Abstract: We propose a widegap II–VI semiconductor alloy, MgxZn1−xO, for the fabrication of heteroepitaxial ultraviolet light emitting devices based on ZnO. The c-axis oriented MgxZn1−xO films were epitaxially grown by pulsed laser deposition on ZnO epitaxial films and sapphire (0001) substrates using ceramic targets. Solid solution films were prepared with Mg content up to x=0.33, achieving a band gap of 3.99 eV at room temperature. MgO impurity phase segregated at x⩾0.36. Lattice constants of MgxZn1−xO films changed slightly (∼1%), increasing in a axis and decreasing in c-axis direction with increasing x. These films showed ultraviolet photoluminescence at energies from 3.36 (x=0) to 3.87 eV (x=0.33) at 4.2 K.

Abstract: Background Vitamin D deficiency is a major risk factor for bone loss and fracture. Although hypovitaminosis D has been detected frequently in elderly and housebound people, the prevalence of vitamin D deficiency among patients hospitalized on a general medical service is unknown. Methods We assessed vitamin D intake, ultraviolet-light exposure, and risk factors for hypovitaminosis D and measured serum 25-hydroxyvitamin D, parathyroid hormone, and ionized calcium in 290 consecutive patients on a general medical ward. Results A total of 164 patients (57 percent) were considered vitamin D–deficient (serum concentration of 25-hydroxyvitamin D, <15 ng per milliliter), of whom 65 (22 percent) were considered severely vitamin D–deficient (serum concentration of 25-hydroxyvitamin D, <8 ng per milliliter). Serum 25-hydroxyvitamin D concentrations were related inversely to parathyroid hormone concentrations. Lower vitamin D intake, less exposure to ultraviolet light, anticonvulsant-drug therapy, renal dialysis, nep...

Abstract: Whereas the photodynamic therapy (PDT) of cancer has recently shown rapid clinical acceptance, photodynamic antimicrobial chemotherapy (PACT)--which predates the related cancer regimen--is not widely appreciated. Like PDT, PACT utilizes photosensitizers and visible or ultraviolet light in order to give a phototoxic response, normally via oxidative damage. Currently, the major use of PACT is in the disinfection of blood products, particularly for viral inactivation, although more clinically-based protocols are being developed, e.g. in the treatment of oral infection. The technique has been shown to be effective in vitro against bacteria (including drug-resistant strains), yeasts, viruses and parasites. A wide range of photosensitizers, both natural and synthetic, is available with differing physicochemical make-up and light-absorption properties. PACT is proposed as a potential, low-cost approach to the treatment of locally occurring infection.

Abstract: Objective: This study tests the hypothesis that stress reduction methods based on mindfulness meditation can positively influence the rate at which psoriasis clears in patients undergoing phototherapy or photochemotherapy treatment. Methods: Thirty-seven patients with psoriasis about to undergo ultraviolet phototherapy (UVB) or photochemotherapy (PUVA) were randomly assigned to one of two conditions: a mindfulness meditation-based stress reduction intervention guided by audiotaped instructions during light treatments, or a control condition consisting of the light treatments alone with no taped instructions. Psoriasis status was assessed in three ways: direct inspection by unblinded clinic nurses; direct inspection by physicians blinded to the patient's study condition (tape or no-tape); and blinded physician evaluation of photographs of psoriasis lesions. Four sequential indicators of skin status were monitored during the study: a First Response Point, a Turning Point, a Halfway Point, and a Clearing Point. Results: Cox-proportional hazards regression analysis showed that subjects in the tape groups reached the Halfway Point [p — .013) and the Clearing Point (p = .033) significantly more rapidly than those in the no-tape condition, for both UVB and PUVA treatments. Conclusions: A brief mindfulness meditation-based stress reduction intervention delivered by audiotape during ultraviolet light

Abstract: Photorefractive materials are being widely investigated for applications in holographic data storage1. Inhomogeneous illumination of these materials with an optical interference pattern redistributes charge, builds up internal electric fields and so changes the refractive index. Subsequent homogeneous illumination results in light diffraction and reconstructs the information encoded in the original interference pattern. A range of inorganic and organic photorefractive materials are known2, in which thousands of holograms of high fidelity can be efficiently stored, reconstructed and erased. But there remains a problem with volatility: the read-out process usually erases the stored information and amplifies the scattered light. Several techniques for ‘fixing’ holograms have been developed3,4,5,6, but they have practical disadvantages and only laboratory demonstrators have been built7,8,9,10. Here we describe a resolution to the problem of volatility that should lead to the realization of a more practical system. We use crystals of lithium niobate — available both in large size and with excellent homogeneity — that have been doped with two different deep electron traps (iron and manganese). Illumination of the crystals with incoherent ultraviolet light during the recording process permits the storage of data (a red-light interference pattern) that can be subsequently read, in the absence of ultraviolet light, without erasure. Our crystals show up to 32 per cent diffraction efficiency, rapid optical erasure of the stored data is possible using ultraviolet light, and light scattering is effectively prevented.

