Increase In Brightness Research Articles

The stellar mass Fundamental Plane: the virial relation and a very thin plane for slow rotators

ABSTRACT Early-type galaxies – slow and fast rotating ellipticals (E-SRs and E-FRs) and S0s/lenticulars – define a Fundamental Plane (FP) in the space of half-light radius Re, enclosed surface brightness Ie, and velocity dispersion σe. Since Ie and σe are distance-independent measurements, the thickness of the FP is often expressed in terms of the accuracy with which Ie and σe can be used to estimate sizes Re. We show that: (1) The thickness of the FP depends strongly on morphology. If the sample only includes E-SRs, then the observed scatter in Re is $\sim 16{{\ \rm per\ cent}}$, of which only $\sim 9{{\ \rm per\ cent}}$ is intrinsic. Removing galaxies with M* < 1011 M⊙ further reduces the observed scatter to $\sim 13{{\ \rm per\ cent}}$ ($\sim 4{{\ \rm per\ cent}}$ intrinsic). The observed scatter increases to $\sim 25{{\ \rm per\ cent}}$ usually quoted in the literature if E-FRs and S0s are added. If the FP is defined using the eigenvectors of the covariance matrix of the observables, then the E-SRs again define an exceptionally thin FP, with intrinsic scatter of only 5 per cent orthogonal to the plane. (2) The structure within the FP is most easily understood as arising from the fact that Ie and σe are nearly independent, whereas the Re−Ie and Re−σe correlations are nearly equal and opposite. (3) If the coefficients of the FP differ from those associated with the virial theorem the plane is said to be ‘tilted’. If we multiply Ie by the global stellar mass-to-light ratio M*/L and we account for non-homology across the population by using Sérsic photometry, then the resulting stellar mass FP is less tilted. Accounting self-consistently for M*/L gradients will change the tilt. The tilt we currently see suggests that the efficiency of turning baryons into stars increases and/or the dark matter fraction decreases as stellar surface brightness increases.

Radiative Transfer Modeling of EC 53: An Episodically Accreting Class I Young Stellar Object

Abstract In the episodic accretion scenario, a large fraction of the protostellar mass accretes during repeated and large bursts of accretion. Since outbursts on protostars are typically identified at specific wavelengths, interpreting these outbursts requires converting this change in flux to a change in total luminosity. The Class I young stellar object EC 53 in the Serpens Main cloud has undergone repeated increases in brightness at 850 μm that are likely caused by bursts of accretion. In this study, we perform two- and three-dimensional continuum radiative transfer modeling to quantify the internal luminosity rise in EC 53 that corresponds to the factor of ∼1.5 enhancement in flux at 850 μm. We model the spectral energy distribution and radial intensity profile in both the quiescent and outburst phases. The internal luminosity in the outburst phase is ∼3.3 times brighter than the luminosity in the quiescent phase. The radial intensity profile analysis demonstrates that the detected submillimeter flux variation of EC 53 comes from the heated envelope by the accretion burst. We also find that the role of external heating of the EC 53 envelope by the interstellar radiation field is insignificant.

