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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.

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.

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.

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.

Consumers are demanding foods with high sensory and nutritional quality including a higher content of compounds that help maintain good health. Given this scenario, new technologies are emerging to produce fresh salads that have the characteristics currently in demand. Shade nettings or photoselective filters on fruit and vegetable crops are a technology that provides protection, modifies the light spectrum resulting in a higher accumulation of antioxidant compounds, making them more desirable to consumers. The objective of this study was to compare the effect of shade netting on the fresh quality parameters of baby leaf spinach grown in a hydroponic system at harvest and after a period of 10 days at 4 °C. By using different shade netting colors, the average photosynthetic photon flux density (PPFD) that reaches the plants was modified during the growing period of baby leaf spinach (red: 118.35 μmol m−2 s−1; blue:117.96 μmol m−2 s−1; gray: 63.18 μmol m−2 s−1 and control without shade nettings: 278.12 μmol m−2 s−1). At harvest, baby leaf spinach grown under the red shade netting reached the highest yield. However, with the blue filter, leaves showed a value of 9.3 % dry weight, significantly higher than the values from red and gray filters with values of 7.3 and 6.3 %, respectively. The phenolic compound contents reached significantly higher values of 485.5 mg gallic acid equivalent (GAE) per 100 g−1 FW for the baby leaf spinach grown under the red filter compared to the blue, gray and control filters with values of 472.5; 387.6 and 316.5 mg GAE per 100 g−1 FW, respectively. The antioxidant capacity was significantly higher under the red filter. The sensory quality parameters indicated that spinach grown under color filters did not show off-flavors and maintained its turgidity and appearance at harvest. In the postharvest period, baby leaf spinach grown under red filter maintained the highest total phenol content and antioxidant activity after 10 days at 4 °C with similar appearance and turgidity as the control.

Introduction Virtual chromoendoscopy is used to enhance surface patterns and colour differences. One type of virtual chromoendoscopy is the Fuji Intelligent Colour Enhancement (FICE). Although widely applied in conventional endoscopy, data on FICE application in capsule endoscopy are limited. Furthermore, the validity of Blue filter (feature of RAPID® software) has not been examined. Aim/s We aimed to qualitatively evaluate the use of FICE and Blue filter enhancement, in images of lesions obtained during small bowel capsule endoscopy, comparing them with similar, conventional (white light) images. Methods A total of 167 images (6 different lesion categories) obtained from 200 capsule endoscopy examinations. Two gastroenterologists examined the images with white light, FICE and Blue filter in regards to the visibility of blood vessels, the contrast of the mucosal surface, and the demarcation of lesion borders. The agreed scores were: improved, similar, worse. Inter-observer agreement was calculated. Results For all lesion categories, Blue filter provided image improvement (compared to white light) in 83%, (inter-observer agreement: 0.786). With FICE 1, improvement was observed in 34%, worse image in 55.9%, (inter-observer agreement: 0.646). With FICE 2, improvement was observed in 8.6%, worse in 77.5%, (inter-observer agreement: 0.617). With FICE 3, improvement was seen in 7.7%, worse in 79.9% (inter-observer agreement: 0.669). Conclusion Comparing with FICE, Blue filter offers better image enhancement in capsule endoscopy.

Neurophysiological recordings have shown that activity of magnocellular neurons may be reduced by red backgrounds. This has led some researchers to use red light, or red filters, in attempts to determine the magnocellular contribution to psychophysical tasks. This requires that red light not affect parvocellular neurons, or at least that it is possible to control for the effect on the parvocellular system by using other colors. The present report investigates these assumptions by calculating the effect of red, green, and blue filters on the three cone pigments and on the four parvocellular color-opponent cell mechanisms. It is found that a red filter has a large effect on the long- and middle-wavelength cone pigments and on the red–green color-opponent mechanisms. A green filter, on the other hand, has little effect. A blue filter has a fairly pronounced effect but this effect is distinctly different from that of the red filter. These results indicate that one ought not rely upon red light to isolate magnocellular activity in psychological experiments. The results also indicate that it is difficult to use colors other than red to control for the effect of this color on the parvocellular system.

