Image resolution limit optimization for quantum imaging with undetected light

SummaryThe effects of sub-optimal day/night temperatures (15°/10°C; PPFD 250 ?mol m-2 s-1), or low light intensity (25°/18°C; PPFD 100 ?mol m-2 s-1), or sub-optimal temperatures combined with low light intensity (15°/10°C; PPFD 100 ?mol m-2 s-1) on hypocotyl and leaf growth were studied in watermelon (Citrullus lanatus) seedlings. We also measured the activities of anti-oxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as tissue concentrations of malondialdehyde (MDA), proline, and soluble sugars under the three experimental conditions and in an optimal-conditions control group. Our observations indicated that hypocotyl elongation and leaf area expansion were inhibited by sub-optimal temperatures. Stem diameter growth was inhibited by low light intensity, whereas low light had a positive effect on hypocotyl elongation and leaf area growth. However, the growth of hypocotyls and leaves were significantly inhibited by the combination of sub-optimal temperatures and low light intensity. After exposure to sub-optimal temperatures alone, or in combination with a low light intensity, SOD activity increased by 61.9% and 39.5%, and POD activity increased by 185.1% and 120.7%, respectively. However, CAT activity declined by 22.0% under sub-optimal temperatures conditions. Moreover, the low light intensity increased CAT activity by 38.1%, but had weak effect on both SOD and POD activities. The activities of SOD and POD probably increased as a result of the activation of the cellular anti-oxidant defence system. CAT activity appeared to be more strongly affected by sub-optimal temperatures or low light intensity compared with the combined effect of low temperatures and low light. Sub-optimal temperatures increased MDA concentrations and caused lipid peroxidation in cell membranes. However, low light could alleviate the damage due to lipid peroxidation under suboptimal temperatures. Proline and soluble sugar concentrations increased significantly when exposed to sub-optimal temperatures alone or in combination with low light intensity. The accumulation of proline and soluble sugars demonstrated the positive effects of both stresses on osmotic adjustment and metabolic regulation. These findings indicated that watermelon seedlings differed in their growth and physiological responses to sub-optimal temperatures and/or low light intensity, and that sub-optimal temperatures can activate the anti-oxidant system in leaves, the latter being related to the increase in ROS scavenging enzyme activities. However, a low light intensity could alleviate the oxidative damage caused to leaves under sub-optimal temperatures.

Leaf mesostructure, photochemical activity, and chloroplast photophosphorylation (PP) in the fourth true leaf of 28-day-old Chinese cabbage (Brassica chinensis L.) plants were investigated. Plants were grown under a light source based on red (650 nm) and blue (470 nm) light-emitting diodes (LED) with red/blue photon flux ratio of 7: 1 and under illumination with high-pressure sodium lamp (HPSL) at photon flux densities of 391 ± 24 μmol/(m2 s) (“normal irradiance”) and 107 ± 9 μmol/(m2 s) (“low irradiance”) in photosynthetically active range. At normal irradiance, the leaf area in plants grown under HPSL was twofold higher than in LED-illuminated plants; other parameters of leaf mesostructure were little affected by spectral quality of incident light. The lowering of growth irradiance reduced the majority of leaf mesostructure parameters in plants grown under illumination with HPSL, whereas in LED-illuminated plants the lowered irradiance reduced only specific leaf weight but increased the leaf thickness and dimensions of mesophyll cells and chloroplasts. The photochemical activity of isolated chloroplasts was almost independent of growth irradiance and light spectral quality. Light quality and intensity used for plant growing had a considerable impact on PP in chloroplasts. At normal light intensity, the highest activity of noncyclic PP in chloroplasts was observed for plants grown under HPSL; at low light intensity the highest rates of PP were noted for plants grown under LED. The P/2e− ratio, which characterizes the degree of PP coupling to electron transport in the chloroplast electron transport chain, showed a similar pattern. Thus, the narrow-band spectrum of the light source had little influence on leaf mesostructure and electron transport rates. However, this spectrum significantly affected the chloroplast PP activity. The PP patterns at low and normal light intensities were opposite for plants grown under LED and HPSL light sources. We suppose that growing plants under LED array at normal light intensity disturbed the chloroplast coupling system, thus preventing the effective use of light energy for ATP synthesis. At low light intensity, chloroplast PP activity was significantly higher under LED illumination, but plant growth was suppressed because of impaired adaptation to low light intensity.

