CONTEXT Trials comparing higher vs lower levels of positive end-expiratory pressure (PEEP) in adults with acute lung injury or acute respiratory distress syndrome (ARDS) have been underpowered to ...detect small but potentially important effects on mortality or to explore subgroup differences. OBJECTIVES To evaluate the association of higher vs lower PEEP with patient-important outcomes in adults with acute lung injury or ARDS who are receiving ventilation with low tidal volumes and to investigate whether these associations differ across prespecified subgroups. DATA SOURCES Search of MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (1996-January 2010) plus a hand search of conference proceedings (2004-January 2010). STUDY SELECTION Two reviewers independently screened articles to identify studies randomly assigning adults with acute lung injury or ARDS to treatment with higher vs lower PEEP (with low tidal volume ventilation) and also reporting mortality. DATA EXTRACTION Data from 2299 individual patients in 3 trials were analyzed using uniform outcome definitions. Prespecified effect modifiers were tested using multivariable hierarchical regression, adjusting for important prognostic factors and clustering effects. RESULTS There were 374 hospital deaths in 1136 patients (32.9%) assigned to treatment with higher PEEP and 409 hospital deaths in 1163 patients (35.2%) assigned to lower PEEP (adjusted relative risk RR, 0.94; 95% confidence interval CI, 0.86-1.04; P = .25). Treatment effects varied with the presence or absence of ARDS, defined by a value of 200 mm Hg or less for the ratio of partial pressure of oxygen to fraction of inspired oxygen concentration (P = .02 for interaction). In patients with ARDS (n = 1892), there were 324 hospital deaths (34.1%) in the higher PEEP group and 368 (39.1%) in the lower PEEP group (adjusted RR, 0.90; 95% CI, 0.81-1.00; P = .049); in patients without ARDS (n = 404), there were 50 hospital deaths (27.2%) in the higher PEEP group and 44 (19.4%) in the lower PEEP group (adjusted RR, 1.37; 95% CI, 0.98-1.92; P = .07). Rates of pneumothorax and vasopressor use were similar. CONCLUSIONS Treatment with higher vs lower levels of PEEP was not associated with improved hospital survival. However, higher levels were associated with improved survival among the subgroup of patients with ARDS.
In this trial, high-frequency oscillatory ventilation was compared with conventional ventilation with a lung-protective protocol. When the study was stopped early, hospital mortality was 47% with ...HFOV versus 35% with the control ventilation strategy.
The acute respiratory distress syndrome (ARDS) is a common complication of critical illness.
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Mortality is high, and survivors often have long-term complications.
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Although mechanical ventilation is life-sustaining for patients with ARDS, it can perpetuate lung injury. Basic research suggests that repetitive overstretching or collapse of lung units with each respiratory cycle can generate local and systemic inflammation, contributing to multiorgan failure and death.
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Consistent with these findings are data from clinical trials that support the use of smaller tidal volumes (6 vs. 12 ml per kilogram of predicted body weight)
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and higher levels of positive end-expiratory pressure (PEEP). . . .
We show a significant improvement of modulation bandwidth from 2\times 1 photonic crystal vertical-cavity surface-emitting laser arrays. Control of injection bias conditions to array elements enables ...resonance tuning of each element with variation of the phase relation and coherence of the array, resulting in the ability to tailor the modulation response. A bandwidth of 37 GHz is obtained under highly single-mode coherent operation with narrow spectral width and increased output power while the laser array is biased at low current density. Lasers with such performance characteristics may greatly enhance high-rate data transfer in computer server, data center, and supercomputer applications with potentially long device lifetime.
Goligher et al. examine whether the mortality benefit of ventilation with lower Vt varies according to respiratory system elastance (Ers). In a secondary analysis of patients from five randomized ...trials of lower- versus higher-Vt ventilation strategies in ARDS and acute hypoxemic respiratory failure, the posterior probability of an interaction between the randomized Vt strategy and Ers on 60-day mortality was computed using Bayesian multivariable logistic regression. The mortality benefit of ventilation with lower Vt in ARDS varies according to elastance, suggesting that lung-protective ventilation strategies should primarily target driving pressure rather than Vt.
This analysis of previously reported trials shows that low tidal volumes, a key component of safer ventilation strategies, confer a protective effect against complications only if the lower volume ...results in a lower pulmonary driving pressure.
Mechanical-ventilation strategies that use lower end-inspiratory (plateau) airway pressures, lower tidal volumes (V
T
), and higher positive end-expiratory pressures (PEEPs) — collectively termed lung-protective strategies — have been associated with survival benefits in randomized clinical trials involving patients with the acute respiratory distress syndrome (ARDS).