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.

For the lacrimal surgeon, fluorescein instilled in the palpebral aperture, and combined with the use of blue filters, can assist office assessment of lacrimal drainage by nasal endoscopy. The fabrication of a separate blue filter attachment for nasal endoscopes, however, is expensive. Inexpensive, heat-stable blue filter discs were sourced from a manufacturer of fiberoptic instruments in Sydney, Australia. These discs can be made in various sizes suitable for standard battery-powered, portable nasal endoscopes. The discs were used in the postoperative assessment of a patient with lacrimal drainage-related pathology. They were easy to use and provided suitable wavelength transmission for improved assessment of fluorescein drainage through the lacrimal system.

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.

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.

Summary Sporulation of Botrytis cinerea was studied in vitro under various filters and polyethylene co-polymer (PE) sheets. It was found that continuous darkness blocked sporulation completely. Sporulation was inhibited by reduced ultraviolet (u.v.) radiation. Almost total inhibition of sporulation was also found when cultures were grown under a blue filter. The reduction of spore formation was negatively related to the ratio of transmitted blue/u.v. light. The possibility of using this effect to control the incidence of Botrytis cinerea in greenhouses is discussed. A brief report has been published (Reuveni, Raviv, Allingham & Bar, 1988).

A glass filter is described which enables the colour temperature of lamps to be measured, using standard lamps which operate at lower colour-temperatures. The filter is yellow in colour and made from Corning 346 and 507 glasses. The method of construction is described. Colour-temperature measurements made with the glass filter agree to 4°k. with those using the blue liquid filter previously used at the laboratory. The advantages of the yellow filter over the blue filter are that the yellow filter is more stable, the colour-matching properties are better, the energy match is better for a colour match, the temperature coefficient is a fifth of that of the blue filter, and the yellow filter is placed in front of the brighter lamp, so that, for a colour match, the lamps are nearly equidistant from the photometer. The properties of glass filters made from (a) a yellow glass with Zeiss U.G.3, (b) Corning 346 with Chance O.V.2, and (c) Cobalt blue glass are mentioned.

An observation of the corona during the 7 March, 1970 eclipse through a Wollaston prism-red and blue filter combination was carried out for the purpose of confirming the prediction that the component of the K-corona with electric vector radial to the Sun is redder than the tangential component. An analysis of a portion of the resulting data seems to confirm this prediction, and also indicates that the method is useful for determining the three-dimensional configuration of the very inner corona. A three-dimensional configuration is suggested for a portion of the NE quadrant of the Sun, including the large NE streamer and an adjacent low-lying loop.

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.

During a 3-year period, 30 patients were referred for symptoms of vulvar pain characteristic of the vulvar vestibulitis syndrome. Colposcopic examination with a blue filter and pathologic biopsy revealed evidence of papillomavirus in 17 patients. Interferon alpha-2b recombinant was injected intradermally into the vestibule in a specific pattern three times weekly for 4 weeks. Fifteen women responded favorably with total absence of vulvar pain. Five women reported flu-like symptoms as a result of the injections. Patients without evidence of papillomavirus failed to respond to interferon therapy. Women with evidence of vulvar papillomavirus failed to respond to placebo but did respond to retreatment with interferon; vulvar biopsy specimens after therapy were negative. Interferon alpha-2b recombinant appears to offer an inexpensive, safe alternative to the more traumatic therapies currently recommended in the specific subset of vulvar vestibulitis patients in whom papillomavirus can be confirmed.

(1959). A blue filter technique for detecting eye movements during the autokinetic effect. Quarterly Journal of Experimental Psychology: Vol. 11, No. 2, pp. 113-114.

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