Far-red light mediates light energy capture and distribution in soybeans (Glycine max L.) under the shade

Effect of ambient light intensity on growth performance and diurnal stress response of juvenile starry flounder (Platichthys stellatus) in recirculating aquaculture systems (RAS)

Cyclic electron transport around photosystem I (PS I) was discovered more than a half-century ago and two pathways have been identified in angiosperms. Although substantial progress has been made in understanding the structure of the chloroplast NADH dehydrogenase-like (NDH) complex, which mediates one route of the cyclic electron transport pathways, its physiological function is not well understood. Most studies focused on the role of the NDH-dependent PS I cyclic electron transport in alleviation of oxidative damage in strong light. In contrast, here it is shown that impairment of NDH-dependent cyclic electron flow in rice specifically causes a reduction in the electron transport rate through PS I (ETR I) at low light intensity with a concomitant reduction in CO2 assimilation rate, plant biomass and importantly, grain production. There was no effect on PS II function at low or high light intensity. We propose a significant physiological function for the chloroplast NDH at low light intensities commonly experienced during the reproductive and ripening stages of rice cultivation that have adverse effects crop yield.

Crop growth and nitrogen turnover under increased temperatures and low autumn and winter light intensity

The effect of temperature and light intensity on the polar lipidome of endophytic brown algae Streblonema corymbiferum and Streblonema sp. in vitro was investigated. More than 460 molecular species have been identified in four glycoglycerolipids classes, five phosphoglycerolipids classes and one betaine lipid class. The lipids glucuronosyldiacylglycerol and diacylglyceryl-N,N,N-trimethyl-homoserine were found in the algae of the order Ectocarpales for the first time. A decrease in cultivation temperature led to an increase in the unsaturation level in all classes of polar lipids. Thus, at low temperatures, the content of 18:4/18:4 monogalactosyldiacylglycerol (MGDG), 20:5/18:4 digalactosyldiacylglycerol (DGDG), 18:3/16:0 sulfoquinovosyldiacylglycerol (SQDG), 18:3/18:3 and 18:3/18:4 phosphatidylglycerol (PG), 20:4/20:5 and 20:5/20:5 phosphatidylethanolamine (PE), 14:0/20:5, 16:0/20:5 and 20:5/20:5 phosphatidylcholine (PC), 20:5/20:4 phosphatidylhydroxyethylglycine and 18:1/18:2 DGTS increased. At high temperatures, an increase in the content of chloroplast-derived MGDG, DGDG and PG was observed. Both low and high light intensities caused an increase in 20:5/18:3 MGDG and 18:3/16:1 PG. At low light intensity, the content of DGDG with fatty acid (FA) 18:3 increased, and at high light intensity, it was with FA 20:5. The molecular species composition of extraplastid lipids also showed a dependence on light intensity. Thus, the content of PC and PE species with C20-polyunsaturated FA at both sn-positions, 18:1/18:1 DGTS and 16:0/18:1 phosphatidylinositol increased. Low light intensity induced a significant increase in the content of chloroplast-derived 18:1/16:1 phosphatidylethanolamine.

Nonablative skin rejuvenation using laser, intense pulsed lights (IPLs), or radiofrequency techniques are becoming increasingly popular. In this paper, a novel protocol that integrates IPL sessions, low intense light and vitamin C, low-weight hyaluronic acid, betaglucan dermal injection versus IPL photorejuvenation as monotherapy is compared. A group of 100 patients, all women, with ages ranging from 35 to 65 years old (median age 56.3) with different degrees of photodamage was considered. A blinded control study was done. The patients were divided not randomly into two groups. These groups are similar for ages, skin types, and degrees of photoaging distribution. A first group of 40 patients had monotherapy consisting of seven sessions of IPL only. A second group of 60 patients had triple therapy consisting of seven sessions of IPL as well as nine sessions of low intense diode light and also biostimulation by drugs. Considering only the improvement in hyperpigmentations and teleangectasias, the monotherapy and the triple therapy show good results with no significant statistical difference between the two groups. Considering the improvement in skin texture and firmness in the group treated only with monotherapy, 30% (12 patients) had positive results, and 70% (28 patients) had poor results. In the group treated with triple therapy, 70% (42 patients) had positive results, and 30% (18 patients) had poor results, with the main differences in skin silicone negative imprints. On the basis of the data presented, the new technique of IPL, low intensity diode light, and multidrugs biostimulation seems to be a safe and effective method for skin rejuvenation and upgrades the effects of IPL in the fibroblasts' stimulation.

