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Blue light comprises the electromagnetic spectrum between approximately 380-500 nm. The sun is the main source of blue light, although we also receive emissions of this type of light by electronic devices and artificial lighting. Changes in lighting systems and lifestyle habits have led to the questioning of exposure to blue light emitted by artificial sources as a possible health problem. Faced with this potential problem, ophthalmic lens laboratories brought to market lenses with specific treatment against hazard blue light emitted by electronic devices. In this work we measure the spectral transmittance of 6 blue filter ophthalmic lenses from 4 different laboratories, Essilor, Hoya, Shamir and Kodak. We face the transmission spectra measured with the emission spectra of 3 different electronic devices, to be able to discuss the suitability of these blue filter lenses for use with electronic devices. We conclude that the transmittance of blue filters in the maximum blue light emission range is high above 90%, and that changing the correlated color temperature of electronic devices results in a greater reduction in exposure to hazard blue light. We also found that Shamir's Blue Zero and Essilor's Eye Protect System lenses block UVA light and have low transmittance in the range of 380- 420 nm, so they would be more effective for protection against blue light outdoors than for use with electronic devices.

In this study we observed and determined the period of the eclipsing binary star EPIC 201458798, finding that its period has not changed since it was last measured and published in the Kepler catalog in 2014. We did this by developing Python code to determine the period using two independent algorithms and partially automating the search for suitable comparison stars. Our system was imaged by the 0.4m Las Cumbres Observatory telescopes in four filters. We analyzed six photometry types returned for each image from the Our Solar Siblings pipeline. Of these photometries, we found source extractor kron (sek) to be the most appropriate type for our 2x2 binned images of EPIC 201458798. Both of the period-finding algorithms we developed gave results that were not statistically different from the Kepler catalog period for the infrared, red, and visual filter images. The blue filter images were statistically different fromthe Kepler catalog period for one of our algorithms but not the other.

The non-linear filter is subject to divergence for close-range target tracking; an adaptive best linear unbiased estimation (BLUE) filter with fused range estimation is presented. After proposing the notion of predicted range, the weighted estimation of the predicted and measured ranges is used in the converted measurement model to track the target. The adaptive BLUE filtering parameters with Rayleigh range measurement are derived. Simulation results show the adaptive BLUE filter exhibits better robustness and accuracy with modest computational burden.

Background and Objectives: This retrospective consecutive case control study compares best-corrected visual acuity (BCVA), mesopic contrast sensitivity (CS), color vision, and glare between a group of eyes with blue-light-filtering intraocular lenses and another with UV-light-filtering intraocular lenses. Materials and Methods: We used Early Treatment Diabetic Retinopathy Study charts to compare BCVA, Rabin charts for mesopic CS testing, Oculus HMC Anomaloscope MR to test for chromatic discrimination, and Oculus Mesotest II to measure scotopic CS with glare. For analysis, we used descriptive statistics and compared means with parametric and non-parametric tests. The level of significance was set as α = 0.05. Results: For the group with the blue-light-filtering intraocular lens, the average results were BCVA = 0.96 (SD ± 0.09), CS = 1.78 log (SD ± 0.12), chromatic discrimination results M = 63.91 (SD ± 11.88), R = 60.07 (SD ± 7.89). For mesopic CS with glare, the group achieved on average 2.54 (SD ± 1.50) points out of 4. For the group with the UV-light-filtering intraocular lens, the average results were BCVA = 0.93 (SD ± 0.14), CS = 1.79 log (SD ± 0.13), chromatic discrimination results M = 65.38 (SD ± 17.14), R = 60.79 (SD ± 10.39). For mesopic CS with glare, this group achieved an average of 2.79 (SD ± 1.53) points out of 4. Conclusion: No significant differences (p &gt, 0.05) were found in any of the tested parameters between the analyzed groups. Slight shift in color vision was observed, although not statistically significant.

Fluorescence-guided surgery with five-aminolevulinic acid (5-ALA) is the state-of-the-art treatment of high-grade gliomas. However, intraoperative visualization of 5-ALA under blue light remains challenging, especially when blood covers the surgical field and thereby fluorescence. To overcome this problem and combine the brightness of visible light with the information delivered with fluorescence, we implemented multispectral fluorescence (MFL) in a surgical microscope, a technique that is able to project both information in real-time. We prospectively examined 25 patients with brain tumors. One patient was operated on two different lesions in the same setting. The tumors comprised: six glioblastomas, four anaplastic astrocytomas, one anaplastic oligodendroglioma, two meningiomas, 11 metastatic tumors, one acoustic neuroma, and one ependymoma. The MFL technique with a real-time overlay of fluorescence and white light was compared intraoperatively to the classic blue filter. All lesions were clearly visible and highlighted from the surrounding tissue. The pseudocolor we chose was green, representing fluorescence, with the surrounding brain tissue remaining in its original color. When blood was covering the surgical field, orientation was easy to maintain. The MFL technique opens the way for precise and clear visualization of fluorescence in real-time under white light. It can be easily used for the resection of all tumors accumulating 5-ALA. Drawbacks of classic PpIX fluorescence such as hidden fluorescence, intraoperative changes could be overcome with the presence of additional white light in MFL technique.

