up to four unique controls according to age group, study day, and severity of illness.None.A total of 112 (16.0%) of 698 children who received the Heart And Lung Failure-Pediatric INsulin Titration protocol developed hypoglycemia, including 25 (3.6%) who developed severe hypoglycemia (blood glucose40 mg/dL). Of these, 110 cases were matched to 427 controls. Hypoglycemia was associated with fewer ICU-free days (median, 15.3 vs 20.2 d; p = 0.04) and fewer hospital-free days (0 vs 7 d; p = 0.01) through day 28. Ventilator-free days through day 28 and mortality at 28 and 90 days did not differ between groups. More children with insulin-induced versus noninsulin-induced hypoglycemia had zero ICU-free days (35.8% vs 20.9%; p = 0.008). Outcomes did not differ between children with severe versus nonsevere hypoglycemia or those with recurrent versus isolated hypoglycemia.When a computerized algorithm, continuous glucose monitors and standardized glucose infusion rates were used to manage hyperglycemia in critically ill children with cardiovascular and/or respiratory failure, severe hypoglycemia (blood glucose40 mg/dL) was uncommon, but any hypoglycemia (blood glucose60 mg/dL) remained common and was associated with worse short-term outcomes.

Objectives To evaluate the effect of a tracheal intubation safety bundle on adverse tracheal intubation-associated events across 15 PICUs. Design Multicenter time-series study. Setting PICUs in the United States. Patients All patients received tracheal intubations in ICUs. Interventions We implemented a tracheal intubation safety bundle as a quality-improvement intervention that includes: 1) quarterly site benchmark performance report and 2) airway safety checklists (preprocedure risk factor, approach, and role planning, preprocedure bedside "time-out," and immediate postprocedure debriefing). We define each quality-improvement phase as baseline (-24 to -12 mo before checklist implementation), benchmark performance reporting only (-12 to 0 mo before checklist implementation), implementation (checklist implementation start to time achieving > 80% bundle adherence), early bundle adherence (0-12 mo), and sustained (late) bundle adherence (12-24 mo). Bundle adherence was defined a priori as greater than 80% of checklist use for tracheal intubations for 3 consecutive months. Measurements and main results The primary outcome was the adverse tracheal intubation-associated event, and secondary outcomes included severe tracheal intubation-associated events, multiple tracheal intubation attempts, and hypoxemia less than 80%.From January 2013 to December 2015, out of 19 participating PICUs, 15 ICUs (79%) achieved bundle adherence. Among the 15 ICUs, the adverse tracheal intubation-associated event rates were baseline phase: 217/1,241 (17.5%), benchmark reporting only phase: 257/1,750 (14.7%), early 0-12 month complete bundle compliance phase: 247/1,591 (15.5%), and late 12-24 month complete bundle compliance phase: 137/1,002 (13.7%). After adjusting for patient characteristics and clustering by site, the adverse tracheal intubation-associated event rate significantly decreased compared with baseline: benchmark: odds ratio, 0.83 (0.72-0.97; p = 0.016); early bundle: odds ratio, 0.80 (0.63-1.02; p = 0.074); and late bundle odds ratio, 0.63 (0.47-0.83; p = 0.001). Conclusions Effective implementation of a quality-improvement bundle was associated with a decrease in the adverse tracheal intubation-associated event that was sustained for 24 months.

Oxygen desaturation during tracheal intubation is known to be associated with adverse ICU outcomes in critically ill children. We aimed to determine the occurrence and severity of desaturation during tracheal intubations and the association with adverse hemodynamic tracheal intubation-associated events.Retrospective cohort study as a part of the National Emergency Airway Registry for Children Network's quality improvement project from January 2012 to December 2014.International PICUs.Critically ill children younger than 18 years undergoing primary tracheal intubations in the ICUs.tracheal intubation processes of care and outcomes were prospectively collected using standardized operational definitions. We defined moderate desaturation as oxygen saturation less than 80% and severe desaturation as oxygen saturation less than 70% during tracheal intubation procedures in children with initial oxygen saturation greater than 90% after preoxygenation. Adverse hemodynamic tracheal intubation-associated event was defined as cardiac arrests, hypo or hypertension requiring intervention, and dysrhythmia.A total of 5,498 primary tracheal intubations from 31 ICUs were reported. Moderate desaturation was observed in 19.3% associated with adverse hemodynamic tracheal intubation-associated events (9.8% among children with moderate desaturation vs 4.4% without desaturation; p0.001). Severe desaturation was observed in 12.9% of tracheal intubations, also significantly associated with hemodynamic tracheal intubation-associated events. After adjusting for patient, provider, and practice factors, the occurrence of moderate desaturation was independently associated with hemodynamic tracheal intubation-associated events: adjusted odds ratio 1.83 (95% CI, 1.34-2.51; p0.001). The occurrence of severe desaturation was also independently associated with hemodynamic tracheal intubation-associated events: adjusted odds ratio 2.16 (95% CI, 1.54-3.04; p0.001). Number of tracheal intubation attempts was also significantly associated with the frequency of moderate and severe desaturations (p0.001).In this large tracheal intubation quality improvement database, we found moderate and severe desaturation are reported among 19% and 13% of all tracheal intubation encounters. Moderate and severe desaturations were independently associated with the occurrence of adverse hemodynamic events. Future quality improvement interventions may focus to reduce desaturation events.

