Experimental development of a gated UV-induced spectroscopic lidar for the daytime study of plant ecology and photosynthesis: multi-modal measurement of fluorescence of trees growing in a field and Mie-Raman-fluorescence of the surrounding atmosphere.

A gated UV-induced spectroscopic lidar operational during daylight was developed to better understand the plant growth status in real time and the influence from the surrounding atmosphere chemical environment. Initial indoor experiments and short-range (100 m) field measurements were very positive. The lidar worked as a vegetation fluorescence lidar, as well as an atmospheric Mie-Raman-fluorescence lidar. A UV (355 nm) laser was effective to induce fluorescence and Raman scattering, and a synchronous detection technique made it possible to detect weak signals, even in daytime. Tree spectra containing chlorophyll fluorescence of tree leaves offered information about the growth status of trees. Atmospheric spectra containing aerosol Mie scattering, N 2, O 2, H 2 O Raman scattering, and pollutant fluorescence helped us to learn about atmospheric circumstances surrounding trees. The multi-modal information is useful for comprehensive understanding of plant ecology.

Initial experimental multi-wavelength EEM (Excitation Emission Matrix) fluorescence lidar detection and classification of atmospheric pollen with potential applications toward real-time bioaerosols monitoring.

Fluorescence has the potential to identify the types of substances associated with aerosols. To demonstrate its usefulness in environmental studies, we investigated the use of Excitation-Emission-Matrix (EEM) fluorescence in lidar bioaerosol monitoring. First, the EEM fluorescence of cedar, ragweed, and apple pollens as typical bioaerosols found around our surroundings were measured using a commercial fluorescence spectrometer. We found that the patterns of fluorescence changed depending on the pollen type and excitation wavelength and it meant that studying these EEM fluorescence patterns was a good parameter for identifying pollen types. Then, we setup a simple EEM fluorescence lidar to confirm the usefulness in lidar bioaerosol monitoring. The lidar consisted of three laser diodes and one light emitting diode with output at 520 nm, 445 nm, 405 nm and 325 nm, respectively, an ultra violet camera lens as a receiver, and a fluorescence spectrum detection unit. Comparing the lidar simulation results with the EEM fluorescence dataset supported the possibility of performing bioaerosol monitoring using the EEM fluorescence lidar. Based on the results and the current technology, a feasible design of a bioaerosol detection EEM fluorescence lidar is proposed for future rel-time remote sensing and mapping of atmospheric bioaerosols.

Collection of excitation-emission-matrix fluorescence of aerosol-candidate-substances and its application to fluorescence lidar monitoring.

Fluorescence lidars have the potential to identify aerosols, but it seems that the basic data of the fluorescence spectrum of various aerosols appear to be inadequate for practical use in application of fluorescence lidar monitoring. We collected the fluorescence spectrum data of 61 powders with different substances as pseudo-aerosols and organized them as EEM (Excitation-Emission-Matrix) fluorescence data. Our interest was also in the artificial substances that are discarded around our surroundings and become aerosols. Four applications of the EEM fluorescence to fluorescence lidars were discussed; designing fluorescence lidars, reconstructing aerosol fluorescence spectrums measured by fluorescence lidar, searching for new substances for fluorescence lidar measurement, and developing a database of EEM fluorescence for identifying aerosol types measured by fluorescence lidar. All EEM fluorescence data and application software were stored in one USB memory and run in the BIOS (Basic Input/Output System) independent of a computer OS (Operating System) for ease of use. Aerosol identification software worked well in general, but we have also talked a bit about improvements.

Post-Embryonic Development and Genital-Complex Formation in Three Species of Polyclad Flatworms.

Without the establishment of effective culturing systems, little can be known about the late developmental stages of polyclad flatworms. Here, we report a laboratory culturing system for three polyclad species: Comoplana pusilla, Notocomplana koreana, and Pseudostylochus obscurus, and we describe changes in their morphology from hatching to reproductive maturity. These species hatch out as lobe-less larvae with four eyespots, but the number of eyespots increases in later development. Cross-like and triangularly shaped larvae are observed in N. koreana and P. obscurus, respectively. After settlement, a pale area appears on the body of juveniles and then develops into the copulatory complexes. All three species could be successfully reared on brine shrimp, but only C. pusilla and N. koreana achieved reproductive maturation in such a culturing system. In P. obscurus, switching the food to the gastropod Monodonta labio induced sexual maturation.

