SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Shutter speed

143

The dramatic rise in the use of smartphones, tablets, and laptop computers over the past decade has raised concerns about potentially deleterious health effects of increased “screen time” (ST) and associated short-wavelength (blue) light exposure. We determined baseline associations and effects of 6 months' supplementation with the macular carotenoids (MC) lutein, zeaxanthin, and mesozeaxanthin on the blue-absorbing macular pigment (MP) and measures of sleep quality, visual performance, and physical indicators of excessive ST. Forty-eight healthy young adults with at least 6 h of daily near-field ST exposure participated in this placebo-controlled trial. Visual performance measures included contrast sensitivity, critical flicker fusion, disability glare, and photostress recovery. Physical indicators of excessive screen time and sleep quality were assessed via questionnaire. MP optical density (MPOD) was assessed via heterochromatic flicker photometry. At baseline, MPOD was correlated significantly with all visual performance measures (p < 0.05 for all). MC supplementation (24 mg daily) yielded significant improvement in MPOD, overall sleep quality, headache frequency, eye strain, eye fatigue, and all visual performance measures, versus placebo (p < 0.05 for all). Increased MPOD significantly improves visual performance and, in turn, improves several undesirable physical outcomes associated with excessive ST. The improvement in sleep quality was not directly related to increases in MPOD, and may be due to systemic reduction in oxidative stress and inflammation.

Concepts: Photosynthesis, Antioxidant, Carotenoid, Laptop, Zeaxanthin, Lutein, Xanthophyll, Shutter speed

138

This paper reports a controlled breakdown (CBD) method to fabricate multiple nanopores in a silicon nitride (SiNx) membrane with control over both nanopore count and nanopore diameter. Despite the stochastic process of the breakdown, we found that the nanopores created via CBD, tend to be of the same diameter. We propose a membrane resistance model to explain and control the multiple nanopores forming in the membrane. We prove that the membrane resistance can reflect the number of nanopores in the membrane and that the diameter of the nanopores is controlled by the exposure time and strength of the electric field. This controllable multiple nanopore formation via CBD avoids the utilization of complicated instruments and time-intensive manufacturing. We anticipate CBD has the potential to become a nanopore fabrication technique which, integrated into an optical setup, could be used as a high-throughput and multichannel characterization technique.

Concepts: Scientific method, Semiconductor, Control theory, Control, Control system, Shutter speed, Science of photography, Nanopore

31

Research investigating expressivity in children with autism spectrum disorder has reported flat affect or bizarre facial expressivity within this population; however, the impact expressivity may have on first impression formation has received little research input. We examined how videos of children with autism spectrum disorder were rated for expressivity by adults blind to the condition. We further investigated the friendship ratings given by 44 typically developing children to the same videos. These ratings were compared to friendship ratings given to video clips of typically developing children. Results demonstrated that adult raters, blind to the diagnosis of the children in the videos, rated children with autism spectrum disorder as being less expressive than typically developing children. These autism spectrum disorder children were also rated lower than typically developing children on all aspects of our friendship measures by the 44 child raters. Results suggest that impression formation is less positive towards children with autism spectrum disorder than towards typically developing children even when exposure time is brief.

Concepts: Autism, Pervasive developmental disorder, Child, Asperger syndrome, Autism spectrum, PDD-NOS, Adult, Shutter speed

28

Because tires contain approximately 1-2% zinc by weight, zinc leaching is an environmental concern associated with civil engineering applications of tire crumb rubber. An assessment of zinc leaching data from 14 studies in the published literature indicates that increasing zinc leaching is associated with lower pH and longer leaching times, but the data display a wide range of zinc concentrations, and do not address the effect of crumb rubber size or the dynamics of zinc leaching during flow through porous crumb rubber. The present study was undertaken to investigate the effect of crumb rubber size using the Synthetic Precipitation Leaching Procedure (SPLP), the effect of exposure time using quiescent batch leaching tests, and the dynamics of zinc leaching using column tests. Results indicate that zinc leaching from tire crumb rubber increases with smaller crumb rubber and longer exposure time. Results from SPLP and quiescent batch leaching tests are interpreted with a single-parameter leaching model that predicts a constant rate of zinc leaching up to 96 hr. Breakthrough curves from column tests displayed an initial pulse of elevated zinc concentration (~3 mg/L) before settling down to a steady-state value (~0.2 mg/L), and were modeled with the software package HYDRUS-1D. Washing crumb rubber reduces this initial pulse but does not change the steady-state value. No leaching experiment significantly reduced the reservoir of zinc in the crumb rubber.