Two-dimensional (2D) modeling is reported for InGaP/GaAs/InGaAs four-junction solar cell with tunnel junctions. The cell basic physical properties were demonstrated. The simulated results indicate one-sun efficiency about 40.1% with short-circuit current density as 126.63 A/m2 and open-circuit voltage as 3.69V. High efficiency up to 45.9% under 100 sun illumination could be achieved.

Objectives To investigate adaptive skills, behavior, and quality health-related quality of life in children from 32 centers enrolling in the Heart And Lung Failure-Pediatric INsulin Titration randomized controlled trial. Study design This prospective longitudinal cohort study compared the effect of 2 tight glycemic control ranges (lower target, 80-100 mg/dL vs higher target, 150-180 mg/dL) 1-year neurobehavioral and health-related quality of life outcomes. Subjects had confirmed hyperglycemia and cardiac and/or respiratory failure. Patients aged 2-16 years old enrolled between April 2012 and September 2016 were studied at 1 year after intensive care discharge. The primary outcome, adaptive skills, was assessed using the Vineland Adaptive Behavior Scale. Behavior and health-related quality of life outcomes were assessed as secondary outcomes using the Pediatric Quality of Life and Child Behavior Checklist at baseline and 1-year follow-up. Group differences were evaluated using regression models adjusting for age category, baseline overall performance, and risk of mortality. Results Of 369 eligible children, 358 survived after hospital discharge and 214 (60%) completed follow-up. One-year Vineland Adaptive Behavior Scale-II composite scores were not different (mean ± SD, 79.9 ± 25.5 vs 79.4 ± 26.9, lower vs higher target; P = .20). Improvement in Pediatric Quality of Life total health from baseline was greater in the higher target group (adjusted mean difference, 8.2; 95% CI, 1.1-15.3; P = .02). Conclusions One-year adaptive behavior in critically ill children with lower vs higher target glycemic control did not differ. The higher target group demonstrated improvement from baseline in overall health. This study affirms the lack of benefit of lower glucose targeting. Trial registration ClinicalTrials.gov : NCT01565941 .

To describe the treatment practices in critically ill children with RSV bronchiolitis across four regional PICUs in the northeastern United States, and to determine the factors associated with increased ICU length of stay in this population.We conducted a retrospective cohort study of children who were admitted with RSV bronchiolitis between July 2009 and July 2011 to the PICUs of Connecticut Children's Medical Center, Yale-New Haven Children's Hospital, Maria Fareri Children's Hospital, and Baystate Children's Hospital. Data were collected regarding clinical characteristics and intensive care course among these hospitals.During the study period, 323 children were admitted to one of the four ICUs with RSV bronchiolitis. Despite similar mortality risk scores among ICUs, there was considerable variation in the use of therapies, particularly intubation and mechanical ventilation, in which there was greater than a 3.5-fold increased risk of intubation between sites with the highest and lowest frequency of intubation (odds ratio: 3.8; 95% confidence interval: 2.2-6.4). Albuterol was the most commonly used respiratory treatment, followed by chest physiotherapy, high-flow nasal cannula, and hypertonic saline. Longer stays in the ICU were associated with more frequent use of therapies, specifically invasive mechanical ventilation, inhaled corticosteroids, intrapulmonary percussive ventilation, and chest physiotherapy.Even within a close geographic region, there is significant variation in the treatment provided to critically ill children with RSV bronchiolitis. None of these treatments were associated with shorter durations of hospitalization in this population and some, such as mechanical ventilation, were associated with longer ICU lengths of stay.

This paper proposes an eco-design method to suggest improvements over an existing diaphragm forming process (DFP). In the proposed method, a systematic procedure is developed to provide eco-design guidance to engineers, and it includes four steps. In Step 1, design functions are analysed through functional diagrams to provide the information of sub-functions and functional flows. In Step 2, the eco-design requirements are captured via quality functional deployment (QFD) and then translated to design functions via functional analysis (FA). Then, the design functions are prioritized according to the eco-design requirements in considerations. In Step 3, the prioritized design functions are used to generate possible design concepts through the morphological chart. In Step 4, the generated concepts are assessed based on the energy use and process time of DFP. The utility of the proposed method is to adapt quality tools for continual improvements in the context of eco-design. An existing DFP is used for...

