Objective
Determine whether the size-arrival effect (SAE) occurs with immersive, 3D visual experiences and active collision-avoidance responses.
Background
When a small near object and a large far ...object approach the observer at the same speeds, the large object appears to arrive before the small object, known as the size-arrival effect (SAE), which may contribute to crashes between motorcycles and cars. Prior studies of the SAE were limited because they used two dimensional displays and asked participants to make passive judgments.
Method
Participants viewed approaching objects using a virtual reality (VR) headset. In an active task, participants ducked before the object hit them. In a passive prediction-motion (PM) judgment, the approaching object disappeared, and participants pressed a button when they thought the object would hit them. In a passive relative TTC judgment, participants reported which of two approaching objects would reach them first.
Results
The SAE occurred with the PM and relative TTC tasks but not with the ducking task. The SAE can occur in immersive 3D environments but is limited by the nature of the task and display.
Application
Certain traffic situations may be more prone to the SAE and have higher risk for collisions. For example, in left-turn scenarios (e.g., see Levulis, 2018), drivers make passive judgments when oncoming vehicles are far and optical expansion is slow, and binocular disparity putatively is ineffective. Collision-avoidance warning systems may be needed more in such scenarios than when vehicles are near and drivers’ judgments of TTC may be more accurate (DeLucia, 2008).
High- and low-density lipoproteins (HDL and LDL) are attractive targets for biomarker discovery. However, ultracentrifugation (UC), the current methodology of choice for isolating HDL and LDL, is ...tedious, requires large sample volume, results in sample loss, and does not readily provide information on particle size. In this work, human plasma HDL and LDL are separated and collected using semi-preparative asymmetrical flow field-flow fractionation (SP-AF4) and UC. The SP-AF4 and UC separation conditions, sample throughput, and liquid chromatography/mass spectrometry (LC/MS) lipidomic results are compared. Over 600 μg of total proteins is recovered in a single SP-AF4 run, and Western blot results confirm apoA1 pure and apoB100 pure fractions, consistent with HDL and LDL, respectively. The SP-AF4 separation requires ~ 60 min per sample, thus providing a marked improvement over UC which can span hours to days. Lipidome analysis of SP-AF4-prepared HDL and LDL fractions is compared to UC-prepared HDL and LDL samples. Over 270 lipids in positive MS mode and over 140 lipids in negative MS mode are identified by both sample preparation techniques with over 98% overlap between the lipidome. Additionally, lipoprotein size distributions are determined using analytical scale AF4 coupled with multiangle light scattering (MALS) and dynamic light scattering (DLS) detectors. These developments position SP-AF4 as a sample preparation method of choice for lipoprotein biomarker characterization and identification.
Graphical abstract
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Field-flow fractionation (FFF) is a family of techniques that was created especially for separating and characterizing macromolecules, nanoparticles, and micrometer-sized analytes. It is coming of ...age as new nanomaterials, polymers, composites, and biohybrids with remarkable properties are introduced and new analytical challenges arise due to synthesis heterogeneities and the motivation to correlate analyte properties with observed performance. Appreciation of the complexity of biological, pharmaceutical, and food systems and the need to monitor multiple components across many size scales have also contributed to FFF's growth. This review highlights recent advances in FFF capabilities, instrumentation, and applications that feature the unique characteristics of different FFF techniques in determining a variety of information, such as averages and distributions in size, composition, shape, architecture, and microstructure and in investigating transformations and function.
ABSTRACT
We report the results of the stellar occultation by (UII) Umbriel on 2020 September 21. The shadow crossed the USA and Canada, and 19 positive chords were obtained. A limb parameter ...accounted for putative topographic features in the limb fittings. Ellipse fittings were not robust – only upper limits were derived for the true size/shape of a putative Umbriel ellipsoid. The adopted spherical solution gives radius = 582.4 ± 0.8 km, smaller/close to 584.7 ± 2.8 km from Voyager II. The apparent ellipse fit results in a true semi-major axis of 584.9 ± 3.8 km, semi-minor axis of 582.3 ± 0.6 km, and true oblateness of 0.004 ± 0.008 for a putative ellipsoid. The geometric albedo was pV = 0.26 ± 0.01. The density was ρ = 1.54 ± 0.04 g cm−3. The surface gravity was 0.251 ± 0.006 m s−2 and the escape velocity was 0.541 ± 0.006 km s−1. Upper limits of 13 and 72 nbar (at 1σ and 3σ levels, respectively) were obtained for the surface pressure of a putative isothermal CO2 atmosphere at T = 70 K. A milliarcsecond precision position was derived: α = 02h30m28${_{.}^{\rm s}}$84556 ± 0.1 mas, δ = 14o19′36″.5836 ± 0.2 mas. A large limb parameter of 4.2 km was obtained, in striking agreement with opposite Southern hemisphere measurements by Voyager II in 1986. Occultation and Voyager results indicate that the same strong topography variation in the surface of Umbriel is present on both hemispheres.
