Ray Counts Research Articles

Gamma spectroscopy studies of the underwater hydrothermal vent field of the Methana Peninsula

A preliminary study of natural radioactivity was conducted on the thermal spas in Methana Peninsula. To carry out this research, a collection of 17 water samples were taken from thermal springs around and underwater of the volcanogenic Peninsula at depths ranging 0–5 m. The Methana peninsula belongs to the Hellenic Volcanic Arc and is characterized by hydrothermal vent activity. A NaI(Tl) scintillator (AMESOS) was used to carry out gamma–ray counting of the samples to deduce the activity concentrations of the natural radionuclides of the 238U and 232Th decay series, as well as 40K in spa waters. Results are expected to provide information on the geological setting of the Methana peninsula. The impact of naturally occurring radioisotopes to human health has also been assessed in terms of the radiation dose risk corresponding to the measured activities.

Conodont biostratigraphy and magnetic susceptibility of Upper Devonian Chattanooga Shale, eastern United States: Evidence for episodic deposition and disconformities

Recognition of stratigraphic hiatuses in fine-grained siliciclastic sedimentary rocks can be challenging but is feasible using high-resolution biostratigraphic and chemostratigraphic data within a regional correlation framework. In this case study of the Upper Devonian Chattanooga Shale in the Dupont GHS drillcore from the western margin of the Nashville Dome, the Upper Devonian Chattanooga Shale comprises several depositional units separated by intraformational hiatuses. These features are developed within a 13.3 m interval consisting of 4.2 m of Frasnian strata and 9.1 m of Famennian strata that unconformably overlie the Sellersburg Formation. Three Frasnian, seven Famennian, and one Tournaisian conodont biozones are recognized. The Frasnian-Famennian boundary is on a disconformity. To the northeast in the southern Illinois Basin, the New Albany Shale in the BCC drillcore consists of 35 m of Givetian and Frasnian strata and 30 m of Famennian strata that conformably overlie the Sellersburg Formation. One Givetian, four Frasnian, and three of the four lowest Famennian conodont zones are recognized. The Frasnian-Famennian boundary is conformable and constrained to within a 5 cm interval. Bulk magnetic susceptibility (MS) shows a long-term increase through most of the Frasnian. Shorter-term MS trends were observed in association with depositional pulses linked to global sea-level rises and highstand system tracts, characterized by total organic carbon (TOC) maxima — eight trends were resolved in the DGHS core, and six in the BCC. The high-frequency shifts in δMS likely represent Milankovitch-band sea-level and depositional cycles at a scale that cannot be resolved based on the condensed and irregular nature of the depositional packages. Gamma ray counts in the DGHS peak in association with the eight depositional cycles, with a TOC peak at the base of each cycle.

Galactic Cosmic-Ray Anisotropies: Voyager 1 in the Local Interstellar Medium

Abstract Since crossing the heliopause on 2012 August 25, Voyager 1 observed reductions in galactic cosmic ray count rates caused by a time-varying depletion of particles with pitch angles near 90°, while intensities of particles with other pitch angles remain unchanged. Between late 2012 and mid-2017, three large-scale events occurred, lasting from ∼100 to ∼630 days. Omnidirectional and directional high-energy data from Voyager 1’s Cosmic Ray Subsystem are used to report cosmic ray intensity variations. Omnidirectional (≳20 MeV) proton-dominated measurements show up to a 3.8% intensity reduction. Bidirectional (≳70 MeV) proton-dominated measurements taken from various spacecraft orientations provide insight about the depletion region’s spatial properties. We characterize the anisotropy as a “notch” in an otherwise uniform pitch angle distribution of varying depth and width centered about 90° in pitch angle space. The notch averages 22° wide and 15% deep, signifying a depletion region that is broad and shallow. There are indications that the anisotropy is formed by a combination of magnetic trapping and cooling downstream of solar-induced transient disturbances in a region that is also likely influenced by the highly compressed fields near the heliopause.