Aim. The objective of the study was to substantiate the rationality of using monochromatic polarized incoherent optical radiation (photochromotherapy) on the abdomen as a supplement to the standard program for the treatment of acute intestinal infections in children. Material and methods. Twenty-six children with acute intestinal infections from 6 months to 12 years old were observed during inpatient treatment. In the comparison group (n = 11), children received standard therapy, including diet therapy, rehydration, sorbents, probiotics or prebiotics, as well as indications for etiotropic drugs. In the main group, patients (n = 15) in addition to standard therapy received photochromotherapy as an effect on the abdomen with monochromatic polarized incoherent optical radiation from the Bioptron apparatus with a blue filter at a distance of 5 cm labile along the bowel. The duration of photochromotherapy was 5 minutes, the course of treatment included 4-5 sessions 1 time per day. The effectiveness of the therapy regimens used in the groups was assessed by the duration of the disease, the length of inpatient treatment, the dynamics of changes in the clinical blood test at the time of discharge. Results. The advantage of the technique with the addition of standard treatment of acute intestinal infections by photochromotherapy was established. In the main group of patients, the duration of the disease was significantly shorter (9,1±0,8 days) compared to the comparison group (10,2±1,5 days, p=0,02) against the background of a significant decrease in the severity of inflammatory manifestations in the hemogram in form of a decrease in thrombocytosis. Conclusion . The obtained data make it possible to recommend the method of photochromotherapy in the complex therapy of intestinal infections of various etiologies in children older than 6 months.

In manoeuvring target tracking, a primary tradeoff is the robust tracking of manoeuvres against the accurate tracking of constant velocity (CV) motion. To achieve this goal, an interacting multiple model (IMM) algorithm fusing input estimation (IE) and best linear unbiased estimation (BLUE) filter is presented. First, the constant input assumption of IE is modified to track possible manoeuvre fluctuation. Then, an innovation sequence modification technique is proposed so manoeuvre can be detected and estimated sequentially. With improvements above, a modified input estimator (MIE) is designed to track varying manoeuvres. In view of the optimal tracking of BLUE filter for CV motion, MIE and BLUE filter are fused within IMM framework to generate an overall adaptive tracking algorithm. Simulation results reveal the proposed approach yields better accuracy for CV tracking and robustness for manoeuvre tracking.

High paralarvae mortality is a major bottleneck currently hindering the control over the lifecycle of common octopus (Octopus vulgaris Cuvier, 1797). It is believed that this problem might be related to either zoo-technical and/or nutritional aspects. The present paper is focused on the study of different zoo-technical aspects related to light conditions on the rearing of paralarvae, including the effects of polarization in prey ingestion, the use of a blue filter to simulate natural conditions, and the use of focused light to avoid reflections of the rearing tank’s walls. In the first experiment, O. vulgaris paralarvae ingestion of Artemia sp. and copepods (Tisbe sp.) was assessed under either normal or polarized light. In the second experiment, the effect of a blue filter with natural light or focused artificial light on growth and mortality was assessed over 15 days of rearing. Ingestion rate was not influenced by light polarization. Nonetheless, a significantly higher ingestion of Artemia sp. with respect to copepods was observed. The blue filter promoted the use of natural light conditions in Octopus paralarval culture, while focused light reduced the collision of the paralarvae against the walls. However, no significant differences were found in paralarval growth nor survival, SI

We have obtained imaging polarimetry of the comet C/2013 R1 (Lovejoy) with 2-Channel-Focal-Reducer Rozhen instrument at 2m Ritchey-Chr\'etien-Coud\'e telescope of the Bulgarian National Astronomical Observatory Rozhen in two dust continuum filters covering wavelength intervals clear from molecular emissions and centred at $4430\AA$ in (blue filter) and at $6840\AA$ in (red filter). In imaging mode we measured the degree of linear polarisation $17.01\pm0.09$% in the blue and $18.81\pm0.02$% in the red, which is in a very good agreement with measurements of other comets at the similar phase angle. We have also obtained polarisation maps in both filters. We found a strong correlation between the spatial distribution of the polarisation and the dust colour. Spectropolarimetry of the nucleus region shows an increase of the polarisation with wavelength, and a depolarisation in the spectral regions with gas emission lines, most noticeable in C$_2$ emission band, which shows a polarisation of $6.0\pm1.1$%., Comment: 6 pages, 8 figures, ACM2014 conference proceedings