Subsequent outbursts of the same EXor source possibly present similar features

Context. V1118 Ori is a classical EXor source whose light curve has been monitored, although not continuously, over the past 30 years. This source underwent a powerful outburst in 2005, followed by 10 years of quiescence and a less intense outburst in 2015. In 2019, a new intense brightness increase was observed (Δg ∼ 3 mag). Aims. This new accretion episode offers the opportunity to compare the photometric and spectroscopic properties of multiple outbursts of the same source. This allows us to highlight the differences and similarities among various events by removing any possible bias related to the intrinsic properties of the star-disk system. Methods. We discovered the 2019 V1118 Ori outburst by examining the g-band light curve acquired by the Zwicky Transient Facility and followed the declining phase with the Rapid Eye Mount telescope in the griz bands. Two near-infrared spectra were also acquired at different brightness stages with the Large Binocular Telescope. Results. The last event shows the following characteristics: (1) an amplitude similar to that of 2015 and lower than that of 2005; (2) a duration of less than one year as in previous events; (3) a increasing (decreasing) speed of 0.018 (0.031) mag day−1, which is different from previous cases; (4) a gradually blueing of the [g − r] color is observed over time, while the [r − i] color remains roughly unchanged; (5) with few exceptions, the near-infrared lines (mainly H I recombination) are the same as those observed in 2015; and (6) the mass accretion rate peaks at Ṁacc ∼ 10−7 M⊙ yr−1 and decreases in about a month down to a few 10−8 M⊙ yr−1. Conclusions. Our analysis shows that the comparison of data from different outbursts of the same source is a nontrivial exercise, which allows us to obtain important clues that are useful to drive theoretical efforts toward a better understanding of the EXor phenomenon.

A High Throughput Approach to Biochemically Characterizing Firefly Luciferase for Use in Multi‐Component Bioluminescent Imaging

Bioluminescent imaging (BLI) is a foundational tool for in vivo imaging routinely used to accurately visualize cells within mouse bodies and brains. However, these probes are currently limited in their ability to image multiple targets at once as well as by their brightness. While directed evolution is commonly used to improve these enzymes, it is a slow approach and is often limited by a lack of biochemical knowledge to guide amino acid changes. Here, to rapidly generate high‐value biochemical information on the enzyme luciferase, we have developed a high‐throughput platform to categorize substrate recognition and brightness for many possible amino acid changes in a single experiment. Our approach couples screening small libraries followed by next‐generation sequencing to rapidly create sequence‐function maps. As an initial foray, we screened all mutations at three amino acid positions—A482, N229, and G246; as expected, each position showed unique patterns for their impact on function. Generally, mutations at the 482 position resulted in either inactivation of the protein or no change or slight decrease in function, while mutations at the 229 position resulted in decrease in function and a large shift towards red light emission, and mutations at the 246 position resulted in inactivation of the protein except for a handful of mutants that showed increased functionality. In addition, two mutants, N229G and G246S, were observed to have an increase in brightness with a modified luciferin substrate accompanied by a small decrease in brightness with the natural substrate, resulting in a specificity shifted towards the analogous substrate without compromised brightness. Collectively, these data illustrate that our novel, high‐throughput approach is reliable in creating diverse libraries of mutants and detecting true enrichment in function. In addition, we have identified a handful of mutants at two of the three residues investigate here that have improved brightness with non‐native substrates. This approach can be used to rapidly build a sequence‐function map at any amino acid position, facilitating future protein engineering and improving our basic biochemical understanding of this important enzyme.Support or Funding InformationFunding for this research has been provided by the Research Corporation for Science Advancement.

On the Magnetospheric ULF Wave Counterpart of Substorm Onset

AbstractOne near‐ubiquitous signature of substorms observed on the ground is the azimuthal structuring of the onset auroral arc in the minutes prior to onset. Termed auroral beads, these optical signatures correspond to concurrent exponential increases in ground ultralow frequency (ULF) wave power and are likely the result of a plasma instability in the magnetosphere. Here, we present a case study showing the development of auroral beads from a Time History of Events and Macroscale Interactions during Substorms (THEMIS) all‐sky camera with near simultaneous exponential increases in auroral brightness, ionospheric and conjugate magnetotail ULF wave power, evidencing their intrinsic link. We further present a survey of magnetic field fluctuations in the magnetotail around substorm onset. We find remarkably similar superposed epoch analyses of ULF power around substorm onset from space and conjugate ionospheric observations. Examining periods of exponential wave growth, we find the ground‐ and space‐based observations to be consistent, with average growth rates of ∼0.01 s−1, lasting for ∼4 min. Cross‐correlation suggests that the space‐based observations lead those on the ground by approximately 1–1.5 min. Meanwhile, spacecraft located premidnight and ∼10 RE downtail are more likely to observe enhanced wave power. These combined observations lead us to conclude that there is a magnetospheric counterpart of auroral beads and exponentially increasing ground ULF wave power. This is likely the result of the linear phase of a magnetospheric instability, active in the magnetotail for several minutes prior to auroral breakup.

