Ray Counts Research Articles

Five new species of Parapercis (Perciformes: Pinguipedidae) from southeast Asia and northwest Australia

Five new species of sandperch (Pinguipedidae: Parapercis) from southeast Asia and northwest Australia are described. Parapercis soliorta sp. nov., known from a single specimen acquired from the Iloilo Central Market, taken off Iloilo, Panay Island, Philippines, is readily distinguished by a unique colour pattern including a series of nine brilliant yellow-ringed red spots along the body and caudal fin. Parapercis rubricaudalis sp. nov. is described from 15 specimens trawled between Dampier and Cape Leveque, Western Australia in 70–119 m and a single specimen taken by aquarium fish collectors off Zambales, Luzon, Philippines. It has the posterior end of the opercular ridge armed with two or three strong spines, the margin of the preopercle, subopercle and interopercle strongly serrated, and colouration including six broad irregular orange to reddish bands across the body, and the pelvic fins and lower third of the caudal fin crimson-red. A complex of three closely related species, Parapercis flavipinna sp. nov. from the Philippines, Parapercis caudopellucida sp. nov. from Myanmar and Parapercis hoi sp. nov. from northwest Australia and the Philippines, share a series of six or seven irregular dusky double blotches along the sides, a series of small black spots along the base of the soft dorsal-fin, a pair of dusky blotches on the caudal-fin base, and mostly similar meristic values. Parapercis hoi sp. nov. is known from four specimens trawled off Broome, Western Australia, in 97–109 m and one specimen trawled in the Sibuyan Sea, Philippines, in 73–84 m. It may be distinguished from its two closest congeners by cycloid cheek scales, a distinctive anal-fin colouration, and lower pectoral-fin ray, gill raker and lateral-line scale counts. Parapercis caudopellucida sp. nov., trawled in 125–129 m in the Andaman Sea off southern Myanmar, is described from two specimens. It differs from its two closest congeners most obviously by cycloid cheek scales, caudal-fin colouration, and the presence of a dusky bar extending posteroventrally from the tip of the maxilla to the anteroventral edge of the preopercle. Parapercis flavipinna sp. nov. is described from two specimens acquired from the Iloilo Central Market, taken off Iloilo, Panay Island, in the Philippines. It is distinguished most readily by the presence of ctenoid cheek scales and colouration including rows of bright yellow spots on the anal and caudal fins, a yellow upper lip, a series of yellow streaks and spots on the head, and fleshy pectoral-fin base with a large dark purplish grey blotch followed by a distinct white-edged black bar.

A new species of the clingfish genus Trachelochismus from bay and estuarine areas of New Zealand (Teleostei: Gobiesocidae)

Trachelochismus aestuarium, new species, is described on the basis of 120 specimens, 10.1–45.5 mm SL, collected from shallow (0–29 meters depth) bay and estuarine areas along the coast of New Zealand. It is distinguished from congeners (T. melobesia and T. pinnulatus) by a combination of characters, including features of the cephalic sensory system, adhesive disc papillae, and colouration in life, head shape, and gill-raker, fin ray and vertebrae counts. Phylogenetic analyses of mitochondrial loci (cytrochrome c oxidase subunit 1 and 12S ribosomal RNA) and one nuclear locus (zic family member 1) for all three species of Trachelochismus and two outgroup taxa resulted in phylogenetic hypotheses in which T. aestuarium is the sister taxon to either T. pinnulatus (mitochondrial loci) or T. pinnulatus + T. melobesia (ZIC1). A new terminology is introduced for the superficial neuromasts arranged in rows on the surface of the head in members of Trachelochismus.

Determination of attenuation parameters and energy absorption build-up factor of amine group materials

We have computed radiological parameters of some C- H- N- O based amine group bio material in the energy range 122–1330keV with the gamma ray count by narrow beam geometry. The NaI(Tl) detector with 8K multichannel analyser was used having resolution 6.8% at 663keV. The energy absorption buildup factor (EABF) was determined by using Geometric Progression (G-P) fitting method up to penetration depth of 40mfp at energy 0.015–15MeV. The NIST XCOM data were compared with the experimental value and we observed (3–5%) difference. The comparative study of effective atomic number and effective electron density in the energy range 122–1330keV using Gaussian fit for accuracy were performed. The amino acid has the highest EABF value at 0.1MeV and the variation in EABF with penetration depth up to 1–40 mean free path (mfp). The calculated radiological data of biological material are applicable in medical physics and dosimetry.