International audience; On 12 November 2014 the European mission Rosetta succeeded in delivering a lander, named Philae, on the surface of one of the smallest, low-gravity and most primitive bodies of the solar system, the comet 67P/Churyumov-Gerasimenko (67P).Aims. The aim of this paper is to provide a comprehensive geomorphological and spectrophotometric analysis of Philae’s landing site (Agilkia) to give an essential framework for the interpretation of its in situ measurements.Methods. OSIRIS images, coupled with gravitational slopes derived from the 3D shape model based on stereo-photogrammetry were used to interpret the geomorphology of the site. We adopted the Hapke model, using previously derived parameters, to photometrically correct the images in orange filter (649.2 nm). The best approximation to the Hapke model, given by the Akimov parameter-less function, was used to correct the reflectance for the effects of viewing and illumination conditions in the other filters. Spectral analyses on coregistered color cubes were used to retrieve spectrophotometric properties.Results. The landing site shows an average normal albedo of 6.7% in the orange filter with variations of ∼15% and a global featureless spectrum with an average red spectral slope of 15.2%/100 nm between 480.7 nm (blue filter) and 882.1 nm (near-IR filter). The spatial analysis shows a well-established correlation between the geomorphological units and the photometric characteristics of the surface. In particular, smooth deposits have the highest reflectance a bluer spectrum than the outcropping material across the area.Conclusions. The featureless spectrum and the redness of the material are compatible with the results by other instruments that have suggested an organic composition. The observed small spectral variegation could be due to grain size effects. However, the combination of photometric and spectral variegation suggests that a compositional differentiation is more likely. This might be tentatively interpreted as the effect of the efficient dust-transport processes acting on 67P. High-activity regions might be the original sources for smooth fine-grained materials that then covered Agilkia as a consequence of airfall of residual material. More observations performed by OSIRIS as the comet approaches the Sun would help interpreting the processes that work at shaping the landing site and the overall nucleus.

Misalignment of the eyes can lead to double vision and visual confusion. However, these sensations are rare when strabismus is acquired early in life, because the extra image is suppressed. To explore the mechanism of perceptual suppression in strabismus, the visual fields were mapped binocularly in 14 human subjects with exotropia. Subjects wore red/blue filter glasses to permit dichoptic stimulation while fixating a central target on a tangent screen. A purple stimulus was flashed at a peripheral location; its reported color ("red" or "blue") revealed which eye's image was perceived at that locus. The maps showed a vertical border between the center of gaze for each eye, splitting the visual field into two separate regions. In each region, perception was mediated by only one eye, with suppression of the other eye. Unexpectedly, stimuli falling on the fovea of the deviated eye were seen in all subjects. However, they were perceived in a location shifted by the angle of ocular deviation. This plasticity in the coding of visual direction allows accurate localization of objects everywhere in the visual scene, despite the presence of strabismus. © 2012 the authors.

One hundred and twenty seven eyes of 127 patients were studied by means of a Kodak 47B Wratten blue gelatin filter in conjunction with the Friedmann Mark 1 visual field analyser. There were 49 patients in the normal group, 50 patients in the ocular hypertension group, and 28 patients in a group with early glaucoma. A simple scoring system did not show a useful difference between these three groups. However, use of a derived threshold value for each target group designated by the letters B to P (giving selective blue field scores) differentiated between normal subjects and those with early glaucomatous field loss. When used with a calculated upper limit of normal to give a specificity of 96%, this test had a sensitivity of 64%. Of the ocular hypertension group 22% gave abnormal results in comparison with normal persons. This simple adaptation to the Friedmann protocol may aid the ophthalmologist in the detection and confirmation of early glaucoma.

