Objective
To study the effect of delivery on the pO2/FiO2 ratio (P/F ratio) in patients with COVID‐19‐related acute respiratory distress syndrome (ARDS) and to compare characteristics between ...delivered and undelivered pregnant patients with COVID‐19.
Design
Retrospective cohort.
Setting
Four hospitals in Houston, Texas.
Population
Pregnant patients admitted to the hospital for COVID‐19.
Methods
Among patients with ARDS who were delivered during their hospitalisation for COVID‐19, linear mixed models were used to investigate time trends before and after delivery of the P/F ratio. Patient characteristics were compared between patients delivered during their hospitalisation for COVID‐19 and those discharged undelivered.
Main outcome measures
The P/F ratio, age, gestational age, length of stay and severity of illness,
Results
Between 4 May 2020 and 26 July 2020, a total of 61 pregnant patients were admitted for COVID‐19. Baseline characteristics were similar between the study groups. Delivery occurred in 21 (34%) of patients during their hospitalisation for COVID‐19. Delivered patients had more severe disease and were admitted at a later gestational age than patients not delivered. Ten of these 21 patients (48%) were delivered preterm; of these, six were delivered due to complications of COVID‐19 and four were delivered for obstetric indications. In patients with ARDS who were delivered (n = 17), the P/F ratio had a negative slope that improved after delivery.
Conclusions
COVID‐19‐related ARDS in pregnancy requires multidisciplinary care and individualised decision‐making, but delivery slows the deterioration of the P/F ratio in these patients.
Tweetable
Delivery improves the P/F ratio in COVID‐19‐related ARDS, though individualised delivery management is needed.
Tweetable
Delivery improves the P/F ratio in COVID‐19‐related ARDS, though individualised delivery management is needed.
To study the effect of delivery on the pO
/FiO
ratio (P/F ratio) in patients with COVID-19-related acute respiratory distress syndrome (ARDS) and to compare characteristics between delivered and ...undelivered pregnant patients with COVID-19.
Retrospective cohort.
Four hospitals in Houston, Texas.
Pregnant patients admitted to the hospital for COVID-19.
Among patients with ARDS who were delivered during their hospitalisation for COVID-19, linear mixed models were used to investigate time trends before and after delivery of the P/F ratio. Patient characteristics were compared between patients delivered during their hospitalisation for COVID-19 and those discharged undelivered.
The P/F ratio, age, gestational age, length of stay and severity of illness, RESULTS: Between 4 May 2020 and 26 July 2020, a total of 61 pregnant patients were admitted for COVID-19. Baseline characteristics were similar between the study groups. Delivery occurred in 21 (34%) of patients during their hospitalisation for COVID-19. Delivered patients had more severe disease and were admitted at a later gestational age than patients not delivered. Ten of these 21 patients (48%) were delivered preterm; of these, six were delivered due to complications of COVID-19 and four were delivered for obstetric indications. In patients with ARDS who were delivered (n = 17), the P/F ratio had a negative slope that improved after delivery.
COVID-19-related ARDS in pregnancy requires multidisciplinary care and individualised decision-making, but delivery slows the deterioration of the P/F ratio in these patients.
Delivery improves the P/F ratio in COVID-19-related ARDS, though individualised delivery management is needed.
The Legacy of Cornell Accelerators Tigner, M; Cassel, D.G
Annual review of nuclear and particle science,
10/2015, Letnik:
65, Številka:
1
Journal Article
Recenzirano
Odprti dostop
This is the story of a culture and its evolution and legacy. Beginning with the invention of the cyclotron at Berkeley, the path of further accelerator development at Cornell via the Los Alamos ...experience of the primary actors is described. The science done with the accelerators and on the accelerators and beams themselves is reviewed and brought up to the current time. The evolution of the user community and the sources of support for accelerators and science done with them are discussed at the appropriate places in the story.
One solution to minimizing plastic pollution is to improve reuse and recycling strategies. Recycling, however, is limited by the overall degradation of plastics being used, and current techniques for ...monitoring this plastic degradation fail to observe this in its early stages, which is key for optimizing reusability. This research seeks to develop an inexpensive, reproducible, and nondestructive technique for monitoring degradation of polyethylene (PE) and polypropylene (PP) materials using Nile red as a fluorescent probe. Changes in Nile red’s fluorescence spectra were observed upon exposure to stained, aged PE and PP samples. As the surface hydrophobicity of the plastic decreases, Nile red’s fluorescence signal undergoes a corresponding signal shift to longer wavelengths (lower energy). The trends seen in the fluorescent profile were related to more commonly used measurements of plastic degradation, namely, the carbonyl index from infrared spectroscopy and bulk crystallinity from calorimetry. Results demonstrate clear trends in fluorescence spectra shifts as related to the chemical and physical changes to the plastics, with trends dependent on the polymer type but independent of polymer film thickness. The strength of this technique is divided into two defined fits of the fluorescence signal; one fit characterizes the degradation throughout the whole range of degradative oxidation and the other is tailored to provide insight into the early stages of degradation. Overall, this work establishes a characterization tool that assesses the extent of plastics’ degradation, which may ultimately impact our ability to recover plastics and minimize plastic waste.