Abstract: Variation in the extent of sexual dimorphism among bird species is traditionally attributed to differences in social mating system. However, there are many different forms of dimorphism among birds, and not all of them show an obvious correlation with social mating system. For example, recent work has shown that many highly polygamous species are, in fact, monomorphic, whereas many putatively monogamous species are dimorphic. In this paper we break up sexual dimorphism into subcomponents and then use comparative analyses to examine the pattern of covariation between these subcomponents and various aspects of sexual, social, and par ental behaviour. Our first finding is that size dimorphism and plumage-colour dimorphism do not show the same pattern of covariation. Differences in size dimorphism are associated with variation in social mating system and sex differences in parental care, whereas differences in plumage-colour dimorphism are associated with variation in the frequency of extra-bond paternity. These results suggest that size dimorphism is associated with the sort of intrasexual competition described by traditional classifications of social mating system, whereas plumage-colour dimorphism is associated with cryptic female choice. However, when we break up plumage-colour dimorphism according to whether it is due to melanins, carotenoids or structural colours, we find that each category of plumage-colour dimorphism shows a different pattern of covariation. The correlation between overall plumage-colour dimorphism and the rate of extra-bond paternity is due to structural colours, whereas melanin-based dimorphism is associated with sex differences in parental care. The former result is particularly interesting given that new work suggests structural colours are associated with active sexual displays and the reflection of ultraviolet light.

Abstract: Rad23 is an evolutionarily conserved protein that is important for nucleotide excision repair1,2,3. A regulatory role has been proposed for Rad23 because rad23 mutants are sensitive to ultraviolet light but are still capable of incising damaged DNA4,5. Here we show that Rad23 interacts with the 26S proteasome through an amino-terminal ubiquitin-like domain (UbLR23). The carboxy terminus of Rad23 binds to the Rad4 DNA repair protein and creates a link between the DNA repair and proteasome pathways. The ultraviolet sensitivity caused by deletion of the UbLR23 domain may therefore arise from its inability to interact with the proteasome. The fusion proteins glutathione S-transferase (GST)–Rad23 and Rad4–haemagglutinin (HA), and the proteasome subunits Cim3 and Cim5, cofractionate through consecutive chromatography steps. The ubiquitin-like domain of human Rad23 (UbLHRB) also interacts with the human proteasome. These results demonstrate that ubiquitin-like domains (UbLs) represent a new class of proteasome-interacting motifs.

Abstract: We investigate numerically the properties of metallo-dielectric, one-dimensional, photonic band-gap structures. Our theory predicts that interference effects give rise to a new transparent metallic structure that permits the transmission of light over a tunable range of frequencies, for example, the ultraviolet, the visible, or the infrared wavelength range. The structure can be designed to block ultraviolet light, transmit in the visible range, and reflect all other electromagnetic waves of lower frequencies, from infrared to microwaves and beyond. The transparent metallic structure is composed of a stack of alternating layers of a metal and a dielectric material, such that the complex index of refraction alternates between a high and a low value. The structure remains transparent even if the total amount of metal is increased to hundreds of skin depths in net thickness.