Skeletal ontogeny of the vertebral column and of the fins in shi drum Umbrina cirrosa (Teleostei: Perciformes: Sciaenidae), a new candidate species for aquaculture.

The osteological development of the vertebral column and fins in shi drum Umbrina cirrosa was studied in order to improve knowledge for its introduction in Mediterranean aquaculture. The osteological development was studied in 171 individuals, of total length (LT ) from 2·7 to 30·2 mm that were reared under the mesocosm technique. Vertebral ontogeny starts at 3·4 and 4·0 mm LT , with the formation of the first cartilaginous neural and haemal arches, and spines, respectively, and is completed with the full attainment of epicentrals (12·5 mm LT ). The formation of vertebral centra occurs between 4·1 and 7·4 mm LT . Pectoral supports are the first fin elements to develop (3·0 mm LT ), followed by those of the caudal fin (3·8 mm LT ), pelvic fin (3·9 mm LT ) and finally by those of the dorsal and anal fins (4·5 mm LT ). The caudal fin is the first to develop fin rays and attain the full count of principal fin rays (4·5-6·8 mm LT ), but the last to be fully completed with the formation of procurrent fin rays (6·9-17·5 mm LT ). The next fins starting to present rays are the dorsal (5·3 mm LT ) and the pectoral fins (5·6 mm LT ), while the anal and pelvic fins are the last (5·7 mm LT ). Following the caudal principal fin rays (6·8 mm LT ), the dorsal, anal (6·9 mm LT ), pelvic (7·4 mm LT ) and pectoral fins (9·8 mm LT ) are the next with fully completed ray counts. Aggregation of qualitative changes, such as the appearance of cartilages, the beginning and the complement of the ossification process and the full complement of elements in U. cirrosa were measured as cumulative frequency counts. These measurements reveal three ontogenetic intervals: one very developmentally active period during early life stages (from 3 to 5·9 mm LT ), a second slower developmental period (from 6·0 to 8·9 mm LT ) and finally a period of ontogeny more focused on structure refinement up to metamorphosis and settlement (>9·0 mm LT ).

Review of Schismatogobius (Gobiidae) from Japan, with the description of a new species

Three species of Schismatogobius de Beaufort 1912, distinguished by their morphology and mitochondrial DNA sequences, were found in freshwater streams in the Ryukyu Archipelago, Japan. Although two species were previously known from Japan (S. roxasi Herre 1936 and S. ampluvinculus Chen, Shao, and Fang 1995), the taxonomy needs to be revised. To identify these species, the holotype morphology of S. marmoratus (Peters 1868), S. bruynisi de Beaufort 1912, and S. roxasi, originally described from the Philippines and Indonesia, were examined and re-described here, because relatively little information about their diagnostic characters was provided in the original descriptions. The three Japanese species were identified as S. ampluvinculus, S. marmoratus, and a new species. They were distinguished from each other and from their congeners by the banding pattern of the body, markings on the pectoral fins, pigment patterns on the ventral surface of the head and pelvic fin, body depth at the pelvic-fin origin, pre-anal length, and pectoral-fin ray counts. Although the new species had been regarded as S. roxasi in previous publications, we show that it is actually not S. roxasi and that it also differs from all other nominal species of Schismatogobius. This is described as a new species, S. ninja. Additionally, this is the first record of S. marmoratus from Japan.

Synchronization of Human Autonomic Nervous System Rhythms with Geomagnetic Activity in Human Subjects.

A coupling between geomagnetic activity and the human nervous system’s function was identified by virtue of continuous monitoring of heart rate variability (HRV) and the time-varying geomagnetic field over a 31-day period in a group of 10 individuals who went about their normal day-to-day lives. A time series correlation analysis identified a response of the group’s autonomic nervous systems to various dynamic changes in the solar, cosmic ray, and ambient magnetic field. Correlation coefficients and p values were calculated between the HRV variables and environmental measures during three distinct time periods of environmental activity. There were significant correlations between the group’s HRV and solar wind speed, Kp, Ap, solar radio flux, cosmic ray counts, Schumann resonance power, and the total variations in the magnetic field. In addition, the time series data were time synchronized and normalized, after which all circadian rhythms were removed. It was found that the participants’ HRV rhythms synchronized across the 31-day period at a period of approximately 2.5 days, even though all participants were in separate locations. Overall, this suggests that daily autonomic nervous system activity not only responds to changes in solar and geomagnetic activity, but is synchronized with the time-varying magnetic fields associated with geomagnetic field-line resonances and Schumann resonances.