Sensor Technology for Night Sky Brightness Measurements in Malaysia

Artificial light at night is apparently showing to be a major contributor to the increase of sky brightness at night. The natural darkness in large regions of the world including Malaysia currently is at risk. Hence, some Night Sky Brightness (NSB) measurements in Malaysia were conducted by using several types of light sensors in order to serve quantitative data and spread awareness on this issue. This paper aims to analyze the sensor technology that have been used in night sky brightness measurement in Malaysia as well as to identify recent or significant advances and discoveries in this field of study. In this paper, the author adopted qualitative method through literature review from numerous conducted studies by other researchers in order to perceive better understanding on the use of dedicated light sensor in NSB related research. Starting from 2005 until now, it is noticeable that most of the light sensor used in the NSB studies in Malaysia was Sky Quality Meter (SQM) photometer, equipped with TSL237 sensor which has high irradiance responsivity 2.3kHz/(μW/cm2) @ λp = 524nm and 5 Milion:1 input dynamic range as well as able to sense down to 0.00002 Lux and has typical dark frequency down to 0.1 Hz. The result indicates the relative frequency of the SQM usage in NSB studies was 76% compared to PBM, APC, PMT and CDD of only 4% respectively. SQM has always been the choice of researchers in Malaysia to carry out their sky brightness measurements due to user-friendly implementation besides its reliable data obtained from TSL237 sensor which capable to convert the light directly to frequency without an amplifier or data converter. Thus, the nonlinearities and voltage offsets in the data can be circumvented. A fairly good development of sensor that have been utilized in NSB studies can be discerned patently besides NSB studies will always look forward for a better sensor to further enhance the efforts to map sky brightness for preserving the potential dark sky areas for the sake of astronomy.

Solution-processed blue quantum-dot light-emitting diodes based on double hole transport layers: Charge injection balance, solvent erosion control and performance improvement

Abstract Solution processed quantum-dot based light emitting diodes (QLEDs) usually suffer from the issues of imbalanced carrier injection (especially for blue QLEDs) and solvent erosion, which prevents these devices from reaching high performance. Here we report a simple and effective method of promoting hole injection and mitigating solvent erosion simultaneously for fabricating high-performance blue QLEDs. Poly [(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(p-butylphenyl))-diphenylamine)] (TFB)/Lithium bis(trifluoromethanesulfonimide) (Li-TFSI)-doped poly(9-vinlycarbazole) (PVK) bi-layers with smooth surfaces/interfaces, prepared via a solution-process by utilizing 1,4-dioxane as the solvent for PVK, were used as hole transport layers (HTLs) for improving the performance of blue QLEDs. The TFB/Li-doped PVK based QLED records 5829 cd/m2 of maximum brightness and 5.37% of peak EQE, which represents 1.1-fold increase in brightness and ~11.5-fold increase in EQE as compared with the devices based on TFB-only HTLs. The enhanced performance for these TFB/Li-doped PVK based QLEDs can be ascribed to more efficient hole injection offered by Li-doped bilayer HTLs with smooth surfaces/interfaces and stepwise energy level alignment. The CIE 1931 color coordinates (0.15, 0.03) for these TFB/Li-doped PVK based QLEDs are close to the National Television System Committee (NTSC) standard blue CIE coordinates, showing promise for use in next-generation full-color displays. This work provides a facile solution method of fabricating TFB/Li-doped PVK bi-layers with smooth surfaces/interfaces and proves the superiority of these TFB/Li-doped PVK bi-layered HTLs in hole transport and injection for high-performance blue QLEDs.