Morphological Differences and Trophic Niche Breadth of Sarotherodon galilaeus and Oreochromis niloticus from the Freshwater Lake Geriyo, North-Eastern Nigeria

Abstract The relationship between morphological traits and feeding ecology of the only two tilapiine cichlids (Sarotherodon galilaeus and Oreochromis niloticus) in Lake Geriyo, northeastern Nigeria, was examined. Stomach contents of 504 individuals were examined and analyzed to relate morphological differences of each species to its dietary preferences. Eleven ecological relevant morphological variables, including total length, standard length, head length, body depth, eye diameter, pectoral spine length, pelvic spine length, dorsal fin ray count, dorsal spine count and anal fin ray count, were also measured and subjected to Principal coordinate analysis (PCoA) to relate morphological differences of each species to its dietary preferences. The PCoA (using Euclidean distance) revealed a large morphological distance between species indicating adaptation for different spatial and vertical distributions within the lake. Furthermore, the correlation of these morphological differences with particular diet categories suggests a potential for specialized trophic tendencies, however, the high occurrence of two major food types (macrophytes and plankton) in stomach contents of both species indicate generalist trophic tendencies. While a high trophic overlap index (0.98) was recorded for both species, the trophic niche breadth was higher for S. galilaeus (4.18±0.32), compared to O. niloticus (3.33±0.24). Despite the large morphological differences of both tilapias, the high trophic overlaps indicate limited food options within Lake Geriyo. In addition, the successful coexistence of the tilapias in the face of limited food resources indicates suitable partitioning of food resources in the lake.

Simulation Study on the Feasibility of Current-mode SPECT for B-10 Concentration Estimation in Boron Neutron Capture Therapy

Boron neutron caputure therapy (BNCT) is a promising treatment for invasive tumors. The BNCT utilizes the energy deposition by alpha particle and 7Li created by the neutron capture reaction of 10B. One of the problem of BNCT is the imaging of 10B distribution during the treatment. The gamma rays with the energy of 0.478 MeV emitted by 7Li can be exploited for this purpose. The photon counting of the gamma rays, however, is very difficult due to the high gamma ray background caused by 2.22 MeV gamma rays originated by the neutron reactions with 1H. To overcome this difficulty, the authors propose a method to measure gamma rays as electric current by a “transXend” detector, which had been invented by them for energy-resolved X-ray computed tomography. In this paper, the feasibility study on 10B distribution imaging in a water phantom with a tumor region is shown by simulation studies. For establishing the relationship between electric currents induced in the transXend detector by gamma rays and 10B concentration, the attenuation of gamma rays by the phantom should be taken into account. For this purpose, a neural network was employed. The results showed good agreement with the training data used for the neural network.

Pulsed Transcranial Red/Near-Infrared Light Therapy Using Light-Emitting Diodes Improves Cerebral Blood Flow and Cognitive Function in Veterans with Chronic Traumatic Brain Injury: A Case Series.

Objective: This study explored the outcome of applying red/near-infrared light therapy using light-emitting diodes (LEDs) pulsed with three different frequencies transcranially to treat traumatic brain injury (TBI) in Veterans.Background: Photobiomodulation therapy (PBMT) using LEDs has been shown to have positive effects on TBI in humans and animal models.Materials and methods: Twelve symptomatic military Veterans diagnosed with chronic TBI >18 months post-trauma received pulsed transcranial PBMT (tPBMT) using two neoprene therapy pads containing 220 infrared and 180 red LEDs, generating a power output of 3.3 W and an average power density of 6.4 mW/cm2 for 20 min, thrice per week over 6 weeks. Outcome measures included standardized neuropsychological test scores and qualitative and quantitative single photon emission computed tomography (SPECT) measures of regional cerebral blood flow (rCBF).Results: Pulsed tPBMT significantly improved neuropsychological scores in 6 of 15 subscales (40.0%; p < 0.05; two tailed). SPECT analysis showed increase in rCBF in 8 of 12 (66.7%) study participants. Quantitative SPECT analysis revealed a significant increase in rCBF in this subgroup of study participants and a significant difference between pre-treatment and post-treatment gamma ray counts per cubic centimeter [t = 3.77, df = 7, p = 0.007, 95% confidence interval (95,543.21–21,931.82)]. This is the first study to report quantitative SPECT analysis of rCBF in regions of interest following pulsed tPBMT with LEDs in TBI.Conclusions: Pulsed tPBMT using LEDs shows promise in improving cognitive function and rCBF several years after TBI. Larger, controlled studies are indicated.