Compared with consultative US performed by the radiology department, point-of-care US performed by non-radiology physicians can accurately diagnose deep venous thrombosis in adults. In preparation for a multicenter randomized controlled trial, we determined the accuracy of point-of-care US in diagnosing central venous catheter-related thrombosis in critically ill children. Children

The GaN-based light-emitting diodes (LEDs) with hemisphere patterned sapphire substrate (PSS) have been investigated numerically using a combined method of ray tracing and finite-difference time-domain techniques based on Poynting vector. Our method has been verified using unpatterned sapphire substrate for which analytical formulas exist. The simulated results show that the hemisphere PSS can improve the light extraction efficiency by increasing the reflection angle, decreasing the transmission angle, enhancing the reflectance of light incident on it, and enlarging the escape cone at its interface. Moreover, it is found that the hemisphere pattern size has significant influence on the improvement of the LED emission efficiency. The optimal radius of the hemisphere is about the emission wavelength of GaN-based LEDs, which can be attributed to the strong effect of wave properties of light at the PSS interface.

In this paper, a multiscale approach coupling semi-classical drift-diffusion (DD) and the quantum mechanical non-equilibrium Green’s function (NEGF) formalism is established to simulate the full geometry of miniaturized GaN high electron mobility transistors (HEMTs). DD current flow is corrected locally in the HEMT channel, where electron transport represented by the NEGF is governed by quantum effects. As a result, simulated drain current–drain voltage and drain current–gate voltage curves are easily fitted to experimental data without fitting mobility. The variation of electric behavior predicted by our multiscale approach is in agreement with that expected from 2D electrostatics. This work indicates that it is practical and efficient to include NEGF in a DD solver, which is still the workhorse of the technology computer-aided design industry.

Objective To determine the epidemiology of lower extremity deep venous thrombosis (DVT) in critically ill adolescents, which currently is unclear. Study design We performed a multicenter, prospective, cohort study. Adolescents aged 13-17 years who were admitted to 6 pediatric intensive care units and were anticipated to receive cardiopulmonary support for at least 48 hours were eligible, unless they were admitted with DVT or pulmonary embolism or were receiving or anticipated to receive therapeutic anticoagulation. While patients were in the unit, serial sonograms of the lower extremities were performed, then centrally adjudicated. Bayesian statistics were used to leverage the similarities between adults and adolescents. Results A total of 88 adolescents were enrolled, from whom 184 lower extremity sonograms were performed. Of these, 9 adolescents developed DVT, with 1 having bilateral DVT. The frequency of DVT was 12.4% (95% credible interval: 6.1%, 20.1%), which ranged from 6.3% to 19.8% with a variability of 41.0% across units. All cases of DVT occurred in adolescents who received invasive mechanical ventilation (frequency: 16.5%; 95% credible interval 8.1%, 26.6%). DVT was associated with femoral central venous catheterization (OR 15.44; 95% credible interval 1.62, 69.05) and severe illness (OR for every 0.1 increase in risk of mortality 3.11; 95% credible interval 1.19, 6.85). DVT appears to be associated with prolonged days on support. Conclusions Our findings highlight the similarities and differences in the epidemiology of DVT between adults and adolescents. They support the conduct and inform the design of a trial of pharmacologic prophylaxis in critically ill adolescents.

Optimized GaN-based light-emitting diodes (LEDs) were recently demonstrated to emit photons of higher energy than provided by the injected electrons up to elevated currents beyond the peak of the power conversion efficiency. Correspondingly, the electrical efficiency is above unity, which is attributed to heat extraction from the crystal lattice. In good agreement with measurements, we investigate the origin of such electroluminescent cooling by advanced numerical simulation including all relevant heat transfer mechanisms. For the first time, our simulations reveal the magnitude and the local profile of the heat extraction from the lattice. The built-in nitride polarization field is found to enhance the cooling effect significantly.

The natural circulation test (NCT) was conducted in the Phenix prototype French 580 MWth sodium fast reactor (SFR) in 2009. The main goal of the Phenix NCT is to validate system- and CFD-codes with respect to the establishment of natural circulation in the primary system of a pool type SFR. The present paper describes the calculation of the NCT by coupling the 3D computational fluid dynamics (CFD) code TRIO_U with the best estimate thermal hydraulic system code CATHARE. The coupling methodology and the modeling at the system and at the CFD scales are first presented. A validation of the coupling methodology based on a coupled CATHARE/CATHARE calculation compared to the standard CATHARE predictions is then proposed. In a second step, the results of the TRIO_U/CATHARE calculation are compared both to the available experimental data and to the results of a CATHARE alone computation. These comparisons highlight the effectiveness of coupling CFD- and system-codes for the analysis of plant transients where three-dimensional phenomena play an important role.