AIM: To evaluate whether virtual chromoendoscopy can improve the delineation of small bowel lesions previously detected by conventional white light small bowel capsule endoscopy (SBCE). METHODS: Retrospective single center study. One hundred lesions selected from forty-nine consecutive conventional white light SBCE (SBCE-WL) examinations were included. Lesions were reviewed at three Flexible Spectral Imaging Color Enhancement (FICE) settings and Blue Filter (BF) by two gastroenterologists with experience in SBCE, blinded to each other’s findings, who ranked the quality of delineation as better, equivalent or worse than conventional SBCE-WL. Inter-observer percentage of agreement was determined and analyzed with Fleiss Kappa (k) coefficient. Lesions selected for the study included angioectasias (n = 39), ulcers/erosions (n = 49) and villous edema/atrophy (n = 12). RESULTS: Overall, the delineation of lesions was improved in 77% of cases with FICE 1, 74% with FICE 2, 41% with FICE 3 and 39% with the BF, with a percentage of agreement between investigators of 89% (k = 0.833), 85% (k = 0.764), 66% (k = 0.486) and 79% (k = 0.593), respectively. FICE 1 improved the delineation of 97.4% of angioectasias, 63.3% of ulcers/erosions and 66.7% of villous edema/atrophy with a percentage of agreement of 97.4% (k = 0.910), 81.6% (k = 0.714) and 91.7% (k = 0.815), respectively. FICE 2 improved the delineation of 97.4% of angioectasias, 57.1% of ulcers/erosions and 66.7% of villous edema/atrophy, with a percentage of agreement of 89.7% (k = 0.802), 79,6% (k = 0.703) and 91.7% (k = 0.815), respectively. FICE 3 improved the delineation of 46.2% of angioectasias, 24.5% of ulcers/erosions and none of the cases of villous edema/atrophy, with a percentage of agreement of 53.8% [k = not available (NA)], 75.5% (k = NA) and 66.7% (k = 0.304), respectively. The BF improved the delineation of 15.4% of angioectasias, 61.2% of ulcers/ erosions and 25% of villous edema/atrophy, with a percentage of agreement of 76.9% (k = 0.558), 81.6% (k = 0.570) and 25.0% (k = NA), respectively. CONCLUSION: Virtual chromoendoscopy can improve the delineation of angioectasias, ulcers/erosions and villous edema/atrophy detected by SBCE, with almost perfect interobserver agreement for FICE 1.

SUMMARY Fifty eyes of fifty patients with ocular hypertension had their visual fields tested on a Friedmann Mark 1 field ana­ lyser whilst wearing a Wratten 47B blue filter in a spec­ tacle frame. All had normal visual fields to a white stimulus. Use of a scoring system with the blue field iden­ tified 11 patients (22 %) with ocular hypertension as abnormal. The scores from this subgroup were indistin­ guishable from a group of subjects with early glaucoma­ tous field loss, whilst the remaining scores were similar to normal subjects. These two subgroups of ocular hyper­ tensive patients were similar in age and intraocular pres­ sure. The use of a blue filter in front of the eye may offer a simple test to identify a subgroup of patients with ocular hypertension who are at increased risk of developing field

tip of the tonometer prism only when the to­ nometer prism is almost fully pushed into the body of the tonometer by contact with the patient's eye. Additionally, the cobalt-blue fil­ ters covering the light sources are easily dis­ lodged, further reducing the amount of blue light to excite fluorescence. In clinical use the illumination of the tonometer is so dim that the room lights must be dimmed in order to use the instrument.1 The poor illumination of the to­ nometer head may produce hypofluorescence of the fluorescein in the precorneal tear film, causing underestimation of the intraocular pressure.2"4 One of us (R.S.) modified the Mark II model of Perkins tonometer to provide substantially increased illumination of the tonometer head. The two 2.7 May lights that usually illuminate the tonometer head were replaced with two Welch-Allyn 3100 halogen bulbs. Blue filter caps to cover the halogen bulbs were fashioned from aluminum tubing and the same type of blue filter as the Perkins tonometer (Eastman Kodak Wratten 47B). The angle of the light sources was unchanged from the original de­ sign. This modification is shown in the Figure. A widening of the case at the site of the exit of the halogen bulbs was made to accommodate the increased diameter of the new light sources. The two 1.35-V mercury cells or four 1.5 V AA batteries that normally power the Perkins to­ nometer were replaced by a 3.5-V Welch-Allyn nickel-cadmium battery to match the voltage of the halogen bulbs. With these modifications the brightness of the illumination of the tonometer head is mark­ edly increased. The fluorescent ring produced by tonometer-corneal contact is easily seen without dimming the room lights and is bright­ er than that seen by using a slit-lamp mounted tonometer. The tonometer head position has less of an effect on the brightness of the fluores­ cent rings. These changes eliminate underillumination of the tonometer prism and minimize any underestimation of the intraocular pres­ sure, that might occur from underillumination, making the Perkins tonometer easier to use and more accurate.