Trait variation in extreme thermal environments under constant and fluctuating temperatures.

Climate change is increasingly exposing populations to rare and novel environmental conditions. Theory suggests that extreme conditions will expose cryptic phenotypes, with a concomitant increase in trait variation. Although some empirical support for this exists, it is also well established that physiological mechanisms (e.g. heat shock protein expression) change when organisms are exposed to constant versus fluctuating temperatures. To determine the effect of common, rare and novel temperatures on the release of hidden variation, we exposed fathead minnows, Pimephales promelas, to five fluctuating and four constant temperature regimes (constant treatments: 23.5, 25, 28.5 and 31°C; all fluctuating treatments shared a minimum temperature of 22°C at 00.00 and a maximum of 25, 28, 31, 34 or 37°C at 12.00). We measured each individual's length weekly over 60 days, critical thermal maximum (CTmax), five morphometric traits (eye anterior-posterior distance, pelvic fin length, pectoral fin length, pelvic fin ray count and pectoral fin ray count) and fluctuating asymmetry (FA, absolute difference between left and right morphometric measurements; FA is typically associated with stress). Length-at-age in both constant and fluctuating conditions decreased with temperature, and this trait's variance decreased with temperature under fluctuating conditions but increased and then decreased in constant temperatures. CTmax in both treatments increased with increasing water temperature, while its variance decreased in warmer waters. No consistent pattern in mean or variance was found across morphometric traits or FA. Our results suggest that, for fathead minnows, variance can decrease in important traits (e.g. length-at-age and CTmax) as the environment becomes more stressful, so it may be difficult to establish comprehensive rules for the effects of rarer or stressful environments on trait variation. This article is part of the theme issue 'The role of plasticity in phenotypic adaptation to rapid environmental change'.

First Record of Longspine Grouper, Epinephelus longispinis (Kner, 1864) from Gujarat, North-West Coast of India

A single specimen of longspine grouper was collected at a depth of 30–40 m by a single day trawler from the waters of Gujarat. The species is considered as ‘least concern’ by IUCN. The fish was examined for key morphometric and meristic characters such as body length and depth, head length, fin lengths, spine and rays counts, lateral line scale count, gill rakers count, shape and distribution pattern of spots on the body. The present study reports the first record of the species from north-west coast of India describing its extension of geographical distribution and addition of one more species to the biodiversity of Gujarat.

A spectrometer with baseline correction and fast pulse pile-up rejection for prompt gamma neutron activation analysis technology.

The prompt gamma neutron activation analysis (PGNAA) technology is an online nondestructive material analysis technology widely used in industries. In order to achieve real-time measurements, the gamma ray count rate should reach 400 kcps. Due to the limitation of the detector's decay time, the signal output from the detector is heavily piled up. Meanwhile, the industrial site has a temperature fluctuation of 0-50 °C, causing the peak drift in the energy spectrum. This paper presents a readout electronic system specified for PGNAA and proposes series of algorithms that are dedicated for the gamma-ray spectrometric system. The system can achieve a count rate of 400 kcps, and it overcomes poor resolution, spectral distortion, and peak position shift, which are caused by pulse pileups and temperature fluctuations.

Pulsed Transcranial Red/Near-Infrared Light Therapy Using Light-Emitting Diodes Improves Cerebral Blood Flow and Cognitive Function in Veterans with Chronic Traumatic Brain Injury: A Case Series.

