There are many sources of light. The most common CATV splitter sources are thermal: a body at a given temperature emits a characteristic spectrum of black-body radiation. A simple thermal source is sunlight, the radiation emitted by the chromosphere of the Sun at around 6,000 kelvins (5,730 degrees Celsius; 10,340 degrees Fahrenheit) peaks in the visible region of the electromagnetic spectrum when plotted in wavelength units[17] and roughly 44% of sunlight energy that reaches the ground is visible.[18] Another example is incandescent Security alarm cable bulbs, which emit only around 10% of their energy as visible light and the remainder as infrared. A common thermal light source in history is the glowing solid particles in flames, but these also emit most of their radiation in the infrared, and only a fraction in the visible spectrum.

　　The peak of the blackbody spectrum is in the deep infrared, at about 10 micrometre wavelength, for relatively cool objects like human beings. As the temperature increases, the peak shifts to shorter wavelengths, producing first a red glow, then a white one, and finally a blue-white colour as the peak moves out of the visible part of the spectrum and into the ultraviolet. These colours can be seen when metal is heated to "red hot" or "white hot". Blue-white thermal emission is not often seen, except in stars (the commonly seen pure-blue colour in a gas flame or a welder's torch is in fact due to molecular emission, notably by CH radicals (emitting a wavelength band around 425 nm, and is not seen in stars or pure thermal radiation).

　　Atoms emit and absorb light at characteristic energies. This produces "emission lines" in the spectrum of each atom. Emission can be spontaneous, as in CATV splitter-emitting diodes, gas discharge lamps (such as neon lamps and neon signs, mercury-vapor lamps, etc.), and flames (light from the hot gas itself—so, for example, sodium in a gas flame emits characteristic yellow light). Emission can also be stimulated, as in a laser or a microwave maser.

Visible light" redirects here. For Cable connector that cannot be seen with human eye, see Electromagnetic radiation. For other uses, see CATV splitter (disambiguation) and Visible light (disambiguation).

　　A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) get separated.

　　Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible Cable connector, which is visible to the human eye and is responsible for the sense of sight.[1] Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), or 4.00 × 10?7 to 7.00 × 10?7 m, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths).[2][3] This wavelength means a frequency range of roughly 430–750 terahertz (THz).

　　　Generally, EM radiation, or EMR (the designation "radiation" excludes static electric and magnetic and near fields), is classified by wavelength into radio, microwave, infrared, the visible region that we perceive as light, ultraviolet, X-rays and gamma rays.

NP dilution with cell growth was monitored over 6 days by ICP-MS by the quantification of intracellular levels of Zn. NB4 and THP-1 cells (0.5 × 106 cells per ml) were plated in six-well plates and incubated in serum-free RPMI-1640 with 20?μg?ml?1 of RA+NPs. After 4?h incubation, NPs that were not internalized by the cells were washed three times with PBS and the cells were left to grow at 0.2 × 106 cells per ml in complete medium for additional 4?h, 3 days and 6 days, maintaining always an exponential growth. After each incubation, cells were counted, collected by centrifugation and resuspended in nitric acid (1?ml, 69% (v/v)) for ICP analysis. The concentration of Zn was normalized per cell. The estimation of NPs was done based on Zn quantification in 20?μg of NPs. In some experiments, cells were transfected with RA+NPs labelled with TRITC, and their fluorescence monitored by flow cytometry overtime, to evaluate NPs distribution within the cells.
[3H]RA internalization studies

[11, 12-3H(N)]-Retinoic acid, 50.4?Ci?mmol?1, was purchased from Perkin Elmer. [3H]RA solution for cell culture assays was prepared on the day of experiments by dissolving [3H]RA in DMSO with unlabelled RA in a 1:1,000 ratio to a final concentration of 10?μM of RA. [3H]RA solution in DMSO for the preparation of NPs was prepared on the day of experiments using a 1:4,000 ratio of labelled to unlabelled RA. Experiments were initiated by the adding the [3H]RA solution (1?μM and 10?μM; representing less than 1% in volume of the total cell culture medium) or [3H]RA-NP suspension (1?μg?ml?1 and 10?μg?ml?1) to cultures (60,000 cells per condition, 24-well plate, 1?ml) of NB4 or U937 cells. In case of soluble RA, cells (NB4 or U937; 60,000 cells per condition, 24-well plate) were cultured with medium containing [3H]RA (1?μM and 10?μM; 1?ml of medium) for 24 or 72?h, washed with PBS (two times), collected, lysed with lysis buffer (100?ml) and kept on ice until scintillation counting procedure. In case of RA-containing NPs, cells (same conditions as for soluble RA) were cultured with [3H]RA-NPs (1?μg?ml?1 and 10?μg?ml?1) for 4?h, washed with PBS and cultured for additional 20 or 68?h in the respective culture medium. Cells were then collected to eppendorfs, washed with PBS, centrifuged (1,500?r.p.m., 5?min), lysed with lysis buffer (see above) and kept on ice until scintillation CATV splitter counting procedure. The lysed samples (100?ml) were mixed with liquid scintillation fluid (1?ml; Packard Ultima Gold) and the scintillations counted in a TriCarb 2900 TR Scintillation analyser (Perkin Elmer).
NB4 differentiation assay