Phylogeography of Lionfishes (Pterois) Indicate Taxonomic Over Splitting and Hybrid Origin of the Invasive Pterois volitans.

The lionfish is an iconic marine fish, and recently renowned for a disastrous introduction into the West Atlantic. Genetic surveys of the putative invaders (Pterois volitans and Pterois miles) in their natural Indo-Pacific range can illuminate both topics. Previous research indicated that P. volitans and P. miles are sister species that hybridize in the invasive range, but hybridization in the native range is unknown. Here, we apply mtDNA COI and 2 nuclear introns (S7 RP1 and Gpd2) from 229 lionfish including the 2 invaders and 2 closely-related taxa (44 P. miles, 91 P. volitans, 31 Pterois lunulata, and 63 Pterois russelii) from 10 locations in their native ranges. Genetic data are supplemented with key morphological characters: dorsal, anal, and pectoral fin ray counts. We observed 2 lineages (d = 4.07%, 0.89%, and 2.75% at COI, S7 RP1, and Gpd2, respectively) among the 4 putative species: an Indian Ocean lineage represented by P. miles, and a Pacific Ocean lineage represented by P. lunulata and P. russelii. All specimens of the invasive P. volitans appear to be hybrids between the Indian Ocean P. miles and a Pacific lineage encompassing P. lunulata/russelii, a conclusion supported by both genetics and morphology. The divergences between Indian and Pacific forms are within the range of species-level partitions in fishes, and we recommend retention of the names P. miles and P. russelii for Indian and Pacific forms. The hybrid origin of the Atlantic invasion invokes the possibility of heterosis as a contributing factor to invasion success.

The quick and ultrasensitive determination of K in NaI using inductively coupled plasma mass spectrometry

A highly sensitive, novel and quick assay method utilizing inductively coupled plasma mass spectrometry was developed for the determination of K in NaI powders and NaI(Tl) scintillator crystals for use in ultralow background applications. The determination of K (viz.40K), as well as Th and U and their daughters, is important in ultralow background detector materials to ensure incorporation of materials of sufficiently high radiopurity. Through the use of improved instrumentation, cool plasma operating conditions, and meticulously clean sample preparations, detection limits of 11 fg natKg−1 (or 341 pBq 40Kkg−1) was attained for K in pure water. Detection limits in the sample matrix (i.e., NaI) were 0.529ng natKg NaI−1 (or 16.4 μBq 40Kkg NaI−1). A number of different precursor NaI powder samples and NaI(Tl) scintillator crystals were assayed for their K content. Determinations ranged from 0.757 to 31.4ng natKg NaI−1. This method allows for the screening of materials to unprecedented levels in a fraction of the time compared to gamma ray counting techniques, providing a useful method for a more effective screening tool of K in ultralow background detector materials.

A New Species of Freshwater Eel-tailed Catfish of the Genus Tandanus (Teleostei: Plotosidae) from Coastal Rivers of Mid-northern New South Wales, Australia

Tandanus bellingerensis, new species, is described based on specimens from four river drainages (Bellinger, Macleay, Hastings, and Manning rivers) of the mid-northern coast of New South Wales, Australia. Previously, three species were recognized in the genus Tandanus: T. tropicanus of the wet tropics region of northeast Queensland, T. tandanus of the Murray-Darling drainage and coastal streams of central-southern Queensland and New South Wales, and T. bostocki of southwestern Western Australia. The new species is distinguished from all congeners by a combination of the following morphologic characters: a high count of rays in the continuous caudodorsal and anal fins (range 153–169, mode 159), a high count of gill rakers on the first arch (range 35–39, mode 36), and strongly recurved posterior serrae of the pectoral-fin spine. Additionally, results from previously conducted genetic studies corroborate morphologic and taxonomic distinctness of the new species.