The stakes for the prevention of central line associated bloodstream infections (CLABSIs) have increased dramatically over the past decade. Over the past 10 years, the rate of CLABSI in the pediatric population has dropped markedly due to the significant investment in this initiative. Although there has been a substantial increase in studies on CLABSIs, difficulties in studying CLABSIs have limited the quality of the evidence produced. These difficulties include challenges in the sample size required to complete trials, pressure from external regulatory forces to reduce CLABSI rates, and challenges in defining CLABSIs. The definition of CLABSI is continuously being updated to improve the misclassification bias inherent in defining CLABSI. This is especially relevant given the stress placed on decreasing health-care-associated infections and the negative consequences associated if unsuccessful. In order to prevent CLABSIs, pediatric and neonatal intensive care units have formed bundles of basic evidenced-based strategies leading to effective reduction of CLABSIs. These basic bundles have been modified for spread to other nonintensive care areas, also yielding great results. However, additional therapies above the basic bundle have yielded mixed results, and more research is needed to understand the cost effectiveness of these therapies in the setting of decreasing CLABSI rates. As a goal, a "getting to zero" CLABSI rate should be set, but it may not be possible without significant resource allocation.

GaN-based multiple quantum well light-emitting diodes (LEDs) with the conventional, graded and two-step graded AlGaN last quantum barriers (LQBs) are investigated numerically. The simulation results show that the LED with two-step graded AlGaN LQB exhibits much higher light output power, lower turn-on voltage and smaller efficiency droop than those with the conventional and graded AlGaN LQBs. These improvements can be mainly attributed to the reduction of the electrostatic fields in the LQB and electron blocking layer caused by the mitigation of polarization effect with the redesigned LQB which enhances the electron confinement and improves the hole injection efficiency from p-type region greatly. Moreover, the two-step graded LQB not only improves the electron confinement of the EBL but also that of itself.

Despite significant advances in biological imaging and analysis, major informatics challenges remain unsolved: file formats are proprietary, storage and analysis facilities are lacking, as are standards for sharing image data and results. While the open FITS file format is ubiquitous in astronomy, astronomical imaging shares many challenges with biological imaging, including the need to share large image sets using secure, cross-platform APIs, and the need for scalable applications for processing and visualization. The Open Microscopy Environment (OME) is an open-source software framework developed to address these challenges. OME tools include: an open data model for multidimensional imaging (OME Data Model); an open file format (OME-TIFF) and library (Bio-Formats) enabling free access to images (5D+) written in more than 145 formats from many imaging domains, including FITS; and a data management server (OMERO). The Java-based OMERO client-server platform comprises an image metadata store, an image repository, visualization and analysis by remote access, allowing sharing and publishing of image data. OMERO provides a means to manage the data through a multi-platform API. OMERO’s model-based architecture has enabled its extension into a range of imaging domains, including light and electron microscopy, high content screening, digital pathology and recently into applications using non-image data from clinical and genomic studies. This is made possible using the Bio-Formats library. The current release includes a single mechanism for accessing image data of all types, regardless of original file format, via Java, C/C++ and Python and a variety of applications and environments (e.g. ImageJ, Matlab and R).

Recently, GaN-based light-emitting diodes (LEDs) were demonstrated to emit photons of higher energy than the injected electrons up to elevated currents, which is attributed to heat extraction from the crystal lattice. We investigate this electroluminescent cooling effect by advanced device simulation which is in good agreement with measurements on industry-grade blue LEDs. The built-in polarization is found to enhance the cooling process while Joule heating is negligible even at higher currents. Strategies for enhanced heat removal from the LED are evaluated.

Acute kidney injury (AKI) occurs commonly after pediatric cardiac surgery and associates with poor outcomes. Biomarkers may help the prediction or early identification of AKI, potentially increasing opportunities for therapeutic interventions. Here, we conducted a prospective, multicenter cohort study involving 311 children undergoing surgery for congenital cardiac lesions to evaluate whether early postoperative measures of urine IL-18, urine neutrophil gelatinase-associated lipocalin (NGAL), or plasma NGAL could identify which patients would develop AKI and other adverse outcomes. Urine IL-18 and urine and plasma NGAL levels peaked within 6 hours after surgery. Severe AKI, defined by dialysis or doubling in serum creatinine during hospital stay, occurred in 53 participants at a median of 2 days after surgery. The first postoperative urine IL-18 and urine NGAL levels strongly associated with severe AKI. After multivariable adjustment, the highest quintiles of urine IL-18 and urine NGAL associated with 6.9- and 4.1-fold higher odds of AKI, respectively, compared with the lowest quintiles. Elevated urine IL-18 and urine NGAL levels associated with longer hospital stay, longer intensive care unit stay, and duration of mechanical ventilation. The accuracy of urine IL-18 and urine NGAL for diagnosis of severe AKI was moderate, with areas under the curve of 0.72 and 0.71, respectively. The addition of these urine biomarkers improved risk prediction over clinical models alone as measured by net reclassification improvement and integrated discrimination improvement. In conclusion, urine IL-18 and urine NGAL, but not plasma NGAL, associate with subsequent AKI and poor outcomes among children undergoing cardiac surgery.

