Bright Band Research Articles

Effect of low-level flow and Andes mountain on the tropical and mid-latitude precipitating cloud systems: GPM observations

The effect of different directional South American low-level flow (SA-LLF) and topography on the near surface rainfall characteristics are validated in the present study. The near surface precipitation characteristics of the precipitating cloud systems (PCSs) are investigated under the influence of low-level flow (LLF) at 850 hPa and topography. Global precipitation measurement dual precipitation radar (GPM-DPR) data is used to define the PCSs. The PCSs consist of valuable information, including radar reflectivity (Ze), rain rate (RR), storm top height (STH), and DSD (drop size (Dm) and drop concentration (Nw) parameters). For LLF, we considered wind data at 850 hPa and for each PCS, the average wind angle is calculated using U and V component of wind component from European Center for Medium-Range Weather Forecast Interim data. Based on the direction of the topography, the LLF is divided into upslope, downslope, easterly and westerly LLF. The transported moisture from the Amazon to east of the Andes and strength of LLF decides the precipitation characteristics over tropical and mid-latitude PCSs. The zonal variation over the SA continent shows that the easterly and northerly LLF consist of higher fraction of PCSs with largest area (> 2000 km2). The RR and Dm are higher at the eastern flank of SA Andes, and higher RR is observed in northerly and easterly LLF and shows the role of the moisture convergence near the eastern flank of Andes. However, the differences in the near surface rainfall parameters are higher when the LLF direction is considered along the perpendicular direction of the topography. The analysis reveals that mountain and directional LLF can alter the precipitation characteristics, and mostly, the eastern flank of Andes has higher RR and Dm compared to western flank of the Andes, and highest for the orographically moisture loaded upslope and easterly LLF in tropical PCSs. Tropical PCS has higher probability of bright band and warm rain compared to mid-tropical latitude PCSs and even higher in upslope and easterly LLF. The variation in DSD parameters with RR and STH revealed the role of the LLF and complex orography in the microphysical evolution of the precipitation and suggested that it is much required to investigate them in the numerical models.

Highly Sensitive Gold Nanoparticle Polymerase Chain Reaction in the Detection of Anaplastic Lymphoma Kinase-Positive Gastric Cancer from a Biopsy Specimen

Gastric cancer is a malignant tumor that is originated from the epithelia of the gastric mucosa. Although the gastroscopic biopsy of suspicious gastric areas can provide better early-warning opportunities for patients with malignant tumors that result in achieving early diagnosis and treatment, many malignant tumors are still excluded due to atypical histology, sampling errors, nonspecific antibodies, and other reasons, which pose a threat to the physical and mental health of patients. Therefore, more sensitive and specific detection methods of gastric cancer are needed to improve the screening efficiency of gastroscopic biopsy. The sensitivity of nano PCR was 10 times higher than that of conventional PCR. In comparison with the conventional RT-PCR method, nano PCR technology can amplify brighter bands and identify higher gene expression levels for ALK weak positive gastric cancer in IHC, and improve the detection rate of clinical specimens with lower ALK staining. Therefore, nano-gold polymerase chain reaction used gold nanoparticle (nano-gold PCR) has high sensitivity and positive detection rate for ALK-positive gastric cancer identified by gastroscopy. When a low concentration was observed for the amplified gene, especially when the biopsy tissue was too small to carry out IHC staining, the target gene could be amplified more effectively. Therefore, nano PCR technology is proposed to be widely used in target gene detection of biopsy tissue to achieve better tumor screening.

Facial band colour in the mangrove crab Parasesarma peninsulare Shahdadi, Ng & Schubart, 2018 plays a role in mate recognition

Various crab taxa are known to use their external colouration as visual courtship signals. Early research on the mangrove crab Parasesarma peninsulare Shahdadi et al., 2018 indicated a potential role in sexual signalling for its bright blue-green facial bands, which are highly conspicuous against mangrove mud. To advance this work, we conducted experiments investigating both male responses to female stimuli and female responses to male stimuli. Two sets of binary choice experiments were performed—one with live crabs and one using androgyne images where the only sex-specific cue was facial band colour—to test whether the crabs could distinguish between male and female conspecifics based on the colour of their facial band alone, i.e. independent of auditory, chemical and other visual cues. In both cases, the crabs showed a significantly greater preference for conspecifics of the opposite sex (i.e. males preferred females and vice versa). These results provide evidence for colour vision in Parasesarma and suggest that the facial bands are used by the crabs for sexual discrimination and mate recognition.