Solar cell performances at low light intensity are practically more important for power generation capacity in the entire life cycle. Previous studies have revealed that efficiency and maximum power of the solar cells with low shunt resistance become lower at the low light intensity. In contrast, our study has demonstrated the effects of paste or glass frit as paste constituents on shunts and recombination, as well as open-circuit voltage of solar cells with floating contact method. However, the effects of the glass frit in the paste on the low light performances of the cells have not been actually clear yet. For this reason, in this study, the effects of the glass frit itself on the low light performances of the cells are investigated. This is because even though the glass frit is an indispensable constituent for silver paste to electrically contact to the solar cells, the effects of the glass frit itself on cell performance have not been clear yet. In conclusion, the glass frit itself makes the solar cell performances lower at the low light intensity, especially open-circuit voltage and fill factor, by causing shunts and recombination, which means that the effects of paste constituents on shunts and recombination are important not only for solar cell performances at 1 sun, but also for the performances at low light intensity.

In-depth investigation on the photostability and charge separation mechanism of Ag3PO4/g-C3N4 photocatalyst towards very low visible light intensity

Transformed tobacco plants expressing a rice cysteine proteinase inhibitor (OC‐I) and non‐transformed plants were grown in a controlled environment and subjected to various stresses. Two‐month‐old transformed and non‐transformed plants were exposed for 5 days to drought conditions by withholding watering. High temperature (40 °C) was applied additionally at day 6th for 5 h either individually or in combination with drought. All stress treatments were applied under low (150 μmol m−2 s−1 PPFD) and high light intensity (HL) of 1000 μmol m−2 s−1 PPFD to determine if OC‐I expression might provide protection under combination of stresses usually existing in nature. Drought stress led to diminution in leaf relative water content, photosynthesis inhibition, decrease in chlorophyll content and accumulation of malondialdehyde and proline. Heat stress alone did not affect the plants significantly, but intensified the effect of drought stress. HL intensity further increased the proline content. OC‐I transformed plants grown under low light intensity had significantly higher total superoxide dismutase and guaiacol peroxidase activities as well as their isoforms than non‐transformed control plants under non‐stress and stress conditions. Catalase activity was not highly affected by OC‐I expression. Results indicate that OC‐I expression in tobacco plants provides protection of the antioxidative enzymes superoxide dismutase and guaiacol peroxidise under both non‐stress and stress conditions.

