Helicity and Polarization Gradient Optical Trapping in Evanescent Fields.

Optical traps using nonconservative forces instead of conservative intensity-gradient forces expand the trap parameter space. Existing traps with nonconservative helicity-dependent forces are limited to chiral particles and fields with helicity gradients. We relax these constraints by proposing helicity and polarization gradient optical trapping of achiral particles in evanescent fields. We further propose an optical switching system in which a microsphere is trapped and optically manipulated around a microfiber using polarization gradients. Our Letter deepens the understanding of light-matter interactions in polarization gradient fields and expands the range of compatible particles and stable trapping fields.

A High Aspect Ratio Inverse-Designed Holey Metalens.

Free-standing nanofins or pillar meta-atoms are the most common constituent building blocks in metalenses and metasurfaces in general. Here, we present an alternative metasurface geometry based on high aspect ratio via-holes. We design and characterize metalenses comprising ultradeep via-holes in 5 µm thick free-standing silicon membranes with hole aspect ratios approaching 30:1. These metalenses focus incident infrared light into a diffraction-limited spot. Instead of shaping the metasurface optical phase profile alone, we engineer both transmitted phase and amplitude profiles simultaneously by inverse-designing the lens effective index profile. This approach improves the impedance match between the incident and transmitted waves, thereby increasing the focusing efficiency. The holey platform increases the accessible aspect ratio of optical nanostructures without sacrificing mechanical robustness. The high nanostructure aspect ratio also increases the chromatic group delay range attainable, paving the way for a generation of high aspect ratio ruggedized flat optics, including large-area broadband achromatic metalenses.

Corrigendum to "Evaluation of different air distribution systems in a commercial airliner cabin in terms of comfort and COVID-19 infection risk" Build. Environ., Volume 208, January 2022, 108590.

[This corrects the article DOI: 10.1016/j.buildenv.2021.108590.].

Evaluation of different air distribution systems in a commercial airliner cabin in terms of comfort and COVID-19 infection risk.

The air distribution system in an airliner plays a key role in maintaining a comfortable and healthy environment in the aircraft cabin. To evaluate the performance of a novel displacement ventilation (DV) system and a traditional mixing ventilation (MV) system in an airliner cabin, this study conducted experiments and simulations in a seven-row cabin mockup. This investigation used ultrasonic anemometers and T-thermocouples to measure the air velocity, temperature and distribution of 1 µm and 5 µm particles. Simulation verifications were performed for these operating conditions, and additional scenarios with different occurrence source locations were also simulated. This study combined the Wells-Riley equation with a real case based on a COVID-19 outbreak among passengers on a long-distance bus to obtain the COVID-19 quanta value. Through an evaluation of the airflow organization, thermal comfort, and risk of COVID-19 infection, the two ventilation systems were compared. This investigation found that polydisperse particles should be used to calculate the risk of infection in airliner cabins. In addition, at the beginning of the pandemic, the infection risk with DV was lower than that with MV. In the middle and late stages of the epidemic, the infection risk with MV can be reduced when passengers wear masks, leading to an infection risk approximately equal to that of DV.

Influencing factors in the simulation of airflow and particle transportation in aircraft cabins by CFD.

To control the transport of particles such as the SARS-CoV-2 virus in airliner cabins, which is a significant concern for the flying public, effective ventilation systems are essential. Validated computational fluid dynamics (CFD) models are frequently and effectively used to investigate air distribution and contaminant transportation. The complex geometry and airflow characteristics in airliner cabins pose a challenge to numerical CFD validation. The objective of this investigation was to identify accurate and affordable validation processes for studying the airflow field and particulate contaminant distribution in airliner cabins during the design process for different ventilation systems. This study quantitatively evaluated the effects of ventilation system, turbulence model, particle simulation method, geometry simplification, and boundary condition assignment on airflow and particulate distributions in airliner cabins with either a mixing ventilation (MV) system or a displacement ventilation (DV) system calculated by CFD. The results showed that among four turbulence models, the standard k-ε, RNG k-ε, realizable k-ε and SST k-ω models, the prediction by the realizable k-ε model agreed most closely with the experimental data. Meanwhile, the steady Eulerian method provided a reasonable prediction of the particle concentration field with low computing cost. The computational domain should be simplified differently for the DV system and the MV system with consideration of the simulation accuracy and computing cost. For more accurate modeling results, the boundary conditions should be assigned in greater detail, taking into account the uniformity on the boundary.