Rainfall Characteristics in the Mantaro Basin over Tropical Andes from a Vertically Pointed Profile Rain Radar and In-Situ Field Campaign

Information on the vertical structure of rain, especially near the surface is important for accurate quantitative precipitation estimation from weather and space-borne radars. In the present study, the rainfall characteristics, from a vertically pointed profile Radar in the Mantaro basin (Huancayo, Peru) are observed. In summary, diurnal variation of near-surface rainfall and bright band height, average vertical profiles of the drop size distribution (DSD), rain rate, radar reflectivity (Ze) and liquid water content (LWC) are investigated to derive the rainfall characteristics. Diurnal variation of rain rate and bright band height show the bimodal distribution, where frequent and higher rain rate occurred during the afternoon and nighttime, and more than 70% bright band height found between 4.3–4.7 km. The average vertical profiles of Ze show the opposite characteristics above and below the melting level (ML) and depend on the near-surface rain rate. For example, the average Ze profiles have a negative gradient above the ML, whereas below, the ML, the gradient depends on the near-surface rain rate. The rain rate and LWC show the opposite behavior, and both consist of a positive (negative) gradient below (above) the ML. The vertical growth of DSD parameters depend on the near-surface rain rate, and a higher concentration of large-sized of droplets are observed for higher near surface rain rate, however, the dominant modes of droplets are <1 mm throughout the vertical column. However, the most significant variation in DSD growth is observed for near-surface rain rate ≥20 mm/h. These findings suggest using different retrieval techniques for near surface rain estimation than the rest of the vertical profile and high rain rate events. The improved understanding of the tropical Andes precipitation would be very important for assessing climate variability and to forecast the precipitation using the numerical models.

Fingerprinting the Excited-State Dynamics in Methyl Ester and Methyl Ether Anions of Deprotonated para-Coumaric Acid.

Chromophores based on the para-hydroxycinnamate moiety are widespread in the natural world, including as the photoswitching unit in photoactive yellow protein and as a sunscreen in the leaves of plants. Here, photodetachment action spectroscopy combined with frequency- and angle-resolved photoelectron imaging is used to fingerprint the excited-state dynamics over the first three bright action-absorption bands in the methyl ester anions (pCEs-) of deprotonated para-coumaric acid at a temperature of ∼300 K. The excited states associated with the action-absorption bands are classified as resonances because they are situated in the detachment continuum and are open to autodetachment. The frequency-resolved photoelectron spectrum for pCEs- indicates that all photon energies over the S1(ππ*) band lead to similar vibrational autodetachment dynamics. The S2(nπ*) band is Herzberg-Teller active and has comparable brightness to the higher lying 21(ππ*) band. The frequency-resolved photoelectron spectrum over the S2(nπ*) band indicates more efficient internal conversion to the S1(ππ*) state for photon energies resonant with the Franck-Condon modes (∼80%) compared with the Herzberg-Teller modes (∼60%). The third action-absorption band, which corresponds to excitation of the 21(ππ*) state, shows complex and photon energy-dependent dynamics, with 20-40% of photoexcited population internally converting to the S1(ππ*) state. There is also evidence for a mode-specific competition between prompt autodetachment and internal conversion on the red edge of the 21(ππ*) band. There is no evidence for recovery of the ground electronic state and statistical electron ejection (thermionic emission) following photoexcitation over any of the three action-absorption bands. The photoelectron spectra for the deprotonated methyl ether derivative (pCEt-) at photon energies over the S1(ππ*) and S2(nπ*) bands indicate diametrically opposed dynamics compared with pCEs-, namely, intense thermionic emission due to efficient recovery of the ground electronic state.