This study explored the outcome of applying red/near-infrared light therapy using light-emitting diodes (LEDs) pulsed with three different frequencies transcranially to treat traumatic brain injury (TBI) in Veterans. Photobiomodulation therapy (PBMT) using LEDs has been shown to have positive effects on TBI in humans and animal models. Twelve symptomatic military Veterans diagnosed with chronic TBI >18 months post-trauma received pulsed transcranial PBMT (tPBMT) using two neoprene therapy pads containing 220 infrared and 180 red LEDs, generating a power output of 3.3 W and an average power density of 6.4 mW/cm2 for 20 min, thrice per week over 6 weeks. Outcome measures included standardized neuropsychological test scores and qualitative and quantitative single photon emission computed tomography (SPECT) measures of regional cerebral blood flow (rCBF). Pulsed tPBMT significantly improved neuropsychological scores in 6 of 15 subscales (40.0%; p < 0.05; two tailed). SPECT analysis showed increase in rCBF in 8 of 12 (66.7%) study participants. Quantitative SPECT analysis revealed a significant increase in rCBF in this subgroup of study participants and a significant difference between pre-treatment and post-treatment gamma ray counts per cubic centimeter [t = 3.77, df = 7, p = 0.007, 95% confidence interval (95,543.21-21,931.82)]. This is the first study to report quantitative SPECT analysis of rCBF in regions of interest following pulsed tPBMT with LEDs in TBI. Pulsed tPBMT using LEDs shows promise in improving cognitive function and rCBF several years after TBI. Larger, controlled studies are indicated.

A new tapertail species (family Radiicephalidae; Lampridiformes) from Taiwan, the first confirmed western Pacific Ocean record of the family

Radiicephalus kessinger sp. nov. (Lampridiformes: Radiicephalidae), described from a single specimen collected off southwestern Taiwan, represents a formerly monotypic and rarely collected family, known almost entirely from the eastern Atlantic Ocean, although some unsupported larval records exist from the north and eastern Pacific oceans. Radiicephalus kessinger can be distinguished from the only other congener R. elongatus Osorio 1917 on the basis of fin ray and vertebral counts, fin ray positions and lengths, lateral line position, jaw shape, dorsal body outline and teeth patterns. The specimen represents the first record of the family in the western Pacific Ocean, there being no reliable records or voucher specimens of the family from the Indo-West Pacific region. New information is given on scales and coloration of R. elongatus, based on examination of the neotype and additional specimens.

Diagnostics of Gymnocanthus pistilliger (Pallas, 1814) and G. galeatus Bean, 1881 (Scorpaeniformes: Cottidae) in their Cohabitation Areas

Sex-independent characters for identification of Gymnocanthus pistilliger and G. galeatus in their cohabitation areas were revealed: the presence, position, and arrangement of rough bony plates on the interorbital space, as well as the total spine and ray count for all fins (dorsals and anal; doubled number of rays in pectoral). The interorbital space of G. galeatus is completely covered by bony plates; the spine and ray count for all fins is 82−89. In G. pistilliger, the interorbital space is naked (26%) or has only a few bony plates that never extend onto the rim of the orbit; the spine and ray count for all fins is 74−81. In the eastern part of the Sea of Okhotsk, G. galeatus is not common and perhaps might be found here only occasionally.

The evolution of underwater flight: The redistribution of pectoral fin rays, in manta rays and their relatives (Myliobatidae)

Batoids are a diverse clade of flat cartilaginous fishes that occur primarily in benthic marine habitats. The skates and rays typically use their flexible pectoral fins for feeding and propulsion via undulatory swimming. However, two groups of rays have adopted a pelagic or bentho-pelagic lifestyle and utilize oscillatory swimming-the Myliobatidae and Gymnuridae. The myliobatids have evolved cephalic lobes, anteriorly extended appendages that are optimized for feeding, while their pectoral fins exhibit several modifications that likely arose in association with functional optimization of pelagic cruising via oscillatory flight. Here, we examine variation in fin ray distribution and ontogenetic timing of fin ray development in batoid pectoral fins in an evolutionary context using the following methods: radiography, computed tomography, dissections, and cleared and stained specimens. We propose an index for characterizing variation in the distribution of pectoral fin rays. While undulatory swimmers exhibit symmetry or slight anterior bias, we found a posterior shift in the distribution of fin rays that arose in two distinct lineages in association with oscillatory swimming. Undulatory and oscillatory swimmers occupy nonoverlapping morphospace with respect to fin ray distribution illustrating significant remodeling of pectoral fins in oscillatory swimmers. Further, we describe a derived skeletal feature in anterior pectoral fins of the Myliobatidae that is likely associated with optimization of oscillatory swimming. By examining the distribution of fin rays with clearly defined articulation points, we were able to infer evolutionary trends and body plan remodeling associated with invasion of the pelagic environment. Finally, we found that the number and distribution of fin rays is set early in development in the little skate, round stingray, and cownose ray, suggesting that fin ray counts from specimens after birth or hatching are representative of adults and therefore comparable among species.