Abstract: Chitin, a linear polysaccharide composed of (1→4)-linked 2-acetamido-2-deoxy-β-d-glucopyranose (GlcNAc) residues, and chitosan, the fully or partially N- acetylated, water-soluble derivative of chitin composed of (1→4)-linked GlcNAc and 2-amino-2-deoxy-β-d-glucopyranose (GlcN), have been proposed as elicitors of defense reactions in higher plants. We tested and compared the ability of purified (1→4)-linked oligomers of GlcNAc (tetramer to decamer) and of GlcN (pentamer and heptamer) and partially N- acetylated chitosans with degrees of acetylation (DA) of 1%, 15%, 35%, 49%, and 60% and average degrees of polymerization between 540 and 1100 to elicit phenylalanine ammonia-lyase (PAL) and peroxidase (POD) activities, lignin deposition, and microscopically and macroscopically visible necroses when injected into the intercellular spaces of healthy, nonwounded wheat ( Triticum aestivum L.) leaves. Purified oligomers of (1→4)-linked GlcN were not active as elicitors, whereas purified oligomers of (1→4)-linked GlcNAc with a degree of polymerization ≥ 7 strongly elicited POD activities but not PAL activities. Partially N- acetylated, polymeric chitosans elicited both PAL and POD activities, and maximum elicitation was observed with chitosans of intermediate DAs. All chitosans but not the chitin oligomers induced the deposition of lignin, the appearance of necrotic cells exhibiting yellow autofluorescence under ultraviolet light, and macroscopically visible necroses; those with intermediate DAs were most active. These results suggest that different mechanisms are involved in the elicitation of POD activities by GlcNAc oligomers, and of PAL and POD activities by partially N- acetylated chitosan polymers and that both enzymes have to be activated for lignin biosynthesis and ensuing necrosis to occur.

Abstract: A portable data collection device having a modular imaging-based dataform reader. The dataform reader includes a two dimensional imaging assembly adapted to image and decode a dataform printed using ink that fluoresces when illuminated by ultraviolet light. The imaging assembly includes a two dimensional photosensor array and is actuatable to generate a signal representative of reflected illumination from a target area of the imaging assembly and further includes an illumination assembly having a strobing ultraviolet light source. The illumination assembly includes a pair of flash tube strobe lights which have their output illumination filtered through respective ultraviolet filter thereby permitting only illumination in the ultraviolet range to exit the dataform reader and illuminate the imaging target area. The high intensity, strobing light of the ultraviolet light source permits a reduced exposure period. A targeting illumination assembly is also provided to aid in aiming the device at a target dataform. The targeting illumination assembly and illumination assembly are alternately energized to reduce reflected glare. Fluorescence from the dataform is focused by an optic assembly onto the photosensor array forming an image of the dataform. Image processing circuitry is provided for processing and decoding the image of the dataform.

Abstract: PROBLEM TO BE SOLVED: To obtain an org. electroluminescent element which is suitable as a polysilane-based planar ultraviolet light source stably emitting light at room temp. by using a thin polydimethylsilane film as the luminescent layer. SOLUTION: This element has at least a luminescent layer between a pair of electrodes and the luminescent layer comprisies a thin polysilane film represented by the formula: [(CH3 )2 Si]n . (wherein n is 5 to about 10,000). The luminescent layer is formed by a dry method such as vapor deposition, sputtering, or laser ablation. The thickness of the film is pref. about 500-10,000Å. The luminescent layer may contain a compd. having a hole transpot capability and a compd. having an electron transport capability each in an amt. of up to about 30wt.%.

Abstract: Methods and apparatus for detecting the possible rejection of a transplanted tissue by a host. The transplanted tissue is subjected to illumination with light to induce fluorescence. The light can be ultraviolet light, visible light or infrared light, which can be used alone or in any combination, which means one, two or three forms of light may be used together. The induced fluorescence is collected and analyzed, then compared with fluorescence that is obtained using the same procedure for a known, healthy tissue that is the same type of tissue as the transplanted tissue. Also provided are methods and apparatus related to the determination of probe orientation and the need for biopsy.

Abstract: This paper reports on the fabrication and characterization of hybrid organic-inorganic glass sol-gel slab and channel waveguides by ultraviolet light imprinting in thin films deposited by a one-step dip-coating process. The adjustment of chemical composition of the materials provides precise selection of refractive index from 1.48 to 1.52 at the wavelength of 632.8 mn. The refractive index of the waveguides at 1.55 /spl mu/m is similar to that of optical fiber, thus reducing the reflection loss between the two to less than 0.01 dB. The effect of ultraviolet light exposure and heat treatment on waveguide refractive index is studied. Fabrication parameters to produce ridge waveguides are optimized to achieve very smooth side walls. Propagation losses in these waveguides are /spl sim/0.1 dB/cm. Single mode buried waveguides, at 1.55 /spl mu/m wavelength, with circular mode profile are demonstrated.