Relating the Radar Bright Band and Its Strength to Surface Rainfall Rate Using an Automated Approach

AbstractIn radar observations of hydrometeors, the 0°C isotherm in the atmosphere (i.e., the freezing level) usually appears as a region of enhanced reflectivity. This region is known as the bright band (BB). In this study, observations over 12 months from a vertically pointing 35-GHz radar and a collocated disdrometer at the Natural Environment Research Council (NERC) Facility for Atmospheric and Radio Research (NFARR) are used to identify and compare microphysical differences between BB and non-brightband (NBB) periods. From these observations, the relationship between radar reflectivity Z and rainfall intensity R is found to be Z = 772R0.57 for BB periods and Z = 108R0.99 for NBB periods. Additionally, the brightband strength (BBS) was calculated using a novel method derived from the Michelson contrast equation in an attempt to explain the observed variability in BB precipitation. A series of Z–R relationships are computed with respect to BBS. The coefficients increase with increasing BBS from 227 to 926, while the exponents decrease with increasing BBS from 0.85 to 0.38. The results also indicate that NBB periods identified in the presence of a 0°C isotherm in other studies may be misclassified due to their inability to identify weak brightband periods. As such, it is hypothesized that NBB periods are solely due to warm rain processes.

Fine structure of another blue luminescence band in undoped GaN

A blue luminescence band, labeled BL3, has been found in undoped GaN samples grown by hydride vapor phase epitaxy. It has a maximum at 2.8 eV and a phonon-related fine structure at its high-energy side. The zero-phonon line of this band consists of a duplet with two sharp lines at 3.0071 and 3.0147 eV. Three phonon modes, including the LO mode with an energy of 91.3 meV and two pseudolocal phonon modes with energies of 39.6 and 68.2 meV, form the characteristic fine structure of the BL3 band. The BL3 band is attributed to internal transitions from excited states located near the conduction band to the 0/+ transition level of unknown defect. The defect is preliminarily identified as the RY3 center, which is also responsible for bright red-yellow luminescence bands in the studied samples.

Radar Reflectivity of Lightning Flashes in Stratiform Regions of Mesoscale Convective Systems

AbstractA total of 254 flashes observed in 14 mesoscale convective systems in Chongqing, China, during the summers of 2014–2015 was used to investigate the characteristics of lightning flashes in stratiform regions (stratiform lightning flashes). The data were analyzed and combined with data from an S‐band Doppler radar system. The results show that the reflectivity characteristics of stratiform lightning flashes are different from those of convective lightning flashes. More than 90% of the stratiform lightning flashes had close spatial relationship with the areas in which bright bands were identified in the vertical direction. The reflectivity at the first detected veryhighfrequency sources of most stratiform lightning flashes decreased with increasing core reflectivity within the lightning extension area. Further investigations showed that only a small proportion (≤10%) of the stratiform lightning flashes were directly initiated by the charge corresponding to the reflectivity cores. It suggests that the reflectivity cores (mostly bright bands) and stratiform lightning flashes are close in space, but different in causality. Some in situ electrifications in stratiform regions, such as nonriming noninductive electrification and melting electrification, are inferred to cause this relationship. The stratiform lightning flashes initiated from lower altitudes tended to have a lower maximum reflectivity within their lightning areas, but a higher maximum reflectivity in the vertical direction of their initiation locations than flashes initiated at higher altitudes.

Metal Artifact Reduction in X-ray CT via Ray Profile Correction

In computed tomography (CT), metal implants increase the inconsistencies between the measured data and the linear assumption of the Radon transform made by the analytic CT reconstruction algorithm. The inconsistencies appear in the form of dark and bright bands and streaks in the reconstructed image, collectively called metal artifacts. The standard method for metal artifact reduction (MAR) replaces the inconsistent data with interpolated data. However, sinogram interpolation not only introduces new artifacts but it also suffers from the loss of detail near the implanted metals. With the help of a prior image that is usually estimated from the metal artifact-degraded image via computer vision techniques, improvements are feasible but still no MAR method exists that is widely accepted and utilized. We propose a technique that utilizes a prior image from a CT scan taken of the patient before implanting the metal objects. Hence, there is a sufficient amount of structural similarity to cover the loss of detail around the metal implants. Using the prior scan and a segmentation or model of the metal implant, our method then replaces sinogram interpolation with ray profile matching and estimation, which yields much more reliable data estimates for the affected sinogram regions. Experiments with clinical dataset obtained using surgical imaging CT scanner show very promising results.