A photometric mapping of the night sky brightness of the Maltese islands

Over the years, the Maltese Islands have seen a marked rise in the prevalence of artificial lighting at night. The most evident type of light pollution arising from this evolution in anthropogenic night-time lighting is artificial skyglow via partial back-scattering in the atmosphere, leading to an increase in the Night Sky Brightness (NSB). The importance of understanding and quantifying the geographical distribution of the NSB is underscored by the adverse impact of light pollution on various spheres, from astronomical observation to ecology and human health. For the first time, we present a detailed map of the NSB over the Maltese archipelago carried out with Unihedron Sky Quality Meters. We show that the vast majority of the area of the Maltese Islands is heavily light polluted, with 87% of the area registering a NSB < 20.39magSQM/arcsec2 (Bortle Class 5 or higher) and 37.3% < 19.09magSQM/arcsec2 (Bortle Class 6 or higher), with the Milky Way being visible for only 12.8% of the area (adopting a visibility threshold > 20.4 - 21.29magSQM/arcsec2; Bortle Class 4). Coastal Dark Sky Heritage Areas on the island of Gozo retain generally darker skies than the rest of the islands, but light pollution originating further inland is encroaching upon and adversely affecting these sites. The methodology presented in this study can be adopted for continued future studies in Malta as well as for other regions.

Enhanced laser–plasma interactions using non-imaging optical concentrator targets

Picosecond-scale laser–matter interactions using compound parabolic concentrators have demonstrated strongly relativistic ponderomotive effects with ∼ 10 × increase in x-ray source brightness, positron production and multi-MeV proton acceleration versus flat targets, using a marginally relativistic intensity laser.

Bio-degumming of banana fibers using eco-friendly crude xylano-pectinolytic enzymes

In this study, the efficacy of xylano-pectinolytic enzymes in scouring of banana fibers has been reported. Maximum efficiency of bioscouring was recorded using xylanase and pectinase doses of 15 and 4.8 IU, respectively (produced by a bacterial isolate) at a material-to-liquor proportion of 1:25 having 8.5 pH, treatment time of 1 h, speed of 50 rpm, temperature 50 °C, 3 mM EDTA and 1% Tween-80, with maximum sugar release, enhanced fiber water absorbing power and the finest optical characteristics. Enzymatic treatment resulted in 13.27% increase in whiteness, 16.14% increase in brightness and 8.63% decrease in yellowness as compared to raw banana fibers. The bioscouring also resulted in 50% reduction in scouring chemicals, in order to achieve the similar optical characteristics as obtained by the chemically treated fibers with 100% scouring and bleaching. It decreased the consumption of environment polluting chemicals and energy. Therefore, this has proven to be an environment safe method for removing the non-cellulosic impurities. This is the first report mentioning the scouring of banana fibers using xylano-pectinolytic enzymes.

Strategies for Tumor Hypoxia Imaging Based on Aggregation-Induced Emission Fluorogens.

Hypoxia, as a crucial characteristic of cancer, has become an extremely significant direction for researchers to construct fluorescent probes for early diagnosis of tumors. Aggregation-induced emission fluorogens (AIEgens) possess many superior properties to those of conventional fluorophores due to aggregation-induced emission (AIE) features, such as a linear concentration-dependent increase in brightness, remarkable resistance to photobleaching, and the long-term tracking and imaging of cells. Constructing hypoxic response AIEgen-based probes will be very useful for the early diagnosis of tumors. Herein, several hypoxia-responsive probes based on AIEgens reported in the last three years are reported; these examples may lead to the construction of hypoxia-responsive AIE probes used for tumor hypoxia imaging in the future. In addition, typical, conventional hypoxia-responsive bioprobes are presented to further understand hypoxia-responsive fluorescent probes based on AIEgens.