Abstract: The nature of the selective pressures which have resulted in the conical-papillate shape of the cells of the adaxial epidermis of many petals has been a matter for considerable speculation. One suggestion is that this shape focuses light within epidermal cells resulting in an increase in the amount of light absorbed by the floral pigments, intensifying the colour of the petals and possibly enhancing their attractiveness to potential pollinators; another is that conical cells aid pollinator orientation on the flower, either visually or when touched. The recent identification of a mutation at the MIXTA locus of Antirrhinum majus (which blocks the formation of conical petal cells) has allowed us to test this hypothesis. We report the results of field experiments indicating that, where pollinator number limits seed-set, flowers with conical epidermal cells receive more pollinator attention than do those with flat cells. Through the use of double mutants we have examined whether preferences for flowers with conical cells operate through the perception of flavonoid pigments. We have also examined the appearance of flowers with and without conical cells under ultraviolet light to determine whether differences in absorption or reflectance of light at these wavelengths may influence pollinator preference.

Abstract: Vegetational history can help us to predict future environments by providing data for testing AGCMs, for indicating the vegetational response to rapid warming and changing CO2 concentrations, and for mathematical modelling of vegetation. Most of the data are palynological, and there are well over 100 pollen diagrams from tropical regions. Maps are presented showing summarized pollen diagrams from the lowlands of South-East Asia and the West Pacific, Tropical Latin America and Tropical Africa. In all these regions there is some evidence suggesting that at the LGM lowland forests were somewhat restricted in area and included montane elements. This is consistent with cooler and drier climate at the LGM. From the montane and lowland areas of these three regions, the pollen evidence is summarized in altitudinal diagrams. These suggest considerable depression of altitudinal zones at the LGM, suggesting temperatures c. 5–10°C cooler than now. These results conflict with earlier oxygen isotope data from marine foraminifera, but do not conflict with more recent oxygen isotope measurements from tropical corals. It is also suggested that altitudinal movements may be partly controlled by CO2 concentration and ultraviolet light.

Abstract: Colonies of the harvester ant, Pogonomyrmex barbatus, perform a variety of tasks. The behavior of an individual worker appears to depend on its recent history of brief contacts with ants of the same and other task groups. The purpose of this study was to determine whether task groups differ in cuticular hydrocarbon composition. We compared the cuticular hydrocarbon composition of ants collected under natural conditions as they performed one of three tasks: patrolling (locating food sources), foraging, or nest maintenance. Task groups differed significantly in the relative proportions of classes of hydrocarbon compounds, as well as in individual compounds. Relative to nest maintenance workers, foragers and patrollers had a higher proportion of straight-chain alkanes relative to monomethylalkanes, dimethylalkanes, and alkenes. There was no significant difference in the chain length of n-alkanes among the task groups. Foragers did not differ in hydrocarbon composition from patrollers. Colonies differed significantly from one another in hydrocarbon composition, but task groups differed in consistent ways from colony to colony, suggesting that the mechanism responsible for task-related hydrocarbon composition was the same in all colonies. P. barbatus workers switch tasks during their lifetimes, suggesting that cuticular hydrocarbon composition changes during adulthood as well. Nest maintenance workers are probably younger than foragers and patrollers and perform very little of their work outside of the nest. Task-related hydrocarbon differences detected here may be associated with worker age, and/or the abiotic characteristics (temperature, humidity, and ultraviolet light) of the interior and exterior work environments.

Abstract: The mechanisms and antioxidant activities of six natural phenolics against lipid oxidation induced by ultraviolet (UV) radiation or Fe 2+ were studied. An oil emulsion was pre- pared with flax oil and the thiobarbituric acid-reactive sub- stances (TBARS) method was used to determine lipid oxidation. The antioxidant activities of the six phenolics against UV-in- duced lipid oxidation were as follows: quercetin > rutin = caf- feic acid = ferulic acid = sesamol > catechin. The inhibitory concentrations (IC 50 ) showed that the effectiveness of these an- tioxidants against Fe 2+ -induced lipid oxidation was in the order quercetin (1.7 µM) > rutin (10.3 µM) > catechin (14.9 µM) > sesamol (18.5 µM) > caffeic acid (19 µM) > ferulic acid (>250 µM), and quercetin was more efficient than butylated hydroxy- toluene (BHT) (2.9 µM). Quercetin and rutin had absorption maxima at the UV-A (320-380 nm) region, while the other phe- nolics tested had absorption maxima near (catechin, 278 nm) or at the UV-B (280-320 nm) region. The stoichiometric ratios of quercetin, rutin, catechin, and caffeic acid to Fe 2+ were 3:1, 2:1, 1:1, and 1:1, respectively. Although free-radical scaveng- ing capability of antioxidants was the most critical, UV absorp- tion and/or Fe 2+ -chelation properties of natural phenolics also contributed significantly to the control of lipid oxidation in- duced by UV or Fe 2+ in oil systems. JAOCS 75, 1717-1721 (1998).