Two new deep-water species of the genus Thorogobius (Teleostei: Gobiidae) from the upper continental slope of the Eastern Central Atlantic.

Two new gobiid species, Thorogobius alvheimi sp. nov. and Thorogobius laureatus sp. nov. (Teleostei: Gobiiformes: Gobiidae), are described from the outer continental shelf and upper slope of the Eastern Central Atlantic off Angola, Ghana and São Tomé and Príncipe. The specimens were trawled from depths between 57 and 208m. The new species are most similar to Thorogobius angolensis. Thorogobius alvheimi sp. nov. is distinguished from its congeners in the combination of following characters. Fins: first dorsal fin with the second and third spines distinctly elongated; pectoral fin ray count 20-21; pelvic disc complete and short with well-developed anterior membrane (frenum) and pointed lateral lobes. Scales: nape and predorsal area naked; no scales on opercle; scales in longitudinal series 27-31. Pattern of free neuromasts: supratemporal rows tr and trp developed, extending transversally between pores H and K; longitudinal row g short, not passing row m posteriorly and distinctly distant from row h; infraorbital row 6 long, ventrally extending to lower margin of preopercle, its ventral section 6i originating anterior to its dorsal section 6s; posterior lateral row h reaching anteriorly above posterior third of opercle. Coloration: body uniformly pale fawn and brown; margin of scale pockets dark brown pigmented, yielding a reticulated pattern; pale spots on nape and predorsal area; caudal fin uniformly dusky greyish. Thorogobius laureatus sp. nov. is distinguished from its congeners in the combination of following characters. Fins: first dorsal fin the second and third spines distinctly elongated; pectoral fin ray count 19-22; pelvic disc complete, short, with well-developed anterior membrane (frenum) with pointed lateral lobes. Scales: scales on sides of predorsal area and midline mostly naked; no scales on opercle; scales in longitudinal series 24-27. Pattern of free neuromasts (sensory papillae): supratemporal rows tr and trp developed, extending transversally between pores H and K; longitudinal row g long, passing row m posteriorly and relatively close to row h; infraorbital row 6 long, ventrally extending to lower margin of preopercle, its ventral (6i) and dorsal (6s) originating opposite to each other; posterior lateral rows: row h long, reaching anteriorly above middle of opercle. Coloration: body pale fawn and brownish; margin of scale pockets dark brown pigmented, yielding a reticulated pattern; five brown blotches on flanks in lateral midline from below first dorsal fin to caudal peduncle; caudal fin with six or seven distinct dark vertical bands.

The identity of Aplocheilus andamanicus (Köhler, 1906) (Teleostei: Cyprinodontiformes), an endemic Killifish from the Andaman Islands, with notes on Odontopsis armata van Hasselt.

In his work on the fishes of the Andaman Islands, Francis Day (1870) collected large-sized specimens of Aplocheilus from the south Andamans. Despite differences in the size and dorsal-fin ray counts, Day refrained from recognising the Andaman Aplocheilus as a distinct species and considered it as Aplocheilus panchax, a species distributed in the Ganges delta and across the eastern coast of mainland India. However, Day mentioned the differences in fin-ray counts between these two populations. Subsequently Köhler (1906) described the Andaman population as Haplochilus andamanicus (now in Aplocheilus), referring to the diagnostic characters initially discovered by Day. This species failed to receive recognition from taxonomists, because of the uncertainty regarding the validity of the species and its questionable synonymy with A. panchax. In this study, based on morphological and molecular evidence, we demonstrate that A. andamanicus is indeed a distinct and valid species, which can easily be diagnosed from the widespread A. panchax. While resolving the identity of A. andamanicus, we also demonstrate that the congeners from southeast Asia form a genetically distinct group for which the name Odontopsis armata is available.

