Narrow Red Band Research Articles

Taxonomic revision of Montina (Hemiptera: Heteroptera: Reduviidae) from Colombia with description of three new species

The Neotropical assassin bug genus Montina Amyot & Serville, 1843 (Reduviidae: Harpactorinae) is revised for Colombia. Montina has not been adequately explored taxonomically, with its last described species published in 1867. It has ten valid species distributed in tropical areas of Central and South America, but none of them have been formally recorded from Colombia. We describe three new species, M. calarca Mejía-Soto & Forero sp. nov., M. gladiator Mejía-Soto & Forero sp. nov., M. tikuna Mejía-Soto & Forero sp. nov., and report seven species as new records for the country: M. confusa (Stål, 1859), M. distincta (Stål, 1859), M. fumosa (Stål, 1867), M. lobata Stål, 1859, M. ruficornis (Fabricius, 1803), M. scutellaris Stål, 1859, and M. testacea (Stål, 1859). Montina calarca sp. nov. is distinguished by the reddish coloration with black head and legs; densely setose pronotum; connexival margin rounded on segments 4, 5, and 6 without protuberances, connexivum black with a narrow red band on margin; and translucent yellow membrane with hyaline cells and darkened veins. Montina gladiator sp. nov. is distinguished by the red coloration, with black legs, scutellum, and abdomen; connexival margin 4–5 lobed, 6 straight, segments 2–4 with acute posterior process on each segment, connexivum dark brown to black with a narrow red band on its margin. Montina tikuna sp. nov. is distinguished by the reddish-brown coloration, with black scutellum and abdomen; connexival margin nearly straight, segments 2–4 with small posterior acute process, 5–6 with obtuse process, connexivum black; ventral laterotergites only with black scattered erect setae. New characters help delimit Montina and differentiate it from Ploeogaster Amyot & Serville, 1843, its most similar genus. For all species we provide a diagnosis, images, documentation of genitalia, and distribution maps. A key to all the species of Montina is provided.

Structure Analysis, Photoluminescence, and Non-linear/Linear Optical Parameters of Li-=SUB=-2-=/SUB=-Ge-=SUB=-4-=/SUB=-O-=SUB=-9-=/SUB=- : Mn-=SUP=-4+-=/SUP=- Transparent Glass-Ceramic

In this study, Li2Ge4O9 : Mn4+ transparent glass-ceramic was prepared by conventional melt-quenching. The thermal treatment was used for the devitrification of the sample. The creation of a Li2Ge4O9 nanocrystalline precipitated through the glass matrix was verified by X-ray diffraction and HR-TEM. Electron paramagnetic resonance spectra were employed to confirm the oxidation of Mn2+ to Mn4+ in glass-ceramic after thermal treatment. The photoluminescence spectra displayed a narrow red band centered at 668 nm ascribed to the spin-forbidden 4Eg->4A2g transition of Mn4+. To estimate the optical parameters, UV-Vis-IR absorption spectroscopies were measured. The red shift of the direct optical band gap Eoptg, from 3.81 to 2.55 eV, was observed by increasing the Mn4+ concentration. The dispersion parameters, refraction indices (n, nбесконечность), and oscillator wavelength (λ0) were examined by using Wemple--DiDomenico single-oscillator model. The relationship between the refractive index and the energy gap has been investigated using various models such as Moss, Herve--Vandamme, Ravindra, and Singh--Kumar. In addition, the linear and non-linear optical properties of Li2Ge4O9 : Mn4+ were mentioned. The temperature-dependent luminescence intensity measurement was also carried out. The method of preparation exposed herein for the synthesis of Mn4+-doped GCs might be prevailing to produce identical luminescent ceramics in accordance with the glass's devitrification. Keywords: glass-ceramics, photoluminescence, optical properties, non-linear/linear optical, dispersion parameters, energy gap

Can the narrow red bands of dragonflies be used to perceive wing interference patterns?