Utility of Vertically Integrated Liquid Water Content for Radar-Rainfall Estimation: Quality Control and Precipitation Type Classification

Abstract This study proposes a new estimation method for vertically integrated liquid water content (VIL) using radar reflectivity volume data and temperature sounding retrieved from the numerical weather model analysis. This method addresses uncertainty factors in conventional VIL estimation associated with the effects from the bright band (BB) and radar beam geometry near the radar site. The new VIL is then used for precipitation classification (convective/stratiform) and wind turbine clutter detection in the hope that the estimated VIL indicating vertical activities or development of precipitation systems will account for the two independent subjects together, in opposite ways. The non-precipitation radar echoes returned from wind turbines do not likely generate significant degree of VIL, compared to the one estimated from actual convective cells, which contain comparable reflectivity strength. We tested the proposed VIL estimation, precipitation classification, and wind turbine clutter detection methods using various Iowa cases and illustrated their successful application. We also performed a quantitative evaluation of precipitation classification using ground reference data from a dense rain gauge network over the Turkey River basin in Iowa. The evaluation results show improved performance for most non-convective event cases estimated by the stratiform estimator (Z = 200R1.6) because we applied the convective estimator (Z = 300R1.4) to all event cases without classification. In addition, we demonstrated the potential of the new classification to mitigate significant BB effects in quantitative precipitation estimation using a correction method based on the vertical profile of reflectivity.

A Photoetching‐After‐Growth Approach for the Synthesis of Nanocrystal Heterostructures Exhibiting Tunable Dual‐Band Emission

AbstractIntroduced herein is a new strategy for synthesizing sophisticated colloidal semiconductor nanostructures with targeted optical properties by combining a conventional colloidal growth (bottom‐up) process and a postgrowth photoetching (top‐down) process. To demonstrate the utility of such photoetching‐after‐growth approach, a complex quantum dot (QD)–quantum rod (QR) dual quantum‐confined domain nanocrystal heterostructure (NCH) is engineered which exhibits bright dual‐band emission precisely tunable in a broad visible region. (CdSe/CdS)/ZnS/CdSe QD/barrier/multi‐QR NCHs consisting of a single CdSe/CdS QD core and multiple CdSe QR branches with a wide‐bandgap ZnS barrier between them are prepared through a multistep colloidal growth. The as‐synthesized NCHs show a single emission band from QR; however, after photoetching, NCHs begin to display bright dual emission bands, a high‐energy emission band from QR in addition to the low‐energy emission band from QD. While the QD emission at 586 nm is determined by colloidal growth conditions, that of QR emission is precisely tunable in the 500–585 nm range by quantum‐size‐selective photoetching using a wavelength‐tunable laser. Notably, the QR emission bandwidth decreases to ≈20 nm, which is close to that of a single CdSe nanorod, emphasizing a significant quantum‐size‐focusing effect of the photoetching process.

OPTIMASI SUHU ANNEALING UNTUK EMPAT PRIMER RAPD PADA KACANG HIJAU (Vigna radiata L.)

Determination of annealing temperature of the primer is the first step for genetic diversity analysis using molecular markers such as RAPD (Random Amplified Polymorphic DNA). This study aims to determine annealing temperature (Ta) of RAPD primers on Kampar Mungbean. Methods included total DNA extraction, electrophoresis, and annealing temperature optimization of four RAPD markers namely OPD-20, OPI-06, OPI-13, dan OPX-13. Optimization was conducted by reducing the Tm value (Time melting) of each primer with 3 (Tm-3) and 5 (Tm-5). The results showed that the optimization using OPD-20 and OPX-13 produced bands at Tm-3 and Tm-5. Meanwhile, optimization using OPI-06 and OPI-13 resulted in bands at Tm-3. The next step was to choose the exact Ta based on the clear and bright band. In conclusion, exact Ta for OPD-20, OPI-06, OPI-13, and OPX-13 were 36,1°C, 38,1°C, 35,4°C, and 32,5°C respectively.