Design and daytime performance of laser-induced fluorescence spectrum lidar for simultaneous detection of multiple components, dissolved organic matter, phycocyanin, and chlorophyll in river water.

In this work, we developed mobile laser-induced fluorescence spectrum (LIFS) lidar based on preliminary experiments on the excitation emission matrix of a water sample and a method for reducing solar background light using the synchronous detection technique. The combination of a UV short-pulse laser (355 nm, 6 ns) for fluorescence excitation with a 10-100 ns short-time synchronous detection using a gated image-intensified multi-channel CCD of the fluorescence made the LIFS lidar operation possible even in daytime. The LIFS lidar with this construction demonstrated the potential of natural river/lake water quality monitoring at the Tenryu River/Lake Suwa. Three main components in the fluorescence data of the water, dissolved organic matter, phycocyanin, and chlorophyll, were extracted by spectral analysis using the standard spectral functions of these components. Their concentrations were estimated by adapting experimentally calibrated data. Results of long-term field observations using our LIFS lidar from 2010 to 2012 show the necessity of simultaneous multi-component detection to understand the natural water environment.

Development of a UV laser-induced fluorescence lidar for monitoring blue-green algae in Lake Suwa.

We developed a UV (355 nm) laser-induced fluorescence (LIF) lidar for monitoring the real-time status of blue-green algae. Since the fluorescence spectrum of blue-green algae excited by 355 nm showed the specific fluorescence at 650 nm, the lidar was designed to be able to detect the 650 nm fluorescence as a surveillance method for the algae. The usefulness was confirmed by observation at Lake Suwa over four years (2005-2008). The detection limit of the LIF lidar was 16.65 mg/L for the blue-green algae, which is the range of concentrations in the safe level set by the World Health Organization.

Estimating organ dose with optimized peak dose index in cone-beam CT scans.

PURPOSE: Organ dose evaluation is important for optimizing cone beam computed tomography (CBCT) scan protocols. However, an evaluation method for various CBCT scanners is yet to be established. In this study, we developed scanner-independent conversion coefficients to estimate organ doses using appropriate peak dose (f(0)) indices. METHODS: This study included various scanners (angiography scanners and linear accelerators) and protocols for the head and body (thorax, abdomen, and pelvis) scan regions. f(0) was measured at five conventional positions (center position (f(0)c) and four peripheral positions (f(0)p) at 90° intervals) in the CT dose index (CTDI) phantom. To identify appropriate measurement positions for organ dose estimation, various f(0) indices were considered. Organ doses were measured by using optically stimulated luminescence dosimeters positioned in an anthropomorphic phantom. Thereafter, the conversion coefficients were calculated from each obtained f(0) value and organ or tissue dose using a linear fit for all scanners, and the coefficient of variation (CV) of the conversion coefficients was calculated for each organ or tissue. The f(0) index with the minimum CV value was proposed as the appropriate index. RESULTS: The appropriate f(0) index was determined as f(0)c for the body region and a maximum of four f(0)p values for the head region. Using the proposed conversion coefficients based on the appropriate f(0) index, the organ/tissue doses were well estimated with a mean error of 14.2% across all scanners and scan regions. CONCLUSIONS: The proposed scanner-independent coefficients are useful for organ dose evaluation using CBCT scanners.

ON and OFF channels in human retinal ganglion cells.