A reverse ray-tracing method for modelling the net radiative flux in leaf-resolving plant canopy simulations

Radiation is a direct or indirect driver of essentially all biophysical processes in plant systems, and is commonly described through the use of models because of its complex distributions in time and space. Detailed radiation transfer models that represent plant-scale heterogeneity have high computational resource requirements, thus severely limiting the size of problems that can be feasibly considered, while simplified models that can represent entire canopies usually neglect heterogeneity across a wide range of scales. This work develops new methods for computing radiation absorption, transmission, scattering, and emission using ray-tracing approaches that can explicitly represent scales ranging from leaves to canopies. This work focuses on developing a new “reverse” ray-tracing method for describing radiation emission and scattering that ensures all geometric elements (e.g., leaves, branches) are adequately sampled, which guarantees that modelled radiative fluxes are bounded within a reasonable range of values regardless of the number of rays used. This is a critical property when complex model geometries are used, which can be subject to severe sampling errors even when very large ray counts are used. The presented model uses graphics processing units (GPUs) along with highly optimized software to efficiently perform ray-object intersection tests in parallel. This allowed for the simulation of >500 fully resolved trees on a desktop computer in under five minutes.

English

Studies have been done on the variability of cosmic rays flux during solar quiet days at mid and high latitudes. By using the 5 quietest days for each month, the monthly mean diurnal variation of cosmic ray anisotropy have been derived for the period 1981 to 2007, which covers part of cycles 21, 22 and 23. These quiet days are days during which the sun is relatively magnetically quiet, leading to less anisotropic behaviour in the diurnal flux of cosmic rays measured on the earth surface. Four stations (Rome, Oulu, Inuvik and Thule) were used in this study to understand the important features of the high latitude and mid-latitude diurnal wave, and how solar and geomagnetic activity may be influencing the wave characteristics. Cosmic ray wave characteristics were obtained by discrete Fourier transform (DFT). The mean, diurnal amplitude, phase and dispersion for each month's diurnal wave were calculated and profiled. There was clear indication that the terrestrial effect on the variability of the monthly mean of Cosmic ray count rates was more associated with geomagnetic activity rather than rigidity of the cosmic rays. Correlation of the time series of these wave characteristics (that is, amplitude and phase) with solar and geomagnetic activity index showed better association with solar activity. Key words: Cosmic rays, Fourier Transformation, solar quiet day, geomagnetic activity solar activity.

Monte Carlo simulation of Cu, Ni and Fe grade determination in borehole by PGNAA technique

A prompt gamma neutron activation analysis borehole logging method for copper, nickel and iron grade estimation is proposed. The performance of the method was simulated by MCNP5 code. Based on the theory of neutron–gamma distribution on the borehole condition, the BGO scintillator and 3He neutron tube are adopted to record gamma ray spectrum and thermal neutron simultaneously, and least square method is used for the characteristic gamma ray counts calculation in the high energy range. The results of detection limit of metal grade in borehole condition indicate that the effectiveness of this logging method.

Investigation of large α production in reactions involving weakly bound Li7

The origin of the large $\ensuremath{\alpha}$-particle production cross sections in systems involving weakly bound $^{7}\mathrm{Li}$ projectiles has been investigated by measuring the cross sections of all possible fragment-capture as well as complete fusion using the particle-$\ensuremath{\gamma}$ coincidence, in-beam, and off-beam $\ensuremath{\gamma}$-ray counting techniques for the $^{7}\mathrm{Li}+^{93}\mathrm{Nb}$ system at near Coulomb barrier energies. Almost all of the inclusive $\ensuremath{\alpha}$-particle yield has been accounted for. While the $t$-capture mechanism is found to be dominant ($\ensuremath{\sim}70%$), compound nuclear evaporation and breakup processes contribute $\ensuremath{\sim}15%$ each to the inclusive $\ensuremath{\alpha}$-particle production in the measured energy range. Systematic behavior of the $t$ capture and inclusive $\ensuremath{\alpha}$ cross sections for reactions involving $^{7}\mathrm{Li}$ over a wide mass range is also reported.

Evaluation of absolute measurement using a 4π plastic scintillator for the 4πβ−γ coincidence counting method

Absolute measurement by the 4πβ-γ coincidence counting method was conducted by two photomultipliers facing across a plastic scintillator to be focused on β ray counting efficiency. The detector was held with a through-hole-type NaI(Tl) detector. The results include absolutely determined activity and its uncertainty especially about extrapolation. A comparison between the obtained and known activities showed agreement within their uncertainties.