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The different components of lung protection in those strategies, such as lower V
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, lower plateau pressure, and higher PEEP, can all reduce mechanical stresses on the lung, which are thought to induce ventilator-induced lung injury.
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Clinical trials, however, have reported conflicting responses to the manipulation of separate components of lung . . .
Passive and semipassive UHF RF identification (RFID) systems have traditionally been designed using scalar-valued differential radar cross section (DRCS) methods to model the backscattered signal ...from the tag. This paper argues that scalar-valued DRCS analysis is unnecessarily limiting because of the inherent coherence of the backscatter link and the complex-valued nature of load-dependent antenna-mode scattering from an RFID tag. Considering modulated backscatter in terms of complex-valued scattered fields opens the possibility of quadrature modulation of the backscatter channel. When compared with binary amplitude shift keying (ASK) or phase shift keying (PSK) based RFID systems, which transmit 1 bit of data per symbol period, and thus 1 bit per on-chip clock oscillator period, tags employing vector backscatter modulation can transmit more than 1 bit per symbol period. This increases the data rate for a given on-chip symbol clock rate leading to reduced on-chip power consumption and extended read range. Alternatively, tags employing an M-ary modulator can achieve log 2 M higher data throughput at essentially the same dc power consumption as a tag employing binary ASK or PSK. In contrast to the binary ASK or PSK backscatter modulation employed by passive and semipassive UHF RFID tags, such as tags compliant with the widely used ISO18000-6c standard, this paper explores a novel CMOS-compatible method for generating M-ary quadrature amplitude modulated (QAM) backscatter modulation. A new method is presented for designing an inductorless M-ary QAM backscatter modulator using only an array of switched resistances and capacitances. Device-level simulation and measurements of a four-state phase shift keying (4-PSK)/four-state quadrature amplitude modulated (4-QAM) modulator are provided for a semipassive (battery-assisted) tag operating in the 850-950-MHz band. This first prototype modulator transmits 4-PSK/4-QAM at a symbol rate of 200 kHz and a bit rate of 400 kb/s at a static power dissipation of only 115 nW.
The acute respiratory distress syndrome (ARDS) is a common reason for admission to an intensive care unit. Patients who had recovered from ARDS were followed for 5 years and were commonly found to ...have persistent weakness but relatively normal lung function.
The acute respiratory distress syndrome (ARDS) represents an important and costly public health problem.
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Prospective systematic evaluation of long-term outcomes among survivors of ARDS has been limited to 2 years of follow-up.
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Few comprehensive, longitudinal data have been obtained from survivors of critical illness with regard to 5-year pulmonary, functional, and health-related quality-of-life outcomes or health care utilization and costs. The Toronto ARDS follow-up study began in 1998 and enrolled relatively young patients with very severe lung injury and few coexisting illnesses.
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The primary goal of this 5-year follow-up study was to catalogue, quantify, and describe the extent of . . .
We report progress on phased 850 nm vertical-cavity surface-emitting laser arrays that can be designed to operate reliably through control of individual injection current to each laser element. In ...this manner, nearly all fabricated arrays can be biased to be mutually phase locked. This paper attempts to visualize and characterize the locking region between two neighboring lasers by measuring far-field visibility to create a two-dimensional visibility map. Experimental data show that the locking region can be shifted or changed by ambient temperature, asymmetric array design, and fabrication imperfections. Additionally, the relative intensity noise and harmonic distortion are measured to characterize the dynamic behavior of coherently coupled laser arrays in the locking region. Two-dimensional maps of total relative intensity noise and total harmonic distortion are created to visualize laser array dynamics in the locking region. The data show that the laser array must be carefully designed, biased, and modulated within the locking region to achieve an output signal with low noise, low distortion, and improved modulation performance.
Curriculum Windows Redux Poetter, Thomas S; Waldrop, Kelly; Raza, Syed Hassan
2022, 2022-08-01
eBook
Curriculum Windows Redux: What Curriculum Theorists Can Teach Us about Schools and Society Today is an effort by students of curriculum studies, along with their professor, to interpret and ...understand curriculum texts and theorists in contemporary terms.The authors explore how key books/authors from the curriculum field illuminate new possibilities forward for us as scholar educators today: How might the theories, practices, and ideas wrapped up in these curriculum texts still resonate with us, allow us to see backward in time and forward in time - all at the same time? How might these figurative windows of insight, thought, ideas, fantasy, and fancy make us think differently about curriculum, teaching, learning, students, education, leadership, and schools? Further, how might they help us see more clearly, even perhaps put us on a path to correct the mistakes and missteps of intervening decades and of today?The authors complete the Curriculum Windows series with this 7th book, Redux, providing a scholarly view of 33 books that should have been treated in the first 6 books based on the decades of the 1950s-2000s. The book's Foreword is by renowned curriculum theorist William H. Schubert.
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