A new species of the blind and miniature genusMicromyzonFriel and Lundberg, 1996 (Silurifomes: Aspredinidae) from the Orinoco River: describing catfish diversity using high-resolution computed tomography

A new species of the aspredinid catfish tribe Hoplomyzontini Micromyzon is described from two specimens collected with trawl nets in two localities, at 10 and 18 m depth, in the main channel of the lower Orinoco River in Venezuela almost 40 years ago. The new species is distinguished from its only congener, Micromyzon akamai, by the: straight anterior margin of the mesethmoid; open posterior cranial fontanel; ossified first pectoral-fin radial; single tubular infraorbital bone; infraorbital sensory canal entering neurocranium via the frontal; enclosed foramen for the abductor superficialis muscle in the coracoid; higher vertebral count (33 vs. 28–32); higher anal-fin ray count (10 or 11 vs. 7–9); and some morphometric features. The holotype of the new species was scanned using High-Resolution X-ray Computed Tomography to illustrate, describe, and compare its bony skeleton to other hoplomyzontins.

A genetically distinct hybrid zone occurs for two globally invasive mosquito fish species with striking phenotypic resemblance

Hybrid zones allow for the investigation of incipient speciation and related evolutionary processes of selection, gene flow, and migration. Interspecific dynamics, like competition, can impact the size, shape, and directional movement of species in hybrid zones. Hybrid zones contribute to a paradox for the biological species concept because interbreeding between species occurs while parental forms remain distinct. A long‐standing zone of intergradation or introgression exists for eastern and western mosquito fish (Gambusia holbrooki and G. affinis) around Mobile Bay, AL. The region has been studied episodically, over decades, making it perfect for addressing temporal dynamics and for providing a deeper understanding of the genetics of these periodically reclassified fishes (as species or subspecies). We used six microsatellite markers to assess the current population structure and gene flow patterns across 19 populations of mosquito fish and then compared our results with historical data. Genetic evidence demonstrates that the current hybrid zone is located in a similar geographic region as the historical one, even after three decades. Hybrid fish, however, demonstrate relatively low heterozygosity and are genetically distinct from western and eastern mosquito fish populations. Fin ray counts, sometimes used to distinguish the two species from one another, demonstrate more eastern (G. holbrooki) phenotype fish within the molecular genetic hybrid zone today. Mosquito fish are globally invasive, often found on the leading edge of flooded waters that they colonize, so the impact of hurricanes in the wake of climate change was also evaluated. An increase in the frequency and intensity of hurricanes in the hybrid region has occurred, and this point warrants further attention since hurricanes are known to move these aggressive, invasive species into novel territory. This work contributes to our classical understanding of hybrid zone temporal dynamics, refines our understanding of mosquito fish genetics in their native range, evaluates important genotype–phenotype relationships, and identifies a potential new impact of climate change.

Associated particle neutron elemental imaging in vivo: A feasibility study.

The purpose of this study is to develop a Monte Carlo simulation model for in vivo associated particle neutron elemental imaging (APNEI) and to study the feasibility of using APNEI to determine the iron distribution in a human liver with the defined model. The model presented in this study was defined in mcnp by the basic geometry of the human body, the use of D + D source neutrons, iron as the element of interest, an iron-containing voxel in the liver as the target region, and 2 large germanium detectors anterior and posterior to the trunk of the body. The f8 pulse height tally was employed in mcnp to determine the signal acquired from iron inelastic scatter gamma rays at various iron concentrations in the target liver voxel. Correspondingly, the f4 average flux tally in mcnp was modified by a dose function such that the equivalent dose to the whole liver and the effective dose to the whole body could be estimated and used as the basis for a limiting number of neutron histories which could feasibly allow for the collection of a sufficient volume of data to construct a 2D image of iron distribution in the liver voxel. Assuming an allowable equivalent dose to the liver of 5 mSv, 143 inelastic scatter iron gamma ray counts (at ∼847 keV) would ideally be registered at the germanium detectors for a 1 cm3 cube-shaped liver voxel with an iron concentration of 1000 ppm. According to the simulation model, an image of iron distribution in the liver can be constructed with a 1 cm resolution at the level of 1000 ppm iron. Collecting such an image would yield an estimated whole body dose of 0.82 mSv. The mathematical introduction of image uncertainty resulting from source spot diameter and detector timing resolution more closely approximates the result of real world application. APNEI of certain elements in vivo appears feasible given several timing, sensitivity, and resolution caveats. However, further study is required to determine what the detection limit of iron would be and what image resolution would be in an experimental setup as the present model contains idealized assumptions which overestimate the signal attributable to iron inelastic scatter gamma rays.