The ON and OFF channels are basic functional elements in parallel processing in the visual system in vertebrates including primates. We analysed the responses of the optic tract fibre activity in response to switching a flashlight on or off in 25 awake patients with Parkinson's disease who underwent stereotactic surgery targeting the internal globus pallidus. The responses were evoked in a darkened room by a light with a luminance of approximately 4 × 10(4) cd m(-2) at the eye and a wide-spectrum wavelength. Most of the responses at the light on event were excitatory (38 out of 41 sites, 93%). Thirty-five sites with increase in activity at the light on event showed reciprocal responses or no responses to light off, and these sites were classified as containing ON fibres. In single-fibre analysis, all of 14 ON fibres were recorded at the sites of multi-fibre excitatory responses. Six sites showed multi-fibre excitatory responses at the light off event; three sites showed sustained reduction in activity at the light on event, and these three sites were classified as containing OFF fibres. In single-fibre analysis, two OFF fibres were recorded at the sites of multi-fibre suppressive responses at the light on event, and the other two OFF fibres were recorded at the sites of multi-fibre excitatory responses at the light on event. We found that all excitatory responses to light on were transient, while all but one excitatory responses to light off were sustained. Reduction in activity tended to be smaller than increase in activity at the light on event. These results demonstrate that the ON and OFF channels, and their transient and sustained features function in visual processing in humans.

Self and nonself recognition in a marine sponge, Halichondria japonica (Demospongiae).

The function of allogeneic recognition in a marine sponge, Halichondria japonica, was examined by use of cut pieces contact assay. Individuals of this species were able to distinguish an allogeneic individual from an autogeneic one, and showed rejection reactions against allogeneic individuals. There were two types of allogeneic rejection reaction: barrier formation at the contact area to separate from allogeneic individuals and necrosis with cytotoxic reactions at the contact area. In both types of rejection reactions, mesohyl cells accumulate at the contact area at the early stages of the rejection reaction. Fusion between two pieces of allogeneic individuals was very rare, and in most of combinations of allogeneic individuals rejection reactions appeared at the contact area. Xenogeneic rejections were also observed. Halichondria japonica showed rejection reaction against individuals of Halichondria okadai, but the intensity of rejection was less than that of allogeneic rejection.

Impact of Dose Perturbations Around Brachytherapy Seeds in External-Beam Radiotherapy Planning: A Fundamental and Clinical Validation Using Treatment Planning System-Based Monte Carlo Simulations.

Background This study evaluates dose perturbations caused by nonradioactive seeds in clinical cases by employing treatment planning system-based Monte Carlo (TPS-MC) simulation. Methodology We investigated dose perturbation using a water-equivalent phantom and 20 clinical cases of prostate cancer (10 cases with seeds and 10 cases without seeds) treated at Fujita Health University Hospital, Japan. First, dose calculations for a simple geometry were performed using the RayStation MC algorithm for a water-equivalent phantom with and without a seed. TPS-independent Monte Carlo (full-MC) simulations and film measurements were conducted to verify the accuracy of TPS-MC simulation. Subsequently, dose calculations using TPS-MC were performed on CT images of clinical cases of prostate cancer with and without seeds, and the dose distributions were compared. Results In clinical cases, dose calculations using MC simulations revealed hotspots around the seeds. However, the size of the hotspot was not correlated with the number of seeds. The maximum difference in dose perturbation between TPS-MC simulations and film measurements was 3.9%, whereas that between TPS-MC simulations and full-MC simulations was 3.7%. The dose error of TPS-MC was negligible for multiple beams or rotational irradiation. Conclusions Hotspots were observed in dose calculations using TPS-MC performed on CT images of clinical cases with seeds. The dose calculation accuracy around the seeds using TPS-MC simulations was comparable to that of film measurements and full-MC simulations, with differences within 3.9%. Although the clinical impact of hotspots occurring around the seeds is minimal, utilizing MC simulations on TPSs can be beneficial to verify their presence.

Validation of deep learning-based CT image reconstruction for treatment planning.

Deep learning-based CT image reconstruction (DLR) is a state-of-the-art method for obtaining CT images. This study aimed to evaluate the usefulness of DLR in radiotherapy. Data were acquired using a large-bore CT system and an electron density phantom for radiotherapy. We compared the CT values, image noise, and CT value-to-electron density conversion table of DLR and hybrid iterative reconstruction (H-IR) for various doses. Further, we evaluated three DLR reconstruction strength patterns (Mild, Standard, and Strong). The variations of CT values of DLR and H-IR were large at low doses, and the difference in average CT values was insignificant with less than 10 HU at doses of 100 mAs and above. DLR showed less change in CT values and smaller image noise relative to H-IR. The noise-reduction effect was particularly large in the low-dose region. The difference in image noise between DLR Mild and Standard/Strong was large, suggesting the usefulness of reconstruction intensities higher than Mild. DLR showed stable CT values and low image noise for various materials, even at low doses; particularly for Standard or Strong, the reduction in image noise was significant. These findings indicate the usefulness of DLR in treatment planning using large-bore CT systems.