Abstract: Publisher Summary This chapter discusses fluorescence photoactivation as an alternative technology for probing cytoskeleton dynamics. In this approach, the protein is tagged with a caged fluorochrome. This probe molecule is nonfluorescent until illuminated with a brief pulse of ultraviolet light. Such illumination leads to photolysis of the caging groups and generation of a fluorescent species. In principle, fluorescence photoactivation can avoid the problem of generation of local oxidative damage inherent to photobleaching and can also produce a more favorable signal-to-noise ratio for imaging. Photoactivation can also produce toxic by-products in the form of the nitrosoaldehyde or nitrosoketone side products from photolysis. The chapter discusses the progress in caged fluorescent probes. The first caged fluorescent probe that was used for a biological experiment was a fluorescein derivative, C2CF-sulfo-N-hydroxysuccinimide. This probe, attached to tubulin, led to the discovery of poleward flux in mitotic spindles. C2CF is highly hydrophobic, and most proteins other than tubulin tend to aggregate if they are labeled with it.

Abstract: Recently a suite of relatively specific hindlimb deformities have been observed in several anuran species in North America. These deformities include ectopic and supernumerary limbs and missing limbs, limb segments, or digits. The objective of this study was to assess two stressors hypothesized as responsible for limb malformations in amphibians: methoprene, an insect growth regulator that, through interaction with the retinoic acid signaling system, could possibly cause limb deformities, and ultraviolet (UV) light. Northern leopard frogs (Rana pipiens) were exposed to several different concentrations of methoprene both in the absence and presence of UV light designed to mimic the UV wavelength spectrum present in sunlight. Exposures were initiated at early embryonic stages (newly fertilized eggs) and continued through emergence of the forelimbs of the frogs. At the highest methoprene concentration tested, both in the absence and presence of UV light, severe developmental effects were observed, with all organisms dying within 12 to 16 d of test initiation. However, exposure to the pesticide did not cause limb malformations. Irrespective of methoprene treatment, a very high percentage (∼50%) of animals held under the UV light for 24 d developed hindlimb malformations. These malformations usually were bilateral and sometimes completely symmetrical, and consisted of missing limb segments and missing or reduced digits. A complete proximal to distal representation of the deficiencies occurred, ranging from missing or malformed femurs to the absence of single digits or digit segments. The developmental period of greatest sensitivity to UV light occurred during very early limb bud development, corresponding with formation of the apical ectodermal ridge. The significance of these findings in terms of deformed frogs in the field is uncertain. Although the deformity types observed (i.e., missing limb segments and digits) were similar to those seen in some field specimens, the UV light treatment did not cause the full range of malformations observed in animals from the field (e.g., supernumerary limbs, nonbilateral deformities). Furthermore, although the artificial light spectrum utilized mimicked the relative UV spectrum present in sunlight, it did not match full sunlight intensity, and did not accurately mimic visible wavelengths. Finally, the relationship of the UV light dose used in the laboratory to that actually experienced by amphibians in the field is uncertain. Despite these questions, our findings suggest that UV light should be further considered as a plausible factor contributing to amphibian malformations in field settings.

Abstract: Cure-on-demand, moisture-curable compositions of one or more compounds comprising molecules having reactive silane functional groups and an acid generating material are taught herein. The acid generating material releases an acid upon exposure to heat, ultraviolet light, visible light, electron beam irradiation or microwave irradiation to initiate and accelerate the cross-linking reaction. Articles prepared using the moisture curable materials are also disclosed, as are methods of curing those materials.

Abstract: The triboluminescence intensity from stress-activated Sr3Al2O6:Eu,Dy (SAO-ED) was so strong that we could see it with the naked eye in the atmosphere The luminescence integrated intensity was about five hundred times as high as that of crystal sugar We think that the light emission is due to the movement of dislocations and the 4f7–4f65d transition in the doped Eu2+ ions from the analysis of the emitted light Furthermore, we have discovered the new phenomenon that the luminescence intensity of the SAO-ED is recovered by the irradiation of ultraviolet light