Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Comparison of isoprene chemical mechanisms under atmospheric night-time conditions in chamber experiments : Evidence of hydroperoxy aldehydes and epoxy products from NO3 oxidation

The gas-phase reaction of isoprene with the nitrate radical (NO3) was investigated in experiments in the outdoor SAPHIR chamber under atmospherically relevant conditions specifically with respect to the chemical lifetime and fate of nitrato-organic peroxy radicals (RO2). Observations of organic products were compared to concentrations expected from different chemical mechanisms: (1) the Master Chemical Mechanism, which simplifies the NO3 isoprene chemistry by only considering one RO2 isomer; (2) the chemical mechanism derived from experiments in the Caltech chamber, which considers different RO2 isomers; and (3) the FZJ-NO3 isoprene mechanism derived from quantum chemical calculations, which in addition to the Caltech mechanism includes equilibrium reactions of RO2 isomers, unimolecular reactions of nitrate RO2 radicals and epoxidation reactions of nitrate alkoxy radicals. Measurements using mass spectrometer instruments give evidence that the new reactions pathways predicted by quantum chemical calculations play a role in the NO3 oxidation of isoprene. Hydroperoxy aldehyde (HPALD) species, which are specific to unimolecular reactions of nitrate RO2, were detected even in the presence of an OH scavenger, excluding the possibility that concurrent oxidation by hydroxyl radicals (OH) is responsible for their formation. In addition, ion signals at masses that can be attributed to epoxy compounds, which are specific to the epoxidation reaction of nitrate alkoxy radicals, were detected. Measurements of methyl vinyl ketone (MVK) and methacrolein (MACR) concentrations confirm that the decomposition of nitrate alkoxy radicals implemented in the Caltech mechanism cannot compete with the ring-closure reactions predicted by quantum chemical calculations. The validity of the FZJ-NO3 isoprene mechanism is further supported by a good agreement between measured and simulated hydroxyl radical (OH) reactivity. Nevertheless, the FZJ-NO3 isoprene mechanism needs further investigations with respect to the absolute importance of unimolecular reactions of nitrate RO2 and epoxidation reactions of nitrate alkoxy radicals. Absolute concentrations of specific organic nitrates such as nitrate hydroperoxides would be required to experimentally determine product yields and branching ratios of reactions but could not be measured in the chamber experiments due to the lack of calibration standards for these compounds. The temporal evolution of mass traces attributed to product species such as nitrate hydroperoxides, nitrate carbonyl and nitrate alcohols as well as hydroperoxy aldehydes observed by the mass spectrometer instruments demonstrates that further oxidation by the nitrate radical and ozone at atmospheric concentrations is small on the timescale of one night (12gh) for typical oxidant concentrations. However, oxidation by hydroxyl radicals present at night and potentially also produced from the decomposition of nitrate alkoxy radicals can contribute to their nocturnal chemical loss

A Four Carbon Organonitrate as a Significant Product of Secondary Isoprene Chemistry

Abstract Oxidation of isoprene by nitrate radicals (NO3) or by hydroxyl radicals (OH) under high NOx conditions forms a substantial amount of organonitrates (ONs). ONs impact NOx concentrations and consequently ozone formation while also contributing to secondary organic aerosol. Here we show that the ONs with the chemical formula C4H7NO5 are a significant fraction of isoprene-derived ONs, based on chamber experiments and ambient measurements from different sites around the globe. From chamber experiments we found that C4H7NO5 isomers contribute 5%?17% of all measured ONs formed during nighttime and constitute more than 40% of the measured ONs after further daytime oxidation. In ambient measurements C4H7NO5 isomers usually dominate both nighttime and daytime, implying a long residence time compared to C5 ONs which are removed more rapidly. We propose potential nighttime sources and secondary formation pathways, and test them using a box model with an updated isoprene oxidation scheme

Reliability Analysis of Ethernet-Based Solutions for Data Transmission in the CERN Radiation Environment

The necessity for a radiation-tolerant communication link, compatible with a wide range of devices, has prompted the study of different solutions than those currently employed at CERN. With Ethernet being one of the most established communication protocols for commercial and industrial applications, most of the efforts were concentrated toward that direction. To evaluate the feasibility of using this protocol in the radiation environment of CERN, several Ethernet-based solutions have been implemented based on a system on chip (SoC), in which a flash-based field-programmable gate array (FPGA) and a $\mu$ controller coexist, making the system highly configurable. The proposed solutions are qualified at the system level using accelerated testing means, in order to compare their performances. The results of this study are then used to estimate the reliability of the different solutions using classic models, considering a variety of different installation scenarios inside the Large Hadron Collider (LHC) tunnel

Optimal and suboptimal control of anaerobic digesters

Anaerobic digester failure due to entry of inhibitors or sudden changes in the feed substrate concentration may be encompassed beneficially by applying optimal control theory. An almost proportional relationship between the dilution rate and the methane production rate leads to a simple suboptimal control law with only minor loss in performance, after the occurrence of the above mentioned events

Reliability analysis of a 65nm Rad-Hard SRAM-Based FPGA for CERN applications

In search of alternative solutions for Field Programmable Gate Arrays (FPGA) that can withstand the higher dose levels foreseen in the upcoming upgrades of the Large Hadron Collider (LHC), a new Radiation Hardened FPGA is targeted. More specifically, in this work, the effects of proton induced radiation on a 65nm Rad Hard SRAM-Based FPGA are investigated, while applying tailored tests for each resource of the FPGA. The results of the study are then used to perform a Reliability analysis of this device, adapted to the CERN radiation environment while using standard models

Analyzing the impact of radiation-induced failures in flash-based APSoC with and without fault tolerance techniques at CERN environment

All Programmable System-on-Chip (APSoC) devices are designed to provide higher overall programmable flexibility and system performance at lower costs. Such characteristics make APSoCs very suitable and attractive for critical environments, such as the one encountered in the accelerators chain of the European Organization for Nuclear Research (CERN), where electronic components can be exposed to high-energy hadrons (protons, neutrons, pions), heavy ions, and other particles, at the same time. However, APSoCs may be prone to experience Single Event Effects (SEE). We investigate how the configuration of the Processing System (PS) influences the reliability of a FLASH-based APSoC. We experimentally study the differences in the radiation-induced error rate of the PS, under various configurations while executing an application. We also propose two approaches for increasing the reliability of programs running on the embedded processor. Furthermore, we analyze the sensitivity of the system taking into account not only the cross section, but also the system reliability and the Mean Workload Between Failures (MWBF). Preliminary results show that it is possible to double the performance and to increase the system reliability up to one order of magnitude by managing processor features such as cache memory usage, error correcting codes, and processor exception handlers

Radiation Effects on Deep Submicrometer SRAM-based FPGAs under the CERN Mixed-Field Radiation Environment

In this paper, the single-event effects on a 28-nm static random access memory-based field-programmable gate array (FPGA) under CERN’s mixed-particle field are analyzed. The methodology followed for CERN electronics radiation hard- ness assurance and the particularities of testing an FPGA under a mixed-particle field are demonstrated. More specifically, the potential contribution of low-energy particles to the configuration memory (CRAM) and block memory (BRAM) bit upset sensitivity is investigated. By using a method of irradiating the device in different locations at CERN high-energy accelerator mixed field/facility with different particle energy spectra, it has been found that there is a significant impact of thermal neutrons, increasing the CRAM and BRAM cross section by a factor of ×3. As a complement to this paper, an example application is also tested, in the context of future upgrades at the CERN accelerator complex. Results estimate that the application fails less than 10 times per year, leading to the conclusion that such devices may be used for low criticality applications along the accelerator complex