In this paper, we study the effect of polarization on the performance of InGaN solar cells. By using the APSYS software, we show that device performance is adversely affected due to the interface charges near GaN contact layers and that alternate means of creating ohmic contacts should be considered.

A multiple quantum well (MQW) transistor vertical-cavity surface- emitting laser (T-VCSEL) is designed and numerically modeled. The impor- tant physical models and parameters are discussed and validated by modeling a conventional VCSEL and comparing the results with the experiment. The quantum capture/escape process is simulated using the quantum-trap model and shows a signicant eect on the electrical output of the T-VCSEL. The parameters extracted from the numerical simulation are imported into the an- alytic modeling to predict the frequency response and simulate the large-signal modulation up to 40 Gbps.

Objectives The epidemiology of clinically relevant bleeding in critically ill adolescents, particularly those who are at high risk of venous thromboembolism, is unclear. In preparation for a randomized clinical trial of pharmacologic prophylaxis against venous thromboembolism, we characterized the epidemiology of clinically relevant bleeding in critically ill adolescents. Design Post hoc analysis of data from a pediatric multicenter observational study of venous thromboembolism. Setting Six PICUs. Patients Adolescents 13-17 years old who received cardiac or pulmonary support for at least 48 hours were eligible. Those admitted with venous thromboembolism or receiving therapeutic anticoagulation were excluded. Interventions None. Measurements and main results Adolescents (n = 88) were followed daily for the development of any bleeding event. The severity of the event was categorized based on the definitions by the International Society on Thrombosis and Haemostasis. The frequency of clinically relevant bleeding was 29.5% (95% CI, 20.3-40.2%) or 3.7 events (95% CI, 2.5-5.4 events) per 100 patient-days. Adolescents with venous thromboembolism were more likely to develop clinically relevant bleeding (hazard ratio, 2.06; 95% CI, 1.08-3.94). Age was negatively associated with clinically relevant bleeding (hazard ratio for every 1-year increase in age: 0.68; 95% CI, 0.58-0.79). In contrast, predicted risk of mortality (hazard ratio for every 0.10 increase in risk: 1.35; 95% CI, 1.05-1.74) and admission for trauma or surgery (hazard ratio: 2.04; 95% CI, 1.21-3.44) were positively associated with clinically relevant bleeding. The association of clinically relevant bleeding with medications, interventions, or laboratory tests, including mechanical ventilation and pharmacologic prophylaxis with anticoagulation, did not reach statistical significance. Adolescents with clinically relevant bleeding stayed in the hospital longer than those without clinically relevant bleeding. Conclusions Clinically relevant bleeding is common in critically ill adolescents who are at high risk of venous thromboembolism. Admission for trauma or surgery can be used to stratify the risk of clinically relevant bleeding in these adolescents.

Nitride-based light-emitting diodes suffer from a reduction (droop) of the internal quantum efficiency (IQE) with increasing injection current. Using advanced device simulation, we investigate the impact of electron leakage on the IQE droop for different properties of the electron blocker layer (EBL). The simulations show a strong influence of the EBL acceptor density on the droop. We also find that the electron leakage decreases with increasing temperature, which contradicts common assumptions.

This paper describes a bidirectional, differential, 16 Gb/s per link memory interface that includes a Controller and an emulated DRAM physical interface (PHY) designed in 65 nm CMOS. To achieve high data rate, the interface employs the following technology ingredients: asymmetric equalization, asymmetric timing calibration, asymmetric link margining, inductor based (LC) PLLs, multi-phase error correction, and a data dependent regulator. At 16 Gb/s, this interface achieves a unit-interval to inverter FO4 ratio of 2.8 (Controller) and 1.4 (DRAM) and operates in a channel with 15 dB loss at Nyquist. Under such bandwidth limitations on and off chip, the Controller and DRAM PHYs consume 13 mW/Gb/s and 8 mW/Gb/s, respectively. Using PRBS 211-1, the link achieves a timing margin of 0.19 UI at a BER of 1e-12 for both read and write operations.