Dosimetric and radiobiological analyses of a de-escalation strategy for elective nodal regions in human papillomavirus-associated oropharyngeal cancer.

Introduction: In this simulation study, we examined the effects of a de-escalation strategy with a reduced dose to subclinical nodal regions in patients with human papillomavirus (HPV)-associated oropharyngeal carcinoma (OPC). Methods: We created two patterns of intensity-modulated radiotherapy for 16 patients with HPV-associated OPC. In the standard and de-escalation plans, the initial field including elective nodal regions received 46 and 30 Gy, followed by 20 and 36 Gy to the cutdown field, respectively. Comparison metrics were set for each organ at risk (OAR). We compared these metric values and the probability of adverse effects based on the normal tissue complication probability (NTCP) model between the two plans. Results: Both plans generally met the dose constraints for the targets and all OAR. Among the comparison metrics, the mean doses to the brain, pharyngeal constrictor muscle, thyroid, and skin and the dose to a 1 % volume of the skin were higher in the standard plan than in the de-escalation plan (P = 0.031, 0.007, < 0.001, < 0.001, and 0.006, respectively). NTCP analyses revealed that the probability of adverse effects in the ipsilateral parotid gland and thyroid was higher in the standard plan than in the de-escalation plan (standard vs. de-escalation plans: ipsilateral parotid gland, 6.4 % vs. 5.0 %, P = 0.016; thyroid, 3.3 % vs. 0.5 %, P < 0.001). Conclusions: A de-escalation strategy with elective nodal regions is a promising treatment to prevent a decline in the quality of life in patients with HPV-associated OPC, particularly xerostomia, dysphagia, and hypothyroidism.

Simple quality assurance based on filtered back projection for geometrical/irradiation accuracy in single-isocenter multiple-target stereotactic radiotherapy.

In single-isocenter multiple-target stereotactic radiotherapy (SIMT-SRT), it is difficult to evaluate both the geometrical accuracy and absorbed dose measurement when irradiating off-isocenter targets. This study aimed to develop a simple quality assurance (QA) method to evaluate off-isocenter irradiation position accuracy in SIMT-SRT and compare its feasibility with that of a commercial device. First, we created two types of inserts and metallic balls with a diameter of 5 mm to be inserted into a commercially available phantom (SIMT phantom). Second, we developed a dedicated analysis software using Python for the Winston-Lutz test (WLT). Third, an image processing software, including the filtered back-projection algorithm, was developed to analyze the images obtained using an electronic portal imaging device (EPID). Fourth, the feasibility of our method was evaluated by comparing it with the results of WLT using two commercially available phantoms: WL-QA and MultiMet-WL cubes. Notably, 92% of the results in one-dimensional deviations were within 0.26 mm (EPID pixel width). The correlation coefficients were 0.52, 0.92, and 0.96 in the left-right, superior-inferior, and anterior-posterior directions, respectively. In the WLT, a maximum two-dimensional deviation of 0.70 mm was detected in our method, while the deviation in the other method was within 0.5 mm. The advantage of our method is that it can evaluate the geometrical accuracy at any gantry angle during dynamic rotation irradiation using a filtered back-projection algorithm, even if the target is located off the isocenter. Our method can perform WLT at arbitrary positions and is suitable for the QA of dynamic rotation irradiation using an EPID.

Sodium temperature lidar based on injection seeded Nd:YAG pulse lasers using a sum-frequency generation technique.

We report on a sodium (Na) temperature lidar based on two injection seeded Nd:YAG pulse lasers using single-pass sum-frequency generation. The laser power at 589 nm is 400 mW (40 mJ per pulse at a repetition rate of 10 Hz) and the pulse width is 22 nsec FWHM. The narrowband laser tuned to the Doppler broadened Na D2 spectrum enables us to measure the temperature of the mesopause region (80-115 km). This solid-state transportable system demonstrated high performance and capability at Syowa Station in Antarctica for 3 years and at Uji in Japan for an additional year without any major operational troubles.