Ceramic nanocomposites of alumina and carbon nanotubes (CNTs) are experimentally studied for use as microwave absorbers in particle accelerators. The weight percentage of multi-walled CNTs in SPS ...sintered nanocomposite samples is varied from 0.5 to 10% and the complex permittivity is measured. The RF absorption is strong and relatively flat in the frequency band 1–40GHz for a CNT weight percentage in the range 1–2.5%, which is just above the percolation threshold. The permittivity is observed to increase dramatically with increasing CNT weight percentage above the percolation threshold as observed elsewhere, and in accordance with theoretical treatments. The electromagnetic properties of the nanocomposites are little changed in going from 294K to 77K. The DC conductivity of the alumina-CNT nanocomposite is also sufficient to drain static charge in particle accelerator beamline environments, even at cryogenic temperatures. Fabrication of the nanocomposites using an industrial RF sintering process compatible with large sizes shows that the microwave absorption properties of small samples are similar to those of the SPS sintered samples.
Superconducting TESLA cavities Aune, B.; Bandelmann, R.; Bloess, D. ...
Physical review special topics. Accelerators and beams,
09/2000, Letnik:
3, Številka:
9
Journal Article
Recenzirano
Odprti dostop
The conceptional design of the proposed linear electron-positron collider TESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with an accelerating gradient of Eacc≥25MV/m at a quality ...factor Q0≥5×109 . The design goal for the cavities of the TESLA Test Facility (TTF) linac was set to the more moderate value of Eacc≥15MV/m . In a first series of 27 industrially produced TTF cavities the average gradient at Q0=5×109 was measured to be 20.1±6.2MV/m , excluding a few cavities suffering from serious fabrication or material defects. In the second production of 24 TTF cavities, additional quality control measures were introduced, in particular, an eddy-current scan to eliminate niobium sheets with foreign material inclusions and stringent prescriptions for carrying out the electron-beam welds. The average gradient of these cavities at Q0=5×109 amounts to 25.0±3.2MV/m with the exception of one cavity suffering from a weld defect. Hence only a moderate improvement in production and preparation techniques will be needed to meet the ambitious TESLA goal with an adequate safety margin. In this paper we present a detailed description of the design, fabrication, and preparation of the TESLA Test Facility cavities and their associated components and report on cavity performance in test cryostats and with electron beam in the TTF linac. The ongoing research and development towards higher gradients is briefly addressed.
Future particle accelerators will require continuous wave operation of SRF cavities capable of supporting high beam currents. An example of this is the Energy Recovery Linac (ERL) at Cornell ...University, a next generation light source designed to run high currents (100mA) with a high bunch repetition rate (1.3GHz). Obtaining the beam emittance necessary to meet design specification requires strong damping of higher-order modes that can lead to beam breakup. We discuss the optimization and verification of the accelerating cavity. Next we show that an ERL constructed from the optimized cavity geometry – including realistic shape errors – can support beam currents in excess of 300mA while still maintaining beam stability. A niobium prototype 7-cell cavity was fabricated and tested in a horizontal cryomodule. We show that the prototype cavity exceeds quality factor and gradient specifications of 2×1010 at 16.2MV/m at 1.8K by 50%, reaching Q=(3.0±0.3)×1010. The prototype cavity also satisfies all design constraints and has a higher order mode spectrum consistent with the optimized shape geometry. At 1.6K, the cavity set a record for quality factor of a multicell cavity installed in a horizontal cryomodule reaching Q=(6.1±0.6)×1010.
Summary of Working Group 5 at NuFact’00 Tigner, M
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2001, Letnik:
472, Številka:
3
Journal Article
Recenzirano
R&D plans and efforts around the world are summarized. Some results of basic measurements are given and plans for more reviewed. Suggestions for test facilities and ionization cooling demonstrations ...are reviewed as are a number of hardware development activities aimed at particular needs of a neutrino factory.
Edited by internationally recognized authorities in the field, this expanded edition of the bestselling Handbook first published in 1999 is aimed at the design and operation of modern accelerators ...including Linacs, Synchrotrons and Storage Rings. It is intended as a vade mecum for professional engineers and physicists engaged in these subjects. With a collection of 2200 equations, 345 illustrations and 185 tables, here one will find, in addition to the common formulae of previous compilations, hard to find, specialized formulae, recipes and material data pooled from the lifetime experience of many of the world's most able practitioners of the art and science of accelerators.The eight chapters include both theoretical and practical matters as well as an extensive glossary of accelerator types. Chapters on beam dynamics and electromagnetic and nuclear interactions deals with linear and nonlinear single particle and collective effects including spin motion, beam-environment, beam-beam and intrabeam interactions. The impedance concept and calculations are dealt with at length as are the instabilities associated with the various interactions mentioned. A chapter on operational considerations deals with orbit error assessment and correction. Chapters on mechanical and electrical considerations present material data and important aspects of component design including heat transfer and refrigeration. Hardware systems for particle sources, feedback systems, confinement and acceleration (both normal conducting and superconducting) receive detailed treatment in a subsystems chapter, beam measurement techniques and apparatus being treated therein as well. The closing chapter gives data and methods for radiation protection computations as well as much data on radiation damage to various materials and devices.A detailed index is provided together with reliable references to the literature where the most detailed information available on all subjects treated can be found.
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