In this work, based on the advanced drift and diffusion model with commercial software, the Crosslight APSYS, InP/InGaAs separate absorption, grading, charge and multiplication APDs for high bit-rate operation have been modeled. Basic physical quantities such as band diagram, optical absorption and generation are calculated. Performance characteristics such as dark- and photo-current, photoresponsivity, multiplication gain, breakdown voltage, excess noise, frequency response and bandwidth etc., are simulated. The modeling results are selectively presented, analyzed, and some results are compared with experiments. Device design optimization issues are further discussed with respect to the applicable features of the Crosslight APSYS within the framework of the drift-diffusion theory. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In this work, two-dimensional simulation has been performed on the triple-junction (TJ) GaInP/GaAs/Ge solar cell devices based on the Crosslight APSYS with improved tunnel junction model. The APSYS simulator solves several interwoven equations including the basic Poisson's equation, and drift-diffusion current equations for electrons and holes. Basic physical quantities like band diagrams, optical absorption and generation are calculated. The simulated IV characteristics and offset voltage agree well with the published experimental results for TJ GaInP/GaAs/Ge solar cell device. The quantum efficiency spectra have also been computed. Possible design optimization issues to enhance the quantum efficiency have also been discussed with respect to some applicable features of Crosslight APSYS. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We report on the 2D simulations of electrical and optical characteristics for green color InGaN/GaN multiple quantum well light-emitting diodes by the APSYS software. The In-rich quantum dot-like structure in InGaN/GaN multiple quantum wells has been considered with quantum dot model. The simulation results are in good agreement with experiment and indicate that quantum dot spontaneous emission and non-equilibrium quantum transport play an important role in the InGaN/GaN multiple quantum well light-emitting diodes.

This paper presents a formal two-phase decomposition method for complex design problems that are represented in an attribute-component incidence matrix. Unlike the conventional approaches, this method decouples the overall decomposition process into two separate, autonomous function components: dependency analysis and matrix partitioning, which are algorithmically achieved by an extended Hierarchical Cluster Analysis (HCA) and a Partition Point Analysis (PPA), respectively. The extended HCA (Phase 1) is applied to convert the (input) incidence matrix, which is originally unorganized, into a banded diagonal matrix. The PPA (Phase 2) is applied to further transform this matrix into a block-angular matrix according to a given set of decomposition criteria. This method provides both flexibility in the choice of the different settings on the decomposition criteria, and diversity in the generation of the decomposition solutions, both taking place in Phase 2 without resort to Phase 1. These features essentially make this decomposition method effective, especially in its application to re-decomposition. A powertrain design example is employed for illustration and discussion.

Simulations of the characteristics of laser diodes (LD) with non-polar and InGaN multi-quantum-wells (MQW) have been conducted in multi-dimensional drift-diffusion model. The strain coefficients of the QWs of arbitrary crystal-orientations are obtained by minimizing the total strain energy. Electronic structure and optical gain of non-polar InGaN QWs are calculated by the 6x6 k.p theory. Finally by integrating the gain and effective mass models of non-polar InGaN QW into our LASTIP software package, we simulated the performance of the laser diodes with non-polar MQWs, and the results are compared with the experiments. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Comprehensive electro-opto and thermal analysis on GaSb-based vertical-cavity surface-emitting lasers (VCSELs) emitting at 2.6μm are presented. The theoretical models include a 2D/3D drift-diffusion equations for carrier transport coupled with the optical model which describes the spontaneous noise as the driving force for lasing. Optical gain is obtained by Fermi’s golden rule and the self-consistent solution of Schrodinger equation. Self- heating effects of the device are also included self-consistently. These results shed light on the internal device physics such as carrier transport, temperature ditribution, optical gain and losses etc. Based on the simulation, we also discuss the areas for future improvements.

We report on a 2D simulation study of a couple of mid-infrared quantum cascade lasers based on the integration of a number of optoelectronic models. Quantum mechanical computation was performed to find the quantization states and a rate equation approach was used to compute the optical gain. Temperature and field dependence effects are taken into account in optical gain model to make a realistic simulation of QCLs. The simulation study compared the integrated models with experimental data with different structures and at different temperatures. Reasonable agreements between experiment and simulation have been obtained.

Blue InGaN/GaN multiple quantum well (MQW) light-emitting diodes (LEDs) with patterned sapphire substrate (PSS) are simulated by the APSYS software. Approach of combining finite-difference time-domain (FDTD) method and ray tracing technique is applied to perform light extraction. The simulation results show that PSS dramatically increases extraction efficiency of light power, in agreement with experiment. It is found that extraction efficiency can be maximized by changing the shape of PSS. This work presents a new approach to combine electrical simulation with FDTD and raytracing for both accuracy and efficiency in 3D TCAD simulation of GaN-LED.

Blue InGaN/GaN multiple quantum well (MQW) light-emitting diodes (LEDs) are simulated by the APSYS software with a non-local quantum well transport model which is used to describe the phenomenon that carriers can fly over the quantum wells directly. The simulation results based on this model are in good agreement with the experiment and show its significant influence on the output power, carrier transport, peak wavelength and current crowding effect of the InGaN/GaN MQW LEDs, indicating that the non-local quantum well transport plays an important role in these devices.