Studies on Japanese botryllid ascidians. V. A new species of the genus Botrylloides very similar to Botrylloides simodensis in morphology.

Botrylloides simodensis, belonging to the family Botryllidae, is a common species on the rocky shore around Shimoda. Since this species was first reported in 1981, it has been noticed that some B. simodensis colonies have distinctly different ground colors and color patterns from colonies including type specimens (holotype and all of paratypes) of B. simodensis. However, as there is no remarkable difference among them in morphology other than the colonial colors and color patterns, they have been considered to belong to the same species. In the present work, colonies of B. simodensis sensu lato were divided into three groups, two major and one minor, based on their color-morphs and periods of sexual reproduction. In one of the major groups, B. simodensis sensu strict, the period of sexual reproduction was limited from July to September, as shown in the original description. The other major group engaged in sexual reproduction for much longer than the former group, and they frequently made clusters of vascular vessels and underwent vascular budding. Therefore, the group with the long period of sexual reproduction was described as a new species of the genus Botrylloides here. In addition, phylogenetic analysis based on mtDNA sequences of these groups indicated that each group had a peculiar sequence, and that they were genetically separated.

A new cone-beam computed tomography dosimetry method providing optimal measurement positions: A Monte Carlo study.

PURPOSE: The conventional weighted computed tomography dose index (CTDIw) may not be suitable for cone-beam computed tomography (CBCT) dosimetry because a cross-sectional dose distribution is angularly inhomogeneous owing to partial angle irradiations. This study was conducted to develop a new dose metric (f(0)CBw) for CBCT dosimetry to determine a more accurate average dose in the central cross-sectional plane of a cylindrical phantom using Monte Carlo simulations. METHODS: First, cross-sectional dose distributions of cylindrical polymethyl methacrylate phantoms over a wide range of phantom diameters (8-40 cm) were calculated for various CBCT scan protocols. Then, by obtaining linear least-squares fits of the full datasets of the cross-sectional dose distributions, the optimal radial positions, which represented measurement positions for the average phantom dose, were determined. Finally, the f(0)CBw method was developed by averaging point doses at the optimal radial positions of the phantoms. To demonstrate its validity, the relative differences between the average doses and each dose index value were estimated for the devised f(0)CBw, conventional CTDIw, and Haba's CTDIw methods, respectively. RESULTS: The relative differences between the average doses and each dose index value were within 4.1%, 16.7%, and 11.9% for the devised, conventional CTDIw, and Haba's CTDIw methods, respectively. CONCLUSIONS: The devised f(0)CBw value was calculated by averaging four "point doses" at 90° intervals and the optimal radial positions of the cylindrical phantom. The devised method can estimate the average dose more accurately than the previously developed CTDIw methods for CBCT dosimetry.

Development of the nervous system in the acorn worm Balanoglossus simodensis: insights into nervous system evolution.

To examine the evolutionary origin of the chordate nervous system, an outgroup comparison with hemichordates is needed. When the nervous systems of chordates and hemichordates are compared, two possibilities have been proposed, one of which is that the chordate nervous system has evolved from the nervous system of hemichordate-like larva and the other that it is comparable to the adult nervous system of hemichordates. To address this issue, we investigated the entire developmental process of the nervous system in the acorn worm Balanoglossus simodensis. In tornaria larvae, the nervous system developed along the longitudinal ciliary band and the telotroch, but no neurons were observed in the ventral band or the perianal ciliary ring throughout the developmental stages. The adult nervous system began to develop at the dorsal midline at the Krohn stage, considerably earlier than metamorphosis. During metamorphosis, the larval nervous system was not incorporated into the adult nervous system. These observations strongly suggest that the hemichordate larval nervous system contributes little to the newly formed adult nervous system.

Morphological characterization of the asexual reproduction in the acorn worm Balanoglossus simodensis.