Influencing factors of carbonyl compounds and other VOCs in commercial airliner cabins: On-board investigation of 56 flights.

Volatile organic compounds (VOCs) as a non-negligible aircraft cabin air quality (CAQ) factor influence the health and comfort of passengers and crew members. On-board measurements of carbonyls (short-chain (C1 -C6 )) and other volatile organic compounds (VOCs, long-chain (C6 -C16 )) with a total of 350 samples were conducted in 56 commercial airliner cabins covering 8 aircraft models in this study. The mean concentration for each individual carbonyl compound was between 0.3 and 8.3 µg/m3 (except for acrolein & acetone, average = 20.7 µg/m3 ) similar to the mean concentrations of other highly detected VOCs (long-chain (C6 -C16 ), 97% of which ranged in 0-10 µg/m3 ) in aircraft cabins. Formaldehyde concentrations in flights were significantly lower than in residential buildings, where construction materials are known formaldehyde sources. Acetone is a VOC emitted by humans, and its concentration in flights was similar to that in other high-occupant density transportation vehicles. The variation of VOC concentrations in different flight phases of long-haul flights was the same as that of CO2 concentration except for the meal phase, which indicates the importance of cabin ventilation in diluting the gaseous contaminants, while the sustained and slow growth of the VOC concentrations during the cruising phase in short-haul flights indicated that the ventilation could not adequately dilute the emission of VOCs. For the different categories of VOCs, the mean concentration during the cruising phase of benzene series, aldehydes, alkanes, other VOCs (detection rate > 50%), and carbonyls in long-haul flights was 44.2 µg/m3 , 17.9 µg/m3 , 18.6 µg/m3 , 31.5 µg/m3 , and 20.4 µg/m3  lower than those in short-haul flights, respectively. Carbonyls and d-limonene showed a significant correlation with meal service (p < 0.05). Unlike the newly decorated rooms or new vehicles, the inner materials were not the major emission sources in aircraft cabins. Practical Implications. The on-board measurements of 56 flights enrich the VOC database of cabin environment, especially for carbonyls. The literature review of carbonyls in the past 20 years contributes to the understanding the current status of cabin air quality (CAQ). The analysis of VOC concentration variation for different flight phases, flight duration, and aircraft age lays a foundation for exploring effective control methods, including ventilation and purification for cabin VOC pollution. The enriched VOC data is helpful to explore the key VOCs of aircraft cabin environment and to evaluate the acute/chronic health exposure risk of pollutants for passengers and crew members.

Mobile Interventional Stroke Team Model Improves Early Outcomes in Large Vessel Occlusion Stroke: The NYC MIST Trial.

BACKGROUND AND PURPOSE: Triage of patients with emergent large vessel occlusion stroke to primary stroke centers followed by transfer to comprehensive stroke centers leads to increased time to endovascular therapy. A Mobile Interventional Stroke Team (MIST) provides an alternative model by transferring a MIST to a Thrombectomy Capable Stroke Center (TSC) to perform endovascular therapy. Our aim is to determine whether the MIST model is more time-efficient and leads to improved clinical outcomes compared with standard drip-and-ship (DS) and mothership models. METHODS: This is a prospective observational cohort study with 3-month follow-up between June 2016 and December 2018 at a multicenter health system, consisting of one comprehensive stroke center, 4 TSCs, and several primary stroke centers. A total of 228 of 373 patients received endovascular therapy via 1 of 4 models: mothership with patient presentation to a comprehensive stroke center, DS with patient transfer from primary stroke center or TSC to comprehensive stroke center, MIST with patient presentation to TSC and MIST transfer, or a combination of DS with patient transfer from primary stroke center to TSC and MIST. The prespecified primary end point was initial door-to-recanalization time and secondary end points measured additional time intervals and clinical outcomes at discharge and 3 months. RESULTS: MIST had a faster mean initial door-to-recanalization time than DS by 83 minutes (P<0.01). MIST and mothership had similar median door-to-recanalization times of 192 minutes and 179 minutes, respectively (P=0.83). A greater proportion had a complete recovery (National Institutes of Health Stroke Scale of 0 or 1) at discharge in MIST compared with DS (37.9% versus 16.7%; P<0.01). MIST had 52.8% of patients with modified Rankin Scale of ≤2 at 3 months compared with 38.9% in DS (P=0.10). CONCLUSIONS: MIST led to significantly faster initial door-to-recanalization times compared with DS, which was comparable to mothership. This decrease in time has translated into improved short-term outcomes and a trend towards improved long-term outcomes. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03048292.