Despite numerous studies of selection on position and number of spectral vision bands, explanations to the function of narrow spectral bands are lacking. We investigate dragonflies (Odonata), which have the narrowest spectral bands reported, in order to investigate what features these narrow spectral bands may be used to perceive. We address whether it is likely that narrow red bands can be used to identify conspecifics by the optical signature from wing interference patterns (WIPs). We investigate the optical signatures of Odonata wings using hyperspectral imaging, laser profiling, ellipsometry, polarimetric modulation spectroscopy, and laser radar experiments. Based on results, we estimate the prospects for Odonata perception of WIPs to identify conspecifics in the spectral, spatial, intensity, polarization, angular, and temporal domains. We find six lines of evidence consistent with an ability to perceive WIPs. First, the wing membrane thickness of the studied Odonata is 2.3 μm, coinciding with the maximal thickness perceivable by the reported bandwidth. Second, flat wings imply that WIPs persist from whole wings, which can be seen at a distance. Third, WIPs constitute a major brightness in the visual environment only second after the solar disk. Fourth, WIPs exhibit high degree of polarization and polarization vision coincides with frontal narrow red bands in Odonata. Fifth, the angular light incidence on the Odonata composite eye provides all prerequisites for direct assessment of the refractive index which is associated with age. Sixth, WIPs from conspecifics in flight make a significant contribution even to the fundamental wingbeat frequency within the flicker fusion bandwidth of Odonata vision. We conclude that it is likely that WIPs can be perceived by the narrow red bands found in some Odonata species and propose future behavioral and electrophysiological tests of this hypothesis.

Tracking seasonal drought effects on ecosystem light use efficiency with satellite-based PRI in a Mediterranean forest

Gross primary productivity (GPP) changes occur at different time-scales and due to various mechanisms such as variations in leaf area, chlorophyll content, rubisco activity, and stomatal conductance. Diagnostic estimates of primary productivity are obviously error prone when these changes are not accounted for. Additional complications arise when factors inuencing a biome-specific maximum light use efficiency (LUE) must be estimated over a large area. In these cases a direct estimation of ecosystem LUE could reduce uncertainty of GPP estimates. Here, we analyse whether a MODIS-based photochemical reectance index (PRI) is a useful proxy for the light use efficiency of a Mediterranean Quercus ilex forest. As the originally proposed reference band for PRI is not available on MODIS, we tested the reference bands 1 (620–670 nm), 4 (545–565 nm), 12 (546–556 nm), 13 (662–672 nm), and 14 (673–683 nm) using different atmospheric correction algorithms. We repeated the analysis with different temporal resolutions of LUE (half-hourly to daily). The strongest correlation between LUE and PRI was found when considering only a narrow range of viewing angles at a time (especially 0–10° and 30–40°). We found that the MODIS-based PRI was able to track ecosystem LUE even during severe summer time water limitation. For this Mediterranean-type ecosystem we could show that a GPP estimation based on PRI is a huge improvement compared to the MODIS GPP algorithm. In this study, MODIS spectral band 1 turned out to be the most suitable reference band for PRI, followed by the narrow red bands 13 and 14. As to date no universally applicable reference band was identified in MODIS-based PRI studies, we advocate thorough testing for the optimal band combination in future studies.

Automated detection and mapping of crown discolouration caused by jack pine budworm with 2.5 m resolution multispectral imagery

