SciCombinator

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

Concept: Exposure value

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

1

Sources of variability in the comet assay include variations in the protocol used to process the cells, the microscope imaging system and the software used in the computerized analysis of the images. Here we focus on the effect of variations in the microscope imaging system and software analysis using fixed preparations of cells and a single cell processing protocol. To determine the effect of the microscope imaging and analysis on the measured percentage of damaged DNA (% DNA in tail), we used preparations of mammalian cells treated with etoposide or electrochemically induced DNA damage conditions and varied the settings of the automated microscope, camera, and commercial image analysis software. Manual image analysis revealed measurement variations in percent DNA in tail as high as 40% due to microscope focus, camera exposure time and the software image intensity threshold level. Automated image analysis reduced these variations as much as three-fold, but only within a narrow range of focus and exposure settings. The magnitude of variation, observed using both analysis methods, was highly dependent on the overall extent of DNA damage in the particular sample. Mitigating these sources of variability with optimal instrument settings facilitates an accurate evaluation of cell biological variability.

Concepts: DNA, Gene, Adenosine triphosphate, Histone, Optics, DNA repair, Photography, Exposure value

1

The IFM2009-02 trial studied pomalidomide (4mg daily, 21/28 versus 28/28) and dexamethasone in very advanced relapsed or refractory multiple myeloma (RRMM). We observed that 40% of patients had a prolonged PFS and subsequently OS. We sought to analyze the characteristics of these patients and study the effect of long exposure to pomalidomide.

Concepts: Multiple myeloma, Thalidomide, Lenalidomide, Cultural studies, Exposure, Dexamethasone, Spinal cord compression, Exposure value

0

A study of the respiratory health of grain farmers in Alberta, Canada was carried out in March 2002. Two populations were identified: members, in 1983, of a province-wide farm organisation, and grain farmers registered with the provincial agriculture department. A telephone interview addressed pesticide use (using pre-circulated trade names), chronic disease and respiratory symptoms. Pesticide ingredients were identified from provincial crop protection guides. Total years of use were calculated for seven chemical groups. Consent for linkage to administrative health records was obtained in 2009. A likelihood score (Lscore) is computed, relating symptoms to asthma diagnosis. Self-reported asthma and the Lscore are examined against duration of pesticide exposures. Of the 10,767 farmers listed, 2426 were still living, had farmed grain and were interviewed; 1371 were re-contacted and matched to health records. After allowance for confounders, years of exposure to phenoxy compounds are related to self-reported asthma and Lscore. Compared to no exposure, the adjusted odds ratios (95% Confidence Intervals for self-reported asthma for short, medium and long exposure to phenoxy compounds are 1.29 (0.66-2.52), 2.52 (1.25-5.09), and 3.18 (1.54-6.58), and for Lscore are 1.19 (0.91-1.55), 1.50 (1.13-1.99), and 1.58 (1.18-2.12). We conclude that lifetime exposure to phenoxy herbicides is associated with an increased risk of asthma.

Concepts: Medicine, Asthma, Chronic, Confidence interval, Pesticide, Exposure, Nuisance parameter, Exposure value

0

This study assessed inhalation exposure to particulate matter (PM₁)-bound mercury (Hgp) and PM₁-bound polycyclic aromatic hydrocarbons (PAHs) among university students. For this purpose, simultaneous indoor (I) and outdoor (O) measurements were taken from two Polish technical universities (in Gliwice and Warsaw) located in distinct areas with respect to ambient concentrations and major sources of PM. The indoor geometric mean concentrations of Hgpwere found to be 1.46 pg·m-3and 6.38 pg·m-3in Warsaw and Gliwice, while the corresponding outdoor concentrations were slightly lower at 1.38 pg·m-3and 3.03 pg·m-3, respectively. A distinct pattern was found with respect to PAH concentrations with estimated I/O values of 22.2 ng·m-3/22.5 ng·m-3in Gliwice and 10.9 ng·m-3/11.12 ng·m-3in Warsaw. Hazard quotients (HQs) as a result of exposure to Hgpfor students aged 21 ranged from 3.47 × 10-5(Warsaw) to 1.3 × 10-4(Gliwice) in terms of reasonable maximum exposure (RME). The non-cancer human health risk value related to Hgpexposure was thus found to be below the acceptable risk level value of 1.0 given by the US EPA. Daily exposure values for lecture hall occupants, adjusted to the benzo(a)pyrene (BaP) toxicity equivalent (BaPeq), were 2.9 and 1.02 ng·m-3for the Gliwice and Warsaw students, respectively. The incremental lifetime cancer risk (ILCR) values with respect to exposure to PM₁-bound PAHs during the students' time of study were 5.49 × 10-8(Warsaw) and 1.43 × 10-7(Gliwice). Thus, students' exposure to indoor PAHs does not lead to increased risk of lung cancer.