Evaluating the commercial airliner cabin environment with different air distribution systems.

Ventilation systems for commercial airliner cabins are important in reducing contaminant transport and maintaining thermal comfort. To evaluate the performance of a personalized displacement ventilation system, a conventional displacement ventilation system, and a mixing ventilation system, this study first used the Wells-Riley equation integrated with CFD to obtain the SARS quanta value based on a specific SARS outbreak on a flight. This investigation then compared the three ventilation systems in a seven-row section of a fully occupied, economy-class cabin in Boeing 737 and Boeing 767 airplanes. The SARS quanta generation rate obtained for the index patient could be used in future studies. For all the assumed source locations, the passengers' infection risk by air in the two planes was the highest with the mixing ventilation system, while the conventional displacement ventilation system produced the lowest risk. The personalized ventilation system performed the best in maintaining cabin thermal comfort and can also reduce the infection risk. This system is recommended for airplane cabins.

CHARACTERIZATION OF THE CHOROIDAL VASCULATURE IN MYOPIC MACULOPATHY WITH OPTICAL COHERENCE TOMOGRAPHIC ANGIOGRAPHY.

PURPOSE: To characterize the choriocapillaris (CC) in highly myopic eyes with myopic maculopathy, using optical coherence tomographic angiography. METHODS: Prospective, clinic-based study of 42 eyes of 38 patients with high myopia (≤-6 diopters and axial length ≥26.5 mm). Myopic maculopathy was graded from fundus photographs according to the Meta-Analysis for Pathologic Myopia classification. Macular 3 × 3 mm en face optical coherence tomographic angiographic images were obtained with swept-source optical coherence tomographic angiography and graded for CC flow impairment as follows: 1) intact CC, 2) focal (<1 mm), and 3) extensive (>1 mm). RESULTS: Of the 42 eyes, 17 (39.5%) had tessellated fundus, 20 (46.5%) had diffuse, and 6 (14.0%) had patchy atrophy. Choriocapillaris flow impairment was observed in all eyes with diffuse and patchy atrophy. Even in eyes with tessellated fundus only, CC signal voids were seen in 3 eyes (17.6%). With increasingly severe myopic maculopathy, the pattern of CC flow impairment changed from predominantly focal to predominantly extensive. CONCLUSION: Choriocapillaris flow impairment was observed in many highly myopic eyes, even in those with mild fundus changes, and worsened with increasing severity of myopic maculopathy. Longitudinal studies are needed to assess whether CC flow impairment predicts the risk of myopic maculopathy progression.

Prediction of particle deposition around the cabin air supply nozzles of commercial airplanes using measured in-cabin particle emission rates.

Enhanced soiling on the surfaces around air supply nozzles due to particle deposition is frequently observed in commercial airliners. The problem is worsened by severe outdoor air pollution and flight delays in China. The particles in an aircraft cabin originate from both outdoor and in-cabin sources. This study conducted measurements on multiple commercial flights to obtain particle emission rates from in-cabin sources. Additional experiments on a retired MD-82 airplane provided justification of the in-flight measurements. The in-cabin sources emitted more particles during boarding/deplaning than during meal servicing and sitting. The average PM2.5 emission rates were 7.2, 2.6, 1.9, and 1.8 (µg/min per person), respectively, during the boarding/deplaning, sitting on the ground, sitting in the air, and meal servicing. The corresponding PM10 emission rates were 15.4, 6.1, 5.3, and 5.4 (µg/min per person), respectively, for these four periods. The average particle emission rate from in-cabin sources varied seasonally and was the highest in winter. With the measured data, this investigation used a CFD model to predict the accumulation of particles deposited around the nozzles of an airplane, taking into account the flight routes and the outdoor particle concentrations at the airports where the airplanes were parked. For the most polluted airplane in China, the dirty spots/areas around the nozzles inside the airplane became visible after 6 months. The method proposed in this study can be used for any commercial airplane to predict the accumulation of particles deposited around the air supply nozzles.