Jack pine budworm (Choristoneura pinus pinus (Free.)) is a native insect defoliator of mainly jack pine (Pinus banksiana Lamb.) in North America east of the Rocky Mountains. Periodic outbreaks of this insect, which generally last two to three years, can cause growth loss and mortality and have an important impact ecologically and economically in terms of timber production and harvest. The jack pine budworm prefers to feed on current year needles. Their characteristic feeding habits cause discolouration or reddening of the canopy. This red colouration is used to map the distribution and intensity of defoliation that has taken place that year (current defoliation). An accurate and consistent map of the distribution and intensity of budworm defoliation (as represented by the red discolouration) at the stand and within stand level is desirable.Automated classification of multispectral imagery, such as is available from airborne and new high resolution satellite systems, was explored as a viable tool for objectively classifying current discolouration. Airborne multispectral imagery was acquired at a 2.5m resolution with the Multispectral Electro-optical Imaging Sensor (MEIS). It recorded imagery in six nadir looking spectral bands specifically designed to detect discolouration caused by budworm and a near-infrared band viewing forward at 35° was also used. A 2200nm middle infrared image was acquired with a Daedalus scanner. Training and test areas of different levels of discolouration were created based on field observations and a maximum likelihood supervized classification was used to estimate four classes of discolouration (nil-trace, light, moderate and severe). Good discrimination was achieved with an overall accuracy of 84% for the four discolouration levels. The moderate discolouration class was the poorest at 73%, because of confusion with both the severe and light classes. Accuracy on a stand basis was also good, and regional and within stand discolouration patterns were portrayed well. Only three or four well-placed spectral bands were needed for a good classification. A narrow red band, a near-infrared and short wave infrared band were most useful. A forward looking band did not improve discolouration estimation, but further testing is needed to confirm this result.This method of detecting and classifying discolouration appears to provide a mapping capability useful for conducting jack pine budworm discolouration surveys and integrating this information into decision support systems, forest inventory, growth and yield predictions and the forest management decision-making process.

The normalized difference vegetation index of small Douglas-fir canopies with varying chlorophyll concentrations

The normalized difference vegetation index (NDVI), calculated from reflected red and near-infrared radiation, has been related to various vegetation properties, including leaf area index, light absorption capacity, and photosynthetic potential. In an experiment with miniature canopies of 1-m-tall Douglas-fir ( Pseudotsuga menziesii) seedlings, we modified leaf area index, light absorption capacity, and photosynthetic potential by altering the concentration of chlorophyll in foliage and by controlling the density of seedlings. We measured canopy photosynthesis and light transmission in controlled-environment chambers and then transferred seedlings to a hemispheric illumination system where we measured canopy reflectance. We found that altering the visible band used for computation of a normalized vegetation index substantially changed the correlations between the index and canopy properties. For example, the normalized index was best correlated to light absorption capacity when we used a narrow red band (671–674 nm; R 2 = 0.71), and least correlated when we used a narrow green band (565–575 nm; R 2 = 0.27). On the other hand, the index computed with the 565–575 nm band was best correlated with the photosynthetic potential of canopies grown in sunlight (R 2 = 0.84), and the correlation was lower when a narrow red band was used (R 2 = 0.37). The cause of these differences is chlorophyll. The green regions of reflectance spectra were much more sensitive to changes in chlorophyll concentration compared with the red or near-infrared regions. Increased chlorophyll concentration was also related to increased photosynthetic potential when canopies had been grown under full sunlight. However, we found no statistically significant relationship between leaf chlorophyll concentration and canopy light absorption.

The luminescent probes europium and terbium-DTPA localize in cells and organs and serve as analogues for gadolinium-DTPA

The Europium (III) and Terbium (III) complexes of diethylene-triaminepenta-acetate (DTPA) were prepared to be luminescent, histochemical analogues for the recently developed specific paramagnetic resonance contrast agents such as Gadolinium (III)DTPA. Electron probe microanalysis (energy dispersive X-ray spectroscopy) demonstrates that the Eu and Gd-DTPA colocalize in various tissues. Eu, Tb and Gd are closely related as seen in the Periodic Table (Fig. 1). The structures of Eu and Gd-DTPA (Fig. 2) as well as Tb-DTPA are very similar. Fig 3 shows the synthetic path of one of these compounds, Na2Eu (DTPA)H2O. Fig. 4 depicts a Europium(III) complex fluorescence-excitation scheme, where UV (360 - 440 nm) excites electron energy to the 5D7 state, followed by a rapid (less than 5 μec) non-radioactive relaxation to the luminescent D0 state. There is a slow return to the ground 7F manifold with emission from 575-790 nm. Crystals of the Europium complex exhibit intense, non-fading fluorescence (Fig. 5) in a narrow red band when observed with a UV excitation filter (360-440 nm), a midrange chromatic beam splitter (460 nm), and a long pass barrier filter (590 nm). The same crystal is seen in Differential Interference Contrast (DIC) light microscopy (LM) (Fig. 6).