One of the pleasures of teaching introductory biology courses is learning new things about old, familiar subjects … such as the differences between eukaryotes and prokaryotes. For a eukaryotic cell biologist, such learning usually entails examining how bacteria function, in ways other than how they replicate and transcribe DNA and how they synthesize protein. I find it interesting, for example, to understand how bacteria maintain their distinctive spherical, rod-like or spiral shapes; or how they make an external cell wall, if they have one; or how they segregate the products of DNA replication faithfully into daughter cells. New answers to these questions are especially interesting because, in my mistaken eukaryote-centric view, bacteria lack cytoskeletons and cytoskeletal proteins, which might be involved in maintaining cell shape, regulating cell wall synthesis, and erecting something like a mitotic apparatus. Which brings me to a second and equally delightful pleasure derived from teaching introductory biology: debunking worn-out notions. Bacteria do possess cytoskeletons made of proteins which resemble the actin and tubulin familiar to eukaryotic cell biologists. Here I review several, recently published videos that characterize the in vitro behaviors of the actin-like protein, ParM (also known as StbA), and the tubulin-like protein, FtsZ and its in situ localization during cell division. For sake of completeness, I also briefly mention some recent work on the protein crescentin (CreS), an intermediate filament-like molecule, in the absence of published videos. By way of background material, readers may find the recent review by Michie and Lowe (2006) on the dynamics of bacterial cytoskeletal proteins helpful, including the authors' provocative list of “Future Issues to be Resolved.” Also, students and their teachers may wish to compare the videos reviewed below with those involving tubulin and actin (Watters, 2002 , 2004 , 2005 ), which could generate some interesting discussions about the differences and similarities of prokaryotes and eukaryotes. In such discussions, for example, students may raise questions concerning the evolution of “the cytoskeleton”; in which case, they may also find an earlier review on the subject (van den Ent et al., 2001 ) and commentary (Erickson, 2001 ) very helpful, for both an overview and a relevant bibliography. Students and their teachers will also want to discuss critically whether the similarities exhibited by the bacterial and eukaryotic cytoskeletal proteins reflect phylogenetic homologies or, rather, represent good examples of convergent evolution. At this point, readers more familiar with eukaryotic cell biology should be advised the videos being reviewed (as well as the review figures below) were, with one exception, obtained using 100× objectives: that is, at the limits of light microscopy resolution. Thus, the fields of view are small and the images do not seem as large or as sharp as seen in lower-magnification images of eukaryotic cells. Moreover, all but one of the video images were obtained by fluorescence microscopy at low light intensities, which required longer time exposures and time-lapse digital imaging (with accompanying loss of intervening visual detail). In contrast, the set of images portraying FtsZ behavior in vitro was obtained using an atomic force microscope (AFM), which is not a microscope in the usual sense of the term. An AFM lacks lenses and forms an image by means of a probe that traverses the object in a systematic manner, one line at a time. The image formed by the kind of AFM most commonly used for molecular studies is topographical in nature, and image details receive contrast from their size (changes in the z-axis). These images are created in a raster-like manner by the movement of a very fine, whisker-like projection across the surface of an object. AFM resolution, consequently, reflects the size of the probe tip, relative to the detail being probed, and not the diffraction of electromagnetic or electron radiation as seen in more familiar micrographs. With a very small tip, spatial resolution in an AFM image can be very high. Temporal resolution, however, is limited, because of the time usually required to achieve raster-like movements across the field. More information about AFM may be obtained at http://stm2.nrl.navy.mil/how-afm/how-afm.html#General%20concept.

Relating to magnified image formation systems, we consider two processes in this work: quantum and classical incoherent imaging. There are similarities and differences between them. A similarity is that the optical transfer functions (OTFs) of both systems are obtained by calculating a correlation function. Concerning the differences, only two were found. The first difference is that, unlike classical incoherent imaging, quantum imaging with photon pairs generated by spontaneous parametric down-conversion is sensitive to the phase in the function which describes the object. The second difference is that the OTF of the quantum imaging system is a cross-correlation function of the OTFs of the signal and idler arms, while the OTF of the classical incoherent imaging system is an autocorrelation of the only pupil function existing in this case. We explore experimentally the second difference. We report the observation of a highly resolved image produced by a quantum light source in a setup where an incoherent light source is unable to spatially resolve the image of the object. The spatial resolution of the image is studied in a situation where the size of the object is magnified at the image.

In order to evaluate the effect of light intensity and photoperiod on heading and to establish the reaction types of barley, a set of barley germplasm of various geographical origin and growth habit was examined in a series of controlled growth chamber experiments combining two levels of light intensity with long and short photoperiod regimes. Low light intensity contributed only a limited portion to the total variance of heading and this originated to a large extent from the genotype × light intensity interaction for both photoperiods. Under the long photoperiod regime the effect of low light intensity was only apparent in a significant delay in heading. Under a short photoperiod the type of sensitivity depended on the growth habit. Low light intensity hastened plant development in 15% of the spring barley varieties, while the flowering of 44% of the winter barley varieties was significantly delayed. Establishing the reaction types for photoperiod and low light intensity in this range of barley germplasm made it possible to identify the typical reaction types of the two growth-habit groups. In addition, it also became possible to identify genotypes with contrasting or unusual combinations of these traits.

The amount of demand for banana commodities has increased in line with the increase of population as well as mineral and nutritional needs. However, banana production capacity is still low. Generally, banana plants grow well in areas with high light intensity. Banana cultivation as interplant facing problems, such as low light intensity, which affects the growth and production of banana plants. One effort to increase banana production is through the development of banana cultivation that is tolerant of low light intensity. This study aims to compare the character of vegetative and fruit of dwarf cavendish banana originating from two different regions, namely the mainland and the island regions of Southeast Sulawesi, to get the most resistant to low light intensity. The result showed that there is no significant difference between the two. This study provides guidance for further studies on the development of banana cultivation in determining the type of banana that is most suitable for planting on low light intensity.