An innovative personalized displacement ventilation system for airliner cabins.

In airliner cabins, mixing ventilation systems with gaspers are not efficient in controlling contaminant transport. To improve the cabin environment, this investigation proposed an innovative ventilation system that would reduce contaminant transport and maintain thermal comfort. We manufactured and installed the proposed ventilation system in an occupied seven-row, single-aisle aircraft cabin mockup. Air velocity, air temperature, and contaminant distribution in the cabin mockup were obtained by experimental measurements. The investigation used the experimental data to validate the results of CFD simulation. The validated CFD program was then used to study the impact of the locations and number of exhausts on contaminant removal and thermal comfort in a one-row section of a fully occupied Boeing-737 cabin. Although the diffusers in the proposed system were close to the passengers' legs, the air velocity magnitude was acceptable in the lower part of the cabin and the leg area. The proposed system provided an acceptable thermal environment in the cabin, although passengers could feel cold when placing their legs directly in front of the diffusers. The four-exhaust configuration of the new ventilation system was the best, and it decreased the average exposure in the cabin by 57% and 53%, respectively, when compared with the mixing and displacement ventilation systems.

Mobile Interventional Stroke Teams Lead to Faster Treatment Times for Thrombectomy in Large Vessel Occlusion.

BACKGROUND AND PURPOSE: Endovascular recanalization treatment for acute ischemic stroke is a complex, time-sensitive intervention. Trip-and-treat is an interhospital service delivery model that has not previously been evaluated in the literature and consists of a shared mobile interventional stroke team that travels to primary stroke centers to provide on-site interventional capability. We compared treatment times between the trip-and-treat model and the traditional drip-and-ship model. METHODS: We performed a retrospective analysis on 86 consecutive eligible patients with acute ischemic stroke secondary to large vessel occlusion who received endovascular treatment at 4 hospitals in Manhattan. Patients were divided into 2 cohorts: trip-and-treat (n=39) and drip-and-ship (n=47). The primary outcome was initial door-to-puncture time, defined as the time between arrival at any hospital and arterial puncture. We also recorded and analyzed the times of last known well, IV-tPA (intravenous tissue-type plasminogen activator) administration, transfer, and reperfusion. RESULTS: Mean initial door-to-puncture time was 143 minutes for trip-and-treat and 222 minutes for drip-and-ship (P<0.0001). Although there was a trend in longer puncture-to-recanalization times for trip-and-treat (P=0.0887), initial door-to-recanalization was nonetheless 79 minutes faster for trip-and-treat (P<0.0001). There was a trend in improved admission-to-discharge change in National Institutes of Health Stroke Scale for trip-and-treat compared with drip-and-ship (P=0.0704). CONCLUSIONS: Compared with drip-and-ship, the trip-and-treat model demonstrated shorter treatment times for endovascular therapy in our series. The trip-and-treat model offers a valid alternative to current interhospital stroke transfers in urban environments.

Investigating the impact of gaspers on cabin air quality in commercial airliners with a hybrid turbulence model.

It is not clear whether turning on the gaspers in the cabins of commercial airliners actually improves the air quality. To answer this question, this study first developed a hybrid turbulence model which was suitable for predicting the air distribution in an aircraft cabin with gaspers turned on. Next, the investigation validated the model using two sets of experimental data from a cabin mockup and an actual airplane. This study then used the validated model to systematically investigate the impact of gaspers on cabin air quality in a seven-row section of the fully-occupied, economy-class cabin of Boeing 767 and 737 airplanes. The CFD calculations formed a database consisting of 9660 data points that provide information about SARS infection risk. It was found that the distribution of opened gaspers can influence the infection risk for passengers. Even though the gasper supplies clean air, it is possible for it to have a negative impact on the passengers' health. Statistically speaking, the overall effect of turning on the gaspers on the mean infection risk for the general population was neutral.