Mod(n-m,3) Dependence of Defect-State Emission Bands in Aryl-Functionalized Carbon Nanotubes.

Molecularly functionalized single-walled carbon nanotubes (SWCNTs) are potentially useful for fiber optical applications due to their room temperature single-photon emission capacity at telecommunication wavelengths. Several distinct defect geometries are generated upon covalent functionalization. While it has been shown that the defect geometry controls electron localization around the defect site, thereby changing the electronic structure and generating new optically bright red-shifted emission bands, the reasons for such localization remain unexplained. Our joint experimental and computational studies of functionalized SWCNTs with various chiralities show that the value of mod(n-m,3) in an (n,m) chiral nanotube plays a key role in the relative ordering of defect-dependent emission energies. This dependence is linked to the complex nodal characteristics of electronic wave function extending along specific bonds in the tube, which justifies the defect-geometry dependent exciton localization. This insight helps to uncover the essential structural motifs allowing tuning the redshifts of emission energies in functionalized SWCNTs.

Impact of different metal artifact reduction techniques on attenuation correction in 18F-FDG PET/CT examinations.

To evaluate the impact of different metal artifact reduction (MAR) algorithms on Hounsfield unit (HU) and standardized uptake values (SUV) in a phantom setting and verify these results in patients with metallic implants undergoing oncological PET/CT examinations. In this prospective study, PET-CT examinations of 28 oncological patients (14 female, 14 male, mean age 69.5 ± 15.2y) with 38 different metal implants were included. CT datasets were reconstructed using standard weighted filtered back projection (WFBP) without MAR, MAR in image space (MARIS) and iterative MAR (iMAR, hip algorithm). The three datasets were used for PET attenuation correction. SUV and HU measurements were performed at the site of the most prominent bright and dark band artifacts. Differences between HU and SUV values across the different reconstructions were compared using paired t-tests. Bonferroni correction was used to prevent alpha-error accumulation (p < 0.017). For bright band artifacts, MARIS led to a non-significant mean decrease of 12.0% (345 ± 315 HU) in comparison with WFBP (391 ± 293 HU), whereas iMAR led to a significant decrease of 68.3% (125 ± 185 HU, p < 0.017). For SUVmean, MARIS showed no significant effect in comparison with WFBP (WFBP: 0.99 ± 0.40, MARIS: 0.96 ± 0.39), while iMAR led to a significant decrease of 11.1% (0.88 ± 0.35, p < 0.017). Similar results were observed for dark band artifacts. iMAR significantly reduces artifacts caused by metal implants in CT and thus leads to a significant change of SUV measurements in bright and dark band artifacts compared with WFBP and MARIS, thus probably improving PET quantification. The present work indicates that MAR algorithms such as iMAR algorithm in integrated PET/CT scanners are useful to improve CT image quality as well as PET quantification in the evaluation of tracer uptake adjacent to large metal implants. A detailed analysis of oncological patients with various large metal implants using different MAR algorithms in PET/CT has not been conducted yet.

Combined use of volume radar observations and high-resolution numerical weather predictions to estimate precipitation at the ground: methodology and proof of concept

Abstract. The extrapolation of the precipitation to the ground from radar reflectivities measured at the beam altitude is one of the most delicate phases of radar data processing for producing quantitative precipitation estimations (QPEs) and remains a major scientific issue. In many operational meteorological services such as Météo-France, a vertical profile of reflectivity (VPR) correction is uniformly applied over a large part or the entire radar domain. This method is computationally efficient, and the overall bias induced by the bright band is most of the time well corrected. However, this way of proceeding is questionable in situations with high spatial and vertical variability of precipitation (during the passage of a cold front or in a complex terrain, for example). This study initiates from two statements: first, radars provide information on precipitation with a high spatio-temporal resolution but still require VPR corrections to extrapolate rain rates at the ground level. Second, the horizontal resolution of some numerical weather prediction (NWP) models is now comparable with the radar one, and their dynamical core and microphysics schemes allow the production of realistic simulations of VPRs. The present paper proposes a new approach to assess surface rainfall from radar reflectivity aloft by exploiting simulated VPRs and rainfall forecasts from the high-resolution NWP model AROME-NWC. To our knowledge, this is the first time that simulated precipitation profiles from an NWP model are used to derive radar QPEs. The implementation of the new method on two stratiform situations provided significant improvements on the hourly and 6 h accumulations compared to the operational QPEs, showing the relevance of this new approach.