Immediate expander/implant-based breast reconstruction after mastectomy has become more sought after by patients. Although many patients choose this technique due to good aesthetic outcomes, lack of ...donor site morbidity, and shorter procedure times, it is not without complications. The most reported complications include seroma, infection, hematoma, mastectomy flap necrosis, wound dehiscence, and implant exposure, with an overall complication rate as high as 45%. Closed incision negative pressure therapy (ciNPT) has shown value in wound healing and reducing complications; however, the current literature is inconclusive. We aimed to examine if ciNPT improves outcomes for patients receiving this implant-based reconstruction.
This is a retrospective single-institution study evaluating the ciNPT device, 3M Prevena Restor BellaForm, on breast reconstruction patients. The study was performed between July 1, 2019 and October 30, 2020, with 125 patients (232 breasts). Seventy-seven patients (142 breasts) did not receive the ciNPT dressing, and 48 patients (90 breasts) received the ciNPT dressing. Primary outcomes were categorized by major or minor complications. Age, BMI, and final drain removal were summarized using medians and quartiles, and were compared with nonparametric Mann-Whitney test. Categorical variables were compared using chi-square or Fisher exact test.
There was a statistically significant reduction in major complications in the ciNPT group versus the standard dressing group (
= 0.0247). Drain removal time was higher in the ciNPT group.
Our study shows that ciNPT may help reduce major complication rates in implant-based breast reconstruction patients.
•Stability of aggregate species is observed to be molar mass and size dependent.•Syringe shear stress is not detectable using AF4-MALS, but is observed by batch-mode DLS.•The focusing step, unique to ...AF4, does not impact anti-SA IgG aggregates stability.•Dilution in AF4 is shown to be significantly lower than widely perceived.•AF4 theory may provide more accurate sizes for weakly bound aggregates than online DLS.
The impact of asymmetrical flow field-flow fractionation (AF4) on protein aggregate species is investigated with the aid of multiangle light scattering (MALS) and dynamic light scattering (DLS). The experimental parameters probed in this study include aggregate stability in different carrier liquids, shear stress (related to sample injection), sample concentration (during AF4 focusing), and sample dilution (during separation). Two anti-streptavidin (anti-SA) IgG1 samples composed of low and high molar mass (M) aggregates are subjected to different AF4 conditions. Aggregates suspended and separated in phosphate buffer are observed to dissociate almost entirely to monomer. However, aggregates in citric acid buffer are partially stable with dissociation to 25% and 5% monomer for the low and high M samples, respectively. These results demonstrate that different carrier liquids change the aggregate stability and low M aggregates can behave differently than their larger counterparts. Increasing the duration of the AF4 focusing step showed no significant changes in the percent monomer, percent aggregates, or the average Ms in either sample. Syringe-induced shear related to sample injection resulted in an increase in hydrodynamic diameter (dh) as measured by batch mode DLS. Finally, calculations showed that dilution during AF4 separation is significantly lower than in size exclusion chromatography with dilution occurring mainly at the AF4 channel outlet and not during the separation. This has important ramifications when analyzing aggregates that rapidly dissociate (<∼2s) upon dilution as the size calculated by AF4 theory may be more accurate than that measured by online DLS. Experimentally, the dhs determined by online DLS generally agreed with AF4 theory except for the more well retained larger aggregates for which DLS showed smaller sizes. These results highlight the importance of using AF4 retention theory to understand the impacts of dilution on analytes.