Concepts: Polycyclic aromatic hydrocarbon, United States Environmental Protection Agency, Particulate, Aromaticity, Hazard, Air pollution, Naphthalene, Exposure value

0

Our previous work suggests that 2 colors can be consolidated into visual short-term memory (VSTM) in parallel without a loss of memory precision, whereas consolidation of 2 orientations is performed in a strictly serial manner. Those experiments compared VSTM performance for simultaneously and sequentially presented stimuli. However, there is still controversy about whether the bandwidth for consolidation is determined by the type of information. To further investigate this issue, here we measured electroencephalography while participants attempted to consolidate 1, 2 or 4 simultaneously presented colors (Experiment 1) or orientations (Experiment 2) under limited presentation times. We used the contralateral delay activity (CDA) as an electrophysiological marker of the number of items that were consolidated. For colored stimuli, the CDA amplitude increased between set-size 1 and 2 but did not further increase for set size 4. By contrast, for orientation, the CDA amplitude remained at the set size 1 amplitude as set size increased to 2 or 4 items. Furthermore, in a long exposure duration (300 ms) condition that did not limit the consolidation process, the CDA amplitude pattern indicated that VSTM capacity is limited to about 3 colored items and about 2 orientation items in our paradigm. Thus, the CDA effects observed in the short presentation time was not limited by VSTM storage, but rather by consolidation. These results are consistent with our previous behavioral research and suggest that the bandwidth of VSTM consolidation is determined by the stimulus feature. (PsycINFO Database Record

Concepts: Neuroscience, Memory, Electroencephalography, Short-term memory, Exposure, Shutter speed, Visual short term memory, Exposure value

0

This study proposes a novel concept of actuator-driven frame-by-frame intermittent tracking for motion-blur-free video shooting of fast-moving objects. The camera frame and shutter timings are controlled for motion blur reduction in synchronization with a free-vibration-type actuator vibrating with a large amplitude at hundreds of hertz so that motion blur can be significantly reduced in free-viewpoint high-frame-rate video shooting for fast-moving objects by deriving the maximum performance of the actuator. We develop a prototype of a motion-blur-free video shooting system by implementing our frame-by-frame intermittent tracking algorithm on a high-speed video camera system with a resonant mirror vibrating at 750 Hz. It can capture 1024 × 1024 images of fast-moving objects at 750 fps with an exposure time of 0.33 ms without motion blur. Several experimental results for fast-moving objects verify that our proposed method can reduce image degradation from motion blur without decreasing the camera exposure time.

Concepts: Sound, Exposure, Photography, Shutter speed, Camera, Science of photography, Exposure value, Frame rate

0

Despite their remarkable properties, metal-organic frameworks (MOFs) present vulnerable structures that are sensitive to moisture; therefore, their application to real field situations is challenging. Herein, an O2 plasma technique was introduced as a new method for the activation and protection of porosity in HKUST-1. In an unprecedented manner, O2 plasma-treated HKUST-1 retains its porosity after a long exposure to moisture as compared to pristine HKUST-1. Porosity retention was examined by N2 adsorption/desorption measurements of non-activated HKUST-1 after exposure to moisture.

Concepts: Exposure, Science of photography, Exposure value

0

To what extent are shifts of attention driven by encoding of visual-spatial landmarks, associated with useful locations, or by encoding of environmental cues that act as symbolic representations, providing information about where to look next? In Experiment 1 we found that when cues were presented with a long exposure time (300 ms) attention shifts were driven by the symbolic identity of cue stimuli, independently of their visual-spatial (landmark) features; but when cues were exposed very briefly, (66 ms), attention shifts were independent of symbolic information, and were driven instead by visual landmark features. This unexpected finding was interpreted in terms of the transient and sustained response characteristics of the M-cell and P-cell inputs to the dorsal and ventral visual streams, respectively, and informed our theoretical proposal that attentional effects elicited by visual-spatial landmarks may be driven by dorsal stream (“where pathway”) encoding; while attentional effects driven by the symbolic identity of cues may be driven by ventral stream (“what pathway”) encoding. Detailed predictions derived from this proposal, and based on distinct physiological properties of the 2 visual streams were tested and confirmed in Experiments 2-6. Our results suggest that a 2-process view of attention shifting can be integrated with dual-stream models of vision. According to this unified theory: (a) Landmarks associated with visually useful locations elicit rapid, nonconscious shifts of attention, via nonsemantic, dorsal visual stream encoding of their features and spatial relationships; (b) Slower, endogenous shifts of attention are elicited by ventral visual stream encoding of symbolic-semantic information. (PsycINFO Database Record

Concepts: Attention, Neuroscience, Experiment, Exposure, Shutter speed, Neural mechanisms behind shifts of attention, Exposure value, Two Streams hypothesis

0

In the present study, the occurrence, concentrations, and distribution of organophosphate esters (OPEs) were studied in surface soil and street dust samples collected from different sites of Chongqing, a metropolitan city in western China. Furthermore, nondietary daily intakes (DIs) of OPEs only through dust ingestion absorption were assessed between toddlers and adults. The ∑OPEs contents ranged from 10.1 to 315 ng/g dw and from 348 to 1369 ng/g dw in surface soil and street dust samples, respectively, with tris (2-butoxyethyl) phosphate (TBOEP), the predominant OPEs in surface soil, whereas tris (chloroethyl) phosphate (TCEP) occupied a relatively high proportion in street dust samples. The mobility of TCEP and tris (2-chloroisopropyl) phosphate (TCIPP) to deeper soil zones with seepage water may play a role in decreasing contents of both compounds in surface soil. Considerably different patterns of pairwise correlations of six OPEs congeners were observed between surface soil and street dust, which could largely relate to the complicated environmental process for tris (1,3-dichloroisopropyl) phosphate (TDCIPP) and TCIPP in surface soil. Analogous sources between surface soil and street dust have been identified through principal component analysis. Compared with adults, the toddlers were more vulnerable to OPEs intake, according to the estimated DI values. For both toddler and adult groups, the estimated exposure values for all OPEs were several orders of magnitude lower than the reference dose (RfD), not suggesting the potential risk to human health.

Concepts: Soil, Dose, Principal component analysis, Singular value decomposition, Intake, Toddler, Exposure value, China Western Development