Discernment of near-oceanic precipitating clouds into convective or stratiform based on Z–R model over an Asian monsoon tropical site

Type of precipitating near-oceanic clouds are found out and tracked by inferring it from the near-surface empirical relationships of rainfall rate and radar reflectivity (Z–R), which are established using a micro-rain radar (MRR) and a Joss–Waldvogel disdrometer at a tropical coastal station Thiruvananthapuram (8.5°N, 76.9°E), an Asian monsoon near-oceanic site, almost at the tip of Indian peninsula. It is also found out from the vertical variation of Z–R relation that coalescence is prevalent than breakup, as a result of the collision of rain drops, along with evaporation of smaller drops existed as the rain comes down. The DSD/radar reflectivity/rainfall data from the MRR, disdrometer and manual rain gauge were inter-compared, and found to have good agreement. The MRR radar bright band signature, which is an indication of melting height, is validated using the Wyoming radiosonde data. The whole rain events from March to September 2007 were separated in to bright band (BB) and non-bright band (NBB) cases. The variation of Z with R for all the heights (up to 6000 m with 200 m intervals) is modeled with a function Z = ARb corresponding to both BB and NBB cases, separately for pre-monsoon and southwest monsoon seasons. And, it is realised that there are two distinct fits with different slopes and intercepts existing for Z–R relations corresponding to BB and NBB cases throughout aloft during both the seasons. It is found out that the presence of radar BB or NBB signatures, with corresponding distinct Z–R relations even just at near-surface, which can be used as a proxy for discerning the clouds into stratiform or convective, respectively.

Study on the algorithm to retrieve precipitation based on three-layer structures with X-band synthetic aperture radar

We describe the response of synthetic aperture radar to precipitation normalized radar cross section using a forward scattering model. Based on the snow-layer, rainfall-layer, and zero-layer bright band, the attenuation models of volume scattering and surface scattering echoes are established, and a retrieval algorithm based on a three-layer structure is proposed. The information of the starting point and width of the rainfall area is obtained by data preanalysis, and then the precipitation intensity is inverted by combining the model-oriented statistical and Volterra integral equation methods. The retrieve results in three cases show that the algorithm is scientific and effective, reduces the hypothetical conditions of the model, reduces the error of retrieve of precipitation by bright band, and the retrieved data are accurate and reliable.

Studying the effect of some physicochemical properties of the Bahar Al-Najaf soils / IRAQ on the reflection and absorption characteristics of the Landast 8 bands (OLI, TIRS)