This paper reports the first use of a remote sensing device to measure emissions from in-use marine vessels. Emissions from 307 small marine vessels were measured as they passed through the Hiram M. ...Chittenden locks near Seattle, WA. Of these vessels, 89 were matched to state registration information to allow for further analysis of emissions vs model year, fuel type, and engine type. Emission factors are reported for CO, HC, and NO x in grams of pollutant per kilogram of fuel. The measured emission factors generally agreed with those derived from laboratory studies. HC emissions are disproportionately skewed across the fleet where 40% of the emissions come from just 10% of the fleet. These are most likely due to the remaining two-stroke engines in the fleet. CO and HC emissions show no improvement with newer vessels.
We present the first case of traveler's diarrhea resulting in breast implant infection. An otherwise healthy 34-year-old female underwent breast augmentation. Five months later, while vacationing in ...Cancun, Mexico, she developed abdominal pain and diarrhea that progressed to include fevers and chills. Her symptoms persisted until she returned to the United States, at which point her primary care physician evaluated her on the fourth day of her illness. An abdominal CT scan was unremarkable; however, a complete metabolic panel demonstrated elevated transaminases. Her symptoms soon resolved without treatment. Fourteen days after symptom resolution, the patient developed right breast pain. She was evaluated in the surgical clinic where the breast was tender to palpation, swollen and without erythema. An ultrasound demonstrated a small amount of homogenous fluid surrounding the implant. She was prescribed amoxicillin-clavulanate 875-125 mg BID; however, she presented three days later with worsening pain, swelling and new erythema. She was taken to the operating room, where the abscess was incised, drained and the implant removed. Cultures grew
serogroup C. Patients should be counseled regarding the potential for hematogenous seeding of the breast cavity and implant following severe illness and bacteremia. It may be reasonable to provide patients with breast implants who are traveling to areas at high-risk for traveler's diarrhea or areas with limited medical resources with an antibiotic to take if moderate to severe symptoms of traveler's diarrhea were to develop while away.
•SP-AF4 channel dimensions are studied via a theoretical/experimental approach.•Channel breadth has largest impact on sample loading and least impact on resolution.•Milligram quantities of silica ...nanoparticles are fractionated using aqueous SP-AF4.•The position of the focusing band is found to impact retention and resolution.•Separation of Pt-Fe3O4 nanoparticles is the first demonstration of organic SP-AF4.
The design and performance of a semi-preparative asymmetrical flow field-flow fractionation (SP-AF4) channel are investigated with the objective of better understanding and exploiting the relationship between channel dimensions, sample loading, and resolution. Most size-based separations of nanometer and submicrometer particles are currently limited to analytical scale quantities (<100μg). However, there is a strong need to fractionate and collect larger quantities so that fundamental properties of the more narrowly dispersed fractions can be studied using additional characterization methods and for subsequent applications. In this work, dimensions of the spacer that defines the form of SP-AF4 channels are varied and their performances are assessed with respect to sample focusing position and loading. Separations are performed in aqueous and organic carrier fluids. A critical evaluation of channel dimensions showed that increasing the channel breadth is a practical and effective route to maintaining separation resolution while increasing sample loads to milligram quantities. Good size resolution (∼1.0) is achieved for separations of 10mg of 50 and 100nm silica nanoparticles suspended in water and up to 0.6mg of ∼10 to 35nm inorganic hybrid nanoparticles suspended in tetrahydrofuran. This work represents important advances in the understanding of SP-AF4 separations and extends sample loading capacities in both aqueous and organic solvents.
As emissions from nonroad mobile sources face increased regulatory scrutiny, a surprisingly few number of real-world, in-use measurements exist for these sources. This paper reports the first use of ...an open-path Remote Sensing Device (RSD) to measure emissions from ocean-going ships, including cruise ships. This noninvasive technique measured NOx and SO2 emission factors from 16 individually identified ocean-going ships as they passed under the Lions Gate Bridge in Vancouver, B.C. and their exhaust plumes passed through the sensing beam of the RSD on a bridge directly above. Ship NOx emissions generally agreed with previous studies showing no emissions trends across vessel type. Ship SO2 emissions were reasonable based on expected Environmental Control Area fuel sulfur requirements and corresponded to 0.4–2.4% sulfur in the fuels. This method's specificity of individual vessel SO2 measurements suggests that this technique could be used as a tool to detect high sulfur fuel use in vessels.
Display omitted
•Measured NOx and SO2 emissions from in-use ocean-going ships.•First emission measurements from individually identified in-use cruise ships.•Demonstration of a remote sensor that can estimate sulfur content in fuels from ships.
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