A New Species of the Bay Goby Genus Eucyclogobius, Endemic to Southern California: Evolution, Conservation, and Decline.

A geographically isolated set of southern localities of the formerly monotypic goby genus Eucyclogobius is known to be reciprocally monophyletic and substantially divergent in mitochondrial sequence and nuclear microsatellite-based phylogenies relative to populations to the north along the California coast. To clarify taxonomic and conservation status, we conducted a suite of analyses on a comprehensive set of morphological counts and measures from across the range of Eucyclogobius and describe the southern populations as a new species, the Southern Tidewater Goby, Eucyclogobius kristinae, now separate from the Northern Tidewater Goby Eucyclogobius newberryi (Girard 1856). In addition to molecular distinction, adults of E. kristinae are diagnosed by: 1) loss of the anterior supratemporal lateral-line canals resulting in higher neuromast counts, 2) lower pectoral and branched caudal ray counts, and 3) sets of measurements identified via discriminant analysis. These differences suggest ecological distinction of the two species. Previous studies estimated lineage separation at 2–4 million years ago, and mitochondrial sequence divergence exceeds that of other recognized fish species. Fish from Santa Monica Artesian Springs (Los Angeles County) northward belong to E. newberryi; those from Aliso Creek (Orange County) southward constitute E. kristinae. The lagoonal habitat of Eucyclogobius has been diminished or degraded, leading to special conservation status at state and federal levels beginning in 1980. Habitat of the newly described species has been impacted by a range of anthropogenic activities, including the conversion of closing lagoons to open tidal systems in the name of restoration. In the last 30 years, E. kristinae has only been observed in nine intermittently occupied lagoonal systems in northern San Diego County; it currently persists in only three sites. Thus, the new species is in imminent danger of extinction and will require ongoing active management.

Barreleye Macropinna sp. (Argentiniformes, Opisthoproctidae) from the Miocene of Sakhalin Island, Russia

ABSTRACTThe first fossil spookfish (Argentiniformes: Opisthoproctidae) is described from deposits of the middle-upper Miocene Kurasi Formation of Sakhalin Island, Russia. The fossil is placed in the family Opisthoproctidae because of the posterior position of its dorsal fin, along with a very small mouth and very long pelvic fin. It is referred further to the genus Macropinna, based on the placement of the anterior margin of the anal fin under the posterior part of dorsal fin, and a close correspondence in vertebra and fin ray counts and body proportions with the only living species, Macropinna microstoma Chapman, 1939. The great similarity between fossil and Recent barreleyes suggests that this Miocene form is a representative of the Recent species or a stem member of M. microstoma.Citation for this article: Nazarkin, M. V. 2016. Barreleye Macropinna sp. (Argentiniformes, Opisthoproctidae) from the Miocene of Sakhalin Island, Russia. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1187158.

Heavy metals detection in sediments using PGNAA method

A prompt gamma ray neutron activation analysis detection system was developed to detect the heavy metals in sediments by using an 241Am-Be neutron source and BGO detector. The samples containing cadmium and mercury were used to test the performance of setup. The linear relationship between prompt gamma ray counts and the concentrations was studied. The results showed the counts of the prompt gamma rays from cadmium do not increase linearly with its concentrations, while the prompt gamma ray counts from Hg vary nearly linearly with the concentrations, due to the neutron self-shielding. Then a method was used to correct the effect and the non-linearly response was restored after the correction. And the minimum detectable concentration of Cd and Hg were 52.8 (at 8.484MeV) and 81.6 (at 5.967MeV) ppm, respectively.

A new species of Gobius (Perciformes: Gobiidae) from the Mediterranean Sea and the redescription of Gobius bucchichi.

A new species of the gobiid genus Gobius (Gobiidae, Perciformes), Gobius incognitus sp. nov. is described from the Mediterranean Sea, and its most morphologically similar species Gobius bucchichi is redescribed. The new species is distinguished from its congeners by: scales in lateral series 51-59; predorsal scales 25-35; opercle scaled in adults with 10-16 scales present; pectoral fin with ray count 18-20 and free tips on upper rays well developed and on the first ray longer than two thirds of the entire ray length; pelvic disc complete and with well-developed anterior membrane without lateral lobes; anterior oculoscapular canal with pore α at rear of orbit; oculoscapular row x(1) not extending forwards to pore β; suborbital row d discontinuous with large gap below suborbital rows 3 and 4; eye diameter 1·08-1·32 in snout length; by pigment rows on cheek and pigmentation on pectoral-fin base.