The acorn worm Balanoglossus simodensis reproduces asexually by fragmentation and subsequent regeneration from the body fragments. We examined the morphogenesis of its asexual reproduction. At first, we collected asexually reproducing specimens and observed their morphogenesis. Then, we succeeded in inducing the asexual reproduction artificially by cutting the worm at the end of the genital region. The process of morphogenesis is completely the same between naturally collected and artificially induced specimens. The stages during morphogenesis were established on the basis of the external features of the asexually reproducing fragments. The internal features of the fragments were also examined at each stage. In a separate phase of the study, the capacity for regeneration of some body parts was also examined by dividing intact worms into about 10 fragments. Although the capacity for regeneration varied among the different body parts, some fragments regenerated into complete individuals in 1 month. The process of regeneration was the same as that in the asexually produced fragments.

Evaluation of differences and dosimetric influences of beam models using golden and multi-institutional measured beam datasets in radiation treatment planning systems.

PURPOSE: The beam model in radiation treatment planning systems (RTPSs) plays a crucial role in determining the accuracy of calculated dose distributions. The purpose of this study was to ascertain differences in beam models and their dosimetric influences when a golden beam dataset (GBD) and multi-institution measured beam datasets (MBDs) are used for beam modeling in RTPSs. METHODS: The MBDs collected from 15 institutions, and the MBDs' beam models, were compared with a GBD, and the GBD's beam model, for Varian TrueBeam linear accelerator. The calculated dose distributions of the MBDs' beam models were compared with those of the GBD's beam model for simple geometries in a water phantom. Calculated dose distributions were similarly evaluated in volumetric modulated arc therapy (VMAT) plans for TG-119 C-shape and TG-244 head and neck, at several dose constraints of the planning target volumes (PTVs), and organs at risk. RESULTS: The agreements of the MBDs with the GBD were almost all within ±1%. The calculated dose distributions for simple geometries in a water phantom also closely corresponded between the beam models of GBD and MBDs. Nevertheless, there were considerable differences between the beam models. The maximum differences between the mean energy of the energy spectra of GBD and MBDs were -0.12 MeV (-10.5%) in AcurosXB (AXB, Eclipse) and 0.11 MeV (7.7%) in collapsed cone convolution (CCC, RayStation). The differences in the VMAT calculated dose distributions varied for each dose region, plan, X-ray energy, and dose calculation algorithm. The ranges of the differences in the dose constraints were -5.6% to 3.0% for AXB and -24.1% to 2.8% for CCC. In several VMAT plans, the calculated dose distributions of GBD's beam model tended to be lower in high-dose regions and higher in low-dose regions than those of the MBDs' beam models. CONCLUSIONS: We found that small differences in beam data have large impacts on the beam models, and on calculated dose distributions in clinical VMAT plan, even if beam data correspond within ±1%. GBD's beam model was not a representative beam model. The beam models of GBD and MBDs and their calculated dose distributions under clinical conditions were significantly different. These differences are most likely due to the extensive variation in the beam models, reflecting the characteristics of beam data. The energy spectrum and radial energy in the beam model varied in a wide range, even if the differences in the beam data were <±1%. To minimize the uncertainty of the calculated dose distributions in clinical plans, it was best to use the institutional MBD for beam modeling, or the beam model that ensures the accuracy of calculated dose distributions.

Ambulacrarian prototypical Hox and ParaHox gene complements of the indirect-developing hemichordate Balanoglossus simodensis.

The Hox genes and its evolutionary sister, the ParaHox genes, are widely distributed among animals. Although it has been expected that hemichordates and echinoderms have a single set of Hox genes and most likely a single set of ParaHox genes, it is not known whether the ortholog of Hox8 is absent in hemichordates, and in turn, consensus view about Hox/ParaHox gene complements in hemichordates has not been established. In this study, we isolated either complete or nearly complete coding sequences of 12 Hox genes, including the ortholog of the Hox8 that has not been reported in the previous studies, and three ParaHox genes from the recently discovered indirect-developing acorn worm, Balanoglossus simodensis. Our data suggest that the ancestral hemichordate had intact complements of ambulacrarian prototypical Hox and ParaHox genes, consisting of 12 and three members, respectively.