Objective To determined the current incidence and acute complications of asymptomatic central venous catheter (CVC)-related deep venous thrombosis (DVT) in critically ill children. Study design We performed a prospective cohort study in 3 pediatric intensive care units. A total of 101 children with newly inserted untunneled CVC were included. CVC-related DVT was diagnosed using compression ultrasonography with color Doppler. Results Asymptomatic CVC-related DVT was diagnosed in 16 (15.8%) children, which equated to 24.7 cases per 1000 CVC-days. Age was independently associated with DVT. Compared with children aged 13 years had significantly higher odds of DVT (aOR, 14.1, 95% CI, 1.9-105.8; P = .01). Other patient demographics, interventions (including anticoagulant use), and CVC characteristics did not differ between children with and without DVT. Mortality-adjusted duration of mechanical ventilation, a surrogate for pulmonary embolism, was statistically similar in the 2 groups (22 ± 9 days in children with DVT vs 23 ± 7 days in children without DVT; P = .34). Mortality-adjusted intensive care unit and hospital lengths of stay also were similar in the 2 groups. Conclusion Asymptomatic CVC-related DVT is common in critically ill children. However, the acute complications do not seem to differ between children with and without DVT. Larger studies are needed to confirm these results. Future studies should also investigate the chronic complications of asymptomatic CVC-related DVT.

We report a simulation study of carrier transport in quantum cascade lasers (QCLs) based on non-local transport model. In this model, drift-diffusion equations are solved with modification of current density by accounting for long-range carrier transport including quantum tunneling and hot carrier transport in the device. From the simulation results of an AlInGaAs/InP QCL at different temperatures, it is found that our model shows reasonable agreement with experiments at lower temperature when carriers are well confined while substantial deviation is observed at higher temperatures when the leakage of carriers into the continuum is significant.

As silicon transistors get smaller and faster, the bottleneck of the IC boils down to interconnects which traditionally use copper or aluminum wires with limited speed and bandwidth. Silicon-based optoelectronic integration offers the promise of low-cost solutions for optical communications and interconnects. A major advance in this field is the use of III–V lasers bonded on silicon and coupled to silicon waveguides. Such an approach is called hybrid integration and lasers built using such this approach are called hybrid silicon lasers.

To get the reader familiarize with 3D TCAD simulation, we start with the simplest p-n junction diode imaginable. This diode has just one mask layer as shown in Fig. 5.1. Strictly speaking, this simulation example is just an extension of a 2D problem since there is no variation in the z direction; it could even be modeled in 1D. Nevertheless, this is a good place to start.

Using Crosslight APSYS, we have made two-dimensional simulation of triple junction solar cells based on the CdZnTe/CdTe/Si material system with tunnel junctions. The basic physical quantities like band diagram, optical absorption and generation for the modeled TJ cell, and external quantum efficiency for individual sub cell junctions are obtained. Current matching analyses and multi-sun concentration simulation are performed and the presented results indicate cell efficiency 34.92% (one sun) and maximum 39.09% (around 500–700 sun). The results indicates that II-VI CdZnTe and CdTe based materials can be used to develop multi-junction solar cell on silicon substrate with cell efficiency comparable to those III-V based compound on Ge substrate.

In this multicenter, prospective study of 288 children (half under 2 years of age) undergoing cardiac surgery, we evaluated whether the measurement of pre- and postoperative serum cystatin C (CysC) improves the prediction of acute kidney injury (AKI) over that obtained by serum creatinine (SCr). Higher preoperative SCr-based estimated glomerular filtration rates predicted higher risk of the postoperative primary outcomes of stage 1 and 2 AKI (adjusted odds ratios (ORs) 1.5 and 1.9, respectively). Preoperative CysC was not associated with AKI. The highest quintile of postoperative (within 6 h) CysC predicted stage 1 and 2 AKI (adjusted ORs of 6 and 17.2, respectively). The highest tertile of percent change in CysC independently predicted AKI, whereas the highest tertile of SCr predicted stage 1 but not stage 2 AKI. Postoperative CysC levels independently predicted longer duration of ventilation and intensive care unit length of stay, whereas the postoperative SCr change only predicted longer intensive care unit stay. Thus, postoperative serum CysC is useful to risk-stratify patients for AKI treatment trials. More research, however, is needed to understand the relation between preoperative renal function and the risk of AKI.