High-performance full-solution-processed quantum dot light-emitting diodes with a doped hole injection layer

<p indent="0mm">Full solution-processed quantum dot light-emitting diodes are the potential ones for future flat panel displays and solid state lighting. The imbalance of holes and electrons due to the larger hole injection barrier is still the critical obstacle for full solution-processed quantum dot light-emitting diodes with high performance. Therefore, improving the hole injection level is the first consideration for us. In this paper, we doped graphene oxide into PEDOT:PSS (volume ratio: 1:2) to form hole injection layer PEDOT:PSS-GO, and then fabricated the high-efficiency full solution-processed quantum dot light-emitting diodes with inverted architecture: ITO/ZnMgO/QDs/PVK/PEDOT:PSS-GO/Al. The maximum brightness of <sc>51392 cd/m²,</sc> and peak current efficiency of <sc>7.60 cd/A</sc> were achieved, showing about 1.3 fold improvement compared to the reference ones. Meanwhile, the conventional ones: ITO/PEDOT:PSS-GO/PVK/QDs/ZnMgO/Al, also fabricated by the same mean, exhibited 0.29 fold increase in maximum brightness. The above results demonstrate that the introduction of GO is beneficial for both normal and inverted full solution-processed quantum dot light-emitting diodes, and is a more effective method for high-performance full solution-processed quantum dot light-emitting diode with inverted structure.

On the Radiative Relaxation Time for the Hydrogen–Helium Atmosphere Estimated from Changes in the Activity Factor of Jupiter’s Hemispheres

The subsolar point on Jupiter’s magnetosphere changes its position by an angle of approximately 26° over the orbital period of Jupiter, which induces seasonal variations in physical and optical characteristics of the planetary atmosphere. At the time close to the summer solstice for the northern hemisphere, Jupiter is in perihelion. Consequently, due to the significant orbital eccentricity, the energy influx into the atmosphere in the northern hemisphere is 21% larger than that in the southern one. This leads to the asymmetry in the meridional distribution of the reflectance of visible clouds. Analysis of the results of photometric observations of Jupiter for 1960–2019 showed that the ratio AJ = BN/BS adequately describes the activity of atmospheric processes on Jupiter, which shows periodic increases in brightness at tropical and temperate latitudes in the southern and northern regions by turn during one orbital period of Jupiter. The response of the atmosphere to changes in the irradiation by the Sun does not occur instantaneously but with some delay. The results of observations of Jupiter in the visible range in 1960–1995 and 2012–2019 show a synchronous delay of 3.4 year (τR ≈ 1.07 × 108 s) in response to the 21% change in the irradiation of different hemispheres when the planet is orbiting the Sun. In 1995–2012, the discrepancy caused by the orbital motion of the planet was observed between the behavior of AJ, the solar activity index Sn, and Jupiter’s regime of exposure to the Sun. Variations associated with the influence of solar activity are mainly induced by significant changes in the ultraviolet radiation of the Sun. These changes first affect the energetics of the upper atmosphere of Jupiter, after which they are indirectly transmitted into the troposphere, sometimes reducing the value of the relaxation constant τR to ~2.5 years. Since 2012, the behavior of the time dependence of AJ, the index of solar activity, and the irradiation regime of Jupiter due to its orbital motion have become consistent again. The periodicity in changes of the photometric characteristics of the northern and southern hemispheres of Jupiter were also restored.