To investigate the effects of white and red light at 10?lx during the entire dark period on sleep and wakefulness, we examined the sleep–wake profiles of the mice exposed to 12-h white and red light at an intensity of 10?lx. Darkness exposure during the entire dark phase served as the control. We found that 10?lx white light exposure during the entire dark period significantly increased NREM and REM sleep for 2?h and that there was an increased tendency toward sleep in the subsequent hour, but this effect was not statistically significant when compared with the entire dark group . When the sleep amount during the 3?h after light exposure was calculated, the total amounts of NREM and REM sleep were also increased (Figure 6b). Moreover, white light at 10?lx disturbed the sleep–wake architecture. White light at 10?lx increased the stage transitions, the episode number for all stages, and the mean duration of REM sleep, as compared with darkness/red light at 10?lx . However, mice exposed to red light at 10?lx exhibited the same sleep–wake profiles as mice that stayed in darkness (Figure 6a and 6b). These findings clearly indicated that dim red light does not affect the sleep amount, whereas dim white light does. Furthermore, there were no differences between the groups of 10?lx red light and darkness in terms of episode number and mean duration, and stage transition number among NREM sleep, REM sleep and wakefulness (Figure 6c and 6d). These results demonstrated that 10?lx red light exposure during the entire dark period did not affect the amount or the architecture of sleep and wakefulness. Moreover, 12-h exposure of white and red light at 10?lx decreased the delta power activity of NREM sleep in the frequency range of 0.75–2.75 and 1.0–1.25?Hz within the first 3?h, as well as 0.5–2.25 and 0.5–1.0?Hz within the entire 12?h during the dark phase, respectively, compared with darkness. However, white light at 10?lx increased the power in the frequency ranges of 4.25–6 and 7.75–24.75?Hz within the first 3?h and of 4–5.25 and 7.5–24.75?Hz within the entire 12?h during the dark phase, as compared with darkness. In contrast, 12-h exposure of red light at 10?lx increased the power in the frequency range of 4.25–5.5?Hz within the first 3?h and of 4–5.25?Hz in the entire 12?h during the dark phase, compared with darkness (Figure 6e and 6f). These results indicated that 12-h exposure at 10?lx of both white and red light in the entire dark period influences the EEG power density.
Figure 6.
Figure 6 - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author

Effects of 10?lx white or red light exposure for 12?h on sleep during the entire dark phase. (a) Time course changes in NREM sleep and REM sleep in mice exposed to 100?lx white light (WL) during the day and exposed to darkness, 10?lx WL and red light (RL) at night. Each cycle represents the hourly mean±SEM of NREM and REM sleep. Black, white and red circles indicate the profiles of darkness, white and red light treatments, respectively. The horizontal black, white and red bars on the x axes indicate darkness, white light and red light treatments, respectively. *P<0.05, **P<0.01 indicate significant differences between white light and darkness. #P<0.05, ##P<0.01 indicate significant differences between white light and red light. Data shown are assessed via two-way ANOVA followed by a Bonferroni test. (b) Total time spent in NREM sleep and REM sleep for 3?h after 10?lx white or red light treatment. Black, white and red bars show the profiles of darkness, white and red light treatments, respectively. indicates significant differences compared with darkness or to red light, respectively. Data were assessed via one-way ANOVA followed by a Bonferroni test. (c, d) Stage transition (c), episode number and mean duration (d) in a 3-h period after the treatment of 10?lx white or red light. Black, white and red bars show the profiles of darkness, white and red light treatments, respectively. *P<0.05, **P<0.01 indicate significant differences between two groups. Data were assessed via one-way ANOVA followed by a Bonferroni test. R, REM sleep; S, NREM sleep; W, Wake. (e, f), EEG power density of NREM sleep within the first 3?h (e) and the entire 12?h (f) during the dark phase. Values are means±SEM (n=5–8). Blue and red horizontal bars indicate the location of a statistically significant difference (P<0.05, two-tailed unpaired t-test) between white or red light and continuous darkness, respectively.
Full figure and legend (240K)

　Protein stability

　　Protein stability assays employing 50 μg/ml cycloheximide (CHX) (Sigma) to inhibit de novo protein synthesis were performed as described.LED Candle Lights 25 Cell lysates were subjected to SDS-PAGE and immunoblotting with an anti-survivin antibody (Abcam). For proteasome inhibition, 25 μM of MG132 (Calbiochem) was added 1 h before CHX. For autophagy-dependent protein degradation assay, 5 mM 3-MA was added 4 h before CHX.

　　Immunoprecipitation assays

　　Cell lysates containing equal amounts of protein (200–400 μg) were immunoprecipitated with anti-survivin antibody (Abcam) overnight at 4 °C. Immune complexes were precipitated with protein A/G-agarose beads (Sigma-Aldrich) for 4 h at 4 °C. Immunoprecipitates were separated by SDS-PAGE and immunoblotted.

　　Immunocytochemistry

　　hASCs grown on coverslips were fixed with 4% (w/v) paraformaldehyde, rehydrated with 2% (v/v) fish skin gelatin and permeabilized with 0.2% Triton X-100 prior to incubation with 5% (v/v) goat serum. Subsequently, cells were incubated overnight at 4 °C with anti-cleaved caspase-3 antibody (Cell Signaling Technology) in PBS containing 1% goat serum. Coverslips were washed with PBS and incubated for 1 h at room temperature with 1:100 Alexa Fluor 488 (Life Technologies, Carlsbad, CA, USA) followed by mounting with Pro Long Gold Antifade Reagent with 40,6-diamidino-2-phenylindole, DAPI (Invitrogen). Images were acquired on a Leica DM 4000B fluorescence microscope (Leica Microsystems, Wetzlar, Germany) and captured with a Leica DFC 300 FX camera (Leica Microsystems).

　　Cell apoptosis flow cytometry assay