GaN-based vertical-cavity surface-emitting lasers (VCSELs) are expected to exhibit several advantages over their already widely used edge-emitting counterparts, including lower manufacturing costs, circular output beams, and longer lifetime. However, in contrast to the great success of GaN-based edge-emitting lasers in recent years, GaN-VCSELs still face significant challenges. Electrically pumped devices have been demonstrated only recently and they exhibit severe performance restrictions. We here analyze these recently manufactured GaN-VCSELs using advanced laser simulation software. The simulation self-consistently combines carrier transport, photon emission, and multi-mode optical wave guiding. For the quantum wells, Schrodinger and Poisson equations are solved iteratively at every bias point to account for the Quantum-Confined Stark Effect. Our analysis shows that thick quantum wells allow for the almost complete elimination of the built-in quantum well polarization field. The simulations also reveal several performance limiting effects, e.g., gain-peak offset, current crowding, and electron leakage. Design optimization options are discussed and simulated.

Two-dimensional modeling has been performed on silicon rear-contacted solar cells with laser-fired contact and surface triangle texture by using Crosslight APSYS and CSUPREM. Laser firing is simulated with local heating and aluminum diffusion, and surface texture effect is simulated with ray tracing. It is shown that the cell efficiency can be improved by increasing the concentration of aluminum clusters and the lasing time with the laser firing process. The results are further analyzed with dark current and built-in potential. The surface texture also improves the cell efficiency with enhanced optic absorption. The effect of high lasing power intensity is also discussed.

Crystalline silicon solar cells with laser-fired contact (LFC) are simulated with Crosslight APSYS and CSUPREM. Different laser firing parameters lead to different LFC profiles and different cell performances. It is shown that the cell efficiency can be improved to a relatively stable value by increasing concentration of aluminum clusters, lasing time or laser spot diameter. The results are further explained quantitatively by dark current and qualitatively by built-in potential.

In this work, based on the advanced drift and diffusion model with commercial software, the Crosslight APSYS, twodimensional photoresponsivity behavior for the InP/InGaAs separate absorption, grading, charge and multiplication avalanche photodiodes have been modeled to analyze suppressing premature edge breakdown. Basic physical quantities like band diagram, photon absorption, carrier generation and electric field as well as performance characteristics such as photocurrent, multiplication gain, and breakdown voltage etc., are obtained and selectively presented. Modeling results indicate that an etched mesa structure with the charge sheet layer can effectively suppress the premature edge breakdown in the device periphery region. Optimization modeling results with mesa step height are also demonstrated. Approach to model complex guard ring structure with double diffusion is further explored. Possible combination of Crosslight CSuprem diffusion profile is also discussed.

Two-dimensional (2D) simulation has been performed on the inverted metamorphic GaInP/GaAs/InGaAs triple-junction (TJ) solar cells based on the Crosslight APSYS with improved tunnel junction model. The APSYS simulator solves semiconductor drift-diffusion equations by finite-element method. Optic propagation in solar cell device is modeled with transfer matrix method and/or ray tracing. The carrier photo-generation is calculated using experimental absorption coefficients. SRH, Auger, radiative and surface/interface recombination are all taken into account. The 2D simulation gives detailed information on the band diagram, optical power absorption and carrier transport etc. The simulated results of one-sun I–V curve with V oc , I sc and efficiency are in good agreement with the experimental. The results are further discussed with respect to current matching, multi-sun concentration and the top contact grid spacing.

Avalanche photodiodes (APDs) are being widely utilized in various application fields where a compact technology computer aided design (TCAD) kit capable for APD modeling is highly demanded. In this work, based on the advanced drift and diffusion model with commercial software, the Crosslight APSYS, avalanche photodiodes, especially the InP/InGaAs separate absorption, grading, charge and multiplication (SAGCM) APDs for high bit-rate operation have been modeled. Basic physical quantities like band diagram, optical absorption and generation are calculated. Performance characteristics such as dark- and photo-current, photoresponsivity/multiplication gain, breakdown voltage, excess noise, frequency response and bandwidth etc., are simulated. The modeling results are selectively presented, analyzed, and some of results are compared with the experimental. Device design optimization issues are further discussed with respect to the applicable features of the Crosslight APSYS within the framework of drift-diffusion theory.

In this work, based on the advanced commercial software, the Crosslight APSYS with improved tunnel junction model, two-dimensional (2D) simulation has been performed on the triple-junction (TJ) GaInP/GaAs/Ge solar cell devices. The APSYS simulator solves several interwoven equations including the basic Poisson's equation, and drift-diffusion current equations for electrons and holes. The model of tunnel junction with the equivalent mobility enables an efficient modeling of multi-junction solar cell across the whole solar spectra, where all the spectrum data points are processed by taking into account the effects of multiple layer optical interference and photon generation. Basic physical quantities like band diagrams, optical absorption and generation are demonstrated. The modeled IV characteristics and offset voltage agree well with the published experimental results for TJ GaInP/GaAs/Ge solar cell device. The quantum efficiency spectra have also been computed for the modeled TJ solar cell device. Possible design optimization issues to enhance the quantum efficiency have also been discussed with respect to some applicable features of Crosslight APSYS.