Concepts: Time, Concentration, Shutter speed, Synthetic rubber, Vulcanization, The Crumbs, Tire, Crumb rubber

26

Abstract Objective: This study compared three model decontaminant solutions (distilled water, 10% distilled water and soap and methanol) for their ability to remove salicylic acid and aminophylline from an in vitro skin model. Materials and methods: Human abdominal skin was dosed with 20 µL of either [(14)C]-aminophylline or [(14)C]-salicylic acid on 1 cm(2) per skin. After each exposure time (5, 30 and 60 min post-dosing, respectively), surface skin was washed three times with each solution and tape stripped 10 times. Wash solutions, tape strips, receptor fluid and remaining skin were then analyzed with liquid scintillation counting to quantify the amount of salicylic acid and aminophylline. Results: Total mass balance recovery for each chemical at three time exposure points was between 73.6 and 101.5%, except at 60 min where aminophylline was only 42.5%. Majority of salicylic acid and aminophylline were recovered from washing solution when compared to stratum corneum, epidermis, dermis, surrounding skin and receptor fluid. Conclusion: The three tested decontaminates possessed similar effectiveness in removing lipophilic and hydrophilic chemicals from the skin. Due to diminishing decontamination efficacy with time, it is suggested that skin should be washed as soon as possible following contamination to minimize percutaneous penetration and the deleterious effects associated with skin reservoir content.

Concepts: Chemistry, Skin, Liquid, Epidermis, Shutter speed, Scintillation counter, Washing, WASH

25

The effect of exposure time, temperature, food simulants, especially additives on the release of silver from nanosilver-polyethylene composite films to food simulants has been studied. Two different type of nanosliver-polyethylene composite films (with or without additives) were chosen to conduct the experiment with the aim of exploring the behavior of silver migration. It was shown that the migration of silver into 50% ethanol at 40℃ and 70℃ was much less than that into 3% acetic acid. With the increase of exposure time and the temperature, the release of silver increased. The migration even continued after a long exposure time (14 days at 20℃, 10 days at 40℃, and 6 days at 70℃ respectively). Only about 0.15‰ of silver migrated from composite films with the additives into 3% acetic acid after 6 days of exposure at 70℃, while about 1.3% of silver migrated from composite films that did not contain additives under the same conditions. This could be due to the fact that the addition of the antioxidants and light stabilisers prevent silver from being oxidised, which is an important way for the release of silver.

Concepts: Oxygen, Ethanol, Acetic acid, Exposure, Vinegar, Photography, Shutter speed, Exposure value

24

We systematically examined and updated the scientific literature on the association between screen time (e.g., television, computers, video games, and mobile devices) and sleep outcomes among school-aged children and adolescents. We reviewed 67 studies published from 1999 to early 2014. We found that screen time is adversely associated with sleep outcomes (primarily shortened duration and delayed timing) in 90% of studies. Some of the results varied by type of screen exposure, age of participant, gender, and day of the week. While the evidence regarding the association between screen time and sleep is consistent, we discuss limitations of the current studies: 1) causal association not confirmed; 2) measurement error (of both screen time exposure and sleep measures); 3) limited data on simultaneous use of multiple screens, characteristics and content of screens used. Youth should be advised to limit or reduce screen time exposure, especially before or during bedtime hours to minimize any harmful effects of screen time on sleep and well-being. Future research should better account for the methodological limitations of the extant studies, and seek to better understand the magnitude and mechanisms of the association. These steps will help the development and implementation of policies or interventions related to screen time among youth.

Concepts: Systematic review, Measurement, The Association, Error, GNU Screen, Shutter speed

22

Mosses are well known as biomonitors of fresh water for metal pollutants, but no studies were reported so far about their ability to intercept plastic particles, although this kind of pollution has become an urgent issue worldwide. In the present work, the interaction between the moss Sphagnum palustre L. cultured in vitro and polystyrene nanoparticles (NPs) was studied for the first time in a laboratory experiment, in the view of using moss transplants for detecting microplastics in fresh water environments. The ability of S. palustre to intercept and retain polystyrene, and the effects of vitality and post-exposure washing on NP retention by moss were tested. Fluorescence microscope observations showed that polystyrene NPs were retained by moss leaves in form of small (the most abundant fraction) and large aggregates. Particle count analysis highlighted that the number of particles increased while increasing the exposure time. Moreover, moss devitalization favored NP accumulation, likely because of cell membrane damages occurred in dead moss material. Post-exposure washing induced a loss of larger aggregates, suggesting that exposure time is a key point to be carefully evaluated in field conditions. These results encourage the use of S. palustre transplants for monitoring microplastics contamination of fresh water environments.

Concepts: Environment, Plant, Freshwater, Moss, Shutter speed, Sphagnum, Sphagnopsida, Fresh Water

12

Cell-sized vesicles have tremendous potential both as miniaturised pL reaction vessels and in bottom-up synthetic biology as chassis for artificial cells. In both these areas the introduction of light-responsive modules affords increased functionality, for example, to initiate enzymatic reactions in the vesicle interior with spatiotemporal control. Here we report a system composed of nested vesicles where the inner compartments act as phototransducers, responding to ultraviolet irradiation through diacetylene polymerisation-induced pore formation to initiate enzymatic reactions. The controlled release and hydrolysis of a fluorogenic β-galactosidase substrate in the external compartment is demonstrated, where the rate of reaction can be modulated by varying ultraviolet exposure time. Such cell-like nested microreactor structures could be utilised in fields from biocatalysis through to drug delivery.

Concepts: DNA, Adenosine triphosphate, Enzyme, Chemical reaction, Catalysis, Enzymes, Sterilization, Shutter speed

12

Whole body cryotherapy (WBC) is the therapeutic application of extreme cold air for a short duration. Minimal evidence is available for determining optimal exposure time.

Concepts: Common cold, Duration, Shutter speed, Rugby league