The study was conducted on the Bahar Al-Najaf lands - Iraq in 2016 within the coordinates between the (43º 47−11= - 44º 30−15=) E and (31º 39−16= - 32º 08−08=) N with an area about 2000 km2. 25 surface soil samples by a depth of 15cm were taken within study area, their locations are identified using GPS, They crushed and passed through 2mm sieve openings for some physicochemical analysis: soil grain size distribution, Ec, O.M, PH, gypsum and lime to demonstrate their effects on the reflective and absorptive properties of Landsat 8 sensors bands (OLI, TIRS) which captured on 20-07-2016 and downloaded from the USGS. To deduct study area we use ERDAS imagine 2013 choosing False color Composite RGB (753) with Some improvements (radiation, spectral, spatial) have been made. The laboratory analysis showed that the soils textures ranged between (sandy - clayey), (pH: 7.41-8.37), (OM: 0 - 6.5 g kg−1), (Ec: 1.73 - 177 dsm−1), (Gypsum: 2.67 52.83 g kg−1), (Lime: 13.83 - 620 g kg−1). All locations were highly calcareous, while varied in gypsum content. Spectral Indices values are calculated according to their mathematical formulas, namely BSI, GSI, TCW, NDWI. The gypsum content shows a negative relationship with sand particles, pH, lime, spectral indices and all of Landsat 8 bands except for B2, B3 were positive. While lime content shows positive relationship with all bands, indices and sand particles except for B2 band, NDWI index and the rest soil characteristics studied were negative. Calcareous soils and sandy soils have shown a high reflectivity, indicating the high influencing degree of the lime on the spectral bands comparing to the gypsum effect. A positive correlation relationship between brightness (bands reflectance) and Lime but negative with soil humidity and gypsum. As a negative correlation between Lime and gypsum. The values of the brightness indices BSI, GSI were adopted as indicators for the degree of reflectivity, while the values of absorptive indices TCW, NDWI were used to assess the moisture content and spectral bands absorption. The absorption depth (peak) of the short infrared bands SWI1, SWI2 represented by (B6, B7) respectively were greater than the absorption depth of NIR (B5 band).

Improvements in the Beam-Mismatch Correction of Precipitation Radar Data After the TRMM Orbit Boost

The orbit of the tropical rainfall measuring mission (TRMM) satellite was boosted from 350 to 402.5 km in August 2001 to extend its lifetime by conserving fuel. Since the timing between transmission and reception by the precipitation radar (PR) onboard the TRMM satellite was a fixed constant for measurement from an original altitude of 350 km, the PR encountered a mismatch between the transmitting and receiving beams after the TRMM orbit boost. Although the PR algorithm in TRMM Version 7 employs a correction for the beam mismatch, its error remains as an underestimation of the precipitation estimates near surface in the second half of the swath. This paper aims to mitigate the beam-mismatch correction error in Version 7. The beam-mismatch correction needs to estimate the radar echo that would be measured in the virtual intermediate beam between the beam in question and the previous adjacent beam. The beam-mismatch correction developed in this paper assumes that the surface and precipitation echoes change linearly in the horizontal direction in parallel to the surface between the two beams. The new correction is tested with observational data, indicating that the method improves the accuracy of the correction at off-nadir angles. Statistics of the surface normalized radar cross sections and the bright band peak intensities at off-nadir angles are improved using the method. The asymmetric bias of the precipitation estimates with respect to the scan angle in Version 7 is mitigated by 95.9% over ocean and 72.5% over land with the new correction.

Selecting and optimizing a reliable DNA extraction method for isolating viral DNA in okra (&lt;em&gt;Abelmoschus esculentus&lt;/em&gt;)

Detection and identification of viruses in okra plant is important to manage viral diseases. Good quality of DNA is essential for the PCR based detection and subsequent genomic sequencing. However, the DNA extraction has been greatly affected by mucilaginous substances present in okra plant parts. Objective of this study is to find out an extraction method that can eliminate mucilaginous materials and yield good quality DNA. Five different protocols were tested with okra leaf samples having okra yellow vein mosaic disease (OYVMD) symptoms. Quantity and purity of extracted DNA was tested using Nanodrop spectrophotometer. Precise quantity comparison was done by measuring total plant DNA in relation to the copy number of ACT2 gene using quantitative polymerase chain reaction (qPCR). The extracted DNA samples were used as template for detection of Bhendi yellow vein mosaic virus and Bhendi yellow vein mosaic betasatellite using specific primers. A modified protocol (modified method 1), introduced in this study, produced better yield and quality of DNA compared to other tested protocols. The method yielded 32 μg DNA for 100 mg leaf powder and the ratios A260/A280 and A260/A230 were 1.8 and 2.1, respectively. The qPCR quantification further confirmed higher quantity of DNA yield in this modified protocol. End point PCR with virus specific primers yielded very bright bands for Bhendi yellow vein mosaic virus and Bhendi yellow vein mosaic betasatellite. In conclusion, the modified method 1 can be used to extract good quality and quantity of DNA from okra.