Rediagnosis of <i>Onigocia grandisquama</i> (Actinopterygii: Perciformes: Platycephalidae) and Comparison with Congeners

A platycephalid fish, Onigocia grandisquama ( Regan, 1908 ) is rediagnosed based on 52 specimens, including the holo-type, from the Indo-West Pacific. Geographic variation in the species was recognized in the number of pectoral-fin rays, the first example of such variation in fin ray counts in the Platycephalidae. The species displays wide intraspecific variation in the numbers of lachrymal, preocular, suborbital, and pterotic spines, with values for the first two overlapping with those of the very similar Onigocia spinosa (Temminck and Schlegel, 1843), making it difficult to separate the two. Onigocia grandisquama can be distinguished from O. spinosa, as well as from Onigocia macrocephala (Weber, 1913) and Onigocia macrolepis (Bleeker, 1854), which share with O. grandisquama an ocular flap on the posterior part of the eye, in lacking spines on the inner, middle, and/or outer ridges of the lachrymal. The generally greater number of pterotic spines also helps to separate O. grandisquama from its three congeners.

A lightning‐based search for nearby observationally dim terrestrial gamma ray flashes

AbstractCurrent space‐based observations of terrestrial gamma ray flashes (TGFs) are capable of identifying only TGFs that exceed a lower brightness threshold. Observationally, dim TGFs that fall below this threshold are consequently difficult to find using photon‐only search algorithms. Such TGFs are a potentially important part of the overall global TGF rate, and information on their occurrence rate would give important insight into TGF generation mechanisms. We describe and implement a lightning‐based search for TGFs that uses the location and time of National Lightning Detection Network reported positive polarity, in‐cloud (+IC) discharges of the type known to be directly associated with TGFs. These events identify a 200 μs search window when any associated TGF photons would have been detected. We show that this approach can detect TGFs without requiring a lower threshold on the detected photon brightness of the event, and thus is capable, in principle, of finding a population of weak TGFs. We find that TGFs occur at a rate between 1 in 40 and 1 in 500 of in‐cloud lightning events that meet our study's criteria. The distribution of gamma ray counts in the search windows exhibits a statistically significant lack of nearby dim TGFs below the GBM search threshold. The data favor a brightness distribution in which nearby observationally dim TGFs are rare.

Maximum Likelihood Localization of Radioactive Sources Against a Highly Fluctuating Background

This paper considers the use of maximum likelihood estimation to localize a stationary source from total gamma ray counts, in an open area setting with a highly fluctuating background. As this turns out to be a highly nonconcave maximization, convergence rates of global convergent algorithms, such as simulated annealing, can be very slow and iterative algorithms such an Newton’s method for maximization can be captured by local maxima while fast. Thus, the selection of the initial estimate is critical to how well they perform. This paper proposes a way to generate such an initial estimate using an averaging process that is shown to be asymptotically convergent to the maximum likelihood source estimate. This ensures that with a sufficiently large number of samples, the initial estimate is indeed within of the basin of attraction of such iterative algorithms. Analytical results are supported by numerical simulations based on a measured background data and synthetically injected source data.

Correlation between numerical simulation and limited data experimental technique for estimation of nitrogen flowing in LMMHD loop

Predictions by numerical simulation with estimations by Computerized Tomographic (CT) results for two component two phase flow system are compared. Motivation is to improve/deduce a strategy for a possible correlation between simulation and experimental results by employing appropriate mathematical and physical modeling. Three-dimensional simulation is performed using ANSYS Fluent 14.0®. Flow regimes considered in this work vary from churn-turbulent to bubbly flow. Changes in bubble diameter with pressure are considered. Grid independent adaptively-regularized entropy maximization CT algorithm is employed. It facilitates reconstruction with high grid resolution. A-priori information is used for calibration of this CT algorithm with real life measurements. Beer–Lambert law is used to interpret the measured gamma ray counts instead of preferred conventional method of chord average projection data. Mixture model shows negligible mismatch between two approaches for low (less than 10%) nitrogen holdup and Euler–Euler model beyond this range. Correlation relation is obtained and used for matching profile of 40LPM with real time measurements.