COMPARISON OF NIGHT SKY BRIGHTNESS ABOVE ZAGREB AND A NEARBY RURAL LOCATION 2014-2017

The results of monitoring light pollution near the center of Zagreb at the Faculty of Mining, Geology and Petroleum Engineering (RGN) for the period 2012 - 2017 were presented in a recent article (Andreic, 2018). The question that re- mained unanswered is how the night sky brightness behaves in the suburbs of Zagreb and in the nearby rural area. This article attempts to give some answers to this question by analyzing data gathered at the rural site of Merenje, located north of Zagreb. The main conclusion drawn is that the night sky brightness at both sites follows very similar patterns for clear sky conditions and is often similar for cloudy conditions, too. For both sites, no significant increase in zenithal night sky brightness was found in the observed period of 2014 - 2017. Thus, at least for the areas north of Zagreb that are in the shadow of Medvednica Mountain, the contribution of the light pollution from Zagreb and its growing outskirts remains unaltered. The main difference is in the level of the night sky brightness, the average for the RGN site being 16.9 mag/ arcsec2 and 18.9 mag/arcsec2 for the Merenje site. Additionally, the cloudy conditions enhance the light pollution of Za- greb a lot more, the difference being about 3.2 mag/arcsec2 for RGN, in contrast to 1.9 mag/arcsec2 for the Merenje site. No measurements exist for areas to the south, so no conclusions can be made for the situation there. Last, but not least, it was found that in cloudy conditions, the stronger light pollution of Zagreb is proportionally more enhanced by the clouds/fog than the smaller levels of light pollution at the Merenje site.

Application of Synthetic Peptides to Improve Parameters of Skin Physiology: An Open Observational 30-Day Study

We describe a novel, non-invasive peptide-based product intended to counter several pathophysiological signs of aged skin through the topical application of signalling molecule mimics. Several aesthetic parameters of skin physiology were assessed. The product was tested on 20 healthy Caucasian women (35 - 55 years-old) who applied the product twice-daily to the face for 30 days. Skin elasticity, firmness, sagging, brightness, and luminosity were assessed. Additionally, over a period of 3 hours, the hydrating effect of the product vs placebo vs non-treated skin was assessed. After 30 days, participants showed significant increases in skin elasticity (11.8% increase, p < 0.01), luminosity (2.5% increase, p < 0.01), and brightness (110% increase, p < 0.001) with concomitant significant decreases in skin sagging (6.3% decrease, p < 0.05). The product gave a rapid and sustained hydrating action that was significantly greater than placebo alone (10.2% increase, p < 0.05). No adverse reactions were reported. Cosmetic products based on the action of synthetic peptide mimics of endogenous signalling molecules show promise for combatting the pathological degradation of skin as seen in the elderly. Strategies to reverse these symptoms through non-invasive techniques warrant further investigation. This study provides support for the application of peptides to combat signs of aging and to improve the general condition of the skin.

Feature Point Extraction and Tracking Based on a Local Adaptive Threshold

Navigation, environment perception and localization are important capabilities of intelligent vehicles. In this paper, environmental perception and localization from binocular vision are studied. First, an outdoor feature point extraction algorithm that uses a local adaptive threshold is proposed to acquire environmental information. The algorithm filters feature points by setting adaptive parameters and calculating each pixel threshold with a dynamic local threshold. Second, an accurate method for feature point tracking is proposed for localization. We present exhaustive evaluation in 4 major scenarios from the most popular datasets. Evaluating the proposed method with traditional and state-of-the-art extraction methods and experimental results demonstrates that when the brightness decreases or increases, the performance of the proposed method is stable in terms of the number of feature points, the calculation speed and the overall repetition rate. Our proposed tracking method outperforms state-of-the-art tracking methods in terms of the root mean square error (RMSE) and the errors in the dimensions in the scenarios.

Effect of Ozonation on the Properties of Dry and Moisturized Bread Wheat Grain with and without Bran

The effects of ozone gas on the color, pH and gelatinization properties of dry and moisturized bread wheat grain with and without bran were investigated in present study. Dry and wetted grain samples were ozonated for 2 hours at 18oC. Ozonation increased the brightness for both dry and wet grains with and without bran. Presence of high moisture caused more increase in brightness for samples without bran after ozonation. Ozone gas decreased redness of wheat grains with and without bran. Moisturizing caused the more decrease in redness for samples without bran after the ozone process. Ozonation of dry wheat grains both with and without bran resulted in yellowness decrease, while wet wheat grains both with and without bran were not affected by ozonation process. Ozone gas caused the sharp decrease in the pH value of grain samples especially in the presence of moisture. Onset and peak temperatures of ozonated wheat grains with bran increased significantly for both dry and wet samples while the enthalpy was reduced only for wet sample with bran. However, any significant change in onset temperature, peak temperature and enthalpy was not determined for both dry and moisturized wheat grains without bran after ozonation process.