Congenital heart disease in low-birth-weight infants: effects of small for gestational age (SGA) status and maturity on postoperative outcomes.

Few studies have examined the role that small for gestational age (SGA) status plays in postoperative outcomes for low-birth-weight (LBW) infants with congenital heart disease (CHD). This study aimed to examine the effect of SGA status, gestational and chronologic age, and weight on differences in morbidities and mortalities during the immediate postoperative hospitalization period. The charts of infants with CHD weighing less than 2.5 kg who underwent operative repair during the neonatal period between 2004 and 2011 were reviewed. Infants with an isolated patent ductus arteriosus were excluded from the study. Data on hospital morbidities and mortality before discharge were collected. The study identified 136 LBW infants with a diagnosis of CHD. Among the 74 infants who underwent surgery and had complete chart records, the SGA infants had a higher gestational age at birth (36.8 vs. 32.3 weeks; p < 0.0001). The SGA and non-SGA infants did not differ in terms of survival to discharge or immediate postoperative outcomes. A lower weight at surgery was significantly associated with an increased risk of postoperative infection. In contradistinction, an older postnatal age at surgery was associated with an increased risk of preoperative infection (p < 0.0001). Additionally, lower gestational age at birth was associated with home oxygen use, higher tracheostomy rates, and discharge with a gastrostomy tube. Small for gestational age status played no protective role in the outcome for LBW infants after primary surgery for CHD. A weight of 2.4 kg or greater at the time of surgery was associated with lower rates of postoperative infections. Greater duration of time between birth and surgery was associated with a greater risk of preoperative infection. A gestational age of 32 weeks or more at birth was associated with decreased morbidities, which could influence obstetric management.

Urinary tract infections in a neonatal intensive care unit.

OBJECTIVE: Our aim was to describe laboratory findings and imaging results for neonatal patients diagnosed with urinary tract infection (UTI). STUDY DESIGN: Medical records were reviewed for infants diagnosed with UTI in a single neonatal intensive care unit (NICU) over a 13-year period. RESULTS: Of the 8,241 patients admitted to the NICU during the study period, 137 infants were diagnosed with UTI. Imaging was reviewed for 101 patients. Renal pelvis dilation was found in 34% of patients and vesicoureteral reflux was found in 21%. Renal pelvis dilation was not associated with reflux (OR: 0.53 [95% CI: 0.18-1.5]). The sensitivity of urinalysis to detect a positive culture was 76%, and the specificity was 41%. Tests of cure for bacterial infections were uniformly negative. CONCLUSION: Renal pelvis dilation was common but not associated with reflux among NICU patients diagnosed with UTI. Diagnostic criteria in this population are not well defined, and guidelines are needed for diagnosis and management of UTIs in NICU patients.

All-Glass 100 mm Diameter Visible Metalens for Imaging the Cosmos.

Metasurfaces, optics made from subwavelength-scale nanostructures, have been limited to millimeter-sizes by the scaling challenge of producing vast numbers of precisely engineered elements over a large area. In this study, we demonstrate an all-glass 100 mm diameter metasurface lens (metalens) comprising 18.7 billion nanostructures that operates in the visible spectrum with a fast f-number (f/1.5, NA = 0.32) using deep-ultraviolet (DUV) projection lithography. Our work overcomes the exposure area constraints of lithography tools and demonstrates that large metasurfaces are commercially feasible. Additionally, we investigate the impact of various fabrication errors on the imaging quality of the metalens, several of which are specific to such large area metasurfaces. We demonstrate direct astronomical imaging of the Sun, the Moon, and emission nebulae at visible wavelengths and validate the robustness of such metasurfaces under extreme environmental thermal swings for space applications.

Does angiotensin-converting enzyme inhibitor use exacerbate hereditary angioedema?