An Indian expedition to Antarctica (to the coastal base Maitri) in the 1989/90 summer made observations of the Sun to study the evolution and decay of supergranules, an experiment which benefited greatly from uninterrupted sessions of a few days. The instrument comprised a heliostat, a 1.2 Å bandwidth blue filter, and a 10 cm aperture lens of about 3 metre focal length with recording on film. During January and February, one continuous period of more than 100 hours completely clear sky occurred, during which the transparency of the atmosphere was excellent. However, at times the seeing was a little poor. More than 2500 photographs were made at 10 minute intervals, as well as some at shorter intervals for studying the evolution of other solar features such as flares.

The paper discusses results of an attempt to restore two blurred pictures of Ganymede taken by Pioneer 10 through a blue filter and a red filter. The mathematical formulation of the restoration problem is outlined, it is noted that both conventional linear filtering and the maximum-entropy algorithm were employed as restoration techniques, and the two methods are described. The original blurred pictures are reproduced along with the two restorations of each image. The restored images are found to exhibit some mare-like features as well as a few large bright rings, possibly ice ridges. The results obtained with the two restoration techniques are compared, and it is concluded that the maximum-entropy method is more advantageous than linear methods in applications to moderately extended images.

Patients with the sensorimotor induction syndrome in unilateral disequilibrium often have an impairment of various qualities of sensibility on the homolateral side of the body. Utilizing measures of the tactile two point discrimination threshold the present study indicated that this impairment is systematically influenced by head posture, eye conditions, and colored light. Turning the head to the homolateral side, seeing with the homolateral eye alone, or placing a red filter before the eye, caused a clear rise in the tactile two point discrimination threshold. In contrast, turning the head to the contralateral side, seeing with the contralateral eye alone, or placing a blue filter before the open eye, caused a lowering of the threshold. These results indicate that the variability of the two point discrimination corresponds with the basic neurodynamic rules of sensorimotor induction which were found to be valid for other sensory functions. Of clinical importance is the confirmation that the impairment in these patients is not result of a primary lesion of the sensory pathways, but is a secondarily induced phenomenon.

1. The threshold value for light has been used as a measure of the sensitivity of the eye. 2. When any light shines on the retina the sensitivity, even of another part, is decreased considerably to short, but much less to long, wave-lengths. This is the familiar adaptation phenomenon. 3. When two lights shine on the same part of the retina there is a further decrease in sensitivity which has a peculiar spectral distribution; namely, that long wave-lengths decrease the sensitivity to all shorter ones, whilst short wave-lengths have comparatively little effect on longer ones. 4. A region of the retina about 30° to the nasal side of the right eye differs from the fovea (a) in the greater degree of light adaptation, so that even the long wave-lengths are noticeably affected; (b) in the sensitivity to longer wave-lengths being somewhat more affected by short ones, when the two shine on the same region of the retina. 5. The bearing of the above results is discussed in relation to theories of colour vision. It is suggested that the most probable explanation is that colour discrimination is due to colour screens in front of certain of the receptors. 6. The results show why a blue screen is the best to protect the eyes from excessively bright lights. It would be interesting to know to what extent “glare” is particularly due to the longer wave-lengths. A blue filter on the wind-screen of a motor-car will protect the eyes from the direct rays of bright head-lights, whilst allowing one to see the road past the edge of the filter; thus use may be made of the sensitivity to the light of longer wave-lengths, which these experiments show are not much affected by exposure to short wave-lengths.

The gradual disappearance of the yellow colour of ferricyanide with the addition of vanadyl ions in alkaline medium has been made the basis of the quantitative determination of both vanadium and ferricyanide. The colorimetric titrations were carried out with the aid of a Hilger Spekker Absorptiometer with a blue filter having maximum transmission in the range of 450–500 mμ. It is shown that the accuracy of the results compares favourably with those obtained by other standard procedures.

OUR earlier starch-gel electrophoretic zymograms1, obtained with 1-leucyl-β-naphthylamide (LBNA) substrate, revealed a single leucine aminopeptidase (LAP) zone for human serum. The substitution of alanyl-β-naphthylamide (ABNA) substrate now consistently reveals, within the diffuse trail behind the primary zone, an additional less-intense zone (Fig. 1a), detectable also for some sera by LBNA. Occasional sera give three or more zones; and one chronic pancreatitis serum has given a remarkable zymogram with five zones which, when observed through a suitable blue filter (Dupont No. 9 plastic ‘Varigam’ filter), can be distinguished as eight zones (Fig. 1b).

A device is described for producing homogeneous illumination. Use is made of internal reflections within a rectangular box.