Clinical evidences of benefits from an advanced skin care routine in comparison with a simple routine.

The use of a skin care routine is commonly promoted by the cosmetic industry, yet there is a lack of clinical evidence to support this practice over the use of a single skin care product. In the present study, we aimed at showing the clinical benefits of using a comprehensive skin care routine vs a simple one. Skin micro-/macro-topographic, skin color, and superficial/deep hydration were collected at baseline and after 4weeks of use, on forty-nine women randomly allocated to two groups. The first one followed the use of an advanced routine (AR: Cleanser/Toner/Eye cream/Serum/Day & Night cream), while the other group was instructed to use a simple routine (SR: Cleanser & Day cream). Hemoglobin heterogeneity was found to be significantly reduced only in the SR group. However, the AR outperformed the SR when it comes to improving superficial hydration, deep hydration, skin roughness, mean pore area, melanin heterogeneity, and crow's feet wrinkle depth. A significant increase in skin brightness from baseline was only recorded when using the AR while both routines significantly improved the nasolabial wrinkles. These findings advocate for using a relevant daily routine as it demonstrates the visible skin benefits over a short period, while driving the creation of habits for the prevention of aging signs.

Thermal Bremsstrahlung of Local Sources Over Solar Spots Based on Microwave Observations

The paper presents the results of a study of microwave thermal bremsstrahlung of local sources above sunspots. Special attention is paid to the transition from thermal bremsstrahlung to the dominant gyroresonance radiation in the high-frequency part of the spectrum of 12–20 GHz (1.5–2.5 cm). At high frequencies, for which the magnitude of the magnetic field is not enough to generate gyroresonance radiation, thermal bremsstrahlung is the main factor. The presented calculations demonstrate an increase in brightness in an extraordinary mode and a decrease in its intensity in an ordinary mode, as well as corresponding examples of observations. The possibilities and advantages of determination of the field with one polarization corresponding to ordinary radiation are revealed. The studied spectral-polarization features of the radiation, estimates of the effective radiation height, and the characteristic features of the change in the sizes of sources with the wave frequency will make it possible to correctly interpret the observations and to improve the accuracy of magnetic field measurement and the diagnostics of the transition region temperature.

Detection of urban flood inundation using RISAT-1 SAR images: a case study of Srinagar, Jammu and Kashmir (North India) floods of September 2014

Microwave data from SAR (synthetic aperture radar) sensors are used extensively in providing operational support for riverine floods, unlike for urban flood disaster. Current approaches for flood mapping using SAR basically aim at detecting for regions of low backscatter due to specular reflection from water surface. However, flooding in urban areas may appear bright in SAR images, because of the enhancement of the double-bounce effect. The present communication presents a case study of the use of moderate-resolution C-band SAR images from Indian Remote Sensing Satellite RISAT-1 to assess the changes in backscattering coefficient (σ0) values (flood σ0 − non-flood σ0) for catastrophic floods of September 2014. SAR images considered for evaluation are with similar acquisition parameters (orbit, look direction, incidence angle, polarization, imaging mode, resolution, and acquisition time) to have a consistency in comparison of backscatter values. From the backscattering coefficient (σ0) comparison analysis and visual inspection between pre-flood and flood duration images, it is observed that there is a significant increase in the σ0 values of about 8.0 dB and corresponding increase in the tonal brightness of flooded locations. The areas identified with high backscatter response are also validated for flooding through high-resolution Pleiades (spatial resolution 0.5 m) optical satellite data and ground information from open sources. The observations made from this study highlight the fact that moderate-resolution SAR images could be an important source in indicating urban flooded areas during rapid response.