BACKGROUND: Approximately 2% of angioedema (AE) patients have a hereditary or an acquired deficiency of the complement 1 (C1) esterase inhibitor (C1 INH) gene. Some case reports indicate an association between angiotensin-converting enzyme inhibitor (ACEI) use and exacerbation of hereditary AE (HAE). OBJECTIVE: The aim of this retrospective study is to investigate the association between HAE and ACEI use in a larger patient population. METHODS: A retrospective chart review of patients who presented with AE and patients with diagnostic serum assays for functional C1 INH, C1 INH antigenic protein, C1q, C1q immune complex (C1q IC), and complement 4 (C4) regardless of medical complaint. Descriptive statistics were used to analyze the data. RESULTS: A total of 1594 patients had complement levels measured (136 C1 INH, 55 C1q, 10 C1q IC, and 1500 C4), of which 156 (9.7%) patients presented with AE. Angiotensin-converting enzyme inhibitor use was documented in 747 (47%) patients. Low C1 INH was detected in one patient with recurrent AE who was not taking ACEI. Another patient who presented with recurrent AE was found to have systemic lupus erythematosus with abnormal C4, C1q, and C1q IC, but normal C1 INH. A low C4 level was present in 94 patients, 4 of which had AE. CONCLUSIONS: The risk of exacerbating HAE by ACEI might be present, but we did not find any association in this retrospective study. Further studies are needed to determine the existence of this association.

Ultrasound guidance versus landmark guidance for intrathecal baclofen pump refill: A randomized pilot study.

BACKGROUND: Refilling difficult-to-access intrathecal baclofen (ITB) pumps by a trainee can result in longer procedures, more needle punctures, and more frequent attending interventions. Though ultrasound guidance can be used, there has not been an investigation into the impact of ultrasound guidance on refill outcomes. OBJECTIVE: To determine the feasibility of ultrasound guidance during difficult ITB refills to improve the experience of patients and providers. DESIGN: Nonblinded, randomized controlled trial with crossover element. SETTING: Outpatient clinic at a tertiary academic rehabilitation hospital. PARTICIPANTS: Patients ≥18 years old with historically difficult refills who were scheduled for repeat refills. "Difficult" was defined as body mass index > 30.0, a deep/tilted pump, previously requiring >1 skin puncture, or previously needing special positioning to access. INTERVENTIONS: Consented participants were randomized into a template-guided group (control) or an ultrasound-guided group (experimental) using a coin flip. Patients were crossed over if (1) a second refill occurred during the study period or (2) the randomized technique failed. MAIN OUTCOME MEASURES: The primary measure was time spent with needle under skin (seconds). Number of needle punctures and needle passes, frequency of attending intervention, pain during and after the procedure, patient satisfaction, and practitioner perceived difficulty were investigated. RESULTS: Seventeen patients underwent 21 refills (12 template guided and 9 ultrasound guided). No patients experienced adverse events. Although without statistically significant difference, the average time in the experimental group was shorter than the control (175 seconds vs 401 seconds), there were fewer episodes of multiple needle punctures (0 vs 2), multiple needle passes (2 vs 5), and attending interventions (0 vs 3) in the experimental group. No significant/clinical difference was found in pain during procedure, pain after procedure, patient satisfaction, or practitioner subjective difficulty. CONCLUSIONS: This pilot study demonstrates that ultrasound-guided ITB refills may reduce time spent with the needle in the skin, number of needle punctures, number of needle passes, and frequency of attending intervention during trainee refilling of pumps that are difficult to access.

Tailoring Light-Weight Aggregates for Concrete 3D Printing Applications.

Concrete 3D printing is a sustainable solution for manufacturing efficient designs and creating less waste, and selecting the optimal materials to use can amplify the advantages of this technology. In this study, we explore printing lightweight concrete by replacing normal weight aggregate with lightweight aggregates such as cenospheres, perlite, and foam beads. We adopt a systematic approach to investigate mixtures using different formulation methods such as the specific gravity and packing factor methods to improve the printing and mechanical performances of the mixtures. The rheological results showed significant improvement in the flow characteristics of the different mixtures using both the specific gravity method and the packing factor method to formulate the mixtures. Furthermore, a statistical tool was used to achieve optimal performance of the mixtures in terms of high specific compressive strength, high flow characteristics, and good shape retention capability by maximizing the specific compressive strength ratio, slump flow, and the static yield stress, while minimizing the slump, dynamic yield stress, and plastic viscosity. With the above design objectives, the optimal percentages of the aggregate replacements (cenosphere, perlite, and EPS foam beads) were 42%, 68%, and 44%, respectively. Finally, the optimized results also showed that the mixture with cenosphere aggregate replacement had the highest specific strength.